Increased survivability of ischemic skin flap tissue in Flk-1+/- mice by Pellino-1 intervention.

OBJECTIVE: Reduced skin flap survival due to ischemia is a serious concern during reconstructive cosmetic surgery. The absence of VEGF and its receptors during ischemia may lead to flap failure. We identified Peli1, a 46-kDa protein, as a proangiogenic molecule and is directly regulated by VEGF. Therefore, we hypothesized that Peli1 acts downstream of Flk-1/VEGFR2 and aids in skin flap survival during ischemia. METHODS: Scratch and matrigel assays were performed to observe cell proliferation, migration, and tube formation in vitro. Western blot analysis was carried out to detect the phosphorylation of Akt (p-Akt) and MAPKAPK2 (p-MK2) in HUVECs. The translational potential of Peli1 pretreatment in the rescue of skin flap tissue was studied in vivo using Flk-1+/- mice. Animals underwent dorsal ischemic skin flap surgery, and the tissue was collected on day 12 for analysis. RESULTS: Western blot analysis revealed a direct relationship between Peli1 and VEGF, as demonstrated by loss-of-function and gain-of-function studies. In addition, pretreatment with Ad.Peli1 restored the phosphorylation of Akt and MK2 and improved the migration potential of Flk-1-knockdown cells. Ad.Peli1 pretreatment salvaged the ischemic skin flap of Flk-1+/- mice by increasing blood perfusion and reducing the inflammatory response and the extent of necrosis. CONCLUSION: Our findings reveal that Peli1 is a proangiogenic molecule that acts downstream of VEGF-Flk-1 and restores angiogenesis and enhances skin flap survivability.

Thioredoxin-1 attenuates sepsis-induced cardiomyopathy after cecal ligation and puncture in mice.

BACKGROUND: Sepsis is a leading cause of mortality among patients in intensive care units across the USA. Thioredoxin-1 (Trx-1) is an essential 12 kDa cytosolic protein that, apart from maintaining the cellular redox state, possesses multifunctional properties. In this study, we explored the possibility of controlling adverse myocardial depression by overexpression of Trx-1 in a mouse model of severe sepsis. METHODS: Adult C57BL/6J and Trx-1Tg/+ mice were divided into wild-type sham (WTS), wild-type cecal ligation and puncture (WTCLP), Trx-1Tg/+sham (Trx-1Tg/+S), and Trx-1Tg/+CLP groups. Cardiac function was evaluated before surgery, 6 and 24 hours after CLP surgery. Immunohistochemical and Western blot analysis were performed after 24 hours in heart tissue sections. RESULTS: Echocardiography analysis showed preserved cardiac function in the Trx-1Tg/+ CLP group compared with the WTCLP group. Similarly, Western blot analysis revealed increased expression of Trx-1, heme oxygenase-1 (HO-1), survivin (an inhibitor of apoptosis [IAP] protein family), and decreased expression of thioredoxin-interacting protein (TXNIP), caspase-3, and 3- nitrotyrosine in the Trx-1Tg/+CLP group compared with the WTCLP group. Immunohistochemical analysis showed reduced 4-hydroxynonenal, apoptosis, and vascular leakage in the cardiac tissue of Trx-1Tg/+CLP mice compared with mice in the WTCLP group. CONCLUSIONS: Our results indicate that overexpression of Trx-1 attenuates cardiac dysfunction during CLP. The mechanism of action may involve reduction of oxidative stress, apoptosis, and vascular permeability through activation of Trx-1/HO-1 and anti-apoptotic protein survivin.

Reactive oxygen species-caspase-3 relationship in mediating blood-brain barrier endothelial cell hyperpermeability following oxygen-glucose deprivation and reoxygenation.

OBJECTIVE: Microvascular hyperpermeability that occurs due to breakdown of the BBB is a major contributor of brain vasogenic edema, following IR injury. In microvascular endothelial cells, increased ROS formation leads to caspase-3 activation following IR injury. The specific mechanisms, by which ROS mediates microvascular hyperpermeability following IR, are not clearly known. We utilized an OGD-R in vitro model of IR injury to study this. METHODS: RBMEC were subjected to OGD-R in presence of a caspase-3 inhibitor Z-DEVD, caspase-3 siRNA or an ROS inhibitor L-AA. Cytochrome c levels were measured by ELISA and caspase-3 activity was measured fluorometrically. TJ integrity and cytoskeletal assembly were studied using ZO-1 immunofluorescence and rhodamine phalloidin staining for f-actin, respectively. RESULTS: OGD-R significantly increased monolayer permeability, ROS formation, cytochrome c levels, and caspase-3 activity (p < 0.05) and induced TJ disruption and actin stress fiber formation. Z-DEVD, L-AA and caspase-3 siRNA significantly attenuated OGD-R-induced hyperpermeability (p < 0.05) while only L-AA decreased cytochrome c levels. Z-DEVD and L-AA protected TJ integrity and actin cytoskeletal assembly. CONCLUSIONS: These results suggest that OGD-R-induced hyperpermeability is ROS and caspase-3 dependent and can be regulated by their inhibitors.

