Effect of prolactin-induced protein on human skin: new insight into the digestive action of this aspartic peptidase on the stratum corneum and its induction of keratinocyte proliferation.

Human prolactin-induced protein (PIP) is a major protein found in exocrine fluids such as saliva and sweat. Intriguingly, PIP possesses residues (human PIP (hPIP): PIP (29-63)) that display similarity to the aspartic peptidase candidapepsin. Here, we aimed to determine the effect of PIP as a protease on normal skin structure. Using an adhesive tape-stripping technique, we applied hPIP peptide on the corneocytes of normal-appearing facial skin from infants with eczema and healthy infants and then analyzed the morphological structure of corneocytes with Nile Red fluorescence. We also repeatedly applied the hPIP peptide onto the surface of a three-dimensional (3-D) human skin model and then analyzed any changes to the stratum corneum and epidermis using light microscopy and scanning electron microscopy. In both infant groups, a decrease in hydrophobic lipids from the cornified envelope was observed after treatment with hPIP. The peptide hPIP appeared to digest the fine structure of the stratum corneum and induce a proliferation of epidermal keratinocytes within the 3-D human skin model. Our results suggest that aspartic peptidase of PIP found in sweat or saliva deteriorates the skin barrier in a de novo manner, which potentially leads directly to the proliferation of epidermal keratinocytes without any external antigenic factors.

Aggravation of atopic dermatitis in breast-fed infants by tree nut-related foods and fermented foods in breast milk.

Ninety-two exclusively breast-fed Japanese infants with atopic dermatitis were studied to see whether tree nut-related foods (chocolate and coffee) and fermented foods (cheese, yogurt, bread, soy sauce, miso soup and fermented soy beans) eaten by their mothers affected their skin condition. Of the 92 infants, 67 (73%) showed improvement of skin lesions when their mothers avoided these foods and showed aggravation of skin lesions when these foods were reintroduced. The predominant offending foods were chocolate, yogurt, soy sauce and miso soup. A long-term maternal exclusion of the trigger foods brought about progressive improvement of skin lesions in the majority of the infants. These findings suggest that tree nut-related foods and fermented foods are important offending foods of atopic dermatitis in breast-fed infants.

Role of foods in irregular aggravation of skin lesions in children with atopic dermatitis.

Atopic dermatitis is a common inflammatory skin disease that especially affects children and adolescents. Many environmental factors have been recognized as relevant in aggravating skin lesions of the disease. However, it remains to be determined whether foods play a role in worsening of skin lesions in children with atopic dermatitis. In the present study, we investigated whether foods play a role in irregular aggravation of skin lesions in children with the disease. The study population consisted of 69 patients aged 3-15 years with atopic dermatitis. They were hospitalized and open challenge tests were performed with suspected foods. Photographs of representative skin lesion sites were taken at baseline and before and after the challenge. We determined challenge-positive foods by evaluating the comparable before/after challenge photographs. One to three (average, 1.9) challenge-positive foods were confirmed in 52 (75%) of the 69 patients examined. Predominant offending foods were chocolate, cheese and yogurt. Specific immunoglobulin E values to offending foods were mostly negative. We asked patients to exclude challenge-positive foods from their diets. They were then discharged and followed up for 3 months at our outpatient clinic. Exclusion of the offending foods for 3 months brought about a remarkable improvement in the disease. These results suggest that foods play an important role in irregular aggravation of skin lesions in children with atopic dermatitis.

Unique mutations in the filaggrin gene in Japanese patients with ichthyosis vulgaris and atopic dermatitis.

