Comparison of robotic-assisted minimally invasive esophagectomy versus minimally invasive esophagectomy: A propensity-matched study from a single high-volume institution

OBJECTIVE

Robotic-assisted minimally invasive esophagectomy accounts for a growing proportion of esophagectomies, potentially due to improved technical capabilities simplifying the challenging aspects of standard minimally invasive esophagectomy. However, there is limited evidence directly comparing both operations. The objective is to evaluate the short-term and long-term outcomes of robotic-assisted minimally invasive esophagectomy in comparison with the minimally invasive esophagectomy approach for patients with esophageal cancer over a 7-year period at a high-volume center. The primary end points of this study were overall survival and disease-free survival. Secondary end points included operation-specific morbidity, lymph node yield, readmission status, and in-hospital, 30-day, and 90-day mortality.

METHODS

Patients who underwent robotic-assisted minimally invasive esophagectomy or standard minimally invasive esophagectomy over a 7-year period were identified from a prospectively maintained database. Inclusion criteria were patients with stage I to III disease, operations performed past the learning curve, and no evidence of scleroderma or cirrhosis. A 1:3 propensity match (robotic-assisted minimally invasive esophagectomy:minimally invasive esophagectomy) for multiple clinical covariates was performed to identify the final study cohort. Perioperative outcomes were compared between the 2 operations.

RESULTS

A total of 734 patients undergoing minimally invasive esophagectomy (n = 630) or robotic-assisted minimally invasive esophagectomy (n = 104) for esophageal cancer were identified. After exclusions and matching, a total cohort of 246 patients undergoing robotic-assisted minimally invasive esophagectomy (n = 65) or minimally invasive esophagectomy (n = 181) were identified. There was no difference in overall survival (P = .69) or disease-free survival (P = .70). There were no significant differences in rates of major morbidity: pneumonia (17% vs 17%, P = .34), chylothorax (8% vs 9%, P = .95), recurrent laryngeal nerve injury (0% vs 1.5%, P = 1), anastomotic leak (5% vs 4%, P = .49), intraoperative complications (9% vs 8%, P = .73), or complete resection rates (99% vs 96%, P = .68). There was no difference in in-hospital (P = .89), 30-day (P = .66) or 90-day mortality (P = .73) between both cohorts. The robotic-assisted minimally invasive esophagectomy cohort yielded a higher median lymph node harvest in comparison with the minimally invasive esophagectomy cohort (32 vs 29, P = .02).

CONCLUSIONS

Robotic-assisted minimally invasive esophagectomy may improve lymphadenectomy in patients undergoing esophagectomy for cancer. Minimally invasive esophagectomy and robotic-assisted minimally invasive esophagectomy are otherwise associated with similar mortality, morbidity, and perioperative outcomes. Further prospective study is required to investigate whether improved lymph node resection may translate to improved oncologic outcomes.

Transoral endoscopic repair of Zenker diverticulum by a thoracic surgical service

OBJECTIVE

Zenker diverticulum (ZD), a pulsion diverticulum of the esophagus, has been traditionally managed with an open surgical approach, but endoscopic transoral stapling has been reported with increasing frequency. The objective of this study was to evaluate the results of endoscopic repair of ZD by a thoracic surgery service.

METHODS

We conducted a retrospective review of patients who underwent transoral stapling repair of ZD at our institution by the thoracic surgery service. We evaluated perioperative outcomes including dysphagia (1, no dysphagia to 5, unable to swallow saliva) and failure of repair requiring surgical intervention.

RESULTS

A total of 151 patients (median age, 78 years; 75 men, 76 women) underwent evaluation for endoscopic repair of ZD. Endoscopic stapled repair of the ZD was completed in 135. Sixteen patients underwent conversion to open repair. The perioperative mortality was 0.6% (1 patient). The median hospital stay was 2 days (range, 0-18 days). Complications occurred in 5 patients who underwent endoscopic repair. The mean preoperative dysphagia score was 2.8 and improved to 1.2 during follow-up (median, 16 months; P < .001). During further follow-up (median, 52 months), 8 patients (5.3%) had failure of the endoscopic repair requiring open surgery (n = 5) or redo transoral stapling (n = 3).

CONCLUSIONS

Endoscopic stapling repair of ZD can be performed safely with good results in experienced centers by thoracic surgeons with significant esophageal experience. Long-term follow-up is required to evaluate the durability of endoscopic repair of ZD.

Robotic assisted minimally invasive thymectomy with simultaneous bilateral thoracoscopy and contralateral phrenic nerve visualization

Background

Thoracoscopic approaches to thymectomy and anterior mediastinal mass resection has become increasingly common due to the potential for decreased blood loss and hospital length of stay. However, contralateral mediastinal and phrenic nerve visualization if often difficult from these unilateral approaches, which may affect the ability to achieve a full phrenic to phrenic dissection Herein, we present our early experience of robotic assisted minimally invasive thymectomy (RAMIT) with simultaneous bilateral thoracoscopy and contralateral phrenic nerve visualization.

Methods

This was a retrospective review of all sequential patients undergoing RAMIT with simultaneous bilateral thoracoscopy from January 2015 to May 2016. This study was approved by our Institutional Review Board (PRO15080367). Individual patient consent was waived.

Results

Twenty-six patients [median age 58 (range, 29-76) years] were included in this study. Sixteen operations were performed for anterior mediastinal mass, 7 for non-thymomatous myasthenia gravis, and 3 for concurrent myasthenia gravis and thymoma. Median blood loss and hospital stay were 25 mL (range, 3-150 mL) and 3 days (range, 2-8 days), respectively. Twenty-one (80.8%) patients experienced an uncomplicated hospital course. The highest graded complication by Clavien Dindo Classification was a grade III due to pleural effusion requiring drainage via pleural catheter. One patient experienced asymptomatic hemidiaphram palsy postoperatively. There were no 90-day postoperative deaths.

Conclusions

RAMIT with simultaneous bilateral thoracoscopy is a feasible approach that may allow for enhanced visualization and more complete thymic resection compared to existing unilateral minimally invasive operations. Comparative studies and long-term follow up are needed to adequately assess the potential benefits of RAMIT.

Mesh cruroplasty in laparoscopic repair of paraesophageal hernias is not associated with better long-term outcomes compared to primary repair

BACKGROUND

Equipoise still exists regarding routine mesh cruroplasty during laparoscopic paraesophageal hernia (PEH). We aimed to determine whether selective mesh cruroplasty is associated with differences in recurrence and patient-reported outcomes.

METHODS

We compared symptom outcomes (n = 688) and radiographic recurrences (n = 101; at least 10% [or 2 cm] of stomach above hiatus) for 795 non-emergent PEH repair with fundoplication (n = 106 with mesh).

RESULTS

Heartburn, regurgitation, epigastric pain, and anti-reflux medication use decreased significantly in both groups while postoperative dysphagia (mesh; p = 0.14), and bloating (non-mesh; p = 0.32), were unchanged. Radiographic recurrence rates were similar (15 mesh [22%] versus 86 non-mesh [17%]; p = 0.32; median 27 [IQR 14, 53] months), but was associated with surgical dissatisfaction (13% vs 4%; p = 0.007).

CONCLUSIONS

Selective mesh cruroplasty was not associated with differences in symptom outcomes or radiographic recurrence rates during laparoscopic PEH repair. Radiographic recurrence was associated with dissatisfaction, emphasizing the need for continued focus on reducing recurrences.

Non-Elective Paraesophageal Hernia Repair Portends Worse Outcomes in Comparable Patients: a Propensity-Adjusted Analysis

INTRODUCTION

Patients undergoing non-elective paraesophageal hernia repair (PEHR) have worse perioperative outcomes. Because they are usually older and sicker, however, these patients may be more prone to adverse events, independent of surgical urgency. Our study aimed to determine whether non-elective PEHR is associated with differential postoperative outcome compared to elective repair, using propensity-score weighting.

