Taro Masaki

Agents that reverse UV-induced immune suppression and photocarcinogenesis affect DNA repair

UV exposure induces skin cancer, in part, by inducing immune suppression. Repairing DNA damage, neutralizing the activity of cis-urocanic acid, and reversing oxidative stress abrogate UV-induced immune suppression and skin cancer induction, suggesting that DNA, UCA, and lipid photo-oxidation serve as UV photoreceptors. What is not clear is whether signaling through each of these different photoreceptors activates independent pathways to induce biological effects or whether there is a common checkpoint where these pathways converge. Here, we show that agents known to reverse photocarcinogenesis and photoimmune suppression, such as platelet-activating factor (PAF) and serotonin (5-HT) receptor antagonists, regulate DNA repair. Pyrimidine dimer repair was accelerated in UV-irradiated mice injected with PAF and 5-HT receptor antagonists. Nucleotide excision repair (NER), as measured by unscheduled DNA synthesis, was accelerated by PAF and 5-HT receptor antagonists. Injecting PAF and 5-HT receptor antagonists into UV-irradiated Xeroderma pigmentosum complementation group A-deficient mice, which lack the enzymes responsible for NER, did not accelerate photoproduct repair. Similarly, UV-induced formation of 8-oxo-deoxyguanosine was reduced by PAF and 5-HT receptor antagonists. We conclude that PAF and 5-HT receptor antagonists accelerate DNA repair caused by UV radiation, which prevents immune suppression and interferes with photocarcinogenesis.

Human Herpes Virus 6 Encephalitis in Allopurinol-induced Hypersensitivity Syndrome

Hypersensitivity syndrome is one of the most severe forms of drug eruption, and is characterized by a severe, potentially lethal, multiorgan involvement. Recently, reactivation of human herpesvirus 6 (HHV-6) has been suggested to be involved in this syndrome, although the exact role of HHV-6 remains elusive. In addition to exanthem subitum, neurological illnesses, such as infantile febrile illness without rash and encephalitis in immunocompromised patients have been attributed to HHV-6. A 51-year-old man developed a generalized erythematous eruption during treatment with allopurinol. Prednisolone improved his condition, but after the dose of prednisolone was reduced neurological abnormalities such as mental deterioration and positive meningeal signs developed. HHV-6 DNA in his blood by PCR analysis was positive. Furthermore, we detected HHV-6 DNA in the cerebrospinal fluid. The titers of anti-HHV-6-IgG increased during the course. His neurological symptoms gradually improved and no neurological sequelae were noted. Neurological abnormalities associated with hypersensitivity syndrome are very rare. However, the detection of HHV-6 DNA in the cerebrospinal fluid strongly indicates an involvement of reactivated HHV-6 in encephalitis.

Ultraviolet light induces Stat3 activation in human keratinocytes and fibroblasts through reactive oxygen species and DNA damage.

Please cite this paper as: Ultraviolet light induces Stat3 activation in human keratinocytes and fibroblasts through reactive oxygen species and DNA damage. Experimental Dermatology 2010; 19: 654–660.

Suppressive effect of recombinant human thioredoxin on ultraviolet light-induced inflammation and apoptosis in murine skin.

Thioredoxin (TRX) is a small ubiquitous protein, which regulates cellular redox status and scavenges reactive oxygen species. The present study was conducted to investigate the effect of TRX on ultraviolet (UV)‐B‐mediated inflammatory and apoptotic responses. Ear swelling after UV‐B irradiation was significantly reduced in TRX‐transgenic mice compared to wild‐type mice. Administration i.p. of recombinant human TRX also reduced acute skin inflammatory reaction, such as skin erythema and swelling. Histologically, numbers of inflammatory cells including neutrophils and lymphocytes were significantly reduced and the average size of the caliber of blood vessels were also reduced in recombinant human TRX‐injected mice. The number of apoptotic keratinocytes, in terms of sunburn cells, activated‐caspase‐3‐positive cells and terminal deoxynucleotidyl transferase dUTP nick end labeling‐positive cells were all significantly reduced in recombinant human TRX‐injected mice. Immunohistochemical intensity of 8‐hydroxy‐2′‐deoxyguanosine was strikingly reduced in recombinant human TRX‐injected mouse. Western blotting showed that administration of recombinant human TRX attenuated duration of phosphorylation of p38 mitogen‐activated protein kinases and intensity of phosphorylation of c‐Jun N‐terminal kinase in the early phase, which play important roles in inflammatory and apoptotic signaling. Collectively, these findings indicated that recombinant human TRX attenuated inflammatory and apoptotic responses caused by UV‐B. Possible mechanisms for this might be via redox regulation of stress signaling and reduction of reactive oxygen species.

