Antiphospholipid syndrome (APS) can affect any vascular bed and is characterised by a plethora of clinical manifestations related with different organ systems involvement. Accordingly, APS can affect any part of kidney vasculature and parenchyma such as renal arteries and veins, intra-renal arteries and arterioles, and glomerular capillaries. APS-associated nephropathy was first described in patients with primary APS, characterised by acute thrombotic lesions in glomeruli and/or arterioles (thrombotic microangiopathy) and chronic vascular lesions such as fibrous intimal hyperplasia of arterioles and interlobular arteries, organised thrombi with or without recanalisation, and fibrous arterial and arteriolar occlusions or focal cortical atrophy.¹ APS nephropathy lesions have also been later described in patients with SLE-associated APS and SLE patients with positive antiphospholipid antibodies but without APS, independently of lupus nephritis.^{2, 3} The most common clinical manifestations of APS nephropathy include hypertension, microscopic hematuria, proteinuria (from mild to nephrotic range), and a usually mild renal insufficiency. Arterial thromboses (especially stroke), pulmonary embolism, livedo reticularis, anticardiolipin antibodies, and lupus anticoagulant were strongly associated with histologic lesions of APS nephropathy. During the follow-up period, manifestations of APS (especially arterial thromboses) developed more frequently in SLE/non-APS patients with APS nephropathy than in those without APS nephropathy lesions. In the Sydney classification criteria for APS, APS nephropathy has been included in non-criteria APS manifestations.⁴ The significant association between the presence of APS nephropathy and antiphospholipid antibodies suggests a pathogenetic role of antiphospholipid antibodies in the development of this nephropathy. Data from experimental and clinical studies support also a potential role of complement cascade activation, tissue factor activation, and activation of mTORC in APS nephropathy pathogenesis. Currently, there is no consensus on the treatment of APS nephropathy. Updated evidence about the role of anticoagulation, hydroxychloroquine, statins, and targeted therapies such as B-cell directed therapies, complement inhibition, tissue factor inhibition, and mTOR pathway inhibition will be discussed.

References [1] Nochy D, Daugas E, Droz D, et al. The intrarenal vascular lesions associated with primary antiphospholipid syndrome. J Am Soc Nephrol1999;10:507–518.

[2] Daugas E, Nochy D, Huong du LT, et al. Antiphospholipid syndrome nephropathy in systemic lupus erythematosus. J Am Soc Nephrol2002;13:42–52.

[3] Tektonidou MG, Sotsiou F, Nakopoulou L, et al. Antiphospholipid syndrome nephropathy in patients with systemic lupus erythematosus and antiphospholipid antibodies: prevalence, clinical associations, and long-term outcome. Arthritis Rheum2004;50:2569–2579.

[4] Miyakis S, Lockshin MD, Atsumi T, Branch DW, Brey RL, Cervera R, Derksen RH, DE Groot PG, Koike T, Meroni PL, Reber G, Shoenfeld Y, Tincani A, Vlachoyiannopoulos PG, Krilis SA. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost2006;4:295–306.

Disclosure of Interest None declared