Oral cavity infection by the SARS-CoV-2: emphasizing the essence of masking and peptide therapeutics

The SARS-CoV-2 has infected many people globally with the ravaging COVID-19; a disease, which has become challenging for every aspect of modern healthcare. The saliva and oral mucosa are sites of high risk for increased viral loads, and aside from the usual epithelial functions like lining and protection, the oral mucosa is also specialized for crucial functions, such as secretion, mastication, sensory perception, and taste perception. The human ACE2 receptor has been extensively studied for its essential role in the regulation of blood pressure homeostasis. However, scRNA-Seq studies have revealed high expression levels of the protein in keratinized epithelial surfaces of the oral cavity. The SARS-CoV-2 have access to the host’s body by binding to the ACE2 receptor, leading to the cleavage and major conformational changes in the viral spike glycoprotein for the release of its nucleocapsid into the cellular cytoplasm. This proteolytic cleavage is carried out by the TMPRSS2 and cathepsin L. In this study, we harnessed the information from the binding interface of TMPRSS2 and PAI-1 (a protease inhibitor known to inhibit the TMPRSS2 and several other proteases) to design a potential therapeutic peptide for the inhibition of the TMPRSS2, while also emphasizing the need for preventive masking.

Posttranslational Modifications of the Mineralocorticoid Receptor and Cardiovascular Aging

During aging, the cardiovascular system is especially prone to a decline in function and to life-expectancy limiting diseases. Cardiovascular aging is associated with increased arterial stiffness and vasoconstriction as well as left ventricular hypertrophy and reduced diastolic function. Pathological changes include endothelial dysfunction, atherosclerosis, fibrosis, hypertrophy, inflammation, and changes in micromilieu with increased production of reactive oxygen and nitrogen species. The renin-angiotensin-aldosterone-system is an important mediator of electrolyte and blood pressure homeostasis and a key contributor to pathological remodeling processes of the cardiovascular system. Its effects are partially conveyed by the mineralocorticoid receptor (MR), a ligand-dependent transcription factor, whose activity increases during aging and cardiovascular diseases without correlating changes of its ligand aldosterone. There is growing evidence that the MR can be enzymatically and non-enzymatically modified and that these modifications contribute to ligand-independent modulation of MR activity. Modifications reported so far include phosphorylation, acetylation, ubiquitination, sumoylation and changes induced by nitrosative and oxidative stress. This review focuses on the different posttranslational modifications of the MR, their impact on MR function and degradation and the possible implications for cardiovascular aging and diseases.

Optimal Conditions for Expression of Enzymatic Activities in Bacillus Strains Essential for Production of Soumbara, a Functional Fermented Food Involved in Blood Pressure Homeostasis

Background: Soumbara is a traditional fermented food involved in the blood pressure homeostasis. The functional properties of this food strongly depend on the fermentative microbiota. In this study, we screened and identified at molecular level, some potential starters strain among the main microbiota associated with soumbara in Cote d’Ivoire, and investigated the conditions for optimal expression of their functional performance. Methods: We screened and identified by ribosomal gene sequencing, interesting microbial strains and conditions for optimal expression of their functional performance notably proteolytic, lipolytic, pectinolytic, amylolytic and cellulolytic activities was investigated using semi quantitative method. Results: The isolated microbiota was composed of 90.41 % of Bacillus strains, the rest being yeast and lactic acid bacteria. A total of 4 performant strains, specifically Bacillus subtilis (BS14P), Bacillus subtilis (KS16P), Bacillus velezensis (HS27M) and Bacillus pumilis (PS10P) were extracellular enzymes producing strains with halo diameter ranging between 1.9 and 2.8 cm. These strains grew optimally in the temperature range of 30- 35°C at pH 7-8. The largest enzyme producer Bacillus velezensis strain (HS27M) was remarkably able to grow well at relatively high temperature (40°C) and in a larger pH range (6-9). Proteolysis enzymes were produced optimally at 40-45°C, pH 7 whereas lipolysis occurred maximally at 40°C, pH 7. Likewise maximum pectinolytis, cellulolysis and amylolysis occurred at 45°C, pH range 7-8. Conclusion: This study suggests Bacillus velezensis HS27M as valuable starter cultures for the production of soumbara with bioactive and organoleptic quality.

