Phloretin suppresses neuroinflammation by autophagy-mediated Nrf2 activation in macrophages

Promoting remyelination in central nervous system diseases: Potentials and prospects of natural products and herbal medicine

Myelin damage is frequently associated with central nervous system (CNS) diseases and is a critical factor influencing neurological function and disease prognosis. Nevertheless, the majority of current treatments for the CNS concentrate on gray matter injury and repair strategies, while clinical interventions specifically targeting myelin repair remain unavailable. In recent years, natural products and herbal medicine have achieved considerable progress in the domain of myelin repair, given their remarkable curative effect and low toxic side effects, demonstrating significant therapeutic potential. In this review, we present a rather comprehensive account of the mechanisms underlying myelin formation, injury, and repair, with a particular emphasis on the interactions between oligodendrocytes and other glial cells. Furthermore, we summarize the natural products and herbal medicine currently employed in remyelination along with their mechanisms of action, highlighting the potential and challenges of certain natural compounds to enhance myelin repair. This review aims to facilitate the expedited development of innovative therapeutics derived from natural products and herbal medicine and furnish novel insights into myelin repair in the CNS.

The potential therapeutic strategy in combating neurodegenerative diseases: Focusing on natural products

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), Huntington disease (HD), and Multiple sclerosis (MS), pose a significant global health challenge due to their intricate pathology and limited therapeutic interventions. Natural products represent invaluable reservoirs for combating these neurodegenerative diseases by targeting key pathological hallmarks such as protein aggregation, synaptic dysfunction, aberrant proteostasis, cytoskeletal abnormalities, altered energy homeostasis, inflammation, and neuronal cell death. This review provides an in-depth analysis of the mechanisms and therapeutic targets of natural products for their neuroprotective effects. Furthermore, it elucidates the current progress of clinical trials investigating the potential of natural products in delaying neurodegeneration. The objective of this review is to enhance the comprehension of natural products in the prevention and treatment of neurodegenerative diseases, offering new insights and potential avenues for future pharmaceutical research.

Research progress on the role and inhibitors of Keap1 signaling pathway in inflammation

Inflammation is a protective mechanism against endogenous and exogenous pathogens. It is a typical feature of numerous chronic diseases and their complications. Keap1 is an essential target in oxidative stress and inflammatory diseases. Among them, the Keap1-Nrf2-ARE pathway (including Keap1-Nrf2-HO-1) is the most significant pathway of Keap1 targets, which participates in the control of inflammation in multiple organs (including renal inflammation, lung inflammation, liver inflammation, neuroinflammation, etc.). Identifying new Keap1 inhibitors is crucial for new drug discovery. However, most drugs have specificity issues as they covalently bind to cysteine residues of Keap1, causing off-target effects. Therefore, direct inhibition of Keap1-Nrf2 PPIs is a new research idea. Through non-electrophilic and non-covalent binding, its inhibitors have better specificity and ability to activate Nrf2, and targeting therapy against Keap1-Nrf2 PPIs has become a new method for drug development in chronic diseases. This review summarizes the members and downstream genes of the Keap1-related pathway and their roles in inflammatory disease models. In addition, we summarize all the research progress of anti-inflammatory drugs targeting Keap1 from 2010 to 2024, mainly describing their biological functions, molecular mechanisms of action, and therapeutic roles in inflammatory diseases.

A Systematic Review: Quercetin-Secondary Metabolite of the Flavonol Class, with Multiple Health Benefits and Low Bioavailability

The main goal of this systematic review on the flavonol class secondary metabolite quercetin is to evaluate and summarize the existing research on quercetin's potential health benefits, therapeutic properties, and effectiveness in disease prevention and treatment. In addition to evaluating quercetin's potential for drug development with fewer side effects and lower toxicity, this type of review attempts to collect scientific evidence addressing quercetin's roles as an antioxidant, anti-inflammatory, antibacterial, and anticancer agent. In the first part, we analyze various flavonoid compounds, focusing on their chemical structure, classification, and natural sources. We highlight their most recent biological activities as reported in the literature. Among these compounds, we pay special attention to quercetin, detailing its chemical structure, physicochemical properties, and process of biosynthesis in plants. We also present natural sources of quercetin and emphasize its health benefits, such as its antioxidant and anti-inflammatory effects. Additionally, we discuss methods to enhance its bioavailability, analyzing the latest and most effective delivery systems based on quercetin.

Phloretin attenuates inflammation induced by subarachnoid hemorrhage through regulation of the TLR2/MyD88/NF-kB pathway

Subarachnoid hemorrhage (SAH), a stroke subtype associated with high mortality, is closely linked to neuroinflammation. Phloretin, a naturally occurring flavonoid abundant in fruits, possesses anti-inflammatory properties. However, its specific role in SAH remains unclear. Therefore, we aimed to investigate the potential role of phloretin in SAH. We established in vitro and in vivo SAH models to assess the effects of phloretin. Subsequently, utilizing SAH-related public datasets from the GEO database, we identified key genes associated with SAH and investigated the potential mechanism of action of phloretin. Our findings reveal that phloretin significantly improves prognostic outcomes and mitigates inflammation in SAH mice. Moreover, our results suggest that phloretin mitigates neuroinflammation by inhibiting the TLR2/MYD88/NF-κB pathway.

