1. 21. Immune mechanisms of inflammation (local and systemic reaction). 22. Physiological mechanisms of regulation of the immune system. Cytokines (classification according to the function). 23. Defence against extracellular pathogens Defence against intracellular Anti-viral defence. 26. Defence against multicellular parasites.

2. Inflammation

3. Inflammation
Is a physiological response of the organism to harmful stimuli, leading to localization of damage, elimination of pathogens, necrotic cells… and initiation tissue repairing.

4. Causes of inflammation
Physical injury
Infection by pathogens
Damage caused by chemicals
Cancer
Alergic disease
Autoimmune disease

5. Inflammation
Inflammation acute (physiological reactions, damaged tissue heals completely) chronic (usually pathological reactions, destruction of tissue and compensation with fibrous tissue) Response of the organism local systemic

6. Local body's response to inflammation Signs - pain (dolor), heat (calor), redness (rubor), swelling (tumor)

7. Local inflammation
The first signals for the development of inflammatory reactions originate from activated phagocytes, mast cells, complement and substances released from damaged cells and extracellular matrix components.

8. Local inflammation

9. Local inflammation
vasodilation and increased vascular permeability (histamine, serotonin, bradykinin, complement components C3a, C5a, leukotrienes, prostaglandins) => redness and swelling
increased expression of adhesion molecules on endothelial cells (TNF, IL-1) => capture leukocytes and phagocytes
influence nociceptors (prostaglandins, ...) => pain
Increase temperature (IL- 1, IL-6, TNF, prostaglandins)

10. Systemic inflammation
leukocytosis
fever (TNFa, IL-1, IL-6, IFN)
↑ tissue metabolism
↑ mobility of leukocytes
↑ IFN, cytokines and Ig production
↑ expression of Hsp
acute phase proteins (IL-6, TNF, IL-1)

11. Acute phase proteins produced by hepatocytes:
CRP - opsonization, complement activation
SAP - opsonization, complement activation
SAA - attracting leukocytes
C3, C4
protease inhibitors - protection against secondary tissue damage
serum transport proteins

12. Systemic inflammation
Septic shock - the massive penetration of microorganisms into the bloodstream (  TNF) Anaphylactic shock - basophil degranulation after contact with allergen (histamin)
Systemic inflammation

13. Repair of damaged tissue
after the elimination of pathogens and damaged cells by phagocytes
activation of angiogenesis
regeneration and tissue remodeling (fibroblasts, smooth muscle cells, keratinocytes, epithelial cells)
regulated by cytokines: PDGF, TGFb (platelets, macrophages ...)

14. Physiological regulation of the immune system

15. Physiological regulation of the immune system
Regulation by antigen
Regulation by antibodies
Regulation by cytokines and cellular contact
Suppression mediated by T cells
Other factors influencing the outcome of the immune response
Regulation by cytokines

16. Regulation by antigen Immune responses induction and extinction
Affinity maturation of B lymphocytes
Maintaining immunological memory
Antigenic competition
Threshold density of the complex MHC II-gp Ag on APC

17. Regulation by antibodies
Antibodies competes with the BCR for antigen (negative regulator of B lymphocyte stimulating)
IgG immune complexes bind to the BCR and FcgR on B cells, resulting in blocking of B cell activation
Regulation via idiotypic network

18. Regulation by cytokines and cellular contact
Interaction APC - T lymphocyte
Interaction TH1 – macrophages
Interaction TH2 - B lymphocytes
Mutual regulation of activity TH1 versus TH2
Development of leukocyte subpopulations Negative regulation of effector cells:
CTLA-4 - T cell inhibitory receptor, binds ligands CD80 and CD86
Inhibitory receptors of NK cells
Self-destruction interaction of the apoptotic receptor Fas with ligand FasL on the surface of activated T lymphocytes

19. Suppression mediated by T cells
Mutual negative interactions mediated by Th1 and Th2 cytokines (Th2 cells produce IL-4 and IL-10 which suppress the immune response, based on TH1 cells)
Clonal elimination or anergition of T cells after antigen recognition on the surface of other cells than APC (lacking co-stimulatory signals)
Regulatory T cells maintain tolerance to autoantigens (Treg, Tr1)

20. Factors influencing the outcome of the immune response
The same antigen can induce an active immune response or an active state of tolerance, the result of response depends on many factors:
State of the immune system
Properties of antigen
Dose of antigen
Route of antigen administration

21. Cytokines (Tissue hormones)

22. Cytokines
Regulatory proteins and glycoproteins produced by leukocytes and other cells
Essential regulators of the immune system
Apply outside the immune system (angiogenesis, tissue regeneration, carcinogenesis, treatment of many brain functions, embryonic development ...)
Cytokines - secreted      membrane (CD 80, CD86, CD40L, FasL ..)

