Peucedani Japonici Radix ameliorates lipopolysaccharide-induced neuroinflammation by regulating microglial responses

Active ingredients of Chinese medicine with immunomodulatory properties: NF-κB pathway and Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease with a complex pathogenesis and no cure. Persistent neuroinflammation plays an important role in the development of PD, and activation of microglia and astrocytes within the central nervous system leads to an inflammatory response and production of pro-inflammatory factors, and activation of NF-κB is key to neuroglial activation in chronic inflammation in PD and a hallmark of the onset of neuroinflammatory disease. Therefore, inhibiting NF-κB activation to prevent further loss of dopaminergic nerves is a more effective means of treating PD. It has been found that an increasing number of active ingredients in Chinese medicines, such as flavonoids, alkaloids, saponins, terpenoids, phenols and phenylpropanoids, have anti-inflammatory properties that can regulate neuroglia cell activation and ameliorate neuroinflammation through the NF-κB pathway, and increase dopamine release or protect dopaminergic neurons for neuroprotection to improve behavioural dysfunction in PD. The active ingredients of traditional Chinese medicine are expected to be good candidates for the treatment of PD, as they provide holistic regulation through multi-targeting and multi-level effects, and are safe, inexpensive and readily available. Therefore, this paper summarises that the active ingredients of some relevant Chinese medicines ameliorate the symptoms of PD and delay the development of PD by inhibiting glial cell-mediated neuroinflammation through the NF-κB pathway, which may provide new ideas for exploring the molecular mechanism of PD pathogenesis and developing new anti-PD drugs.

Praeruptorin A inhibits the activation of NF-κB pathway and the expressions of inflammatory factors in poly (I:C)-induced RAW264.7 cells

Praeruptorin A (PA), a natural coumarin compound, has significant anti-inflammatory effects. In this study, we evaluate the anti-inflammatory effect of PA on RAW 264.7 mouse macrophages induced by Polyinosinic acid-polycytidylic acid (poly (I:C)). RAW 264.7 mouse macrophages induced by poly (I:C) were treated with or without PA, the viability of which was determined to screen working solution of PA. RNA-sequencing was applied to analyze the differentially expressed genes (DEGs). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were carried out. The expressions of interleukin (IL)-1β, heme oxygenase 1 (HMOX1), prostaglandin-endoperoxide synthase 2 (PTGS2), ATP binding cassette subfamily A member 1 (Abca1) and NF-κB-related proteins were measured by enzyme-linked immunosorbent assay (ELISA), quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot. As a result, PA at 1, 2, 3, 4 and 5 μM slightly affected cell viability, while PA at 6 and 7 μM significantly inhibited cell viability. GO and KEGG analysis results revealed that DEGs were mainly enriched in the pathways related to inflammatory signaling. Through further analysis, we obtained five possible targets of PA, and verified that PA inhibited the expressions of IL-1β, HMOX1, PTGS2 and Abca1 as well as the activation of NF-κB pathway in poly (I:C)-induced RAW264.7 cells. To summarize, PA may inhibit expressions of the inflammation-related genes in poly (I:C)-induced RAW264.7 cells, which demonstrates its potential as a drug against virus related diseases.

