Th17 cells: the emerging reciprocal partner of regulatory T cells in the liver

Interleukin 28A aggravates Con A-induced acute liver injury by promoting the recruitment of M1 macrophages

Immune-mediated acute hepatic injury is characterized by the destruction of a large number of hepatocytes and severe liver function damage. Interleukin-28A (IL-28A), a member of the IL-10 family, is notable for its antiviral properties. However, despite advances in our understanding of IL-28A, its role in immune-mediated acute injury remains unclear. The present study investigated the role of IL-28A in concanavalin A (Con A)-induced acute immune liver injury. After Con A injection in mice, IL-28A level significantly increased. IL-28A deficiency was found to protect mice from acute liver injury, prolong survival time, and reduce serum aspartate aminotransferase and alanine aminotransferase levels. In contrast, recombinant IL-28A aggravated liver injury in mice. The proportion of activated M1 macrophages was significantly lower in the IL-28A-deficiency group than in the wild-type mouse group. In adoptive transfer experiments, M1 macrophages from WT could exacerbate mice acute liver injury symptoms in the IL-28A deficiency group. Furthermore, the expression of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), IL-12, IL-6, and IL-1β, by M1 macrophages decreased significantly in the IL-28A-deficiency group. Western blotting demonstrated that IL-28A deficiency could limit M1 macrophage polarization by modulating the nuclear factor (NF)-κB, mitogen-activated protein kinase (MAPK), and interferon regulatory factor (IRF) signaling pathways. In summary, IL-28A deletion plays an important protective role in the Con A-induced acute liver injury model and IL-28A deficiency inhibits the activation of M1 macrophages by inhibiting the NF-κB, MAPK, and IRF signaling pathways. These results provide a potential new target for the treatment of immune-related hepatic injury.

Mechanisms of cancer cell death induction by triptolide: A comprehensive overview

The need for naturally occurring constituents is driven by the rise in the cancer prevalence and the unpleasant side effects associated with chemotherapeutics. Triptolide, the primary active component of "Tripterygium Wilfordii", has exploited for biological mechanisms and therapeutic potential against various tumors. Based on the recent pre-clinical investigations, triptolide is linked to the induction of death of cancerous cells by triggering cellular apoptosis via inhibiting heat shock protein expression (HSP70), and cyclin dependent kinase (CDKs) by up regulating expression of P21. MKP1, histone methyl transferases and RNA polymerases have all recently identified as potential targets of triptolide in cells. Autophagy, AKT signaling pathway and various pathways involving targeted proteins such as A-disintegrin & metalloprotease-10 (ADAM10), Polycystin-2 (PC-2), dCTP pyro-phosphatase 1 (DCTP1), peroxiredoxin-I (Prx-I), TAK1 binding protein (TAB1), kinase subunit (DNA-PKcs) and the xeroderma-pigmentosum B (XPB or ERCC3) have been exploited. Besides that, triptolide is responsible for enhancing the effectiveness of various chemotherapeutics. In addition, several triptolide moieties, including minnelide and LLDT8, have progressed in investigations on humans for the treatment of cancer. Targeted strategies, such as triptolide conjugation with ligands or triptolide loaded nano-carriers, are efficient techniques to confront toxicities associated with triptolide. We expect and anticipate that advances in near future, regarding combination therapies of triptolide, might be beneficial against cancerous cells.

Multicytokine-producing CD4+ T cells characterize the livers of patients with NASH

A role of CD4+ T cells during the progression from nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) has been suggested, but which polarization state of these cells characterizes this progression and the development of fibrosis remain unclear. In addition, a gut-liver axis has been suggested to play a role in NASH, but the role of CD4+ T cells in this axis has just begun to be investigated. Combining single-cell RNA sequencing and multiple-parameter flow cytometry, we provide the first cell atlas to our knowledge focused on liver-infiltrating CD4+ T cells in patients with NAFLD and NASH, showing that NASH is characterized by a population of multicytokine-producing CD4+ T cells. Among these cells, only those with a Th17 polarization state were enriched in patients with advanced fibrosis. In parallel, we observed that Bacteroides appeared to be enriched in the intestine of NASH patients and to correlate with the frequency of multicytokine-producing CD4+ T cells. In short, we deliver a CD4+ T cell atlas of NAFLD and NASH, providing the rationale to target CD4+ T cells with a Th17 polarization state to block fibrosis development. Finally, our data offer an early indication to test whether multicytokine-producing CD4+ T cells are part of the gut-liver axis characterizing NASH.

Narciclasine ameliorated T cell mediated acute liver injury through activating AMPK pathway

Hepatitis is closely related to cirrhosis and liver cancer, and it is vital that we develop new drugs and identify new drug targets. Traditional Chinese medicine has demonstrated excellent curative effects on liver diseases. The ingredients from Chinese herbals are important source for drug development in the treatment of hepatitis. Here, we found that narciclasine (NCS), a major component extracted from narcissus bulbs, showed hepatoprotective effect against concanavalin A (Con A) induced hepatitis. NCS treatment significantly reduced hepatocyte death, hepatic inflammatory cells infiltration, and serum cytokine levels in Con A challenged mice. We further observed that NCS directly inhibited Con A induced splenocytes proliferation and cytokine production in vitro. RNA-seq results showed that genes related to immune response were upregulated in Con A treated CD4⁺ T cells, which were down-regulated in the presence of NCS. Moreover, the AMPK pathway had been found activated in response to NCS treatment, suggesting a potential target for NCS targets. In conclusion, our results reveal that NCS is a powerful immunosuppressor against T cell activation, thus leading to protection against Con A induced liver injury in mice. These findings provide new insights into the use of natural products in the treatment of autoimmune hepatitis.

Adipose-Derived Stem Cell Exosomes Inhibit Hypertrophic Scaring Formation by Regulating Th17/Treg Cell Balance

Aiming to reveal the role of ADCS-Exos in secretion of inflammatory factors, Th17 and regulatory T (Treg) cell differentiation from naïve CD4+ T cells in hypertrophic scaring formation and maturation is explored. ELISA, qRT-PCR, and immunoblotting are performed to assay the local inflammatory factors IL-6, IL-10, IL-17A, and TNF-α, and transcriptional factors of RORϒt and Foxp3, in scaring tissue from patients and mice wound models treated with or without ADCS-Exos. Immunohistochemistry staining and immunoblotting are conducted to assay the extracellular matrix (ECM) deposition in vitro and in vivo. The results show that IL-6, IL-10, IL-17A, TNF-α, RORϒt, and Foxp3 are increased on mRNA and protein levels in hypertrophic scaring compared with atrophic scaring and normal skin. Naïve CD4⁺ T cells treated with ADCS-Exos in vitro can produce significantly less IL-6, IL-17A, TNF-α, and RORϒt and more IL-10 and Foxp3 on mRNA and protein levels. In addition, mice in ADSC-Exos-treated group demonstrate less collagen deposition; decreased IL-17A, TNF-α, and RORϒt; and increased IL-10 and Foxp3 production.

Inflammatory response of gut, spleen, and liver in mice induced by orally administered Porphyromonas gingivalis

Background

Periodontitis is a chronic multifactorial inflammatory disease. Porphyromonas gingivalis is a primary periopathogen in the initiation and development of periodontal disease. Evidence has shown that P. gingivalis is associated with systemic diseases, including IBD and fatty liver disease. Inflammatory response is a key feature of diseases related to this species.

Methods

C57BL/6 mice were administered either PBS, or P. gingivalis. After 9 weeks, the inflammatory response in gut, spleen, and liver was analyzed.

