Anti-T-cell Ig and mucin domain-containing protein 1 antibody decreases TH2 airway inflammation in a mouse model of asthma

Tim-1 Deficiency Aggravates High-Fat Diet-Induced Steatohepatitis in Mice

Non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) is commonly associated with obesity and characterized by excessive lipid accumulation and liver inflammation. The T cell immunoglobulin and mucin domain 1 (Tim-1), also known as hepatitis A virus cellular receptor 1 (Havcr-1) and kidney injury molecule 1 (Kim-1), has been shown to affect innate immunity-driven proinflammatory cascade in liver ischemia-reperfusion injury. However, its contribution to obesity-related NAFLD/NASH remains unknown. Thus, this study was designed to evaluate the role of Tim-1 in obesity-related liver inflammation and injury in wild-type (WT) and Tim-1-deficient (Tim-1^-/-) C57BL/6J mice fed a high-fat diet (HFD) for 5-6 months. HFD feeding induced steatosis and upregulated Tim-1 gene expression in the liver of WT mice. Surprisingly, Tim-1^-/- mice on HFD diet exhibited an exacerbation of hepatic steatosis, accompanied with an elevation of protein levels of fatty acid translocase CD36 and sterol regulatory element binding protein 1 (SREBP1). Tim-1 deficiency also enhanced HFD-induced liver inflammation and injury, as evidenced by augmented increase in hepatic expression of pro-inflammatory factor lipocalin 2 and elevated serum alanine transaminase (ALT). In addition, gene expression of type I, III and IV collagens and liver fibrosis were greatly enhanced in HFD Tim-1^-/- mice compared with HFD WT mice. HFD-induced hepatic expression of YM-1, a specific mouse M2 macrophage marker, was further upregulated by deletion of Tim-1. Together, these results show that Tim-1 deficiency aggravates the effects of HFD diet on lipid accumulation and liver fibrosis, most likely through enhanced infiltration and activation of inflammatory cells.

Comprehensive Analysis of the Expression, Relationship to Immune Infiltration and Prognosis of TIM-1 in Cancer

TIM-1 is a critical gene that regulates T-helper cell development. However, little research has revealed the distribution, prognosis, and immune infiltration of TIM-1 in cancers. TCGA, GEO, Oncomine, TIMER, Kaplan-Meier, PrognoScan, GEPIA, TISIDB, and HPA databases were used to analyze TIM-1 in cancers. High TIM-1 expression was observed in bladder, cholangio, head and neck, colorectal, gastric, kidney, liver, lung adenocarcinoma, skin, uterine corpus endometrial, and pancreatic cancers compared to the normal tissues, and immunofluorescence shows that TIM-1 is mainly localized in vesicles. Simultaneously, high TIM-1 expression was closely related with poorer overall survival in gastric, lung adenocarcinoma, and poorer disease-specific survival in gastric cancer in the TCGA cohort, and was validated in the GEO cohort. Moreover, high expression of TIM-1, correlated with clinical relevance of gastric cancer and lung adenocarcinoma, was associated with tumor-infiltrating lymphocytes in lung adenocarcinoma and gastric cancer. Finally, immunohistochemistry showed TIM-1 expression was higher in lung adenocarcinoma and gastric cancer compared to the normal tissues. In summary, we applied integrated bioinformatics approaches to suggest that TIM-1 can be used as a prognostic biomarker in gastric and lung adenocarcinoma, which might provide a novel direction to explore the pathogenesis of gastric and lung adenocarcinoma.

Role of Co-stimulatory Molecules in T Helper Cell Differentiation

CD4⁺ T cells play a central role in orchestrating the immune response to a variety of pathogens but also regulate autoimmune responses, asthma, allergic responses, as well as tumor immunity. To cover this broad spectrum of responses, naïve CD4⁺ T cells differentiate into one of several lineages of T helper cells, including Th1, Th2, Th17, and T_FH, as defined by their cytokine pattern and function. The fate decision of T helper cell differentiation integrates signals delivered through the T cell receptor, cytokine receptors, and the pattern of co-stimulatory signals received. In this review, we summarize the contribution of co-stimulatory and co-inhibitory receptors to the differentiation and maintenance of T helper cell responses.

Role of Transmembrane Protein 16F in the Incorporation of Phosphatidylserine Into Budding Ebola Virus Virions

Viral apoptotic mimicry, which is defined by exposure of phosphatidylserine (PtdSer) into the outer leaflet of budding enveloped viruses, increases viral tropism, infectivity and promotes immune evasion. Here, we report that the calcium (Ca2+)-dependent scramblase, transmembrane protein 16F (TMEM16F), is responsible for the incorporation of PtdSer into virion membranes during Ebola virus infection. Infection of Huh7 cells with Ebola virus resulted in a pronounced increase in plasma membrane-associated PtdSer, which was demonstrated to be dependent on TMEM16F function. Analysis of virions using imaging flow cytometry revealed that short hairpin RNA-mediated down-regulation of TMEM16F function directly reduced virion-associated PtdSer. Taken together, these studies demonstrate that TMEM16F is a central cellular factor in the exposure of PtdSer in the outer leaflet of viral membranes.

Fine Particulate Matter-Induced Exacerbation of Allergic Asthma via Activation of T-cell Immunoglobulin and Mucin Domain 1

Background:

Fine particulate matter (PM_2.5) exacerbates airway inflammation and hyperreactivity in patients with asthma, but the mechanism remains unclear. The aim of this study was to observe the effects of prolonged exposure to high concentrations of PM_2.5 on the pathology and airway hyperresponsiveness (AHR) of BALB/c mice undergoing sensitization and challenge with ovalbumin (OVA) and to observe the effects of apoptosis and T-cell immunoglobulin and mucin domain 1 (TIM-1) in this process.

Methods:

Forty female BALB/c mice were divided into four groups: control group, OVA group, OVA/PM group, and PM group (n = 10 in each group). Mice in the control group were exposed to filtered clean air. Mice in the OVA group were sensitized and challenged with OVA. Mice in the OVA/PM group were sensitized and challenged as in the OVA group and then exposed to PM_2.5 for 4 h per day and 5 days per week for a total of 8 weeks using a nose-only “PM_2.5 online enrichment system” in The Second Hospital of Hebei Medical University. Mice in the PM group were exposed to the PM_2.5 online enrichment system only. AHR was detected. Bronchoalveolar lavage fluid (BALF) was collected for cell classification. The levels of interleukin-4 (IL-4), IL-5, and IL-33 in BALF were measured using enzyme-linked immunosorbent assay. Changes in histological structures were examined by light microscopy, and changes in ultramicrostructures were detected by electron microscopy. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay in the lung tissues. Western blotting and immunohistochemistry were utilized to analyze the expression of Bcl-2, Bax, and TIM-1 in the lungs.

