Cardiorenal syndrome type 3 (CRS-3) is damage to the heart following acute kidney injury (AKI). Although many experiments have found that inflammation, oxidative stress, and cardiomyocyte death are involved in cardiomyocyte pathophysiological alterations during CRS-3, they lack a non-bias analysis to figure out the primary mediator of cardiac dysfunction. Herein proteomic analysis was operated in CRS-3 and growth factor receptor-bound protein 2 (Grb2) was identified as a regulator involving AKI-related myocardial damage. Increased Grb2 was associated with cardiac diastolic dysfunction and mitochondrial bioenergetics impairment; these pathological changes could be reversed through the administration of a Grb2-specific inhibitor during AKI. Molecular investigation illustrated that augmented Grb2 promoted cardiomyocyte mitochondrial metabolism disorder through inhibiting the Akt/mTOR signaling pathway. Besides that, Mouse Inflammation Array Q1 further identified IL-6 as the upstream stimulator of Grb2 upregulation after AKI. Exogenous administration of IL-6 induced cardiomyocyte damage and mitochondrial bioenergetics impairment, whereas these effects were nullified in cardiomyocytes pretreated with Grb2 inhibitor. Our results altogether identify CRS-3 to be caused by the upregulations of IL-6/Grb2 which contribute to cardiac dysfunction through inhibiting the Akt/mTOR signaling pathway and inducing cardiomyocyte mitochondrial bioenergetics impairment. This finding provides a potential target for the clinical treatment of patients with CRS-3.

BackgroundUnderstanding the acute kidney injury (AKI) microenvironment changes and the complex cellular interaction is essential to elucidate the mechanisms and develop new targeted therapies for AKI.MethodsWe employed unbiased single-cell RNA sequencing to systematically resolve the cellular atlas of kidney tissue samples from mice at 1, 2 and 3 days after ischemia-reperfusion AKI and healthy control. The single-cell transcriptome findings were validated using multiplex immunostaining, western blotting, and functional experiments.ResultsWe constructed a systematic single-cell transcriptome atlas covering different AKI timepoints with immune cell infiltration increasing with AKI progression. Three new proximal tubule cells (PTCs) subtypes (PTC-S1-new/PTC-S2-new/PTC-S3-new) were identified, with upregulation of injury and repair-regulated signatures such as Sox9, Vcam1, Egr1, and Klf6 while with downregulation of metabolism. PTC-S1-new exhibited pro-inflammatory and pro-fibrotic signature compared to normal PTC, and trajectory analysis revealed that proliferating PTCs were the precursor cell of PTC-S1-new, and part of PTC-S1-new cells may turn into PTC-injured and then become fibrotic. Cellular interaction analysis revealed that PTC-S1-new and PTC-injured interacted closely with infiltrating immune cells through CXCL and TNF signaling pathways. Immunostaining validated that injured PTCs expressed a high level of TNFRSF1A and Kim-1, and functional experiments revealed that the exogenous addition of TNF-α promoted kidney inflammation, dramatic injury, and specific depletion of TNFRSF1A would abrogate the injury.ConclusionsThe single-cell profiling of AKI microenvironment provides new insight for the deep understanding of molecular changes of AKI, and elucidates the mechanisms and developing new targeted therapies for AKI.

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Background/Aims: Several pathological classification systems were commonly used in clinical practice to predict the prognosis of IgA nephropathy (IgAN). However, how prognostic value differs between these systems is unclear. The aim of this study was to compare the Lee grade, the Oxford classification, and the Haas classification and to find a simplified classification. Methods: We retrospectively analyzed IgAN cases diagnosed between January 2002 and December 2007. The endpoints were progression to end-stage renal disease (ESRD) or a ≥50% decline in estimated glomerular filtration rate (eGFR). The predictive capabilities were evaluated by comparing the ability of discrimination (continuous net reclassification) and calibration (Akaike information criterion [AIC]). Results: A total of 412 IgAN patients were included in the study. The average follow-up period was 80.62 ± 23.63 months. A total of 44 (10.68%) patients progressed to ESRD, and 70 (16.99%) patients showed a ≥50% decline in eGFR. All multivariate Cox regression models had limited power for high AIC values. The prognostic values of the Lee grade and the Oxford classification were higher than those of models containing only established baseline clinical indicators for progression to ESRD or a ≥50% decline in eGFR (Lee grade 0.50, 95% CI 0.21–0.74; Oxford classification 0.48, 95% CI 0.28–0.71). The prognostic value of the Haas classification was lower than that of the other pathological classification systems for progression to ESRD or a ≥50% decline in eGFR (Lee grade 0.53, 95% CI 0.23–0.92; Oxford classification 0.59, 95% CI 0.10–0.74). The prognostic value of hierarchical classification (Beijing classification) using M and T lesion was similar to the Oxford classification. Conclusions: Both the Lee grade and the Oxford classification showed incremental prognostic values beyond established baseline clinical indicators. The Haas classification was slightly inferior to the Lee grade and the Oxford classification. The hierarchical classification (Beijing classification) using less pathological parameters does not lose predictive efficiency.

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