Lung Resident Cells Research Articles

Intrinsically altered lung-resident γδT cells control lung melanoma by producing interleukin-17A in the elderly.

Cancer is an age‐associated disease, potentially related to the altered immune system of elderly individuals. However, cancer has gradually decreased incidence in the eldest globally such as the most common lung cancer, the mechanisms of which remain to be elucidated. In this study, it was found that the number of lung‐resident γδT cells was significantly increased with altered gene expression in aged mice (20–24 months) versus young mice (10–16 weeks). Aged lung Vγ4+ and Vγ6+ γδT cells predominantly produced interleukin‐17A (IL‐17A), resulting in increased levels in the serum and lungs. Moreover, the aged mice exhibited smaller tumors and reduced numbers of tumor foci in the lungs after challenge with intravenous injection of B16/F10 melanoma cells compared with the young mice. Aged lung Vγ4+ and Vγ6+ γδT cells were highly cytotoxic to B16/F10 melanoma cells with higher expression levels of CD103. The markedly longer survival of the challenged aged mice was dependent on γδT17 cells, since neutralization of IL‐17A or depletion of indicated γδT cells significantly shortened the survival time. Consistently, supplementation of IL‐17A significantly enhanced the survival time of young mice with lung melanoma. Furthermore, the anti‐tumor activity of aged lung γδT17 cells was not affected by alterations in the load and composition of commensal microbiota, as demonstrated through co‐housing of the aged and young mice. Intrinsically altered lung γδT17 cells underlying age‐dependent changes control lung melanoma, which will help to better understand the lung cancer progression in the elderly and the potential use of γδT17 cells in anti‐tumor immunotherapy.

Electronic cigarettes disrupt lung lipid homeostasis and innate immunity independent of nicotine

Electronic nicotine delivery systems (ENDS) or e-cigarettes have emerged as a popular recreational tool among adolescents and adults. Although the use of ENDS is often promoted as a safer alternative to conventional cigarettes, few comprehensive studies have assessed the long-term effects of vaporized nicotine and its associated solvents, propylene glycol (PG) and vegetable glycerin (VG). Here, we show that compared with smoke exposure, mice receiving ENDS vapor for 4 months failed to develop pulmonary inflammation or emphysema. However, ENDS exposure, independent of nicotine, altered lung lipid homeostasis in alveolar macrophages and epithelial cells. Comprehensive lipidomic and structural analyses of the lungs revealed aberrant phospholipids in alveolar macrophages and increased surfactant-associated phospholipids in the airway. In addition to ENDS-induced lipid deposition, chronic ENDS vapor exposure downregulated innate immunity against viral pathogens in resident macrophages. Moreover, independent of nicotine, ENDS-exposed mice infected with influenza demonstrated enhanced lung inflammation and tissue damage. Together, our findings reveal that chronic e-cigarette vapor aberrantly alters the physiology of lung epithelial cells and resident immune cells and promotes poor response to infectious challenge. Notably, alterations in lipid homeostasis and immune impairment are independent of nicotine, thereby warranting more extensive investigations of the vehicle solvents used in e-cigarettes.

IRF4-dependent dendritic cells regulate CD8+ T-cell differentiation and memory responses in influenza infection.

Acute respiratory disease caused by influenza viruses is imperfectly mitigated by annual vaccination to select strains. Development of vaccines that elicit lung-resident memory CD8+ T cells (TRM) would offer more universal protection to seasonal and emerging pandemic viruses. Understanding how lung-resident dendritic cells (DCs) regulate TRM differentiation would be an important step in this process. Here, we used CD11c-cre-Irf4f/f (KO) mice, which lack lung-resident IRF4-dependent CD11b+CD24hi DCs and show IRF4 deficiency in other lung cDC subsets, to determine if IRF4-expressing DCs regulate CD8+ memory precursor cells and TRM during influenza A virus (IAV) infection. KO mice showed defective CD8+ T cell memory, stemming from a deficit of T regulatory cells and memory precursor cells with decreased Foxo1 expression. Transfer of wild-type CD11b+CD24hi DCs into KO mice restored CD8+ memory precursor cell numbers to wild-type levels. KO mice recovered from a primary infection harbored reduced numbers of CD8+ TRM and showed deficient expansion of IFNγ+CD8+ T cells and increased lung pathology upon challenge with heterosubtypic IAV. Thus, vaccination strategies that harness the function of IRF4-dependent DCs could promote the differentiation of CD8+ TRM during IAV infection.

