SIRT3 retards intervertebral disc degeneration by anti-oxidative stress by activating the SIRT3/FOXO3/SOD2 signaling pathway.

OBJECTIVE: The objective of this paper is to determine whether SIRT3 could retard intervertebral disc degeneration and study the mechanism. MATERIALS AND METHODS: We chose the 3-month mice to establish intervertebral disc degeneration model and study the effect of SIRT3 on the intervertebral disc by Western blotting, quantitative Real Time-Polymerase Chain Reaction (qRT-PCR), immunohistochemistry. Mouse nucleus pulposus cells were cultured to study the exact mechanism. RESULTS: The expression of SIRT3 was decreased in degenerated human nucleus pulposus. Intervertebral discs of mice treated with theacrine expressed more collagen II and less collagen X. In addition, nucleus pulposus cells stimulated with interleukin-1ß (IL-1ß) expressed less SIRT3 than that in the control group and nucleus pulposus cells with SIRT3 overexpress vectors expressed more collagen II FOXO3a and superoxide dismutase 2 (SOD2), indicating that SIRT3 could improve the intervertebral disc degeneration by anti-oxidative stress. CONCLUSIONS: SIRT3 is a protective factor for intervertebral discs and can reduce oxidative stress in the intervertebral disc.

[Effect and mechanism of MicroRNA-146a on TLR4 inflammatory signal pathway in the lung tissues of rats with mechanical ventilator-induced lung injury].

Objective: To investigate the effect and mechanism of microRNA-146a (miR-146a) on Toll-Like Receptor 4 (TLR4) inflammatory signal pathway in the lung tissues of rats with mechanical ventilator-induced lung injury. Methods: Thirty-two healthy male Sprague-Dawley rats were randomly divided into 4 groups (n=8 each): group A, normal control group, no mechanical ventilation, spontaneous breathing; group B, mechanical ventilation injury; group C, mechanical ventilation injury plus no-load virus transfection; group D, mechanical ventilation injury plus virus transfection; in group B, C, and D, mechanical ventilation were performed, respiratory rate was controlled at 80 beats/min, tidal volume was 40 ml/kg, inhaled oxygen concentration (FiO2) was 21%, inhalation/expiration ratio was 1∶2, positive end expiratory pressure ventilation (PEEP) was 0, each group were ventilated 4 hours daily, 7 days continuously to establish ventilator induced lung injury (VILI) rat model. Paraffin-embedded sections of lung tissue were stained with HE, the morphology and damage of lung tissue were observed under microscope. The lungs wet and dry ratio (W/D), the levels of inflammatory cytokines interleukin (IL)-1ß, IL-2 and tumor necrosis factor (TNF)-α were determined. Real-time PCR was used to detect the expression of TLR4 mRNA. The level of TLR4 protein was determined by Western blot. Results: The levels of lung tissue W/D and lung injury scores in group B (6.41±0.10, 11.38±0.92), group C (6.45±0.19, 11.75±1.04), group D (5.95±0.14, 7.53±4.78) were significantly increased than those in group A (4.33±0.08, 0.25±0.46), and in group D they were significantly decreased than group C (all P<0.01). The levels of IL-1ß, IL-2, TNF-α in group B[(36.07±4.28) pg/ml, (5.02±0.63) ng/ml, (382.57±35.41) ng/ml], group C[(35.82±5.47) pg/ml, (4.98±0.71) ng/ml, (375.13±36.95) ng/ml], group D[(27.01±3.18) pg/ml, (3.96±0.82) ng/ml, (297.56±39.08) ng/ml]were significantly increased than those in group A[(21.46±3.15) pg/ml, (2.45±0.17) ng/ml, (195.92±18.07) ng/ml], and in group D they were significantly decreased than group C (all P<0.01). The relative expression levels of TLR4 mRNA and TLR4 proteins in group B (29.57±5.10, 0.75±0.110), group C (27.27±4.72, 0.77±0.130), group D (12.89±2.58, 0.48±0.057) were significantly increased than those in group A (1.02±0.13, 0.18±0.025), and in group D they were significantly decreased than group C (all P<0.01). There was no significant difference of all the above indicators between group B and C (all P>0.05). Conclusions: MiR-146a can reduce acute lung inflammation and TLR4 expression in lungs of rats with mechanical ventilator-induced lung injury. MiR-146a may inhibit the inflammatory response through TLR4 signaling pathway.