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Eric H Kowalski,1 Diana Kneiber,1 Manuel Valdebran,2 Umangi Patel,1 Kyle T Amber1 1Department of Dermatology, University of Illinois at Chicago, Chicago, IL, USA; 2Department of Dermatology, University of California, Irvine, Irvine, CA, USA Abstract: Prurigo nodualris (PN) is a chronic condition with highly pruritic, hyperkeratotic papules or nodules arising in the setting of chronic pruritus. While PN may serve as a phenotypic presentation of several underlying conditions such as atopic dermatitis, chronic kidney disease-related pruritus, and neurological diseases, it represents a distinct clinical entity that may persist despite the removal of the underlying cause, if one is identified. Neuronal proliferation, eosinophils, mast cells, and small-fiber neuropathy play a role in the production of pruritus in PN, although the exact mechanism has not yet been established. Identifying an underlying cause, if present, is essential to prevent recurrence of PN. Due to often present comorbidities, treatment is typically multimodal with utilization of topical and systemic therapies. We performed a PubMed/MEDLINE search for PN and present a review of recent developments in the treatment of PN. Treatment typically relies on the use of topical or intralesional steroids, though more severe or recalcitrant cases often necessitate the use of phototherapy or systemic immunosuppressives. Thalidomide and lenalidomide can both be used in severe cases; however, their toxicity profile makes them less favorable. Opioid receptor antagonists and neurokinin-1 receptor antagonists represent two novel families of therapeutic agents which may effectively treat PN with a lower toxicity profile than thalidomide or lenalidomide. Keywords: pruritus, chronic prurigo, neurokinin 1, thalidomide, atopic dermatitis

Eric H Kowalski,1 Diana Kneiber,1 Manuel Valdebran,2 Umangi Patel,1 Kyle T Amber11Department of Dermatology, University of Illinois at Chicago, Chicago, IL, USA; 2Department of Dermatology, University of California-Irvine, Irvine, CA, USAKolli et al shed light on a pertinent issue of poor adherence to therapy in the treatment of prurigo nodularis (PN).1 While our intention was to cover recalcitrance in the sense of medical failure, Kolli et al bring up an extremely valuable point: adherence to therapy is dismal.2 Escalation of therapy as a result of poor compliance may result in unintended adverse effects from the more potent systemic therapies delineated in the treatment of PN. Thus, ensuring compliance with the treatment protocol should be a priority.In our view, PN is most often a phenotypic manifestation of chronic pruritus secondary to a host of diseases. Presumably, the relative adherence to treatment for the underlying cause of the PN, in cases where there is one, has a large role to play in the recalcitrance of the PN. This is perhaps most glaring in the case of atopic dermatitis (AD). AD has been identified to contribute to PN development in nearly 50% of PN patients.3 Assessment of nonadherence, as well as steroid phobia has been well documented in the AD population and almost certainly contributes to the development of clinically deemed recalcitrant PN in this population.4,5 Because of the well-established efficacy of topical corticosteroids in the treatment of atopic dermatitis, it is likely that atopic PN would prove more responsive. Thus, “treatment resistant” atopic PN, requires serious con- sideration of nonadherence. Clinical data on nonadherence in nonatopic PN patients, however, remains undetermined.Regardless of the primary underlying cause, patients receiving supervised phototherapy in the outpatient setting offer insight into truly recalcitrant PN due to complete adherence. A recent review on phototherapy in treatment of PN showed that in 5 out of 11 studies, patients experienced recalcitrant disease.6 Thus, even in a supervised setting where adherence could be monitored, numerous cases were recalcitrant.Innovation in adherence strategies across a wide spectrum of therapies ideally will result in fewer “treatment-resistant” cases.7–9 We agree with Kolli et al, that it remains vital to distinguish between poor adherence and medical failure.This is in response to the Letter to the Editor

Dermatological conditions constituting the group of autoimmune blistering diseases (AIBD) are characterized by loss of immunotolerance and humoral, as well as cellular, autoimmune responses that result in the development of bullae and erosions on the skin and mucous membranes. AIBDs are broadly categorized into pemphigus and pemphigoid classes with several distinct subtypes amongst them. Advances in genetics have allowed for the study and identification of alleles, and even single nucleotide polymorphisms, that harbor increased susceptibility or confer protection for the development of these conditions. The focus of this chapter pertains to a comprehensive review of the known genetic associations with AIBDs, including HLA class I-III, as well as non-HLA genes and non-coding sequences that influence cellular processes and signaling pathways., (© 2022. Springer Nature Switzerland AG.)

