IJSTD 1998;19:1-21

IMMUNOSUPPRESSION - BLISS AND CURSE: a tale of two poisons

NK Mathur and Puneet Bhargava

Jaipur

In the present era, monitored immunosuppression by Cyclosporin-A(CsA) is a bliss for organ transplant patients, while much similar, but unabated, immunosuppression by Human Immunodeficiency Virus (HIV) is no less than a curse on mankind. This review is a collection of similarities in the actions of these agents on human systems. As a back drop of these common toxicities, we have developed a drug based on principles of Homoeopathy.

HISTORICAL BACKGROUND

Cyclosporin A (Cs-A) is a neutral, homodetic, hydrophobic, cyclic 11- peptide isolated from Tolypocladium inflatum Gams fungal species.¹ It is widely used following organ transplant due to its unique and remarkably effective immunosuppressive properties. The credit of its discovery goes to Sandoz laboratory, Switzerland, where in early 1970, they took up the study of metabolites from various soil fungi to study their anti-bacterial and anti-mitotic properties.¹ Tolypocladium inflatum Gams was one of them. Ruegger extracted a mixture of cyclosporins and named it compound 24-556.¹ In 1971, Borel and his team started working on the immunosuppressive properties of 24-556 and by early 1973 demonstrated that 24-556 suppresses both antibody production and cell mediated immunity. Later, Reugger separated CsA from compound 24-556.² Soon, Borel et al (1976) described the antilymphocytic properties of CsA. Another milestone was the year 1978 when first clinical trials of CsA were conducted in patients of kidney transplantation.¹ While CsA was under development, HIV, the causative agent of AIDS was brewing some where in central Africa. The oldest evidence of its infection comes from a study by Saxinger et al, where they examined sera obtained from a 1972 study of Ugandan children and found that 65% of apparently healthy children had sera positive for HIV.³ The year 1981 signified the arrival of HIV infection in USA, when a number of reports appeared describing unexpected deaths among young homosexual men caused by Kaposi’s sarcoma, unexplained opportunistic infections, or both.^4,5 It was not until 1983 that HIV was actually isolated.^6,7 Similarly 1983 was an important year for CsA also as it was in this year that CsA was first approved and registered for transplant patients¹ in USA, Switzerland and some other major countries. The first enzyme immunoassay to detect antibodies to HIV was licensed in 1985, ⁸ while the monoclonal antibodies against CsA were developed in 1987. ⁹

STRUCTURE

CsA and HIV-1 gag share structural similarities, as both CsA and gag capsid protein structure consists of eight stranded b - barrels which have binding sites for intracellular proteins; cyclophilins, the peptidyl-prolyl-cis-trans isomerases, which assist in the intracellular folding of proteins.¹⁰ CsA-cyclophilin-A complex binds to calcineurin contributing to immunosuppression produced by CsA. Gag-cyclophilin combination helps in viral replication and although this complex does not bind to calcineurin, it may contribute to HIV induced immunosuppression by inhibiting the binding of the cyclophilins to a possible physiological ligand.¹⁰

T-Cell : CD4+ T lymphocytes are the key regulators in the immunosuppression produced by HIV and Cyclosporin.^11-14 Both HIV and CsA interfere with intracellular pathways in T-cell activation^15-20 and depletion of these cells.

Intracellular signaling pathways in T-cell activation (fig1):

