New insights into the association between arthritis and overactive bladder in NHANES 2005-2020

Arthritis and overactive bladder (OAB) are both common diseases, but the association between them remains unclear. The aim of our research is to investigate the possible link with regard to arthritis and OAB. Our study's data was sourced from the National Health and Nutrition Examination Survey (NHANES) database from 2005 to 2020. The Overactive Bladder Symptom Score (OABSS) was used to diagnose OAB, while the health questionnaire was used to diagnose arthritis. This research utilized weighted logistic regression to evaluate the correlation between OAB and arthritis. To ensure the robustness of these results, subgroup analyses along with interaction tests were performed. Our research comprised 24,436 participants. After correcting for all covariates, we found a positive association between arthritis and OAB (OR = 1.37, 95% CI: 1.22, 1.54). Stratified by arthritis type, there was a positive association between osteoarthritis (OA) and OAB (OR = 1.40, 95% CI: 1.22, 1.62). Rheumatoid arthritis (RA) (OR = 1.20, 95% CI: 0.99, 1.46) and psoriatic arthritis (OR = 1.40, 95% CI: 0.75, 2.60) were not significantly correlated with OAB. This research demonstrated that arthritis was closely related to OAB. Additional research is required to confirm this association.

Helicobacter pylori and rheumatoid arthritis: Investigation of relation from traditional Chinese medicine

Rheumatoid arthritis (RA) is an autoimmune condition that predominantly affects synovial joints, manifesting with joint swelling, pain, and stiffness. In advanced stages, unchecked inflammation can inflict damage on bone and cartilage, resulting in disabilities and deformities of the joints. Additionally, systemic and extra-articular complications may arise due to the consequences of uncontrolled inflammation. Helicobacter pylori (H. pylori) is one of the most prevalent chronic bacterial infections in humans. This microorganism is a spiral-shaped, flagellated, microaerophilic gram-negative bacterium. Prolonged exposure leads to the activation of the immune system, with infected gastric mucosa epithelial cells continuously producing cytokines. This production, in turn, triggers the generation of antibodies as well as T Helper 1 and T Helper 2 effector T cells. The persistent antigenic stimulation resulting from H. pylori infection could lead to the progression of autoimmune diseases. Numerous clinical and pharmacological trials have illustrated the efficacy of traditional Chinese medicine against H. pylori. This review aims to delve into the connection between H. pylori and rheumatoid arthritis so as understand the pathogenesis. The concluding section of this review explores the interplay of Chinese medicine and Helicobacter pylori concerning rheumatoid arthritis.

IL-17 in skin infections and homeostasis

Interleukin (IL) 17 is a proinflammatory cytokine belonging to a structurally related group of cytokines known as the IL-17 family. It has been profoundly studied for its contribution to the pathology of autoimmune diseases. However, it also plays an important role in homeostasis and the defense against extracellular bacteria and fungi. IL-17 is important for epithelial barriers, including the skin, where some of its cellular targets reside. Most of the research work on IL-17 has focused on its effects in the skin within the context of autoimmune diseases or sterile inflammation, despite also having impact on other skin conditions. In recent years, studies on the role of IL-17 in the defense against skin pathogens and in the maintenance of skin homeostasis mediated by the microbiota have grown in importance. Here we review and discuss the cumulative evidence regarding the main contribution of IL-17 in the maintenance of skin integrity as well as its protective or pathogenic effects during some skin infections.

IL-17 family cytokines in inflammatory or autoimmune skin diseases

As potent pro-inflammatory mediators, IL-17 family cytokines play crucial roles in the pathogenesis of various inflammatory and autoimmune skin disorders. Although substantial progress has been achieved in understanding the pivotal role of IL-17A signaling in psoriasis, leading to the development of highly effective biologics, the functions of other IL-17 family members in inflammatory or autoimmune skin diseases remain less explored. In this review, we provide a comprehensive overview of IL-17 family cytokines and their receptors, with a particular focus on the recent advancements in identifying cellular sources, receptors and signaling pathways regulated by these cytokines. At the end, we discuss how the aberrant functions of IL-17 family cytokines contribute to the pathogenesis of diverse inflammatory or autoimmune skin diseases.

Rheumatoid arthritis-associated complications during pregnancy and its effect on offspring: comprehensive review

This study comprehensively explores the complexities of rheumatoid arthritis during pregnancy and its impact on offspring. Through an extensive review of existing literature, we investigate maternal and fetal risks, including adverse pregnancy outcomes and developmental issues in offspring. Utilizing reputable databases such as PubMed, Google Scholar, and Science Direct, we meticulously examined studies exploring the connection between rheumatoid arthritis and pregnancy complications, with a focus on outcomes for offspring. We excluded studies lacking sufficient data or peer review. Synthesizing findings from selected studies, we identified common themes and patterns, presenting results in a clear, organized manner. Our examination reveals a heightened likelihood of preterm birth and preeclampsia among pregnant individuals with rheumatoid arthritis, often correlated with disease activity. Furthermore, we highlight the impact on fetal and neonatal outcomes, such as low birth weight, underscoring the importance of meticulous disease management throughout pregnancy. Balancing the necessity of disease-modifying agents with potential risks, and consideration of medication safety is paramount. A multidisciplinary approach involving rheumatologists and obstetricians is crucial for optimizing outcomes. In conclusion, this synthesis underscores the nuanced challenges of rheumatoid arthritis in pregnancy. A comprehensive understanding and personalized, multidisciplinary approach to an organization is essential for informed decision-making in clinical practice. Our review contributes to ongoing discourse, providing insights for enhanced patient care and guiding future research endeavors.

N-demethylsinomenine metabolite and its prototype sinomenine activate mast cells via MRGPRX2 and aggravate anaphylaxis

Sinomenine hydrochloride (SH) is commonly used in the treatment of rheumatoid arthritis. It activates mast cells and induces anaphylaxis in the clinical setting. Adverse drug reactions can be caused by activation of MAS-associated G protein-coupled receptor X2 (MRGPRX2) on mast cells. Because the ligand binding site of MRGPRX2 is easily contacted in dilute solvents, it can be activated by many opioid drug structures. N-Demethylsinomenine (M-3) has a similar chemical structure to that of the opioid scaffold and is a major metabolite of SH. We sought to clarify whether M-3 induces anaphylaxis synergistically with its prototype in a mouse model. Molecular docking computer simulations suggested a similar binding effect between M-3 and SH. M-3 was chemically synthesized and analyzed by surface plasmon resonance to reveal its affinity for MRGPRX2. Temperature monitoring, in vivo hindlimb swelling and exudation test, and in vitro mast cell degranulation test were used to explore the mechanism of MRGPrx2 mediated allergic reaction triggered by M-3. Reduced M-3-induced inflammation was evident in MrgprB2 (the ortholog of MRGPRX2) conditional (Cpa3-Cre/MrgprB2flox) knockout (MrgprB2-CKO) mice. Additionally, LAD2 human mast cells with MRGPRX2 knockdown showed reduced degranulation. M-3 activated LAD2 cells synergistically with SH as regulated by GRK2 signaling and IP3R/PLC/PKC/P38 molecular signaling pathways. The results indicate that the M-3 metabolite can activate mast cells synergistically with its prototype SH via MRGPRX2 and aggravate anaphylaxis. These findings provide important insights into drug safety.

Mast cells express IL17A, IL17F and RORC, are activated and persist with IL-17 production in resolved skin of patients with chronic plaque-type psoriasis

Little is known about IL-17 expression in psoriasis and the actual cellular source of IL-17 remains incompletely defined. We show that high numbers of IL-17 + mast cells persisted in resolved lesions after treatment (anti-IL-17A, anti-IL-23, UVB or topical dithranol) and correlated inversely with the time span in remission. IL-17 + mast cells were found in T cell-rich areas and often close to resident memory T cells (Trm) in active psoriasis and resolved lesional skin. Digital cytometry by deconvolution of RNA-seq data showed that activated mast cells were increased in psoriatic skin, while resting mast cells were almost absent and both returned to normal levels after treatment. When primary human skin mast cells were stimulated with T cell cytokines (TNFα, IL-22 and IFNγ), they responded by releasing more IL-17A, as measured by ELISA. In situ mRNA detection using padlock probes specific for transcript variants of IL17A, IL17F, and RORC (encoding the Th17 transcription factor RORγt) revealed positive mRNA signals for IL17A, IL17F, and RORCin tryptase + cells, demonstrating that mast cells have the transcriptional machinery to actively produce IL-17. Mast cells thus belong to the center of the IL-23/IL-17 axis and high numbers of IL-17 + mast cells predict an earlier disease recurrence.

