Beta2-glycoprotein I Expression in Lupus Nephritis Patients with Antiphospholipid-associated Nephropathy.

OBJECTIVE: Antiphospholipid-associated nephropathy (aPLN) is a severe condition in patients with lupus nephritis (LN). aPLN should be distinguished from other reasons for renal ischemia. The most important cofactor of antiphospholipid antibodies (aPL), β2-glycoprotein I (β2GPI), was shown in vitro to bind endothelial cells and to induce a procoagulant phenotype. The objectives of this study were to investigate whether β2GPI expression was involved in patients with LN with aPLN and to determine its specificity.

METHODS: We retrospectively investigated β2GPI expression in 231 renal biopsy specimens of patients with LN. Data from biopsy reports and clinical information were collected. Immunohistochemical staining for β2GPI expression was performed.

RESULTS: Histological aPLN was detected in 88 patients with LN (38.1%). The LN with aPLN consisted of 43 patients (18.6%). Expression of β2GPI was detected in endothelial cells in 14 (32.6%) in renal arteries or arterioles, 11 (25.6%) in glomerular or peritubular capillaries, and a total of 15 (34.9%) of the 43 patients with LN with aPLN. It was mainly expressed in the endothelial cells in patients with LN with aPLN (p < 0.05). The specificity of β2GPI expression in patients with LN with aPLN was 97.5%.

CONCLUSION: Expression of β2GPI may be involved in the formation of aPLN in patients with LN. This expression in endothelial cells in kidney tissue may be considered a useful marker for aPLN.