From systematic review to network pharmacology : evidence based medicine-guided mechanistic study for Bao Yuan decoction against cerebral ischemia-reperfusion injury

Abstract

Stroke is the second leading cause of death, with the majority of cases being ischemic stroke. More and more onsets occur among young adults nowadays. This could impose a big impact to the wellbeing of individuals as well as their families, and burden the socio-economic development of countries. Conventional treatment strategies focus on getting rid of the blood clot, which prevents blood from circulating to the brain. Reperfusion, however, may bring along additional brain injury. Besides, conventional drugs such as tissue type plasminogen activator (t-PA), impose life threatening side effects onto patients. It is therefore very essential to develop a drug that is safe to use and is able to provide good prognosis. Bao Yuan Decoction (BY) is a patented Chinese medicinal formula composing of four herbs. Through exploring the mechanistic actions of BY in acting against cerebral ischemia-reperfusion injury, this study serves as a validation of methodology that the findings obtained from systematic reviews and network pharmacology could be verified by experiments in the laboratory. A series of four systematic reviews to evaluate the effects against cerebral ischemic stroke in the four herbs composing BY was conducted. Eligible in vivo and in vitro studies were identified from literature databases based on inclusive and exclusive criteria. Methodological quality assessment, risk of bias, quantitative synthesis, sensitivity analysis and publication bias analysis were performed. Network pharmacology analysis including druggability analysis, enrichment analyses on chemical-gene interaction and chemical-protein interaction were carried out to predict the potential signalling pathways of BY. Extent of neurological severity [expressed in terms of neurological severity scores] and cerebral infarct size [using 2,3,5-triphenyl-tetrazoliumchloride (TTC) staining] were evaluated in middle cerebral artery occlusion (MCAO) rats treated with BY, comparing with MCAO rats without treatment. Mechanistic actions of BY based on the prediction made from network pharmacology analysis were verified through Western blot analysis.

Outcomes of systematic reviews indicate that respective herbs in BY are anti-oxidative, anti-inflammatory and/or anti-apoptotic. Experiment results reveal that BY significantly minimized the cerebral infarct size and reduced the extent of neurological severity. Neuroprotective effects of BY were attributed to its anti-inflammatory, anti-oxidative and anti-apoptotic functions. BY inhibited the activity of TLR2, and down-regulated the expressions of iNOS, COX2 and TNFα along HIF-1 signalling pathway. BY promoted the activity of CAV-1 to influence the activities of receptors and the expressions of downstream protein targets along VEGF signalling pathway. In future, more in-depth investigation are necessary to understand more fully the ultimate clinical outcomes that BY could bring about through its action on HIF-1 and VEGF signaling pathways, besides alleviating neurological severity and minimizing cerebral infarction. Up to this stage of the study, it is confident to claim that Bao Yuan Decoction is a potential drug candidate to deal with cerebral ischemia-reperfusion injury. Based upon systematic review on the research evidence obtained from the respective herbs composing BY, network pharmacology analysis could be a useful platform for predicting mechanistic action of Chinese medicinal formulas, prior to precise investigation by means of animal models. (495 words)