23. Cytokines Pleiotropic effect Operates in a cascade Cytokine Network
Cytokine system is redundant
Effects of cytokines - autocrine paracrine endocrine
Are known as interleukins (exception: TNF, lymphotoxin, TGF, interferons, CSF and growth factors)

24. Distribution of cytokines by function
Proinflammatory cytokines (IL-1, IL-6,IL- 8,IL- 12,IL- 18, TNF)
Antiinflammatory cytokines (IL-4, IL-10, TGF)
Cytokines with the activity of hematopoietic cells growth factor (IL-2, 3, 4, 5, 6, 7, 9, 11, 14, 15, CSF, SCF, LIF, EPO)
Cytokines applying in TH2 humoral immunity (IL-4, 5, 9, 13)
Cytokines applying in the cell-mediated immunity TH1 (IL-2, 12, IFN, GM-CSF, lymphotoxin)
Cytokines with antiviral effect (IFN-, IFN-, IFN- )

25. Overview of the most important cytokines
Produced
Function
IL-1
MF, N
T cell costimulation, induction of TNF and IL-8, pyrogen
IL-2
Th1
Growth factor for T cells
IL-4
Th2, basophils
Th2 differentiation, B cell stimulation, isotype switching to IgE and IgG4, Th1 inhibition
IL-5
Th2, eosinophils
B cell stimulation, growth factor for eosinophils
IL-6
Th2, MF, N
T and B cell stimulation, stimulation of Ig production, induction of acute phase proteins synthesis, pyrogen
IL-8
MF, other cells
Granulocyte activation and chemotaxis (primarily neutrophils)
IL-10
Th2,M, Treg
Th1 and MF inhibition, B cell differentiation to plasma cell
IL-12
MF, DC, B
Th1 differentiation, NK stimulation
TNF
M, MF, NK
Induction of local inflammation, endothelium activation, induction of apoptosis
TGFb
T, MF, platelets
The anti-inflammatory effect (control of lymphocyte proliferation, control of Ig production, control MF activity), stimulation of fibroblasts and osteoblasts, gain production of extracellular matrix
IFNa
L, M, MF
Inhibition of viral replication
IFNb
Fibroblasts, epithelial cells
IFNg
Th1, NK
MF activation, stimulation of MHC gp. expression, Th2 inhibition
MF – macrophages; M – monocytes; N – neutrophils; DC – dendritic cells; NK – natural killers; L – lymphocytes; B – B cell; T – T cell

26. Cytokine receptors Consisting of 2 or 3 subunits
One subunit binds cytokine, other are associated with cytoplasmic signaling molecules (protein kinases)
Signaling subunit is shared by several different cytokine receptors - called receptor family
Signaling through these receptors may lead to proliferation, differentiation, activation of effector mechanisms or blocking the cell cycle and induction of apoptosis

27. Defense against extracellular pathogens

28. Defence against extracellular pathogens
bacteria (gram-negative, gram-positive cocci, bacilli), unicellular parasites
pathogens induce inflammation
removed by phagocytosis - neutrophil granulocytes
opsonization (IgG and IgA antibodies, C3b, lectins, CRP...)