The role of Nrf2 in immune cells and inflammatory autoimmune diseases: a comprehensive review

INTRODUCTION

Nrf2 regulates mild stress, chronic inflammation, and metabolic changes by regulating different immune cells via downstream signaling. Collection of information about the role of Nrf2 in inflammatory autoimmune diseases will better understand the therapeutic potential of targeting Nrf2 in these diseases.

AREAS COVERED

In this review, we comprehensively discussed biological function of Nrf2 in different immune cells, including Nrf2 preventing oxidative tissue injury, affecting apoptosis of immune cells and inflammatory cytokine production. Moreover, we discussed the role of Nrf2 in the development of inflammatory autoimmune diseases.

EXPERT OPINION

Nrf2 binds to downstream signaling molecules and then provides durable protection against different cellular and organ stress. It has emerged as an important target for inflammatory autoimmune diseases. Development of Nrf2 modulator drugs needs to consider factors such as target specificity, short/long term safety, disease indication identification, and the extent of variation in Nrf2 activity. We carefully discussed the dual role of Nrf2 in some diseases, which helps to better target Nrf2 in the future.

AMP-activated protein kinase as a mediator of mitochondrial dysfunction of multiple sclerosis in animal models: A systematic review

Multiple sclerosis (MS) is a chronic central nervous system (CNS) disorder characterized by demyelination, neuronal damage, and oligodendrocyte depletion. Reliable biomarkers are essential for early diagnosis and disease management. Emerging research highlights the role of mitochondrial dysfunction and oxidative stress in CNS disorders, including MS, in which mitochondria are central to the degenerative process. Adenosine monophosphate-activated protein kinase (AMPK) regulates the mitochondrial energy balance and initiates responses in neurodegenerative conditions. This systematic review, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, aimed to comprehensively assess the literature on AMPK pathways, mitochondrial dysfunction, and in vivo studies using MS animal models. The search strategy involved the use of AMPK syntaxes, MS syntaxes, and animal model syntaxes. The PubMed, Scopus, Web of Science, and Google Scholar databases were systematically searched on August 26, 2023 without publication year restrictions. The review identified and analyzed relevant papers to provide a comprehensive overview of the current state of related research. Eight studies utilizing various interventions and methodological approaches were included. Risk of bias assessment revealed some areas of low risk but lacked explicit reporting in others. These studies collectively revealed a complex relationship between AMPK, mitochondrial dysfunction, and MS pathogenesis, with both cuprizone and experimental autoimmune encephalomyelitis models demonstrating associations between AMPK and mitochondrial disorders, including oxidative stress and impaired expression of mitochondrial genes. These studies illuminate the multifaceted role of AMPK in MS animal models, involving energy metabolism, inflammatory processes, oxidative stress, and gene regulation leading to mitochondrial dysfunction. However, unanswered questions about its mechanisms and clinical applications underscore the need for further research to fully harness its potential in addressing MS-related mitochondrial dysfunction.

Phloretin inhibits transmissible gastroenteritis virus proliferation via multiple mechanisms

Transmissible gastroenteritis virus (TGEV), an enteropathogenic coronavirus, has caused huge economic losses to the pig industry, with 100% mortality in piglets aged 2 weeks and intestinal injury in pigs of other ages. However, there is still a shortage of safe and effective anti-TGEV drugs in clinics. In this study, phloretin, a naturally occurring dihydrochalcone glycoside, was identified as a potent antagonist of TGEV. Specifically, we found phloretin effectively inhibited TGEV proliferation in PK-15 cells, dose-dependently reducing the expression of TGEV N protein, mRNA, and virus titer. The anti-TGEV activity of phloretin was furthermore refined to target the internalization and replication stages. Moreover, we also found that phloretin could decrease the expression levels of proinflammatory cytokines induced by TGEV infection. In addition, we expanded the potential key targets associated with the anti-TGEV effect of phloretin to AR, CDK2, INS, ESR1, ESR2, EGFR, PGR, PPARG, PRKACA, and MAPK14 with the help of network pharmacology and molecular docking techniques. Furthermore, resistant viruses have been selected by culturing TGEV with increasing concentrations of phloretin. Resistance mutations were reproducibly mapped to the residue (S242) of main protease (Mpro). Molecular docking analysis showed that the mutation (S242F) significantly disrupted phloretin binding to Mpro, suggesting Mpro might be a potent target of phloretin. In summary, our findings indicate that phloretin is a promising drug candidate for combating TGEV, which may be helpful for developing pharmacotherapies for TGEV and other coronavirus infections.

