Metabolomics analysis for hydroxy-L-proline-induced calcium oxalate nephrolithiasis in rats based on ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry.

Songyan Gao,Xingang Cui,Xin Dong,Rui Yang,Na Li,Jiarong Ding,Wei Chen,Zhongjiang Peng,Hongtao Lu

doi:10.1038/srep30142

Abstract

About 80% of kidney stones are composed of calcium oxalate (CaOx) with variable amounts of calcium phosphate, and hyperoxaluria is considered as an important factor of CaOx nephrolithiasis. However, the underlying metabolic mechanisms of CaOx nephrolithiasis remain undefined. In this study, we successfully developed a rat model with hydroxy-L-proline (HLP) -induced CaOx nephrolithiasis. Rats were continuously orally administrated with HLP for 28 days. Urine and blood samples were collected from the rats treated with or without HLP at four different time points. UPLC–Q-TOF/MS was applied to profile the abundances of metabolites. To obtain more comprehensive analysis of metabolic profiling spectrum, combination of RP-LC and HILIC were applied. We identify 42 significant differential metabolites in the urine, and 13 significant differential metabolites in the blood. Pathway analysis revealed that the pathways involved in amino acid metabolism, taurine metabolism, bile acid synthesis, energy metabolism, TCA cycle, purine metabolism, vitamin metabolism, nicotinic acid and nicotinamide metabolism have been modulated by HLP treatment. This study suggested that a number of metabolic pathways are dysfunctional in the HLP induced crystal kidney injury, and further studies on those pathways are warranted to better understand the metabolic mechanism of CaOx nephrolithiasis.

Highlights

Nephrolithiasis is a common urinary tract disease which is often accompanied by symptoms of renal colic and hematuria in clinic
The urinary phosphorus creatinine ratio had significantly changed across different time points in H group (P < 0.05) (Fig. 1D), while urinary magnesium creatinine ratios significantly increased in HLP-treated rats, compared to those in the control rats (P < 0.05) (Fig. 1E)
Betaine synthesized in the kidney, but mainly in the cortex and outer medulla, accumulated betaine synthesis and osmotic regulation were occurred in different parts of the kidney, and studies show that Betaine metabolism in kidney cells are extracellular permeability of the adjust

Summary

Introduction

Nephrolithiasis is a common urinary tract disease which is often accompanied by symptoms of renal colic and hematuria in clinic. An elevated level of urinary oxalate is considered as an important factor of CaOx nephrolithiasis. Oxalate metabolism in human and rats are considered basically the same[8], and rat model building stones can be used to study mechanisms of human kidney stone formation. Khan et al.[15] have successfully developed an HLP-induced rat model of kidney stones, which is closer to human kidney stone formation process. We constructed a HLP-induced CaOx nephrolithiasis model with Sprague-Dawley (SD) rat and performed metabolomics analyses for the urine and serum samples at different time points after HLP treatment using UPLC-Q-TOF/MS. This study provided important data for the metabolic mechanism of HLP-induced crystal renal injury

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Discussion

Conclusion