Hepatitis C viral infection is associated with activated cytolytic natural killer cells expressing high levels of T cell immunoglobulin- and mucin-domain-containing molecule-3

Beyond T cell exhaustion: TIM-3 regulation of myeloid cells

T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) is an important immune checkpoint molecule initially identified as a marker of IFN-γ-producing CD4+ and CD8+ T cells. Since then, our understanding of its role in immune responses has significantly expanded. Here, we review emerging evidence demonstrating unexpected roles for TIM-3 as a key regulator of myeloid cell function, in addition to recent work establishing TIM-3 as a delineator of terminal T cell exhaustion, thereby positioning TIM-3 at the interface between fatigued immune responses and reinvigoration. We share our perspective on the antagonism between TIM-3 and T cell stemness, discussing both cell-intrinsic and cell-extrinsic mechanisms underlying this relationship. Looking forward, we discuss approaches to decipher the underlying mechanisms by which TIM-3 regulates stemness, which has remarkable potential for the treatment of cancer, autoimmunity, and autoinflammation.

γδ T cells mediate robust anti-HIV functions during antiretroviral therapy regardless of immune checkpoint expression

Objectives

Although antiretroviral therapy (ART) efficiently suppresses HIV viral load, immune dysregulation and dysfunction persist in people living with HIV (PLWH). γδ T cells are functionally impaired during untreated HIV infection, but the extent to which they are reconstituted upon ART is currently unclear.

Methods

Utilising a cohort of ART-treated PLWH, we assessed the frequency and phenotype, characterised in vitro functional responses and defined the impact of immune checkpoint marker expression on effector functions of both Vδ1 and Vδ2 T cells. We additionally explore the in vitro expansion of Vδ2 T cells from PLWH on ART and the mechanisms by which such expanded cells may sense and kill HIV-infected targets.

Results

A matured NK cell-like phenotype was observed for Vδ1 T cells among 25 ART-treated individuals (PLWH/ART) studied compared to 17 HIV-uninfected controls, with heightened expression of 2B4, CD160, TIGIT and Tim-3. Despite persistent phenotypic perturbations, Vδ1 T cells from PLWH/ART exhibited strong CD16-mediated activation and degranulation, which were suppressed upon Tim-3 and TIGIT crosslinking. Vδ2 T cell degranulation responses to the phosphoantigen (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate at concentrations up to 2 ng mL-1 were significantly impaired in an immune checkpoint-independent manner among ART-treated participants. Nonetheless, expanded Vδ2 T cells from PLWH/ART retained potent anti-HIV effector functions, with the NKG2D receptor contributing substantially to the elimination of infected cells.

Conclusion

Our findings highlight that although significant perturbations remain within the γδ T cell compartment throughout ART-treated HIV, both subsets retain the capacity for robust anti-HIV effector functions.

Tim-3 Expression Causes NK Cell Dysfunction in Type 2 Diabetes Patients

Type 2 diabetes mellitus (T2DM) is characterized by high blood glucose levels and chronic low-grade inflammation. It shows a strong association with obesity and immune dysfunction, which makes T2DM patients more susceptible to infectious diseases. NK cells play an important role in pathogen control and tumor surveillance. However, whether NK cell distribution and functional status are altered in T2DM is unclear. To address this issue, we compared surface receptor expression and cytokine production between peripheral blood NK cells from 90 T2DM patients and 62 age- and sex-matched healthy controls. We found a significantly lower frequency and absolute number of NK cells in patients than in controls. Interestingly, the expression of inhibitory receptor Tim-3 was significantly increased, while the expression of the activating receptor NKG2D was significantly decreased, in T2DM NK cells. Both TNF-α secretion and degranulation capacity (evidenced by CD107a expression) were dampened in NK cells from patients. The expression of Tim-3 on NK cells correlated positively with both HbA1c and fasting blood glucose levels and negatively with the percentage and absolute number of total NK cells and was associated with increased NK cell apoptosis. In addition, Tim-3 expression on NK cells negatively correlated with TNF-α production, which could be restored by blocking Galectin-9/Tim-3 pathway. Our results suggest that NK cell dysfunction secondary to augmented Tim-3 expression occurs in T2DM patients, which may partly explain their increased susceptibility to cancer and infectious disease.

Inhibitory Receptors and Immune Checkpoints Regulating Natural Killer Cell Responses to Cancer

Simple Summary

Recent years marked the discovery and increased understanding of the role immune checkpoints play in immunity against cancer. This has revolutionized cancer treatment, saving the lives of many patients. For numerous years the spotlight of success has been directed towards T cells; however, it is now appreciated that other cells play vital roles in this protection. In this review we focused on cytotoxic lymphocytes Natural Killer (NK) cells, which are known to be well equipped in the fight against cancer. We explored the role of well-described and newly emerging inhibitory receptors, including immune checkpoints in regulating NK cell activity against cancer. The knowledge summarized in this review should guide the development of immunotherapies targeting inhibitory receptors with the aim of restoring NK cell responses in cancer patients.

