Beneficial impact of CCL2 and CCL12 neutralization on experimental malignant pleural effusion

The role of angiogenesis in malignant pleural effusion: from basic research to clinical application

Malignant pleural effusion (MPE) is associated with advanced stages of various malignant diseases, especially lung cancer, and is a poor prognostic indicator in these patients. However, the management of MPE remains palliative. A better understanding of the pathogenesis of MPE may lead to the development of new and more effective therapeutic options. Here, we shed light on recent advances in the mechanisms of MPE formation and provide an overview of current targeted therapies for the vascular endothelial growth factor pathway. We also retrospectively enrolled 19 patients with lung adenocarcinoma from the West China Hospital to analyze the efficacy of bevacizumab for MPE using different routes of administration.

Monocytes subtypes from pleural effusion reveal biomarker candidates for the diagnosis of tuberculosis and malignancy

Background

Pleural effusion is a common clinical condition caused by several respiratory diseases, including tuberculosis and malignancy. However, rapid and accurate diagnoses of tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE) remain challenging. Although monocytes have been confirmed as an important immune cell in tuberculosis and malignancy, little is known about the role of monocytes subpopulations in the diagnosis of pleural effusion.

Methods

Pleural effusion samples and peripheral blood samples were collected from 40 TPE patients, 40 MPE patients, and 24 transudate pleural effusion patients, respectively. Chemokines (CCL2, CCL7, and CX3CL1) and cytokines (IL‐1β, IL‐17, IL‐27, and IFN‐γ) were measured by ELISA. The monocytes phenotypes were analyzed by flow cytometry. The chemokines receptors (CCR2 and CX3CR1) and cytokines above in different monocytes subsets were analyzed by real‐time PCR. Receiver operating characteristic curve analysis was performed for displaying differentiating power of intermediate and nonclassical subsets between tuberculous and malignant pleural effusions.

Results

CCL7 and CX3CL1 levels in TPE were significantly elevated in TPE compared with MPE and transudate pleural effusion. Cytokines, such as IL‐1β, IL‐17, IL‐27, and IFN‐γ, in TPE were much higher than in other pleural effusions. Moreover, CD14⁺CD16⁺⁺ nonclassical subset frequency in TPE was remarkably higher than that in MPE, while CD14⁺⁺CD16⁺ intermediate subset proportion in MPE was found elevated. Furthermore, CX3CL1‐CX3CR1 axis‐mediated infiltration of nonclassical monocytes in TPE was related to CX3CL1 and IFN‐γ expression in TPE. Higher expression of cytokines (IL‐1β, IL‐17, IL‐27, and IFN‐γ) were found in nonclassical monocytes compared with other subsets. Additionally, the proportions of intermediate and nonclassical monocytes in pleural effusion have the power in discriminating tuberculosis from malignant pleural effusion.

Conclusions

CD14 and CD16 markers on monocytes could be potentially used as novel diagnostic markers for diagnosing TPE and MPE.

Role of chemokine systems in cancer and inflammatory diseases

Chemokines are a large family of small secreted proteins that have fundamental roles in organ development, normal physiology, and immune responses upon binding to their corresponding receptors. The primary functions of chemokines are to coordinate and recruit immune cells to and from tissues and to participate in regulating interactions between immune cells. In addition to the generally recognized antimicrobial immunity, the chemokine/chemokine receptor axis also exerts a tumorigenic function in many different cancer models and is involved in the formation of immunosuppressive and protective tumor microenvironment (TME), making them potential prognostic markers for various hematologic and solid tumors. In fact, apart from its vital role in tumors, almost all inflammatory diseases involve chemokines and their receptors in one way or another. Modulating the expression of chemokines and/or their corresponding receptors on tumor cells or immune cells provides the basis for the exploitation of new drugs for clinical evaluation in the treatment of related diseases. Here, we summarize recent advances of chemokine systems in protumor and antitumor immune responses and discuss the prevailing understanding of how the chemokine system operates in inflammatory diseases. In this review, we also emphatically highlight the complexity of the chemokine system and explore its potential to guide the treatment of cancer and inflammatory diseases.

