Oral intake of Heat-Killed <i>Lactiplantibacillus plantarum</i> Alleviates Bone Loss in an Ovariectomized Mouse Model Similarly to Live <i>L. plantarum</i>

Probiotics, including <i>Lactiplantibacillus plantarum</i>, have therapeutic potential to alleviate osteoporosis, which is particularly common in postmenopausal women with increasing bone fracture risk. Since live probiotics may cause adverse effects under certain conditions, such as in immunocompromised individuals, postbiotics, could be a safer alternative. In this study, we investigated whether heat-killed <i>L. plantarum</i> KCTC 10887BP (K-Lp, postbiotic form) has comparable therapeutic effects to live <i>L. plantarum</i> KCTC 10887BP (L-Lp, probiotic form) on bone loss in a mouse postmenopausal osteoporosis model. Oral administration of either L-Lp or K-Lp significantly improved bone parameters, including trabecular bone volume, thickness, and number, compared to ovariectomy (OVX) control mice. Both treatments significantly increased bone mass and bone mineral density, elevated serum procollagen 1 N-terminal propeptide levels as a marker of bone formation, and reduced the number of tartrate-resistant acid phosphatase-positive osteoclasts in femoral tissue. Furthermore, oral administration with L-LP or K-Lp increased runt-related transcription factor 2, alkaline phosphatase, and collagen type I alpha 1 chain, which are key markers for osteoblast differentiation and activation. However, no effects were observed in Sham mice. Either L-Lp or K-Lp demonstrated similar therapeutic effects against bone loss in a postmenopausal mouse model. These findings suggest that heat-killed <i>L. plantarum</i> KCTC 10887BP exhibited comparable effects to live bacteria in this OVX model, and that postbiotics could serve as a therapeutic alternative for osteoporotic bone loss.