T-cell activation process begins with the association of peptide-MHC complex with TCR-CD4 molecule. This association activates intracellular phosphotyrosine kinases (PTKs). Three different PTKs have been implicated in early phosphorylation events (lck associated with cytoplasmic tail of CD4 and fyn and zap kinase with z -chain of TCR complex). These PTKs phosphorylate tyrosine moieties of the enzyme phosphatidylinositol phospholipase C-g 1(PI-PLC-g 1) and activate it. PI-PLC-g 1 catalyses hydrolysis of plasma membrane phospholipid called phosphatidylinositol 4,5 biphosphate to Inositol 1,4,5 triphosphate (IP₃) and diacylglycerol (DAG). IP₃ stimulates release of membrane sequestered intracellular calcium, which then forms complex with a calcium dependent regulatory protein called calmodulin. Calcium - calmodulin complex activates a phosphatase Calcineurin. Calcineurin dephosphorylates cytoplasmic component of NFAT (nuclear factor of activated T-Cells) called NFATc and permits it to enter the nucleus. Diacylglycerol activates protein kinase C (a serine/threonine protein phospho kinase). This activation leads to fos/jun synthesis and AP-1 (another nuclear factor) generation. Inside the nucleus NFAT_C, combines with newly synthesised AP-1 proteins and this complex binds to NFAT binding sequences of the IL-2 promoter, leading to increased IL-2 transcription and cellular activation.^21-23 PKC also phosphorylates Ik B, an inhibitor of NFk B (Nuclear factor of immunoglobulin k light chains in B cells) to activate NFk B, which is then translocated to the nucleus and binds to IL-2 promoter site to increase IL-2 transcription.^21-23 IL-2 promoter contains additional binding site for another factor NFIL-2A, composed of 2 proteins OCT1 and OAP. NFIL-2A activation occurs through TCR but the final pathway is not clear.^21-23 Cyclosporin inhibits this cycle at multiple steps. It binds to a family of intracellular proteins called cyclophilins (CyPs).¹⁵ Cyclophilins have the ability to catalyse cis-trans intra conversion of peptidyl-prolyl bonds and promote protein folding in cells.^24,25 Cyclosporin-cyclophilin combination binds to calcineurin and inhibits its activity.^16,17 In addition CsA binds to calmodulin and inhibits its ability to activate calcineurin.¹⁸ Further CsA also interferes with the translocation of NFAT_C in the nucleus ^26,27 and its binding to the IL-2 promoter.²⁸ Translocation of NFk B to the nucleus and its binding to IL-2 promoter is also CsA sensitive.^29,30 At the same time, induction of NFIL-2A DNA binding activity is also inhibitable by CsA.¹⁷ Although the knowledge about how HIV affects this cycle is incomplete, it appears that binding of gp 120 to CD4 disrupts the earliest events in signal transduction. This disruption may result from activation of lck through CD4 before TCR signaling, which may result in a negative signal, ³¹ sequestration of lck, ³² activation of a negative regulatory kinase such as csk or inactivation of CD45, a key regulator of early T cell activation events.¹⁹ Binding of HIV gag to cyclophilins may inhibit cellular activation and induce immunosuppression in a manner similar to CsA.³³Gupta S (1993) has hypothesised after studying HIV infected mononuclear cells, that the defect may lie downstream of PKC.²⁰ Glutathione deficiency may also contribute to defective T-cell signal transduction by altering cellular redox potentials in HIV-AIDS.¹⁹

CD₄⁺ cell functions: Dysregulation of CD₄+ helper cell functions occurs long before depletion of these cells^34-35 in HIV-AIDS . Acute primary phase in HIV-1 infection is characterised by low serum IL-2 concentration.³⁶ With progression and HIV seroconversion, a sequential loss of TH functions is seen; earliest being response to recall antigens such as influenza A virus, tetanus toxoid and HIV synthetic peptides, followed by the allo- major histocompatibility complex and finally by phytohemagglutinin (PHA).³⁷ Similarly, IL-2 and lymphokine production are the most sensitive of all lymphocyte functions to CsA (50% inhibitory concentration 10-20 ng/ml), followed by cellular proliferation (20-50 ng/ml), response to CON A (200-500 ng/ml) and PHA (500-1000 ng/ml).^38-39

