A fiber-enriched diet alleviates Staphylococcus aureus-induced mastitis by activating the HDAC3-mediated antimicrobial program in macrophages via butyrate production in mice.

Mounting evidence suggests that the gut microbiota plays an important role in the pathogenesis of mastitis, an important disease affecting the health of lactating women and the development of the dairy industry. However, the effect of the regulation of the gut microbiota by dietary components on mastitis development remains unknown. In this study, we found that a fiber-enriched diet alleviated Staphylococcus aureus (S. au)-induced mastitis in mice, which was dependent on the gut microbiota as depletion of the gut microbiota by antibiotics abolished this protective effect. Likewise, fecal microbiota transplantation (FMT) from high-inulin (HI)-treated mice (HIF) to recipient mice improved S. au-induced mastitis in mice. Consumption of an HI diet and HIF increased fecal short-chain fatty acid (SCFA) levels compared with the control group. Moreover, treatment with SCFAs, especially butyrate, alleviated S. au-induced mastitis in mice. Mechanistically, consumption of an HI diet enhanced the host antimicrobial program in macrophages through inhibiting histone deacetylase 3 by the production of butyrate. Collectively, our results suggest that modulation of the gut microbiota and its metabolism by dietary components is a potential strategy for mastitis intervention and serve as a basis for other infectious diseases.

Hexadecanamide alleviates Staphylococcus aureus-induced mastitis in mice by inhibiting inflammatory responses and restoring blood-milk barrier integrity.

Subacute ruminal acidosis (SARA) has been demonstrated to promote the development of mastitis, one of the most serious diseases in dairy farming worldwide, but the underlying mechanism is unclear. Using untargeted metabolomics, we found hexadecanamide (HEX) was significantly reduced in rumen fluid and milk from cows with SARA-associated mastitis. Herein, we aimed to assess the protective role of HEX in Staphylococcus aureus (S. aureus)- and SARA-induced mastitis and the underlying mechanism. We showed that HEX ameliorated S. aureus-induced mastitis in mice, which was related to the suppression of mammary inflammatory responses and repair of the blood-milk barrier. In vitro, HEX depressed S. aureus-induced activation of the NF-κB pathway and improved barrier integrity in mouse mammary epithelial cells (MMECs). In detail, HEX activated PPARα, which upregulated SIRT1 and subsequently inhibited NF-κB activation and inflammatory responses. In addition, ruminal microbiota transplantation from SARA cows (S-RMT) caused mastitis and aggravated S. aureus-induced mastitis, while these changes were reversed by HEX. Our findings indicate that HEX effectively attenuates S. aureus- and SARA-induced mastitis by limiting inflammation and repairing barrier integrity, ultimately highlighting the important role of host or microbiota metabolism in the pathogenesis of mastitis and providing a potential strategy for mastitis prevention.

Lactobacillus reuteri inhibits Staphylococcus aureus-induced mastitis by regulating oxytocin releasing and gut microbiota in mice.

Mastitis is the most frequent disease of cows and has well-recognized detrimental effects on animal wellbeing and dairy farm profitability. With the advent of the postantibiotic era, alternative antibiotic agents, especially probiotics, have received increasing attention in the treatment of mastitis. Based on research showing that Lactobacillus reuteri (L. reuteri) has anti-inflammatory effects, this study explored the protective effects and mechanisms of L. reuteri against mastitis induced by Staphylococcus aureus (S. aureus) in mice. First, mice with S. aureus-induced mastitis were orally administered L. reuteri, and the inflammatory response in the mammary gland was observed. The results showed that L. reuteri significantly inhibited S. aureus-induced mastitis. Moreover, the concentration of oxytocin (OT) and protein expression of oxytocin receptor (OTR) were measured, and inhibition of OTR or vagotomy reversed the protective effect of L. reuteri or its culture supernatant (LCS) on S. aureus-induced mastitis. In addition, in mouse mammary epithelial cells (MMECs), OT inhibited the inflammation induced by S. aureus by inhibiting the protein expression of OTR. It was suggested that L. reuteri protected against S. aureus-induced mastitis by releasing OT. Furthermore, microbiological analysis showed that the composition of the microbiota was altered, and the relative abundance of Lactobacillus was significantly increased in gut and mammary gland after treatment with L. reuteri or LCS. In conclusion, our study found the L. reuteri inhibited the mastitis-induced by S. aureus via promoting the release of OT, and treatment with L. reuteri increased the abundance of Lactobacillus in both gut and mammary gland.

