Bixin Attenuates Experimental Autoimmune Encephalomyelitis by Suppressing TXNIP/NLRP3 Inflammasome Activity and Activating NRF2 Signaling

Targeting Nrf2 by bioactive peptides alleviate inflammation: expanding the role of gut microbiota and metabolites

Inflammation is a complex process that usually refers to the general response of the body to the harmful stimuli of various pathogens, tissue damage, or exogenous pollutants. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates cellular defense against oxidative damage and toxicity by expressing genes related to oxidative stress response and drug detoxification. In addition to its antioxidant properties, Nrf2 is involved in many other important physiological processes, including inflammation and metabolism. Nrf2 can bind the promoters of antioxidant genes and upregulates their expressions, which alleviate oxidation-induced inflammation. Nrf2 has been shown to upregulate heme oxygenase-1 expression, which promotes NF-κB activation and is closely related with inflammation. Nrf2, as a key factor in antioxidant response, is closely related to the expressions of pro-inflammatory factors, NF-κB pathway and cell metabolism. Bioactive peptides come from a wide range of sources and have many biological functions. Increasing evidence indicates that bioactive peptides have potential anti-inflammatory activities. This article summarized the sources, absorption and utilization of bioactive peptides and their role in alleviating inflammation via Nrf2 pathway. Bioactive peptides can also regulate gut microbiota and alter metabolites, which regulates the Nrf2 pathway through novel pathway and supplement the anti-inflammatory mechanisms of bioactive peptides. This review provides a reference for further study on the anti-inflammatory effect of bioactive peptides and the development and utilization of functional foods.

Characteristics of peripheral blood mononuclear cells and potential related molecular mechanisms in patients with autoimmune hepatitis: a single-cell RNA sequencing analysis

Autoimmune hepatitis (AIH) is an immune disorder characterized by hypergammaglobulinemia, autoantibodies, and chronic active hepatitis on liver histology. However, immune cell population characteristics in AIH patients remain poorly understood. This study was designed to analyze peripheral blood mononuclear cell (PBMC) characteristics in AIH through single-cell RNA sequencing (scRNA-seq) and explore potential AIH-related molecular mechanisms. We generated 3690 and 3511 single-cell transcriptomes of PBMCs pooled from 4 healthy controls (HCs) and 4 AIH patients, respectively, by scRNA-seq. These pooled PBMC transcriptomes were used for cell cluster identification and differentially expressed gene (DEG) identification. GO functional enrichment analysis was performed on the DEGs to determine the most active AIH immune cell biological functions. Although the PCA-based uniform manifold approximation and projection (UMAP) algorithm was used to cluster cells with similar expression patterns in the two samples, 87 up- and 12 downregulated DEGs were retained in monocytes and 101 up- and 15 downregulated DEGs were retained in NK cells from AIH PBMCs. Moreover, enriched GO terms in the PBMC-derived monocyte and NK cell clusters were related mainly to antigen processing and presentation, IFN-γ-mediated signaling, and neutrophil degranulation and activation. These potential molecular mechanisms may be important targets for AIH treatment.

NLRP3 inflammasome and its role in autoimmune diseases: A promising therapeutic target

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines IL-1β and IL-18. Numerous studies have highlighted its crucial role in the pathogenesis and development of inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, autoimmune thyroid diseases, and other autoimmune diseases. Therefore, investigating the underlying mechanisms of NLRP3 in disease and targeted drug therapies holds clinical significance. This review summarizes the structure, assembly, and activation mechanisms of the NLRP3 inflammasome, focusing on its role and involvement in various autoimmune diseases. This review also identifies studies where the involvement of the NLRP3 inflammasome in the disease mechanism within the same disease appears contradictory, as well as differences in NLRP3-related gene polymorphisms among different ethnic groups. Additionally, the latest therapeutic advances in targeting the NLRP3 inflammasome for autoimmune diseases are outlined, and novel clinical perspectives are discussed. Conclusively, this review provides a consolidated source of information on the NLRP3 inflammasome and may guide future research efforts that have the potential to positively impact patient outcomes.

Serum carotenoid levels are positively associated with DNA methylation of thioredoxin-interacting protein

Background: Carotenoids have been reported to exert protective effects against age-related diseases via changes in DNA methylation. Although lower thioredoxin-interacting protein (TXNIP) DNA methylation is associated with age-related diseases, only a few studies have investigated the factors influencing TXNIP DNA methylation. Carotenoids may be a factor linking TXNIP to specific pathophysiological functions. The aim of this study was to examine whether serum carotenoid levels are associated with TXNIP DNA methylation levels. Methods: We conducted a cross-sectional study using 376 health examination participants (169 men). DNA methylation levels were determined using a pyrosequencing assay. Serum carotenoid levels were determined by high-performance liquid chromatography. Multivariable regression analyses were performed to examine the associations between TXNIP DNA methylation levels and serum carotenoid levels with adjustment for age, BMI, HbA1c, CRP, smoking habits, alcohol consumption, exercise habits, and percentage of neutrophils. Results: Multiple linear regression analyses showed that TXNIP DNA methylation levels were positively associated with serum levels of zeaxanthin/lutein (β [95%CI]: 1.935 [0.184, 3.685]), β-cryptoxanthin (1.447 [0.324, 2.570]), α-carotene (1.061 [0.044, 2.077]), β-carotene (1.272 [0.319, 2.226]), total carotenes (1.255 [0.040, 2.469]), total xanthophylls (2.133 [0.315, 3.951]), provitamin A (1.460 [0.402, 2.519]), and total carotenoids (1.972 [0.261, 3.683]) in men (all p<0.05). Of these, provitamin A showed the stronger association (standardized β=0.216). No significant association of TXNIP DNA methylation and serum carotenoid was observed in women. Conclusions: The findings of this study suggest that carotenoid intake may protect against age-related diseases by altering TXNIP DNA methylation status in men.

