Insights into the pathogenesis of catastrophic antiphospholipid syndrome. A case report of relapsing catastrophic antiphospholipid syndrome and review of the literature on ischemic colitis.

We present the case of a woman with a severe clinical history of antiphospholipid syndrome and persistent positivity for lupus anticoagulant, IgG anticardiolipin and IgG anti-β2Glycoprotein I antibodies. An acute clinical onset characterized by severe abdominal pain immediately followed by circulatory shock and histological colonic small vessel thrombosis pattern pointed to a diagnosis of ischemic colitis. The subsequent rapid onset of pulmonary alveolitis and heart failure associated to subendocardial hypoperfusion led to a diagnosis of definite catastrophic antiphospholipid syndrome (CAPS). Conventional triple therapy together with a broad-spectrum preventive antibiotic therapy were quickly initiated, and the outcome was favorable. We evaluated the patients with ischemic colitis in CAPS described in the literature between 1992 and May 2019 and our CAPS case. In accordance with the "two-hit" hypothesis and on the basis of the patients' data, we would like to speculate that the colonic wall necrosis related to ischemic colitis damaged the intestinal barrier causing loss of resistance to bacteria and leading to endotoxemia and bacteremia with bacteria translocation through the circulatory stream to the lungs and heart. The bacteria acted as the priming factor which favored the binding of β2Glycoprotein I to the endothelium vessels in the colon, lungs, and heart following activation of anti-β2Glycoprotein I antibodies which attached to the domain I of β2Glycoprotein I. This was followed by complement activation which triggered the thrombotic and cytokine storm. If further clinical studies confirm this hypothesis, the treatment of CAPS could be more targeted and effective.