Host Response PDF

So we talked about what is gingivitis, which is an inflammatory disease can have different acute and chronic inflammatory response associated with a dental biofilm. As we said, we have those three histopathological stages by Paige and Schroeder as we described. And we're having pretty much inflammat...

So we talked about what is gingivitis, which is an inflammatory disease can have different acute and chronic inflammatory response associated with a dental biofilm. As we said, we have those three histopathological stages by Paige and Schroeder as we described. And we're having pretty much inflammation of the gingival epithelium and connective tissue. On the other hand, potentially it's like getting infectious inflammatory disease, a combination of that. It's considered pretty much a chronic disease only because of how it happens. That's why. Remember we said with the classification the eliminated the aggressive form because as a pathogenesis it's pretty much the same mechanism. It just happens faster with more destruction etcetera. We call it a complex multifactorial disease. We're going to talk about that in our next presentation too. But it's kind of diseases that a lot of factors may play a role over that genetics may play a role in that. That's why we call it like this. We consider that it's initiated primarily by bacteria, especially the gram negative anaerobic bacteria. And we have a cascade of host immune response mechanisms that are being activated, which lead eventually to the destruction of the supporting tissues of the teeth. So these are all the theories that we already talked about in previous lectures as well. And as you see in the 1800s, they're the golden age of microbiology. We had the microscopes, we could see the bacteria. And that's how this different hypothesis started from the nonspecific and eventually to the keystone plaque hypothesis that we described last time as well. So let's see how all this thing works. Last time I had a slide which I didn't like too much, but I just put it there for your reference. But this is what I need you to remember. This is the essence of barrier disease. If you have printed out the classification, you may print that as well and see that it's colorful. So it all starts like the bacterial challenge. Everything that happens with the host immune inflammatory response, everything that plays a role with the LPs, the virulence factors as we said, and how the antibodies and the neutrophils and everything exists as cytokines. We're going to see all of those how we're going to have progressing to the connective tissue and bone metabolism, the different factors genetic, environmental. We're going to talk about those next time and eventually leading to the clinical signs of the disease. So we talked about the bacteria everything that we know about the bacterial challenge. So today we're going to work with those two purple blue whatever you see them columns in the middle. So and as we said for disease to occur the bacteria must be virulent. That's why we have those virulence factors. The LPs as we said, they have to exceed a quantitative critical threshold. We described and talked about that the presence just of the species per se does not necessarily mean disease. It has to have a clinical threshold for disease to be cured. It has to conquer the antagonistic microorganisms. As we see, we know how biofilm works with all these commensal bacteria and then eventually overcome host response and create these inflammatory response. And what we're going to be seeing today is pretty much the underlying mechanisms from going to a healthy state to a diseased state. Okay, we're going to see what's happening underneath. So we talked about the balance before. And that's everything that's happening in our body. We as we said we all have a normal flora, not only in the oral cavity and other mucous membranes in our body. And we just need to have this in a state of balance, equilibrium with our host. So the host is effective against whatever bacteria is being found there. We have good bacterial challenge in the conductive environment. And that's how everything works for the for the human, for the patient. Now, if we start having this equilibrium like imbalance between those two, either because we have a reduced or defective like host defense against specific bacterial challenge, or if we have increased bacterial challenge that overwhelms the host defense. That's when we start having this state of disease. So that's everything. What happens in our treatment so far aim to. Challenge more the bacterial intake because we know what we can do. We just need to remove it, give our chemotherapeutic whatever we decide and try to bring back to the things, to the to in a balanced situation. There have been some efforts in addressing the host as well. With host modulation. We're going to learn about that in next semester. Yep. I'm going to give some hints today, but there have been some efforts with that. Obviously you can not only target that, you may find some good outcomes, but it's as we said previously, host response is a complex mechanism that happens, and we need to be careful how we address each aspect of that. So what I need you to see here is like you see how the bacteria start becoming more pathogenic, a lot of them becoming a little bit more mobile. And you will see the more pathogenic they become, the more mobile they start becoming in this situation. And eventually, as you see with the clinical picture, when you start having plaque accumulation, you see approximately there are some plaque accumulation and eventually what you will be seeing of what's happening there. So clinically, clinically you will start seeing the redness, the edema, erythema, swelling, etcetera. So we remember those phases and we talked about that. What we see clinically today, we're going to see what we will be seeing sub clinically pretty much we talked about that last time as well with those pristine gingiva which is very rare to see that. But even in this situation you may still see some spores like neutrophils or interleukin eight like a cytokine. There being this is the balance that we want to have. So the fact that you have those inflammatory let's say cells and inflammatory mediator doesn't mean that you have disease. So that's what I need you to understand. So when we go to the initial lesion which again you can't see much clinically it appears healthy. But clinically we have obviously the neutrophils the artesian molecules as we see here in some lymphocytes and macrophages in the area I get in a balance between these bacterial challenge that starts to gather on that marginal gingiva progressing to the early lesion we're seeing clinically. You see marginal erythema some swelling some delayed or not bleeding on probing etcetera. Obviously you will have more lymphocytes and neutrophils, some plasma cells showing up. We start having cell damage with the fibroblasts and loss of the gingival collagen, and eventually going to the established lesion where you have in those established gingival inflammation with more severe signs with severe bleeding, more swelling edema. You're having increased gingival cervical fluid flow, mainly more plasma cells collagen and fibroblasts. Fibroblast damage increased leukocytes in the connective tissue. So you see how everything connects gathers over there to start fighting the the bacterial the microbial challenge that happens over there and