Conceptus-modulated innate immune function during early pregnancy in ruminants: a review

Abstract This review focuses on the innate immune events modulated by conceptus signaling during early pregnancy in ruminants. Interferon-tau (IFN-τ) plays a role in the recognition of pregnancy in ruminants, which involves more than the inhibition of luteolytic pulses of PGF2α to maintain corpus luteum function. For successful pregnancy establishment, the allogenic conceptus needs to prevent rejection by the female. Therefore, IFN-τ exerts paracrine and endocrine actions to regulate the innate immune system and prevent conceptus rejection. Additionally, other immune regulators work in parallel with IFN-τ, such as the pattern recognition receptors (PRR). These receptors are activated during viral and bacterial infections and in early pregnancy, but it remains unknown whether PPR expression and function are controlled by IFN-τ. Therefore, this review focuses on the main components of the innate immune response that are involved with early pregnancy and their importance to avoid conceptus rejection.

Conceptus-modulated innate immune function during early pregnancy in ruminants: a review

This review focuses on the innate immune events modulated by conceptus signaling during early pregnancy in ruminants. Interferon-tau (IFN-) plays a role in the recognition of pregnancy in ruminants, which involves more than the inhibition of luteolytic pulses of PGF2 to maintain corpus luteum function. For successful pregnancy establishment, the allogenic conceptus needs to prevent rejection by the female. Therefore, IFN- exerts paracrine and endocrine actions to regulate the innate immune system and prevent conceptus rejection. Additionally, other immune regulators work in parallel with IFN-, such as the pattern recognition receptors (PRR). These receptors are activated during viral and bacterial infections and in early pregnancy, but it remains unknown whether PPR expression and function are controlled by IFN-. Therefore, this review focuses on the main components of the innate immune response that are involved with early pregnancy and their importance to avoid conceptus rejection.(AU)

Possible impact of neutrophils on immune responses during early pregnancy in ruminants

Abstract The interaction between early embryo and maternal immune system for the establishment of pregnancy is the focus of several studies; however, it remains unclear. The maternal immune response needs to keep a balance between avoiding any damage to the conceptus and maintaining its function in combating microbes as well. When conceptus-maternal crosstalk cannot achieve this balance, pregnancy losses might occur. Intercommunication between mother and conceptus is fundamental during early pregnancy to dictate the outcome of pregnancy. In ruminants, the embryo reacts with the maternal system mainly via interferon tau (IFNT) release. IFNT can act locally on the embryo and endometrial cells and systemically in several tissues and cells to regulate their response via the expression of interferon-stimulated genes (ISGs). Also, IFNT can induce the expression of inflammatory-related genes in immune cells. Day 7 embryo induces a shift in the maternal immune response towards anti-inflammatory (Th2) immune responses. During maternal recognition of pregnancy, peripheral mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) express markers that configure an anti-inflammatory response. However, PMNs response is more sensitive to the effects of IFNT. PMNs are more likely to express interferon-stimulated genes (ISGs), transforming growth factor-beta (TGFB), interleukin 10 (IL10), and arginase-1 (ARG1), configuring one of the most rapid immune responses to early pregnancy. This review focus on the local and peripheral immune responses during early pregnancy in ruminants, mainly the PMNs function in the immune system.

Evaluation of interferon-stimulated gene 15 (ISG15) expression in blood neutrophils in beef cattle poisoned by Senecio spp

ABSTRACT: This study aimed to assess liver damage and interferon-stimulated gene 15 (ISG15) blood expression as a consequence of embryonic signaling on maternal recognition of pregnancy in beef cattle presenting natural ingestion of Senecio spp. Epidemiological aspects, as the presence of the plant, associated to gamma glutamyl transferase (GGT) activity can be used as Senecio spp. poisoning diagnosis. Maternal recognition of pregnancy period occurs when the embryo secretes interferon tau (IFNT) to signal its presence to the mother and eventually extend corpus luteum (CL) lifespan. In our study, liver damage was determined by concentration serum GGT, cytological and histopathological examinations. Reproductive status was evaluated by concentration of progesterone, CL diameter and ISG15 mRNA expression on Day 19 following fixed-time artificial insemination (FTAI). Cows were categorized into two groups based on concentration of GGT: Group 1 (GGT 30U/L) and 2 (GGT>31U/L). No difference on body condition scores was observed. All the cows presented liver damage based on cytology and histopathological exams. Cows from the Group 1 had higher pregnancy rate, presenting larger CL diameter and greater concentration of progesterone. Interestingly, ISG15 mRNA expression had no difference between Groups 1 and 2, even presenting difference in pregnancy status. These findings suggest embryonic loss beyond Day 19. It suggests late embryonic mortality may be associated to liver insufficiency. In conclusion, liver injury and/or concentration of GGT does not alter ISG15 expression on blood neutrophils, however cows presenting lower concentration of GGT ( 30U/L) had increased pregnancy status. Therefore, the concentration of GGT allow us to screen liver status and foresee a successful pregnancy in beef cattle.

