Seihai-to (TJ-90)-Induced Activation of Airway Ciliary Beatings of Mice: Ca2+ Modulation of cAMP-Stimulated Ciliary Beatings via PDE1.

Sei-hai-to (TJ-90, Qing Fei Tang), a Chinese traditional medicine, increases ciliary beat frequency (CBF) and ciliary bend angle (CBA) mediated via cAMP (3',5'-cyclic adenosine monophosphate) accumulation modulated by Ca2+-activated phosphodiesterase 1 (PDE1A). A high concentration of TJ-90 (≥40 µg/mL) induced two types of CBF increases, a transient increase (an initial increase, followed by a decrease) and a sustained increase without any decline, while it only sustained the CBA increase. Upon inhibiting increases in intracellular Ca2+ concentration ([Ca2+]i) by 10 µM BAPTA-AM (Ca2+-chelator, 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) or Ca2+/calmodulin-dependent PDE1 by 8MmIBMX (a selective PDE1 inhibitor), TJ-90 (400 µg/mL) induced only the sustained CBF increase without any transient CBF increase. The two types of the CBF increase (the transient increase and the sustained increase) induced by TJ-90 (≥40 µg/mL) were mimicked by the stimulation with both procaterol (100 pM) and ionomycin (500 nM). Thus, TJ-90 stimulates small increases in the intracellular cAMP concentration ([cAMP]i) and [Ca2+]i in airway ciliary cells of mice. These small increases in [cAMP]i and [Ca2+]i cause inducing a transient CBF increase or a sustained CBF increase in an airway ciliary cells, depending on the dominant signal, Ca2+-signal, or cAMP-signal.

Dietary antioxidants prevent alcohol-induced ciliary dysfunction.

Previously we have shown that chronic alcohol intake causes alcohol-induced ciliary dysfunction (AICD), leading to non-responsive airway cilia. AICD likely occurs through the downregulation of nitric oxide (NO) and cyclic nucleotide-dependent kinases, protein kinase G (PKG) and protein kinase A (PKA). Studies by others have shown that dietary supplementation with the antioxidants N-acetylcysteine (NAC) and procysteine prevent other alcohol-induced lung complications. This led us to hypothesize that dietary supplementation with NAC or procysteine prevents AICD. To test this hypothesis, C57BL/6 mice drank an alcohol/water solution (20% w/v) ad libitum for 6 weeks and were concurrently fed dietary supplements of either NAC or procysteine. Ciliary beat frequency (CBF) was measured in mice tracheas, and PKG/PKA responsiveness to ß-agonists and NOx levels were measured from bronchoalveolar lavage (BAL) fluid. Long-term alcohol drinking reduced CBF, PKG and PKA responsiveness to ß-agonists, and lung NOx levels in BAL fluid. In contrast, alcohol-drinking mice fed NAC or procysteine sustained ciliary function and PKG and PKA responsiveness to ß-agonists. However, BAL NO levels remained low despite antioxidant supplementation. We also determined that removal of alcohol from the drinking water for as little as 1 week restored ciliary function, but not PKG and PKA responsiveness to ß-agonists. We conclude that dietary supplementation with NAC or procysteine protects against AICD. In addition, alcohol removal for 1 week restores cilia function independent of PKG and PKA activity. Our findings provide a rationale for the use of antioxidants to prevent damage to airway mucociliary functions in chronic alcohol-drinking individuals.

Treatment responses of procaterol and CD38 inhibitors in an ozone-induced airway hyperresponsiveness mice model.

Airway hyperresponsiveness (AHR) and airway inflammation are key pathophysiological features of many respiratory diseases, such as asthma and chronic obstructive pulmonary disease (COPD). To evaluate the treatment responses of procaterol and CD38 inhibitors in an ozone-induced AHR mice model, we hypothesized that procaterol and two synthetic CD38 inhibitors (Compounds T and H) might have therapeutic effects on the ozone-induced AHR mice model, and the nuclear factor-kappaB (NF-κB) pathway and the CD38 enzymatic activity might be involved in the mechanisms. With the exception of the Control group, ozone exposure was used to establish an AHR model. Male Kunming mice in the Procaterol and CD38 inhibitors groups were treated with an emulsifier of procaterol hydrochloride, Compound T or H. Results indicated that (1) no drug showed severe toxicity in this study; (2) ozone exposure induced airway inflammation and AHR; (3) intragastric treatment with procaterol and Compound T achieved potent therapeutic effects, but Compound H did not show any therapeutic effect; (4) the NF-κB pathway was involved in both the pathogenic mechanisms of ozone and therapeutic mechanisms of procaterol and Compound T; (5) however, the in vivo effect of Compound T was not caused by its inhibitory activity on CD38. Taken together, procaterol and Compound T are potentially good drugs to treat asthma and COPD complicated with ozone exposure.

