Nrf2 Activation and NF-Kb & caspase/bax signaling inhibition by sodium butyrate alleviates LPS-induced cell injury in bovine mammary epithelial cells

Biological role of mitochondrial TLR4-mediated NF-κB signaling pathway in central nervous system injury

Previous studies suggested that central nervous system injury is often accompanied by the activation of Toll-like receptor 4/NF-κB pathway, which leads to the upregulation of proapoptotic gene expression, causes mitochondrial oxidative stress, and further aggravates the inflammatory response to induce cell apoptosis. Subsequent studies have shown that NF-κB and IκBα can directly act on mitochondria. Therefore, elucidation of the specific mechanisms of NF-κB and IκBα in mitochondria may help to discover new therapeutic targets for central nervous system injury. Recent studies have suggested that NF-κB (especially RelA) in mitochondria can inhibit mitochondrial respiration or DNA expression, leading to mitochondrial dysfunction. IκBα silencing will cause reactive oxygen species storm and initiate the mitochondrial apoptosis pathway. Other research results suggest that RelA can regulate mitochondrial respiration and energy metabolism balance by interacting with p53 and STAT3, thus initiating the mitochondrial protection mechanism. IκBα can also inhibit apoptosis in mitochondria by interacting with VDAC1 and other molecules. Regulating the biological role of NF-κB signaling pathway in mitochondria by targeting key proteins such as p53, STAT3, and VDAC1 may help maintain the balance of mitochondrial respiration and energy metabolism, thereby protecting nerve cells and reducing inflammatory storms and death caused by ischemia and hypoxia.

Involvement of GPR43 Receptor in Effect of Lacticaseibacillus rhamnosus on Murine Steroid Resistant Chronic Obstructive Pulmonary Disease: Relevance to Pro-Inflammatory Mediators and Oxidative Stress in Human Macrophages

BACKGROUND

Cytokine storm and oxidative stress are present in chronic obstructive pulmonary disease (COPD). Individuals with COPD present high levels of NF-κB-associated cytokines and pro-oxidant agents as well as low levels of Nrf2-associated antioxidants. This condition creates a steroid-resistant inflammatory microenvironment. Lacticaseibacillus rhamnosus (Lr) is a known anti-cytokine in lung diseases; however, the effect of Lr on lung inflammation and oxidative stress in steroid-resistant COPD mice remains unknown.

OBJECTIVE

Thus, we investigated the Lr effect on lung inflammation and oxidative stress in mice and macrophages exposed to cigarette smoke extract (CSE) and unresponsive to steroids.

METHODS

Mice and macrophages received dexamethasone or GLPG-094 (a GPR43 inhibitor), and only the macrophages received butyrate (but), all treatments being given before CSE. Lung inflammation was evaluated from the leukocyte population, airway remodeling, cytokines, and NF-κB. Oxidative stress disturbance was measured from ROS, 8-isoprostane, NADPH oxidase, TBARS, SOD, catalase, HO-1, and Nrf2.

RESULTS

Lr attenuated cellularity, mucus, collagen, cytokines, ROS, 8-isoprostane, NADPH oxidase, and TBARS. Otherwise, SOD, catalase, HO-1, and Nrf2 were upregulated in Lr-treated COPD mice. Anti-cytokine and antioxidant effects of butyrate also occurred in CSE-exposed macrophages. GLPG-094 rendered Lr and butyrate less effective.

CONCLUSIONS

Lr attenuates lung inflammation and oxidative stress in COPD mice, suggesting the presence of a GPR43 receptor-dependent mechanism also found in macrophages.

Impact of Bacillus licheniformis-Fermented Products on Growth and Productivity in Heat-Stressed Laying Ducks

The purpose of this study was to assess the impact of various concentrations of Bacillus licheniformis-fermented products (BLFP) on the growth and productivity of laying ducks (Anas platyrhynchos) subjected to heat stress during eight weeks of a feeding trial. A total of 150 one-day-old Brown Tsaiya ducks of both sexes were divided into five groups, with each group having three replicates and 10 ducks each for evaluation of growth performance. The treatment groups received dietary supplements of BLFP at levels of 0.1%, 0.2%, and 0.3%, along with a group receiving flavomycin (F) at 5 ppm, all over a 24-week period. The fermentation process in this study utilized a B. licheniformis strain (ATCC 12713) for the production of the spores through solid-state fermentation. The control group was given a basal diet consisting of yellow corn and soybean meal. The results showed that as compared to the flavomycin group, ducks in the 0.3% BLFP group had significantly higher body weights and better feed conversion rates. In addition, during the three weeks, the BLFP group showed higher feed consumption as compared to the control group. The jejunum villi length was significantly increased in the 0.2% BLPF group as compared to the control and flavomycin groups. This study also found that the flavomycin group had a significantly higher egg conversion rate, while the 0.1-0.3% BLFP groups had improved feed intake and the 0.3% group had significantly enhanced egg yolk color. Additionally, the 0.2% BLFP group showed substantial decreases in IL-1β, TNF-α, IL-6, and IL-10 levels in the liver as well as an uptick in the tight junction protein Occludin gene expression in the colon when compared to the control group. Furthermore, the expression of the heat shock protein 70 in the gut upregulated in the 0.1% and 0.2% BLFP groups. In conclusion, these observations demonstrate that dietary supplementation of 0.2% BLFP is an ideal concentration to increase gut morphology, alleviate inflammatory response, and promote gut integrity in heat-stressed laying ducks.

