TGF-β1 promotes Staphylococcus aureus adhesion to and invasion into bovine mammary fibroblasts via the ERK pathway

UID-Dual Transcriptome Sequencing Analysis of the Molecular Interactions between Streptococcus agalactiae ATCC 27956 and Mammary Epithelial Cells

Streptococcus agalactiae ATCC 27956 is a highly contagious Gram-positive bacterium that causes mastitis, has a high infectivity for mammary epithelial cells, and becomes challenging to treat. However, the molecular interactions between it and mammary epithelial cells remain poorly understood. This study analyzed differential gene expression in mammary epithelial cells with varying levels of S. agalactiae infection using UID-Dual transcriptome sequencing and bioinformatics tools. This study identified 211 differentially expressed mRNAs (DEmRNAs) and 452 differentially expressed lncRNAs (DElncRNAs) in host cells, primarily enriched in anti-inflammatory responses, immune responses, and cancer-related processes. Additionally, 854 pathogen differentially expressed mRNAs (pDEmRNAs) were identified, mainly enriched in protein metabolism, gene expression, and biosynthesis processes. Mammary epithelial cells activate pathways, such as the ERK1/2 pathway, to produce reactive oxygen species (ROS) to eliminate bacteria. The bacteria disrupt the host's innate immune mechanisms by interfering with the alternative splicing processes of mammary epithelial cells. Specifically, the bacterial genes of tsf, prfB, and infC can interfere with lncRNAs targeting RUNX1 and BCL2L11 in mammary epithelial cells, affecting the alternative splicing of target genes and altering normal molecular regulation.

Effect of allogeneic pure platelet-rich plasma, sodium cloxacillin, and their combination for the treatment of subclinical mastitis in crossbred cows

Introduction

Bovine subclinical mastitis (SCM) caused by Gram-positive bacteria is a major cause of economic loss in the dairy industry, exacerbated in situations where antimicrobial resistance is present. Pure platelet-rich plasma (P-PRP) may be a therapeutic alternative for SCM, when used alone or with antibiotics, such as sodium cloxacillin (SC). This study aimed 1) to evaluate the therapeutic efficacy of allogeneic P-PRP, SC, and their combination (P-PRP+SC) in cows with SCM caused by Staphylococcus aureus and by streptococci (Staphylococcus aureus and S. dysgalactiae); 2) to determine the concentrations of somatic cells (SCC), interleukin 1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and TGF-β1 in milk samples of the cows.

Methods

130 cows from 4 dairy herds completed the study, of which 40 cows were treated with P-PRP (10 mL), 28 cows with SC (5g), 36 with P-PRP+SC (10mL/5g), and 26 did not receive no treatment (negative control group, NCG).

Results

The overall bacteriological cure was observed in 10/40 (25%) cows in the P-PRP group, 9/28 (32.14%) animals in the SC group, 26/36 (72.22%) cows in the P-PRP+SC group, and 10/26 (38.46%) animals in the NCG. SCM caused by S. aureus (82/130, 63.08%), was cured in 6/24 (25%) cows treated with P-PRP, 7/24 (29.2%) cows treated with SC, 8/16 (50%) animals treated with P-PRP+SC, and in 8/18 (44.4%) cows in NCG. For SCM caused by the streptococci (48/130, 36.91%), the cure was achieved in 4/12 (33.3%) cows treated with P-PRP, 2/4 (50%) cows treated with SC, 18/20 (90%) cows treated with P-PRP+SC, and in 2/8 (25%) cows of the NCG. SCC was significantly (p < 0.001) affected by the treatment, herd, cure, bacteria group, and number of calvings factors. IL-1β milk concentrations were significantly (p < 0.001) influenced by treatment and farm factors, and the interaction between these factors. TNF-α milk concentrations were significantly (p < 0.001) influenced by time factor. TGF-β1 milk concentrations were significantly affected by the time and cure factors.

Conclusion

The combination of P-PRP and SC showed the best therapeutic response (90%) against bovine SCM caused by streptococci. However, none of the treatments showed an effective therapeutic response against S. aureus.

