Medications Activating Tubular Fatty Acid Oxidation Enhance the Protective Effects of Roux-en-Y Gastric Bypass Surgery in a Rat Model of Early Diabetic Kidney Disease.

William P Martin,Eoin P Brennan,Neil G Docherty,Anders Pedersen,Catherine Godson,Sanna Abrahamsson,Mahmoud Abdelaal,Yeong H D Chuah,Carel W Le Roux,Daniel Malmodin,Michaela Hutter,Lars Fändriks

doi:10.3389/fendo.2021.757228

Abstract

BackgroundRoux-en-Y gastric bypass surgery (RYGB) improves biochemical and histological parameters of diabetic kidney disease (DKD). Targeted adjunct medical therapy may enhance renoprotection following RYGB.MethodsThe effects of RYGB and RYGB plus fenofibrate, metformin, ramipril, and rosuvastatin (RYGB-FMRR) on metabolic control and histological and ultrastructural indices of glomerular and proximal tubular injury were compared in the Zucker Diabetic Sprague Dawley (ZDSD) rat model of DKD. Renal cortical transcriptomic (RNA-sequencing) and urinary metabolomic (1H-NMR spectroscopy) responses were profiled and integrated. Transcripts were assigned to kidney cell types through in silico deconvolution in kidney single-nucleus RNA-sequencing and microdissected tubular epithelial cell proteomics datasets. Medication-specific transcriptomic responses following RYGB-FMRR were explored using a network pharmacology approach. Omic correlates of improvements in structural and ultrastructural indices of renal injury were defined using a molecular morphometric approach.ResultsRYGB-FMRR was superior to RYGB alone with respect to metabolic control, albuminuria, and histological and ultrastructural indices of glomerular injury. RYGB-FMRR reversed DKD-associated changes in mitochondrial morphology in the proximal tubule to a greater extent than RYGB. Attenuation of transcriptomic pathway level activation of pro-fibrotic responses was greater after RYGB-FMRR than RYGB. Fenofibrate was found to be the principal medication effector of gene expression changes following RYGB-FMRR, which led to the transcriptional induction of PPARα-regulated genes that are predominantly expressed in the proximal tubule and which regulate peroxisomal and mitochondrial fatty acid oxidation (FAO). After omics integration, expression of these FAO transcripts positively correlated with urinary levels of PPARα-regulated nicotinamide metabolites and negatively correlated with urinary tricarboxylic acid (TCA) cycle intermediates. Changes in FAO transcripts and nicotinamide and TCA cycle metabolites following RYGB-FMRR correlated strongly with improvements in glomerular and proximal tubular injury.ConclusionsIntegrative multi-omic analyses point to PPARα-stimulated FAO in the proximal tubule as a dominant effector of treatment response to combined surgical and medical therapy in experimental DKD. Synergism between RYGB and pharmacological stimulation of FAO represents a promising combinatorial approach to the treatment of DKD in the setting of obesity.

Highlights

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD) [1, 2]
Improvements in glomerular injury of greater magnitude and lower variability were achieved by combining Roux-en-Y gastric bypass (RYGB) with type 2 diabetes medications to stimulate renal fatty acid oxidation (FAO), a mechanism of progressive DKD which was not addressed by RYGB alone [80, 81]
Fenofibrate was found to be the principal medication effector of gene expression changes following RYGB-FMRR; consequent induction of PPARaregulated FAO transcripts in the proximal tubule was a dominant response to RYGB-FMRR which strongly correlated with urinary abundance of nicotinamide metabolites and tricarboxylic acid (TCA) cycle intermediates

Summary

Introduction

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD) [1, 2]. Roux-en-Y gastric bypass (RYGB) is the surgical procedure for which the most data on renoprotection in type 2 diabetes exists [6,7,8]. Impaired renal tubular fatty acid oxidation (FAO) is implicated as a pathogenic driver of tubulointerstitial fibrosis in CKD [14]. Restoration of mitochondrial number and FAO by tubular epithelial-specific overexpression of the rate-limiting fatty acid shuttling enzyme, carnitine palmitoyltransferase 1A, attenuates experimental renal fibrosis [15]. We did not detect transcriptomic evidence of FAO induction following RYGB in the ZDF rat [12], suggesting that pharmacotherapy promoting FAO may complement the metabolic benefits of surgery vis-àvis renoprotection. Roux-en-Y gastric bypass surgery (RYGB) improves biochemical and histological parameters of diabetic kidney disease (DKD).

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Conclusion