Extracellular acidification attenuates bronchial contraction via an autocrine activation of EP2 receptor: Its diminishment in murine experimental asthma.

PURPOSE: Extracellular acidification is a major component of tissue inflammation, including airway inflammation in asthmatics. However, its physiological/pathophysiological significance in bronchial function is not fully understood. Currently, the functional role of extracellular acidification on bronchial contraction was explored. METHODS: Left main bronchi were isolated from male BALB/c mice. Epithelium-removed tissues were exposed to acidic pH under submaximal contraction induced by 10-5 M acetylcholine in the presence or absence of a COX inhibitor indomethacin (10-6 M). Effects of AH6809 (10-6 M, an EP2 receptor antagonist), BW A868C (10-7 M, a DP receptor antagonist) and CAY10441 (3×10-6 M, an IP receptor antagonist) on the acidification-induced change in tension were determined. The release of prostaglandin E2 (PGE2) from epithelium-denuded tissues in response to acidic pH was assessed using an ELISA. RESULTS: In the bronchi stimulated with acetylcholine, change in the extracellular pH from 7.4 to 6.8 caused a transient augmentation of contraction followed by a sustained relaxing response. The latter inhibitory response was abolished by indomethacin and AH6809 but not by BW A868C or CAY10441. Both indomethacin and AH6809 significantly increased potency and efficacy of acetylcholine at pH 6.8. Stimulation with low pH caused an increase in PGE2 release from epithelium-denuded bronchi. Interestingly, the acidic pH-induced bronchial relaxation was significantly reduced in a murine asthma model that had a bronchial hyperresponsiveness to acetylcholine. CONCLUSION: Taken together, extracellular acidification could inhibit the bronchial contraction via autocrine activation of EP2 receptors. The diminished acidic pH-mediated inhibition of bronchial tone may contribute to excessive bronchoconstriction in inflamed airways such as asthma.

Altered renin-angiotensin system gene expression in airways of antigen-challenged mice: ACE2 downregulation and unexpected increase in angiotensin 1-7.

OBJECTIVE: Evidence suggest that the renin-angiotensin system (RAS) is activated in people with asthma, although its pathophysiological role is unclear. Angiotensin-converting enzyme 2 (ACE2) is the major enzyme that converts angiotensin II to angiotensin 1-7 (Ang-1-7), and is also known as a receptor of SARS-CoV-2. The current study was conducted to identify the change in RAS-related gene expression in airways of a murine asthma model. METHODS: The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, the main bronchial smooth muscle (BSM) tissues were isolated. RESULTS: The KEGG pathway analysis of differentially expressed genes in our published microarray data revealed a significant change in the RAS pathway in the antigen-challenged mice. Quantitative RT-PCR analyses showed significant increases in the angiotensin II-generating enzymes (Klk1, Klk1b3 and Klk1b8) and a significant decrease in Ace2. Surprisingly, ELISA analyses revealed a significant increase in Ang-1-7 levels in bronchoalveolar lavage (BAL) fluids of the antigen-challenged animals, while no significant change in angiotensin II was observed. Application of Ang-1-7 to the isolated BSMs had no effect on their isometrical tension. CONCLUSION: The expression of Ace2 was downregulated in the BSMs of OA-challenged mice, while Klk1, Klk1b3 and Klk1b8 were upregulated. Despite the downregulation of ACE2, the level of its enzymatic product, Ang-1-7, was increased in the inflamed airways, suggesting the existence of an unknown ACE2-independent pathway for Ang-1-7 production. The functional role of Ang-1-7 in the airways remains unclear.

Hyperresponsiveness to Extracellular Acidification-Mediated Contraction in Isolated Bronchial Smooth Muscles of Murine Experimental Asthma.

PURPOSE: Extracellular acidification is a major component of tissue inflammation, including airway inflammation. The extracellular proton-sensing mechanisms are inherent in various cells including airway structural cells, although their physiological and pathophysiological roles in bronchial smooth muscles (BSMs) are not fully understood. In the present study, to explore the functional role of extracellular acidification on the BSM contraction, the isolated mouse BSMs were exposed to acidic pH under contractile stimulation. METHODS AND RESULTS: The RT-PCR analyses revealed that the proton-sensing G protein-coupled receptors were expressed both in mouse BSMs and cultured human BSM cells. In the mouse BSMs, change in the extracellular pH from 8.0 to 6.8 caused an augmentation of contraction induced by acetylcholine. Interestingly, the acidic pH-induced BSM hyper-contraction was further augmented in the mice that were sensitized and repeatedly challenged with ovalbumin antigen. In this animal model of asthma, upregulations of G protein-coupled receptor 68 (GPR68) and GPR65, that were believed to be coupled with Gq and Gs proteins respectively, were observed, indicating that the acidic pH could cause hyper-contraction probably via an activation of GPR68. However, psychosine, a putative antagonist for GPR68, failed to block the acidic pH-induced responses. CONCLUSION: These findings suggest that extracellular acidification contributes to the airway hyperresponsiveness, a characteristic feature of bronchial asthma. Further studies are required to identify the receptor(s) responsible for sensing extracellular protons in BSM cells.

