Supplementation with the Postbiotic BPL1™-HT (Heat-Inactivated Bifidobacterium animalis subsp. Lactis) Attenuates the Cardiovascular Alterations Induced by Angiotensin II Infusion in Mice

Abstract

Hypertension is associated with alterations in the composition and diversity of the intestinal microbiota. Indeed, supplementation with probiotics and prebiotics has shown promising results in modulating the gut microbiota and improving cardiovascular health. However, there are no studies regarding the possible beneficial effects of postbiotics on cardiovascular function and particularly on hypertension-induced cardiovascular alterations. Thus, the aim of this study was to analyze the effect of supplementation with the heat-treated Bifidobacterium animalis subsp. lactis CECT 8145 strain (BPL1™ HT), a postbiotic developed by the company ADM-Biopolis, on cardiovascular alterations induced by angiotensin II (AngII) infusion in mice. For this purpose, three groups of C57BL/6J male mice were used: (i) mice infused with saline (control); (ii) mice infused with AngII for 4 weeks (AngII); and (iii) mice supplemented with BPL1™ HT in the drinking water (1010 cells/animal/day) for 8 weeks and infused with AngII for the last 4 weeks (AngII + BPL1™ HT). AngII infusion was associated with heart hypertrophy, hypertension, endothelial dysfunction, and overexpression of proinflammatory cytokines in aortic tissue. BPL1™ HT supplementation reduced systolic blood pressure and attenuated AngII-induced endothelial dysfunction in aortic segments. Moreover, mice supplemented with BPL1™ HT showed a decreased gene expression of the proinflammatory cytokine interleukin 6 (Il-6) and the prooxidant enzymes NADPH oxidases 1 (Nox-1) and 4 (Nox-4), as well as an overexpression of AngII receptor 2 (At2r) and interleukin 10 (Il-10) in arterial tissue. In the heart, BPL1™ HT supplementation increased myocardial contractility and prevented ischemia-reperfusion-induced cardiomyocyte apoptosis. In conclusion, supplementation with the postbiotic BPL1™ HT prevents endothelial dysfunction, lowers blood pressure, and has cardioprotective effects in an experimental model of hypertension induced by AngII infusion in mice.

Keywords: angiotensin II; antioxidant; cardiovascular damage; hypertension; inflammation; postbiotic.

Figure 1

Systolic blood pressure (A) and body weight gain (B) in mice infused with saline (control), mice infused with AngII (AngII), and mice infused with AngII and supplemented with HTBPL-1 (AngII + HTBPL1). Values are represented as mean value ± SEM; n = 7–8 mice/group. ** p < 0.01 vs. control; *** p < 0.001 vs. control; # p < 0.001 vs. AngII.

Figure 2

Relaxation of thoracic aortic segments to sodium nitroprusside (NTP) (10⁻⁹–10⁻⁵ M) (A) and to acetylcholine (ACh) (10⁻⁹–10⁻⁴ M) (B); Emax relaxation to acetylcholine in the presence/absence of apocynin (ACh/ACh + Apo) (10⁻⁶ M) (C) of mice infused with saline (control), mice infused with AngII (AngII), and mice infused with AngII and supplemented with BPL1™ HT (AngII + BPL1™ HT). One aortic ring from each mouse was used for each condition (n = 7–8 samples/group). Values are represented as mean value ± SEM;. * p < 0.05 vs. control; ** p < 0.01 vs. control; # p < 0.05 vs. AngII; $ p < 0.05 vs. Ach of its experimental group.

Figure 3

Thickness of the tunica media (A) and representative images of aorta sections stained with hematoxylin–eosin (B). The scale bar is equivalent to 150 μm. Gene expression of monocyte chemotactic protein-1 (Mcp-1), interleukin-1β (Il-1β), interleukin-6 (Il-6), interleukin-10 (Il-10), and tumor necrosis factor α (Tnf-α) (C) in mice aorta infused with saline (control), infused with AngII (AngII), and infused with AngII and supplemented with BPL1™ HT (AngII + BPL1™ HT). Data are represented as mean value ± SEM; n = 7–8 mice/group. For the assessment of tunica media thickness, four sections of four different mice from each experimental group were used. * p < 0.05 vs. control; ** p < 0.05 vs. control; # p < 0.05 vs. AngII.