The rumen microbiota contributed to the development of mastitis induced by subclinical ketosis.

BACKGROUND: Mastitis is a serious disease which affects animal husbandry, particularly in cow breeding. The etiology of mastitis is complex and its pathological mechanism is not yet fully understood. Our previous research in clinical investigation has revealed that subclinical ketosis can increase the number of somatic cell counts (SCC) in milk, although the underlying mechanism remains unclear. Recent studies have further confirmed the significant role of mastitis. RESULTS: In this study, we aimed to examine the SCC, rumen microbiota, and metabolites in the milkmen of cows with subclinical ketosis. Additionally, we conducted a rumen microbiota transplant into mice to investigate the potential association between rumen microbiota disturbance and mastitis induced by subclinical ketosis in dairy cows. The study has found that cows with subclinical ketosis have a higher SCC in their milk compared to healthy cows. Additionally, there were significant differences in the rumen microbiota and the level of volatile fatty acid (VFA) between cows with subclinical ketosis and healthy cows. Moreover, transplanting the rumen microbiota from subclinical ketosis and mastitis cows into mice can induce mammary inflammation and liver function damage than transplanting the rumen flora from healthy dairy cows. CONCLUSIONS: In addition to the infection of mammary gland by pathogenic microorganisms, there is also an endogenous therapeutic pathway mediated by rumen microbiota. Targeted rumen microbiota modulation may be an effective way to prevent and control mastitis in dairy cows.

Aryl hydrocarbon receptor activation by Lactobacillus reuteri tryptophan metabolism alleviates Escherichia coli-induced mastitis in mice.

The intestinal microbiota has been associated with the occurrence and development of mastitis, which is one of the most serious diseases of lactating women and female animals, but the underlying mechanism has not yet been elucidated. Aryl hydrocarbon receptor (AhR) activation by microbiota tryptophan metabolism-derived ligands is involved in maintaining host homeostasis and resisting diseases. We investigated whether AhR activation by microbiota-metabolic ligands could influence mastitis development in mice. In this study, we found that AhR activation using Ficz ameliorated mastitis symptoms, which were related to limiting NF-κB activation and enhancing barrier function. Impaired AhR activation by disturbing the intestinal microbiota initiated mastitis, and processed Escherichia coli (E. coli)-induced mastitis in mice. Supplementation with dietary tryptophan attenuated the mastitis, but attenuation was inhibited by the intestinal microbiota abrogation, while administering tryptophan metabolites including IAld and indole but not IPA, rescued the tryptophan effects in dysbiotic mice. Supplementation with a Lactobacillus reuteri (L. reuteri) strain with the capacity to produce AhR ligands also improved E. coli-induced mastitis in an AhR-dependent manner. These findings provide evidence for novel therapeutic strategies for treating mastitis, and support the role of metabolites derived from the intestinal microbiota in improving distal disease.

Carbon Dots as Potential Therapeutic Agents for Treating Non-Alcoholic Fatty Liver Disease and Associated Inflammatory Bone Loss.

Nonalcoholic fatty liver disease (NAFLD) has emerged as one of the most significant metabolic diseases worldwide and is associated with heightened systemic inflammation, which has been shown to foster the development of extrahepatic complications. So far, there is no definitive, effective, and safe treatment for NAFLD. Although antidiabetic agents show potential for treating NAFLD, their efficacy is significantly limited by inadequate liver accumulation at safe doses and unwanted side effects. Herein, we demonstrate that pharmacologically active carbon dots (MCDs) derived from metformin can selectively accumulate in the liver and ameliorate NAFLD by activating hepatic PPARα expression while maintaining an excellent biosafety. Interestingly, MCDs can also improve the function of extrahepatic organs and tissues, such as alleviating alveolar inflammatory bone loss, in the process of treating NAFLD. This study proposes a feasible and safe strategy for designing pharmacologically active MCDs to target the liver, which regulates lipid metabolism and systemic inflammation, thereby treating NAFLD and its related extrahepatic complications.

