Schisandrin B inhibits inflammation and ferroptosis in S.aureus-induced mastitis through regulating SIRT1/p53/SLC7A11 signaling pathway.

Mastitis, one of the most significant problems in women, is commonly caused by pathogens, especially Staphylococcus aureus (S.aureus). Schisandrin B (SCB), the main abundant derivatives from Schisandra chinensis, has been proven to have the ability to inhibiting inflammation and bacteria. However, few relevant researches systematically illustrate the role SCB in the treatment of mastitis. The aim of the present study is to demonstrate the mechanism that SCB functions in reducing pathological injury to the mammary gland in treating S.aureus-induced mastitis. H&E staining was used to identify pathological changes and injuries in mastitis. The levels of cytokines associated with inflammation were detected by ELISA. Key signals relevant to ferroptosis and Nrf2 signaling pathway were tested by western blot analysis and iron assay kit. Compared with the control group, inflammation-associated factors, such as IL-1ß, TNF-α, MPO activity, increased significantly in S. aureus-treated mice. However, these changes were inhibited by SCB. Ferroptosis-associated factors Fe2+ and MDA increased significantly, and GSH, GPX4 and ferritin expression decreased markedly in S. aureus-treated mice. SCB treatment could attenuate S.aureus-induced ferroptosis. Furthermore, SCB increase SIRT1 and SLC7A11 expression and down-regulated p53 expression and NF-κB activation. In conclusion, SCB alleviates S.aureus-induced mastitis via up-regulating SIRT1/p53/SLC7A11 signaling pathway, attenuating the activation of inflammation-associated cytokines and ferroptosis in the mammary gland tissues.

Forsythiaside A attenuates lipopolysaccharide-induced mouse mastitis by activating autophagy and regulating gut microbiota and metabolism.

Mastitis is an inflammatory disease of the mammary gland with a high incidence in lactating animals, significantly impacting their health and breastfeeding. Moreover, mastitis adversely affects milk quality and yield, resulting in substantial economic losses for the dairy farming industry. Forsythiaside A (FTA), a phenylethanol glycoside analog extracted from Forsythia, exhibits notable anti-inflammatory and antioxidant properties. However, its protective effects and specific mechanisms against mastitis remain unclear. In this study, a lipopolysaccharide (LPS)-induced mouse mastitis model was used to investigate the protective effect of FTA on LPS-induced mastitis and its potential mechanism using histological assays, Western blot, qRT-PCR, FITC-albumin permeability test, 16s rRNA gene sequencing analysis and non-targeted metabolomics assays to investigate the protective effect of FTA on LPS-induced mastitis model and its potential mechanism. The results demonstrated that FTA significantly mitigated LPS-induced mouse mastitis by reducing inflammation and apoptosis levels, modulating the PI3K/AKT/mTOR signaling pathways, inducing autophagy, and enhancing antioxidant capacity and the expression of tight junction proteins. Furthermore, FTA increased the abundance of beneficial microbiota while decreasing the levels of harmful microbiota in mice, thus counteracting the gut microbiota disruption induced by LPS stimulation. Intestinal metabolomics analysis revealed that FTA primarily regulated LPS-induced metabolite alterations through key metabolic pathways, such as tryptophan metabolism. This study confirms the anti-inflammatory and antioxidant effects of FTA on mouse mastitis, which are associated with key metabolic pathways, including the restoration of gut microbiota balance and the regulation of tryptophan metabolism. These findings provide a novel foundation for the treatment and prevention of mammalian mastitis using FTA.

The inhibition effect of caffeic acid on NOX/ROS-dependent macrophages M1-like polarization contributes to relieve the LPS-induced mice mastitis.

