IL-4 and IL-13 are not involved in IL-31-induced itch-associated scratching behaviour in mice.

Itchy skin or pruritus is a common cutaneous symptom that causes an urge to scratch, and the role of interleukins (IL) in itchy skin has been widely studied. IL-4 and IL-13 are known to induce chronic itch. Similarly, the direct role of IL-31 in inducing itch has been demonstrated in clinical situations such as atopic dermatitis and prurigo nodularis. Moreover, IL-4 receptor α antibodies (dupilumab) and IL-31 receptor A antibodies (nemolizumab) inhibit pruritus. However, the interplay between these ILs in pruritus remains unclear. Therefore, we investigated the reciprocal effects of these cytokines on pruritus in mice. The intradermal administration of IL-31 induced itch-associated scratching behaviour in a dose-dependent manner. Interestingly, the amount of IL-31 and IL-4/IL-13, co-administration or 30 min pre-administration of IL-4/IL-13 and intradermal or intravenous pre-administration of IL-4 did not affect IL-31-induced itch-associated scratching behaviour when it was observed for 30 min, 2 h, 24 h or 48 h. Pre-administration of neutralising antibodies against IL-4 and IL-13 also did not affect IL-31-induced itch-associated scratching behaviour. These results suggest that IL-31 can induce itching independently of IL-4 and IL-13 in vivo.

Oestrogen inhibits psoriasis-like dermatitis induced by imiquimod in mice in relation to increased IL-10 producing cells despite elevated expression of IL-22, IL-23, IL-17 mRNA.

Sex hormones influence the development and natural course of psoriasis. Here, we examined the effects of female sex hormones, particularly oestrogen, on psoriasis-like dermatitis induced using topical imiquimod in mice that underwent either sham operation (Sham) or ovariectomy (OVX), with (hormone replacement treatment: HRT) or without 17ß-oestradiol targeting the maximum physiological levels. The number of neutrophils in the skin was higher in the order of OVX-, Sham-, and HRT-treated mice. However, no significant difference was detected in the clinical scores among the three groups due to severe erythema and scale in a few mice out of HRT-treated mice in a set of experiments. OVX- and HRT-treated mice showed increased mRNA levels of interleukin (IL)-22 and IL-23 compared with Sham-treated mice; increased IL-10 mRNA levels were found in HRT-treated mice, possibly due to an increased proportion of forkhead box P3 (Foxp3)- and IL-10 positive large cells (possibly macrophages). In addition, HRT-treated mice had a more compact stratum corneum with higher expression of loricrin and involucrin than OVX- and Sham-treated mice. This study suggests that oestrogen has a dual potential in the pathogenesis of psoriasis: suppression of inflammation by enhancing IL-10 production and enhancement of inflammation by induction of IL-22 and IL-23 expression.

Summary of the current status of clinically diagnosed cases of Schnitzler syndrome in Japan.

BACKGROUND: Schnitzler syndrome is a rare disorder with chronic urticaria, and there is no report summarizing the current status in Japan. METHODS: A nationwide survey of major dermatology departments in Japan was conducted in 2019. We further performed a systematic search of PubMed and Ichushi-Web, using the keywords "Schnitzler syndrome" and "Japan" then contacted the corresponding authors or physicians for further information. RESULTS: Excluding duplicates, a total of 36 clinically diagnosed cases were identified from 1994 through the spring of 2022, with a male to female ratio of 1:1. The median age of onset was 56.5 years. It took 3.3 years from the first symptom, mostly urticaria, to reach the final diagnosis. The current status of 30 cases was ascertained; two patients developed B-cell lymphoma. SchS treatment was generally effective with high doses of corticosteroids, but symptoms sometimes recurred after tapering. Colchicine was administered in 17 cases and was effective in 8, but showed no effect in the others. Tocilizumab, used in six cases, improved laboratory abnormalities and symptoms, but lost its efficacy after several years. Rituximab, used in five cases, was effective in reducing serum IgM levels or lymphoma mass, but not in inflammatory symptoms. Four cases were treated with IL-1 targeting therapy, either anakinra or canakinumab, and achieved complete remission, except one case with diffuse large B-cell lymphoma. CONCLUSIONS: Since Schnitzler syndrome is a rare disease, the continuous collection and long-term follow-up of clinical information is essential for its appropriate treatment and further understanding of its pathophysiology.