RESUMO: O objetivo deste estudo foi avaliar a lesão hepática e a expressão sanguínea do gene estimulado por interferon 15 (ISG15) durante a sinalização embrionária, no reconhecimento materno da gestação, em bovinos de corte apresentando ingestão natural de Senecio spp. Fatores epidemiológicos, como a presença da planta, associados à atividade da gama glutamil transferase (GGT) podem ser utilizados como diagnóstico da intoxicação por Senecio spp. O reconhecimento materno da gestação ocorre quando o embrião secreta interferon tau (IFNT) para sinalizar sua presença à mãe. Em nosso estudo, a lesão hepática foi determinada pela concentração sérica de GGT, pelos exames citológicos e histopatológicos. O estado reprodutivo foi avaliado pela concentração de progesterona, diâmetro de corpo lúteo (CL) e expressão de mRNA ISG15 no Dia 19 após a inseminação artificial em tempo fixo (IATF). As vacas foram separadas em dois grupos com base na concentração de GGT sanguíneo: Grupo 1 (GGT 30U/L) e Grupo 2 (GGT>31U/L). Não foi observada nenhuma diferença no escore de condição corporal entre os grupos. Na citologia e nos exames histopatológicos todas as vacas apresentaram lesão hepática. As vacas do Grupo 1 apresentaram maior taxa de prenhez, maior diâmetro do CL e maior concentração de progesterona. Diferente do esperado, a expressão do mRNA ISG15 não foi diferente entre os Grupos 1 e 2, mesmo apresentando diferença na taxa de prenhez. Esses achados sugerem perda embrionária após o Ddia 19. Isso demonstra que a mortalidade embrionária tardia pode estar associada à insuficiência hepática. Dessa forma, conclui-se que a lesão hepática e/ou concentração de GGT não altera a expressão de ISG15 nos neutrófilos sanguíneos, porém vacas com menor concentração de GGT ( 30U/L) apresentaram maiores taxas de prenhez. Assim, a concentração de GGT nos permite avaliar a saúde hepática e prever uma gestação bem-sucedida em bovinos de corte.

Possible impact of neutrophils on immune responses during early pregnancy in ruminants

The interaction between early embryo and maternal immune system for the establishment of pregnancy is the focus of several studies; however, it remains unclear. The maternal immune response needs to keep a balance between avoiding any damage to the conceptus and maintaining its function in combating microbes as well. When conceptus-maternal crosstalk cannot achieve this balance, pregnancy losses might occur. Intercommunication between mother and conceptus is fundamental during early pregnancy to dictate the outcome of pregnancy. In ruminants, the embryo reacts with the maternal system mainly via interferon tau (IFNT) release. IFNT can act locally on the embryo and endometrial cells and systemically in several tissues and cells to regulate their response via the expression of interferon-stimulated genes (ISGs). Also, IFNT can induce the expression of inflammatory-related genes in immune cells. Day 7 embryo induces a shift in the maternal immune response towards anti-inflammatory (Th2) immune responses. During maternal recognition of pregnancy, peripheral mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) express markers that configure an anti-inflammatory response. However, PMNs response is more sensitive to the effects of IFNT. PMNs are more likely to express interferon-stimulated genes (ISGs), transforming growth factor-beta (TGFB), interleukin 10 (IL10), and arginase-1 (ARG1), configuring one of the most rapid immune responses to early pregnancy. This review focus on the local and peripheral immune responses during early pregnancy in ruminants, mainly the PMNs function in the immune system.(AU)

Evaluation of interferon-stimulated gene 15 (ISG15) expression in blood neutrophils in beef cattle poisoned by Senecio spp / Avaliação da expressão do gene estimulado por interferon 15 (ISG15) em neutrófilos sanguíneos em bovinos de corte intoxicados por Senecio spp