CSF1/CSF1R signaling mediates malignant pleural effusion formation

Malignant pleural effusion (MPE) is an incurable common manifestation of many malignancies. Its formation is orchestrated by complex interactions among tumor cells, inflammatory cells, and the vasculature. Tumor-associated macrophages present the dominant inflammatory population of MPE, and M2 macrophage numbers account for dismal prognosis. M2 polarization is known to be triggered by CSF1/CSF1 receptor (CSF1R) signaling. We hypothesized that CSF1R⁺ M2 macrophages favor MPE formation and could be therapeutically targeted to limit MPE. We generated mice with CSF1R-deficient macrophages and induced lung and colon adenocarcinoma–associated MPE. We also examined the therapeutic potential of a clinically relevant CSF1R inhibitor (BLZ945) in lung and colon adenocarcinoma–induced experimental MPE. We showed that CSF1R⁺ macrophages promoted pleural fluid accumulation by enhancing vascular permeability, destabilizing tumor vessels, and favoring immune suppression. We also showed that CSF1R inhibition limited MPE in vivo by reducing vascular permeability and neoangiogenesis and impeding tumor progression. This was because apart from macrophages, CSF1R signals in cancer-associated fibroblasts leading to macrophage inflammatory protein 2 secretion triggered the manifestation of suppressive and angiogenic properties in macrophages upon CXCR2 paracrine activation. Pharmacological targeting of the CSF1/CSF1R axis can therefore be a vital strategy for limiting MPE.

An In Vivo Inflammatory Loop Potentiates KRAS Blockade

KRAS (KRAS proto-oncogene, GTPase) inhibitors perform less well than other targeted drugs in vitro and fail clinical trials. To investigate a possible reason for this, we treated human and murine tumor cells with KRAS inhibitors deltarasin (targeting phosphodiesterase-δ), cysmethynil (targeting isoprenylcysteine carboxylmethyltransferase), and AA12 (targeting KRAS^G12C), and silenced/overexpressed mutant KRAS using custom-designed vectors. We showed that KRAS-mutant tumor cells exclusively respond to KRAS blockade in vivo, because the oncogene co-opts host myeloid cells via a C-C-motif chemokine ligand 2 (CCL2)/interleukin-1 beta (IL-1β)-mediated signaling loop for sustained tumorigenicity. Indeed, KRAS-mutant tumors did not respond to deltarasin in C-C motif chemokine receptor 2 (Ccr2) and Il1b gene-deficient mice, but were deltarasin-sensitive in wild-type and Ccr2-deficient mice adoptively transplanted with wild-type murine bone marrow. A KRAS-dependent pro-inflammatory transcriptome was prominent in human cancers with high KRAS mutation prevalence and poor predicted survival. Our findings support that in vitro cellular systems are suboptimal for anti-KRAS drug screens, as these drugs function to suppress interleukin-1 receptor 1 (IL1R1) expression and myeloid IL-1β-delivered pro-growth effects in vivo. Moreover, the findings support that IL-1β blockade might be suitable for therapy for KRAS-mutant cancers.

Deficiency in CCR2 increases susceptibility of mice to infection with an intracellular pathogen, Francisella tularensis LVS, but does not impair development of protective immunity

CCR2 is the major chemokine receptor that regulates appropriate trafficking of inflammatory monocytes, but the role of this chemokine receptor and its ligands during primary and secondary infection with intracellular infections remains incompletely understood. Here we used murine infection with the Live Vaccine Strain (LVS) of Francisella tularensis to evaluate the role of CCR2 during primary and secondary parenteral responses to this prototype intracellular bacterium. We find that mice deficient in CCR2 are highly compromised in their ability to survive intradermal infection with LVS, indicating the importance of this receptor during primary parenteral responses. Interestingly, this defect could not be readily attributed to the activities of the known murine CCR2 ligands MCP-1/CCL2, MCP-3/CCL7, or MCP-5/CCL12. Nonetheless, CCR2 knockout mice vaccinated by infection with low doses of LVS generated optimal T cell responses that controlled the intramacrophage replication of Francisella, and LVS-immune CCR2 knockout mice survived maximal lethal Francisella challenge. Thus, fully protective adaptive immune memory responses to this intracellular bacterium can be readily generated in the absence of CCR2.

Host Wnt5a Potentiates Microenvironmental Regulation of Ovarian Cancer Metastasis

The noncanonical Wnt ligand Wnt5a is found in high concentrations in ascites of women with ovarian cancer. In this study, we elucidated the role of Wnt5a in ovarian cancer metastasis. Wnt5a promoted ovarian tumor cell adhesion to peritoneal mesothelial cells as well as migration and invasion, leading to colonization of peritoneal explants. Host components of the ovarian tumor microenvironment, notably peritoneal mesothelial cells and visceral adipose, secreted Wnt5a. Conditional knockout of host WNT5A significantly reduced peritoneal metastatic tumor burden. Tumors formed in WNT5A knockout mice had elevated cytotoxic T cells, increased M1 macrophages, and decreased M2 macrophages, indicating that host Wnt5a promotes an immunosuppressive microenvironment. The Src family kinase Fgr was identified as a downstream effector of Wnt5a. These results highlight a previously unreported role for host-expressed Wnt5a in ovarian cancer metastasis and suggest Fgr as a novel target for inhibition of ovarian cancer metastatic progression.Significance: This study establishes host-derived Wnt5a, expressed by peritoneal mesothelial cells and adipocytes, as a primary regulator of ovarian cancer intraperitoneal metastatic dissemination and identifies Fgr kinase as novel target for inhibition of metastasis.

