Advertisement
Browse Subject Areas
?

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Open Access

Peer-reviewed

Research Article

Effects of Cord Serum Insulin, IGF-II, IGFBP-2, IL-6 and Cortisol Concentrations on Human Birth Weight and Length: Pilot Study

Abstract

Background

The IGF system is recognised to be important for fetal growth. We previously described increased Insulin-like growth factor binding protein (IGFBP)-2 cord serum concentrations in intra-uterine growth retardation (IUGR) compared with appropriate for gestational age (AGA) newborns, and a positive relationship of IGFBP-2 with Interleukin (IL)-6. The role of cortisol in the fetus at birth is largely unknown, and interactions among peptides are their real effect on birth size is unknown. Furthermore, almost all studies have previously assayed peptides in serum several years after birth, and follow-up data from pregnancy are always lacking. This study aimed at establishing and clarifying the effect of cord serum insulin, IGF-II, IGFBP-2, cortisol and IL-6 concentrations on birth length and weight.

Methods

23 IUGR and 37 AGA subjects were followed up from the beginning of pregnancy, and were of comparable gestational age. Insulin, IGF-II, IGFBP-2, cortisol and IL-6 concentrations were assayed in cord serum at birth, and a multiple regression model was designed and applied to assess which were the significant biochemical determinants of birth size.

Results

Insulin, cortisol, and IL-6, showed similar concentrations in IUGR and AGA as previously described, whereas IGF-II was lower, and IGFBP-2 increased in IUGR compared with AGA. IGF-II serum concentration was found to have a significant positive effect on both birth length (r::0.546; p: 0.001) and weight (r:0.679; p: 0.0001). IGFBP-2 had a near significant negative effect on both birth weight (r:−0.342; p: 0.05) and length (r:−0.372; p:0.03).

Conclusion

IGF-II cord serum concentration was shown to have a significant positive effect on both birth length and weight, whereas IGFBP-2 had a significant negative effect. Insulin, cortisol, and IL-6 cord serum concentrations had no significant effect on birth size.

Citation: Smerieri A, Petraroli M, Ziveri MA, Volta C, Bernasconi S, Street ME (2011) Effects of Cord Serum Insulin, IGF-II, IGFBP-2, IL-6 and Cortisol Concentrations on Human Birth Weight and Length: Pilot Study. PLoS ONE 6(12): e29562. https://doi.org/10.1371/journal.pone.0029562

Editor: Guoying Wang, John Hopkins Bloomberg School of Public Health, United States of America

Received: July 14, 2011; Accepted: November 30, 2011; Published: December 29, 2011

Copyright: © 2011 Smerieri et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Funding: Grant support for this study was from the Department of Paediatrics, University of Parma, Italy. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Fetal growth is driven mainly by the IGF system as experiments in knockout mice have shown [1], [2]. IGF-II and the type I IGF receptor are thought to be the most important for fetal growth [3], [4].

We described increased IGFBP-2 cord serum concentrations in IUGR compared with appropriate for gestational age (AGA) newborns, and a positive relationship of serum IL-6 with IGFBP-2 [5], although IL-6 concentration did not show any changes in the two conditions. We described instead increased IL-6 mRNA and protein concentrations in placental lysates from IUGR [5], and our recent evidence suggested a negative effect, although not a major effect, of IL-6 placental concentration on birth size (our unpublished data).

Very little data has been published on the fetus to date. Certainly it is of interest to consider the described molecular mechanisms by which IL-6 can induce insulin-resistance [6], [7].

Furthermore, animal and human studies showed a marked activation of the hypothalamic-pituitary-adrenal axis by IL-6 infusion [8]–[10].

We previously described similar cortisol and insulin concentrations in cord serum of newborns, both IUGR, and AGA.

The role of cortisol in the fetus at birth is largely unknown. Interestingly, Cianfarani et al. reported a positive correlation of cortisol serum concentrations with IGFBP-1, and a negative correlation with IGF-I and length gain in the first 3 months of life, in normal neonates [11]. The same authors subsequently reported higher cortisol serum concentrations at the age of nine years in IUGR subjects who failed to catch-up with growth, compared with those who caught-up, and a negative relationship with birth weight. It was also suggested that the increased cortisol serum concentrations reduced IGFBP-3 proteolysis reducing IGF bioavailability [12].

IUGR and appropriate for gestational age (AGA) newborns show differences but are subjected overall to the same biological laws.

We followed-up a unique series of newborns, both IUGR and AGA, from pregnancy to birth [5], [6], and assessed in cord serum which peptides had a significant effect on birth length and weight, among insulin, IGF-II, IGFBP-2, cortisol and IL-6.

