Gestational folic acid-deficiency alters embryonic eye development: possible role of basement membrane proteins in eye malformations

Abstract Purpose Folic acid (FA) is crucial before and during early pregnancy. FA deficiency can occur because dietary FA intake is low in mothers at the time of conception. Likewise, various ocular pathologies are related to the alteration of extracellular matrices. The present study aimed to investigate the association between maternal FA-deficiency and congenital eye defects. We also intend to investigate whether maternal diet deficient in FA alters the expression of collagen IV and laminin-1 as a possible mechanism responsible for the appearance of ocular malformations. Both proteins are the main components of the basal lamina and form an interlaced network that creates a relevant scaffold basement membrane. Basal laminae are involved in tissues maintenance and implicated in regulating many cellular processes. Methods A total of 57 mouse embryos were classified into the following groups: control group where mothers were fed standard rodent diet and D2 and D8 groups where mothers were fed FA-deficient (FAD) diet for 2 or 8 weeks, respectively. Females from group D2 were fed an FAD diet (0 mg/kg diet + 1% succinyl sulfathiazole used to block the synthesis of FA) for 2 weeks from the day after mating until day 14.5 of gestation (E 14.5). On the other hand, females from group D8 were fed an FAD diet for 8 weeks: 6 weeks before conception and during the first 2 weeks of pregnancy. For data analysis, first, we estimated the incidence of malformations in each group. Then, statistical analysis was performed using IBM SPSS Statistics V25.0. Expression patterns of collagen IV and laminin-1 were examined by immunohistochemical technique. Results Our results showed that mice born to FA-deficient mothers had several congenital eye abnormalities. Embryos from dams fed a short-term FA deficient diet were found to have many significantly abnormalities in both anterior and posterior segments, as well as choroidal vessel abnormalities. However, embryos from dams fed a long-term FA deficient diet had a significantly higher incidence of eye defects. Finally, maternal FA-deficiency increased the expression of both collagen IV and laminin-1. Likewise, changes in the spatial localization and organization of collagen IV were observed. Conclusions Maternal FA-deficient diet for a short-term period causes eye developmental defects and induces overexpression of both collagen IV and laminin-1. Malformations observed are probably related to alterations in the expression of basement membrane proteins.