• Hayden Wilson Stagg, John Greg Whaley, Binu Tharakan, Felicia A Hunter, Daniel Jupiter, Danny C Little, Matthew L Davis, William Roy Smythe, and Ed W Childs.
• From the Department of Surgery (H.W.S., J.G.W., B.T., F.A.H., D.J., D.C.L., M.L.D., W.R.S.), Texas A&M Health Science Center College of Medicine and Scott & White Healthcare, Temple, Texas; and Morehouse School of Medicine (E.W.C.), Atlanta, Georgia.
• J Trauma Acute Care Surg. 2013 Dec 1;75(6):1040-6; discussion 1046.

BackgroundBurns induce systemic microvascular hyperpermeability resulting in shock, and if untreated, cardiovascular collapse. Damage to the endothelial cell adherens junctional complex plays an integral role in the pathophysiology of microvascular hyperpermeability. We hypothesized that doxycycline, a known inhibitor of matrix metalloproteinases (MMPs), could attenuate burn-induced adherens junction damage and microvascular hyperpermeability.MethodsMale Sprague-Dawley rats were divided into sham, burn, and burn + doxycycline (n = 5). The experimental groups underwent a 30% total body surface area full-thickness burn. Fluorescein isothiocyanate-albumin was administered intravenously. Mesenteric postcapillary venules were examined with intravital microscopy to determine flux of albumin from the intravascular space to the interstitium. Fluorescence intensity was compared between the intravascular space to the interstitium at 30, 60, 80, 100, 120, 140, 160, and 180 minutes after burn. Parallel experiments were performed in which rat lung microvascular endothelial cells were treated with sera from sham or burn animals as well as separate groups pretreated with either doxycycline or a specific inhibitor of MMP-9. Monolayer permeability was determined by fluorescein isothiocyanate albumin-flux across Transwell plates and immunofluorescense staining for the adherens junction protein β-catenin was performed. Western blot and gelatin zymography were performed to assess MMP-9 level and activity.ResultsMMP-9 levels were increased after burn. Monolayer permeability was significantly increased with burn serum treatment; this was attenuated with doxycycline as well as the specific MMP-9 inhibitor (p < 0.05). Damage of the endothelial cell adherens junction complex was induced by serum from burned rats, and doxycycline restored the integrity of the adherens junction similar to the MMP-9 inhibitor. Intravital microscopy revealed microvascular hyperpermeability after burn; this was attenuated with doxycycline (p < 0.05).ConclusionBurns induce microvascular hyperpermeability via endothelial adherens junction disruption associated with MMP-9, and this is attenuated with doxycycline.

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