IL-30 (IL27p28) attenuates liver fibrosis through inducing NKG2D-rae1 interaction between NKT and activated hepatic stellate cells in mice

IL-30 protects against sepsis-induced myocardial dysfunction by inhibiting pro-inflammatory macrophage polarization and pyroptosis

Cardiac dysfunction is a well-recognized complication of sepsis and seriously affects the prognosis of sepsis patients. IL-30 has been reported to exert anti-inflammatory effects in various diseases. However, the role of IL-30 in sepsis-induced myocardial dysfunction (SIMD) remains unclear. Here, we explored the protective role of IL-30 in cecum ligation and puncture (CLP)-induced SIMD mice. IL-30 expression increased in the cardiac tissues of septic mice and was mainly derived from macrophages. IL-30 deletion or neutralization aggravated sepsis-induced cardiac dysfunction and injury, whereas recombinant IL-30 treatment significantly ameliorated it. Mechanistically, IL-30 deficiency exerts pro-inflammatory effects by promoting Ly6Chigh macrophage polarization and pyroptosis. Inhibiting NLRP3 with MCC950 significantly reversed cardiac dysfunction, macrophage polarization and pyroptosis aggravated by IL-30 deficiency. Recombinant IL-30 inhibited pro-inflammatory macrophage polarization and pyroptosis in vivo and vitro. Taken together, these results suggest that IL-30 protects against SIMD by inhibiting pro-inflammatory macrophage polarization and pyroptosis.

The Important Roles of Natural Killer Cells in Liver Fibrosis

Liver fibrosis accompanies the development of various chronic liver diseases and promotes their progression. It is characterized by the abnormal accumulation of extracellular matrix proteins (ECM) and impaired ECM degradation. Activated hepatic stellate cells (HSCs) are the major cellular source of ECM-producing myofibroblasts. If liver fibrosis is uncontrolled, it may lead to cirrhosis and even liver cancer, primarily hepatocellular carcinoma (HCC). Natural killer (NK) cells are a key component of innate immunity and have miscellaneous roles in liver health and disease. Accumulating evidence shows that NK cells play dual roles in the development and progression of liver fibrosis, including profibrotic and anti-fibrotic functions. Regulating NK cells can suppress the activation of HSCs and improve their cytotoxicity against activated HSCs or myofibroblasts to reverse liver fibrosis. Cells such as regulatory T cells (Tregs) and molecules such as prostaglandin E receptor 3 (EP₃) can regulate the cytotoxic function of NK cells. In addition, treatments such as alcohol dehydrogenase 3 (ADH3) inhibitors, microRNAs, natural killer group 2, member D (NKG2D) activators, and natural products can enhance NK cell function to inhibit liver fibrosis. In this review, we summarized the cellular and molecular factors that affect the interaction of NK cells with HSCs, as well as the treatments that regulate NK cell function against liver fibrosis. Despite a lot of information about NK cells and their interaction with HSCs, our current knowledge is still insufficient to explain the complex crosstalk between these cells and hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, B cells, and T cells, as well as thrombocytes, regarding the development and progression of liver fibrosis.

Insights on drug and gene delivery systems in liver fibrosis

Complications of the liver are amongst the world's worst diseases. Liver fibrosis is the first stage of liver problems, while cirrhosis is the last stage, which can lead to death. The creation of effective anti-fibrotic drug delivery methods appears critical due to the liver's metabolic capacity for drugs and the presence of insurmountable physiological impediments in the way of targeting. Recent breakthroughs in anti-fibrotic agents have substantially assisted in fibrosis; nevertheless, the working mechanism of anti-fibrotic medications is not fully understood, and there is a need to design delivery systems that are well-understood and can aid in cirrhosis. Nanotechnology-based delivery systems are regarded to be effective but they have not been adequately researched for liver delivery. As a result, the capability of nanoparticles in hepatic delivery was explored. Another approach is targeted drug delivery, which can considerably improve efficacy if delivery systems are designed to target hepatic stellate cells (HSCs). We have addressed numerous delivery strategies that target HSCs, which can eventually aid in fibrosis. Recently genetics have proved to be useful, and methods for delivering genetic material to the target place have also been investigated where different techniques are depicted. To summarize, this review paper sheds light on the most recent breakthroughs in drug and gene-based nano and targeted delivery systems that have lately shown useful for the treatment of liver fibrosis and cirrhosis.

IL-27 suppresses spring viremia of carp virus replication in zebrafish

Interleukin (IL) 27 is a member of the IL-12 family and is a heterodimeric cytokine composed of IL-27A and Epstein-Barr virus-induced 3 (EBI3). It plays an important role in regulating inflammation and cancer progression. IL-27A not only functions by dimerizing with EBI3 but also acts alone. Here, we report that IL-27A and EBI3 suppress spring viremia of carp virus (SVCV) replication in zebrafish. Expression analysis reveals that il-27a and ebi3 were significantly upregulated in the ZF4 cells by SVCV and poly(I:C), and in the zebrafish caudal fin (ZFIN) cells overexpressed with SVCV genes. Interestingly, il-27a and ebi3 were not modulated by IFNφ1, indicating that they are not IFN stimulated genes (ISGs). Furthermore, overexpression of IL-27A and EBI3 alone inhibited SVCV replication in the EPC cells, but less potent than co-expression of IL-27A and EBI3. Intriguingly, IL-27A could not induce the expression of irf3, ifn, isg15 and mx1. Taken together, our results demonstrate that IL-27A and EBI3 activate innate antiviral response in an IFN independent manner in zebrafish.

The role of hepatic microenvironment in hepatic fibrosis development

AIM

Fibrosis is a common pathological feature of most types of chronic liver injuries. There is no specific treatment for liver fibrosis at present. The liver microenvironment, which fosters the survival and activity of liver cells, plays an important role in maintaining the normal structure and physiological function of the liver. The aim of this review is to deeply understand the role of the liver microenvironment in the dynamic and complicated development of liver fibrosis.

METHODS

After searching in Elsevier ScienceDirect, PubMed and Web of Science databases using 'liver fibrosis' and 'microenvironment' as keywords, studies related to microenvironment in liver fibrosis was compiled and examined.

RESULTS

The homeostasis of the liver microenvironment is disrupted during the development of liver fibrosis, affecting liver cell function, causing various types of cell reactions, and changing the cell-cell and cell-matrix interactions, eventually affecting fibrosis formation.

CONCLUSION

Liver microenvironment may be important for identifying potential therapeutic targets, and restoring microenvironment homeostasis may be an important strategy for promoting the reversal of liver fibrosis.KEY MESSAGESThe homeostasis of the liver microenvironment is disrupted in liver fibrosis;A pro-fibrotic microenvironment is formed during the development of liver fibrosis;Restoring microenvironment homeostasis may be an important strategy for promoting the reversal of liver fibrosis.

Pathology and molecular mechanisms of Schistosoma japonicum-associated liver fibrosis

Schistosomiasis has been widely disseminated around the world, and poses a significant threat to human health. Schistosoma eggs and soluble egg antigen (SEA) mediated inflammatory responses promote the formation of egg granulomas and liver fibrosis. With continuous liver injuries and inflammatory stimulation, liver fibrosis can develop into liver cirrhosis and liver cancer. Therefore, anti-fibrotic therapy is crucial to increase the survival rate of patients. However, current research on antifibrotic treatments for schistosomiasis requires further exploration. In the complicated microenvironment of schistosome infections, it is important to understand the mechanism and pathology of schistosomiasis-associated liver fibrosis(SSLF). In this review, we discuss the role of SEA in inhibiting liver fibrosis, describe its mechanism, and comprehensively explore the role of host-derived and schistosome-derived microRNAs (miRNAs) in SSLF. Inflammasomes and cytokines are significant factors in promoting SSLF, and we discuss the mechanisms of some critical inflammatory signals and pro-fibrotic cytokines. Natural killer(NK) cells and Natural killer T(NKT) cells can inhibit SSLF but are rarely described, therefore, we highlight their significance. This summarizes and provides insights into the mechanisms of key molecules involved in SSLF development.

New insights into iNKT cells and their roles in liver diseases

Natural killer T cells (NKTs) are an important part of the immune system. Since their discovery in the 1990s, researchers have gained deeper insights into the physiology and functions of these cells in many liver diseases. NKT cells are divided into two subsets, type I and type II. Type I NKT cells are also named iNKT cells as they express a semi-invariant T cell-receptor (TCR) α chain. As part of the innate immune system, hepatic iNKT cells interact with hepatocytes, macrophages (Kupffer cells), T cells, and dendritic cells through direct cell-to-cell contact and cytokine secretion, bridging the innate and adaptive immune systems. A better understanding of hepatic iNKT cells is necessary for finding new methods of treating liver disease including autoimmune liver diseases, alcoholic liver diseases (ALDs), non-alcoholic fatty liver diseases (NAFLDs), and liver tumors. Here we summarize how iNKT cells are activated, how they interact with other cells, and how they function in the presence of liver disease.