BACKGROUND: Filaggrin is a key protein involved in skin barrier function. Recently, mutations in the filaggrin gene, FLG, were identified in European families with ichthyosis vulgaris (IV) and shown to be an important predisposing factor for atopic dermatitis (AD). OBJECTIVE: To study the role of FLG mutations in IV/AD in Japan. METHODS: The known filaggrin mutations were studied by genotyping and new mutations identified by DNA sequencing. RESULTS: The European-specific mutations R501X and 2282del4 were absent from 253 Japanese individuals. We therefore sequenced the FLG gene in 4 Japanese families with IV and identified 2 novel mutations, 3321delA and S2554X. Immunohistologic and ultrastructural observations indicated that both truncation mutations lead to a striking reduction of keratohyalin granules in the epidermis. We screened 143 Japanese patients with AD for these FLG null mutations and identified them in 8 patients with AD (5.6%), including S2554X in 6 patients (4.2%) and 3321delA in 2 patients (1.4%). Both null variants were absent from 156 unrelated Japanese nonatopic and nonichthyotic controls, giving a significant statistical association between the FLG mutations and AD (chi(2)P value, .0015). This is the first report of FLG mutations in a non-European population. CONCLUSION: Our data indicate that FLG mutations in Japan are unique from those found in European-origin populations. CLINICAL IMPLICATIONS: Filaggrin null variants are also significant predisposing factors for AD in Japan and, on the basis of the recent European studies, may predict a more severe and persistent form of atopy.

Functional SNPs in the distal promoter of the ST2 gene are associated with atopic dermatitis.

Atopic dermatitis (AD) is a common inflammatory skin disease associated with the local infiltration of T helper type 2 (Th2) cells. The ST2 gene encodes both membrane-bound ST2L and soluble ST2 (sST2) proteins by alternative splicing. The orphan receptor ST2L is functionally indispensable for Th2 cells. We found a significant genetic association between AD and the -26999G/A single nucleotide polymorphism (SNP) (chi2-test, raw P-value=0.000007, odds ratio 1.86) in the distal promoter region of the ST2 gene (chromosome 2q12) in a study of 452 AD patients and 636 healthy controls. The -26999A allele common among AD patients positively regulates the transcriptional activity of the ST2 gene. In addition, having at least one -26999A allele correlated with high sST2 concentrations and high total IgE levels in the sera from AD patients. Thus, the -26999A allele is correlated with an increased risk for AD. We also found that the -26999G/A SNP predominantly affected the transcriptional activity of hematopoietic cells. Immunohistochemical staining of a skin biopsy specimen from an AD patient in the acute stage showed ST2 staining in the keratinocytes as well as in the infiltrating cells in the dermal layer. Our data show that functional SNPs in the ST2 distal promoter region regulate ST2 expression which induces preferential activation of the Th2 response. Our findings will contribute to the evaluation of one of the genetic risk factors for AD.

Combined effect of 25-hydroxycholesterol and IL-1beta on IL-8 production in human colon carcinoma cell line (Caco-2).

Interleukin-1 beta (IL-1beta) is an important mediator in intestinal inflammation. IL-1beta promotes IL-8 production, which can be modulated by a number of factors, including oxidative stress. Interestingly, oxysterols, which are thought to contribute to inflammation in atherosclerotic plaques, are also produced by intestinal epithelial cells. Thus, we investigated the effect of oxysterols, including 25-hydroxycholesterol and 7beta-hydroxycholesterol, on IL-1beta-induced IL-8 production in Caco-2 cells (a human colon carcinoma cell line). Pre-treatment of Caco-2 cells with 25-hydroxycholesterol significantly enhanced IL-1beta-induced IL-8 expression at both mRNA and protein levels. However, 7beta-hydroxycholesterol showed very little effect on IL-8 production. Furthermore, pre-treatment with 25-hydroxycholesterol, followed by IL-1beta stimulation, enhanced IL-8 promoter activity beyond that observed with IL-1beta alone. These results suggest that 25-hydroxycholesterol enhances IL-1beta-induced IL-8 production, possibly by enhancing promoter activity.

Relative importance of IL-4 and IL-13 in lesional skin of atopic dermatitis.

