Ion channels are a widespread class of membrane proteins that help establish and control cell membrane potential by allowing the passive diffusion of inorganic ions with high specificity through cell membrane. They are widely distributed in various cells and tissues, and their normal structure and function are of fundamental importance for all living organisms. The rapid advances in molecular cloning, protein structure analysis, patch clamp recordings and other technologies have greatly promoted the research on the biophysical and molecular properties of ion channels, and made significant progress in the study of the relationship between ion channels and pathophysiology as well. The immune system is made up of immune cells and organs that work together to protect the body and respond to infection and disease. Remarkably, recent basic and clinical research has revealed that ion channels are frequently and abundantly expressed in immune cells and have crucial roles in immune cell development and immune response. This review summarized recent progress in the roles of ion channels in immune cells, including the expression and regulation of ion channels in immune cells, the effects of ion flux mediated by ion channels on lymphocyte development, and functional roles of ion channels in both innate and adaptive immune responses. We also discussed some unresolved and insufficiently addressed issues in the current research, so as to provide an informative reference for better understanding the functional roles of ion channels in the immune system and further elucidation of their function from a physiological and pathological point of view.
Cell Membrane ; Immunity ; physiology ; Ion Channels ; immunology ; Membrane Proteins ; Research ; trends

Objective To explore the clinical characteristics of autoimmune disease with dual seropositive antibodies of leucine-rich glioma inactivated 1(LGI1)and contactin-associated protein 2(Caspr2).Methods The clinical data of seven patients with dual seropositive LGI1 and Caspr2 antibodies who were admitted to the Neurology Department of Peking Union Medical College Hospital from July 2014 to December 2017 were retrospectively analyzed.Results Central,peripheral and autonomic nervous systems were all involved in the seven cases;100%(7/7)presented with insomnia,myokymia,neuropahic pain and hyperhydrosis;71%(5/7)showed memory decline or psychiatric and behavioral symptoms;57%(4/7)had urinary hesitation or constipation;and 43%(3/7)had seizure.Electromyography showed 100%(6/6) of the patients had prolonged afterdischarges following normal M waves and/or abnormal spontaneous firing.Electroencephalography revealed slow waves or basic rhythm slowing in 71%(5/7)of patients.Electrocardiography showed sinus tachycardia,axis deviation,and prolonged QT intervals in 71%(5/7)of patients.One patient died from arrhythmia before immunotherapy.One died from pulmonary infection after immunotherapy.Improvement with immunotherapy was documented in the other five cases.No relapse was noted during the 1-2-year follow-up.Conclusions Autoimmune disease with dual seropositive antibodies of LGI1 and Caspr2 can diffusely affect the central,peripheral,and autonomic nervous systems.The possibility of this disease should be considered in patients with acute and subacute onset of neuropsychiatric symptoms,especially in patients with accompanying insomnia,myokymia,and hyperhydrosis.
Autoantibodies ; blood ; Autoimmune Diseases ; immunology ; Humans ; Membrane Proteins ; immunology ; Nerve Tissue Proteins ; immunology ; Proteins ; immunology ; Retrospective Studies

Transforming growth factor (TGF)-β regulates a wide variety of cellular responses, including cell growth arrest, apoptosis, cell differentiation, motility, invasion, extracellular matrix production, tissue fibrosis, angiogenesis, and immune function. Although tumor-suppressive roles of TGF-β have been extensively studied and well-characterized in many cancers, especially at early stages, accumulating evidence has revealed the critical roles of TGF-β as a pro-tumorigenic factor in various types of cancer. This review will focus on recent findings regarding epithelial-mesenchymal transition (EMT) induced by TGF-β, in relation to crosstalk with some other signaling pathways, and the roles of TGF-β in lung and pancreatic cancers, in which TGF-β has been shown to be involved in cancer progression. Recent findings also strongly suggested that targeting TGF-β signaling using specific inhibitors may be useful for the treatment of some cancers. TGF-β plays a pivotal role in the differentiation and function of regulatory T cells (Tregs). TGF-β is produced as latent high molecular weight complexes, and the latent TGF-β complex expressed on the surface of Tregs contains glycoprotein A repetitions predominant (GARP, also known as leucine-rich repeat containing 32 or LRRC32). Inhibition of the TGF-β activities through regulation of the latent TGF-β complex activation will be discussed.
Drug Discovery ; Humans ; Lung Neoplasms ; drug therapy ; immunology ; metabolism ; Membrane Proteins ; metabolism ; Pancreatic Neoplasms ; drug therapy ; immunology ; metabolism ; Signal Transduction ; drug effects ; physiology ; T-Lymphocytes, Regulatory ; metabolism ; Transforming Growth Factor beta ; antagonists & inhibitors ; immunology ; metabolism