The role of transforming growth factor beta-1 protein in Escherichia coli secondary infection induced by H9N2 avian influenza virus in chickens

The H9N2 subtype of avian influenza virus (AIV) is common in poultry production. It causes mild clinical signs but rarely leads to poultry mortalities. However, higher mortality can occur in chickens with co-infections, especially avian pathogenic Escherichia coli (APEC), which results in huge economic losses for the poultry industry. Unfortunately, the mechanism of co-infection remains unknown. Our previous studies screened several proteins associated with bacterial adhesion, including transforming growth factor beta-1 (TGF-β1), integrins, cortactin, E-cadherin, vinculin, and fibromodulin. Herein, we investigated the contribution of TGF-β1 to APEC adhesion after H9N2 infection. We first infected H9N2 and APEC in chicken, chicken embryo and DF-1 cells, and demonstrated that H9N2 infection promotes APEC adhesion to hosts in vitro and in vivo by plate count method. Through real-time fluorescence quantification and enzyme-linked immunosorbent assay, it was demonstrated that H9N2 infection not only increases TGF-β1 expression but also its activity in a time-dependent manner. Then, through exogenous addition of TGF-β1 and overexpression, we further demonstrated that TGF-β1 can increase the adhesion of endothelial cells to DF-1 cells. Furthermore, the capacity of APEC adhesion to DF-1 cells was significantly decreased either by adding a TGF-β1 receptor inhibitor or using small interfering RNAs to interfere with the expression of TGF-β1. To sum up, H9N2 infection can promote the upregulation of TGF-β1 and then increase the adhesion ability of APEC. Targeting TGF-β1 and its associated pathway will provide valuable insights into the clinical treatment of E. coli secondary infection induced by H9N2 infection.

Host-Targeted Therapeutics against Multidrug Resistant Intracellular Staphylococcus aureus

Staphylococcus aureus is a facultative intracellular pathogen that invades and replicates within many types of human cells. S. aureus has shown to rapidly overcome traditional antibiotherapy by developing multidrug resistance. Furthermore, intracellular S. aureus is protected from the last-resort antibiotics—vancomycin, daptomycin, and linezolid—as they are unable to achieve plasma concentrations sufficient for intracellular killing. Therefore, there is an urgent need to develop novel anti-infective therapies against S. aureus infections. Here, we review the current state of the field and highlight the exploitation of host-directed approaches as a promising strategy going forward.

HIF-1α promotes the keloid development through the activation of TGF-β/Smad and TLR4/MyD88/NF-κB pathways

A keloid is defined as an overgrowth of the dense fibrous tissues that form around a wound. Since they destroy the vascular network, keloid tissues often exhibit anoxic conditions. Hypoxia-inducible factor-1α (HIF-1α) is a core factor that mediates hypoxia stress responses and regulates the hypoxic cellular and biological behaviors. In this study, we found that the expression level of HIF-1α in keloid tissue was significantly higher than that in the normal skin tissue. Hypoxia-induced HIF-1α expression significantly inhibited cellular apoptosis and promoted cellular proliferation in keloid fibroblasts but not in normal fibroblasts. Specifically, HIF-1α activated the TGF-β/Smad and TLR4/MyD88/NF-κB pathways, and the interaction of these two pathways may promote the development of keloids. Moreover, in vivo experiments showed that the inhibition of HIF-1α significantly reduced the growth of keloids.

TGF-β1 promoted the infection of bovine mammary epithelial cells by Staphylococcus aureus through increasing expression of cells' fibronectin and integrin β1

Mastitis is a disease that affects dairy cattle and causes a decline in milk quality as well as economic loss worldwide. TGF-β1 levels are usually increased during mastitis; however, it is unknown whether TGF-β1 is involved in bovine mastitis. Therefore, this study evaluated the effects of TGF-β1 on the susceptibility of bovine mammary epithelial cells (BMECs) to Staphylococcus aureus (S. aureus). The results revealed that S. aureus adhesion to and invasion of BMECs was significantly increased after cells were treated with TGF-β1. Adhesion of S. aureus to BMECs was increased dramatically by upregulation of fibronectin (Fn) and integrin β1 (ITGB1), while the increase in the susceptibility of BMECs to S. aureus was blocked by specific antibodies against either Fn or ITGB1. These results indicated that adhesion and invasion were increased by TGF-β1-induced upregulation of both Fn and ITGB1. Furthermore, TGF-β1 treatment prior to S. aureus infection significantly increased S. aureus colonization as well as Fn and ITGB1 expression in the mammary glands of mice. These results suggest that TGF-β1 promoted the expression of Fn and ITGB1 on the surface of BMECs and contributed to mammary gland infection in vitro and in vivo. The results of this study imply that Fn and ITGB1 may be useful therapeutic targets for the treatment of mastitis in dairy cows.

