Littérature scientifique sur le sujet « Mucin domain 1 (TIM-1) »

Polymorphisms in theT cell (or transmembrane) immunoglobulin and mucin domain 1(TIM-1) gene, particularly in the mucin domain, have been associated with atopy and allergic diseases in mice and human. Genetic- and antibody-mediated studies revealed that Tim-1 functions as a positive regulator of Th2 responses, while certain antibodies to Tim-1 can exacerbate or reduce allergic lung inflammation. Tim-1 can also positively regulate the function of B cells, NKT cells, dendritic cells and mast cells. However, the precise molecular mechanisms by which Tim-1 modulates immune cell function are currently unknown. In this study, we have focused on defining Tim-1-mediated signaling pathways that enhance mast cell activation through the high affinity IgE receptor (FceRI). Using a Tim-1 mouse model lacking the mucin domain (Tim-1Dmucin), we show for the first time that the polymorphic Tim-1 mucin region is dispensable for normal mast cell activation. We further show that Tim-4 cross-linking of Tim-1 enhances select signaling pathways downstream of FceRI in mast cells, including mTOR-dependent signaling, leading to increased cytokine production but without affecting degranulation.

Polymorphisms in theT cell (or transmembrane) immunoglobulin and mucin domain 1(TIM-1) gene, particularly in the mucin domain, have been associated with atopy and allergic diseases in mice and human. Genetic- and antibody-mediated studies revealed that Tim-1 functions as a positive regulator of Th2 responses, while certain antibodies to Tim-1 can exacerbate or reduce allergic lung inflammation. Tim-1 can also positively regulate the function of B cells, NKT cells, dendritic cells and mast cells. However, the precise molecular mechanisms by which Tim-1 modulates immune cell function are currently unknown. In this study, we have focused on defining Tim-1-mediated signaling pathways that enhance mast cell activation through the high affinity IgE receptor (FceRI). Using a Tim-1 mouse model lacking the mucin domain (Tim-1Dmucin), we show for the first time that the polymorphic Tim-1 mucin region is dispensable for normal mast cell activation. We further show that Tim-4 cross-linking of Tim-1 enhances select signaling pathways downstream of FceRI in mast cells, including mTOR-dependent signaling, leading to increased cytokine production but without affecting degranulation.

T cells play an important role in antitumor immunity, and the T cell immunoglobulin domain and the mucin domain protein-1 (TIM-1) on its surface, as a costimulatory molecule, has a strong regulatory effect on T cells. TIM-1 can regulate and enhance type 1 immune response of tumor association. Therefore, TIM-1 costimulatory pathways may be a promising therapeutic target in future tumor immunotherapy. This review describes the immune regulation and antitumor effect of TIM-1.

Abstract The T cell Immunoglobulin and Mucin-like domain (TIM) proteins are a family of receptors that bind phosphatidylserine (PS) and regulate adaptive and innate immune cell functions. We find that two TIM-specific motifs: a G(W/L/I/F)(F/M)ND (GWFNDor) sequence and four conserved cysteine residues in the FG and CC’ segments of the TIM IgV domain form the distinctive PS-binding pocket identified in TIM-PS co-crystal structures. Because BALB/c and C57BL/6 mice have significant polymorphisms in TIM-3 and TIM-1, we determined the haplotypes of immunologically diverse and genetically divergent mice. Despite a high degree of variation in the IgV domain and in the mucin like stalk, the GWFNDor motif is unmodified in all known polymorphisms of TIM-1, -3, and 4. We identified two genomic alterations that cause divergent expression profiles of TIM-1 in commonly studied mouse strains. A major polymorphism in mouse TIM-1 deletes 23 amino acids of the mucin domain, and is caused by a retroviral insertion in the C57BL/6 genome that prevents expression of part of the mucin domain. Genomic and phylogenetic analyses show that a sytenic locus encoding generally 3 TIMs (1, 3, and 4) is conserved from bony fish to primates, and with emergence of the GWFND-4 motif in the most primitive TIM loci in bony fish, and the TIM family occupies a distinct PS-binding branch among the family of V-domain receptors that modulate immune activation via lipid, glycan, or protein binding.

