Li, Songbo. Immunomodulatory property of probiotic lactobacilli against Non-Typhoidal Salmonella enterica and Uropathogenic Escherichia Coli infections: in vitro study. Doctoral Degree(Microbiology). Chiang Mai University. Library. : Chiang Mai University, 2025.
Immunomodulatory property of probiotic lactobacilli against Non-Typhoidal Salmonella enterica and Uropathogenic Escherichia Coli infections: in vitro study
Abstract:
The contributions of lactic acid bacteria (LAB) against several human pathogens have been extensively investigated. LAB is considered one of the potential alternatives to antibiotics for preventive and therapeutic approaches for human bacterial infectious diseases. However, the strain-specific effect of the LAB plays a critical role in its outcome. Therefore, investigating new isolated strains of LAB is essential before any further application. In this study, the direct and indirect mechanisms of two new isolated LABs against non-typhoidal Salmonella (NTS) and uropathogenic Escherichia coli (UPEC) were investigated using a cell-culture model. The antibacterial and immunomodulatory activities of two Gram-positive rod-shaped probiotic LABs, Lactiplantibaillus plantarum KUNN19-2 (KUNN19-2) and Limosilactobacillus reuteri KUB AC-5 (AC5), isolated from Thai-style fermented pork (Nham) and chicken intestine, respectively against NTS and UPEC have never been investigated. Our study revealed that probiotic (viable) and paraprobiotic (heat-killed) forms of KUNN19-2 attached to human colonic epithelium (T84 cells) and inhibited the growth of several serovars of MDR clinical isolated strains of NTS. Pretreatment with probiotic and paraprobiotic form of KUNN19-2 enhanced murine macrophage (RAW264.7 cells) killing activity and pro-inflammatory (Mip-2, Nos2) and anti-inflammatory (Il10) gene expressions in vitro. We found that heat-inactivation conditions (121 °C for 15 min under 15 psi) could kill KUNN19-2 but preserve its morphology. Heat-inactivated form of KUNN19-2 did not pose a direct anti-Salmonella effect. However, it showed an indirect anti-Salmonella effect by enhancing macrophage killing activity and pro-inflammatory cytokine expressions closed to its viable form. Paraprobiotic KUNN19-2 might be developed as an alternative treatment against MDR Salmonella by host immunomodulatory effect. Another study reported that viable KUB AC-5 can adhere to human urothelium (UM-UC-3 cells) and inhibited the growth of several strains of UPEC. Pretreatment with AC-5 enhanced macrophage (RAW264.7 cells) killing activity and proinflammatory (Nos2, Il6, and Tnfa) and anti-inflammatory (Il10) gene expression. expressions. These data indicate the potential role of the immunomodulatory activity of KUNN19-2 and AC-5 against NTS and UPEC infections in humans.