Effect of tropical thermal stress on peri-implantation immune responses in cows

Identification of circulatory microRNA based biomarkers for early pregnancy diagnosis in buffalo

Introduction: The most crucial factor in improving animal reproduction efficiency is early pregnancy diagnosis. Early diagnosis not only reduces the time interval between two calvings but also aids farmers in identifying open animals, thereby preventing significant milk production losses. Therefore, the objective of this study was to discover circulatory miRNAs that would be useful for early pregnancy diagnosis in buffalo. Material and methods: Blood samples were taken on 0, 6th, 12th, and 18th day after artificial insemination from pregnant animals (n = 30) and non-pregnant animals (n = 20). During these stages of pregnancy, total RNA was extracted, and a small RNA library was subsequently generated and sequenced on the Illumina platform. Subsequently, Real-time PCR was used to validate the findings. Results and discussion: There were 4,022 miRNAs found during the pregnancy, with 15 of those lacking sequences and 4,007 having sequences already in the database. From the beginning of pregnancy until the 18th day, 25 of these miRNAs showed a substantial shift in expression levels in the maternal blood, with a change more than two logs. Furthermore, based on qPCR results, 19 miRNAs were found to be more abundant in pregnant animals than in non-pregnant animals. We used target prediction analysis to learn how maternally expressed miRNAs relate to fetal-maternal communication. In conclusion, miRNA based biomarkers that could be associated with the diagnosis of pregnancy were identified including miR-181a and miR-486 highly upregulated on the 18th day of pregnancy. This study also provides a comprehensive profile of the entire miRNA population in maternal buffalo blood during the early stages of pregnancy.

Temporal analysis of circulating nucleic acid in early days of pregnancy in buffalo

Improving reproductive efficiency in livestock relies mainly on the ability to detect pregnancy quickly and accurately. Recently, circulating nucleic acids (CNAs) have been exploited for prenatal diagnosis in humans and animals. In the current investigation, serum samples were collected from pregnant animals (n = 30) and non-pregnant animals (n = 20) on 0th, 6th, 12th, and 18th day post artificial insemination. Total DNA was isolated from these serum samples. Two CNA tags (Bov-B and ART2A) derived from repetitive sections of the bovine genome were amplified using DNA extracted from serum samples. The expression analysis of these CNAs was done using real-time polymerase chain reaction assay, and copy number of each tag was calculated in pregnant and non-pregnant animals. The average number of copies of Art2A increased approximately threefold (P < 0.01) from day zero of pregnancy (7,000 copies) to the day 18 of pregnancy (> 21,000). Similarly, BovB levels in the pregnant group increased significantly (approximately 2.9-fold) from day zero (93,900 copies) till day 18 (> 2, 72,310 copies) (P < 0.01). There was no significant change observed on the 6th and 12th day of pregnancy and on the 18th day in the non-pregnant animals. In conclusion, based on these findings, the defined cut-off value can distinguish between pregnant and non-pregnant animals with a sensitivity of nearly 80% and specificity of nearly 70%. It is possible to employ these two CNA tags as biomarkers for early detection of pregnancy in buffaloes.

Interferon-Stimulated Gene Expression in Peripheral Blood Leucocytes as a Convenient Prediction Marker for Embryo Status in Embryo-Transferred Japanese Black Cows during the Peri-Implantation Period

Pregnancy diagnosis during early gestation is important for cattle reproduction. The expression of interferon-stimulated genes (ISGs) in peripheral blood leukocytes (PBLs) was studied in embryo-transferred (ET) Japanese Black cattle. ISGs in PBLs-ISG15, MX1, MX2, and OAS1-were detected in multiple ovulation ET cattle using a real-time quantitative polymerase chain reaction, and receiver operating characteristic (ROC) curve analysis was performed. Gestational status was predicted using the average ISG levels during the normal estrous cycle (AVE) and the Youden index from the ROC curve analysis as cutoff values. The ISG15, MX1, and MX2 levels were significantly higher in pregnant cattle (n = 10) than in non-pregnant cattle (n = 23) on gestation day 21, whereas the levels of all ISGs were similar between non-pregnant and non-pregnant cattle with late embryonic death (n = 7). ISG15, MX1, and MX2 appropriately predicted the gestational status of ET cows. The statistical evaluation of the diagnostic accuracy in ET cows on day 21 of gestation presented higher values of sensitivity, specificity, accuracy, and positive predictive values of ISG15, MX1, and MX2 using the Youden index than using the AVE. Therefore, ISG15, MX1, and MX2 are excellent biomarkers of gestational status during the peri-implantation period in ET cattle.

