Selenium Alleviates Inflammation in Staphylococcus aureus-Induced Mastitis via MerTK-Dependent Activation of the PI3K/Akt/mTOR Pathway in Mice

Transcriptome analysis reveals the regulation of miR-19b on inflammation in bovine mammary epithelial cells

MicroRNAs (miRNAs) are involved in various biological processes where they regulate the expression of mRNAs. Bovine mammary epithelial cells (bMECs) are functional cells that mediate mammary inflammatory immunity. Although numerous miRNAs regulate the function of bMECs, the role of miR-19b in bMECs has not been reported. In this study, the transcriptome of miR-19b overexpressed bMECs was analyzed by RNA-seq. Additionally, the differentially expressed genes (DEGs) were analyzed to establish the role of miR-19b in bMECs. The results revealed 269 DEGs between the miR-19b overexpression group and the negative control, including 199 up-regulated and 70 down-regulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that the DEGs regulated immune and inflammatory responses through Staphylococcus aureus (S. aureus) infection and phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. In addition, the expression of miR-19b was significantly upregulated in lipophosphoric acid (LTA)-induced bMECs, and overexpression of miR-19b negatively regulated the expression of inflammatory cytokines IL-1β and IL-6, thereby alleviating the inflammatory response of LTA-induced bMECs. Based on the above results, we speculate that miR-19b may inhibit in dairy cow mammary inflammation caused by S. aureus, and this process may be mediated through the regulation of relevant gene expression and signaling pathways. The findings from this study provide a new reference for analyzing the molecular regulation of miR-19b in bMECs.

N6-methyladenosine-modified lncRNA in Staphylococcus aureus-injured bovine mammary epithelial cells

Staphylococcus aureus-induced mastitis is a serious disease in dairy bovine, with no currently effective treatment. Antibiotics demonstrate certain therapeutic potency in dairy husbandry; they generate drug-resistant bacteria, thereby harming public health. LncRNAs and m6A have been verified as potential targets in infectious diseases and have powerful regulatory capabilities. However, the biological regulation of lncRNAs with m6A modification in mastitis needs further investigation. This study aims to determine the m6A-modified lncRNAs in bovine mammary epithelial cells and their diversity during S. aureus induction. Heat-inactivated S. aureus was used to develop the cell injury model, and we subsequently found low cell viability and different m6A modification levels. Our analysis of m6A-modified lncRNA profiles through MeRIP-seq revealed significant differences in 140 peaks within 130 lncRNAs when cells were injured by S. aureus. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that these differential m6A-modified lncRNAs were mainly enriched in the WNT pathway, and their functions were associated with amino acid metabolism, lipid translocation, and metalloproteinase activity. Here, we report for the first time lncRNAs with m6A modification in regulating S. aureus infection, revealing potential mechanisms and targets of infectious diseases, such as mastitis, from an epigenetics perspective.

HuoXueTongFu formula induces M2c macrophages via the MerTK/PI3K/AKT pathway to eliminate NETs in intraperitoneal adhesion in mice

ETHNOPHARMACOLOGICAL RELEVANCE

HuoXueTongFu Formula (HXTF) is a traditional Chinese herbal formula that has been used as a supplement and alternative therapy for intraperitoneal adhesion (IA). However, its specific mechanism of action has not been fully understood.

AIM OF THE STUDY

In surgery, IA presents an inevitable challenge, significantly impacting patients' physical and mental well-being and increasing the financial burden. Our previous research has confirmed the preventive effects of HXTF on IA formation. However, the precise mechanism of its action still needs to be understood.

METHODS

In this study, the IA model was successfully established by using the Ischemic buttons and treated with HXTF for one week with or without Mer Tyrosine Kinase (MerTK) inhibitor. We evaluated the pharmacodynamic effect of HXTF on IA mice. The MerTK/phosphoinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway-associated proteins were detected by Western blotting. Neutrophil extracellular traps (NETs) were detected by immunofluorescence. Macrophage phenotype was assessed by immunohistochemistry and flow cytometry. Inflammatory cytokines were detected by Real Time Quantitative PCR and Western blotting.

