Cytokines gene expression patterns of bovine milk during middle and late stages of lactation

CEBPA-Regulated Expression of SOCS1 Suppresses Milk Protein Synthesis through mTOR and JAK2-STAT5 Signaling Pathways in Buffalo Mammary Epithelial Cells

Milk protein content is a key quality indicator of milk, and therefore elucidating its synthesis mechanism has been the focus of research in recent years. Suppressor of cytokine signaling 1 (SOCS1) is an important inhibitor of cytokine signaling pathways that can inhibit milk protein synthesis in mice. However, it remains elusive whether SOCS1 plays roles in the milk protein synthesis in the buffalo mammary gland. In this study, we found that the mRNA and protein expression levels of SOCS1 in buffalo mammary tissue during the dry-off period was significantly lower than those during lactation. Overexpression and knockdown experiments of SOCS1 showed that it influenced the expression and phosphorylation of multiple key factors in the mTOR and JAK2-STAT5 signaling pathways in buffalo mammary epithelial cells (BuMECs). Consistently, intracellular milk protein content was significantly decreased in cells with SOCS1 overexpression, while it increased significantly in the cells with SOCS1 knockdown. The CCAAT/enhancer binding protein α (CEBPA) could enhance the mRNA and protein expression of SOCS1 and its promoter activity in BuMECs, but this effect was eliminated when CEBPA and NF-κB binding sites were deleted. Therefore, CEBPA was determined to promote SOCS1 transcription via the CEBPA and NF-κB binding sites located in the SOCS1 promoter. Our data indicate that buffalo SOCS1 plays a significant role in affecting milk protein synthesis through the mTOR and JAK2-STAT5 signaling pathways, and its expression is directly regulated by CEBPA. These results improve our understanding of the regulation mechanism of buffalo milk protein synthesis.

Identification of Inflammatory and Regulatory Cytokines IL-1α-, IL-4-, IL-6-, IL-12-, IL-13-, IL-17A-, TNF-α-, and IFN-γ-Producing Cells in the Milk of Dairy Cows with Subclinical and Clinical Mastitis

In naturally occurring bovine mastitis, effects of infection depend on the host inflammatory response, including the effects of secreted cytokines. Knowledge about the inflammatory and regulatory cytokines in milk cells of free-stall barn dairy cows and in naturally occurring mastitis is lacking as most studies focus on induced mastitis. Hereby, the aim of the study was to determine inflammatory and regulatory cytokines in the milk of dairy cows with subclinical and clinical mastitis. The following examinations of milk samples were performed: differential counting of somatic cells (SCC), bacteriological examination, and immunocytochemical analysis. Mean SCC increased in subclinical and clinical mastitis cases. The number of pathogenic mastitis-causing bacteria on plates increased in subclinical mastitis cases but decreased in clinical mastitis. The inflammatory and regulatory markers in the milk cells of healthy cows showed the highest mean cell numbers (%). In mastitis cases, immunoreactivity was more pronounced for IL-4, IL-6, IL-12, IL-13, IL-17A, TNF-α, and IFN-γ. Data about subclinical and clinical mastitis demonstrate inflammatory responses to intramammary infection driven by IL-1α, IL-4, and IL-17A. Moreover, the host defense response in mastitis is characterized by continuation or resolution of initial inflammation. IL-12 and INF-γ immunoreactivity was recognized to differ mastitis cases from the relative health status.

Relationship Between mRNA of Immune Factors Expressed by Milk Somatic Cells and Bacteria Present in Healthy Lactating Holstein Cows

Introduction

The characteristics of immune factors in somatic cells from lactating dairy cows and their association with commensal bacteria in normal milk have not been clarified. This study investigated the relationship between the pathogenic bacteria in milk and somatic cell immune factors in healthy lactating cows.

Material and Methods

In total 44 healthy Holstein cows were studied on one farm. Milk samples were collected aseptically using a cannula and these samples were cultured for detection of bacteria and analysis of mRNA of immune factors expressed by somatic cells. Cows were divided into two groups based on the microbial status of their milk samples: 12 cows showed bacteria in cultures (positive group), and the other 32 cows did not (negative group).

Results

The mRNA levels of IL-6, lactotransferrin, and cathelicidin expressed by somatic cells after milking decreased significantly compared to those before milking in both groups (P < 0.05). There were significantly lower mRNA levels of IL-6 and cathelicidin in the positive group compared to those in the negative group before milking.