The mammary gland is an adipose tissue containing not only adipocytes but also epithelial, endothelial, and immune cells. Epithelial cells and macrophages, as the integral components of the immune system, are on the front line of defense against infection. Our preliminary work proved that caffeic acid (CA) can effectively inhibit the inflammatory cascade of bovine mammary epithelial cells (BMEC) induced by lipopolysaccharide (LPS) and maintain cellular integrity and viability. Here, we investigated the therapeutic effect of CA on LPS-induced mice mastitis and explored its regulatory mechanism on macrophage inflammatory response induced by LPS in vitro. Firstly, the mice mastitis model was established by intramammary injection with 10 µg LPS, after which different CA doses (5, 10, 15 mg/kg) were administered. Then, the pathological section, myeloperoxidase (MPO) activity, proinflammatory factors and chemokines releasement, and redox state of mammary tissues were assessed, confirming CA's effectiveness on mice mastitis. In vitro, we validated the therapeutic relevance of CA in relieving LPS-induced RAW264.7 inflammatory and oxidative stress responses. Moreover, we further provided evidence that CA significantly reduced LPS-induced reactive oxygen species (ROS) generation via NADPH oxidase (NOX), which improved the imbalance relationship between nuclear factor kappa-B (NF-κB) and NF-E2 p45-related factor 2 (Nrf2) and led to a marked weakening of M1 polarization. The NOX-ROS signal inhibited by CA weakened the oxidative burst and neutrophil chemotaxis of macrophages, thus alleviating the immune cascade in mammary gland tissue and reducing the LPS-induced inflammatory damage. Collectively, CA would be a potential candidate or antibacterial synergist for curbing mastitis.

Wogonin attenuates inflammation and oxidative stress in lipopolysaccharide-induced mastitis by inhibiting Akt/NF-κB pathway and activating the Nrf2/HO-1 signaling.

Mastitis is a disease involved in inflammation of breast which affects human and animals. Wogonin is one bioactive compound from many Chinese herbal medicines, which have multiple properties, including anti-inflammatory activity. However, the roles of wogonin in mastitis progression are largely undefined. Mastitis models were established using LPS-treated mice and mammary epithelial cells (MECs). Infiltration of inflammatory cells was analyzed by hematoxylin-eosin staining and myeloperoxidase (MPO) activity. Inflammatory cytokine (TNF-α and IL-1ß) levels were detected via ELISA. The phosphorylation and total of Akt and NF-κB levels and content of Nrf2 and HO-1 were measured via western blot. Cell viability was examined by CCK-8 assay. Oxidative stress was assessed by ROS generation and levels of MDA, GSH, and SOD. Wogonin attenuated LPS-induced infiltration of inflammatory cells, increase of MPO activity and levels of TNF-α and IL-1ß, and activation of the Akt/NF-κB pathway in murine mammary gland tissues, and promoted activation of Nrf2/HO-1 signaling. Wogonin did not affect MEC viability, but mitigated LPS-induced inflammation in MECs by reducing TNF-α and IL-1ß levels. Wogonin relieved LPS-induced oxidative stress in MECs through decreasing ROS generation and MDA level and increasing GSH and SOD levels. Wogonin repressed LPS-induced activation of the Akt/NF-κB pathway in MECs and increased Nrf2/HO-1 signaling activation. Activated Akt/NF-κB signaling or Nrf2/HO-1 signaling inactivation reversed the suppressive effects of wogonin on LPS-induced inflammation and oxidative stress in MECs. Wogonin mitigates LPS-induced inflammation and oxidative stress of MECs via suppressing activation of the Akt/NF-κB signaling and activating Nrf2/HO-1 pathway, indicating the therapeutic potential of wogonin in mastitis.

Protocatechuic acid inhibits LPS-induced mastitis in mice through activating the pregnane X receptor.