Results

The findings revealed significant disturbance of the intestinal microbiota and increased inflammatory factors in the gut of P. gingivalis-administered mice. Administrated P. gingivalis remarkably promoted the secretion of IRF-1 and activated the inflammatory pathway IFN-γ/STAT1 in the spleen. Histologically, mice treated with P. gingivalis exhibited hepatocyte damage and lipid deposition. The inflammatory factors IL-17a, IL-6, and ROR-γt were also upregulated in the liver of mice fed with P. gingivalis. Lee’s index, spleen index, and liver index were also increased.

Conclusion

These results suggest that administrated P. gingivalis evokes inflammation in gut, spleen, and liver, which might promote the progression of various systemic diseases.

Detoxification strategies of triptolide based on drug combinations and targeted delivery methods

Tripterygium wilfordii Hook f. has a long history of use in Chinese medicine. Triptolide (TP), as its main pharmacological component, has been widely explored in various diseases, including systemic lupus erythematosus, rheumatoid arthritis and cancer. However, due to its poor water solubility, limited therapeutic range and multi-organ toxicity, TP's clinical application has been greatly hampered. To improve its clinical potential, many attenuated drug combinations have been developed based on its toxicity mechanism and targeted delivery systems aimed at its water-solubility and structure. This review, conducted a systematic review of TP detoxification strategies including drug combination detoxification strategies from metabolic and toxic mechanisms, as well as drug delivery detoxification strategies from the prodrug strategy and nanotechnology. Many detoxification strategies have demonstrated promising potential in vitro and in vivo due to previous extensive studies on TP. Therefore, summarizing and discussing TP detoxification strategies for clinical problems can serve as a reference for developing novel TP detoxification strategies, and provide opportunities for future clinical applications.

MIG/CXCL9 exacerbates the progression of metabolic-associated fatty liver disease by disrupting Treg/Th17 balance

CD4⁺CD25⁺ regulatory T (Treg) cells and Th17 cells play important roles in the progression of metabolic-associated fatty liver disease (MAFLD). However, the contribution of monokine induced by interferon-gamma (MIG)/CXCL9 to the Treg/Th17 imbalance in MAFLD is only partially understood. In the present study, we detected increased levels of MIG/CXCL9 and a Treg/Th17 imbalance in the setting of metabolic-associated steatohepatitis (MASH). Recombinant adeno-associated virus-mediated gene transfer and silencing of MIG/CXCL9 expression in mice alleviated MASH and increased the Treg/Th17 ratio. Furthermore, the percentage of Th17 cells, but not Treg cells, differentiated from splenic CD4⁺ T cells was significantly increased by administration of MIG/CXCL9. MIG/CXCL9 also promoted Th17 cell proliferation, and its effects were dose dependent. Levels of phosphorylated c-Jun N-terminal kinase (JNK) decreased dramatically when MIG/CXCL9 was inhibited in a murine MASH model. In cultured Treg cells, phosphorylated JNK levels decreased dose-dependently in response to MIG/CXCL9 inhibition, but increased in cultured Th17 cells. This effect was blocked in the presence of a JNK inhibitor. These findings underline the fundamental importance of MIG/CXCL9 in maintaining the Treg/Th17 balance in MAFLD and provide the foundations for a novel approach to preventing and treating MAFLD.

The inflammatory response of the supraspinatus muscle in rotator cuff tear conditions

BACKGROUND

Rotator cuff (RC) disorders involve a spectrum of shoulder conditions from early tendinopathy to full-thickness tears leading to impaired shoulder function and pain. The pathology of RC disorder is, nonetheless, still largely unknown. Our hypothesis is that a supraspinatus (SS) tendon tear leads to sustained inflammatory changes of the SS muscle along with fatty infiltration and muscle degeneration, which are threshold markers for poor RC muscle function. The aim of this study was to determine the extent of this muscle inflammation in conjunction with lipid accumulation and fibrosis in RC tear conditions.

METHODS

We used proteomics, histology, electrochemiluminescence immunoassay, and quantitative polymerase chain reaction analyses to evaluate inflammatory and degenerative markers and fatty infiltration in biopsies from 22 patients undergoing surgery with repair of a full-thickness SS tendon tear.

RESULTS

Bioinformatic analysis showed that proteins involved in innate immunity, extracellular matrix organization, and lipid metabolism were among the most upregulated, whereas mitochondrial electronic transport chain along with muscle fiber function was among the most downregulated. Histologic analysis confirmed changes in muscle fiber organization and the presence of inflammation and fatty infiltration. Inflammation appeared to be driven by a high number of infiltrating macrophages, accompanied by elevated matrix metalloprotease levels and changes in transforming growth factor-β and cytokine levels in the SS compared with the deltoid muscle.

CONCLUSIONS

We demonstrated massive SS muscle inflammation after the tendon tear combined with fatty infiltration and degeneration. The regulation of tissue repair is thus extremely complex, and it may have opposite effects at different time points of healing. Inhibition or stimulation of muscle inflammation may be a potential target to enhance the outcome of the repaired torn RC.

Alterations in Th17 and Treg Lymphocyte Subset in Workers Occupationally Exposed to Lead

Occupational exposure to lead (Pb) may have a deleterious effect on health of the workers. Among the various physiological systems, the immune system is one of the most susceptible targets of lead. Previous studies have been inconclusive in establishing the effect of Pb on the immune system. With this background, the aim of our study was to determine the effect of occupational Pb exposure on workers' immune parameters. A total of 110 individuals who were occupationally exposed to Pb and 97 apparently healthy non-exposed individuals were recruited in this study. Blood lead levels (BLL) were determined by atomic absorption spectrophotometry (AAS). Lymphocyte subsets (Th1, Th17, and Tregs) were analyzed using flow cytometry, and the cytokine levels (IL-2, IL-4, IL-6, IL-10, IL-17, and TNF-α) were determined by ELISA. BLL were found to be significantly higher in the exposed group than non-exposed. A significant increase of CD8 cells (%) was observed in the lead-exposed group, while CD4 cells (%), although higher in the exposed group did not differ significantly. Among the T lymphocyte subsets, proportion of Th1 and Tregs was found to be lower in the exposed group with a significant increase in Th17 (%). Additionally, the levels of estimated cytokines suggested a predominant pro-inflammatory response in Pb-exposed workers with significant increase in IL-4, IL-6, and TNF-α, and a significant decrease in IL-2 and IL-10. IL-17 levels did not show any significant difference between the two groups. Increased Th17/Tregs ratio in the exposed group is also suggestive of an increased pro-inflammatory immune response in the exposed group. In conclusion, Pb exposure may induce functional alteration in the immune cells, which may predispose to other abnormalities.

Hepatic lymphocytes involved in the pathogenesis of pediatric and adult non-alcoholic fatty liver disease

The immune response is critical in NAFLD pathogenesis, but the liver infiltrate's composition and the role of each T cell population is still up for debate. To characterize liver pathogenesis in pediatric and adult cases, frequency and localization of immune cell populations [Cytotoxic T Lymphocytes (CD8+), T helper Lymphocytes (CD4+), Regulatory T lymphocytes (Foxp3+) and Th17 (IL-17A+)] were evaluated. In portal/periportal (P/P) tracts, both age groups displayed a similar proportion of CD8+ and CD4+ lymphocytes. However, comparable Foxp3+ and IL-17A+ cell frequencies were observed in pediatric cases, meanwhile, in adults Foxp3+ was higher than IL-17A+ cells. Interestingly, IL-17A+ lymphocytes seemed to be nearly exclusive of P/P area in both age groups. In intralobular areas, both pediatric and adult cases showed CD8+ lymphocytes predominance with lower frequencies of CD4+ lymphocytes followed by Foxp3+ . Severe inflammation was associated with higher intralobular Foxp3+ lymphocytes (p = 0.026) in children, and lower P/P Foxp3+ and higher IL-17A+ lymphocytes in adults. All cases with fibrosis ≥ 2 displayed P/P low Foxp3+ and high IL-17A+ lymphocyte counts. Pediatric cases with worse steatosis showed high P/P CD4+ (p = 0.023) and intralobular CD8+ (p = 0.027) and CD4+ cells (p = 0.012). In NAFLD cases, the lymphocyte liver infiltrate composition differs between histological areas. Treg and Th17 balance seems to condition damage progression, denoting their important role in pathogenesis.

