Cytoskeleton changes of airway smooth muscle cells in juvenile rats with airway remodeling in asthma and the RhoA/ROCK signaling pathway mechanism

Rho-Kinase Inhibition of Active Force and Passive Tension in Airway Smooth Muscle: A Strategy for Treating Airway Hyperresponsiveness in Asthma

Rho-kinase inhibitors have been identified as a class of potential drugs for treating asthma because of their ability to reduce airway inflammation and active force in airway smooth muscle (ASM). Past research has revealed that, besides the effect on the ASM's force generation, rho-kinase (ROCK) also regulates actin filament formation and filament network architecture and integrity, thus affecting ASM's cytoskeletal stiffness. The present review is not a comprehensive examination of the roles played by ROCK in regulating ASM function but is specifically focused on passive tension, which is partially determined by the cytoskeletal stiffness of ASM. Understanding the molecular basis for maintaining active force and passive tension in ASM by ROCK will allow us to determine the suitability of ROCK inhibitors and its downstream enzymes as a class of drugs in treating airway hyperresponsiveness seen in asthma. Because clinical trials using ROCK inhibitors in the treatment of asthma have yet to be conducted, the present review focuses on the in vitro effects of ROCK inhibitors on ASM's mechanical properties which include active force generation, relaxation, and passive stiffness. The review provides justification for future clinical trials in the treatment of asthma using ROCK inhibitors alone and in combination with other pharmacological and mechanical interventions.

Cell response to mechanical microenvironment cues via Rho signaling: From mechanobiology to mechanomedicine

Mechanical cues in the cell microenvironment such as those from extracellular matrix properties, stretching, compression and shear stress, play a critical role in maintaining homeostasis. Upon sensing mechanical stimuli, cells can translate these external forces into intracellular biochemical signals to regulate their cellular behaviors, but the specific mechanisms of mechanotransduction at the molecular level remain elusive. As a subfamily of the Ras superfamily, Rho GTPases have been recognized as key intracellular mechanotransduction mediators that can regulate multiple cell activities such as proliferation, migration and differentiation as well as biological processes such as cytoskeletal dynamics, metabolism, and organ development. However, the upstream mechanosensors for Rho proteins and downstream effectors that respond to Rho signal activation have not been well illustrated. Moreover, Rho-mediated mechanical signals in previous studies are highly context-dependent. In this review, we systematically summarize the types of mechanical cues in the cell microenvironment and provide recent advances on the roles of the Rho-based mechanotransduction in various cell activities, physiological processes and diseases. Comprehensive insights into the mechanical roles of Rho GTPase partners would open a new paradigm of mechanomedicine for a variety of diseases. STATEMENT OF SIGNIFICANCE: In this review, we highlight the critical role of Rho GTPases as signal mediators to respond to physical cues in microenvironment. This article will add a distinct contribution to this set of knowledge by intensively addressing the relationship between Rho signaling and mechanobiology/mechanotransduction/mechanomedcine. This topic has not been discussed by the journal, nor has it yet been developed by the field. The comprehensive picture that will develop, from molecular mechanisms and engineering methods to disease treatment strategies, represents an important and distinct contribution to the field. We hope that this review would help researchers in various fields, especially clinicians, oncologists and bioengineers, who study Rho signal pathway and mechanobiology/mechanotransduction, understand the critical role of Rho GTPase in mechanotransduction.

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.

Targeting of G-protein coupled receptor 40 alleviates airway hyperresponsiveness through RhoA/ROCK1 signaling pathway in obese asthmatic mice

