Colon Capsule Endoscopy: Indications, Findings, and Complications - Data from a Prospective German Colon Capsule Registry Trial (DEKOR).

BACKGROUND/AIMS: Reliable and especially widely accepted preventive measures are crucial to further reduce the incidence of colorectal cancer (CRC). Colon capsule endoscopy (CCE) might increase the screening numbers among patients unable or unwilling to undergo conventional colonoscopy. This registry trial aimed to document and determine the CCE indications, findings, complications, and adverse events in outpatient practices and clinics throughout Germany. METHODS: Patients undergoing CCE between 2010 and 2015 were enrolled in this prospective multicenter registry trial at six German centers. Patient demographics, outcomes, and complications were evaluated. RESULTS: A total of 161 patients were included. Of the CCE evaluations, 111 (68.9%) were considered successful. Pathological findings in the colon (n=92, 60.1%) and in the remaining gastrointestinal tract (n=38, 24.8%) were recorded. The main finding was the presence of polyps (n=52, 32.3%). Furthermore, five carcinomas (3.1%) were detected and histologically confirmed later. Adequate bowel cleanliness was more likely to be achieved in the outpatient setting (p<0.0001). Interestingly, 85 patients (55.6%) chose to undergo CCE based on personal motivation. CONCLUSION: CCE seems to be a reliable and safe endoscopic tool for screening for CRC and detecting other diseases. Its patient acceptance and feasibility seems to be high, especially in the outpatient setting.

Capnography monitoring of non-anesthesiologist provided sedation during percutaneous endoscopic gastrostomy placement: A prospective, controlled, randomized trial.

BACKGROUND AND AIM: A number of studies were able to show a reduction of hypoxemia episodes during procedural sedation through the use of capnography (CA). The present study investigates the number of episodes of hypoxemia during percutaneous endoscopic gastrostomy (PEG) placement with propofol sedation comparing standard monitoring (SM) versus SM with additional CA surveillance. METHODS: In this single center randomized controlled trial, 150 patients were prospectively randomized 1:1 in either the SM group or the CA group after stratification for ASA class, PEG method (push or pull method), presence of head and neck tumor, and tracheostomy. CA analysis was performed for all patients but was blinded for the endoscopic team in the SM group. RESULTS: In the SM group, 57% episodes of hypoxemia (SpO2  < 90% for > 15 s) and 41% episodes of severe hypoxemia (SpO2  < 85% for > 15 s) were observed in comparison with 28% and 20% in the CA group, respectively. Odds ratios for hypoxemia and severe hypoxemia were 0.29 (confidence interval 0.15-0.57; P = 0.0005) and 0.35 (confidence interval 0.17-0.73; P = 0.008) in favor of the CA group. On average, CA was able to detect imminent mild and severe hypoxemia 83 and 99 s before standard monitoring. Standard monitoring represented an independent risk factor for hypoxemia and severe hypoxemia. CONCLUSIONS: Respiratory complications of sedation during PEG placement are frequent events. CA is able to detect imminent hypoxemia at an early time point. This allows an early intervention and consecutively the avoidance of mild and severe hypoxemia. Therefore, CA monitoring can be recommended particularly during PEG insertion procedures.

Time-saving polyp detection in colon capsule endoscopy: evaluation of a novel software algorithm.

BACKGROUND: Colon capsule endoscopy (CCE) is a reliable method to detect colonic polyps in the well-prepared colon. As CCE evaluation can be time consuming, a new software algorithm might aid in reducing evaluation time. OBJECTIVES: The aim of the study was to evaluate whether it is feasible to reliably detect colon polyps in CCE videos with a new software algorithm the "collage mode" (Rapid 8 Software, Covidien/Medtronic®). METHODS: Twenty-nine CCE videos were randomly presented to three experienced and to three inexperienced investigators. Videos were evaluated by applying the collage mode. Investigation time was documented and the results (≥one polyp vs. no polyp) were compared with the findings of two highly experienced central readers who read the CCE videos in the standard mode beforehand. RESULTS: It took a median time of 9.8, 3.5, and 7.5 vs. 4.3, 4.6 and 12.5 min for experienced vs. inexperienced investigators to review the CCE videos. For detecting ≥one polyp vs. no polyp, sensitivity of 93.3%, 73.3%, and 93.3% was observed for the experienced and sensitivity of 46.7%, 33.3%, and 93.3% for the inexperienced CCE readers. CONCLUSION: Collage mode might allow for a quick review of CCE videos with a high polyp detection rate for experienced CCE readers. Future prospective studies should include CCE collage mode for rapid polyp detection to further prove the feasibility of practical colon polyp detection by CCE and possibly support the role of CCE as a screening tool in CRC prevention.

