Tim-3: an activation marker and activation limiter of innate immune cells

Advances in immunotherapy for breast cancer and feline mammary carcinoma: From molecular basis to novel therapeutic targets

The role of inflammation in cancer is a topic that has been investigated for many years. As established, inflammation emerges as a defining characteristic of cancer, presenting itself as a compelling target for therapeutic interventions in the realm of oncology. Controlling the tumor microenvironment (TME) has gained paramount significance, modifying not only the effectiveness of immunotherapy but also modulating the outcomes and prognoses of standard chemotherapy and other anticancer treatments. Immunotherapy has surfaced as a central focus within the domain of tumor treatments, using immune checkpoint inhibitors as cancer therapy. Immune checkpoints and their influence on the tumor microenvironment dynamic are presently under investigation, aiming to ascertain their viability as therapeutic interventions across several cancer types. Cancer presents a significant challenge in humans and cats, where female breast cancer ranks as the most prevalent malignancy and feline mammary carcinoma stands as the third most frequent. This review seeks to summarize the data about the immune checkpoints cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), lymphocyte activation gene-3 (LAG-3), programmed cell death protein-1 (PD-1), V-domain Ig suppressor of T cell activation (VISTA), and T-cell immunoglobulin and mucin domain 3 (TIM-3) respective ongoing investigations as prospective targets for therapy for human breast cancer, while also outlining findings from studies reported on feline mammary carcinoma (FMC), strengthening the rationale for employing FMC as a representative model in the exploration of human breast cancer.

Unravelling the potential of TIM-3 gene polymorphism in allogeneic hematopoietic stem cell transplantation - a preliminary study

BACKGROUND

T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) molecule is a key regulator of the immune response by exerting an inhibitory effect on various types of immune cells. Understanding the role of TIM-3 in hematopoietic stem cell transplantation (HSCT) may improve transplant outcomes. Our study evaluated the potential association between TIM-3 polymorphisms, namely rs1036199 (A > C) or rs10515746 (C > A), changes which are located in exon 3 and the promoter region of the TIM-3 gene, and post-HSCT outcomes.

METHODS

One-hundred and twenty allogeneic HSCT patients and their respective donors were enrolled and genotyped for TIM-3 single nucleotide polymorphisms (SNPs) using real-time PCR with TaqMan assays.

RESULTS

We found that the presence of the rare alleles and heterozygous genotypes of studied SNP in recipients tended to protect against or increase the risk for acute graft-versus-host disease (aGvHD). For the rs1036199 polymorphism, recipients with the AC heterozygous genotype (p = 0.0287) or carrying the rarer C allele (p = 0.0334) showed a lower frequency of aGvHD development along all I-IV grades. A similar association was detected for the rs10515746 polymorphism as recipients with the CA genotype (p = 0.0095) or the recessive A allele (p = 0.0117) less frequently developed aGvHD. Furthermore, the rarer A allele of rs10515746 SNP was also associated with a prolonged aGvHD-free survival (p = 0.0424). Cytomegalovirus (CMV) infection was more common in patients transplanted with TIM-3 rs10515746 mismatched donors (p = 0.0229) and this association was also found to be independent of HLA incompatibility and pre-transplant CMV-IgG status. Multivariate analyses confirmed the role of these recessive alleles and donor-recipient TIM-3 incompatibility as an independent factor in aGvHD and CMV development.

CONCLUSIONS

Polymorphism of TIM-3 molecule may affect the immune response in HSCT patients. The recessive alleles of rs1036199 and rs10515746 SNPs decreased the risk of developing aGvHD. TIM-3 donor-recipient genetic matching may also affect the risk of post-transplant CMV infection, indicating the potential value of genetic profiling in optimizing transplant strategies.

Effect of Cyclosporine A on Th1/Th2 Cytokine Production by Decidual Stromal Cells Mediated by Trophoblast-derived Galectin-9

This study aimed to investigate the effect of cyclosporine A (CsA) on secretion of Th1 and Th2 cytokines by decidual stromal cells (DSCs) mediated by galectin (Gal)-9.HTR8/SVneo cells and primary trophoblasts were used for in vitro studies. Gal-9 expression was measured using quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay, CsA was used to regulate Gal-9 expression in trophoblasts. DSCs were treated with trophoblast supernatant and changes in Th1 and Th2 cytokine levels were analyzed. Changes in DSC levels of the T-cell immunoglobulin mucin receptor 3 (TIM-3) levels in DSCs after treatment with Gal-9 were assessed. Western blotting and ERK and AKT inhibitors were used to assess the involvement of the corresponding signaling pathways. Gal-9 was expressed by both primary trophoblasts and HTR8/SVneo cells. CsA treatment increased Gal-9 secretion by trophoblasts, which in turn increased IL-6 (Th2 cytokine) and decreased TNF-α and IFN-γ (Th1 cytokines) secretion in DSCs. Upon downregulation of trophoblast Gal-9 secretion, DSCs secreted lower levels of Th2 cytokines and higher levels of Th1 cytokines, and the effect was reversed by addition of CsA. TIM-3 expression changed in parallel with Gal-9 secretion. CsA treatment upregulated expression of Gal-9 in trophoblasts, promoted secretion of Th2 cytokines, and inhibited secretion of Th1 cytokines via ERK signaling.

TIM-3 Expression in Endometriosis

PROBLEM

Endometriosis is a prevalent chronic gynecological disease linked to immune dysfunction. The protein T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) plays a crucial role in immune system balance. Malfunction of TIM-3 may result in excessive immune activation and inflammatory tissue damage. Given TIM-3's established role in the development of cancer and autoimmune diseases, we decided to study its role in women suffering from endometriosis.

STUDY METHOD

We included a total of 62 female patients, all of whom had undergone laparoscopic surgery. Of these, 47 had endometriosis and 15 did not. During surgery, we collected peritoneal fluid (PF) and peripheral blood (PB) samples from every patient for analysis using flow cytometry. To mark the samples, we used a panel of monoclonal antibodies and examined TIM-3 expression in their immune cells.

RESULTS

Endometriosis patients in PB demonstrated a significantly lower percentage of CD56+ T cells with TIM-3 expression. As endometriosis progressed through its stages, this expression lessened. This decrease was particularly notable in women with stage III/IV endometriosis. Additionally, both women diagnosed with intestinal endometriosis and those with recent endometriosis diagnoses showed a significantly reduced percentage of CD56+ T cells expressing TIM-3.

CONCLUSIONS

Patients with endometriosis exhibit diminished TIM-3 expression within circulating T cells. This warrants further investigation to discern whether it contributes to the progression of endometriosis, potentially through the amplification of autoreactive T cells and inflammation.

Immunotherapy combination approaches: mechanisms, biomarkers and clinical observations

The approval of the first immune checkpoint inhibitors provided a paradigm shift for the treatment of malignancies across a broad range of indications. Whereas initially, single-agent immune checkpoint inhibition was used, increasing numbers of patients are now treated with combination immune checkpoint blockade, where non-redundant mechanisms of action of the individual agents generally lead to higher response rates. Furthermore, immune checkpoint therapy has been combined with various other therapeutic modalities, including chemotherapy, radiotherapy and other immunotherapeutics such as vaccines, adoptive cellular therapies, cytokines and others, in an effort to maximize clinical efficacy. Currently, a large number of clinical trials test combination therapies with an immune checkpoint inhibitor as a backbone. However, proceeding without inclusion of broad, if initially exploratory, biomarker investigations may ultimately slow progress, as so far, few combinations have yielded clinical successes based on clinical data alone. Here, we present the rationale for combination therapies and discuss clinical data from clinical trials across the immuno-oncology spectrum. Moreover, we discuss the evolution of biomarker approaches and highlight the potential new directions that comprehensive biomarker studies can yield.

Porcine TLR8 signaling and its anti-infection function are disturbed by immune checkpoint receptor TIM-3 via inhibition of P13K-AKT pathway

Toll-like receptor 8 (TLR8), an important innate immune receptor recognizing single stranded RNA and the antiviral imidazoquinoline compounds, can activate intracellular signaling pathway and produce an inflammatory response to kill and eliminate pathogens. However, the molecular regulation mechanisms of TLR8 signaling and its anti-infection activity are not fully elucidated. Our previous transcriptome analysis of porcine TLR8 (pTLR8) signaling suggested the immune checkpoint receptor TIM-3 as the potential regulator for pTLR8. Here we investigated TIM-3 in the regulation of pTLR8 signaling and its anti-infection activity. Our results showed that porcine TIM-3 is upregulated by pTLR8 signaling and TIM-3 inhibits pTLR8 signaling activity in a negative feedback way. Accordingly, TIM-3 disturbs pTLR8 mediated anti-bacterial and anti-viral activity. Mechanistically, TIM-3 suppresses PI3K-AKT pathway by inhibiting the TLR8-PI3K p85 interaction and subsequent AKT phosphorylation which is essential for TLR8 signaling and anti-infection activity. Therefore, our study reveals new insights into innate immune TLR8 signaling and its anti-infection function.