Materials and Methods

Subjects

Twenty-three IUGR (13M, 10F) and 37 AGA (18M, 19F), births of comparable gestational age (34.8±0.6 vs. 36.1±0.4 weeks, respectively, n.s.) were followed during pregnancy. All pregnancies were dated correctly by ultrasound during the first trimester of gestation.

AGA newborns were defined on the basis of a normal birth weight (<80th and >10th centiles) with respect to the Italian standards [13], a normal pregnancy and the absence of maternal risk factors.

The diagnosis of IUGR was made within the 32nd week of gestation and was ascribed to a probable placental cause after excluding other causes as infections, chromosomal abnormalities, genetic syndromes, maternal malnutrition, substance abuse including smoking, gross placental abnormalities and multiple fetuses. No cases with hypertension, gestational diabetes or reduced amount of amniotic fluid were included in the study. Mothers were all normal-weight subjects and data on parity, were collected also.

The IUGR pregnancies were diagnosed by ultrasound according to the following criteria: abdominal circumference <10th centile and/or shift of fetal growth with a reduction of abdominal circumference with respect to the measure taken during the 20th week of gestation. In IUGR subjects, doppler velocimetry was altered in almost all cases in the placenta and/or fetus site. All neonates, both IUGR and controls, were delivered by elective caesarean section (CS).

The causes of preterm birth (<38 weeks of gestation) in the AGA newborns were: intra-hepatic cholestasis in a woman who had underwent a previous CS, premature rupture of membranes with breech presentation and delivery within 4 hours with no signs of infection. Elective CS in these subjects was performed because of refusal of vaginal delivery for psychological reasons, or because of a previous CS.

We could obtain a complete data-set on which this study was performed in 34 subjects. The main clinical features of these newborns are shown in Table 1.

thumbnail
Download:
Table 1. Main clinical features at birth of both IUGR and AGA newborns.

https://doi.org/10.1371/journal.pone.0029562.t001

Data collection and measuring techniques

Length (Lt) and weight (Wt) at birth was measured by trained midwives at our hospital using exact measuring equipment for length measurements. At birth auxological data were plotted according on to the Italian standards [13].

At birth the following information was also collected: age of the mother, weight at birth of both parents, body mass index (BMI) of the mother before pregnancy, previous gynaecological history, medical history during pregnancy, fetal biophysical data (exact duration of pregnancy, growth trend), clinical data at delivery (indication for CS, neonatal data as sex, weight, length, head circumference, APGAR score, acid-base equilibrium, perinatal data), weight and macroscopic aspect of the placenta.

Collection of biological material

Umbilical cord serum from IUGR and AGA births were collected at birth and treated as previously described [5]. The blood was delivered to the laboratory within 20 minutes, centrifuged (2000 g/min for 10 minutes at 4°C) and the sera aliquoted and stored at −80°C until assayed.

Cord serum assays

Peptides were assayed as previously described, prior to this study [5], [6].

Briefly, IGF-II was measured using an IRMA method (Diagnostic System Laboratories, Inc. Webster, Texas, USA).

IGFBP-2 was assayed using a RIA method (Diagnostic System Laboratories, Inc. Webster, Texas, USA).

Insulin was assayed using a specific IRMA assay (DiaSorin S.p.A., Saluggia, Italy).

IL-6 was measured using an ultrasensitive ELISA method (Quantikine HS, R&D Systems, Minneapolis, MN, USA).

Cortisol was assayed using a specific RIA assay (DiaSorin S.p.A., Saluggia, Italy).

Ethical approval

Informed consent was obtained from the mothers. The study was approved by the Ethics Committee of the University of Parma Medical School.

Statistical analysis

Statistical analysis was performed using SPSS 18.0 for Windows (SPSS, Inc, Chicago, IL).

A complete data-set with both growth parameters at birth, and all peptide concentrations in placenta could be obtained for 34 subjects.

Results for males and females were combined as in this series we did not detect any significant difference between the two sexes.

Prior to the study we compared concentrations between cord serum peptide concentrations to check whether previous reported differences were confirmed in this population using an unpaired T test. Results are reported in Table 2, and confirmed our previous findings [5], [6].

thumbnail
Download:
Table 2. Concentrations of cord serum peptides in IUGR and AGA at birth.

https://doi.org/10.1371/journal.pone.0029562.t002

The normal distribution of the data was determined using the Kolmogorov-Smirnov test.

