High-dimensional deconstruction of pancreatic cancer identifies tumor microenvironmental and developmental stemness features that predict survival.

Numerous cell states are known to comprise the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME). However, the developmental stemness and co-occurrence of these cell states remain poorly defined. Here, we performed single-cell RNA sequencing (scRNA-seq) on a cohort of treatment-naive PDAC time-of-diagnosis endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) samples (n = 25). We then combined these samples with surgical resection (n = 6) and publicly available samples to increase statistical power (n = 80). Following annotation into 25 distinct cell states, cells were scored for developmental stemness, and a customized version of the Ecotyper tool was used to identify communities of co-occurring cell states in bulk RNA-seq samples (n = 268). We discovered a tumor microenvironmental community comprised of aggressive basal-like malignant cells, tumor-promoting SPP1+ macrophages, and myofibroblastic cancer-associated fibroblasts associated with especially poor prognosis. We also found a developmental stemness continuum with implications for survival that is present in both malignant cells and cancer-associated fibroblasts (CAFs). We further demonstrated that high-dimensional analyses predictive of survival are feasible using standard-of-care, time-of-diagnosis EUS-FNB specimens. In summary, we identified tumor microenvironmental and developmental stemness characteristics from a high-dimensional gene expression analysis of PDAC using human tissue specimens, including time-of-diagnosis EUS-FNB samples. These reveal new connections between tumor microenvironmental composition, CAF and malignant cell stemness, and patient survival that could lead to better upfront risk stratification and more personalized upfront clinical decision-making.

Outcomes of endoscopic treatment of leaks and fistulae after sleeve gastrectomy: results from a large multicenter U.S. cohort.

BACKGROUND: Sleeve gastrectomy is the most commonly performed bariatric surgery in the United States. Leaks after sleeve gastrectomy (SGL) occur in 1% to 3% of patients. Endoscopic therapies are increasingly used for treatment of SGLs, but few data exist on their outcomes. OBJECTIVES: The aim of this study was to assess technical success, leak resolution, and reoperation rates of patients undergoing endoscopic therapy for repair SGLs. SETTING: Eight high-volume academic endoscopy centers. METHODS: Patients undergoing endoscopic therapy for SGLs from 2007 to 2017 were identified. Patients were excluded if the index endoscopic therapy for SGL was performed elsewhere or if no follow-up data were available. Leaks were classified as acute (≤7 d of SG), early (1-6 wk), late (7-12 wk), and chronic (>12 wk). Leak resolution was defined as lack of extraluminal air, extravasation on oral contrast radiography, cross-sectional imaging, or resolution of percutaneous drain output. Demographic and procedural data were recorded as rates of additional therapy, adverse events, and surgical revision. RESULTS: A total of 85 patients met criteria for analysis (70 women, age 42.6 ± 10.8 yr). A total of 295 endoscopic sessions (median 3, range 1-14) were performed across the cohort. SGLs resolved after index endoscopic therapy in 43 (50.1%) patients. The primary outcome of endoscopic resolution of SGL was observed in 62 patients (72.9%). There were 34 (11.5%) PRAE (the majority occurring with self-expandable metal stents), all but 1 of which were managed endoscopically. Surgical revision was required in 23 (21.7%) patients. On univariate analyses independent variables associated with the need for surgical revision included both acute and chronic SGLs (P = .028), loculated subphrenic collections/abscesses (P = .03), and intraabdominal sepsis (P = .03). On multivariable logistic regression using statistically significant predictors from the univariate analyses, acute SGLs were significantly associated with a need for surgical revision (odds ratio 4.8, 95% confidence interval 1.2-18.9, P = .025). CONCLUSION: Endoscopic therapy for SGLs is associated with good clinical success, avoiding the need for surgical revision in 73% of patients, with an acceptable adverse event profile. Patients with acute or chronic SGLs and those with loculated abscesses or intraabdominal sepsis are more likely to undergo surgical revision. Endoscopic therapy is an appropriate first-line modality for the management of SGLs, especially those not classified as acute or chronic.

