Schizandrin A ameliorates cognitive functions via modulating microglial polarisation in Alzheimer's disease mice

Gut microbiota and its metabolites in Alzheimer's disease: from pathogenesis to treatment

Introduction

An increasing number of studies have demonstrated that altered microbial diversity and function (such as metabolites), or ecological disorders, regulate bowel-brain axis involvement in the pathophysiologic processes in Alzheimer's disease (AD). The dysregulation of microbes and their metabolites can be a double-edged sword in AD, presenting the possibility of microbiome-based treatment options. This review describes the link between ecological imbalances and AD, the interactions between AD treatment modalities and the microbiota, and the potential of interventions such as prebiotics, probiotics, synbiotics, fecal microbiota transplantation, and dietary interventions as complementary therapeutic strategies targeting AD pathogenesis and progression.

Survey methodology

Articles from PubMed and china.com on intestinal flora and AD were summarized to analyze the data and conclusions carefully to ensure the comprehensiveness, completeness, and accuracy of this review.

Conclusions

Regulating the gut flora ecological balance upregulates neurotrophic factor expression, regulates the microbiota-gut-brain (MGB) axis, and suppresses the inflammatory responses. Based on emerging research, this review explored novel directions for future AD research and clinical interventions, injecting new vitality into microbiota research development.

Schisandrin A enhances pathogens resistance by targeting a conserved p38 MAPK pathway

Schizandrin A (SA), also known as deoxyschizandrin, is one of the most biologically active lignans isolated from the traditional Chinese medicine Fructus schisandrae chinensis. Schisandrin A has proven benefits for anti-cancer, anti-inflammation, hepatoprotection, anti-oxidation, neuroprotection, anti-diabetes. But the influence of Schisandrin A to the innate immune response and its molecular mechanisms remain obscure. In this study, we found that Schisandrin A increased resistance to not only the Gram-negative pathogens Pseudomonas aeruginosa and Salmonella enterica but also the Gram-positive pathogen Listeria monocytogenes. Meanwhile, Schisandrin A protected the animals from the infection by enhancing the tolerance to the pathogens infection rather than by reducing the bacterial burden. Through the screening of the conserved immune pathways in Caenorhabditis elegans, we found that Schisandrin A enhanced innate immunity via p38 MAPK pathway. Furthermore, Schisandrin A increased the expression of antibacterial peptide genes, such as K08D8.5, lys-2, F35E12.5, T24B8.5, and C32H11.12 by activation PMK-1/p38 MAPK. Importantly, Schisandrin A-treated mice also enhanced resistance to P. aeruginosa PA14 infection and significantly increased the levels of active PMK-1. Thus, promoted PMK-1/p38 MAPK-mediated innate immunity by Schisandrin A is conserved from worms to mammals. Our work provides a conserved mechanism by which Schisandrin A enhances innate immune response and boosts its therapeutic application in the treatment of infectious diseases.

Schizandrin A attenuates early brain injury following subarachnoid hemorrhage through suppressing neuroinflammation

BACKGROUND

Early brain injury (EBI) is the vital factor in determining the outcome of subarachnoid hemorrhage (SAH). Schizandrin A (Sch A), the bioactive ingredient extracted from Schisandra chinensis, has been proved to exert beneficial effects in multiple human diseases. However, the effect of Sch A on SAH remains unknown. The current study was designed to explored role and mechanism of Sch A in the pathophysiological process of EBI following SAH.

METHOD

A total of 74 male C57BL/6 J mice were subjected to endovascular perforation to establish the SAH model. Different dosages of Sch A were administrated post-modeling. The post-modeling assessments included neurological test, brain water content, RT-PCR, immunofluorescence, Nissl staining. Oxygenated hemoglobin was introduced into microglia to establish a SAH model in vitro.

RESULT

Sch A significantly alleviated SAH-induced brain edema and neurological impairment. Moreover, application of Sch A remarkably inhibited SAH-induced neuroinflammation, evidenced by the decreased microglial activation and downregulated TNF-α, IL-1β and IL-6 and expression. Additionally, Sch A, both in vivo and in vitro, protected neurons against SAH-induced inflammatory injury. Mechanismly, administration of Sch A inhibited miR-155/NF-κB axis and attenuated neuroinflammation, as well as alleviating neuronal injury.

