Epidermal growth factor receptor/mitogen-activated kinase inhibitor treatment induces a distinct inflammatory hair follicle response that includes collapse of immune privilege.

BACKGROUND: Inhibitors of epidermal growth factor receptor (EGFRi) or mitogen-activated kinase (MEKi) induce a folliculitis in 75-90% of patients, the pathobiology of which remains insufficiently understood. OBJECTIVES: To characterize changes in the skin immune status and global transcriptional profile of patients treated with EGFRi; to investigate whether EGFRi affects the hair follicle's (HF) immune privilege (IP); and to identify early proinflammatory signals induced by EGFRi/MEKi in human scalp HFs ex vivo. METHODS: Scalp biopsies were taken from patients exhibiting folliculitis treated long term with EGFRi ('chronic EGFRi' group, n = 9) vs. healthy scalp skin (n = 9) and patients prior to commencing EGFRi treatment and after 2 weeks of EGFRi therapy ('acute EGFRi' group, n = 5). Healthy organ-cultured scalp HFs were exposed to an EGFRi (erlotinib, n = 5) or a MEKi (cobimetinib, n = 5). Samples were assessed by quantitative immunohistomorphometry, RNA sequencing (RNAseq) and in situ hybridization. RESULTS: The 'chronic EGFRi' group showed CD8+ T-cell infiltration of the bulge alongside a partial collapse of the HF's IP, evidenced by upregulated major histocompatibility complex (MHC) class I, ß2-microglobulin (B2 M) and MHC class II, and decreased transforming growth factor-ß1 protein expression. Healthy HFs treated with EGFRi/MEKi ex vivo also showed partial HF IP collapse and increased transcription of human leucocyte antigen (HLA)-A, HLA-DR and B2 M transcripts. RNAseq analysis showed increased transcription of chemokines (CXCL1, CXCL13, CCL18, CCL3, CCL7) and interleukin (IL)-26 in biopsies from the 'chronic EGFRi' cohort, as well as increased IL-33 and decreased IL-37 expression in HF biopsies from the 'acute EGFRi' group and in organ-cultured HFs. CONCLUSIONS: The data show that EGFRi/MEKi compromise the physiological IP of human scalp HFs and suggest that future clinical management of EGFRi/MEKi-induced folliculitis requires HF IP protection and inhibition of IL-33.

About 75­90% of people with cancer who are treated with drugs called EGFR inhibitors (EGFRi) and MEK inhibitors (MEKi) will get a skin condition called folliculitis. This is where the hair follicles become inflamed. Despite this, the reasons why some patients develop this are not well understood. In this study, we had three goals. We wanted to understand how these medications alter the skin's immune response and genetic processes. We also wished to determine the impact of the medications on the immune protection of hair follicles. Finally, we wanted to find early signs of inflammation in hair follicles caused by the medications. We studied scalp samples from people who got folliculitis after long-term EGFRi treatment and compared them to samples of healthy scalp skin. We also examined patients before and after they began EGFRi treatment. In the lab, we exposed healthy hair follicles to an EGFRi called 'erlotinib' or a MEKi called 'cobimetinib'. We then carried out detailed imaging and genetic analyses. We found that long-term treatment with EGFRi increased certain immune cells (called CD8+ T cells) in the hair follicle area. This led to a breakdown in the immune protection around hair follicles. A similar breakdown was found in lab-treated healthy follicles. Genetic changes linked to inflammation were also found. Our findings suggest that EGFRi and MEKi treatments could affect the natural immune defence of hair follicles in the scalp and cause folliculitis. Protecting the immune system and controlling inflammation might be the key to treating people with these drug-related skin conditions.

High-fat diet induces a predisposition to follicular hyperkeratosis and neutrophilic folliculitis in mice.