Natural products for the treatment of chemotherapy-related cognitive impairment and prospects of nose-to-brain drug delivery

Chemotherapy-related cognitive deficits (CRCI) as one of the common adverse drug reactions during chemotherapy that manifest as memory, attention, and executive function impairments. However, there are still no effective pharmacological therapies for the treatment of CRCI. Natural compounds have always inspired drug development and numerous natural products have shown potential therapeutic effects on CRCI. Nevertheless, improving the brain targeting of natural compounds in the treatment of CRCI is still a problem to be overcome at present and in the future. Accumulated evidence shows that nose-to-brain drug delivery may be an excellent carrier for natural compounds. Therefore, we reviewed natural products with potential anti-CRCI, focusing on the signaling pathway of these drugs' anti-CRCI effects, as well as the possibility and prospect of treating CRCI with natural compounds based on nose-to-brain drug delivery in the future. In conclusion, this review provides new insights to further explore natural products in the treatment of CRCI.

Quercetin alleviates lipopolysaccharide‑induced acute lung injury by inhibiting ferroptosis via the Sirt1/Nrf2/Gpx4 pathway

Acute lung injury (ALI) causes high morbidity and mortality rates in critically ill patients, and there are currently no effective therapeutic drugs. Ferroptosis is a newly discovered mode of regulated cell death that contributes to the progression of ALI. Quercetin possesses anti‑inflammatory and antioxidant properties. However, whether quercetin can protect against lipopolysaccharide (LPS)‑induced ALI by inhibiting ferroptosis and its underlying mechanisms remains unclear. The present study evaluated the protective effects of quercetin and underlying molecular mechanisms in LPS‑induced ALI by establishing an ALI mouse model and an alveolar epithelial cell injury model via treatment of the mice or alveolar epithelial cells with LPS. Mouse lung injury was assessed by evaluating the histological lung injury score, bronchoalveolar lavage fluid cell count and inflammatory cytokine levels; alveolar epithelial cell injury was assessed by Cell counting kit‑8, lactate dehydrogenase and EDU assays; and ferroptosis was assessed by detecting the changes in the levels of malondialdehyde, glutathione, iron, glutathione peroxidase 4 (Gpx4) and 4‑hydroxynonenal in vivo and vitro. The present study indicated that quercetin effectively ameliorated LPS‑induced ALI in the mouse model by reducing histopathological changes, proinflammatory cytokine release and reactive oxygen species generation and inhibiting ferroptosis. Quercetin significantly decreased ferroptosis and improved the proliferative ability of LPS‑treated alveolar epithelial cells. Additionally, it was demonstrated that quercetin markedly enhanced the alveolar epithelial barrier, as evidenced by the upregulation of tight junction protein expression both in vivo and in vitro. Mechanistically, quercetin effectively activated the sirtuin 1 (Sirt1)/nuclear factor erythroid 2‑related factor 2 (Nrf2)/Gpx4 signaling pathway, and targeted in vivo inhibition or in vitro knockdown of Sirt1 significantly reduced the anti‑ferroptotic functions of quercetin. In conclusion, the results demonstrated that quercetin exerts its therapeutic effects against LPS‑induced ALI by inhibiting ferroptosis via the activation of the Sirt1/Nrf2/Gpx4 signaling pathway.

Exploring bixin from Bixa orellana L. seeds: quantification and in silico insights into its anti-cancer potential

Bixin, the key pigment of Bixa orellana L., is an apo-carotenoid found in the seed arils. The present study aimed to quantitatively determine the bixin content of seeds and explore its anti-cancer activity through in silico studies. The bixin content from the seeds of the local genotype, TNMTP8, quantified by RP-HPLC was 4.58 mg per gram. The prediction of pharmacological activity suggested that bixin may serve as a BRAF, MMP9, TNF expression inhibitors, and TP53 expression enhancer. According to molecular docking analysis, bixin interacted with eight different skin cancer targets and had the lowest binding energy compared to the standard drug, 5-fluorouracil. The binding score between bixin and the targets ranged from -4.7 to -8.7 kcal/mol. The targets BRAF and SIRT3 interacted well with bixin, with binding energies as low as -8.3 and -8.7 kcal/mol, respectively. Hence, the dynamic behavior of these two docked complexes throughout a 500 ns trajectory run was investigated further. The Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF) values, and total contacts as a function of time recorded during scrutiny suggest that both complexes were stable. This was validated by post-molecular dynamics analysis using Molecular Mechanics Generalized Born Surface Area (MM-GBSA). Principal component analysis (PCA) was used to analyze the significant differences in motion exhibited by BRAF-Bixin and SIRT3-Bixin. The results showed that bixin is a promising source for potential treatment interventions in skin cancer therapies.Communicated by Ramaswamy H. Sarma.

Therapeutic potential of bixin on inflammation: a mini review

Chronic inflammation is the underlying mechanism for many diseases. Thus, inflammatory signaling pathways are valuable targets for new treatment modalities. Natural products have gained interest as a potential source of bioactive compounds which provide health benefits in combating inflammatory-related diseases. Recent reports have linked the medicinal values of Bixa orellana L. with its anti-inflammatory activities. Therefore, this review aims to examine the therapeutic potential of bixin, a major bioactive constituent found in the seeds of B. orellana, on inflammatory-related diseases based on existing in vitro and in vivo evidence. Additionally, the anti-inflammatory mechanism of bixin via signaling pathways is explored and possible toxic effects are addressed. The findings suggest that bixin may ameliorate inflammation via inhibition of toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-κB), phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) and thioredoxin-interacting protein/NOD-like receptor protein 3 (TXNIP/NLRP3) inflammasome mechanisms. More well-planned clinical studies should be performed to verify its effectiveness and safety profile.