METHODS

We abstracted data for patients undergoing PEHR (n = 924; non-elective n = 171 (19 %); 1997-2010). Using boosted regression, we generated a propensity-weighted dataset. Odds of 30-day/in-hospital mortality and major complications after non-elective surgery were determined.

RESULTS

Patients undergoing non-elective repair were significantly older, had more adverse prognostic factors, and significantly more major complications (38 versus 18 %; p < 0.001) and death (8 versus 1 %; p < 0.001). After propensity weighting, median absolute percentage bias across 28 propensity-score variables improved from 19 % (significant imbalance) to 5.6 % (well-balanced). After adjusting propensity-weighted data for age and comorbidity score, odds of major complications were still nearly two times greater (OR 1.67, CI 1.07-2.61) and mortality nearly three times greater (OR 2.74, CI 0.93-8.1) than for elective repair.

CONCLUSIONS

Even after balancing significant differences in baseline characteristics, non-elective PEHR was associated with worse outcomes than elective repair. Symptomatic patients should be referred for elective repair by experienced surgeons.

Minimally invasive versus open thymectomy: a systematic review of surgical techniques, patient demographics, and perioperative outcomes

BACKGROUND

Thymectomy is the mainstay of treatment for thymoma and other anterior mediastinal tumors, and is often utilized in the management of patients with myasthenia gravis (MG). While traditionally approached through a median sternotomy, minimally invasive approaches to thymectomy have increasingly emerged. The present systematic review was conducted to compare perioperative and clinical outcomes following minimally invasive thymectomy (MIT) and open thymectomy (OT).

METHODS

Articles were obtained through a PubMed literature search. Comparative studies reporting clinical outcomes following MIT and OT were eligible for inclusion. We selected studies with full text availability, written in the English language, published after 2005 and with at least 15 patients in each arm. A descriptive analysis was performed.

RESULTS

Twenty studies were included, involving a total of 2,068 patients undergoing either MIT (n=838) or OT (n=1,230). Within individual studies, MIT and OT cohorts were well matched with regards to patient age and gender, but there was considerable variation across studies. Resected thymomas were consistently larger in OT groups, with mean diameter significantly larger in five studies (MIT, 29-52 mm; OT, 31-77 mm). MIT was consistently associated with a lower estimated blood loss (MIT, 20-200 mL; OT, 86-466 mL), chest tube duration (MIT, 1.3-4.1 days; OT, 2.4-5.3 days), and hospital length of stay (MIT, 1-10.6 days; OT, 4-14.6 days). There were no consistent differences in rates of perioperative complications, thymoma recurrence, MG complete stable remission, or 5-year survival.

CONCLUSIONS

In appropriately selected patients, MIT may reduce blood loss, chest tube duration, and hospital length of stay, with comparable clinical outcomes compared to OT via median sternotomy.

The revised American Joint Committee on Cancer staging system (7th edition) improves prognostic stratification after minimally invasive esophagectomy for esophagogastric adenocarcinoma

BACKGROUND

Staging for esophagogastric adenocarcinoma lacked sufficient prognostic accuracy and was revised. We compared survival prognostication between American Joint Committee on Cancer (AJCC) 6th and 7th editions.

METHODS

We abstracted data for 836 patients who underwent minimally invasive esophagectomy for esophagogastric adenocarcinoma (n = 256 neoadjuvant). Monotonicity and strength of survival trends, by stage, were assessed (log-rank test of trend chi-square statistic) and compared using permutation testing. Overall survival (Cox regression) and model fit (Akaike Information Criterion) were determined.

RESULTS

A greater log-rank test of trend statistic indicated stronger survival trends by stage in AJCC 7th (152.872 vs 167.623; permutation test P < .001) edition. Greater Cox likelihood chi-square value (162.957 vs 173.951) and lower Akaike Information Criterion (4,831.011 vs 4,820.016) indicated better model fit. Superior performance was also shown after neoadjuvant therapy.

CONCLUSION

AJCC 7th edition staging for esophagogastric adenocarcinoma provides superior prognostic stratification after minimally invasive esophagectomy, overall and after neoadjuvant therapy compared with AJCC 6th edition.

Undifferentiated carcinoma of the esophagus: a clinicopathological study of 16 cases

Undifferentiated carcinoma of the esophagus is a rare histologic variant of esophageal carcinoma. Using criteria based on studies of undifferentiated carcinomas arising at other sites, we have collected 16 cases of resected esophageal undifferentiated carcinomas. Patients ranged in age from 39 to 84 years (mean, 65.5 years) and were predominantly male (94%). The tumors were characterized by an expansile growth pattern of neoplastic cells organized in solid sheets and without significant glandular, squamous, or neuroendocrine differentiation. The neoplastic cells had a syncytial-like appearance, little intervening stroma, and patchy tumor necrosis. In a subset of cases, the tumor cells adopted a sarcomatoid (n = 2), rhabdoid (n = 1), or minor component (<5%) of glandular morphology (n = 3). In 1 case, reactive osteoclast-like giant cells were found interspersed among the neoplastic cells. Lymphovascular invasion, perineural invasion, and lymph node metastases were identified in 88%, 56%, and 81% of cases, respectively. In 12 (75%) specimens, the background esophageal mucosa was notable for Barrett esophagus. Consistent with the epithelial nature of these neoplasms, cytokeratin positivity was identified in all cases. In addition, SALL4 expression was present in 8 (67%) of 12 cases. Follow-up information was available for 15 (94%) of 16 patients, all of whom were deceased. Survival after surgery ranged from 1 to 50 months (mean, 11.9 months). Before death, 67% patients had documented locoregional recurrence and/or distant organ metastases. In summary, esophageal undifferentiated carcinomas are aggressive neoplasms and associated with a high incidence of recurrence and/or metastases and a dismal prognosis.

A propensity-matched analysis comparing survival after primary minimally invasive esophagectomy followed by adjuvant therapy to neoadjuvant therapy for esophagogastric adenocarcinoma

OBJECTIVES

Prognosis for patients with locally advanced esophagogastric adenocarcinoma (EAC) is poor with surgery alone, and adjuvant therapy after open esophagectomy is frequently not tolerated. After minimally invasive esophagectomy (MIE); however, earlier return to normal function may render patients better able to receive adjuvant therapy. We examined whether primary MIE followed by adjuvant chemotherapy influenced survival compared with propensity-matched patients treated with neoadjuvant therapy.

METHODS

Patients with stage II or higher EAC treated with MIE (N = 375) were identified. Using 30 pretreatment covariates, propensity for assignment to either neoadjuvant followed by MIE (n = 183; 54%) or MIE as primary therapy (n = 156; 46%) was calculated, generating 97 closely matched pairs. Hazard ratios were adjusted for age, sex, body mass index, smoking, comorbidity, and final pathologic stage.

RESULTS

In propensity-matched pairs, adjusted hazard ratio for death did not differ significantly for primary MIE compared with neoadjuvant (hazard ratio, 0.83; 95% confidence interval, 0.60-1.16). Recurrence patterns were similar between groups and 65% of patients with IIb or greater pathologic stage received adjuvant therapy. Clinical staging was inaccurate in 37 out of 105 patients (35%) who underwent primary MIE (n = 18 upstaged and n = 19 downstaged).

