Anti-TNF-induced autoimmune hepatitis

Diosmetin alleviates TNFα-induced liver inflammation by improving liver sinusoidal endothelial cell dysfunction

Sterile inflammation contributes to the development of many liver diseases including non-alcoholic fatty liver disease. Tumor necrosis factor alpha (TNFα) is a key cytokine driving liver inflammation primarily through pro-inflammatory activation of liver sinusoidal endothelial cells (LSEC). The knowledge of whether modulating LSEC activation can alleviate liver inflammation is scarce. This study aims to establish and validate an animal model mimicking LSEC dysfunction observed in obese patients with elevated plasma levels of TNFα, and explore whether vasoactive flavonoid diosmetin could serve as a therapeutic agent for liver inflammation by modulation of LSEC dysfunction. Obese patients with elevated plasma levels of TNFα, LSEC dysfunction and liver inflammation had also reduced Mcpip1 expression in peripheral blood mononuclear cells. Mcpip1 is a protein that negatively regulates the levels of pro-inflammatory cytokines. To model this, we generated mice with Mcpip1 knock-out in myeloid cells (Mcpip1fl/flLysMCre), which displayed systemic and liver inflammation like that observed in patients. Diosmetin treatment efficiently reduced TNFα-dependent LSEC activation in vitro and in vivo, and reduced liver inflammation in Mcpip1fl/flLysMCre mice without affecting systemic inflammation. Diosmetin's effects may stem from inhibiting NF-κB pathway in TNFα-activated endothelial cells. Our findings demonstrate that the Mcpip1fl/flLysMCre mouse model is useful for studying new anti-inflammatory therapies for the liver. We show that diosmetin, a vasoactive flavonoid used in the clinic to treat chronic venous insufficiency, also has strong anti-inflammatory properties in the liver. These results indicate that diosmetin has the potential to be further investigated as a supportive therapy for liver inflammation in humans.

Therapeutic modulation of the liver immune microenvironment

Inflammation is a hallmark of progressive liver diseases such as chronic viral or immune-mediated hepatitis, alcohol-associated liver disease, and NAFLD. Preclinical and clinical studies have provided robust evidence that cytokines and related cellular stress sensors in innate and adaptive immunity orchestrate hepatic disease processes. Unresolved inflammation and liver injury result in hepatic scarring, fibrosis, and cirrhosis, which may culminate in HCC. Liver diseases are accompanied by gut dysbiosis and a bloom of pathobionts, fueling hepatic inflammation. Anti-inflammatory strategies are extensively used to treat human immune-mediated conditions beyond the liver, while evidence for immunomodulatory therapies and cell therapy-based strategies in liver diseases is only emerging. The development and establishment of novel immunomodulatory therapies for chronic liver diseases has been dampened by several clinical challenges, such as invasive monitoring of therapeutic efficacy with liver biopsy in clinical trials and risk of DILI in several studies. Such aspects prevented advancements of novel medical therapies for chronic inflammatory liver diseases. New concepts modulating the liver immune environment are studied and eagerly awaited to improve the management of chronic liver diseases in the future.

Harmful Effects and Potential Benefits of Anti-Tumor Necrosis Factor (TNF)-α on the Liver

Anti-tumor necrosis factor (TNF)-α agents represent an effective treatment for chronic inflammatory diseases. However, some concerns about their potentially undesirable effects on liver function have been reported. On the other hand, evidence of their therapeutic effects on certain liver diseases is accumulating. Many data showed the safety of anti-TNF-α in patients with chronic hepatitis B and C and in liver transplanted patients even if a strict follow-up and prophylaxis are recommended in well-defined subgroups. On the other side, anti-TNF-α-induced liver injury is not a rare event. However, it is often reversible after anti-TNF-α withdrawal. Anti-TNF-α agents have been tested in advanced stages of severe alcoholic hepatitis and non-alcoholic fatty liver disease. Limited data on the efficacy of anti-TNF-α in patients with autoimmune hepatitis and primary biliary cholangitis are also available. In this review, we explored the hepatic safety concerns in patients receiving anti-TNF-α agents with and without pre-existent hepatic diseases. In addition, the available evidence on their potential benefits in the treatment of specific hepatic diseases is discussed.