Abstract

The discovery of immune checkpoints provided a breakthrough for cancer therapy. Immune checkpoints are inhibitory receptors that are up-regulated on chronically stimulated lymphocytes and have been shown to hinder immune responses to cancer. Monoclonal antibodies against the checkpoint molecules PD-1 and CTLA-4 have shown early clinical success against melanoma and are now approved to treat various cancers. Since then, the list of potential candidates for immune checkpoint blockade has dramatically increased. The current paradigm stipulates that immune checkpoint blockade therapy unleashes pre-existing T cell responses. However, there is accumulating evidence that some of these immune checkpoint molecules are also expressed on Natural Killer (NK) cells. In this review, we summarize our latest knowledge about targetable NK cell inhibitory receptors. We discuss the HLA-binding receptors KIRS and NKG2A, receptors binding to nectin and nectin-like molecules including TIGIT, CD96, and CD112R, and immune checkpoints commonly associated with T cells such as PD-1, TIM-3, and LAG-3. We also discuss newly discovered pathways such as IL-1R8 and often overlooked receptors such as CD161 and Siglecs. We detail how these inhibitory receptors might regulate NK cell responses to cancer, and, where relevant, we discuss their implications for therapeutic intervention.

PAX5 haploinsufficiency induced CD8+ T cells dysfunction or exhaustion by high expression of immune inhibitory-related molecules

PURPOSE

PAX5 haploinsufficiency promoting tumorigenesis is related to immune escape. But the mechanisms of PAX5 mutations inducing tumor immune escape have not been clarified. Our aim was to study how PAX5 haploinsufficiency influences effector CD8 + T cells in tumor microenvironment.

METHODS

We estimated the proportions of 22 immune cell types and the expressions of immune inhibitory-related molecules based on gene expression profiles (GEPs) from children's B- acute lymphoblastic leukemia(B-ALL) with PAX5 mutations by CIBERSORT, an established algorithm. We constructed the PAX5 haplodeletion A20 cell lines, built allografted A20 tumor models and evaluated the effect of PAX5 haplodeletion on immune inhibitory-related molecules in the tumor microenvironment (TME).

RESULTS

Our results indicated the percentages of T cells in bone marrow of children's B-ALL with PAX5 mutations were not statistically different from that in bone marrow of B-ALL without PAX5 mutations, except for T follicular helper (Tfh) cells. But a variety of up-regulated immune inhibitory-related molecules in bone marrow of children's B- ALL with PAX5 mutations were identified. By different approaches, we found that several immune inhibitory-related molecules of CD8+ T cells in TME of PAX5 haplodeletion clones such as TIM3, NR4A1 and BATF, were increased significantly compared with that of PAX5 wild type control. The IFN-ɤ of CD8+ T cells in TME of PAX5 haplodeletion tumors was decreased significantly compared with that of PAX5 wild type control.

CONCLUSION

Our study showed that PAX5 haploinsufficiency induced CD8+ T cells dysfunction or exhaustion by high expression of TIM3, NR4A1 and BATF in the CD8+ T cells of TME.

The role of Tim-3/Galectin-9 pathway in T-cell function and prognosis of patients with human papilloma virus-associated cervical carcinoma

The interaction between Tim-3 on T cell and its ligand, Galectin-9, negatively regulates cellular immune responses. However, the role of Tim-3/Galectin-9 pathway in the immune evasion of cervical cancer remains unknown. This study is to investigate the expression, function, and regulation of Tim-3/Galectin-9 signaling pathway in human papilloma virus (HPV) positive cervical cancer. Flow cytometry showed that Tim-3 expression on T cell and Galectin-9 expression on monocytes in HPV positive cervical cancer patients were significantly higher compared to cervical intraepithelial neoplasia and benign uterine fibroids Tim-3 + CD4+ Th1 cells and Tim-3 + CD8+ T cells in HPV positive cervical cancer patients were significantly reduced after surgery. Serum TGF-β and IL-10 levels were positively correlated with Tim-3 + Treg cells, while IFN-γ and IL-2 were negatively correlated with Tim-3 + Th1 cells. Additionally, Tim-3 + CD4+ T cells were positively correlated with Galectin-9 + monocytes. Survival curve analysis showed that Tim-3 + CD4+ T cells were negatively correlated with patient survival, and closely related to FIGO stage, degree of differentiation, and lymph node metastasis of HPV positive cervical cancer. In vitro experiments showed that by blocking the Tim-3/Galectin-9 pathway, the proliferation of T cells and their ability to express IFN-γ, IL-2, perforin, and granzyme B was significantly restored. In conclusion, high levels of Tim-3 and Galectin-9 in HPV positive cervical cancer patients play roles in the progression of disease by promoting Treg cells to inhibit the cytotoxic function of Th1 and CD8+ T cells. Tim-3/Galectin-9 may serve as a new immunotherapy target for patients with HPV positive cervical cancer.

