Ibrahim Nassour

Suppression of the SWI/SNF Component Arid1a Promotes Mammalian Regeneration

Mammals have partially lost the extensive regenerative capabilities of some vertebrates, possibly as a result of chromatin-remodeling mechanisms that enforce terminal differentiation. Here, we show that deleting the SWI/SNF component Arid1a substantially improves mammalian regeneration. Arid1a expression is suppressed in regenerating tissues, and genetic deletion of Arid1a increases tissue repair following an array of injuries. Arid1a deficiency in the liver increases proliferation, reduces tissue damage and fibrosis, and improves organ function following surgical resection and chemical injuries. Hepatocyte-specific deletion is also sufficient to increase proliferation and regeneration without excessive overgrowth, and global Arid1a disruption potentiates soft tissue healing in the ear. We show that Arid1a loss reprograms chromatin to restrict promoter access by transcription factors such as C/ebpα, which enforces differentiation, and E2F4, which suppresses cell-cycle re-entry. Thus, epigenetic reprogramming mediated by deletion of a single gene improves mammalian regeneration and suggests strategies to promote tissue repair after injury.

Carbon Monoxide Protects Against Hemorrhagic Shock and Resuscitation-Induced Microcirculatory Injury and Tissue Injury

ABSTRACT Traumatic injury is a significant cause of morbidity and mortality worldwide. Microcirculatory activation and injury from hemorrhage contribute to organ injury. Many adaptive responses occur within the microcirculatory beds to limit injury including upregulation of heme oxygenase (HO) enzymes, the rate-limiting enzymes in the breakdown of heme to carbon monoxide (CO), iron, and biliverdin. Here we tested the hypothesis that CO abrogates trauma-induced injury and inflammation protecting the microcirculatory beds. Methods: C57Bl/6 mice underwent sham operation or hemorrhagic shock to a mean arterial pressure of 25 mmHg for 120 minutes. Mice were resuscitated with lactated Ringer’s at 2× the volume of maximal shed blood. Mice were randomized to receive CO-releasing molecule or inactive CO-releasing molecule at resuscitation. A cohort of mice was pretreated with tin protoporphyrin-IX to inhibit endogenous CO generation by HOs. Primary mouse liver sinusoidal endothelial cells were cultured for in vitro experiments. Results: Carbon monoxide–releasing molecule protected against hemorrhagic shock/resuscitation organ injury and systemic inflammation and reduced hepatic sinusoidal endothelial injury. Inhibition of HO activity with tin protoporphyrin-IX exacerbated liver hepatic sinusoidal injury. Hemorrhagic shock/resuscitation in vivo or cytokine stimulation in vitro resulted in increased endothelial expression of adhesion molecules that was associated with decreased leukocyte adhesion in vivo and in vitro. Conclusions: Hemorrhagic shock/resuscitation is associated with endothelial injury. Heme oxygenase enzymes and CO are involved in part in diminishing this injury and may prove useful as a therapeutic adjunct that can be harnessed to protect against endothelial activation and damage.

Polymicrobial sepsis is associated with decreased hepatic oxidative phosphorylation and an altered metabolic profile

