Syndecan-1 (CD138) immunohistochemical expression patterns in lupus nephritis; reflections on different clinicopathological parameters

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Introduction : Syndecan 1 (SCD1) is a lectin expressed at the surface of renal tubular epithelial cells and plasma cells. In epithelial cells, cell surface syndecan1 is cleaved by inflammation-induced proteases (eg, ADAMTS, MMP), since loss of cell surface syndecan1 is associated with higher susceptibility to cell damage. Objectives : To explore a potential additional value of SCD1 immunohistochemical expression in lupus nephritis specimens of different ISN/RPS classes and NIH activity and chronicity indices. Patients and Methods: This retrospective study included 50 renal biopsy specimens diagnosed as lupus nephritis at the pathology laboratory, and electron microscopy (EM) laboratory of Ain-Shams University specialized hospitals. Data were collected from records as personal data, medical history and laboratory results including serum creatinine and proteinuria. Immunohistochemical expression of syndecan-1 was evaluated in renal tubular epithelial cells (TECs) followed by correlation with different clinicopathological parameters. Results : Fifty renal biopsy specimens with lupus nephritis including 14 cases of class II, 4 cases of class III, 20 cases of class IV and 12 cases of class V were re-evaluated. The mean serum creatinine was 1.57 ± 0.67 mg/dL. Nine cases (18%) were negative for proteinuria, while 41 cases (82%) were presented with proteinuria with a mean of 1.5 ± 0.9 g/24 h. There was no statistically significant difference in the percentage of SCD-1 expression with different lupus classes. Serum creatinine and albumin showed a statistically significantly different correlation with semiquantitative score of SCD-1 expression. The highest value of creatinine detected with score 1 of SCD-1 expression (P=0.038) and the highest value of urinary albumin was recorded with score 1 of SCD-1 expression. Accordingly, the lowest mean of urinary albumin recorded in SCD-1 score 3 (P<0.001). There was a weekly negative association between loss of SCD-1 expression and increased NIH activity and chronicity indices. Conclusion : Loss of syndecan immunohistochemical expression in renal TECs in lupus nephritis is highly associated with proteinuria and elevated serum creatinine and can be used as a predictive marker for disease severity and progression.