Vassallo, Robert

Exhausted-like CD8 + resident memory T cells in the lung limit immune activation–driven fibrosis.

Rheumatoid arthritis (RA) is a common chronic autoimmune disorder that characteristically causes joint inflammation and damage. In addition, many patients develop extraarticular manifestations which may cause significant comorbidity and premature mortality.Some respiratory tract involvement of the upper and lower airways and parenchymal disease features are unique to RA, including cricoarytenoid arthritis and RA pulmonary nodulosis, and others, especially the interstitial parenchymal involvement, occur in many other idiopathic and autoimmune diseases. The pathophysiology of lung disease is not well understood. Rheumatoid lung disease may even predate the onset of joint disease, and could be triggered by chronic airway and alveolar epithelial injury. Chronic systemic inflammation and risk factors such as cigarette smoking, infection, host genetics, and immune dysregulation are contributors. Treatment of the respiratory disease is directed at reducing the systemic inflammation of RA. Less well understood is the management of the interstitial lung disease of RA, for which antifibrotic and immune suppressive agents may be helpful. The management of RA-related lung disease is perhaps the major remaining hurdle in reduction of the disease burden related to extraarticular manifestations of this disease.

ObjectiveRheumatoid arthritis (RA) is postulated to originate at mucosal surfaces, particularly the airway mucosa. To investigate this hypothesis, we determined the association between RA and asthma, passive smoke exposure, and age at start of smoking.MethodsFor this case–control study, we identified 1,023 cases of RA (175 incident) within a single‐center biobank population, using a rules‐based algorithm that combined self‐report with 2 diagnostic codes. Exposures were self‐reported on biobank questionnaires. Logistic regression models were used to calculate the association of exposures with RA, adjusting for potential confounders. Odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated.ResultsAfter adjustment for allergies, urban environment, and passive smoke exposure, asthma was found to be associated with RA in the full cohort (OR 1.28 [95% CI 1.04–1.58; P = 0.02]) but not the incident RA cohort (OR 1.17 [95% CI 0.66–2.06; P = 0.60]). History of allergic disease was associated with RA in both the full cohort (OR 1.30 [95% CI 1.12–1.51; P < 0.001]) and the incident RA cohort (OR 1.61 [95% CI 1.11–2.33; P = 0.01]), especially food allergy, which was significantly associated with RA in the full cohort (OR 1.38 [95% CI 1.08–1.75; P = 0.01]) and showed a trend toward significance in the incident RA cohort (OR 1.83 [95% CI 0.97–3.45; P = 0.06]). Passive smoke exposure at home or work was not associated with RA. Finally, age at start of smoking was not associated with increased odds of developing RA in either the full cohort (OR 1.03 [95% CI 1.00–1.06; P = 0.03]) or the incident RA cohort (OR 1.00 [95% CI 0.92–1.08; P = 0.98]).ConclusionAsthma and allergies may be associated with increased risk of RA. Passive smoke exposure and early age at start of smoking do not appear to influence risk of RA.

Interleukin (IL)-17 is a T helper 17 cytokine implicated in the pathogenesis of many autoimmune diseases, including rheumatoid arthritis (RA). Although IL-17A has a well-established role in murine pulmonary fibrosis models, its role in the tissue remodeling and fibrosis occurring in idiopathic pulmonary fibrosis (IPF) and RA-associated interstitial lung disease (RA-ILD) is not very well defined. To address this question, we utilized complimentary studies to determine responsiveness of human normal and pathogenic lung fibroblasts to IL-17A and used lung biopsies acquired from patients with IPF and RA-ILD to determine IL-17A receptor (IL-17RA) expression. Both normal and pathogenic IPF lung fibroblasts express functional IL-17RA and respond to IL-17A stimulation with cell proliferation, generation of extracellular matrix (ECM) proteins, and induction of myofibroblast transdifferentiation. Small interfering RNA (siRNA) silencing of IL-17RA attenuated this fibroblast response to IL-17A on ECM production. These fibroblast responses to IL-17A are dependent on NF-κB-mediated signaling. In addition, inhibiting Janus activated kinase (JAK) 2 by either siRNA or a selective pharmacological inhibitor, AZD1480—but not a JAK1/JAK3 selective inhibitor, tofacitinib—also significantly reduced this IL-17A-induced fibrogenic response. Lung biopsies of RA-ILD patients demonstrate significantly higher IL-17RA expression in areas of fibroblast accumulation and fibrosis, compared with either IPF or normal lung tissue. These observations support a direct role for IL-17A in lung fibrosis that may be particularly relevant in the context of RA-ILD.