RESULTS

HXTF reduced inflammatory response and alleviated IA. HXTF significantly enhanced MerTK expression, increased the number of M2c macrophages, and decreased the formation of NETs. In addition, the MerTK/PI3K/AKT pathway was significantly activated by HXTF. However, after using MerTK inhibitors, the role of HXTF in inducing M2c macrophage through activation of the PI3K/AKT pathway was suppressed and there was no inhibitory effect on NETs formation and inflammatory responses, resulting in diminished inhibition of adhesion.

CONCLUSION

HXTF may improve IA by activating the MerTK/PI3K/AKT pathway to induce M2c polarization, which removes excess NETs and attenuates the inflammatory response.

Enhancing bovine immune, antioxidant and anti-inflammatory responses with vitamins, rumen-protected amino acids, and trace minerals to prevent periparturient mastitis

Mastitis, the inflammatory condition of mammary glands, has been closely associated with immune suppression and imbalances between antioxidants and free radicals in cattle. During the periparturient period, dairy cows experience negative energy balance (NEB) due to metabolic stress, leading to elevated oxidative stress and compromised immunity. The resulting abnormal regulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS), along with increased non-esterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) are the key factors associated with suppressed immunity thereby increases susceptibility of dairy cattle to infections, including mastitis. Metabolic diseases such as ketosis and hypocalcemia indirectly contribute to mastitis vulnerability, exacerbated by compromised immune function and exposure to physical injuries. Oxidative stress, arising from disrupted balance between ROS generation and antioxidant availability during pregnancy and calving, further contributes to mastitis susceptibility. Metabolic stress, marked by excessive lipid mobilization, exacerbates immune depression and oxidative stress. These factors collectively compromise animal health, productive efficiency, and udder health during periparturient phases. Numerous studies have investigated nutrition-based strategies to counter these challenges. Specifically, amino acids, trace minerals, and vitamins have emerged as crucial contributors to udder health. This review comprehensively examines their roles in promoting udder health during the periparturient phase. Trace minerals like copper, selenium, and calcium, as well as vitamins; have demonstrated significant impacts on immune regulation and antioxidant defense. Vitamin B12 and vitamin E have shown promise in improving metabolic function and reducing oxidative stress followed by enhanced immunity. Additionally, amino acids play a pivotal role in maintaining cellular oxidative balance through their involvement in vital biosynthesis pathways. In conclusion, addressing periparturient mastitis requires a holistic understanding of the interplay between metabolic stress, immune regulation, and oxidative balance. The supplementation of essential amino acids, trace minerals, and vitamins emerges as a promising avenue to enhance udder health and overall productivity during this critical phase. This comprehensive review underscores the potential of nutritional interventions in mitigating periparturient bovine mastitis and lays the foundation for future research in this domain.

Nano-selenium Antagonizes Heat Stress-Induced Apoptosis of Rainbow Trout (Oncorhynchus mykiss) Hepatocytes by Activating the PI3K/AKT Pathway

