TIM-3 and its regulatory role in immune responses

The Role of Astrocytes in Multiple Sclerosis Progression

Multiple sclerosis (MS) is an inflammatory disorder causing central nervous system (CNS) demyelination and axonal injury. Although its etiology remains elusive, several lines of evidence support the concept that autoimmunity plays a major role in disease pathogenesis. The course of MS is highly variable; nevertheless, the majority of patients initially present a relapsing–remitting clinical course. After 10–15 years of disease, this pattern becomes progressive in up to 50% of untreated patients, during which time clinical symptoms slowly cause constant deterioration over a period of many years. In about 15% of MS patients, however, disease progression is relentless from disease onset. Published evidence supports the concept that progressive MS reflects a poorly understood mechanism of insidious axonal degeneration and neuronal loss. Recently, the type of microglial cell and of astrocyte activation and proliferation observed has suggested contribution of resident CNS cells may play a critical role in disease progression. Astrocytes could contribute to this process through several mechanisms: (a) as part of the innate immune system, (b) as a source of cytotoxic factors, (c) inhibiting remyelination and axonal regeneration by forming a glial scar, and (d) contributing to axonal mitochondrial dysfunction. Furthermore, regulatory mechanisms mediated by astrocytes can be affected by aging. Notably, astrocytes might also limit the detrimental effects of pro-inflammatory factors, while providing support and protection for oligodendrocytes and neurons. Because of the dichotomy observed in astrocytic effects, the design of therapeutic strategies targeting astrocytes becomes a challenging endeavor. Better knowledge of molecular and functional properties of astrocytes, therefore, should promote understanding of their specific role in MS pathophysiology, and consequently lead to development of novel and more successful therapeutic approaches.

Regulation of T cell responses by the receptor molecule Tim-3

Tim-3 is a member of the T cell immunoglobulin and mucin domain (Tim) family of proteins, which are expressed by several cell types in the immune system, including CD4 and CD8 T cells activated under certain conditions. These molecules are generally thought to act as receptors for multiple ligands and thus to function by engaging intracellular signaling pathways in a ligand-dependent manner. In recent years, the function of the Tim-3 protein has been studied in some detail, particularly with respect to its role in the regulation of CD4 and CD8 T cell responses. Here, we review the structural features of Tim-3, known ligands for this molecule and the links established between Tim-3 and signal transduction pathways. In addition, we review the current literature regarding the role of Tim-3 in the regulation of effector responses by CD4 and CD8 T cells. Overall, findings published thus far strongly support the conclusion that Tim-3 functions to inhibit T cell responses, particularly under conditions involving chronic stimulation. Conversely, some reports have provided evidence that Tim-3 can stimulate T cells under conditions involving acute stimulation, suggesting that the role of Tim-3 may vary depending on context. Further study of Tim-3 is likely to advance our understanding of how CD4 and CD8 T cell responses are regulated and could uncover novel approaches for manipulating T cell function for therapeutic benefit.

The HIF-1/glial TIM-3 axis controls inflammation-associated brain damage under hypoxia

Inflammation is closely related to the extent of damage following cerebral ischaemia, and the targeting of this inflammation has emerged as a promising therapeutic strategy. Here, we present that hypoxia-induced glial T-cell immunoglobulin and mucin domain protein (TIM)-3 can function as a modulator that links inflammation and subsequent brain damage after ischaemia. We find that TIM-3 is highly expressed in hypoxic brain regions of a mouse cerebral hypoxia-ischaemia (H/I) model. TIM-3 is distinctively upregulated in activated microglia and astrocytes, brain resident immune cells, in a hypoxia-inducible factor (HIF)-1-dependent manner. Notably, blockade of TIM-3 markedly reduces infarct size, neuronal cell death, oedema formation and neutrophil infiltration in H/I mice. Hypoxia-triggered neutrophil migration and infarction are also decreased in HIF-1α-deficient mice. Moreover, functional neurological deficits after H/I are significantly improved in both anti-TIM-3-treated mice and myeloid-specific HIF-1α-deficient mice. Further understanding of these insights could serve as the basis for broadening the therapeutic scope against hypoxia-associated brain diseases.

