A group of doctors has called for studies into the possible effects of the lipid-lowering statin drugs on the immune system in HIV-positive patients, in a letter published in the 1st August edition of The Journal of Acquired Immune Deficiency Syndromes.
The doctors, from the University of Miami School of Medicine, explain that that statins may affect the levels of immune cells and chemical messengers or ‘cytokines’ in the body, potentially altering the course of HIV disease or therapy.
Their concern is heightened by the increasing numbers of patients who are taking statins to treat elevations in blood fat levels and reduce the risk of cardiovascular disease caused by HIV treatment.
The letter’s authors report that one study examining patients with angina found that the use of statins decreased the ratio of two subtypes of CD4 T-cells after 16 weeks. There is evidence that changes in the levels of the cytokines released by these cells, including interleukin-2 and interferon-gamma, also occur during the course of HIV infection.
Importantly, the relative levels of these types of cell may play a crucial role in body’s ability to keep HIV levels under control during the chronic phase of infection.
Statins are also being tested for the treatment of conditions that involve the immune system, because of their perceived immunological effects. These include multiple sclerosis and rejection reactions to certain types of transplant.
The doctors cite evidence from HIV-positive patients. “Small studies have suggested that the use of statins is associated with lower absolute CD4 T-cell responses after six, twelve and 18 months of treatment in HIV-infection patients on protease inhibitor-based highly active antiretroviral therapy,” they explain.
Furthermore, they warn that the effects of statins may be difficult to detect using CD4 cell counts, which may not fully reflect the functioning of the immune system.
“Whether these observations translate into significant clinical interactions is uncertain, and no doubt exists about the beneficial effects of statins in the management of dyslipidaemia and atherosclerotic disease, but we believe that possible long-term immunologic effects should remain a consideration when statins are used in HIV-infected individuals on HAART,” they write.
“This group of patients deserves particularly close evaluation in the future.”
Corrales-Medina VF et al. Statins and HIV: beyond the metabolic and cardiovascular benefit. J Acquir Immune Defic Syndr 39: 503-504, 2005.