Statins Used As Immunosuppressants

There are a new batch of papers that demonstrate statins' anti-inflammatory effect. Yes it's true. If you shut off your immune system, you won't have any inflammation! Yet, scientists have known for at least a decade that statins have a dose-dependent immunosuppression effect.

1: J Heart Lung Transplant. 1998 Apr;17(4):335-40.

The inhibitory effects of pravastatin on natural killer cell activity in vivo and
on cytotoxic T lymphocyte activity in vitro.

Katznelson S, Wang XM, Chia D, Ozawa M, Zhong HP, Hirata M, Terasaki PI,
Kobashigawa JA.

Division of Nephrology, University of California, Davis, School of Medicine,
Sacramento, USA.

BACKGROUND: We have reported that heart transplant recipients treated with pravastatin demonstrate decreases in the incidence of clinically severe acute rejection episodes, the incidence and progression of transplant coronary vasculopathy, and natural killer cytotoxicity. These patients also exhibited a significant improvement in 1-year allograft survival. Because of these clinical findings suggesting an immunosuppressive effect of pravastatin unique to transplant recipients and the unclear role of natural killer cells in allograft rejection, we postulated that pravastatin may exert its immunomodulatory effect by acting with cyclosporine to alter T lymphocyte function. METHODS: Twenty patients randomized into an ongoing trial of pravastatin after heart transplantation were monitored serially for natural killer cell cytotoxicity. In a separate experiment, lymphocytes isolated from normal volunteers were treated with various combinations of pravastatin and cyclosporine and tested for cytotoxic T lymphocyte toxicity in a one-way mixed lymphocyte reaction. RESULTS: Pravastatin-treated heart transplant recipients exhibited a decrease in natural killer cell cytotoxicity (9.8% mean natural killer cell cytotoxicity vs 22.1% in the control group, p < 0.01). In the one-way mixed lymphocyte reaction with blood obtained from control subjects, there was a synergistic inhibition of cytotoxic T lymphocyte activity when the cells were cultured in a combination of pravastatin and cyclosporine (20.3% mean cytotoxicity of target cells vs 41.4% in the control group, p < 0.01). CONCLUSIONS: Pravastatin exerts an immunosuppressive effect in heart transplant recipients as expressed by a reduction in rejection and natural killer cell cytotoxicity. Pravastatin and cyclosporine act synergistically to reduce cytotoxic T lymphocyte activity. This synergistic effect of pravastatin and cyclosporine may explain why this immunosuppressive effect is unique to transplant recipients.


PMID: 9588577 [PubMed - indexed for MEDLINE]

1: Drugs. 2002;62(15):2185-91.

HMG-CoA reductase inhibitors as immunomodulators: potential use in transplant
rejection.

Raggatt LJ, Partridge NC.

Department of Physiology and Biophysics, Robert Wood Johnson Medical School,
University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854,
USA.

The benefit of HMG-CoA reductase inhibitors (statins) to the cardiovascular system is now well established and these drugs are being used extensively to treat hypercholesterolaemia clinically. However, as clinical outcomes become available it appears that statins are proving more beneficial than expected and thus it is being proposed that the actions of statins go beyond their ability to lower serum cholesterol levels. The report that statins can interact directly with lymphocyte function-associated antigen (LFA)-1 and prevent it engaging with the intracellular adhesion molecule (ICAM)-1 receptor on T cells is a novel mechanism of statin action and provides convincing evidence that these compounds can regulate biological systems other than by the cholesterol synthesis pathway. Immunosuppression to prevent organ transplant rejection is one application for which statins are currently being assessed. The clinical evidence is conflicting and does not convincingly reflect whether statins are beneficial as immunomodulators. However, in vivo studies investigating the cellular actions of statins have identified two mechanisms by which statins can potentially modulate an in vivo immune response. Firstly, statins regulate inducible class II major histocompatibility complex (MHC) expression on macrophages and endothelial cells. Secondly, statins can inhibit LFA-1 adhesion to ICAM-1 and thus regulate T cell activation. These findings suggest that statins have the potential to regulate an immune response in vivo and that more investigation is essential in order to explain the opposing clinical data.


PMID: 12381218 [PubMed - indexed for MEDLINE]

1: Atheroscler Suppl. 2002 May;3(1):17-20.

Immunosuppressive effects of statins.

Mach F.

Medicine Department, Cardiology Division, Foundation for Medical Research, Geneva
Medical School, University Hospital, 64 Avenue Roseraie, 1211 Geneva,
Switzerland.