CONCLUSIONS

Primary MIE followed by adjuvant chemotherapy guided by pathologic findings did not negatively influence survival and allowed for accurate staging compared with clinical staging. Our data suggest that primary MIE in patients with resectable EAC may be a reasonable approach, improving stage-based prognostication and potentially minimizing overtreatment in patients with early stage disease through accurate stage assignments. A randomized controlled trial testing this hypothesis is needed.

Prognostic stratification in esophagogastric adenocarcinoma in the revised AJCC staging (7th edition)

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Background: AJCC esophageal staging assigns prognostic groups based on tumor, node, and metastasis classifications. In 2010, AJCC 7th ed. separated adenocarcinoma from squamous cell histology and added tumor grade and number of involved regional nodes. Our study aim was to compare survival prognostication for esophagogastric adenocarcinoma between AJCC 7 and AJCC 6thed. stage groupings. Methods: We abstracted pathology and survival for surgically-resected esophagogastric adenocarcinoma patients (n=836; 1997 to 2011); 256 received induction therapy. AJCC stage was assigned; overall survival in months (esophagectomy to death or most recent alive contact) was analyzed. Discriminatory ability and homogeneity, by stage, was assessed with Kaplan-Meier (KM) curves. Monotonicity comparisons were evaluated with linear trend chi-squared tests. Overall survival was compared using Cox regression and Akaike Information Criterion (AIC) was used to assess model fit. Results: Compared to AJCC 6, AJCC 7 restaged 165 patients. (Table) KM log-rank statistic indicated stronger differentiation in AJCC 7 curves compared to AJCC 6 (166.128 vs 185.523 overall). Cox likelihood ratio (162.957 vs. 173.951 overall) and AIC (4,831.011 vs 4,820.016 overall) indicated better model fit to the survival data for AJCC 7 versus AJCC 6, overall and for induction subgroups (data not shown). As stage group increases, stronger linear trends for survival were observed at 24, 36 and 60 months using AJCC7 stage groupings, overall and for induction subgroups, compared to AJCC 6. Conclusions: AJCC 7 stage groupings demonstrate superior homogeneity, discriminatory ability and monotonicity compared to AJCC 6. Incorporating the extent of nodal disease, and tumor grade into the revised AJCC 7 stage classification improves prognostic stratification of surgically resected esophagogastric adenocarcinoma patients, including patients who received induction therapy. [Table: see text]

Randomized trial comparing minimally invasive esophagectomy and open esophagectomy: early perioperative outcomes appear improved with a minimally invasive approach

Esophagectomy is an important curative treatment modality for esophageal cancer, but is a complex operation with associated risks. A minimally invasive approach to esophagectomy may decrease the risks associated with resection. Recently, an important study was published in the Lancet by Biere and colleagues that reported the results of a randomized study, with the primary endpoint of postoperative pulmonary infection, comparing minimally invasive esophagectomy versus open esophagectomy for esophageal cancer. The findings from this trial confirm the data from previous, non-randomized studies and highlight the substantial early postoperative benefits of minimally invasive esophagectomy.

Effect of the revised AJCC staging (7th edition) on prognostic stratification in patients with surgically resected esophageal squamous cell carcinoma

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Background: Historically, the AJCC esophageal staging system separated patients into prognostic groups based on tumor, node, and metastasis (TNM) classifications. In 2010, the 7th edition (AJCC 7) significantly modified esophageal squamous cell cancer (ESCC) staging by separating ESCC from adenocarcinoma, incorporating tumor grade and location for node negative cancers, and stratifying by the number of involved regional nodes for node positive cancers. Our study aim was to determine whether AJCC 7 stage groupings provide improved survival prognostication compared to 6th edition (AJCC 6). Methods: We abstracted pathology and survival for 150 consecutive ESCC patients who underwent esophagectomy (1994-2012); 44 patients received induction therapy. AJCC 6 and AJCC 7 stages were assigned and overall survival analyzed from esophagectomy to death or most recent alive contact and censored at 60 months. Discriminatory ability and homogeneity within subgroups was assessed with Kaplan-Meier curves and monotonicity comparisons were evaluated with linear trend chi-squared tests. Overall survival was compared using Cox regression and Akaike Information Criterion (AIC) used to assess model fit. Results: Compared to AJCC 6, AJCC 7 upstaged 32 patients from IIa to IIb and 1 patient from IIb to IIIa and downstaged 3 patients from stage IIa to Ib. AJCC 7 subclassified 42 AJCC 6 stage III patients (17 IIIa, 10 IIIb and 15 IIIC). Median overall survival was 19 months. Kaplan-Meier log-rank statistic indicated stronger differentiation in AJCC 7 (19.8 vs 29.7). Cox regression likelihood (19.5 vs 26.1), AIC (618.1 vs 611.6), and linear trend chi-squared at 24- (17.5 vs 24.3) and 60-months (13.3 vs 17.3), were all superior for AJCC 7 stage groupings (AJCC 6 vs AJCC 7, respectively). Conclusions: AJCC 7 stage groupings demonstrate superior homogeneity, discriminatory ability and monotonicity compared to AJCC 6. Incorporating the extent of nodal disease, tumor location and tumor grade into the revised AJCC 7 stage classification improves prognostic stratification of surgically resected ESCC patients, including patients who received induction therapy.

Effect of the revised AJCC staging (7th edition) on prognostic stratification in patients with surgically resected esophageal squamous cell carcinoma

15

Background: Historically, the AJCC esophageal staging system separated patients into prognostic groups based on tumor, node, and metastasis (TNM) classifications. In 2010, the 7th edition (AJCC 7) significantly modified esophageal squamous cell cancer (ESCC) staging by separating ESCC from adenocarcinoma, incorporating tumor grade and location for node negative cancers, and stratifying by the number of involved regional nodes for node positive cancers. Our study aim was to determine whether AJCC 7 stage groupings provide improved survival prognostication compared to 6th edition (AJCC 6). Methods: We abstracted pathology and survival for 150 consecutive ESCC patients who underwent esophagectomy (1994-2012); 44 patients received induction therapy. AJCC 6 and AJCC 7 stages were assigned and overall survival analyzed from esophagectomy to death or most recent alive contact and censored at 60 months. Discriminatory ability and homogeneity within subgroups was assessed with Kaplan-Meier curves and monotonicity comparisons were evaluated with linear trend chi-squared tests. Overall survival was compared using Cox regression and Akaike Information Criterion (AIC) used to assess model fit. Results: Compared to AJCC 6, AJCC 7 upstaged 32 patients from IIa to IIb and 1 patient from IIb to IIIa and downstaged 3 patients from stage IIa to Ib. AJCC 7 subclassified 42 AJCC 6 stage III patients (17 IIIa, 10 IIIb and 15 IIIC). Median overall survival was 19 months. Kaplan-Meier log-rank statistic indicated stronger differentiation in AJCC 7 (19.8 vs 29.7). Cox regression likelihood (19.5 vs 26.1), AIC (618.1 vs 611.6), and linear trend chi-squared at 24- (17.5 vs 24.3) and 60-months (13.3 vs 17.3), were all superior for AJCC 7 stage groupings (AJCC 6 vs AJCC 7, respectively). Conclusions: AJCC 7 stage groupings demonstrate superior homogeneity, discriminatory ability and monotonicity compared to AJCC 6. Incorporating the extent of nodal disease, tumor location and tumor grade into the revised AJCC 7 stage classification improves prognostic stratification of surgically resected ESCC patients, including patients who received induction therapy.

A clinical prediction rule for perioperative mortality and major morbidity after laparoscopic giant paraesophageal hernia repair

OBJECTIVE

In the current era, giant paraesophageal hernia repair by experienced minimally invasive surgeons has excellent perioperative outcomes when performed electively. However, nonelective repair is associated with significantly greater morbidity and mortality, even when performed laparoscopically. We hypothesized that clinical prediction tools using pretreatment variables could be developed that would predict patient-specific risk of postoperative morbidity and mortality.