Possible involvement of type 2 cytokines in alloknesis in mouse models of menopause and dry skin.

Alloknesis, an abnormal itch sensation induced by innocuous stimuli, is a key phenomenon in the vicious itch-scratch cycle in patients with atopic dermatitis. Dry skin and pruritus, including alloknesis, are major health problems in peri- and post-menopausal women. We recently reported permeability barrier dysfunction in ovariectomized (OVX) mice-a model of menopause-and found that the dysfunction was related to dry skin. However, the mechanism of the itch remains unknown. Therefore, we examined touch- and pruritogen-evoked alloknesis and epidermal innervation in OVX mice and acetone, diethyl ether and water (AEW)-treated mice, for the experimental dry skin model. Both alloknesis and epidermal innervation were comparable in OVX and AEW mice. Neutralizing antibodies against IL-4 and IL-13 inhibited alloknesis in both OVX and AEW mice as early as 30 min after intradermal administration. Comparable values close to the measurement limit of IL-4 were found in the skin of HRT and Sham mice as well as AEW and the control mice, but the levels of IL-4 were within the measurement limit in OVX mice. We could not detect mRNAs of IL-4 or IL-13 in any groups of mice. On the other hand, the number of eosinophils and basophils was increased in OVX and AEW mice. These results suggest that impaired barrier function in cooperation with type 2 cytokines derived from eosinophils and basophils in the skin or with endogenous type 2 cytokine may trigger the development of alloknesis, and thus, these cytokines could be a therapeutic target for sensitive skin.

Physiological and functional changes in the stratum corneum restored by oestrogen in an ovariectomized mice model of climacterium.

Significant decreases in hormonal levels at menopause induce physiological and functional discomfort in the skin. Representative changes at menopause are based on so-called dry skin. However, there is no evidence to explain the mechanism, even though hydration of the stratum corneum (SC) in women at menopause is comparable with that at premenopause but is enhanced by hormone replacement therapy. This study objective was to evaluate structural and functional changes in the SC in ovariectomized mice model of menopause. Hydration of the SC, recovery of the permeability barrier function, integrity and cohesion of the SC, and irritant dermatitis were analysed in mice that underwent ovariectomy with or without replacement of 17ß-estradiol. In ovariectomized mice, hydration of the SC was reduced, recovery of permeability barrier function after acute disruption was impaired, and integrity of the SC was weakened and was associated with increased cohesion and increased levels of irritant dermatitis. Oestrogen replacement treatment restored all changes. Immunohistochemistry revealed reduced levels of expression of desmoglein-1 and differentiation markers of epidermis in ovariectomized mice compared with control mice and mice with oestrogen replacement treatment. These changes might be directly associated with weakened integrity and impaired permeability barrier function of the SC in ovariectomized mice. This study results reveal that so-called dry skin at menopause is caused by not only lower hydration of the SC but also complicated structural and functional changes in the SC and skin.

Rectal carcinoma and multiple gastrointestinal stromal tumors (GIST) of the small intestine in a patient with neurofibromatosis type 1: a case report.

