Sodium butyrate inhibits high cholesterol-induced neuronal amyloidogenesis by modulating NRF2 stabilization-mediated ROS levels: involvement of NOX2 and SOD1

The potential role of gut microbiota-derived metabolites as regulators of metabolic syndrome-associated mitochondrial and endolysosomal dysfunction in Alzheimer's disease

Although the role of gut microbiota (GMB)-derived metabolites in mitochondrial and endolysosomal dysfunction in Alzheimer's disease (AD) under metabolic syndrome remains unclear, deciphering these host-metabolite interactions represents a major public health challenge. Dysfunction of mitochondria and endolysosomal networks (ELNs) plays a crucial role in metabolic syndrome and can exacerbate AD progression, highlighting the need to study their reciprocal regulation for a better understanding of how AD is linked to metabolic syndrome. Concurrently, metabolic disorders are associated with alterations in the composition of the GMB. Recent evidence suggests that changes in the composition of the GMB and its metabolites may be involved in AD pathology. This review highlights the mechanisms of metabolic syndrome-mediated AD development, focusing on the interconnected roles of mitochondrial dysfunction, ELN abnormalities, and changes in the GMB and its metabolites. We also discuss the pathophysiological role of GMB-derived metabolites, including amino acids, fatty acids, other metabolites, and extracellular vesicles, in mediating their effects on mitochondrial and ELN dysfunction. Finally, this review proposes therapeutic strategies for AD by directly modulating mitochondrial and ELN functions through targeting GMB metabolites under metabolic syndrome.

The Role of Short Chain Fatty Acids in Inflammation and Body Health

Short chain fatty acids (SCFAs), mainly including acetate, propionate and butyrate, are produced by intestinal bacteria during the fermentation of partially digested and indigestible polysaccharides. SCFAs play an important role in regulating intestinal energy metabolism and maintaining the homeostasis of the intestinal environment and also play an important regulatory role in organs and tissues outside the gut. In recent years, many studies have shown that SCFAs can regulate inflammation and affect host health, and two main signaling mechanisms have also been identified: the activation of G-protein coupled receptors (GPCRs) and inhibition of histone deacetylase (HDAC). In addition, a growing body of evidence highlights the importance of every SCFA in influencing health maintenance and disease development. In this review, we summarized the recent advances concerning the biological properties of SCFAs and their signaling pathways in inflammation and body health. Hopefully, it can provide a systematic theoretical basis for the nutritional prevention and treatment of human diseases.

Sodium butyrate ameliorates high glucose-suppressed neuronal mitophagy by restoring PRKN expression via inhibiting the RELA-HDAC8 complex

Damaged mitochondria accumulation in diabetes is one of the main features that contribute to increased incidence of cognitive impairment by inducing apoptosis. Butyrate is a major metabolite produced by microbiota that has neuroprotective effects by regulating mitochondrial function. However, detailed mechanisms underlying how butyrate can regulate neuronal mitophagy remain unclear. Here, we examined the regulatory effects of sodium butyrate (NaB) on high glucose-induced mitophagy dysregulation, neuronal apoptosis, and cognitive impairment and its underlying mechanisms in human-induced pluripotent stem cell-derived neurons, SH-SY5Ys, and streptozotocin (STZ)-induced diabetic mice. In our results, diabetic mice showed gut-microbiota dysbiosis, especially a decreased number of butyrate-producing bacteria and reduced NaB plasma concentration. NaB ameliorated high glucose-induced neuronal mitochondrial dysfunction by recovering PRKN/Parkin-mediated mitophagy. High glucose-induced reactive oxygen species (ROS) and -inhibited PRKAA/AMPKα stimulated the RELA/p65-HDAC8 complex, which downregulated PRKN protein expression by binding to the PRKN promoter region. NaB restored PRKN expression by blocking RELA nuclear translocation and directly inhibiting HDAC8 in the nucleus. In addition, HDAC8 overexpression inhibited the positive effect of NaB on high glucose-induced mitophagy dysfunction and neuronal apoptosis. Oral administration of NaB improved cognitive impairment in diabetic mice by restoring mitophagy in the hippocampus. Taken together, NaB ameliorates neuronal mitophagy through PRKN restoration by inhibiting RELA-HDAC8 complexes, suggesting that NaB is an important substance for protecting neuronal apoptosis in diabetes-associated cognitive impairment.

Sodium butyrate alleviates experimental autoimmune prostatitis by inhibiting oxidative stress and NLRP3 inflammasome activation via the Nrf2/HO-1 pathway

BACKGROUND

Chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS) leads to severe discomfort in males and loss of sperm quality. Current therapeutic options have failed to achieve satisfactory results. Sodium butyrate (NaB) plays a beneficial role in reducing inflammation, increasing antioxidant capacities, and improving organ dysfunction; additionally NaB has good safety prospects and great potential for clinical application. The purpose of the current research was to study the effect of NaB on CP/CPPS and the underlying mechanisms using a mouse model of experimental autoimmune prostatitis (EAP) mice.

