Increased expression of human T-cell immunoglobulin- and mucin-domain-containing molecule-4 in peripheral blood mononuclear cells from patients with system lupus erythematosus

V-Set Immunoglobulin Domain-Containing Protein 4 as a Novel Serum Biomarker of Lupus Nephritis and Renal Pathology Activity

OBJECTIVE

To discover novel serum biomarkers that have diagnostic or predictive value in lupus nephritis (LN).

METHODS

Using a quantitative protein microarray, we screened for high-abundant proteome expression in the serum of patients with LN compared to healthy controls. Top candidates from this screening were validated using a larger cohort of patients with LN compared to a disease control cohort (subjects with other chronic kidney diseases) and a healthy control cohort. Promising markers were then selected using a machine-learning model and further validated with a larger patient cohort. The corresponding autoantibodies and immune complexes containing these proteins were also examined.

RESULTS

In total, 13 proteins were found to be significantly elevated in LN patient serum in the screening, among which 8 proteins were validated by enzyme-linked immunosorbent assay using 81 serum samples from LN patients and control subjects. Three serum markers with LN diagnostic potential were identified using feature importance analysis and further validated using 155 serum samples from LN patients and control subjects. V-set immunoglobulin domain-containing protein 4 (VSIG4) appeared to be the most promising marker in distinguishing LN from healthy controls, with an area under the curve of 0.93. VSIG4 could also discriminate active LN from inactive LN. Furthermore, serum VSIG4 levels were positively correlated with all of the following clinical parameters: the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score (Spearman's rank correlation rs = 0.42, P < 0.001), the renal domain score of the SLEDAI (rs = 0.46, P < 0.001), the urinary protein-to-creatinine ratio (rs = 0.56, P < 0.001), and the serum creatinine level (rs = 0.41, P < 0.001). Importantly, we found that serum VSIG4 levels tracked with LN disease activity longitudinally, and that serum VSIG4 levels reflected the renal pathology activity index (AI), particularly the AI components of crescent formation and hyaline deposits.

CONCLUSION

VSIG4 may be a promising novel serum biomarker and therapeutic target in patients with LN.

HPV and molecular mimicry in systemic lupus erythematosus and an impact of compiling B-cell epitopes and MHC-class II binding profiles with in silico evidence

Epidemiological link between HPV and SLE is evolving. The possibility of HPV infection-induced molecular mimicry and systemic lupus erythematosus (SLE) was elucidated through detailed in silico analyses. Conserved regions in the structural protein sequences of high-risk HPV types were inferred, and sequence homologies between viral and human peptides were identified to delineate proteins implicated in SLE. B-cell epitopes and MHC-class II binding were compiled using Immune Epitope Database and ProPred II analysis tool. Molecular modeling and molecular dynamics/simulation (MDS) were performed using AutoDock Vina and GROMACS, respectively. Sequence alignment revealed 32 conserved regions, and 27/32 viral peptides showed varying similarities to human peptides, rich in B-cell epitopes with superior accessibility, high hydrophilicity, antigenicity and disposition to bind many class-II HLA alleles. Molecular docking of 13 viral peptides homologous (100%) to human peptides implicated in SLE showed that VIR-PEP1 (QLFNKPYWL) and VIR-PEP2 (DTYRFVTS) exhibited higher binding affinities than corresponding human peptides to SLE predisposing HLA-DRB1 allele. MDS of these peptides showed that the viral peptides had superior folding, compactness, and a higher number of hydrogen bonds than human peptides throughout the simulation period. SASA analysis revealed that the VIR-PEP1&2 fluctuated less frequently than corresponding human peptides. MM-PBSA revealed that the VIR-PEP2 complex exhibited higher binding energy than the human peptide complex. This suggests that highly conserved structural peptides of high-risk HPV types homologous to human peptides could compete and bind avidly to the HLA allele associated with SLE and predispose HPV-infected individuals to SLE through molecular mimicry.Communicated by Ramaswamy H. Sarma.

