The gut-enthesis axis and the pathogenesis of Spondyloarthritis.

Subclinical inflammation is associated with Spondylarthritis (SpA). SpA patients show features of dysbiosis, altered gut barrier function, and local expansion of innate and innate-like cells involved in type 3 immune response. The recirculation of intestinal primed immune cells into the bloodstream and, in some cases, in the joints and the inflamed bone marrow of SpA patients gave the basis of the gut-joint axis theory. In the light of the critical role of enthesis in the pathogenesis of SpA and the identification of mucosal-derived immune cells residing into the normal human enthesis, a gut-enthesis axis is also likely to exist. This work reviews the current knowledge on enthesis-associated innate immune cells' primary involvement in enthesitis development, questions their origin, and critically discusses the clues supporting the existence of a gut-enthesis axis contributing to SpA development.

Expression of HIF1α in intestinal epithelium restricts arthritis inflammation by inhibiting RIPK3-induced cell death machinery.

OBJECTIVES: To investigate the mechanism by which intestinal epithelial cell (IEC) death induces arthritis. METHODS: IEC death was assessed by staining for necroptosis and apoptosis markers and fluorescence in situ hybridisation at different time points during collagen-induced arthritis (CIA). During the development of CIA, messenger RNA (mRNA) sequencing was performed, followed by Gene Ontology enrichment analysis of differentially expressed genes. Mice deficient for hypoxia-inducible factor 1α (Hif1a) in IECs (Hif1a ∆IEC) were generated and induced for arthritis. mRNA sequencing, chromatin immunoprecipitated (ChIP) DNA sequencing and ChIP-qualitative PCR were performed on IECs from Hif1a ∆IEC mice and littermate controls. Effects of HIF1α stabilisation by inhibition of prolyl hydroxylase domain-containing enzymes and treatment with the inhibitor of receptor-interacting protein kinase-3 (RIPK3) were tested in intestinal organoids and in CIA. RESULTS: IEC underwent apoptotic and necroptotic cell death at the onset of arthritis, leading to impaired gut barrier function. HIF1α was identified as one of the most upregulated genes in IECs during the onset of arthritis. Deletion of Hif1a in IEC enhanced IEC necroptosis, triggered intestinal inflammation and exacerbated arthritis. HIF1α was found to be a key transcriptional repressor for the necroptosis-inducing factor RIPK3. Enhanced RIPK3 expression, indicating necroptosis, was also found in the intestinal epithelium of patients with new-onset rheumatoid arthritis. Therapeutic stabilisation of HIF1α as well as small-molecule-based RIPK3 inhibition rescued intestinal necroptosis in vitro and in vivo and suppressed the development of arthritis. CONCLUSION: Our results identify IEC necroptosis as a critical link between the gut and the development of arthritis.

CD8+ tissue-resident memory T cells are expanded in primary Sjögren's disease and can be therapeutically targeted by CD103 blockade.

OBJECTIVE: Tissue-resident memory cells (Trm) are a subset of T cells residing persistently and long-term within specific tissues that contribute to persistent inflammation and tissue damage. We characterised the phenotype and function of Trm and the role of CD103 in primary Sjogren's syndrome (pSS). METHODS: In both pSS and non-pSS sicca syndrome patients, we examined Trm frequency, cytokine production in salivary glands (SG) and peripheral blood (PB). We also analysed Trm-related gene expression in SG biopsies through bulk and single-cell RNA sequencing (scRNAseq). Additionally, we investigated Trm properties in an immunisation-induced animal model of pSS (experimental SS, ESS) mouse model and assessed the effects of Trm inhibition via intraglandular anti-CD103 monoclonal antibody administration. RESULTS: Transcriptomic pSS SG showed an upregulation of genes associated with tissue recruitment and long-term survival of Trm cells, confirmed by a higher frequency of CD8+CD103+CD69+ cells in pSS SG, compared with non-specific sialadenitis (nSS). In SG, CD8+ CD103+ Trm contributed to the secretion of granzyme-B and interferon-γ, CD8+ Trm cells were localised within inflammatory infiltrates, where PD1+CD8+ T cells were also increased compared with nSS and MALT lymphoma. scRNAseq of PB and pSS SG T cells confirmed expression of CD69, ITGAE, GZMB, GZMK and HLA-DRB1 among CD3+CD8+ SG T cells. In the SG of ESS, CD8+CD69+CD103+ Trm producing Granzyme B progressively expanded. However, intraglandular blockade of CD103 in ESS reduced Trm, reduced glandular damage and improved salivary flow. CONCLUSIONS: CD103+CD8+Trm cells are expanded in the SG of pSS and ESS, participate in tissue inflammation and can be therapeutically targeted.