NOD-Like Receptor Protein 3 Inflammasome-Dependent IL-1β Accelerated ConA-Induced Hepatitis

Autoimmune hepatitis (AIH) is a progressive inflammatory disorders of unknown etiology, characterized by immune-mediated destruction of hepatocytes and massive production of cytokines. Interleukin-1β is a pleiotropic proinflammatory cytokine and well known to be critical in a variety of autoimmune diseases. However, the role of interleukin-1β (IL-1β) in AIH is still indistinct. Here, we first investigated the significance of NOD-like receptor protein 3 (NLRP3) inflammasome-dependent IL-1β in the pathogenesis of AIH with a murine model of immune-mediated hepatitis induced by Concanavalin A (ConA). In ConA-treated mice, pathogenic elevated NLRP3, Cleaved caspase-1 and IL-1β levels, as well as an inflammatory cell death known as pyroptosis predominantly occurred in the livers. Strikingly, NLRP3^−/− and caspase-1^−/− mice were broadly protected from hepatitis as determined by decreased histological liver injury, serum aminotransferase (ALT)/aspartate transaminase levels, and pyroptosis. In vivo intervention with recombinant human interleukin-1 receptor antagonist (rhIL-1Ra) strongly suppressed ConA-induced hepatitis by decreasing tumor necrosis factor-alpha (TNF-α) and interleukin-17 (IL-17) secretion, and inflammatory cell infiltration into livers. Additionally, rhIL-1Ra-pretreated mice developed significantly reduced NLRP3 inflammasome activation and reactive oxygen species (ROS) generation. Scavenging of ROS by N-acetyl-cysteine also attenuated NLRP3 inflammasome activation and liver inflammation, indicating that the essential role of ROS in mediating NLRP3 inflammasome activation in ConA-induced hepatitis. In conclusion, our results demonstrated that NLRP3 inflammasome-dependent IL-1β production was crucial in the pathogenesis of ConA-induced hepatitis, which shed light on the development of promising therapeutic strategies for AIH by blocking NLRP3 inflammasome and IL-1β.

The use of immunosuppression in autoimmune hepatitis: A current literature review

Autoimmune hepatitis (AIH) is an organ specific autoimmune condition which can manifest at any age of life. The heterogeneous nature of this condition means that great variation can be seen in severity, progression of disease and response to treatment within this patient group. Since the 1980s prednisolone and azathioprine have been used for induction and remission of the disease and remain the mainstay of treatment. Other immunosuppressive agents have been employed in difficult to treat cases. While there is less published data regarding these agents compared with the conventional treatments of steroid and azathioprine, there is mounting evidence to support the use of mycophenolate mofetil as a second-line agent. The calcineurin inhibitors, though less studied, additionally show promise. More data is needed on the use of biological agents in refractory disease. This review focuses on our centre’s approach to treatment of AIH in the context of a contemporary review of the literature.

Autoimmune hepatitis, one disease with many faces: Etiopathogenetic, clinico-laboratory and histological characteristics

Autoimmune hepatitis (AIH) is an unresolving progressive liver disease of unknown etiology characterized by hypergammaglobulinemia, autoantibodies detection and interface hepatitis. Due to the absence of specific diagnostic markers and the large heterogeneity of its clinical, laboratory and histological features, AIH diagnosis may be potentially difficult. Therefore, in this in-depth review we summarize the substantial progress on etiopathogenesis, clinical, serological and histological phenotypes of AIH. AIH has a global distribution affecting any age, both sexes and all ethnic groups. Clinical manifestations vary from asymptomatic to severe or rarely fulminant hepatitis. Hypergammaglobulinemia with selective elevation of IgG is found in most cases. Autoimmune attack is perpetuated, possibly via molecular mimicry, and favored by the impaired control of T-regulatory cells. Histology (interface hepatitis, emperipolesis and hepatic rosette formation) and autoantibodies detection although not pathognomonic, are still the hallmark for a timely diagnosis. AIH remains a major diagnostic challenge. AIH should be considered in every case in the absence of viral, metabolic, genetic and toxic etiology of chronic or acute hepatitis. Laboratory personnel, hepato-pathologists and clinicians need to become more familiar with disease expressions and the interpretation of liver histology and autoimmune serology to derive maximum benefit for the patient.