Lacticaseibacillus rhamnosus CRL1505 Enhances Antiviral State in Respiratory Epithelial Cells and Alveolar Macrophages

Respiratory viral infections remain a major health concern, highlighting the need for strategies that enhance host antiviral defenses. Lacticaseibacillus rhamnosus CRL1505 has demonstrated beneficial immunomodulatory effects in the respiratory tract; however, its direct effects on distinct respiratory cell populations remain incompletely characterized. Here, we evaluated the capacity of live and HK 1505 to modulate antiviral immunity in porcine bronchial epithelial (PBE) cells challenged with SIV and porcine alveolar macrophage (PAM) cells infected with PRRSV. Pretreatment with either live or HK 1505 significantly reduced infectious SIV titers in PBE cells and decreased PRRSV ORF5 expression and viral antigen detection in PAM cells, accompanied by enhanced expression of interferons and antiviral factors in both models. CRL1505 also differentially modulated inflammatory responses according to the cell type. In PAM cells, both treatments enhanced proinflammatory and regulatory cytokines, whereas in PBE cells they selectively increased IL-1β and IL-6 while reducing TNF-α, IL-8, and MCP-1. Negative regulators of innate immune signaling were also differentially modulated in both cell types. Importantly, HK 1505 retained significant antiviral and immunomodulatory activities, inducing responses that were generally similar to those observed with the viable preparation under the experimental conditions evaluated. These findings demonstrate that L. rhamnosus CRL1505 enhances antiviral responses in two distinct respiratory cell models, with differences in immunomodulatory profiles that may reflect the combined influence of cellular and viral contexts.