Mastitis refers to the inflammation in the mammary gland caused by various reasons. Protocatechuic acid (PCA) exerts anti-inflammatory effect. However, no studies have shown the protective role of PCA on mastitis. We investigated the protective effect of PCA on LPS-induced mastitis in mice and elucidated its possible mechanism. LPS-induced mastitis model was established by injection of LPS into the mammary gland. The pathology of mammary gland, MPO activity and inflammatory cytokine production were detected to evaluate the effects of PCA on mastitis. In vivo, PCA significantly attenuated LPS-induced mammary pathological changes, MPO activity, TNF-α and IL-1ß production. In vitro, the production of inflammatory cytokines TNF-α and IL-1ß was significantly reduced by PCA. Furthermore, LPS-induced NF-κB activation was also inhibited by PCA. In addition, PCA was found to activate pregnane X receptor (PXR) transactivation and PCA dose-dependently increased the expression of PXR downstream molecule CYP3A4. In addition, the inhibitory effect of PCA on inflammatory cytokine production was also reversed when PXR was knocked down. In conclusion, the protective effects of PCA on LPS-induced mastitis in mice through regulating PXR.

Effect of repeated intrauterine infusion of lipopolysaccharides on mastitis in goats.

A single infusion of lipopolysaccharide (LPSs) into the uterus induces inflammation in the mammary gland. This indicates that LPS can translocate from the uterus to the mammary gland. Natural endometritis is characterized by continuous intrauterine inflammation. The aim of the present study was to determine the effect of repeated intrauterine infusion of two different types of LPSs obtained from Escherichia coli O111:B4 (LPS-O111) and O55:B5 (LPS-O55) on the inflammatory status of the mammary glands of goats. Goats were assigned to three groups: LPS-O111, LPS-O55, and saline (control). Saline with (LPS-O111 and 55 groups) and without (control) 100 µg LPS was infused into the uterus continuously for 7 days. Decreased milk yield was detected in both LPS-O111 and LPS-O55 groups 2 days after the first LPS infusion. While somatic cell count (SCC) was significantly increased in all groups 1 day after the first LPS infusion, both LPS infusions further increased SCC 2 days after the first infusion and showed a significantly higher SCC than that in the control group. Plasma LPS-binding protein (LBP) was significantly higher in both LPS groups than in the control group during the days after infusion. In addition, pro-inflammatory cytokines, interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and IL-8, were significantly increased in both LPS infusion groups compared with those in the control group. The LPS-O111 infusion resulted in higher SCC, LBP, TNF-α, and IL-8 concentrations than those in the LPS-O55 group. These results suggest that repeated LPS infusion into the uterus can induce more severe mammary gland inflammation than a single infusion. Interestingly, the mammary tissues recovered from inflammation even though the LPS intrauterine infusion was continued.

The JMJD3 histone demethylase inhibitor GSK-J1 ameliorates lipopolysaccharide-induced inflammation in a mastitis model.

Jumonji domain-containing 3 (JMJD3/KDM6B) is a histone demethylase that plays an important role in regulating development, differentiation, immunity, and tumorigenesis. However, the mechanisms responsible for the epigenetic regulation of inflammation during mastitis remain incompletely understood. Here, we aimed to investigate the role of JMJD3 in the lipopolysaccharide (LPS)-induced mastitis model. GSK-J1, a small molecule inhibitor of JMJD3, was applied to treat LPS-induced mastitis in mice and in mouse mammary epithelial cells in vivo and in vitro. Breast tissues were then collected for histopathology and protein/gene expression examination, and mouse mammary epithelial cells were used to investigate the mechanism of regulation of the inflammatory response. We found that the JMJD3 gene and protein expression were upregulated in injured mammary glands during mastitis. Unexpectedly, we also found JMJD3 inhibition by GSK-J1 significantly alleviated the severity of inflammation in LPS-induced mastitis. These results are in agreement with the finding that GSK-J1 treatment led to the recruitment of histone 3 lysine 27 trimethylation (H3K27me3), an inhibitory chromatin mark, in vitro. Furthermore, mechanistic investigation suggested that GSK-J1 treatment directly interfered with the transcription of inflammatory-related genes by H3K27me3 modification of their promoters. Meanwhile, we also demonstrated that JMJD3 depletion or inhibition by GSK-J1 decreased the expression of toll-like receptor 4 and negated downstream NF-κB proinflammatory signaling and subsequently reduced LPS-stimulated upregulation of Tnfa, Il1b, and Il6. Together, we propose that targeting JMJD3 has therapeutic potential for the treatment of inflammatory diseases.

