Sodium/glucose cotransporter 2 (SGLT2) inhibitors are oral hypoglycemic agents used to treat patients with diabetes mellitus. SGLT2 inhibitors block reabsorption of filtered glucose by inhibiting SGLT2, the primary glucose transporter in the proximal tubular cell (PTC), leading to glycosuria and lowering of serum glucose. We examined the renoprotective effects of the SGLT2 inhibitor empagliflozin to determine whether blocking glucose entry into the kidney PTCs reduced the inflammatory and fibrotic responses of the cell to high glucose. We used an in vitro model of human PTCs. HK2 cells (human kidney PTC line) were exposed to control 5 mM, high glucose (HG) 30 mM or the profibrotic cytokine transforming growth factor beta (TGFβ1; 0.5 ng/ml) in the presence and absence of empagliflozin for up to 72 h. SGLT1 and 2 expression and various inflammatory/fibrotic markers were assessed. A chromatin immunoprecipitation assay was used to determine the binding of phosphorylated smad3 to the promoter region of the SGLT2 gene. Our data showed that TGFβ1 but not HG increased SGLT2 expression and this occurred via phosphorylated smad3. HG induced expression of Toll-like receptor-4, increased nuclear deoxyribonucleic acid binding for nuclear factor kappa B (NF-κB) and activator protein 1, induced collagen IV expression as well as interleukin-6 secretion all of which were attenuated with empagliflozin. Empagliflozin did not reduce high mobility group box protein 1 induced NF-κB suggesting that its effect is specifically related to a reduction in glycotoxicity. SGLT1 and GLUT2 expression was not significantly altered with HG or empagliflozin. In conclusion, empagliflozin reduces HG induced inflammatory and fibrotic markers by blocking glucose transport and did not induce a compensatory increase in SGLT1/GLUT2 expression. Although HG itself does not regulate SGLT2 expression in our model, TGFβ increases SGLT2 expression through phosphorylated smad3.
The use of enlarged breath shields has been suggested as part of a wide range of infection control measures implemented during the COVID-19 pandemic. Breath shields have long been a standard feature of slit lamps and act as a physical barrier between the examiner and subject but there is an absence of evidence on their effectiveness in reducing droplet transmission and respiratory infections.SARS-CoV-2 shares many of the features of other respiratory viruses including SARS-CoV-1 and is thought to be commonly spread though respiratory droplets (>5 μm) and fomites [1]. Fomites are formed either from droplets settling on surfaces or through direct contamination from touching mucosal surfaces. Smaller aerosolised droplet nuclei (≤5 μm) can travel further and remain in air longer. They have been shown to carry viable virus particles in experimental conditions [2] but are not thought to be a common mode of transmission of COVID-19 [1]. The risk of transmission from tears is also thought to be low [3].We sought to examine the efficacy of facemasks and standard and augmented slit lamp breath shields using a breathing simulator. These have been described previously and generally comprise of a particle source, commonly a nebuliser attached to a bellows or air tank and a particle detector which can consist of a laser particle counter [4] or an impinger from which viral particles can be sampled from air, cultured in cells and detected as plaques [5]. Direct visual inspection of sprayed dye droplets has also been described as a way to test eye protection [6,7]. We experimented using nebulised fluorescein 2% but were unable to capture sufficient dye to determine the patterns of droplet distribution.We used a mouthpiece nebuliser (Galemed Corp, Taiwan) containing 5 ml of 0.9% saline as our particle source and attached it to a 500 ml paediatric bag valve mask that was manually compressed 12 times per minute to simulate normal adult tidal breathing. The device produces a range of particles from 1 to 25 μm with median mass aerodynamic diameter of 3.8 μm. We used a Met One A2400 optical particle counter (Hach Co, Loveland, CO) operating at a flow rate of one cubic foot per minute to detect particles that reached the eyepiece over a 1-min period. This was initially performed without any shielding, and then repeated with the standard (11 × 11 × 0.2 cm) and augmented (45 × 44 × 0.2 cm) acrylic shields attached to the slit lamp objective lens (Fig. 1). We then tested the effect of placing a fluid resistant surgical facemask (BARRIER 4313, Mölnlycke Healthcare, Sweden) over the nebuliser mouthpiece alone and in combination with the large shield. The slit lamp arm was offset to 60°throughout and each barrier was tested five times. Linear regression was used to determine the effect of shield type and particle size on particle count. All analyses were performed using Stata v14.With no shield in place, the mean log particle count was 3.59 (95% CI: 3.48-3.70). There was a significant reduction to 3.01 (95% CI: 2.90-3.13, p < 0.01) with the s...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.