In Situ Non‐Invasive Imaging of Neutrophil Myeloperoxidase and Skin Reactive Oxygen Species in Experimental Murine Atopic Dermatitis

Abstract

AbstractNeutrophils play a key role in the innate immune inflammatory response, notably through the release of the myeloperoxidase enzyme from azurophilic granules, locally generating reactive oxygen species. Although short‐lived, these reactive oxygen species are directly involved in local tissue damage in response to microbial intrusion. Neutrophil‐derived myeloperoxidase has been reported as an important factor in the elicitation of atopic dermatitis and is considered a potential target and biomarker. This study describes the use of in situ imaging techniques comprising both chemiluminescent resonance energy‐transfer and ratiometric fluorescent microtattoos to locally and non‐invasively image myeloperoxidase activity and skin reactive oxygen species in a murine model of calcipotriol‐induced atopic dermatitis. Using neutrophil depletion to assess granulocyte contribution to the observed imaging signals, the non‐invasive longitudinal data are found to correlate with endpoint biochemical activity assays for both myeloperoxidase and reactive oxygen species by‐products, as well as with immunohistochemical analysis.