Results:

The results showed that AHR in the OVA/PM group was significantly more severe than that in the OVA and PM groups (P < 0.05). AHR in the PM group was also considerably more severe than that in the control group (P < 0.05). The BALF of OVA/PM group (28.00 ± 6.08 vs. 12.33 ± 4.51, t = 4.631, P = 0.002) and PM group (29.00 ± 3.00 vs. 12.33 ± 4.51, t = 4.927, P = 0.001) had more lymphocytes than the BALF of the control group. The number of neutrophils in the BALF of the OVA/PM group (6.67 ± 1.53 vs. 3.33 ± 1.53, t = 2.886, P = 0.020) and PM group (6.67 ± 1.53 vs. 3.33 ± 1.53, t = 2.886, P = 0.020) was much higher than those in the BALF of OVA group (P < 0.05). TUNEL assays showed that the number of apoptotic cells in the OVA/PM group was significantly higher than that in the OVA group (Tunel immunohistochemical scores [IHS%], 1.20 ± 0.18 vs. 0.51 ± 0.03, t = 8.094, P < 0.001) and PM group (Tunel IHS%, 1.20 ± 0.18 vs. 0.51 ± 0.09, t = 8.094, P < 0.001), and that the number of apoptotic cells in the PM group was significantly higher than that in the control group (Tunel IHS%, 0.51 ± 0.09 vs. 0.26 ± 0.03, t = 2.894, P = 0.020). The concentrations of IL-4 (77.44 ± 11.19 vs. 48.02 ± 10.02 pg/ml, t = 4.595, P = 0.002) and IL-5 (15.65 ± 1.19 vs. 12.35 ± 0.95 pg/ml, t = 3.806, P = 0.005) and the Bax/Bcl-2 ratio (1.51 ± 0.18 vs. 0.48 ± 0.10, t = 9.654, P < 0.001) and TIM-1/β-actin ratio (0.78 ± 0.11 vs. 0.40 ± 0.06, t = 6.818, P < 0.001) in the OVA/PM group were increased compared to those in the OVA group. The concentrations of IL-4 (77.44 ± 11.19 vs. 41.47 ± 3.40 pg/ml, t = 5.617, P = 0.001) and IL-5 (15.65 ± 1.19 vs. 10.99 ± 1.40 pg/ml, t = 5.374, P = 0.001) and the Bax/Bcl-2 ratio (1.51 ± 0.18 vs. 0.97 ± 0.16, t = 5.000, P = 0.001) and TIM-1/β-actin ratio (0.78 ± 0.11 vs. 0.31 ± 0.06, t = 8.545, P < 0.001) in the OVA/PM group were increased compared to those in the PM group. The concentration of IL-4 (41.47 ± 3.40 vs. 25.46 ± 2.98 pg/ml, t = 2.501, P = 0.037) and the Bax/Bcl-2 ratio (0.97 ± 0.16 vs. 0.18 ± 0.03, t = 7.439, P < 0.001) and TIM-1/β-actin ratio (0.31 ± 0.06 vs. 0.02 ± 0.01, t = 5.109, P = 0.001) in the PM group were also higher than those in the control group.

Conclusions:

Exacerbated AHR associated with allergic asthma caused by PM_2.5 is related to increased apoptosis and TIM-1 activation. These data might provide insights into therapeutic targets for the treatment of acute exacerbations of asthma induced by PM_2.5.

The effects of resiquimod in an ovalbumin-induced allergic rhinitis model

Growing evidence indicates that the Toll-like receptor7/8(TLR7/8) agonist resiquimod (R848) is a potential inhibitor of type-2 immunity. However, the mechanisms mediating its therapeutic effects are not fully understood. This study investigated the effects of R848 on OVA-induced allergic rhinitis(AR) mice and the expression of IL-25, IL-33, TSLP, T-cell immunoglobulin mucin1 (TIM1) and T-cell immunoglobulin mucin3 (TIM3). BALB/c mice were intranasally sensitized and challenged with ovalbumin (OVA), and R848 was intraperitoneally injected into AR mice. Histological changes in the nasal mucosa were evaluated by hematoxylin and eosin (H & E) and Periodic Acid-Schiff (PAS) staining; cytokine levels in serum were measured with enzyme-linked immunosorbent assays (ELISAs);the mRNA expression levels of IFN-γ, IL-17 and Foxp3 in the spleen determined by quantitative real-time RT-PCR (qRT-PCR); the proportions of Th1, Th2, Th17, Treg and TIM3 + IFN-γ + Th1 cells in the spleen were assessed with flow cytometry; TIM1, TIM3 and IL-33 expression levels in the nasal mucosa were evaluated with immunofluorescence staining(IF).R848 alleviated the nasal allergic symptoms; reduced eosinophil cell infiltration, goblet cell hyperplasia in the nasal mucosa; reduced IL-13, IL-17, IL-25 and IL-33 levels in serum; upregulated the relative mRNA expression of IFN-γ and Foxp3, and downregulated the relative mRNA expression of IL-17 in the spleen; decreased Th2, Th17 and TIM3 + IFN-γ + Th1 cells ratios, increased the proportion of Th1 and Treg cells in the spleen; suppressed TIM1 and TIM3,but increased IL-33 expression in the nasal mucosa in OVA-induced AR mice. R848 suppresses IL-25, IL-33 released and TIM1, TIM3 expression, which may contribute to its anti-allergic effects.

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.

Development of a Stable Cell Line, Overexpressing Human T-cell Immunoglobulin Mucin 1

BACKGROUND

Recent researches have demonstrated that human T-cell immunoglobulin mucin 1 (TIM-1) glycoprotein plays important roles in regulation of autoimmune and allergic diseases, as well as in tumor immunity and response to viral infections. Therefore, targeting TIM-1 could be a potential therapeutic approach against such diseases.

OBJECTIVES

In this study, we aimed to express TIM-1 protein on Human Embryonic kidney (HEK) 293T cell line in order to have an available source of the TIM-1 antigen.

MATERIALS AND METHODS

The cDNA was synthesized after RNA extraction from peripheral blood mononuclear cells (PBMC) and TIM-1 cDNA was amplified by PCR with specific primers. The PCR product was cloned in pcDNA™3.1/Hygro (+) and transformed in Escherichia coli TOP 10 F'. After cloning, authenticity of DNA sequence was checked and expressed in HEK 293T cells. Finally, expression of TIM-1 was analyzed by flow cytometry and real-time PCR.

RESULTS

The result of DNA sequencing demonstrated correctness of TIM-1 DNA sequence. The flow cytometry results indicated that TIM-1 was expressed in about 90% of transfected HEK 293T cells. The real-time PCR analysis showed TIM-1 mRNA expression increased 195-fold in transfected cells compared with un-transfected cells.

CONCLUSIONS

Findings of present study demonstrated the successful cloning and expression of TIM-1 on HEK 293T cells. These cells could be used as an immunogenic source for production of specific monoclonal antibodies, nanobodies and aptamers against human TIM-1.

Blocking monoclonal antibodies of TIM proteins as orchestrators of anti-tumor immune response

Monoclonal antibody (mAb)-based treatment of cancer has a significant effect on current practice in medical oncology, and is considered now as one of the most successful therapeutic strategies for cancer treatment. MAbs are designed to initiate or enhance anti-tumor immune responses, which can be achieved by either blocking inhibitory immune checkpoint molecules or triggering activating receptors. TIM gene family members are type-I surface molecules expressed in immune cells, and play important roles in the regulation of both innate and adaptive arms of the immune system. Therapeutic strategies based on anti-TIMs mAbs have shown promising results in experimental tumor models, and synergistic combinations of anti-TIMs mAbs with cancer vaccines, adoptive T-cell therapy, radiotherapy and chemotherapy will have great impact on cancer treatment in future clinical development.