Lipopolysaccharide delivery systems in innate immunity

Lipopolysaccharide (LPS), a key component of the outer membrane in Gram-negative bacteria (GNB), is widely recognized for its crucial role in mammalian innate immunity and its link to mortality in intensive care units. While its recognition via the Toll-like receptor (TLR)-4 receptor on cell membranes is well established, the activation of the cytosolic receptor caspase-11 by LPS is now known to lead to inflammasome activation and subsequent induction of pyroptosis. Nevertheless, a fundamental question persists regarding the mechanism by which LPS enters host cells. Recent investigations have identified at least four primary pathways that can facilitate this process: bacterial outer membrane vesicles (OMVs); the spike (S) protein of SARS-CoV-2; host-secreted proteins; and host extracellular vesicles (EVs). These delivery systems provide new avenues for therapeutic interventions against sepsis and infectious diseases.

Effects of Glycine Supplementation in Drinking Water on the Growth Performance, Intestinal Development, and Genes Expression in the Jejunum of Chicks

Glycine, the most basic amino acid found in nature, is considered an essential amino acid for chicks. However, the precise understanding of high concentrations of glycine's significance in promoting the growth performance of chicks, as well as its impact on intestinal development, re-mains limited. Consequently, the objective of this study was to investigate the effects of glycine supplementation in drinking water on growth performance, intestine morphology, and development in newly hatched chicks. In this study, 200 newly born chicks were selected and pro-vided with a supplementation of 0.5%, 1%, and 2% glycine in their drinking water during their first week of life. The results revealed that glycine supplementation in drinking water could significantly increase the average daily gain of chicks from days 7 to 14. Furthermore, a significant difference was observed between the group supplemented with 1% glycine and the control group. Concurrently, this glycine supplementation increased the villus height and the ratio of the villus height to crypt depth in jejunum on both day 7 and day 14. Glycine supplementation in drinking water significantly affected the mRNA expression level of the ZO-1, GCLM, and rBAT genes in jejunum, which may have certain effects on the mucosal immune defense, cellular antioxidant stress capacity, and amino acid absorption. Overall, the findings of this study indicate that glycine supplementation in drinking water can enhance the growth performance of chicks and promote their intestine development.

MicroRNA miR-223 modulates NLRP3 and Keap1, mitigating lipopolysaccharide-induced inflammation and oxidative stress in bovine mammary epithelial cells and murine mammary glands

Bovine mastitis, the most prevalent and costly disease in dairy cows worldwide, decreases milk quality and quantity, and increases cow culling. However, involvement of microRNAs (miRNAs) in mastitis is not well characterized. The objective was to determine the role of microRNA-223 (miR-223) in regulation of the nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome and kelch like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) oxidative stress pathway in mastitis models induced by lipopolysaccharide (LPS) treatment of immortalized bovine mammary epithelial cells (bMECs) and murine mammary glands. In bMECs cultured in vitro, LPS-induced inflammation downregulated bta-miR-223; the latter interacted directly with the 3' untranslated region (3' UTR) of NLRP3 and Keap1. Overexpression of bta-miR-223 in bMECs decreased LPS and Adenosine 5'-triphosphate (ATP)-induced NLRP3 and its mediation of caspase 1 and IL-1β, and inhibited LPS-induced Keap1 and Nrf2 mediated oxidative stress, whereas inhibition of bta-miR-223 had opposite effects. In an in vivo murine model of LPS-induced mastitis, increased miR-223 mitigated pathology in the murine mammary gland, whereas decreased miR-223 increased inflammatory changes and oxidative stress. In conclusion, bta-miR-223 mitigated inflammation and oxidative injury by downregulating the NLRP3 inflammasome and Keap1/Nrf2 signaling pathway. This study implicated bta-miR-223 in regulation of inflammatory responses, with potential as a novel target for treating bovine mastitis and other diseases.

