Antiendothelial cell antibodies induce apoptosis of bone marrow endothelial progenitors in systemic sclerosis.
OBJECTIVE
Patients with systemic sclerosis (SSc) have significantly fewer and functionally impaired endothelial progenitor cells (EPC) in peripheral blood and bone marrow; further, endothelial apoptosis seems to play a primary role in the pathogenesis of vascular damage. We investigated whether the failure of bone marrow EPC is related to their apoptotic phenotype and analyzed the possible mechanisms inducing apoptosis.


METHODS
The presence of apoptotic cells was investigated in bone marrow aspirates taken from patients with SSc; microvessel density (MVD) and the immunohistochemical expression of vascular endothelial growth factor (VEGF) were also measured in bone marrow biopsies. A correlation between EPC apoptosis and the presence of antiendothelial cell antibodies (AECA) was also investigated.


RESULTS
We confirmed the presence of bone marrow EPC dysfunction in SSc, while hematopoiesis was not impaired. Bone marrow studies showed a high percentage of apoptotic progenitors, no signs of fibrosis or an altered MVD, and an increased VEGF index. The patients' bone marrow plasma showed significant titers of AECA, and their presence correlated with that of apoptotic progenitors. These findings were further confirmed by an in vitro assay in which the apoptosis of normal progenitors was induced by the addition of AECA+ purified IgG.


CONCLUSIONS
Our results showed that apoptosis in patients with SSc involves the source compartment of endothelial progenitors and correlates with AECA activity. These findings support the hypothesis that AECA may play a pathogenetic role by affecting the bone marrow EPC machinery that should repair the peripheral vascular lesions.
Del Papa
Nicoletta
N
Day Hospital Reumatologia, Ospedale G. Pini, Milan, Italy. delpapa@gpini.it
Quirici
Nadia
N
Scavullo
Cinzia
C
Gianelli
Umberto
U
Corti
Laura
L
Vitali
Claudio
C
Ferri
Clodoveo
C
Giuggioli
Dilia
D
Manfredi
Andreina
A
Maglione
Wanda
W
Onida
Francesco
F
Colaci
Michele
M
Bosari
Silvano
S
Lambertenghi Deliliers
Giorgio
G
D000071916:AC133 Antigen; D000328:Adult; D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D017209:Apoptosis / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001854:Bone Marrow Cells / Q000276:immunology / Q000473:pathology*; D002478:Cells, Cultured; D005260:Female; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000276:immunology; D012595:Scleroderma, Systemic / Q000276:immunology* / Q000473:pathology*; D013234:Stem Cells / Q000276:immunology / Q000473:pathology*; D055815:Young Adult
D000071916:AC133 Antigen; D015703:Antigens, CD; D001323:Autoantibodies; D006023:Glycoproteins; D007074:Immunoglobulin G; D010455:Peptides; C087589:anti-endothelial cell antibody