iNOS deficiency aggravates DNFB-induced atopic dermatitis in mice.

Abstract

BACKGROUND: Atopic dermatitis (AD) is the most common chronic inflammatory skin disease. Its pathogenesis is closely related to the imbalance of immune homeostasis regulation. Accumulating evidence demonstrated that nitric oxide (NO) serves a critical role in modulating skin immune homeostasis during the development of multiple inflammatory skin diseases. NO is mainly synthesized by inducible nitric oxide synthase (iNOS); however, the mechanism underlying iNOS in AD has not been fully elucidated yet. The present study aimed to investigate the specific mechanisms by which iNOS regulates the development of AD. METHODS: We first detected the expression of iNOS in AD lesions using immunofluorescence staining. Subsequently, we detected the expression of inflammatory cytokines and chemokines using pathological staining and qRT-PCR; and assessed the infiltration of immune cells by flow cytometry and immunofluorescence staining. We utilized RNA-seq to initially explore the mechanism by which iNOS regulates AD progression. Finally, we used IL-17 A combined with TNF-α to stimulate mouse keratinocytes and fibroblasts to further validate the in vivo results. RESULTS: Our results showed that iNOS expression was significantly upregulated in AD lesions, and iNOS deficiency significantly promoted the AD-like inflammation. Subsequently, the results of RNA-seq and qRT-PCR demonstrated that iNOS deficiency significantly promoted the expression of vital effector molecules of "IL-17 signaling pathway". At the same time, the proportion of IL-17 AT cells was significantly increased in skin lesions of iNOS-deficient mice. Finally, iNOS deficiency significantly up-regulated the expression levels of multiple cytokines in keratinocytes and fibroblasts. CONCLUSION: iNOS deficiency exacerbated AD-like inflammatory responses, which may be associated with increased IL-17 signaling activity.