Oxidative stress-mediated mitochondrial fission promotes hepatic stellate cell activation via stimulating oxidative phosphorylation

Previous studies have demonstrated dysregulated mitochondrial dynamics in fibrotic livers and hepatocytes. Little is currently known about how mitochondrial dynamics are involved, nor is it clear how mitochondrial dynamics participate in hepatic stellate cell (HSC) activation. In the present study, we investigated the role of mitochondrial dynamics in HSC activation and the underlying mechanisms. We verified that mitochondrial fission was enhanced in human and mouse fibrotic livers and active HSCs. Moreover, increased mitochondrial fission driven by fis1 overexpression could promote HSC activation. Inhibiting mitochondrial fission using mitochondrial fission inhibitor-1 (Mdivi-1) could inhibit activation and induce apoptosis of active HSCs, indicating that increased mitochondrial fission is essential for HSC activation. Mdivi-1 treatment also induced apoptosis in active HSCs in vivo and thus ameliorated CCl₄-induced liver fibrosis. We also found that oxidative phosphorylation (OxPhos) was increased in active HSCs, and OxPhos inhibitors inhibited activation and induced apoptosis in active HSCs. Moreover, increasing mitochondrial fission upregulated OxPhos, while inhibiting mitochondrial fission downregulated OxPhos, suggesting that mitochondrial fission stimulates OxPhos during HSC activation. Next, we found that inhibition of oxidative stress using mitoquinone mesylate (mitoQ) and Tempol inhibited mitochondrial fission and OxPhos and induced apoptosis in active HSCs, suggesting that oxidative stress contributes to excessive mitochondrial fission during HSC activation. In conclusion, our study revealed that oxidative stress contributes to enhanced mitochondrial fission, which triggers OxPhos during HSC activation. Importantly, inhibiting mitochondrial fission has huge prospects for alleviating liver fibrosis by eliminating active HSCs.

MULT1-Encoding DNA Alleviates Schistosomiasis-Associated Hepatic Fibrosis via Modulating Cellular Immune Response

Purpose

In schistosomiasis-associated hepatic fibrosis, the role of murine UL16-binding protein-like transcript 1 (MULT1), the strongest ligand of natural killer group 2-member D receptor (NKG2D), remains unclear. Here, Schistosoma japonicum-infected mice administered with MULT1-encoding DNA were used to test MULT1 as a potential therapy for schistosomiasis-associated hepatic fibrosis and explore relevant mechanisms.

Materials and Methods

A recombinant plasmid encoding MULT1 (p-rMULT1) was constructed and administered to Schistosoma japonicum-infected BALB/c mice via hydrodynamic tail vein injection. Egg granulomas in liver, hepatic fibrosis biomarkers and levels of cytokines were investigated. Comparisons of CD4+ T, CD8+ T, NK and NKT proportions as well as their phenotype were performed not only between Schistosoma infected, p-rMULT1 treated group and Schistosoma infected, backbone plasmid pEGFP-N1 treated group but also between infected, nontreated group and health control group.

Results

Reduced area of granuloma formation and fibrosis around single eggs, downregulated expression of collagen I, α-smooth muscle actin, TGF-β and IL-10, and upregulated expression of IFN-γ, were observed in the livers of p-rMULT1 treated mice. p-rMULT1 treatment improved Schistosoma infection impacted immune microenvironment by modulating proportion of CD4⁺ T CD8⁺ T, natural killer (NK) and NKT cells, enhancing expression of NKG2D, in lymphocytes, and augmenting IFN-γ secretion by CD4⁺ T, CD8⁺ T, NK and NKT cells, as well as partially reversing some other phenotype changes of lymphocytes.

Conclusion

To the best of our knowledge, we provided the first in vivo evidence that MULT1 is a favorable anti-fibrosis factor in the context of schistosomiasis. The inhibitory effect of MULT1 overexpression on schistosomiasis associated with hepatic fibrosis may result from augmenting the proportion and function of NKG2D-expressing immune cells, and from enhancing NK- and T-cell activation, as well as regulating the helper T (Th)1/Th2 balance.

Biogenesis and engineering of interleukin 12 family cytokines

Interleukin 12 (IL-12) family cytokines are secreted proteins that regulate immune responses. Each family member is a heterodimer and nature uses shared building blocks to assemble the functionally distinct IL-12 cytokines. In recent years we have gained insights into the molecular principles and cellular regulation of IL-12 family biogenesis. For each of the family members, generally one subunit depends on its partner to acquire its native structure and be secreted from immune cells. If unpaired, molecular chaperones retain these subunits in cells. This allows cells to regulate and control secretion of the highly potent IL-12 family cytokines. Molecular insights gained into IL-12 family biogenesis, structure, and function now allow us to engineer IL-12 family cytokines to develop novel immunotherapeutic approaches.

Crosstalk Between Autophagy and Innate Immunity: A Pivotal Role in Hepatic Fibrosis

Liver fibrosis is a repair process of chronic liver injuries induced by toxic substances, pathogens, and inflammation, which exhibits a feature such as deposition of the extracellular matrix. The initiation and progression of liver fibrosis heavily relies on excessive activation of hepatic stellate cells (HSCs). The activated HSCs express different kinds of chemokine receptors to further promote matrix remodulation. The long-term progression of liver fibrosis will contribute to dysfunction of the liver and ultimately cause hepatocellular carcinoma. The liver also has abundant innate immune cells, including DCs, NK cells, NKT cells, neutrophils, and Kupffer cells, which conduct complicated functions to activation and expansion of HSCs and liver fibrosis. Autophagy is one specific type of cell death, by which the aberrantly expressed protein and damaged organelles are transferred to lysosomes for further degradation, playing a crucial role in cellular homeostasis. Autophagy is also important to innate immune cells in various aspects. The previous studies have shown that dysfunction of autophagy in hepatic immune cells can result in the initiation and progression of inflammation in the liver, directly or indirectly causing activation of HSCs, which ultimately accelerate liver fibrosis. Given the crosstalk between innate immune cells, autophagy, and fibrosis progression is complicated, and the therapeutic options for liver fibrosis are quite limited, the exploration is essential. Herein, we review the previous studies about the influence of autophagy and innate immunity on liver fibrosis and the molecular mechanism to provide novel insight into the prevention and treatment of liver fibrosis.

EP3 enhances adhesion and cytotoxicity of NK cells toward hepatic stellate cells in a murine liver fibrosis model

Natural killer (NK) cells exhibit antifibrotic properties in liver fibrosis (LF) by suppressing activated hepatic stellate cell (HSC) populations. Prostaglandin E2 (PGE2) plays a dual role in innate and adaptive immunity. Here, we found that E-prostanoid 3 receptor (EP3) was markedly downregulated in NK cells from liver fibrosis mice and patients with liver cirrhosis. NK cell-specific deletion of EP3 aggravated hepatic fibrogenesis in mouse models of LF. Loss of EP3 selectively reduced the cytotoxicity of the CD27+CD11b+ double positive (DP) NK subset against activated HSCs. Mechanistically, deletion of EP3 impaired the adhesion and cytotoxicity of DP NK cells toward HSCs through modulation of Itga4-VCAM1 binding. EP3 upregulated Itga4 expression in NK cells through promoting Spic nuclear translocation via PKC-mediated phosphorylation of Spic at T191. Activation of EP3 by sulprostone alleviated CCL4-induced liver fibrosis in mice. Thus, EP3 is required for adhesion and cytotoxicity of NK cells toward HSCs and may serve as a therapeutic target for the management of LF.

Recent Advancements in Antifibrotic Therapies for Regression of Liver Fibrosis

Cirrhosis is a severe form of liver fibrosis that results in the irreversible replacement of liver tissue with scar tissue in the liver. Environmental toxicity, infections, metabolic causes, or other genetic factors including autoimmune hepatitis can lead to chronic liver injury and can result in inflammation and fibrosis. This activates myofibroblasts to secrete ECM proteins, resulting in the formation of fibrous scars on the liver. Fibrosis regression is possible through the removal of pathophysiological causes as well as the elimination of activated myofibroblasts, resulting in the reabsorption of the scar tissue. To date, a wide range of antifibrotic therapies has been tried and tested, with varying degrees of success. These therapies include the use of growth factors, cytokines, miRNAs, monoclonal antibodies, stem-cell-based approaches, and other approaches that target the ECM. The positive results of preclinical and clinical studies raise the prospect of a viable alternative to liver transplantation in the near future. The present review provides a synopsis of recent antifibrotic treatment modalities for the treatment of liver cirrhosis, as well as a brief summary of clinical trials that have been conducted to date.