Galectin-9 predicts postoperative recurrence and survival of patients with clear-cell renal cell carcinoma

Galectin-9 (Gal-9), a member of animal lectin family with evolutionary conserved carbohydrate recognition domains, has been reported to exert a large variety of functional roles in tumorigenesis due to its β-galactoside-binding affinity. The aim of this study is to evaluate the expression and prognostic significance of Gal-9 in patients with clear-cell renal cell carcinoma (ccRCC). The expression of Gal-9 was assessed by immunohistochemistry in 196 patients with ccRCC who underwent nephrectomy. In the cohort, 48 patients died and 61 patients suffered recurrence. Kaplan-Meier method with log-rank test was applied to compare survival curves. The authors employed univariate and multivariate Cox regression models to evaluate the prognostic value of Gal-9 expression in overall survival (OS) and recurrence-free survival (RFS). In patients with ccRCC, Gal-9 expression, which was positively associated with tumor size (P = 0.014), Fuhrman grade (P = 0.010), and necrosis (P = 0.025), was determined to be an independent prognostic indicator for OS (hazard ratio [HR] 2.394; P = 0.005) and RFS (HR 2.096; P = 0.006). High expression of Gal-9 was associated with poor survival (P = 0.001) and early recurrence (P = 0.006). Furthermore, Gal-9 expression could significantly stratify the patients in early (grades I + II) tumor, node, and metastasis (TNM) stage (OS: P = 0.005; RFS: P = 0.041) and low (grades 1 + 2) Fuhrman grade (OS: P = 0.004; RFS: P = 0.006). The prognostic accuracy of TNM, SSIGN, and UISS prognostic models was improved when Gal-9 expression was added. Gal-9 expression is a potential independent prognostic factor for OS and RFS in patients with ccRCC.

An IL-27/NFIL3 signalling axis drives Tim-3 and IL-10 expression and T-cell dysfunction

The inhibitory receptor T-cell immunoglobulin and mucin domain-3 (Tim-3) has emerged as a critical regulator of the T-cell dysfunction that develops in chronic viral infections and cancers. However, little is known regarding the signalling pathways that drive Tim-3 expression. Here, we demonstrate that interleukin (IL)-27 induces nuclear factor, interleukin 3 regulated (NFIL3), which promotes permissive chromatin remodelling of the Tim-3 locus and induces Tim-3 expression together with the immunosuppressive cytokine IL-10. We further show that the IL-27/NFIL3 signalling axis is crucial for the induction of Tim-3 in vivo. IL-27-conditioned T helper 1 cells exhibit reduced effector function and are poor mediators of intestinal inflammation. This inhibitory effect is NFIL3 dependent. In contrast, tumour-infiltrating lymphocytes from IL-27R(-/-) mice exhibit reduced NFIL3, less Tim-3 expression and failure to develop dysfunctional phenotype, resulting in better tumour growth control. Thus, our data identify an IL-27/NFIL3 signalling axis as a key regulator of effector T-cell responses via induction of Tim-3, IL-10 and T-cell dysfunction.

Identification and targeting leukemia stem cells: The path to the cure for acute myeloid leukemia

Accumulating evidence support the notion that acute myeloid leukemia (AML) is organized in a hierarchical system, originating from a special proportion of leukemia stem cells (LSC). Similar to their normal counterpart, hematopoietic stem cells (HSC), LSC possess self-renewal capacity and are responsible for the continued growth and proliferation of the bulk of leukemia cells in the blood and bone marrow. It is believed that LSC are also the root cause for the treatment failure and relapse of AML because LSC are often resistant to chemotherapy. In the past decade, we have made significant advancement in identification and understanding the molecular biology of LSC, but it remains a daunting task to specifically targeting LSC, while sparing normal HSC. In this review, we will first provide a historical overview of the discovery of LSC, followed by a summary of identification and separation of LSC by either cell surface markers or functional assays. Next, the review will focus on the current, various strategies for eradicating LSC. Finally, we will highlight future directions and challenges ahead of our ultimate goal for the cure of AML by targeting LSC.

