Immunomodulators

1. Immunomodulators
PRESENTED BY
SARATHLAL KC
M PHARM PART 1
DEPT. OF PHARMACOLOGY

2. Contents
• Introduction
• Organ Rejection
• Methods of Immunosuppression
• Immunostimulants.
• Conclusion
• References

3. Introduction
• Immunomodulators are drugs which either suppress or stimulate
the immune system –
(Immunosuppressants and Immunostimulants)
• Have been in use for more than 50 years.
• begin with non specific corticosteroids, antimetabolites and
alkylating agents.
• Now the specific inhibitors of immune responses are available.

4. Transplantation
• The first successful transplant: 1954
kidney transplant between two identical twins.
• No immunosuppression was used.
• Currently, most organ transplantation occurs between unrelated
individuals.
• Donor and recipient tissues express different MHC molecules.
• Recipient immune cells can recognize this MHC (consider the
transplanted tissues as foreign. )
Richard and Ronald Herrick

5. Organ Rejection
Divided into three major phases according to the time of onset.
• Hyper acute
• Acute
• Chronic rejection
Caused by different mechanisms and are therefore treated
differently.

6. Hyper-acute Rejection
• mediated by preformed recipient antibodies against donor antigen.
• these antibodies are present in receiver at the time of organ
implantation.
• hyper acute rejection occurs immediately after reperfusion of the
transplanted organ.
• Can readily notice the changes within few minutes.

7. • The normal healthy, pink organ become cyanotic, mottled and
flaccid.
• This is by the compliment activation by the antibody, when it binds
to the endothelial cells of transplanted organ.
• Most commonly the recipients antibody reacts with blood group
antigens.
• Transplant from Matching blood group prevents the Hyper acute
Rejection

8. Acute rejection
 acute cellular rejection
 acute humoral rejection
Acute cellular
• Mediated by the cytotoxic T cells, leads to interstitial and vascular
damage.
• Seen in months after transplantation.
• Suppressing the T cells is effective at preventing the acute rejection.

9. Acute humoral rejection
• Recipients B cells become sensitized to donor antigens.
• Antibodies are produced within 7-10 days.
• Antibody responses directs to endothelial cells
(acute vascular rejection).

10. Chronic Rejection
• believed to be both humoral and cellular in nature.
• does not occur until months or years after transplantation.
• chronic inflammation caused, by the response of activated T cells
to donor antigen.
• Activated T cells release cytokines that recruit macrophages into
the graft.

11. • The macrophages induce chronic inflammation
• The chronic changes eventually lead to irreversible organ failure.
• effective treatment regimens are currently not available to
eliminate chronic rejection.

12. Auto-immunity
• when the body produces an immune response toward its own
tissue.
• failure to distinguish self tissues and foreign antigens.
• Result is chronic inflammation.
• Rheumatoid Arthritis, Crohns disease, Ulcerative colitis.

13. Immunosuppression
1. Inhibition of gene expression
2. cytotoxic agents.
3. Inhibition of lymphocyte signalling.
4. Cytokines inhibitors.
5. Depletion of specific immune cells.
6. Inhibition of co-stimulation
7. Blockade of cell adhesion
8. Inhibition of compliment activation

14. Inhibition of gene expression
Glucocorticoids
Steroid hormones, have broad anti inflammatory activity.
Binds with glucocorticoid receptor.
glucocorticoid - glucocorticoid receptor complex translocate to nucleus.
Binds to GREs in specific genes
Regulates the gene expression
down regulate the inflammatory mediators.
(IL1, IL4 TNFα etc.)
( glucocorticoid response elements)

15. Cytotoxic agents.
Used for both immunosuppression and antineoplastic chemotherapy.
 Antimetabolites
 Alkylating agents
Antimetabolites
• Are powerful immunosuppressant.
• No selectivity in immunosuppression
• Acts on both cell mediated and humoral mediated immunity.

16. • Azathioprine and Methotraxate are older drugs which affect all
rapidly dividing cells, and also damages the intestinal mucosa.
• Mycophenolyte mofetil and leflunamide are newer ones, having
less adverse effects.

17. Azathiprine/Aza
• Pro-drug of 6 mercapto purine.
• Which reacts with sulfhydryl compounds like glutathione.
• Which slow down the release of 6 mercapto purine.
• This favours immunosuppression
N
N
N
H
N
S
N
HN
NH2
HN
N
N
H
N
S
Glutathione
6mercaptopurineazathiprine

18. Methotraxate/MTX
• It provides anti-inflammatory action by increasing adenosine level.
• Adenosine is potent endogenous anti-inflammatory mediator.
• It inhibits neutrophil adhesion, phagocytosis, and super oxide
generation.
• MTX also causes apoptosis of activated CD4 and CD8 T cells

19. Mycophenolic Acid and Mycophenolate Mofetil/ MPA ,MMF
• inhibitor of IMPDH (inosine mono-phosphate dehydrogenase ).
• the rate-limiting enzyme in the formation of Guanosine
• MPA has low oral bioavailability, it is usually administered as a
sodium salt or in its prodrug form, mycophenolate mofetil (MMF).
• MPA and MMF both act on lymphocytes.
• lymphocytes are dependent on the de novo pathway of purine
synthesis, whereas most other cells rely heavily on the salvage
pathway.