Indiscriminate nature of lung resident CD8+ TRM cells reactivation and their varied reactivation profiles

Abstract CD8+ tissue resident memory (TRM) cells are poised at the portals of infection and confer immediate protection upon reinfection. Despite the critical role of CD8+ TRM cells in long-term protective immunity, the precise mechanics governing their reactivation in-situ are unclear. Seminal work by Leo Lefrançois' group showed that circulating (TCIRC) memory CD8+ T cell depends on CD11c+ antigen-presenting cells (APCs) for reactivation, however, TRM cells are reactivated within peripheral tissues, raising the question of whether the same principle is conserved. We examined this question, focusing on influenza infection, because APCs in the lung are well-defined and lung-resident TRM cells are critical for heterologous immunity to influenza. Using a TCR transgenic Nur77 reporter to delineate TCR-specific from bystander activation in CD8+ TRM cells, we characterized the superior reactivation kinetics in CD8+ TRM cell compared to CD8+ TCIRC. We also identified unique TCR-specific signatures and bystander-specific signatures in the kinetics of CD8+ TRM cells and TCIRC cells reactivation respectively. While we observed the strict requirement for CD11c+APCs in TCR-driven CD8+ TCIRC reactivation, CD8+ TRM cells exhibit promiscuity in their interactions with antigen-presenting partners in that they can be reactivated by both hematopoetic and non-hematopoetic cells. This study explains how the anatomical location of CD8+ TRM cells can confer unique advantage by demonstrating their superior reactivation kinetics and the indiscriminate nature of CD8+ TRM cell reactivation as well as showcasing the transcription profiles of TRM and TCIRC cells following different modes of activation.

PPAR-γ in Macrophages Limits Pulmonary Inflammation and Promotes Host Recovery following Respiratory Viral Infection.

Alveolar macrophages (AM) play pivotal roles in modulating host defense, pulmonary inflammation, and tissue injury following respiratory viral infections. However, the transcriptional regulation of AM function during respiratory viral infections is still largely undefined. Here we have screened the expression of 84 transcription factors in AM in response to influenza A virus (IAV) infection. We found that the transcription factor PPAR-γ was downregulated following IAV infection in AM through type I interferon (IFN)-dependent signaling. PPAR-γ expression in AM was critical for the suppression of exaggerated antiviral and inflammatory responses of AM following IAV and respiratory syncytial virus (RSV) infections. Myeloid PPAR-γ deficiency resulted in enhanced host morbidity and increased pulmonary inflammation following both IAV and RSV infections, suggesting that macrophage PPAR-γ is vital for restricting severe host disease development. Using approaches to selectively deplete recruiting monocytes, we demonstrate that PPAR-γ expression in resident AM is likely important in regulating host disease development. Furthermore, we show that PPAR-γ was critical for the expression of wound healing genes in AM. As such, myeloid PPAR-γ deficiency resulted in impaired inflammation resolution and defective tissue repair following IAV infection. Our data suggest a critical role of PPAR-γ expression in lung macrophages in the modulation of pulmonary inflammation, the development of acute host diseases, and the proper restoration of tissue homeostasis following respiratory viral infections.IMPORTANCE Respiratory viral infections, like IAV and respiratory syncytial virus (RSV) infections, impose great challenges to public health. Alveolar macrophages (AM) are lung-resident immune cells that play important roles in protecting the host against IAV and RSV infections. However, the underlying molecular mechanisms by which AM modulate host inflammation, disease development, and tissue recovery are not very well understood. Here we identify that PPAR-γ expression in AM is crucial to suppress pulmonary inflammation and diseases and to promote fast host recovery from IAV and RSV infections. Our data suggest that targeting macrophage PPAR-γ may be a promising therapeutic option in the future to suppress acute inflammation and simultaneously promote recovery from severe diseases associated with respiratory viral infections.

Innate Lymphoid Cells of the Lung.