Anatomic location of Barrett's esophagus recurrence after endoscopic eradication therapy: development of a simplified surveillance biopsy strategy.

BACKGROUND AND AIMS: Surveillance endoscopy is recommended after endoscopic eradication therapy (EET) for Barrett's esophagus (BE) because of the risk of recurrence. Currently recommended biopsy protocols are based on expert opinion and consist of sampling visible lesions followed by random 4-quadrant biopsy sampling throughout the length of the original BE segment. Despite this protocol, some recurrences are not visibly identified. We aimed to identify the anatomic location and histology of recurrences after successful EET with the goal of developing a more efficient and evidence-based surveillance biopsy protocol. METHODS: We performed an analysis of a large multicenter database of 443 patients who underwent EET and achieved complete eradication of intestinal metaplasia (CE-IM) from 2005 to 2015. The endoscopic location of recurrence relative to the squamocolumnar junction (SCJ), visible recurrence identified during surveillance endoscopy, and time to recurrence after CE-IM were assessed. RESULTS: Fifty patients with BE recurrence were studied in the final analysis. Seventeen patients (34%) had nonvisible recurrences. In this group, biopsy specimens demonstrating recurrence were taken from within 2 cm of the SCJ in 16 of these 17 patients (94%). Overall, 49 of 50 recurrences (98%) occurred either within 2 cm of the SCJ or at the site of a visible lesion. Late recurrences (>1 year) were more likely to be visible than early (<1 year) recurrences (P = .006). CONCLUSIONS: Recurrence after EET detected by random biopsy sampling is identified predominately in the distal esophagus and occurs earlier than visible recurrences. As such, we suggest a modified biopsy protocol with targeted sampling of visible lesions followed by random biopsy sampling within 2 cm of the SCJ to optimize detection of recurrence after EET. (Clinical trial registration number: NCT02634645.).

A randomized controlled trial evaluating general endotracheal anesthesia versus monitored anesthesia care and the incidence of sedation-related adverse events during ERCP in high-risk patients.

BACKGROUND AND AIMS: ERCP is a complex procedure often performed in patients at high risk for sedation-related adverse events (SRAEs). However, there is no current standard of care with regard to mode of sedation and airway management during ERCP. The aim of this study was to assess the safety of general endotracheal anesthesia (GEA) versus propofol-based monitored anesthesia care (MAC) without endotracheal intubation in patients undergoing ERCP at high risk for SRAEs. METHODS: Consecutive patients undergoing ERCP at high risk for SRAEs at a single center were invited to participate in this randomized controlled trial comparing GEA and MAC. Inclusion criteria were STOP-BANG score ≥3, abdominal ascites, body mass index ≥35, chronic lung disease, American Society of Anesthesiologists class >3, Mallampati class 4 airway, and moderate to heavy alcohol use. Exclusion criteria were preceding EUS, emergent ERCP, tracheostomy, unstable airway, gastric outlet obstruction or delayed gastric emptying, and altered foregut anatomy. The primary endpoint was composite incidence of SRAEs: hypoxemia, use of airway maneuvers, hypotension requiring vasopressors, sedation-related procedure interruption, cardiac arrhythmia, and respiratory failure. Secondary outcomes included procedure duration, cannulation success, in-room time, and immediate adverse events. RESULTS: Two hundred patients (mean age, 61.1 ± 13.6 years; 36.5% women) were randomly assigned to GEA (n = 101) or MAC (n = 99) groups. Composite SRAEs were significantly higher in the MAC group compared with the GEA group (51.5% vs 9.9%, P < .001). This was primarily driven by the frequent need for airway maneuvers in the MAC group. Additionally, ERCP was interrupted in 10.1% of patients in the MAC group to convert to GEA because of respiratory instability refractory to airway maneuvers (n = 8) or significant retained gastric contents (n = 2). There were no statistically significant differences in cannulation, in-room, procedure, or fluoroscopy times between the 2 groups. All patients undergoing GEA were successfully extubated in the procedure room at completion of ERCP, and Aldrete scores in recovery did not differ between the 2 groups. There were no immediate adverse events. CONCLUSION: In patients at high risk for SRAEs undergoing ERCP, sedation with GEA is associated with a significantly lower incidence of SRAEs, without impacting procedure duration, success, recovery, or in-room time. These data suggest that GEA should be used for ERCP in patients at high risk for SRAEs (Clinical trial registration number: NCT02850887.).