Intestinal Fibrosis in Inflammatory Bowel Disease and the Prospects of Mesenchymal Stem Cell Therapy

Intestinal fibrosis is an important complication of inflammatory bowel disease (IBD). In the course of the development of fibrosis, certain parts of the intestine become narrowed, significantly destroying the structure and function of the intestine and affecting the quality of life of patients. Chronic inflammation is an important initiating factor of fibrosis. Unfortunately, the existing anti-inflammatory drugs cannot effectively prevent and alleviate fibrosis, and there is no effective anti-fibrotic drug, which makes surgical treatment the mainstream treatment for intestinal fibrosis and stenosis. Mesenchymal stem cells (MSCs) are capable of tissue regeneration and repair through their self-differentiation, secretion of cytokines, and secretion of extracellular vesicles. MSCs have been shown to play an important therapeutic role in the fibrosis of many organs. However, the role of MSC in intestinal fibrosis largely remained unexplored. This review summarizes the mechanism of intestinal fibrosis, including the role of immune cells, TGF-β, and the gut microbiome and metabolites. Available treatment options for fibrosis, particularly, MSCs are also discussed.

CCl4 inhibits the expressions of hepatic taurine biosynthetic enzymes and taurine synthesis in the progression of mouse liver fibrosis

Carbon tetrachloride (CCl4) is a widely used hepatotoxin for the studies of liver fibrosis and cirrhosis, and taurine has function to abate liver fibrosis induced by CCl4. But the interacting mechanisms between taurine and CCl4 in liver are still largely unknown. These made us to hypothesize that CCl4 may induce liver fibrosis by affecting the expressions of taurine biosynthetic enzymes and taurine synthesis. We thus assayed the expressions of hepatic cysteine dioxygenase (CDO), cysteine sulfonate acid decarboxylase (CSAD) and taurine transporter (TauT) in the progression of mouse liver fibrosis induced by CCl4. The results demonstrated that CCl4 treatment markedly decreased hepatic CSAD, CDO expressions, and taurine levels in hepatic tissue, although TauT expression did not exhibit significant decline. It was contrasting that hepatic α-SMA, serum AST, ALT, ALP kept increasing, which were accompanied by the pathological characters of liver, whereas taurine supplement attenuated the progression of liver fibrosis induced by CCl4. These results demonstrate that CCl4 may induce liver fibrosis by inhibiting hepatic CSAD and CDO expressions and taurine synthesis, which are crucial for our understanding the mechanisms of liver fibrosis induced by CCl4, and also potential for establishing therapeutic strategies of liver fibrosis and related diseases.

Hepatic Stellate Cell-Immune Interactions in NASH

Nonalcoholic fatty liver disease (NAFLD) is the dominant cause of liver disease worldwide. Nonalcoholic steatohepatitis (NASH), a more aggressive presentation of NAFLD, is characterized by severe hepatocellular injury, inflammation, and fibrosis. Chronic inflammation and heightened immune cell activity have emerged as hallmark features of NASH and key drivers of fibrosis through the activation of hepatic stellate cells (HSCs). Recent advances in our understanding of the molecular and cellular pathways in NASH have highlighted extensive crosstalk between HSCs and hepatic immune populations that strongly influences disease activity. Here, we review these findings, emphasizing the roles of HSCs in liver immunity and inflammation, key cell-cell interactions, and exciting areas for future investigation.

NKG2D discriminates diverse ligands through selectively mechano-regulated ligand conformational changes

Stimulatory immune receptor NKG2D binds diverse ligands to elicit differential anti‐tumor and anti‐virus immune responses. Two conflicting degeneracy recognition models based on static crystal structures and in‐solution binding affinities have been considered for almost two decades. Whether and how NKG2D recognizes and discriminates diverse ligands still remain unclear. Using live‐cell‐based single‐molecule biomechanical assay, we characterized the in situ binding kinetics of NKG2D interacting with different ligands in the absence or presence of mechanical force. We found that mechanical force application selectively prolonged NKG2D interaction lifetimes with the ligands MICA and MICB, but not with ULBPs, and that force‐strengthened binding is much more pronounced for MICA than for other ligands. We also integrated steered molecular dynamics simulations and mutagenesis to reveal force‐induced rotational conformational changes of MICA, involving formation of additional hydrogen bonds on its binding interface with NKG2D, impeding MICA dissociation under force. We further provided a kinetic triggering model to reveal that force‐dependent affinity determines NKG2D ligand discrimination and its downstream NK cell activation. Together, our results demonstrate that NKG2D has a discrimination power to recognize different ligands, which depends on selective mechanical force‐induced ligand conformational changes.

IL-30 ameliorates imiquimod and K14-VEGF induced psoriasis-like disease by inhibiting both innate and adaptive immunity disorders

Psoriasis is a severe skin disease with significant physical and psychological health consequences. As a typical type of immune disease, both innate and adaptive immunity disorders play key roles in the development of psoriasis. Interleukin (IL)-30 was thought as a natural antagonist of gp130-mediated signaling that affects T helper type 1 and 17 cell polarization by inhibiting IL-6 and IL-27 signaling pathways. Here, we found that, in vitro, IL-30 reduced cytokine levels of HaCaT keratinocytes and dendritic cells (DCs), weakened the maturationS of DCs, inhibited DC-mediated T cell proliferation, and blocked the activation of nuclear factor-κB. In vivo, IL-30 inhibited the development of skin disease in two animal models: Krt14-Vegfa and imiquimod (IMQ)-induced psoriasis-like skin disease. Thus, IL-30 may be useful as a therapeutic agent for controlling psoriasis.

Cellular and Molecular Mechanisms Underlying Liver Fibrosis Regression

Chronic liver injury of different etiologies may result in hepatic fibrosis, a scar formation process consisting in altered deposition of extracellular matrix. Progression of fibrosis can lead to impaired liver architecture and function, resulting in cirrhosis and organ failure. Although fibrosis was previous thought to be an irreversible process, recent evidence convincingly demonstrated resolution of fibrosis in different organs when the cause of injury is removed. In the liver, due to its high regenerative ability, the extent of fibrosis regression and reversion to normal architecture is higher than in other tissues, even in advanced disease. The mechanisms of liver fibrosis resolution can be recapitulated in the following main points: removal of injurious factors causing chronic hepatic damage, elimination, or inactivation of myofibroblasts (through various cell fates, including apoptosis, senescence, and reprogramming), inactivation of inflammatory response and induction of anti-inflammatory/restorative pathways, and degradation of extracellular matrix. In this review, we will discuss the major cellular and molecular mechanisms underlying the regression of fibrosis/cirrhosis and the potential therapeutic approaches aimed at reversing the fibrogenic process.

Crosstalk between hepatic stellate cells and surrounding cells in hepatic fibrosis

Hepatic fibrosis represents as a dynamic pathological process characterized by the net accumulation of extracellular matrix in the progression of various chronic liver diseases, including viral hepatitis, alcoholic liver disease, and metabolic associated fatty liver disease (MAFLD). Activation of hepatic stellate cells (HSCs) is well-defined to play a central role in the initiation and progression of hepatic fibrosis. However, the activation of HSCs is affected by the complicated microenvironments in liver, which largely attributes to the communication between hepatocytes and multiple tissue-resident cells, including sinusoidal endothelial cells, bile duct epithelial cells, platelets, T cells, B cells, macrophages, natural killer cells, neutrophils, dendritic cells, in the direct or indirect mechanisms. Cellular crosstalk between HSCs and surrounding cells contributes to the activation of HSCs and the progression of hepatic fibrosis. Currently, accumulating evidence have proven the complexity and plasticity of HSCs activation, and further clarification of cellular communication between HSCs and surrounding cells will provide sufficient clue to the development of novel diagnostic methods and therapeutic strategies for hepatic fibrosis.

CD39-mediated ATP-adenosine signalling promotes hepatic stellate cell activation and alcoholic liver disease

CD39 is associated with diverse physiological and pathological processes, including cell proliferation and differentiation. Adenosine triphosphate (ATP) is hydrolysed to adenosine by different enzymes including ecto-nucleoside triphosphate diphosphohydrolase-1/ENTPD1 (CD39) and ecto-5'-nucleotidase (CD73), regulating many physiological and pathological processes in various diseases, but these changes and functions in alcoholic liver disease are generally unknown. In this study, an alcoholic liver disease model in vivo was induced by ethanol plus carbon tetrachloride(CCl4) administered to C57BL/6 mice, who were the intraperitoneally injected with the CD39 inhibitor sodium polyoxotungstate (POM1) or colchicine from the 5th week to the 8th week. Meanwhile, hepatic stellate cells were stimulated by acetaldehyde to replicate alcoholic liver fibrosis models in vitro. Exogenous ATP and POM1 were added in turn to the culture system. Pharmacological blockade of CD39 largely prevents liver damage and collagen deposition. We found that blockade or silencing of CD39 prevented acetaldehyde-induced proliferation of HSC-T6 cells and the expression of fibrogenic factors. Moreover, blockade or silencing of CD39 could block the activation of the adenosine A2A and adenosine A2B receptors and the TGF-β/Smad3 pathway, which are essential events in HSC activation. Thus, blockade of CD39 to inhibit the transduction of ATP to adenosine may prevent HSC activation, alleviating alcoholic hepatic fibrosis. The findings from this study suggest ATP-adenosine signalling is a novel therapeutic and preventive target for alcoholic liver disease.