Houttuynia Essential Oil and its Self-Microemulsion Preparation Protect Against LPS-Induced Murine Mastitis by Restoring the Blood-Milk Barrier and Inhibiting Inflammation.

Mastitis is a common inflammatory disease caused by bacterial infection to the mammary gland that impacts human and animal health and causes economic losses. Houttuynia essential oil (HEO), extracted from Houttuynia cordata Thunb, exhibits excellent antibacterial and anti-inflammatory properties. The aim of the study was to investigate the effects of HEO and a self-microemulsion preparation of HEO (SME-HEO) on inflammation and the blood-milk barrier (BMB) in lipopolysaccharide-induced murine mastitis. HEO and SME-HEO significantly downregulated pro-inflammatory factors TNF-α and IL-1ß, upregulated anti-inflammatory factor IL-10, inhibited MPO expression, and alleviated histopathological injury in murine mammary gland tissues. Additionally, HEO and SME-HEO protected the integrity of the BMB by upregulating the expression of junction proteins ZO-1, claudin-1, claudin-3, and occludin. The anti-inflammatory effect of HEO against murine mastitis was mediated by blocking the MAPK signaling pathway and expression of iNOS. By inhibiting the release of inflammatory factors and protecting the integrity of the BMB, HEO may provide a novel treatment for mastitis.

Nisin Z attenuates lipopolysaccharide-induced mastitis by inhibiting the ERK1/2 and p38 mitogen-activated protein kinase signaling pathways.

Nisin Z is a possible alternative for treating bovine mastitis by inhibiting mastitis-causing pathogens and having anti-inflammatory activity. However, the anti-inflammatory mechanism of nisin Z on mastitis is unknown. Our study aimed to investigate the mechanisms of nisin Z on mastitis. Our results showed that nisin Z inhibited the activation of the ERK1/2 and p38 mitogen-activated protein kinase (MAPK) signaling pathway, decreased the release of pro-inflammatory cytokines (i.e., tumor necrosis factor-α, IL-1ß, and IL-6), and increased the anti-inflammatory cytokine (IL-10) in lipopolysaccharide (LPS)-induced MCF10A cells. After intraperitoneal injection, nisin Z significantly decreased inflammatory cell infiltration in the mammary gland, as well as decreased myeloperoxidase and pro-inflammatory cytokines in serum and mammary gland. Western blot analysis revealed that nisin Z also dramatically suppressed the activation of the ERK1/2 and p38 MAPK signaling pathways in LPS-induced mastitis mice. We also found that nisin Z treatment could enhance the blood-milk barrier. In summary, our study demonstrated that nisin Z exerted an anti-inflammatory effect by inhibiting the ERK1/2 and p38 MAPK signaling pathway and promoting the blood-milk barrier on LPS-induced mastitis.

Selenium and Taurine Combination Is Better Than Alone in Protecting Lipopolysaccharide-Induced Mammary Inflammatory Lesions via Activating PI3K/Akt/mTOR Signaling Pathway by Scavenging Intracellular ROS.

