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Sarcomatoid mesothelioma is a rare, aggressive malignancy that usually follows asbestos exposure. It is the least common subtype of mesotheliomas, following epithelial and biphasic subtypes. Pleural mesothelioma can metastasize, with the liver, kidneys, adrenal glands, and opposite lungs being the most commonly reported sites for metastasis. Metastasis of the pancreas is extremely rare, which is why the authors of this case report intend to present the case of a 78-year-old male who was found to have acute pancreatitis, most likely secondary to metastatic lesions., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Al-Moussally et al.)

Purpose: The aim of this study is to characterize lung cancer treatment clinical trials in Latin America before (January 2001-December 2011) and after (January 2012-December 2021) the organization of major Latin American oncology cooperative groups., Materials and Methods: Interventional clinical trials were identified in ClinicalTrials.gov using the search terms "lung cancer," country filters for 20 Latin American countries, and study start dates January 1, 2001-December 31, 2011, and January 1, 2012-December 31, 2021. Clinical trials were categorized as either originating in Latin America (LA) or outside Latin America (non-LA) with participation of Latin American countries. Descriptive statistics, two-sided Z-scores, and chi-square analyses with 95% CIs were calculated., Results: Overall, 273 clinical trials involving Latin American countries between 2001 and 2021 were identified. Comparing 2001-2011 with 2012-2021, there was an increase in total clinical trials (100 v 173; P < .001). Only 9% (26 of 273) of all trials were LA trials. There was a marked decrease in the proportion of LA trials (14% v 7%, P = .058) and estimated enrollment to LA trials (3,245 v 1,190 patients; P < .001). Recruiting of patients with EGFR (29% v 7%; P < .01) and KRAS (18% v 2%; P < .01) driver mutations also decreased. Trial participation was highest in Brazil, Mexico, Argentina, Chile, and Peru and increased over time: Brazil (61 v 108; 77% increase), Mexico (40 v 88; 120% increase), Argentina (50 v 78; 56% increase), Chile (25 v 57; 128% increase), and Peru (14 v 37; 164% increase)., Conclusion: There was a significant increase in clinical trial participation by Latin American countries, from 2001-2011 to 2012-2021. However, there were few clinical trials which originated in Latin America or focused on patients with driver mutations.

Background: Research shows providing cancer patients with adequate information has many benefits, but how do nurse practitioners know whether the initial consultation meets the information needs of their patients? Furthermore, how can the initial consultation be improved?, Objective: A low-cost continuous quality improvement process centered on decreasing distress and increasing information satisfaction was piloted to determine its effectiveness and feasibility., Methods: Immediately before and after an initial consultation with a breast cancer surgeon, 59 women completed a questionnaire to measure distress and specific problems they were having. They then completed a questionnaire to measure information satisfaction. Pre-post changes in the distress score and number of problems were analyzed, as was information satisfaction. Feasibility was qualitatively examined., Results: For the study sample, pre-post median distress scores decreased significantly (from 5 to 3, Chi-square = 5.73, p < .017). Information dissatisfaction scales were identified. The process was deemed feasible., Conclusions: This effective and feasible process may help the nurse practitioner continuously improve the initial consultation process., Implications for Nursing: (a) the initial breast cancer consultation is important, (b) a novel process for improving the initial breast cancer consultation is proposed, and (c) this feasible, low-cost process should be embedded into normal practice operations., (© Copyright 2021 Springer Publishing Company, LLC.)

