Microbial influx during early postnatal life fortifies the ocular surface and guards against allergic eye disease in mice

Host-microbiome interplay during development governs the homeostasis of various bodily surfaces, however, postnatal colonization of the microbiome and its impact on the homeostasis of ocular surface is still unclear. Here, the changes of the conjunctival microbiome in C57BL/6 J mice were tracked in 1-week-old neonates through to 8-week-old adult mice. This disclosed that changes in the conjunctival microbiome correlate with age, especially at the 2-week and 3-week time points, which, respectively, are accompanied by eyelid-opening and weaning. Antigen presenting cells were also recruited to the conjunctival epithelium after eyelid-opening, whilst an inhibition of microbial colonization at 2-to-3 weeks of age led to a disruption of mucosal homeostasis and aggravated the development of allergic eye disease. This study improves our understanding of the development of the conjunctival microbiome in mice, and provides an indication that early microbial colonization is required for the establishment of mucosal ocular surface homeostasis, the perturbation of which leads to increased susceptibility to allergic eye disease.