Prophylactic percutaneous endoscopic gastrostomy in patients with head and neck cancer: Influence on nutritional status, utilisation rate and complications.

BACKGROUND: Patients with head and neck cancer (HNC) are at high risk for malnutrition because of tumour localisation and therapy. Prophylactic percutaneous endoscopic gastrostomy (PEG) tube placement is common practice to prevent malnutrition. OBJECTIVE: To investigate the benefits of prophylactic PEG tube placement for HNC patients in terms of the influence on patients' nutritional status, utilisation rate, complications and to identify the predictors of PEG tube utilisation. METHODS: All consecutive HNC patients who underwent prophylactic PEG tube insertion between 1 January 2011 and 31 December 2012 prior to therapy were enrolled. The PEG tube utilisation rate, complications, the patients' nutritional status and tumour therapy were evaluated with the help of electronic patient charts and telephone interviews. RESULTS: A total of 181 patients (48 female, median 67.5 years) were included. The PEG utilisation rate in the entire cohort was 91.7%. One hundred and forty-nine patients (82.3%) used the PEG tube for total enteral nutrition, 17 patients (9.4%) for supplemental nutrition and 15 patients (8.3%) made no use of the PEG tube. Peristomal wound infections were the most common complications (40.3%) in this study. A high Nutritional Risk Screening (NRS) score prior to tube insertion was found to be independently associated with PEG utilisation. No significant weight changes were observed across the three patient subgroups. CONCLUSIONS: The overall PEG tube utilisation rate was high in this study. However, given the high rate of infections, diligent patient selection is crucial in order to determine which patients benefit most from prophylactic PEG tube insertion.

Performance of Three Common Hepatitis C Virus (HCV) Genotyping Assays for Identification of HCV Genotype 2/1 Chimeras.

Besides seven major hepatitis C virus (HCV) genotypes (GT), a number of intergenotypic recombinant strains have been described. These so-called chimeras combine genetic characteristics of different HCV genotypes. However, correct genotype classification is important, as choice and duration of direct-acting antiviral (DAA) treatment is mainly based on the viral genotype. Therefore, misclassification of chimeras might lead to suboptimal treatment of patients infected with these strains. For example, 2k/1b chimeras are typically described as HCV genotype 2 strains by commercially available hybridization assays, but real-time PCR-based tests recognizing another HCV region might be more suitable for correct chimera detection. In this study, the analytic capacity of the hybridization-assay Versant HCV Genotype 2.0 (LiPA 2.0) and the real-time PCR-based-assays cobas HCV GT and Abbott RealTime HCV Genotype II were tested in a selected cohort of 230 patients infected with HCV genotype 1 (n = 53) and 2 (n = 177) and 48 patients infected with HCV 2/1 chimeric strains. While the Versant HCV Genotype 2.0 (LiPA 2.0) assay failed to identify chimeras in all of the patients (48/48, 100%), cobas HCV GT and Abbott HCV Genotype II assays identified chimeras correctly in 90% (43/48) and 65% (31/48) of the cases, respectively. In conclusion, while the hybridization-based Versant HCV Genotype 2.0 (LiPA 2.0) assay seems to be unsuitable for detection of HCV 2/1 chimeras, use of the real-time PCR-based assays cobas HCV GT and Abbott RealTime HCV Genotype II led to a higher rate of chimera detection.

Patient radiation dose in percutaneous biliary interventions: recommendations for DRLs on the basis of a multicentre study.

