Kowichi Jimbow

Increased sensitivity of melanocytes to oxidative stress and abnormal expression of tyrosinase-related protein in vitiligo.

Background u2003Vitiligo is a depigmenting disease of the skin, which may derive from programmed melanocyte death or destruction due to inherent sensitivity to oxidative stress arising from either toxic intermediates of melanin, a melanocyte‐specific protein, or other sources. Tyrosinase‐related protein (TRP) ‐1 has been shown to be involved not only in melanin biosynthesis but also in the prevention of premature melanocyte death in animals.

Basic fibroblast growth factor reduces scar formation in acute incisional wounds

In order to identify a means to reduce scar formation of the skin after incision, this study examined the effect of local administration of basic fibroblast growth factor (bFGF) in humans. bFGF was administered to a sutured wound immediately after an operation. The drug was injected once into the dermis of the margins of wounds using a 27G needle or rinsing after performing dermostitches. The lengths of the treated wounds varied from 1 to 32u2003cm, and the subjects were 2–86 years old. Sutured wounds after excision of skin tumors from the face, trunk, and limbs and sutured wounds such as those at the donor sites of full‐thickness skin grafts were treated with low‐dose bFGF injections (0.1u2003μg/cm wound; Group 2), high‐dose bFGF injections (1u2003μg/cm wound; Group 3), and rinsed with high‐dose bFGF (1u2003μg/cm wound; Group 4). No patient treated with bFGF had hypertrophic scars, while some patients had hypertrophic or very wide scars in the control group (Group 1), and the ratios of minimum scarring of Group 2 (u2003p<0.001), Group 3 (u2003p<0.0001), and Group 4 (u2003p<0.0001) were statistically significantly higher than those of Group 1. Postoperative administration of bFGF inhibited hypertrophic scarring and widening of remaining scars without any serious side effects.

Basic fibroblast growth factor promotes apoptosis and suppresses granulation tissue formation in acute incisional wounds

Cytokines are thought to play an important role in cellular loss and apoptosis during the repair of granulation tissue. In order to investigate the role of apoptosis following the administration of basic fibroblast growth factor (bFGF) to a wound, the present study examined the relationship between the degree of granulation tissue formation and the level of apoptosis in rat skin incisional wounds, following treatment with an intradermal injection of bFGF (0.1 µg and 1 µg per cm of wound). Histological assessment of the width of the wound tissue showed that the degree of granulation tissue in the 1 µg‐bFGF‐treated group had increased by day 7, but then subsequently diminished by days 14 and 28. The TUNEL index increased rapidly from day 1, peaking on day 7, with the index being higher in the 1 µg‐bFGF‐treated group on days 4, 7, and 14, when compared with a control group. In parallel with a marked increase in the TUNEL index over the first 14 days, the number of cells positive for vimentin and CD3 in the 1 µg‐bFGF‐treated wounds had decreased by day 14. The number of PCNA‐positive cells, an indicator of cell proliferation, peaked on day 4 in the bFGF‐treated wounds and then declined rapidly. On the basis of these results, it is suggested that the suppression of granulation tissue formation in bFGF‐treated wounds is mainly due to an early and persistent increase in apoptosis in the granulation tissue cells. The expression of both transforming growth factor (TGF)‐β1 and bFGF was also elevated in the bFGF‐treated wounds on days 4 and 7, suggesting that fibroblast apoptosis was induced by bFGF treatment. Unexpectedly, on day 28, the wound breaking strength was not reduced in the bFGF‐treated wounds. These results indicate that apoptosis regulation following bFGF administration to an incisional wound may lead effectively to granulation tissue formation and promote a scar‐less repair process. Copyright

Basic fibroblast growth factor in an artificial dermis promotes apoptosis and inhibits expression of α‐smooth muscle actin, leading to reduction of wound contraction

To clarify the mechanisms underlying declines in wound contraction caused by basic fibroblast growth factor (bFGF) and the role of autologous fibroblasts in modulating wound healing, we have examined the expression of α‐smooth muscle actin (α‐SMA) and apoptosis in a model of wound healing using collagen sponges with and without bFGF (1u2003μg) and/or fibroblasts (1 × 106u2003cells/cm2) applied to experimentally produced full‐thickness skin wounds in rats (n=10 for each group). At 7 days postoperatively, wounds filled with a fibroblast‐seeded collagen sponge (fibroblast‐seeded group) displayed a greater area of collagen sponge and a smaller area of fibroblasts compared with control wounds filled with collagen sponge alone (control group). Therefore, seeding of fibroblasts in the dermal substitute might retard degradation of the collagen sponge, inhibiting fibroblast infiltration into the substitute. By day 14, wounds filled with bFGF‐treated collagen sponge without fibroblast seeding (bFGF group) displayed decreased α‐SMA expression and significantly increased apoptosis compared with other wounds. Double staining revealed that apoptosis in α‐SMA‐positive fibroblastic cells was significantly increased in the bFGF group, suggesting that bFGF treatment is a potent stimulator of myofibroblast apoptosis. Furthermore, morphometric analysis demonstrated the significant decrease in the level of wound contraction and the degree of mature collagen bundle formation in the bFGF group by day 42. The bFGF group also showed increased bFGF expression in macrophages by day 28. These results suggest that bFGF administration to an artificial dermis promotes apoptosis of α‐SMA‐positive fibroblastic cells and inhibits α‐SMA expression in the treated wound, thus reducing wound contraction.