Conclusion

These results suggest that mRNA levels of IL-6 and cathelicidin expressed by the somatic cells may be affected by the presence of bacteria in healthy lactating dairy cows.

Immunomodulation of IL-1, IL-6 and IL-8 cytokines by Prosopis juliflora alkaloids during bovine sub-clinical mastitis

The current work is focused on establishing therapeutic protocol using unconventional drugs of herbal origin and studying their mechanism of action at molecular level in the treatment of bovine sub-clinical mastitis. It explores the potential of different cytokines which can be used for diagnosis, prognosis and monitoring of bovine sub-clinical mastitis. Prosopis juliflora alkaloids was administered intramammarily in 24 sub-clinically affected quarters once a day for 5 consecutive days at the rate of 10 ml of 1% formulation. In 18 disease control quarters, sterile normal saline was infused. The bacterial cultural examination, somatic cell count (SCC) and cytokines (IL-1β, IL-6, IL-8, IL-12, GM-CSF, IFN-γ, TNF-α) expression by real-time PCR were evaluated on day 7, 14, 21 and 28 post-last treatment from milk samples. Around 75.0% of treatment group quarters showed significant (p < 0.05) reduction in SCC on day 28 post-last treatment, whereas 94.4% control group quarters did not show any significant decline in SCC. 58.3% of treated quarters showed both bacteriological cure as well as significant (p < 0.05) reduction in SCC on day 28 post-last treatment. While, among control group quarters, 83.3% quarters not only remained bacteriological positive, they also did not show any significant decline in SCC. The in vitro antimicrobial activity of alkaloids of P. juliflora was evaluated. Lower concentrations of alkaloids (0.25% and 0.50%) dissolved in normal saline showed zone of inhibition against 12 out of 15 isolates, however higher concentration (1, 1.5, 2, 2.5 and 5%) showed zone of inhibition against all 15 bacterial isolates. The gene expression level of IL-1β, IL-8 and IFN-γ cytokines exhibited significant difference between healthy and sub-clinically affected quarters highlighting the potential of these cytokines in the diagnosis of bovine sub-clinical mastitis. Down-regulation of IL-1, IL-6, IL-8 and IFN-γ cytokines in treated quarters can be explored for making the prognosis and monitoring post-treatment disease progression of bovine sub-clinical mastitis. The P. juliflora alkaloid demonstrated strong in vitro and in vivo antibacterial activity, along with causing immunomodulation by enhancing post-treatment gene expression of IL-1, IL-6 and IL-8 cytokines. Therefore, P. juliflora alkaloids hold a strong claim as an effective alternative herbal therapy in bovine sub-clinical mastitis.

Targeted Analysis Reveals an Important Role of JAK-STAT-SOCS Genes for Milk Production Traits in Australian Dairy Cattle

The Janus kinase and signal transducer and activator of transcription (JAK-STAT) pathway genes along with suppressors of cytokine signalling (SOCS) family genes play a crucial role in controlling cytokine signals in the mammary gland and thus mammary gland development. Mammary gene expression studies showed differential expression patterns for all the JAK-STAT pathway genes. Gene expression studies using qRT-PCR revealed differential expression of SOCS2, SOCS4, and SOCS5 genes across the lactation cycle in dairy cows. Using genotypes from 1,546 Australian Holstein-Friesian bulls, a statistical model for an association analysis based on SNPs within 500 kb of JAK-STAT pathway genes, and SOCS genes alone was constructed. The analysis suggested that these genes and pathways make a significant contribution to the Australian milk production traits. There were 24 SNPs close to SOCS1, SOCS3, SOCS5, SOCS7, and CISH genes that were significantly associated with Australian Profit Ranking (APR), Australian Selection Index (ASI), and protein yield (PY). This study supports the view that there may be some merit in choosing SNPs around functionally relevant genes for the selection and genetic improvement schemes for dairy production traits.