Protective association of TIM1-1454G>a polymorphism with asthma in a North Indian population

PURPOSE

TIM1 is a key regulator of Th2-dominated immune responses, including allergy, asthma, autoimmunity, and response to the pathogens. They are mainly expressed by hepatocytes and lymphoid cells. Analysis of the sequence of TIM1 was found to have range of SNPs which increases the transcriptional activity of the TIM1 gene.

METHODS

A case-control study was conducted with a total of 964 subjects, including 483 healthy controls and 481 asthma patients in the present study. DNA samples were extracted from blood, and genotyping was done using polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

Statistical analysis revealed that both heterozygous (GA) as well as the mutant (AA) genotype of -1454G>A (rs41297579) polymorphism shows resistance toward asthma with OR = 0.74, 95 % CI (0.55-0.98), p = 0.029 and OR = 0.43, 95 % CI (0.28-0.65), p = 0.000, respectively. The mutant (A) allele was also found to be highly protective toward asthma with OR = 0.68, 95 % CI (0.56-0.82) p = 0.000. However, no statistical difference was found between the TIM1-416G>C (rs9313422) polymorphism and asthma patients (p > 0.05).

CONCLUSIONS

This is the first study conducted in India conferring -1454G>A polymorphism provides resistance toward asthma while lack of association was found between -416G>C polymorphism and asthma in the studied North Indian population.

The impact of the TIM gene family on tumor immunity and immunosuppression

Tumor immunoevasion is an advanced phase of cancer immunosurveillance in which tumor cells acquire the ability to circumvent host immune systems and exploit protumorigenic inflammation. T-cell immunoglobulin mucin (TIM) gene family members have emerged as critical checkpoint proteins that regulate multiple immune response phases and maintain immune homeostasis. Accumulating evidence demonstrates that tumor cells exploit TIM gene family members to evade immunosurveillance, whereas TIM gene family members facilitate the prevention of inflammation-related tumor progression. Thus, a comprehensive analysis to clarify the relative contributions of TIM gene family members in tumor progression may elucidate immunosurveillance systems in cancer patients.

T-cell immunoglobulin and mucin domain 1 deficiency eliminates airway hyperreactivity triggered by the recognition of airway cell death

BACKGROUND

Studies of asthma have been limited by a poor understanding of how nonallergic environmental exposures, such as air pollution and infection, are translated in the lung into inflammation and wheezing.

OBJECTIVE

Our goal was to understand the mechanism of nonallergic asthma that leads to airway hyperreactivity (AHR), a cardinal feature of asthma independent of adaptive immunity.

METHOD

We examined mouse models of experimental asthma in which AHR was induced by respiratory syncytial virus infection or ozone exposure using mice deficient in T-cell immunoglobulin and mucin domain 1 (TIM1/HAVCR1), an important asthma susceptibility gene.

RESULTS

TIM1(-/-) mice did not have airways disease when infected with RSV or when repeatedly exposed to ozone, a major component of air pollution. On the other hand, the TIM1(-/-) mice had allergen-induced experimental asthma, as previously shown. The RSV- and ozone-induced pathways were blocked by treatment with caspase inhibitors, indicating an absolute requirement for programmed cell death and apoptosis. TIM-1-expressing, but not TIM-1-deficient, natural killer T cells responded to apoptotic airway epithelial cells by secreting cytokines, which mediated the development of AHR.

CONCLUSION

We defined a novel pathway in which TIM-1, a receptor for phosphatidylserine expressed by apoptotic cells, drives the development of asthma by sensing and responding to injured and apoptotic airway epithelial cells.

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

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

Tim-1 regulates Th2 responses in an airway hypersensitivity model

T-cell immunoglobulin mucin-1 (Tim-1) is a transmembrane protein postulated to be a key regulator of Th2-type immune responses. This hypothesis is based in part upon genetic studies associating Tim-1 polymorphisms in mice with a bias toward airway hyperrespon-siveness (AHR) and the development of Th2-type CD4(+) T cells. Tim-1 expressed by Th2 CD4(+) T cells has been proposed to function as a co-stimulatory molecule. Tim-1 is also expressed by B cells, macrophages, and dendritic cells, but its role in responses by these cell types has not been firmly established. Here, we generated Tim-1-deficient mice to determine the role of Tim-1 in a murine model of allergic airway disease that depends on the development and function of Th2 effector cells and results in the generation of AHR. We found antigen-driven recruitment of inflammatory cells into airways is increased in Tim-1-deficient mice relative to WT mice. In addition, we observed increased antigen-specific cytokine production by splenocytes from antigen-sensitized Tim-1-deficient mice relative to those from controls. These data support the conclusion that Tim-1 functions in pathways that suppress recruitment of inflammatory cells into the airways and the generation or activity of CD4(+) T cells.

Allergic asthma: influence of genetic and environmental factors

Allergic asthma is a chronic airway inflammatory disease in which exposure to allergens causes intermittent attacks of breathlessness, airway hyper-reactivity, wheezing, and coughing. Allergic asthma has been called a "syndrome" resulting from a complex interplay between genetic and environmental factors. Worldwide, >300 million individuals are affected by this disease, and in the United States alone, it is estimated that >35 million people, mostly children, suffer from asthma. Although animal models, linkage analyses, and genome-wide association studies have identified numerous candidate genes, a solid definition of allergic asthma has not yet emerged; however, such studies have contributed to our understanding of the multiple pathways to this syndrome. In contrast with animal models, in which T-helper 2 (T(H)2) cell response is the dominant feature, in human asthma, an initial exposure to allergen results in T(H)2 cell-dependent stimulation of the immune response that mediates the production of IgE and cytokines. Re-exposure to allergen then activates mast cells, which release mediators such as histamines and leukotrienes that recruit other cells, including T(H)2 cells, which mediate the inflammatory response in the lungs. In this minireview, we discuss the current understanding of how associated genetic and environmental factors increase the complexity of allergic asthma and the challenges allergic asthma poses for the development of novel approaches to effective treatment and prevention.

Suppression of allograft rejection by Tim-1-Fc through cross-linking with a novel Tim-1 binding partner on T cells

Engagement of T-cell immunoglobulin mucin (Tim)-1 on T cells with its ligand, Tim-4, on antigen presenting cells delivers positive costimulatory signals to T cells. However, the molecular mechanisms for Tim-1-mediated regulation of T-cell activation and differentiation are relatively poorly understood. Here we investigated the role of Tim-1 in T-cell responses and allograft rejection using recombinant human Tim-1 extracellular domain and IgG1-Fc fusion proteins (Tim-1-Fc). In vitro assays confirmed that Tim-1-Fc selectively binds to CD4⁺ effector T cells, but not dendritic cells or natural regulatory T cells (nTregs). Tim-1-Fc was able to inhibit the responses of purified CD4⁺ T cells that do not express Tim-4 to stimulation by anti-CD3/CD28 mAbs, and this inhibition was associated with reduced AKT and ERK1/2 phosphorylation, but it had no influence on nTregs. Moreover, Tim-1-Fc inhibited the proliferation of CD4⁺ T cells stimulated by allogeneic dendritic cells. Treatment of recipient mice with Tim-1-Fc significantly prolonged cardiac allograft survival in a fully MHC-mismatched strain combination, which was associated with impaired Th1 response and preserved Th2 and nTregs function. Importantly, the frequency of Foxp3⁺ cells in splenic CD4⁺ T cells was increased, thus shifting the balance toward regulators, even though Tim-1-Fc did not induce Foxp3 expression in CD4⁺CD25⁻ T cells directly. These results indicate that Tim-1-Fc can inhibit T-cell responses through an unknown Tim-1 binding partner on T cells, and it is a promising immunosuppressive agent for preventing allograft rejection.