Immuno-PET identifies the myeloid compartment as a key contributor to the outcome of the antitumor response under PD-1 blockade

Immunotherapy using checkpoint-blocking antibodies against PD-1 has produced impressive results in a wide range of cancers. However, the response remains heterogeneous among patients. We used noninvasive immuno-positron emission tomography (PET), using ⁸⁹Zr-labeled PEGylated single-domain antibody fragments (nanobodies or VHHs), to explore the dynamics and distribution of intratumoral CD8⁺ T cells and CD11b⁺ myeloid cells in response to anti-PD-1 treatment in the MC38 colorectal mouse adenocarcinoma model. Responding and nonresponding tumors showed consistent differences in the distribution of CD8⁺ and CD11b⁺ cells. Anti-PD-1 treatment mobilized CD8⁺ T cells from the tumor periphery to a more central location. Only those tumors fully infiltrated by CD8⁺ T cells went on to complete resolution. All tumors contained CD11b⁺ myeloid cells from the outset of treatment, with later recruitment of additional CD11b⁺ cells. As tumors grew, the distribution of intratumoral CD11b⁺ cells became more heterogeneous. Shrinkage of tumors in responders correlated with an increase in the CD11b⁺ population in the center of the tumors. The changes in distribution of CD8⁺ and CD11b⁺ cells, as assessed by PET, served as biomarkers to gauge the efficacy of anti-PD-1 treatment. Single-cell RNA sequencing of RNA from intratumoral CD45⁺ cells showed that CD11b⁺ cells in responders and nonresponders were markedly different. The responders exhibited a dominant population of macrophages with an M1-like signature, while the CD45⁺ population in the nonresponders displayed an M2-like transcriptional signature. Thus, by using immuno-PET and single-cell RNA sequencing, we show that anti-PD-1 treatment not only affects interactions of CD8⁺ T cells with the tumor but also impacts the intratumoral myeloid compartment.

Prolonged retention of liposomes in the pleural cavity of normal mice and high tumor distribution in mice with malignant pleural effusion, after intrapleural injection

Background: Intrapleural administration of compounds is a lung targeted, innovative therapeutic strategy for mesothelioma, which can be refined as a route for drug delivery that minimizes the potential for systemic toxicity. However, little is currently known about the retention of liposomal drugs at the site, after such topical administration. Purpose: To evaluate the retention of liposomes in lungs following intrapleural injection, and how this might be modulated by liposome properties and disease progression. Methods: DiR-incorporating liposomes with various lipid compositions and sizes were prepared, characterized (for size distribution and zeta potential) and injected intrapleurally in normal mice and mice with malignant pleural effusion (MPE). DiR retention in pleural cavity was followed by biofluorescence imaging. Results: Experimental results demonstrate that liposome size and PEG-coating, have a significant effect on residence time in the pleural cavity; negative surface charge does not. More than 20% liposomal-DiR is retained 24 d post-injection (in some cases), indicating the high potential towards localized diseases. Ex-vivo liposomal-DiR signal in tumors of MPE mice was similar to signal in liver, suggesting high tumor targeting potential of intrapleurally injected liposomes. Finally, no difference was noticed in liposomal-DiR retention between tumor-inoculated (MPE) and healthy mice, indicating the stability of liposomes in the presence of effusion (in MPE mice). Conclusion: The current study provides novel insights for using liposomes by intrapleural administration for the treatment of lung diseases.

Stimulations of the Culture Medium of Activated Microglia and TNF-Alpha on a Scrapie-Infected Cell Line Decrease the Cell Viability and Induce Marked Necroptosis That Also Occurs in the Brains from the Patients of Human Prion Diseases

