Jonathan Cools-Lartigue

Neutrophil extracellular traps sequester circulating tumor cells and promote metastasis

The majority of patients with cancer undergo at least one surgical procedure as part of their treatment. Severe postsurgical infection is associated with adverse oncologic outcomes; however, the mechanisms underlying this phenomenon are unclear. Emerging evidence suggests that neutrophils, which function as the first line of defense during infections, facilitate cancer progression. Neutrophil extracellular traps (NETs) are extracellular neutrophil-derived DNA webs released in response to inflammatory cues that trap and kill invading pathogens. The role of NETs in cancer progression is entirely unknown. We report that circulating tumor cells become trapped within NETs in vitro under static and dynamic conditions. In a murine model of infection using cecal ligation and puncture, we demonstrated microvascular NET deposition and consequent trapping of circulating lung carcinoma cells within DNA webs. NET trapping was associated with increased formation of hepatic micrometastases at 48 hours and gross metastatic disease burden at 2 weeks following tumor cell injection. These effects were abrogated by NET inhibition with DNAse or a neutrophil elastase inhibitor. These findings implicate NETs in the process of cancer metastasis in the context of systemic infection and identify NETs as potential therapeutic targets.

A systematic review of the effects of resident duty hour restrictions in surgery: impact on resident wellness, training, and patient outcomes.

Background:In 2003, the Accreditation Council for Graduate Medical Education (ACGME) mandated 80-hour resident duty limits. In 2011 the ACGME mandated 16-hour duty maximums for PGY1 (post graduate year) residents. The stated goals were to improve patient safety, resident well-being, and education. A systematic review and meta-analysis were performed to evaluate the impact of resident duty hours (RDH) on clinical and educational outcomes in surgery. Methods:A systematic review (1980–2013) was executed on CINAHL, Cochrane Database, Embase, Medline, and Scopus. Quality of articles was assessed using the GRADE guidelines. Sixteen-hour shifts and night float systems were analyzed separately. Articles that examined mortality data were combined in a random-effects meta-analysis to evaluate the impact of RDH on patient mortality. Results:A total of 135 articles met the inclusion criteria. Among these, 42% (N = 57) were considered moderate-high quality. There was no overall improvement in patient outcomes as a result of RDH; however, some studies suggest increased complication rates in high-acuity patients. There was no improvement in education related to RDH restrictions, and performance on certification examinations has declined in some specialties. Survey studies revealed a perception of worsened education and patient safety. There were improvements in resident wellness after the 80-hour workweek, but there was little improvement or negative effects on wellness after 16-hour duty maximums were implemented. Conclusions:Recent RDH changes are not consistently associated with improvements in resident well-being, and have negative impacts on patient outcomes and performance on certification examinations. Greater flexibility to accommodate resident training needs is required. Further erosion of training time should be considered with great caution.

Neutrophils promote liver metastasis via Mac-1 mediated interactions with circulating tumor cells.

Although circulating neutrophils are associated with distant metastasis and poor outcome in a number of epithelial malignancies, it remains unclear whether neutrophils play an active causal role in the metastatic cascade. Using in vivo models of metastasis, we found that neutrophils promote cancer cell adhesion within liver sinusoids and, thereby, influence metastasis. Neutrophil depletion before cancer cell inoculation resulted in a decreased number of gross metastases in an intrasplenic model of liver metastasis. This effect was reversed when inflamed neutrophils were co-inoculated with cancer cells. In addition, early adhesion within liver sinusoids was inhibited in the absence of neutrophils and partially restored with a short perfusion of isolated activated neutrophils. Intravital microscopy showed that cancer cells adhered directly on top of arrested neutrophils, indicating that neutrophils may act as a bridge to facilitate interactions between cancer cells and the liver parenchyma. The adhesion of lipopolysaccharide-activated neutrophils to cancer cells was mediated by neutrophil Mac-1/ICAM-1. Our findings, therefore, show a novel role for neutrophils in the early adhesive steps of liver metastasis.

Neutrophil extracellular traps in cancer progression.