Short-term effectiveness of guselkumab in psoriatic arthritis patients and suggestive features of axial involvement: results from a real-life multicentre cohort.

OBJECTIVE: To evaluate the short-term effectiveness of guselkumab in patients with psoriatic arthritis (PsA) and suggestive features of axial involvement in a prospective "real-life" multicentre cohort. METHODS: Between June 2022 and June 2023, PsA patients with axial involvement were evaluated if treated at least for 4 months with guselkumab. The effectiveness was evaluated by BASDAI, ASDAS, DAPSA, and achievement of BASDAI ≤ 4, also exploiting predictive factors. In a group of patients, MRI findings on sacroiliac joints were assessed before and after guselkumab administration. RESULTS: Sixty-seven patients with PsA and suggestive features of axial involvement (age 53.4 ± 11.2 years, male sex 26.9%) were treated with guselkumab. After 4 months, a significant reduction of BASDAI, ASDAS, and DAPSA was observed. A ΔBASDAI of -2.11 ± 0.43 was estimated assessing the mean difference values before and after guselkumab administration and 52.2% of patients reached a BASDAI ≤ 4. In 27 patients, MRI findings on sacroiliac joints were assessed before and after guselkumab administration. A reduction of 0.80 or larger of the sacroiliac joint lesion score was observed in the majority of patients (70.3%) based on MRI improvements, paralleling with the clinical response.No life-threatening side effects were recorded; 17.9% of patients reported minor adverse events mainly injection site reactions. CONCLUSIONS: The short-term effectiveness of guselkumab in patients with PsA and suggestive features of axial involvement was shown. Although further studies are needed, our multicentre "real-life" study may suggest the clinical usability of guselkumab in this context.

JAK/STAT inhibition modifies the ILC1 immune response in patients with rheumatoid arthritis.

OBJECTIVES: Recent evidence suggests that innate lymphoid cells (ILCs) might be involved in rheumatoid arthritis (RA) pathogenesis and individuals at risk of RA exhibited an increased frequency of ILC1. JAK3 participates in ILC1 and ILC3 differentiation. Tofacitinib and the Janus Kinase (JAK) 3 inhibitor, PF-06651600, impair the ability of human intraepithelial ILC1 (iILC1) to produce IFN-γ and the proliferation of ILC1 and ILC3. Our study aims to evaluate the ex vivo effects of tofacitinib in RA patients and to investigate if ILC1s and ILC3s are specific targets of tofacitinib in RA. METHODS: Twenty RA patients starting tofacitinib and 10 RA patients starting anti-TNFα were enrolled. Peripheral blood mononuclear cells (PBMCs) from RA patients, collected before and three months after therapy, were cultured to evaluate ILC1 and ILC3 frequencies and the respective production of IFN-γ and IL-17 by flow cytometry analysis. PBMCs of RA patients were in vitro cultured with tofacitinib to evaluate the dose effects on ILC frequencies. RESULTS: RA patients showed a significant expansion of ILC1 but not ILC3. Unlike anti-TNFα treated patients, in whom no reduction in ILCs was reported, after three months of tofacitinib therapy the overall ILC frequency was reduced, as well as the ILC1 ability to release IFN-γ. In vitro treatment of PBMCs with tofacitinib demonstrated a dose-dependent reduction in the frequency of ILCs compared to untreated cells. CONCLUSIONS: Our preliminary results demonstrate that tofacitinib modulates the innate immune response by reducing the frequency of ILC1 cells and their production of IFN-γ.

The assessment of the drug retention rate of secukinumab in patients with psoriatic arthritis in a real-life multicentre cohort.

