Sodium butyrate attenuated iE-DAP induced inflammatory response in the mammary glands of dairy goats fed high-concentrate diet

Nutrition, gastrointestinal microorganisms and metabolites in mastitis occurrence and control

Mastitis affects almost all mammals including humans and dairy cows. In the dairy industry, bovine mastitis is a disease with a persistently high incidence, causing serious losses to the health of cows, the quality of dairy products, and the economy of dairy farms. Although local udder infection caused by the invasion of exogenous pathogens into the mammary gland was considered the main cause of mastitis, evidence has been established and continues to grow, showing that nutrition factors and gastrointestinal microbiome (GM) as well as their metabolites are also involved in the development of mammary inflammatory response. Suboptimal nutrition is recognized as a risk factor for increased susceptibility to mastitis in cattle, in particular the negative energy balance. The majority of data regarding nutrition and bovine mastitis involves micronutrients. In addition, the dysbiotic GM can directly trigger or aggravate mastitis through entero-mammary gland pathway. The decreased beneficial commensal bacteria, lowered bacterial diversity, and increased pathogens as well as proinflammatory metabolites are found in both the milk and gastrointestinal tract of mastitic dairy cows. This review discussed the relationship between the nutrition (energy and micronutrient levels) and mastitis, summarized the role of GM and metabolites in regulating mastitis. Meanwhile, several non-antibiotics strategies were provided for the prevention and alleviation of mastitis, including micronutrients, probiotics, short-chain fatty acids, high-fiber diet, inulin, and aryl hydrocarbon receptor.

Subacute ruminal acidosis induces pyroptosis via the mitophagy-mediated NLRP3 inflammasome activation in the livers of dairy cows fed a high-grain diet

High-grain (HG) feeding can trigger subacute ruminal acidosis (SARA) and subsequent liver tissue injury. This study investigated pyroptosis and NLRP3 inflammasome activation in SARA-induced liver injury, and the role of mitophagy during this process. Twelve mid-lactating Holstein cows equipped with rumen fistulas were randomly divided into 2 groups: a low-grain (LG) diet group (grain:forage = 4:6) and a HG diet group (grain:forage = 6:4). Each group had 6 cows. The experiment lasted for 3 wk. The ruminal fluid was collected through the rumen fistula on experimental d 20 and 21, and the pH immediately measured. At the end of the experiment, all animals were slaughtered, and peripheral blood and liver tissue were collected. The ruminal pH was lower in the HG group than that in the LG group at all time points. In addition, the ruminal pH in the HG group was lower than 5.6 at 3 consecutive time points after feeding (4, 6, and 8 h on d 20; 2, 4, and 6 h on d 21), indicating that HG feeding induced SARA. The content of lipopolysaccharide, IL-1β, and apoptosis-related cysteine protease 1 (caspase-1) and the activity of alanine aminotransferase and aspartate aminotransferase in the blood plasma of the HG group were all significantly increased. Hepatic caspase-1 activity was increased in the livers of the HG group. The increased expression levels of pyroptosis- and NLRP3 inflammasome-related genes IL1B, IL18, gasdermin D (GSDMD), apoptosis-associated speck-like protein containing a card (ASC), NLR family pyrin domain-containing 3 (NLRP3), and caspase-1 (CASP1) in liver tissue of the HG group were detected. Furthermore, western blot analysis showed that HG feeding led to increased expression of pyroptosis- and NLRP3 inflammasome-related proteins GSDMD N-terminal (GSDMD-NT), IL-1β, IL-18, cleaved-caspase-1, ASC, NLRP3, and cleaved-caspase-11 and upregulated expression of mitophagy-related proteins microtubule-associated protein 1 light chain 3 II (MAP1LC3-II), beclin 1 (BECN1), Parkin, and PTEN-induced kinase 1 (PINK1) in liver tissue. Collectively, our results revealed that SARA caused increased mitophagy and activated the NLRP3 inflammasome, causing pyroptosis and subsequent liver injury in dairy cows fed a HG diet.