Estimation of lymphocyte subsets and cytokine levels in workers occupationally exposed to cadmium

INTRODUCTION

Occupational exposure to Cadmium (Cd) may have serious health effect on workers. However, little is known about its effect on immune system. Moreover, previous studies have been inconclusive in stating the effect of Cd on immune system. The aim of our study was to estimate immune parameters in workers occupationally exposed to Cd.

MATERIAL AND METHODS

110 individuals occupationally exposed to Cd and 97 apparently healthy non-exposed individuals were recruited for this study. Blood Cadmium levels were determined by AAS. Lymphocyte subset were analyzed using flow cytometry and the cytokine levels were determined by ELISA.

RESULTS

Exposed group have significantly higher levels of B-Cd. % of CD8 cells were higher in exposed while % of CD4 cells showed a decreasing trend in the exposed group. Among the CD3CD4 T cell subsets Th1 (%) and Tregs (%) cells were lower while Th17 (%) were higher in exposed group. Increased levels of IL-4 (Th2), IL-6 (Th2) and TNF- α (Th1) and decreased levels of IL-2 (Th1) and IL-10 (Tregs) were observed in Cd exposed workers which is indicative of a predominant pro-inflammatory response in Cd exposed workers. IL-17 (Th17) levels did not show any significant difference between the two groups. Increased Th17/Tregs ratio in the exposed group is also suggestive of an increased pro-inflammatory immune response in exposed group.

CONCLUSION

To conclude, even low level of exposure to Cd in occupational settings is associated with alterations in Th17 cells, which may further predispose an individual to other systemic abnormalities.

A double-edged sword: Role of butyrate in the oral cavity and the gut

Butyrate, a four-carbon short-chain fatty acid (SCFA), is a metabolite of anaerobic bacteria. Butyrate has primarily been described as an energy substance in the studies on the digestive tract. The multiple mechanisms of its protective function in the gut and on underlying diseases (including metabolic diseases, diseases of the nervous system, and osteoporosis) via interaction with intestinal epithelial cells and immune cells have been well documented. There are many butyrogenic bacteria in the oral cavity as well. As essential components of the oral microbiome, periodontal pathogens are also able to generate butyrate when undergoing metabolism. Considerable evidence has indicated that butyrate plays an essential role in the initiation and perpetuation of periodontitis. However, butyrate is considered to participate in the pro-inflammatory activities in periodontal tissue and the reactivation of latent viruses. In this review, we focused on the production and biological impact of butyrate in both intestine and oral cavity and explained the possible pathway of various diseases that were engaged by butyrate. Finally, we suggested two hypotheses, which may give a better understanding of the significantly different functions of butyrate in different organs (i.e., the expanded butyrate paradox).

Th17/Treg cells imbalance and their related cytokines (IL-17, IL-10 and TGF-β) in children with autism spectrum disorder

We aimed in this study to investigate a possible involvement of Th17/Treg cells imbalance in autism spectrum disorders (ASD). Using flowcytometry to determine circulating Th17 and Treg cells percentages, RT- PCR and ELISA for cytokine expression, we demonstrated that Th17/Treg balance in ASD children was significantly skewed toward a Th17 response compared to their control. Th17 cells and the ratio of Th17/Treg cells had a significantly positive correlation with disease severity whereas Treg cells had a negative correlation. The imbalance of Th17, Treg cells and their related cytokines may play a vital role in the progression of the disease.

Fatty Liver Disease Caused by High-Alcohol-Producing Klebsiella pneumoniae

The underlying etiology of nonalcoholic fatty liver disease (NAFLD) is believed to be quite varied. Changes in the gut microbiota have been investigated and are believed to contribute to at least some cases of the disease, though a causal relationship remains unclear. Here, we show that high-alcohol-producing Klebsiella pneumoniae (HiAlc Kpn) is associated with up to 60% of individuals with NAFLD in a Chinese cohort. Transfer of clinical isolates of HiAlc Kpn by oral gavage into mice induced NAFLD. Likewise, fecal microbiota transplant (FMT) into mice using a HiAlc-Kpn-strain-containing microbiota isolated from an individual with NASH induced NAFLD. However, selective elimination of the HiAlc Kpn strain before FMT prevented NAFLD in the recipient mice. These results suggest that at least in some cases of NAFLD an alteration in the gut microbiome drives the condition due to excess endogenous alcohol production.

Moderate physical exercise improves lymphocyte function in melanoma-bearing mice on a high-fat diet

Background

Obesity can lead to a chronic systemic inflammatory state that increases the risk of cancer development. Therefore, this study aimed to evaluate the alterations in tumor non-infiltrated lymphocytes function and melanoma growth in animals maintained on a high-fat diet and/or moderate physical exercise program in a murine model of melanoma.

Methods

Female mice were randomly divided into eight groups: 1) normolipidic control (N), 2) normolipidic + melanoma (NM), 3) high-fat control (H), 4) high-fat + melanoma (HM), 5) normolipidic control + physical exercise (NE), 6) normolipidic melanoma + physical exercise (NEM), 7) high-fat control + physical exercise (HE), and 8) high-fat melanoma + physical exercise (HEM). After 8 weeks of diet treatment and/or moderate physical exercise protocol, melanoma was initiated by explanting B16F10 cells into one-half of the animals.

Results

Animals fed a high-fat diet presented high-energy consumption (30%) and body weight gain (H and HE vs N and NE, 37%; HM and HEM vs NM and NEM, 73%, respectively), whether or not they carried melanoma explants. Although the tumor growth rate was higher in animals from the HM group than in animals from any other sedentary group, it was reduced by the addition of a physical exercise regimen. We also observed an increase in stimulated peripheral lymphocyte proliferation and a decrease in the T-helper 1 response in the HEM group.

Conclusions

The results of the present study support the hypothesis that altering function of tumor non-infiltrated lymphocytes via exercise-related mechanisms can slow melanoma progression, indicating that the incorporation of a regular practice of moderate-intensity exercises can be a potential strategy for current therapeutic regimens in treating advanced melanoma.

IL-17A, MCP-1, CCR-2, and ABCA1 polymorphisms in children with non-alcoholic fatty liver disease

OBJECTIVE

The prevalence of non-alcoholic fatty liver disease in children has risen significantly, owing to the worldwide childhood obesity epidemic in the last two decades. Non-alcoholic fatty liver disease is closely linked to sedentary lifestyle, increased body mass index, and visceral adiposity. In addition, individual genetic variations also have a role in the development and progression of non-alcoholic fatty liver disease. The aim of this study was to investigate the gene polymorphisms of MCP-1 (-2518 A/G) (rs1024611), CCR-2 (190 G/A) (rs1799864), ABCA1 (883 G/A) (rs4149313), and IL-17A (-197 G/A) (rs2275913) in obese Turkish children with non-alcoholic fatty liver disease.

METHODS

The study recruited 186 obese children aged 10-17 years, including 101 children with non-alcoholic fatty liver disease and 85 children without non-alcoholic fatty liver disease. Anthropometric measurements, insulin resistance, a liver panel, a lipid profile, liver ultrasound examination, and genotyping of the four variants were performed.