Regulation of tumor necrosis factor-α-induced microvascular endothelial cell hyperpermeability by recombinant B-cell lymphoma-extra large.

BACKGROUND: Tumor necrosis factor-α (TNF-α), a cytotoxic cytokine, induces endothelial cell barrier dysfunction and microvascular hyperpermeability, leading to tissue edema, a hallmark of traumatic injuries. The objective of the present study was to determine whether B-cell lymphoma-extra large (Bcl-xL), an antiapoptotic protein, would regulate and protect against TNF-α-mediated endothelial cell barrier dysfunction and microvascular hyperpermeability. METHODS: Rat lung microvascular endothelial cells were grown as monolayers on Transwell membranes, and fluorescein isothiocyanate-bovine albumin flux (5 mg/mL) across the monolayer was measured fluorometrically to indicate changes in monolayer permeability. The rat lung microvascular endothelial cell adherens junctional integrity and actin cytoskeleton was studied using ß-catenin immunofluorescence and rhodamine phalloidin dye, respectively. Pretreatment of caspase-8 inhibitor (Z-IETD-FMK, 100 µM) for 1 hour and transfection of Bcl-2-homology domain 3-interacting domain death agonist small interfering RNA (10 µM) for 48 hours were performed to study their respective effects on TNF-α-induced (10 ng/mL; 1-hour treatment) monolayer permeability. Recombinant Bcl-xL protein (2.5 µg/ml) was transfected in rat lung microvascular endothelial cells for 1 hour, and its effect on permeability was demonstrated using a permeability assay. Caspase-3 activity was assayed fluorometrically. RESULTS: Z-IETD-FMK pretreatment protected the adherens junctions and decreased TNF-α-induced monolayer hyperpermeability. Bcl-2-homology domain 3-interacting domain death agonist small interfering RNA transfection attenuated the TNF-α-induced increase in monolayer permeability. Recombinant Bcl-xL protein showed protection against TNF-α-induced actin stress fiber formation, an increase in caspase-3 activity, and monolayer hyperpermeability. CONCLUSIONS: Our results have demonstrated the protective effects of recombinant Bcl-xL protein against TNF-α-induced endothelial cell adherens junction damage and microvascular endothelial cell hyperpermeability. These findings support the potential for Bcl-xL-based drug development against microvascular hyperpermeability and tissue edema.

Presence of Liver Steatosis Is Associated With Greater Diabetes Remission After Gastric Bypass Surgery.

OBJECTIVE: Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance (IR) and ß-cell dysfunction. Ectopic fat accumulation in liver and muscle causes IR. Since bariatric and metabolic surgery significantly improves fatty liver disease, we hypothesized that coexistence of liver steatosis (i.e., when hepatic IR contributes in T2DM) would be associated with greater diabetes improvement after surgery. RESEARCH DESIGN AND METHODS: A total of 519 patients with T2DM who underwent Roux-en-Y gastric bypass and simultaneous liver biopsy and had a minimum 5-year follow-up were analyzed to assess the independent association between biopsy-proven liver steatosis and postoperative long-term diabetes remission (glycated hemoglobin <6.5% [48 mmol/mol] off medications). RESULTS: Of the 407 patients with biopsy-proven liver steatosis, long-term diabetes remission was achieved in 211 (52%) patients compared with remission in 44 out of 112 (39%) patients without steatosis (P = 0.027). In multivariable analysis, presence of liver steatosis was an independent predictor of long-term diabetes remission (odds ratio 1.96 [95% CI 1.04-3.72]; P = 0.038). Hepatocyte ballooning, lobular inflammation, or fibrosis at baseline did not predict diabetes remission. CONCLUSIONS: This study, for the first time, suggests that in patients with T2DM who are considering bariatric and metabolic surgery, coexistence of liver steatosis is associated with better long-term glycemic outcomes. Furthermore, our data suggest that there are distinct variants of T2DM in which metabolic responses to surgical weight loss are different. A subgroup of patients whose T2DM is characterized by the presence of hepatic steatosis (presumably associated with worse IR) experience better postoperative metabolic outcomes.

