Activation of mitogen activated protein kinase-Erk kinase (MEK) increases T cell immunoglobulin mucin domain-3 (TIM-3) transcription in human T lymphocytes and a human mast cell line

TIM-3 as a promising target for cancer immunotherapy in a wide range of tumors

T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) expression has been a trending topic in recent years due to its differential expression in a wide range of neoplasms. TIM-3 is one of the key immune checkpoint receptors that interact with GAL-9, PtdSer, HMGB1 and CEACAM1. Initially identified on the surface of T helper 1 (Th1) lymphocytes and later on cytotoxic lymphocytes (CTLs), monocytes, macrophages, natural killer cells (NKs), and dendritic cells (DCs), TIM-3 plays a key role in immunoregulation. Recently, a growing body of evidence has shown that its differential expression in various tumor types indicates a specific prognosis for cancer patients. Here, we discuss which types of cancer TIM-3 can serve as a prognostic factor and the influence of coexpressed immune checkpoint inhibitors, such as LAG-3, PD-1, and CTLA-4 on patients' outcomes. Currently, experimental medicine involving TIM-3 has significantly enhanced the anti-tumor effect and improved patient survival. In this work, we summarized clinical trials incorporating TIM-3 targeting monoclonal and bispecific antibodies in monotherapy and combination therapy and highlighted the emerging role of cell-based therapies.

Past, Present and Future: The Relationship Between Circular RNA and Immunity

The immune system has evolved since the birth of humans. However, immune-related diseases have not yet been overcome due to the lack of expected indicators and targeting specificity of current medical technology, subjecting patients to very uncomfortable physical and mental experiences and high medical costs. Therefore, the requirements for treatments with higher specificity and indicative ability are raised. Fortunately, the discovery of and continuous research investigating circular RNAs (circRNAs) represent a promising method among numerous methods. Although circRNAs wear regarded as metabolic wastes when discovered, as a type of noncoding RNA (ncRNA) with a ring structure and wide distribution range in the human body, circRNAs shine brilliantly in medical research by virtue of their special nature and structure-determined functions, such as high stability, wide distribution, high detection sensitivity, acceptable reproducibility and individual differences. Based on research investigating the role of circRNAs in immunity, we systematically discuss the hotspots of the roles of circRNAs in immune-related diseases, including expression profile analyses, potential biomarker research, ncRNA axis/network construction, impacts on phenotypes, therapeutic target seeking, maintenance of nucleic acid stability and protein binding research. In addition, we summarize the current situation of and problems associated with circRNAs in immune research, highlight the applications and prospects of circRNAs in the treatment of immune-related diseases, and provide new insight into future directions and new strategies for laboratory research and clinical applications.

The Emerging Role of T-Cell Immunoglobulin Mucin-3 in Breast Cancer: A Promising Target For Immunotherapy

Cancer treatment through immune checkpoint receptor blockade has made significant advances in the recent years. However, resistance to the current immune checkpoint inhibitors (ICIs) has been observed in many patients, who consequently do not respond to these treatments. T-cell immunoglobulin mucin-3 (Tim-3) is a novel immune checkpoint molecule emerging as a potential therapeutic target for cancer immunotherapy. Epidemiologic findings reveal that genetic polymorphisms in the Tim-3 gene are associated with increased susceptibility to breast cancer. In patients with breast cancer, Tim-3 is expressed both on immune and tumor cells. Accumulating evidence demonstrates that Tim-3 can notably affect breast cancer treatment outcome and prognosis. Therefore, Tim-3 is being regarded as a high-potential target for improving breast cancer therapy. In this review, we summarize the role of Tim-3 in breast cancer and the regulation mechanisms of Tim-3 to furnish evidences for future research and therapy.

ERK is a Pivotal Player of Chemo-Immune-Resistance in Cancer

The extracellular signal-related kinases (ERKs) act as pleiotropic molecules in tumors, where they activate pro-survival pathways leading to cell proliferation and migration, as well as modulate apoptosis, differentiation, and senescence. Given its central role as sensor of extracellular signals, ERK transduction system is widely exploited by cancer cells subjected to environmental stresses, such as chemotherapy and anti-tumor activity of the host immune system. Aggressive tumors have a tremendous ability to adapt and survive in stressing and unfavorable conditions. The simultaneous resistance to chemotherapy and immune system responses is common, and ERK signaling plays a key role in both types of resistance. In this review, we dissect the main ERK-dependent mechanisms and feedback circuitries that simultaneously determine chemoresistance and immune-resistance/immune-escape in cancer cells. We discuss the pros and cons of targeting ERK signaling to induce chemo-immune-sensitization in refractory tumors.

