Epidermal Hyperproliferation With Less Prominent Dermal Inflammation Is the Unique Histopathological Feature of the Refractory Lesions in Psoriasis Treated With Ustekinumab.

ABSTRACT: Although ustekinumab (UST) shows excellent efficacy in treating psoriasis, not all patients have a complete clearance rate. The purpose of this study was to investigate the histopathological characteristics of refractory psoriasis lesions in patients with excellent response to UST. Fifty-seven patients with newly diagnosed psoriasis and 66 patients with a 75% reduction in the Psoriasis Area and Severity Index score after UST treatment were included. Computer-aided image analysis was performed to measure the epidermal thickness, horny layer thickness, number of dermal vessels, and dermal inflammatory cell infiltration rate. Parakeratosis was scored using a 4-point scale. These measurements were compared between the refractory lesions of UST-treated patients and the untreated lesions of newly diagnosed patients after the adjustment for confounding factors. The dermal inflammatory cell infiltration rate was significantly lower in the refractory lesions (P = 0.022). Meanwhile, the epidermal thickness, horny layer thickness, grade of parakeratosis, and dermal vessel count did not differ between the groups (P = 0.125, 0.719, 0.542, and 0.758, respectively). Subgroup analyses were performed within the UST-treated group after dividing them into 2 groups according to the number of treatments or treatment response rates. None of these features were significantly different between the subgroups. This study suggests that the reduction of dermal inflammation by UST was not sufficient to ameliorate the epidermal changes and implies the role of the interleukin-23-independent downstream cytokine pathway in causing the refractory lesions among patients who responded well to UST. The continuation of UST treatment might not further improve epidermal alterations.

Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) Regulates Epidermal Keratinization under Psoriatic Skin Inflammation.

Psoriasis is an autoinflammatory/autoimmune skin disease and the epitome of an exaggerated primary inflammatory response in the surface barrier tissue. Despite the efficacy of dimethyl fumarate, an electrophilic drug for psoriasis management, there is a paucity of mechanistic evidence in vivo. In response to electrophiles, the Kelch-like erythroid cell-derived protein with cap-n-collar homology-associated protein 1/nuclear factor erythroid 2-related factor 2 (NRF2) system mediates a myriad of cytoprotective mechanisms, including the regulation of excessive inflammatory response and epidermal differentiation. Because the psoriasiform tissue reaction comprises neutrophil infiltration and parakeratotic scaling, it is hypothesized that Nrf2 not only regulates inflammatory responses but also maintains epidermal differentiation, a hallmark of epidermal homeostasis. By using the imiquimod-induced cutaneous inflammation model, an exaggerated inflammatory response and impaired epidermal differentiation in Nrf2-/- mice was detected. Dimethyl fumarate treatment in Nrf2+/+ mice attenuated a psoriasiform tissue reaction and rescued epidermal differentiation, which was not observed in Nrf2-/- mice. In accordance with the fact that psoriasis plaques form well-demarcated parakeratotic lesions in association with the psoriasiform tissue reaction, the lesional skin showed reduced expression levels of NRF2 and its downstream target genes compared with nonlesional skin. In conclusion, Nrf2 attenuates the psoriasiform tissue reaction and underscores the mechanistic legitimacy of the electrophile-based approach for the management of psoriasis.

Aluminum Chloride-Induced Apoptosis Leads to Keratinization Arrest and Granular Parakeratosis.

Aluminum chloride (AlCl3) is the main active ingredient in commonly used antiperspirant. Antiperspirant use may cause a rare keratinization disease, granular parakeratosis (GP), then AlCl3 may be associated with the etiology of GP. The objective of this study is to elucidate the skin effect of topical aluminum application using a mouse model. We sprayed 20% aluminum chloride every day on the depilated mice skin and analyzed the skin clinically, histopathologically, and immunohistologically. We have succeeded in the histological replication of GP on mouse skin. The basophilic granules in the stratum corneum contained filaggrin, and processing of profilaggrin to filaggrin was disrupted in aluminum-treated mouse skin (Al-mouse). In Al-mouse, cytochrome c and cleaved-caspase 3 were upregulated mainly in the granular layer, and caspase 3 p20 subunit was upregulated. TUNEL-positive cells increased significantly in the Al-mouse from the granular to the horny layer. Caspase 3 inhibitor inhibited granular parakeratotic change of Al-mouse. Our results indicated that aluminum-induced apoptosis leads to keratinization arrest and acceleration of nuclear degradation before completion of profilaggrin processing. This could lead to retention of the basophilic granules composed of underprocessed profilaggrin in the horny layer of Al-mouse skin, the hallmark of GP.

Granular parakeratosis induced by benzalkonium chloride exposure from laundry rinse aids.

