Augmentation of endothelin-1-induced phosphorylation of CPI-17 and myosin light chain in bronchial smooth muscle from airway hyperresponsive rats

Regulation of IL-17A and implications for TGF-β1 comodulation of airway smooth muscle remodeling in severe asthma

Severe asthma develops as a result of heightened, persistent symptoms that generally coincide with pronounced neutrophilic airway inflammation. In individuals with severe asthma, symptoms are poorly controlled by high-dose inhaled glucocorticoids and often lead to elevated morbidity and mortality rates that underscore the necessity for novel drug target identification that overcomes limitations in disease management. Many incidences of severe asthma are mechanistically associated with T helper 17 (T_H17) cell-derived cytokines and immune factors that mediate neutrophilic influx to the airways. T_H17-secreted interleukin-17A (IL-17A) is an independent risk factor for severe asthma that impacts airway smooth muscle (ASM) remodeling. T_H17-derived cytokines and diverse immune mediators further interact with structural cells of the airway to induce pathophysiological processes that impact ASM functionality. Transforming growth factor-β1 (TGF-β1) is a pivotal mediator involved in airway remodeling that correlates with enhanced T_H17 activity in individuals with severe asthma and is essential to T_H17 differentiation and IL-17A production. IL-17A can also reciprocally enhance activation of TGF-β1 signaling pathways, whereas combined T_H1/T_H17 or T_H2/T_H17 immune responses may additively impact asthma severity. This review seeks to provide a comprehensive summary of cytokine-driven T cell fate determination and T_H17-mediated airway inflammation. It will further review the evidence demonstrating the extent to which IL-17A interacts with various immune factors, specifically TGF-β1, to contribute to ASM remodeling and altered function in T_H17-driven endotypes of severe asthma.

Roles and mechanisms of TRPC3 and the PLCγ/PKC/CPI-17 signaling pathway in regulating parturition

The aim of the current study was to investigate the role of phospholipase C (PLC)γ/protein kinase C (PKC)/C-kinase-activated protein phosphatase-1 (CPI-17) signaling pathways in uterine smooth muscle during parturition. Samples of uterine tissue were collected from pregnant patients who underwent a caesarean section for preterm delivery, full-term delivery with labor onset, full-term delivery without labor onset, and from a non-pregnant control group undergoing surgery for cervical intraepithelial neoplasia III. Immunohistochemistry, and western blotting were used to assess the association between TRPC3 levels and parturition and the influence of calcium ion channels. In addition, pregnant mice were used to explore the effect of uterine canonical transient receptor potential 3 (TRPC3) expression on the parturition-triggering mechanism and PLCγ/PKC/CPI-17 signaling pathways. Pregnant mouse uterine smooth muscle cells were cultivated, with and without TRPC3 silencing, and the expression levels of PLCγ, PKC and CPI-17, the upstream and downstream factors of the TRPC3 pathway, were measured in pregnant mouse uterine smooth muscle cells, in order to provide a theoretical basis for the prevention and treatment of premature labor. In the preterm and full-term without labor onset patient groups, the TRPC3 gene expression in the mSMCs was significantly overexpressed when compared with the non-pregnant group (P<0.05); however, TRPC3 expression was not elevated in the full-term with labor onset group, exhibiting no significant difference compared with the non-pregnant group (P>0.05). During pregnancy, compared with the non-pregnant controls, Ca_v1.2, Ca_v3.1 and Ca_v3.2 gene expression levels were markedly increased (P<0.05) in mSMCs from the preterm delivery group and the full-term with labor onset group, however were non-significantly increased in the full-term without labor onset group. The level of TRPC3 was highest in the preterm group, while the levels of Ca_v1.2, Ca_v3.1 and Ca_v3.2 were highest in the full-term with labor onset group. In the preterm, LPS-treated preterm and full-term groups, TRPC3, MAPK, ERK1/2, P-ERK, Ca_v3.2, Ca_v3.1 and Ca_v1.2 were all expressed at higher levels than in the unfertilized group. In the LPS-treated preterm group, the levels of TRPC3, MAPK, ERK1/2, P-ERK, Ca_v3.2, Ca_v3.1 and Ca_v1.2 were increased compared with the preterm group. Furthermore, following transfection of small interfering TRPC3 (siTRPC3) into cells, it was demonstrated that the levels of TRPC3, PLCγ, PKC, CPI-17, P-CPI-17, Ca_v1.2, Ca_v3.1 and Ca_v3.2 expression were lower in the LPS siTRPC3 group when compared with that of the LPS-treated untransfected control group.

