LOSS OF CLDN5 -AND INCREASE IN IRF7- IN THE HIPPOCAMPUS AND CEREBRAL CORTEX OF DIABETIC MICE AT THE EARLY SYMPTOMATIC STAGE.

Analyzing changes in gene expression within specific brain regions of individuals with Type 2 Diabetes (T2DM) who do not exhibit significant cognitive deficits can yield valuable insights into the mechanisms that may underlie the progression toward a more severe phenotype, for example as when individuals age. Here, we present evidence that adult mice with long-term type 2 diabetes mellitus (T2DM) and minor cognitive deficits display alterations in the expression of 27 genes in the cerebral cortex and 16 genes in the hippocampus compared to non-T2DM mice. Only six of these genes undergo the same type of change both in the cortex and hippocampus: Interferon regulatory factor 7 (Irf7), Hypoxia-inducible factor 3 alpha (Hif-3α), period circadian clock 2 (Per2), xanthine dehydrogenase (Xdh), and Transforming growth factor β-stimulated clone 22/TSC22 (Tscd3) are all upregulated, while Claudin-5 (Cldn5) is downregulated. At the protein level, Claudin5 and IRF7 showed equivalent changes: downregulation of CLDN5 and upregulation of IRF7. These results suggest that cognitive deficits linked to chronic T2DM may stem from compromised blood-brain barrier integrity and an abnormal inflammatory response in the early stages of the disease. This underscores the potential for therapeutic interventions targeting CLDN5 and IRF7.