Biology subjects

Bhalla, V.

Publications and source records attributed to Bhalla, V..

6 recordsLinked to original sources

bioRxiv2023

Kidney single-cell transcriptomes uncover SGLT2i-induced metabolic reprogramming via restoring glycolysis and fatty acid oxidation

Approximately 40% of individuals with chronic kidney disease have type 2 diabetes mellitus, and diabetic kidney disease is the leading cause of end-stage kidney disease worldwide. Inhibitors of sodium-glucose cotransporter 2 (SGLT2) have been demonstrated to be effective in glucose control, improving cardiovascular outcomes and the progression of kidney disease. However, the protective role of SGLT2 inhibition on kidney metabolism is not fully understood. To explore these mechanisms further, we conducted analysis of publicly available single-cell RNA sequencing data of db/db mice treated with an SGLT2 inhibitor(dapagliflozin) and accompanying controls. We found that proximal tubule cells exhibited impaired glycolysis and high fatty acid oxidation in diabetes compared with control mice. SGLT2 inhibition reversed this metabolic dysfunction by reducing glycolysis and its substrate accumulation. SGLT2 inhibition also upregulates high fatty oxidation without increasing the uptake of fatty acids and elongation, along with low lipotoxicity. Surprisingly, both SGLT2(+) and SGLT2(-) cells show gene consistent changes in expression of metabolic genes, consistent with a non-cell autonomous effect of dapagliflozin treatment. This study demonstrates the protective role of SGLT2 inhibition via restoring metabolic dysfunction.

genetics↗

bioRxiv2023

Esm-1 mediates transcriptional polarization associated with diabetic kidney disease

BackgroundEsm-1, endothelial cell-specific molecule-1, is a susceptibility gene for diabetic kidney disease (DKD) and is a cytokine- and glucose-regulated, secreted proteoglycan, that is notably expressed in kidney and attenuates inflammation and albuminuria. Esm1 has restricted expression at the vascular tip during development but little is known about its expression pattern in mature tissues, and its precise effects in diabetes. MethodsWe utilized publicly available single-cell RNA sequencing data to explore the characteristics of Esm1 expression in 27,786 renal endothelial cells obtained from four adult human and three mouse databases. We validated our findings using bulk transcriptome data from an additional 20 healthy subjects and 41 patients with DKD and using RNAscope. Using correlation matrices, we relate Esm1 expression to the glomerular transcriptome and evaluated these matrices with systemic over-expression of Esm-1. ResultsIn both mice and humans, Esm1 is expressed in a subset of all renal endothelial cell types and represents a minority of glomerular endothelial cells. In patients, Esm1(+) cells exhibit a highly conserved enrichment for blood vessel development genes. With diabetes, these cells are fewer in number and profoundly shift expression to reflect chemotaxis pathways. Analysis of these gene sets highlight candidate genes such as Igfbp5 for cross talk between cell types. We also find that diabetes induces correlations in the expression of large clusters of genes, within cell type-enriched transcripts. Esm1 significantly correlates with a majority genes within these clusters, delineating a glomerular transcriptional polarization reflected by the magnitude of Esm1 deficiency. In diabetic mice, these gene clusters link Esm1 expression to albuminuria, and over-expression of Esm-1 reverses the expression pattern in many of these genes. ConclusionsA comprehensive analysis of single cell and bulk transcriptomes demonstrates that diabetes correlates with lower Esm1 expression and with changes in the functional characterization of Esm1(+) cells. Esm1 is both a marker for glomerular transcriptional polarization, and a mediator that re-orients the transcriptional program in DKD.

cell biology↗

bioRxiv2021

Endothelial Cell-Specific Molecule-1 Inhibits Albuminuria in Diabetic Mice

Diabetic kidney disease (DKD) is the most common cause of kidney failure in the world, and novel predictive biomarkers and molecular mechanisms of disease are needed. Endothelial cell-specific molecule-1 (Esm-1) is a secreted proteoglycan that attenuates inflammation. We previously identified that a glomerular deficiency of Esm-1 associates with more pronounced albuminuria and glomerular inflammation in DKD-susceptible relative to DKD-resistant mice, but its contribution to DKD remains unexplored. In this study, we show that lower circulating Esm-1 predicts progressive stages of albuminuria in patients with diabetes. In DKD-susceptible mice, Esm-1 inversely correlates with albuminuria and glomerular leukocyte infiltration. Using hydrodynamic tail-vein injection, we show that over-expression of either mouse or human Esm-1 reduces diabetes-induced albuminuria relative to saline-injected controls independent of leukocyte infiltration. Using a complementary approach, we find that constitutive deletion of Esm-1 in DKD-resistant mice increases the degree of diabetes-induced albuminuria versus wild-type controls. Mechanistically, over-expression of Esm-1 attenuates diabetes-induced podocyte injury. By glomerular RNAseq, we identify that Esm-1 attenuates diabetes-induced up-regulation of interferon-stimulated genes, and Esm-1 inhibits expression of kidney disease-promoting and interferon-related genes, including Ackr2 and Cxcl11. In conclusion, we demonstrate that Esm-1 protects against diabetes-induced albuminuria, and podocytopathy, possibly through select interferon signaling.