eventually in the burden tide is where you're having the advanced lesions. You're mainly having plasma cells, obviously extensive damage to the collagen fibers, loss of connective tissue attachment, deeper pocket. And you see how the lesion migrates more quickly towards the PDL, the bone et-cetera. So whatever we saw that happens clinically and we diagnose that that's what's happening sub clinically. And that's why we see those clinical signs clear okay. So and remember those five signs of inflammation that we talked in our few lectures ago. And what happens like in period in the periodontitis in terms of heat and redness. Obviously we can't measure the heat unless we put a micro thermometer over there. But obviously we have increased heat and redness because we have invasive dilation and increased blood flow in the area. We're having swelling because we're having increased vascular permeability with leakage of plasma proteins and accumulation of inflammatory cells. And we're having pain, although in period diseases we don't have excruciating pain like an indoor issue or something or a fracture caries. But again, people may be sensitive in the gingiva. And in more severe cases they may describe and they may report pain where you're having stimulation of different like nerves with chemical mediators of inflammation that's happening in the area. So the main characteristics of the immune system that we need to keep in mind is the specificity diversity memory and self tolerance. So these things help the immune system to work in whatever challenge it may. Have to encounter. So for example with specificity they can recognize specific cell surface antigens. With diversity you can have we will see we have those B and T cells and the lymphocytes that are triggered with an immune reaction. And they can recognize any different shape pattern that you may find on the bacteria memory. Obviously you can have memory in the immune system. That's why we do also the vaccines when we go over, you know, a flu or something. We develop this memory. So next time we're getting challenged with that, the body remembers okay. We seen that before. We know we don't like it. We can target it right away. So it's more faster reaction to whatever is happening. And obviously self tolerance when the system recognizes and differentiates between foreign invaders and self components and obviously issues in those areas, that's when you're having those own autoimmune diseases where the body doesn't recognize what's the body's own cell and target those cells. So and that's what happens here when we're having breakdown of self tolerance. We're having those autoimmune diseases. And when we're having defects in the immune system for whatever various reasons that's where we're having immunodeficiency like because of medications systemic disorders or anything that may happen. And regarding immunity, there are two types that you need to remember the innate and the adaptive. So I have those characteristics here that a bullet so that you can remember them. So they need immunity is nonspecific and which is what we call the first line of defense okay. We usually don't get any memory with that. And we have circulating molecules that complement and a bunch of cells as you see over here, the neutrophils the natural killer cells etcetera that play a role. And this initiates pretty much the inflammatory response. On the other hand the adaptive immunity it's more specific. We're having the memory we're having specialized immune response. We're having antibodies and cytokines that circulate in the body. It recognizes specific features. We're having mainly the T cells and B cells. We're going to talk about all those things and those these can further more be divided to the cellular immunity with which is T cell mediated and the humoral immunity which is B cell mediated. And that's what we call the immunological response. And I just have it here with those categories of the immunity, what's happening with the innate and the adaptive. So you see that with the adaptive immunity you have more diversity and memory compared to the innate one. And you're having the B cells and T cells for the adaptive antibody cytokines. While in the innate you're having the neutrophils monocytes and the complement that plays a role. So different types of that. And if I can have a scheme on those things that's how pretty much how they made and the adaptive immunity works. So obviously there can be an overlap. It's not like distinct properties. And depending on how things work there's both immunity start to overlap. But just realizing which cells play a role and why over there. And what I have on this one is exactly how with the bacterial plug, we have both those responses. The mediators may lead to the communication between the innate and the adaptive one. We said about the adaptive with a T cells and B cells, that humoral and cell mediated response, while we're having the more inflammatory response in the in this innate immunity with all the cells that play a role. So that's pretty much the schematic diagram of what's happening there. And I do have another slide here to regarding the humoral and the cell mediated one, so that you see which cells play a role. That's part of the adaptive immunity. Remember we can have this T cells T cell mediated and B cell mediated one. So with the humoral one that's when you start having the B cells playing a role. Production of antibodies. While with the T cells the T cells play a role. And specific types of them target the cells and the bacteria that need to be targeted to bring back to balance and homeostasis. Questions in that. Nope. And again, as always, I have it as a table here for your reference. What's happening between the humoral and the cell mediated ones? Which cells play a role? You need to know the differences where the B cells are, where the T cells are, and and the B cells we have the antibodies B antibody. Maybe you can remember it like that T cells. You have this cell to cell contact. And how we have the primary defense against specific pathogens intracellular versus extracellular pathogens depending on the immunity. So that's the basic information that you need to understand in order to understand how the immunity works in burial. And let's find the key components of the host defense in those periodontal diseases. And you do see here we have in the inflammatory response epithelium saliva humoral and cell mediated response and the several mediators. So we're going to go step by step over here. And I know there's a bunch of information again for your reference. What needs to be kept in mind is that a rapid response of the tissues. You're having several functions like to kill the bacteria, protect the host of the bacterial invasion. It's usually it's relatively nonspecific. The gingival cervical fluid plays a significant role, especially as a result of the acute inflammation. And remember we have increased of the flow of the volume. A lot of studies that tried to investigate subclinical parameters in high risk patients, they do measure the gingival fluid, so they measure the volume. They measure the mediators that you can find in there. What you see. You can have a lot of mediators in that. So depending on what you find you can understand the pathogenesis a question. Nope. Okay. You can understand the pathogenicity of what's happening in that specific slide. And eventually you're having neutrophils that are part of the first