Progesterone and interleukin-8 during and after cardiopulmonary bypass in infants and children

Objectives

It has been shown that proinflammatory cytokines are suppressed by progesterone (P). cardiopulmonary bypass (CPB) leads to the release of pro- and anti-inflammatory cytokines. Because sex steroids have the ability to adsorb extensively to synthetic surfaces a decrease of P during the contact with the CPB circuit is conceivable. If P concentrations would decrease the inflammatory response to CPB could be effected. The purpose of the study was to look for the course of P in relation to the proinflammatory cytokine interleukin-8 (IL-8) during and after CPB.

Methods

Twelve infants and children (age 2 months to 15 years, median 2.4 years, four females) were operated on CPB for congenital heart disease (2 ASD, 5 VSD, 3 Fallot, subaortic stenosis, aortopulmonary window). Blood samples were taken before, during (10 min after onset) and after (disconnection, 6 and 24 h, 3 and 7 days) CPB. Plasma concentrations of P and IL-8 were determined using a RIA- and an ELISA-kit, respectively.

Results

P concentrations before CPB were 0,21 ng/ml (median, 0.012-0.72). They increased to a maximum of 5.59 ng/ml (0.13-35.4) at 6 h after CPB. The pre-CPB concentrations were reached on the 7th day post-CPB. This course of P concentrations was similar in female and male infants of every age. The maximum IL-8 concentrations were found at 6 h after CPB. The decline of IL-8 from 6 to 24 h after CPB was correlated to the P concentration at 6 h (r = 0.77).

Conclusion

The results were in contrast to our expectation because P increased with CPB. However, the significant increase with a maximum at 6 h after CPB needs further explanation. The maximal P concentrations coincided with the peak of the IL-8 response and correlated to the following decrease of IL-8. We speculate that the release of P during and after CPB could be of benefit in terminating the associated proinflammatory response. Further studies are needed to clarify the physiology and role of the P increase in the setting of CPB.