Cathepsin G (catG) is a neutral serine protease, is mainly expressed in neutrophils, stored in azurophilic granules, and released upon degranulation at the time of the inflammatory response.
The importance of catG in the inflammation process is multifactorial. It contributes to the recruitment and activation of immune cells, such as neutrophils and macrophages, at the site of inflammation. CatG can also activate cytokines and chemokines, which can further promote the inflammatory response. In addition, cathepsin G degrades extracellular matrix proteins (such as laminin, proteoglycans, collagen, fibronectin, and elastin implying a role in local destruction of connective tissue at sites of injury). This last effect can lead to tissue damage and loss of function. CatG also stimulates platelets via the protease-activated receptor-4 for aggregation and secretion.
Boswellic acids (BAs) tightly bind to the active center of catG, occupying the same part of the binding site as the synthetic catG inhibitor JNJ-10311795 (2-[3-{methyl[1-(2-naphthoyl)piperidin-4-yl]amino}carbonyl)-2-naphthyl]-1-(1-naphthyl)-2-oxoethylphosphonic acid). BAs suppressed the proteolytic activity of catG (IC50 of ∼600 nM) in a competitive and reversible manner.
The conclusion of the reviewed article shows that catG is a functional and pharmacologically target of BAs, and the suppression of the catG activity could explain some of the anti-inflammatory properties of frankincense.
References:
https://doi.org/10.4049/jimmunol.0803574