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NCT Number: NCT07601685

MERC Proteins in Saliva and GCF in Periodontal Disease (ELISA Study)

This observational cross-sectional study investigates the levels of mitochondria-endoplasmic reticulum contact site (MERC) proteins in saliva and gingival crevicular fluid (GCF) of individuals with different periodontal conditions. MERCs are specialized regions where mitochondria and the endoplasmic reticulum physically connect, and they play important roles in calcium signaling, oxidative stress regulation, and cell death (apoptosis). Disruption of these contact sites has been linked to inflammatory diseases, including periodontal disease.

The study includes 48 systemically healthy, non-smoking adults divided into three groups: periodontally healthy (n=16), gingivitis (n=16), and Stage III Grade B periodontitis (n=16). Five MERC-associated proteins (VAPB, PTPIP51, IP3R, GRP75, and VDAC) are measured in GCF and saliva samples using ELISA. Additionally, caspase-3 (a marker of apoptosis), reactive oxygen species (a marker of oxidative stress), and calcium levels are measured to explore relationships between MERC proteins and key cellular processes involved in periodontal tissue destruction.

The purpose of this study is to determine whether MERC protein levels differ across periodontal conditions and to evaluate their associations with clinical periodontal parameters, oxidative stress, calcium metabolism, and apoptosis.

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Key information

Conditions

Periodontitis Ataxia Biomarker Discovery and Validation Brain Diseases Central Nervous System Diseases Cerebellar Ataxia Cerebellar Diseases Congenital, Hereditary, and Neonatal Diseases and Abnormalities Dyskinesias Genetic Diseases, Inborn Gingival Diseases Gingivitis Gingivitis and Periodontal Diseases Heredodegenerative Disorders, Nervous System Infections Mouth Diseases Nervous System Diseases Neurodegenerative Diseases Neurologic Manifestations Pathways Periodontal Diseases Spinal Cord Diseases Spinocerebellar Ataxias Spinocerebellar Degenerations Stomatognathic Diseases

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Inönü University Faculty of Dentistry, Department of Periodontology

Malatya, 44210, Turkey (Türkiye)

About this study

Mitochondria-endoplasmic reticulum contact sites (MERCs) are specialized structural domains that physically link mitochondria and the endoplasmic reticulum. These contact sites are enriched with functional proteins that coordinate calcium transfer between the two organelles, regulate lipid metabolism, modulate oxidative stress responses, and control apoptotic signaling pathways. Key MERC-associated proteins include VAPB (vesicle-associated membrane protein-associated protein B), PTPIP51 (protein tyrosine phosphatase-interacting protein 51), IP3R (inositol 1,4,5-trisphosphate receptor), GRP75 (glucose-regulated protein 75), and VDAC (voltage-dependent anion channel). The IP3R-GRP75-VDAC complex facilitates calcium transfer from the ER to mitochondria, while the VAPB-PTPIP51 complex modulates this process and influences ATP production and autophagy. Disruption of MERC homeostasis has been implicated in neurodegenerative diseases, metabolic disorders, and periodontal disease. Periodontal disease is a chronic inflammatory condition driven by microbial dental plaque, leading to destruction of periodontal tissues and alveolar bone. Previous studies demonstrated dysregulation of MERC-related gene expression (MFN1, IP3R, GRP75, PINK1, SIGMAR1) in human gingival fibroblasts exposed to Porphyromonas gingivalis and Fusobacterium nucleatum.

The present study measures the concentrations and total amounts of five MERC proteins-VAPB, PTPIP51, IP3R, GRP75, and VDAC-together with caspase-3 (an apoptosis marker), reactive oxygen species (ROS, an oxidative stress marker), and calcium levels in gingival crevicular fluid (GCF) and unstimulated whole saliva obtained from systemically healthy, non-smoking participants. Participants are classified into three groups according to the 2017 World Workshop classification: periodontally healthy (n=16), gingivitis (n=16), and Stage III Grade B periodontitis (n=16), with equal sex distribution (8 males and 8 females per group). GCF samples are collected from three single-rooted teeth per participant using standardized paper strips (Periopaper), with absorbed volume measured using a Periotron 8000. Saliva samples are collected using the passive drooling method. Biomarker levels are quantified using commercially available ELISA kits. Clinical periodontal parameters recorded include Plaque Index (PI), Gingival Index (GI), Probing Depth (PD), Bleeding on Probing (BOP%), and Clinical Attachment Level (CAL). Correlations between biomarker levels and clinical parameters are analyzed. Receiver operating characteristic (ROC) curve analysis is performed to evaluate the diagnostic potential of the biomarkers.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Systemically healthy individuals aged 18-65 years
  • Non-smokers or smoking cessation more than 5 years ago
  • Healthy group: No history of periodontal disease, ≥20 teeth, probing depth (PD) ≤3 mm at all sites, bleeding on probing (BOP) <10%, radiographic CEJ-to-alveolar bone crest distance ≤3 mm in ≥95% of teeth
  • Gingivitis group: No history of periodontal disease, ≥20 teeth, PD ≤3 mm at all sites, BOP ≥30%, radiographic CEJ-to-alveolar bone crest distance ≤3 mm in ≥95% of teeth
  • Periodontitis group: ≥15 teeth, >30% of teeth affected by periodontal disease, PD ≥6 mm, clinical attachment loss (CAL) ≥5 mm, vertical bone loss ≥3 mm, Class II or III furcation involvement, radiographic alveolar bone loss extending to the middle third or beyond (≥33%), bone loss-to-age ratio between 0.25 and 1.00

