Ludwig's angina and mask use.

Ludwig angina cases that could only be recognized by unmasking.

Comparative Effects of Direct Renin Inhibitor and Angiotensin Receptor Blocker on Albuminuria in Hypertensive Patients with Type 2 Diabetes. A Randomized Controlled Trial.

BACKGROUND: In patients with diabetes, albuminuria is a risk marker of end-stage renal disease and cardiovascular events. An increased renin-angiotensin system activity has been reported to play an important role in the pathological processes in these conditions. We compared the effect of aliskiren, a direct renin inhibitor (DRI), with that of angiotensin receptor blockers (ARBs) on albuminuria and urinary excretion of angiotensinogen, a marker of intrarenal renin-angiotensin system activity. METHODS: We randomly assigned 237 type 2 diabetic patients with high-normal albuminuria (10 to <30 mg/g of albumin-to-creatinine ratio) or microalbuminuria (30 to <300 mg/g) to the DRI group or ARB group (any ARB) with a target blood pressure of <130/80 mmHg. The primary endpoint was a reduction in albuminuria. RESULTS: Twelve patients dropped out during the observation period, and a total of 225 patients were analyzed. During the study period, the systolic and diastolic blood pressures were not different between the groups. The changes in the urinary albumin-to-creatinine ratio from baseline to the end of the treatment period in the DRI and ARB groups were similar (-5.5% and -6.7%, respectively). In contrast, a significant reduction in the urinary excretion of angiotensinogen was observed in the ARB group but not in the DRI group. In the subgroup analysis, a significant reduction in the albuminuria was observed in the ARB group but not in the DRI group among high-normal albuminuria patients. CONCLUSION: DRI and ARB reduced albuminuria in hypertensive patients with type 2 diabetes. In addition, ARB, but not DRI, reduced albuminuria even in patients with normal albuminuria. DRI is not superior to ARB in the reduction of urinary excretion of albumin and angiotensinogen.

Rac1 regulates myosin II phosphorylation through regulation of myosin light chain phosphatase.

Phosphorylation of regulatory light chain (MLC) activates myosin II, which enables it to promote contractile and motile activities of cells. We report here a novel signaling mechanism that activates MLC phosphorylation and smooth muscle contraction. Contractile agonists activated Rac1, and Rac1 inhibition diminished agonist-induced MLC phosphorylation, thus inhibiting smooth muscle contraction. Rac1 inhibits the activity of MLC phosphatase (MLCP) but not that of MLC kinase, through a phosphatase that targets MYPT1 (a regulatory subunit of MLCP) and CPI-17 (a MLCP specific inhibitor) rather than through the RhoA-Rho dependent kinase (ROCK) pathway. Rac1 inhibition decreased the activity of protein kinase C (PKC), which also contributes to the change in CPI-17 phosphorylation. We propose that activation of Rac1 increases the activity of PKC, which increases the phosphorylation of CPI-17 and MYPT1 by inhibiting the phosphatase that targets these proteins, thereby decreasing the activity of MLCP and increasing phosphorylation of MLC. Our results suggest that Rac1 coordinates with RhoA to increase MLC phosphorylation by inactivation of CPI-17/MYPT1 phosphatase, which decreases MLCP activity thus promoting MLC phosphorylation and cell contraction.

Augmented bronchial smooth muscle contractility induced by aqueous cigarette smoke extract in rats.

Cigarette smoking is the main risk factor for the development of chronic obstructive pulmonary disease (COPD). However, little is known about the mechanisms of cigarette smoke-induced bronchial smooth muscle (BSM) hyperresponsiveness. In the present study, we investigated the effects of aqueous cigarette smoke extract (ACSE) on the BSM contraction in rats. The bronchial strips of rats were incubated with ACSE or control-extract for 24 h. The acetylcholine (ACh), high K(+) depolarization and sodium fluoride (NaF)-induced BSM contraction of the ACSE-treated group was significantly augmented as compared to that of the control one. The expression levels of both myosin light-chain kinase (MLCK) and RhoA were significantly increased in the ACSE-treated BSM. These findings suggest that the water-soluble components of cigarette smoke may cause BSM hyperresponsiveness via an increase in MLCK and RhoA.

