Characterization of Vascular Niche in Systemic Sclerosis by Spatial Proteomics.

BACKGROUND: Systemic sclerosis (SSc) is a connective tissue disease that can serve as a model to study vascular changes in response to inflammation, autoimmunity, and fibrotic remodeling. Although microvascular changes are the earliest histopathologic manifestation of SSc, the vascular pathophysiology remains poorly understood. METHODS: We applied spatial proteomic approaches to deconvolute the heterogeneity of vascular cells at the single-cell level in situ and characterize cellular alterations of the vascular niches of patients with SSc. Skin biopsies of patients with SSc and control individuals were analyzed by imaging mass cytometry, yielding a total of 90 755 cells including 2987 endothelial cells and 4096 immune cells. RESULTS: We identified 7 different subpopulations of blood vascular endothelial cells (VECs), 2 subpopulations of lymphatic endothelial cells, and 3 subpopulations of pericytes. A novel population of CD34+;αSMA+ (α-smooth muscle actin);CD31+ VECs was more common in SSc, whereas endothelial precursor cells were decreased. Co-detection by indexing and tyramide signal amplification confirmed these findings. The microenvironment of CD34+;αSMA+;CD31+ VECs was enriched for immune cells and myofibroblasts, and CD34+;αSMA+;CD31+ VECs expressed markers of endothelial-to-mesenchymal transition. The density of CD34+;αSMA+;CD31+ VECs was associated with clinical progression of fibrosis in SSc. CONCLUSIONS: Using spatial proteomics, we unraveled the heterogeneity of vascular cells in control individuals and patients with SSc. We identified CD34+;αSMA+;CD31+ VECs as a novel endothelial cell population that is increased in patients with SSc, expresses markers for endothelial-to-mesenchymal transition, and is located in close proximity to immune cells and myofibroblasts. CD34+;αSMA+;CD31+ VEC counts were associated with clinical outcomes of progressive fibrotic remodeling, thus providing a novel cellular correlate for the crosstalk of vasculopathy and fibrosis.

Identification and validation of anti-protein arginine methyltransferase 5 (PRMT5) antibody as a novel biomarker for systemic sclerosis (SSc).

OBJECTIVES: In the complex panorama of autoimmune diseases, the characterisation of pivotal contributing autoantibodies that are involved in disease progression remains challenging. This study aimed to employ a global antibody profiling strategy to identify novel antibodies and investigate their association with systemic sclerosis (SSc). METHODS: We implemented this strategy by conducting immunoprecipitation (IP) following on-bead digestion with the sera of patients with SSc or healthy donors, using antigen pools derived from cell lysates. The enriched antigen-antibody complex was proceeded with mass spectrometry (MS)-based quantitative proteomics and over-represented by bioinformatics analysis. The candidate antibodies were then orthogonally validated in two independent groups of patients with SSc. Mice were immunised with the target antigen, which was subsequently evaluated by histological examination and RNA sequencing. RESULTS: The IP-MS analysis, followed by validation in patients with SSc, revealed a significant elevation in anti-PRMT5 antibodies among patients with SSc. These antibodies exhibited robust diagnostic accuracy in distinguishing SSc from healthy controls and other autoimmune conditions, including systemic lupus erythematosus and Sjögren's syndrome, with an area under the curve ranging from 0.900 to 0.988. The elevation of anti-PRMT5 antibodies was verified in a subsequent independent group with SSc using an additional method, microarray. Notably, 31.11% of patients with SSc exhibited seropositivity for anti-PRMT5 antibodies. Furthermore, the titres of anti-PRMT5 antibodies demonstrated a correlation with the progression or regression trajectory in SSc. PRMT5 immunisation displayed significant inflammation and fibrosis in both the skin and lungs of mice. This was concomitant with the upregulation of multiple proinflammatory and profibrotic pathways, thereby underscoring a potentially pivotal role of anti-PRMT5 antibodies in SSc. CONCLUSIONS: This study has identified anti-PRMT5 antibodies as a novel biomarker for SSc.

Leptin Promotes Monosodium Urate Crystal-Induced Inflammation in Human and Murine Models of Gout.