BACKGROUND: Although both interleukin-4 (IL-4) and IL-13 induce immunoglobulin E (IgE) production in vitro, the relative contribution of the two cytokines in various skin lesions of atopic dermatitis remains unclear. OBJECTIVE: We examined the relative importance of IL-4 and IL-13 in lesional skin of atopic dermatitis for IgE production. METHODS: The study group comprised 28 atopic dermatitis patients with serum IgE levels more than 2000 IU/ml. The expression levels of IL-4 mRNA and IL-13 mRNA versus that of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were determined using a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) method in samples of normal-appearing skin from seven patients, very mild lesions from eight patients, subacute lesions from ten patients and lichenified lesions from ten patients with atopic dermatitis, and in samples of normal skin from six healthy control subjects. RESULTS: IL-4 mRNA expression was identified in only two of the eight very mild lesions, one of the ten subacute lesions, and none of the ten lichenified lesions, whereas IL-13 mRNA expression was identified in 27 of the 28 skin lesions of atopic dermatitis. The IL-13 mRNA/GAPDH mRNA ratios (x100) in the subacute lesions (94.4+/-20.6) and lichenified lesions (71.4+/-40.4) were significantly greater than in the skin of healthy controls (13.1+/-17.7; P<0.01, P<0.05, respectively). CONCLUSIONS: Upregulation of IL-13 mRNA in subacute and chronic lesions of atopic dermatitis along with scant expression of IL-4 mRNA suggest that IL-13 is a crucial cytokine in lesional skin.

Residual washing detergent in cotton clothes: a factor of winter deterioration of dry skin in atopic dermatitis.

Although it is well known that the skin in patients with atopic dermatitis becomes drier in winter, the mechanisms of winter deterioration of dry skin are not fully understood. Our purpose was to determine whether residual washing detergent in cotton clothes plays a role in the winter deterioration of atopic dry skin. We studied 148 Japanese patients with atopic dermatitis who visited our dermatology clinic during winter months. They wore cotton underwear, which they had washed in cold tap water. We examined the distribution of dry skin on their trunks. We then asked them to stop washing their clothes with common anionic, additive-enriched detergents, and to use a nonionic, additive-reduced detergent for a period of two weeks. Photographs of 2 or 3 representative dry skin sites on the trunk were taken before and after the trial. By comparing the before-after trial photographs, the severity of dry skin at the end of the trial was assessed on a 5-point scale ranging from markedly improved to worsened. Of the 148 patients examined, 115 (78%) had widespread or localized dry skin on the trunk. The dryness of the skin was prominent around the shoulders. Of these 115 patients, 87 (76%) showed marked or moderate improvement of dry skin after the two-weeks of use of the nonionic, additive-reduced washing detergent. No patient showed worsening of the dry skin. These results suggest that residues of common washing detergents in cotton underclothes play an important role in the winter deterioration of dry skin in patients with atopic dermatitis who use cold tap water for washing their clothes.

Role of foods in irregular aggravation of atopic dermatitis.

Although it is well known that patients with atopic dermatitis often show unpredictable, irregular aggravation of skin lesions, there are no previously published studies examining trigger factors for such unpredictable aggravation. We investigated whether foods play a role in the unpredictable, irregular worsening of atopic dermatitis. The patient group included 195 Japanese adult patients with atopic dermatitis who showed unpredictable, irregular aggravation of skin lesions. They were hospitalized and openly challenged with suspected foods. Photographs of representative skin lesion sites were taken at baseline and before and after the challenge. Challenge-positive foods were determined by evaluating the comparable before-after challenge photographs. One to three (average: 1.7) challenge-positive foods were confirmed in 86 (44%) of the 195 patient examined. Predominant offending foods were chocolate, cheese, coffee, yogurt and some Japanese foods such as glutinous rice cake, soy sauce and fermented soybeans. Specific IgE values to the offending foods were mostly negative. Patients were asked to exclude challenge-positive foods from their diets. They were then discharged and followed up for 3 months at our outpatient clinic. Exclusion of the offending foods for 3 months brought about a progressive improvement of the disease. These results suggest that foods play an important role in unpredictable, irregular aggravation of skin lesions in patients with atopic dermatitis.

Premenstrual deterioration of skin symptoms in female patients with atopic dermatitis.

BACKGROUND: Although it has been recognized that women with atopic dermatitis often show menstrual-cycle-associated skin deterioration, information about this subject is meager. OBJECTIVE: To clarify the clinical features of the monthly worsening of atopic dermatitis. METHODS: A total of 286 Japanese women with atopic dermatitis were interviewed to see whether the menstrual cycle had any influence upon their skin lesions, and whether they had symptoms of premenstrual syndrome. Patients suffering from monthly skin deterioration were then observed during and after the monthly worsening. RESULTS: Of the 286 patients interviewed, 134 (47%) had monthly skin deterioration, most of which occurred in the premenstrual week. There was individual difference in severity of the monthly skin worsening. All patients with the premenstrual skin aggravation had symptoms of premenstrual syndrome. CONCLUSIONS: Premenstrual worsening of skin lesions occurs in approximately half of women with atopic dermatitis. The premenstrual skin deterioration is related to the premenstrual syndrome.

