Ferulic acid attenuates microglia-mediated neuroinflammation in retinal degeneration

The neuroprotective effects of ferulic acid in toxin-induced models of Parkinson's disease: A review

Parkinson's disease is predominantly caused by dopaminergic neuron loss in the substantia nigra pars compacta and the accumulation of alpha-synuclein protein. Though the general consensus is that several factors, such as aging, environmental factors, mitochondrial dysfunction, accumulations of neurotoxic alpha-synuclein, malfunctions of the lysosomal and proteasomal protein degradation systems, oxidative stress, and neuroinflammation, are involved in the neurodegeneration process of Parkinson's disease, the precise mechanism by which all of these factors are triggered remains unknown. Typically, neurotoxic compounds such as rotenone, 6-hydroxydopamine, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-methyl 4-phenyl pyridinium (mpp+), paraquat, and maneb are used to Preclinical models of Parkinson's disease Ferulic acid is often referred to by its scientific name, 4-hydroxy-3-methoxycinnamic acid (C10H10O4), and is found naturally in cereals, fruits, vegetables, and bee products. This substance exhibits neuroprotective effects against Parkinson's disease because of its intriguing potential, which includes anti-inflammatory and antioxidant qualities. This review goes into additional detail about Parkinson's disease and the neuroprotective properties of ferulic acid that may help prevent the condition.

Navigating the future of retinitis pigmentosa treatments: A comprehensive analysis of therapeutic approaches in rd10 mice

Retinitis pigmentosa (RP) is a degenerative disease, caused by genetic mutations that lead to a loss in photoreceptors. For research on RP, rd10 mice, which carry mutations in the phosphodiesterase (PDE) gene, exhibit degenerative patterns comparable to those of patients with RP, making them an ideal model for investigating potential treatments. Although numerous studies have reported the potential of biochemical drugs, gene correction, and stem cell transplantation in decelerating rd10 retinal degeneration, a comprehensive review of these studies has yet to be conducted. Therefore, here, a comparative analysis of rd10 mouse treatment research over the past decade was performed. Our findings suggest that biochemical drugs capable of inhibiting the inflammatory response may be promising therapeutics. Additionally, significant progress has been made in the field of gene therapy; nevertheless, challenges such as strict delivery requirements, bystander editing, and off-target effects still need to be resolved. Nevertheless, secretory function is the only unequivocal protective effect of stem cell transplantation. In summary, this review presents a comprehensive analysis and synthesis of the treatment approaches employing rd10 mice as experimental subjects, describing a clear pathway for future RP treatment research and identifies potential clinical interventions.

Involvement of NLRP3 inflammasome pathway in the protective mechanisms of ferulic acid and p-coumaric acid in LPS-induced sickness behavior and neuroinflammation in mice

Ferulic acid (FA) and p-coumaric acid (PCA) are abundantly present in commonly consumed food and beverages. Being polyphenolic compounds, they have been explored for their antioxidant and anti-inflammatory properties. Based on our previous study, we selected these two compounds to further investigate their potential in lipopolysaccharide (LPS)-induced sickness behavior and the ensuing neuroinflammation by specifically focusing on the NLRP3 inflammasome pathway. Male Swiss albino mice were divided into nine groups (n = 6) consisting of Normal Control, LPS, fluoxetine (FLX), FA40, FA160, FA640, PCA40, PCA160, and PCA640 respectively. Each group received respective FA or PCA treatment except Normal Control and LPS, which received the vehicle, carboxymethylcellulose 0.25% w/v. All groups were challenged with LPS 1.5 mg/kg, intraperitoneally except the Normal Control group, which received saline. Behavioral assessments were performed between 1-2 h, and the whole brains were collected at 3 h post-LPS administration. LPS-induced sickness behavior was characterized by significantly reduced spontaneous activity and high immobility time. The expression of NLRP3, ASC, caspase-1 and IL-1β was significantly increased, along with the levels of brain IL-1β suggesting the assembly and activation of NLRP3 inflammasome pathway. Furthermore, the major cytokines involved in sickness behavior, IL-6 and TNF-α were also significantly elevated with the accompanied lipid peroxidation. The results of this study emphasize that within the employed dose ranges of both FA and PCA, both the compounds were effective at blocking the activation of the NLRP3 inflammasome pathway and thereby reducing the release of IL-1β and the sickness behavior symptoms. There was a prominent effect on cytokine levels and lipid peroxidation as well.