Detection of Immune Checkpoint Receptors - A Current Challenge in Clinical Flow Cytometry

Immunological therapy principles are increasingly determining modern medicine. They are used to treat diseases of the immune system, for tumors, but also for infections, neurological diseases, and many others. Most of these therapies base on antibodies, but small molecules, soluble receptors or cells and modified cells are also used. The development of immune checkpoint inhibitors is amazingly fast. T-cell directed antibody therapies against PD-1 or CTLA-4 are already firmly established in the clinic. Further targets are constantly being added and it is becoming increasingly clear that their expression is not only relevant on T cells. Furthermore, we do not yet have any experience with the long-term systemic effects of the treatment. Flow cytometry can be used for diagnosis, monitoring, and detection of side effects. In this review, we focus on checkpoint molecules as target molecules and functional markers of cells of the innate and acquired immune system. However, for most of the interesting and potentially relevant parameters, there are still no test kits suitable for routine use. Here we give an overview of the detection of checkpoint molecules on immune cells in the peripheral blood and show examples of a possible design of antibody panels.

Development of IL-15/IL-15Rα sushi domain-IgG4 Fc complexes in Pichia pastoris with potent activities and prolonged half-lives

BACKGROUND

Interleukin-15 (IL-15) is a critical cytokine for the development, proliferation, and function of natural killer (NK) cells, NKT cells, and CD8⁺ memory T cells and has become one of the most promising protein molecules for the treatment of cancer and viral diseases. However, there are several limitations in applying IL-15 in therapy, such as its low yield in vitro, limited potency, and short half-life in vivo. To date, there are several recombinant IL-15 agonists based on configurational modifications that are being pursued in the treatment of cancer, such as ALT-803, which are mainly produced from mammalian cells.

RESULTS

In this study, we designed two different forms of the IL-15 complex, which were formed by the noncovalent assembly of IL-15 with dimeric or monomeric sushi domain of IL-15 receptor α (SuIL-15Rα)-IgG4 Fc fusion protein and designated IL-15/SuIL-15Rα-dFc and IL-15/SuIL-15Rα-mFc, respectively. The two IL-15 complexes were expressed in Pichia pastoris (P. pastoris), and their activities and half-lives were evaluated and compared. Pharmacokinetic analysis showed that IL-15/SuIL-15Rα-dFc had a half-life of 14.26 h while IL-15/SuIL-15Rα-mFc had a half-life of 9.16 h in mice, which were much longer than the 0.7-h half-life of commercial recombinant human IL-15 (rhIL-15). Treatment of mice with intravenous injection of the two IL-15 complexes resulted in significant increases in NK cells, NKT cells, and memory CD8⁺ T cells, which were not observed after rhIL-15 treatment. Treatment of human peripheral blood mononuclear cells (PBMCs) from healthy donors with the two IL-15 complexes yielded enhanced NK and CD8⁺ T cell activation and proliferation, which was comparable to the effect of rhIL-15.

CONCLUSIONS

These findings indicate that the IL-15/SuIL-15Rα-dFc and IL-15/SuIL-15Rα-mFc produced in P. pastoris exhibit potent activities and prolonged half-lives and may serve as superagonists for immunotherapy in further research and applications.

Association of soluble T cell immunoglobulin domain and mucin-3 (sTIM-3) and mac-2 binding protein glycosylation isomer (M2BPGi) in patients with autoimmune hepatitis

Background

Autoimmune hepatitis (AIH) is a disorder of unknown etiology in which immune-mediated liver injury progress to cirrhosis or hepatocellular carcinoma (HCC). The aim of the present study was to determine whether circulating soluble TIM3 (sTIM3) is elevated in patients with AIH patients and whether sTIM-3 levels are associated with clinical parameters of AIH.

Methods

We enrolled 123 Japanese patients with AIH who were identified from the National Hospital Organization–AIH-liver–network database, as well as 32 patients with chronic hepatitis C (CHC), 30 patients with primary biliary cholangitis (PBC) and healthy control subjects. Serum sTIM-3 concentrations were quantified by ELISA.

Results

Serum levels of sTIM-3 were significantly higher in AIH patients (median 4865 pg/ml; [interquartile range (IQR); 3122–7471]) compared to those in CHC (1026 pg/ml [IQR: 806–1283] p<0.001), PBC (2395 pg/ml [IQR: 2012–3422] p<0.001) or healthy controls (1285 pg/ml [IQR: 1098–1812] p<0.001). In AIH group, serum sTIM-3 were correlated with alanine aminotransferase (ALT), or total bilirubin (TB) and negatively correlated with serum levels of albumin (Alb). Serum levels of sTIM-3 were also strongly correlated with Mac-2 binding protein glycosylation isomer (M2BPGi) levels, but did not correlate with the histological grade of liver fibrosis. Steroid treatment of AIH patients significantly reduced serum sTIM-3 levels (2147±623pg/ml versus 1321±378pg/ml, p<0.001).