Retinoic acid ameliorates low-grade endotoxemia-induced mastitis by limiting inflammatory responses in mice.

Mastitis is a serious disease for humans and animals, which causes huge economic losses in the dairy industry and is hard to prevent due to the complex and unclear pathogenesis. Subacute ruminal acidosis (SARA) has contributed to the development of mastitis by inducing ruminal dysbiosis and subsequent low-grade endotoxemia (LGE), however, how ruminal metabolic changes regulate this progress is still unclear. Our previous study revealed that cows with SARA had increased ruminal retinoic acid (RA) levels, a metabolic intermediate of vitamin A that plays an essential role in mucosal immune responses. Hence, the aim of this study was to investigate the protective effect of RA on LGE-induced mastitis and the underlying mechanisms in mice. The results showed that RA alleviated LGE-induced mastitis, as evidenced by RA significantly reduced the increase in mammary proinflammatory cytokines and improved blood-milk barrier injury caused by LGE. In addition, RA increased the expression of tight junction proteins, including ZO-1, occludin and claudin-3. Furthermore, we found that RA limited the mammary inflammatory responses by inhibiting the activation of NF-κB and NLRP3 signaling pathways. These findings suggest that RA effectively alleviates LGE-induced mastitis and implies a potential strategy for the treatment and prevention of mastitis and other diseases.

Phytosphingosine alleviates Staphylococcus aureus-induced mastitis by inhibiting inflammatory responses and improving the blood-milk barrier in mice.

Mastitis is one of the common diseases in dairy cows which threatens the health of cows and impacts on economic benefits seriously. Recent studies have been showed that Subacute Ruminal Acidosis (SARA) increased the susceptibility of cow mastitis. SARA leads the disturbance of the rumen microbiota, and the rumen bacterial disordered community is an important endogenous factor of cow mastitis. That is to say, cows which suffer from SARA have a disordered rumen microbiota, a prolonged decline in ruminal PH and a high level of lipopolysaccharide (LPS) in the rumen, blood. Therefore, ruminal metabolism is closely related to the rumen microbiota. However, the specific mechanism of SARA and mastitis still not clear. We found an intestinal metabolite according to the metabonomics, which is correlated to inflammation. Phytophingosine (PS), a product from rumen fluid and milk of the cows which suffer from SARA and mastitis. It has the effect of killing bacteria and anti-inflammatory. Emerging evidences indicate that PS can alleviate inflammatory diseases. However, how PS affects mastitis is largely unknown. In this study, we explored the concrete role of PS on Staphylococcus aureus (S. aureus) -induced mastitis in mice. We found that PS obviously decreased the level of the proinflammatory cytokines. Meanwhile, PS also significantly relieved the mammary gland inflammation caused by S. aureus and restored the function of the blood-milk barrier. Here, we showed that PS increased the expression of the classic Tight-junctions (TJs) proteins including ZO-1, Occludin and Claudin-3. Moreover, PS improves S. aureus-induced mastitis by inhibiting the activation of the NF-κB and NLRP3 signaling pathways. These data indicated that PS relieved S. aureus-induced mastitis effectively. This also provides a reference for exploring the correlation between the intestinal metabolism and inflammation.

ZEA mediates autophagy through the ROS-AMPK-m-TOR pathway to enhance the susceptibility of mastitis induced by Staphylococcus aureus in mice.

Mastitis is an inflammatory response of the mammary tissue caused by pathogenic bacterial infections, especially Staphylococcus aureus (S. aureus). Zearalenone (ZEA) is one of the common mycotoxins in moldy feed, which usually affects the cow's resistance to pathogenic microorganisms. However, it is not well understood whether ZEA affects the development of mastitis. Therefore, this study aimed to investigate the role of ZEA in the development of S. aureus-induced mastitis in mice. The results showed that administered daily by gavage for one week of ZEA (40 mg/kg) aggravated the severity of mastitis induced by S. aureus. Furthermore, we found that ZEA promotes the adhesion and invasion of S. aureus into mouse mammary epithelial cells (MMEC) by activating autophagy, and the activation of autophagy mediated by ROS-AMPK-m-TOR pathway. Taken together, the results showed that ZEA enhances S. aureus-induced mastitis susceptibility through activating autophagy mediated by ROS-AMPK-mTOR signaling pathway.

