Statins induce immunosuppressive effect on heterotopic limb allografts in rat through inhibiting T cell activation and proliferation

Statin Modulation of Human T-Cell Proliferation, IL-1β and IL-17 Production, and IFN-γ T Cell Expression: Synergy with Conventional Immunosuppressive Agents

HMG-CoA reductase inhibitors (statins) have been demonstrated to be immunomodulatory for human immune-mediated disease and in experimental models. The aim of this study was to compare statin-mediated immunosuppressive effects on human T-cell responses in vitro with those of conventional immunosuppressives (dexamethasone, cyclosporin A (CsA), mycophenolate, and rapamycin). Statins (atorvastatin, lovastatin, and simvastatin) were investigated for their modulatory effects on human PBMC viability, cytokine profiles, and T-cell proliferation. At concentrations that inhibited anti-CD3/28-stimulated T-cell proliferation (P < 0.01), simvastatin significantly decreased intracellular CD4(+) T-cell expression of IFN-γ (P < 0.01) to levels similar to those induced by conventional immunosuppressives. Atorvastatin and lovastatin also decreased IFN-γ expression, although to a lesser degree (P < 0.05). All three statins reduced levels of IL-17 production (P < 0.01). However, in response to anti-CD3/28 stimulation, simvastatin significantly upregulated IL-1β production (P < 0.05). The profile of cytokines produced in response to anti-CD3/28 stimulation was similar when both atorvastatin and dexamethasone were added as compared with dexamethasone alone, suggesting that atorvastatin can synergise with dexamethasone with respect to immunomodulation of cytokines. This data supports the hypothesis of selective statin-mediated immunomodulatory effects on human immune cells.

Biomarker assessment of the immunomodulator effect of atorvastatin in stable renal transplant recipients and hypercholesterolemic patients

BACKGROUND

HMG-CoA reductase inhibitors (statins) have effects beyond lipid lowering, including immunomodulatory and anti-inflammatory properties. Statins are frequently combined with immunosuppressive agents in transplant recipients to modulate the hyperlipidemic side effects of the immunosuppressants. However, the role of statins in the immunosuppressive response that is achieved in individual patients remains to be assessed.

OBJECTIVE

The aim of this study was to evaluate the immunomodulatory effect of atorvastatin given alone and in combined treatment with tacrolimus and mycophenolate mofetil.

STUDY DESIGN

Two patient groups were studied: renal transplant recipients receiving tacrolimus and mycophenolate mofetil therapy, and hypercholesterolemic patients (the control group). Fasting blood samples were taken from participants before and 1 month after atorvastatin treatment was started to study a small battery of biomarkers that are able to reflect the range of the effects of immunosuppressive therapy and atorvastatin.

SETTING

All patients in the study were enrolled at the Hospital Clinic of Barcelona.

PATIENTS

All patients enrolled in the study were candidates for treatment with atorvastatin because of high cholesterol levels. One group consisted of 25 stable renal transplant recipients with low-density lipoprotein (LDL) cholesterol levels above 100 mg/dL after 3 months of therapeutic lifestyle changes, according to the guidelines of the National Kidney Foundation - Kidney Disease Outcomes Quality Initiative. The other group included 25 hypercholesterolemic patients with LDL cholesterol levels above target values for the patients' overall risk, as derived from the National Cholesterol Education Program Adult Treatment Panel III criteria.

INTERVENTION

Atorvastatin (Lipitor®) treatment was started at a fixed dose of 20 mg daily.

MAIN OUTCOME MEASURE

The studied biomarkers were lymphocyte proliferation, intracellular adenosine triphosphate (ATP) synthesis in CD4+ T cells, intralymphocytary cytokine expression (interleukin [IL]-2, interferon [IFN]-γ), soluble cytokine production (IL-2, IFN-γ, IL-10, IL-17, and transforming growth factor-β) and regulatory T (T(reg)) cells.

RESULTS

Atorvastatin proved to be an immunomodulatory agent, significantly decreasing lymphocyte proliferation by 15% (p = 0.001), increasing ATP levels by 16% (p = 0.0004), and showing a trend toward increasing T(reg) cells in hypercholesterolemic patients (p = 0.09). In the renal transplant recipients, atorvastatin therapy did not modify any of the biomarkers of immunosuppression that were studied.

CONCLUSION

Atorvastatin showed immunoregulatory effects on T cells in hypercholesterolemic patients. These effects were absent in renal transplant recipients, suggesting that the beneficial effects of atorvastatin in this patient group do not relate to immunoregulation. Therefore, statin treatment cannot be considered as a means to reduce the dose of immunosuppressive agents.

