Background Dermatomyositis (DM) is frequently complicated with interstitial pneumonia (IP), causing increased morbidity and mortality. It is important to identify a useful serum marker associated with the progression, severity, and prognosis of DM-IP patients. Activated CD8+ T cells play an important role in the pathogenesis of DM-IP. LIGHT (the name of which is derived from ‘homologous to lymphotoxins, exhibits inducible expression, competes with herpes simplex virus glycoprotein D for herpes simplex virus entry mediator [HVEM], and expressed by T lymphocytes’) is a member of the TNF superfamily and activates CD4+ and CD8+ T cells, monocytes and macrophages, natural killer cells, immature dendritic cells, and platelets. LIGHT mainly binds to the HVEM receptor on T cells and transmits co-stimulatory signals. HVEM signals stimulated by LIGHT more strongly induce CD8+ T cells than CD4+ T cells. LIGHT has been reported as a biomarker of inflammatory diseases, such as rheumatid arthritis, ankylopoietic spondylarthritis, inflammatory bowel disease, and atopic dermatitis, but its association with the pathology of DM-IP has not been clarified.
Objectives Serum CD8+ T-cell activator, LIGHT, and Th1/Th2/Th17 cytokines were measured in DM-IP patients and compared with clinical parameters to investigate their usefulness.
Methods The correlations between the clinical findings and serum LIGHT and Th1/Th2/Th17 cytokine levels were investigated in 21 patients with DM-IP (14 with rapidly progressive IP [RPIP] and 7 with chronic IP [CIP], including 4 fatal cases of IP).
Results The median serum LIGHT level was 119 (16-335.4) pg/mL, which was higher than that in healthy control subjects and DM patients without IP. The median serum IL-6 level was 14.7 (2.4-154.5) pg/mL (n=13). The other cytokines were detected in only a few patients. The median serum LIGHT level in DM-RPIP patients (156 [49.6-335.4] pg/mL) was significantly higher than that in DM-CIP patients (94.3 [16-164.2] pg/mL) (P =0.02). The serum IL-6 level did not correlate with either progression or outcome of DM-IP. ROC curve analysis determined a serum LIGHT level of ≥120 pg/mL to be the cut-off value for the rapid progression of DM-IP. Serum LIGHT levels correlated significantly with %DLco (R =0.55, P =0.04) and total ground-glass opacity scores (R =0.72, P =0.0002). The serum LIGHT level significantly decreased to 100.5 (12.4-259.3) pg/mL 4 weeks after treatment initiation (P =0.04).
Conclusions The serum LIGHT level may be a promising marker of disease progression and severity in patients with DM-IP.
Disclosure of Interest None declared