Background:Pulmonary arterial hypertension (PAH), particularly connective tissue disease-associated PAH (CTD-PAH), is a progressive disease and novel therapeutic agents based on the specific ...molecular pathogenesis are desired. In the pathogenesis of CTD-PAH, inflammation, immune cell abnormality, and fibrosis play important roles. However, the existing mouse pulmonary hypertension (PH) models do not reflect these features enough. The relationship between inflammation and hypoxia is still unclear.Methods and Results:Intraperitoneal administration of pristane, a kind of mineral oil, and exposure to chronic hypoxia were combined, and this model is referred to as pristane/hypoxia (PriHx) mice. Hemodynamic and histological analyses showed that the PriHx mice showed a more severe phenotype of PH than pristane or hypoxia alone. Immunohistological and flow cytometric analyses revealed infiltration of immune cells, including hemosiderin-laden macrophages and activated CD4+helper T lymphocytes in the lungs of PriHx mice. Pristane administration exacerbated lung fibrosis and elevated the expression of fibrosis-related genes. Inflammation-related genes such asIl6andCxcl2were also upregulated in the lungs of PriHx mice, and interleukin (IL)-6 blockade by monoclonal anti-IL-6 receptor antibody MR16-1 ameliorated PH of PriHx mice.Conclusions:A PriHx model, a novel mouse model of PH reflecting the pathological features of CTD-PAH, was developed through a combination of pristane administration and exposure to chronic hypoxia.
Rheumatoid arthritis (RA)-associated IgG antibodies such as anti-citrullinated protein antibodies (ACPAs) have diverse glycosylation variants; however, key sugar chains modulating the arthritogenic ...activity of IgG remain to be clarified. Here, we show that reduced sialylation is a common feature of RA-associated IgG in humans and in mouse models of arthritis. Genetically blocking sialylation in activated B cells results in exacerbation of joint inflammation in a collagen-induced arthritis (CIA) model. On the other hand, artificial sialylation of anti-type II collagen antibodies, including ACPAs, not only attenuates arthritogenic activity, but also suppresses the development of CIA in the antibody-infused mice, whereas sialylation of other IgG does not prevent CIA. Thus, our data demonstrate that sialylation levels control the arthritogenicity of RA-associated IgG, presenting a potential target for antigen-specific immunotherapy.
Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease, and many peripheral immune cell populations (ICPs) are thought to be altered according to the course of the disease. However, ...it is unclear which ICPs are associated with the clinical phenotypes of SLE. We analyzed peripheral blood mononuclear cells (PBMCs) of 28 SLE patients using mass cytometry and identified 30 ICPs. We determined the proliferative activity of ICPs by measuring the proportion of cells expressing specific markers and Ki-67 among CD45+ cells (Ki-67+ proportion). We observed an increased Ki-67+ proportion for many ICPs of SLE patients and examined the association between their Ki-67+ proportions and clinical findings. The Ki-67+ proportions of five ICPs classical monocyte (cMo), effector memory CD8+ T cell (CD8Tem), CXCR5- naive B cell (CXCR5- nB), and CXCR5- IgD-CD27- B cell (CXCR5- DNB) were identified as clinically important factors. The SLE Disease Activity Index (SLEDAI) was positively correlated with cMo and plasma cells (PC). The titer of anti-DNA antibodies was positively correlated with cMo, CXCR5- nB, and CXCR5- DNB. The C4 level was negatively correlated with CXCR5- DNB. The bioactivity of type I interferon was also positively correlated with these ICPs. Fever and renal involvement were associated with cMo. Rash was associated with CD8Tem and CXCR5- DNB. On the basis of the proliferative activity among five ICPs, SLE patients can be classified into five clusters showing different SLE phenotypes. Evaluation of the proliferative activity in each ICP can be linked to the clinical phenotypes of individual SLE patients and help in the treatment strategy.
Lymphocyte migration is mediated by G protein-coupled receptors (GPCRs) that respond to chemoattractive molecules. After their activation, GPCRs are phosphorylated by different GPCR kinases (GRKs), ...which produces distinct functional outcomes through β-arrestins. However, the molecular machinery that targets individual GRKs to activated GPCRs remains elusive. Here, we identified a protein complex consisting of copper metabolism MURR1 domain-containing (COMMD) 3 and COMMD8 (COMMD3/8 complex) as an adaptor that selectively recruits a specific GRK to chemoattractant receptors and promotes lymphocyte chemotaxis. COMMD8, whose stability depended on COMMD3, was recruited to multiple chemoattractant receptors. Deficiency of COMMD8 or COMMD3 impaired B cell migration and humoral immune responses. Using CXC-chemokine receptor 4 (CXCR4) as a model, we demonstrated that the COMMD3/8 complex selectively recruited GRK6 and induced GRK6-mediated phosphorylation of the receptor and activation of β-arrestin-mediated signaling. Thus, the COMMD3/8 complex is a specificity determinant of GRK targeting to GPCRs and represents a point of regulation for immune responses.