Oxidative stress involvement in the molecular pathogenesis and progression of multiple sclerosis: a literature review

Multiple sclerosis (MS) is an autoimmune debilitating disease of the central nervous system caused by a mosaic of interactions between genetic predisposition and environmental factors. The pathological hallmarks of MS are chronic inflammation, demyelination, and neurodegeneration. Oxidative stress, a state of imbalance between the production of reactive species and antioxidant defense mechanisms, is considered one of the key contributors in the pathophysiology of MS. This review is a comprehensive overview of the cellular and molecular mechanisms by which oxidant species contribute to the initiation and progression of MS including mitochondrial dysfunction, disruption of various signaling pathways, and autoimmune response activation. The detrimental effects of oxidative stress on neurons, oligodendrocytes, and astrocytes, as well as the role of oxidants in promoting and perpetuating inflammation, demyelination, and axonal damage, are discussed. Finally, this review also points out the therapeutic potential of various synthetic antioxidants that must be evaluated in clinical trials in patients with MS.

Computational identification of natural senotherapeutic compounds that mimic dasatinib based on gene expression data

The major risk factor for chronic disease is chronological age, and age-related chronic diseases account for the majority of deaths worldwide. Targeting senescent cells that accumulate in disease-related tissues presents a strategy to reduce disease burden and to increase healthspan. The senolytic combination of the tyrosine-kinase inhibitor dasatinib and the flavonol quercetin is frequently used in clinical trials aiming to eliminate senescent cells. Here, our goal was to computationally identify natural senotherapeutic repurposing candidates that may substitute dasatinib based on their similarity in gene expression effects. The natural senolytic piperlongumine (a compound found in long pepper), and the natural senomorphics parthenolide, phloretin and curcumin (found in various edible plants) were identified as potential substitutes of dasatinib. The gene expression changes underlying the repositioning highlight apoptosis-related genes and pathways. The four compounds, and in particular the top-runner piperlongumine, may be combined with quercetin to obtain natural formulas emulating the dasatinib + quercetin formula.

Polyphenols: immunonutrients tipping the balance of immunometabolism in chronic diseases

Mounting evidence progressively appreciates the vital interplay between immunity and metabolism in a wide array of immunometabolic chronic disorders, both autoimmune and non-autoimmune mediated. The immune system regulates the functioning of cellular metabolism within organs like the brain, pancreas and/or adipose tissue by sensing and adapting to fluctuations in the microenvironment's nutrients, thereby reshaping metabolic pathways that greatly impact a pro- or anti-inflammatory immunophenotype. While it is agreed that the immune system relies on an adequate nutritional status to function properly, we are only just starting to understand how the supply of single or combined nutrients, all of them termed immunonutrients, can steer immune cells towards a less inflamed, tolerogenic immunophenotype. Polyphenols, a class of secondary metabolites abundant in Mediterranean foods, are pharmacologically active natural products with outstanding immunomodulatory actions. Upon binding to a range of receptors highly expressed in immune cells (e.g. AhR, RAR, RLR), they act in immunometabolic pathways through a mitochondria-centered multi-modal approach. First, polyphenols activate nutrient sensing via stress-response pathways, essential for immune responses. Second, they regulate mammalian target of rapamycin (mTOR)/AMP-activated protein kinase (AMPK) balance in immune cells and are well-tolerated caloric restriction mimetics. Third, polyphenols interfere with the assembly of NLR family pyrin domain containing 3 (NLRP3) in endoplasmic reticulum-mitochondria contact sites, inhibiting its activation while improving mitochondrial biogenesis and autophagosome-lysosome fusion. Finally, polyphenols impact chromatin remodeling and coordinates both epigenetic and metabolic reprogramming. This work moves beyond the well-documented antioxidant properties of polyphenols, offering new insights into the multifaceted nature of these compounds. It proposes a mechanistical appraisal on the regulatory pathways through which polyphenols modulate the immune response, thereby alleviating chronic low-grade inflammation. Furthermore, it draws parallels between pharmacological interventions and polyphenol-based immunonutrition in their modes of immunomodulation across a wide spectrum of socioeconomically impactful immunometabolic diseases such as Multiple Sclerosis, Diabetes (type 1 and 2) or even Alzheimer's disease. Lastly, it discusses the existing challenges that thwart the translation of polyphenols-based immunonutritional interventions into long-term clinical studies. Overcoming these limitations will undoubtedly pave the way for improving precision nutrition protocols and provide personalized guidance on tailored polyphenol-based immunonutrition plans.

Metabolomics-based investigation of the chemical composition changes in Mongolian medicinal plant Euphorbia pekinensis before and after processing with Chebulae Fructus

