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Pulmonary fibrosis is characterized by the accumulation of myofibroblasts in the lung and progressive tissue scarring. Fibroblasts exist across a spectrum of states, from quiescence in health to activated myofibroblasts in the setting of injury. Highly activated myofibroblasts have a critical role in the establishment of fibrosis as the predominant source of type 1 collagen and profibrotic mediators. Myofibroblasts are also highly contractile cells and can alter lung biomechanical properties through tissue contraction. Inhibiting signaling pathways involved in myofibroblast activation could therefore have significant therapeutic value. One of the ways myofibroblast activation occurs is through activation of the Rho/myocardin-related transcription factor (MRTF)/serum response factor (SRF) pathway, which signals through intracellular actin polymerization. However, concerns surrounding the pleiotropic and ubiquitous nature of these signaling pathways have limited the translation of inhibitory drugs. Herein, we demonstrate a novel therapeutic antifibrotic strategy using myofibroblast-targeted nanoparticles containing a MTRF/SRF pathway inhibitor (CCG-1423), which has been shown to block myofibroblast activation in vitro. Myofibroblasts were preferentially targeted via the angiotensin 2 receptor, which has been shown to be selectively upregulated in animal and human studies. These nanoparticles were nontoxic and accumulated in lung myofibroblasts in the bleomycin-induced mouse model of pulmonary fibrosis, reducing the number of these activated cells and their production of profibrotic mediators. Ultimately, in a murine model of lung fibrosis, a single injection of these drugs containing targeted nanoagents reduced fibrosis as compared with control mice. This approach has the potential to deliver personalized therapy by precisely targeting signaling pathways in a cell-specific manner, allowing increased efficacy with reduced deleterious off-target effects.

Asthma is a chronic disease most commonly associated with allergy and type 2 inflammation. However, the mechanisms that link airway inflammation to the structural changes that define asthma are incompletely understood. Using a human model of allergen-induced asthma exacerbation, we compared the lower airway mucosa in allergic asthmatics and allergic non-asthmatic controls using single-cell RNA sequencing. In response to allergen, the asthmatic airway epithelium was highly dynamic and up-regulated genes involved in matrix degradation, mucus metaplasia, and glycolysis while failing to induce injury-repair and antioxidant pathways observed in controls. IL9 -expressing pathogenic T H 2 cells were specific to asthmatic airways and were only observed after allergen challenge. Additionally, conventional type 2 dendritic cells (DC2 that express CD1C ) and CCR2 -expressing monocyte-derived cells (MCs) were uniquely enriched in asthmatics after allergen, with up-regulation of genes that sustain type 2 inflammation and promote pathologic airway remodeling. In contrast, allergic controls were enriched for macrophage-like MCs that up-regulated tissue repair programs after allergen challenge, suggesting that these populations may protect against asthmatic airway remodeling. Cellular interaction analyses revealed a T H 2–mononuclear phagocyte–basal cell interactome unique to asthmatics. These pathogenic cellular circuits were characterized by type 2 programming of immune and structural cells and additional pathways that may sustain and amplify type 2 signals, including TNF family signaling, altered cellular metabolism, failure to engage antioxidant responses, and loss of growth factor signaling. Our findings therefore suggest that pathogenic effector circuits and the absence of proresolution programs drive structural airway disease in response to type 2 inflammation.

Idiopathic pulmonary fibrosis is a progressive lung disease with limited therapeutic options that is characterized by pathological fibroblast activation and aberrant lung remodeling with scar formation. YAP (Yes-associated protein) is a transcriptional coactivator that mediates mechanical and biochemical signals controlling fibroblast activation. We previously identified HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibitors (statins) as YAP inhibitors based on a high-throughput small-molecule screen in primary human lung fibroblasts. Here we report that several Aurora kinase inhibitors were also identified from the top hits of this screen. MK-5108, a highly selective inhibitor for AURKA (Aurora kinase A), induced YAP phosphorylation and cytoplasmic retention and significantly reduced profibrotic gene expression in human lung fibroblasts. The inhibitory effect on YAP nuclear translocation and profibrotic gene expression is specific to inhibition of AURKA, but not Aurora kinase B or C, and is independent of the Hippo pathway kinases LATS1 and LATS2 (Large Tumor Suppressor 1 and 2). Further characterization of the effects of MK-5108 demonstrate that it inhibits YAP nuclear localization indirectly via effects on actin polymerization and TGFβ (Transforming Growth Factor β) signaling. In addition, MK-5108 treatment reduced lung collagen deposition in the bleomycin mouse model of pulmonary fibrosis. Our results reveal a novel role for AURKA in YAP-mediated profibrotic activity in fibroblasts and highlight the potential of small-molecule screens for YAP inhibitors for identification of novel agents with antifibrotic activity.