Health-related quality of life and long-term outcomes after endoscopic therapy for walled-off pancreatic necrosis.

BACKGROUND AND AIM: Walled-off pancreatic necrosis (WON) frequently develops after necrotizing pancreatitis. Endoscopic drainage has become the preferred modality for symptomatic or infected WON. The aim of the present study was to assess health-related quality of life (HR-QOL) and long-term outcomes in patients undergoing endoscopic drainage for WON. METHODS: Patients undergoing endoscopic drainage of WON from January 2006 to May 2016 were identified. Data recorded included demographic information, and the incidence of long-term sequelae including pancreatic endocrine and exocrine insufficiency. Attempts were made to contact all patients. HR-QOL was assessed using the SF-36 questionnaire. RESULTS: Eighty patients were analyzed, 41 (51.3%) of whom completed the SF-36. One-year all-cause mortality was 6.2%, and disease-related mortality was 3.7%. A notable proportion of patients developed exocrine insufficiency (32.5%), endocrine insufficiency (27.7%), and long-term opiate use (42.5%). Development of exocrine insufficiency was predictive of lower total SF-36 scores (P = 0.016). Patients with WON had better HR-QOL compared with cohorts of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). In patients developing exocrine insufficiency versus healthy controls, poorer scores in the physical role (P < 0.001), general health (P < 0.001), vitality (P = 0.001), and emotional role (P = 0.029) domains were observed. Exocrine insufficiency patients had better HR-QOL than the IBS and IBD cohorts, although these differences were less pronounced. CONCLUSION: After undergoing endoscopic drainage for WON, patients have relatively preserved HR-QOL. The subset of patients that develop exocrine insufficiency have significantly poorer HR-QOL compared to healthy controls, although not to the degree of chronic gastrointestinal disorders such as IBS and IBD.

The importance of early recognition in management of ERCP-related perforations.

BACKGROUND: Iatrogenic perforations related to endoscopic retrograde cholangiopancreatography (ERCP) are rare events, carrying with it a mortality of up to 8%. Given the rarity of this adverse event, there remains limited data and continued uncertainties when choosing therapeutic strategies. Our aims were to evaluate the management of ERCP-related perforations and compare outcomes based on timing of recognition. METHODS: The endoscopic databases of two tertiary care centers were interrogated to identify consecutive adult patients who sustained ERCP-related perforation over a 10-year period from 2006 to 2016. Electronic medical records were reviewed to extract demographic data, perforation type, management strategies, clinical data, and patient outcomes. RESULTS: 14,045 ERCP's were performed during our 10-year study period. Sixty-three patients (average age 62.3 ± 2.38 years, 76% female) with ERCP-related perforations were included. Stapfer I perforations were found in 14 (22.2%) patients, Stapfer II in 24 (38.1%), and Stapfer III and IV perforations were identified in 16 (25.4%) and 9 (14.28%), respectively. Forty-seven (74.6%) perforations were recognized immediately during the ERCP, whereas 16 (25.4%) were recognized late. Endoscopic therapy was attempted in 35 patients in whom perforations were identified immediately, and was technically successful in 33 (94.3%). In all, 4 (1 immediate/ 3 delayed) patients required percutaneous drainage and 9 (5 immediate/ 4 delayed) surgery. Length of hospital stay, ICU admission were significantly shorter and incidence of SIRS was significantly lower when perforation was recognized immediately. CONCLUSIONS: Immediate recognition of ERCP-related perforations leads to more favorable patient outcomes; with lower incidence of SIRS, less need for ICU level care, and shorter hospital stay.