Heat stress modulates polymorphonuclear cell response in early pregnancy cows: I. interferon pathway and oxidative stress

One of the major causes of early pregnancy loss is heat stress. In ruminants, interferon tau (IFNT) is the embryo signal to the mother. Once the interferon signaling pathway is activated, it drives gene expression for interferon-stimulated genes (ISGs) and alters neutrophils responses. The aim of the present study was to evaluate interferon (IFN) pathway, ISGs and gene expression in polymorphonuclear leukocytes (PMN) and oxidative stress in dairy cows under heat stress. Pregnant cows had their estrous cycle synchronized and randomly assigned to a comfort or heat stress group. Blood samples were collected at artificial insemination (AI) and on Days 10, 14 and 18 following AI. Pregnant cows were pregnancy checked by ultrasound on Day 30 and confirmed on Day 60 post-AI. Results are presented as mean ± SEM. The corpus luteum (CL) diameter was not different between groups of pregnant cows; concentration of progesterone of pregnant cows on Day 18 following AI was greater in comfort group compared to heat stressed group. Comfort pregnant cows had higher expression of all analyzed genes from interferon pathway, except for IFNAR1, on both Days 14 and 18. Conversely, heat stressed cows did not show altered expression of IFNT pathway genes and ISGs between Days 10, 14, and 18 after AI. The oxidative stress, determined as malondialdehyde (MDA) levels, was greater in heat stress group on Days 10, 14 and 18, independent of pregnancy status. Heat stress negatively influences expression of ISGs, IFN pathway gene expression in neutrophils, and oxidative stress. Our data suggest that lower conception rates in cows under heat stress are multifactorial, with the association of interferon pathway activation and the unbalanced oxidative stress being main contributing factors.

JAK3 and PI3K mediates the suppressive effects of interferon tau on neutrophil extracellular traps formation during peri-implantation period

Interferon tau (IFNτ) is the main maternal signal for pregnancy in ruminants and modulates the functions of various immune cells, including neutrophils. Neutrophil extracellular traps (NETs) are one of the main defence mechanisms of neutrophils. In this study, we observed higher (p < 0.01) ex-vivo NETs extrusion by blood neutrophils from day 16-18 post artificial insemination (AI) in non-inseminated and inseminated non-pregnant cows compared to pregnant cows. In vitro study also showed that IFNτ hampers NETs formation in dose and time dependent manner. The lowest (p < 0.01) NETs formation and the highest (p < 0.01) mRNA expression (RT-PCR) of IFNτ stimulated genes (ISG15, OAS1, MX1) were observed when neutrophil incubated with 9 ng/mL IFNτ for 3.5 h. Signalling cascades mediating IFNτ impairment of NETs formation were identified using inhibitors of JAK2, JAK3, p38, PI3K/Akt and MAPK/Erk. IFNτ reduced (p < 0.01) the mRNA expression (RT-PCR) and concentration (ELISA) of genes and proteins that mediate NETs formation in blood neutrophils including histones (H1, H2), neutrophil elastase (NE) and myeloperoxidase (MPO). However, the effects of IFNτ on these genes and proteins were eliminated in the presence of JAK3 or PI3K inhibitors. Immunocytochemistry study also showed strong MPO signal in the presence of JAK3 or PI3K inhibitors as compared to positive control (PC, IFNτ alone). The results indicate that IFNτ impairs NETs formation using JAK3 and PI3K and thus essential for successful implantation and establishment of pregnancy in cows.

Peripartum changes in the activity and expression of neutrophils may predispose to the postpartum occurrence of metritis in dairy cows

Metritis is a postpartum uterine pathology that causes a huge economic loss due to increased culling risk and impaired milk yield and reproduction in cows. The present study was carried out to study the changes in the activity and expression of blood neutrophils in crossbred dairy cows with and without metritis. Collection of blood samples was done at -3, -2 and - 1 weeks before calving, at calving and during the first day of metritis diagnosis in metritis group (n = 8) or at day 8-10 post calving in healthy group (n = 8). Neutrophils were studied for its percentage (microscopically), respiratory burst (nitro blue tetrazolium assay), myeloperoxidase (MPO) concentrations (sandwich ELISA) and expression of CXCR1, CXCR2, TLR2, TLR4, GRα, CD11b, CD14, CD25, CD44, CD47 and CD62L (RT-PCR). Immunocytochemistry was used to investigate MPO concentration and CD14 activity, and western blotting was used for estimating MPO. Although most of these parameters changed in the cows that developed metritis one week before calving, MPO and CD14 got altered much earlier. Myeloperoxidase concentrations and expression of CD14 were considerably lower starting from -2 weeks before calving in cows that developed metritis compared to healthy cows. Further studies are warranted to study the possible use of MPO and CD14 to identify transition cows more vulnerable to develop metritis several weeks before disease occurrence.

