Milk miRNA expression in buffaloes as a potential biomarker for mastitis

BACKGROUND

Buffaloes have the highest potential for production due to a promising gene pool that is being enhanced and upgraded. Mastitis is a significant health impediment that greatly diminishes milk yield and quality, affecting rural farmers' livelihoods. The traditional gold standard used for diagnosing mastitis or subclinical mastitis is CMT, but it has the drawback of false positive or negative results. Subclinical mastitis, if not treated promptly, can lead to mammary tumors. To address the gap in early diagnosis of subclinical mastitis in CMT-negative milk of buffaloes, we performed a retrospective analysis and evaluated the milk miRNA expression profiles as potential biomarkers.

RESULTS

Thirty buffalo milk samples based on clinical signs and CMT were divided into normal, subclinical, and clinical mastitis. SCC evaluation showed significant differences between the groups. The data analysis demonstrated that the elevation of miR-146a and miR-383 differed substantially between normal, subclinical, and clinical mastitis milk of buffaloes with 100% sensitivity and specificity. The relationship of SCC with miR-146a and miR-383 in normal/healthy and subclinical mastitis was positively correlated.

CONCLUSION

The overexpression of miR-146a and miR-383 is associated with inflammation. It can be a valuable prognostic and most sensitive biomarker for early mastitis detection in buffaloes with SCC below 2 lakhs and CMT-ve, enhancing the accuracy of subclinical mastitis diagnosis.

Droplet digital PCR quantification of selected microRNAs in raw mastitic cow's milk from the west of Poland

Introduction

MicroRNAs (miRNAs), a class of noncoding small RNAs, have been recognised as potential biomarkers of mammary gland conditions, including bovine mastitis diagnosis. The aim of this study was to quantify selected miRNAs in the milk of mastitic cows.

Material and Methods

Milk samples (n = 90) were collected from healthy and mastitic dairy cows originating from local dairy cattle farms located in the west of Poland. MicroRNAs of the miR-21a, miR-92a, miR-146a and miR-383 species were quantified using the highly sensitive droplet digital PCR method. Direct measurement of somatic cell count (SCC) was performed using a cell counter. Cows were divided into three groups: those with an SCC below 200,000/mL were designated Low (n = 25), those with an SCC between 200,000 and 999,999 were Medium (n = 34), and those with an SCC of 1,000,000 or higher were High (n = 31). Microbiological analyses were performed using standard culture testing.

Results

The level of miR-383 was very low and this miRNA was excluded from analysis. The miR-92a was used to normalise miR-21a and miR-146a expression levels. The obtained results of expression of miR-21a and miR-146a correlated with somatic cell number (R = 0.53 and 0.79, respectively).

Conclusion

These results show that ddPCR is a useful method for quantifying miRNAs in raw cow milk. It seems that miR-146a is a promising marker for bovine mastitis, although further studies are needed to select a panel of miRNAs that can be used in mastitis monitoring in Poland.

Micro RNA differential expression profile in canine mammary gland tumor by next generation sequencing

Canine mammary gland tumors are very common and represent a potential model of human breast cancer, and microRNA (miRNAs) are promising biomarkers and therapeutic targets for these tumors. Accordingly, we aimed to identify miRNAs differentially expressed in canine mammary gland tumors using next generation sequencing (NGS), with subsequent confirmatory qPCR and target gene analyses. Mammary gland tissue was collected from healthy dogs (n=7) and dogs with suspected tumors (n=80). A subset of samples was analyzed with NGS to identify differentially expressed miRNAs with CLC Genome Workbench. Normal (n=10), tumor-adjacent (n=6), and tumor-bearing (n=76) mammary gland tissue samples were analyzed for the identified miRNAs using qPCR. An in silico analysis (TargetScan) was performed to predict the miRNAs' target genes using gene ontology (GO) terms and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database (DAVID). We identified four miRNAs (cfa-miR-1-3p, cfa-miR-133a-3p, cfa-miR-133b-3p, and cfa-miR-133c-3p) as down regulated in canine mammary gland tumor tissues relative to normal and tumor adjacent tissues. KEGG analysis revealed the potential target genes of cfa-miR-1-3p are related to the Rap1 signaling pathway, adherens junction, and Ras signaling pathway, and those of the miR-133 family are related to the TGF-beta signaling pathway, synaptic vesicle cycle, and sphingolipid signaling pathway. In combination, these target genes are related to the regulation of transcription and DNA binding transcription (GO analysis), and the Hippo signaling pathway, adherens junction, and endocytosis (KEGG analysis). Accordingly, we suggest these four miRNAs are promising potential biomarker candidates for canine mammary gland tumors warranting further investigation.

