Ras homolog family member A/Rho-associated protein kinase 1 signaling modulates lineage commitment of mesenchymal stem cells in asthmatic patients through lymphoid enhancer-binding factor 1

Distribution, contribution and regulation of nestin+ cells

BACKGROUND

Nestin is an intermediate filament first reported in neuroepithelial stem cells. Nestin expression could be found in a variety of tissues throughout all systems of the body, especially during tissue development and tissue regeneration processes.

AIM OF REVIEW

This review aimed to summarize and discuss current studies on the distribution, contribution and regulation of nestin+ cells in different systems of the body, to discuss the feasibility ofusing nestin as a marker of multilineage stem/progenitor cells, and better understand the potential roles of nestin+ cells in tissue development, regeneration and pathological processes.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review highlights the potential of nestin as a marker of multilineage stem/progenitor cells, and as a key factor in tissue development and tissue regeneration. The article discussed the current findings, limitations, and potential clinical implications or applications of nestin+ cells. Additionally, it included the relationship of nestin+ cells to other cell populations. We propose potential future research directions to encourage further investigation in the field.

Aberrant activation of TGF-β/ROCK1 enhances stemness during prostatic stromal hyperplasia

Benign prostatic hyperplasia (BPH) is a multifactorial disease in which abnormal growth factor activation and embryonic reawakening are considered important factors. Here we demonstrated that the aberrant activation of transforming growth factor β (TGF-β)/Rho kinase 1 (ROCK1) increased the stemness of BPH tissue by recruiting mesenchymal stem cells (MSCs), indicating the important role of embryonic reawakening in BPH. When TGF-β/ROCK1 is abnormally activated, MSCs are recruited and differentiate into fibroblasts/myofibroblasts, leading to prostate stromal hyperplasia. Further research showed that inhibition of ROCK1 activation suppressed MSC migration and their potential for stromal differentiation. Collectively, our findings suggest that abnormal activation of TGF-β/ROCK1 regulates stem cell lineage specificity, and the small molecule inhibitor GSK269962A could target ROCK1 and may be a potential treatment for BPH.

Discovery of zolinium TSG1180 as a novel agonist of transgelin-2 for treating asthma

Asthma is a complex and heterogeneous respiratory disease that causes serious social and economic burdens. Current drugs such as β2-agonists cannot fully control asthma. Our previous study found that Transgelin-2 is a potential target for treating asthmatic pulmonary resistance. Herein, we discovered a zolinium compound, TSG1180, that showed a strong interaction with Transgelin-2. The equilibrium dissociation constants (KD) of TSG1180 to Transgelin-2 were determined to be 5.363 × 10-6 and 9.81 × 10-6 M by surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). Cellular thermal shift assay (CETSA) results showed that the thermal stability of Transgelin-2 increased after coincubation of TSG1180 with lysates of airway smooth muscle cells (ASMCs). Molecular docking showed that Arg39 may be the key residue for the binding. Then, the SPR result showed that the binding affinity of TSG1180 to Transgelin-2 mutant (R39E) was decreased by 1.69-fold. Real time cell analysis (RTCA) showed that TSG1180 treatment could relax ASMCs by 19 % (P < 0.05). Once Transgelin-2 was inhibited, TSG1180 cannot induce a relaxation effect, suggesting that the relaxation effect was specifically mediated by Transgelin-2. In vivo study showed TSG1180 effectively reduced pulmonary resistance by 64 % in methacholine-induced mice model (P < 0.05). Furthermore, the phosphorylation of Ezrin at T567 was increased by 8.06-fold, the phosphorylation of ROCK at Y722 was reduced by 38 % and the phosphorylation of RhoA at S188 was increased by 52 % after TSG1180 treatment. These results suggested that TSG1180 could be a Transgelin-2 agonist for further optimization and development as an anti-asthma drug.

Navigating the landscape of Rho GTPase signalling system in autoimmunity: A bibliometric analysis spanning over three decades (1990 to 2023)

Ras-homologous (Rho) guanosine triphosphatases (GTPases) are considered a central player in regulating various biological processes, extending to immune regulation. Perturbations in Rho GTPase signalling have been implicated in immune-related dysregulation, contributing to the development of autoimmunity. This study presents a scientometric analysis exploring the interlink between the Rho GTPase signalling system and autoimmunity, while also delving into the trends of past studies. A total of 967 relevant publications from 1990 to 2023 were retrieved from the Web of Science Core Collection database after throrough manual filtering of irrelevant articles. The findings show an upward trajectory in publications related to this field since 2006. Over the past three decades, the United States of America (41.68%) emerged as the primary contributor in advancing our understanding of the association between the Rho GTPase signalling system and autoimmunity. Research in autoimmunity has mainly centered around therapeutic interventions, with an emphasis on studying leukocyte (macrophage) and endothelial remodelling. Interestingly, within the domains of multiple sclerosis and rheumatoid arthritis, the current focus has been directed towards comprehending the role of RhoA, Rac1, and Cdc42. Notably, certain subfamilies of Rho (such as RhoB and RhoC), Rac (including Rac2 and RhoG), Cdc42 (specifically RhoJ), and other atypical Rho GTPases (like RhoE and RhoH) consistently demonstrating compelling link with autoimmunity, but still warrants emphasis in the future study. Hence, strategic manipulation of the Rho signalling system holds immense promise as a pivotal approach to addressing the global challenge of autoimmunity.

Leptin/obR signaling exacerbates obesity-related neutrophilic airway inflammation through inflammatory M1 macrophages

BACKGROUND

Obesity-related asthma is a kind of nonallergic asthma with excessive neutrophil infiltration in the airways. However, the underlying mechanisms have been poorly elucidated. Among the adipokines related to obesity, leptin is related to the inflammatory response. However, little is understood about how leptin acts on the leptin receptor (obR) in neutrophilic airway inflammation in obesity-associated asthma. We explored the inflammatory effects of leptin/obR signaling in an obesity-related neutrophilic airway inflammation mouse model.

METHODS

We established a neutrophilic airway inflammation mouse model using lipopolysaccharide (LPS)/ovalbumin (OVA) sensitization and OVA challenge (LPS + OVA/OVA) in lean, obese, or db/db (obR deficiency) female mice. Histopathological, bronchoalveolar lavage fluid (BALF) inflammatory cell, and lung inflammatory cytokine analyses were used to analyze airway inflammation severity. Western blotting, flow cytometry, reverse transcription-polymerase chain reaction (RT-PCR), and enzyme-linked immunosorbent assay (ELISA) were used to evaluate the underlying mechanisms. In vitro bone marrow-derived macrophage (BMDM) and bone marrow-derived neutrophil experiments were performed.