Euphorbia pekinensis (EP), known for its diuretic properties, is clinically utilized for treating conditions such as edema and malignant tumors. However, in its raw form, Euphorbia pekinensis is toxic, and oral administration of this crude medicine can lead to gastrointestinal stimulation, resulting in abdominal pain and diarrhea. In Mongolian medicine's ethnomedicinal system, a distinctive processing method called "Chebulae Fructus processing" is employed. Chebulae Fructus is used to mitigate the toxicity of EP and alleviate its purgative effects. Nevertheless, the detoxification mechanism associated with this processing method remains unexplored. It is hypothesized that processing with Chebulae Fructus may alter the chemical composition of EP, and the residual components of Chebulae Fructus within processed Chinese medicine might exhibit pharmacological antagonistic effects, thereby achieving the purpose of processing and reducing toxicity. To investigate this further, a combination of UPLC-QTOF-MS-based metabolomics technology and multivariate statistical analysis was employed to analyze and compare the chemical composition of raw and processed EP. Differential variables contributing to group separation were identified based on specific criteria, including VIP (Variable Importance in Projection) values of ≥ 1 in PLS-DA models, p-values < 0.05, and fold changes (FC) > 1.2 or < 0.8. The resulting differentially expressed features were then identified through database matching, literature review, or manual annotation. In total, 47 components were identified from the PEP samples in both positive and negative ionization modes, primarily belonging to flavonoids, terpenoids, organic acids, glycosides, and fatty acids. Among the raw EP group and PEP S4 group, 10 differential compounds were identified. Notably, one toxic terpene and one phenylpropanoid from EP were downregulated, while two bioactive components from Chebulae Fructus were upregulated in the processed group. The possible conversion reactions of these two processing Q-markers were also elucidated. The characteristic processing with Chebulae Fructus resulted in a change in the composition of this Mongolian medicine EP. Furthermore, this study provides a scientific foundation for optimizing the processing technology of EP and offers insights into the processing of other ethnomedicines with toxic properties.

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

Polyphenols, Autophagy and Neurodegenerative Diseases: A Review

Polyphenols are secondary metabolites from plant origin and are shown to possess a wide range of therapeutic benefits. They are also reported as regulators of autophagy, inflammation and neurodegeneration. The autophagy pathway is vital in degrading outdated organelles, proteins and other cellular wastes. The dysregulation of autophagy causes proteinopathies, mitochondrial dysfunction and neuroinflammation thereby contributing to neurodegeneration. Evidence reveals that polyphenols improve autophagy by clearing misfolded proteins in the neurons, suppress neuroinflammation and oxidative stress and also protect from neurodegeneration. This review is an attempt to summarize the mechanism of action of polyphenols in modulating autophagy and their involvement in pathways such as mTOR, AMPK, SIRT-1 and ERK. It is evident that polyphenols cause an increase in the levels of autophagic proteins such as beclin-1, microtubule-associated protein light chain (LC3 I and II), sirtuin 1 (SIRT1), etc. Although it is apparent that polyphenols regulate autophagy, the exact interaction of polyphenols with autophagy markers is not known. These data require further research and will be beneficial in supporting polyphenol supplementation as a potential alternative treatment for regulating autophagy in neurodegenerative diseases.

Phloretin-induced STAT3 inhibition suppresses pancreatic cancer growth and progression via enhancing Nrf2 activity

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a malignant pancreatic tumor charactered by a rapid progression and high lethal rate. Hyperactivation of STAT3 signaling exerts a vital effect on the growth and progression of PDAC. While dietary flavonoid phloretin has anti-inflammatory and antioxidant activities, it remains unclear whether phloretin has anti-tumor effects on PDAC.

PURPOSE

The focus of the present study is to elucidate the effects of phloretin on PDAC and investigate its underlying molecular mechanisms.

STUDY DESIGN AND METHODS

Effect of phloretin were assessed in the pancreatic cancer cells (PCCs) by colony formation assay, real-time cell analysis, flow cytometry, Immunofluorescence staining, and cell migration assay. The expressions of mRNA and protein were respectively analyzed by quantitative PCR and Western blotting. A xenograft model was used to appraise the antitumor efficacy of phloretin.

RESULTS

Phloretin treatment significantly restrained cell viability and metastasis, induced DNA injury and ROS accumulation, and triggered mitochondrial-dependent apoptosis in PCCs. Mechanistically, phloretin exhibits anti-tumor potential via inactivating STAT3 signaling and enhancing Nrf2 activity. STAT3 overexpression and Nrf2 silencing partially relieved phloretin-induced inhibition on cell growth and metastasis in PCCs. Phloretin remarkably blocked pancreatic tumor growth and metastasis in vivo.

CONCLUSIONS

Phloretin suppresses pancreatic cancer growth and progression through inhibition of STAT3 mediated by enhancing Nrf2 activity. Phloretin may serve as a promising therapeutic agent for PDAC.

Interactions between the Astrocytic Volume-Regulated Anion Channel and Aquaporin 4 in Hyposmotic Regulation of Vasopressin Neuronal Activity in the Supraoptic Nucleus

