IMMUNOPHARMACOLOGY

Bashir Alsiddiq yousef

Review*2 major components of the immune system:

-INNATEPhysical – skin, mucus membraneBiochemical – complement, lyzosymeCellular – macrophages, neutrophils

-ADAPTIVEAntibodies – HUMORAL immunityT-lymphocyte – CELL MEDIATED immunity

Macrophage

APC

T lymphocyte

IL-2 IL-2

IFN-

Activated

MacrophageActivated

NK cells

Activated

Cytotoxic T cell

CELL-MEDIATED IMMUNITY

B lymphocyte

IL-4,IL-5

TH1

TH2

Memory B Cells

Plasma Cells:

-IgG - IgM

- IgA - IgD

HUMORAL IMMUNITY

IFN-

TNF-IFN-

Abnormal immune response

Hypersensitivity

Autoimmune diseases

Immunodeficiency

Types of Drugs

*Immunosuppressants

*Immunostimulants

*Immunomodulators

Immunosuppressants

Major Steps in Immune Responses

1- Antigen recognition2- IL-1 production3- IL-2 and other cytokine expression4- lymphocyte proliferation &

differentiation

Antigen

antigenpresenting cell (macrophage,dendritic cell)

CD4T helpercell

primedCD4T helpercell

CD8 T cell

cytotoxicT cells

plasmacells

1

2 3

4

4

IL-1 IL-2

IL-2

IL-2

MAJOR STEPS IN IMMUNE RESPONSES

B cell

Antigen

antigenpresenting cell

CD4T helpercell

primedCD4T helpercell

CD8 T cell

cytotoxicT cells

plasmacells

IL-1 IL-2

IL-2

cytokines

SITES OF ACTION OF IMMUNOSUPPRESSIVE DRUGS

X

X

X X

X

X

Immunosuppressants1. Corticosteroids2. Cyclosporine3. Tacrolimus4. Sirolimus5. Antimetabolites6. Antibodies7. Mycophenolate mofetil8. TNF-alpha binding drugs9. 15-Deoxyspergualin10.Thalidomide

Clinical uses

*Prevention of organ transplant rejection*Treatment of autoimmune diseases

-Multiple Sclerosis-SLE-Rheumatoid Arthritis-Crohn’s Disease

*Treatment of allergic reactions like Bronchial asthma and Eczema.

(Steps 1 and 2 - T cell activation and IL2 production):

Calcineurin

NFAT = Nuclear Factor of Activated T cells

IL-2 mRNA

IL-2 Protein:

NFAT PO3 NFAT

Nucleus

IL-1

[Ca2+]

(Step 3 - IL2 stimulation of T cell proliferation):

IL2Receptor

mTOR

T Cell

T Cell

Cell Proliferation

T Cell

T Cell

Cytokine Production

Activation of multiple types of immune cells

Molecular basis for rejection (Steps 1 and 2 - T cell activation and IL2 production):

Calcineurin

NFAT PO3 NFAT

NFAT = Nuclear Factor of Activated T cells

IL-2 mRNA

IL-2 Protein:

Nucleus

IL-1

TT

Tacrolimus(FK506)/FKBP

Cyclosporine/Cyclophilin

T

Prednisone

[Ca2+]

Molecular basis for rejection (Step 3 - IL2 stimulation of T cell proliferation):

IL2Receptor

mTOR

T Cell

T Cell

Cell Proliferation

T Cell

T Cell

Cytokine Production

Activation of multiple types of immune cells

T

Anti-IL-2

TAnti-IL-2receptor

T

Sirolimus(rapamycin)/FKBP T

CyclophosphamideMethotrexateMycophenolate Mofetil

Cyclosporine

*lipophilic cyclic peptide

Mechanism*inhibits transcription of IL-2 gene plus other cytokine

expression (IL-3, gamma interferon)*site of action is a binding protein that inhibits

calcineurin (a phosphatase) involved in signal transduction upon antigen stimulation of T cell receptor

*used for transplant rejection and Autoimmune disorders.

Tacrolimus*macrolide (structure like erythromycin) produced by

streptomyces tsukubaensis.

