Japanese Society for Psoriasis Research

Hajime Iizuka, M.D.

Asahikawa Medical College

Midorigaoka-Higashi 2-1-1

Asahikawa

078-8510 Japan

The Japanese Society for Psoriasis Research was founded in 1986; the founding chairman was Prof. Yoshio Nakamizo (Kyushu University). Following chairmen were Prof. Muneo Ohkido (Tokai University), Prof. Akira Ohkawara (Hokkaido University), Prof. Tadashi Tezuka (Kinki University), Prof. Fumio Kaneko (Fukushima University), and Prof. Hajime Iizuka (Asahikawa Medical College). The society was founded in order to exchange information on psoriasis research and newly-available treatment options. Since then the society has been developed with increasing active members. The annual academic meeting is held in various parts of Japan, and is the most active meeting exchanging the clinical and basic information of Japanese psoriasis study.

Although the incidence of psoriasis in Japan is much lower (around 0.1% of general population) than in Caucasians, Japan has long been one of the most active places for psoriasis research. This is best exemplified by the original application of topical PUVA treatment by Prof. late Nobuyuki Mizuno (Nagoya City University) in early the 1970s, and by the clinical use of vitamin D3 by Prof. Kunihiko Yoshikawa (Osaka University). HLA analyses have been performed by Prof. Muneo Ohkido, Prof. Akira Ozawa (Tokai University), Prof. Masahiko Muto (Yamaguchi University), and Prof. Hidemi Nakagawa (Tokyo Jikei University). Furthermore, Prof. Hachiro Tagami (Tohoku University) originally demonstrated the involvement of complement activation, which was followed by studies of Prof. Tadashi Terui (Nihon University). Recently Prof. Shigetoshi Sano (Kochi University) demonstrated the involvement of STAT3 in the pathophysiology of psoriasis.

In Japan, the inhabitants are covered by the government health care system, and therefore, each specific treatment should be approved by the government (Ministry of Health, Labour and Welfare). So far no biologicals (adalimumab, infliximab, ustekinumab) are approved for psoriasis in Japan; however, the remarkable clinical response of these drugs for chronic inflammatory disorders such as rheumatoid arthritis and Crohn’s disease initiated numerous activities around psoriasis, including nationwide clinical trials. We are expecting the approval by the government and the provisional guideline for the use of biologicals in psoriasis to be available soon. In this occasion I will discuss about 4 topics, which are :

1. Psoriasis Patients Networks
2. Japan Psoriasis Registry
3. Guidelines for psoriasis (PUVA, ciclosporin and generalized pustular psoriasis)
4. Usual Treatment of Psoriasis in Japan

1. Psoriasis patient networks

Psoriasis patient networks were founded to improve the quality of life of psoriasis patients in Japan. Because of the relatively low incidence of psoriasis, the patient network did not exist officially until 1992, when the first network system was founded in Sapporo, Hokkaido. This was supported by Prof. Akira Ohkawara (Hokkaido University) and Dr. Hitoshi Kobayashi (Sapporo). Since then many regional patient networks were founded to exchange information about treatment and care on psoriasis. Regional expert dermatologists cooperate with the network. The meeting of the patients circle is held at the same place just after the annual meeting of Japanese Society for Psoriasis Research.

The psoriasis patients network

2. Japan Psoriasis Registry

Since 1986, the Japanese Society for Psoriasis Research has been registering psoriasis patients in Japan, and this is the most reliable epidemiological data. Each year newly registered patients are summarized at the annual meeting. In 2006 (data of 2007 will appear soon) the total Japanese psoriasis patients raise up to 38,078 cases, including 25,154 male and 12,925 female cases. Each year new cases are registered – 1,700-2,000 cases, suggesting that the incidence of psoriasis in Japan would be around 0.1-0.2% of population (in other words 100,000 – 150,000 cases). Among them, psoriasis vulgaris (nummular type psoriasis) represents 90% of cases, psoriasis arthropathica iaround 4%, followed by guttate type psoriasis (3%),　psoriatic erythroderma (1%), and generalized pustular psoriasis (1%). The incidence of psoriasis arthropathica in Japan (4%) is apparently lower than in Caucasians, but the figure might be underestimated, because once the patient is registered as psoriasis vulgaris, he/she would not be re-registered as psoriasis arthropathica even after they develop typical arthropathy. Also noteworthy is the finding that male/female ratio is around 2:1 in Japan. This has been appreciated since the first registration and each year the male female ratio of newly registered patients is also 2:1.

3. Guidelines for psoriasis

General guidelines for psoriasis treatment are not available in Japan. Specific guidelines for PUVA and ciclosporin treatments are available. The guidelines for PUVA treatment were published in 2000 by Prof. Kunihiko Yoshikawa et al. under the auspice of the Japanese Society for Psoriasis Research (Chairman: Prof. Akira Ohkawara). These cover systemic, topical PUVA and bath PUVA treatments for Japanese psoriasis populations. The guidelines for narrowband UVB for Japanese are not available at this point in time.

The original guidelines for the use of cicrosporin were proposed by Prof. Yasumasa Ishibashi (Tokyo University) in 1992. These were revised by Dr. Shotaro Harada in 2000, when cicrosporin MEPC (microemulsion preconcentrate) formulation was available in Japan, and then re-revised by Prof. Hidemi Nakagawa et al. in 2004. These PUVA and cicrosporin guidelines are well appreciated because of the efficacious and safe use of these treatments.

Recently, the diagnostic and therapeutic guidelines for generalized pustular psoriasis (GPP) were proposed by Prof. Keishi Iwatsuki (Okayama University) et al. in 2008. These iare the ‘provisional’ guidelines made by the members of the research group of the Ministry of Health, Labour and Welfare in Japan (project leader: Prof. Yasuo Kitajima (Gifu University)). These GPP guidelines are also well appreciated and are undergoing the review process by the expert dermatologists.

4. Usual Treatment of Psoriasis in Japan

In this section only the government-approved treatments covered by the national insurance system are described. (Methotrexate is not officially approved for psoriasis in Japan). The basic treatment for psoriasis is topical therapeutics (various corticosteroids and active vitamin D3). Three active vitamin D3 topical medications are available: tacalcitol, calcipotriol, and maxacalcitol. The topical treatment may be combined with phototherapy (topical PUVA therapy and narrowband UVB therapy). Topical PUVA therapy is much popular than systemic PUVA therapy in Japan, since the original report of topical PUVA by Prof. Nobuyuki Mizuno. Bath PUVA therapy may also be used. The PUVA treatments are performed under the guideline of PUVA by Yoshikawa et al (see above). Narrowband UVB is very popular now because of its simplicity. Systemic retinoid (etretinate) is a relatively weak treatment and so it is combined with topical treatments or with PUVA treatment. Etretinate is very effective for generalized pustular psoriasis. Ciclosporin is used for severe psoriasis cases under the revised guideline by Nakagawa et al (see above). No biologicals for psoriasis are available in Japan at this point in time (Oct. 2008).

Although the incidence of psoriasis is much lower than in Caucasians, the number of cases is steadily increasing in Japan. We believe the Japanese Society for Psoriasis Research should join with International Psoriasis Network so as to exchange the critical and essential information on treatment and care of this chronic inflammatory skin disease, psoriasis.