OBJECTIVES: We aimed to evaluate the drug retention rate (DRR) of secukinumab, an anti-IL-17A monoclonal antibody, in patients with psoriatic arthritis (PsA) in a real-life cohort, and to assess the impact of comorbidities and patient clinical characteristics on the DRR of secukinumab. METHODS: A retrospective study of prospective followed-up patients was performed to evaluate the DRR of secukinumab on patients with PsA attending the recruiting centres between January 2016 and June 2022. RESULTS: In 207 patients with PsA, a 60-month DRR of secukinumab of 57.0% was estimated (mean time of administration of 21.5±17.1 months). Male gender, age ≥65 years, disease duration ≥5 years and ≥10 years did not influence the DRR of secukinumab. The presence of comorbidities, considering any concomitant disorder, did not affect the DRR of secukinumab. In patients with cardiometabolic multimorbidity, a trend toward a better DRR of secukinumab was recorded. In fact, patients with high blood pressure, dyslipidaemia, and type 2 diabetes showed a trend toward an improved DRR of secukinumab. Furthermore, the presence of obesity did not influence the DRR of secukinumab. Different dosages, previous bDMARDs, and concomitant therapy with csDMARDs did not influence the DRR of secukinumab. CONCLUSIONS: A cumulative 60-month DRR of secukinumab of 57.0% in patients with PsA was retrieved. The presence of cardiometabolic multimorbidity could be associated with an improved DRR of secukinumab, whereas obesity did not affect this feature in our cohort. Previous bDMARDs, concomitant csDMARDs, and different drug dosages could not influence the DRR of secukinumab over time.

Clinical correlates of a subset of anti-fibroblast antibodies in systemic sclerosis.

Anti-fibroblast antibodies (AFA) have been reported in systemic sclerosis (SSc) and are known to promote fibroblast activation. Aim of this study was to characterize the fine specificity of AFA and to analyze any correlations with clinical parameters associated to fibrosis. To this end, AFA were affinity-purified from a patient with diffuse cutaneous SSc (dcSSc) and interstitial lung disease (ILD). Panning of a phage display peptide library with purified AFA identified the motif . The peptide p121, bearing the AFA-specific motif, was used in ELISA to screen sera from 186 SSc patients and 81 healthy donors. Anti-p121 Ab serum levels were statistically higher in SSc than in healthy groups, and directly associated with dcSSc, reduced FVC (FVC < 70), and ILD. Given these clinical correlates, this study lays the groundwork for the identification of the antigen recognized by anti-p121 Ab, which might represent a novel therapeutic target for ILD.

Genetically encoded Runx3 and CD4+ intestinal epithelial lymphocyte deficiencies link SKG mouse and human predisposition to spondyloarthropathy.

Disturbances in immune regulation, intestinal dysbiosis and inflammation characterize ankylosing spondylitis (AS), which is associated with RUNX3 loss-of-function variants. ZAP70W163C mutant (SKG) mice have reduced ZAP70 signaling, spondyloarthritis and ileitis. In small intestine, Foxp3+ regulatory T cells (Treg) and CD4+CD8αα+TCRαß+ intraepithelial lymphocytes (CD4-IEL) control inflammation. TGF-ß and retinoic acid (RA)-producing dendritic cells and MHC-class II+ intestinal epithelial cells (IEC) are required for Treg and CD4-IEL differentiation from CD4+ conventional or Treg precursors, with upregulation of Runx3 and suppression of ThPOK. We show in SKG mouse ileum, that ZAP70W163C or ZAP70 inhibition prevented CD4-IEL but not Treg differentiation, dysregulating Runx3 and ThPOK. TGF-ß/RA-mediated CD4-IEL development, T-cell IFN-γ production, MHC class-II+ IEC, tissue-resident memory T-cell and Runx3-regulated genes were reduced. In AS intestine, CD4-IEL were decreased, while in AS blood CD4+CD8+ T cells were reduced and Treg increased. Thus, genetically-encoded TCR signaling dysfunction links intestinal T-cell immunodeficiency in mouse and human spondyloarthropathy.

Prostaglandin E2/EP4 axis is upregulated in Spondyloarthritis and contributes to radiographic progression.

