Member Of Ig Superfamily Research Articles

A trans-synaptic IgLON adhesion molecular complex directly contacts and clusters a nicotinic receptor.

The localization and clustering of neurotransmitter receptors at appropriate postsynaptic sites is a key step in the control of synaptic transmission. Here, we identify a novel paradigm for the synaptic localization of an ionotropic acetylcholine receptor (AChR) based on the direct interaction of its extracellular domain with a cell adhesion molecule of the IgLON family. Our results show that RIG-5 and ZIG-8, which encode the sole IgLONs in C. elegans, are tethered in the pre- and postsynaptic membranes, respectively, and interact in vivo through their first immunoglobulin-like (Ig) domains. In addition, ZIG-8 traps ACR-16 via a direct cis- interaction between the ZIG-8 Ig2 domain and the base of the large extracellular AChR domain. Such mechanism has never been reported, but all these molecules are conserved during evolution. Similar interactions may directly couple Ig superfamily adhesion molecules and members of the large family of Cys-loop ionotropic receptors, including AChRs, in the mammalian nervous system, and may be relevant in the context of IgLON-associated brain diseases.

Proximity-Based Labeling Identifies MHC Class II and CD37 as B Cell Receptor-Proximal Proteins with Immunological Functions.

The BCR allows for Ag-driven B cell activation and subsequent Ag endocytosis, processing, and presentation to recruit T cell help. Core drivers of BCR signaling and endocytosis are motifs within the receptor's cytoplasmic tail (primarily CD79). However, BCR function can be tuned by other proximal cellular elements, such as CD20 and membrane lipid microdomains. To identify additional proteins that could modulate BCR function, we used a proximity-based biotinylation technique paired with mass spectrometry to identify molecular neighbors of the murine IgM BCR. Those neighbors include MHC class II molecules, integrins, various transporters, and membrane microdomain proteins. Class II molecules, some of which are invariant chain-associated nascent class II, are a readily detected BCR neighbor. This finding is consistent with reports of BCR-class II association within intracellular compartments. The BCR is also in close proximity to multiple proteins involved in the formation of membrane microdomains, including CD37, raftlin, and Ig superfamily member 8. Known defects in T cell-dependent humoral immunity in CD37 knockout mice suggest a role for CD37 in BCR function. In line with this notion, CRISPR-based knockout of CD37 expression in a B cell line heightens BCR signaling, slows BCR endocytosis, and tempers formation of peptide-class II complexes. These results indicate that BCR molecular neighbors can impact membrane-mediated BCR functions. Overall, a proximity-based labeling technique allowed for identification of multiple previously unknown BCR molecular neighbors, including the tetraspanin protein CD37, which can modulate BCR function.

Immune activation of the p75 neurotrophin receptor: implications in neuroinflammation.

Despite structural similarity with other tumor necrosis factor receptor superfamily (TNFRSF) members, the p75 neurotrophin receptor (p75NTR, TNFR16) mediates pleiotropic biological functions not shared with other TNFRs. The high level of p75NTR expression in the nervous system instead of immune cells, its utilization of co-receptors, and its interaction with soluble dimeric, rather than soluble or cell-tethered trimeric ligands are all characteristics which distinguish it from most other TNFRs. Here, we compare these attributes to other members of the TNFR superfamily. In addition, we describe the recent evolutionary adaptation in B7-1 (CD80), an immunoglobulin (Ig) superfamily member, which allows engagement to neuronally-expressed p75NTR. B7-1-mediated binding to p75NTR occurs in humans and other primates, but not lower mammals due to specific sequence changes that evolved recently in primate B7-1. This discovery highlights an additional mechanism by which p75NTR can respond to inflammatory cues and trigger synaptic elimination in the brain through engagement of B7-1, which was considered to be immune-restricted. These observations suggest p75NTR does share commonality with other immune co-modulatory TNFR family members, by responding to immunoregulatory cues. The evolution of primate B7-1 to bind and elicit p75NTR-mediated effects on neuronal morphology and function are discussed in relationship to immune-driven modulation of synaptic actions during injury or inflammation.

