1- University of Zabol
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Extended abstract
Introduction and Objective: Bovine mastitis is one of the most important diseases in dairy herds worldwide, affecting cows during dry and lactation periods and causing significant economic losses. This disease is considered the most cost disease in dairy cows globally. Given the economic importance of this issue, numerous research efforts have focused on developing practical and effective methods for preventing mastitis. Additionally, bovine mastitis caused by infectious agents, such as bacteria, can be transmitted to humans through milk and other dairy products, which is a critical health concern for humans. Traditional approaches, including the diagnosis and treatment of mastitis and improving sanitary conditions, have not achieved satisfactory results in controlling this disease. Consequently, current research priorities emphasize the development of tools for the rapid and accurate diagnosis of mastitis, along with strategies to enhance udder health in cows. These advancements are essential to ensure high milk production, which remains a determining factor in the profitability of dairy farming. The most common causes are bacteria, which are classified into contagious and environmental categories. Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Escherichia coli, and Klebsiella pneumoniae are the most common pathogens associated with mastitis. Mastitis resistance is a complex trait influenced by multiple genes. Given the rise in antimicrobial resistance, the development of alternative treatments for bovine mastitis is crucial. Advances in next-generation sequencing technologies provide an opportunity to elucidate the genetic mechanisms underlying mastitis. This study aims to investigate network-based approaches and identify hub genes to gain deeper insights into the genetic control of this disease.
Materials and Methods: The samples for gene expression analysis included 6 biological replicates of milk from healthy cows and 6 replicates of milk from cows with mastitis in the German Holstein population. which were obtained from the GSE93082 dataset in the GEO database. GEO2R was used for quality control of sequencing and gene expression analysis. Two criteria (|log2 fold-change (FC)| > 2) and adj p-value < 0.05 were used to identify differentially expressed genes. To identify gene ontology and pathways, DAVID was used. Gene Ontology (GO) provides a standard framework for classifying gene functions globally. In this study, we used GO to understand the roles and functions of genes. Genes are categorized into three groups based on ontology: BP (Biological Processes), MF (Molecular Functions), and CC (Cellular Components). These components respectively include biological processes, molecular functions, and cellular components. Finally, to identify hub genes, the DEGREE method of the CytoHubba plugin in Cytoscape software was used.
Results: In total, 707 genes exhibited differential expression, with 271 genes showing low expression and 436 genes showing high expression when comparing healthy and infected samples. which had a close association with mastitis. Among these, 10 genes including IL1B, TLR4, STAT1, STAT3, ICAM1, TLR2, CD44, MYD88, and PTGS2 were identified as hub genes based on the DEGREE method. Analysis of the identified genes revealed 99 pathways related to mastitis, of which 20 pathways with P-Value<0.05 are highlighted in the chart. The analysis of the identified pathways showed that the TNF signaling pathway, which is activated in response to inflammation and infection, the TLR signaling pathway, where Toll-like receptors (TLR) play a role in recognizing pathogens (such as bacteria), and the IL-17 signaling pathway, which is an inflammatory cytokine and plays a role in response to bacterial and fungal infections, were significant. This pathway can attract neutrophils and other immune cells to the site of infection, and Th17 cells, which play a role in response to bacterial and fungal infections and enhance inflammation by producing IL-17, have a more significant functional role in bovine mastitis. The Gene Ontology (GO) analysis showed that in bovine mastitis, processes related to inflammation, immune response, and regulation of cell death (apoptosis) are highly active. Additionally, cellular components such as the endoplasmic reticulum and mitochondria, as well as molecular activities like cytokine binding and antioxidants, play a significant role in the response to infection and inflammation. These findings indicate that cells are working to combat infection and reduce tissue damage in the bovine mammary gland.
Conclusion: The identification of multiple pathways related to mastitis and the ontology of candidate genes has shown that mastitis is a highly complex trait influenced by various factors. These findings highlight the significant importance of the identified genes in understanding the biological mechanisms of bovine mastitis. The highlighted genes in this study can serve as biomarkers for mastitis. In addition, these loci may contain different nucleotide variants that could be used for the genetic improvement and designing of breeding strategies against mastitis in dairy cows.