We assessed interactions between the astrocytic volume-regulated anion channel (VRAC) and aquaporin 4 (AQP4) in the supraoptic nucleus (SON). Acute SON slices and cultures of hypothalamic astrocytes prepared from rats received hyposmotic challenge (HOC) with/without VRAC or AQP4 blockers. In acute slices, HOC caused an early decrease with a late rebound in the neuronal firing rate of vasopressin neurons, which required activity of astrocytic AQP4 and VRAC. HOC also caused a persistent decrease in the excitatory postsynaptic current frequency, supported by VRAC and AQP4 activity in early HOC; late HOC required only VRAC activity. These events were associated with the dynamics of glial fibrillary acidic protein (GFAP) filaments, the late retraction of which was mediated by VRAC activity; this activity also mediated an HOC-evoked early increase in AQP4 expression and late subside in GFAP-AQP4 colocalization. AQP4 activity supported an early HOC-evoked increase in VRAC levels and its colocalization with GFAP. In cultured astrocytes, late HOC augmented VRAC currents, the activation of which depended on AQP4 pre-HOC/HOC activity. HOC caused an early increase in VRAC expression followed by a late rebound, requiring AQP4 and VRAC, or only AQP4 activity, respectively. Astrocytic swelling in early HOC depended on AQP4 activity, and so did the early extension of GFAP filaments. VRAC and AQP4 activity supported late regulatory volume decrease, the retraction of GFAP filaments, and subside in GFAP-VRAC colocalization. Taken together, astrocytic morphological plasticity relies on the coordinated activities of VRAC and AQP4, which are mutually regulated in the astrocytic mediation of HOC-evoked modulation of vasopressin neuronal activity.

Magnolol as STAT3 inhibitor for treating multiple sclerosis by restricting Th17 cells

OBJECTIVE

Multiple sclerosis (MS) is an immune disease in the central nervous system (CNS) associated with Th17 cells. Moreover, STAT3 initiates Th17 cell differentiation and IL-17A expression through facilitating RORγt in MS. Here, we reported that magnolol, isolated from Magnolia officinalis Rehd. Et Wils, was regarded as a candidate for MS treatment verified by both in vitro and in vivo studies.

METHODS

In vivo, experimental autoimmune encephalomyelitis (EAE) model in mice was employed to evaluate the alleviation of magnolol on myeloencephalitis. In vitro, FACS assay was employed to evaluate the effect of magnolol on Th17 and Treg cell differentiation and IL-17A expression; network pharmacology-based study was applied to probe the involved mechanisms; western blotting, immunocytochemistry, and luciferase reporter assay was used to further confirm the regulation of magnolol on JAK/STATs signaling pathway; surface plasmon resonance (SPR) assay and molecular docking were applied to manifest affinity with STAT3 and binding sites; overexpression of STAT3 was employed to verify whether magnolol attenuates IL-17A through STAT3 signaling pathway.

RESULTS

In vivo, magnolol alleviated loss of body weight and severity of EAE mice; magnolol improved lesions in spinal cords and attenuated CD45 infiltration, and serum cytokines levels; correspondingly, magnolol focused on inhibiting Th17 differentiation and IL-17A expression in splenocyte of EAE mice; moreover, magnolol selectively inhibited p-STAT3(Y705) and p-STAT4(Y693) of both CD4⁺ and CD8⁺ T cells in splenocyte of EAE mice. In vitro, magnolol selectively inhibited Th17 differentiation and IL-17A expression without impact on Treg cells; network pharmacology-based study revealed that magnolol perhaps diminished Th17 cell differentiation through regulating STAT family members; western blotting further confirmed that magnolol inhibited p-JAK2(Y1007) and selectively antagonized p-STAT3(Y705) and slightly decreased p-STAT4(Y693); magnolol antagonized both STAT3 nucleus location and transcription activity; magnolol had a high affinity with STAT3 and the specific binding site perhaps to be at SH2 domain; overexpression of STAT3 resulted in failed inhibition of magnolol on IL-17A.

CONCLUSION

Magnolol selectively inhibited Th17 differentiation and cytokine expression through selectively blocking of STAT3 resulting in decreased the ratio of Th17/Treg cells for treating MS, suggesting that the potential of magnolol for treating MS as novel STAT3 inhibitor.

Role of macrophage autophagy in postoperative pain and inflammation in mice

BACKGROUND

Postoperative pain and inflammation are significant complications following surgery. Strategies that aim to prevent excessive inflammation without hampering natural wound-healing are required for the management of postoperative pain and inflammation. However, the knowledge of the mechanisms and target pathways involved in these processes is lacking. Recent studies have revealed that autophagy in macrophages sequesters pro-inflammatory mediators, and it is therefore being recognized as a crucial process involved in regulating inflammation. In this study, we tested the hypothesis that autophagy in macrophages plays protective roles against postoperative pain and inflammation and investigated the underlying mechanisms.

METHODS

Postoperative pain was induced by plantar incision under isoflurane anesthesia in mice lacking macrophage autophagy (Atg5flox/flox LysMCre +) and their control littermates (Atg5flox/flox). Mechanical and thermal pain sensitivity, changes in weight distribution, spontaneous locomotor activity, tissue inflammation, and body weight were assessed at baseline and 1, 3, and 7 days after surgery. Monocyte/macrophage infiltration at the surgical site and inflammatory mediator expression levels were evaluated.

RESULTS

Atg5flox/flox LysMCre + mice compared with the control mice exhibited lower mechanical and thermal pain thresholds and surgical/non-surgical hindlimb weight-bearing ratios. The augmented neurobehavioral symptoms observed in the Atg5flox/flox LysMCre + mice were associated with more severe paw inflammation, higher pro-inflammatory mediator mRNA expression, and more monocytes/macrophages at the surgical site.