BACKGROUND: Neurofibromatosis type 1 (NF1) is an autosomally dominant inherited disorder characterized by multiple pigmented skin spots (café-au-lait spots) and neurofibroma. NF1 is associated with a wide variety of benign or malignant tumors. We report a NF1 patient who received surgical treatment for rectal carcinoma and multifocal small intestinal gastrointestinal stromal tumors (GISTs). CASE PRESENTATION: A 70-year-old female patient with NF1 was referred to our hospital after a positive fecal occult blood test. Locally advanced rectal carcinoma was detected in the upper rectum using colonoscopy. A submucosal tumor 20 mm in diameter was detected in the duodenal bulb during the upper gastrointestinal endoscopy. The biopsy specimen from the duodenum was GIST with positive immunostaining of KIT and CD34 microscopically. Laparoscopic low anterior resection for rectal carcinoma and local excision of the duodenal GIST were performed successfully. During the operation, five white small nodules were found on the serosa of the jejunum. One nodule was excised for histological examination. The resected rectal tumor was a well-differentiated adenocarcinoma with multiple lymph nodes metastases according to the histology. The duodenal tumor was found to be low-risk GIST. Moreover, the nodule from the jejunum was very low risk GIST. An excised skin wart was neurofibroma according to the histology. CONCLUSIONS: GIST or carcinomas have been reported to occasionally occur in the digestive tract of the patients with NF1. We present a rare case of a NF1 patient with GISTs and colorectal carcinoma.

Neutrophilic epitheliotropism, proposed as an auto-inflammatory condition of neutrophilic urticarial dermatosis including Schnitzler syndrome, is also observed in Japanese cases.

Schnitzler syndrome (SchS) is a rare autoinflammatory disease characterized by bone pain, recurrent fever, leukocytosis, and elevated C-reactive protein, along with an urticaria-like rash and monoclonal immunoglobulin (Ig)M or IgG gammopathy. Notably, the condition is distinguished by a relatively persistent recurrent urticarial-like rash. Histopathological features observed in the skin comprise diffuse neutrophil infiltration into the dermis, absence of dermal edema, and vascular wall degeneration, all of which classify SchS as a neutrophilic urticarial dermatosis (NUD). Accumulated histological data from skin biopsies of patients with NUD have revealed a sensitive histopathological marker for NUD, acknowledged as neutrophilic epitheliotropism, which has been proposed as reflecting an autoinflammatory condition. In this report, we present three SchS patients: two men (ages 55 and 68) and a woman (age 75), all displaying neutrophilic epitheliotropism in their skin biopsy specimens. Additionally, a review of eight previously reported SchS cases in Japan identified neutrophilic epithliotropism in five cases. These findings suggest that the inclination of neutrophils toward the epithelial tissue could aid in confirming diagnoses of NUD in most cases that need to be differentiated from conventional urticaria. Consequently, we emphasize that acknowledging neutrophilic epithelial predilection as a hallmark of NUD is critical for expediting early diagnosis and appropriate treatment for SchS.

The Th2 cytokine, interleukin-4, abrogates the cohesion of normal stratum corneum in mice: implications for pathogenesis of atopic dermatitis.

There is mounting evidence that Th2 cytokines adversely affect skin barrier functions and contribute to the pathogenesis of atopic dermatitis (AD). AD is also characterized by abnormal cohesion in the stratum corneum (SC). However, the contribution of Th2 cytokines to this abnormality remains unknown. This study examined the effects of IL-4, a prototypic Th2 cytokine, on the cohesion of the SC. Structural and physiological assessments revealed that repeated intradermal injections of IL-4 compromised the cohesion of the SC of normal hairless mice. Two potential mechanisms were explored to account for the altered cohesion. First, IL-4 decreased the amount of corneodesmosomes and down-regulated the expression of desmoglein 1, but not of corneodesmosin (CDSN) or loricrin expression, in murine skin and in cultured human keratinocytes (KC). IL-4 did not affect the skin surface pH, and in situ zymography revealed no net change in total serine protease activity in the IL-4-treated SC. Yet, IL-4 enhanced expression of kallikrein (KLK)7, while simultaneously down-regulating KLK5 and KLK14. Finally, IL-4 did not alter the expression of the lympho-epithelial Kazal-type inhibitor (LEKTI) in KC. This study suggests that IL-4 abrogates the cohesion of SC primarily by reducing epidermal differentiation.