TIM-3 transcriptomic landscape with clinical and immunomic correlates in cancer

TIM-3, an inhibitory checkpoint receptor, may invoke anti-PD-1/anti-PD-L1 immune checkpoint inhibitor (ICI) resistance. The predictive impact of TIM-3 RNA expression in various advanced solid tumors among patients treated with ICIs is yet to be determined, and their prognostic significance also remains unexplored. We investigated TIM-3 transcriptomic expression and clinical outcomes. We examined TIM-3 RNA expression data through the OmniSeq database. TIM-3 transcriptomic patterns were calibrated against a reference population (735 tumors), adjusted to internal housekeeping genes, and calculated as percentiles. Overall, 514 patients (31 cancer types; 489 patients with advanced/metastatic disease and clinical annotation) were assessed. Ninety tumors (17.5% of 514) had high (≥75th percentile RNA rank) TIM-3 expression. Pancreatic cancer had the greatest proportion of TIM-3 high expressors (36% of 55 patients). Still, there was variability within cancer types with, for instance, 12.7% of pancreatic cancers harboring low TIM-3 (<25th percentile) levels. High TIM-3 expression independently and significantly correlated with high PD-L2 RNA expression (odds ratio (OR) 9.63, 95% confidence interval (CI) 4.91-19.4, P<0.001) and high VISTA RNA expression (OR 2.71, 95% CI 1.43-5.13, P=0.002), all in multivariate analysis. High TIM-3 RNA did not correlate with overall survival (OS) from time of metastatic disease in the 272 patients who never received ICIs, suggesting that it is not a prognostic factor. However, high TIM-3 expression predicted longer median OS (but not progression-free survival) in 217 ICI-treated patients (P=0.0033; median OS, 2.84 versus 1.21 years (high versus not-high TIM-3)), albeit not retained in multivariable analysis. In summary, TIM-3 RNA expression was variable between and within malignancies, and high levels associated with high PD-L2 and VISTA checkpoints and with pancreatic cancer. Individual tumor immunomic assessment and co-targeting co-expressed checkpoints merits exploration in prospective trials as part of a precision immunotherapy strategy.

TCR β chain repertoire characteristic between healthy human CD4+ and CD8+ T cells

T cell is vital in the adaptive immune system, which relays on T-cell receptor (TCR) to recognize and defend against infection and tumors. T cells are mainly divided into well-known CD4+ and CD8+ T cells, which can recognize short peptide antigens presented by major histocompatibility complex (MHC) class II and MHC class I respectively in humoral and cell-mediated immunity. Due to the Human Leukocyte Antigen (HLA) diversity and restriction with peptides complexation, TCRs are quite diverse and complicated. To better elucidate the TCR in humans, the present study shows the difference between the TCR repertoire in CD4+ and CD8+ T cells from 30 healthy donors. The result showed count, clonality, diversity, frequency, and VDJ usage in CD4+ and CD8+ TCR-β repertoire is different, but CDR3 length is not. The Common Clone Cluster result showed that CD4+ and CD8+ TCR repertoires are connected separately between the bodies, which is odd considering the HLA diversity. More knowledge about TCR makes more opportunities for immunotherapy. The TCR repertoire is still a myth for discovery.

Therapeutic and immunomodulatory potentials of mesenchymal stromal/stem cells and immune checkpoints related molecules

Mesenchymal stromal/stem cells (MSCs) are used in many studies due to their therapeutic potential, including their differentiative ability and immunomodulatory properties. These cells perform their therapeutic functions by using various mechanisms, such as the production of anti-inflammatory cytokines, growth factors, direct cell-to-cell contact, extracellular vesicles (EVs) production, and mitochondrial transfer. However, mechanisms related to immune checkpoints (ICPs) and their effect on the immunomodulatory ability of MSCs are less discussed. The main function of ICPs is to prevent the initiation of unwanted responses and to regulate the immune system responses to maintain the homeostasis of these responses. ICPs are produced by various types of immune system regulatory cells, and defects in their expression and function may be associated with excessive responses that can ultimately lead to autoimmunity. Also, by expressing different types of ICPs and their ligands (ICPLs), tumor cells prevent the formation and durability of immune responses, which leads to tumors' immune escape. ICPs and ICPLs can be produced by MSCs and affect immune cell responses both through their secretion into the microenvironment or direct cell-to-cell interaction. Pre-treatment of MSCs in inflammatory conditions leads to an increase in their therapeutic potential. In addition to the effect that inflammatory environments have on the production of anti-inflammatory cytokines by MSCs, they can increase the expression of various types of ICPLs. In this review, we discuss different types of ICPLs and ICPs expressed by MSCs and their effect on their immunomodulatory and therapeutic potential.

Beyond PD(L)-1 Blockade in Microsatellite-Instable Cancers: Current Landscape of Immune Co-Inhibitory Receptor Targeting

High microsatellite instability (MSI-H) derives from genomic hypermutability due to deficient mismatch repair function. Colorectal (CRC) and endometrial cancers (EC) are the tumor types that more often present MSI-H. Anti-PD(L)-1 antibodies have been demonstrated to be agnostically effective in patients with MSI-H cancer, but 50-60% of them do not respond to single-agent treatment, highlighting the necessity of expanding their treatment opportunities. Ipilimumab (anti-CTLA4) is the only immune checkpoint inhibitor (ICI) non-targeting PD(L)-1 that has been approved so far by the FDA for MSI-H cancer, namely, CRC in combination with nivolumab. Anti-TIM3 antibody LY3321367 showed interesting clinical activity in combination with anti-PDL-1 antibody in patients with MSI-H cancer not previously treated with anti-PD(L)-1. In contrast, no clinical evidence is available for anti-LAG3, anti-TIGIT, anti-BTLA, anti-ICOS and anti-IDO1 antibodies in MSI-H cancers, but clinical trials are ongoing. Other immunotherapeutic strategies under study for MSI-H cancers include vaccines, systemic immunomodulators, STING agonists, PKM2 activators, T-cell immunotherapy, LAIR-1 immunosuppression reversal, IL5 superagonists, oncolytic viruses and IL12 partial agonists. In conclusion, several combination therapies of ICIs and novel strategies are emerging and may revolutionize the treatment paradigm of MSI-H patients in the future. A huge effort will be necessary to find reliable immune biomarkers to personalize therapeutical decisions.

Advances in immune checkpoint-based immunotherapies for multiple sclerosis: rationale and practice

Beyond the encouraging results and broad clinical applicability of immune checkpoint (ICP) inhibitors in cancer therapy, ICP-based immunotherapies in the context of autoimmune disease, particularly multiple sclerosis (MS), have garnered considerable attention and hold great potential for developing effective therapeutic strategies. Given the well-established immunoregulatory role of ICPs in maintaining a balance between stimulatory and inhibitory signaling pathways to promote immune tolerance to self-antigens, a dysregulated expression pattern of ICPs has been observed in a significant proportion of patients with MS and its animal model called experimental autoimmune encephalomyelitis (EAE), which is associated with autoreactivity towards myelin and neurodegeneration. Consequently, there is a rationale for developing immunotherapeutic strategies to induce inhibitory ICPs while suppressing stimulatory ICPs, including engineering immune cells to overexpress ligands for inhibitory ICP receptors, such as program death-1 (PD-1), or designing fusion proteins, namely abatacept, to bind and inhibit the co-stimulatory pathways involved in overactivated T-cell mediated autoimmunity, and other strategies that will be discussed in-depth in the current review. Video Abstract.

Tim-3 Is Differentially Expressed during Cell Activation and Interacts with the LSP-1 Protein in Human Macrophages

T-cell Immunoglobulin and Mucin Domain 3 (TIM-3) is an immune checkpoint receptor known to regulate T-cell activation and has been targeted for immunotherapy in cancer and other diseases. However, its expression and function in other cell types, such as macrophages, are poorly understood. This study investigated TIM-3 expression in human macrophages polarized to M1 (stimulated with IFN-γ and LPS) and M2 (stimulated with IL-4 and IL-13) phenotypes using an in vitro model. Our results show that M1 macrophages have a lower frequency of TIM-3+ cells compared to M2 macrophages at 48 and 72 hr poststimulation. Additionally, we observed differential levels of soluble ADAM 10, an enzyme responsible for TIM-3 release, in the supernatants of M1 and M2 macrophages at 72 hr. We also found that the TIM-3 intracellular tail might associate with lymphocyte-specific protein 1 (LSP-1), a protein implicated in cell motility and podosome formation. These findings enhance our understanding of TIM-3 function in myeloid cells such as macrophages and may inform the development of immunotherapies with reduced immune-related adverse effects.

Association of TIM-3 with anterior uveitis and associated systemic immune diseases: a Mendelian randomization analysis

Background

We aimed to investigate the causal association between TIM-3, an immune checkpoint inhibitor, and anterior uveitis (AU), as well as associated systemic immune diseases.