Gouty arthritis is an inflammatory disease that is triggered by abnormal uric acid metabolism, which is usually attributed to obesity, a risk factor of hyperuricemia and gout attack. A high level of leptin in plasma is a marker of individuals with obesity. Population studies show that leptin promotes obesity-related arthritis, such as osteoarthritis, but it is unknown whether leptin contributes to gouty arthritis, another form of obesity-related arthritis. Our present study showed that the levels of leptin and leptin receptor in patients with active gouty arthritis were elevated. Leptin facilitates the stimulation of human synoviocytes, mouse peritoneal macrophages, and HL-60 cells induced by monosodium urate, leading to higher levels of acute gout-related proinflammatory factors. Leptin obviously exacerbates the inflammation of monosodium urate-induced acute gouty arthritis in wild-type mice, whereas that in leptin-deficient C57BL6/Job/ob mice is markedly alleviated. The proinflammatory effect of leptin in acute gouty arthritis is partly mediated by mTORC1 signaling pathway. Our study reveals that leptin may serve as a novel prevention and treatment target in acute gouty arthritis.

Sirtuin1 Protects against Systemic Sclerosis-related Pulmonary Fibrosis by Decreasing Proinflammatory and Profibrotic Processes.

Pulmonary fibrosis is the leading cause of death in systemic sclerosis (SSc). Sirtuin1 (SIRT1) is a deacetylase with known antiinflammatory and antifibrotic activity in the liver, kidney, and skin. The role of SIRT1 in SSc-related pulmonary fibrosis is unknown. In the present work, we determined that the expression of SIRT1 in peripheral blood mononuclear cells of patients with SSc with pulmonary fibrosis is lower than that in patients with SSc without pulmonary fibrosis. In in vivo studies of bleomycin-induced lung fibrosis in mice, SIRT1 activation with resveratrol reduced collagen production when it was administered either prophylactically during the inflammatory stage or after the development of fibrosis. Furthermore, SIRT1 activation or overexpression inhibited tumor necrosis factor-α-induced inflammatory responses in vitro in human fetal lung fibroblasts, depletion of SIRT1 in fibroblasts enhanced inflammation, and these effects were related to changes in the acetylation of NF-κB. In addition, SIRT1 activation or exogenous overexpression inhibited collagen production in vitro, and these manipulations also inhibited fibrosis via inactivation of transforming growth factor-ß/mothers against decapentaplegic homolog and mammalian target of rapamycin signaling. Taken together, our results show that a loss of SIRT1 may participate in the pathogenesis of SSc-related pulmonary fibrosis, and that SIRT1 activation is an effective treatment for both the early (inflammatory) and late (fibrotic) stages of pulmonary fibrosis. Thus, SIRT1 may be a promising therapeutic target in the management of SSc-related pulmonary fibrosis.

A modified murine model of systemic sclerosis: bleomycin given by pump infusion induced skin and pulmonary inflammation and fibrosis.

Daily subcutaneous (sc) injection of bleomycin (BLM) causes dermal fibrosis but rarely causes lung changes in mice. There are also significant disadvantages to this traditional model for systemic sclerosis, including a variable distribution of lesions and a requirement for repetitive procedures. The present study was undertaken to develop a convenient method of BLM administration that yields stable dermal inflammation and fibrosis with extensive and reproducible interstitial lung disease (ILD) in mice. Osmotic minipumps containing BLM (150 mg/kg) or saline were implanted sc in C57BL/6 mice and the drug was delivered as a continuous infusion over 1∼4 weeks. The time course of morphological features, collagen content, and pro-inflammatory cytokine expression in the skin and the lungs were analyzed. Pathological examination demonstrated dominant inflammatory infiltrates at week 1 and significant fibrosis at week 4. Decreased microvessel density and increased myofibroblast counts were observed in the skin of BLM-treated mice at week 4. In addition, there were obvious increases in dermal infiltration of CD45(+) leukocytes, including F4/80(+) macrophages, Gr-1(+) neutrophils, and CD3(+) T lymphocytes in BLM-treated mice. IL-1ß, IL-4, and CXCL2 transcripts were continually upregulated by BLM in the skin and lung tissues. In addition, lungs from BLM-treated mice showed significant inflammatory infiltrates and confluent subpleural fibrosis at week 4. In conclusion, this modified murine model for drug-induced systemic inflammation and fibrosis uses a single procedure and provides reproducible skin and lung lesions, mimicking human systemic sclerosis (SSc) with ILD-like manifestation.