Bacillus subtilis ameliorates Escherichia coli-induced endometritis in mice via maintaining endometrial barrier and inhibiting inflammatory response.

Endometritis is a common obstetric disease that occurs most frequently after parturition in a variety of animals. Animal infertility due to endometritis severely hinders animal husbandry and often causes serious economic losses to the dairy farming industry. According to reports, Bacillus subtilis (B. subtilis) can prevent pathogenic colonization of epithelial cells and exert immunostimulatory effects. The present study aimed to reveal the protective effect of B. subtilis on endometritis induced by Escherichia coli (E. coli) in mice. The experimental model required in this experiment was established by injecting E. coli intrauterinely, and different concentrations of B. subtilis H28 were administered 10 days before E. coli injection. The pathological changes in the uterine tissue of mice were assessed by haematoxylin-eosin (H&E) staining. Myeloperoxidase (MPO) activity measurements and enzyme-linked immunosorbent assay (ELISA) based measurement of pro-inflammatory cytokines levels were performed. Activation of NF-κB signaling pathway were detected by Western blot, and the changes in the levels of tight junction proteins (TJPs) was analyzed using Western blot detection and quantitative real-time polymerase chain reaction (qRT-PCR). As seen from the results, B. subtilis H28 pretreatment decreased uterine neutrophil infiltration, IL-1ß and TNF-α production, and the NF-κB activation during endometritis induced by E. coli. In addition, B. subtilis H28 significantly increased the expression of the tight junction proteins ZO-1, claudin-3 and occludin in uterine infected with E. coli. In conclusion, in the present study, we found that B. subtilis H28 ameliorated E. coli-induced endometritis by maintaining the endometrial barrier and inhibiting the inflammatory response.

Probiotic Enterococcus mundtii H81 inhibits the NF-κB signaling pathway to ameliorate Staphylococcus aureus-induced mastitis in mice.

Mastitis is part of the aggressive diseases that affecting the development of dairy farming. Lactic acid bacteria (LAB), an important microbiological agent of gastrointestinal flora, can effectively promote the development of the immune system. Herein, the objectives of this study is to explore the protective role of LAB on Staphylococcus aureus(S. aureus)-induced mastitis in mice. 88 strains of suspected LAB were isolated from the milk of healthy dairy cows. Antibacterial activity was screened, and the 16S rRNA sequence analysis showed that the bacteria were Enterococcus mundtii H81 (E. mundtii H81). Furthermore, the model of mastitis has been established by nipple duct injection of S. aureus in mice, while E. mundtii H81 was treated 2 h before S. aureus injection. Twenty-four hours later of S. aureus infection, the mammary gland tissues were collected. The pathological changes of the mammary gland were observed by H&E staining. The levels of TNF-α and IL-1ß were measured by ELISA and the myeloperoxidase (MPO) activity was measured by the MPO assay kit. We also observed the changes of nuclear transcription factor kappa B (NF-κB) by using western blotting. The results showed that E. mundtii H81 pretreatment reduced neutrophil infiltration, and significantly reduce the secretion of TNF-α and IL-1ß, down-regulate the phosphorylation of p65 NF-κB and IκB, and the expression of tight junction protein Claudin 3 and ZO-1 was up-regulated. Collectively, our findings showed that E. mundtii H81 protects mammary gland from S. aureus-induced mastitis, which may be a candidate of treatment for mastitis infected by S. aureus.

TLR2, TLR4, and NLRP3 mediated the balance between host immune-driven resistance and tolerance in Staphylococcus aureus-infected mice.

