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The objective of this study was to assess fibrinogen (FIB) comodified with citrulline (CIT) and/or malondialdehyde-acetaldehyde (MAA) initiates macrophage-fibroblast interactions, leading to extracellular matrix (ECM) deposition that characterizes rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Macrophages (Mϕ) were stimulated with native-FIB, FIB-CIT, FIB-MAA, or FIB-MAA-CIT. Supernatants (SNs) [Mϕ-SN (U-937-derived) or MϕP-SN (PBMC-derived)] or direct antigens were coincubated with human lung fibroblasts (HLFs). Gene expression was examined using RT-PCR. ECM deposition was quantified using immunohistochemistry and Western blot; cell signaling mechanisms were delineated. Platelet-derived growth factor (PDGF)-BB and TGF-β were measured in macrophage supernatants, and inhibition studies were performed using Su16f and SB431542, respectively. HLF gene expression of CD36, COL6A3, MMP-9, MMP-10, and MMP-12 was increased following stimulations with Mϕ-SN generated from modified FIB but not from direct antigens. HLF stimulated with MϕP-SNFIB-MAA-CIT derived from patients with RA-ILD resulted in 4- to 30-fold increases in COL6A3 and MMP12 expression; upregulation was greater in HLFs stimulated with MϕP-SN derived from RA-ILD versus controls. HLF exposure to Mϕ-SNFIB-MAA-CIT increased types I/VI collagen deposition versus all other Mϕ-SN groups and was greater than FIB-MAA-CIT stimulation. PDGF-BB and TGF-β signaling had the highest concentrations identified in Mϕ-SNFIB-MAA-CIT and MϕP-SNFIB-MAA-CIT, particularly from RA-ILD-derived cells. PDGF-BB and TGF-β inhibitors, alone and in combination, significantly reduced HLF-mediated ECM deposition from Mϕ-SN stimulations. These results show that comodified fibrinogen activates macrophages to produce PDGF-BB and TGF-β that promotes an aggressive HLF phenotype characterized by increased ECM deposition. These results suggest that targeting CIT and/or MAA modifications or downstream cellular signals could represent novel approaches to RA-ILD treatment. NEW & NOTEWORTHY: This report demonstrates that fibrinogen simultaneously harboring two common posttranslational modifications activates macrophages to secrete platelet-derived growth factor (PDGF)-BB and transforming growth factor (TGF)-β. Resulting cross talk between activated macrophages and human lung fibroblasts leads to marked increases in extracellular matrix deposition. These protein modifications are abundant and colocalize in lung tissues from patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD), and the results suggest that agents targeting citrullination and/or malondialdehyde-acetaldehyde (MAA) adduct formation could represent novel therapeutic strategies. [ABSTRACT FROM AUTHOR]

Objective Although clinical and genetic risk factors have been identified for rheumatoid arthritis-associated interstitial lung disease (RA-ILD), there are no current tools allowing for risk stratification. We sought to develop and validate an ILD risk model in a large, multicentre, prospective RA cohort. Methods Participants in the Veterans Affairs RA (VARA) registry were genotyped for 12 single nucleotide polymorphisms (SNPs) associated with idiopathic pulmonary fibrosis. ILD was validated through systematic record review. A genetic risk score (GRS) was computed from minor alleles weighted by effect size with ILD, using backward selection. The GRS was combined with clinical risk factors within a logistic regression model. Internal validation was completed using bootstrapping, and model performance was assessed by the area under the receiver operating curve (AUC). Results Of 2386 participants (89% male, mean age 69.5 years), 9.4% had ILD. Following backward selection, five SNPs contributed to the GRS. The GRS and clinical factors outperformed clinical factors alone in discriminating ILD (AUC 0.675 vs 0.635, P  < 0.001). The shrinkage-corrected performance for combined and clinical-only models was 0.667 (95% CI 0.628, 0.712) and 0.623 (95% CI 0.584, 0.651), respectively. Twenty percent of the cohort had a combined risk score below a cut-point with >90% sensitivity. Conclusion A clinical and genetic risk model discriminated ILD in a large, multicentre RA cohort better than a clinical-only model, excluding 20% of the cohort from low-yield testing. These results demonstrate the potential utility of a GRS in RA-ILD and support further investigation into individualized risk stratification and screening. [ABSTRACT FROM AUTHOR]

Objective: Increased risk of occupational exposure to bioaerosols has long been recognized in livestock operations including dairy facilities. Spanning the inhalable fraction (0–100 μm), dairy bioaerosols comprise a wide variety of inflammatory components that deposit in the nasopharyngeal region. The resultant inflammatory response from bioaerosol exposure is likely driving the increased prevalence of respiratory disease observed in dairy workers. It is also thought the microbiome of the upper respiratory system may help mediate this inflammation. We investigated the viability of a low-cost hypertonic saline nasal rinse intervention in modulating inflammatory responses in bioaerosol exposed dairy workers and its impact on microbial diversity. Methods: Pre- and post-shift nasal rinses were administered and collected alongside full shift inhalable personal breathing zone (PBZ) samples for each participant for up to 5 consecutive days. Treatment group participants (n = 23) received hypertonic saline rinses while control group participants (n = 22) received normotonic saline rinses. Particulate matter (PM) and endotoxin concentrations were quantified from PBZ samples using gravimetric and enzymatic analytical methods, respectively. Pre- and post-shift rinses were analyzed for pro- and anti-inflammatory markers and microbial diversity using a multiplex assay and 16S rRNA sequencing, respectively. Results: PM and endotoxin concentrations were comparable between groups indicating similar exposures. Post-shift pro-inflammatory markers were significantly higher than pre-shift for IL-13 (p =.047), IL-1β (p <.001), IL-6 (p <.001), IL-8 (p <.001), and TNF-α (p =.024). There was no evidence of a difference in log concentrations between intervention group or day among any of the measured inflammatory markers. Anti-inflammatory IL-10 concentrations increased across the 5 sample days, independent of treatment group suggesting tonicity may not be driving the change. However, this result was not significant (p =.217). Nasal microbiome alpha (within sample) and beta (between sample) diversity metrics did not differ significantly between group or day demonstrating no adverse washout intervention effects. Conclusion: This study provided encouraging results that warrant future research to further evaluate saline nasal rinses as a workplace intervention. [ABSTRACT FROM AUTHOR]

