Early inflammatory events of mastitis-a pilot study with the isolated perfused bovine udder

Transcriptome sequencing analysis of bovine mammary epithelial cells induced by lipopolysaccharide

Mastitis in cows is caused by the inflammation of the mammary glands due to an infection by external pathogenic bacteria. Mammary gland epithelial cells, which are in direct contact with the external environment, are responsible for the first line of defense of the mammary gland against pathogenic bacteria, playing an essential role in immune defense. To investigate the mechanism of bovine mammary epithelial cells in the inflammatory process, we treated the cells with LPS for 12 hours and analyzed the changes in mRNA by transcriptome sequencing. The results showed that compared to the control group, the LPS treatment group had 121 up-regulated genes and 18 down-regulated genes. GO and KEGG enrichment analysis revealed that these differential genes were mainly enriched in the IL-17 signaling pathway, Legionellosis, Cytokine-cytokine receptor interaction, NF-kappa B signaling pathway, and other signaling pathways. Furthermore, the expression of GRO1 and CXCL3 mRNAs increased significantly after LPS treatment. These findings provide new insights for the treatment of mastitis in cows in the future.

Application of lipopolysaccharide in establishing inflammatory models

Lipopolysaccharide (LPS), a unique component of the outer membrane of Gram-negative bacteria, possesses immune-activating properties. It induces an immune response by stimulating host cells to produce a lot of inflammatory cytokines with a thermogenic effect, which may cause an inflammatory response. In the past few decades, the structure and function of LPS and its mechanism leading to inflammation have been extensively analyzed. Since LPS can cause inflammation, it is often used to establish inflammation models. These models are crucial in the study of inflammatory diseases that pose a serious threat to human health. In addition, the non-pro-inflammatory effects of LPS under certain circumstances are also being studied widely. This review summarizes the methods by which LPS has been used to establish inflammatory models at the cellular and animal levels to study related diseases. It also introduces in detail the evaluation indicators necessary for the successful establishment of these models, providing a reference for future research.

Immune defenses of the mammary gland epithelium of dairy ruminants

The epithelium of the mammary gland (MG) fulfills three major functions: nutrition of progeny, transfer of immunity from mother to newborn, and its own defense against infection. The defense function of the epithelium requires the cooperation of mammary epithelial cells (MECs) with intraepithelial leucocytes, macrophages, DCs, and resident lymphocytes. The MG is characterized by the secretion of a large amount of a nutrient liquid in which certain bacteria can proliferate and reach a considerable bacterial load, which has conditioned how the udder reacts against bacterial invasions. This review presents how the mammary epithelium perceives bacteria, and how it responds to the main bacterial genera associated with mastitis. MECs are able to detect the presence of actively multiplying bacteria in the lumen of the gland: they express pattern recognition receptors (PRRs) that recognize microbe-associated molecular patterns (MAMPs) released by the growing bacteria. Interactions with intraepithelial leucocytes fine-tune MECs responses. Following the onset of inflammation, new interactions are established with lymphocytes and neutrophils recruited from the blood. The mammary epithelium also identifies and responds to antigens, which supposes an antigen-presenting capacity. Its responses can be manipulated with drugs, plant extracts, probiotics, and immune modifiers, in order to increase its defense capacities or reduce the damage related to inflammation. Numerous studies have established that the mammary epithelium is a genuine effector of both innate and adaptive immunity. However, knowledge gaps remain and newly available tools offer the prospect of exciting research to unravel and exploit the multiple capacities of this particular epithelium.