Conclusions

Circulating sTIM-3 levels were elevated in AIH patients and are associated with AIH disease activity and AIH-related liver damage. These findings indicate that serum sTIM-3 correlated with disease status of AIH and could be useful biomarkers to detect autoimmune-mediated liver injury. Our data suggest a possible link between the TIM-3/GAL-9 pathway and AIH severity or phenotype, and further investigations of the TIM-3 pathway and AIH pathophysiology is warranted.

New immunotherapeutic drugs in advanced non-small cell lung cancer (NSCLC): from preclinical to phase I clinical trials

INTRODUCTION

The development of immune checkpoint inhibitors (ICI) has represented a revolution in the treatment of non-small cell lung cancer (NSCLC) and has established a new standard of care for different settings. However, through adaptive changes, cancer cells can develop resistance mechanisms to these drugs, hence the necessity for novel immunotherapeutic agents.

AREAS COVERED

This paper explores the immunotherapeutics currently under investigation in phase I clinical trials for the treatment of NSCLC as monotherapies and combination therapies. It provides two comprehensive tables of phase I agents which are listed according to target, drug, drug class, mechanism of action, setting, trial identifier, and trial status. A comprehensive literature search was carried out to identify eligible studies from MEDLINE/PubMed and ClinicalTrials.gov.

EXPERT OPINION

A key hurdle to success in this field is our limited understanding of the synergic interactions of the immune targets in the context of the TME. While we can recognize the links between inhibitors and some particularly promising new targets such as TIM-3 and LAG3, we continue to develop approaches to exploit their interactions to enhance the immune response of the patient to tumor cells.

Direct-acting antiviral treatment downregulates immune checkpoint inhibitor expression in patients with chronic hepatitis C

Chronic hepatitis C (CHC) infection is associated with increased TIM-3, PD-1 immune checkpoint receptors expression that inhibits adaptive T cells and increases NK cell cytotoxicity against T helper cells, both resulting T cell exhaustion. Elimination of the virus with direct-acting antivirals (DAAs) may modify host immune response via altering these immune checkpoint receptors’ expression. We conducted a prospective study to analyze changes in TIM-3, PD-1 and their ligands galectin-9, PD-L1 expression by peripheral blood T cell subpopulations, NK cell subpopulations, and monocytes by multicolor flow cytometry in 14 CHC patients successfully treated with 12 weeks of dasabuvir, ombitasvir, and paritaprevir/ritonavir plus ribavirin. Blood samples were collected before, at the end of treatment, and 12 and 24 weeks later. Sustained virological response (SVR) was associated with increased percentage of peripheral blood CD3+ T and CD8+ cytotoxic T lymphocytes and decreased percentage of NKbright cells. After DAA treatment, decreased TIM-3 expression by CD4+ T cells, by NKbright, and by NKT cells was found. Expression of immune checkpoint molecules’ ligand PD-L1 by NK cells and by regulatory T cells and galectin-9 by NK cells and monocytes also decreased significantly at SVR. Our data suggest that DAA treatment not only inhibits viral replication but may alter host adaptive and innate immune responses. A decrease in immune checkpoint molecules and their ligands expression both on adaptive and on innate immune cells may contribute to the recovery of exhausted adaptive immune responses and to sustained virological response.

Modulation of the Immune System in Chronic Hepatitis C and During Antiviral Interferon-Free Therapy

The treatment of patients with chronic hepatitis C virus (HCV) infection has changed tremendously over the past 2 years, with an increasing variety of all-oral direct-acting antiviral (DAA) treatment regimens available for different HCV genotypes and distinct clinical settings. These treatments have significantly improved safety in patients with advanced liver disease compared with interferon (IFN)-based regimens. HCV modifies the human immune system to escape immunosurveillance via several mechanisms. One of the basic mechanisms of HCV is the ability to “switch” the immune response by reducing the activity of cells responsible for the elimination of virus-infected cells. IFN-free DAA treatment regimens provide a unique opportunity to assess the effect of HCV elimination on the immune system. Abrupt changes in the immune system can in some cases be responsible for two alarming processes: viral reactivation in patients with chronic hepatitis B and recurrence of hepatocellular carcinoma in patients with previous successful cancer treatment.

Natural killer cells in liver diseases

The liver has been characterized as a frontline lymphoid organ with complex immunological features such as liver immunity and liver tolerance. Liver tolerance plays an important role in liver diseases including acute inflammation, chronic infection, autoimmune disease, and tumors. The liver contains a large proportion of natural killer (NK) cells, which exhibit heterogeneity in phenotypic and functional characteristics. NK cell activation, well known for its role in the immune surveillance against tumor and pathogen-infected cells, depends on the balance between numerous activating and inhibitory signals. In addition to the innate direct "killer" functions, NK cell activity contributes to regulate innate and adaptive immunity (helper or regulator). Under the setting of liver diseases, NK cells are of great importance for stimulating or inhibiting immune responses, leading to either immune activation or immune tolerance. Here, we focus on the relationship between NK cell biology, such as their phenotypic features and functional diversity, and liver diseases.