Activation of microglia and increased expression of TNF-α are frequently observed in the brains of human and animal prion diseases. As an important cytokine, TNF-α participates in not only pro-inflammatory responses but also in cellular communication, cell differentiation, and cell death. However, the role of TNF-α in the pathogenesis of prion disease remains ambiguous. In this study, the activities of a scrapie-infected cell line SMB-S15 and its normal partner SMB-PS exposed to the supernatant of a LPS-activated microglia cell line BV2 were evaluated. After it was exposed to the LPS-stimulated supernatant of BV2 cells, the cell viability of SMB-S15 cells was markedly decreased, whereas that of the SMB-PS cells remained unchanged. The level of TNF-α was significantly increased in the LPS-stimulated supernatant of BV2 cells. Further, we found that the recombinant TNF-α alone induced the decreased cell viability of SMB-S15 and the neutralizing antibody for TNF-α completely antagonized the decreased cell viability caused by the LPS-stimulated supernatant of BV2 cells. Stimulation with TNF-α induced the remarkable increases of apoptosis-associated proteins in SMB-PS cells, such as cleaved caspase-3 and RIP1, whereas an obvious increase of necroptosis-associated protein in SMB-S15 cells, such as p-MLKL. Meanwhile, the upregulation of caspase-8 activity in SMB-PS cells was more significant than that of SMB-S15 cells. The decreased cell viability of SMB-S15 and the increased expression of p-MLKL induced by TNF-α were completely rescued by Necrostatin-1. Moreover, we verified that removal of PrP^Sc propagation in SMB-S15 cells by resveratrol partially rescues the cell tolerance to the stimulation of TNF-α. These data indicate that the prion-infected cell line SMB-S15 is more vulnerable to the stimulations of activated microglia and TNF-α, which is likely due to the outcome of necroptosis rather than apoptosis. Furthermore, significant upregulation of p-MLKL, MLKL, and RIP3 was detected in the post-mortem cortical brains of the patients of various types of human prion diseases, including sporadic Creutzfeldt-Jakob disease (sCJD), G114 V-genetic CJD (gCJD), and fatal familial insomnia (FFI).

Migrated T lymphocytes into malignant pleural effusions: an indicator of good prognosis in lung adenocarcinoma patients

The presence of leukocyte subpopulations in malignant pleural effusions (MPEs) can have a different impact on tumor cell proliferation and vascular leakiness, their analysis can help to understand the metastatic microenvironment. We analyzed the relationship between the leukocyte subpopulation counts per ml of pleural fluid and the tumor cell count, molecular phenotype of lung adenocarcinoma (LAC), time from cancer diagnosis and previous oncologic therapy. We also evaluated the leukocyte composition of MPEs as a biomarker of prognosis. We determined CD4+ T, CD8+ T and CD20+ B cells, monocytes and neutrophils per ml in pleural effusions of 22 LAC and 10 heart failure (HF) patients by flow cytometry. Tumor cells were identified by morphology and CD326 expression. IFNγ, IL-10 and IL-17, and chemokines were determined by ELISAs and migratory response to pleural fluids by transwell assays. MPEs from LAC patients had more CD8+ T lymphocytes and a tendency to more CD4+ T and CD20+ B lymphocytes than HF-related fluids. However, no correlation was found between lymphocytes and tumor cells. In those MPEs which were detected >1 month from LAC diagnosis, there was a negative correlation between pleural tumor cells and CD8+ T lymphocytes. CXCL10 was responsible for the attraction of CD20+ B, CD4+ T and CD8+ T lymphocytes in malignant fluids. Concentrations of IL-17 were higher in MPEs than in HF-related effusions. Survival after MPE diagnosis correlated positively with CD4+ T and CD8+ T lymphocytes, but negatively with neutrophils and IL-17 levels. In conclusion, lymphocyte enrichment in MPEs from LAC patients is mostly due to local migration and increases patient survival.

Myeloid-derived interleukin-1β drives oncogenic KRAS-NF-κΒ addiction in malignant pleural effusion

Malignant pleural effusion (MPE) is a frequent metastatic manifestation of human cancers. While we previously identified KRAS mutations as molecular culprits of MPE formation, the underlying mechanism remained unknown. Here, we determine that non-canonical IKKα-RelB pathway activation of KRAS-mutant tumor cells mediates MPE development and this is fueled by host-provided interleukin IL-1β. Indeed, IKKα is required for the MPE-competence of KRAS-mutant tumor cells by activating non-canonical NF-κB signaling. IL-1β fuels addiction of mutant KRAS to IKKα resulting in increased CXCL1 secretion that fosters MPE-associated inflammation. Importantly, IL-1β-mediated NF-κB induction in KRAS-mutant tumor cells, as well as their resulting MPE-competence, can only be blocked by co-inhibition of both KRAS and IKKα, a strategy that overcomes drug resistance to individual treatments. Hence we show that mutant KRAS facilitates IKKα-mediated responsiveness of tumor cells to host IL-1β, thereby establishing a host-to-tumor signaling circuit that culminates in inflammatory MPE development and drug resistance.