The cold-water fish rainbow trout (Oncorhynchus mykiss) shows poor resistance to heat, which is the main factor restricting their survival and yield. With the advancement of nanotechnology, nano-selenium (nano-Se) has emerged as a key nano-trace element, showing unique advantages, including high biological activity and low toxicity, for studying the response of animals to adverse environmental conditions. However, little is still known regarding the potential protective mechanisms of nano-Se against heat stress-induced cellular damage. Herein, we aimed to investigate the mechanism underlying the antagonistic effects of nano-Se on heat stress. Four groups were assessed: CG18 (0 μg/mL nano-Se, 18 °C), Se18 (5.0 μg/mL nano-Se, 18 °C), CG24 (0 μg/mL nano-Se, incubated at 18 °C for 24 h and then transferred to 24 °C culture), and Se24 (5.0 μg/mL nano-Se, incubated at 18 °C for 24 h and then transferred to 24 °C culture). We found that after heat treatment (CG24 group), T-AOC, GPx, and CAT activities in rainbow trout hepatocytes showed a decrease of 36%, 33%, and 19%, respectively, while ROS and MDA levels showed an increase of 67% and 93%, respectively (P < 0.05). Meanwhile, the mRNA levels of the apoptosis-related genes caspase3, caspase9, Cyt-c, Bax, and Bax/Bcl-2 in the CG24 group were 41%, 47%, 285%, 65%, and 151% higher than those in the CG18 group, respectively, while those of PI3K and AKT were 31% and 17% lower, respectively (P < 0.05). Besides, flow cytometry analysis showed an increase in the level of apoptotic cells after heat exposure. More importantly, we observed that nano-Se cotreatment (Se24 group) remarkably attenuated heat stress-induced effects (P < 0.05). We conclude that heat stress induces oxidative stress and apoptosis in rainbow trout hepatocytes. Nano-Se ameliorates heat stress-induced apoptosis by activating the PI3K/AKT pathway. Our results provide a new perspective to improve our understanding of the ability of nano-Se to confer heat stress resistance.

The Role of N6-Methyladenosine in Inflammatory Diseases

N⁶-Methyladenosine (m⁶A) is the most abundant epigenetic RNA modification in eukaryotes, regulating RNA metabolism (export, stability, translation, and decay) in cells through changes in the activity of writers, erasers, and readers and ultimately affecting human life or disease processes. Inflammation is a response to infection and injury in various diseases and has therefore attracted significant attention. Currently, extensive evidence indicates that m⁶A plays an essential role in inflammation. In this review, we focus on the mechanisms of m⁶A in inflammatory autoimmune diseases, metabolic disorder, cardio-cerebrovascular diseases, cancer, and pathogen-induced inflammation, as well as its possible role as targets for clinical diagnosis and treatment.

Selenium Deficiency Induces Apoptosis, Mitochondrial Dynamic Imbalance, and Inflammatory Responses in Calf Liver

Selenium (Se) deficiency significantly impacts the cow breeding industry by reducing the milk quality of dairy cows and affecting the health of calves. The molecular mechanism of Se deficiency-induced damage to calves, however, remains unclear. The present study investigated whether Se deficiency induces oxidative stress, apoptosis, and inflammation in calf liver tissues. We collected the liver tissues of calves with Se deficiency. Experimental results showed that Se deficiency weakened the activity of antioxidant enzymes and increased the accumulation of oxidation products in the liver. Se deficiency also led to excessive fission of the mitochondria and downregulated the expression of the Mfn2 and Opa1 genes in the calf liver. Mitochondrial damage-induced apoptosis by increasing the expression of pro-apoptotic genes such as CytC, Cas3, Cas9, fas, and Cas8, leading to a decrease in energy metabolism. Se deficiency also triggered the expression of inflammatory-related factors such as IL-1β, IL-6, TNF-α, and NF-κB. Taken together, the results suggest that Se deficiency causes oxidative stress, triggers an inflammatory response, disrupts mitochondrial dynamic balance, and then induces apoptosis, eventually leading to calf liver damage. These findings might provide valuable clues for elucidating the mechanism of Se deficiency-induced injury in domestic animals.

Comprehensive proteomic analysis to elucidate the anti-heat stress effects of nano-selenium in rainbow trout (Oncorhynchus mykiss)

