Multiplexing Angiogenic Receptor Quantification via Quantum Dots.

Clinical and biomedical research seeks single-cell quantification to better understand their roles in a complex, multicell environment. Recently, quantification of vascular endothelial growth factor receptors (VEGFRs) provided important insights into endothelial cell characteristics and response in tumor microenvironments. However, existing technologies for quantifying plasma membrane receptor tyrosine kinases (RTKs) lack multiplexing capabilities, limiting detailed characterization. Here, we use the unique spectral properties of quantum dots (Qdots) to optimize and dually quantify VEGFR1 and VEGFR2 on human umbilical vein endothelial cells (HUVECs). To enable this quantification, we reduce nonspecific binding between Qdot-conjugated antibodies and cells via buffer optimization. Second, we identify optimal labeling conditions by examining Qdot-conjugated antibody binding to five receptors: VEGFRs (VEGFR1 and VEGFR2), their coreceptor neuropilin1 (NRP1), and platelet-derived growth factor receptor (PDGFRα and PDGFRß). We establish that 800-20 000 is the dynamic range where accurate Qdot-enabled quantification can be achieved. Through these optimizations, we demonstrate measurement of 1 100 VEGFR1 and 6 900 VEGFR2 per HUVEC. We induce ∼90% upregulation of VEGFR1 and ∼30% downregulation of VEGFR2 concentration via 24 h VEGF-A165 treatment. We observe no change in VEGFR1 or VEGFR2 concentration with 24 h VEGF-B167 treatment. We further apply Qdots to analyze HUVEC heterogeneity and observe that 24 h VEGF-A165 treatment induces a ∼15% decrease in VEGFR2 heterogeneity, but little to no change in VEGFR1 heterogeneity. We observe that VEGF-B167 induces little to no change in either VEGFR1 or VEGFR2 heterogeneity. Overall, we demonstrate experimental and analytical strategies for quantifying two or more RTKs at single-level using Qdots, which will help provide new insights into biological systems.

Expansion of Islet-Resident Macrophages Leads to Inflammation Affecting ß Cell Proliferation and Function in Obesity.

The nature of obesity-associated islet inflammation and its impact on ß cell abnormalities remains poorly defined. Here, we explore immune cell components of islet inflammation and define their roles in regulating ß cell function and proliferation. Islet inflammation in obese mice is dominated by macrophages. We identify two islet-resident macrophage populations, characterized by their anatomical distributions, distinct phenotypes, and functional properties. Obesity induces the local expansion of resident intra-islet macrophages, independent of recruitment from circulating monocytes. Functionally, intra-islet macrophages impair ß cell function in a cell-cell contact-dependent manner. Increased engulfment of ß cell insulin secretory granules by intra-islet macrophages in obese mice may contribute to restricting insulin secretion. In contrast, both intra- and peri-islet macrophage populations from obese mice promote ß cell proliferation in a PDGFR signaling-dependent manner. Together, these data define distinct roles and mechanisms for islet macrophages in the regulation of islet ß cells.

New Molecular Targets of Anticancer Therapy - Current Status and Perspectives.

Molecularly targeted anticancer therapy involves the use of drugs or other substances affecting specific molecular targets that play a part in the development, progression and spread of a given neoplasm. By contrast, the majority of classical chemotherapeutics act on all rapidly proliferating cells, both healthy and cancerous ones. Target anticancer drugs are designed to achieve a particular aim and they usually act cytostatically, not cytotoxically like classical chemotherapeutics. At present, more than 300 biological molecular targets have been identified. The proteins involved in cellular metabolism include (among others) receptor proteins, signal transduction proteins, mRNA thread matrix synthesis proteins participating in neoplastic transformation, cell cycle control proteins, functional and structural proteins. The receptor proteins that are targeted by currently used anticancer drugs comprise the epithelial growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR) and vascular endothelial growth factor receptor(VEGFR). Target anticancer drugs may affect extracellular receptor domains (antibodies) or intracellular receptor domains (tyrosine kinase inhibitors). The blocking of the mRNA thread containing information about the structure of oncogenes (signal transduction proteins) is another molecular target of anticancer drugs. That type of treatment, referred to as antisense therapy, is in clinical trials. When the synthesis of genetic material is disturbed, in most cases the passage to the next cycle phase is blocked. The key proteins responsible for the blockage are cyclines and cycline- dependent kinases (CDK). Clinical trials are focused on natural and synthetic substances capable of blocking various CDKs. The paper discusses the molecular targets and chemical structure of target anticancer drugs that have been approved for and currently applied in antineoplastic therapy together with indications and contraindications for their application.