Mitochondrial Calcium Uniporter Regulator 1 (MCUR1) Relieves Mitochondrial Damage Induced by Lipopolysaccharide by Mediating Mitochondrial Ca2+ Homeostasis in Bovine Mammary Epithelial Cells

The metabolic stress triggered by negative energy balance after calving induces mitochondrial damage of bovine mammary epithelial cells. Mitochondrial calcium uniporter regulator 1 (MCUR1) is a key protein-coding gene that mediates mitochondrial calcium ion (Ca²⁺) uptake and plays an important role in mediating homeostasis of mitochondria. The aim of the present study was to elucidate the effects of MCUR1-mediated Ca²⁺ homeostasis on mitochondria of bovine mammary epithelial cells in response to an inflammatory challenge with lipopolysaccharide (LPS). Exogenous LPS resulted in upregulation of the MCUR1 mRNA and protein abundance, mitochondrial Ca²⁺ content, and mitochondrial reactive oxygen species (Mito-ROS) content while decreasing mitochondrial membrane potential, causing mitochondrial damage, and increasing the rate of apoptosis. Ryanodine pretreatment attenuated the upregulation of the mitochondrial Ca²⁺ content and Mito-ROS content induced by LPS. Overexpression of MCUR1 increased the mitochondrial Ca²⁺ content and Mito-ROS content, while it decreased mitochondrial membrane potential, damaged mitochondria, and induced cell apoptosis. In addition, knockdown of MCUR1 by small interfering RNA attenuated LPS-induced mitochondrial dysfunction by inhibiting mitochondrial Ca²⁺ uptake. Our results revealed that exogenous LPS induces MCUR1-mediated mitochondrial Ca²⁺ overload in bovine mammary epithelial cells, which leads to mitochondrial injury. Thus, MCUR1-mediated Ca²⁺ homeostasis may be a potential therapeutic target against mitochondrial damage induced by metabolic challenges in bovine mammary epithelial cells.

Structural characterization and antinociceptive activity of polysaccharides from Anoectochilus elatus

Anoectochilus elatus is a new record species from Yunnan province in China discovered by our group in 2018, used in folk as the most popular Anoectochilus species A. roxburghii for medicinal and culinary purposes. The crude polysaccharide of Anoectochilus elatus (AEP) exhibited significant antinociceptive effects against both chemical and thermal nociception in vivo. Bio-guided isolation identified GJXL-1 as the leading analgesic polysaccharide in AEP. Detailed structural analyses rationalized GJXL-1 (molecular weight: 10.3 kDa) as an α-D-1,4-linked glucan unexpectedly branched at O-3, and O-6 position. GJXL-1 dose-dependently suppressed acetic acid-induced writhing in mice and decreased the serum levels of NO, IL-6 and TNF-α, which also repressed the licking times in both the first and second phases in formalin test. Furthermore, only L-nitroarginine partly reversed the analgesic activity of GJXL-1, indicating that GJXL-1's efficacy was partially mediated by NO regulation, possibly through inhibiting IRAK4/TAK1/NF-κB signaling pathway, and modulating gut microbiota and short-chain fatty acids production. In addition, the motor impairment and hypnotic effects of GJXL-1 were excluded. Our study suggests that GJXL-1 can be regarded as a promising and safe drug candidate for diverse pain disorders, and also a promising prebiotic candidate to maintain intestinal homeostasis and promote human gut health.

Extraction Optimization and Antioxidant Activities of Ethanol Extract of the Brown Roll-Rim Mushroom Paxillus involutus (Agaricomycetes)

Box Behnken design (BBD) was used to optimize the extraction of Paxillus involutus (EPI) in ethanol. The optimum extraction conditions were as follows: temperature 45°C; solid:liquid ratio 1:35; time 5 h. Under these conditions, the yield of EPI was 13.57%. The antioxidant activity of EPI was evaluated in vitro, and DPPH free radical scavenging, ABTS free radical scavenging, and hydroxyl free radical scavenging effects were found to be equal to or close to that of the positive control vitamin C (VC). The antioxidant activity of EPI was next evaluated in vivo using aging mice; it was found to have appreciable effect on scavenging malonic dialdehyde (MDA) and could increase the activity of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT), and total superoxide dismutase (T-SOD) in mice. Overall, EPI showed antioxidant effects in aging mice, thereby delaying aging, and has potential for application as a natural antioxidant and in medical applications.