Acinetobacter baumannii (A. Baumannii) is an emerging opportunistic pathogen responsible for hospital-acquired infections, and which now constitutes a sufficiently serious threat to public health to necessitate the development of an effective vaccine. In this study, a recombinant fused protein named OmpK/Omp22 and two individual proteins OmpK and Omp22 were obtained using recombinant expression and Ni-affinity purification. Groups of BALB/c mice were immunized with these proteins and challenged with a clinically isolated strain of A. baumannii. The bacterial load in the blood, pathological changes in the lung tissue and survival rates after challenge were evaluated. Mice immunized with OmpK/Omp22 fused protein provided significantly greater protection against A. baumannii challenge than those immunized with either of the two proteins individually. The results provide novel clues for future design of vaccines against A. baumannii.
Acinetobacter Infections ; pathology ; prevention & control ; Acinetobacter baumannii ; genetics ; immunology ; Animals ; Antibodies, Bacterial ; blood ; Bacterial Load ; Bacterial Outer Membrane Proteins ; genetics ; immunology ; Bacterial Vaccines ; immunology ; Disease Models, Animal ; Female ; Mice, Inbred BALB C ; Pneumonia, Bacterial ; pathology ; prevention & control ; Recombinant Fusion Proteins ; genetics ; immunology

Leukocyte differentiation antigens (LDAs) play important roles in the immune system, by serving as surface markers and participating in multiple biological activities, such as recognizing pathogens, mediating membrane signals, interacting with other cells or systems, and regulating cell differentiation and activation. Data mining is a powerful tool used to identify novel LDAs from whole genome. LRRC25 (leucine rich repeat-containing 25) was predicted to have a role in the function of myeloid cells by a large-scale "omics" data analysis. Further experimental validation showed that LRRC25 is highly expressed in primary myeloid cells, such as granulocytes and monocytes, and lowly/intermediately expressed in B cells, but not in T cells and almost all NK cells. It was down-regulated in multiple acute myeloid leukemia (AML) cell lines and bone marrow cells of AML patients and up-regulated after all-trans retinoic acid (ATRA)-mediated granulocytic differentiation in AML cell lines and acute promyelocytic leukemia (APL; AML-M3, FAB classification) cells. Localization analysis showed that LRRC25 is a type I transmembrane molecule. Although ectopic LRRC25 did not promote spontaneous differentiation of NB4 cells, knockdown of LRRC25 by siRNA or shRNA and knockout of LRRC25 by the CRISPR-Cas9 system attenuated ATRA-induced terminal granulocytic differentiation, and restoration of LRRC25 in knockout cells could rescue ATRA-induced granulocytic differentiation. Therefore, LRRC25, a potential leukocyte differentiation antigen, is a key regulator of ATRA-induced granulocytic differentiation.
Antigens, Differentiation ; immunology ; metabolism ; Cell Differentiation ; drug effects ; Cell Line, Tumor ; Granulocytes ; cytology ; drug effects ; immunology ; metabolism ; Humans ; Leukocytes ; cytology ; drug effects ; immunology ; metabolism ; Membrane Proteins ; antagonists & inhibitors ; immunology ; metabolism ; RNA, Small Interfering ; pharmacology ; Tretinoin ; pharmacology

