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Background: Burns induce a boost in local and systemic complement levels as well as immune cell infiltration in the burn wound, that may negatively affect wound healing. Objective: In this study, the effects of long-term treatment with complement inhibitor C1 esterase inhibitor (C1inh) on post-burn inflammation and wound healing parameters were analyzed in time up to 60 days post-burn. Method: Burned pigs were treated either with or without C1inh up to 15 days post-burn. Burn wound biopsies and blood were collected at different time points up to 60 days post-burn. Thereafter, complement in blood as well as complement and immune cells in the wound, capillary leakage, necrosis, reepithelialization and wound contraction were quantified. Results: No significant differences in complement C3 blood levels were observed at any time point between C1inh-treated and control pigs. In the wound, complement C4 levels were significantly lower in the C1inh group than in controls at day 3-6 and 21-30 post-burn. Similarly, C3 levels, neutrophil and macrophage infiltration in the wound were, although not statistically significant, reduced in C1inh-treated pigs at day 9-14 post-burn. No differences in lymphocyte infiltration in the wound were found between C1inh and control pigs. C1inh-treated pigs also showed reduced capillary leakage. Despite these effects, no significant differences in the long-term wound healing parameters necrosis, reepithelialization and wound contraction were observed between C1inh and control pigs. Conclusion:: In pigs 15 days of C1inh treatment after burn, leads to a reduction in local inflammation and capillary leakage in the burn wound without affecting long-term wound healing parameters.

In a previous study, the authors found persistent presence of acute inflammation markers such as C-reactive protein and complement factors locally in burn wounds. This persistence of acute inflammation may not only delay local burn wound healing but also have a systemic effect, for instance on the heart. Here, the effects of C1 esterase inhibitor (C1inh), an inhibitor of complement activation, on burn wound progression and the heart were analyzed in rats. Dorsal full-thickness burn wounds (2 x 4 cm) were induced on female Wistar rats (n = 14). The rats were divided into two groups (n = 7): a control group (just burns) and a C1inh group. C1inh was administered daily intravenously for 14 days. The burn wound, healthy skin from the hind leg (internal control), and the heart were then fixed in formalin. Tissues were analyzed for granulation tissue formation, reepithelialization, amount and type of infiltrating inflammatory cells (granulocytes and macrophages), and inflammatory markers (complement factors C3 and C4). C1inh treatment significantly reduced the amount of granulation tissue and significantly increased reepithelialization. C1inh also significantly reduced macrophage infiltration. Burns induced infiltration of macrophages into the ventricles of the heart and remarkably also into the atria of the heart. This effect could be counteracted by C1inh. These data show that systemic treatment with C1inh acts at different levels resulting in improved healing locally in burn wounds and systemically reduced inflammation in the heart. Therefore, C1inh might be a possible therapeutic intervention for burn wound patients. (J Burn Care Res 2012;33:544-551)