Membrane endothelial protein C receptor expression in renal tissue of pediatric lupus nephritis patients

Background: Lupus nephritis (LN) is more common and more severe is pediatric systemic lupus erythematosus (pSLE). Endothelial protein C receptor (EPCR) is an inducer of anti-apoptotic pathways in endothelial cells. Recent studies have taken elevated anti-injury biomarkers as EPCR into consideration regarding their roles to antagonize LN. Objectives: to evaluate the membrane expression of endothelial protein C receptor (mEPCR) in the renal microvasculature in pediatric patients with LN. Methods: This study was conducted on 25 patients with pSLE following up at the Allergy and Immunology Clinic, Children’s Hospital, Ain Shams University. The 25 patients have LN proved by a previous renal biopsy. Medical history, clinical examination and routine laboratory investigations for assessment of disease activity were done for all patients. Paraffin blocks of patients’ renal biopsies were subjected to immunohistochemistry staining for the frequency of mEPCR. Results: mEPCR was mainly expressed in the endothelium of the peritubular capillaries. Our results showed that an equal number of patients had nil and mild marker expression (8 patients each, 32%) while 9 patients (36%) showed moderate/strong marker expression. We found that 9 out of 10 (90%) of patients with class II had nil/mild marker expression, 5 patients out of 9 (55.5%) with class III had mild/moderate marker expression, while 5 patients 0ut of 6 (83.3%) with class IV and V had moderate/strong marker expression. We only found a significant statistical difference between the different degrees of mEPCR expression regarding 24 hours urinary proteins. No statistical significance was found between the different degrees of mEPCR expression and different immuno-suppressive therapy dose/kg or renal outcome using the renal British Isles Lupus Assessment Group (BILAG) score; in spite that most of the patients who got improved had nil/mild marker expression. Conclusion: mEPCR -bearing a statistically significant difference in relation to different LN classes- showed more expression in the more aggressive classes; a finding which might suggest a contribution of the endothelium of the renal parenchyma to the pathophysiology of more progressive LN. Hence the tissue marker might emerge as a potential new therapeutic target in the search for more selective treatment for SLE. Keywords: p SLE, mEPCR, renal biopsy, immunohistochemistry, BILAG, lupus nephritis