Downregulated PGK1 attenuates cerebral ischemia-reperfusion injury by reversing neuroinflammation and oxidative stress through the Nrf2/ARE pathway

Understanding the role and mechanism of astrocytes in inflammation and oxidative response is crucial for developing therapeutic strategies to reduce inflammation and oxidative injury in cerebral ischemia-reperfusion injury (CIRI). In this study, we investigated the regulatory effects of phosphoglycerate kinase 1 (PGK1) on inflammation and oxidative response after CIRI in male adult Sprague-Dawley (SD) rats and using primary astrocytes obtained from neonatal SD rats, and explored its related mechanisms. We established a rat model of middle cerebral artery occlusion-reperfusion (MCAO/R) by suture occlusion, and an oxygen-glucose deprivation/reoxygenation model of astrocytes using oxygen-free, glucose-free, and serum-free cultures. AAV8-PGK1-GFP was injected into the left ventricle 24 h before modeling. Real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, co-immunoprecipitation (CoIP) assay, fluorescence in situ hybridization (FISH), and western blotting were used to elucidate the in-depth mechanisms of PGK1 in CIRI. PGK1 overexpression significantly exacerbated neurological deficits, increased cerebral infarct volume, and aggravated nerve cell injury in rats after MCAO/R. Using FISH and CoIP assays, we verified the localization of PGK1 and Nrf2 in primary astrocytes. Further rescue experiments showed that Nrf2 knockdown eliminated the protective effect of CBR-470-1 (a PGK1 inhibitor) on CIRI. Lastly, we confirmed that PGK1 aggravates CIRI by inhibiting the Nrf2/ARE pathway. In conclusion, our findings suggest that inhibiting PGK1 attenuates CIRI by reducing the release of inflammatory and oxidative factors from astrocytes by activating the Nrf2/ARE signaling pathway.

Therapeutic effect of the total saponin from Panax Japonicus on experimental autoimmune encephalomyelitis by attenuating inflammation and regulating gut microbiota in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizomes of Panax japonicus (RPJ), a traditional herbal medicine, was used for treating arthritis and physical weakness in China from the Ming dynasty. Triterpene saponins are the main bioactive components of RPJ. In this work, for the first time, we evaluate the therapeutic effect of the total saponin from RPJ (TSPJ) on experimental autoimmune encephalomyelitis (EAE) mice induced by myelin oligodendrocyte glycoprotein (MOG) _35-55, a commonly used animal model of Multiple sclerosis (MS).

AIM OF THE STUDY

To evaluate the therapeutic effect of TSPJ on EAE and explored its possible underlying mechanisms.

MATERIALS AND METHODS

EAE was induced by MOG _35-55. Mice were administrated with TSPJ (36.5 mg/kg, 73 mg/kg) and prednisone acetate (positive control) orally once daily up to 28 days postimmunization, and their neurological deficit was scored. Hematoxylin and Eosin (HE), Luxol Fast Blue (LFB), and transmission electron microscopy (TEM) were carried out to evaluate the EAE-induced pathological changes in the brain and spinal cord. IL-17a and Foxp3 levels in central nervous system(CNS)were evaluated by immunohistochemical staining. The changes in IL-1β, IL-6, and TNF-α levels in serum and CNS were measured with ELISA. Quantitative reverse transcription PCR (qRT-PCR) was used to access mRNA expression in CNS of the above indices. The percentages of Th1, Th2, Th17and Treg cells in spleen were determined by Flow Cytometry (FCM). Furthermore, 16S rDNA sequencing was used to detect the intestinal flora of mice in each group. In vitro studies, lipopolysaccharides (LPS)-induced BV2 microglia cells were used and the expression of TLR4, MyD88, p65, and p-p65 in cells was detected by Western blot.

RESULTS

TSPJ treatment significantly alleviated neurological impairment caused by EAE. Histological examination confirmed the protective effects of TSPJ on myelin sheath and the reduction of inflammatory cell infiltration in the brain and spinal cord of EAE mice. TSPJ notably downregulated the ratio of IL-17a/Foxp3 at protein and mRNA levels in CNS, as well as Th17/Treg and Th1/Th2 cell ratios in the spleen of EAE mice. The levels of TNF-α, IL-6, and IL-1β in CNS and peripheral serum also decreased post-TSPJ treatment. In vitro, TSPJ suppressed LPS-induced production of inflammatory factors in BV2 cells via TLR4-MyD88-NF-κB signaling pathway. More importantly, TSPJ interventions altered the composition of gut microbiota and restored the ratio of Firmicutes to Bacteroidetes in EAE mice. Furthermore, Spearman's correlation analysis revealed that a relationship existed between statistically significantly altered genera and CNS inflammatory indices.

CONCLUSION

Our results demonstrated TSPJ had therapeutic effects on EAE. Its anti-neuroinflammation property in EAE was related to modulating gut microbiota and inhibiting TLR4-MyD88-NF-κB signaling pathway. Our study indicated that TSPJ may be a potential candidate for the treatment of MS.

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.