Polymorphisms in TIM-3 and breast cancer susceptibility in Chinese women: A case-control study

Previous studies have found associations between polymorphisms in T cell immunoglobulin and mucin domain 3 (TIM-3) and increased risks of various cancers. However, the association between TIM-3 polymorphisms and breast cancer (BC) remains uncertain. In this study, a total of 560 BC patients and 583 age, sex, and ethnicity-matched healthy controls from Northwest China were included. The polymorphisms were genotyped using Sequenom MassARRAY. The expression level of TIM-3 protein was detected by immunohistochemistry. We observed rs10053538 had a significantly increased risk of BC, comparing with the wild-type genotype even after Bonferroni correction. In addition, the rs4704853 G>A variants were more frequent among BC patients than the controls (GA + AA vs. GG: OR = 1.32, 95% CI = 1.03-1.69, P = 0.026); However, the significance was lost after Bonferroni correction (P = 0.078). Furthermore, rs10053538 was associated with lymph node metastasis. Age stratification revealed that among patients aged <49 years, those with the rs4704853 GA/AA genotype had a higher risk of BC; But there was no difference when Bonferroni correction was conducted. Immunohistochemical analysis showed that the expression of TIM-3 protein in the breast cancer tissues was higher in patients carrying the rs10053538 GT+TT genotype than those with GG genotype (P = 0.012). However, we failed to find any difference between BC patients and controls in any rs1036199 genetic model. These findings suggested that rs10053538 in TIM-3 might increase susceptibility to BC and promote the progression of BC in Chinese women.

Higher expression of inhibitory CD158b and CD158e NK cell receptor and age predicts treatment response in children with chronic hepatitis C

Treatment with pegylated interferon-α and ribavirin (PEG-IFN/RBV) is the only choice for chronic hepatitis C (CHC) in children. Natural killer (NK) cells were described to play a vital role in CHC. The aim of this study was to analyze the expression of peripheral blood NK cell receptors in their relation to PEG-IFN/RBV treatment response. Study included 26 children with CHC-13 boys, age range 13.42 ± 3.28 years. Blood for biochemical, virological and cytometric testing was taken for evaluation prior to the antiviral treatment. NK cell receptors were detected by flow cytometry and the results were presented as proportion of cells and mean fluorescence intensity (MFI). Therapy consisted of PEG-IFNα-2b (60 μg/m² s.c 1×/week) and RBV (15 mg/kg p.o. daily). Treatment duration was response-related and varied from 12 to 72 weeks. Rapid virological response (RVR) was evaluated in the 4th week and sustained virological response (SVR) 6 months after completion of the therapy. RVR children were younger (11.67 ± 3.74 vs 15.35 ± 2.42; p = 0.001) and displayed higher CD158b (3.58 ± 0.16 vs 3.45 ± 0.13; p = 0.038) and CD158e expression (4.33 ± 0.21 vs 4.03 ± 0.16; p = 0.039). Density of CD158b (logMFI = 3.68 ± 0.22 vs 3.36 ± 0.16; p = 0.036) and CD158e expression was significantly higher (4.37 ± 0.14 vs 4.12 ± 0.21; p = 0.046) and NKG2D expression significantly lower (97.50 ± 3.46 vs 94.92 ± 5.93; p = 0.049) in SVR children. SVR children were also significantly younger (12.40 ± 3.66 vs 15.13 ± 2.83; p = 0.003). Significance of the age of patients, and expression of CD158b and CD158e were confirmed in univariate and multivariate analysis. Age of patients is negatively related to RVR and SVR. NK cell phenotype with higher expression density of CD158b and CD158e receptor was a positive predictor of SVR.

Tim-3在肝脏疾病中的调节作用

T淋巴细胞免疫球蛋白黏蛋白分子(T-cell immunoglobulin domain and mucin domain-containing molecule, Tim)-3是Tim家族中的一员, 为近年来新发现的一种在辅助Ⅰ型T淋巴细胞(Help T cell 1, Th1)上特异性表达的Ⅰ型细胞表面分子. Tim-3作为负性调节因子通过与其配体Galectin-9结合引起细胞死亡, 进而调控Th1型细胞功能. Tim-3还表达于其他类型细胞表面, 如自然杀伤细胞、树突状细胞和单核细胞, 对自身免疫性疾病和其他免疫介导的疾病进行免疫调控. 对Tim-3在不同细胞不同免疫条件下的功能以及如何调节进行研究, 将有利于研发Tim-3的潜在治疗作用. 近年来大量研究显示Tim-3通道与肝脏疾病发生发展有着密切关系, 本文就其在肝脏疾病中的调节作用做一总结.