Role of Bioactive Compounds, Novel Drug Delivery Systems, and Polyherbal Formulations in the Management of Rheumatoid Arthritis

Rheumatoid Arthritis (RA) is an autoimmune disorder that generally causes joint synovial inflammation as well as gradual cartilage and degenerative changes, resulting in progressive immobility. Cartilage destruction induces synovial inflammation, including synovial cell hyperplasia, increased synovial fluid, and synovial pane development. This phenomenon causes articular cartilage damage and joint alkalosis. Traditional medicinal system exerts their effect through several cellular mechanisms, including inhibition of inflammatory mediators, oxidative stress suppression, cartilage degradation inhibition, increasing antioxidants and decreasing rheumatic biomarkers. The medicinal plants have yielded a variety of active constituents from various chemical categories, including alkaloids, triterpenoids, steroids, glycosides, volatile oils, flavonoids, lignans, coumarins, terpenes, sesquiterpene lactones, anthocyanins, and anthraquinones. This review sheds light on the utilization of medicinal plants in the treatment of RA. It explains various phytoconstituents present in medicinal plants and their mechanism of action against RA. It also briefs about the uses of polyherbal formulations (PHF), which are currently in the market and the toxicity associated with the use of medicinal plants and PHF, along with the limitations and research gaps in the field of PHF. This review paper is an attempt to understand various mechanistic approaches employed by several medicinal plants, their possible drug delivery systems and synergistic effects for curing RA with minimum side effects.

Aberrant expression of interleukin-17A in mast cells contributes to the pathogenesis of hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) significantly diminishes the quality of life for patients. Delayed diagnosis represents a significant challenge in effectively managing HS.

OBJECTIVES

To identify and characterize the key mediator in HS.

METHODS

Bioinformatic transcriptomic analysis was applied to identify potential candidates contributing to the disease process of HS. Skin samples from 40 patients with HS, four with psoriasis and 29 with normal skin were included. The expression of interleukin (IL)-17A was evaluated and compared among samples of normal skin, psoriatic skin and skin from different stages of HS by immunohistochemistry or dual-colour immunofluorescence. In vitro experiments and RNA sequencing analysis were also conducted to validate the expression of IL-17A and its pathogenic effect in HS.

RESULTS

Transcriptomic database analyses identified IL-17 signalling as a potential contributor to HS. In HS, the predominant IL-17A+ cell population was identified as mast cells. IL-17A+ mast-cell density was significantly elevated in HS, especially in samples with advanced Hurley stages, compared with normal skin and psoriasis samples. The close contact between IL-17A+ mast cells and IL-17 receptor A (IL-17RA)-expressing keratinocytes was demonstrated, along with the significant effects of IL-17A on keratinocyte cell proliferation and HS pathogenic gene expression. Treatment with biologics (brodalumab or adalimumab) reduced the severity of the disease and the number of IL-17A+ mast cells in affected tissues.

CONCLUSIONS

The presence of high-density IL-17A+ mast cells may serve as a valuable pathological marker for diagnosing HS. Moreover, developing therapeutic drugs targeting IL-17A+ mast cells may provide a new approach to treating HS.

Influence of Helicobacter pylori infection on risk of rheumatoid arthritis: a nationwide population-based study

The relationship between Helicobacter pylori infection and rheumatoid arthritis has been investigated, but the results remain controversial. This study aims to determine the association between the two diseases via a 17-year retrospective cohort study. Using the National Health Insurance Research Database, a nationwide population based in Taiwan, we identified 97,533 individuals with H. pylori infection and matched controls between 2000 and 2017 using propensity score matching at a 1:1 ratio. The adjusted hazard ratio of rheumatoid arthritis was determined by multiple Cox regression. The incidence rate of rheumatoid arthritis was 1.28 per 10,000 person-months in the H. pylori cohort, with a higher risk compared to the control group. In the < 30 years old subgroup, the risk was highest, especially in women < 30 years old with H. pylori infection. Patients with < 1 year follow-up showed 1.58 times higher susceptibility to rheumatoid arthritis. Individuals with follow-ups of 1-5 years and over 5 years demonstrated 1.43 and 1.44 times higher risks of rheumatoid arthritis, respectively. Our study showed H. pylori infection was associated with the development of rheumatoid arthritis. Clinicians should note higher risk, especially < 30 years old. More research needed to understand underlying mechanism.

Mast Cell Involvement in the Pathogenesis of Selected Musculoskeletal Diseases

In recent years, there has been a noteworthy revival of interest in the function of mast cells (MCs) in the human body. It is now acknowledged that MCs impact a wide array of processes beyond just allergies, leading to a shift in research direction. Unfortunately, some earlier conclusions were drawn from animal models with flawed designs, particularly centered around the receptor tyrosine kinase (Kit) pathway. Consequently, several subsequent findings may have been unreliable. Thus, what is now required is a re-examination of these earlier findings. Nevertheless, the remaining data are fascinating and hold promise for a better comprehension of numerous diseases and the development of more effective therapies. As the field continues to progress, many intriguing issues warrant further investigation and analysis. For instance, exploring the bidirectional action of MCs in rheumatoid arthritis, understanding the extent of MCs' impact on symptoms associated with Ehlers-Danlos syndrome, and unraveling the exact role of the myofibroblast-mast cell-neuropeptides axis in the joint capsule during post-traumatic contractures are all captivating areas for exploration. Hence, in this review, we summarize current knowledge regarding the influence of MCs on the pathogenesis of selected musculoskeletal diseases, including rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, gout, muscle and joint injuries, tendinopathy, heterotopic ossification, and Ehlers-Danlos syndrome. We believe that this review will provide in-depth information that can guide and inspire further research in this area.

CXCR3 antagonist NBI-74330 mitigates joint inflammation in Collagen-Induced arthritis model in DBA/1J mice

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by uncontrolled synovial proliferation, pannus formation, cartilage injury, and bone destruction. We used the CXCR3-specific antagonist NBI-74330 to block T-cell-mediated signaling in a DBA/1J mouse model of collagen-induced arthritis (CIA). After CIA induction, DBA/1J mice were treated with NBI-74330 (100 mg/kg) daily from day 21 until day 34 and evaluated for arthritic score and histopathological changes. Furthermore, using flow cytometry, we investigated the effects of NBI-74330 on Th1 (IFN-γ, TNF-α, T-bet, STAT4, Notch-3, and RANKL), Th17 (IL-21, IL-17A, STAT3, and RORγt), and Th22 (IL-22) cells in splenic CD4⁺ and CXCR3⁺T-cells. We also used RT-PCR to assess the effect of mRNA levels of IFN-γ, TNF-α, T-bet, RANKL, IL-17A, RORγt, and IL-22 in knee tissues. The IFN-γ, TNF-α, and IL-17A serum protein levels were measured using ELISA. Compared to vehicle-treated CIA mice, the severity of arthritic scores and histological severity of inflammation decreased significantly in NBI-74330-treated CIA mice. Moreover, compared to vehicle-treated CIA mice, the percentages of CD4⁺IFN-γ⁺, CD4⁺TNF-α⁺, CD4⁺T-bet⁺, CD4⁺STAT4⁺, CD4⁺Notch-3⁺, CXCR3⁺IFN-γ⁺, CXCR3⁺TNF-α⁺, CXCR3⁺T-bet⁺, CXCR3⁺STAT4⁺, CXCR3⁺Notch-3⁺, CD4⁺RANKL⁺, CD4⁺IL-21⁺, CD4⁺IL-17A⁺, CD4⁺STAT3⁺, CD4⁺RORγt⁺, and CD4⁺IL-22⁺ cells decreased in NBI-74330-treated CIA mice. Furthermore, NBI-74330-treatment downregulated IFN-γ, TNF-α, T-bet, RANKL, STAT3, IL-17A, RORγt, and IL-22 mRNA levels. Serum IFN-γ, TNF-α, and IL-17A levels were significantly lower in NBI-74330-treated CIA mice than in vehicle-treated CIA mice. This study demonstrates the antiarthritic effects of NBI-74330 in CIA mice. Therefore, these data suggest that NBI-74330 could be considered a potential RA treatment.