Does Colectomy Improve Type 2 Diabetes?

Gastrectomy and gastric bypass improve type 2 diabetes (T2DM), potentially through alterations in intestinal hormones and the microbiome. The aim of this study was to analyze whether colorectal resections result in improvement of T2DM. A total of 171 patients with T2DM who underwent colectomy for benign diseases were studied with a median postoperative follow-up of 3 years (interquartile range [IQR] 1-5). The median BMI and glycated hemoglobin (HbA1c) at baseline and post-colectomy were 30.3 kg/m2 (IQR 26.6-34.6) versus 30.4 kg/m2 (IQR 26.2-35) (p = 0.1), and 6.7% (IQR 6.2-7.5) versus 6.5% (IQR 6.5-7.1) (p = 0.5), respectively. The proportion of patients taking diabetes medications at baseline versus post-colectomy did not differ significantly. Changes in BMI, HbA1c, and status of diabetes medications were not statistically different between the subtypes of colorectal resection. Our experience suggests that colectomy for benign colorectal diseases is not associated with long-term changes in body weight or glycemic control.

Thioredoxin-1 augments wound healing and promote angiogenesis in a murine ischemic full-thickness wound model.

BACKGROUND: Nonhealing wounds are a continuing health problem in the United States. Overproduction of reactive oxygen species is a major causative factor behind delayed wound healing. Previously we reported that thioredoxin-1 treatment could alleviate oxidative stress under ischemic conditions, such as myocardial infarction and hindlimb ischemia. In this study, we explored the potential for thioredoxin-1 gene therapy to effectively aid wound healing through improved angiogenesis in a murine ischemic wound model. METHODS: Full-thickness, cutaneous, ischemic wounds were created in the dorsum skin flap of 8- to 12-week-old CD1 mice. Nonischemic wounds created lateral to the ischemic skin flap served as internal controls. Mice with both ischemic wounds and nonischemic wounds were treated with Adeno-LacZ (1 × 109 pfu) or Adeno-thioredoxin-1 (1 × 109 pfu), injected intradermally around the wound. Digital imaging was performed on days 0, 3, 6, and 9 to assess the rate of wound closure. Tissue samples collected at predetermined time intervals were processed for immunohistochemical analysis. RESULTS: No significant differences in wound closure were identified among the nonischemic wounds control, nonischemic wounds-LacZ, and nonischemic wounds-thioredoxin-1 groups. Hence, only mice with ischemic wounds were further analyzed. The ischemic wounds-thioredoxin-1 group had significant improvement in wound closure on days 6 and 9 after surgery compared with the ischemic wounds control and ischemic wounds-LacZ groups. Immunohistochemical analysis indicated increased thioredoxin-1, vascular endothelial cell growth factor, and ß-catenin levels in the ischemic wounds-thioredoxin-1 group compared with the ischemic wounds control and ischemic wounds-LacZ groups, as well as increased capillary density and cell proliferation, as represented by Ki-67 staining. CONCLUSION: Taken together, thioredoxin-1 gene therapy promotes vascular endothelial cell growth factor signaling and re-epithelialization and activates wound closure in mice with ischemic wounds.

Melatonin Preserves Blood-Brain Barrier Integrity and Permeability via Matrix Metalloproteinase-9 Inhibition.

