Central nervous system infections - A potential complication of systemic immunotherapy

Purpose of review: Multiple sclerosis is a chronic inflammatory disease of the central nervous system, characterized by demyelination and axonal damage. With the emergence of more efficient immune therapies, severe sometimes even fatal central nervous system infections were observed. This review will address the role of the systemic immune system in central nervous system immune surveillance and discuss implications for the development of novel immunotherapies in multiple sclerosis. Recent findings: In the last decade, a number of immunosuppressive and immunomodulatory agents have been approved for the treatment of multiple sclerosis, based on the results of double-blind placebo-controlled randomized clinical trials. A better understanding of the pathogenesis of the disease has prompted exploration of the therapeutic utility of new drugs that more potently disrupt the pathophysiological cascade of events that culminates in central nervous system tissue damage. One potential side-effect of these newer therapies is their interference with the control of central nervous system infections by the immune system. Summary: Any increase in potency of multiple sclerosis therapies could well interfere with protective immunosurveillance of the central nervous system. One possible outcome is an increased incidence of opportunistic infections. A heightened vigilance for central nervous system infections in the setting of immunosuppression is necessary to prevent serious side-effects in the future.