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Objective: The objective for this study was to evaluate the effects of short chain fatty acids (SCFAs) on arthritic bone remodeling., Methods: We treated a recently described preclinical murine model of psoriatic arthritis (PsA), R26STAT3C stopfl/fl CD4Cre mice, with SCFA-supplemented water. We also performed in vitro osteoclast differentiation assays in the presence of serum-level SCFAs to evaluate the direct impact of these microbial metabolites on maturation and function of osteoclasts. We further characterized the molecular mechanism of SCFAs by transcriptional analysis., Results: The osteoporosis condition in R26STAT3C stopfl/fl CD4Cre animals is attributed primarily to robust osteoclast differentiation driven by an expansion of osteoclast progenitor cells (OCPs), accompanied by impaired osteoblast development. We show that SCFA supplementation can rescue the osteoporosis phenotype in this model of PsA. Our in vitro experiments revealed an inhibitory effect of the SCFAs on osteoclast differentiation, even at very low serum concentrations. This suppression of osteoclast differentiation enabled SCFAs to impede osteoporosis development in R26STAT3C stopfl/fl CD4Cre mice. Further interrogation revealed that bone marrow-derived OCPs from diseased mice expressed a higher level of SCFA receptors than those of control mice and that the progenitor cells in the bone marrow of SCFA-treated mice presented a modified transcriptomic landscape, suggesting a direct impact of SCFAs on bone marrow progenitors in the context of osteoporosis., Conclusion: We demonstrated how gut microbiota-derived SCFAs can regulate distal pathology (ie, osteoporosis) and identified a potential therapeutic option for restoring bone density in rheumatic disease, further highlighting the critical role of the gut-bone axis in these disorders., (© 2023 American College of Rheumatology.)

Objective: To evaluate seroreactivity and disease flares after COVID-19 vaccination in a multiethnic/multiracial cohort of patients with systemic lupus erythematosus (SLE)., Methods: Ninety SLE patients and 20 healthy controls receiving a complete COVID-19 vaccine regimen were included. IgG seroreactivity to the SARS-CoV-2 spike receptor-binding domain (RBD) and SARS-CoV-2 microneutralization were used to evaluate B cell responses; interferon-γ (IFNγ) production was measured by enzyme-linked immunospot (ELISpot) assay in order to assess T cell responses. Disease activity was measured by the hybrid SLE Disease Activity Index (SLEDAI), and flares were identified according to the Safety of Estrogens in Lupus Erythematosus National Assessment-SLEDAI flare index., Results: Overall, fully vaccinated SLE patients produced significantly lower IgG antibodies against SARS-CoV-2 spike RBD compared to fully vaccinated controls. Twenty-six SLE patients (28.8%) generated an IgG response below that of the lowest control (<100 units/ml). In logistic regression analyses, the use of any immunosuppressant or prednisone and a normal anti-double-stranded DNA antibody level prior to vaccination were associated with decreased vaccine responses. IgG seroreactivity to the SARS-CoV-2 spike RBD strongly correlated with the SARS-CoV-2 microneutralization titers and correlated with antigen-specific IFNγ production determined by ELISpot. In a subset of patients with poor antibody responses, IFNγ production was similarly diminished. Pre- and postvaccination SLEDAI scores were similar in both groups. Postvaccination flares occurred in 11.4% of patients; 1.3% of these were severe., Conclusion: In a multiethnic/multiracial study of SLE patients, 29% had a low response to the COVID-19 vaccine which was associated with receiving immunosuppressive therapy. Reassuringly, severe disease flares were rare. While minimal protective levels remain unknown, these data suggest that protocol development is needed to assess the efficacy of booster vaccination., (© 2021, American College of Rheumatology.)

