Stromal fibroblasts derived from mammary gland of bovine with mastitis display inflammation-specific changes

Beta-Glucans Improve the Mammary Innate Immune Response to Endotoxin Challenge in Dairy Ewes

This study evaluated short-term immune responses of dairy ewes supplemented with barley β-glucan (BG) following an intramammary Escherichia coli lipopolysaccharide (LPS) challenge. In the adaptation period, 36 ewes were fed an alfalfa hay diet ad libitum and barley grain cv. Hispanic (3.8% BG). Then, ewes were assigned into three experimental groups: (1) Control (CON), the same previous diet (13.3 g BG/d); (2) high β-glucans barley (HBG), new barley (cv. Annapurna) containing 10% BG (35 g BG/d); (3) intraperitoneally injected (INP) with a 1.4% BG solution dose (2 g BG/ewe). At d 9, all ewes were infused with an E. coli LPS or saline solution in each udder half. After the challenge, rectal temperature (RT), milk yield and composition, somatic cell count (SCC), and plasma interleukins (IL-1α and IL-1β) were monitored daily. The INP treatment revealed a transitory increase in RT and decreased milk yield by 38%. Milk fat, protein, and SCC increased in LPS-treated udders but not by BG treatment. The IL-1α plasma concentration was similar among groups but INP ewes showed a lower IL-1β concentration suggesting a lower inflammatory response. The BG administration appears more effective intraperitoneally than orally, which needs additional study.

Lespedeza bicolor Turcz. Honey Prevents Inflammation Response and Inhibits Ferroptosis by Nrf2/HO-1 Pathway in DSS-Induced Human Caco-2 Cells

Lespedeza bicolor Turcz. (L. bicolor) honey, a monofloral honey, has garnered increased attention due to its origin in the L. bicolor plant. A previous study has shown that L. bicolor honey can ameliorate inflammation. In this study, we aimed to investigate the effects of L. bicolor honey extract and its biomarker (Trifolin) on DSS-induced ulcerative colitis (UC). Our results demonstrated that L. bicolor honey extract and Trifolin significantly increased the expression levels of the tight junction cytokines Claudin-1 and ZO-1. Additionally, they decreased the pro-inflammatory factors TNF-α and IL-6 and enhanced the antioxidant factors NQO1 and GSTA1. Based on metabolomic analyses, L. bicolor honey extract and Trifolin regulated the progression of UC by inhibiting ferroptosis. Mechanistically, they improved the levels of SOD and iron load, increased the GSH/GSSG ratio, reduced MDA content and ROS release, and upregulated the Nrf2/HO-1 pathway, thereby inhibiting DSS-induced UC. Moreover, the expression levels of ferroptosis-related genes indicated that they decreased FTL, ACSL4, and PTGS2 while increasing SLC7A11 expression to resist ferroptosis. In conclusion, our study found that L. bicolor honey improves DSS-induced UC by inhibiting ferroptosis by activating the Nrf2/HO-1 pathway. These findings further elucidate the understanding of anti-inflammatory and antioxidant activities of L. bicolor honey.

Going Full TeRM: The Seminal Role of Tissue-Resident Macrophages in Organ Remodeling during Pregnancy and Lactation

During pregnancy and lactation, the uterus and mammary glands undergo remarkable structural changes to perform their critical reproductive functions before reverting to their original dormant state upon childbirth and weaning, respectively. Underlying this incredible plasticity are complex remodeling processes that rely on coordinated decisions at both the cellular and tissue-subunit levels. With their exceptional versatility, tissue-resident macrophages play a variety of supporting roles in these organs during each stage of development, ranging from maintaining immune homeostasis to facilitating tissue remodeling, although much remains to be discovered about the identity and regulation of individual macrophage subsets. In this study, we review the increasingly appreciated contributions of these immune cells to the reproductive process and speculate on future lines of inquiry. Deepening our understanding of their interactions with the parenchymal or stromal populations in their respective niches may reveal new strategies to ameliorate complications in pregnancy and breastfeeding, thereby improving maternal health and well-being.