Prolonged ischemia increases severity of rejection in skin flap allotransplantation in rats.

To investigate the relationship between ischemic time and rejection against allotransplants, vascularized cutaneous flaps from the groin of Brown Norway rats were transplanted to Lewis rats. The ischemic time was set at 1 hour and 6 hours for comparison. Cycrosporine A was used as the immunosuppressant. The results showed more severe rejection in the 6 hours ischemic time group in vivo, and in vitro examination using mixed lymphocyte reaction assay also demonstrated a greater antidonor response in 6 hours-ischemic group than that in 1 hour-group. Immunohistochemical study demonstrated more MHC class II antigen expression in 6 hours-ischemic group than in 1 hour-group. These results suggest that longer ischemic time induces more severe rejection against allo-transplanted tissue compared with the shorter one through an upregulation of MHC class II antigen. It is expected that these findings contribute to the studies for investigating the mechanism of rejection against the allo-transplants.

Impaired contact hypersensitivity in diet-induced obese mice.

BACKGROUND: Epidemiological studies suggest that obesity is associated with the impairment of immunity. However, there is no experimental evidence that obesity prejudices immune responses. OBJECTIVE: This study was designed to determine the effects of obesity on contact hypersensitivity (CHS) response using a diet-induced obese (DIO) mouse model. METHODS: The effect of high fat diet (HFD) on CHS response to trinitrochlorobenzene (TNCB) was assessed by ear swelling, cytokine production, functional analysis of epidermal Langerhans cells, and adoptive transfer of immune cells. Immune response to ovalbumin was also analyzed in DIO mice. RESULTS: C57BL/6 mice but not BALB/c mice that fed with HFD for 4 weeks or more became obese and showed impaired CHS response, although both strain of mice showed enhanced irritant response to TNCB. CHS response was slightly impaired when C57BL/6 mice fed with HFD for 1 or 2 weeks. This suggests that diet-induced obesity or the HFD itself impairs the CHS response in the susceptible mice. The adoptive transfer of immune cells from DIO mice sensitized with TNCB to naïve mice failed to show vigorous CHS, which suggests dysfunction of an afferent phase of CHS in DIO mice. However, the number and allo-stimulating ability of epidermal Langerhans cells were comparable between DIO mice and lean mice. In addition, the immune response to ovalbumin (delayed type hypersensitivity, and antigen-dependent production of antibodies and cytokine) was preserved in DIO mice. CONCLUSION: These results suggest that the diet-induced obesity or the HFD only partially impairs immunity in the susceptible mice.

In vivo levels of IL-4, IL-10, TGF-beta1 and IFN-gamma mRNA of the peripheral blood mononuclear cells in patients with alopecia areata in comparison to those in patients with atopic dermatitis.

Alopecia areata (AA) has been considered to be supported by an aberrant expression of IFN-gamma as a result of antigen dependent immune response. On the other hand, AA sometimes concurs with atopic diseases, although the mechanism of the concurrence is not clear. This study was designed to elucidate the immune status of AA and the similarity between AA and atopic dermatitis (AD) by analysis of in vivo levels of mRNA of Th1, Th2, and suppressive cytokines of peripheral blood mononuclear cells (PBMC). Using semiquantitative RT-PCR, the levels of cytokine mRNA were measured in freshly isolated PBMC of 47 patients with AA, 15 patients with AD, and 12 healthy controls (HC). The levels of IL-4, IFN-gamma, and TGF-beta1 mRNA were lower in patients with AA than those in HC. The levels of IL-10 mRNA in AA were comparable with those in HC. Decreased levels of IFN-gamma and TGF-beta1 were also shown in patients with AD. These results indicated a similarity (decreased levels of IFN-gamma and TGF-beta1) between AD and AA based on the cytokine profile. In addition, decreased levels of IL-4 mRNA in AA might also explain the experience that the severity of atopic disease coincident with AA is mild in the most of cases. Next, we compared the levels of these cytokine mRNA among the three subgroups of AA that were categorized based on the severity of the symptoms: mild, severe and totalis. Although there was no significant difference between any combinations of the subgroups, there was a tendency to increase the levels of IFN-gamma mRNA and to decrease the levels of IL-4 mRNA according to the severity of alopecia. However, the levels of IFN-gamma mRNA in any subgroups were less than those of HC. These results suggest that IFN-gamma is therefore involved in the pathogenesis of AA, although the information from PBMC is limited. In conclusion, AA might be induced by an aberrant expression of IFN-gamma in individuals whose PBMC produce low amounts of IFN-gamma and TGF-beta1. Further analysis is therefore required to investigate the phenotypes of the population in PBMC with or without reference to regulatory T cells.