BACKGROUND: Neutrophilic folliculitis is an inflammatory condition of hair follicles. In some neutrophilic folliculitis, such as in patients with acne and hidradenitis suppurativa, follicular hyperkeratosis is also observed. Neutrophilic folliculitis is often induced and/or exacerbated by a high-fat diet (HFD). However, the molecular mechanisms by which an HFD affects neutrophilic folliculitis are not fully understood. OBJECTIVE: Our aim was to elucidate how an HFD promotes the development of neutrophilic folliculitis. METHODS: Mice were fed an HFD, and their skin was subjected to histologic, RNA sequencing, and imaging mass spectrometry analyses. To examine the effect of an HFD on neutrophil accumulation around the hair follicles, phorbol 12-myristate 13-acetate (PMA) was used as an irritant to the skin. RESULTS: Histologic analysis revealed follicular hyperkeratosis in the skin of HFD-fed mice. RNA sequencing analysis showed that genes related to keratinization, especially in upper hair follicular keratinocytes, were significantly upregulated in HFD-fed mice. Application of PMA to the skin induced neutrophilic folliculitis in HFD-fed mice but not in mice fed a normal diet. Accumulation of neutrophils in the skin and around hair follicles was dependent on CXCR2 signaling, and CXCL1 (a CXCR2 ligand) was produced mainly by hair follicular keratinocytes. Imaging mass spectrometry analysis revealed an increase in fatty acids in the skin of HFD-fed mice. Application of these fatty acids to the skin induced follicular hyperkeratosis and caused PMA-induced neutrophilic folliculitis even in mice fed a normal diet. CONCLUSION: An HFD can facilitate the development of neutrophilic folliculitis with the induction of hyperkeratosis of hair follicles and increased neutrophil infiltration around the hair follicles via CXCR2 signaling.

Immunophenotyping comparison of inflammatory cells between Malassezia folliculitis and pityriasis versicolor lesions.

Immunophenotyping of inflammatory dermal infiltrates in Malassezia folliculitis (MF) and pityriasis versicolor (PV) lesions is less reported. Immunohistochemistry was performed on 21 MF lesions, 10 PV lesions, and 10 control skin. CD3+, CD4+, CD8+, CD20+, CD68+, and CD117+ cells were increased in MF compared with PV and normal skin (P < 0.01-0.05), while CD3+, CD4+, and CD20+ cells were higher in PV than in normal skin (P < 0.05). Dermal CD1a+ cells were higher only in PV (P < 0.05). Although both cellular and humoral immune responses are involved in pathogenesis of MF and PV, their difference may contribute to clinicopathological discrepancy between two disorders. LAY SUMMARY: Malassezia folliculitis and pityriasis versicolor are common Malassezia-induced superficial mycoses. Their clinicopathological discrepancy may be due to the difference of cellular and humoral immune responses.

A Case of Eosinophilic Pustular Folliculitis Associated With Herpes Zoster.

ABSTRACT: Patients with eosinophilic pustular folliculitis (EPF), a sterile eosinophilic infiltration of hair follicles, often present with papulopustules that tend to form annular plaques. Histopathologic examination revealed eosinophilic infiltration around the pilosebaceous units and eosinophilic microabscess formation. Although the pathogenesis of EPF is unknown, T-helper type 2 immune responses were suggested to be important based on their stimulating effect on the sebaceous glands. Here, we report the first case of EPF associated with herpes zoster, indicating that herpes zoster and EPF are correlated with T-helper type 2 immune responses.

Eosinophilic dermatoses.

Eosinophilic dermatoses are a heterogeneous group of diseases, characterized by an eosinophil-rich infiltrate and/or degranulation of eosinophils. Blood eosinophilia may be an associated feature. Typical, albeit not specific histological findings include 'flame figures', which are caused by the accumulation of cationic proteins released by eosinophils and subsequent collagen denaturation. "Classic" eosinophilic dermatoses include eosinophilic cellulitis (Wells syndrome), granuloma faciale, eosinophilic fasciitis (Shulman syndrome) and eosinophilic folliculitis (Ofuji disease). In addition, there is a multitude of skin diseases that present with varying degrees of eosinophilic infiltration. These include atopic dermatitis, bullous pemphigoid, urticaria, allergic contact dermatitis, prurigo nodularis, arthropod bite reaction, parasitic infections, and drug hypersensitivity. Even though these disorders share a common characteristic (tissue eosinophilia), they differ greatly in their clinical presentation.

Inflammasome Activation Characterizes Lesional Skin of Folliculitis Decalvans.