CD₄+ cell count and mechanisms of depletion: HIV-AIDS shows a rapid decline in CD₄ cell counts with disease progression.^40-41 Although cyclosporin at the normal maintenance dose (100-200 ng/ml) is not lymphotoxic,^38-39 it may share a number of mechanisms of cell death with HIV at higher concentration. Apoptosis is one of the main mechanisms of cell death in HIV infection. HIV tat upregulates CD95 ligand expession in CD₄+ cells and sensitizes them to TCR and CD4 induced apoptosis by soluble gp 120.⁴² Similarly, Huss et al (1995) observed that CsA induces apoptosis in canine CD₄+ lymphocytes in a time and dose dependent fashion over a range of 6 to 10 m g/ 100 m l.⁴³ Encoded retroviral products and microbes such as S. aureus can act as superantigens (a group of microbial antigens which can bind to specific Vb determinants on T cells resulting in massive stimulation, followed by deletion or anergy of these cells) and contribute to HIV induced immunosuppression.^44-47 Similarly CsA can promote superantigen mediated cell death in CD₄+ lymphocytes.⁴⁸ Experimental and clinical evidence suggests that CD8+ suppressor cells play a role in AIDS progression by causing CD4⁺ helper cell depletion.⁴⁹ Likewise, generation of suppressor cells and reversal of TH:TS ratio is seen after CsA therapy.⁵⁰ Other mechanisms of depletion of CD4⁺ lymphocytes in HIV infection are direct cytopathic effect by HIV, formation of multinucleated giant cells or syncytia, uninfected CD4⁺ cell destruction by antibody dependent cellular cytotoxicity, NK cells and HIV-specific cytolytic T lymphocytes and autoimmune mechanisms.^51-52

Macrophage/monocyte: Cells of monocyte /macrophage lineage are among the primary cells infected by HIV⁵³and form its major reservoir of HIV.^54-55 Although,mild functional abnormalities such as defects in chemotaxis, secretion of IL-l, F_C receptor functions, oxidative burst responses, C3 receptor mediated clearance, certain cytotoxic functions and most importantly, defective antigen presentation and induction of T-cell responses are seen in HIV-AIDS,^56-57 most studies have shown that changes in blood monocyte number, phenotype and functions are minimal even in late stage disease.^55,58 Cyclosporin-A directly interferes with antigen presenting function of macrophages^59-61,while other functions such as phagocytic (in vitro or in vivo) or migratory activity and LPS induced IL-1 production are insensitive to drug concentrations that markedly affects T cell functions.⁶²

Dendritic cells(DC) including Langerhans cells: HIV infects Langerhans cells and peripheral blood dendritic cells both in vitro and in vivo. ^63-66 Low dose viral exposure generates protective cytotoxic cell response directed against a variety of epitopes of HIV-1.⁶⁷ At higher viral load and longer time of exposure, antigen presenting functions of DC are compromised;⁶⁸ reduced classII and ATPase levels being the first indicator of altered Langerhans cell functions;⁶⁹ and DCs lose their capacity to stimulate antiviral responses in T cells.⁷⁰ Very high viral load in mature DCs results in syncytium formation and death of DCs and of any clustered T cells.⁷¹ Similarly in vitro studies have shown that CsA inhibits the accessory and antigen- presenting functions of Langerhans cells, directly in a dose dependent manner.⁷²

B-cells: Cyclosporin can inhibit directly the activation of B-lymphocytes to a variety of stimuli by interfering with Ca++ dependent signals.⁶² Similarly functional B-cell defects are also seen in HIV infection.⁷³ Lun et al (1991) have shown that along with inhibiting B cell activation, CsA may also decrease or increase the differentiation and Ig production by B cells, depending on the antigen used.⁷⁴ Similarly HIV is also a B-cell mitogen and induces polyclonal B-cell activation and Ig production by the cells.⁷⁵

Natural Killer cells: Accumulated evidence indicates that NK cell responses are normal or elevated in early phases of AIDS,^76-77 however progressive decline in function are noted with increasing duration of HIV infection.⁷⁸ Mechanisms may include reduction in circulating levels of IL-2 required for proliferation of NK cells, or inhibition of cellular functions by HIV-1 viral peptides.⁷⁹ NK cell activity is only mildly impaired under normal CsA therapeutic dose.⁸⁰ However, a dose dependent inhibition of NK cell activity is noted when NK cells are exposed in vitro to CsA.⁸¹

Mast cells: Animal studies have shown that CsA directly leads to depletion of mast cells and reduces secretion of mast cell specific proteases.⁸² Triggiani et al (1989) showed that CsA inhibits release of histamine and prostaglandin D₂ from human lung mast cells.⁸³ Similarly, decreased skin reactivity to codeine in patients with AIDS is due to decrease of local mast cell density or releasibility.⁸⁴