Deubiquitination of aryl hydrocarbon receptor (AhR) by USP21 negatively regulates Th17 cells differentiation.

Aryl hydrocarbon receptor (AhR) is a key transcription factor that modulates the differentiation of T helper 17 (Th17) cells. How AhR is regulated at the post-translational level in Th17 cells remains largely unclear. Here we identify USP21 as a newly defined deubiquitinase of AhR. We demonstrate that USP21 interacts with and stabilizes AhR by removing the K48-linked polyubiquitin chains from AhR. Interestingly, USP21 inhibits the transcriptional activity of AhR in a deubiquitinating-dependent manner. USP21 deubiquitinates AhR at the K432 residue, and the maintenance of ubiquitination on this site is required for the intact transcriptional activity of AhR. Moreover, the deficiency of USP21 promotes the differentiation of Th17 cells both in vitro and in vivo. Consistently, adoptive transfer of USP21 deficient naïve CD4+ T cells elicits more severe colitis in Rag1-/- recipients. Therefore, our study reveals a novel mechanism in which USP21 deubiquitinates AhR and negatively regulates the differentiation of Th17 cells.

Attenuation of fibroblast activation and fibrosis by adropin in systemic sclerosis.

Fibrotic diseases impose a major socioeconomic challenge on modern societies and have limited treatment options. Adropin, a peptide hormone encoded by the energy homeostasis-associated (ENHO) gene, is implicated in metabolism and vascular homeostasis, but its role in the pathogenesis of fibrosis remains enigmatic. Here, we used machine learning approaches in combination with functional in vitro and in vivo experiments to characterize adropin as a potential regulator involved in fibroblast activation and tissue fibrosis in systemic sclerosis (SSc). We demonstrated consistent down-regulation of adropin/ENHO in skin across multiple cohorts of patients with SSc. The prototypical profibrotic cytokine TGFß reduced adropin/ENHO expression in a JNK-dependent manner. Restoration of adropin signaling by therapeutic application of bioactive adropin34-76 peptides in turn inhibited TGFß-induced fibroblast activation and fibrotic tissue remodeling in primary human dermal fibroblasts, three-dimensional full-thickness skin equivalents, mouse models of bleomycin-induced pulmonary fibrosis and sclerodermatous chronic graft-versus-host-disease (sclGvHD), and precision-cut human skin slices. Knockdown of GPR19, an adropin receptor, abrogated the antifibrotic effects of adropin in fibroblasts. RNA-seq demonstrated that the antifibrotic effects of adropin34-76 were functionally linked to deactivation of GLI1-dependent profibrotic transcriptional networks, which was experimentally confirmed in vitro, in vivo, and ex vivo using cultured human dermal fibroblasts, a sclGvHD mouse model, and precision-cut human skin slices. ChIP-seq confirmed adropin34-76-induced changes in TGFß/GLI1 signaling. Our study characterizes the TGFß-induced down-regulation of adropin/ENHO expression as a potential pathomechanism of SSc as a prototypical systemic fibrotic disease that unleashes uncontrolled activation of profibrotic GLI1 signaling.

Interleukin-22 inhibits bleomycin-induced pulmonary fibrosis.

Pulmonary fibrosis is a progressive and fatal fibrotic disease of the lungs with unclear etiology. Recent insight has suggested that early injury/inflammation of alveolar epithelial cells could lead to dysregulation of tissue repair driven by multiple cytokines. Although dysregulation of interleukin- (IL-) 22 is involved in various pulmonary pathophysiological processes, the role of IL-22 in fibrotic lung diseases is still unclear and needs to be further addressed. Here we investigated the effect of IL-22 on alveolar epithelial cells in the bleomycin- (BLM-) induced pulmonary fibrosis. BLM-treated mice showed significantly decreased level of IL-22 in the lung. IL-22 produced γδ T cells were also decreased significantly both in the tissues of lungs and spleens. Administration of recombinant human IL-22 to alveolar epithelial cell line A549 cells ameliorated epithelial to mesenchymal transition (EMT) and partially reversed the impaired cell viability induced by BLM. Furthermore, blockage of IL-22 deteriorated pulmonary fibrosis, with elevated EMT marker ( α -smooth muscle actin ( α -SMA)) and overactivated Smad2. Our results indicate that IL-22 may play a protective role in the development of BLM-induced pulmonary fibrosis and may suggest IL-22 as a novel immunotherapy tool in treating pulmonary fibrosis.

