The neuroprotective effect of phillyrin in intracerebral hemorrhagic mice is produced by activation of the Nrf2 signaling pathway

Phillyrin ameliorates DSS-induced colitis in mice via modulating the gut microbiota and inhibiting the NF-κB/MLCK pathway

Phillyrin (PHY), also known as forsythin, is an active constituent isolated from the fruit of Forsythia suspensa (Thunb.) Vahl (Oleaceae). It exhibits anti-inflammatory, anti-viral, and antioxidant properties. However, the precise impact of PHY on colitis induced by dextran sodium sulfate (DSS) and its mechanism remain elusive. The present investigation revealed that PHY (12.5, 25.0, and 50.0 mg/kg) exhibited significant therapeutic efficacy in protecting mice against DSS-induced colitis. This effect was manifested as reduced weight loss, a shortened colon, increased secretion of inflammatory factors, increased intestinal permeability, and an enhanced disease activity index in mice with ulcerative colitis (UC). Molecular investigations have determined that PHY mitigates the nuclear translocation of nuclear factor kappa B, thereby downregulating myosin light-chain kinase-driven myosin light-chain phosphorylation. This mechanism results in the preservation of the integrity of the intestinal barrier. The outcomes of 16S rRNA sequencing suggest that PHY (50 mg/kg) augmented the relative abundance of certain probiotic strains, including Lactobacillaceae and Lachnospiraceae. Additionally, PHY supplementation elevated the short-chain fatty acid contents within the intestinal contents of mice with UC. In conclusion, pre-treatment with PHY may ameliorate the DSS-induced UC in mice by lowering the expression of inflammatory factors, protecting intestinal barrier function, and enhancing the structure of the intestinal flora.IMPORTANCEThe protective effect of phillyrin on DSS-induced colitis was explained for the first time, and the anti-inflammatory effect of phillyrin was demonstrated by fecal microbiota transplantation experiments mainly through intestinal flora.

Phillyrin promotes autophagosome formation in A53T-αSyn-induced Parkinson's disease model via modulation of REEP1

BACKGROUND

The preservation of autophagosome formation presents a promising strategy for tackling neurological disorders, such as Parkinson's disease (PD). Mitochondria-associated endoplasmic reticulum (ER) membranes (MAM) serve not only as a focal point linked to various neurological disorders but also play a crucial role in supporting the biogenesis of autophagosomes.

PURPOSE

This investigation aimed to elucidate the neuroprotective properties of phillyrin against PD and its underlying mechanisms in promoting autophagosome formation.

METHODS

ER and mitochondria co-localization was assessed via fluorescent staining. Annexin V-fluorescein isothiocyanate (FITC) fluorescence was employed to quantify accessible cardiolipin (CL) on mitochondrial surfaces. The levels of CL within the MAM fraction of SH-SY5Y cells were evaluated using a CL probe assay kit. Monodansylcadaverine staining was utilized to detect autophagosome formation in SH-SY5Y cells. In an A53T-alpha-synuclein (αSyn)-induced PD mouse model, the anti-PD properties of phillyrin were assessed using open field, pole climbing, and rotarod tests, as well as immunohistochemistry staining of TH+ neurons in the brain sections.

RESULTS

In A53T-αSyn-treated SH-SY5Y cells, phillyrin facilitated autophagosome formation by suppressing CL externalization and restoring MAM integrity. Phillyrin enhanced the localization of receptor expression-enhancing protein 1 (REEP1) within MAM and mitochondria, bolstering MAM formation. Increased REEP1 levels in mitochondria, attributed to phillyrin, enhanced the interaction between REEP1 and NDPK-D, thereby reducing CL externalization. Furthermore, phillyrin exhibited a dose-dependent enhancement of motor function in mice, accompanied by an increase in the abundance of dopaminergic neurons within the substantia nigra.