Interleukin 26 Induces Macrophage IL-9 Expression in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease with chronic inflammation, bone erosion, and joint deformation. Synovial tissue in RA patients is full of proinflammatory cytokines and infiltrated immune cells, such as T help (Th) 9, Th17, macrophages, and osteoclasts. Recent reports emphasized a new member of the interleukin (IL)-10 family, IL-26, an inducer of IL-17A that is overexpressed in RA patients. Our previous works found that IL-26 inhibits osteoclastogenesis and conducts monocyte differentiation toward M1 macrophages. In this study, we aimed to clarify the effect of IL-26 on macrophages linking to Th9 and Th17 in IL-9 and IL-17 expression and downstream signal transduction. Murine and human macrophage cell lines and primary culture cells were used and stimulated by IL26. Cytokines expressions were evaluated by flow cytometry. Signal transduction and transcription factors expression were detected by Western blot and real time-PCR. Our results show that IL-26 and IL-9 colocalized in macrophage in RA synovium. IL-26 directly induces macrophage inflammatory cytokines IL-9 and IL-17A expression. IL-26 increases the IL-9 and IL-17A upstream mechanisms IRF4 and RelB expression. Moreover, the AKT-FoxO1 pathway is also activated by IL-26 in IL-9 and IL-17A expressing macrophage. Blockage of AKT phosphorylation enhances IL-26 stimulating IL-9-producing macrophage cells. In conclusion, our results support that IL-26 promotes IL-9- and IL-17-expressing macrophage and might initiate IL-9- and IL-17-related adaptive immunity in rheumatoid arthritis. Targeting IL-26 may a potential therapeutic strategy for rheumatoid arthritis or other IL-9 plus IL-17 dominant diseases.

IL-17A expression by both T cells and non-T cells contribute to HSV-IL-2-induced CNS demyelination

Previously we reported that a recombinant HSV-1 expressing murine IL-2 (HSV-IL-2) causes CNS demyelination in different strains of mice and in a T cell-dependent manner. Since TH17 cells have been implicated in CNS pathology, in the present study, we looked into the effects of IL-17A-/- and three of its receptors on HSV-IL-2-induced CNS demyelination. IL-17A-/- mice did not develop CNS demyelination, while IL-17RA-/-, IL-17RC-/-, IL-17RD-/- and IL-17RA-/-RC-/- mice developed CNS demyelination. Adoptive transfer of T cells from wild-type (WT) mice to IL-17A-/- mice or T cells from IL-17A-/- mice to Rag-/- mice induced CNS demyelination in infected mice. Adoptive T cell experiments suggest that both T cells and non-T cells expressing IL-17A contribute to HSV-IL-2-induced CNS demyelination with no difference in the severity of demyelination between the two groups of IL-17A producing cells. IL-6, IL-10, or TGFβ did not contribute to CNS demyelination in infected mice. Transcriptome analysis between IL-17A-/- brain and spinal cord of infected mice with and without T cell transfer from WT mice revealed that "neuron projection extension involved in neuron projection guidance" and "ensheathment of neurons" pathways were associated with CNS demyelination. Collectively, the results indicate the importance of IL-17A in CNS demyelination and the possible involvement of more than three of IL-17 receptors in CNS demyelination.

Use of some bone-related cytokines as predictors for rheumatoid arthritis severity by neural network analysis

Background. Rheumatoid arthritis (RA) is characterized by synovial membrane inflammation that results in joint damage. Many earlier studies have measured cytokines for a better diagnosis of RA. In the present study, three bone biomarkers (osteopontin, Stromelysin-1 (MMP3), and vascular endothelial growth factor-A (VEGF)) are examined for their ability to estimate the severity of disease by using artificial neural network (NN) analysis and regression analysis. Methods: The study enrolled 87 RA patients and 44 healthy control subjects. The biomarkers were measured by the enzyme-linked immunosorbent assay (ELISA) technique. Disease Activity Score (28 joints) and C-reactive protein (CRP) (DAS28-CRP) was calculated by using (DAS28-CRP) calculator. The patients with DAS28-CRP5.1 are considered as having high disease activity (HDA). While patients group with DAS28-CRP5.1 are considered as moderate disease activity (MDA). The neural network (NN) analysis was used for the differentiation between groups. Results. Results showed that the most sensitive predictor for high disease activity (HDA) of RA is MMP3, followed by osteopontin and VEGF. These three biomarkers can differentiate significantly between HDA and moderate disease activity (MDA) with a relatively high size effect (Partial 2=0.323, p0.001). HDA group has a significantly higher MMP3, CRP, RF, and anti-citrullinated protein antibodies (ACPA) than the MDA group. Conclusions. The use of the NN analysis indicated that the measured biomarkers help predict the HDA state in RA patients. MMP3 and osteopontin are diagnostic biomarkers for the severity of RA disease and related to many disease-related characteristics with a sensitivity of 88.9% and specificity of 68.4%.

Two Epitope Regions Revealed in the Complex of IL-17A and Anti-IL-17A VHH Domain

Interleukin-17 (IL-17) is a cytokine produced by the Th17 cells. It is involved in chronic inflammation in patients with autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, and psoriasis. The antibodies targeting IL-17 and/or IL-17R are therapy tools for these diseases. Netakimab is an IL-17A-specific antibody containing a Lama glama V_HH derivative domain and a VL variable domain. We have determined the crystal structure of the IL-17A-specific V_HH domain in complex with IL-17A at 2.85 Å resolution. Certain amino acid residues of the three complementary-determining regions of the V_HH domain form a network of solvent-inaccessible hydrogen bonds with two epitope regions of IL-17A. The β-turn of IL-17A, which forms the so-called epitope-1, appears to be the main region of IL-17A interaction with the antibody. Contacts formed by the IL-17A mobile C-terminal region residues (epitope-2) further stabilize the antibody-antigen complex.

Neutrophil breaching of the blood vessel pericyte layer during diapedesis requires mast cell-derived IL-17A

Neutrophil diapedesis is an immediate step following infections and injury and is driven by complex interactions between leukocytes and various components of the blood vessel wall. Here, we show that perivascular mast cells (MC) are key regulators of neutrophil behaviour within the sub-endothelial space of inflamed venules. Using confocal intravital microscopy, we observe directed abluminal neutrophil motility along pericyte processes towards perivascular MCs, a response that created neutrophil extravasation hotspots. Conversely, MC-deficiency and pharmacological or genetic blockade of IL-17A leads to impaired neutrophil sub-endothelial migration and breaching of the pericyte layer. Mechanistically, identifying MCs as a significant cellular source of IL-17A, we establish that MC-derived IL-17A regulates the enrichment of key effector molecules ICAM-1 and CXCL1 in nearby pericytes. Collectively, we identify a novel MC-IL-17A-pericyte axis as modulator of the final steps of neutrophil diapedesis, with potential translational implications for inflammatory disorders driven by increased neutrophil diapedesis.

Mast Cells and Interleukins

Mast cells play a critical role in inflammatory diseases and tumor growth. The versatility of mast cells is reflected in their ability to secrete a wide range of biologically active cytokines, including interleukins, chemokines, lipid mediators, proteases, and biogenic amines. The aim of this review article is to analyze the complex involvement of mast cells in the secretion of interleukins and the role of interleukins in the regulation of biological activities of mast cells.