Tim1 and Tim3 are not essential for experimental allergic asthma

Background

Initial studies suggested that polymorphisms in Tim1 and Tim3 contribute to the development of airway hyperreactivity (AHR) in an acute mouse model of asthma. This was also mirrored in human genetic studies where polymorphisms in Tim1 and Tim3 have been associated with atopic populations.

Objective

Further studies using anti-Tim1 or -Tim3 antibodies, or Tim fusion proteins, have also suggested that these molecules may function as regulators of type-1 and type-2 immunity. However, their role in the development of AHR and airway inflammation remains unclear. Given the proposed roles for Tim1 and Tim3 in type-1 and type-2 responses, we sought to determine whether these molecules were important in regulating antigen-driven lung allergy and inflammation.

Method

We used Tim1- and Tim3-deficient mice and determined how the development of allergic lung inflammation was affected.

Results

AHR was induced normally in the absence of both Tim1 and Tim3, although Tim1-deficient mice did show a small but significant decrease in cell infiltration in the lung and blood eosinophilia. Although Tim3 was expressed on CD4⁺ T cells in the allergic lung, Tim1 expression was restricted to CD86⁺ B cells.

Conclusions and clinical relevance

Thus, Tim1 and Tim3 are not essential for the induction of the type-2 response in lung allergy. This is contrary to what was proposed in a number of other studies using neutralizing and activating antibodies and questions the clinical relevance of Tim1 and Tim3 for novel allergy therapies.

Cite this as: J. L. Barlow, S. H. Wong, S. J. Ballantyne, H. E. Jolin and A. N. J. McKenzie, Clinical & Experimental Allergy, 2011 (41) 1012–1021.

Dysregulation of TIM-3-galectin-9 pathway in the cystic fibrosis airways

The T-cell Ig and mucin domain-containing molecules (TIMs) have emerged as promising therapeutic targets to correct abnormal immune function in several autoimmune and chronic inflammatory conditions. It has been reported that proinflammatory cytokine dysregulation and neutrophil-dominated inflammation are the main causes of morbidity in cystic fibrosis (CF). However, the role of TIM receptors in CF has not been investigated. In this study, we demonstrated that TIM-3 is constitutively overexpressed in the human CF airway, suggesting a link between CF transmembrane conductance regulator (CFTR) function and TIM-3 expression. Blockade of CFTR function with the CFTR inhibitor-172 induced an upregulation of TIM-3 and its ligand galectin-9 in normal bronchial epithelial cells. We also established that TIM-3 serves as a functional receptor in bronchial epithelial cells, and physiologically relevant concentrations of galectin-9 induced TIM-3 phosphorylation, resulting in increased IL-8 production. In addition, we have demonstrated that both TIM-3 and galectin-9 undergo rapid proteolytic degradation in the CF lung, primarily because of neutrophil elastase and proteinase-3 activity. Our results suggest a novel intrinsic defect that may contribute to the neutrophil-dominated immune response in the CF airways.

Apoptotic cells activate NKT cells through T cell Ig-like mucin-like-1 resulting in airway hyperreactivity

T cell Ig-like mucin-like-1 (TIM-1) is an important asthma susceptibility gene, but the immunological mechanisms by which TIM-1 functions remain uncertain. TIM-1 is also a receptor for phosphatidylserine (PtdSer), an important marker of cells undergoing programmed cell death, or apoptosis. We now demonstrate that NKT cells constitutively express TIM-1 and become activated by apoptotic cells expressing PtdSer. TIM-1 recognition of PtdSer induced NKT cell activation, proliferation, and cytokine production. Moreover, the induction of apoptosis in airway epithelial cells activated pulmonary NKT cells and unexpectedly resulted in airway hyperreactivity, a cardinal feature of asthma, in an NKT cell-dependent and TIM-1-dependent fashion. These results suggest that TIM-1 serves as a pattern recognition receptor on NKT cells that senses PtdSer on apoptotic cells as a damage-associated molecular pattern. Furthermore, these results provide evidence for a novel innate pathway that results in airway hyperreactivity and may help to explain how TIM-1 and NKT cells regulate asthma.

Specific immunotherapy suppresses Th2 responses via modulating TIM1/TIM4 interaction on dendritic cells

BACKGROUND

Specific immunotherapy (SIT) is the only curable remedy for allergic disorders currently; however, the underlying mechanism is not fully understood yet. This study aimed to elucidate the mechanism of SIT on suppressing TIM4 (T cell immunoglobulin mucin domain molecule 4) expression in dendritic cells (DCs) and modulating the skewed T helper 2 (Th2) responses in patients with airway allergy.

METHODS

Twenty patients with allergic rhinitis (AR) were treated with SIT for 3 months. Before and after SIT, the expression of TIM4 in peripheral DC and TIM1 in Th2 cells was examined. The role of Fc gamma receptor (FcgammaR) I and II in modulating the expression of TIM4 in DCs was investigated.

RESULTS

The interaction of TIM1/TIM4 played a critical role in sustaining the polarization status of Th2 cells in AR patients. Cross-linking FcgammaRI by antigen/IgG complexes increased the production of TIM4 by dendritic cells via upregulating tumor necrosis factor-alpha in DCs. Exposure to microbial products promoted the expression of FcgammaRI in DCs that further increased the expression of TIM4. Exposure to specific antigens alone upregulated the expression of FcgammaRII in DCs, that suppressed the expression of TIM4.

CONCLUSIONS

We conclude that SIT suppresses the skewed Th2 responses via disrupting the interaction of TIM1/TIM4 in antigen-specific Th2 cells.

TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity

The TIM (T cell/transmembrane, immunoglobulin, and mucin) gene family plays a critical role in regulating immune responses, including allergy, asthma, transplant tolerance, autoimmunity, and the response to viral infections. The unique structure of TIM immunoglobulin variable region domains allows highly specific recognition of phosphatidylserine (PtdSer), exposed on the surface of apoptotic cells. TIM-1, TIM-3, and TIM-4 all recognize PtdSer but differ in expression, suggesting that they have distinct functions in regulating immune responses. TIM-1, an important susceptibility gene for asthma and allergy, is preferentially expressed on T-helper 2 (Th2) cells and functions as a potent costimulatory molecule for T-cell activation. TIM-3 is preferentially expressed on Th1 and Tc1 cells, and generates an inhibitory signal resulting in apoptosis of Th1 and Tc1 cells. TIM-3 is also expressed on some dendritic cells and can mediate phagocytosis of apoptotic cells and cross-presentation of antigen. In contrast, TIM-4 is exclusively expressed on antigen-presenting cells, where it mediates phagocytosis of apoptotic cells and plays an important role in maintaining tolerance. TIM molecules thus provide a functional repertoire for recognition of apoptotic cells, which determines whether apoptotic cell recognition leads to immune activation or tolerance, depending on the TIM molecule engaged and the cell type on which it is expressed.

TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity

The TIM (T cell/transmembrane, immunoglobulin, and mucin) gene family plays a critical role in regulating immune responses, including allergy, asthma, transplant tolerance, autoimmunity, and the response to viral infections. The unique structure of TIM immunoglobulin variable region domains allows highly specific recognition of phosphatidylserine (PtdSer), exposed on the surface of apoptotic cells. TIM-1, TIM-3, and TIM-4 all recognize PtdSer but differ in expression, suggesting that they have distinct functions in regulating immune responses. TIM-1, an important susceptibility gene for asthma and allergy, is preferentially expressed on T-helper 2 (Th2) cells and functions as a potent costimulatory molecule for T-cell activation. TIM-3 is preferentially expressed on Th1 and Tc1 cells, and generates an inhibitory signal resulting in apoptosis of Th1 and Tc1 cells. TIM-3 is also expressed on some dendritic cells and can mediate phagocytosis of apoptotic cells and cross-presentation of antigen. In contrast, TIM-4 is exclusively expressed on antigen-presenting cells, where it mediates phagocytosis of apoptotic cells and plays an important role in maintaining tolerance. TIM molecules thus provide a functional repertoire for recognition of apoptotic cells, which determines whether apoptotic cell recognition leads to immune activation or tolerance, depending on the TIM molecule engaged and the cell type on which it is expressed.

Antagonism of TIM-1 blocks the development of disease in a humanized mouse model of allergic asthma

Studies in mice and humans have revealed that the T cell, immunoglobulin, mucin (TIM) genes are associated with several atopic diseases. TIM-1 is a type I membrane protein that is expressed on T cells upon stimulation and has been shown to modulate their activation. In addition to a recently described interaction with dendritic cells, TIM-1 has also been identified as a phosphatidylserine recognition molecule, and several protein ligands have been proposed. Our understanding of its activity is complicated by the possibility that TIM-1 possesses multiple and diverse binding partners. In order to delineate the function of TIM-1, we generated monoclonal antibodies directed to a cleft formed within the IgV domain of TIM-1. We have shown here that antibodies that bind to this defined cleft antagonize TIM-1 binding to specific ligands and cells. Notably, these antibodies exhibited therapeutic activity in a humanized SCID model of experimental asthma, ameliorating inflammation, and airway hyperresponsiveness. Further experiments demonstrated that the effects of the TIM-1-specific antibodies were mediated via suppression of Th2 cell proliferation and cytokine production. These results demonstrate that modulation of the TIM-1 pathway can critically influence activated T cells in a humanized disease model, suggesting that TIM-1 antagonists may provide potent therapeutic benefit in asthma and other immune-mediated disorders.

Tim-1 is induced on germinal centre B cells through B-cell receptor signalling but is not essential for the germinal centre response

T-cell immunoglobulin mucin-1 (Tim-1) has been proposed to be an important T-cell immunoregulatory molecule since its expression on activated T cells was discovered. To study the role of Tim-1 on T cells in vitro and in vivo we generated both Tim-1-deficient mice and several lines of Tim-1 transgenic mice with Tim-1 expression on either T cells, or B and T cells. We demonstrate that neither deficiency nor over-expression of Tim-1 on B and T cells results in modulation of their proliferation in vitro. More surprisingly, T helper type 2 cells generated either from Tim-1-deficient mice or Tim-1 transgenic mice did not show enhancement of interleukin-4 (IL-4), IL-5 and IL-10 production. Furthermore, using a Schistosoma mansoni egg challenge as a potent T helper type 2 response inducer we also show that Tim-1 is not essential for T- and B-cell responses in vivo. However, we observe induction of Tim-1 on B cells following B-cell receptor (BCR), but not Toll-like receptor 4 stimulation in vitro. We show that the induction of Tim-1 on B cells following BCR stimulation is phosphoinositide-3 kinase and nuclear factor-kappaB pathway dependent. More importantly, we conclude that Tim-1 is predominantly expressed on germinal centre B cells in vivo although the percentage of germinal centre B cells in wild-type and Tim-1-deficient mice is comparable. Identification of Tim-1 as a marker for germinal centre B cells will contribute to the interpretation and future analysis of the effects of the anti-Tim-1 antibodies in vivo.

99th Dahlem conference on infection, inflammation and chronic inflammatory disorders: microbes, apoptosis and TIM-1 in the development of asthma

Asthma is a complex disorder which has increased dramatically in prevalence over the past three decades. Current therapies, based on the T helper type 2 (Th2) paradigm, have not been able to control this disease. Epidemiological studies have demonstrated an association between infection with the hepatitis A virus (HAV) and protection against the development of asthma, and genetic studies have shown that the HAV receptor, TIM-1 (T cell, immunoglobulin domain and mucin domain), is an important atopy susceptibility gene. Furthermore, recent studies indicate that TIM-1 is a receptor for phosphatidylserine, an important marker of apoptotic cells. These studies together suggest that HAV and TIM-1 may potently regulate asthma through novel non-Th2-mediated mechanisms. Further study of the immunobiology of TIM-1 and its involvement in the clearance of apoptotic cells is likely to provide important insight into the mechanisms that lead to, and those that protect against, asthma, and how infection affects immunity and the development of asthma.

T cell Ig domain and mucin domain 1 engagement on invariant NKT cells in the presence of TCR stimulation enhances IL-4 production but inhibits IFN-gamma production

The T cell Ig domain and mucin domain (TIM)1 protein expressed on the surface of Th2 cells regulates the immune response by modulating cytokine production. However, the functional roles of TIM1 have not been examined in NKT cells. Therefore, we investigated the immunologic effects of TIM1 on NKT cells. We found that mouse NK1.1(+)TCR-beta(+), alpha-galactosyl ceramide/CD1d dimer(+) NKT, and NKT hybridoma (DN32.D3) cells constitutively express TIM1 and TIM4 on their surface. Engagement of TIM1 on NKT cells by any of several anti-TIM1 mAbs suppressed the production of IFN-gamma in the presence of TCR stimulation in vitro and in vivo, whereas the effects of such engagement on Th2 cytokine production by the NKT cells varied with the particular anti-TIM1 Ab clone. Moreover, in DN32.D3 TIM4-knockdown NKT hybridoma cells, TIM1 engagement by rTIM1 or TIM4 enhanced IL-4 production while inhibiting IFN-gamma production in the presence of alpha-galactosyl ceramide stimulation. TIM1 engagement increased GATA-3 expression but reduced T-bet expression in NKT cells in the presence of TCR engagement. The adoptive transfer of NKT cells preincubated with anti-TIM1 mAbs into Jalpha18(-/-) mice aggravated bleomycin-induced pulmonary fibrosis by suppressing IFN-gamma production. Taken together, these results suggest that TIM1 costimulation on NKT cells enhances the cellular production of IL-4 while inhibiting the production of IFN-gamma. Thus, as a differential regulator of the immune response, TIM1 on NKT cells may be a useful therapeutic target for immune diseases.