Materials and methods

We performed two-sample Mendelian randomization (MR) analyses to estimate the causal effects of TIM-3 on AU and three associated systemic diseases, namely ankylosing spondylitis (AS), Crohn's disease (CD), and ulcerative colitis (UC). Single-nucleotide polymorphisms (SNPs) associated with AU, AS, CD, and UC were selected as the outcomes: AU GWAS with 2,752 patients with acute AU accompanied with AS (cases) and 3,836 AS patients (controls), AS GWAS with 968 cases and 336,191 controls, CD GWAS with 1,032 cases and 336,127 controls, and UC GWAS with 2,439 cases and 460,494 controls. The TIM-3 dataset was used as the exposure (n = 31,684). Four MR methods, namely, inverse-variance weighting (IVW), MR-Egger regression, weighted median, and weighted mode, were used in this study. Comprehensive sensitivity analyses were conducted to estimate the robustness of identified associations and the potential impact of horizontal pleiotropy.

Results

Our studies show that TIM-3 is significantly associated with CD using the IVW method (OR = 1.001, 95% CI = 1.0002-1.0018, P-value = 0.011). We also found that TIM-3 may be a protective factor for AU although these results lacked significance (OR = 0.889, 95% CI = 0.631-1.252, P-value = 0.5). No association was observed between the genetic predisposition to particular TIM-3 and susceptibility to AS or UC in this study. No potential heterogeneities or directional pleiotropies were observed in our analyses.

Conclusion

According to our study, a small correlation was observed between TIM-3 expression and CD susceptibility. Additional studies in different ethnic backgrounds will be necessary to further explore the potential roles and mechanisms of TIM-3 in CD.

Identification of a novel MYC target gene set signature for predicting the prognosis of osteosarcoma patients

Osteosarcoma is a primary malignant tumor found mainly in teenagers and young adults. Patients have very little long-term survival. MYC controls tumor initiation and progression by regulating the expression of its target genes; thus, constructing a risk signature of osteosarcoma MYC target gene set will benefit the evaluation of both treatment and prognosis. In this paper, we used GEO data to download the ChIP-seq data of MYC to obtain the MYC target gene. Then, a risk signature consisting of 10 MYC target genes was developed using Cox regression analysis. The signature indicates that patients in the high-risk group performed poorly. After that, we verified it in the GSE21257 dataset. In addition, the difference in tumor immune function among the low- and high-risk populations was compared by single sample gene enrichment analysis. Immunotherapy and prediction of response to the anticancer drug have shown that the risk signature of the MYC target gene set was positively correlated with immune checkpoint response and drug sensitivity. Functional analysis has demonstrated that these genes are enriched in malignant tumors. Finally, STX10 was selected for functional experimentation. STX10 silence has limited osteosarcoma cell migration, invasion, and proliferation. Therefore, these findings indicated that the MYC target gene set risk signature could be used as a potential therapeutic target and prognostic indicator in patients with osteosarcoma.

Immune checkpoints on T and NK cells in the context of HBV infection: Landscape, pathophysiology and therapeutic exploitation

In hepatitis B virus (HBV) infection, the interplay between the virus and the host immune system is crucial in determining the pathogenesis of the disease. Patients who fail to mount a sufficient and sustained anti-viral immune response develop chronic hepatitis B (CHB). T cells and natural killer (NK) cells play decisive role in viral clearance, but they are defective in chronic HBV infection. The activation of immune cells is tightly controlled by a combination of activating and inhibitory receptors, called immune checkpoints (ICs), allowing the maintenance of immune homeostasis. Chronic exposure to viral antigens and the subsequent dysregulation of ICs actively contribute to the exhaustion of effector cells and viral persistence. The present review aims to summarize the function of various ICs and their expression in T lymphocytes and NK cells in the course of HBV infection as well as the use of immunotherapeutic strategies targeting ICs in chronic HBV infection.

Decreased expression of ADAM10 on monocytes is associated with chronic allograft dysfunction in kidney transplant recipients

BACKGROUND

Chronic allograft dysfunction (CAD) is a common cause of allograft loss in kidney transplant recipients (KTRs). Our previous study found that elevated serum soluble T cell immunoglobulin mucin-3 (sTim-3) was positively associated with the severity of CAD in KTRs. sTim-3 was reported to be generated from ADAM10/ADAM17-mediated ectodomain shedding of membrane Tim-3 (mTim-3) in humans. However, whether mTim-3 shedding-related molecules participate in the progression of CAD remains unknown. Here, we explored the relationships between different forms of Tim-3, including mTim-3 on different peripheral blood cell subsets, serum and urine sTim-3, and ADAM10/17 expression and active status to investigate their roles in CAD.

METHODS

63 KTRs with stable grafts, 91 KTRs with CAD and 42 healthy controls (HCs) were enrolled. Total Tim-3, pADAM10/17 and mADAM10/17 proteins were semiquantified by western blot. Serum and urine sTim-3 concentrations were determined by ELISA. mTim-3 and ADAM10/17 expression on leukocyte subpopulations was determined by flow cytometry.

RESULTS

The KTR groups displayed significantly higher levels of urine sTim-3 pg/μmol creatinine than the HC group, while no difference was found between the two KTR groups. KTRs with CAD presented reduced nonactive pADAM10 protein but unaltered active mADAM10 when compared to the Stable group; no difference was found between the KTR groups regarding total Tim-3 and p/m ADAM17 protein levels. In addition, the CAD group showed lower mTim-3 expression on BDCA3⁺ DC than the Stable group; no other difference was observed in its expression on B, T, NK, NKT, monocyte subsets and other DC subsets among groups. With the deterioration of allograft function, ADAM10 expression densities on classical, intermediate, and non-classical monocytes were significantly decreased. Correlation analyses revealed that eGFR and serum sTim-3 exhibited weak to modest correlations with ADAM10 on monocyte and DC subsets.

CONCLUSIONS

Our data indicated that ADAM10, especially its decreased expression on monocytes, may play an important role in the progression of CAD in KTRs. However, whether there is an interaction between ADAM10 and mTim-3 in the pathogenesis of CAD in KTRs needs to be further studied.

Blood Clot Scaffold Loaded with Liposome Vaccine and siRNAs Targeting PD-L1 and TIM-3 for Effective DC Activation and Cancer Immunotherapy

Tumor vaccines have been showing a relatively weak response rate in cancer patients, while deficiencies in delivery efficiency to dendritic cells (DCs), as well as DC-intrinsic immunosuppressive signals, contribute to a great extent. In this work, we report an implantable blood clot loaded with liposomes-protamine-hyaluronic acid nanoparticles (LPH NPs) containing vaccine (LPH-vaccine) and LPH NPs containing siRNA (LPH-siRNA) for synergistic DC recruitment and activation. The subcutaneously implanted blood clot scaffold can recruit abundant immune cells, particularly DCs, to form a DC-rich environment in vivo. Within the scaffold, LPH-vaccine effectively delivers antigens and adjuvants to the recruited DCs and induces the maturation of DCs. More importantly, LPH-siRNA that targets programmed death-ligand 1 (PD-L1) and T cell immunoglobulin and mucin-containing molecule 3 (TIM-3) can reduce immunosuppressive signals in mature DCs and prevent the DCs from expressing a regulatory program in the scaffold. The activated DCs correlate with an improved magnitude and efficacy of T cell priming, resulting in the production of tumor antigen-specific T cells in multiple mouse models. Our strategy can also be used for patient-tailored therapy by change of tumor neoantigens, suggesting a promising strategy for cancer therapy in the clinic.

Negative Regulation of RIG-I by Tim-3 Promotes H1N1 Infection

The mechanisms by which retinoic acid-inducible gene I (RIG-I), a critical RNA virus sensor, is regulated in many biological and pathological processes remain to be determined. Here, we demonstrate that T cell immunoglobulin and mucin protein-3 (Tim-3), an immune checkpoint inhibitor, mediates infection tolerance by suppressing RIG-I-type I interferon pathway. Overexpression or blockade of Tim-3 affects type I interferon expression, virus replication, and tissue damage in mice following H1N1 infection. Tim-3 signaling decreases RIG-I transcription via STAT1 in macrophages and promotes the proteasomal dependent degradation of RIG-I by enhancing K-48-linked ubiquitination via the E3 ligase RNF-122. Silencing RIG-I reversed Tim-3 blockage-mediated upregulation of type I interferon in macrophages. We thus identified a new mechanism through which Tim-3 mediates the immune evasion of H1N1, which may have clinical implications for the treatment of viral diseases.

Immune checkpoint molecules in prevention and development of asthma

Allergic asthma is a respiratory disease initiated by type-2 immune responses characterized by secretion of alarmins, interleukin-4 (IL-4), IL-5, and IL-13, eosinophilic inflammation, and airway hyperresponsiveness (AHR). Immune checkpoints (ICPs) are inhibitory or stimulatory molecules expressed on different immune cells, tumor cells, or other cell types that regulate immune system activation and maintain immune homeostasis. Compelling evidence indicates a key role for ICPs in both the progression and prevention of asthma. There is also evidence of asthma development or exacerbation in some cancer patients receiving ICP therapy. The aim of this review is to provide an updated overview of ICPs and their roles in asthma pathogenesis, and to assess their implications as therapeutic targets in asthma.