RESULTS

We found that the serum leptin level was higher in obese than in lean female mice. Compared to LPS/OVA + OVA-treated lean female mice, LPS/OVA + OVA-treated obese female mice had higher peribronchial inflammation levels, neutrophil counts, Th1/Th17-related inflammatory cytokine levels, M1 macrophage polarization levels, and long isoform obR activation, which could be decreased by the obR blockade (Allo-Aca) or obR deficiency, suggesting a critical role of leptin/obR signaling in the pathogenesis of obesity-related neutrophilic airway inflammation in female mice. In in vitro experiments, leptin synergized with LPS/IFN-γ to promote the phosphorylation of the long isoform obR and JNK/STAT3/AKT signaling pathway members to increase M1 macrophage polarization, which was reversed by Allo-Aca. Moreover, leptin/obR-mediated M1 macrophage activity significantly elevated CXCL2 production and neutrophil recruitment by regulating the JNK/STAT3/AKT pathways. In clinical studies, obese patients with asthma had higher serum leptin levels and M1 macrophage polarization levels in induced sputum than non-obese patients with asthma. Serum leptin levels were positively correlated with M1 macrophage polarization levels in patients with asthma.

CONCLUSIONS

Our results demonstrate leptin/obR signaling plays an important role in the pathogenesis of obesity-related neutrophilic airway inflammation in females by promoting M1 macrophage polarization.

SUMOylation of Rho-associated protein kinase 2 induces goblet cell metaplasia in allergic airways

Allergic asthma is characterized by goblet cell metaplasia and subsequent mucus hypersecretion that contribute to the morbidity and mortality of this disease. Here, we explore the potential role and underlying mechanism of protein SUMOylation-mediated goblet cell metaplasia. The components of SUMOylaion machinery are specifically expressed in healthy human bronchial epithelia and robustly upregulated in bronchial epithelia of patients or mouse models with allergic asthma. Intratracheal suppression of SUMOylation by 2-D08 robustly attenuates not only allergen-induced airway inflammation, goblet cell metaplasia, and hyperreactivity, but IL-13-induced goblet cell metaplasia. Phosphoproteomics and biochemical analyses reveal SUMOylation on K1007 activates ROCK2, a master regulator of goblet cell metaplasia, by facilitating its binding to and activation by RhoA, and an E3 ligase PIAS1 is responsible for SUMOylation on K1007. As a result, knockdown of PIAS1 in bronchial epithelia inactivates ROCK2 to attenuate IL-13-induced goblet cell metaplasia, and bronchial epithelial knock-in of ROCK2(K1007R) consistently inactivates ROCK2 to alleviate not only allergen-induced airway inflammation, goblet cell metaplasia, and hyperreactivity, but IL-13-induced goblet cell metaplasia. Together, SUMOylation-mediated ROCK2 activation is an integral component of Rho/ROCK signaling in regulating the pathological conditions of asthma and thus SUMOylation is an additional target for the therapeutic intervention of this disease.

Mechanistic Regulation of Wnt Pathway-Related Progression of Chronic Obstructive Pulmonary Disease Airway Lesions

Chronic obstructive pulmonary disease (COPD) is a chronic disease associated with inflammation and structural changes in the airways and lungs, resulting from a combination of genetic and environmental factors. This interaction highlights significant genes in early life, particularly those involved in lung development, such as the Wnt signaling pathway. The Wnt signaling pathway plays an important role in cell homeostasis, and its abnormal activation can lead to the occurrence of related diseases such as asthma, COPD, and lung cancer. Due to the fact that the Wnt pathway is mechanically sensitive, abnormal activation of the Wnt pathway by mechanical stress contributes to the progression of chronic diseases. But in the context of COPD, it has received little attention. In this review, we aim to summarize the important current evidence on mechanical stress through the Wnt pathway in airway inflammation and structural changes in COPD and to provide potential targets for COPD treatment strategies.

Myocd regulates airway smooth muscle cell remodeling in response to chronic asthmatic injury

Abnormal growth of airway smooth muscle cells is one of the key features in asthmatic airway remodeling, which is associated with asthma severity. The mechanisms underlying inappropriate airway smooth muscle cell growth in asthma remain largely unknown. Myocd has been reported to act as a key transcriptional coactivator in promoting airway-specific smooth muscle development in fetal lungs. Whether Myocd controls airway smooth muscle remodeling in asthma has not been investigated. Mice with lung mesenchyme-specific deletion of Myocd after lung development were generated, and a chronic asthma model was established by sensitizing and challenging the mice with ovalbumin for a prolonged period. Comparison of the asthmatic pathology between the Myocd knockout mice and the wild-type controls revealed that abrogation of Myocd mitigated airway smooth muscle cell hypertrophy and hyperplasia, accompanied by reduced peri-airway inflammation, decreased fibrillar collagen deposition on airway walls, and attenuation of abnormal mucin production in airway epithelial cells. Our study indicates that Myocd is a key transcriptional coactivator involved in asthma airway remodeling. Inhibition of Myocd in asthmatic airways may be an effective approach to breaking the vicious cycle of asthmatic progression, providing a novel strategy in treating severe and persistent asthma. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Integration of transcriptomics and metabolomics reveals pathways involved in MDSC supernatant attenuation of TGF-β1-induced myofibroblastic differentiation of mesenchymal stem cells

Overexposure to transforming growth factor b1 (TGF-β1) induces myofibroblastic differentiation of mesenchymal stem cells (MSCs), which could be attenuated by myeloid-derived suppressor cell (MDSC) supernatant. However, the promyofibroblastic effects of TGF-β1 and the antimyofibroblastic effects of MDSC supernatant in MSCs have not been fully elucidated. To further clarify the latent mechanism and identify underlying therapeutic targets, we used an integrative strategy combining transcriptomics and metabolomics. Bone marrow MSCs were collected 24 h following TGF-β1 and MDSC supernatant treatment for RNA sequencing and untargeted metabolomic analysis. The integrated data were then analyzed to identify significant gene-metabolite correlations. Differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs) were assessed by Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses for exploring the mechanisms of myofibroblastic differentiation of MSCs. The integration of transcriptomic and metabolomic data highlighted significantly coordinated changes in glycolysis/gluconeogenesis and purine metabolism following TGF-β1 and MDSC supernatant treatment. By combining transcriptomic and metabolomic analyses, this study showed that glycolysis/gluconeogenesis and purine metabolism were essential for the myofibroblastic differentiation of MSCs and may serve as promising targets for mechanistic research and clinical practice in the treatment of fibrosis by MDSC supernatant.

