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[3H]PK11195 binding sites in human neutrophils: effect of fMLP stimulation and modulation in rheumatic diseases
Laura Giusti1, Laura Betti, Gino Giannaccini
1Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy.
Objective:
The objectives of this study were to evaluate the [3H]PK11195 binding parameters in a model of acute inflammation, the N-formylmethionine-leucine-phenylalanine (fMLP)-stimulated neutrophil cell membranes, and to analyze if alterations of peripheral-type benzodiazepine receptor (PBR) characteristics occurred in neutrophil cell membranes of patients affected by osteoarthritis (OA), rheumatoid arthritis (RA), and psoriasic arthritis (PA).
Design And Methods:
Neutrophils were obtained from 15 patients with OA, 15 patients with RA, and 15 patients with PA. fMLP stimulation was performed to aliquots of neutrophils from six healthy individuals. Evaluation of kinetic parameters of PBR was performed using [3H]PK11195, as specific radioligand compared with 15 healthy volunteers.
Results:
The results showed a significant decrease of Kd and Bmax in fMLP-stimulated neutrophil membranes. Moreover, an increase of PBR binding sites and affinity value was observed in neutrophils membranes from PA patients.
Conclusions:
Our data suggested a fMLP modulation on [3H]PK11195 binding in human neutrophils. Moreover, our results showed an up-regulation of PBR in neutrophils of PA patients.
Insights
Peripheral-type benzodiazepine receptor (PBR) binding is modulated by N-formylmethionine-leucine-phenylalanine (fMLP) stimulation in human neutrophils. Psoriatic arthritis patients exhibit increased PBR in neutrophil membranes.
Area of Science:
- Immunology
- Pharmacology
- Cell Biology
Background:
- Peripheral-type benzodiazepine receptor (PBR) is implicated in inflammatory processes.
- Neutrophils play a key role in acute inflammation and immune responses.
- Alterations in PBR may be associated with inflammatory arthritis.
Purpose of the Study:
- To evaluate [3H]PK11195 binding parameters in N-formylmethionine-leucine-phenylalanine (fMLP)-stimulated neutrophil membranes.
- To investigate PBR characteristics in neutrophil membranes of patients with osteoarthritis (OA), rheumatoid arthritis (RA), and psoriatic arthritis (PA).
Main Methods:
- Neutrophils were isolated from patients with OA, RA, PA, and healthy volunteers.
- fMLP stimulation was performed on neutrophils from healthy individuals.
- [3H]PK11195 was used as a radioligand to assess PBR kinetic parameters.
Main Results:
- fMLP stimulation significantly decreased Kd and Bmax in neutrophil membranes.
- Neutrophil membranes from psoriatic arthritis patients showed increased PBR binding sites and affinity.
- A modulation of [3H]PK11195 binding was observed in human neutrophils.
Conclusions:
- fMLP stimulation influences [3H]PK11195 binding in human neutrophils.
- Psoriatic arthritis is associated with an up-regulation of PBR in neutrophils.
- PBR may serve as a biomarker for psoriatic arthritis.