Obesity increases the severity of airway hyperresponsiveness (AHR) in individuals with asthma, but the mechanism is not well elucidated. G-protein coupled receptor 40 (GPR40) has been found to induce airway smooth muscle contraction after activated by long-chain fatty acids (LC-FFAs), suggesting a close correlation between GPR40 and AHR in obese. In this study, C57BL/6 mice were fed a high-fat diet (HFD) to induce obesity with or without ovalbumin (OVA) sensitization, the regulatory effects of GPR40 on AHR, inflammatory cells infiltration, and the expression of Th1/Th2 cytokines were evaluated by using a small-molecule antagonist of GPR40, DC260126. We found that the free fatty acids (FFAs) level and GPR40 expression were greatly elevated in the pulmonary tissues of obese asthmatic mice. DC260126 greatly reduced methacholine-induced AHR, ameliorated pulmonary pathological changes and decreased inflammatory cell infiltration in the airways in obese asthma. In addition, DC260126 could down-regulate the levels of Th2 cytokines (IL-4, IL-5, and IL-13) and pro-inflammatory cytokines (IL-1β, TNF-α), but elevated Th1 cytokine (IFN-γ) expression. In vitro, DC260126 could remarkedly reduce oleic acid (OA)-induced cell proliferation and migration in HASM cells. Mechanistically, the effects that DC260126 alleviated obese asthma was correlated with the down-regulation of GTP-RhoA and Rho-associated coiled-coil-forming protein kinase 1 (ROCK1). Herein, we proved that targeting of GPR40 with its antagonist helped to mitigate multiple parameters of obese asthma effectively.

Effects of Different Intervention Factors on Vascular Endothelial Growth Factor-Induced Human Airway Smooth Muscle Cell Migration

Background

Asthma airway remodeling is closely related to the abnormal migration of human airway smooth muscle cells (ASMCs), and vascular endothelial growth factor (VEGF) is involved in the pathophysiological process of asthma. This study aimed to investigate the effect of VEGF on ASMC migration through in vitro cell experiments and to intervene in ASMC migration with different asthma drugs and signaling pathway inhibitors to provide a basis for screening effective drugs for airway remodeling.

Methods

The effect of VEGF on the proliferation of ASMCs was detected by the CCK-8 method, and the effect of VEGF on the migration of ASMCs was proven by scratch and transwell assays. Different asthma drugs and signaling pathway inhibitors were used to interfere with the migration of ASMCs. The number of migrating cells was compared between the intervention and nonintervention groups.

Results

Our results showed that VEGF induction enhanced ASMC migration; pretreatment with the commonly used asthma drugs (salbutamol, budesonide, and ipratropium bromide) significantly attenuated VEGF-induced ASMC migration; and inhibitors SB203580, LY294002, and Y27632 blocked the VEGF-induced activation of p38 MAPK, PI3K, and ROCK signaling pathway targets in ASMCs and inhibited migration.

Conclusion

This study shows that the current commonly used asthma drugs salbutamol, budesonide, and ipratropium have potential value in the treatment of airway remodeling, and the p38 MAPK, PI3K, and ROCK signaling pathway targets are involved in the VEGF-induced ASMC migration process. Signaling pathway inhibitor drugs may be a new way to treat asthma-induced airway remodeling in asthma patients in the future. However, the related mechanism and safety profile still need further research.

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.

Down-regulation of miR-140-3p is a cause of the interlukin-13-induced up-regulation of RhoA protein in bronchial smooth muscle cells

The current study aimed to determine the role of a microRNA (miRNA), miR-140-3p, in the control of RhoA expression in bronchial smooth muscle cells (BSMCs). In cultured human BSMCs, incubation with interleukin-13 (IL-13) caused an up-regulation of RhoA protein concurrently with a down-regulation of miR-140-3p. Transfection of the cells with a miR-140-3p inhibitor caused an increase in basal RhoA protein level. Although a mimic of miR-140-3p had little effect on the basal RhoA level, its treatment inhibited the IL-13-induced up-regulation of RhoA. These findings suggest that RhoA expression is negatively regulated by miR-140-3p, and that the negative regulation is inhibited by IL-13 to cause an up-regulation of RhoA protein in BSMCs.