Multiple linear regression analysis was used, with stepwise eliminations of the independent variables, to study the effect of individual peptides on parameters of birth size of both IUGR and AGA newborns, as both populations are subjected to the same general growth rules, and to obtain acceptable statistical power. No significant effect of gestational age was found as expected, considering that gestational ages were similar.

Parity was ruled out also as was similar in the two groups.

We used Bonferroni correction to correct for multiple linear regression modeling. Statistical significance was set at a p-value less than 0.007 (p: 0.05/x; x = 7).

For the analysis of the variables influencing both length and weight at birth, the independent variables were insulin, IGF-II, IGFBP-2, cortisol, and IL-6 concentrations in cord serum at birth.

Results

Determinants of birth length

In the multiple regression model the overall R2 was 0.570 (p:0.0001).

IGF-II cord serum concentration was shown to have a significant positive effect on birth length (p: 0.001) (Table 3).

thumbnail
Download:
Table 3. Effect of cord serum insulin, IGF-II, IGFBP-2, cortisol, and IL-6 on birth length.

https://doi.org/10.1371/journal.pone.0029562.t003

IGFBP-2 cord serum concentration had a negative effect on birth length (p:0.03) (Table 3).

No significant effect of insulin, cortisol, and IL-6 was shown.

Determinants of birth weight

In the multiple regression model the overall R2 was 0.461 (p:0.0001).

IGF-II cord serum concentration was shown to have a significant positive effect on birth weight ( p: 0.0001) (Table 4).

thumbnail
Download:
Table 4. Effect of cord serum insulin, IGF-II, IGFBP-2, cortisol, and IL-6 on birth weight.

https://doi.org/10.1371/journal.pone.0029562.t004

IGFBP-2 cord serum concentration had a negative effect on birth weight (p:0.05) (Table 4).

Discussion

Among the cord serum peptides analysed, we described IGF-II and IGFBP-2 as the peptides having the most important effect on both birth length and weight. In this pilot study, insulin, cortisol, and IL-6 cord serum concentrations did not seem to have a major effect on birth size.

Data in the Literature to date, concerning the relationship of IGF-II with fetal growth are still controversial [14]–[18]. Our IGF-II finding is in accordance with the experimental evidence in animal models, in particular, in mouse models [3], [19]–[20]. Recent data have further proven, from a genetic point of view, the growth-promoting function of IGF-II during mouse embryogenesis, which has been shown to be mediated in part by signalling through the insulin receptor [19].

Interestingly, IGF-II has been shown to have also a critical role for neural and cardiovascular development in zebrafish embryos [21], and in general distinct functions have been proven during organogenesis, including the embryonic development of the kidneys [22].

Our finding is in agreement with previous studies also, in humans, showing that IGF-II gene polymorphisms are associated with birth weight and fetal growth, as some gene polymorphisms through IGF-II gene expression clearly associate with birth weight SDS [23], [24]. However, there are few and controversial data on the correspondence of gene polymorphisms and IGF-II serum concentrations [24]. Finally, studies have shown that IGF-II is also capable of stimulating somatic overgrowth in utero [25].

We previously described increased IGFBP-2 cord serum concentrations in IUGR compared with AGA newborns, however, the biological meaning of that finding with respect to other changes detected in serum in IUGR at that time was unknown, as well as clear relationships with birth length and/or weight [5].

This pilot study now suggests a major negative effect of IGFBP-2 on both birth length and weight, altogether a novel and interesting finding, in particular, in the light of recent publications. IGFBP-2 has been found in fact to be possibly the most useful, among other peptides of the IGF system, in assessing nutritional status in preterm neonates during the early postnatal period [26], and in adults a strong association between low IGFBP-2 levels and metabolic syndrome has been identified [27]. A recent study has further shown that during clamp studies, insulin increases IGFBP-2, and that IGFBP-2 was an independent predictor of insulin sensitivity. This suggested that this peptide played an important role in the insulin-IGF cross talk and was thus closely linked to insulin resistance [28]. Moreover, in obesity, IGFBP-2 was shown recently to reflect long-term insulin sensitivity [29].

Interestingly, in recent years independent effects of IGFBP-2 on glucose metabolism have been discovered also [30]. A recent report in young adults born small for gestational age suggested that IGFBP-2 could be a cardiovascular risk marker in later life [31]. However, these findings in adults are all related to serum concentrations in later life compared to our subjects, and it is yet unknown whether cord serum concentrations could anticipate later findings.

