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BEHANDLING-God og treffsikker diagnostikk, behandling og rehabilitering

Setting up of immunoassay for salivary carbonic anhydrase isoenzyme 6 (CA6), a putative biomarker for dental caries prediction

Awarded: NOK 0.30 mill.

Dental caries is a major global health problem affecting 60-90% of school children and nearly all adults. Estimated 2 million Norwegians have untreated caries. Individual caries increment is associated with saliva quality, especially on the amount of salivary carbonic anhydrase isoenzyme 6 (CA6). CA6 concentrations have 500-fold variation from a patient to another. Salivary CA6 concentrations are associated with caries expression but these studies are small scale or cross-sectional (only one time point). In order to clarify the effect of CA6 on caries increment we have obtained samples from a large-scale follow-up study where patients have donated saliva and attended dental examination for 8 years. We have set up a facility to measure CA6 concentrations in saliva. Our next step is to measure CA6 concentrations of the follow-up study and compare the concentrations with the caries increment of the patients. This would be the first time a salivary protein concentration is associated with caries increment in a large-scale follow-up study. Concomitantly, we are determining the daily and monthly stability of saliva quality. We have also developed two specific monoclonal antibodies to CA6 to be used in future research projects.

We have established immunoassay facility to measure concentrations of human salivary CA6. We have produced two monoclonal antibodies to human CA6 using purified human salivary CA6 provided by a collaborator. We have received REK and NSD approvals to collect saliva samples for determining the optimal time of day and methodology to collect saliva samples for CA6 measurements. We have received REK and NSD approvals plus samples from a collaborator to determine monthly intra-individual variation in salivary CA6 concentrations during a 1-year follow-up. We have agreed to a collaboration where we will receive saliva samples of a 18-year follow-up. In these samples we determine gender and age variation of CA6. Of these samples we will be able to determine also the association of CA6 concentration with caries increment. We have received REK and NSD approvals for this project.

Project summary Caries is a major oral health problem affecting 60-90% of school children and nearly all adults. If left untreated caries will progress and decrease dramatically oral-health related quality of life. Accurate caries prediction would enable efficient personalized dental care according to individuals’ needs and, thus, decrease costs to society and health disparities. Unfortunately, the existing caries prediction tools have shown only marginal clinical utility. Mice genetically modified to lack salivary carbonic anhydrase isoenzyme VI (CA6) have 75% lower caries increment than the wild-type mice. The CA6 concentration in human saliva show wide inter-individual variation from 0.1 mg/L to 16 mg/L. Therefore we plan on including patients' salivary CA6 concentration in caries prediction multivariable model to accurately predict caries increment of an individual. We will apply for ethical approval, collect saliva samples, purify CA6 from saliva, produce monoclonal antibodies and use them to set up an immunoassay for salivary CA6 concentrations. The monoclonal antibodies are needed later on A) to produce a commercial lateral flow rapid test for classifying patients into low and high risk for caries according to salivary CA6 concentrations and B) in large scale studies on salivary CA6 concentrations. Meanwhile we produce the monoclonal antibodies we will use commercially available CA6 assay kit to optimize saliva collection methodology for CA6 measurements and determine salivary CA6 concentrations in patients of different ages and genders. Once we have our own immunoassay set up and know the optimal saliva collection method we will use for the main project: i) to determine optimal cut-off point for CA6 concentrations to classify patients into high and low risk for caries, ii) validate the rapid. We will also launch an application for multivariable caries prediction.

Funding scheme:

BEHANDLING-God og treffsikker diagnostikk, behandling og rehabilitering