Does the Oral Microbiome Play a Role in Hypertensive Pregnancies?

Abstract

Chronic hypertension during gestation is associated with an increased risk of adverse pregnancy outcomes including pre-eclampsia, fetal growth restriction and preterm birth. Research into new chemotherapeutic regimes for the treatment of hypertension in pregnancy is limited due to concerns about fetal toxicity and teratogenicity, and new therapeutic avenues are being sought in alternative physiological pathways. Historically, generation of the vasodilator nitric oxide was believed to be solely from L -arginine by means of nitric oxide synthase enzymes. Recently, a novel pathway for the reduction of dietary inorganic nitrate to nitrite by the bacteria in the oral cavity and subsequently to vasodilatory nitric oxide within the body has been uncovered. Dietary nitrate is abundant in green leafy vegetables, including beetroot and spinach, and reduction of exogenous nitrate to nitrite by oral bacteria can increase nitric oxide in the vasculature, lessening hypertension. Supplements rich in nitrate may be an attractive choice for treatment due to fewer side effects than drugs that are currently used to treat hypertensive pregnancy disorders. Additionally, manipulation of the composition of the oral microbiota using pro- and prebiotics in tandem with additional dietary interventions to promote cardiovascular health during gestation may offer a safe and effective means of treating hypertensive pregnancy disorders including gestational hypertension and pre-eclampsia. The use of dietary inorganic nitrate as a supplement during pregnancy requires further exploration and large scale studies before it may be considered as part of a treatment regime. The aim of this article is to review the current evidence that oral microbiota plays a role in hypertensive pregnancies and whether it could be manipulated to improve patient outcomes.

Periodontitis, Blood Pressure, and the Risk and Control of Arterial Hypertension: Epidemiological, Clinical, and Pathophysiological Aspects—Review of the Literature and Clinical Trials

“…Interestingly, the potential role of oral microbiota dysbiosis in the pathogenesis of pregnancy hypertension and its complications has been suggested [ 31 ]. In a study by Pralhad et al, involving 200 pregnant women, the influence of periodontitis on the risk of pregnancy hypertension was analyzed.…”

Physiological Changes and Interactions Between Microbiome and the Host During Pregnancy

“…Moreover, high estrogen levels promote infection by Candida (Kumar et al, 2013;Fujiwara et al, 2017). Willmott and co-workers (2020) demonstrated that the composition of the oral microbiome accurately reflects the dietary content of nitrate and the healthy regulation of blood pressure (Willmott et al, 2020). Bacteria in the oral cavity, located primarily on the tongue's surface, reduce nitrate enzymatically, resulting in the presence of nitrite in the saliva, which is subsequently transformed in the stomach into nitric acid and then reduced to nitric oxide (NO).…”

“…Bacteria in the oral cavity, located primarily on the tongue’s surface, reduce nitrate enzymatically, resulting in the presence of nitrite in the saliva, which is subsequently transformed in the stomach into nitric acid and then reduced to nitric oxide (NO). This process is related to blood pressure in two different ways: the plasma level of nitrate is related inversely to blood pressure, and, at the same time, NO is a key signal molecule in connection with processes that regulate the circulatory system ( Willmott et al., 2020 ).…”

“…In research from Walker et al., ( 2018 ) it was indicated that The oral microbiome play an important role in the production of the nitric oxide (NO) through nitrate-nitrite-NO pathway. The oral microbiota is deficient in the NO enzymes responsible for yielding the catalyzed NO from L-arginine ( Qu et al., 2016 ; Willmott et al., 2020 ). According to Walker et al., ( 2018 ), the production of nitric oxide occurs in the human body by two methods: dependent and independent.…”

“…Furthermore, the microbiome in the human body produces NO in an independent way through fermentation depending on food intake by the consumption of nitrate (NO3 - ) and nitrite (NO2 - ). In addition, oral microbiota has a major role in cardiovascular system wellbeing and in the regulation of blood pressure, including in pregnancy ( Willmott et al., 2020 ). A case-control study in a tertiary facility in Ghana ( Darkwa et al., 2018 ) found that the level of serum nitric oxide rises rapidly during pregnancy and peaks during the third trimester of a healthy pregnancy.…”