Thrombin induces IL-8/CXCL8 expression by DCLK1-dependent RhoA and YAP activation in human lung epithelial cells

Background

Doublecortin-like kinase 1 (DCLK1) has been recognized as a marker of cancer stem cell in several malignancies. Thrombin is crucial in asthma severity as it can promote IL-8/CXCL8 production in lung epithelial cells, which is a potent chemoattractant for neutrophils. However, the pathologic role of DCLK1 in asthma and its involvement in thrombin-stimulated IL-8/CXCL8 expression remain unknown.

Methods

IL-8/CXCL8, thrombin, and DCLK1 expression were observed in the lung tissues of severe asthma patients and ovalbumin (OVA)-induced asthmatic mice model. A549 and BEAS-2B cells were either pretreated with inhibitors or small interfering RNAs (siRNAs) before being treated with thrombin. IL-8/CXCL8 expression and the molecules involved in signaling pathway were performed using ELISA, luciferase activity assay, Western blot, or ChIP assay.

Results

IL-8/CXCL8, thrombin, and DCLK1 were overexpressed in the lung tissues of severe asthma patients and ovalbumin (OVA)-induced asthmatic mice model. Our in vitro study found that DCLK siRNA or LRKK2-IN-1 (DCLK1 inhibitor) attenuated IL-8/CXCL8 release after thrombin induction in A549 and BEAS-2B cells. Thrombin activated DCLK1, RhoA, and YAP in a time-dependent manner, in which DCLK1 siRNA inhibited RhoA and YAP activation. YAP was dephosphorylated on the Ser127 site after thrombin stimulation, resulting in YAP translocation to the nucleus from the cytosol. DCLK1, RhoA and YAP activation following thrombin stimulation were inhibited by U0126 (ERK inhibitor). Moreover, DCLK1 and YAP siRNA inhibited κB-luciferase activity. Thrombin stimulated the recruitment of YAP and p65 to the NF-κB site of the IL-8/CXCL8 promoter and was inhibited by DCLK1 siRNA.

Conclusions

Thrombin activates the DCLK1/RhoA signaling pathway, which promotes YAP activation and translocation to the nucleus from the cytosol, resulting in YAP/p65 formation, and binding to the NF-κB site, which enhances IL-8/CXCL8 expression. DCLK1 might be essential in thrombin-stimulated IL-8/CXCL8 expression in asthmatic lungs and indicates a potential therapeutic strategy for severe asthma treatment.

Advances in the pharmacological treatment of hepatic alveolar echinococcosis: From laboratory to clinic

Hepatic alveolar echinococcosis (HAE) is a zoonotic parasitic disease caused by the larvae of Echinococcus multilocularis. Because of its characteristics of diffuse infiltration and growth similar to tumors, the disability rate and mortality rate are high among patients. Although surgery (including hepatectomy, liver transplantation, and autologous liver transplantation) is the first choice for the treatment of hepatic alveolar echinococcosis in clinic, drug treatment still plays an important and irreplaceable role in patients with end-stage echinococcosis, including patients with multiple organ metastasis, patients with inferior vena cava invasion, or patients with surgical contraindications, etc. However, Albendazole is the only recommended clinical drug which could exhibit a parasitostatic rather than a parasitocidal effect. Novel drugs are needed but few investment was made in the field because the rarity of the cases. Drug repurposing might be a solution. In this review, FDA-approved drugs that have a potential curative effect on hepatic alveolar echinococcosis in animal models are summarized. Further, nano drug delivery systems boosting the therapeutic effect on hepatic alveolar echinococcosis are also reviewed. Taken together, these might contribute to the development of novel strategy for advanced hepatic alveolar echinococcosis.

Protective effect of oxyberberine against acute lung injury in mice via inhibiting RhoA/ROCK signaling pathway

Acute lung injury (ALI), hallmarked with alveolar epithelial barrier impairment and pulmonary edema induced by acute inflammation, presents a severe health burden to the public, due to the limited available interventions. Oxyberberine (OBB), having improved anti-inflammatory activity and safety, is a representative component with various activities derived from berberine, whereas its role against ALI with alveolar epithelial barrier injury remains uncertain. To investigate the influence and underlying mechanisms of OBB on ALI, we induced acute inflammation in mice and A549 cells by using lipopolysaccharide (LPS). Changes in alveolar permeability were assessed by analyzing lung histopathology, measuring the dry/wet weight ratio of the lungs, and altering proinflammatory cytokines and neutrophils levels in the bronchoalveolar lavage fluid (BALF). Parameters of pulmonary permeability were assessed through ELISA, western blotting, quantitative real-time PCR, and immunofluorescence analysis. U46619, the agonist of RhoA/ROCK, was employed to further investigate the mechanism of OBB on ALI. Unexpectedly, we found OBB mitigated lung impairment, pulmonary edema, inflammatory reactions in BALF and lung tissue, reduction in ZO-1, and addition of connexin-43. Besides, OBB markedly reduced the expression of RhoA in association with its downstream factors, which are linked to the intercellular junctions and permeability both in vivo and in vitro. Nevertheless, U46619 abolished the benefits obtained from OBB in A549 cells. In conclusion, these outcomes indicated that OBB exerted RhoA/ROCK inhibitor-like effect to moderate alveolar epithelial barrier impairment and permeability, ultimately preventing ALI progression.