CONCLUSION

Our data suggested that Sch A could attenuated EBI following SAH via modulating neuroinflammation. The anti-inflammatory effect was exerted, at least partly through the miR-155/NF-κB axis, which may shed light on a possible therapeutic target for SAH.

Schisandrin A regulates the Nrf2 signaling pathway and inhibits NLRP3 inflammasome activation to interfere with pyroptosis in a mouse model of COPD

Chronic obstructive pulmonary disease (COPD) is a serious chronic lung disease. Schisandrin A (SchA) is one of the most important active ingredients in Schisandra chinensis and has been used to treat various lung diseases in several countries. Here, we studied the pharmacological effect of SchA on airway inflammation induced by cigarette smoke (CS) and explored the therapeutic mechanism of SchA in COPD model mice. Our results showed that SchA treatment significantly improved the lung function of CS-induced COPD model mice and reduced the recruitment of leukocytes and hypersecretion of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α) in bronchoalveolar lavage fluid (BALF). H&E staining showed that SchA treatment could effectively reduce emphysema, immune cell infiltration and airway wall destruction. In addition, we found that SchA treatment can stimulate the expression of heme oxygenase-1 (HO-1) through the nuclear factor-erythroid 2-related factor (Nrf2) pathway, significantly reduce oxidative stress, increase catalase (CAT) and superoxide dismutase (SOD) levels, and suppress the level of malondialdehyde (MDA) in COPD model mice. Moreover, SchA treatment suppressed the generation of the NLRP3/ASC/Caspase1 inflammasome complex to inhibit the inflammatory response caused by IL-1β and IL-18 and pyroptosis caused by GSDMD. In conclusion, our study shows that SchA treatment can inhibit the production of ROS and the activation of the NLRP3 inflammasome by upregulating Nrf-2, thereby producing anti-inflammatory effects and reducing lung injury in COPD model mice. More importantly, SchA exhibited similar anti-inflammatory effects to dexamethasone in COPD model mice, and we did not observe substantial side effects of SchA treatment. The high safety of SchA makes it a potential candidate drug for the treatment of COPD.

A comprehensive perspective on the disposition, metabolism, and pharmacokinetics of representative multi-components of Dengzhan Shengmai in rats with chronic cerebral hypoperfusion after oral administration

ETHNOPHARMACOLOGICAL RELEVANCE

Dengzhan Shengmai capsule (DZSM), an evidence-based Chinese medicine comprising Erigeron breviscapus (Vaniot) Hand. -Mazz., Panax ginseng C.A.Mey., Ophiopogon japonicus (Thunb.) Ker Gawl., and Schisandra chinensis (Turcz.) Baill., exhibits an excellent efficacy in treating cardio- and cerebrovascular diseases. It contains caffeoyl compounds, flavonoids, saponins, and lignans as primary active components. However, so far, the characteristics of disposition, metabolism, and pharmacokinetics of its active components remain mostly unclear.

AIM OF STUDY

To elucidate disposition, metabolism, and pharmacokinetics of representative components of DZSM in rats with chronic cerebral hypoperfusion (CCH) by integrating ex vivo and in situ approaches.

MATERIALS AND METHODS

Exposure and distribution of absorbed prototypes and their metabolites were comprehensively investigated using sensitive LC-MS/MS and high-resolution LC-Q-TOF/MS. Pharmacokinetics of representative 16 components (12 prototypes and 4 metabolites) with different chemical categories, relatively high in vivo levels, wide tissue distribution, and reported neuroprotective activities were profiled. The ex vivo everted gut sac and in situ linked-rat models were adopted.

