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Electronic cigarette (e-cigarette) vapour is gaining popularity as an alternative to tobacco smoking and can induce acute lung injury. However, the specific role of nicotine in e-cigarette vapour and its long-term effects on the airways, lung parenchyma and vasculature remain unclear. We found thatin vitroexposure to nicotine-containing e-cigarette vapour extract (ECVE) or nicotine-free extract (NF ECVE) induced changes in gene expression of epithelial cells and pulmonary arterial smooth muscle cells (PASMC), but preferentially ECVE caused functional alterations (e.g.decrease of human or mouse PASMC proliferation by 29.3±5.3% or 44.3±8.4%, respectively). Additionally, acute inhalation of nicotine-containing e-cigarette vapour (ECV) but not nicotine-free vapour (NF ECV) increased pulmonary endothelial permeability in isolated lungs. Long-term,in vivoexposure of mice to ECV for 8 months significantly increased the number of inflammatory cells, in particular lymphocytes compared to control and NF ECV in the bronchoalveolar lavage (BAL, ECV: 853.4±150.8, control: 37.0±21.1, NF ECV: 198.6±94.9 cells·mL−1) and in lung tissue (ECV: 25.7±3.3, control: 4.8±1.1, NF ECV: 14.1±2.2 cells·mm−3). BAL-cytokines were predominantly increased by ECV. Moreover, ECV caused significant changes in lung structure and function (e.g.increase in airspace by 17.5±1.4% compared to control), similar to mild tobacco smoke-induced alterations, which also could be detected in the NF ECV group, albeit to a lesser degree. In contrast, the pulmonary vasculature was not significantly affected by ECV or NF ECV. In conclusion, NF ECV components induce cell-type specific effects and mild pulmonary alterations, while inclusion of nicotine induces significant endothelial damage, inflammation and parenchymal alterations.

The ability of vitamin D (VitD) to modulate immune responses in the clinical setting of COVID-19 infection is not well investigated. This study aimed to evaluate the ability of VitD to attenuate inflammatory responses in patients with severe COVID-19.Blood samples and nasopharyngeal swabs were obtained from patients with severe COVID-19 who had been treated (20 patients), or not (25 patients), with VitD, during their stay in the intensive care unit. Western blotting was used to evaluate the expressions of STAT3, JNK and AKT signaling pathways and ELISA was used to measure levels of IL-6, IL-17, and IL-1β in blood of these patients.Reduced levels of STAT3, JNK and AKT pathways and lower levels of proinflammatory cytokines such as IL-6, IL-17, and IL-1β were observed in VitD treated patients (50,000 IU of cholecalciferol weekly for 3 weeks), and in vitro following treatment of poly I:C stimulated PBMCs with VitD (50 nM of calcitriol). Moreover, lower circulatory levels of these proinflammatory cytokines following treatment with VitD were associated with lower serum levels of COVID-19-related severity markers such as D-dimer and C-reactive proteins (P 0.001) which in overall resulted in shorter length of ICU stay for VitD treated compared to untreated patients (18 days for VitD treated vs. 28 days for VitD untreated; P = 0.01).This study reveals that VitD plays immunomodulatory role during COVID-19 infection, which further emphasizes the importance of maintaining a normal level of this vitamin for the prevention of hyperinflammatory conditions associated with COVID-19.

The cytokine interleukin-2 (IL-2) plays a critical role in controlling the immune homeostasis by regulating the proliferation and differentiation of immune cells, especially T cells. IL-2 signaling is mediated via the IL-2 receptor (IL-2R) complex, which consists of the IL-2Rα (CD25), the IL-2Rβ, and the IL-2Rγ. While the latter are required for signal transduction, IL-2Rα controls the ligand-binding affinity of the receptor complex. A soluble form of the IL-2Rα (sIL-2Rα) is found constitutively in human serum, though its levels are increased under various pathophysiological conditions. The sIL-2Rα originates partly from activated T cells through proteolytic cleavage, but neither the responsible proteases nor stimuli that lead to IL-2Rα cleavage are known. Here, we show that the metalloproteases ADAM10 and ADAM17 can cleave the IL-2Rα and generate a soluble ectodomain, which functions as a decoy receptor that inhibits IL-2 signaling in T cells. We demonstrate that ADAM10 is mainly responsible for constitutive shedding of the IL-2Rα, while ADAM17 is involved in IL-2Rα cleavage upon T cell activation. In vivo, we found that mice with a CD4-specific deletion of ADAM10, but not ADAM17, show reduced steady-state sIL-2Rα serum levels. We propose that the identification of proteases involved in sIL-2Rα generation will allow for manipulation of IL-2Rα cleavage, especially as constitutive and induced cleavage of IL-2Rα are executed by different proteases, and thus offer a novel opportunity to alter IL-2 function.