Staphylococcus aureus (S. aureus) is a gram-positive pathogen that can cause infectious diseases in mammals. S. aureus-induced host innate immune responses have a relationship with Toll-like receptor 2 (TLR2), TLR4, and Nod-like receptor pyrin domain-containing protein 3 (NLRP3). However, the detailed roles of TLR2, TLR4, and NLRP3 in regulating the host inflammatory response to S. aureus infection remain unclear. Our data indicated that the S. aureus-induced mortality was aggravated by deficiency of TLR2, TLR4, and NLRP3 in mice. In the subsequent experiment, we found that during S. aureus infection, the roles of TLR2, TLR4, and NLRP3 seemed to be different at multiple timepoints. The deficiency of TLR2, TLR4, or NLRP3 attenuated the expression of High-mobility group box protein 1 (HMGB1) and Hyaluronic acid-binding protein 2 (HABP2), which is accompanied by decreased proinflammatory cytokine (TNF-α), chemokine (RANTES), and anti-inflammatory cytokine (IL-10) production in lungs and serum at 3 h and 6 h post-infection. However, with S. aureus infection prolonged (24 h post-infection), the trend was diametrically opposite. The results showed that deficiency of TLR2, TLR4, or NLRP3 aggravated HABP2 and HMGB1 expression, which is accompanied by enhanced proinflammatory cytokine (TNF-α), chemokine (RANTES), and anti-inflammatory cytokine (IL-10) production in lungs and serum. These results were consistent with the data observed in S. aureus-infected bone marrow-derived macrophages (BMDMs). All these results suggested that during S. aureus infection, TLR2, TLR4, and NLRP3 has time-dependent effect in regulating the balance between immune-driven resistance and tolerance.

Kynurenic acid ameliorates lipopolysaccharide-induced endometritis by regulating the GRP35/NF-κB signaling pathway.

Endometritis is a serious reproductive disease in mammals that commonly results in reproductive loss and even permanent infertility. Kynurenic acid (KYNA) is the main bioactive metabolite of tryptophan degradation and exhibits neuroprotective and anticonvulsant properties. However, little is known about the role of KYNA in achieving endometritis remission. This study investigated the protective effects and mechanisms of KYNA using a mouse model of against lipopolysaccharide (LPS)-induced endometritis. The endometritis model was induced by an intrauterine injection of LPS, and KYNA was intraperitoneally injected before and two hours after LPS treatment. Twenty-four hours after LPS administration, pathological changes in uterine tissues were observed by hematoxylin- and eosin (H&E) staining. The levels of the inflammatory factors, TNF-α and IL-1ß, were measured by ELISA. The myeloperoxidase (MPO) activity in uterine tissues was detected using MPO kits and immunohistochemistry. Furthermore, the expression of signaling pathway proteins and tight junction proteins occludin and ZO-1 in uterine tissues was detected by western blot. KYNA prominently inhibited uterine pathological injury and neutrophil infiltration and restricted the secretion of TNF-α and IL-1ß in the uteri of subjects with endometritis. Furthermore, KYNA upregulated the levels of the tight junction proteins (TJPs)occludin and ZO-1 in the uterus. In vitro, KYNA inhibited LPS-induced TNF-α and IL-1ß production, and NF-κB activation in mouse endometrial epithelial cells (mEECs). In addition, KYNA increased the expression of G protein-coupled receptor 35 (GPR35) and inhibition of GPR35 reversed the anti-inflammatory effects of KYNA. In conclusion, KYNA protected against LPS-induced endometritis by maintaining epithelial barrier permeability and suppressing proinflammatory responses via the GRP35/NF-κB signaling pathway.

Cadmium induces liver dysfunction and ferroptosis through the endoplasmic stress-ferritinophagy axis.