Effects of ultraviolet B irradiation on the production of regulated upon activation normal T-cell expressed and secreted protein in cultured human epidermal keratinocytes.

The modulatory effects of ultraviolet B (UVB) irradiation on cutaneous inflammatory responses are well known but their mechanism remains obscure. It has been proposed that regulated upon activation normal T-cell expressed and secreted protein (RANTES), which is one of the chemokines produced by epidermal keratinocytes, might play an important role in the pathogenesis of cutaneous inflammatory disorders, such as atopic dermatitis and psoriasis vulgaris. This study was designed to determine whether UVB irradiation could affect the production of RANTES that is induced in cultured normal human epidermal keratinocytes upon stimulation by inflammatory cytokines. We measured levels of the transcript of the gene for RANTES in cultured keratinocytes and of RANTES itself in culture supernatants by semiquantitative reverse transcription and the polymerase chain reaction and by an enzyme-linked immunosorbant assay (ELISA), respectively. Neither the transcript nor RANTES itself was detected without prior stimulation of cells by tumor necrosis factor alpha (TNF-alpha) and/or interferon gamma (IFN-gamma) and production of RANTES was not induced by UVB (100 J/m2) irradiation alone. Cells were irradiated with UVB just before addition of TNF-alpha and IFN-gamma to the medium and then cells and culture supernatants were harvested 12, 24, and 36 h later. In both irradiated and non-irradiated cells, RANTES mRNA was first detected at 12 h and the level increased subsequently. RANTES itself was detected at 24 h, with a higher level at 36 h. At all time points examined, UVB irradiation inhibited the production of RANTES mRNA and of the protein itself. These results suggest that suppression of the production of RANTES by epidermal keratinocytes might be involved in the modulatory effects of UVB irradiation on cutaneous inflammation.

Fexofenadine, an H1-receptor antagonist, partially but rapidly inhibits the itch of contact dermatitis induced by diphenylcyclopropenone in patients with alopecia areata.

Antihistamines have been used for the treatment of not only allergic diseases such as allergic urticaria and rhinitis, but also of eczematous skin diseases because of their anti-pruritic effects. Moreover, the pruritus associated with eczematous diseases is considered to be induced, in part, by histamine. However, it is unclear whether antihistamines inhibit the itch of eczematous diseases in the absence of topical corticosteroids. In this study, we investigated the anti-pruritic effect of the antihistamine, fexofenadine, on the itch of contact dermatitis that was induced by topical application of diphenylcyclopropenone for the treatment for alopecia areata. Thirteen patients with alopecia areata, who had been treated weekly with topical immunotherapy with diphenylcyclopropenone for 3 months to 2 years, recorded the severity of their itching on a visual analog scale before and 3, 6, 12, 24, 48 and 72 h after application of diphenylcyclopropenone for 4 consecutive weeks. Seven patients took fexofenadine during the first and third weeks, and six patients took fexofenadine during the second and fourth weeks. The severity of itching reached a maximum 6-12 h after the induction of the contact dermatitis in most of the patients. However, fexofenadine partially but rapidly reduced the severity of itching for 72 h during the entire period of treatment in the absence of topical corticosteroids. Our results suggest that fexofenadine can be beneficial in the daily management of patients with itching due to eczematous disease.