Glutathione deficiency: Glutathione is an important antioxidant which protects the body from free radical injury. HIV infection produces systemic glutathione deficiency ⁸⁵ which correlates strongly with low CD₄ count, impaired IL-2 production and proliferation of peripheral blood mononuclear cells, ⁸⁶ and increased incidence of adverse reactions to Co-trimoxazole due to failure to detoxify its hydroxylamine derivatives.⁸⁷ CsA also produces glutathione deficiency and the resultant oxidative stress contributes to its hepatotoxicity and nephrotoxicity.^88-89

Selenium: Selenium is an important component of glutathione peroxidase, which is depleted in HIV positive and CsA treated individuals.^90-92 Selenium levels are low in patients with AIDS and this deficiency may be associated with myopathy, cardiomyopathy, immune dysfunctions, decreased T-cell counts and impaired phagocytic functions⁹¹seen in these patients. In CsA treated patients, selenium supplementation seems to prevent the vascular toxicity.⁹²

Magnesium: Cyclosporin therapy has been associated with renal magnesium wasting and hypomagnesemia. ⁹³ Belief is that this drug induced hypomagnesemia may lead to hypertension,⁹⁴ contribute to neurotoxicity⁹⁵ and may exacerbate cyclosporin induced nephrotoxicity.^96-97 Similarly low magnesium levels are found in HIV-AIDS patients.^98-101 There is direct co-relation between hypomagnesemia and absolute CD₄ counts.^98,101 Further, low magnesium level may lead to lethargy, impaired mentation⁹⁹ and convulsive status epilepticus¹⁰⁰ in these patients.

Zinc: Low plasma Zinc levels are found in both HIV infected¹⁰² and CsA treated individuals,¹⁰³ although high levels have also been reported after CsA therapy.¹⁰⁴

Lipid Metabolism: Immunosuppressive therapy with CsA has been associated with significant increase in LDL cholesterol.¹⁰⁵ On long term immunosuppresion, this hyper-cholesterolemia may be a potential risk for atherosclerosis. Similarly HIV-AIDS patients have been shown to have a large number of lipid metabolism abnormalities including abnormally elevated triglyceride levels,¹⁰⁶ raised fatty acid turnover,¹⁰⁷ raised fat oxidation rates unrelated to counter-regulatory or thyroid hormone increase¹⁰⁸ and relative loss of lean body mass compared with fat.¹⁰⁹

Thymus: Thymus is an important organ for T cell maturation and differentiation. Thymocytes develop into T cells in the thymic microenvironment consisting of epithelial cells, macrophages and interdigitating cells (IDCs) which produce different cytokines involved in thymocyte maturation.^110-111 Both HIV and CsA are known to affect thymus. ^112-113 HIV infection produces rapid involution of thymus.¹¹⁴ Similarly CsA causes a marked reduction in the size, weight and consistency of the organ.¹¹⁵ Microscopy shows that in HIV infection, there is fatty replacement of thymus with loss of corticomedullary junction, paucity of Hassall’s corpuscles and depletion of lymphocytes and keratin positive epithelial cells.¹¹⁴ Studies in mice have shown that CsA also results in loss of medulla, loss of keratin positive epithelial cells, Hassall’s corpuscles and lymphocytes.¹¹⁶ Study of the cell types affected shows that both HIV and CsA cause depletion and prevent maturation of immature CD4+ CD8+ (DP) cells into CD4+ CD8- and CD8+ CD4- (SP) cells.^112,113,117 This effect occurs by similar mechanism like accleration of apoptosis by both HIV and CsA.^112,116,117 Further CsA disrupts thymic micro- environment.¹¹⁶ Similarly HIV infection of thymic macrophages, dendritic cells and epithelial cells may compromise their functions in regulating thymopoiesis.^118,119 This compromise on the functions of thymic microenvironment may further contribute to the depletion of CD4+ CD8+ (DP) cells ^112,113 by both HIV and CsA.

