Tomoyasu Hattori

Identification of 9-hydroxyoctadecadienoic acid and other oxidized free fatty acids as ligands of the G protein-coupled receptor G2A.

G2A is a G protein-coupled receptor that is predominantly expressed in lymphoid tissues and macrophages. G2A can be induced by diverse stimuli to cause cell cycle arrest in the G2/M phase in pro-B and T cells. G2A is also expressed in macrophages within atherosclerotic lesions, suggesting G2A involvement in atherosclerosis. Recently, G2A was discovered to possess proton-sensing ability. In this paper, we report another function of G2A, that is, as a receptor for 9-hydroxyoctadecadienoic acid (9-HODE) and other oxidized free fatty acids. G2A, expressed in CHO-K1 or HEK293 cells, showed 9-HODE-induced intracellular calcium mobilization, inositol phosphate accumulation, inhibition of cAMP accumulation, [35S]guanosine 5′-3-O-(thio)triphosphate binding, and MAP kinase activation. Furthermore, G2A was activated by various oxidized derivatives of linoleic and arachidonic acids, but it was weakly activated by cholesteryl-9-HODE. Oxidized phosphatidylcholine (1-palmitoyl-2-linoleoyl) when hydrolyzed with phospholipase A2 also evoked intracellular calcium mobilization in G2A-expressing cells. These results indicate that G2A is activated by oxidized free fatty acids produced by oxidation and subsequent hydrolysis of phosphatidylcholine or cholesteryl linoleate. Thus, G2A might have a biological role in diverse pathological conditions including atherosclerosis.

Global DNA hypomethylation and hypoxia‐induced expression of the ten eleven translocation (TET) family, TET1, in scleroderma fibroblasts

The precise mechanisms of tissue fibrosis have not yet been elucidated in systemic sclerosis (SSc). However, studies of the regulation of DNA methylation, the most widely studied epigenetic mechanism, have confirmed the involvement of the TET family proteins, recently identified DNA demethylases, in the pathogenesis of SSc. The mRNA levels of TET family members were compared in normal and SSc fibroblasts. The effects of hypoxia and siRNA specific to HIF‐1α on TET expression were also examined. Global methylation status was analysed by LUMA. The presence of 5‐hydroxymethylcytosine (5hmC) in SSc was examined by immunohistochemistry. The level of TET1 mRNA in SSc fibroblasts was elevated by 1.68 fold compared with that of normal fibroblasts, but the expression levels of TET2 and TET3 were comparable between both cell types. The expression levels of DNMT1 and DNMT3B mRNA have a tendency to elevate in SSc fibroblasts. Among TET family members, the expression of TET1 was exclusively induced by hypoxia via HIF‐1α‐independent pathways in SSc fibroblasts, but not in normal fibroblasts. The methylation level was decreased in SSc fibroblasts relative to normal fibroblasts, and 5hmC was present in dermal fibroblasts of skin sections from patients with SSc. TET1 expression in SSc fibroblasts was abnormally regulated in the hypoxic environment and accompanied by global DNA hypomethylation, suggesting the involvement of aberrant DNA methylation in the pathogenesis of SSc.

The prevalence of Merkel cell polyomavirus in Japanese patients with Merkel cell carcinoma