OBJECTIVE: Percutaneous biliary interventions (PBIs) can be associated with a high patient radiation dose, which can be reduced when national diagnostic reference levels (DRLs) are kept in mind. The aim of this multicentre study was to investigate patient radiation exposure in different percutaneous biliary interventions, in order to recommend national DRLs. METHODS: A questionnaire asking for the dose area product (DAP) and the fluoroscopy time (FT) in different PBIs with ultrasound- or fluoroscopy-guided bile duct punctures was sent to 200 advanced care hospitals. Recommended national DRLs are set at the 75th percentile of all DAPs. RESULTS: Twenty-three facilities (9 interventional radiology depts. and 14 gastroenterology depts.) returned the questionnaire (12%). Five hundred sixty-five PBIs with 19 different interventions were included in the analysis. DAPs (range 4-21,510 cGy·cm2) and FTs (range 0.07-180.33 min) varied substantially depending on the centre and type of PBI. The DAPs of initial PBIs were significantly (p < 0.0001) higher (median 2162 cGy·cm2) than those of follow-up PBIs (median 464 cGy·cm2). There was no significant difference between initial PBIs with ultrasound-guided bile duct puncture (2162 cGy·cm2) and initial PBIs with fluoroscopy-guided bile duct puncture (2132 cGy·cm2) (p = 0.85). FT varied substantially (0.07-180.33 min). CONCLUSIONS: DAPs and FTs in percutaneous biliary interventions showed substantial variations depending on the centre and the type of PBI. PBI with US-guided bile duct puncture did not reduce DAP, when compared to PBI with fluoroscopy-guided bile duct puncture. National DRLs of 4300 cGy·cm2 for initial PBIs and 1400 cGy·cm2 for follow-up PBIs are recommended. KEY POINTS: • DAPs and FTs in percutaneous biliary interventions showed substantial variations depending on the centre and the type of PBI. • PBI with US-guided bile duct puncture did not reduce DAP when compared to PBI with fluoroscopy-guided bile duct puncture. • DRLs of 4300 cGy·cm2for initial PBIs (establishing a transhepatic tract) and 1400 cGy·cm2for follow-up PBIs (transhepatic tract already established) are recommended.

Diagnostic Yield and Outcomes of Computed Tomography of the Head in Critically Ill Nontrauma Patients.

BACKGROUND: Computed tomography of the head (HCT) is a widely used diagnostic tool, especially for emergency and trauma patients. However, the diagnostic yield and outcomes of HCT for patients on medical intensive care units (MICUs) are largely unknown. METHODS: We retrospectively evaluated all head CTs from patients admitted to a single-center MICU during a 5-year period for CT indications, diagnostic yield, and therapeutic consequences. Uni- and multivariate analyses for the evaluation of risk factors for positive head CT were conducted. RESULTS: Six hundred ninety (18.8%) of all patients during a 5-year period underwent HCT; 78.7% had negative CT results, while 21.3% of all patients had at least 1 new pathological finding. The main indication for acquiring CT scan of the head was an altered mental state (AMS) in 23.5%, followed by a new focal neurology in 20.7% and an inadequate wake up after stopping sedation in 14.9% of all patients. The most common new finding was intracerebral bleeding in 6.4%. In 6.7%, the CT scan itself led to a change of therapy of any kind. Admission after resuscitation or a new focal neurology were independent predictors of a positive CT. Psychic alteration and AMS were both independent predictors of a higher chance of a negative head CT. Positive HCT during MICU is an independent predictor of lower survival. CONCLUSIONS: New onset of focal neurologic deficit seems to be a good predictor for a positive CT, while AMS and psychic alterations seem to be very poor predictors. A positive head CT is an independent predictor of death for MICU patients.

Circulating hypoxia marker carbonic anhydrase IX (CA9) in patients with hepatocellular carcinoma and patients with cirrhosis.

BACKGROUND AND AIMS: Expression of carbonic anhydrase IX (CA9), an enzyme expressed in response to hypoxia, acidosis and oncogenic alterations, is reported to be a prognostic factor in HCC patients. Here we evaluated serum CA9 levels in HCC and cirrhosis patients. METHODS: HCC and cirrhosis patients were prospectively recruited and CA9 levels were determined. CA9 levels were compared to stages of cirrhosis and HCC stages. The association of the CA9 levels and overall survival (OS) was assessed. Furthermore, immunohistochemical CA9 expression in HCC and cirrhosis was evaluated. RESULTS: 215 patients with HCC were included. The median serum CA9 concentration in patients with HCC was 370 pg/ml and significantly higher than in a healthy cohort. Patients with advanced cancer stages (BCLC and ALBI score) had hid significant higher levels of CA9 in the serum. HCC patients with high serum CA9 concentrations (>400 pg/ml) had an increased mortality risk (hazard ratio (HR) 1.690, 95% confidence interval (CI) 1.017-2.809, P = 0.043). Serum CA9 concentration in cirrhotic patients did not differ significantly from HCC patients. Higher CA9 levels in cirrhotic patients correlated with portal hypertension and esophageal varices. Patients with ethanol induced cirrhosis had the highest CA9 levels in both cohorts. Levels of CA9 did not correlate with immunohistochemical expression. CONCLUSIONS: We conclude that a high CA9 level is a possible prognostic indicator for a poor outcome in HCC patients. The high CA9 levels are probably mainly associated with portal hypertension. Ductular reactions might be a possible source of serum CA9.