Purpose: To evaluate the rate and risk factors of isolated leptomeningeal progression in sinonasal carcinomas., Methods: We retrospectively reviewed imaging and clinical records to determine progression patterns, and estimated rates using the Kaplan-Meier method. We evaluated risk factors using proportional hazard regression., Results: We analyzed 120 patients who received adjuvant or primary radiotherapy for sinonasal carcinomas. Most patients had T4 disease (68%) and underwent surgery (84%) and chemotherapy (72%). Twenty-seven (23%) patients developed distant metastases (DM), including 20 (17%) with isolated DMs. Leptomeningeal progression was the most common site of isolated DMs (n = 9; 45%) with an average disease-free interval of 1.2 years (0.1-4.3 years). High-grade histology (P = 0.0003), intracranial invasion (P < 0.0001), and neuroendocrine histology (P = 0.06) were associated with increased risk., Conclusions: Isolated leptomeningeal progression is a common pattern of DM in advanced sinonasal carcinomas. We recommend adding cerebrospinal fluid cytology and contrast-enhanced spine MRI to routine staging evaluations for high-risk patients., (© 2019 Wiley Periodicals, Inc.)

The purpose of this quality improvement study was to improve physician documentation of distress in medical records of hematology/oncology veteran patients at the Malcolm Randall Veteran Affairs (VA) Medical Center hematology/oncology fellows' clinic in Gainesville, Florida. Before this intervention, the VA hematology/oncology fellows were not documenting patient distress in medical records. The quality improvement intervention was executed through the use of Plan-Do-Study-Act (PDSA) cycles with an ultimate goal of 50% documentation rate. Physician charts were audited to investigate official documentation of distress in patient charts. Physician documentation of distress was 14% in the first PDSA cycle, 21% in the second PDSA cycle, and 36% in the third PDSA cycle. Additional data on distress in hematology/oncology veteran patients were collected using the National Comprehensive Cancer Network Distress Thermometer and Problem List for Patients. Analysis of findings indicated that 42% of 88 patients experienced distress. Findings also suggest that hematology/oncology veteran patients experience specific sources of distress, notably fatigue and pain. These patients have presumably undergone unique experiences that can result in distress that providers should follow-up with in medical charts. Although this intervention has proven challenging to fully implement, standardizing patient distress in patient medical records has the potential to improve the quality of care provided by hematology/oncology physicians.

Aberrant activation of CDK4/6 kinase is the most common somatic event in non-small cell lung cancer (NSCLC). Palbociclib is a highly specific CDK4/6 inhibitor shown to inhibit cell cycle progression and promote cellular senescence. We conducted a phase 2 clinical trial of palbociclib in 19 previously-treated patients with advanced NSCLC. Only patients with p16-null staining by immunohistochemistry and documented tumor progression were eligible. The primary endpoint was tumor response rate. Palbociclib therapy alone was well-tolerated. Of 16 evaluable patients who received > 1 month of therapy, there were no objective responses. However, 8 patients (50%) with previously progressive NSCLC had stable disease (SD) lasting a range of 4-10.5 months. Median overall survival (OS) for all cases was 5.1 months, and median overall survival for the subset of patients with SD was 16.6 months. We also performed preclinical testing of palbociclib in combination with 13 different targeted or cytotoxic chemotherapeutic agents using a cell viability assay. Only the combination of palbociclib and mTOR inhibitors resulted in synergistic growth inhibition, particularly in tumors carrying RAS mutations. Our findings warrant further clinical investigation of the combination of palbociclib and mTOR inhibitors, especially in patients carrying activated RAS mutations., Competing Interests: CONFLICTS OF INTEREST Dr. Pinder-Schenck has received income from Merck and GlaxoSmithKline. Dr. Chiappori has received income from Genentech, Boehringer Ingelheim, Merck, Takeda, Bristol-Myers Squibb, Celgene, Astra Zeneca and Novartis. Mr. Gordillo has received income from Sangamo Therapeutics. All other authors have declared that no conflicts of interest exist.

We conducted a retrospective study of stereotactic ablative radiotherapy (SABR) for 94 patients with non-small-cell lung cancer at our institution. The patients were treated with either 50 Gy in five treatments or 48 Gy in four treatments, corresponding to biologically effective doses (BED) of 100 Gy or 105.6 Gy, respectively. The results demonstrate that, with relatively low BEDs, we can achieve excellent local control with minimal toxicity.