29. Defence against extracellular pathogens Opsonisation and phagocytosis

30. Defence against extracellular pathogens
Phagocytes are attracted to the site of infection by chemotactic substances (C5a, C3a and chemotactic products of bacteria…)
ingested bacteria are destroyed by the microbicidal systems (products of NADP-H oxidase, hydrolytic enzymes and bactericidal substances in lysosomes)
phagocytes produce proinflammatory cytokines (IL-1, IL-6, TNF)

31. Defence against extracellular pathogens
IgM - complement activation
IgG - activation of complement, opsonization
IgA - opsonization sIgA prevents against infection by intestinal and respiratory bacteria
in the defense against bacterial toxins apply neutralizing antibodies (Clostridium tetani and botulinum …)

32. Defence against extracellular pathogens
"indirect toxins - bacterial Lipopolysaccharide (LPS) stimulates big number of monocytes to release TNF, which can cause septic shock
individuals with immunodeficiency of phagocytes, complement and antibodies production are especially at risk of infections with extracellular bacterial

33. Defense against intracellular pathogens

34. Defense against intracellular pathogens
bacteria, fungi and unicellular parasites
intracellular parasites are resistant to the microbicidal mechanisms of phagocytes
macrophages, which absorbed them, produce IL-12 → TH1 differentiation, production of IFNg and membrane TNF → activation of macrophages and production of NO

35. Defense against intracellular pathogens

36. Defense against intracellular pathogens
TC lymphocytes apply in the defense against intracelular parasites, which escape from phagolysosomes
individuals with certain disorders of phagocytes and defects of T lymphocytes are at risk of infections with intracellular microorganisms

37. Defense against intracellular pathogens

38. Anti-viral defense

39. Anti-viral defence
interferons - production of IFNa and IFNb is induced in infected cells; IFNg activates macrophages (iNOS)
IFNa and IFNb - prevents viral replication
- induce proliferation of NK cells
- increase the expression of HLA-I

40. Anti-viral defence - interferons

41. Anti-viral defence
NK cells - ADCC (Antibody-dependent cell-mediated cytotoxicity); NK cell bind with CD16 (Fcg receptor) to IgG which has bound to the surface of infected cell and then NK cell release perforins and granzymes (degranulation)
infected macrophages produce IL-12 (a strong activator of NK cells)

42. Anti-viral defence - NK cell activation
ADCC

43. Anti-viral defence
in the defense against cytopathic viruses applied antibodies:
sIgA inhibit mucosal adhesion of viruses (defense against respiratory viruses and enteroviruses)
neutralizing IgG and IgM antibodies activate the classical pathway of complement, that is able to lyse certain viruses
opsonized viral particles are phagocytosed
IgA and IgG have preventive effect in secondary viral infection

44. Anti-viral defence - antibodies

45. Anti-viral defence
effector TC lymphocytes destroy infected cells in direct contact (granzym/perforin; FasL) and by produced cytokines (lymfotoxin)
some viruses after infection integrate into the host genome, where persist for years (varicella zoster, EBV, papillomavirus)
individuals with T lymphocyte immunodeficiency and with combined immune disorders are at risk by viral infections
increased susceptibility to herpes infections in individuals with dysfunction of NK cells

46. Anti-viral defence – NK cells and Tc lymphocytes

47. Defense against multicellular parasites

48. Defense against multicellular parasites
IgE, mast cells, basophils and eosinophils
TH2 stimulation under the influence of IL-4 (mast cells and other APC stimulated by parasite)
TH2 stimulate B cells with BCR-specific parasite antigens
isotype switching under the influence of IL-4 to IgE
IgE bind to FceRI on mast cells and basophils

49. Defense against multicellular parasites
multicellular parasite binds to IgE on mast cell→ cross-linking of several molecules FcRI
initiate mast cell degranulation (release of histamin, tryptase, serotonin…)
activation of arachidonic acid metabolism (leukotriene C4, prostaglandin PGD2) - amplification of inflammatory responses
cytokine production by mast cell (TNF, TGF, IL-4, 5, 6)

50. Defense against multicellular parasites
Histamine
vasodilatation, increase vascular permeability (erythema, edema, itching)
bronchoconstriction (cough)
increases intestinal peristalsis (diarrhea)
increased mucus secretion This helps eliminate the parasite.

51. Mast cell activation

52. Defense against multicellular parasites
eosinophils fagocyte complexes of parasitic particles with IgE via their receptors for IgE
eosinophils use against parasites extracellular bactericidal substances released from granules (ECP- eosinophil cationic protein, MBP-major basic protein…)

53. Defense against multicellular parasites - eosinophils

54. Thank you for your attention