The Mammary Gland in Mucosal and Regional Immunity

The mammary gland (MG) lacks a mucosa but is part of the mucosal immune system because of its role in passive mucosal immunity. The MG is not an inductive site for mucosal immunity. Rather, synthesis of immunoglobulin (Ig)A by plasma cells stimulated at distal inductive sites dominate in the milk of rodents, humans, and swine whereas IgG1 derived from serum predominates in ruminants. Despite the considerable biodiversity in the role of the MG, IgG passively transfers the maternal systemic immunological experience whereas IgA transfers the mucosal immunological experience. Although passive antibodies are protective, they and other lacteal constituents can be immunoregulatory. Immune protection of the MG largely depends on the innate immune system; the monocytes–macrophages group together with intraepithelial lymphocytes is dominant in the healthy gland. An increase in somatic cells (neutrophils) and various interleukins signal infection (mastitis) and a local immune response in the MG. The major role of the MG to mucosal immunity is the passive immunity supplied to the suckling neonate.

The Immunology of Mammary Gland of Dairy Ruminants between Healthy and Inflammatory Conditions

The health of dairy animals, particularly the milk-producing mammary glands, is essential to the dairy industry because of the crucial hygienic and economic aspects of ensuring production of high quality milk. Due to its high prevalence, mastitis is considered the most important threat to dairy industry, due to its impacts on animal health and milk production and thus on economic benefits. The MG is protected by several defence mechanisms that prevent microbial penetration and surveillance. However, several factors can attenuate the host immune response (IR), and the possession of various virulence and resistance factors by different mastitis-causing microorganisms greatly limits immune defences and promotes establishment of intramammary infections (IMIs). A comprehensive understanding of MG immunity in both healthy and inflammatory conditions will be an important key to understand the nature of IMIs caused by specific pathogens and greatly contributes to the development of effective control methods and appropriate detection techniques. Consequently, this review aims to provide a detailed overview of antimicrobial defences in the MG under healthy and inflammatory conditions. In this sense, we will focus on pathogen-dependent variations in IRs mounted by the host during IMI and discuss the potential ramifications of these variations.

Staphylococcus aureus virulence factors in evasion from innate immune defenses in human and animal diseases

In the last decades, Staphylococcus aureus acquired a dramatic relevance in human and veterinary medicine for different reasons, one of them represented by the increasing prevalence of antibiotic resistant strains. However, antibiotic resistance is not the only weapon in the arsenal of S. aureus. Indeed, these bacteria have plenty of virulence factors, including a vast ability to evade host immune defenses. The innate immune system represents the first line of defense against invading pathogens. This system consists of three major effector mechanisms: antimicrobial peptides and enzymes, the complement system and phagocytes. In this review, we focused on S. aureus virulence factors involved in the immune evasion in the first phases of infection: TLR recognition avoidance, adhesins affecting immune response and resistance to host defenses peptides and polypeptides. Studies of innate immune defenses and their role against S. aureus are important in human and veterinary medicine given the problems related to S. aureus antimicrobial resistance. Moreover, due to the pathogen ability to manipulate the immune response, these data are needed to develop efficacious vaccines or molecules against S. aureus.

Differential levels of mRNA transcripts encoding immunologic mediators in mammary gland secretions from dairy cows with subclinical environmental Streptococci infections

Dry-off, and the period around parturition, are associated with increased susceptibility to intramammary infections in dairy cows. The immunological profiles of mammary gland secretions during these periods are not well described. The objective of the present study was to better characterize association(s) between chronic subclinical Environmental Streptococci infections at dry-off and relative levels of mRNA transcripts encoding multiple immunologic mediators present in cells derived from mammary gland secretions at dry-off and continuing through parturition. The chronic subclinical bacterial infections in the present study were characterized by multiple isolations of Streptococcus species and elevated SSC for a minimum of three weeks prior to dry-off. The majority of differences between principal and control quarters were identified at dry-off. Transcript levels of IL-17, IL2Rα and iNOS were increased while pro-inflammatory cytokine IL-6, and the regulatory cytokine IL-10, were reduced. Following antibiotic treatment of mammary glands, IL-17 transcripts remained elevated over the course of the study, indicative of a persistent insult. IL-4 transcript levels were modestly elevated at 7 days following dry-off and significantly elevated at 14 days, consistent with activated T(H)1 and T(H)2 lymphocytes in the principal quarters, respectively. From a temporal perspective, transcript levels of IL-8 decreased in all animals through the dry-off period animals and returned to pre-dry-off levels at parturition; levels of iNOS peaked at parturition. Five of the six principal cows experienced recurrent bacterial mastitis during the subsequent lactation; four were in the same quarter as was initially infected with Streptococcus and three of these four were due to coliforms. Taken together, this apparent chronic susceptibility of select mammary glands to bacterial infection would suggest a physiologic and/or immunologic dysfunction. Identification of factor(s) that contribute to the predisposition of mammary glands to developing mastitis should facilitate development of new control strategies.

