We describe new agonists at succinate receptors that should facilitate further research on this understudied receptor.
BackgroundIschemia/reperfusion (I/R) is the most common cause of acute kidney injury (AKI). Its pathophysiology remains unclear. Metabolomics is dedicated to identify metabolites involved in (patho)physiological changes of integrated living systems. Here, we performed 1H-Nuclear Magnetic Resonance metabolomics using urine, serum and kidney samples from a mouse model of renal I/R.MethodsRenal 30-min ischemia was induced in 12-week-old C57BL/6J male mice by bilaterally clamping vascular pedicles, and was followed by 6, 24 or 48-hour reperfusion (n = 12/group). Sham-operated mice were used as controls. Statistical discriminant analyses, i.e. principal component analysis and orthogonal projections to latent structures (OPLS-DA), were performed on urine, serum and kidney lysates at each time-point. Multivariate receiver operating characteristic (ROC) curves were drawn, and sensitivity and specificity were calculated from ROC confusion matrix (with averaged class probabilities across 100 cross-validations).ResultsUrine OPLS-DA analysis showed a net separation between I/R and sham groups, with significant variations in levels of taurine, di- and tri-methylamine, creatine and lactate. Such changes were observed as early as 6 hours post reperfusion. Major metabolome modifications occurred at 24h post reperfusion. At this time-point, correlation coefficients between urine spectra and conventional AKI biomarkers, i.e. serum creatinine and urea levels, reached 0.94 and 0.95, respectively. The area under ROC curve at 6h, 24h and 48h post surgery were 0.73, 0.98 and 0.97, respectively. Similar discriminations were found in kidney samples, with changes in levels of lactate, fatty acids, choline and taurine. By contrast, serum OPLS-DA analysis could not discriminate sham-operated from I/R-exposed animals.ConclusionsOur study demonstrates that renal I/R in mouse causes early and sustained metabolomic changes in urine and kidney composition. The most implicated pathways at 6h and 24h post reperfusion include gluconeogenesis, taurine and hypotaurine metabolism, whereas protein biosynthesis, glycolysis, and galactose and arginine metabolism are key at 48h post reperfusion.
Mesenchymal stromal cells (MSC) have been demonstrated to attenuate renal ischemia/reperfusion (I/R) damage in rodent models. The mechanisms of such nephro-protection remain largely unknown. Furthermore, the optimal timing of MSC administration has been poorly investigated. Here, we compare the impact of MSC injection 7 days before (MSCD − 7) versus 1 day after (MSCD + 1) renal I/R in rats. Control groups received equivalent volumes of saline at similar time-points (SD − 7 and SD + 1). Right nephrectomy was performed, and left renal ischemia lasted 45 min. After 48-hour reperfusion, we observed significantly improved renal function parameters, reduced apoptotic index and neutrophil/macrophage infiltration in kidney parenchyma, and lower expression of tubular damage markers and pro-inflammatory cytokines in MSCD − 7 in comparison to MSCD + 1 and saline control groups. Next, comparative high-throughput RNA sequencing of MSCD − 7 vs. SD − 7 non-ischemic right kidneys highlighted significant down-regulation of fatty acid biosynthesis and up-regulation of PPAR-α pathway. Such a preferential regulation towards lipid catabolism was associated with decreased levels of lipid peroxidation products, i.e. malondialdehyde and 4-hydroxy-2-nonenal, in MSCD − 7 versus SD − 7 ischemic kidneys. Our findings suggest that MSC pretreatment may exert protective effects against renal I/R by modulating lipid metabolism in rats.
Aim: Dual Specificity Phosphatase 3 (DUSP3) regulates the innate immune response, with a putative role in angiogenesis. Modulating inflammation and perfusion contributes to renal conditioning against ischaemia/reperfusion (I/R). We postulate that the functional loss of DUSP3 is associated with kidney resistance to I/R. Methods: Ten C57BL/6 male WT and Dusp3 −/− mice underwent right nephrectomy and left renal I/R (30 min/48 hours). Renal injury was assessed based on serum levels of urea (BUN) and Jablonski score. The expression of CD31 and VEGF vascular markers was quantified by RT-qPCR and immuno-staining. Renal resistivity index (RRI) was measured in vivo by Doppler ultrasound. Comparative phosphoproteomics was conducted using IMAC enrichment of phosphopeptides. Inflammatory markers were quantified at both mRNA and protein levels in ischaemic vs non-ischaemic kidneys in WT vs Dusp3 −/− . Results: At baseline, we located DUSP3 in renal glomeruli and endothelial cells. CD31-positive vascular network was significantly larger in Dusp3 −/− kidneys compared to WT, with a lower RRI in Dusp3 −/− mice. Following I/R, BUN and Jablonski score were significantly lower in Dusp3 −/− vs WT mice. Phosphoproteomics highlighted a down-regulation of inflammatory pathways and up-regulation of phospho-sites involved in cell metabolism and VEGF-related See editorial article: Ivy J.R. 2022 Does renal ischaemia/reperfusion injury bite the DUSP3? Acta Physiol (Oxf). e13763.
Despite early renal carcinoma diagnosis is more frequent nowadays, ~25-30 % of patients have metastatic disease at presentation and another ~30 % develop recurrent or metastatic disease after radical treatment for localized disease. In recent years, treatment of renal carcinoma is increasing in complexity due to the inclusion of a number of effective systemic treatments prolonging survival and increasing the therapeutic strategies for tumor debulking, or even achieving surgical complete responses and prolonged disease-free intervals. Initial multimodal approaches with immunotherapeutic agents are now being validated in patients treated with the new-targeted agents. Patients are now able to receive an optimal therapeutic strategy seeking a longer survival with an acceptable life quality and avoiding unnecessary comorbidities. In this context and as an initial therapeutic approach, it is imperative to promote patients' selection with established prognostic models within a multidisciplinary team to assess the recommendation of a cytoreductive nephrectomy (CN), metastasectomy, and/or systemic treatment. In the context of mRCC, when feasible and in patients with favorable prognostic factors, the strategy should be to consider a CN or metastasectomy for tumor debulking in order to achieve free intervals of prolonged disease. By contrast, it is recommended to evaluate whether to perform a biopsy for histological diagnosis without nephrectomy in the following situations: high surgical risk, bulky metastatic disease or in specific sites (brain or liver) or ECOG PS 3/4. The following review covers from initial to recent studies on the integration of systemic treatment and surgery in the context of metastatic disease for an optimal multimodal management in renal carcinoma.
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