Isoformononetin, a dietary isoflavone protects against streptozotocin induced rat model of neuroinflammation through inhibition of NLRP3/ASC/IL-1 axis activation

Neuroprotective potential of tranilast in streptozotocin-induced sporadic Alzheimer's disease model targeting TXNIP-NLRP3 inflammasome pathway

Sporadic Alzheimer's disease (sAD) is a progressive neurodegenerative disorder characterised by oxidative stress, neuroinflammation, mitochondrial dysfunction and cerebral insulin resistance. Even though approximately 95 % of AD cases are reported as sporadic, the exact pathogenesis remains sparse. Tranilast, an analogue of tryptophan metabolite, was initially endowed as an anti-allergic agent and used in multiple inflammatory ailments. Still, the molecular mechanisms targeting sAD are yet to be investigated. In the present study, we investigated the neuroprotective potential of tranilast by performing biochemical, molecular and histopathological assessments using both in vivo and in vitro experimental sAD models. Streptozotocin (STZ; 3 mg/kg) was bilaterally injected on day 1 and 3 through the intracerebroventricular (ICV) route to Sprague Dawley rats for the in vivo model induction. Spontaneous alternation test, novel object recognition test, and passive avoidance test were performed to assess the altered behavioural patterns in animals. Furthermore, human neuroblastoma cells (SHSY5Y) were exposed to STZ (1 mM) and tranilast for 24 h to validate the in vivo results. Three weeks of tranilast (30 and 100 mg/kg, p.o.) treatment improved neurobehavioural anomalies in ICV-STZ-treated rats by halting neuroinflammation and NLRP3 inflammasome activation caused by enhanced reactive oxygen species (ROS) and thioredoxin interaction protein (TXNIP) overexpression. The phosphorylated tau (p-tau S416) level was also increased in the ICV-STZ rat's hippocampus and reversed upon tranilast treatment. A high dose of tranilast (100 mg/kg) treatment sensitised hippocampal insulin signalling in ICV-STZ-treated rats. Furthermore, in cell culture studies, 24-h tranilast (30 and 100 μM) treatment reduced the mitochondrial ROS production and attenuated inflammasome activation in STZ-treated SHSY5Y cells. In summary, the findings of the study proclaim the neuroprotective potential of tranilast in STZ induced model of sAD by modulating the TXNIP-NLRP3 inflammasome pathway.

Flavonoids in the regulation of microglial-mediated neuroinflammation; focus on fisetin, rutin, and quercetin

Neuroinflammation is a critical mechanism in central nervous system (CNS) inflammatory disorders, encompassing conditions such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), multiple sclerosis (MS), traumatic brain injury (TBI), encephalitis, spinal cord injury (SCI), and cerebral stroke. Neuroinflammation is characterized by increased blood vessel permeability, leukocyte infiltration, glial cell activation, and elevated production of inflammatory mediators, such as chemokines and cytokines. Microglia act as the resident macrophages of the central nervous system, serving as the principal defense mechanism in brain tissue. After CNS injury, microglia modify their morphology and downregulate genes that promote homeostatic functions. Despite comprehensive transcriptome analyses revealing specific gene modifications in "pathological" microglia, microglia's precise protective or harmful functions in neurological disorders remain insufficiently comprehended. Accumulating data suggests that the polarization of microglia into the M1 proinflammatory phenotype or the M2 antiinflammatory phenotype may serve as a sensible therapeutic strategy for neuroinflammation. Flavonoids, including rutin, fisetin, and quercetin, function as crucial chemical reservoirs with unique structures and diverse actions and are extensively used to modulate microglial polarization in treating neuroinflammation. This paper highlights the detrimental effects of neuroinflammation seen in neurological disorders such as stroke. Furthermore, we investigate their therapeutic benefits in alleviating neuroinflammation via the modulation of macrophage polarization.

Aerobic exercise and metformin attenuate the cognitive impairment in an experimental model of type 2 diabetes mellitus: focus on neuroinflammation and adult hippocampal neurogenesis

