Chemokines are key mediators of leukocyte recruitment in inflammation. However, dysregulated chemokines can cause and/or exacerbate inflammatory diseases, such as atherosclerosis, pulmonary fibrosis and cancer. Due to the complexity of the chemokine system, there is a scarcity of successful treatments1.
Evasins are a family of tick salivary proteins that bind and inhibit chemokines, effectively inhibiting inflammation in vitro and in vivo2. However, wild-type evasins inhibit too many chemokines, potentially leading to off-target effects. Therefore, evasins must be engineered to have the desired specificity for disease-associated chemokines and to minimise off-target immune suppression.
We have developed a pipeline in which we have designed and screened a library of evasin mutants against a target chemokine, CCL7. Analysis of the sequence abundance after screening revealed ~35 evasin sequences were enriched by CCL7 binding. The presence of four variants known to bind to CCL7 validates the screening methodology and suggests that the other similarly enriched sequences represent novel evasin mutants that bind to CCL7.
This work demonstrates the effectiveness of mammalian surface display as a method for screening evasin mutants to identify novel chemokine binders. These findings also represent a step towards developing evasin mutants that bind to disease-specific chemokine subsets.