RESULTS

No difference was found between the groups in respect to age and gender, body mass index, waist/hip ratio, or body fat ratio. In addition to the elevated ALT levels, AST and GGT levels were found significantly higher in the non-alcoholic fatty liver disease group compared to the non non-alcoholic fatty liver disease group (p<0.05). The A-allele of IL-17A (-197 G/A) (rs2275913) was associated with non-alcoholic fatty liver disease (odds ratio [OR] 2.05, 95% confidence interval: 1.12-3.77, p=0.02).

CONCLUSIONS

The findings of this study suggest that there may be an association between IL-17A (-197 G/A) (rs2275913) polymorphism and non-alcoholic fatty liver disease development in obese Turkish children.

The Differential Roles of T Cells in Non-alcoholic Fatty Liver Disease and Obesity

Non-alcoholic fatty liver disease (NAFLD) constitutes a spectrum of disease states characterized by hepatic steatosis and is closely associated to obesity and the metabolic syndrome. In non-alcoholic steatohepatitis (NASH), additionally, inflammatory changes and hepatocellular damage are present, representing a more severe condition, for which the treatment is an unmet medical need. Pathophysiologically, the immune system is one of the main drivers of NAFLD progression and other obesity-related comorbidities, and both the innate and adaptive immune system are involved. T cells form the cellular component of the adaptive immune system and consist of multiple differentially active subsets, i.e., T helper (Th) cells, regulatory T (Treg) cells, and cytotoxic T (Tc) cells, as well as several innate T-cell subsets. This review focuses on the role of these T-cell subsets in the pathogenesis of NAFLD, as well as the association with obesity and type 2 diabetes mellitus, reviewing the available evidence from both animal and human studies. Briefly, Th1, Th2, Th17, and Th22 cells seem to have an attenuating effect on adiposity. Th2, Th22, and Treg cells seem to decrease insulin resistance, whereas Th1, Th17, and Tc cells have an aggravating effect. Concerning NAFLD, both Th22 and Treg cells appear to have an overall tempering effect, whereas Th17 and Tc cells seem to induce more liver damage and fibrosis progression. The evidence regarding the role of the innate T-cell subsets is more controversial and warrants further exploration.

High fiber dietary and sodium butyrate attenuate experimental autoimmune hepatitis through regulation of immune regulatory cells and intestinal barrier

Autoimmune hepatitis (AIH) is chronic autoimmune liver disease accompanied with the imbalance of Treg/Th17 and increased intestinal permeability. We investigated the effects of a high fiber diet and sodium butyrate on the Treg/Th17 and intestinal barrier function in an experimental autoimmune hepatitis. Intraperitoneal injection of hepatic antigen (S100) was used to induce experimental autoimmune hepatitis mice model and mice were divided into normal control, S100 model control, S100 plus high fiber diet and S100 plus sodium butyrate. Serum aminotransferases and liver histology were examined. Short chain fatty acids in feces were determined by HPLC. The ratio of CD4 + C25 + Foxp3+ Treg and CD4 + IL-17 + Th17 were evaluated by flow cytometry. Tight junction proteins Zonula ocluden, Occludin and Claudin-1 were used to assess intestinal barrier function, so does Escherichia coli protein in the liver. Mice fed with either high fiber diet or sodium butyrate showed significantly lower levers of serum aminotransferases and minor liver injury compared to that of model control. Moreover, the ratio of Treg/Th17 was significantly higher in high fiber diet and sodium butyrate fed mice than that in model control. Furthermore, high fiber diet and sodium butyrate significantly increased intestinal tight junction proteins and decreased Escherichia Coli protein in the liver. In conclusion, high fiber diet and sodium butyrate can attenuate development of autoimmune hepatitis through regulation of immune regulatory cells and intestinal barrier function.

Immunity and Fibrogenesis: The Role of Th17/IL-17 Axis in HBV and HCV-induced Chronic Hepatitis and Progression to Cirrhosis

Cirrhosis is a common final pathway for most chronic liver diseases; representing an increasing burden worldwide and is associated with increased morbidity and mortality. Current evidence has shown that, after an initial injury, the immune response has a significant participation in the ongoing damage, and progression from chronic viral hepatitis (CVH) to cirrhosis, driving the activation and maintenance of main fibrogenic pathways. Among immune deregulations, those related to the subtype 17 of T helper lymphocytes (Th17)/interleukin-17 (IL-17) axis have been recognized as key immunopathological and prognostic elements in patients with CVH. The Th17/IL-17 axis has been found involved in several points of fibrogenesis chain from the activation of stellate cells, increased expression of profibrotic factors as TGF-β, promotion of the myofibroblastic or epithelial–mesenchymal transition, stimulation of the synthesis of collagen, and induction of imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). It also promotes the recruitment of inflammatory cells and increases the expression of proinflammatory cytokines such as IL-6 and IL-23. So, the Th17/IL-17 axis is simultaneously the fuel and the flame of a sustained proinflammatory and profibrotic environment. This work aims to present the immunopathologic and prognostic role of the Th17/IL-17 axis and related pathways in fibrogenesis and progression to cirrhosis in patients with liver disease due to hepatitis B virus (HBV) and hepatitis C virus (HCV).

The imbalance of Th17/Treg cells is involved in the progression of nonalcoholic fatty liver disease in mice

Background

Non-alcoholic fatty liver disease (NAFLD) is a common, chronic liver disease worldwide. Recent studies have shown that T helper (Th) 17 and regulatory T (Treg) cells play critical roles in various disorders of liver inflammation. Here, we explored the value of polyene phosphatidylcholine capsules (PPC) for regulating the imbalance of Th17/Treg cells in the pathogenesis of mice with NAFLD.

Methods

C57BL/6 mice were randomly divided into three groups as follows:normal diet (ND), high-fat diet (HF),and HF plus PPC(HF + PPC). The frequencies of splenic Th17 and Treg cells were measured by flow cytometry, and their related cytokines were analyzed by CBA and real-time PCR.

Results

At the end of 24 weeks, mice in the HF group had a higher frequency of intrahepatic Th17 cells,and a lower proportion of Treg cells compared with the ND group. The levels of Th17 cell-related cytokines (IL-6, IL-17 and IL-23) in serum and in liver tisse were increased,and the hepatic mRNA levels of RORγt, STAT3 and IL-6 were also increased. By contrast,the FoxP3 mRNA level was decreased in the HF group. Moreover, significant pathological and biochemical changes in the liver, as well as serum biochemical changes, were found in mice with NAFLD. Interestingly, following treatment with PPC, the levels of liver inflammation,frequencies of Th17/Treg cells and associated cytokines,and biochemical data were significantly altered.

Conclusion

These findings demonstrate a critical role for PPC in partially attenuating liver inflammatory responses in mice with NAFLD that involves the imbalance of Treg/Th17 cells and associated cytokines.

High serum resistin associates with intrahepatic inflammation and necrosis: an index of disease severity for patients with chronic HBV infection

BACKGROUND

Studies have revealed that resistin plays a role as an intrahepatic cytokine with proinflammatory activities. This study investigated the association between serum resistin and fibrosis severity and the possible marker role of resistin in the inflammatory process of chronic hepatitis B.

METHODS

In this study, 234 subjects with HBV infection were retrospectively selected, including 85 patients with chronic hepatitis B (CHB), 70 patients with HBV-related liver cirrhosis (LC-B), and 79 patients with HBV-related liver failure (LF-B). Serum levels of resistin, IL-1, IL-6, IL-17, IL-23, TNF-α, and TGF-β1 were assayed by ELISA. Demographic and clinical characteristics of patients were extracted from clinical databases of Taihe Hospital, Hubei University of Medicine, including serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBil), and liver stiffness (LS).

