Emerging microRNA biomarkers for acute kidney injury in acute decompensated heart failure

lncRNA NORAD alleviates dysfunction of renal proximal tubular epithelial cells during the sepsis-associated acute kidney injury by modulating the miR-155-5p-PDK1 axis

The sepsis-associated acute kidney injury (Sa-AKI) is closely related to high mortality rates worldwide. Injury to the renal proximal tubular epithelial cells (RPTECs), caused by pathological conditions, is a major cause of acute kidney injury (AKI). The lncRNA NORAD has been reported to be positively associated with kidney cancers. However, the biological roles and underlying mechanisms of NORAD in RPTECs during AKI are still unclear. In this study, we found that NORAD was significantly downregulated in RPTECs from AKI tissues. Overexpression of NORAD alleviated RPTECs injury induced by lipopolysaccharide (LPS). Additionally, glucose metabolism was significantly impaired during AKI, and LPS treatment inhibited glucose metabolism in RPTECs. We demonstrated that NORAD rescued the LPS-induced inhibition of glucose metabolism in RPTECs. Furthermore, miRNA-155-5p was significantly upregulated in RPTECs from AKI. Through bioinformatics analysis, RNA pull-down, RNA IP, and luciferase assays, we showed that NORAD directly associated with miR-155-5p to downregulate its expression. Moreover, overexpression of miR-155-5p inhibited glucose metabolism by directly targeting the 3'UTR of the glucose metabolism enzyme, pyruvate dehydrogenase kinase 1 (PDK1). Finally, rescue experiments validated that NORAD's protective effect on RPTECs injury was mediated through modulation of the miR-155-5p-PDK1-glucose metabolism pathway. In summary, these results reveal that lncRNA NORAD can alleviate RPTECs dysfunction by targeting the miR-155-5p-PDK1 axis, suggesting that NORAD has the potential to contribute to the development of therapeutic approaches against Sa-AKI.

Time-sensitive approach in the management of acute heart failure

Acute heart failure (AHF) has become a global public health burden largely because of the associated high morbidity, mortality, and cost. The treatment options for AHF have remained relatively unchanged over the past decades. Historically, clinical congestion alone has been considered the main target for treatment of acute decompensation in patients with AHF; however, this is an oversimplification of the complex pathophysiology. Within the similar clinical presentation of congestion, significant differences in pathophysiological mechanisms exist between the fluid accumulation and redistribution. Tissue hypoperfusion is another vital characteristic of AHF and should be promptly treated with appropriate interventions. In addition, recent clinical trials of novel therapeutic strategies have shown that heart failure management is ‘time sensitive’ and suggested that treatment selection based on individual aetiologies, triggers, and risk factor profiles could lead to better outcomes. In this review, we aim to describe the specifics of the ‘time‐sensitive’ approach by the clinical phenotypes, for example, pulmonary/systemic congestion and tissue hypoperfusion, wherein patients are classified based on pathophysiological conditions. This mechanistic classification, in parallel with the comprehensive risk assessment, has become a cornerstone in the management of patients with AHF and thus supports effective decision making by clinicians. We will also highlight how therapeutic modalities should be individualized according to each clinical phenotype.