METHODS

The EAP mouse model was successfully established by subcutaneously injecting a mixture of prostate antigen and complete Freund's adjuvant. Then, EAP mice received daily intraperitoneal injections of NaB (100, 200, or 400 mg/kg/day) for 16 days, from Days 26 to 42. We then explored anti-inflammatory potential mechanisms of NaB by studying the effects of Nrf2 inhibitor ML385 and HO-1 inhibitor zinc protoporphyrin on prostate inflammation and pelvic pain using this model. On Day 42, hematoxylin-eosin staining and dihydroethidium staining were used to evaluate the histological changes and oxidative stress levels of prostate tissues. Chronic pelvic pain was assessed by applying Von Frey filaments to the lower abdomen. The levels of inflammation-related cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor were detected by enzyme-linked immunosorbent assay. The regulation of Nrf2/HO-1 signaling pathway and the expression of NLRP3 inflammasome-related protein in EAP mice were detected by western blot analysis assay.

RESULTS

Compared with the EAP group, chronic pain development, histological manifestations, and cytokine levels showed that NaB reduced the severity of EAP. NaB treatment could inhibit NLRP3 inflammasome activation. Mechanism studies showed that NaB intervention could alleviate oxidative stress in EAP mice through Nrf2/HO-1 signal pathway. Nrf2/HO-1 pathway inhibitors can inhibit NaB -mediated oxidative stress. The inhibitory effect of NaB on the activation of NLRP3 inflammasome and anti-inflammatory effect can also be blocked by Nrf2/HO-1 pathway.

CONCLUSIONS

NaB treatment can alleviates prostatic inflammation and pelvic pain associated with EAP by inhibiting oxidative stress and NLRP3 inflammasome activation via the Nrf2/HO-1 pathway. NaB has the potential as an effective agent in the treatment of EAP.

Epigenetics of Alzheimer’s Disease: Past, Present and Future

Alzheimer’s disease (AD) exemplifies a looming epidemic lacking effective treatment and manifests with the accumulation of neurofibrillary tangles, amyloid-β plaques, neuroinflammation, behavioral changes, and acute cognitive impairments. It is a complex, multifactorial disorder that arises from the intricate interaction between environment and genetic factors, restrained via epigenetic machinery. Though the research progress has improved the understanding of clinical manifestations and disease advancement, the causal mechanism of detrimental consequences remains undefined. Despite the substantial improvement in recent diagnostic modalities, it is challenging to distinguish AD from other forms of dementia. Accurate diagnosis is a major glitch in AD as it banks on the symptoms and clinical criteria. Several studies are underway in exploring novel and reliable biomarkers for AD. In this direction, epigenetic alterations have transpired as key modulators in AD pathogenesis with the impeding inferences for the management of this neurological disorder. The present chapter aims to discuss the significance of epigenetic modifications reported in the pathophysiology of AD such as DNA methylation, hydroxy-methylation, methylation of mtDNA, histone modifications, and noncoding RNAs. Additionally, the chapter also describes the possible therapeutic avenues that target epigenetic modifications in AD.

The influence of microbiota on ferroptosis in intestinal diseases

Ferroptosis is a distinctive form of iron-dependent necrotic cell death, characterized by excessive lipid peroxidation on cellular membranes and compromised cellular antioxidant defenses. Multiple metabolic pathways, including iron and lipid metabolism, as well as antioxidant systems, contribute to the execution of ferroptosis. The gut microbiota exerts regulatory effects on ferroptosis through its microbial composition, biological functions, and metabolites. Notably, most pathogenic bacteria tend to promote ferroptosis, thereby inducing or exacerbating diseases, while most probiotics have been shown to protect against cell death. Given microbiota colonization in the gut, an intimate association is found between intestinal diseases and microbiota. This review consolidates the essential aspects of ferroptotic processes, emphasizing key molecules and delineating the intricate interplay between gut microbiota and ferroptosis. Moreover, this review underscores the potential utility of gut microbiota modulation in regulating ferroptosis for the treatment of intestinal diseases.

Butyrate protects against MRSA pneumonia via regulating gut-lung microbiota and alveolar macrophage M2 polarization

IMPORTANCE

Pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) continues to carry a high burden in terms of mortality. With the roles of gut microbiota in mediating lung diseases being gradually uncovered, the details of the molecular mechanism of the "gut-lung axis" mediated by beneficial microorganisms and small-molecule metabolites have gradually attracted the attention of researchers. However, further studies are still necessary to determine the efficacy of microbial-based interventions. Our findings indicate that sodium butyrate (NaB) alleviates MRSA-induced pulmonary inflammation by improving gut-lung microbiota and promoting M2 polarization of alveolar macrophages. Therefore, the preventive administration of NaB might be explored as an effective strategy to control MRSA pneumonia.

Impact of Donepezil Supplementation on Alzheimer's Disease-like Pathology and Gut Microbiome in APP/PS1 Mice

Based on published information, the occurrence and development of Alzheimer's disease (AD) are potentially related to gut microbiota changes. Donepezil hydrochloride (DH), which enhances cholinergic activity by blocking acetylcholinesterase (AChE), is one of the first-line drugs for AD treatment approved by the Food and Drug Administration (FDA) of the USA. However, the potential link between the effects of DH on the pathophysiological processes of AD and the gut microbiota remains unclear. In this study, pathological changes in the brain and colon, the activities of superoxide dismutase (SOD) and AChE, and changes in intestinal flora were observed. The results showed that Aβ deposition in the prefrontal cortex and hippocampus of AD mice was significantly decreased, while colonic inflammation was significantly alleviated by DH treatment. Concomitantly, SOD activity was significantly improved, while AChE was significantly reduced after DH administration. In addition, the gut microbiota community composition of AD mice was significantly altered after DH treatment. The relative abundance of Akkermansia in the AD group was 54.8% higher than that in the N group. The relative abundance of Akkermansia was increased by 18.3% and 53.8% in the AD_G group and the N_G group, respectively. Interestingly, Akkermansia showed a potential predictive value and might be a biomarker for AD. Molecular docking revealed the binding mode and major forces between DH and membrane proteins of Akkermansia. The overall results suggest a novel therapeutic mechanism for treating AD and highlight the critical role of gut microbiota in AD pathology.