Central Nervous System function: AIDS dementia complex or HIV encephalopathy is probably the most common CNS complication of HIV infection.¹²⁰ Patients present with a decline in cognitive ability from a previous level, along with motor and behavioural dysfunctions.⁵⁶ Mechanisms include gp120 mediated neuronal toxicity, myelin damage produced by viruses other than HIV (measles, herpes simplex and JC virus), destruction of white matter by host immune responses, and possible involvement of quinolinic acid and TNF-a .^121-125 Similarly cyclosporin therapy is associated with both reversible and irreversible dementia. This pathology arises secondarily to cyclosporin induced hypertension or vascular injury.^126-130 Both partial and generalised seizures complicate HIV-AIDS, probably as a consequence of HIV encephalopathy, opportunistic infections and neoplasms.^120,131,132 Similary, seizures are a common side effect of CsA therapy.^133-136 Although multiple factors are involved, they probably arise as a result of cyclosporin induced lower seizure threshold.¹³⁵ Peripheral neuropathies including distal sensory polyneuropathy, mononeuritis multiplex, isolated mononeuropathy, polyradiculopathy and acute inflammatory demyelinating neuropathy (Guillain-Barre syndrome) arise in HIV infection.^137-140 Probable mechanisms are related to HIV mediated axonal degeneration, autoimmunity, associated infections (CMV and Mycobacterium avium intracellulare) and Vit B₁₂ deficiency.^137-142 Similarly, CsA therapy is associated with a demyelinating polyneuropathy.^143-145 Cyclosporin also enhances virally induced T-cell-mediated demyelination.¹⁴⁵ There are also isolated reports of Guillain-Barre syndrome arising following immunosuppression involving cyclosporin.^146-147 Wasserstein et al (1996) observed parkinsonism in two patients receiving cyclosporin.¹⁴⁸ One patient improved with carbidopa-levodopa therapy and other with reduction of cyclosporin dosage.¹⁴⁸ Similarly, parkinsonian symptoms with markedly reduced dopamine concentration in caudate nucleus are seen in HIV-AIDS.^149-150

Neuro-Psychiatric Manifestations: Reversible visual hallucinations may occur in a dose dependent manner following cyclosporin therapy.^151-152 Similarly, hallucinations may be a part of psychosis associated with HIV infection.^153-154

Renal abnormalities: Both HIV infection and CsA produce renal abnormalities.^155-159 About 10% of HIV-1 infected patients develop a chronic renal disease characterised by tubular changes (microcystic tubular dilation and regeneration), interstitial inflammatory infiltrate and more commonly, focal segmental and global glomerulosclerosis (FSGS). This entity is termed as HIV associated nephropathy.^155-156 CsA, similarly produces renal side effects, but in a dose dependent manner,¹⁵⁷ including tubular changes (isometric vacuoles, inclusion bodies, microcalcifications), striped interstitial fibrosis and more seriously, focal and segmental glomerulosclerosis.^157-159 Recent evidence shows that Transforming growth factor-b (TGF-b ) may be involved in HIV associated FSGS.¹⁶⁰ HIV-1 tat has been shown to increase the release of TGF-b 1 from bone marrow macrophages.¹⁶¹ Similarly, cyclosporin has been shown to enhance the expression of TGF-b , both in vivo and in vitro¹⁶² and TGF-b has been implicated in CsA augmented fibrogenesis,¹⁵⁸ although angiotensin II may also be involved in this process.¹⁶³

Cardiac abnormalities: Although there has been controversy whether HIV directly affects heart, cardiac lesions have been found in both HIV infection and after cyclosporin therapy.^164-169 CsA in a dose dependent manner produces perimyocytic fibrosis¹⁶⁴ and severe myocardial calcification.^165-166 Similarly, autopsy studies have shown that cardiomyopathic changes like myocyte necrosis, myocyte hypertrophy and diffuse myocardial fibrosis are common in AIDS.^167-168 Calcification in the media of most major vessels is typical of HIV arteriopathy.¹⁶⁹

Hypertension: Systemic hypertension is a frequent side effect of CsA therapy.^170-172 Mechanisms include activation of endothelin system,¹⁷³ sympathetic nervous system¹⁷⁴ and renin angiotensin system.¹⁷⁵ Although systemic hypertension is not seen, plexiform variant of pulmonary arterial hypertension related to chronic HIV infection does occurs in HIV- AIDS.¹⁷⁶