Induction of Scleroderma Fibrosis in Skin-Humanized Mice by Administration of Anti-Platelet-Derived Growth Factor Receptor Agonistic Autoantibodies.

OBJECTIVE: To describe a skin-SCID mouse chimeric model of systemic sclerosis (SSc; scleroderma) fibrosis based on engraftment of ex vivo-bioengineered skin using skin cells derived either from scleroderma patients or from healthy donors. METHODS: Three-dimensional bioengineered skin containing human keratinocytes and fibroblasts isolated from skin biopsy specimens from healthy donors or SSc patients was generated ex vivo and then grafted onto the backs of SCID mice. The features of the skin grafts were analyzed by immunohistochemistry, and the functional profile of the graft fibroblasts was defined before and after treatment with IgG from healthy controls or SSc patients. Two procedures were used to investigate the involvement of platelet-derived growth factor receptor (PDGFR): 1) nilotinib, a tyrosine kinase inhibitor, was administered to mice before injection of IgG from SSc patient sera (SSc IgG) into the grafts, and 2) human anti-PDGFR monoclonal antibodies were injected into the grafts. RESULTS: Depending on the type of bioengineered skin grafted, the regenerated human skin exhibited either the typical scleroderma phenotype or the healthy human skin architecture. Treatment of animals carrying healthy donor skin grafts with SSc IgG resulted in the appearance of a bona fide scleroderma phenotype, as confirmed by increased collagen deposition and fibroblast activation markers. Results of the experiments involving administration of nilotinib or monoclonal antibodies confirmed the involvement of PDGFR. CONCLUSION: Our results provide the first in vivo demonstration of the fibrotic properties of anti-PDGFR agonistic antibodies. This bioengineered skin-humanized mouse model can be used to test in vivo the progression of the disease and to monitor response to antifibrotic drugs.

Reduced type I collagen gene expression by skin fibroblasts of patients with systemic sclerosis after one treatment course with rituximab.

OBJECTIVES: There is evidence that B lymphocytes play a role in the pathogenesis of systemic sclerosis (scleroderma). Stimulatory autoantibodies targeting and activating normal human fibroblasts in vitro have been demonstrated in sera from scleroderma patients. Rituximab is a monoclonal antibody which selectively targets and depletes CD20+ B lymphocytes. We investigated the biological effects of rituximab in six patients affected by scleroderma with severe skin involvement. METHODS: Six patients with severe skin fibrosis, unresponsive to immunosuppressive treatment, were treated with 375 mg/m2 per week of intravenous rituximab for a total of four doses. Serum stimulatory autoantibodies to the PDGF receptor were detected. Fibroblast activation was evaluated in fibroblasts grown from skin biopsies performed at baseline and at months 3 and 6 post-treatment. The modified Rodnan's skin score, health assessment questionnaire (HAQ) and visual analogic scale (VAS) for global wellness and B lymphocyte count were performed monthly. RESULTS: A significant reduction of anti-PDGF receptor autoantibodies was observed in the serum of all patients 3 months after treatment. Fibroblasts showed a significant downregulation of type I collagen gene expression and of the intracellular signalling triggered by anti-PDGFR autoantibodies. A decrease of the skin score and an improvement of disability indexes matched with the in vitro results. A single course of rituximab reduced scleroderma fibroblast activation in vitro and the serum levels of anti-PDGFR stimulatory autoantibodies. CONCLUSIONS: These data provide further evidence of B-cell involvement in the pathogenesis of scleroderma. Targeting B cells may be a promising treatment for scleroderma patients, and controlled clinical trials are warranted.

Interpretation of an Extended Autoantibody Profile in a Well-Characterized Australian Systemic Sclerosis (Scleroderma) Cohort Using Principal Components Analysis.

