Tim-3+ T-bet+ tumor-specific Th1 cells colocalize with and inhibit development and growth of murine neoplasms

CTLA-4 antibody ipilimumab negatively affects CD4+ T-cell responses in vitro

Immune checkpoint inhibitors targeting coinhibitory pathways in T cells possess efficacy in combating cancer. In addition to PD-1/PD-L1 and CTLA-4 antibodies which are already established in tumor immunotherapy, immune checkpoints such as LAG-3 or BTLA are emerging, which may have the potential to enhance T-cell responses alone or in combination with PD-1 blockers. CD4⁺ T cells play a central role in the immune system and contribute to productive immune responses in multiple ways. The effects of immune checkpoint inhibitors on this cell subset may thus critically influence therapeutic outcomes. Here, we have used in vitro responses to tetanus toxoid (TT) as a model system to study the effects of immune checkpoint inhibitors on CD4⁺ T-cell responses. CFSE-labeled PBMCs of 65 donors were stimulated with TT in the presence of blocking antibodies to PD-L1, CTLA-4, LAG-3, or BTLA for 7 days. We found that the PD-L1 antibody greatly enhanced cytokine production and antigen-specific CD4⁺ T-cell proliferation, whereas blocking antibodies to BTLA or LAG-3 did not augment responses to TT. Surprisingly, the presence of the therapeutic CTLA-4 antibody ipilimumab resulted in a significant reduction of CD4⁺ T-cell proliferation and cytokine production. Stimulation experiments with an IgG4 variant of ipilimumab indicated that the inhibitory effect of ipilimumab was dependent on its IgG1 isotype. Our results indicate that the therapeutic CTLA-4 antibody ipilimumab can impair CD4⁺ effector T-cell responses and that this activity is mediated by its Fc part and CD16-expressing cells.

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.

T-cell immunoglobulin mucin-3 expression in invasive ductal breast carcinoma: Clinicopathological correlations and association with tumor infiltration by cytotoxic lymphocytes

As a negative regulatory molecule, T-cell immunoglobulin and mucin domain-3 (Tim-3) is closely associated with tumor immunological tolerance. The aim of this study was to investigate Tim-3 expression in invasive ductal breast cancer (IDC), its effect on clinicopathological parameters and its association with cytotoxic lymphocyte infiltration. Tim-3 protein expression was measured in 150 paraffin-embedded IDC specimens and 100 paired normal breast tissue specimens by immunohistochemistry. It was demonstrated that the infiltration of the tumor by CD8⁺ T cells was significantly higher compared with that of normal tissue, and the Tim-3 expression on CD8⁺ T cells was higher in IDC tissue compared with that in normal tissue; the differences were statistically significant (both P-values=0.000). The median expression level of Tim-3 on tumor cells was significantly associated with clinicopathological parameters such as age, axillary lymph node metastasis and TNM stage (P=0.015, 0.001 and 0.027, respectively). The expression of Tim-3 on CD8⁺ T cells was correlated with lymph node metastasis, World Health Organization (WHO) grade and molecular classification (P=0.000, 0.004 and 0.000, respectively). Additionally, the number of tumor-infiltrating CD8⁺ T cells was associated with primary tumor size, lymph node metastasis, WHO grade, Ki-67 and molecular classification (P=0.017, 0.002, 0.007, 0.003 and 0.000, respectively). Thus, Tim-3 may promote the development and progression of breast cancer and affect the tumor microenvironment; thus, it may be used as an independent prognostic factor for IDC patients.

Role of TIM-3 in ovarian cancer

Evidences have suggested that immunotherapy for ovarian cancer is effective. Immune checkpoints have emerged in the field of cancer immunotherapy. Multiple studies have shown negative regulation of TIM-3 expression on CD4⁺ and CD8⁺ T cells and other immunocytes. Overexpression of TIM-3 in innate immune cells has been found in certain types of tumor. The blockade of TIM-3 leads to sustained anti-tumor reactions. TIM-3 plays an inhibitive role for immunity in ovarian cancer. TIM-3 is involved in the development of various subtypes of ovarian cancer and thus has the potential to be a therapeutic target for treatment of ovarian cancer.