Figure 4

Quantification of reactive oxygen species (A) and representative images of aorta sections stained with dihydroethidium (B). The scale bar is equivalent to 100 μm. Gene expression of NADPH oxidase 1 (Nox-1), NADPH oxidase 4 (Nox-4), super oxide dismutase 1 (Sod-1), glutathione peroxidase 3 (Gpx-3), glutathione reductase (Gsr), and hemoxigenase 1 (Ho-1) (C) in aorta of mice infused with saline (control), mice infused with AngII (AngII), and mice infused with AngII and supplemented with BPL1™ HT (AngII + BPL1™ HT). Values are represented as the mean ± S.E.M (n = 7–8 mice/experimental group). For the DHE staining, four sections of four different mice from each experimental group were used. * p < 0.05 vs. control; ** p < 0.01 vs. control; *** p < 0.001 vs. control; # p < 0.05 vs. AngII.

Figure 5

Heart contractility measured before and after ischemia–reperfusion (A), quantification of cardiomyocyte apoptosis in ischemic hearts analyzed by TUNEL assay, and representative images of heart sections stained with TUNEL staining; (B) protein content of Caspase 8 (C) in ischemic hearts of mice infused with saline (control), mice infused with AngII (AngII), and mice infused with AngII and supplemented with BPL1™ HT (AngII + BPL1™ HT). Values are represented as the mean ± S.E.M (n = 7–8 mice/group). The scale bar is equivalent to 100 μm. For the analysis of Caspase 8 protein content, 3–4 samples per experimental group were used. * p < 0.05 vs. control; # p < 0.05 vs. AngII; ## p < 0.01 vs. AngII.

Figure 6

Gene expression of monocyte chemotactic protein-1 (Mcp-1), interleukin-1β (Il-1β), interleukin-6 (Il-6), interleukin-10 (Il-10), and tumor necrosis factor α (Tnf-α) (A); gene expression of NADPH oxidase 1 (Nox-1), NADPH oxidase 4 (Nox-4), super oxide dismutase 1 (Sod-1), glutathione peroxidase 3 (Gpx-3), glutathione reductase (Gsr), and hemoxigenase 1 (Ho-1) (B) in the heart of mice infused with saline (control), mice infused with AngII (AngII), and mice infused with AngII and supplemented with BPL1™ HT (AngII + BPL1™ HT). The values are represented as the mean ± S.E.M (n = 7–8 samples/experimental group by duplicate) and expressed as a percentage vs. control; * p < 0.05 vs. control; # p < 0.05 vs. AngII.

Figure 7

Plasma levels of angiotensin-(1–7) (A) and gene expression of angiotensin converting enzyme 2 (ACE2), angiotensin II receptor type 1 (At1r), and angiotensin II receptor type 2 (At2r) in the aorta (B) and in the heart (C) of mice infused with saline (control), mice infused with AngII (AngII), and mice infused with AngII and supplemented with BPL1™ HT (AngII + BPL1™ HT). The values are represented as the mean ± S.E.M (n = 7–8 samples/experimental group) and expressed as a percentage vs. control; * p < 0.05 vs. control; ** p < 0.01 vs. control; # p < 0.05 vs. AngII.

Figure 8

Malondialdehyde (MDA) plasma levels measured by high-performance liquid chromatography (HPLC) of mice infused with saline (control), mice infused with AngII (AngII), and mice infused with AngII and supplemented with BPL1™ HT (AngII + BPL1™ HT). The values are represented as the mean ± S.E.M (n = 7–8 samples/experimental group). * p < 0.05 vs. control.