Downregulation of cystathionine ß-synthase/hydrogen sulfide contributes to rotenone-induced microglia polarization toward M1 type.

Microglia-mediated neuroinflammation is implicated in the pathogenesis of several neurodegenerative disorders. Microglia can be activated and polarized to exert pro- or anti-inflammatory roles in response to specific stimulus. Rotenone is an environmental toxin that has been shown to activate microglia and neuroinflammation. However, the effects and mechanisms of rotenone on microglia polarization are poorly studied. In the present study, we demonstrated that rotenone enhanced the levels of M1 phenotypic genes including TNF-α, iNOS and COX-2/PGE2 but reduced that of M2 markers such as Ym1/2 and IL-10 in mouse primary and immortalized microglia. Moreover, the transcription and protein expression of cystathionine-ß-synthase (CBS), as well as hydrogen sulfide (H2S) production were decreased in rotenone-treated primary microglia. Elevating endogenous H2S via CBS over-expression in immortalized microglia not only reduced the expression of pro-inflammatory M1 genes, but also enhanced the anti-inflammatory M2 marker IL-10 production in response to rotenone stimulation as compared to vector-transfected cells. Similarly, pretreatment with H2S donor NaHS (50, 100 and 500µmol/L) attenuated the increases of M1 gene expression triggered by rotenone treatment, and enhanced the M2 gene Ym1/2 expression in mouse primary microglia. In addition, we observed reactive oxygen species (ROS) scavenger N-acetyl-l-cysteine reversed the down-regulation of CBS and H2S generation caused by rotenone in microglia. NaHS pretreatment also decreased the ROS formation in rotenone-stimulated microglia. Taken together, these results reveal that probably via triggering ROS formation, rotenone suppressed the CBS-H2S pathway and thus promoted microglia polarization toward M1 pro-inflammatory phenotype.

Increased Serum Cystatin C in Early Parkinson's Disease with Objective Sleep Disturbances.

BACKGROUND: Sleep disturbance is one of the major non-motor symptoms which cause the disability of Parkinson's disease (PD) patients. Cystatin C (CysC) is a more sensitive biomarker than serum creatinine or estimated glomerular filtration rate. Previous studies have reported altered CysC levels in neurodegenerative disorders and sleep disorders. This study aimed to explore the correlations of serum CysC levels and objective sleep disturbances in early PD. METHODS: We recruited 106 early PD patients and 146 age- and sex-matched controls. All participants underwent clinical investigation and video-polysomnography. Sleep parameters and serum levels of CysC were measured. Then, we investigated the relationships between CysC and clinical variables and objective sleep disturbances in early PD patients. RESULTS: The mean serum level of CysC was significantly higher in patients with early PD (1.03 ± 0.19 mg/L) compared to controls (0.96 ± 0.15 mg/L, P = 0.009). There were significantly positive correlations between serum CysC levels and age (r = 0.334, P < 0.001), gender (r = 0.264, P = 0.013), and creatinine levels (r = 0.302, P = 0.018) in early PD patients. Increased serum CysC levels in early PD patients were significantly associated with higher apnea and hypopnea index (AHI) (r = 0.231, P = 0.017), especially hypopnea index (r = 0.333, P < 0.001). In early PD patients, elevated serum CysC levels were positively correlated with oxygen desaturation index (r = 0.223, P = 0.021), percentage of time spent at oxygen saturation (SaO2) <90% (r = 0.644, P < 0.001), arousal with respiratory event during sleep (r = 0.247, P = 0.013). On the contrary, the elevated serum CysC levels were negatively correlated with mean and minimal SaO2(r = -0.323, -0.315, both P = 0.001) in PD patients. CONCLUSIONS: The level of serum CysC was higher in early PD patients. PD patients with elevated serum CysC levels had more respiratory events and more severe oxygen desaturation. Therefore, the serum CysC levels may predict the severities of sleep-disordered breathing problems in early PD patients.