Network and co-expression analysis of airway smooth muscle cell transcriptome delineates potential gene signatures in asthma

Airway smooth muscle (ASM) is known for its role in asthma exacerbations characterized by acute bronchoconstriction and remodeling. The molecular mechanisms underlying multiple gene interactions regulating gene expression in asthma remain elusive. Herein, we explored the regulatory relationship between ASM genes to uncover the putative mechanism underlying asthma in humans. To this end, the gene expression from human ASM was measured with RNA-Seq in non-asthmatic and asthmatic groups. The gene network for the asthmatic and non-asthmatic group was constructed by prioritizing differentially expressed genes (DEGs) (121) and transcription factors (TFs) (116). Furthermore, we identified differentially connected or co-expressed genes in each group. The asthmatic group showed a loss of gene connectivity due to the rewiring of major regulators. Notably, TFs such as ZNF792, SMAD1, and SMAD7 were differentially correlated in the asthmatic ASM. Additionally, the DEGs, TFs, and differentially connected genes over-represented in the pathways involved with herpes simplex virus infection, Hippo and TGF-β signaling, adherens junctions, gap junctions, and ferroptosis. The rewiring of major regulators unveiled in this study likely modulates the expression of gene-targets as an adaptive response to asthma. These multiple gene interactions pointed out novel targets and pathways for asthma exacerbations.

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.

Mechanopharmacology of Rho-kinase antagonism in airway smooth muscle and potential new therapy for asthma

The principle of mechanopharmacology of airway smooth muscle (ASM) is based on the premise that physical agitation, such as pressure oscillation applied to an airway, is able to induce bronchodilation by reducing contractility and softening the cytoskeleton of ASM. Although the underlying mechanism is not entirely clear, there is evidence to suggest that large-amplitude stretches are able to disrupt the actomyosin interaction in the crossbridge cycle and weaken the cytoskeleton in ASM cells. Rho-kinase is known to enhance force generation and strengthen structural integrity of the cytoskeleton during smooth muscle activation and plays a key role in the maintenance of force during prolonged muscle contractions. Synergy in relaxation has been observed when the muscle is subject to oscillatory length change while Rho-kinase is pharmacologically inhibited. In this review, inhibition of Rho-kinase coupled to therapeutic pressure oscillation applied to the airways is explored as a combination 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.

Valsartan inhibits RhoA-ROCK2-MYL pathway in rat model of alcoholic cardiomyopathy

The present study aimed to investigate variations in the Ras homolog gene family, member A (RhoA)-Rho-associated protein kinase 2 (ROCK2)-myosin light chain (MYL) pathway in a rat model of alcoholic cardiomyopathy (ACM) and the role of angiotensin-converting enzyme inhibitor drugs. Rat models of ACM were established via alcoholic gavage + free access to alcohol. The structural and functional changes of the heart were analyzed by hematoxylin-eosin staining, Masson's trichrome staining, immunohistochemistry staining, western blotting and fluorescence quantitative polymerase chain reaction. A total of 16 weeks later, a decreased ejection fraction and left ventricular fractional shortening in the alcohol group compared with the control group were demonstrated resulting in an increased left ventricular end diastolic diameter. These adverse effects were ameliorated following treatment with valsartan. In addition, the alcohol group revealed a disorganized arrangement of myocardial filaments, which was improved upon treatment with valsartan. RhoA and ROCK2 protein expression significantly increased in myocardial cells in the alcohol compared with the control group. Following drug intervention with valsartan, expression of RhoA and ROCK2 proteins were inhibited in the alcohol group. Furthermore, significantly elevated RhoA and ROCK2 and decreased MYL protein and mRNA expression in the alcohol group was demonstrated compared with the control group. Administration of valsartan reversed the expression profile of RhoA, ROCK and MYL in ACM. Expression of RhoA and ROCK were elevated with downregulation of MYL resulting in heart failure. However, the angiotensin receptor antagonist diminished the expression of RhoA and ROCK and enhanced the expression of MYL. The results of the present study suggest a curative effect of valsartan in ACM.

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.

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

BACKGROUND

Numbers of mesenchymal stem cells (MSCs) are increased in the airways after allergen challenge. Ras homolog family member A (RhoA)/Rho-associated protein kinase 1 (ROCK) signaling is critical in determining the lineage fate of MSCs in tissue repair/remodeling.

OBJECTIVES

We sought to investigate the role of RhoA/ROCK signaling in lineage commitment of MSCs during allergen-induced airway remodeling and delineate the underlying mechanisms.