Echinococcus multilocularis drives the polarization of macrophages by regulating the RhoA-MAPK signaling pathway and thus affects liver fibrosis

Echinococcus multilocularis is a small parasite that causes alveolar echinococcosis. It primarily induces liver disorder, such as liver fibrosis and even liver cancer, which severely endangers human lives. This study aims to explore the efficacy of Echinococcus multilocularis soluble antigen in preventing and alleviating alveolar echinococcosis-induced liver fibrosis and determine the underlying mechanism. We first identified the optimal dose and time of Echinococcus multilocularis soluble antigen. The protein levels of key genes in the RhoA-MAPK signaling pathway were remarkably upregulated in RAW264.7 and Ana-1 cells induced with 80 μg/mL Echinococcus multilocularis soluble antigen for 8 h. Interestingly, the upregulated expression levels were remarkably reversed by the RhoA, JNK, ERK, or p38 inhibitor, confirming the significance of the RhoA-MAPK signaling pathway. In addition, the relative contents of M2 polarization markers IL-10 and Arg-1 in macrophages induced with 80 μg/mL Echinococcus multilocularis soluble antigen for 8 h increased, whereas those of M1 polarization markers IL-12 and NOS-2 decreased. Mouse hepatic stellate cells were the key components of the hepatocellular carcinoma tumor microenvironment. Hepatic stellate cells were activated by Echinococcus multilocularis soluble antigen and transformed into the morphology of myofibroblasts in response to liver disorders. By detecting the marker of myofibroblast formation, RhoA inhibitor remarkably reduced the positive expression of α-SMA in mouse hepatic stellate cells induced with Echinococcus multilocularis soluble antigen. Therefore, Echinococcus multilocularis soluble antigen remarkably activated the RhoA-MAPK pathways in macrophages, further inducing the polarization of macrophages and ultimately causing liver fibrosis. Hypothesis: We hypothesize that infection with Echinococcus multilocularis activates the RhoA-MAPK signaling pathway and subsequently induces macrophage polarization to promote hepatic stellate cells activation leading to liver fibrosis. Aims: To investigate the mechanism by which soluble antigen of Echinococcus multilocularis affects liver fibrosis through the RhoA-MAPK pathway driving polarization of macrophages. Goals: To identify new pathways of intervention and drug targets for the regulation of macrophage polarity phenotype switching and the attenuation or inhibition of the development and treatment of liver fibrosis caused by Echinococcus multilocularis infection.

Stem cell differentiation with consistent lineage commitment induced by a flash of ultrafast-laser activation in vitro and in vivo

Recent technological advancements on stem cell differentiation induction have been making great progress in stem cell research, regenerative medicine, and therapeutic applications. However, the risk of off-target differentiation limits the wide application of stem cell therapy strategies. Here, we report a non-invasive all-optical strategy to induce stem cell differentiation in vitro and in vivo that activates individual target stem cells in situ by delivering a transient 100-ms irradiation of a tightly focused femtosecond laser to a submicron cytoplasmic region of primary adipose-derived stem cells (ADSCs). The ADSCs differentiate to osteoblasts with stable lineage commitment that cannot further transdifferentiate because of simultaneous initiation of multiple signaling pathways through specific Ca²⁺ kinetic patterns. This method can work in vivo to direct mouse cerebellar granule neuron progenitors to granule neurons in intact mouse cerebellums through the skull. Hence, this optical method without any genetic manipulations or exogenous biomaterials holds promising potential in biomedical research and cell-based therapies.

Monocytic Myeloid-Derived Suppressor Cells Inhibit Myofibroblastic Differentiation in Mesenchymal Stem Cells Through IL-15 Secretion

Background: Accumulating evidence indicates that mesenchymal stem cells (MSCs) are precursors of myofibroblasts, which play a vital role in renal fibrosis. The close interaction between MSCs and other immune cells regulates the development of multiple fibrosis-related diseases. However, the effect of myeloid-derived suppressor cells (MDSCs) on MSCs remains unexplored. Here, we investigated the effect of MDSCs on the myofibroblastic differentiation of MSCs.

Methods: MSCs were induced to undergo myofibroblastic differentiation with transforming growth factor beta 1 (TGF-β1). M-MDSCs and G-MDSCs were sorted by flow cytometry. Supernatants derived from MDSCs were administered to cultured bone marrow MSCs (BM-MSCs) undergoing TGF-β1-induced myofibroblastic differentiation. Myofibroblastic differentiation was evaluated by immunostaining. The expression of fibrosis-related genes was determined by quantitative PCR and western blot analysis. In vitro, M-MDSC supernatant or M-MDSC supernatant with interleukin (IL)-15 mAbs was administered following unilateral renal ischemia-reperfusion injury (IRI) to observe the myofibroblast differentiation of renal resident MSCs (RRMSCs) in a murine model.

Results: Myofibroblastic differentiation of MSCs was hindered when the cells were treated with MDSC-derived supernatants, especially that from M-MDSCs. The inhibitory effect of M-MDSC supernatant on the myofibroblastic differentiation of MSCs was partially mediated by IL-15-Ras-Erk1/2-Smad2/3 signaling. Treatment with M-MDSC supernatant ameliorated renal fibrosis and myofibroblastic differentiation in RRMSCs through IL-15. Additionally, M-MDSC supernatant increased M-MDSC infiltration in the kidney in a mouse IRI model. M-MDSC supernatant downregulated the adhesion and migration marker CD44 on the cell membrane of MSCs via IL-15.

Conclusion: M-MDSC-derived supernatant inhibited the TGF-β1-induced myofibroblastic differentiation of MSCs through IL-15. Our findings shed new light on the effect of MDSCs on myofibroblastic differentiation and adhesion of MSCs, which might provide a new perspective in the development of treatment strategies for renal fibrosis.

TH17 cells and corticosteroid insensitivity in severe asthma

Asthma is classically described as having either a type 2 (T2) eosinophilic phenotype or a non-T2 neutrophilic phenotype. T2 asthma usually responds to classical bronchodilation therapy and corticosteroid treatment. Non-T2 neutrophilic asthma is often more severe. Patients with non-T2 asthma or late-onset T2 asthma show poor response to the currently available anti-inflammatory therapies. These therapeutic failures result in increased morbidity and cost associated with asthma and pose a major health care problem. Recent evidence suggests that some non-T2 asthma is associated with elevated T_H17 cell immune responses. T_H17 cells producing Il-17A and IL-17F are involved in the neutrophilic inflammation and airway remodeling processes in severe asthma and have been suggested to contribute to the development of subsets of corticosteroid-insensitive asthma. This review explores the pathologic role of T_H17 cells in corticosteroid insensitivity of severe asthma and potential targets to treat this endotype of asthma.