High-concentrate diet elevates histone lactylation mediated by p300/CBP through the upregulation of lactic acid and induces an inflammatory response in mammary gland of dairy cows

High-concentrate diet can cause metabolic diseases, such as subacute ruminal acidosis (SARA), and secondary mastitis. To investigate the effect of SARA induced by high-concentrate diet on the lysine lactylation (Kla) and inflammatory responses in the mammary gland of dairy cows and the mechanism between them, we selected twelve mid-lactation Holstein cows with similar body conditions for modelling. They were randomly divided into two groups, fed a low-concentrate diet (LC) and a high-concentrate diet (HC) for 21 days. Our results showed that high-concentrate diet feeding significantly reduced ruminal pH, and the pH was below 5.6 for more than 3 h per day, indicating successful induction of the SARA model. Lactic acid concentrations in mammary gland and plasma were higher in the HC group than that in the LC group. HC diet feeding significantly up-regulated the expression levels of the Pan Kla, H3K18la, p300/CBP and monocarboxylate transporter 1 (MCT1) in the mammary gland. In addition, the mRNA expression levels of inflammatory factors were significantly regulated, including IL-1β, IL-1α, IL-6, IL-8, SAA3, and TNF-α, while the anti-inflammatory factor IL-10 was down-regulated. The mammary gland of HC group was structurally disorganized with incomplete glandular vesicles, with a large number of detached mammary epithelial cells and inflammatory cells infiltration. The up-regulation of TLR4, TNF-α, p-p65, and p-IκBα indicated that the TLR4/NF-κB signaling pathway was activated. In conclusion, this study found that HC diet feeding can induce SARA and increase the concentration of lactic acid in mammary gland and plasma. Then, lactic acid could be transported into cells by MCT1 and up-regulate the expression level of histone lactylation mediated by p300/CBP, and subsequently promote the activation of TLR4/NF-κB signaling pathway, ultimately causing inflammatory responses in the mammary gland.

Effect of Prepartum Magnesium Butyrate Supplementation on Rumination Time, Milk Yield and Composition, and Blood Parameters in Dairy Cows

Background: Magnesium butyrate (MgB) supplementation of dairy cows during the three-week close-up period was tested for its effects on blood energy analytes, rumination time, inflammation, and lactation performance. Methods: Daily milk yield was recorded and weekly milk samples collected for the first 70 days of lactation from MgB supplemented (MgB, n = 34), and unsupplemented (Control, n = 31) multiparous Holstein-Friesian cows. During a period from week 3 to week 10 postpartum, blood samples were taken and analyzed for various parameters, and ruminant activity was measured. Results: The MgB group yielded 25.2% more milk than the Control during week 1, and had increased milk fat and protein concentrations over a longer duration. Somatic cell counts (SCC) were decreased in the MgB group independent of days in milk. No differences were observed between groups in terms of plasma non-esterified fatty acids, β-hydroxybutyrate, glucose, or blood iCa levels. The MgB group had lower haptoglobin (Hp) levels during lactation relative to the Control group. Time spent ruminating increased after calving with MgB due to a shorter post calving rumination delay relative to the Control group. Conclusions: Prepartum MgB supplementation improved lactation performance without affecting blood energy analytes. The basis by which MgB also improved rumination activity remains to be determined, as DMI could not be assessed. As MgB lowered SCC and Hp concentrations, it is speculated that MgB may help minimize postpartum inflammatory processes.

iE-DAP Induced Inflammatory Response and Tight Junction Disruption in Bovine Mammary Epithelial Cells via NOD1-Dependent NF-κB and MLCK Signaling Pathway