CONCLUSIONS

These findings illuminate phillyrin's ability to enhance MAM formation through upregulation of REEP1 expression within MAM, while concurrently attenuating CL externalization via the REEP1-NDPK-D interaction. These mechanisms bolster autophagosome biogenesis, offering resilience against A53T-αSyn-induced PD. Thus, our study advances the understanding of phillyrin's complex mechanisms and underscores its potential as a therapeutic approach for PD, opening new avenues in natural product pharmacology.

Selenomethionine alleviates Aeromonas hydrophila-induced oxidative stress and ferroptosis via the Nrf2/HO1/GPX4 pathway in grass carp

Aeromonas hydrophila infection is a severe, acute, and life-threatening disease affecting grass carp (Ctenopharyngodon idella) in aquaculture. Ferroptosis is a novel form of cell death characterized by the accumulation of free iron and harmful lipid peroxides within cells. While selenomethionine (Se-Met) is known to effectively inhibit ferroptosis and alleviate cell damage, its ability to counteract oxidative stress and ferroptosis induced by A. hydrophila remains unclear. The objective of this study is to reveal the possible mechanism behind the ferroptosis phenomenon during A. hydrophila infection. We established a macrophage model of A. hydrophila invasion to monitor the dynamic changes in iron metabolism markers to evaluate the correlation between ferroptotic stress and A. hydrophila infection. A. hydrophila infection induces cytotoxicity and mitochondrial membrane damage via ferroptosis. This damage is attributed to the accumulation of lipid peroxides due to intracellular ferrous ion overload and glutathione depletion. Supplementation of Se-Met reduced mitochondrial damage, enhanced antioxidant enzyme activity and reduced ferroptosis by activating the Nrf2/HO1/GPX4 axis. These findings provide new insights into the regulatory mechanisms of A. hydrophila-induced ferroptosis in teleosts and suggest that targeted inhibition of ferroptosis may offer a novel therapeutic strategy for managing A. hydrophila infections.

Review of the therapeutic potential of Forsythiae Fructus on the central nervous system: Active ingredients and mechanisms of action

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine has gained significant attention in recent years owing to its multi-component, multi-target, and multi-pathway advantages in treating various diseases. Forsythiae Fructus, derived from the dried fruit of Forsythia suspensa (Thunb.) Vahl, is one such traditional Chinese medicine with numerous in vivo and ex vivo therapeutic effects, including anti-inflammatory, antibacterial, and antiviral properties. Forsythiae Fructus contains more than 200 chemical constituents, with forsythiaside, forsythiaside A, forsythiaside B, isoforsythiaside, forsythin, and phillyrin being the most active ingredients. Forsythiae Fructus exerts neuroprotective effects by modulating various pathways, including oxidative stress, anti-inflammation, NF-κB signaling, 2-AG, Nrf2 signaling, acetylcholinesterase, PI3K-Akt signaling, ferroptosis, gut-brain axis, TLR4 signaling, endoplasmic reticulum stress, PI3K/Akt/mTOR signaling, and PPARγ signaling pathway.

AIM OF THE STUDY

This review aims to highlight the potential therapeutic effects of Forsythiae Fructus on the central nervous system and summarize the current knowledge on the active ingredients of Forsythiae Fructus and their effects on different pathways involved in neuroprotection.

MATERIALS AND METHODS

In this review, we conducted a comprehensive search of databases (PubMed, Google Scholar, Web of Science, China Knowledge Resource Integrated, local dissertations and books) up until June 2023 using key terms such as Forsythia suspensa, Forsythiae Fructus, forsythiaside, isoforsythiaside, forsythin, phillyrin, Alzheimer's disease, Parkinson's disease, ischemic stroke, intracerebral hemorrhage, traumatic brain injury, aging, and herpes simplex virus encephalitis.

RESULTS

Our findings indicate that Forsythiae Fructus and its active ingredients own therapeutic effects on the central nervous system by modulating various pathways, including oxidative stress, anti-inflammation, NF-κB signaling, 2-AG, Nrf2 signaling, acetylcholinesterase, PI3K-Akt signaling, ferroptosis, the gut-brain axis, TLR4 signaling, endoplasmic reticulum stress, PI3K/Akt/mTOR signaling, and PPARγ signaling pathway.

