Preferential involvement of Tim-3 in the regulation of hepatic CD8+ T cells in murine acute graft-versus-host disease

Two machine learning-derived nomogram for predicting the occurrence and severity of acute graft-versus-host disease: a retrospective study based on serum biomarkers

Background

Acute graft-versus-host disease (aGVHD) is a common complication after allogeneic hematopoietic cell transplantation (allo-HSCT), with high morbidity and mortality. Although glucocorticoids are the standard treatment, only half of patients achieve complete remission. Thus, there is an urgent need to screen biomarkers for the diagnosis of aGVHD to assist in the identification of individuals at risk of aGVHD. This study was to construct prediction models for the occurrence and severity of aGVHD using two machine learning algorithms based on serum biochemical data.

Methods

Clinical data of 120 patients with hematological diseases who received allo-HSCT were retrospectively analyzed. Seventy-six patients developed aGVHD, including 56 grade I/II and 20 grade III/IV. First, 15 serum biochemical indicators were considered as potential risk factors, and the differences in the levels of indicators between non-aGVHD and aGVHD were observed, followed by evaluation of the diagnostic property. Subsequently, to develop the prediction models for the occurrence and severity of aGVHD, LASSO and random forest (RF) analyses were performed with experimental indicators. Finally, Venn diagram analysis was utilized to obtain shared biomarkers in the two algorithms to construct the nomogram. The model performance was measured by calibration curves. Internal and external validations were performed based on risk score models and ROC curve analyses.

Results

Total 12 of 15 indicators exhibited significant differences between the aGVHD and non-aGVHD groups, with AUC values > 0.75. In machine learning analysis, eight features (LAG-3, TLR-2, PD-L1, IP-10, elafin, REG-3α, ST2, TIM3) and seven variables (LAG-3, TLR-2, PD-1, Flt_3, IL-9, elafin, TIM3) were selected to distinguish aGVHD vs. non-aGVHD as well as grade I/II vs. III/IV, respectively. Further, the corresponding nomogram models were established and calibration curves showed that prediction was in good agreement with the actual probability. Biomarker-based risk score model was constructed, which obtained AUC value >0.89 in internal and external datasets.

Conclusion

Clinical variables screened through learning algorithm can predict the risk and severity of aGVHD. Our findings may help clinicians develop more personalized and reasonable management strategies.

Immune checkpoint inhibitors in infectious disease

Following success in cancer immunotherapy, immune checkpoint blockade is emerging as an exciting potential treatment for some infectious diseases, specifically two chronic viral infections, HIV and hepatitis B. Here, we will discuss the function of immune checkpoints, their role in infectious disease pathology, and the ability of immune checkpoint blockade to reinvigorate the immune response. We focus on blockade of programmed cell death 1 (PD-1) to induce durable immune-mediated control of HIV, given that anti-PD-1 can restore function to exhausted HIV-specific T cells and also reverse HIV latency, a long-lived form of viral infection. We highlight several key studies and future directions of research in relation to anti-PD-1 and HIV persistence from our group, including the impact of immune checkpoint blockade on the establishment (AIDS, 2018, 32, 1491), maintenance (PLoS Pathog, 2016, 12, e1005761; J Infect Dis, 2017, 215, 911; Cell Rep Med, 2022, 3, 100766) and reversal of HIV latency (Nat Commun, 2019, 10, 814; J Immunol, 2020, 204, 1242), enhancement of HIV-specific T cell function (J Immunol, 2022, 208, 54; iScience, 2023, 26, 108165), and investigating the effects of anti-PD-1 and anti-CTLA-4 in vivo in people with HIV on ART with cancer (Sci Transl Med, 2022, 14, eabl3836; AIDS, 2021, 35, 1631; Clin Infect Dis, 2021, 73, e1973). Our future work will focus on the impact of anti-PD-1 in vivo in people with HIV on ART without cancer and potential combinations of anti-PD-1 with other interventions, including therapeutic vaccines or antibodies and less toxic immune checkpoint blockers.

Novel Immune Checkpoint Inhibitor Targets in Advanced or Metastatic Renal Cell Carcinoma: State of the Art and Future Perspectives

Immune checkpoint inhibitors (ICI) have become the cornerstone of treatment in renal cell carcinoma (RCC), for both metastatic disease and in an adjuvant setting. However, an adaptive resistance from cancer cells may arise during ICI treatment, therefore many studies are focusing on additional immune checkpoint inhibitor pathways. Promising targets of immunotherapeutic agents under investigation include T cell immunoglobulin and ITIM domain (TIGIT), immunoglobulin-like transcript 4 (ILT4), lymphocyte activation gene-3 (LAG-3), vaccines, T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3), and chimeric antigen receptor (CAR) T cells. In this review of the literature, we recollect the current knowledge of the novel treatment strategies in the field of immunotherapy that are being investigated in RCC and analyze their mechanism of action, their activity and the clinical studies that are currently underway.

Inhibition of the TIM-1 and -3 signaling pathway ameliorates disease in a murine model of rheumatoid arthritis

Members of the T-cell immunoglobulin and mucin (TIM) family, which is crucial for T-cell function, are implicated in autoimmunity. TIM-1 and -3 play distinct roles in autoimmunity, with TIM-1 acting as a costimulatory molecule and TIM-3 regulating Th1 responses. We investigated the therapeutic potential of anti-TIM-1 (RMT1-10) and anti-TIM-3 (RMT3-23) antibodies in an autoimmune arthritis model. Zymosan A was used to induce arthritis in female SKG mice. The arthritis scores, histology, mRNA expression, cytokine levels, micro-computed tomography, and flow cytometry results were obtained. The application of RMT1-10 reduced the arthritis scores, histological damage, and CD4+ T-cell infiltrations, and it suppressed interleukin (IL)-6 and -17A and reduced TIM-3 mRNA expressions. RMT3-23 also lowered arthritis severity, improved histology, and reduced serum levels of tumor necrosis factor (TNF)-α and IL-17A. RMT3-23 inhibited intracellular TNF-α and IL-6 and early apoptosis. An amelioration of autoimmune arthritis was achieved by blocking the TIM-1 and -3 signaling pathways via RMT1-10 and RMT3-23 administration, leading to a widespread decrease in inflammatory cytokines. Both antibodies exhibited therapeutic effects, suggesting TIM-1 and -3 as potential targets for rheumatoid arthritis.

Efferocytosis in dendritic cells: an overlooked immunoregulatory process

Efferocytosis, the process of engulfing and removing apoptotic cells, plays an essential role in preserving tissue health and averting undue inflammation. While macrophages are primarily known for this task, dendritic cells (DCs) also play a significant role. This review delves into the unique contributions of various DC subsets to efferocytosis, highlighting the distinctions in how DCs and macrophages recognize and handle apoptotic cells. It further explores how efferocytosis influences DC maturation, thereby affecting immune tolerance. This underscores the pivotal role of DCs in orchestrating immune responses and sustaining immune equilibrium, providing new insights into their function in immune regulation.