BACKGROUND Organ failure in sepsis accounts for significant mortality worldwide. Mitochondrial and metabolic responses are central to the overall response of the cell, and thus of the organ and organism. Adaptive responses in metabolism are critical to the recovery at the cellular level. The purpose of these investigations was to test the hypothesis that sepsis is associated with decreased aerobic respiration and significant metabolic changes in the liver. METHODS C57BL/6 mice underwent cecal ligation and puncture (CLP) with a 21 gauge needle or an operation without CLP. Mice were euthanized from 0-24 h after the procedure and liver tissue was harvested. Tissue oxygen consumption and mitochondrial complex activity were measured. Global biochemical profiles of 311 metabolites were performed at the 8-h time point (n = 8/group) and analyzed by gas chromatography-mass spectrometry and liquid chromatography tandem mass spectrometry platforms by Metabolon (Durham, North Carolina). The influence of lipopolysaccharide (LPS) on aerobic and anaerobic respiration in primary mouse hepatocytes was also investigated. RESULTS CLP in vivo or LPS in vitro resulted in a significant decrease in hepatic oxygen consumption. There was a significant decrease in oxidative phosphorylation measured at 12 h. LPS also resulted in a significant increase in anaerobic respiration in hepatocytes. Interestingly, the metabolomic analysis resulted in a metabolic shift in the liver from carbohydrate-based energy to utilization of fatty acids and amino acids. This included an increase in every tricarboxylic acid cycle intermediate and derivative, suggesting an increased flux into the cycle from fatty acid beta-oxidation and anaplerotic contributions from amino acids. CONCLUSIONS Sepsis results in a metabolic response and profile consistent with increased anaerobic respiration, which occurs prior to significant changes in hemodynamics. The metabolic responses of cells and organs may be important adaptive responses to prevent organ failure and death.

Arid1a Has Context-Dependent Oncogenic and Tumor Suppressor Functions in Liver Cancer

ARID1A, an SWI/SNF chromatin-remodeling gene, is commonly mutated in cancer and hypothesized to be tumor suppressive. In some hepatocellular carcinoma patients, ARID1A was highly expressed in primary tumors but not in metastatic lesions, suggesting that ARID1A can be lost after initiation. Mice with liver-specific homozygous or heterozygous Arid1a loss were resistant to tumor initiation while ARID1A overexpression accelerated initiation. In contrast, homozygous or heterozygous Arid1a loss in established tumors accelerated progression and metastasis. Mechanistically, gain of Arid1a function promoted initiation by increasing CYP450-mediated oxidative stress, while loss of Arid1a within tumors decreased chromatin accessibility and reduced transcription of genes associated with migration, invasion, and metastasis. In summary, ARID1A has context-dependent tumor-suppressive and oncogenic roles in cancer.

Minimally Invasive Versus Open Pancreaticoduodenectomy: A Propensity-matched Study From a National Cohort of Patients

Objective: To compare the perioperative outcomes of minimally invasive pancreaticoduodenectomy (MIPD) in comparison with open pancreaticoduodenectomy (OPD) in a national cohort of patients. Background: Limited well-controlled studies exist comparing perioperative outcomes between MIPD and OPD. Methods: Patients who underwent MIPD and OPD were abstracted from the 2014 to 2015 pancreas-targeted American College of Surgeons National Surgical Quality Improvement Program. OPD and MIPD patients were matched 3:1 using propensity score, and perioperative outcomes were compared. Results: A total of 4484 patients were identified with 334 (7.4%) undergoing MIPD. MIPD patients were younger, more likely to be White, and had a lower rate of weight loss. They were more likely to undergo classic Whipple and to have a drain placed. After 3:1 matching, 1002 OPD patients were compared with 334 MIPD patients. MIPD was associated with longer mean operative time (426.6 vs 359.6 minutes; P < 0.01), higher readmission rate (19.2% vs 14.3%; P = 0.04) and lower rate of prolonged length of stay >14 days (16.5% vs 21.6%; P = 0.047). The 2 groups had a similar rate of 30-day mortality (MIPD 1.8% vs OPD 1.3%; P = 0.51), overall complications, postoperative pancreatic fistula, and delayed gastric emptying. A secondary analysis comparing MIPD without conversion or open assist with OPD showed that MIPD patients had lower rates of overall surgical site infection (13.4% vs 19.6%; P = 0.04) and transfusion (7.9% vs 14.4%; P = 0.02). Conclusions: MIPD had an equivalent morbidity and mortality rate to OPD, with the benefit of a decreased rate of prolonged length of stay, though this is partially offset by an increased readmission rate.