Role of 5-HT degradation in acute liver injury induced by carbon tetrachloride

5-hydroxytryptamine (5-HT) is involved in the pathological processes of several liver diseases. Acute liver injury underlies the development of many liver diseases, but the mechanism remains unclear. We aimed to investigate the role of 5-HT in carbon tetrachloride (CCl₄)-induced acute liver injury. Acute liver injury was induced with CCl₄ (10 mg/kg) in mice pretreated with the 5-HT_2A receptor antagonist sarpogrelate hydrochloride (SH) and the 5-HT synthesis inhibitor carbidopa (CDP). LO2 cells were treated with CCl₄, 5-HT or 2,5-dimethoxy-4-idopametamine and pretreated with SH, CDP or the monoamine oxidase A (MAO-A) inhibitor clorgyline. Hematoxylin-eosin staining, immunohistochemistry, Real-time quantitative PCR, western blotting, fluorescent probe and biochemical markers were used to evaluate liver compromise. 5-HT_2A receptor, 5-HT synthetase and MAO-A were expressed in hepatocytes; their gene and protein expression were upregulated by CCl₄, which led to the degradation of mitochondrial 5-HT and overproduction of reactive oxygen species (ROS). Hepatic injury may be aggravated by ROS, which induce oxidative stress and the phosphorylation of p38 mitogen-activated protein kinase, Jun N-terminal kinase, extracellular regulated protein kinase, signal transducer and activator of transcription 3 and nuclear factor kappa-B. 5-HT_2A receptor may contribute to acute liver injury by modulating 5-HT synthase and MAO-A expression. The synergistic action of SH and CDP treatment may inhibit CCl₄-induced acute liver injury in a dose-dependent manner. Hence, CCl₄-induced acute liver injury is due to an increase in mitochondrial ROS production caused by increased 5-HT degradation and probably involves increases in 5-HT_2A receptor expression and 5-HT synthesis.

Natural killer T cell/IL-4 signaling promotes bone marrow-derived fibroblast activation and M2 macrophage-to-myofibroblast transition in renal fibrosis

Renal fibrosis is a histological manifestation of chronic kidney disease. Natural killer T (NKT) cells have a critical role in the pathogenesis of fibrotic disorder. However, the role of NKT cells in regulating kidney fibrosis remains largely unknown. In the current study, we showed that the percentages of NKT⁺ cells and NKT⁺-IL-4⁺ cells were notably increased in folic acid (FA) and obstructive nephropathy. CD1d deficiency protected mice from renal fibrosis induced by FA and obstructive injury. Specifically, Loss of CD1d reduced bone marrow-derived myofibroblasts and CD206⁺/α-smooth muscle actin⁺ cells in the kidneys of injured mice. But mice treated with α-galactosylceramide (α-GC, a specific activator of NKT cells) developed more severe fibrosis, accumulated more myeloid myofibroblasts and M2 macrophages-myofibroblasts transition (M2MMT) cells in FA injured kidneys. Furthermore, IL-4 expression was markedly reduced in CD1d deficiency mice but increased in α-GC-treated mice. Administration of IL-4 abrogates the inhibiting effect of CD1d deficiency on renal fibrosis, bone marrow-derived fibroblasts activation, and M2MMT in FA injured kidneys. Conversely, pharmacological inhibition of IL-4 attenuated the development of renal fibrosis, decreased bone marrow-derived myofibroblasts, and suppressed M2MMT. Thus, this study revealed a novel role of NKT cells in the bone marrow-derived fibroblasts activation and M2MMT during renal fibrosis. Targeting NKT cell/IL-4 signaling may be an effective treatment for renal fibrosis.

Immune Cell Modulation of the Extracellular Matrix Contributes to the Pathogenesis of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a five-year survival rate of only 9%. PDAC is characterized by a dense, fibrotic stroma composed of extracellular matrix (ECM) proteins. This desmoplastic stroma is a hallmark of PDAC, representing a significant physical barrier that is immunosuppressive and obstructs penetration of cytotoxic chemotherapy agents into the tumor microenvironment (TME). Additionally, dense ECM promotes hypoxia, making tumor cells refractive to radiation therapy and alters their metabolism, thereby supporting proliferation and survival. In this review, we outline the significant contribution of fibrosis to the pathogenesis of pancreatic cancer, with a focus on the cross talk between immune cells and pancreatic stellate cells that contribute to ECM deposition. We emphasize the cellular mechanisms by which neutrophils and macrophages, specifically, modulate the ECM in favor of PDAC-progression. Furthermore, we investigate how activated stellate cells and ECM influence immune cells and promote immunosuppression in PDAC. Finally, we summarize therapeutic strategies that target the stroma and hinder immune cell promotion of fibrogenesis, which have unfortunately led to mixed results. An enhanced understanding of the complex interactions between the pancreatic tumor ECM and immune cells may uncover novel treatment strategies that are desperately needed for this devastating disease.

NKG2D Enhances Double-Negative T Cell Regulation of B Cells

Numerous studies reported a small subpopulation of TCRαβ+CD4-CD8- (double-negative) T cells that exert regulatory functions in the peripheral lymphocyte population. However, the origin of these double-negative T (DNT) cells is controversial. Some researchers reported that DNT cells originated from the thymus, and others argued that these cells are derived from peripheral immune induction. We report a possible mechanism for the induction of nonregulatory CD4+ T cells to become regulatory double-negative T (iDNT) cells in vitro. We found that immature bone marrow dendritic cells (CD86+MHC-II- DCs), rather than mature DCs (CD86+MHC-II+), induced high levels of iDNT cells. The addition of an anti-MHC-II antibody to the CD86+MHC-II+ DC group significantly increased induction. These iDNT cells promoted B cell apoptosis and inhibited B cell proliferation and plasma cell formation. A subgroup of iDNT cells expressed NKG2D. Compared to NKG2D- iDNT cells, NKG2D+ iDNT cells released more granzyme B to enhance B cell regulation. This enhancement may function via NKG2D ligands expressed on B cells following lipopolysaccharide stimulation. These results demonstrate that MHC-II impedes induction, and iDNT cells may be MHC independent. NKG2D expression on iDNT cells enhanced the regulatory function of these cells. Our findings elucidate one possible mechanism of the induction of peripheral immune tolerance and provide a potential treatment for chronic allograft rejection in the future.

IL-30† (IL-27A): a familiar stranger in immunity, inflammation, and cancer

Over the years, interleukin (IL)-27 has received much attention because of its highly divergent, sometimes even opposing, functions in immunity. IL-30, the p28 subunit that forms IL-27 together with Ebi3 and is also known as IL-27p28 or IL-27A, has been considered a surrogate to represent IL-27. However, it was later discovered that IL-30 can form complexes with other protein subunits, potentially leading to overlapping or discrete functions. Furthermore, there is emerging evidence that IL-30 itself may perform immunomodulatory functions independent of Ebi3 or other binding partners and that IL-30 production is strongly associated with certain cancers in humans. In this review, we will discuss the biology of IL-30 and other IL-30-associated cytokines and their functions in inflammation and cancer.

Studying the ways that interleukin IL-30 regulates immune responses may provide novel insights into tumor development and inflammatory conditions. Interleukins are a diverse family of proteins involved in intercellular communications and immunity, where they can exert divergent and even opposing functions. Booki Min at Northwestern University in Chicago, USA, and co-workers reviewed the current understanding of IL-30 and its links to inflammation and cancer. IL-30 forms the IL-27 complex with the Ebi3 protein and was thought to be a surrogate for IL-27 in terms of activity. However, recent insights suggest that IL-30 may perform discrete immune modulation functions. Elevated IL-30 secretion is linked to prostate and breast cancer development. Extensive research is needed into the formation of IL-30, its associated protein interactions, and the development of a suitable animal model.

