Decoy receptor 3 analogous supplement protects steatotic rat liver from ischemia-reperfusion injury

Background: For steatotic livers, pharmacological approaches to minimize the hepatic neutrophil and macrophage infiltration, and cytokine and chemokine release in ischemia-reperfusion (IR) injury are still limited. Tumor necrosis factor (TNF)-α superfamily-stimulated pathogenic cascades and M1 macrophage/Kupffer cells (KC) polarization from Th1 cytokines are important in the pathogenesis of IR liver injury with hepatic steatosis (HS). Conversely, anti-inflammatory M2 macrophages produce Th2 cytokine (interleukin-4), which reciprocally enhances M2 polarization. Toll-like receptor 4-activated KCs can release proinflammatory mediators, skew M1 polarization and escalate liver IR injury. Decoy receptor 3 (DcR₃) could be potential agents simultaneously blocking the IR liver injury-related pathogenic changes and extend the survival of steatotic graft.

Methods: Rats were fed with methionine and choline-deficient high-fat diet (MCD HFD) for 6 weeks to induce HS. Preliminary experiments with HS group and IR group were conducted, and either immunoglobulin G Fc protein or DcR3 analogue was treated for 14 days in all groups to evaluate the severity. In the Zucker rat-focused experiments, various serum and hepatic substances, M1 polarization, and hepatic microcirculation were assessed.

Results: We found that serum/hepatic DcR₃ levels were lower in nonalcoholic fatty liver disease patients with HS. DcR₃a protected Zucker rats with HS from IR liver injury. The beneficial effects of DcR₃a supplement were mediated by inhibiting hepatic M1 polarization of KCs, decreasing serum/hepatic TNFα, nitric oxide, nitrotyrosine, soluble TNF-like cytokine 1A, Fas ligand, and interferon-γ levels, neutrophil infiltration, and improving hepatic microcirculatory failure among rats with IR-injured steatotic livers. Additionally, downregulated hepatic TNF-like cytokine 1A/Fas-ligand and toll-like receptor 4/nuclear factor-κB signals were found to mediate the DcR₃a-related protective effects of steatotic livers from IR injury.

Conclusion: Using multimodal in vivo and in vitro approaches, we found that DcR₃a analogue was a potential agent to protect steatotic liver against IR injury by simultaneous blockade of the multiple IR injury-related pathogenic changes.