The role of antifibrotics in the treatment of rheumatoid arthritis-associated interstitial lung disease.

The major pulmonary complication of rheumatoid arthritis (RA) is interstitial lung disease (ILD), which causes significant morbidity and mortality and influences the natural course of disease. Recent advances in the management of arthritis have improved patient outcomes. However, exceptionally high medical needs still remain for effective therapies for the patients with ILD in RA. Better understanding of the shared and distinct pathophysiology of fibrotic diseases led to the development of novel antifibrotic agents such as nintedanib and pirfenidone. The further stratification analysis of the phase III INBUILD trial demonstrated beneficial effects of nintedanib in RA-ILD with a progressive phenotype by reducing the rate of decline in forced vital capacity (FVC) over 52 weeks by 60%. Pirfenidone is another antifibrotic agent currently under phase II clinical study (TRAIL1) aiming to evaluate its effects for RA-ILD. This review provides an overview of state-of-the-art pathogenesis and the current therapeutic options for RA-ILD, with a focus on antifibrotic strategies.

Circulating Collagen Metabolites and the Enhanced Liver Fibrosis (ELF) Score as Fibrosis Markers in Systemic Sclerosis.

Background: Serum fibrosis markers for systemic sclerosis (SSc) remain limited. The Enhanced Liver Fibrosis (ELF) score is a collagen marker set consisting of procollagen type III amino terminal propeptide (PIIINP), tissue inhibitor of metalloproteinases 1 (TIMP-1), and hyaluronic acid (HA). This longitudinal study aimed to examine the performance of the ELF score and its single analytes as surrogate outcome measures of fibrosis in SSc. Methods: Eighty-five SSc patients fulfilling the 2013 ACR/EULAR criteria with the absence of chronic liver diseases were enrolled. Serum PIIINP, TIMP-1, HA, and the ELF score were measured and correlated with clinical variables including the modified Rodnan skin score (mRSS) and interstitial lung disease (ILD). Twenty SSc patients underwent a follow-up serological testing and mRSS evaluation during treatment with immunosuppressants and/or anti-fibrotic drugs. Results: Serum PIIINP, TIMP-1, and ELF score were significantly higher in patients with SSc than in healthy controls [PIIINP: 10.31 (7.83-14.10) vs. 5.61 (4.69-6.30), p < .001; TIMP-1: 110.73 (66.21-192.45) vs. 61.81 (48.86-85.24), p < .001; ELF: 10.34 (9.91-10.86) vs. 9.68 (9.38-9.99), p < .001]. Even higher levels of PIIINP, TIMP-1, and ELF score were found in patients with diffuse cutaneous SSc than those with limited cutaneous SSc. At baseline, both PIIINP and ELF score showed good correlation with mRSS (PIIINP: r = .586, p < .001; ELF: r = .482, p < .001). Longitudinal analysis showed that change in PIIINP positively correlated with change in mRSS (r = 0.701, p = .001), while change in ELF score were not related, in a statistical context, to the change in mRSS (ELF: r = .140, p = .555). Serum TIMP-1 was significantly higher in SSc patients with ILD, compared to the matched group of patients without ILD [109.45 (93.05-200.09) vs. 65.50 (40.57-110.73), p = 0.007]. Conclusion: In patients with SSc, the ELF score well correlates with the extent of skin fibrosis, while serum PIIINP is a sensitive marker for longitudinal changes of skin fibrosis. In the future, circulating collagen metabolites may potentially be used to evaluate therapeutic effects of anti-fibrotic treatments in the disease.

Contribution to the peripheral vasculopathy and endothelial cell dysfunction by CXCL4 in Systemic Sclerosis.