Interaction between Galectin-9/TIM-3 pathway and follicular helper CD4+ T cells contributes to viral persistence in chronic hepatitis C

Both Galectin 9 (Gal-9)/T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) pathway and follicular helper CD4⁺ T (Tfh) cells play important roles in persistent hepatitis C virus (HCV) infection. Thus, we aimed to investigate the regulatory role of interaction between Gal-9/TIM-3 pathway and Tfh cells in chronic hepatitis C. A total of 44 chronic hepatitis C patients and 19 normal controls (NCs) were enrolled in this study. Purified CD4⁺ T cells were cultured by TIM-3 Fc protein, recombinant Gal-9, or IL-21 for 48h. TIM-3 expression, Tfh proportion, and IL-21 production was measured, respectively. The immunomodulatory role of Gal-9/TIM-3 and IL-21 was also investigated in HCV cell culture system in vitro. We found that the percentage corresponding to both TIM-3-positive and CXCR5⁺ICOS⁺ Tfh cells within CD4⁺ T cells, which correlated with HCV RNA replication, was significantly elevated in patients with chronic hepatitis C in comparison with those in NCs. Moreover, blockade of Gal-9/TIM-3 pathway by TIM-3 Fc protein increased Tfh cells proportion, IL-21 mRNA and protein expression within purified CD4⁺ T cells, while activation of Gal-9/TIM-3 signaling by Gal-9 stimulation decreased IL-21 production in both patients with chronic HCV infection and healthy individuals. Meanwhile, high concentrations (100 and 200ng/mL) of IL-21 stimulation also elevated TIM-3 expression on CD4⁺ T cells in chronic hepatitis C. Furthermore, TIM-3 blockage and IL-21 stimulation suppressed mRNA expressions of HCV-induced antiviral proteins (myxovirus resistance A and oligoadenylate synthetase) in Huh7.5 cells without affecting viral replication in HCV cell culture system. The interaction between Gal-9/TIM-3 pathway and Tfh cells contributed to viral persistent in chronic HCV infection, which might be pivotal for development of new therapeutic approaches for chronic hepatitis C.

Programmed Cell Death 1 (PD-1) and Cytotoxic T Lymphocyte-Associated Antigen 4 (CTLA-4) in Viral Hepatitis

Virus-specific cluster of differentiation 8 (CD8+) cytotoxic T cells (CTL) recognize viral antigens presented on major histocompatibility complex (MHC) class I chains on infected hepatocytes, with help from CD4+ T cells. However, this CTL response is frequently weak or undetectable in patients with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. Programmed cell death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) are receptors in the CD28 family of costimulatory molecules, providing inhibitory signals to T cells. The overexpressions of PD-1 and CTLA-4 in patients with viral infection have been shown to associate with functional impairment of virus-specific T cells. In acute viral hepatitis, PD-1 and CTLA-4 are up-regulated during the symptomatic phase, and then down-regulated after recovery. These findings suggest that PD-1 and CTLA-4 have protective effects as inhibitory molecules to suppress cytotoxic T cells which induce harmful destruction of viral infected hepatocytes in self-limited viral hepatitis. In chronic viral hepatitis, the extended upregulations of PD-1 and CTLA-4 are associated with T cell exhaustion and persistent viral infection, suggesting positive correlations between expression of immune inhibitory factors and the chronicity of viral disease. In this review, we summarize recent literature relating to PD-1, CTLA-4, and other inhibitory receptors in antigen-specific T cell exhaustion in viral hepatitis, including hepatitis A, B, C, and others.

Preoperative Tim‑3 expression on peripheral NK cells is correlated with pathologic TNM staging in colorectal cancer

Previous research has indicated that T cell immunoglobulin and mucin domain 3 (Tim-3) serves an important regulatory role in lymphocytes and in several cancers. However, the association between Tim‑3 expression on various lymphocyte subsets and human colorectal cancer (CRC) has not been elucidated. The present study aimed to characterize Tim‑3 expression on peripheral lymphocytes, including cluster of differentiation CD3+CD56‑ T cells, CD3‑CD56+ natural killer (NK) cells and CD3+CD56+ natural killer T (NKT) cells, in patients with CRC. The frequency of T cells, NK cells and NKT cells expressing Tim‑3 was assessed by multicolor flow cytometry of peripheral blood collected from 36 preoperative CRC patients and 38 healthy donors. The expression of Tim‑3 on lymphocyte subsets from 53 postoperative blood samples of CRC patients was also analyzed. There were fewer circulating NK cells in patients with CRC compared with healthy controls (P=0.0027); NK cell expression of Tim‑3 was also significantly decreased (P=0.0239). The frequency of circulating NK cells and Tim‑3+ NK cells was negatively correlated with clinical cancer stage, compared with healthy controls, but not with other clinicopathological parameters or serum concentrations of CRC biomarkers. Furthermore, the expression of Tim‑3 in NK cells was higher in CRC patients without metastasis. Notably, NK cell Tim‑3 expression in CRC patients was significantly restored following surgical resection of the primary tumor. In conclusion, the present study indicates the presence of an altered frequency and expression of Tim‑3 in peripheral NK cells in CRC patients. Preoperative Tim‑3 expression on peripheral NK cells is correlated with differential staging in colorectal cancer, and may be useful as a serum biomarker.