Metabolic Profile of Alzheimer's Disease: Is 10-Hydroxy-2-decenoic Acid a Pertinent Metabolic Adjuster?

Alzheimer's disease (AD) represents a significant public health concern in modern society. Metabolic syndrome (MetS), which includes diabetes mellitus (DM) and obesity, represents a modifiable risk factor for AD. MetS and AD are interconnected through various mechanisms, such as mitochondrial dysfunction, oxidative stress, insulin resistance (IR), vascular impairment, inflammation, and endoplasmic reticulum (ER) stress. Therefore, it is necessary to seek a multi-targeted and safer approach to intervention. Thus, 10-hydroxy-2-decenoic acid (10-HDA), a unique hydroxy fatty acid in royal jelly, has shown promising anti-neuroinflammatory, blood-brain barrier (BBB)-preserving, and neurogenesis-promoting properties. In this paper, we provide a summary of the relationship between MetS and AD, together with an introduction to 10-HDA as a potential intervention nutrient. In addition, molecular docking is performed to explore the metabolic tuning properties of 10-HDA with associated macromolecules such as GLP-1R, PPARs, GSK-3, and TREM2. In conclusion, there is a close relationship between AD and MetS, and 10-HDA shows potential as a beneficial nutritional intervention for both AD and MetS.

Berberine ameliorates iron levels and ferroptosis in the brain of 3 × Tg-AD mice

BACKGROUND

Berberine (BBR) is a natural alkaloid extracted from the herb Coptis chinensis. This compound has the ability to penetrate the blood-brain barrier (BBB) and exhibit neuroprotective value in the treatment of Alzheimer's disease (AD). AD is a neurodegenerative disease characterized by β-amyloid (Aβ) deposition, hyperphosphorylated tau and other characters. Iron accumulation and ferroptosis were also detected in AD brain, which can result in neuronal damage. However, it is still unclear whether BBR can suppress ferroptosis in AD and alleviate its underlying pathology.

PURPOSE

This study investigated whether BBR may affect ferroptosis and related signaling pathways in triple transgenic AD (3 × Tg-AD) mice.

METHODS

Four-month-old 3 × Tg-AD mice received oral administration of BBR at a dose of 50 mg/kg for 7.5 months. Cognitive function and anxiety levels in mice were assessed using the morris water maze test, open field test, and novel object recognition test. Western blot, immunohistochemistry, and ICP-MS were employed to assess the pathology of AD, brain iron metabolism, and ferroptosis signaling pathways. Transmission electron microscopy was used to detect mitochondrial changes. The synergistic effects of BBR combined with Nrf2 were investigated using molecular docking programs and surface plasmon resonance technology. Co-inmunoprecipitation assay was used to examine the effect of BBR on the binding ability of Nrf2 and Keap1.

RESULTS

The results indicated that chronic treatment of BBR mitigated cognitive disorders in 3 × Tg-AD model mice. Reductions in Aβ plaque, hyperphosphorylated tau protein, neuronal loss, and ferroptosis in the brains of 3 × Tg-AD mice suggested that BBR could alleviate brain injury. In addition, BBR treatment attenuated ferroptosis, as evidenced by decreased levels of iron, MDA, and ROS, while enhancing SOD, GSH, GPX4, and SLC7A11. Consistent with the in vivo assay, BBR inhibited RSL3-induced ferroptosis in N2a-sw cells. BBR increased the expression levels of GPX4, FPN1 and SLC7A11 by regulating Nrf2 transcription levels, thereby inhibiting ferroptosis. Molecular docking programs and surface plasmon resonance technology demonstrated the direct combination of BBR with Nrf2. Co-inmunoprecipitation analysis showed that BBR inhibited the interaction between Keap1 and Nrf2.

CONCLUSION

For the first time, these results showed that BBR could inhibit iron levels and ferroptosis in the brains of 3 × Tg-AD model mice and partially protect against RSL3-induced ferroptosis via the activation of Nrf2 signaling.

Short-Chain Fatty Acids in the Microbiota-Gut-Brain Axis: Role in Neurodegenerative Disorders and Viral Infections

The gut-brain axis (GBA) is the umbrella term to include all bidirectional communication between the brain and gastrointestinal (GI) tract in the mammalian body. Evidence from over two centuries describes a significant role of GI microbiome in health and disease states of the host organism. Short-chain fatty acids (SCFAs), mainly acetate, butyrate, and propionate that are the physiological forms of acetic acid, butyric acid, and propionic acid respectively, are GI bacteria derived metabolites. SCFAs have been reported to influence cellular function in multiple neurodegenerative diseases (NDDs). In addition, the inflammation modulating properties of SCFAs make them suitable therapeutic candidates in neuroinflammatory conditions. This review provides a historical background of the GBA and current knowledge of the GI microbiome and role of individual SCFAs in central nervous system (CNS) disorders. Recently, a few reports have also identified the effects of GI metabolites in the case of viral infections. Among these viruses, the flaviviridae family is associated with neuroinflammation and deterioration of CNS functions. In this context, we additionally introduce SCFA based mechanisms in different viral pathogenesis to understand the former's potential as agents against flaviviral disease.