The European Society for Medical Oncology (ESMO) and the American Society of Clinical Oncology (ASCO) are publishing a new edition of the ESMO/ASCO Global Curriculum (GC) thanks to contribution of 64 ESMO-appointed and 32 ASCO-appointed authors. First published in 2004 and updated in 2010, the GC edition 2016 answers to the need for updated recommendations for the training of physicians in medical oncology by defining the standard to be fulfilled to qualify as medical oncologists. At times of internationalisation of healthcare and increased mobility of patients and physicians, the GC aims to provide state-of-the-art cancer care to all patients wherever they live. Recent progress in the field of cancer research has indeed resulted in diagnostic and therapeutic innovations such as targeted therapies as a standard therapeutic approach or personalised cancer medicine apart from the revival of immunotherapy, requiring specialised training for medical oncology trainees. Thus, several new chapters on technical contents such as molecular pathology, translational research or molecular imaging and on conceptual attitudes towards human principles like genetic counselling or survivorship have been integrated in the GC. The GC edition 2016 consists of 12 sections with 17 subsections, 44 chapters and 35 subchapters, respectively. Besides renewal in its contents, the GC underwent a principal formal change taking into consideration modern didactic principles. It is presented in a template-based format that subcategorises the detailed outcome requirements into learning objectives, awareness, knowledge and skills. Consecutive steps will be those of harmonising and implementing teaching and assessment strategies., Competing Interests: JBe received research support to Karolinska Institutet and University Hospital from Amgen, AstraZeneca, Bayer, Merck, Roche and Sanofi-Aventis. JBu received travel accommodations from Genentech/Roche. FC received a consultant honoraria in Astellas/Medivation, AstraZeneca, Celgene, Daiitchi-Sankyo, Eisai, GE Oncology, Genentech, GlaxoSmithKline (GSK), Merck-Scharp, Merus BV, Novartis, Pfizer, Pierre-Fabre, Roche, Sanofi, Teva. HC has worked in a consulting or advisory role in Amgen received speakers’ bureau in Baxalta, Celgene and received research funding from Celgene. PC received honoraria for consultancy/advisory role and/or for lectures from Bayer, Blueprint Medicines, Eisai, Eli Lilly, Glaxo SK, Merck SD, Merck Serono, Nektar Ther., Novartis, Pfizer, PharmaMar. AC received honoraria from MerckSerono, Roche, Amgen, Bayer, Lilly and speakers’ bureau from Roche and MerckSerono. RC received research funding from Genentech/Roche, Puma Biotechnology, Novartis and travel, accommodations, expenses from Novartis. LDP received fees as consultant or for lectures (no speakers’ bureau) from F. Hoffmann-La Roche, Pfizer, Bristol Meyer Squibb, AstraZeneca, Qiagen, Boehringer Ingelheim. All fees were paid to Institution. MDS received honoraria and consultation fees from Amgen, Astellas, Bayer, Celgene, Dendreon, Eisai Inc, ESSA, Ferring, GSK, Janssen Cilag, Merck, Novartis, Pfizer, Pierre Fabre Oncologie, Roche, Sanofi Aventis, Shionogi, Synthon, Takeda, Teva/OncoGenex; received research grant from Pierre Fabre Oncologie. EGEdV received research grants to the institute from Roche/Genentech, Amgen, Novartis, Pieris, Servier, is part of data monitoring committee in Biomarin and of advisory board in Synthon. CD received (un)restricted research grants donated to the research institute from Amgen, AstraZeneca, Bayer, Celgene, Eisai, Boehringer Ingelheim, Merck, MSD, Mundipharma, Novartis, Pfizer Corporation, PharmaMar, Pierre Fabre, Roche Austria, Sanofi-aventis, Takeda; received honoraria for consulting from AstraZeneca, Eli Lilly, Merck, Novartis Pharma, Roche Austria. DSD has worked in a consulting or advisory role for UpToDate and received research funding from Aeterna Zentaris (to Institution). LRD received research funding