#648 Relationship between renal tubular damage, interstitial fibrosis and semaphorin class 3C

Abstract Background and Aims The detailed mechanism of interstitial fibrosis in CKD has not been clarified. In this study, we focused on semaphorin class 3C (SEMA3C), a secreted protein expressed in the renal tubules, that is involved in embryonic kidney development [1], and investigated the relationship between SEMA3C and renal tubular damage and interstitial fibrosis. Methods < Clinical research> We investigated the correlation between serum SEMA3C concentration and the renal tubular damage marker urinary β2 microglobulin (β2MG) concentration in the 191 patients who underwent kidney biopsy from 2017 to 2021 at Yamagata University. < In vivo study> We generated proximal tubule-specific SEMA3C knockout mice (PT-SEMA3C KO) from male mice (C57BL/6) using the Cre/loxP system. The PT-SEMA3C KO group and control group were fed a 0.2% adenine diet for 5 weeks to induce CKD. The area of interstitial fibrosis/tubular atrophy (IFTA) region was assessed by Masson-Trichrome staining. Results < Clinical research> The median age of the patients was 54 (IQR 38-68) years, 94 men and 97 women. Median serum SEMA3C concentration was 0.14 (IQR 0.07-0.35) ng/ml. Median urinary β2MG levels was 0.22 (IQR 0-1.79) mg/gCr. Spearman's correlation analysis showed a significant negative correlation between serum SEMA3C and urinary β2MG levels (r=-0.208, P=0.005), but no correlation between eGFR and Urinary protein/ creatinine. < In vivo study> IFTA region was 5.6% in the control group, compared to 11.2% in the PT-SEMA3C KO group (p=0.031). Interstitial fibrosis was significantly suppressed in the PT-SEMA3C KO mice (Fig. 1). Conclusion Our clinical and in vivo results indicate that serum SEMA3C is associated with renal tubular damage and interstitial fibrosis.