Because of the continuous intensification of global warming, extreme climate fluctuations, and high-density farming, cold-water rainbow trout (Oncorhynchus mykiss) are exposed to conditions of heat stress, which has severely impacted their survival and yield. Nano-selenium (nano-Se) shows higher biological activity and lower toxicity and has emerged as an ideal and ecological Se formulation. Herein rainbow trout were fed either a basal diet (control group) or basal diet plus 5 mg/kg nano-Se (treatment group). Samples were collected before (18 °C for 9 days; CG18, Se18) and after (24 °C for 8 h; CG24, Se24) heat stress. The DIA/SWATH approach was then applied to compare changes at the proteome level. We found 223 and 269 differentially abundant proteins in the CG18-CG24 and Se18-Se24 groups, respectively, which mainly included apoptosis-, heat stress-, and lipid-related proteins. In comparison with the CG18-CG24 group, the Se18-Se24 group showed higher abundance of molecular chaperone, such as Hsp70, Hsp90a.1, Hspa8, Hsp30, DNAJA4, Dnajb1, Bag2 and Ahsa1; on nano-Se supplementation, the heat stress-induced decline in the abundance of the selenoprotein MsrB2 was partially restored. Furthermore, nano-Se supplementation downregulated the abundance of lipid-related (CYP51, EBP, DHCR7, DHCR24, and APOB) and pro-apoptotic (caspase-8 and Bad) proteins. Protein-protein interaction analyses suggested that nano-Se inhibits apoptosis by upregulating the expression of Hsp70, Hsp90a.1, Hspa8, and Dnajb1; further, Hsp70/Hspa8 and MsrB2 appear to play a synergistic role in antioxidant defense under heat stress. Overall, our findings provide novel insights into nano-Se-mediated tolerance of heat stress, demonstrating that nano-Se exerts its anti-heat stress effects in rainbow trout by promoting protein repair, enhancing recovery of antioxidant enzyme activity, and alleviating lipid metabolism and apoptosis.

Selenium Attenuates Doxorubicin-Induced Cardiotoxicity Through Nrf2-NLRP3 Pathway

Selenium (Se), an essential nutrient for humans, has been reported to possess cardioprotective effect. However, the protective effects of Se against doxorubicin (DOX)-induced cardiotoxicity and the underlying mechanism are rarely reported. In this study, we sought to explore whether Se protected against DOX-induced cardiotoxicity by inhibiting Nrf2-NLRP3 pathway. We found that Se treatment effectively alleviated DOX-induced myocardial dysfunctions, decreasing plasma markers associated with myocardial injury. Moreover, Se treatment significantly inhibited DOX-induced oxidative damages and pro-inflammatory cytokine expression in heart tissues. Furthermore, Se treatment markedly promoted the expression of Nrf2 and prevented the activation of NLRP3 inflammasome. Importantly, suppression of Nrf2 abolished the cardioprotective effects of Se and diminished the inhibition of Se on NLRP3 inflammasome. Collectively, our study demonstrated that Se might protect against DOX-induced cardiotoxicity via regulating Nrf2-NLRP3 pathway. Se supplementation may be a potential therapeutic strategy to protect against DOX-induced cardiac injury.

Role of Selenium and Vitamins E and B9 in the Alleviation of Bovine Mastitis during the Periparturient Period

Mastitis (inflammation of the mammary gland) commonly occurs in dairy cattle during the periparturient period (transition period), in which dairy cattle experience physiological and hormonal changes and severe negative energy balance, followed by oxidative stress. To maintain successful lactation and combat negative energy balance (NEB), excessive fat mobilization occurs, leading to overproduction of reactive oxygen species (ROS). Excessive fat mobilization also increases the concentrations of nonesterified fatty acids (NEFA) and β-hydroxybutyric acid (BHB) during the periparturient period. In addition, the excessive utilization of oxygen by cellular respiration in the mammary causes abnormal production of oxidative stress (OS). OS impairs the immunity and anti-inflammatory efficiency of periparturient dairy cattle, increasing their susceptibility to mastitis. To alleviate oxidative stress and subsequent mastitis, antioxidants are supplemented to dairy cattle from an external source. Extensive studies have been conducted on the supplementation of selenium (Se) and vitamins E and B9 to mitigate mastitis during the transition period in dairy cattle. Altogether, in the current review, we discuss the research development on bovine mastitis and its major causes, with special emphasis on oxidative stress during the transition period. Moreover, we discuss the antioxidant, immunoregulatory, and anti-inflammatory properties of Se and vitamins E and B9 and their role in the control of bovine mastitis in periparturient dairy cattle.