Altogether, our findings related to IGF-II and IGFBP-2 still suggest an important role of insulin, although our analyses suggested an indirect and not a major effect. Cortisol and IL-6 in the fetus at birth, do not seem to have a major role in determining birth size, however, the model did not exclude completely an effect which could also be indirect. Interestingly, our recent data show a positive effect of insulin placental concentration on both birth length and weight (unpublished), although the major effect would be mediated through cortisol placental concentration.

In conclusion, the findings of this pilot study evidenced a relationship, in particular, of IGF-II and IGFBP-2 cord serum concentrations with birth size, and also could suggest a possible relationship of fetal size with insulin sensitivity in later life, as previous clinical observations have hypothesized [32].

Acknowledgments

The authors are indebted to Dr. M. Rossi, and to Prof. O. Rossi and Dr. A. Pecci for professional statistical advice and analysis. The authors are grateful to the nurses of our local growth clinic, A. Pantaleo and C. Stamciullescu for helping with the collection of clinical data and measurements.

Author Contributions

Conceived and designed the experiments: MES. Performed the experiments: AS MP MAZ MES . Analyzed the data: AS MES . Contributed reagents/materials/analysis tools: CV SB MES. Wrote the paper: AS MES.

References

  1. 1. Louvi A, Accili D, Efstradiatis A (1997) Growth-promoting interaction of IGF-II with the insulin receptor during mouse embryonic development. Dev biol 189: 33–48.
  2. 2. DeChiara TM, Robertson EJ, Efstratiadis A (1990) A growth-deficient phenotype in heterozygous mice carrying an insulin-like growth factor-II gene disrupted by targeting. Nature 344: 78–80.
  3. 3. Baker J, Liu J-P, Robertson EJ, Efstratiadis A (1993) Role of Insulin-like Growth factors in embryonic and Postnatal Growth. Cell 75: 73–82.
  4. 4. Liu JP, Baker J, Perkins AS, Robertson EJ, Efstratiadis A (1993) Mice carrying null metations of the genes encoding insulin-like growth factor-I (IGF-I) and Type-1 IGF Receptor (Igf1r). Cell 75: 59–72.
  5. 5. Street ME, Seghini P, Fieni S, Ziveri MA, Volta C, et al. (2006) Changes in interleukin-6 and IGF system and their relationship in placenta and cord blood in newborns with fetal restriction compared with controls. Eur J Endocrinol 155: 567–574.
  6. 6. Street ME, Volta C, Ziveri MA, Viani I, Bernasconi S (2009) Markers of insulin sensitivity in placentas and cord serum of intrauterine growth restricted newborns. Clin Endocrinol 71: 394–399.
  7. 7. Street ME, Viani I, Ziveri MA, Volta C, Smerieri A, et al. (2011) Impairment of insulin receptor signal transduction in placentas of intra-uterine growth-restricted newborns and its relationship with foetal growth. Eur J Endocrinol 164: 1–9.
  8. 8. Phillips DI, Barker DJ, Fall CH, Seckl , Whorwood CB, et al. (1998) Elevated plasma cortisol concentrations: a link between low birth weight and the insulin resistance syndrome? J Clin Endocrinol Metab 83: 757–760.
  9. 9. Anagnostis P, Athyros VG, Tziomalos K, Karagiannis A, Mikhailidis DP (2009) The pathogenetic role of cortisol in the metabolic syndrome: a hypothesis. J Clin Endocrinol Metab 94: 2692–2701.
  10. 10. Mastorakos G, Chrousos GP, Weber JS (1993) Recombinant interleukin-6 activates the hypothalamic-pituitary-adrenal axis in humans. J Clin Endocrinol Metab 77: 1690–1694.
  11. 11. Cianfarani S, Germani D, Rossi L, Argirò G, Boemi S, et al. (1998) IGFI and IGF- binding protein-1 are related to cortisol in human cord blood. Eur J Endocrinol 138: 524–9.
  12. 12. Cianfarani S, Geremia C, Scott CD, Germani D (2002) Growth, IGF system, and cortisol in children with intrauterine growth retardation: is catch-up growth affected by reprogramming of the hypothalamic-pituitary-adrenal axis? Pediatr Res 51: 94–99.