Mechanisms of Blood-Brain Barrier Protection by Microbiota-Derived Short-Chain Fatty Acids

Impairment of the blood-brain barrier (BBB) integrity is implicated in the numerous neurological disorders associated with neuroinflammation, neurodegeneration and aging. It is now evident that short-chain fatty acids (SCFAs), mainly acetate, butyrate and propionate, produced by anaerobic bacterial fermentation of the dietary fiber in the intestine, have a key role in the communication between the gastrointestinal tract and nervous system and are critically important for the preservation of the BBB integrity under different pathological conditions. The effect of SCFAs on the improvement of the compromised BBB is mainly based on the decrease in paracellular permeability via restoration of junctional complex proteins affecting their transcription, intercellular localization or proteolytic degradation. This review is focused on the revealed and putative underlying mechanisms of the direct and indirect effects of SCFAs on the improvement of the barrier function of brain endothelial cells. We consider G-protein-coupled receptor-mediated effects of SCFAs, SCFAs-stimulated acetylation of histone and non-histone proteins via inhibition of histone deacetylases, and crosstalk of these signaling pathways with transcriptional factors NF-κB and Nrf2 as mainstream mechanisms of SCFA's effect on the preservation of the BBB integrity.

Investigational Microbiological Therapy for Glioma

Glioma is the most common primary malignancy of the central nervous system (CNS), and 50% of patients present with glioblastoma (GBM), which is the most aggressive type. Currently, the most popular therapies are progressive chemotherapy and treatment with temozolomide (TMZ), but the median survival of glioma patients is still low as a result of the emergence of drug resistance, so we urgently need to find new therapies. A growing number of studies have shown that the diversity, bioactivity, and manipulability of microorganisms make microbial therapy a promising approach for cancer treatment. However, the many studies on the research progress of microorganisms and their derivatives in the development and treatment of glioma are scattered, and nobody has yet provided a comprehensive summary of them. Therefore, in this paper, we review the research progress of microorganisms and their derivatives in the development and treatment of glioma and conclude that it is possible to treat glioma by exogenous microbial therapies and targeting the gut-brain axis. In this article, we discuss the prospects and pressing issues relating to these therapies with the aim of providing new ideas for the treatment of glioma.

Biocorona modulates the inflammatory response induced by gold nanoparticles in human epidermal keratinocytes

The functional activities of gold nanoparticles (AuNPs) on biological systems depend on their physical-chemical properties and their surface functionalizations. Within a biological environment and depending on their surface characteristics, NPs can adsorb biomolecules (mostly proteins) present in the microenvironment, thereby forming a dynamic biomolecular corona on the surface. The presence of this biocorona changes the physical-chemical and functional properties of the NPs and how it interacts with cells. Here, we show that primary human epidermal keratinocytes (HEK) exposed in culture to branched polyethyleneimine (BPEI)-AuNPs, but not to lipoic acid (LA)-AuNPs, show potent particle uptake, decreased viability and enhanced production of inflammatory factors, while the presence of a human plasma-derived biocorona decreased NPs uptake and rescued cells from BPEI-AuNP-induced cell death. The mechanistic study revealed that the intracellular oxidative level greatly increased after the BPEI-AuNPs treatment, and the transcriptomic analysis showed that the dominant modulated pathways were related to oxidative stress and an antioxidant response. The stress level measured by flow cytometry also showed a significant decrease in the presence of a biocorona. Further anaylsis discovered that nuclear factor erythroid-2 related factor (Nrf2), a major regulator of anti-oxidant and anti-inflammatory gene, as the key factor related to the AuNPs induced oxidative stress and inflammation. This study provides futher understanding into the mechanisms on how NPs-induced cellular stress and reveals the protective effects of a biocorona on inflammatory responses in HEK at the molecular level, which provides important insights into the biological responses of AuNPs and their biocorona.

Microbial Metabolites Orchestrate a Distinct Multi-Tiered Regulatory Network in the Intestinal Epithelium That Directs P-Glycoprotein Expression

P-glycoprotein (P-gp) is a key component of the intestinal epithelium playing a pivotal role in removal of toxins and efflux of endocannabinoids to prevent excessive inflammation and sustain homeostasis. Recent studies revealed butyrate and secondary bile acids, produced by the intestinal microbiome, potentiate the induction of functional P-gp expression. We now aim to determine the molecular mechanism by which this functional microbiome output regulates P-gp. RNA sequencing of intestinal epithelial cells responding to butyrate and secondary bile acids in combination discovered a unique transcriptional program involving multiple pathways that converge on P-gp induction. Using shRNA knockdown and CRISPR/Cas9 knockout cell lines, as well as mouse models, we confirmed the RNA sequencing findings and discovered a role for intestinal HNF4α in P-gp regulation. These findings shed light on a sophisticated signaling network directed by intestinal microbial metabolites that orchestrate P-gp expression and highlight unappreciated connections between multiple pathways linked to colonic health. IMPORTANCE Preventing aberrant inflammation is essential to maintaining homeostasis in the mammalian intestine. Although P-glycoprotein (P-gp) expression in the intestine is critical for protecting the intestinal epithelium from toxins and damage due to neutrophil infiltration, its regulation in the intestine is poorly understood. Findings presented in our current study have now uncovered a sophisticated and heretofore unappreciated intracellular signaling network or "reactome" directed by intestinal microbial metabolites that orchestrate regulation of P-gp. Not only do we confirm the role of histone deacetylases (HDAC) inhibition and nuclear receptor activation in P-gp induction by butyrate and bile acids, but we also discovered new signaling pathways and transcription factors that are uniquely activated in response to the combination of microbial metabolites. Such findings shed new light into a multi-tiered network that maintains P-gp expression in the intestine in the context of the fluctuating commensal microbiome, to sustain a homeostatic tone in the absence of infection or insult.