immunology↗

bioRxiv2021

Proximal and Distal Nephron-specific Adaptation to Furosemide

Furosemide, a widely prescribed diuretic for edema-forming states, inhibits sodium reabsorption in the thick ascending limb of the nephron. Tubular adaptation to diuretics has been observed, but the range of mechanisms along the nephron has not been fully explored. Using morphometry, we show that furosemide induces renal tubular epithelial hyperplasia selectively in distal nephron segments. By comparison, we find progressive cellular hypertrophy in proximal and distal nephron segments. We next utilize single cell RNA sequencing of vehicle- and furosemide-treated mice to define potential mechanisms of diuretic resistance. Consistent with distal tubular cell hyperplasia, we detect a net increase in DCT cell number and Birc5, an anti-apoptotic and pro-growth gene, in a subset of DCT cells, as the most prominently up-regulated gene across the nephron. We also map a gradient of cell-specific transcriptional changes congruent with enhanced distal sodium transport. Furosemide stimulates expression of the mitogen IGF-1. Thus, we developed a mouse model of inducible deletion of renal tubular IGF-1 receptor and show reduced kidney growth and proximal, but not distal, tubular hypertrophy by furosemide. Moreover, genes that promote enhanced bioavailability of IGF-1 including Igfbp1 and Igfbp5 are significantly and differentially expressed in proximal tubular segments and correspond to IGF-1R-dependent hypertrophy. In contrast, downstream PI3-kinase signaling genes including Pdk1, Akt1, Foxo3, FKBP4, Eif2BP4, and Spp1 are significantly and differentially expressed in distal nephron segments and correspond to IGF-1R-independent hypertrophy. These findings highlight novel mechanisms of tubular remodeling and diuretic resistance, provide a repository of transcriptional responses to a common drug, and expand the implications of long-term loop diuretic use for human disease.

physiology↗

bioRxiv2018

Urinary biomarkers and cardiovascular outcomes in the UK Biobank: observational and Mendelian randomization analyses

BackgroundUrinary biomarkers are associated with hypertension and cardiovascular disease (CVD), but the nature of these associations is incompletely understood.\n\nMethodsWe performed multivariable-adjusted regression models to assess associations of urinary sodium-potassium ratio (UNa/UK), and urinary albumin adjusted for creatinine (UAlb/UCr) with cardiovascular risk factors, CVD and type 2 diabetes (T2D) in 478,311 participants of the UK Biobank. Further, we studied above associations separately in men and women, and assessed the causal relationships of these kidney biomarkers with cardiovascular outcomes using the two-sample Mendelian randomization (MR) approach.\n\nResultsIn observational analyses, UNa/UK showed significant inverse associations with atrial fibrillation (AF), coronary artery disease (CAD), ischemic stroke, lipid-lowering medication and T2D. In contrast, UAlb/UCr showed significant positive associations with AF, CAD, heart failure, hemorrhagic stroke, lipid-lowering medication and T2D. We found a positive association between UNa/UK and albumin with blood pressure (BP), as well as with adiposity-related measures. Generally, we detected consistent directionality in sex-stratified analyses, with some evidence for sex differences in the associations of urinary biomarkers with T2D and obesity. After correcting for potential horizontal pleiotropy, we found evidence of causal associations of UNa/UK and albumin with systolic BP (betaSBP[≥]2.63; betaDBP[≥]0.85 SD increase in systolic BP per SD change UNa/UK and UAlb/UCr; P[≤]0.038), and of albumin with T2D (odds ratio=1.33 per SD change in albumin, P=0.023).\n\nConclusionOur Mendelian randomization analyses mirror and extend findings from randomized interventional trials which have established sodium intake as a risk factor for hypertension. In addition, we detect a feed-back causal loop between albumin and hypertension, and our finding of a bidirectional causal association between albumin and T2D reflects the well-known nephropathy in T2D.

epidemiology↗

bioRxiv2017

Murine Glomerular Transcriptome Links Endothelial Cell-Specific Molecule-1 Deficiency With Susceptibility To Diabetic Nephropathy

Diabetic nephropathy (DN) is the leading cause of kidney disease; however, there are no early biomarkers and no cure. Thus, there is a large unmet need to predict which individuals will develop nephropathy and to understand the molecular mechanisms which govern this susceptibility. We compared the glomerular transcriptome from mice with distinct susceptibilities to DN, and identified differential regulation of genes that modulate inflammation. From these genes, we identified endothelial cell specific molecule-1 (Esm-1), as a glomerular-enriched determinant of resistance to DN. Glomerular Esm-1 mRNA and protein were lower in DN-susceptible, DBA/2, compared to DN-resistant, C57BL/6, mice. We demonstrated higher Esm-1 secretion from primary glomerular cultures of diabetic mice, and high glucose was sufficient to increase Esm-1 mRNA and protein secretion in both strains of mice. However, induction was significantly attenuated in DN-susceptible mice. Urine Esm-1 was also significantly higher only in DN-resistant mice. Moreover, using intravital microscopy and a biomimetic microfluidic assay, we showed that Esm-1 inhibited rolling and transmigration in a dose-dependent manner. For the first time we have uncovered glomerular-derived Esm-1 as a potential non-invasive biomarker of DN. Esm-1 inversely correlates with disease susceptibility and inhibits leukocyte infiltration, a critical factor in protecting the kidney from DN.

immunology↗