Lacticaseibacillus rhamnosus CRL1505 Ameliorates Liver Injury and Inflammation in Poly(I:C)-Induced Acute Hepatitis

<i>Lacticaseibacillus rhamnosus</i> CRL1505 enhances antiviral immunity at mucosal sites, but its capacity to modulate liver immune responses remains unclear. Therefore, this study evaluated whether this immunomodulatory bacterium protects against Toll-like receptor 3 (TLR3)-mediated acute hepatitis induced by poly(I:C), and whether this effect depends on mucosal adhesion. BALB/c mice received the wild-type CRL1505 strain or the Δ<i>mbf</i> CRL1505 mutant lacking the mucus-binding factor gene prior to poly(I:C) challenge. Liver injury, serum transaminases, and hepatic expression of interferons (IFNs), antiviral factors, inflammatory mediators, and regulatory cytokines were evaluated 48 h later. Poly(I:C) challenge induced acute hepatitis characterized by increased ALT/AST levels, leukocyte infiltration, and elevated hepatic IFNs and proinflammatory cytokines. The CRL1505 strain administration significantly reduced TNF-α, IL-1β, and IL-6 while enhancing IFNs, antiviral factors, and the regulatory cytokines IL-10 and IL-27, resulting in improved transaminase levels and attenuated liver damage. Notably, the Δ<i>mbf</i> CRL1505 mutant conferred protection comparable to the wild-type strain. These findings demonstrate that <i>L. rhamnosus</i> CRL1505 exerts immunomodulatory and hepatoprotective effects during TLR3-driven hepatitis and that mbf-mediated adhesion is not required for this protection. Overall, CRL1505 emerges as a promising preventive strategy to enhance antiviral defenses and limit inflammation-associated liver injury.