This study aimed to assess liver damage and interferon-stimulated gene 15 (ISG15) blood expression as a consequence of embryonic signaling on maternal recognition of pregnancy in beef cattle presenting natural ingestion of Senecio spp. Epidemiological aspects, as the presence of the plant, associated to gamma glutamyl transferase (GGT) activity can be used as Senecio spp. poisoning diagnosis. Maternal recognition of pregnancy period occurs when the embryo secretes interferon tau (IFNT) to signal its presence to the mother and eventually extend corpus luteum (CL) lifespan. In our study, liver damage was determined by concentration serum GGT, cytological and histopathological examinations. Reproductive status was evaluated by concentration of progesterone, CL diameter and ISG15 mRNA expression on Day 19 following fixed-time artificial insemination (FTAI). Cows were categorized into two groups based on concentration of GGT: Group 1 (GGT<30U/L) and 2 (GGT>31U/L). No difference on body condition scores was observed. All the cows presented liver damage based on cytology and histopathological exams. Cows from the Group 1 had higher pregnancy rate, presenting larger CL diameter and greater concentration of progesterone. Interestingly, ISG15 mRNA expression had no difference between Groups 1 and 2, even presenting difference in pregnancy status. These findings suggest embryonic loss beyond Day 19. It suggests late embryonic mortality may be associated to liver insufficiency. In conclusion, liver injury and/or concentration of GGT does not alter ISG15 expression on blood neutrophils, however cows presenting lower concentration of GGT (<30U/L) had increased pregnancy status. Therefore, the concentration of GGT allow us to screen liver status and foresee a successful pregnancy in beef cattle.(AU)

O objetivo deste estudo foi avaliar a lesão hepática e a expressão sanguínea do gene estimulado por interferon 15 (ISG15) durante a sinalização embrionária, no reconhecimento materno da gestação, em bovinos de corte apresentando ingestão natural de Senecio spp. Fatores epidemiológicos, como a presença da planta, associados à atividade da gama glutamil transferase (GGT) podem ser utilizados como diagnóstico da intoxicação por Senecio spp. O reconhecimento materno da gestação ocorre quando o embrião secreta interferon tau (IFNT) para sinalizar sua presença à mãe. Em nosso estudo, a lesão hepática foi determinada pela concentração sérica de GGT, pelos exames citológicos e histopatológicos. O estado reprodutivo foi avaliado pela concentração de progesterona, diâmetro de corpo lúteo (CL) e expressão de mRNA ISG15 no Dia 19 após a inseminação artificial em tempo fixo (IATF). As vacas foram separadas em dois grupos com base na concentração de GGT sanguíneo: Grupo 1 (GGT<30U/L) e Grupo 2 (GGT>31U/L). Não foi observada nenhuma diferença no escore de condição corporal entre os grupos. Na citologia e nos exames histopatológicos todas as vacas apresentaram lesão hepática. As vacas do Grupo 1 apresentaram maior taxa de prenhez, maior diâmetro do CL e maior concentração de progesterona. Diferente do esperado, a expressão do mRNA ISG15 não foi diferente entre os Grupos 1 e 2, mesmo apresentando diferença na taxa de prenhez. Esses achados sugerem perda embrionária após o Ddia 19. Isso demonstra que a mortalidade embrionária tardia pode estar associada à insuficiência hepática. Dessa forma, conclui-se que a lesão hepática e/ou concentração de GGT não altera a expressão de ISG15 nos neutrófilos sanguíneos, porém vacas com menor concentração de GGT (<30U/L) apresentaram maiores taxas de prenhez. Assim, a concentração de GGT nos permite avaliar a saúde hepática e prever uma gestação bem-sucedida em bovinos de corte.(AU)

Evaluation of interferon-stimulated gene 15 (ISG15) expression in blood neutrophils in beef cattle poisoned by Senecio spp / Avaliação da expressão do gene estimulado por interferon 15 (ISG15) em neutrófilos sanguíneos em bovinos de corte intoxicados por Senecio spp

