From in vitro probiotic strain selection and beyond

The oral microbiota plays a crucial role in both oral and systemic health, implicated in various diseases such as caries, periodontitis, and even systemic conditions like cardiovascular diseases and autoimmune disorders. Probiotics, along with lifestyle changes, are essential for restoring microbial balance and reducing the growth of opportunistic pathogens, also addressing concerns related to antibiotic resistance. Furthermore, vitamin D has emerged as a potential factor in promoting microbial balance and offering protection against cardiovascular and autoimmune diseases while reducing inflammation. This Ph.D. project investigated the effects of probiotics on counteracting oral pathogen prevalence and virulence through three milestones. Initially, eight probiotic strains were tested against opportunistic pathogens growth, viability, biofilm formation, and co-aggregation, revealing differential activity based on growth conditions. Subsequently, selected probiotics improved periodontopathogen-infected oral tumoral cell viability and reduced IL-6 production, with vitamin D potentially enhancing these effects. A preliminary experiment explored pathogen-induced DNA damage, while a clinical study involving oral lichen planus-affected patients showed promising results in increased serum vitamin D levels and changes in salivary microbiota composition post-probiotic and vitamin D supplementation. These findings suggest the potential of probiotics in managing oral dysbiosis and improving clinical outcomes for patients with oral morbidities, though further research is needed to understand probiotic metabolite mechanisms and the role of oral pathogens in oral carcinogenesis.