Altered expression of T cell immunoglobulin-mucin (TIM) molecules in bronchoalveolar lavage CD4+ T cells in sarcoidosis

BACKGROUND

Activated T helper (Th)-1 pulmonary CD4+ cells and their mediators are essential for the inflammation and granulomatous process in sarcoidosis. Recently, T-cell immunoglobulin and mucin domain (TIM) molecules were suggested to be important regulators of immune function. In this study, we wanted to investigate whether TIM molecules could play a role in sarcoidosis.

METHODS

We used real-time polymerase chain reaction to investigate the differential gene expression of TIM-1 and TIM-3 as well as a few Th1 and Th2 cytokines (IL-2, IFN-gamma, IL-4, IL-5 and IL-13) in CD4+ T cells isolated from bronchoalveolar lavage fluid (BALF) of patients (n = 28) and healthy controls (n = 8). Using flow cytometry, we were also able to analyse TIM-3 protein expression in 10 patients and 6 healthy controls.

RESULTS

A decreased TIM-3 mRNA (p < 0.05) and protein (p < 0.05) expression was observed in patients, and the level of TIM-3 mRNA correlated negatively with the CD4/CD8 T cell ratio in BALF cells of patients. Compared to a distinct subgroup of patients i.e. those with Löfgren's syndrome, BALF CD4+ T cells from non- Löfgren's patients expressed decreased mRNA levels of TIM-1 (p < 0.05). mRNA expression of IL-2 was increased in patients (p < 0.01) and non-Löfgren's patients expressed significantly higher levels of IFN-gamma mRNA (p < 0.05) versus patients with Löfgren's syndrome.

CONCLUSION

These findings are the first data on the expression of TIM-1 and TIM-3 molecules in sarcoidosis. The reduced TIM-3 expression in the lungs of patients may result in a defective T cell ability to control the Th1 immune response and could thus contribute to the pathogenesis of sarcoidosis. The down-regulated TIM-1 expression in non-Löfgren'spatients is in agreement with an exaggerated Th1 response in these patients.

T cell Ig and mucin domain-1-mediated T cell activation requires recruitment and activation of phosphoinositide 3-kinase

Ligation of the transmembrane protein T cell Ig and mucin domain (Tim)-1 can costimulate T cell activation. Agonistic Abs to Tim-1 are also capable of inducing T cell activation without additional stimuli. However, little is known about the biochemical mechanisms underlying T cell stimulation or costimulation through Tim-1. We show that a tyrosine in Tim-1 becomes phosphorylated in a lck-dependent manner, whereupon it can directly recruit p85 adaptor subunits of PI3K. This results in PI3K activation, which is required for Tim-1 function. We also provide genetic evidence that p85 expression is required for optimal Tim-1 function. Thus, we describe a pathway from Tim-1 tyrosine phosphorylation to the PI3K signaling pathway, which appears to be a major effector of Tim-1-mediated T cell activation.

Galectin-9 suppresses the generation of Th17, promotes the induction of regulatory T cells, and regulates experimental autoimmune arthritis

The effects of galectin-9 on a mouse collagen-induced arthritis (CIA) model were assessed to clarify whether galectin-9 suppresses CIA by regulating T cell immune responses. Galectin-9 suppressed CIA in a dose-dependent manner, and such suppression was observed even when treatment was started on 7 days after the booster, indicating its preventive and therapeutic effects. Galectin-9 induced the decreased levels of pro-inflammatory cytokines, IL-17, IL-12, and IFNgamma in the joint. Galectin-9 induced the decreased number of CD4(+) TIM-3(+) T cells in peripheral blood. Galectin-9-deficient mice became susceptible to CIA may be by increased number of CD4(+) TIM-3(+) T cells and decreased number of Treg cells. We further found that galectin-9 induces differentiation of naive T cells to Treg cells, and it suppresses differentiation to Th17 cells in vitro. The present results suggested that galectin-9 ameliorates CIA by suppressing the generation of Th17, promoting the induction of regulatory T cells.

The role of the T-cell costimulatory molecule Tim-1 in the immune response

Upon encountering antigen, CD4+ T-cells become activated and can differentiate into subsets with distinct functional characteristics. One of these subsets is the Th2 cell, which generates large amounts of interleukin (IL)-4, -5, -10 and -13 in response to a subsequent encounter with antigen. In the context of a protective immune response, Th2 cells promote immune cell activation, antibody production, and inflammatory responses that help clear infections. However, aberrant responses by Th2 cells can lead to debilitating allergic diseases such as asthma. Thus, a reasonable approach toward gaining novel insights into immunity and allergic disease is to define the mechanisms that control Th2 cell differentiation and mature Th2 cell function. Recent work suggests that a protein called Tim-1 (T-cell immunoglobulin and mucin protein-1) is expressed on CD4+ T-cells and plays a central role in regulating Th2 responses. Genetic analysis has linked polymorphisms in the human TIM1 gene to susceptibility to allergic disease, while studies involving mice have shown that ligation of Tim-1 promotes CD4+ T-cell activation. The signal transduction pathways downstream of Tim-1 are a relatively unexplored area. Continued study will undoubtedly reveal novel insights regarding the relationships between Tim-1, Th2 responses, and allergic disease.

Expression of T-cell immunoglobulin- and mucin-domain-containing molecule-1 (TIM-1) is increased in a mouse model of asthma and relationship to GATA-3

It has been suggested that T-cell immunoglobulin-and mucin-domain-containing molecule-1 (TIM-1) plays an important role in the development of allergic asthma, though its molecular mechanism remains unclear. Our aim was to examine the expression of TIM-1 and Th2-associated transcription factor GATA-3 in asthmatic mice, and to evaluate the correlation of TIM-1 and GATA-3 in the pathogenesis of allergic asthma. We examined TIM-1 expression in lung tissue and peripheral blood mononuclear cells (PBMCs) of asthmatic mice by real-time PCR and flow cytometry, respectively; we also investigated TIM-1 and GATA-3 expression in the spleen tissue of asthmatic mice by western blot. These results demonstrate that TIM-1 was significantly increased in pulmonary tissues and PBMCs in asthmatic mice after ovalbumin (OVA) challenge (P<0.05), and that the production of TIM-1 as well as GATA-3 was upregulated in the spleen of asthmatic mice. The production of TIM-1 correlated significantly with the production of GATA-3 in the spleen of asthmatic mice (r=0.753, P<0.05). The results of this study provide the first evidence that increased expression of TIM-1 in asthmatic mice is associated with the Th2-associated transcription factor GATA-3. The findings suggest a possible mechanism for how HAV infection and TIM-1 upregulation influence the development of allergic asthma.

Roles of galectin-9 in the development of experimental allergic conjunctivitis in mice

BACKGROUND

Galectin-9 was recently identified as a ligand for Tim-3, which negatively regulates Th1 cells. Here, we investigated whether administration of anti-galectin-9 antibodies (Abs) affects the development of murine experimental allergic conjunctivitis (EC), a Th2-mediated disease.