Regulation of TIM-3 expression in a human T cell line by tumor-conditioned media and cyclic AMP-dependent signaling

T cell immunoglobulin and mucin domain-3 (TIM-3) expression increases in exhausted T cells, which inhibits T cell function. TIM-3 expression is supposedly up-regulated in tumor-bearing individuals via chronic antigenic stimulation of T cells. Considering the immunosuppressive nature of the tumor microenvironment, we investigated whether tumor-secreted molecules might enhance TIM-3 expression in Jurkat T cells. We observed that TIM-3 expression was increased by the activation of prostaglandin (PG) E₂ and cyclic AMP (cAMP) signaling pathways. Adenylate cyclase activation led to protein kinase A (PKA)-dependent upregulation of the TIM-3 minimal promoter region and of upstream conserved non-coding sequences. TIM-3 expression in Jurkat T cells was increased by the exposure to breast tumor cell-conditioned media partially through the interaction between PGE₂ and its receptor, EP4. Our results propose that tumor-secreted molecules such as PGE₂, which activates PKA and EPAC, may regulate TIM-3 expression in T cells.

TNFα blockade overcomes resistance to anti-PD-1 in experimental melanoma

Antibodies against programmed cell death-1 (PD-1) have considerably changed the treatment for melanoma. However, many patients do not display therapeutic response or eventually relapse. Moreover, patients treated with anti-PD-1 develop immune-related adverse events that can be cured with anti-tumor necrosis factor α (TNF) antibodies. Whether anti-TNF antibodies affect the anti-cancer immune response remains unknown. Our recent work has highlighted that TNFR1-dependent TNF signalling impairs the accumulation of CD8+ tumor-infiltrating T lymphocytes (CD8+ TILs) in mouse melanoma. Herein, our results indicate that TNF or TNFR1 blockade synergizes with anti-PD-1 on anti-cancer immune responses towards solid cancers. Mechanistically, TNF blockade prevents anti-PD-1-induced TIL cell death as well as PD-L1 and TIM-3 expression. TNF expression positively correlates with expression of PD-L1 and TIM-3 in human melanoma specimens. This study provides a strong rationale to develop a combination therapy based on the use of anti-PD-1 and anti-TNF in cancer patients.

Most melanoma patients do not respond to anti-PD1 therapy. Here, the authors show that TNFα blockade synergizes with anti-PD-1 by preventing anti-PD-1-induced CD8+ T cell death and TIM-3 expression on such cells.

Overcoming Oncogenic Mediated Tumor Immunity in Prostate Cancer

Immunotherapy is being tested intensively in clinical trials for prostate cancer; it includes immune checkpoint inhibition, prostate specific antigen (PSA) vaccines and dendritic cell-based strategies. Despite increasing evidence for clinical responses, the consensus of multiple trials is that prostate cancers are poorly responsive to immunotherapy. Prostate cancer has a high degree of pathological and genetic heterogeneity compared to other cancer types, which may account for immunotherapeutic resistance. This hypothesis also implies that select types of prostate tumors may be differentially responsive to immune-based strategies and that the clinical stage, pathological grade and underlying genetic landscape may be important criteria in identifying tumors that respond to immune therapies. One strategy is to target oncogenic driver pathways in combination with immunotherapies with the goal of overcoming tumor immunity and broadening the number of patients achieving a clinical response. In this analysis, we address the hypothesis that driver oncogenic signaling pathways regulate cancer progression, tumor immunity and resistance to current immune therapeutics in prostate cancer. We propose that increased responsiveness may be achieved through the combined use of immunotherapies and inhibitors targeting tumor cell autonomous pathways that contribute towards anti-tumor immunity in patients with prostate cancer.