Elevated guanylate cyclase and cyclic-guanosine monophosphate-dependent protein kinase levels in nasal mucosae of antigen-challenged rats.

OBJECTIVE: In patients with severe allergic rhinitis, the most serious symptom is rhinostenosis, which is considered to be induced by a dilatation of plexus cavernosum. The vascular relaxing responses to chemical mediators are mainly mediated by the production of nitric oxide (NO). However, the exact mechanism(s) in nasal venoresponsiveness of allergic rhinitis is not fully understood. In the present study, we investigated the roles of soluble guanylate cyclase (sGC) and cyclic-guanosine monophosphate (c-GMP)-dependent protein kinase G (PKG) in venodilatation of nasal mucosae of antigen-challenged rats. METHODS: Actively sensitized rats were repeatedly challenged with aerosolized antigen (2,4-dinitrophenylated Ascaris suum). Twenty-four hours after the final antigen challenge, nasal septum mucosa was exposed surgically and observed directly in vivo under a stereoscopic microscope. The sodium nitroprusside (SNP) and 8-Br-cGMP (a PKG activator) were administered into arterial injection, and the venous diameters of nasal mucosa were observed. RESULTS: The intra-arterial injections of SNP and 8-Br-cGMP-induced venodilatation were significantly augmented in the nasal mucosae of repeatedly antigen-challenged rats. Furthermore, protein expressions of sGC and PKG were significantly increased in nasal mucosae of the antigen-challenged rats. CONCLUSION: The present findings suggest the idea that the promoted cGMP/PKG pathway may be involved in the enhanced NO-induced venodilatation in nasal mucosae of antigen-challenged rats.

Involvement of the Tyr kinase/JNK pathway in carbachol-induced bronchial smooth muscle contraction in the rat.

BACKGROUND: Tyrosine (Tyr) kinases and mitogen-activated protein kinases have been thought to participate in the contractile response in various smooth muscles. The aim of the current study was to investigate the involvement of the Tyr kinase pathway in the contraction of bronchial smooth muscle. METHODS: Ring preparations of bronchi isolated from rats were suspended in an organ bath. Isometric contraction of circular smooth muscle was measured. Immunoblotting was used to examine the phosphorylation of c-Jun N-terminal kinasess (JNKs) in bronchial smooth muscle. RESULTS: To examine the role of mitogen-activated protein kinase(s) in bronchial smooth muscle contraction, the effects of MPAK inhibitors were investigated in this study. The contraction induced by carbachol (CCh) was significantly inhibited by pretreatment with selective Tyr kinase inhibitors (genistein and ST638, n = 6, respectively), and a JNK inhibitor (SP600125, n = 6). The contractions induced by high K depolarization (n = 4), orthovanadate (a potent Tyr phosphatase inhibitor) and sodium fluoride (a G protein activator; NaF) were also significantly inhibited by selective Tyr kinase inhibitors and a JNK inhibitor (n = 4, respectively). However, the contraction induced by calyculin-A was not affected by SP600125. On the other hand, JNKs were phosphorylated by CCh (2.2 ± 0,4 [mean±SEM] fold increase). The JNK phosphorylation induced by CCh was significantly inhibited by SP600125 (n = 4). CONCLUSION: These findings suggest that the Tyr kinase/JNK pathway may play a role in bronchial smooth muscle contraction. Strategies to inhibit JNK activation may represent a novel therapeutic approach for diseases involving airway obstruction, such as asthma and chronic obstructive pulmonary disease.

Interleukin-13-induced activation of signal transducer and activator of transcription 6 is mediated by an activation of Janus kinase 1 in cultured human bronchial smooth muscle cells.

