Pulmonary hypertension (PH) encompasses a diverse group of diseases marked by vascular injury and increased pulmonary artery pressures. Many sub-phenotypes of PH share a common link to the metabolic syndrome (systemic hypertension, obesity, glucose intolerance). For example, obesity, hyperlipidemia, and systemic hypertension are common risk factors for Group I pulmonary arterial hypertension (PAH) as well as for a subset of Group II (PH-heart failure with preserved ejection fraction, HF-pEF). The microbiome is important in development of obesity and the metabolic syndrome and is altered by high fat diet (HFD), suggesting that it may also play a role in PH. In Phase I of the tPPG, we tested 36 mouse strains and discovered that a 60% HFD led to PH HF-pEF, but only in certain strains. In our preliminary data, mice that developed PH on HFD had an increased ratio of gut Firmicutes to Bacteroidetes, similar to changes in obese humans with metabolic syndrome. In contrast, mice that did not develop PH on a high fat diet had a stable ratio. When commensal bacteria were decreased by treating mice with broad-spectrum antibiotics during HFD, the Firmicutes to Bacteroidetes ratio increased further, and manifestations of PH worsened. Despite a growing literature implicating the microbiome in a wide range of diseases, these studies are the first to support a critical protective role of bacteria in PH. Oral bacteria are also crucial, given that they are required for enterosalivary conversion of dietary nitrate to nitrite. Lack of these bacteria could result in decreased nitrite availability and resultant loss of downstream reactions in the host such as generation of nitric oxide and lipid signaling mediators such as electrophilic nitro-fatty acid (NO2-FA), leading to vasoconstriction and vascular proliferation. Abolishing oral microbes leads to systemic hypertension, but effects on the pulmonary vasculature are unknown. Thus, the goal of Project 3 is to define the relationships between PH, high fat diet, the oral and gut microbiome, and the metabolism of nitrogen oxide signaling mediators that may regulate the development and severity of PH. Our overall hypothesis is that the commensal microbiome is beneficial in PH because of its function in bioactivation of the nitrate-nitrite-NO-NO2-FA pathway. This hypothesis will be tested in murine models and in PH patients with the following specific aims:
Aim 1. Bench To test the hypothesis that bacteria are essential for nitrate (NO3-) reduction and NOx metabolism in animal models of PH.
Aim 2. Bedside To determine epidemiological relationships of oral and gut microbial structure and function to PH in humans and test the specific hypothesis that the oral microbiome is critical for protective nitrate bioactivation and improves pulmonary hemodynamics. Successful completion will profoundly shift the current paradigm of PH and yield novel avenues for therapy. This innovative proposal will leverage resources established during Phase I of the tPPG and is highly synergistic with all Projects and Cores.

Public Health Relevance

Pulmonary hypertension is a disease with a variety of causes and variable phenotypes. Although the role of the microbiome has been explored in many chronic diseases such as cardiovascular disease, obesity, and asthma, no studies have examined the role the microbiome in the development of pulmonary hypertension. Our preliminary data indicate that microbial communities present in the mouth or gut could play an important role in pulmonary hypertension pathogenesis. By exploring the impact of the microbiome, genetics, and diet in both mice and humans, this project could lead to discovery of novel therapeutics to treat and prevent pulmonary hypertension.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Program Projects (P01)
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Special Emphasis Panel (ZHL1)
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University of Pittsburgh
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Freeman, Bruce A; O'Donnell, Valerie B; Schopfer, Francisco J (2018) The discovery of nitro-fatty acids as products of metabolic and inflammatory reactions and mediators of adaptive cell signaling. Nitric Oxide 77:106-111
Villacorta, Luis; Minarrieta, Lucia; Salvatore, Sonia R et al. (2018) In situ generation, metabolism and immunomodulatory signaling actions of nitro-conjugated linoleic acid in a murine model of inflammation. Redox Biol 15:522-531
Remy, Kenneth E; Cort├ęs-Puch, Irene; Solomon, Steven B et al. (2018) Haptoglobin improves shock, lung injury, and survival in canine pneumonia. JCI Insight 3:
Rom, Oren; Khoo, Nicholas K H; Chen, Y Eugene et al. (2018) Inflammatory signaling and metabolic regulation by nitro-fatty acids. Nitric Oxide :
D'Amore, Antonio; Fazzari, Marco; Jiang, Hong-Bin et al. (2018) Nitro-Oleic Acid (NO2-OA) Release Enhances Regional Angiogenesis in a Rat Abdominal Wall Defect Model. Tissue Eng Part A 24:889-904
Schopfer, Francisco J; Vitturi, Dario A; Jorkasky, Diane K et al. (2018) Nitro-fatty acids: New drug candidates for chronic inflammatory and fibrotic diseases. Nitric Oxide 79:31-37
Farkas, Daniela; Thompson, A A Roger; Bhagwani, Aneel R et al. (2018) Toll-like Receptor 3 is a Therapeutic Target for Pulmonary Hypertension. Am J Respir Crit Care Med :
Goncharov, Dmitry A; Goncharova, Elena A; Tofovic, Stevan P et al. (2018) Metformin Therapy for Pulmonary Hypertension Associated with Heart Failure with Preserved Ejection Fraction versus Pulmonary Arterial Hypertension. Am J Respir Crit Care Med 198:681-684
Rafikova, Olga; Williams, Elissa R; McBride, Matthew L et al. (2018) Hemolysis-induced Lung Vascular Leakage Contributes to the Development of Pulmonary Hypertension. Am J Respir Cell Mol Biol 59:334-345
Hensley, Matthew K; Levine, Andrea; Gladwin, Mark T et al. (2018) Emerging therapeutics in pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 314:L769-L781

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