Vessel co‐option is common in human lung metastases and mediates resistance to anti‐angiogenic therapy in preclinical lung metastasis models

Anti‐angiogenic therapies have shown limited efficacy in the clinical management of metastatic disease, including lung metastases. Moreover, the mechanisms via which tumours resist anti‐angiogenic therapies are poorly understood. Importantly, rather than utilizing angiogenesis, some metastases may instead incorporate pre‐existing vessels from surrounding tissue (vessel co‐option). As anti‐angiogenic therapies were designed to target only new blood vessel growth, vessel co‐option has been proposed as a mechanism that could drive resistance to anti‐angiogenic therapy. However, vessel co‐option has not been extensively studied in lung metastases, and its potential to mediate resistance to anti‐angiogenic therapy in lung metastases is not established. Here, we examined the mechanism of tumour vascularization in 164 human lung metastasis specimens (composed of breast, colorectal and renal cancer lung metastasis cases). We identified four distinct histopathological growth patterns (HGPs) of lung metastasis (alveolar, interstitial, perivascular cuffing, and pushing), each of which vascularized via a different mechanism. In the alveolar HGP, cancer cells invaded the alveolar air spaces, facilitating the co‐option of alveolar capillaries. In the interstitial HGP, cancer cells invaded the alveolar walls to co‐opt alveolar capillaries. In the perivascular cuffing HGP, cancer cells grew by co‐opting larger vessels of the lung. Only in the pushing HGP did the tumours vascularize by angiogenesis. Importantly, vessel co‐option occurred with high frequency, being present in >80% of the cases examined. Moreover, we provide evidence that vessel co‐option mediates resistance to the anti‐angiogenic drug sunitinib in preclinical lung metastasis models. Assuming that our interpretation of the data is correct, we conclude that vessel co‐option in lung metastases occurs through at least three distinct mechanisms, that vessel co‐option occurs frequently in lung metastases, and that vessel co‐option could mediate resistance to anti‐angiogenic therapy in lung metastases. Novel therapies designed to target both angiogenesis and vessel co‐option are therefore warranted. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Nanotherapy silencing the interleukin‐8 gene produces regression of prostate cancer by inhibition of angiogenesis

Interleukin‐8 (IL‐8) is a pro‐angiogenic cytokine associated with aggressive prostate cancer (CaP). We detected high levels of IL‐8 in sera from patients with CaP compared with healthy controls and patients with benign prostatic hypertrophy. This study examines the role of IL‐8 in the pathogenesis of metastatic prostate cancer. We developed a biocompatible, cationic polylactide (CPLA) nanocarrier to complex with and efficiently deliver IL‐8 small interfering RNA (siRNA) to CaP cells in vitro and in vivo. CPLA IL‐8 siRNA nanocomplexes (nanoplexes) protect siRNA from rapid degradation, are non‐toxic, have a prolonged lifetime in circulation, and their net positive charge facilitates penetration of cell membranes and subsequent intracellular trafficking. Administration of CPLA IL‐8 siRNA nanoplexes to immunodeficient mice bearing human CaP tumours produced significant antitumour activities with no adverse effects. Systemic (intravenous) or local intra‐tumour administration of IL‐8 siRNA nanoplexes resulted in significant inhibition of CaP growth. Magnetic resonance imaging and ultrasonography of experimental animals demonstrated reduction of tumour perfusion in vivo following nanoplex treatment. Staining of tumour sections for CD31 confirmed significant damage to tumour neovasculature after nanoplex therapy. These studies demonstrate the efficacy of IL‐8 siRNA nanotherapy for advanced, treatment‐resistant human CaP.     