Transcriptional Profiling Reveals the Wheat Defences against Fusarium Head Blight Disease Regulated by a NAC Transcription Factor

The wheat NAC transcription factor TaNACL-D1 enhances resistance to the economically devastating Fusarium head blight (FHB) disease. The objective of this study was to decipher the alterations in gene expression, pathways and biological processes that led to enhanced resistance as a result of the constitutive expression of TaNACL-D1 in wheat. Transcriptomic analysis was used to determine the genes and processes enhanced in wheat due to TaNACL-D1 overexpression, both in the presence and absence of the causal agent of FHB, Fusarium graminearum (0- and 1-day post-treatment). The overexpression of TaNACL-D1 resulted in more pronounced transcriptional reprogramming as a response to fungal infection, leading to the enhanced expression of genes involved in detoxification, immune responses, secondary metabolism, hormone biosynthesis, and signalling. The regulation and response to JA and ABA were differentially regulated between the OE and the WT. Furthermore, the results suggest that the OE may more efficiently: (i) regulate the oxidative burst; (ii) modulate cell death; and (iii) induce both the phenylpropanoid pathway and lignin synthesis. Thus, this study provides insights into the mode of action and downstream target pathways for this novel NAC transcription factor, further validating its potential as a gene to enhance FHB resistance in wheat.

Comprehensive Analysis of lncRNA and mRNA Expression Profile of Macrophage RAW264.7 Stimulated by Antimicrobial Peptide BSN-37

BACKGROUND

BSN-37, a novel antimicrobial peptide (AMP) containing 37 amino acid residues isolated from the bovine spleen, has not only antibacterial activity but also immunomodulatory activity. Recent evidence shows that long non-coding RNAs (lncRNAs) play an important role in regulating the activation and function of immune cells. The purpose of this experiment was to investigate the lncRNA and mRNA expression profile of mouse macrophages RAW264.7 stimulated by bovine antimicrobial peptide BSN-37.

METHODS

The whole gene expression microarray was used to detect the differentially expressed lncRNA and mRNA between antimicrobial peptide BSN-37 activated RAW264.7 cells and normal RAW264.7 cells. KEGG pathway analysis and GO function annotation analysis of differentially expressed lncRNAs and mRNA were carried out. Eight kinds of lncRNAs and nine kinds of mRNA with large differences were selected for qRT-PCR verification, respectively.

RESULTS

In the current study, we found that 1294 lncRNAs and 260 mRNAs were differentially expressed between antibacterial peptide BSN-37 treatment and control groups. Among them, Bcl2l12, Rab44, C1s, Cd101 and other genes were associated with immune responses and were all significantly up-regulated. Mest and Prkcz are related to cell growth, and other genes are related to glucose metabolism and lipid metabolism. In addition, some immune-related terms were also found in the GO and KEGG analyses. At the same time, real-time quantitative PCR was used to verify selected lncRNA and mRNA with differential expression. The results of qRT-PCR verification were consistent with the sequencing results, indicating that our data were reliable.

CONCLUSION

This study provides the lncRNA and mRNA expression profiles of RAW264.7 macrophages stimulated by antimicrobial peptide BSN-37 and helps to provide a reference value for subsequent studies on lncRNA regulation of antimicrobial peptide BSN-37 immune function.

The NLRP3 Activation in Infiltrating Macrophages Contributes to Corneal Fibrosis by Inducing TGF-β1 Expression in the Corneal Epithelium

Purpose

To explore the effect and mechanism of NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasomes on corneal fibrosis.

Methods

The wild-type, NLRP3 knockout (KO), and myeloid cell-specific NLRP3 KO (NLRP3 Lyz-KO) C57 mice were used to establish a corneal scarring model. NLRP3 inhibitor, IL-1β neutralizing antibody, and an IL-1R antagonist were used to investigate the role of NLRP3 and IL-1β in corneal fibrosis. The expression of the NLRP3 signaling pathway related proteins, alpha-smooth muscle actin, TGF-β was determined by quantitative real-time polymerase chain reaction, Western blotting, and immunofluorescence staining. Flow cytometry was used to detect the infiltration of macrophages during corneal fibrosis.

Results

The components of the NLRP3 inflammasomes were elevated and activated during corneal scarring. Additionally, genetic or chemical-mediated blocking of NLRP3 as well as IL-1β significantly alleviated corneal fibrosis. Moreover, neutrophil (CD45⁺Ly6G⁺) and macrophage (CD45⁺ F4/80⁺) accumulation increased in the cornea during the progression of corneal fibrosis. Intriguingly, the increased concentrations of NLRP3 and IL-1β were prominently colocalized with the infiltrating F4/80⁺ macrophages. Expectedly, NLRP3 Lyz-KO mice exhibited a marked decrease in their corneal fibrosis symptoms. Mechanistically, the activation of IL-1β or macrophage NLRP3 stimulated the expression of TGF-β1 in the corneal epithelial cells, whereas an NLRP3 deficiency decreased its expression in the corneal epithelium.