Chikungunya virus (CHIKV) is a re-emerging, mosquito-transmitted, enveloped positive stranded RNA virus. Chikungunya fever is characterized by acute and chronic debilitating arthritis. Although multiple host factors have been shown to enhance CHIKV infection, the molecular mechanisms of cell entry and entry factors remain poorly understood. The phosphatidylserine-dependent receptors, T-cell immunoglobulin and mucin domain 1 (TIM-1) and Axl receptor tyrosine kinase (Axl), are transmembrane proteins that can serve as entry factors for enveloped viruses. Previous studies used pseudoviruses to delineate the role of TIM-1 and Axl in CHIKV entry. Conversely, here, we use the authentic CHIKV and cells ectopically expressing TIM-1 or Axl and demonstrate a role for TIM-1 in CHIKV infection. To further characterize TIM-1-dependent CHIKV infection, we generated cells expressing domain mutants of TIM-1. We show that point mutations in the phosphatidylserine binding site of TIM-1 lead to reduced cell binding, entry, and infection of CHIKV. Ectopic expression of TIM-1 renders immortalized keratinocytes permissive to CHIKV, whereas silencing of endogenously expressed TIM-1 in human hepatoma cells reduces CHIKV infection. Altogether, our findings indicate that, unlike Axl, TIM-1 readily promotes the productive entry of authentic CHIKV into target cells.

Abstract Transmembrane, immunoglobulin and mucin domain (TIM)-1 belongs to a family of transmembrane proteins with emerging roles in immune modulation. As a putative atopy susceptibility gene, polymorphisms in human and mouse TIM-1 are associated with atopic diseases, including asthma and atopic dermatitis. Antibodies targeting different extracellular domains of Tim-1 either attenuated or exacerbated airway inflammation in a mouse model of asthma. Recent studies found that Tim-1 is expressed on mast cells. Tim-1 crosslinking by its ligand Tim-4 enhanced secretion of pro-inflammatory cytokines in IgE and Ag-activated bone marrow-derived mast cells (BMMCs). However, the mechanism(s) by which Tim-1 modulates mast cell function and how Tim-1 activity may be altered by antibody treatment is unknown. We hypothesize that Tim-1 engagement provides a co-stimulatory signal to enhance mast cell degranulation and mediator release in allergic inflammation. We found that Tim-1 requires a tyrosine phosphorylation motif in its cytoplasmic tail to co-stimulate NF-AT/ AP1, NF-κB, and IL-6 promoter transcriptional activation as well as IL-6 cytokine secretion. Furthermore, IgE-Ag and Tim-1 costimulation of BMMCs using a panel of Tim-1 antibodies and its ligand Tim-4 demonstrate that IL-6 and TNF-alpha secretion can be modulated by activity of agonistic and blocking Tim-1 antibodies. These studies suggest that Tim-1 may serve as an important modulator of mast cell effector functions in atopic diseases.

Ebola virus (EBOV) is a member of the Filoviridae family of highly pathogenic viruses that cause severe hemorrhagic fever and is the causative agent of the 2014 West Africa outbreak. Currently, there are no approved filovirus vaccines or treatments to combat these sporadic and deadly epidemics. One target for EBOV antiviral therapy is to block viral entry into host cells. Recently, phosphatidylserine (PtdSer) receptors, primarily known for their involvement in the clearance of dying cells, were shown to mediate entry of enveloped viruses including filoviruses. The PtdSer receptors, T-cell immunoglobulin mucin domain-1 (TIM-1) and family member TIM-4, serve as filovirus receptors, significantly enhancing EBOV entry. TIM-dependent virus uptake occurs via apoptotic mimicry by binding to PtdSer on the surface of virions through a conserved PtdSer binding pocket within the amino terminal IgV domain. TIM-4 is expressed on antigen presenting cells (APCs), including macrophages and dendritic cells (DCs), which are critical in early EBOV infection. My studies are the first to define the molecular details of virion/TIM-4 interactions and establish the importance of TIM-4 for EBOV infection of murine resident peritoneal macrophages. In addition, previous work has utilized only in vitro models to establish the importance of the TIM proteins in EBOV entry. My studies are the first to demonstrate the importance of TIM-1 and TIM-4 for in vivo EBOV pathogenesis and to confirm them as relevant targets of future filovirus therapeutics. Macrophage phenotypes can vary greatly depending upon chemokine and cytokine signals from their microenvironment. Historically, macrophages have been classified into two major subgroups: classically activated macrophages (M1) and alternatively activated macrophages (M2). Macrophages are a critical early target of EBOV infection and my work primarily focused on interferon gamma-stimulated (M1) macrophages since this treatment profoundly inhibited EBOV infection of human and murine macrophages. Interferon gamma treatment blocked EBOV replication in macrophages, reducing viral RNA levels in a manner similar to that observed when cultures were treated with the protein synthesis inhibitor, cycloheximide. Microarray studies with interferon gamma-treated human macrophages identified more than 160 interferon-stimulated genes. Ectopic expression of a select group of these genes inhibited EBOV infection. These studies provide new potential avenues for antiviral targeting as these genes that have not previously appreciated to inhibit infection of negative strand RNA viruses including EBOV. In addition and most exciting, using MA-EBOV, we found that murine interferon gamma, when administered either 24 hours before or after infection, protects lethally challenged mice and significantly reduces morbidity. Our findings suggest that interferon gamma, an FDA-approved drug, may serve as a novel and effective prophylactic or treatment option.

