Objectives T‐cell immunoglobulin domain and mucin domain‐4 (TIM‐4) is selectively expressed on antigen‐presenting cells (APCs) and modulates various immune responses. However, the role of TIM‐4 expressed by Kupffer cells (KCs) in liver fibrosis remains unclear. The present study aimed to explore whether and how TIM‐4 expressed by KCs is involved in liver fibrosis. Materials and Methods Mice chronic liver fibrosis models were established and divided into the olive‐induced control group, CCL4‐induced control group, olive‐induced TIM‐4 interference group and CCL4‐induced TIM‐4 interference group. Different techniques were used to monitor the fibrotic effects of TIM‐4, including histopathological assays, Western blotting, ELISA and transmission electron microscopy. Additionally, mice liver transplant models were established to determine the fibrotic effects of TIM‐4 on fibrosis after liver transplantation (LT). Results We found that the induction of liver fibrosis by CCL4 was associated with TIM‐4 expression in KCs. TIM‐4 interference essentially contributed to liver fibrosis resolution. KCs from the TIM‐4 interference group had decreased levels of pro‐fibrotic markers, reduced TGF‐β1 secretion and inhibited hepatic stellate cell (HSC) differentiation into myofibroblast‐like cells. In addition, we used GdCl3 to verify that KCs are the primary source of TGF‐β1 during fibrosis progression. Moreover, KCs from CCL4‐induced mice showed increased ROS production, mitophagy activation and TGF‐β1 secretion. However, TIM‐4 interference in the KCs inhibited Akt1‐mediated ROS production, resulting in the suppression of PINK1, Parkin and LC3‐II/I activation and the reduction of TGF‐β1 secretion during liver fibrosis. Additionally, TIM‐4 interference potentially attenuated development of fibrosis after LT. Conclusions Our findings revealed the underlying mechanisms of TIM‐4 interference in KCs to mitigate liver fibrosis.
To investigate the effect and mechanism of macrophage membrane-coated nanoparticles (M-NPs) on hepatic ischemia-reperfusion injury (I/RI) caused by orthotopic liver transplantation. In addition, the advantages of TLR4 + /M-NPs compared to M-NPs are discussed. Materials and Methods: We prepared biomimetic M-NPs and identified their characteristics. M-NPs were injected into an SD rat model of orthotopic liver transplantation, and the anti-inflammatory and anti-I/RI activities of M-NPs were studied in vivo and in vitro. In addition, we overexpressed macrophage membrane Toll-like receptor 4 (TLR4) in vitro and prepared TLR4+/M-NPs. Then, we assessed the characteristics and advantages of TLR4 +/M-NPs. Results: The M-NPs neutralized endotoxin, inhibited the overactivation of Kupffer cells (KCs) and suppressed the secretion of inflammatory factors by inhibiting the endotoxinmediated TLR4/MyD88/IRAK1/NF-κB signaling pathway. In an orthotopic liver transplantation model in SD rats, M-NPs showed significant therapeutic efficacy by neutralizing endotoxin and suppressing the secretion of inflammatory factors. Moreover, overexpression of TLR4 on the macrophage membrane by using a TLR4 +-plasmid in vitro effectively reduced the amount of M-NPs needed to neutralize an equivalent dose of endotoxin, reducing the potential risks of NP overuse. Conclusion: This study indicates that M-NPs can effectively alleviate I/RI induced by liver transplantation.
Multiple mechanisms are involved in regulating hepatic ischemia-reperfusion injury (IRI), in which Kupffer cells (Kcs), which are liver-resident macrophages, play critical roles by regulating inflammation and the immune response. Suberoylanilide hydroxamic acid (SAHA), a pan-histone deacetylase inhibitor, has anti-inflammatory effects and induces autophagy. To investigate whether SAHA ameliorates IRI and the mechanisms by which SAHA exerts its effects, an orthotopic liver transplantation (OLT) rat model was established after treatment with SAHA. The results showed that SAHA effectively ameliorated OLT-induced IRI by reducing M1 polarization of Kcs through inhibition of the AKT/glycogen synthase kinase (GSK)3β/NF-κB signaling pathway. Furthermore, the present study found that SAHA upregulates autophagy 5 protein (ATG5)/Lc3B in Kcs through the AKT/mTOR signaling pathway and inhibition of autophagy by knockdown of ATG5 in Kcs partly impaired the protective effect of SAHA on IR-injured liver. Therefore, the current study demonstrated that SAHA reduces M1 polarization of Kcs by inhibiting the AKT/GSK3β/NF-κB pathway and upregulates autophagy in Kcs through the AKT/mTOR signaling pathway, which both alleviate OLT-induced IRI. The present study revealed that SAHA may be a novel treatment for the amelioration of OLT-induced IRI.
Background. Liver ischaemia-reperfusion injury (IRI) remains a problem in liver transplantation. Interleukin-4 (IL-4) has been found to reduce liver IRI, but the exact mechanism remains unclear. Methods. Donor livers were infused with recombinant IL-4 or normal saline during cold storage, and the hepatocellular apoptosis and the inflammatory response were detected. The effect of IL-4 treatment on Kupffer cells (KCs) polarization and expression of the STAT6-JMJD3 pathway was evaluated in vivo and in vitro. KCs in donor livers were depleted by clodronate liposome treatment or JMJD3 was inhibited by GSK-J4 before liver transplantation to determine whether the protective effect of IL-4 treatment was dependent on KCs. Results. IL-4 treatment decreased sALT and sAST levels and alleviated hepatocellular apoptosis and inflammation at 6 h after liver transplantation. IL-4 treatment induced KCs alternatively activated (M2) polarization in vitro and in vivo, and the expression of STAT6 and JMJD3 was increased. JMJD3 knockdown abolished KCs M2 polarization and reduced the antiapoptotic and anti-inflammatory effects induced by IL-4 treatment in vitro. In addition, the protection of IL-4 treatment against IRI induced by liver transplantation was significantly reduced after the depletion of KCs or the inhibition of JMJD3 in donor livers. Conclusions. IL-4 treatment-induced KCs M2 polarization was dependent on the STAT6-JMJD3 pathway and protected liver grafts from IRI after liver transplantation.
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