C1q/tumor necrosis factor‐related protein‐3 improves renal fibrosis via inhibiting notch signaling pathways

Angiotensin II upregulates tumor necrosis factor-α (TNF-α) in the rat kidney with unilateral ureteral obstruction (UUO). In a mouse model of UUO, we found that tubulointerstitial fibrosis is blunted when the TNF-α receptor, TNFR1, is functionally knocked out. In this study, we used mutant mice with UUO in which the angiotensin II receptor AT1a or the TNF-α receptors TNFR1 and TNFR2 were knocked out to elucidate interactions between the two systems. The contribution of both systems to renal fibrosis was assessed by treating TNFR1/TNFR2-double knockout (KO) mice with an angiotensin-converting enzyme inhibitor, enalapril. The increased interstitial volume (Vvint) in the C57BI/6 wild-type mouse was decreased in the AT1a KO from 32.8 ± 4.0 to 21.0 ± 3.7% ( P < 0.005) or in the TNFR1/TNFR2 KO to 22.3 ± 2.1% ( P < 0.005). The Vvint of the TNFR1/TNFR2 KO was further decreased to 15.2 ± 3.7% ( P < 0.01) by enalapril compared with no treatment. The induction of TNF-α mRNA and transforming growth factor-β1 (TGF-β1) mRNA in the kidney with UUO was significantly blunted in the AT1a or TNFR1/TNFR2 KO mice compared with the wild-type mice. Treatment of the TNFR1/TNFR2 KO mouse with enalapril reduced both TNF-α and TGF-β1 mRNA and their proteins to near normal levels. Also, α-smooth muscle actin expression and myofibroblast proliferation were significantly inhibited in the AT1a or TNFR1/TNFR2 KO mice, and they were further inhibited in enalapril-treated TNFR1/TNFR2 KO mice. Incapacitating the angiotensin II or the TNF-α systems individually leads to partial blunting of fibrosis. Incapacitating both systems, by using a combination of genetic and pharmacological means, further inhibited interstitial fibrosis and tubule atrophy in obstructive nephropathy.

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Alpha-Lipoic Acid Suppresses Extracellular Histone-Induced Release of the Infammatory Mediator Tumor Necrosis Factor-α by Macrophages

Cellular Physiology and Biochemistry ◽

10.1159/000480217 ◽

2017 ◽

Vol 42 (6) ◽

pp. 2559-2568 ◽

Cited By ~ 3

Author(s):

Ping Chang ◽

Juan Liu ◽

Ying Yu ◽

Shao-Ye Cui ◽

Zhen-Hui Guo ◽

...

Keyword(s):

Tumor Necrosis Factor ◽

Signaling Pathways ◽

Tumor Necrosis ◽

Tumor Necrosis Factor Α ◽

Raw 264.7 ◽

Alpha Lipoic Acid ◽

Tnf Α ◽

Extracellular Histones ◽

Factor Α ◽

Necrosis Factor

Background/Aims: This study investigated signaling pathways via which extracellular histones induce the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) release from the macrophage cell line RAW 264.7 and the anti-inflammatory efficacy of the antioxidant alpha-lipoic acid (ALA). Methods: ELISA and western blotting analyses were conducted to detect the release of TNF-α from histone-stimulated RAW 264.7 macrophages and the associated phospho-activation of MAPKs (ERK and p38) and NF-κB p65. The effects of ALA on the release of TNF-α and phospho-activation of the MAPKs and NF-κB p65 were studied. P < 0.05 was considered statistically significant. Results: Extracellular histones dose-dependently induced TNF-α release from RAW 264.7 cells and increased the phosphorylation of p38, ERK, and NF-κB p65. TNF-α release was markedly suppressed by p38, ERK, and NF-kB inhibitors. ALA reduced histone-induced TNF-α release, ERK/p38 MAPK activation, and NF-kB activation without affecting macrophage viability. Conclusion: Histones induce TNF-α release from macrophages by activating the MAPK and NF-kB signaling pathways, while ALA suppresses this response by inhibiting ERK, p38 and NF-kB. These findings identify potentially critical inflammatory signaling pathways in sepsis and molecular targets for sepsis treatment.

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