Testicular functions: Both CsA and HIV affect testicular functions.^177-184 Cyclosporin induces a dose dependent decrease in serum and intratesticular testosterone levels and produces impairment of testicular spermatogenesis, steroidogenesis, epididymal sperm maturation and fertility in rats.^177-178 These effects are reversible on discontinuing CsA therapy.¹⁷⁹ Mechanisms include direct inhibition by CsA of testosterone biosynthesis at multiple sites, interference with signal transduction pathways¹⁸⁰and suppression of hypothalamo-pituitary axis.¹⁷⁷ Similarly, hypogonadism is seen in approximately 50% HIV infected individuals.⁵⁶ Laudat et al (1995) showed that hypogonadism occurs as the CD4 lymphocytes decrease and dehydroepiandrosterone (DHEA), androstenedione, dihydrotestosterone (DHT)and non-SHBG testosterone levels correlate with CD4 counts.¹⁸¹ Probable factors leading to hypogonadism include peripheral inhibition of testosterone biosynthesis by HIV, opportunistic infections, chronic debilitating illnesses and suppression of hypothalamo- pituitary axis by cytokines.^182-184

Hepatobiliary system : Cholestasis, manifested by increased levels in serum bilirubin, alkaline phosphatase and gamma-glutamyl transferase, is the most frequent manifestation of CsA hepatotoxicity.^185-186 It is dose dependent and is often associated with a variable component of cholangitis and pericholangitis. It is probably mediated through non- competitive binding of CsA to the bile acid transporter at the cell membrane.^187-189 Similarly, cholestasis as a component of biliary disease occurs in patients with CD4 counts less than 100 per mm³ in AIDS.¹⁹⁰ The underlying causes may be related to papillary stenosis, cholecystitis, sclerosing cholangitis and intrahepatic abnormalities.¹⁹¹

Pancreatic functions: Cyclosporin, when administered to rats in therapeutic doses, leads to glucose intolerance, hyperglycemia, hypoinsulinemia and marked decrease in pancreatic insulin content.^192-195 Accumulated evidence indicates that CsA has a direct toxic effect on islet b cell functions, leading to impaired insulin synthesis and secretion.^196-199 Ultrastructurally, varying degrees of vacuolization and dilation of endoplasmic reticulum and golgi apparatus can be observed in b cells accompanied by reduction in the number of secretory granules.^200-201 Similarly, pancreatitis leading to abnormalities of glucose metabolism are seen in HIV infection.^56,202-204 Probable mechanisms of pancreatic dysfunction include drug toxicity by pentamidine and dideoxynucleosides, opportunistic infection (CMV, MAC, candida, cryptosporidia ) and neoplasms.^202-204

Gingival involvement: Gingival hyperplasia occurs frequently after CsA therapy.^205-206 Similarly human immunodeficiency virus - associated gingivitis (HIV-G) is a frequent finding among oral manifestations of HIV infection.^207-209

Muscular System: HIV associated myopathy, now a well defined condition, ranges from an asymptomatic elevation in creatine kinase to a subacute syndrome characterised by proximal muscle weakness and myalgias.^56,210-212 It may occur at any point of HIV-1 disease.²¹⁰ Cyclosporin therapy, too, is associated with a dose dependent toxic myopathy characterised by myalgias, muscle weakness or rhabdomyolysis.^213-215

Pulmonary function: Recent reports have documented the occurrence of adult respiratory distress syndrome (ARDS) after cyclosporin therapy.^216-217 It is believed that high concentration of cyclosporin in the pulmonary vasculature causes a localized ‘capillary leak’²¹⁶ or it may be an idiosyncratic reaction to cyclosporin.²¹⁷ ARDS also occurs in HIV-AIDS, probably as a manifestation of diffuse lung injury produced by toxoplasmosis,²¹⁸ pneumocystis carinii pneumonia,²¹⁹ cryptococcosis,²²⁰ pulmonary tuberculosis²²¹ and varicella infection.²²²

Hemolytic Uremic Syndrome and Thrombotic thrombocytopenic purpura: Cyclosporin therapy is related to the development of a syndrome resembling thrombotic thrombocytopenic purpura (TTP) or hemolytic uremic syndrome (HUS).^223-227 Probable mechanisms include defective synthesis and release of prostacyclin from endothelial cells,²²⁸ and excessive platelet aggregation due to increased utilization of high molecular weight multimers of factor VIII, whose levels are raised after vascular injury induced by cyclosporin.²²⁹ Complications, HUS and TTP, are also seen in patients of HIV infection. These lesions probably arise secondary to HIV infection induced endothelial injury.^230-235

