Expression of interferon-stimulated gene ISG15 and ubiquitination enzymes is upregulated in peripheral blood monocyte during early pregnancy in dairy cattle

Pregnancy influences expression of interferon-stimulated genes, progesterone receptor and progesterone-induced blocking factor in ovine thyroid

OBJECTIVE

Embryonic interferon-tau (IFNT) and progesterone affect expression of interferonstimulated genes (ISGs), progesterone receptor (PGR) and progesterone-induced blocking factor (PIBF) in the ovine thyroid.

METHODS

Thyroids of ewes were sampled at day 16 of nonpregnancy, days 13, 16, and 25 of pregnancy, and real-time quantitative polymerase chain reaction assay, western blot and immunohistochemistry were used to detect expression of ISGs, PGR, and PIBF.

RESULTS

Free ISG15 protein was undetected, but ISG15 conjugated proteins upregulated at day 16 of pregnancy, and expression levels of ISG15 conjugated proteins, PGR isoform (70 kDa), PIBF, interferon-gamma-inducible protein 10 and myxovirusresistance protein 1 peaked, but expression level of signal transducer and activator of transcription 1 was the lowest at day 16 of pregnancy. In addition, the expression levels of PGR isoform (70 kDa) and signal transducer and activator of transcription 1 (STAT1) decreased, but levels of PGR isoform (43 kDa), 2',5'-oligoadenylate synthetase, IP-10 and MX1 increased at day 25 of pregnancy comparing with day 16 of the estrous cycle.

CONCLUSION

Early pregnancy affects expression of ISGs, PGR, and PIBF in maternal thyroid through IFNT and progesterone, which may regulate thyroid autoimmunity and thyroid hormone secretion in ewes.

Supplementation with long-acting injectable progesterone 3 days after TAI impaired luteal function in buffaloes

Three experiments were conducted to evaluate the effects of long-acting injectable progesterone (iP4) in buffalo cows. In Experiment 1, ovariectomized buffaloes received 300 mg (iP300) or 600 mg (iP600) of iP4, and serum P4 concentrations were evaluated. In experiment 2, three groups were compared: control or administration of 300 mg of iP4 3 (iP4-D3) or 6 days (iP4-D6) after timed artificial insemination (TAI). On day 16, reproductive tract was recovered for conceptus, endometrium, and corpus luteum (CL) analysis. In experiment 3, pregnancy per AI (P/TAI) and proportion of pregnancy losses were evaluated after administration of 300 mg of iP4 3 (iP4-D3) or 6 days (iP4-D6) after TAI in lactating buffaloes. In experiment 1, serum P4 concentrations remained over 1 ng/mL for ~ 3 days in both groups. The 300 mg dose was used in subsequent experiments. In experiment 2, CL weight and endometrial glands density were decreased, and conceptus length was increased in iP4-D3 compared to control and to iP4-D6 (P < 0.05). Transcript abundance of Prostaglandin F Receptor (FP) and ISG15 in CL and of ISG15 and MX1 in endometrium was greater in iP4-D3 when compared to control and to iP4-D6 (P < 0.05). In experiment 3, there was no difference among experimental groups for P/TAI at D30 and pregnancy losses (P > 0.1); however, iP4-D3 presented a lower P/TAI at day 60 (41.7%) when compared to control (56.8%) and iP4-D6 (57.7%; P = 0.07). In conclusion, administration iP4 at 3 days after TAI affects CL development and consequently decreases final pregnancy outcome in buffaloes.

Gene expression of pregnancy-associated glycoproteins-1 (PAG-1), interferon-tau (IFNt) and interferon stimulated genes (ISGs) as diagnostic and prognostic markers of maternal-fetal cellular interaction in buffalo cows