Conclusions

These observations revealed that the NLRP3 inflammasome activation in infiltrating macrophages contributes to corneal fibrosis by regulating corneal epithelial TGF-β1 expression. Targeting the NLRP3 inflammasome might be a promising strategy for the treatment of corneal scarring.

Genome-Wide Association Studies for Milk Somatic Cell Score in Romanian Dairy Cattle

Mastitis is one of the most frequently encountered diseases in dairy cattle, negatively affecting animal welfare and milk production. For this reason, contributions to understanding its genomic architecture are of great interest. Genome-wide association studies (GWAS) have identified multiple loci associated with somatic cell score (SCS) and mastitis in cattle. However, most of the studies have been conducted in different parts of the world on various breeds, and none of the investigations have studied the genetic architecture of mastitis in Romanian dairy cattle breeds up to this point in time. In this study, we report the first GWAS for SCS in dairy cattle breeds from Romania. For GWAS, we used an Axiom Bovine v3 SNP-chip (>63,000 Single Nucleotide Polymorphism -SNPs) and 33,330 records from 690 cows belonging to Romanian Spotted (RS) and Romanian Brown (RB) cattle. The results found one SNP significantly associated with SCS in the RS breed and 40 suggestive SNPs with -log₁₀ (p) from 4 to 4.9 for RS and from 4 to 5.4 in RB. From these, 14 markers were located near 12 known genes (AKAP8, CLHC1, MEGF10, SATB2, GATA6, SPATA6, COL12A1, EPS8, LUZP2, RAMAC, IL12A and ANKRD55) in RB cattle, 3 markers were close to ZDHHC19, DAPK1 and MMP7 genes, while one SNP overlapped the HERC3 gene in RS cattle. Four genes (HERC3, LUZP2, AKAP8 and MEGF10) associated with SCS in this study were previously reported in different studies. The most significant SNP (rs110749552) associated with SCS was located within the HERC3 gene. In both breeds, the SNPs and position of association signals were distinct among the three parities, denoting that mastitis is controlled by different genes that are dependent according to parity. The current results contribute to an expansion in the body of knowledge regarding the proportion of genetic variability explained by SNPs for SCS in dairy cattle.

Omega-3 polyunsaturated fatty acids ameliorated inflammatory response of mammary epithelial cells and mammary gland induced by lipopolysaccharide

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), essential fatty acids for humans and animals, have been reported to play a beneficial role in a variety of inflammatory diseases. In this study, we investigated the inhibitory effects and potential molecular mechanisms of n-3 PUFAs on the inflammatory response in lipopolysaccharide (LPS)-stimulated mammary alveolar cell line (MAC-T). Results showed that n-3 PUFAs could abate LPS-induced secretions of tumor necrosis factor-α, interleukin (IL)-6 and IL-1β in MAC-T cells through the nuclear transcription factor kappa B (NF-κB) signal pathway. Meanwhile, n-3 PUFA intervention attenuated histopathologic changes of mammary glands, the white blood cell number decrease, and the alkaline phosphatase level decrease in the serum of mice challenged by LPS. Furthermore, n-3 PUFA intervention improved the ecological structure of the flora in terms of the structural disorder of the non-significant dominant flora induced by LPS in mice. Collectively, both in vitro and in vivo experiments revealed that n-3 PUFAs have a positive effect on LPS-induced inflammatory response, which was possibly mediated by the NF-κB signaling pathway and the intestinal microbiota.

Hederacoside-C Inhibition of Staphylococcus aureus-Induced Mastitis via TLR2 & TLR4 and Their Downstream Signaling NF-κB and MAPKs Pathways In Vivo and In Vitro

