Parkinson's disease (PD) is one of the common neurodegenerative diseases, with more than 10 million confirmed cases of PD estimated worldwide by 2040. 1 Tremor, rigidity, and bradykinesia are typical clinical manifestations of PD. 2 Non-motor symptoms include gastrointestinal dysfunction, such as constipation, sleep behavior disorder, depression, and cognitive impairment. 3 Importantly, nonmotor symptoms and motor symptoms might influence each other to aggravate PD severity, 4 thereby exacerbating the deterioration of quality of life and mentality in patients with PD.The pathogenesis of PD is complex, which is mainly related to complex environmental factors. A large number of epidemiological studies indicated that the prevalence of PD was higher in people over 50 years old, and the incidence increased with age. 5 The prevalence of PD was higher in men than that in women at the same age. 6 However, there were significant differences in PD prevalence among different regions and races in different studies. [7][8][9] In addition,
Edited by Roger J. Colbran The second messenger cyclic diguanylate (c-di-GMP) plays a prominent role in regulating flagellum-dependent motility in the single-flagellated pathogenic bacterium Pseudomonas aeruginosa. The c-di-GMP-mediated signaling pathways and mechanisms that control flagellar output remain to be fully unveiled. Studying surface-tethered and free-swimming P. aeruginosa PAO1 cells, we found that the overexpression of an exogenous diguanylate cyclase (DGC) raises the global cellular c-di-GMP concentration and thereby inhibits flagellar motor switching and decreases motor speed, reducing swimming speed and reversal frequency, respectively. We noted that the inhibiting effect of c-di-GMP on flagellar motor switching, but not motor speed, is exerted through the c-di-GMP-binding adaptor protein MapZ and associated chemotactic pathways. Among the 22 putative c-di-GMP phosphodiesterases, we found that three of them (DipA, NbdA, and RbdA) can significantly inhibit flagellar motor switching and swimming directional reversal in a MapZ-dependent manner. These results disclose a network of c-di-GMP-signaling proteins that regulate chemotactic responses and flagellar motor switching in P. aeruginosa and establish MapZ as a key signaling hub that integrates inputs from different c-di-GMP-signaling pathways to control flagellar output and bacterial motility. We rationalized these experimental findings by invoking a model that postulates the regulation of flagellar motor switching by subcellular c-di-GMP pools. Pseudomonas aeruginosa, a potentially lethal pathogenic bacterium for immune-compromised patients, relies on a sin-This work was supported by ARC Tier II Grant MOE2015-T2-2-026 (to Z.-X. L.) from the Ministry of Education of Singapore. The research is also supported by National Basic Research Program of China Program 973 Grant number 2015CB150600 (to L. X.) and Guangdong technological innovation strategy of special funds key areas of research and development program Grant 2018B020205003. The authors declare that they have no conflicts of interest with the contents of this article. This article contains Tables S1 and S2 and Figs. S1 and S2.
Parkinson's disease (PD) is the second most prevalent central nervous system (CNS) degenerative disease. Oxidative stress is one of key contributors to PD. Nuclear factor erythroid‐2‐related factor 2 (Nrf2) is considered to be a master regulator of many genes involved in anti‐oxidant stress to attenuate cell death. Therefore, activation of Nrf2 signalling provides an effective avenue to treat PD. Ellagic acid (EA), a natural polyphenolic contained in fruits and nuts, possesses amounts of pharmacological activities, such as anti‐oxidant stress and anti‐inflammation. Recent studies have confirmed EA could be used as a neuroprotective agent in neurodegenerative diseases. Here, mice subcutaneous injection of rotenone (ROT)‐induced DA neuronal damage was performed to investigate EA‐mediated neuroprotection. In addition, adult Nrf2 knockout mice and different cell cultures including MN9D‐enciched, MN9D‐BV‐2 and MN9D‐C6 cell co‐cultures were applied to explore the underlying mechanisms. Results demonstrated EA conferred neuroprotection against ROT‐induced DA neurotoxicity. Activation of Nrf2 signalling was involved in EA‐mediated DA neuroprotection, as evidenced by the following observations. First, EA activated Nrf2 signalling in ROT‐induced DA neuronal damage. Second, EA generated neuroprotection with the presence of astroglia and silence of Nrf2 in astroglia abolished EA‐mediated neuroprotection. Third, EA failed to produce DA neuroprotection in Nrf2 knockout mice. In conclusion, this study identified EA protected against DA neuronal loss via an Nrf2‐dependent manner.
Dyskinesia is a serious complication of Parkinson’s disease during levodopa (L-DOPA) treatment. The pathophysiology of L-DOPA-induced dyskinesia (LID) is complex and not fully illuminated. At present, treatment of dyskinesia is quite limited. Recent studies demonstrated neuroinflammation plays an important role in development of LID. Thus, inhibition of neuroinflammation might open a new avenue for LID treatment. Resveratrol (RES) is the most well-known polyphenolic stilbenoid and verified to possess a large variety of biological activities. DA neurotoxicity was assessed via behavior test and DA neuronal quantification. The movement disorders of dyskinesia were detected by the abnormal involuntary movements scores analysis. Effects of RES on glial cells-elicited neuroinflammation were also explored. Data showed that RES attenuated dyskinesia induced by L-DOPA without affecting L-DOPA’s anti-parkinsonian effects. Furthermore, RES generated neuroprotection against long term treatment of L-DOPA-induced DA neuronal damage. Meanwhile, RES reduced protein expression of dyskinesia molecular markers, ΔFOS B and ERK, in the striatum. Also, there was a strong negative correlation between DA system damage and ΔFOS B level in the striatum. In addition, RES inhibited microglia and astroglia activation in substantia nigra and subsequent inflammatory responses in the striatum during L-DOPA treatment. RES alleviates dyskinesia induced by L-DOPA and these beneficial effects are closely associated with protection against DA neuronal damage and inhibition of glial cells-mediated neuroinflammatory reactions.
Neuroinflammation plays a crucial role in the pathological process of Parkinson’s disease (PD). Nod-like receptor protein 3 (NLRP3) inflammasome was highly located in microglia and involved in the process of neuroinflammation. Activation of the NLRP3 inflammasome has been confirmed to contribute to the progression of PD. Thus, inhibition of NLRP3 inflammasome activation could be an important breakthrough point on PD therapy. Ellagic acid (EA) is a natural polyphenol that has been widely found in soft fruits, nuts, and other plant tissues with anti-inflammatory, antioxidant, and neuroprotective properties. However, the mechanisms underlying EA-mediated anti-inflammation and neuroprotection have not been fully elucidated. In this study, a lipopolysaccharide- (LPS-) induced rat dopamine (DA) neuronal damage model was performed to determine the effects of EA on the protection of DA neurons. In addition, the DA neuronal MN9D cell line and microglial BV-2 cell line were employed to explore whether EA-mediated neuroprotection was through an NLRP3-dependent mechanism. Results indicated that EA ameliorated LPS-induced DA neuronal loss in the rat substantia nigra. Further, inhibition of microglial NLRP3 inflammasome signaling activation was involved in EA-generated neuroprotection, as evidenced by the following observations. First, EA reduced NLRP3 inflammasome signaling activation in microglia and subsequent proinflammatory cytokines’ excretion. Second, EA-mediated antineuroinflammation and further DA neuroprotection from LPS-induced neurotoxicity were not shown upon microglial NLRP3 siRNA treatment. In conclusion, this study demonstrated that EA has a profound effect on protecting DA neurons against LPS-induced neurotoxicity via the suppression of microglial NLRP3 inflammasome activation.
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