Emerging strategies for treating autoimmune disease with genetically modified dendritic cells

Gene editing of living cells has become a crucial tool in medical research, enabling scientists to address fundamental biological questions and develop novel strategies for disease treatment. This technology has particularly revolutionized adoptive transfer cell therapy products, leading to significant advancements in tumor treatment and offering promising outcomes in managing transplant rejection, autoimmune disorders, and inflammatory diseases. While recent clinical trials have demonstrated the safety of tolerogenic dendritic cell (TolDC) immunotherapy, concerns remain regarding its effectiveness. This review aims to discuss the application of gene editing techniques to enhance the tolerance function of dendritic cells (DCs), with a particular focus on preclinical strategies that are currently being investigated to optimize the tolerogenic phenotype and function of DCs. We explore potential approaches for in vitro generation of TolDCs and provide an overview of emerging strategies for modifying DCs. Additionally, we highlight the primary challenges hindering the clinical adoption of TolDC therapeutics and propose future research directions in this field.

Unlocking protein-based biomarker potential for graft-versus-host disease following allogenic hematopoietic stem cell transplants

Despite the numerous advantages of allogeneic hematopoietic stem cell transplants (allo-HSCT), there exists a notable association with risks, particularly during the preconditioning period and predominantly post-intervention, exemplified by the occurrence of graft-versus-host disease (GVHD). Risk stratification prior to symptom manifestation, along with precise diagnosis and prognosis, relies heavily on clinical features. A critical imperative is the development of tools capable of early identification and effective management of patients undergoing allo-HSCT. A promising avenue in this pursuit is the utilization of proteomics-based biomarkers obtained from non-invasive biospecimens. This review comprehensively outlines the application of proteomics and proteomics-based biomarkers in GVHD patients. It delves into both single protein markers and protein panels, offering insights into their relevance in acute and chronic GVHD. Furthermore, the review provides a detailed examination of the site-specific involvement of GVHD. In summary, this article explores the potential of proteomics as a tool for timely and accurate intervention in the context of GVHD following allo-HSCT.

Galectin-9 alleviates acute graft-versus-host disease after haplo-hematopoietic stem cell transplantation by regulating regulatory T cell/effector T cell imbalance

BACKGROUND

Acute graft-versus-host disease (aGVHD) arises from the imbalance of host T cells. Galectin-9 negatively regulates CD4 effector T cell (Th1 and Th17) function by binding to Tim-3. However, the relationship between Galectin-9/Tim-3 and CD4+ T subsets in patients with aGVHD after Haplo-HSCT (haploidentical peripheral blood hematopoietic stem cell transplantation) has not been fully elucidated. Here, we investigated the role of Galectin-9 and CD4+ T subsets in aGVHD after haplo-HSCT.

METHODS

Forty-two patients underwent Haplo-HSCT (26 without aGVHD and 16 with aGVHD), and 20 healthy controls were included. The concentrations of Galectin-9, interferon-gamma (IFN-γ), interleukin (IL)-4, transforming growth factor (TGF)-β, and IL-17 in the serum and culture supernatant were measured using enzyme-linked immunosorbent assay or cytometric bead array. The expression levels of Galectin-9, PI3K, p-PI3K, and p-mTOR protein were detected by western blot analysis. Flow cytometry was used to analyze the proportions of CD4+ T cell subsets. Bioinformatics analysis was performed.

RESULTS

In patients with aGVHD, regulatory T (Treg) cells and Galectin-9 decreased, and the Th1, Th17, and Treg cells were significantly imbalanced. Moreover, Treg and Galectin-9 were rapidly reconstituted in the early stage of patients without aGVHD after Haplo-HSCT, but Th17 cells were reconstituted slowly. Furthermore, Tim-3 upregulation on Th17 and Th1 cells was associated with excessive activation of the PI3K/AKT pathway in patients with aGVHD. Specifically, in vitro treatment with Galectin-9 reduced IFN-γ and IL-17 production while augmenting TGF-β secretion. Bioinformatics analysis suggested the potential involvement of the PI3K/AKT/mTOR pathway in aGVHD. Mechanistically, exogenous Galectin-9 was found to mitigate aGVHD by restoring the Treg/Teffs (effector T cells) balance and suppressing PI3K.

CONCLUSION

Galectin-9 may ameliorate aGVHD after haplo-HSCT by modulating Treg/Teffs balance and regulating the PI3K/AKT/mTOR pathway. Targeting Galectin-9 may hold potential value for the treatment of aGVHD.

The level of Tim-3+CD8+ T cells can serve as a potential marker for evaluating the severity of acute graft-versus-host disease after haplo-PBSCT

Early and accurate diagnosis of acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation is crucial for the prognosis of patients. This study identified a potential biomarker for the severity of aGVHD after human leukocyte antigen (HLA)-haploidentical peripheral blood hematopoietic stem cell transplantation (haplo-PBSCT). We included 20 healthy subjects and 57 patients who underwent haplo-PBSCT. Of these patients, 22 developed aGVHD after haplo-PBSCT. The results showed that patients with aGVHD had significantly increased levels of Tim-3+/Perforin+/Granzyme B+CD8+ T cells, but significantly decreased Galectin-9. The differences in Galectin-9 and Tim-3+/Granzyme B+CD8+ T cells between grade I-II aGVHD and III-IV aGVHD were also significant. In vitro, the apoptosis of CD8+ T cells from aGVHD patients was significantly increased after Tim-3/Galectin-9 pathway activation, which decreased Granzyme B secretion. As revealed by univariate analysis, the level of Tim-3+CD8+ T cells was a risk factor for severe aGVHD. ROC analysis demonstrated that high levels of Tim-3+CD8+ T cells had a significant diagnostic value for severe aGVHD, with an area under the curve of 0.854 and cut-off value of 14.155%. In conclusion, the binding of Tim-3 with exogenous Galectin-9 can promote apoptosis of CD8+ T cells and affect the secretion of Granzyme B. Tim-3+CD8+ T cells have the potential to serve as immunological markers for assessing the severity of aGVHD after haplo-PBSCT and identifying patients at a higher risk for severe aGVHD.

Withaferin-A alleviates acute graft versus host disease without compromising graft versus leukemia effect

Acute graft versus host disease (aGvHD) contributes to a significant proportion of non-relapse mortality and morbidity in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). Withaferin-A (WA), a phytomolecule obtained from Withania somnifera (Ashwagandha), is known to have anti-inflammatory, anti-proliferative and immunomodulatory properties. The efficacy of WA for the prevention and treatment of aGvHD was evaluated using a murine model of alloHSCT. Prophylactic administration of WA to mice mitigated the clinical symptoms of aGvHD and improved survival significantly compared to the GvHD control [HR = 0.07 (0.01-0.35); P < 0.001]. Furthermore, WA group had better overall survival compared to standard prophylactic regimen of CSA + MTX [HR = 0.19 (0.03-1.1), P < 0.05]. At the same time, WA did not compromise the beneficial GvL effect. In addition, WA administered to animals after the onset of aGvHD could reverse the clinical severity and improved survival, thus establishing its therapeutic potential. Our findings suggest that WA reduced the systemic levels of Th1, Th2 and Th17 inflammatory cytokine and increased the anti-inflammatory cytokine IL-10 levels significantly (P < 0.05). WA also inhibited lymphocytes migration to gut, liver, skin and lung and protected these organs from damage. Ex-vivo, WA inhibited proliferation of human peripheral blood mononuclear cells (hPBMCs), modulated immune cell phenotype and decreased cytokine release. In addition, WA inhibited pJAK2 and pSTAT3 protein levels in mouse splenocytes and hPBMCs. In conclusion, our study demonstrates the utility of WA for the prevention and treatment of aGvHD, which should be further evaluated in a clinical setting.

