Kynurenine Pathway in Parkinson's Disease

NCT07272564 | Completed

• 1 other identifier: 1082
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

Parkinson's disease is a slowly progressing disease that affects the motor and non-motor functions of an individual. Periodontitis is an inflammatory chronic disease resulting in the destruction of tooth supporting structures. Inflammation has been identified as an important factor in both diseases. Given this common mechanism, the question arises as to how they may affect each other when both diseases occur together. In this study, we compared the metabolism of tryptophan, a natural amino acid of the human body, and observed whether such a process provides a biological link between periodontitis and Parkinson's disease. We extracted the saliva and blood samples of patients of Parkinson's disease and periodontitis, patients of periodontitis and healthy human beings. Comparisons between the three were made, and it was found that levels of some metabolites of tryptophan were higher in the patients of both diseases. These findings raise the possibility of a close biological connection between periodontal and brain health. Through an increased understanding of this connection in the future, new approaches for diagnosis and treatment of Parkinson's disease and periodontitis may be developed.

Conditions

Periodontal Diseases; Inflammation

Keywords

periodontal disease; Tryptophan; Kynurenine

Outcome Measures

Primary Outcomes (3)

• Pocket probing depth

  Measurement of the depth of a sulcus or periodontal pocket determined by measuring distance from a gingival margin to the base of the sulcus or pocket with a calibrated periodontal probe.

  6 months

• Clinical attachment level

  Clinical attachment level (or loss, CAL) is a more accurate indicator of the periodontal support around a tooth than probing depth alone. CAL is measured from a fixed point on the tooth that does not change, the CEJ. To calculate CAL, two measurements are needed: distance from the gingival margin to the CEJ and probing depth. In recession: probing depth (+) gingival margin to the CEJ (add). In tissue overgrowth: probing depth (-) gingival margin to the CEJ (subtract)

  6 months

• Bleeding on probing

  referring to bleeding that is induced by gentle manipulation of the tissue at the depth of the gingival sulcus, or interface between the gingiva and a tooth.

  6 months

Secondary Outcomes (1)

• Saliva and serum samples processing and analyses

  1 month

Study Arms (2)

Active Comparator

ACTIVE COMPARATOR

Saliva and serum collection of patients and samples molecules analysis

Other: Saliva and serum sampling

Experimental

EXPERIMENTAL

Samples were analyzed for TRP, KYN, KYN/TRP ratio, KYNA, 3OHKYN, picolinic acid (PA), and quinolinic acid (QA) by liquid chromatography-mass spectrometry. Clinical periodontal parameters \[plaque index (PI), probing pocket depth (PPD), clinical attachment loss (CAL), and bleeding on probing (BOP)\] were recorded.

Other: Saliva, serum and GCF sampling

Interventions

Saliva and serum sampling OTHER

Saliva were collected to analyze the selected markers as unstimulated samples during the early hours of the day. The saliva was centrifuged and then transferred into Eppendorf tubes. Venous puncture was performed after saliva collection and 10 mL of blood samples were collected by qualified staff from each participant. Saliva and serum were then stored at -80 °C until analysis.

Active Comparator

Saliva, serum and GCF sampling OTHER

Saliva were collected to analyze the selected markers as unstimulated samples during the early hours of the day. The saliva was centrifuged and then transferred into Eppendorf tubes. Venous puncture was performed after saliva collection and 10 mL of blood samples were collected by qualified staff from each participant. Saliva and serum were then stored at -80 °C until analysis.

Experimental

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• systemically healthy
• clinical diagnosis of periodontitis
• clinical diagnosis of periodontal health

You may not qualify if:

• history of regular use of systemic antibiotics anti-inflammatory, or antioxidant drugs (previous 3 months)
• nonsurgical periodontal treatment (previous 6 months)
• surgical periodontal treatment (previous 12 months)
• presence of\<10 teeth
• current medications affecting gingival health (calcium channel blockers, phenytoin, cyclosporine, and hormone replacement therapy)
• diabetes
• diagnosis of rheumatoid arthritis
• pregnancy
• lactating
• smoking
• excessive alcohol consumption.

Sponsors & Collaborators

• Medipol University: lead

Study Sites (1)

Istanbul Medipol University, School of Dentistry

Istanbul, Fatih, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Periodontal Diseases; Inflammation

Condition Hierarchy (Ancestors)

Mouth Diseases; Stomatognathic Diseases; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Prof Dr

Model Details: Saliva and serum samples were collected from periodontitis patients and with Parkinson's +periodontitis patients. Samples were analyzed for TRP, KYN, KYN/TRP ratio, KYNA, 3OHKYN, picolinic acid (PA), and quinolinic acid (QA) by liquid chromatography-mass spectrometry.

Study Record Dates

• First Submitted: November 26, 2025
• First Posted: December 9, 2025
• Study Start: May 15, 2022
• Primary Completion: January 10, 2023
• Study Completion: June 18, 2023
• Last Updated: December 9, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)