Rhein Suppresses Neuroinflammation via Multiple Signaling Pathways in LPS-Stimulated BV2 Microglia Cells

Rhein alleviates MPTP-induced Parkinson's disease by suppressing neuroinflammation via MAPK/IκB pathway

Background

Parkinson's disease (PD) is a common neurodegenerative disease with a rapid increase in incidence in recent years. Existing treatments cannot slow or stop the progression of PD. It was proposed that neuroinflammation leads to neuronal death, making targeting neuroinflammation a promising therapeutic strategy. Our previous studies have demonstrated that rhein protects neurons in vitro by inhibiting neuroinflammation, and it has been found to exhibit neuroprotective effects in Alzheimer's disease and epilepsy, but its neuroprotective mechanisms and effects on PD are still unclear.

Methods

PD animal model was induced by 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP). ELISA, RT-qPCR, western blot and Immunofluorescence were used to detect the levels of inflammatory cytokines and M1 polarization markers. The protein expression levels of signaling pathways were measured by western blot. Hematoxylin-eosin (HE) staining showed that rhein did not damage the liver and kidney. Two behavioral tests, pole test and rotarod test, were used to evaluate the improvement effect of rhein on movement disorders. The number of neurons in the substantia nigra was evaluated by Nissl staining. Immunohistochemistry and western blot were used to detect tyrosine hydroxylase (TH) and α-synuclein.

Results

Rhein inhibited the activation of MAPK/IκB signaling pathway and reduced the levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and M1 polarization markers of microglia in vivo. In a mouse model of PD, rhein ameliorated movement disorders, reduced dopaminergic neuron damage and α-synuclein deposition.

Conclusion

Rhein inhibits neuroinflammation through MAPK/IκB signaling pathway, thereby reducing neurodegeneration, α-synuclein deposition, and improving movement disorders in Parkinson's disease.

Rhein inhibits M1 polarization of BV2 microglia through MAPK/IκB signalling pathway and reduces neurotoxicity caused by neuroinflammation

BACKGROUND

Rhein is an anthraquinone compound with anti-inflammatory pharmacological activity. It has been found to play a neuroprotective role in neurological diseases, but the neuroprotective mechanism of rhein remains unclear.

METHODS

SH-SY5Y cells serving as neuron-like cells and BV2 microglia were used. The toxicity of rhein on BV2 microglia and the viability of SH-SY5Y cells were measured by CCK-8 assay. The mRNA expression and secretion of pro-inflammatory cytokines were detected by qPCR and ELISA. Iba1, CD86 and pathway signalling protein in BV2 microglia were assessed by Western blot and immunofluorescence. Apoptosis of SH-SY5Y cells exposed to neuroinflammation was analysed through flow cytometry.

RESULTS

Rhein inhibited MAPK/IκB signalling pathways. Further studies revealed that rhein inhibited the production of pro-inflammatory cytokines TNF-α, IL-6, IL-1β and iNOS in BV2 cells and also inhibited the expression of M1 polarization markers Iba1 and CD86 in BV2 cells. Furthermore, rhein reduced the apoptotic rate and restored cell viability of SH-SY5Y cells exposed to neuroinflammation.

CONCLUSIONS

Our study demonstrated that rhein inhibited microglia M1 polarization via MAPK/IκB signalling pathway and protected nerve cells through suppressing neuroinflammation.

Notoginsenoside R1 restrains the proliferation and migration of airway smooth muscle cells isolated from rats with chronic obstructive pulmonary disease

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a common disorder that is characterized by systemic and lung inflammation. Notoginsenoside R1 (NGR1) displays anti-inflammatory properties in numerous diseases. We aimed to explore the function and mechanism of NGR1 in COPD.

MATERIALS AND METHODS

COPD rats were established through cigarette smoke exposure, lipopolysaccharide injection, and cold stimulation. Rat airway smooth muscle cells (ASMCs) were separated and identified. Then, ASMCs were treated with NGR1 (25 or 50 μM) and cigarette smoke extract (CSE). Thereafter, the vitality, proliferation, and migration of ASMCs were measured. Additionally, cell cycle, inflammation-related factors, α-SMA, and PI3K/AKT pathway-related marker expressions of the ASMCs were also detected. Molecular docking experiments were conducted to explore the interaction of NGR1 to PI3K, TGF-β, p65, and AKT. Moreover, 740 Y-P (a PI3K/Akt pathway agonist) were used to validate the mechanism of NGR1 on COPD.

