Objective To investigate the effects of hyaluronic acid and proteoglycan-linked protein 1 (HAPLN1) secreted by synovial fibroblasts (FLS) on the polarization of macrophages (Mϕ) in rheumatoid arthritis (RA). Methods Human monocytic leukemia cells (THP-1) were differentiated into Mϕ, which were subsequently exposed to recombinant HAPLN1 (rHAPLN1). RA-FLS were transfected separately with HAPLN1 overexpression plasmid (HAPLN1^OE) or small interfering RNA targeting HAPLN1 (si-HAPLN1), and then co-cultured with Mϕ to establish a co-culture model. The viability of Mϕ was assessed using the CCK-8 assay, and the proportions of pro-inflammatory M1-type and anti-inflammatory M2-type Mϕ were analyzed by flow cytometry. Additionally, the expression levels of inflammatory markers, including interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and inducible nitric oxide synthase (iNOS), were quantified using quantitative real-time PCR and Western blot analysis. Results The viability of Mϕ was increased in the rHAPLN1 group compared to the control group. Furthermore, both the M1/Mϕ ratio and inflammatory factor levels were elevated in the rHAPLN1 and HAPLN1^OE groups. In contrast, the si-HAPLN1 group exhibited a decrease in the M1/Mϕ ratio and inflammatory factor expression. Notably, the introduction of rHAPLN1 in rescue experiments further promoted Mϕ polarization towards the M1 phenotype. Conclusion HAPLN1, secreted by RA fibroblast-like synoviocytes (RA-FLS), enhances Mϕ polarization towards the M1 phenotype.
Humans ; Arthritis, Rheumatoid/genetics* ; Macrophages/immunology* ; Fibroblasts/metabolism* ; Phenotype ; Extracellular Matrix Proteins/genetics* ; Proteoglycans/genetics* ; Synovial Membrane/cytology* ; Tumor Necrosis Factor-alpha/genetics* ; Interleukin-1beta/genetics* ; Nitric Oxide Synthase Type II/genetics* ; Cell Differentiation ; Coculture Techniques ; THP-1 Cells

Objective To explore the effect of the knockdown of transmembrane 9 superfamily protein member 2 (TM9SF2) on the replication of vesicular stomatitis virus (VSV), and investigate its role in the mechanism of antiviral innate immunity. Methods Small interfering RNA (siRNA) was used to knock down the TM9SF2 gene in human non-small cell lung cancer A549 cells. The CCK-8 method was used to assess cell proliferation. A VSV-green fluorescent protein (VSV-GFP) infected cell model was established. The plaque assay was used to measure the viral titer in the supernatant. RT-qPCR and Western blotting were employed to quantify the mRNA and protein levels of VSV genome replication in A549 cells following VSV infection, as well as the expression of interferon β (IFN-β) mRNA and interferon regulatory factor 3 (IRF3) protein phosphorylation following polyinosinic-polycytidylic acid (poly(I:C)) stimulation. Results Compared to the negative control, the knockdown of TM9SF2 exhibited a significant effect, with no observed impact on A549 cell proliferation. The VSV-GFP infected A549 cell model was successfully established. After viral stimulation, fluorescence intensity was reduced following TM9SF2 knockdown, and the mRNA and protein levels of VSV were significantly downregulated. The viral titer of VSV was decreased. After poly(I:C) stimulation, TM9SF2 knockdown significantly upregulated the mRNA level of IFN-β and the phosphorylation level of IRF3 protein. Conclusion The knockdown of TM9SF2 inhibits the replication of vesicular stomatitis virus, and positively regulates the type I interferon signaling pathway, thus enhancing the host's antiviral innate immune response.
Humans ; Virus Replication/genetics* ; Signal Transduction ; Membrane Proteins/metabolism* ; A549 Cells ; Vesiculovirus/physiology* ; Interferon-beta/metabolism* ; Interferon Regulatory Factor-3/genetics* ; Interferon Type I/metabolism* ; Vesicular Stomatitis/immunology* ; Gene Knockdown Techniques ; Vesicular stomatitis Indiana virus/physiology* ; RNA, Small Interfering/genetics*

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

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

No abstract available.
Bone Marrow/metabolism/pathology ; DNA Mutational Analysis ; Gene Rearrangement, T-Lymphocyte ; Humans ; Immunophenotyping ; Infant ; Lymphohistiocytosis, Hemophagocytic/*diagnosis ; Male ; Membrane Proteins/chemistry/genetics ; Polymorphism, Single-Stranded Conformational ; Republic of Korea ; T-Lymphocytes/immunology/*metabolism

