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Background: A new approach targeting aeroallergen sensing in the early events of mucosal immunity could have greater benefit. The CSF1‐CSF1R pathway has a critical role in trafficking allergens to regional lymph nodes through activating dendritic cells. Intervention in this pathway could prevent allergen sensitization and subsequent Th2 allergic inflammation. Objective: To examine the therapeutic effectiveness of CSF1 and CSF1R inhibition for blocking the dendritic cell function of sensing aeroallergens. Methods: We adopted a model of chronic asthma induced by a panel of three naturally occurring allergens and novel delivery system of CSF1R inhibitor encapsulated nanoprobe. Results: Selective depletion of CSF1 in airway epithelial cells abolished the production of allergen‐reactive IgE, resulting in prevention of new asthma development as well as reversal of established allergic lung inflammation. CDPL‐GW nanoprobe containing GW2580, a selective CSF1R inhibitor, showed favorable pharmacokinetics for inhalational treatment and intranasal insufflation delivery of CDPL‐GW nanoprobe ameliorated asthma pathologies including allergen‐specific serum IgE production, allergic lung and airway inflammation and airway hyper‐responsiveness (AHR) with minimal pulmonary adverse reaction. Conclusion: The inhibition of the CSF1‐CSF1R signaling pathway effectively suppresses sensitization to aeroallergens and consequent allergic lung inflammation in a murine model of chronic asthma. CSF1R inhibition is a promising new target for the treatment of allergic asthma. [ABSTRACT FROM AUTHOR]

Lipid rafts are subdomains of the cell membrane with distinct protein composition and high concentrations of cholesterol and glycosphingolipids. Raft proteins are thought to mediate diverse cellular processes including signal transduction. However, its cellular mechanisms remain unclear. Caveolin-1 (cav-1, marker protein of caveolae) has been thought as a switchboard between extracellular matrix (ECM) stimuli and intracellular signals. Flotillin-2/reggie-1(Flot-2) is another ubiquitously expressed raft protein which defines non-caveolar raft microdomains (planar raft). Its cellular function is largely uncharacterized. Our novel studies demonstrated that Flot-2, in conjunction with cav-1, played important functions on controlling cell death via regulating Fas pathways. Using Beas2B epithelial cells, we found that in contrast to cav-1, Flot-2 conferred cytoprotection via preventing Fas mediated death-inducing signaling complex (DISC) formation, subsequently suppressed caspase-8 mediated extrinsic apoptosis. Moreover, Flot-2 reduced the mitochondria mediated intrinsic apoptosis by regulating the Bcl-2 family and suppressing cytochrome C release from mitochondria to cytosol. Flot-2 further modulated the common apoptosis pathway and inhibited caspase-3 activation via up-regulating the members in the inhibitor of apoptosis (IAP) family. Last, Flot-2 interacted with cav-1 and limited its expression. Taken together, we found that Flot-2 protected cells from Fas induced apoptosis and counterbalanced the pro-apoptotic effects of cav-1. Thus, Flot-2 played crucial functions in cellular homeostasis and cell survival, suggesting a differential role of individual raft proteins. [ABSTRACT FROM AUTHOR]

Inflammation involves in many cigarette smoke (CS) related diseases including the chronic obstructive pulmonary disease (COPD). Lung epithelial cell released IL-8 plays a crucial role in CS induced lung inflammation. CS and cigarette smoke extracts (CSE) both induce IL-8 secretion and subsequently, IL-8 recruits inflammatory cells into the lung parenchyma. However, the molecular and cellular mechanisms by which CSE triggers IL-8 release remain not completely understood. In this study, we identified a novel extracellular matrix (ECM) molecule, CCN1, which mediated CSE induced IL-8 secretion by lung epithelial cells. We first found that CS and CSE up-regulated CCN1 expression and secretion in lung epithelial cells in vivo and in vitro. CSE up-regulated CCN1 via induction of reactive oxygen spices (ROS) and endoplasmic reticulum (ER) stress. p38 MAPK and JNK activation were also found to mediate the signal pathways in CSE induced CCN1. CCN1 was secreted into ECM via Golgi and membrane channel receptor aquaporin4. After CSE exposure, elevated ECM CCN1 functioned via an autocrine or paracrine manner. Importantly, CCN1 activated Wnt pathway receptor LRP6, subsequently stimulated Wnt pathway component Dvl2 and triggered beta-catenin translocation from cell membrane to cytosol and nucleus. Treatment of Wnt pathway inhibitor suppressed CCN1 induced IL-8 secretion from lung epithelial cells. Taken together, CSE increased CCN1 expression and secretion in lung epithelial cells via induction of ROS and ER stress. Increased ECM CCN1 resulted in augmented IL-8 release through the activation of Wnt pathway. [ABSTRACT FROM AUTHOR]