Downregulation of T cell immunoglobulin and mucin protein 3 in the pathogenesis of intracranial aneurysm

Evidence has shown that inflammation acts as a critical contributor to the pathogenesis of intracranial aneurysm (IA), a potentially devastating clinical problem. T cell immunoglobulin and mucin protein 3 (Tim-3) is a negative regulatory molecule and plays important roles in the inflammation process. In the current study, we investigated the expression of Tim-3 and its correlation with tumor necrosis factor alpha (TNF-α) in IA patients. Data showed that both messenger RNA (mRNA) level and protein level of Tim-3 were significantly decreased in CD4+ T cells and CD8+ T cells from IA patients than from healthy controls (P < 0.001). However, expression of Tim-3 was not altered in monocytes between patients and healthy donors. Further analyses revealed that patients with ruptured aneurysm had significantly lower level of Tim-3 in CD8+ T cells than those with un-ruptured aneurysm. In addition, a negative correlation between serum level of TNF-α and the expression of Tim-3 in CD4+ T cells was observed in IA patients. Similar correlation was also identified in CD8+ T cells from IA patients. Our study suggests that Tim-3 may participate in the development and progression of IA by probably its negative regulation on TNF-α.

Emerging immune checkpoints for cancer therapy

BACKGROUND

Immunotherapy with immune checkpoint inhibitors has emerged as promising treatment modality for cancer based on the success of anti-CTLA-4 and -PD-1/PD-L1 antibodies. LAG-3 and TIM-3 are two new immune checkpoints. The aim of this work is to review the role and application of LAG-3 and TIM-3 for cancer immunotherapy.

MATERIAL AND METHODS

Literatures were searched and collected in Medline/PubMed.

RESULTS

LAG-3 is presented as a CD4 homolog type I transmembrane protein which binds MHC class II molecules. LAG-3 negatively regulates T cell proliferation, homeostasis and function. IMP321 is formed of an extracellular portion of human LAG-3 fused to the Fc fraction of human IgG1 and has shown increased T cell responses and tolerability in phase I studies on advanced renal cell cancer. When combined with paclitaxel, IMP321 has exerted immune enhancement and tumor inhibition with no significant IMP321-related adverse events. TIM-3 belongs to the TIM family and mainly negatively regulates Th1 immunity. The TIM-3/galectin-9 pathway contributes to the suppressive tumor microenvironment. TIM-3 overexpression is associated with poor prognosis in a variety of cancers. Both LAG-3 and TIM-3 are coexpressed with other immune checkpoints. The application of LAG-3 or TIM-3 does play an important role in anti-tumor responses, and maybe better when combing with anti-CTLA-4 and anti-PD-1/L1 antibodies.

CONCLUSIONS

These two immune checkpoints play crucial roles in cancer development and may be used in future clinical practice of cancer therapy.

T-cell immunoglobulin- and mucin-domain-containing molecule 3 genetic variants and HIV+ non-Hodgkin lymphomas