Benzalkonium chloride is a quaternary ammonium cationic detergent present in a number of household products, which can act as a major skin irritant. We present the case of six children who developed granular parakeratosis after exposure to benzalkonium chloride in laundry rinse aids, presenting as a brightly erythematous, tender but minimally pruritic, intertriginous eruption followed by superficial desquamation. The eruptions resolved over 3-4 weeks after cessation of exposure.

Response of the Endothelium to the Epicutaneous Application of Leukotriene B4.

BACKGROUND: Vascular changes, both endothelial and functional, are crucial events in inflammatory responses. OBJECTIVES: To investigate the dynamics of endothelial cell (EC) and functional changes during acute inflammation in an in vivo model of the skin using leukotriene B4. METHODS: EC proliferation, vascular network size, vessel diameter (VD), and hypoxia-inducible factor (HIF)-1α were studied by immunohistochemical CD31/Ki67 double staining and single staining of HIF-1α. Cutaneous perfusion (CP) was assessed using the Twente Optical Perfusion Camera. RESULTS: The initial phase illustrated an increase in VD, Ki67+ EC, and HIF-1α expression and late-phase vascular expansion. The HIF-1α and Ki67+ EC expression was limited. CP and VD were augmented after 24 h. CONCLUSION: The early phase of inflammation is characterized by EC proliferation and HIF-1α expression. Vascular expansion continues over time. CP and VD are seen in both phases of inflammation. Angiogenesis, vascular network formation, and perfusion are time-dependent processes which are mutually related during inflammation.

Granular parakeratosis secondary to benzalkonium chloride exposure from common household laundry rinse aids.

AIM: Granular parakeratosis (GP) is a benign dermatosis characterised by a rash at intertriginous sites. The pathogenesis is uncertain although it is proposed to be an irritant contact reaction with cases related to benzalkonium chloride (BAC) reported. Our experience is that patients often have delayed diagnosis. This study aims to review the clinical presentation and histopathological features of GP. METHODS: This study is a retrospective case series of adult and paediatric patients seen at dermatology clinics in Auckland, New Zealand. Information was collected on patient demographics, presentation, investigations and management. RESULTS: Thirteen cases (seven adults; six children) are included. The typical presentation of GP was erythematous or brown, scaly papules and plaques with desquamation in a predominantly flexural distribution. All patients reported recent exposure to BAC in laundry rinse solution. Nine biopsies were taken from four patients. Psoriasiform and eczematous findings were common on histopathology. The mainstay of treatment was cessation of BAC exposure. CONCLUSION: GP has a distinct clinical pattern although histopathological findings are varied. Clinicians should have a high index of suspicion for GP in patients presenting with erythematous flexural eruptions and seek a history of BAC exposure, especially in the context of the COVID-19 pandemic and increased antiseptic use.

Necrolytic acral erythema without hepatitis C infection.

Necrolytic acral erythema is a newly described entity characterized by sharply demarcated scaly plaques on the dorsum of the hands and feet. More than 30 patients have been reported since 1996, all of whom had anti-hepatitis C virus antibody. A 32-year-old Taiwanese woman had been diagnosed with and treated for systemic lupus erythematosus with lupus nephritis about 10 years earlier. Soon thereafter, she noted several well-demarcated keratotic plaques with erythematous borders on her feet, with sparing of the soles. Histopathology showed diffuse parakeratosis with a neutrophil infiltrate, hypogranulosis, pale upper keratinocytes, scattered and grouped dyskeratotic cells, psoriasiform hyperplasia and a mild lymphocytic infiltrate in the upper dermis. The diagnosis was made after three biopsies. The lesions regularly worsened just before and during menstruation, but patch and intradermal tests for progesterone and estrogen were negative. There was no evidence of either hepatitis B or hepatitis C infection. The lesions did not respond to treatment with zinc. The rash regressed spontaneously when corticosteroids were stopped and recurred when they were restarted, finally resolving completely after she was treated with high-dose pulse steroids for her lupus.

Granular parakeratosis in a patient treated with liposomal doxorubicin for ovarian carcinoma.

Granular parakeratosis is a rare benign dermatosis caused by an acquired disorder of keratinization that usually manifests with reddish-brown keratotic papules and plaques in intertriginous areas. It has specific histologic features but its pathogenesis remains unclear. Its frequency is probably underestimated because the condition is usually misdiagnosed as simple intertrigo. We report herein a new case of granular parakeratosis in a woman treated with liposomal doxorubicin for ovarian carcinoma that showed complete remission after discontinuation of chemotherapy. The relationship between granular parakeratosis and chemotherapy is discussed.

Podophyllin reaction mimicking Bowen's disease in a patient with delusions of verrucosis.

A 40-year-old woman presented with a delusion of warts on the forehead, for which she was applying podophyllin toxin. A skin biopsy was taken, which showed prominent mitotic figures in the basal and suprabasal layers of the epidermis and apoptotic keratinocytes. Histopathologically Bowen's disease was suspected, but was discounted after clinicopathological correlation was obtained and showed absence of epidermal atypia or disorganization. This case demonstrates the histological resemblance of podophyllin reaction to Bowen's disease. Differentiation of self-inflicted from organic skin disease may be difficult, especially where histopathological findings are confounded by cutaneous application of toxins.