This study aimed to assess liver damage and interferon-stimulated gene 15 (ISG15) blood expression as a consequence of embryonic signaling on maternal recognition of pregnancy in beef cattle presenting natural ingestion of Senecio spp. Epidemiological aspects, as the presence of the plant, associated to gamma glutamyl transferase (GGT) activity can be used as Senecio spp. poisoning diagnosis. Maternal recognition of pregnancy period occurs when the embryo secretes interferon tau (IFNT) to signal its presence to the mother and eventually extend corpus luteum (CL) lifespan. In our study, liver damage was determined by concentration serum GGT, cytological and histopathological examinations. Reproductive status was evaluated by concentration of progesterone, CL diameter and ISG15 mRNA expression on Day 19 following fixed-time artificial insemination (FTAI). Cows were categorized into two groups based on concentration of GGT: Group 1 (GGT<30U/L) and 2 (GGT>31U/L). No difference on body condition scores was observed. All the cows presented liver damage based on cytology and histopathological exams. Cows from the Group 1 had higher pregnancy rate, presenting larger CL diameter and greater concentration of progesterone. Interestingly, ISG15 mRNA expression had no difference between Groups 1 and 2, even presenting difference in pregnancy status. These findings suggest embryonic loss beyond Day 19. It suggests late embryonic mortality may be associated to liver insufficiency. In conclusion, liver injury and/or concentration of GGT does not alter ISG15 expression on blood neutrophils, however cows presenting lower concentration of GGT (<30U/L) had increased pregnancy status. Therefore, the concentration of GGT allow us to screen liver status and foresee a successful pregnancy in beef cattle.(AU)

O objetivo deste estudo foi avaliar a lesão hepática e a expressão sanguínea do gene estimulado por interferon 15 (ISG15) durante a sinalização embrionária, no reconhecimento materno da gestação, em bovinos de corte apresentando ingestão natural de Senecio spp. Fatores epidemiológicos, como a presença da planta, associados à atividade da gama glutamil transferase (GGT) podem ser utilizados como diagnóstico da intoxicação por Senecio spp. O reconhecimento materno da gestação ocorre quando o embrião secreta interferon tau (IFNT) para sinalizar sua presença à mãe. Em nosso estudo, a lesão hepática foi determinada pela concentração sérica de GGT, pelos exames citológicos e histopatológicos. O estado reprodutivo foi avaliado pela concentração de progesterona, diâmetro de corpo lúteo (CL) e expressão de mRNA ISG15 no Dia 19 após a inseminação artificial em tempo fixo (IATF). As vacas foram separadas em dois grupos com base na concentração de GGT sanguíneo: Grupo 1 (GGT<30U/L) e Grupo 2 (GGT>31U/L). Não foi observada nenhuma diferença no escore de condição corporal entre os grupos. Na citologia e nos exames histopatológicos todas as vacas apresentaram lesão hepática. As vacas do Grupo 1 apresentaram maior taxa de prenhez, maior diâmetro do CL e maior concentração de progesterona. Diferente do esperado, a expressão do mRNA ISG15 não foi diferente entre os Grupos 1 e 2, mesmo apresentando diferença na taxa de prenhez. Esses achados sugerem perda embrionária após o Ddia 19. Isso demonstra que a mortalidade embrionária tardia pode estar associada à insuficiência hepática. Dessa forma, conclui-se que a lesão hepática e/ou concentração de GGT não altera a expressão de ISG15 nos neutrófilos sanguíneos, porém vacas com menor concentração de GGT (<30U/L) apresentaram maiores taxas de prenhez. Assim, a concentração de GGT nos permite avaliar a saúde hepática e prever uma gestação bem-sucedida em bovinos de corte.(AU)

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.

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.(AU)

Actions of interferon tau during maternal recognition of pregnancy / Ações do interferon tau durante o reconhecimento materno da gestação

Maternal recognition of pregnancy in ruminants is a physiological process that requires an interaction between the conceptus and the mother in order to avoid luteal regression. Studies on 60s started to investigate the communication, and late on the 80s it was identified a Type I interferon called interferon tau. In the 90s the local action of interferon tau was described. It suppresses luteolytic pulses of prostaglandin F2 alpha inhibiting endometrial expression of estrogen and oxytocin receptors. Several studies presented the expression of interferonstimulated genes on extrauterine tissues. After, the endocrine action of interferon tau was described. This study revealed a greater interferon bioactivity in the serum of uterine vein from pregnant ewes when compared to nonpregnant ewes. Following a series of experiments were preformed to better understand the endocrine action of interferon tau in several extrauteine tissues. This review presents the endocrine action of interferon tau during maternal recognition of pregnancy period in ruminants.(AU)

