Background/Purpose:

Scleroderma or systemic sclerosis (SSc) is characterized by the fibrosis of skin and visceral organs, especially the uncontrolled fibrosis of multiple organs. Collagen is a major extracellular matrix (ECM) protein that deposited in the fibrotic organs. Heat shock protein 47 (HSP47) has been identified as a collagen-specific chaperon, and plays an important role in the development of fibrosis. Our previous study demonstrated that HSP47 was significantly up-regulated in the skin of dermal sclerosis mice induced by bleomycin. The aim of the present study is to investigate the role of HSP47 in the pathogenesis of scleroderma.

Methods:

For in vivo studies, C57BL/6 female mice of 6-8 weeks (n = 5 for each treatment) were injected with bleomycin subcutaneously into the same site of the shaved upper back daily for 3 weeks. The mRNA and protein level of HSP47 in the lesion skins from the mouse model was assessed by real-time PCR and western blot. In clinical study, skin biopsies and fibroblasts, peripheral blood mononuclear cells (PBMC) and plasma of SSc patients were obtained to study the role of HSP47 during the pathogenesis of SSc. Immunohistochemical staining was performed to identify the localization of HSP47 in the skin of SSc patients, real-time PCR and western blot were conducted to respectively test the gene and protein expression levels of HSP47 in the skin fibroblasts, and ELISA was used to detect the protein level of HSP47 in the plasma of SSc patients. For in vitro study, silencing and over-expression of HSP47 in NIH/3T3 fibroblast cells were performed using HSP47 siRNA and HSP47 expression plasmid respectively to investigate the effect of HSP47 on collagen production.

Results:

For in vivo study, HSP47 was significantly up-regulated in the skin lesion of the mice treated by bleomycin. Meanwhile, the expression of α-SMA increased in the skin lesion of the mice in response to bleomycin. In clinical study, the level of HSP47 increased in the fibroblasts cultured from SSc patients’ skin, the number of HSP47 positive cells increased in the skin of SSc patients, and the localization of HSP47-positive cells were observed in accordance with the α-SMA-positive cells. Additionally, the protein level of HSP47 in the plasma and the mRNA level of HSP47 in the peripheral blood mononuclear cells were both elevated in the SSc samples. In vitrostudy found that over-expression of HSP47 in the fibroblasts increased the level of collagen, whereas knockdown of HSP47 gene decreased its expression.

Conclusion: The production of collagen is affected by HSP47, and HSP47 might be involved in the pathogenesis of scleroderma. Further investigations may be necessary to test this collagen chaperone as an important therapeutic approach.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/involvement-of-collagen-binding-heat-shock-protein-47-in-the-scleroderma-associated-fibrosis/