Current methods of assessing immunohistochemistry center on semiquantitative visual grading scales. More objective methods utilizing digital quantification offer superior precision and, presumably, higher confidence with image comparison. However, their cost often remains prohibitive, and there is little customizability to separate subsections of interest in the tissue. Here we describe a method using two open-source software programs to analyze the intensity and density of signals in immunohistochemistry-stained tissue sections that account for tissue heterogeneity and allow for direct comparison between two samples. This method allows for quantitative assessment of epidermal protein expression. We herein demonstrate this workflow using an epidermal stain tothymic stromal lymphopoietin.

Autoimmune blistering diseases comprise a group of heterogenous conditions characterized by the loss of tolerance and subsequent development of autoantibodies targeting epidermal and subepidermal adhesion proteins. Blisters and erosions form on the skin and mucous membranes leading to significant morbidity and mortality. Traditional therapies rely on systemic immunosuppression. Advancements in our understanding of the pathophysiology of pemphigus and pemphigoid have led to the development of molecules which target specific pathways involved in induction and perpetuation of disease. In this review, we outline the novel therapeutic strategies including B-cell depletion, T-regulatory cell repletion, cell signalling inhibitors and small molecular inhibitors, inhibitory monoclonal antibodies, as well as complement inhibition. We additionally review their current level of clinical evidence. We lastly review therapeutics targets gleaned from the experimental epidermolysis bullosa acquisita mouse model. These emerging treatments offer an exciting progression from basic science discoveries that have the potential to transform the treatment paradigm in autoimmune blistering diseases., (© 2019 European Academy of Dermatology and Venereology.)

Eosinophils are seen in a number of dermatologic conditions. While the extent of their function in these diseases remains to be fully elucidated, pathogenic activity in bullous pemphigoid suggests a more significant role than previously thought. Several dermatoses have a fairly characteristic histologic morphology of eosinophil infiltration. We hypothesized that epidermal expression of eotaxins and TSLP would differ by disease, perhaps explaining the different histologic morphologies. We performed a retrospective study of eosinophil rich dermatoses to perform immunohistochemistry. We collected 49 specimens composed of bullous pemphigoid (n = 15), atopic dermatitis (n = 12), drug rash (n = 8), arthropod assault (n = 5), and non-bullous pemphigoid eosinophilic spongiosis (n = 5). We used lichen planus (n = 4) as a control for lymphocyte-mediated inflammation. TSLP was diffusely expressed in all epidermal samples, whereas eotaxins demonstrated a weaker staining. Eotaxins and TSLP demonstrated a gradient between basal and spinous keratinocytes. The correlation between overall basal keratinocyte and spinous keratinocyte staining of eotaxins and TSLP with the number of eosinophils demonstrated a significant correlation between eotaxin-1 (R = 0.404, P = 0.004), eotaxin-2 (R = 0.576, P < 0.001), and eotaxin-3 (R = 0.512, P < 0.001), but not TSLP (R = 0.164, P = 0.251). These remained significant after correcting for multiple comparisons. While we were unable to detect significant differences in epidermal expression of eotaxins and TSLP in various eosinophil rich dermatoses, we identified a significant correlation of spinous keratinocyte eotaxin staining with tissue eosinophilia. Our identification of a correlation of spinous keratinocyte eotaxin staining with tissue eosinophilia may provide insight into local eosinophil chemotaxis.