  13. 13. Gagliardi L, Macagno D, Pedrotti D, Coraiola M, Furlan R, et al. (1999) Weight, Length, and head circumference at birth of a North-eastern Italian population. Report of the ad hoc committee of the Italian Society of Neonatology. It J Paediatr 25: 159–169.
  14. 14. Verhaeghe J, Van Bree R, Van Herch E, Laureys J, Bouillon R (1993) C-peptide, insulin-like growth factor binding protein-1 in umbilical cord serum: correlation with birth weight American. J Obstet Gynecol 169: 89–97.
  15. 15. Giudice LC, Zegher F, Gargosky SE, Dsupin BA, Fuenties L (1995) Insulin-like growth factors and their binding proteins in the term and preterm human fetus and neonate with normal and extremes of intrauterine growth. J Clin Endocrinol Metab 80: 1548–1555.
  16. 16. Osario M, Torres J, Mooya F, Pezzullo J, Salafia C (1996) Insulin-like growth factors (IGFs) and IGF binding proteins-1, -2 and -3 in newborn serum: relationship to feto-placental growth at term. Early Hum Dev 46: 15–26.
  17. 17. Hung TY, Lin CC, Hwang YS, Lin SJ, Chou YY, et al. (2008) Relationship between umbilical cord blood insulin-like growth factors and anthropometry in term newborns. Acta Paediatr Taiwan 49: 19–23.
  18. 18. Reece EA, Wiznitzer A, Le E, Homko CJ, Behrman H, et al. (1994) The relation between human fetal growth and fetal blood levels of insulin-like growth factors I and II, their binding proteins, and receptors. Obstet Gynecol 84: 88–95.
  19. 19. Louvi A, Accili D, Efstratiadis A (1997) Growth-promoting interaction of IGF-II with the insulin receptor during mouse embryonic development. Develop Biol 189: 33–48.
  20. 20. DeChiara TM, Efstratiadis A, Robertson EJ (1990) A growth-deficiency phenotype in heterozygous mice carrying an insulin-like growth factor II gene disrupted by targeting. Nature 345: 78–80.
  21. 21. Hartnett L, Glynn C, Nolan CM, Grealy M, Byrnes L (2010) Insulin-like growth factor-2 regulates early neural and cardiovascular system development in zebrafish embryos. Int J Dev Biol 54: 573–583.
  22. 22. White YA, Kyle JT, Wood AW (2009) Targeted gene knockdown in zebrafish reveals distinct intraembryonic functions for insulin-like growth factor II signalling. Endocrinology 150: 4366–4375.
  23. 23. Adkins RM, Somes G, Morrison JC, Hill JB, Watson EM, et al. (2010) Association of birth weight with polymorphisms in the IGF2, H19, and IGF2R genes. Pediatr Res 68: 429–434.
  24. 24. Kaku K, Osada H, Seki K, Sekiya S (2007) Insulin-like growth factor 2 (IGF2) and IGF2 receptor gene variants are associated with fetal growth. Acta Paediatr 96: 363–367.
  25. 25. D'Ercole AJ (1999) Mechanisms of in utero overgrowth. Acta Paediatr Suppl 428: 31–36.
  26. 26. Lo HC, Tsao LY, Hsu WY, Chi CY, Tsai FA (2005) Changes in serum insulin-like growth factors, not leptin, are associated with postnatal weight gain in preterm neonates JPEN. J Parenter Enteral Nutr 29: 87–92.
  27. 27. Heald AH, Kaushal K, Siddals KW, Rudenski AS, Anderson SG, et al. (2006) Insulin-like growth factor binding protein-2 (IGFBP-2) is a marker for the metabolic syndrome. Exp Clin Endocrinol Diabetes 114: 371–376.
  28. 28. Arafat AM, Weickert MO, Frystyk J, Spranger J, Schofl C, et al. (2009) The role of insulin-like growth factor (IGF) binding protein-2 in the insulin-mediated decreases in IGF-I bioactivity 94: 5093–5101.
  29. 29. Wheatcroft SB, Kearney MT (2009) IGF-dependent and IGF-independent actions of IGF-binding protein-1 and -2: implications for metabolic homeostasis. Trends Endocrinol Metab 20: 153–162.
  30. 30. Hedbacker K, Birsoy K, Wysocki RW, Asilmaz E, Ahima RS, et al. (2010) Antidiabetic effects of IGFBP-2, a leptin-regulated gene. Cell Metab 11: 11–22.
  31. 31. De kort SWK, Van Doorn K, Van de Sande AGM, Leunissen RWJ, Hokken-Koelega ACS (2010) Serum insulin-like growth factor-binding protein-2 levels and metabolic and cardiovascular risk factors in young adults and children born small for gestational age. J Clin Endocrinol Metab 95: 864–871.
  32. 32. Barker DJ, Gluckman PD, Godfrey KM, Harding JE, Owens JA, et al. (1993) Fetal nutrition and cardiovascular disease in adult life. Lancet 341: 938–941.