MiR-342-5p protects neurons from cerebral ischemia induced-apoptosis through regulation of Akt/NF-κB pathways by targeting CCAR2

OBJECTIVES

Ischemic stroke causes high morbidity, mortality and health burden in the world. MiR-342-5p was associated with Alzheimer's disease and cardio-protection. Herein, we aimed to reveal effects of miR-342-5p on cerebral ischemia injury as well as novel targets for stroke.

MATERIALS AND METHODS

AgomiR-342-5p was intracerebroventricularly injected into the middle cerebral artery occlusion (MCAO) mouse models to evaluate functions of miR-342-5p on cerebral ischemia. RT-qPCR and western blot assays were used to evaluate genes expression. Oxygen-glucose deprivation (OGD) was used as an in vitro model for ischemia. Viability and apoptosis ratio of neurons was evaluated by CCK-8, LDH release detection, and flow cytometry. The potential targets of miR-342-5p were predicted by Targetscan, and their interaction was confirmed by luciferase assay.

RESULTS

The intervention of miR-342-5p effectively attenuated ischemic injury in MCAO mice. MiR-342-5p overexpression could protect neurons against OGD-induced injury, as revealed by increased cell viability and BCL2 expression, and decreased LDH release, apoptosis ratio, and BAX expression in OGD-induced neurons. Mechanically, miR-342-5p could directly bound with CCAR2 to inhibit its expression. Overexpressing CARR2 aggravated the OGD-induced injury of neurons, which was partly restrained by overexpressing miR-342-5p reversed. Furthermore, miR-342-5p/CARR2 axis regulates Akt/NF-κB signaling pathway in vitro as well as in vivo cerebral ischemia models.

CONCLUSIONS

MiR-342-5p inhibited neuron apoptosis by regulating Akt/NF-kB signaling pathway via CCAR2 suppression. Our findings revealed the neuroprotection of miR-342-5p in cerebral ischemia.

Nrf2 orchestrates transition from acute to chronic otitis media through inflammatory macrophages

Introduction

Acute and chronic otitis media (AOM and COM) are common middle ear infections that can lead to hearing loss and other complications. Recent research has shown that both macrophages and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway are involved in the immune response to and the resolution of otitis media. However, the specific effects of Nrf2 on macrophages in the transition of AOM to COM are not well understood, and a practical approach to prevent this transition by targeting Nrf2/macrophages has not been established.

Methods

In an AOM mouse model using lipopolysaccharide (LPS) injection into the middle ear, middle ear effusion (OME)-macrophages were isolated and analyzed for Nrf2 expression. M2-like polarization of macrophages was induced by Nrf2 activation and its effects on inflammatory resolution were studied by examining inflammatory neutrophils and macrophages, proinflammatory cytokines, and oxidative levels. The survival of human middle ear epithelial cells (HMMECs) co-cultured with Nrf2-modified macrophages was also evaluated. Furthermore, restoration of Nrf2 in macrophages with adeno-associated virus (AAV) vectors was performed to determine the effect on the transition of AOM to COM in experimental mice.

Results

Reduced Nrf2 in OME-macrophages during the recovery phase was associated with uncured AOM or its development into COM, demonstrated by persistent increases in inflammatory neutrophils and macrophages, proinflammatory cytokines, and oxidative levels. Nrf2 activation induced M2-like polarization of macrophages, which improved the survival of co-cultured HMMECs treated with LPS in vitro. Restoration of Nrf2 in OME-derived low-Nrf2-expressing macrophages with AAV vectors significantly inhibited the transition of AOM to COM in experimental mice.

Discussion

Nrf2 in macrophages plays a critical role in the immune response to and resolution of otitis media Restoration of Nrf2 expression in OME-macrophages could be a promising therapeutic approach to prevent the development of COM in AOM patients.

Cadmium exposure promotes thyroid pyroptosis and endocrine dysfunction by inhibiting Nrf2/Keap1 signaling

Cadmium (Cd) is a ubiquitous toxic metal and environmental pollutant. Increasing studies have shown that Cd exposure increases the incidence of various endocrine system diseases, including thyrotoxicity reflected by thyroid structural damage and endocrine toxicity. However, the observed outcomes are complex and conflicting, leading to the mechanism of Cd-induced thyrotoxicity remaining obscure. In this study, 4-week-old male C57BL/6 mice were given 2 or 7 mg/kg Cadmium Chloride (CdCl₂) intragastrically for 4 and 8 weeks, and the Cd-mediated thyrotoxicity was evaluated by determining alterations in thyroid structure and endocrine function, and alterations of oxidant stress, apoptosis, and pyroptosis. Our data showed that Cd exposure could reduce body weight and induce thyrotoxicity by impairing thyroid follicular morphology and endocrine function, accompanied by elevated oxidative stress and apoptosis, macrophage infiltration, and inflammatory cytokine secretion. Importantly, Cd significantly promoted thyroid follicular cell pyroptosis by increasing Nlrp3, Asc, Caspase-1, Gsdmd, IL-1β, and IL-18 expression. Mechanistical analysis suggested that Cd treatment could inhibit antioxidant pathway by downregulating antioxidant response protein, Nrf2, and upregulating its negative feedback regulator, Keap1. Collectively, our in vivo findings suggest that Cd exposure could facilitate thyroid follicular cell pyroptosis by inhibiting Nrf2/Keap1 signaling, thereby disrupting thyroid tissue structure and endocrine function, which offers novel insights into the Cd-mediated detrimental consequences on thyroid homeostasis.