line of defense. And macrophages. We're going to talk about those cells in a little bit which play a significant function. As we said macrophages is a key cell to the inflammation. Regarding the epithelium that's obviously a physical barrier to plaque microorganisms. We're having the epithelial cells. Remember the corona versus non corona epithelium. Remember that those areas that have chronic epithelium have more resistance. For example the cold space. Remember what the call space is the area between the contact area between teeth the tissues non colonized epithelium. So the approximately patients may not do a good job may not floss or may not remove bacteria. Ilium is less resistance or in presence of pathogenic bacteria. Inflammation can start easier. So does make sense how things connect over there. And obviously it's part of the inflammatory response. We have specific cells in the junctional epithelium and that really cytokines and expression of like peptides as we see over here. And part of the immune response were the Langerhans cells. We talked about those in the anatomy lecture that play a role in the whole inflammatory the immune response in the gingival epithelium. Regarding saliva, we need to keep in mind that those effects are mainly the antimicrobial effects are mainly super gingival. It doesn't have direct effects of gingival. And obviously if you're having a patient that has your system because of any medical condition of any treatment, let's say radiation of specific medication, these predisposes the patient to development of supra gingival plaque. And eventually, you know, sub gingival plaque as well. But the presence of that, since we don't have the good work of the saliva and the effects of that we can have, patient is more prone to caries, gingivitis. ET cetera. And again, I'm just oh yeah it's here. So the antimicrobial features I just included these for your reference and I'm not going to just read it out. But what I need you to keep in mind is that a lot of studies evaluating, again, subclinical parameters, they take saliva samples of the patients and they analyze them. But what you need to keep in mind in those studies is that they just gather what's happening supra gingival. And they may not be so accurate. They may just pull data of whatever is happening in the oral cavity. Obviously, it has a significant effect. It has a lot of factors and proteins and cytokines that help. But again, understanding where the effect is on regarding the humoral immune response. This is what we said. We have the antibody production. So we're having the epithelial Langerhans cells that are recognizing the antigenic bacteria. They present it to the circulating lymphocytes. Then they recognize the specific antigen. And then they go through a specific sequence of clonal expansion in order to produce the antibodies. So the B the B cells B the lymphocytes differentiate into plasma cells that secrete the antibody against the antigen under the control of T helper cells, and they try to have the antibody production in order to protect the host of the challenge, especially the IgG and IGA, and eventually those. Antibodies may be produced systemically or locally, depending on the challenge, the bacterial challenge that you have. And this is also something that again, and I'm bringing it back because a lot of studies have been made for those of clinical parameters. When measuring inflammation, it's important to differentiate what's happened systemically versus locally. And there are things that systemically they may affect any local, you know, areas that you may initiate inflammation. The same thing was brought up way more significantly after with Covid, to be honest, where they started to study inflammation and develop this hyper inflammatory response activation may have. And if a patient is susceptible to anything that includes inflammation with Covid with the disease may. Uh, have more pronounced like, let's say, clinical features or long term side effects from, let's say, patients, the apparently say patients with asthma or etc. with Alzheimer's, with other inflammatory diseases. There's even been studies with Covid and period, because of this systemic inflammatory response that was more exaggerated and exacerbated with Covid. So all those things play a role, and it's important to understand the difference between those. So as a scheme here, as an illustration of what happens with the humoral immune response to the antigens, we see that we're having the plaque over here that goes through the junctional epithelium. The first barrier over there, you're having the Langerhans cells which recognize the plaque. They take the antigens and they present it to the macrophages. They leave the gingiva through the lymphatic system. They go to the lymph nodes. They become to stimulate and produce specific immune response. And eventually going. And this is all for the humoral immune response. So we're having specific antibodies for those very little bacteria produced by those plasma cells. Remember the four pages of the four stages of Page and Schroeder. The last column with the advanced lesion. What was the main cells that you would find their plasma cells okay. Now it makes sense why we have those over here. And then those antibodies are being carried out to be brought again out to the cellular area in order to target the bacteria and create that response to that. So that's the circle. Clear. Okay, so let's go with a similar thing. What happens with the cell mediated response. So in this response we mainly have the T helper lymphocytes that produce cytokines assist the differentiation of B cells into plasma cells and activate neutrophils and macrophages. So in gingivitis we mainly have the T helper one cells. While in parentheses we have the T helper two cells that shift into B cells over here. And the same thing that I had before the first three numbers which I have it. Oh, let me see. One. There you are. The first three numbers over here is exactly the same in terms of presence of plaque, Langerhans cells, recognition and antigen presenting cells. So this is exactly the same thing. We're going to go back to this illustration over here. So the difference now is that you're having the T cells and the specific they proliferate into the lymph nodes and enter the bloodstream. And those specific lymphocytes they go back production of cytokines. They start the cell mediated immune response and start to target the area. So everything happens together right. It's not like a separate thing. That's why you see it's the whole at the same time you can have your antibodies and you're going to have the T cells that play a role on that side. And finally finishing with the mediators that play a role there. So what are mediators? They are like soluble like chemical messengers that can regulate and provide a link between the inflammatory response, the immune response and the tissue damage. You will be hearing about cytokines and mediators all the time wherever you're reading about perio and especially inflammatory diseases. So we're having those pro-inflammatory cytokines as you see here, examples of interleukin one six, tumor necrosis factor alpha, etcetera that play a role in the inflammation. You can have the prostaglandins. Usually we write them as PGE. So especially the PGE two as we see over here responsible for bone resorption neutrophil chemotaxis and vascular permeability matrix metallo proteases the MMP as you see