Multispecies blow fly myiasis combined with hypothermia in a man assumed to be dead.

We describe the case of a man who was found with severe hypothermia and advanced myiasis involving five species of blow flies, which eventually led to a transtibial amputation of the man's right leg. A case of such a heavy and species-rich infestation with fly larvae in an urban environment is extraordinary and has, to our knowledge, never been described so far. Best practice in cases such as this one demands accurate species identification not only to ensure appropriate treatment and pest management but also, from a forensic point of view, to explore the possibility of third-party responsibility. The cooperation between physicians and forensic entomologists is highlighted.

Predictive Value of Computed Tomography Scans and Clinical Findings for the Need of Endoscopic Necrosectomy in Walled-off Necrosis From Pancreatitis.

OBJECTIVES: Choosing the best treatment option at the optimal point of time for patients with walled-off necrosis (WON) is crucial. We aimed to identify imaging parameters and clinical findings predicting the need of necrosectomy in patients with WON. METHODS: All patients with endoscopically diagnosed WON and pseudocyst were retrospectively identified. Post hoc analysis of pre-interventional contrast-enhanced computed tomography was performed for factors predicting the need of necrosectomy. RESULTS: Sixty-five patients were included in this study. Forty patients (61.5%) were diagnosed with pseudocyst and 25 patients (38.5%) with WON. Patients with WON mostly had acute pancreatitis with biliary cause compared with more chronic pancreatitis and toxic cause in pseudocyst group (P = 0.002 and P = 0.004, respectively). Logistic regression revealed diabetes as a risk factor for WON. Computed tomography scans revealed 4.62% (n = 3) patients as false positive and 24.6% (n = 16) as false negative findings for WON. Reduced perfusion and detection of solid findings were independent risk factors for WON. CONCLUSIONS: Computed tomography scans are of low diagnostic yield when needed to predict treatment of patients with pancreatic cysts. Reduced pancreatic perfusion and solid findings seem to be a risk factor for WON, whereas patients with diabetes seem to be at higher risk of developing WON.

Multiple plastic stents versus covered metal stent for treatment of anastomotic biliary strictures after liver transplantation: a prospective, randomized, multicenter trial.

BACKGROUND AND AIMS: Treatment of anastomotic biliary strictures (ABSs) after orthotopic liver transplantation by endoscopic insertion of multiple plastic stents (MPSs) is well established. The use of covered self-expandable metal stents (cSEMSs) for this indication is less investigated. METHODS: In an open-label, multicenter, randomized trial, patients with confirmed ABSs were randomly assigned 1:1 to receive either an MPS or a cSEMS. The primary endpoint was the number of endoscopic interventions until ABS resolution. Secondary endpoints were frequency of adverse events, treatment success rates, and time to treatment success and recurrence of ABS during follow-up of at least 1 year. RESULTS: Fifty-eight patients were included between 2012 and 2015, and 48 patients completed follow-up. Patients receiving MPS (n = 24) underwent a median of 4 (range, 3-12) endoscopic retrograde cholangiography examinations, whereas those in the cSEMS group (n = 24) underwent a median of 2 (range, 2-12) sessions until ABS resolution (P < .001). A median of 8 (range, 2-32) stents was used until ABS resolution within the MPS group and 1 (range, 1-24) in the cSEMS group (P < .0001). cSEMS migration occurred in 8 (33.3%) patients. Treatment duration did not differ significantly. Initial treatment success rates were high with 23 (95.8%) in the MPS group and 24 (100%) for cSEMSs (P = 1). Five (20.8%) patients in both groups showed stricture recurrence after a median follow-up of 500 days (range, 48-1317 days). CONCLUSIONS: cSEMSs for treatment of ABSs needed less endoscopic interventions to achieve similar efficacy as MPS and might become a new treatment standard. However, the optimal duration of cSEMS therapy and cost-efficacy have to be evaluated. (Clinical trial registration number: NCT01393067.).