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.

Increased Gene expression of CCL2/CCR2 axis in bronchial smooth muscles of allergen-challenged mice.

PURPOSE: Augmented bronchial smooth muscle (BSM) contraction is a cause of airway hyperresponsiveness (AHR) in asthma. Increasing evidence suggest that C-C motif chemokine 2 (CCL2) modulates smooth muscle contractility by activating its binding partner C-C chemokine receptor type 2 (CCR2). In the present study, changes in the gene expression of CCL2/CCR2 axis were determined in the BSMs of a murine model of allergic asthma. MATERIALS AND METHODS: The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, total RNAs of the main BSM tissues and bronchoalveolar lavage fluids (BALFs) were obtained. RESULTS: Our published microarray data (GEO accession No. GSE116504) detected changes in gene expression associated with the chemokine signaling pathway (KEGG Map ID: 04062) in BSMs of mice with AHR induced by antigen exposure. Among them, quantitative RT-PCR analyses showed significant increase in mRNA expression of Ccl2 and Ccr2. Analysis of BALFs also revealed a significant increase in Ccl2 protein in the airways of the diseased animals. CONCLUSION: It is thus possible that, in association with the AHR, the CCL2/CCR2 axis is enhanced in the airways of allergic bronchial asthma.

Downregulation of miR-140-3p Contributes to Upregulation of CD38 Protein in Bronchial Smooth Muscle Cells.

In allergic bronchial asthma, an increased smooth muscle contractility of the airways is one of the causes of the airway hyperresponsiveness (AHR). Increasing evidence also suggests a possible involvement of microRNAs (miRNAs) in airway diseases, including asthma, although their roles in function and pathology largely unknown. The current study aimed to determine the role of a miRNA, miR-140-3p, in the control of protein expression of CD38, which is believed to regulate the contraction of smooth muscles, including the airways. In bronchial smooth muscles (BSMs) of the mice that were actively sensitized and repeatedly challenged with ovalbumin antigen, an upregulation of CD38 protein concurrently with a significant reduction of miR-140-3p was observed. In cultured human BSM cells (hBSMCs), transfection with a synthetic miR-140-3p inhibitor caused an increase in CD38 protein, indicating that its basal protein expression is regulated by endogenous miR-140-3p. Treatment of the hBSMCs with interleukin-13 (IL-13), an asthma-related cytokine, caused both an upregulation of CD38 protein and a downregulation of miR-140-3p. Transfection of the hBSMCs with miR-140-3p mimic inhibited the CD38 protein upregulation induced by IL-13. On the other hand, neither a CD38 product cyclic ADP-ribose (cADPR) nor its antagonist 8-bromo-cADPR had an effect on the BSM contraction even in the antigen-challenged mice. Taken together, the current findings suggest that the downregulation of miR-140-3p induced by IL-13 might cause an upregulation of CD38 protein in BSM cells of the disease, although functional and pathological roles of the upregulated CD38 are still unclear.

Intranasal administration of recombinant progranulin inhibits bronchial smooth muscle hyperresponsiveness in mouse allergic asthma.

Progranulin (PGRN) is a growth factor with multiple biological functions and has been suggested as an endogenous inhibitor of Tumor necrosis factor-α (TNF-α)-mediated signaling. TNF-α is believed to be one of the important mediators of the pathogenesis of asthma, including airway hyperresponsiveness (AHR). In the present study, effects of recombinant PGRN on TNF-α-mediated signaling and antigen-induced hypercontractility were examined in bronchial smooth muscles (BSMs) both in vitro and in vivo. Cultured human BSM cells (hBSMCs) and male BALB/c mice were used. The mice were sensitized and repeatedly challenged with ovalbumin antigen. Animals also received intranasal administrations of recombinant PGRN into the airways 1 h before each antigen inhalation. In hBSMCs, PGRN inhibited both the degradation of IκB-α (an index of NF-κB activation) and the upregulation of RhoA (a contractile machinery-associated protein that contributes to the BSM hyperresponsiveness) induced by TNF-α, indicating that PGRN has an ability to inhibit TNF-α-mediated signaling also in the BSM cells. In BSMs of the repeatedly antigen-challenged mice, an augmented contractile responsiveness to acetylcholine with an upregulation of RhoA was observed: both the events were ameliorated by pretreatments with PGRN intranasally. Interestingly, a significant decrease in PGRN expression was found in the airways of the repeatedly antigen-challenged mice rather than those of control animals. In conclusion, exogenously applied PGRN into the airways ameliorated the antigen-induced BSM hyperresponsiveness, probably by blocking TNF-α-mediated response. Increasing PGRN levels might be a promising therapeutic for AHR in allergic asthma.