Exosomes Derived from Bovine Mammary Epithelial Cells Treated with Transforming Growth Factor-β1 Inhibit the Proliferation of Bovine Macrophages

Transforming growth factor (TGF)-β1 is a multifunctional cytokine that plays an important role in regulating immune cell proliferation. We speculate that high expression of TGF-β1 may affect the immunity of dairy cows. In this study, untreated exosomes (un-exo) derived from an untreated bovine mammary epithelial cell line (MAC-T) and TGF-β1-treated exosomes (t-exo) derived from TGF-β1-treated MAC-T cells were isolated by ultracentrifugation and identified by electron microscopy and Western blotting. Then, un-exo and t-exo were used to treat a bovine macrophage cell line (BOSMAC), and the proliferative ability of BOSMAC cells was detected by an 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay and flow cytometry. The expression and phosphorylation levels of p38 were analyzed by q-PCR and Western blotting. The results showed that both exosome types exhibited the basic characteristics of exosomes. In BOSMAC cells treated with t-exo, significant inhibition of cell proliferation was observed, and the cell cycle progression was inhibited, while no difference was found between the un-exo and control groups. Only treatment with t-exo increased the expression and phosphorylation of p38, and the addition of the p38 inhibitor SB203580 abrogated the inhibition of BOSMAC cell proliferation by t-exo. Our results demonstrated that t-exo inhibited the proliferation of bovine macrophages by stimulating p38 MAPK and might interfere with immunity in dairy cattle. This finding may provide a new strategy for improving immunity and preventing breast-related diseases in dairy cows.

Host-directed kinase inhibitors act as novel therapies against intracellular Staphylococcus aureus

Host-directed therapeutics are a promising anti-infective strategy against intracellular bacterial pathogens. Repurposing host-targeted drugs approved by the FDA in the US, the MHRA in the UK and/or regulatory equivalents in other countries, is particularly interesting because these drugs are commercially available, safe doses are documented and they have been already approved for other clinical purposes. In this study, we aimed to identify novel therapies against intracellular Staphylococcus aureus, an opportunistic pathogen that is able to exploit host molecular and metabolic pathways to support its own intracellular survival. We screened 133 host-targeting drugs and found three host-directed tyrosine kinase inhibitors (Ibrutinib, Dasatinib and Crizotinib) that substantially impaired intracellular bacterial survival. We found that Ibrutinib significantly increased host cell viability after S. aureus infection via inhibition of cell invasion and intracellular bacterial proliferation. Using phosphoproteomics data, we propose a putative mechanism of action of Ibrutinib involving several host factors, including EPHA2, C-JUN and NWASP. We confirmed the importance of EPHA2 for staphylococcal infection in an EPHA2-knock-out cell line. Our study serves as an important example of feasibility for identifying host-directed therapeutics as candidates for repurposing.

TGF-beta signalling in bovine mammary gland involution and a comparative assessment of MAC-T and BME-UV1 cells as in vitro models for its study

The goal of the dairy industry is ultimately to increase lactation persistency, which is the length of time during which peak milk yield is sustained. Lactation persistency is determined by the balance of cell apoptosis and cell proliferation; when the balance is skewed toward the latter, this results in greater persistency. Thus, we can potentially increase milk production in dairy cows through manipulating apoptogenic and antiproliferative cellular signaling that occurs in the bovine mammary gland. Transforming growth factor beta 1 (TGFβ1) is an antiproliferative and apoptogenic cytokine that is upregulated during bovine mammary gland involution. Here, we discuss possible applications of TGFβ1 signaling for the purposes of increasing lactation persistency. We also compare the features of mammary alveolar cells expressing SV-40 large T antigen (MAC-T) and bovine mammary epithelial cells-clone UV1 (BME-UV1) cells, two extensively used bovine mammary epithelial cell lines, to assess their appropriateness for the study of TGFβ1 signaling. TGFβ1 induces apoptosis and arrests cell growth in BME-UV1 cells, and this was reported to involve suppression of the somatotropic axis. Conversely, there is no proof that exogenous TGFβ1 induces apoptosis of MAC-T cells. In addition to TGFβ1's different effects on apoptosis in these cell lines, hormones and growth factors have distinct effects on TGFβ1 secretion and synthesis in MAC-T and BME-UV1 cells as well. MAC-T and BME-UV1 cells may behave differently in response to TGFβ1 due to their contrasting phenotypes; MAC-T cells have a profile indicative of both myoepithelial and luminal populations, while the BME-UV1 cells exclusively contain a luminal-like profile. Depending on the nature of the research question, the use of these cell lines as models to study TGFβ1 signaling should be carefully tailored to the questions asked.