Smoking and HIV-1 infection are risk factors for COPD, which is among the most common comorbid conditions in people living with HIV-1. HIV-1 infection leads to persistent expansion of CD8+ T cells, and CD8+ T cell-mediated inflammation has been implicated in COPD pathogenesis. In this study, we investigated the effects of HIV-1 infection and smoking on T cell dynamics in patients at risk of COPD. Bronchoalveolar lavage (BAL), endobronchial brushings and blood from HIV-1 infected and uninfected non-smokers and smokers were analyzed by flow cytometry, and lungs were imaged by computed tomography. Chemokines were measured in BAL fluid, and CD8+ T cell chemotaxis in the presence of cigarette smoke extract was assessed in vitro. HIV-1 infection increased CD8+ T cells in the BAL, but this increase was abrogated by smoking. Smokers had reduced BAL levels of the T cell-recruiting chemokines CXCL10 and CCL5, and cigarette smoke extract inhibited CXCL10 and CCL5 production by macrophages and CD8+ T cell transmigration in vitro. In contrast to the BAL, CD8+ T cells in endobronchial brushings were increased in HIV-1 infected smokers, driven by an accumulation of effector memory T cells in the airway mucosa and an increase in tissue resident memory T cells. Mucosal CD8+ T cell numbers inversely correlated with lung aeration, suggesting an association with inflammation and remodeling. HIV-1 infection and smoking lead to retention of CD8+ T cells within the airway mucosa.

Tobacco smoking doubles the risk of active tuberculosis (TB) and accounts for up to 20% of all active TB cases globally. How smoking promotes lung microenvironments permissive toMycobacterium tuberculosis(Mtb) growth remains incompletely understood. We investigated primary bronchoalveolar lavage cells from current- and never-smokers by performing single-cell RNA-sequencing (scRNA-seq), flow cytometry, and functional assays. We observed enrichment of immature inflammatory monocytes in the lungs of smokers compared to non-smokers. These monocytes exhibited phenotypes consistent with recent recruitment from blood, ongoing differentiation, increased activation, and states similar to those with chronic obstructive pulmonary disease (COPD). Using integrative scRNA-seq and flow cytometry, we identify CD93 as a marker for a subset of these newly recruited smoking-associated lung monocytes and further provide evidence that recruitment of monocytes into the lung is mediated by CCL11 binding to CCR2. We also show that these cells exhibit elevated inflammatory responses upon exposure toMtband accelerated intracellular growth ofMtbcompared to mature macrophages. This elevatedMtbgrowth could be inhibited with an anti-inflammatory small molecule, providing a direct connection between smoking-induced pro-inflammatory states and permissiveness toMtbgrowth. Our findings suggest a model in which smoking leads to recruitment of immature inflammatory monocytes from the periphery to the lung via CCL11-CCR2 interactions, which results in the accumulation of theseMtbpermissive cells in the airway. This work defines how smoking may lead to increased susceptibility toMtband identifies novel host-directed therapies to reduce the burden of TB among those who smoke.One Sentence SummaryInflammatory monocytes are recruited to the airways of smokers where they may contribute to more rapid growth ofMycobacterium tuberculosisin the lungs.

BACKGROUND: Vaping, including the use of electronic cigarettes (e-cigarettes), has become increasingly prevalent, yet the associated long-term health risks are largely unknown. Given the prevalence of use, particularly among adolescents early in their lifespan, it is vital to understand the potential chronic pathologic sequelae of vaping. METHODS: We present the cases of four patients with chronic lung disease associated with e-cigarette use characterized by clinical evaluation, with pulmonary function tests (PFTs), chest high-resolution computed tomography (HRCT), endobronchial optical coherence tomography (EB-OCT) imaging, and histopathologic assessment. RESULTS: Each patient presented with shortness of breath and chest pain in association with a 3- to 8-year history of e-cigarette use, with mild progressive airway obstruction on PFTs and/or chest HRCT findings demonstrating evidence of air trapping and bronchial wall thickening. EB-OCT imaging performed in two patients showed small airway–centered fibrosis with bronchiolar narrowing and lumen irregularities. The predominant histopathologic feature on surgical lung biopsy was small airway–centered fibrosis, including constrictive bronchiolitis and MUC5AC overexpression in all patients. Patients who ceased vaping had a partial, but not complete, reversal of disease over 1 to 4 years. CONCLUSIONS: After thorough evaluation for other potential etiologies, vaping was considered to be the most likely common causal etiology for all patients due to the temporal association of symptomatic chronic lung disease with e-cigarette use and partial improvement in symptoms after e-cigarette cessation. In this series, we associate the histopathologic pattern of small airway–centered fibrosis, including constrictive bronchiolitis, with vaping, potentially defining a clinical and pathologic entity associated with e-cigarette use. (Funded in part by the National Institutes of Health.)