Ankylosing spondylitis (AS) is an inflammatory disease leading to spine ankylosis; however, the mechanisms behind new bone formation are still not fully understood. Single Nucleotide Polymorphisms (SNPs) in PTGER4, encoding for the receptor EP4 of prostaglandin E2 (PGE2), are associated with AS. Since the PGE2-EP4 axis participates in inflammation and bone metabolism, this work aims at investigating the influence of the prostaglandin-E2 axis on radiographic progression in AS. In 185 AS (97 progressors), baseline serum PGE2 predicted progression, and PTGER4 SNP rs6896969 was more frequent in progressors. Increased EP4/PTGER4 expression was observed in AS circulating immune cells, synovial tissue, and bone marrow. CD14highEP4 + cells frequency correlated with disease activity, and when monocytes were cocultured with mesenchymal stem cells, the PGE2/EP4 axis induced bone formation. In conclusion, the Prostaglandin E2 axis is involved in bone remodelling and may contribute to the radiographic progression in AS due to genetic and environmental upregulation.

Butyrophilin 2a2 (Btn2a2) expression on thymic epithelial cells promotes central T cell tolerance and prevents autoimmune disease.

Butyrophilins are surface receptors belonging to the immunoglobulin superfamily. While several members of the butyrophilin family have been implicated in the development of unconventional T cells, butyrophilin 2a2 (Btn2a2) has been shown to inhibit conventional T cell activation. Here, we demonstrate that in steady state, the primary source of Btn2a2 are thymic epithelial cells (TEC). Absence of Btn2a2 alters thymic T cell maturation and bypasses central tolerance mechanisms. Furthermore, Btn2a2-/- mice develop spontaneous autoimmunity resembling human primary Sjögren's Syndrome (pSS), including formation of tertiary lymphoid structures (TLS) in target organs. Ligation of Btn2a2 on developing thymocytes is associated with reduced TCR signaling and CD5 levels, while absence of Btn2a2 results in increased TCR signaling and CD5 levels. These results define a novel role for Btn2a2 in promoting central tolerance by modulating TCR signaling strength and indicate a potential mechanism of pSS development.

Peripheral arthritis in psoriatic arthritis: from immunopathogenesis to therapy with Janus kinase inhibitors.

Psoriatic arthritis (PsA) is a chronic systemic inflammatory disease characterised by high phenotypic heterogeneity. Peripheral polyarticular, pauciarticular, axial, enthesitic, and dactylitic forms have been classically described, although it is not clear whether they all have the same pathophysiological mechanisms. Use of cytokine-targeted therapies in the last 20 years has significantly impacted the quality of life of patients with PsA even though a significant proportion of patients, regardless of the mechanism of action considered, remain non-responders, suggesting the need for better understanding of the pathophysiological basis of the disease to appropriately stratify patients and identify new therapeutic targets. The pre-clinical demonstration of the pathophysiological relevance of the JAK/STAT pathway in the pathogenesis of PsA and the emerging efficacy data from randomised controlled trials of JAK inhibitors in PsA patients have set the stage for a new pharmacological era in patients with PsA. In this review, we discuss the rationale for using approved JAK inhibitors for treatment of peripheral PsA and their positioning in the context of EULAR/GRAPPA guidelines.

Seronegative rheumatoid arthritis: one year in review 2023.

In the past 20 years, earlier diagnosis and more intensive management have considerably improved the prognosis of rheumatoid arthritis (RA), with milder disease course achieved in particular in seropositive patients. In contrast, seronegative RA has remained largely neglected, and continues to be surrounded by uncertainties regarding its correct diagnosis, clinical phenotype, optimal treatment strategies and relevant outcomes.The purpose of this review is to summarise new insights about the pathogenic, clinical and prognostic peculiarities of seronegative RA that emerged during 2022, and that make this disease subset at least partially different from its seropositive counterpart.

Interleukin 9 neutralisation reduces collagen-induced arthritis severity in mouse models.

OBJECTIVES: Interleukin 9 (IL-9) is a mediator of tissue damage in several inflammatory diseases. In this study we aimed to evaluate the effects of in vivo IL-9 neutralisation in mice developing collagen induced arthritis (CIA). METHODS: DBA/1 were immunised with collagen in Freund's complete adjuvant (CFA) to induce arthritis. Anti-IL-9 mAb was injected in mice after the onset of arthritis (Group A) or on the same day as sensitisation and again on the day of the challenge (Group B). Histological analysis was performed in joints of mice and spleen cells were also analysed by flow cytometry. A geneset analysis was carried out on whole tarsal joint tissue transcriptomes. RESULTS: IL-9 was over-expressed in swollen joints of mice developing arthritis. Treatment with anti-IL-9 mAb after arthritis onset efficiently down-modulated the severity of joint inflammation. Similarly, anti-IL-9 mAb administered on the same day as sensitisation and on the day of challenge also delayed the onset of arthritis. Anti-IL-9 mAb injection after the onset of arthritis was associated with a decrease of CD4+ TNF-α+ cells and an increase of CD4+ FoxP3+ IL-10+ cells. Geneset analysis in CIA showed an up-regulation of GATA3 with no significant direct interactions between IL-9 and GATA3, which instead was mediated by IL-5 through STAT6. CONCLUSIONS: Our results suggest that IL-9 is involved in the immunopathogenesis of CIA. Further implications for the clinical translation of our findings are discussed.