Enhanced suppressor function of TIM-3+ FoxP3+ regulatory T cells

T-cell immunoglobulin and mucin domain 3 (TIM-3) is an Ig-superfamily member expressed on IFN-γ-secreting Th1 and Tc1 cells and was identified as a negative regulator of immune tolerance. TIM-3 is expressed by a subset of activated CD4(+) T cells, and anti-CD3/anti-CD28 stimulation increases both the level of expression and the number of TIM-3(+) T cells. In mice, TIM-3 is constitutively expressed on natural regulatory T (Treg) cells and has been identified as a regulatory molecule of alloimmunity through its ability to modulate CD4(+) T-cell differentiation. Here, we examined TIM-3 expression on human Treg cells to determine its role in T-cell suppression. In contrast to mice, TIM-3 is not expressed on Treg cells ex vivo but is upregulated after activation. While TIM-3(+) Treg cells with increased gene expression of LAG3, CTLA4, and FOXP3 are highly efficient suppressors of effector T (Teff) cells, TIM-3(-) Treg cells poorly suppressed Th17 cells as compared with their suppression of Th1 cells; this decreased suppression ability was associated with decreased STAT-3 expression and phosphorylation and reduced gene expression of IL10, EBI3, GZMB, PRF1, IL1Rα, and CCR6. Thus, our results suggest that TIM-3 expression on Treg cells identifies a population highly effective in inhibiting pathogenic Th1- and Th17-cell responses.

Tim-3 directly enhances CD8 T cell responses to acute Listeria monocytogenes infection

T cell Ig and mucin domain (Tim) 3 is a surface molecule expressed throughout the immune system that can mediate both stimulatory and inhibitory effects. Previous studies have provided evidence that Tim-3 functions to enforce CD8 T cell exhaustion, a dysfunctional state associated with chronic stimulation. In contrast, the role of Tim-3 in the regulation of CD8 T cell responses to acute and transient stimulation remains undefined. To address this knowledge gap, we examined how Tim-3 affects CD8 T cell responses to acute Listeria monocytogenes infection. Analysis of wild-type (WT) mice infected with L. monocytogenes revealed that Tim-3 was transiently expressed by activated CD8 T cells and was associated primarily with acquisition of an effector phenotype. Comparison of responses to L. monocytogenes by WT and Tim-3 knockout (KO) mice showed that the absence of Tim-3 significantly reduced the magnitudes of both primary and secondary CD8 T cell responses, which correlated with decreased IFN-γ production and degranulation by Tim-3 KO cells stimulated with peptide Ag ex vivo. To address the T cell-intrinsic role of Tim-3, we analyzed responses to L. monocytogenes infection by WT and Tim-3 KO TCR-transgenic CD8 T cells following adoptive transfer into a shared WT host. In this setting, the accumulation of CD8 T cells and the generation of cytokine-producing cells were significantly reduced by the lack of Tim-3, demonstrating that this molecule has a direct effect on CD8 T cell function. Combined, our results suggest that Tim-3 can mediate a stimulatory effect on CD8 T cell responses to an acute infection.

Hierarchical and selective roles of galectins in hepatocarcinogenesis, liver fibrosis and inflammation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents a global health problem. Infections with hepatitis B or C virus, non-alcoholic steatohepatitis disease, alcohol abuse, or dietary exposure to aflatoxin are the major risk factors to the development of this tumor. Regardless of the carcinogenic insult, HCC usually develops in a context of cirrhosis due to chronic inflammation and advanced fibrosis. Galectins are a family of evolutionarily-conserved proteins defined by at least one carbohydrate recognition domain with affinity for β-galactosides and conserved sequence motifs. Here, we summarize the current literature implicating galectins in the pathogenesis of HCC. Expression of "proto-type" galectin-1, "chimera-type" galectin-3 and "tandem repeat-type" galectin-4 is up-regulated in HCC cells compared to their normal counterparts. On the other hand, the "tandem-repeat-type" lectins galectin-8 and galectin-9 are down-regulated in tumor hepatocytes. The abnormal expression of these galectins correlates with tumor growth, HCC cell migration and invasion, tumor aggressiveness, metastasis, postoperative recurrence and poor prognosis. Moreover, these galectins have important roles in other pathological conditions of the liver, where chronic inflammation and/or fibrosis take place. Galectin-based therapies have been proposed to attenuate liver pathologies. Further functional studies are required to delineate the precise molecular mechanisms through which galectins contribute to HCC.

