Macrophage Regnase-1 Deletion Deteriorates Liver Ischemia/Reperfusion Injury Through Regulation of Macrophage Polarization

Abstract

Background: Regnase-1 (MCPIP) has been identified as an anti-inflammatory agent, but little is known about its influence on liver ischemia/reperfusion (I/R) injury. Macrophages can evolve biphasic responses and differentiate into remarkable polarizations, contributing greatly to the uncontrolled inflammatory cascades during liver I/R injury. Therefore, the aim of this study was to explore whether regnase-1 participated in liver I/R via manipulating macrophage polarization.Materials and methods: C57BL/6 mice were randomly divided into five groups: Sham, I/R, Clodronate, Clo + BMDM, and Clo + LV MCPIP BMDM. A liver I/R model was established, and histopathological and immunostaining examinations were performed for the liver specimens; double immunofluorescence staining was used to localize MCPIP in the liver. Primary hepatocytes were isolated to simulate a hypoxia and reoxygenation (H/R) model in vitro. Bone marrow-derived macrophages (BMDM) were extracted and subjected to lentiviral transduction to knockdown MCPIP expression. BMDM with or without MCPIP deletion were exposed to H/R supernatants, and the polarized states were measured by flow cytometry. RT-PCR analysis and Western blot were also conducted.Results: Compared to those in the Sham group, liver functions and Suzuki's scores were deteriorated in the I/R group, which were reversed in the Clodronate group. The increased expression of regnase-1 in the I/R group diminished with pretreatment of clodronate liposomes. Subsequent double immunofluorescence staining established the localization of regnase-1 in macrophages in the liver. The insulted lesions in the Clodronate group became progressively aggravated with adoptive transfer of BMDM in the Clo + BMDM group, and they were further exacerbated with the transfusion of BMDM with MCPIP knockdown in the Clo + LV MCPIP BMDM group. Gene expressions of M1 and M2 markers were detected by RT-PCR, suggesting that MCPIP knockdown tended to favor the M1 transformation. Subsequently, ex vivo flow cytometrical detection

Macrophage-Specific MCPIP1/Regnase-1 Attenuates Kidney Ischemia-Reperfusion Injury by Shaping the Local Inflammatory Response and Tissue Regeneration

“…MCPIP1 is important for tissue regeneration because LysM-specific knockout mice presented with loss of tubular epithelial cells and renal fibrosis upon kidney IRI compared to wild-type mice. This is in line with previous studies showing that Mcpip1 knockdown aggravates liver IRI in mice [35]. Thus, MCPIP1 acts as a negative regulator of immune responses in the kidney [41,42,[51][52][53]].…”

“…Recent reports have indicated that MCPIP1 is involved in ischemic injury [35]. In this study, we used primary renal parenchymal cells, macrophages, and J774 macrophages to investigate the effects of exposure to reduced oxygen levels.…”

Role of Mcpip1 in obesity‐induced hepatic steatosis as determined by myeloid and liver‐specific conditional knockouts

“…It had already been shown that proinflammatory M1 macrophages infiltrating BAT impair its ability to appropriately respond to thermogenic stimuli, by the secretion of TNFα and IL‐1β that suppress the induction of Ucp1 gene expression [48,49]. Since Mcpip1 inhibits the classic activation of M1 macrophages and promotes M2 polarization, we postulate that the hypothermia of Mcpip1 fl/fl LysM Cre mice might be at least partially explained by an increased infiltration of M1 macrophages into BAT and a high level of Tnfa [29,50].…”

“…Additionally, Mcpip1 regulates the outcome of liver I/ R through modifying macrophage polarization. Mcpip1 knockdown shifted the balance of M1/M2 status toward M1 via the sensitization of the NF-jB p65 pathway leading to deteriorated disease [29].…”

“…Mcpip1 knockdown shifted the balance of M1/M2 status toward M1 via the sensitization of the NF-jB p65 pathway leading to deteriorated disease [29].…”