Objective: Although oral methotrexate (MTX) remains the anchor drug for rheumatoid arthritis (RA), up to 50% of patients do not achieve a clinically adequate outcome. In addition, there is a lack of prognostic tools for treatment response prior to drug initiation. This study was undertaken to investigate whether interindividual differences in the human gut microbiome can aid in the prediction of MTX efficacy in new-onset RA., Methods: We performed 16S ribosomal RNA gene and shotgun metagenomic sequencing on the baseline gut microbiomes of drug-naive patients with new-onset RA (n = 26). Results were validated in an additional independent cohort (n = 21). To gain insight into potential microbial mechanisms, we conducted ex vivo experiments coupled with metabolomics analysis to evaluate the association between microbiome-driven MTX depletion and clinical response., Results: Our analysis revealed significant associations of the abundance of gut bacterial taxa and their genes with future clinical response (q < 0.05), including orthologs related to purine and MTX metabolism. Machine learning techniques were applied to the metagenomic data, resulting in a microbiome-based model that predicted lack of response to MTX in an independent group of patients. Finally, MTX levels remaining after ex vivo incubation with distal gut samples from pretreatment RA patients significantly correlated with the magnitude of future clinical response, suggesting a possible direct effect of the gut microbiome on MTX metabolism and treatment outcomes., Conclusion: Taken together, these findings are the first step toward predicting lack of response to oral MTX in patients with new-onset RA and support the value of the gut microbiome as a possible prognostic tool and as a potential target in RA therapeutics., (© 2020, American College of Rheumatology.)

Objective: To characterize the hospitalization and death rates among patients with inflammatory arthritis (IA) affected by coronavirus disease 2019 (COVID-19) and to analyze the associations of comorbidities and immunomodulatory medications with infection outcomes., Methods: Data on clinical and demographic features, maintenance treatment, disease course, and outcomes in individuals with IA (rheumatoid arthritis and spondyloarthritis) with symptomatic COVID-19 infection were prospectively assessed via web-based questionnaire followed by individual phone calls and electronic medical record review. Baseline characteristics and medication use were summarized for hospitalized and ambulatory patients, and outcomes with the different medication classes were compared using multivariable logistic regression., Results: A total of 103 patients with IA were included in the study (80 with confirmed COVID-19 and 23 with high suspicion of COVID-19). Hospitalization was required in 26% of the participants, and 4% died. Patients who were hospitalized were significantly more likely to be older (P < 0.001) and have comorbid hypertension (P = 0.001) and chronic obstructive pulmonary disease (P = 0.02). IA patients taking oral glucocorticoids had an increased likelihood of being admitted for COVID-19 (P < 0.001), while those receiving maintenance anticytokine biologic therapies did not., Conclusion: Among patients with underlying IA, COVID-19 outcomes were worse in those receiving glucocorticoids but not in patients receiving maintenance anticytokine therapy. Further work is needed to understand whether immunomodulatory therapies affect COVID-19 incidence., (© 2020, American College of Rheumatology.)

Objective: To characterize patients with systemic lupus erythematosus (SLE) affected by coronavirus disease 2019 (COVID-19) and to analyze associations of comorbidities and medications on infection outcomes., Methods: Patients with SLE and reverse transcriptase-polymerase chain reaction-confirmed COVID-19 were identified through an established New York University lupus cohort, query of 2 hospital systems, and referrals from rheumatologists. Data were prospectively collected via a web-based questionnaire and review of medical records. Data on baseline characteristics were obtained for all patients with COVID-19 to analyze risk factors for hospitalization. Data were also collected on asymptomatic patients and those with COVID-19-like symptoms who tested negative or were not tested. Statistical analyses were limited to confirmed COVID-19-positive patients., Results: A total of 226 SLE patients were included: 41 with confirmed COVID-19, 19 who tested negative for COVID-19, 42 with COVID-19-like symptoms who did not get tested, and 124 who remained asymptomatic without testing. Of the SLE patients with confirmed COVID-19, hospitalization was required in 24 (59%) and intensive care unit-level of care in 4, and 4 died. Hospitalized patients tended to be older, nonwhite, Hispanic, have higher body mas index (BMI), history of nephritis, and at least 1 comorbidity. An exploratory (due to limited sample size) logistic regression analysis identified race, presence of at least 1 comorbidity, and BMI as independent predictors of hospitalization., Conclusion: In general, the variables predictive of hospitalization in our SLE patients were similar to those identified in the general population. Further studies are needed to understand additional risk factors for poor COVID-19 outcomes in patients with SLE., (© 2020, American College of Rheumatology.)

