Probiotic Lactobacillus plantarum QL01 Fights Aging by Curbing Oxidative Stress and Fixing Gut Flora

Oxidative stress is a central driver of biological aging, damaging lipids, proteins, and DNA while fueling chronic inflammation. Probiotic lactic acid bacteria have emerged as a promising dietary strategy to counter these effects, but antioxidant capacity varies dramatically by strain, necessitating strain-specific validation in vivo.

This study evaluated Lactobacillus plantarum QL01, previously screened for antioxidant activity in vitro from a library of 1,205 LAB isolates from the Qinghai-Tibet Plateau. Fifty male Kunming mice were randomly assigned to five groups: normal control (NC), D-galactose model control (MC), positive control receiving ascorbic acid (VC, 200 mg/kg/day), low-dose QL01 (LP, 1×10⁹ CFU/kg/day), and high-dose QL01 (HP, 1×10¹⁰ CFU/kg/day). All non-control groups received intraperitoneal D-galactose (125 mg/kg/day) for 8 weeks to induce accelerated aging and oxidative stress, with concurrent daily oral gavage of the assigned treatment.

In hepatic tissue, the model group showed severely depleted antioxidant defenses and elevated oxidative damage markers. QL01 intervention, especially at the high dose, significantly reversed these changes: SOD, GSH, CAT, and T-AOC activities were substantially restored (p<0.05), while MDA—a key lipid peroxidation marker—was significantly reduced. Serum cytokine analysis demonstrated that QL01 suppressed pro-inflammatory IL-6, IL-1β, and TNF-α while modulating IL-10, indicating attenuation of the systemic inflammatory response associated with D-galactose-induced aging. Histopathological examination of liver and colon tissues confirmed that QL01 reduced structural damage, including inflammatory infiltration and tissue atrophy. qPCR analysis of colonic tissue revealed improved expression of tight junction proteins, suggesting enhanced intestinal barrier function.

16S rRNA sequencing of fecal samples revealed that D-galactose induction caused significant gut microbiota dysbiosis, including an altered Firmicutes/Bacteroidetes ratio and reduced abundance of beneficial bacterial genera. QL01 supplementation partially restored microbial diversity and composition toward that of the normal control group, increasing beneficial taxa and reducing potentially pathogenic bacteria. Associated metabolite profiling further indicated restoration of gut metabolic homeostasis.

These findings position L. plantarum QL01 as a multifunctional probiotic capable of addressing three interlocked hallmarks of aging: oxidative stress, chronic low-grade inflammation, and gut dysbiosis. Notably, QL01 performed comparably or favorably to the ascorbic acid positive control across several endpoints, suggesting meaningful biological potency. The study adds mechanistic depth to the gut-liver-immune axis in aging and provides a concrete candidate strain for development of antioxidant probiotic products.