ORAL Immuno logy

1. ORALImmunology Faculty of Medicine/University Of Jordan April 9th 2015 Mohammed El-Khateeb

2. Outline • The Origin of Immune Concept • Overview of Immunity to Microbes • Features & Components of Innate & Adaptive Immunity • Hallmarks of the Immune Response • Self/Non-self Discrimination • Memory • Specificity

3. Figure 1-3 part 1 of 4 Blood Cells and their Precursors • Totipotent • Pluripotent • Multipotent • Unipotent

4. Figure 1-3 part 4 of 4 White Blood Cells (WBCs) Antigen Processing cells Immune Cells

5. Molecules

6. IMMUNE SYSTEM COMPNENTS Aaptive IS Innate IS Organs, RES Cell: Monocytes /Macrophages, PNL, Eosinophiles, Basophils, NK Molecules: Acute phase proteins, interferone, interleukins , kimokines • Organs: • Primary organs (Bone Marrow + Thymus) • Secondery organs ( LN, Spleen, MLAT) • Cells : B cells, T cells • Molecules: Igs, Lymphokine Cytokine

7. Innate (non-specific) immunity Adaptive (specific) immunity The immune system • Anatomic barriers (Skin,mucous membranes) • Physological barriers (temperature, pH) • Phagocytic Barriers (cells that eat invaders) • Inflammatory barriers (redness, swelling, heat and pain) • Antigen specificity • Diversity • Immunological memory • Self/nonself recognition

8. Innate and Adaptive Immunity • A summary of innate and acquired immunity INNATE IMMUNITY Rapid responses to a broad range of microbes ACQUIRED IMMUNITY Slower responses to specific microbes External defenses Internal defenses Skin Phagocytic cells Humoral response (antibodies) Mucous membranes Antimicrobial proteins Secretions Inflammatory response Cell-mediated response (cytotoxic lymphocytes) Invading microbes (pathogens) Natural killer cells

10. Figure 2-2 part 2 of 2

11. Figure 2-1 part 2 of 2 Three-phase Response to Initial Infection 0 – 4 hours 4 - 96 hours Late > 96 hours

12. RESPONSES • Activation of Complement • Activation of Acute Phase Proteins • Activate Phagocytosis

13. C’

14. Antiproteases α1-Protease inhibitor α1-Antichymotrypsin (ACT) Pancreatic secretory trypsin inhibitor Inter- α-trypsin inhibitor Tranport proteins Ceroloplasmin Haptoglobin Hemopexin Inflammatory response Phopholipase A2 Lipopolysaccharide-binding protein Interleukin-1-receptor antogonist Granulocyte colony-stimulating factor Others C-reactive protein Serum amyloid A Human Acute Phase Protein

15. Phagocytosis Phagocytosis

16. Immune cell Receptors Ig TCR

18. Overview of the stages of lymphocyte development and function Antigen Indpendeny Development Antigen Dependent Responses

19. Functions of Antibodies Functions of T-Cells After activation the cell divides to form: T-helper cells – secrete CYTOKINES  help B cells divide  stimulate macrophages Cytotoxic T cells (killer T cells)  Kill body cells displaying antigen Memory T cells  remain in body B- Cells:  Plasma cell Abs  Memory B cells

20. Dynamics of Adaptive Immunity This chapter tries to integrate much of what we have already covered so we can better understand how the immune system protects from infection. • How infectious agents cause disease • The course of an adaptive immune response • Immunological memory

21. Mucosal Immune System

22. Introduction • Mucosal Defence • Mucosal Immune system • Antigen - induced expansion of lymphoid tissue • Lymphocyte homing • Functional and phenotypic diversity • Regulatory T cells • Immunoglobulin IgA • Immunity thru’ Vaccination

23. COMPONENTS OF THE MUCOSAASSOCIATEDLYMPHOID TISSUE • Gastrointestinal tract (GALT) • Bronchial Tree (BALT) • Nasopharyngeal area (NALT) • Mammary gland • Salivary and lacrimal glands • Genitourinary organs • Inner ear