Tim-3 blockade enhances the clearance of Chlamydia psittaci in the lung by promoting a cell-mediated immune response

Chlamydia psittaci is remarkable at disrupting immunity and thus poses a great risk to the animal industry and public health. Immune inhibitory molecule upregulation and the accumulation of specialized cells play key roles in chlamydial clearance. It is clear that the T-cell immunoglobulin and mucin domain protein 3 receptor (Tim-3) can regulate effector T cells in infectious disease. However, the immunomodulatory effect of Tim-3 in C. psittaci infection remains unknown. Thus, the expression of Tim-3 in effector T cells and its immune regulatory function during C. psittaci infection were investigated. The level of Tim-3 on CD4⁺ and CD8⁺ T cells was meaningfully higher in C. psittaci-infected mice. Blockade of Tim-3 signaling by anti-Tim-3 antibody showed accelerated C. psittaci clearance and less pathological changes in the lung than isotype immunoglobulin treatment. Furthermore, treatment with anti-Tim-3 antibody greatly enhanced the levels of IFN-γ and interleukin (IL)-22/IL-17, which were correlated with an improved Th1- and Th17-mediated immune response, and decreased IL-10, which were related with a decreased Treg immune response. In conclusion, Tim-3 expression in effector T cells negatively regulates Th1 and Th17 immune responses against C. psittaci respiratory infection.

Biomarkers for early complications post hematopoietic cell transplantation: Insights and challenges

Hematopoietic cell transplantation is an established curative treatment option for various hematological malignant, and non-malignant diseases. However, the success of HCT is still limited by life-threatening early complications post-HCT, such as Graft Versus Host Disease (GVHD), Sinusoidal Obstruction Syndrome (SOS), and transplant-associated microangiopathy, to name a few. A decade of research in the discovery and validation of novel blood-based biomarkers aims to manage these early complications by using them for diagnosis or prognosis. Advances in this field have also led to predictive biomarkers to identify patients' likelihood of response to therapy. Although biomarkers have been extensively evaluated for different complications, these are yet to be used in routine clinical practice. This review provides a detailed summary of various biomarkers for individual early complications post-HCT, their discovery, validation, ongoing clinical trials, and their limitations. Furthermore, this review also provides insights into the biology of biomarkers and the challenge of obtaining a universal cut-off value for biomarkers.

Assessment of systemic and gastrointestinal tissue damage biomarkers for GVHD risk stratification

Two biomarker algorithms that include only systemic inflammation biomarkers predicted response to steroid treatment but not 6-month NRM.

Two biomarker algorithms that include ≥1 biomarker of GI tissue damage predicted both response to treatment and 6-month NRM.

We used a rigorous PRoBE (prospective-specimen collection, retrospective-blinded-evaluation) study design to compare the ability of biomarkers of systemic inflammation and biomarkers of gastrointestinal (GI) tissue damage to predict response to corticosteroid treatment, the incidence of clinically severe disease, 6-month nonrelapse mortality (NRM), and overall survival in patients with acute graft-versus-host disease (GVHD). We prospectively collected serum samples of newly diagnosed GVHD patients (n = 730) from 19 centers, divided them into training (n = 352) and validation (n = 378) cohorts, and measured TNFR1, TIM3, IL6, ST2, and REG3α via enzyme-linked immunosorbent assay. Performances of the 4 strongest algorithms from the training cohort (TNFR1 + TIM3, TNFR1 + ST2, TNFR1 + REG3α, and ST2 + REG3α) were evaluated in the validation cohort. The algorithm that included only biomarkers of systemic inflammation (TNFR1 + TIM3) had a significantly smaller area under the curve (AUC; 0.57) than the AUCs of algorithms that contained ≥1 GI damage biomarker (TNFR1 + ST2, 0.70; TNFR1 + REG3α, 0.73; ST2 + REG3α, 0.79; all P < .001). All 4 algorithms were able to predict short-term outcomes such as response to systemic corticosteroids and severe GVHD, but the inclusion of a GI damage biomarker was needed to predict long-term outcomes such as 6-month NRM and survival. The algorithm that included 2 GI damage biomarkers was the most accurate of the 4 algorithms for all endpoints.

Soluble T Cell Immunoglobulin and Mucin Domain-3 (sTIM-3) Predict Graft-Versus-Host Disease (GVHD) in Iranian Allogeneic Hematopoietic Stem Cell Transplantation

Background: T cell immunoglobulin and mucin domain-3 (TIM-3) is an immune-checkpoint molecule that is upregulated following allogeneic immune responses and could play an important role in the development and pathogenesis of graft-versus-host disease (GVHD). The soluble form of TIM-3 (sTIM-3) is increased following the upregulation of membranous TIM-3. Objectives: The aim of this study was to evaluate the association between plasma level of sTIM-3 and acute GVHD (aGVHD) incidence in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: Blood samples were collected from 42 allo-HSCT patients and 20 healthy individuals 2 weeks after allo-HSCT. The plasma level of sTIM-3 was measured using enzyme-linked immunosorbent assay (ELISA). The clinical and demographic data of patients were collected from the clinical documents. Data analysis was evaluated using student t-test and one-way ANOVA tests. P-values less than 0.05 were assumed statistically significant. Results: Among 18 (42.8%) patients with aGVHD symptoms, 10 (23.8%) had severe GVHD and 8 (19%) experienced mild GVHD. Plasma sTIM-3 levels at day +14 were significantly higher in patients who developed aGVHD compared to allo-HSCT patients without GVHD and also the healthy control individuals (P-value = 0.015 and < 0.001). Among the aGVHD patients, the sTIM-3 levels in those with severe GVHD were approximately 2.5 times higher than those with mild GVHD (P-value < 0.001). Conclusions: We have identified a high plasma level of sTIM-3 as a valuable biomarker in predicting the development of acute GVHD, especially severe aGVHD in allo-HSCT patients.

The role of phosphatidylserine on the membrane in immunity and blood coagulation

The negatively charged aminophospholipid, phosphatidylserine (PtdSer), is located in the inner leaflet of the plasma membrane in normal cells, and may be exposed to the outer leaflet under some immune and blood coagulation processes. Meanwhile, Ptdser exposed to apoptotic cells can be recognized and eliminated by various immune cells, whereas on the surface of activated platelets Ptdser interacts with coagulation factors prompting enhanced production of thrombin which significantly facilitates blood coagulation. In the case where PtdSer fails in exposure or mistakenly occurs, there are occurrences of certain immunological and haematological diseases, such as the Scott syndrome and Systemic lupus erythematosus. Besides, viruses (e.g., Human Immunodeficiency Virus (HIV), Ebola virus (EBOV)) can invade host cells through binding the exposed PtdSer. Most recently, the Corona Virus Disease 2019 (COVID-19) has been similarly linked to PtdSer or its receptors. Therefore, it is essential to comprehensively understand PtdSer and its functional characteristics. Therefore, this review summarizes Ptdser, its eversion mechanism; interaction mechanism, particularly with its immune receptors and coagulation factors; recognition sites; and its function in immune and blood processes. This review illustrates the potential aspects for the underlying pathogenic mechanism of PtdSer-related diseases, and the discovery of new therapeutic strategies as well.

