Session Type: Abstract Submissions (ACR)
Background/Purpose: Skin autofluorescence (AF) has been suggested as a non-invasive measure of oxidative stress in patients with diabetes and other diseases. We have previously shown that skin AF is also increased in patients with systemic sclerosis (SSc). As part of the disease process, patients with SSc undergo fundamental changes in their skin properties including skin thickening, alteration in perfusion secondary to microvascular dysfunction, and altered pigmentation. There are concerns that these might influence AF. The aim of this study was to determine whether skin AF is altered by these changes and thus to assess whether skin AF is a valid non-invasive technique to measure oxidative stress in SSc. This is a key question given the increasing evidence implicating oxidative stress in pathophysiology.
Methods: Twenty healthy controls (HC [2 males, median 45 (inter-quartile range 39-52) years]), 20 patients with limited cutaneous (LcSSc, [2 males, 55 (50-67) years]) and 20 with diffuse cutaneous SSc (DcSSc, [6 males, 56 (52-66) years]) participated. Skin AF, induced by ultra-violet light was measured at 10 body sites (distal and proximal digit (dorsal aspect), dorsum of hand, lower and upper arm (dorsal aspect), forehead, anterior chest and abdomen, calf and foot (dorsal aspect)). Each of the following assessments was also made: 1) dermal (skin) thickness, by high frequency ultrasound, 2) erythema index (EI, an indirect measure of blood flow) and 3) melanin index (MI, a measure of pigmentation). EI and MI were both calculated from white light reflection measurements with a spectrometer. Linear regression was used to assess the relationships between AF, skin thickness, EI and MI and SSc subtype.
Results: Linear regression confirmed previous findings that fluorescence is increased in patients with SSc as compared to controls. Patients with DcSSc showed a higher increase in AF than patients with LcSSc; data shown for one exemplar (forearm) in Table 1. Linear regression showed no associations between skin fluorescence and skin thickness, EI or MI (as shown on the last row of Table 1). No consistent differences for values of EI or MI were found between groups.
Table 1: Data for forearm for HC, LcSSc and DcSSc: mean (inter-quartile range); and linear regression at the forearm.
|Group/Method||AF (intensity, arbitrary units)||Skin thickness (micrometers)||EI (arbitrary units)||MI (arbitrary units)|
|HC||0.034 (0.030-0.048)||88 (82-103)||10.36 (7.02-11.16)||59.21 (55.32-63.23)|
|LcSSc||0.040 (0.030-0.051)||81 (62-99)||9.82 (7.77-14.05)||63.96 (55.25-66.28)|
|DcSSc||0.045 (0.034-0.060)||109 (76-126)||10.73 (9.20-14.33)||58.23 (53.40-64.80)|
Linear regression: Difference from AF (95% confidence intervals);p-value
-3.95×10-05 (-2.30×10-04 to 1.51×10-04); 0.680
7.95×10-04 (-3.84×10-04 to 1.97×10-03); 0.182
-5.11×10-04 (-1.05×10-03 to 2.57×10-05); 0.062
Conclusion: The skin changes observed in patients with SSc, as measured by high frequency ultrasound and white light reflection, do not appear to influence skin AF measurements, i.e. skin AF is independent of skin thickness, EI and MI and should therefore be a valid technique for use in the assessment of oxidative stress in SSc.
C. E. M. Griffiths,
« Back to 2012 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/skin-autofluorescence-as-a-measure-of-oxidative-stress-in-systemic-sclerosis-is-not-affected-by-skin-thickness-erythema-or-melanin/