Modulation of p38 MAPK and Nrf2/HO-1/NLRP3 inflammasome signaling and pyroptosis outline the anti-neuroinflammatory and remyelinating characters of Clemastine in EAE rat model

There is vast evidence for the effect of NOD-like receptor protein-3 (NLRP3) inflammasome on multiple sclerosis (MS) pathogenesis. Clemastine (CLM) targets NLRP3 in hypoxic brain injury and promotes oligodendrocyte differentiation. However, no previous study pointed to the link of CLM with inflammasome components in MS. Herein, the study aimed to verify the action of CLM on NLRP3 signaling in experimental autoimmune encephalomyelitis (EAE) as an MS rat model. Homogenate of spinal cord with complete Freund's adjuvant was administered on days 0 and 7 to induce EAE. Rats received either CLM (5 mg/kg/day; p.o.) or MCC950 (2.5 mg/kg/day; i.p) for 15 days starting from the first immunization day. In EAEs' brains, NLRP3 pathway components; total and phosphorylated p38 mitogen-activated protein kinase (MAPK), apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, interleukins 1β and -18 along with pyroptotic marker; gasdermin D (GSDMD) were upregulated. These were accompanied with diminished nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and total antioxidant capacity levels. CLM improved these perturbations as well as signs of MS; weight loss, clinical scores, and motor disorders observed in the open field, hanging wire and rotarod tests. Histopathological examinations revealed improvement in H&E abnormalities and axonal demyelination as shown by luxol fast blue stain in lumbar sections of spinal cord. These CLM's actions were studied in comparison to MCC950 as a well-established selective blocker of the NLRP3 inflammasome. Conclusively, CLM has a protective role against neuroinflammation and demyelination in EAE via its anti-inflammatory and anti-pyroptotic actions.

Grape Seed Extract Attenuates Demyelination in Experimental Autoimmune Encephalomyelitis Mice by Inhibiting Inflammatory Response of Immune Cells

OBJECTIVE

To examine the anti-inflammatory effect of grape seed extract (GSE) in animal and cellular models and explore its mechanism of action.

METHODS

This study determined the inhibitory effect of GSE on macrophage inflammation and Th1 and Th17 polarization in vitro. Based on the in vitro results, the effects and mechanisms of GSE on multiple sclerosis (MS)-experimental autoimmune encephalomyelitis (EAE) mice model were further explored. The C57BL/6 mice were intragastrically administered with 50 mg/kg of GSE once a day from the 3rd day to the 27th day after immunization. The activation of microglia, the polarization of Th1 and Th17 and the inflammatory factors such as tumor necrosis factor- α (TNF- α), interleukin-1 β (IL-1 β), IL-6, IL-12, IL-17 and interferon-γ (IFN-γ) secreted by them were detected in vitro and in vivo by flow cytometry, enzyme linked immunosorbent assay (ELISA), immunofluorescence staining and Western blot, respectively.

RESULTS

GSE reduced the secretion of TNF-α, IL-1 β and IL-6 in bone marrow-derived macrophages stimulated by lipopolysaccharide (P<0.01), inhibited the secretion of TNF-α, IL-1 β, IL-6, IL-12, IL-17 and IFN-γ in spleen cells of EAE mice immunized for 9 days (P<0.05 or P<0.01), and reduced the differentiation of Th1 and Th17 mediated by CD3 and CD28 factors (P<0.01). GSE significantly improved the clinical symptoms of EAE mice, and inhibited spinal cord demyelination and inflammatory cell infiltration. Peripherally, GSE downregulated the expression of toll-like-receptor 4 (TLR4) and Rho-associated kinase (ROCKII, P<0.05 or P<0.01), and inhibited the secretion of inflammatory factors (P<0.01 or P<0.05). In the central nervous system, GSE inhibited the infiltration of CD45⁺CD11b⁺ and CD45⁺CD4⁺ cells, and weakened the differentiation of Th1 and Th17 (P<0.05). Moreover, it reduced the secretion of inflammatory factors (P<0.01), and prevented the activation of microglia (P<0.05).

CONCLUSION

GSE had a beneficial effect on the pathogenesis and progression of EAE by inhibiting inflammatory response as a potential drug and strategy for the treatment of MS.

Multispectroscopic, virtual and in vivo insights into the photoaging defense mediated by the natural food colorant bixin

An upsurge in early onset of photoaging due to repeated skin exposure to environmental stressors such as UV radiation is a challenge for pharmaceutical and cosmeceutical divisions. Current reports indicate severe side effects because of chemical or synthetic inhibitors of matrix metalloproteases (MMPs) in anti-skin aging cosmeceuticals. We evaluated the adequacy of bixin, a well-known FDA certified food additive, as a scavenger of free radicals and its inhibitory mechanism of action on MMP1, collagenase, elastase, and hyaluronidase. The anti-skin aging potential of bixin was evaluated by several biotechnological tools in silico, in vitro and in vivo. Molecular docking and simulation dynamics studies gave a virtual insight into the robust binding interaction between bixin and skin aging-related enzymes. Absorbance and fluorescence studies, enzyme inhibition assays, enzyme kinetics and in vitro bioassays of human dermal fibroblast (HDF) cells highlighted bixin's role as a potent antioxidant and inhibitor of skin aging-related enzymes. Furthermore, in vivo protocols were carried out to study the impact of bixin administration on UVA induced photoaging in C57BL/6 mice skin. Here, we uncover the UVA shielding effect of bixin and its efficacy as a novel anti-photoaging agent. Furthermore, the findings of this study provide a strong foundation to explore the pharmaceutical applications of bixin in several other biochemical pathways linked to MMP1, collagenase, elastase, and hyaluronidase.

Ceramide induces pyroptosis through TXNIP/NLRP3/GSDMD pathway in HUVECs

Background

Pyroptosis of endothelial cells is a new cause of endothelial dysfunction in multiple diseases. Ceramide acts as a potential bioactive mediator of inflammation and increases vascular endothelial permeability in many diseases, whether it can aggravate vascular endothelial injury by inducing cell pyroptosis remains unknown. This study was established to explore the effects of C8-ceramide (C8-Cer) on human umbilical vein vascular endothelial cells (HUVECs) and its possible underlying mechanism.