NRAS destines tumor cells to the lungs

The lungs are frequently affected by cancer metastasis. Although NRAS mutations have been associated with metastatic potential, their exact role in lung homing is incompletely understood. We cross-examined the genotype of various tumor cells with their ability for automatic pulmonary dissemination, modulated NRAS expression using RNA interference and NRAS overexpression, identified NRAS signaling partners by microarray, and validated them using Cxcr1- and Cxcr2-deficient mice. Mouse models of spontaneous lung metastasis revealed that mutant or overexpressed NRAS promotes lung colonization by regulating interleukin-8-related chemokine expression, thereby initiating interactions between tumor cells, the pulmonary vasculature, and myeloid cells. Our results support a model where NRAS-mutant, chemokine-expressing circulating tumor cells target the CXCR1-expressing lung vasculature and recruit CXCR2-expressing myeloid cells to initiate metastasis. We further describe a clinically relevant approach to prevent NRAS-driven pulmonary metastasis by inhibiting chemokine signaling. In conclusion, NRAS promotes the colonization of the lungs by various tumor types in mouse models. IL-8-related chemokines, NRAS signaling partners in this process, may constitute an important therapeutic target against pulmonary involvement by cancers of other organs.

Danshen improves survival of patients with colon cancer and dihydroisotanshinone I inhibit the proliferation of colon cancer cells via apoptosis and skp2 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Danshen (Salvia miltiorrhiza Bunge) is widely used in traditional Chinese medicine. However, it's definite clinical effect and mechanism on colon carcinoma is unclear.

AIM OF THE STUDY

To test the hypothesis that the protective effect of danshen on colon cancer and discover the bioactive compounds through in vitro study.

MATERIALS AND METHODS

We conducted a nationwide cohort study by using population-based data from the Taiwan National Health Insurance Research Database (NHIRD). The study cohort comprised patients diagnosed with malignant neoplasm of colon (ICD-9-CM codes:153) in catastrophic illness database between January 1, 2000, and December 31, 2010. We used the Kaplan-Meier method to estimate colon [corrected] cancer cumulative incidences. Next, human colon cancer cells (HCT 116 cells and HT29 cells) were used to investigate the effect of dihydroisotanshinone I (DT) on the proliferation and apoptosis of human colon cancer cells and the underlying mechanism through XTT assay and flow cytometry. The in vivo effect of DT treatment was investigated through a xenograft nude mouse model.

RESULTS

In our study, the in vivo protective effect of danshen in the different stage of colon cancer patients was validated through data from the National Health Insurance Research Database in Taiwan. In vitro, we found that dihydroisotanshinone I (DT), a bioactive compound present in danshen, can inhibit the proliferation of colon carcinoma cells, HCT 116 cells and HT-29 cells. Moreover, DT induced apoptosis of colorectal cancer cells. DT also repressed the protein expression of Skp2 (S-Phase Kinase Associated Protein 2) and the mRNA levels of its related gene, Snail1 (Zinc finger protein SNAI1) and RhoA (Ras homolog gene family, member A). In addition, DT also blocked the colon cancer cells recruitment ability of macrophage by decreasing CCL2 secretion in macrophages. DT treatment also significantly inhibited the final tumor volume in a xenograft nude mouse model.

CONCLUSION

Danshen has protective effects in colon cancer patients, which could be attributed to DT through blocking the proliferation of colon cancer cells through apoptosis.

Mutant KRAS promotes malignant pleural effusion formation

Malignant pleural effusion (MPE) is the lethal consequence of various human cancers metastatic to the pleural cavity. However, the mechanisms responsible for the development of MPE are still obscure. Here we show that mutant KRAS is important for MPE induction in mice. Pleural disseminated, mutant KRAS bearing tumour cells upregulate and systemically release chemokine ligand 2 (CCL2) into the bloodstream to mobilize myeloid cells from the host bone marrow to the pleural space via the spleen. These cells promote MPE formation, as indicated by splenectomy and splenocyte restoration experiments. In addition, KRAS mutations are frequently detected in human MPE and cell lines isolated thereof, but are often lost during automated analyses, as indicated by manual versus automated examination of Sanger sequencing traces. Finally, the novel KRAS inhibitor deltarasin and a monoclonal antibody directed against CCL2 are equally effective against an experimental mouse model of MPE, a result that holds promise for future efficient therapies against the human condition.

Toxicogenomic analysis of the pulmonary toxic effects of hexanal in F344 rat

Hexanal is a major component of indoor air pollutants and is a kind of aldehydes; it has adverse effects on human health. We performed an in vivo inhalation study and transcriptomic analysis to determine the mode of toxic actions in response to hexanal. Fischer 344 rats of both sexes were exposed by inhalation to hexanal aerosol for 4 h day^-1 , 5 days week^-1 for 4 weeks at 0, 600, 1000, and 1500 ppm. Throughout our microarray-based genome-wide expression analysis, we identified 56 differentially expressed genes in three doses of hexanal; among these genes, 11 genes showed dose-dependent expression patterns (10 downregulated and 1 upregulated, 1.5-fold, p < 0.05). Through a comparative toxicogenomics database (CTD) analysis of 11 genes, we determined that five genes (CCL12, DDIT4, KLF2, CEBPD, and ADH6) are linked to diverse disease categories such as cancer, respiratory tract disease, and immune system disease. These diseases were previously known for being induced by volatile organic compounds (VOCs). Our data demonstrated that the hexanal-induced dose-dependent altered genes could be valuable quantitative biomarkers to predict hexanal exposure and to perform relative risk assessments, including pulmonary toxicity. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 382-396, 2017.

