• Tomoyuki Kakugawa, Hiroshi Mukae, Tomayoshi Hayashi, Hiroshi Ishii, Seiko Nakayama, Noriho Sakamoto, Sumako Yoshioka, Kanako Sugiyama, Mariko Mine, Yohei Mizuta, and Shigeru Kohno.
• Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki, Japan. kakugawa@jasmine.ocn.ne.jp
• Resp Res. 2005 Jan 1; 6: 57.

BackgroundHeat shock protein (HSP) 47, a collagen-specific molecular chaperone, is involved in the processing and/or secretion of procollagens, and its expression is increased in various fibrotic diseases. The aim of this study was to determine whether quantitative immunohistochemical evaluation of the expression levels of HSP47, type I procollagen and alpha-smooth muscle actin (SMA) allows the differentiation of idiopathic usual interstitial pneumonia (UIP) from UIP associated with collagen vascular disease (CVD) and idiopathic nonspecific interstitial pneumonia (NSIP).MethodsWe reviewed surgical lung biopsy specimens of 19 patients with idiopathic UIP, 7 with CVD-associated UIP and 16 with idiopathic NSIP and assigned a score for the expression of HSP47, type I procollagen and alpha-SMA in type II pneumocytes and/or lung fibroblasts (score 0 = no; 1 = weak; 2 = moderate; 3 = strong staining).ResultsThe expression level of HSP47 in type II pneumocytes of idiopathic UIP was significantly higher than in CVD-associated UIP and idiopathic NSIP. The expression of HSP47 in fibroblasts was significantly higher in idiopathic UIP and idiopathic NSIP than in CVD-associated UIP. The expression of type I procollagen in type II pneumocytes was significantly higher in idiopathic UIP than in idiopathic NSIP. The expression of type I procollagen in fibroblasts was not different in the three groups, while the expression of alpha-SMA in fibroblasts was significantly higher in idiopathic UIP than in idiopathic NSIP.ConclusionOur results suggest the existence of different fibrotic pathways among these groups involved in the expression of HSP47 and type I procollagen.

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