Robotic Versus Laparoscopic Pancreaticoduodenectomy: a NSQIP Analysis

BackgroundAn increasing body of literature is supporting the safety of minimally invasive pancreaticoduodenectomy compared to open pancreaticoduodenectomy, but there are limited comparative studies between laparoscopic and robotic pancreaticoduodenectomy.The aim of this study was to compare the rate of postoperative 30-day overall complications between laparoscopic and robotic pancreaticoduodenectomy.MethodsPatients who underwent laparoscopic and robotic pancreaticoduodenectomy were abstracted from the 2014–2015 pancreas-targeted American College of Surgeons National Surgical Quality Improvement Program. A multivariable logistic regression model was developed to determine if the type of minimally invasive approach was associated with 30-day overall complications.ResultsWe identified 428 minimally invasive pancreaticoduodenectomy cases, of which 235 (55%) were performed laparoscopically and 193 (45%) robotically. Patients who underwent the robotic approach were more likely to be white compared to those who underwent the laparoscopic approach and were less likely to have pulmonary disease, undergo preoperative radiotherapy, and have vascular and multivisceral resection. On multivariable analysis, we found that the type of minimally invasive approach, whether laparoscopic or robotic, was not associated with overall complications. The predictors of 30-day overall complications were higher body mass index (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.02–1.09), vascular resection (OR, 2.10; 95% CI, 1.23–3.58), and longer operative time (OR, 1.002; 95% CI, 1.001–1.004).ConclusionsRobotic pancreaticoduodenectomy was associated with a similar 30-day overall complication rate to laparoscopic pancreaticoduodenectomy. Further studies are needed to corroborate these findings and to establish the best approach to perform this complex operation.

Knockdown of Anillin Actin Binding Protein Blocks Cytokinesis in Hepatocytes and Reduces Liver Tumor Development in Mice Without Affecting Regeneration

BACKGROUND & AIMS Cytokinesis can fail during normal postnatal liver development, leading to polyploid hepatocytes. We investigated whether inhibiting cytokinesis in the liver slows tumor growth without compromising the health of normal hepatocytes. We inhibited cytokinesis in cancer cells by knocking down ANLN, a cytoskeletal scaffolding protein that regulates cytokinesis and might promote tumorigenesis, in mice with liver disease. METHODS We analyzed clinical and gene expression data from The Cancer Genome Atlas, Oncomine, PrognoScan, and a hepatocellular carcinoma (HCC) tissue microarray. We knocked down ANLN with small interfering RNAs (siRNAs) in H2.35 liver cells and performed image analyses of cells undergoing cytokinesis. siRNAs were delivered to LAP-MYC mice, which develop hepatoblastoma, using lipid nanoparticles. H2.35 cells with knockdown of ANLN or control cells were injected into FRG mice, which develop chronic liver damage, and tumor growth was monitored. We also developed mice with inducible expression of transgenes encoding small hairpin RNAs (shRNAs) against Anln messenger RNA and studied liver tumorigenesis after administration of diethylnitrosamine and carbon tetrachloride. siRNAs against Anln messenger RNA were conjugated to N-acetylgalactosamine to reduce toxicity and increase hepatocyte tropism; their effects were studied in mouse models of liver cancer and regeneration. RESULTS Levels of ANLN messenger RNA were increased in human HCC tissues compared to non-tumor liver tissues. siRNA knockdown of ANLN blocked cytokinesis in H2.35 liver cells. Administration of siRNA against ANLN increased survival times of LAP-MYC mice, compared to mice given a control siRNA. H2.35 liver cells with shRNA knockdown of ANLN formed tumors more slowly in FRG mice than control H2.35 cells. Mice with inducible expression of shRNAs against Anln mRNA developed fewer liver tumors after administration of diethylnitrosamine and carbon tetrachloride than control mice. Knockdown of ANLN did not affect liver regeneration after acute and chronic liver injuries. CONCLUSIONS Knockdown of ANLN in liver cells blocks cytokinesis and inhibits development of liver tumors in mice. Agents that inhibit ANLN in the liver might be effective for prevention or treatment of HCC.