them being written so they are pro-inflammatory and have an impact on the connective tissue degradation. And other like proteases and protease inhibitors. So all those things, they're all being found there. And depending on the severity of the inflammation, you will find specific numbers of those mediators being more elevated versus in health. You will find absence of specific proinflammatory molecules that play a role over there. So everything that we said so far, we talked about the bacteria. This is what we've been talking about. The antibodies, the antigens, the neutrophils and how the first host immune inflammatory response starts to work in periodontal diseases. Regarding cytokines, what I need you to remember, because I have a slide afterwards, which is like a case, like it's like a map with all the cytokines. I need you to remember which ones are the most like the frequently seen pro-inflammatory, which you can see in studies that lead to tissue destruction, especially interleukin one six TNF alpha, interferon. That's what I IFN stands for. And which ones are promoting the healing, which are the anti-inflammatory like the interleukin ten four and TGF beta. So you will see that a lot of studies that target the host response to shift from the inflammatory feeling like inflammation to back to healthy state. They try to promote and regulate more of those cytokines so that we have more healing processes. Because what you also need to keep in mind, we have and we need the immune response for wound healing as well. Right? It's not always bad. We like it because otherwise whenever we had an injury we would not be able to survive. So having said that, we need the parts of the immune response that plays a role with a healing and the wound healing. But there's a fine line here. So fine like this point over here that if you overcome and you go to the other side, then you're leading to the tissue destruction. And obviously why this is being initiated. As we will learn, there's a lot of factors in that. So as we said about cytokines or signaling molecules, they mediate and regulate the immunity inflammation. And they are secreted by specific cells in the immune system. And there's a whole network of that as you see over here. What's happening. The computer doesn't want you to see the network because it's scary. Yes. Of course. So, yeah, I don't want you to remember all this by heart, but that's what's happening. You will see that a lot of specific interleukins like interleukin one, which is one of the most well studied, you know, pro-inflammatory cytokines, comes up again and again in every of those connections. So you see how this is starting with the macrophages with the first line, then how other cells are being secreted when those are being released, and how the release of those triggers other cells to be secreted. It's like a whole network in that. So this network, as we say, can like those cytokines can be grouped loosely in those six families the interleukins, the cytotoxic the colony stimulating factors, interferons, IFN as we said, growth factors and chemokines. So very loosely differentiation in those and the action of cytokines. The action of cytokines can have an effect on other cytokines depending on which category they belong to. So it can cause like different effects to the target cell. It could be the it could elicit the response from other targets. It could be synergistic. So you need to have a couple of cytokines or more to work together or antagonistic. So the one cytokine blocks the other. So depending on what you're looking for you can see the different interactions over there. Clear. Okay? No. What? Sorry. What? It's a lot. That's what you said, I know. Did they say that? It's not a lot in the beginning. I said it's super dense, I was honest. Okay, I'm trying to. I know it looks chaotic, but I have. I have something at the end that may or may help you. We'll see. So I'm sorry. What? No, it's not a quiz. So regarding prostaglandins, as we said, we you see them being written as PGE. So these are products of the Cox pathway. Okay. Let's talk a little bit about that. So as you see over here, when you're having the. Production of the arachidonic acid, you have those three pathways. And we're going to aim over here. So you're having the Cox or Cox pathway. That's how people are saying that an X logs pathway. And that's where the prostaglandins are being created. So these are part of the of the inflammation. And they lead eventually to the plasma membrane degradation the destruction. And they're responsible for the prolonged phase of vascular permeability. So what you need to keep in mind here because obviously they can stimulate bone resorption and and the leukotrienes. So you see the light as we see over here. They can they can chemo tract. They can be as chemo attractants for neutrophils. Cetera. So what is important over here. And a lot of studies especially I mentioned that name. Dr. Van Dike was doing a lot of studies with resolving and resolution of inflammation. They try to block these pathway. And you see here those red ones, this is part of the whatever we're going to learn about host modulation. So they're trying to block this pathway especially the ones with the prostaglandins. Because what happens over here with like things that are natural inhibitors of inflammation. You want to block those in order to have more production of those. So that's how the whole concept starts over there. What I need you to remember from that is from this very complicated mechanism where the prostaglandins are coming from, which pathway where the leukotrienes and the light boxes are coming from the log pathway. And that's where exactly a lot of medications you see here, aspirin and NSAIDs are blocking, especially even when you're having any response, inflammatory response that can lead to pain inflammation. That's where they block over there okay. Don't get lost with those. But just remember those two things where prostaglandins and leukotrienes are coming from. Okay. So the maps, the matrix metropolitan ACS. So these are a group of enzymes that are responsible for the degradation of extracellular matrix. We can see increased expression of those in pathological conditions. And a lot of studies are starting the MMP eight which is considered an indicator again indicator for disease severity. So obviously when you're taking a sample and you're seeing increased numbers of MMP, you're assuming there's a lot of inflammation happening there. And then you are associated with your clinical findings where you're seeing destruction and everything. So you're saying obviously we're having disease on that side. Clear with those. Okay, let's go to the cells. We don't have enough yet, right? Yeah I know. So what we need to keep in mind, we have a bunch of cells that play a role in the immune system. We talked briefly about the B cells and the T cells and all those things. But everything, all the cells that are coming from the blood stem cell, like as you see here from red blood cells and white blood cells, play a significant role in the inflammation. So where are those? Everything is in the blood as we see. We see the erythrocytes, the red blood cells that play a role, the thrombosis and platelets that initiate the clotting cascade. I have a slide for that as well, in case you had any doubt. The white blood cells, which are an integral component of the immune response, and we're going to go cell by cell over