Mari Higashiyama

Possible role of coexpression of CD9 with membrane-anchored heparin-binding EGF-like growth factor and amphiregulin in cultured human keratinocyte growth.

CD9 is a protein with 4 transmembrane domains, and functions as a cell surface antigen. We have previously reported that CD9 functions as an up‐regulator of membrane‐anchored heparin‐binding EGF‐like growth factor (proHB‐EGF) activity, which is a potent mitogen as well as a soluble HB‐EGF. Anti‐CD9 antibodies can neutralize the juxtacrine activity of proHB‐EGF when both CD9 and proHB‐EGF are coexpressed. We demonstrated here: (1) the CD9 gene was transcribed and translated in the cultured human keratinocytes; (2) anti‐CD9 antibody inhibited the approximately 50% growth of human keratinocytes in culture; (3) CD9 was coprecipitated with proHB‐EGF and membrane‐anchored amphiregulin (proAR), and (4) the transient coexpression of CD9 with proHB‐EGF or proAR in mouse L cells up‐regulated their juxtacrine growth factor activities. These results suggest that CD9 would make a heterodimer and/or trimer complex with proHB‐EGF and proAR, and might cooperate with proHB‐EGF and proAR for human keratinocyte growth in a juxtacrine manner. J. Cell. Physiol. 171:291–298, 1997.

Activation of monocytes in vivo causes intracellular accumulation of lipoprotein-derived lipids and marked hypocholesterolemia—a possible pathogenesis of necrobiotic xanthogranuloma

Necrobiotic xanthogranuloma (NXG) is a rare histiocytic disease with generalized xanthomatosis. However, most cases with NXG are normolipidemic or hypolipidemic. The mechanism for the formation of xanthoma in NXG has not yet been clarified. We observed a case of NXG with severe hypocholesterolemia (total cholesterol: 1.69 mmol/l) and analyzed the function of monocytes in this case. Histological examinations by light microscopy revealed a large amount of lipid deposition in the patients freshly isolated monocytes. The patients monocytes showed a 3-fold increase in cholesteryl ester content and a 3-fold enhancement of acetyl low density lipoprotein (LDL) uptake compared with the control monocytes. However, no significant difference was noted in the expression of CD36 protein and the mRNA levels of scavenger receptor-class A (SR-A) between the monocytes of the patient and the control. The phagocytotic ability of the patients monocytes was enhanced 1.5-fold compared with that of the control monocytes. These findings suggest that the activated monocytes may have degraded the modified LDL via a pathway other than CD36 or SR-A, and accumulated a great amount of lipids in vivo. In conclusion, the present study has demonstrated a possible pathogenesis of NXG that the activation of monocytes in vivo may contribute to the intracellular accumulation of lipoprotein-derived lipids leading to non-inherited xanthomatosis and the marked hypocholesterolemia.

Herpetiform pemphigus showing reactivity with pemphigus vulgaris antigen (desmoglein 3)

We report a patient with herpetiform pemphigus(HP)who showed reactivity only with pemphigus vulgaris(PV)antigen but not with pemphigus foliaceus(PF)antigen. Direct and indirect immuno‐ fluorescence revealed keratinocyte cell surface staining in the lower layers of the epidermis, where desmoglein 3 (Dsg3) is expressed. Immunoblot analysis, using ethylenediamine tetra‐acetic acid‐ separated human epidermal extracts, revealed that the patients serum recognized only a 130‐kDa polypeptide which co‐migrated with Dsg3. By antigen‐specific immunoadsorption studies, using desmoglein 1 (Dsg1) and Dsg3 recombinant protein produced by baculovirus expression system, immunoreactivity of the patients serum was completely adsorbed by Dsg3 alone, but not by Dsg1. These results indicate that this HP patient produced only anti‐Dsg3 autoantibodies and no other autoantibodies against components of the keratinocyte cell surface. HP could be a variant of PV.in addition to PF, with unique clinical and histological features.