METHODS

EC was induced in BALB/c mice by active immunization with ragweed (RW) followed by RW challenge in eye drops. Normal rat IgG (nrIgG) or anti-galectin-9 Ab was injected intraperitoneally into the mice either during the induction phase treatment or effector phase treatment. Alternatively, Abs were injected into the subconjunctival space during the effector phase. To evaluate in vitro effects of anti-galectin-9 Abs, splenocytes from RW-sensitized mice were cultured in vitro with RW in the presence of nrIgG or anti-galectin-9 Abs. To induce EC, these splenocytes were transferred into naïve BALB/c mice followed by RW challenge.

RESULTS

Treatment with anti-galectin-9 Abs in vivo during either the induction or effector phase did not significantly affect the severity of EC. However, when the splenocytes from RW-primed mice treated with anti-galectin-9 Abs during the induction phase were stimulated in vitro and adoptively transferred into naïve recipients, they induced significantly severer EC. In contrast, when RW-primed splenocytes were restimulated in vitro with RW in the presence of anti-galectin-9 Abs and then adoptively transferred, they induced less severe EC and produced significantly less IL-5 and IL-13 and more IFN-gamma compared to nrIgG-treated control splenocytes.

CONCLUSIONS

These observations may reflect the fact that galectin-9 not only regulates T-cell function, it is also involved in many other biological functions.

TIM-4 expressed by mucosal dendritic cells plays a critical role in food antigen-specific Th2 differentiation and intestinal allergy

BACKGROUND & AIMS

Food allergy accounts for significant morbidity. The etiology and immune mechanisms of food allergy, however, have remained poorly understood. In this study, we aimed to determine the role of T-cell immunoglobulin-domain and mucin-domain (TIM)-4, a recently identified member of cell surface molecules, in the pathogenesis of intestinal allergy in a murine model.

METHODS

We report that TIM-4 as well as costimulatory molecules were up-regulated in intestinal mucosal dendritic cells by in vitro or in vivo exposure to Staphylococcus enterotoxin B (SEB). SEB-conditioned intestinal dendritic cells loaded with a food macromolecule ovalbumin (OVA) induced potent OVA-specific T-helper (Th)2 lymphocyte responses in vitro and such Th2 responses were inhibited completely by TIM-4 blockade.

RESULTS

In vivo exposure to both SEB and OVA resulted in OVA-specific Th2 differentiation and intestinal allergic responses including increased serum immunoglobulin E and Th2 cytokine levels, activation of OVA-specific Th2 cells detected both ex vivo and in situ, and mast cell degranulation. Of importance, in vivo abrogation of TIM-4 or its cognate ligand TIM-1 by using a polyclonal antibody remarkably dampened Th2 differentiation and intestinal allergy.

CONCLUSIONS

Our study thus identifies TIM-4 as a novel molecule critically required for the development of intestinal allergy.

TIM-1 and TIM-3 enhancement of Th2 cytokine production by mast cells

Members of the T-cell immunoglobulin- and mucin-domain-containing molecule (TIM) family have roles in T-cell-mediated immune responses. TIM-1 and TIM-2 are predominantly expressed on T helper type 2 (Th2) cells, whereas TIM-3 is preferentially expressed on Th1 and Th17 cells. We found that TIM-1 and TIM-3, but neither TIM-2 nor TIM-4, were constitutively expressed on mouse peritoneal mast cells and bone marrow-derived cultured mast cells (BMCMCs). After IgE + Ag stimulation, TIM-1 expression was down-regulated on BMCMCs, whereas TIM-3 expression was up-regulated. We also found that recombinant mouse TIM-4 (rmTIM-4), which is a ligand for TIM-1, as well as an anti-TIM-3 polyclonal Ab, can promote interleukin-4 (IL-4), IL-6, and IL-13 production without enhancing degranulation in BMCMCs stimulated with IgE + Ag. Moreover, the anti-TIM-3 Ab, but neither anti-TIM-1 Ab nor rmTIM-4, suppressed mast-cell apoptosis. These observations suggest that TIM-1 and TIM-3 may be able to influence T-cell-mediated immune responses in part through effects on mast cells.

Inverse association between T-cell immunoglobulin and mucin domain-1 and T-bet in a mouse model of allergic rhinitis

BACKGROUND

It has been suggested that human hepatitis A virus cellular receptor, also known as T-cell immunoglobulin and mucin domain-1 (TIM-1), plays an important role in the development of allergic diseases on the basis of epidemiologic data, but the molecular mechanism has been unclear. In a murine model of ovalbumin (OVA)-sensitized allergic rhinitis (AR), we examined the expression of TIM-1 and its correlation with T helper1-associated transcription factor, T-bet, as a potential mediator of T-cell immunoglobulin expression.

METHODS

Mice were challenged intranasally with OVA to elicit AR. The expression of TIM-1 in nasal tissues was examined by real-time reverse-transcription polymerase chain reaction (RT-PCR), and the surface expression of TIM-1 in peripheral blood mononuclear cells was evaluated by means of flow cytometry. In addition, the expression of TIM-1 as well as T-bet in splenic lymphocytes was examined by Western blotting.

RESULTS

TIM-1 mRNA was increased significantly in nasal tissues (P < .05) as seen by real-time RT-PCR. Flow cytometry indicated a differential TIM-1 expression of 135.5 +/- 34.2 in the AR group versus 51.1 +/- 10.9 in the control group (P < .05). The mean values of normalized TIM-1 were 0.43 +/- 0.18 and 0.21 +/- 0.10 in AR and control groups, respectively, whereas the mean values of normalized T-bet were 0.22 +/- 0.13 and 0.67 +/- 0.17 in the AR and control groups, respectively. There was a significant difference in the production of TIM-1 as well as T-bet in AR mice versus control mice (P < .05). The increased production of TIM-1 correlated significantly with the decreased T-bet in spleen tissue of AR mice (r = -0.52, P < .05).

CONCLUSION

Our experimental model recapitulates an increase in lymphocyte TIM-1 expression seen in AR both locally and systemically. Our results also demonstrate an inverse relationship between lymphocyte TIM-1 and T-bet expression, suggesting a possible mechanism that TIM-1 influences the development of AR.

Human TIM-1 associates with the TCR complex and up-regulates T cell activation signals

The T cell, Ig domain, and mucin domain-1 (TIM-1) gene is associated with Th2 T cell responses and human atopic diseases. The mechanism by which TIM-1 influences T cell responses remains unknown. We demonstrate that TIM-1 is recruited to the TCR-signaling complex via association with CD3. TIM-1 up-regulates TCR-associated signaling events, including phosphorylation of Zap70 and IL-2-inducible T cell kinase. This activity requires TIM-1 tyrosine phosphorylation. TIM-1 expression induces formation of a novel complex that includes PI3K and ITK. Finally, the consequences of TIM-1 activation include increased expression of effector cytokines. These results demonstrate that TIM-1 is a critical component of the human T cell response and provide a mechanistic hypothesis for the role of TIM-1 in disease.

Immune regulation by the TIM gene family

Recent studies have demonstrated that proteins of the T cell immunoglobulin and mucin domain (TIM) family are important regulators of immune function. Here we discuss the functional effects of TIM proteins on immune responses, how the effects of TIM proteins may be modulated by interactions with ligands and the limited information available on intracellular signals downstream of TIM proteins.