Hederacoside-C (HDC) is a biological active ingredient, extracted from the leaves of Hedera helix. It has been reported to have anti-inflammatory properties. However, the effects of HDC on Staphylococcus aureus (S. aureus)-induced mastitis have not been reported yet. Here, we evaluated the anti-inflammatory effects of HDC on S. aureus-induced mastitis both in vivo on mammary gland tissues and in vitro on RAW 264.7 cells. The ascertained histopathological changes and MPO activity revealed that HDC defended mammary glands from tissue destruction and inflammatory cell infiltration induced by S. aureus. The results of ELISA, western blot, and qRT-PCR indicated that HDC significantly inhibited the expressions IL-6, IL-1β, and TNF-α and enhanced the IL-10 by downregulating and upregulating their relevant genes, respectively. Furthermore, HDC markedly suppressed the TLR2 and TLR4 expressions by attenuating the MAPKs (p38, ERK, JNK) and NF-κB (p65 and IκBα) pathways followed by decreasing the phosphorylation of p38, ERK, JNK, p65, and IκBα. The above parameters enhanced the mammary gland defense and reduced inflammation. These findings suggested that HDC may have the potential to be an effective anti-inflammatory drug for the S. aureus-induced mice mastitis and in RAW 264.7 cells.

Genomic Identification, Evolution, and Expression Analysis of Collagen Genes Family in Water Buffalo during Lactation

Collagens, as extracellular matrix proteins, support cells for structural integrity and contribute to support mammary basic structure and development. This study aims to perform the genomic identification, evolution, and expression analyses of the collagen gene family in water buffalo (Bubalus bubalis) during lactation. A total of 128 buffalo collagen protein sequences were deduced from the 45 collagen genes identified in silico from buffalo genome, which classified into six groups based on their phylogenetic relationships, conserved motifs, and gene structure analyses. The identified collagen sequences were unequally distributed on 16 chromosomes. The tandem duplicated genes were found within three chromosomes, while only one segmental event occurred between Chr3 and Chr8. Collinearity analysis revealed that a total of 36 collagen gene pairs were orthologous between buffalo and cattle genomes despite having different chromosome numbers. Comparative transcription analyses revealed that a total of 23 orthologous collagen genes were detected in the milk samples at different lactation periods between the two species. Notably, the duplicated gene pair of COL4A1-COL4A2 during lactation had a higher mRNA expression level than that of cattle, while a higher expression level of COL6A1-COL6A2 pair was found in cattle compared with that of buffalo. The present study provides useful information for investigating the potential functions of the collagen family in buffalo during lactation and helps in the functional characterization of collagen genes in additional research.

LRRC75A antisense lncRNA1 knockout attenuates inflammatory responses of bovine mammary epithelial cells

Long noncoding RNAs (lncRNAs) play multiple key roles during inflammatory processes. In this study, a novel lncRNA identified by the high-throughput sequencing analysis was found significantly down-regulated in Escherichia coli-introduced cell model of bovine mastitis. Given that this lncRNA consists of the antisense of leucine-rich repeat-containing protein 75A (LRRC75A), it was named LRRC75A antisense lncRNA1 (LRRC75A-AS1). The expression of LRRC75A-AS1 was down-regulated in bovine mammary epithelial cells and mammary tissues under inflammatory condition. Knockout (KO) of LRRC75A-AS1 by CRISPR-Cas9 system in bovine mammary alveolar cell-T (MAC-T) cell line could enhance expressions of tight junction (TJ) proteins Claudin-1, Occludin and ZO-1, reduce cell monolayer permeability, and inhibit Staphylococcus aureus adhesion and invasion. Meanwhile, it also down-regulated expressions of inflammatory factors and attenuated activation of NF-κB pathway. Similarly, knockdown of LRRC75A caused the changes as LRRC75A-AS1 KO did, while overexpression of LRRC75A enabled the opposite effects. TJ of epithelioid cells barriers the pathogenic microorganisms outside during inflammation, in which LRRC75A-AS1 can regulate the expression of TJ proteins through LRRC75A, affecting the development of inflammation.

Digital gene expression analyses of mammary glands from meat ewes naturally infected with clinical mastitis

Clinical mastitis in sheep has gravely restrained production performance for a long time. Knowledge of mechanisms of its pathogenesis and resistance in meat sheep mammary gland with clinical mastitis are not yet understood, especially for clinical mastitis caused by natural infection. In this work, RNA-sequencing was firstly used to screen the differentially expressed genes (DEGs) in clinical mastitic mammary tissues (CMMTs) when compared with healthy mammary tissues (HMTs) from meat sheep flocks. We identified 420 DEGs including 316 upregulated and 104 downregulated genes in CMMTs. Gene ontology annotation revealed these DEGs were mainly engaged in immune response and inflammation response. Pathway enrichment showed they were primarily enriched in pathways relevant to inflammation, immune response and metabolism. Alternative splicing analysis showed most common differential splicing genes in CMMTs and HMTs were implicated in immune response. Immunostaining for three immune response-related proteins encoded by DEGs were mainly observed in mammary epithelium from both CMMTs and HMTs, and their positive signals were more intensive in CMMTs than those in HMTs. These findings provide experimental basis and reference for further researching the molecular genetic mechanisms, particularly immune defence mechanisms, of sheep mammary gland during clinical mastitis.