Protective effects of CCL01 against Aβ-induced neurotoxicity in 5xFAD transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is the most common dementia characterized by the excessive accumulation of amyloid-beta (Aβ) and tau aggregates, as well as neuronal damage and neuroinflammation. Metabolic disruption in AD has been noticed because metabolite alterations closely correlate with Aβ neuropathology and behavioral phenotypes. Accordingly, controlling various neuropathological processes and metabolic disruption is an efficient therapeutic strategy for AD treatment. In this study, we evaluated the effects of a combination of Cuscuta seeds and Lactobacillus paracasei NK112 (CCL01) on AD neuropathology and altered metabolism in five familial AD (5xFAD) transgenic mice and neuronal cell cultures. First, we observed that CCL01 exerted neuroprotective effects in HT22 hippocampal neurons and primary cultured neurons. CCL01 ameliorated memory decline and protected synapses and neuronal survival in 5xFAD mice. These effects were related to the inhibition of tau phosphorylation. CCL01 also inhibited the activation of mitogen-activated protein kinase (MAPK) signaling and neuroinflammatory processes. Moreover, the metabolite profile-particularly characterized by altered phospholipid metabolism-was significantly changed in the 5xFAD group, while CCL01 partly restored the alteration. Lysophosphatidylcholine (lysoPC), the levels of which were higher in the brains of 5xFAD mice, exerted neurotoxicity in vitro, whereas CCL01 protected neurons from lysoPC-induced toxicity by regulating MAPK signaling. Additionally, CCL01 administration reduced gut inflammation in the 5xFAD mice. In summary, we demonstrated that CCL01 improved the memory function of 5xFAD mice by protecting neurons against Aβ- and lysoPC-induced toxicity through the regulation of MAPK signaling, neuroinflammation, tau phosphorylation, and gut inflammation, suggesting the potential of CCL01 as treatment for AD.

Yomogin, Isolated from Artemisia iwayomogi, Inhibits Neuroinflammation Stimulated by Lipopolysaccharide via Regulating MAPK Pathway

Neuroinflammation causes various neurological disorders, including depression and neurodegenerative diseases. Therefore, regulation of neuroinflammation is a promising therapeutic strategy for inflammation-related neurological disorders. This study aimed to investigate whether yomogin, isolated from Artemisia iwayomogi, has anti-neuroinflammatory effects. First, we evaluated the effects of yomogin by assessing pro-inflammatory mediators and cytokines in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. The results showed that yomogin inhibited the increase in neuroinflammatory factors, including nitric oxide, inducible nitric oxide synthase, cyclooxygenase-2, interleukin-6, and tumor necrosis factor-α, and suppressed phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase and p38, which participate in the mitogen-activated protein kinase (MAPK) pathway. To confirm these effects in vivo, we measured the activation of astrocyte and microglia in LPS-injected mouse brains. Results showed that yomogin treatment decreased astrocyte and microglia activations. Collectively, these results suggest that yomogin suppresses neuroinflammation by regulating the MAPK pathway and it could be a potential candidate for inflammation-mediated neurological diseases.

Duloxetine ameliorates lipopolysaccharide-induced microglial activation by suppressing iNOS expression in BV-2 microglial cells

RATIONALE

It is known that both selective serotonin and serotonin noradrenaline reuptake inhibitors (SSRI, SNRI) are first-line drugs for the treatment of major depressive disorder. It has also been considered that both SSRI and SNRI can improve the symptoms of major depressive disorder by increasing the concentration of monoamine in the synaptic cleft based on the monoamine hypothesis. However, accumulating evidence has indicated that inflammation in the brain may be a key factor in the pathophysiological mechanisms that underlie the development of major depressive disorder.

OBJECTIVES

It has been advocated that microglial cells may regulate the inflammatory response under pathological conditions such as major depressive disorder. In this study, we focused on whether duloxetine can ameliorate the inflammatory response induced by lipopolysaccharide (LPS) in BV-2 microglial cells.

RESULTS

Our results indicated that duloxetine significantly decreased the NO production induced by LPS. The increase in the protein expression level of iNOS induced by LPS was significantly decreased by treatment with duloxetine. Moreover, the increases in the protein expression levels of phosphorylated-IκBα, phosphorylated-Akt and Akt induced by LPS were also significantly decreased. Unexpectedly, the protein expression levels of other pro-inflammatory factors such as COX-2 and the phosphorylation ratios for various molecules including IκBα and Akt were not changed by treatment with duloxetine.

CONCLUSIONS

These findings suggest that duloxetine may have an anti-inflammatory effect, which could contribute to its therapeutic effectiveness for major depressive disorder.

