Determination of soluble tumor necrosis factor receptor II and secretory immunoglobulin A in saliva of patients with dementia.

The prevalence of pain and dementia increases with age, affecting a significant percentage of the population due to aging. Both pathologies are connected through the inflammatory process, specifically through the tumor necrosis factor. The effect of this cytokine is mediated through the modulation of its TNFRI and TNFRII receptors, which are linked to the dementia process. In addition, immunoglobulins such as secretory immunoglobulin A (sIgA) have been recognized as one of the main biomarkers of pain in saliva. sTNFRII and sIgA levels were determined in saliva samples by ELISA from healthy people and patients with dementia in GDS stages 5-7. The concentrations of these markers were also correlated with the GDS stage and sex. We observed a significant decrease (*** p ≤ 0.001) in the levels of sTNFRII (pg/mL) and a significant increase (** p ≤ 0.01) in the levels of sIgA (ng/mL) in the saliva of patients with dementia compared to the healthy control group. We did not observe a correlation with the data of the biomarkers regarding the GDS stage and sex. The results obtained for sTNFRII are consistent with those obtained by other authors on brain tissue, who conclude that unopposed neuronal TNFRI signaling, when TNFRII is selectively downregulated, leads to a more severe course of AD pathogenesis. Regarding sIgA, the elevated values of sIgA may reflect the immune status of these patients. Therefore, these biomarkers can provide us with relevant information through a non-invasive method such as saliva analysis.