Immunomodulatory therapy for melanoma: ipilimumab and beyond

In 2011, the U.S. Food and Drug Administration approved the first new therapy for melanoma in more than a decade, ipilimumab (Yervoy). Ipilimumab is a novel antibody that blocks cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), a regulatory molecule expressed on activated T cells. Blockade of this important immune checkpoint can lead to durable tumor regression, and phase III studies show an overall survival benefit for patients with advanced melanoma. During the clinical development of ipilimumab, several unique features of this immunotherapy were identified, including the remarkable durability of responses and a distinct side-effects profile. We review the preclinical and clinical development of CTLA-4-blocking antibodies and describe current practices using ipilimumab for the treatment of advanced melanoma. Unique clinical issues related to ipilimumab will be summarized. Lastly, we will briefly preview combination therapies that incorporate ipilimumab and new checkpoint-targeting antibodies currently in clinical development.

Immunomodulatory therapy for melanoma: ipilimumab and beyond

In 2011, the U.S. Food and Drug Administration approved the first new therapy for melanoma in more than a decade, ipilimumab (Yervoy). Ipilimumab is a novel antibody that blocks cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), a regulatory molecule expressed on activated T cells. Blockade of this important immune checkpoint can lead to durable tumor regression, and phase III studies show an overall survival benefit for patients with advanced melanoma. During the clinical development of ipilimumab, several unique features of this immunotherapy were identified, including the remarkable durability of responses and a distinct side-effects profile. We review the preclinical and clinical development of CTLA-4-blocking antibodies and describe current practices using ipilimumab for the treatment of advanced melanoma. Unique clinical issues related to ipilimumab will be summarized. Lastly, we will briefly preview combination therapies that incorporate ipilimumab and new checkpoint-targeting antibodies currently in clinical development.

Dysregulated Tim-3 expression on natural killer cells is associated with increased Galectin-9 levels in HIV-1 infection

Background

Natural killer (NK) cells constitutively express high levels of Tim-3, an immunoregulatory molecule recently proposed to be a marker for mature and functional NK cells. Whether HIV-1 infection modulates the expression of Tim-3 on NK cells, or the levels of its ligand Galectin-9 (Gal-9), and how signaling through these molecules affects the NK cell response to HIV-1 remains inadequately understood.

Results

We analyzed Tim-3 and Gal-9 expression in a cohort of 85 individuals with early and chronic HIV-1 infection, and in 13 HIV-1 seronegative control subjects. HIV-1 infection was associated with reduced expression of Tim-3 on NK cells, which was normalized by HAART. Plasma concentrations of Gal-9 were higher in HIV-1-infected individuals than in healthy individuals. Interestingly, Gal-9 expression in immune cells was significantly elevated in early infection, with monocytes and dendritic cells displaying the highest expression levels, which correlated with HIV-1 viral loads. In vitro, Gal-9 triggered Tim-3 downregulation on NK cells as well as NK cell activation.

Conclusions

Our data suggest that high expression levels of Gal-9 during early HIV-1 infection can lead to enhanced NK cell activity, possibly allowing for improved early control of HIV-1. In contrast, persistent Gal-9 production might impair Tim-3 activity and contribute to NK cell dysfunction in chronic HIV-1 infection.

Dysregulated expression of T cell immunoglobulin and mucin domain 3 is associated with the disease severity and the outcome of patients with spontaneous intracerebral hemorrhage

OBJECTIVES

We aimed to investigate the expression of T cell immunoglobulin and mucin domain 3 (Tim-3) on peripheral blood cells in spontaneous intracerebral hemorrhage (ICH) patients and to analyze its clinical significance.

DESIGN AND METHODS

Tim-3 expression on peripheral immunocytes from ICH patients and healthy volunteers was measured by flow cytometry. The correlation between Tim-3 expression and the clinical indices was estimated using linear regression.

RESULTS

Tim-3 expressions on peripheral CD3⁺ T cells and CD8⁺ T cells in ICH patients are significantly downregulated, while Tim-3 expressions on CD14⁺ monocytes and CD16⁺CD56⁺ NK cells are increased. Furthermore, Tim-3 expression on peripheral CD8⁺ cells was negatively correlated with the inflammatory response, the disease severity and the outcome of ICH patients. However, there was no relationship between Tim-3 expression and blood glucose concentration.

CONCLUSIONS

Altered expression of Tim-3 might play an important role in the pathogenesis of ICH, demonstrating that Tim-3 might be a novel candidate molecule for prognosis evaluation of ICH patients.