Mechanisms of Short-Chain Fatty Acids Derived from Gut Microbiota in Alzheimer's Disease

Short-chain fatty acids (SCFAs) are important metabolites derived from the gut microbiota through fermentation of dietary fiber. SCFAs participate a number of physiological and pathological processes in the human body, such as host metabolism, immune regulation, appetite regulation. Recent studies on gut-brain interaction have shown that SCFAs are important mediators of gut-brain interactions and are involved in the occurrence and development of many neurodegenerative diseases, including Alzheimer's disease. This review summarizes the current research on the potential roles and mechanisms of SCFAs in AD. First, we introduce the metabolic distribution, specific receptors and signaling pathways of SCFAs in human body. The concentration levels of SCFAs in AD patient/animal models are then summarized. In addition, we illustrate the effects and mechanisms of SCFAs on the cognitive level, pathological features (Aβ and tau) and neuroinflammation in AD. Finally, we analyze the translational value of SCFAs as potential therapeutic targets for the treatment of AD.

Redox signaling at the crossroads of human health and disease

Redox biology is at the core of life sciences, accompanied by the close correlation of redox processes with biological activities. Redox homeostasis is a prerequisite for human health, in which the physiological levels of nonradical reactive oxygen species (ROS) function as the primary second messengers to modulate physiological redox signaling by orchestrating multiple redox sensors. However, excessive ROS accumulation, termed oxidative stress (OS), leads to biomolecule damage and subsequent occurrence of various diseases such as type 2 diabetes, atherosclerosis, and cancer. Herein, starting with the evolution of redox biology, we reveal the roles of ROS as multifaceted physiological modulators to mediate redox signaling and sustain redox homeostasis. In addition, we also emphasize the detailed OS mechanisms involved in the initiation and development of several important diseases. ROS as a double‐edged sword in disease progression suggest two different therapeutic strategies to treat redox‐relevant diseases, in which targeting ROS sources and redox‐related effectors to manipulate redox homeostasis will largely promote precision medicine. Therefore, a comprehensive understanding of the redox signaling networks under physiological and pathological conditions will facilitate the development of redox medicine and benefit patients with redox‐relevant diseases.

Low Serum Superoxide Dismutase Is Associated With a High Risk of Cognitive Impairment After Mild Acute Ischemic Stroke

Background

Post-stroke cognitive impairment (PSCI) is a common complication after stroke, but effective therapy is limited. Identifying potential risk factors for effective intervention is warranted. We investigated whether serum superoxide dismutase (SOD) levels were related to cognitive impairment after mild acute ischemic stroke (AIS) by using a prospective cohort design.

Methods

A total of 187 patients diagnosed with mild AIS (National Institutes of Health Stroke Scale ≤ 8) were recruited. Serum SOD, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and interleukin-6 (IL-6) levels were measured, and cognitive assessments (Mini-Mental State Examination, MMSE; Montreal Cognitive Assessment, MoCA) were performed in the early phase (within 2 weeks). These indexes and assessments were repeated at 3 months after onset. MoCA < 22 was defined as early cognitive impairment (CI-E) within 2 weeks and late cognitive impairment (CI-L) at 3 months after stroke.

Results

In a survey, 105 of 187 (56.1%) patients were identified as CI-E after mild AIS. Lower serum SOD associated with higher inflammatory biomarkers (ESR, CRP, and IL-6) and worse cognitive scores was observed in CI-E patients. In a survey, 39 of 103 (37.9%) stroke patients who completed the 3-month follow-up were identified as CI-L. Serum SOD was consistently lower in CI-L patients at baseline and 3 months and positively associated with cognitive scores. In adjusted analyses, low serum SOD at baseline was independently associated with high risks of CI-E and CI-L, with odds ratios (ORs) of 0.64 and 0.33 per standard deviation increase in serum SOD, respectively. Multiple-adjusted spline regression models showed linear associations between serum SOD and CI-E (P = 0.044 for linearity) and CI-L (P = 0.006 for linearity). Moreover, 35.2% (19/54) of CI-E patients cognitively recovered during the 3-month follow-up. In multivariable analysis, SOD was identified as a protective factor for cognitive recovery after stroke (OR 1.04, 95% CI: 1.01-1.08, P = 0.024).

Conclusion

We demonstrate that low serum SOD is associated with a high risk of cognitive impairment after mild AIS, indicating SOD may be a potential modifiable factor for PSCI.

