Caveolin-1 as a Marker of Endothelial Damage in Primary Antiphospholipid Syndrome Nephropathy.

RATIONALE &

OBJECTIVE

Thrombotic microangiopathy (TMA) as seen in antiphospholipid syndrome nephropathy (APSN) is associated with poor kidney outcomes. Caveolin-1 (Cav-1) has emerged as a potential marker of endothelial damage and microvascular injury.

STUDY

DESIGN

This retrospective study investigates the diagnostic potential value of Cav-1 immunohistochemistry in APSN-related TMA.

SETTING &

PARTICIPANTS

Patients were retrieved from the Piedmont and Aosta Valley Rare Disease Registry, from which a total of 771 APS cases had been recorded.

EXPOSURE: Only case with biopsy-proven renal involvement were included.

OUTCOMES: Cases were classified into three histopathological clusters: TMA (APSN-TMA), hyperplastic vasculopathy, and subendothelial edema. Immunohistochemical staining for Cav-1 was performed and graded based on expression in peritubular and glomerular capillaries.

ANALYTICAL APPROACH: Clinical and laboratory data, including antiphospholipid antibody profiles, were correlated with Cav-1 expression.

RESULTS

Out of 771 patients with APS, a total of 11 patients with primary APS and renal involvement were retrieved (1.43%). APSN-TMA was identified in 7 (63.3%) cases, hyperplastic vasculopathy in 2 (18.1%), and subendothelial edema in 2 (18.1%). Cav-1 expression was significantly higher in APSN-TMA cases in both glomerular (P < 0.001) and peritubular (P < 0.05) capillaries compared with other clusters, with 5 of 7 APSN-TMA cases exhibiting diffuse (grade III) staining. Triple antiphospholipid antibody positive testing was more prevalent in APSN-TMA cases, reinforcing their distinct pathophysiological profile.

LIMITATIONS: The small sample size warrants validation in larger cohorts, and Cav-1 expression, although associated with APSN, might not be disease-specific.

CONCLUSIONS

APSN-TMA is a rare manifestation of a rare disease. Cav-1 is strongly associated with APSN-TMA and may serve as a novel marker for its diagnosis and stratification. Given the poor renal prognosis of APSN-TMA, identifying affected patients is crucial for optimizing management strategies.