High levels of the soluble programmed death-ligand (sPD-L1) identify hepatocellular carcinoma patients with a poor prognosis.

AIM: Immunotherapy in cancer is a recent and very promising approach, namely the inhibition of the PD/programmed death-ligand 1 (PD-L1) axis. Here we aimed to investigate the prognostic value of a soluble form of PD-L1 in hepatocellular carcinoma (HCC) patients. METHODS: HCC patients were prospectively recruited and soluble programmed death-ligand 1 (sPD-L1) levels were determined. sPD-L1 levels were compared to stages of cirrhosis and HCC. The association of the sPD-L1 levels and overall survival (OS) was assessed. RESULTS: Two hundred fifteen patients with HCC were prospectively included. The median serum sPD-L1 concentration in patients with HCC was 0.5 ng/ml (range 0.03-6.04). Soluble PD-L1 levels positively correlated with the stage of cirrhosis and with stages of HCC. Furthermore, sPD-L1 correlated positively with a marker of macrophage activation (sCD163) and inflammation (C-reactive protein). The cut-off for high-level sPD-L1 (>0.8 ng/ml) was defined by sPD-L1 levels determined in a healthy control cohort. Patients with high serum sPD-L1 concentrations had an increased mortality risk (hazard ratio 3.340, 95 % confidence interval 1.609-6.934, P<0.001), while very low PD-L1 levels seem to come along with better prognosis. High sPD-L1 levels were associated with mortality independently from cirrhosis stage, alpha-fetoprotein and sCD163 levels in a multivariate Cox regression model. CONCLUSIONS: We conclude that a high sPD-L1 level is a possible prognostic indicator for a poor outcome in HCC patients. The predictive value of sPD-L1 levels for a successful anti-PD1/PD-L1 therapy should be investigated in the future.

ERCP in elderly patients: increased risk of sedation adverse events but low frequency of post-ERCP pancreatitis.

BACKGROUND AND AIMS: The continually increasing life expectancy in man comes along with an increasing number of endoscopic interventions performed in patients with advanced or even very advanced age. Data on the feasibility and safety of ERCP in elderly patients are relatively scarce. METHODS: By a systematic query of the University Hospital Frankfurt clinical database, patients undergoing their first ERCP procedure at our center were retrospectively identified. Patients were grouped according to age at the day of the intervention (>80 years, 61-80 years, 40-60 years, and <40 years). Demographic data, indication, outcome, and risk factors were compared among the indicated groups. RESULTS: A total of 758 patients who underwent ERCP procedures at our center were identified and included in the study. Main indications for ERCP were intraductal gallstones in 345 patients (45%) and tumor obstruction of the bile ducts (distal common bile duct: n = 126 [16.5%], hilar cholangiocarcinoma: n = 89 [11.7%], tumor of papilla of Vater: n = 16 [2.1%]). Gallstones were the most common cause for ERCP in patients aged >80 years (53.8%), and normal findings indicating exclusion of relevant disease were more frequent in patients <80 years (13.4%) compared with older patients (4.3%) (P < .01). Sedation adverse events were significantly more common in individuals aged >80 years compared with younger patients (3.4% vs 0.5%; P < .01). However, post-ERCP pancreatitis was significantly less frequent in the older patients (>80 years) (0.9% vs 5.3%; P < .05). Other adverse events were equally distributed in all age groups. The ERCP success rate (>80%) was not different among age groups. CONCLUSIONS: ERCP is safe and efficient in patients aged 80 years or older. However, conscious sedation must be carefully monitored in older patients because risk of sedation adverse events is increased. The incidence of post-ERCP pancreatitis is lower in older patients compared with younger ones.

Colon capsule endoscopy: current status and future directions.

Colon capsule endoscopy (CCE; PillCam Colon; Given Imaging; Yoqneam, Israel) is a minimally invasive wireless technique for the visualization of the colon. With the recent introduction of the second generation colon capsule the diagnostic accuracy of CCE for polyp detection has significantly improved and preliminary data suggest it may be useful to monitor mucosal inflammation in patients with inflammatory bowel disease. Limitations include the inability to take biopsies and the procedural costs. However, given the potentially higher acceptance within an average risk colorectal cancer (CRC) screening population, its usefulness as a screening tool with regard to CRC prevention should be further evaluated.

