CLDN1 and obesity due to melanocortin 4 receptor deficiency: Obesity is closely linked to inflammation, as fat accumulation and localized inflammation reduce the expression of tight junction proteins (e.g., claudin-1, occludin, and ZO-1) (Chelakkot et al., 2018; Acciarino et al., 2024), thereby increasing intestinal permeability and triggering inflammation (Kim et al., 2024).