The Expanding Spectrum of Autoinflammatory Diseases

Autoinflammatory diseases are systemic disorders caused by genetic or acquired abnormalities in certain signaling pathways of the innate immune system. Dysregulated activation of the inflammasome, i.e. molecular platforms responsible for the activation of caspase-1 and production of interleukin-1β, causes autoinflammation. Familial Mediterranean fever (FMF), the most common genetic autoinflammatory disease, is characterized by a periodic fever and serositis. The complex and heterogeneous genetic background of Japanese FMF patients, accompanied by potential overlap with other rheumatic diseases, suggests crosstalk between genetic and environmental factors. Recently, FMF has been recognized as being part of a spectrum of autoinflammatory syndromes named pyrin-associated autoinflammatory diseases. The discovery of a new monogenic autoinflammatory disease, A20 haploinsufficiency, may provide novel insights into early-onset Behçet's-like diseases. In contrast, adult-onset Still's disease and Schnitzler's syndrome are acquired autoinflammatory diseases without a monogenic abnormality. Although the concept of autoinflammatory diseases originally applied to monogenic hereditary recurrent fevers, it has been expanded to include non-genetic complex autoinflammatory diseases. Information concerning monogenic autoinflammatory diseases may prove useful for elucidating the molecular mechanisms underlying non-genetic autoinflammatory diseases.

Increased CEACAM1 expression on peripheral blood neutrophils in patients with rheumatoid arthritis

Altered expression of adhesion molecules in immune cells has been demonstrated in rheumatoid arthritis (RA). Carcinoembryonic-antigen-related cell-adhesion molecule 1 (CEACAM1) is an adhesion molecule that acts as a coinhibitory receptor in the immune system. We investigated the role of CEACAM1 in immune cell subsets of patients with RA. Peripheral blood was obtained from 37 patients with RA and 20 healthy controls (HC). The expression of CEACAM1 and T-cell immunoglobulin mucin domain molecule (TIM) -3 on peripheral blood mononuclear cells and neutrophils was analyzed by flow cytometry. Intracellular TIM-3 expression was analyzed using cellular lysates by Western blot analysis. Serum levels of soluble CEACAM1 (sCEACAM1) were estimated by an enzyme-linked immunosorbent assay. CEACAM1 expression was not detected in peripheral blood mononuclear cells, including in CD14(+) monocytes and CD3(+) lymphocytes isolated from patients with RA or HC. However, substantial cell-surface expression of CEACAM1 was detected in peripheral blood neutrophils, and it was significantly elevated in samples from patients with RA without remission compared to those in remission. There was no significant difference in serum levels of sCEACAM1 between patients with RA and HC. Cell-surface expression of TIM-3 was not detected in peripheral blood neutrophils from patients with RA or HC but was seen in CD14(+) monocytes. However, there was no significant difference in TIM-3 expression on monocytes between patients with RA and HC. Our data indicate that cell-surface expression of CEACAM1 on peripheral blood neutrophils are higher in patients with RA and that it is associated with rheumatoid inflammation. Further studies are needed to explore the potential role of CEACAM1 in rheumatoid inflammatory pathways.

Multiplexed Digital Spatial Protein Profiling Reveals Distinct Phenotypes of Mononuclear Phagocytes in Livers with Advanced Fibrosis

Background and Aims: Intrahepatic mononuclear phagocytes (MPs) are critical for the initiation and progression of liver fibrosis. In this study, using multiplexed digital spatial protein profiling, we aimed to derive a unique protein signature predicting advanced liver fibrosis. Methods: Snap-frozen liver tissues from various chronic liver diseases were subjected to spatially defined protein-based multiplexed profiling (Nanostring GeoMX^TM). A single-cell RNA sequencing analysis was performed using Gene Expression Omnibus (GEO) datasets from normal and cirrhotic livers. Results: Sixty-four portal regions of interest (ROIs) were selected for the spatial profiling. Using the results from the CD68⁺ area, a highly sensitive and specific immune-related protein signature (CD68, HLA-DR, OX40L, phospho-c-RAF, STING, and TIM3) was developed to predict advanced (F3 and F4) fibrosis. A combined analysis of single-cell RNA sequencing data from GEO datasets (GSE136103) and spatially-defined, protein-based multiplexed profiling revealed that most proteins upregulated in F0-F2 livers in portal CD68⁺ cells were specifically marked in tissue monocytes, whereas proteins upregulated in F3 and F4 livers were marked in scar-associated macrophages (SAMacs) and tissue monocytes. Internal validation using mRNA expression data with the same cohort tissues demonstrated that mRNA levels for TREM2, CD9, and CD68 are significantly higher in livers with advanced fibrosis. Conclusions: In patients with advanced liver fibrosis, portal MPs comprise of heterogeneous populations composed of SAMacs, Kupffer cells, and tissue monocytes. This is the first study that used spatially defined protein-based multiplexed profiling, and we have demonstrated the critical difference in the phenotypes of portal MPs between livers with early- or late-stage fibrosis.

Enhanced Inhibitory Effect of DC-CIK Cells on Lung Adenocarcinoma via Anti-Tim-3 Antibody and Antiprogrammed Cell Death-1 Antibody and Possible Mechanism

Objective

To investigate the effect and mechanism of blocking the signaling pathways of the T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) and programmed death protein 1 (PD-1) in dendritic cell-cytokine induced killer (DC-CIK) cells on human lung adenocarcinoma A549 cells.

Methods

Peripheral blood mononuclear cells (PBMCs) were isolated and induced into mature DC-CIK cells by cytokines in vitro. After blocking the Tim-3 and PD-1 signaling transduction pathways with anti-Tim-3 and anti-PD-1 antibodies, DC-CIK cells were coincubated with A549 cells. The killing effect of DC-CIK cells against A549 cells was measured by a CCK-8 assay. The impact of DC-CIK cells on the invasion and migration ability of A549 cells was detected by the Transwell test. The apoptosis rate of DC-CIK cells and the ratio of CD4⁺, CD8⁺, and DC-CIK cell subsets were determined by flow cytometry. The cell proliferation of DC-CIK was detected by the CCK-8 assay.

Results

The antibodies of anti-Tim-3 antibody and anti-PD-1 could block Tim-3⁺ and PD-1⁺ DC-CIK cells and could significantly increase the killing effect of DC-CIK cells on A549 cells. The number of A549 cells under the microporous membrane of the Transwell chamber was reduced considerably in invasion and migration tests. Anti-Tim-3 and anti-PD-1 antibodies significantly reduced apoptosis of DC-CIK cells. No significant differences were observed in the ratios of CD4⁺ and CD8⁺ DC-CIK cell subsets or the proliferation capacity of DC-CIK cells in each group.

Conclusion

Blocking the Tim-3 and PD-1 signaling pathways of DC-CIK cells with antibodies can enhance the killing ability of DC-CIK cells in A549 cells and significantly suppress the invasion and migration ability of A549 cells. The potential mechanism may be related to reduced apoptosis of DC-CIK cells.

Galectin-9 contributes to the pathogenesis of atopic dermatitis via T cell immunoglobulin mucin-3

Background

Atopic dermatitis (AD), a common type 2 inflammatory disease, is driven by T helper (T_H) 2/T_H22polarization and cytokines.Galectin-9 (Gal-9), via its receptor T cell immunoglobulin- and mucin-domain-containing molecule-3 (TIM-3), can promote T_H2/T_H22 immunity. The relevance of this in AD is largely unclear.

Objectives

To characterize the role of TIM-3 and Gal-9 in the pathogenesis of AD and underlying mechanisms.

Methods

We assessed the expression of Gal-9 and TIM-3 in 30 AD patients, to compare them with those of 30 healthy controls (HC) and to explore possible links with disease features including AD activity (SCORAD), IgE levels, and circulating eosinophils and B cells. We also determined the effects of Gal-9 on T cells from the AD patients.

Results

Our AD patients had markedly higher levels of serum Gal-9 and circulating TIM-3-expressing T_H1 and T_H17 cells than HC. Gal-9 and TIM-3 were linked to high disease activity, IgE levels, and circulating eosinophils and/or B cells. The rates of circulating TIM-3-positive CD4⁺ cells were positively correlated with rates of T_H2/T_H22 cells and negatively correlated with rates of T_H1/T_H17 cells. Gal-9 inhibited the proliferation and induced the apoptosis of T cells in patients with AD, especially in those with severe AD.

Conclusion

Our findings suggest thatGal-9, via TIM-3, contributes to the pathogenesis of AD by augmenting T_H2/T_H22 polarization through the downregulation of T_H1/T_H17immunity. This makes Gal-9 and TIM-3 interesting to explore further, as possible drivers of disease and targets of novel AD treatment.

A comprehensive profiling of the immune microenvironment of breast cancer brain metastases

BACKGROUND

Despite potential clinical implications, the complexity of breast cancer (BC) brain metastases (BM) immune microenvironment is poorly understood. Through multiplex immunofluorescence, we here describe the main features of BCBM immune microenvironment (density and spatial distribution) and evaluate its prognostic impact.