A Disintegrin and Metalloproteinases (ADAM)-10 is a member of a family of membrane-anchored proteinases that regulate a broad range of cellular functions with central roles within the immune system. This has spurred the interest to modulate ADAM activity therapeutically in immunological diseases. CD4 T helper (Th) cells are the key regulators of adaptive immune responses. Their development and function is strongly dependent on Notch, a key ADAM-10 substrate. However, Th cells rely on a variety of additional ADAM-10 substrates regulating their functional activity at multiple levels. The complexity of both, the ADAM substrate expression as well as the functional consequences of ADAM-mediated cleavage of the various substrates complicates the analysis of cell type specific effects. Here we provide an overview on the major ADAM-10 substrates relevant for CD4 T cell biology and discuss the potential effects of ADAM-mediated cleavage exemplified for a selection of important substrates.

Trophic functions for macrophages are emerging as key mediators of developmental processes, including bone, vessel, and mammary gland development. Yolk sac-derived macrophages mature in the distal lung shortly after birth. Myeloid-lineage macrophages are recruited to the lung and are activated under pathological conditions. These pathological conditions include bronchopulmonary dysplasia (BPD), a common complication of preterm birth characterized by stunted lung development, where the formation of alveoli is blocked. No study has addressed causal roles for immune cells in lung alveolarization. We employed antibody-based and transgenic death receptor-based depletion approaches to deplete or prevent lung recruitment of immune cell populations in a hyperoxia-based mouse model of BPD. Neither neutrophils nor exudate macrophages (which might include lung interstitial macrophages) contributed to structural perturbations to the lung that were provoked by hyperoxia; however, cells of the Csf1r-expressing monocyte/macrophage lineage were implicated as causal mediators of stunted lung development. We propose that resident alveolar macrophages differentiate into a population of CD45+ CD11c+ SiglecF+ CD11b+ CD68+ MHCII+ cells, which are activated by hyperoxia, and contribute to disturbances to the structural development of the immature lung. This is the first report that causally implicates immune cells in pathological disturbances to postnatal lung organogenesis. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Influenza A viruses (IAV) can cause lung injury and acute respiratory distress syndrome (ARDS), which is characterized by accumulation of excessive fluid (edema) in the alveolar airspaces and leads to hypoxemia and death if not corrected. Clearance of excess edema fluid is driven mostly by the alveolar epithelial Na,K-ATPase and is crucial for survival of patients with ARDS. We therefore investigated whether IAV infection alters Na,K-ATPase expression and function in alveolar epithelial cells (AECs) and the ability of the lung to clear edema. IAV infection reduced Na,K-ATPase in the plasma membrane of human and murine AECs and in distal lung epithelium of infected mice. Moreover, induced Na,K-ATPase improved alveolar fluid clearance (AFC) in IAV-infected mice. We identified a paracrine cell communication network between infected and noninfected AECs and alveolar macrophages that leads to decreased alveolar epithelial Na,K-ATPase function and plasma membrane abundance and inhibition of AFC. We determined that the IAV-induced reduction of Na,K-ATPase is mediated by a host signaling pathway that involves epithelial type I IFN and an IFN-dependent elevation of macrophage TNF-related apoptosis–inducing ligand (TRAIL). Our data reveal that interruption of this cellular crosstalk improves edema resolution, which is of biologic and clinical importance to patients with IAV-induced lung injury.

Trophic functions for macrophages are emerging as key mediators of developmental processes, including bone, vessel, and mammary gland development. Yolk sac-derived macrophages mature in the distal lung shortly after birth. Myeloid-lineage macrophages are recruited to the lung and are activated under pathological conditions. These pathological conditions include bronchopulmonary dysplasia (BPD), a common complication of preterm birth characterized by stunted lung development, where the formation of alveoli is blocked. No study has addressed causal roles for immune cells in lung alveolarization. We employed antibody-based and transgenic death receptor-based depletion approaches to deplete or prevent lung recruitment of immune cell populations in a hyperoxia-based mouse model of BPD. Neither neutrophils nor exudate macrophages (which might include lung interstitial macrophages) contributed to structural perturbations to the lung that were provoked by hyperoxia; however, cells of the Csf1r-expressing monocyte/macrophage lineage were implicated as causal mediators of stunted lung development. We propose that resident alveolar macrophages differentiate into a population of CD45