OBJECTIVE: To determine the relationships between systemic sclerosis (SSc)-related autoantibodies, as well as their clinical associations, in a well-characterized Australian patient cohort. METHODS: Serum from 505 Australian SSc patients were analyzed with a commercial line immunoassay (EuroLine; Euroimmun) for autoantibodies to centromere proteins CENP-A and CENP-B, RNA polymerase III (RNAP III; epitopes 11 and 155), the 90-kd nucleolar protein NOR-90, fibrillarin, Th/To, PM/Scl-75, PM/Scl-100, Ku, topoisomerase I (topo I), tripartite motif-containing protein 21/Ro 52, and platelet-derived growth factor receptor. Patient subgroups were identified by hierarchical clustering of the first 2 dimensions of a principal components analysis of quantitative autoantibody scores. Results were compared with detailed clinical data. RESULTS: A total of 449 of the 505 patients were positive for at least 1 autoantibody by immunoblotting. Heatmap visualization of autoantibody scores, along with principal components analysis clustering, demonstrated strong, mutually exclusive relationships between CENP, RNAP III, and topo I. Five patient clusters were identified: CENP, RNAP III strong, RNAP III weak, topo I, and other. Clinical features associated with CENP, RNAP III, and topo I were consistent with previously published reports concerning limited cutaneous and diffuse cutaneous SSc. A novel finding was the statistical separation of RNAP III into 2 clusters. Patients in the RNAP III strong cluster had an increased risk of gastric antral vascular ectasia, but a lower risk of esophageal dysmotility. Patients in the other cluster were more likely to be male and to have a history of smoking and a history of malignancy, but were less likely to have telangiectasia, Raynaud's phenomenon, and joint contractures. CONCLUSION: Five major autoantibody clusters with specific clinical and serologic associations were identified in Australian SSc patients. Subclassification and disease stratification using autoantibodies may have clinical utility, particularly in early disease.

Functional autoantibodies in systemic sclerosis pathogenesis.

Circulating antinuclear autoantibodies contribute to the diagnosis of systemic sclerosis (SSc) and correlate with disease-specific organ manifestations. Recent findings show the induction of interstitial lung disease and obliterative vasculopathy by transfer of IgG from SSc patients in healthy mice indicating a contribution of antibodies to SSc pathogenesis. Several functional or agonistic autoantibodies have been described in SSc, thus putting autoimmunity into a new spotlight. Autoantibodies against the angiotensin II receptor type-1 and the endothelin1 receptor type-A are associated with severe disease and provide new insights into its pathogenesis. They link the hallmarks of SSc, vasculopathy, immune activation, and fibrosis. At present, the contribution of the specific antibodies to disease manifestations remains to be examined. However; functional autoantibodies could represent a significant piece in the puzzle of SSc pathogenesis and may open new gateways and opportunities for therapeutic intervention. This review focuses on the features of functional autoantibodies in SSc.

Lack of association of platelet-derived growth factor (PDGF) receptor autoantibodies and severity of chronic graft-versus-host disease (GvHD).

PURPOSE: The existence of platelet-derived growth factor (PDGF) receptor autoantibodies in systemic sclerosis is conflicting, and such antibodies were also detected in patients with chronic graft-versus-host disease (GvHD) after allogeneic peripheral blood stem cell transplantation (PBSCT). We therefore aimed to screen for PDGF receptor autoantibodies in patients with chronic GvHD. PATIENTS AND METHODS: We evaluated the existence of PDGF receptor autoantibodies in 39 patients, while 17 patients presented with a limited and 8 patients with an extensive chronic GvHD, respectively. Furthermore, 14 out of 39 patients had no chronic GvHD. RESULTS: We detected at least low levels of PDGF receptor autoantibodies in nearly all (35 of 39) patients after allogeneic PBSCT. Interestingly, only one of six patients with high levels of PDGF receptor autoantibodies presented with an extensive chronic GvHD, while the remaining six patients had no clinical signs of chronic GvHD. Thus, there was no correlation between the quantitative detection of antibodies directed against the PDGF receptor and the presence or severity of chronic GvHD. CONCLUSION: Platelet-derived growth factor receptor autoantibodies could easily be detected in patient sera. Nevertheless, we did not observe any correlation between the presence of PDGF receptor autoantibodies and the severity of chronic GvHD in patients who underwent allogeneic PBSCT.

Consequence of dose scheduling of sunitinib on host immune response elements and vaccine combination therapy.

