Characterization of CXCR3 ligand proteoforms in inflammatory lung and joint diseases for identification of therapeutic targets

The chemokines CXCL9, CXCL10 and CXCL11 orchestrate directional trafficking of activated T cells and NK cells through interaction with the G protein-coupled CXC chemokine receptor 3 (CXCR3) and glycosaminoglycans (GAGs). The mRNA for CXCR3 ligands and high protein levels have been reported in cancer, acute and chronic inflammation. Moreover, for all three CXCR3 protein ligands posttranslational modification (PTM) has been reported and some PTMs significantly impact CXCR3 ligand signaling. For instance, processing by CD26 created CXCR3 antagonists in leukocyte migration assays with retained angiostatic activity. The unknown biological effects of other PTMs warrant a detailed functional analysis of CXCR3 ligand proteoforms to understand whether these PTMs affect disease outcome. Moreover, although antibodies allow for sensitive detection of the three CXCR3 ligands, they fail to discriminate between proteoforms with different PTMs and variable activity. Thus, novel methods are needed for sensitive quantitative detection of CXCR3 ligand proteoforms in patient samples. Within this project, we will perform a detailed functional analysis of understudied CXCR3 ligand proteoforms. Moreover, we will combine immunological and biochemical detection methods to quantify individual proteoforms of CXCR3 ligands in patient samples. We will correlate proteoform presence and activity with clinical conditions of patients suffering from inflammatory arthropathies and lung inflammation.