Stabilizing the integrity of intestinal barrier to control arthritis.

With great interest, we have read the recent article "Expression of HIF1α in intestinal epithelium restricts arthritis inflammation by inhibiting RIPK3-induced cell death machinery" published by Lyu et al. in Annals of the Rheumatic Diseases. The authors pose that the expression of hypoxia-inducible factor 1 alpha in intestinal epithelial cells represents a crucial check point for the development of arthritis by impeding necroptosis of intestinal epithelial cells and safeguarding the intestinal barrier integrity.

Targeting TLR Signaling Cascades in Systemic Lupus Erythematosus and Rheumatoid Arthritis: An Update.

Evidence from animal models and human genetics implicates Toll-like Receptors (TLRs) in the pathogenesis of Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA). Endosomal TLRs sensing nucleic acids were proposed to induce lupus-promoting signaling in dendritic cells, B cells, monocytes, and macrophages. Ligation of TLR4 in synovial macrophages and fibroblast-like synoviocytes (FLSs) by endogenous ligands was suggested to induce local production of mediators that amplify RA synovitis.

Solid Cancers and Rheumatoid Arthritis.

Since the initial observation that patients with rheumatoid arthritis (RA) have an excess risk of developing hematologic malignancies [...

Comparison of the Inflammatory Circuits in Psoriasis Vulgaris, Non‒Pustular Palmoplantar Psoriasis, and Palmoplantar Pustular Psoriasis.

Palmoplantar pustular psoriasis (PPPP) and non‒pustular palmoplantar psoriasis (NPPP) are localized, debilitating forms of psoriasis. The inflammatory circuits involved in PPPP and NPPP are not well-understood. To compare the cellular and immunological features that differentiate PPPP and NPPP, skin biopsies were collected from a total of 30 participants with PPPP, NPPP, and psoriasis vulgaris (PV) and from 10 healthy participants.

Augmenting MNK1/2 activation by c-FMS proteolysis promotes osteoclastogenesis and arthritic bone erosion.

Osteoclasts are bone-resorbing cells that play an essential role in homeostatic bone remodeling and pathological bone erosion. Macrophage colony stimulating factor (M-CSF) is abundant in rheumatoid arthritis (RA). However, the role of M-CSF in arthritic bone erosion is not completely understood.

Pharmacokinetics and pharmacodynamics of itepekimab in healthy adults and patients with asthma: Phase I first-in-human and first-in-patient trials.

Itepekimab is a monoclonal antibody that targets interleukin (IL-33) and has been shown to reduce airway inflammation and associated tissue damage in preclinical studies. We assessed the safety, tolerability, pharmacokinetics (PKs), and pharmacodynamic profiles of single-ascending and multiple-ascending doses of itepekimab in two randomized, double-blind, placebo-controlled phase I studies. Healthy adults (N = 40) were randomized to the single-dose study and patients with moderate asthma (N = 23) to the multiple-dose study.

RA-map: building a state-of-the-art interactive knowledge base for rheumatoid arthritis.

Rheumatoid arthritis (RA) is a progressive, inflammatory autoimmune disease of unknown aetiology. The complex mechanism of aetiopathogenesis, progress and chronicity of the disease involves genetic, epigenetic and environmental factors. To understand the molecular mechanisms underlying disease phenotypes, one has to place implicated factors in their functional context.

TNF-induced inflammatory genes escape repression in fibroblast-like synoviocytes: transcriptomic and epigenomic analysis.

Objective: We investigated genome-wide changes in gene expression and chromatin remodelling induced by tumour necrosis factor (TNF) in fibroblast-like synoviocytes (FLS) and macrophages to better understand the contribution of FLS to the pathogenesis of rheumatoid arthritis (RA).

Methods: FLS were purified from patients with RA and CD14 human monocyte-derived macrophages were obtained from healthy donors. RNA-sequencing, histone 3 lysine 27 acetylation (H3K27ac), chromatin immunoprecipitation-sequencing (ChIP-seq) and assay for transposable accessible chromatin by high throughput sequencing (ATAC-seq) were performed in control and TNF-stimulated cells.

Computational Systems Biology Approach for the Study of Rheumatoid Arthritis: From a Molecular Map to a Dynamical Model.

In this work we present a systematic effort to summarize current biological pathway knowledge concerning Rheumatoid Arthritis (RA). We are constructing a detailed molecular map based on exhaustive literature scanning, strict curation criteria, re-evaluation of previously published attempts and most importantly experts' advice. The RA map will be web-published in the coming months in the form of an interactive map, using the MINERVA platform, allowing for easy access, navigation and search of all molecular pathways implicated in RA, serving thus, as an on line knowledgebase for the disease.

Functionally distinct disease-associated fibroblast subsets in rheumatoid arthritis.

Fibroblasts regulate tissue homeostasis, coordinate inflammatory responses, and mediate tissue damage. In rheumatoid arthritis (RA), synovial fibroblasts maintain chronic inflammation which leads to joint destruction. Little is known about fibroblast heterogeneity or if aberrations in fibroblast subsets relate to pathology.

Tumor Necrosis Factor dynamically regulates the mRNA stabilome in rheumatoid arthritis fibroblast-like synoviocytes.

