The protection of NF-κB inhibition on kidney injury of systemic lupus erythematosus mice may be correlated with lncRNA TUG1

Abstract

We aimed to know the effect of nuclear factor-kappa B (NF-κB) inhibition on the kidney injury of systemic lupus erythematosus (SLE) mice. Pristane-induced SLE mice were treated with pyrrolidine dithiocarbamate (PDTC, 50 or 100 mg/kg), a NF-κB inhibitor. Histopathological changes were observed by hematoxylin & eosin, Masson and periodic schiff-methenamine stainings. Long noncoding RNA Taurine upregulated gene 1 (LncRNA TUG1) was measured by real-time reverse transcription PCR, NF-κB p65 expression by western blotting, levels of inflammatory cytokines, antinuclear antibodies (ANA), and antidouble stranded DNA (anti-dsDNA) by enzyme-linked immunosorbent assay, and the deposition of IgG and C3 by immunofluorescence. The kidney of SLE mice exhibited interstitial inflammatory cell infiltration, interstitial fibrous proliferation, glomerular mesangial proliferation, and crescent formation, which was mitigated after PDTC administration. The levels of BUN, Cr, ANA, and anti-dsDNA and the pro-inflammatory factors in SLE mice were increased with obvious deposition of IgG and C3, but they were also reversed by PDTC. Furthermore, the NF-κB p65 expression in the nucleus in the SLE mice was decreased with the up-regulation of TUG1 expression and NF-κB p65 expression in the cytoplasm after PDTC treatment. Correlation analysis revealed the negative correlation between the TUG1 expression and NF-κB p65 in the nucleus in the kidney tissues. NF-κB inhibition with PDTC protected against the kidney injury of pristine-induced SLE mice possibly via up-regulating lncRNA TUG1, and further clinical studies are needed to clarify whether NF-κB inhibition may be a therapeutic modality for the kidney injury of SLE.

Keywords: NF-κB pathway; PDTC; SLE; lncRNA TUG1.

Figure 1

The histopathological examination of kidney tissues in mice (×400)

Figure 2

Effect of NF‐κB inhibitor PDTC on biochemical and immunological indicators of kidney functions in SLE mice. Notes: A and B, Serum levels of blood urinary nitrogen (BUN, A) and creatinine (Cr, B) were detected in an automatic biochemical analyzer; C and D, Plasma levels of antinuclear antibody (ANA, ng/mL, C) and the anti‐double stranded DNA antibody (anti‐dsDNA, IU/mL, D) were measured by enzyme‐linked immunosorbent assay (ELISA). *, P < .05 compared with Control group; #P < .05 compared with SLE group; % P < .05 compared with SLE + 50 mg/kg PDTC group. NF‐κB, nuclear factor‐kappa B; PDTC, pyrrolidine dithiocarbamate; SLE, systemic lupus erythematosus

Figure 3

Effect of PDTC on the expressions of pro‐inflammatory factors (TNF‐α, IL‐6, MCP‐1, IL‐17A, IL‐1β, and IFN‐γ) detected by enzyme‐linked immunosorbent assay (ELISA) in the kidney tissues of SLE mice. Notes: #P < .05 compared with SLE group; % P < .05 compared with SLE + 50 mg/kg PDTC group. PDTC, pyrrolidine dithiocarbamate; SLE, systemic lupus erythematosus

Figure 4

Effect of PDTC on the deposition of IgG and C3 measured by immunofluorescence in the kidney tissues of SLE mice. Notes: A and B, Observation of the effect on the IgG deposition in the kidney of mice (IgG with the red fluorescence and nucleus with the blue fluorescence after DAPI staining); A and C, Observation of the effect on the complement C3 deposition in the kidney of mice (C3 with the green fluorescence and nucleus with the blue fluorescence after DAPI staining). #P < .05 compared with SLE group; % P < .05 compared with SLE + 50 mg/kg PDTC group. PDTC, pyrrolidine dithiocarbamate; SLE, systemic lupus erythematosus

Figure 5

Comparison of the expressions of NF‐κB p65 and lncRNA TUG1 in the kidney tissues in mice among groups. Notes: A and B, Expression of NF‐κB p65 in the nucleus and cytoplasm in the kidney tissues of mice detected by western blotting, 1, control group, 2, SLE group, 3, SLE + 50 mg/kg PDTC group, and 4, SLE + 100 mg/kg PDTC group; C, TUG1 expression in mice by qRT‐PCR; D, The correlation analysis between the TUG1 expression and NF‐κB p65 in the nucleus in the kidney tissues of mice. #P < .05 compared with SLE group; % P < .05 compared with SLE + 50 mg/kg PDTC group. NF‐κB, nuclear factor‐kappa B; PDTC, pyrrolidine dithiocarbamate; qRT‐PCR, real‐time reverse transcription PCR; SLE, systemic lupus erythematosus