Endoplasmic Reticulum Stress Response in Periodontal Disease

Periodontal disease will range from gingivitis, a mild and reversible gum inflammation, to periodontitis, a more advanced form that will cause irreversible destruction of the bone and tissue supporting the teeth and may lead to tooth loss if left untreated. A cellular process known as endoplasmic reticulum (ER) stress will be increasingly linked to chronic inflammatory diseases. When cells are exposed to stress, misfolded proteins will accumulate inside the endoplasmic reticulum, and cells will activate a protective mechanism called the unfolded protein response (UPR) to restore normal function. The UPR will operate through three main pathways controlled by the proteins PERK, IRE1, and ATF6. This study will investigate whether markers of ER stress and the UPR, GRP78, PERK, IRE1, ATF6, MANF, and CRELD2 along with the inflammatory marker TNF-α, will be altered in individuals with periodontal disease, and whether these changes will be associated with inflammation severity and tissue destruction. The study will include 72 systemically healthy, non-smoking adults, divided into three equal groups of 24: periodontally healthy individuals, individuals with gingivitis, and individuals with stage III grade B periodontitis. From each participant, gingival crevicular fluid and gingival tissue samples will be collected. Protein levels will be measured using ELISA, and gene expression levels will be assessed using RT-qPCR. In the periodontitis group, total amounts of GRP78, IRE1, PERK, MANF, and CRELD2 in gingival crevicular fluid are expected to be significantly higher, while their concentrations are expected to be lower. Protein levels of IRE1, PERK, MANF, and CRELD2 in gingival tissue, along with gene expression levels of all markers studied, are expected to be significantly elevated. ATF6 is expected to show a distinct pattern, with decreased fluid levels but increased tissue gene expression.

These findings are expected to show that ER stress and UPR pathways will be more active in the gingival tissue of individuals with periodontitis, correlating with inflammation and tissue destruction. This will help researchers identify new biological markers for periodontal disease and support future research into treatments targeting cellular stress pathways.

Inclusion criteria

Inclusion criteria

for the Healthy Control group were: presence of ≥ 20 teeth in the mouth, probing pocket depth (PPD) ≤ 3 mm, the percentage of bleeding sites for the whole mouth < 10%, and, on radiographic examination, a distance of ≤ 3 mm between the cemento-enamel junction and the alveolar bone crest in 95% of all teeth. Inclusion criteria for the Gingivitis group were: presence of ≥ 20 teeth in the mouth, PPD ≤ 3 mm, % of bleeding sites for the whole mouth ≥ 10%, and, on radiographic examination, a distance of ≤ 3 mm between the cemento-enamel junction and the alveolar bone crest in 95% of all teeth. Inclusion criteria for the Stage 3 Periodontitis group were: presence of ≥ 15 teeth in the mouth, more than 30% of teeth affected by periodontal disease, affected teeth exhibiting probing depths of 6 mm or more and clinical attachment loss (CAL) of ≥ 5 mm, vertical bone loss of 3 mm or more, class 2 or 3 furcation involvement, and radiographic evidence of alveolar bone loss extending to the middle third and beyond (33%) in the relevant teeth

Exclusion criteria

Exclusion criteria

for all groups were defined as: presence of any systemic disease, regular use of any medication, smoking, pregnancy or lactation, periodontal treatment within the last 6 months, antibiotic use within the last 6 months, and the presence of prosthetic restorations on the teeth to be sampled.