Methods

HUVECs were exposed to various concentrations of C8-Cer for 12 h, 24 h, 48 h. The cell survival rate was measured using the cell counting kit-8 assay. Western blotting and Real-time polymerase chain reaction (RT-PCR) were used to detect the pyroptosis-releated protein and mRNA expressions, respectively. Caspase-1 activity assay was used to detect caspase-1 activity. Hoechst 33342/propidium iodide double staining and flow cytometry were adopted to measure positive staining of cells. Lactate dehydrogenase release assay and enzyme-linked immunosorbent assay were adopted to measure leakage of cellular contents. FITC method was used to detect the permeability of endothelial cells. ROS fluorescence intensity were detected by flow cytometry.

Results

The viability of HUVECs decreased gradually with the increase in ceramide concentration and time. Ceramide upregulated the expression of thioredoxin interacting protein (TXNIP), NLRP3, GSDMD, GSDMD-NT, caspase-1 and Casp1 p20 at the protein and mRNA level in a dose-dependent manner. It also enhanced the PI uptake in HUVECs and upregulated caspase-1 activity. Moreover, it promoted the release of lactate dehydrogenase, interleukin-1β, and interleukin-18. Meanwhile, we found that ceramide led to increased vascular permeability. The inhibitor of NLRP3 inflammasome assembly, MCC950, was able to disrupt the aforementioned positive loop, thus alleviating vascular endothelial cell damage. Interestingly, inhibition of TXNIP either chemically using verapamil or genetically using small interfering RNA (siRNA) can effectively inhibit ceramide-induced pyroptosis and improved cell permeability. In addition, ceramide stimulated reactive oxygen species (ROS) generation. The pretreatment of antioxidant N-acetylcysteine (NAC), ROS scavenger, blocked the expression of pyroptosis markers induced by C8-cer in HUVECs.

Conclusion

The current study demonstrated that C8-Cer could aggravate vascular endothelial cell damage and increased cell permeability by inducing cell pyroptosis. The results documented that the ROS-dependent TXNIP/NLRP3/GSDMD signalling pathway plays an essential role in the ceramide-induced pyroptosis in HUVECs.

The Multiple Sclerosis Modulatory Potential of Natural Multi-Targeting Antioxidants

Multiple sclerosis (MS) is a complex neurodegenerative disease. Although its pathogenesis is rather vague in some aspects, it is well known to be an inflammatory process characterized by inflammatory cytokine release and oxidative burden, resulting in demyelination and reduced remyelination and axonal survival together with microglial activation. Antioxidant compounds are gaining interest towards the manipulation of MS, since they offer, in most of the cases, many benefits, due to their pleiotropical activity, that mainly derives from the oxidative stress decrease. This review analyzes research articles, of the last decade, which describe biological in vitro, in vivo and clinical evaluation of various categories of the most therapeutically applied natural antioxidant compounds, and some of their derivatives, with anti-MS activity. It also summarizes some of the main characteristics of MS and the role the reactive oxygen and nitrogen species may have in its progression, as well as their relation with the other mechanistic aspects of the disease, in order for the multi-targeting potential of those antioxidants to be defined and the source of origination of such activity explained. Antioxidant compounds with specific characteristics are expected to affect positively some aspects of the disease, and their potential may render them as effective candidates for neurological impairment reduction in combination with the MS treatment regimen. However, more studies are needed in order such antioxidants to be established as recommended treatment to MS patients.

Novel recombinant protein flagellin A N/C attenuates experimental autoimmune encephalomyelitis by suppressing the ROS/NF-κB/NLRP3 signaling pathway

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease characterized by demyelination and neurodegeneration, for which traditional treatment offers limited relief. Microglial/macrophage modulation plays a critical role in the pathogenesis of MS. Oxygen free radical accumulation can induce axonal and nerve cell damage, and further promote MS development. We created a new recombinant protein based on flagellin from Legionella pneumophila named flagellin A with linked C- and N-terminal ends (FLaAN/C), which is an independent intellectual property of our team. We previously showed that FLaAN/C might mitigate radiation-induced damage by inhibiting inflammatory responses and oxidative stress. However, whether FLaAN/C protects against MS remains unknown. Here, we investigated the anti-inflammatory effects of FLaAN/C on mice with experimental autoimmune encephalomyelitis (EAE) induced by oligodendrocyte glycoprotein peptide 35-55 (MOG35-55). The mice were injected intraperitoneally with FLaAN/C after the onset of clinical symptoms, then clinical behavior scores and changes in body weight were recorded daily. The spinal lumbar spine in model mice was enlarged and accompanied by inflammatory cell infiltration and demyelination that were reversed by FLaAN/C. FLaAN/C also induced microglia/macrophages to generate less pro-inflammatory (CD86, iNOS, and TNF-α), and more anti-inflammatory (CD206, IL-10, and Arginase-1) cytokines. These findings suggesting that FLaAN/C promoted microglial/macrophages polarization from the inflammatory M1 to the anti-inflammatory M2 phenotype. Moreover, FLaAN/C inhibited release of the inflammatory cytokines, TNF-α, IL-8, IL-6, IL-17, and IFN-γ. These results indicated that the anti-inflammatory effect of FLaAN/C was associated with the inhibited generation of reactive oxygen species. FLaAN/C downregulated the expression of phosphorylated NF-κB-p65 and prevented downstream NLRP3 inflammasome-mediated pyroptosis. Collectively, these results indicated that FLaAN/C prevents pyroptosis by inhibiting the ROS/NF-κB/NLRP3 signaling pathway, and promotes the microglial/macrophage M1/M2 polarization that significantly alleviated inflammation in mouse models of EAE. Our findings suggested that FLaAN/C could be a promising candidate for MS therapy.

