#2691 GLOMERULAR LESIONS IN PATIENTS WITH ANTIPHOSPHOLIPID SYNDROME
Authors: Monova Daniela Valentinova , Todorov Todor , Monov Simeon 
Published: June 2023

Abstract

Background and Aims
Antiphospholipid syndrome (APS) is a complex autoimmune systemic disease, characterized by the presence of circulating antibodies directed against anionic phospholipids and the protein bound to them (aPL), leading to recurrent thrombosis and/or obstetrical complications. Renal manifestation of antiphospholipid syndrome conform a wide spectrum of disease renal syndrome. APS nephropathy (APSN) is considered a renal small-vessels vasculopathy, that can present acutely or chronically.
The aim of the study is to identify glomerular lesions in patients with APSN.

Method
We studied retrospectively 114 patients (51 male, 63 female; age between 19 and 58 years; duration of follow-up was between 2 and 16 years) fulfilling classification criteria for APS. Renal and extra-renal symptoms were analyzed. None of the patients developed SLE in follow up. 18 patients with evidence of renal involvement underwent renal biopsy. All cases had proteinuria and five of them presented nephrotic syndrome.

Results
Of 18 patients with kidney biopsy, 8 (44,44%) were male and 10 (55,56%) - female. Four of patients with renal biopsy had membranous glomerulonephritis, two had diffuse proliferative glomerulonephritis, 2 - mesangial C3 nephropathy, 2 - minimal change disease, 1- focal segmental glomerulosclerosis, the other seven had classic pathologic findings consistent with APSN. Chronic lesions with fibrous intimal hyperplasia being the most common. Thrombotic microangiopathy (TMA) in glomeruli was characterized by fibrin thrombi without inflammatory cells or immune complexes. Double contour of the glomerular basement membrane was associated with mesangiolysis and endothelial cell swelling in 5 patients with APSN. Electron microscopy confirmed subendothelial edema. Segmental glomerulosclerosis was observed in 4 patients. Tubulointerstitium was injured with interstitial fibrosis and tubular atrophy. Patients with APS and renal involvement were older (p&lt;0,05), had LA positive test (p&lt;0,005) and low complement levels (p&lt;0,05). Hypertension is present in all cases with APSN, reduced glomerular filtration rate – in 4. All cases had proteinuria and five of them presented with nephrotic syndrome. Microscopic hematuria is observed in 4 patients. The treatment of APSN includes standard anticoagulant treatment for APS, inhibitors of the angiotensin system in patients with hypertension and proteinuria, steroids, intravenous immunoglobulin, cyclophosphamide and azathioprine.

Conclusion
Of 18 patients with kidney biopsy, 8 (44,44%) were male and 10 (55,56%) - female. Four of patients with renal biopsy had membranous glomerulonephritis, two had diffuse proliferative glomerulonephritis, 2 - mesangial C3 nephropathy, 2 - minimal change disease, 1- focal segmental glomerulosclerosis, the other seven had classic pathologic findings consistent with APSN. Chronic lesions with fibrous intimal hyperplasia being the most common. Thrombotic microangiopathy (TMA) in glomeruli was characterized by fibrin thrombi without inflammatory cells or immune complexes. Double contour of the glomerular basement membrane was associated with mesangiolysis and endothelial cell swelling in 5 patients with APSN. Electron microscopy confirmed subendothelial edema. Segmental glomerulosclerosis was observed in 4 patients. Tubulointerstitium was injured with interstitial fibrosis and tubular atrophy. Patients with APS and renal involvement were older (p&lt;0,05), had LA positive test (p&lt;0,005) and low complement levels (p&lt;0,05). Hypertension is present in all cases with APSN, reduced glomerular filtration rate – in 4. All cases had proteinuria and five of them presented with nephrotic syndrome. Microscopic hematuria is observed in 4 patients. The treatment of APSN includes standard anticoagulant treatment for APS, inhibitors of the angiotensin system in patients with hypertension and proteinuria, steroids, intravenous immunoglobulin, cyclophosphamide and azathioprine.