RESUMO
Prurigo nodularis is a highly pruritic and hyperplastic chronic dermatosis with unknown pathogenesis. Many pruritogenic mediators, including nerve growth factor, interleukin (IL)-31, thymic stromal lymphopoietin, and endothelin-1, are implicated in chronic itch and inflammation. This study investigated the mRNA levels and immunoreactivity of the nerve growth factor, IL-31, thymic stromal lymphopoietin, and endothelin axes in both lesional and perilesional skin in prurigo nodularis by using quantitative real-time PCR and immunohistochemistry studies. The nerve growth factor high-affinity receptor tyrosine kinase receptor A was upregulated while the low affinity receptor p75 neurotrophin receptor was downregulated in prurigo nodularis lesions. Downregulated expression of IL-31/IL-31 receptor A and endothelin-3/endothelin receptor B and upregulation of thymic stromal lymphopoietin receptor were found in prurigo nodularis lesions. Aberrant expression of nerve growth factor, IL-31, thymic stromal lymphopoietin and endothelin axes was found in prurigo nodularis lesions, especially in the epidermis, indicating the importance of keratinocytes in prurigo nodularis pathogenesis.
Assuntos
Epiderme/metabolismo , Queratinócitos/metabolismo , Prurigo/genética , Prurigo/metabolismo , Adulto , Citocinas/genética , Citocinas/metabolismo , Regulação para Baixo , Endotelina-3/genética , Endotelina-3/metabolismo , Feminino , Expressão Gênica , Humanos , Hipersensibilidade/complicações , Hipersensibilidade/genética , Hipersensibilidade/metabolismo , Subunidade alfa de Receptor de Interleucina-7/genética , Subunidade alfa de Receptor de Interleucina-7/metabolismo , Interleucinas/genética , Interleucinas/metabolismo , Masculino , Pessoa de Meia-Idade , Fator de Crescimento Neural/genética , Fator de Crescimento Neural/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Prurigo/complicações , RNA Mensageiro/metabolismo , Receptor de Endotelina B/genética , Receptor de Endotelina B/metabolismo , Receptor trkA/genética , Receptor trkA/metabolismo , Receptores de Citocinas/genética , Receptores de Citocinas/metabolismo , Receptores de Interleucina/genética , Receptores de Interleucina/metabolismo , Receptores de Fator de Crescimento Neural/genética , Receptores de Fator de Crescimento Neural/metabolismo , Regulação para Cima , Linfopoietina do Estroma do TimoRESUMO
Pruritus is a common symptom of several skin diseases, both inflammatory and neoplastic. Pruritus might have a tremendous impact on patients' quality of life and strongly interfere with sleep, social, and work activities. We review the role of type-2 inflammation and immunity in the pathogenesis of chronic pruritic conditions of the skin. Type 2 cytokines, including IL-4, IL-13, thymic stromal lymphopoietin, periostin, IL-31, IL-25, and IL-33 are released by mast cells, innate lymphoid cells 2, keratinocytes, and type 2 T lymphocytes, and are master regulators of chronic itch. These cytokines might act as direct pruritogen on primary sensory neurons (pruriceptors) or alter the sensitivity to other itch mediators Type 2 inflammation- and immunity-dominated skin diseases, including atopic dermatitis, prurigo nodularis, bullous pemphigoid, scabies, parasitic diseases, urticaria, and Sézary syndrome are indeed conditions associated with most severe pruritus. In contrast, in other skin diseases, such as scleroderma, lupus erythematosus, hidradenitis suppurativa, and acne, type 2 inflammation is less represented, and pruritus is milder or variable. Th2 inflammation and immunity evolved to protect against parasites, and thus, the scratching response evoked by pruritus might have developed to alert about the presence and to remove parasites from the skin surface.