Biomarkers of in vivo fluorescence imaging in allergic airway inflammation

• Fluorescence imaging of biomarkers performs a novel method for monitoring of lung airway inflammation in asthma.
• MMPs, cathepsins, selectins, FR-β, nanoparticles and Siglec-F are biomarkers we have known so far.
• None of these biomarkers are without problems and limitations, and Siglec-F is the most specific for asthma.

Airway inflammation is a central component of the manifestation of asthma but is relatively inaccessible to study. Current imaging techniques such as X-ray CT, MRI, and PET, have advanced noninvasive research on pulmonary diseases. However, these techniques mainly facilitate the anatomical or structural assessment of the diseased lung and/or typically use radioactive agents. In vivo fluorescence imaging is a novel method for noninvasive, real-time, and specific monitoring of lung airway inflammation, which is particularly important to gain a further understanding asthma. Compared to conventional techniques, fluorescent imaging has the advantages of rapid feedback, as well as high sensitivity and resolution. Recently, there has been an increase in the identification of biomarkers, including matrix metalloproteinases, cathepsins, selectins, folate receptor-beta, nanoparticles, as well as sialic acid-binding immunoglobulin-like lectin-F to assess the level of airway inflammation in asthma. Recent advances in our understanding of these biomarkers as molecular probes for in vivo imaging are discussed in this review.