Role of antiphospholipid antibodies in kidney disease: Risk factors, immunopathogenesis, and diagnosis

Antiphospholipid antibodies (aPLs) are a heterogeneous group of autoantibodies that include anticardiolipin antibodies, anti-β2 glycoprotein I antibodies, and lupus anticoagulant. The presence of aPLs is the main characteristic feature of antiphospholipid syndrome (APS), an autoimmune disease with multifactorial etiology. Kidney involvement is a well-recognized complication associated with both primary and secondary APS. Kidney involvement in APS presents with renal artery thrombosis, renal vein thrombosis, allograft loss due to thrombosis after kidney transplantation, and injury to the renal microvasculature, also known as APS nephropathy (APSN). APSN is the characteristic manifestation of kidney involvement in APS and occurs as a result of vaso-occlusive disease in the intrarenal vasculature. Diagnosis and risk stratification of APS are complex and still evolving. This review synthesizes and updates the available evidence in literature regarding risk factors, pathogenesis, and diagnosis of APS and APSN.