Tanshinone IIA Rescued the Impairments of Primary Hippocampal Neurons Induced by BV2 Microglial Over-Activation

The intervention mechanism of Tanshinone IIA in alleviating neuronal injury induced by HMGB1 or TNF-α-mediated microglial activation

Tanshinone IIA (Tan IIA), a neuroprotective natural compound extracted from Salvia miltiorrhiza, is used in stroke treatment. However, elucidating Tan IIA's neuroprotective mechanisms remains challenging due to limitations in assessing drug efficacy and biochemical parameters in clinical studies. This study investigated Tan IIA's impact on neuroinflammatory responses and its neuroprotective mechanisms using HMGB1- or TNF-α-stimulated BV2 microglia in a co-culture system with primary neuron cells. The results indicated that Tan IIA significantly reduced microglial activation induced by TNF-α or HMGB1. Concurrently, Tan IIA disrupted the interactions between HMGB1 and toll-like receptor 4 (TLR4), and between TNF-α and TNF receptor 1 (TNFR1), modulating the HMGB1/TLR4/nuclear factor-kappa B (NF-κB) and TNF-α/TNFR1/NF-κB signaling pathways and related protein expressions. Moreover, co-culture experiments showed that neuronal apoptosis induced by microglial activation was reversed by Tan IIA. In conclusion, Tan IIA provides neuroprotection by modulating signaling pathways in microglia, thus preventing neuronal apoptosis. This study offers new insights into therapeutic targets for ischemic stroke.

Tanshinone IIA protects motor neuron-like NSC-34 cells against lipopolysaccharide-induced cell injury by the regulation of the lncRNA TCTN2/miR-125a-5p/DUSP1 axis

Background

Tanshinone IIA (TSIIA) exerts a protective role in spinal cord injury (SCI). However, the mechanism of TSIIA activity in SCI remains to be elucidated.

Methods

Cell viability and apoptosis were gauged by CCK-8 assay and flow cytometry, respectively. The expression levels of lncRNA TCTN2, miR-125a-5p and DUSP1 were detected by qRT-PCR and western blot. Direct relationship between miR-125a-5p and TCTN2 or DUSP1 was verified by dual-luciferase reporter assay.

Results

In mouse NSC-34 cells, LPS reduced the expression of TCTN2. TSIIA alleviated cell injury induced by LPS and increased TCTN2 expression in LPS-exposed NSC-34 cells. TCTN2 was a downstream mediator of TSIIA activity. TCTN2 targeted miR-125a-5p, and TCTN2 over-expression attenuated LPS-induced cell damage in NSC-34 cells by down-regulating miR-125a-5p. TCTN2 functioned as a post-transcriptional regulator of DUSP1 expression through miR-125a-5p. DUSP1 was a functional target of miR-125a-5p in controlling NSC-34 cell injury induced by LPS. TSIIA inhibited miR-125a-5p expression and increased the level of DUSP1 protein in LPS-exposed NSC-34 cells.

Conclusion

Our study establishes a novel mechanism, the TCTN2/miR-125a-5p/DUSP1 axis, at least in part, for the protective activity of TSIIA in cell injury induced by LPS.

Effects and mechanisms of tanshinone IIA on PTSD-like symptoms

BACKGROUND

In recent years, Salvia miltiorrhiza and its active substances have remarkably progressed in treating central neurological disorders. Tanshinone IIA (TSA) is an active ingredient derived from the rhizome of Salvia miltiorrhiza that has been found to alleviate the symptoms of several psychiatric illnesses. Post-traumatic stress disorder (PTSD) is a mental disorder that results after experiencing a serious physical or psychological injury. The currently used drugs are not satisfactory for the treatment of PTSD. However, it has been reported that TSA can improve PTSD-like symptoms like learning and memory, cognitive disorder, and depression through multi-target regulation.

PURPOSE

This paper discusses the ameliorative effects of TSA on PTSD-like symptoms and the possible mechanisms of action in terms of inhibition of neuronal apoptosis, anti-neuroinflammation, and anti-oxidative stress. Based on the pathological changes and clinical observations of PTSD, we hope to provide some reference for the clinical transformation of Chinese medicine in treating PTSD.

METHODS

A large number of literatures on tanshinone in the treatment of neurological diseases and PTSD were retrieved from online electronic PubMed and Web of Science databases.

