Therefore, TPM and LEV might have the potential to treat AD effectively in patient care.

BackgroundNumerous studies suggested that PM2.5 exposure was associated with increased risk of Alzheimer’s disease (AD). But the precise mechanisms by which PM2.5 contributed to AD pathogenesis have not been clarified.MethodsIn the presence or absence of neurons, oligomeric amyloid beta (oAβ)-primed microglia were stimulated with PM2.5. Firstly, we determined the effects of PM2.5 exposure on neuronal injury and inflammation in neurons-microglia co-cultures. Then, we examined whether NLRP3 inflammasome activation was involved in PM2.5-induced inflammation. After that, we investigated whether PM2.5 exposure increased ROS level in oAβ-stimulated microglia. At last, we examined whether ROS and NLRP3 inflammasome activation was required for PM2.5-induced neuronal injury in neurons-microglia co-cultures.ResultsIn the present study, we showed that PM2.5 exposure aggravated oAβ-induced neuronal injury and inflammation in neurons-microglia co-cultures via increasing IL-1β production. Further, PM2.5-induced IL-1β production in oAβ-stimulated microglia was possibly dependent on NLRP3 inflammasome activation. Meanwhile, PM2.5 exposure increased ROS level in oAβ-stimulated microglia. ROS was required for PM2.5-induced IL-1β production and NLRP3 inflammasome activation in oAβ-stimulated microglia. More importantly, ROS and NLRP3 inflammasome activation was required for PM2.5-induced neuronal injury in neurons-microglia co-cultures.ConclusionsFor the first time, these results suggested that the effects of PM2.5 under AD context were possibly mediated by NLRP3 inflammasome activation, which was triggered by ROS. Taken together, these findings have deepened our understanding on the role of PM2.5 in AD pathogenesis.

As a recently identified bioactive peptide of brain renin-angiotensin system (RAS), angiotensin-(1-7) [Ang-(1-7)] along with its metabolic enzyme angiotensin-converting enzyme (ACE) 2 and its receptor Mas forms ACE2/Ang-(1-7)/Mas axis. Accumulating evidence suggests an essential role of ACE2/Ang-(1-7)/Mas axis in maintaining normal cognitive functions in both animals and human subjects, and dysregulation of this axis contributed to the pathogenesis of several neurodegenerative diseases such as hypertension-induced neurodegeneration and vascular dementia. To date, whether this axis was associated with the etiology and progression of Alzheimer's disease (AD), the most prevalent neurodegenerative disease in the elderly, remains unclear. In the current study, by using senescence-accelerated mouse prone 8 (SAMP8) mice, an animal model of sporadic AD, we showed for the first time that the level of Ang-(1-7) in the brain was significantly reduced during disease progression. More importantly, an inverse correlation was found between Ang-(1-7) level and tau hyperphosphorylation, a pathological hallmark of AD, in cerebral cortex and hippocampus of SAMP8 mice. Meanwhile, this has been further confirmed in P301S mice, an animal model of pure tauopathy. All these findings suggested that Ang-(1-7), the main effector of brain ACE2/Ang-(1-7)/Mas axis, might be implicated in the etiology and progression of AD, possibly via modulation of tau hyperphosphorylation.

No abstract

No abstract