Amplification of the 16S rRNA gene from a blood sample obtained from a dog in southeastern Brazil was used to confirm a naturally acquired Ehrlichia (E.) canis infection. Following isolation and culturing of the new bacterial strain called Uberlandia, partial sequences of the dsb and p28 genes were obtained. The dsb partial sequence of the novel strain was 100% similar to dsb gene sequences of E. canis obtained from different geographic areas around the world. Conversely, the p28 partial sequence for the E. canis Uberlandia strain differed at several nucleotides from other sequences available in GenBank. To confirm the antigenic profile of the Uberlandia strain, an indirect immunofluorescence assay against E. canis antigens was performed using dog sera collected from two different areas in Brazil (Uberlandia and Sao Paulo). The results suggest that both antigens were able to identify animals seropositive for E. canis in Brazil since these Brazilian strains appear to be highly conserved.
Animals ; Antigens, Bacterial/blood/*diagnostic use ; Bacterial Outer Membrane Proteins/genetics/metabolism ; Bacterial Proteins/*genetics/metabolism ; Base Sequence ; Brazil ; Dog Diseases/diagnosis/*microbiology ; Dogs ; Ehrlichia canis/*genetics/*immunology/isolation & purification ; Ehrlichiosis/diagnosis/microbiology/*veterinary ; Fluorescent Antibody Technique, Indirect/veterinary ; Male ; Molecular Sequence Data ; Polymerase Chain Reaction/veterinary ; RNA, Ribosomal, 16S/genetics/metabolism ; Sequence Alignment/veterinary

Autophagy plays important roles in modulating viral replication and antiviral immune response. Coronavirus infection is associated with the autophagic process, however, little is known about the mechanisms of autophagy induction and its contribution to coronavirus regulation of host innate responses. Here, we show that the membrane-associated papain-like protease PLP2 (PLP2-TM) of coronaviruses acts as a novel autophagy-inducing protein. Intriguingly, PLP2-TM induces incomplete autophagy process by increasing the accumulation of autophagosomes but blocking the fusion of autophagosomes with lysosomes. Furthermore, PLP2-TM interacts with the key autophagy regulators, LC3 and Beclin1, and promotes Beclin1 interaction with STING, the key regulator for antiviral IFN signaling. Finally, knockdown of Beclin1 partially reverses PLP2-TM's inhibitory effect on innate immunity which resulting in decreased coronavirus replication. These results suggested that coronavirus papain-like protease induces incomplete autophagy by interacting with Beclin1, which in turn modulates coronavirus replication and antiviral innate immunity.
Apoptosis Regulatory Proteins ; antagonists & inhibitors ; genetics ; immunology ; Autophagy ; Beclin-1 ; Coronavirus NL63, Human ; genetics ; immunology ; Gene Expression Regulation ; HEK293 Cells ; HeLa Cells ; Host-Pathogen Interactions ; immunology ; Humans ; Immune Evasion ; Immunity, Innate ; Interferon-gamma ; genetics ; immunology ; Lysosomes ; metabolism ; virology ; MCF-7 Cells ; Membrane Fusion ; Membrane Proteins ; antagonists & inhibitors ; genetics ; immunology ; Microtubule-Associated Proteins ; genetics ; immunology ; Papain ; genetics ; immunology ; Phagosomes ; metabolism ; virology ; RNA, Small Interfering ; genetics ; immunology ; Signal Transduction ; Virus Replication

The aim of this study is to construct a SARS-CoV S protein-specific phage displayed antigen library for the epitope characterization of anti-S monoclonal antibodies (mAbs). First, the full-length gene of SARS-S protein was PCR amplified, purified and then digested with DNase I to obtain DNA fragments in the size range of 50-500 bp. The resulting fragments were blunt-end ligated to the modified phage display vector pComb3XSS. The reactions were electrotransformed into XL1-Blue and infected with VCSM13 helper phage. The SARS-CoV S protein-specific phage displayed antigen library was biopanned and screened against two anti-S mAbs, S-M1 and S-M2. The results showed that we successfully constructed the phage displayed antigen library with a size of 5.7 x 10(6). After three-rounds of biopanning, 14 positive phage clones for S-M1 and 15 for S-M2 were respectively identified. Sequence analyses revealed the possible epitopes of two mAbs. Therefore, the S protein-specific phage displayed antigen library provides a crucial platform for the epitope characterization of anti-S antibodies and it is highly valuable for development of SARS vaccines and diagnostics.
Antibodies, Viral ; immunology ; Bacteriophages ; genetics ; metabolism ; Epitopes ; genetics ; immunology ; Humans ; Membrane Glycoproteins ; genetics ; immunology ; Peptide Library ; SARS Virus ; genetics ; immunology ; Severe Acute Respiratory Syndrome ; immunology ; virology ; Spike Glycoprotein, Coronavirus ; Viral Envelope Proteins ; genetics ; immunology