CONCLUSION

The lack of macrophage autophagy augmented postoperative pain and inflammation, which were accompanied by enhanced pro-inflammatory cytokine secretion and surgical-site monocyte/macrophage infiltration. Macrophage autophagy plays a protective role in postoperative pain and inflammation and can be a novel therapeutic target.

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.

A Review on Polyphenols in Salicornia ramosissima with Special Emphasis on Their Beneficial Effects on Brain Ischemia

There has been an increasing interest in the consumption of halophytes as a healthy food in the last few years. Salicornia ramosissima is a seasonal Mediterranean halophyte with an interesting profile of bioactive compounds, including more than 60 identified polyphenols with a broad range of biological activities. Accumulating evidence supports the role of dietary polyphenols in the prevention of cardiovascular diseases, such as stroke. Stroke is the second cause of death worldwide and it is estimated that a substantial proportion of stroke incidence and recurrence may be prevented by healthier dietary patterns. Here, we have grouped the phenolic acids and flavonoids identified in S. ramosissima and reviewed their potential protective effect on brain ischemia, which are mostly related to the reduction of oxidative stress and inflammation, the inhibition of cell death pathways and their role in the preservation of the vascular function. Despite the fact that most of these compounds have been reported to be neuroprotective through multiple mechanisms, human studies are still scarce. Given the safe profile of polyphenols identified in S. ramosissima, this halophyte plant could be considered as a source of bioactive compounds for the nutraceutical industry.

Recent Advances in Pharmaceutical Cocrystals: A Focused Review of Flavonoid Cocrystals

Cocrystallization is currently an attractive technique for tailoring the physicochemical properties of active pharmaceutical ingredients (APIs). Flavonoids are a large class of natural products with a wide range of beneficial properties, including anticancer, anti-inflammatory, antiviral and antioxidant properties, which makes them extensively studied. In order to improve the properties of flavonoids, such as solubility and bioavailability, the formation of cocrystals may be a feasible strategy. This review discusses in detail the possible hydrogen bond sites in the structure of APIs and the hydrogen bonding networks in the cocrystal structures, which will be beneficial for the targeted synthesis of flavonoid cocrystals. In addition, some successful studies that favorably alter the physicochemical properties of APIs through cocrystallization with coformers are also highlighted here. In addition to improving the solubility and bioavailability of flavonoids in most cases, flavonoid cocrystals may also alter their other properties, such as anti-inflammatory activity and photoluminescence properties.

The Molecular Pharmacology of Phloretin: Anti-Inflammatory Mechanisms of Action

The isolation of phlorizin from the bark of an apple tree in 1835 led to a flurry of research on its inhibitory effect on glucose transporters in the intestine and kidney. Using phlorizin as a prototype drug, antidiabetic agents with more selective inhibitory activity towards glucose transport at the kidney have subsequently been developed. In contrast, its hydrolysis product in the body, phloretin, which is also found in the apple plant, has weak antidiabetic properties. Phloretin, however, displays a range of pharmacological effects including antibacterial, anticancer, and cellular and organ protective properties both in vitro and in vivo. In this communication, the molecular basis of its anti-inflammatory mechanisms that attribute to its pharmacological effects is scrutinised. These include inhibiting the signalling pathways of inflammatory mediators' expression that support its suppressive effect in immune cells overactivation, obesity-induced inflammation, arthritis, endothelial, myocardial, hepatic, renal and lung injury, and inflammation in the gut, skin, and nervous system, among others.

Neuroprotective Effect of Phloretin in Rotenone-Induced Mice Model of Parkinson's Disease: Modulating mTOR-NRF2-p62 Mediated Autophagy-Oxidative Stress Crosstalk

BACKGROUND

Parkinson's disease (PD) is an age-related progressive multifactorial, neurodegenerative disease. The autophagy and Keap1-Nrf2 axis system are both implicated in the oxidative-stress response, metabolic stress, and innate immunity, and their dysregulation is associated with pathogenic processes in PD. Phloretin (PLT) is a phenolic compound reported possessing anti-inflammatory and antioxidant activities.

OBJECTIVE

To evaluate the neuroprotective potential of PLT in PD via modulating the autophagy-antioxidant axisMethods:The neuroprotective effect of PLT was evaluated in vitro using rotenone (ROT) exposed SH-SY5Y cell line and in vivo using ROT administered C57BL/6 mice. Mice were administered with PLT (50 and 100 mg/kg, p.o.) concomitantly with ROT (1 mg/kg, i.p) for 3 weeks. Locomotive activity and anxiety behaviors were assessed using rotarod and open field tests respectively. Further apoptosis (Cytochrome-C, Bax), α-Synuclein (α-SYN), tyrosine hydroxylase (TH), antioxidant proteins (nuclear factor erythroid 2-related factor 2 (NRF2), heme oxygenase-1 (HO-1) and autophagic (mTOR, Atg5,7, p62, Beclin,LC3B-I/II) protein activity were evaluated both in in vitro and in vivo.