Immunoglobulin superfamily member 3 is required for the vagal neural crest cell migration and enteric neuronal network organization

The immunoglobulin (Ig) superfamily members are involved in cell adhesion and migration, complex multistep processes that play critical roles in embryogenesis, wound healing, tissue formation, and many other processes, but their specific functions during embryonic development remain unclear. Here, we have studied the function of the immunoglobulin superfamily member 3 (IGSF3) by generating an Igsf3 knockout (KO) mouse model with CRISPR/Cas9-mediated genome engineering. By combining RNA and protein detection methodology, we show that during development, IGSF3 localizes to the neural crest and a subset of its derivatives, suggesting a role in normal embryonic and early postnatal development. Indeed, inactivation of Igsf3 impairs the ability of the vagal neural crest cells to migrate and normally innervate the intestine. The small intestine of Igsf3 KO mice shows reduced thickness of the muscularis externa and diminished number of enteric neurons. Also, misalignment of neurons and smooth muscle cells in the developing intestinal villi is detected. Taken together, our results suggest that IGSF3 functions contribute to the formation of the enteric nervous system. Given the essential role of the enteric nervous system in maintaining normal gastrointestinal function, our study adds to the pool of information required for further understanding the mechanisms of gut innervation and etiology behind bowel motility disorders.

Structure guided engineering of selective HVEM mutants reveal distinct functions binding to LIGHT and BTLA/CD160

Abstract HVEM is a TNF (tumor necrosis factor) receptor contributing to a broad range of immune functions involving diverse cell types. It interacts with a TNF ligand, LIGHT, and immunoglobulin (Ig) superfamily members BTLA and CD160. Assessing the functional impact of HVEM binding to specific ligands in different settings has been complicated by the multiple interactions of HVEM and HVEM binding partners. To dissect the molecular basis for multiple functions, we determined crystal structures that reveal the distinct HVEM surfaces that engage LIGHT or BTLA/CD160, including the human HVEM–LIGHT–CD160 ternary complex, with HVEM interacting simultaneously with both binding partners. Based on these structures, we generated mouse HVEM mutants that selectively recognized either the TNF or Ig ligands in vitro. Knockin mice expressing these muteins maintain expression of all the proteins in the HVEM network, yet they demonstrate selective functions for LIGHT in the clearance of bacteria in the intestine and for the Ig ligands in the amelioration of liver inflammation. Supported grants from NIH (S10 OD020068, P30CA023100, P30 DK120515, S10RR027366, U01 AI125955, P01 DK46763), U.S. Department of Energy (DE-AC02-98CH10886, DE-AC02-06CH11357), National Center for Research Resources (P41RR012408), National Institute of General Medical Sciences (P41GM103473), Albert Einstein Cancer Center (P30CA013330), Eli Lilly Company, Albert Einstein Macromolecular Therapeutics Development Facility, Price Family Foundation, Albert Einstein Center for Experimental Therapeutics, Pamela and Edward S. Pantzer, and Academia Sinica, Taiwan.

NFI transcriptionally represses CDON and is required for SH-SY5Y cell survival

Nuclear Factor One (NFI) family of transcription factors regulate proliferation and multiple aspects of differentiation, playing analogous roles in embryonic development and various types of cancer. While all NFI family members are expressed in the developing brain and are involved in progression of brain cancers, their role in neuroblastoma has not been studied. Here we show that NFIB is required for the survival and proliferation of SH-SY5Y neuroblastoma cells, assessed by viability and colony formation assays. Cdon, an Ig superfamily member, is a SHH dependence receptor that acts as a tumor suppressor in neuroblastoma. In the absence of NFI, Cdon is upregulated in the developing mouse brain, however the mechanisms by which its transcription is regulated remains unknown. We report CDON as a downstream target of NFIs in SH-SY5Y cells. There are three putative NFI binding sites within the one kb CDON promoter, two of which are occupied by NFIs in SH-SY5Y cells and human neural stem cells. In dual-luciferase assays, Nfib directly represses CDON proximal promoter activity. Moreover, silencing NFIB leads to upregulation of CDON in SH-SY5Y cells, however, decreased cell proliferation in NFIB silenced cells could not be rescued by concomitantly silencing CDON, suggesting other molecular players are involved. For instance, p21, an NFI target in glioblastoma and breast cancer cells, is also upregulated upon NFIB knock-down. We propose that NFIB is indispensable for SH-SY5Y cells which may involve regulation of apoptosis inducer proteins CDON and p21.

