Researchers tracked intestinal barrier function across the lifespan in C57BL/6J mice and TLR4 knockout mice, revealing distinct phases of gut aging. Adult mice (2-4 months) showed peak microbiome diversity with high Bacteroidota and beneficial Akkermansia, plus optimal short-chain fatty acid production. By middle age (7-9 months), pro-inflammatory cytokines IL-1β, IL-6, and TNF-α increased while beneficial Bacteroidota declined and harmful Firmicutes expanded. Aged mice (16-19 months) exhibited blunted inflammatory responses and further microbiome deterioration. Crucially, TLR4 knockout mice were protected from this age-related decline, implicating Toll-like receptor 4 signaling as the key driver. This finding connects decades of research on gut barrier dysfunction and aging inflammation. The identification of TLR4 as a central mediator suggests targeted interventions could potentially slow gut aging and reduce systemic inflammation. However, this remains mouse-only research, and the complex interplay between genetics, diet, and environment in human gut aging likely differs significantly. The work provides a mechanistic framework but requires human validation before therapeutic applications.