T cell immunoglobulin- and mucin-domain-containing molecule 3 (TIM-3) has been established as a negative regulatory molecule and plays a critical role in inflammatory diseases such as rheumatoid arthritis, hepatitis B and C, and human immunodeficiency virus (HIV)-related inflammation. Recent studies have shown that chronic inflammation may greatly affect the pathogenesis of non-Hodgkin lymphomas (NHL). The aim of this study was to investigate whether polymorphisms in the TIM-3 gene were associated with susceptibility to non-NHL and HIV-related NHL. Three polymorphisms in TIM-3 gene (-1516G/T, -574G/T, and +4259T/G) were identified by polymerase chain reaction-restriction fragment length polymorphism in 434 NHL patients, 62 HIV-related NHL cases, and 512 healthy controls. Results showed that the prevalence of -574GT genotype and +4259TG genotype were significantly increased in the NHL cases than in controls (odds ratio (OR) = 2.72, 95% confidence interval (CI) = 1.50-4.92, p = 0.0006 and OR = 2.59, 95% CI = 1.49-4.49, p = 0.0005, respectively). The -1516G/T polymorphism did not reveal significant difference between patients and healthy controls. When analyzing the TIM-3 polymorphisms in HIV-related NHL patients, data showed that HIV+ NHL patients had higher prevalence of -574GT or +4259TG genotypes than those cases without HIV infection (OR = 3.48, 95% CI = 1.67-7.28, p = 0.0005 and OR = 2.92, 95% CI = 1.42-6.01, p = 0.0026, respectively). These results suggested polymorphisms in TIM-3 gene could be new risk factors for NHL as well as HIV-related NHL and suggested a possible role of the inflammatory factor in these diseases.

Tim-3 expression defines regulatory T cells in human tumors

Tim-3, a member of the novel Tim (T cell immunoglobulin and mucin domain) family, has been reported to negatively regulate the immune responses against viral infection and had implications for autoimmune disease. However, the nature and role of Tim-3⁺ CD4 T cells in human tumors remain largely unknown. In the present study, we characterized Tim-3⁺ CD4 T cells in 100 specimens from human hepatocellular, cervical, colorectal and ovarian carcinoma patients. Compared with peripheral blood and nontumor-infiltrating lymphocytes, the lymphocytes isolated from the corresponding tumor tissues of hepatocellular, cervical, colorectal and ovarian carcinoma patients contained significantly greater proportion of Tim-3⁺ CD4 T cells. The majority of tumor-derived Tim-3⁺ CD4 T cells exhibited an impaired capacity to produce IFN-γ and IL-2, but expressed higher levels of CD25, Foxp3, CTLA-4 and GITR than their Tim-3⁻ CD4 T cell counterparts. In contrast, most Tim-3⁺ CD4 T cells isolated from the paired nontumor tissues and peripheral blood did not express these molecules. Moreover, tumor-derived Tim-3⁺ CD4 T cells, but not tumor-derived Tim-3⁻ CD4 T cells, significantly suppressed the proliferation of autologous CD8⁺ T cells in vitro. Notably, multi-color immunofluorescence and confocal microscopy demonstrated that Tim-3⁺Foxp3⁺CD4⁺ cells were preferentially distributed in the tumor nest rather than the peritumoral stroma of hepatocellular carcinoma. Together, our data indicate that Tim-3-expressing CD4 T cells in human tumors could represent the functional regulatory T cells which contribute to the formation of the immune-suppressive tumor micromilieu.

Epigenetic regulation of beta2-adrenergic receptor expression in T(H)1 and T(H)2 cells

We showed previously that murine naive CD4(+) T cells and T(H)1 cell clones express the beta2-adrenergic receptor (β(2)AR), while T(H)2 cell clones do not. We report here that naive CD4(+) T cells that differentiated for 1-5 days under T(H)1 driving conditions increased β(2)AR gene expression, while cells cultured under T(H)2 driving conditions decrease β(2)AR gene expression. Chromatin immunoprecipitation revealed that the increase in β(2)AR gene expression in T(H)1 cells is mediated by an increase in histone 3 (H3) and H4 acetylation, as well as an increase in histone 3 lysine 4 (H3K4) methylation. Conversely, the decrease in β(2)AR gene expression in T(H)2 cells is mediated by a decrease in H3 and H4 acetylation and a decrease in H3K4 methylation, as well as an increase H3K9 and H3K27 methylation. The histone changes could be detected as early as 3 days of differentiating conditions. Genomic bisulfite sequencing showed that the level of methylated CpG dinucleotides within the promoter of the β(2)AR gene was increased in T(H)2 cells as compared to naive and T(H)1 cells. Collectively, these results suggest that epigenetic mechanisms mediate maintenance and repression, respectively, of the β(2)AR gene expression in T(H)1- and T(H)2-driven cells, providing a potential mechanism by which the level of β(2)AR expression might be modulated pharmacologically within immune cells and other cell types in which the expression profile may change during a disease process.