Mastitis is mainly induced by gram-negative bacterial infections, causing devastating economic losses to the global cattle industry. Both selenium (Se) and taurine (Tau) exhibit multiple biological effects, including reducing inflammation. However, no studies have reported the protective effect of the combined use of Se and Tau against mastitis, and the underlying mechanisms remain unclear. In this study, lipopolysaccharide (LPS), the vital virulence factor of gram-negative bacteria, was used to construct the in vivo and vitro mastitis models. The results of in vivo model showed that Se and Tau combination was more effective than either substance alone in reducing tissue hyperemia, edema, and neutrophil infiltration in the mammary acinar cavity, improving the blood-milk barrier in LPS-induced mice mastitis, and decreasing the expression of proinflammatory factors and the activity of MPO. Moreover, Se and Tau combination significantly increased the levels of LPS-induced reduction in PI3K/Akt/mTOR, but the expressions of TLRs and NLRP3 were not significantly changed in the mammary tissue. In the in vitro experiments, the effects of Se and Tau combination or alone on inflammatory factors, inflammatory mediators, MPO activity, and blood-milk barrier were consistent with those in vivo. The Se and Tau combination has also been found to increase the survival rate of BMECs compared with each substance alone via promoting cellular proliferation and inhibiting apoptosis. Also, it has been confirmed that this combination could restore the LPS-induced inhibition in the PI3K/Akt/mTOR signaling pathway. Inhibition of mTOR by Rapamycin counteracted the combined protection of SeMet and Tau against LPS-induced inflammatory damage, the inhibition of PI3K by LY294002 blocked the activation of mTOR, and the accumulation of ROS by the ROS agonist blocked the activation of PI3K. In conclusion, these findings suggested that Se and Tau combination was better than either substance alone in protecting LPS-induced mammary inflammatory lesions by upregulating the PI3K/Akt/mTOR signaling pathway.

The Protective Effects of Lactobacillus plantarum KLDS 1.0344 on LPS-Induced Mastitis In Vitro and In Vivo.

Cow mastitis, which significantly lowers milk quality, is mainly caused by pathogenic bacteria such as E. coli. Previous studies have suggested that lactic acid bacteria can have antagonistic effects on pathogenic bacteria that cause mastitis. In the current study, we evaluated the in vitro and in vivo alleviative effects of L. plantarum KLDS 1.0344 in mastitis treatment. In vitro antibacterial experiments were performed using bovine mammary epithelial cell (bMEC), followed by in vivo studies involving mastitis mouse models. In vitro results indicate that lactic acid was the primary substance inhibiting the E. coli pathogen. Meanwhile, treatment with L. plantarum KLDS 1.0344 can reduce cytokines' mRNA expression levels in the inflammatory response of bMEC induced by LPS. In vivo, the use of this strain reduced the secretion of inflammatory factors IL-6, IL-1ß, and TNF-α, and decreased the activity of myeloperoxidase (MPO), and inhibited the secretion of p-p65 and p-IκBα. These results indicate that L. plantarum KLDS 1.0344 pretreatment can reduce the expression of inflammatory factors by inhibiting the activation of NF-κB signaling pathway, thus exerting prevent the occurrence of inflammation in vivo. Our findings show that L. plantarum KLDS 1.0344 has excellent properties as an alternative to antibiotics and can be developed into lactic acid bacteria preparation to prevent mastitis disease.

GPR109A alleviate mastitis and enhances the blood milk barrier by activating AMPK/Nrf2 and autophagy.

Mastitis causes great psychological and physical pain among women. Our previous studies found that niacin has anti-inflammatory effect, and the realization of this function depends on GPR109A. However, there are no previous reports about the anti-inflammatory function of GPR109A in mastitis. In our study, we observed the effect of niacin on the WT and GPR109A-/- mice mastitis model. The results showed that administration of niacin to WT mice reduced the damage, proinflammatory mediators and protected the integrity of the blood milk barrier in mammary gland. While in GPR109A-/- mice, there was no effect on the above indexes. In mammary epithelial cells, GPR109A was able to promote autophagy and Nrf2 nuclear import through AMPK. In LPS-induced mammary epithelial cells, niacin inhibited the LPS-induced inflammatory response and downregulation of tight junction proteins, and these effects were eliminated by knocking down GPR109A, blocking autophagy or inhibiting Nrf2 nuclear import. These results indicate that in mastitis, GPR109A promotes autophagy and Nrf2 nuclear import through AMPK, thereby inhibiting inflammatory damage to the mammary gland and repairing the blood milk barrier. Our results suggested that GPR109A may be a potential target for the treatment of mastitis.

Corynoline protects lipopolysaccharide-induced mastitis through regulating AKT/GSK3ß/Nrf2 signaling pathway.

