SIRT3 expression alleviates microglia activation­induced dopaminergic neuron injury through the mitochondrial pathway.

The mitochondrial protein sirtuin 3 (SIRT3) can counteract cell damage caused by oxidative stress and inflammation, and contribute to cell survival primarily by improving mitochondrial function. However, the effects of SIRT3 in dopaminergic neuronal cells (DACs) remain unclear. In our previous studies, microglia activation-associated cytotoxicity was observed to promote the apoptosis of DACs, along with the decrease of SIRT3 expression. The aim of the present study was to explore the potential neuroprotective effect of SIRT3 expression against dopaminergic neuron injury caused by microglia activation, and clarify its possible mechanisms. SIRT3 overexpression in DACs reduced the production of intracellular reactive oxygen species (ROS), cell apoptosis rate, mitochondrial membrane potential (ΔΨm) depolarization, opening of mitochondrial permeability transition pore (mPTP) and cyclophilin D (CypD) protein level, and promoted cell cycle progression. However, SIRT3 siRNA-mediated knockdown further aggravated microglia activation-mediated cytotoxicity, including ROS accumulation, increased cell apoptosis and mPTP opening, elevated the CypD level, enhanced mitochondrial ΔΨm depolarization, concomitant to cell cycle arrest at G0/G1 phase. The mechanisms of SIRT3 mitigated microglia activation-induced DAC dysfunction, which included decreased mPTP opening and Bax/Bcl-2 ratio, inhibition of mitochondrial cytochrome c release to the cytoplasm, reduced caspase-3/9 activity, increased LC3II/LC3I and beclin-1 protein expression levels, and decreased nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain-containing protein 3 (NLRP3), caspase-1, IL-1ß and IL-18 protein expression. In conclusion, these results indicated that SIRT3 expression attenuated cell damage caused by microglia activation through the mitochondrial apoptosis pathway in DACs. The mitophagy-NLRP3 inflammasome pathway may also be associated with this neuroprotection. These findings may provide new intervention targets for the survival of dopaminergic neurons and the prevention and treatment of Parkinson's disease.

Efficacy and safety of combination therapy with pramipexole and levodopa vs levodopa monotherapy in patients with Parkinson disease: A systematic review and meta-analysis.

BACKGROUND: Pramipexole (P) or levodopa (L) treatment has been suggested as a therapeutic method for Parkinson disease (PD) in many clinical studies. Nonetheless, the combined effects of 2 drugs for PD patients are not completely understood.The aim of this research was to evaluate the clinical efficacy and safety of P plus L (P+L) combination therapy in the treatment of PD compared to that of L monotherapy, in order to confer a reference for clinical practice. METHODS: Randomized controlled trials (RCTs) of P+L for PD published up to April, 2020 were retrieved. Standardized mean difference (SMD), odds ratio (OR), and 95% confidence interval (CI) were calculated and heterogeneity was measured with the I2 test. Sensitivity analysis was also carried out. The outcomes of interest were as follows: the efficacy, unified Parkinson disease rating scale (UPDRS) scores, Hamilton depression rating scale score or adverse events. RESULTS: Twenty-four RCTs with 2171 participants were included. Clinical efficacy of P+L combination therapy was significantly better than L monotherapy (9 trials; OR 4.29, 95% CI 2.78 to 6.64, P < .00001). Compared with L monotherapy, the pooled effects of P+L combination therapy on UPDRS score were (22 trials; SMD -1.31, 95% CI -1.57 to -1.04, P < .00001) for motor UPDRS score, (16 trials; SMD -1.26, 95% CI -1.49 to -1.03, P < .00001) for activities of daily living UPDRS score, (12 trials; SMD -1.02, 95% CI -1.27 to -0.77, P < .00001) for mental UPDRS score, (10 trials; SMD -1.54, 95% CI -1.93 to -1.15, P < .00001) for complication UPDRS score. The Hamilton depression rating scale score showed significant decrease in the P+L combination therapy compared to L monotherapy (12 trials; SMD -1.56, 95% CI -1.90 to -1.22, P < .00001). In contrast to L monotherapy, P+L combination therapy reduced the number of any adverse events obviously in PD patients (16 trials; OR 0.36, 95% CI 0.27 to 0.50, P < .00001). CONCLUSIONS: P+L combination therapy is superior to L monotherapy for improvement of clinical symptoms in PD patients. Moreover, the safety profile of P+L combination therapy is better than that of L monotherapy. Further well-designed, multicenter RCTs needed to identify these findings.

Constituents from Polygonatum sibiricum and their inhibitions on the formation of advanced glycosylation end products.

A new saponin, isonarthogenin 3-O-ß-d-glucopyranosyl-(1→4)-ß-d-galactopyranoside (1), together with twelve known compounds, were isolated from the rhizomes of Polygonatum sibiricum. The structures of these compounds were elucidated by analysis of their 1D/2D NMR and MS data. Among them, phenol compounds 4-7 and 9-10 showed significant inhibitions against the formation of advanced glycosylation end products, with IC50 values of 0.091 ± 0.0021, 0.10 ± 0.041, 0.014 ± 0.0027, 0.11 ± 0.011, 0.13 ± 0.045, and 0.055 ± 0.019 µM, respectively. The results will promote exploiting potential medicinal use of these compounds in the prevention of diabetic complications and supporting Polygonatum sibiricum as a functional food for healthy and medicinal diet.