In Vitro Insights on a Gut–Testis Axis Model by a Nutraceutical Combination of Ceratonia siliqua, Ribonucleotides and Bifidobacterium longum

Oxidative stress and environmental factors impair spermatogenesis and testicular function. The gut–testis axis has emerged as an important regulator of male reproductive health, influencing spermatogenesis beyond traditional endocrine control. This study evaluated the efficacy of a combination of Carob (Ceratonia siliqua), Bifidobacterium longum GA24, and ribonucleotides (MIX) on in vitro models of the gut–testis axis (co-culture Caco-2/HSerC on Transwell® system). At the intestinal level, MIX increased Caco-2 cell viability, improved tight junction levels, regulated ROS production, and increased butyrate synthesis beyond physiological values, highlighting improved intestinal barrier function and integrity. In the gut–testis model, HSerC cells subjected to H2O2 300 μM showed 1.5-fold increased viability, 81% reduction in ROS, increased ATP (+1.7-fold) and NO (+1.8-fold). The MIX combination reduced the apoptotic markers BAX (−1.6-fold), caspase-3 (−1.84-fold), and Cyto-C (−1.52-fold), and the inflammatory mediators TNFα and IL-6. MIX enhanced Sertoli cell maturation markers, increasing AR by 6-fold, p27 by 1.64-fold, and SGP-2 by 2.5-fold, and modulated hormonal-related markers by increasing testosterone and FSHR expression. These findings indicate that MIX may positively modulate the gut–testicular axis, supporting the intestinal barrier, testicular health, and spermatogenesis.