3-Hydroxy-3-methhylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, are effective lipid lowering agents, extensively used in medical practice [Circulation 2000;101:207; J Am Med Assoc 2000;283:2935]. Statins have never been shown to be involved in the immune response, although reports have suggested a better outcome of cardiac transplantation in patients under pravastatin therapy [New Engl J Med 1995;333:621; Circulation 1997;96:1398]. Major histocompatibility complex class II (MHC class II) molecules are directly involved in the activation of T lymphocytes and in the control of the immune response. Whereas only a limited number of specialized cell types express MHC-II constitutively, numerous other cells become MHC-II positive upon induction by interferon-gamma (IFN-gamma) [Annu Rev Immunol 1996;14:301]. This complex regulation is under the control of the transactivator CIITA [Science 1994;265:106]. Recently, we demonstrated that statins act as direct inhibitors of induction of MHC-II expression by IFN-gamma and thus as repressors of MHC-II-mediated T cell activation [Nat Med 2000;6:1399; Swiss Med Wkly 2001;131:41]. This effect of statins is due to inhibition of the inducible promoter IV of the transactivator CIITA. Interestingly, this inhibition is specific for inducible MHC-II expression and does not concern constitutive expression of CIITA and MHC-II. In repressing induction of MHC-II, and subsequent T lymphocyte activation, statins therefore behave as a novel type of immunomodulator. This unexpected effect provides a scientific rationale for suggesting the use of statins as novel immunosuppressors, not only in organ transplantation but in numerous other pathologies as well.


PMID: 12044581 [PubMed - indexed for MEDLINE]

1: Swiss Med Wkly. 2001 Jan 27;131(3-4):41-6.

The HMG-CoA reductase inhibitor simvastatin inhibits IFN-gamma induced MHC class
II expression in human vascular endothelial cells.

Kwak B, Mulhaupt F, Veillard N, Pelli G, Mach F.

Cardiology Division, Department of Medicine, University Hospital, Geneva Medical
School, Foundation for Medical Research, Geneva, Switzerland.

HMG-CoA reductase inhibitors, or statins, are lipid-lowering agents that have been shown to effectively decrease severe rejection periods and development of transplant coronary artery disease after heart transplantation. Precise regulation of major histocompatibility complex class II (MHC class II) gene expression plays a pivotal role in control of the immune response after transplantation. The aim of this study was to evaluate the potential role of HMG-CoA reductase inhibitors in regulating the immune response. We have examined the effects of simvastatin on MHC class II expression in primary human endothelial cells. Using RNAse protection assay and flow cytometry, we observed that simvastatin dose-dependently reduced interferon-gamma (IFN-gamma) induced MHC class II expression (mRNA and protein). In contrast, simvastatin did not affect the expression of MHC class I, pointing to specific actions in the MHC class II signalling cascade. The transcriptional coactivator CIITA is the general regulator of both constitutive and inducible MHC class II expression. After stimulation with IFN-gamma, the CIITA gene is selectively activated via one (promotor IV) of its four promoters. Interestingly, mRNA levels of CIITA were decreased after treatment with simvastatin. In addition, using transient transfections of promoter-reporter constructs we observed that the activity of CIITA promoter IV was decreased by simvastatin. In conclusion, simvastatin selectively decreases IFN-gamma-induced MHC class II expression in human primary endothelial cells through actions on the CIITA promoter IV. Thus, the beneficial effects of statins reported after heart transplantation may result from this immunosuppressive action, suggesting possible therapeutic use for other immunological disorders as well.


PMID: 11219190 [PubMed - indexed for MEDLINE]

1: Cancer Immunol Immunother. 2009 Mar;58(3):461-7. Epub 2008 Jun 4.

Potential immunologic effects of statins in cancer following transplantation.

Fildes JE, Shaw SM, Williams SG, Yonan N.

The Transplant Centre, University Hospital of South Manchester NHS Foundation
Trust, Wythenshawe Hospital, Manchester, UK. james.fildes@manchester.ac.uk

3-hydroxy-3-methyglutaryl CoA reductase inhibitors (statins) are frequently used following organ transplantation and have well reported pleiotropic effects, including immunomodulation, which may be of benefit in preventing graft rejection. However, the immunomodulatory effects of statins on cell transformation and malignancy, combined with the immunologic processes and administration of immunosuppression are almost completely unknown. The administration of immunosuppression is well recognised as the main cause of cancer following transplantation, so the addition of an immunomodulatory agent should be associated with an increased incidence of cancer, as immune surveillance and response may be suppressed, allowing cellular transformation and proliferation combined with lack of recognition to occur. This hypothetical review attempts to delineate the mode of action of statins in terms of pro/anti-carcinogenic mechanisms, while considering graft rejection and the presence of immunosuppression.


PMID: 18523769 [PubMed - indexed for MEDLINE]