Lipopolysaccharide-Induced Model of Neuroinflammation: Mechanisms of Action, Research Application and Future Directions for Its Use

Despite advances in antimicrobial and anti-inflammatory therapies, inflammation and its consequences still remain a significant problem in medicine. Acute inflammatory responses are responsible for directly life-threating conditions such as septic shock; on the other hand, chronic inflammation can cause degeneration of body tissues leading to severe impairment of their function. Neuroinflammation is defined as an inflammatory response in the central nervous system involving microglia, astrocytes, and cytokines including chemokines. It is considered an important cause of neurodegerative diseases, such as Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis. Lipopolysaccharide (LPS) is a strong immunogenic particle present in the outer membrane of Gram-negative bacteria. It is a major triggering factor for the inflammatory cascade in response to a Gram-negative bacteria infection. The use of LPS as a strong pro-inflammatory agent is a well-known model of inflammation applied in both in vivo and in vitro studies. This review offers a summary of the pathogenesis associated with LPS exposure, especially in the field of neuroinflammation. Moreover, we analyzed different in vivo LPS models utilized in the area of neuroscience. This paper presents recent knowledge and is focused on new insights in the LPS experimental model.

Investigation of the pathophysiology of bacterial mastitis using precision-cut bovine udder slices

Mastitis in cattle is a major health problem as well as incurring high costs for the dairy industry. To assess the suitability of precision-cut bovine udder slices (PCBUS) for bovine mastitis studies, we infected PCBUS with 2 different Staphylococcus aureus strains. Accordingly, we investigated both the tissue response to infection based on immune mediators at the mRNA and protein levels and the invasion of bacteria within the tissue. The studied proteins represent immune mediators of early inflammation [IL-1β, tumor necrosis factor-α (TNF-α), prostaglandin E₂ (PGE₂)] and showed a time-dependent increase in concentration. Infection of PCBUS with S. aureus resulted in increased expression of proinflammatory cytokines and chemokines such as TNF-α, C-C motif chemokine ligand 20 (CCL20), IL-1β, IL-6, and IL-10, but not C-X-C motif chemokine ligand 8 (CXCL8), lingual antimicrobial peptide (LAP), or S100 calcium binding protein A9 (S100A9) at the mRNA level. To compare the data acquired with this model, we carried out investigations on primary bovine mammary epithelial cells. Our results showed that the immune responses of both models-PCBUS and primary bovine mammary epithelial cells-were similar. In addition, investigations using PCBUS enabled us to demonstrate adherence of bacteria in the physiological cell network. These findings support the use of PCBUS in studies designed to further understand the complex pathophysiological processes of infection and inflammation in bovine mastitis and to investigate alternative therapies for mastitis.

Testing Two Somatic Cell Count Cutoff Values for Bovine Subclinical Mastitis Detection Based on Milk Microbiota and Peripheral Blood Leukocyte Transcriptome Profile

Somatic cell count (SCC) is an important indicator of the health state of bovine udders. However, the exact cut-off value used for differentiating the cows with healthy quarters from the cows with subclinical mastitis remains controversial. Here, we collected composite milk (milk from four udder quarters) and peripheral blood samples from individual cows in two different dairy farms and used 16S rRNA gene sequencing combined with RNA-seq to explore the differences in the milk microbial composition and transcriptome of cows with three different SCC levels (LSCC: <100,000 cells/mL, MSCC: 100,000−200,000 cells/mL, HSCC: >200,000 cells/mL). Results showed that the milk microbial profiles and gene expression profiles of samples derived from cows in the MSCC group were indeed relatively easily discriminated from those from cows in the LSCC group. Discriminative analysis also uncovered some differentially abundant microbiota at the genus level, such as Bifidobacterium and Lachnospiraceae_AC2044_group, which were more abundant in milk samples from cows with SCC below 100,000 cells/mL. As for the transcriptome profiling, 79 differentially expressed genes (DEGs) were found to have the same direction of regulation in two sites, and functional analyses also showed that biological processes involved in inflammatory responses were more active in MSCC and HSCC cows. Overall, these results showed a similarity between the milk microbiota and gene expression profiles of MSCC and HSCC cows, which presented further evidence that 100,000 cells/ml is a more optimal cut-off value than 200,000 cells/mL for intramammary infection detection at the cow level.