Analysis of antigens recognized by autoantibodies in herpes gestationis. Usefulness of immunoblotting using a fusion protein representing an extracellular domain of the 180 kD bullous pemphigoid antigen

Herpes gestationis (HG) is a rare pregnancy-associated disease. The aim of this study was to compare various immunohistochemical and immunobiochemical techniques with respect to their diagnostic sensitivity for HG. We studied 43 HG sera; only half of these reacted with the basement membrane zone (BMZ) with both indirect immunofluorescence (IF) and complement IF of normal human skin. 81% of the sera reacted with the epidermal side of 1 M NaCl-split skin. In general, titers of anti-BMZ antibodies in HG sera were lower than those in bullous pemphigoid (BP) sera. Immunoblot analysis of human epidermal extracts showed that 51% of HG sera recognized the 180 kD BP antigen (BP180) and 26% recognized the 230 kD BP antigen (BP230). We also studied the reactivity of HG sera with fusion proteins representing either the NC16a domain of human BP180 or the C-terminal region of mouse BP230. Whereas 79% of HG sera reacted with the BP180 fusion protein, only 5% recognized the BP230 fusion protein. Our results suggest that indirect IF of 1 M NaCl-split skin and immunoblotting of a fusion protein representing the BP180 NC16a domain are more sensitive techniques for the diagnosis of HG than conventional and complement IF or immunoblotting of crude epidermal extracts.

Involvement of insulin-like growth factor-I in psoriasis as a paracrine growth factor : dermal fibroblasts play a regulatory role in developing psoriatic lesions

Abstract To investigate the contribution of dermal fibroblasts to the development of psoriasis, we examined the expression of mRNA for insulin-like growth factor-I (IGF-I) and its regulator IGF-I binding proteins (IGFBPs) in psoriatic fibroblasts by RT-PCR. We also studied the effect of inflammatory cytokines including interferon gamma (IFN-γ), tumor necrosis factor alfa (TNF-α), and IFN-α on the expression of IGF-I and IGFBPs in the fibroblasts. Semiquantitative analysis revealed that IGF-I mRNA expression in psoriatic fibroblasts (PF) was significantly higher than in control fibroblasts (CF). However, no significant difference in IGF-I mRNA was shown between nonlesional psoriatic fibroblasts (NF) and CF. Treatment with IFN-α in vitro upregulated IGF-I mRNA in PF and in CF. TNF-α appeared to downregulate IGF-I mRNA in PF but had no effect on CF. IFN-γ did not show a significant effect on IGF-I mRNA levels in any type of fibroblast. IGFBP-3 mRNA was expressed equally in PF and CF, and was not affected by cytokines. The expression of IGFBP-5 mRNA in PF was downregulated by IFN-γ and TNF-α. Taken together, these results indicate that dermal fibroblasts may contribute to the epidermal hyperplasia of psoriasis by promoting keratinocyte proliferation through IGF-I, whose secretion could be modulated by inflammatory cytokines.

Detection of anti-desmocollins I and II autoantibodies in two cases of Hallopeau type pemphigus vegetans by immunoblot analysis

Pemphigus foliaceus (PF) sera react with a 150 kDa antigen, desmoglein (DG), while pemphigus vulgaris (PV) sera react with a 130 kDa PV antigen. Recent molecular cloning studies have revealed that both DG and PV antigen are members of the cadherin family of cell adhesion molecules and that PV antigen shows very high homology to DG. We have recently noticed that other desmosoal cadherin molecules, desmocollins I and II (DC I/II), are also recognized by some pemphigus antibodies. In the present study we report two cases of Hallopeau type pemphigus vegetans. Immunoblot study revealed that the sera of these cases reacted not only with the PV antigen but also with both DG (PF antigen) and DC I/II. Although the significance of these findings is not known at present, further studies for the antigen profile for more Hallopeau type pemphigus vegetans patients may unravel the pathogenesis of this rare type of pemphigus.