Background: Autoimmune blistering diseases are a group of severe mucocutaneous conditions that typically require the use of prolonged corticosteroids and immunosuppression. Properly managing associated comorbidities is an integral part of these patients' care. The frequency of gastrointestinal symptoms, particularly gastrointestinal bleeding in these patients, is not known. Likewise, the effect of diet on disease is unknown., Objective: To determine the incidence of gastrointestinal comorbidities and the role of diet in patients with autoimmune blistering disease., Methods: We distributed an e-survey to patients with autoimmune blistering disease utilizing the International Pemphigus and Pemphigoid Foundation's listserv. The incidence of gastrointestinal symptoms and gastrointestinal bleeding were recorded, as were foods avoided and those noted to be beneficial in patients' disease. Historical incidences in the general population were used as controls., Results: A total of 200 responses were collected. 30.3% of patients experienced gastroesophageal reflux following treatment of their autoimmune blistering disease, with 51.7% utilizing some form of gastrointestinal symptomatic treatment. The incidence of gastrointestinal bleeding following an autoimmune blistering diagnosis was 2.1%, which remained significant despite correction for non-steroidal anti-inflammatory use (NSAID), but not corticosteroid use. 65.2% of patients reported dietary limitations because of their autoimmune blistering disease. Significant intolerances after correction for multiple comparisons included alcohol, citrus and spicy foods. Greater than 10% of patients reported improvements in their disease with vegetables and dairy., Conclusions: Gastrointestinal comorbidities are common in patients with autoimmune blistering diseases, with gastrointestinal bleeding occurring in 2.1% of patients following a diagnosis of autoimmune blistering disease. While further work is needed to determine the relative risk of routine gastrointestinal prophylaxis in this population, gastrointestinal bleeding prophylaxis should be considered in patients receiving corticosteroids, particularly those taking NSAIDs. Dietary limitations are additionally frequent in this population. Patients should be cautious of alcohol, citrus and spicy foods., (© 2019 European Academy of Dermatology and Venereology.)

Epidermolysis bullosa acquisita is a rare autoimmune blistering disease which results in vesicle and bullae formation on the skin and erosions on the mucous membranes. EBA is mediated by autoantibodies to collagen VII. Clinically, it can present with numerous phenotypes, though the most common are the mechanobullous and inflammatory variants. Patients with mechanobullous EBA develop non-inflammatory bullae and erosions at sites of trauma while patients with the non-mechanobullous type develop inflammatory lesions which often mimic other blistering conditions including bullous pemphigoid, linear IgA bullous disease, and mucous membrane pemphigoid. Diagnosis is established by having a consistent clinical presentation, DIF, and autoantibodies against collagen VII. In apparent "seronegative" patients, the diagnosis is challenging due to the need for confirmatory tests which are often not routinely accessible outside of the specialized center. In light of EBA's rarity, and lack of any randomized controlled trials, treatment guidelines rely on the small case series presented in the literature. There has been variable success utilizing the arsenal of immunosuppressants and biologics. Development of experimental murine models has facilitated a deeper understanding of EBA's pathogenesis and allows for preclinical testing of numerous novel drug targets predominantly targeting inhibition of neutrophil activation. We herein review the presentation, diagnosis, treatments, and future avenues of research in EBA., (Copyright © 2019. Published by Elsevier B.V.)

Bullous pemphigoid and pemphigus constitute two major autoimmune blistering diseases (AIBD) with complicated disease pathomechanisms involving a multitude of cytokines and immunological pathways. The purpose of our literature review of the cytokines and chemokines involved in these AIBDs was to allow for a meta-analysis of studies detailing differential cytokine and chemokine changes in these conditions. Elucidation of inflammatory pathways could lead to more targeted therapies, several of which specific monoclonal antibodies already exist and are used safely for other autoimmune diseases. A systematic review of the Pubmed/Medline database was performed for articles characterizing cytokines/chemokines involved in BP and pemphigus. Further, a meta-analysis was carried out using standardized methods, including assessment for heterogeneity. The results of our analysis demonstrated numerous inflammatory alterations in these AIBDs. Significant alterations included serum levels of IL-5, IL-6, IL-8, IL-17, CCL-17, and CCL-26 in patients with BP, and increased blister fluids levels of IL-5, IL-6, IL-8, CCL11, and TNF-α. Blister fluid levels of IL-1α are decreased in BP. In pemphigus, we identified significantly increased serum levels of IL-10, IL-17, and CCL17. We have additionally summarized all studies excluded from meta-analysis to provide a comprehensive summary of cytokine/chemokine alterations in these two conditions., (Copyright © 2019 Elsevier B.V. All rights reserved.)