Macrosomia Associated With Maternal Serum Insulin-Like Growth Factor-I and -II in Diabetic Pregnancy:

Fetal growth regulation via insulin-like growth factor axis in normal and diabetic pregnancy

OBJECTIVES

Diabetes mellitus (DM) in pregnancy and gestational diabetes remain a considerable cause of pregnancy complications, and fetal macrosomia is among them. Insulin, insulin-like growth factors (IGFs), and components of their signal-transduction axes belong to the predominant growth regulators and are implicated in glucose homeostasis. This study aimed to evaluate the available evidence on the association between the IGF axis and fetal anthropometric parameters in human diabetic pregnancy.

METHODS

PubMed, Medline, Web of Science, and CNKI databases (1981-2021) were searched.

RESULTS

Maternal and cord serum IGF-I levels are suggested to be positively associated with weight and length of neonates born to mothers with type 1 DM. The results concerning IGF-II and IGFBPs in type 1 DM or any of the IGF axis components in type 2 DM remain controversial. The alterations of maternal serum IGFs concentrations throughout diabetic and non-diabetic pregnancy do not appear to be the same. Maternal 1st trimester IGF-I level is positively associated with fetal birth weight in DM.

CONCLUSIONS

Research on the IGF axis should take gestational age of sampling, presence of DM, and insulin administration into account. Maternal 1st trimester IGF-I level might become a predictor for macrosomia development in diabetic pregnancy.

MT1-MMP expression in first-trimester placental tissue is upregulated in type 1 diabetes as a result of elevated insulin and tumor necrosis factor-alpha levels

OBJECTIVE

In pregestational diabetes, the placenta at term of gestation is characterized by various structural and functional changes. Whether similar alterations occur in the first trimester has remained elusive. Placental development requires proper trophoblast invasion and tissue remodeling, processes involving matrix metalloproteinases (MMPs) of which the membrane-anchored members (MT-MMPs) such as MT1-MMPs are key players. Here, we hypothesize a dysregulation of placental MT1-MMP in the first trimester of type 1 diabetic pregnancies induced by the diabetic environment.

RESEARCH DESIGN AND METHODS

MT1-MMP protein was measured in first-trimester placentas of healthy (n = 13) and type 1 diabetic (n = 13) women. To identify potential regulators, first-trimester trophoblasts were cultured under hyperglycemia and various insulin, IGF-I, IGF-II, and tumor necrosis factor-alpha (TNF-alpha) concentrations in presence or absence of signaling pathway inhibitors.

RESULTS

MT1-MMP was strongly expressed in first-trimester trophoblasts. In type 1 diabetes, placental pro-MT1-MMP was upregulated, whereas active MT1-MMP expression was only increased in late first trimester. In isolated primary trophoblasts, insulin, IGF-I, IGF-II, and TNF-alpha upregulated MT1-MMP expression, whereas glucose had no effect. The insulin effect was dependent on phosphatidylinositol 3-kinase, the IGF-I effect on mitogen-activated protein kinase, and the IGF-II effect on both.

CONCLUSIONS

This is the first study reporting alterations in the first-trimester placenta in type 1 diabetes. The upregulated MT1-MMP expression in type 1 diabetes may be the result of higher maternal insulin and TNF-alpha levels. We speculate that the elevated MT1-MMP will affect placental development and may thus contribute to long-term structural alterations in the placenta in pregestational diabetes.

Errata

Intrauterine growth restriction (IUGR) represents an important risk factor for perinatal complications and for adult disease. IUGR is associated with a down‐regulation of placental amino acid transporters; however, whether these changes are primary events directly contributing to IUGR or a secondary consequence is unknown. We investigated the time course of changes in placental and fetal growth, placental nutrient transport in vivo and the expression of placental nutrient transporters in pregnant rats subjected to protein malnutrition, a model for IUGR. Pregnant rats were given either a low protein (LP) diet (n= 64) or an isocaloric control diet (n= 66) throughout pregnancy. Maternal insulin, leptin and IGF‐I levels decreased, whereas maternal amino acid concentrations increased moderately in response to the LP diet. Fetal and placental weights in the LP group were unaltered compared to control diet at gestational day (GD) 15, 18 and 19 but significantly reduced at GD 21. Placental system A transport activity was reduced at GD 19 and 21 in response to a low protein diet. Placental protein expression of SNAT2 was decreased at GD 21. In conclusion, placental amino acid transport is down‐regulated prior to the development of IUGR, suggesting that these placental transport changes are a cause, rather than a consequence, of IUGR. Reduced maternal levels of insulin, leptin and IGF‐1 may link maternal protein malnutrition to reduced fetal growth by down‐regulation of key placental amino acid transporters.

Increased serum IGF-I during pregnancy is associated with progression of diabetic retinopathy

The IGF system has been associated with development and progression of diabetic retinopathy. We examined whether a simple measurement of the IGF system (serum total IGF-I) correlated with progression of diabetic retinopathy in pregnancy in type 1 diabetes. A prospective observational study was performed in 103 pregnant women with type 1 diabetes. Serum IGF-I was measured in maternal serum from week 14, every fourth week until week 30, and every second week until delivery. Twenty-four-hour blood pressure was measured with a portable oscillometry monitor. The women had visual acuity testing and fundus photography before pregnancy, once in each trimester, and 4 months after birth. Each eye was assigned an overall retinopathy grade on a scale from 1 to 6 independently by two experienced graders. During pregnancy, serum IGF-I increased with increasing gestational age until a plateau was reached in week 32. Progression of retinopathy was significantly associated with a higher level of IGF-I (P < 0.01). Serum IGF-I increased with increasing progression of retinopathy. Change of retinopathy was significantly associated with level of IGF-I (P < 0.01). During pregnancy, serum IGF-I increased with increasing birth weight until a plateau was reached in week 32. Birth weight was significantly associated with a higher level of serum IGF-I (P < 0.01).