BACKGROUND A novel polyomavirus, the Merkel cell polyomavirus (MCPyV) has been implicated in the pathogenesis of Merkel cell carcinoma (MCC); however, the prevalence of MCPyV in Japan has not been extensively investigated. OBJECTIVE To clarify the prevalence of MCPyV in Japanese patients with MCC. METHODS MCPyV DNA was examined by polymerase chain reaction (PCR) in formalin-fixed paraffin-embedded (FFPE) or frozen tissue samples from 26 patients with MCC diagnosed in four medical centers in Japan. Immunohistochemistry was simultaneously performed using a monoclonal antibody against the viral large T (LT) antigen. FFPE samples from basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) were also analyzed as controls. RESULTS Twenty-three out of 26 cases (88.5%) were positive for MCPyV DNA by PCR. The amplified products harbored 4 patterns of mutations. Phylogenetic analysis demonstrated that one of our strains was closely related to the other Japanese strains previously reported. The LT antigen was expressed in various degrees in 20 of 26 cases (76.9%) by immunohistochemistry. Histological type had little relation to CM2B4 positivity, whereas 3 of 5 trabecular-type tumors showed no staining. The immunoreactivity for CM2B4 did not correlate with the relative viral DNA load. In BCC and SCC, the LT antigen was immunohistochemically positive, but MCPyV DNA was not detected by PCR. The cells around some MCC and non-MCC tumors were stained with CM2B4 with a distribution similar to CD20- and CD45RO- (especially CD8-) positive lymphocytes. CONCLUSION MCPyV was highly positive in Japanese patients with MCC. It is of note that the positive rate differs depending upon the detection method.

Isolated cutaneous manifestation of IgG4-related disease

Aims The cutaneous manifestation of IgG4-related disease has rarely been reported. The aim of this study is to identify and describe the cutaneous manifestations associated with IgG4-positive plasma cell infiltration in the skin. Methods The authors investigated two cases of IgG4-related disease with solitary skin lesions and compared the immunohistochemical characteristics of infiltrating cells among IgG4-related disease, Kimuras disease and cutaneous pseudolymphoma. Results IgG4-related disease manifested as an indurated plaque on the anterior chest in one case and a nodule on the toe in the other case. Histopathologically, skin lesions of IgG4-related disease showed a dense, mixed-cell infiltrate containing lymphocytes, plasma cells and eosinophils along with fibrosis. Plasma cells stained positively with anti-IgG and anti-IgG4 antibodies, and the ratio of IgG4+/IgG+ cells was more than 50%. Serum levels of IgG and IgG4 were not elevated and no lesions were found in other organs. Skin samples taken from Kimuras disease showed histopathological features similar to those of IgG4-related disease. The proportion of IgG4+/IgG+ was high in Kimuras disease, but not in cutaneous pseudolymphoma. Conclusions The solitary skin lesions of IgG4-related disease were similar histologically and immunohistochemically to the skin lesions of Kimuras disease. The concept of IgG4-related disease may help clarify the pathomechanism of diseases of unknown aetiology that possess features of IgG4-related disease.

Sp1 Is a Co-activator with Ets-1, and Net Is an Important Repressor of the Transcription of CTP:Phosphocholine Cytidylyltransferase α

Phosphatidylcholine biosynthesis via the CDP-choline pathway is primarily regulated by CTP:phosphocholine cytidylyltransferase (CT) encoded by the Pcyt1a and Pcyt1b genes. Previously, we identified an Ets-1-binding site located at -49/-47 in the promoter of Pcyt1a as an important transcriptional element involved in basal CTα transcription (Sugimoto, H., Sugimoto, S., Tatei, K., Obinata, H., Bakovic, M., Izumi, T., and Vance, D. E. (2003) J. Biol. Chem. 278, 19716-19722). In this study, we determined whether or not there were other important elements and binding proteins for basal CTα transcription in the Pcyt1a promoter, and if other Ets family proteins bind to the Ets-1-binding site. The results indicate the formation of a ternary complex with Ets-1 binding at -49/-47 and Sp1 binding at -58/-54 of the Pcyt1a promoter that is important for activating CTα transcription. When nuclear extracts of COS-7 cells expressing various Ets family repressors were incubated with DNA probes, binding of Net to the probes was observed. Net dose-dependently depressed the promoter-luciferase activity by 98%, even when co-expressed with Ets-1. RNA interference targeting Net caused an increase of endogenous CTα mRNA. After synchronizing the cell cycle in NIH3T3 cells, CTα mRNA increased at the S-M phase corresponding to an increase of Ets-1 mRNA and a decrease of Net mRNA. These results indicated that Net is an important endogenous repressor for CTα transcription.