Neutrophils are being increasingly recognized as an important element in tumor progression. They have been shown to exert important effects at nearly every stage of tumor progression with a number of studies demonstrating that their presence is critical to tumor development. Novel aspects of neutrophil biology have recently been elucidated and its contribution to tumorigenesis is only beginning to be appreciated. Neutrophil extracellular traps (NETs) are neutrophil-derived structures composed of DNA decorated with antimicrobial peptides. They have been shown to trap and kill microorganisms, playing a critical role in host defense. However, their contribution to tumor development and metastasis has recently been demonstrated in a number of studies highlighting NETs as a potentially important therapeutic target. Here, studies implicating NETs as facilitators of tumor progression and metastasis are reviewed. In addition, potential mechanisms by which NETs may exert these effects are explored. Finally, the ability to target NETs therapeutically in human neoplastic disease is highlighted.

Cytotoxic effects of violacein in human uveal melanoma cell lines.

Violacein is the main pigment produced by Chromobacterium violaceum, a saprophytic gram-negative bacillus. Violacein is formed by the condensation of two modified tryptophan molecules and has potential anti-neoplastic effects. The purpose of this pilot study was to investigate the in vitro activity of violacein in human uveal melanoma cell lines. Human uveal melanoma cell lines 92.1 and OCM-1 were incubated with five different concentrations of violacein (10−5–10−9 M), and the total cellular protein content was measured by means of the sulphorhodamine B assay. Dose–response curves were obtained and the concentration inhibiting cell growth by 50% (IC50) together with the concentration inhibiting the net cell growth by 50% (GI50) were calculated for both cell lines. Violacein IC50 and GI50 concentrations to cell line 92.1 were 2.78×10−6 M and 1.69×10−6 M, respectively. The IC50 and GI50 concentrations to cell line OCM-1 were 3.69×10−6 M and 2.12×10−6 M, respectively. Previous studies using the same methodology have revealed violacein to have a GI50 in the range (3–6)×10−8 M for MOLT-4 leukaemia, NCI-H460 large cell lung cancer and KM12 colon cancer cell lines. Violacein displayed borderline cytotoxic activity in human uveal melanoma cell lines 92.1 and OCM-1, as measured by the sulphorhodamine B assay, and further studies are necessary to define its suitability as a potential therapeutic agent for metastatic uveal melanoma.

Current Status of Management of Malignant Disease: Current Management of Esophageal Cancer

ObjectiveThe objective of this study is to outline the evidence regarding the surgical management of esophageal cancer and provide a single institutional outline regarding its implementation.BackgroundEsophageal cancer is a major cause of cancer-related morbidity and mortality worldwide. Surgery continues to play an important role in its management and offers the best chance for cure in localized and locally advanced disease. However, considerable controversy exists regarding the optimum treatment strategy in this patient population. Furthermore, despite advances in operative and perioperative care and the advent of minimally invasive approaches, the majority of patients succumb to distant metastases after curative intent resection. This failure highlights the importance of multimodal, stage-directed therapy in the management of patients with newly diagnosed esophageal tumors.MethodsHerein, we provide a comprehensive, evidence-based review of the diagnostic workup and locoregional and systemic treatment options available to esophageal cancer patients. The evidence supporting perioperative chemotherapy versus chemoradiotherapy is outlined and discussed. In addition, we highlight our institutional approach to the diagnostic evaluation, operative selection strategy, and perioperative treatment regimen selection based on the stage of presentation. Finally, we discuss the role of enhanced recovery in the postoperative management of this complex group of patients.ConclusionsEsophageal cancer remains a devastating disease with high mortality. Favorable outcomes mandate a multimodal, stage-directed treatment approach.

Evolution of Percutaneous Dilatational Tracheostomy—A Review of Current Techniques and Their Pitfalls

Tracheostomy is the most commonly performed surgical procedure in critically ill patients with acute respiratory failure. While few absolute indications exist, this procedure is widely used in patients with upper respiratory obstruction and those requiring long-term mechanical ventilation. The traditional approach to tracheostomy has been an open procedure performed in the operating room. This method is associated with an increased rate of complications and costs. Accordingly, percutaneous bedside tracheostomy procedures have largely replaced the traditional operative approach at many institutions. Numerous methods for percutaneous tracheostomy have thus emerged. However, the benefits of one technique versus another have not been well demonstrated. In this article, we review the evidence supporting the use of percutaneous tracheostomy procedures over the traditional operative approach. Furthermore, we review the currently available and emerging methods by which percutaneous tracheostomy can be performed. In addition, we highlight the available evidence concerning the safety and complication rates of each technique.