Rho Kinases in Embryonic Development and Stem Cell Research

The Rho-associated coiled-coil containing kinases (ROCKs or Rho kinases) belong to the AGC (PKA/PKG/PKC) family of serine/threonine kinases and are major downstream effectors of small GTPase RhoA, a key regulator of actin-cytoskeleton reorganization. The ROCK family contains two members, ROCK1 and ROCK2, which share 65% overall identity and 92% identity in kinase domain. ROCK1 and ROCK2 were assumed to be functionally redundant, based largely on their major common activators, their high degree kinase domain homology, and study results from overexpression with kinase constructs or chemical inhibitors. ROCK signaling research has expanded to all areas of biology and medicine since its discovery in 1996. The rapid advance is befitting ROCK’s versatile functions in modulating various cell behavior, such as contraction, adhesion, migration, proliferation, polarity, cytokinesis, and differentiation. The rapid advance is noticeably driven by an extensive linking with clinical medicine, including cardiovascular abnormalities, aberrant immune responsive, and cancer development and metastasis. The rapid advance during the past decade is further powered by novel biotechnologies including CRISPR-Cas and single cell omics. Current consensus, derived mainly from gene targeting and RNA interference approaches, is that the two ROCK isoforms have overlapping and distinct cellular, physiological and pathophysiology roles. In this review, we present an overview of the milestone discoveries in ROCK research. We then focus on the current understanding of ROCK signaling in embryonic development, current research status using knockout and knockin mouse models, and stem cell research.

Nestin-Expressing Cells in the Lung: The Bad and the Good Parts

Nestin is a member of the intermediate filament family, which is expressed in a variety of stem or progenitor cells as well as in several types of malignancies. Nestin might be involved in tissue homeostasis or repair, but its expression has also been associated with processes that lead to a poor prognosis in various types of cancer. In this article, we review the literature related to the effect of nestin expression in the lung. According to most of the reports in the literature, nestin expression in lung cancer leads to an aggressive phenotype and resistance to chemotherapy as well as radiation treatments due to the upregulation of phenomena such as cell proliferation, angiogenesis, and metastasis. Furthermore, nestin may be involved in the pathogenesis of some non-cancer-related lung diseases. On the other hand, evidence also indicates that nestin-positive cells may have a role in lung homeostasis and be capable of generating various types of lung tissues. More research is necessary to establish the true value of nestin expression as a prognostic factor and therapeutic target in lung cancer in addition to its usefulness in therapeutic approaches for pulmonary diseases.

Epithelial Aryl Hydrocarbon Receptor Protects From Mucus Production by Inhibiting ROS-Triggered NLRP3 Inflammasome in Asthma

Background

Despite long-standing recognition in the significance of mucus overproduction in asthma, its etiology remains poorly understood. Muc5ac is a secretory mucin that has been associated with reduced pulmonary function and asthma exacerbations.

Objectives

We sought to investigate the immunological pathway that controls Muc5ac expression and allergic airway inflammation in asthma.

Methods

Cockroach allergen-induced Muc5ac expression and aryl hydrocarbon receptor (AhR) signaling activation was examined in the human bronchial epithelial cells (HBECs) and mouse model of asthma. AhR regulation of Muc5ac expression, mitochondrial ROS (Mito-ROS) generation, and NLRP3 inflammasome was determined by AhR knockdown, the antagonist CH223191, and AhR-/- mice. The role of NLRP3 inflammasome in Muc5ac expression and airway inflammation was also investigated.

Results

Cockroach allergen induced Muc5ac overexpression in HBECs and airways of asthma mouse model. Increased expression of AhR and its downstream genes CYP1A1 and CYP1B1 was also observed. Mice with AhR deletion showed increased allergic airway inflammation and MUC5AC expression. Moreover, cockroach allergen induced epithelial NLRP3 inflammasome activation (e.g., NLRP3, Caspase-1, and IL-1β), which was enhanced by AhR knockdown or the antagonist CH223191. Furthermore, AhR deletion in HBECs led to enhanced ROS generation, particularly Mito-ROS, and inhibition of ROS or Mito-ROS subsequently suppressed the inflammasome activation. Importantly, inhibition of the inflammasome with MCC950, a NLRP3-specifc inhibitor, attenuated allergic airway inflammation and Muc5ac expression. IL-1β generated by the activated inflammasomes mediated cockroach allergen-induced Muc5ac expression in HBECs.

Conclusions

These results reveal a previously unidentified functional axis of AhR-ROS-NLRP3 inflammasome in regulating Muc5ac expression and airway inflammation.

Phactr1 negatively regulates bone mass by inhibiting osteogenesis and promoting adipogenesis of BMSCs via RhoA/ROCK2

The imbalance between osteogenic and adipogenic differentiation of Bone marrow-derived mesenchymal stem cells (BMSCs) is involved in the occurrence and development of osteoporosis (OP). Previous studies have indicated the potential of phosphatase and actin regulator 1 (Phactr1) in regulating osteogenic and adipogenic differentiation of BMSCs. The present study aims to investigate the function and mechanism of Phactr1 in regulating osteogenic and adipogenic differentiation of BMSCs. Herein, the expression of Phactr1 in bone and adipose tissue of OP rats was determined by immunohistochemical. BMSCs were subjected to osteogenic and adipogenic differentiation, and transfected with Phactr1 overexpression lentivirus, small interference RNA (siRNA) and KD025 (selective ROCK2 inhibitor). The relationship between Phactr1 and ROCK2 was detected by Co-IP experiment. The expression of Phactr1, Runx2, C/EBPα, RhoA and ROCK2 was detected by Western blot. Calcium nodule and lipid droplets were determined by alizarin red and Oil red O staining. Interestingly, Phactr1 increased in both bone and adipose tissue of OP rats. During osteogenic differentiation, Phactr1 decreased and active RhoA, ROCK2 increased, while overexpression Phactr1 inhibits the increase of Runx2. Phactr1 increased and active RhoA decreased, ROCK2 did not changed during adipogenic differentiation. While, Knockdown Phactr1 inhibits the increase of C/EBPα. Phactr1 and ROCK2 were combined in osteogenic differentiation, but not in adipogenic differentiation. By using KD025, the decrease of Phactr1 and increase of Runx2 were inhibited respectively in osteogenic differentiation. Meanwhile, when ROCK2 was inhibited, Phactr1, C/EBPα were significantly increased in adipogenic differentiation. These findings indicated that Phactr1 negatively regulates bone mass by inhibiting osteogenesis and promoting adipogenesis of BMSCs by activating RhoA/ROCK2.

Nestin promotes pulmonary fibrosis via facilitating recycling of TGF-β receptor I

Background

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease that is characterised by aberrant proliferation of activated myofibroblasts and pathological remodelling of the extracellular matrix. Previous studies have revealed that the intermediate filament protein nestin plays key roles in tissue regeneration and wound healing in different organs. Whether nestin plays a critical role in the pathogenesis of IPF needs to be clarified.