Inflammation has been known to be involved in the pathogenesis of mastitis. And anti-inflammatory agent is proposed to be a possible efficient therapeutic strategy for mastitis. Corynoline, a bioactive compound extracted from Corydalis bungeana Turcz., has been reported to have anti-inflammatory effect. However, whether corynoline has protective effect against mastitis remains unclear. The aim of this study was to evaluate the protective effect of corynoline on LPS-induced mastitis in mice. Inflammatory cytokine production was measured by ELISA. The proteins of signaling pathways were detected by western blot analysis. The results showed that treatment of corynoline at the doses of 15, 30, and 60 mg/kg significantly attenuated LPS-induced pathological damage of mammary tissues. Corynoline also ameliorated LPS-induced MPO activity, MDA content, and inflammatory cytokine TNF-α and IL-1ß production in mammary tissues. LPS-induced NF-κB activation was inhibited by corynoline. Furthermore, our results showed corynoline significantly increased the expression of Nrf2 and the phosphorylation levels of AKT and GSK3ß. In conclusion, our results indicated that corynoline protected against LPS-induced mastitis through regulating AKT/GSK3ß/Nrf2 signaling pathway, which subsequently led to the inhibition of NF-κB and inflammatory response.

Forsythiaside a plays an anti-inflammatory role in LPS-induced mastitis in a mouse model by modulating the MAPK and NF-κB signaling pathways.

Forsythiaside A, a major bioactive component extracted from Forsythiae fructus, possesses multiple biological properties, especially anti-inflammatory properties. In the present study, the anti-inflammatory effect of forsythiaside A was investigated in lipopolysaccharide (LPS)-induced acute mastitis in mice. Our results showed that the expression levels of IL-1ß, IL-6, TNF-α, p38 MAPK, IκBα, and NF-κB p65 in the LPS group were all up-regulated, and obvious pathological changes were observed by sectioning. Compared with those in the LPS group, the expression levels of the above factors were significantly reduced, and the inflammation symptoms were also significantly reduced by section observation after forsythiaside A intervention. These results indicated that forsythiaside A effectively inhibited LPS-induced mammary inflammation in mice by attenuating the activation of the NF-κB and p38 MAPK signaling pathways.

Tanshinone I and Tanshinone IIA/B attenuate LPS-induced mastitis via regulating the NF-κB.

BACKGROUND: Mastitis is a common disease occurs in breast-feeding mothers, but published data are poor. This study aimed to study the effects of Tanshinones on treating mastitis. METHODS: Clinical trials performed in 58 breast-feeding mothers were carried out. B-ultrasound and blood test were used to measure the size of breast mass and the change of blood cell counts. BALB/c mice were injected with LPS and then treated by Tanshinone I or Tanshinone IIA/B. Myeloperoxidase (MPO) activity and the release of inflammatory cytokines were tested by MPO kit, RT-qPCR and ELISA. Mouse mammary epithelial cells (mMECs) were isolated and the effects of Tanshinones were measured by conducting CCK-8 assay, flow cytometry, RT-qPCR and ELISA. RESULTS: Patients treated by Cefprozil combined with Tanshinone got better outcomes than patients treated by Cefprozil alone. In animal trials, Tanshinone I and Tanshinone IIA/B significantly reduced MPO activity, and the levels of TNF-α, IL-1ß and IL-6 in serum and mammary gland tissues. In mMECs, Tanshinone I and Tanshinone IIA/B attenuated LPS-induced viability loss and apoptosis. And they effectively inhibited the release of TNF-α, IL-1ß and IL-6. Also, Tanshinone I and Tanshinone IIA/B significantly attenuated LPS-evoked NF-κB activation. CONCLUSION: Tanshinone I and Tanshinone IIA/B have potentials in treating mastitis. The beneficial effects might be through regulating NF-κB activation.

Lysine-specific demethylase 1 (LSD1) serves as an potential epigenetic determinant to regulate inflammatory responses in mastitis.

