Search

Neuroblastoma is the most common extracranial childhood solid tumor. The majority of high-risk neuroblastoma is resistant/refractory to the current high intensity therapy, and the survival of these patients remains poor for the last three decades. To effectively treat these extremely unfavorable neuroblastomas, innovative immunotherapy approaches would be the most promising. In this article, we discuss the identity of tumor-infiltrating effector cells and immunosuppressive cells in high-risk neuroblastoma. Neuroblastoma is unique in that it expresses little or no classical HLA Class I and II. In contrast, high-risk neuroblastomas express the stress-responsive non-classical Class I, HLA-E molecule. HLA-E is the ligand of activating receptors NKG2C/E that are expressed on memory NK cells, CD8+T cells and CD4 CTLs. By examining a comprehensive RNA-seq gene expression dataset, we detected relatively high levels of CD4 expression in high-risk neuroblastoma tissues. The majority of CD4+ cells were CD3+, and thus they were likely tumor-associated CD4+T cells. In addition, high-level of both CD4 and NKG2C/E expression was associated with prolonged survival of the high-risk neuroblastoma patients, but CD8 levels were not, further suggesting that the CD4+ NKG2C/E+ T cells or CD4 CTL conferred cytotoxicity against the neuroblastoma cells. However, this T cell mediated- "protective effect" declined over time, in part due to the progressive formation of immunosuppressive tumor microenvironment. These observations suggest that to improve survival of high-risk neuroblastoma patients, it is essential to gain insights into how to enhance CD4 CTL cytotoxicity and control the immunosuppressive tumor microenvironment during the course of the disease. [ABSTRACT FROM AUTHOR]

Class-I restricted T cell-associated molecule (CRTAM) is a member of the immunoglobulin superfamily, and it is closely related to nectin-like protein. CRTAM is expressed in activated CD8 T cells, NKT cells, NK cells and in a subpopulation CD4 T cells. In this study, we produce as recombinant proteins, the Ig-domains of CRTAM (IgV–IgC), the IgV, and the IgC. These proteins were successfully purified in the soluble fraction only if the stalk region was included. The recombinant CRTAM recognizes its ligand nectin-like 2 in a cell-free system. We also demonstrate that the IgC domain of CRTAM is recognized by the anti-hCRTAM monoclonal antibody C8 with a 0.62 nM affinity. In conclusion, the stalk region of CRTAM provides solubility for the expression of its Ig-domains as recombinant proteins. [ABSTRACT FROM AUTHOR]

• The immunomodulatory subtype of triple negative breast cancer（TNBC） exhibits promising effectiveness in immunotherapy. • CRTAM induces STAT1 phosphorylation and upregulation of interferon-stimulated genes. • CRTAM enhances the infiltration of immune cells, particularly CD8+ T cells. • CRTAM may serve as a potential biomarker for predicting the efficacy of immunotherapy in TNBC. The immunomodulatory (IM) subtype of triple negative breast cancer (TNBC) exhibits high expression of immune cell signaling genes and is more responsive to immunotherapy. However, the specific mechanism underlying this phenomenon remains unclear. One of the potential key genes appears to be the cytotoxic and regulatory T cell molecule (CRTAM). A cohort of 360 previously untreated TNBC patients from Fudan University Shanghai Cancer Center (FUSCC) underwent RNA sequencing analysis of their primary tumor tissue. Combined with three RNA-seq datasets obtained from the GEO database, a LASSO regression analysis was conducted to identify genes specific to the IM type of TNBC. Our findings revealed elevated CRTAM expression in the IM-type TNBC, which correlated with a favorable overall survival and recurrence-free survival in TNBC patients. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated a strong association between CRTAM and immune responses as well as immune system processes. Notably, CRTAM overexpression induced STAT1 phosphorylation and upregulation of interferon-stimulated genes. We also found that CRTAM enhanced tumor-associated immune cell infiltration, especially CD8+ T cells, which may be related to the increased expression of MHC class I molecules caused by CRTAM overexpression. These results suggest that CRTAM may serve as a potential biomarker for predicting the efficacy of immunotherapy in TNBC. [ABSTRACT FROM AUTHOR]

The gastrointestinal tract hosts the largest collection of commensal microbes in the body. Infections at this site can cause significant perturbations in the microbiota, known as dysbiosis, that facilitate the expansion of pathobionts, and can elicit inappropriate immune responses that impair the intestinal barrier function. Dysbiosis typically occurs during intestinal infection with Toxoplasma gondii. Host resistance to T. gondii depends on a potent Th1 response. In addition, a Th17 response is also elicited. How Th17 cells contribute to the host response to T. gondii remains unclear. Here we show that class I-restricted T cell-associated molecule (CRTAM) expression on T cells is required for an optimal IL-17 production during T. gondii infection. Moreover, that the lack of IL-17, results in increased immunopathology caused by an impaired antimicrobial peptide production and bacterial translocation from the intestinal lumen to the mesenteric lymph nodes and spleen.