METHODS

Sixty BCBM from patients undergoing neurosurgery at three institutions (2003-2018) were comprehensively assessed using two multiplex immunofluorescence panels (CD4, CD8, Granzyme B, FoxP3, CD68, pan-cytokeratin, DAPI; CD3, PD-1, PD-L1, LAG-3, TIM-3, CD163, pan-cytokeratin, DAPI). The prognostic impact of immune subpopulations and cell-to-cell spatial interactions was evaluated.

RESULTS

Subtype-related differences in BCBM immune microenvironment and its prognostic impact were observed. While in HR-/HER2- BM and HER2+ BM, higher densities of intra-tumoral CD8+ lymphocytes were associated with significantly longer OS (HR 0.16 and 0.20, respectively), in HR+/HER2- BCBMs a higher CD4+FoxP3+/CD8+ cell ratio in the stroma was associated with worse OS (HR 5.4). Moreover, a higher density of intra-tumoral CD163+ M2-polarized microglia/macrophages in BCBMs was significantly associated with worse OS in HR-/HER2- and HR+/HER2- BCBMs (HR 6.56 and 4.68, respectively), but not in HER2+ BCBMs. In HER2+ BCBMs, multiplex immunofluorescence highlighted a negative prognostic role of PD-1/PD-L1 interaction: patients with a higher percentage of PD-L1+ cells spatially interacting with (within a 20 µm radius) PD-1+ cells presented a significantly worse OS (HR 4.60).

CONCLUSIONS

Our results highlight subtype-related differences in BCBM immune microenvironment and identify two potential therapeutic targets, M2 microglia/macrophage polarization in HER2- and PD-1/PD-L1 interaction in HER2+ BCBMs, which warrant future exploration in clinical trials.

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

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

Next generation of immune checkpoint molecules in maternal-fetal immunity

Successful pregnancy is a unique situation requires the maternal immune system to recognize and tolerate a semi-identical fetus and allow normal invasion of trophoblast cells. Although efforts have been made, the deep mechanisms of the maternal-fetal crosstalk have not yet been fully deciphered. Immune checkpoint molecules (ICMs) are a group of negative modulators of the immune response that avoid immune damage. They have been extensively studied in the fields of oncology and transplantation, while the latest evidence suggests that they are closely associated with pregnancy outcomes via multiple inhibitory mechanisms. Although studies have mostly demonstrated the regulatory role of the well-known PD-1, CTLA-4 at the maternal-fetal interface, what is unique about the newly discovered multiple ICMs remains a mystery. Here, we review the latest knowledge on ICMs, focusing on the first generation of checkpoints (PD-1, CTLA-4) and the next generation (Tim-3, Tigit, Lag-3, VISTA) highlighting their immunoregulatory roles in maternal-fetal tolerance and decidual vascular remodeling, and their involvement in pathological pregnancies. The content covers three aspects: the characteristics they possess, the dynamic expression profile of their expression at the maternal-fetal interface, and their involvement in pathological pregnancy. In immunotherapy strategies for pregnancy complications, upregulation of immune checkpoints may play a role. Meanwhile, the impact on pregnancy outcomes when using ICMs in clinical cancer treatment during pregnancy is a topic worth exploring. These may serve as a guide for future basic research and clinical applications of maternal-fetal immunity.

Tim-3 Relieves Experimental Autoimmune Encephalomyelitis by Suppressing MHC-II

Tim-3, an immune checkpoint inhibitor, is widely expressed on the immune cells and contributes to immune tolerance. However, the mechanisms by which Tim-3 induces immune tolerance remain to be determined. Major histocompatibility complex II (MHC-II) plays a key role in antigen presentation and CD4⁺T cell activation. Dysregulated expressions of Tim-3 and MHC-II are associated with the pathogenesis of many autoimmune diseases including multiple sclerosis. Here we demonstrated that, by suppressing MHC-II expression in macrophages via the STAT1/CIITA pathway, Tim-3 inhibits MHC-II-mediated autoantigen presentation and CD4⁺T cell activation. As a result, overexpression or blockade of Tim-3 signaling in mice with experimental autoimmune encephalomyelitis (EAE) inhibited or increased MHC-II expression respectively and finally altered clinical outcomes. We thus identified a new mechanism by which Tim-3 induces immune tolerance in vivo and regulating the Tim-3-MHC-II signaling pathway is expected to provide a new solution for multiple sclerosis treatment.

In Acute Dengue Infection, High TIM-3 Expression May Contribute to the Impairment of IFNγ Production by Circulating Vδ2 T Cells

γδ T cells are innate cells able to quickly eliminate pathogens or infected/tumoral cells by their antiviral and adjuvancy activities. The role of γδ T cells during Dengue Viral Infection (DENV) infection is not fully elucidated. Nevertheless, human primary γδ T cells have been shown to kill in vitro DENV-infected cells, thus highlighting their possible antiviral function. The aim of this work was to characterize the phenotype and function of Vδ2 T cells in DENV patients. Fifteen DENV patients were enrolled for this study and peripheral blood mononuclear cells (PBMC) were used to analyze Vδ2-T-cell frequency, differentiation profile, activation/exhaustion status, and functionality by multiparametric flow cytometry. Our data demonstrated that DENV infection was able to significantly reduce Vδ2-T-cell frequency and to increase their activation (CD38 and HLA-DR) and exhaustion markers (PD-1 and TIM-3). Furthermore, Vδ2 T cells showed a reduced capability to produce IFN-γ after phosphoantigenic stimulation that can be associated to TIM-3 expression. Several studies are needed to depict the possible clinical impact of γδ-T-cell impairment on disease severity and to define the antiviral and immunoregulatory activities of γδ T cells in the first phases of infection.

Novel immune targets for the treatment of triple-negative breast cancer

INTRODUCTION

To overcome mechanisms of primary and secondary resistance to the anti-tumor immune response, novel targets such as ICOS, LAG3, and TIM3 are currently being explored at preclinical and early-phase clinical levels.

AREAS COVERED

This article examines the landscape of the immune therapeutics investigated in early-phase clinical trials for TNBC. Preclinical rationale is provided for each immune target, predominant expression, and function. Clinical implications and preliminary available trial results are discussed and finally, we reflect on aspects of future expectations and challenges in this field.

EXPERT OPINION

Several immune strategies have been investigated in TNBC, including co-inhibitory molecules beyond PD1-PD-L1 axis, co-stimulatory checkpoints, cancer vaccines, adoptive cell transfer, combination therapies, as well as different routes of administration. Most of approaches showed signs of anti-cancer activity and a good safety profile in early-phase clinical trials. Since IO provided benefit only to a small subgroup of TNBC patients so far, identifying predictive biomarkers is a priority to refine patient-selection. Data from ongoing clinical trials, with the gradually improving interpretation of the breast tumor immune environment, will hopefully refine the role of new immune targets for the treatment of TNBC.

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.

Monocytes differentiated into macrophages and dendritic cells in the presence of human IFN-λ3 or IFN-λ4 show distinct phenotypes

Human IFN-λ4 is expressed by only a subset of individuals who possess the ΔG variant allele at the dinucleotide polymorphism rs368234815. Recent genetic studies have shown an association between rs368234815 and different infectious and inflammatory disorders. It is not known if IFN-λ4 has immunomodulatory activity. The expression of another type III IFN, IFN-λ3, is also controlled by genetic polymorphisms that are strongly linked to rs368234815. Therefore, it is of interest to compare these two IFNs for their effects on immune cells. Herein, using THP-1 cells, it was confirmed that IFN-λ4 could affect the differentiation status of macrophage-like cells and dendritic cells (DCs). The global gene expression changes induced by IFN-λ4 were also characterized in in vitro generated primary macrophages. Next, human PBMC-derived CD14+ monocytes were used to obtain M1 and M2 macrophages and DCs in the presence of IFN-λ3 or IFN-λ4. These DCs were cocultured with CD4+ Th cells derived from allogenic donors and their in vitro cytokine responses were measured. The specific activity of recombinant IFN-λ4 was much lower than that of IFN-λ3, as shown by induction of IFN-stimulated genes. M1 macrophages differentiated in the presence of IFN-λ4 showed higher IL-10 secretion than those differentiated in IFN-λ3. Coculture experiments suggested that IFN-λ4 could confer a Th2-biased phenotype to allogenic Th cells, wherein IFN-λ3, under similar circumstances, did not induce a significant bias toward either a Th1 or Th2 phenotype. This study shows for the first time that IFN-λ4 may influence immune responses by immunomodulation.

Phase I/Ib Clinical Trial of Sabatolimab, an Anti-TIM-3 Antibody, Alone and in Combination with Spartalizumab, an Anti-PD-1 Antibody, in Advanced Solid Tumors

PURPOSE

Sabatolimab (MBG453) and spartalizumab are mAbs that bind T-cell immunoglobulin domain and mucin domain-3 (TIM-3) and programmed death-1 (PD-1), respectively. This phase I/II study evaluated the safety and efficacy of sabatolimab, with or without spartalizumab, in patients with advanced solid tumors.

