Long Non-coding RNA NEAT1 , NOD-Like Receptor Family Protein 3 Inflammasome, and Acute Kidney Injury.

Abstract

Long non-coding RNA (lncRNA) nuclear-enriched abundant transcript 1 (<i>NEAT1</i>) was upregulated in human and murine AKI. It returned to baseline after recovery in humans. Its knockdown preserved kidney function in animals. <i>In vitro</i>, LPS upregulated <i>NEAT1</i> by TLR4/NF-κB signaling and caused its translocation into the cytoplasm where it activated nucleotide oligomerization domain-like receptor family protein 3 by binding receptor of activated protein C kinase 1. AKI is common in hospitalized patients and is associated with high mortality. Inflammation plays a key role in the pathophysiology of AKI. Long non-coding RNAs (lncRNAs) are increasingly recognized as regulators of the inflammatory and immune response, but its role in AKI remains unclear. We explored the role of lncRNA nuclear-enriched abundant transcript 1 (<i>NEAT1</i>) in (<i>1</i>) a cross-sectional and longitudinal cohort of AKI in humans, (<i>2</i>) three murine models of septic and aseptic AKI, and (<i>3</i>) cultured C1.1 mouse kidney tubular cells. In humans, hospitalized patients with AKI (<i>N</i>=66) demonstrated significantly higher lncRNA <i>NEAT1</i> levels in urinary sediment cells and buffy coat versus control participants (<i>N</i>=152) from a primary care clinic; among six kidney transplant recipients, <i>NEAT1</i> levels were the highest immediately after transplant surgery, followed by a prompt decline to normal levels in parallel with recovery of kidney function. In mice with AKI induced by sepsis (by LPS injection or cecal ligation and puncture) and renal ischemia-reperfusion, kidney tubular <i>Neat1</i> was increased versus sham-operated mice. Knockdown of <i>Neat1</i> in the kidney using short hairpin RNA preserved kidney function and suppressed overexpression of the AKI biomarker neutrophil gelatinase-associated lipocalin, leukocyte infiltration, and both intrarenal and systemic inflammatory cytokines IL-6, CCL-2, and IL-1<i>β</i>. In LPS-treated C1.1 cells, <i>Neat1</i> was overexpressed by TLR4/NF-κB signaling and translocated from the cell nucleus into the cytoplasm where it promoted activation of nucleotide oligomerization domain-like receptor family protein 3 inflammasomes by binding with the scaffold protein receptor of activated protein C kinase 1. Silencing <i>Neat1</i> ameliorated LPS-induced cell inflammation, whereas its overexpression upregulated IL-6 and CCL-2 expression even without LPS stimulation. Our findings demonstrate a pathogenic role of <i>NEAT1</i> induction in human and mice during AKI with alleviation of kidney injury in three experimental models of septic and aseptic AKI after knockdown of <i>Neat1</i>. LPS/TLR4-induced <i>Neat1</i> overexpression in tubular epithelial cells increased the inflammatory response by binding with the scaffold protein, receptor of activated protein C kinase 1, to activate nucleotide oligomerization domain-like receptor family protein 3 inflammasomes.