Microvascular hyperpermeability that occurs at the level of the blood-brain barrier (BBB) often leads to vasogenic brain edema and elevated intracranial pressure following traumatic brain injury (TBI). At a cellular level, tight junction proteins (TJPs) between neighboring endothelial cells maintain the integrity of the BBB via TJ associated proteins particularly, zonula occludens-1 (ZO-1) that binds to the transmembrane TJPs and actin cytoskeleton intracellularly. The pro-inflammatory cytokine, interleukin-1ß (IL-1ß) as well as the proteolytic enzymes, matrix metalloproteinase-9 (MMP-9) are key mediators of trauma-associated brain edema. Recent studies indicate that melatonin a pineal hormone directly binds to MMP-9 and also might act as its endogenous inhibitor. We hypothesized that melatonin treatment will provide protection against TBI-induced BBB hyperpermeability via MMP-9 inhibition. Rat brain microvascular endothelial cells grown as monolayers were used as an in vitro model of the BBB and a mouse model of TBI using a controlled cortical impactor was used for all in vivo studies. IL-1ß (10 ng/mL; 2 hours)-induced endothelial monolayer hyperpermeability was significantly attenuated by melatonin (10 µg/mL; 1 hour), GM6001 (broad spectrum MMP inhibitor; 10 µM; 1 hour), MMP-9 inhibitor-1 (MMP-9 specific inhibitor; 5 nM; 1 hour) or MMP-9 siRNA transfection (48 hours) in vitro. Melatonin and MMP-9 inhibitor-1 pretreatment attenuated IL-1ß-induced MMP-9 activity, loss of ZO-1 junctional integrity and f-actin stress fiber formation. IL-1ß treatment neither affected ZO-1 protein or mRNA expression or cell viability. Acute melatonin treatment attenuated BBB hyperpermeability in a mouse controlled cortical impact model of TBI in vivo. In conclusion, one of the protective effects of melatonin against BBB hyperpermeability occurs due to enhanced BBB integrity via MMP-9 inhibition. In addition, acute melatonin treatment provides protection against BBB hyperpermeability in a mouse model of TBI indicating its potential as a therapeutic agent for brain edema when established in humans.

Tumor necrosis factor-α-induced microvascular endothelial cell hyperpermeability: role of intrinsic apoptotic signaling.

Tumor necrosis factor-α (TNF-α), a pro-apoptotic cytokine, is involved in vascular hyperpermeability, tissue edema, and inflammation. We hypothesized that TNF-α induces microvascular hyperpermeability through the mitochondria-mediated intrinsic apoptotic signaling pathway. Rat lung microvascular endothelial cells grown on Transwell inserts, chamber slides, or dishes were treated with recombinant TNF-α (10 ng/ml) in the presence or absence of a caspase-3 inhibitor, Z-DEVD-FMK (100 µM). Fluorescein isothiocyanate (FITC)-albumin (5 mg/ml) was used as a marker of monolayer permeability. Mitochondrial reactive oxygen species (ROS) was determined using dihydrorhodamine 123 and mitochondrial transmembrane potential using JC-1. The adherens junction integrity and actin cytoskeletal organization were studied using ß-catenin immunofluorescence and rhodamine phalloidin, respectively. Caspase-3 activity was measured fluorometrically. The pretreatment with Z-DEVD-FMK (100 µM) attenuated TNF-α-induced (10 ng/ml) disruption of the adherens junctions, actin stress fiber formation, increased caspase-3 activity, and monolayer hyperpermeability (p < 0.05). TNF-α (10 ng/ml) treatment resulted in increased mitochondrial ROS formation and decreased mitochondrial transmembrane potential. Intrinsic apoptotic signaling-mediated caspase-3 activation plays an important role in regulating TNF-α-induced endothelial cell hyperpermeability.

Tumor necrosis factor-alpha-induced microvascular endothelial cell hyperpermeability: role of intrinsic apoptotic signaling

Tumor necrosis factor-alfa (TNF-alfa), a pro-apoptotic cytokine, is involved in vascular hyperpermeability, tissue edema, and inflammation. We hypothesized that TNF-alfa induces microvascular hyperpermeability through the mitochondria-mediated intrinsic apoptotic signaling pathway. Rat lung microvascular endothelial cells grown on Transwell inserts, chamber slides, or dishes were treated with recombinant TNF-alfa (10 ng/ml) in the presence or absence of a caspase-3 inhibitor, Z-DEVD-FMK (100 μM). Fluorescein isothiocyanate (FITC)-albumin (5 mg/ml) was used as a marker of monolayer permeability. Mitochondrial reactive oxygen species (ROS) was determined using dihydrorhodamine 123 and mitochondrial transmembrane potential using JC-1. The adherens junction integrity and actin cytoskeletal organization were studied using β-catenin immunofluorescence and rhodamine phalloidin, respectively. Caspase-3 activity was measured fluorometrically. The pretreatment with Z-DEVD-FMK (100 μM) attenuated TNF-alfa-induced (10 ng/ml) disruption of the adherens junctions, actin stress fiber formation, increased caspase-3 activity, and monolayer hyperpermeability (p < 0.05). TNF-alfa (10 ng/ml) treatment resulted in increased mitochondrial ROS formation and decreased mitochondrial transmembrane potential. Intrinsic apoptotic signaling-mediated caspase-3 activation plays an important role in regulating TNF-α-induced endothelial cell hyperpermeability