Evaluation of Epigenetic Age Acceleration in Growth Hormone (GH)-Deficient Children After 6 Months of Recombinant Human GH Replacement Therapy: Anti-Ageing GH vs. Pro-Ageing Insulin-like Growth Factor 1 (IGF-1)?

Background: One of the most debated topics in experimental and clinical endocrinology is the impact of hypo- and hyper-somatotropism on the extension/shortening of the lifespan, the results of experimental, clinical, and epidemiological studies being extremely conflicting. Biological age, a surrogate of lifespan, can be measured through different methods, including the age-related epigenetic modifications of DNA. Objective: The present study aimed to evaluate the biological (epigenetic) age and age acceleration in a group of growth hormone (GH)-deficient (GHD) children (F/M = 5/5; age: 11.0 ± 2.7 years), treated with recombinant human GH (rhGH) for 6 months at a daily dose of 0.025-0.035 mg/kg. Results: Treatment with rhGH significantly increased height velocity and circulating insulin-like growth factor 1 (IGF-1) levels. Biological and chronological ages were significantly correlated at baseline and after 6 months of rhGH replacement therapy. Treatment with rhGH reduced age acceleration, an effect that became significant only after adjustment for IGF-1. In a linear regression model for longitudinal data, after adjustment for rhGH treatment, age acceleration was significantly associated with IGF-1 levels, an effect missing when considering the interaction rhGH treatment × age acceleration at 6 months of rhGH treatment. Conclusions: (rh)GH, when administered to GHD children, exerts anti-ageing effects, which become evident after removal of the presumably pro-ageing effects of IGF-1.