from GlaxoSmithKline (to Institution), Millennium (to Institution), Bristol-Myers Squibb (to Institution), Aeterna Zentaris (to Institution), Millenuim (to Institution) and has other relationship with Genentech. NES received honoraria from Roche, Novartis, MSD Oncology; received research funding from GlaxoSmithKline, Roche; received travel, accommodations, expenses from Novartis, Roche, Celgene. AE conduct research sponsored by Roche, GSK, Novartis, AstraZeneca, Celltrion, Apotex Inc. ME has stock and other ownership interests with Bristol-Myers Squibb, GE Healthcare, Nestle SA, Pfizer, CVS CAREMARK; has worked in a consulting or advisory role from Merck, Bristol-Myers Squibb, ALKERMES; received research funding from Altor BioScience, Bristol-Myers Squibb, Merck, Alkermes, Polynoma; received travel, accommodations, expenses from Myriad Genetics, Bristol-Myers Squibb, Merck. EF has worked as a consultant for Boehringer Ingelheim, Eli Lilly, Pfizer, Roche, BMS, MSD, Novartis; received speaker's bureau from Eli Lilly, BMS, Novartis. MFF has owned stock from Novartis. PKG research funding from Abbvie (to Institution) and Onyx (to Institution). AG has worked in a consulting or advisory role for Genentech/Roche (to Institution), Bayer (to Institution), Sanofi (to Institution), Bristol-Myers Squibb (to Institution), Lilly (to Institution), Boston Biomedical (to Institution), Amgen (to Institution); received research funding from Genentech/Roche (to Institution), Bayer (to Institution), Pfizer (to Institution), Eisai (to Institution), Sanofi (to Institution), Lilly (to Institution), Boston Biomedical (to Institution); received travel, accommodations, expenses from Genentech/Roche, Bayer, Bristol-Myers Squibb, Boston Biomedical, Amgen. SMH has stock and other ownership interests with Liquid Biotech, USA; has patents, royalties, other intellectual property with Liquid Biotech, USA. JH received advisory board and speaker fee from Tesaro and honorarium from SOBI. DVJ has worked in a consulting or advisory role for Bayer. UK received honoraria from Amgen, BMS, GSK, Glycotope, MerckSerono, Merck/MSD, Pfizer; received research support from Pfizer, MerckSerono, Innate, Sirtec. RK conduct research supported by Roche; a member of speaker's bureau of Roche, Meda, Novartis. SK received research funding from Novartis (to Institution), Merck (to Institution), Threshold Pharmaceuticals (to Institution), Gilead Sciences (to Institution), Bayer/Onyx (to Institution); received travel, accommodation, expenses from Novartis. C-HK received honoraria from Merck/Darmstadt, Amgen. MK is on speakers’ bureau for Astellas Pharma, Genentech/Roche, Sanofi, Lilly, Bayer; received research funding from Genentech/Roche (to Institution) and Merck Serono (to Institution). H-JL has received honoraria from Merck Serono, Roche, Celgene, Bayer, Boehringer Ingelheim; has served in a consulting or advisory role for Merck Serono, Roche, Bayer; received travel, accommodations, expenses from Merck Serono, Bayer, Roche. LL has served as a consultant/advisory for EISAI, BMS, MSD, Merck-Serono, Boehringer Ingelheim, DEBIOPHARM, SOBI, Novartis, AstraZeneca, Bayer and Roche; received research funds to institute for clinical studies from EISAI, MSD, Merck-Serono, Boehringer Ingelheim, Novartis, AstraZeneca and Roche; received travel coverage for medical meetings from Merck-Serono, DEBIOPHARM, SOBI, Bayer. PJL received research funding from Novartis (to Institution), Celgene (to Institution), ImClone Systems (to Institution), Taiho Pharmaceutical (to Institution); has patents, royalties, other intellectual property US PPA/61/499,988 Gene Expression Analysis of Thymic Neoplasms Inventors Sunil Badve, Yesim Gokmen-Polar, Patrick Loehrer (to Institution). RIL has served in consulting or advisory role for Roche, Novartis, Janssen; received speakers’ bureau from Roche, Novartis, Janssen. MJM received research funding from Astex Pharmaceuticals (to Institution). TN has ownership