It is well-established that lysine-specific demethylase 1 (LSD1) is the first identified histone demethylase. Based on its demethylase enzymatic activity, LSD1 plays a pivotal role in vast range of cellular processes and cancers, but the understanding of its effects on inflammation is relatively limited. Using in vivo models of lipopolysaccharide (LPS)-induced inflammation and in vitro assays in mouse mammary epithelial cells, we identified the novel regulatory roles and underlying mechanisms of LSD1 on LPS-induced mastitis. Mammary gland and cells were collected for the following experiments after treatment. Histological changes were determined by H&E. Western blot analysis was used to detect the protein expression. ELISA and real-time PCR were used to evaluate protein and mRNA expression of inflammatory genes. Our results showed that LPS treatment resulted in a significant increase in LSD1 protein expression. GSK-LSD1 is a selective inhibitor of LSD1 enzyme activity. Treatment of mice with GSK-LSD1 inhibited LSD1 activity, reduced inflammatory cells recruitment to tissues and attenuated LPS-induced damage in mammary gland. Mechanistic investigations suggested that LSD1 inhibition led to the increase of histone H3K4me2 and H3K9me2. Furthermore, GSK-LSD1 inhibition of LSD1 further inhibited nuclear factor κ-B (NF-κB) signaling cascades, and subsequently inhibited the production of cytokines (TNF-α, IL-6 and IL-1ß) in mammary gland. Taken together, our data reveal LSD1 as a potential regulator of inflammation and improve our understanding of epigenetic control on inflammation.

Gambogic acid alleviates inflammation and apoptosis and protects the blood-milk barrier in mastitis induced by LPS.

Mastitis is one of the most common diseases among dairy cows. There is still much debate worldwide as to whether antibiotic therapy should be given to dairy cows, or if natural products should be taken as a substitute for antibacterial therapy. As the antibiotic treatment leads to the bacterial resistance and drug residue in milk, introducing natural products for mastitis is becoming a trend. This study investigates the mechanisms of the protective effects of the natural product gambogic acid (GA) in lipopolysaccharide (LPS)-induced mastitis. For in vitro treatments, it was found that GA reduced IL-6, TNF-α, and IL-1ß levels by inhibiting the phosphorylation of proteins in the nuclear factor κB (NF-κB) and the mitogen-activated protein kinase (MAPK) pathway. GA also maintained a stable membrane mitochondrial potential and inhibited the overproduction of reactive oxygen species, which protected the cells from apoptosis. On the other hand, in vivo treatments with GA were found to reduce pathological symptoms markedly, and protected the blood-milk barrier from damage induced by LPS. The results demonstrate that GA plays a vital role in suppressing inflammation, alleviating the apoptosis effect, and protecting the blood-milk barrier in mastitis induced by LPS. Thus, these results suggest that the natural product GA plays a potential role in mastitis treatment.

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

Mastitis is acute inflammation caused by microbial infections in the mammary glands. This disease is extremely harmful to lactating mothers. The preferred clinical strategy is antibiotic treatment, but this method results in resistance and side effects. Lixisenatide, a kind of glucagon-like peptide-1 (GLP-1) receptor agonist, is typically used for the treatment of type II diabetes. It is unknown whether lixisenatide possesses a beneficial role in mastitis. In the current study, we assessed the protective effects of lixisenatide against lipopolysaccharide (LPS) stimulation in MAC-T bovine mammary epithelial cells (MECs). Our findings show that lixisenatide attenuated LPS-induced oxidative stress by reducing reactive oxygen species (ROS) production and nicotinamide adenine dinucleotide phosphate (NADPH) oxidases-1 (NOX-1) expression in MAC-T MECs. Additionally, lixisenatide inhibited LPS-induced expression and secretion of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and interleukin 1ß (IL-1ß). We also found that lixisenatide suppressed LPS-induced expression of matrix metalloproteinase 2 (MMP-2) and metalloproteinase 9 (MMP-9), and reduced the expression of toll-like receptor 4 (TLR4) (a typical receptor of LPS), its downstream molecule myeloid differentiation factor 88 (MyD88), and the phosphorylation of TGF ß-activated kinase 1 (TAK1). Notably, lixisenatide decreased the nuclear levels of nuclear factor-κB (NF-κB) and its transcriptional activity. These findings suggest that lixisenatide might become a possible therapeutic agent for the treatment of mastitis by weakening oxidative stress and the inflammatory response in MECs.