Entero virus 71 (EV71) causes hand, foot, and mouth disease (HFMD) and occasionally leads to severe neurological complications and even death. Scavenger receptor class B member 2 (SCARB2) is a functional receptor for EV71, that mediates viral attachment, internalization, and uncoating. However, the exact binding site of EV71 on SCARB2 is unknown. In this study, we generated a monoclonal antibody (mAb) that binds to human but not mouse SCARB2. It is named JL2, and it can effectively inhibit EV71 infection of target cells. Using a set of chimeras of human and mouse SCARB2, we identified that the region containing residues 77-113 of human SCARB2 contributes significantly to JL2 binding. The structure of the SCARB2-JL2 complex revealed that JL2 binds to the apical region of SCARB2 involving α-helices 2, 5, and 14. Our results provide new insights into the potential binding sites for EV71 on SCARB2 and the molecular mechanism of EV71 entry.
Amino Acid Sequence ; Animals ; Antibodies, Monoclonal ; chemistry ; genetics ; metabolism ; Binding Sites ; Cell Line ; Crystallography, X-Ray ; Enterovirus A, Human ; drug effects ; genetics ; growth & development ; immunology ; Fibroblasts ; drug effects ; virology ; Gene Expression ; HEK293 Cells ; Humans ; Immunoglobulin Fab Fragments ; chemistry ; genetics ; metabolism ; Lysosome-Associated Membrane Glycoproteins ; chemistry ; genetics ; immunology ; Mice ; Models, Molecular ; Protein Binding ; Protein Conformation, alpha-Helical ; Protein Conformation, beta-Strand ; Protein Interaction Domains and Motifs ; Receptors, Scavenger ; chemistry ; genetics ; immunology ; Receptors, Virus ; chemistry ; genetics ; immunology ; Recombinant Fusion Proteins ; chemistry ; genetics ; immunology ; Sequence Alignment ; Sequence Homology, Amino Acid ; Sf9 Cells ; Spodoptera ; Thermodynamics

Interferon-induced Transmembrane Proteins (IFITMs) were identified through small interference RNA (siRNA) screening method in 1980s. The antiviral properties of the IFITMs were firstly discovered in 1996. Recently, its antiviral effect and mechanism have become a research hotspot. Many studies have shown that IFITM can inhibit the replication of multiple pathogenic viruses, including influenza A virus (IAV), Human Immunodeficiency Virus (HIV-1), hepatitis C virus (HCV), Ebola virus (EBOV), West Nile virus and so on. IFITMs inhibit the replication of virus in the early stage of the viral life cycle, which occurred before the release of viral genomes into the cytosol. Recent studies indicate that IFITM proteins could block viral replication by mediate viral membrane fusion. However, the mechanism is still under investigation. Here we review the discovery and characterization of the IFITM proteins, elucidate their antiviral activities and the potential mechanisms.
Animals ; Humans ; Interferons ; genetics ; immunology ; Membrane Proteins ; genetics ; immunology ; Virus Diseases ; genetics ; immunology ; virology ; Viruses ; genetics ; immunology

OBJECTIVEChlamydia psittaci is an avian respiratory pathogen and zoonotic agent. The wide prevalence of C. psittaci poses a threat to the poultry industry and its employees. However, few commercial kits are available for detecting avian antibodies excluding the in-house ELISA kit. In this study, we developed a novel ELISA kit for detecting antibodies against C. psittaci based on the N-terminal fragment of polymorphic outer membrane protein D (PmpD-N) as the coating antigen.

METHODSThe antigen concentrations, primary antibody, and cut-off value were determined and optimized. The ELISA, designated PmpD-N ELISA, was assessed for sensitivity, specificity, and concordance using sera samples from 48 experimentally infected and 168 uninfected SPF chickens.

RESULTSThe sensitivity and specificity of PmpD-N ELISA were 97.9%, 100%, respectively, while the concordance was 98.1% as compared to that of MOMP-ELISA. No cross-reaction with positive sera for other avian pathogens was found. Using PmpD-N ELISA, 799/836 clinical samples were positive, including 93.0% and 98.1% positivity in layers and broilers, respectively.

CONCLUSIONThese data indicate that indirect ELISA with PmpD-N as the antigen candidate is a promising approach for the surveillance of C. psittaci infection.

Animals ; Bacterial Proteins ; analysis ; Chickens ; Chlamydophila psittaci ; genetics ; immunology ; isolation & purification ; Enzyme-Linked Immunosorbent Assay ; veterinary ; Membrane Proteins ; analysis ; Poultry Diseases ; diagnosis ; microbiology ; Psittacosis ; diagnosis ; microbiology ; veterinary ; Sensitivity and Specificity

OBJECTIVETo investigate the effects of inhibiting TIM-4 function in Kupffer cells (KCs) on liver graft rejection in mice and explore the underlying mechanism.