Objective: To characterize the ecological effects of biologic therapies on the gut bacterial and fungal microbiome in psoriatic arthritis (PsA)/spondyloarthritis (SpA) patients., Methods: Fecal samples from PsA/SpA patients pre- and posttreatment with tumor necrosis factor inhibitors (TNFi; n = 15) or an anti-interleukin-17A monoclonal antibody inhibitor (IL-17i; n = 14) underwent sequencing (16S ribosomal RNA, internal transcribed spacer and shotgun metagenomics) and computational microbiome analysis. Fecal levels of fatty acid metabolites and cytokines/proteins implicated in PsA/SpA pathogenesis or intestinal inflammation were correlated with sequence data. Additionally, ileal biopsies obtained from SpA patients who developed clinically overt Crohn's disease (CD) after treatment with IL-17i (n = 5) were analyzed for expression of IL-23/Th17-related cytokines, IL-25/IL-17E-producing cells, and type 2 innate lymphoid cells (ILC2s)., Results: There were significant shifts in abundance of specific taxa after treatment with IL-17i compared to TNFi, particularly Clostridiales (P = 0.016) and Candida albicans (P = 0.041). These subclinical alterations correlated with changes in bacterial community co-occurrence, metabolic pathways, IL-23/Th17-related cytokines, and various fatty acids. Ileal biopsies showed that clinically overt CD was associated with expansion of IL-25/IL-17E-producing tuft cells and ILC2s (P < 0.05), compared to pre-IL-17i treatment levels., Conclusion: In a subgroup of SpA patients, the initiation of IL-17A blockade correlated with features of subclinical gut inflammation and intestinal dysbiosis of certain bacterial and fungal taxa, most notably C albicans. Further, IL-17i-related CD was associated with overexpression of IL-25/IL-17E-producing tuft cells and ILC2s. These results may help to explain the potential link between inhibition of a specific IL-17 pathway and the (sub)clinical gut inflammation observed in SpA., (© 2019, American College of Rheumatology.)

Objective: To develop an evidence-based guideline for the pharmacologic and nonpharmacologic treatment of psoriatic arthritis (PsA), as a collaboration between the American College of Rheumatology (ACR) and the National Psoriasis Foundation (NPF)., Methods: We identified critical outcomes in PsA and clinically relevant PICO (population/intervention/comparator/outcomes) questions. A Literature Review Team performed a systematic literature review to summarize evidence supporting the benefits and harms of available pharmacologic and nonpharmacologic therapies for PsA. GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology was used to rate the quality of the evidence. A voting panel, including rheumatologists, dermatologists, other health professionals, and patients, achieved consensus on the direction and the strength of the recommendations., Results: The guideline covers the management of active PsA in patients who are treatment-naive and those who continue to have active PsA despite treatment, and addresses the use of oral small molecules, tumor necrosis factor inhibitors, interleukin-12/23 inhibitors (IL-12/23i), IL-17 inhibitors, CTLA4-Ig (abatacept), and a JAK inhibitor (tofacitinib). We also developed recommendations for psoriatic spondylitis, predominant enthesitis, and treatment in the presence of concomitant inflammatory bowel disease, diabetes, or serious infections. We formulated recommendations for a treat-to-target strategy, vaccinations, and nonpharmacologic therapies. Six percent of the recommendations were strong and 94% conditional, indicating the importance of active discussion between the health care provider and the patient to choose the optimal treatment., Conclusion: The 2018 ACR/NPF PsA guideline serves as a tool for health care providers and patients in the selection of appropriate therapy in common clinical scenarios. Best treatment decisions consider each individual patient situation. The guideline is not meant to be proscriptive and should not be used to limit treatment options for patients with PsA., (© 2018, American College of Rheumatology.)

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., (© 2018 The Authors. Arthritis & Rheumatology published by Wiley Periodicals, Inc. on behalf of American College of Rheumatology.)

Objective: To introduce a novel preclinical animal model of psoriatic arthritis (PsA) in R26Stat3C stopfl/fl CD4Cre mice, and to investigate the role of Th17 cytokines in the disease pathogenesis., Methods: We characterized a novel murine model of Th17-driven cutaneous and synovio-entheseal disease directed by T cell-specific expression of a hyperactive Stat3 allele. By crossing R26Stat3C stopfl/fl CD4Cre mice onto an interleukin-22 (IL-22)-knockout background or treating the mice with a neutralizing antibody against IL-17, we interrogated how these Th17 cytokines could contribute to the pathogenesis of PsA., Results: R26Stat3C stopfl/fl CD4Cre mice developed acanthosis, hyperkeratosis, and parakeratosis of the skin, as well as enthesitis/tendinitis and periarticular bone erosion in different joints, accompanied by osteopenia. T cell-specific expression of a hyperactive Stat3C allele was found to drive the augmented Th17 response in these animals. Careful characterization of the mouse bone marrow revealed an increase in osteoclast progenitor (OCP) and RANKL-producing cells, which contributed to the osteopenia phenotype observed in the mutant animals. Abrogation of the Th17 cytokines IL-17 or IL-22 improved both the skin and bone phenotype in R26Stat3C stopfl/fl CD4Cre mice, revealing a central role of Th17 cells in the regulation of OCP and RANKL expression on stromal cells., Conclusion: Perturbation of the IL-23/Th17 axis instigates Th17-mediated inflammation in R26Stat3C stopfl/fl CD4Cre mice, leading to cutaneous and synovio-entheseal inflammation and bone pathologic features highly reminiscent of human PsA. Both IL-17A and IL-22 produced by Th17 cells appear to play critical roles in promoting the cutaneous and musculoskeletal inflammation that characterizes PsA., (© 2018, American College of Rheumatology.)