γ-D-glutamyl-meso-diaminopimelic acid (iE-DAP), a bacterial cell wall component, can trigger an inflammatory response. A mammary inflammatory response causes tight junction (TJ) dysfunction. This study aimed to explore the effects and involved mechanisms of iE-DAP-induced inflammatory response on the TJ integrity in bovine mammary epithelial cells (BMECs). The results showed that iE-DAP-induced inflammatory response and TJ disruption was associated with increased expression levels of inflammatory cytokines and decreased gene expression of ZO-1 and Occludin, as well as a reduction in transepithelial electrical resistance and elevation in paracellular dextran passage. While MLCK inhibitor ML-7 reversed the TJ disruption induced by iE-DAP. NF-κB inhibitor BAY 11-7085 hindered the activation of NF-κB and MLCK signaling pathways, the inflammatory response and TJ disruption induced by iE-DAP. NOD1-specific shRNA also inhibited the activation of the NOD1/NF-κB signaling pathway and reversed the inflammatory response and TJ injury in iE-DAP-treated BMECs. Above results suggest that iE-DAP activated the NF-κB and MLCK signaling pathway in NOD1-dependent manner, which promoted the transcription of inflammatory cytokines and altered the expression and distribution of tight junction proteins, finally caused inflammatory response and TJ disruption. This study might provide theoretical basis and scientific support for the prevention and treatment of mastitis.

High concentrate diet induced inflammatory response and tight junction disruption in the mammary gland of dairy cows

This study aimed to investigate the effect and mechanism of a high concentrate (HC) diet on the inflammatory response and cellular tight junctions (TJs) in the mammary gland of dairy cows. Twelve lactating Holstein dairy cows were randomly assigned into low concentrate (LC) and HC groups (n = 6), which were fed with LC diet and HC diet respectively for 3 weeks. The HC diet lead to subacute ruminant acidosis with a rumen pH < 5.6 more than 3 h daily. The HC diet triggered an inflammatory response with increased levels of inflammatory cytokines in the lacteal vein, upregulated expression of inflammation-related genes, elevated activity of myeloperoxidase, and inflammatory cells infiltration in the mammary gland. Furthermore, the HC diet induced the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways with enhanced phosphorylation ratios of NF-κB P65, inhibitor of NF-κB (IκB), P38 and extracellular signal-regulated kinase 1/2 (ERK1/2) as well as decreased ratios of DNA methylation and chromatin compaction of genes coding for proinflammatory cytokines, which contributed to the upregulation of proinflammatory cytokine expression. The HC diet also destroyed the integrity of TJ with discontinuous and decreased expression levels of zonula occludens-1, Occludin, Claudin-4 and increased expression level of Claudin-1 in the mammary epithelial cells compared with LC group. Conclusively, the HC diet induced the activation of NF-κB and MAPK signaling pathways and epigenetic modifications, promoted the transcription of proinflammatory cytokines, and finally caused inflammatory response and TJ disruption in the mammary gland of dairy cows.

A high-concentrate diet induces inflammatory injury via regulating Ca2+/CaMKKβ-mediated autophagy in mammary gland tissue of dairy cows

Introduction

Calmodulin-dependent protein kinase β (CaMKKβ) is closely related to Ca²⁺ concentration. An increase in Ca²⁺ concentration in the cytoplasm activates CaMKKβ, and activated CaMKKβ affects the activities of AMPK and mTOR and induces autophagy. A high-concentrate diet leads to Ca²⁺ disorder in mammary gland tissue.

Objectives

Therefore, this study mainly investigated the induction of mammary gland tissue autophagy by a high-concentrate diet and the specific mechanism of lipopolysaccharide (LPS)-induced autophagy in bovine mammary epithelial cells (BMECs).

Material and Methods

Twelve mid-lactation Holstein dairy cows were fed with a 40% concentrate diet (LC) and a 60% concentrate diet (HC) for 3 weeks. At the end of the trial, rumen fluid, lacteal vein blood, and mammary gland tissue were collected. The results showed that the HC diet significantly decreased rumen fluid pH, with a pH lower than 5.6 for more than 3 h, indicating successfully induction of subacute rumen acidosis (SARA). The mechanism of LPS-induced autophagy in BMECs was studied in vitro. First, the cells were divided into a Ctrl group and LPS group to study the effects of LPS on the concentration of Ca²⁺ and autophagy in BMECs. Then, cells were pretreated with an AMPK inhibitor (compound C) or CaMKKβ inhibitor (STO-609) to investigate whether the CaMKKβ-AMPK signaling pathway is involved in LPS-induced BMEC autophagy.