Intake of flavonoids from Astragalus membranaceus ameliorated brain impairment in diabetic mice via modulating brain-gut axis

Background

Brain impairment is one of a major complication of diabetes. Dietary flavonoids have been recommended to prevent brain damage. Astragalus membranaceus is a herbal medicine commonly used to relieve the complications of diabetes. Flavonoids is one of the major ingredients of Astragalus membranaceus, but its function and mechanism on diabetic encepholopathy is still unknown.

Methods

Type 2 diabetes mellitus (T2DM) model was induced by high fat diet and STZ in C57BL/6J mice, and BEnd.3 and HT22 cell lines were applied in the in vitro study. Quality of flavonoids was evaluated by LC–MS/MS. Differential expressed proteins in the hippocampus were evaluated by proteomics; influence of the flavonoids on composition of gut microbiota was analyzed by metagenomics. Mechanism of the flavonoids on diabetic encepholopathy was analyzed by Q-PCR, Western Blot, and multi-immunological methods et al.

Results

We found that flavonoids from Astragalus membranaceus (TFA) significantly ameliorated brain damage by modulating gut-microbiota-brain axis: TFA oral administration decreased fasting blood glucose and food intake, repaired blood brain barrier, protected hippocampus synaptic function; improved hippocampus mitochondrial biosynthesis and energy metabolism; and enriched the intestinal microbiome in high fat diet/STZ-induced diabetic mice. In the in vitro study, we found TFA increased viability of HT22 cells and preserved gut barrier integrity in CaCO₂ monocellular layer, and PGC1α/AMPK pathway participated in this process.

Conclusion

Our findings demonstrated that flavonoids from Astragalus membranaceus ameliorated brain impairment, and its modulation on gut-brain axis plays a pivotal role. Our present study provided an alternative solution on preventing and treating diabetic cognition impairment.

Short-chain fatty acids as modulators of redox signaling in health and disease

Short-chain fatty acids (SCFAs), produced by colonic bacteria and obtained from the diet, have been linked to beneficial effects on human health associated with their metabolic and signaling properties. Their physiological functions are related to their aliphatic tail length and dependent on the activation of specific membrane receptors. In this review, we focus on the mechanisms underlying SCFAs mediated protection against oxidative and mitochondrial stress and their role in regulating metabolic pathways in specific tissues. We critically evaluate the evidence for their cytoprotective roles in suppressing inflammation and carcinogenesis and the consequences of aging. The ability of these natural compounds to induce signaling pathways, involving nuclear erythroid 2-related factor 2 (Nrf2), contributes to the maintenance of redox homeostasis under physiological conditions. SCFAs may thus serve as nutritional and therapeutic agents in healthy aging and in vascular and other diseases such as diabetes, neuropathologies and cancer.

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SCFAs are a link between the microbiota, redox signaling and host metabolism.

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SCFAs modulate Nrf2 redox signaling through specific free fatty acid receptors.

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Butyrate induces epigenetic regulation and/or Nrf2 nuclear translocation.

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Butyrate and propionate protect the blood-brain barrier by facilitating docosahexaenoic acid transport.

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Regulation of redox homeostasis by SCFAs supports their potential as therapeutic nutrients in health and disease.

Host and microbiota metabolic signals in aging and longevity

Aging is an inevitable biochemical process that adversely affects personal health and poses ever-increasing challenges to society. Recent research has revealed the crucial role of metabolism in regulating aging and longevity. During diverse metabolic processes, the host organism and their symbiotic partners-the microbiota-produce thousands of chemical products (metabolites). Emerging studies have uncovered specific metabolites that act as signaling molecules to actively regulate longevity. Here we review the latest progress in understanding the molecular mechanisms by which metabolites from the host and/or microbiota promote longevity. We also highlight state-of-the-art technologies for discovering, profiling and imaging aging- and longevity-regulating metabolites and for deciphering the molecular basis of their actions. The broad application of these technologies in aging research, together with future advances, will foster the systematic discovery of aging- and longevity-regulating metabolites and their signaling pathways. These metabolite signals should provide promising targets for developing new interventions to promote longevity and healthy aging.

Butyrate Protects Pancreatic Beta Cells from Cytokine-Induced Dysfunction

Pancreatic beta cell dysfunction caused by metabolic and inflammatory stress contributes to the development of type 2 diabetes (T2D). Butyrate, produced by the gut microbiota, has shown beneficial effects on glucose metabolism in animals and humans and may directly affect beta cell function, but the mechanisms are poorly described. The aim of this study was to investigate the effect of butyrate on cytokine-induced beta cell dysfunction in vitro. Mouse islets, rat INS-1E, and human EndoC-βH1 beta cells were exposed long-term to non-cytotoxic concentrations of cytokines and/or butyrate to resemble the slow onset of inflammation in T2D. Beta cell function was assessed by glucose-stimulated insulin secretion (GSIS), gene expression by qPCR and RNA-sequencing, and proliferation by incorporation of EdU into newly synthesized DNA. Butyrate protected beta cells from cytokine-induced impairment of GSIS and insulin content in the three beta cell models. Beta cell proliferation was reduced by both cytokines and butyrate. Expressions of the beta cell specific genes Ins, MafA, and Ucn3 reduced by the cytokine IL-1β were not affected by butyrate. In contrast, butyrate upregulated the expression of secretion/transport-related genes and downregulated inflammatory genes induced by IL-1β in mouse islets. In summary, butyrate prevents pro-inflammatory cytokine-induced beta cell dysfunction.