Neurovascular glial unit: A target of phytotherapy for cognitive impairments

BACKGROUND

Neurovascular glial unit (NVGU) dysfunction has been reported to be an early and critical event in the pathophysiology of Alzheimer's disease (AD) and vascular dementia (VD). Although herbal medicines, with their favorable safety profiles and low adverse effects, have been suggested to be useful for the treatment of cognitive impairment, the potential role of the NVGU as the target of the effects of herbal medicines is still unclear.

PURPOSE

This review aimed to retrieve evidence from experimental studies of phytopharmaceuticals targeting the NVGU for the treatment of cognitive impairment in AD and VD, and discussed the potential of phytopharmaceuticals to improve cognitive impairment from the perspective of the NVGU.

STUDY DESIGN AND METHODS

We systematically searched PubMed, Google Scholar, Web of Science, and CNKI. The keywords used for searching information on the NVGU in the treatment of cognitive impairments included "Alzheimer's disease," "Vascular dementia," "Herbal medicines," "Natural products," "Neurovascular," "Adverse reaction," and "Toxicity, etc." We selected studies on the basis of predefined eligibility criteria.

RESULTS

NVGU mainly consists of endothelial cells, pericytes, astrocytes, microglia, oligodendrocytes, and neurons, and damage to these cells can induce cognitive impairment by impairing the blood-brain barrier (BBB) and cerebral blood flow (CBF) as well as neuronal function. The active components of herbal medicines, including Ginkgo biloba L., Ginseng Radix et Rhizoma, Epimedium Folium, Chuanxiong Rhizoma, Carthami flos, and Acorus tatarinowii Schott, as well as traditional Chinese medicine prescriptions have shown the potential to improve BBB function and increase CBF to prevent cognitive impairment by inhibiting astrocyte and microglia activation, protecting oligodendrocyte myelin function, reducing neuronal apoptosis, and promoting angiogenesis.

CONCLUSIONS

Herbal medicines demonstrate great potential to prevent cognitive impairment. Multiple components from herbal medicines may function through different signaling pathways to target the NVGU. Future studies using novel drug-carrier or delivery systems targeting the NVGU will certainly facilitate the development of phytopharmaceuticals for AD and VD.

Involvement of indoleamine 2, 3-dioxygenase (IDO) and brain-derived neurotrophic factor (BDNF) in the neuroprotective mechanisms of ferulic acid against depressive-like behaviour

OBJECTIVE

Ferulic acid (FA) is a common food ingredient that is abundantly present in various routinely consumed food and beverages. Like many cinnamic acid derivatives, FA produces wide-ranging effects in a dose-dependent manner and various studies link FA consumption with reduced risk of depressive disorders. The aim of this study was to exploit the neuroprotective mechanisms of FA including indoleamine 2,3-dioxygenase (IDO), brain-derived neurotrophic factor (BDNF), and other pro-inflammatory cytokines by employing lipopolysaccharide (LPS)-induced depressive-like behaviour model.

METHODS

C57BL/6J male mice were divided into 4 groups consisting of saline (SAL), LPS, FA and Imipramine (IMI). Animals were pretreated orally with FA (10 mg/kg) and IMI (10 mg/kg) for 21 days once daily and all groups except SAL were challenged with LPS (0.83 mg/kg) intraperitoneally on day 21.

RESULTS

LPS administration produced a biphasic change in the behaviour of the animals where the animals lost a significant weight and express high immobility time at 24 h. Proinflammatory cytokines including, TNF-α, IL-6, IL-1β, and IFN-γ were significantly increased along with increased lipid peroxidation and reduced BDNF. Furthermore, the increased kynurenine to tryptophan ratio was indicative of elevated IDO activity.

CONCLUSION

The results of this study emphasise that low dose of FA is effective in attenuating depressive-like behaviour by modulating IDO, BDNF and reducing neuroinflammation.

New Insights on Dietary Polyphenols for the Management of Oxidative Stress and Neuroinflammation in Diabetic Retinopathy

Diabetic retinopathy (DR) is a neurodegenerative and vascular pathology that is considered one of the leading causes of blindness worldwide, resulting from complications of advanced diabetes mellitus (DM). Current therapies consist of protocols aiming to alleviate the existing clinical signs associated with microvascular alterations limited to the advanced disease stages. In response to the low resolution and limitations of the DR treatment, there is an urgent need to develop more effective alternative therapies to optimize glycemic, vascular, and neuronal parameters, including the reduction in the cellular damage promoted by inflammation and oxidative stress. Recent evidence has shown that dietary polyphenols reduce oxidative and inflammatory parameters of various diseases by modulating multiple cell signaling pathways and gene expression, contributing to the improvement of several chronic diseases, including metabolic and neurodegenerative diseases. However, despite the growing evidence for the bioactivities of phenolic compounds, there is still a lack of data, especially from human studies, on the therapeutic potential of these substances. This review aims to comprehensively describe and clarify the effects of dietary phenolic compounds on the pathophysiological mechanisms involved in DR, especially those of oxidative and inflammatory nature, through evidence from experimental studies. Finally, the review highlights the potential of dietary phenolic compounds as a prophylactic and therapeutic strategy and the need for further clinical studies approaching the efficacy of these substances in DR management.