Endothelin-1 induces VCAM-1 expression-mediated inflammation via receptor tyrosine kinases and Elk/p300 in human tracheal smooth muscle cells

The elevated level of endothelin-1 (ET-1) has been detected in the bronchoalveolar lavage of patients with severe asthma, acute lung injury, acute respiratory distress syndrome, and sepsis. ET-1 may affect vessel tone together with lung physiology and pathology. Vascular cell adhesion molecule-1 (VCAM-1) is one kind of adhesion molecules participating in the process of polymorphonuclear leukocyte transmigration and regulating the occurrence and amplification of tissue inflammation. However, the molecular mechanisms underlying ET-1-mediated expression of VCAM-1 on human tracheal smooth muscle cells (HTSMCs) were largely unknown. Here we reported that ET-1 stimulated expression of VCAM-1 gene on HTSMCs, which was blocked by pretreatment with the inhibitors of ET receptors, Src, matrix metalloproteinases (MMPs), epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), phosphatidylinositol 3-kinase (PI3K), AKT, MEK1/2, and p300, suggesting the participation of these signaling components in ET-1-regulated HTSMC responses. Furthermore, transfection with small-interfering RNA (siRNA) of Src, AKT, p42 mitogen-activated protein kinase (MAPK), or p300 downregulated the respective proteins and significantly attenuated ET-1-induced VCAM-1 expression. ET-1 also stimulated phosphorylation of Src, EGFR, PDGFR, AKT, p42/p44 MAPK, and Elk-1 and acetylation of histone H4 on HTSMCs. Immunoprecipitation assay showed the association between Elk-1 and p300 in the nucleus. Adhesion assay revealed that the adhesion of THP-1 to HTSMCs challenged with ET-1 was increased, which was attenuated by the inhibitors of ET receptors, Src, MMPs, EGFR, PDGFR, PI3K, AKT, p42/p44 MAPK, and p300. Taken together, these data suggested that ET-1 promotes occurrence and amplification of pathology-related airway inflammation via enhancing VCAM-1 expression in an ET receptor/Src/MMP/EGFR, PDGFR/PI3K/AKT/p42/p44 MAPK/Elk-1/p300 pathway in HTSMCs.

Smooth muscle-selective CPI-17 expression increases vascular smooth muscle contraction and blood pressure

Recent data revealed that protein kinase C-potentiated myosin phosphatase inhibitor of 17 kDa (CPI-17), a myosin phosphatase inhibitory protein preferentially expressed in smooth muscle, is upregulated/activated in several diseases but whether this CPI-17 increase plays a causal role in pathologically enhanced vascular smooth muscle contractility and blood pressure remains unclear. To address this possibility, we generated a smooth muscle-specific CPI-17 transgenic mouse model (CPI-17-Tg) and demonstrated that the CPI-17 transgene was selectively expressed in smooth muscle-enriched tissues, including mesenteric arteries. The isometric contractions in the isolated second-order branch of mesenteric artery helical strips from CPI-17-Tg mice were significantly enhanced compared with controls in response to phenylephrine, U-46619, serotonin, ANG II, high potassium, and calcium. The perfusion pressure increases in isolated perfused mesenteric vascular beds in response to norepinephrine were also enhanced in CPI-17-Tg mice. The hypercontractility was associated with increased phosphorylation of CPI-17 and 20-kDa myosin light chain under basal and stimulated conditions. Surprisingly, the protein levels of rho kinase 2 and protein kinase Cα/δ were significantly increased in CPI-17-Tg mouse mesenteric arteries. Radiotelemetry measurements demonstrated that blood pressure was significantly increased in CPI-17-Tg mice. However, no vascular remodeling was detected by morphometric analysis. Taken together, our results demonstrate that increased CPI-17 expression in smooth muscle promotes vascular smooth muscle contractility and increases blood pressure, implicating a pathological significant role of CPI-17 upregulation.