interest with Bioclassifier LLC; has role for invention of PAM50 breast cancer assay, which has been licensed to NanoString technologies and being marketed as Prosigna; has served as a consultant for NanoString. KÖ received speaker bureau from Novartis, Ipsen. PÖ received consulting fees, honoraria, travel grants or lecturing fees from Amgen, Bayer, Baxalta, Celgene, EliLilly, Merck, Nordic Drugs, Prime Oncology, Sanofi Oncology. AP received honoraria and consultancy fee from Amgen, Novartis, Bristol-Myers Squibb, Genmab A/S, Celgene, Janssen-Cilag, Millennium Pharmaceuticals, Onyx Pharmaceuticals, Sanofi Aventis. MR received honoraria from AstraZeneca; has served in a consulting or advisory role for Bayer, Pfizer, McKesson; received research funding from AstraZeneca (to Institution), AbbVie (to Institution), Myriad Genetics (to Institution), Biomarin (to Institution); received travel, accommodations, expenses from AstraZeneca, Biomarin. LS has served in a consulting or advisory role for bioTheranostics. MS conduct research sponsored by AstraZeneca, Bayer, Eisai, Exelixis, Genzyme. H-JS is an advisor for Roche, Bayer. LS has served in leadership for Eviti; has served in a consulting or advisory role for Merck; has patents, royalties, other intellectual property; as Co-Editor-in-Chief of UpToDate, Oncology. JS is an employee of Genentech; received honoraria, speakers’ bureau, travel, accommodations, expenses from Genentech. CNS received honoraria or research grant from Novartis, GSK, Pfizer, Merck, Lilly, BMS, Astellas, Bayer, Janssen, Sanofi. FS received unrestricted industry grants for clinical research from Celgene, Fresenius, Helsinn; FS participates in Novartis-lead clinical trials and received punctual advisorship (boards, expert meetings) from Acacia, ACRAF, Amgen, Baxter, Celgene, Danone, Fresenius, GlaxoSmithKline, Grünenthal, Helsinn, ISIS Global, Millennium/Takeda, Mundipharma, Novartis, Novelpharm, Nycomed, Obexia, Otsuka, Ono, Pharm-Olam, Pfizer, Psioxus, PrIME, Santhera, Sunstone, Teva, Vifor. RS received honoraria or consulting fee (paid to institution) from Roche, Merck KGaA/EMD-Serono, MSD/Merck & Co, Pfizer, Ipsen Pharma, Novartis. JT has worked in a consultant/advisory role for Amgen, Bayer, Boehringer Ingelheim, Celgene, Chugai, Lilly, MSD, Merck Serono, Novartis, Pfizer, Roche, Sanofi, Symphogen, Taiho and Takeda. EV has stock and other ownership interests with McKesson; has worked in a consulting or advisory role for Abbvie, AstraZeneca, Boehringer Ingelheim, Celgene, Clovis Oncology, GeneCentric, Genentech, Merck, Synta, VentiRx, Eisai, Lilly, Transgene; received speakers’ bureau for Amgen; received research funding from Abbvie (to Institution), Bristol-Myers Squibb (to Institution), Gen Vec Inc, (to Institution), Sanofi (to Institution), Monsanto (to Institution), Cyclacel (to Institution); received travel, accommodations, expenses from Amgen. JSW has stock and other ownership interests with Altor BioScience, Celldex, cCam Biotherapeutics; received honoraria from Bristol-Myers Squibb, Merck, Genentech, Abbvie, AstraZeneca, Daiichi Sankyo, GlaxoSmithKline, Eisai, Altor BioScience, Lion Biotechnologies, Amgen, Roche, Ichor Medical Systems, Celldex, cCam Biotherapeutics, Pieris; has worked in a consulting or advisory role for Celldex, Ichor Medical Systems, cCam Biotherapeutics, Lion Biotechnologies, Pieris, Altor BioScience, Bristol-Myers Squibb, Merck, Genentech, Roche, Amgen, AstraZeneca, GlaxoSmithKline, Daiichi Sankyo, Abbvie, Eisai; received research funding from Bristol-Myers Squibb (to Institution), Merck (to Institution), GlaxoSmithKline (to Institution), Genentech (to Institution), Astellas Pharma (to Institution), Incyte (to Institution), Roche (to Institution), Novartis (to Institution); received travel, accommodations, expenses from Bristol-Myers Squibb, GlaxoSmithKline, Daiichi Sankyo, Pieris, cCam Biotherapeutics, Lion Biotechnologies, Roche, Celldex, Amgen, Merck, AstraZeneca, Genentech.