Expression of Tim-1 and Tim-3 in Plasmodium berghei ANKA infection

Cerebral malaria (CM) is a serious and often fatal complication of Plasmodium falciparum infections; however, the precise mechanisms leading to CM is poorly understood. Mouse malaria models have provided insight into the key events in pathogenesis of CM. T-cell immune response is known to play an important role in malaria infection, and members of the T-cell immunoglobulin- and mucin-domain-containing molecule (Tim) family have roles in T-cell-mediated immune responses. Tim-1 and Tim-3 are expressed on terminally differentiated Th2 and Th1 cells, respectively, and participate in the regulation of Th immune response. Until now, the role of Tim family proteins in Plasmodium infection remains unclear. In the present study, the mRNA levels of Tim-1, Tim-3, and some key Th1 and Th2 cytokines in the spleen of Kunming outbred mice infected with Plasmodium berghei ANKA (PbANKA) were determined using real-time polymerase chain reaction (qRT-PCR). Compared with uninfected controls, Tim-1 expression was significantly decreased in infected mice with CM at day 10 postinfection (p.i.) but significantly increased in infected mice with non-CM at day 22 p.i.; in contrast, Tim-3 expression was significantly increased in infected mice both with CM at day 10 p.i. and with non-CM at day 22 p.i. The expressions of IFN-γ, TNF-α, IL-10, and IL-12 were significantly increased but IL-4 was significantly decreased in infected mice with CM at days 10 p.i., whereas the expressions of IFN-γ, TNF-α, IL-4, IL-10, and TGF-β were significantly increased but IL-12 was significantly decreased in infected mice with non-CM at days 22 p.i. Furthermore, the expression of Tim-1 and Tim-3 could reflect Th2 and Th1 immune response in the spleen of PbANKA-infected mice, respectively. Our data suggest that PbANKA infection could inhibit the differentiation of T lymphocytes toward Th2 cells, promote the Th1 cell differentiation, and induce Th1-biased immune response in the early infective stage, whereas the infection could promote Th2 cell differentiation and induce Th2-biased immune response in the late infective stage. Our data indicate that both Tim-1 and Tim-3 may play a role in the process of PbANKA infection, which may represent a potential therapeutic target.

Upregulated expression of Tim-3 involved in the process of toxoplasmic encephalitis in mouse model

Toxoplasma gondii can establish chronic infection and is characterized by the formation of tissue cysts in the brain. The cysts may remain throughout the life of the host but can reactivate and cause life-threatening toxoplasmic encephalitis (TE) in immunocompromised patients. T cell-mediated immune responses are essential for preventing the reactivation of chronic infection of T. gondii in the brain. The immunoinhibitory receptor T cell immunoglobulin and mucin domain (Tim)-1 and Tim-3 are expressed on terminally differentiated T helper (Th) 2 and Th1 cells, respectively, participating in the regulation of Th immune response. However, there is no report concerning the role of Tim genes in TE. In this study, Kunming outbred mice were infected with Prugniaud (Pru), a type II strain of T. gondii by oral gavage. Compared with the uninfected controls, there were mild brain inflammations at 3 weeks postinfection (p.i.), moderate brain inflammations at 5 weeks p.i., and aggravated brain inflammations and necrosis at 7 and 9 weeks p.i. The expressions of tachyzoite stage-specific genes in brains were consistent with the severity of brain histopathology of TE at 5 and 7 weeks p.i., while the expressions of bradyzoite stage-specific genes in brains were significantly increased at 7 and 9 weeks p.i. Using quantitative real-time PCR detection and immunohistochemistry staining, our results showed that the expressions of Tim-3 were significantly upregulated in both brains and spleens at 5 weeks p.i. and in spleens at 9 weeks p.i., which showed the similar dynamic tendency as that of interferon-γ expressions in both brains and spleens at the same times. In contrast, the Th2-specific marker Tim-1 expressions were significantly downregulated in both brains and spleens at 3 weeks p.i. and upregulated in both brains and spleens at 7 and 9 weeks p.i., which showed the similar dynamic tendency as that of interleukin-4 expressions in both brains and spleens at the same time. Our data indicate that Tim-3 may involve in the process of TE in mice infected with T. gondii Pru strain.