High frequency of PTEN mutations in nevi and melanomas from xeroderma pigmentosum patients.

We examined nevi and melanomas in 10 xeroderma pigmentosum (XP) patients with defective DNA repair. The lesions had a lentiginous appearance with markedly increased numbers of melanocytes. Using laser capture microdissection, we performed DNA sequencing of 18 benign and atypical nevi and 75 melanomas (melanoma in situ and invasive melanomas). The nevi had a similar high frequency of PTEN mutations as melanomas [61% (11/18) versus 53% (39/73)]. Both had a very high proportion of UV‐type mutations (occurring at adjacent pyrimidines) [91% (10/11) versus 92% (36/39)]. In contrast to melanomas in the general population, the frequency of BRAF mutations (11%, 7/61), NRAS mutations (21%, 13/62), and KIT mutations (21%, 6/28) in XP melanomas was lower than for PTEN. Phospho‐S6 immunostaining indicated activation of the mTOR pathway in the atypical nevi and melanomas. Thus, the clinical and histological appearances and the molecular pathology of these UV‐related XP nevi and melanomas were different from nevi and melanomas in the general population.

Hydrochlorothiazide Enhances UVA-Induced DNA Damage

The UVA is currently thought to be carcinogenic because, similar to UVB, it induces the formation of cyclobutane pyrimidine dimers (CPDs). Various drugs have been reported to cause photosensitive drug eruptions as an adverse effect. Although the precise mechanism of photosensitive drug eruption remains to be elucidated, it is generally accepted that free radicals and other reactive molecules generated via UV‐irradiated drugs play important roles in the pathogenesis of photosensitive drug eruptions. The waveband of concern for photo‐reactive drugs is UVA‐visible light, but some extend into the UVB region. We tested whether photosensitive drugs could enhance CPD formation after UVA exposure by using isolated DNA in the presence of several reported photosensitive drugs using high‐performance liquid chromatography. We found that the diuretic agent hydrochlorothiazide (HCT) significantly enhanced the production of TT dimers over a wide range of UVA. Furthermore, we investigated whether UVA plus HCT could enhance CPD production in xeroderma pigmentosum model mice defective in nucleotide excision repair. Immunofluorescence studies showed that CPD formation in the skin significantly increased after 365 nm narrow‐band UVA irradiation in the presence of HCT, compared with that in wild‐type mice. HCT could be used with caution because of its enhancement of UVA‐induced DNA damage.

Involvement of interleukin-10 promoter polymorphisms in nonmelanoma skin cancers-a case study in non-Caucasian skin cancer patients.

Interleukin 10 (IL‐10) is a potent immunosuppressive cytokine, therefore elevated IL‐10 expression has been implicated in inhibition of antitumor immune response. IL‐10 gene promoter polymorphism has been shown to be involved in susceptibility to skin cancers, but there has been no report focusing on susceptibility to skin cancers among non‐Caucasian populations. We enrolled 129 patients with skin cancers and 50 age‐ and sex‐matched healthy controls between April 2004 and March 2007. Genomic DNA was extracted from patients’ blood samples and IL‐10 promoter polymorphisms were identified using polymerase chain reaction‐restriction fragment length polymorphism or direct sequencing. The distribution of the frequency of allele or haplotype of IL‐10 gene promoter in Japanese was quite different from that of Europeans. No significant differences could be demonstrated in the frequency of allele or haplotype of IL‐10 gene promoter between the patient group and the control group. However, the frequency of the low‐IL‐10 expression haplotype was significantly high in Bowen’s disease subgroup. The frequency of low expression IL‐10 promoter genotype was significantly less (P = 0.009, χ2 = 6.74) in the group of nonmelanoma skin cancer generated on sun‐exposed areas in comparison with that on covered areas. Our results indicated that low expression haplotype of IL‐10 in Bowen’s disease may inhibit the escape of tumor cells from immune surveillance, resulting in suppression of tumor growth and tumor invasion to the dermis. Moreover, high IL‐10‐expressing haplotype of IL‐10 promoter may be a risk factor for photocarcinogenesis.

Differences in Clinical Phenotype among Patients with XP Complementation Group D: 3D Structure and ATP-Docking of XPD In Silico