Evaluation of Interleukin-10 and Pro-inflammatory Cytokine Profile in Calves Naturally Infected with Neonatal Calf Diarrhea Syndrome

Multifactorial neonatal calf diarrhea (NCD) is one of the main causes of mortality in calves under 1 month of age. Studies have shown that pro-inflammatory cytokines (i.e., interleukin (IL)-1&amp;beta;, IL-6, and tumor necrosis factor-alpha [TNF-&amp;alpha;]) can increase in many pathophysiological conditions. In addition, IL-10 as one of the most important anti-inflammatory cytokines contributes to the inhibition of pro-inflammatory cytokines. Few studies have addressed cytokine levels in calves with NCD. Therefore, the goal of this study was to evaluate the plasma concentrations of pro-inflammatory cytokines, as well as IL-10, in the calves naturally infected with NCD syndrome. For this purpose, 87 neonatal calves were monitored for 1 month. Out of this population, 10 cases were diagnosed with NCD and studied as the case group. In addition, a control group was considered that consisted of 10 age- and gender-matched neonatal calves without any diseases. From each calf, 5 ml blood sample was collected into EDTA tubes by jugular venipuncture. The samples were then centrifuged, and the extracted plasmas were aliquoted and stored at -20 &amp;deg;C. Finally, the plasma concentrations of pro-inflammatory cytokines (i.e., IL-1&amp;beta;, IL-6, and TNF-&amp;alpha;) and anti-inflammatory cytokine IL-10 were measured using the ELISA kits based on the manufacturer&amp;#39;s protocols. The results showed that the plasma concentrations of pro-inflammatory cytokines were significantly higher in the case group than in the control group. However, no significant difference was found between the two groups in terms of the plasma concentrations of IL-10. This study indicates that pro-inflammatory cytokines could be used to recognize the immune system response to NCD.

Proteomics and transcriptomics study reveals the utility of ISGs as novel molecules for early pregnancy diagnosis in dairy cows

An early and precise diagnosis of pregnancy in cows is critical to short the calving interval and to improve their reproductive efficiency. Neutrophils are the first blood cells to sensitize the embryo in the uterus and participate in maternal recognition of pregnancy after getting induced by interferon tau (IFNτ). To study the protein abundance ratio, blood samples were collected on 0th, 10th, 18th and 36th day post-artificial insemination (AI) from crossbred Karan Fries cows. Neutrophils were isolated through density gradient centrifugation and studied for protein abundance by high-performance liquid chromatography coupled with mass spectrometry (LC-MS). Protein abundance ratios for Myxovirus resistance (MX1 and MX2) were found to be higher (P < 0.05) on day 10 and day 18 post-AI, whereas Oligoadenylate synthetase-1 (OAS1) and Interferon stimulated gene-15 ubiquitin-like modifier (ISG15) proteins were more abundant on day 18 post-AI. The relative mRNA expressions of these molecules were also studied by qPCR. The gene expression of ISG15, MX1, MX2 and OAS1 was found to be higher (P < 0.05) on day 10th, 18th and 36th post-AI compared to day 0. The study indicates that ISGs on blood neutrophils are essential for the establishment of pregnancy and may be targeted as potential biomarkers for pregnancy diagnosis in cows.

Immunological detection of pregnancy: Evidence for systemic immune modulation during early pregnancy in ruminants