20. • IMPDH is expressed in two isoforms,
type 1. IMPDH
type 2. IMPDH
MPA preferentially inhibits type 2 IMPDH, the isoform expressed mainly
in lymphocytes.
Reduces intracellular Guanosine levels
Elevates intracellular adenosine levels.

21. Leflunomide
• Leflunomide is an inhibitor of pyrimidine
synthesis.
• blocks the synthesis of uridylate mono
phosphate
N
H
O O
H+
H20
N
H
HN
O
O
O
O
NAD
NADH
dihydroorotate
dehydrogenase
N
HN
O
O
OH
HH
HH
OH
O
P
O
O
O
O
n carbamoylaspartate
dihydroorotate
leflunamide
UMP
FK778, metabolite of leflunomide
Astellas Pharma Inc, Europe

22. Alkylating Agents
Cyclophosphamide/Cy
• Highly toxic drug that alkylates DNA.
• Able to attach the nucleophilic sites on the DNA.
• Results in covalent attachment of an alkyl group.
• N7 or O6 atoms are the place of attachment.
• Guanosine base is more susceptible for alkylation.
Which form bis- alkylation.
• Leads to the cross linking of Guanosine residues – produces
cytotoxicity.

23. DNA anomalies caused by
• It cleaves the Guanosine imidazole ring,
• Produces abnormal base pairing,
• Depurination.
O
P
H
N
O
N
Cl
Cl
Cyclophosphamaide

24. Inhibition of Lymphocyte signalling.
Cyclosporine and Tacrolimus
• Cyclosporine/CsA discovered in 1976. (also referred to as Cyclosporin A )
• CsA is a cyclic decapeptide isolated from a soil fungus,
Tolypocladium inflatum.
• Specific inhibitor of T-cell-mediated immunity.
• It also inhibits the production of IL2 by activated T Cells.
• IL2 activates and proliferates further T cells.

25. Activated T cells produces IL2 via Dephosphorilation of NAFT
(nuclear factor activated T cell - a cytoplasmic transcription factor)
Calceneurin is needed for dephosphorilation
(Cytoplasmic Phosphatase)
Translocates to nucleus
Transcriptin of IL2 gene.
• Cyclosporine bind s to cyclophilin - binding protein.
• Tacrolimus binds to FKBP – FK binding protein.

26. (nuclear factor activated T cell)
ISA 247
Aurinia Pharmaceuticals
NCT00504543
Novartis Pharmaceuticals

27. Sirolimus (rapamycin)
• Obtained from bacteria Streptomyces hygroscopicus.
• Binds to FKBP,
• FKBP- sirolimus complex does not inhibit calcineurin.
• Instead it blocks IL2 receptor signalling required for T cell
proliferation.
• FKBP- sirolimus complex binds to molecular target of rapamycine
(mTOR)

28. • Which inhibits p70 - S6 kinase and PHAS-1 activity, which
responsible for translation.
• Thus mTOR inhibition causes cell division arrests at G1 phase.
molecular target of rapamycine

29. Cytokine Inhibition
• Cytokines are critical signalling mediators in immune
function.
• They are pleiotropic (they exert different effects depending
on the target cell)
• 4 types
1) TNFα Inhibitors, 2) IL12/IL23 p40 inhibitors ,
3) IL1 inhibitors. 4) Cytokine receptor antagonists.

30. • TNFα Inhibitors
Etanercept is links the extracellular, ligand-binding domain of
human TNF receptor.
• IL-12/IL-23 p40 Inhibitors
diffferntiation of naive T cells
heterodimer composed of p40 and p35 subunits
Ustekinumab that can binds to the p40 subunit.
• IL1 inhibitors
IL1 stimulates the production of IL6
enhances the expression of adhesion molecule
Anakinra - IL1 receptor antagonist
• Cytokine receptor antagonists
Alternative approach to block the action of inflammatory cytokines.
Tocilizumab administered for rheumatoid arthritis as i.v infusion for
very 4 weeks.

31. Depletion of specific immune cells.
Targeted antibody therapy can deplete the reactive immune cells.
Polyclonal antibodies
• ATG (anti thymocyte globulin) antibodies produced by injecting
human thymocyte into rabbit or horse.
• ATG targets all T cells and leads to profound lymphocyte depletion.
• it produce broad immunosuppression, and can predispose to
infections.
• Used for renal transplant rejection.

32. Monoclonal antibodies
OKT3 (Muromonab- CD3/anti CD3).
• Mouse monoclonal antibody against human CD3
• CD3 expressed in both CD4 and CD8
• Treatment with OKT3 depletes T cell, via antibody mediated
compliment activation.
• Used for renal transplant rejection
• Second line agent for CsA or Glucocorticoid failure.