In vivo tumor suppression activity by T cell-specific T-bet restoration

T-box-containing protein expressed in T cells (T-bet) is a master transcription factor for the development of interferon (IFN) gamma-producing T helper 1 (Th1) cells and also functions in other immune cells including natural killer (NK), cytotoxic T lymphocytes and dendritic cells. T-bet-deficient mice increased susceptibility to viral infection and tumor development due to the defective functions of immune cells. T-bet is known to play a key role in NK-mediated antimetastatic response; however, it remains to be characterized whether T-bet is essential for in vivo tumor suppression mediated by T cells. Here, we have investigated in vivo tumor suppression effect of T-bet-restored T cells using T cell-specific and inducible T-bet transgenic mice generated in a T-bet-deficient background. T-bet-null mice increased susceptibility to tumor development, whereas induction of T cell-specific T-bet expression upon melanoma cell injection substantially suppressed tumor development by inducing IFNgamma production in T cells and tumor cell apoptosis. Late induction of T-bet expression in tumor-bearing mice produced comparable amounts of IFNgamma with control and significantly decreased tumor volume. In addition, increased melanoma lung metastasis in T-bet-deficient mice was strikingly inhibited by T-bet restoration in T cells. Intravenous injection of activated Th1 cells, not T-bet-null Th1 cells, attenuated metastatic melanoma progression, in addition, restoration of T-bet in T-bet-null Th1 cells certainly retrieved antimetastatic activity. These results suggest that T-bet expression in T cells is crucial for the control of tumor development and antimetastatic activity.

T cell Ig and mucin domain proteins and immunity

Proteins of the transmembrane (or T cell) Ig and mucin domain (TIM) family are expressed by multiple cell types within the immune systems of rodents and humans. Studies over the last several years have suggested that these proteins may be promising targets for therapeutic manipulation of immune responses. This review discusses the progress that has been made in understanding TIM protein function in the immune system, as well as some of the unresolved issues that remain on the road to eventually targeting TIM proteins for enhancing or inhibiting immunity.

Pilot study of sentinel-node-based adoptive immunotherapy in advanced colorectal cancer

Background

Despite optimal surgical treatment and modern adjuvant therapies, 50% of patients diagnosed with colorectal cancer die within 5 years. Immunotherapy offers an appealing complement to traditional chemotherapy, with possible long-term protection against tumor recurrences through immunological memory. We have conducted a pilot study of a novel adoptive immunotherapy, using autologous, in vitro expanded lymphocytes isolated from the tumor-draining sentinel lymph node.

Study Design

Sentinel nodes were recovered from 16 patients with disseminated or locally advanced, high-risk colorectal cancer. Single-cell suspensions of sentinel-node-acquired lymphocytes were clonally expanded in vitro in the presence of autologous tumor extract and returned as a transfusion. Patients were followed with clinical and radiological evaluations. Long-term survival was compared with traditionally treated controls.

Results

Sentinel-node-acquired CD4⁺ Th1-lymphocytes could be clonally expanded in vitro and safely administered to all 16 patients without side-effects. In four out of nine stage IV patients, complete tumor regression occurred. Median survival time in the stage IV patients (n = 9) was 2.6 years, as compared with 0.8 years in conventionally treated controls. A dose-dependent effect with regards to reduced tumor burden and long-term survival was observed.

Conclusion

Sentinel-node-based adoptive immunotherapy is feasible; the method has shown no apparent side-effects and appears to convey therapeutic antitumor effects. Further studies are justified to determine its efficacy and precise role in the treatment of colorectal cancer.

Expression of Tim-3 Is Transiently Increased before Development of Anterior Chamber-Associated Immune Deviation

PURPOSE

To assess the expression of T-cell immunoglobulin- and mucin-domain-containing molecule 3 (Tim-3) in the spleens of BALB/c mice undergoing anterior chamber-associated immune deviation (ACAID).