The immune receptor Tim-3 acts as a trafficker in a Tim-3/galectin-9 autocrine loop in human myeloid leukemia cells

The immune receptor Tim-3 is often highly expressed in human acute myeloid leukemia (AML) cells where it acts as a growth factor and inflammatory receptor. Recently, it has been demonstrated that Tim-3 forms an autocrine loop with its natural ligand galectin-9 in human AML cells. However, the pathophysiological functions of Tim-3 in human AML cells remain unclear. Here, we report for the first time that Tim-3 is required for galectin-9 secretion in human AML cells. However, this effect is cell-type specific and was found so far to be applicable only to myeloid (and not, for example, lymphoid) leukemia cells. We concluded that AML cells might use Tim-3 as a trafficker for the secretion of galectin-9 which can then be possibly used to impair the anticancer activities of cytotoxic T cells and natural killer (NK) cells.

Tim-3 enhances FcεRI-proximal signaling to modulate mast cell activation

Phong et al. show that depending on the expression of p-Lyn, mast cell activation by antigen can result in dichotomous effects on mast cell function and signaling that can be accentuated by Tim-3 ligation.

T cell (or transmembrane) immunoglobulin and mucin domain protein 3 (Tim-3) has attracted significant attention as a novel immune checkpoint receptor (ICR) on chronically stimulated, often dysfunctional, T cells. Antibodies to Tim-3 can enhance antiviral and antitumor immune responses. Tim-3 is also constitutively expressed by mast cells, NK cells and specific subsets of macrophages and dendritic cells. There is ample evidence for a positive role for Tim-3 in these latter cell types, which is at odds with the model of Tim-3 as an inhibitory molecule on T cells. At this point, little is known about the molecular mechanisms by which Tim-3 regulates the function of T cells or other cell types. We have focused on defining the effects of Tim-3 ligation on mast cell activation, as these cells constitutively express Tim-3 and are activated through an ITAM-containing receptor for IgE (FcεRI), using signaling pathways analogous to those in T cells. Using a variety of gain- and loss-of-function approaches, we find that Tim-3 acts at a receptor-proximal point to enhance Lyn kinase-dependent signaling pathways that modulate both immediate-phase degranulation and late-phase cytokine production downstream of FcεRI ligation.

The transcription factor NFAT promotes exhaustion of activated CD8⁺ T cells

During persistent antigen stimulation, CD8(+) T cells show a gradual decrease in effector function, referred to as exhaustion, which impairs responses in the setting of tumors and infections. Here we demonstrate that the transcription factor NFAT controls the program of T cell exhaustion. When expressed in cells, an engineered form of NFAT1 unable to interact with AP-1 transcription factors diminished T cell receptor (TCR) signaling, increased the expression of inhibitory cell surface receptors, and interfered with the ability of CD8(+) T cells to protect against Listeria infection and attenuate tumor growth in vivo. We defined the genomic regions occupied by endogenous and engineered NFAT1 in primary CD8(+) T cells and showed that genes directly induced by the engineered NFAT1 overlapped with genes expressed in exhausted CD8(+) T cells in vivo. Our data show that NFAT promotes T cell anergy and exhaustion by binding at sites that do not require cooperation with AP-1.

The transcription factor NFAT promotes exhaustion of activated CD8⁺ T cells

During persistent antigen stimulation, CD8(+) T cells show a gradual decrease in effector function, referred to as exhaustion, which impairs responses in the setting of tumors and infections. Here we demonstrate that the transcription factor NFAT controls the program of T cell exhaustion. When expressed in cells, an engineered form of NFAT1 unable to interact with AP-1 transcription factors diminished T cell receptor (TCR) signaling, increased the expression of inhibitory cell surface receptors, and interfered with the ability of CD8(+) T cells to protect against Listeria infection and attenuate tumor growth in vivo. We defined the genomic regions occupied by endogenous and engineered NFAT1 in primary CD8(+) T cells and showed that genes directly induced by the engineered NFAT1 overlapped with genes expressed in exhausted CD8(+) T cells in vivo. Our data show that NFAT promotes T cell anergy and exhaustion by binding at sites that do not require cooperation with AP-1.