Natural killer cells in inflammatory heart disease

Despite of a multitude of excellent studies, the regulatory role of natural killer (NK) cells in the pathogenesis of inflammatory cardiac disease is greatly underappreciated. Clinical abnormalities in the numbers and functions of NK cells are observed in myocarditis and inflammatory dilated cardiomyopathy (DCMi) as well as in cardiac transplant rejection [1-6]. Because treatment of these disorders remains largely symptomatic in nature, patients have little options for targeted therapies [7,8]. However, blockade of NK cells and their receptors can protect against inflammation and damage in animal models of cardiac injury and inflammation. In these models, NK cells suppress the maturation and trafficking of inflammatory cells, alter the local cytokine and chemokine environments, and induce apoptosis in nearby resident and hematopoietic cells [1,9,10]. This review will dissect each protective mechanism employed by NK cells and explore how their properties might be exploited for their therapeutic potential.

Immune regulation in chronic hepatitis C virus infection

The immunological result of infection with Hepatitis C virus (HCV) depends on the delicate balance between a vigorous immune response that may clear the infection, but with a risk of unspecific inflammation and, or a less inflammatory response that leads to chronic infection. In general, exhaustion and impairment of cytotoxic function of HCV-specific T cells and NK cells are found in patients with chronic HCV infection. In contrast, an increase in immune regulatory functions is found primarily in form of increased IL-10 production possibly due to increased level and function of anti-inflammatory Tregs. Thus, the major immune players during chronic HCV infection are characterized by a decrease of cytotoxic function and increase of inhibitory functions. This may be an approach to diminish intrahepatic and systemic inflammation. Finally, there has been increasing awareness of regulatory functions of epigenetic changes in chronic HCV infection. A vast amount of studies have revealed the complexity of immune regulation in chronic HCV infection, but the interplay between immune regulation in virus and host remains incompletely understood. This review provides an overview of regulatory functions of HCV-specific T cells, NK cells, Tregs, IL-10, and TGF-β, as well as epigenetic changes in the setting of chronic HCV infection.

Direct-Acting Antiviral-Induced Hepatitis C Virus Clearance Does Not Completely Restore the Altered Cytokine and Chemokine Milieu in Patients With Chronic Hepatitis C

BACKGROUND

 Persistent infection with hepatitis C virus (HCV) causes profound alterations of the cytokine and chemokine milieu in peripheral blood. However, it is unknown to what extend these alterations affect the progression of liver disease and whether HCV clearance normalizes soluble inflammatory mediators.

METHODS

 We performed multianalyte profiling of 50 plasma proteins in 28 patients with persistent HCV infection and advanced stages of liver fibrosis or cirrhosis and 20 controls with fatty liver disease. The patients were treated for 24 weeks with sofosbuvir and ribavirin and underwent sampling longitudinally. Ten patients experienced viral relapse after treatment cessation.

RESULTS

 The cytokine and chemokine expression pattern was markedly altered in patients with chronic HCV infection as compared to healthy controls and patients with nonalcoholic steatohepatitis. Distinct soluble factors were associated with the level of fibrosis/cirrhosis, viral replication, or treatment outcome. The baseline expression level of 10 cytokines distinguished patients with a sustained viral response from those who experienced viral relapse. While the majority of upregulated analytes declined during and after successful therapy, HCV clearance did not lead to a restoration of parameters that were suppressed.

CONCLUSIONS

 Chronic HCV infection appears to disrupt the milieu of soluble inflammatory mediators even after viral clearance. Thus, HCV cure does not lead to complete immunological restitution.

The relevance of Tim-3 polymorphisms and F protein to the outcomes of HCV infection

Hepatitis C virus (HCV) is one of the major causes of liver inflammation. The aim of this study was to investigate the associations of T-cell immunoglobulin and mucin domain-3 (Tim-3) polymorphisms and the alternate reading frame protein (F protein) with the outcomes of HCV infection. Three single-nucleotide polymorphisms (SNPs; rs10053538, rs12186731, and rs13170556) of Tim-3 were genotyped in this study, which included 203 healthy controls, 558 hepatitis C anti-F-positive patients, and 163 hepatitis C anti-F-negative patients. The results revealed that the rs12186731 CT and rs13170556 TC and CC genotypes were significantly less frequent in the anti-F-positive patients [odds ratio (OR) = 0.54, 95 % confidence interval (CI) = 0.35-0.83, p = 0.005; OR = 0.26, 95 % CI = 0.18-0.39, p < 0.001; and OR = 0.19, 95 % CI = 0.10-0.35, p < 0.001, respectively), and the rs13170556 TC genotype was more frequent in the chronic HCV (CHC) patients (OR = 1.70, 95 % CI = 1.20-2.40, p = 0.002). The combined analysis of the rs12186731 CT and rs13170556 TC/CC genotypes revealed a locus-dosage protective effect in the anti-F-positive patients (OR = 0.22, 95 % CI = 0.14-0.33, p trend < 0.001). Stratified analyses revealed that the frequencies of the rs12186731 (CT + TT) genotypes were significantly lower in the older (OR = 0.31, 95 % CI = 0.15-0.65, p = 0.002) and female (OR = 0.30, 95 % CI = 0.17-0.52, p < 0.001) subgroups, and rs13170556 (TC + CC) genotypes exhibited the same effect in all subgroups (all p < 0.001) in the anti-F antibody generations. Moreover, the rs13170556 (TC + CC) genotypes were significantly more frequent in the younger (OR = 1.86, 95 % CI = 1.18-2.94, p = 0.007) and female (OR = 2.38, 95 % CI = 1.48-3.83, p < 0.001) subgroups of CHC patients. These findings suggest that the rs12186731 CT and rs13170556 TC/CC genotypes of Tim-3 provide potential protective effects with the F protein in the outcomes of HCV infection and that these effects are related to sex and age.