Although, as the major organ of gas exchange, the lung is considered a nonlymphoid organ, an interconnected network of lung-resident innate cells, including epithelial cells, dendritic cells, macrophages, and natural killer cells is crucial for its protection. These cells provide defense against a daily assault by airborne bacteria, viruses, and fungi, as well as prevent the development of cancer, allergy, and the outgrowth of commensals. Our understanding of this innate immune environment has recently changed with the discovery of a family of innate lymphoid cells (ILCs): ILC1s, ILC2s, and ILC3s. All lack adaptive antigen receptors but can provide a substantial and rapid source of IFN-γ, IL-5 and IL-13, and IL-17A or IL-22, respectively. Their ability to afford immediate protection to the lung and to influence subsequent adaptive immune responses highlights the importance of understanding ILC-regulated immunity for the design of future therapeutic interventions.

Allergin-1 Immunoreceptor Suppresses House Dust Mite-Induced Allergic Th2 Responses

House dust mite (HDM) allergens are leading causes of allergic asthma characterized by T helper 2 (Th2) responses. The lung-resident CD11b dendritic cells (DCs) play a key role in Th2 cell development in HDM-induced allergic asthma. However, the regulatory mechanism of HDM-induced CD11b DC activation remains incompletely understood. Here, we show that mice deficient in an inhibitory immunoreceptor Allergin-1 exacerbated the HDM-induced airway eosinophilia and serum IgE elevation. HDM directly stimulated lung CD11b DCs via the TLR-4-MyD88 pathway and enhanced prostaglandin E2 (PGE2) production that promoted development of Th2 cells. Allergin-1 suppressed the PGE2 production by inhibiting Syk tyrosine kinase activation through recruitment of SHP-1 in HDM-stimulated CD11b DCs, subsequently leading to negative regulation of Th2 responses. These results suggest that Allergin-1 plays an important role in the regulation of HDM-induced allergic asthma.

A dendritic cell-based systemic vaccine induces long-lived lung-resident memory Th17 cells and ameliorates pulmonary mycosis.

Tissue-resident memory T cells (TRMs) are a novel nonvascular memory T cell subset. Although CD8+ TRMs are well-characterized, CD4+ TRMs-especially lung-resident memory Th17 cells-are still being defined. In this study, we characterized lung-resident memory Th17 cells (lung TRM17) and their role in protection against the highly virulent fungus Cryptococcus gattii. We found that intravenously transferred DCs preferentially migrated to lungs and attracted recipient DCs and led to the induction of long-lived Th17 cells expressing characteristic markers. This population could be clearly discriminated from circulating T cells by intravascular staining and was not depleted by the immunosuppressive agent FTY720. The C. gattii antigen re-stimulation assay revealed that vaccine-induced lung Th17 cells produced IL-17A but not IFNγ. The DC vaccine significantly increased IL-17A production and suppressed fungal burden in the lungs and improved the survival of mice infected with C. gattii. This protective effect was significantly reduced in the IL-17A knockout (KO) mice, but not in the FTY720-treated mice. The protective effect also coincided with the activation of neutrophils and multinucleated giant cells, and these inflammatory responses were suppressed in the vaccinated IL-17A KO mice. Overall, these data demonstrated that the systemic DC vaccine induced lung TRM17, which played a substantial role in anti-fungal immunity.

Abstract B39: Osteosarcoma cells interact with bronchial cells in lung to drive production of prometastatic cytokines