Function and characteristics of TIM‑4 in immune regulation and disease (Review)

T‑cell/transmembrane immunoglobulin and mucin domain containing 4 (TIM‑4) is a phosphatidylserine receptor that is mainly expressed on antigen‑presenting cells and is involved in the recognition and efferocytosis of apoptotic cells. TIM‑4 has been found to be expressed in immune cells such as natural killer T, B and mast cells and to participate in multiple aspects of immune regulation, suggesting that TIM‑4 may be involved in a variety of immune‑related diseases. Recent studies have confirmed that TIM‑4 is also abnormally expressed in a variety of malignant tumor cells and is closely associated with the occurrence and development of tumors and the tumor immune microenvironment. The present study aimed to describe the expression and functional characteristics of TIM‑4 in detail and to comprehensively discuss its role in pathophysiological processes such as infection, allergy, metabolism, autoimmunity and tumor immunity. The current review provided a comprehensive understanding of the functions and characteristics of TIM‑4, as well as novel ideas for the diagnosis and treatment of diseases.

Novel Roles of the Tim Family in Immune Regulation and Autoimmune Diseases

T cell Ig and mucin domain (Tim) protein family members were identified to be important regulators of the immune response. As their name indicates, Tim proteins were originally considered a T cell-specific markers, and they mainly regulate the responses of T helper cells. However, accumulating evidence indicates that Tims are also expressed on antigen-presenting cells (APCs), such as monocytes, macrophages, dendritic cells (DCs) and B cells, and even plays various roles in natural killer cells (NKs) and mast cells. In recent years, the expression and function of Tims on different cells and the identification of new ligands for the Tim family have suggested that the Tim family plays a crucial role in immune regulation. In addition, the relationship between Tim family gene polymorphisms and susceptibility to several autoimmune diseases has expanded our knowledge of the role of Tim proteins in immune regulation. In this review, we discuss how the Tim family affects immunomodulatory function and the potential role of the Tim family in typical autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and type 1 diabetes (T1D). A deeper understanding of the immunoregulatory mechanism of the Tim family might provide new insights into the clinical diagnosis and treatment of autoimmune diseases.

Correlations Between TIMD-4 Gene Variants and the Risk and Clinical Features of Rheumatoid Arthritis in a Chinese Population

Introduction

T-cell immunoglobulin and mucin domain-4 (TIMD-4) are likely to impact autoimmune diseases (e.g., rheumatoid arthritis (RA)). It is hypothesized here that TIMD-4 gene polymorphism is likely to display a correlation with the RA risk.

Methods

For examining the effect exerted by TIMD-4 genetic variant in the RA risk, a case–control study containing 379 RA cases and 432 healthy control groups in Chinese population was performed. This study conducted genotyping with the use of a custom-by-design 48-Plex single nucleotide polymorphism (SNP) Scan™ Kit. Blood serum conditions of TIMD-4 in RA cases and matched control groups were measured by enzyme-connected immunosorbent assay (ELISA).

Results

Our results demonstrated that the TIMD-4 rs7700944 polymorphism could increase the RA risk in Chinese population. According to stratification analyzing processes, the TIMD-4 rs7700944 polymorphism displayed the correlation to the elevated RA risk in the females, smokers and cases aged ≥55 years. Cross-over analyses also indicated that the combined effect of smoking or drinking and GA genotype of rs7700944 locus contributed to an elevated risk of RA. In addition, the TIMD-4 rs7700944 polymorphism was also related to RA cases with DAS ≥ 3.20, ESR ≥25.00 mm/h and positive anti-ccp. Moreover, compared with the control groups, the average expression level of TIMD-4 in the serum of RA cases was apparently increased.

Conclusion

In conclusion, the TIMD-4 rs7700944 polymorphism may increase the sensitivity to RA in Chinese population.

Tim-4 expressing monocytes as a novel indicator to assess disease activity and severity of ulcerative colitis

AIMS

The dysregulation of the immune response has been shown to be involved in ulcerative colitis (UC) pathogenesis. Tim-4 is a potential regulator of the immune system which plays key roles in multiple autoimmune diseases. However, whether it is involved in UC remains unclear. The aim of this research was to determine the expression of Tim-4 on circulating monocytes and its clinical significance in UC patients.

MAIN METHODS

In total, 36 UC patients and 34 healthy controls (HCs) were enrolled in this study. The frequencies of CD14⁺Tim-4⁺ cells, regulatory T cells (Treg) and CD14⁺HLA-DR^-/low myeloid-derived suppressor cells (MDSCs) in the peripheral blood were determined by flow cytometry. Serum IL-6 levels were determined by chemiluminescence immunoassay.