Mechanism*similiar to cyclosporine except binds to different protein

that inhibits calcineurin (a phosphatase enzyme involved in gene transcription of IL-2, gamma interferon and other cytokines)

*used for transplant rejection and Autoimmune disorders.

*Pimecrolimus*Calcineurin inhibitor like Tacrolimus.*Approved for topical treatment of eczema.

Corticosteroid

Steriod receptors

Corticosteroid

Corticosteroid

*Inhibition of IL-1 and TNF gene expression and synthesis

*Decreased activation of T lymphocytes by decreasing IL-1 release

*Decreased neutrophil functions esp chemotaxis*Decreased antibody production (high doses)*Decreased release of kinins and proinflammatory

eicosanoids (prostaglandins and leukotrienes)*Affects cell-mediated immunity more than humoral

immunity

1. Autoimmune disorders 2. Modulate allergic reactions - asthma3. Organ transplantation – rejection

crisis

Sirolimus (Rapamycin)

*macrolide similiar to tacrolimus isolated from streptomyces hygroscopicus.

Mechanism*binds to immunophilin protein that binds to a key

regulatory kinase required for T cell activation *(new unique mechanism to inhibit T lymphocyte

activation by IL-2)*different site of action than cyclosporine and

tacrolimus

Sirolimus-Inhibits mammalian target of rapamycin (mTOR)

*mTOR is a protein kinase that plays pivotal role in IL-2 receptor responses

*IL-2 binds to its receptor on T cells and leads to mTOR activation

*mTOR initiates cascade of events (including cyclin dependent kinases) that promote T lymphocyte proliferation and differentiation

*Inhibition of mTOR blocks IL-2 dependent cell-cycle progression at G1→S phase transition

Sirolimus

other theoretical actions include:*blockade of B cell Ig synthesis*inhibition of antibody-dependent cellular toxicity*inhibition of lymphocyte activated killer cells*inhibition of natural killer cells*inhibition of immune and nonimmune cell proliferation

(via inhibition of growth factor signaling) (may explain antitumor actions)

Mycophenolate Mofetil*derivative of mycophenolic acid which isolated

from penicillium glaucum.Mechanism

*inhibits inosine monophosphate dehydrogenase involved in de novo synthesis of purines

*selectively suppressess T- and B-cell proliferation

*Also suppresses some macrophage functions (may explain anti-inflammatory actions)

*used for transplanations.

NAD+

NADH

Gln + ATP

Glu+AMP+PPi

guanosine monophosphate (GMP)

GTP

GDP

adenosine monophosphate (AMP)

aspartate + GTP

ATP

ADP

fumarate

GDP + Pi

IMP

Formation of AMP and GMP from IMP

adenylosuccinateXMP

IMP dehydrogenase

Mycophenolate Mofetil

adenylosuccinase

6-mercaptopurine

*Mizoribine inhibit same nucleotide synthesis pathway and very

effective in kidney transplants.

*Brequinar Sodium inhibit de novo pathway of pyrimidine synthesis and

used for cancer & organ transplantation

Antimetabolites (Cytotoxic drugs)

*Immunosuppresion by inhibition of lymphocyte proliferation and cause bone marrow suppression-Azathioprine-Cyclophosphamide-Leflunomide

*Metabolized to 6-mercaptopurines*Inhibit purine synthesis interferes with

nucleic acid metabolism inhibits cellular & humoral responses

*used for Renal allograft, SLE, rheumatoid arthritis, Crohn’s disease.

Azathioprine

*Prodrug of an inhibitor of pyrimidine synthesis

*Inhibits lymphoid cells proliferation.*Approved for treatment of rheumatoid

arthritis.

Leflunomide

*Most potent immunosuppressive drug act as alkylating agent.

*Destroys proliferating lymphoid cells*Used for Autoimmune disorders: SLE

Cyclophosphamide

Other cytotoxic agents*Methotrexate has been used extensively in

rheumatoid arthritis and in the treatment of graftversus- host disease.

*dactinomycin has also been used with some success at the time of impending renal transplant rejection.

*Vincristine appears to be quite useful in idiopathic thrombocytopenic purpura refractory to prednisone.