Utility of Endoscopic Ultrasound in Evaluating Local Recurrence After Surgery for Pancreatic Cancer.

Pancreatic adenocarcinoma recurrence after surgery (PARaS) is associated with poor outcomes. PARaS is locoregional in 50%-80%, effecting the resection bed and adjacent lymphatics.1-3 Detection of PARaS via endoscopic ultrasound (EUS) is challenging because recurrent malignancy is difficult to distinguish from normal postoperative changes. Diagnosing PARaS is important, because salvage chemotherapy/radiation improves survival.4,5 The purpose of this investigation is to determine the clinical utility of EUS fine-needle aspiration (FNA) in patients with suspected PARaS.

Percutaneous transhepatic vs. endoscopic retrograde biliary drainage for suspected malignant hilar obstruction: study protocol for a randomized controlled trial.

BACKGROUND: The optimal approach to the drainage of malignant obstruction at the liver hilum remains uncertain. We aim to compare percutaneous transhepatic biliary drainage (PTBD) to endoscopic retrograde cholangiography (ERC) as the first intervention in patients with cholestasis due to suspected malignant hilar obstruction (MHO). METHODS: The INTERCPT trial is a multi-center, comparative effectiveness, randomized, superiority trial of PTBD vs. ERC for decompression of suspected MHO. One hundred and eighty-four eligible patients across medical centers in the United States, who provide informed consent, will be randomly assigned in 1:1 fashion via a web-based electronic randomization system to either ERC or PTBD as the initial drainage and, if indicated, diagnostic procedure. All subsequent clinical interventions, including crossover to the alternative procedure, will be dictated by treating physicians per usual clinical care. Enrolled subjects will be assessed for successful biliary drainage (primary outcome measure), adequate tissue diagnosis, adverse events, the need for additional procedures, hospitalizations, and oncological outcomes over a 6-month follow-up period. Subjects, treating clinicians and outcome assessors will not be blinded. DISCUSSION: The INTERCPT trial is designed to determine whether PTBD or ERC is the better initial approach when managing a patient with suspected MHO, a common clinical dilemma that has never been investigated in a randomized trial. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier: NCT03172832 . Registered on 1 June 2017.

EUS-guided drainage of peripancreatic fluid collections with lumen-apposing metal stents and plastic double-pigtail stents: comparison of efficacy and adverse event rates.

BACKGROUND AND AIMS: Transmural drainage with double-pigtail plastic stents (DPPSs) was the mainstay of endoscopic therapy for symptomatic peripancreatic fluid collections (PPFCs) until the introduction of lumen-apposing covered self-expanding metal stents (LAMSs). Currently, there are limited data regarding the efficacy and adverse event rate of LAMSs compared with DPPSs. METHODS: A retrospective analysis of EUS-guided PPFC drainage at a single tertiary care center between 2008 and 2015 was performed. Patients were classified based on drainage method: DPPSs and LAMSs. Adverse event rates, unplanned endoscopic procedures/necrosectomies, and PPFC resolution within 6 months were recorded. Significant bleeding was defined as necessitating transfusion or requiring endoscopic treatment/radiographic embolization. Subsequent endoscopic procedures were defined as unplanned procedures; stent removals were excluded. RESULTS: A total of 103 patients met inclusion criteria (84 DPPSs, 19 LAMSs). PPFCs were classified as walled-off necrosis (WON) in 23 (14 DPPSs, 9 LAMSs). There were significantly more bleeding episodes in the LAMS group (4 [19%]: 2 splenic artery pseudo-aneurysms, 1 collateral vessel bleed, 1 intracavitary variceal bleed; P = .0003) than in the DPPS group (1 (1%]: stent erosion into the gastric wall). One perforation occurred in the DPPS group. Unplanned repeat endoscopy was more frequent in the LAMS group (10% vs 26%, P = .07). Among retreated LAMS patients in with WON, 5 (56%) had obstruction by necrotic debris. In patients for whom follow-up was available, 67 of 70 (96%) with DPPSs and 16 of 17 (94%) with LAMSs had resolution of PPFCs within 6 months (P = .78). CONCLUSIONS: DPPSs and LAMSs are effective methods for treatment of PPFCs. In our cohort, use of LAMSs was associated with significantly higher rates of procedure-related bleeding and greater need for repeat endoscopic intervention.