METHODS

ACAID was generated after intracameral (i.c.) injection of ovalbumin (OVA) into BALB/c mice and evaluated by assessing the delayed-type hypersensitivity (DTH) response following a subsequent subcutaneous (s.c.) injection of OVA emulsified in complete Freund's adjuvant (CFA) on Days 0, 3, 7, 14, 21 and 28. Tim-3 mRNA levels were detected using real-time RT-PCR, and the frequency of CD4+Tim-3+ T cells in splenocytes as well as the coexpression of Tim-3 with CD25 on CD4+ T cells were assessed by flow cytometry.

RESULTS

A significantly suppressed DTH response was observed on Days 7, 14, 21, and 28, but not on Days 0 and 3 during the development of ACAID. The levels of Tim-3 mRNA and the frequency of CD4+CD25+Tim-3+ T cells in the splenocytes reached a peak on Day 3, declined on Day 7, and returned to basal levels thereafter.

CONCLUSIONS

A transient upregulation of Tim-3 expression was observed in the early stage of ACAID, suggesting its possible involvement in the development of ACAID.

Antitumor activity of a self-adjuvanting glyco-lipopeptide vaccine bearing B cell, CD4+ and CD8+ T cell epitopes

Molecularly defined synthetic vaccines capable of inducing both antibodies and cellular anti-tumor immune responses, in a manner compatible with human delivery, are limited. Few molecules achieve this target without utilizing external immuno-adjuvants. In this study, we explored a self-adjuvanting glyco-lipopeptide (GLP) as a platform for cancer vaccines using as a model MO5, an OVA-expressing mouse B16 melanoma. A prototype B and T cell epitope-based GLP molecule was constructed by synthesizing a chimeric peptide made of a CD8(+) T cell epitope, from ovalbumin (OVA(257-264)) and an universal CD4(+) T helper (Th) epitope (PADRE). The resulting CTL-Th peptide backbones was coupled to a carbohydrate B cell epitope based on a regioselectively addressable functionalized templates (RAFT), made of four alpha-GalNAc molecules at C-terminal. The N terminus of the resulting glycopeptides (GP) was then linked to a palmitic acid moiety (PAM), obviating the need for potentially toxic external immuno-adjuvants. The final prototype OVA-GLP molecule, delivered in adjuvant-free PBS, in mice induced: (1) robust RAFT-specific IgG/IgM that recognized tumor cell lines; (2) local and systemic OVA(257-264)-specific IFN-gamma producing CD8(+) T cells; (3) PADRE-specific CD4(+) T cells; (4) OVA-GLP vaccination elicited a reduction of tumor size in mice inoculated with syngeneic murine MO5 carcinoma cells and a protection from lethal carcinoma cell challenge; (5) finally, OVA-GLP immunization significantly inhibited the growth of pre-established MO5 tumors. Our results suggest self-adjuvanting glyco-lipopeptide molecules as a platform for B Cell, CD4(+), and CD8(+) T cell epitopes-based immunotherapeutic cancer vaccines.

Tumor-specific CD4+ T cells render the tumor environment permissive for infiltration by low-avidity CD8+ T cells

CD4+ T cells enhance tumor destruction by CD8+ T cells. One benefit that underlies CD4+ T cell help is enhanced clonal expansion of newly activated CD8+ cells. In addition, tumor-specific CD4+ help is also associated with the accumulation of greater numbers of CD8+ T cells within the tumor. Whether this too is attributable to the effects of help delivered to the CD8+ cells during priming within secondary lymphoid tissues, or alternatively is due to the action of CD4+ cells within the tumor environment has not been examined. In this study, we have evaluated separately the benefits of CD4+ T cell help accrued during priming of tumor-specific CD8+ T cells with a vaccine, as opposed to the benefits delivered by the presence of cognate CD4+ cells within the tumor. The presence of CD4+ T cell help during priming increased clonal expansion of tumor-specific CD8+ T cells in secondary lymphoid tissue; however, CD8+ T cells that have low avidity for tumor Ag were inefficient in tumor invasion. CD4+ T cells that recognized tumor Ag were required to facilitate accumulation of CD8+ T cells within the tumor and enhance tumor lysis during the acute phase of the response. These experiments highlight the ability of tumor-specific CD4+ T cells to render the tumor microenvironment receptive for CD8+ T cell immunotherapy, by facilitating the accumulation of all activated CD8+ T cells, including low-avidity tumor-specific and noncognate cells.