Identification of growth differentiation factor 15 as a pro-fibrotic factor in mouse liver fibrosis progression

The aim of this study was elucidate the inhibitory role of growth differentiation factor 15 (GDF15) in liver fibrosis and its possible activation mechanism in hepatic stellate cells (HSCs) of mice. We generated a GDF15-neutralizing antibody that can inhibit TGF-β1-induced activation of the TGF-β/Smad2/3 pathway in LX-2 cells. All the mice in this study were induced by carbon tetrachloride and thioacetamide. In addition, primary HSCs from mice were isolated from fresh livers using Nycodenz density gradient separation. The severity and extent of liver fibrosis were evaluated by Sirius Red and Masson staining. The effect of GDF15 on the activation of the TGF-β pathway was detected using dual-luciferase reporter and Western blotting assays. The expression of GDF15 in cirrhotic liver tissue was higher than that in normal liver tissue. Blocking GDF15 with a neutralizing antibody resulted in a delay in primary hepatic stellate cell activation and remission of liver fibrosis induced by carbon tetrachloride or thioacetamide. Meanwhile, TGF-β pathway activation was partly inhibited by a GDF15-neutralizing antibody in primary HSCs. These results indicated that GDF15 plays an important role in regulating HSC activation and liver fibrosis progression. The inhibition of GDF15 attenuates chemical-inducible liver fibrosis and delays hepatic stellate cell activation, and this effect is probably mainly attributed to its regulatory role in TGF-β signalling.

Characterization of lymphocyte subsets in ascitic fluid and peripheral blood of decompensated cirrhotic patients with chronic hepatitis C and alcoholic liver disease: A pivotal study

Hepatitis C virus and alcoholic liver disease are major causes of chronic liver diseases worldwide. Little is known about differences between chronic hepatitis C and alcoholic liver disease in terms of lymphocytes’ sub-population. Aim of the present study was to compare the sub-populations of lymphocytes in both ascitic compartment and peripheral blood in patients with decompensated liver cirrhosis due to chronic hepatitis C and alcoholic liver disease. Patients with decompensated liver cirrhosis due to hepatitis C virus or alcoholic liver disease evaluated from April 2014 to October 2016 were enrolled. Whole blood and ascitic fluid samples were stained with monoclonal antibodies specific for human TCRɑβ, TCRɣδ, CD3, CD4, CD8, CD19, CCR6, CD16, CD56, CD25, HLA-DR, Vɑ24. Sixteen patients with decompensated liver cirrhosis were recruited (9 with hepatitis C virus and 7 with alcoholic liver disease). In ascitic fluid, the percentage of both CD3⁺CD56⁻ and CD3⁺CD56⁺iNKT cells resulted higher in hepatitis C virus patients than in alcoholic liver disease patients (1.82 ± 0.35% vs 0.70 ± 0.42% (p < 0.001) and 1.42 ± 0.35% vs 0.50 ± 0.30% (p < 0.001), respectively). Conversely, in peripheral blood samples, both CD3⁺CD56⁻ and CD3⁺CD56⁺iNKT cells resulted significantly higher in alcoholic liver disease than in hepatitis C virus patients (4.70 ± 2.69% vs 1.50 ± 1.21% (p < 0.01) and 3.10 ± 1.76% vs 1.00 ± 0.70% (p < 0.01), respectively). Both elevation of iNKT cells in ascitic fluid and reduction in peripheral blood registered in hepatitis C virus but not in alcoholic liver disease patients might be considered indirect signals of tissutal translocation. In conclusion, we described relevant differences between the two groups. Alcoholic liver disease patients displayed lower number of CD3⁺CD4⁺ cells and a higher percentage of CD3⁻CD16⁺, Vα24⁺CD3⁺CD56⁻ and Vα24⁺CD3⁺CD56⁺iNKT cells in ascitic fluid than hepatitis C virus positive subjects. Further studies might analyze the role of immune cells in the vulnerability toward infections and detect potential targets for new treatments especially for alcoholic liver disease patients.

Silencing p53 inhibits interleukin 10-induced activated hepatic stellate cell senescence and fibrotic degradation in vivo

Activated hepatic stellate cells are reported to play a significant role in liver fibrogenesis. Beside the phenotype reversion and apoptosis of activated hepatic stellate cells, the senescence of activated hepatic stellate cells limits liver fibrosis. Our previous researches have demonstrated that interleukin-10 could promote hepatic stellate cells senescence via p53 signaling pathway in vitro. However, the relationship between expression of p53 and senescence of activated hepatic stellate cells induced by interleukin-10 in fibrotic liver is unclear. The purpose of present study was to explore whether p53 plays a crucial role in the senescence of activated hepatic stellate cells and degradation of collagen mediated by interleukin-10. Hepatic fibrosis animal model was induced by carbon tetrachloride through intraperitoneal injection and transfection of interleukin-10 gene to liver was performed by hydrodynamic-based transfer system. Depletions of p53 in vivo and in vitro were carried out by adenovirus-based short hairpin RNA against p53. Regression of fibrosis was assessed by liver biopsy and collagen staining. Cellular senescence in the liver was observed by senescence-associated beta-galactosidase (SA-β-Gal) staining. Immunohistochemistry, immunofluorescence double staining, and Western blot analysis were used to evaluate the senescent cell and senescence-related protein expression. Our data showed that interleukin-10 gene treatment could lighten hepatic fibrosis induced by carbon tetrachloride and induce the aging of activated hepatic stellate cells accompanied by up-regulating the expression of aging-related proteins. We further demonstrated that depletion of p53 could abrogate up-regulation of interleukin-10 on the expression of senescence-related protein in vivo and vitro. Moreover, p53 knockout in fibrotic mice could block not only the senescence of activated hepatic stellate cells, but also the degradation of fibrosis induced by interleukin-10 gene intervention. Taken together, our results suggested that interleukin-10 gene treatment could attenuate carbon tetrachloride-induced hepatic fibrosis by inducing senescence of activated hepatic stellate cells in vivo, and this induction was closely related to p53 signaling pathway.

Functional Inhibition of Natural Killer Cells in a BALB/c Mouse Model of Liver Fibrosis Induced by Schistosoma japonicum Infection

Background and Aims

Schistosomiasis japonica is a widespread human zoonotic disease, and in China, there are many patients with schistosomiasis suffering from liver fibrosis. Many studies have shown that natural killer (NK) cells could reduce the progression of hepatic fibrosis by directly killing hepatic stellate cells (HSCs). However, NK cells could not inhibit the progress of liver fibrosis induced by Schistosoma japonicum infection. We aimed to investigate the function of NK cells in schistosomiasis.

Methods

BALB/c mice were infected with S. japonicum cercariae. The receptors and their proportions expressed on NK cells in the liver and spleen from infected mice were detected using flow cytometry. Levels of IFN-γ, perforin, and granzyme of NK cells, and collagen I, III, and α-SMA of hepatic tissue, were detected using quantitative real-time PCR. Changes in cytokine levels in sera were detected using a cytometric bead array. Liver fibrosis was evaluated using hematoxylin and eosin and Masson staining. NK function in the schistosomiasis model was analyzed.

Results

From 2 to 4 weeks post-infection, NK cells were activated, with significantly increased levels of effector molecules (IFN-γ, perforin, and granzyme) that peaked at 4 weeks after infection. The proportion of NK cells increased in the liver and spleen from 6 to 10 weeks post-infection. However, the function of NK cells was inhibited from 6 to 10 weeks post-infection with significantly decreased levels of activated receptors (AR), inhibitory receptors (IR), and effector molecules. The levels of IFN-γ, IL-12, and IL-6 in mouse serum peaked at 6 weeks post-infection, and IL-10 and IL-21 levels peaked at 8 weeks post-infection. Hepatic fibrosis markers increased significantly at 6 weeks after infection.

Conclusion

Our study suggested that NK cells were activated from 2 to 4 weeks post-infection and participated in inflammation in the mouse model. After the S. japonicum laid their eggs, NK cells became inhibited, with decreased levels of both activating and inhibitory NK cell receptors, as well as cytotoxic molecules. In addition, liver fibrosis formed. In mice infected with S. japonicum, the process of liver fibrosis might be alleviated by removing the functional inhibition of NK cells.

T Cells in Fibrosis and Fibrotic Diseases

Fibrosis is the extensive deposition of fibrous connective tissue, and it is characterized by the accumulation of collagen and other extracellular matrix (ECM) components. Fibrosis is essential for wound healing and tissue repair in response to a variety of triggers, which include infection, inflammation, autoimmune disorder, degenerative disease, tumor, and injury. Fibrotic remodeling in various diseases, such as liver cirrhosis, pulmonary fibrosis, renal interstitial fibrosis, myocardial infarction, systemic sclerosis (SSc), and graft-versus-host disease (GVHD), can impair organ function, causing high morbidity and mortality. Both innate and adaptive immunity are involved in fibrogenesis. Although the roles of macrophages in fibrogenesis have been studied for many years, the underlying mechanisms concerning the manner in which T cells regulate fibrosis are not completely understood. The T cell receptor (TCR) engages the antigen and shapes the repertoire of antigen-specific T cells. Based on the divergent expression of surface molecules and cell functions, T cells are subdivided into natural killer T (NKT) cells, γδ T cells, CD8⁺ cytotoxic T lymphocytes (CTL), regulatory T (Treg) cells, T follicular regulatory (Tfr) cells, and T helper cells, including Th1, Th2, Th9, Th17, Th22, and T follicular helper (Tfh) cells. In this review, we summarize the pro-fibrotic or anti-fibrotic roles and distinct mechanisms of different T cell subsets. On reviewing the literature, we conclude that the T cell regulations are commonly disease-specific and tissue-specific. Finally, we provide perspectives on microbiota, viral infection, and metabolism, and discuss the current advancements of technologies for identifying novel targets and developing immunotherapies for intervention in fibrosis and fibrotic diseases.