CONCLUSION

Forsythiae Fructus and its active ingredients have demonstrated promising neuroprotective properties. Future in vivo and clinical studies of Forsythiae Fructus and its active ingredients should be conducted to establish precise dosage and standard guidelines for a more effective application in the treatment of neurological disorders.

Natural products and their derivatives alleviating cerebral white matter lesions

White matter lesions (WMLs), characterized by focal demyelination or myelination disorders, are commonly present in cerebral small vessel disease and various neurological diseases. Multiple etiologies lead to WMLs. However, there is no specific therapy or effective drugs for relieving WMLs. Natural products and their derivatives originate from bacterial, fungal, plant, and marine animal sources, many of which have multiple therapeutic targets. Compared to single target compounds, natural products and their derivatives are promising to be developed as better drugs to attenuate WMLs. Thus, this review attempts to summarize the status of natural products and their derivatives (2010-to date) alleviating cerebral white matter lesions for the discovery of new drugs.

Unraveling the protective role of Nrf2 in molluscs: Insights into mitochondrial and apoptosis pathways in the defense against Bap-induced oxidative stress

Benzopyrene (Bap) is a major constituent of petroleum pollutants commonly found in aquatic environments, and its mutagenic and carcinogenic properties have adverse effects on aquatic organisms' development, growth, and reproduction. The antioxidant defense system element, NF-E2-related factor 2 (Nrf2), has been linked to the oxidative stress response in marine invertebrates exposed to toxic substances. In a previous study, a novel Nrf2 homologue, McNrf2, was identified in mussel Mytilus coruscus, a significant model marine molluscs in ecotoxicology studies. McNrf2 showed the potential to trigger an antioxidant defense against oxidative stress induced by Bap. Here, we employed an Nrf2 overexpression and inhibition model using SFN and ML385 as Nrf2 inducer and inhibitor, respectively. Next, immunofluorescence technique was used to evaluate the nuclear activation of Nrf2 induced by Bap-mediated oxidative stress. Transmission electron microscopy revealed that overexpression of Nrf2 could maintain the quantity and structural integrity of mitochondria, while flow cytometry analysis showed that Nrf2 could alleviate Bap-induced cellular apoptosis. These findings suggest that Nrf2 can protect molluscs from Bap-induced oxidative stress through the mitochondria and apoptosis pathways, providing a novel perspective on Nrf2's antioxidant function.

Regulation of nuclear factor erythroid-2-related factor 2 as a potential therapeutic target in intracerebral hemorrhage

Hemorrhagic stroke can be categorized into several subtypes. The most common is intracerebral hemorrhage (ICH), which exhibits significant morbidity and mortality, affecting the lives of millions of people worldwide every year. Brain injury after ICH includes the primary injury that results from direct compression as well as stimulation by the hematoma and secondary brain injury (SBI) that is due to ischemia and hypoxia in the penumbra around the hematoma. A number of recent studies have analyzed the mechanisms producing the oxidative stress and inflammation that develop following hematoma formation and are associated with the ICH induced by the SBI as well as the resulting neurological dysfunction. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a critical component in mediating oxidative stress and anti-inflammatory response. We summarize the pathological mechanisms of ICH focusing on oxidative stress and the regulatory role of Nrf2, and review the mechanisms regulating Nrf2 at the transcriptional and post-transcriptional levels by influencing gene expression levels, protein stability, subcellular localization, and synergistic effects with other transcription factors. We further reviewing the efficacy of several Nrf2 activators in the treatment of ICH in experimental ICH models. Activation of Nrf2 might produce antioxidant, anti-inflammatory, and neuron-protection effects, which could potentially be a focus for developing future treatments and prevention of ICH.

