201909Miyake

研究発表を行った学会；発生研サマーリトリート 2019
2019年 8月 7日〜8日（熊本県菊池市）
タイトル； Elucidation of the function of collagen receptor DDR2 in Alport syndrome mouse model.
発表者；三宮　裕也氏
（熊本大学　大学院薬学教育部　遺伝子機能応用学分野）
要旨；
Renal fibrosis is a critical process in the progression of chronic kidney disease (CKD). So, elucidation of the mechanism of renal fibrosis and the development of therapeutic agents that can block this process are being actively carried out. Type I collagen is an important factor in fibrogenesis, which activates tyrosine kinase receptor discoidin domain receptor (DDR). DDR is gaining attention as a regulatory molecule for fibrosis. It was reported that the deficiency of DDR1 isoform inhibits fibrosis in mice kidneys, and acts in a pathological protective manner in mouse models of hereditary renal disease Alport syndrome, obstructive nephropathy, and hypertension-induced nephropathy. This made DDR1 as a novel therapeutic target for CKD. Another DDR isoform, Ddr2, is less known, and it is also not known whether the DDR inhibitor is specific to Ddr1. In this study, I examined the involvement of DDR2 in renal dysfunction using Alport syndrome (AS) mouse model with stable CKD. First, I measured the expression levels of Ddr1 and 2 in renal tissue of AS mice by qRT-PCR. The expression of Ddr1 had no significant difference between wild-type and AS mice. On the other hand, the expression of Ddr2 increased in AS mice in a time-dependent manner. This suggests the possibility that DDR2 is related to renal pathology. Therefore, I knocked down Ddr2 using antisense oligonucleotides (ASO) in 16- to 24-week-old AS mice (DDR2-ASO: 5, 15 mg/kg/week s.c.). I measured renal function parameters and performed renal histological analysis. The administration of DDR2-ASO reduced Ddr2 gene expression in renal tissue to the same level as wild-type mice at both doses of 5 and 15 mg/kg ASO. However, in any of the doses, improvements in various renal function parameters (proteinuria, serum creatinine, blood urea nitrogen) were not observed. Similarly, the expression of renal failure markers (Lysozyme, Lcn2), and inflammatory cytokines (Il-1β, Il-6, Il-8) in renal tissues were also not improved by administration of DDR2 ASO. Intriguingly, the administration of DDR2-ASO has inhibitory effect on the expression of some fibrosis-related genes (α-Sma, Col1a1). However, Masson-trichrome staining of renal tissue revealed no significant improvement of fibrosis. In conclusion, we found that although knockdown of CKD-induced Ddr2 expression reduced the fibrosis-related factors, it does not ameliorate renal fibrosis in AS mouse model. Further studies are needed to elucidate the mechanism of renal fibrogenesis and the role of DDRs in this process to find effective therapy for CKD.