Hepatoprotective effects of ZLY16, a dual peroxisome proliferator-activated receptor α/δ agonist, in rodent model of nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD), a chronic progressive liver disease, covers a series of liver damage encompassing steatosis, nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis. However, there are no approved therapies for NAFLD. Herein, we characterize the pharmacological profile of ZLY16 ((E)-2-(4-(3-(2,3-dihydrobenzo[b]thiophen -5-yl)-3-oxoprop-1-en-1-yl)-2,6-dimethylphenoxy)-2-methylpropanoic acid), a novel highly potent PPARα/δ agonist with relative higher potency on PPARγ. The chronic effects of ZLY16 on NASH development were evaluated in MCD-induced db/db mice. ZLY16 revealed decreased liver injury biomarkers, hepatic steatosis, inflammation, ballooning, and oxidative stress. Further mechanism researches suggested that ZLY16 inhibited liver inflammation and fibrosis by regulating gene expression including COLIA1, TIMP, TGFβ, TNFα, and IL6. Moreover, ZLY16 offers more favorable effects in decreasing liver TC and TG accumulation, blocking liver fibrosis and inflammation than GFT505, the most advanced candidate of PPARα/δ agonist for the treatment of NASH. These results indicate that ZLY16 is a highly potent PPARα/δ agonist that provides great protection against NASH development, and may be useful for the treatment of NAFLD/NASH.

Dendrobium officinale Polysaccharide Protected CCl4-Induced Liver Fibrosis Through Intestinal Homeostasis and the LPS-TLR4-NF-κB Signaling Pathway

We explored the therapeutic effects of Dendrobium officinale polysaccharide (DOP) on CCl₄-induced liver fibrosis with respect to the intestinal hepatic axis using a rat model. Histopathological staining results showed that DOP alleviated extensive fibrous tissue proliferation in interstitium and lessened intestinal mucosal damage. Western blot and PCR results showed that DOP maintained intestinal balance by upregulating the expression of tight junction proteins such as occludin, claudin-1, ZO-1, and Bcl-2 proteins while downregulating the expression of Bax and caspase-3 proteins in the intestine. The transepithelial electrical resistance (TEER) value of the LPS-induced Caco-2 monolayer cell model was increased after DOP administration. These illustrated that DOP can protect the intestinal mucosal barrier function. DOP also inhibited activation of the LPS-TLR4-NF-κB signaling pathway to reduce the contents of inflammatory factors TGF-β and TNF-α, increased the expression of anti-inflammatory factor IL-10, and significantly decreased α-SMA and collagen I expression. These results indicated that DOP maintained intestinal homeostasis by enhancing tight junctions between intestinal cells and reducing apoptosis, thereby inhibiting activation of the LPS-TLR4-NF-κB signaling pathway to protect against liver fibrosis.

Intercellular crosstalk of hepatic stellate cells in liver fibrosis: New insights into therapy

Liver fibrosis is a dynamic wound-healing process characterized by the net accumulation of extracellular matrix. There is no efficient antifibrotic therapy other than liver transplantation to date. Activated hepatic stellate cells (HSCs) are the major cellular source of matrix-producing myofibroblasts, playing a central role in the initiation and progression of liver fibrosis. Paracrine signals from resident and inflammatory cells such as hepatocytes, liver sinusoidal endothelial cells, hepatic macrophages, natural killer/natural killer T cells, biliary epithelial cells, hepatic progenitor cells, and platelets can directly or indirectly regulate HSC differentiation and activation. Intercellular crosstalk between HSCs and those "responded" cells has been a critical event involved in HSC activation and fibrogenesis. This review summarizes recent advancement regarding intercellular communication between HSCs and other "responded cells" during liver fibrosis and experimental models of intercellular crosstalk systems, and provides novel ideas for potential antifibrotic therapeutic strategy.

Vitis vinifera polyphenols from seedless black fruit act synergistically to suppress hepatotoxicity by targeting necroptosis and pro-fibrotic mediators

Human is subjected from his surrounding to various hepatotoxins, which aggravates his liver. Nowadays, natural polyphenols have attracted great interest in health improvement, especially liver health. The present research, therefore, assessed the hepatotherapeutic potency of the isolated polyphenols (VVF1) from seedless (pulp and skin) black Vitis vinifera (VV) against CCl4-induced hepatotoxicity in vitro and in vivo. Further, VVF1 was fractionated into resveratrol-enriched (VVF2) and phenolics-enriched (VVF3) fractions to study (in vitro) the possible synergism of their coexistence. The highest content of phenolics in VVF1 displayed in vitro synergistic antioxidant and anti-hepatotoxic activities comparing to VVF2, VVF3, and silymarin (SM, reference drug). More importantly, it exhibited multiple in vivo regulatory functions via diminishing oxidative stress and inflammation, which in turn decreased necroptosis and pro-fibrotic mediators (mixed lineage kinase domain-like protein (MLKL), collagen type I alpha 1 chain (COL1A1), and transforming growth factor (TGF)-β1). In addition to these novel findings, VVF1 had higher anti-hepatotoxic potency than that of SM in most of the studied parameters. The histopathological analysis confirmed the improving role of VVF1 in the serious hepatic damage induced by CCl4. Thus, the synergistic functions of VVF1 polyphenols could be a promising new anti-hepatotoxic agent for targeting both necroptotic and profibrotic mediators.

TWEAK promotes hepatic stellate cell migration through activating EGFR/Src and PI3K/AKT pathways

Activated human hepatic stellate cells (HSCs) showed enhanced ability of migration compared with quiescent HSCs, which is pivotal in liver fibrogenesis. The aim of the present study was to investigate the effects of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) on the migration of activated HSCs and to explore the relevant potential mechanisms. Human HSCs LX-2 cells were cultured with TWEAK. TNFRSF12A-downexpressing lentiviruses were used to infect LX-2 cells. The specific matrix metalloproteinases inhibitor BB94, the Src family kinase inhibitor, Dasatinib, and the specific inhibitor of phosphoinositide 3-kinase (PI3K), LY294002 were used to treat LX-2 cells combined with TWEAK. Cell migration and invasion was tested by the transwell assay. The expression of EGFR/Src, PI3K/AKT, and matrix metallopeptidase 9 (MMP9) was identified by real-time polymerase chain reaction or western blotting. The result showed TWEAK promoted HSC migration and collagen production. BB94 significantly attenuated the migration of LX-2 induced by TWEAK. Dasatinib inhibited the ability of cell migration stimulated by TWEAK. TWEAK upregulated the phosphorylation of epidermal growth factor receptor (EGFR) and Src. The phosphorylation of PI3K and AKT was significantly activated by TWEAK stimulation. Inhibition of PI3K/AKT reduced the expression of MMP9 induced by TWEAK. The present study, for the first time, demonstrated that TWEAK promoted HSC migration through the activation of EGFR/Src and PI3K/AKT pathways, and showed a novel potential mechanism of HSC migration regulated by TWEAK.

Relation Between Immunohistochemical Expression of Hippo Pathway Effectors and Chronic Hepatitis Induced Fibrosis in Egyptian Patients

OBJECTIVE

Chronic hepatitis is a global health problem especially in Egypt. Hepatic fibrosis is a common end clinical manifestation of many chronic liver diseases. Although it is a wound-healing process, excessive accumulation of fibrillary collagen leads to architectural damage, cirrhosis and liver failure. Recently, a few studies have linked Hippo pathway effectors of yes-associated protein (YAP) and its paralog transcriptional coactivator with PDZ-binding motif (TAZ) to extracellular matrix deposition and ongoing fibrosis.

MATERIAL AND METHOD

Immunohistochemical expression of YAP and TAZ were analyzed in 121 liver needle core biopsies (91 core biopsies of chronic viral hepatitis, 20 biopsies of autoimmune hepatitis and 10 normal liver cores).

RESULTS

YAP and TAZ nuclear localization was absent in all normal liver cores. Autoimmune hepatitis cases showed higher nuclear expression of both YAP and TAZ in comparison to chronic viral cases. YAP and TAZ expression were correlated with severity of hepatocyte injury together with fibrosis in chronic viral cases but these correlations were absent in AIH cases despite the pronounced increase of YAP and TAZ nuclear localization.