Coinhibitory molecules in cancer biology and therapy

The adaptive immune response is controlled by checkpoints represented by coinhibitory molecules, which are crucial for maintaining self-tolerance and minimizing collateral tissue damage under physiological conditions. A growing body of preclinical evidence supports the hypothesis that unleashing this immunological break might be therapeutically beneficial in the fight against cancer, as it would elicit an effective antitumor immune response. Remarkably, recent clinical trials have demonstrated that this novel strategy can be highly effective in the treatment of patients with cancer, as shown by the paradigmatic case of ipilimumab (a monoclonal antibody blocking the coinhibitory molecule cytotoxic T lymphocyte associated antigen-4 [CTLA4]) that is opening a new era in the therapeutic approach to a chemoresistant tumor such as cutaneous melanoma. In this review we summarize the biology of coinhibitory molecules, overview the experimental and clinical attempts to interfere with these immune checkpoints to treat cancer and critically discuss the challenges posed by such a promising antitumor modality.

The innate immune system in demyelinating disease

Demyelinating diseases such as multiple sclerosis are chronic inflammatory autoimmune diseases with a heterogeneous clinical presentation and course. Both the adaptive and the innate immune systems have been suggested to contribute to their pathogenesis and recovery. In this review, we discuss the role of the innate immune system in mediating demyelinating diseases. In particular, we provide an overview of the anti-inflammatory or pro-inflammatory functions of dendritic cells, mast cells, natural killer (NK) cells, NK-T cells, γδ T cells, microglial cells, and astrocytes. We emphasize the interaction of astroctyes with the immune system and how this interaction relates to the demyelinating pathologies. Given the pivotal role of the innate immune system, it is possible that targeting these cells may provide an effective therapeutic approach for demyelinating diseases.

The role of TIM-containing molecules in airway disease and their potential as therapeutic targets

T cell immunoglobulin and mucin-domain (TIM)-containing molecules have emerged as promising therapeutic targets to correct abnormal immune function in several autoimmune and chronic inflammatory conditions. Despite the initial discovery linking TIM-containing molecules and the airway hyperreactivity regulatory locus in mice, there is a paucity of studies on the function of TIM-containing molecules in lung inflammatory disease. Initially, studies were limited to mice models of asthma. More recently however, TIM-containing molecules have been implicated in an ever-expanding list of airway conditions that includes pneumonia, tuberculosis, influenza, sarcoidosis, lung cancer, and cystic fibrosis. This present review discusses the role of TIM-containing molecules and their ligands in the lung, as well as their potential as therapeutic targets in airway disease.

Tim-3 negatively regulates cytotoxicity in exhausted CD8+ T cells in HIV infection

Cytotoxic CD8⁺ T cells (CTLs) contain virus infections through the release of granules containing both perforin and granzymes. T cell ‘exhaustion’ is a hallmark of chronic persistent viral infections including HIV. The inhibitory regulatory molecule, T cell Immunoglobulin and Mucin domain containing 3 (Tim-3) is induced on HIV-specific T cells in chronic progressive infection. These Tim-3 expressing T cells are dysfunctional in terms of their capacities to proliferate or to produce cytokines. In this study, we evaluated the effect of Tim-3 expression on the cytotoxic capabilities of CD8⁺ T cells in the context of HIV infection. We investigated the cytotoxic capacity of Tim-3 expressing T cells by examining 1) the ability of Tim-3⁺ CD8⁺ T cells to make perforin and 2) the direct ability of Tim-3⁺ CD8⁺ T cells to kill autologous HIV infected CD4⁺ target cells. Surprisingly, Tim-3⁺ CD8⁺ T cells maintain higher levels of perforin, which was mainly in a granule-associated (stored) conformation, as well as express high levels of T-bet. However, these cells were also defective in their ability to degranulate. Blocking the Tim-3 signalling pathway enhanced the cytotoxic capabilities of HIV specific CD8⁺ T cells from chronic progressors by increasing; a) their degranulation capacity, b) their ability to release perforin, c) their ability to target activated granzyme B to HIV antigen expressing CD4⁺ T cells and d) their ability to suppress HIV infection of CD4⁺ T cells. In this latter effect, blocking the Tim-3 pathway enhances the cytotoxcity of CD8⁺ T cells from chronic progressors to the level very close to that of T cells from viral controllers. Thus, the Tim-3 receptor, in addition to acting as a terminator for cytokine producing and proliferative functions of CTLs, can also down-regulate the CD8⁺ T cell cytotoxic function through inhibition of degranulation and perforin and granzyme secretion.