Regulation of GPCR-mediated smooth muscle contraction: implications for asthma and pulmonary hypertension

Contractile G-protein-coupled receptors (GPCRs) have emerged as key regulators of smooth muscle contraction, both under healthy and diseased conditions. This brief review will discuss some key topics and novel insights regarding GPCR-mediated airway and vascular smooth muscle contraction as discussed at the 7th International Young Investigators' Symposium on Smooth Muscle (2011, Winnipeg, Manitoba, Canada) and will in particular focus on processes driving Ca(2+)-mobilization and -sensitization.

Uridine adenosine tetraphosphate induces contraction of airway smooth muscle

Contraction of airway smooth muscle (ASM) plays an important role in the regulation of air flow and is potentially involved in the pathophysiology of certain respiratory diseases. Extracellular nucleotides regulate ASM contraction via purinergic receptors, but the signaling mechanisms involved are not fully understood. Uridine adenosine tetraphosphate (Up(4)A) contains both pyrimidine and purine moieties, which are known to potentially activate P2X and P2Y receptors. Both P2X and P2Y receptors have been identified in the lung, including airway epithelial cells and ASM. We report here a study of purinergic signaling in the respiratory system, with a focus on the effect of Up(4)A on ASM contraction. Up(4)A induced contraction of rat isolated trachea and extrapulmonary bronchi as well as human intrapulmonary bronchioles. Up(4)A-induced contraction was blocked by di-inosine pentaphosphate, a P2X antagonist, but not by suramin, a nonselective P2 antagonist. Up(4)A-induced contraction was also attenuated by α,β-methylene-ATP-mediated P2X receptor desensitization. Several P2X receptors were detected at the mRNA level: P2X1, P2X4, P2X6, and P2X7, and to a lesser extent P2X3. Furthermore, the Up(4)A response was inhibited by removal of extracellular Ca(2+) and by the presence of the L-type Ca(2+) channel blocker, nifedipine, or the Rho-associated kinase inhibitor, H1152. We conclude that Up(4)A stimulates ASM contraction, and the underlying signaling mechanism appears to involve P2X (most likely P2X1) receptors, extracellular Ca(2+) entry via L-type Ca(2+) channels, and Ca(2+) sensitization through the RhoA/Rho-associated kinase pathway. This study will add to our understanding of the pathophysiological roles of extracellular nucleotides in the lung.

A functional interaction between CPI-17 and RACK1 proteins in bronchial smooth muscle cells

CPI-17 is a phosphorylation-dependent inhibitor of smooth muscle myosin light chain. Using yeast two-hybrid system, we have identified the receptor for activated C kinase 1 (RACK1) as a novel interaction partner of CPI-17. The direct interaction and co-localization of CPI-17 with RACK1 were confirmed by immunoprecipitation and confocal microscopy analysis, respectively. An in vitro assay system using recombinant/purified proteins revealed that the PKC-mediated phosphorylation of CPI-17 was augmented in the presence of RACK1. These results suggest that RACK1 may play a role in PKC/CPI-17 signaling pathway.

Airway smooth muscle as a model for new investigative drugs in asthma

Bronchial asthma as such exists because airway smooth muscle (ASM) contracts excessively in response to various stimuli. After several decades during which research was mainly focused on airway inflammation, increasing attention is now being paid to a possible abnormal behaviour of ASM. Thus, ASM is regarded as a major target for anti-asthma treatments. This review first describes the mechanisms of ASM contraction and airway hyperresponsiveness, through cellular, animal and human models. The developments of new drugs targeting extra and/or intracellular pathway of ASM contraction are discussed.