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.

Andrographolide protects bone marrow mesenchymal stem cells against glucose and serum deprivation under hypoxia via the NRF2 signaling pathway

Background

Bone marrow mesenchymal stem cell (BMSCs) therapy is an important cell transplantation strategy in the regenerative medicine field. However, a severely ischemic microenvironment, such as nutrient depletion and hypoxia, causes a lower survival rate of transplanted BMSCs, limiting the application of BMSCs. Therefore, improving BMSCs viability in adverse microenvironments is an important means to improve the effectiveness of BMSCs therapy.

Objective

To illustrate the protective effect of andrographolide (AG) against glucose and serum deprivation under hypoxia (1% O₂) (GSDH)-induced cell injury in BMSCs and investigate the possible underlying mechanisms.

Methods

An in vitro primary rat BMSCs cell injury model was established by GSDH, and cellular viability, proliferation and apoptosis were observed after AG treatment under GSDH. Reactive oxygen species levels and oxidative stress-related genes and proteins were measured by flow cytometry, RT-qPCR and Western blotting. Mitochondrial morphology, function and number were further assessed by laser confocal microscopy and flow cytometry.

Results

AG protected BMSCs against GSDH-induced cell injury, as indicated by increases in cell viability and proliferation and mitochondrial number and decreases in apoptosis and oxidative stress. The metabolic status of BMSCs was changed from glycolysis to oxidative phosphorylation to increase the ATP supply. We further observed that the NRF2 pathway was activated by AG, and treatment of BMSCs with a specific NRF2 inhibitor (ML385) blocked the protective effect of AG.

Conclusion

Our results suggest that AG is a promising agent to improve the therapeutic effect of BMSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03016-6.

Focus on the Role of the NLRP3 Inflammasome in Multiple Sclerosis: Pathogenesis, Diagnosis, and Therapeutics

Neuroinflammation is initiated with an aberrant innate immune response in the central nervous system (CNS) and is involved in many neurological diseases. Inflammasomes are intracellular multiprotein complexes that can be used as platforms to induce the maturation and secretion of proinflammatory cytokines and pyroptosis, thus playing a pivotal role in neuroinflammation. Among the inflammasomes, the nucleotide-binding oligomerization domain-, leucine-rich repeat- and pyrin domain-containing 3 (NLRP3) inflammasome is well-characterized and contributes to many neurological diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), and ischemic stroke. MS is a chronic autoimmune disease of the CNS, and its hallmarks include chronic inflammation, demyelination, and neurodegeneration. Studies have demonstrated a relationship between MS and the NLRP3 inflammasome. To date, the pathogenesis of MS is not fully understood, and clinical studies on novel therapies are still underway. Here, we review the activation mechanism of the NLRP3 inflammasome, its role in MS, and therapies targeting related molecules, which may be beneficial in MS.

Targeting NLRP3 Inflammasome With Nrf2 Inducers in Central Nervous System Disorders

The NLRP3 inflammasome is an intracellular multiprotein complex that plays an essential role in the innate immune system by identifying and eliminating a plethora of endogenous and exogenous threats to the host. Upon activation of the NLRP3 complex, pro-inflammatory cytokines are processed and released. Furthermore, activation of the NLRP3 inflammasome complex can induce pyroptotic cell death, thereby propagating the inflammatory response. The aberrant activity and detrimental effects of NLRP3 inflammasome activation have been associated with cardiovascular, neurodegenerative, metabolic, and inflammatory diseases. Therefore, clinical strategies targeting the inhibition of the self-propelled NLRP3 inflammasome activation are required. The transcription factor Nrf2 regulates cellular stress response, controlling the redox equilibrium, metabolic programming, and inflammation. The Nrf2 pathway participates in anti-oxidative, cytoprotective, and anti-inflammatory activities. This prominent regulator, through pharmacologic activation, could provide a therapeutic strategy for the diseases to the etiology and pathogenesis of which NLRP3 inflammasome contributes. In this review, current knowledge on NLRP3 inflammasome activation and Nrf2 pathways is presented; the relationship between NLRP3 inflammasome signaling and Nrf2 pathway, as well as the pre/clinical use of Nrf2 activators against NLRP3 inflammasome activation in disorders of the central nervous system, are thoroughly described. Cumulative evidence points out therapeutic use of Nrf2 activators against NLRP3 inflammasome activation or diseases that NLRP3 inflammasome contributes to would be advantageous to prevent inflammatory conditions; however, the side effects of these molecules should be kept in mind before applying them to clinical practice.

Oral administration of Lactobacillus brevis 23017 combined with ellagic acid attenuates intestinal inflammatory injury caused by Eimeria infection by activating the Nrf2/HO-1 antioxidant pathway