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder that increases the prevalence of cognitive impairment in the geriatric population. Aerobic exercise is an excellent non-pharmacological therapeutic strategy to prevent Alzheimer's disease, the most common form of dementia. The exact molecular mechanism of aerobic exercise (Exe) as an intervention to counter cognitive decline is far from clear. Metformin is a first-line agent against T2DM with neuroprotective properties. The present study assessed the role of treadmill exercise in combination with a low dose of metformin (Met; 70 mg/kg) in cognitive impairment and its associated molecular mechanism in T2DM rats. The experimental model of T2DM-associated cognitive decline was created by administration of a high-fat diet (HFD) with a low dose of streptozotocin (STZ; 35 mg/kg). Neurobehavioral assessments were performed to evaluate spatial recognition and fear-conditioned memory across the groups: control, HFD + STZ, HFD + STZ + Exe, and HFD + STZ + Exe + Met. In addition, we performed immunohistochemistry and western blotting on the rat hippocampal tissue from the above groups for protein expression studies. T2DM rats showed a significant cognitive decline compared to the control group, which improved in the long-term exercise and metformin co-administered animals. The level of neuroinflammation was significantly elevated in the hippocampal tissue of T2DM rats compared to the control and lowered after exercise and metformin treatment. T2DM reduced mature neurons and neurogenesis while increasing astrogliosis and microgliosis, ameliorated by exercise and metformin treatment. Moreover, T2DM impaired hippocampal neurogenesis by reducing the canonical Wnt/β-catenin pathway, which got upregulated in exercise and metformin-co-administered rats. Long-term aerobic exercise with metformin treatment ameliorated neuroinflammation and promoted adult hippocampal neurogenesis via upregulating the canonical Wnt/β-catenin pathway in T2DM rats.

Integration of serum pharmacochemistry and metabolomics to reveal the underlying mechanism of shaoyao-gancao-fuzi decoction to ameliorate rheumatoid arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

For centuries, Shaoyao-Gancao-Fuzi decoction (SGFD) has been a reliable traditional Chinese medicine for treating rheumatoid arthritis (RA). Despite its long history of use, the specific active components and underlying mechanisms of its therapeutic effects have yet to be fully understood.

AIM OF THE STUDY

The aim of this study was to investigate the active ingredients and therapeutic effects of SGFD on RA, and to further understand its underlying mechanism.

MATERIALS AND METHODS

The chemical constituents in SGFD extract and in rat serum after oral administration of SGFD were identified and evaluated using ultra-performance liquid chromatography quadrupole-time-flight mass spectrometry (UPLC-Q-TOF/MS) together with various data-processing methods, respectively. The efficacy of SGFD was assessed by using an adjuvant-induced arthritis (AIA) rat model and lipopolysaccharide-stimulated RAW 264.7 cell. Subsequently, cell metabolomic was conducted to clarify the potential biomarkers and pathways. ELISA, RT-qPCR, and WB were used to verify the anti-arthritis mechanism of SGFD.

RESULTS

A total of 65 chemical constituents were identified in SGFD. 17 active components were distinguished in rat serum samples, of which 13 may be the main active ingredients for SGFD treatment of RA. The remarkable efficacy of SGFD in reducing the symptoms of RA is evident through its ability to alleviate the redness and swelling of the affected paws, as well as reduce the infiltration of inflammatory cells. Cell experiments revealed that rat serum of SGFD reduced IL-1β, IL-6, and TNF-α secretion in RAW 264.7 cells. 27 potential biomarkers were identified through cell metabolomics analysis. The arachidonic acid (AA) metabolism signaling pathway was activated in RA, which could be reversed by rat serum of SGFD. SGFD effectively inhibited the expression and transformation of AA by downregulating the expression of key enzymes, including phospholipase A and cyclooxygenase.

CONCLUSION

SGFD may ameliorate RA symptoms by regulating the AA-PGH2-PGE2/PGF2α pathway. The main active components include songorine, fuziline, neoline, albiflorin, paeoniflorin, liquiritin, benzoylmesaconine, isoformononetin, liquiritigenin, isoliquiritigenin, formononetin, glycyrrhizic acid, and glycyrrhetinic acid.

LC-MS/MS analysis of Shenghui decoction component and its effect on learning and memory and neuroprotection in sleep deprivation model mice

BACKGROUND

In recent years, sleep problems have emerged as a significant factor in the development of diseases that influence cognitive function. The inflammatory response may have a role in the neurobiological processes of sleep deprivation, resulting in impairment of memory and learning. Shenghui Decoction (SHD) is a classic formula in Chinese medicine used to treat forgetfulness and insomnia. However, it remains unclear whether the anti-inflammatory effects of SHD are specifically linked to the inhibition of P2X7R and p38MAPK.

METHODS

Analysis of chemical constituents of Shenghui Decoction based on UPLC-Q-TOF-MS / MS. The learning and memory competency of the mice was assessed using the new object recognition and Morris water maze tests. The morphology of hippocampus neurons was observed using HE staining, and the expression of inflammatory factors was measured using ELISA and immunofluorescence. The expression of P2X7R and p38MAPK in the hippocampus was analyzed via real-time PCR and Western blotting. Additionally, the components absorbed into the bloodstream of SHD were analyzed.