Multiple roles of short-chain fatty acids in Alzheimer disease

Alzheimer disease (AD) is the most common form of neurodegenerative disease in older adults and has a complicated etiology. Recently, the roles of short-chain fatty acids (SCFAs), the main metabolites generated by fermentation of dietary fiber by gut microbiota, in the pathogenesis of AD have attracted considerable interest. This study analyzed the multiple roles of SCFAs in AD pathogenesis from five aspects, including: 1) epigenetic regulation; 2) modulation of neuroinflammation; 3) maintenance of the blood-brain barrier (BBB); 4) regulation of brain metabolism; and 5) interference in amyloid protein formation. According to the currently available evidence, SCFAs, particularly butyrate, cause important biological effects that interfere with the development of AD. However, the effect of other SCFAs, such as propionate, on AD might be either beneficial or harmful to different pathways, indicating that the role of SCFAs in the pathogenesis of AD is rather complicated and warrants further investigations.

The cholesterol esterification inhibitor avasimibe suppresses tumour proliferation and metastasis via the E2F-1 signalling pathway in prostate cancer

Background

New effective drugs for prostate cancer (PCa) treatment are urgently needed. Avasimibe was recently identified as a promising drug for anticancer therapies. The main purpose of this study was to explore the effects and the underlying mechanisms of avasimibe in prostate cancer.

Methods

In this study, MTT and clonogenic survival assays were performed to detect cell proliferation after avasimibe treatment. The effect of avasimibe on cell migration was measured by wound healing and transwell migration assays. Cell cycle distribution and apoptosis were detected by flow cytometry. Immunofluorescence staining and western blot analysis were used to detect the expression of cell cycle-related proteins and epithelial-mesenchymal transition (EMT)-related proteins. In vivo, the antitumour effects of avasimibe were evaluated using a xenograft model and pulmonary metastasis model.

Results

The study found that avasimibe suppresses tumour growth and triggers G1 phase arrest. Moreover, the expression of the cell cycle-related proteins CDK2/4/6, Cyclin D1 and Cyclin A1 + A2 was significantly increased and p21 expression was decreased after avasimibe treatment. The migration of PCa cells was attenuated after treatment with avasimibe, followed by the downregulation of the expression of the EMT-related proteins N-cadherin, β-catenin, vimentin, Snail and MMP9 and upregulation of E-cadherin expression. Moreover, E2F-1 was elevated after treatment with avasimibe. After knockdown of E2F-1 expression, the inhibition of cell proliferation and migration caused by avasimibe was significantly recovered. The results of the xenograft model showed that avasimibe suppressed tumour growth in vivo. Immunofluorescence staining revealed lower levels of Ki67 and higher levels of E2F-1 in tumour tissues of the avasimibe group than those of the control group. A pulmonary metastasis model also confirmed the inhibition of PCa metastasis by avasimibe. The number of lung metastatic foci in the avasimibe group was significantly decreased compared with that in the control group.

Conclusions

Our results suggest that avasimibe can suppress tumour proliferation and metastasis via the E2F-1 signalling pathway. These findings demonstrate the potential of avasimibe as a new effective drug for PCa treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02175-5.

Neuroprotective Effects of Sodium Butyrate through Suppressing Neuroinflammation and Modulating Antioxidant Enzymes

The discovery of effective therapeutic agents against neurodegenerative diseases (NDDs) remains challenging. Neurotoxicity, inflammations, and oxidative stress are associating factors of NDDs. Sodium butyrate (NaB) is a short-chain fatty acid found in diet and produced in the gut that reportedly protects cancer, inflammation, obesity and so on. Previously, SH-SY5Y cells were studied as in vitro models of cerebral diseases. We have investigated the neuroprotective effects of NaB in SH-SY5Y cells stimulated with TNF-α. The expression of inflammatory mediators, including iNOS, COX-2, and mitogen-activated protein kinases (MAPK) and the apoptotic regulators, including P-53, Bcl-2 associated X (BAX) Protein, and caspase-3 were analyzed by western blot analysis. The anti-apoptotic gene Bcl-2 and the pro-apoptotic gene BAX translocation were also investigated. Our results showed that NaB attenuated cell death and inhibited the NO production and decreased the expression of iNOS and COX-2 in TNF-α-stimulated SH-SY5Y cells. NaB notably ameliorated apoptotic regulatory proteins p-53, Caspase-3 and caspase-1 level, and reversed phosphorylation of extracellular signal-regulated kinases and p-38 proteins. NaB ameliorated Glucocorticoid receptor and NLRP3 inflammasome expressions. NaB also suppressed the BAX nuclear translocation and modulated Nrf-2, HO-1 and MnSOD expression in neuroblastoma cells. In addition, NaB substantially reversed the reactive oxygen species in H₂O₂ induced SH-SY5Y cells. Altogether, our results suggest that sodium butyrate has potential therapeutic effects against NDDs.

Epigenetic regulation in Alzheimer's disease: is it a potential therapeutic target?