Methods

Nestin expression in lung tissues from bleomycin-treated mice and IPF patients was determined. Transfection with nestin short hairpin RNA vectors in vitro that regulated transcription growth factor (TGF)-β/Smad signalling was conducted. Biotinylation assays to observe plasma membrane TβRI, TβRI endocytosis and TβRI recycling after nestin knockdown were performed. Adeno-associated virus serotype (AAV)6-mediated nestin knockdown was assessed in vivo.

Results

We found that nestin expression was increased in a murine pulmonary fibrosis model and IPF patients, and that the upregulated protein primarily localised in lung α-smooth muscle actin-positive myofibroblasts. Mechanistically, we determined that nestin knockdown inhibited TGF-β signalling by suppressing recycling of TβRI to the cell surface and that Rab11 was required for the ability of nestin to promote TβRI recycling. In vivo, we found that intratracheal administration of AAV6-mediated nestin knockdown significantly alleviated pulmonary fibrosis in multiple experimental mice models.

Conclusion

Our findings reveal a pro-fibrotic function of nestin partially through facilitating Rab11-dependent recycling of TβRI and shed new light on pulmonary fibrosis treatment.

Nestin regulates the vesicular trafficking system by promoting Rab11-dependent recycling of TβRI and thereby contributes to the progression of pulmonary fibrosis. Precise targeting of nestin may represent a potential therapeutic strategy for IPF.https://bit.ly/3zO75c3

The Rho kinase (ROCK) inhibitor Y-27632 reduces the β2-adrenoceptor density but enhance cAMP formation in primary equine bronchial epithelial cells

The present study addresses the effect of the Rho-kinase (ROCK) inhibitor Y-27632 on the β2-adrenoceptor density and β-agonist-stimulated intracellular second messenger cAMP formation in primary equine bronchial epithelial cells (EBEC). Y-27632 significantly decreased the β2-adrenoceptor number (Bmax) without markedly affecting the receptor affinity (dissociation constant, KD) to the radioligand [125I]-iodocyanopindolol (ICYP). In contrast, Y-27632 augmented the β-agonist-stimulated intracellular cAMP production. Herein, Y-27632 markedly increased the maximal cAMP responses (Emax) (isoproterenol > epinephrine > norepinephrine) but did not shift the β-agonist concentration-effect curves to the left. The β2-selective antagonist ICI 118.551 and the β1/β2-antagonsit propranolol but not the β1-selctive antagonist CGP 20712A reversed the isoproterenol-induced cAMP formation equally in Y-27632-treated and control EBEC, suggesting the effect was merely related to the β2-subtype. These results show that Y-27632 differentially regulates the receptor density and function. Thus, these findings provide the first evidence that the functional interaction of the β2-adrenoceptor and Rho-kinase (ROCK) signaling pathways decreases the receptor expression but enhances receptor downstream cAMP formation. This differential regulation of the receptor density and function by Y-27632 should be further reconsidered with regard to the beneficial effect of the drug in asthma therapy.

Type II alveolar epithelial cell-specific loss of RhoA exacerbates allergic airway inflammation through SLC26A4

The small GTPase RhoA and its downstream effectors are critical regulators in the pathophysiological processes of asthma. The underlying mechanism, however, remains undetermined. Here, we generated an asthma mouse model with RhoA–conditional KO mice (Sftpc-cre;RhoA^fl/fl) in type II alveolar epithelial cells (AT2) and demonstrated that AT2 cell–specific deletion of RhoA leads to exacerbation of allergen-induced airway hyperresponsiveness and airway inflammation with elevated Th2 cytokines in bronchoalveolar lavage fluid (BALF). Notably, Sftpc-cre;RhoA^fl/fl mice showed a significant reduction in Tgf-β1 levels in BALF and lung tissues, and administration of recombinant Tgf-β1 to the mice rescued Tgf-β1 and alleviated the increased allergic airway inflammation observed in Sftpc-cre;RhoA^fl/fl mice. Using RNA sequencing technology, we identified Slc26a4 (pendrin), a transmembrane anion exchange, as the most upregulated gene in RhoA-deficient AT2 cells. The upregulation of SLC26A4 was further confirmed in AT2 cells of asthmatic patients and mouse models and in human airway epithelial cells expressing dominant-negative RHOA (RHOA-N19). SLA26A4 was also elevated in serum from asthmatic patients and negatively associated with the percentage of forced expiratory volume in 1 second (FEV₁%). Furthermore, SLC26A4 inhibition promoted epithelial TGF-β1 release and attenuated allergic airway inflammation. Our study reveals a RhoA/SLC26A4 axis in AT2 cells that functions as a protective mechanism against allergic airway inflammation.

Rho/ROCK-MYOCD in regulating airway smooth muscle growth and remodeling

Abnormal airway remodeling is a common pathological change seen in chronic respiratory diseases. Altered proliferation and differentiation of airway smooth muscle cells (ASMCs) are the major components of airway remodeling, and the resultant structural abnormalities are difficult to restore. Understanding of airway smooth muscle regulation is urgently needed to identify potential intervention targets. MYOCD (or myocardin) and myocardin-related transcription factors (MRTFs) are key cotranscription factors in muscle growth, which have not been extensively investigated in airway smooth muscle cells. In addition, the RhoA/ROCK signaling pathway is known to play an important role in airway remodeling partly through regulating the proliferation and differentiation of ASMCs, which may be connected with MYOCD/MRTF cotranscription factors [Kumawat et al. (Am J Physiol Lung Cell Mol Physiol 311: L529-L537, 2016); Lagna et al. (J Biol Chem 282: 37244-37255, 2007)]. This review focuses on this newly recognized and potentially important RhoA/ROCK-MYOCD/MRTFs pathway in controlling airway smooth muscle growth and remodeling.

