Salivary Calprotectin and Neutrophils in Oral and Inflammatory Bowel Disease
Objectives: Calprotectin, or S100A8/A9, is a neutrophil-derived acute-phase protein complex and fecal marker of inflammatory bowel disease (IBD). We have shown that calprotectin is elevated in saliva during IBD, but it is also known to be affected by oral disease. Here we assessed the salivary concentration of calprotectin in IBD patients and controls, in relation to intestinal and oral diseases. Furthermore, we investigated salivary neutrophils as a source of calprotectin and compared their ability to secrete calprotectin between IBD patients and controls.
Methods: Twenty-one IBD patients (14 Crohn’s disease, 6 ulcerative colitis, 1 IBD-unclassified) and 20 controls were orally examined and sampled for stimulated saliva. Data regarding IBD extent, activity, and treatment was retrieved from all patients, and 15 IBD patients provided fresh fecal samples for calprotectin determination. Calprotectin concentrations were determined by an enzyme-linked immunosorbent assay and adjusted to salivary flow. Expression and secretion of calprotectin was evaluated by immunofluorescent staining and inflammatory stimulation of cultured salivary neutrophils from IBD patients and matched controls. Calprotectin abundancies in relation to intestinal and oral diseases were compared by two-sided non-parametric tests with statistical significance set at p≤0.05.
Results: Calprotectin was significantly elevated in stimulated saliva of IBD patients compared to controls (p<0.001), particularly in Crohn’s (p=0.002), and concentrations were unaffected by caries or periodontitis. Salivary calprotectin did not correlate to fecal calprotectin, nor was it affected by activity, treatment, or location of IBD. Salivary neutrophils expressed calprotectin, and patients and controls comparably secreted calprotectin in a time-dependent manner.
Conclusions: Salivary calprotectin is elevated in IBD regardless of oral disease, indicating that the effect of intestinal inflammation on salivary concentrations of calprotectin exceed that of periodontal inflammation. Furthermore, salivary neutrophils express and secrete calprotectin, suggesting that oral neutrophils may be affected by chronic intestinal inflammation.