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Background: Malondialdehyde–acetaldehyde (MAA) adducts lead to generation of anti‐MAA autoantibodies and have been independently identified in inflamed periodontal and rheumatoid arthritis (RA) tissues. This study evaluates serum samples from RA cases and osteoarthritis (OA) controls to quantify associations between periodontal clinical measures, alveolar bone loss (ABL), and anti‐Porphyromonas gingivalis, anti‐Prevotella intermedia, and anti‐Fusobacterium nucleatum antibody concentrations with anti‐MAA antibody concentrations. Methods: Participants (n = 284 RA cases, n = 330 OA controls) underwent periodontal clinical assessments and ABL measurements. Serum immunoglobulin (Ig) A, IgG, and IgM anti‐MAA and serum IgG antibacterial antibody concentrations were quantified by enzyme‐linked immunosorbent assay (ELISA). Analyses utilized simple linear regression and multivariable adjusted models. Results: No significant associations of periodontal clinical measures with serum anti‐MAA were found. Moderate (p = 0.038 and p = 0.036, respectively) and high ABL (p = 0.012 and p = 0.014, respectively) in RA cases (but not in OA) were positively associated with IgG and IgM anti‐MAA. Anti‐P. gingivalis and anti‐P. intermedia antibody concentrations were positively associated with IgA (p = 0.001 for both), IgG (p = 0.007 and p = 0.034, respectively), and IgM anti‐MAA antibody concentrations (p < 0.001 and p = 0.020, respectively), while anti‐F. nucleatum was positively associated with IgG anti‐MAA (p = 0.042), findings that were similar across groups. Conclusions: A positive association was demonstrated between ABL and serum IgG and IgM anti‐MAA antibody concentrations that was unique to RA and not observed in OA. Serum anti‐P. gingivalis, anti‐P. intermedia, and anti‐F. nucleatum antibody concentrations displayed significant associations with anti‐MAA antibody in both groups. These findings suggest MAA may play a role in the interrelationship between the periodontium and RA. [ABSTRACT FROM AUTHOR]

Background: Environmental lipopolysaccharide (LPS) and microbial component-enriched organic dusts cause significant lung disease. These environmental exposures induce the recruitment and activation of distinct lung monocyte/macrophage subpopulations involved in disease pathogenesis. Aconitate decarboxylase 1 (Acodl) was one of the most upregulated genes following LPS (vs. saline) exposure of murine whole lungs with transcriptomic profiling of sorted lung monocyte/macrophage subpopulations also highlighting its significance. Given monocyte/macrophage activation can be tightly linked to metabolism, the objective of these studies was to determine the role of the immunometabolic regulator ACOD1 in environmental exposure-induced lung inflammation. Methods: Wild-type (WT) mice were intratracheally (i.t.) instilled with 10 mg of LPS or saline. Whole lungs were profiled using bulk RNA sequencing or sorted to isolate monocyte/macrophage subpopulations. Sorted subpopulations were then characterized transcriptomically using a NanoString innate immunity multiplex array 48 h post-exposure. Next, WT and Acod1-/- mice were instilled with LPS, 25% organic dust extract (ODE), or saline, whereupon serum, bronchoalveolar lavage fluid (BALF), and lung tissues were collected. BALF metabolites of the tricarboxylic acid (TCA) cycle were quantified by mass spectrometry. Cytokines/chemokines and tissue remodeling mediators were quantitated by ELISA. Lung immune cells were characterized by flow cytometry. Invasive lung function testing was performed 3 h post-LPS with WT and Acodl-/- mice. Results: Acod1-/- mice treated with LPS demonstrated decreased BALF levels of itaconate, TCA cycle reprogramming, decreased BALF neutrophils, increased lung CD4+ T cells, decreased BALF and lung levels of TNF-α, and decreased BALF CXCL1 compared to WT animals. In comparison, Acod1-/- mice treated with ODE demonstrated decreased serum pentraxin-2, BALF levels of itaconate, lung total