24. Mucosal NALT BALT GALT RALT *** # *** # *** The secondary lymphoid organs can be sub-divided into the Systemic (***) and Mucosalimmune systems

25. Tonsillar Tissues form a ring around entrance to GI tract

26. Mucosal Immune System • Immune response • Induction & Expression within same system • Mucosal Lymphocytes • Remain within the mucosal immune system • Lymphocyte migration / homing / retention • Special T cells • CD8 α/β, γ/λ , and regulatory T cells • Th17 cells Produce IL-17

27. Examples of mucosal diseases- role for Th17 cells • Gut: IBD – autoimmune diseases of the gut • Vaginal mucosa:Th17 cells are protective against Neisseria gonnorrheae • Lung: Th17 cells are protective against various pneumoniaes, TB, etc., promote airway hyperreactivity/allergy • Mouth: Th17 cells promote Sjogren’s (autoimmune disease of salivary gland, tear ducts), but protective in oropharyngeal candidiasis (“thrush”)

28. Mouth Contains organisms that survive mechanical removal by adhering to gums and teeth • Excellent growth environment with water, nutrients, temperature, etc. • Both aerobes and anaerobes present (biofilms) • Streptococci, especially S. mutans attach to enamel by glycocalyx • Contribute to formation of dental plaque, dental caries, gingivitis, and periodontal disease

29. Mucosa • The intact oral mucosa is a barrier against infecting organisms. • Superficial squamous cells may be colonized with bacteria in the same way as squamous cells on the skin, • Intact bacteria can cross a damaged epithelial barrier. • The undamaged oral mucosa is permeable to a range of substances smaller than bacteria

30. Oral mucosal secretions • Mucin • Lysozyme • Lactoferrin • Salivary peroxidase • Histatins • PRPs • Statherin • Cystatins • Epithelial cell derived antimicrobial peptides

31. Saliva • Saliva is a dynamic barrier in the mouth, constantly flowing backwards to the oesophagus. • Micro-organisms become entrapped and are carried via the oesophagus to the hydrochloric acid and pepsin of the stomach. • Saliva also acts as an additional barrier to the penetration of materials into the oral mucosa.

32. Saliva • Saliva contains a number of materials which afford non-specific protection to the individual. • Lysozyme, a mucolytic enzyme: is capable of splitting sugars off the glycopeptides of the cell wall of many Gram-positive bacteria, leading to their lysis. • Lactoferrin, which reduces the amount of free iron available for bacterial metabolism, • Unidentified basic polypeptides, which exert antimicrobial activity, • Lactoperoxidase which can cross-link proteins and hence damage certain bacteria and viruses. • Mucins : have some carbohydrate side chains in common with epithelial cells and competitively inhibit the binding of viruses to the epithelial cells

33. Salivary constituents and their functions defensins defensins Mucins defensins

34. Gingival Crevice • Since the gingival crevice may harbor micro-organisms and their products, the ability of the junctional epithelium to withstand penetration may be of considerable importance. • The junctional epithelium is apparently more permeable than other non-keratinized oral mucosa. • The flow of fluid is increased with gingival inflammation. • The major immunoglobulin classes are represented in gingival crevice fluid.

35. Cellular Components The cells involved in the immune response in the mouth are widely distributed in the following sites, • Submucosal tissue • Gingiva, • Salivary glands, • Epithelium, • Gingival crevice fluid, • Tonsils, • Extra oral lymph nodes, which drain lymph from the oral cavity

36. Oral Tolerance • Oral tolerance is • A general immunosuppressive state in the oral mucosa to prevent reaction to harmless Ags such as commensals or foods • the generation of systemic immune unresponsiveness by feeding of antigen • Necessary to prevent excessive response to normal flora and food antigens

38. Limitations to Oral Tolerance • Can be overcome with mucosal adjuvant (e.g. Cholera toxin) • Alter physical characteristics of antigen: antigen in micro-spheres that target PP • Feeding of attenuated enteric pathogen expressing the antigen (Salmonella)