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

Tim-3 was initially identified on activated Th1, Th17, and Tc1 cells and induces T cell death or exhaustion after binding to its ligand, Gal-9. The observed relationship between dysregulated Tim-3 expression on T cells and the progression of many clinical diseases has identified this molecule as an important target for intervention in adaptive immunity. Recent data have shown that it also plays critical roles in regulating the activities of macrophages, monocytes, dendritic cells, mast cells, natural killer cells, and endothelial cells. Although the underlying mechanisms remain unclear, dysregulation of Tim-3 expression on these innate immune cells leads to an excessive or inhibited inflammatory response and subsequent autoimmune damage or viral or tumor evasion. In this review, we focus on the expression and function of Tim-3 on innate immune cells and discuss (1) how Tim-3 is expressed and regulated on different innate immune cells; (2) how it affects the activity of different innate immune cells; and (3) how dysregulated Tim-3 expression on innate immune cells affects adaptive immunity and disease progression. Tim-3 is involved in the optimal activation of innate immune cells through its varied expression. A better understanding of the physiopathological role of the Tim-3 pathway in innate immunity will shed new light on the pathogenesis of clinical diseases, such as autoimmune diseases, chronic viral infections, and cancer, and suggest new approaches to intervention.

Anti-inflammatory activities of Dictamnus dasycarpus Turcz., root bark on allergic contact dermatitis induced by dinitrofluorobenzene in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The root bark of Dictamnus dasycarpus Turcz. is widely used as a medicinal herb for treatment of skin diseases such as eczema, pruritus and urticaria in China, Japan and Korea.

MATERIALS AND METHODS

We investigated the effects of methanol extract of Dictamnus dasycarpus Turcz., root bark (MEDD) on ear thickness, ear weights, histopathological changes such as hyperplasia, edema, spongiosis and immune cell infiltration and cytokine productions in 1-fluoro-2,4-dinitrofluorobenzene (DNFB)-induced contact dermatitis (CD) mice. We also investigated its effects on degranulation of histamine and β-hexosaminidase and related mechanisms using RBL-2H3 cells.

RESULTS

Topical application of MEDD effectively inhibited enlargement of ear thickness and weight (P<0.05). MEDD treatment also inhibited hyperplasia, edema and spongiosis induced by DNFB. Treatment with 300 μg/ear of MEDD suppressed the increase in IFN-γ and TNF-α levels (P<0.05). In addition, treatment with >50 μg/mL MEDD reduced the level of β-hexosaminidase release, while >100 μg/mL MEDD lowered the level of histamine release in a dose-dependent manner (P<0.05). Finally, MEDD treatment prevented phosphorylation of p38 MAPK induced by phorbol 12-myristate 13-acetate (PMA) and calcium ionophore A23187 in RBL-2H3 cells.

CONCLUSIONS

These data indicate that root bark of Dictamnus dasycarpus Turcz. has the potential for use in the treatment of allergic skin diseases. Furthermore, they suggest that root bark of Dictamnus dasycarpus Turcz. is involved in decreasing degranulation of MCs via inhibition of the p38 MAPK pathway as well as in the inhibition of Th1 skewing reactions.

T Cell Immunoglobulin Mucin Domain (TIM)-3 Promoter Activity in a Human Mast Cell Line

T cell immunoglobulin mucin domain (TIM)-3 is an immunomodulatory molecule and upregulated in T cells by several cytokines. TIM-3 also influences mast cell function but its transcriptional regulation in mast cells has not been clarified. Therefore, we examined the transcript level and the promoter activity of TIM-3 in mast cells. The TIM-3 transcript level was assessed by real-time RT-PCR and promoter activity by luciferase reporter assay. TIM-3 mRNA levels were increased in HMC-1, a human mast cell line by TGF-β1 stimulation but not by stimulation with interferon (IFN)-α, IFN-λ, TNF-α, or IL-10. TIM-3 promoter -349~+144 bp region relative to the transcription start site was crucial for the basal and TGF-β1-induced TIM-3 promoter activities in HMC-1 cells. TIM-3 promoter activity was increased by overexpression of Smad2 and Smad4, downstream molecules of TGF-β1 signaling. Our results localize TIM-3 promoter activity to the region spanning -349 to +144 bp in resting and TGF-β1 stimulated mast cells.