Morin alleviates LPS-induced mastitis by inhibiting the PI3K/AKT, MAPK, NF-κB and NLRP3 signaling pathway and protecting the integrity of blood-milk barrier.

Mastitis is a common veterinary clinical disease that restricts the development of dairy farming around the world. Morin, extracted from Mulberry Tree and other herbs, has been reported to possess the function of anti-bacteria, anti-oxidant, and anti-inflammatory. However, whether morin could protect lipopolysaccharide (LPS)-induced mouse mastitis in vivo has not well known. This study firstly aims to evaluate the effects of morin on LPS-induced mouse mastitis in vivo, and then try to illustrate the mechanism involved in the process. Before injected with LPS, mice were intraperitoneally pre-injected with different concentrations of morin, and mice of the control and LPS group were injected with the same amount of saline. Pathologic changes of mammary gland were determined by histopathological examination. Myeloperoxidase (MPO) activities of mammary gland were determined by the MPO kits. The mRNA expressions of inflammatory cytokines including TNF-α, IL-1ß and IL-6, and those of chemokine factors CCL2 and CXCL2, and those of tight junctions occludin claudin-3 were examined by qRT-PCR analysis. The activities of IκB, p65, ERK, P38, AKT, PI3K, NLPR3, claudin-1, claudin-3 and occludin were determined by western blotting. The results showed that morin alleviated LPS-induced edema, destructed structures and infiltrated inflammatory cells of mammary gland. Morin administration significantly decreased LPS-induced TNF-α, IL-1ß, IL-6, CCL2 and CXCL2 mRNA expressions. Furthermore, western blot analysis also showed that morin significantly reduced LPS-induced phosphorylation of p65, IκB, p38 and ERK, and enhanced LPS-induced phosphorylation of AKT and PI3K. It was also found that LPS-decreased claudin-3 and occludin expressions were also inhibited by morin treatment. In summary, above results suggest that morin indeed protect LPS-induced mouse mastitis in vivo, and the mechanism was through inhibiting the PI3K/AKT, MAPK, NF-κB and NLRP3 signaling pathways and protecting the integrity of blood-milk barrier by regulating the tight junction proteins expressions.

Schisandrin A protects against lipopolysaccharide-induced mastitis through activating Nrf2 signaling pathway and inducing autophagy.

Schisandrin A (Sch A), a dibenzocyclooctadiene lignan extracted from Schisandra chinensis (Turcz.) Baill., has anti-oxidant and anti-inflammatory effects, but the effect on masitits has not been studied. Therefore, we investigated the effect of Sch A in cell and mouse models of lipopolysaccharide (LPS)-induced mastitis. Studies in vivo showed that Sch A reduced LPS-induced mammary injury and the production of pro-inflammatory mediators. Sch A also decreased the levels of pro-inflammatory mediators and activated nuclear factor-E2 associated factor 2 (Nrf2) signaling pathway in mouse mammary epithelial cells (mMECs). The Nrf2 inhibitor partially abrogated the downregulation of Sch A on LPS-induced inflammatory response. In addition, LPS stimulation suppressed autophagy, while both Sch A and the autophagy inducer rapamycin activated autophagy in mMECs, which down-regulated inflammatory response. Sch A also restrained LPS-induced phosphorylation of mammalian target of rapamycin (mTOR) and activated AMP-activated protein kinase (AMPK) and unc-51 like kinase 1 (ULK1). In summary, these results suggest that Sch A exerts protective effects in LPS-induced mastitis models by activating Nrf2 signaling pathway and inducing autophagy and the autophagy is initiated by suppressing mTOR signaling pathway and activating AMPK-ULK1 signaling pathway.