Salivary levels of MPO, MMP-8 and TIMP-1 are associated with gingival inflammation response patterns during experimental gingivitis.

AIM: This study aimed to investigate the association between salivary levels of myeloperoxidase (MPO), neutrophil elastase (NE), soluble urokinase-type plasminogen activator receptor (suPAR), matrix metalloproteinase (MMP)-8 and tissue inhibitor of matrix metalloproteinases (TIMP)-1 and gingival inflammation development during an experimental gingivitis study. METHODS: A three-week experimental gingivitis study was conducted. Clinical recordings of dental plaque biofilm (Modified Quigley Hein Plaque Index, TQHPI) and gingival inflammation (Modified Gingival Index, MGI) were made at specific time points for each of the 42 participants. Salivary levels of MPO, NE, suPAR, MMP-8 and TIMP-1 at the same time points were measured using distinct immunoassays. For data analysis growth curve modelling was employed to account for the time-varying outcome (MGI score) and the time-varying covariates (salivary marker levels, and TQHPI score). Analyses were stratified according to the MGI-score trajectory groups previously identified as 'fast', respectively 'slow' responders. RESULTS: Overall, higher MGI scores were statistically significantly positively associated with higher levels of MPO, MMP-8 and TIMP-1. Stratified analysis according to inflammation development trajectory group revealed higher levels of salivary MPO, MMP-8 and MMP-8/TIMP-1 ratio among the 'fast' responders than among 'slow' responders. None of the investigated salivary protein markers was associated with a 'slow' inflammation development response. CONCLUSIONS: Salivary levels of MPO, MMP-8 and TIMP-1 were associated with the extent and severity of gingival inflammation. While the 'fast' gingival inflammation response was associated with increased levels of MPO, MMP-8 and MMP-8/TIMP-1 ratio, the 'slow' response was not associated with any of the salivary protein markers investigated in this study. Neutrophil activity seems to orchestrate a 'fast' gingival inflammatory response among participants previously primed to gingival inflammation.

Soluble urokinase-type plasminogen activator receptor is associated with signs of periodontitis in adolescents.

Owing to its molecular stability in body fluids, soluble urokinase-type plasminogen activator receptor (suPAR) is used as a biomarker for the level of systemic inflammation. This study compares the suPAR levels in serum with those in the saliva of adolescents and evaluates their association with the periodontal conditions. Adolescents identified as screen positive (n = 87) or screen negative (n = 73) for periodontitis had saliva and serum samples taken, along with subgingival plaque samples. The concentrations of suPAR were determined in saliva and serum, and 18 microbial species and the immunoglobulin response to them was evaluated. Factor analyses were used to reduce the number of variables within each of the domains of clinical, microbiological, and immunological findings. The median salivary suPAR concentration was 13.18 [(interquartile range (IQR): 6.20-23.36] µg l-1 and was not associated with the serum suPAR levels (median 2.05; IQR: 1.62-2.46 µg l-1 ). Linear regression analysis showed that the log10 (salivary suPAR concentration) was statistically significantly positively associated with the clinical phenotype 'Periodontitis Extent' (ß = 0.28; 95% CI: 0.16-0.39) along with 'Putative periodontopathogens' (ß = 0.65; 95% CI: 0.51-0.79). The study represents the first determination of salivary suPAR concentration in a larger well-defined adolescent population. Our results suggest the potential for clinical use of suPAR in saliva as an inflammatory risk indicator/biomarker of periodontitis.

A parallel panning scheme used for selection of a GluA4-specific Fab targeting the ligand-binding domain.

A method for development of murine Fab fragments towards extracellular domains of a surface receptor is presented. The GluA4 ionotropic glutamate receptor is used as a model system. Recombinant GluA4 ectodomain comprising both the N-terminal domain (NTD) and the ligand-binding domain (LBD) in one molecule was used for immunization. A Fab-phage library was constructed and a parallel panning approach enabled selection of murine Fab fragments towards either intact ectodomain or the isolated LBD of the GluA4 receptor. One LBD-Fab (FabL9) showed exclusive selectivity for the GluA4 LBD, over a panel of LBDs from GluA2, GluK1, GluK2 and GluD2. Soluble FabL9 was produced in amounts suitable for characterization. Competitive ELISA and rat-brain immunoprecipitation experiments confirmed that the FabL9 epitope is conserved in the LBD and in the intact native receptor. By an alignment of GluA2 and GluA4, the likely binding epitope for FabL9 was predicted. This study demonstrates a simple approach for development of antibody fragments towards specific sub-domains of a large ligand-gated ion channel, and this method could be utilized for all multi-domain surface receptors where antibody domain-selectivity may be desirable. Furthermore, we present for the first time a GluA4 subtype-specific murine Fab fragment targeting the LBD of the receptor.