Disruption of the 12-hour ultradian rhythm in ocular surface microbiota of T2DM C57BL/6J mice.

The ocular surface (OS) microbiota exhibits a 12-h ultradian rhythm in healthy mice, essential for ocular homeostasis, yet its regulation in type 2 diabetes mellitus (T2DM), associated with ocular surface diseases, remains unclear. This study investigated the temporal dynamics of the OS microbiota in control (NC) and T2DM C57BL/6J mice over a 24-h cycle (ZT0, ZT6, ZT12, ZT18) using 16S rRNA sequencing and JTK_CYCLE analysis of diversity indices, OTU composition, and family-level abundance. In NC mice, a robust 12-h rhythm with distinct temporal patterns was observed. In contrast, T2DM disrupted this rhythmicity, with diversity indices and OTU compositions lacking temporal structure, and family-level rhythms, including those of Rhodocyclaceae and Pseudomonadaceae, altered, often shifting toward 24-h patterns in selected taxa and diversity measures. PCoA confirmed significant temporal clustering in NC but not in T2DM. These findings suggest that T2DM disrupts the 12-h ultradian rhythm of the OS microbiota, inducing complex temporal dysregulation, potentially contributing to ocular pathology, and highlight the potential of chronotherapeutic strategies to restore microbial rhythmicity and alleviate T2DM-related complications.