Innate immune response of bovine mammary gland to pathogenic bacteria responsible for mastitis

Mastitis (mammary gland inflammation) is one of the most important bovine diseases causing economic losses to dairy producers. Mammary gland inflammation is a consequence of the activity of a number of cell and soluble factors that function together to eliminate invading microorganisms. The factors involved in this inflammatory response differ depending on the infectious agent. This review analyzes the factors involved in the immunologic mechanisms against the main pathogenic bacteria causing mastitis, and emphasizes the innate immune response of the mammary gland. Knowledge, at the molecular level, of the mammary gland immune response during infection by pathogenic bacteria is fundamental to the design of effective therapies to control and eradicate bovine mastitis.

The cytokines of bovine mammary gland: prospects for diagnosis and therapy

The lack of efficacy of conventional strategies for the maintenance of healthy udders in domestic cattle has prompted studies on the use of cytokines for this purpose. The adjuvant use of recombinant bovine cytokines, such as IL-2, IFN-gamma and TNF-alpha, in normal mammary gland, mobilizes innate and acquired immunity. However, stimulated immunity does not prevent or eradicate infection, particularly in the case of Staphylococcus aureus mastitis. Cytokines do, however, improve the bactericidal efficiency of certain antibiotics. The subtle and sensitive changes in the cytokine network of normal and mastitic bovine mammary gland may encourage the use of cytokines in the diagnosis and prognosis of udder health. Numerous studies support this hypothesis, and detection and monitoring of cytokines could become an important alternative management for udder health. The use of cytokines in the immunotherapy, diagnosis and prognosis of mastitis will grow with knowledge of the cytokine network in bovine mammary glands and the development of efficient cytokine diagnostic techniques.

Quantitative analysis of pro-inflammatory cytokine mRNA expression in Theileria annulata-infected cell lines derived from resistant and susceptible cattle

The pathogenic mechanisms involved in tropical theileriosis, caused by the tick-borne protozoan parasite Theileria annulata, are unclear. Pathology is associated with the schizont stage of the parasite, which resides within bovine macrophages. Breed-specific differences in pathology have been observed in cattle, several Bos indicus breeds are relatively resistant to tropical theileriosis whilst Bos taurus cattle are highly susceptible. Infected cells express pro-inflammatory cytokines and it has been hypothesized that these cytokines play a major role in the pathology of the disease. Therefore, using quantitative RT-PCR we investigated the expression of the key candidates, interleukin 1 beta (IL-1beta), IL-6 and tumour necrosis factor alpha (TNF-alpha), in T. annulata low passage infected cell lines derived ex vivo from experimental infection of resistant and susceptible cattle. mRNA for each cytokine was detected in all cell lines investigated at levels higher than those observed in resting monocytes. However, the analyses did not identify any breed-specific differences. Therefore, these results are not consistent with the hypothesis that differential regulation of infected cell derived pro-inflammatory cytokines (IL-1beta, IL-6 and TNF-alpha) accounts for the breed-related differences in resistance and susceptibility to T. annulata infection. Other, currently unknown mechanisms may be of greater importance.

The cytokine markers in Staphylococcus aureus mastitis of bovine mammary gland

TaqMan real time PCR was used to study the transcriptional activity of the bovine IL-2, IL-6, IL-12p40, IFN-gamma, TNF-alpha and granulocyte-monocyte colony stimulating factor of whole milk cells in bovine mammary gland experimentally infected with Staphylococcus aureus. Cytokine transcriptional activity was monitored at 7, 24 and 32 h Post-infection (Pi). IL-12 and TNF-alpha levels were significantly elevated at 24 h Pi followed by sharp decrease at 32 h pi. IL-2 level was decreased at 32 h pi. IL-12 and IFN-gamma showed a significant interaction at 24 h pi. The significant elevations of the IL-12 and TNF-alpha transcriptional level most likely indicate their important role in regulation of the immune responses of bovine mammary gland in S. aureus infection. Depression of IL-2 could reflect the suppressive nature of the S. aureus mastitis.