Nitrosoglutathione Promotes Flap Survival via Suppression of Reperfusion Injury-Induced Superoxide and Inducible Nitric Oxide Synthase Induction

Exogenous S-nitrosoglutathione attenuates inflammatory response and intestinal epithelial barrier injury in endotoxemic rats

BACKGROUND

Gut barrier injury in sepsis is a major contributor to distant organ dysfunction and bad clinical outcomes. Enteric glia-derived S-nitrosoglutathione (GSNO) has been recognized as a novel modulator of gut barrier integrity. In this study, we tested the potential therapeutic effect and mechanism of exogenous GSNO on endotoxin-induced inflammatory response and intestinal barrier injury in a rat model of endotoxemia.

METHODS

Male Sprague-Dawley rats were randomly assigned to four groups as follows: control (saline only), GSNO, lipopolysaccharide (LPS), and LPS + GSNO. Femoral venous injection of LPS (10 mg/kg) or saline was followed by GSNO (1 mg/kg) or saline injection 15 minutes later. Distal ileum tissues and blood were harvested after 3 hours of LPS/saline injection. The intestinal barrier function was measured histologically and by intestinal permeability to fluorescein isothiocyanate dextran. The ultrastructural change of the epithelial tight junction was observed using transmission electron microscope, and the expression level of tight junction protein ZO-1 was analyzed using immunofluorescence and Western blot. Systemic and intestinal inflammation was measured by analyzing the tumor necrosis factor and interleukin 1β levels in plasma and distal ileum tissue, respectively. The levels of nuclear factor κB (NF-κB) and myosin light-chain kinase in the distal ileum were measured by Western blot.

RESULTS

Compared with the endotoxemic rats, the addition of GSNO reduced the intestinal injury observed in histologic sections, decreased permeability to fluorescein isothiocyanate dextran, attenuated damage of the junction between epithelia, and protected against the LPS-induced expression decrease of ZO-1. Furthermore, addition of GSNO reduced plasma and intestinal tumor necrosis factor and interleukin 1β levels as well as inhibited the LPS-induced up-regulation of myosin light-chain kinase expression and NF-κB p65 level in the intestine.

CONCLUSION

The data indicate that GSNO protects against the LPS-induced systemic inflammatory response and attenuated intestinal inflammation and epithelial barrier injury in rats, possibly through the inhibition of the NF-κB pathway.

Hemoglobin vesicles improve wound healing and tissue survival in critically ischemic skin in mice

Local hypoxia, as due to trauma, surgery, or arterial occlusive disease, may severely jeopardize the survival of the affected tissue and its wound-healing capacity. Initially developed to replace blood transfusions, artificial oxygen carriers have emerged as oxygen therapeutics in such conditions. The aim of this study was to target primary wound healing and survival in critically ischemic skin by the systemic application of left-shifted liposomal hemoglobin vesicles (HbVs). This was tested in bilateral, cranially based dorsal skin flaps in mice treated with a HbV solution with an oxygen affinity that was increased to a P(50) (partial oxygen tension at which the hemoglobin becomes 50% saturated with oxygen) of 9 mmHg. Twenty percent of the total blood volume of the HbV solution was injected immediately and 24 h after surgery. On the first postoperative day, oxygen saturation in the critically ischemic middle flap portions was increased from 23% (untreated control) to 39% in the HbV-treated animals (P < 0.05). Six days postoperatively, flap tissue survival was increased from 33% (control) to 57% (P < 0.01) and primary healing of the ischemic wound margins from 6.6 to 12.7 mm (P < 0.05) after HbV injection. In addition, higher capillary counts and endothelial nitric oxide synthase expression (both P < 0.01) were found in the immunostained flap tissue. We conclude that left-shifted HbVs may ameliorate the survival and primary wound healing in critically ischemic skin, possibly mediated by endothelial nitric oxide synthase-induced neovascularization.