Dietary glycine supplementation prevents heat stress-induced impairment of antioxidant status and intestinal barrier function in broilers

This study tested the hypothesis that glycine improves intestinal barrier function through regulating oxidative stress in broilers exposed to heat stress. A total of 300 twenty-one-day-old female Arbor Acres broilers (600 ± 2.5g) was randomly allocated to 5 treatments (6 replicate of 10 birds each). The 5 treatments were as follows: the control group (CON) was kept under thermoneutral condition (24 ± 1°C) and was fed a basal diet. Broilers fed a basal diet and reared under high ambient temperature (HT) were considered as the HT group (34 ± 1°C for 8 h/d). Broilers fed a basal diet supplemented with 0.5%, 1.0%, and 2.0% glycine and exposed to HT were regarded as the HT + glycine treatments. The results exhibited that heat stress reduced growth performance, serum total antioxidant capacity (T-AOC), and glutathione (GSH) concentration (P < 0.05); increased activity of serum catalase (CAT) and the contents of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) (P < 0.05). HT exposure led to downregulating the mRNA expression of NAD(P)H quinone dehydrogenase 1 (NQO1), Occludin, and zonula occludens-1 (ZO-1) (P < 0.05); enhanced the mRNA levels of Kelch-like ECH-associated protein 1 (Keap1), CAT, glutathione synthetase (GSS), and glutamate-cysteine ligase modifier subunit (GCLM) (P < 0.05); impaired the intestinal morphology (P < 0.05); and altered the diversity and community of gut microbiota (P < 0.05). The final body weight (FBW), ADFI, ADG, and gain-to-feed ratio (G: F) increased linearly or quadratically, and the antioxidant capacity was improved (P < 0.05) with glycine supplementation. Glycine treatment increased the villus height (VH), and villus height to crypt depth ratio (V/C) of the duodenum linearly or quadratically, and linearly increased the VH of jejunum and ileum. The mRNA expression of Occludin, and ZO-1 were increased linearly in the ileum mucosa of broilers subjected to HT. Collectively, these results demonstrated that glycine supplementation alleviates heat stress-induced dysfunction of antioxidant status and intestinal barrier in broilers.

Proof-of-Principle Study Suggesting Potential Anti-Inflammatory Activity of Butyrate and Propionate in Periodontal Cells

Short-chain fatty acids (SCFAs) are potent immune modulators present in the gingival crevicular fluid. It is therefore likely that SCFAs exert a role in periodontal health and disease. To better understand how SCFAs can module inflammation, we screened acetic acid, propionic acid, and butyric acid for their potential ability to lower the inflammatory response of macrophages, gingival fibroblasts, and oral epithelial cells in vitro. To this end, RAW 264.7 and primary macrophages were exposed to LPSs from Porphyromonas gingivalis (P. gingivalis) with and without the SCFAs. Moreover, gingival fibroblasts and HSC2 oral epithelial cells were exposed to IL1β and TNFα with and without the SCFAs. We report here that butyrate was effective in reducing the lipopolysaccharide (LPS)-induced expression of IL6 and chemokine (C-X-C motif) ligand 2 (CXCL2) in the RAW 264.7 and primary macrophages. Butyrate also reduced the IL1β and TNFα-induced expression of IL8, chemokine (C-X-C motif) ligand 1 (CXCL1), and CXCL2 in gingival fibroblasts. Likewise, butyrate lowered the induced expression of CXCL1 and CXCL2, but not IL8, in HSC2 cells. Butyrate further caused a reduction of p65 nuclear translocation in RAW 264.7 macrophages, gingival fibroblasts, and HSC2 cells. Propionate and acetate partially lowered the inflammatory response in vitro but did not reach the level of significance. These findings suggest that not only macrophages, but also gingival fibroblasts and oral epithelial cells are susceptive to the anti-inflammatory activity of butyrate.