METHODS

Active RhoA expression in lung tissues of asthmatic patients and its role in cockroach allergen-induced airway inflammation and remodeling were investigated. RhoA/ROCK signaling-mediated MSC lineage commitment was assessed in an asthma mouse model by using MSC lineage tracing mice (nestin-Cre; ROSA26-EYFP). The role of RhoA/ROCK in MSC lineage commitment was also examined by using MSCs expressing constitutively active RhoA (RhoA-L63) or dominant negative RhoA (RhoA-N19). Downstream RhoA-regulated genes were identified by using the Stem Cell Signaling Array.

RESULTS

Lung tissues from asthmatic mice showed increased expression of active RhoA when compared with those from control mice. Inhibition of RhoA/ROCK signaling with fasudil, a RhoA/ROCK inhibitor, reversed established cockroach allergen-induced airway inflammation and remodeling, as assessed based on greater collagen deposition/fibrosis. Furthermore, fasudil inhibited MSC differentiation into fibroblasts/myofibroblasts but promoted MSC differentiation into epithelial cells in asthmatic nestin-Cre; ROSA26-EYFP mice. Consistently, expression of RhoA-L63 facilitated differentiation of MSCs into fibroblasts/myofibroblasts, whereas expression of RhoA-19 switched the differentiation toward epithelial cells. The gene array identified the Wnt signaling effector lymphoid enhancer-binding factor 1 (Lef1) as the most upregulated gene in RhoA-L63-transfected MSCs. Knockdown of Lef1 induced MSC differentiation away from fibroblasts/myofibroblasts but toward epithelial cells.

CONCLUSIONS

These findings uncover a previously unrecognized role of RhoA/ROCK signaling in MSC-involved airway repair/remodeling in the setting of asthma.

Effect of Anti-IL17 Antibody Treatment Alone and in Combination With Rho-Kinase Inhibitor in a Murine Model of Asthma

Background: Interleukin-17 (IL-17) and Rho-kinase (ROCK) play an important role in regulating the expression of inflammatory mediators, immune cell recruitment, hyper-responsiveness, tissue remodeling, and oxidative stress. Modulation of IL-17 and ROCK proteins may represent a promising approach for the treatment of this disease.

Objective: To study the effects of an anti-IL17 neutralizing antibody and ROCK inhibitor treatments, separately and in combination, in a murine model of chronic allergy-induced lung inflammation.

Methods: Sixty-four BALBc mice, were divided into eight groups (n = 8): SAL (saline-instilled); OVA (exposed-ovalbumin); SAL-RHOi (saline and ROCK inhibitor), OVA-RHOi (exposed-ovalbumin and ROCK inhibitor); SAL-anti-IL17 (saline and anti-IL17); OVA-anti-IL17 (exposed-ovalbumin and anti-IL17); SAL-RHOi-anti-IL17 (saline, ROCK inhibitor and anti-IL17); and OVA-RHOi-anti-IL17 (exposed-ovalbumin, anti-IL17, and ROCK inhibitor). A 28-day protocol of albumin treatment was used for sensitization and induction of pulmonary inflammation. The anti-IL17A neutralizing antibody (7.5 μg per treatment) was administered by intraperitoneal injection and ROCK inhibitor (Y-27632) intranasally (10 mg/kg), 1 h prior to each ovalbumin challenge (days 22, 24, 26, and 28).

Results: Treatment with the anti-IL17 neutralizing antibody and ROCK inhibitor attenuated the percentage of maximal increase of respiratory system resistance and respiratory system elastance after challenge with methacholine and the inflammatory response markers evaluated (CD4⁺, CD8⁺, ROCK1, ROCK2, IL-4, IL-5, IL-6, IL-10 IL-13, IL-17, TNF-α, TGF-β, NF-κB, dendritic cells, iNOS, MMP-9, MMP-12, TIMP-1, FOXP3, isoprostane, biglycan, decorin, fibronectin, collagen fibers content and gene expression of IL-17, VAChT, and arginase) compared to the OVA group (p < 0.05). Treatment with anti-IL17 and the ROCK inhibitor together resulted in potentiation in decreasing the percentage of resistance increase after challenge with methacholine, decreased the number of IL-5 positive cells in the airway, and reduced, IL-5, TGF-β, FOXP3, ROCK1 and ROCK2 positive cells in the alveolar septa compared to the OVA-RHOi and OVA-anti-IL17 groups (p < 0.05).