Context.— Pulmonary hypertension (PHT) is a complication of pulmonary Langerhans cell histiocytosis (PLCH); however, the pathogenesis remains largely unknown. Few studies have evaluated histopathologic changes in pulmonary arteries (PAs) of patients with PLCH; systematic quantification of arterial remodeling has yet to be undertaken. Objective.— To quantify the extent of arterial remodeling among patients with PLCH through morphometry and to correlate these results with pertinent clinical parameters. Design.— Patients with PLCH were identified from institutional files (1995–2015) along with age-, sex-, and smoking status–matched controls. Morphometric analysis of intimal and medial thickness of small to medium PAs was performed in patients with PLCH (within PLCH lesions [lesional] and away from PLCH lesions [nonlesional]) and controls. Paired measures were compared with Wilcoxon signed rank tests. Results.— Twenty-five patients with PLCH (14 men: median age, 46 years; interquartile range, 37–55 years) and 25 controls were included. The lesional arteries of patients with PLCH demonstrated thicker PA intima and media than controls (P &lt; .001 and P &lt; .001, respectively), as did PLCH nonlesional arteries compared to controls (P &lt; .001 and P &lt; .001, respectively). The PA intima and media were thicker within the PLCH lesions than nonlesional arteries (P = .02 and P = .002, respectively). Patients with PLCH-related PHT had a worse prognosis than those without PHT (P = .04; hazard ratio, 4.5 [1.1, 22.2]). Echocardiography parameters including right atrial size (P = .007), estimated right atrial pressure (P = .01), and right ventricular systolic pressure (P = .01) were inversely associated with survival. Conclusions.— Our findings suggest that factors other than direct vascular obstruction or inflammatory cell infiltration contribute, at least in part, to the vascular remodeling in PLCH.

ABSTRACT Myofibroblasts play key roles in wound healing and pathological fibrosis. Here, we used an RNAi screen to characterize myofibroblast regulatory genes, using a high-content imaging approach to quantify α-smooth muscle actin stress fibers in cultured human fibroblasts. Screen hits were validated on physiological compliance hydrogels, and selected hits tested in primary fibroblasts from patients with idiopathic pulmonary fibrosis. Our RNAi screen led to the identification of STAT3 as an essential mediator of myofibroblast activation and function. Strikingly, we found that STAT3 phosphorylation, while responsive to exogenous ligands on both soft and stiff matrices, is innately active on a stiff matrix in a ligand/receptor-independent, but ROCK- and JAK2-dependent fashion. These results demonstrate how a cytokine-inducible signal can become persistently activated by pathological matrix stiffening. Consistent with a pivotal role for this pathway in driving persistent fibrosis, a STAT3 inhibitor attenuated murine pulmonary fibrosis when administered in a therapeutic fashion after bleomycin injury. Our results identify novel genes essential for the myofibroblast phenotype, and point to STAT3 as an important target in pulmonary fibrosis and other fibrotic diseases.

Abstract Acute eosinophilic pneumonia (AEP) is an uncommon acute respiratory illness of varying severity that includes presentation as acute respiratory distress syndrome with fatal outcome. AEP may be idiopathic, but identifiable causes include smoking and other inhalational exposures, medications, and infections. The pathogenesis of AEP is poorly understood but likely varies depending on the underlying cause. Airway epithelial injury, endothelial injury, and release of IL-33 are early events that subsequently promote eosinophil recruitment to the lung; eosinophilic infiltration and degranulation appear to mediate subsequent lung inflammation and associated clinical manifestations. Crucial for the diagnosis are the demonstration of pulmonary eosinophilia in the BAL fluid and the exclusion of other disease processes that can present with acute pulmonary infiltrates. Although peripheral blood eosinophilia at initial presentation may be a clue in suggesting the diagnosis of AEP, it may be absent or delayed, especially in smoking-related AEP. Optimal management of AEP depends on the recognition and elimination of the underlying cause when identifiable. The cessation of the exposure to the inciting agent (e.g., smoking), and glucocorticoids represent the mainstay of treating AEP of noninfectious origin. If AEP is recognized and treated in a timely manner, the prognosis is generally excellent, with prompt and complete clinical recovery, even in those patients manifesting acute respiratory failure.