Simultaneous blockade of programmed death 1 and vascular endothelial growth factor receptor 2 (VEGFR2) induces synergistic anti‐tumour effect in vivo

Recent basic and clinical studies have shown that the programmed death ligand (PD‐L)/PD‐1 pathway has a significant role in tumour immunity, and its blockade has a therapeutic potential against several human cancers. We hypothesized that anti‐angiogeneic treatment might augment the efficacy of PD‐1 blockade. To this end, we evaluated combining the blockade of PD‐1 and vascular endothelial growth factor receptor 2 ( VEGFR2) in a murine cancer model using Colon‐26 adenocarcinoma. Interestingly, simultaneous treatment with anti‐PD‐1 and anti‐VEGFR2 monoclonal antibodies (mAbs) inhibited tumour growth synergistically in vivo without overt toxicity. Blocking VEGFR2 inhibited tumour neovascularization significantly, as demonstrated by the reduced number of microvessels, while PD‐1 blockade had no impact on tumour angiogenesis. PD‐1 blockade might promote T cell infiltration into tumours and significantly enhanced local immune activation, as shown by the up‐regulation of several proinflammatory cytokine expressions. Importantly, VEGFR2 blockade did not interfere with T cell infiltration and immunological activation induced by PD‐1 blockade. In conclusion, simultaneous blockade of PD‐1 and VEGFR2 induced a synergistic in‐vivo anti‐tumour effect, possibly through different mechanisms that might not be mutually exclusive. This unique therapeutic strategy may hold significant promise for future clinical application.     

NF‐κB‐inducing kinase is a key regulator of inflammation‐induced and tumour‐associated angiogenesis

Angiogenesis is essential during development and in pathological conditions such as chronic inflammation and cancer progression. Inhibition of angiogenesis by targeting vascular endothelial growth factor (VEGF) blocks disease progression, but most patients eventually develop resistance which may result from compensatory signalling pathways. In endothelial cells (ECs), expression of the pro‐angiogenic chemokine CXCL12 is regulated by non‐canonical nuclear factor (NF)‐κB signalling. Here, we report that NF‐κB‐inducing kinase (NIK) and subsequent non‐canonical NF‐κB signalling regulate both inflammation‐induced and tumour‐associated angiogenesis. NIK is highly expressed in endothelial cells (ECs) in tumour tissues and inflamed rheumatoid arthritis synovial tissue. Furthermore, non‐canonical NF‐κB signalling in human microvascular ECs significantly enhanced vascular tube formation, which was completely blocked by siRNA targeting NIK. Interestingly, Nik^?/? mice exhibited normal angiogenesis during development and unaltered TNFα‐ or VEGF‐induced angiogenic responses, whereas angiogenesis induced by non‐canonical NF‐κB stimuli was significantly reduced. In addition, angiogenesis in experimental arthritis and a murine tumour model was severely impaired in these mice. These studies provide evidence for a role of non‐canonical NF‐κB signalling in pathological angiogenesis, and identify NIK as a potential therapeutic target in chronic inflammatory diseases and tumour neoangiogenesis. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

pDCs efficiently process synthetic long peptides to induce functional virus‐ and tumour‐specific T‐cell responses

Robust cell‐mediated immunity is required for immune control of tumours and protection from viral infections, with both CD4⁺ and CD8⁺ T cells playing a pivotal role. Synthetic long peptides (SLPs) represent an attractive way to induce such combined responses, as they contain both class I and class II epitopes. The ability of plasmacytoid dendritic cells (pDCs) to cross‐present SLPs has not yet been investigated; yet, pDCs play a critical role in shaping immune responses and have emerged as novel vectors for immunotherapy. Using overlapping 15‐mer peptide pools covering the entire sequence of CMVpp65 and MelA, representing a viral disease (cytomegalovirus, CMV) and a tumour (melanoma), respectively, we showed that human pDCs can effectively process SLPs. Our results demonstrated that pDCs potently cross‐present virus‐ and tumour‐derived SLPs and cross‐prime broad‐ranging, effective and long‐lived CD4⁺ and CD8⁺ T‐cell responses, triggering more efficient immune responses than short peptide loaded pDCs. This ability required intracellular processing by the proteasome and was enhanced by co‐exposure to TLR7/9‐L. Combining SLPs with pDCs represents a powerful immunotherapeutic strategy to elicit potent immune responses, which are required for clinical success in cancers and viral infections.     