METHODS

We assessed 980 patients who underwent giant paraesophageal hernia repair (1997-2010; 80% elective and 97% laparoscopic). We assessed the association between clinical predictor covariates, including demographics, comorbidity, and urgency of operation, and risk for in-hospital or 30-day mortality and major morbidity. By using forward stepwise logistic regression, clinical prediction models for mortality and major morbidity were developed.

RESULTS

Urgency of operation was a significant predictor of mortality (elective 1.1% [9/778] vs nonelective 8% [16/199]; P < .001) and major morbidity (elective 18% [143/781] vs nonelective 41% [81/199]; P < .001). The most common adverse outcomes were pulmonary complications (n = 199; 20%). A 4-covariate prediction model consisting of age 80 years or more, urgency of operation, and 2 Charlson comorbidity index variables (congestive heart failure and pulmonary disease) provided discriminatory accuracy for postoperative mortality of 88%. A 5-covariate model (sex, age by decade, urgency of operation, congestive heart failure, and pulmonary disease) for major postoperative morbidity was 68% predictive.

CONCLUSIONS

Predictive models using pretreatment patient characteristics can accurately predict mortality and major morbidity after giant paraesophageal hernia repair. After prospective validation, these models could provide patient-specific risk prediction, tailored for individual patient characteristics, and contribute to decision-making regarding surgical intervention.

Outcomes after minimally invasive esophagectomy: review of over 1000 patients

BACKGROUND

Esophagectomy is a complex operation and is associated with significant morbidity and mortality. In an attempt to lower morbidity, we have adopted a minimally invasive approach to esophagectomy.

OBJECTIVES

Our primary objective was to evaluate the outcomes of minimally invasive esophagectomy (MIE) in a large group of patients. Our secondary objective was to compare the modified McKeown minimally invasive approach (videothoracoscopic surgery, laparoscopy, neck anastomosis [MIE-neck]) with our current approach, a modified Ivor Lewis approach (laparoscopy, videothoracoscopic surgery, chest anastomosis [MIE-chest]).

METHODS

We reviewed 1033 consecutive patients undergoing MIE. Elective operation was performed on 1011 patients; 22 patients with nonelective operations were excluded. Patients were stratified by surgical approach and perioperative outcomes analyzed. The primary endpoint studied was 30-day mortality.

RESULTS

The MIE-neck was performed in 481 (48%) and MIE-Ivor Lewis in 530 (52%). Patients undergoing MIE-Ivor Lewis were operated in the current era. The median number of lymph nodes resected was 21. The operative mortality was 1.68%. Median length of stay (8 days) and ICU stay (2 days) were similar between the 2 approaches. Mortality rate was 0.9%, and recurrent nerve injury was less frequent in the Ivor Lewis MIE group (P < 0.001).

CONCLUSIONS

MIE in our center resulted in acceptable lymph node resection, postoperative outcomes, and low mortality using either an MIE-neck or an MIE-chest approach. The MIE Ivor Lewis approach was associated with reduced recurrent laryngeal nerve injury and mortality of 0.9% and is now our preferred approach. Minimally invasive esophagectomy can be performed safely, with good results in an experienced center.

The laparoscopic approach to paraesophageal hernia repair

INTRODUCTION

Laparoscopic paraesophageal hernia repair continues to be one of the most challenging procedures facing the minimally invasive surgeon.

DISCUSSION

A thorough understanding of the tenets of the operation and advanced skills in minimally invasive laparoscopy are needed for long-term freedom from symptomatic and anatomic recurrence. These include complete reduction of the hernia sac from the mediastinum back into the abdomen with careful preservation of the integrity of muscle and peritoneal lining of the crura, aggressive and complete mobilization of the esophagus to the level of the inferior pulmonary vein, vagal preservation, clear identification of the gastroesophageal junction to allow accurate assessment of the intraabdominal esophageal length, and use of Collis gastroplasty when esophageal lengthening is required for a tension-free intraabdominal repair. Liberal mobilization of the phrenosplenic and phrenogastric attachments substantially increases the mobility of the left limb of the crura, allowing for a tension-free primary closure in a large percentage of patients.

CONCLUSION

The following describes our current approach to laparoscopic paraesophageal hernia repair following a decade of refinement in a high-volume center.

Transcriptomic response of murine liver to severe injury and hemorrhagic shock: a dual-platform microarray analysis

Trauma-hemorrhagic shock (HS/T) is a complex process that elicits numerous molecular pathways. We hypothesized that a dual-platform microarray analysis of the liver, an organ that integrates immunology and metabolism, would reveal key pathways engaged following HS/T. C57BL/6 mice were divided into five groups (n = 4/group), anesthetized, and surgically treated to simulate a time course and trauma severity model: 1) nonmanipulated animals, 2) minor trauma, 3) 1.5 h of hemorrhagic shock and severe trauma (HS/T), 4) 1.5 h HS/T followed by 1 h resuscitation (HS/T+1.0R), 5) 1.5 h HS/T followed by 4.5 h resuscitation (HS/T+4.5R). Liver RNA was hybridized to CodeLink and Affymetrix mouse whole genome microarray chips. Common genes with a cross-platform correlation >0.6 (2,353 genes in total) were clustered using k-means clustering, and clusters were analyzed using Ingenuity Pathways Analysis. Genes involved in the stress response and immunoregulation were upregulated early and remained upregulated throughout the course of the experiment. Genes involved in cell death and inflammatory pathways were upregulated in a linear fashion with elapsed time and in severe injury compared with minor trauma. Three of the six clusters contained genes involved in metabolic function; these were downregulated with elapsed time. Transcripts involved in amino acid metabolism as well as signaling pathways associated with glucocorticoid receptors, IL-6, IL-10, and the acute phase response were elevated in a severity-dependent manner. This is the first study to examine the postinjury response using dual-platform microarray analysis, revealing responses that may enable novel therapies or diagnostics.

Genistein aglycone effect on bone loss is not enhanced by supplemental calcium and vitamin D3: a dose ranging experimental study

Genistein aglycone (GEN) has a favorable effect on bone loss. We investigated the effects of GEN alone or in combination with supplemental calcium and vitamin D(3) in an animal model of bone loss to evaluate if there was additional benefit. Ovariectomized (OVX) and SHAM-OVX rats were used. OVX were divided into 12 groups and randomized to receive: GEN at 27, 54, 200, 500 or 1000 mg (human equivalent dose (HED)/day/ip injection alone or with calcium carbonate (Ca) (360 mg/kg/day/gavages) and vitamin D(3) (D(3)) (50 IU/kg/day/gavages) or Ca/D(3) without GEN or untreated for 6 weeks. SHAM-OVX were randomized into 7 groups and treated with: Ca and D(3) alone or in combination with GEN (same doses as OVX), or left untreated. Bone mineral density (BMD), bone-alkaline phosphatase (b-ALP), collagen C-telopeptides (CTX), osteoprotegerin (OPG) and soluble receptor activator of NFκB ligand (sRANKL) were assessed. Femurs were excised and tested for breaking strength and histology. Uterine weight was analyzed to assess GEN's estrogenic effects on the SHAM-OVX. The most effective dose of GEN, independent of Ca/D(3) supplementation, was 54 mg/day. Higher doses yielded no further improvement in bone biomarkers, histology or strength. Only 1000 mg/day HED of genistein produced statistically significant changes in uterine weight of the SHAM-OVX. This study suggests that 54 mg/day of GEN is the threshold dose for efficacy. In addition, supplemental calcium and vitamin D(3), beyond normal dietary intake do not enhance the effects of genistein on improving measures of bone loss. This observation has implications regarding the use of calcium and vitamin D(3) supplementation.