Folliculitis decalvans (FD) is a chronic inflammatory disease leading to scarring alopecia with poorly defined pathogenesis. The aim of this study was to investigate the expression of markers associated with the activation of innate immune signals, such as inflammasome (NALP1 and NALP3), interleukin (IL)-1ß and IL-8 and type I interferon (MxA). A retrospective monocentric study was conducted and included 17 patients with FD with available biopsies. Disease activity (stable vs. active) was defined clinically and histologically. Immunostaining was performed using antibodies directed against NALP1, NALP3, IL-1ß, IL-8, and MxA on FD skin biopsies. Results were compared with normal controls and lichen planopilaris. Eleven patients had active disease and 6 had stable disease. NALP1, NALP3, and IL-1ß expression were significantly increased in hair follicles in FD compared with controls and lichen planopilaris. This study highlights the predominant immune signal associated with inflammasome activation in FD, suggesting the use of IL-1ß blockade in FD.

A case of refractory chronic neutrophilic pustular folliculitis treated with adalimumab.

Neutrophilic folliculitis is an often overlooked chronic condition characterized by a monomorphic eruption of "sterile" papulopustules. Neutrophilic folliculitis is often refractory to conventional treatment with topical and systemic antibiotics or isotretinoin. We report a case of severe pustular neutrophilic folliculitis successfully treated with the tumor necrosis factor-alpha inhibitor adalimumab.

Malassezia infections: a medical conundrum.

Malassezia yeasts have long been considered commensal fungi, unable to elicit significant damage. However, they have been associated with a diversity of cutaneous diseases, namely pityriasis versicolor, Malassezia folliculitis, seborrheic dermatitis, atopic dermatitis, psoriasis, and confluent and reticulate papillomatosis. Several hypotheses have been proposed to explain the pathogenic mechanisms of these fungi, but none have been confirmed. More recently, such organisms have been increasingly isolated from bloodstream infections raising serious concern about these fungi. Given the difficulty to culture these yeasts to proceed with speciation and antimicrobial susceptibility tests, such procedures are most often not performed and the cutaneous infections are treated empirically. The recurring nature of superficial skin infections and the potential threat of systemic infections raise the need of faster and more sensitive techniques to achieve isolation, identification, and antimicrobial susceptibility profile. This article reviews and discusses the latest available data concerning Malassezia infections and recent developments about diagnostic methods, virulence mechanisms, and susceptibility testing.

Indomethacin inhibits eosinophil migration to prostaglandin D2 : therapeutic potential of CRTH2 desensitization for eosinophilic pustular folliculitis.

Indomethacin is a cyclo-oxygenase inhibitor, and shows therapeutic potential for various eosinophilic skin diseases, particularly eosinophilic pustular folliculitis. One of the unique characteristics of indomethacin is that, unlike other non-steroidal anti-inflammatory drugs, it is a potent agonist of chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2), a receptor for prostaglandin D2 (PGD2 ). This study investigated the pharmacological actions of indomethacin on eosinophil migration to clarify the actual mechanisms underlying the therapeutic effects of indomethacin on eosinophilic pustular folliculitis. Eosinophils exhibited chemokinetic and chemotactic responses to both PGD2 and indomethacin through CRTH2 receptors. Pre-treatment of eosinophils with indomethacin greatly inhibited eosinophil migration to PGD2 and, to a much lesser extent, to eotaxin (CCL11); these effects could be mediated by homologous and heterologous desensitization of eosinophil CRTH2 and CCR3, respectively, by agonistic effects of indomethacin on CRTH2. Indomethacin also cancelled a priming effect of Δ(12) -PGJ2 , a plasma metabolite of PGD2 , on eosinophil chemotaxis to eotaxin. Indomethacin down-modulated cell surface expression of both CRTH2 and CCR3. Hair follicle epithelium and epidermal keratinocytes around eosinophilic pustules together with the eccrine apparatus of palmoplantar lesions of eosinophilic pustular folliculitis were immunohistochemically positive for lipocalin-type PGD synthase. Indomethacin may exert therapeutic effects against eosinophilic skin diseases in which PGD2 -CRTH2 signals play major roles by reducing eosinophil responses to PGD2 .

Bilaterally symmetrical alopecia with reticulated hyperpigmentation: a manifestation of cutaneous lupus erythematosus in a dog with systemic lupus erythematosus.

