C-reactive protein (CRP), a humoral component of the innate immune system with important
functions in host-defense, is extensively used as a sensitive biomarker of systemic
inflammation. During inflammation, hepatocyte-derived CRP rises dramatically in the blood
due to increased interleukin-6 (IL-6) levels. Reliable detection of CRP in saliva, instead of
blood, would offer advantages regarding sampling procedure and availability but using saliva
as a diagnostic body fluid comes with challenges. The aims of this study were to evaluate
associations between salivary CRP, total protein levels in saliva and serum CRP. Furthermore,
we examined associations with plasma IL-6, body mass index (BMI), tobacco smoking and
age. Salivary CRP was investigated by ELISA in 107 middle-aged participants from the
general population. We employed spectrophotometric determination of total protein levels.
Correlation analyses were used for associations of salivary CRP with serum CRP
(turbidimetry), plasma IL-6 (Luminex®), BMI and smoking habits. Salivary median CRP was
68% higher (p=0.009), and total protein levels were 167% higher (p<0.0001), in morning
compared to evening saliva. The correlation coefficients between serum and salivary CRP
were low to moderate, but stronger for evening than morning saliva. Plasma IL-6 correlated
significantly with serum CRP (rs=0.41, p<0.01), but not with morning or evening salivary CRP.
Non-smokers showed 103% higher salivary CRP levels (p=0.015), whereas serum CRP was
independent of smoking status. As opposed to CRP in serum, salivary CRP was not
associated with BMI. Salivary CRP was 90% higher among the age interval 60–69 years
compared to subjects aged 45–59 (p=0.02) while serum CRP levels did not differ between the
age groups. In conclusion, CRP in saliva did not straightforwardly reflect serum
concentrations. This raises questions regarding adequate reflection of biological events.
The pronounced diurnal salivary CRP pattern accentuates the importance of standardizing
the time-point of sampling.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:84288 |
| Date | 24 March 2023 |
| Creators | Wetterö, Jonas, von Löhneysen, Sarah, Cobar, Flordelyn, Kristenson, Margareta, Garvin, Peter, Sjöwall, Christopher |
| Publisher | Frontiers Research Foundation |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 1664-3224, 607166 |
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