Molecular dynamics of an alpha-helical polypeptide: Temperature dependence and deviation from harmonic behavior

The mean square amplitudes of atomic fluctuations for a polypeptide (decaglycine) alpha-helix evaluated from molecular dynamics simulations at seven temperatures between 5 and 300 K are compared with analytic harmonic results and with experimental values. Above 100 K the harmonic approximation significantly underestimates the amplitudes of the displacements. Analysis of the time dependence of the fluctuations shows that low-frequency modes (<75 cm(-1)) dominate the atomic fluctuations and that there is a contribution with a very long relaxation time (>10 ps). Quantum corrections to the amplitude of the fluctuations are found to be small above 50 K. The mean square amplitudes obtained from the molecular dynamics simulations are compared with the values derived from x-ray temperature (Debye-Waller) factors for metmyoglobin (80, 250, and 300 K) and ferrocytochrome c (300 K).

Normal mode paths for hydrogen exchange in the peptide ferrichrome

Possible paths for exposure to solvent and hydrogen exchange of the amide protons of ferrichrome, a cyclic hexapeptide, are examined. The paths are obtained from calculations of the vibrational normal modes of ferrichrome and correspond to low energy atomic displacements away from the local minimum in the multidimensional conformational space of the molecule. Exposure of exchangeable groups along the normal modes was determined by using the solvent accessible surface area algorithm of Lee and Richards. Three of the exchangeable protons (Gly(1,2,3,)) are largely exposed to solvent in the x-ray structure while the remaining three exchangeable protons of the ornithines are totally shielded from solvent. A very small number of normal mode displacements are found to expose the Orn(2) and Orn(3) amide groups while the Orn(1) amide proton remains shielded from solvent for all the paths studied. The effective paths for exposure of Orn(2) and Orn(3) correspond to the lowest frequency ( approximately 18 cm(-1)) motions. The paths are characterized in terms of the magnitude and energy of atomic displacements, correlated changes in dihedral angles, and the resulting changes in exposure and hydrogen bonding of exchangeable groups.

Efficacy of genistein aglycone on some cardiovascular risk factors and homocysteine levels: A follow-up study

BACKGROUND AND AIM

Recent evidence suggests that genistein aglycone may act beneficially on surrogate cardiovascular risk markers in postmenopausal women. We assessed the effects of genistein aglycone on some cardiovascular risk factors and homocysteine levels after 3-years of continued therapy in a cohort of osteopenic, postmenopausal women.

METHODS AND RESULTS

The parent study was a randomized, double-blind, placebo-controlled trial involving 389 postmenopausal women with low bone mass for 24 months. Subsequently, a subcohort (138 patients) continued therapy for an additional year. Participants received 54mg of genistein aglycone (n=71) or placebo (n=67), daily. Both arms received calcium and vitamin D(3) in therapeutic doses. Moreover, 4 weeks before randomization procedures and during our follow-up study, all patients received dietary instructions in an isocaloric fat-restricted diet. Blood lipid profiles, fasting glucose and insulin, insulin resistance (HOMA-IR), fibrinogen, osteoprotegerin (OPG) and homocysteine at baseline and after 24 and 36 months of treatment were measured. Compared to placebo, genistein significantly decreased fasting glucose and insulin, HOMA-IR, fibrinogen and homocysteine after 24 and 36 months of treatment. By contrast, isoflavone administration did not affect high-density lipoprotein cholesterol and triglycerides though serum OPG was higher in the genistein recipients. There were no differences in adverse events or discomfort between groups. Results on routine biochemical, liver function, and hematologic testing did not change over time in placebo or genistein group.

CONCLUSIONS

After 3-years of treatment, genistein aglycone plus calcium, vitamin D(3) and a healthy diet showed positive effects on some cardiovascular risk factors and homocysteine levels in a cohort of postmenopausal women with low bone mass.

Laparoscopic and thoracoscopic esophagectomy

Over the past decade, our technique of MIE has evolved considerably. In the incipient phase of our experience, we used a totally laparoscopic approach similar to that described in the initial reports from DePaula and colleagues and Swanstrom and Hansen. However, it was soon apparent that there were several critical disadvantages to a purely laparoscopic approach. Laparoscopic transhiatal mobilization of the esophagus offers suboptimal visualization of important periesophageal structures, including the inferior pulmonary vein and the left mainstem bronchus. Moreover, decreased visibility hindered hemostatic division of periesophageal vessels and negatively impacted the completeness of the mediastinal lymph node dissection. These problems are further exacerbated in taller patients. In light of these considerations, we soon transitioned to a laparoscopic-thoracoscopic McKeown approach (thoracoscopic mobilization of the intrathoracic esophagus, laparoscopic gastric tube creation, cervical anastomosis). To this date, the great majority of our minimally invasive esophagectomies (>500 cases) have been performed with this 3-field technique. Indeed, the procedure has been the mainstay of our experience in the past 10 years with reduced perioperative morbidity and mortality compared with many other open series. In our experience, perhaps the most significant technical concern with this operation is the cervical dissection. Recurrent laryngeal nerve injuries, perturbations in pharyngeal transit, and swallowing dysfunction even in the absence of recurrent nerve injury are not infrequent. Moreover, as described in open series using a cervical anastomosis, anastomotic stricture and leak have been shown to occur with increased frequency [35]. In short, there is a significant learning curve with the cervical dissection. Out of these concerns emerged our more recent experience with completely thoracoscopic-laparoscopic Ivor Lewis esophagectomy. However, we did first evolve through a transition phase whereby a mini-thoracotomy (hybrid approach) was performed for creation of the intrathoracic anastomosis. We believe that the experience with totally thoracoscopic-laparoscopic Ivor Lewis esophagectomy will ultimately reproduce the low morbidity and mortality we have previously published with our established MIE technique. The omission of a cervical dissection has reduced our recurrent nerve injury rate to zero. From a theoretical standpoint, one would presume that pharyngeal transit problems and oropharyngeal swallowing dysfunction should be reduced as well with a chest anastomosis. It should be emphasized that there is a steep operator learning curve associated with this approach. Indeed, thoracoscopic port placement is critical, as poorly positioned trocars can result in difficulty maneuvering instruments through the rigid chest wall. Additionally, both blood and lung can obscure visualization of the esophagus, which lies at the dependent aspect of the operative field. Prone positioning has been described as an alternative approach that may facilitate operative exposure and address such technical concerns. Low rates of anastomotic leak (3%), low mortality (1.5%), and equivalent stage-specific survival compared with open series have been shown with this thoracoscopic prone approach [36]. In conclusion, our technique of MIE has evolved such that laparoscopic-thoracoscopic Ivor Lewis esophagectomy has become our preferred approach. Although somewhat early in our experience, we are convinced that this operative technique is feasible with reproducible results. Perioperative morbidity and mortality are comparable with our previously established MIE with cervical anastomosis while essentially eliminating recurrent nerve injury, limiting the length of the gastric conduit required, and allowing a more aggressive gastric resection margin. Recent data from other publications also suggests that lymph node yields may be improved, although insufficient data exist at this time to comment on oncologic results or outcomes with this technique.

Genistein aglycone reverses glucocorticoid-induced osteoporosis and increases bone breaking strength in rats: a comparative study with alendronate

BACKGROUND AND PURPOSE

Glucocorticoid-induced osteoporosis (GIO) is the leading cause of secondary osteoporosis. Clinical evidence suggests a role for genistein aglycone in the treatment of post-menopausal osteopenia although proof of efficacy in comparison with currently available treatments is still lacking. To clarify this issue, we investigated the effects of genistein on bone compared with alendronate in experimental GIO.