Abstract
The immunological basis of the clinical heterogeneity in autoimmune vasculitis remains poorly understood. In this study, we conduct single-cell transcriptome analyses on peripheral blood ...mononuclear cells (PBMCs) from newly-onset patients with microscopic polyangiitis (MPA). Increased proportions of activated CD14
+
monocytes and CD14
+
monocytes expressing interferon signature genes (ISGs) are distinctive features of MPA. Patient-specific analysis further classifies MPA into two groups. The MPA-MONO group is characterized by a high proportion of activated CD14
+
monocytes, which persist before and after immunosuppressive therapy. These patients are clinically defined by increased monocyte ratio in the total PBMC count and have a high relapse rate. The MPA-IFN group is characterized by a high proportion of ISG
+
CD14
+
monocytes. These patients are clinically defined by high serum interferon-alpha concentrations and show good response to immunosuppressive therapy. Our findings identify the immunological phenotypes of MPA and provide clinical insights for personalized treatment and accurate prognostic prediction.
Abstract
Objective
B-cell activating factor (BAFF) is implicated in SLE pathogenesis. Blocking BAFF signalling has contributed to reducing glucocorticoid dosage and preventing organ damage. However, ...clinical characteristics of patients who may benefit from this therapy are not yet fully elucidated. Therefore, we identified patients with high BAFF-bioactivity to investigate their clinical characteristics and BAFF-producing cells.
Methods
We established the reporter cell for BAFF and investigated the clinical characteristics of SLE patients with high BAFF-bioactivity. We identified BAFF-expressing kidney cells using publicly available scRNA-seq data and immunohistological analysis. SLE patients were stratified based on the bioactivity of BAFF and type-I IFN (IFN-I) to identify associated characteristic clinical manifestations.
Results
SLE patients, especially patients with LN, had significantly higher serum BAFF-bioactivity than healthy controls (HC) and non-LN patients. Additionally, single-cell-RNA-seq data and immunohistological analysis of kidney samples from LN patients revealed that BAFF is expressed in glomerular macrophages and mesangial cells. Notably, BAFF bioactivity was elevated in the urine of LN patients compared with that of non-LN patients, while no IFN-I bioactivity was detected in the urine. Furthermore, SLE stratification based on bioactivities of serum BAFF and IFN-I revealed the clinical characteristics of patients: high BAFF represented patients with LN and high IFN-I represented patients with blood and skin manifestations.
Conclusions
Monitoring urinary BAFF-bioactivity may be valuable in diagnosing LN. Furthermore, stratification based on serum BAFF and IFN-I bioactivities may allow the identification of appropriate patients for biologics targeting BAFF and IFN-I.
Objective
Semaphorin 4D (Sema4D)/CD100 has pleiotropic roles in immune activation, angiogenesis, bone metabolism, and neural development. We undertook this study to investigate the role of Sema4D in ...rheumatoid arthritis (RA).
Methods
Soluble Sema4D (sSema4D) levels in serum and synovial fluid were analyzed by enzyme‐linked immunosorbent assay. Cell surface expression and transcripts of Sema4D were analyzed in peripheral blood cells from RA patients, and immunohistochemical staining of Sema4D was performed in RA synovium. Generation of sSema4D was evaluated in an ADAMTS‐4–treated monocytic cell line (THP‐1 cells). The efficacy of anti‐Sema4D antibody was evaluated in mice with collagen‐induced arthritis (CIA).
Results
Levels of sSema4D were elevated in both serum and synovial fluid from RA patients, and disease activity markers were correlated with serum sSema4D levels. Sema4D‐expressing cells also accumulated in RA synovium. Cell surface levels of Sema4D on CD3+ and CD14+ cells from RA patients were reduced, although levels of Sema4D transcripts were unchanged. In addition, ADAMTS‐4 cleaved cell surface Sema4D to generate sSema4D in THP‐1 cells. Soluble Sema4D induced tumor necrosis factor α (TNFα) and interleukin‐6 (IL‐6) production from CD14+ monocytes. IL‐6 and TNFα induced ADAMTS‐4 expression in synovial cells. Treatment with an anti‐Sema4D antibody suppressed arthritis and reduced proinflammatory cytokine production in CIA.