RESULTS

The study found that SHD contains 47 chemical constituents, including phenolic acids, flavonoids, iridoids, and triterpenoids. In addition, it was observed that SHD significantly improved the learning and memory abilities of the mice. SHD also improved the morphology of hippocampus neurons. The expression of inflammatory factors was decreased in the SHD-treated mice. Additionally, the expression of P2X7R and p38MAPK was decreased in the hippocampus of the SHD-treated mice. Fifteen prototype chemical constituents were detected in blood.

CONCLUSIONS

The study suggests that SHD could be a viable treatment for cognitive impairments associated with brain inflammation. The therapeutic effects of SHD are likely due to its chemical components, including phenolic acids, flavonoids, iridoids, and triterpenoids. SHD can improve learning and memory impairment caused by sleep deprivation through the P2X7R/p38MAPK inflammatory signaling pathways.

SIRT1 slows the progression of lupus nephritis by regulating the NLRP3 inflammasome through ROS/TRPM2/Ca2+ channel

Systemic lupus erythematosus (SLE) is a chronic multisystem inflammatory disease associated with autoantibody formation. Lupus nephritis (LN) is one of the most severe organ manifestations of SLE. The inflammatory response is a key factor in kidney injury, and the NLRP3 inflammasome is frequently associated with the pathogenesis of LN. Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD +)-dependent histone deacetylase, is a promising therapeutic target for preventing renal injury. However, the mechanism of SIRT1 in LN remains unclear. Here, we aimed to investigate the mechanism by which SIRT inhibits the NLRP3 inflammasome to slow the progression of LN. We detected the expression of SIRT1 and the infiltration of macrophages in MRL/lpr mice; the results showed that the expression of SIRT1 was decreased, and the symptoms of lupus nephritis were relieved after the use of resveratrol, which upregulated SIRT1. In vitro studies showed that after lipopolysaccharide (LPS) stimulation, SIRT1 expression decreased, and the NLRP3 inflammasome was activated. Upregulation of SIRT1 inhibits NLRP3 inflammasome activation and assembly by interfering with two signalling pathways. First, SIRT1 affects NF-κB expression, transcription, and inflammatory cytokine expression. Second, SIRT1 modulates calcium influx induced by transient receptor potential channel M2 (TRPM2), which could be partly due to the inhibition of reactive oxygen species (ROS) production. Our findings suggest that upregulated SIRT1 inhibits the NLRP3 inflammasome to slow the progression of lupus nephritis by regulating NF-κB and ROS/TRPM2/Ca2+ channels. This study reveals a new anti-inflammatory mechanism of SIRT1, suggesting that SIRT1 may be a potential therapeutic target for the prevention of LN.

NLRP3 Inflammasome’s Activation in Acute and Chronic Brain Diseases—An Update on Pathogenetic Mechanisms and Therapeutic Perspectives with Respect to Other Inflammasomes

Increasingly prevalent acute and chronic human brain diseases are scourges for the elderly. Besides the lack of therapies, these ailments share a neuroinflammation that is triggered/sustained by different innate immunity-related protein oligomers called inflammasomes. Relevant neuroinflammation players such as microglia/monocytes typically exhibit a strong NLRP3 inflammasome activation. Hence the idea that NLRP3 suppression might solve neurodegenerative ailments. Here we review the recent Literature about this topic. First, we update conditions and mechanisms, including RNAs, extracellular vesicles/exosomes, endogenous compounds, and ethnic/pharmacological agents/extracts regulating NLRP3 function. Second, we pinpoint NLRP3-activating mechanisms and known NLRP3 inhibition effects in acute (ischemia, stroke, hemorrhage), chronic (Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, MS, ALS), and virus-induced (Zika, SARS-CoV-2, and others) human brain diseases. The available data show that (i) disease-specific divergent mechanisms activate the (mainly animal) brains NLRP3; (ii) no evidence proves that NLRP3 inhibition modifies human brain diseases (yet ad hoc trials are ongoing); and (iii) no findings exclude that concurrently activated other-than-NLRP3 inflammasomes might functionally replace the inhibited NLRP3. Finally, we highlight that among the causes of the persistent lack of therapies are the species difference problem in disease models and a preference for symptomatic over etiologic therapeutic approaches. Therefore, we posit that human neural cell-based disease models could drive etiological, pathogenetic, and therapeutic advances, including NLRP3’s and other inflammasomes’ regulation, while minimizing failure risks in candidate drug trials.