RESULTS

All the selected patients with HBV infection showed significantly increased levels of serum resistin, which was rarely detectable in the healthy controls. Serum resistin levels in patients with CHB, LC-B, and LF-B were 4.119 ± 5.848 ng/mL, 6.370 ± 6.834 ng/mL, and 6.512 ± 6.076 ng/mL, respectively. Compared with the CHB group, patients with LC-B or LF-B presented with significantly higher serum levels of resistin (p < 0.01). On the other hand, all of the enrolled patients had high serum levels of IL-1, IL-6, IL-17, TNF-α, and TGF-β1, but not IL-23. Interestingly, serum levels of resistin was significantly positively correlated with serum levels of TGF-β1 in LC-B patients (R = 0.3090, p = 0.0290), with IL-17 in LC-B (R = 0.4022, p = 0.0038) and LF-B patients (R = 0.5466, p < 0.0001), and with AST (R = 0.4501, p = 0.0036) and LS (R = 0.3415, p = 0.0310) in CHB patients.

CONCLUSIONS

High serum resistin associates with intrahepatic inflammation and necrosis and may be used as an index of disease severity for patients with chronic HBV infection.

Modulation of liver tolerance by conventional and nonconventional antigen-presenting cells and regulatory immune cells

The liver is a tolerogenic organ with exquisite mechanisms of immune regulation that ensure upkeep of local and systemic immune tolerance to self and foreign antigens, but that is also able to mount effective immune responses against pathogens. The immune privilege of liver allografts was recognized first in pigs in spite of major histo-compatibility complex mismatch, and termed the "liver tolerance effect". Furthermore, liver transplants are spontaneously accepted with only low-dose immunosuppression, and induce tolerance for non-hepatic co-transplanted allografts of the same donor. Although this immunotolerogenic environment is favorable in the setting of organ transplantation, it is detrimental in chronic infectious liver diseases like hepatitis B or C, malaria, schistosomiasis or tumorigenesis, leading to pathogen persistence and weak anti-tumor effects. The liver is a primary site of T-cell activation, but it elicits poor or incomplete activation of T cells, leading to their abortive activation, exhaustion, suppression of their effector function and early death. This is exploited by pathogens and can impair pathogen control and clearance or allow tumor growth. Hepatic priming of T cells is mediated by a number of local conventional and nonconventional antigen-presenting cells (APCs), which promote tolerance by immune deviation, induction of T-cell anergy or apoptosis, and generating and expanding regulatory T cells. This review will focus on the communication between classical and nonclassical APCs and lymphocytes in the liver in tolerance induction and will discuss recent insights into the role of innate lymphocytes in this process.

Immune Cells and Metabolism

Low-grade inflammation in the obese AT (AT) and the liver is a critical player in the development of obesity-related metabolic dysregulation, including insulin resistance, type 2 diabetes and non-alcoholic steatohepatitis (NASH). Myeloid as well as lymphoid cells infiltrate the AT and the liver and expand within these metabolic organs as a result of excessive nutrient intake, thereby exacerbating tissue inflammation. Macrophages are the paramount cell population in the field of metabolism-related inflammation; as obesity progresses, a switch takes place within the AT environment from an M2-alternatively activated macrophage state to an M1-inflammatory macrophage-dominated milieu. M1-polarized macrophages secrete inflammatory cytokines like TNF in the obese AT; such cytokines contribute to insulin resistance in adipocytes. Besides macrophages, also CD8+ T cells promote inflammation in the AT and the liver and thereby the deterioration of the metabolic balance in adipocytes and hepatocytes. Other cells of the innate immunity, such as neutrophils or mast cells, interfere with metabolic homeostasis as well. On the other hand, eosinophils or T-regulatory cells, the number of which in the AT decreases in the course of obesity, function to maintain metabolic balance by ameliorating inflammatory processes. In addition, eosinophils and M2-polarized macrophages may contribute to "beige" adipogenesis under lean conditions; beige adipocytes are located predominantly in the subcutaneous AT and have thermogenic and optimal energy-dispensing properties like brown adipocytes. This chapter will summarize the different aspects of the regulation of homeostasis of metabolic tissues by immune cells.

Role of interleukin 17 in fatty liver disease and other liver diseases

Fatty liver disease is a lipid metabolism disorder in the liver, with a variety of etiologies which result in the accumulation of fat in the liver. The pathogenesis of fatty liver disease is still unclear and symptomatic treatment is the main method. In recent years, the incidence of fatty liver disease in China is increasing year by year, and the age of onset becomes younger. Recent studies suggest that interleukin 17 (IL-17) is involved not only in the pathogenesis of various diseases, such as autoimmune diseases, inflammatory diseases, and malignant tumors, but also in fatty liver and other liver diseases through inducing insulin resistance, activating some important pathways in the liver, mediating some inflammatory factors and so on. This paper will review the role of IL-17 in fatty liver disease and other liver diseases.

Dendritic Cells Regulate Treg-Th17 Axis in Obstructive Phase of Bile Duct Injury in Murine Biliary Atresia

Several cell types are considered to be effector cells in bile duct injury in rhesus rotavirus (RRV)-induced experimental biliary atresia (BA). Here, we identified an increased T helper 17 (Th17) cell population in a BA mode. By depleting the Th17 cells, the BA symptoms (onset of jaundice, acholic stools and retarded growth) were attenuated and the survival rate was improved. Furthermore, we found that in mice with BA, the percentage of CD4⁺CD25^highFoxp3⁺ T regulatory (Treg) cells decreased along with the increased percentage of Th17 cells. However, the absolute numbers of Treg and Th17 cells were both increased in liver of RRV-injected mice compared to saline-injected mice. The proportion of Th17 cells at 7 days post-infection was decreased if Treg cells isolated from normal adult mice, but not Treg cells from the livers of mice with BA, were intraperitoneally transferred on day 5 of life. In vitro experiments also showed that Treg cells from mice with BA had a diminished suppressive effect on Th17 cell generation. To determine the mechanisms, we investigated the production of cytokines in the liver. The level of IL-6, which has been shown to be abundantly secreted by activated dendritic cells (DCs), was remarkably elevated. Importantly, in a Treg/Th17 cell suppression assay, IL-6 was demonstrated to paralyze the Treg cells’ suppressive effect on Th17 cells and eventually the unrestrained increase of Th17 cells contributed to bile duct injury. In conclusion, the DC-regulated Treg-Th17 axis, probably in conjunction with other effector T cells, aggravates progressive inflammatory injury at the time of ductal obstruction.

The Human Mesenchymal Stromal Cell-Derived Osteocyte Capacity to Modulate Dendritic Cell Functions Is Strictly Dependent on the Culture System

In vitro differentiation of mesenchymal stromal cells (MSC) into osteocytes (human differentiated osteogenic cells, hDOC) before implantation has been proposed to optimize bone regeneration. However, a deep characterization of the immunological properties of DOC, including their effect on dendritic cell (DC) function, is not available. DOC can be used either as cellular suspension (detached, Det-DOC) or as adherent cells implanted on scaffolds (adherent, Adh-DOC). By mimicking in vitro these two different routes of administration, we show that both Det-DOC and Adh-DOC can modulate DC functions. Specifically, the weak downregulation of CD80 and CD86 caused by Det-DOC on DC surface results in a weak modulation of DC functions, which indeed retain a high capacity to induce T-cell proliferation and to generate CD4⁺CD25⁺Foxp3⁺ T cells. Moreover, Det-DOC enhance the DC capacity to differentiate CD4⁺CD161⁺CD196⁺ Th17-cells by upregulating IL-6 secretion. Conversely, Adh-DOC strongly suppress DC functions by a profound downregulation of CD80 and CD86 on DC as well as by the inhibition of TGF-β production. In conclusion, we demonstrate that different types of DOC cell preparation may have a different impact on the modulation of the host immune system. This finding may have relevant implications for the design of cell-based tissue-engineering strategies.

