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Dental caries is a major worldwide oral disease problem in children. Although caries are known to be influenced by dietary factors, the disease results from a bacterial infection; thus, caries susceptibility may be affected by host factors such as salivary antimicrobial peptides. This study aimed to determine a possible correlation between caries prevalence in children and salivary concentrations of the antimicrobial peptides human beta-defensin-3 (hBD-3), the cathelicidin LL37, and the alpha-defensins HNP1-3 (a mixture of HNP1, 2, 3). Oral examinations were performed on 149 middle school children, and unstimulated whole saliva was collected for immunoassays of the three peptides and for assay of caries-causing bacteria in saliva. The median salivary levels of hBD-3, LL37, and HNP1-3 were in the microgram/ml range but were highly variable in the population. While levels of LL37 and hBD-3 did not correlate with caries experience, the median HNP1-3 levels were significantly higher in children with no caries than in children with caries. Children with high caries levels did not have high levels of salivary Streptococcus mutans, and the HNP1-3 level was not correlated with salivary S. mutans. By immunohistochemistry we localized HNP1-3 in submandibular salivary duct cells. HNPs are also released by neutrophils into the gingival crevicular fluid. Both sources may account for their presence in saliva. Low salivary levels of HNP1-3 may represent a biological factor that contributes to caries susceptibility. This observation could lead to new ways to screen for caries susceptibility and to new means of assessing the risk for this common oral problem.

Female nonobese diabetic (NOD) mice develop spontaneous autoimmune sialadenitis and loss of salivary flow, and are a widely used model of Sjögren's syndrome. We examined the feasibility of local salivary gland immunomodulatory gene delivery to alter these sequelae in NOD mice. We constructed recombinant adeno-associated virus (rAAV) vectors encoding either human interleukin 10 (rAAVhIL-10) or beta-galactosidase (rAAVLacZ, control vector). Mice received rAAVhIL-10 or rAAVLacZ by retrograde submandibular ductal instillation either at age 8 weeks (early, before onset of sialadenitis), or at 16 weeks (late, after onset of sialadenitis). As a systemic treatment control, separate mice received intramuscular delivery of rAAVhIL-10 at each time point. Both submandibular and intramuscular delivery of vector led to low circulating levels of hIL-10. After submandibular administration of rAAVhIL-10, salivary flow rates at 20 weeks for both the early and late treatment groups were significantly higher than for both rAAVLacZ-administered and untreated mice. Systemic delivery of rAAVhIL-10 led to improved salivary flow in the late treatment group. Inflammatory infiltrates in submandibular glands, however, were significantly reduced only in mice receiving rAAVhIL-10 locally in the salivary gland compared with mice receiving this vector intramuscularly, or rAAVLacZ or no treatment. In addition, after submandibular rAAVhIL-10 delivery, NOD mice exhibited significantly lower blood glucose, and higher serum insulin, levels than all other groups, indicating some systemic benefit of this treatment. These studies show that expression of hIL-10 by rAAV vectors can have disease-modifying effects in the salivary glands of NOD mice, and suggest that local immunomodulatory gene transfer may be useful for managing the salivary gland pathology in Sjögren's syndrome.