Y. Vigneswaran1, H. Han1, J. Collier1 1University Of Chicago,Surgery,Chicago, IL, USA
Introduction:
Potent antibody and T cell responses elicited by wound healing materials are often assumed to be counterproductive to wound healing, but this is not well studied. Recently, we observed self-assembling peptide nanofiber materials incorporated with specific epitopes can raise strong immune responses without detectable inflammation at sites of delivery. We hypothesized that by engaging this specific non-inflammatory immune response, these materials could be compatible with normal healing and even enhance healing.
Methods:
In mice, an excisional dermal wound healing model was used to study the effects of active immune responses. We used the self-assembling peptide Q11 (QQKFQFQFEQQ) and the OT-II antigen from ovalbumin (T cell and B cell epitope) with either Freund's adjuvant (inflammatory peptide) or without additional adjuvant (non-inflammatory peptide). Mice were naive with no specific antibodys to the material or immunized against the peptides to raise strong antibody responses. Wound healing rates were grossly measured over time in the presence of either the inflammatory or non-inflammatory peptide scaffold (n=20), skin was harvested at various time points for immunohistochemistry (n=18) and lymphocytes isolated for flow cytometry analysis (n=18).
Results:
In the presence of equivalent antibody responses immunized mice had faster healing rates when treated with non-inflammatory peptide compared to inflammatory peptide (p<0.05). The inflammatory peptide treatment had faster healing when mice were not immunized compared to the immunized mice (p<0.05). However the non-inflammatory peptide had no significant difference in healing rates with or without immunization. Immunohistochemistry demonstrated significantly greater recruitment of CD3+ cells to the wound bed by day 17 when immunized (p<0.01). With the non-inflammatory peptide treatment, the ratio of CD4+ to CD8+ cells isolated from the wound beds decreased by day 10 regardless of antibody response (p<0.05). Yet inflammatory peptide treatment showed no significant change in CD4+/CD8+ ratio and at day 10 this ratio was significantly higher than that observed with the non-inflammatory peptide. Additionally cytokine staining of these CD4+ lymphocytes demonstrated higher Th1/Th2 ratio with the inflammatory peptide at all time points compared to the non-inflammatory peptide (p<0.05).
Conclusion:
Here we report that immunogenicity of the material itself is not always detrimental for wound healing. At the cellular level these non-inflammatory peptide nanofibers appear to promote a pro-healing immune phenotype by accelerating the progression of the dominant T cell phenotype from CD4+ to CD8+ cells in the wound and a Th2 slanted response throughout the duration of healing when compared to other immunogenic material. This elicited immune response by peptide nanofibers may provide a unique opportunity to engage the immune response for a more productive wound healing environment.