Innate Immune Systems PDF

Host Pathogen interactions Innate Immune systems  Terminology Susceptibility Lack of resistance to a disease Resistance Ability to ward off disease Nonspecific resistance Defens...

Host Pathogen interactions Innate Immune systems  Terminology Susceptibility Lack of resistance to a disease Resistance Ability to ward off disease Nonspecific resistance Defenses against any pathogen Specific resistance Immunity, resistance to a specific pathogen Mechanisms of Pathogenicity Pathogenicity is the ability to cause disease Figure 15.9  Host Defense Mechanisms Defense mechanisms two broad groups – Innate or Non-specific Immunity – Adaptive or Specific Immunity Non-specific – Protect against most any disease agent – Variable Stress Age Diet  Host Defenses Complement Barriers and chemicals Receptors for Pathogen Specialized Cells: Recognition: Antigen or shape recognition TOLL-Like “learned” or adaptive Complement Intercellular – Humoral Pattern recognition Intracellular – Cellular Figure 16.1  Immune System Flow Preformed Induced Antimicrobials Microbiota Barriers  First Line of Defense Physical barriers – Skin is most visible barrier – Covers majority of surfaces – Mucous membranes digestive tract respiratory tract genitourinary tract Skin, not just a covering for the juicy bits… – Provides the most difficult barrier to penetrate – Composed of two main layers Dermis – Contains tightly woven fibrous connective tissues » Makes extremely tough Epidermis – Composed of many layers of epithelial cells » As cells reach surface, they become increasingly flat – Outermost sheets of cells embedded with keratin » Makes skin water-repellent – Outer layers slough off taking microbes with it  Other Factors Mucous membranes and Secretions – Ciliary escalator: Microbes trapped in mucus are transported away from the lungs – Lacrimal apparatus: Washes eye – Saliva: Washes microbes off – Urine: Flows out – Vaginal secretions: Flow out – Defecation and vomiting  Normal Microbiota and the Host Microbial antagonism is a competition between microbes. Normal microbiota protect the host by: – Occupying niches that pathogens might occupy – Producing acids – Producing bacteriocins (Probiotics are live microbes applied to or ingested into the body, intended to exert a beneficial effect).  Normal Microbiota and the Host Transient microbiota may be present for days, weeks, or months. Normal microbiota permanently colonize the host. Symbiosis is the relationship between normal microbiota and the host. Figure 14.1c  Symbiosis In commensalism, one organism is benefited and the other is unaffected. In mutualism, both organisms benefit. In parasitism, one organism is benefited at the expense of the other. – Some normal microbiota are opportunistic pathogens. Representative Normal Microbiota Figure 14.1  Infection- a condition in which pathogenic microbes penetrate host defenses, enter tissues & multiply Disease – any deviation from health, disruption of a tissue or organ caused by microbes or their products  Who are these guys? includes bacteria, fungi, protozoa, viruses and arthropods Mosty in contact with the outside environment – large intestine has the highest numbers of bacteria internal organs & tissues & fluids are microbe- free – Presence of microbes indicate an infection  Physiological Barriers: Second line defenses Blood elements – PAMP recognition – Phagocytes – Complement proteins Inflammation response – Role of Inflammation Contain Damage Localize the response Restore function How to cells “see” pathogens? Receptors recognize shapes or patterns = PAMPs http://www.sabiosciences.com/pathwaymagazine/img/pathways7/page2b.jpg Innate Defense Phagocytosis Proteins in Blood part of “complement system” Recognition  Overview of Innate Defenses – Complement System – Acts in response to stimuli Activation sets off chain reaction that results in destruction or removal of invader The Complement System Figure 16.9 Effects of Complement Activation Opsonization or immune adherence: Enhanced phagocytosis Membrane attack complex: Cytolysis Attract phagocytes Figure 16.10 Complement membrane channel or MAC https://classconnection.s3.amazonaws.com/830/flashcards/1208830/png/screen_shot_2012-05-23_at_122743_am1337747276573.png  Next Time Adaptive Immune system