Introduction and Objective: Bovine mastitis is one of the most important diseases in dairy herds worldwide, affecting cows during dry and lactation periods and causing significant economic losses. This disease is considered the most cost disease in dairy cows globally. Given the economic importance of this issue, numerous research efforts have focused on developing practical and effective methods for preventing mastitis. Additionally, bovine mastitis caused by infectious agents, such as bacteria, can be transmitted to humans through milk and other dairy products, which is a critical health concern for humans. Traditional approaches, including the diagnosis and treatment of mastitis and improving sanitary conditions, have not achieved satisfactory results in controlling this disease. Consequently, current research priorities emphasize the development of tools for the rapid and accurate diagnosis of mastitis, along with strategies to enhance udder health in cows. These advancements are essential to ensure high milk production, which remains a determining factor in the profitability of dairy farming. The most common causes are bacteria, which are classified into contagious and environmental categories. Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Escherichia coli, and Klebsiella pneumoniae are the most common pathogens associated with mastitis. Mastitis resistance is a complex trait influenced by multiple genes. Given the rise in antimicrobial resistance, the development of alternative treatments for bovine mastitis is crucial. Advances in next-generation sequencing technologies provide an opportunity to elucidate the genetic mechanisms underlying mastitis. This study aims to investigate network-based approaches and identify hub genes to gain deeper insights into the genetic control of this disease.
Materials and Methods: The samples for gene expression analysis included 6 biological replicates of milk from healthy cows and 6 replicates of milk from cows with mastitis in the German Holstein population. which were obtained from the GSE93082 dataset in the GEO database. GEO2R was used for quality control of sequencing and gene expression analysis. Two criteria (|log2 fold-change (FC)| > 2) and adj p-value < 0.05 were used to identify differentially expressed genes. To identify gene ontology and pathways, DAVID was used. Gene Ontology (GO) provides a standard framework for classifying gene functions globally. In this study, we used GO to understand the roles and functions of genes. Genes are categorized into three groups based on ontology: BP (Biological Processes), MF (Molecular Functions), and CC (Cellular Components). These components respectively include biological processes, molecular functions, and cellular components. Finally, to identify hub genes, the DEGREE method of the CytoHubba plugin in Cytoscape software was used.
Results: In total, 707 genes exhibited differential expression, with 271 genes showing low expression and 436 genes showing high expression when comparing healthy and infected samples. which had a close association with mastitis. Among these, 10 genes including IL1B, TLR4, STAT1, STAT3, ICAM1, TLR2, CD44, MYD88, and PTGS2 were identified as hub genes based on the DEGREE method. Analysis of the identified genes revealed 99 pathways related to mastitis, of which 20 pathways with P-Value<0.05 are highlighted in the chart. The analysis of the identified pathways showed that the TNF signaling pathway, which is activated in response to inflammation and infection, the TLR signaling pathway, where Toll-like receptors (TLR) play a role in recognizing pathogens (such as bacteria), and the IL-17 signaling pathway, which is an inflammatory cytokine and plays a role in response to bacterial and fungal infections, were significant. This pathway can attract neutrophils and other immune cells to the site of infection, and Th17 cells, which play a role in response to bacterial and fungal infections and enhance inflammation by producing IL-17, have a more significant functional role in bovine mastitis. The Gene Ontology (GO) analysis showed that in bovine mastitis, processes related to inflammation, immune response, and regulation of cell death (apoptosis) are highly active. Additionally, cellular components such as the endoplasmic reticulum and mitochondria, as well as molecular activities like cytokine binding and antioxidants, play a significant role in the response to infection and inflammation. These findings indicate that cells are working to combat infection and reduce tissue damage in the bovine mammary gland.
Conclusion: The identification of multiple pathways related to mastitis and the ontology of candidate genes has shown that mastitis is a highly complex trait influenced by various factors. These findings highlight the significant importance of the identified genes in understanding the biological mechanisms of bovine mastitis. The highlighted genes in this study can serve as biomarkers for mastitis. In addition, these loci may contain different nucleotide variants that could be used for the genetic improvement and designing of breeding strategies against mastitis in dairy cows.
Type of Study: Research |
Subject:
ژنتیک و اصلاح نژاد دام
Received: 2025/03/22 | Accepted: 2025/11/2
Received: 2025/03/22 | Accepted: 2025/11/2
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