A slippery cause of a slimy problem: Mucin induction by an esterified lipid

Secreted gel-forming mucins (1) are key components of mucociliary transport, a vital airway innate defense mechanism (2). Mucin and mucus alterations are present in asthma (3), cystic fibrosis (4), and chronic bronchitis (5), and mucin gene polymorphisms are also implicated in the pathogenesis of idiopathic pulmonary fibrosis (6). Increased numbers of mucin-producing goblet cells at locations where they are normally present (hyperplasia) or absent (metaplasia) are pathognomonic responses of the airways to diverse environmental stimuli. Although they are clearly important and protective at homeostatic levels, mucin and mucus are likely harmful when produced in excess, as most vividly and tragically illustrated in fatal asthma (Figure 1). Importantly, specific therapies targeting mucin hypersecretion in asthma and other lung pathologies are not currently available

Implementing machine learning methods with complex survey data: Lessons learned on the impacts of accounting sampling weights in gradient boosting

Despite the prominent use of complex survey data and the growing popularity of machine learning methods in epidemiologic research, few machine learning software implementations offer options for handling complex samples. A major challenge impeding the broader incorporation of machine learning into epidemiologic research is incomplete guidance for analyzing complex survey data, including the importance of sampling weights for valid prediction in target populations. Using data from 15, 820 participants in the 1988-1994 National Health and Nutrition Examination Survey cohort, we determined whether ignoring weights in gradient boosting models of all-cause mortality affected prediction, as measured by the F1 score and corresponding 95% confidence intervals. In simulations, we additionally assessed the impact of sample size, weight variability, predictor strength, and model dimensionality. In the National Health and Nutrition Examination Survey data, unweighted model performance was inflated compared to the weighted model (F1 score 81.9% [95% confidence interval: 81.2%, 82.7%] vs 77.4% [95% confidence interval: 76.1%, 78.6%]). However, the error was mitigated if the F1 score was subsequently recalculated with observed outcomes from the weighted dataset (F1: 77.0%; 95% confidence interval: 75.7%, 78.4%). In simulations, this finding held in the largest sample size (N = 10,000) under all analytic conditions assessed. For sample sizes <5,000, sampling weights had little impact in simulations that more closely resembled a simple random sample (low weight variability) or in models with strong predictors, but findings were inconsistent under other analytic scenarios. Failing to account for sampling weights in gradient boosting models may limit generalizability for data from complex surveys, dependent on sample size and other analytic properties. In the absence of software for configuring weighted algorithms, post-hoc re-calculations of unweighted model performance using weighted observed outcomes may more accurately reflect model prediction in target populations than ignoring weights entirely

High salt diet exacerbates vascular contraction in the absence of adenosine A2A receptor

High salt (4% NaCl, HS) diet modulates adenosine-induced vascular response through adenosine A2A receptor (A2AAR). Evidence suggests that A2AAR stimulates cyp450-epoxygenases, leading to epoxyeicosatrienoic acids (EETs) generation. The aim of this study was to understand the vascular reactivity to HS and underlying signaling mechanism in the presence or absence of A2AAR. Therefore, we hypothesized that HS enhances adenosine-induced relaxation through EETs in A2AAR, but exaggerates contraction in A2AAR. Organ bath and Western blot experiments were conducted in HS and normal salt (NS, 0.18% NaCl)-fed A2AAR and A2AAR mice aorta. HS produced concentration-dependent relaxation to non-selective adenosine analog, NECA in A2AAR, whereas contraction was observed in A2AAR mice and this was attenuated by A1AR antagonist (DPCPX). CGS 21680 (selective A2AAR agonist) enhanced relaxation in HS-A2AAR versus NS-A2AAR, which was blocked by EETs antagonist (14,15-EEZE). Compared with NS, HS significantly upregulated the expression of vasodilators A2AAR and cyp2c29, whereas vasoconstrictors A1AR and cyp4a in A2AAR were downregulated. In A2AAR mice, however, HS significantly downregulated the expression of cyp2c29, whereas A1AR and cyp4a were upregulated compared with A2AAR mice. Hence, our data suggest that in A2AAR, HS enhances A2AAR-induced relaxation through increased cyp-expoxygenases-derived EETs and decreased A1AR levels, whereas in A2AAR, HS exaggerates contraction through decreased cyp-epoxygenases and increased A1AR levels. Copyright ?2013 by Lippincott Williams & Wilkins.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Role of Müller cell cytochrome P450 2c44 in murine retinal angiogenesis

