Systemic lupus erythematosus and diffuse alveolar hemorrhage, etiology and novel treatment strategies

Diffuse alveolar hemorrhage is a severe respiratory complication of systemic lupus erythematosus. The illness develops over hours to a few days and is the systemic lupus erythematosus-associated syndrome with highest mortality. Although no specific symptoms have been identified, a number of features are associated with diffuse alveolar hemorrhage, with a drop in blood hemoglobin the most prominent. Dyspnea, blood-stained sputum, diffuse infiltrates identified by chest imaging, elevated single breath-diffusing capacity for monoxide, thrombocytopenia and C3 hypocomplementemia are other commonly reported signs of diffuse alveolar hemorrhage. The etiology is not completely understood but many patients develop diffuse alveolar hemorrhage concomitant with lupus nephritis, suggesting immune complex-driven pathology. Biopsy studies have identified both cases with capillaritis and a bland non-inflammatory phenotype. An animal model of diffuse alveolar hemorrhage has indicated requirement of B lymphocytes and complement receptor-mediated apoptotic body phagocytosis by monocytes as part of the pathogenesis. This review will discuss considerations when diagnosing the condition and available therapies. Infections and other causes of hemorrhage have to be excluded as these require different treatment strategies. Methylprednisolone and cyclophosphamide remain the most commonly used therapies. Plasmapheresis and rituximab are other beneficial treatment options. A few studies have also considered intrapulmonary Factor VII therapy, extracorporeal membrane oxygenation and mesenchymal stem cell therapy. There is an unmet need of better definition of diffuse alveolar hemorrhages etiology and pathology for development of improved treatment strategies.