39. Oral Antigen Induces IgA • Ingestion of killed Streptococcus mutans • IgA antibody producing cells • Peripheral blood by day 7, peak day 10 – 12 • Secretory IgA antibodies • Saliva & Tears by 2 weeks, peak 3 weeks

40. Natural development of sIgA • At birth: no sIgA in saliva • Predentate infants (16-28 wks): • Detected against “1st wave” of strep. organisms: S. mitis, S. salivarius (Smith and Taubman, 1992) • These organisms initially colonize mucosal surfaces • No Abs to S. mutans detected • Dentate children: • Tooth eruption brings “2nd wave” of strep. organisms: S. sanguis, S. mutans • Antibodies (Abs) against S. mutans observed in 1 yr old children • Abs against: serotype specific carbohydrate, protein I/II, glucosyltransferase, glucans, teichoic acids • w/i 10 yrs the child has IgA levels comparable to an adult (adult parotid saliva contains 30-160 g/ml IgA)

41. Major salivary glands produce 70% of total salivary sIgA • 30% comes from minor salivary glands • sIgA system is what we attempt to manipulate to prevent dental caries and certain microbial infections • 3 X as much IgA is produced/day than IgG • ~2/3 of IgA produced is sIgA • Primary function to prevent microbial adherence • Bacterial IgA-specific proteases found in S. sanguis; periodontal pathogens. (serum) sIgA

42. Secretory IgA - Production • IgA in blood is monomeric, >90% IgA1 • Secretory IgA • polymeric, IgA1 upper respiratory & GI tract IgA2 in colon &rectum • Induction by antigen in Peyer’s patches • Production by IgA plasma cells in lamina propria • J chain polymerisation of IgA • Binds polymeric Ig-receptor for trans-epithelial transport, cleaved to release secretory IgA

43. Secretory IgA - Function • Specificity • 2 – 5% reacts with specific Ag after immunisation • Commensal flora? Dietary antigens? • Resists proteolysis • Inhibits microbial adherence • Neutralisation of viruses, toxins (cholera) • Activates complement (alternative pathway) • Antigen exclusion • Modulation of enzyme activity

44. Possible Causes of Immunologically Mediated Mucosal Damage • Antigens:Local microbial flora or food • Accumulation of cirvulating antigen • B cell mitogens: Microorganisms and food • Mitogenic complement split products • Blastogenic factors from locally activated T and B cells • Lymphostimulatory factors from macrophages and neutophils • Altered autologous IgG-Immune complexes • Endogenous tissue antigens cross-reacting with microbial componenets

45. IgA Multiple Properties Adopted to GI Tract • Relatively resistant to proteolytic effect (IgA2>IgA1) • Poor activator of complement • Inhibits: • Bacterial adhesion • Macromolecule absorption • Inflammatory affects of other immunoglobulins • Neutralizes Viruses and Toxins • Enhances nonspecific defense mechanisms • Lectofernin • Lactoperoxidase • Mediate antibody dependent cytotoxicity (ADCC)

46. CF mainly derived from tissue fluids in blood capillaries It flows into the lamina propria through the JE and into the GCF Passes into saliva at the rate of 0.3 /tooth/hr Origin and Flow of Cervicular Fluid

47. SPECIFIC ORAL DISEASES • Dental Carries • Peridontal Disease • Aphthous Ulceration • Oral menifestations of Systemic Immunological Diseases

48. Mutans streptococci • Group of strep species most closely associated with caries of smooth surfaces, pits, fissures • 6 serotypes of ms that are associated with man • S. mutans serotype C, predominant group associated with enamel surfaces; 80-87% of cases in U.S. • Swedish kids; smooth surface caries, 36% presence of serotype c, 54% serotype d/g

49. Specific immunity against DCs • Caries correlated with sIgA titers and serum IgM to S. mutans. • Elevation in titer is due to exposure • Are these antibodies protective?? • Association between sIgA antibodies and resistance to dental infection by S. mutans has still to be convincingly demonstrated.

50. Serum Abs to Strp. mutans in Man DMF: Index of decayed, missing or filled tooth Active: High DMF group with one or more carious lesion