4‐S‐Cysteaminylphenol‐loaded magnetite cationic liposomes for combination therapy of hyperthermia with chemotherapy against malignant melanoma

Tyrosine analogs are good candidates for developing melanoma chemotherapies because melanogenesis is inherently toxic and expressed uniquely in melanocytic cells. The sulfur homolog of tyrosine, 4‐S‐cysteaminylphenol (4‐S‐CAP), was shown to be a substrate of melanoma tyrosinase and can cause selective cytotoxicity of melanocytes and melanoma cells. Previously, in order to improve the adsorption of magnetite nanoparticles to target cell surfaces, and generate heat in an alternating magnetic field (AMF) for cancer hyperthermia, we produced hyperthermia using magnetite cationic liposomes (MCL) that have a positive charge at the liposomal surface. In the present study, we constructed 4‐S‐CAP‐loaded MCL (4‐S‐CAP/MCL), which act as a novel modality, combining melanoma‐specific chemotherapy by 4‐S‐CAP with intracellular hyperthermia mediated by MCL. The 4‐S‐CAP/MCL exerted 4‐S‐CAP‐mediated anticancer effects on B16 melanoma cells in vitro and in vivo. Moreover, after intratumoral injection of 4‐S‐CAP/MCL in vivo, the melanoma nodules were heated to 45°C under an AMF. Significantly higher therapeutic effects were observed in mice treated with the combination therapy mediated by 4‐S‐CAP/MCL plus AMF irradiation compared with mice treated with 4‐S‐CAP/MCL alone (without AMF) or mice treated with hyperthermia alone (MCL + AMF irradiation). These results suggest that this novel therapeutic tool is applicable to the treatment of malignant melanoma. (Cancer Sci 2007; 98: 424–430)

Agouti protein, mahogunin, and attractin in pheomelanogenesis and melanoblast-like alteration of melanocytes: a cAMP-independent pathway

Melanocortin‐1 receptor (MC1R) and its ligands, α‐melanocyte stimulating hormone (αMSH) and agouti signaling protein (ASIP), regulate switching between eumelanin and pheomelanin synthesis in melanocytes. Here we investigated biological effects and signaling pathways of ASIP. Melan‐a non agouti (a/a) mouse melanocytes produce mainly eumelanin, but ASIP combined with phenylthiourea and extra cysteine could induce over 200‐fold increases in the pheomelanin to eumelanin ratio, and a tan‐yellow color in pelletted cells. Moreover, ASIP‐treated cells showed reduced proliferation and a melanoblast‐like appearance, seen also in melanocyte lines from yellow (Ay/a and Mc1re/ Mc1re) mice. However ASIP‐YY, a C‐terminal fragment of ASIP, induced neither biological nor pigmentary changes. As, like ASIP, ASIP‐YY inhibited the cAMP rise induced by αMSH analog NDP‐MSH, and reduced cAMP level without added MSH, the morphological changes and depigmentation seemed independent of cAMP signaling. Melanocytes genetically null for ASIP mediators attractin or mahogunin (Atrnmg‐3J/mg‐3J or Mgrn1md‐nc/md‐nc) also responded to both ASIP and ASIP‐YY in cAMP level, while only ASIP altered their proliferation and (in part) shape. Thus, ASIP–MC1R signaling includes a cAMP‐independent pathway through attractin and mahogunin, while the known cAMP‐dependent component requires neither attractin nor mahogunin.

