Tatsuya Horikawa

UV-induced skin damage

Solar radiation induces acute and chronic reactions in human and animal skin. Chronic repeated exposures are the primary cause of benign and malignant skin tumors, including malignant melanoma. Among types of solar radiation, ultraviolet B (290-320 nm) radiation is highly mutagenic and carcinogenic in animal experiments compared to ultraviolet A (320-400 nm) radiation. Epidemiological studies suggest that solar UV radiation is responsible for skin tumor development via gene mutations and immunosuppression, and possibly for photoaging. In this review, recent understanding of DNA damage caused by direct UV radiation and by indirect stress via reactive oxygen species (ROS) and DNA repair mechanisms, particularly nucleotide excision repair of human cells, are discussed. In addition, mutations induced by solar UV radiation in p53, ras and patched genes of non-melanoma skin cancer cells, and the role of ROS as both a promoter in UV-carcinogenesis and an inducer of UV-apoptosis, are described based primarily on the findings reported during the last decade. Furthermore, the effect of UV on immunological reaction in the skin is discussed. Finally, possible prevention of UV-induced skin cancer by feeding or topical use of antioxidants, such as polyphenols, vitamin C, and vitamin E, is discussed.

Association of human herpesvirus 6 reactivation with the flaring and severity of drug-induced hypersensitivity syndrome

Background  Drug‐induced hypersensitivity syndrome (DIHS) is an adverse reaction with clinical signs of fever, rash and internal organ involvement. In the vast majority of patients in Japan, the causative drugs for DIHS are limited to the following eight: carbamazepine, phenytoin, phenobarbital, zonisamide, mexiletine, dapsone, salazosulfapyridine and allopurinol. The association of human herpesvirus (HHV)‐6 reactivation with DIHS has been reported by various groups.

Pirfenidone suppresses tumor necrosis factor-α, enhances interleukin-10 and protects mice from endotoxic shock

A new experimental drug, pirfenidone (5-methyl-1-phenyl-1H-pyridine-one; S-7701), has been reported to have beneficial effects for the treatment of certain fibrotic diseases. We investigated the anti-inflammatory properties in murine endotoxic shock to determine the pharmacological characteristics. The present study describes the prophylactic effect, cytokine regulatory profiles and therapeutic effect of pirfenidone in murine endotoxic shock, which was induced in mice using an intraperitoneal (i.p.) injection of lipopolysaccharide and D-galactosamine. First, we examined the prophylactic effect and cytokine regulatory profiles. A single oral administration of pirfenidone prior to lipopolysaccharide/D-galactosamine challenge inhibited the production of circulating tumor necrosis factor-alpha (TNF-alpha), interleukin-12 and interferon-gamma, markedly enhanced that of interleukin-10, and offered protection from subsequent lethal symptoms in a dose-dependent manner. Second, we examined the therapeutic effect. A single oral administration of pirfenidone 1, 2, 3, 4 and 5 h post lipopolysaccharide/D-galactosamine challenge provided protection against lethal shock in a time-dependent manner. At the histopathological level, apoptotic positive cells were found to be suppressed in the liver. The transforming growth factor (TGF)-beta1 level was markedly elevated in the liver of lipopolysaccharide/D-galactosamine-challenged mice, suppressed in pirfenidone-treated mice. These findings may offer an alternative for both protective and therapeutical treatment of several human acute or chronic inflammatory diseases by pirfenidone.

Aspirin enhances the induction of type I allergic symptoms when combined with food and exercise in patients with food-dependent exercise-induced anaphylaxis

We examined the effect of aspirin as a substitute for exercise in inducing urticaria/anaphylaxis in three patients with food‐dependent exercise‐induced anaphylaxis (FDEIA). Two of the patients had specific IgE antibodies to wheat and the other had antibodies to shrimp. Administration of aspirin before ingestion of food allergens induced urticaria in one patient and urticaria and hypotension in another, while aspirin alone or food alone elicited no response. The third patient developed urticaria only when he took all three items, i.e. aspirin, food and additional exercise, whereas provocation with any one or or two of these did not induce any symptoms. These findings suggest that aspirin upregulates type I allergic responses to food in patients with FDEIA, and further shows that aspirin synergizes with exercise to provoke symptoms of FDEIA. This is the first report of a synergistic effect of aspirin in inducing urticaria/anaphylaxis, which was confirmed using challenge tests in patients with FDEIA.

