Preliminary Study On The Expression And Significance Of Gremlin In Liver Tissue Of Infants With Biliary Atresia

Objective: In this study,the expression of Gremlin(endogenous antagonist of bone morphogenetic protein,BMP),in the liver tissue of infants with biliary atresia(BA)was detected to understand the relationship between Gremlin and hepatic fibrosis in infants with biliary atresia,and to explore the relevant mechanism.Methods: Intraoperative liver tissue samples were collected from children hospitalized in Shenzhen Children’s Hospital from March 2019 to September 2019,including: biliary atresia(BA)group: liver tissue samples 15 cases(male/female 7/8)with an age range of1 month to 3 months(Average age: 63.95±27.43 days)and choledochal cyst(CC)group(control group): liver tissue samples 15 cases(male/female 4/11)with an age range of 1months to 1 years and 2 months(Average age: 321.60±125.38 days).The expression of Gremlin in BA group and control group was detected by Quantitative real-time PCR(q RT-PCR)and Western blotting(WB);the expression of Smad1 protein in canonical pathway was detected by Western blotting.SPSS24.0、Graphpad Prism 8.0 and Image J image analysis software were used to analyze on the expressions of Gremlin and Smad1,to clarify the differences in the transcription level and protein expression level of Gremlin in the two groups,and to explore the mechanism of Gremlin in the process of BA liver fibrosis.Results:(1)The results of q RT-PCR indicated that: Gremlin1 m RNA in liver tissue of children with choledochal cyst was about 9.8 times higher than that of children with biliary atresia(P<0.01),that is,compared with the control group(choledochal cyst,CC),the expression of Gremlin 1 in biliary atresia samples was significantly down-regulated at the transcriptional level(P<0.01).(2)Gremlin 1 and gremlin 2 protein expression levels in the samples were determined by Western blot,with GAPDH as an internal reference protein.The results showed that gremlin 1 expression was significantly downregulated at the protein level(P<0.05)in BA samples compared to controls,which was consistent with the quantitative real-time PCR results.The expression of gremlin 2was also significantly downregulated in BA samples(P<0.05).(3)The results showed that the expression of Smad1 was down-regulated in BA,but the phosphorylation level remained unchanged(the phosphorylation proportion increased),suggesting that Gremlin may participate in the liver fibrosis process of BA through BMP/Smad pathway Conclusion: In liver tissue of infants with biliary atresia,Gremlin1 and Gremlin2 present a low expression level,suggesting that Gremlin may be involved in the process of BA liver fibrosis;in addition,the proportion of Smad1 phosphorylation in BMP pathway is increased,suggesting that Gremlin may play a protective role in the process of biliary atresia liver fibrosis through the BMP/Smad pathway.