PATIENTS AND METHODS

Primary objectives of the phase I/Ib part were to characterize the safety and estimate recommended phase II dose (RP2D) for future studies. Dose escalation was guided by a Bayesian (hierarchical) logistic regression model. Sabatolimab was administered intravenously, 20 to 1,200 mg, every 2 or 4 weeks (Q2W or Q4W). Spartalizumab was administered intravenously, 80 to 400 mg, Q2W or Q4W.

RESULTS

Enrolled patients (n = 219) had a range of cancers, most commonly ovarian (17%) and colorectal cancer (7%); patients received sabatolimab (n = 133) or sabatolimab plus spartalizumab (n = 86). The MTD was not reached. The most common adverse event suspected to be treatment-related was fatigue (9%, sabatolimab; 15%, combination). No responses were seen with sabatolimab. Five patients receiving combination treatment had partial responses (6%; lasting 12-27 months) in colorectal cancer (n = 2), non-small cell lung cancer (NSCLC), malignant perianal melanoma, and SCLC. Of the five, two patients had elevated expression of immune markers in baseline biopsies; another three had >10% TIM-3-positive staining, including one patient with NSCLC who received prior PD-1 therapy.

CONCLUSIONS

Sabatolimab plus spartalizumab was well tolerated and showed preliminary signs of antitumor activity. The RP2D for sabatolimab was selected as 800 mg Q4W (alternatively Q3W or Q2W schedules, based on modeling), with or without 400 mg spartalizumab Q4W.

Ubiquitination and degradation of NF90 by Tim-3 inhibits antiviral innate immunity

Nuclear factor 90 (NF90) is a novel virus sensor that serves to initiate antiviral innate immunity by triggering stress granule (SG) formation. However, the regulation of the NF90-SG pathway remains largely unclear. We found that Tim-3, an immune checkpoint inhibitor, promotes the ubiquitination and degradation of NF90 and inhibits NF90-SG-mediated antiviral immunity. Vesicular stomatitis virus (VSV) infection induces the up-regulation and activation of Tim-3 in macrophages, which in turn recruit the E3 ubiquitin ligase TRIM47 to the zinc finger domain of NF90 and initiate a proteasome-dependent degradation via K48-linked ubiquitination at Lys297. Targeted inactivation of Tim-3 enhances the NF90 downstream SG formation by selectively increasing the phosphorylation of protein kinase R and eukaryotic translation initiation factor 2α, the expression of SG markers G3BP1 and TIA-1, and protecting mice from VSV challenge. These findings provide insights into the crosstalk between Tim-3 and other receptors in antiviral innate immunity and its related clinical significance.

Increased Tim-3+ monocytes/macrophages are associated with disease severity in patients with IgA nephropathy

T-cell immunoglobulin and mucin-domain-containing protein-3 (Tim-3) plays multiple important roles in immune response and participates in the pathogenesis of various inflammatory diseases by regulating macrophage polarization. However, its functions in the development of IgA nephropathy (IgAN) are still unclear. In this study, changes in the relative levels of Tim-3⁺ monocytes/macrophages in peripheral blood and renal tissue, and their clinical significance in patients with IgAN were investigated. The expression of CD68 and Tim-3 in macrophages from patients with IgAN was determined via immunohistochemistry and immunofluorescence staining assays. Peripheral blood of 48 patients with biopsy-proven IgAN and 18 healthy controls (HCs) was collected to determine the frequency of circulating CD14⁺Tim-3⁺ cells using flow cytometry, before and after 24 weeks of prednisolone treatment. Serum interleukin (IL)-10 and tumor necrosis factor α (TNF-α) levels were measured using enzyme-linked immunosorbent assays. The potential association between clinical signs and Tim-3⁺ monocytes/macrophages was analyzed. The percentages of circulating CD14⁺Tim-3⁺ monocytes were higher in samples from patients with IgAN than in those from HCs and were positively associated with the pathological features (segmental glomerulosclerosis and tubular atrophy/interstitial fibrosis) of IgAN, according to the Oxford classification. Tissue staining assays revealed cells positive for both CD68 and Tim-3 in tubulointerstitial lesions of IgAN patients. In addition, elevated levels of serum IL-10 and TNF-α were detected in these patients in comparison to HCs. Furthermore, the frequency of circulating CD14⁺Tim-3⁺ monocytes had a positive correlation with levels of 24-h urinary protein and serum IL-10, and was negatively associated with renal function. After 24 weeks of treatment with prednisolone, the percentages of CD14⁺Tim-3⁺ cells were significantly reduced. In summary, our findings indicate that Tim-3⁺ monocytes/macrophages might be involved in the pathogenesisof IgAN and could be used as a potential indicator to evaluate disease severity.

Generation of TIM3 inhibitory single-domain antibodies to boost the antitumor activity of chimeric antigen receptor T cells

Targeting inhibitory immune checkpoint molecules has significantly altered cancer treatment regimens. T cell immunoglobulin and mucin domain 3 (TIM3) is one of the major inhibitory immune checkpoints expressed on T cells. Blocking the engagement of TIM3 and its inhibitory ligand galectin-9 may potentiate the effects of immunotherapy or overcome the adaptive resistance to the therapeutic blockade of programmed cell death protein 1, cytotoxic T-lymphocyte-associated protein 4, B- and T-lymphocyte attenuator and lymphocyte-activation gene 3, amongst others, as each of these immune checkpoints harbors unique properties that set it apart from the rest. Heavy chain variable fragment (VH)-derived single-domain antibodies (sdAbs) represent a class of expanding drug candidates. These sdAbs have unique advantages, including their minimal size in the antibody class, ease of expression, broad scope for modular structure design and re-engineering, and excellent tumor penetration. In the present study, two sdAbs, TIM3-R23 and TIM3-R53, were generated by immunizing rabbits with the recombinant extracellular domain of TIM3 and applying phage display technology. These sdAbs were easily expressed in mammalian cells. The purified sdAbs were able to bind to both recombinant and cell surface TIM3, and blocked it from binding to the ligand galectin-9. In vivo studies demonstrated that TIM3-R53 was able to potentiate the antitumor activity of chimeric antigen receptor T cells that targeted mesothelin. In conclusion, the results of the present study suggested that TIM3-R53 may be a novel and attractive immune checkpoint inhibitor against TIM3, which is worthy of further investigation.

Decidual Natural Killer Cells: A Good Nanny at the Maternal-Fetal Interface During Early Pregnancy

Decidual natural killer (dNK) cells are the tissue-resident and major subpopulation of NK cells at the maternal-fetal interface. It has been demonstrated that dNK cells play pivotal roles in pregnancy, including keeping maternal-fetal immune tolerance, promoting extravillous trophoblast (EVT) cell invasion, and driving uterine spiral artery remodeling. However, the molecular mechanisms haven't been elucidated until recent years. In this review, we systemically introduce the generation, subsets, and surface or soluble molecules of dNK cells, which are critical for maintaining the functions of dNK cells. Further, new functions of dNK cells including well-controlled cytotoxicity, immunosurveillance and immunotrophism supporting via the cell-cell interaction between dNK cells and EVT cells are mainly focused. The molecular mechanisms involved in these functions are also illustrated. Moreover, pregnancy-associated diseases caused by the dNK cells abnormalities are discussed. It will be important for future investigations about the mechanism of maintenance of pregnancy and parturition and potential clinical applications of dNK cells.

Modulation of CXCR1 and CXCR3 expression on NK cells via Tim-3 in a murine model of primary biliary cholangitis

Tim-3, which is expressed on a variety of innate immune cells including NK cells, plays a key role in many autoimmune diseases. However, the immunomodulatory actions of Tim-3 on NK cells in primary biliary cholangitis (PBC) remain uncertain. Using a murine model of PBC we evaluated the expression of Tim-3 and its ligand Gal-9 in peripheral blood, liver, and spleen. Additionally, we studied Tim-3 regulation of chemokine receptors (CXCR1 and CXCR3) in vitro. Flow cytometric analysis indicated large numbers of infiltrating NK cells in the liver which exhibited high expression of Tim-3 and CXCR3. Moreover, we found overexpression of CXCR1 in liver tissue and liver-derived NK cells in PBC mice. We also observed lower levels of soluble Tim-3 in the serum of PBC mice. In vitro experiments with liver-derived NK cells from PBC mice indicated that CXCR3 was up-regulated by treatment with recombinant mouse TIM-3 Fc (rmTim-3 Fc) to activate the Tim-3 pathway. Furthermore, stimulating normal mouse spleen NK cells with poly I:C resulted in elevated expression of CXCR1 and interferon-γ release. Nonetheless, adding rmTim-3 Fc or rmGal-9 significantly down-regulated CXCR1 expression and IFN-γ release in NK cells activated by poly I:C, proposing a means to exploit the Tim-3 pathway to reverse responses in NK cells. In conclusion, our data demonstrate that dysregulation of Tim-3/Gal-9 is involved in modulating the local immune microenvironment in PBC mice. Our findings highlight the potential of Tim-3 pathway to modulate chemokine responses in NK cells during autoimmunity.