Pseudomonas aeruginosa outer membrane vesicles ameliorates lung ischemia-reperfusion injury by regulating the balance of regulatory T cells and Th17 cells through Tim-3 and TLR4/NF-κB pathway

OBJECTIVE

Regulatory T cells (Tregs) and T helper (Th) 17 cells are two subsets of CD4 + T cells with opposite effects which play a crucial role in the pathogenesis of lung injury. In this study, we aim to investigate the protective effect of Pseudomonas aeruginosa outer membrane vesicles (OMVs) preconditioning on lung ischemia-reperfusion (I/R) injury and potential mechanisms.

METHODS

Pathogen-free C57BL/6 mice were randomly divided into four groups: control, Control + OMVs, I/R and I/R + OMVs groups. Bronchoalveolar lavage fluid (BALF), serum, and lung tissues were collected and analyzed for pathophysiology and immune mechanism.

RESULTS

OMVs not only attenuated tissue injury and respiratory physiologic function but also mediated the downregulation of lung wet-to-dry weight ratio and the reduction of total protein concentration. The numbers of total cells, macrophages, neutrophils, and lymphocytes were markedly decreased in the I/R mice following OMVs preconditioning. OMVs also decreased inflammatory cytokines associated with CD4 + T cells in both BALF and serum. In addition, the level of Tregs and its transcription factor forkhead box P3 (Foxp3) were significantly increased, while the level of Th17 cells and its transcription factor retinoid-related orphan receptor γ (RORγt) were significantly decreased following OMVs preconditioning. In the process of exploring the underlying protection mechanisms of OMVs, we found that OMVs preconditioning significantly reduced protein expression of Toll-like receptor 4 (TLR4), which in turn not only inactivated myeloid differentiation factor 88 (MyD88) and Phosphorylated nuclear factor kappa B (p-NF-κB), but also simultaneously increased the levels of T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3).

CONCLUSIONS

These results suggest that OMVs preconditioning may ameliorate lung I/R injury by regulating the balance of Tregs and Th17 cells through Tim-3 and TLR4/NF-κB pathway.

TIM-3: An update on immunotherapy

T cell immunoglobulin and mucin domain 3 (TIM-3) was originally found to be expressed on the surface of Th1 cells, acting as a negative regulator and binding to the ligand galectin-9 to mediate Th1 cell the apoptosis. Recent studies have shown that TIM-3 is also expressed on other immune cells, such as macrophages, dendritic cells, and monocytes. In addition, TIM-3 ligands also include Psdter, High Mobility Group Box 1 (HMGB1) and Carcinoembryonic antigen associated cell adhesion molecules (Ceacam-1), which have different effects upon biding to different ligands on immune cells. Studies have shown that TIM-3 plays an important role in autoimmune diseases, chronic viral infections and tumors. A large amount of experimental data supports TIM-3 as an immune checkpoint, and targeting TIM-3 is a promising treatment method in current immunotherapy, especially the new combination of other immune checkpoint blockers. In this review, we summarize the role of TIM-3 in different diseases and its possible signaling pathway mechanisms, providing new insights for better breakthrough immunotherapy.

Role of Tim-3 in regulating tumorigenesis, inflammation, and antitumor immunity therapy

Over the past decade, cancer immunotherapy, such as immune checkpoint inhibitors (ICRs), has attained considerable progresses in clinical practice. T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) act as next ICRs, and originally function as a co-inhibitory receptor expressed on interferon (IFN)-γ producing CD4+ and CD8+ T-cells. Furthermore, Tim-3 has also been found to express on innate immune cells and several types of tumors, signifying the pivotal role that Tim-3 plays in chronic viral infections and cancer. In addition, Tim-3 and multiple ICRs are concurrently expressed and regulated on dysfunctional or exhausted T-cells, leading to improved antitumor immune responses in preclinical or clinical cancer therapy through co-blockade of Tim-3 and other ICRs such as programmed cell death-1 (PD-1). In this review, the biological characteristics of Tim-3 and the function of Tim-3 in regulating tumorigenesis and inflammation have been summarized. The usage of a single blockade of Tim-3 or in combination with multiple immunotherapy regimens have drawn attention to antitumor potential as a target for immunotherapy.

Galectin-9 is required for endometrial regenerative cells to induce long-term cardiac allograft survival in mice

Background

Endometrial regenerative cells (ERCs), a novel type of mesenchymal-like stem cells, were identified as an attractive candidate for immunoregulation and induction of cardiac allograft tolerance. However, the underlying mechanisms of ERCs in immune regulation still remain largely unclear. The present study is designed to determine whether the expression of Galectin-9 (Gal-9), a soluble tandem-repeat member of the galectin family, is crucial for ERC-based immunomodulation.

Methods

In this study, we measured Gal-9 expression on ERCs and then co-cultured Gal-9-ERCs, ERCs, and ERCs+lactose (Gal-9 blocker) with activated C57BL/6-derived splenocytes. Furthermore, we performed mouse heart transplantation between BALB/c (H-2^d) donor and C57BL/6 (H-2^b) recipient. ERCs were administrated 24 h after the surgery, either alone or in combination with rapamycin.

Results

Our data demonstrate that ERCs express Gal-9, and this expression is increased by IFN-γ stimulation in a dose-dependent manner. Moreover, both in vitro and in vivo results show that Gal-9-ERC-mediated therapy significantly suppressed Th1 and Th17 cell response, inhibited CD8⁺ T cell proliferation, abrogated B cell activation, decreased donor-specific antibody production, and enhanced the Treg population. The therapeutic effect of ERCs was further verified by their roles in prolonging cardiac allograft survival and alleviating graft pathological changes.

Conclusions

Taken together, these data indicate that Gal-9 is required for ERC-mediated immunomodulation and prevention of allograft rejection.

Study of T-cell immunoglobulin and mucin domain-3 expression profile in peripheral blood and bone marrow of human acute lymphoblastic leukemia patients

Background

Acute lymphoblastic leukemia (ALL) is a malignancy with aggressive tumors of immature lymphocytes. T-cell immunoglobulin and mucin-domain 3 (TIM-3) is a Type I transmembrane glycoprotein which is involved in cell proliferation. The objective of this research is to determine the TIM-3 expression in peripheral blood (PB) and bone marrow (BM) of 80 samples of normal and ALL patients.

Materials and Methods

The amount of mRNA and protein of TIM-3 measured in the BM and PB the mononuclear layer of samples by real-time polymerase chain reaction and Western blotting.

Results

Our findings indicated that relative mRNA expression of TIM-3 in PB and BM of the mononuclear layer of ALL patients was 1.7 and 5 times higher than normals, respectively. We also reported that the protein level of TIM-3 in mononuclear cells of ALL patients was 3.2-fold in BM and two-fold in PB more than normals.

Conclusion

In conclusion, this study shows that TIM-3 increases in ALL patients, thus the expression of TIM-3 in tumor cells may be considered as a potential predictive factor in ALL patients, which needs to be explored in future.