Recent studies demonstrate that inflammatory signals regulate hematopoietic stem cells (HSCs). Granulocyte colony-stimulating factor (G-CSF) is often induced with infection and has a key role in the stress granulopoiesis response. However, its effects on HSCs are less clear. Herein, we show that treatment with G-CSF induces expansion and increased quiescence of phenotypic HSCs, but causes a marked, cell-autonomous HSC repopulating defect associated with induction of Toll-like receptor (TLR) expression and signaling. The G-CSF-mediated expansion of HSCs is reduced in mice lacking TLR2, TLR4 or the TLR signaling adaptor MyD88. Induction of HSC quiescence is abrogated in mice lacking MyD88 or in mice treated with antibiotics to suppress intestinal flora. Finally, loss of TLR4 or germ-free conditions mitigates the G-CSF-mediated HSC repopulating defect. These data suggest that low-level TLR agonist production by commensal flora contributes to the regulation of HSC function and that G-CSF negatively regulates HSCs, in part, by enhancing TLR signaling.

Detecting overlapping communities is essential to analyzing and exploring natural networks such as social networks, biological networks, and citation networks. However, most existing approaches do not scale to the size of networks that we regularly observe in the real world. In this paper, we develop a scalable approach to community detection that discovers overlapping communities in massive real-world networks. Our approach is based on a Bayesian model of networks that allows nodes to participate in multiple communities, and a corresponding algorithm that naturally interleaves subsampling from the network and updating an estimate of its communities. We demonstrate how we can discover the hidden community structure of several real-world networks, including 3.7 million US patents, 575,000 physics articles from the arXiv preprint server, and 875,000 connected Web pages from the Internet. Furthermore, we demonstrate on large simulated networks that our algorithm accurately discovers the true community structure. This paper opens the door to using sophisticated statistical models to analyze massive networks.