Tim-3 expression represents dysfunctional tumor infiltrating T cells in renal cell carcinoma

PURPOSE

Renal cell carcinoma (RCC) is the most common cancer of kidney. Evidences have shown that RCC is sensitive to various immunotherapies. Tim-3 plays a role in suppressing Th1-mediated immune responses. However, no study has yet examined the effect of Tim-3 on tumor infiltrating lymphocytes (TILs) in RCC.

METHODS

We investigated the expression and function of Tim-3 on TIL CD4+ T cells and TIL CD8+ T cells from 30 RCC patients.

RESULTS

Levels of Tim-3 were significantly increased on both TIL CD4+ T cells and TIL CD8+ T cells and were associated with higher stages of the cancer. Also, GATA-3 and interferon gamma (IFN-γ) were down-regulated, whereas T-bet was up-regulated in TIL Tim-3+ T cells, indicating that Tim-3 expression defined a population of dysfunctional TIL Th1/Tc1 cells. Mechanism analyses showed that TIL Tim-3-expressing CD8+ T cells exhibited impaired Stat5 and p38 signaling pathway. Blocking the Tim-3 pathway restored cell proliferation and increased IFN-γ production in TIL CD4+ and CD8+ T cells of RCC.

CONCLUSIONS

These results suggest that Tim-3 may be used as a novel target for increasing immune responses in RCC tumor microenvironment.

Role of Tim-3 in hepatitis B virus infection: An overview

Hepatitis B virus (HBV) infection has received increasing public attention. HBV is the prototypical member of hepadnaviruses, which naturally infect only humans and great apes and induce the acute and persistent chronic infection of hepatocytes. A large body of evidence has demonstrated that dysfunction of the host anti-viral immune response is responsible for persistent HBV replication, unresolved inflammation and disease progression. Many regulatory factors are involved in immune dysfunction. Among these, T cell immunoglobulin domain and mucin domain-3 (Tim-3), one of the immune checkpoint proteins, has attracted increasing attention due to its critical role in regulating both adaptive and innate immune cells. In chronic HBV infection, Tim-3 expression is elevated in many types of immune cells, such as T helper cells, cytotoxic T lymphocytes, dendritic cells, macrophages and natural killer cells. Tim-3 over-expression is often accompanied by impaired function of the above-mentioned immunocytes, and Tim-3 inhibition can at least partially rescue impaired immune function and thus promote viral clearance. A better understanding of the regulatory role of Tim-3 in host immunity during HBV infection will shed new light on the mechanisms of HBV-related liver disease and suggest new therapeutic methods for intervention.

Memory re-differentiation and reduced lymphocyte activation in chronic HCV-infected patients receiving direct-acting antivirals

Recently, the treatment of HCV has advanced significantly due to the introduction of direct-acting antivirals (DAAs). Studies using interferon (IFN)-containing regimens failed to consistently show restoration of immunologic responses. Therefore, IFN-free DAA formulations provide a unique opportunity to dissect the immunologic effect of HCV cure. This study investigates the restoration of the immune compartment as a consequence of rapid viral clearance in patients successfully treated with DAAs and in the absence of IFN and ribavirin. Here, we evaluate the immunologic changes that occurred following DAA-mediated HCV cure. Peripheral blood from nineteen previously treatment-naïve patients with chronic HCV genotype 1a/1b who received an IFN and ribavirin-free regimen of daclatasvir, asunaprevir and BMS-791325 was evaluated. Immune reconstitution occurs in patients in whom HCV was successfully eradicated via DAA therapy. Restoration of the CD4(+) T-cell compartment in the peripheral blood and a re-differentiation of the T lymphocyte memory compartment resulted in a more effector memory cell population and a reduction in expression in the co-inhibitory molecule TIGIT in bulk T lymphocytes. Furthermore, we observed a partial reversal of the exhausted phenotype in HCV-specific CD8(+) T cells and a dampening of the activation state in peripheral NK cells. Collectively, our data provide the groundwork for dissecting the effect of DAA therapy on the immune system and identifying novel mechanisms by which chronic HCV infection exerts immunosuppressive effects on T cells through the recently described co-inhibitory molecule TIGIT.