Hypertrichosis: Hypertrichosis of eyelashes has been recently described as a cutaneous marker for AIDS .²³⁶ Like wise, trichomegaly^237-239 and generalised hypertrichosis is one of the common side effects of CsA , seen not only in normal, but also in pathological conditions of hair growth such as alopecia areata and in some patients of male pattern alopecia.²⁴⁰ Hair growth by both CsA and HIV is probably due to direct stimulant effect on hair follicle keratinocytes ^241-243 or secondary to immune dysregulation.²⁴²

INFECTION: Basic defects in both HIV infection and CsA treated patients include T cell functions, macrophage and NK cell activity. Therefore, it is expected that intracellular pathogens should be common in both HIV infected and CsA treated individuals. Both the primary and reactivating CMV diseases are common in CsA treated patients.^244-245 CMV retinitis occurs in HIV infected individuals and is an AIDS defining illness.⁵⁶ EBV induced lymphoproliferative lesions occur both in AIDS and after CsA treatment.^246-247 Dummer et al have observed high incidence of herpes simplex virus infection in CsA treated heart transplant recepients.²⁴⁸ Animal studies have shown that infection with viruses such as Sindbis virus, vaccinia²⁴⁹ and herpes virus²⁵⁰ are worsened after CsA therapy. CsA enhanced the release of vesicular stomatitis virus and polio in murine cell line in one study.²⁵¹ Similarly, other viral infections such as herpes zoster and molluscum contagiosum occur floridly in HIV infection.⁵⁶

CsA has also been shown to induce a number of bacterial infections including pneumocystis carinii in rats,²⁵² while infections such as florid mycobacterium tuberculosis do not occur as frequently in CsA treated patients as in AIDS. This could be related to the degree of immunosuppression which is not as great with therapeutic dose of CsA as seen in HIV infection. Takashima T. et al showed in mice experiment that dose dependent inhibition of resistance to the BCG strain of Mycobacterium bovis is seen during cyclosporin treatment.²⁵³ Among the various fungi, CsA has shown to significantly increase virulence of cryptococcus in rabbit model.²⁵⁴ Extrapulmonary cryptococcosis is common in AIDS⁵⁶ but the matter is complicated as CsA itself has an anti- fungal activity.²⁵⁵

AUTOIMMUNITY: Although CsA has been used clinically to control allograft rejection, GVHD and some autoimmune diseases,²⁵⁶ it paradoxically induces syngeneic GVHD and other autoimmune diseases in some cases.²⁵⁷ The probable mechanisms include blocking of intrathymic clonal deletion of autoreactive T-Cells,²⁵⁸ deletion of peripheral T-Cells and inhibition of anergy induction⁴⁸ and inhibition of "veto cell" mediated clonal deletion of post thymic precursor cytotoxic T lymphocytes.²⁵⁹ Similarly, autoimmune phenomena with similarity to SLE²⁶⁰ and GVHD²⁶¹ occur in HIV-AIDS. Antibodies to DNA, erythrocytes, lymphocytes, neutrophils, platelets and immunoglobins are common.^262-264 Probable mechanisms of HIV induced autoimmunity include viral induction of polyclonal B cell activation, coating of infected cells with viral proteins and making them targets for cytotoxic T cells, increased MHC-II expression of immune and epithelial cells and cross reactions between some viral antigens and MHC-II molecules.²⁶⁵

Kaposi’s Sarcoma is the most common neoplasm in patients with AIDS²⁶⁷; similarly, KS is very common following CsA treatment and its incidence is 2-4 times higher than in patients receiving CIT.²⁶⁸ Moreover, in CsA treated patients, the onset of the disease is much earlier than in CIT.²⁶⁸ Epidemiological evidence strongly suggests that both AIDS associated and non AIDS associated forms of KS have infectious causes.²⁶⁹ Earlier, CMV was the only pathogen which was commonly found to be associated with KS .²⁷⁰ Chang et al (1994) recently identified DNA sequences of a new herpes virus, provisionally termed KS associated herpes virus (KSHV) in vast majority of AIDS associated KS lesions.²⁷¹ Similar sequences have now been identified in post transplantation KS.²⁷² HIV tat may also act as a cofactor in induction of KS. HIV tat has shown growth promoting effects on KS spindle cell cultures in vitro²⁷³ and tat receptors are present in HIV-1 associated KS.²⁷⁴ CsA associated KS regresses following withdrawal of CsA treatment,^275-276 suggesting, that CsA probably has a direct promoting action on KS cells.²⁷⁷ It has also been seen recently that HIV-tat down regulates the expression of P⁵³ oncosuppressor gene product resulting in AIDS related malignancies.²⁷⁸ Similar downregulation of P⁵³ has been seen in transplanted, CsA treated, KS patients. ²⁷⁹