Biomarker assessment of the immunomodulator effect of atorvastatin in stable renal transplant recipients and hypercholesterolemic patients

BACKGROUND

HMG-CoA reductase inhibitors (statins) have effects beyond lipid lowering, including immunomodulatory and anti-inflammatory properties. Statins are frequently combined with immunosuppressive agents in transplant recipients to modulate the hyperlipidemic side effects of the immunosuppressants. However, the role of statins in the immunosuppressive response that is achieved in individual patients remains to be assessed.

OBJECTIVE

The aim of this study was to evaluate the immunomodulatory effect of atorvastatin given alone and in combined treatment with tacrolimus and mycophenolate mofetil.

STUDY DESIGN

Two patient groups were studied: renal transplant recipients receiving tacrolimus and mycophenolate mofetil therapy, and hypercholesterolemic patients (the control group). Fasting blood samples were taken from participants before and 1 month after atorvastatin treatment was started to study a small battery of biomarkers that are able to reflect the range of the effects of immunosuppressive therapy and atorvastatin.

SETTING

All patients in the study were enrolled at the Hospital Clinic of Barcelona.

PATIENTS

All patients enrolled in the study were candidates for treatment with atorvastatin because of high cholesterol levels. One group consisted of 25 stable renal transplant recipients with low-density lipoprotein (LDL) cholesterol levels above 100 mg/dL after 3 months of therapeutic lifestyle changes, according to the guidelines of the National Kidney Foundation - Kidney Disease Outcomes Quality Initiative. The other group included 25 hypercholesterolemic patients with LDL cholesterol levels above target values for the patients' overall risk, as derived from the National Cholesterol Education Program Adult Treatment Panel III criteria.

INTERVENTION

Atorvastatin (Lipitor®) treatment was started at a fixed dose of 20 mg daily.

MAIN OUTCOME MEASURE

The studied biomarkers were lymphocyte proliferation, intracellular adenosine triphosphate (ATP) synthesis in CD4+ T cells, intralymphocytary cytokine expression (interleukin [IL]-2, interferon [IFN]-γ), soluble cytokine production (IL-2, IFN-γ, IL-10, IL-17, and transforming growth factor-β) and regulatory T (T(reg)) cells.

RESULTS

Atorvastatin proved to be an immunomodulatory agent, significantly decreasing lymphocyte proliferation by 15% (p = 0.001), increasing ATP levels by 16% (p = 0.0004), and showing a trend toward increasing T(reg) cells in hypercholesterolemic patients (p = 0.09). In the renal transplant recipients, atorvastatin therapy did not modify any of the biomarkers of immunosuppression that were studied.

CONCLUSION

Atorvastatin showed immunoregulatory effects on T cells in hypercholesterolemic patients. These effects were absent in renal transplant recipients, suggesting that the beneficial effects of atorvastatin in this patient group do not relate to immunoregulation. Therefore, statin treatment cannot be considered as a means to reduce the dose of immunosuppressive agents.

In Vitro Studies of the Immunomodulatory Effects of Statins Alone and in Combination with Immunosuppressive Drugs

The effects of statins go beyond their lipid-lowering properties and include immunomodulatory and anti-inflammatory effects. Unfortunately, there is a lack of in vitro assays that study the immunomodulatory effect of statins at therapeutic concentrations and the possible synergism with immunosuppressive drugs. Besides, they are mostly evaluated on isolated peripheral blood mononuclear cells instead of using whole blood as a matrix. The aim of this study is to perform in vitro experiments to evaluate the effect of atorvastatin, simvastatin and fluvastatin at therapeutic concentrations alone and in combination with everolimus or tacrolimus on immunosuppressive response, using whole blood as a matrix by investigating lymphocyte proliferation and production of the soluble cytokines interleukin (IL)-2, IL-10 and interferon (IFN)-γ. Statins (0.1 μM) inhibited T cell proliferation by 12–16% in a dose-dependent manner and when statins at 0.1 μM were combined with each immunosuppressive drug at 8 ng/ml, inhibition increased by 6–9% (p<0.05) for everolimus and 8–15% (p<0.05) for tacrolimus, but not for atorvastatin. At a dose of 0.1 μM, all three statins inhibited soluble IFN-γ production by approximately 5–9% (p<0.02). IL-2 and IL-10 production were unaltered by the presence of statins. These findings suggest that statins seem to exert a mild anti-inflammatory effect that might potentially be used to treat autoimmune diseases.