METHODSMouse models of orthotopic liver transplantation were treated with a control mAb group and TIM-4 mAb. The activated KCs were assayed with immunohistochemistry after operation. The expression of TIM-4 in KCs were assayed with Western blotting and RT-PCR and the levels of AST, ALT, TBIL, TNF-α, IFN-γ and CCL2 were assayed detected. The expression of TIM-4 in KCs was observed with laser confocal microscopy. HE staining was used to observe the microstructure of the liver tissues, and the number of CD25Foxp3T cells was determined using with flow cytometry; the proteins levels of p-P65and p-P38 were assayed with Western blotting. The donor mice were treated with clodronate liposomes to destroy the KCs in the liver before transplantation, and the liver grafts were examined for graft rejection.

RESULTSThe number of activated KCs in the liver graft increased progressively over time. Compared with the sham-operated group, the liver graft showed significantly increased TIM-4 protein and mRNA levels at 1, 3, and 7 days after transplantation (P<0.05) and increased levels of AST, ALT, TBIL, TNF-α, IFN-γ and CCL2 at 7 days (P<0.05). The graft in TIM-4 mAb group showed mild pathological changes with a mean RAI score of 2.67∓0.75, which was significantly lower than that in control mAb group (P<0.05). The mean survival time of the recipient mice was 53.8∓6.4 days in TIM-4 mAb group, significantly longer than that in the control mAB group (14.5∓2.9 days, P<0.05). Donor treatment with clodronate liposomes resulted in comparable RAI scores in TIM-4 mAb and control mAb groups (8.01∓0.64 vs 7.93∓0.56, P>0.05). The protein levels of p-P65 and p-P38 in TIM-4 mAb group were significantly lower than those in control mAb group (P<0.05), and CD25Foxp3T cells in the liver graft increased significantly in TIM-4 mAb group.

CONCLUSIONInhibition of TIM-4 function in KCs reduces the production of inflammatory factors after liver transplantation possibly by inhibiting the NF-κB and MAPK signaling pathways and promoting the proliferation of Foxp3Treg cells to induce allograft tolerance.

Animals ; Antibodies, Monoclonal ; pharmacology ; Graft Rejection ; Immunohistochemistry ; Kupffer Cells ; drug effects ; metabolism ; Liver ; surgery ; Liver Transplantation ; Male ; Membrane Proteins ; antagonists & inhibitors ; Mice ; NF-kappa B ; metabolism ; T-Lymphocytes, Regulatory ; immunology

The host takes use of pattern recognition receptors (PRRs) to defend against pathogen invasion or cellular damage. Among microorganism-associated molecular patterns detected by host PRRs, nucleic acids derived from bacteria or viruses are tightly supervised, providing a fundamental mechanism of host defense. Pathogenic DNAs are supposed to be detected by DNA sensors that induce the activation of NFκB or TBK1-IRF3 pathway. DNA sensor cGAS is widely expressed in innate immune cells and is a key sensor of invading DNAs in several cell types. cGAS binds to DNA, followed by a conformational change that allows the synthesis of cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) from adenosine triphosphate and guanosine triphosphate. cGAMP is a strong activator of STING that can activate IRF3 and subsequent type I interferon production. Here we describe recent progresses in DNA sensors especially cGAS in the innate immune responses against pathogenic DNAs.
DNA, Bacterial ; immunology ; metabolism ; DNA, Viral ; immunology ; metabolism ; Gene Expression Regulation ; Host-Pathogen Interactions ; Humans ; Immunity, Innate ; Interferon Regulatory Factor-3 ; genetics ; immunology ; Interferon Type I ; biosynthesis ; immunology ; Membrane Proteins ; genetics ; immunology ; Models, Molecular ; NF-kappa B ; genetics ; immunology ; Nucleotides, Cyclic ; biosynthesis ; immunology ; Nucleotidyltransferases ; genetics ; immunology ; Protein Binding ; Protein-Serine-Threonine Kinases ; genetics ; immunology ; Signal Transduction