there. And obviously the plasma that that's the fluid portion of the blood that has a lot of antibodies. The complement as you see here, the CRP proteins, fibrinogen, etcetera. So everything all these things play a role in the inflammation. They're all in the blood and the different cells over there. And let's go step by step regarding the platelets. They play the part in the initial hemostasis as a platelet plug. They extrude like growth factors which are which are associated and involved with wound healing. And what do we have in the growth factors we're having like cytokines, as we said, that are proteins that are stored in the platelet and help with a homeostasis on that side and the aggregate to the connective tissue and getting activated in order to create the clot and start to close the wound. Whatever is happening on that side in the same factor, because we talked about the growth factors and everything that's happening there. The platelet rich plasma is a source of the growth factors that support the bone and soft tissue healing. So the blood clot initiates the soft tissue healing. And then it starts having like the healing process with the natural clot and the PRP clot and all of these things and reaches like the PRP and reaches the natural clot for a more healing process. And why is it important? Because you see how many growth factors you can have over there inside. And a lot of newer materials they are including like growth factors, especially when doing surgeries for dental surgeries. A lot of doctors now are using the PRP. When you're taking blood from your patient, you're differentiating the plasma and everything. You're taking the PRP, using it as a membrane for the wound healing and trying to enhance your regenerative outcome, the wound healing outcome when treating periodontal defects. Yes. Your purpose is pure. I'm sorry. I didn't. Hear you. Do you practice injections in yoga, too? Okay. To the gums. To the gingiva. Yes. Me personally, I've used a couple of times. I don't do it regularly, depending on the practice that you have. Obviously, for you to use the PRP. You need to be certified to be able to draw blood. Otherwise you need to have a phlebotomist there to do this for you. There practices that may have in their courses that can give it to you if you're interested. But the PRP as a concept, what I need you to understand is like it's so it's seen that it's so useful with a wound healing and the clotting that they use it in many areas in medicine, like even ophthalmology, andrology, whatever you may think of specific surgeries, like even major surgeries, they use that because they want to take advantage of all those growth factors that we have over there, enhancing the wound healing and a lot of dental like periodontal materials are growth factors. But materials, those I use them like regularly. They come in vials that you mix them with your bone grafting, whatever you will using. And those factors initiate and promote. Apart from the wound healing, also the bone formation that you want in specific regenerative procedures. Either it's bone grafting on an identity less areas around teeth depending on what you do. Okay. Any other question? No. So I mentioned about the CRP the C reactive protein. I have two things over here. We're going to talk about that later on as well. So it's going to be connected together. So the protein is a member of the class of the acute phase that plays a role in the inflammation. It's thought to assist the complement I have a slide about the complement as well and plays a role to the humoral response to the disease. Again, a lot of studies that investigate inflammatory diseases, they evaluate the protein in their levels because they can associate their levels with the clinical findings that they have. So on a similar note, let's go to those white blood cells and I need you to those five ones. Just remember the key bullets that I have on the slides in questions may come for those cells. So keeping those in mind. So the eosinophil we call it like this. Because when you stain them with eosin they stain pink. So like reddish they play a major role in the host response in specific even parasitic invasions. And the granules can include a bunch of like enzymes and proteins, as you see over here. On the other hand, the basophils, as you see over here, they stain blue. So like more basic the environment, when you stain it over here, it's the least abundant leukocyte. And the granules can contain like histamine heparin things like that. Regarding the lymphocytes we already talked about those. And now we're just going to break it down a little bit regarding the B cells and the T cells and the NK the natural killer cells as we said over here. So these are the ones that are being differentiated into plasma cells to produce the antibodies. And the T cells differentiate in different T cell types that have a specific role in the cell mediated immunity. And as we see over here, the T cells differentiate to T helper cells natural killer cells, the cytotoxic cells and the memory cells and the B cells. Depending on how you they are being activated, they're producing the antibodies that target the specific bacteria that you have over there. Clear. T and be good. And for the antibodies what you need to keep in mind these are like group of like glycoproteins. They have like those two chains the heavy chain and the light ones which are the red ones, as you can see over here. And they're variable domains that are found on both of those chains. And these changes based on what they recognize. And they target specific like bacterial antigen. So this is always different depending on what they target. And we have five classes of those immunoglobulins as we see the IgG and and E depending on how these small change I'm sorry I'm being defined by their heavy chains. If they're like the Alpha Gammas we said a E or Delta depending on their biologic role. And keeping in mind what the role of these antibodies are. So for example, the IgG, you will see that coming up again and again, because it's the main immunoglobulin that you will see in the blood, like 775% the IGA. It's like a localized protection in mucosal surfaces like even the saliva, the oral cavity, the IEM. You can find it in immature B cells connection with the complement. And usually it's the first antibody like immunoglobulin to take part in the immune response the IGD. You may find them on B cells as well. And finally the IgG it has a low concentration but it's increasing when you're usually having specific allergic reactions in the patients. So the neutrophils we talked about them again and again with the first line of defense. Again they comprise 50 to 70% of the leukocytes. They're critical to the host defense against an injury infection bacteria. As we said we can find them in acute lesions in large numbers. Again remember those phases of the page and shoulder. The first things first thing you have is neutrophils. And eventually when things become more chronic they go into plasma cells. Why. Because everything is being activated T cells B cells B cells bring the inflammation produce the antibodies. They bring them on the side. And that's why you find them there. They play a central role in the local tissue damage. And they're first localized into sites of infection. And finally the monocyte or macrophage they play a direct role in the cell mediated immunity. Its large foci cells the most important cells in the later