Polyunsaturated fatty acids (PUFA) and their cytochrome P450 (CYP450) metabolites have been linked to angiogenesis and vessel homeostasis. However, the role of individual CYP isoforms and their endogenous metabolites in those processes are not clear. Here, we focused on the role of Cyp2c44 in postnatal retinal angiogenesis and report that Cyp2c44 is highly expressed in Müller glial cells in the retina. The constitutive as well as inducible postnatal genetic deletion of Cyp2c44 resulted in an increased vessel network density without affecting vessel radial expansion during the first postnatal week. This phenotype was associated with an increased endothelial cell proliferation and attenuated Notch signaling. LC-MS/MS analyses revealed that levels of hydroxydocosahexaenoic acids (HDHA), i.e., 10-, 17- and 20-HDHA were significantly elevated in retinas from 5day old Cyp2c44(-/-) mice compared to their wild-type littermates. Enzymatic activity assays revealed that HDHAs were potential substrates for Cyp2c44 which could account for the increased levels of HDHAs in retinas from Cyp2c44(-/-) mice. These data indicate that Cyp2c44 is expressed in the murine retina and, like the soluble epoxide hydrolase, is expressed in Müller glia cells. The enhanced endothelial cell proliferation and Notch inhibition seen in retinas from Cyp2c44-deficient mice indicate a role for Cyp2c44-derived lipid mediators in physiological angiogenesis

Role of ω-hydroxylase in adenosine-mediated aortic response through MAP kinase using a 2A-receptor knockout mice

Previously, we have shown that A 2A adenosine receptor (A 2AAR) knockout mice (KO) have increased contraction to adenosine. The signaling mechanism(s) for A 2AAR is still not fully understood. In this study, we hypothesize that, in the absence of A 2AAR, ω-hydroxylase (Cyp4a) induces vasoconstriction through mitogen-activated protein kinase (MAPK) via upregulation of adenosine A1 receptor (A 1AR) and protein kinase C (PKC). Organ bath and Western blot experiments were done using isolated aorta from A 2AKO and corresponding wild-type (WT) mice. Isolated aortic rings from WT and A2AKO mice were precontracted with submaximal dose of phenylephrine (10 -6 M), and concentration responses for selective A 1AR, A 2AAR agonists, angiotensin II and cytochrome P-450-epoxygenase, 20-hydroxyeicosatrienoic acid (20- HETE) PKC, PKC-α, and ERK1/2 inhibitors were obtained. 2-p-(2- Carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680, A 2AAR agonist) induced concentration-dependent relaxation in WT, which was blocked by methylsulfonyl-propargyloxyphenylhexanamide (cytochrome P-450-epoxygenase inhibitor; 10 -5 M) and also with removal of endothelium. A 1 agonist, 2-chloro-N 6- cyclopentyladenosine (CCPA) produced higher contraction in A 2AKO aorta than WT (49.2 ± 8.5 vs. 27 ± 5.9% at 10 -6 M, P < 0.05). 20-HETE produced higher contraction in A 2AKO than WT (50.6 ± 8.8 vs. 21.1 ± 3.3% at 10 -7 M, P < 0.05). Contraction to CCPA in WT and A 2AKO aorta was inhibited by PD-98059 (p42/p44 MAPK inhibitor; 10 -6 M), chelerythrine chloride (nonselective PKC blocker; 10 -6 M), Gö-6976 (selective PKC-α inhibitor; 10 -7 M), and HET0016 (20-HETE inhibitor; 10 -5 M). Also, contraction to 20- HETE in WT and A 2AKO aorta was inhibited by PD-98059 and Gö-6976. Western blot analysis indicated the upregulation of A 1AR, Cyp4a, PKC-α, and phosphorylated-ERK1/2 in A 2AKO compared with WT (P < 0.05), while expression of Cyp2c29 was significantly higher in WT. CCPA (10 -6 M) increased the protein expression of PKC-α and phosphorylated-ERK1/2, while HET0016 significantly reduced the CCPA-induced increase in expression of these proteins. These data suggest that, in the absence of A 2AAR, Cyp4a induces vasoconstriction through MAPK via upregulation of A 1AR and PKC-α. © 2012 the American Physiological Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Reduced coronary reactive hyperemia in mice was reversed by the soluble epoxide hydrolase inhibitor (t-AUCB): Role of adenosine A2A receptor and plasma oxylipins