An adult castrated male Doberman Pinscher was presented with a 6-month history of well-demarcated alopecic patches with reticulated hyperpigmentation and fine peripheral scaling on the axillae, thorax, abdomen, inguinal region, and thighs. The dog later developed hyperthermia, lethargy, apparent joint pain, peripheral lymphadenomegaly, vomiting, and diarrhea. Relevant laboratory tests results included anemia, thrombocytopenia, proteinuria, and an elevated antinuclear antibodies serum titer. Histologically, skin biopsy specimens had a lymphocyte-rich interface dermatitis and interface mural folliculitis ending in follicular destruction. Altogether, these signs were consistent with a unique alopecic variant of chronic cutaneous lupus erythematosus, eventually associated with the development of systemic lupus erythematosus. This rare form of chronic cutaneous lupus needs to be added to the expanding list of lymphocyte-mediated autoimmune alopecias in dogs.

Herpes folliculitis masquerading as cutaneous lymphoma.

Herpes virus infections presenting as folliculitis are uncommon. We describe a 48-year-old white man with a distant history of a childhood gastric lymphoma and renal cell carcinoma presenting with an itchy eruption. He was concerned about recurrence. A punch biopsy revealed interface dermatitis with a dense atypical superficial and deep perivascular and periadnexal lymphohistiocytic infiltrate with occasional eosinophils extending to the subcutis, with destruction of vessel walls. It was composed of predominantly CD3-positive lymphocytes with scattered CD56-positive cells and CD20-positive cells, concerning for lymphoma. A T-cell gene rearrangement study was negative. Deeper sections uncovered multinucleated giant keratinocytes in the follicular epithelium of 1 hair follicle, consistent with herpes folliculitis. Cutaneous herpes infections can exhibit several variable clinical and histopathological features. Knowledge of alternative presentations of herpes infections, histological clues to the presence of herpes infections, and careful clinicopathological correlation are necessary to differentiate herpes infections from cutaneous lymphomas and other inflammatory dermatoses.

PGD2 induces eotaxin-3 via PPARγ from sebocytes: a possible pathogenesis of eosinophilic pustular folliculitis.

BACKGROUND: Eosinophilic pustular folliculitis (EPF) is a chronic intractable pruritic dermatosis characterized by massive eosinophil infiltrates involving the pilosebaceous units. Recently, EPF has been regarded as an important clinical marker of HIV infection, and its prevalence is increasing in number. The precise mechanism by which eosinophils infiltrate into the pilosebaceous units remains largely unknown. Given that indomethacin, a COX inhibitor, can be successfully used to treat patients with EPF, we can assume that COX metabolites such as prostaglandins (PGs) are involved in the etiology of EPF. OBJECTIVE: To determine the involvement of PGs in the pathogenesis of EPF. METHODS: We performed immunostaining for PG synthases in EPF skin lesions. We examined the effect of PGD(2) on induction of eotaxin, a chemoattractant for eosinophils, in human keratinocytes, fibroblasts, and sebocytes and sought to identify its responsible receptor. RESULTS: Hematopoietic PGD synthase was detected mainly in infiltrating inflammatory cells in EPF lesions, implying that PGD(2) was produced in the lesions. In addition, PGD(2) and its immediate metabolite 15-deoxy-Δ 12,14-PGJ(2) (15d-PGJ(2)) induced sebocytes to produce eotaxin-3 via peroxisome proliferator-activated receptor gamma. Consistent with the above findings, eotaxin-3 expression was immunohistochemically intensified in sebaceous glands of the EPF lesions. CONCLUSION: The PGD(2)/PGJ(2)-peroxisome proliferator-activated receptor gamma pathway induces eotaxin production from sebocytes, which may explain the massive eosinophil infiltrates observed around pilosebaceous units in EPF.

[Verification of the hygienic hypothesis by evaluating the regional incidence of eosinophilic pustular folliculitis].

Eosinophilic pustular folliculitis (EPF) is a disorder associated with a high expression of interleukin-5 by T helper 2 cells. Treatment involving T helper 1 (Th1) modulation has been shown to be effective. We report that the occurrence of Bowen's disease in the medical care zone of the University of Occupational and Environmental Health in the Kitakyushu industrial area is more frequent in Yahatahigashi-ku, Yahatanishi-ku, and Wakamatsu-ku than in Tobata-ku, Kokurakita-ku, and Kokuraminamiku. We also show that these cases are more common in the regions with steel- and coal-related industries, which is suggestive of a higher rate of Th1 modulation associated with these occupations. Similarly, the incidence of EPF per unit population was found to be high in Tobata-ku and low in Yahatahigashi-ku, which indicates that EPF is a typical disease of hygiene hypothesis.