Integrative Analysis of Transcriptome-Wide Association Study and Gene-Based Association Analysis Identifies In Silico Candidate Genes Associated with Juvenile Idiopathic Arthritis

Genome-wide association study (GWAS) of Juvenile idiopathic arthritis (JIA) suffers from low power due to limited sample size and the interpretation challenge due to most signals located in non-coding regions. Gene-level analysis could alleviate these issues. Using GWAS summary statistics, we performed two typical gene-level analysis of JIA, transcriptome-wide association studies (TWAS) using FUnctional Summary-based ImputatiON (FUSION) and gene-based analysis using eQTL Multi-marker Analysis of GenoMic Annotation (eMAGMA), followed by comprehensive enrichment analysis. Among 33 overlapped significant genes from these two methods, 11 were previously reported, including TYK2 (PFUSION = 5.12 × 10-6, PeMAGMA = 1.94 × 10-7 for whole blood), IL-6R (PFUSION = 8.63 × 10-7, PeMAGMA = 2.74 × 10-6 for cells EBV-transformed lymphocytes), and Fas (PFUSION = 5.21 × 10-5, PeMAGMA = 1.08 × 10-6 for muscle skeletal). Some newly plausible JIA-associated genes are also reported, including IL-27 (PFUSION = 2.10 × 10-7, PeMAGMA = 3.93 × 10-8 for Liver), LAT (PFUSION = 1.53 × 10-4, PeMAGMA = 4.62 × 10-7 for Artery Aorta), and MAGI3 (PFUSION = 1.30 × 10-5, PeMAGMA = 1.73 × 10-7 for Muscle Skeletal). Enrichment analysis further highlighted 4 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and 10 Gene Ontology (GO) terms. Our findings can benefit the understanding of genetic determinants and potential therapeutic targets for JIA.

Morphological and Mechanical Characterization of Extracellular Vesicles and Parent Human Synoviocytes under Physiological and Inflammatory Conditions

The morphology of fibroblast-like synoviocytes (FLS) issued from the synovial fluid (SF) of patients suffering from osteoarthritis (OA), rheumatoid arthritis (RA), or from healthy subjects (H), as well as the ultrastructure and mechanical properties of the FLS-secreted extracellular vesicles (EV), were analyzed by confocal microscopy, transmission electron microscopy, atomic force microscopy, and tribological tests. EV released under healthy conditions were constituted of several lipid bilayers surrounding a viscous inner core. This "gel-in" vesicular structure ensured high mechanical resistance of single vesicles and good tribological properties of the lubricant. RA, and to a lesser extent OA, synovial vesicles had altered morphology, corresponding to a "gel-out" situation with vesicles surrounded by a viscous gel, poor mechanical resistance, and poor lubricating qualities. When subjected to inflammatory conditions, healthy cells developed phenotypes similar to that of RA samples, which reinforces the importance of inflammatory processes in the loss of lubricating properties of SF.

Contribution of pathogenic T helper 1 and 17 cells to bursitis and tenosynovitis in polymyalgia rheumatica

Background

Although polymyalgia rheumatica (PMR) is a very common rheumatic inflammatory disease, current insight into the pathobiology of PMR is limited and largely based on studies in blood. We investigated T helper 1 (TH1) and T helper 17 (TH17) cell responses in blood, synovial fluid and bursa tissue of patients with PMR.

Materials and methods

Blood samples were collected from 18 patients with new-onset PMR and 32 healthy controls. Synovial fluid was aspirated from the inflamed shoulder bursae or biceps tendon sheath of 13 patients. Ultrasound-guided biopsies of the subacromial-subdeltoid (SASD) bursa were obtained from 11 patients. T cells were examined by flow cytometry, immunohistochemistry and immunofluorescence staining.

Results

Besides an increase of TH17 (CD4+IL-17+IFN-γ-) cells and T cytotoxic 17 (TC17; CD8+IL-17+IFN-γ-) cells, no other major changes were noted in the circulating T cell compartment of patients with PMR. Absolute numbers of CD4+ and CD8+ T cells were similar in blood and synovial fluid of patients with PMR. Synovial fluid T cells showed an effector-memory (CD45RO+CCR7-) phenotype. Percentages of TH1 (CD4+IFN-γ+IL-17-) cells and TH1/TH17 (CD4+IFN-γ+IL-17+) cells, but not TH17 or TC17 cells, were increased in the synovial fluid. Bursa tissue biopsies contained a small number of T cells, which were mostly CD8 negative. The majority of bursa tissue T cells produced IFN-γ but not IL-17. For comparison, B cells were scarcely detected in the bursa tissue.

Conclusion

Although the circulating TH17 cell pool is expanded in patients with PMR, our findings indicate that TH1 cells are involved in the inflammation of bursae and tendon sheaths in this condition. Our study points towards the TH1 cell pathway as a potential target for therapy in PMR.

Immunomodulatory role of T helper cells in rheumatoid arthritis : a comprehensive research review

Rheumatoid arthritis (RA) is an autoimmune disease that involves T and B cells and their reciprocal immune interactions with proinflammatory cytokines. T cells, an essential part of the immune system, play an important role in RA. T helper 1 (Th1) cells induce interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α), and interleukin (IL)-2, which are proinflammatory cytokines, leading to cartilage destruction and bone erosion. Th2 cells primarily secrete IL-4, IL-5, and IL-13, which exert anti-inflammatory and anti-osteoclastogenic effects in inflammatory arthritis models. IL-22 secreted by Th17 cells promotes the proliferation of synovial fibroblasts through induction of the chemokine C-C chemokine ligand 2 (CCL2). T follicular helper (Tfh) cells produce IL-21, which is key for B cell stimulation by the C-X-C chemokine receptor 5 (CXCR5) and coexpression with programmed cell death-1 (PD-1) and/or inducible T cell costimulator (ICOS). PD-1 inhibits T cell proliferation and cytokine production. In addition, there are many immunomodulatory agents that promote or inhibit the immunomodulatory role of T helper cells in RA to alleviate disease progression. These findings help to elucidate the aetiology and treatment of RA and point us toward the next steps.

Cite this article: Bone Joint Res 2022;11(7):426–438.

Immunomodulation—What to Modulate and Why? Potential Immune Targets

Despite over 50 years of research into the immunology of periodontal disease, the precise mechanisms and the role of many cell types remains an enigma. Progress has been limited by the inability to determine disease activity clinically. Understanding the immunopathogenesis of periodontal disease however is fundamental if immunomodulation is to be used as a therapeutic strategy. It is important for the clinician to understand what could be modulated and why. In this context, potential targets include different immune cell populations and their subsets, as well as various cytokines. The aim of this review is to examine the role of the principal immune cell populations and their cytokines in the pathogenesis of periodontal disease and their potential as possible therapeutic targets.

Hypoxia-Inducible Factor-2 Alpha Regulates the Migration of Fibroblast-like Synoviocytes via Oxidative Stress-Induced CD70 Expression in Patients with Rheumatoid Arthritis

This study aimed to examine the role of CD70, which is highly expressed on fibroblast-like synoviocytes (FLS), in rheumatoid arthritis (RA) patients. FLS isolated from RA (n = 14) and osteoarthritis (OA, n = 4) patients were stimulated with recombinant interleukin-17 (IL-17; 5 ng/mL) and tumor necrosis factor alpha (TNF-α; 5 ng/mL) for 24 h. Expression of CD70, CD27/soluble CD27 (sCD27), and hypoxia-inducible factor-2 alpha (HIF-2α) was analyzed by RT-qPCR, flow cytometry, and ELISA assays, respectively. Reactive oxygen species (ROS) expression and cell migration were also examined. The HIF-2α inhibitor PT-2385 and CD70 inhibitor BU69 were used to specifically suppress these pathways. Stimulation with IL-17 and TNF-α significantly induced CD70 expression in RA FLS. Although the synovial fluids from patients with RA contained high levels of sCD27, surface expression of CD27, a ligand of CD70, was rarely detected in RA FLS. Cytokine-induced CD70 expression was significantly decreased following antioxidant treatment. Following HIF-2α inhibition, RA FLS had decreased expression of CD70 and ROS levels. Migration of RA FLS was also inhibited by inhibition of CD70 or HIF-2α. The surface expression of CD70 is regulated by HIF-2α and ROS levels and is a key contributor to cytokine-enhanced migration in RA FLS.

Acupuncture for Primary Dysmenorrhea: A Potential Mechanism from an Anti-Inflammatory Perspective

The low adverse effects of acupuncture for primary dysmenorrhea (PD), known as one of the most commonly reported gynecological debilitating conditions affecting women's overall health, have been thus far confirmed. Moreover, it has been increasingly recognized that inflammation is involved in such menstrual cramps, and recent studies have further shown that the anti-inflammatory effects of acupuncture are helpful in its control. This review portrays the role of inflammation in PD pathophysiology, provides evidence from clinical and animal studies on acupuncture for inflammation-induced visceral pain, and reflects on acupuncture-related therapies for dysmenorrhea with regard to their anti-inflammatory characteristics. Further research accordingly needs to be carried out to clarify the effects of acupuncture on proinflammatory factors in PD, particularly chemokines and leukocytes. Future studies on this condition from an anti-inflammatory perspective should be also performed in line with the notion of emphasizing stimulation modes to optimize the clinical modalities of acupuncture. Additionally, the effects and mechanism of more convenient self-healing approaches such as TENS/TEAS for PD should be investigated.

