Week 3 Flashcards
What are the changes in the inflammatory state of the woman throughout the pregnancy? Why?
First Trimester: Pro-inflammatory state; promote implantation
Second Trimester: Anti-inflammatory state; fetal growth
Third Trimester: Pro-inflammatory; promote labor
Describe the inflammatory state in the first trimester of pregnancy and how specific immune cells work throughout this period of pregnancy?
During the first trimester of pregnancy, there is a pro-inflammatory state. The blastocyst needs to attach to the endometrial wall of the placenta for the fetus to be fully implanted in the placenta. In order for that to happen, dendritic cells secrete factors that remove the mucin layer which normally covers the endometrial wall of the placenta to uncover the molecules to which the blastocyst will bind to. Dendritic cells will also secrete signals which increase the likelihood of implantation. Lastly, immune infiltrates (macrophages, NK cells) will also rush to the site of implantation to promote tolerance of the fetus.
What are Th1 cells? What do they do? When are they released in the context of pregnancy?
Th1 cells are a subdivision of CD4 T-helper cells which produce pro-inflammatory cytokines. They’re released in the first and third trimesters of pregnancy.
What are Th2 cells? What do they do? When are they released in the context of pregnancy?
Th2 cells are a subdivision of CD4 T-helper cells which produce anti-inflammatory cytokines. They are not released in pregnancy, although the second trimester of pregnancy is said to move toward a Th2 environment because of the suppression of Th1 cells.
What are T-reg cells? What do they do? When are they released in the context of pregnancy?
T-reg cells are a subdivision of CD4 T-helper cells which produce anti-inflammatory action and promote immune tolerance. They also suppress the action of Th1 cells. They are released in the second trimester of pregnancy.
What type of T helper cell would you expect to see released during infection which could be detrimental to pregnancy?
Th1 cells
Describe the necessary actions of the following cells during the second trimester of pregnancy and describe their importance in the development of the pregnancy. Macrophages, T-reg, NK?
Macrophages: Release anti-inflammatory cytokines to move toward a Th2 environment, and phagocytose any dying cells of trophoblast. This is crucial as it prevents the release paternal antigens which would trigger maternal immune response against the fetus
T-reg: Protect fetus against rejection by promoting immune tolerance, as well as maintain anti-inflammatory (Th2) environment
NK: Recognize non-self-antigens, induce T-reg cells, and interact with macrophages.
What would be the result of a switch from a Th2 to a Th1 environment during the second trimester of pregnancy?
It could result in miscarriage or preterm birth.
Describe the pro-inflammatory state required during the third trimester of pregnancy? Why is it necessary?
The pro-inflammatory state during the third trimester of pregnancy is necessary to allow labour to occur. The influx of immune cells into the muscular wall of the uterus promotes contractions and separations of the placenta.
What are some (non T-helper cell) immune changes that occur during pregnancy?
There is a relative decrease in the concentrations of B cells because of pregnancy hormones. There is also a decrease of antibody levels due to hemodilution.
What is the effect of women’s adapted immune system during pregnancy when catching influenza?
While pregnant women are not at an increased risk of infection, they are at risk for more severe disease in the late pregnancy compared to non-pregnant women. More likely to be caused due to anatomical and physiological changes rather than altered immune response.
What are the fetal consequences of catching maternal influenza?
- Preterm delivery
- Stillbirth
- Small for gestational age
What is a way to increase prevention from maternal influenza?
Influenza vaccine once pregnant.
List infections which are associated with being more severe in pregnant women? Why?
Listeria: Higher risk of disseminated disease, associated with miscarriage and stillbirth. Placenta is thought to act as a reservoir allowing uncontrolled spread
Hepatitis E: Higher incidence, increased rates of fulminant hepatitis and death. Possibly due to the increased replication of the virus due to estradiol
Malaria: Higher incidence of severe malaria, possibly due to trophism of parasites for placental tissue.
What is the reason behind women being more prone to catching certain disease/developing worst effects of the disease while pregnant?
Two reasons: Adapted immune system throughout pregnancy (not immunosuppression) as well as physiological and anatomical changes of pregnancy.
Describe the process of maternal-fetal IgG transfer?
The placenta has a layer of specialized cells called syncytotrophoblasts. Maternal IgGs pass through this layer through active transfer into the stroma of the placenta using specialized receptors called FcRn. From the stroma, they are then taken up into the fetal endothelium.
What is the proportion of fetal IgGs as a proportion of the mother’s at birth?
Oftentimes the baby’s IgG concentrations are higher than the mother’s (>100%) due to the maternal-fetal IgG transfer during gestation.
Why is the transfer of IgGs from the mother to the fetus so important?
It provides the baby with protection from certain diseases during the first few months of life while as it creates its own IgGs.
Why was there a period in which pertussis was occurring at very high rates in infants between 2011 and 2012? What did they do to solve that?
Whooping cough was endemic in the infant population between 2011 and 2012 due to many of the mothers having had vaccination for it in their own childhood. Over time, their own IgG concentrations against pertussis faded, which as a result, meant that their own babies were receiving very low, if any IgGs against pertussis through maternal IgG transfer. This left them at risk of catching it in the first weeks of life.
In order to fight this phenomenon, pertussis vaccination in pregnancy started becoming recommended in 2012 in order to get an immune response which creates IgGs against pertussis, and by association, protect the baby through maternal IgG transfer.
How many week is human gestation?
38 weeks from conception
What are the main relaxant and stimulatory hormones of the uterus?
Progesterone is the main relaxant while estrogen is the main stimulatory hormone
During pregnancy, what hormone is mostly dominating the uterus?
Progesterone – keeps the uterus in a relaxed state
How does progesterone act as a relaxant during pregnancy?
Progesterone hyperpolarizes myometrial cells, making them unable to contract, as well as inhibiting prostaglandin synthesis.
How does the hormonal profile of the uterus shift from during pregnancy to during labor?
During pregnancy, the hormones dominating the uterus are relaxant hormones – notably progesterone. During labor however, there is a large shift which causes estrogen to rise and progesterone to be lowered.