Cadmium (Cd) is a type of high-risk heavy metal that can damage organs such as the liver, but its mechanism is not yet clear. Ferroptosis is a newly discovered mode of regulatory cell death. We explored whether ferroptosis is involved in Cd-induced liver damage and the underlying mechanism. Our research showed that Cd induced liver damage by inducing ferroptosis, and the use of ferroptosis inhibitors reduced the degree of liver damage. Moreover, the occurrence of ferroptosis was accompanied by the activation of the PERK-eIF2α-ATF4-CHOP signaling pathway, and inhibiting endoplasmic reticulum (ER) stress reduced ferroptosis demonstrating that ferroptosis induced by Cd is dependent on ER stress. In addition, chloroquine, a common autophagy inhibitor, mitigated ferroptosis caused by Cd exposure. Then, the iron chelator deferoxamine reduced Cd-induced lipid peroxidation and cell death, demonstrating that the iron regulation disorder caused by ferritin phagocytosis contributes to the Cd-induced ferroptosis. In conclusion, our results show that Cd-induced liver toxicity is accompanied by ferroptosis, which contributes to Cd inducing oxidative stress to trigger autophagy and ER stress to promote the process of ferroptosis.

DNaseI protects lipopolysaccharide-induced endometritis in mice by inhibiting neutrophil extracellular traps formation.

Endometritis is an inflammatory of the inner lining of the uterus caused by bacterial infections that affect female reproductive health in humans and animals. Neutrophil extracellular traps (NETs) have the ability to resist infections that caused by pathogenic invasions. It has been proved that the formation of NETs is related to certain inflammatory diseases, such as mastitis and chronic obstructive pulmonary disease (COPD). However, there are sparse studies related to NETs and endometritis. In this study, we investigated the role of NETs in lipopolysaccharide (LPS)-induced acute endometritis in mice and evaluated the therapeutic efficiency of DNaseI. We established LPS-induced endometritis model in mice and found that the formation of NETs can be detected in the mice uterine tissues in vivo. In addition, DNaseI treatment can inhibit NETs construction in LPS-induced endometritis in mice. Moreover, myeloperoxidase (MPO) activity assay indicated that DNaseI treatment remarkably alleviated the inflammatory cell infiltrations. ELISA test indicated that the treatment of DNaseI significantly inhibited the expression of the proinflammatory cytokines TNF-α, and IL-1ß. Also, DNaseI was found to increase proteins expression of the uterine tissue tight junctions and suppress LPS-induced NF-κB activation. All the results indicated that DNaseI effectively inhibits the formation of NETs by blocking the NF-κB signaling pathway and enhances the expression of tight junction proteins, consequently, alleviates inflammatory reactions in LPS-induced endometritis in mice.

Changes of microbial and metabolome of the equine hindgut during oligofructose-induced laminitis.

BACKGROUND: Laminitis is a common and serve disease which caused by inflammation and pathological changes of the laminar junction. However, the pathologic mechanism remains unclear. In this study we aimed to investigate changes of the gut microbiota and metabolomics in oligofructose-induced laminitis of horses. RESULTS: Animals submitted to treatment with oligofructose had lower fecal pH but higher lactic acid, histamine, and Lipopolysaccharide (LPS) in serum. Meanwhile, oligofructose altered composition of the hindgut bacterial community, demonstrated by increasing relative abundance of Lactobacillus and Megasphaera. In addition, the metabolome analysis revealed that treatment with oligofructose decreased 84 metabolites while 53 metabolites increased, such as dihydrothymine, N3,N4-Dimethyl-L-arginine, 10E,12Z-Octadecadienoic acid, and asparagine. Pathway analysis revealed that aldosterone synthesis and secretion, regulation of lipolysis in adipocytes, steroid hormone biosynthesis, pyrimidine metabolism, biosynthesis of unsaturated fatty acids, and galactose metabolism were significantly different between healthy and laminitis horses. Furthermore, correlation analysis between gut microbiota and metabolites indicated that Lactobacillus and/or Megasphaera were positively associated with the dihydrothymine, N3,N4-Dimethyl-L-arginine, 10E,12Z-Octadecadienoic acid, and asparagine. CONCLUSIONS: These results revealed that disturbance of gut microbiota and changes of metabolites were occurred during the development of equine laminitis, and these results may provide novel insights to detect biomarkers for a better understanding of the potential mechanism and prevention strategies for laminitis in horses.

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.

Role of Liver X Receptor in Mastitis Therapy and Regulation of Milk Fat Synthesis.