Unilateral Generalized Morphea in Childhood

We report a 6‐year‐old boy with unilateral generalized morphea distributing on the right side of his lower leg, trunk, and upper arm. A skin biopsy from the right thigh showed accumulation of thick collagen bundles extending from the middle dermis to the subcutaneous fat tissue. The levels of antinuclear antibodies, rheumatoid factor, and anti single‐stranded DNA antibody were elevated. No severe deformity or functional disabilities were noted. With topical corticosteroid therapy, the sclerotic skin became gradually softer, and no progression of sclerosis has been noted for one year.

No association of atherosclerosis with digital ulcers in Japanese patients with systemic sclerosis: Evaluation of carotid intima-media thickness and plaque characteristics

Patients with systemic sclerosis (SSc) usually develop Raynauds phenomenon, persistent digital ischemia and sometimes develop digital ulcers (DU). Several studies have reported an association of carotid artery atherosclerosis with SSc by evaluating carotid intima‐media thickness (IMT) in SSc patients. However, none of those studies analyzed the association between DU and carotid artery atherosclerosis in SSc patients. We examined the association of carotid artery atherosclerosis with digital ulcers by comparing SSc patients with (n = 48, 29.5%) and without (n = 206, 70.5%) DU. The demographic and clinical features of the SSc patients showed that young age, male sex, anti‐topoisomerase I antibody positivity, severe skin sclerosis, interstitial lung disease complication and cardiac involvements were significantly prevalent in patients with DU. In addition, diffuse cutaneous type, anti‐RNA polymerase III antibody positivity and severe skin sclerosis are more frequent in SSc patients with DU at the extensor surface of joints than SSc patients with DU at the digital tip. There were no differences in serum lipid level, carotid IMT or plaque score between SSc patients with and without DU, suggesting that atherosclerotic changes are not primarily involved in the development of DU.

A Case of Hypersensitivity Syndrome due to Phenytoin

We report a 30‐year‐old female with hypersensitivity syndrome (HS) due to phenytoin. Her disease course was typical with elevation of the antibody titer for human herpes virus 6. Three courses of methylpredonisolone pulse therapy were required to control the disease activity. Since the pathogenic mechanism and treatments for HS have not been established, further clinical analyses are warranted.

Clinical follow‐up study of adult‐onset Still’s disease

Eighteen patients with adult‐onset Still’s disease have been followed up for 3–22 years in our department. Initial manifestations were fever with skin rash in 14 patients, fever, skin rash and sore throat in two, skin rash in one and arthralgia in one. During the follow‐up period, typical skin rash was seen in all patients, of them five patients (29%) revealed atypical skin rash simultaneously. Atypical rash included persistent erythema with pigmentation in two, persistent plaques and papules with linear erythema in two and edema of the eyelids mimicking dermatomyositis in one. Persistent papules and plaques revealed histologically characteristic features, such as dyskeratotic keratinocyte and liquefaction degeneration as well as a sparse superficial dermal infiltrate containing scattered neutrophils. In patients of chronic articular type and polycyclic systemic type, atypical skin rash, lymphadenopathy and hyperferritinemia were noted to be significantly higher than those of monocyclic type. These factors might be prognostic factors of adult‐onset Still’s disease in our study.

Leukemia cutis in a patient with acute monocytic leukemia presenting as unique facial erythema.

A 67‐year‐old woman was referred to our department with a 1‐month history of facial exanthemas. She had been diagnosed as having acute monocytic leukemia (French–American–British classification, M5b) based on the histological findings of bone marrow. Physical examination revealed diffuse edematous erythema on her cheeks, eyelids and glabella with scattered reddish papules. Histological examination demonstrated dense infiltration of atypical mononuclear cells in the dermis. Specific cutaneous lesions could occur in acute monocytic leukemia more frequently than in other types of leukemia, but rarely show symmetrical edematous erythema limited to the face.