The Immunoglobulin Superfamily Members syg-2 and syg-1 Regulate Neurite Development in C. elegans.

Neurons form elaborate networks by guiding axons and dendrites to appropriate destinations. Neurites require information about the relative body axes during the initial projection from the cell body, and failure to receive or interpret those cues correctly can result in outgrowth errors. We identified a mutation in the Ig superfamily member syg-2 in a screen for animals with anterior/posterior (A/P) axon guidance defects. We found that syg-2 and its cognate Ig family member syg-1 appear to function in a linear genetic pathway to control the outgrowth of GABAergic axons. We determined that this pathway works in parallel to Wnt signaling. Specifically, mutations in syg-2 or syg-1 selectively affected the embryonically derived Dorsal D-type (DD) GABAergic neurons. We found no evidence that these mutations affected the Ventral D-type neurons (VD) that form later, during the first larval stage. In addition, mutations in syg-1 or syg-2 could result in the DD neurons forming multiple processes, becoming bipolar, rather than the expected pseudounipolar morphology. Given SYG-2′s essential function in synaptogenesis of the hermaphrodite-specific neurons (HSNs), we also examined DD neuron synapses in syg-2 mutants. We found syg-2 mutants had a decreased number of synapses formed, but synaptic morphology was largely normal. These results provide further evidence that the GABAergic motorneurons use multiple guidance pathways during development.

HVEM structures and mutants reveal distinct functions of binding to LIGHT and BTLA/CD160.

HVEM is a TNF (tumor necrosis factor) receptor contributing to a broad range of immune functions involving diverse cell types. It interacts with a TNF ligand, LIGHT, and immunoglobulin (Ig) superfamily members BTLA and CD160. Assessing the functional impact of HVEM binding to specific ligands in different settings has been complicated by the multiple interactions of HVEM and HVEM binding partners. To dissect the molecular basis for multiple functions, we determined crystal structures that reveal the distinct HVEM surfaces that engage LIGHT or BTLA/CD160, including the human HVEM-LIGHT-CD160 ternary complex, with HVEM interacting simultaneously with both binding partners. Based on these structures, we generated mouse HVEM mutants that selectively recognized either the TNF or Ig ligands in vitro. Knockin mice expressing these muteins maintain expression of all the proteins in the HVEM network, yet they demonstrate selective functions for LIGHT in the clearance of bacteria in the intestine and for the Ig ligands in the amelioration of liver inflammation.

Allosteric regulation of binding specificity of HVEM for CD160 and BTLA ligands upon G89F mutation.

Molecular interactions mediated by engagement of the Herpes virus entry mediator (HVEM) with members of TNF and Ig superfamily generate distinct signals in T cell activation pathways that modulate inflammatory and inhibitory responses. HVEM interacts with CD160 and B and T lymphocyte attenuator (BTLA), both members of the immunoglobulin (Ig) superfamily, which share a common binding site that is unique from that of LIGHT, a TNF ligand. BTLA or CD160 engagement with HVEM deliver inhibitory or stimulatory signals to the host immune response in a context dependent fashion, whereas HVEM engagement with LIGHT results in pro-inflammatory responses. We identified a mutation in human HVEM, G89F, which directly interferes with the human LIGHT interaction, but interestingly, also differentially modulates the binding of human BTLA and CD160 via an apparent allosteric mechanism involving recognition surfaces remote from the site of the mutation. Specifically, the G89F mutation enhances binding of CD160, while decreasing that of BTLA to HVEM in cell-based assays. Molecular dynamics simulations for wild-type and G89F mutant HVEM, bound to different sets of ligands, were performed to define the molecular basis of this unexpected allosteric effect. These results were leveraged to design additional human HVEM mutants with altered binding specificities.