RESULTS

NGR1 inhibited the proliferation and migration, but caused cell cycle arrest for CSE-triggered ASMCs. Furthermore, NGR1 not only decreased IL-1β, IL-6, IL-8, and TNF-α contents, but also reduced α-SMA expression in CSE-stimulated ASMCs. Moreover, NGR1restrainedTGF-β1 expression, PI3K, p65, and AKT phosphorylation in CSE-stimulated ASMCs. Molecular docking experiments showed NGR1 exhibited a strong binding ability to PI3K, TGF-β1, p65, and AKT. Notably, the effects of NGR1 on the proliferation and migration of CSE-induced ASMCs were reversed by 740 Y-P.

CONCLUSIONS

NGR1 can restrain the proliferation and migration of CSE-induced ASMCs, indicating that NGR1 may be a therapeutic candidate for treating COPD.

RNA m6A methylation regulators in sepsis

N6-methyladenosine (m6A) modification is a class of epitope modifications that has received significant attention in recent years, particularly in relation to its role in various diseases, including sepsis. Epigenetic research has increasingly focused on m6A modifications, which is influenced by the dynamic regulation of three protein types: ‟Writers" (such as METTL3/METTL14/WTAP)-responsible for m6A modification; ‟Erasers" (FTO and ALKBH5)-involved in m6A de-modification; and ‟Readers" (YTHDC1/2, YTHDF1/2/3)-responsible for m6A recognition. Sepsis, a severe and fatal infectious disease, has garnered attention regarding the crucial effect of m6A modifications on its development. In this review, we attempted to summarize the recent studies on the involvement of m6A and its regulators in sepsis, as well as the significance of m6A modifications and their regulators in the development of novel drugs and clinical treatment. The potential value of m6A modifications and modulators in the diagnosis, treatment, and prognosis of sepsis has also been discussed.

Quassinoids from Picrasma chinensis with Insecticidal Activity against Adults and Larvae of Diaphorina citri Kuwayama and Neuroprotective Effect

Eleven new tetracyclic quassinoids, picrachinensin A-K (1-11), along with six known congeners, were isolated from the stems and leaves of Picrasma chinensis. Their structures were elucidated by integrated multiple spectroscopic techniques, single-crystal X-ray diffraction analysis, and electronic circular dichroism. Notably, compounds 3 and 4 are a pair of undescribed epimers, and 8 and 9 are unusual quassinoids with a hydroxymethyl group at C-13. Biologically, compound 7 exhibited insecticidal activity on both adults and larvae of Diaphorina citri Kuwayama even more effectively than the positive control (abamectin), with an LD₅₀ of 55.69 mg/L for adults and a corrected mortality rate of 30.42 ± 2.78% for larvae (100 mg/L). According to preliminary structure-activity relationship investigations, the hydroxymethyl at the C-13 position of quassinoids was beneficial for their insecticidal activity. In addition, compounds 1, 4, and 12 exhibited excellent neuroprotective effect against H₂O₂-induced oxidative injury on SH-SY5Y cells, with more potent activity than the positive control (Trolox), and all the compounds exhibited no cytotoxicity to SH-SY5Y and BV-2 cells at the indicated concentrations.

Meloxicam Inhibited the Proliferation of LPS-Stimulated Bovine Endometrial Epithelial Cells Through Wnt/β-Catenin and PI3K/AKT Pathways