T cell immunoglobulin- and mucin-domain-containing molecule 3 gene polymorphisms and susceptibility to pancreatic cancer

T cell immunoglobulin- and mucin-domain-containing molecule 3 (TIM-3) is a novel transmembrane protein that is involved in the regulation of T-helper 1 cell-mediated immunity. Studies have shown that polymorphisms in TIM-3 gene can be associated with various diseases. Here, we investigated the correlation of TIM-3 polymorphisms with susceptibility to pancreatic cancer in the Chinese population. Three polymorphisms in TIM-3 gene (-1516G/T, -574G/T, and +4259T/G) were identified by polymerase chain reaction-restriction fragment length polymorphism in 306 pancreatic patients and 408 healthy controls. Results showed that the prevalence of +4259TG genotype and +4259G allele were significantly increased in the pancreatic cancer cases than in controls [odds ratio (OR) = 2.82, 95 % confidence interval (CI), 1.45-5.48, p = 0.0015, and OR = 2.74, 95 % CI, 1.42-2.94, p = 0.0017]. In addition, when analyzing the TIM-3 polymorphisms with different clinical parameters in pancreatic cancer patients, the cases with vascular infiltration had higher numbers of +4259T/G polymorphism than those without vascular infiltration (OR = 3.07, 95 % CI, 1.41-6.68, p = 0.003). These results suggested polymorphisms in TIM-3 gene could be new risk factors for the development of pancreatic cancer.

Galectins and their ligands: negative regulators of anti-tumor immunity

Cytotoxic CD8(+) T cells are major players of anti-tumor immune responses, as their functional activity can limit tumor growth and progression. Data show that cytotoxic T cells efficiently control the proliferation of tumor cells through major histocompatibility complex class I-mediated mechanisms; nevertheless, the presence of tumor-infiltrating CD8(+) T cells in lesional tissue does not always correlate with better prognosis and increased survival of cancer patients. Similarly, adoptive transfer of tumor-specific cytotoxic T cells has only shown marginal improvement in life spans of patients with metastatic disease. In this report, we discuss experimental evidence showing that expression of tumor-derived galectins, galectin (Gal)-1, Gal-3 and Gal-9, and concomitant presence of their ligands on the surface of anti-tumor immunocytes directly compromise anti-tumor CD8(+) T cell immune responses and, perhaps, undermine the promise of adoptive CD8(+) T cell immunotherapy. Furthermore, we describe novel strategies designed to counteract Gal-1-, Gal-3- and Gal-9-mediated effects and highlight their targeting potential for creating more effective anti-tumor immune responses. We believe that Gal and their ligands represent an efficacious targeted molecular paradigm that warrants clinical evaluation.

Positive and negative regulation of cellular immune responses in physiologic conditions and diseases

The immune system has evolved to allow robust responses against pathogens while avoiding autoimmunity. This is notably enabled by stimulatory and inhibitory signals which contribute to the regulation of immune responses. In the presence of a pathogen, a specific and effective immune response must be induced and this leads to antigen-specific T-cell proliferation, cytokines production, and induction of T-cell differentiation toward an effector phenotype. After clearance or control of the pathogen, the effector immune response must be terminated in order to avoid tissue damage and chronic inflammation and this process involves coinhibitory molecules. When the immune system fails to eliminate or control the pathogen, continuous stimulation of T cells prevents the full contraction and leads to the functional exhaustion of effector T cells. Several evidences both in vitro and in vivo suggest that this anergic state can be reverted by blocking the interactions between coinhibitory molecules and their ligands. The potential to revert exhausted or inactivated T-cell responses following selective blocking of their function made these markers interesting targets for therapeutic interventions in patients with persistent viral infections or cancer.

T lymphocyte surface expression of exhaustion markers as biomarkers of the efficacy of chemotherapy for tuberculosis

Predictive biomarkers illustrating the effectiveness of chemotherapeutic regimens for tuberculosis still remain elusive. To date, most are predicated on assays using sputum or serum; as a result, if not predictive, treatment failure in patients may not be evident for some time. We report here the results of a simple screening study in which T cell surface markers were examined in mice infected with Mycobacterium tuberculosis and then treated with drugs. These studies identified certain markers, the exhaustion markers PD-1 and TIM-3, as well as the marker KLRG-1, particularly on CD8 T cells, that changed in concert with reduction of the bacterial load in the lungs. While there is no guarantee these changes would also be seen on T cells in the blood, this approach should be further investigated.