IgIT-Mediated Signaling Inhibits the Antimicrobial Immune Response in Oyster Hemocytes.

The long-term evolutionary interaction between the host and symbiotic microbes determines their cooperative relationship. It is well known that the symbiotic microbes have evolved various mechanisms to either benefit or exploit the mammalian host immune system to maintain homeostasis. However, the strategies employed by the symbiotic microbes to overcome host immune responses in invertebrates are still not clear. In the current study, the hemolymph microbes in oyster Crassostrea gigas were found to be able to directly bind an oyster Ig superfamily member (IgSF) (designated as CgIgIT) to inhibit the immune responses of hemocytes. The mRNA transcripts of CgIgIT in hemocytes increased significantly after the stimulation with hemolymph microbes. CgIgIT was found to be located on the hemocyte membrane and it was able to directly bind the hemolymph microbes and polysaccharides via its three Ig domains and recruited the protein tyrosine phosphatase CgSHP2 through its ITIM. The recruited CgSHP2 inhibited the activities of CgERK, CgP38 and CgJNK proteins to reduce the productions of dual oxidase 2 (CgDuox2) and defensin 2 (CgDef2), which eventually protected the hemolymph microbes from CgDuox2/CgDef2-mediated elimination. Collectively, the results suggest that the oyster IgIT-SHP2 signaling pathway can recognize bacteria capable of residing in oyster hemolymph and inhibit innate immune responses, which contributes to the maintenance, colonization, and survival of hemolymph microbes.

Lymph Node Subcapsular Sinus Microenvironment-On-A-ChipModeling Shear Flow Relevant to Lymphatic Metastasis and Immune Cell Homing.

SummaryA lymph node sinus-on-a-chip adhesion microfluidic platform that recapitulates the hydrodynamic microenvironment of the lymph node subcapsular sinus was engineered. This device was used to interrogate the effects of lymph node remodeling on cellular adhesion in fluid flow relevant to lymphatic metastasis. Wall shear stress levels analytically estimated and modeled after quiescent and diseased/inflamed lymph nodes were experimentally recapitulated using a flow-based microfluidic perfusion system to assess the effects of physiological flow fields on human metastatic cancer cell adhesion. Results suggest that both altered fluid flow profiles and presentation of adhesive ligands, which are predicted to manifest within the lymph node subcapsular sinus as a result of inflammation-induced remodeling, and the presence of lymph-borne monocytic cells may synergistically contribute to the dynamic extent of cell adhesion in flow relevant to lymph node invasion by cancer and monocytic immune cells during lymphatic metastasis.

Inhibition of allogeneic islet graft rejection by VISTA-conjugated liposome

The Ig superfamily member V-domain Ig-containing suppressor of T-cell activation (VISTA) is a negative regulator with broad-spectrum activities and has reported that blockade of VISTA or combination with other negative checkpoint receptors sufficiently break tumor tolerance. However, it remains unclear whether VISTA could induce allogeneic T-cell hyporesponsiveness and inhibit allograft rejection. Here we found VISTA treatment significantly inhibited lymphocyte proliferation and activation in allogeneic MLR assay through impairing SYK-VAV pathway. Interestingly, though neither VISTA protein nor VISTA-Fc fusion protein administration exerted satisfactory immunosuppressive effect on allograft survival due to their short half-life in circulation, this problem was solved by conjugating VISTA protein on liposome by biotin-streptavidin system, which markedly prolonged its circulating half-life to 60 h. With islet transplant model, administration of VISTA-conjugated liposome could markedly prolong allograft survival by inhibition of SYK-VAV pathway, thus maintained the normal blood glucose level of recipients during treatment period. The results indicate VISTA is a promising therapeutic target to treat allograft rejection of islet transplantation.

