Development of cytokine-neutralizing gels for local control of inflammation

Inflammation is a highly orchestrated and regulated response to injury that provides a foundation for tissue repair. However, dysregulation of inflammation is detrimental to the host, causing disease, tissue dysfunction, and healing impairment. Modulating inflammation with anti-inflammatory agents could slow disease progression and improve healing outcomes. However, systemic delivery of anti-inflammatory agents can cause immunosuppression, leaving the patients vulnerable to infection and other side effects. Thus, strategies to locally modulate inflammation can be an approach in wound healing and treating conditions characterized by intense inflammatory responses. In this thesis, a novel approach to locally modulate inflammation by conjugating cytokine-neutralizing antibodies to high molecular weight polysaccharides will be presented. The antibodies have been specifically chosen to target pro-inflammatory cytokines TNF-alpha and IL-1beta. The composition of the material was characterized by measuring the concentration of polysaccharide and antibodies independently. The cytokine-neutralizing gels retained binding affinity of antibodies following conjugation or covalent incorporation into crosslinked networks. The non-cross-linked gels were able to modulate inflammatory responses as evidenced by the inhibition of leukocyte infiltration and shifts in macrophage phenotypes. However, the cross-linked gels were not able to promote the same types of responses, which was attributed to slow cytokine diffusion into the gels. The effects of cytokine-neutralizing gels were further evaluated in a rat partial thickness burn model. Hyperinflammation in response to burn induces secondary responses and promotes further complications. We developed a rat partial thickness burn model. Gels that specifically targeted TNF-alpha demonstrated a positive effect on inducing wound closure and reducing necrotic tissue formation, when compared with IL-6-neutralizing gels and controls. IL-1beta concentrations were greatly suppressed in TNF-alpha-neutralizing gels, suggesting that these conjugates were effective in modulating the inflammatory microenvironment at burn sites. Cytokine-neutralizing gels are biologically active both in vitro and in vivo and can be developed into therapeutics to treat a broad range of inflammatory conditions.