Prognostic significance of gelsolin and MMP12 in Langerhans cell histiocytosis

Background Gelsolin and matrix metalloproteinase 12 (MMP12) expression has been reported in Langerhans cell histiocytosis (LCH), but the clinical significance of this expression is unknown. We investigated the associations of these proteins with clinical manifestations in patients diagnosed with LCH. Methods We performed a retrospective analysis of clinical data from patients diagnosed with LCH and followed up between 1998 and 2008. Available formalin-fixed, paraffin-embedded specimens were used for gelsolin and MMP12 immunohistochemical staining. We analyzed the expression levels of these proteins and their associations with LCH clinical features. Results Specimens from 36 patients (20 males, 16 females) with a diagnosis of LCH based on CD1a positivity with clinical manifestations were available for immunohistochemical staining. Median patient age was 62 months (range, 5 to 207). The expression of gelsolin varied; it was high in 17 patients (47.2%), low in 11 patients (30.6%), and absent in 8 patients (22.2%). The high gelsolin expression group had a higher tendency for multi-organ and risk organ involvement, although the trend was not statistically significant. MMP12 was detected only in 7 patients (19.4%) who showed multi-system involvement (P=0.018) and lower event-free survival (P=0.002) in comparison to patients with negative MMP12 staining. Conclusion Gelsolin and MMP12 expression may be associated with the clinical course of LCH, and MMP12 expression may be particularly associated with severe LCH. Further studies of larger populations are needed to define the precise role and significance of gelsolin and MMP12 in the pathogenesis of LCH.

Minimally Invasive Liver Surgery for Hepatic Colorectal Metastases.

Minimally invasive surgery has been cautiously introduced in surgical oncology over the last two decades due to a concern of compromised oncological outcomes. Recently, it has been adopted in liver surgery for colorectal metastases. Colorectal cancer is a major cause of cancer-related death in the USA. In addition, liver metastasis is the most common site of distant disease and its resection improves survival. While open resection was the standard of care, laparoscopic liver surgery has become the standard of care for minor liver resections. Laparoscopic liver surgery provides equivalent oncological outcomes with better perioperative results compared to open liver surgery. Robotic liver surgery has been introduced as it is believed to overcome some of the limitations of laparoscopy. Finally, laparoscopic radio-frequency ablation and microwave coagulation can be used as adjuncts in minimally invasive surgery to complement or replace surgical resection when not possible.

Inhaled Carbon Monoxide Protects against the Development of Shock and Mitochondrial Injury following Hemorrhage and Resuscitation

Aims Currently, there is no effective resuscitative adjunct to fluid and blood products to limit tissue injury for traumatic hemorrhagic shock. The objective of this study was to investigate the role of inhaled carbon monoxide (CO) to limit inflammation and tissue injury, and specifically mitochondrial damage, in experimental models of hemorrhage and resuscitation. Results Inhaled CO (250 ppm for 30 minutes) protected against mortality in severe murine hemorrhagic shock and resuscitation (HS/R) (20% vs. 80%; P<0.01). Additionally, CO limited the development of shock as determined by arterial blood pH (7.25±0.06 vs. 7.05±0.05; P<0.05), lactate levels (7.2±5.1 vs 13.3±6.0; P<0.05), and base deficit (13±3.0 vs 24±3.1; P<0.05). A dose response of CO (25–500 ppm) demonstrated protection against HS/R lung and liver injury as determined by MPO activity and serum ALT, respectively. CO limited HS/R-induced increases in serum tumor necrosis factor-α and interleukin-6 levels as determined by ELISA (P<0.05 for doses of 100–500ppm). Furthermore, inhaled CO limited HS/R induced oxidative stress as determined by hepatic oxidized glutathione:reduced glutathione levels and lipid peroxidation. In porcine HS/R, CO did not influence hemodynamics. However, CO limited HS/R-induced skeletal muscle and platelet mitochondrial injury as determined by respiratory control ratio (muscle) and ATP-linked respiration and mitochondrial reserve capacity (platelets). Conclusion These preclinical studies suggest that inhaled CO can be a protective therapy in HS/R; however, further clinical studies are warranted.