The aim of this study was to investigate whether oral administration of Lactobacillus brevis 23017 (LB) alone and in combination with ellagic acid inhibits ChTLR15/ChNLRP3/ChIL-1β by activating the Nrf2/HO-1 pathway to attenuate intestinal inflammatory injury. Two animal experiments were performed. In Experiment 1, chickens were allocated into 7 groups: PBS, and low, medium and high dosages of live and heat-killed LB, named L/LB(+), M/LB(+) and H/LB(+), and L/LB(-), M/LB(-) and H/LB(-), respectively. In Experiment 2, chickens were divided into 5 groups: PBS, challenge control, and low, medium and high dosages of ellagic acid combined with LB(+), named L/EA + L/LB(+), M/EA + M/LB(+) and H/EA + H/LB(+), respectively. Chickens were gavaged with LB with or without ellagic acid once a day. Then, the mRNA and protein levels of the components of the Nrf2/HO-1 pathway found in the caecal tissues were quantified. On Day 7 post-infection with E. tenella, the levels of the components of the ChTLR15/NLRP3/IL-1β pathway in the caeca were again quantified, and the anticoccidial effects were assessed. The results showed that the levels of the genes in the Nrf2/HO-1 pathway in the chickens in the LB(+) groups were higher than those in the LB(-) groups (p < 0.001); those in the H/LB(+) group were higher than those in the M/LB(+) and L/LB(+) groups (p < 0.001); and those in the H/EA + H/LB(+) group showed the highest expression levels compared with the other groups (p < 0.001). After challenge, the chickens in the H/LB(+) group displayed less inflammatory injury than those in the M/LB(+) and L/LB(+) groups (p < 0.05), and the chickens in the H/EA + H/LB(+) group showed stronger anti-inflammatory effects than the other groups (p < 0.05). Thus, these protective effects against infection were consistent with the above results. Overall, significant anti-inflammatory effects were observed in chickens orally gavaged with high dosages of live L. brevis 23017 and ellagic acid, which occurred by regulation of the ChTLR15/NLRP3/IL-1β pathway.

Fruit ripening: dynamics and integrated analysis of carotenoids and anthocyanins

BACKGROUND

Fruits are vital food resources as they are loaded with bioactive compounds varying with different stages of ripening. As the fruit ripens, a dynamic color change is observed from green to yellow to red due to the biosynthesis of pigments like chlorophyll, carotenoids, and anthocyanins. Apart from making the fruit attractive and being a visual indicator of the ripening status, pigments add value to a ripened fruit by making them a source of nutraceuticals and industrial products. As the fruit matures, it undergoes biochemical changes which alter the pigment composition of fruits.

RESULTS

The synthesis, degradation and retention pathways of fruit pigments are mediated by hormonal, genetic, and environmental factors. Manipulation of the underlying regulatory mechanisms during fruit ripening suggests ways to enhance the desired pigments in fruits by biotechnological interventions. Here we report, in-depth insight into the dynamics of a pigment change in ripening and the regulatory mechanisms in action.

CONCLUSIONS

This review emphasizes the role of pigments as an asset to a ripened fruit as they augment the nutritive value, antioxidant levels and the net carbon gain of fruits; pigments are a source for fruit biofortification have tremendous industrial value along with being a tool to predict the harvest. This report will be of great utility to the harvesters, traders, consumers, and natural product divisions to extract the leading nutraceutical and industrial potential of preferred pigments biosynthesized at different fruit ripening stages.

TBHQ attenuates ferroptosis against 5-fluorouracil-induced intestinal epithelial cell injury and intestinal mucositis via activation of Nrf2

BACKGROUND

Intestinal mucositis is a common side effect of chemotherapy and radiotherapy. Very few drugs can efficiently ameliorate it. Tertiary butylhydroquinone (TBHQ) is a widely used food preservative with known immunomodulatory activity. Whether it has an effect on intestinal mucositis remains unknown. In this study, we investigated the role and mechanism of action of TBHQ on 5-fluorouracil-induced (5-FU-induced) human intestinal epithelial cell (HIEC) injury and intestinal mucositis in mice.

METHODS

We established a cell model of HIEC injury and a mouse model of intestinal mucositis via treatment with 5-FU. Cell death, Cell Counting Kit-8, and lactate dehydrogenase (LDH) release were assessed for the HIECs. Diarrhea, body weight, intestinal length, mucosal damage, and the levels of IL-6, TNF-α, IL-1β, glutathione, reactive oxygen species, and malondialdehyde were determined for the mice. Additionally, we performed immunohistochemical analysis, immunofluorescence, western blotting, quantitative real-time PCR, and ELISA to examine the effects of TBHQ. Finally, HIECs were transfected with an Nrf2 gene silencer to verify its role in ferroptosis. All data were analyzed using one-way analysis of variance or paired t-tests.

RESULTS

TBHQ markedly decreased LDH release and cell death and improved the proliferative ability of 5-FU-treated HIECs. The TBHQ-treated mice showed reduced weight loss, a lower diarrhea score, and longer colons than the 5-FU-treated mice. The in vivo expressions of IL-1β, IL-6, and TNF-α were suppressed by TBHQ treatment. Ferroptosis was shown to be involved in 5-FU-induced intestinal mucositis, and TBHQ markedly hampered its activation. Mechanistically, TBHQ activated Nrf2 effectively and selective Nrf2 knockdown significantly reduced the anti-ferroptotic functions of TBHQ in 5-FU-treated HIECs.

CONCLUSIONS

TBHQ attenuates ferroptosis in 5-FU-induced intestinal mucositis, making it a potential novel protective agent against intestinal mucositis.

Dexmedetomidine exerts cerebral protective effects against cerebral ischemic injury by promoting the polarization of M2 microglia via the Nrf2/HO-1/NLRP3 pathway

INTRODUCTION

Cerebral ischemic injury is associated with long-term disability. Dexmedetomidine (Dex) can exert neuroprotective effects on cerebral ischemic/reperfusion injury. The present study explored the mechanism of Dex in cerebral ischemic injury.

MATERIALS AND METHODS

To this end, the permanent middle cerebral artery occlusion (p-MCAO) mouse model was established and treated with Dex or/and Nrf2 inhibitor ML385. Subsequently, microglia were subjected to oxygen-glucose deprivation (OGD) in sugar-free environment and thereafter treated with Dex, Nrf2 inhibitor, and NLRP3 lentiviral overexpression vector, respectively.