The aim of this study was to determine the presence of Pregnancy-associated glycoprotein -1 (PAG-1) mRNA expression in the maternal circulation of pregnant buffaloes during the early stage of pregnancy. Contemporaneously, the mRNA expression levels of Interferon-tau (IFNt) and some Interferon stimulated genes (ISGs) (interferon stimulated gene 15 ubiquitin-like modifier interferon, ISG15; Mixoviruses resistance 1 and 2, MX1 and MX2; 2',5'-oligoadenylate synthase 1,OAS1) were evaluated in order to expand our knowledge of the molecular processes involved in the early stages of pregnancy and to identify potential biomarkers of maternal-fetal cellular interaction in buffalo. The study was conducted on 38 synchronized and artificially inseminated buffalo cows (d 0), divided ex post into 3 groups: Pregnant (n = 17), Non-pregnant (n = 15) and Embryo mortality (n = 6). Blood samples were collected on d 14, 19, 28 and 40 after artificial insemination (AI) for peripheral blood mononuclear cells (PBMCs) isolation. Expression levels of mRNA of PAG-1, IFNt, ISG15. MX1, MX2 and OAS1 were measured using RT-qPCR. No significant changes were observed in IFNt and PAG gene expressions between groups, while significant differences (p < 0.001) were found for ISG15, MX1, MX2, and OAS1. Pairwise comparisons revealed that the differences between groups occurred on days 19 and 28 post-AI. ISG15 proved to have the best diagnostic performance for distinguishing between pregnant animals and animals that experienced embryo mortality with the ROC analysis. According to the results of the univariate analyses, day 19 was identified as the most indicative to discriminate between groups while the most reliable genes for this differentiation were ISG15, MX1 and MX2. MX2 proved to be the best gene for discriminating pregnant buffaloes using the discriminant analysis, while MX1 was the gene that best predicted embryo mortality. Our results showed that among PAG-1, IFNt and ISGs expression as diagnostic and prognostic markers of maternal-fetal cellular interaction in buffalo cows, ISGs proved to be the best peripheral biomarkers for predicting pregnancy and embryonic mortality during the peri-implantation period. These insights into the mechanisms behind maternal-fetal interaction and the development of a method for the early detection of embryo distress may enable us to implement effective strategies to support embryo survival.

Interferon-τ -induced ISG15-AS regulates endometrial receptivity during early goat pregnancy

Endometrial receptivity is a critical process for the successful establishment of pregnancy in ruminants. However, the biological role of long non-coding RNAs (lncRNAs) in the development of endometrial receptivity is poorly understood. In this study, we performed RNA-seq analysis of immortalised goat endometrial epithelial cells (gEECs) treated with interferon-τ (IFNT). Transcriptome profiles showed that 8069 high-confidence putative lncRNAs, including 6498 intronic lncRNA transcripts, 1078 lincRNAs and 493 antisense lncRNAs were identified in gEECs with or without IFNT treatment. Functional clustering analysis was performed by using cis and trans lncRNAs prediction. GO and KEGG analyses revealed that differentially expressed lncRNAs may regulate tissue remodelling and immune responses. Subsequently, six of the 21 differentially expressed antisense lncRNAs were validated using qRT-PCR. Through functional screening and co-expression analysis of lncRNAs in gEECs, we identified that ISG15-AS was mainly expressed in the luminal and glandular epithelium on days 5 and 15 and was strongly upregulated on day 18 of pregnancy in vivo. Similarly, ISG15-AS was abundant in the nucleus and cytoplasm, and was significantly upregulated after treatment with IFNT in gEECs. In addition, ISG15 is an IFNT-responsive gene, that displayed an evident increase in vivo and in vitro. Moreover, sense ISG15 was significantly upregulated following ISG15-AS silencing. The key genes related to ISGylation and endometrial receptivity in gEECs dramatically increased after ISG15-AS inhibition. Collectively, our results indicate that a novel antisense lncRNA, ISG15-AS, may be important in regulating endometrial receptivity through ISGylation.

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.

Feasibility and accuracy of using different methods to detect pregnancy by conceptus-stimulated genes in dairy cattle

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Peripheral blood mononuclear cells (PBMC) are the best biomarker for pregnancy prediction on d 20 after timed AI.

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An abundance of ISG15 was observed in pregnant dairy females in PBMC, total blood leukocytes, and cervical cells.

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Abundance of LGALS3BP is not good biomarker for determination of pregnancy status using any cell type.

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Total milk leukocytes are not useful for detection of genes stimulated by early pregnancy.