Lysophosphatidic acid (LPA) species are present in almost all organ systems and play diverse roles through its receptors. Asthma is an airway disease characterized by chronic allergic inflammation where various innate and adaptive immune cells participate in establishing Th2 immune response. Here, we will review the contribution of LPA and its receptors to the functions of immune cells that play a key role in establishing allergic airway inflammation and aggravation of allergic asthma. [ABSTRACT FROM AUTHOR]

Summary Airway epithelial cells (AECs) secrete innate immune cytokines that regulate adaptive immune effector cells. In allergen-sensitized humans and mice, the airway and alveolar microenvironment is enriched with colony stimulating factor-1 (CSF1) in response to allergen exposure. In this study we found that AEC-derived CSF1 had a critical role in the production of allergen reactive-IgE production. Furthermore, spatiotemporally secreted CSF1 regulated the recruitment of alveolar dendritic cells (DCs) and enhanced the migration of conventional DC2s (cDC2s) to the draining lymph node in an interferon regulatory factor 4 (IRF4)-dependent manner. CSF1 selectively upregulated the expression of the chemokine receptor CCR7 on the CSF1R + cDC2, but not the cDC1, population in response to allergen stimuli. Our data describe the functional specification of CSF1-dependent DC subsets that link the innate and adaptive immune responses in T helper 2 (Th2) cell-mediated allergic lung inflammation. [ABSTRACT FROM AUTHOR]

Lung epithelial cell apoptosis is an important feature of hyperoxia-induced lung injury. The death receptor-associated extrinsic pathway and mitochondria-associated intrinsic pathway both mediate the development of lung epithelial cell apoptosis. Despite decades of research, molecular mechanisms of hyperoxia-induced epithelial cell apoptosis remain incompletely understood. Here, we report a novel regulatory paradigm in response to hyperoxia-associated oxidative stress. Hyperoxia markedly upregulated microRNA (miR)-15a/16 levels in lung epithelial cells, bronchoalveolar lavage fluid (BALF) and lung tissue. This effect was mediated by hyperoxia-induced reactive oxygen species. Functionally, miR-15a/16 inhibitors induced caspase-3-mediated lung epithelial cell apoptosis, in the presence of hyperoxia. MiR-15a/16 inhibitors robustly enhanced FADD level and downregulated Bcl-2 expression. Consistently, cleaved caspase-8 and -9 were highly induced in the miR-15a/16-deficient cells, after hyperoxia. Using airway epithelial cell-specific, miR-15a/16−/− mice, we found that Bcl-2 was significantly reduced in lung epithelial cells in vivo after hyperoxia. In contrast, caspase-3, caspase-8 and Bcl-2-associated death promoter (BAD) were highly elevated in the miR-15a/16−/− epithelial cells in vivo. Interestingly, in lung epithelial malignant cells, rather than benign cells, deletion of miR-15a/16 prevented apoptosis. Furthermore, deletion of miR-15a/16 in macrophages also prohibited apoptosis, which is the opposite of what we have found in normal lung epithelial cells. Taken together, our data suggested that miR-15a/16 may exert differential roles in different cell types. MiR-15a/16 deficiency results in lung epithelial cell apoptosis in response to hyperoxia, via modulating both intrinsic and extrinsic apoptosis pathways. [ABSTRACT FROM AUTHOR]