*isolated from Bacillus laterosporus.*Potent antimonocytic (by ↓ MHC antigen

expression, ↓ antigen processing and presentation and inhibition generation of free radical)

*antilymphocytic effect (by inhibiting antibody production and suppressing cytotoxic cell generation)

*Inhibits T & B lymphocyte response*Renal transplants; pancreas & heart transplants

15-Deoxyspergualin

*Sedative drug*Favors TH2 over TH1 (immunomodulatory

action) with up-regulation of IL-4 and IL-5. *Suppress TNF-α production*Anti-angiogenesis action related for

teratogenicity & anticancer activity.*Indications

-Erythema nodosum leprosum (skin manifestations of SLE)

-Lung transplantation

Thalidomide

FTY720

*prodrug: requires phosphorylation*Sphingosine 1-phosphate receptor (S1P-R)

agonist *Reduces recirculation of lymphocytes from

lymphatic system to the blood*Lymphocyte homing action which reversibly

sequesters host lymphocytes into lymph nodes*Useful in combination therapy but not alone for

autoimmune diseases such as RA.

Drugs that target receptors

Anakinra:*Human IL-1 receptor antagonist*Disease modifier agent for Rheumatoid

arthritis

TNF-α receptors antagonist

Infliximab, etanercept, and adalimumab:*are new biologic agents that bind and block

TNF receptors. results in suppression of downstream inflammatory cytokines such as IL-1 and IL-6 and adhesion molecules involved in leukocyte activation and migration.

*Used for Crohn's disease, rheumatoid arthritis, and psoriatic arthritis.

Antibodies

OKT3 (Muromonab-CD3)*monoclonal antibody to CD3 on T cell*inhibits cytotoxic T killer cell function*opsonizes circulating T lymphocytes and enhances

their removal*used to prevent or reverse acute graft rejection

Antilymphocyte Globulin*polyclonal antibody similiar to OKT3

Antithymocyte Globulin-Rabbit (Thymoglobulin):*Rabbit gamma immune globulin preparation*Composed of antibodies to variety of T cell

markers*Mechanisms

-removal of T cells from circulation-modulation of T cell activation, homing and

cytotoxicity-decreases cytokine induced reactions

IL-2 Receptor Antibodies

-Basiliximab and Daclizumab: *monoclonal antibodies against human IL-2 receptor

alpha subunit of activated T to block T cell*Blocks activation and inhibits clonal expansion of T

cells*Used to induce immunosuppression and to prolong

organ transplants in combination with immunosuppressants

Alefacept

*Recombinant DNA-derived humanized monoclonal antibody

*It inhibits activation of T cells by binding to cell surface CD2 and inhibiting the normal CD2/LFA-3 interaction

*approved for the treatment of plaque psoriasis

Efalizumab

*is a humanized IgG1 mAb targeting the LFA-1 (lymphocyte function associated antigen).

*Efalizumab binds to LFA-1 and prevents the LFA-1-ICAM (intercellular adhesion molecule) interaction to block T-cell adhesion, trafficking, and activation.

*used for graft rejection and psoriasis.

Alemtuzumab*New Immunosuppressant*Recombinant DNA-derived humanized

monoclonal antibody *Binds to CD52. a nonmodulating antigen present

on surface of all T and B cells *Some bone marrow cells express CD52 including

some CD34+ cells*Produces profound T cell depletion *Used for for selected leukemias and lymphomas

also for stem cell transplant procedures

Other Antibody Preparations

Rh(D) Immune Globulin*for Rh (neg.) mother after delivery of Rh(pos.) baby.

Abciximab*for surface receptor on activated platelets to prevent

restenosis after coronary angioplasty

Rituximab*for CD20 on pre-B and mature B cells to treat non-

hodgkins lymphoma

Palivizumab*monoclonal antibody that binds to the fusion

protein of respiratory syncytial virus, preventing infection in susceptible cells in the airways.

Trastuzumab*monoclonal antibody that binds to the extracellular

domain of the human epidermal growth factor receptor HER-2/neu. Used for treatment of metastatic breast CA

Immunostimulants

*These drugs increase the immune response for patients therefore used in:

1. Infection treatment.2. Immunodeficiency3. cancer

Immunostimulatory Cytokines

Interleukins*IL-2 (enhance antitumor actions of cytotoxic T cells and

NK cells) and therefore use for treatment of cancer such as renal carcinoma and malignant melanoma.

