World J Microbiol Biotechnol. 2026 May 8;42(6):267. doi: 10.1007/s11274-026-05002-z.
ABSTRACT
The safety of live probiotics remains debated due to concerns regarding their viability and functional efficacy under harsh in vivo and in vitro conditions. Inflammatory bowel disease (IBD) is a complex disease stemming from various factors. It has been reported that probiotics shows anti-inflammatory function. This study evaluated the immunomodulatory and anti-inflammatory properties of heat-killed Lactobacillus strains (a form of postbiotics). Because viable Loigolactobacillus coryniformis NA-3 exhibited lower in vitro viability than Lactiplantibacillus plantarum NA, we first evaluated the phagocytic activity and TLR2-mediated immunoregulatory effects of heat-killed L. coryniformis NA-3 in RAW 264.7 cells, and conducted a preliminary comparative assessment of both live and heat-killed L. coryniformis NA-3 in murine models. We further investigated two distinct heat-killed strains: L. coryniformis NA-3 and Lactiplantibacillus plantarum NA. Heat-killed L. coryniformis NA-3 induced TLR2-dependent immunomodulatory effects in vitro and showed effects comparable to those of its live counterpart in vivo under the conditions tested. Both heat-killed strains were associated with changes in inflammatory markers, including decreased levels of pro-inflammatory cytokines (IL-6, TNF-α) and increased levels of anti-inflammatory mediators (IL-4, IL-10, TGF-β) in mice. In addition, they were associated with alterations in antioxidant parameters, including changes in SOD, GSH-Px, GR, NQO1, HO-1, Nrf2, and MDA levels, as well as increased expression of the tight junction proteins claudin-1 and occluding. Observations from this study are consistent with the potential involvement of the TLR2/NF-κB p65 signaling pathway. These findings highlight the potential of heat-killed probiotics as safe and effective alternatives to live strains in immune regulation and anti-inflammation.
PMID:42101791 | DOI:10.1007/s11274-026-05002-z
