Inhibitors of the proximal tubular sodium glucose cotransporter SGLT2 are natriuretic and they lower blood pressure. There are reports that the activities of SGLT2 and the Na+-H+-exchanger, NHE3, are coordinated. If so, then part of the natriuretic response to an SGLT2 inhibitor is mediated by suppressing NHE3. To examine this further, we compared the effects of the SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in non-diabetic mice with tubule-specific NHE3 knock-down (NHE3-ko) and wild-type littermates (WT). A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na+ and bicarbonate, and raised urine pH in WT, but not in NHE3-ko. Chronic empagliflozin treatment tended to lower SBP despite higher renal renin mRNA expression, and lowered the ratio of SBP to renin mRNA, indicating volume loss. This effect of empagliflozin depended on tubular NHE3. In diabetic Akita mice, chronic empagliflozin enhanced phosphorylation of NHE3 (S552/S605), changes previously linked to lesser NHE3-mediated reabsorption. Chronic empagliflozin also increased expression of genes involved with renal gluconeogenesis, bicarbonate regeneration, and ammonium formation. While this could reflect compensatory responses to acidification of proximal tubular cells resulting from reduced NHE3 activity, these effects were at least in part independent of tubular NHE3 and potentially indicated metabolic adaptations to urinary glucose loss. Moreover, empagliflozin increased luminal α-ketoglutarate, which may serve to stimulate compensatory distal NaCl reabsorption, while co-generated and excreted ammonium balances urine losses of this "potential bicarbonate". The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin.

Inhibitors of the Na+-glucose cotransporter SGLT2 enhance urinary glucose and urate excretion and lower plasma urate levels. The mechanisms remain unclear, but a role for enhanced glucose in the tubular fluid, which may interact with tubular urate transporters, such as the glucose transporter GLUT9 or the urate transporter URAT1, has been proposed. Studies were performed in nondiabetic mice treated with the SGLT2 inhibitor canagliflozin and in gene-targeted mice lacking the urate transporter Glut9 in the tubule or in mice with whole body knockout of Sglt2, Sglt1, or Urat1. Renal urate handling was assessed by analysis of urate in spontaneous plasma and urine samples and normalization to creatinine concentrations or by renal clearance studies with assessment of glomerular filtration rate by FITC-sinistrin. The experiments confirmed the contribution of URAT1 and GLUT9 to renal urate reabsorption, showing a greater contribution of the latter and additive effects. Genetic and pharmacological inhibition of SGLT2 enhanced fractional renal urate excretion (FE-urate), indicating that a direct effect of the SGLT2 inhibitor on urate transporters is not absolutely necessary. Consistent with a proposed role of increased luminal glucose delivery, the absence of Sglt1, which by itself had no effect on FE-urate, enhanced the glycosuric and uricosuric effects of the SGLT2 inhibitor. The SGLT2 inhibitor enhanced renal mRNA expression of Glut9 in wild-type mice, but tubular GLUT9 seemed dispensable for the increase in FE-urate in response to canagliflozin. First evidence is presented that URAT1 is required for the acute uricosuric effect of the SGLT2 inhibitor in mice.

Studies associated with MS induced oxidative stress- and inflammation- mediated signalling pathways along with critical miRs help in better understanding of the pathophysiology of atherosclerosis. Several key molecules discussed in this review could be potent target for the prevention and treatment of atherosclerosis.

The non-structural protein (nsp)-3 of SARS-CoV2 coronavirus is sought to be an essential target protein which is also named as papain-like protease (PLpro). This protease cleaves the viral polyprotein, but importantly in human host it also removes ubiquitin-like interferon-stimulated gene 15 protein (ISG15) from interferon responsive factor 3 (IRF3) protein which ultimately downregulates the production of type I interferon leading to weakening of immune response. GRL0617 is the most potent known inhibitor for PLpro that was initially developed for SARS outbreak of 2003. The PLpro of SARS-CoV and CoV2 share 83% sequence identity but interestingly have several identical conserved amino acids that suggests GRL0617 to be an effective inhibitor for PLpro of SARS-CoV2. GRL0617 is a naphthalene-based molecule and interacts with Tyr268 of SARS-CoV2-PLpro (and Tyr269 of SARS-CoV-PLpro). To identify PLpro inhibitors, we prepared a library of secondary metabolites from fungi with aromatic nature and docked them with PLpro of SARS-CoV and SARS-CoV2. We found six hits which interacts with Tyr268 of SARS-CoV2-PLpro (and Tyr269 of SARS-CoV-PLpro). More surprisingly the top hit, Fonsecin, has naphthalene moiety in its structure, which recruits Tyr268 of SARS-CoV2-PLpro (and Tyr269 of SARS-CoV-PLpro) and has binding energy at par with control (GRL0617). Molecular dynamics (MD) simulation showed Fonsecin to interact with Tyr268 of SARS-CoV2-PLpro more efficiently than control (GRL0617) and interacting with a greater number of amino acids in the binding cleft of PLpro. Graphic abstract