Mastitis is important disease that causes huge economic losses in the dairy industry. In recent years, antibiotic therapy has become the primary treatment for mastitis, however, due to drug residue in milk and food safety factors, we lack safe and effective drugs for treating mastitis. Therefore, new targets and drugs are urgently needed to control mastitis. LXRα, one of the main members of the nuclear receptor superfamily, is reported to play important roles in metabolism, infection and immunity. Activation of LXRα could inhibit LPS-induced mastitis. Furthermore, LXRα is reported to enhance milk fat production, thus, LXRα may serve as a new target for mastitis therapy and regulation of milk fat synthesis. This review summarizes the effects of LXRα in regulating milk fat synthesis and treatment of mastitis and highlights the potential agonists involved in both issues.

Sodium butyrate alleviates lipopolysaccharide-induced endometritis in mice through inhibiting inflammatory response.

Endometritis is commonly occurred in dairy cows after calving and results in a great deal of property damage. Although numerous studies have been performed to find the therapeutic agents for endometritis, the incidence of this disease remains high. Short-chain fatty acids (SCFAs), the major metabolic products of anaerobic bacteria fermentation in the gut, have been reported to exhibit anti-inflammatory properties. Therefore, the purpose of this study was to investigate the protective effects and mechanisms of sodium butyrate (SB) on lipopolysaccharide (LPS)-induced endometritis in mice. The mice were administered by intraperitoneal injection of SB at 1 h before LPS injection. 24 h later, the uterus tissues were collected. Hematoxylin and eosin (H & E) stained sections of uterus were used to determine the degree of the damage. Uterine myeloperoxidase (MPO) activity was used to analyze neutrophil granulocytes concentration. The levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) were measured by ELISA. The activation of the NF-κB signaling pathway proteins were detected by Western blot analysis. The results showed that SB significantly attenuated the pathological injury of the uterus tissues. SB also suppressed LPS-induced MPO activity and the production of inflammatory cytokines TNF-α and IL-1ß. Furthermore, Western blot analysis showed that SB inhibited the activation of NF-κB signaling pathway. In addition, SB could inhibit histone deacetylases. In summary, SB protects against LPS-induced endometritis through HDAC inhibition.

Dimethyl itaconate protects against lippolysacchride-induced mastitis in mice by activating MAPKs and Nrf2 and inhibiting NF-κB signaling pathways.

Mastitis, as the main disease to affect the dry dairy cow with the characterized by increasing number of somatic cells in milk and reducing milk production, has been known as one of the most serious expensive disease for the dairy industry. Escherichia coli (E.coli), a gram negative bacterial, have normally been considered to be an opportunistic pathogen that can invade the mammary gland sometimes to cause inflammatory diseases. Lippolysacchride (LPS), as the co-cell wall component of the Escherichia coli (E.coli), is the main virulence factors to induce acute inflammation. Itaconate is an endogenous metabolite which has recently been reported to regulate the macrophage function and has the ability to reduce the secretion of pro-inflammatory cytokines, such as IL-6 and IL-12. Here, the aim of this study is to investigate the protective role of dimethyl itaconate (DI)-the membranepermeable derivative of itaconate, on LPS-induced mastitis in mice. To establish the model of mastitis, mice 5-7 day after delivery were utilized by nipple duct injection of LPS, while DI was treated 24h intraperitoneally before LPS injection. Further, the hematoxylin-eosin (H&E) staining was used to evaluate the pathological changes of the mammary gland, the inflammatory cytokines of TNF-α and IL-1ß and the myeloperoxidase (MPO) activity were also measured respectively by enzyme-linked immunosorbent assay (ELISA) and MPO assay kit. To clarify the underling mechanisms of the protective role of DI on mastitis, the MAPKs, NF-κB and Nrf2 signaling pathways were detected via western blotting. The results demonstrated that DI markedly decreased the pathological injury of mammary, and considerably reduced the production of TNF-α and IL-1ß, as well as up-regulated the Nrf2, HO-1, phosphorylation of p38 and ERK, but down-regulated TLR4 and phosphorylation of p65 NF-κB. Our research recommended that DI ameliorated LPS-induced mastitis which highlights itaconate may as a potential candidate to protect against mastitis.