CONCLUSION

TSA is a widely studied natural active ingredient against mental illness. This review will contribute to the future development of TSA as a new clinical candidate drug for improving PTSD-like symptoms.

Pharmacological basis of tanshinone and new insights into tanshinone as a multitarget natural product for multifaceted diseases

Drug development has long included the systematic exploration of various resources. Among these, natural products are one of the most important resources from which novel agents are developed due to the multiple pharmacologic effects of these natural products on diseases. Tanshinone, a representative natural product, is the main compound extracted from the dried root and rhizome of Salvia miltiorrhiza Bge. Research on tanshinone began in the early 1930s. With the in-depth investigation of an increasing number of identified analogs, tanshinone has demonstrated a wide variety of bioactivities and contradicted the saying, 'You can't teach an old dog new tricks'. This review is focused on the pharmacological action of tanshinone and status of research on tanshinone in recent years. The mechanism of tanshinone has also drawn much attention, with the findings of representative targets and pathways of tanshinone. The most recent studies have comprehensively shown that tanshinone can be used to treat leukemia and solid carcinoma, protect against cardiovascular and cerebrovascular diseases, and alleviate liver- and kidney-related diseases, among its other effects. Multiple signaling pathways, including antiproliferative, antiapoptotic, anti-inflammatory, and antioxidative stress pathways, are involved in its actions.

miR-146a alleviates the apoptosis of hippocampal neurons induced by microglia activation via targeting TRAF6

OBJECTIVE

To identify the role of miR-146a and tumor necrosis factor receptor-associated factor 6 (TRAF6) for improving the apoptosis of hippocampal neurons induced by microglia activation.

METHODS

Mouse microglial cell line (BV2 cell) was employed and treated with lipopolysaccharide. Mouse hippocampal nerve cell line (HT22 cell) was then grown in BV2 conditioned medium, and miR-146a overexpression and silencing cell lines were constructed. CCK8 and clone formation test were utilized to evaluate the proliferation ability of the transfected cells, and the level of inflammatory factors was measured by ELISA. Apoptosis was determined extensively by flow cytometry. The apoptosis-related protein and TRAF6 protein expressions were verified by Western blot. TRAF6 was identified to be the target gene of miR-146a based on double Luciferase Report. Finally, both TRAF6 and miR-146a were used to treat HT22 cells and the above indexes were detected repeatedly.

RESULTS

Interleukin (IL)-1β, tumor necrosis factor-α, and IL-6 expressions in BV2 cells increased significantly. miR-146a overexpression distinctly increased the cell proliferation ability and B-cell lymphoma-2 expression ((Bcl-2, p < 0.05); meanwhile, the apoptosis rate of cells, apoptosis-related proteins (Bcl-2 associated X and cleaved caspase-3), and TRAF6 gene and protein expressions were significantly decreased (p < 0.05). However, these above results were reversed for miR-146a silence. There is a targeting relationship between miR-146a and TRAF6. Silencing TRAF6 gene can promote HT22 cells' proliferation and inhibit apoptosis. The effect of miR-146a on HT22 cells was reversed by adding TRAF6 mimics to miR-146a overexpression cells.

CONCLUSION

miR-146a can inhibit the apoptosis of hippocampal neurons caused by microglia activation via targeting TRAF6 and down-regulating its expression.

Tanshinone IIA attenuates demyelination and promotes remyelination in A. cantonensis-infected BALB/c mice

BACKGROUND

Angiostrongylus cantonensis infection can cause demyelination in the central nervous system, and there is no effective treatment.

METHODS

We used dexamethasone, Tanshinone IIA (TSIIA) and Cryptotanshinone(Two traditional Chinese medicine monomers) in combination with albendazole (AB, a standard anti-helminthic compound) to observe their therapeutic effect on demyelination in A. cantonensis-infected mice. Luxol fast blue staining and electron microscope of myelin sheath, Oligodendrocyte (OL) number and myelin basic protein (MBP) expression in brain was detected in above groups.

RESULTS

TSIIA+AB facilitated OL proliferation and significantly increased both myelin sheath thickness and the population of small-diameter axons. In addition, TSIIA treatment inhibited the expression of inflammation-related factors (interleukin [IL]-6, IL-1β, tumor necrosis factor [TNF]-α, inducible nitric oxide synthase [iNOS]) rather than inhibiting eosinophil infiltration in brain. TSIIA also decreased microglial activation and shifted their phenotype from M1 to M2.

