Biotechnology and Health (Prevention, Diagnosis and Treatment) PDF

Zarqa University Pharmacy school Department of Pharmaceutical sciences Pharmaceutical Biotechnology Biotechnology and Health (Prevention, diagnosis and treatment ) Dr. Shatha Alomari Role of biotechnology in developing vaccine A vacci...

Zarqa University Pharmacy school Department of Pharmaceutical sciences Pharmaceutical Biotechnology Biotechnology and Health (Prevention, diagnosis and treatment ) Dr. Shatha Alomari Role of biotechnology in developing vaccine A vaccine is a safe biological preparation, administered to humans to make them immune against a particular disease. The immune system of the human body identifies the vaccine as a foreign particle and destroys it, but the memory of the foreign matter remains intact with the virulent form of the disease causing organism, the immune system immediately recognises it and fight against the infection by releasing antibodies. There are several possible ways to develop a vaccine and it depends upon the procedure of infection by disease-causing microbes, the response of the immune system, the target site of the vaccine and the different physical characteristics of the microbe The various approaches are as follows: 1. Live, attenuated vaccines These types of vaccines comprise attenuated form of a disease causing microbe, so that it can no longer cause disease but only stimulate the immune system to memorize it. Rarely, the weakened microbe can revert back to its virulent form. The initial virus population is applied to a foreign host. One or more of these will possess a mutation that enables it to infect the new host. These mutations will spread, as the mutations allow the virus to grow well in the new host; the result is a population that is significantly different from the initial population, and thus will not grow well in the original host when it is re-introduced (hence is "attenuated"). This process is known as "passage" in which the virus becomes so well adapted to the foreign host that it is no longer harmful to the vaccinated subject. This makes it easier for the host's immune system to eliminate the agent and create the immunological memory cells which will likely protect the patient if they are infected with a similar version of the virus in "the wild". For example, influenza vaccine is prepared by passaging the influenza virus in embryonated chick eggs for an extended period 2. Inactivated vaccines (or killed vaccine) Is a vaccine consisting of virus particles, bacteria, or other pathogens that have been grown in culture and then killed using a method such as heat or formaldehyde. 3. Toxoid vaccines To combat diseases like tetanus and diphtheria caused by toxin secreting bacteria, these vaccines is made by exposing the toxin to formalin and making the toxin harmless. The immune system releases antibodies against the toxin which bind and block the action of toxins. 4. Subunit vaccines These vaccines contain only the antigens of disease-causing microbe and not the entire microbe. Evidently, antigens induce the immune system the most. Antigens are recognised and bound by the T cells of the immune system. Using recombinant DNA technology antigens can be made from the microbes in the laboratory. Such vaccines are referred as combining subunit vaccine. 5. DNA vaccines In DNA vaccines, when the genes that code for the antigens of that microbe are introduced into the body cells they initiate the body cells to generate antigens. As a result, the antigens stimulate the immune response of the body. These vaccines are easily producible and storable. 7. Recombinant vector vaccines Functionally similar to DNA vaccines, recombinant vector vaccines use a different method to introduce itself. The vector, either an attenuated bacterium or virus, is used to carry the DNA of the microbe into the body of the patient and infects it followed by delivering the DNA to the body cells. Research is in progress to develop bacterium-based and viral-based recombinant vector vaccines against HIV and measles Role of biotechnology in diagnostics Biotechnology has a vital role to play in present diagnostic sciences. The modern knowledge of DNA and its genes can examine the DNA of a person for following aspects: · Prenatal diagnostic screening for diseases viz. Down syndrome · Screening of carriers: the unaffected individuals are identified for carrying one copy of a gene for a disease, which actually requires two copies of a gene to produce the symptom, for example haemophilia and Tay Sachs disease · Estimation of the risk for development