Successful Treatment of Ulcerative Colitis With Vedolizumab in a Patient With an Infliximab-Associated Psoriasiform Rash.

Psoriatic skin lesions associated with anti-tumor necrosis factor (TNF) agents are well-described in the medical literature. However, the etiology and optimal management of this condition remain unclear. Vedolizumab is a novel, gut-specific, anti-integrin agent used for the treatment of inflammatory bowel disease (IBD). We report a case of infliximab-associated psoriasiform lesions in an ulcerative colitis patient. Transition to vedolizumab resulted in resolution of the cutaneous lesions without recurrence and remission of his ulcerative colitis.

A single-center experience of endoscopic submucosal dissection performed in a Western setting.

BACKGROUND: Compared with the piecemeal resection associated with endoscopic mucosal resection, endoscopic submucosal dissection (ESD) enables en bloc resection of larger lesions, allows for more accurate histological assessments, and has reduced recurrence rates. ESD is not widely performed in Western countries given increased technical difficulty, high complication rates, and long procedure times. AIMS: To evaluate the safety and efficacy of ESD in a single center in the USA. METHODS: A retrospective study on a prospectively collected database identified cases in which a single operator (IW) performed ESD at a tertiary referral center. Twenty cases were identified, nine in the upper digestive tract (four esophagus and five stomach) and 11 in the lower digestive tract (nine rectal and two sigmoid colon). Data regarding lesion location, pathology, method of ESD (composition/volume of lifting injection and resection method), post-procedure complications, and margin involvement were collected. RESULTS: En bloc resection was obtained in 14/20 patients (70 %). The average procedure time was 202 min in the esophagus, 148 min in the stomach, and 106 min for lower lesions. A major complication (perforation) occurred in 1/20 cases (5 %). Complete resection was obtained in 14/20 (70 %). R0 resection was obtained in 16/20 (80 %) cases. CONCLUSIONS: The complication, en bloc resection, and complete resection rates of this study are similar to those found in large studies on ESD performed in Eastern settings. ESD is safe and efficacious for en bloc resections of pre-malignant and early-invasive lesions, and should be offered to patients with suitable lesions in Western settings.

Particulate matter air pollution disrupts endothelial cell barrier via calpain-mediated tight junction protein degradation.

BACKGROUND: Exposure to particulate matter (PM) is a significant risk factor for increased cardiopulmonary morbidity and mortality. The mechanism of PM-mediated pathophysiology remains unknown. However, PM is proinflammatory to the endothelium and increases vascular permeability in vitro and in vivo via ROS generation. OBJECTIVES: We explored the role of tight junction proteins as targets for PM-induced loss of lung endothelial cell (EC) barrier integrity and enhanced cardiopulmonary dysfunction. METHODS: Changes in human lung EC monolayer permeability were assessed by Transendothelial Electrical Resistance (TER) in response to PM challenge (collected from Ft. McHenry Tunnel, Baltimore, MD, particle size >0.1 µm). Biochemical assessment of ROS generation and Ca2+ mobilization were also measured. RESULTS: PM exposure induced tight junction protein Zona occludens-1 (ZO-1) relocation from the cell periphery, which was accompanied by significant reductions in ZO-1 protein levels but not in adherens junction proteins (VE-cadherin and ß-catenin). N-acetyl-cysteine (NAC, 5 mM) reduced PM-induced ROS generation in ECs, which further prevented TER decreases and atteneuated ZO-1 degradation. PM also mediated intracellular calcium mobilization via the transient receptor potential cation channel M2 (TRPM2), in a ROS-dependent manner with subsequent activation of the Ca2+-dependent protease calpain. PM-activated calpain is responsible for ZO-1 degradation and EC barrier disruption. Overexpression of ZO-1 attenuated PM-induced endothelial barrier disruption and vascular hyperpermeability in vivo and in vitro. CONCLUSIONS: These results demonstrate that PM induces marked increases in vascular permeability via ROS-mediated calcium leakage via activated TRPM2, and via ZO-1 degradation by activated calpain. These findings support a novel mechanism for PM-induced lung damage and adverse cardiovascular outcomes.