The protective effects of allopurinol against IL-17A-induced inflammatory response in mast cells

Rheumatoid arthritis (RA) is a common autoimmune disease in the elderly and it has been recently reported to be significantly associated with the activation of mast cells in joint tissues. IL-17A is a vital mediator that stimulates the activation of inflammation. Allopurinol is a classic agent for the suppression of uric acid production, recently reported to exert therapeutic effects on RA. In the present study, we investigated the regulatory effect of allopurinol against IL-17A-induced inflammatory response in mast cells and explored the potential mechanism of allopurinol on RA treatment. Firstly, we found that compared to normal synovium, IL-17A was significantly upregulated in the human RA synovium. IL-17A was used to stimulate an inflammatory state in mast cells in the absence or presence of allopurinol. We found that the production of inflammatory factors, PGE₂, and COX-2 was significantly elevated in IL-17A-treated mast cells, accompanied by the activation of the iNOS/NO axis and the elevated secretion of ROS. After treatment with allopurinol, the elevated inflammation, activated COX-2/PGE₂ and iNOS/NO axis, and oxidative stress were all dramatically alleviated. Mechanistically, the activated JNK/AP-1 and NF-κB pathways in IL-17A-treated mast cells were dramatically suppressed by the introduction of allopurinol. Taken together, our data reveal that allopurinol significantly alleviated the IL-17A-induced inflammatory response in mast cells.

Mast Cells as Important Regulators in Autoimmunity and Cancer Development

Mast cells are an essential part of the immune system and are best known as important modulators of allergic and anaphylactic immune responses. Upon activation, mast cells release a multitude of inflammatory mediators with various effector functions that can be both protective and damage-inducing. Mast cells can have an anti-inflammatory or pro-inflammatory immunological effect and play important roles in regulating autoimmune diseases including rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. Importantly, chronic inflammation and autoimmunity are linked to the development of specific cancers including pancreatic cancer, prostate cancer, colorectal cancer, and gastric cancer. Inflammatory mediators released from activated mast cells regulate immune responses and promote vascular permeability and the recruitment of immune cells to the site of inflammation. Mast cells are present in increased numbers in tissues affected by autoimmune diseases as well as in tumor microenvironments where they co-localize with T regulatory cells and T effector cells. Mast cells can regulate immune responses by expressing immune checkpoint molecules on their surface, releasing anti-inflammatory cytokines, and promoting vascularization of solid tumor sites. As a result of these immune modulating activities, mast cells have disease-modifying roles in specific autoimmune diseases and cancers. Therefore, determining how to regulate the activities of mast cells in different inflammatory and tumor microenvironments may be critical to discovering potential therapeutic targets to treat autoimmune diseases and cancer.

IL-17+ Mast Cell/T Helper Cell Axis in the Early Stages of Acne

Acne is a multifactorial disease driven by physiological changes occurring during puberty in the pilosebaceous unit (PSU) that leads to sebum overproduction and a dysbiosis involving notably Cutibacterium acnes. These changes in the PSU microenvironment lead to a shift from a homeostatic to an inflammatory state. Indeed, immunohistochemical analyses have revealed that inflammation and lymphocyte infiltration can be detected even in the infraclinical acneic stages, highlighting the importance of the early stages of the disease. In this study, we utilized a robust multi-pronged approach that included flow cytometry, confocal microscopy, and bioinformatics to comprehensively characterize the evolution of the infiltrating and resident immune cell populations in acneic lesions, beginning in the early stages of their development. Using a discovery cohort of 15 patients, we demonstrated that the composition of immune cell infiltrate is highly dynamic in nature, with the relative abundance of different cell types changing significantly as a function of clinical lesion stage. Within the stages examined, we identified a large population of CD69⁺ CD4⁺ T cells, several populations of activated antigen presenting cells, and activated mast cells producing IL-17. IL-17⁺ mast cells were preferentially located in CD4⁺ T cell rich areas and we showed that activated CD4⁺ T cells license mast cells to produce IL-17. Our study reveals that mast cells are the main IL-17 producers in the early stage of acne, underlying the importance of targeting the IL-17⁺ mast cell/T helper cell axis in therapeutic approaches.

Comparison of individual and combination treatments with naproxen, prednisolone and hydroxychloroquine to treat Complete Freund's Adjuvant induced arthritis

Aim of this study was to evaluate and compare the efficacy of anti-arthritic drugs (naproxen, prednisolone, and hydroxychloroquine) alone and in combination. The in vitro anti-arthritic activity was evaluated by stabilization of human erythrocytes (HRBCs) membrane assays. In vivo activity was carried out using Complete Freund's Adjuvant (CFA) induced arthritic model in Wistar rat. Individual and combination drugs were administered for 21 days in rats 8 days post inoculation with CFA (0.15 ml injected in right hind paw). Body weight and paw edema were measured at different intervals. Combination treatments exhibited more HRBC stabilization than individual treatments. All individual and combination treatments reduced the level of C-reactive protein (CRP), liver function enzymes, malondialdehyde, white blood cells and platelets, with the most pronounced activity exhibited by the combination of three drugs. The level of oxidative stress biomarkers (reduced glutathione, catalase, and superoxide dismutase), red blood cells, and hemoglobin were notably increased in all treatment groups in contrasts to diseased control rats. Histopathological evaluation of the paw showed that all the treatments had reduced (p < 0.05-0.001) the arthritic indices in contrasts to diseased control rats. The serum concentrations of TNF-α and PGE2 were provoked in diseased control rats but had been notably (p < 0.0001) restored by treatments with individual and combination drugs. It was also found that combination treatments, more precisely triple drug was remarkably effective in treating arthritis. It can be concluded that naproxen, prednisolone, and hydroxychloroquine effectively ameliorated the CFA-induced arthritis and were more effective in combination as compared to individual drug therapy probably due to reduction in oxidative stress and inflammatory markers. Moreover, two lower doses (half NPH/2 and one-third NPH/3) of triple combination therapy naproxen, prednisolone, and hydroxychloroquine (NPH) showed no significant difference in anti-arthritic effect as compared to the highest dose level of NPH.

Biomarkers for treatment change and radiographic progression in patients with rheumatoid arthritis in remission: a 5 year follow-up study

OBJECTIVE

To identify biomarkers of treatment change and radiographic progression in patients with RA under remission.

PATIENTS AND METHODS

RA patients in remission (DAS28-ESR <2.6) were selected and followed up for 5 years. An MRI of the dominant hand and an US assessment of knees/hands and serum levels of inflammation/angiogenesis biomarkers were performed at baseline and at 12th month. Synovial biopsies were obtained in patients with Power Doppler signal. Conventional radiographies of hands/feet were taken at baseline and after 5 years. Radiographic progression was defined as the change in the modified Sharp van der Heijde Score at 5 years >10.47 (small detectable change).

RESULTS

Sixty patients were included, 81.6% were ACPA+ and 45% were taking biological DMARDs. At baseline, 66.6% had Power Doppler signal. After 5 years, 73.3% of patients remained in remission. Change of therapy was performed in 20 patients (33.3%) and was associated with BMI [odds ratio (OR) 1.3, 95% CI: 1, 1.7], lack of biological DMARD therapy (OR 24.7, 95% CI: 2.3, 257.2), first-year progression of MRI erosions (OR 1.2, 95% CI: 1, 1.3) and calprotectin serum levels (OR 2.8, 95% CI: 1, 8.2). Radiographic progression occurred in six (10%) patients. These patients had higher first-year progression of MRI erosions (P =  0.03) and bone oedema (P = 0.04). Among 23 patients undergoing synovial biopsy, mast cell density was independently associated with clinical flares.

CONCLUSIONS

One-third of RA patients lost clinical remission and changed therapy throughout the 5 years of follow-up, which was independently associated with BMI, lack of biological DMARDs therapy and first-year progression of MRI erosion score and calprotectin serum levels. Significant radiographic progression was uncommon.