Peripheral Injection of Tim-3 Antibody Attenuates VSV Encephalitis by Enhancing MHC-I Presentation

Viral encephalitis is the most common cause of encephalitis. It is responsible for high morbidity rates, permanent neurological sequelae, and even high mortality rates. The host immune response plays a critical role in preventing or clearing invading pathogens, especially when effective antiviral treatment is lacking. However, due to blockade of the blood-brain barrier, it remains unclear how peripheral immune cells contribute to the fight against intracerebral viruses. Here, we report that peripheral injection of an antibody against human Tim-3, an immune checkpoint inhibitor widely expressed on immune cells, markedly attenuated vesicular stomatitis virus (VSV) encephalitis, marked by decreased mortality and improved neuroethology in mice. Peripheral injection of Tim-3 antibody enhanced the recruitment of immune cells to the brain, increased the expression of major histocompatibility complex-I (MHC-I) on macrophages, and as a result, promoted the activation of VSV-specific CD8⁺ T cells. Depletion of macrophages abolished the peripheral injection-mediated protection against VSV encephalitis. Notably, for the first time, we found a novel post-translational modification of MHC-I by Tim-3, wherein, by enhancing the expression of MARCH9, Tim-3 promoted the proteasome-dependent degradation of MHC-I via K48-linked ubiquitination in macrophages. These results provide insights into the immune response against intracranial infections; thus, manipulating the peripheral immune cells with Tim-3 antibody to fight viruses in the brain may have potential applications for combating viral encephalitis.

Newly characterized decidual Tim-3+ Treg cells are abundant during early pregnancy and driven by IL-27 coordinately with Gal-9 from trophoblasts

STUDY QUESTION

What is the mechanism of Tim-3+ regulatory T (Treg)-cell accumulation in the decidua during early pregnancy and is its disruption associated with recurrent pregnancy loss (RPL)?

SUMMARY ANSWER

IL-27 and Gal-9 secreted by trophoblasts activate the Tim-3 signaling pathway in CD4+ T cells and Treg cells and so promote accumulation of Tim-3+ Treg cells, the abnormal expression of IL-27 and Gal-9 is associated with impaired immunologic tolerance in RPL patients.

WHAT IS KNOWN ALREADY

Tim-3+ Treg cells are better suppressors of Teff cell proliferation, and display higher proliferative activity than Tim-3- Treg cells. Tim-3+ Treg cells are tissue-specific promoters of T-cell dysfunction in many tumors. These cells express a unique factor that influences and shapes the tumor microenvironment.

STUDY DESIGN, SIZE, DURATION

The animal study included 80 normal pregnant mice. In human study, decidua tissues in the first trimester for flow cytometry analysis were collected from 32 normal pregnant women and 23 RPL patients. Placenta tissues for immunohistochemistry analysis were collected from 15 normal pregnant women. Placenta tissues for western blot analysis were collected from 5 normal pregnant women, 5 RPL patients and 5 women who have experienced one miscarriage. Blood samples for in vitro experiments were collected from 30 normal pregnant women. This study was performed between January 2017 and March 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In this study, we investigated the kinetics of Tim-3+ CD4+ T-cell accumulation, and the proportions of Tim-3+ Treg cells throughout murine pregnancies using flow cytometry. We compared Tim-3 expression on decidual CD4+ T cells and Treg cells during normal pregnancies with expression on the same cell populations in women suffering from RPL. IL-27 and Gal-9 transcription and protein expression in the placenta were determined by RT-PCR and western blot, respectively. An in vitro co-culture model consisting of peripheral CD4+ T cells and primary trophoblasts from early pregnancy was used to mimic the maternal-fetal environment.

MAIN RESULTS AND THE ROLE OF CHANCE

The percentage of Tim-3+ Treg cells present in mouse uteri fluctuates as gestation proceeds but does not change in the spleen. Levels of Tim3+ Treg cells in uteri peaked at pregnancy Day 6.5 (E 6.5), then progressively diminished, and fell to non-pregnant levels by E18.5. In pregnant mice, Tim-3+ Treg cells constituted 40-70% of Treg cells in uteri but were present at much lower abundance in spleens. About 60% of decidual Treg cells were Tim-3 positive at E6.5. Of these decidual Tim3+ Treg cells, nearly 90% were PD-1 positive. However, only about 16% of Tim3- Treg cells expressed PD-1. Blocking the Tim-3 signaling pathway decreased the proportion of Treg cells and led to embryo resorption. Moreover, much lower Tim-3 expression was observed on CD4+ T cells and Treg cells in women who had suffered from RPL at 6-9 gestational weeks compared with those who had normal pregnancies at matched gestations. In a normal pregnancy, Tim-3 expression on decidual CD4+ T cells is induced initially by IL-27. Then Gal-9-Tim-3 interaction promotes differentiation of decidual Tim-3+ CD4+ T cells into Treg cells. IL-27 and Gal-9 cooperatively induced Tim-3+ Treg cells in vitro.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

We did not investigate the kinetics of human decidual Tim-3+ CD4+ T and Tim-3+ Treg cell populations throughout pregnancy due to limited availability of second and third trimester decidua. In addition, functional suppressive data on the decidual Tim-3+ Treg cells are lacking due to limited and low quantities of these cells in decidua.

WIDER IMPLICATIONS OF THE FINDINGS

These findings might have therapeutic clinical implications in RPL.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by research grants from the National Natural Science Foundation of China (No. 81871186) and National Key Research & Developmental Program of China (2018YFC1003900, 2018YFC1003904). The authors declare no conflict of interest.

Correlation of Tim-3 expression with chemokine levels for predicting the prognosis of patients with glioblastoma

Glioblastoma (GBM) immunotherapy, which blocks the checkpoint inhibitor molecule T cell immunoglobulin domain and mucin domain-3 (Tim-3), has potential therapeutic applications. However, not all patients do benefit from the targeted therapy. This study aimed to explore Tim-3 expression correlated chemokine profiles and immune cell infiltration and investigate their potential as prognostic markers of glioblastoma (GBM) immunotherapy. We analyzed transcriptional data of GBM from TCGA database, to measure Tim-3 expression by R package DESeq2 analysis and observed differentially expressed genes in GBM samples with high Tim-3 expression levels. We also probed the relative gene enrichment pathways. Tim-3 expression was evident in biological processes including the recruitment of immune cells. We also identified some chemokines related to Tim-3 expression. The expression levels of CCL18, CXCL13 and CCL7 were significantly higher in GBM tissues with high Tim-3 expression than in GBM tissues with low Tim-3 expression. In addition, exploring the relationship between immune cell infiltration and Tim-3 expression suggested that Tim-3 expression was positively related to significant immune cell infiltration.

Tim-3 promotes tube formation and decreases tight junction formation in vascular endothelial cells

As a negative immune checkpoint molecule, T-cell immunoglobulin domain and mucin domain containing molecule-3 (Tim-3) has been found to serve a crucial role in immune escape and tumour progression. Previous studies have reported that Tim-3 is important to endothelial cells and it has also been demonstrated to be involved in numerous types of human diseases, including melanoma, lymphoma, rickettsial infection and atherosclerosis; however, its exact mechanism of action remains largely unknown. In the present study, Tim-3 was overexpressed in vascular endothelial human lung microvascular endothelial cells (HMVECs) and human umbilical vein endothelial cells (HUVECs), and in vitro assays were used to determine that Tim-3 promoted cell proliferation, migration, invasion and tube formation through activating cyclin D1 (CCND1), Ras homolog gene family member A and vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2). Additionally, Tim-3 decreased tight junction (TJ) formation and the transepithelial resistance (TER) of endothelial cells by decreasing the expression levels of TJ protein 2, Occludin and claudin 1 (CLND1). In conclusion, these findings suggested that Tim-3 may exert a positive role in angiogenesis and a negative role in TJ formation in vascular endothelial cells, which may provide novel strategies for the treatment of Tim-3-associated diseases.

Emerging Immunotherapy for Acute Myeloid Leukemia

Several immune checkpoint molecules and immune targets in leukemic cells have been investigated. Recent studies have suggested the potential clinical benefits of immuno-oncology (IO) therapy against acute myeloid leukemia (AML), especially targeting CD33, CD123, and CLL-1, as well as immune checkpoint inhibitors (e.g., anti-PD (programmed cell death)-1 and anti-CTLA4 (cytotoxic T-lymphocyte-associated protein 4) antibodies) with or without conventional chemotherapy. Early-phase clinical trials of chimeric antigen receptor (CAR)-T or natural killer (NK) cells for relapsed/refractory AML showed complete remission (CR) or marked reduction of marrow blasts in a few enrolled patients. Bi-/tri-specific antibodies (e.g., bispecific T-cell engager (BiTE) and dual-affinity retargeting (DART)) exhibited 11-67% CR rates with 13-78% risk of cytokine-releasing syndrome (CRS). Conventional chemotherapy in combination with anti-PD-1/anti-CTLA4 antibody for relapsed/refractory AML showed 10-36% CR rates with 7-24 month-long median survival. The current advantages of IO therapy in the field of AML are summarized herein. However, although cancer vaccination should be included in the concept of IO therapy, it is not mentioned in this review because of the paucity of relevant evidence.