Exclusion criteria

  • Periodontal treatment or antibiotic use within the past 6 months
  • Fewer than 20 teeth (excluding third molars)
  • Presence of any systemic disease
  • Current smoking or cessation within the past 5 years
  • Use of immunosuppressive medication
  • Alcohol consumption
  • Regular medication use
  • Pregnancy or lactation
  • Need for antibiotic prophylaxis prior to dental procedures
  • Prosthetic restorations on the teeth selected for sampling

Treatment and study plan

ELISA Biomarker Analysis

Diagnostic Test

Levels of MERC-associated proteins (VAPB, PTPIP51, IP3R, GRP75, VDAC), caspase-3, reactive oxygen species, and calcium were measured in gingival crevicular fluid and unstimulated whole saliva samples using commercially available ELISA kits. Absorbance was read at 450 nm. No therapeutic intervention was applied; this is an observational biomarker measurement study.

Calcium Measurement

Diagnostic Test

Calcium levels were measured in gingival crevicular fluid and unstimulated whole saliva samples using a commercially available ELISA kit (ELK Biotechnology, China). Concentrations were expressed as μmol/mL and total amounts as μmol/30s. Analytical range: 0.15-40 μmol/mL. No therapeutic intervention was applied.

Primary outcomes

  1. GCF VAPB Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of VAPB in gingival crevicular fluid measured by ELISA.

  2. Salivary VAPB Levels

    Time frame: At baseline (single visit)

    Concentrations of VAPB (pg/mL) in unstimulated whole saliva measured by ELISA.

  3. GCF PTPIP51 Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of PTPIP51 in gingival crevicular fluid measured by ELISA.

  4. Salivary PTPIP51 Levels

    Time frame: At baseline (single visit)

    Concentrations of PTPIP51 (ng/L) in unstimulated whole saliva measured by ELISA.

  5. GCF IP3R Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of IP3R in gingival crevicular fluid measured by ELISA.

  6. Salivary IP3R Levels

    Time frame: At baseline (single visit)

    Concentrations of IP3R (ng/mL) in unstimulated whole saliva measured by ELISA.

  7. GCF GRP75 Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of GRP75 in gingival crevicular fluid measured by ELISA.

  8. Salivary GRP75 Levels

    Time frame: At baseline (single visit)

    Concentrations of GRP75 (ng/mL) in unstimulated whole saliva measured by ELISA.

  9. GCF VDAC Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of VDAC in gingival crevicular fluid measured by ELISA.

  10. Salivary VDAC Levels

    Time frame: At baseline (single visit)

    Concentrations of VDAC (ng/mL) in unstimulated whole saliva measured by ELISA.

  11. GCF Caspase-3 Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of caspase-3 (ng/mL) in gingival crevicular fluid measured by ELISA.

  12. Salivary Caspase-3 Levels

    Time frame: At baseline (single visit)

    Concentrations of caspase-3 (ng/mL) in unstimulated whole saliva measured by ELISA.

  13. GCF Reactive Oxygen Species Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of reactive oxygen species (ROS) in gingival crevicular fluid measured by ELISA.

  14. Salivary Reactive Oxygen Species Levels

    Time frame: At baseline (single visit)

    Concentrations of reactive oxygen species (ROS) in unstimulated whole saliva measured by ELISA.

  15. GCF Calcium Levels

    Time frame: At baseline (single visit)

    Concentrations and total amounts of calcium (µmol/mL) in gingival crevicular fluid measured by ELISA.

  16. Salivary Calcium Levels

    Time frame: At baseline (single visit)

    Concentrations of calcium (µmol/mL) in unstimulated whole saliva measured by ELISA.

  17. Plaque Index

    Time frame: At baseline (single visit)

    Plaque Index (PI) recorded at sampling sites.

  18. Gingival Index

    Time frame: At baseline (single visit)

    Gingival Index (GI) recorded at sampling sites.

  19. Probing Depth

    Time frame: At baseline (single visit)

    Probing Depth (PD) recorded at sampling sites.

  20. Bleeding on Probing

    Time frame: At baseline (single visit)

    Bleeding on Probing (BOP%) recorded at sampling sites.

  21. Clinical Attachment Level

    Time frame: At baseline (single visit)

    Clinical Attachment Level (CAL) recorded at sampling sites.

  22. Gingival Crevicular Fluid Volume

    Time frame: At baseline (single visit)

    Gingival crevicular fluid (GCF) volume measured at sampling sites.

Sponsors and collaborators

Lead sponsor

Inonu University

Other

Collaborators

  • Harvard University
  • University of Minnesota

Registry information

Official study title

Expression of Mitochondria-Endoplasmic Reticulum Contact Proteins in Saliva and Gingival Crevicular Fluid in Patients With Periodontal Disease: ELISA and Calcium Analysis

Acronym: EKNMERC-GCF-SL

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
May 22, 2026
Registry last updated
May 22, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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