Trichosanthis Semen Suppresses Lipopolysaccharide-Induced Neuroinflammation by Regulating the NF-κB Signaling Pathway and HO-1 Expression in Microglia

Neuroinflammation, which is mediated by microglia that release various inflammatory cytokines, is a typical feature of neurodegenerative diseases (NDDs), such as Alzheimer’s disease and Parkinson’s disease. Hence, alleviating neuroinflammation by downregulating pro-inflammatory action, and upregulating anti-inflammatory action of microglia is an efficient therapeutic target for NDDs. In this study, we evaluated whether trichosanthis semen (TS), a dried ripe seed of Trichosanthes kirilowii Maximowicz, reduces lipopolysaccharide (LPS)-induced neuroinflammation by regulating microglial responses in vitro and in vivo. Our results presented that TS reduced the release of pro-inflammatory mediators, such as nitric oxide (NO), inducible NO synthase, tumor necrosis factor-α, interleukin-1β, and interleukin-6 via inhibition of the nuclear factor kappa B (NF-κB) signaling pathway in LPS-treated BV2 microglial cells. Moreover, TS induced anti-inflammatory mediators, such as interleukin-10, found in inflammatory zone 1, and chitinase 3-like 3 by the upregulation of heme oxygenase 1 (HO-1). We further confirmed that TS administration suppressed microglial activation, but enhanced HO-1 expression in LPS-injected mice. These results suggest that TS has anti-neuroinflammatory effects via inhibition of NF-κB signaling through the activation of HO-1, and that TS may be a therapeutical candidate for NDDs treatment.

Hydrogen Sulfide Ameliorates Lipopolysaccharide-Induced Memory Impairment in Mice by Reducing Apoptosis, Oxidative, and Inflammatory Effects

Hydrogen sulfide (H₂S) is reported to have a neuroprotective activity; however, the role of H₂S in neuroinflammation-induced neuronal damage is ambiguous. Here, we aimed to evaluate the underlying mechanisms for the neuroprotective effect of NaHS, a known H₂S donor, against lipopolysaccharide (LPS)-induced memory impairment (MI). All the treatments were administered for 28 days, and LPS (0.25 mg/kg i.p.) was co-administered intermittently for 7 days from days 15 to 21. Morris water maze (MWM) and Y-maze tests were performed to evaluate MI. Neurodegeneration was histopathologically examined, and the brain homogenates were characterized for reduced glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), tumor necrosis factor (TNF)-α, interleukin (IL)-6, caspase-3, c-Jun, and acetylcholinesterase (AChE) by biochemical analysis. H₂S administration significantly improved spatial and working memory in MWM and Y-maze tasks, respectively. Exogenous H₂S significantly reversed LPS-induced oxidative stress as evidenced by improved GSH, MDA, and SOD levels. H₂S pretreatment significantly attenuated LPS-induced apoptosis and inflammation by decreasing c-Jun and caspase-3 levels and inhibiting TNF-α and IL-6, respectively. The decrease in these markers was supported by H&E and Nissl staining, which confirmed the anti-necrotic activity of H₂S. However, there was no significant improvement in LPS-induced increase in AChE activity. These results indicate that chronic systemic inflammation leads to neurodegeneration and MI and H₂S exerts its neuroprotective effect due to its anti-oxidative, anti-inflammatory, and anti-apoptotic potential via modulation of JNK and extrinsic apoptosis pathways.

Ginsenoside Rg1 alleviates lipopolysaccharide-induced neuronal damage by inhibiting NLRP1 inflammasomes in HT22 cells

Lipopolysaccharide (LPS) is a toxic component of cell walls of Gram-negative bacteria that are widely present in gastrointestinal tracts. Increasing evidence showed that LPS plays important roles in the pathogeneses of neurodegenerative disorders, such as Alzheimer's disease (AD). NADPH oxidase s2 (NOX2) is a complex membrane protein that contributes to the production of reactive oxygen species (ROS) in several neurological diseases. The NLRP1 inflammasome can be activated in response to an accumulation of ROS in neurons. However, it is still unknown whether LPS exposure can deteriorate neuronal damage by activating NOX2-NLRP1 inflammasomes. Ginsenoside Rg1 (Rg1) has protective effects on neurons, although whether Rg1 alleviates LPS-induced neuronal damage by inhibiting NOX2-NLRP1 inflammasomes remains unclear. In the present study, the effect of concentration gradients and different times of LPS exposure on neuronal damage was investigated in HT22 cells, and further observed the effect of Rg1 treatment on NOX2-NLPR1 inflammasome activation, ROS production and neuronal damage in LPS-treated HT22 cells. The results demonstrated that LPS exposure significantly induced NOX2-NLRP1 inflammasome activation, excessive production of ROS, and neuronal damage in HT22 cells. It was also shown that Rg1 treatment significantly decreased NOX2-NLRP1 inflammasome activation and ROS production and alleviated neuronal damage in LPS-induced HT22 cells. The present data suggested that Rg1 has protective effects on LPS-induced neuronal damage by inhibiting NOX2-NLRP1 inflammasomes in HT22 cells, and Rg1 may be a potential therapeutic approach for delaying neuronal damage in AD.

