Pediatric Rheumatology Online Journal → July 2003 → Dermatomyositis → Immunology → Abstract #118

CORRELATION BETWEEN IMMUNOHISTOCHEMICAL ANALYSIS OF ICAM-1, VCAM-1 AND C5b-9 (MAC) EXPRESSIONS WITH PERIFASCICULAR ATROPHY AND CAPILLARY DENSITY MORPHOMETRIC STUDY IN JUVENILE DERMATOMYOSITIS (JDM) MUSCLE FRAGMENTS

A. M. Sallum,¹ K. C. Costa,² A. Wakamatsu,² S. Sachetti,³ M. A. Vianna,⁴ C. A. Silva,¹ M. H. Kiss,¹ S. K. Marie.²

¹Department of Pediatrics - Pediatric Rheumatology Unit, Instituto da Crianca - Hospital das Clinicas - Universidade de Sao Paulo, Sao Paulo, SP, Brazil; ²Department of Neurology, Hospital das Clinicas - Universidade de Sao Paulo, Sao Paulo, SP, Brazil; ³Department of Pediatrics - Pediatric Rheumatology Unit, Santa Casa de Misericordia de Sao Paulo, Sao Paulo, SP, Brazil; ⁴Department of Rheumatology, Hospital das Clinicas - Universidade de Sao Paulo, Sao Paulo, SP, Brazil

Objective: To correlate ICAM-1, VCAM-1 and MAC expressions in capillaries with perifascicular atrophy and density of capillaries in JDM muscle fragments.
Patients and methods: 35 JDM patients (37 muscle fragments) were studied. Muscle biopsy specimens were prepared with monoclonal antibodies of ICAM-1, VCAM-1 and MAC (Dakopatts) by StreptABCComplex/HRP immunohistochemical procedure and expression was assessed semi-quantitatively as (-): no staining; (+): less than 25%; (++): less than 50%; (+++): less than 75% and (++++): 100% staining of capillaries analyzed.
Perifascicular atrophy was analyzed by imaging program (Cell), measuring diameter of 500 muscle fiber and number of capillaries was counted and correlated with number of fibers in all fascicles. Statistical analysis: Spearman's post (rs): p0.05.
Results: Depletion of capillaries and perifascicular atrophy was present in all cases. ICAM-1 expression was positive in 100% of muscle fragments (94.6% in capillaries), VCAM-1 in 36% (5.4% in capillaries) and MAC in 85% (51.3% in capillaries). It was found a statistical significant corelation between MAC expresssion in capillaries and perifascicular atrophy (p=0.030). No statistical significant correlation was found between ICAM-1 and MAC (p=0.828) and VCAM-1 and MAC (p=0.643) expression in capillaries and between ICAM-1 and VCAM-1 expression in capillaries and perifascicular atrophy (p=0.287 and p=0.839 respectively) and between ICAM-1, VCAM-1 and MAC expression in capillaries and fiber/capillary relation (p=0.094, p=0.588 and p=0.765 respectively).
Conclusion: The positivity of ICAM-1 expression and the correlation between MAC expression in capillaries and perifascicular atrophy strongly suggests that the endothelium is a relevant target in pathophysiology of JDM.