RESULTS

PLT improved locomotive activity and anxiety-like behavior in mice. Further PLT diminished apoptotic cell death, α-SYN expression and improved the expression of TH, antioxidant, and autophagic regulating protein.

CONCLUSION

Taken together, present data deciphers that the PLT effectively improves motor and non-motor symptoms via modulating the mTOR/NRF2/p62 pathway-mediated feedback loop. Hence, PLT could emerge as a prospective disease-modifying drug for PD management.

Protective Effect of Phloretin against Hydrogen Peroxide-Induced Oxidative Damage by Enhancing Autophagic Flux in DF-1 Cells

Phloretin (PHL) is a dihydrochalcone flavonoid isolated from the peel and root bark of apples, strawberries, and other plants with antioxidative characteristic. In this study, we aimed to investigate the protective effect and the potential mechanism of PHL on hydrogen peroxide (H₂O₂)-induced oxidative damage in DF-1 cells. The results showed that PHL exhibited no cytotoxic effect on DF-1 cells at concentration below 20 μM. PHL markedly increased H₂O₂-reduced cell viability, decreased H₂O₂-induced apoptosis, as evidenced by reduced apoptosis rate, the upregulation of gene and protein level of Bcl-2, and the downregulation of gene and protein level of Bax and Cleaved caspase3. In addition, PHL reduced H₂O₂-induced reactive oxygen species (ROS) production and restored antioxidant enzymes activities as well as mitochondrial membrane potential in a dose-dependent manner. Moreover, PHL prior to H₂O₂ further increased LC3-II level, promoted p62 turnover and improved lysosomal function. Importantly, autophagy inhibitor chloroquine (CQ) reversed the protective effect of PHL, and increased H₂O₂-induced apoptosis. Furthermore, PHL inhibited the phosphorylation levels of ERK, p38, and JNK. Collectively, these results indicate that PHL could attenuate H₂O₂-induced oxidative injury and apoptosis by maintaining lysosomal function and promoting autophagic flux, and MAPKs pathway may be involved in this process. Our study provides evidence that PHL could as a new strategy to against oxidative damage in poultry industry.

Therapeutic Potential and Pharmaceutical Development of a Multitargeted Flavonoid Phloretin

Phloretin is a flavonoid of the dihydrogen chalcone class, present abundantly in apples and strawberries. The beneficial effects of phloretin are mainly associated with its potent antioxidant properties. Phloretin modulates several signaling pathways and molecular mechanisms to exhibit therapeutic benefits against various diseases including cancers, diabetes, liver injury, kidney injury, encephalomyelitis, ulcerative colitis, asthma, arthritis, and cognitive impairment. It ameliorates the complications associated with diabetes such as cardiomyopathy, hypertension, depression, memory impairment, delayed wound healing, and peripheral neuropathy. It is effective against various microbial infections including Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Escherichia coli, Candida albicans and methicillin-resistant Staphylococcus aureus. Considering the therapeutic benefits, it generated interest for the pharmaceutical development. However, poor oral bioavailability is the major drawback. Therefore, efforts have been undertaken to enhance its bioavailability by modifying physicochemical properties and molecular structure, and developing nanoformulations. In the present review, we discussed the pharmacological actions, underlying mechanisms and molecular targets of phloretin. Moreover, the review provides insights into physicochemical and pharmacokinetic characteristics, and approaches to promote the pharmaceutical development of phloretin for its therapeutic applications in the future. Although convincing experimental data are reported, human studies are not available. In order to ascertain its safety, further preclinical studies are needed to encourage its pharmaceutical and clinical development.

Potential Utility of Natural Products against Oxidative Stress in Animal Models of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune-mediated degenerative disease of the central nervous system (CNS) characterized by immune cell infiltration, demyelination and axonal injury. Oxidative stress-induced inflammatory response, especially the destructive effect of immune cell-derived free radicals on neurons and oligodendrocytes, is crucial in the onset and progression of MS. Therefore, targeting oxidative stress-related processes may be a promising preventive and therapeutic strategy for MS. Animal models, especially rodent models, can be used to explore the in vivo molecular mechanisms of MS considering their similarity to the pathological processes and clinical signs of MS in humans and the significant oxidative damage observed within their CNS. Consequently, these models have been used widely in pre-clinical studies of oxidative stress in MS. To date, many natural products have been shown to exert antioxidant effects to attenuate the CNS damage in animal models of MS. This review summarized several common rodent models of MS and their association with oxidative stress. In addition, this review provides a comprehensive and concise overview of previously reported natural antioxidant products in inhibiting the progression of MS.