Pruritic papular eruption and eosinophilic folliculitis associated with human immunodeficiency virus (HIV) infection: a histopathological and immunohistochemical comparative study.

BACKGROUND: Among the papular-pruriginous dermatoses related to human immunodeficiency (HIV) infection, two entities remain poorly differentiated leading to confusion in their diagnosis: HIV-related pruritic papular eruption (HIV-PPE or prurigo) and eosinophilic folliculitis (HIV-EF). OBJECTIVE: To establish histopathological and immunohistochemical parameters to differentiate between two conditions associated with HIV infection, the pruritic papular eruption (HIV-PPE) and eosinophilic folliculitis (HIV-EF). METHODS: Clinically typical HIV-PPE (18 cases) and HIV-EF (10 cases) cases were compared with each other in terms of the following topics: clinical and laboratory features (gender, age, CD4+ cell and eosinophil count), histopathological features (hematoxylin-eosin and toluidine blue staining) and immunohistochemical features (anti-CD1a, anti-CD4, anti-CD7, anti-CD8, anti-CD15, anti-CD20, anti-CD30, anti-CD68/macrophage and anti-S-100 reactions). RESULTS: Among the HIV-EF patients, we found an intense perivascular and diffuse inflammatory infiltration compared with those patients with HIV-PPE. The tissue mast cell count by toluidine staining was higher in the HIV-EF patients, who also presented higher expression levels of CD15 (for eosinophils), CD4 (T helper), and CD7 (pan-T lymphocytes) than the HIV-PPE patients. LIMITATIONS: Only quantitative differences and not qualitative differences were found. CONCLUSIONS: These data indicate that HIV-related PPE and EF could possibly be differentiated by histopathological and immunohistochemical findings in addition to clinical characteristics. In fact, these two inflammatory manifestations could be within the spectrum of the same disease because only quantitative, and not qualitative, differences were found.

The role of inflammation and immunity in the pathogenesis of androgenetic alopecia.

BACKGROUND: Female pattern hair loss affects many women; its pathogenetic basis has been held to be similar to men with common baldness. OBJECTIVE: The objective of this study was to determine the role of immunity and inflammation in androgenetic alopecia in women and modulate therapy according to inflammatory and immunoreactant profiles. MATERIALS AND METHODS: 52 women with androgenetic alopecia (AA) underwent scalp biopsies for routine light microscopic assessment and direct immunofluroescent studies. In 18 patients, serologic assessment for antibodies to androgen receptor, estrogen receptor and cytokeratin 15 was conducted. RESULTS: A lymphocytic folliculitis targeting the bulge epithelium was observed in many cases. Thirty-three of 52 female patients had significant deposits of IgM within the epidermal basement membrane zone typically accompanied by components of complement activation. The severity of changes light microscopically were more apparent in the positive immunoreactant group. Biopsies from men with androgenetic alopecia showed a similar pattern of inflammation and immunoreactant deposition. Serologic assessment for antibodies to androgen receptor, estrogen receptor or cytokeratin 15 were negative. Combined modality therapy with minocycline and topical steroids along with red light produced consistent good results in the positive immunoreactant group compared to the negative immunoreactant group. CONCLUSION: A lymphocytic microfolliculitis targeting the bulge epithelium along with deposits of epithelial basement membrane zone immunoreactants are frequent findings in androgenetic alopecia and could point toward an immunologically driven trigger. Cases showing a positive immunoreactant profile respond well to combined modality therapy compared to those with a negative result.

Clinical features and treatment of epidermal growth factor inhibitor-related late-phase papulopustular rash.