Artemisiae Iwayomogii Herba inhibits lipopolysaccharide-induced neuroinflammation by regulating NF-κB and MAPK signaling pathways

BACKGROUND

Neuroinflammation plays a major role in the development of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. The regulation of microglia is an efficient therapeutic approach to controlling neuroinflammation.

PURPOSE

In this study, we aimed to determine whether Artemisiae Iwayomogii Herba (AIH), which is herbal medicine traditionally used for inflammation-related disorders, controls neuroinflammatory responses by regulating the microglia-mediated signaling pathway.

METHODS

BV-2 microglial cells were treated with AIH and lipopolysaccharides (LPS), then various pro-inflammatory mediators were analyzed using griess reaction, quantitative reverse-transcription polymerase chain reaction, or western blotting. C57BL/6 J mice were orally administered by AIH for 17 days and intraperitoneally injected with LPS for the last 14 days. The brains were collected and the microglial activation and nucleotide-binding oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing 3 (NLRP3) expression in the cortex and hippocampus were analyzed using immunohistochemistry or western blotting.

RESULTS

In BV-2 microglial cells, we found that AIH inhibited nitric oxide (NO) production induced by LPS. AIH also suppressed the expressions of pro-inflammatory mediators, including inducible NO synthase, cyclooxygenase-2, tumor necrosis factor-α, and interleukin-6. The study also revealed that the effects of AIH are related to the regulation of the nuclear factor kappa B (NF-κB) and the mitogen-activated protein kinase (MAPK) signaling pathway. Additionally, we found that AIH prevented the formation of NLRP3 inflammasomes. Consistent with the results of in vitro studies on the brains of LPS-injected mice, we observed that AIH suppressed microglial activation and NLRP3 expression.

CONCLUSION

Taken together, these results suggest that AIH attenuates neuroinflammation by regulating the NF-κB and MAPK pathways, and it may be used for treating neurological diseases.

Cuscutae Japonicae Semen Ameliorates Memory Dysfunction by Rescuing Synaptic Damage in Alzheimer's Disease Models

Alzheimer's disease (AD) is the most common type of dementia in the elderly. It is characterized by the accumulation of amyloid-beta (Aβ) and progressive cognitive impairment. To alleviate the symptoms of AD, functional foods and nutrients have been used for centuries. In this study, we investigated whether Cuscutae Japonicae Semen (CJS), a medicinal food traditionally used in East Asia, has effects on memory improvement and synapse protection in AD. We orally administered CJS to 5x familiar AD (5xFAD) transgenic mice and performed the Morris water maze test. The results showed that CJS treatment ameliorated the decline of memory function. Then, we demonstrated that CJS attenuated the degeneration of pre- and post-synaptic proteins in the hippocampi of 5xFAD mice. To demonstrate the effects of CJS in vitro, we treated Aβ in primary neuronal culture with CJS and observed that CJS rescued the loss of functional synapses. The protective effects of CJS on the synapse were due to the inhibition of activated caspase-3 expression. Additionally, CJS inhibited the phosphorylation of glycogen synthase kinase-3β and tau proteins, which contribute to synaptic dysfunction. Taken together, our results suggest that CJS is efficient in alleviating memory loss by rescuing caspase-3-mediated synaptic damage in AD treatment.