During rheumatoid arthritis (RA), Tumor Necrosis Factor (TNF) activates fibroblast-like synoviocytes (FLS) inducing in a temporal order a constellation of genes, which perpetuate synovial inflammation. Although the molecular mechanisms regulating TNF-induced transcription are well characterized, little is known about the impact of mRNA stability on gene expression and the impact of TNF on decay rates of mRNA transcripts in FLS. To address these issues we performed RNA sequencing and genome-wide analysis of the mRNA stabilome in RA FLS.

The impact of disease activity and tumour necrosis factor-α inhibitor therapy on cytokine levels in juvenile idiopathic arthritis.

The aim of this study was to evaluate prospectively cytokine levels and disease activity in juvenile idiopathic arthritis (JIA) patients treated with and without tumour necrosis factor (TNF)-α inhibitors. TNF-α inhibitor-naive JIA subjects were followed prospectively for 6 months. Cytokine levels of TNF-α, interleukin (IL)-1β, IL-6, IL-8, IL-10 and IL-17 were measured at baseline for JIA subjects and healthy controls (HCs).

TNF biology, pathogenic mechanisms and emerging therapeutic strategies.

TNF is a pleiotropic cytokine with important functions in homeostasis and disease pathogenesis. Recent discoveries have provided insights into TNF biology that introduce new concepts for the development of therapeutics for TNF-mediated diseases. The model of TNF receptor signalling has been extended to include linear ubiquitination and the formation of distinct signalling complexes that are linked with different functional outcomes, such as inflammation, apoptosis and necroptosis.

Blood-induced arthropathy in hemophilia: mechanisms and heterogeneity.

Hemophilia A is an X-linked bleeding disorder that can be largely controlled by treatment with recombinant factor VIII. However, this treatment is only partially effective in preventing hemophilic arthropathy (HA), a debilitating degenerative joint disease that is caused by intra-articular bleeding events. The disease progression of HA has several distinct steps, beginning with hemophilic synovitis (HS), a hyperplasia of the synovial lining coupled with a neovascular response, followed by joint erosion with cartilage destruction and erosion of the underlying bone.

Prolonged tumor necrosis factor α primes fibroblast-like synoviocytes in a gene-specific manner by altering chromatin.

Objective: During the course of rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) are chronically exposed to an inflammatory milieu. The purpose of this study was to test the hypothesis that prolonged exposure of FLS to tumor necrosis factor α (TNFα) augments inflammatory responses to secondary stimuli (priming effect).

Methods: FLS obtained from RA patients were exposed to TNFα for 3 days and were then stimulated with interferons (IFNs).

Modulation of TNF-induced macrophage polarization by synovial fibroblasts.

Mesenchymal stromal cells have emerged as powerful modulators of the immune system. In this study, we explored how the human macrophage response to TNF is regulated by human synovial fibroblasts, the representative stromal cell type in the synovial lining of joints that become activated during inflammatory arthritis. We found that synovial fibroblasts strongly suppressed TNF-mediated induction of an IFN-β autocrine loop and downstream expression of IFN-stimulated genes (ISGs), including chemokines CXCL9 and CXCL10 that are characteristic of classical macrophage activation.

Kinase inhibitors: a new tool for the treatment of rheumatoid arthritis.

Despite aggressive immunosuppression with biologics and traditional DMARDs, achieving disease remission remains an unmet goal for most rheumatoid arthritis (RA) patients. In this context, there is a demand for novel treatment strategies, with kinase inhibitors expected to enrich the existing therapeutic armamentarium. In RA some kinases participate in the generation of pathogenic signaling cascades.

iRHOM2 is a critical pathogenic mediator of inflammatory arthritis.

iRHOM2, encoded by the gene Rhbdf2, regulates the maturation of the TNF-α convertase (TACE), which controls shedding of TNF-α and its biological activity in vivo. TACE is a potential target to treat TNF-α-dependent diseases, such as rheumatoid arthritis, but there are concerns about potential side effects, because TACE also protects the skin and intestinal barrier by activating EGFR signaling. Here we report that inactivation of Rhbdf2 allows tissue-specific regulation of TACE by selectively preventing its maturation in immune cells, without affecting its homeostatic functions in other tissues.

Tumor necrosis factor α induces sustained signaling and a prolonged and unremitting inflammatory response in rheumatoid arthritis synovial fibroblasts.

Objective: The nonresolving character of synovial inflammation in rheumatoid arthritis (RA) is a conundrum. To identify the contribution of fibroblast-like synoviocytes (FLS) to the perpetuation of synovitis, we investigated the molecular mechanisms that govern the tumor necrosis factor α (TNFα)-driven inflammatory program in human FLS.

Methods: FLS obtained from the synovial tissues of patients with RA or osteoarthritis were stimulated with TNFα and assayed for gene expression and cytokine production by real-time quantitative reverse transcription-polymerase chain reaction analysis and enzyme-linked immunosorbent assay.

The interferon signature and STAT1 expression in rheumatoid arthritis synovial fluid macrophages are induced by tumor necrosis factor α and counter-regulated by the synovial fluid microenvironment.

Objective: Type I interferons (IFNs) have emerged as potential activators of the IFN signature and elevated STAT-1 expression in rheumatoid arthritis (RA) synovium, but mechanisms that induce synovial IFN expression are unknown. Recently, tumor necrosis factor α (TNFα) was shown to induce a delayed IFN response in macrophages. We undertook this study to test whether TNFα, classically thought to activate inflammatory NF-κB target genes in RA, also contributes to the "IFN signature" in RA synovial macrophages.