A novel long non-coding RNA regulates the immune response in MAC-T cells and contributes to bovine mastitis

The long non-coding RNAs (lncRNAs) are known to transcriptionally regulate a wide spectrum of diseases. Here, we screened for potentially functional lncRNAs in a mammary epithelial cell model of bovine mastitis by RNA-Seq technology and identified a class of previously undetected mastitis-related lncRNAs. A novel lncRNA was widely expressed in a variety of bovine tissues with diverse relative abundance and had a relatively low expression in mammary tissue. Given its predicted target gene is TUBA1C, we name it lncRNA-TUB. We found a higher expression of lncRNA-TUB in mammary epithelial cells that received a proinflammatory stimulus compared to normal cells. Knockout of lncRNA-TUB by the CRISPR/Cas9 system revealed that it plays crucial roles in the morphological shape, proliferation, migration and β-casein secretion of mammary epithelial cells. In addition, lncRNA-TUB mediates Escherichia coli-induced inflammatory factor secretion and Staphylococcus aureus adhesion to epithelial cells. Our results suggest that the lncRNAs identified here function in bovine mastitis, and that lncRNA-TUB affects the basic biological characteristics and functions of bovine mammary epithelial cells in inflammatory conditions, providing valuable insights into the mechanisms of bovine mastitis.

NDRG1 negatively regulates proliferation and Milk bio-synthesis of bovine epithelial cells via the mTOR signaling pathway

The expression of N-myc downstream-regulated gene 1 (NDRG1) was significantly correlated with diverse processes such as cell growth and differentiation, lipid synthesis, stress and immune responses. Here we explored the role of NDRG1 expression in bovine mammary tissue and epithelial cells under an inflammatory condition. Results showed that NDRG1 expression was elevated in bovine mammary tissue with mastitis and mammary epithelial cells treated by heat inactivated Escherichia coli and Staphylococcus aureus compared to normal tissue and untreated cells. Overexpression of NDRG1 significantly inhibited cell proliferation and migration, β-casein secretion, gene expressions of inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-6 and IL-8, and activation of mTOR signal pathway of mammary epithelial cells, and vice versa by NDRG1 knockdown. These findings suggest that NDRG1 has immense potential in the regulation of properties in bovine mammary epithelial cells under an inflammatory condition.

MCPIP1 mediates inflammatory responses induced by lipopolysaccharide and lipoteichoic acid in bovine mammary epithelial cells

Monocyte chemoattractant protein-induced protein 1 (MCPIP1) is a kind of zinc finger RNA binding protein, which exerts immune responses in a variety of cell types. However, the role of MCPIP1 in bovine mammary epithelial cells during mastitis has not been studied. In this study, we explored the functions of MCPIP1 in the inflammatory process induced by virulence factors of pathogens in bovine mammary alveolar cell-T (MAC-T) cell line. Our results showed that MCPIP1 was significantly highly expressed both in the mammary tissue of dairy cows with mastitis and in inflammatory MAC-T cells induced by lipopolysaccharide (LPS) or lipoteichoic acid (LTA). Furthermore, we found that overexpression of MCPIP1 in MAC-T cells abated the LPS-induced increase at the gene expression levels of inflammatory mediators tumor necrosis factor-α-α, interleukin (IL)-1β, IL-6 and IL-8, enhanced the LPS- and LTA-induced inhibition of epithelial proliferation and promoted the LPS- and LTA-induced oxidative and DNA damage. These findings indicated that MCPIP1 has an enormous potential in regulating the inflammatory response of bovine mammary epithelial cells during infection and may provide an effective therapeutic target for bovine mastitis to reduce the damage caused by inflammatory reactions.