Growth‐inhibitory effects of 1,25‐dihydroxyvitamin D3 on normal and psoriatic keratinocytes

The effects of 1,25‐dihydroxyvitamin D3 (1,25(OH)2D3) on the growth and DNA synthesis of cultured human keratinocytes obtained from involved and uninvolved psoriatic epidermis and normal epidermis were studied. Treatment with 10‐8m and 10‐7m of 1,25(OH)2D3 inhibited cell growth as follows: 58.5±19.3% and 21.3±13.6% in normal keratinocytes (n=6); 43.8±22.8% and 17.8±12.3% in psoriatic uninvolved keratinocytes (n=4); 51.7±18.2% and 13.2±6.4% in psoriatic involved keratinocytes (n=6). Inhibition was virtually complete at 10‐6m. DNA synthesis was also inhibited by 10‐8m, 10‐7m and 10‐6m of 1,25(OH)2D3 as follows: 70.0±8.3%, 59.0±6.8% and 16.7±4.0%, respectively, in normal keratinocytes (n=3); 78.5±13.5%, 51.5±25.5% and 24.5±21.5%, respectively, in psoriatic uninvolved keratinocytes (n=2); and 69.3±14.5%, 41.3±19.1% and 14.8±11.2%, respectively, in psoriatic involved keratinocytes (n=4). These results indicate that 1,25(OH)2D3 functions as a growth inhibitor for cultured human keratinocytes derived from both normal and psoriatic skin.

A case of giant axonal neuropathy showing focal aggregation and hypophosphorylation of intermediate filaments

We report here the clinicopathological features of a typical case of giant axonal neuropathy (GAN). Scanning electron microscopy of the hair of this case revealed an extraordinarily irregular cuticle. Focal accumulation of intermediate filaments in axons, Schwann cells, muscle fibers and skin fibroblasts were also found under an electron microscopy. When examined immunocytochemically, muscle fibers exhibited local disruption of the filamentous network in the subsarcolemmal space and in the central cytoplasm accompanied by focal accumulation of desmin. The intracellular network of vimentin was also disrupted, exhibiting global accumulation in some of the cultured skin fibroblasts. Decreased interneurofilament spacing was found in enlarged axons, suggesting the presence of hypophosphorylation of neurofilaments in this patient. These findings suggest general disorganization, abnormal distribution and possible defective phosphorylation of intermediate filaments in GAN.

Increased Production of Transforming Growth Factor-α in Psoriatic Epidermis

To elucidate the involvement of transforming growth factor‐α (TGF‐α) in the pathogenesis of psoriasis, we measured TGF‐α levels in the extracts from six normal epidermis and four psoriatic involved epidermis samples by enzyme‐linked sorbent assay using monoclonal antibody specific for TGF‐α. The amount of TGF‐α in the extracts of normal epidermis was 1.45 ± 1.06 ng/g of wet tissue, while the amount in psoriatic involved epidermis was 6.71 ± 0.75 ng/g of wet tissue. The TGF‐α level in psoriatic involved epidermis was thus 4.62 fold higher than that of normal epidermis (P<0.001). TGF‐α binds to epidermal growth factor receptors and functions as an autocrine growth factor for epidermal keratinocytes. Therefore, the increased levels of TGF‐α may be involved in the induction or the maintenance of hyperproliferation of psoriatic epidermal keratinocytes.

Three cases of chemotherapy-induced acral erythema.

Three cases of chemotherapy‐induced acral erythema are reported. All the patients had received cyclophosphamide, vincristine, adriamycin, prednisolone, and granulocyte‐colony stimulating factor (G‐CSF) for the treatment of leukemia or malignant lymphoma. From 35 to 45 days after the start of chemotherapy, painful erythematous lesions developed on their palms, soles, fingers, and toes, resulting in blister formation and desquamation. The recent higher incidence of chemotherapy‐induced acral erythema may be correlated with the popularity of G‐CSF, which allows the use of higher doses of chemotherapeutic drugs.