Su SB, Qin SY, Xian XL, Huang FF, Huang QL, ZhangDi HJ, Jiang HX. Interleukin-22 regulating Kupffer cell polarization through STAT3/Erk/Akt crosstalk pathways to extenuate liver fibrosis.
Life Sci 2021;
264:118677. [PMID:
33129875 DOI:
10.1016/j.lfs.2020.118677]
[Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/14/2020] [Accepted: 10/24/2020] [Indexed: 12/19/2022]
Abstract
AIMS
Interleukin (IL)-22 activates multiple signaling pathways to exert anti-inflammatory effects, but few studies have examined whether and how IL-22 may shift macrophage polarization between M1 (pro-inflammatory) and M2 (anti-inflammatory) states and thereby influence the progression of hepatic fibrosis.
MAIN METHODS
Utilized CCl4 to induce liver fibrosis in mice, detected the role of IL-22 in inhibiting liver fibrosis by regulating Kupffer cells (KCs) polarization in vivo and in vitro. U937 cells were used to confirm the mechanism of IL-22 regulating macrophage polarization via the STAT3/Erk/Akt pathways. Human liver specimens were collected to verify the correlation between the levels of IL-22 and KCs during liver fibrogenesis.
KEY FINDINGS
During CCl4-induced liver fibrosis progression in mice, adding exogenous IL-22 significantly inhibited pro-fibrogenic and macrophage phenotype-altering factors secreted by M1-KCs, and it increased the number of M2-KCs. In co-cultures of hepatic stellate cells and KCs from mice treated with IL-22, a high M2/M1-KCs ratio inhibited collagen production and stellate cell activation. These results suggest that IL-22 can increase the ratio of M2-KCs to M1-KCs and thereby attenuate the progression of liver fibrosis. Mechanistic studies in vitro showed that IL-22 promoted polarization of lipopolysaccharide-treated U937 macrophages from M1 to M2. The cytokine exerted these effects by activating the STAT3 pathway while suppressing Erk1/2 and Akt pathways. Furthermore, immunofluorescent staining in human liver specimens confirmed that IL-22 levels positively correlated with the number of M2-KCs during liver fibrogenesis.
SIGNIFICANCE
IL-22 regulates the STAT3/Erk/Akt to increase the M2/M1-KCs ratio and thereby slow liver fibrogenesis.
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