Development of new methods for early diagnosis of pregnancy can be important to increase the reproductive efficiency and profitability of dairy herds. The bovine conceptus secretes IFN-τ that stimulates the transcription of several genes in circulating immune cells and extrauterine tissues. The aims of this study were to evaluate the mRNA abundance for pregnancy predictability of a classic gene stimulated by IFN-τ (ISG15) and a novel potential pregnancy marker (LGALS3BP) in peripheral blood mononuclear cells (PBMC), total blood leukocytes (TBL) or milk leukocytes (TML), and cervical cells (CC) on d 20 after timed artificial insemination (TAI) in dairy cattle. Eighteen Holstein females (12 cows and 6 heifers) were submitted to an estrous synchronization protocol for TAI (d 0). On d 20 post-TAI, blood samples were collected from coccygeal vessels for isolation of PBMC and in Tempus Blood RNA tubes (Applied Biosystems) for TBL. Samples of CC were collected using a cytological brush, and the TML were isolated from milk samples collected before routine milking. Pregnancy diagnosis was performed on d 30 post-TAI using transrectal ultrasonography, and females were classified as pregnant (n = 8) or nonpregnant (n = 10). Total RNA was extracted and mRNA abundance of target genes (ISG15 and LGALS3BP) was quantified by reverse-transcription quantitative PCR and normalized in relation to reference genes. Data were analyzed by ANOVA using the MIXED procedure of SAS (SAS Institute Inc.). The mRNA abundance of ISG15 was greater in pregnant than in nonpregnant animals for PBMC, TBL, and CC. No difference was detected for TML based on pregnancy status. For LGALS3BP mRNA abundance, no difference was detected between pregnant and nonpregnant animals for PBMC, TBL, and TML, but a tendency for greater abundance in pregnant animals was observed for CC. The fold change for ISG15 in each pregnant cow related to the mean of nonpregnant animals was 2.73 ± 0.31, 3.40 ± 2.17, 1.64 ± 0.29, and 0.005 ± 0.002 for PBMC, CC, TBL, and TML, respectively. The fold change for LGALS3BP in each pregnant cow related to the mean of nonpregnant animals was 0.97 ± 0.38, 1.77 ± 0.39, 0.20 ± 0.08, and 0.70 ± 0.11 for PBMC, CC, TBL, and TML, respectively. The receiver operating characteristic curve analysis indicated that ISG15 abundance predicted pregnancy in PBMC (area under curve, AUC = 0.92) and CC (AUC = 0.77) but not in TBL (AUC = 0.72) or TML (AUC = 0.52). In conclusion, mRNA abundance for ISG15 in PBMC was the best predictor for pregnancy at d 20 post-TAI, whereas TBL and TML were not good predictors of pregnancy on d 20 post-TAI. The mRNA abundance of LGALS3BP was not associated with pregnancy status in any type of cell evaluated.

Transforming growth factor-β superfamily and interferon-τ in ovarian function and embryo development in female cattle: review of biology and application

Survival of the embryo and establishment of a pregnancy is a critical period in the reproductive function of female cattle. This review examines how the transforming growth factor-β (TGFB) superfamily (i.e. bone morphogenetic protein (BMP) 15, growth differentiation factor (GDF) 9, anti-Müllerian hormone (AMH)) and interferon-τ (IFNT) affect ovarian function and embryo development. The oocyte in a primary follicle secretes BMP15 and GDF9, which, together, organise the surrounding granulosa and theca cells into the oocyte-cumulus-follicle complex. At the same time, the granulosa secretes AMH, which affects the oocyte. This autocrine-paracrine dialogue between the oocyte and somatic cells continues throughout follicle development and is fundamental in establishing the fertilisation potential and embryo developmental competency of oocytes. The early bovine embryo secretes IFNT, which acts at the uterine endometrium, corpus luteum and blood leucocytes. IFNT is involved in the maternal recognition of pregnancy and immunomodulation to prevent rejection of the embryo, and supports progesterone secretion. Manipulation of BMP15, GDF9, AMH and IFNT in both invivo and invitro studies has confirmed their importance in reproductive function in female cattle. This review makes the case that a deeper understanding of the biology of BMP15, GDF9, AMH and IFNT will lead to new strategies to increase embryo survival and improve fertility in cattle. The enhancement of oocyte quality, early embryo development and implantation is considered necessary for the next step change in the efficiency of natural and assisted reproduction in cattle.