miR-142-5p regulates lipopolysaccharide-induced bovine epithelial cell proliferation and apoptosis via targeting BAG5

Bovine mastitis is a threat to the health of the dairy cow. MicroRNAs (miRs) serve an important role in the progression of bovine mastitis, regulating immune and defense responses. The present study aimed to investigate the possible effects and mechanisms of bovine mastitis underlying miR-142-5p and Bcl-2 associated athanogene 5 (BAG5) in in vitro lipopolysaccharide (LPS)-induced models. Reverse transcription-quantitative PCR and western blotting were performed to determine mRNA and protein expression levels, respectively. ELISAs were conducted to assess the levels of cytokines and an immunofluorescence assay was performed to determine the expression of BAG5. Cell Counting Kit-8, clone formation and 5-ethynyl-2'-deoxyuridine assays were conducted to determine cell viability and proliferation of bovine mammary epithelial MAC-T cells, respectively. Flow cytometry was performed to measure MAC-T cell cycle distribution and apoptosis, and a luciferase assay was conducted to verify whether BAG5 was a target of miR-142-5p. The results indicated that miR-142-5p was upregulated in MAC-T cells treated with LPS compared with the control group. miR-142-5p mimics transfection significantly activated the cytokines TNF-α, IL-1β, IL-6 and IL-8, and significantly increased the expression levels of NF-κB signaling pathway-related proteins in LPS-treated cells. The luciferase activity of MAC-T cells treated with miR-142-5p mimics and BAG5 3'untranslated region wild type decreased, compared with mutant type. By contrast, BAG5 overexpression significantly downregulated the levels of cytokines, including TNF-α, IL-1β, IL-6 and IL-8, in LPS-treated cells. BAG5 overexpression significantly promoted cell proliferation and viability, decreased apoptosis, and regulated Caspase-3, Caspase-9, Bcl-2 and Bax expression in LPS-treated MAC-T cells, which was significantly reversed by transfection with miR-142-5p mimics. In conclusion, the results of the present study suggested that miR-142-5p may promote the progression of bovine mastitis via targeting BAG5. Therefore, the present study provided the foundations for future investigations.

Bovine serum miR-21 expression affected by mastitis

The expression levels of circulating microRNAs (miRNAs) can be affected by disease. The miRNA released from cells within exosomes can act as a remote communication tool and can participate in inflammatory response regulation. Therefore, circulating miRNA has the potential to be an indicator of local disease. The objective of this study was to investigate the serum level of bovine mastitis-related miRNAs. We found that miR-16 expression in serum was affected by hemolysis. The expression levels of miR-21 in serum were increased significantly in cows with mastitis compared with unaffected controls; however, the expression levels of miR-146a, miR-155, miR-222 and miR-383 in cows with mastitis were unchanged. We further verified the upregulation of miR-21 in the serum of cows with mastitis using a digital PCR system. Although the sensitivity and specificity of miR-21 in the serum to detect bovine mastitis was inferior to miRNA biomarkers in the milk, the significant increase of miR-21 in serum may reflect the impact of local inflammation on the systemic reaction.

Bovine milk transcriptome analysis reveals microRNAs and RNU2 involved in mastitis

Mastitis is a common inflammatory infectious disease in dairy cows. To understand the microRNA (miRNA) expression profile changes during bovine mastitis, we undertook a genome-wide miRNA study of normal milk and milk that tested positive on the California mastitis test for bovine mastitis (CMT+). Twenty-five miRNAs were differentially expressed (23 miRNAs upregulated and two downregulated) during bovine mastitis relative to their expression in normal milk. Upregulated mature miR-1246 probably derived from a U2 small nuclear RNA rather than an miR-1246 precursor. The significantly upregulated miRNA precursors and RNU2 were significantly enriched on bovine chromosome 19, which is homologous to human chromosome 17. A gene ontology analysis of the putative mRNA targets of the significantly upregulated miRNAs showed that these miRNAs were involved in binding target mRNA transcripts and regulating target gene expression, and a Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the upregulated miRNAs were predominantly related to cancer and immune system pathways. Three novel miRNAs were associated with bovine mastitis and were relatively highly expressed in milk. We confirmed that one of the novel mastitis-related miRNAs was significantly upregulated using a digital PCR system. The differentially expressed miRNAs were involved in human cancers, infections, and immune-related diseases. The genome-wide analysis of miRNA profiles in this study provides insight into bovine mastitis and inflammatory diseases. DATABASES: The miRNAseq generated for this study can be found in the Sequence Read Archive (SRA) under BioProject Number PRJNA421075 and SRA Study Number SRP126134 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA421075).