Abstract The survival rate for patients diagnosed with osteosarcoma (OS) drops from 70% to an abysmal 20% when diagnosed with lung metastasis. We have shown that metastatic colonization of lungs by OS cells depends on the production of IL6 and CXCL8 by tumor cells, which seems to increase within the metastatic niche of the lung. Identification of key tumor-host interactions that drive this phenomenon will facilitate the development of novel therapies aimed at prevention of metastases in patients diagnosed with OS. We hypothesized that OS cells interact with lung tissues in ways that establish paracrine signal amplification loops, where IL6 and CXCL8 stimulate lung-resident cells to produce secondary signaling molecules that, in turn, stimulate tumor cell production of IL6 and CXCL8 in a feed-forward mechanism. Coculture experiments identified strong interactions between OS cells and primary cultures of bronchial epithelial cells and lung smooth muscle cells. Exposure of OS cells to conditioned supernatants from the primary cell cultures and vice versa showed that these interactions result from exchange of soluble mediators secreted by each cell type. Proteomic profiling of the resultant supernatants identifies a number of interesting candidate mediators, which might also affect the growth and survival of OS cells within the microenviroment of the lung. These results suggest a mechanism for the establishment of a metastatic niche favorable to OS cells within lung tissues. Citation Format: John Hinckley, Amy Gross, Ryan Roberts. Osteosarcoma cells interact with bronchial cells in lung to drive production of prometastatic cytokines [abstract]. In: Proceedings of the AACR Special Conference: Pediatric Cancer Research: From Basic Science to the Clinic; 2017 Dec 3-6; Atlanta, Georgia. Philadelphia (PA): AACR; Cancer Res 2018;78(19 Suppl):Abstract nr B39.

Lung resident mesenchymal cells isolated from patients with the Bronchiolitis Obliterans Syndrome display a deregulated epigenetic profile

Bronchiolitis Obliterans Syndrome is the major determinant of the graft function loss after lung transplantation, but its pathogenesis is still incompletely understood and currently available therapeutic strategies are poorly effective. A deeper understanding of its pathogenic mechanisms is crucial for the development of new strategies to prevent and treat this devastating complication. In this study, we focused on the mesenchymal stromal cells, recently recognized as BOS key effectors, and our primary aim was to identify their epigenetic determinants, such as histone modifications and non-coding RNA regulation, which could contribute to their differentiation in myofibroblasts. Interestingly, we identified a deregulated expression of histone deacetylases and methyltransferases, and a microRNA-epigenetic regulatory network, which could represent novel targets for anti-fibrotic therapy. We validated our results in vitro, in a cell model of fibrogenesis, confirming the epigenetic involvement in this process and paving the way for a new application for epigenetic drugs.

Lung-resident natural killer cells control pulmonary tumor growth in mice.

Accumulating evidence indicates the importance of natural killer (NK) cells in controlling tumor growth and metastasis. NK cell subsets display diversities in their function and tissue distribution and Mac‐1hi CD27lo NK cells are the predominant population of lung‐resident NK cells. Although the lung is a major organ where primary tumor develops and cancer cells metastasize, there is no clear evidence whether circulating NK cells and/or tissue‐resident NK cells control tumor growth in the lung. In the present study, we examined an antitumor function of lung‐resident NK cells to control pulmonary tumor growth. In an orthotopic lung tumor model, NK cells controlled pulmonary tumor growth, and mature circulating NK cell subsets were increased in tumor‐bearing lungs through a C‐X‐C motif chemokine receptor 3 (CXCR3)‐dependent mechanism. Although such increase in migratory NK cell subsets can be blocked by anti‐CXCR3 treatment, there was no difference in pulmonary tumor growth in anti‐CXCR3‐treated mice compared with control mice. In addition to pulmonary tumor growth, lung‐resident NK cells, but not migratory NK cells, play a dominant role in controlling metastatic growth of cancer cells in lung. These results strongly indicate an importance of lung‐resident NK cells for controlling pulmonary tumor growth.

Abstract 4488: Osteosarcoma cells interact with bronchial cells in lung to drive production of pro-metastatic cytokines