Efficacious therapeutic options capable of resolving inflammatory lung disease associated with environmental and occupational exposures are lacking. This study sought to determine the preclinical therapeutic potential of lung-delivered recombinant interleukin (IL)-10 therapy following acute organic dust exposure in mice. Here, C57BL/6J mice were intratracheally instilled with swine confinement organic dust extract (ODE) (12.5%, 25%, 50% concentrations) with IL-10 (1 μg) treatment or vehicle control intratracheally-administered three times: 5 hr post-exposure and then daily for 2 days. The results showed that IL-10 treatment reduced ODE (25%)-induced weight loss by 66% and 46% at Day 1 and Day 2 post-exposure, respectively. IL-10 treatment reduced ODE (25%, 50%)-induced lung levels of TNFα (–76%, −83% [reduction], respectively), neutrophil chemoattractant CXCL1 (–51%, −60%), and lavage fluid IL-6 (–84%, −89%). IL-10 treatment reduced ODE (25%, 50%)-induced lung neutrophils (–49%, −70%) and recruited CD11cintCD11b+ monocyte-macrophages (–49%, −70%). IL-10 therapy reduced ODE-associated expression of antigen presentation (MHC Class II, CD80, CD86) and inflammatory (Ly6C) markers and increased anti-inflammatory CD206 expression on CD11cintCD11b+ cells. ODE (12.5%, 25%)-induced lung pathology was also reduced with IL-10 therapy. In conclusion, the studies here showed that short-term, lung-delivered IL-10 treatment induced a beneficial response in reducing inflammatory consequences (that were also associated with striking reduction in recruited monocyte-macrophages) following acute complex organic dust exposure. [ABSTRACT FROM AUTHOR]

Dairy workers experience a high degree of bioaerosol exposure, composed of an array of biological and chemical constituents, which have been tied to adverse health effects. A better understanding of the variation in the magnitude and composition of exposures by task is needed to inform worker protection strategies. To characterize the levels and types of exposures, 115 dairy workers grouped into three task categories on nine farms in the high plains Western United States underwent personal monitoring for inhalable dust, endotoxin, 3-hydroxy fatty acids (3-OHFA), muramic acid, ergosterol, and ammonia through one work shift. Eighty-nine percent of dairy workers were exposed to endotoxin at concentrations exceeding the recommended exposure guidelines (adjusted for a long work shift). The proportion of workers with exposures exceeding recommended guidelines was lower for inhalable dust (12%), and ammonia (1%). Ergosterol exposures were only measurable on 28% of samples, primarily among medical workers and feed handlers. Milking parlor workers were exposed to significantly higher inhalable dust, endotoxin, 3-OHFA, ammonia, and muramic acid concentrations compared to workers performing other tasks. Development of large modern dairies has successfully made progress in reducing worker exposures and lung disease prevalence. However, exposure to endotoxin, dust, and ammonia continues to present a significant risk to worker health on North American dairies, especially for workers in milking parlors. This study was among the first to concurrently evaluate occupational exposure to assayable endotoxin (lipid A), 3-hydroxy fatty acids or 3-OHFA (a chemical measure of cell bound and noncell-bound endotoxins), muramic acid, ergosterol, and ammonia among workers on Western U.S. dairies. There remains a need for cost-effective, culturally acceptable intervention strategies integrated in OHS Risk Management and production systems to further optimize worker health and farm productivity.

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]

SARS-CoV-2, the causative agent of the COVID-19 pandemic, has had a global impact, affecting millions over the last three years. Pre-existing lung diseases adversely affect the prognosis of infected COVID-19 patients, and agricultural workers routinely exposed to inhalable organic dusts have substantial increased risk for developing chronic lung diseases. In previous studies, we characterized the protein kinase C (PKC)-dependent airway inflammation mediated by organic dust extract (ODE) derived from dust collected from swine confinement facilities in in vitro and in vivo models. Here, we studied the effect of ODE on SARS-CoV-2 pseudoviral infection in mice and human bronchial epithelial cells (BEAS-2B). In wild-type (WT) and transgenic mice expressing the human angiotensin I-converting enzyme 2 (ACE2) receptor (SARS-CoV-2 entry receptor), ODE increased ACE2 shedding by ADAM-17 in the lungs. After repeated ODE treatments, the increased soluble ACE2 correlated to higher pseudovirus titer in the mouse lungs. In the human bronchial epithelial cells, ODE augmented PKCα activity in WT cells, and membrane ACE2 expression was diminished in PKCα-dominant negative cells. Unlike in the mice, increasing membrane ACE2 levels by treating with PKCα or ADAM-17 inhibitors and a low dose of ODE enhanced pseudoviral entry in vitro. Following viral entry, IL-8 secretion by the cells was diminished in a PKCα- and ADAM-17-independent manner. Together, the complex mechanisms involved in the synergistic effects of agricultural dust and SARS-CoV-2 highlight the importance of studying dust-mediated changes to immunity against circulating pathogens. [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]