Role of MCP-1 in pleural effusion development in a carrageenan-induced murine model of pleurisy

BACKGROUND AND OBJECTIVE

Exudative pleural effusions affect over 1500 patients per million population each year. The pathobiology of pleural exudate formation remains unclear. Our recent study revealed monocyte chemotactic protein-1 (MCP-1) as a key driver of fibrinolytic-induced exudate effusion while another study found a role for MCP-1 in malignant effusion formation. In the present study, we further evaluated the role of MCP-1 in the development of pleural effusion in a mouse model of acute pleural inflammation.

METHODS

λ-Carrageenan (CAR) was injected into the pleural cavity of CD1 mice and pleural effusion volume measured up to 16 h post-injection. Pleural effusion and serum protein and MCP-1 concentrations were measured and differential cell counts performed in fluids. Mice were also treated with either intraperitoneal (i) anti-MCP-1 antibody or isotype control or (ii) an MCP-1 receptor (CCR2) antagonist or vehicle control 12 h prior to and at the time of CAR injection.

RESULTS

Intrapleural CAR induced significant pleural fluid accumulation (300.0 ± 49.9 μL) in mice after 4 h. Pleural fluid MCP-1 concentrations were significantly higher than corresponding serum MCP-1 (144 603 ± 23 204 pg/mL vs 3703 ± 801 pg/mL, P < 0.0001). A significant decrease in pleural fluid formation was seen both with anti-MCP-1 antibody (median (interquartile range, IQR): 36 (0-168) μL vs controls 290 (70-436) μL; P = 0.02) or CCR2 antagonist (153 (30-222) μL vs controls 240 (151-331) μL, P = 0.0049).

CONCLUSIONS

Blockade of MCP-1 activity significantly reduced inflammatory pleural effusion formation in a CAR model. Together with recent successes in MCP-1 blockade in other effusion formation models, our data strongly support clinical evaluation of MCP-1 antagonists as a novel approach to pleural fluid management.

Tumor-derived osteopontin isoforms cooperate with TRP53 and CCL2 to promote lung metastasis

The lungs are ubiquitous receptacles of metastases originating from various bodily tumors. Although osteopontin (SPP1) has been associated with tumor dissemination, the role of its isoforms in lung-directed metastasis is incompletely understood. We employed syngeneic mouse models of spontaneous and induced lung-targeted metastasis in C57BL/6 mice competent and deficient in both Spp1 alleles. Tumor-derived osteopontin expression was modulated using either stable anti-Spp1 RNA interference, or forced overexpression of intracellular and secreted Spp1 isoforms. Identified osteopontin's downstream partners were validated using lung adenocarcinoma cells conditionally lacking the Trp53 gene and Ccr2-deficient mice. We determined that host-derived osteopontin was dispensable for pulmonary colonization by different tumor types. Oppositely, tumor-originated intracellular osteopontin promoted tumor cell survival by preventing tumor-related protein 53-mediated apoptosis, while the secretory osteopontin functioned in a paracrine mode to accelerate lung metastasis by enhancing tumor-derived C-C-motif chemokine ligand 2 signaling to cognate host receptors. As new ways to target osteopontin signaling are becoming available, the cytokine may constitute an important therapeutic target against pulmonary involvement by cancers of other organs.

The Role of Chemokines in Promoting Colorectal Cancer Invasion/Metastasis

Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. Although most of the primary CRC can be removed by surgical resection, advanced tumors sometimes show recurrences in distant organs such as the liver, lung, lymph node, bone or peritoneum even after complete resection of the primary tumors. In these advanced and metastatic CRC, it is the tumor-stroma interaction in the tumor microenvironment that often promotes cancer invasion and/or metastasis through chemokine signaling. The tumor microenvironment contains numerous host cells that may suppress or promote cancer aggressiveness. Several types of host-derived myeloid cells reside in the tumor microenvironment, and the recruitment of them is under the control of chemokine signaling. In this review, we focus on the functions of chemokine signaling that may affect tumor immunity by recruiting several types of bone marrow-derived cells (BMDC) to the tumor microenvironment of CRC.

Longitudinal Measurement of Pleural Fluid Biochemistry and Cytokines in Malignant Pleural Effusions

BACKGROUND

Malignant pleural effusion (MPE) is common. Existing literature on pleural fluid compositions is restricted to cross-sectional sampling with little information on longitudinal changes of fluid biochemistry and cytokines with disease progression. Indwelling pleural catheters provide the unique opportunity for repeated sampling and longitudinal evaluation of MPE, which may provide insight into tumor pathobiology.