The gastrointestinal tract hosts the largest collection of commensal microbes in the body. Infections at this site can cause significant perturbations in the microbiota, known as dysbiosis, that facilitate the expansion of pathobionts, and can elicit inappropriate immune responses that impair the intestinal barrier function. Dysbiosis typically occurs during intestinal infection with Toxoplasma gondii. Host resistance to T. gondii depends on a potent Th1 response. In addition, a Th17 response is also elicited. How Th17 cells contribute to the host response to T. gondii remains unclear. Here we show that class I-restricted T cell-associated molecule (CRTAM) expression on T cells is required for an optimal IL-17 production during T. gondii infection. Moreover, that the lack of IL-17, results in increased immunopathology caused by an impaired antimicrobial peptide production and bacterial translocation from the intestinal lumen to the mesenteric lymph nodes and spleen. [ABSTRACT FROM AUTHOR]

T cell activation is a multifaceted process that depends on the activation of the T cell receptor (TCR). However, other coreceptors are also strictly necessary to provide co-signals and modulate the immune response. However, to date, most of these coreceptors are unknown in fish or their information is very limited. Therefore, in this work, we have identified the cytotoxic and regulatory T cell molecule, CRTAM, and its ligand, the cell adhesion molecule 1, CADM1, in European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata); and evaluated their transcriptional levels. Both putative proteins showed the canonical architecture observed in mammals, where CRTAM exhibited two immunoglobulin domains and CADM1, both the a and b forms, exhibited three of these domains. In addition, phylogeny and synteny analyses showed their conservation throughout vertebrate evolution. We found constitutive expression of all three genes, with crtam and cadm1a being predominant in immune tissues such as spleen, thymus and head-kidney (HK), while cadm1b expression was more limited to the brain. In vitro , only the T cell mitogen phytohemagglutinin (PHA) up-regulated the transcription of crtam and cadm1a in HK leucocytes. Nodavirus (NNV) infection elicited an up-regulation of crtam and cadm1a in brain and HK, appearing earlier in seabream than in seabass, which could explain the resistance of seabream to the development of nodavirus disease. In addition, they are up-regulated during the innate cell-mediated cytotoxic response in seabream but not in seabass. Altogether, our data seem to indicate that CRTAM is more related to the innate cytotoxicity in seabream and more in the specific and T cell-mediated cytotoxicity in seabass. Our results highlight the importance of CRTAM and CADM1 as important molecules in the activation of T lymphocytes in seabass and seabream, but further studies are needed. • CRTAM and CADM1 genes are present and well-conserved in seabream and seabass. • European seabass crtam is up-regulated by T cell mitogens. • CRTAM and CADM1a genes are mainly expressed in lymphoid tissues and brain. • Upon nodavirus infection, CRTAM is up-regulated earlier in seabream than in seabass. • CRTAM and CADM1a seem to be related to the cell-mediated cytotoxic response. [ABSTRACT FROM AUTHOR]

Type 1 diabetes (T1D) is an autoimmune disease that is characterized by the specific destruction of insulin-producing pancreatic cells. Invariant natural killer b T (iNKT) cells have been associated with development of T1D. Class I MHC- restricted T cell-associated molecule (CRTAM) is expressed on activated iNKT, CD8+, and CD4+ T cells, and it is associated with the pro-inflammatory profiles of these cells. Crtam gene expression in CD3+ lymphocytes from non-obese diabetic (NOD) mice is associated with T1D onset. However, expression of CRTAM on T cells from patients with T1D has not yet been evaluated. We compared iNKT cell (CD3+Vα24+Vβ11+) numbers and CRTAM expression in a Mexican population with recent-onset T1D and their first-degree relatives with control families. Remarkably, we found lower iNKT cell numbers in T1D families, and we identified two iNKT cell populations in some of the families. One iNKT cell population expressed high iTCR levels (iNKThi), whereas another expressed low levels (iNKTlo) and also expressed CRTAM. These findings support a probable genetic determinant of iNKT cell numbers and a possible role for these cells in T1D development. This study also suggests that CRTAM identifies recently activated iNKT lymphocytes. [ABSTRACT FROM AUTHOR]