Cardiovascular comorbidities in psoriatic arthritis: epidemiology and risk factors in two different European populations.

OBJECTIVES: Psoriatic arthritis (PsA) is a chronic inflammatory disease, frequently associated with cardiovascular (CV) comorbidities. Our aim was to compare the prevalence of CV comorbidities between two groups of PsA patients from different European countries: Belgium and Italy. METHODS: This is a cross-sectional analysis of two longitudinal cohorts in which 803 PsA patients were enrolled (463 from Belgium and 340 from Italy). All enrolled patients were ≥18 years old and fulfilled the ClASsification criteria for Psoriatic Arthritis (CASPAR criteria). For each patient, demographics, clinical assessments, smoking habits, the presence of arterial hypertension (AH), obesity (BMI ≥30), type 2 diabetes (T2D), CV diseases (acute myocardial infarction, stroke or transient ischaemic attack), dyslipidaemia (Italy only) and hypercholesterolaemia (Belgium only) were collected. RESULTS: The most prevalent comorbidities among Italian patients with PsA were: AH (45.1%), dyslipidaemia (38.6%) and obesity (30.8%), and among Belgian patients were: hypercholesterolaemia (30.9%), obesity (27%) and AH (26.4%). Moreover, the prevalence of T2D and CV diseases was respectively 14.2% and 7.1% among Italian patients and 7.6% and 3.5% among Belgian patients. When comparing the two groups, AH, T2D and CV diseases were significantly more prevalent in Italian PsA patients. After controlling for different confounders, Italian patients, regardless of age, sex, smoking habits, PsA duration, other CV comorbidities, therapy, disease activity and function, had a higher risk to be hypertensive (OR 2.00, p=0.007). Instead of the country in which patients lived was not a predictor for the risk of T2D and CV diseases. Obesity prevalence was not different between the two groups. The lipid profile was unfavourable in both populations (even if not comparable between the two groups, due to the different way of collection), as is often the case in PsA. CONCLUSIONS: The prevalence of AH, T2D and CV diseases were higher in Italian patients rather than Belgians. Moreover, among patients with PsA, the risk of AH was higher in the Italian cohort compared to the Belgian cohort. These results suggest that further research is needed to evaluate potential extrinsic factors (geography and sociocultural aspects) that may contribute to CV risk.

Adherence to therapy in people with rheumatic and musculoskeletal diseases in Italy and the role of the digital health: results of an expert Delphi consensus survey.

OBJECTIVES: To present the results of a Delphi consensus survey among Italian rheumatologists on adherence to therapy in people with rheumatic and musculoskeletal diseases (RMDs) in Italy and the role of digital health. METHODS: A taskforce of 12 rheumatologists comprehensively discussed the applicability of the 2020 EULAR Points to Consider (PtCs) for Italian rheumatology practice and formulated 44 new country-specific statements. Through an on-line survey, the panellists voted on their level of agreement with the statements using a 10-point Likert scale (0: no agreement; 10: total agreement). A combination of two distinct criteria, a mean agreement level ≥8 and a percentage of at least 75% of responses with a value ≥8, was deemed acceptable. RESULTS: The consensus threshold was reached for 43 of the 44 country-specific statements. The following were acknowledged among the barriers to applicability of the recommendations: visit time too short; lack of resources; lack of a clear operational flow-chart; lack of communication skills and poor knowledge of techniques to improve patient adherence by healthcare professionals (HCPs). CONCLUSIONS: This consensus initiative helps contribute to more widespread implementation of EULAR PtCs in Italian rheumatology practice. Optimisation of visit time, greater availability of resources, specific training, use of standardised and validated protocols, and active involvement of patients represent the main goals. Digital health can provide valuable support for the application of PtCs and, more generally, in improving adherence. A collaborative effort between HCPs, patients and their associations, scientific societies, and policymakers is strongly advocated to overcome some of the barriers.