EXPERIMENTAL APPROACH

A total of 28 female Sprague-Dawley rats were used. GIO was induced by daily injections of methylprednisolone (MP; 30 mg x kg(-1) s.c.) for 60 days. Sham GIO animals (Sham-MP) were injected daily with the MP vehicle. At the end of the osteoporosis development period, MP rats were randomized to receive: vehicle (n= 7), genistein aglycone (5 mg x kg(-1) s.c.; n= 7) or alendronate (0.03 mg x kg(-1) s.c.; n= 7). Treatment lasted 60 days. Sham-MP animals were treated with vehicle for an additional 60 days. At the beginning and at the end of treatments, animals were examined for bone mineral density and bone mineral content. Bone-alkaline phosphatase and carboxy-terminal collagen cross links were determined; femurs were removed and tested for breaking strength and histology.

KEY RESULTS

Genistein aglycone showed a greater increase in bone mineral density, bone mineral content and in breaking strength than alendronate and significantly increased bone-alkaline phosphatase (bone formation marker), reduced carboxy-terminal collagen cross links (bone resorption marker), compared with alendronate. Both treatments improved bone histology and the histological score.

CONCLUSION AND IMPLICATIONS

The results strongly suggest that the genistein aglycone might be an alternative therapy for the management of secondary osteoporosis.

A medicinal extract of Scutellaria baicalensis and Acacia catechu acts as a dual inhibitor of cyclooxygenase and 5-lipoxygenase to reduce inflammation

A mixed extract containing two naturally occurring flavonoids, baicalin from Scutellaria baicalensis and catechin from Acacia catechu, was tested for cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) inhibition via enzyme, cellular, and in vivo models. The 50% inhibitory concentration for inhibition of both ovine COX-1 and COX-2 peroxidase enzyme activities was 15 microg/mL, while the mixed extract showed a value for potato 5-LOX enzyme activity of 25 microg/mL. Prostaglandin E2 generation was inhibited by the mixed extract in human osteosarcoma cells expressing COX-2, while leukotriene production was inhibited in both human cell lines, immortalized THP-1 monocyte and HT-29 colorectal adenocarcinoma. In an arachidonic acid-induced mouse ear swelling model, the extract decreased edema in a dose-dependent manner. When arachidonic acid was injected directly into the intra-articular space of mouse ankle joints, the mixed extract abated the swelling and restored function in a rotary drum walking model. These results suggest that this natural, flavonoid mixture acts via "dual inhibition" of COX and LOX enzymes to reduce production of pro-inflammatory eicosanoids and attenuate edema in an in vivo model of inflammation.

Hypoxia activates c-Jun N-terminal kinase via Rac1-dependent reactive oxygen species production in hepatocytes

The earliest events after the induction of hemorrhagic shock (HS) are complex and poorly understood. We have recently demonstrated that decreased tissue perfusion and hypoxia during HS lead to an increased phosphorylation of c-Jun N-terminal kinase (JNK) in vivo. The purpose of these investigations was to test the hypothesis that hypoxia activates JNK via Rac1-dependent reactive oxygen species (ROS) signaling. Mice subjected to HS and resuscitated with Ringer's ethyl pyruvate solution (REPS) or N-acetylcysteine (NAC), two scavengers of ROS, demonstrated decreased levels of phosphorylated JNK. Exposure of primary mouse hepatocytes in culture to 1% oxygen led to increased production of ROS and phosphorylation of JNK. The duration of hypoxia correlated with the level of generation of ROS and JNK activation. The phosphorylation of JNK was attenuated in the presence of ROS scavengers or the nicotinamide adenosine dinucleotide phosphate [NDA(P)H] oxidase inhibitor, diphenyleneiodonium (DPI). In addition, hypoxia increased activation of Rac1. Inhibition of Rac1 activation by adenoviral gene transfer of dominant-negative Rac1 (AdRac1) attenuated both ROS formation and JNK activation. Together, these data suggest that ROS generation during hypoxia in the liver directly leads to JNK activation in a Rac1-dependent process.

Systemic inflammation and remote organ injury following trauma require HMGB1

High-mobility group box 1 (HMGB1) is a 30-kDa DNA-binding protein that displays proinflammatory cytokine-like properties. HMGB1-dependent inflammatory processes have been demonstrated in models of sterile injury, including ischemia-reperfusion injury and hemorrhagic shock. Here, we tested the hypothesis that the systemic inflammatory response and associated remote organ injury that occur after peripheral tissue injury are highly dependent on HMGB1. Toll-like receptor 4 (TLR4) wild-type (WT) mice subjected to bilateral femur fracture after treatment with neutralizing antibodies to HMGB1 had lower serum IL-6 and IL-10 levels compared with mice treated with nonimmune control IgG. Similarly, compared with injured mice treated with control IgG, anti-HMGB1 antibody-treated mice had lower serum alanine aminotransferase levels and decreased hepatic and gut mucosal NF-κB DNA binding. TLR4 mutant (C3H/HeJ) mice subjected to bilateral femur fracture had less systemic inflammation and liver injury than WT controls. Residual trauma-induced systemic inflammation and hepatocellular injury were not ameliorated by treatment with a polyclonal anti-HMGB1 antibody, even though HMGB1 levels were transiently elevated just 1 h after injury in both WT and C3H/HeJ mice. Collectively, these data demonstrate a critical role for a TLR4-HMGB1 pathway in the initiation of systemic inflammation and end-organ injury following isolated peripheral tissue injury.

Hemorrhagic shock induces NAD(P)H oxidase activation in neutrophils: role of HMGB1-TLR4 signaling

Hemorrhagic shock/resuscitation (HS/R)-induced generation of reactive oxygen species (ROS) plays an important role in posthemorrhage inflammation and tissue injury. We have recently reported that HS/R-activated neutrophils (PMN), through release of ROS, serve an important signaling function in mediating alveolar macrophage priming and lung inflammation. PMN NAD(P)H oxidase has been thought to be an important source of ROS following HS/R. TLR4 sits at the interface of microbial and sterile inflammation by mediating responses to both bacterial endotoxin and multiple endogenous ligands, including high-mobility group box 1 (HMGB1). Recent studies have implicated HMGB1 as an early mediator of inflammation after HS/R and organ ischemia/reperfusion. In the present study, we tested the hypothesis that HS/R activates NAD(P)H oxidase in PMN through HMGB1/TLR4 signaling. We demonstrated that HS/R induced PMN NAD(P)H oxidase activation, in the form of phosphorylation of p47phox subunit of NAD(P)H oxidase, in wild-type mice; this induction was significantly diminished in TLR4-mutant C3H/HeJ mice. HMGB1 levels in lungs, liver, and serum were increased as early as 2 h after HS/R. Neutralizing Ab to HMGB1 prevented HS/R-induced phosphorylation of p47phox in PMN. In addition, in vitro stimulation of PMN with recombinant HMGB1 caused TLR4-dependent activation of NAD(P)H oxidase as well as increased ROS production through both MyD88-IRAK4-p38 MAPK and MyD88-IRAK4-Akt signaling pathways. Thus, PMN NAD(P)H oxidase activation, induced by HS/R and as mediated by HMGB1/TLR4 signaling, is an important mechanism responsible for PMN-mediated inflammation and organ injury after hemorrhage.