BACKGROUND: The current study was carried out to identify the JAK molecule(s) that is involved in the IL-13-induced activation of STAT6 in cultured human bronchial smooth muscle cells (hBSMCs). METHODS: Cultured hBSMCs were stimulated with IL-13 in the absence and presence of JAK inhibitor-I (a nonspecific JAKs inhibitor), tyrphostin-AG490 (a specific JAK2 inhibitor), WHI-P131 (a specific JAK3 inhibitor), or tyrphostin-AG9 (a specific Tyk2 inhibitor), and levels of phosphorylated STAT6 were measured by immunoblot analyses. RESULTS: The IL-13-induced phosphorylation of STAT6 was abolished by JAK inhibitor-I, whereas the other inhibitors had no significant effect. CONCLUSION: These findings indicate that the STAT6 phosphorylation/activation induced by IL-13 is mediated by an activation of JAK1 in cultured hBSMCs.

Different effects of smoke from heavy and light cigarettes on the induction of bronchial smooth muscle hyperresponsiveness in rats.

Cigarette smoking is one of the main risk factors in the development of chronic obstructive pulmonary disease (COPD). It has been suggested that an augmented agonist-induced, RhoA mediated Ca²âº sensitization is responsible for the enhanced bronchial smooth muscle contraction induced by cigarette smoking. In the present study, to determine whether or not these phenomena are dependent on the degree of exposure to the components of cigarette smoke, we examined the effects of exposure to mainstream smoke derived from either light or heavy cigarettes on both the contractile responsiveness and the expression of RhoA in bronchial smooth muscle. Male Wistar rats were exposed to mainstream cigarette smoke for 2 hr/day for 2 weeks. Twenty-four hr after the last cigarette smoke exposure, we measured isometrical contractions of the bronchial smooth muscle. The concentration-response curve to ACh was significantly shifted upward after heavy cigarette smoke (HCS) exposure, whereas no significant difference was observed in the case of light cigarette smoke (LCS) exposure compared with control rats. No significant difference in K⁺ responsiveness was observed between the groups. The expression of RhoA protein in bronchial preparations from rats repeatedly exposed to HCS, but not to LCS, was significantly increased as compared with that of the control animals. On the other hand, inhalation of nicotine had no effect on either the ACh- and high K⁺ depolarization-induced contractions or the expression of RhoA protein. The increased expression of RhoA seems to have an important role in the augmented contractile responses of the airways in rats, a characteristic feature of early COPD.

Sphingosine-1-phosphate augments agonist-mediated contraction in the bronchial smooth muscles of mice.

The effects of sphingosine-1-phosphate (S1P) on bronchial smooth muscle (BSM) contractility were investigated in naive mice. S1P had no effect on the basal tone of the isolated BSM tissues. However, in the presence of S1P (10(-6) M), the BSM contractions induced by acetylcholine (ACh) and endothelin-1 (ET-1) were significantly augmented: both the ACh and ET-1 concentration-response curves were significantly shifted to the left. In contrast, the pretreatment with S1P had no effect on the contractions induced by high K(+) depolarization. It is thus possible that S1P augments BSM contraction induced by the activation of G protein-coupled receptors.

Antigen challenge influences various transcription factors of rat bronchus: protein/DNA array study.

Although the transcription factors are required for expression of the proinflammatory cytokines and immune proteins which are involved in airway hyperresponsiveness and inflammation of bronchial asthma, the antigen-induced alterations of the transcription factors in bronchi have not yet been revealed. Therefore, in order to profile the alteration pattern of the transcription factors after antigen challenge in bronchi, we used protein/DNA arrays. Rats were sensitized and repeatedly challenged with 2,4-dinitrophenylated Ascaris suum antigen. Half, 1, 2 and 4 h after the last antigen challenge, protein/DNA array was performed with nuclear extract of bronchial tissue. Twenty-one the transcription factors exhibited an activation after the last antigen challenge in rat bronchial tissue. Among them, upstream transcription factor-1 (USF-1) and CAAT box general (CBF) were markedly activated after the last antigen challenge. Conversely, 4 transcription factors were inactivated after the last challenge. In development of bronchial asthma, some of the transcription factors may have an ability to modulate the transcription of inflammatory proteins such as cytokines, inflammatory enzymes, etc. Furthermore, the transcription factors, such as USF-1 and CBF, which have not been taken notice so far are also presumed to play an important role in the development of bronchial asthma.

