Re: Urinary metabolic phenotyping the slc26a6 (Chloride-Oxalate Exchanger) null mouse model

摘要

The prevalence of renal stone disease is increasing, although it remains higher in men than in women when matched for age. While still somewhat controversial, several studies have reported an association between renal stone disease and hypertension, but this may be confounded by a shared link with obesity. However, independent of obesity, hyperoxaluria has been shown to be associated with hypertension in stone-formers and the most common type of renal stone is composed of calcium oxalate. The chloride-oxalate exchanger slc26a6 (also known as CFEX or PAT-1), located in the renal proximal tubule, was originally thought to have an important role in sodium homeostasis and thereby blood pressure control, but it has recently been shown to have a key function in oxalate balance by mediating oxalate secretion in the gut. We have applied two orthogonal analytical platforms (NMR spectroscopy and capillary-electrophoresis with UV detection) in parallel to characterize the urinary metabolic signatures related to the loss of the(. renal chloride-oxalate exchanger in slc26a6 null mice.Clear metabolic differentiation between the urinary profiles of the slc26a6 null and the wild type mice were observed using both methods, with the combination of NMR and CE-UV providing extensive coverage of the urinary metabolome. Key discriminating, metabolites included oxalate, m-hydroxy-phenylpropionylsulfate (m-HPPS), trimethylamine-N-oxide, glycolate and scyllo-inositol (higher in CFEX null mice) and hippurate, taurine, trimethylamine, and citrate (lower in slc26a6 null mice). In addition to the decreased efficiency of anion transport, several of these metabolites (hippurate, m-HPPS, methylamines) reflect alteration in gut microbial co-metabolic activities. Gender-related metabotypes were also observed in both wild type and slc26a6 null groups. Other urinary chemicals that showed a gender-specific pattern included trimethylamine, trimethylamine-N-oxide, citrate, sper-midine, guanidinoacetate, and 2-oxoisocaproate. The gender-dependent metabolic expression of the consequences of slc26a6 deletion might have relevance to the difference in prevalence of renal stone formation in men and women. The modification of the microbial metabolites is consistent with the fact that the slc26a6 transporter is found in a range of tissues, including the kidney and intestine, and provides further evidence for the 'long reach' of the microbiota in physiological and pathological processes.