Investigating the impact of dolutegravir on embryonic development

Dolutegravir (DTG) is an integrase strand transfer inhibitor recommended as part of first line treatment for people living with HIV, including pregnant women. In 2018, the Botswana Harvard AIDS institute partnership noticed an increase in frequency of neural tube defects (NTDs) among babies of women taking DTG in their Tsepamo birth surveillance study. NTDs occur when neurulation fails and can affect both cranial and spinal regions. This study aimed to investigate the effect of DTG on embryonic development in neurulation stage mouse embryos and human gastruloids. Culture of wild-type mouse embryos with DTG showed no increase in NTDs, however, culturing a genetically susceptible mouse strain resulted in a significant increase in exencephaly, particularly affecting the midbrain and forebrain. Human gastruloids display symmetry breaking and axial elongation similarly to gastrulation stage human embryos. Treatment with DTG resulted in abnormalities in lineage specification and patterning. To understand the mechanism causing these abnormalities, mouse embryonic fibroblasts (MEFs) generated from the genetically susceptible strain were treated with DTG. Seahorse assays and MitoTracker dyes were used to assess energy metabolism and reactive oxygen species (ROS) production. DTG-treated MEFs showed decreased mitochondrial respiration and increased compensatory glycolysis, but not significantly. DTG-treated cells showed decreased ROS levels and increased mitochondrial network complexity. The increased rates of exencephaly observed in genetically susceptible embryos treated with DTG could not be rescued with myo-inositol supplementation, but there was preliminary evidence that folic acid may lower risk of DTG-related NTDs. This thesis suggests that DTG can significantly increase the risk of failed neural tube closure when combined with genetic susceptibility. I propose that DTG may cause gene expression changes, possibly during gastrulation, and alters energy metabolism by pushing cells to a more glycolytic state. Identifying the mechanisms causing increased NTDs will allow development of measures to reduce these abnormalities.