The Search for an Interesting Partner to Combine with PD-L1 Blockade in Mesothelioma: Focus on TIM-3 and LAG-3

Malignant pleural mesothelioma (MPM) is an aggressive cancer that is causally associated with previous asbestos exposure in most afflicted patients. The prognosis of patients remains dismal, with a median overall survival of only 9-12 months, due to the limited effectiveness of any conventional anti-cancer treatment. New therapeutic strategies are needed to complement the limited armamentarium against MPM. We decided to focus on the combination of different immune checkpoint (IC) blocking antibodies (Abs). Programmed death-1 (PD-1), programmed death ligand-1 (PD-L1), T-cell immunoglobulin mucin-3 (TIM-3), and lymphocyte activation gene-3 (LAG-3) blocking Abs were tested as monotherapies, and as part of a combination strategy with a second IC inhibitor. We investigated their effect in vitro by examining the changes in the immune-related cytokine secretion profile of supernatant collected from treated allogeneic MPM-peripheral blood mononuclear cell (PBMC) co-cultures. Based on our in vitro results of cytokine secretion, and flow cytometry data that showed a significant upregulation of PD-L1 on PBMC after co-culture, we chose to further investigate the combinations of anti PD-L1 + anti TIM-3 versus anti PD-L1 + anti LAG-3 therapies in vivo in the AB1-HA BALB/cJ mesothelioma mouse model. PD-L1 monotherapy, as well as its combination with LAG-3 blockade, resulted in in-vivo delayed tumor growth and significant survival benefit.

The potential for immune checkpoint modulators in cerebrovascular injury and inflammation

Introduction: Neuroinflammation has been linked to poor neurologic and functional outcomes in many cerebrovascular disorders. Immune checkpoints are upregulated in the setting of traumatic brain injury, intracerebral hemorrhage, ischemic stroke, central nervous systems vasculitis, and post-hemorrhagic vasospasm, and are potential mediators of pathologic inflammation. Burgeoning evidence suggests that immune checkpoint modulation is a promising treatment strategy to decrease immune cell recruitment, cytokine secretion, brain edema, and neurodegeneration.Areas covered: This review discusses the role of immune checkpoints in neuroinflammation, and the potential for therapeutic immune checkpoint modulation in inflammatory cerebrovascular disorders. A search of Pubmed and clinicaltrials.gov was performed to find relevant literature published within the last 50 years.Expert opinion: The clinical success of immune-activating checkpoint modulators in human cancers has shown the immense clinical potential of checkpoint-based immunotherapy. Given that checkpoint blockade can also precipitate a pathologic pro-inflammatory or autoimmune response, it is plausible that these pathways may also be targeted to quell aberrant inflammation. A limited but growing number of studies suggest that immune checkpoints play a critical role in regulating the immune response in the central nervous system in a variety of contexts, and that immune-deactivating checkpoint modulators may be a promising treatment strategy for acute and chronic neuroinflammation in cerebrovascular disorders.

Association of soluble T cell immunoglobulin domain and mucin-3 (sTIM-3) and mac-2 binding protein glycosylation isomer (M2BPGi) in patients with autoimmune hepatitis

Background

Autoimmune hepatitis (AIH) is a disorder of unknown etiology in which immune-mediated liver injury progress to cirrhosis or hepatocellular carcinoma (HCC). The aim of the present study was to determine whether circulating soluble TIM3 (sTIM3) is elevated in patients with AIH patients and whether sTIM-3 levels are associated with clinical parameters of AIH.

Methods

We enrolled 123 Japanese patients with AIH who were identified from the National Hospital Organization–AIH-liver–network database, as well as 32 patients with chronic hepatitis C (CHC), 30 patients with primary biliary cholangitis (PBC) and healthy control subjects. Serum sTIM-3 concentrations were quantified by ELISA.

Results

Serum levels of sTIM-3 were significantly higher in AIH patients (median 4865 pg/ml; [interquartile range (IQR); 3122–7471]) compared to those in CHC (1026 pg/ml [IQR: 806–1283] p<0.001), PBC (2395 pg/ml [IQR: 2012–3422] p<0.001) or healthy controls (1285 pg/ml [IQR: 1098–1812] p<0.001). In AIH group, serum sTIM-3 were correlated with alanine aminotransferase (ALT), or total bilirubin (TB) and negatively correlated with serum levels of albumin (Alb). Serum levels of sTIM-3 were also strongly correlated with Mac-2 binding protein glycosylation isomer (M2BPGi) levels, but did not correlate with the histological grade of liver fibrosis. Steroid treatment of AIH patients significantly reduced serum sTIM-3 levels (2147±623pg/ml versus 1321±378pg/ml, p<0.001).

Conclusions

Circulating sTIM-3 levels were elevated in AIH patients and are associated with AIH disease activity and AIH-related liver damage. These findings indicate that serum sTIM-3 correlated with disease status of AIH and could be useful biomarkers to detect autoimmune-mediated liver injury. Our data suggest a possible link between the TIM-3/GAL-9 pathway and AIH severity or phenotype, and further investigations of the TIM-3 pathway and AIH pathophysiology is warranted.

Acute Myeloid Leukemia Stem Cells: The Challenges of Phenotypic Heterogeneity

Patients suffering from acute myeloid leukemia (AML) show highly heterogeneous clinical outcomes. Next to variabilities in patient-specific parameters influencing treatment decisions and outcome, this is due to differences in AML biology. In fact, different genetic drivers may transform variable cells of origin and co-exist with additional genetic lesions (e.g., as observed in clonal hematopoiesis) in a variety of leukemic (sub)clones. Moreover, AML cells are hierarchically organized and contain subpopulations of more immature cells called leukemic stem cells (LSC), which on the cellular level constitute the driver of the disease and may evolve during therapy. This genetic and hierarchical complexity results in a pronounced phenotypic variability, which is observed among AML cells of different patients as well as among the leukemic blasts of individual patients, at diagnosis and during the course of the disease. Here, we review the current knowledge on the heterogeneous landscape of AML surface markers with particular focus on those identifying LSC, and discuss why identification and targeting of this important cellular subpopulation in AML remains challenging.

Tim-3 Promotes Listeria monocytogenes Immune Evasion by Suppressing Major Histocompatibility Complex Class I

BACKGROUND

T-cell immunoglobulin and mucin protein 3 (Tim-3) is an immune checkpoint inhibitor that has therapeutic implications for many tumors and infectious diseases. However, the mechanisms by which Tim-3 promotes immune evasion remain unclear.

METHODS

In this study, we demonstrated that Tim-3 inhibits the expression of major histocompatibility complex class I (MHC-I) in macrophages at both the messenger ribonucleic acid and protein levels by inhibiting the STAT1-NLRC5 signaling pathway.

RESULTS

As a result, MHC-I-restricted antigen presentation by macrophages was inhibited by Tim-3 both in vitro and in a Listeria monocytogenes infection model in vivo. Systemic overexpression of Tim-3 or specific knockout of Tim-3 in macrophages significantly attenuated or enhanced CD8+ T-cell activation and infection damage in L monocytogenes-infected mice, respectively.

CONCLUSIONS

Thus, we identified a new mechanism by which Tim-3 promotes L monocytogenes immune evasion. Further studies on this pathway might shed new light on the physio-pathological roles of Tim-3 and suggest new approaches for intervention.

Targeting NK Cell Inhibitory Receptors for Precision Multiple Myeloma Immunotherapy

Innate immune surveillance of cancer involves multiple types of immune cells including the innate lymphoid cells (ILCs). Natural killer (NK) cells are considered the most active ILC subset for tumor elimination because of their ability to target infected and malignant cells without prior sensitization. NK cells are equipped with an array of activating and inhibitory receptors (IRs); hence NK cell activity is controlled by balanced signals between the activating and IRs. Multiple myeloma (MM) is a hematological malignancy that is known for its altered immune landscape. Despite improvements in therapeutic options for MM, this disease remains incurable. An emerging trend to improve clinical outcomes in MM involves harnessing the inherent ability of NK cells to kill malignant cells by recruiting NK cells and enhancing their cytotoxicity toward the malignant MM cells. Following the clinical success of blocking T cell IRs in multiple cancers, targeting NK cell IRs is drawing increasing attention. Relevant NK cell IRs that are attractive candidates for checkpoint blockades include KIRs, NKG2A, LAG-3, TIGIT, PD-1, and TIM-3 receptors. Investigating these NK cell IRs as pathogenic agents and therapeutic targets could lead to promising applications in MM therapy. This review describes the critical role of enhancing NK cell activity in MM and discusses the potential of blocking NK cell IRs as a future MM therapy.