Autoimmune hepatitis: recent advances in the pathogenesis and new diagnostic guidelines in Japan

Autoimmune hepatitis (AIH) is thought to be associated with various genetic and immunological abnormalities. Concerning the pathogenesis of AIH, increasing attention has been paid to genome-wide association studies, toll-like receptors and Treg/Th17 balance. For Japanese patients with AIH, novel diagnostic guidelines have been proposed in view of the differential clinical features between Japanese and Caucasian patients. However, the diagnosis of some patients in acute hepatitis phase is not easy. Histologically, centrilobular necrosis without portal inflammation is particularly characteristic in the acute hepatitis phase. Some patients become resistant to steroid therapy and have a very poor prognosis once they progress to acute hepatic failure. Therefore, additional revision of the current diagnostic criteria, including severity grading, will be needed in the future.

Randomized trial of autologous bone marrow mesenchymal stem cells transplantation for hepatitis B virus cirrhosis: regulation of Treg/Th17 cells

BACKGROUND AND AIM

Liver cirrhosis is one of the major consequences of hepatitis B virus (HBV) infection, and transplantation of autologous bone marrow mesenchymal stem cells (ABMSCs) is one of promising therapies for patients with HBV-related liver cirrhosis (HBV-LC). However, the mechanism is unclear. The aim of the current study was to explore the role of Treg/Th17 cells in ABMSCs transplantation in patients with HBV-LC.

METHODS

In this prospective study, 56 patients were enrolled and randomly assigned to transplantation group and control group. After 24-week follow-up, 39 patients completed the study (20 cases in transplantation group and 19 cases in control group). The Model for End-Stage Liver Disease scores, liver function, changes of Treg/Th17 cells, as well as related transcription factors and serum cytokines, were determined.

RESULTS

Although patients in both groups showed significant improvement after Entecavir treatment, ABMSC transplantation further improved patients' liver function. Moreover, there was a significant increase in Treg cells and a marked decrease in Th17 cells in the transplantation group compared with control, leading to an increased Treg/Th17 ratio. Furthermore, mRNA levels of Treg-related transcription factor (Foxp3) and Th17-related transcription factor (RORγt) were increased and decreased, respectively. In addition, serum transforming growth factor-β levels were significantly higher at early weeks of transplantation, while serum levels of interleukin-17, tumor necrosis factor-α, and interleukin-6 were significantly lower in patients in the transplantation group compared with control.

CONCLUSION

ABMSCs transplantation was effective in improving liver function in patients with HBV-LC, which was mediated, at least in part, through the regulation of Treg/Th17 cell balance.

The effect of antifibrotic drug halofugine on Th17 cells in concanavalin A-induced liver fibrosis

Anti-inflammation strategy is one of the proposed therapeutic approaches to hepatic fibrosis. T helper (Th) 17 cells, which play a detrimental role in experimental murine models of inflammatory diseases, have been demonstrated to participate in the pathogenesis of liver damage. The inhibitory effect of halofuginone (HF), an active component of extracts derived from the plant alkaloid febrifugine, on collagen synthesis has been shown in animal models of the fibrotic disease. The aim of this study was to clarify the in vivo effect of HF on Th17 cells in concanavalin A-induced fibrosis rats. Haematoxylin-eosin (HE) staining and Masson staining were performed to observe collagen deposition. The presence of INF-gamma, TNF-alpha, IL-6, IL-17, IL-1beta, IL-33 and IL-10 in serum and the presence of ROR-γt, IL-17, TGF-β1 and α-SMA in liver tissue were detected. Flow cytometry was performed to analyse the percentage of Th17 cells. We observed significantly lower levels of INF-gamma, TNF-alpha, IL-6, IL-17, IL-1beta, TGF-β1 and α-SMA in HF-treated group of rats, and the percentage of Th17 cells in splenic lymphocyte was decreased well. Histological examination demonstrated that HF significantly reduced the severity of liver fibrosis in HF-treated rats. We concluded that HF (10 mg/kg) exerts an antifibrotic impact on Th17 cells and its relative cytokines in rats with ConA-induced fibrosis.

Impaired balance of T helper 17/T regulatory cells in carbon tetrachloride-induced liver fibrosis in mice

AIM: To investigate the effect of T helper (Th) 17/T regulatory (Treg) cells on hepatic fibrosis in mice and its possible mechanism.

METHODS: Hepatic fibrosis was induced by intraperitoneal injection of carbon tetrachloride. Hepatic pathological changes were observed by hematoxylin and eosin staining; the protein levels of interleukin (IL)-6, transforming growth factor (TGF)-β and α-smooth muscle actin (SMA) in liver tissue were determined by Western blotting; and the frequency of Th17 and Treg cells in the liver was estimated by flow cytometry. In addition, hepatic stellate cells were isolated from healthy mouse liver and co-cultured with Th17 or Treg cells. Immunofluorescence staining and Western blotting were performed to determine the change in HSC activation.

RESULTS: In the model group, there were different degrees of fibroplasia, degeneration and necrosis. The protein levels of IL-6, TGF-β and α-SMA in liver tissue were significantly higher than those in the control group at 12 wk (P < 0.05). Compared with the control group, the frequency of Th17 cells in the model group was increased but the frequency of Treg cells decreased gradually. Furthermore, at 4, 8 and 12 wk, there were significant differences in the number of Th17 cells (0.52% ± 0.16%, 1.46% ± 0.24%, and 2.60% ± 0.41%, respectively, P < 0.05) and Treg cells (2.99% ± 0.40%, 2.16% ± 0.50%, and 1.49% ± 0.34%, respectively, P < 0.05). In vitro, Th17 cells promoted, whereas Treg cells inhibited the expression of α-SMA, both in a dose-dependent manner, compared with the control group.

CONCLUSION: Th17/Treg imbalance exists in mice with liver fibrosis, which potentially promotes liver fibrosis via HSC activation.

Th17/Treg imbalance in triptolide-induced liver injury

The study was designed to investigate the immune-modulatory effects of triptolide (TP) on CD4(+) T cell responses during liver injury. Previous studies have suggested that TP plays a critical role in modulating both innate and adaptive immune reactions, but its effects on the Th17/Treg balance during TP-induced liver injury remain unknown. In this study, female C57BL/6 mice were administered by oral gavage with TP at a dose of 250 or 500 μg/kg per mouse. We examined the plasma biochemical parameters, histopathological changes, hepatic frequencies of Th17 cells and Treg cells, hepatic expression of transcriptional factors and cytokine genes and hepatic interleukin (IL)-17 and IL-10 levels in TP-administered mice. Mice treated with TP displayed liver injury with markedly increased plasma transaminase as well as hepatic mRNA expression of retinoid related orphan receptor (ROR)-γt and hepatic IL-17 level at 24h. However, hepatic frequencies of Tregs and hepatic expression of forkhead/winged-helix family transcriptional repressor p3 (FoxP3) decreased at 24h after TP administration. Furthermore, we found that elevated serum biochemical parameters positively correlated with the Th17/Treg ratios. Taken together, these results revealed a novel and interesting phenomenon of TP in the enhancement of the expansion of Th17 cells and suppression of the production of Tregs during liver injury, which may represent a new pathogenesis of TP-induced liver injury.