CONCLUSION

The correlation between Hippo effectors activation and fibrosis in chronic viral hepatitis patients emphasize their role in the development and advancement of hepatic scarring and highlight the use of both YAP and TAZ as novel targets to ameliorate liver fibrosis.

cDC1 IL-27p28 Production Predicts Vaccine-Elicited CD8+ T Cell Memory and Protective Immunity

Although adjuvants and formulations are often either empirically derived, or at best judged by their ability to elicit broad inflammation, it would be ideal if specific innate correlates of adaptive immunity could be identified to set a universally applicable benchmark for adjuvant evaluation. Using an IL-27 reporter transgenic mouse model, we show in this study that conventional type 1 dendritic cell IL-27 production in the draining lymph node 12 h after s.c. vaccination directly correlates with downstream CD8⁺ T cell memory and protective immunity against infectious challenge. This correlation is robust, reproducible, predictive, entirely unique to vaccine biology, and is the only innate correlate of CD8⁺ T cell immune memory yet to be identified. Our results provide new insights into the basic biology of adjuvant-elicited cellular immunity and have clear implications for the screening and evaluation of novel adjuvants.

Impact of Interleukin-27p28 on T and B Cell Responses during Toxoplasmosis

Interleukin-27 (IL-27) is a heterodimeric cytokine composed of the subunits IL-27p28 and EBi3, and while the IL-27 heterodimer influences T cell activities, there is evidence that IL-27p28 can have EBi3-independent activities; however, their relevance to infection is unclear. Therefore, the studies presented here compared how IL-27p28 transgenics and IL-27p28-/- mice responded to the intracellular parasite Toxoplasma gondii While the loss of IL-27p28 and its overexpression both result in increased susceptibility to T. gondii, the basis for this phenotype reveals distinct roles for IL-27p28. As a component of IL-27, IL-27p28 is critical to limit infection-induced T cell-mediated pathology, whereas the ectopic expression of IL-27p28 reduced the effector T cell population and had a major inhibitory effect on parasite-specific antibody titers and a failure to control parasite replication in the central nervous system. Indeed, transfer of immune serum to infected IL-27p28 transgenics resulted in reduced parasite burden and pathology. Thus, IL-27p28, independent of its role as a component of IL-27, can act as a negative regulator of humoral and cellular responses during toxoplasmosis.

IL-27, IL-30, and IL-35: A Cytokine Triumvirate in Cancer

The role of the immune system in anti-tumor immunity cannot be overstated, as it holds the potential to promote tumor eradication or prevent tumor cell escape. Cytokines are critical to influencing the immune responses and interactions with non-immune cells. Recently, the IL-12 and IL-6 family of cytokines have accumulated newly defined members each with specific immune functions related to various cancers and tumorigenesis. There is a need to better understand how cytokines like IL-27, IL-30, and IL-35 interact with one another, and how a developing tumor can exploit these interactions to enhance immune suppression. Current cytokine-based immunotherapies are associated with cytotoxic side effects which limits the success of treatment. In addition to this toxicity, understanding the complex interactions between immune and cancer cells may be one of the greatest challenges to developing a successful immunotherapy. In this review, we bring forth IL-27, IL-30, and IL-35, “sister cytokines,” along with more recent additions to the IL-12 family, which serve distinct purposes despite sharing structural similarities. We highlight how these cytokines function in the tumor microenvironment by examining their direct effects on cancer cells as well their indirect actions via regulatory functions of immune cells that act to either instigate or inhibit tumor progression. Understanding the context dependent immunomodulatory outcomes of these sister cytokines, as well as their regulation within the tumor microenvironment, may shed light onto novel cancer therapeutic treatments or targets.

Tissue-resident mesenchymal stromal cells: Implications for tissue-specific antifibrotic therapies

Recent scientific findings support the notion that fibrosis is driven by tissue-specific cellular and molecular mechanisms. Analysis of seemingly equivalent mesenchymal stromal cell (MSC) populations residing in different organs revealed unique properties and lineage capabilities that vary from one anatomical location to another. We review recently characterized tissue-resident MSC populations with a prominent role in fibrosis and highlight therapeutically relevant molecular pathways regulating their activity in chronic disease.

Crosstalk network among multiple inflammatory mediators in liver fibrosis

Liver fibrosis is the common pathological basis of all chronic liver diseases, and is the necessary stage for the progression of chronic liver disease to cirrhosis. As one of pathogenic factors, inflammation plays a predominant role in liver fibrosis via communication and interaction between inflammatory cells, cytokines, and the related signaling pathways. Damaged hepatocytes induce an increase in pro-inflammatory factors, thereby inducing the development of inflammation. In addition, it has been reported that inflammatory response related signaling pathway is the main signal transduction pathway for the development of liver fibrosis. The crosstalk regulatory network leads to hepatic stellate cell activation and proinflammatory cytokine production, which in turn initiate the fibrotic response. Compared with the past, the research on the pathogenesis of liver fibrosis has been greatly developed. However, the liver fibrosis mechanism is complex and many pathways involved need to be further studied. This review mainly focuses on the crosstalk regulatory network among inflammatory cells, cytokines, and the related signaling pathways in the pathogenesis of chronic inflammatory liver diseases. Moreover, we also summarize the recent studies on the mechanisms underlying liver fibrosis and clinical efforts on the targeted therapies against the fibrotic response.

Knockout of α-calcitonin gene-related peptide attenuates cholestatic liver injury by differentially regulating cellular senescence of hepatic stellate cells and cholangiocytes

α-Calcitonin gene-related peptide (α-CGRP) is a 37-amino acid neuropeptide involved in several pathophysiological processes. α-CGRP is involved in the regulation of cholangiocyte proliferation during cholestasis. In this study, we aimed to evaluate if α-CGRP regulates bile duct ligation (BDL)-induced liver fibrosis by using a α-CGRP knockout (α-CGRP^-/-) mouse model. α-CGRP^-/- and wild-type (WT) mice were subjected to sham surgery or BDL for 7 days. Then, liver fibrosis and cellular senescence as well as the expression of kinase such as p38 and C-Jun N-terminal protein kinase (JNK) in mitogen-activated protein kinases (MAPK) signaling pathway were evaluated in total liver, together with measurement of cellular senescence in cholangiocytes or hepatic stellate cells (HSCs). There was enhanced hepatic expression of Calca (coding α-CGRP) and the CGRP receptor components (CRLR, RAMP-1 and RCP) in BDL and in both WT α-CGRP^-/- and BDL α-CGRP^-/- mice, respectively. Moreover, there was increased CGRP serum levels and hepatic mRNA expression of CALCA and CGRP receptor components in late-stage PSC samples compared to healthy control samples. Depletion of α-CGRP reduced liver injury and fibrosis in BDL mice that was associated with enhanced cellular senescence of hepatic stellate cells and reduced senescence of cholangiocytes as well as decreased activation of p38 and JNK MAPK signaling pathway. Cholangiocyte supernatant from BDL α-CGRP^-/- mice inhibited the activation and increased cellular senescence of cultured human HSCs (HHSCs) compared to HHSCs stimulated with BDL cholangiocyte supernatant. Taken together, endogenous α-CGRP promoted BDL-induced cholestatic liver fibrosis through differential changes in senescence of HSCs and cholangiocytes and activation of p38 and JNK signaling. Modulation of α-CGRP/CGRP receptor signaling may be key for the management of biliary senescence and liver fibrosis in cholangiopathies.

Hyperactivated peripheral invariant natural killer T cells correlate with the progression of HBV-relative liver cirrhosis

Invariant NKT (iNKT) cells express markers of both T and NK cells and may produce various cytokines to regulate liver immunity. However, the role of iNKT cells in the progression of HBV-relative liver cirrhosis (HBV-LC) is incompletely understood. Here, we investigated the impact of peripheral iNKT cells on a cohort of patients with HBV-LC. The frequency, number, activation status, apoptosis and proliferation ability of peripheral iNKT cells were detected with flow cytometry. The impact of peripheral iNKT cells on the proliferation of hepatocyte cell line (MIHA) and activation of hepatic stellate cell line (LX-2) was detected with flow cytometry and PCR. In HBV-LC patients, the frequency and absolute number of peripheral iNKT cells significantly reduced, but the expression levels of CD25, interleukin (IL)-4, IL-13 and interferon (IFN)-γ increased. No difference was observed in the proliferation and apoptosis of circulating iNKT cells between patients and healthy controls (HCs). CXCR6 (CD186), known to be closely associated with iNKT cells migration from the periphery to the liver, was highly expressed on peripheral iNKT cells in HBV-LC patients. Furthermore, peripheral iNKT cells had a profound impact on MIHA cell proliferation and LX-2 cell activation through IL-4 or IL-13. Our data suggest that in HBV-LC patients, highly activated peripheral iNKT cells may migrate to the liver and affect hepatocyte cell line (MIHA) proliferation and hepatic stellate cell line (LX-2) activation through the expression of type 2 cytokines, which may result in excessive healing and contributing to the progression of fibrosis toward cirrhosis in liver.