Conclusion: Anti-IL17 treatment alone or in conjunction with the ROCK inhibitor, modulates airway responsiveness, inflammation, tissue remodeling, and oxidative stress in mice with chronic allergic lung inflammation.

Neurokinin 1 receptor promotes rat airway smooth muscle cell migration in asthmatic airway remodelling by enhancing tubulin expression

Background

Airway remodelling is a major contributor to hyper-responsiveness leading to chronic asthma; however, the underlying mechanisms remain unclear. This study aimed to investigate the effects of a neurokinin 1 receptor (NK1R) antagonist (WIN62577) on the migration of airway smooth muscle cells (ASMCs) and the expression of NK1R and alpha-tubulin in airway remodelling using young rats with asthma.

Methods

Sprague-Dawley rats were randomly divided into a control group and airway remodelling group. Rats in the model group were stimulated with ovalbumin for 8 weeks. Primary ASMCs were cultured and purified from all rats, and then treated with different doses of WIN62577. The expression of NK1R and α-tubulin in ASMCs was assessed using immunofluorescence, real-time quantitative polymerase chain reaction, and western blotting. Changes in ASMC migration were detected by a transwell chamber assay.

Results

The transwell assay showed that the number of migrating ASMCs in the asthmatic airway remodelling group was significantly greater than that in the control group (P<0.01), which was inhibited by WIN62577 in a dose-dependent manner, with peak inhibition detected at 10^-8 mol/L. The mRNA and protein expression levels of NK1R and α-tubulin were significantly higher in the asthmatic airway remodelling group than in the control group (P<0.05 and P<0.01, respectively), and were significantly decreased after treatment with WIN62577 (P<0.01 and P<0.05, respectively).

Conclusions

NK1R antagonists may suppress ASMC migration in a rat model of airway remodelling by inhibiting tubulin expression, indicating a new potential target for the treatment and control of chronic asthma.

Effect of Rho-kinase inhibition on complexity of breathing pattern in a guinea pig model of asthma

Asthma represents an episodic and fluctuating behavior characterized with decreased complexity of respiratory dynamics. Several evidence indicate that asthma severity or control is associated with alteration in variability of lung function. The pathophysiological basis of alteration in complexity of breathing pattern in asthma has remained poorly understood. Regarding the point that Rho-kinase is involved in pathophysiology of asthma, in present study we investigated the effect of Rho-kinase inhibition on complexity of respiratory dynamics in a guinea pig model of asthma. Male Dunkin Hartley guinea pigs were exposed to 12 series of inhalations with ovalbumin or saline. Animals were treated by the Rho-kinase inhibitor Y-27632 (1mM aerosols) prior to each allergen challenge. We recorded respiration of conscious animals using whole-body plethysmography. Exposure to ovalbumin induced lung inflammation, airway hyperresponsiveness and remodeling including goblet cell hyperplasia, increase in the thickness of airways smooth muscles and subepithelial collagen deposition. Complexity analysis of respiratory dynamics revealed a dramatic decrease in irregularity of respiratory rhythm representing less complexity in asthmatic guinea pigs. Inhibition of Rho-kinase reduced the airway remodeling and hyperreponsiveness, but had no significant effect on lung inflammation and complexity of respiratory dynamics in asthmatic animals. It seems that airway hyperresponsiveness and remodeling do not significantly affect the complexity of respiratory dynamics. Our results suggest that inflammation might be the probable cause of shift in the respiratory dynamics away from the normal fluctuation in asthma.