Extracorporeal shock wave treatment modulates skin fibroblast recruitment and leukocyte infiltration for enhancing extended skin-flap survival

Extracorporeal shock wave (ESW) treatment has a positive effect of rescuing ischemic skin flaps. This study assessed whether ESW treatment rescues the compromised flap tissue by suppressing the apoptosis of ischemic tissue and recruiting tissue remodeling. We used a random-pattern extended dorsal-skin-flap (10 x 3 cm) rodent model. Thirty-six male Sprague-Dawley rats were divided into three groups. Group I, the control group, received no treatment. Group II received one session of ESW treatment (500 impulses at 0.15 mJ/mm(2)) immediately after surgery. Group III received two sessions of ESW treatment, immediately and the day after the surgery. Results indicated that the necrotic area in the flaps in group II was significantly smaller than that of the flaps in group I (p<0.01). Transferase dUTP-nick end labeling (TUNEL) analysis revealed a significant decrease in the number of apoptotic cells in group II. Hydrogen peroxide (H(2)O(2)) expression in circulation blood was significantly decreased in group II on the day after ESW treatment. Immunohistochemical staining indicated that compared with no treatment, ESW treatment could substantially increase proliferating cell nuclear antigen (PCNA), endothelial nitric oxide synthase, and prolyl 4-hydroxylase (rPH) expression, reduce CD45 expression, and suppress 8-hydroxyguanosine (8-OG) expression in the ischemic zone of the flap tissue. In conclusion, ESW treatment administered at an optimal dosage exerts a positive effect of rescuing ischemic extended skin flaps. The mechanisms of action of ESWs involve modulation of oxygen radicals, attenuation of leukocyte infiltration, decrease in tissue apoptosis, and recruitment of skin fibroblasts, which results in increased flap tissue survival.

Extracorporeal Shock Wave Enhanced Extended Skin Flap Tissue Survival via Increase of Topical Blood Perfusion and Associated with Suppression of Tissue Pro-Inflammation

OBJECTIVE

Distal skin flap ischemic necrosis is a significant challenge in reconstructive surgery. This study assessed whether extracorporeal shock wave (ESW) treatment rescues compromised flap tissue by enhancing tissue perfusion and is associated with suppression of inflammatory response.

METHODS

This study used the dorsal skin random flap model in a rodent. Thirty-six male Sprague Dawley rats were divided into three groups. Group I, a control group, received no treatment. Group II was administrated 500 impulses of ESW treatment at 0.15 mJ/mm(2) as a single treatment immediately postoperatively. Group III received 500 impulses of ESW at 0.15 mJ/mm(2) applied immediately postoperatively and the day following surgery. Flap blood perfusion was detected by laser Doppler. Flap survival/necrosis area and histological staining of flap ischemia zone was performed on day 7 postoperatively. The tumor necrosis factor alpha, vascular endothelial growth factor, and proliferating cell nuclear antigen expression were evaluated with immunohistochemical staining.

RESULTS

Experimental results indicated that the necrotic area of the flaps in Group II was significantly reduced compared with that in the control group (13 +/- 2.6% versus 42 +/- 5.7%, P < 0.01). There was small and insignificant reduction in the necrotic area in Group III compared with the controls. Flap tissue blood perfusion was significantly increased postoperatively in Group II. Histological staining indicated that ESW treatment substantially increased vascular endothelial growth factor and proliferating cell nuclear antigen expressions, reduced leukocyte infiltration, and suppression of tumor necrosis factor alpha expression in flap tissue ischemic zones in Group II compared with that in controls.

CONCLUSION

Optimal dosage of ESW treatment has a positive effect in rescuing ischemic zone of flap by increasing tissue perfusion and is associated with suppressing inflammatory response.

Depletion of glutathione by buthionine sulfoximine decreases random-pattern skin flap viability in rats

BACKGROUND

Glutathione (GSH) is one of the most highly concentrated intracellular antioxidants. Exogenous GSH has been shown to increase random-pattern skin flap survival. However, the effects of endogenous GSH depletion on random-pattern skin flap viability have never been studied.

MATERIALS AND METHODS

To evaluate the effects of systemic glutathione depletion on random-pattern skin flap survival in rats, 28 Wistar albino rats were divided into control, sham, and BSO (buthionine sulfoximide, a selective inhibitor for gamma-glutamylcysteine synthetase) groups. Dorsal, cranial-based random-pattern skin-flaps were elevated and the percentage of flap necrosis was measured in all rats at the postoperative day 7.

RESULTS

BSO-treated rats showed increased skin flap necrosis when compared with untreated animals (P < 0.001). High-dose BSO treatment group had more clinically evident necrosis than low dose group (P < 0.05).

CONCLUSIONS

This study reveals the importance of endogenous GSH for random skin-flap viability.