stages of inflammation. And they are a key producer of inflammatory mediators with the cytokines, the prostaglandins, everything that plays a role in the boss, both hostile host cells and bacterial components. So if I ever ask you which one is the key cell, the answer is this one. The macrophage. It's big. It's where everything starts from. And it takes part both in the innate immunity and the adaptive immunity with antigen presentation, with phagocytosis, with elimination of optimized antigens and everything. As you see over here, a lot of things like with the macrophages, even with the inflammation, with modulation of the fluid, the cellular component, the tissue degradation, enzyme secretion, the prostaglandin, subsidization of antigens, the cytokines, everything that plays a role in the immunities like this key cell, the macrophage. And if we want to see like schematically what's what's happening as you see over here. So you're starting with the lysis of the gram negative bacteria which are being found, as we said, more prevalent in diseases in the present theories. And what are the LPs? As we talked about last time, the virulence factors and those things are being bound together. And that's where the macrophage comes into place. And it connects over here to activate the macrophage. So a lot of antibodies when they are being produced they try to inhibit that connection so that this cascade doesn't happen afterwards. Right. So you're having those the macrophage being activated. And then after that if this continues to be activated that's when you're having the signaling. We said in the previous slide with the cytokines as we're going to say that's why I have it here. A lot of host modulation agents are trying to target that time, that area over here to stop again the cascade that's happening afterwards. But eventually with those production of pro-inflammatory cytokines, we talked about those with the interleukins 186 etcetera, the tumor necrosis factor, the maps they activate, the coagulation pathway, the prostaglandins. Remember the Cox analogs pathway like six seven slides ago, the activation of the complement. And all of those things lead to the fibroblast activation, bone resorption and extracellular matrix destruction. That's how the whole cycle works okay. And since I mentioned the fibroblasts here, it's important to keep in mind that in health obviously it's something that we like because it produces the collagen the MMP inhibitors and leads to the connective tissue regeneration and repair. But in disease where things are being dysregulated, it leads to more production of MMP, which eventually lead to tissue destruction. So it's all about the balance between those two things. Okay. And everything that we said here I have it on that slide where you're having the help with the homeostasis and when you're starting having inflammation, either with the gingivitis here and eventually on Titus with a sub gingival, this biotic biofilm. So it's a biofilm that doesn't live well. You're having this inflammation production. And you're seeing here that the complement is being activated inflammatory cells. And eventually from those symbiotic which means I live well okay Greek words. By the end of this class you will all know Greek I'm pretty sure. Eventually leading to this biopsy which is live and, well, okay with inflammation and eventually Titus with a susceptible host. So that's how the transition goes from health to disease. Okay. As promised, I have a. AD for the compliment. Yeah. Don't get lost here, okay? I don't want you to get lost in that. It's a lot, I know. Just remember that you have two major pathways. The classic pathway, which is the antibody antigen complex in the alternative pathway and in terms of parts of the complement that may come up, are mainly those C three that you need to remember. Don't get lost with the rest of them. I have it here for your reference. But what you need to remember are the biologic effects of the complement, which is lysis, subsidization, activation of the inflammation of the inflammatory response and clearance of the immune complexes. So it's important I know it's a big chapter. I'm not going to go into much details with the complement. It's very advanced and everything, but I just need you to understand how everything works and how it's important. And a lot of studies also evaluate that because it plays a role in all those different categories over there. Okay. And I just have this here for your reference. Don't get lost with all those components of the complement. Just for your reference. If you want to understand more and read more in this one. And as promised, I have the clotting cascade. Yes, of course, because this plays a role. Again, don't get lost. I'm not going to ask you what the factor ten or factor 13 does on the clotting cascade. It's mainly also for your reference. I know you're all aiming about the final exams and everything. Yes, I get it. I'm not going to. Like argue on that. But on the other hand understanding what's happening, it's important for you to understand everything without meaning that I'm going to say, okay, tell me what the factor seven eight does in that area is not part of that, but just understanding how the impact of the clotting cascade plays a role in both the extrinsic intrinsic pathways in terms of preventing the infection, the inflammation, the infection, stopping the bleeding as a scaffold. And you will see that all these things will come into discussion when we will start with treatment, either surgical or surgical treatment, and why these are being important in order to understand how effective our treatments are and leading to all these things, you can see that. We talked about all these things over here almost. We have to talk about the bone metabolism. But so far we talked about everything like this over here. The host immune inflammatory response, the cytokines and everything, the maps. And now we're going to be leading to connective tissue in the bone metabolism on that side which is the osteo immunology. So. This can be very confusing. And I'm telling you, you have to read it again and again and again to understand what's happening there. But the easiest thing it can make it to for you to understand is that you need to understand that the ranking is a master switch, as we call regulator, and the osteoblasts express the ranking in their cell membrane. And then this ranking binds to rank. So without the L to this receptor and that activates the osteoclasts. And that's happening regularly in our body because our bone just has these metabolism and turnover all the time. Okay. So having said that, when enough bone is reserved and we don't need to have more resorption, we need to stop that somehow. Right? So that's when we're having the OPG which is also expressed by osteoblasts. That goes in blocks. This one the ranking. So it cannot connect to the rank. So that's we're saying okay enough bone is resolved. Now we need to bring back to bone homeostasis. That happens to everybody here. So all of us when these like rank low PG ratio changes and especially with inflammation increases like it happens in periodontitis. What happens is like a lot of frankly more radical that has the ability to bind to rank and then activate the osteoclasts and then bone resorption. If you don't have enough OPG to block that, that's when you're going to have it over there. And obviously these are concentrations are being controlled