Molecular mechanisms underlying airway smooth muscle contraction and proliferation: implications for asthma

Airway smooth muscle (ASM) plays a key role in bronchomotor tone, as well as in structural remodeling of the bronchial wall. Therefore, ASM contraction and proliferation significantly participate in the development and progression of asthma. Many contractile agonists also behave as mitogenic stimuli, thus contributing to frame a hyperresponsive and hyperplastic ASM phenotype. In this review, the molecular mechanisms and signaling pathways involved in excitation-contraction coupling and ASM cell growth will be outlined. Indeed, the recent advances in understanding the basic aspects of ASM biology are disclosing important cellular targets, currently explored for the implementation of new, more effective anti-asthma therapies.

Glucocorticoids inhibited airway hyperresponsiveness through downregulation of CPI-17 in bronchial smooth muscle

Glucocorticoids are the most effective anti-inflammatory treatment for asthma, and inhaled corticosteroids are the most effective long-term control therapy for persistent asthma. In the present study, to determine the mechanism of the inhibitory effect of glucocorticoids on airway hyperresponsiveness, the effects of glucocorticoids on the expression and activation of PKC-potentiated protein phosphatase 1 inhibitory protein of 17 kDa (CPI-17) were examined in bronchial smooth muscles of antigen-induced airway hyperresponsive rats. Repeated antigen inhalation to animals sensitized with DNP-Ascaris antigen caused a marked bronchial smooth muscle hyperresponsiveness to acetylcholine, accompanied by upregulation and acetylcholine-induced activation of CPI-17 to result in an increase in myosin light chain (MLC) phosphorylation. Treatment with glucocorticoids (prednisolone or beclomethasone, 10 mg/kg, i.p., respectively) significantly inhibited the airway hyperresponsiveness, and markedly reduced both the protein and mRNA levels of CPI-17 in bronchial smooth muscle. The acetylcholine-induced activation of CPI-17, i.e., phosphorylation of CPI-17, was also significantly inhibited by glucocorticoids. Glucocorticoids also prevented the augmented acetylcholine-induced MLC phosphorylation observed in the airway hyperresponsive rats. Therefore, glucocorticoids might inhibit the airway hyperresponsiveness through the inhibition of overexpression and activation of CPI-17.

Trauma, PTSD, and physical health: an epidemiological study of Australian Vietnam veterans

OBJECTIVE

This study aimed to examine the relative contributions to physical health of combat trauma exposure and posttraumatic stress disorder (PTSD), which have both been implicated separately in poorer physical health but whose unconfounded effects have not been teased out.

METHODS

Data from an epidemiological study of Australian Vietnam veterans, which used personal interviews and standardized physical and psychiatric health assessments, provided the means to assess the independent and joint effects of psychological trauma exposure and PTSD on a wide range of self-reported measures of physical health. Trauma exposure was measured by published scales of combat exposure and peritraumatic dissociation. Logistic regression modeling was used to assess the relative importance of trauma exposure and PTSD to health while controlling for a set of potential confounders including standardized psychiatric diagnoses.

RESULTS

Greater health service usage and more recent health actions were associated more strongly with PTSD, which was also associated with a range of illness conditions coded by the World Health Organization International Classification of Diseases, 9th Edition (asthma, eczema, arthritis, back and other musculoskeletal disorders, and hypertension) both before and after controlling for potential confounders. In contrast, combat exposure and peritraumatic dissociation were more weakly associated with a limited number of unconfounded physical health outcomes.

CONCLUSIONS

This study provided evidence that PTSD, rather than combat exposure and peritraumatic dissociation, is associated with a pattern of physical health outcomes that is consistent with altered inflammatory responsiveness.