Mammalian pregnancy creates unique challenges for immune systems highly evolved to detect and eliminate invading pathogens. Recognition of the challenges created by gestating a semi-allogeneic fetus evolved from the discipline of transplantation biology and were informed by studies on the unique natural parabiosis that occurs when female calves are gestated with twin male fetuses. These pregnancies typically result in an intersex female termed a freemartin, which revealed insights into development of the male and female reproductive tracts. However, they also uncovered important clues on immune tolerance with wide-ranging implications to reproductive biology, transplantation biology and autoimmune disease. Many studies focused on identifying mechanisms through which the fetus evades maternal immune detection and elimination. These included studies characterizing immune interactions between the fetus and mother at the nourishing interface of the placenta and uterine endometrium. This immunological forbearance only occurs under high concentrations of circulating progesterone. Beyond the requirement for progesterone, there has been considerable progress towards understanding the effects of conceptus signals on maternal immune function. One common theme is that pregnancy induces a T helper 2 immune bias as shown in several mammalian species, including domestic ruminants. However, a growing body of evidence shows that the fetus not only evades, but also provokes immune responses locally in the uterus and in peripheral tissues. This is perhaps most dramatically illustrated by domestic ruminants where the conceptus secretes a unique interferon in the opening salvo of hormonal communication with the maternal immune system. The role of interferon tau in regulating expression of genes of the innate immune system in the uterus has been extensively studied. More recently, it was determined that these same genes are also induced in peripheral immune cells and other tissues throughout the body. In addition to interferon tau and progesterone, pregnancy associate glycoproteins and chaperonin 10 (aka Early Pregnancy Factor) are implicated in altering immune function both locally and systemically during pregnancy. While it is tempting to speculate that this activation of innate immunity is designed to counteract selective immunosuppression, knowledge of the importance of local and systemic immune activation to the success of pregnancy remains incomplete. This area remains fertile ground for developing better approaches to diagnose and treat infertility in domestic farm species and humans alike.

Heat Stress Impairs the Physiological Responses and Regulates Genes Coding for Extracellular Exosomal Proteins in Rat

Heat stress (HS) is challenging in humans and animals as it is a complicated regulatory mechanism. This prompted us to characterize the physiological and molecular responses of a HS-animal model. In this study, a rat model system was developed by using three temperature treatments (40 ℃, 42 ℃, and 43 ℃) and sixteen biochemical indicators in blood at 42 ℃ for 30 min (H30), 60 min (H60), and 120 min (H120). In addition, transcriptomic profiling was carried out in H120-rats’ blood, liver, and adrenal gland samples for detection of the genes of interest. Our findings demonstrated that the adrenocorticotropic hormone, catalase, prolactin, growth hormone, and lactic acid have significant spatiotemporal variation in the H120-rats as compared with the control. Furthermore, through transcriptomic screening, we documented a high ratio of differentially expressed genes (DEGs) in adrenal glands, liver, and blood, respectively. Among them, Nup153, Plxnb2, Stx7, Hspa9, Chordc1, Pde4d, Gm2α, and Rnf125 were associated with the regulation of HS and immune response processes. Notably, 36 and 314 of DEGs in blood and adrenal glands were detected in the composition of the extracellular exosome, respectively. Furthermore, the correlation analysis between gene transcripts and biochemical indicator levels identified the Lgals3, S1006, Fn1,F2, and Kng1l1 as key candidate genes for HS encoding extracellular exosomal proteins. On the basis of our results, it was concluded that the current rat model provides a molecular basis for future research in HS resistance in humans and livestock.

Potential roles of neutrophils in maintaining the health and productivity of dairy cows during various physiological and physiopathological conditions: a review

Neutrophils represent the first line of innate immunity and are the most prominent line of cellular defence against invading microorganisms. On stimulation, they can quickly move through the walls of veins and into the tissues of the body to immediately attack or monitor the foreign antigens. Neutrophils are highly versatile and sophisticated cells which are endowed with highly sensitive receptor-based perception systems. They were traditionally classified as short-lived phagocytes actively involved during infection and inflammation, but recently, it has been seen that neutrophils are capable of detecting the presence of sperms during insemination as well as an implanting embryo in the female reproductive tract. These specialised phagocytes play a major role in tissue remodelling and wound healing, and maintain homeostasis during parturition, expulsion of placenta, folliculogenesis, corpus luteum formation and luteolysis. Here, we review the role played by neutrophils in maintaining homeostasis during normal and inflammatory conditions of dairy cattle. We have summarised the alteration in the expression of some cell adhesion molecules and cytokines on bovine neutrophils during different physiological and physiopathological conditions. Some emerging issues in the field of neutrophil biology and the possible strategies to strengthen their activity during the period of immunosuppression have also been discussed.