Targeting Oxidative Stress in Intracerebral Hemorrhage: Prospects of the Natural Products Approach

Intracerebral hemorrhage (ICH), the second most common subtype of stroke, remains a significant cause of morbidity and mortality worldwide. The pathological mechanism of ICH is very complex, and it has been demonstrated that oxidative stress (OS) plays an important role in the pathogenesis of ICH. Previous studies have shown that OS is a therapeutic target after ICH, and antioxidants have also achieved some benefits in the treatment of ICH. This review aimed to explore the promise of natural products therapy to target OS in ICH. We searched PubMed using the keywords "oxidative stress in intracerebral hemorrhage" and "natural products in intracerebral hemorrhage". Numerous animal and cell studies on ICH have demonstrated the potent antioxidant properties of natural products, including polyphenols and phenolic compounds, terpenoids, alkaloids, etc. In summary, natural products such as antioxidants offer the possibility of treatment of OS after ICH. However, researchers still have a long way to go to apply these natural products for the treatment of ICH more widely in the clinic.

Targeting Oxidative Stress and Inflammatory Response for Blood-Brain Barrier Protection in Intracerebral Hemorrhage

Significance: Blood-brain barrier (BBB) disruption is a major pathological change after intracerebral hemorrhage (ICH) and is both the cause and result of oxidative stress and of the immune response post-ICH. These processes contribute to ICH-induced brain injury. Recent Advances: After the breakdown of cerebral vessels, blood components, including erythrocytes and their metabolites, thrombin, and fibrinogen, can access the cerebral parenchyma through the compromised BBB, triggering oxidative stress and inflammatory cascades. These aggravate BBB disruption and contribute to further infiltration of blood components, resulting in a vicious cycle that exacerbates brain edema and neurological injury after ICH. Experimental and clinical studies have highlighted the role of BBB disruption in ICH-induced brain injury. Critical Issues: In this review, we focus on the strategies to protect the BBB in ICH. Specifically, we summarize the evidence and the underlying mechanisms, including the ICH-induced process of oxidative stress and inflammatory response, and we highlight the potential therapeutic targets to protect BBB integrity after ICH. Future Directions: Future studies should probe the mechanism of ferroptosis as well as oxidative stress-inflammation coupling in BBB disruption after ICH and investigate the effects of antioxidants and immunomodulatory agents in more ICH clinical trials. Antioxid. Redox Signal. 37, 115-134.

Tanhuo Formula Inhibits Astrocyte Activation and Apoptosis in Acute Ischemic Stroke

Tanhuo formula (THF), a traditional Chinese medicinal formula, has been demonstrated to be effective in the clinical treatment of acute ischemic stroke (AIS). However, its active ingredients, potential targets, and molecular mechanisms remain unknown. Based on the validation of active ingredient concentrations, our study attempted to elucidate the possible mechanisms of THF based on network pharmacological analysis and experimental validation. Components of THF were screened using network pharmacological analysis, and a compound–target network and protein–protein interaction (PPI) network were constructed. In total, 42 bioactive compounds and 159 THF targets related to AIS were identified. The PPI network identified AKT1, TNF, IL6, IL1B, and CASP3 as key targets. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis demonstrated that the inflammation and apoptotic pathways were enriched by multiple targets. The main components of THF were identified via high-performance liquid chromatography. Subsequently, a validation experiment was conducted, and the expressions of GFAP, C3, TNF-α, and IL-6 were detected via immunofluorescence staining, confirming the inflammatory response at 30 min and 3 days post injury. Immunohistochemical staining for caspase-3 and TUNEL was also performed to assess apoptosis at the same time points. These results indicate that THF can effectively decrease neural cell apoptosis through the caspase-3 pathway and restrain excessive abnormal activation of astrocytes and the release of TNF-α and IL-6, which might be accompanied by the recovery of motor function. Thus, THF may serve as a promising therapeutic strategy for AIS through multiple targets, components, and pathways.

