Prevention of chronic renal allograft rejection by AS2553627, a novel JAK inhibitor, in a rat transplantation model

Background Janus kinase (JAK) inhibitors are thought to be promising candidates to aid renal transplantation. However, the effectiveness of JAK inhibitors against features of chronic rejection, including interstitial fibrosis/tubular atrophy (IF/TA) and glomerulosclerosis, has not been elucidated. Here, we investigated the effect of AS2553627, a novel JAK inhibitor, on the development of chronic rejection in rat renal transplantation. Methods Lewis (LEW) to Brown Norway (BN) rat renal transplantation was performed. Tacrolimus (TAC) at 0.1 mg/kg was administered intramuscularly once a day for 10 consecutive days starting on the day of transplantation (days 0 to 9) to prevent initial acute rejection. After discontinuation of TAC treatment from days 10 to 28, AS2553627 (1 and 10 mg/kg) was orally administered with TAC. At 13 weeks after renal transplantation, grafts were harvested for histopathological and mRNA analysis. Creatinine and donor-specific antibodies were measured from plasma samples. Urinary protein and kidney injury markers were also evaluated. Results AS2553627 in combination with TAC exhibited low plasma creatinine and a marked decrease in urinary protein and kidney injury markers, such as tissue inhibitor of metalloproteinase-1 and kidney injury molecule-1. At 13 weeks, histopathological analysis revealed that AS2553627 treatment inhibited glomerulosclerosis and IF/TA. In addition, upregulation of cell surface markers, fibrosis/epithelial–mesenchymal transition and inflammation-related genes were reduced by the combination of AS2553672 and TAC, particularly CD8 and IL-6 mRNAs, indicating that AS2553627 prevented cell infiltration and inflammation in renal allografts. Conclusions These results indicate the therapeutic potential of JAK inhibitors in chronic rejection progression, and suggest that AS2553627 is a promising agent to improve long-term graft survival after renal transplantation.