Ferulic acid as a therapeutic agent in depression: Evidence from preclinical studies

Depression is a common but severe mood disorder with a very high prevalence across the general population. Depression is of global concern and poses a threat to human physical and mental health. Ferulic acid (FA) is a natural active ingredient that has antioxidative, anti-inflammatory, and free radical scavenging properties. Furthermore, studies have shown that FA can exert antidepressant effects through a variety of mechanisms. The aim of the review was to comprehensively elucidate the mechanisms in FA that alleviate depression using animal models. The in vivo (animal) studies on the mechanism of FA treatment of depression were searched in PubMed, Chinese National Knowledge Infrastructure, Baidu academic, and Wan fang databases. Thereafter, the literature conclusions were summarized accordingly. Ferulic acid was found to significantly improve the depressive-like behaviors of animal models, suggesting that FA is a potential natural product in the treatment of depression. The mechanisms are achieved by enhancing monoamine oxidase A (MOA) activity, inhibiting microglia activation and inflammatory factor release, anti-oxidative stress, promoting hippocampal nerve regeneration, increasing brain-derived neurotrophic factor secretion, regulating gut microbiome, and activating protein kinase B/collapsin response mediator protein 2 (AKT/CRMP2) signaling pathway. Ferulic acid produces significant antidepressant effects in animal depression models through various mechanisms, suggesting its potential value as a treatment of depression. However, clinical research trials involving FA are required further to provide a solid foundation for its clinical application.

Ferulic acid alleviates high fat diet-induced cognitive impairment by inhibiting oxidative stress and apoptosis

Cognitive impairment has become a major public health problem. Growing evidence suggests that high-fat diet (HFD) can cause cognitive dysfunction and increase the risk of dementia. However, effective treatment for cognitive impairment is not available. Ferulic acid (FA) is a single phenolic compound with anti-inflammatory and antioxidant properties. Nevertheless, its role in regulating learning and memory in HFD-fed mice and the underlying mechanism remains unclear. In this study, we aimed to identify the neuroprotective mechanisms of FA in HFD induced cognitive impairment. We found that FA improved the survival rate of HT22 cells treated with palmitic acid (PA), inhibited cell apoptosis, and reduced oxidative stress via the IRS1/PI3K/AKT/GSK3β signaling pathway; Furthermore, FA treatment for 24 weeks improved the learning and memory of HFD-fed mice and decreased hyperlipidemia. Moreover, the expression of Nrf2 and Gpx4 proteins were decreased in HFD-fed mice. After FA treatment, the decline of these proteins was reversed. Our study showed that the neuroprotective effect of FA on cognitive impairment was related to the inhibition of oxidative stress and apoptosis and regulation of glucose and lipid metabolism. These findings suggested that FA can be developed as a potential agent for the treatment of HFD-induced cognitive impairment.

Ferulic acid alleviates sciatica by inhibiting peripheral sensitization through the RhoA/p38MAPK signalling pathway

BACKGROUND

Nonsteroidal anti-inflammatory drugs are used to relieve sciatica, but their effects are not satisfactory.

PURPOSE

This study aimed to explore the therapeutic effects of ferulic acid on sciatica.

METHODS

Thirty-two SD rats were randomly divided into 4 groups, i.e., sham operation group, chronic constriction injury (CCI) group, mecobalamin group, and ferulic acid group. We conducted behavioural tests, ELISA, PCR, Western blots, and immunofluorescence analysis. Specific inhibitors were used in cell experiments to explore the related mechanisms.

RESULTS

Thermal hyperalgesia was induced after CCI operation, and ferulic acid relieved thermal hyperalgesia. In addition, ferulic acid decreased the IL1β, IL6, TNF-α, and CRP mRNA levels; the IBA-1, iNOS, IL1β, RhoA, RhoA-GTP, COX2, Rock1, TRPV1, TRPA1, and p-p38MAPK levels in dorsal root ganglion (DRG) neurons; and the LPS, CRP, substance P (SP), and prostaglandin E2 (PGE2) levels in serum, and these levels were higher in the CCI group. In the cell experiments, LPS induced M1 polarization of GMI-R1 cells via the RhoA/Rock pathway. Ferulic acid attenuated LPS-induced M1 polarization by decreasing the levels of M1 polarization markers, including IL1β, IL6, TNF-α, iNOS, and CD32, and increased M2 polarization by increasing the levels of M2 polarization markers, including CD206 and Arg-1. LPS treatment clearly increased the iNOS, IL1β, RhoA, Rock1, Rock2 and p-p38 MAPK levels and reduced Arg-1 expression, and ferulic acid reversed these changes.