The presence of an embryo affects day 14 uterine transcriptome depending on the nutritional status in sheep. b. Immune system and uterine remodeling

Transcriptomics and bioinformatics were used to investigate the potential interactions of undernutrition and the presence of the conceptus at the time of maternal recognition of pregnancy on uterine immune system and remodeling. Adult Rasa Aragonesa ewes were allocated to one of two planes of nutrition for 28 days: maintenance energy intake (control; 5 cyclic, 6 pregnant ewes) providing 7.8 MJ of metabolisable energy and 0.5 maintenance intake (undernourished; 6 cyclic, 7 pregnant ewes) providing 3.9 MJ of metabolisable energy per ewe. Uterine gene expression was measured using Agilent 15 K Sheep Microarray chip on day 14 of estrus or pregnancy. Functional bioinformatics analyses were performed using PANTHER (Protein ANalysis THrough Evolutionary Relationships) Classification System. Pregnancy affected the expression of 18 genes in both control and undernourished ewes, underscoring the relevance for embryo-maternal interactions. Immune system evidenced by classical interferon stimulated genes were activated in control and -in a lesser extent-in undernourished pregnant vs cyclic ewes. Genes involved in uterine remodeling such as protein metabolism were also upregulated with the presence of an embryo in control and undernourished ewes. However, relevant genes for the adaptation of the uterus to the embryo were differentially expressed between pregnant vs cyclic ewes both in control and undernourished groups. Undernutrition alone led to an overall weak activation of immune system pathways both in cyclic and pregnant ewes. Data revealed that cellular and immune adaptations of the uterus to pregnancy are dependent on the nutritional status.

Comparative proteome analysis reveals VPS28 regulates milk fat synthesis through ubiquitylation in bovine mammary epithelial cells

In our previous study, we found that VPS28 (vacuolar protein sorting 28 homolog) could alter ubiquitylation level to regulate milk fat synthesis in bovine primary mammary epithelial cells (BMECs). While the information on the regulation of VPS28 on proteome of milk fat synthesis is less known, we explored its effect on milk fat synthesis using isobaric tags for relative and absolute quantitation assay after knocking down VPS28 in BMECs. A total of 2,773 proteins in three biological replicates with a false discovery rate of less than 1.2% were identified and quantified. Among them, a subset of 203 proteins were screened as significantly down-(111) and up-(92) regulated in VPS28 knockdown BMECs compared with the control groups. According to Gene Ontology analysis, the differentially expressed proteins were enriched in the "proteasome," "ubiquitylation," "metabolism of fatty acids," "phosphorylation," and "ribosome." Meanwhile, some changes occurred in the morphology of BMECs and an accumulation of TG (triglyceride) and dysfunction of proteasome were identified, and a series of genes associated with milk fat synthesis, ubiquitylation and proteasome pathways were analyzed by quantitative real-time PCR. The results of this study suggested VPS28 regulated milk fat synthesis was mediated by ubiquitylation; it could be an important new area of study for milk fat synthesis and other milk fat content traits in bovine.

Changes in expression of interferon-stimulated genes and ubiquitin activating enzyme E1-like in ovine thymus during early pregnancy

As the main signal for the maternal recognition in ruminants, interferon-tau (IFNT) stimulates expression of interferon-stimulated genes (ISGs) in uterus and many extrauterine tissues. However, it is unclear that early pregnancy induces expression of signal transducer and activator of transcription 1 (STAT1), myxovirusresistance 1 (Mx1), interferon-gamma-inducible protein 10 (IP-10) and ubiquitin activating enzyme E1-like protein (UBE1L) in maternal thymus. In this study, ovine thymuses were sampled on day 16 of the estrous cycle and on days 13, 16 and 25 of gestation, and the expression of STAT1, Mx1, IP-10 and UBE1L was detected by real-time quantitative PCR, Western blot and immunohistochemistry. The results revealed that the expression of STAT1 and IP-10 reached peaks on day 16 of pregnancy, and expression of Mx1 was enhanced on day 25 of pregnancy, and STAT1 protein was located in the epithelial reticular cells, capillaries and thymic corpuscles. However, expression of UBE1L was declined during early pregnancy. In conclusion, early pregnancy influences expression of STAT1, Mx1, IP-10 and UBE1L in maternal thymus, which may participate in regulation of maternal immune tolerance during early pregnancy in sheep.