“Dimerization of the Mineralocorticoid Receptor Ligand Binding Domain by helix 9, 10 and the F-domain”

In vertebrates, the mineralocorticoid receptor (MR) is a steroid-activated nuclear receptor (NR) that plays essential roles in water-electrolyte balance and blood pressure homeostasis. It belongs to the group of oxo-steroidian NRs, together with the glucocorticoid (GR), progesterone (PR), and androgen (AR) receptors. Classically, these oxo-steroidian NRs homodimerize and bind to specific genomic sequences to activate gene expression. NRs are multi-domain proteins, and dimerization is mediated by both the DNA (DBD) and ligand binding (LBD) domains, with the latter thought to provide the largest dimerization interface. However, at the structural level, the LBD dimerization of oxo-steroidian receptors has remained largely a matter of debate. This is linked to the receptor refractory expression, purification and crystallization. As a result, there is currently no consensus on a common homodimer assembly across the 4 receptors, i.e. GR, PR, AR and MR, despite their sequence homology. Examining the available MR LBD crystals and using widely plebiscited tools such as PISA, PRISM and EPPIC, and the MM/PBSA method, we have determined that an interface mediated by the helices H9 and H10 of the LBD as well as by the F domain presents the features of a biological protein-protein interaction surface. This interface which has been observed in both GRα and MR crystals, distinguished itself among other contacts and provided for the first time a homodimer architecture that is common to both oxo-steroidian receptors.

The influence of barosensory vessel mechanics on the vascular sympathetic baroreflex: insights into aging and blood pressure homeostasis

We assessed the influence of barosensory vessel mechanics (magnitude and rate of unloading and time spent unloaded) as a surrogate for baroreceptor unloading. In young men, aortic unloading mechanics are important in regulating the operating point of the vascular sympathetic baroreflex, whereas in middle-aged men, these arterial mechanics do not influence this operating point. The age-related increase in resting muscle sympathetic nerve activity does not appear to be driven by altered baroreceptor input from stiffer barosensory vessels.

Endothelial Sphingolipid De Novo Synthesis Controls Blood Pressure by Regulating Signal Transduction and NO via Ceramide

Ceramides are sphingolipids that modulate a variety of cellular processes via 2 major mechanisms: functioning as second messengers and regulating membrane biophysical properties, particularly lipid rafts, important signaling platforms. Altered sphingolipid levels have been implicated in many cardiovascular diseases, including hypertension, atherosclerosis, and diabetes mellitus–related conditions; however, molecular mechanisms by which ceramides impact endothelial functions remain poorly understood. In this regard, we generated mice defective of endothelial sphingolipid de novo biosynthesis by deleting the Sptlc2 (long chain subunit 2 of serine palmitoyltransferase)—the first enzyme of the pathway. Our study demonstrated that endothelial sphingolipid de novo production is necessary to regulate (1) signal transduction in response to NO agonists and, mainly via ceramides, (2) resting eNOS (endothelial NO synthase) phosphorylation, and (3) blood pressure homeostasis. Specifically, our findings suggest a prevailing role of C16:0-Cer in preserving vasodilation induced by tyrosine kinase and GPCRs (G-protein coupled receptors), except for Gq-coupled receptors, while C24:0- and C24:1-Cer control flow-induced vasodilation. Replenishing C16:0-Cer in vitro and in vivo reinstates endothelial cell signaling and vascular tone regulation. This study reveals an important role of locally produced ceramides, particularly C16:0-, C24:0-, and C24:1-Cer in vascular and blood pressure homeostasis, and establishes the endothelium as a key source of plasma ceramides. Clinically, specific plasma ceramides ratios are independent predictors of major cardiovascular events. Our data also suggest that plasma ceramides might be indicative of the diseased state of the endothelium.

Angiotensin II-mediated nondipping during sleep in healthy humans: effects on baroreflex function at subsequent daytime

Blood pressure dipping at night is mediated by sleep-inherent, active downregulation of sympathetic vascular tone. Concomitantly, activity of the renin-angiotensin system is reduced, which might contribute to the beneficial effect of baroreflex downward resetting on daytime blood pressure homeostasis. To evaluate whether experimental nondipping mediated by angiotensin II during sleep would alter blood pressure and baroreflex function the next day in healthy humans, angiotensin-II or placebo (saline) was infused for a 7-h period at night, preventing blood pressure dipping in 11 sleeping normotensive individuals (5 males, balanced, crossover design). Baroreflex function was assessed about 1 h upon awakening and stop of infusion via microneurographic recordings of muscle sympathetic nerve activity (MSNA), showing that resting MSNA was significantly increased following angiotensin II nondipping compared with placebo ( P = 0.029), whereas blood pressure and heart rate remained unchanged. Baroreflex sensitivity in response to vasoactive drug challenge was preserved, and neuroendocrine markers of fluid balance and electrolytes did not differ between conditions. Ambulatory blood pressure during subsequent daytime was not altered. Data were compared with analog experiments previously performed within the same subjects during awake daytime (ANCOVA). We conclude that angiotensin-II mediated nocturnal nondipping did not induce blood pressure elevation at subsequent daytime in healthy humans but was linked to increased vasoconstrictive sympathetic activity. This is in contrast to a prolonged increase in blood pressure in corresponding daytime experiments of the same individuals. Evidently, sleep strongly preserves normotensive blood pressure homeostasis in healthy humans.