Vitamin D status and impairment of immune response to specific infections during pregnancy in three European birth cohorts

Vitamin D is a fat-soluble vitamin that acts like a hormone with multiple functions in the body. Vitamin D can come both from synthesis in the skin triggered by sun exposure and from dietary sources. While traditionally recognized for its role in regulating calcium phosphate homeostasis and mineral metabolism, vitamin D is now recognized as a pleiotropic molecule with immunomodulatory effects. Particularly, Vitamin D acts as an immune modulator, has antimicrobial and anti-inflammatory effects and helps maintain B lymphocyte homeostasis. Vitamin D interacts with its receptor in immune cells to provide a response to bacterial and viral pathogens. Vitamin D hypovitaminosis is the most common nutritional deficiency worldwide and is particularly prevalent in pregnant women. Emerging evidence has linked lower serum concentration of vitamin D with higher risk of infectious diseases such as severe COVID-19, sepsis, pneumonia and tuberculosis. Moreover, a systematic review of 25 randomized controlled trials, identified that vitamin D supplementation reduced the risk of acute respiratory infections among all participants. Scarce data exist for the period of pregnancy, which is characterized by marked immunological adaptations. Akoh et al, in a study among 158 pregnant adolescents found that participants with 25(OH)D concentrations <30 ng/mL were more likely to test positive for candida and bacterial vaginosis during pregnancy. Whether vitamin D is associated with the antibody levels of specific infections including latent infections (e.g. hepresviruses) during pregnancy has not been assessed. This might have important public health implications, as higher antibody levels could indicate a non-optimal control of these latent infections in the body. Reactivation of latent infections (e.g. CMV) during pregnancy might have long lasting effects on the developing infant. Thus, identifying modifiable factors that determine humoral responses in the period of pregnancy is of great importance both for the mother and the offspring. The aim of the project is to investigate the association between Vitamin D status during pregnancy with humoral immune responses as indicated in IgG responses to common pathogens in the INMA, BiB and Rhea cohorts