Chemokine Receptor 5 Antagonism Causes Reduction in Joint Inflammation in a Collagen-Induced Arthritis Mouse Model

Rheumatoid arthritis (RA) is a chronic inflammatory disease mainly affecting the synovial joints. A highly potent antagonist of C-C chemokine receptor 5 (CCR5), maraviroc (MVC), plays an essential role in treating several infectious diseases but has not yet been evaluated for its potential effects on RA development. This study focused on evaluating the therapeutic potential of MVC on collagen-induced arthritis (CIA) in DBA/1J mice. Following CIA induction, animals were treated intraperitoneally with MVC (50 mg/kg) daily from day 21 until day 35 and evaluated for clinical score and histopathological changes in arthritic inflammation. We further investigated the effect of MVC on Th9 (IL-9, IRF-4, and GATA3) and Th17 (IL-21R, IL-17A, and RORγT) cells, TNF-α, and RANTES in CD8+ T cells in the spleen using flow cytometry. We also assessed the effect of MVC on mRNA and protein levels of IL-9, IL-17A, RORγT, and GATA3 in knee tissues using RT-PCR and western blot analysis. MVC treatment in CIA mice attenuated the clinical and histological severity of inflammatory arthritis, and it substantially decreased IL-9, IRF4, IL-21R, IL-17A, RORγT, TNF-α, and RANTES production but increased GATA3 production in CD8+ T cells. We further observed that MVC treatment decreased IL-9, IL-17A, and RORγt mRNA and protein levels and increased those of GATA3. This study elucidates the capacity of MVC to ameliorate the clinical and histological signs of CIA by reducing pro-inflammatory responses, suggesting that MVC may have novel therapeutic uses in the treatment of RA.

Novel Strategies to Target Mast Cells in Disease

Mast cells (MCs) are versatile effector cells of the immune system, characterized by a large content of secretory granules containing a variety of inflammatory mediators. They are implicated in the host protection toward various external insults, but are mostly well known for their detrimental impact on a variety of pathological conditions, including allergic disorders such as asthma and a range of additional disease settings. Based on this, there is currently a large demand for therapeutic regimens that can dampen the detrimental impact of MCs in these respective pathological conditions. This can be accomplished by several strategies, including targeting of individual mediators released by MCs, blockade of receptors for MC-released compounds, inhibition of MC activation, limiting mast cell growth or by inducing mast cell apoptosis. Here, we review the currently available and emerging regimens to interfere with harmful mast cell activities in asthma and other pathological settings and discuss the advantages and limitations of such strategies.

Interleukin-17A Interweaves the Skeletal and Immune Systems

The complex crosstalk between the immune and the skeletal systems plays an indispensable role in the maintenance of skeletal homeostasis. Various cytokines are involved, including interleukin (IL)-17A. A variety of immune and inflammatory cells produces IL-17A, especially Th17 cells, a subtype of CD4⁺ T cells. IL-17A orchestrates diverse inflammatory and immune processes. IL-17A induces direct and indirect effects on osteoclasts. The dual role of IL-17A on osteoclasts partly depends on its concentrations and interactions with other factors. Interestingly, IL-17A exerts a dual role in osteoblasts in vitro. IL-17A is a bone-destroying cytokine in numerous immune-mediated bone diseases including postmenopausal osteoporosis (PMOP), rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondylarthritis (axSpA). This review will summarize and discuss the pathophysiological roles of IL-17A on the skeletal system and its potential strategies for application in immune-mediated bone diseases.

Neuroimmune connections between corticotropin-releasing hormone and mast cells: novel strategies for the treatment of neurodegenerative diseases

Corticotropin-releasing hormone is a critical component of the hypothalamic–pituitary–adrenal axis, which plays a major role in the body’s immune response to stress. Mast cells are both sensors and effectors in the interaction between the nervous and immune systems. As first responders to stress, mast cells can initiate, amplify and prolong neuroimmune responses upon activation. Corticotropin-releasing hormone plays a pivotal role in triggering stress responses and related diseases by acting on its receptors in mast cells. Corticotropin-releasing hormone can stimulate mast cell activation, influence the activation of immune cells by peripheral nerves and modulate neuroimmune interactions. The latest evidence shows that the release of corticotropin-releasing hormone induces the degranulation of mast cells under stress conditions, leading to disruption of the blood-brain barrier, which plays an important role in neurological diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, autism spectrum disorder and amyotrophic lateral sclerosis. Recent studies suggest that stress increases intestinal permeability and disrupts the blood-brain barrier through corticotropin-releasing hormone-mediated activation of mast cells, providing new insight into the complex interplay between the brain and gastrointestinal tract. The neuroimmune target of mast cells is the site at which the corticotropin-releasing hormone directly participates in the inflammatory responses of nerve terminals. In this review, we focus on the neuroimmune connections between corticotropin-releasing hormone and mast cells, with the aim of providing novel potential therapeutic targets for inflammatory, autoimmune and nervous system diseases.

IL-17A as a Potential Therapeutic Target for Patients on Peritoneal Dialysis

Chronic kidney disease (CKD) is a health problem reaching epidemic proportions. There is no cure for CKD, and patients may progress to end-stage renal disease (ESRD). Peritoneal dialysis (PD) is a current replacement therapy option for ESRD patients until renal transplantation can be achieved. One important problem in long-term PD patients is peritoneal membrane failure. The mechanisms involved in peritoneal damage include activation of the inflammatory and immune responses, associated with submesothelial immune infiltrates, angiogenesis, loss of the mesothelial layer due to cell death and mesothelial to mesenchymal transition, and collagen accumulation in the submesothelial compact zone. These processes lead to fibrosis and loss of peritoneal membrane function. Peritoneal inflammation and membrane failure are strongly associated with additional problems in PD patients, mainly with a very high risk of cardiovascular disease. Among the inflammatory mediators involved in peritoneal damage, cytokine IL-17A has recently been proposed as a potential therapeutic target for chronic inflammatory diseases, including CKD. Although IL-17A is the hallmark cytokine of Th17 immune cells, many other cells can also produce or secrete IL-17A. In the peritoneum of PD patients, IL-17A-secreting cells comprise Th17 cells, γδ T cells, mast cells, and neutrophils. Experimental studies demonstrated that IL-17A blockade ameliorated peritoneal damage caused by exposure to PD fluids. This article provides a comprehensive review of recent advances on the role of IL-17A in peritoneal membrane injury during PD and other PD-associated complications.

Current and novel therapeutic targets in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA), a multifactorial disease characterized by synovitis, cartilage destruction, bone erosion, and periarticular decalcification, finally results in impairment of joint function. Both genetic and environmental factors are risk factors in the development of RA. Unwanted side effects accompany most of the current treatment strategies, and around 20-40% of patients with RA do not clinically benefit from these treatments. The unmet need for new treatment options for RA has prompted research in the development of novel agents acting through physiologically and pharmacologically relevant targets. Here we discuss in detail three critical pathways, Janus kinase/signal transducer and activator of transcription (JAK/STAT), Th17, and hypoxia-inducible factor (HIF), and their roles as unique therapeutic targets in the field of RA. Some of the less developed but potential targets like nucleotide-binding and oligomerization domain-like receptor containing protein 3 (NLRP3) inflammasome and histone deacetylase 1 (HDAC1) are also discussed.

Activation of ocular surface mast cells promotes corneal neovascularization

PURPOSE

Mast cells, historically known for their effector function in the induction of allergic diseases, reside in all vascularized tissues of the body in particular proximity to blood and lymphatic vessels. As neighboring sentinel cells to blood vessels, mast cells have been associated with angiogenesis. Here we assess the direct contribution of mast cells to neovascularization at the ocular surface.

METHODS

Corneal neovascularization was induced by placing a single figure-of-eight intrastromal suture 1 mm from the limbus in mast cell-deficient (cKit^W-sh), C57BL/6, and Balb/c mice. Corneas were harvested at 6 h post-suture to quantify cKit⁺FcεR1⁺ mast cells using flow cytometry and tear wash was collected within 6 h to measure β-hexosaminidase and tryptase. Neovascularization was assessed using slit-lamp biomicroscope and immunohistochemistry analysis of corneas harvested on day 4 post-suture. To investigate the effects of mast cells on blood vessel growth, mast cells were co-cultured with vascular endothelial cells (VECs), and tube formation and proliferation of VECs were measured. 2% cromolyn was administered locally to inhibit mast cell activation in vivo.