T cell activation leads to the induction of genes that are required for appropriate immune responses. This includes CRTAM (Class-I MHC-restricted T cell associated molecule), a protein that plays a key role in T cell development, proliferation, and generating cell polarity during activation. We previously characterized the CRTAM promoter and described how AP-1 family members are important for inducing CRTAM expression upon antigenic activation. Here, we show that CRTAM is a molecular target for ZEB1 (zinc finger E-box-binding protein), a homeodomain/Zn finger transcription factor. Overexpression of ZEB1 repressed CRTAM promoter activity, as well as endogenous CRTAM levels in human T cells. ZEB1-mediated transcriptional repression was abolished when E-box-like elements in the CRTAM promoter are mutated. In summary, ZEB1 functions as a transcriptional repressor for the CRTAM gene in both non-stimulated and stimulated T cells, thereby modulating adaptive immune responses. [ABSTRACT FROM AUTHOR]

Abstract: CRTAM was reported as a novel receptor expressed in activated NKT and CD8 T lymphocytes. However, we have recently shown that it is also expressed in several non-immune tissues. In opposition to what has been stated for lymphoid cells, CRTAM expression is constitutive in epithelia, suggesting a role in cell–cell interactions. Given the importance of cell interactions during T lymphocyte development, we evaluated CRTAM during T lymphocyte ontogeny. Here we show that CRTAM has an unexpected constitutive expression in adult thymocytes and, remarkably, it is sustained during all stages of thymocyte development. CRTAM expression is restricted to CD8 and all DN subpopulations, with a consistent pattern from E13.5 stage to adult mice. Blocking CRTAM interaction with CADM1 impairs thymus growth, uncovering a novel role in thymus development, with a consequent impact in thymocyte maturation. Thus, CRTAM interaction with CADM1 is involved in structural maintenance of the thymic lobes. [Copyright &y& Elsevier]

Abstract: We have previously reported the characterization of a novel immunoglobulin supergene family member, designated class-I MHC-restricted T cell associated molecule (CRTAM). Here we further characterize human CRTAM and find that it is highly expressed in the cerebellum, notably in Purkinje neurons. We identify CRTAM as a new member of the nectin-like (Necls) family and find significant expression of Necl-2 (IGSF4), a protein known to bind CRTAM and another member of the nectin superfamily, in the cerebellum. These findings suggest that CRTAM/Necl-2 binding may contribute to neuronal interactions. We also show that, in the immune system, CRTAM expression is restricted to activated class-I MHC-restricted T cells, including NKT and CD8 T cells. CRTAM represents one of the most highly expressed surface markers of activated human CD8 T cells and NKT cells, suggesting it may have diagnostic uses in various human viral and autoimmune diseases. [Copyright &y& Elsevier]

Class-I Restricted T Cell-Associated Molecule (CRTAM) is a protein that is expressed after T cell activation. The interaction of CRTAM with its ligand, nectin-like 2 (Necl2), is required for the efficient production of IL-17, IL-22, and IFNγ by murine CD4 T cells, and it plays a role in optimal CD8 T and NK cell cytotoxicity. CRTAM promotes the pro-inflammatory cytokine profile; therefore, it may take part in the immunopathology of autoimmune diseases such as diabetes type 1 or colitis. Thus, antibodies that block the interaction between CRTAM and Necl2 would be useful for controlling the production of these inflammatory cytokines. In this work, using bioinformatics predictions, we identified three short disordered epitopes (sDE1-3) that are located in the Ig-like domains of murine CRTAM and are conserved in mammalian species. We performed a structural analysis by molecular dynamics simulations of sDE1 (QHPALKSSKY, Ig-like V), sDE2 (QRNGEKSVVK, Ig-like C1), and sDE3 (CSTERSKKPPPQI, Ig-like C1). sDE1, which is located within a loop of the contact interface of the heterotypic interaction with Nectl2, undergoes an order–disorder transition. On the contrary, even though sDE2 and sDE3 are flexible and also located within loops, they do not undergo order–disorder transitions. We evaluated the immunogenicity of sDE1 and sDE3 through the expression of these epitopes in chimeric L1 virus-like particles. We confirmed that sDE1 induces polyclonal antibodies that recognize the native folding of CRTAM expressed in activated murine CD4 T cells. In contrast, sDE3 induces polyclonal antibodies that recognize the recombinant protein hCRTAM-Fc, but not the native CRTAM. Thus, in this study, an exposed disordered epitope in the Ig-like V domain of CRTAM was identified as a potential site for therapeutic antibodies. [ABSTRACT FROM AUTHOR]