T helper 17 cells in autoimmune liver diseases

Many autoimmune diseases are driven by self-reactive T helper (Th) cells. A new population of effector CD4⁺ T cells characterized by the secretion of interleukin (IL)-17, referred to as Th17 cells, has been demonstrated to be phenotypically, functionally, and developmentally distinct from Th1 and Th2 cells. Because the liver is known to be an important source of transforming growth factor-β and IL-6, which are cytokines that are crucial for Th17 differentiation, it is very likely that Th17 cells contribute to liver inflammation and autoimmunity. In contrast, another distinct subset of T cells, regulatory T cells (Treg), downregulate immune responses and play an important role in maintaining self-tolerance. In addition, there is a reciprocal relationship between Th17 cells and Tregs, in development and effector functions, and the balance between Th17 and Treg cells can affect the outcome of immune responses, particularly in autoimmune diseases. In this review, we will focus on the latest investigative findings related to Th17 cells in autoimmune liver disease.

Immunological mechanisms in the pathophysiology of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by the presence of steatosis, inflammation and hepatocyte injury and constitutes hepatic manifestation of the metabolic syndrome. The pathogenesis of NASH is complex and implicates cross-talk between different metabolically active sites, such as liver and adipose tissue. Obesity is considered a chronic low-grade inflammatory state and the liver has been recognized as being an "immunological organ". The complex role of the immune system in the pathogenesis of NASH is currently raising great interest, also in view of the possible therapeutic potential of immunotherapy in NASH. This review focuses on the disturbances of the cells constituting the innate and adaptive immune system in the liver and in adipose tissue.

Neutralization of interleukin-17 attenuates high fat diet-induced non-alcoholic fatty liver disease in mice

Non-alcoholic fatty liver disease (NAFLD) is hepatic manifestation of a metabolic syndrome and includes a spectrum of hepatic steatosis, steatohepatitis, and fibrosis. Interleukin-17 (IL-17) has been reported to play a critical role in inflammatory progression of some liver diseases. The present study was designed to investigate the role of IL-17 on high fat diet-induced NAFLD in C57BL/6 mice. IL-17 blockade with anti-IL-17mAb significantly improved liver function, attenuated hepatic lipid accumulation, suppressed Kuffer cells activation, and decreased pro-inflammatory cytokines levels, which were associated with inhibition of NF-κB signaling cascades activation. Our data suggested that IL-17 was related to disease progression in NAFLD mouse model and blocking IL-17 may be a promising novel therapeutic approach for patients with NAFLD.

Immune and inflammatory pathways in NASH

Immune and inflammatory pathways have a central role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Both the innate and adaptive immune systems contribute to the development of NAFLD. Pathogen-associated molecular patterns and danger-associated molecular patterns are known to activate a variety of pattern-recognition receptors that result in inflammation. The key features of the immune system and inflammatory pathways in the development of NAFLD are discussed in this review.

[Role of T lymphocyte cyclic nucleotides and G protein in sarcoidosis]

CD4+ T lymphocytes play a major role in the pathophysiology of sarcoidosis. Many studies have investigated the immunological and genetic abnormalities in this disease. There are few studies concerning the metabolic pathways. Essentially they concern the pathways: STAT1, MAPK38, NF-κB, Galphai, cAMP and cGMP PDE and PEMT1. Using studies in the literature and results of our own work concerning some metabolic aspects of T lymphocytes in sarcoidosis, we present a revue of the various hypotheses, which involve dysfunction of cAMP signaling pathways, such as RAS/RAF/MEK/ERK in T lymphocytes, leading to a disorder of immunity.

Biliary obstruction results in PD-1-dependent liver T cell dysfunction and acute inflammation mediated by Th17 cells and neutrophils

Biliary obstruction is a common clinical problem that is associated with intrahepatic inflammation and impaired immunity. PD-1 is well known to mediate T cell dysfunction but has been reported to promote and attenuate acute inflammation in various injury models. With the use of a well-established murine model of BDL, we studied the effects of intrahepatic PD-1 expression on LTC function, inflammation, and cholestasis. Following BDL, PD-1 expression increased significantly among LTCs. Increased PD-1 expression following BDL was associated with decreased LTC proliferation and less IFN-γ production. Elimination of PD-1 expression resulted in significantly improved proliferative capacity among LTC following BDL, in addition to a more immunostimulatory cytokine profile. Not only was LTC function rescued in PD-1(-/-) mice, but also, the degrees of biliary cell injury, cholestasis, and inflammation were diminished significantly compared with WT animals following BDL. PD-1-mediated acute inflammation following BDL was associated with expansions of intrahepatic neutrophil and Th17 cell populations, with the latter dependent on IL-6. PD-1 blockade represents an attractive strategy for reversing intrahepatic immunosuppression while limiting inflammatory liver damage.

Th17 cells and liver diseases

In recent years, it has been demonstrated that T helper cells 17 (Th17) are closely related to the occurrence and development of many kinds of liver diseases such as viral hepatitis, autoimmune liver diseases and fatty liver diseases. Th17 cells are a new CD4⁺ T cell subset, which can interact with Th1, Th2 and Treg cells. There exists complex antagonistic or collaborative relationship among these cells. Understanding the role of Th17 cells in liver diseases will help explore the pathogenesis and treatment of these diseases.

The imbalance of T helper 17/regulatory T cells and memory B cells during the early post-transplantation period in peripheral blood of living donor liver transplantation recipients under calcineurin inhibitor-based immunosuppression

There is limited clinical research regarding the changes in peripheral lymphocyte subsets during the early post-operative period of liver transplantation. Serial changes of T cells and B cells in living donor liver transplantation (LDLT) recipients during the early post-transplantion period were prospectively investigated. From June 2010 to February 2011, 27 consecutive LDLT recipients were enrolled. Percentages of T helper type 1 (Th1; interferon-γ-producing), Th2 (interleukin-4-producing), Th17 (interleukin-17-producing), regulatory T (Treg; CD4(+) CD25(+) FoxP3(+) ), memory B (CD19(+) CD24(hi) CD38(-) ) and mature B (CD19(+) CD24(int) CD38(int) ) cells were measured using fluorescence-activated cell sorting. Patients were followed up for a median of 9.9 months (range 6.8-15.5 months) after transplantation. Serial monitoring of immunological profiles showed no significant suppression of Th1, Th2, Th17, mature B or memory B cells, whereas frequencies of Treg cells significantly decreased. Interleukin-17 production by central and effector memory cells was not suppressed during the early post-operative period. The continuous production of interleukin-17 by the memory T cells may contribute to the persistence of Th17 cells. This prospective study demonstrated that current immunosuppression maintained the effector T or memory B cells during the early post-transplantation period but significantly suppressed Treg cells. Serial immune monitoring may suggest clues for optimal or individualized immunosuppression during the early post-operative period in clinical practice.