Interleukin-23 and Interleukin-27 Exert Quite Different Antitumor and Vaccine Effects on Poorly Immunogenic Melanoma

Recent studies revealed that two novel interleukin (IL)-12-related cytokines, IL-23 and IL-27, have potent antitumor activities. However, the antitumor effects were mainly evaluated in relatively highly immunogenic tumors and have not been fully evaluated against nonimmunogenic or poorly immunogenic tumors. In this study, we investigated the antitumor efficacies of IL-23 and IL-27 on poorly immunogenic B16F10 melanoma and found that the antitumor responses mediated by IL-23 and IL-27 were clearly different. In syngeneic mice, mouse single-chain (sc) IL-23-transfected B16F10 (B16/IL-23) tumors exhibited almost the same growth curve as B16F10 parental tumor about until day 20 after tumor injection and then showed growth inhibition or even regression. In contrast, scIL-27-transfected B16F10 (B16/IL-27) tumors exhibited significant retardation of tumor growth from the early stage. In vivo depletion assay revealed that the antitumor effect of B16/IL-23 was mainly mediated by CD8+ T cells and IFN-gamma whereas that of B16/IL-27 mainly involved natural killer cells and was independent of IFN-gamma. We also found that antitumor effects of B16/IL-23 and B16/IL-27 were synergistically enhanced by treatment with IL-18 and IL-12, respectively. Furthermore, B16/IL-23-vaccinated mice developed protective immunity against parental B16F10 tumors but B16/IL-27-vaccinated mice did not. When combined with prior in vivo depletion of CD25+ T cells, 80% of B16/IL-23-vaccinated mice completely rejected subsequent tumor challenge. Finally, we showed that the systemic administration of neither IL-23 nor IL-27 induced such intense toxicity as IL-12. Our data support that IL-23 and IL-27 might play a role in future cytokine-based immunotherapy against poorly immunogenic tumors.

Roles for the protein tyrosine phosphatase SHP-2 in cytoskeletal organization, cell adhesion and cell migration revealed by overexpression of a dominant negative mutant.

SHP-2, a SRC homology 2 domain-containing protein tyrosine phosphatase, mediates activation of Ras and mitogen-activated protein kinase by various mitogens and cell adhesion. Inhibition of endogenous SHP-2 by overexpression of a catalytically inactive (dominant negative) mutant in Chinese hamster ovary cells or Rat-1 fibroblasts has now been shown to induce a marked change in cell morphology (from elongated to less polarized) that is accompanied by substantial increases in the numbers of actin stress fibers and focal adhesion contacts. Overexpression of the SHP-2 mutant also increased the strength of cell-substratum adhesion and resulted in hyperphosphorylation of SHPS-1, a substrate of SHP-2 that contributes to cell adhesion-induced signaling. Inhibition of SHP-2 also markedly increased the rate of cell attachment to and cell spreading on extracellular matrix proteins such as fibronectin and vitronectin, effects that were accompanied by enhancement of adhesion-induced tyrosine phosphorylation of paxillin and p130Cas. In addition, cell migration mediated by fibronectin or vitronectin, but not that induced by insulin, was impaired by overexpression of the SHP-2 mutant. These results suggest that SHP-2 plays an important role in the control of cell shape by contributing to cytoskeletal organization, and that it is an important regulator of integrin-mediated cell adhesion, spreading, and migration as well as of tyrosine phosphorylation of focal adhesion contact-associated proteins.

In vivo elimination of CD25+ regulatory T cells leads to tumor rejection of B16F10 melanoma, when combined with interleukin‐12 gene transfer