Il reclutamento leucocitario è un importante meccanismo d’immunosorveglianza che permette alle cellule del sistema immunitario di migrare da e verso i tessuti periferici garantendo la corretta attuazione della risposta immunitaria. L’interazione tra leucociti ed endotelio è mediata da selectine, integrine e poteine appartenenti alla superfamiglia della immunoglobuline. Nel processo sono coinvolte anche glicoproteine come le mucine, che fungono da ligandi selectinici. Le selectine giocano un ruolo centrale nel trafficking leucocitario mediando le prima fasi di cattura, tethering, e rolling sulla superficie endoteliale. Le Tims sono una famiglia di glicoproteine in grado d’interagire con diversi ligandi. La loro struttura, e in particolare quella di Tim-1, è simile a quella di MADCAM-1(mucin mucosal addressin cell adhesion molecule 1 ), una classica molecola d’adesione coinviolta nel reclutamento leucocitario in grado di legare sia integrine che selectine. Inoltre il dominio mucinico di Tim-1 esibisce moltissimi siti di N e O glicosilazione presenti anche nel dominio mucinico di PSGL-1 (P-selectin glycoprotein ligand 1 ), il ligando selectinico magggiormente caratterizzato. Tutte queste informazioni strutturali ci hanno fatto ipotizzare un ruolo per Tim-1 nel mediare il reclutamento leucocitario sul sito di infiammazione in quanto molecole altamente glicosilate come le mucine, e con le suddette caratteristiche strutturali, sono tipicamente coinvolte in questo processo. Più specificatamente abbiamo cercato di comprendere se Tim-1 sia in grado di legare le selectine e quindi mediare il reclutamento di leucociti sull’endotelio in una maniera selectina-dipendente. In questo lavoro dimostriamo che Tim-1 è un nuovo ligando selectinico. Tim-1 è infatti in grado di legare P-selectin in una maniera calcio dipendente in vitro. Successivamente abbiamo dimostrato l’importanza di Tim-1 nel mediare tethering e rolling di cellule Th1 e Th17 sotto flusso in vitro: cellule mutanti, prive del dominio mucinico di Tim-1, esibiscono una forte riduzione nella capacità di tethering e rolling su P-selectin. Successivamente, per valutare l’importanza del legame Tim-1 - P-selectin anche in vivo abbiamo eseguito esperimenti di microscopia intravitale in venule mesenteriche murine attivate con trombina, ottenendo un modello d’infiammazione P-selectin dipendente. Anche in questo modello la mancanza del dominio mucinico di Tim-1 incide fortemente nella capacità di tethering e rolling di cellule Th1 e Th17. Successivamente abbiamo utilizzato un modello murino di CHS (contact hypersensitivity) per valutare un possible ruolo fisiologico del legame Tim-1 - P-selectin in vivo nel reclutamento leucocitario durante la risposta infiammatoria. La mancanza di Tim-1 in questo modello infiammatorio si traduce in una minor capacità migratoria di celluel T al sito d’infiammazione. Infine abbiamo dimostrato l’importanza di Tim-1 nel mediare reclutamento di cellue Th1 e Th17 nel sistema nervoso centrale. Esperimenti di microscopia intravitale nelle venule piali del cervello hanno dimostrato che cellule Th1 e Th17 prive del dominio mucinico di Tim-1 interagiscono meno con l’endotelio cerebrale infiammato. Le venule piali sono inoltre un punto d’accesso molto importante per le cellule T durante le fasi iniziali di sviluppo dell’encefalite sperimentale autoimmune; il modello murino di sclerosi muplitpla. Abbiamo quindi investigato il coinvolgimento di Tim-1 nello sviluppo di questo modello. La mancanza del dominio mucinico di Tim-1 risulta in uno sviluppo meno severo della patologia con livelli minori d’infiltrato pro-infiammatorio a livello del parenchima cerebrale. Collettivamente i nostri dati dimostrano che Tim-1 è un nuovo ligando per P-selectin con un ruolo specifico nel mediare il reclutamento leucocitario durante le risposte infiammatorie e l’induzione di patologie autoimmuni.