Background: Sunitinib is an oral multitargeted tyrosine kinase inhibitor, with single-agent activity in non-small cell lung cancer (NSCLC). Resistance to tyrosine kinase inhibitor therapy is mediated by the mammalian target of rapamycin (mTOR) pathway, and may be reversed by using mTOR inhibitors., Methods: We performed a phase I study evaluating the combination of sunitinib and rapamycin in patients with advanced NSCLC., Results: Nineteen patients were enrolled in the study. The dose-limiting toxicities included infection, pneumonia, diarrhea/dehydration and treatment delay due to thrombocytopenia in 1 patient each. Sunitinib 25 mg orally daily and rapamycin 2 mg orally daily with 4 weeks on and 2 weeks off therapy were determined to be the maximum tolerated dose. No objective responses were noted, and 6 patients had stable disease as a best response., Conclusion: The combination of sunitinib and rapamycin is well-tolerated and warrants further investigation in the phase II setting., (Copyright © 2013 S. Karger AG, Basel.)

Increased expression of Kruppel-like factor 7 (KLF7) is an independent predictor of poor outcome in pediatric acute lymphoblastic leukemia. The contribution of KLF7 to hematopoiesis has not been previously described. Herein, we characterized the effect on murine hematopoiesis of the loss of KLF7 and enforced expression of KLF7. Long-term multilineage engraftment of Klf7(-/-) cells was comparable with control cells, and self-renewal, as assessed by serial transplantation, was not affected. Enforced expression of KLF7 results in a marked suppression of myeloid progenitor cell growth and a loss of short- and long-term repopulating activity. Interestingly, enforced expression of KLF7, although resulting in multilineage growth suppression that extended to hematopoietic stem cells and common lymphoid progenitors, spared T cells and enhanced the survival of early thymocytes. RNA expression profiling of KLF7-overexpressing hematopoietic progenitors identified several potential target genes mediating these effects. Notably, the known KLF7 target Cdkn1a (p21(Cip1/Waf1)) was not induced by KLF7, and loss of CDKN1A does not rescue the repopulating defect. These results suggest that KLF7 is not required for normal hematopoietic stem and progenitor function, but increased expression, as seen in a subset of lymphoid leukemia, inhibits myeloid cell proliferation and promotes early thymocyte survival.

Neutrophils are a major component of the innate immune response. Their homeostasis is maintained, in part, by the regulated release of neutrophils from the bone marrow. Constitutive expression of the chemokine CXCL12 by bone marrow stromal cells provides a key retention signal for neutrophils in the bone marrow through activation of its receptor, CXCR4. Attenuation of CXCR4 signaling leads to entry of neutrophils into the circulation through unknown mechanisms. We investigated the role of CXCR2-binding ELR+ chemokines in neutrophil trafficking using mouse mixed bone marrow chimeras reconstituted with Cxcr2(-/-) and WT cells. In this context, neutrophils lacking CXCR2 were preferentially retained in the bone marrow, a phenotype resembling the congenital disorder myelokathexis, which is characterized by chronic neutropenia. Additionally, transient disruption of CXCR4 failed to mobilize Cxcr2(-/-) neutrophils. However, neutrophils lacking both CXCR2 and CXCR4 displayed constitutive mobilization, showing that CXCR4 plays a dominant role in neutrophil trafficking. With regard to CXCR2 ligands, bone marrow endothelial cells and osteoblasts constitutively expressed the ELR+ chemokines CXCL1 and CXCL2, and CXCL2 expression was induced in endothelial cells during G-CSF-induced neutrophil mobilization. Collectively, these data suggest that CXCR2 signaling is a second chemokine axis that interacts antagonistically with CXCR4 to regulate neutrophil release from the bone marrow.

This unit describes a hydrodynamic assay to study the relative importance of various receptor/ligand interactions in cell-cell and cell-substrate adhesion and to quantitate the strength of their binding. The basic protocol describes how to assemble the single-chamber flow system with the substrate, add the cells in suspension, and record the experiment on videotape. Alternate protocols present assays to determine how monoclonal antibodies and stimulating and inhibiting agents affect the substrate and the perfusing cells in suspension. Another alternate protocol details the use of the double-chamber flow system. Support protocols describe how to construct the single- and double-chamber flow systems and how to analyze the data from an experiment. Recording and analyzing the flow experiment requires the use of video equipment and, optionally, a computer and imaging software.

Neutrophils form CD18-dependent adhesions to endothelial cells at sites of inflammation. This phenomenon was investigated under conditions of flow in vitro using isolated human neutrophils and monolayers of HUVEC. The efficiency of conversion of neutrophil rolling to stable adhesion in this model was >95%. Neither anti-CD11a nor anti-CD11b antibodies significantly altered the extent of this conversion, but a combination of both antibodies inhibited the arrest of rolling neutrophils by >95%. The efficiency of transendothelial migration of arrested neutrophils was >90%, and the site of transmigration was typically <6 microm from the site of stationary adhesion. Approximately 70% of transmigrating neutrophils migrated at tricellular corners between three adjacent endothelial cells. A model of neutrophils randomly distributed on endothelium predicted a significantly greater migration distance to these preferred sites of transmigration, but a model of neutrophils adhering to endothelial borders is consistent with observed distances. It appears that stable adhesions form very near tricellular corners.