Persistence, effectiveness and safety of ustekinumab compared to TNF inhibitors in psoriatic arthritis within the Italian PsABio cohort.

OBJECTIVES: To compare real-world persistence, effectiveness and tolerability of ustekinumab versus TNF inhibitors (TNFi) in psoriatic arthritis (PsA). METHODS: One-year data from Italian subjects enrolled in the PsABio study (PsA patients receiving 1st- to 3rd-line treatment with ustekinumab or TNFi) were evaluated. Treatment persistence was analysed using Kaplan-Meier curves; hazard ratios (HR) of stopping treatment, and the corresponding 95% confidence intervals (CI), were computed through Cox regression models. Proportions of patients reaching clinical effectiveness endpoints were analysed using logistic regression, including propensity score (PS) adjustment for imbalanced baseline covariates, and non-response imputation if treatment was stopped/switched. RESULTS: Among 222 participants with follow-up data (effectiveness set), 101 received ustekinumab and 121 TNFi. In the ustekinumab group, 74.3% continued treatment up to 12±3 months compared to 63.6% in the TNFi group. Ustekinumab showed better persistence than TNFi, overall and in specific subgroups (females, monotherapy without methotrexate, BMI <25 or >30 kg/m2, patients receiving ustekinumab as 2nd-line treatment instead of a second TNFi). Overall, the PS-adjusted HR of treatment discontinuation was 0.46 (95% CI: 0.26-0.82) for ustekinumab vs. TNFi. cDAPSA LDA/remission was achieved in 43.5% of ustekinumab and 43.6% of TNFi-treated patients, while MDA was achieved in 24.2% and 28.0% of patients, respectively. After PS adjustment, odds ratios of clinical effectiveness did not differ significantly. Both treatments showed an acceptable safety profile. CONCLUSIONS: This prospective, real-life study found a better persistence of ustekinumab than TNFi in PsA patients. At 1 year, both treatments showed similar effectiveness.

The negative impact of pain catastrophising on disease activity: analyses of data derived from patient-reported outcomes in psoriatic arthritis and axial spondyloarthritis.

OBJECTIVES: Psychosocial factors are recognised as important determinants of pain experience in patients with inflammatory arthritides. Among them, pain catastrophising, a maladaptive cognitive style, observed in patients with anxiety and depressive disorders, garnered specific attention. Here, we evaluated pain catastrophising (PC) and its related domains (Rumination, Magnification, and Helplessness), in psoriatic arthritis (PsA) and axial spondyloarhtiritis (axSpA) participants, to assess its impact on disease activity. Furthermore, we analysed possible correlations of PC-Scale (PCS) with those psychometric domains which have been already related to catastrophisation in patients with chronic pain. Lastly, we aimed to define the relationship between PCS and the different variables included in the composite indices of disease activity. METHODS: A multi-centre, cross-sectional, observational study has been conducted on 135 PsA (age 56 (47-64) years, males/females 40.74/59.26%; Disease Activity in Psoriasic Arthritis (DAPSA) 13.34 (5.21-22.22)) and 71 axSpA (age 49 (37-58) years, males/females 56.34/43.66%; Bath Ankylosing Spondylitis Arthritis Activity (BASDAI) 4.17 (2.1-6.3)) participants. Multivariable regressions and correlations were performed to evaluate the relationship between pain catastrophising and both disease activity and patient-reported outcomes. RESULTS: The adjusted linear regression model showed a positive association between PCS and DAPSA as well as between PCS and BASDAI; PCS negative impacts on the subjective domains of disease activity scores. CONCLUSIONS: This study suggests the role of PC, independently of inflammation, in disease perception and achievement of remission or low disease activity in chronic arthritides.

Will fecal microbiota transplantation eventually be an effective therapeutic strategy for systemic lupus erythematosus?