Early growth response 1 mediates the systemic and hepatic inflammatory response initiated by hemorrhagic shock

Hemorrhagic shock (HS) is a major cause of morbidity and mortality in trauma patients. The early growth response 1 (Egr-1) transcription factor is induced by a variety of cellular stresses, including hypoxia, and may function as a master switch to trigger the expression of numerous key inflammatory mediators. We hypothesized that HS would induce hepatic expression of Egr-1 and that Egr-1 upregulates the inflammatory response after HS. The Egr-1 mice and wild-type (WT) controls (n>or=5 for all groups) were subjected to HS alone or HS followed by resuscitation (HS/R). Other mice were subjected to a sham procedure which included general anesthesia and vessel cannulation but no shock (sham). After the HS, HS/R, or sham procedures, mice were euthanized for determination of serum concentrations of interleukin (IL) 6, IL-10, and alanine aminotransferase. Northern blot analysis was performed to evaluate Egr-1 messenger RNA (mRNA) expression. Liver whole cell lysates were evaluated for Egr-1 protein expression by Western blot analysis. Hepatic expression of IL-6, granulocyte colony-stimulating factor, and intracellular adhesion molecule 1 mRNA was determined by semiquantitative reverse transcriptase-polymerase chain reaction. The Egr-1 DNA binding was assessed using the electrophoretic mobility shift assay. Hemorrhagic shock results in a rapid and transient hepatic expression of Egr-1 mRNA in WT mice by 1 h, whereas protein and DNA binding activity was evident by 2.5 h. The Egr-1 mRNA expression diminished after 4 h of resuscitation, whereas Egr-1 protein expression and DNA binding activity persisted through resuscitation. The Egr-1 mice exhibited decreased levels of hepatic inflammatory mediators compared with WT controls with a decrease in hepatic mRNA levels of IL-6 by 42%, granulocyte colony-stimulating factor by 39%, and intracellular adhesion molecule 1 by 43%. Similarly, Egr-1 mice demonstrated a decreased systemic inflammatory response and hepatic injury after HS/R compared with their WT counterparts. Early growth response 1 is rapidly upregulated in the liver during and after resuscitation from HS. Our results showing a blunted inflammatory response in Egr-1 mice provides evidence that Egr-1 functions as a proximal signal transduction mechanism responding to shock by amplifying the systemic inflammatory response.

Anti-HMGB1 neutralizing antibody ameliorates gut barrier dysfunction and improves survival after hemorrhagic shock

Intestinal barrier dysfunction occurs following hemorrhagic shock and resuscitation (HS/R). High-mobility group B1 (HMGB1) has been shown to increase the permeability of Caco-2 human enterocyte-like epithelial monolayers in vitro. In this study, we found that serum concentrations of HMGB1 were higher in blood samples obtained from 25 trauma victims with hemorrhagic shock than in 9 normal volunteers. We also studied whether treatment with anti-HMGB1 antibody can ameliorate HS/R-induced gut barrier dysfunction in mice. Animals were shocked by withdrawal of blood to maintain mean arterial pressure at 25 to 30 mmHg for 2 h. After resuscitation with shed blood plus Ringer's lactate solution, the mice were treated with either anti-HMGB1 antibody or nonimmune rabbit IgG. Serum HMGB1 concentrations were significantly higher in trauma victims than control mice. Treatment with anti-HMGB1 antibody improved survival at 24 h and ameliorated the development of ileal mucosal hyperpermeability to FITC-labeled dextran. At 24 h after HS/R, treatment with anti-HMGB1 antibody decreased bacterial translocation to mesenteric lymph nodes and was associated with lower circulating concentrations of IL-6 and IL-10. These data support the notion that HMGB1 is a mediator of HS/R-induced gut barrier dysfunction and suggest that anti-HMGB1 antibodies warrant further evaluation as a therapeutic to ameliorate the morbidity of HS/R in trauma patients.

Inhibition of c-Met as a therapeutic strategy for esophageal adenocarcinoma

The hepatocyte growth factor (HGF) receptor c-Met is a tyrosine kinase receptor with established oncogenic properties. We have previously shown that c-Met is usually overexpressed in esophageal adenocarcinoma (EA), yet the implications of c-Met inhibition in EA remain unknown. Three c-Met-overexpressing EA cell lines (Seg-1, Bic-1, and Flo-1) were used to examine the effects of a c-Met-specific small molecule inhibitor (PHA665752) on cell viability, apoptosis, motility, invasion, and downstream signaling pathways. PHA665752 demonstrated dose-dependent inhibition of constitutive and/or HGF-induced phosphorylation of c-Met, which correlated with reduced cell viability and inhibition of extracellular regulated kinase 1/2 phosphorylation in all three EA cell lines. In contrast, PHA665752 induced apoptosis and reduced motility and invasion in only one EA cell line, Flo-1. Interestingly, Flo-1 was the only cell line in which phosphatidylinositol 3-kinase (PI3K)/Akt was induced following HGF stimulation. The PI3K inhibitor LY294002 produced effects equivalent to those of PHA665752 in these cells. We conclude that inhibition of c-Met may be a useful therapeutic strategy for EA. Factors other than receptor overexpression, such as c-Met-dependent PI3K/Akt signaling, may be predictive of an individual tumor's response to c-Met inhibition.

EMERGING PARADIGM

The systemic inflammatory response syndrome initiated by infection shares many features in common with the trauma-induced systemic response. The toll-like receptors (TLRs) stand at the interface of innate immune activation in the settings of both infection and sterile injury by responding to a variety of microbial and endogenous ligands alike. Recently, a body of literature has evolved describing a key role for TLRs in acute injury using rodent models of hemorrhagic shock, ischemia and reperfusion, tissue trauma and wound repair, and various toxic exposures. This review will detail the observations implicating a TLR family member, TLR4, as a key component of the initial injury response.

Systemic inflammation and remote organ damage following bilateral femur fracture requires Toll-like receptor 4

Extensive soft tissue injury and bone fracture are significant contributors to the initial systemic inflammatory response in multiply injured patients. Systemic inflammation can lead to organ dysfunction remote from the site of traumatic injury. The mechanisms underlying the recognition of peripheral injury and the subsequent activation of the immune response are unknown. Toll-like receptors (TLRs) recognize microbial products but also may recognize danger signals released from damaged tissues. Here we report that peripheral tissue trauma initiates systemic inflammation and remote organ dysfunction. Moreover, this systemic response to a sterile local injury requires toll-like receptor 4 (TLR4). Compared with wild-type (C3H/HeOuJ) mice, TLR4 mutant (C3H/HeJ) mice demonstrated reduced systemic and hepatic inflammatory responses to bilateral femur fracture. Trauma-induced nuclear factor (NF)-κB activation in the liver required functional TLR4 signaling. CD14−/− mice failed to demonstrate protection from fracture-induced systemic inflammation and hepatocellular injury. Therefore, our results also argue against a contribution of intestine-derived LPS to this process. These findings identify a critical role for TLR4 in the rapid recognition and response pathway to severe traumatic injury. Application of these findings in an evolutionary context suggests that multicellular organisms have evolved to use the same pattern recognition receptor for surviving traumatic and infectious challenges.

The role of RAGE in the pathogenesis of intestinal barrier dysfunction after hemorrhagic shock

The receptor for advanced glycation end products (RAGE) has been implicated in the pathogenesis of numerous conditions associated with excessive inflammation. To determine whether RAGE-dependent signaling is important in the development of intestinal barrier dysfunction after hemorrhagic shock and resuscitation (HS/R), C57Bl/6, rage(-/-), or congenic rage(+/+) mice were subjected to HS/R (mean arterial pressure of 25 mmHg for 3 h) or a sham procedure. Twenty-four hours later, bacterial translocation to mesenteric lymph nodes and ileal mucosal permeability to FITC-labeled dextran were assessed. Additionally, samples of ileum were obtained for immunofluorescence microscopy, and plasma was collected for measuring IL-6 and IL-10 levels. HS/R in C57Bl/6 mice was associated with increased bacterial translocation, ileal mucosal hyperpermeability, and high circulating levels of IL-6. All of these effects were prevented when C57Bl/6 mice were treated with recombinant human soluble RAGE (sRAGE; the extracellular ligand-binding domain of RAGE). HS/R induced bacterial translocation, ileal mucosal hyperpermeability, and high plasma IL-6 levels in rage(+/+) but not rage(-/-) mice. Circulating IL-10 levels were higher in rage(-/-) compared with rage(+/+) mice. These results suggest that activation of RAGE-dependent signaling is a key factor leading to gut mucosal barrier dysfunction after HS/R.