with by cytokines. And this is not going to start by itself. The whole cascade that we talked already about how the macrophage cytokines, all these MMP is everything that plays a role eventually lead to this dysregulation. Yes. Regulating both the activation and. And the opposite of the glass or just the activation of the. Yeah. So it actually what binds with what. So the rankle is being expressed by the osteoblasts. And it needs to bind to rank in order to activate the osteoclasts. As long as it bites as it binds over here and connects it activates the osteoclasts. If this doesn't stop for whatever reason, you will continue having bone resorption. So what you need to do is to stop this connection. And for this to not connect, you bind something else to the ankle, which is the OPG. So it binds over there in the OPG. So it cannot bank like bind to the wrong. So then eventually the osteoclasts are not being activated. So it stops. And then the osteoblasts play a role to form the new bone. Yeah. Can you repeat the parallel titles with the raincoat and the. Yes. So we have three things. So we have the ranking that's being expressed by the osteoblasts. And I have also a slide afterwards that can make more sense. You're having the ranking that's being expressed by the osteoblasts and say okay now we need to do some bone remodeling. So what do I need the help of the osteoclasts. How I'm going to activate them, I'm going to have the ranking that's going to bind to that receptor, the rank receptor. And this combination activates the osteoclasts. The osteoclasts will learn in our very first or second lecture it starts to reserve the bone. Right. So they start working over there. And remember that lacunae we talked about in the second lecture, that both of them are happening and orchestrated together. They started resolving the bone after the amount of bone that's wished is reserved for the normal remodeling. Then the osteoblasts express the OPG that goes and binds to that so that this cannot bind to that, so that these bone that things together cannot activate the osteoclasts. So what happens with periodontitis because you're having this inflammatory response and cascade. Remember we talked about the cells. We talked about the cytokines that are being activated with a complement and everything. All these tables and schematics that we showed about these produced more cytokines and these concentrations of how much Runkel and OPG are you're going to be producing or being regulated by those production. So apparently you're having more inflammation, more production of the radical is being more radical is being produced over there. So even if the poor osteoblasts produce, OPG is not enough to block all of that. So rankle still keeps connecting with rank and still leads to the bone resorption. So if you see over there, it's this imbalance that's happening over there. And that's why we say about the ratio. And again, a lot of studies evaluating some clinical things. They evaluate the ratio which means why doesn't increase. Because the top part of the ratio is getting higher compared to the lower part. Clear. Okay, I'll have a short video to maybe make it a little bit better for you. Osteoclasts are the specialized cells that restore bone, and osteoblasts are the cells that form new bone. The discovery of the rank ligand pathway has been an important advance in our understanding of bone remodeling. Rank ligand, a protein expressed by osteoblasts, plays a key role in osteoclasts formation, function and survival through interaction with its receptor rank that is expressed on the surface of osteoblasts. Osteo Proteger or OPG. Another protein secreted by osteoblasts is a natural inhibitor of Ranke ligand and plays a role in regulating bone resorption. At the initiation of bone remodeling, lining cells move apart to expose the bone surface, become osteoblasts, and begin expressing rank ligand. Rank ligand binds to rank on osteoclasts, precursors, which initiates cell fusion and the formation of mature multi nucleated osteoclasts. Rank ligand continues to bind to rank on mature osteoclasts. The binding of rank ligand to rank is essential for osteoclasts. Formation function and survival. Following bone resorption, osteoblasts migrate into the pit. Osteoblasts fill the pit with new bone matrix. Some osteoblasts become embedded within the matrix and eventually turn into osteocytes, while others become new lining cells on the bone surface. In the final stage of remodeling, newly created bone matrix mineralized and the bone returns to a resting state. Okay. Makes sense how the whole concept works. Have a question? Oh, okay. Good. So what we were saying right now with osteoclasts and osteoblasts and maybe this illustration will help you. You see, the blue one is the wrong that the orange actually first is the ranking that you see over here, those arrows that connect with the rung and activate the osteoclasts. And when you're having the OPG that goes in and block the Runkel, it cannot connect to the blue one. So this cannot happen. So what happens in pardon is with inflammation you start having like more of those rankle. You see those oranges and less of those OPG the red ones. So sure some may be blocked but a lot of them exist over here. So they connect to the rank and then activate the osteoclasts more and have more bone resorption. Good. Okay. And I know I've been talking for almost an hour by 30s. And that's everything that I've talked about today. So those slides, everything is here. So what happens? Like you see the tooth biofilm. Okay. You're having your pocket the LPs. Remember that we're having those cells that are playing a role with the defense cells with the connective tissue damage the osteoblasts. Everything with happens with the activation with the T cells, the B cells, the antibodies that are happening on that side leading to the bone resorption. So everything that I've been talking about, it's pretty much over there. So the whole mechanism why this works. Any questions? No. Yes. A good question. It's not necessarily the suppression. It's more like the overproduction of the rankle that even the existing OPG that is being produced by the osteoblasts, that's where they're both are being produced, cannot compensate to block them so that they can stop the resorption process. Anything else? Very good. Therapy. To increase the OPG? No. So this all have. Yes. Good question. So not specific therapy that will target in the OPG per se. What they target is that the with the host modulation treatments they try to stop the steps before reaching there. Because eventually this is the last part that's happening with the mental disease. Right before that we have the inflammatory response, the B cells, T cells, the cytokines and everything. So a lot of host in host modulation treatments are trying to block those pathways before you end up reaching over there stimulating the Runkel and changing the ratio. Nothing else. Okay, so I'm not done yet. So. Yes. No. Apart from me liking several things. One thing that I like are movies. So I want you to tell me which one is the best blockbuster movie of all time. A b c d e. Yeah. Titanic. Yeah. I know there's not going to be a consensus here because everything you're telling is wrong. I've watched all of them. They're amazing. The correct answer is E. Okay, because I'm going to show you now the best blockbuster movie of all times. Okay. I don't have popcorn. I'm sorry, but. You need to