Interleukin-17A directly acts on bronchial smooth muscle cells and augments the contractility.

BACKGROUND: Although interleukin-17 (IL-17) contributes to the induction of airway hyperresponsiveness in asthma, its effect on bronchial smooth muscle (BSM) remains largely unknown. Evidence support an involvement of RhoA/Rho-kinase in BSM contraction, and the pathway has now been proposed as a novel target for asthma therapy. To clarify the role of IL-17 on the development of BSM hyperresponsiveness, effects of IL-17A on BSM contractility and RhoA expression were investigated. METHODS: Male BALB/c mice and cultured human BSM cells (hBSMCs) were used. RESULTS: In the murine model of allergic asthma, BSM hyperresponsiveness with an IL-17A up-regulation in bronchoalveolar lavage fluids were observed. RT-PCR analyses revealed the expression of receptors for IL-17A in mouse BSMs and hBSMCs. In the hBSMCs, incubation with IL-17A caused an up-regulation of RhoA protein. Western blot analyses also revealed phosphorylations of JNKs/ERKs and a down-regulation of IκB-α in the IL-17A-treated hBSMCs, indicating that IL-17A could act on BSM cells directly. However, IL-17A did not activate STAT6, which is also known as a signaling molecule that causes an up-regulation of RhoA when activated by IL-13. On the other hand, IL-17A caused a down-regulation of miR-133a-3p, a microRNA that negatively regulates RhoA translation. In the naive mice, in vivo IL-17A treatment to the airways by intranasal instillation induced a BSM hyperresponsiveness with RhoA protein up-regulation. CONCLUSIONS: These findings indicate that IL-17 directly acts on BSM cells and up-regulates RhoA protein probably via a down-regulation of miR-133a-3p, resulting in an induction of the BSM hyperresponsiveness.

[Anesthetic Management of the Patient with an Anterior Mediastinal Tumor].

Perioperative management of the patient with anterior mediastinal tumor is challenging and should not be underestimated. The clinical presentation of the patient is variable because it depends on the size and localiza- tion of the tumor. Therefore, it is difficult to establish a structured protocol for anesthetic management of ante- rior mediastinal tumor. Anesthesiologists are required to make careful anesthetic plan with thorough assessment of preoperative status of the patient Confirmation of "comfortable position" for the patient is important and useful for safe management The induction of general anesthesia should be performed in step-by-step wise without muscle relaxants. Even after successful tracheal intubation, difficult ventilation may occur. Preparation of percutaneous cardiopulmonary support (PCPS) is essential for the emergency situation from both respiratory and circulatory collapses, especially during anesthesia induction. For emergency use of PCPS, cannulation of femoral vessels under local anesthesia should be performed before anesthesia induction in the patient with subjective respiratory symptom and severe tracheal compression.

Effect of sugammadex on bronchial smooth muscle function in rats.

Sugammadex can encapsulate the steroid-based neuromuscular blocker molecule and results in rapid reversal of neuromuscular blockade induced by rocuronium and vecuronium. However, several cases of bronchospasm after the administration of sugammadex have been reported. The current study was carried out to determine whether sugammadex directly affects smooth muscle function of the airways. The ring strips of left main bronchi were isolated from male Wistar rats and isometric forces were measured. In the isolated bronchial smooth muscle tissues, sugammadex (10⁻8-10⁻³ M) had no effect on baseline tension or the acetylcholine (ACh; 30 µM)-induced sustained contraction. Moreover, sugammadex did not affect bronchial smooth muscle responsiveness to ACh. These findings indicate that sugammadex itself does not affect contractile function in bronchial smooth muscle of the rat.

[The postoperative management of patients after pluropneumonectomy--influence of the mode of the operation].