Activated NK cells kill hepatic stellate cells via p38/PI3K signaling in a TRAIL-involved degranulation manner

NK cells are important in regulating hepatic fibrosis via their cytotoxic killing of hepatic stellate cells (HSCs). NK cells are activated by both cytokines such as IL-12 and IL-18, and innate immune stimuli such as ligation of TLRs. The secretion of IL-18 depends upon activation of the inflammasome, whereas TLRs are stimulated by microbial products. In the case of NK cells, IL-18 acts synergistically with stimulation of TLR3 to cause cell activation and cytotoxic function. In the present study, we activated NK cells to kill HSCs via IL-18 and TLR3 ligand stimulation, and dissected the signaling pathways or molecules critical for such activation or killing. We find that such activation depends on signaling via the p38/PI3K/AKT pathway, and that the activated NK cells mediate HSC death in a TRAIL-involved mechanism. As liver fibrosis is a major global health problem with no good solution, these results emphasize that the p38/PI3K/AKT pathway in NK cells may be a novel drug target to promote fibrosis regression.

A folding switch regulates interleukin 27 biogenesis and secretion of its α-subunit as a cytokine

A common design principle of heteromeric signaling proteins is the use of shared subunits. This allows encoding of complex messages while maintaining evolutionary flexibility. How cells regulate and control assembly of such composite signaling proteins remains an important open question. An example of particular complexity and biological relevance is the interleukin 12 (IL-12) family. Four functionally distinct αβ heterodimers are assembled from only five subunits to regulate immune cell function and development. In addition, some subunits act as independent signaling molecules. Here we unveil key molecular mechanisms governing IL-27 biogenesis, an IL-12 family member that limits infections and autoimmunity. In mice, the IL-27α subunit is secreted as a cytokine, whereas in humans only heterodimeric IL-27 is present. Surprisingly, we find that differences in a single amino acid determine if IL-27α can be secreted autonomously, acting as a signaling molecule, or if it depends on heterodimerization for secretion. By combining computer simulations with biochemical experiments, we dissect the underlying structural determinants: a protein folding switch coupled to disulfide bond formation regulates chaperone-mediated retention versus secretion. Using these insights, we rationally change folding and assembly control for this protein. This provides the basis for a more human-like IL-27 system in mice and establishes a secretion-competent human IL-27α that signals on its own and can regulate immune cell function. Taken together, our data reveal a close link between protein folding and immunoregulation. Insights into the underlying mechanisms can be used to engineer immune modulators.

rSjP40 suppresses hepatic stellate cell activation by promoting microRNA-155 expression and inhibiting STAT5 and FOXO3a expression

Activation of hepatic stellate cells (HSCs) is the central event of the evolution of hepatic fibrosis. Schistosomiasis is one of the pathogenic factors which could induce hepatic fibrosis. Previous studies have shown that recombinant Schistosoma japonicum egg antigen P40 (rSjP40) can inhibit the activation and proliferation of HSCs. MicroRNA‐155 is one of the multifunctional noncoding RNA, which is involved in a series of important biological processes including cell development, proliferation, differentiation and apoptosis. Here, we try to observe the role of microRNA‐155 in rSjP40‐inhibited HSC activation and explore its potential mechanisms. We found that microRNA‐155 was raised in rSjP40‐treated HSCs, and further studies have shown that rSjP40 enhanced microRNA‐155 expression by inhibiting STAT5 transcription. Up‐regulated microRNA‐155 can down‐regulate the expression of FOXO3a and then participate in rSjP40‐inhibited expression of α‐smooth muscle actin (α‐SMA) and collagen I. Furthermore, we observed microRNA‐155 inhibitor could partially restore the down‐regulation of FOXO3a, α‐SMA and collagen I expression in LX‐2 cells induced by rSjP40. Therefore, our research provides further insight into the mechanism by which rSjP40 could inhibit HSC activation via miR‐155.

Salvia Miltiorrhiza Ameliorates Liver Fibrosis by Activating Hepatic Natural Killer Cells in Vivo and in Vitro

Natural killer (NK) cells are known for their ability to kill activated hepatic stellate cells (HSCs), which has been confirmed both in patients and animal models. But the killing function is depressed in period of advanced liver injury. Salvia Miltiorrhiza (SM), a Chinese herbal medicine for invigorating blood circulation and eliminating stasis, is widely used to treat liver fibrosis in clinic. Nevertheless, the immunological mechanism remains unclearly. Here, we put forward the hypothesis that the anti-fibrotic effect of SM is concerned with boosting the activation of hepatic NK cells. Liver fibrosis was induced with carbon tetrachloride (CCl₄) and effects of SM on NK cells and HSC (JS-1 cell line, HSC) were investigated in vivo and in vitro. Hepatic NK cells were isolated from C57BL/6 mice, and pre-incubated with SM before they were co-cultured with HSCs. We found that SM increased frequency of NK cells, enhanced activities of NKG2D and Nkp46 on NK cells and inhibited activation of HSCs in vivo and in vitro. SM could promote the activities of NK cells by increasing the expressions of NKG2D and IFN-γ before or after co-cultured with HSCs in vitro. Besides, SM could partially antagonize ASGM-1-induced NK cell depletion and enhance the cell activities to inhibit HSCs activation in vitro. Therefore, our work provided a new insight into the anti-fibrotic mechanism that SM could enhance the activities of NK cell to reduce liver fibrosis in vivo and in vitro.

IL-17 enhances oxidative stress in hepatocytes through Nrf2/keap1 signal pathway activation

Hepatic disease is common worldwide. As apoptosis of hepatocytes is a hallmark of hepatic disease, strategies targeting apoptosis are an effective way to prevent and treat the disease. Oxidative stress is a classic pathway of apoptosis. Increased expression of IL-17 has been found in diverse human liver diseases. The aim of this research was to investigate whether the function of IL-17 influenced hepatocyte-induced H₂O₂. We found that the expression of IL-17 was enhanced in hepatocyte-induced H₂O₂ and that IL-17 was down-regulated by siRNA. A TUNEL assay showed that apoptosis was decreased in ΔIL-17-mutant hepatocyte-induced H₂O₂. Additionally, the ratio of Bax/Bcl-2 was decreased in ΔIL-17-mutant hepatocyte-induced H₂O₂. Finally, Nrf2/keap1 signal pathway was analyzed, the expression of Nrf2 and keap1 was decreased in ΔIL-17-mutant hepatocyte-induced H₂O₂. These results suggest that oxidative stress-induced apoptosis was induced and that IL-17 could enhance oxidative stress-induced apoptosis by the Nrf2/keap1 signal pathway in hepatocytes.

Critical Contribution of NK Group 2 Member D Expressed on Invariant Natural Killer T Cells in Concanavalin A-Induced Liver Hepatitis in Mice

Natural killer group 2D (NKG2D) is a well-characterized activating receptor expressed on many immune cells, including invariant natural killer T (iNKT) cells. These cells were shown to be responsible of liver injury in the model of concanavalin A (Con A)-induced hepatitis, considered to be an experimental model of human autoimmune hepatitis. In this study, we investigated whether NKG2D plays a role in the hepatitis induced by iNKT cell-mediated immune response to Con A. By using killer cell lectin-like receptor subfamily K, member 1 deficient (Klrk1^−/−) mice, we found that the absence of NKG2D reduced the hepatic injury upon Con A administration. This was not due to an intrinsic functional defect of NKG2D-deficient iNKT cells as mice missing NKG2D have normal distribution and function of iNKT cells. Furthermore, increased resistance to Con A-induced hepatitis was confirmed using neutralizing anti-NKG2D antibodies. The reduced pathogenic effect of Con A in the absence of NKG2D correlates with a reduction in pathogenic cytokine production and FAS-Ligand (FAS-L) expression by iNKT cells. We also found that Con A administration led to an increase in the retinoic acid early inducible (RAE-1) surface expression on wild-type hepatocytes. Finally, we found that Con A has no direct action on FAS-L expression or cytokine production by iNKT cells and thus propose that NKG2D-L expression on stressed hepatocytes promote cytotoxic activity of iNKT cells via its interaction with NKG2D contributing to hepatic injury. In conclusion, our results highlight NKG2D as an essential receptor required for the activation of iNKT cells in Con A-induced hepatitis and indicate that it represents a potential drug target for prevention of autoimmune hepatitis.