Specific activation of CD4–CD8– double‐negative T cells by Trypanosoma cruzi‐derived glycolipids induces a proinflammatory profile associated with cardiomyopathy in Chagas patients

Cardiomyopathy is the most severe outcome of Chagas disease, causing more than 12 000 deaths/year. Immune cells participate in cardiomyopathy development either by direct tissue destruction, or by driving inflammation. We have shown that CD4^–CD8^– [double‐negative (DN)] T cells are major sources of inflammatory and anti‐inflammatory cytokines, associated with the cardiac (CARD) and indeterminate (IND) forms of Chagas disease, respectively. Here, we sought to identify Trypanosoma cruzi‐derived components that lead to activation of DN T cells in Chagas patients. Glycolipid (GCL), lipid (LIP) and protein‐enriched (PRO) fractions derived from trypomastigote forms of T. cruzi were utilized to stimulate cells from IND and CARD patients to determine DN T cell activation by evaluating CD69 and cytokine expression. We observed that GCL, but not LIP or PRO fractions, induced higher activation of DN T cells, especially T cell receptor (TCR)‐γδ DN T, from IND and CARD. GCL led to an increase in tumour necrosis factor (TNF) and interleukin (IL)‐10 expression by TCR‐γδ DN T cells from IND, while inducing IFN‐γ expression by TCR‐γδ DN T cells from CARD. This led to an increase in the ratio IFN‐γ/IL‐10 in TCR‐γδ DN T cells from CARD, favouring an inflammatory profile. These results identify GCL as the major T. cruzi component responsible for activation of DN T cells in chronic Chagas disease, associated predominantly with an inflammatory profile in CARD, but not IND. These findings may have implications for designing new strategies of control or prevention of Chagas disease cardiomyopathy by modulating the response to GCL.     

Anti‐PR3 immune responses induce segmental and necrotizing glomerulonephritis

Wegener's granulomatosis (WG) is a life‐threatening autoimmune vasculitis that affects lungs, kidneys and other organs. A hallmark of WG is the presence of classic anti‐neutrophil cytoplasmic antibodies (c‐ANCA) against self‐proteinase 3 (PR3). Little is known about the role of these antibodies and PR3‐specific immune responses in disease development. In this study, we demonstrate that PR3‐specific autoimmune responses are pathogenic in non‐obese diabetic (NOD) mice with an impaired regulatory arm of the immune response. Immunization of autoimmunity prone NOD mice with rmPR3 (recombinant mouse PR3) in complete Freund's adjuvant (CFA) resulted in high levels of c‐ANCA, without detectable disease development. However, when splenocytes from these immunized mice were transferred into immunodeficient NOD–severe combined immunodeficiency (SCID) mice, the recipient mice developed vasculitis and severe segmental and necrotizing glomerulonephritis. No disease developed in NOD–SCID mice that received splenocytes from the CFA‐alone‐immunized donors (controls), indicating that disease development depends upon PR3‐specific immune responses. In contrast to the pathology observed in NOD–SCID mice, no disease was observed when splenocytes from rmPR3‐immunized C57BL/6 mice were transferred into immunodeficient C57BL/6‐RAG‐1^–/– mice, suggesting that complex and probably multi‐genetic factors play a role in the regulation of disease development.     