Introduction: Alzheimer's disease (AD) is the most common neurodegenerative disorder and the primary form of dementia in the elderly. Changes in DNA methylation and post-translational modifications of histone tails are increasingly observed in AD tissues, and likely contribute to disease onset and progression. The reversibility of these epigenetic marks offers the potential for therapeutic interventions.Areas covered: After a concise and updated overview of DNA methylation and post-translational modifications of histone tails in AD tissues, this review provides an overview of the animal and cell culture studies investigating the potential of targeting these modifications to attenuate AD-like features. PubMed was searched for relevant literature between 2003 and 2021.Expert opinion: Methyl donor compounds and drugs acting on histone tail modifications attenuated the AD-like features and improved cognition in several transgenic AD mice; however, there are concerns about safety and tolerability for long-term treatment in humans. The challenges will be to take advantage of recent epigenome-wide investigations to identify the principal targets for future interventions, and to design novel, selective and safer agents. Natural compounds exerting epigenetic properties could represent a promising opportunity to delay disease onset in middle-aged individuals at increased AD risk.

Anti-Interleukin-16 Neutralizing Antibody Treatment Alleviates Sepsis-Induced Cardiac Injury and Dysfunction via the Nuclear Factor Erythroid-2 Related Factor 2 Pathway in Mice

Several interleukin (IL) members have been reported to participate in sepsis. In this study, the effects of IL-16 on sepsis-induced cardiac injury and dysfunction were examined, and the related mechanisms were detected. IL-16 expression in septic mice was first measured, and the results showed that both cardiac and serum IL-16 expression levels were increased in mice with sepsis induced by LPS or cecal ligation and puncture (CLP) compared with control mice. Then, IL-16 was neutralized, and the effects on lipopolysaccharide- (LPS-) induced cardiac injury were detected. The results showed that an anti-IL-16 neutralizing antibody (nAb) significantly reduced mortality and increased serum lactate dehydrogenase (LDH), creatine kinase myocardial bound (CK-MB), and cardiac troponin T (cTnT) levels while improving cardiac function in mice with LPS-induced sepsis. Neutralization of IL-16 also increased the activation of antioxidant pathways and the expression of antioxidant factors in septic mice while decreasing the activation of prooxidant pathways and the expression of prooxidants. Treatment with the anti-IL-16 nAb increased mitochondrial apoptosis-inducing factor (AIF) expression, decreased nuclear AIF and cleaved poly-ADP-ribose polymerase (PARP) expression, and decreased TUNEL-positive cell percentages in LPS-treated mice. Additionally, treatment with CPUY192018, the nuclear factor erythroid-2 related factor 2 (Nrf2) pathway, significantly increased mortality and reversed the above effects in mice treated with LPS and the anti-IL-16 nAb. Our results showed that the anti-IL-16 nAb regulates oxidative stress through the Nrf2 pathway and participates in the regulation of cardiac injury in septic mice. Neutralization of IL-16 may be a beneficial strategy for the prevention of cardiac injury and dysfunction in sepsis patients.

Diet, Microbiota and Brain Health: Unraveling the Network Intersecting Metabolism and Neurodegeneration

Increasing evidence gives support for the idea that extra-neuronal factors may affect brain physiology and its predisposition to neurodegenerative diseases. Epidemiological and experimental studies show that nutrition and metabolic disorders such as obesity and type 2 diabetes increase the risk of Alzheimer's and Parkinson's diseases after midlife, while the relationship with amyotrophic lateral sclerosis is uncertain, but suggests a protective effect of features of metabolic syndrome. The microbiota has recently emerged as a novel factor engaging strong interactions with neurons and glia, deeply affecting their function and behavior in these diseases. In particular, recent evidence suggested that gut microbes are involved in the seeding of prion-like proteins and their spreading to the central nervous system. Here, we present a comprehensive review of the impact of metabolism, diet and microbiota in neurodegeneration, by affecting simultaneously several aspects of health regarding energy metabolism, immune system and neuronal function. Advancing technologies may allow researchers in the future to improve investigations in these fields, allowing the buildup of population-based preventive interventions and development of targeted therapeutics to halt progressive neurologic disability.

Ellagic Acid-Derived Urolithins as Modulators of Oxidative Stress

Oxidative stress is a state of excess of prooxidative species relative to the antioxidant defenses (enzymatic and nonenzymatic) in a living organism. The consequence of this imbalance is damage of the major cellular macromolecules (carbohydrates, lipids, proteins, and DNA), which further leads to a gradual loss of tissue and organ function. It has been shown that oxidative stress plays an important role in the pathogenesis of many chronic diseases (cardiovascular, metabolic, and neurodegenerative diseases and cancer) and in the process of aging. Thus, many strategies to combat oxidative stress have been proposed and tested. In this context, food rich in antioxidants has received great attention. Pomegranate, berries, and walnuts have been recognized as “superfood” particularly for their cardioprotective effects. The common characteristic of these foods is the high content of ellagitannins. Since tannins are not bioavailable, they have been neglected in nutrition science and even considered antinutrients for a long time. However, this view has changed dramatically once it was recognized that ellagic acid, released from ellagitannins in the gastrointestinal system, is further metabolized by colonic microbiota to bioavailable compounds—known as urolithins. Thus, urolithins (3,4-benzocoumarin derivatives) have emerged as novel natural bioactive compounds and are now the focus of extensive investigations. So far, urolithins were shown to be powerful modulators of oxidative stress and agents with potential anti-inflammatory, antiproliferative, and antiaging properties. Furthermore, a few synthetic derivatives of urolithins were recognized as lead compounds for new drug development. Available data on urolithin synthesis, physicochemical and pharmacokinetic characteristics, biological activity, and safety will be presented in this review.