BACKGROUND: CXCL4, a chemokine with anti-angiogenic property, is involved in systemic sclerosis (SSc) related pulmonary arterial hypertension (PAH). OBJECTIVE: To investigated the contribution of CXCL4 to SSc development by focusing on the correlation of circulatory CXCL4 levels with their peripheral vasculopathy, and the effect of CXCL4 on endothelial cell dysfunction and the potential signaling. METHODS: We measured the plasma CXCL4 levels in 58 patients with SSc, 10 patients with the very early diagnosis of SSc (VEDOSS), and 80 healthy controls (HCs). Then, CXCL4 concentrations were correlated with clinical features, especially the peripheral vasculopathy. These observations were further validated in an additional cohort. Moreover, we studied the anti-angiogenic effects of CXCL4 and the underlying downstream signaling in human umbilical vein endothelial cells (HUVECs) in vitro. RESULTS: Circulating CXCL4 levels were 103.62 % higher in patients with SSc and 201.51 % higher in patients with VEDOSS than matched HCs, which were confirmed in two independent cohorts. CXCL4 levels were associated with digital ulcers (DU) and nailfold videocapillaroscopy (NVC) abnormalities in SSc. The proliferation, migration, and tube formation of HUVECs were inhibited by CXCL4 or SSc derived plasma, which reversed by CXCL4 neutralizing antibody, but failed by CXCR3 inhibitor. CXCL4 downregulated the transcription factor Friend leukaemia integration factor-1 (Fli-1) via c-Abl signaling. Furthermore, CXCL4 blocked the transforming growth factor (TGF) -ß or platelet-derived growth factor (PDGF) induced cell proliferation of HUVECs. CONCLUSIONS: CXCL4 may contribute to peripheral vasculopathy in SSc by downregulating Fli-1 via c-Abl signaling in endothelial cells and interfering angiogenesis.

Exome-Wide Association Analysis Suggests LRP2BP as a Susceptibility Gene for Endothelial Injury in Systemic Sclerosis in the Han Chinese Population.

Genetic factors play a key role in the pathogenesis of autoimmune diseases, whereas the disease-causing variants remain largely unknown. Herein, we performed an exome-wide association study of systemic sclerosis in a Han Chinese population. In the discovery stage, 527 patients with systemic sclerosis and 5,024 controls were recruited and genotyped. In the validation study, an independent sample set of 479 patients and 1,096 controls were examined. In total, we found that four independent signals reached genome-wide significance. Among them, rs7574865 (Pcombined = 3.87 × 10-12) located within signal transducer and activator of transcription 4 gene was identified previously using samples of European ancestry. Additionally, another signal including three SNPs in linkage disequilibrium might be unreported susceptibility loci located in the epidermis differentiation complex region. Furthermore, two SNPs located within exon 3 of IGHM (rs45471499, Pcombined = 1.15 × 10-9) and upstream of LRP2BP (rs4317244, Pcombined = 4.17 × 10-8) were found. Moreover, rs4317244 was identified as an expression quantitative trait locus for LRP2BP that regulates tight junctions, cell cycle, and apoptosis in endothelial cell lines. Collectively, our results revealed three signals associated with systemic sclerosis in Han Chinese and suggested the importance of LRP2BP in systemic sclerosis pathogenesis. Given the limited sample size and discrepancies between previous results and our study, further studies in multiethnic populations are required for verification.

Ultrasound assessment of skin thickness and stiffness: the correlation with histology and clinical score in systemic sclerosis.

