IL-22 relieves sepsis-induced liver injury via activating JAK/STAT3 signaling pathway

ACE2 Expressed on Myeloid Cells Alleviates Sepsis-Induced Acute Liver Injury via the Ang-(1-7)-Mas Receptor Axis

Sepsis-induced acute liver injury (ALI) is common in intensive care units. Angiotensin-converting enzyme 2 (ACE2) plays a vital role in hepatic fibrosis and steatosis; however, its role in sepsis-induced ALI remains unclear. This study found that hepatic ACE2 expression in cecal ligation and puncture (CLP)-treated mice significantly decreased 24 h after CLP. ACE2-transgenic (TG) mice exhibited a significant improvement in CLP-induced ALI, accompanied by the inhibition of hepatocyte apoptosis, oxidative stress, and inflammation, while ACE2-knockout mice demonstrated an opposite trend. During sepsis-induced ALI, ACE2-TG could also elevate the Ang-(1-7) and Mas receptor (MasR) levels in liver tissues. Interestingly, the MasR inhibitor A779 abrogated the favorable effects of ACE2 on CLP-induced ALI. In a bone marrow transplantation experiment, the ACE2-TG transplantation group showed significantly improved inflammation and liver dysfunction, less hepatocyte apoptosis, and reduced oxidative stress after CLP compared with the wild-type transplantation group. In contrast, the ACE2-knockout group showed poor inflammatory response and liver dysfunction, significantly more hepatocyte apoptosis, and elevated oxidative stress than the wild-type transplantation group after CLP. ACE2 protects against sepsis-induced ALI by inhibiting hepatocyte apoptosis, oxidative stress, and inflammation via the Ang-(1-7)-Mas receptor axis. Thus, targeting ACE2 may be a promising novel strategy for preventing and treating sepsis-induced ALI.

Human Beta Defensin 2 Ameliorated Alcohol-Associated Liver Disease in Mice

Alcohol-associated liver disease (ALD) is a prevalent liver disorder and significant global healthcare burden with limited effective therapeutic options. The gut-liver axis is a critical factor contributing to susceptibility to liver injury due to alcohol consumption. In the current study, we tested whether human beta defensin-2 (hBD-2), a small anti-microbial peptide, attenuates experimental chronic ALD. Male C57Bl/6J mice were fed an ethanol (EtOH)-containing diet for 6 weeks with daily administration of hBD-2 (1.2 mg/kg) by oral gavage during the final week. Two independent cohorts of mice with distinct baseline gut microbiota were used. Oral hBD-2 administration attenuated liver injury in both cohorts as determined by decreased plasma ALT activity. Notably, the degree of hBD-2-mediated reduction of EtOH-associated liver steatosis, hepatocellular death, and inflammation was different between cohorts, suggesting microbiota-specific mechanisms underlying the beneficial effects of hBD-2. Indeed, we observed differential mechanisms of hBD-2 between cohorts, which included an induction of hepatic and small intestinal IL-17A and IL-22, as well as an increase in T regulatory cell abundance in the gut and mesenteric lymph nodes. Lastly, hBD-2 modulated the gut microbiota composition in EtOH-fed mice in both cohorts, with significant decreases in multiple genera including Barnesiella, Parabacteroides, Akkermansia, and Alistipes, as well as altered abundance of several bacteria within the family Ruminococcaceae. Collectively, our results demonstrated a protective effect of hBD-2 in experimental ALD associated with immunomodulation and microbiota alteration. These data suggest that while the beneficial effects of hBD-2 on liver injury are uniform, the specific mechanisms of action are associated with baseline microbiota.

CD1d-Dependent iNKT Cells Control DSS-Induced Colitis in a Mouse Model of IFNγ-Mediated Hyperinflammation by Increasing IL22-Secreting ILC3 Cells

We have previously shown that CD1d-restricted iNKT cells suppress dysregulated IFNγ expression and intestinal inflammation in Yeti mice on the C57BL/6 background. Since type 3 innate lymphoid cells (ILC3s) in mesenteric lymph nodes (MLN) protect against intestinal inflammation in a CD1d-associated manner, we investigated whether crosstalk between iNKT cells and MLN ILC3s controls IFNγ-mediated intestinal inflammation in Yeti mice. We found that Yeti mice display increased levels of ILC3s and that iNKT cell deficiency in Yeti/CD1d KO mice decreases levels of IL22-producing ILC3s during DSS-induced colitis. This finding indicates that iNKT cells and ILC3s cooperate to regulate intestinal inflammation in Yeti mice. Yeti iNKT cells displayed a pronounced anti-inflammatory (IL4- or IL9-producing) phenotype during colitis. Their adoptive transfer to iNKT cell-deficient animals induced a significant increase in IL22 production by ILC3s, indicating that crosstalk between iNKT cells and ILC3s plays a critical role in modulating colitis in Yeti mice. Moreover, we showed that the IL9-producing subset of iNKT cells potently enhances IL22-producing ILC3s in vivo. Taken together, our results identify a central role of the iNKT cell-ILC3 axis in ameliorating IFNγ-mediated intestinal inflammation.