Effects of KP-496, a novel dual antagonist for leukotriene D4 and thromboxane A2 receptors, on contractions induced by various agonists in the guinea pig trachea.

BACKGROUND: A dry powder inhaler of KP-496 is currently in clinical development in Japan as an anti-asthmatic agent. The aim of this study was to evaluate the in vitro pharmacological profile of KP-496. METHODS: The antagonistic activities of KP-496 for leukotriene (LT) D(4) and thromboxane (TX) A(2) receptors were examined using the LTD(4)- and U46619-induced contractions of the isolated guinea pig trachea. The selectivity of KP-496 was examined using various agonist-induced contractions in the isolated guinea pig trachea. RESULTS: KP-496 produced parallel rightward shifts of the LTD(4) and U46619 concentration-response curves in a concentration-dependent manner. Schild plot analyses of the antagonistic activities of KP-496 demonstrated that it is a competitive antagonist for LTD(4) and TXA(2) receptors with pA(2) values of 8.64 and 8.23, respectively. The LTD(4) antagonistic activity of KP-496 was comparable to that of pranlukast and zafirlukast but was more potent than that of montelukast. The TXA(2) antagonistic activity of KP-496 was comparable to that of seratrodast. KP-496 and seratrodast also inhibited the prostaglandin (PG) D(2)- and PGF(2alpha)-induced contractions of the isolated guinea pig trachea. KP-496 had no effect on the histamine-, acetylcholine-, serotonin- and substance P-induced contractions of the isolated guinea pig trachea. CONCLUSIONS: These results indicate that KP-496 is a selective dual antagonist for LTD(4) and TXA(2) receptors. LTD(4) and TXA(2) play important roles in asthma, and antagonists for these mediators are being used for the treatment of asthma. Thus, KP-496 is expected to become a novel potent therapeutic agent for asthma.

beta(2)-adrenergic receptor overexpression increases alveolar fluid clearance and responsiveness to endogenous catecholamines in rats.

beta-Adrenergic agonists accelerate the clearance of alveolar fluid by increasing the expression and activity of epithelial solute transport proteins such as amiloride-sensitive epithelial Na(+) channels (ENaC) and Na,K-ATPases. Here we report that adenoviral-mediated overexpression of a human beta(2)-adrenergic receptor (beta(2)AR) cDNA increases beta(2)AR mRNA, membrane-bound receptor protein expression, and receptor function (procaterol-induced cAMP production) in human lung epithelial cells (A549). Receptor overexpression was associated with increased catecholamine (procaterol)-responsive active Na(+) transport and increased abundance of Na,K-ATPases in the basolateral cell membrane. beta(2)AR gene transfer to the alveolar epithelium of normal rats improved membrane-bound beta(2)AR expression and function and increased levels of ENaC (alpha subunit) abundance and Na,K-ATPases activity in apical and basolateral cell membrane fractions isolated from the peripheral lung, respectively. Alveolar fluid clearance (AFC), an index of active Na(+) transport, in beta(2)AR overexpressing rats was up to 100% greater than sham-infected controls and rats infected with an adenovirus that expresses no cDNA. The addition of the beta(2)AR-specific agonist procaterol to beta(2)AR overexpressing lungs did not increase AFC further. AFC in beta(2)AR overexpressing lungs from adrenalectomized or propranolol-treated rats revealed clearance rates that were the same or less than normal, untreated, sham-infected controls. These experiments indicate that alveolar beta(2)AR overexpression improves beta(2)AR function and maximally upregulates beta-agonist-responsive active Na(+) transport by improving responsiveness to endogenous catecholamines. These studies suggest that upregulation of beta(2)AR function may someday prove useful for the treatment of pulmonary edema.