Bone regeneration is a multi-step, overlapping process, in which angiogenesis and osteogenesis are the key players. Several attempts have been made to promote angiogenesis-coupled osteogenesis using scaffolding technology. However, the recreation of functional vasculature during bone regeneration is an unparalleled challenge. In this study, a dual drug-delivering polycaprolactone-collagen fibrous scaffold is reported to promote early osteogenesis and angiogenesis. Simvastatin as a pro-angiogenic and dexamethasone as an osteoinductive drug were encapsulated to functionalize the electrospun fibers. The optically transparent fibrous mat represented the sustained and sequential release of drugs for 28 days. The fibrous mesh increased cell proliferation and enhanced the osteogenic differentiation up to 21 days. The alkaline phosphatase activity and mineral deposition were comparatively higher on dual drug-releasing fibers when compared to control fibers. The dual drug-releasing osteoconductive fibers demonstrated osteogenesis as early as 7 days with a 3.7 and 1.5 fold increase in the expression of osteogenic differentiation markers (RUNX2 and osteocalcin), respectively. In vitro angiogenesis using primary human umbilical vein endothelial cells (pHUVECs) showed no significant difference in cell proliferation among control fibers and dual drug-releasing fibers. However, the angioinductive nature of simvastatin released from the fibers demonstrated tube formation and 2 fold higher angiogenic score. The mRNA and protein expression study of angiogenic markers (VEGFR2 and eNOS) by polymerase chain reaction and western blotting depicted the angioinducing potential of dual drug-releasing fibers. VEGFR2 and eNOS mRNA expressions increased by 1.1 and 1.6 fold, respectively, whereas their protein expression increased by 3.2 and 1.7 fold, respectively. The overall results demonstrate the synergistic effect of osteoconductive substrate and osteoinductive dual drugs to promote early osteogenesis, and release of the pro-angiogenic drug promotes angiogenesis.

Na+-glucose cotransporter (SGLT)1 mediates glucose reabsorption in late proximal tubules. SGLT1 also mediates macula densa (MD) sensing of an increase in luminal glucose, which increases nitric oxide (NO) synthase 1 (MD-NOS1)-mediated NO formation and potentially glomerular filtratrion rate (GFR). Here, the contribution of SGLT1 was tested by gene knockout (−/−) in type 1 diabetic Akita mice. A low-glucose diet was used to prevent intestinal malabsorption in Sglt1−/− mice and minimize the contribution of intestinal SGLT1. Hyperglycemia was modestly reduced in Sglt1−/− versus littermate wild-type Akita mice (480 vs. 550 mg/dl), associated with reduced diabetes-induced increases in GFR, kidney weight, glomerular size, and albuminuria. Blunted hyperfiltration was confirmed in streptozotocin-induced diabetic Sglt1−/− mice, associated with similar hyperglycemia versus wild-type mice (350 vs. 385 mg/dl). Absence of SGLT1 attenuated upregulation of MD-NOS1 protein expression in diabetic Akita mice and in response to SGLT2 inhibition in nondiabetic mice. During SGLT2 inhibition in Akita mice, Sglt1−/− mice had likewise reduced blood glucose (200 vs. 300 mg/dl), associated with lesser MD-NOS1 expression, GFR, kidney weight, glomerular size, and albuminuria. Absence of Sglt1 in Akita mice increased systolic blood pressure, associated with suppressed renal renin mRNA expression. This may reflect fluid retention due to blunted hyperfiltration. SGLT2 inhibition prevented the blood pressure increase in Sglt1−/− Akita mice, possibly due to additive glucosuric/diuretic effects. The data indicate that SGLT1 contributes to diabetic hyperfiltration and limits diabetic hypertension. Potential mechanisms include its role in glucose-driven upregulation of MD-NOS1 expression. This pathway may increase GFR to maintain volume balance when enhanced MD glucose delivery indicates upstream saturation of SGLTs and thus hyperreabsorption.

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These results suggest that exercise-induced up-regulation of tumor necrosis factor-alpha before stroke and extracellular signal-regulated kinase 1/2 phosphorylation play a role in decreasing brain inflammation by regulating matrix metalloproteinase-9 activity.