Atorvastatin has a protective effect in a mouse model of bronchial asthma through regulating tissue transglutaminase and triggering receptor expressed on myeloid cells-1 expression

Airway remodeling in asthma contributes to airway hyperreactivity, loss of lung function and persistent symptoms. Current therapies do not adequately treat the structural airway changes associated with asthma. Statin drugs have improved respiratory health and their therapeutic potential in asthma has been tested in clinical trials. However, the mechanism of action of statins in this context has remained elusive. The present study hypothesized that atorvastatin treatment of ovalbumin-exposed mice attenuates early features of airway remodeling via a mevalonate-dependent mechanism. BALB/c mice were sensitized with ovalbumin and atorvastatin was delivered via oral gavage prior to each ovalbumin exposure. Reverse transcription-semi-quantitative polymerase chain reaction (RT-semi-qPCR), ELISA and western blot analysis were used to assess the expression of a number of relevant genes, including tissue transglutaminase (tTG), triggering receptor expressed on myeloid cells (TREM)-1, nuclear factor erythroid 2-related factor (Nrf) 2, hypoxia-inducible factor (HIF)-1α, transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-9 and tissue inhibitors of metalloproteinases (TIMP)-1 in lung tissue. α-Smooth muscle actin (α-SMA) activity was measured by immunohistochemistry. Airway hyperresponsiveness, lung collagen deposition, airway wall area, airway smooth muscle thickness and lung pathology were also assessed. Atorvastatin treatment led to downregulation of tTG and TREM-1 expression in lung tissue after ovalbumin sensitization, blocked the activity of MMP-9, vascular endothelial growth factor, nuclear factor-κB p65, α-SMA, HIF-α and TGF-β1 and up-regulated Nrf2 expression. Furthermore, the number of lymphocytes and eosinophils in the atorvastatin group was significantly lower than that in the control group. In addition, airway hyperresponsiveness, lung collagen deposition, airway wall area, airway smooth muscle thickness and pathological changes in the lung were significantly decreased in the atorvastatin group, and tumor necrosis factor-α, interleukin (IL)-8, IL-13 and IL-17 in serum were significantly decreased. Histological results demonstrated the attenuating effect of atorvastatin on ovalbumin-induced airway remodeling in asthma. In conclusion, the present study indicated that atorvastatin significantly alleviated ovalbumin-induced airway remodeling in asthma by downregulating tTG and TREM-1 expression. The marked protective effects of atorvastatin suggest its therapeutic potential in ovalbumin-induced airway remodeling in asthma treatment.

Rho-kinase inhibitor fasudil reduces allergic airway inflammation and mucus hypersecretion by regulating STAT6 and NFκB

BACKGROUND

Airway mucus hypersecretion is a key pathophysiological feature in asthma. Fasudil, a selective Rho-A/Rho kinase inhibitor, has been used in clinical trials to treat pulmonary hypertension. However, its function in modulating airway mucus hypersecretion in asthma remains undefined.

OBJECTIVE

We examined whether fasudil, a selective Rho-A/Rho kinase inhibitor, affects the mucus hypersecretion by suppressing MUC5AC via signal transducer and activator of transcription factor 6 (STAT6) and nuclear factor-kappa B (NFκB) in mice and cells.

METHODS

We measured mucus secretion and the expression of Rho-kinase in the airway tissue of patients with asthma. BALB/c mice were sensitized and challenged with ovalbumin (OVA) followed with fasudil treatment. The lung tissues were assessed for airway inflammation and mucus secretion. Cytokine levels and airway responsiveness were determined. STAT6 and NFκB were quantified by Western blot. 16HBE cells were stimulated with house dust mite (HDM) extracts. MUC5AC and muc5ac promoter activities were measured. Using siRNA to knockdown STAT6 in epithelial cells, we determined the impact of STAT6 on muc5ac promoter activity. NFκB nuclear translocation was observed with immunostaining.