RESULTS

Placement of corneal suture activates ocular surface mast cells, which infiltrate into the cornea adjacent to new vessels. Mast cell-deficient mice develop significantly fewer new vessels following suture placement. Mast cells directly promote VEC proliferation and tube formation, partly through secreting high levels of VEGF-A. Pharmacological inhibition of mast cell activation results in significantly less corneal neovascularization.

CONCLUSION

Our data demonstrate that ocular surface mast cells are critical to corneal neovascularization, suggesting mast cells as a potential therapeutic target in the treatment of corneal neovascularization.

RAR-related orphan receptor A: One gene with multiple functions related to migraine

Aims

RAR‐related orphan receptor (RORA) involves in regulation of several biological processes including inflammation and circadian rhythm that probably are involved in migraine pathophysiology. In the current study, the association between RORA rs11639084 and rs4774388 variants and susceptibility to migraine were investigated in a sample of Iranian migraine patients for the first time.

Methods

In a case‐control study including 400 participants, 200 migraineurs and 200 healthy controls, genotyping of RORA rs4774388 and rs11639084 polymorphisms was performed using tetra‐primer amplification refractory mutation system–polymerase chain reaction (TP‐ARMS‐PCR).

Results

The distribution of rs4774388 C/T and T/T genotypes differed significantly between the studied groups. Moreover, an association was observed between rs4774388 and migraine under the recessive mode of inheritance (P = 0.002; OR = 1.89.; CI = 1.25‐2.87). The distribution of rs11639084 alleles and genotypes was not significantly different between migraineurs and healthy controls.

Conclusion

Current results suggest RORA, as a molecular link, may explain inflammation and circadian rhythm dysfunction in migraine. Further studies in different ethnicities are required to confirm the function of RORA in migraine development.

Structural change of retinoic-acid receptor-related orphan receptor induced by binding of inverse-agonist: Molecular dynamics and ab initio molecular orbital simulations

To elucidate structural changes in the retinoic acid receptor-related orphan receptor gamma (RORγt) induced by the binding of an agonist or an inverse agonist, we conducted molecular dynamics (MD) simulations in explicit water. In addition, ab initio fragment molecular orbital calculations were carried out for certain characteristic structures obtained from the MD simulations to reveal important interactions between the amino acid residues of RORγt, and to distinguish the different effects in the binding of an agonist and an inverse agonist on the structure of RORγt. The results elucidate that the hydrogen bond between His479 of helix11 (H11) and Tyr502 of helix12 (H12) is important to keep the H12 conformation in the agonist-bound RORγt. In contrast, in the inverse-agonist-bound RORγt, the side chain of His479 rotates, significantly weakening the interaction between His479 and Tyr502, leading to a conformational change in H12. Therefore, the present molecular simulations clearly indicate that the conformational change in the side chain of His479 in the inverse-agonist-bound RORγt is the main reason for the H12 destabilization induced by the binding of the inverse agonist. Such a conformational change does not occur on the binding of the agonist in RORγt, owing to the strong hydrogen bond between His479 and Tyr502.

Role of TH17 Responses in Increasing Herpetic Keratitis in the Eyes of Mice Infected with HSV-1

Purpose

T_H17 cells play an important role in host defense and autoimmunity yet very little is known about the role of IL17 in herpes simplex virus (HSV)-1 infectivity. To better understand the relationship between IL17 and HSV-1 infection, we assessed the relative impact of IL17A-deficiency and deficiency of its receptors on HSV-1 responses in vivo.

Methods

We generated IL17RA^−/− and IL17RA^−/−RC^−/− mice in-house and infected them along with IL17A^−/− and IL17RC^−/− mice in the eyes with 2 × 10⁵ PFU/eye of wild type (WT) HSV-1 strain McKrae. WT C57BL/6 mice were used as control. Virus replication in the eye, survival, corneal scarring (CS), angiogenesis, levels of latency-reactivation, and levels of CD8 and exhaustion markers (PD1, TIM3, LAG3, CTLA4, CD244, and CD39) in the trigeminal ganglia (TG) of infected mice were determined on day 28 postinfection.

Results

No significant differences in virus replication in the eye, survival, latency, reactivation, and exhaustion markers were detected among IL17A^−/−, IL17RA^−/−, IL17RC^−/−, IL17RA^−/−RC^−/−, and WT mice. However, mice lacking IL17 had significantly less CS and angiogenesis than WT mice. In addition, angiogenesis levels in the absence of IL17RC and irrespective of the absence of IL17RA were significantly less than in IL17A- or IL17RA-deficient mice.

Conclusions

Our results suggest that the absence of IL17 protects against HSV-1-induced eye disease, but has no role in protecting against virus replication, latency, or reactivation. In addition, our data provide rationale for blocking IL17RC function rather than IL17A or IL17RA function as a key driver of HSV-1-induced eye disease.

The effect of nicotinamide adenine dinucleotide phosphate oxidase 4 on migration and invasion of fibroblast-like synoviocytes in rheumatoid arthritis

Background

Reactive oxygen species (ROS) regulate the migration and invasion of fibroblast-like synoviocytes (FLS), which are key effector cells in rheumatoid arthritis (RA) pathogenesis. Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) induces ROS generation and, consequently, enhances cell migration. Despite the important interrelationship between RA, FLS, and ROS, the effect of NOX4 on RA pathogenesis remains unclear.

Methods

FLS isolated from RA (n = 5) and osteoarthritis (OA, n = 5) patients were stimulated with recombinant interleukin 17 (IL-17; 10 ng/ml) and tumor necrosis factor alpha (TNF-α; 10 ng/ml) for 1 h. Cell migration, invasion, adhesion molecule expression, vascular endothelial growth factor (VEGF) secretion, and ROS expression were examined. The mRNA and protein levels of NOX4 were analyzed by RT-qPCR and western blotting, respectively. The NOX4 inhibitor GLX351322 and NOX4 siRNA were used to inhibit NOX4 to probe the effect of NOX4 on these cellular processes.

Results

Migration of RA FLS was increased 2.48-fold after stimulation with IL-17 and TNF-α, while no difference was observed for OA FLS. ROS expression increased in parallel with invasiveness of FLS following cytokine stimulation. When the expression of NOX was examined, NOX4 was significantly increased by 9.73-fold in RA FLS compared to unstimulated FLS. Following NOX4 inhibition, cytokine-induced vascular cell adhesion molecule 1 (VCAM1), VEGF, and migration and invasion capacity of RA FLS were markedly decreased to unstimulated levels.

Conclusion

NOX4 is a key contributor to cytokine-enhanced migration and invasion via modulation of ROS, VCAM1, and VEGF in RA FLS.

Anti-inflammatory and immune-regulatory cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by a failure of spontaneous resolution of inflammation. Although the pro-inflammatory cytokines and mediators that trigger RA have been the focus of intense investigations, the regulatory and anti-inflammatory cytokines responsible for the suppression and resolution of disease in a context-dependent manner have been less well characterized. However, knowledge of the pathways that control the suppression and resolution of inflammation in RA is clinically relevant and conceptually important for understanding the pathophysiology of the disease and for the development of treatments that enable long-term remission. Cytokine-mediated processes such as the activation of T helper 2 cells by IL-4 and IL-13, the resolution of inflammation by IL-9, IL-5-induced eosinophil expansion, IL-33-mediated macrophage polarization, the production of IL-10 by regulatory B cells and IL-27-mediated suppression of lymphoid follicle formation are all involved in governing the regulation and resolution of inflammation in RA. By better understanding these immune-regulatory signalling pathways, new therapeutic strategies for RA can be envisioned that aim to balance and resolve, rather than suppress, inflammation.