Objective: Reactive arthritis (ReA) is an inflammatory disorder occurring several weeks after gastrointestinal or genitourinary tract infections. HLA-B27 positivity is considered a risk factor, although it is not necessarily predictive of disease incidence. Among nongenetic factors, the intestinal microbiome may play a role in disease susceptibility. The objective of this study was to characterize the gut microbiota and host gene interactions in ReA and postinfectious spondyloarthritis., Methods: Adult subjects with peripheral spondyloarthritis and control subjects with preceding infections who did not develop arthritis were prospectively recruited from a geographic region with a high prevalence of ReA. Clinical variables, HLA status, and 16S ribosomal RNA gene sequencing of intestinal microbiota were analyzed., Results: Subjects with ReA showed no significant differences from controls in gut bacterial richness or diversity. However, there was a significantly higher abundance of Erwinia and Pseudomonas and an increased prevalence of typical enteropathogens associated with ReA. Subjects with ultrasound evidence of enthesitis were enriched in Campylobacter, while subjects with uveitis and radiographic sacroiliitis were enriched in Erwinia and unclassified Ruminococcaceae, respectively; both were enriched in Dialister. Host genetics, particularly HLA-A24, were associated with differences in gut microbiota diversity irrespective of disease status. We identified several co-occurring taxa that were also predictive of HLA-A24 status., Conclusion: This is the first culture-independent study characterizing the gut microbial community in postinfectious arthritis. Although bacterial factors correlated with disease presence and clinical features of ReA, host genetics also appeared to be a major independent driver of intestinal community composition. Understanding of these gut microbiota-host genetic relationships may further clarify the pathogenesis of postinfectious spondyloarthritides., (© 2017, American College of Rheumatology.)

Objective: To characterize the diversity and taxonomic relative abundance of the gut microbiota in patients with never-treated, recent-onset psoriatic arthritis (PsA)., Methods: High-throughput 16S ribosomal RNA pyrosequencing was utilized to compare the community composition of gut microbiota in patients with PsA (n = 16), patients with psoriasis of the skin (n = 15), and healthy, matched control subjects (n = 17). Samples were further assessed for the presence and levels of fecal and serum secretory IgA (sIgA), proinflammatory proteins, and fatty acids., Results: The gut microbiota observed in patients with PsA and patients with skin psoriasis was less diverse when compared to that in healthy controls. This could be attributed to the reduced presence of several taxa. Samples from both patient groups showed a relative decrease in abundance of Coprococcus species, while samples from PsA patients were also characterized by a significant reduction in Akkermansia, Ruminococcus, and Pseudobutyrivibrio. Supernatants of fecal samples from PsA patients revealed an increase in sIgA levels and decrease in RANKL levels. Analysis of fatty acids revealed low fecal quantities of hexanoate and heptanoate in both patients with PsA and patients with psoriasis., Conclusion: Patients with PsA and patients with skin psoriasis had a lower relative abundance of multiple intestinal bacteria. Although some genera were concomitantly decreased in both conditions, PsA samples had a lower abundance of reportedly beneficial taxa. This gut microbiota profile in PsA was similar to that previously described in patients with inflammatory bowel disease and was associated with changes in specific inflammatory proteins unique to this group, and distinct from that in patients with skin psoriasis and healthy controls. Thus, the role of the gut microbiome in the continuum of psoriasis-PsA pathogenesis and the associated immune response merits further study., (Copyright © 2015 by the American College of Rheumatology.)