CD4⁺ and CD8⁺ regulatory T cells (Tregs) are elevated and display an active phenotype in patients with chronic HCV mono-infection and HIV/HCV co-infection

The aim of this study was to examine regulatory T cells (Tregs) in peripheral blood and liver tissue in patients with chronic hepatitis C virus (HCV) mono-infection and in patients with HIV/HCV co-infection. In a cross-sectional study were included 51 patients with chronic HCV infection, 24 patients with HIV/HCV co-infection and 24 healthy individuals. CD4⁺ and CD8⁺ Tregs were determined using flow cytometry. Fibrosis was examined by transient elastography. Inflammation, fibrosis and Tregs were determined in liver biopsies from 12 patients. Increased frequency of CD4⁺ and CD8⁺ Tregs was found in HIV/HCV co-infected patients [median: 6.4% (IQR: 5.7-6.9) and 1.0% (0.7-1.2), respectively] compared to HCV mono-infected patients [5.6% (4.2-6.3), P = 0.01 and 0.5% (0.3-0.7), P < 0.001, respectively]. Furthermore, HCV mono-infected patients had increased frequencies of Tregs compared with healthy controls (P < 0.05). However, no associations between the frequency of Tregs and fibrosis were found. Furthermore, characterization of CD4⁺ Tregs using CD45RA demonstrated a higher frequency of activated Tregs in both HCV mono-infected and HIV/HCV co-infected patients compared with healthy controls. Finally, number of intrahepatic Tregs was associated with both peripheral CD8⁺ Tregs and intrahepatic inflammation. In conclusion, HCV mono-infected patients and particularly HIV/HCV co-infected patients have increased the frequency of CD4⁺ and CD8⁺ Tregs compared with healthy controls. Furthermore, CD4⁺ Tregs in infected patients displayed an active phenotype. Tregs were not associated with fibrosis, but a positive correlation between intrahepatic Tregs and inflammation was found. Taken together, these results suggest a role for Tregs in the pathogenesis of chronic HCV infection.

Mathematical models of e-antigen mediated immune tolerance and activation following prenatal HBV infection

We develop mathematical models for the role of hepatitis B e-antigen in creating immunological tolerance during hepatitis B virus infection and propose mechanisms for hepatitis B e-antigen clearance, subsequent emergence of a potent cellular immune response, and the effect of these on liver damage. We investigate the dynamics of virus-immune cells interactions, and derive parameter regimes that allow for viral persistence. We modify the model to account for mechanisms responsible for hepatitis B e-antigen loss, such as seroconversion and virus mutations that lead to emergence of cellular immune response to the mutant virus. Our models demonstrate that either seroconversion or mutations can induce immune activation and that instantaneous loss of e-antigen by either mechanism is associated with least liver damage and is therefore more beneficial for disease outcomes.

T cell immunopathogenesis and immunotherapeutic strategies for chronic hepatitis B virus infection

Hepatitis B is caused by the host immune response and T cells play a major role in the immunopathogenesis. More importantly, T cells not only destroy hepatocytes infected by hepatitis B virus (HBV), but also control HBV replication or eradicate HBV in a noncytolytic manner. Therefore, analysis of T cell immune response during acute and chronic HBV infection is important to develop a strategy for successful viral control, which could lead to immunotherapy for terminating persistent HBV infection. There have been many attempts at immunotherapy for chronic HBV infection, and some have shown promising results. High viral load has been shown to suppress antiviral immune responses and immunoinhibitory signals have been recently elucidated, therefore, viral suppression by nucleos(t)ide analogs, stimulation of antiviral immune response, and suppression of the immunoinhibitory signals must be combined to achieve desirable antiviral effects.

Increased muscle expression of interleukin-17 in Duchenne muscular dystrophy

OBJECTIVES

Duchenne muscular dystrophy (DMD) is a degenerative muscle wasting disease caused by mutations in the dystrophin gene. Dystrophic muscle is characterized by chronic inflammation, and inflammatory mediators could be promising targets for innovative therapeutic interventions. We analyzed muscle biopsy samples of DMD-affected children to characterize interleukin (IL)-17 and Forkhead box P3 (Foxp3) expression levels and to identify possible correlations with clinical status.

METHODS

Expression levels of IL-17, Foxp3, tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), IL-6, and transforming growth factor-β (TGF-β) were analyzed by real-time PCR in muscle biopsy samples from patients with DMD (n = 27) and juvenile dermatomyositis (JDM) (n = 8). Motor outcome of patients with DMD was evaluated by North Star Ambulatory Assessment score.

RESULTS

In DMD, we found higher levels of IL-17 and lower levels of Foxp3 mRNA compared with those for a typical inflammatory myopathy, JDM. Moreover, the IL-17/Foxp3 ratio was higher in DMD than in JDM biopsy samples. IL-17 mRNA levels appeared to be related to the expression levels of other proinflammatory cytokines (TNF-α and MCP-1) and significantly associated with clinical outcome of patients.

CONCLUSIONS

The association of IL-17 expression with levels of other inflammatory cytokines and with the clinical course of DMD suggests a possible pathogenic role of IL-17.

IL-17A-producing NK cells were implicated in liver injury induced by ischemia and reperfusion

NK cells play a critical role in several types of liver injury. The aim of this study was to evaluate the role of NK cells in liver ischemia reperfusion injury (IRI) and the underlying mechanism. Male Rag1-/- mice and wild type mice were subjected to partial hepatic IRI. Anti-NK1.1 (300 μg/mouse, ip) was used to deplete NK cells. Liver injury was evaluated by level of serum alanine aminotransferase (ALT). Hepatic inflammatory cytokines, neutrophils and CXCL-2 expression were measured following ischemia and reperfusion. Additionally, NK cells were cultured with or without IL-6, IL-21, IL-23 and IL-10 for 24h, then IL-17A level in the supernatants was analyzed by ELISA. Production of IL-17A was increased in NK cells after reperfusion. Various cytokines such as, IL-6, IL-21 and IL-23, which also elevated after IRI, can promote IL-17A production and up-regulate the phosphorylation of STAT3 in NK cells, while the increase was repressed in the presence of IL-10. Depletion of NK cells decreased IL-17A level in Rag1-/- mice ischemic lobes. Meanwhile, hepatic infiltration of neutrophils and CXCL-2 level were reduced and liver injury was ameliorated. Neutralization of IL-17A was used to confirm the role of this cytokine produced by NK cells in Rag1-/- mice. In conclusion, at initial stage of liver IRI, NK cells increase IL-17A production and promote liver injury.

Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease

Mechanisms associated with the progression of simple steatosis to non-alcoholic fatty liver disease (NAFLD) remain undefined. Regulatory T cells (T(regs)) play a critical role in regulating inflammatory processes in non-alcoholic steatohepatitis (NASH) and because T helper type 17 (Th17) functionally oppose T(reg)-mediated responses, this study focused on characterizing the role of Th17 cells using a NAFLD mouse model. C57BL/6 mice were fed either a normal diet (ND) or high fat (HF) diet for 8 weeks. Mice in the HF group had a significantly higher frequency of liver Th17 cells compared to ND-fed mice. Neutralization of interleukin (IL)-17 in HF mice ameliorated lipopolysaccharide (LPS)-induced liver injury reflected by decreased serum alanine aminotransferase (ALT) levels and reduced inflammatory cell infiltrates in the liver. In vitro, HepG2 cells cultured in the presence of free fatty acids (FFA; oleic acid and palmitic acid) for 24 h and IL-17 developed steatosis via insulin-signalling pathway interference. IL-17 and FFAs synergized to induce IL-6 production by HepG2 cells and murine primary hepatocytes which, in combination with transforming growth factor (TGF-β), expanded Th17 cells. It is likely that a similar process occurs in NASH patients, as there were significant levels of IL-17(+) cell infiltrates in NASH patient livers. The hepatic expression of Th17 cell-related genes [retinoid-related orphan receptor gamma (ROR)γt, IL-17, IL-21 and IL-23] was also increased significantly in NASH patients compared to healthy controls. Th17 cells and IL-17 were associated with hepatic steatosis and proinflammatory response in NAFLD and facilitated the transition from simple steatosis to steatohepatitis. Strategies designed to alter the balance between Th17 cells and T(regs) should be explored as a means of preventing progression to NASH and advanced liver diseases in NAFLD patients.