Tumor-specific Th17-polarized cells eradicate large established melanoma

CD4+ T cells can differentiate into multiple effector subsets, but the potential roles of these subsets in anti-tumor immunity have not been fully explored. Seeking to study the impact of CD4+ T cell polarization on tumor rejection in a model mimicking human disease, we generated a new MHC class II-restricted, T-cell receptor (TCR) transgenic mouse model in which CD4+ T cells recognize a novel epitope in tyrosinase-related protein 1 (TRP-1), an antigen expressed by normal melanocytes and B16 murine melanoma. Cells could be robustly polarized into Th0, Th1, and Th17 subtypes in vitro, as evidenced by cytokine, chemokine, and adhesion molecule profiles and by surface markers, suggesting the potential for differential effector function in vivo. Contrary to the current view that Th1 cells are most important in tumor rejection, we found that Th17-polarized cells better mediated destruction of advanced B16 melanoma. Their therapeutic effect was critically dependent on interferon-gamma (IFN-gamma) production, whereas depletion of interleukin (IL)-17A and IL-23 had little impact. Taken together, these data indicate that the appropriate in vitro polarization of effector CD4+ T cells is decisive for successful tumor eradication. This principle should be considered in designing clinical trials involving adoptive transfer-based immunotherapy of human malignancies.

Cytokine levels during pregnancy influence immunological profiles and neurobehavioral patterns of the offspring

The underlying causes of autism spectrum disorders (ASD) are unknown, but clinical and experimental studies indicate immune mechanisms, in general, and cytokine dysregulation, in particular, as contributing factors in their etiology. We developed a prenatal mouse model of autism to demonstrate that circulating levels of defined cytokines in pregnant dams could influence fetal development and behavioral characteristics in their offspring. We administered daily injections of murine IL-2 (0.4 mug in phosphate-buffered saline [PBS]) to pregnant mice during mid-gestation, and analyzed their offspring (IL-2 pups) in comparison to offspring of pregnant mice injected with vehicle only (PBS pups). Significant levels of IL-2 were present in amniotic fluid and tissues from embryos of dams given radiolabeled IL-2, indicating that the injected IL-2 crossed the placenta and entered the fetuses. Lymphocytes from IL-2 pups demonstrated accelerated T cell development, with a skewing toward TH1 cell differentiation. IL-2 pups also showed in vitro proliferative and cytotoxicity responses that were significantly higher than control PBS pups when stimulated with syngeneic B lymphoma cells or allogeneic spleen cells. In addition to their previously shown increases in open-field activity, grooming and rearing behavior, offspring of IL-2-injected (vs. PBS-injected) dams also displayed abnormal new motor learning as assessed through acquisition of the classically conditioned eyeblink response. These results suggest that increases in maternal levels of IL-2 during pregnancy induce in their offspring long-lasting increased vulnerability to neurobehavioral abnormalities associated with autism, and provide a valid animal model to determine the underlying immunological mechanisms.

TIM-3 as a therapeutic target in human inflammatory diseases

T-cell immunoglobulin- and mucin-domain-containing molecule-3 (Tim-3) was the first, and is presently the only, surface molecule that can specifically identify T(H)1 cells in both mice and humans. Engagement of Tim-3 by its ligand galectin-9 negatively regulates IFN-gamma secretion and influences the ability to induce T cell tolerance in both mice and man. Numerous studies have demonstrated that Tim-3 influences autoimmune diseases, including diabetes and multiple sclerosis, and its role in other inflammatory diseases including allergies and cancer is beginning to become clear.