of adult-onset cancers by presymptomatic testing: for example a mutation in the BRCA1 gene in a person has a high risk of developing breast cancer · Prediction of adult onset disorders by presymptomatic testing: for familial high blood cholesterol  For diagnostic DNA testing, two techniques are generally used. The first technique involves comparing the sequence of bases in the gene of the patient to that of a healthy individual and in the second technique short pieces of DNA i.e. probes are used that consist sequences complementary to suspected mutations. These probes search for the complementary sequences among the patient’s DNA, then bind to it and flag or mark it Role of biotechnology in therapeutics  Biotechnology proposes a major avenue to developed therapies and treatments.  The development and usage of biotechnology techniques have enabled us to define the structure of DNA as well as the coded message hidden in the gene of DNA..  It has been discovered that faulty genes cause few diseases of the human body. The known genes for causing specific diseases can be used as targets to develop designed treatments for those diseases. Since the genes causing the disease is known, the finding of the treatment becomes cheaper and easier. The conventional pharmaceuticals are not able to reach these gene targets.  Another major reason is the large biological molecules like synthetic insulin for which biotechnology is being used. It cannot be manufactured in a traditional chemistry laboratory. Synthetic insulin can only be synthesized by living cells using biotechnological techniques. There are other large molecules also, produced by the means of biotechnology. For example, blood clotting factors for haemophiliacs, human growth hormone, fertility drugs etc.  Role of biotechnology in therapeutics Biotechnology helps in the development of treatments to cure diseases in mainly two ways: Pharmacogenomics. Gene therapy Human Genome is Variable Contains 3x109 base pairs of DNA – 3 billion! Between 2 people (except identical twins) the rate of genetic variation (individuality) is about 0.1% [0.1% of 3 billion = 3 million base pair differences]  The variations in the DNA have a name, they are called Single Nucleotide Polymorphism Single Nucleotide Polymorphism Polymorphism “Poly” Many “Morphe” Form The most common cause of General Population 94% genetic variation SNPs occur on average every 1000 bases Understanding SNPs has shown promise for improving disease detection and treatments Single Nucleotide Polymorphism 6% Single Nucleotide Polymorphism Polymorphism “Poly” Many The term polymorphism can be broken “Morphe” Form down into the root words for “many” General Population 94% and “form.” SNPs occur…In the diagram the general population may have a G at a certain point in the DNA sequence, but 6% of the population has a SNP at this location. In order for a SNP to be called a SNP must have occurred in ≥1% of population. Therefore, 6% indicates the SNP is authentic Single Nucleotide Polymorphism 6% Examples of SNPs and Disease Sickle Cell Anemia In sickle cell anemia, a SNP in B-globin causes the cell to be unable to carry oxygen properly. SNPs in BRCA1 Predisposed for breast cancer BRCA1 is a human tumor suppressor gene, responsible for repairing DNA. Having a SNP in BRCA1 doesn’t cause cancer. However, the SNP causes a loss of the ability for the cell to be protected form environmental risks that may contribute to breast cancer SNPs Can Change Drug Response Pharmacokinetic: Changes in drug metabolism Pharmacodynamic: Changes in drug targets enzymes, receptors, or transporters Genetic Polymorphisms Pharmacokinetic Pharmacodynamic Absorption Distribution Metabolism Excretion Receptors Ion Channels Enzymes Immune System SNPs Can Change Drug Response If we have SNPs and take a drug, we can have different things happen. Let’s look at the pharmacokinetic side of the story. Pharmacokinetics involves changes in drug metabolism, or what the body does to process a drug. If you had SNPs in metabolizing enzymes, what would it do to the drug? Genetic Polymorphisms Pharmacokinetic Pharmacodynamic Absorption Distribution Metabolism Excretion Receptors Ion Channels Enzymes Immune System SNPs and CYPs CYPs (or Cytochrome P450 genes) produce enzymes involved in the metabolism of molecules, including drugs, and are subdivided into groups and subfamilies (CYP3A4, CYP2C9, etc). These enzymes are mostly found in the liver, but they are also found throughout the body (brain, intestine, etc). Cytochrome P450 enzymes are commonly found with SNPs Drug Metabolism