Results

The HC diet increased the concentration of Ca²⁺ in mammary gland tissue and pro-inflammatory factors in plasma. The HC diet also significantly increased the expression of CaMKKβ, AMPK, and autophagy-related proteins, resulting in mammary gland tissue injury. In vitro cell experiments showed that LPS increased intracellular Ca²⁺ concentration and upregulated protein expression of CaMKKβ, AMPK, and autophagy-related proteins. Compound C pretreatment decreased the expression of proteins related to autophagy and inflammation. In addition, STO-609 pretreatment not only reversed LPS-induced BMECs autophagy but also inhibited the protein expression of AMPK, thereby alleviating the inflammatory response in BMECs. These results suggest that inhibition of the Ca²⁺/CaMKKβ-AMPK signaling pathway reduces LPS-induced autophagy, thereby alleviating inflammatory injury of BMECs.

Conclusion

Therefore, SARA may increase the expression of CaMKKβ by increasing Ca²⁺ levels and activate autophagy through the AMPK signaling pathway, thereby inducing inflammatory injury in mammary gland tissue of dairy cows.

M6A RNA Methylation Mediates NOD1/NF-kB Signaling Activation in the Liver of Piglets Challenged with Lipopolysaccharide

N⁶-methyladenosine (m⁶A) is the most abundant internal modification that widely participates in various immune and inflammatory responses; however, its regulatory mechanisms in the inflammation of liver induced by lipopolysaccharide in piglets remain largely unknown. In the present study, piglets were intraperitoneally injected with 80 μg/kg LPS or an equal dose of sterile saline. Results indicated that LPS administration increased activities of serum alanine aminotransferase (ALT), induced M1 macrophage polarization and promoted secretion of inflammatory cytokines, and finally led to hepatic lesions in piglets. The NOD1/NF-κB signaling pathway was activated in the livers of the LPS group. Moreover, the total m⁶A level was significantly elevated after LPS treatment. MeRIP-seq showed that 1166 and 1344 transcripts contained m⁶A methylation in control and LPS groups, respectively. The m⁶A methylation sites of these transcripts mainly distributes in the 5′ untranslated region (5′UTR), the coding sequence (CDS), and the 3′ untranslated region (3′UTR). Interestingly, these genes were mostly enriched in the NF-κB signaling pathway, and LPS treatment significantly changed the m⁶A modification in NOD1, RIPK2, NFKBIA, NFKBIB, and TNFAIP3 mRNAs. In addition, knockdown of METTL3 or overexpression of FTO both changed gene levels in the NOD1/NF-κB pathway, suggesting that activation of this pathway was regulated by m⁶A RNA methylation. Moreover, the alteration of m⁶A RNA methylation profile may be associated with the increase of reactive oxygen species (ROS), HIF-1α, and MAT2A. In conclusion, LPS activated the NOD1/NF-κB pathway at post-transcriptional regulation through changing m⁶A RNA methylation, and then promoted the overproduction of proinflammatory cytokines, ultimately resulting in liver inflammation and damage.

The Role of Rumen Microbiota and Its Metabolites in Subacute Ruminal Acidosis (SARA)-Induced Inflammatory Diseases of Ruminants

Subacute ruminal acidosis (SARA) is a common metabolic disease in ruminants. In the early stage of SARA, ruminants do not exhibit obvious clinical symptoms. However, SARA often leads to local inflammatory diseases such as laminitis, mastitis, endometritis and hepatitis. The mechanism by which SARA leads to inflammatory diseases is largely unknown. The gut microbiota is the totality of bacteria, viruses and fungi inhabiting the gastrointestinal tract. Studies have found that the gut microbiota is not only crucial to gastrointestinal health but also involved in a variety of disease processes, including metabolic diseases, autoimmune diseases, tumors and inflammatory diseases. Studies have shown that intestinal bacteria and their metabolites can migrate to extraintestinal distal organs, such as the lung, liver and brain, through endogenous pathways, leading to related diseases. Combined with the literature, we believe that the dysbiosis of the rumen microbiota, the destruction of the rumen barrier and the dysbiosis of liver function in the pathogenesis of SARA lead to the entry of rumen bacteria and/or metabolites into the body through blood or lymphatic circulation and place the body in the "chronic low-grade" inflammatory state. Meanwhile, rumen bacteria and/or their metabolites can also migrate to the mammary gland, uterus and other organs, leading to the occurrence of related inflammatory diseases. The aim of this review is to describe the mechanism by which SARA causes inflammatory diseases to obtain a more comprehensive and profound understanding of SARA and its related inflammatory diseases. Meanwhile, it is also of great significance for the joint prevention and control of diseases.