Increased Galectin-9 expression, a prognostic biomarker of aGVHD, regulates the immune response through the Galectin-9 induced MDSC pathway after allogeneic hematopoietic stem cell transplantation

Galectin-9 (Gal-9) is a β-galactoside-binding soluble lectin family member that exerts its primary biological functions via specific glycoconjugate interactions. Gal-9 expression is closely related to tumor occurrence, development, metastasis and prognosis. In transplant immunology, a high level of Gal-9 expression has been shown to markedly reduce the severity of acute graft rejection and effectively prolong survival time in organ and bone marrow transplantation (BMT) models. The main mechanism of Gal-9-mediated immunoregulation involves the Tim-3/Gal-9 axis in T cells. However, myeloid-derived suppressor cell (MDSC) accumulation in transgenic mice with persistently high Gal-9 expression was observed in a model of lung inflammation, indicating that a potential immunosuppressive mechanism distinct from the Gal-9/Tim-3 axis might exist. In the present study, increased Gal-9 expression and MDSC frequencies before acute graft-versus-host disease (aGVHD) onset were observed in patients who developed aGVHD. Patients with higher Gal-9 expression (≥14.8417 ng/ml) exhibited reduced overall survival and increased cumulative incidences of GVHD at +100 day. We considered the elevated Gal-9 expression before aGVHD onset a secondary inflammatory response. This increase might be part of a negative feedback pathway corresponding to aGVHD pathogenesis. Additionally, a high Gal-9 concentration induced MDSC proliferation in vivo and in vitro. Gal-9-induced MDSCs (G9-MDSCs) suppressed T cell proliferation and activation. An infusion of G9-MDSCs into a graft contributed to the successful control of severe aGVHD and long-term survival in an allogeneic (allo)-BMT mouse model. Thus, we speculated that increased Gal-9 expression after allo-hematopoietic stem cell transplantation is a potential prognostic biomarker of aGVHD. The Gal-9-associated immunosuppressive effects on aGVHD development might occurr through G9-MDSCs and were independent of the Gal-9/Tim-3 axis.

ImmunoPET Imaging of TIM-3 in Murine Melanoma Models

T cell immunoglobulin and mucin domain-containing-3 (TIM-3) is an immune checkpoint expressed mainly on CD4+ and CD8+ T cells. In addition to negatively regulating inflammatory T cell function, TIM-3 is a promising immunotherapy target. Herein, the aim is to develop an immuno-positron emission tomography (immunoPET) probe for noninvasively characterizing TIM-3 expression. Flow cytometry is used to detect the expression levels of TIM-3 in B16F10 cells. RMT3-23, a rat antimouse TIM-3-specific monoclonal antibody, is radiolabeled with 64Cu and the performance of 64Cu-NOTA-RMT3-23 is interrogated by immunoPET in murine melanoma models before and after radiation therapies. Biodistribution and immunofluorescent staining studies are carried out after the immunoPET imaging studies. TIM-3 is negatively expressed in B16F10 cells, and its expression is not induced by radiation therapies. ImmunoPET imaging with 64Cu-NOTA-RMT3-23 precisely tracks the unique distribution of TIM-3-positive lymphocytes in immunocompetent melanoma models, and tumor uptake of the radiotracer is not affected by either single-dose or fractionated radiation therapies. The 64Cu-NOTA-RMT3-23 immunoPET imaging results are further mirrored by the immunofluorescent staining studies. These results demonstrate the feasibility of 64Cu-NOTA-RMT3-23 immunoPET in tracking TIM-3 and highlight a new opportunity to optimize TIM-3-targeted immunotherapies with this novel imaging strategy.

Cross-regulation by TLR4 and T cell Ig mucin-3 determines severity of liver injury in a CCl4-induced mouse model

Acute liver injury is a common pathological basis for a variety of acute liver diseases in the clinic, which can eventually lead to liver fibrosis and even liver failure. In this study, we found that T cell Ig and mucin domain protein 3 (Tim-3) and TLR4 receptors play important roles in CCl4-induced acute liver injury. Tim-3 is a negative regulator that is expressed by T cells and macrophages. Using antibodies against Tim-3 (anti-Tim-3 Ab), we studied the Tim-3 signal in an animal model of acute liver injury and found that a large number of inflammatory factors were upregulated. In vitro experimental data shown that anti-Tim-3 Ab treatment increased interferon-ɣ production by concanavalin A (ConA)-stimulated spleen T cells, and we found that the expression level of interleukin (IL)-6 was increased in a macrophage/spleen T cell coculture system, while administration of galectin-9 (Gal-9, a Tim-3 ligand) reduced the IL-6 production. This indicates the importance of the Tim-3/Gal-9 signalling pathway in maintaining hepatic homeostasis. The Tim-3 signalling pathway inhibits TLR4-mediated NF-κB activity, and an anti-Tim-3 Ab does not affect the liver injury in TLR4-deficient mice. Regulation between Tim-3 and TLR4 determines the severity of liver damage. The negative regulation of Tim-3 reflects the protective mechanisms of patients with impaired liver function, and these results provide important information about innate and adaptive responses in the regulation of liver damage. This finding is potentially important for the study of early liver injury.

Blockade of T-cell immunoglobulin and mucin domain-containing molecule 3 aggravates T-helper cell 1 polarization in immune thrombocytopenia

: An increased T-helper cell (Th) 1/Th2 ratio in the peripheral blood has been proposed to correlate with the disease activity of immune thrombocytopenia (ITP). T-cell immunoglobulin and mucin domain-containing molecule 3 (TIM-3) is a Th1-associated cell surface molecule that regulates Th1 responses and promotes tolerance. Consequently, we aimed to determine whether the regulation of TIM-3 expression is likely to be a promising therapeutic approach for ITP. In the present study, we investigated the immunomodulatory activities of TIM-3 in human peripheral blood mononuclear cell (PBMC) cultures. Levels of interferon-gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin (IL)-4, IL-5, IL-2, and IL-10 were determined in PBMCs from 11 ITP patients and 10 healthy patients after TIM-3 antibody administration for 48 h. The proliferation of PBMCs was examined by cell counting kit-8 assay. Flow cytometry was used to observe apoptosis by staining cells with annexin V-fluorescein isothiocyanate/propidine iodide. PBMCs from ITP patients secreted higher amounts of IFN-γ than those from control patients but paradoxically expressed lower levels of TIM-3. Depletion of TIM-3 in PBMCs in vitro using a TIM-3 antibody enhanced IFN-γ secretion, directly demonstrating that TIM-3 expression on human T cells regulates proliferation and IFN-γ secretion. Failure to upregulate the T-cell expression of TIM-3 may represent a novel intrinsic defect that contributes to the pathogenesis of ITP.

The Role of Co-stimulatory/Co-inhibitory Signals in Graft-vs.-Host Disease

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective immunotherapeutic approach for various hematologic and immunologic ailments. Despite the beneficial impact of allo-HCT, its adverse effects cause severe health concerns. After transplantation, recognition of host cells as foreign entities by donor T cells induces graft-vs.-host disease (GVHD). Activation, proliferation and trafficking of donor T cells to target organs and tissues are critical steps in the pathogenesis of GVHD. T cell activation is a synergistic process of T cell receptor (TCR) recognition of major histocompatibility complex (MHC)-anchored antigen and co-stimulatory/co-inhibitory signaling in the presence of cytokines. Most of the currently used therapeutic regimens for GVHD are based on inhibiting the allogeneic T cell response or T-cell depletion (TCD). However, the immunosuppressive drugs and TCD hamper the therapeutic potential of allo-HCT, resulting in attenuated graft-vs.-leukemia (GVL) effect as well as increased vulnerability to infection. In view of the drawback of overbroad immunosuppression, co-stimulatory, and co-inhibitory molecules are plausible targets for selective modulation of T cell activation and function that can improve the effectiveness of allo-HCT. Therefore, this review collates existing knowledge of T cell co-stimulation and co-inhibition with current research that may have the potential to provide novel approaches to cure GVHD without sacrificing the beneficial effects of allo-HCT.