Influences of sire conception rate on pregnancy establishment in dairy cattle

Establishment of pregnancy in cattle is complex and encompasses ovulation, fertilization, blastocyst formation and growth into an elongated conceptus, pregnancy recognition signaling, and development of the embryo and placenta. The objective here was to investigate sire influences on pregnancy establishment in cattle. First, 10 Holstein bulls were classified as high or low fertility based on their sire conception rate (SCR) value. In a field trial, pregnancy at first timed insemination was not different between high and low SCR bulls. Next, 5 of the 10 sires were phenotyped using in vitro and in vivo embryo production. There was no effect of SCR classification on in vitro embryo cleavage rate, but low SCR sires produced fewer day 8 blastocysts. In superovulated heifers, high SCR bulls produced a lower percentage of unfertilized oocytes and fewer degenerated embryos compared to low SCR bulls. Recipient heifers received three to five in vivo produced embryos from either high or low SCR sires on day 7 postestrus. Day 16 conceptus recovery and length were not different between SCR groups, and the conceptus transcriptome was not appreciably different between high and low SCR sires. The reduced ability of embryos from low SCR bulls to establish pregnancy is multifactorial and encompasses sperm fertilizing ability, preimplantation embryonic development, and development of the embryo and placenta after conceptus elongation and pregnancy recognition. These studies highlight the importance of understanding genetic contributions of the sire to pregnancy establishment that is crucial to increase reproductive efficiency in dairy cattle.

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.

JAK3 and PI3K mediate bovine Interferon-tau stimulated gene expression in the blood neutrophils

Interferon tau, a 23 kDa trophoblast derived protein diffuses out from the uterus into the circulation and leads to the expression of IFNτ stimulated genes viz. ISG15 and OAS1 in blood neutrophils. The IFNτ pathway is species as well as tissue specific. To unsnarl the IFNτ downstream signaling pathway, the blood neutrophils were incubated simultaneously with 10 ng/ml of recombinant bovine interferon tau and the inhibitors of JAK2 (AG490), JAK3 (CP690550), p38 (SB202190), PI3K/Akt (LY294002), and MAPK/Erk (U0126) at specific doses for 4-hr duration. The IFNτ pathway was determined through real-time gene expression of ISG15 and OAS1; immunocytochemistry of ISG15; and Western blotting of ISG15, OAS1, pJAK3 and PI3K. The ISG15 and OAS1 expression decreased significantly (p < 0.001) in the presence of pJAK3 and PI3K inhibitors as compared to a positive control where only interferon tau was used. Immunocytochemistry revealed an attenuated ISG15 response while stimulating blood neutrophils with pJAK3 inhibitor (CP690550) and PI3K inhibitor (LY294002). Similarly, Western blot analysis of neutrophil protein fraction showed weak signals of ISG15, OAS1, pJAK3 and PI3K in the presence of pJAK3 and PI3K inhibitors. The expression profile, immunocytochemistry and western blot analysis revealed a JAK3 and PI3K mediated interferon-tau stimulated gene expression in blood neutrophils.

Npro His49 and Erns Lys412 mutations in pig bovine viral diarrhea virus type 2 synergistically enhance the cellular antiviral response

Type I interferons are major components of the innate immune response of hosts, and accordingly, many viruses have evolved mechanisms to modulate the host response during infection. Bovine viral diarrhea virus (BVDV) nonstructural protein N^pro and structural protein E^rns play important roles in inhibiting type I interferon. The aim of this study was to explore the epistatic effects of amino acid mutations in N^pro and E^rns in porcine ST cells to characterize the immune response induced by BVDV-2. Plasmids with mutant amino acids His49 (H49), Glu22 (E22) in N^pro, and His300 (H300), Lys412 (K412) in E^rns which had been changed to Alanine (A) had similar effects on type I interferon production in MDBK and ST cells, but resulted in much greater ISG15, OAS, and Mx production in ST cells. The rescued vASH/N^proH49E^rnsK412 virus showed the best efficiency with respect to modulating antiviral cytokines, indicating that the amino acids N^pro H49 and E^rns K412 had highly synergistic effects in abolishing the ability to inhibit type I interferon. These findings have importance practical implications owing to the increasing prevalence of BVDV infections, including persistent infections, in domestic pigs.