AMPK/PGC1α activation by melatonin attenuates acute doxorubicin cardiotoxicity via alleviating mitochondrial oxidative damage and apoptosis

Doxorubicin (DOX) is a highly effective anticancer anthracycline drug, but its side effects at the level of the heart has limited its widespread clinical application. Melatonin is a documented potent antioxidant, nontoxic and cardioprotective agent, and it is involved in maintaining mitochondrial homeostasis and function. The present study established acute DOX-induced cardiotoxicity models in both H9c2 cells incubated with 1 μM DOX and C57BL/6 mice treated with DOX (20 mg/kg cumulative dose). Melatonin markedly alleviated the DOX-induced acute cardiac dysfunction and myocardial injury. Both in vivo and in vitro studies verified that melatonin inhibited DOX-induced mitochondrial dysfunction and morphological disorders, apoptosis, and oxidative stress via the activation of AMPK and upregulation of PGC1α with its downstream signaling (NRF1, TFAM and UCP2). These effects were reversed by the use of AMPK siRNA or PGC1α siRNA in H9c2 cells, and were also negated by the cotreatment with AMPK inhibitor Compound C in vivo. Moreover, PGC1α knockdown was without effect on the AMPK phosphorylation induced by melatonin in the DOX treated H9c2 cells. Therefore, AMPK/PGC1α pathway activation may represent a new mechanism for melatonin exerted protection against acute DOX cardiotoxicity through preservation of mitochondrial homeostasis and alleviation of oxidative stress and apoptosis.

LncRNA XIST mediates bovine mammary epithelial cell inflammatory response via NF-κB/NLRP3 inflammasome pathway

Objectives

The correlations between long non‐coding RNAs (lncRNAs) and diverse mammal diseases have been clarified by many researches, but the cognition about bovine mastitis‐related lncRNAs remains limited. This study aimed to investigate the potential role of lncRNA X‐inactive specific transcript (XIST) in the inflammatory response of bovine mammary epithelial cells.

Materials and methods

Two inflammatory bovine mammary alveolar cell‐T (MAC‐T) models were established by infecting the cells with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The expressions of pro‐inflammatory cytokines were measured, and the proliferation, viability and apoptosis of the inflammatory cells were evaluated after XIST was knocked down by an siRNA. The relationship among XIST, NF‐κB pathway and NOD‐like receptor protein 3 (NLRP3) inflammasome was investigated using an inhibitor of NF‐κB signal pathway.

Results

The expression of XIST was abnormally increased in bovine mastitic tissues and inflammatory MAC‐T cells. Silencing of XIST significantly increased the expression of E. coli or S. aureus‐induced pro‐inflammatory cytokines. Additionally, knockdown of XIST could inhibit cell proliferation, suppress cell viability and promote cell apoptosis under inflammatory conditions. Furthermore, XIST inhibited E. coli or S. aureus‐induced NF‐κB phosphorylation and the production of NLRP3 inflammasome.

Conclusions

The expression of XIST was promoted by activated NF‐κB pathway and, in turn, XIST generated a negative feedback loop to regulate NF‐κB/NLRP3 inflammasome pathway for mediating the process of inflammation.

HDAC1/2-mediated regulation of JNK and ERK phosphorylation in bovine mammary epithelial cells in response to TNF-α

Bovine mammary epithelial cells (MAC-Ts) are a common cell line for the study of mammary epithelial inflammation; these cells are used to mechanistically elucidate molecular underpinnings that contribute to bovine mastitis. Bovine mastitis is the most prevalent form of disease in dairy cattle that culminates in annual losses of two billion dollars for the US dairy industry. Thus, there is an urgent need for improved therapeutic strategies. Histone deacetylase (HDAC) inhibitors are efficacious in rodent models of inflammation, yet their role in bovine mammary cells remain unclear. HDACs have traditionally been studied in the regulation of nucleosomal DNA, in which deacetylation of histones impact chromatin accessibility and gene expression. Using MAC-T cells stimulated with tumor necrosis factor α (TNF-α) as a model for mammary cell inflammation, we report that inhibition of HDACs1 and 2 (HDAC1/2) attenuated TNF-α-mediated inflammatory gene expression. Of note, we report that HDAC1/2-mediated inflammatory gene expression was partly regulated by c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) phosphorylation. Here, we report that HDAC1/2 inhibition attenuated JNK and ERK activation and thus inflammatory gene expression. These data suggest that HDACs1 and 2 regulate inflammatory gene expression via canonical (i.e., gene expression) and noncanonical (e.g., signaling dependent) mechanisms. Whereas, further studies using primary cell lines and animal models are needed. Our combined data suggest that HDAC1/2-specific inhibitors may prove efficacious for the treatment of bovine mastitis.