Occurrence of patchy parakeratosis in normal-appearing skin in patients with active atopic dermatitis and in patients with healed atopic dermatitis: a cause of impaired barrier function of the atopic skin.

It remains unclear whether an impaired barrier function often seen in areas of normal-appearing skin in patients with active atopic dermatitis (AD) is primary event in nature or secondary to subclinical eczematous change. We then attempted to evaluate the barrier function of normal-appearing skin in both active and healed AD patients, and as well as see whether a subclinical eczematous change exists or not in the normal-appearing skin using a non-invasive method. Transepidermal water loss (TEWL) measurement and exfoliative cytology method for corneal layer were applied in 153 AD patients who have active skin lesions and 29 individuals with completely healed AD for at least 5 years and 40 normal individuals. The TEWL of normal-appearing skin in severe, moderate and mild AD cases was 10.5+/-2.9, 8.3+/-2.4 and 7.3+/-2.1 g/m2 per h, respectively. The TEWL values in severe and moderate cases were significantly higher than the normal controls (6.2+/-1.6 g/m2 per h). However, the TEWL was not deranged in patients with completely healed AD. An exfoliative cytology examination of corneal layer disclosed that patchy parakeratosis appeared in normal-appearing skin in severe, moderate and mild AD cases at a rate of 42, 29 and 19%, respectively. However, no patchy parakeratosis was recognized in patients with completely healed AD. The occurrence of patchy parakeratosis in normal-appearing skin in patients with active AD suggests that an impaired barrier function often seen in normal-appearing skin in AD patients is secondary to subclinical eczematous change in the area.

Genetic variants of the receptors for thromboxane A2 and IL-4 in atopic dermatitis.

Thromboxane A2 (TXA2) is an arachidonate metabolite which is considered to relate to chronic inflammation in atopic diseases characterized by elevated immunoglobulin E productivity. The elevation of immunoglobulin E levels involves many molecules including interleukin-4 (IL-4) and interleukin-4 receptor alpha chain (IL-4R alpha). To assess whether genetic variants of TXA2 receptor, IL-4 and IL-4R alpha genes relate to the elevation of serum immunoglobulin E levels in patients with atopic dermatitis (AD), we conducted an association study of genetic polymorphisms of TXA2 receptor (795C/T), IL-4 (-589C/T), and IL-4R alpha (Ile50Val) in a Japanese population (n = 789). The TXA2 receptor 795TT genotype strongly related to AD with high serum immunoglobulin E concentrations. AD patients with both TXA2 receptor 795TT genotype and the IL-4R alpha Ile50/Ile50 genotype showed the greatest immunoglobulin E concentrations. These results suggest TXA2 receptor polymorphism strongly interacts with IL-4R alpha polymorphism as a major determinant of high serum immunoglobulin E levels in AD.

Sun exposure is an aggravating factor responsible for the recalcitrant facial erythema in adult patients with atopic dermatitis.

BACKGROUND: In Japan, a considerable number of adult patients with atopic dermatitis suffer from recalcitrant facial erythema that resists common treatment with topical corticosteroids and antihistamines. OBJECTIVE: Our purpose was to investigate the potential role of sun exposure in the aggravation of these facial lesions. METHODS: The history of photoaggravation was taken from 74 adult patients with atopic dermatitis who suffered from recalcitrant facial erythema. Repeated UVB and UVA phototests were performed in 36 patients. Surface markers of infiltrating cells in UVB-provoked lesions were characterized immunohistochemically. RESULTS: Forty-one of 74 patients experienced an exacerbation of the facial lesions after sun exposure. UVB testing revealed an abnormal, papular response in 14 of 36 patients. All of the 14 patients complained of clinical aggravation after sun exposure. No abnormal reactions were observed at UVA testing. In UVB-provoked lesions, CD4+ cells were predominant to CD8+ cells. CONCLUSION: Exposure to UVB radiation may be responsible for the recalcitrant facial erythema in at least some of the patients with atopic dermatitis.