RESULTS

Representative 12 prototypes including 6 caffeoyl compounds (CA, 5-CQA, 3-CQA, 4-CQA, 1,3-CQA, and 3,4-CQA), 1 flavonoid (Scu), 2 saponins (Rd and Rg2), and 3 lignans (SchA, SchB, and SolA) presented characteristic absorption, disposition, and pharmacokinetics profiles in CCH rats. The caffeoyl compounds and flavonoid were well absorbed, exhibited wide distribution, and underwent extensive intestinal metabolism, such as methylation, isomerization, and sulfoconjugation. For CA, 5-CQA, Scu, and 4 related metabolites, the enterohepatic circulation was observed and resulted in bimodal or multimodal pharmacokinetic profiles. Saponins showed relatively low systemic exposure and limited distribution. The PPD-type ginsenoside Rd exhibited longer elimination half-life and systemic circulation than the PPT-type ginsenoside Rg2. No enterohepatic circulation was observed regarding saponins, suggesting that the multimodal pharmacokinetic profile of Rd could be due to its multi-site intestinal absorption. Lignans presented a low in vivo exposure and broad distribution. They were mainly transformed into hydroxylated metabolites. Corresponding to its bimodal pharmacokinetic profile, one metabolite of lignans completed the enterohepatic cycle.

CONCLUSION

The disposition, metabolism, and pharmacokinetic profiles of representative active components of DZSM were comprehensively characterized and elucidated.

Combination of Alpinia Oxyphylla Fructus and Schisandra Chinensis Fructus ameliorates aluminum-induced Alzheimer's disease via reducing BACE1 expression

Being the most common form of dementia, Alzheimer's disease (AD) has a series of modifiable risk factors, including metal ions represented by aluminium. Aluminium (Al) exhibits its neurotoxic effects, especially mainly by affecting amyloid-β protein (Aβ) aggregation and Tau hyperphosphorylation. As reported in our previous study, the combination of Alpinia Oxyphylla Fructus and Schisandra Chinensis Fructus (AS) had a neuroprotective effect. This study aimed to evaluate the anti-AD effect of AS and the mechanism by which AS reduces the neurotoxic effect of Al. Firstly, we used aluminium-maltol (Al(mal)₃) to construct a mouse model of AD and performed oral administration of AS, followed by behavioral experiments, and we collected the mouse brain for immunohistochemistry analysis. In vivo results showed that AS significantly improved Al-induced cognitive decline in mice, and reduced the levels of Aβ_1-42 and P-Tau in the brain, which further proved the anti-AD effect of AS. Then, in order to explore the mechanism by which AS reduced Aβ_1-42, Al-induced PC12 cells were used for the in vitro experiments. Compared with other ratios, the ratio of Alpinia Oxyphylla Fructus: Schisandra Chinensis Fructus (AO:SC) = 1:2 could better improve the cell viability and reduce the Aβ_1-42 level. According to western blot and quantitative real-time polymerase chain reaction (qPCR) results, AS ameliorated the pathological process by downregulating the expression of β-secretase (BACE1), rather than by reducing the expression of amyloid precursor protein (APP) or Tau. These results suggest that AS ameliorated Al-induced AD by affecting the expression of BACE1 and reducing the level of Aβ_1-42, thereby exerting a neuroprotective effect. Combined with previous studies, this study shows that AS has potential for further research and development in AD treatment.

Schisandrin A alleviates mycophenolic acid-induced intestinal toxicity by regulating cell apoptosis and oxidative damage

The gastrointestinal side effects of mycophenolic acid affect its efficacy in kidney transplant patients, which may be due to its toxicity to the intestinal epithelial mechanical barrier, including intestinal epithelial cell apoptosis and destruction of tight junctions. The toxicity mechanism of mycophenolic acid is related to oxidative stress-mediated the activation of mitogen-activated protein kinases (MAPK). Schisandrin A (Sch A), one of the main active components of the Schisandra chinensis, can protects intestinal epithelial cells from deoxynivalenol-induced cytotoxicity and oxidative damage by antioxidant effects. The aim of this study was to investigate the protective effect and potential mechanism of Sch A on mycophenolic acid-induced damage in intestinal epithelial cell. The results showed that Sch A significantly reversed the mycophenolic acid-induced cell viability reduction, restored the expression of tight junction protein ZO-1, occludin and reduced cell apoptosis. In addition, Sch A inhibited mycophenolic acid-mediated MAPK activation and reactive oxygen species (ROS) increase. Collectively, our study showed that Sch A protected intestinal epithelial cells from mycophenolic acid intestinal toxicity, at least in part, by reducing oxidative stress and inhibiting MAPK signaling pathway.