title: Effect of prenatal steroid treatment on the developing immune system.
abstract: Prenatal steroids have an undisputed positive effect of decreasing neonatal morbidity and mortality by improving fetal lung maturation. Some concerns have been raised on long-term consequences on the hypothalamic-pituitary-adrenal axis and cognition, but there are no studies addressing effects on the immune system. The thymus is an essential organ for the development and selection of T cells, and thymocytes are extremely sensitive to steroids. Using a mouse model for prenatal steroid administration, we show here that betamethasone treatment to the mother has a profound effect on the thymus of the offspring. We find the thymus volume reduced, affecting mostly the developing CD4+ CD8+ double-positive thymocytes and a compensatory accelerated transition of the earlier stages to replenish the depleted compartment. This effect lasts for at least 3 days, which correspond to a very relevant period for the selection of the T cell repertoire. Moreover, we show that low doses of betamethasone have similar effects on human thymocytes in vitro. Therefore, further studies are needed to analyze possible long-term consequences of this treatment on the immune system of the offspring.
  
  
  CONCLUSIONS
  Betamethasone administered to the mother before birth reaches the fetal thymus. Prenatal betamethasone results in massive loss of developing thymocytes. The effects of betamethasone on thymus development are visible for several days. Human thymocytes are also sensitive to low doses of betamethasone. Altered thymocyte development around birth may have an effect on the immune system.
authors.affiliation: Department of Immunology, University Medical Center Hamburg-Eppendorf, Martinistrasse, 52-20246, Hamburg, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Diepenbruck
authors.forename: Chressen C
authors.initials: CC
authors.lastname: Much
authors.forename: Aniko
authors.initials: A
authors.lastname: Krumbholz
authors.forename: Manuela
authors.initials: M
authors.lastname: Kolster
authors.forename: René
authors.initials: R
authors.lastname: Thieme
authors.forename: Detlef
authors.initials: D
authors.lastname: Thieme
authors.forename: Silke
authors.initials: S
authors.lastname: Diepenbruck
authors.forename: M Emilia
authors.initials: ME
authors.lastname: Solano
authors.forename: Petra C
authors.initials: PC
authors.lastname: Arck
authors.forename: Eva
authors.initials: E
authors.lastname: Tolosa
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001623:Betamethasone / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D005260:Female; D005333:Fetus / Q000187:drug effects* / Q000196:embryology / Q000473:pathology; D005938:Glucocorticoids / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009929:Organ Size / Q000187:drug effects; D011247:Pregnancy; D013601:T-Lymphocytes / Q000187:drug effects* / Q000473:pathology; D013950:Thymus Gland / Q000187:drug effects* / Q000196:embryology* / Q000473:pathology
chemical_list: D005938:Glucocorticoids; D001623:Betamethasone