Antigen exposure causes activations of signal transducer and activator of transcription 6 (STAT6) and STAT1, but not STAT3, in lungs of sensitized mice.

The signal transducer and activator of transcription (STAT) family of molecules play a critical role in the signaling of many cytokines. In addition to STAT6, implication of STAT1 and STAT3 in the pathogenesis of allergic airway diseases has also been suggested. However, there is little information whether or not antigen challenge to sensitized animals causes the in vivo activation of STAT1 and/or STAT3 in the airways. In the present study, the activations of these STAT molecules were monitored in lungs of mice with allergic bronchial asthma. Male BALB/c mice were sensitized and repeatedly challenged with ovalbumin (OA) antigen. Total protein samples of lungs were prepared at ∼1-24 h after the last OA challenge, and western blot analyses for total and tyrosine-phosphorylated STATs (pSTATs) molecules were conducted. In addition to the phosphorylation of STAT6, STAT1 was also phosphorylated in lungs after the inhalation of OA antigen. Both the phosphorylation of STAT6 and STAT1 occurred at the early stage after the antigen exposure. In contrast, no significant increase in the level of pSTAT3 was observed in this mouse model of allergic bronchial asthma. In conclusion, the current findings suggest that STAT6 and STAT1, but not STAT3, might be crucial signal transducers in the pathogenesis of allergic bronchial asthma.

Involvement of K(+) channels in the augmented nasal venous responsiveness to nitric oxide in rat model of allergic rhinitis.

OBJECTIVE: one of the factors of nasal obstruction observed in allergic rhinitis is thought to be a dilatation of microveins in nasal mucosa, although the exact mechanism(s) is not fully understood. In nasal mucosae of repeatedly antigen challenged rats, NO-induced venodilatation itself is augmented. In the present study, the roles of K(+) channels in sodium nitroprusside (NO donor; SNP)-induced venodilatation of nasal mucosae in antigen-challenged rats were investigated. METHODS: actively sensitized rats were repeatedly challenged with aerosolized antigen. Twenty-four hours after the final antigen challenge, nasal septum mucosa was exposed surgically and observed directly in vivo under a stereoscopic microscope. The 20µl reagents were administered onto the exposed septal mucosal surface, and the venous diameters of nasal mucosa were observed. RESULTS: the SNP-induced venodilatation of septal mucosa was markedly and significantly increased in the antigen-challenged rats. The SNP-induced venodilatation was significantly inhibited by pretreatment with either tetraethylammonium [TEA; a large-conductance Ca(2+) activated-K(+) (K(Ca)) and voltage dependent K(+) (Kv) channel inhibitor] or glibenclamide [an ATP sensitive K(+) (K(ATP)) channel inhibitor]. CONCLUSIONS: these findings suggest that NO-induced venodilatation is augmented in nasal mucosae of challenged rats, and K(+) channels play an important role in the augmented venous responsiveness to NO in nasal mucosae of repeatedly antigen challenged rats.

Involvement of multiple PKC isoforms in phorbol 12,13-dibutyrate-induced contraction during high K(+) depolarization in bronchial smooth muscle of mice.

