Complete artificial saliva alters expression of proinflammatory cytokines in human dermal fibroblasts

Complete artificial saliva (CAS) is a saliva substitute often used as a vehicle for test articles, including smokeless tobacco products. In the course of a study employing normal adult human dermal fibroblasts (HDFa) as a model in vitro, we discovered that CAS as a vehicle introduced a significant change in the expression of proinflammatory cytokines. To determine the effects of CAS on gene expression, real-time quantitative reverse-transcriptase PCR gene array analysis was used. Results indicate that robust changes in the expression of the proinflammatory cytokine interleukin 8 (IL8) and the vascular cell adhesion molecule 1 (VCAM1) occur within 5h of exposure to CAS. To determine whether CAS also alters cytokine release into the culture media, cytometric bead array assays for human inflammatory cytokines were performed. Analysis shows that CAS induced the release of IL8 and IL6. This study focused on determining which components in CAS were responsible for the proinflammatory response in HDFa. The following components were investigated: α-amylase, lysozyme, acid phosphatase, and urea. Results demonstrated that enzymatically active α-amylase induced gene expression for proinflammatory cytokines IL8, IL6, tumor necrosis factor-α, and IL1α and for VCAM1. Therefore, it is important to carefully evaluate the "vehicle effects" of CAS and its components in in vitro toxicology research.