Coronary reactive hyperemia (CRH) protects the heart against ischemia. Adenosine A2AAR–deficient (A2AAR−/−) mice have increased expression of soluble epoxide hydrolase (sEH); the enzyme responsible for breaking down the cardioprotective epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs). sEH–inhibition enhances CRH, increases EETs, and modulates oxylipin profiles. We investigated the changes of oxylipins and their impact on CRH in A2AAR−/− and wild type (WT) mice. We hypothesized that the attenuated CRH in A2AAR−/− mice is mediated by changes in oxylipin profiles, and that it can be reversed by either sEH- or ω-hydroxylases–inhibition. Compared to WT mice, A2AAR−/− mice had attenuated CRH and changed oxylipin profiles, which were consistent between plasma and heart perfusate samples, including decreased EET/DHET ratios, and increased hydroxyeicosatetraenoic acids (HETEs). Plasma oxylipns in A2AAR−/− mice indicated an increased proinflammatory state including increased ω-terminal HETEs, decreased epoxyoctadecaenoic/dihydroxyoctadecaenoic acids (EpOMEs/DiHOMEs) ratios, increased 9-hydroxyoctadecadienoic acid, and increased prostanoids. Inhibition of either sEH or ω-hydroxylases reversed the reduced CRH in A2AAR−/− mice. In WT and sEH−/− mice, blocking A2AAR decreased CRH. These data demonstrate that A2AAR–deletion was associated with changes in oxylipin profiles, which may contribute to the attenuated CRH. Also, inhibition of sEH and ω-hydroxylases reversed the reduction in CRH.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Mechanistic definition of the cardiovascular mPGES-1/COX-2/ADMA axis.

Cardiovascular side effects caused by non-steroidal anti-inflammatory drugs (NSAIDs), which all inhibit cyclooxygenase (COX)-2, have prevented development of new drugs that target prostaglandins to treat inflammation and cancer. Microsomal prostaglandin E synthase-1 (mPGES-1) inhibitors have efficacy in the NSAID arena but their cardiovascular safety is not known. Our previous work identified asymmetric dimethylarginine (ADMA), an inhibitor of endothelial nitric oxide synthase, as a potential biomarker of cardiovascular toxicity associated with blockade of COX-2. Here, we have used pharmacological tools and genetically modified mice to delineate mPGES-1 and COX-2 in the regulation of ADMA. Inhibition of COX-2 but not mPGES-1 deletion resulted in increased plasma ADMA levels. mPGES-1 deletion but not COX-2 inhibition resulted in increased plasma prostacyclin levels. These differences were explained by distinct compartmentalization of COX-2 and mPGES-1 in the kidney. Data from prostanoid synthase/receptor knockout mice showed that the COX-2/ADMA axis is controlled by prostacyclin receptors (IP and PPARβ/δ) and the inhibitory PGE2 receptor EP4, but not other PGE2 receptors. These data demonstrate that inhibition of mPGES-1 spares the renal COX-2/ADMA pathway and define mechanistically how COX-2 regulates ADMA