Circulating levels of Nepsilon-(carboxymethyl)lysine are increased in systemic sclerosis.
OBJECTIVE
Advanced glycation endproducts (AGEs), including Nepsilon-(carboxymethyl)lysine-protein adducts (CML) are involved in micro/macrovascular changes and are co-localized with adhesion molecules in inflamed tissues. Serum levels of CML were investigated in systemic sclerosis (SSc) characterized by microvascular modifications and correlated with indices of micro/macrovascular damage.


METHODS
In 66 SSc patients (limited SSc, n = 55; diffuse SSc, n = 11) and 20 controls, CML serum levels were measured by enzyme-linked immunosorbent assay. Nailfold capillaroscopy, intima-media thickness (IMT) and the ankle-brachial index (ABI) were also recorded, to characterize micro/macrovascular involvement.


RESULTS
CML levels were significantly higher in SSc (79.2 +/- 39 mg/ml vs 49.6 +/- 26.1 mg/ml, mean +/- s.d.; P<0.01), without significant differences between SSc subsets. CML levels were significantly higher in all capillaroscopic patterns: the 'early' pattern showed higher levels than 'active' and 'late' patterns. IMT was significantly higher in SSc (P<0.01) than in controls, whilst ABI was no different from controls.


CONCLUSIONS
These data indicate that although both CML formation and macrovascular involvement are increased in SSc, there is no correlation between these two parameters. However, the characteristic early nailfold capillaroscopy changes of SSc are associated with proportionally greater CML formation, suggesting that AGEs are involved in SSc microangiopathy.
Kaloudi
O
O
Department of Medicine, Division of Rheumatology, University of Florence, Florence, Italy.
Basta
G
G
Perfetto
F
F
Bartoli
F
F
Del Rosso
A
A
Miniati
I
I
Conforti
M L
ML
Generini
S
S
Guiducci
S
S
Abbate
R
R
Pignone
A
A
Castellani
S
S
Livi
R
R
De Caterina
R
R
Matucci-Cerinic
M
M
D000328:Adult; D000368:Aged; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D017127:Glycation End Products, Advanced / Q000097:blood; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000097:blood; D008297:Male; D008833:Microcirculation; D020678:Microscopic Angioscopy; D008875:Middle Aged; D012595:Scleroderma, Systemic / Q000097:blood* / Q000473:pathology / Q000503:physiopathology; D017539:Tunica Intima / Q000473:pathology; D017540:Tunica Media / Q000473:pathology
D017127:Glycation End Products, Advanced; C048496:N(6)-carboxymethyllysine; D008239:Lysine