miR-29a at the SSD stage, but maintained by other factors in SSc patients. Table 1a shows the association of serum miR-29a levels with the clinical features in SSc patients. Considering that collagen expression in SSc patients is up-regulated as described above, we regarded reduction of miR-29a levels as the meaningful change. We found that SSc patients with reduced miR-29a levels had significantly higher right ventricular systolic pressure by Doppler echocardiography than those with normal levels. Though the cause of pulmonary hypertension in SSc is still uncertain, our results suggested that miR-29a also takes part in the pathogenesis of pulmonary hypertension. On the other hand, as shown in Table 1b, clinical features of each SSD patient were not correlated with the levels of miR-29a. Taken together, serum miR-29a levels is not likely to be a specific marker for clinical manifestations of SSD, but the miRNA may play an important role in the pathogenesis of this disease. The concept of SSD has been proposed by Maricq et al. originally to unify typical SSc, early forms of SSc and closely related disorders including mixed connective tissue disease (MCTD) [8,9]. Thereafter, Ihn et al. established a new diagnostic method using a points system to distinguish patients with SSD from those with early SSc [10]. Although the point system has not been accepted in the world wide basis, because progressive fibrosis of SSc is often irreversible, at least clinically, there is an urgent need to develop new strategies to diagnose patients as early as possible and follow-up carefully. For that purpose, the concept of SSD should be further understood and characterized. Our study is the first to examine serum miRNA levels using sera from SSD as well as SSc, and is shedding new light on the definition of SSD. To note, it may be difficult to distinguish early stage SSc from SSD, because skin sclerosis is sometimes not apparent in early SSc, especially in lcSSc. Serum levels of miR-29a levels may be useful for the differentiation of SSc from SSD. As the limitation of this study, we could not collect large number of SSD patients because of the rarity of this condition. However, our approach may be effective to clarify the property of SSD. Larger studies are needed in the future. Acknowledgements This study was supported in part by a grant for scientific research from the Japanese Ministry of Education, Science, Sports and Culture, by project research on intractable diseases from the Japanese Ministry of Health, Labour and Welfare. References [1] Korn JH. Immunologic aspects of scleroderma. Curr Opin Rheumatol 1989;1(4):479–84. [2] Mauch C, Krieg T. Fibroblast-matrix interactions and their role in the patho- genesis of fibrosis. Rheum Dis Clin North Am 1990;16(1):93–107. [3] Jelaska A, Arakawa M, Broketa G, Korn JH. Heterogeneity of collagen synthesis in normal and systemic sclerosis skin fibroblasts: increased proportion of high collagen-producing cells in systemic sclerosis fibroblasts. Arthritis Rheum 1996;39(8):1338–46. [4] LeRoy EC. Increased collagen synthesis by scleroderma skin fibroblasts in vitro: a possible defect in the regulation or activation of the scleroderma fibroblast. J Clin Invest 1974;54(4):880–9. [5] Kroh EM, Parkin RK, Mitchell PS, Tewari M. Analysis of circulating microRNA biomarkers in plasma and serum using quantitative reverse transcription-PCR (qRT-PCR). Methods 2010;50(4):298–301. [6] Lewis BP, Burge CB, Bartel DP. Conserved seed pairing, often flanked by adenosines, indicates that thousands of human genes are microRNA targets. Cell 2005;120(1):15–20. [7] Ihn H, Sato S, Fujimoto M, Kikuchi K, Igarashi A, Soma Y, et al. Measurement of anticardiolipin antibodies by ELISA using b2-glycoprotein I (b 2-GPI) in systemic sclerosis. Clin Exp Immunol 1996;105(3):475–9. [8] Maricq HR, McGregor AR, Diat F, Smith EA, Maxwell DB, LeRoy EC, et al. Major clinical diagnoses found among patients with Raynaud phenomenon from the general population. J Rheumatol 1990;17(9):1171–6. [9] Maricq HR, Weinrich MC, Keil JE, Smith EA, Harper FE, Nussbaum AI, et al. Prevalence of scleroderma spectrum disorders in the general population of South Carolina. Arthritis Rheum 1989;32(8):998–1006. [10] Ihn H, Sato S, Tamaki T, Soma Y, Tsuchida T, Ishibashi Y, et al. Clinical evaluation of scleroderma spectrum disorders using a points system. Arch Dermatol Res 1992;284(7):391–5. Yoshio Kawashita Masatoshi Jinnin* Takamitsu Makino Ikko Kajihara Katunari Makino Noritoshi Honda Shinich Masuguchi Satoshi Fukushima Yuji Inoue Hironobu Ihn Department of Dermatology and Plastic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Japan *Corresponding author. Tel.: +81 96 373 5233; fax: +81 96 373 5235 E-mail address: jinjin1011@hotmail.com mjin@kumamoto-u.ac.jp 14 October 2010 doi:10.1016/j.jdermsci.2010.11.007 Letter to the Editor Differential hyaluronan homeostasis and expression of proteoglycans in juvenile and adult human skin Cutaneous ageing is a complex biological process affecting all skin components. It consists of two independent, clinically and biologically, distinct processes. The first is intrinsic or innate ageing, which affects the skin in the same pattern as it affects all internal organs. The second is extrinsic ageing, which is the result of exposure to external factors, mainly ultraviolet (UV) irradia- tion [1]. Extracellular matrix molecules are highly implicated in the ageing process and exhibit specific alterations in extrinsic and intrinsic skin ageing [2]. Among them, hyaluronic acid (HA) is of high importance since it has the unique capacity of binding water, thus providing viscosity and hydration to the dermis. In photo- ageing process, HA homeostasis shows specific alterations since in photo-aged skin HA of reduced size is elevated and exhibits abnormal deposition [3]. In this study, we have tried to elucidate alterations in HA homeostasis and proteoglycan expression associated with intrinsic skin ageing. We employed juvenile skin tissue specimens (n = 10, mean age 5 years, 4 mm punch biopsies) collected from foreskin of children undergoing surgery for phimosis. Adult photo-protected skin tissue specimens (n = 16, mean age 72 years, 4 mm punch biopsies) were collected from the area behind the ear lobe. Total glycosaminoglycans were isolated and purified from skin tissue specimens, as previously described [3]. Aliquots of total glycosa- minoglycans were assayed for HA content by ELISA. Gene Letters to the Editor / Journal of Dermatological Science 61 (2011) 60–81 69