KEY FINDINGS

The percentage of CD14⁺Tim-4⁺ cells was higher in UC patients than in HCs. The frequency of Treg cells was significantly decreased, while that of MDSCs was significantly increased in UC patients. The frequency of CD14⁺Tim-4⁺ cells was significantly elevated in subjects with high severity, high number of defecations per day, high UC disease activity index Mayo score, high IgG, and high levels of inflammatory markers. And the percentages of Tim-4-expressing monocytes were significantly decreased in UC patients that received a 3-week treatment with mesalazine. Furthermore, the frequency of CD14⁺Tim-4⁺ cells was also positively correlated with MDSCs and negatively correlated with Treg cells.

SIGNIFICANCE

CD14⁺Tim-4⁺ cells was elevated in UC patients and could be a novel indicator to assess disease severity and activity of UC.

Tim-4 in Health and Disease: Friend or Foe?

T-cell immunoglobulin and mucin domain containing 4 (Tim-4) is a phosphatidylserine receptor and is selectively expressed on antigen presenting cells. Recently, Tim-4 was reported to be expressed on iNKT cells, B1 cells, and tumor cells, suggesting it has multiple biological functions. In this review, we mainly summarize the expression and regulation of Tim-4 in immune cells including T cells, macrophages, dendritic cells, NKT cells, B cells, and mast cells. The expression of Tim-4 in these cells implies that Tim-4 might participate in immune related diseases. Emerging evidence emphasizes a substantial role for Tim-4 in maintaining homeostasis by regulating various immune responses, including viral infection, allergy, autoimmunity, and tumor immunity. Here, we collectively evaluated the role of Tim-4 in health and diseases. This summary will be extremely useful to fully understand the function of Tim-4 in the pathogenesis of immune related diseases, which would provide novel clues for the diagnosis and treatment of diseases.

Association of Tim-4 expression in monocyte subtypes with clinical course and prognosis in acute ischemic stroke patients

Background: It has been proven that T cell immunoglobin and mucin domain (Tim)-4 and monocytes (Mo) are involved in regulation of immunity, which is important for the recovery of acute ischemic stroke (AIS).Methods: In this study, the expression of Tim-4 in both circulating Mo subtypes and plasma in 32 consecutive AIS patients and 32 control patients was assessed to determine their correlation with the clinical course and prognosis of AIS.Results: It was found that, compared to the control patients, the percentage of Tim-4 expression in overall Mo, classical Mo and non-classical Mo was significantly elevated after 2 and 5 days of stroke (p < 0.05), while it was promoted from 0 to 10 days of stoke in intermediate Mo (p < 0.05). Furthermore, Tim-4 expressions in non-classical Mo and intermediate Mo were obviously correlated with National Institutes of Health Stroke Scale (NIHSS) scores at 2 days of stroke (r = 0.351, p = 0.048; r = 0.358, p = 0.044, respectively). In poor outcome (PO) patients, the expression of Tim-4 in non-classical Mo was remarkably promoted at 2 days of stroke in comparison with non-PO patients (p < 0.05). More importantly, our results revealed a positive correlation between Tim-4 expression in non-classical Mo and interleukin (IL)-6 plasma levels in AIS patients without infection.Conclusion: In summary, our findings proved that Tim-4 expression in non-classical Mo could be an appropriate target for the prediction of the clinical course and prognosis in AIS patients.

Value of combined detection of anti-nuclear antibody, anti-double-stranded DNA antibody and C3, C4 complements in the clinical diagnosis of systemic lupus erythematosus