Leucocyte trafficking is an important mechanism of immune surveillance that enables immune cells to migrate to and from peripheral tissues, providing primary and secondary immune responses as requested. The interaction between leukocytes and the inflamed endothelium are mediated by selectins, integrins, and immunoglobulin (Ig) gene super family proteins. Moreover, other important glycoproteins involved in this process are the mucins, which serve as glycoprotein ligands for selectins. Selectins play a central role in leukocyte trafficking by mediating the first phases of tethering and rolling on vascular surfaces. Tims proteins are a class of mucin able to bind a diverse set of ligands. The structure of Tim proteins, in particular the one of Tim-1 is similar to those of the mucin mucosal addressin cell adhesion molecule (MadCAM)-1, a classical adhesion receptor involved in leukocyte trafficking in the immune system able to bind both selectins and integrins. The mucin domain of Tims protein exhibit several sites of O- and N- glycosilation similar to those observed on P-selectin glycoprotein ligand (PSGL)-1; the most charachterized ligand of selectins. Moreover, it has been shown that the IgV domain of Tim-1, exhibits characteristics of the C-type lectins, as its non-species-specific binding to carbohydrate moieties of several cell types is calcium sensitive and is reduced in cells with defective O- and N-linked carbohydrate synthesis. All these structural observations led us to investigate a potential role for Tim-1 in leukocyte trafficking in inflamed tissues as highly glycosilated molecules like C-type lectins, mucins, integrins and Ig-superfamily members are involved in this process. For this reasons we initially tested the ability of Tim-1 to bind selectin, that are known to interact with highly glycosilated mucin like Tim-1. Here we report that T cell immunoglobulin and mucin domain 1 (TIM-1) is a novel P-selectin ligand. We first reported the ability of both human and murine Tim-1 to bind P-selectin in vitro and under shear stress conditions in a cell free system. We then demonstrated the importance of TIM-1 in mediating tethering and rolling of Th1 and Th17 cells on P-selectin in underflow rolling assays. Cells lacking the mucin domain of Tim-1 displayed a strong reduced ability to interact with P-selectin underflow in vitro. To evaluate the importance of Tim-1 –P-selectin binding in vivo we performed intravital microscopy in thrombin-activated mesenteric venules displaying that Th1 and Th17 cells lacking the TIM-1 mucin domain showed reduced rolling ability in vivo in a P-selectin dependent model of inlammation. Uniquely, the TIM-1 IgV domain was also required for P-selectin binding. To evaluate a potential physiologic role for Tim-1/P-selectin interaction in mediating leukocyte trafficking in vivo during inflammatory responses, we demonstrated that inhibition of TIM-1 reduced T cell recruitment in a contact hypersensivity model (CHS) of inlammation. We then demonstrated the importance of Tim-1 in mediating T cell recruitment in the inflamed brain microcirculation adopting intravital microscopy in brain pial venules. Also in this model we have shown that the lacking of Tim-1 mucin domain resulted in a strong reduced ability of Th1 and Th17 cells to interact with the inflamed endothelium. Finally as brain pial venules are a key entry point for T cells in the early phases of development of EAE (experimental autoimmune encephalomyelitis) we checked the involvement of Tim-1 in this model. We discovered that lack of Tim-1 mucin domain resulted in a less severe development of the pathology correlating with a lower T cell accumulation in the CNS. Collectively our data demonstrate that TIM-1 is a major P-selectin ligand with a specialized role in T cell trafficking during inflammatory responses and the induction of autoimmune disease.