RESULTS

Fasudil administration significantly decreased the number of inflammatory cells, inflammation index in the lung and airway responsiveness. Fasudil also reduced mucous secretion and MUC5AC expression in OVA-challenged mice. Fasudil down-regulated the levels of IL-17, IL-4 and IL-13 in the lung tissue of OVA-challenged mice. Fasudil also decreased the expression and phosphorylation of NFκB and STAT6 as well as the nuclear translocation of NFκB. In addition, human airway epithelial cells (16HBE) were challenged with HDM extracts and then treated with fasudil. Fasudil inhibited HDM extract-induced MUC5AC expression, which is associated with a reduction in STAT6 and NFκB in epithelial cells.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings indicate that the Rho-A/Rho kinase inhibitor, fasudil, plays a negative regulatory role in allergen-induced mucus secretion and MUC5AC expression by regulating STAT6 and NFκB.

HB-EGF-Promoted Airway Smooth Muscle Cells and Their Progenitor Migration Contribute to Airway Smooth Muscle Remodeling in Asthmatic Mouse

The airway smooth muscle (ASM) cells' proliferation, migration, and their progenitor's migration are currently regarded as causative factors for ASM remodeling in asthma. Heparin-binding epidermal growth factor (HB-EGF), a potent mitogen and chemotactic factor, could promote ASM cell proliferation through MAPK pathways. In this study, we obtained primary ASM cells and their progenitors from C57BL/6 mice and went on to explore the role of HB-EGF in these cells migration and the underlying mechanisms. We found that recombinant HB-EGF (rHB-EGF) intratracheal instillation accelerated ASM layer thickening in an OVA-induced asthmatic mouse. Modified Boyden chamber assay revealed that rHB-EGF facilitate ASM cell migration in a dose-dependent manner and ASM cells from asthmatic mice had a greater migration ability than that from normal counterparts. rHB-EGF could stimulate the phosphorylation of ERK1/2 and p38 in ASM cells but further migration assay showed that only epidermal growth factor receptor inhibitor (AG1478) or p38 inhibitor (SB203580), but not ERK1/2 inhibitor (PD98059), could inhibit rHB-EGF-mediated ASM cells migration. Actin cytoskeleton experiments exhibited that rHB-EGF could cause actin stress fibers disassembly and focal adhesions formation of ASM cells through the activation of p38. Finally, airway instillation of rHB-EGF promoted the recruitment of bone marrow-derived smooth muscle progenitor cells, which were transferred via caudal vein, migrating into the airway from the circulation. These observations demonstrated that ASM remodeling in asthma might have resulted from HB-EGF-mediated ASM cells and their progenitor cells migration, via p38 MAPK-dependent actin cytoskeleton remodeling.

Effect of surface topography and bioactive properties on early adhesion and growth behavior of mouse preosteoblast MC3T3-E1 cells

The effects of bioactive properties and surface topography of biomaterials on the adhesion and spreading properties of mouse preosteoblast MC3T3-E1 cells was investigated by preparation of different surfaces. Poly lactic-co-glycolic acid (PLGA) electrospun fibers (ES) were produced as a porous rough surface. In our study, coverslips were used as a substrate for the immobilization of 3,4-dihydroxyphenylalanine (DOPA) and collagen type I (COL I) in the preparation of bioactive surfaces. In addition, COL I was immobilized onto porous electrospun fibers surfaces (E-COL) to investigate the combined effects of bioactive molecules and topography. Untreated coverslips were used as controls. Early adhesion and growth behavior of MC3T3-E1 cells cultured on the different surfaces were studied at 6, 12, and 24 h. Evaluation of cell adhesion and morphological changes showed that the all the surfaces were favorable for promoting the adhesion and spreading of cells. CCK-8 assays and flow cytometry revealed that both topography and bioactive properties were favorable for cell growth. Analysis of β1, α1, α2, α5, α10 and α11 integrin expression levels by immunofluorescence, real-time RT-PCR, and Western blot and indicated that surface topography plays an important role in the early stage of cell adhesion. However, the influence of topography and bioactive properties of surfaces on integrins is variable. Compared with any of the topographic or bioactive properties in isolation, the combined effect of both types of properties provided an advantage for the growth and spreading of MC3T3-E1 cells. This study provides a new insight into the functions and effects of topographic and bioactive modifications of surfaces at the interface between cells and biomaterials for tissue engineering.