CONCLUSIONS

Taken together, these results provide evidence that TSIIA combined with AB may be an effective treatment for demyelination caused by A. cantonensis infection and other demyelinating diseases.

Natural products as a potential modulator of microglial polarization in neurodegenerative diseases

Neurodegenerative diseases (NDs) are characterized by the progressive loss of structure and function of neurons most common in elderly population, mainly including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS). Neuroinflammation caused by microglia as the resident macrophages of the central nervous system (CNS) plays a contributory role in the onset and progression of NDs. Activated microglia, as in macrophages, to be heterogeneous, can polarize into M1 (pro-inflammatory) and M2 (anti-inflammatory) functional phenotypes. The former elaborate pro-inflammatory mediators promoting neuroinflammation and neuronal damage. In contrast, the latter generate anti-inflammatory mediators and neurotrophins that inhibit neuroinflammation and promote neuronal healing. Consistently, the regulation of microglial polarization from M1 to M2 phenotype appears as an outstanding therapeutic and preventive approach for NDs treatment. Although non-steroidal anti-inflammatory drugs (NSAIDs) currently used to alleviate M1 microglia-associated neuroinflammation responsible for the development of NDs, these drugs have different degrees of adverse effects and limited efficacy. As the advantages of novel structure, multi-target, high efficiency and low toxicity, natural products as the modulators of microglial polarization have attracted considerable concerns in the therapeutic areas of NDs. In this review, we mainly summarized the therapeutic potential of natural products and their various molecular mechanisms for NDs treatment through modulating microglial polarization. The aim of the current review is expected to be useful to develop innovative modulators of microglial polarization from natural products for the amelioration and treatment of NDs.

Effects of albendazole combined with TSII-A (a Chinese herb compound) on optic neuritis caused by Angiostrongylus cantonensis in BALB/c mice

Background

Angiostrongylus cantonensis (A. cantonensis) infection can lead to optic neuritis, retinal inflammation, damage to ganglion cells, demyelination of optic nerve and visual impairment. Combined therapy of albendazole and dexamethasone is a common treatment for the disease in the clinic, but it plays no role in vision recovery. Therefore, it has been necessary to explore alternative therapies to treat this disease. Previous studies reported the neuro-productive effects of two constituents of Danshen (a Chinese herb)-tanshinone II-A (TSII-A) and cryptotanshinone (CPT), and this study aims to evaluate the impacts of TSII-A or CPT combined with albendazole on optic neuritis caused by A. cantonensis infection in a murine model.

Methods

To assess the effects of TSII-A or CPT combined with albendazole on optic neuritis due to the infection, mice were divided into six groups, including the normal control group, infection group and four treatment groups (albendazole group, albendazole combined with dexamethasone group, albendazole combined with CPT group and albendazole combined with TSII-A group). The infection group and treatment groups were infected with A. cantonensisand the treatment groups received interventions from 14 dpi (days post infection), respectively. At 21 dpi, the visual acuity of mice in each group was examined by visual evoked potential (VEP). The pathologic alteration of the retina and optic nerve were observed by hematoxylin and eosin (H&E) staining and transmission electronic microscopy (TEM).

Results

Infection of A. cantonensis caused prolonged VEP latency, obvious inflammatory cell infiltration in the retina, damaged retinal ganglions and retinal swelling, followed by optic nerve fibre demyelination and a decreasing number of axons at 21 dpi. In treatment groups, albendazole could not alleviate the above symptoms; albendazole combined with dexamethasone lessened the inflammation of the retina, but was futile for the other changes; however, albendazole combined with CPT and albendazole combined with TSII-A showed obvious effects on the recovery of prolonged VEP latency, destruction and reduction of ganglion cells, optic nerve demyelination and axon loss. Compared with albendazole-CPT compound, albendazole combined with TSII-A was more effective.

Conclusions

The current study demonstrates that albendazole combined with TSII-A plays a more effective role in treating optic neuritis caused by A. cantonensis in mice than with dexamethasone, as applied in conventional treatment, indicating that albendazole combined with TSII-A might be an alternate therapy for this parasitic disease in the clinic.