Particulate matter induces cardiac arrhythmias via dysregulation of carotid body sensitivity and cardiac sodium channels.

The mechanistic links between exposure to airborne particulate matter (PM) pollution and the associated increases in cardiovascular morbidity and mortality, particularly in people with congestive heart failure (CHF), have not been identified. To advance understanding of this issue, genetically engineered mice (CREB(A133)) exhibiting severe dilated cardiomyopathic changes were exposed to ambient PM collected in Baltimore. CREB(A133) mice, which display aberrant cardiac physiology and anatomy reminiscent of human CHF, displayed evidence of basal autonomic aberrancies (compared with wild-type mice) with PM exposure via aspiration, producing significantly reduced heart rate variability, respiratory dysynchrony, and increased ventricular arrhythmias. Carotid body afferent nerve responses to hypoxia and hyperoxia-induced respiratory depression were pronounced in PM-challenged CREB(A133) mice, and denervation of the carotid bodies significantly reduced PM-mediated cardiac arrhythmias. Genome-wide expression analyses of CREB(A133) left ventricular tissues demonstrated prominent Na(+) and K(+) channel pathway gene dysregulation. Subsequent PM challenge increased tyrosine phosphorylation and nitration of the voltage-gated type V cardiac muscle α-subunit of the Na(+) channel encoded by SCN5A. Ranolazine, a Na(+) channel modulator that reduces late cardiac Na(+) channel currents, attenuated PM-mediated cardiac arrhythmias and shortened PM-elongated QT intervals in vivo. These observations provide mechanistic insights into the epidemiologic findings in susceptibility of human CHF populations to PM exposure. Our results suggest a multiorgan pathobiology inherent to the CHF phenotype that is exaggerated by PM exposure via heightened carotid body sensitivity and cardiac Na(+) channel dysfunction.

Particulate matter disrupts human lung endothelial barrier integrity via ROS- and p38 MAPK-dependent pathways.

Epidemiologic studies have linked exposure to airborne pollutant particulate matter (PM) with increased cardiopulmonary mortality and morbidity. The mechanisms of PM-mediated lung pathophysiology, however, remain unknown. We tested the hypothesis that PM, via enhanced oxidative stress, disrupts lung endothelial cell (EC) barrier integrity, thereby enhancing organ dysfunction. Using PM collected from Ft. McHenry Tunnel (Baltimore, MD), we assessed PM-mediated changes in transendothelial electrical resistance (TER) (a highly sensitive measure of barrier function), reactive oxygen species (ROS) generation, and p38 mitogen-activated protein kinase (MAPK) activation in human pulmonary artery EC. PM induced significant dose (10-100 microg/ml)- and time (0-10 h)-dependent EC barrier disruption reflected by reduced TER values. Exposure of human lung EC to PM resulted in significant ROS generation, which was directly involved in PM-mediated EC barrier dysfunction, as N-acetyl-cysteine (NAC, 5 mM) pretreatment abolished both ROS production and barrier disruption induced by PM. Furthermore, PM induced p38 MAPK activation and HSP27 phosphorylation, events that were both attenuated by NAC. In addition, PM-induced EC barrier disruption was partially prevented by the p38 MAP kinase inhibitor SB203580 (10 microM) as well as by reduced expression of either p38 MAPK beta or HSP27 (siRNA). These results demonstrate that PM induces ROS generation in human lung endothelium, resulting in oxidative stress-mediated EC barrier disruption via p38 MAPK- and HSP27-dependent pathways. These findings support a novel mechanism for PM-induced lung dysfunction and adverse cardiopulmonary outcomes.