A high-concentrate diet provokes inflammatory responses by downregulating Forkhead box protein A2 (FOXA2) through epigenetic modifications in the liver of dairy cows

A high-concentrate diet has been reported to promote an inflammatory response in dairy cows. The purpose of this study was to clarify the effect of the high-concentrate (HC) diet on hepatic Forkhead box protein A2 (FOXA2) expression and uncover the molecular mechanisms in inflammatory responses in the liver. The results showed that the HC diet reduced the ruminal fluid pH and elevated the secretion of SAA3, IL-1α, and IL-8 and reduced that of IL-10 in peripheral blood plasma. Compared with the low-concentrate (LC) group, the concentration of myeloperoxidase (MPO) was higher in the liver of dairy cows in the HC group. In addition, the relative mRNA expression of acute phase proteins (HP, SAA3, and LBP), proinflammatory cytokines (TNFα, IL-1α, IL-1β, IL-8), TLR4, MyD88, TRAF6, TRIF, IκBα, p65, p38 and JNK1 was upregulated and that of IL-10 was downregulated in the liver of the HC group. Consistently, the protein abundance of TLR4, TNFα and phosphorylation of proteins involved in NF-κB (IκBα and p65) and MAPK (p38 and JNK) pathways were significantly increased in the HC group compared with the LC group. And both the mRNA and protein abundance of FOXA2 were downregulated in the HC group. Further epigenetic analysis results demonstrated that chromatin compaction and DNA hypermethylation contributed to inhibiting FOXA2 expression, in which the demethylase ten-eleven translocation 1 (TET1) and histone deacetylase 3 (HDAC3) might participate. Overall, these findings demonstrated that the high-concentrate diet triggered inflammatory cascades and downregulated FOXA2 by epigenetic modifications in the liver of dairy cows.

Sodium Butyrate More Effectively Mitigates the Negative Effects of High-Concentrate Diet in Dairy Cows than Sodium β-Hydroxybutyrate via Reducing Free Bacterial Cell Wall Components in Rumen Fluid and Plasma

The present study was aimed at investigating the effects of sodium butyrate and sodium β-hydroxybutyrate on lactation and health of dairy cows fed a high-concentrate (HC) diet. Eighty mid-lactation dairy cows with an average milk yield of 33.75 ± 5.22 kg/d were randomly allocated to four groups (n = 20 per group) and were fed either a low-concentrate (LC) diet, a HC diet, the HC diet with 1% sodium butyrate (HCSB), or the HC diet with 1% sodium β-hydroxybutyrate (HCHB). The feeding trial lasted for 7 weeks, with a 2-week adaptation period and a 5-week measurement period, and the trial started from 96 ± 13 d in milk. Sodium butyrate supplementation delayed the decline in milk production and improved milk synthesis efficiency and milk fat content. Additionally, it decreased the proinflammatory cytokines and acute phase proteins (APPs) in plasma, the leucocytes in blood, the somatic cell count (SCC) in milk, and the gene expression of pattern recognition receptors (PRRs) and proinflammatory cytokines in the mammary gland, due to decreasing the contents of bacterial cell wall components (lipopolysaccharide, LPS; peptidoglycan, PGN; and lipoteichoic acid, LTA) in the rumen and plasma, compared with the HC diet. Sodium β-hydroxybutyrate supplementation also improved milk yield, milk synthesis efficiency and milk fat content and partially reduced the adverse effects caused by the HC diet, but it had no effect on decreasing bacterial cell wall components in the rumen and plasma, compared with the HC diet. Collectively, both sodium butyrate and sodium β-hydroxybutyrate mitigated the negative effects of HC diet on lactation and health of dairy cows, with sodium butyrate being more effective than sodium β-hydroxybutyrate.