Conclusion
A positive feedback loop involving sSema4D/IL‐6 and TNFα/ADAMTS‐4 may contribute to the pathogenesis of RA. The inhibition of arthritis by anti‐Sema4D antibody suggests that Sema4D represents a potential therapeutic target for RA.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Chronic obstructive pulmonary disease (COPD/emphysema) is a life-threatening disorder and there are few effective therapies. Cigarette smoke-induced oxidative stress, airway inflammation, and ...apoptosis of lung cells have been reported to be involved in the pathogenesis of COPD/emphysema and lead to alveolar septal destruction. Here we show that the expression level of FCH and double SH3 domains 1 (FCHSD1) was drastically increased in mice in response to elastase instillation, an experimental model of COPD. FCHSD1 is a member of the F-BAR family with two SH3 domains. We found that
knockout (
) mice were protected against airspace enlargement induced by elastase. Elastase-instilled lungs of
mice showed reduced inflammation and apoptosis compared with WT mice. We also found that elastase-induced reduction of Sirtuin 1 (SIRT1) levels, a histone deacetylase reported to protect against emphysema, was attenuated in the lungs of
mice. Furthermore, FCHSD1 deficiency enhanced nuclear translocation of nuclear factor-like 2 (NRF2),
redox-sensitive transcription factor, following H
O
stimulation. Conversely,
overexpression inhibited
nuclear translocation and increased the reduction of SIRT1 levels. Notably, FCHSD1 interacted with NRF2 and SNX9. Our results show that FCHSD1 forms a multicomplex with NRF2 and SNX9 in the cytosol that prevents NRF2 from translocating to the nucleus. We propose that FCHSD1 promotes initiation of emphysema development by inhibiting nuclear translocation of NRF2, which leads to down-regulation of SIRT1.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Neuropilin-1 (Npn-1) is a receptor shared by class 3 semaphorins and heparin-binding forms of vascular endothelial growth factor (VEGF), protein families that regulate endothelial and neuronal-cell ...function. Ligand interaction with Npn-1 dictates the choice of signal transducer; plexins transduce semaphorin signals, and VEGF receptors transduce VEGF signals. It is not clear how class 3 semaphorins affect endothelial-cell function and how the shared receptor Npn-1 selects its ligand. We report that semaphorin3A (Sema3A) inhibits endothelial-cell lamellipodia formation, adhesion, survival, proliferation, and cord formation. VEGF165, but not VEGF121, could block all these effects of Sema3A. VEGF165 competed with Sema3A for binding to endothelial cells, effectively reduced cell-surface Npn-1, and promoted its internalization. Use of soluble forms of Npn-1 or VEGF receptor-1 to block VEGF165 binding to Npn-1 or to VEGF receptors provided evidence that surface Npn-1 and VEGF receptors are required for VEGF165-induced Npn-1 internalization. Sema3A also reduced cell-surface Npn-1 in endothelial cells and promoted its internalization, but required a higher concentration than VEGF165. These results demonstrate that preferential receptor binding and internalization by a ligand are mechanisms by which the common receptor Npn-1 can play an essential role in prioritizing conflicting signals.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Inappropriate activation of neutrophils plays a pathological role in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The aim of this study was to investigate the functions of ...semaphorin 4D (SEMA4D) in regulation of neutrophil activation, and its involvement in AAV pathogenesis.
Serum levels of soluble SEMA4D were evaluated by ELISA. Blood cell-surface expression of membrane SEMA4D was evaluated by flow cytometry. To determine the functional interactions between neutrophil membrane SEMA4D and endothelial plexin B2, wild-type and
mice neutrophils were cultured with an endothelial cell line (MS1) stained with SYTOX green, and subjected to neutrophil extracellular trap (NET) formation assays. The efficacy of treating human neutrophils with recombinant plexin B2 was assessed by measuring the kinetic oxidative burst and NET formation assays.
Serum levels of soluble SEMA4D were elevated in patients with AAV and correlated with disease activity scores. Cell-surface expression of SEMA4D was downregulated in neutrophils from patients with AAV, a consequence of proteolytic cleavage of membrane SEMA4D. Soluble SEMA4D exerted pro-inflammatory effects on endothelial cells. Membranous SEMA4D on neutrophils bound to plexin B2 on endothelial cells, and this interaction decreased NET formation. Recombinant plexin B2 suppressed neutrophil Rac1 activation through SEMA4D's intracellular domain, and inhibited pathogen-induced or ANCA-induced oxidative burst and NET formation.
Neutrophil surface SEMA4D functions as a negative regulator of neutrophil activation. Proteolytic cleavage of SEMA4D as observed in patients with AAV may amplify neutrophil-mediated inflammatory responses. SEMA4D is a promising biomarker and potential therapeutic target for AAV.
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