CpG oligodeoxynucleotide-induced immunity prevents growth of germinal center-derived B lymphoma cells

Therapeutic efficacy of CpG oligodeoxynucleotide (ODN) ISS 1018 was tested in a murine B cell lymphoma model. Previous studies showed that the B lymphoma cells of SJL mice stimulate vigorous proliferation of host CD4(+) TH cells that is unaccompanied by development of tumor-specific CTL. In the presence of ISS 1018, however, tumor cells stimulated high levels of CTL activity in vitro, and this cytotoxic activity was inhibited when anti-IL-12 mAb was added to the cultures. Tumor cells pre-incubated with ISS 1018 were also able to generate CTL without addition of exogenous ODN, and FACS analysis revealed that following incubation with ISS 1018 for 24 h, tumor cells exhibited upregulation of MHC I, MHC II, and co-stimulatory molecule CD80. Finally, tumor-injected mice treated with ISS 1018 showed significantly less growth of tumor cells in lymph nodes and spleen, and exhibited prolonged survival compared to mice treated with a control ODN. The documented effects of CpG ODNs to stimulate cytokines, such as IL-12, from antigen presenting cells, and to upregulate expression of MHC Class I and Class II, as well as co-stimulatory molecules on tumor cells, are also the likely mechanisms by which CTL are generated by ISS 1018 in the SJL B cell lymphoma model.

Soluble Form of T Cell Ig Mucin 3 Is an Inhibitory Molecule in T Cell-Mediated Immune Response

T cell Ig mucin 3 (Tim-3) has been found to play an important role in Th1-mediated auto- and alloimmune responses, but the function of soluble form of Tim-3 (sTim-3) remains to be elucidated. In this study, we report the inhibitory effect of sTim-3 on T cell-mediated immune response. In this study, sTim-3 mRNA was found, among different tissues and organs, only in splenic cells, and the activation of splenocytes resulted in up-regulated production of both sTim-3 mRNA and protein. We constructed a eukaryotic expression plasmid, psTim-3, which expresses functional murine sTim-3. In C57BL/6 mice inoculated with B16F1 melanoma cells, the growth of tumor was facilitated by the expression of this plasmid in vivo. Furthermore, sTim-3 inhibited the responses of T cells to Ag-specific stimulation or anti-CD3 mAb plus anti-CD28 mAb costimulation and the production of cytokines IL-2 and IFN-gamma in vitro. In tumor rejection model, sTim-3 significantly impaired T cell antitumor immunity, evidenced by decreased antitumor CTL activity and reduced amount of tumor-infiltrating lymphocytes in tumor. Real-time PCR analysis of gene expression in tumor microenvironment revealed the decreased expression of Th1 cytokine genes and the unchanged profile of the genes related to T regulatory cell function, suggesting that the inhibitory effect of sTim-3 on the generation of Ag-specific T cells in vivo is dominated by T effector cells rather than T regulatory cells. Our studies thus define sTim-3 as an immunoregulatory molecule that may be involved in the negative regulation of T cell-mediated immune response.

The TIM gene family regulates autoimmune and allergic diseases

The recently identified TIM gene family encodes cell-surface receptors that are involved in the regulation of Th1- and Th2-cell-mediated immunity. Tim-3 protein is specifically expressed on Th1 cells and negatively regulates Th1 responses, whereas Tim-2 is preferentially expressed in Th2 cells. Tim-1, previously identified as the hepatitis A virus receptor, co-stimulates T-cell expansion and cytokine production. Tim-4, which is preferentially expressed on mature dendritic cells, is the ligand for Tim-1. In mouse models of asthma and multiple sclerosis, affecting the function of Tim molecules altered disease phenotype. Because TIM molecules are differentially expressed on effector Th1 and Th2 cells, further understanding of the mechanisms by which they regulate Th1- and Th2-effector functions will probably provide opportunities for the therapeutic modulation of immune-mediated diseases.