TO THE EDITOR Xeroderma pigmentosum (XP) is an autosomal recessive hereditary disease that is classified into seven genetic complementation groups, A through G, of nucleotide excision repair (NER)deficient types and one NER-proficient variant type (DiGiovanna and Kraemer, 2012). Patients with XP complementation group D (XPD) display photosensitivity, proneness to skin cancer and neurological symptoms, but the severity varies. In XPD from Western countries, the single amino-acid change R683W is found in 73% of the patients and most of them suffer from neurological symptoms (Takayama et al., 1995; Kobayashi et al., 1997; Taylor et al., 1997; Viprakasit et al., 2001; Kobayashi et al., 2002; Boyle et al., 2008; Emmert et al., 2009; Ueda et al., 2009). In contrast, Japanese patients display only skin manifestations without neurological symptoms (Kobayashi et al., 1997; Taylor et al., 1997; Kobayashi et al., 2002). XPD protein is an ATP-dependent 50-30 DNA helicase, which exerts unwinding of a damaged DNA strand to facilitate repair of the DNA. Although the human XPD protein remains refractory to crystallization, the crystal structure of XPD proteins from the archea has been solved (Fan et al., 2008; Liu et al., 2008). These structures revealed that XPD functions as a helicase with two helicase motifs separated by an ATP-binding cleft and two additional domains, a Fe–S cluster and an Arch domain. In this study, we present six cases of Japanese XPD without neurological abnormalities in four families. All patients showed severe photosensitivity since birth, and their skin in the sunexposed areas was hyperpigmented and covered with numerous pigmented maculae with color variations from light brown to dark brown. Four patients developed skin cancer, but none of them show neurological signs. XPD1KO and XPD4KO were assessed by a neurologist and an otorhinologist. Their clinical characteristics have been summarized in Table 1. To determine the ability to repair UV-induced DNA damage, a colonyformation assay after UV irradiation and UV-induced unscheduled DNA synthesis (UDS) was assessed (Materials and Methods are described in Supplementary data). The dose range giving 37% cell survival and UV-induced UDS in patients’ cells was much lower compared with that in the healthy subjects but was higher than that in XP-A cells (Table 1). Genetic complementation tests were carried out by means of a host-cell reactivation assay. Luciferase activity was increased specifically when XPD cDNA was cotransfected into each patient’s cells. Therefore, we concluded that all cases belonged to XPD. Direct sequence analysis was performed on each exon of the genomic DNA of Accepted article preview online 13 January 2014; published online 13 February 2014 Abbreviations: NER, nucleotide excision repair; UDS, unscheduled DNA synthesis; XP, xeroderma pigmentosum; XPD, xeroderma pigmentosum complementation group D E Nakano et al. Genotype–Phenotype and Protein Structure of XPD

Three school‐age cases of xeroderma pigmentosum variant type

Xeroderma pigmentosum (XP) is a photosensitive genodermatosis with increased susceptibility to skin cancers. Patients are typically diagnosed with XP when they consult a dermatologist for skin cancers.

A case of eperisone hydrochloride-induced anaphylaxis: A true type I reaction?

Centrally acting muscle relaxants (CMRs) are often used to alleviate musculoskeletal pain. Among them, eperisone hydrochloride is the most popular in Japan.1 Although it is a welltolerated drug,2 allergic reactions to eperisone have been reported, most of which are anaphylactic or urticarial reactions.1 Acute generalized exanthematous pustulosis3 and fixed drug eruption4 are reported rare manifestations of eperisone-induced drug eruption. Tolperisone hydrochloride, an analog of eperisone hydrochloride, is another CMR often used in European countries. Ribi et al. reviewed the adverse effects of tolperisone hydrochloride; almost half of the adverse effects were immediate-type hypersensitivity reactions.5 To date, reported CMR-related drug eruptions have mainly been immediate-type hypersensitivity reactions. However, it is not clear whether this hypersensitivity is IgE mediated, a so-called “true” type I allergic reaction. Here, we report a case of eperisone-induced anaphylaxis in which skin prick test (SPT) and basophil activation test (BAT) showed negative results. An oral challenge test was the most reliable procedure for diagnosing eperisone-induced immediate-type hypersensitivity. A 64-year-old woman was referred to our dermatology department to determine potential allergens causing anaphylaxis. She had taken eperisone hydrochloride and loxoprofen sodium, which resulted in urticaria, throat swelling, and loss of consciousness. She was taken to the emergency room, where she responded well to administration of corticosteroids. The patient had a history of low-back pain for which she was prescribed eperisone hydrochloride and loxoprofen sodium. She also had a history of bronchial asthma but not food allergy. SPT was negative for all tested drugs, including eperisone hydrochloride and loxoprofen sodium. Oral challenge test was negative for non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin (up to 500 mg), loxoprofen sodium (up to 60 mg), and paracetamol (up to 400 mg), indicating that the patient did not have aspirin-sensitive urticaria. Oral administration of 0.5e5 mg of eperisone induced slight itchiness on the palms. About 90 min after oral administration of 16 mg of eperisone, the patient developed general pruritus and swelling of the face, tongue, and palms (Fig. 1). Thus, she was diagnosed with eperisone hydrochloride-induced anaphylaxis. To investigate whether eperisone hydrochloride itself directly induced basophil activation, we performed a BAT.6 Contrary to