DOSE-DEPENDENT INDUCTION OF IL-12 BUT NOT IL-10 FROM HUMAN KERATINOCYTES AFTER EXPOSURE TO ULTRAVIOLET LIGHT A

Ultraviolet light A (UVA) is shown to play an augmentative or synergistic role with UVB in pathophysiological conditions induced by solar radiation. Thus, UVA would contribute significantly to the development of skin malignancies. It remains unclear, however, how UVA contributes to solar radiation‐induced immune suppression. Keratinocytes (KC) produce cytokines which are a significant mediator of inflammatory and immunologic reactions in skin exposed to solar radiation and are a potent mediator in the induction of immune suppression. To examine if UVA alters the expression and production of cytokines from KC, normal human keratinocytes (HuSK) were cultured and exposed to UVA at doses ranging between 2.5 and 20 kJ/m2. Constitutive expression of the p35 subunit of interleukin (IL)‐12 was detected by reverse transcription‐polymerase chain reaction (RT‐PCR) and the p40 subunit was induced by UVA irradiation dose dependently. IL‐12 protein was also detected in the supernatants from UVA‐irradiated HuSK by enzyme‐linked imuunosorbent assay (ELISA) and confirmed by a bioassay. On the other hand, the same doses of UVA did not induce IL‐10 mRNA or IL‐10 protein which has been shown to be one of the cytokines responsible for the induction of UVB‐induced immunosuppression. Considering that IL‐12 promotes activation of Th1 cells and prevents the activation of Th2 cells and that administration of IL‐12 has been shown to block the induction of immune suppression in UV‐irradiated animals, our results suggest that UVA modulates skin immune function distinctively from UVB by affecting the balance between IL‐10 and IL‐12 produced from KC. J. Cell. Physiol. 177:493–498, 1998.

Prolonged survival of rat skin allograft by treatment with FK506 ointment

BACKGROUNDnWe studied the effect of FK506 ointment on rat skin allograft survival.nnnMETHODSnLewis rat (RT1(1)) skin allografts were histologically evaluated on day 7 after transplantation to recipient ACI (RT1a) rats. We set histological gradings for rejection as follows: grade 1, intraepidermal blister formation; grade 2, incomplete epidermal separation from the dermis; and grade 3, complete epidermal separation from the epidermis. According to these histological criteria, the immunosuppressive effect of FK506 ointment was assessed.nnnRESULTSnOur data indicated that all recipient rats without FK506 ointment showed grade 3 rejection on day 7 after transplantation. In contrast, the allografts treated with FK506 ointment showed grade 1 rejection. Furthermore the blood concentration of FK506 was below 0.5 ng/ml, minimizing the systemically adverse effects of FK506.nnnCONCLUSIONSnThus, the present study suggests that the topical administration of FK506 on the skin allografts may be useful and effective in the suppression of skin allograft rejection.

N-Propionyl-Cysteaminylphenol-Magnetite Conjugate (NPrCAP/M) Is a Nanoparticle for the Targeted Growth Suppression of Melanoma Cells

A magnetite nanoparticle, NPrCAP/M, was produced for intracellular hyperthermia treatment of melanoma by conjugating N-propionyl-cysteaminylphenol (NPrCAP) with magnetite and used for the study of selective targeting and degradation of melanoma cells. NPrCAP/M, like NPrCAP, was integrated as a substrate in the oxidative reaction by mushroom tyrosinase. Melanoma, but not non-melanoma, cells incorporated larger amounts of iron than magnetite from NPrCAP/M. When mice bearing a B16F1 melanoma and a lymphoma on opposite flanks were given NPrCAP/M, iron was observed only in B16F1 melanoma cells and iron particles (NPrCAP/M) were identified within late-stage melanosomes by electron microscopy. When cells were treated with NPrCAP/M or magnetite and heated to 43 degrees C by an external alternating magnetic field (AMF), melanoma cells were degraded 1.7- to 5.4-fold more significantly by NPrCAP/M than by magnetite. Growth of transplanted B16 melanoma was suppressed effectively by NPrCAP/M-mediated hyperthermia, suggesting a clinical application of NPrCAP/M to lesional therapy for melanoma. Finally, melanoma cells treated with NPrCAP/M plus AMF showed little sub-G1 fraction and no caspase 3 activation, suggesting that the NPrCAP/M-mediated hyperthermia induced non-apoptotic cell death. These results suggest that NPrCAP/M may be useful in targeted therapy for melanoma by inducing non-apoptotic cell death after appropriate heating by the AMF.

Malignant melanoma in a patient with oculocutaneous albinism.

Background: Sun-induced malignancies (basal cell and squamous cell carcinomas) are common in oculocutaneous albinism, however, the incidence of malignant melanoma is a topic of controversy. Objective: We have reviewed the literature and report a case of a woman with oculocutaneous albinism with an amelanotic melanoma of the anterior chest wall. Results: There are only 26 previously reported cases (both case reports and African albino population studies) in 25 patients in the literature. A 27th case with immunohistochemical and ultrastructural evaluation is presented. Conclusions: It appears that melanoma, a malignancy for which sun exposure and light colouration are felt to be major risk factors, has a low incidence among a population that is both hypopigmented and often exposed to high levels of ultraviolet light. This low incidence is poorly understood and frequently disputed.