cell, neutrophil, monocyte, and B-cell infiltrates with decreased BALF levels of TNF-α and IL-6 and decreased lung CXCL1vs. WT animals. Mediators of tissue remodeling (TIMP1, MMP-8, MMP-9) were also decreased in the LPS-exposed Acod1-/- mice, with MMP-9 also reduced in ODE-exposed Acod1-/- mice. Lung function assessments demonstrated a blunted response to LPS-induced airway hyperresponsiveness in Acod1-/- animals. Conclusion: Acodl is robustly upregulated in the lungs following LPS exposure and encodes a key immunometabolic regulator. ACOD1 mediates the proinflammatory response to acute inhaled environmental LPS and organic dust exposure-induced lung inflammation. [ABSTRACT FROM AUTHOR]

Purpose We evaluated associations between adiponectin and the risk of diabetes among patients with rheumatoid arthritis (RA), a systemic inflammatory disease associated with metabolic disturbance. Methods This prospective cohort study included adults with RA from the Veterans Affairs Rheumatoid Arthritis Registry. Adiponectin and inflammatory cytokines/chemokines were measured at enrollment on stored serum samples. Adiponectin levels were categorized, and clinical variables were described across categories (<10 μg/mL; 10-40 μg/mL; >40 μg/mL). Multivariable Cox proportional hazard models evaluated associations between adiponectin and incident diabetes adjusting for age, sex, race, smoking status, body mass index (BMI), disease-modifying therapy use, calendar year, and comorbidity. Testing for modification of effect in the context of elevated cytokines/chemokines was performed. Results Among 2595 patients included in the analysis, those with adiponectin levels >40 μg/mL (N = 379; 15%) were older and had lower BMI. There were 125 new cases of diabetes among 1689 patients without prevalent disease at enrollment. There was an inverse association between adiponectin and incident diabetes; however, the association was positive among patients with adiponectin levels >40 μg/mL. Patients with levels >40 μg/mL were at higher risk compared to those with levels 10-40 μg/mL (HR: 1.70 [1.34, 2.16] P <.001). Those with adiponectin levels >40 μg/mL had significantly higher levels of inflammatory cytokines with evidence of a modified effect of adiponectin on diabetes risk in the setting of inflammation. Conclusion The relationship between adiponectin and incident diabetes risk is U-shaped in RA. Patients with very high adiponectin levels have greater systemic inflammation and an altered relationship between adiponectin and diabetes risk. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study is to determine the associations of protein‐specific anti–malondialdehyde‐acetaldehyde (MAA) antibodies with prevalent and incident rheumatoid arthritis–interstitial lung disease (RA‐ILD). Methods: Within a multicenter, prospective cohort of US veterans with RA, RA‐ILD was validated by medical record review of clinical diagnoses, chest imaging, and pathology. Serum antibodies to MAA‐albumin, MAA‐collagen, MAA‐fibrinogen, and MAA‐vimentin (IgA, IgM, and IgG) were measured by a standardized enzyme‐linked immunosorbent assay. Associations of anti‐MAA antibodies with prevalent and incident RA‐ILD were assessed using multivariable regression models adjusting for established RA‐ILD risk factors. Results: Among 2,739 participants with RA (88% male, mean age of 64 years), there were 114 with prevalent and 136 with incident RA‐ILD (average time to diagnosis: 6.6 years). Higher IgM anti–MAA‐collagen (per 1 SD: adjusted odds ratio [aOR] 1.28, 95% confidence interval [CI] 1.02–1.61), IgA anti–MAA‐fibrinogen (aOR 1.48, 95% CI 1.14–1.92), and IgA (aOR 1.78, 95% CI 1.34–2.37) and IgG (aOR 1.48, 95% CI 1.14–1.92) anti–MAA‐vimentin antibodies were associated with prevalent RA‐ILD. In incident analyses, higher IgA (per one SD: adjusted hazards ratio [aHR] 1.40, 95% CI 1.11–1.76) and IgM (aHR 1.29, 95% CI 1.04–1.60) anti–MAA‐albumin antibody concentrations were associated with increased ILD risk. Participants with IgA (aHR 2.13, 95% CI 1.16–3.90) or IgM (aHR 