Zika virus (ZIKV) is a member of the Flavivirus family. ZIKV infection ranges from asymptomatic to a mild disease in adults. However, in 2015, ZIKV infection became a public health emergency in the Americas associated with neurological alterations such as Guillain-Barré syndrome (GBS) in adults and congenital zika syndrome (CZS). By blocking type I IFN interferon signaling pathways, ZIKV evades the immune system and infects cells expressing the T cell immunoglobulin mucin domain-1 (TIM-1) and TAM (Tyro3, AXL, and Mer) receptors, such as neural progenitor cells. Moreover, ZIKV seems to orchestrate a process of astrocytic hypoxia that leads to the production of reactive oxygen species (ROS), mitochondrial DNA (mtDNA) fragmentation, and apoptosis. In recent decades, the active participation of mitochondria in the immuno-inflammatory response has been reported in several pathologies. In this context, mtDNA seems to have an essential role in triggering the innate immune response by activating inflammasomes, activating the cyclic GMP–AMP synthase (cGAS)–stimulator of interferon genes (STING) pathway, and also activating toll-like receptors that lead to IFN production and viral clearance. Here, we present an overview of some mechanisms of inflammatory response present in ZIKV infection, which contributes to mitochondrial dysfunction, mtDNA release, and tissue damage.

The performance characteristics of thermal interface materials (TIMs) are quickly outpacing our ability to measure them using steady-state techniques. In fact, scientists have turned to photothermal techniques like Time-domain Thermoreflectance (TDTR) to measure the impedance to heat flow across TIMs, namely due to their relatively low measurement uncertainties. However, such techniques are costly, require significant sample preparation, only measure local thermal impedances and are not yet equipped to measure thermal resistance as a function of pressure. Instead, it is desirable to maximize the resolution of traditional steady-state equipment for these types of measurements. In this work, we develop a more robust and accurate methodology to determine the temperature difference across the junction of a traditional steady-state apparatus using high accuracy measurements of in-situ TIM thickness in tandem with infrared thermography. This methodology eliminates a significant fraction of the uncertainty associated with the measurement of thermal interface resistance. Importantly, the use of this method improves the accuracy of the measurement device by an order of magnitude at interfacial thermal resistance values on the order of 1·10−6m2·K/W when compared to state-of-the-art, thermal probe-based measurement systems.

The goal of this research was to provide a better understanding of the interface between root-knot nematodes, Meloidogyne spp., and their host in order to develop rational targets for plantibodies and other novel methods of nematode control directed against the nematode surface coat (SC). Specific objectives were: 1. To produce additional monoclonal SC antibodies for use in Objectives 2, 3, and 4 and as candidates for development of plantibodies. 2. To determine the production and distribution of SC proteins during the infection process. 3. To use biochemical and immunological methods to perturbate the root-knot nematode SC in order to identify SC components that will serve as targets for rationally designed plantibodies. 4. To develop SC-mutant nematodes as additional tools for defining the role of the SC during infection. The external cuticular layer of nematodes is the epicuticle. In many nematodes, it is covered by a fuzzy material termed "surface coat" (SC). Since the SC is the outermost layer, it may playa role in the interaction between the nematode and its surroundings during all life stages in soil and during pathogenesis. The SC is composed mainly of proteins, carbohydrates (which can be part of glycoproteins), and lipids. SC proteins and glycoproteins have been labeled and extracted from preparasitic second-stage juveniles and adult females of Meloidogyne and specific antibodies have been raised against surface antigens. Antibodies can be used to gain more information about surface function and to isolate genes encoding for surface antigens. Characterization of surface antigens and their roles in different life-stages may be an important step towards the development of alternative control. Nevertheless, the role of the plant- parasitic nematode's surface in plant-nematode interaction is still not understood. Carbohydrates or carbohydrate-recognition domains (CROs) on the nematode surface may interact with CROs or carbohydrate molecules, on root surfaces or exudates, or be active after the nematode has penetrated into the root. Surface antigens undoubtedly play an important role in interactions with microorganisms that adhere to the nematodes. Polyclonal (PC) and monoclonal (MC) antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes, were used to characterize the surface coat and secreted-excreted products of M. javanica and M. incognita. Some of the MC and PC antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Further characterization, in planta, of the epitopes recognized by the antibodies, showed that they were present in the parasitic juvenile stages and that the surface coat is shed during root penetration by the nematode and its migration between root cells. At the molecular level, we have followed two lines of experimentation. The first has been to identify genes encoding surface coat (SC) molecules, and we have isolated and characterized a small family of mucin genes from M. incognita. Our second approach has been to study host genes that respond to the nematode, and in particular, to the SC. Our previous work has identified a large suite of genes expressed in Lycopersicon esculentum giant cells, including the partial cDNA clone DB#131, which encodes a serine/threonine protein kinase. Isolation and predicted translation of the mature cDNA revealed a frame shift mutation in the translated region of nematode sensitive plants. By using primers homologous to conserved region of DB#131 we have identified the orthologues from three (nematode-resistant) Lycopersicon peruvianum strains and found that these plants lacked the mutation.