In airway smooth muscle, protein kinase C (PKC) has been implicated in a number of functional responses including the regulation of contractility. However, the exact role of PKC on bronchial smooth muscle (BSM) contraction is still unclear. In the present study, to determine the role of PKC activation in the BSM contraction, the effects of phorbol 12,13-dibutyrate (PDBu, a direct PKC activator) on BSM tone were examined in the absence and presence of K(+)-induced depolarization stimulation. The force development was not evoked by treatment with 1 µM PDBu alone. However, a strong contraction was induced by PDBu during high K(+) contraction. The contraction induced by PDBu during high K(+) stimulation was significantly abolished by pretreatment with nicardipine, an L-type voltage dependent Ca(2+) channel blocker. In RT-PCR analysis, mRNAs of PKCα, ß, γ, δ, ε, η and θ isoforms were detected in mouse BSM. Gö6976 (an inhibitor of PKCs α and ß) and rottlerin (an inhibitor of PKCδ) significantly but partially inhibited the PDBu-induced BSM contraction during K(+) stimulation. GF109203X (an inhibitor of PKCs α, ß, γ, and ε) completely inhibited the PDBu-induced contraction during K(+) stimulation. In conclusion, it is suggested that the PDBu-induced BSM contraction is dependent on an increase in cytosolic Ca(2+). Furthermore, it is possible that both cPKC and nPKC(s) participate in the PDBu-induced contraction of mouse BSM during K(+) stimulation.

Augmented PDBu-mediated contraction of bronchial smooth muscle of mice with antigen-induced airway hyperresponsiveness.

To explore the role of protein kinase C (PKC) in the augmented bronchial smooth muscle (BSM) contraction observed in the antigen-induced airway hyperresponsive (AHR) mice, the effects of a PKC activator, phorbol 12,13-dibutylate (PDBu), on BSM contraction were compared between the AHR and control mice. Actively sensitized mice were repeatedly challenged by antigen inhalation. Twenty-four hours after the final antigen challenge the isometrical contractions of the BSMs were measured. The BSM contraction induced by acetylcholine, but not high K(+) depolarization, was significantly augmented in the AHR mice. In BSMs of control mice, PDBu caused a significant increase in tension when the tissues were precontracted with high K(+), although PDBu itself had no effect on basal tone. The PDBu-mediated contraction was markedly augmented in BSMs of the AHR mice. These findings suggest that an increase in the PKC-mediated signaling is involved in the augmented contraction of BSMs in the antigen-induced AHR mice.

RhoA, a possible target for treatment of airway hyperresponsiveness in bronchial asthma.

Airway hyperresponsiveness to nonspecific stimuli is one of the characteristic features of allergic bronchial asthma. An elevated contractility of bronchial smooth muscle has been considered as one of the causes of the airway hyperresponsiveness. The contraction of smooth muscles including airway smooth muscles is mediated by both Ca²+-dependent and Ca²+-independent pathways. The latter Ca²+-independent pathway, termed Ca²+ sensitization, is mainly regulated by a monomeric GTP-binding protein, RhoA, and its downstream target Rho-kinase. In animal models of allergic bronchial asthma, an augmented agonist-induced, RhoA-mediated contraction of bronchial smooth muscle has been suggested. The RhoA/Rho-kinase signaling is now proposed as a novel target for the treatment of airway hyperresponsiveness in asthma. Herein, we will discuss the mechanism of development of bronchial smooth muscle hyperresponsiveness, one of the causes of the airway hyperresponsiveness, based on the recent studies using animal models of allergic bronchial asthma and/or cultured airway smooth muscle cells. The possibility of RhoA as a therapeutic target in asthma, especially airway hyperresponsiveness, will also be described.

SKI-II, an inhibitor of sphingosine kinase, ameliorates antigen-induced bronchial smooth muscle hyperresponsiveness, but not airway inflammation, in mice.

