Pro-Inflammatory Chemokines and Cytokines Dominate the Blister Fluid Molecular Signature in Patients with Epidermolysis Bullosa and Affect Leukocyte and Stem Cell Migration

Hereditary epidermolysis bullosa (EB) is associated with skin blistering and the development of chronic non-healing wounds. Although clinical studies have shown that cell-based therapies improve wound healing, the recruitment of therapeutic cells to blistering skin and to more advanced skin lesions remains a challenge. Here, we analyzed cytokines and chemokines in blister fluids of patients affected by dystrophic, junctional, and simplex EB. Our analysis revealed high levels of CXCR1, CXCR2, CCR2, and CCR4 ligands, particularly dominant in dystrophic and junctional EB. In vitro migration assays demonstrated the preferential recruitment of CCR4(+) lymphocytes and CXCR1(+), CXCR2(+), and CCR2(+) myeloid cells toward EB-derived blister fluids. Immunophenotyping of skin-infiltrating leukocytes confirmed substantial infiltration of EB-affected skin with resting (CD45RA(+)) and activated (CD45RO(+)) T cells and CXCR2(+) CD11b(+) cells, many of which were identified as CD16b(+) neutrophils. Our studies also showed that abundance of CXCR2 ligand in blister fluids also creates a favorable milieu for the recruitment of the CXCR2(+) stem cells, as validated by in vitro and in-matrix migration assays. Collectively, this study identified several chemotactic pathways that control the recruitment of leukocytes to the EB-associated skin lesions. These chemotactic axes could be explored for the refinement of the cutaneous homing of the therapeutic stem cells.