Papulopustular rash, an acneiform rash, appears on the seborrheic region during the first to second week of treatment with an epidermal growth factor receptor inhibitor (EGFRi). The rash gradually disappears after the fourth week; however, it persists or newly develops in other regions during EGFRi treatment. Because Staphylococcus aureus is frequently isolated from late-phase papulopustular rash, we assessed the incidence of bacterial infection and treatment outcomes of patients with late-phase papulopustular rash. Sixty-four cases treated with an EGFRi over 4 weeks who presented with papulopustular rash were assessed retrospectively. The median duration of EGFR inhibitor treatment was 5 months. Grade 2 and 3 papulopustular rash was observed in 47 and eight cases, respectively. Bacterial culture was performed in 51 cases, 50 of which yielded positive results: methicillin-sensitive S. aureus in 29, methicillin-resistant S. aureus in 14, Staphylococcus species in five, Pseudomonas aeruginosa in three, and other in four cases. Of the S. aureus isolates, 42% were resistant to minocycline and 40% to levofloxacin. After treatment with topical and/or oral antibiotics without topical corticosteroids, the papulopustular rash rapidly improved by an average of 2.9 ± 3.4 weeks. However, use of a combination of antibiotics and a topical corticosteroid prolonged the recovery period to an average of 18.9 ± 11.4 weeks. In conclusion, folliculitis that develops over 4 weeks after the initiation of EGFRi treatment is typically caused by staphylococcal infection. Bacterial culture is necessary due to the high rate of antibiotic resistance. It is important to distinguish late- from early-phase papulopustular rash and to treat using different approaches.

Efficacy and Safety of Baricitinib Combined With Topical Corticosteroids for Treatment of Moderate to Severe Atopic Dermatitis: A Randomized Clinical Trial.

Importance: Baricitinib, an oral selective Janus kinase 1 and 2 inhibitor, effectively reduced disease severity in moderate to severe atopic dermatitis (AD) in 2 phase 3 monotherapy studies. Objective: To assess the efficacy and safety of 4 mg and 2 mg of baricitinib in combination with background topical corticosteroid (TCS) therapy in adults with moderate to severe AD who previously had an inadequate response to TCS therapy. Design, Setting, and Participants: This double-blind, placebo-controlled, phase 3 randomized clinical trial, BREEZE-AD7 (Study of Baricitinib [LY3009104] in Combination With Topical Corticosteroids in Adults With Moderate to Severe Atopic Dermatitis) was conducted from November 16, 2018, to August 22, 2019, at 68 centers across 10 countries in Asia, Australia, Europe, and South America. Patients 18 years or older with moderate to severe AD and an inadequate response to TCSs were included. After completing the study, patients were followed up for up to 4 weeks or enrolled in a long-term extension study. Interventions: Patients were randomly assigned (1:1:1) to receive 2 mg of baricitinib once daily (n = 109), 4 mg of baricitinib once daily (n = 111), or placebo (n = 109) for 16 weeks. The use of low-to-moderate potency TCSs was allowed. Main Outcomes and Measures: The primary end point was the proportion of patients achieving a validated Investigator Global Assessment for Atopic Dermatitis (vIGA-AD) score of 0 (clear) or 1 (almost clear), with a 2-point or greater improvement from baseline at week 16. Results: Among 329 patients (mean [SD] age, 33.8 [12.4] years; 216 [66%] male), at week 16, a vIGA-AD score of 0 (clear) or 1 (almost clear) was achieved by 34 patients (31%) receiving 4 mg of baricitinib and 26 (24%) receiving 2 mg of baricitinib compared with 16 (15%) receiving placebo (odds ratio vs placebo, 2.8 [95% CI, 1.4-5.6]; P = .004 for the 4-mg group; 1.9 [95% CI, 0.9-3.9]; P = .08 for the 2-mg group). Treatment-emergent adverse events were reported in 64 of 111 patients (58%) in the 4-mg group, 61 of 109 patients (56%) in the 2-mg group, and 41 of 108 patients (38%) in the placebo group. Serious adverse events were reported in 4 patients (4%) in the 4-mg group, 2 (2%) in the 2-mg group, and 4 (4%) in the placebo group. The most common adverse events were nasopharyngitis, upper respiratory tract infections, and folliculitis. Conclusions and Relevance: A dose of 4 mg of baricitinib in combination with background TCS therapy significantly improved the signs and symptoms of moderate to severe AD, with a safety profile consistent with previous studies of baricitinib in AD. Trial Registration: ClinicalTrials.gov Identifier: NCT03733301.