HOPX is methylated and exerts tumour‐suppressive function through Ras‐induced senescence in human lung cancer

HOPX acts as a tumour suppressor in various cancers. However, the regulation of HOPX in human lung cancer as well as the mechanism underlying its tumour‐suppressive function has not yet been well elucidated. Here we investigated the epigenetic regulation and molecular mechanism by which HOPX exerts growth inhibitory effects. We found that HOPX was down‐regulated in 12 out of 13 lung cancer cell lines and in 69 out of 120 primary lung tumours at mRNA and protein levels. Patients with lung adenocarcinoma (ADC) exhibited significantly more positive staining of HOPX protein compared with lung squamous cell carcinoma (SCC) (p =0.036). Again in ADC, patients with higher HOPX expression had a significantly longer disease‐free survival (p =0.001). Methylation analysis showed that down‐regulation of HOPX was associated with DNA methylation (p =0.011). To analyse the function of HOPX in lung cancer cells, stable transfection with an expression vector of HOPX was performed. It turned out that HOPX inhibited tumour cell proliferation rate, migration, and invasion, and, more interestingly, forced expression of HOPX enhanced cellular senescence via activation of oncogenic Ras and the downstream MAPK pathway, which in turn led to decreased MDM2 and increased p21. On the contrary, knockdown of HOPX by siRNA resulted in reduced Ras activity, inactivation of the MAPK pathway, and decreased p21 levels, accompanied by reduced cellular senescence. Additionally, the HOPX‐induced senescence pathway was also active in human bronchial epithelial cells. Taken together, our data suggest that down‐regulation of HOPX was related to DNA methylation and that HOPX exerts tumour‐suppressive activity by oncogenic Ras‐induced cellular senescence in lung cancer cells. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Monocyte‐derived dendritic cells from patients with severe forms of chromoblastomycosis induce CD4+ T cell activation in vitro

Environmental and predisposing genetic factors are known to play a crucial role in the development of systemic autoimmune diseases. With respect to the role of environmental factors, it is not known how and to what extent they contribute to the initiation and exacerbation of systemic autoimmunity. In the present study, I considered this issue and asked if environmental factors can induce autoimmunity in the absence of specific susceptible genes. The development of genetically controlled mercury‐ and silver‐induced B cell activation and anti‐nucleolar autoantibodies (ANolA) production in genetically heterozygous outbred Institute of Cancer Research (ICR), Naval Medical Research Institute (NMRI) and Black Swiss mouse stocks were analysed. Four weeks of treatment with both mercury and silver induced a strong B cell activation characterized by increased numbers of splenic antibody‐secreting cells of at least one or more immunoglobulin (Ig) isotype(s) in all treated stocks. The three stocks also exhibited a marked increase in the serum IgE levels in response to mercury, but not silver. More importantly, in response to mercury a large numbers of ICR (88%), NMRI (96%) and Black Swiss (100%) mice produced different levels of IgG1 and IgG2a ANolA (a characteristic which is linked strictly to the H‐2 genes). Similarly, but at lower magnitudes, treatment with silver also induced the production of IgG1 and IgG2a ANolA in 60% of ICR, 75% of NMRI and 100% of Black Swiss mice. Thus, the findings of this study suggest that long‐term exposure to certain environmental factors can activate the immune system to produce autoimmunity per se, without requiring specific susceptible genes.     

High expression of insulin receptor on tumour‐associated blood vessels in invasive bladder cancer predicts poor overall and progression‐free survival

Bladder cancer is a frequently recurring disease with a very poor prognosis once progressed to invasive stages, and tumour‐associated blood vessels play a crucial role in this process. In order to identify novel biomarkers associated with progression, we isolated blood vascular endothelial cells (BECs) from human invasive bladder cancers and matched normal bladder tissue, and found that tumour‐associated BECs greatly up‐regulated the expression of insulin receptor (INSR). High expression of INSR on BECs of invasive bladder cancers was significantly associated with shorter progression‐free and overall survival. Furthermore, increased expression of the INSR ligand IGF‐2 in invasive bladder cancers was associated with reduced overall survival. INSR may therefore represent a novel biomarker to predict cancer progression. Mechanistically, we observed pronounced hypoxia in human bladder cancer tissue, and found a positive correlation between the expression of the hypoxia marker gene GLUT1 and vascular INSR expression, indicating that hypoxia drives INSR expression in tumour‐associated blood vessels. In line with this, exposure of cultured BECs and human bladder cancer cell lines to hypoxia led to increased expression of INSR and IGF‐2, respectively, and IGF‐2 increased BEC migration through the activation of INSR in vitro. Taken together, we identified vascular INSR expression as a potential biomarker for progression in bladder cancer. Furthermore, our data suggest that IGF‐2/INSR mediated paracrine crosstalk between bladder cancer cells and endothelial cells is functionally involved in tumour angiogenesis and may thus represent a new therapeutic target. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Nasal administration of interleukin‐33 induces airways angiogenesis and expression of multiple angiogenic factors in a murine asthma surrogate