METHODS

We collected 638 MPE samples from 103 patients managed with indwelling pleural catheters over 95 days (median, range 0-735 days) and analyzed them for protein, pH, lactate dehydrogenase, and glucose levels. Peripheral blood was quantified for hematocrit, platelets, leukocytes, protein, and albumin. Cytokine levels (monocyte chemotactic protein [MCP]-1; vascular endothelial growth factor; interleukin-6, -8, and -10; tumor necrosis factor-α; and interferon-gamma) were determined in 298 samples from 35 patients with mesothelioma. Longitudinal changes of all parameters were analyzed using a linear mixed model.

RESULTS

Significant decreases were observed over time in pleural fluid protein by 8 g/L per 100 days (SE, 1.32; P < .0001) and pH (0.04/100 days; SE, 0.02; P = .0203), accompanied by a nonsignificant rise in lactate dehydrogenase. The ratio of pleural fluid to serum protein decreased by 0.06/100 days (SE, 0.02; P = .04). MPEs from mesothelioma (n = 63) had lower pleural fluid glucose (P = .0104) at baseline and a faster rate of decline in glucose (P = .0423) when compared with non-mesothelioma effusions (n = 38). A progressive rise in mesothelioma pleural fluid concentration of [log] MCP-1 ([log] 0.37 pg/mL per 100 days; SE, 0.13; P = .0046), but not of other cytokines, was observed.

CONCLUSIONS

MPE fluids become less exudative and more acidic over the disease course. The rise in MCP-1 levels suggests a pathobiological role in MPE.

Tissue plasminogen activator potently stimulates pleural effusion via a monocyte chemotactic protein-1-dependent mechanism

Pleural infection is common. Evacuation of infected pleural fluid is essential for successful treatment, but it is often difficult because of adhesions/loculations within the effusion and the viscosity of the fluid. Intrapleural delivery of tissue plasminogen activator (tPA) (to break the adhesions) and deoxyribonuclease (DNase) (to reduce fluid viscosity) has recently been shown to improve clinical outcomes in a large randomized study of pleural infection. Clinical studies of intrapleural fibrinolytic therapy have consistently shown subsequent production of large effusions, the mechanism(s) of which are unknown. We aimed to determine the mechanism by which tPA induces exudative fluid formation. Intrapleural tPA, with or without DNase, significantly induced pleural fluid accumulation in CD1 mice (tPA alone: median [interquartile range], 53.5 [30-355] μl) compared with DNase alone or vehicle controls (both, 0.0 [0.0-0.0] μl) after 6 hours. Fluid induction was reproduced after intrapleural delivery of streptokinase and urokinase, indicating a class effect. Pleural fluid monocyte chemotactic protein (MCP)-1 levels strongly correlated with effusion volume (r = 0.7302; P = 0.003), and were significantly higher than MCP-1 levels in corresponding sera. Mice treated with anti-MCP-1 antibody (P < 0.0001) or MCP-1 receptor antagonist (P = 0.0049) demonstrated a significant decrease in tPA-induced pleural fluid formation (by up to 85%). Our data implicate MCP-1 as the key molecule governing tPA-induced fluid accumulation. The role of MCP-1 in the development of other exudative effusions warrants examination.

EGFR-L858R mutant enhances lung adenocarcinoma cell invasive ability and promotes malignant pleural effusion formation through activation of the CXCL12-CXCR4 pathway

Malignant pleural effusion (MPE) is a common clinical problem in non-small cell lung carcinoma (NSCLC) patients; however, the underlying mechanisms are still largely unknown. Recent studies indicate that the frequency of the L858R mutant form of the epidermal growth factor receptor (EGFR-L858R) is higher in lung adenocarcinoma with MPE than in surgically resected specimens, suggesting that lung adenocarcinoma cells harboring this mutation tend to invade the adjacent pleural cavity. The purpose of this study was to clarify the relationship between the EGFR-L858R mutation and cancer cell invasion ability and to investigate the molecular mechanisms involved in the formation of MPE. We found that expression of EGFR-L858R in lung cancer cells resulted in up-regulation of the CXCR4 in association with increased cancer cell invasive ability and MPE formation. Ectopic expression of EGFR-L858R in lung cancer cells acted through activation of ERK signaling pathways to induce the expression of CXCR4. We also indicated that Inhibition of CXCR4 with small interfering RNA, neutralizing antibody, or receptor antagonist significantly suppressed the EGFR-L858R–dependent cell invasion. These results suggest that targeting the production of CXCR4 and blocking the CXCL12-CXCR4 pathway might be effective strategies for treating NSCLCs harboring a specific type of EGFR mutation.