Polymorphism Substrate CYP2B6 doxorubicin, nicotine CYP2C9 warfarin, doxorubicin CYP2C19 diazepam, proton pump inhibitors CYP2D6 beta-blockers, anti-depressants, codeine, tamoxifen CYP3A4 erythromycin, HIV protease inhibitors Variation in drug response is hereditary Variations in absorption rates Variations in drug metabolism Variations in drug inactivation/elimination Variation in target receptors What is pharmacogenomics? Pharmacogenomics is the use genomic and sequence data of host and pathogens to identify potential drug targets Involves a variety of techniques/disciplines such as sequence analysis, protein structure, genomics, micorarray analysis and others These fields rely heavily on bioinformatics (biological studies that use computer programming) Usually focuses on medical or agricultural applications Pharmacogenomics Will allow: individualized medication use based on genetically determined variation in effects and side effects use of medications otherwise rejected because of side effects More accurate methods of determining appropriate dosage Why is this a good approach? Drugs can be dangerous Many people have severe adverse reactions to drugs Many people respond to drugs at different doses Many drug treatments are horribly unpleasant, painful Drugs are expensive (to take and to make) Ineffective drugs are a waste of money to take Drug development needs to account for response variability Genetics provide a priori information Genetics don’t change (except in cancer) Genetics can point to the cause not just the symptom Personalized Medicine The right dose of the right drug for the right indication for the right patient at the right time. Back to the drugs… The utility of pharmacogenetics: Determining appropriate dosing Avoiding unnecessary toxic treatments Ensuring maximal efficacy Reducing adverse side effects Developing or choosing novel treatments Can also explain variable response to illicit drugs Warfarin: A dosage story Most widely used anticoagulant in the world A “blood thinner” Prescribed doses vary widely (1- 40mg / daily) Therapuetic index is very low High risk of bleeding early in treatment Two genes involved in metabolism: CYP2C9 and VKORC1 (vitamin K epoxide reductase complex)  Warfarin Metabolism Two polymorphic genes, CYP2C9 and VKORC1, affect warfarin metabolism and response. Allelic frequencies of these two genes are usually associated with ethnicity. The Warfarin sensitivity DNA test determines the presence of specific variations in the CYP2C9 and VKORC1 genes that confer sensitivity to warfarin and thus significantly reduce the required maintenance dose Here are the concerns with prescribing warfarin to patients with CYP2C9 or VKORC1 polymorphisms: Overdose can result in bleeding which can be fatal. Under dose can result in thrombosis which can be fatal VKORC1 (vitamin K epoxide reductase complex subunit 1) This enzymatic protein complex is responsible for reducing vitamin K 2,3-epoxide to its active form, which is important for effective clotting. In humans, mutations in this gene can be associated with deficiencies in vitamin-K-dependent clotting factors. Warfarin causes inhibition on VKORC1 activities and leads to a reduced amount of vitamin K available to serve as a cofactor for clotting proteins. Inappropriate dosing of warfarin has been associated with a substantial risk of both major and minor hemorrhage. As the pharmacological target of warfarin, VKORC1 is considered a candidate gene for the variability in warfarin response. Frequency of VKORC1 Alleles in Various Populations VKORC1 polymorphisms may explain up to 25% of patient variability in response to warfarin. Patients with VKORC1A polymorphisms are at risk for exaggerated anticoagulant response CYP2C9 variants take more time to achieve stable dosing, and are associated with increased risk of bleeding events. Low CYP2C9 activity results in higher plasma levels of warfarin so the patient is at risk for bleeding Pharmacogenomics will most likely use “panels” of polymorphisms to calculate the relative risk–benefit ratio of a particular therapeutic course for an individual patient Pharmacogenetics and Pharmacogenomics Summary 1. SNPs in coding and non-coding regions can alter the function or expression of an enzyme that metabolizes drugs 2. Pharmacogenetics impacts the kinetics and dynamics of drugs. 3. Personalized medicine will help treat patients according to their genetic profile, increase drug efficacy, and reduce side effects 4. Designing clinical trials based on SNP profiles can reduce FDA approval time for drugs Pharmacogenomics