IN SILICO MODELS OF ACUTE INFLAMMATION IN ANIMALS

Trauma and hemorrhagic shock elicit an acute inflammatory response, predisposing patients to sepsis, organ dysfunction, and death. Few approved therapies exist for these acute inflammatory states, mainly due to the complex interplay of interacting inflammatory and physiological elements working at multiple levels. Various animal models have been used to simulate these phenomena, but these models often do not replicate the clinical setting of multiple overlapping insults. Mathematical modeling of complex systems is an approach for understanding the interplay among biological interactions. We constructed a mathematical model using ordinary differential equations that encompass the dynamics of cells and cytokines of the acute inflammatory response, as well as global tissue dysfunction. The model was calibrated in C57Bl/6 mice subjected to (1) various doses of lipopolysaccharide (LPS) alone, (2) surgical trauma, and (3) surgery + hemorrhagic shock. We tested the model's predictive ability in scenarios on which it had not been trained, namely, (1) surgery +/- hemorrhagic shock + LPS given at times after the beginning of surgical instrumentation, and (2) surgery + hemorrhagic shock + bilateral femoral fracture. Software was created that facilitated fitting of the mathematical model to experimental data, as well as for simulation of experiments with various inflammatory challenges and associated variations (gene knockouts, inhibition of specific cytokines, etc.). Using this software, the C57Bl/6-specific model was recalibrated for inflammatory analyte data in CD14-/- mice and was used to elucidate altered features of inflammation in these animals. In other experiments, rats were subjected to surgical trauma +/- LPS or to bacterial infection via fibrin clots impregnated with various inocula of Escherichia coli. Mathematical modeling may provide insights into the complex dynamics of acute inflammation in a manner that can be tested in vivo using many fewer animals than has been possible previously.

In silico and in vivo approach to elucidate the inflammatory complexity of CD14-deficient mice

The inflammatory phenotype of genetically modified mice is complex, and the role of Gram-negative lipopolysaccharide (LPS) in acute inflammation induced by surgical cannulation trauma, alone or in combination with hemorrhage and resuscitation ("hemorrhagic shock"), is both complex and controversial. We sought to determine if a mathematical model of acute inflammation could elucidate both the phenotype of CD14-deficient (CD14(-/-)) mice--following LPS, cannulation, or hemorrhagic shock--and the role of LPS in trauma/hemorrhage-induced inflammation. A mathematical model of inflammation initially calibrated in wild-type (C57Bl/6) mice subjected to LPS, cannulation, and hemorrhagic shock was recalibrated in CD14(-/-) mice subjected to the same insults, yielding an ensemble of models that suggested specific differences at the cellular and molecular levels (for example, 43-fold lower activation of leukocytes by LPS). The CD14(-/-)-specific model ensemble could account for complex changes in inflammatory analytes in these mice following LPS treatment. Model prediction of similar organ damage in CD14(-/-) and wild-type mice subjected to cannulation alone or with hemorrhagic shock was verified in vivo (similar ALT levels). These studies suggest that LPS-CD14 responses do not cause inflammation in surgical trauma/hemorrhagic shock and demonstrate a novel use of combined in silico and in vivo methods to elucidate the complex inflammatory phenotype of genetically modified animals.

Anti-HMGB1 neutralizing antibody ameliorates gut barrier dysfunction and improves survival after hemorrhagic shock

Intestinal barrier dysfunction occurs following hemorrhagic shock and resuscitation (HS/R). High-mobility group B1 (HMGB1) has been shown to increase the permeability of Caco-2 human enterocyte-like epithelial monolayers in vitro. In this study, we found that serum concentrations of HMGB1 were higher in blood samples obtained from 25 trauma victims with hemorrhagic shock than in 9 normal volunteers. We also studied whether treatment with anti-HMGB1 antibody can ameliorate HS/R-induced gut barrier dysfunction in mice. Animals were shocked by withdrawal of blood to maintain mean arterial pressure at 25 to 30 mmHg for 2 h. After resuscitation with shed blood plus Ringer's lactate solution, the mice were treated with either anti-HMGB1 antibody or nonimmune rabbit IgG. Serum HMGB1 concentrations were significantly higher in trauma victims than control mice. Treatment with anti-HMGB1 antibody improved survival at 24 h and ameliorated the development of ileal mucosal hyperpermeability to FITC-labeled dextran. At 24 h after HS/R, treatment with anti-HMGB1 antibody decreased bacterial translocation to mesenteric lymph nodes and was associated with lower circulating concentrations of IL-6 and IL-10. These data support the notion that HMGB1 is a mediator of HS/R-induced gut barrier dysfunction and suggest that anti-HMGB1 antibodies warrant further evaluation as a therapeutic to ameliorate the morbidity of HS/R in trauma patients.

Toll-like receptor-4 signaling mediates hepatic injury and systemic inflammation in hemorrhagic shock

BACKGROUND

Hemorrhagic shock and resuscitation (HS/R) activates inflammatory pathways leading to organ injury after trauma. Toll-like receptors (TLRs), such as TLR4, are required for activation of proinflammatory cellular signaling pathways in response to microbial products, but can also recognize endogenous molecules released from damaged tissues. Using mouse strains deficient in TLR4 protein or signaling, we hypothesized that TLR4 would be important for development of systemic inflammation and hepatic injury after HS/R. We sought to determine the role of lipolysaccharide through use of CD14-/- mice.

STUDY DESIGN

TLR4-mutant (C[3H]/HeJ), TLR4-deficient (TLR4-/-), CD14-/-, TLR2-/- mice and wild-type (WT) controls were subjected to HS/R or sham procedure (Sham). At 6.5 hours, mice were euthanized for determination of serum interleukin (IL)-6, IL-10, and alanine aminotransferase concentrations. Hepatic nuclear factor-kappaB DNA-binding (electrophoretic mobility shift assay) and tumor necrosis factor, IL-10, and inducible nitric oxide synthase mRNA expression (semiquantitative reverse transcriptase-polymerase chain reaction) were determined.

RESULTS

Relative to sham, TLR4-competent (C[3H]/HeOuJ) mice exhibited a significant increase in serum alanine aminotransferase, IL-6, and IL-10 after HS/R (p < 0.05). TLR4-mutant (C[3H]/HeJ) mice were protected from HS/R-induced hepatocellular injury and had lower circulating IL-6 and IL-10 levels than WT (p < 0.05). Similarly, TLR4-/- mice had lower circulating IL-6 and IL-10 levels than WT after HS/R (p < 0.05). Hepatic nuclear factor-kappaB activation and tumor necrosis factor, IL-10, and inducible nitric oxide synthase mRNA expression were lower in TLR4-mutant compared with TLR4-competent mice after HS/R. In contrast, serum ALT concentrations were comparable between CD14-/- and TLR2-/- mice and their WT counterparts after HS/R.

CONCLUSIONS

These results suggest that TLR4, but not TLR2, signaling is required for initiation of the systemic inflammatory response and development of hepatocellular injury after HS/R. Lack of involvement of CD14 argues for a lipolysaccharide-independent role for TLR4 in this process.