Switching off malignant pleural effusion formation-fantasy or future?

Malignant pleural effusion (MPE) is common and difficult to treat. In the vast majority of patients the presence of MPE heralds incurable disease, associated with poor quality of life, morbidity and mortality. Current therapeutic approaches are inefficient and merely offer palliation of associated symptoms. Recent scientific progress has shed light in the biologic processes governing the mechanisms behind the pathobiology of MPE. Pleural based tumors interfere with pleural fluid drainage, as well as the host vasculature and immune system, resulting in decreased fluid absorption and increased pleural fluid production via enhanced plasma extravasation into the pleural space. In order to achieve this feat, pleural based tumors must elicit critical vasoactive events in the pleura, thus forming a favorable microenvironment for tumor dissemination and MPE development. Such properties involve specific transcriptional signaling cascades in addition to secretion of important mediators which attract and activate host cell populations which, in turn, impact tumor cell functions. The dissection of the biologic steps leading to MPE formation provides novel therapeutic targets and recent research findings provide encouraging results towards future therapeutic innovations in MPE management.

Pleural involvement in lung cancer

The pleural space, a sterile secluded environment in the thoracic cavity, represents an attractive metastatic site for various cancers of lung, breast and gastrointestinal origins. Whereas lung and breast adenocarcinomas could invade the pleural space because of their anatomic proximity, "distant" cancers like ovarian or gastrointestinal tract adenocarcinomas may employ more active mechanisms to the same end. A pleural metastasis is often accompanied by a malignant pleural effusion (MPE), an unfavorable complication that severely restricts the quality of life and expectancy of the cancer patient. MPE is the net "product" of three different processes, namely inflammation, enhanced angiogenesis and vascular leakage. Current efforts are focusing on the identification of cancer cell autocrine (specific mutation spectra and biochemical pathways) and paracrine (cytokine and chemokine signals) characteristics as well as host features (immunological or other) that underlie the MPE phenotype. Herein we examine the pleural histology, cytology and molecular characteristics that make the pleural cavity an attractive metastasis destination for lung adenocarcinoma. Mesothelial and tumor features that may account for the tumor's ability to invade the pleural space are highlighted. Finally, possible therapeutic interventions specifically targeting MPE are discussed.

Mast cells mediate malignant pleural effusion formation

Mast cells (MCs) have been identified in various tumors; however, the role of these cells in tumorigenesis remains controversial. Here, we quantified MCs in human and murine malignant pleural effusions (MPEs) and evaluated the fate and function of these cells in MPE development. Evaluation of murine MPE-competent lung and colon adenocarcinomas revealed that these tumors actively attract and subsequently degranulate MCs in the pleural space by elaborating CCL2 and osteopontin. MCs were required for effusion development, as MPEs did not form in mice lacking MCs, and pleural infusion of MCs with MPE-incompetent cells promoted MPE formation. Once homed to the pleural space, MCs released tryptase AB1 and IL-1β, which in turn induced pleural vasculature leakiness and triggered NF-κB activation in pleural tumor cells, thereby fostering pleural fluid accumulation and tumor growth. Evaluation of human effusions revealed that MCs are elevated in MPEs compared with benign effusions. Moreover, MC abundance correlated with MPE formation in a human cancer cell-induced effusion model. Treatment of mice with the c-KIT inhibitor imatinib mesylate limited effusion precipitation by mouse and human adenocarcinoma cells. Together, the results of this study indicate that MCs are required for MPE formation and suggest that MC-dependent effusion formation is therapeutically addressable.

Lung cancer coexisting with ipsilateral pleural effusion

SUMMARY 

Invasion beyond the elastic layer of the visceral pleura and/or diffuse pleural metastatic spread affects negatively survival in lung cancer. Presence of pleural effusion is also associated with poor prognosis, and image techniques can be of great help for diagnosis. When pleural fluid cytology is negative, thoracoscopy is advisable before attempting tumor resection, in order to detect unsuspected pleural metastases. If widespread pleural malignancy is confirmed, chemical pleurodesis using graded talc (with particles larger than 20 µm in diameter) is the best option, unless the lung is unable to re-expand. In this case, or when a previous pleurodesis has failed, or there is a short life expectancy, placement of a indwelling pleural catheter is the treatment of choice.

Monoclonal antibody targeting of mononuclear cell chemokines driving malignant pleural effusion

Recent evidence suggests that host immune cells contribute to the development of malignant pleural effusion (MPE), a common manifestation of metastatic cancer. We have identified such cells, predominantly mononuclear myeloid cells, recruited by tumor-orchestrated inflammatory chemokines. Moreover, targeting of these inflammation-associated mediators modified the disease course of MPE in mice.