OBJECTIVETo explore the expression and clinical significance of T cell immunoglobulin mucin (TIM)-1, TIM-3 and T cell-specific transcription factors T-bet and GATA-3 in spleen mononuclear cells in patients with primary immune thrombocytopenia (ITP).

METHODSThe spleen samples were obtained from 17 active ITP patients and 10 controls with spleen traumatic rupture. By using real-time quantitative polymerase chain reaction, the mRNA expressions of TIM-3, TIM1, T-bet and GATA-3 were studied in all subjects.

RESULTSTIM-3 mRNA levels of active ITP patients were significantly decreased to (29 ± 16)% of that of control, TIM-1 mRNA levels of active ITP patients increased to (3.20 ± 2.18) folds of that of control, but the difference was not significant. The ratio of TIM-1/ TIM-3 was elevated in active ITP patients. T-bet mRNA levels were up-regulated in ITP patients by (2.82 ± 1.57) folds (P<0.05) and the expression of GATA3 was decreased by 14% folds (P<0.05) compared to controls. The ratio of T-bet/GATA3 were significantly elevated in ITP patients.

CONCLUSIONThe imbalance between TIM-3 and TIM-1 expression might play an important role in pathogenesis of ITP.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Case-Control Studies ; Female ; Flow Cytometry ; GATA3 Transcription Factor ; metabolism ; Hepatitis A Virus Cellular Receptor 1 ; Hepatitis A Virus Cellular Receptor 2 ; Humans ; Male ; Membrane Glycoproteins ; metabolism ; Membrane Proteins ; metabolism ; Middle Aged ; Purpura, Thrombocytopenic, Idiopathic ; immunology ; metabolism ; RNA, Messenger ; genetics ; Receptors, Virus ; metabolism ; Spleen ; metabolism ; Th1 Cells ; immunology ; Th2 Cells ; immunology ; Young Adult

OBJECTIVETo determine expression changes of major outer membrane protein(OMP) antigens of Leptospira interrogans serogroup Icterohaemorrhagiae serovar Lai strain Lai during infection of human macrophages and its mechanism.

METHODSOmpR encoding genes and OmpR-related histidine kinase (HK) encoding gene of L.interrogans strain Lai and their functional domains were predicted using bioinformatics technique. mRNA level changes of the leptospiral major OMP-encoding genes before and after infection of human THP-1 macrophages were detected by real-time fluorescence quantitative RT-PCR. Effects of the OmpR-encoding genes and HK-encoding gene on the expression of leptospiral OMPs during infection were determined by HK-peptide antiserum block assay and closantel inhibitive assays.

RESULTSThe bioinformatics analysis indicated that LB015 and LB333 were referred to OmpR-encoding genes of the spirochete, while LB014 might act as a OmpR-related HK-encoding gene. After the spirochete infecting THP-1 cells, mRNA levels of leptospiral lipL21, lipL32 and lipL41 genes were rapidly and persistently down-regulated (P <0.01), whereas mRNA levels of leptospiral groEL, mce, loa22 and ligB genes were rapidly but transiently up-regulated (P<0.01). The treatment with closantel and HK-peptide antiserum partly reversed the infection-based down-regulated mRNA levels of lipL21 and lipL48 genes (P <0.01). Moreover, closantel caused a decrease of the infection-based up-regulated mRNA levels of groEL, mce, loa22 and ligB genes (P <0.01).

CONCLUSIONExpression levels of L.interrogans strain Lai major OMP antigens present notable changes during infection of human macrophages. There is a group of OmpR-and HK-encoding genes which may play a major role in down-regulation of expression levels of partial OMP antigens during infection.

Antigens, Bacterial ; genetics ; metabolism ; Bacterial Outer Membrane Proteins ; genetics ; metabolism ; Cell Line ; Chaperonin 60 ; genetics ; metabolism ; Humans ; Leptospira interrogans ; genetics ; immunology ; pathogenicity ; Lipoproteins ; genetics ; metabolism ; Macrophages ; microbiology