Genome-wide association study for milking speed in French Holstein cows

Using a combination of data from the BovineSNP50 BeadChip SNP array (Illumina, San Diego, CA) and a EuroGenomics (Amsterdam, the Netherlands) custom single nucleotide polymorphism (SNP) chip with SNP pre-selected from whole genome sequence data, we carried out an association study of milking speed in 32,491 French Holstein dairy cows. Milking speed was measured by a score given by the farmer. Phenotypes were yield deviations as obtained from the French evaluation system. They were analyzed with a linear mixed model for association studies. We identified SNP on 22 chromosomes significantly associated with milking speed. As clinical mastitis and somatic cell score have an unfavorable genetic correlation with milking speed, we tested whether the most significant SNP on these 22 chromosomes associated with milking speed were also associated with clinical mastitis or somatic cell score. Nine hundred seventy-one genome-wide significant SNP were associated with milking speed. Of these, 86 were associated with clinical mastitis and 198 with somatic cell score. The most significant association signals for milking speed were observed on chromosomes 7, 8, 10, 14, and 18. The most significant signal was located on chromosome 14 (ZFAT gene). Eleven novel milking speed quantitative trait loci (QTL) were observed on chromosomes 7, 10, 11, 14, 18, 25, and 26. Twelve candidate SNP for milking speed mapped directly within genes. Of these, 10 were QTL lead SNP, which mapped within the genes HMHA1, POLR2E, GNB5, KLHL29, ZFAT, KCNB2, CEACAM18, CCL24, and LHPP. Limited pleiotropy was observed between milking speed QTL and clinical mastitis.

CYP1A1 Relieves Lipopolysaccharide-Induced Inflammatory Responses in Bovine Mammary Epithelial Cells

The expression of cytochrome P4501A1 (CYP1A1) enzyme is changed in various organs during the host response to inflammation or infection, leading to alterations in the metabolism of endogenous and exogenous compounds. Results of this study showed that CYP1A1 expression was significantly downregulated in the mammary tissue of bovine with mastitis, in inflammatory epithelial cells (INEs) extracted from the tissue, and in lipopolysaccharide- (LPS-) induced INEs compared with their corresponding counterparts. Overexpression of CYP1A1 in bovine mammary epithelial cells alleviated the LPS-induced inhibition of epithelial proliferation, abated the LPS-induced increase of gene expression and protein secretion of inflammatory cytokine tumor necrosis factor-α and interleukin-6, and attenuated the LPS-induced activation of NF-κB signaling. These findings suggest that CYP1A1 has immense potential in the regulation of inflammatory responses in bovine mammary epithelial cells during mastitis and may serve as a useful therapeutic target in mitigating injuries caused by inflammatory overreaction.

SDF-1 in Mammary Fibroblasts of Bovine with Mastitis Induces EMT and Inflammatory Response of Epithelial Cells

Fibroblasts constitute the majority of the stromal cells within bovine mammary gland, yet the functional contributions of these cells to mastitis and fibrosis and the mechanism are poorly understood. In this study, we demonstrate that inflammation-associated fibroblasts (INFs) extracted from bovine mammary glands with clinical mastitis had different expression pattern regarding to several extracellular matrix (ECM) proteins, chemokines and cytokines compared to normal fibroblasts (NFs) from dairy cows during lactation. The INFs induced epithelial-mesenchymal transition (EMT) and inflammatory responses of mammary epithelial cells in a vitro co-culture model. These functional contributions of INFs to normal epithelial cells were mediated through their ability to secrete stromal cell-derived factor 1 (SDF-1). SDF-1 was highly secreted/expressed by INFs, lipopolysaccharide (LPS) -treated NFs, lipoteichoic acid (LTA) -treated NFs, as well as mastitic tissue compared to their counterparts. Exogenous SDF-1 promoted EMT on epithelial cells through activating NF-κB pathway, induced inflammation response and inhibited proliferation of epithelial cells. In addition, SDF-1 was able to induce mastitis and slight fibrosis of mouse mammary gland, which was attenuated by a specific inhibitor of the receptor of SDF-1. Our findings indicate that stromal fibroblasts within mammary glands with mastitis contribute to EMT and inflammatory responses of epithelial cells through the secretion of SDF-1, which could result in the inflammation spread and fibrosis within mammary gland.