O reconhecimento materno da gestação em ruminantes é um processo fisiológico que requer a interação entre o concepto e a mãe com o obejetivo de evitar a regressão luteal. Estudos na década de 1960 começaram a investigar essa comunicação entre concepto e mãe, e durante a década de 1980 foi identificado um tipo I de interferon que foi denominado interferon tau. Nos anos 1990, foi descrita a ação local do interferon tau. Essa ação suprime os pulsos luteolíticos de prostaglandina F2 alfa inibindo a expressão endometrial dos receptors de estrógeno e ocitocina. Muitos estudos têm apresentado a expressão dos genes estimulados por interferons nos tecidos extrauterinos. Posteriormente, a ação endócrina do interferon tau também foi descrita. Este estudo revelou uma maior bioatividade de interferon no soro da veia uterina de ovelhas prenhes quando comparada com ovelhas não gestantes. Após, uma série de experimentos foram realizados para melhor compreender a ação endócrina do interferon tau em vários tecidos extrauterinos. Esta revisão destaca a ação endócrina do interferon tau durante o período de reconhecimento materno da gestação em ruminantes.(AU)

Actions of interferon tau during maternal recognition of pregnancy / Ações do interferon tau durante o reconhecimento materno da gestação

Maternal recognition of pregnancy in ruminants is a physiological process that requires an interaction between the conceptus and the mother in order to avoid luteal regression. Studies on 60’s started to investigate the communication, and late on the 80’s it was identified a Type I interferon called interferon tau. In the 90’s the local action of interferon tau was described. It suppresses luteolytic pulses of prostaglandin F2 alpha inhibiting endometrial expression of estrogen and oxytocin receptors. Several studies presented the expression of interferonstimulated genes on extrauterine tissues. After, the endocrine action of interferon tau was described. This study revealed a greater interferon bioactivity in the serum of uterine vein from pregnant ewes when compared to nonpregnant ewes. Following a series of experiments were preformed to better understand the endocrine action of interferon tau in several extrauteine tissues. This review presents the endocrine action of interferon tau during maternal recognition of pregnancy period in ruminants.

O reconhecimento materno da gestação em ruminantes é um processo fisiológico que requer a interação entre o concepto e a mãe com o obejetivo de evitar a regressão luteal. Estudos na década de 1960 começaram a investigar essa comunicação entre concepto e mãe, e durante a década de 1980 foi identificado um tipo I de interferon que foi denominado interferon tau. Nos anos 1990, foi descrita a ação local do interferon tau. Essa ação suprime os pulsos luteolíticos de prostaglandina F2 alfa inibindo a expressão endometrial dos receptors de estrógeno e ocitocina. Muitos estudos têm apresentado a expressão dos genes estimulados por interferons nos tecidos extrauterinos. Posteriormente, a ação endócrina do interferon tau também foi descrita. Este estudo revelou uma maior bioatividade de interferon no soro da veia uterina de ovelhas prenhes quando comparada com ovelhas não gestantes. Após, uma série de experimentos foram realizados para melhor compreender a ação endócrina do interferon tau em vários tecidos extrauterinos. Esta revisão destaca a ação endócrina do interferon tau durante o período de reconhecimento materno da gestação em ruminantes.

Physiological mechanisms involved in maintaining the corpus luteum during the first two months of pregnancy

Maintenance of the corpus luteum (CL) during pregnancy is essential for continuing the elevated circulating progesterone (P4) that is required to maintain pregnancy. The mechanisms that protect the CL during early pregnancy when the non-pregnant animal would typically undergo CL regression have been extensively investigated. It is clear uterine prostaglandin F2α (PGF) causes regression of the CL in non-pregnant ruminants and that maintenance of the CL during early pregnancy is dependent upon secretion of interferon-tau (IFNT) from the elongating embryo. A number of specific mechanisms appear to be activated by IFNT. Most studies indicate that there is an inhibition of oxytocin-induced secretion of uterine PGF. There is also evidence for increased resistance to PGF action, perhaps due to secretion of PGE2 and PGE1 or direct endocrine actions of circulating IFNT. These mechanisms occur concurrently and each may help to maintain the CL during the first month of pregnancy. However, during the second month of pregnancy, IFNT is no longer secreted by the embryo. Attachment of the embryo to the uterus and subsequent placentome development have been linked to silencing of expression from the IFNT gene. In addition, there is some evidence that oxytocin responsiveness of the uterus returns during the second month of pregnancy leading to substantial basal secretion of PGF and perhaps PGF pulses. There is also no evidence that the CL during the second month of pregnancy is resistant to the actions of PGF as observed during the first month. Thus, this manuscript attempts to compare the mechanisms that maintain the CL during the first and second months of pregnancy in ruminants and provides a new, speculative, physiological model for maintenance of the CL during month two of pregnancy that is distinct from the previously-described mechanisms that maintain the CL during the first month of pregnancy.

