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Pupillocynetic activity of substance P in systemic sclerosis
Angela Del Rosso1, Luca Bertinotti, Umberto Pietrini
1Department of Medicine, Section of Rheumatology, Headache, and Nephrology, University of Florence, Italy.
The Journal of Rheumatology
|June 5, 2003
Summary
Systemic sclerosis (SSc) patients show reduced pupil basal diameters and increased pupil response to Substance P (SP), particularly in the limited subtype. This indicates a specific peripheral nervous system dysfunction in limited SSc.
Area of Science:
- Ophthalmology
- Neurology
- Rheumatology
Background:
- Peripheral nervous system (PNS) dysfunctions are observed in systemic sclerosis (SSc).
- Substance P (SP) instillation causes pupil constriction (myosis) independent of the cholinergic system.
- Pupillometry can assess SP-ergic fiber function via pupil basal diameter (PBD) and response (AUC).
Purpose of the Study:
- To evaluate the state and function of SP-ergic fibers in SSc patients using pupillometry.
- To compare PBD and SP-induced myosis between SSc patients and controls.
- To investigate correlations between autoantibodies and pupillometric parameters in SSc.
Main Methods:
- Forty SSc patients (24 limited, 16 diffuse) and 40 controls underwent pupillometry.
- PBD was measured, followed by ocular instillation of SP (10-3 M) or placebo.
- Pupil response to SP (AUC) was recorded; correlations with ANA, ACA, and anti-Scl-70 were analyzed.
Main Results:
- SSc patients had significantly lower PBD than controls (p < 0.001).
- Limited SSc (lSSc) showed lower PBD than diffuse SSc (dSSc) and controls (p < 0.05).
- SP induced greater myosis in SSc (p < 0.001) and lSSc (p < 0.05) compared to controls. ACA correlated with decreased PBD and AUC (p < 0.001).
Conclusions:
- PBD is reduced in SSc patients, with a more pronounced reduction in lSSc.
- SP-induced myosis is intensified in SSc, especially in the lSSc subset.
- Findings suggest a distinct PNS dysfunction in the limited SSc subtype.