Phloretin enhances autophagy by impairing AKT activation and inducing JNK-Beclin-1 pathway activation

Phloretin is a type of dihydrochalcone that is primarily found in apples and has been reported to possess various potent biological activities, such as anticancer, antioxidant and anti-inflammatory effects. Our previous study has shown that phloretin induces apoptosis in human glioblastoma. In this study, we found that phloretin induced autophagy in SH-SY5Y cells by decreasing p-AKT and p-mTOR levels in the AKT/mTOR pathway and increasing the activation of JNK, the phosphorylation of c-Jun and the expression of Beclin-1. Moreover, the upregulation of Beclin-1 was decreased by SP600125 or a siRNA against c-Jun. Furthermore, SP600125 and siRNAs against c-Jun and Beclin-1 inhibited phloretin-induced autophagy. In addition, inhibition of phloretin-induced autophagy by cotreatment with phloretin and 3-MA decreased phloretin-induced cytotoxicity to SH-SY5Y cells. In conclusion, our results suggest that the AKT/mTOR pathway and JNK-mediated Beclin-1 expression are involved in phloretin-induced autophagy. Phloretin can be used to protect neurons during phloretin treatment of glioblastoma.

The inhibition of GLUT1-induced glycolysis in macrophage by phloretin participates in the protection during acute lung injury

The increased level of glycolysis in macrophage aggravates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Glucose transporter 1 (GLUT1) serves as a ubiquitously expressed glucose transporter, which could activate inflammatory response by mediating glycolysis. Phloretin (PHL), an apple polyphenol, is also an inhibitor of GLUT1, possessing potent anti-inflammatory effects in various diseases. However, the potential role of PHL in ALI remains unclear till now. This study aims to investigate the impacts of PHL on ALI as well as its possible mechanisms. A mouse ALI model was established via intratracheal injection of LPS. LPS-induced primary macrophages were used to mimic in vitro ALI. Mice were pretreated with low or high dosage of PHL for 7 days via intragastric administration once a day before LPS injection. The results showed that PHL pretreatment significantly prevented LPS-induced lung pathological injury and inflammatory response. Meantime, PHL pretreatment also decreased the level of glycolysis in macrophage during ALI. In terms of mechanism, PHL inhibited the mRNA and protein expression of GLUT1. In vitro experiments further showed GLUT1 overexpression in macrophage by infection with lentivirus could abolish the inhibition of inflammation and glycolysis mediated by PHL, suggesting that GLUT1 was essential for the protection of PHL. Taken together, PHL pretreatment may protect against LPS-induced ALI by inhibiting glycolysis in macrophage in a GLUT1-dependent manner, which may be a candidate against ALI in the future.

Triptolide Induces Liver Injury by Regulating Macrophage Recruitment and Polarization via the Nrf2 Signaling Pathway

Triptolide (TP) has limited usage in clinical practice due to its side effects and toxicity, especially liver injury. Hepatic macrophages, key player of liver innate immunity, were found to be recruited and activated by TP in our previous study. The nuclear factor-erythroid-2-related factor 2 (Nrf2) pathway exerts a protective role in TP-induced liver damage, but its effect on the functions of hepatic macrophage has not been elucidated. Here, we determined whether TP can regulate the recruitment and polarization of hepatic macrophages by inhibiting Nrf2 signaling cascade. Our results demonstrated that TP inhibited the Nrf2 signaling pathway in hepatic macrophages. The changes in hepatic macrophages were responsible for the increased susceptibility toward inflammatory stimuli, and hence, TP pretreatment could induce severe liver damage upon the stimulation of a nontoxic dose of lipopolysaccharides. In addition, the Nrf2 agonist protected macrophages from TP-induced toxicity and Nrf2 deficiency significantly aggravated liver injury by enhancing the recruitment and M1 polarization of hepatic macrophages. This study suggests that Nrf2 pathway-mediated hepatic macrophage polarization plays an essential role in TP-induced liver damage, which can serve as a potential therapeutic target for preventing hepatotoxicity induced by TP.

Flavonoid Phloretin Inhibits Adipogenesis and Increases OPG Expression in Adipocytes Derived from Human Bone-Marrow Mesenchymal Stromal-Cells

Phloretin (a flavonoid abundant in apple), has antioxidant, anti-inflammatory, and glucose-transporter inhibitory properties. Thus, it has interesting pharmacological and nutraceutical potential. Bone-marrow mesenchymal stem cells (MSC) have high differentiation capacity, being essential for maintaining homeostasis and regenerative capacity in the organism. Yet, they preferentially differentiate into adipocytes instead of osteoblasts with aging. This has a negative impact on bone turnover, remodeling, and formation. We have evaluated the effects of phloretin on human adipogenesis, analyzing MSC induced to differentiate into adipocytes. Expression of adipogenic genes, as well as genes encoding OPG and RANKL (involved in osteoclastogenesis), protein synthesis, lipid-droplets formation, and apoptosis, were studied. Results showed that 10 and 20 µM phloretin inhibited adipogenesis. This effect was mediated by increasing beta-catenin, as well as increasing apoptosis in adipocytes, at late stages of differentiation. In addition, this chemical increased OPG gene expression and OPG/RANKL ratio in adipocytes. These results suggest that this flavonoid (including phloretin-rich foods) has interesting potential for clinical and regenerative-medicine applications. Thus, such chemicals could be used to counteract obesity and prevent bone-marrow adiposity. That is particularly useful to protect bone mass and treat diseases like osteoporosis, which is an epidemic worldwide.