Systemic lupus erythematosus and infections

Systemic lupus erythematosus (SLE) is an inflammatory and multi-systemic autoimmune disorder, characterized by an uncontrolled auto-reactivity of B and T lymphocytes, leading to the production of autoantibodies against self-directed antigens and tissue damage. The life expectancy in patients with SLE has improved tremendously in the last two decades, but the mortality rates still remain three times greater compared to those of the general population. Despite increased awareness and improved management, infections remain a major source of morbidity, mortality, hospitalization, and death in patients with SLE. The infections in SLE patients widely range from opportunistic to common bacterial and viral infections with typical or atypical presentations. Moreover, SLE patients exhibit an increased susceptibility to hospital-acquired infections. Factors associated with increased risk of infections include high disease activity, specific immune dysregulation, drug-induced immune deficiency, and organ failure with irreversible damage. Furthermore, immunosuppressive agents may make patients more susceptible to opportunistic infections. A big challenge faced by physicians in these patients is to distinguish between infections and flares of SLE, as infections may mimic them, leading to predicament in diagnosis and appropriate management. Immunosuppression used to treat severe flares of lupus can have catastrophic complications in patients with active infections. There is an urgent need for biomarkers to make an accurate differential diagnosis in this situation. In spite of increased understanding of SLE, many questions remain unanswered. Further research is needed to determine specific immune dysregulation underlying the increased susceptibility to specific infections, predictors of infection in SLE such as genetic markers, and biomarkers that discriminate between disease activity and active infections. Also, measures must be evaluated appropriately to prevent infections, and their complications in SLE.