Tumor necrosis factor-alpha allele lymphotoxin-alpha+250 is associated with the presence and severity of placental inflammation among preterm births.

Histologic inflammation of placenta has been associated with increased risk for bronchopulmonary dysplasia and periventricular leukomalacia among preterm infants. Tumor necrosis factor-alpha (TNF-alpha) plays a central role in the regulation of inflammation. Some alleles of TNF (LT-alpha+250, TNF-alpha-308, and TNF-alpha-238) have been associated with susceptibility and/or severity of many diseases characterized by inflammation and/or involving the immune system. To determine whether alleles of TNF-alpha affect the risk and/or the severity of chorioamnionitis, we examined the placentas of 101 preterm births (birth weight <or=1250 g) for the presence of inflammation. Maternal and fetal chorioamnionitis (MCA and FCA, respectively) were graded for severity and staged for location of inflammatory infiltrate. Analysis for TNF-alpha alleles was done using PCR-restriction fragment length polymorphism technique on DNA extracted from infants' whole blood. MCA and FCA were seen in 45 and 38 placentas, respectively (p = 0.64). Genotypes of TNF-alpha-308 did not affect the development or the severity of placental inflammation. However, the AA genotype of LT-alpha+250 occurred more often when MCA and FCA were present compared with placentas without inflammation (p = 0.016 and p = 0.007, respectively). The GA genotype of TNF-alpha-238 was more common in placentas with severe MCA than with mild MCA (p = 0.015). The number of A alleles of LT-alpha+250 (GG = 0, GA = 1, AA = 2) correlated directly and significantly with grades and stages of MCA and FCA (p < 0.05). The AA genotype of LT-alpha+250 is associated with the development of chorioamnionitis among preterm births. The A allele of LT-alpha+250 seems to worsen the degree of placental inflammation.