Regulation of uterine function by cytokines in cows: Possible actions of tumor necrosis factor-alpha, interleukin-1alpha and interferon-tau

Effects of milk osteopontin on the endometrial epidermal growth factor profile and restoration of fertility in repeat breeder dairy cows

Endometrial epidermal growth factor (EGF) shows a cyclic change with two peaks on Days 2-4 and 13-14 during the estrous cycle. An altered (i.e., loss of the two peaks) profile has been linked to reduced fertility in repeat breeder cows. We previously demonstrated that a form of osteopontin (OPN), with a molecular weight of 29 kDa and found in bull seminal plasma (SP), normalized the EGF profile and restored fertility in repeat breeder cows. OPN has many molecular forms due to post-translational modifications and is abundant in bovine milk. The purpose of the present study was to investigate whether mOPN normalizes the endometrial EGF profile and restores fertility in repeat breeder dairy cows with an altered EGF profile. OPN was separated by one-step anion-exchange column chromatography from the whey of bovine milk. Purified mOPN was verified by Western blotting and peptide mass fingerprinting analyses. The OPN fraction showed three major protein bands of 61, 37 and 31 kDa (peptides I, II, and III, respectively) on SDS-PAGE. All three major bands were identified as OPNs by Western blotting and their tryptic peptide masses were matched at approximately 50, 40, and 10%, respectively, to the bovine OPN amino acid sequence by a peptide mass finger printing analysis. The three bands accounted for approximately 85% of the total protein content and 6-23 mg of OPN was obtained from 1 L of bovine milk. A lyophilized eluate containing 1.3 mg of mOPN (171 cows), 0.5 mL of frozen SP (62 cows), and PBS (84 cows) was infused at estrus into the vagina of repeat breeder cows with an altered EGF profile. Some of the cows treated with mOPN, SP, and PBS (46, 50, and 45 cows, respectively) were inseminated immediately before the infusion and then examined for pregnancy between Days 60 and 65. The rate at which mOPN to normalize the EGF profile (56.1%) was similar to that of SP (58.1%) and higher than that of PBS (23.8%) (P < 0.05). The conception rate after the infusion of mOPN (43.5%) was similar to that of SP (40.0%) and higher than that of PBS (22.2%) (P < 0.05). The present results indicate that the infusion of mOPN into the vagina is a treatment option for repeat breeder cows with an altered EGF profile. Further studies are needed to compare the capacity of the three OPN molecules in milk to normalize the EGF profile, together with their molecular characteristics due to post-translational modifications.

Expression of hypoxia-inducible factors and vascular endothelial growth factor during pregnancy in the feline uterus

Hypoxia-inducible factors (HIFs) and vascular endothelial growth factor (VEGF) have critical roles during the development of the fetomaternal unit. The HIFs regulate placentation and vascularization by stimulation of VEGF gene expression. This study aimed to investigate the expression profiles of HIF gene family and VEGF in the cat uterus during pregnancy. Tissue samples of the whole uterine wall were collected after ovariohysterectomy and allocated to the following groups: embryo positive (group 1 [G1], n = 7, 7 days after mating), early pregnancy (group 2 [G2], n = 7, 20 days after mating), mid-pregnancy (group 3 [G3], n = 7, 24 days after mating), late pregnancy (group 4 [G4], n = 7, 30-45 days after mating), and oocyte positive groups (group 5 [G5], n = 7, 7 days after induction of ovulation with GnRH analog). Relative mRNA levels were determined by real-time polymerase chain reaction. As housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase was used. The relative gene expression of HIF1A in G5 was found to be significantly higher than that of other groups (G1, G2, G3, and G4) (P < 0.05). In addition, the expression of HIF2A in G5 was higher than that of G1 and HIF2A gene expression at placentation sites of G4 was higher than in G1, G2, and G3 (P < 0.05). Immunohistochemistry indicated that HIF1A, HIF2A, and VEGF expressions were observed in different cell types of uterine and placental tissues in late pregnancy and oocyte groups. The expression of HIF3A did not change significantly in any group investigated. These observations suggest that HIFs and VEGF may play a role in the establishment and development of pregnancy.