BACKGROUND: In our hospital, a new mode of operation was introduced in pleuropneumonectomy from 2004. We studied how these changes had affected postoperative management of patients after pleuropneumonectomy. METHODS: We retrospectively reviewed 22 patients who had undergone pleuropneumonectomy for malignant pleural mesothelioma from 2001 to 2008. They were divided into two groups; those before 2003 (n = 6) and those after 2004 (n = 16). RESULTS: After 2004, the amount of infusion, amount of blood transfusion and bleeding until POD1 were less, and the amount of urine output was more than that before 2003. But no significant complications were observed. CONCLUSIONS: The new mode of operation produced great improvement in immediate postoperative management. It is necessary to investigate if the new mode of operation improved prognosis and prevented perioperative complications.

Angiotensin II induces hyperresponsiveness of bronchial smooth muscle via an activation of p42/44 ERK in rats.

Angiotensin II (Ang II) might be an important mediator in the pathogenesis of bronchial asthma, although the mechanisms of airway hyperresponsiveness caused by Ang II are not yet clear. Whether p42/44 ERK contributes to the Ang II-elicited bronchial smooth muscle (BSM) hyperresponsiveness in rats was presently examined. The RT-PCR analyses revealed that Ang II AT(1A), AT(1B), and AT(2) receptors, angiotensinogen, angiotensin-converting enzyme, but not renin, were expressed in the lungs, trachea, and main bronchi of rats. Only a small and transient contraction was induced by the application of Ang II in the main bronchial smooth muscle; the contraction was inhibited by losartan, an AT(1) receptor antagonist. The contractions induced by carbachol (CCh), high K(+) depolarization, and sodium fluoride (NaF; a G protein activator) were augmented by pretreatment with Ang II. The BSM hyperresponsiveness induced by Ang II was abolished by losartan. Furthermore, the Ang II-induced BSM hyperresponsiveness to CCh was attenuated by pretreatment with U-0126, a p42/44 ERK kinase (MEK-1/2) inhibitor. In conclusion, Ang II-induced BSM hyperresponsiveness through the activation of p42/44 ERK may play an important role in the pathophysiology of bronchial asthma, although Ang II itself caused a small force development in the bronchial smooth muscle.

Inhibition of geranylgeranyltransferase inhibits bronchial smooth muscle hyperresponsiveness in mice.

Recent studies revealed an involvement of RhoA/Rho-kinase in the contraction of bronchial smooth muscle (BSM), and this pathway has now been proposed as a new target for asthma therapy. A posttranslational geranylgeranylation of RhoA is required for its activation. Thus selective inhibition of geranylgeranyltransferase may be a novel strategy for treatment of the BSM hyperresponsiveness in asthmatics. To test this hypothesis, we investigated the effect of a geranylgeranyltransferase inhibitor, GGTI-2133, on antigen-induced BSM hyperresponsiveness by using mice with experimental asthma. Mice were sensitized and repeatedly challenged with ovalbumin antigen. Animals also were treated with GGTI-2133 (5 mg/kg ip) once a day before and during the antigen inhalation period. Repeated antigen inhalation caused a BSM hyperresponsiveness to acetylcholine with the increased expressions of RhoA and the anti-farnesyl-positive 21-kDa proteins, probably geranylgeranylated RhoA. The in vivo GGTI-2133 treatments significantly inhibited BSM hyperresponsiveness induced by antigen exposure. In another series of experiments, BSM tissues isolated from the repeatedly antigen-challenged mice were cultured for 48 h in the absence or presence of GGTI-2133. Under these conditions, the putative geranylgeranylated RhoA was decreased in a GGTI-2133 concentration-dependent manner. The in vitro incubation with GGTI-2133 also inhibited BSM hyperresponsiveness induced by antigen exposure. These findings suggest that GGTI-2133 inhibits antigen-induced BSM hyperresponsiveness, probably by reducing downstream signal transduction of RhoA. Selective geranylgeranyltransferase inhibitors may be beneficial for the treatment of airway hyperresponsiveness, one of the characteristic features of allergic bronchial asthma.

Anesthetic management of a patient with Alport-leiomyomatosis syndrome.

We report the anesthetic management of esophagectomy for a patient with Alport-leiomyomatosis syndrome. A 23-year-old woman complained of dysphagia and severe chest pain. Her chest X-ray, computed tomography (CT), and magnetic resonance imaging (MRI) showed an enlarged esophagus, in contact with the trachea, heart, aorta, and large vessels. She frequently experienced severe asthma attacks. Because various risks in both respiration and circulation, especially in anesthesia induction, were of concern, her right femoral vessels were exposed, for the emergency use of percutaneous cardiopulmonary support (PCPS), prior to anesthesia induction. Anesthesia was induced and maintained with propofol, fentanyl, and vecuronium. Esophagectomy was performed uneventfully and no severe events were seen in anesthesia management. Alportleiomyomatosis syndrome is a very rare disease. When we are involved in the anesthetic management of a patient with this disease, evaluation of the influence of the enlarged esophagus on both respiration and circulation, and careful preparation for emergence, are very important.