Combined detection of antinuclear antibody (ANA), anti-double-stranded DNA (ds-DNA) antibody and complements C3 and C4 in the diagnosis of systemic lupus erythematosus (SLE) was analyzed. One hundred and ninety-four patients with SLE admitted to Yantaishan Hospital of Yantai from January 2012 to December 2017 were selected as SLE group. A total of 106 patients with non-SLE rheumatic disease were selected as disease control group and 120 healthy subjects as healthy control group. The ANA and anti-ds-DNA antibodies were detected by ELISA and complement C3 and C4 were detected by rate nephelometry. The sensitivity and specificity of these four factors were also analyzed for the diagnosis of SLE. The sensitivity and specificity of ANA in diagnosing SLE were 91.75 and 79.65%, respectively; of anti-ds-DNA antibody were 67.01 and 98.23%, respectively; of complement C3 were 87.11 and 82.74%, respectively; and of complement C4 were 88.66 and 77.43%, respectively. The sensitivity and specificity of ANA and anti-ds-DNA antibody in the diagnosis of SLE were 95.36 and 96.90%, respectively; of C3 and C4 were 92.78 and 79.20%, respectively; and the sensitivity and specificity of the combination of all four indicators were 97.42 and 80.97%, respectively. The combined diagnosis of SLE with ANA, anti-ds-DNA antibody, complement C3 and C4 can play a complementary role in the diagnosis and treatment of SLE patients, and it is of great significance to the diagnosis and treatment planning of SLE patients.

Diverse roles of TIM4 in immune activation: implications for alloimmunity

PURPOSE OF REVIEW

T-cell immunoglobulin and mucin domain-containing molecule (TIM)4 is a costimulatory molecule and phosphatidylserine receptor. Its dominant function varies according to the expressing cell and site of activation. In recent years, studies have identified its role in diverse disease processes and increasingly in alloimmunity. Herein, we will comprehensively review the literature on TIM4 and outline its function in shaping the alloimmune response.

RECENT FINDINGS

TIM4 expression on dendritic cells increases following transplantation. Blockade of TIM4 in vivo leads to increased differentiation of regulatory T cells and improved allograft survival. TIM4 binds phosphatidylserine-expressing apoptotic cells. Previously thought of as a tethering molecule, recent studies have demonstrated that TIM4 interacts with integrins to mediate uptake of apoptotic cells. TIM4 B cells have recently been identified, which produce high levels of IFNγ and promote allograft rejection. Targeting these B cells improved allograft survival and promoted the development of TIM1 regulatory B cells.

SUMMARY

TIM4 is expressed in niche compartments and has many immunological effects. However, inhibition of TIM4 has been demonstrated to prolong allograft survival, through varied mechanisms. A unifying explanation for the role of TIM4 in alloimmunity remains to be found, but this pathway appears to hold considerable promise in transplantation.

Promoter polymorphisms of the TIM-4 gene are correlated with disease activity in patients with systemic lupus erythematosus

Although the TIM gene family plays important roles in immune responses, little is known about TIM regulation in the development of systemic lupus erythematosus (SLE). This study aimed to investigate the association of two TIM-4 single nucleotide polymorphisms (SNPs) rs6874202 (-1419G>A) and rs62382402 (-1609G>A) with SLE susceptibility in a Chinese Han population. The results showed no significant differences between patients with SLE and control group for rs6874202 and rs62382402 (p = .72, .53 respectively). However, the anti-dsDNA levels in serum from SLE patients with GG genotype of TIM-4 gene at -1419 site were significantly higher than those with GA and AA genotype (p = .0335), and C3 levels of SLE patients with GG and GA genotype were much lower than those with AA genotypes (p = .0187). Moreover, the apoptotic cell levels of SLE patients with AA and GG genotypes were significantly higher than those with GA genotypes in patients with SLE (p = .0393). In addition, the C3 concentration of SLE patients with the GG genotype of TIM-4 gene at -1609 site was found to be significantly higher than those with the GA genotype (p = .0129). The results imply that GG genotype of the TIM-4 gene at -1419 site might be associated with the disease activity of SLE.

Tim-4 protects mice against lipopolysaccharide-induced endotoxic shock by suppressing the NF-κB signaling pathway

Endotoxic shock is the primary cause of morbidity and mortality in hospital patients, creating an urgent need to explore the mechanisms involved in sepsis. Our previous studies showed that T-cell immunoglobulin- and mucin-domain-containing molecule-4 (Tim-4) attenuated the inflammatory response through regulating the functions of macrophages. However, the mechanism by which Tim-4 does this has not been fully elucidated. In this study, we found that Tim-4 expression was increased in lipopolysaccharide (LPS)-induced endotoxic shock. Interestingly, the survival rate of mice in the Tim-4 overexpression group was higher than that of the control group after LPS administration. To investigate the function of Tim-4 in LPS-induced inflammation, we further demonstrated that Tim-4 attenuated LPS-induced endotoxic shock by inhibiting cytokine production by macrophages. Blocking expression of Tim-4 and nuclear factor-kappa B (NF-κB) signal inhibition showed that Tim-4 inhibited cytokine production via NF-κB signaling pathway. This study indicates that Tim-4 may exert its immune modulation by regulating inflammatory factor secretion and might act as a novel potential target for inflammatory diseases, especially endotoxic shock.