Abstract:  CD4+CD25+ T cells are an important population that plays a crucial role in the maintenance of peripheral self‐tolerance. Recently, it was shown that the elimination of these cells by in vivo administration of anti‐CD25 monoclonal antibody (mAb) caused the regression of highly immunogenic tumors in syngeneic mice. In this study, we examined whether B16F10 melanoma cells regressed with the elimination of CD25+ regulatory T cells. We found the melanoma cells were not affected at all by in vivo anti‐CD25 mAb administration alone but tumor rejection resulted in all mice when the administration was combined with IL‐12 gene transfer to tumor cells. In vivo, depletion of natural killer (NK) cells or CD8+ T cells cancelled the tumor rejection. NK‐cell depletion allowed IL‐12‐transfected B16F10 melanoma (B16/IL‐12) to grow from an early stage and resulted in a more rapid tumor growth of B16/IL‐12 than that in mice without administration of anti‐CD25 mAb. On the other hand, CD8+ T‐cell depletion did not affect the tumor growth in the early phase but allowed B16/IL‐12 to grow in rather a late phase and resulted in almost the same degree of tumor growth as in mice without administration of anti‐CD25 mAb. In a previous study, we showed that the elimination of CD4+ T cells enhanced the antitumor effect of B16/IL‐12 and induced vitiligo‐like coat color alteration. Therefore, we also examined the frequency of the change to a vitiligo‐like coat color in mice showing tumor rejection caused by CD25+ T‐cell elimination to compare with the mechanism enhancing the antitumor effects by cell elimination. The elimination of CD25+ T cells did not induce vitiligo‐like coat color changes, though that of CD4+ T cells induced the change in 60% of mice. Furthermore, we confirmed that elimination of CD25+ T cells did not affect the T‐helper (Th) 1/Th2 cytokine profile, while that of CD4+T cells abrogated the Th2 cytokines (IL‐4 and IL‐10) and resulted in a Th1‐dominant cytokine profile in the tumor‐draining lymph nodes (TDLNs) of B16/IL‐12‐bearing mice. These results indicate that in vivo depletion of CD25+ regulatory T cells is a potent useful adjuvant in immunotherapy of B16F10 melanoma, when combined with IL‐12 gene transfer and that the enhancement of the antitumor effect by CD25+ T‐cell depletion is mediated through CD8+ T cells and may differ from the enhancing mechanism caused by CD4+ T‐cell depletion.

Soybean β‐conglycinin as the main allergen in a patient with food‐dependent exercise‐induced anaphylaxis by tofu: food processing alters pepsin resistance

Background Food‐dependent exercise‐induced anaphylaxis (FDEIA) due to soybeans is a rare disorder. The allergen responsible for FDEIA due to soybeans has not yet been determined.

Anaphylaxis to polyvinylpyrrolidone after vaginal application of povidone-iodine.

A 59‐year‐old woman who had had several episodes of contact urticaria after hair treatment, developed anaphylaxis after vaginal application of povidone‐iodine solution for disinfection. Prick tests showed wheal‐and‐flare responses to both povidone‐iodine (0·1% aqueous) and polyvinylpyrrolidone (povidone, PVP) (0·001% aq.), but not to iodine or polyoxy‐ethyrenenonylphenyl ether, both of which are also contained in povidone‐iodine solution. We confirmed that basophils from her peripheral blood released considerable amounts of histamine on stimulation by PVPs. It appeared that both the shampoo and the permanent‐wave solution contained polyvinylpyrrolidone N, N‐dimethyl aminoethyl methacrylic acid copolymer diethyl sulphate solution and polyvinylpyrrolidone styrene‐copolymer emulsion. Both these agents in the hair care products provoked an immediate skin response on prick testing. We speculate that sensitization to PVP had been established by these hair care products at a beauty parlor. She was recommended to avoid PVP‐containing products and remained free from symptoms thereafter.

Antitumor Effects on Mouse Melanoma Elicited by Local Secretion of Interleukin-12 and Their Enhancement by Treatment with Interleukin-18

Abstract To investigate the mechanism of the antitumor effect of locally secreted interleukin-12 (IL-12), we introduced the IL-12 p35 and p40 cDNAs into mouse B16 melanoma cells. IL-12 gene-transfected B16 melanoma (B16/IL12) showed marked retardation of tumor growth when implanted subcutaneously into syngeneic mice. In these mice, depletion of not only Natural Killer (NK) cells but also CD8+ T cells diminished the antitumor effect of locally secreted IL-12. Immunohistochemical analysis showed that NK cells and macrophages accumulated more densely at the center and periphery of B16/IL12 tumors than that of parental B16 tumors, whereas CD4+ T cells and CD8+ T cells accumulated sparsely only at the periphery of both transfected and untransfected tumors. Systemic treatment with interleukin-18 (IL-18) markedly inhibited the growth of B16/IL12 but did not influence the tumor growth of parental B16 cells in vivo. These results suggest that local IL-12 secretion can retard the growth of B16 melanoma mediated primarily by NK cells and indirectly by CD8+ T cells and that its antitumor effect is augmented by systemic treatment with the novel cytokine IL-18.