Protective Effects of Lixisenatide against Lipopolysaccharide-Induced Inflammation Response in MAC-T Bovine Mammary Epithelial Cells: A Therapeutic Implication in Mastitis

Anti-inflammatory effects of apigenin on LPS-induced mastitis in lactating SD rats through inhibiting TLR4/NF-κB signaling pathway

Mastitis is an important disease of the mammary gland in all kinds of lactating mammals, endangering the development of animal husbandry and human health. Apigenin is one chemical constituent of Taraxacum and Philippine Violet Herb which are effective Chinese herbs for the treatment of mastitis. It is reported that apigenin possesses anti-inflammatory activity and other pharmacological effects. However, the attenuation of apigenin on mastitis has not yet been reported. The present study investigated the protection of apigenin against lipopolysaccharide (LPS)-induced mastitis in SD rats both in vivo and in vitro. The results suggested that apigenin relieved the lesions of mammary tissues induced by LPS, decreased mRNA and protein levels of pro-inflammatory cytokines:tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Simultaneously, apigenin reduced the increasing content of myeloperoxidase (MPO) and Toll-like receptor 4 (TLR4), and phosphorylation of nuclear factor kappa B (NF-κB) induced by LPS. The results showed that apigenin was able to attenuate the LPS-induced mastitis in rats by inhibiting the TLR4/NF-κB signaling pathway in vivo and in vitro, which provides scientific references for further research.

Protective Effects of Chitosan Oligosaccharide Against Lipopolysaccharide-Induced Inflammatory Response and Oxidative Stress in Bovine Mammary Epithelial Cells

Chitosan oligosaccharide (COS) is receiving increasing attention as a feed additive in animal production. COS has a variety of biological functions, including anti-inflammatory and antioxidant activities. Mastitis is a major disease in dairy cows that has a significant impact on animal welfare and production. Hence, this research aimed to investigate the mechanism of COS on the lipopolysaccharide (LPS)-stimulated inflammatory response and oxidative stress in bovine mammary epithelial cells (BMECs). In this study, the results demonstrated that COS protected BMECs from the inflammatory response induced by LPS by restraining the excessive production of toll-like receptor 4 (TLR4), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β). COS treatment also suppressed excessive reactive oxygen species (ROS) production and restored antioxidant enzyme activity under LPS-induced oxidative stress conditions. Furthermore, the results also demonstrated that COS promote nuclear factor erythroid 2-related factor 2 (Nrf2) expression and inhibit TLR4 levels and p65 and IκBα phosphorylation in BMECs exposed to LPS. In summary, the results demonstrate that the protective mechanism of COS on the LPS-induced inflammatory response and oxidative stress depend on the TLR4/nuclear factor-κB (NF-κB) and Nrf2 signaling pathways, indicating that COS could serve as natural protective agents for alleviating BMECs in mastitis.

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.

Lixisenatide ameliorated lipopolysaccharide (LPS)-induced expression of mucin and inflammation in bronchial epithelial cells

Chronic obstructive pulmonary disease (COPD) induces serious social and economic burdens due to its high disability and mortality, the pathogenesis of which is highly involved with inflammation, oxidative stress (OS), and mechanism of mucin 5AC (MUC5AC) secretion. Lixisenatide is a selective glucagon-like peptide 1 receptor agonist recently reported to have anti-inflammatory properties. Our study will focus on the potential impact of lixisenatide on lipopolysaccharide (LPS)-induced mucin secretion and inflammation in 16 human bronchial epithelial (16HBE) cells to check its potential function in COPD. 16HBE cells were treated with LPS, with or without lixisenatide (10 and 20 nM) for 1 day. Remarkably declined cell viability, enhanced lactate dehydrogenase release, activated OS, and elevated release of inflammatory cytokines were observed in LPS-treated 16HBE cells, accompanied by the activation of nuclear factor-κB signaling, all of which were signally reversed by lixisenatide. Moreover, elevated expression and release of MUC5AC were observed in LPS-treated 16HBE cells but were markedly repressed by lixisenatide. Furthermore, the repressed nuclear factor erythroid 2-related factor 2 (Nrf2) level in LPS-treated 16HBE cells was notably rescued by lixisenatide. Lastly, following the knockdown of Nrf2, the protective function of lixisenatide on LPS-triggered MUC5AC release in 16HBE cells was significantly abrogated. Collectively, lixisenatide ameliorated LPS-induced expression of mucin and inflammation in bronchial epithelial cells by regulating Nrf2.

Tanshinone IIa alleviates LPS-induced oxidative stress in dairy cow mammary epithelial cells by activating the Nrf2 signalling pathway

OBJECTIVE

Mastitis is the most prevalent disease in dairy cows worldwide. Evidence has emerged that oxidative stress plays a crucial role in the development of mastitis. This study aimed to investigate the antioxidative effects of tanshinone IIa (Tan IIa) on LPS-induced oxidative stress in dairy cow mammary epithelial cells (CMECs).

METHODS AND RESULTS

We examined the levels of ROS and MDA in LPS-treated CMECs after supplementation with Tan IIa using detection kits and found that Tan IIa significantly inhibited the upregulation of these factors. In addition, we also found that Tan IIa significantly reversed the decrease in mitochondrial membrane potential induced by LPS. Moreover, Tan IIa improved the activities of antioxidant enzymes, which were decreased by LPS. Finally, we examined the probable pathway in which Tan IIa exerted its antioxidant effects using qPCR and western blotting and found that Tan IIa significantly activated the Keap1/Nrf2 signalling pathway.

CONCLUSION

These results suggest that Tan IIa might become a possible therapeutic agent for the treatment of dairy cow mastitis by weakening oxidative stress induced by LPS in CMECs.