The capsule endoscopy "suspected blood indicator" (SBI) for detection of active small bowel bleeding: no active bleeding in case of negative SBI.

OBJECTIVE: Capsule endoscopy (CE) is the gold standard to diagnose small bowel bleeding. The "suspected blood indicator" (SBI) offers an automated detection of active small bowel bleeding but validity of this technique is unknown. The objective was to analyze specificity and sensitivity of the SBI using the second small bowel capsule generation for the detection of active bleeding. METHODS: This is a retrospective analysis of all patients (199) who attended our clinic for CE from June 2008 through March 2013. The second-generation PillCam SB 2 capsule was used for detection of (1) luminal blood content and (2) potentially responsible small bowel lesions. The findings of an independent investigator were correlated to SBI findings and a number of SBI markings were analyzed by a receiver operating characteristic (ROC). RESULTS: In 157/199 cases, no sign of active bleeding or altered blood was detected. One hundred and thirty-seven of these 157 cases provided at least one SBI marking and a mean of 18.4 positive SBI markings per record were found. In 20 cases, neither SBI nor the human investigator detected abnormalities. Thirteen patients showed investigator-detected minor bleeding with mean SBI findings of 36 positive screenshots per record. When major bleeding was diagnosed by the investigator (n = 29), SBI detected a mean of 46.6 SBI-positive markings. SBI turned positive in 179 patients, whereas the investigator detected active bleeding in 42 cases. All patients with active bleeding were detected by SBI (sensitivity 100%, specificity 13%). ROC analysis revealed 51.0 SBI markings being the optimal cutoff for active versus no bleeding (sensitivity 79.1%, specificity 90.4%, misclassification of 15.3%). CONCLUSION: The new SBI software is a reliable tool to exclude active bleeding and/or major lesions but analysis of the CE video by a trained investigator is still important for the detection of lesions responsible for past bleeding.

Intraductal endoscopic radiofrequency ablation for the treatment of hilar non-resectable malignant bile duct obstruction.

AIM: To evaluate the safety and technical success of endoscopic radiofrequency ablation (RFA) for palliative treatment of malignant hilar bile duct obstruction. METHODS: In this study, a recently CE and FDA-approved endoscopic RFA catheter was first tested in an ex vivo pig liver model to study the effect of electrosurgical variables on the extent of the area of induced necrosis. Subsequently, a retrospective analysis was conducted of all patients treated with endoscopic RFA for malignant biliary obstruction at our center between February 2012 and April 2013. All patients received an additional plastic stent implantation into the biliary tree following RFA. RESULTS: In the pig model, ablation time of 60-90 seconds using the bipolar soft coagulation mode at 8-10 watts with an effect of 8 was found to be the most feasible setting. Twelve patients (5 females, 7 males; mean age, 70 years) underwent 19 endoscopic RFA (range, 1-5) sessions. Deployment of RFA was successful in all patients. Systemic chemotherapy was administered in four patients. We observed biliary bleeding 4-6 wk after the intervention in three cases and two of these patients died: in one patient, spontaneous hemobilia occurred, whereas bleeding started during stent extraction in the other. In the third patient, bleeding was stopped by insertion of a non-covered self-expanding metal stent. Another three patients developed cholangitis during follow-up. Seven patients died during follow-up and median survival was 6.4 mo (95%CI: 0.05-12.7) from the time of the first RFA. CONCLUSION: Endoscopic RFA is an easy to perform and technically highly successful procedure. However, hemobilia possibly associated with RFA occurred in three of our patients. Therefore, larger prospective studies are needed to further evaluate the safety and efficacy of this promising new method.

Angiopoietin 2 stimulates TIE2-expressing monocytes to suppress T cell activation and to promote regulatory T cell expansion.