Physiological mechanisms involved in maintaining the corpus luteum during the first two months of pregnancy

Maintenance of the corpus luteum (CL) during pregnancy is essential for continuing the elevated circulating progesterone (P4) that is required to maintain pregnancy. The mechanisms that protect the CL during early pregnancy when the non-pregnant animal would typically undergo CL regression have been extensively investigated. It is clear uterine prostaglandin F2α (PGF) causes regression of the CL in non-pregnant ruminants and that maintenance of the CL during early pregnancy is dependent upon secretion of interferon-tau (IFNT) from the elongating embryo. A number of specific mechanisms appear to be activated by IFNT. Most studies indicate that there is an inhibition of oxytocin-induced secretion of uterine PGF. There is also evidence for increased resistance to PGF action, perhaps due to secretion of PGE2 and PGE1 or direct endocrine actions of circulating IFNT. These mechanisms occur concurrently and each may help to maintain the CL during the first month of pregnancy. However, during the second month of pregnancy, IFNT is no longer secreted by the embryo. Attachment of the embryo to the uterus and subsequent placentome development have been linked to silencing of expression from the IFNT gene. In addition, there is some evidence that oxytocin responsiveness of the uterus returns during the second month of pregnancy leading to substantial basal secretion of PGF and perhaps PGF pulses. There is also no evidence that the CL during the second month of pregnancy is resistant to the actions of PGF as observed during the first month. Thus, this manuscript attempts to compare the mechanisms that maintain the CL during the first and second months of pregnancy in ruminants and provides a new, speculative, physiological model for maintenance of the CL during month two of pregnancy that is distinct from the previously-described mechanisms that maintain the CL during the first month of pregnancy.(AU)

Parthenogenetic bovine embryos secrete type I interferon capable of stimulating ISG15 in luteal cell culture

Interferon tau (IFNT) is the pregnancy recognition signal in ruminants and is secreted by trophoblast cells. Paracrine action in the endometrium is well established by inhibiting luteolytic pulses of prostaglandin F2 alpha. Recently, endocrine action was documented in the corpus luteum, blood cell and liver. It was hypothesized that conditioned medium (CM) obtained from days 7, 9 and 12 parthenogenetic embryos alters luteal cell gene expression. The aim was to establish a bovine mixed luteal cell culture to evaluate cellular response associated to interferon stimulated genes, steroidogenesis and apoptosis. Conditioned medium was obtained from Days 7, 9 and 12 parthenogenetic (PA) embryos culture. Moreover, antiviral assay was performed on CM from Days 7, 9 and 12 to verify Type I interferon activity. Luteal cell culture was validated by steroidogenic and apoptotic genes (CYP11A1, HSD3B1, BAX, BCL2, AKT and XIAP mRNA expression), and concentration of progesterone as endpoint. Luteal cell culture was treated with interferon alpha (IFNA) and CM from parthenogenetic embryos. Antiviral assay revealed Type I interferon activity on CM from embryos increasing on Days 9 and 12. ISG15 mRNA was greater in the mixed luteal cells culture treated with 1, 10 and 100ng/ml of interferon alpha (IFNA) and also on Days 7, 9 and 12 CM treatments. Concentration of progesterone was not altered in luteal cell culture regardless of treatments. Steroidogenic and apoptotic genes were similar among groups in luteal cell culture treated with different doses of IFNA or CM from PA embryos. In conclusion, parthenogenetic embryo-derived CM has antiviral activity, luteal cell culture respond to Type I interferon by expressing IGS15. These data indicate this model can be used for IFNT endocrine signaling studies.

Parthenogenetic bovine embryos secrete type I interferon capable of stimulating ISG15 in luteal cell culture

