The semaphorins are a family of soluble and membrane associated proteins characterized by a conserved “sema” domain. They were originally described as axonal growth and guidance proteins required to guide neuronal axons to the right targets. Today, semaphorins are known to possess pleiotropic and important functions in several physiological and pathogenic processes, including heart development, vascular growth, tumor progression, immune cell regulation, angiogenesis and vasculogenesis^1,2.

To date more than 20 types of semaphorin proteins have been identified. Semaphorin-7A, also known as CD108, promotes olfactory bulb axon outgrowth in the nervous system. It is also required for the appropriate formation of the lateral olfactory tract during embryonic development¹.

Some of semaphorin-7A functions are mediated through β1-integrins and the transmembrane protein plexin C1 to which it binds exclusively. Studies show that in the airway remodeling of patients with chronic asthma, semaphorin 7A is a potentially important modulator of eosinophil profibrotic functions. In addition, semaphorin-7A plays an important role as an inducer of pulmonary fibrosis and liver fibrogenesis².

The semaphorin family has been classified into eight subclasses. Unlike other semaphorins, which are integral membrane proteins, semaphorin 7A is anchored to the membrane by a glycophosphatidylinositol (GPI)-linked sequence. The conserved amino‐terminal “Sema” domain of the protein includes arginine–glycine–aspartate sequence¹.