Angiopoietin 2 (ANGPT2) is a proangiogenic cytokine whose expression is often upregulated by endothelial cells in tumors. Expression of its receptor, TIE2, defines a highly proangiogenic subpopulation of myeloid cells in circulation and tumors called TIE2-expressing monocytes/macrophages (TEMs). Genetic depletion of TEMs markedly reduces tumor angiogenesis in various tumor models, emphasizing their essential role in driving tumor progression. Previously, we demonstrated that ANGPT2 augments the expression of various proangiogenic genes, the potent immunosuppressive cytokine, IL-10, and a chemokine for regulatory T cells (Tregs), CCL17 by TEMs in vitro. We now show that TEMs also express higher levels of IL-10 than TIE2(-) macrophages in tumors and that ANGPT2-stimulated release of IL-10 by TEMs suppresses T cell proliferation, increases the ratio of CD4(+) T cells to CD8(+) T cells, and promotes the expansion of CD4(+)CD25(high)FOXP3(+) Tregs. Furthermore, syngeneic murine tumors expressing high levels of ANGPT2 contained not only high numbers of TEMs but also increased numbers of Tregs, whereas genetic depletion of tumor TEMs resulted in a marked reduction in the frequency of Tregs in tumors. Taken together, our data suggest that ANGPT2-stimulated TEMs represent a novel, potent immunosuppressive force in tumors.

Angiopoietin-2 regulates gene expression in TIE2-expressing monocytes and augments their inherent proangiogenic functions.

TIE2-expressing monocytes/macrophages (TEM) are a highly proangiogenic subset of myeloid cells in tumors. Here, we show that circulating human TEMs are already preprogrammed in the circulation to be more angiogenic and express higher levels of such proangiogenic genes as matrix metalloproteinase-9 (MMP-9), VEGFA, COX-2, and WNT5A than TIE2(-) monocytes. Additionally, angiopoietin-2 (ANG-2) markedly enhanced the proangiogenic activity of TEMs and increased their expression of two proangiogenic enzymes: thymidine phosphorylase (TP) and cathepsin B (CTSB). Three "alternatively activated" (or M2-like) macrophage markers were also upregulated by ANG-2 in TEMs: interleukin-10, mannose receptor (MRC1), and CCL17. To investigate the effects of ANG-2 on the phenotype and function of TEMs in tumors, we used a double-transgenic (DT) mouse model in which ANG-2 was specifically overexpressed by endothelial cells. Syngeneic tumors grown in these ANG-2 DT mice were more vascularized and contained greater numbers of TEMs than those in wild-type (WT) mice. In both tumor types, expression of MMP-9 and MRC1 was mainly restricted to tumor TEMs rather than TIE2(-) macrophages. Furthermore, tumor TEMs expressed higher levels of MRC1, TP, and CTSB in ANG-2 DT tumors than WT tumors. Taken together, our data show that although circulating TEMs are innately proangiogenic, exposure to tumor-derived ANG-2 stimulates these cells to exhibit a broader, tumor-promoting phenotype. As such, the ANG-2-TEM axis may represent a new target for antiangiogenic cancer therapies.

Switching of vascular phenotypes within a murine breast cancer model induced by angiopoietin-2.

Sustained growth of solid tumours can rely on both the formation of new and the co-option of existing blood vessels. Current models suggest that binding of angiopoietin-2 (Ang-2) to its endothelial Tie2 receptor prevents receptor phosphorylation, destabilizes blood vessels, and promotes vascular permeability. In contrast, binding of angiopoietin-1 (Ang-1) induces Tie2 receptor activation and supports the formation of mature blood vessels covered by pericytes. Despite the intense research to decipher the role of angiopoietins during physiological neovascularization and tumour angiogenesis, a mechanistic understanding of angiopoietin function on vascular integrity and remodelling is still incomplete. We therefore assessed the vascular morphology of two mouse mammary carcinoma xenotransplants (M6378 and M6363) which differ in their natural angiopoietin expression. M6378 displayed Ang-1 in tumour cells but no Ang-2 in tumour endothelial cells in vivo. In contrast, M6363 tumours expressed Ang-2 in the tumour vasculature, whereas no Ang-1 expression was present in tumour cells. We stably transfected M6378 mouse mammary carcinoma cells with human Ang-1 or Ang-2 and investigated the consequences on the host vasculature, including ultrastructural morphology. Interestingly, M6378/Ang-2 and M6363 tumours displayed a similar vascular morphology, with intratumoural haemorrhage and non-functional and abnormal blood vessels. Pericyte loss was prominent in these tumours and was accompanied by increased endothelial cell apoptosis. Thus, overexpression of Ang-2 converted the vascular phenotype of M6378 tumours into a phenotype similar to M6363 tumours. Our results support the hypothesis that Ang-1/Tie2 signalling is essential for vessel stabilization and endothelial cell/pericyte interaction, and suggest that Ang-2 is able to induce a switch of vascular phenotypes within tumours.