Murine lung responses to ambient particulate matter: genomic analysis and influence on airway hyperresponsiveness.

BACKGROUND: Asthma is a complex disease characterized by airway hyperresponsiveness (AHR) and chronic airway inflammation. Epidemiologic studies have demonstrated that exposures to environmental factors such as ambient particulate matter (PM), a major air pollutant, contribute to increased asthma prevalence and exacerbations. OBJECTIVE: We investigated pathophysiologic responses to Baltimore, Maryland, ambient PM (median diameter, 1.78 mum) in a murine model of asthma and attempted to identify PM-specific genomic/molecular signatures. METHODS: We exposed ovalbumin (OVA)-sensitized A/J mice intratracheally to PM (20 mg/kg), and assayed both AHR and bronchoalveolar lavage (BAL) on days 1, 4, and 7 after PM exposure. Lung gene expression profiling was analyzed in OVA- and PM-challenged mice. RESULTS: Consistent with this murine model of asthma, we observed significant increases in airway responsiveness in OVA-treated mice, with PM exposure inducing significant changes in AHR in both naive mice and OVA-induced asthmatic mice. PM evoked eosinophil and neutrophil infiltration into airways, elevated BAL protein content, and stimulated secretion of type 1 T helper (T(H)1) cytokines [interferon-gamma, interleukin-6 (IL-6), tumor necrosis factor-alpha] and T(H)2 cytokines (IL-4, IL-5, eotaxin) into murine airways. Furthermore, PM consistently induced expression of genes involved in innate immune responses, chemotaxis, and complement system pathways. CONCLUSION: This study is consistent with emerging epidemiologic evidence and indicates that PM exposure evokes proinflammatory and allergic molecular signatures that may directly contribute to the asthma susceptibility in naive subjects and increased severity in affected asthmatics.

Essential role of pre-B-cell colony enhancing factor in ventilator-induced lung injury.

RATIONALE: We previously demonstrated pre-B-cell colony enhancing factor (PBEF) as a biomarker in sepsis and sepsis-induced acute lung injury (ALI) with genetic variants conferring ALI susceptibility. OBJECTIVES: To explore mechanistic participation of PBEF in ALI and ventilator-induced lung injury (VILI). METHODS: Two models of VILI were utilized to explore the role of PBEF using either recombinant PBEF or PBEF(+/-) mice. MEASUREMENTS AND MAIN RESULTS: Initial in vitro studies demonstrated recombinant human PBEF (rhPBEF) as a direct rat neutrophil chemotactic factor with in vivo studies demonstrating marked increases in bronchoalveolar lavage (BAL) leukocytes (PMNs) after intratracheal injection in C57BL/6J mice. These changes were accompanied by increased BAL levels of PMN chemoattractants (KC and MIP-2) and modest increases in lung vascular and alveolar permeability. We next explored the potential synergism between rhPBEF challenge (intratracheal) and a model of limited VILI (4 h, 30 ml/kg tidal volume) and observed dramatic increases in BAL PMNs, BAL protein, and cytokine levels (IL-6, TNF-alpha, KC) compared with either challenge alone. Gene expression profiling identified induction of ALI- and VILI-associated gene modules (nuclear factor-kappaB, leukocyte extravasation, apoptosis, Toll receptor pathways). Heterozygous PBEF(+/-) mice were significantly protected (reduced BAL protein, BAL IL-6 levels, peak inspiratory pressures) when exposed to a model of severe VILI (4 h, 40 ml/kg tidal volume) and exhibited significantly reduced expression of VILI-associated gene expression modules. Finally, strategies to reduce PBEF availability (neutralizing antibody) resulted in significant protection from VILI. CONCLUSIONS: These studies implicate PBEF as a key inflammatory mediator intimately involved in both the development and severity of ventilator-induced ALI.