BACKGROUND: Ultrasound is a useful tool to evaluate and quantify skin lesions. Few studies have assessed the criterion validity of skin ultrasound in systemic sclerosis (SSc). The aims of the study were to investigate skin thickness and stiffness using ultrasound and shear wave elastography (SWE) in SSc and to validate skin ultrasound measurements against histological skin thickness. METHODS: A total of 22 patients with diffuse cutaneous SSc (dcSSc), 22 with limited cutaneous SSc (lcSSc), and 22 age- and gender-matched healthy controls were enrolled. Skin thickness and stiffness were measured by B-mode ultrasound with SWE imaging on the bilateral fingers and hands. Additional ultrasound evaluation was carried out in 13 patients (9 dcSSc and 4 lcSSc) on their dorsal forearms, followed by skin biopsy conducted in the same skin areas. Correlations between ultrasound measurements and histological skin thickness and modified Rodnan skin score (mRSS) were investigated using Spearman's correlation. RESULTS: Compared with controls, ultrasound-measured skin thickness and skin stiffness were significantly higher in patients with SSc (p < 0.001) and even higher in those with dcSSc. No clear correlation could be established between ultrasound-determined skin thickness and stiffness at the same site. Ultrasound-measured skin thickness correlated well with histological skin thickness (r = 0.6926, p = 0.009). A weaker association was also observed between histological skin thickness and local mRSS (r = 0.5867, p = 0.050). CONCLUSIONS: Ultrasound is a reliable tool for quantifying skin involvement in SSc. Ultrasound-measured skin thickness showed good agreement with histological skin thickness.

Promotion of Myofibroblast Differentiation and Tissue Fibrosis by the Leukotriene B4 -Leukotriene B4 Receptor Axis in Systemic Sclerosis.

OBJECTIVE: To investigate the role of the inflammatory lipid mediator leukotriene B4 (LTB4 ) and its receptor, BLT1, in the development and progression of systemic sclerosis (SSc). METHODS: Serum levels of LTB4 were compared in 64 patients with SSc and 80 healthy controls. Skin and lung tissue sections from patients with SSc and healthy donors were immunostained for leukotriene A4 hydrolase (LTA4 H), the critical enzyme for LTB4 synthesis, and BLT1, in combination with different cell markers. In mouse models of SSc using bleomycin or angiotensin II challenge or immunization with the DNA topoisomerase I, genetic or pharmacologic interruption of the LTB4 -BLT1 axis in mice was carried out to assess its effects on systemic disease features and myofibroblast markers. Immunoblotting was performed to examine the signaling pathway in fibroblasts and endothelial cells following stimulation with LTB4 or with serum from SSc patients. RESULTS: Serum LTB4 levels were 44.93% higher in patients with SSc than in matched healthy controls (mean ± SD 220.3 ± 74.75 pg/ml versus 152.0 ± 68.05 pg/ml; P < 0.0001), and this was associated with the patient subsets of SSc-associated interstitial lung disease and diffuse cutaneous SSc. Levels of LTA4 H and BLT1 were increased in lesional areas of the skin and lungs of SSc patients, and both were abundant in myofibroblasts and endothelial cells. Interruption of the LTB4 -BLT1 axis in mouse models of SSc significantly mitigated dermal and pulmonary fibrosis, with 54.00% and 52.65% fewer α-smooth muscle actin-positive myofibroblasts accumulating in the skin and lungs of mice, respectively, after bleomycin challenge. Immunoblotting of cultures with recombinant LTB4 -stimulated fibroblasts and endothelial cells or with serum from SSc patients showed that fibroblast-myofibroblast and endothelial-mesenchymal transitions were promoted via BLT1, and that this was dependent on activation of the phosphatidylinositol 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway but independent of the release of transforming growth factor ß (TGFß) by fibroblasts or endothelial cells. CONCLUSION: The LTB4 -BLT1 axis may contribute to fibrosis in SSc by directly promoting myofibroblast differentiation via the PI3K/Akt/mTOR pathway, and this appears to operate independently of autocrine secretion of TGFß.

Polyneuropathy as Novel Initial Manifestation in a Case of "Nonsecretory" POEMS Syndrome with Sjögren's Syndrome.

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) is a paraneoplastic syndrome driven by plasma cell dyscrasias. We report a patient with novel initial manifestation of polyneuropathy, which was considered due to Sjögren's syndrome but with poor response to methylprednisolone (120 mg/d) and intravenous immunoglobulin (IVIg). Further investigation by imaging tests and following biopsy eventually confirmed the diagnosis of POEMS syndrome secondary to solitary plasmocytoma. To our knowledge, this is the first reported case of POEMS syndrome with Sjögren's syndrome occurring in the absence of a peripheral monoclonal gammopathy, highlighting the diagnostic challenges posed by this disease and reviewing the diagnostic role of (18) F-FDG PET/CT in POEMS syndrome.

Clinical Association of Chemokine (C-X-C motif) Ligand 1 (CXCL1) with Interstitial Pneumonia with Autoimmune Features (IPAF).