Interferon tau (IFNT) is the pregnancy recognition signal in ruminants and is secreted by trophoblast cells. Paracrine action in the endometrium is well established by inhibiting luteolytic pulses of prostaglandin F2 alpha. Recently, endocrine action was documented in the corpus luteum, blood cell and liver. It was hypothesized that conditioned medium (CM) obtained from days 7, 9 and 12 parthenogenetic embryos alters luteal cell gene expression. The aim was to establish a bovine mixed luteal cell culture to evaluate cellular response associated to interferon stimulated genes, steroidogenesis and apoptosis. Conditioned medium was obtained from Days 7, 9 and 12 parthenogenetic (PA) embryos culture. Moreover, antiviral assay was performed on CM from Days 7, 9 and 12 to verify Type I interferon activity. Luteal cell culture was validated by steroidogenic and apoptotic genes (CYP11A1, HSD3B1, BAX, BCL2, AKT and XIAP mRNA expression), and concentration of progesterone as endpoint. Luteal cell culture was treated with interferon alpha (IFNA) and CM from parthenogenetic embryos. Antiviral assay revealed Type I interferon activity on CM from embryos increasing on Days 9 and 12. ISG15 mRNA was greater in the mixed luteal cells culture treated with 1, 10 and 100ng/ml of interferon alpha (IFNA) and also on Days 7, 9 and 12 CM treatments. Concentration of progesterone was not altered in luteal cell culture regardless of treatments. Steroidogenic and apoptotic genes were similar among groups in luteal cell culture treated with different doses of IFNA or CM from PA embryos. In conclusion, parthenogenetic embryo-derived CM has antiviral activity, luteal cell culture respond to Type I interferon by expressing IGS15. These data indicate this model can be used for IFNT endocrine signaling studies.(AU)

Leptin and IGF-I improve bovine embryo quality in vitro

The in vitro embryo culture systems need further improvement to enhance the efficiency of bovine embryo production. Growth factors play key roles in embryo production and quality. The objective of this study was to define the effects of leptin, insulin-like growth factor-1 (IGF-1), and their combination on embryonic development, apoptosis, and expression profiles of a panel of developmentally important genes during 8-day embryo culture. The oocytes were aspirated from slaughterhouse ovaries of mixed breed cows. Following IVM/IVF presumptive zygotes were obtained. To accomplish this objective, presumptive zygotes (16-18 h post-insemination) were cultured in vitro as control (no supplementation, n = 349), 5 ng/ml leptin (Group I, n = 322), 100 ng/ml IGF-1 (Group II, n = 347), and 5 ng/ml leptin and 100 ng/ml IGF-1 (Group III, n = 360). All groups were supplemented with 10% fetal calf serum (FCS) on Day 4, and blastocysts were harvested on day 8. The DNA fragmented nuclei of blastocyst were determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and expression profiles of a panel of developmentally important genes were assayed by real-time polymerase chain reaction (RT-PCR). The cleavage rate and embryo development to 8-16 cell stage were higher in groups II and III as compared to control (P < 0.05), respectively. Percentage of blastocyst and mean cell numbers per blastocyst did not differ among the groups. Addition of IGF-I and/or combination with leptin decreased the number of nuclei with fragmented DNA (P < 0.01) as compared to the control group. Although the expression of glucose transporter 1 (Glut1), desmosomal glycoprotein desmocollin III (DcIII) and insulin like growth factor 2receptor (Igf2r) transcripts did not change among thegroups, interferon-tau (IF-tau) and DNAmethyltransferase 3A (Dnmt3a) were down-regulated ingroup II while heat shock protein-70 (Hsp70) and IF-tauwere up regulated in group III.[...]

Leptin and IGF-I improve bovine embryo quality in vitro

The in vitro embryo culture systems need further improvement to enhance the efficiency of bovine embryo production. Growth factors play key roles in embryo production and quality. The objective of this study was to define the effects of leptin, insulin-like growth factor-1 (IGF-1), and their combination on embryonic development, apoptosis, and expression profiles of a panel of developmentally important genes during 8-day embryo culture. The oocytes were aspirated from slaughterhouse ovaries of mixed breed cows. Following IVM/IVF presumptive zygotes were obtained. To accomplish this objective, presumptive zygotes (16-18 h post-insemination) were cultured in vitro as control (no supplementation, n = 349), 5 ng/ml leptin (Group I, n = 322), 100 ng/ml IGF-1 (Group II, n = 347), and 5 ng/ml leptin and 100 ng/ml IGF-1 (Group III, n = 360). All groups were supplemented with 10% fetal calf serum (FCS) on Day 4, and blastocysts were harvested on day 8. The DNA fragmented nuclei of blastocyst were determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and expression profiles of a panel of developmentally important genes were assayed by real-time polymerase chain reaction (RT-PCR). The cleavage rate and embryo development to 8-16 cell stage were higher in groups II and III as compared to control (P < 0.05), respectively. Percentage of blastocyst and mean cell numbers per blastocyst did not differ among the groups. Addition of IGF-I and/or combination with leptin decreased the number of nuclei with fragmented DNA (P < 0.01) as compared to the control group. Although the expression of glucose transporter 1 (Glut1), desmosomal glycoprotein desmocollin III (DcIII) and insulin like growth factor 2receptor (Igf2r) transcripts did not change among thegroups, interferon-tau (IF-tau) and DNAmethyltransferase 3A (Dnmt3a) were down-regulated ingroup II while heat shock protein-70 (Hsp70) and IF-tauwere up regulated in group III.[...](AU)