Abstract The survival rate for patients diagnosed with osteosarcoma (OS) drops from 70% to an abysmal 20% when diagnosed with lung metastasis. We have shown that metastatic colonization of lungs by OS cells depends on the production of IL6 and CXCL8 by tumor cells, which seems to increase within the metastatic niche of the lung. Identification of key tumor-host interactions that drive this phenomenon will facilitate the development of novel therapies aimed at prevention of metastases in patients diagnosed with OS. We hypothesized that OS cells interact with lung tissues in ways that establish paracrine signal amplification loops, where IL6 and CXCL8 stimulate lung-resident cells to produce secondary signaling molecules that, in turn, further stimulate tumor cell production of IL6 and CXCL8 in a feed-forward mechanism. Co-culture experiments have identified strong interactions between OS cells and primary cultures of bronchial epithelial cells and lung smooth muscle cells. Exposure of OS cells to conditioned supernatants from the primary cell cultures show that these interactions result from exchange of soluble mediators secreted by each cell type. Proteomic profiling of bronchial cell supernatants following incubation with OS conditioned media identified a number of intriguing candidate mediators, which might facilitate the growth and survival of OS cells within the microenviroment of the lung. Some of those same candidate mediators trigger expression of IL6 and CXCL8 in OS cell cultures. These results suggest a paracrine loop mechanism, where OS cells trigger a response from lung stromal cells that promotes survival and proliferation of the OS cells, establishing a favorable niche for the development of metastasis. Citation Format: John M. Hinckley, Amy Gross, Ryan Roberts. Osteosarcoma cells interact with bronchial cells in lung to drive production of pro-metastatic cytokines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4488.

PO-112 The senescence associated secretory phenotype (SASP)-factor CcL2 fosters vascular dysfunction and endothelial cell loss in radiation-induced lung disease

Introduction Blood vessels are critical targets of the radiation response. Acute vascular damage and dysfunction upon irradiation as well as delayed endothelial cell loss are particularly prominent in the radiation response of normal tissues. However, the mechanisms underlying radiation-induced adverse effects in the vascular compartment remain elusive and no causative radioprotective treatment is available to date. Material and methods Here we investigated the therapeutic potential of Ccl2 signalling inhibition to specifically protect endothelial cells (EC) from injury of radiation-induced acute and late toxicity in lungs after whole thorax irradiation (WTI) using a mouse model of radiation-induced pneumopathy as well as ex vivo cultured human lung tissue. Results and discussions RT-induced vascular dysfunction and associated adverse effects can be efficiently antagonised by inhibition of Ccl2 signalling using either the selective Ccl2 inhibitor bindarit (BIN) or mice deficient for the main Ccl2 receptor CCR2 (KO). BIN-treatment efficiently counteracted the RT-induced expression of Ccl2, normalised endothelial cell (EC) morphology and vascular function and limited lung inflammation and metastasis early after irradiation (acute effects). A similar protection of the vascular compartment was detected by loss of Ccl2 signalling in lungs of CCR2-KO mice. Long-term Ccl2 signalling inhibition also significantly limited EC loss and accompanied fibrosis progression as adverse late effect. With respect to the human situation, we further confirmed that Ccl2 secreted by RT-induced senescent epithelial cells resulted in the activation of normally quiescent but DNA-damaged EC finally leading to EC loss in ex vivo cultured human normal lung tissue. Abrogation of certain aspects of the secretome of irradiated resident lung cells, in particular signalling inhibition of the senescence associated secretory phenotype (SASP)-factor Ccl2 secreted predominantly by RT-induced senescent epithelial cells resulted in protection of the endothelial compartment. Conclusion Radioprotection of the normal tissue via Ccl2 signalling inhibition without simultaneous protection or preferable radiosensitization of tumour tissue might improve local tumour control and survival, because higher doses of radiation could be used.

Impact of Transcriptomics on Our Understanding of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lethal fibrotic lung disease characterized by aberrant remodeling of the lung parenchyma with extensive changes to the phenotypes of all lung resident cells. The introduction of transcriptomics, genome scale profiling of thousands of RNA transcripts, caused a significant inversion in IPF research. Instead of generating hypotheses based on animal models of disease, or biological plausibility, with limited validation in humans, investigators were able to generate hypotheses based on unbiased molecular analysis of human samples and then use animal models of disease to test their hypotheses. In this review, we describe the insights made from transcriptomic analysis of human IPF samples. We describe how transcriptomic studies led to identification of novel genes and pathways involved in the human IPF lung such as: matrix metalloproteinases, WNT pathway, epithelial genes, role of microRNAs among others, as well as conceptual insights such as the involvement of developmental pathways and deep shifts in epithelial and fibroblast phenotypes. The impact of lung and transcriptomic studies on disease classification, endotype discovery, and reproducible biomarkers is also described in detail. Despite these impressive achievements, the impact of transcriptomic studies has been limited because they analyzed bulk tissue and did not address the cellular and spatial heterogeneity of the IPF lung. We discuss new emerging technologies and applications, such as single-cell RNAseq and microenvironment analysis that may address cellular and spatial heterogeneity. We end by making the point that most current tissue collections and resources are not amenable to analysis using the novel technologies. To take advantage of the new opportunities, we need new efforts of sample collections, this time focused on access to all the microenvironments and cells in the IPF lung.