Expression of Tim-3 in peripheral blood mononuclear cells and placental tissue in unexplained recurrent spontaneous abortion

The expression of T-cell immunoglobulin domain, mucin domain-3 (Tim-3) in unexplained recurrent spontaneous abortion (URSA) was investigated.Tim-3 mRNA expression in peripheral blood mononuclear cells (PBMCs) of URSA and control groups was assayed by fluorescent quantitative real-time polymerase chain reaction. Tim-3 protein expression intensity and localization in placental villi and uterine decidua were determined using immunohistochemical assay. The CD4Tim-3/CD4 cell ratio in PBMCs was determined by flow cytometry.Tim-3 mRNA expression in PBMCs was significantly higher in URSA than in normal controls (1.32 ± 0.25 vs 1.20 ± 0.12, P < .05). Tim-3 was expressed in placental tissue from both URSA patients and normal pregnant females (controls); however, the expression intensity was higher in the URSA group (0.54 ± 0.31 vs 0.35 ± 0.22, P < .05). CD4Tim-3/CD4 cell ratio in PBMCs was significantly higher in the URSA group than that in the control group (4.53 ± 1.66% vs 1.28 ± 0.71%, P < .05).Increased Tim-3 expression in PBMCs and placental tissue of URSA might affect maternal-fetal immune tolerance. Tim-3 was involved in the pathogenesis of URSA, which was expected to serve as an indicator for the immune evaluation of URSA.

TIM-3 Regulates CD103+ Dendritic Cell Function and Response to Chemotherapy in Breast Cancer

Intratumoral CD103⁺ dendritic cells (DCs) are necessary for anti-tumor immunity. Here we evaluated the expression of immune regulators by CD103⁺ DCs in a murine model of breast cancer and identified expression of TIM-3 as a target for therapy. Anti-TIM-3 antibody improved response to paclitaxel chemotherapy in models of triple-negative and luminal B disease, with no evidence of toxicity. Combined efficacy was CD8⁺ T cell dependent and associated with increased granzyme B expression; however, TIM-3 expression was predominantly localized to myeloid cells in both human and murine tumors. Gene expression analysis identified upregulation of Cxcl9 within intratumoral DCs during combination therapy, and therapeutic efficacy was ablated by CXCR3 blockade, Batf3 deficiency, or Irf8 deficiency.

Antitumor effect of membrane-type Tim-3 on hepatocellular carcinoma Hepa1-6 cells of ICR mice

In the present study, the inhibitory effect of transmembrane Tim-3 on hepatocellular carcinoma Hepa1-6 cells and the potential application of Tim-3 on immune system of Institute of Cancer Research (ICR) mice loaded with Hepa1-6 hepatocellular carcinoma was investigated. The animal model was established via inoculation of Hepa1-6 hepatocarcinoma cells at the hind thigh of ICR mice. Recombinant vector plasmids were transfected at the same site for gene therapy by injection to observe the inhibitory effect of Tim-3 on tumor growth. A panel of genes from tumor tissues at various time intervals was analyzed by reverse transcription-polymerase chain reaction. Flow cytometry was used to evaluate the proliferation and cytotoxicity of splenocytes after Tim-3 transfection. Synergistic effects of Tim-3 with tumor abnormal protein-1 (TAP1) was also studied. It was revealed that the growth of tumor was significantly suppressed after the transfection of Tim-3. In the presence of Tim-3, the proliferation of splenocytes and cytolysis in the early phase of tumor development was significantly enhanced, and this antitumor effect was further improved by the synergistic effect of Tim-3 with TAP1. Therefore, the membrane-type Tim-3 may behave as an effective immunoregulator to enhance antitumor immune responses. Furthermore the present findings suggest that antitumor immunity was improved by the combined effect of Tim-3 and TAP1.

T Cell-Derived CD70 Delivers an Immune Checkpoint Function in Inflammatory T Cell Responses

The CD27-CD70 pathway is known to provide a costimulatory signal, with CD70 expressed on APCs and CD27 functions on T cells. Although CD70 is also expressed on activated T cells, it remains unclear how T cell-derived CD70 affects T cell function. Therefore, we have assessed the role of T cell-derived CD70 using adoptive-transfer models, including autoimmune inflammatory bowel disease and allogeneic graft-versus-host disease. Surprisingly, compared with wild-type T cells, CD70^-/- T cells caused more severe inflammatory bowel disease and graft-versus-host disease and produced higher levels of inflammatory cytokines. Mechanistic analyses reveal that IFN-γ induces CD70 expression in T cells, and CD70 limits T cell expansion via a regulatory T cell-independent mechanism that involves caspase-dependent T cell apoptosis and upregulation of inhibitory immune checkpoint molecules. Notably, T cell-intrinsic CD70 signaling contributes, as least in part, to the inhibitory checkpoint function. Overall, our findings demonstrate for the first time, to our knowledge, that T cell-derived CD70 plays a novel immune checkpoint role in inhibiting inflammatory T cell responses. This study suggests that T cell-derived CD70 performs a critical negative feedback function to downregulate inflammatory T cell responses.

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.

Tim-3 and its role in regulating anti-tumor immunity

Immunotherapy is being increasingly recognized as a key therapeutic modality to treat cancer and represents one of the most exciting treatments for the disease. Fighting cancer with immunotherapy has revolutionized treatment for some patients and therapies targeting the immune checkpoint molecules such as CTLA-4 and PD-1 have achieved durable responses in melanoma, renal cancer, Hodgkin's diseases and lung cancer. However, the success rate of these treatments has been low and a large number of cancers, including colorectal cancer remain largely refractory to CTLA-4 and PD-1 blockade. This has provided impetus to identify other co-inhibitory receptors that could be exploited to enhance response rates of current immunotherapeutic agents and achieve responses to the cancers that are refectory to immunotherapy. Tim-3 is a co-inhibitory receptor that is expressed on IFN-g-producing T cells, FoxP3+ Treg cells and innate immune cells (macrophages and dendritic cells) where it has been shown to suppress their responses upon interaction with their ligand(s). Tim-3 has gained prominence as a potential candidate for cancer immunotherapy, where it has been shown that in vivo blockade of Tim-3 with other check-point inhibitors enhances anti-tumor immunity and suppresses tumor growth in several preclinical tumor models. This review discusses the recent findings on Tim-3, the role it plays in regulating immune responses in different cell types and the rationale for targeting Tim-3 for effective cancer immunotherapy.

