An arginase-1 SNP that protects against the development of pulmonary hypertension in bronchopulmonary dysplasia enhances NO-mediated apoptosis in lymphocytes.

Jennifer K Trittmann,Louis G Chicoine,Bernadette Chen,Yi Jin,Leif D Nelin,Yusen Liu

doi:10.14814/phy2.13041

Jennifer K Trittmann, Louis G Chicoine + Show 4 more

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https://doi.org/10.14814/phy2.13041

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Journal: Physiological Reports	Publication Date: Nov 1, 2016
Citations: 14	License type: cc-by

Affiliation: The Ohio State University

Abstract

Arginase and nitric oxide synthase (NOS) share a common substrate, l‐arginine, and have opposing effects on vascular remodeling. Arginase is the first step in polyamine and proline synthesis necessary for cellular proliferation, while NO produced from NOS promotes apoptosis. Previously, we identified a single nucleotide polymorphism (SNP) in the arginase‐1 (ARG1) gene, rs2781666 (T‐allele) that was associated with a decreased risk for developing pulmonary hypertension (PH) in a cohort of infants with bronchopulmonary dysplasia (BPD). In this study, we utilized lymphocytes from neonates (the only readily available cells from these patients expressing the two genotypes of interest) with either the rs2781666 SNP (TT) or wild type (GG) to test the hypothesis that the protection of the ARG1 SNP against the development of PH in BPD would involve augmented NO production leading to more apoptosis. Lymphocytes were stimulated with IL‐4, IL‐13, and phorbol myristate acetate (PMA). We found that TT lymphocytes had similar levels of arginase I and arginase II expression, but there was a tendency for lower urea production (a surrogate marker of arginase activity), than in the GG lymphocytes. The TT lymphocytes also had significantly greater NO production than did GG lymphocytes despite no differences in iNOS expression between genotypes. Furthermore, the TT lymphocytes had lower numbers of viable cells, and higher levels of cleaved caspase‐3 than did GG lymphocytes. Inhibiting NOS activity using N ω‐Nitro‐l‐arginine methyl ester hydrochloride (l‐NAME) significantly decreased cleaved caspase‐3 levels in the TT lymphocytes. These data demonstrate that the TT genotype results in greater levels of NO production leading to more apoptosis, which is consistent with the concept that BPD patients with the TT genotype are protected against the development of PH by producing greater basal levels of endogenous NO.

Highlights

Bronchopulmonary dysplasia (BPD) is seen primarily in extremely preterm neonates who require positive pressure ventilation and supplemental oxygen in order to survive
We found that one single nucleotide polymorphism (SNP), a G to T substitution at position 4195 in the ARG1 gene (ARG1 rs2781666 SNP), was less frequent in patients with BPD and pulmonary hypertension (PH) than in patients with BPD alone, and for each copy of the SNP minor allele (T), the odds of developing PH decreased by 43% (Trittmann et al 2014)
The main findings of this study were that lymphocytes from patients homozygous for the ARG1 rs2781666 SNP (TT) compared to lymphocytes from patients with the GG genotype had: (1) similar expression levels of arginase I, arginase II, there was a tendency toward lower urea production; (2) greater Nitric oxide (NO) production the expression levels of iNOS were similar; (3) less cellular proliferation; and (4) greater levels of cleaved caspase-3 and the levels of cleaved caspase-3 were significantly attenuated by NO synthase (NOS) inhibition

Summary

Introduction

Bronchopulmonary dysplasia (BPD) is seen primarily in extremely preterm neonates who require positive pressure ventilation and supplemental oxygen in order to survive. These therapies can result in disruption of normal lung development leading to BPD and BPD-associated pulmonary hypertension (PH) (Baker et al 2014). Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

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