Pregnancy recognition signals in mammals: the roles of interferons and estrogens

Reproduction is a highly complex biologicalprocess requiring a dialogue between the developingconceptus (embryo-fetus and associated placentalmembranes) and maternal uterus which must beestablished during the peri-implantation period forpregnancy recognition signaling and regulation of geneexpression by uterine epithelial and stromal cells. Theuterus provide a microenvironment in which moleculessecreted by uterine epithelia or transported into theuterine lumen represent histotroph or the secretomerequired for growth and development of the conceptusand receptivity of the uterus to implantation by theconceptus. Pregnancy recognition signaling as related tosustaining the functional lifespan of the corpora lutea(CL) which produce progesterone; the hormone ofpregnancy essential for uterine functions that supportimplantation and placentation required for successfuloutcomes of pregnancy. It is within the periimplantationperiod that most embryonic deaths occur inmammals due to deficiencies attributed to uterinefunctions or failure of the conceptus to developappropriately, signal pregnancy recognition and/orundergo implantation and placentation. The endocrinestatus of the pregnant female and her nutritional status arecritical for successful establishment and maintenance ofpregnancy. The challenge is to understand the complexityof key mechanisms that are characteristic of successfulreproduction and to use that knowledge to enhancefertility and reproductive health of animals includingnonhuman primates. It is important to translateknowledge gained from studies of animals to addressissues of fertility and reproductive health in humans.

Pregnancy recognition signals in mammals: the roles of interferons and estrogens

Reproduction is a highly complex biologicalprocess requiring a dialogue between the developingconceptus (embryo-fetus and associated placentalmembranes) and maternal uterus which must beestablished during the peri-implantation period forpregnancy recognition signaling and regulation of geneexpression by uterine epithelial and stromal cells. Theuterus provide a microenvironment in which moleculessecreted by uterine epithelia or transported into theuterine lumen represent histotroph or the secretomerequired for growth and development of the conceptusand receptivity of the uterus to implantation by theconceptus. Pregnancy recognition signaling as related tosustaining the functional lifespan of the corpora lutea(CL) which produce progesterone; the hormone ofpregnancy essential for uterine functions that supportimplantation and placentation required for successfuloutcomes of pregnancy. It is within the periimplantationperiod that most embryonic deaths occur inmammals due to deficiencies attributed to uterinefunctions or failure of the conceptus to developappropriately, signal pregnancy recognition and/orundergo implantation and placentation. The endocrinestatus of the pregnant female and her nutritional status arecritical for successful establishment and maintenance ofpregnancy. The challenge is to understand the complexityof key mechanisms that are characteristic of successfulreproduction and to use that knowledge to enhancefertility and reproductive health of animals includingnonhuman primates. It is important to translateknowledge gained from studies of animals to addressissues of fertility and reproductive health in humans.(AU)

Maintenance or regression of the corpus luteum during multiple decisive periods of bovine pregnancy

In ruminants, there are specific times during the estrous cycle or pregnancy when the corpus luteum (CL) may undergo regression. This review has attempted to summarize the physiological and cellular mechanisms involved in CL regression or maintenance during four distinct periods. The first period is near day 7 when animals that are ovulating after a period of low circulating progesterone (P4), such as first pubertal ovulation or first postpartum ovulation, are at risk of having a premature increase in Prostaglandin F2α (PGF) secreted from the uterus resulting in early CL regression and a short estrous cycle. The second period is when normal luteolysis occurs at day 18-25 of the cycle or when the CL is rescued by interferon-tau secreted by the elongating embryo. The uterine mechanisms that determine the timing of this luteolysis or the prevention of luteolysis have been generally defined. Induction and activation of endometrial E2 receptors result in induction of endometrial oxytocin receptors that can now be activated by normal pulses of oxytocin. Of particular importance is the observation that the primary mechanisms are only activated through local (ipsilateral) and not a systemic route due to transfer of PGF from the uterine vein to the ovarian artery. In addition at the CL level, studies are providing definition to the cellular and molecular mechanisms that are activated in response to uterine PGF pulses or pregnancy