Deep RNA-Seq reveals miRNome differences in mammary tissue of lactating Holstein and Montbéliarde cows

Background

Genetic polymorphisms are known to influence milk production and composition. However, the genomic mechanisms involved in the genetic regulation of milk component synthesis are not completely understood. MicroRNAs (miRNAs) regulate gene expression. Previous research suggests that the high developmental potential of the mammary gland may depend in part on a specific miRNA expression pattern. The objective of the present study was to compare the mammary gland miRNomes of two dairy cow breeds, Holstein and Montbéliarde, which have different mammogenic potentials that are related to differences in dairy performance.

Results

Milk, fat, protein, and lactose yields were lower in Montbéliarde cows than in Holstein cows. We detected 754 distinct miRNAs in the mammary glands of Holstein (n = 5) and Montbéliarde (n = 6) midlactating cows using RNA-Seq technology, among which 738 were known and 16 were predicted miRNAs. The 25 most abundant miRNAs accounted for 90.6% of the total reads. The comparison of their abundances in the mammary glands of Holstein versus Montbéliarde cows identified 22 differentially expressed miRNAs (P_adj ≤ 0.05). Among them, 11 presented a fold change ≥2, and 2 (miR-100 and miR-146b) were highly expressed. Among the most abundant miRNAs, miR-186 is known to inhibit cell proliferation and epithelial-to-mesenchymal transition.

Data mining showed that 17 differentially expressed miRNAs with more than 20 reads were involved in the regulation of mammary gland plasticity. Several of them may potentially target mRNAs involved in signaling pathways (such as mTOR) and lipid metabolism, thereby indicating that they could influence milk composition.

Conclusion

We found differences in the mammary gland miRNomes of two dairy cattle breeds. These differences suggest a potential role for miRNAs in mammary gland plasticity and milk component synthesis, both of which are related to milk production and composition. Further research is warranted on the genetic regulation of miRNAs and their role in milk synthesis.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5987-4) contains supplementary material, which is available to authorized users.

Milk MicroRNAs in Health and Disease

MicroRNAs are small noncoding RNAs responsible for regulating 40% to 60% of gene expression at the posttranscriptional level. The discovery of circulating microRNAs in several biological fluids opened the path for their study as biomarkers and long-range cell-to-cell communication mediators. Their transfer between individuals in the case of blood transfusion, for example, and their high enrichment in milk have sparked the interest for microRNA transfer through diet, especially from mothers to infants during breastfeeding. The extension of such paradigm led to the study of milk microRNAs in the case of cow or goat milk consumption in adults. Here we provide a comprehensive critical review of the key findings surrounding milk microRNAs in human, cow, and goat milk among other species. We discuss the data on their biological properties, their use as disease biomarkers, their transfer between individuals or species, and their putative or verified functions in health and disease of infants and adult consumers. This work is based on all the literature available and integrates all the results, theories, debates, and validation studies available so far on milk microRNAs and related areas of investigations. We critically discuss the limitations and outline future aspects and avenues to explore in this rapidly growing field of research that could impact public health through infant milk formulations or new therapies. We hope that this comprehensive review of the literature will provide insight for all teams investigating milk RNAs' biological activities and help ensure the quality of future reports.

Inflammation-related microRNA expression level in the bovine milk is affected by mastitis

MicroRNA (miRNA) in tissue and liquid samples have been shown to be associated with many diseases including inflammation. We aimed to identify inflammation-related miRNA expression level in the bovine mastitis milk. Expression level of inflammation-related miRNA in milk from mastitis-affected and normal cows was analyzed using qPCR. We found that expression level of miR-21, miR-146a, miR-155, miR-222, and miR-383 was significantly upregulated in California mastitis test positive (CMT+) milk. We further analyzed these miRNA using a chip-based QuantStudio Digital PCR System. The digital PCR results correlated with those of qPCR, demonstrating upregulation of miR-21, miR-146a, miR-155, miR-222, and miR-383 in CMT+ milk. In conclusion, we identified miRNA that are upregulated in CMT+ milk. These miRNA exhibited sensitivity and specificity greater than 80% for differentiating between CMT+ milk and normal milk. Our findings suggest that inflammation-related miRNA expression level in the bovine milk was affected by mastitis, and miRNA in milk have potential for use as biomarkers of bovine mastitis.