1.98, 95% CI 1.08–3.64) anti–MAA‐albumin antibody concentrations in the highest quartile had an approximately two‐fold increased risk of incident RA‐ILD. Across all isotypes, anti–MAA‐fibrinogen, anti–MAA‐collagen, and anti–MAA‐vimentin antibodies were not significantly associated with incident RA‐ILD. Conclusion: Protein‐specific anti‐MAA antibodies to collagen, fibrinogen, and vimentin were associated with prevalent RA‐ILD. IgA and IgM anti–MAA‐albumin antibodies were associated with a higher risk of incident RA‐ILD. These findings suggest that MAA modifications and resultant immune responses may contribute to RA‐ILD pathogenesis. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the associations of plasma matrix metalloproteinases (MMPs) with prevalent and incident interstitial lung disease (ILD) in people with rheumatoid arthritis (RA). Methods: Within a multicenter, prospective cohort of US veterans with RA, we performed a cross‐sectional study of prevalent ILD and cohort study of incident ILD. ILD diagnoses were validated by medical record review of provider diagnoses and chest imaging and/or pathology reports. MMP‐1, 3, 7, and 9 concentrations were measured in plasma samples, then standardized and categorized into quartiles. The associations of MMPs with prevalent and incident ILD were assessed with logistic (prevalent) and Cox (incident) regression models adjusted for RA‐ILD risk factors. Results: Among 2,312 participants (88.9% male; mean age 63.8 years), 96 had prevalent ILD. Incident ILD developed in 130 participants over 17,378 person‐years of follow‐up (crude incidence rate 7.5/1,000 person‐years). Participants with the highest quartile of MMP‐7 concentrations had a nearly four‐fold increased odds of prevalent ILD (adjusted odds ratio 3.78 [95% confidence interval (95% CI) 1.86–7.65]) and over two‐fold increased risk of incident ILD (adjusted hazard ratio 2.33 [95% CI 1.35–4.02]). Higher MMP‐9 concentrations were also associated with prevalent and incident ILD, as well as negatively correlated with forced vital capacity among those with prevalent ILD (r = −0.30, P = 0.005). Conclusion: MMP‐7 and MMP‐9 were strongly associated with both prevalent and incident ILD in this large, multicenter RA cohort after adjustment for other RA‐ILD risk factors. These population‐level findings further support a potential pathogenic role for MMPs in RA‐ILD and suggest that their measurement could facilitate RA‐ILD risk stratification. [ABSTRACT FROM AUTHOR]

Objectives To quantify associations of serum alarmins with risk of rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Methods Using serum collected at enrolment, three alarmins (IL-33, thymic stromal lymphopoietin [TSLP] and IL-25) were measured in a multicentre prospective RA cohort. ILD was classified using systematic medical record review. Cross-sectional associations of log-transformed (IL-33, TSLP) or quartile (IL-25) values with RA-ILD at enrolment (prevalent RA-ILD) were examined using logistic regression, while associations with incident RA-ILD developing after enrolment were examined using Cox proportional hazards. Covariates in multivariate models included age, sex, race, smoking status, RA disease activity score and anti-cyclic citrullinated antibody positivity. Results Of 2835 study participants, 115 participants (4.1%) had prevalent RA-ILD at baseline and an additional 146 (5.1%) developed incident ILD. There were no associations between serum alarmin concentrations and prevalent ILD in unadjusted or adjusted logistic regression models. In contrast, there was a significant inverse association between IL-33 concentration and the risk of developing incident RA-ILD in unadjusted (hazard ratio [HR] 0.73 per log-fold increase; 95% CI: 0.57, 0.95; P  = 0.018) and adjusted (HR 0.77; 95% CI: 0.59, 1.00; P  = 0.047) models. No significant associations of TSLP or IL-25 with incident ILD were observed. Conclusion In this study, we observed a significant inverse association between serum IL-33 concentration and the risk of developing incident RA-ILD, but no associations with prevalent ILD. Additional investigation is required to better understand the mechanisms driving this relationship and how serum alarmin IL-33 assessment might contribute to clinical risk stratification in patients with RA. [ABSTRACT FROM AUTHOR]

