Ered for adjustment. It has been already demonstrated that serum cytokines

Ered for adjustment. It has been already demonstrated that serum cytokines show higher sensitivity and specificity than amniotic fluid and umbilical cord cytokines [20]. In addition, the use of these samples (collected only at birth) does not seem to have good PD98059 chemical information practical applicability for the prevention of PTB. BV was not found to be associated with the concentrations of regulatory cytokines during pregnancy or with PTB. The lack of an association between BV and PTB has been also demonstrated in previous studies [21,22], although no consensus has been established [8]. This mayPLOS ONE | DOI:10.1371/journal.pone.0158380 August 3,8 /Regulatory Cytokine and Preterm Birthbe explained by differences in the local immune responses and in genetic determinism [23], which were not investigated in these studies.Strengths and weaknessesAlthough the data for this buy FPS-ZM1 cohort are not population based, the important factor is to obtain appropriate numbers of women in each category of the variables under study in order to establish a contrast with adequate statistical power. In addition, the greater socioeconomic homogeneity of the sample represented an advantage because it reduces confounding. Besides, although cases and controls were not similar in relation to maternal age, hypertension, and drug use, these variables were considered in the adjusted analyses. Despite missing data, BV and IL-10 missings did not differ between cases and controls. However, TGF- missings were greater among cases (P = 0.024). However, analysis of sensitivity [16] showed that, even in the worst-case scenario, in case all the missing values for TGF- were above the median, non-adjusted and adjusted associations would continue to be statistically significant. These observations support validity of the findings. In case-control studies, it is difficult to ensure a correct sequence of events, however, the design nested in a prospective cohort reduces these errors. In the present study, US has been used as the gold standard for the estimation of GA, minimizing measurement bias [24]. Objective techniques were also adopted for the measurement of the principal exposures, with previous calibration of the instruments. Another advantage was the use of maternal serum, which is easily accessible and permits earlier identification of possible changes in cytokine levels.Plausibility and unanswered questionsIt is still unclear whether the inflammatory response can actually trigger PTB [25,26]. The disequilibrium between the action of pro- and anti-inflammatory cytokines can play a role in the initiation of labor through different pathways nfection, decidual hemorrhage, uteroplacental ischemia, cervical disease, and/or immunological phenomena [26]. Current evidence indicates that the equilibrium between the pro- or anti-inflammatory response is mediated by the action of IL-10 and TGF- [5]. Thus, these regulatory cytokines play an important role in the maintenance of pregnancy. Treatment with IL-10 for intra-amniotic infections in animal studies reduced uterine contractions [27]. In humans, serum IL-10 concentrations are higher in the first trimester of pregnancy and lower at term delivery and among nonpregnant controls, suggesting that a negative IL-10 regulation occurs as part of the inflammatory process necessary for term delivery [28]. Regulatory T lymphocytes and macrophages classically activated or alternatively activated in response to microbial products produce cytokines [29,30]. However, a.Ered for adjustment. It has been already demonstrated that serum cytokines show higher sensitivity and specificity than amniotic fluid and umbilical cord cytokines [20]. In addition, the use of these samples (collected only at birth) does not seem to have good practical applicability for the prevention of PTB. BV was not found to be associated with the concentrations of regulatory cytokines during pregnancy or with PTB. The lack of an association between BV and PTB has been also demonstrated in previous studies [21,22], although no consensus has been established [8]. This mayPLOS ONE | DOI:10.1371/journal.pone.0158380 August 3,8 /Regulatory Cytokine and Preterm Birthbe explained by differences in the local immune responses and in genetic determinism [23], which were not investigated in these studies.Strengths and weaknessesAlthough the data for this cohort are not population based, the important factor is to obtain appropriate numbers of women in each category of the variables under study in order to establish a contrast with adequate statistical power. In addition, the greater socioeconomic homogeneity of the sample represented an advantage because it reduces confounding. Besides, although cases and controls were not similar in relation to maternal age, hypertension, and drug use, these variables were considered in the adjusted analyses. Despite missing data, BV and IL-10 missings did not differ between cases and controls. However, TGF- missings were greater among cases (P = 0.024). However, analysis of sensitivity [16] showed that, even in the worst-case scenario, in case all the missing values for TGF- were above the median, non-adjusted and adjusted associations would continue to be statistically significant. These observations support validity of the findings. In case-control studies, it is difficult to ensure a correct sequence of events, however, the design nested in a prospective cohort reduces these errors. In the present study, US has been used as the gold standard for the estimation of GA, minimizing measurement bias [24]. Objective techniques were also adopted for the measurement of the principal exposures, with previous calibration of the instruments. Another advantage was the use of maternal serum, which is easily accessible and permits earlier identification of possible changes in cytokine levels.Plausibility and unanswered questionsIt is still unclear whether the inflammatory response can actually trigger PTB [25,26]. The disequilibrium between the action of pro- and anti-inflammatory cytokines can play a role in the initiation of labor through different pathways nfection, decidual hemorrhage, uteroplacental ischemia, cervical disease, and/or immunological phenomena [26]. Current evidence indicates that the equilibrium between the pro- or anti-inflammatory response is mediated by the action of IL-10 and TGF- [5]. Thus, these regulatory cytokines play an important role in the maintenance of pregnancy. Treatment with IL-10 for intra-amniotic infections in animal studies reduced uterine contractions [27]. In humans, serum IL-10 concentrations are higher in the first trimester of pregnancy and lower at term delivery and among nonpregnant controls, suggesting that a negative IL-10 regulation occurs as part of the inflammatory process necessary for term delivery [28]. Regulatory T lymphocytes and macrophages classically activated or alternatively activated in response to microbial products produce cytokines [29,30]. However, a.