Colony Stimulating Factors*G-CSF (neutropenia) and GM-CSF (bone marrow transplant patients)*GM-CSF can itself stimulate an antitumor immune response, resulting in tumor regression in melanoma and prostate cancer

INF uses*Interferon Alpha (prod. by leukocytes)

-(antiviral, antiproliferative)-malignant melanoma, renal cell carcinoma, hairy cell

leukemia, Kaposi’s sarcoma

*Interferon Beta (prod. by fibroblasts)-(antiviral, antiproliferative)-relapsing type Multiple Sclerosis.

*Interferon Gamma (prod. by lymphocytes)-(stimulates NK cells and macrophages)-chronic granulomatous disease

*antiparasitic agent*Later studies suggested that it increases the magnitude of delayed hypersensitivity or T cell-mediated immunity in humans.*potentiate action of fluorouracil in adjuvant

therapy of colorectal cancer.*Also may used for hodgkin’s lymphoma and

RA

Levamisole

Bacillus Calmette-Guerin

*Suspension of attenuated Mycobacterium bovis

*Stimulates cell-mediated immunity (immune adjuvant)

*Used as a topical agent for superficial cancers of the urinary bladder with an 80% response rate.

* A variety of microbial products, including whole organisms and extracts, have been used in Japan as immunomodulators in standard cancer treatments. These have included picibanil (OK432), lentinan, and pachymaran. Clinical trials, usually historically controlled, showed a prolongation of remission and survival. These agents stimulate macrophages to release various cytokines, including IL-1, colony-stimulating factors, and TNF-α.

Inosiplex, Diethylcarbamate (DTC), Azimexon, ciamexon, and imexon:

*has immunomodulating activities By increasing natural killer cell cytotoxicity as well as T cell and monocyte functional activities. *These drugs found to reduce infections and slow progression in some patients withadvanced HIV infection.

Other immunostimulants

Hematopoietic AgentsErythropoietin alpha

*Stimulates division and differention of erythroid progenitor cells

*Used for anemia due to renal failure or cancer chemotherapy

* Short duration of action.

Darbopoetin alpha*Recombinant long-acting erythropoetin.

Thymic Hormones*Thymosin consists of a group of protein

hormones synthesized by the epithelioid component of the thymus.

*Smaller peptides and recombinant molecules such as thymosin- 1, thymic humoral factor, and thymopentin, may have similar activity

*Used for treatment of DiGeorge Syndrome of T cell deficiency

Cancer immunotherapy

1. Active nonspecific immune stimulation eg, BCG2. Active specific immune stimulation eg,

melanoma cell vaccine3. Immunomodulators eg, Levamisole4. Cytotoxic cytokines eg, INF-α5. Immunostimulatory cytokines eg, IL-26. Adaptive cellular immunotherapy eg, antigen

pulsed dendritic cells7. Monoclonal antibodies eg, anti-HER-2.

Immunotherapy and vaccination

1. Live attenuated2. Whole killed3. Subunit (purified /partially purified protein

from organism)4. Recombinant5. Polysaccharide 6. Toxoid 7. Future: vectored, peptide and DNA.

Tolerogens

TOLEROGENS-Two signals required for T cell activation

*Signal 1 via T cell receptor*Signal 2 via costimulatory receptor-ligand pair

- While Immunosuppressants has concomitant risks of opportunistic infections and secondary tumors therefore tolerogens may solve this problem.

Normal T Cell Response

T Cell Anery (No Response)

Inhibitory and Stimulatory APC Molecules

Costimulatory Blockade

-Experimental approaches to inhibit costimulation include:

1- Anti-CD80 and anti-CD86 mAbs. approved for renal transplantation.

2- Anti-CD28 antibody which may used for rheumatoid arthritis

3- Anti-CD154 antibody block CD 40L to interact with CD 40 in APC used in clinical trials in renal transplantation and autoimmune diseases.

Thanks