Early inflammatory events of mastitis-a pilot study with the isolated perfused bovine udder

BACKGROUND

Bovine mastitis is an important health and cost factor in the milk industry. To elucidate whether isolated perfused bovine udders can be used to study early inflammatory events of mastitis, 1 mg of lipopolysaccharide (LPS) was instilled into quarters of 10 isolated perfused bovine udders. Three hours and 6 h after LPS instillation, tissue samples were taken from the gland cistern and base of the udder, subsequently stored in RNAlater and processed for the determination of inflammation-dependent gene regulation by real-time RT-qPCR. Gene expression analysis was performed using delta-delta Ct method. To translate mRNA results to protein, IL-1ß and IL-6 were determined in tissue homogenate by ELISA.

RESULTS

The instillation of 1 mg LPS lead to an increased expression of pro-inflammatory cytokines and chemokines like TNF-α, CCL20, CXCL8 as well as of IL-1 ß, IL-6 and IL-10, lingual antimicrobial peptide (LAP) and S100A9. However, the degree of elevation differed slightly between gland cistern and udder base and markedly between 3 and 6 h after instillation, with a distinct increase in mediator expression after 6 h. IL-1β protein increased in a time-dependent manner, whereas IL-6 was unchanged within 6 h of LPS instillation.

CONCLUSION

Compared to in vivo studies with instillation of LPS into udders of living cows, a similar inflammation-dependent gene regulation profile can be mimicked in the isolated perfused bovine udder, indicating a supplementation of animal experiments.

Treatment repurposing for inflammatory bowel disease using literature-related discovery and innovation

Inflammatory bowel disease (IBD) incidence has been increasing steadily, most dramatically in the Western developed countries. Treatment often includes lifelong immunosuppressive therapy and surgery. There is a critical need to reduce the burden of IBD and to discover medical therapies with better efficacy and fewer potential side-effects. Repurposing of treatments originally studied in other diseases with similar pathogenesis is less costly and time intensive than de novo drug discovery. This study used a treatment repurposing methodology, the literature-related discovery and innovation (LRDI) text mining system, to identify potential treatments (developed for non-IBD diseases) with sufficient promise for extrapolation to treatment of IBD. By searching for desirable patterns of twenty key biomarkers relevant to IBD (e.g., inflammation, reactive oxygen species, autophagy, barrier function), the LRDI-based query retrieved approximately 9500 records from Medline. The most recent 350 records were further analyzed for proof-of-concept. Approximately 18% (64/350) met the criteria for discovery (not previously studied in IBD human or animal models) and relevance for application to IBD treatment. Many of the treatments were compounds derived from herbal remedies, and the majority of treatments were being studied in cancer, diabetes, and central nervous system disease, such as depression and dementia. As further validation of the search strategy, the query identified ten treatments that have just recently begun testing in IBD models in the last three years. Literature-related discovery and innovation text mining contains a unique search strategy with tremendous potential to identify treatments for repurposing. A more comprehensive query with additional key biomarkers would have retrieved many thousands more records, further increasing the yield of IBD treatment repurposing discovery.

Effects of Peptidoglycan, Lipoteichoic Acid and Lipopolysaccharide on Inflammation, Proliferation and Milk Fat Synthesis in Bovine Mammary Epithelial Cells

The mammary gland of the cow is particularly susceptible to infections of a wide range of pathogenic bacteria, including both Gram-positive and Gram-negative bacteria. The endotoxins of these pathogenic bacteria include peptidoglycan (PGN), lipoteichoic acid (LTA) and lipopolysaccharide (LPS), and they are the pathogen-associated molecular patterns (PAMPs) to induce mastitis. LPS can directly inhibit proliferation and milk fat synthesis of bovine mammary epithelial cells (BMECs) while inducing mastitis, but it is unclear whether PGN and LTA also have such effects. Furthermore, since the three PAMPs usually appear simultaneously in the udder of cows with mastitis, their synergistic effects on proliferation and milk fat synthesis of BMECs are worth investigating. The immortalized BMECs (MAC-T cells) were stimulated for 24 h using various concentrations of PGN, LTA and LPS, respectively, to determine the doses that could effectively cause inflammatory responses. Next, the cells were stimulated for 24 h with no endotoxins (CON), PGN, LTA, LPS, PGN + LTA, and PGN + LTA + LPS, respectively, with the predetermined doses to analyze their effects on proliferation and milk fat synthesis of BMECs. PGN, LTA and LPS successfully induced inflammatory responses of BMECs with doses of 30, 30 and 0.1 μg/mL, respectively. Although the proliferation of BMECs was significantly inhibited in the following order: LTA < PGN + LTA < PGN + LTA + LPS, there was no change in cell morphology and cell death. LTA significantly promoted the expression of fatty acid synthesis-related genes but did not change the content of intracellular triglyceride (TG), compared with the CON group. The mRNA expression of fatty acid synthesis-related genes in the LPS group was the lowest among all the groups. Meanwhile, LPS significantly decreased the content of intracellular non-esterified fatty acids (NEFAs) and TG, compared with the CON group. PGN had no effects on milk fat synthesis. Co-stimulation with PGN, LTA and LPS significantly increased the expression of fat acid synthesis-related genes and the intracellular NEFAs, but decreased intracellular TG, compared with sole LPS stimulation. Collectively, PGN, LTA and LPS showed an additive effect on inhibiting proliferation of BMECs. The promoting role of LTA in fatty acid synthesis might offset the negative effects of LPS in this regard, but co-stimulation with PGN, LTA and LPS significantly decreased intracellular TG content.