Benzo(a)pyrene Enhanced Dermatophagoides Group 1 (Der f 1)-Induced TGFβ1 Signaling Activation Through the Aryl Hydrocarbon Receptor-RhoA Axis in Asthma

We have previously demonstrated that benzo(a)pyrene (BaP) co-exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1-induced airway inflammation. The underlying mechanism, however, remains undetermined. Here we investigated the molecular mechanisms underlying the potentiation of BaP exposure on Der f 1-induced airway inflammation in asthma. We found that BaP co-exposure potentiated Der f 1-induced TGFβ1 secretion and signaling activation in human bronchial epithelial cells (HBECs) and the airways of asthma mouse model. Moreover, BaP exposure alone or co-exposure with Der f 1-induced aryl hydrocarbon receptor (AhR) activity was determined by using an AhR-dioxin-responsive element reporter plasmid. The BaP and Der f 1 co-exposure-induced TGFβ1 expression and signaling activation were attenuated by either AhR antagonist CH223191 or AhR knockdown in HBECs. Furthermore, AhR knockdown led to the reduction of BaP and Der f 1 co-exposure-induced active RhoA. Inhibition of RhoA signaling with fasudil, a RhoA/ROCK inhibitor, suppressed BaP and Der f 1 co-exposure-induced TGFβ1 expression and signaling activation. This was further confirmed in HBECs expressing constitutively active RhoA (RhoA-L63) or dominant-negative RhoA (RhoA-N19). Luciferase reporter assays showed prominently increased promoter activities for the AhR binding sites in the promoter region of RhoA. Inhibition of RhoA suppressed BaP and Der f 1 co-exposure-induced airway hyper-responsiveness, Th2-associated airway inflammation, and TGFβ1 signaling activation in asthma. Our studies reveal a previously unidentified functional axis of AhR–RhoA in regulating TGFβ1 expression and signaling activation, representing a potential therapeutic target for allergic asthma.

CaMKII oxidation regulates cockroach allergen-induced mitophagy in asthma

BACKGROUND

Autophagy plays an important role in causing inflammatory responses initiated by environmental pollutants and respiratory tract infection.

OBJECTIVE

We sought to investigate the role of cockroach allergen-induced excessive activation of autophagy in allergic airway inflammation and its underlying molecular mechanisms.

METHODS

Environmental allergen-induced autophagy was investigated in the primary human bronchial epithelial cells (HBECs) and lung tissues of asthmatic mouse model and patients. The role of autophagy in asthma development was examined by using autophagy inhibitor 3-methyladenine in an asthma mouse model. Furthermore, the involvements of reactive oxygen species (ROS) and oxidized Ca2+/calmodulin-dependent protein kinase II (ox-CaMKII) signaling in regulating autophagy during asthma were examined in allergen-treated HBECs and mouse model.

RESULTS

Cockroach allergen activated autophagy in HBECs and in the lung tissues from asthmatic patients and mice. Autophagy inhibitor 3-methyladenine significantly attenuated airway hyperresponsiveness, TH2-associated lung inflammation, and ROS generation. Mechanistically, we demonstrated a pathological feedforward circuit between cockroach allergen-induced ROS and autophagy that is mediated through CaMKII oxidation. Furthermore, transgenic mice with ROS-resistant CaMKII MM-VVδ showed attenuation of TH2-associated lung inflammation and autophagy. Mitochondrial ox-CaMKII inhibition induced by adenovirus carrying mitochondrial-targeted inhibitor peptide CaMKIIN suppresses cockroach allergen-induced autophagy, mitochondrial dysfunction, mitophagy, and cytokine production in HBECs. Finally, mitochondrial CaMKII inhibition suppressed the expression of one of the key ubiquitin-binding autophagy receptors, optineurin, and its recruitment to fragmented mitochondria. Optineurin knockdown inhibited cockroach allergy-induced mitophagy.

CONCLUSIONS

Our data suggest a previously uncovered axis of allergen-ROS-ox-CaMKII-mitophagy in the development of allergic airway inflammation and asthma.

Twist1 sustains the apoptosis resistance in eosinophils in nasal mucosa of allergic rhinitis

Eosinophils (Eos) are the canonical effector cells in allergic rhinitis (AR) and many inflammatory diseases. The mechanism of eosinophilia occurring in the lesion sites is not fully understood yet. Twist1 protein (Twist, in short) is an apoptosis inhibitor that also has immune regulatory functions. This study aims to investigate the role of Twist in the pathogenesis of eosinophilia in AR. In this study, surgically removed human nasal mucosal samples were obtained from patients with chronic sinusitis and nasal polyps with AR (the AR group) or without AR (the nAR group). Eos were isolated from the samples by flow cytometry. We found that abundant Eos were obtained from the surgically removed nasal mucosa tissues of both nAR and AR groups. Significantly higher Ras activation was detected in AR Eos than that in nAR Eos. Ras activation was associated with the apoptosis resistance in AR Eos. The Twist (an apoptosis inhibitor) expression was higher in AR Eos, which was positively correlated with the Ras activation status. The sensitization to IgG induced Twist expression in Eos, in which Ras activated the MAPK-HIF-1α pathway, the latter promoted the Twist gene transcription. Twist bound Rac GTPase activating protein-1 to sustain the Ras activation in Eos. Ras activation sustained the apoptosis resistance in Eos. In conclusion, high Ras activation was detected in the AR nasal mucosal tissue-isolated Eos. IgG-sensitization induced Ras activation and Twist expression in Eos, that conferred Eos the apoptosis resistance.

A narrative review of research advances in mesenchymal stem cell therapy for asthma

Asthma is a chronic inflammatory disease of the airways that involves multiple cells, including inflammatory cells, structural cells, and cellular components. Glucocorticoids and beta-receptor agonists are still the first choices for asthma treatment. However, the asthma symptoms may still be poorly controlled in some patients after an optimal treatment. Mesenchymal stem cells (MSCs) are characterized by the potential for multi-directional differentiation and can exert immunomodulatory and anti-inflammatory effects. Its role in treating asthma has increasingly been recognized in recent years. In this review article, we sought to summarize the recent advances in the therapeutic effects of MSCs on several types of asthma and explain the relevant mechanisms. Articles on asthma treatment with MSCs as of January 2020 were searched in PubMed, Google Scholar, and Web of Science databases. It was found that MSCs have therapeutic effects on allergic asthma, non-allergic asthma and occupational asthma; gene-modified or pretreated MSCs improves the therapeutic effects of MSCs in asthma; MSC-derived conditioned medium or extracellular vesicles possess the considerable curative effect as MSC on asthma; and MSCs exert their therapeutic effects on asthma by restoring Th1/Th2 balance, reversing Th17/Tregs imbalance, inhibiting DC maturation, and promoting the switch of M1 to M2 and repairing epithelial injury. Thus, MSCs may be a promising treatment for asthma.