Gut microbiota dysbiosis serves as a potential trigger that may contribute to metabolic and immune dysregulation that underlies the development of autoimmune diseases. Fecal microbiota transplantation (FMT) is restoration of disturbed microbiota by transplanting foreign gut microbiota from healthy individuals into the gastrointestinal tract of diseased individuals. In this issue of the Journal of Autoimmunity, Huang et al. conducted a 12-week, single-arm pilot clinical trial of oral FMT capsules in patients with active SLE. No serious adverse events (AEs) or deaths were observed and the rate of the primary endpoint (SLE Responder Index-4) was 42.12%. Alternations in bacteria, metabolites and immune parameters were linked to FMT treatment and clinical response in SLE patients. This is the first FMT trial in SLE patients and provides supportive evidence that FMT appears to be a safe, feasible and potentially effective treatment modality in SLE. We await future investigations conducting larger, randomized FMT clinical trials with a longer follow-up to confirm the long-term safety, effectiveness, and potential benefits of FMT-based intervention in SLE and to further demonstrate the underlying microbiological mechanisms.

Epithelial HIF2α expression induces intestinal barrier dysfunction and exacerbation of arthritis.

OBJECTIVE: To investigate how the mucosal barrier in the intestine influences the development of arthritis, considering that metabolic changes in the intestinal epithelium influence its barrier function. METHODS: Intestinal hypoxia inducible factor (HIF)-2α expression was assessed before, at onset and during experimental arthritis and human rheumatoid arthritis (RA). Intestinal epithelial cell-specific HIF2α conditional knock-out mice were generated (HIF2α∆IEC) and subjected to collagen-induced arthritis. Clinical and histological courses of arthritis were recorded; T-cell and B-cell subsets were analysed in the gut and secondary lymphatic organs; and intestinal epithelial cells were subjected to molecular mRNA sequencing in HIF2α∆IEC and littermate control mice. The gut intestinal HIF2α target genes were delineated by chromatin immunoprecipitation and luciferase experiments. Furthermore, pharmacological HIF2α inhibitor PT2977 was used for inhibition of arthritis. RESULTS: Intestinal HIF2α expression peaked at onset of experimental arthritis and RA. Conditionally, deletion of HIF2α in gut epithelial cells inhibited arthritis and was associated with improved intestinal barrier function and less intestinal and lymphatic Th1 and Th17 activation. Mechanistically, HIF2α induced the transcription of the pore-forming claudin (CLDN)-15, which inhibits intestinal barrier integrity. Furthermore, treatment with HIF2α inhibitor decreased claudin-15 expression in epithelial cells and inhibited arthritis. CONCLUSION: These findings show that the HIF2α-CLDN15 axis is critical for the breakdown of intestinal barrier function at onset of arthritis, highlighting the functional link between intestinal homeostasis and arthritis.

Real-life efficacy of guselkumab in patients with early psoriatic arthritis.

OBJECTIVES: To assess the efficacy of the novel anti-IL-23 monoclonal antibody guselkumab in a real-life observational cohort of patients with early PsA. METHODS: We conducted an observational study on patients with early PsA followed by the joint dermatology-rheumatology clinics of two Italian centres starting therapy with guselkumab for severe skin involvement. Each patient was evaluated at baseline and every 24 weeks for one year, recording Disease Activity Index for PsA (DAPSA), PASI, VAS Pain, VAS Prutitus, Patient's Global Assessment (PtGA) and assessing DAPSA response. RESULTS: Twenty-four patients were recruited (16 women). The mean duration of skin disease was 12.5 years (CI 8; 17), but all patients had a shorter articular disease duration, 21.29 months (CI 15.9; 26.68). At baseline, all patients displayed a moderate cutaneous disease with a mean PASI of 15.2 (CI 11.7-18.6) and high disease activity, characterized by mean DAPSA of 26.84 (CI 22.49-31.19). An inflammatory low back pain was reported by five patients (20%) with a mean BASDAI 5.1 (CI 4,38-5,85) at baseline. The majority of guselkumab-treated patients (n = 18; 75%) reached DAPSA remission or DAPSA low disease activity after six months. Seventeen out of 24 patients completed 12 months of treatment, 11 of them (65%) in low disease activity, six (35%) in remission. All patients with axial disease reported improvement of inflammatory low back pain at week 24 with a mean BASDAI 2.98 (CI 2,18- 3,77). No significant side effects were reported. CONCLUSIONS: Real-life data on a cohort of early PsA patients confirm the efficacy and safety of guselkumab on peripheral and axial manifestations.