33. Anti-CD20 mAb
Rituximab is a partially humanized anti-CD20 monoclonal
antibody. (CD20 expressed in all B cells.)
Anti-CD25 mAb
• Daclizumab and basiliximab are monoclonal antibodies
against CD25. ( have high affinity towards IL-2 receptor.)
• CD25 is expressed in activated T cells.
• It selectively targets T cells that have been activated by
an MHC-antigen
• T10B9.1A monoclonal antibody & (MedImmune LLC)
• FTY720 (Novartis phase III)

34. • MHC : Antigen : TCR interaction (signal 1)
• B7 : CD28 (signal 2)
• B7 - Abatacept complex prevents delivery of a costimulatory signal
and the T cell develops anergy
• Abatacept therapy down-regulats prolifertion & differentiation of T cells.
• Belatacept is a structural congener of Abatacept.
Fig 1
Fig 2
Inhibition of Co-stimulation

35. Blockade of Cell Adhesion
The recruitment and accumulation of inflammatory cells at sites of
inflammation is an essential element of autoimmune diseases
Alpha - 4 integrins are critical to immune-cell adhesion
Two types : α4β1 integrins (mediates immune-cell interactions with cells
expressing vascular cell adhesion molecule 1
(VCAM-1)
α4β7 integrins (mediates immune-cell binding to cells expressing
mucosal cell adhesion molecule 1 (MCAM-1)
Natalizumab is a monoclonal antibody act against α4 integrin that inhibits
immune cell interactions with cells expressing VCAM-1 or MCAM-1

36. Inhibition of Complement Activation
Provides innate immune responses
( by classical, alternative or lectin pathway)
Foreign bodies/antigen
activation of complement proteins (C3a , C3b)
activation of complement proteins C5
Membrane Attack Complex - MAC
(a multiprotein structure that can cause cell lysis)
Eculizumab is a humanized monoclonal antibody against C5,
(Responsible for activation and triggers assembly of the membrane attack complex.)

37. Immunostimulants
immunostimulatory drugs have been developed with applicability to
infection, immunodeficiency,
They works on cellular as well as humoral immune system or both
Levamisole:
• Levamisole was synthesized originally as an anthelmintic
• but it restores the depressed immune function of B lymphocytes,
T lymphocytes, monocytes and macrophages
• ADR: Flu-like symptoms, allergic manifestation, nausea and muscle pain.

38. Thalidomide:
• Increases TNFα in patients who are HIV-seropositive.
• But Decreases circulating TNFα in patients with erythema nodosm
leprosum
• suggested that the drug affects angiogenesis.
• Teratogenicity is an undesirable effect.
Isoprinosine:
• Isoprinosine is a complex of the pacetamidobenzoate salt of N,N-
dimethylamino-2- propanol and inosine (3:1 molar ratio)

39. Mechanism of action:
• Leads the production of cytokine such as IL-1, IL-2 and IFN-γ.
• Increases proliferation of lymphocytes.
• ADR: Minor CNS depressant, transient nausea and rise of uric acid
in serum and urine.

40. Immunisation
Vaccines and immunoglobulins (Rho Ig)
Bacillus Calmette-Guerin (BCG)
• Live culture of Bacillus Calmette-Guerin strain of Mycobacterium bovis.
• Induces granulomatous reaction at the site of administration.
Therapeutic uses:
• Treatment and prophylaxis of carcinoma of the urinary bladder,
• prophylaxis of primary and recurrent stage of papillary tumors
Adr : Hypersensitivity, shock, chills, fever, malaise,

41. Recombinant Cytokines
Interferon gamma-1b
a recombinant polypeptide that activates phagocytes
induces the generation of oxygen metabolites that are toxic to a number of
microorganisms.
Interferon beta-1a
166-amino acid recombinant glycoprotein
interferon beta-1b
165-amino acid recombinant glycoprotein
Both have antiviral and immunomodulatory properties

42. Conclusion
• Several approaches are available for the pharmacologic
suppression of immunity,
• ranging from the relatively low-specificity approaches to the more
specific cell-signalling inhibitors and antibody therapies.
• Novel ideas for the manipulation of the immune system are
emerging..
• microRNAs (miRNAs) have been shown to have important
regulatory roles in immunity,
• Immunostimulnts are used in immunodeficient people. And also to
improve the resistance to infection

43. References.
• Golan D.E, Tajshjian A.H, Armstrong E.J, Armstrong A.W, Principles of
pharmacology The pathophysiologic basis of drug therapy,3rd Edition,
Lippincott Wlliams & Wilkins,2012,790-806.
• Brunton LL, Lazo JS, Parker LK, Goodman & Gilman's The Pharmacological
Basis Of Therapeutics, 11th Ed., McGraw-Hill, 2006,1291-1306.
• Rang.H.P, Dale.M.M, Ritter.J.M, FlouerR.J, Pharmacology, Philadelphia,
Churchil livingstone-elsevier,2003,244-260
• Patil U.S, Jaydeokar A.V, Bandawane D.D, immunomodulators : a
pharmacological review, international journal of pharmacy and
pharmaceutical sciences, vol 4, suppl 1, 2012.
• http://www.pbs.org/wgbh/aso/databank/entries/dm54ki.html accessed
on 24/6/2014