Abstract Introduction A deletion polymorphism in glutathione S-transferase Mu-1 (GSTM1-null) has previously been implicated to play a role in rheumatoid arthritis (RA) risk and progression, although no prior investigations have examined its associations with anticitrullinated protein antibody (ACPA) positivity. The purpose of this study was to examine the associations of GSTM1-null with ACPA positivity in RA and to assess for evidence of interaction between GSTM1 and HLA-DRB1 shared epitope (SE). Methods Associations of GSTM1-null with ACPA positivity were examined separately in two RA cohorts, the Veterans Affairs Rheumatoid Arthritis (VARA) registry (n = 703) and the Study of New-Onset RA (SONORA; n = 610). Interactions were examined by calculating an attributable proportion (AP) due to interaction. Results A majority of patients in the VARA registry (76%) and SONORA (69%) were positive for ACPA with a similar frequency of GSTM1-null (53% and 52%, respectively) and HLA-DRB1 SE positivity (76% and 71%, respectively). The parameter of patients who had ever smoked was more common in the VARA registry (80%) than in SONORA (65%). GSTM1-null was significantly associated with ACPA positivity in the VARA registry (odds ratio (OR), 1.45; 95% confidence interval (CI), 1.02 to 2.05), but not in SONORA (OR, 1.00; 95% CI, 0.71 to 1.42). There were significant additive interactions between GSTM1 and HLA-DRB1 SE in the VARA registry (AP, 0.49; 95% CI, 0.21 to 0.77; P < 0.001) in ACPA positivity, an interaction replicated in SONORA (AP, 0.38; 95% CI, 0.00 to 0.76; P = 0.050). Conclusions This study is the first to show that the GSTM1-null genotype, a common genetic variant, exerts significant additive interaction with HLA-DRB1 SE on the risk of ACPA positivity in RA. Since GSTM1 has known antioxidant functions, these data suggest that oxidative stress may be important in the development of RA-specific autoimmunity in genetically susceptible individuals.

Objectives To determine whether an expanded antigen-specific ACPA profile predicts changes in disease activity in patients with RA initiating biologics. Methods The study included participants from a prospective, non-randomized, observational RA cohort. For this sub-study, treatment groups of interest included biologic-naïve initiating anti-TNF, biologic-exposed initiating non-TNF, and biologic-naïve initiating abatacept. ACPAs to 25 citrullinated peptides were measured using banked enrolment serum. Principal component analysis (PCA) was performed and associations of resulting principal component (PC) scores (in quartiles) and anti-CCP3 antibody (≤15, 16–250 or >250 U/ml) with EULAR (good/moderate/none) treatment response at 6 months were examined using adjusted ordinal regression models. Results Participants (n  = 1092) had a mean age of 57 (13) years and 79% were women. At 6 months, 68.5% achieved a moderate/good EULAR response. There were three PCs that cumulatively explained 70% of variation in ACPA values. In models including the three components and anti-CCP3 antibody category, only PC1 and PC2 were associated with treatment response. The highest quartile for PC1 (odds ratio [OR] 1.76; 95% CI: 1.22, 2.53) and for PC2 (OR 1.74; 95% CI: 1.23, 2.46) were associated with treatment response after multivariable adjustment. There was no evidence of interaction between PCs and treatment group in EULAR responses (P -value for interaction >0.1). Conclusion An expanded ACPA profile appears to be more strongly associated with biologic treatment response in RA than commercially available anti-CCP3 antibody levels. However, further enhancements to PCA will be needed to effectively prioritize between different biologics available for the treatment of RA. [ABSTRACT FROM AUTHOR]