Staphylococcal enterotoxin B increases TIM4 expression in human dendritic cells that drives naïve CD4 T cells to differentiate into Th2 cells

Aberrant T helper (Th)2 polarization plays a critical role in the pathogenesis of allergic disorders; the etiology remains unclear. Dendritic cells (DCs) express T cell immunoglobulin mucin domain (TIM)4 that ligates TIM1 on CD4 T cells to drive them to become Th2 cells, but the pathogenic source of TIM4 is unknown. Here we report that a significant increase in TIM4 expression in human DCs was observed in response to Staphylococcal enterotoxin B (SEB) stimulation via Toll-like receptor (TLR)2 and nucleotide-binding oligomerization domain (NOD)1 pathway. Coculture SEB-conditioned DCs with naïve CD4 T cells induced Th2 responses that could be abolished using TLR2 or NOD1 or TIM4 or TIM1 with counterpart antibodies or RNA interference. The results demonstrate that Staphylococcus aureus derived SEB promotes the TIM4 production in human DCs. The interaction between TIM4 and TIM1 drives naïve CD4 T cells to develop to Th2 cells.

Epitope-dependent effect of anti-murine TIM-1 monoclonal antibodies on T cell activity and lung immune responses

The TAPR locus containing the TIM gene family is implicated in the development of atopic inflammation in mouse, and TIM-1 allelic variation has been associated with the incidence of atopy in human patient populations. In this study, we show that manipulation of the TIM-1 pathway influences airway inflammation and pathology. Anti-TIM-1 mAbs recognizing distinct epitopes differentially modulated OVA-induced lung inflammation in the mouse. The epitopes recognized by these Abs were mapped, revealing that mAbs to both the IgV and stalk domains of TIM-1 have therapeutic activity. Unexpectedly, mAbs recognizing unique epitopes spanning exon 4 of the mucin/stalk domains exacerbated immune responses. Using Ag recall response studies, we demonstrate that the TIM-1 pathway acts primarily by modulating the production of T(H)2 cytokines. Furthermore, ex vivo cellular experiments indicate that TIM-1 activity controls CD4(+) T cell activity. These studies validate the genetic hypothesis that the TIM-1 locus is linked to the development of atopic disease and suggest novel therapeutic strategies for targeting asthma and other atopic disorders.

Cutting edge: inhibition of T cell activation by TIM-2

T cell Ig and mucin domain protein 2 (TIM-2) has been shown to regulate T cell activation in vitro and T cell-mediated disease in vivo. However, it is still not clear whether TIM-2 acts mainly to augment T cell function or to inhibit it. We have directly examined the function of TIM-2 in murine and human T cell lines. Our results indicate that expression of TIM-2 significantly impairs the induction of NFAT and AP-1 transcriptional reporters by not only TCR ligation but also by the pharmacological stimuli PMA and ionomycin. This does not appear to be due to a general effect on cell viability, and the block in NFAT activation can be bypassed by expression of activated alleles of Ras or calcineurin, or MEK kinase, in the case of AP-1. Thus, our data are consistent with a model whereby TIM-2 inhibits T cell activation.

Antibodies to T-cell Ig and mucin domain-containing proteins (Tim)-1 and -3 suppress the induction and progression of murine allergic conjunctivitis

The T cell Ig and mucin domain-containing proteins (Tim) regulate Th1- and Th2-mediated immune responses. We investigated the ability of Abs blocking Tim-1 or Tim-3 ligand-binding activity to prevent and treat murine experimental allergic conjunctivitis (EC), a Th2-mediated disease. Treatment with either Ab during the induction phase of EC in actively immunized wild-type mice suppressed EC and upregulated Th1 and Th2 immune responses. In contrast, both Abs exacerbated EC in actively immunized IFN-gamma-knockout mice. Thus, both anti-Tim Abs suppress the pathogenic immune responses generated in the induction phase by upregulating systemic IFN-gamma production. Treatment of actively immunized mice and passively immunized mice with either anti-Tim Ab just prior to RW challenge also suppressed EC. Thus, treatment with anti-Tim-1 or anti-Tim-3 Ab can suppress both the induction and progression of EC, which could indicate potential preventive and/or therapeutic approaches for allergic diseases such as allergic conjunctivitis.

T cell, Ig domain, mucin domain-2 gene-deficient mice reveal a novel mechanism for the regulation of Th2 immune responses and airway inflammation

The development of asthma and other atopic diseases is influenced by cytokines produced by Th2 effector T cells. How effector T cell responses are regulated once these cell populations are established remains unclear. The recently described T cell and airway phenotype regulator locus, containing the T cell, Ig domain, mucin domain (TIM) genes, is genetically associated with Th2 cytokine production and Th2-dependent immune responses. In this study, we report the phenotype of the TIM-2 gene-deficient mouse, and demonstrate exacerbated lung inflammation in an airway atopic response model. Immune responses in the TIM-2-deficient mouse reveal disregulated expression of Th2 cytokines, and adoptive transfer experiments show that the T cell compartment is responsible for the heightened inflammatory phenotype. These studies show that TIM-2 is a novel and critical regulator of effector T cell activity.

Attenuated Salmonella typhimurium reduces ovalbumin-induced airway inflammation and T-helper type 2 responses in mice

Cytokines produced by Th2 cells are responsible for the pathogenesis of asthma. Th1-biased immune responses caused by attenuated salmonella have the potential to relieve asthmatic symptoms. We evaluated whether oral administration of attenuated salmonella could modulate allergic responses in a chicken ovalbumin (OVA)-induced asthmatic murine model. Mice were fed with attenuated salmonella SL7207 one dose before and three doses during the induction of an allergic response. Lung histology, percentages of eosinophil in bronchoalveolar lavage fluid, serum levels of OVA-specific antibodies and cytokine production by OVA-activated splenocytes were evaluated in mice with or without the administration of SL7207. A significant reduction in pulmonary eosinophilic infiltration was observed in mice receiving attenuated salmonella. Lower levels of OVA-specific IgG1 but higher titres of OVA-IgG2a in serum were also detected in this group. Splenocytes from salmonella-fed mice produced lower levels of Th2 cytokines upon OVA stimulation. The administration of attenuated salmonella significantly suppressed immunopathological symptoms in OVA-sensitized mice. Inhibition of Th2 responses might explain the potential mechanisms. This study provides some evidence for the feasibility of attenuated salmonella as an effective vaccine for allergic diseases.

Strategies for targeting T-cells in allergic diseases and asthma

T helper (Th) 2 lymphocytes play a crucial role in the initiation, progression and persistence of allergic diseases, including asthma. Drugs that interfere with the activation of T-cells or more selectively Th2-specific signaling molecules and drugs that prevent the selective migration into lung tissue are promising novel strategies for the treatment of allergic asthma. Although the mainstay asthma therapy of inhaled glucocorticoids is rather effective, targeting Th2 cells may be an important alternative in childhood. Regulatory T-cells (Treg cells) have a physiological role in protection of unwanted immune responses to auto-antigens and allergens. Literature data indicate that an imbalance between Th2 and Treg cells may underlie development and disease expression of allergic asthma. Drugs or immunotherapies that stimulate these counter-Treg cells may limit aberrant Th2 responses leading to suppression of symptoms. Furthermore, these types of treatments may offer the perspective of disease modification and long-term relief of symptoms.