Impaired Citric Acid Cycle in Nondiabetic Chronic Kidney Disease

Chronic kidney disease (CKD) influencesmore than 10% of adult population worldwide (Hill et al., 2016). Among this population, many of them could progress into the end stage renal disease and finally require the therapies of kidney transplantation or dialysis. Thus, it is of vital importance in retarding the progression of CKDs during the early stage (stages 1–2) via an effective intervention. Unfortunately, by now, the nephrologists still lack satisfactory tools in dealing with this issue because of the elusive understanding on the common mechanisms mediating the CKD progression. Recently, metabolomics study revealed a new aspect of CKD. In diabetic kidney disease, Sharma et al. reported a marked alteration of 12metabolites inmitochondrialmetabolic pathways, which was not seen in the diabetic patients without CKD, suggesting that such an abnormality ismore relevantwith the kidney injury but not hyperglycemia (Sharma et al., 2013).Moreover, this study further raised the question thatwhether such a phenomenon also exists in the nondiabetic CKD population. Importantly, Hallan et al. performed a study in nondiabetic CKD patients and found an abnormality of citric acid cycle using the urine and blood samples along with the partial confirmation in renal biopsy specimens (Hallan et al., 2017). The similar findings from two reports highly suggested a common phenomenon of the impairment of mitochondrial metabolism in CKDs. In agreement with above findings, recent studies from CKD animals also confirmed the existence of mitochondrial dysfunction in kidneys undergoing the chronic injury, and targeting the mitochondria could ameliorate CKD (Sun et al., 2014; Zhao et al., 2017).