Nutrition and immune system: the size of the thymus as an indicator of the newborn's nutrition status

Abstract

The thymus is a central lymphatic organ reaching its largest size after the delivery. Its size is significantly affected by endogenous and exogenous negative factors. In our research, we investigated the relationship between the size of the thymus determined by sonography and anthropometric parameters as well as indexes demonstrating the nutritional status. The examined group consisted of 212 full-term newborns, all of which passed an anthropometric examination during the first five days after delivery (birth weight and length, mid-arm and head circumference). The following nutritional status indexes were calculated from estimated anthropometric dimensions: Quételet's index, Rohrer's index, birth weight-to-length ratio and mid-arm-to-head circumference ratio. The size of the thymus was assessed by sonography and expressed as the multiple of transversal width of the cranial thymus part and sagittal area of the major thymus lobe (so-called 'Thymic Index'). The Thymic Index showed a positive correlation with the majority of indicators of the newborn's nutritional status, but all of these correlations are low (Spearman correlation coefficients 0.228-0.409). The correlation of the size of thymus with the birth weight or birth weight-to-length ratio was stronger than the correlation with the Quételet's index or mid-arm circumference. The size of the thymus reflects the newborn's nutritional status assumed by anthropometry and can represent one of the "barometers of nutrition". Normal nutrition in the prenatal period plays a relatively critical role in the development of the immune system.

Abnormal immune system development and function in schizophrenia helps reconcile diverse findings and suggests new treatment and prevention strategies

“…Significant alterations in the structure of the thymus have been found, for example, in monkeys who experienced prenatal exposure to synthetic corticosteroids (Sawyer et al, 1977). In human samples, correlations have been found between the size of the thymus at birth and nutritional status (Collinson et al, 2003;Varg et al, 2011), as well as prenatal exposure to toxins such as arsenic (Raqib et al, 2009). Longerterm effects have been documented by McDade et al (2001): using data collected from a prospective longitudinal study of Fillipino children, they found a correlation between prenatal undernutrition and thymic function in adolescents that was marked by reduced thymopoietin production.…”

Faltering of prenatal growth precedes the development of atopic eczema in infancy: cohort study

“…Mechanistically, it is known that intrauterine growth restriction leads to disproportionate fetal growth and a high head to abdominal circumference ratio as a result of “brain sparing” responses, which direct nutrient-rich blood to maintain brain growth away from truncal organs including the thymus, with potential impact on immune development. Animal and human studies have linked fetal and birth anthropometric parameters indicative of undernutrition during pregnancy with smaller thymic size and impaired thymic development 12,33,34. We found that a larger fetal head circumference at 11 and 19 weeks’ gestation was linked with a higher risk of atopic eczema, with evidence of disproportionate head to abdominal circumference at 34 weeks.…”

“…Any such changes in premorbid growth may help explain the growth impairment in children with atopic eczema while also providing insights into etiology of the skin disorder. The development of inflammatory diseases such as atopic eczema is influenced by both genetic determinants and environmental exposures in early life, including poor nutrition,11,12 maternal stress,13,14 smoking,15 and microbiome-related exposures 16. With increasing evidence that atopic disease is partly determined by the fetal environment, better understanding of early life environment becomes crucial for identifying potential preventative strategies.…”

Determination of normal values of thymus tissue using neonatal sonography

“…The differences between prenatal and postnatal periods were evaluated by sonography method in intrauterine period. The studies evaluating thymus tissue in risky pregnancies in the last trimester are available in the literature [1][2][3][4][5][6]. Measurement of thymic size in the neonatal period may be useful in assessing the general immunological status of the child and response to sepsis in the neonatal period [7][8][9][10][11][12][13].…”