Establishment of an in vivo simulating co-culture assay platform for genotoxicity of multi-walled carbon nanotubes.

Engineered nanomaterials (ENM) are now used in a wide variety of fields, and, thus, their safety should urgently be assessed and secured. It has been suggested that inflammatory responses via the phagocytosis of ENM by macrophages is a key mechanism for their genotoxicity. The present study was conducted to establish a mechanism‐based assay to evaluate the genotoxicity of ENM under conditions simulating an in vivo situation, featuring a co‐culture system of murine lung resident cells (GDL1) and immune cells (RAW264.7). GDL1 were cultured with or without RAW264.7, exposed to a multi‐walled carbon nanotube (MWCNT), and then analyzed for mutagenicity and underlying mechanisms. Mutation frequencies induced in GDL1 by the MWCNT were significantly greater with the co‐existence of RAW264.7 than in its absence. Mutation spectra observed in GDL1 co‐cultured with RAW264.7 were different from those seen in GDL1 cultured alone, but similar to those observed in the lungs of mice exposed to the MWCNT in vivo. Inflammatory cytokines, such as IL‐1β and TNF‐α, were produced from RAW264.7 cells treated with the MWCNT. The generation of reactive oxygen species and the formation of 8‐oxodeoxyguanosine in GDL1 exposed to the MWCNT were greater in the co‐culture conditions than in the single culture conditions. Based on these findings, it is indicated that inflammatory responses are involved in the genotoxicity of MWCNT, and that the presently established, novel in vitro assay featuring a co‐culture system of tissue resident cells with immune cells is suitable to evaluate the genotoxicity of ENM.

Inhibition of Radiation-Induced Ccl2 Signaling Protects Lungs from Vascular Dysfunction and Endothelial Cell Loss.

Aims: Radiation-induced normal tissue toxicity often precludes the application of curative radiation doses. Here we investigated the therapeutic potential of chemokine C-C motif ligand 2 (Ccl2) signaling inhibition to protect normal lung tissue from radiotherapy (RT)-induced injury. Results: RT-induced vascular dysfunction and associated adverse effects can be efficiently antagonized by inhibition of Ccl2 signaling using either the selective Ccl2 inhibitor bindarit (BIN) or mice deficient for the main Ccl2 receptor CCR2 (KO). BIN-treatment efficiently counteracted the RT-induced expression of Ccl2, normalized endothelial cell (EC) morphology and vascular function, and limited lung inflammation and metastasis early after irradiation (acute effects). A similar protection of the vascular compartment was detected by loss of Ccl2 signaling in lungs of CCR2-KO mice. Long-term Ccl2 signaling inhibition also significantly limited EC loss and accompanied fibrosis progression as adverse late effect. With respect to the human situation, we further confirmed that Ccl2 secreted by RT-induced senescent epithelial cells resulted in the activation of normally quiescent but DNA-damaged EC finally leading to EC loss in ex vivo cultured human normal lung tissue. Innovation: Abrogation of certain aspects of the secretome of irradiated resident lung cells, in particular signaling inhibition of the senescence-associated secretory phenotype-factor Ccl2 secreted predominantly by RT-induced senescent epithelial cells, resulted in protection of the endothelial compartment. Conclusions: Radioprotection of the normal tissue via Ccl2 signaling inhibition without simultaneous protection or preferable radiosensitization of tumor tissue might improve local tumor control and survival, because higher doses of radiation could be used.

HVEM Imprints Memory Potential on Effector CD8 T Cells Required for Protective Mucosal Immunity.