The impact of incidental gastrointestinal stromal tumours on patients undergoing resection of upper gastrointestinal neoplasms

BACKGROUND Emerging data suggest asymptomatic gastrointestinal stromal tumours (GISTs) of the upper gastrointestinal (UGI) tract are not uncommon. We sought to determine their incidence in patients undergoing resection for UGI neoplasms and their impact on surgical and adjuvant treatment. METHODS We accessed a database prospectively listing all patients undergoing resection of non-GIST neoplasms of the stomach and esophagus at a single university centre over a 4.5-year period and reviewed pathology reports for the presence of synchronous GISTs in the UGI tract. We compared patient demographic and tumour characteristics, operative procedures and postoperative outcomes. RESULTS In all, 207 patients undergoing gastrectomy or esophagectomy for non- GIST neoplasms were included. We identified 15 synchronous GISTs in the UGI tract of 11 (5.3%) patients (1 preoperatively, 4 intraoperatively and 10 on final pathology), with an average age of 67 years. Most patients were men. Additional resections were required for GISTs identified pre- or intraoperatively. Final pathology revealed completely resected c-kit positive tumours of an average size of 0.5 (range 0.1-4.0) cm with low or very low risk of malignant potential. No patients received adjuvant therapy for the GISTs. After a median follow-up of 11 (range 2-36) months, 5 patients died from their primary cancer, 3 were alive with primary cancer recurrence, and 3 were alive without disease. No patients experienced GIST recurrence. CONCLUSION Incidentally finding a synchronous GIST during resection of UGI neoplasms is not uncommon; it may alter surgical treatment but is unlikely to impact longterm survival.

Neutrophil extracellular traps sequester circulating tumor cells via β1-integrin mediated interactions

Despite advances in cancer treatment, metastasis remains today the main cause of cancer death. Local control through complete surgical resection of the primary tumor continues to be a key principle in cancer treatment. However, surgical interventions themselves lead to adverse oncologic outcomes and are associated with significantly increased rates of metastasis. Neutrophils through release of neutrophil extracellular traps (NETs) in response to infections were shown to be able to capture circulating cancer cells, and in doing so, support the development of metastatic disease. To be able to intervene on this process, understanding the exact molecular nature of these mechanisms is crucial. We therefore hypothesize and demonstrate that β1‐integrin is an important factor mediating the interactions between circulating tumor cells and NETs. We show that β1‐integrin expression on both cancer cells and NETs is important for the adhesion of circulating tumor cells to NETs both in vitro and in vivo. Using a murine model of intra‐abdominal sepsis to mimic the postoperative inflammatory environment, we show that β1‐integrin expression is upregulated in the context of inflammation in vivo. Ultimately, we show that this increased early cancer cell adhesion to NETs in vivo and this effect is abrogated when mice are administered DNAse 1. Our data therefore sheds light on the first molecular mechanism by which NETs can trap circulating tumor cells (CTCs), broadening our understanding of this process.

Secretion of hepatocyte growth factor and vascular endothelial growth factor during uveal melanoma-monocyte in vitro interactions.

Host–tumour interactions in uveal melanoma, and their involvement in the biological events leading to metastasis and eventually mortality, are not well understood. It is known that uveal melanoma disseminates predominantly via a haematogenous route with metastasis developing primarily in the liver. Therefore, cytokines involved in angiogenesis, such as vascular endothelial growth factor (VEGF), and those expressed in large quantities within the liver, such as hepatocyte growth factor (HGF), are of particular interest in uveal melanoma research. This study investigated the levels of HGF and VEGF in monocyte and uveal melanoma-conditioned medium. Five human uveal melanoma cell lines and one monocyte cell line were seeded in six-well plates. After 18 h, melanoma-conditioned medium (MCM) was placed on the monocyte cell line and monocyte-conditioned medium (MoCM) was placed on each uveal melanoma cell line. Tumour cells and monocytes incubated in fresh, as opposed to conditioned, medium after 18 h were used as controls. VEGF and HGF levels were determined by immunoassay prior to media transfer and 6, 12, 24 and 36 h thereafter. Both cytokines showed an upregulation of expression from all cells after incubation in conditioned medium. 28SC incubated in MCM expressed higher levels of the given cytokines than did uveal melanoma cells incubated in MoCM. In addition, each cell line exhibited a distinct pattern of expression, with individual cell lines exhibiting different peak levels of cytokine production at different time points. These results offer insight into the upregulation of VEGF and HGF, which may play a role in tumour–host cell interactions.