The Splicing Factor RNA-Binding Fox Protein 1 Mediates the Cellular Immune Response in Drosophila melanogaster.

The uptake and destruction of bacteria by phagocytic cells is an essential defense mechanism in metazoans. To identify novel genes involved in the phagocytosis of Staphylococcus aureus, a major human pathogen, we assessed the phagocytic capacity of adult blood cells (hemocytes) of the fruit fly, Drosophila melanogaster, by testing several lines of the Drosophila Genetic Reference Panel. Natural genetic variation in the gene RNA-binding Fox protein 1 (Rbfox1) correlated with low phagocytic capacity in hemocytes, pointing to Rbfox1 as a candidate regulator of phagocytosis. Loss of Rbfox1 resulted in increased expression of the Ig superfamily member Down syndrome adhesion molecule 4 (Dscam4). Silencing of Dscam4 in Rbfox1-depleted blood cells rescued the fly's cellular immune response to S. aureus, indicating that downregulation of Dscam4 by Rbfox1 is critical for S. aureus phagocytosis in Drosophila To our knowledge, this study is the first to demonstrate a link between Rbfox1, Dscam4, and host defense against S. aureus.

Abstract 4046: The different immune evasion mechanisms in human prostate cancer

Abstract Cancer development is associated with a number of genetic and epigenetic alternations. Normally, these alterations are detected by the immune system in a process called immune surveillance, where cancer cell killing is mediated by cytotoxic T lymphocytes (CTL) and natural killer cells (NK cells). Yet, tumor progression and development indicate that cancer cells have acquired mechanisms to avoid immune destruction. Various immune evasion mechanisms have been reported before such as impaired antigen presentation and activation of CTL and NK cells, immunosuppression, and induction of tolerance. Although current treatment methods are shifting towards more targeted strategies in prostate cancer, such as immunotherapy, a better understanding of the cancer-immune interactions and immune evasion mechanisms is yet to be established. More immunotherapies are being developed and approved by the FDA for treating cancer. In prostate cancer, Sipuleucel-T, an autologous cellular immunotherapy, was approved by FDA for the treatment of asymptomatic or minimally symptomatic metastatic castrate resistant (hormone refractory) prostate cancer. Intensive investigation on other immunotherapies is ongoing in prostate cancer. These include blockade of negative checkpoint regulators (PD-1, CTLA4) and Ig superfamily member V-domain Ig-containing suppressor of T-cell activation (VISTA), chimeric antigen receptor-modified T (CAR-T) cells against prostate lineage-unique proteins (PLUPs), and monoclonal antibodies targeting immunoinhibitory molecules. However, the optimal choice of treatment for a prostate cancer patient needs to target their specific mechanisms of immune evasion, which are poorly studied. In this study, we will use The Cancer Genome Atlas RNA-seq data to check for immune evasion gene expression in prostate cancer patients to identify at the different mechanisms by which cancer avoids immune destruction. We will use a sequential biclustering algorithm developed by our group, to group prostate cancer patients based on their similarities in immune evasion gene expression. A similar unpublished work was done by our group on breast cancer where we identified 7 different groups of patients, each with different mechanisms or combination of evasion mechanism. We also showed that triple negative breast cancer can be immunogenic and non-immunogenic. This group-based identification of evasion mechanisms will not only provide a better understanding of the different immune evasion mechanisms in prostate cancer, but will also shed light on potential combinations of mechanism. This in turn, will help guide the choice of single and combined immunotherapeutic approches. Citation Format: Mayassa J. Bou-Dargham, Yuhang Liu, Qing-Xiang Amy Sang, Jinfeng Zhang. The different immune evasion mechanisms in human prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4046.

Expression of Vascular Cell Adhesion Molecule 1 (VCAM-1) in the Mammary Lymph Nodes of Cows with Subclinical Mastitis.