Heme Oxygenase-1 may Mediate Early Inflammatory Response of Intracerebral Hemorrhage through Toll-like Receptor 4 Signaling Pathway

OBJECTIVE

The aim of this study was to investigate whether heme oxygenase-1 (HO-1) promotes an early neuroinflammatory response after intracerebral hemorrhage (ICH) by regulating the toll-like receptor 4 (TLR4) signaling pathway.

METHODS

We used a stereotaxic instrument to induce a mouse model of ICH through collagenase. We divided the participants into a control group, an ICH group, and an ICH and zinc protoporphyrin IX (ZnPP) group. The temporal expression pattern and cell localization of HO-1 and TLR4 after the ICH were detected by immunofluorescence and western blot; after the expression of HO-1 was inhibited, the expression levels of the TLR4 protein, the downstream molecule myeloid differentiation factor 88 (MyD88), the Toll and interleukin-1 receptor (TIR) -domain-containing adapter-inducing interferon-β (TRIF) and the inflammatory factors were measured by western blotting.

RESULTS

Immunofluorescence showed that HO-1 and TLR4 had similar temporal expression patterns and cellular localization after ICH, and we found that inhibiting HO-1 reduces the expression of TLR4 protein pathways, including TLR4, MyD88, TRIF, and related inflammatory factors, by studying the inhibitor ZnPP.

CONCLUSION

These results indicate that HO-1 may promote early neuroinflammation after ICH through the TLR4/MyD88/TRIF signaling pathway.

Phillyrin Prevents Neuroinflammation-Induced Blood-Brain Barrier Damage Following Traumatic Brain Injury via Altering Microglial Polarization

Background: Phillyrin (Phi) is the main polyphenolic compound found in Forsythia suspensa. Recent studies have revealed that Phi has potent antioxidative and anti-inflammatory effects. However, whether Phi could relieve blood-brain barrier (BBB) damage following traumatic brain injury (TBI) remains unknown. Materials and Methods: Lipopolysaccharide (LPS) was used to activate primary microglia, which were then treated with different doses of Phi or the peroxisome proliferator-activated receptor-gamma (PPARγ) antagonist (GW9662). CCK-8 assay was used for evaluating cell viability, and the cytokines (including IL-1β, IL-6, TNFα, IL-4, IL-10, and TGFβ), microglial phenotypic markers (iNOS, COX2, and CD86 for "M1" polarization; Arg1, Ym1, and CD206 for "M2" polarization), PPARγ, and NF-κB were determined by RT-PCR, Western blot, or cellular immunofluorescence. Primary cultured mouse brain microvascular endothelial cells (BMECs) were stimulated by the condition medium (CM) from microglia. The cell viability, angiogenesis, and tight junction of BMECs were determined via CCK-8 assay, tube formation assay, and Western blot (for detecting MMP3, MMP9, ZO1, claudin-5, and occludin). Furthermore, the mouse TBI model was constructed and treated with Phi and/or GW9662. The BBB integrity was evaluated by H&E staining, Evans blue staining, and tissue immunofluorescence. Results: Phi markedly restrained the pro-inflammatory ("M1" state) cytokines and promoted anti-inflammatory ("M2" polarization) cytokines in LPS-mediated microglia. Phi mitigated "M1" polarization and promoted "M2" polarization of microglia via enhancing PPARγ and inhibiting the NF-κB pathway. The PPARγ antagonist GW9662 significantly repressed Phi-mediated anti-inflammatory effects. Meanwhile, Phi enhanced the viability, tube formation ability, and cell junction of BMECs. In the TBI mouse model, Phi promoted "M2" polarization, whereas it repressed the "M1" polarization of microglia. In addition, Phi reduced TBI-mediated BBB damage. However, the protective effects of Phi were reversed mainly by GW9662 treatment. Conclusion: Phi prevents BBB damage via inhibiting the neuroinflammation of microglia through the PPARγ/NF-κB pathway, which provides a potential therapeutic drug against TBI.