Beneficial effects of natural flavonoids on neuroinflammation

Neuroinflammation is the fundamental immune response against multiple factors in the central nervous system and is characterized by the production of inflammatory mediators, activated microglia and astrocytes, and the recruitment of innate and adaptive immune cells to inflammatory sites, that contributes to the pathological process of related brain diseases, such as Alzheimer’s disease, Parkinson’s disease, depression, and stroke. Flavonoids, as a species of important natural compounds, have been widely revealed to alleviate neuroinflammation by inhibiting the production of pro-inflammatory mediators, elevating the secretion of anti-inflammatory factors, and modulating the polarization of microglia and astrocyte, mainly via suppressing the activation of NLRP3 inflammasome, as well as NF-κB, MAPK, and JAK/STAT pathways, promoting Nrf2, AMPK, BDNF/CREB, Wnt/β-Catenin, PI3k/Akt signals and SIRT1-mediated HMGB1 deacetylation. This review will provide the latest and comprehensive knowledge on the therapeutic benefits and mechanisms of natural flavonoids in neuroinflammation, and the natural flavonoids might be developed into food supplements or lead compounds for neuroinflammation-associated brain disorders.

Flavonoids bridging the gut and the brain: intestinal metabolic fate, and direct or indirect effects of natural supporters against neuroinflammation and neurodegeneration

In recent years, experimental evidence suggested a possible role of the gut microbiota in the onset and development of several neurodegenerative disorders, such as AD and PD, MS and pain. Flavonoids, including anthocyanins, EGCG, the flavonol quercetin, and isoflavones, are plant polyphenolic secondary metabolites that have shown therapeutic potential for the treatment of various pathological conditions, including neurodegenerative diseases. This is due to their antioxidant and anti-inflammatory properties, despite their low bioavailability which often limits their use in clinical practice. In more recent years it has been demonstrated that flavonoids are metabolized by specific bacterial strains in the gut to produce their active metabolites. On the other way round, both naturally-occurring flavonoids and their metabolites promote or limit the proliferation of specific bacterial strains, thus profoundly affecting the composition of the gut microbiota which in turn modifies its ability to further metabolize flavonoids. Thus, understanding the best way of acting on this virtuous circle is of utmost importance to develop innovative approaches to many brain disorders. In this review, we summarize some of the most recent advances in preclinical and clinical research on the neuroinflammatory and neuroprotective effects of flavonoids on AD, PD, MS and pain, with a specific focus on their mechanisms of action including possible interactions with the gut microbiota, to emphasize the potential exploitation of dietary flavonoids as adjuvants in the treatment of these pathological conditions.

Study on the Mechanism of Üstikuddus Sherbiti in Ischemic Cerebrovascular Diseases: Based on Network Pharmacology

This paper aims to study the potential biological mechanism of Üstikuddus Sherbiti (ÜS) in the treatment of ischemic cerebrovascular diseases (ICVD) by the network pharmacology method. Traditional Chinese Medicine Systems Pharmacology (TCMSP) database was used to obtain effective constituents of ÜS by screening eligible oral utilization, drug similarity, and blood-brain barrier permeability threshold. By drug target prediction and stroke treatment target mining, 2 target data sets were analyzed to find intersection targets and the corresponding constituents were used as active constituents. An active constituent target network and an effective constituent target network were constructed by using Cytoscape 3.7.2 software. Degree parameters of the effective constituent target network were analyzed to find important effective constituents and targets. Through protein-protein interaction (PPI) analysis/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, potential signaling pathways of ÜS in ischemic stroke were found out. AutoDock was used for molecular docking verification. A total of 90 active constituents of ÜS were screened out. There were 10 active constituents against ICVD, including quercetin, luteolin, kaempferol, and naringenin, and 10 important targets for anticerebral ischemia, namely, PIK3CA, APP, PIK3R1, MAPK1, MAPK3, AKT1, PRKCD, Fyn, RAC1, and NF-κB1. Based on the protein interaction network, the important targets of ÜS were significantly enriched in PI3K-Akt signaling pathway, neuroactive ligand-receptor interaction pathway, Ras signaling pathway, etc. ÜS in ICVD has characteristics like multiple targets, multiple approaches, and multiple pathways. Results of molecular docking showed that the active components in ICVD had a good binding ability with the key targets. Its main biological mechanism may be related to the PI3K-Akt and Ras-MAPK centered signaling pathway. Our study demonstrated that ÜS exerted the effect of treating ICVD by regulating multiple targets and multiple channels with multiple components through the method of network pharmacology and molecular docking.