Related Experiment Video
Updated: May 24, 2026
A Quantitative Detection Method for MicroRNAs in the Kidney of an Ischemic Kidney Injury Mouse Model
Published on: September 11, 2020
The Positive Feedback Regulation of NF-κB/miR-21c/IL-9 Axis in Septic Acute Kidney Injury
Zheng Li1, Juan Wang2, Lei Zhang1
1Department of Nephrology, The Second Xiangya Hospital at Central South University, Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, Hunan, China.
Key Points:
Our study identifies a pathogenic NF-κB/microRNA-21c/IL-9 feedback loop that amplifies renal inflammation and injury in sepsis-associated AKI. MicroRNA-21c was significantly upregulated in renal proximal tubules during LPS-induced sepsis-associated AKI.
Background:
Sepsis-associated AKI (septic AKI) is a leading cause of mortality in critically ill patients. Despite its high prevalence, no specific therapies are currently available, primarily because the molecular mechanisms that sustain renal inflammation and tubular damage remain poorly understood.
Methods:
A murine model of LPS-induced septic AKI and cultured murine proximal tubular (Boston University mouse proximal tubular) cells were used. In vivo , anti-microRNA-21c (miR-21c) or miR-21c mimic was administered through tail vein injection before LPS challenge. Molecular interactions were assessed by chromatin immunoprecipitation, luciferase reporter assay, quantitative PCR, Western blotting, immunohistochemistry, and fluorescence in situ hybridization. Renal function and injury were evaluated by serum creatinine, BUN, histopathology, and terminal deoxynucleotidyl transferase-mediated digoxigenin-deoxyuridine nick-end labeling staining.
Results:
miR-21c was significantly upregulated in renal proximal tubules during LPS-induced septic AKI, coinciding with peak renal dysfunction and tubular damage. This upregulation was driven by NF-κB because LPS induced p65 nuclear translocation, and pharmacologic inhibition of NF-κB blocked miR-21c induction. Chromatin immunoprecipitation assays confirmed direct binding of p65 to the miR-21c promoter. Subsequent dual-luciferase reporter assays specifically validated the binding site as the functional response element. Functional studies showed that inhibition of miR-21c attenuated kidney injury, reducing serum creatinine and BUN levels, alleviating histological damage, decreasing tubular apoptosis, and suppressing proinflammatory cytokines. Conversely, overexpression of miR-21c exacerbated all injury parameters. Mechanistically, miR-21c directly targeted the 3'-untranslated region of IL-9, as validated by luciferase reporter assay, resulting in reduced IL-9 protein expression. Restoration of IL-9 in tubular cells suppressed LPS-induced apoptosis and inflammation. Importantly, IL-9 overexpression specifically inhibited phosphorylation of NF-κB p65.
Conclusions:
Our study identified a pathogenic NF-κB/miR-21c/IL-9 feedback loop that amplified renal inflammation and injury in septic AKI. Targeting miR-21c or enhancing IL-9 signaling may offer novel therapeutic strategies to mitigate kidney damage and improve outcomes in septic patients.
Insights
A novel NF-κB/miR-21c/IL-9 feedback loop drives kidney inflammation and injury in sepsis-associated acute kidney injury (septic AKI). Targeting miR-21c or boosting IL-9 may offer new therapies for septic AKI.
Area of Science:
- Nephrology
- Molecular Biology
- Immunology
Background:
- Sepsis-associated acute kidney injury (septic AKI) is a major cause of death in critically ill patients.
- Current treatments for septic AKI are limited due to poor understanding of the underlying molecular mechanisms.
- Renal inflammation and tubular damage are key pathological features of septic AKI.
Purpose of the Study:
- To elucidate the molecular mechanisms driving renal inflammation and injury in septic AKI.
- To identify potential therapeutic targets for mitigating kidney damage in septic AKI.
Main Methods:
- Utilized a murine model of LPS-induced septic AKI and cultured proximal tubular cells.
- Investigated the role of miR-21c and its regulation by NF-κB.
- Assessed the interaction between miR-21c and interleukin-9 (IL-9) using molecular biology techniques.
- Evaluated the effects of modulating miR-21c and IL-9 on kidney function and injury markers.
Main Results:
- miR-21c was upregulated in septic AKI kidneys, driven by NF-κB activation.
- Inhibition of miR-21c attenuated kidney injury, reduced inflammation, and decreased tubular apoptosis.
- miR-21c directly targeted IL-9, and IL-9 restoration suppressed LPS-induced injury.
- IL-9 overexpression inhibited NF-κB p65 phosphorylation, suggesting a feedback loop.
Conclusions:
- Identified a pathogenic NF-κB/miR-21c/IL-9 feedback loop that exacerbates septic AKI.
- Targeting miR-21c or enhancing IL-9 signaling presents promising therapeutic strategies for septic AKI.
- This discovery could lead to improved treatment outcomes for patients with septic AKI.
Related Concept Videos
01:29Acute Kidney Injury II: Pathophysiology
02:26NF-κB-dependent Signaling Pathway
NF-κB-dependent Signaling Mechanism
The heterodimer of NF-κB...
01:22Acute Kidney Injury I: Introduction
01:29Acute Kidney Injury III: Clinical Manifestations
01:22Acute Kidney Injury VI: Nursing Management
01:30Acute Kidney Injury IV: Diagnostic Studies and Prevention