RhoA/Rho-kinases in asthma: from pathogenesis to therapeutic targets

Asthma is a chronic and heterogeneous disease characterised by airway inflammation and intermittent airway narrowing. The key obstacle in the prevention and treatment of asthma has been our incomplete understanding of its aetiology and biological mechanisms. The ras homolog family member A (RhoA) of the Rho family GTPases has been considered to be one of the most promising and novel therapeutic targets for asthma. It is well known that RhoA/Rho‐kinases play an important role in the pathophysiology of asthma, including airway smooth muscle contraction, airway hyper‐responsiveness, β‐adrenergic desensitisation and airway remodelling. However, recent advances have suggested novel roles for RhoA in regulating allergic airway inflammation. Specifically, RhoA has been shown to regulate allergic airway inflammation through controlling Th2 or Th17 cell differentiation and to regulate airway remodelling through regulating mesenchymal stem cell (MSC) differentiation. In this review, we evaluate the literature regarding the recent advances in the activation of RhoA/Rho‐kinase, cytokine and epigenetic regulation of RhoA/Rho‐kinase, and the role of RhoA/Rho‐kinase in regulating major features of asthma, such as airway hyper‐responsiveness, remodelling and inflammation. We also discuss the importance of the newly identified role of RhoA/Rho‐kinase signalling in MSC differentiation and bronchial epithelial barrier dysfunction. These findings indicate the functional significance of the RhoA/Rho‐kinase pathway in the pathophysiology of asthma and suggest that RhoA/Rho‐kinase signalling may be a promising therapeutic target for the treatment of asthma.

Nafamostat mesylate attenuates the pathophysiologic sequelae of neurovascular ischemia

Nafamostat mesylate, an apparent soi-disant panacea of sorts, is widely used to anticoagulate patients undergoing hemodialysis or cardiopulmonary bypass, mitigate the inflammatory response in patients diagnosed with acute pancreatitis, and reverse the coagulopathy of patients experiencing the commonly preterminal disseminated intravascular coagulation in the Far East. The serine protease inhibitor nafamostat mesylate exhibits significant neuroprotective effects in the setting of neurovascular ischemia. Nafamostat mesylate generates neuroprotective effects by attenuating the enzymatic activity of serine proteases, neuroinflammatory signaling cascades, and the endoplasmic reticulum stress responses, downregulating excitotoxic transient receptor membrane channel subfamily 7 cationic currents, modulating the activity of intracellular signal transduction pathways, and supporting neuronal survival (brain-derived neurotrophic factor/TrkB/ERK1/2/CREB, nuclear factor kappa B. The effects collectively reduce neuronal necrosis and apoptosis and prevent ischemia mediated disruption of blood-brain barrier microarchitecture. Investigational clinical applications of these compounds may mitigate ischemic reperfusion injury in patients undergoing cardiac, hepatic, renal, or intestinal transplant, preventing allograft rejection, and treating solid organ malignancies. Neuroprotective effects mediated by nafamostat mesylate support the wise conduct of randomized prospective controlled trials in Western countries to evaluate the clinical utility of this compound.

miR-511-3p protects against cockroach allergen-induced lung inflammation by antagonizing CCL2

miR-511-3p, encoded by CD206/Mrc1, was demonstrated to reduce allergic inflammation and promote alternative (M2) macrophage polarization. Here, we sought to elucidate the fundamental mechanism by which miR-511-3p attenuates allergic inflammation and promotes macrophage polarization. Compared with WT mice, the allergen-challenged Mrc1-/- mice showed increased airway hyperresponsiveness (AHR) and inflammation. However, this increased AHR and inflammation were significantly attenuated when these mice were pretransduced with adeno-associated virus-miR-511-3p (AAV-miR-511-3p). Gene expression profiling of macrophages identified Ccl2 as one of the major genes that was highly expressed in M2 macrophages but antagonized by miR-511-3p. The interaction between miR-511-3p and Ccl2 was confirmed by in silico analysis and mRNA-miR pulldown assay. Further evidence for the inhibition of Ccl2 by miR-511-3p was given by reduced levels of Ccl2 in supernatants of miR-511-3p-transduced macrophages and in bronchoalveolar lavage fluids of AAV-miR-511-3p-infected Mrc1-/- mice. Mechanistically, we demonstrated that Ccl2 promotes M1 macrophage polarization by activating RhoA signaling through Ccr2. The interaction between Ccr2 and RhoA was also supported by coimmunoprecipitation assay. Importantly, inhibition of RhoA signaling suppressed cockroach allergen-induced AHR and lung inflammation. These findings suggest a potentially novel mechanism by which miR-511-3p regulates allergic inflammation and macrophage polarization by targeting Ccl2 and its downstream Ccr2/RhoA axis.

Benzo(a)pyrene facilitates dermatophagoides group 1 (Der f 1)-induced epithelial cytokine release through aryl hydrocarbon receptor in asthma

BACKGROUND

Environmental pollutants, which coexist with allergens, have been associated with the exacerbation of asthma. However, the underlying molecular mechanisms remain elusive. We sought to determine whether benzo(a)pyrene (BaP) co-exposure with dermatophagoides group 1 allergen (Der f 1) can potentiate Der f 1-induced asthma and its underlying mechanisms.

METHODS

The effect of BaP was investigated in Der f 1-induced mouse model of asthma, including airway hyper-responsiveness, allergic inflammation, and epithelial-derived cytokines. The impact of BaP on Der f 1-induced airway epithelial cell oxidative stress (ROS) and cytokine release was further analyzed. The role of aryl hydrocarbon receptor (AhR) signaling in BaP-promoted Der f 1-induced ROS, cytokine production, and allergic inflammation was also investigated.

RESULTS

Compared with Der f 1, BaP co-exposure with Der f 1 led to airway hyper-responsiveness and increased lung inflammation in mouse model of asthma. Increased expression of TSLP, IL-33, and IL-25 was also found in the airways of these mice. Moreover, BaP co-exposure with Der f 1 activated AhR signaling with increased expression of AhR and CYP1A1 and promoted airway epithelial ROS generation and TSLP and IL-33, but not IL-25, expression. Interestingly, AhR antagonist CH223191 or cells with AhR knockdown abrogated the increased expression of ROS, TSLP, and IL-33. Furthermore, ROS inhibitor N-acetyl-L-cysteine (NAC) also suppressed BaP co-exposure-induced expression of epithelial TSLP, IL-33, and IL-25. Finally, AhR antagonist CH223191 and NAC inhibited BaP co-exposure with Der f 1-induced lung inflammation.

CONCLUSIONS

Our findings suggest that BaP facilitates Der f 1-induced epithelial cytokine release through the AhR-ROS axis.