Meloxicam is a non-steroidal anti-inflammatory drug and has been used to relieve pain and control inflammation in cows with metritis and endometritis. Meloxicam has been found to be effective in inhibiting tissue or cell growth when it is used as an anti-inflammatory therapy. However, the influence of meloxicam on bovine endometrial regeneration has not been reported. This study was to research the effect of meloxicam (0.5 and 5 μM) on the proliferation of primary bovine endometrial epithelial cells (BEECs) stimulated by Escherichia coli lipopolysaccharide. The cell viability, cell cycle, and cell proliferation were evaluated by Cell Counting Kit-8, flow cytometry, and cell scratch test, respectively. The mRNA transcriptions of prostaglandin-endoperoxide synthase 1 (PTGS1) and PTGS2, Toll-like receptor 4, and proliferation factors were detected using quantitative reverse-transcription polymerase chain reaction. The activations of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and Wnt/β-catenin pathways were determined using western blot and immunofluorescence. As a result, co-treatment of meloxicam and lipopolysaccharide inhibited (P < 0.05) the cell cycle progression and reduced (P < 0.05) the cell healing rate and the mRNA level of proliferation factors as compared with the cells treated with lipopolysaccharide alone. Meloxicam decreased (P < 0.05) the lipopolysaccharide-induced PTGS2 gene expression. Neither lipopolysaccharide nor meloxicam changed PTGS1 mRNA abundance (P > 0.05). Meloxicam inhibited (P < 0.05) the lipopolysaccharide-activated Wnt/β-catenin pathway by reducing (P < 0.05) the protein levels of β-catenin, c-Myc, cyclin D1, and glycogen synthase kinase-3β and prevented the lipopolysaccharide-induced β-catenin from entering the nucleus. Meloxicam suppressed (P < 0.05) the phosphorylation of PI3K and AKT. In conclusion, meloxicam alone did not influence the cell cycle progression or the cell proliferation in BEEC but caused cell cycle arrest and inhibited cell proliferation in lipopolysaccharide-stimulated BEEC. This inhibitory effect of meloxicam was probably mediated by Wnt/β-catenin and PI3K/AKT pathways.

Rhein attenuates PTZ‑induced epilepsy and exerts neuroprotective activity via inhibition of the TLR4-NFκB signaling pathway

BACKGROUND

Epilepsy is a common neurological disease that cannot be well controlled by existing antiepileptic drugs. Studies have implicated oxidative stress and inflammation in the pathophysiology of epilepsy. Rhein has a comprehensive pharmacological function in reducing inflammation and can play a neuroprotective role in many neurological diseases, however little is known about its effects on epilepsy.

METHODS

A model of acute epilepsy in mice was established using the Pentylenetetrazol (PTZ) ignition method to evaluate the effects of Rhein on the duration and latency of convulsions, and the number and severity of seizures. Modified Neurological Severity Score (mNSS), Rotarod and open-field behavioral task tests were performed to evaluate the neuroprotective effect of Rhein. TUNEL staining was used to assess neuronal damage, and western blot, qPCR and ELISA kits were utilized to determine the expression of inflammatory signaling protein molecules and levels of inflammatory cytokines.

RESULTS

In this study, we demonstrate that Rhein delayed the onset of seizures, decreased their severity, and reduced the duration and frequency of seizures in PTZ-induced epileptic mice. Furthermore, we found that Rhein blocked neurological deficits induced by PTZ. In addition, our results show that Rhein inhibited the activation of the TLR4-NFκB signaling pathway and decreased the secretion of the inflammatory cytokines TNF-α, IL-6, IL-1β, and IL-18.

CONCLUSION

Our results suggest that the anticonvulsant and neuroprotective effects of Rhein are achieved by disrupting the processes involved in PTZ acquisition of epilepsy.

Polydatin inhibits LPS-induced inflammatory response in BV2 microglia by disrupting the formation of lipid rafts

OBJECTIVE

Polydatin has been used in the treatment of various inflammatory diseases. However, its role in the regulation of neuroinflammation has not been reported. In this study, we designed to investigate the anti-inflammatory effects of polydatin in LPS-stimulated BV2 microglia cells.

METHODS

Inflammatory mediators TNF-α, IL-1β, NO, and PGE2 production were measured by ELISA. The protein of signaling pathways were detected by western blot analysis.

RESULTS

The results showed that polydatin significantly ameliorated the production of TNF-α, IL-1β, NO, and PGE2 up-regulated by LPS. Polydatin also blocked LPS-induced NF-κB activation. In addition, PI3K and AKT, the up-stream molecules of NF-κB signaling pathway, were inhibited by the treatment of polydatin. Also, we found the formation of lipid rafts was inhibited by polydatin through attenuating the cholesterol content. Finally, polydatin was found to increase the expression of ABCA1 and ABCG1.

CONCLUSION

In conclusion, the results of the present study suggested that polydatin exhibited its anti-inflammatory effects in BV2 cells through disrupting lipid rafts, which subsequently inhibiting PI3K/AKT signaling pathway.