Our study investigated the immunomodulatory effects of sunitinib to rationally design combinational platforms with immunotherapies for the treatment of solid tumors. Using a mouse model, we studied the effects of sunitinib given for 4 weeks at concentrations comparable to 37.5-50 mg/day in humans, followed by 2 weeks off the drug (sunitinib 4/2). We assessed the effect of differently timed combinations of sunitinib and a poxvirus-based vaccine encoding carcinoembryonic antigen (CEA) plus 3 costimulatory molecules on immune responses in CEA-transgenic (CEA-Tg) mice. Antitumor studies were performed in CEA-Tg mice bearing CEA-transfected MC38 murine colon carcinomas (MC38-CEA), treated either concurrently or sequentially with sunitinib and vaccine. In vitro, sunitinib inhibited PDGFR phosphorylation on MC38-CEA cells at concentrations similar to those biologically available during human treatment. In vivo, one cycle of sunitinib 4/2 caused bimodal immune effects: (a) decreased regulatory cells during the 4 weeks of treatment and (b) an immune-suppression rebound during the 2 weeks of treatment interruption. In a model using CEA-Tg mice bearing CEA(+) tumors, continuous sunitinib followed by vaccine increased intratumoral infiltration of antigen-specific T lymphocytes, decreased immunosuppressant T regulatory cells and myeloid-derived suppressor cells, reduced tumor volumes and increased survival. The immunomodulatory activity of continuous sunitinib administration can create a more immune-permissive environment. In combination with immunotherapies, sunitinib treatment should precede vaccine, to precondition the immune system, to maximize the response to vaccine-mediated immune enhancement.

Rationale for the development of IMC-3G3, a fully human immunoglobulin G subclass 1 monoclonal antibody targeting the platelet-derived growth factor receptor alpha.

A large body of evidence suggests that the platelet-derived growth factor (PDGF) family and associated receptors are potential targets in oncology therapeutic development because of their critical roles in the proliferation and survival of various cancers and in the regulation and growth of the tumor stroma and blood vessels. Several small molecules that nonspecifically target the PDGF signaling axis are in current use or development as anticancer therapies. However, for the majority of these agents, PDGF and its receptors are neither the primary targets nor the principal mediators of anticancer activity. IMC-3G3, a fully human monoclonal antibody of the immunoglobulin G subclass 1, specifically binds to the human PDGF receptor alpha (PDGFRalpha) with high affinity and blocks PDGF ligand binding and PDGFRalpha activation. The results of preclinical studies and the frequent expression of PDGFRalpha in many types of cancer and in cancer-associated stroma support a rationale for the clinical development of IMC-3G3. Currently, IMC-3G3 is being evaluated in early clinical development for patients with several types of solid malignancies.

Oxidative stress and the pathogenesis of scleroderma: the Murrell's hypothesis revisited.

Systemic sclerosis (SSc, scleroderma) is a devastating, immune-mediated, multisystem disorder characterized by microvasculature damage, circulating autoantibodies, and fibroblast activation, leading to massive fibrosis of skin, vessels, muscles, and visceral organs. Scleroderma causes disability and death as the result of end-stage organ failure. At present, no specific diagnostic nor therapeutic tools are available to handle the disease. In spite of significant effort, the etiology and pathogenesis of SSc remain obscure and, consequently, the disease outcome is unpredictable. Several years ago, Murrell suggested a unifying hypothesis linking the pathogenesis of scleroderma to the generation of a large excess of reactive oxygen species. This hypothesis has been substantiated by several reports indicating the presence of an abnormal redox state in patients with scleroderma. This review will summarize the available evidence supporting the link between free radicals and the main pathological features of scleroderma.

Autoantibodies in systemic sclerosis (scleroderma): clues for clinical evaluation, prognosis and pathogenesis.

Systemic sclerosis is a generalized autoimmune connective tissue disease of unknown aetiology. Profound vascular and immunological dysregulations result in tissue fibrosis affecting the skin and internal organs. Currently, two main clinical subtypes are distinguished, i.e. limited and diffuse cutaneous systemic sclerosis, which differ significantly in the clinical course and prognosis. Autoantibodies against topoisomerase (Scl-70), centromere-associated proteins, and nucleolar antigens are important for the diagnosis of the disease and give clues for its clinical manifestations and prognosis (prognostic autoantibodies). For most of these antibodies, however, the role in pathogenesis is not established. Anti-centromere antibodies are associated with limited cutaneous involvement and risk for pulmonary hypertension, whereas anti-topoisomerase I is associated with diffuse progressive disease and severe interstitial lung disease. Anti-Th/To positivity is associated with limited skin involvement but a high risk for severe internal organ involvement (Kidneys, PAH, Lung fibrosis). Anti-RNA polymerase I/III antibodies are associated with a high risk for renal involvement. Autoantibodies against the PDGF receptor and fibrillin-1 seem to play important roles in the pathogenetic process of systemic sclerosis.

Pathogenic autoantibodies in systemic sclerosis.