To determine if endogenously generated sphingosine-1-phosphate (S1P) is involved in the development of allergic bronchial asthma, the effects of systemic treatments with SKI-II, a specific inhibitor of sphingosine kinase, on antigen-induced bronchial smooth muscle (BSM) hyperresponsiveness and airway inflammation were examined in mice. Male BALB/c mice were actively sensitized with ovalbumin (OA) antigen and were repeatedly challenged with aerosolized antigen. Animals also received intraperitoneal injections with SKI-II (50 mg/kg) 1 h prior to each antigen challenge. The acetylcholine (ACh)-induced contraction of BSM isolated from the repeatedly antigen-challenged mice was significantly augmented, that is, BSM hyperresponsiveness, as compared with that from the control animals (P < 0.05). The BSM hyperresponsiveness induced by antigen exposure was ameliorated by the systemic treatment with SKI-II, whereas the treatments had no effect on BSM responsiveness to ACh in control animals. On the other hand, the systemic treatments with SKI-II had no effect on antigen-induced inflammatory signs, such as increase in cell counts in bronchoalveolar lavage fluids (BALFs) and change in airway histology; upregulation of BALF cytokines, such as interleukin-4 (IL-4) and IL-13; and elevation of total and OA-specific immunoglobulin E (IgE) in sera. These findings suggest that sphingosine kinase inhibitors such as SKI-II have an ability to prevent the development of BSM hyperresponsiveness, but not of allergic airway inflammation. The endogenously generated S1P might be one of the exacerbating factors for the airway hyperresponsiveness, one of the characteristic features of allergic bronchial asthma.

MicroRNAs and their therapeutic potential for human diseases: MiR-133a and bronchial smooth muscle hyperresponsiveness in asthma.

MicroRNAs (miRNAs) play important roles in normal and diseased cell functions. The small-GTPase RhoA is one of the key proteins of bronchial smooth muscle (BSM) contraction, and an upregulation of RhoA has been demonstrated in BSMs of experimental asthma. Although the mechanism of RhoA upregulation in the diseased BSMs is not fully understood, recent observations suggest that RhoA translation is controlled by a miRNA, miR-133a, in cardiomyocytes. Similarly, in human BSM cells (hBSMCs), our recent studies revealed that an upregulation of RhoA was induced when the function of endogenous miR-133a was inhibited by its antagomir. Treatment of hBSMCs with interleukin-13 (IL-13) caused an upregulation of RhoA and a downregulation of miR-133a. In a mouse model of allergic bronchial asthma, increased expression of IL-13 and RhoA and the BSM hyperresponsiveness were observed. The level of miR-133a was significantly decreased in BSMs of the diseased animals. These findings suggest that RhoA expression is negatively regulated by miR-133a in BSMs and that the miR-133a downregulation causes an upregulation of RhoA, resulting in an augmentation of the contraction. MiR-133a might be a key regulator of BSM hyperresponsiveness and provide us with new insight into the treatment of airway hyperresponsiveness in asthmatics.

Induction of RhoA gene expression by interleukin-4 in cultured human bronchial smooth muscle cells.

RhoA, a small GTPase, is one of the key proteins of smooth muscle contraction. In allergic asthma, an upregulation of RhoA in bronchial smooth muscle has been suggested. However, the mechanism of its upregulation has not yet been clarified. In the present study, the effects of interleukin-4 (IL-4), one of the T-helper 2 cytokines, on RhoA mRNA expression and promoter activity of RhoA gene were examined in cultured human bronchial smooth muscle cells (hBSMCs). The quantitative real-time RT-PCR analyses revealed that incubation of hBSMCs with IL-4 (10, 30 and 100 ng/mL, for 24 hr) caused an increase in RhoA mRNA in a concentration-dependent manner. In luciferase reporter gene assay using hBSMCs that were transfected with luciferase constructs and were then stimulated with IL-4 (100 ng/mL), an importance of the most proximal STAT6 binding region (78-70 bp upstream of the transcription initiation site) was suggested. It is thus possible that IL-4 is capable of upregulating RhoA by promoting its transcription in hBSMCs. The proximal STAT6 binding region is required for the IL-4-induced increase in promoter activity of the human RhoA gene.