Increased T cell immunoglobulin and mucin domain containing 4 (TIM-4) is negatively correlated with serum concentrations of interleukin-1β in type 2 diabetes

BACKGROUND

T cell immunoglobulin and mucin domain containing 4 (TIM-4), a novel immune regulator, is selectively expressed on antigen-presenting cells, especially macrophages and mature dendritic cells. Although TIM-4 plays key roles in mutiple immune diseases, whether it is involved in type 2 diabetes mellitus (T2D) remains unknown. The aim of the present study was to investigate the expression of TIM-4 in T2D and determine its significance in disease progression.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from T2D patients and healthy controls to measure TIM-4 mRNA expression by real-time polymerase chain reaction (PCR), and sera were collected to determine interleukin (IL)-1β concentrations and other clinical indicators (high-sensitivity C-reactive protein [hsCRP], total cholesterol, low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol, triglyceride, fasting glucose, HbA1c, aspartate aminotransferase, and alanine aminotransferase).

RESULTS

Expression of TIM-4 mRNA was increased significantly in PBMCs from T2D patients compared with healthy controls. There was a positive correlation between TIM-4 mRNA expression and serum concentrations of hsCRP. However, there was a negative correlation between TIM-4 mRNA expression and IL-1β concentrations, indicating the potential role for TIM-4 to negatively regulate IL-1β production. In addition, TIM-4 mRNA expression was negatively correlated with lowLDL-C, and there was a tendency for a negative relationship between TIM-4 mRNA expression and HbA1c.

CONCLUSIONS

The results of the present study indicate that TIM-4 contributes, at least in part, to the pathogenesis of T2D, possibly by regulating IL-1β.

TIM-4 promotes the growth of non-small-cell lung cancer in a RGD motif-dependent manner

BACKGROUND

T-cell immunoglobulin domain and mucin domain 4 (TIM-4) is exclusively expressed in antigen-presenting cells and involved in immune regulation. However, the role of TIM-4 expressed in tumour cells remains completely unknown.

METHODS

Immunohistochemistry staining was used to examine TIM-4 or Ki-67 expression in tumour tissues. Real-time PCR or RT-PCR was performed to detect TIM-4 mRNA expression. Lung cancer cell growth and proliferation were conducted by CCK-8 assay and EdU staining. Cell cycle progression was analysed by flow cytometry. The PCNA and cell cycle-related proteins were verified by western blot. Co-IP assay was used to identify the interaction of TIM-4 and integrin αvβ3. The efficacy of TIM-4 in vivo was evaluated using xenograft tumour model.

RESULTS

The expression of TIM-4 in non-small-cell lung cancer (NSCLC) tissues was significantly higher than that of the adjacent tissues. Enhanced TIM-4 expression was negatively correlated with histological differentiation of lung carcinoma and lifespan of patients. Overexpression of TIM-4 promoted lung cancer cell growth and proliferation, and upregulated the expression of PCNA, cyclin A, cyclin B1 and cyclin D1, accompanied by accumulation of lung cancer cells in S phase. Interestingly, Arg-Gly-Asp (RGD) motif mutation abolished the effect of TIM-4 on lung cancer cells, which was further verified by tumour xenografts in mice. Furthermore, we found that TIM-4 interacted with αvβ3 integrin through RGD motif.

CONCLUSIONS

This finding suggests that TIM-4 might be a potential biomarker for NSCLC that promotes lung cancer progression by RGD motif.

Tim-4 Inhibits NO Generation by Murine Macrophages

Objective

T cell immunoglobulin- and mucin-domain-containing molecule-4 (Tim-4) receives much attention as a potentially negative regulator of immune responses. However, its modulation on macrophages has not been fully elucidated so far. This study aimed to identify the role of Tim-4 in nitric oxide (NO) modulation.

