Mode of delivery and cord blood cytokines: a birth cohort study.
BACKGROUND
The mechanisms for the association between birth by cesarean section and atopy and asthma are largely unknown.


OBJECTIVE
To examine whether cesarean section results in neonatal secretion of cytokines that are associated with increased risk of atopy and/or asthma in childhood. To examine whether the association between mode of delivery and neonatal immune responses is explained by exposure to the maternal gut flora (a marker of the vaginal flora).


METHODS
CBMCs were isolated from 37 neonates at delivery, and secretion of IL-13, IFN-gamma, and IL-10 (at baseline and after stimulation with antigens [dust mite and cat dander allergens, phytohemagglutinin, and lipopolysaccharide]) was quantified by ELISA. Total and specific microbes were quantified in maternal stool. The relation between mode of delivery and cord blood cytokines was examined by linear regression. The relation between maternal stool microbes and cord blood cytokines was examined by Spearman's correlation coefficients.


RESULTS
Cesarean section was associated with increased levels of IL-13 and IFN-gamma. In multivariate analyses, cesarean section was associated with an increment of 79.4 pg/ml in secretion of IL-13 by CBMCs after stimulation with dust mite allergen (P < 0.001). Among children born by vaginal delivery, gram-positive anaerobes and total anaerobes in maternal stool were positively correlated with levels of IL-10, and gram-negative aerobic bacteria in maternal stool were negatively correlated with levels of IL-13 and IFN-gamma.


CONCLUSIONS
Cesarean section is associated with increased levels of IL-13 and IFN-gamma, perhaps because of lack of labor and/or reduced exposure to specific microbes (e.g., gram-positive anaerobes) at birth.
Ly
Ngoc P
NP
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. ngoc.ly@channing.harvard.edu
Ruiz-Pérez
Begoña
B
Onderdonk
Andrew B
AB
Tzianabos
Arthur O
AO
Litonjua
Augusto A
AA
Liang
Catherine
C
Laskey
Daniel
D
Delaney
Mary L
ML
DuBois
Andrea M
AM
Levy
Hara
H
Gold
Diane R
DR
Ryan
Louise M
LM
Weiss
Scott T
ST
Celedón
Juan C
JC