CONCLUSION

Ferulic acid can inhibit peripheral sensitization by reducing the levels of inflammatory factors, TRPA1 and TRPV1 through the RhoA/p38 MAPK pathway to alleviate sciatica.

Generation of a gene-corrected human iPSC line (CSUASOi004-A-1) from a retinitis pigmentosa patient with heterozygous c.2699 G>A mutation in the PRPF6 gene

Retinitis pigmentosa (RP) is one of the most common inherited retinal diseases characterized by nyctalopia, progressive vision loss and visual field contraction. we previously generated an induced pluripotent stem cell line (CSUASOi004-A) from a RP patient with heterozygous PRPF6 c.2699 G>A (p.R900H) mutation. Here we corrected the PRPF6 c.2699 G>A mutation genetically using CRISPR/Cas9 technology to generate an isogenic control (CSUASOi004-A-1), which can provide a valuable resource in the research of the disease.

Ferulic acid alleviates retinal neovascularization by modulating microglia/macrophage polarization through the ROS/NF-κB axis

Inflammation plays a pivotal role in ischemia-induced retinal neovascularization. Targeting microglia/macrophage-based neuroinflammation presents a promising therapeutic strategy. Ferulic acid (FA), a natural and active ingredient in plants, exerts favorable anti-oxidative and anti-inflammatory activities. In this study, we investigated the inhibitory effect of FA against hypoxia-induced retinal angiogenesis using cultured retinal vascular endothelial cells and an oxygen-induced retinopathy mouse (OIR) model. The immunoregulatory effect of FA on microglia/macrophage polarization was evaluated by detecting the expression of specific markers for both pro-inflammatory “M1” and anti-inflammatory “M2” phenotypes using co-immunostaining and polymerase chain reaction assays. The underlying molecular mechanism upon FA treatment was also explored. The results showed that FA supplement markedly inhibited retinal pathological angiogenesis both in vivo and in vitro. In addition, FA switched microglia/macrophage polarization from “M1” towards “M2” phenotype and alleviated the inflammatory response. Mechanically, the anti-angiogenic and anti-inflammatory properties of FA were mainly due to blockade of the ROS/NF-κB pathway. Our data demonstrated an anti-angiogenic effect of FA through regulating M1-to-M2 microglia/macrophage polarization, suggesting a potential therapeutic strategy for retinal neovascular diseases.

Aberrant Retinal Pigment Epithelial Cells Derived from Induced Pluripotent Stem Cells of a Retinitis Pigmentosa Patient with the PRPF6 Mutation

Pre-mRNA processing factors (PRPFs) are vital components of the spliceosome and are involved in the physiological process necessary for pre-mRNA splicing to mature mRNA. As an important member, PRPF6 mutation resulting in autosomal dominant retinitis pigmentosa (adRP) is not common. Recently, we reported the establishment of an induced pluripotent stem cells (iPSCs; CSUASOi004-A) model by reprogramming the peripheral blood mononuclear cells of a PRPF6-related adRP patient, which could recapitulate a consistent disease-specific genotype. In this study, a disease model of retinal pigment epithelial (RPE) cells was generated from the iPSCs of this patient to further investigate the underlying molecular and pathological mechanisms. The results showed the irregular morphology, disorganized apical microvilli and reduced expressions of RPE-specific genes in the patient’s iPSC-derived RPE cells. In addition, RPE cells carrying the PRPF6 mutation displayed a decrease in the phagocytosis of fluorescein isothiocyanate-labeled photoreceptor outer segments and exhibited impaired cell polarity and barrier function. This study will benefit the understanding of PRPF6-related RPE cells and future cell therapy.