Lymphomas: B-cell lymphomas are common in AIDS²⁴⁶ and post transplant CsA therapy.²⁶⁸ Gastrointestinal tract is the most common extranodal site for lymphomas in HIV infected and post transplant CsA treated patients.^247,268 EBV has been implicated in both CsA and HIV associated lymphomas.^247-248 It is believed that the virus gets activated after T-cell inhibition, causing B-cell proliferation which may lead to the emergence of a neoplastic population of B-cells.²⁴⁷Another mechanism is that viral tat can also activate B-cells²⁸⁰ leading to their hyperproliferation. Similar direct growth promoting effect on lymphomas has been seen with CsA.²⁷⁵ Other malignancies common in AIDS including cervical carcinoma and anal carcinoma are also common with CsA therapy.^268,281

It is evident from the above review that both CsA and HIV share common pathophysiological pathways in achieving the common goal of immunosuppression. CsA achieves immunosuppression by specifically targeting IL-2 genome, while HIV targets cell genome and hijacks its functional capabilities. HIV and CsA also have structural and functional similarities; gag and CsA have b -barrel structure that binds to similar intracellular targets (cyclophilins), tat and CsA augument TGF-b secretion and fibrosis, downregulate P⁵³ gene and promote tumour growth and, tat, gp-120 and CsA induce apoptosis in CD4 cell lines. Interestingly, other pathological effects like organ system abnormalities, cacinogenesis, infections, autoimmunity, angiogenesis and destruction of immature thymocytes also show great simulation. HIV,being a progressive infection, produces the above pathological changes in a quantum and time dependent manner, analogus to the dose dependency seen with CsA, which has been further supported by toxicological studies done in animals. However, regulated therapeutic use of CsA causes minimal and tolerable side effects.

Homoeopathic philosophy, Similia similibus curenter, suggests that when a toxic substance is given in dilutions ( potentised form ), it brings cure for the toxic effects it produces when given in crude form. Keeping this in mind, we prepared various dilutions of Cyclosporin.

PRELIMINARY STUDIES WITH POTENTISED CYCLOSPORIN (Homoeopathic form)

1. Three potencies of the drug, 30,200 and 1000 and a control, were tested in normal Albino mice (ten animals in each group) to see their effect on various organs. The drugs were given orally, once a day, for three months. No change was observed in the behavior, weight and food intake. Autopsy did not reveal any gross abnormality in liver, kidney, thymus, spleen and lymph nodes (routine histology).

2. Lymphocytes from mice sensitised with Salmonella antigens (live or inactivated), when incubated with this drug showed increase in IP3, intracellular Ca2+, increased PKC, increased production of IL2 & gamma IFN (Thl) and increased production of IL4 (Th2) and increased TNF- a . These observations indicate that even Homoeopathic drugs can be tested in vitro.

3. When lymphocytes from two HIV-1 infected patients (CD4 count 400 to 500) were incubated with this drug, the following observations were made:

  To us these results indicate that this drug has potential to stimulate lymphocytes. What is to be seen further is, how in the presence of this drug, lymphocytes react to HIV, whether this drug reduces infectivity, viral load or prevents apoptosis. The present antiviral drugs are handicapped as: (1) they develop resistance, (2) have access to a few viral reservoirs and (3) are not free from side effects. This drug acts on the host and it may be possible that training of the host to fight virus is a better alternative than antiviral drugs(s) alone.

Address for correspondence: Dr NK Mathur, C–24 Peeyush Path, Bapu Nagar, Jaipur - 302015, INDIA

E- mail nkmathur@nkmathur.com

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