IntroductionVascular cell adhesion molecule 1 (VCAM-1) is a member of Ig superfamily. The aim of this study was to prepare highly specific polyclonal antibodies against bovine VCAM-1 and to evaluate the expression of VCAM-1 in the mammary lymph nodes of cows with subclinical mastitis.Material and MethodsThe VCAM-1 gene was cloned from bovine Peyer’s patches and inserted into the pGEX-4T-1 and pET-28a vectors. The recombinant plasmids pGEX-4T-1/VCAM-1 and pET-28a/VCAM-1 were transferred into Escherichia coli BL21 and the recombinant strains were induced by isopropyl-D-thiogalactoside to produce fusion proteins tagged with polyhistidine (His) and glutathione S-transferase (GST), respectively. The expressed fusion proteins His-VCAM-1 and GST-VCAM-1 were identified by SDS-PAGE and Western blot. His-VCAM-1 protein was used as an antigen to immunise Wistar rats and polyclonal antibody serum against VCAM-1 was obtained.ResultsThe serum titre tested by indirect ELISA was 128,000 using GST-VCAM-1 as the well coating antigen. Western blots indicated that the antibody recognised recombinant VCAM-1 protein as well as endogenous VCAM-1. In addition, using qPCR and Western blot, VCAM-1 mRNA and protein expression levels were measured in dairy cows with subclinical mastitis. It was demonstrated that VCAM-1 levels in the mammary lymph nodes of the cows were significantly higher than those from healthy controls (P < 0.05).ConclusionThese results are to our knowledge the first report that VCAM-1 expression in the mammary lymph nodes is elevated in dairy cows with subclinical mastitis.

HVEM-BTLA interactions stimulate lung innate immunity following S. pneumoniae infection.

Abstract Streptococcus pneumoniae (S. pneumoniae) is the leading cause of bacterial pneumonia in children and the elderly and it kills close to half a million children under 5 years old worldwide every year. Recent reports indicate that epithelial cells act not only as a physical barrier to pathogen invasion, but also as an extension of the immune system to prevent infection or eliminate pathogen. The herpes virus entry mediator (HVEM) is a member of the tumor necrosis factor (TNF) receptor super family. HVEM polymorphisms are a risk factor for several inflammatory and infectious diseases. Although lymphocytes and myeloid cells express HVEM, our previous data suggested that HVEM expression by epithelial cells was critical for innate immunity in the lung. However, the mechanism of HVEM-mediated host defense against S. pneumoniae is still unknown. To address the issue, we have analyzed mice with a lung epithelial cell-specific deletion of HVEM (Cc10-cre x Hvemfl/fl). We found that Cc10-cre x Hvemfl/fl mice were highly susceptible to S. pneumoniae, with an increased bacterial load by 24h and reduced survival. Mice treated with an antibody that blocks HVEM had a similar outcome, confirming that HVEM expression is required during the infection. HVEM has three ligands: the TNF super family member LIGHT and the Ig super family members BTLA and CD160. We determined that BTLA-deficient mice showed increased bacterial load in the lung and reduced survival, similar to HVEM deficiency. Moreover, CD11c-cre x BTLA fl/fl mice were highly susceptible to S. pneumoniae. Our data show that interaction between BTLA expressed by a CD11c positive myeloid cell type and HVEM expressed by lung epithelial cells leads to a protective innate response in the lung after infection.

Keep Your Friends Close: Cell–Cell Contact and Skeletal Myogenesis

Development of skeletal muscle is a multistage process that includes lineage commitment of multipotent progenitor cells, differentiation and fusion of myoblasts into multinucleated myofibers, and maturation of myofibers into distinct types. Lineage-specific transcriptional regulation lies at the core of this process, but myogenesis is also regulated by extracellular cues. Some of these cues are initiated by direct cell-cell contact between muscle precursor cells themselves or between muscle precursors and cells of other lineages. Examples of the latter include interaction of migrating neural crest cells with multipotent muscle progenitor cells, muscle interstitial cells with myoblasts, and neurons with myofibers. Among the signaling factors involved are Notch ligands and receptors, cadherins, Ig superfamily members, and Ephrins and Eph receptors. In this article we describe recent progress in this area and highlight open questions raised by the findings.

Costimulation Blockade in Autoimmunity and Transplantation: The CD28 Pathway.

