PTPIP51-VAPB Complex in the Periodontal Disease

Periodontal disease encompasses a spectrum of inflammatory conditions ranging from gingivitis to periodontitis, both of which are driven by the host immune response to periodontopathogenic bacteria such as Porphyromonas gingivalis. Mitochondria-associated endoplasmic reticulum membranes (MAMs) are physical contact sites between the endoplasmic reticulum and mitochondria that regulate calcium exchange, lipid metabolism, and autophagy. The VAPB-PTPIP51 tethering complex is a key molecular determinant of MAM formation, and prior research has shown that alterations in this complex affect autophagosome formation and intracellular calcium homeostasis. However, the role of the VAPB-PTPIP51 complex and autophagy-related protein LC3B in periodontal disease has not been previously characterized.

This study includes two components. First, an observational, cross-sectional investigation was conducted in 60 participants classified into three groups (periodontal health, gingivitis, and periodontitis) according to the 2017 World Workshop classification criteria, based on clinical parameters including plaque index, gingival index, probing depth, clinical attachment level, and bleeding on probing. Gingival tissue biopsies were obtained from participants undergoing clinically indicated periodontal procedures (crown lengthening, gingivectomy, or flap surgery). Tissue samples were analyzed for gene expression (RT-PCR) and protein levels (Western blot) of PTPIP51, VAPB, and LC3B, as well as tissue calcium concentration.

Second, an in vitro experimental component was performed using a commercially available human gingival fibroblast cell line (HGF-1) treated with Porphyromonas gingivalis lipopolysaccharide (LPS) at 5 μg/mL and 10 μg/mL for 24 hours, to evaluate dose-dependent changes in PTPIP51, VAPB, and LC3B gene expression in response to a periodontopathogenic stimulus.

The findings from this study aim to clarify the involvement of the VAPB-PTPIP51 tethering complex and autophagy-related signaling in periodontal tissue destruction, providing mechanistic insight that may inform future therapeutic approaches targeting mitochondria-endoplasmic reticulum communication in periodontal disease.

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