N-carbamylglutamate restores nitric oxide synthesis and attenuates high altitude-induced pulmonary hypertension in Holstein heifers ascended to high altitude

Background

High-altitude pulmonary hypertension (HAPH) is a life-threating condition for animals in high altitude, and disturbance of endothelial nitric oxide (NO) synthesis contributes to its pathogenesis. N-carbamylglutamate (NCG), which enhances arginine synthesis, promotes endogenous synthesis of NO. In this study, we determined the effects of NCG on alleviating HAPH in Holstein heifers that ascended to Tibet (Lhasa, 3,658 m).

Methods

Exp. 1, 2,000 Holstein heifers were transported from low elevation (1,027 m) to Lhasa. After being exposed to hypoxia for 1 yr, Holstein heifers were assigned to a healthy group (Control, n = 6) with mean pulmonary hypertension (mPAP) < 41 mmHg, and an HAPH affected group (HAPH, n = 6) with mPAP > 49 mmHg. Lung tissues were collected to evaluate histopathological changes and the expression of endothelial nitric oxide synthase (eNOS). Exp. 2, ten healthy heifers and 10 HAPH affected heifers were supplemented with NCG (20 g/d per heifer) for 4 wk. Physiological parameters were determined and blood samples were collected on d − 1 and d 28 of the feeding trial.

Results

Expression of eNOS in small pulmonary arteriole intima was higher in the healthy than HAPH group (P = 0.006), whereas HAPH group had significantly thicker media and adventitia than healthy group (all P < 0.05). The mRNA of eNOS and protein level of eNOS were higher in the lungs of heifers in the healthy group than in the HAPH group (both P < 0.001), whereas endothelin-1 protein levels were higher in HAPH group than in the healthy group (P = 0.025). NCG supplementation decreased mPAP and ammonia (both P = 0.001), whereas it increased the expression of eNOS, arginine, and plasma NO (all P < 0.05).

Conclusions

The expression of eNOS was decreased in Holstein heifers with HAPH. NCG supplementation decreased mPAP through the restoration of eNOS and endogenous NO synthesis.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0277-6) contains supplementary material, which is available to authorized users.

The Mammary Microenvironment in Mastitis in Humans, Dairy Ruminants, Rabbits and Rodents: A One Health Focus

The One Health concept promotes integrated evaluation of human, animal, and environmental health questions to expedite advances benefiting all species. A recognition of the multi-species impact of mastitis as a painful condition with welfare implications leads us to suggest that mastitis is an ideal target for a One Health approach. In this review, we will evaluate the role of the mammary microenvironment in mastitis in humans, ruminants and rabbits, where appropriate also drawing on studies utilising laboratory animal models. We will examine subclinical mastitis, clinical lactational mastitis, and involution-associated, or dry period, mastitis, highlighting important anatomical and immunological species differences. We will synthesise knowledge gained across different species, comparing and contrasting disease presentation. Subclinical mastitis (SCM) is characterised by elevated Na/K ratio, and increased milk IL-8 concentrations. SCM affecting the breastfeeding mother may result in modulation of infant mucosal immune system development, whilst in ruminants notable milk production losses may ensue. In the case of clinical lactational mastitis, we will focus on mastitis caused by Staphylococcus aureus and Escherichia coli. Understanding of the pathogenesis of involution-associated mastitis requires characterization of the structural and molecular changes occurring during involution and we will review these changes across species. We speculate that milk accumulation may act as a nidus for infection, and that the involution 'wound healing phenotype' may render the tissue susceptible to bacterial infection. We will discuss the impact of concurrent pregnancy and a 'parallel pregnancy and involution signature' during bovine mammary involution.