The T‐helper cell type 2‐promoting cytokine interleukin‐33 (IL‐33) has been implicated in asthma pathogenesis. Angiogenesis is a feature of airways remodelling in asthma. We hypothesized that IL‐33 induces airways angiogenesis and expression of angiogenic factors in an established murine surrogate of asthma. In the present study, BALB/c mice were subjected to serial intranasal challenge with IL‐33 alone for up to 70 days. In parallel, ovalbumin (OVA) ‐sensitized mice were subjected to serial intranasal challenge with OVA or normal saline to serve as positive and negative controls, respectively. Immunohistochemical analysis of expression of von Willebrand factor and erythroblast transformation‐specific‐related gene, both blood vessel markers, and angiogenic factors angiogenin, insulin‐like growth factor‐1, endothelin‐1, epidermal growth factor and amphiregulin was performed in lung sections ex vivo. An established in‐house assay was used to test whether IL‐33 was able to induce microvessel formation by human vascular endothelial cells. Results showed that serial intranasal challenge of mice with IL‐33 or OVA resulted in proliferation of peribronchial von Willebrand factor‐positive blood vessels to a degree closely related to the total expression of the angiogenic factors amphiregulin, angiogenin, endothelin‐1, epidermal growth factor and insulin‐like growth factor‐1. IL‐33 also induced microvessel formation by human endothelial cells in a concentration‐dependent fashion in vitro. Our data are consistent with the hypothesis that IL‐33 has the capacity to induce angiogenesis at least partly by increasing local expression of multiple angiogenic factors in an allergen‐independent murine asthma surrogate, and consequently that IL‐33 or its receptor is a potential novel molecular target for asthma therapy.     

Hypoxia augments cytokine (transforming growth factor-beta (TGF-β) and IL-1)-induced vascular endothelial growth factor secretion by human synovial fibroblasts

Vascular endothelial growth factor (VEGF) is abundant in synovium and synovial fluids, where it probably contributes to vascular permeability and angiogenesis in arthritic joints. To investigate the probable sources of VEGF in synovium, we compared the ability of several cytokines (TGF-β, platelet-derived growth factor (PDGF), IL-1, tumour necrosis factor (TNF), basic fibroblast growth factor (bFGF) that are associated with arthritis and angiogenesis, to stimulate secretion of VEGF protein by human synovial fibroblasts. TGF-β was the strongest inducer of VEGF secretion; six times more VEGF was secreted when cells were stimulated by TGF-β than when stimulated by PDGF or IL-1 for 24 h. TNF-α and bFGF did not stimulate any secretion of VEGF. The stimulatory effects of TGF-β and IL-1 on VEGF secretion were additive. Hypoxic culture alone also stimulated VEGF secretion, but more importantly, hypoxic culture conditions doubled the rate of VEGF secretion stimulated by the cytokines TGF-β and IL-1. When dermal and synovial fibroblasts were stimulated identically by hypoxia and cytokines (TGF-β and IL-1), synovial fibroblasts secreted four times more VEGF than did dermal fibroblasts. Thus in rheumatoid arthritis, the capacity of synovial fibroblasts in the hypoxic environment to secrete large amounts of VEGF in response to cytokines such as TGF-β probably contributes significantly to angiogenesis in the synovium.