Increased postnatal concentrations of pro-inflammatory cytokines are associated with reduced IGF-I levels and retinopathy of prematurity

OBJECTIVE: Retinopathy of prematurity (ROP) is a multifactorial disease linked to low insulin-like growth factor (IGF)-I levels and perhaps to postnatal inflammation. Here, we investigated the longitudinal postnatal serum concentrations of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α in relation to IGF-I levels and ROP. DESIGN: The study cohort included 52 infants born before 31 gestational weeks. The infants were screened for ROP and classified as non-ROP (n = 33), non-proliferative ROP (stages 1 and 2; n = 10), or proliferative ROP (stage 3, all treated for ROP; n = 9). Blood samples were collected at birth, 24 h after birth, and then weekly until at least 36 weeks postmenstrual age (PMA) (i.e., up to 13 weeks after birth). Circulating levels of IL-6 and TNF-α were evaluated in relation to circulating IGF-I levels and ROP. RESULTS: IL-6 levels negatively correlated with IGF-I levels between 5 and 8 weeks after birth, (p < 0.01 to p < 0.05). At birth, the IL-6 and TNF-α levels were similar independent of later ROP. Twenty-four hours after birth, both IL-6 and TNF-α levels had increased in infants later treated for ROP (p < 0.05). Postnatal, infants treated for ROP had higher IL-6 levels than infants without ROP. CONCLUSIONS: The pro-inflammatory response is associated with low IGF-I levels and the development of ROP.