Mucosal immunity to reinfection with a highly virulent virus requires the accumulation and persistence of memory CD8 T cells at the site of primary infection. These cells may derive from memory precursor effector cells (MPECs), which are distinct from short-lived effector cells that provide acute protection but are often destined to die. Using respiratory virus infection, we show that herpes virus entry mediator (HVEM; TNFRSF14), a member of the TNF receptor superfamily, provides key signals for MPEC persistence. HVEM-deficient CD8 T cells expanded normally but were skewed away from MPECs with resultant poor development of circulating and lung-resident memory cells. HVEM was selectively expressed on MPECs whereas MPECs deficient in HVEM failed to survive in adoptive transfer recipients. As a consequence, HVEM-deficient recipients failed to afford protection against respiratory reinfection with influenza virus. HVEM therefore represents a critical signal for MPECs and development of protective mucosal CD8 T cell memory.

β2-Adrenoceptor signaling in airway epithelial cells promotes eosinophilic inflammation, mucous metaplasia, and airway contractility

The mostly widely used bronchodilators in asthma therapy are β2-adrenoreceptor (β2AR) agonists, but their chronic use causes paradoxical adverse effects. We have previously determined that β2AR activation is required for expression of the asthma phenotype in mice, but the cell types involved are unknown. We now demonstrate that β2AR signaling in the airway epithelium is sufficient to mediate key features of the asthmatic responses to IL-13 in murine models. Our data show that inhibition of β2AR signaling with an aerosolized antagonist attenuates airway hyperresponsiveness (AHR), eosinophilic inflammation, and mucus-production responses to IL-13, whereas treatment with an aerosolized agonist worsens these phenotypes, suggesting that β2AR signaling on resident lung cells modulates the asthma phenotype. Labeling with a fluorescent β2AR ligand shows the receptors are highly expressed in airway epithelium. In β2AR-/- mice, transgenic expression of β2ARs only in airway epithelium is sufficient to rescue IL-13-induced AHR, inflammation, and mucus production, and transgenic overexpression in WT mice exacerbates these phenotypes. Knockout of β-arrestin-2 (βarr-2-/-) attenuates the asthma phenotype as in β2AR-/- mice. In contrast to eosinophilic inflammation, neutrophilic inflammation was not promoted by β2AR signaling. Together, these results suggest β2ARs on airway epithelial cells promote the asthma phenotype and that the proinflammatory pathway downstream of the β2AR involves βarr-2. These results identify β2AR signaling in the airway epithelium as capable of controlling integrated responses to IL-13 and affecting the function of other cell types such as airway smooth muscle cells.

KRASG12D expression in lung-resident myeloid cells promotes pulmonary LCH-like neoplasm sensitive to statin treatment

AbstractLangerhans cell histiocytosis (LCH) is a rare histiocytic neoplasm associated with somatic mutations in the genes involved in the RAF/MEK/extracellular signal-regulated kinase (ERK) signaling pathway. Recently, oncogenic mutations in NRAS/KRAS, upstream regulators of the RAF/MEK/ERK pathway, have been reported in pulmonary, but not in nonpulmonary, LCH cases, suggesting organ-specific contribution of oncogenic RAS to LCH pathogenesis. Using a mouse model expressing KRASG12D in the lung by nasal delivery of adenoviral Cre recombinase (Cre), here we show that KRASG12D expression in lung-resident myeloid cells induces pulmonary LCH-like neoplasms composed of pathogenic CD11chighF4/80+CD207+ cells. The pathogenic cells were mitotically inactive, but proliferating precursors were detected in primary cultures of lung tissue. These precursors were derived, at least in part, from CD11cdimCD11bintGr1− lung-resident monocytic cells transformed by KRASG12D. In contrast, BRAFV600E expression induced by the same method failed to develop LCH-like neoplasms, suggesting that each oncogene may initiate pulmonary LCH by transforming different types of lung-resident myeloid cells. In vivo treatment of the KRASG12D-induced LCH-like mouse with the cholesterol-lowering drug atorvastatin ameliorated the pathology, implicating statins as potential therapeutics against a subset of pulmonary LCH.

Production of reactive persulfide species in chronic obstructive pulmonary disease

BackgroundOxidative stress is a major aetiological factor driving chronic obstructive pulmonary disease (COPD). Recently recognised as potent antioxidants, reactive persulfide and polysulfide species are biosynthesised by cystathionine β-synthase and cystathionine...