Neutrophil emigration through endothelial cells under shear flow involves several adhesion processes including cell rolling, arrest, and transmigration. Rolling is mediated by selectins, while arrest and transmigration both require activated CD18 integrins. One mode of CD18 activation is via selectins expressed on neutrophils and endothelial cells. We have recently reported that cross-linking of L-selectin (CD62L) resulted in the rapid activation of CD18-dependent adhesion. In the current study, we examine whether binding of E-selectin (CD62E) and L-selectin can activate neutrophil CD18-dependent adhesion under shear flow. Human ICAM-1 (CD54) and E-selectin were co-transfected into L cells. Neutrophil capture, rolling, and arrest on these monolayers were quantitated in a parallel plate flow chamber at a wall shear stress of 2.0 dyne/cm2. Under these conditions, E-selectin supported cell capture and rolling on the monolayer, but did not trigger CD18-mediated cell arrest within 200 microm of rolling. However, when neutrophils were treated with anti-L-selectin mAb and cross-linked with a secondary mAb, approximately 50% of the cells arrested within 54 microm. Cell arrest was also observed in response to IL-8 stimulation. A subthreshold level of IL-8 in combination with L-selectin cross-linking potentiated the level of cell arrest due to either stimulus alone. The transition to cell arrest involved both LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18). Blocking either subunit alone failed to reduce arrest, while blocking both molecules with mAbs reduced the number to baseline levels. These data support the conclusion that L-selectin, but not E-selectin, can signal the transition from neutrophil rolling to cell arrest under shear flow.

Emigration of leukocytes at sites of inflammation is initiated by the selectin family of carbohydrate-binding adhesion molecules. Molecular crossbridges initiate rolling of cells along the vascular endothelium where chemokines such as IL-8 and platelet activating factor (PAF) may be presented to their receptors on the leukocyte surface resulting in cell stimulation. Integrin activation appears to be a requirement for subsequent cell localization and diapedesis into the tissue. Several recent reports have demonstrated that ligation and cross-linking of neutrophil L-selectin results in neutrophil activation, including intracellular calcium release, superoxide production, and induction of mRNA for production of IL-8 and TNF-alpha. The purpose of this study was to examine whether ligation and cross-linking of L-selectin would specifically result in activation of beta 2-integrin-dependent adhesion. A fluorescence flow cytometric assay was developed that directly measures Mac-1-dependent cell adhesion. Fluorescent latex beads (2-microns diameter) were adsorbed with albumin or fibrinogen and added in excess to human neutrophils in a shear-stirred suspension. Following stimulation the kinetics of bead capture by neutrophils was continuously measured in real time on the flow cytometer. The onset of bead binding was detected in the presence of extremely low concentrations of PAF (10 pM) or formyl peptide (0.2 nM) stimulation. Ligation of L-selectin with whole IgG DREG200 or DREG56 Ab, but not controls (anti-CD44, -CD45, -CD11a), resulted in a significant potentiation of bead binding. Cross-linking F(ab')2 fragments of DREG200 with a goat anti-mouse F(ab')2 secondary Ab also stimulated beta 2-integrin-dependent adhesion in a dose-dependent fashion. A chimeric form of DREG200 expressing gamma 4 or gamma 1 isotypes of human Fc domain also stimulated cell adhesion when cross-linked. Surface expression of CD18 and an activation-dependent epitope, as detected with mAb24, also increased in response to L-selectin cross-linking. Cross-linking L-selectin induced significant adhesion and transmigration of neutrophils across human umbilical vein endothelial cells. We propose that cross-linking of L-selectin results in a cell signal that directly stimulates beta 2-integrin adhesive responses.