The TIM Family of Cosignaling Receptors: Emerging Targets for the Regulation of Autoimmune Disease and Transplantation Tolerance

Currently, lifelong immune suppression regimens are required for solid organ and cellular transplantation and carry significant increased risk of infection, malignancy, and toxicity. For non-life-saving procedures such as islet transplantation, the risk/benefit ratio of lifelong immunosuppression versus benefit from transplantation requires even more careful balance. The search for specific agents to modulate the immune system without chronic immunosuppression is important for the broad application of islet transplantation. The T-cell immunoglobulin mucin (TIM) family is a distinct group of coreceptors that are differentially expressed on TH1 and TH2 cells, and have the potential to regulate both cytotoxic and humoral immune responses. Completed murine studies demonstrate Tim pathways may be important in the regulation of tolerance to self (auto), harmless (allergic), and transplant (allo) antigen; however, the potential impact of targeting Tim coreceptors has yet to be fully explored in transplantation tolerance induction or autoimmune disease. The current review examines the impact of Tim coreceptor targeting as an emerging therapeutic option for regulating autoimmune diseases and prevention of allograft rejection.

Tim-3, Lag-3, and TIGIT

Co-inhibitory receptors play a key role in regulating T cell responses and maintaining immune homeostasis. Their inhibitory function prevents autoimmune responses but also restricts the ability of T cells to mount effective immune responses against tumors or persistent pathogens. T cells express a module of co-inhibitory receptors, which display great diversity in expression, structure, and function. Here, we focus on the co-inhibitory receptors Tim-3, Lag-3, and TIGIT and how they regulate T cell function, maintenance of self-tolerance, their role in regulating ongoing T cell responses at peripheral tissues, and their synergistic effects in regulating autoimmunity and antitumor responses.

Clinical significance of serum soluble T-cell immunoglobulin and mucin domain 3 levels in systemic sclerosis: Association with disease severity

T-cell immunoglobulin and mucin domain 3 (TIM-3) has been thought to play a crucial role in the negative regulation of immune responses. Here, we examined the levels of serum soluble TIM-3 (sTIM-3) in patients with systemic sclerosis (SSc) and evaluated the results with respect to the clinical features of the disease. Patients with diffuse cutaneous SSc (dcSSc) had higher levels of sTIM-3 than those with limited cutaneous SSc and healthy individuals. Serum sTIM-3 levels were positively correlated with the severity of skin sclerosis in early phase dcSSc. Moreover, serum sTIM-3 levels were increased more often in patients with renal crisis and cardiac involvement than in those with normal sTIM-3 levels. These results suggest that serum sTIM-3 levels may be increased in patients with early phase dcSSc and associated with cardiac involvement and renal crisis. Measurement of serum sTIM-3 may be useful for risk stratification in the early stage of the disease.

[The role of Tim-3 mRNA in acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation]

OBJECTIVE

To investigate the role of Tim-3 gene expression in acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODS

Patients after allo-HSCT were retrospectively analyzed, this cohort of patients were divided into different groups according to disease states (grade 0-Ⅰ aGVHD group, grade Ⅱ-Ⅳ aGVHD group, improved aGVHD group) and time periods (+14-+30 d, +31-+60 d, +61-+100 d) to compare PBMC Tim-3 mRNA expression and plasma IFN-γ, IL-2 concentrations among them.

RESULTS

RT-PCR showed that in grade 0-Ⅰ aGVHD group, Tim-3 mRNA expression in patients +31-+60 d (7.24±2.79) was significantly higher than that in patients + 14-+ 30 d (4.60±1.66) and + 61-+ 100 d (3.86±1.36) (P<0.05). Tim-3 mRNA expressions of grade Ⅱ-Ⅳ aGVHD group in patients +14-+30 d, +31-+60 d, +61-+100 d were 9.54± 3.05, 10.14±3.28, 12.82±4.20, respectively, which in both +14-+30 d and +61-+100 d were significantly higher than that of grade 0-Ⅰ aGVHD and improved aGVHD groups (P<0.05). In patients +31-+60 d, Tim-3 expression of grade Ⅱ-Ⅳ aGVHD group was higher than improved aGVHD group (2.49±0.89), while no statistical difference when compared with grade 0-Ⅰ aGVHD group (7.24±2.79). In grade Ⅱ-Ⅳ aGVHD group, Tim-3 mRNA expression manifested no statistical difference among grades or organ involved (P>0.05). ELISA results showed that plasma IFN-γ and IL-2 concentrations were higher in grade Ⅱ-Ⅳ aGVHD group than of other groups, while no significant difference existed between grade 0-Ⅰ aGVHD and improved aGVHD groups (P<0.05).

CONCLUSION

Tim-3 played an important role in the process of aGVHD.

The Role of Biomarkers in the Diagnosis and Risk Stratification of Acute Graft-versus-Host Disease: A Systematic Review

Allogeneic hematopoietic cell transplantation (HCT) is an increasingly used curative modality for hematologic malignancies and other benign conditions. Attempts to reduce morbidity and mortality and improve survival in patients undergoing HCT are crucial. The ability to diagnose acute graft-versus-host disease (aGVHD) in a timely manner, or to even predict aGVHD before clinical manifestations, along with the accurate stratification of these patients, are critical steps to improve the treatment and outcomes of these patients. Many novel biomarkers that may help achieve these goals have been studied recently. This overview is intended to assist clinicians and investigators by providing a comprehensive review and analytical interpretation of the current knowledge concerning aGVHD and biomarkers likely to prove useful in diagnosis and risk stratification of this condition, along with the difficulties that hamper this approach.

Beyond CTLA-4 and PD-1, the Generation Z of Negative Checkpoint Regulators

In the last two years, clinical trials with blocking antibodies to the negative checkpoint regulators CTLA-4 and PD-1 have rekindled the hope for cancer immunotherapy. Multiple negative checkpoint regulators protect the host against autoimmune reactions but also restrict the ability of T cells to effectively attack tumors. Releasing these brakes has emerged as an exciting strategy for cancer treatment. Conversely, these pathways can be manipulated to achieve durable tolerance for treatment of autoimmune diseases and transplantation. In the future, treatment may involve combination therapy to target multiple cell types and stages of the adaptive immune responses. In this review, we describe the current knowledge on the recently discovered negative checkpoint regulators, future targets for immunotherapy.

Roles of the programmed cell death 1, T cell immunoglobulin mucin-3, and cluster of differentiation 288 pathways in the low reactivity of invariant natural killer T cells after chronic hepatitis B virus infection

One of the main responses of invariant natural killer T (iNKT) cells to antigen stimulation is the rapid production of interleukin (IL)-4 and interferon (IFN)-γ cytokines. There is a decline in the function of iNKT cells in chronic hepatitis B (CHB) patients. In this study, we explored the impact of programmed cell death 1 (PD-1), T cell immunoglobulin mucin-3 (Tim-3), and cluster of differentiation 28 (CD28) expression on iNKT cell functions in CHB patients. Flow cytometry was used to test iNKT frequencies and levels of PD-1, Tim-3, CD28, IL-4, and IFN-γ secreted by iNKT cells. An enzyme-linked immunosorbent assay (ELISA) was used to measure IL-4 and IFN-γ secretion upon α-galactosylceramide (α-GalCer) activation ex vivo. We found that the levels of expression of PD-1 and Tim-3 from iNKT cells in CHB patients were significantly higher than in healthy donors (p < 0.05), but there was lower expression of CD28 (p < 0.05) and an impaired capability to produce IL-4 and IFN-γ (p < 0.05). In vitro α-GalCer stimulation upregulated the expression of PD-1(+) iNKT cells (p < 0.05), Tim-3(+) iNKT cells (p < 0.05), and CD28(+) iNKT cells (p < 0.05). In response to combination therapies consisting of α-GalCer and anti-PDL1 monoclonal antibody (mAb) and/or anti-Tim-3 mAbs and/or anti-CD80/anti-CD28 mAbs, IL-4(+) and IFN-γ(+) iNKT cells demonstrated different degrees of growth (p < 0.05). The functional decline of iNKT cells was closely related to the decrease in CD28 expression and the increases of Tim-3 and PD-1. In addition, clinical antiviral treatment with lamivudine could partially restore the immune function of iNKT cells in CHB patients.