T cell activation is a complex process that requires multiple cell signaling pathways, including a primary recognition signal and additional costimulatory signals. TCR signaling in the absence of costimulatory signals can lead to an abortive attempt at activation and subsequent anergy. One of the best-characterized costimulatory pathways includes the Ig superfamily members CD28 and CTLA-4 and their ligands CD80 and CD86. The development of the fusion protein CTLA-4-Ig as an experimental and subsequent therapeutic tool is one of the major success stories in modern immunology. Abatacept and belatacept are clinically approved agents for the treatment of rheumatoid arthritis and renal transplantation, respectively. Future interventions may include selective CD28 blockade to block the costimulatory potential of CD28 while exploiting the coinhibitory effects of CTLA-4.

Association of CD147 and Calcium Exporter PMCA4 Uncouples IL-2 Expression from Early TCR Signaling.

The Ig superfamily member CD147 is upregulated following T cell activation and was shown to serve as a negative regulator of T cell proliferation. Thus, Abs targeting CD147 are being tested as new treatment strategies for cancer and autoimmune diseases. How CD147 mediates immunosuppression and whether association with other coreceptor complexes is needed have remained unknown. In the current study, we show that silencing of CD147 in human T cells increases IL-2 production without affecting the TCR proximal signaling components. We mapped the immunosuppressive moieties of CD147 to its transmembrane domain and Ig-like domain II. Using affinity purification combined with mass spectrometry, we determined the domain specificity of CD147 interaction partners and identified the calcium exporter plasma membrane calcium ATPase isoform 4 (PMCA4) as the interaction partner of the immunosuppressive moieties of CD147. CD147 does not control the proper membrane localization of PMCA4, but PMCA4 is essential for the CD147-dependent inhibition of IL-2 expression via a calcium-independent mechanism. In summary, our data show that CD147 interacts via its immunomodulatory domains with PMCA4 to bypass TCR proximal signaling and inhibit IL-2 expression.

Heart morphology in Zucker-obese rat

Obesity represents the central and causal component of the metabolic syndrome (MetS), which is a growing medical challenge in western countries as a result of changes in lifestyle. Obesity is also associated with an increased incidence of arterial hypertension and of cardiovascular disease burden. In animal models of diet-induced obesity, endothelial inflammatory activation, demonstrated by changes in adhesion molecule expression, is one of the earliest manifestation of vascular and cardiac damage. The intercellular adhesion molecule-1 (ICAM-1) is a member of the immunoglobulin (Ig) superfamily present on the surface of several other cell types, including endothelial cells. Adhesion molecules [e.g., ICAM-1, vascular cell adhesion molecule 1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1)] if in contact with an activated endothelium could represent attractive targets for delivery of drugs and imaging probes to vascular pathological sites. The present study was designed to investigate, with morphological, immunochemical and immunohistochemical techniques, changes of heart and coronary arteries in Obese Zucker rats (OZR) compared to the lean Zucker rats (LZRs). The OZRs, with a mutation in leptin receptors, is a model of Type II diabetes mellitus, characterized by the presence of obesity, hyperglycemia, hyperinsulinemia, hyperlipidemia and moderate hypertension similar to MetS. The heart of OZRs of 12, 16 and 20 weeks was processed for microanatomical analysis and ICAM-1, VCAM-1 and PECAM-1 and pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) immunohistochemistry. OZRs at the different age, developed ventricular hypertrophy, characterized by increase size of cardiomyocytes but not fibrosis compared to LZRs. This phenomenon was more evident in 20-weeks-old OZRs. VCAM-1 was more expressed in the coronary arteries compared to other adhesion molecules, and increased in the OZRs of 20-weeks of age. In the same age, IL-6 expression was significantly increased. These results suggest that the obesity leads to heart tissue changes and coronary inflammation. Myocardial vascular inflammation, induced by metabolic comorbidities, could contribute to the development of heart failure. Protective strategies in obesity may be focussed versus body weight loss and countering of metabolic alterations induced by obesity.