Résumé
Background: Microglial cells act as the sentinel of the central nervous system. They are involved in neuroprotection but are highly implicated in neurodegeneration of the aging brain. When over-activated, microglia release pro-inflammatory factors, such as nitric oxide [NO] and cytokines, which are critical in eliciting neuroinflammatory responses associated with neurodegenerative diseases. This study examined whether bromelain, the pineapple-derived extract, may exert an anti-inflammatory effect in primary microglia and may be neuroprotective by regulating microglial activation.
Methods: Following the isolation of neonatal rat primary microglial cells, the activation profile of microglia was investigated by studying the effects of bromelain [5, 10, 20, and 30 ng/ml] on the levels of NO, inducible nitric oxide synthase [iNOS], and nuclear factor kappa B [NF-KB] in microglia treated with lipopolysaccharide [LPS] [1 ng/ml]. Data were analyzed using Student's t-test. P values less than 0.05 were considered to be statistically significant, compared with the LPS-treated group without bromelain
Results: Results showed that pretreatment of rat primary microglia with bromelain, decreased the production of NO induced by LPS [1 u,g/ml] treatment in a dose-dependent manner. Bromelain [30 micro.g/ml] also significantly reduced the expression of iNOS at mRNA level and NF-KB at protein level. Moreover, the study of mitochondrial activity in microglia indicated that bromelain had no cytotoxicity at any of the applied doses, suggesting that the anti-inflammatory effects of bromelain are not due to cell death
Conclusion: Bromelain can be of potential use as an agent for alleviation of symptoms in neurodegenerative diseases