Methods

Macrophages were stimulated with 100 ng/ml LPS or 100 U/ml IFN-γ. RT-PCR was performed to detect TIM-4 mRNA expression. Tim-4 blocking antibody and NF-κB inhibitory ligand were involved in the study. NO levels were assayed by Griess reaction. Phosphorylation of NF-κB, Jak2 or Stat1 was verified by western blot.

Results

Tim-4 was up-regulated in murine macrophages after interferon-gamma (IFN-γ) stimulation. Tim-4 over-expression decreased NO production and inducible nitric oxide synthase (iNOS) expression in lipopolysaccharide (LPS) or IFN-γ-stimulated macrophages. Consistently, Tim-4 blockade promoted LPS or IFN-γ-induced NO secretion and iNOS expression. Tim-4 over-expression decreased LPS-induced nuclear factor kappa B (NF-κB) p65 phosphorylation in macrophages, which was abrogated by NF-κB inhibitory ligand. On the contrary, Tim-4 blocking increased LPS-induced NF-κB signaling, which was also abrogated by NF-κB inhibition. In addition, Tim-4 blockade promoted Jak2 and Stat1 phosphorylation in IFN-γ stimulated macrophages.

Conclusion

These results indicate that Tim-4 is involved in negative regulation of NO production in macrophages, suggesting the critical role of Tim-4 in immune related diseases.

Incomplete clearance of apoptotic cells in systemic lupus erythematosus: pathogenic role and potential biomarker

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with repeated inflammation against multiple organs. Although its pathophysiology is not yet unveiled, uncleared apoptotic cells and their accumulation in tissue contribute to the autoimmune disturbance in SLE. Apoptosis is a programmed cell death process, which maintains tissue homeostasis and inhibits the development of any further immune response against apoptotic remnants. Earlier studies revealed that various 'eat-me' signals on apoptotic cells, bridging molecules and their receptors on phagocytes play a role in such a complicated process. Tyro3-Axl-Mer receptors, their bridging molecules, milk fat globulin epidermal growth factor-8, T-cell immunoglobulin mucin domain protein family, scavenger receptors, C1q, and pentraxins were found to be abnormal in SLE. In this review, apoptosis and clearance of its remnants are summarized, and the molecules involved in the incomplete clearance of apoptotic cells in SLE are discussed.

Significance of K(L/V)WX(I/L/V)P Epitope of the B2Gpi in Its (Patho)Physiologic Function

β2-glycoprotein I (β2GPI) is a major autoantigen of autoimmune thrombophilia, known as the antiphospholipid syndrome. The exact mechanism underlying the β2GPI's involvement in the disease is not fully elucidated, as it is not its physiological role. We used random phage peptide library to identify sequences binding to β2GPI. Obtained K(L/V)WX(I/L/V)P motif, primarily designated as target unrelated, was confirmed as the selective binder of β2GPI. Based on this motif we confirmed the previously suggested role of polar residues in β2GPI interactions, and identified some already known and some new putative β2GPI binding proteins. The latter can help to further elucidate β2GPI's (patho)physiological role.

Glioma-derived T cell immunoglobulin- and mucin domain-containing molecule-4 (TIM4) contributes to tumor tolerance

Tumor tolerance plays a critical role in tumor growth and escape from immune surveillance. The mechanism of tumor tolerance development is not fully understood. Regulatory T cells (Tregs) play a critical role in tumor tolerance. TIM4 (T cell immunoglobulin- and mucin domain-containing molecule-4) is involved in immune regulation. We investigated the role of TIM4 in the induction of Tregs in tumors. Surgically removed glioma tissue and peripheral blood samples were obtained from 25 glioma patients. Immune cells were isolated from the tissue and blood samples. Confocal microscopy was employed to detect macrophages phagocytosing apoptotic T cells. The generation of tumor-specific Tregs and the immune suppression function of Tregs were observed in cell culture models. High levels of TIM4 were detected in glioma-derived macrophages. Phosphatidylserine (PS) was detected in glioma-derived T cells; naïve T cells expressed low levels of PS that could be up-regulated by hypoxia. Glioma-derived macrophages phagocytosed PS-expressing T cells, gaining the tolerogenic properties, which could induce tumor-specific Tregs; the latter could suppress tumor-specific CD8(+) T cells. We conclude that macrophage-derived TIM4 plays an important role in the induction of Tregs in gliomas, which may play an important role in tumor tolerance.