RESULTS

Dex alleviated the neurobehavioral deficit of p-MCAO mice, reduced brain water content, relieved pathological changes, and reduced cerebral infarction size. Dex promoted the polarization of microglia from M1 to M2, thus ameliorating oxidative stress and inflammatory responses. Our results showed that Dex promoted M2-polarization of microglia in vivo and in vitro by promoting HO-1 expression via Nrf2 nuclear import. Moreover, the Nrf2/HO-1 axis inhibited the activation of NLRP2 inflammasome and NLRP3 overexpression reversed the effect of Dex.

CONCLUSION

In conclusion, Dex promoted M2-polarization of microglia and attenuated oxidative stress and inflammation, and thus protected against cerebral ischemic injury by activating the Nrf2/HO-1 pathway and inhibiting NLRP3 inflammasome.

Carotenoids and Apocarotenoids in Planta: Their Role in Plant Development, Contribution to the Flavour and Aroma of Fruits and Flowers, and Their Nutraceutical Benefits

Carotenoids and apocarotenoids are diverse classes of compounds found in nature and are important natural pigments, nutraceuticals and flavour/aroma molecules. Improving the quality of crops is important for providing micronutrients to remote communities where dietary variation is often limited. Carotenoids have also been shown to have a significant impact on a number of human diseases, improving the survival rates of some cancers and slowing the progression of neurological illnesses. Furthermore, carotenoid-derived compounds can impact the flavour and aroma of crops and vegetables and are the origin of important developmental, as well as plant resistance compounds required for defence. In this review, we discuss the current research being undertaken to increase carotenoid content in plants and research the benefits to human health and the role of carotenoid derived volatiles on flavour and aroma of fruits and vegetables.

Bixin protects mice against bronchial asthma though modulating PI3K/Akt pathway

Accumulating evidence has implicated the potential of natural compounds in treatment of asthma. Bixin is a natural food coloring isolated from the seeds of Bixa Orellana, which possesses anti-tumor, anti-inflammatory and antioxidative properties. Nevertheless, its therapeutic effect in asthma has not been elucidated. Our present study demonstrated that administration of Bixin suppressed allergic airway inflammation and reversed glucocorticoids resistance, as well as alleviated airway remodeling and airway hyperresponsiveness (AHR) in asthmatic mice. In vitro studies showed that Bixin treatment could inhibit the development of epithelial-mesenchymal transition (EMT) mediated by transforming growth factor beta (TGF-β) signaling. Importantly, Bixin antagonized activation of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway both in vitro and in vivo. Above all, our findings reveal that Bixin functions as a potent antagonist of PI3K/Akt signaling to protect against allergic asthma, highlighting a novel strategy for asthma treatment based on natural products.

BTN2A2 protein negatively regulates T cells to ameliorate collagen-induced arthritis in mice

Rheumatoid arthritis (RA) is an autoimmune disorder characterized by persistent inflammatory responses in target tissues and organs, resulting in the destruction of joints. Collagen type II (CII)-induced arthritis (CIA) is the most used animal model for human RA. Although BTN2A2 protein has been previously shown to inhibit T cell functions in vitro, its effect on autoimmune arthritis has not been reported. In this study, we investigate the ability of a recombinant BTN2A2-IgG2a Fc (BTN2A2-Ig) fusion protein to treat CIA. We show here that administration of BTN2A2-Ig attenuates established CIA, as compared with control Ig protein treatment. This is associated with reduced activation, proliferation and Th1/Th17 cytokine production of T cells in BTN2A2-Ig-treated CIA mice. BTN2A2-Ig also inhibits CII-specific T cell proliferation and Th1/Th17 cytokine production. Although the percentage of effector T cells is decreased in BTN2A2-Ig-treated CIA mice, the proportions of naive T cells and regulatory T cells is increased. Furthermore, BTN2A2-Ig reduces the percentage of proinflammatory M1 macrophages but increases the percentage of anti-inflammatory M2 macrophages in the CIA mice. Our results suggest that BTN2A2-Ig protein has the potential to be used in the treatment of collagen-induced arthritis models.

Bixin attenuates mechanical allodynia, anxious and depressive-like behaviors associated with experimental diabetes counteracting oxidative stress and glycated hemoglobin

Neuropathic pain, depression, and anxiety are common comorbidities in diabetic patients, whose pathophysiology involves hyperglycemia-induced increased oxidative stress. Bixin (BIX), an apocarotenoid extracted from the seeds of Bixa orellana, has been used in traditional medicine to treat diabetes and has been recognized by its antioxidant profile. We aimed to investigate the effect of the BIX over the mechanical allodynia, depressive, and anxious-like behaviors associated with experimental diabetes, along with its involved mechanisms. Streptozotocin-induced diabetic rats were treated for 17 days (starting 14 days after diabetes induction) with the corresponding vehicle, BIX (10, 30 or 90 mg/kg; p.o), or INS (6 IU; s.c.). Mechanical allodynia, depressive, and anxious-like behavior were assessed by electronic Von Frey, forced swimming, and elevated plus-maze tests, respectively. Locomotor activity was assessed by the open field test. Blood glycated hemoglobin (HbA1) and the levels of lipid peroxidation (LPO) and reduced glutathione (GSH) were evaluated on the hippocampus, pre-frontal cortex, lumbar spinal cord, and sciatic nerve. Diabetic animals developed mechanical allodynia, depressive and anxious-like behavior, increased plasma HbA1, increased LPO, and decreased GSH levels in tissues analyzed. Repeated BIX-treatment (at all tested doses) significantly attenuated mechanical allodynia, the depressive (30 and 90 mg/kg) and, anxious-like behaviors (all doses) in diabetic rats, without changing the locomotor performance. BIX (at all tested doses) restored the oxidative parameters in tissues analyzed and reduced the plasma HbA1. Thereby, bixin may represent an alternative for the treatment of comorbidities associated with diabetes, counteracting oxidative stress and plasma HbA1.