The term "interstitial pneumonia with autoimmune features" (IPAF) has been recently proposed. We here investigate the clinical characteristics of IPAF and evaluate the clinical implications of CXCL1-CXCR2 axis in IPAF. An increased plasma level of CXCL1 was exhibited in IPAF compared to idiopathic interstitial pneumonia (IIP), chronic obstructive pulmonary disease (COPD), and healthy controls. Additionally, plasma CXCL1 levels were clinically associated with diffusing capacity of the lungs for carbon monoxide (DLCO), erythrocyte sedimentation rate (ESR), and involved parenchyma extension in IPAF. Furthermore, circulating CXCL1 levels were highest in IPAF patients with acute exacerbations. CXCR2, the chemokine receptor for CXCL1, was readily observed in inflammatory aggregates and endothelial cells in IPAF lungs, but was lower in IIP lungs and healthy lungs. Interestingly, increased CXCL1 concentrations in BALF paralleled neutrophil counts in IPAF. Overall, the plasma concentrations of CXCL1 indicated the disease activity and prognosis in IPAF. Thus, the CXCL1/CXCR2 axis appears to be involved in the progression of IPAF.

Interleukin 37 limits monosodium urate crystal-induced innate immune responses in human and murine models of gout.

BACKGROUND: Interleukin (IL)-37 has emerged as a fundamental inhibitor of innate immunity. Acute gout is a self-limiting inflammatory response to monosodium urate (MSU) crystals. In the current study, we assessed the preventive and therapeutic effect of recombinant human IL-37 (rhIL-37) in human and murine gout models. METHODS: We investigated the expression of IL-37 in patients with active and inactive gouty arthritis and assessed the effect of rhIL-37 in human and murine gout models: a human monocyte cell line (THP-1) and human synovial cells (containing macrophage-like and fibroblast-like synoviocytes) exposed to MSU crystals, a peritoneal murine model of gout and a murine gouty arthritis model. After inhibition of Mer receptor tyrosine kinase (Mertk), levels of IL-1ß, IL-8 and chemokine (C-C motif) ligand 2 (CCL-2) were detected by ELISA and expression of mammalian homologs of the drosophila Mad gene 3 (Smad), suppressor of cytokine signaling 3 (SOCS3), NACHT-LRR-PYD-containing protein 3 (NLRP3), and IL-8R of THP-1 were assessed by qPCR and western blot to explore the molecular mechanisms. RESULTS: Our studies strongly indicated that rhIL-37 played a potent immunosuppressive role in the pathogenesis of experimental gout models both in vitro and in vivo, by downregulating proinflammatory cytokines and chemokines, markedly reducing neutrophil and monocyte recruitment, and mitigating pathological joint inflammation. In our studies, rhIL-37 suppressed MSU-induced innate immune responses by enhancing expression of Smad3 and IL-1R8 to trigger multiple intracellular switches to block inflammation, including inhibition of NLRP3 and activation of SOCS3. Mertk signaling participated in rhIL-37 inhibitory pathways in gout models. By inhibition of Mertk, the anti-inflammatory effect of rhIL-37 was partly abrogated, and IL-1R8, Smad3 and S​OCS3 expression were suppressed, whereas NLRP3 expression was reactivated. CONCLUSIONS: Our studies reveal that IL-37 limits runaway inflammation initiated by MSU crystal-induced immune responses, partly in a Mertk-dependent fashion. Thus, rhIL-37 has both preventive and therapeutic effects in gouty arthritis.

Cardiac arrhythmias as the initial manifestation of adult primary Sjögren's syndrome: a case report and literature review.

Two middle-aged female patients presenting with heart palpitation and electrocardiogram revealed complex cardiac arrhythmias. A review of systems was positive for dry mouth and transient arthralgia, while laboratory and instrumental tests enabled us to make the diagnosis of primary Sjögren's syndrome (pSS). Cardiac electrophysiology revealed atrioventricular node dysfunction and impaired intraventricular conduction. Prednisone therapy induced a significant improvement in symptoms and electrocardiographic readings. The diagnosis of pSS should be considered in a patient presenting with complex cardiac arrhythmias.