Lantibiotics are ribosomally synthesized and posttranslationally modified peptides (RiPPs) that are produced by bacteria. Interest in this group of natural products is increasing rapidly as alternatives to conventional antibiotics. Some human microbiome–derived commensals produce lantibiotics to impair pathogens’ colonization and promote healthy microbiomes. Streptococcus salivarius is one of the first commensal microbes to colonize the human oral cavity and gastrointestinal tract, and its biosynthesis of RiPPs, called salivaricins, has been shown to inhibit the growth of oral pathogens. Herein, we report on a phosphorylated class of three related RiPPs, collectively referred to as salivaricin 10, that exhibit proimmune activity and targeted antimicrobial properties against known oral pathogens and multispecies biofilms. Strikingly, the immunomodulatory activities observed include upregulation of neutrophil-mediated phagocytosis, promotion of antiinflammatory M2 macrophage polarization, and stimulation of neutrophil chemotaxis—these activities have been attributed to the phosphorylation site identified on the N-terminal region of the peptides. Salivaricin 10 peptides were determined to be produced by S. salivarius strains found in healthy human subjects, and their dual bactericidal/antibiofilm and immunoregulatory activity may provide new means to effectively target infectious pathogens while maintaining important oral microbiota.

Background/Objectives: Aging alters neutrophil functions, which may contribute to the progression and severity of periodontitis-related alveolar bone loss. Neutrophils play a key role in immune defense. However, the effects of aging on neutrophil functions and their contribution to periodontal disease remain unclear. This study examined age-related neutrophil dysfunction and its impact on periodontal bone loss. Methods: We used young (6 weeks old) and aged (18 months old) C57BL/6 mice to assess age-related neutrophil function. Neutrophil migration, superoxide production, phagocytic activity, and NETosis were evaluated. A peritonitis model and a ligature-induced periodontitis model were employed to investigate the relationship between neutrophil activity and alveolar bone loss. Results: Neutrophils from aged mice exhibited reduced migration toward pathogens compared to those from young mice. However, aged neutrophils showed increased superoxide production, elevated phagocytic activity, and enhanced NETosis. In the periodontitis models, these age-related neutrophil alterations coincided with accelerated alveolar bone loss in aged mice. Conclusions: The findings indicate that aging is linked to dysregulated neutrophil functions, characterized by excessive oxidative stress, heightened phagocytosis, and increased NETosis. These functional changes may contribute to immune dysregulation and tissue damage, thereby promoting age-related alveolar bone loss in periodontitis.

The dihydrorhodamine 123 assay is generally applied to measure the production of intracellular reactive oxygen species in neutrophils using flow cytometry and is considered a diagnostic evaluation for chronic granulomatous disease. In fact, there is a broad range of variables that can directly or indirectly affect test results, either individually or collectively. It is therefore crucial to identify the ideal requirements to achieve reliable results as well as using these requirements to provide standard operating procedures that should be taken into account. Therefore, we focus on aligning optimum results by comparing preanalytical and analytical phases that influence test results, such as the effect of various anticoagulants, transport and maintaining temperature (24°C or 4°C) of samples, test prime run time, appropriate solution concentrations, and effect of incubation temperature (24°C or 37°C) during the test run.