pay attention. Any living organism has to delineate the border between itself and the environment. Mario. Dental health is a continuing struggle to maintain an equilibrium between microbial attack and defense. Our body is completely protected by an ectoderm sheath that is interrupted only in one site at the tooth. Special mechanisms were developed in the course of evolution that protect the organism against intruders along the tooth. Exfoliation of junctional epithelial cells and a continuous flow of fluid removes contaminated cells and bacteria from the sulcus. Relevant components of the immune response are located in the gingiva. Something has changed. The gingival tissue is now swollen and red. Even the most careful probing causes bleeding. Different salivary proteins, including staghorn and Mucins, form a layer on the tooth surface. This pellicle facilitates the initial adhesion of bacteria. I, you know, my CS and streptococci are among the first colonizers. The bacteria form a sticky polysaccharide matrix that protects them from detachment and creates a distinct environment in which they proliferate and interact. The resulting differentiated three dimensional biofilm contains interconnecting channels and protects the bacteria from salivary components and antibacterial substances. In the biofilm. Bacteria compete for nutrients, exchange genes and signals, and proliferate. Not unlike buds. Vacuoles eventually open and release their contents. In the deeper layers, the bacterial flora shifts towards anaerobic, gram negative and pathogenic strains. The plaque prevents the inflow of the pellicle proteins that normally inhibit the crystallization of salivary mineral salts by keeping them in solution. Thus, calculus is formed. The sub gingival plaque grows in the depth of the sulcus. From here, bacteria and their products, such as lipopolysaccharide and toxins invade the adjacent tissues, but the body reacts. The innate immune system recognizes bacterial antigens and substances like formal methionine peptides as foreign intruders and initiates a spontaneous defense. The complement system is activated. A component of this system, the upside izing factor C3B, labels bacteria for facilitated phagocytosis. Complement factor C5B initiates the membrane attack complex that causes the bacterial cells to burst by forming pores. Defenses which are ring shaped host derived proteins operate in a similar manner. Meanwhile, bacterial lipopolysaccharide bind to lipopolysaccharide binding protein and are then recognized by toll like receptor four. In addition, endotoxins activate the complement system through the alternative pathway. C3A and C5A act on macrophages and neutrophils stimulating chemotaxis and triggering the release of proinflammatory cytokines. Messenger molecules called chemokines, cause the endothelial cells to loosen their intercellular contacts and to express adhesive proteins on the inner walls of the blood vessels. As a result, neutrophils adhere and migrate through gaps between the endothelial cells into the surrounding tissue. This process is called diabetes. They follow the concentration gradient of chemokines such as interleukin eight. This chemokine, also known as CL eight, is released by the epithelial cells and fibroblasts of the junctional epithelium. Once at the site of infection, the neutrophils kill the invading pathogens after phagocytosis and by releasing reactive oxygen and chlorine species. During the inflammatory reaction, the gingival connective tissue is loosened by shifting the balance between connective tissue protein synthesis and degradation. The responsible collagen degrading enzymes such as pepsin G are derived from decaying granulocytes or, like matrix metallo proteins, ate from macrophages or fibroblasts. The loss of structural integrity of the connective tissues. The dilatation of the vessels, the increased capillary permeability, and the ulceration of the cellular epithelium contribute to bleeding upon probing. If a new equilibrium between microbial attack and immune response is achieved, the gingival inflammation will persist as an established lesion. Otherwise, an advanced lesion will develop accompanied by further tissue breakdown and loss of attachment. Bone resorption follows loss of periodontal attachment and is an element of irreversible periodontal tissue destruction. Under normal circumstances, periodontal bone height remains stable as bone formation and bone degradation balance each other. The bone balance is maintained by coupling of the bone building cells, the osteoblasts, and the bone reforming cells, the osteoclasts. Osteoclasts. Precursor cells are derived from immunogenic monocytes, which migrate into the alveolar bone from surrounding blood vessels along a gradient of interleukin eight and interleukin one beta. Here they penetrate through the layer of bone lining cells. Bone lining cells present on their surface. Membrane bound rank ligand that activates the rank receptors on the osteoclasts. Precursors. Under the additional influence of monocyte colony stimulating factor, they merge into multi nucleated osteoclasts. What was originally part of the immune defense has now become a bone resource cell. The bone balance is controlled by the ratio of soluble osteoporotic gerren and rank L osteoporotic gerren masks the rank L and is released by osteoclasts under the control of various messengers, including vitamin D and hormones. Once the osteoclasts have completed their task, they attract neighboring osteoblasts by the Efron receptor ligand system and bone morphogenetic proteins in order to refill the resorption. Lacuna. The adaptive immune system is involved in the transition from gingivitis to periodontitis by interfering with the bone balance. Naive T lymphocytes become antigen specific by contact with antigen presenting intra in glial dendritic cells after repeated antigen exposure. Antigen specific T helper cells, the T one lymphocytes synthesize, amongst others, large amounts of new soluble rank L. This rank L leads to osteoclasts differentiation. This is mediated by interleukin 17 from T 17 cells. Another T helper cell subtype, the two cells produce interleukin four, five and ten, causing the stimulation of B lymphocytes, which transform into plasma cells and release immunoglobulins. Osteoclasts, precursors. Being originally immune cells, carry the osteoclasts associated receptor, which can be activated by immunoglobulins. Under continuing presence of bacterial antigens. Osteoclasts will amplify bone resorption through the synthesis of chemokines such as monocyte chemo attractant protein one and interleukin one beta. The viable biofilm is removed by supra and subject level root instrumentation, which can be accompanied by antiseptics, local and systemic chemo therapeutics. As a result, bacterial load is reduced and the equilibrium is shifted towards healing. If the inflammation is switched off in a highly regulated cellular communication process in which tissue inhibitors of metallo proteases like axons resolves and cytokine inhibitors are released. Fibroblast growth factor stimulates fibroblasts to crawl into the lesion and synthesize collagen and other extracellular matrix components. Vascular endothelial growth factor initiates angiogenesis. Where viable cement blasts are still present on the root surfaces, the periodontal ligament may regenerate and new attachment will be formed. Otherwise, the epithelium will grow in an apical direction and