Progesterone Supplementation During the Pre-implantation Period Influences Interferon-Stimulated Gene Expression in Lactating Dairy Cows

This study examined the effect of progesterone (P4) supplementation from Days 16 to 18 post-AI on interferon-stimulated gene (ISG) expression on Day 19 in high-producing dairy cows. Gene expression levels were measured in peripheral blood mononuclear cells. Possible relationships between ISG expression and the incidence of pregnancy failure were also investigated. Cows were alternately assigned on Day 16 post-AI to a control (C: n = 13) or treatment group (P4: n = 14). Out of 27 cows, 12 returned to oestrus before pregnancy diagnosis and 9 were diagnosed as pregnant on Day 28. ISG expression was assessed in all cows. Expression levels for the genes OAS1, ISG15, MX1 and MX2 were higher for pregnant than for non-pregnant cows (P=0.04; P<0.001; P=0.02; P=0.045; respectively). A significant (P=0.01) interaction was observed between the treatment and positive pregnancy diagnosis groups on Day 28 post-AI for the probability of showing ISG expression. This interaction suggests that in cows not pregnant on Day 28, P4 supplementation may have led to increased ISG15 mRNA expression on Day 19. Lower ISG15 expression was detected for cows returning to oestrus than for pregnant cows (P<0.001). However, cows with a negative pregnancy diagnosis showed intermediate values, differences being non-significant when compared to cows returning to oestrus or pregnant cows. Our results suggest that P4 supplementation during the pre-implantation period promotes conceptus signalling.

The GnRH analogue dephereline given in a fixed-time AI protocol improves ovulation and embryo survival in dairy cows

This study compares the fertility effects of inducing ovulation using the GnRH analogue, dephereline, versus natural GnRH at the end of a 5-day progesterone(P4)-based protocol for fixed-time artificial insemination (FTAI) in in heat-stressed and non-heat stressed lactating dairy cows. Cows were given GnRH (GnRH group, n = 369) or dephereline (DEPH group, n = 379) and were inseminated 14-20 h later. Dephereline treatment increased corpus luteum (CL) size on Day 7 post-AI compared with GnRH (P < .0001) while a one-mm increase in CL size was found to give rise to a 1.1-fold increase in the pregnancy rate at FTAI (P = .001). Based on odds ratios, the interaction between treatment and heat stress had a significant effect on the ovulation failure rate (P < .01). This meant that relative to non-heat-stressed GnRH-treated cows, ovulation failure was 2.9 times more likely in heat-stressed GnRH-treated cows (P = .001), 0.3 times less likely in non-heat-stressed DEPH-treated cows (P = .04) and was similar in heat-stressed DEPH-treated cows. Further, non-heat-stressed DEPH-treated cows were more likely to conceive by a factor of 1.6 than the remaining cows (P = .03). Finally, GnRH-treated multiparous cows were 9.9 times more likely to suffer pregnancy loss than the remaining cows (P = .03). Our results indicate that, compared to treatment with GnRH, dephereline reduced the risk of ovulation failure and consequently increased the pregnancy rate under heat stress conditions. In multiparous cows, dephereline treatment also reduced the negative age effect on pregnancy maintenance.

Recombinant interferon stimulated protein 15 (rISG15) as a molecular marker for detection of early pregnancy in Bubalus bubalis

Early and accurate diagnosis of pregnancy in animals is important for improving the reproductive management of livestock. The buffalo (Bubalus bubalis) is the most important dairy animal in India, but there are reproductive problems resulting from extended calving interval and ovulation occurring in the absence of behavioral estrus. The lack of simple methods for early pregnancy diagnosis intensifies these problems. The present study, therefore, was conducted to ascertain the role of the interferon-stimulated gene, (ISG), 15 in pregnancy detection. The anti-ISG15 Mab based ELISA was developed that could be used for detecting pregnancy at 18 to 20 days after artificial insemination (AI). The ISG15 protein was isolated from a pregnant buffalo and was amplified, and cloned in Escherichia coli by using coding region primers. The ISG15 gene was expressed in the host Escherichia coli BL21 (DE3), and the protocol was standardized for optimum gene expression. Using immortal hybridoma (fused myeloma and B cells) cells, a highly specific and sensitive antibody, anti-ISG15 mAb, for detecting ISG15 (protein) in the serum of pregnant buffaloes was obtained. A blocking ELISA was developed using the anti-ISG15 mAb to detect pregnancy in buffalo within 18 to 21 days after AI. The ISG15 gene was upregulated (P <  0.05) in pregnant buffalo at 18 to 21 days of pregnancy. This assay has an overall diagnostic accuracy of 75.0%. It, therefore, is concluded that recombinant ISG15 retains the potential for detecting pregnancy in B. bubalis and may have applications in ELISA kits for pregnancy detection in closely related species.