Clinical and histopathologic analysis of 46 cases of cutaneous adverse reactions to imatinib.

BACKGROUND: Although many cases of cutaneous adverse reactions to imatinib have been reported, their clinical and histopathologic characteristics are not well documented. OBJECTIVES: The present study investigated clinical and histopathologic characteristics of cutaneous adverse reactions to imatinib. METHODS: This retrospective study referred to 46 patients who experienced cutaneous adverse reactions to imatinib. Clinical data including age, sex, skin lesion morphology, underlying disorders, and imatinib treatment parameters (duration of imatinib medication, initial dose, and treatment modifications at the time of the study) were collected. Histopathologic data were available for all patients. RESULTS: Cutaneous adverse reactions to imatinib developed at 1-24 weeks (median onset: 8 weeks) after imatinib administration. The severity of the reaction was categorized as grade 1 in 22%, grade 2 in 41%, and grade 3 in 37% of patients. Onset was earlier in high-severity reactions than in low-severity reactions. The severity of the reaction was dependent on imatinib dose. Grade 3 reactions were noted in nine of 16 (56%) patients administered "high-dose" (600 mg/d) imatinib. Spongiosis (78% of patients) and papillary dermal edema (83% of patients) were common histopathologic findings in the epidermis and dermis, respectively. Lymphohistiocytes were more predominant than eosinophils in dermal inflammatory infiltration. Histopathologic findings did not differ according to dose of imatinib or severity of the reaction. CONCLUSIONS: Although the clinical features of cutaneous adverse reactions to imatinib depend on imatinib dose and the severity of the reaction, histopathologic findings are not associated with these clinical variables.

Modeling acne in vitro.

To help elucidate the factors responsible for the infundibular changes seen in acne, the human sebaceous pilosebaceous infundibulum was isolated by microdissection and maintained for 7 d in keratinocyte serum-free medium supplemented with 50 micrograms/ml bovine pituitary extract, 100 units/ml penicillin and streptomycin, 2.5 micrograms/ml amphotericin B and CaCl2(10H2O) to give a final Ca2+ concentration of 2 mM. Infundibular structure was maintained over 7 d in this medium; the pattern of cell division mimicked that in vivo. The rate of cell division was significantly higher than previously described for infundibula maintained in supplemented William's E medium, and moreover did not fall over 7 d. The addition of 1 ng/ml interleukin-1 alpha (IL-1 alpha) caused hypercornification of the infundibulum similar to that seen in comedones; this could be blocked by 1000 ng/ml interleukin-1 receptor antagonist (IL-1ra). In about 20% of subjects there was spontaneous hypercornification of the infundibulum that could be blocked by 1000 ng/ml IL-1ra, suggesting that the infundibulum is capable of synthesising IL-1 alpha. The addition of 5 ng/ml epidermal growth factor or 5 ng/ml transforming growth factor-alpha to the medium caused a disorganisation of the keratinocytes of the infundibulum that resulted in rupturing similar to that seen in the more severe, purulent grades of acne. The addition of 1 microM 13-cis retinoic acid caused a significant reduction in the rate of DNA synthesis and apparent parakeratosis. We are now, therefore, able to model histologically the major infundibular changes in acne.

Epimorphin-derived peptide antagonists remedy epidermal parakeratosis triggered by unsaturated fatty acid.

BACKGROUND: Unsaturated fatty acid from accumulated sebum disrupts calcium influx in keratinocytes and triggers epidermal hyperplasia, leading to comedone formation in the skin. Oleic acid, a representative unsaturated fatty acid, has been shown to be a useful reagent to induce these cellular alternations, however, the detailed mechanism still remains to be elucidated. OBJECTIVES: This study aimed at the identification of the mediator of unsaturated fatty acid-caused epidermal hyperplasia so as to generate the effective therapeutic agents. METHODS: The downstream mediator of oleic acid-treatment was identified in the epidermal keratinocyte and the effect of its antagonistic peptides on the epidermal behaviors was investigated in culture and in vivo. RESULTS: In culture, treatment with oleic acid augmented extracellular secretion of epimorphin in HaCaT keratinocytes and prevented the epidermal terminal differentiation including programmed cell death and cornified envelope formation. The antagonistic peptide of epimorphin (EPn1: a circular compound composed of CGSIEQSC), which was newly generated in this study, restored normal keratinocyte behaviors. In hairless mice, topical application of oleic acid to the dorsal skin caused epidermal hyperplasia with decreased enucleation in the horny layer, which was dramatically hampered by the administration of EPn1. CONCLUSIONS: The effects of unsaturated fatty acid are attributed to the overstimulation of epimorphin signaling and suggest the epimorphin antagonist as a possible therapeutic agent for acne and hyperkeratotic skin disease.