Carla Nunes

The gut microbiota consists of trillions of microorganisms, mostly bacteria, which establish a symbiotic relationship with the host. The host provides a favourable environment and the essential nutrients for their proliferation, while the gut microbiota plays a key role in maintaining the host’s health. Therefore, imbalances in its composition, a state known as dysbiosis, can contribute to the onset or progression of various pathological conditions, including atherosclerosis. Atherosclerosis is a chronic, slow-progressing inflammatory disease characterised by the formation and potential rupture of atheromatous plaques in medium- and large-calibre arteries. It underlies major cardiovascular events, such as stroke and myocardial infarction, and remains a leading cause of global morbidity and mortality. The modulation of the gut microbiota using prebiotics, probiotics, and faecal microbiota transplantation (FMT) has emerged as a promising approach for preventing and managing atherosclerosis. Although numerous studies have explored these strategies, further research is needed to establish their efficacy and mechanisms. This review explores the pathophysiology of atherosclerosis, its main risk factors, and the interplay between the gut microbiota and atherosclerosis, with a particular focus on the mechanisms by which microbiota-targeted interventions, including prebiotics, probiotics, and FMT, may serve as therapeutic adjuvants in the prevention and treatment of atherosclerosis.

Nitric oxide (^•NO), a diffusible free radical, is an intercellular messenger, playing a crucial role in several key brain physiological processes, including in neurovascular coupling (NVC). In the brain, glutamatergic activation of the neuronal nitric oxide synthase (nNOS) enzyme constitutes its main synthesis pathway. However, when oxygen (O₂) supply is compromised, such as in stroke, ischemia, and aging, such ^•NO production pathway may be seriously impaired. In this context, evidence suggests that, as already observed in the gastric compartment, the reduction of nitrite by dietary compounds (such as ascorbate and polyphenols) or by specific enzymes may occur in the brain, constituting an important rescuing or complementary mechanism of ^•NO production. Here, using microsensors selective for ^•NO, we show that nitrite enhanced the ^•NO production in a concentration-dependent manner and in the presence of ascorbate evoked by N-methyl-D-aspartate (NMDA) and glutamate stimulation of rat hippocampal slices. Additionally, nitrite potentiated the ^•NO production induced by oxygen-glucose deprivation (OGD). Overall, these observations support the notion of a redox interaction of ascorbate with nitrite yielding ^•NO upon neuronal glutamatergic activation and given the critical role of NO as the direct mediator of neurovascular coupling may represents a key physiological mechanism by which ^•NO production for cerebral blood flow (CBF) responses to neuronal activation is sustained under hypoxic/acidic conditions in the brain.

In this review, we address the regulatory and toxic role of ^·NO along several pathways, from the gut to the brain. Initially, we address the role on ^·NO in the regulation of mitochondrial respiration with emphasis on the possible contribution to Parkinson’s disease via mechanisms that involve its interaction with a major dopamine metabolite, DOPAC. In parallel with initial discoveries of the inhibition of mitochondrial respiration by ^·NO, it became clear the potential for toxic ^·NO-mediated mechanisms involving the production of more reactive species and the post-translational modification of mitochondrial proteins. Accordingly, we have proposed a novel mechanism potentially leading to dopaminergic cell death, providing evidence that NO synergistically interact with DOPAC in promoting cell death via mechanisms that involve GSH depletion. The modulatory role of NO will be then briefly discussed as a master regulator on brain energy metabolism. The energy metabolism in the brain is central to the understanding of brain function and disease. The core role of ^·NO in the regulation of brain metabolism and vascular responses is further substantiated by discussing its role as a mediator of neurovascular coupling, the increase in local microvessels blood flow in response to spatially restricted increase of neuronal activity. The many facets of NO as intracellular and intercellular messenger, conveying information associated with its spatial and temporal concentration dynamics, involve not only the discussion of its reactions and potential targets on a defined biological environment but also the regulation of its synthesis by the family of nitric oxide synthases. More recently, a novel pathway, out of control of NOS, has been the subject of a great deal of controversy, the nitrate:nitrite:NO pathway, adding new perspectives to ^·NO biology. Thus, finally, this novel pathway will be addressed in connection with nitrate consumption in the diet and the beneficial effects of protein nitration by reactive nitrogen species.

Fragaria vesca L. (F. vesca), popularly known as wild strawberry, is a plant from the Rosaceae family, found in temperate and subtropical areas of the northern hemisphere. F. vesca leaves have been shown to have antiseptic, emollient, and dermatological protection properties, due to the presence of bioactive compounds, such as flavonoids, phenolic acids, ellagitannins, and proanthocyanidins. In this study, a F. vesca extract was obtained by an optimized extraction process, and was characterized by HPLC, ROS scavenging activity, cytotoxicity assays in HaCaT cells, and tyrosinase inhibitory activity determination. The most active extract was then incorporated in a hydrogel with hydroxyethylcellulose at 2% (w/w), which was characterized at the physicochemical, stability, cytotoxicity, and ROS scavenging activity levels to evaluate its quality, safety, and efficacy. In vivo studies, human repeat insult patch testing, and an assay to determine their antioxidant efficacy, were also performed. The results showed that the Fragaria vesca extracts had antioxidant activity and that the F. vesca extract-based hydrogel exhibited cutaneous compatibility, acceptability and antioxidant efficacy, being stable, and suitable for topical application.

The altered expression and subcellular distribution of tight junction (TJ) proteins, leading to a dysfunctional intestinal barrier, is a key mechanistic feature of inflammatory bowel disease (IBD). Therefore, increasing the integrity of the intestinal barrier by manipulating the TJ may constitute an innovative and effective therapeutic strategy in IBD. In this context, recent studies showed that dietary polyphenols are able to protect the intestinal TJ barrier integrity. Here, using a cellular model of intestinal inflammation, consisting of cytokine-stimulated HT-29 colon epithelial cells, we show that a polyphenolic extract obtained from Portuguese red wine (RWE) decreased the paracellular permeability across the cell monolayer compared with the control cells, even in the presence of pro-inflammatory cytokines. The beneficial effect of RWE was exerted at three complementary levels: (1) by promoting a significant increase of the mRNA of key barrier-forming TJ proteins, including occludin, claudin-5 and zonnula occludens (ZO)-1 above the levels observed in the control cells; (2) by preventing the decrease in the expression of these proteins under inflammatory conditions and (3) by averting the increase in claudin-2 mRNA, a channel-forming TJ protein induced by pro-inflammatory cytokines. Taken together, these results strongly suggest that polyphenols presented and consumed in red wine as a mixture can reinforce and protect the intestinal barrier against inflammatory stimulus by affecting the TJ protein expression and, thus, without the need for purifying individual compounds, might represent a readily available therapeutic intervention against IBD and intestinal inflammation.

Luteolin efficiently fights intestinal inflammation. The inhibition of the JAK/STAT pathway by luteolin is a key mechanism.