GM-CSF drives dysregulated hematopoietic stem cell activity and pathogenic extramedullary myelopoiesis in experimental spondyloarthritis

Dysregulated hematopoiesis occurs in several chronic inflammatory diseases, but it remains unclear how hematopoietic stem cells (HSCs) in the bone marrow (BM) sense peripheral inflammation and contribute to tissue damage in arthritis. Here, we show the HSC gene expression program is biased toward myelopoiesis and differentiation skewed toward granulocyte-monocyte progenitors (GMP) during joint and intestinal inflammation in experimental spondyloarthritis (SpA). GM-CSF-receptor is increased on HSCs and multipotent progenitors, favoring a striking increase in myelopoiesis at the earliest hematopoietic stages. GMP accumulate in the BM in SpA and, unexpectedly, at extramedullary sites: in the inflamed joints and spleen. Furthermore, we show that GM-CSF promotes extramedullary myelopoiesis, tissue-toxic neutrophil accumulation in target organs, and GM-CSF prophylactic or therapeutic blockade substantially decreases SpA severity. Surprisingly, besides CD4+ T cells and innate lymphoid cells, mast cells are a source of GM-CSF in this model, and its pathogenic production is promoted by the alarmin IL-33.

Roles of mast cells in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory arthritis, and the complex interaction and activation of innate and adaptive immune cells are involved in RA pathogenesis. Mast cells (MCs) are one of the tissue-resident innate immune cells, and they contribute to RA pathogenesis. In the present review, the evidence of the pathologic role of MC in RA is discussed based on human and animal data. In addition, the potential role of MC in RA pathogenesis and the research area that should be focused on in the future are suggested.

Microbiota-Dependent Involvement of Th17 Cells in Murine Models of Inflammatory Arthritis

Objective

Intestinal microbiota are associated with the development of inflammatory arthritis. The aim of this study was to dissect intestinal mucosal immune responses in the preclinical phase of arthritis and determine whether the presence of Th17 cells, beyond involvement of the cytokine interleukin‐17 (IL‐17), is required for arthritis development, and whether the involvement of Th17 cells in arthritis depends on the composition of the host microbiota.

Methods

Mucosal T cell production of IL‐17, interferon‐γ, tumor necrosis factor α (TNFα), IL‐22, and granulocyte–macrophage colony‐stimulating factor (GM‐CSF) was analyzed by flow cytometry and Luminex assay before arthritis onset in mice immunized to develop collagen‐induced arthritis (CIA). Pathogenic features of arthritis in mice with CIA and mice with antigen‐induced arthritis were compared between Th17 cell–deficient (CD4‐Cre⁺Rorc^flox/flox) and Th17 cell–sufficient (CD4‐Cre⁻Rorc^flox/flox) mice. In addition, the impact of intestinal microbiota on the Th17 cell dependence of CIA was assessed.

Results

Lamina propria CD4 T cells were activated before the onset of arthritis in mice with CIA, with marked up‐regulation of several cytokines, including IL‐17A, TNFα, and GM‐CSF. CD4‐Cre⁺Rorc^flox/flox mice showed a specific reduction in intestinal mucosal levels of Th17 cells and partially reduced levels of IL‐17–producing CD8 T cells. However, total levels of IL‐17A, mostly produced by γδ T cells and neutrophils, were unaffected. The severity of arthritis was significantly reduced in Th17 cell–deficient mice, suggesting that Th17 cells have additional, IL‐17A–independent roles in inflammatory arthritis. Accordingly, antigen‐stimulated T cells from Th17 cell–deficient mice produced less IL‐17A, IL‐17F, and GM‐CSF. Importantly, the dependence of CIA on the involvement of Th17 cells was mitigated in the presence of an alternative microbiome.

Conclusion

These data from murine models suggest that activation of mucosal immunity precedes the development of arthritis, and also that Th17 cells have a microbiota‐dependent role in arthritis. Therefore, a microbiome‐guided stratification of patients might improve the efficacy of Th17‐targeted therapies.

Endogenous stimulation is responsible for the high frequency of IL-17A-producing neutrophils in patients with rheumatoid arthritis

Background

Neutrophils play an important role in the pathogenesis of rheumatoid arthritis (RA). It has recently been reported that in addition to T helper (Th) 17 cells, other cells, including neutrophils, produce IL-17A, an important inflammatory cytokine involved in the pathogenesis of RA. The purpose of this study was to examine the presence of interleukin 17A-producing neutrophils in patients with RA.

Methods

We performed a cross-sectional study including 106 patients with RA and 56 healthy individuals. Whole peripheral blood cells were analyzed by flow cytometry to identify CD66b+ CD177+ IL-17A+ neutrophils and CD3+ CD4+ IL-17A+ T cells. Serum levels of IL-17A and IL-6 were measured by means of cytometry bead array (CBA). In purified neutrophils, mRNA levels of IL-17 and RORγ were measured by RT-PCR. In addition, purified neutrophils from patients and healthy controls were stimulated with the cytokines IL-6 and IL-23 to evaluate differences in their capacity to produce IL-17A.

Results

Neutrophils from RA patients expressed IL-17 and RORγ mRNA. Consequently, these cells also expressed IL-17A. Serum IL-17A levels but not Th17 cell numbers were increased in RA patients. Neutrophils positive for cytoplasmic IL-17A were more abundant in patients with RA (mean 1.2 ± 3.18%) than in healthy individuals (mean 0.07 ± 0.1%) (p < 0.0001). Although increased IL-17A+ neutrophil numbers were present in RA patients regardless of disease activity (mean 6.5 ± 5.14%), they were more frequent in patients with a more recent diagnosis (mean time after disease onset 3.5 ± 4.24 years). IL-6 and IL-23 induced the expression of RORγ but failed to induce IL-17A expression by neutrophils from RA patients and healthy individuals after a 3 h stimulation.

Conclusion

IL-17A-producing neutrophils are increased in some RA patients, which are not related to disease activity but have an increased frequency in patients with recent-onset disease. This finding suggests that IL-17A-producing neutrophils play an early role in the development of RA.

Electronic supplementary material

The online version of this article (10.1186/s13223-019-0359-9) contains supplementary material, which is available to authorized users.

T helper cell subpopulations repertoire in peripheral blood and its correlation with sex of newly diagnosed arthritis patients: A gender based study

Rheumatoid arthritis (RA) is an inflammatory autoimmune disorder. Autoreactive T cells play a very significant role in the pathogenesis of RA. However, the exact mechanisms of disease severity and pathogenesis are poorly understood. We attempted to correlate T-helper cell activities with sexes of newly diagnosed patients with RA. The patients were divided based on their sex and disease severity. Examination of the expression of various factors using quantitative real-time PCR and FACS analysis of peripheral blood mononuclear cells revealed that T-bet, ROR-γt, Foxp3, and the level of cytokines associated with Th1 cells were almost identical among male and female patients with RA. Interestingly, there was a high correlation between Th17 expression and disease severity in female patients with RA. In general, there was no significant correlation between Th1 cell population and the disease severity in newly diagnosed patients with RA. In contrast, the frequency of both Th17 and Treg cells was higher in patients with more severe disease. The results suggested that, in patients with RA, the T-helper cell balance within peripheral blood was skewed towards the Th17 and Treg phenotypes. Besides Th17- and Treg-associated cytokines, elevated expression of IL-27/IL-23 cytokines might also be responsible for increased disease severity in female patients with RA.

Mast Cells, Angiogenesis and Lymphangiogenesis in Human Gastric Cancer

Gastric cancer is diagnosed in nearly one million new patients each year and it remains the second leading cause of cancer-related deaths worldwide. Although gastric cancer represents a heterogeneous group of diseases, chronic inflammation has been shown to play a role in tumorigenesis. Cancer development is a multistep process characterized by genetic and epigenetic alterations during tumour initiation and progression. The stromal microenvironment is important in maintaining normal tissue homeostasis or promoting tumour development. A plethora of immune cells (i.e., lymphocytes, macrophages, mast cells, monocytes, myeloid-derived suppressor cells, Treg cells, dendritic cells, neutrophils, eosinophils, natural killer (NK) and natural killer T (NKT) cells) are components of gastric cancer microenvironment. Mast cell density is increased in gastric cancer and there is a correlation with angiogenesis, the number of metastatic lymph nodes and the survival of these patients. Mast cells exert a protumorigenic role in gastric cancer through the release of angiogenic (VEGF-A, CXCL8, MMP-9) and lymphangiogenic factors (VEGF-C and VEGF-F). Gastric mast cells express the programmed death ligands (PD-L1 and PD-L2) which are relevant as immune checkpoints in cancer. Several clinical undergoing trials targeting immune checkpoints could be an innovative therapeutic strategy in gastric cancer. Elucidation of the role of subsets of mast cells in different human gastric cancers will demand studies of increasing complexity beyond those assessing merely mast cell density and microlocalization.