The Clinical Significance of Abnormal Tim-3 Expression on NK Cells from Patients with Gastric Cancer

AIM

To investigate the clinical significance of Tim-3 (T-cell immunoglobulin- and mucin-domain-containing molecule 3) expression in natural killer (NK) cells from patients with gastric cancer.

MATERIALS AND METHODS

Sixty-two patients with gastric cancer and 32 healthy controls were recruited for this study. Tim-3 expression in peripheral blood samples was analyzed using flow cytometry. The expression pattern of Tim-3 on NK cells was also confirmed using a gastric cancer-bearing mouse model. To further investigate the mechanisms that regulate Tim-3 expression, T-bet(-/-), Eomes(-/-), and Eomes/T-bet double knockout mice were utilized. Additionally, we statistically analyzed the clinical significance of Tim-3 expression on NK cells.

RESULTS

We found that the levels of Tim-3 in NK cells obtained from patients with gastric cancer were significantly higher than the levels in healthy controls. Clinical analyses showed that Tim-3 levels on NK cells were associated with advanced tumor stage. In a tumor-bearing mouse model, Tim-3 levels in NK cells increased with tumor growth, indicating that tumor progression could induce Tim-3 expression in NK cells. Finally, we report that T-bet is a key factor involved in regulating Tim-3 expression.

CONCLUSION

Our data indicate that Tim-3 expression on NK cells is regulated by T-bet, and that Tim-3 levels correlate with advanced stages of gastric cancer.

Tim-3 induces Th2-biased immunity and alternative macrophage activation during Schistosoma japonicum infection

T cell immunoglobulin- and mucin-domain-containing molecule 3 (Tim-3) has been regarded as an important regulatory factor in both adaptive and innate immunity. Recently, Tim-3 was reported to be involved in Th2-biased immune responses in mice infected with Schistosoma japonicum, but the exact mechanism behind the involvement of Tim-3 remains unknown. The present study aims to understand the role of Tim-3 in the immune response against S. japonicum infection. Tim-3 expression was determined by flow cytometry, and increased Tim-3 expression was observed on CD4(+) and CD8(+) T cells, NK1.1(+) cells, and CD11b(+) cells from the livers of S. japonicum-infected mice. However, the increased level of Tim-3 was lower in the spleen than in the liver, and no increase in Tim-3 expression was observed on splenic CD8(+) T cells or CD11b(+) cells. The schistosome-induced upregulation of Tim-3 on natural killer (NK) cells was accompanied by reduced NK cell numbers in vitro and in vivo. Tim-3 antibody blockade led to upregulation of inducible nitric oxide synthase and interleukin-12 (IL-12) mRNA in CD11b(+) cells cocultured with soluble egg antigen and downregulation of Arg1 and IL-10, which are markers of M2 macrophages. In summary, we observed schistosome-induced expression of Tim-3 on critical immune cell populations, which may be involved in the Th2-biased immune response and alternative activation of macrophages during infection.

The Tim-3/galectin-9 pathway involves in the homeostasis of hepatic Tregs in a mouse model of concanavalin A-induced hepatitis

T cell immunoglobulin- and mucin-domain-containing molecule-3 (Tim-3) is a negative regulator of interferon (IFN)-γ-secreting CD4(+) Th1 cells and plays a key role in autoimmune diseases. Here, we report that galectin-9 expression was increased in hepatic CD4(+)CD25(+) T cells in a mouse model of concanavalin A (Con A)-induced hepatitis. Moreover, Tim-3 showed increased levels in CD4(+)CD25(+) Foxp3(+) regulatory T cells (Tregs). Further analyses showed that blocking the Tim-3/galectin-9 pathway resulted in the suppression of Tregs in vitro, thereby significantly increasing interferon (IFN)-γ production from hepatic Teffs. Moreover, blockade of Tim-3 in vivo with an anti-Tim-3 antibody exacerbated the acute hepatitis, possibly by increased IFN-γ production. Furthermore, we found that in vitro activation of CD4(+)CD25(-) T cells with the T cell receptor (TCR) plus interleukin 2 (IL-2) up-regulated Tim-3 expression. And the induced Tim-3 interacted with galectin-9 to induce CD4(+) T cell apoptosis which could be partly reversed by blocking Tim-3 signaling. Our results suggested that the Tim-3/galectin-9 pathway plays a critical role in the homeostasis of hepatic Tregs through the elimination induction in Teffs and the inhibition of IFN-γ release, which contributes to the pathogenesis of liver damage and constitutes at least part of the mechanism underlying the induction of hepatitis by Con A.

Galectin-9 in combination with rapamycin induces cardiac allograft tolerance in mice

BACKGROUND

Galectin-9 serves opposing roles in the innate and adaptive immune systems. Galectin-9 triggers T-cell immunoglobulin mucin-3 (Tim-3) on T helper type 1 (Th1) cells, thereby terminating Th1 immunity and protecting allografts from host immune attacks. Meanwhile, galectin-9 promotes the maturation of dendritic cells (DCs) that deliver proinflammatory signals. We previously showed that galectin-9 significantly prolongs cardiac allograft survival in mice but failed to induce tolerance. This study aimed at improving the administration protocol to induce allograft tolerance. We examined whether rapamycin can reverse the proinflammatory effects of galectin-9 on DCs and whether rapamycin synergizes with galectin-9 to induce cardiac allograft tolerance.

METHODS

Monocytes/DCs from cardiac allografts were assessed for Tim-3 expression by flow cytometry. Costimulatory molecules CD80/CD86 were measured on galectin-9/rapamycin-treated bone marrow-derived DCs by flow cytometry. We performed heterotopic cervical cardiac transplantation using BALB/c donors and C57BL/6 recipients and assessed graft survival time. T cells of long-term surviving recipients were immunoassayed for interferon-γ and interleukin-4 secretion.

RESULTS

Allograft-infiltrating monocytes/DCs expressed high Tim-3 levels (47.3%±5.6%). Expression of CD80/CD86 was up-regulated on galectin-9-treated bone marrow-derived DCs, which was reversed by rapamycin. Combined treatment with galectin-9 and rapamycin promoted the permanent acceptance of fully mismatched grafts (survival time >180 days; n=6). However, treatment with galectin-9 or rapamycin alone was not sufficient to induce tolerance. Galectin-9/rapamycin-induced tolerance was associated with low donor-specific interferon-γ and interleukin-4 secretion.

CONCLUSIONS

Rapamycin inhibits proinflammatory effects of galectin-9 on DCs. Combined treatment of galectin-9 and rapamycin promotes allografts tolerance, which is associated with reduced Th1 and Th2 responses.