Systemic sclerosis, scleroderma, is a disease characterized by widespread vascular injury and fibrosis of the skin and visceral organs. Circulating autoantibodies against several intracellular antigens are common in scleroderma patients. The specificities of such autoantibodies correlate with distinct clinical manifestations. However, till date there is no evidence that these autoantibodies, though helpful in diagnosis and prognosis, are linked to the pathogenesis of scleroderma nor that they may cause any feature of the disease. Recently, the discovery of novel agonistic autoantibodies targeting the PDGF receptor has provided important insight into the molecular pathogenesis of scleroderma and the intracellular mechanisms leading to fibrosis. Although their pathogenic role awaits validation in in vivo models, these antibodies represent the molecular link between the immune system and fibrosis.

Stimulatory autoantibodies to the PDGF receptor: a link to fibrosis in scleroderma and a pathway for novel therapeutic targets.

Systemic sclerosis (scleroderma) is a complex disease characterized by excessive deposition of collagen and abnormalities of blood vessels. In addition, activation of the immune system is a central feature of scleroderma as shown by mononuclear cell infiltration of the skin, autoantibody production and release of inflammatory cytokines. The pathogenesis of the disease is poorly understood and the molecular events underlying the main clinical features are not known. The detection of agonistic autoantibodies targeting PDGF receptor in serum of patients with scleroderma may indicate a novel link between phenotypic features of the disease and a specific signalling pathway. Agonistic PDGF receptor antibodies induce in vitro the scleroderma phenotype in normal human fibroblasts and, thus, link autoimmunity to fibrosis. These findings pave the way to novel therapeutic strategies.

[The preparation and identification on monoclonal antibody to platelet-derived growth factor receptor].

OBJECTIVE: Through genetic engineering to produce the fusion protein of glutathione S-transferase (GST) linked to amino-terminal end of platelet-derived growth factor receptor (PDGFR), and to prepare the bioactive monoclonal antibody. METHODS: With taking GST-PDGFR-N fusion protein as immunogen, the anti-PDGFR monoclonal antibody was produced by using the hybridoma technique, of which then the antigen binding characteristic was identified by indirect enzyme-linked immunosorbent assay (ELISA), Western blot and immunohistochemistry methods. RESULTS: Two cell strains of hybridoma were obtained and named as 3B12F5 and 3C6H7C11 which secreted the anti-PDGFR monoclonal antibody, of which the class and subtype identification demonstrated both strains to produce all type of IgG1. The indirect ELISA result showed that the titers of ascites fluid which two hybridoma induced were 1 : 102400 and 1 : 25600. Western blot demonstrated that the two antibodies could recognize specifically the immunogen on PDGFR and U251 cell line. The cell immunohistochemistry proved that the antibody could recognize the expressed PDGFR antigens of neurogliocytoma U251 and bladder carcinoma BIU87 cell lines. CONCLUSION: We prepare successfully the PDGFR monoclonal antibody and provide a useful tool for researching on the PDGFR expression and clinical detection.

Stimulatory autoantibodies to PDGF receptor in patients with extensive chronic graft-versus-host disease.

Extensive chronic graft-versus-host disease (ecGVHD) is characterized by fibrosis similar to that of patients with systemic sclerosis (scleroderma). Since stimulatory autoantibodies against the platelet-derived growth factor (PDGF) receptor (PDGFR) have been found in patients with scleroderma and are responsible for the activation of skin fibroblasts, we tested the hypothesis that these autoantibodies are also present in patients affected by ecGVHD. Serum from 39 patients subjected to allogeneic stem cell transplantation for hematologic malignancies (22 with ecGVHD and 17 without cGVHD) and 20 healthy controls was assayed for the presence of stimulatory autoantibodies to the PDGFR by incubating purified IgG with mouse-embryo fibroblasts lacking PDGFR alpha or beta chains or with the same cells expressing PDGFR alpha. Stimulatory antibodies to the PDGFR were found selectively in all patients with ecGVHD but in none of the patients without cGVHD. Higher levels were detected in patients with generalized skin involvement and/or lung fibrosis. Antibodies recognized native PDGFR, induced tyrosine phosphorylation, accumulation of reactive oxygen species (ROS), and stimulated type 1 collagen gene expression through the Ha-Ras-ERK1/2-ROS signaling pathway. The biologic activity of these autoantibodies suggests a role in the development of fibrosis and argues for a common pathogenetic trait in ecGVDH and scleroderma phenotypes.