Potential Biomarkers and Drugs for Nanoparticle-Induced Cytotoxicity in the Retina: Based on Regulation of Inflammatory and Apoptotic Genes

The eye is a superficial organ directly exposed to the surrounding environment. Thus, the toxicity of nanoparticle (NP) pollutants to the eye may be potentially severer relative to inner organs and needs to be monitored. However, the cytotoxic mechanisms of NPs on the eyes remain rarely reported. This study was to screen crucial genes associated with NPs-induced retinal injuries. The gene expression profiles in the retina induced by NPs [GSE49371: Au20, Au100, Si20, Si100; GSE49048: presumptive therapeutic concentration (PTC) TiO₂, 10PTC TiO₂] and commonly used retinal cell injury models (optic nerve injury procedure: GSE55228, GSE120257 and GSE131486; hypoxia exposure: GSE173233, GSE151610, GSE135844; H₂O₂ exposure: GSE122270) were obtained from the Gene Expression Omnibus database. A total of 381 differentially expressed genes (including 372 mRNAs and 9 lncRNAs) were shared between NP exposure and the optic nerve injury model when they were compared with their corresponding controls. Function enrichment analysis of these overlapped genes showed that Tlr2, Crhbp, Ccl2, Cxcl10, Fas, Irf8, Socs3, Stat3, Gbp6, Casp1 and Syk were involved in inflammatory- and apoptotic-related processes. Protein-protein interaction network analysis revealed eight of them (Tlr2, Ccl2, Cxcl10, Irf8, Socs3, Stat3, Casp1 and Syk) were hub genes. Moreover, Socs3 could interact with upstream Stat3 and downstream Fas/Casp1/Ccl2/Cxcl10; Irf8 could interact with upstream Tlr2, Syk and downstream Cxcl10. Competing endogenous RNAs network analysis identified Socs3, Irf8, Gdf6 and Crhbp could be regulated by lncRNAs and miRNAs (9330175E14Rik-mmu-miR-762-Socs3, 6430562O15Rik-mmu-miR-207-Irf8, Gm9866-mmu-miR-669b-5p-Gdf6, 4933406C10Rik-mmu-miR-9-5p-Crhbp). CMap-CTD database analyses indicated the expression levels of Tlr2, Ccl2, Cxcl10, Fas, Irf8, Socs3, Stat3, Gbp6, Casp1 and Syk could be reversed by folic acid. Crhbp and Gdf6 were also verified to be downregulated, while Tlr2, Ccl2, Irf8, Socs3 and Stat3 were upregulated in hypoxia/H₂O₂-induced retinal injury models. Hereby, our findings suggest that Crhbp, Irf8, Socs3 and Gdf6 as well as their upstream mRNAs, lncRNAs and miRNAs may be potential monitoring biomarkers and therapeutic targets for NP-induced retinal injuries. Folic acid supplementation may be a preventive and therapeutic approach.

Effects and underlying mechanisms of food polyphenols in treating gouty arthritis: A review on nutritional intake and joint health

Gouty arthritis, one of the most severe and common forms of arthritis, is characterized by monosodium urate crystal deposition in joints and surrounding tissues. Epidemiological evidence indicates that gouty arthritis incidence is sharply rising globally. Polyphenols are found in many foods and are secondary metabolites in plant foods. The anti-inflammatory and antioxidant effects of food polyphenols have been extensively studied in many inflammatory chronic diseases. Research has suggested that many food polyphenols have excellent anti-gouty arthritis effects. The mechanisms mainly include (a) inhibiting xanthine oxidase activity; (b) reducing the levels of inflammatory cytokines and chemokines; (c) inhibiting the activation of signaling pathways and the NLRP3 inflammasome; and (d) reducing oxidative stress. This paper reviews the research progress and pathogenesis of gouty arthritis and introduces the mechanisms of food polyphenols in treating gouty arthritis, which aims to explore the potential of functional foods in the treatment of gouty arthritis. PRACTICAL APPLICATIONS: The incidence rate of gouty arthritis has increased sharply worldwide, which has seriously affected people's quality of life. According to the current research progress, food polyphenols alleviate gouty arthritis through anti-inflammatory and antioxidant effects. This paper reviews the research progress and molecular pathogenesis of gouty arthritis and introduces the mechanisms of food-derived polyphenols in the treatment of gouty arthritis, which is helpful to the prevention and treatment of gouty arthritis.

Recent Advances in Biological Activity, New Formulations and Prodrugs of Ferulic Acid

Trans-ferulic acid (FA) is a derivative of 4-hydroxycinnamic acid, which is found in many food products, fruits and beverages. It has scientifically proven antioxidant, anti-inflammatory and antibacterial properties. However, its low ability to permeate through biological barriers (e.g., the blood-brain barrier, BBB), its low bioavailability and its fast elimination from the gastrointestinal tract after oral administration limit its clinical use, e.g., for the treatment of neurodegenerative diseases, such as Alzheimer's disease. Therefore, new nanotechnological approaches are developed in order to regulate intracellular transport of ferulic acid. The objective of this review is to summarize the last decade's research on biological properties of ferulic acid and innovative ways of its delivery, supporting pharmacological therapy.