Background TNF-α has been postulated to be a critical mediator contributing to airway inflammation. The purpose of this study was to evaluate the role of TNF-α in the induction of Th17 and Th2 cells related to asthma pathogenesis. Objective To evaluate detailed mechanisms for the modulation of IL-23 by TNF-α in sensitization period. Methods During sensitization period, 10 μg of rat anti-mouse TNF-α mAb was intravenously administrated one hour before the application of OVA and 0.1 μg of LPS. To see the relation between TNF-α and associated effectors cytokine, we replenished TNF-α KO mice with IL-23 during sensitization period. To assess cellular resources, CD11c+ cells isolated from lung tissue after sensitization were treated with anti-TNF-α Ab. Results Treatment of anti-TNF-α mAb during sensitization period significantly reduced airway eosinophilia, serum OVA-specific IgE levels and methacholine AHR compared to isotype Ab. Anti-TNF-α mAb treated mice showed significant reduction in the levels of IL-23 after sensitization in bronchoalveolar lavage fluid (BALF) as well as IL-17A, IL-4 levels in BALF after challenge compared with isotype Ab treated mice. Supplementation of IL-23 in TNF-α KO mice resulted in complete restoration of eosinophilic airway inflammation, AHR, and IL-17A and IL-4 expression in CD4+ T cells. Anti-TNF-α mAb treatment after sensitization significantly diminished the population of IL-23p19-secreting CD11c+ cells in lung. Conclusion TNF-α plays an important role in the development of airway inflammation by enhancing IL-23/Th17 and Th2 immune responses. [ABSTRACT FROM AUTHOR]

Background. Sepsis and sepsis-associated organ failure are devastating conditions. Understanding the detailed cellular/molecular mechanisms involved in sepsis should lead to the identification of novel therapeutic targets.Methods. Cecal ligation and puncture (CLP) was used as a polymicrobial sepsis model in vivo to determine mortality and end-organ damage. Macrophages were adopted as the cellular model in vitro for mechanistic studies.Results. PTRF+/− mice survived longer and suffered less organ damage after CLP. Reductions in nitric oxide (NO) and iNOS biosynthesis were observed in plasma, macrophages, and vital organs in the PTRF+/− mice. Using an acute sepsis model after CLP, we found that iNOS−/− mice had a comparable level of survival as the PTRF+/− mice. Similarly, polymerase I transcript release factor (PTRF) deficiency resulted in decreased iNOS and NO/ROS production in macrophages in vitro. Mechanistically, lipopolysaccharide (LPS) enhanced the co-localization and interaction between PTRF and TLR4 in lipid rafts. Deletion of PTRF blocked formation of the TLR4/Myd88 complex after LPS. Consistent with this, lack of PTRF impaired the TLR4 signaling, as shown by the decreased p-JNK, p-ERK, and p-p38, which are upstream factors involved in iNOS transcription.Conclusion. PTRF is a crucial regulator of TLR4 signaling in the development of sepsis. [ABSTRACT FROM AUTHOR]

Gut microbiota play an important part in the pathogenesis of mucosal inflammation, such as inflammatory bowel disease (IBD). However, owing to the complexity of the gut microbiota, our understanding of the roles of commensal and pathogenic bacteria in the maintenance of immune homeostasis in the gut is evolving only slowly. Here, we evaluated the role of gut microbiota and their secreting extracellular vesicles (EV) in the development of mucosal inflammation in the gut. Experimental IBD model was established by oral application of dextran sulfate sodium (DSS) to C57BL/6 mice. The composition of gut microbiota and bacteria-derived EV in stools was evaluated by metagenome sequencing using bacterial common primer of 16S rDNA. Metagenomics in the IBD mouse model showed that the change in stool EV composition was more drastic, compared to the change of bacterial composition. Oral DSS application decreased the composition of EV from Akkermansia muciniphila and Bacteroides acidifaciens in stools, whereas increased EV from TM7 phylum, especially from species DQ777900_s and AJ400239_s. In vitro pretreatment of A. muciniphila-derived EV ameliorated the production of a pro-inflammatory cytokine IL-6 from colon epithelial cells induced by Escherichia coli EV. Additionally, oral application of A. muciniphila EV also protected DSS-induced IBD phenotypes, such as body weight loss, colon length, and inflammatory cell infiltration of colon wall. Our data provides insight into the role of gut microbiota-derived EV in regulation of intestinal immunity and homeostasis, and A. muciniphila-derived EV have protective effects in the development of DSS-induced colitis. [ABSTRACT FROM AUTHOR]