Favorable outcomes after living-donor lobar lung transplantation in ventilator-dependent patients.

PURPOSE: Living-donor lobar lung transplantation (LDLLT) is performed in critically ill patients, although the outcome is generally expected to be poor for those who are ventilator dependent. The aim of this study was to compare the outcomes of LDLLT in ventilator-dependent patients compared with those in ventilator-independent patients. METHODS: We reviewed 31 consecutive patients who received LDLLT between October 1998 and May 2004. RESULTS: Five patients were ventilator dependent and 26 were ventilator independent. All five ventilator-dependent patients were female, with a mean age of 29.6 years. The duration of preoperative ventilation was 23.4 +/- 5.7 days. The underlying diagnoses in the ventilator-dependent patients included only obstructive (n = 3) and infectious lung diseases (n = 2), whereas those in the ventilator-independent patients included hypertensive and restrictive diseases (P = 0.004). There were no significant differences between the groups in early postoperative clinical values. The incidences of acute rejection and bronchiolitis obliterans syndrome (BOS) were comparable. The 5-year survival rates were 100% for the ventilator-dependent patients and 92.3% for the ventilator-independent patients (P = 0.45). CONCLUSION: Our findings suggest that LDLLT can have a favorable outcome in selected ventilator-dependent patients.

Rho-kinase inhibitors augment the inhibitory effect of propofol on rat bronchial smooth muscle contraction.

BACKGROUND: Airway smooth muscle contraction is not caused by the increase in intracellular Ca(2+) ([Ca(2+)](i)) alone because agonist stimulation increases tension at the same [Ca(2+)](i) (increase in Ca(2+) sensitivity). The small G protein Rho A and Rho-kinase (ROCK) play important roles in the regulation of Ca(2+) sensitivity. In this study, we investigated the effects of three ROCK inhibitors (fasudil, Y-27632, and H-1152) on rat airway smooth muscle contraction and the effects of ROCK inhibitors on propofol-induced bronchodilatory effects. METHODS: Ring strips from intrapulmonary bronchus of male Wistar rats were placed in 400-microL organ baths containing Krebs-Henseleit solution. After obtaining stable contraction with 30 microM acetylcholine, (1) propofol (1 microM-1 mM) was cumulatively applied; (2) cumulative doses of Y-27632 (0.01-300 microM), fasudil (0.01-100 microM), or H-1152 (0.01-100 microM) were applied; (3) propofol (1 microM-1 mM), with Y-27632, fasudil or H-1152 (0.03 microM or 0.1 microM), was cumulatively applied. RESULTS: (1) Propofol produced concentration-dependent relaxation of rat bronchial smooth muscle. (2) All ROCK inhibitors produced concentration-dependent relaxation. (3) 0.03 microM Y-27632 and fasudil had no significant effect on the concentration-response curve for propofol, while 0.1 microM of both agents significantly shifted concentration-response curves to the left and decreased EC(50). H-1152 (both 0.03 microM and 0.1 microM) significantly sifted the concentration-response curve for propofol to the left and decreased EC(50). CONCLUSIONS: ROCK inhibitors, especially H-1152, can attenuate the contraction of rat airway smooth muscle. The combined use of ROCK inhibitors and propofol causes greater relaxation.

Y-27632 augments the isoflurane-induced relaxation of bronchial smooth muscle in rats.

Recent studies revealed an involvement of RhoA/Rho-kinase signaling in the agonist-induced Ca(2+) sensitization of bronchial smooth muscle contraction, and the pathway has now been proposed as a new target for the treatment of airway obstructive diseases, such as asthma. On the other hand, volatile anesthetics such as isoflurane are traditionally used to treat status asthmaticus. In the present study, the effect of inhibition of Rho-kinase on the isoflurane-induced relaxation of bronchial smooth muscle was investigated. Smooth muscle strips of intrapulmonary bronchi obtained from Wistar rats were used. Application of isoflurane (0.5-4.0%, generated by a calibrated vaporizer) to the acetylcholine (30 microM)-precontracted rat bronchial smooth muscles caused a concentration-dependent relaxation. Interestingly, the isoflurane-induced relaxation was significantly augmented by the pretreatment with subthreshold concentration of Y-27632, a Rho-kinase inhibitor. Thus, the combined use of Y-27632 and isoflurane might be useful for treatment of severe airway blockade, such as status asthmaticus.