Study On The Role Of ABRO1 In Sepsis By Conditional Knockout Mice

ABRO1(Abraxas Brother 1)is a multifunctional protein that participates in DNA damage and repair,oxidative stress,and inflammation et al;however,it’s role in bacterial infection-induced sepsis is still unclear.Previous studies in our lab showed that ABRO1-deficient mice protected from polymicrobial sepsis induced by cecal ligation and puncture(CLP),as accessed by elevated survival rate,attenuated multiple tissue damage,decreased bacterial load,and reduced systematic inflammatory storm.To further reveal the key effctor cells responsible for the protective effect of ABROl deficiency in CLP-induced sepsis,we constructed Abro1fox/flox mice using CRISPR/Cas9 technology.To generate myeloid-specific(MKO)or neutrophil-specific(NKO)ABRO1 knockout mice,Abro1flox/flox mice were crossed with lyz2-Cre mice or MRP8-Cre mice,respectively.We found that ABRO1 MKO mice displayed attenuated multiple tissue damage,decreased bacterial load,and reduced serum levels of pro inflammatory cytokines compared to wild tipe(WT)mice in sepsis induced by CLP.Similarly,neutrophil-specific knockout of ABRO1 significantly attenuated tissue damage,decreased bacterial load,and reduced serum pro inflammatory cytokines in CLP-induced septic mice.Notebly,both MKO and NKO mice showed a remarkably increased number of neutrophils in the peritoneal cavity compared to their control littermates after CLP-induced sepsis.The results previously obtained in our lab demonstrated that ABRO1-knockout mice with depletion of neutrophls loss the ability to protect against CLP-induced sepsis.Therefore,ablation of ABRO1 prevents sepsis depending on nethrophils.Mechanistically,previous studies in our lab found that lack of ABRO1 selectively promoted CXCR2 mediated neutrophil chemotaxis.To further reveal by which mechanism ABRO1 regulates CXCR2 receptor activation,we generated HEK-293 cells with stable overexpression of CXCR2.Besides,we demonstrated that ABRO1 can not bind to CXCR2 and dose not affect the ubiquitination of CXCR2.Taken together,this study confirmed that neutrophils are the key effector cells responsible for the protective effect of ABRO1 deficiency in CLPinduced sepsis,whichprovides a solid surport for further investigation of the underlying cellular and molecular mechanisms.