Evaluating the interaction between progesterone, tumor necrosis factor-alpha and cortisol on early loss of transferred embryo in beef cows

Mason, M., Cuadra, E. J., Elsasser, T. H., Lopez, J. and Yoonsung, J. 2013. Evaluating the interaction between progesterone, tumor necrosis factor-alpha and cortisol on early loss of transferred embryo in beef cows. Can. J. Anim. Sci. 93: 217–225. Fifty-eight non-lactating cows previously synchronized for estrus were assigned to two treatments to assess the effects of progesterone supplementation and its correlation with tumor necrosis factor-α (TNF-α) and cortisol on the survival of the transferred embryos. On day 7 after exhibiting estrus (day 0), cows in both groups received embryos. In contrast with the control group, animals in the CIDR-group had a controlled internal drug release (CIDR) additionally inserted. Blood samples for progesterone, TNF-α and cortisol analysis were taken immediately before insertion and removal of CIDRs and 7 d after insertion. Progesterone did not differ between the control and the CIDR animals at any day of the study; however, it significantly increased at 7 and 14 d after insertion of the embryos in the control animals, compared with the levels observed in that same experimental group at the time of the transfer. Regardless of the treatment, all pregnant cows experienced a significant increase in progesterone from day 0 to day 7. Progesterone on day 0 was correlated to itself (r=0.46) on day 14 and to TNF-α (r=−0.37) on day 0 in pregnant animals; TNF-α on day 7 was significantly higher in pregnant cows compared with non-pregnant and correlated between day 0 and day 14. These results suggest that high levels of progesterone during the first 14 d after the transfer are indicative of the survival of transferred embryos. Additionally, these data also indicate that the decrease in TNF-α concentration on day 7 after the transfer of embryos may be associated with the low concentrations of progesterone observed in the non-pregnant animals.

Comparison of expression levels of candidate genes in endometrium of dairy heifers and lactating dairy cows

Pretheeban, T., Gordon, M. B., Singh, R. and Rajamahendran, R. 2011. Comparison of expression levels of candidate genes in endometrium of dairy heifers and lactating dairy cows. Can. J. Anim. Sci. 91: 255–264. Pregnancy rates (PR) in high-producing lactating dairy cows have declined drastically over the past several decades, but those of heifers have remained constant. Reduced PR could be due to multiple causes, and the underlying pathophysiological mechanisms are still unclear. A compromised maternal uterine environment could be one of factors that could affect the PR. This study was performed to compare the nature of the uterine environment in dairy heifers and lactating dairy cows (2nd/3rd parity) by analyzing the expression levels of selected endometrial genes. Estrus was synchronized in heifers (n=5) and lactating dairy cows (n=5) and endometrial biopsies were performed during the mid luteal phase (day 11) of the estrous cycle. Real-time polymerase chain reaction (Q-RT PCR) and immunohistochemistry were performed to analyse the mRNA and protein levels of genes respectively. Relative abundance of BCL2, HSPA1A, IL1A, TNF, IGF1, FGF2 and SERPINA14 transcripts and the protein expression of IL1A, TNF and FGF2 were significantly higher in heifers in comparison with lactating dairy cows. Our findings suggest an altered endometrial environment in lactating dairy cows compared with heifers. However, whether these differences play a role in pregnancy outcomes should be further investigated.

Expressions of Estrogen Receptors in the Bovine Corpus Luteum: Cyclic Changes and Effects of Prostaglandin F2.ALPHA. and Cytokines

Estrogen (E) exerts its function by binding to two intracellular estrogen receptors, ERalpha and ERbeta. Although ERs have been reported to be expressed in the bovine corpus luteum (CL), the mechanisms that control ER expression in the bovine CL are not fully understood. To determine the possible regulatory mechanisms of ERalpha and ERbeta that meditate distinct E functions, we examined 1) the changes in the protein expressions of ERs in the CL throughout the luteal phase and 2) the effects of prostaglandin (PG) F2alpha, tumor necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) on the expressions of ERs in cultured bovine luteal cells. Western blot analyses revealed that ERalpha and ERbeta proteins were expressed throughout the luteal phase. The ERalpha protein level was high at the early luteal (Days 2-3 after ovulation) and mid-luteal stages (Days 8-12) and was extremely low at the regressed luteal stage (Days 19-21). The ERbeta protein level increased from the early to developing luteal stage, remained at the same level at the mid-luteal stage and decreased thereafter. The ratio of ERbeta to ERalpha was higher in the regressed stage than in the other stages. Luteal cells obtained from mid-stage CLs (Days 8-12) were incubated with PGF2alpha (0.01-1 microM), TNFalpha (0.0145-1.45 nM) or IFNgamma (0.0125-1.25 nM) for 24 h. PGF2alpha and TNFalpha inhibited ERa and ERbeta mRNA expressions. IFNgamma suppressed ERbeta mRNA expression but did not affect the expression of ERalpha mRNA. However, the ERalpha and ERbeta protein levels were not affected by any of the above treatments. These data indicate that PGF2alpha, TNFalpha and IFNgamma regulate ERalpha and ERbeta mRNA expressions in bovine luteal cells. Moreover, the changes in the ERbeta/ERalpha ratio throughout the luteal phase suggest that ERalpha is associated with luteal maintenance. Therefore, a dramatic decrease in ERalpha at the regressed luteal stage could result in progression of structural luteolysis in the bovine CL.