369 PENTRAXIN 3 AS A DIAGNOSTIC AND PROGNOSTIC MARKER OF ACTIVE MYOCARDITIS

Background

Pentraxin 3 (PTX3) is an acute phase protein, which regulates the outcomes of inflammation. Currently, there are no myocarditis-typical biomarkers that allow a non-invasive diagnosis, and endomyocardial biopsy (EMB) is still the gold standard. Finally, risk stratification is often challenging in these patients.

Aim

To investigate whether PTX3 could be expressed in cardiomyocytes and released during myocarditis, serving as a novel and independent diagnostic indicator of myocardial inflammation, and contributing to prognosis prediction.

Methods

Fifty-five patients with a diagnosis of acute or chronic active myocarditis proven by cardiac magnetic resonance (CMR) and/or endomyocardial biopsy (EMB), were included. First, we evaluated tissue PTX3 expression by immunohistochemistry (IHC). Then, we assessed circulating blood PTX3 by ELISA technique.

Results

On cardiac tissue, PTX3 at IHC did not localize in the interstitium, and showed an inconstant expression in the vascular endothelium, but a marked staining by cardiomyocytes in all myocarditis patients. The only exception was represented by two patients with systemic COVID-19, with SARS-CoV-2 and PVB-19 intracardiac genomes, respectively, who showed a diffuse cardiac PTX3 expression. Remarkably, at semi-quantitative pixel analysis, viral aetiology showed higher levels of tissue expression, rather than the autoimmune one. Circulating PTX3 levels were significantly higher in myocarditis patients than controls, with pathologic values in 87% of myocarditis patients, and none among controls. Remarkably, plasma PTX3 proved to be more sensitive in myocarditis detection than CRP, ESR, troponin T, and NT-proBNP. As regards of prognosis, we observed that patients with heart failure (HF) presentation all had elevated PTX3 levels, as compared with chest pain or arrhythmia. Remarkably, patients with reduced LVEF (<50%) at admission who recovered during follow-up had higher baseline PTX3 levels, rather than those whose systolic function did not improve.

Conclusions

Tissue PTX3 is mostly expressed by cardiomyocytes in patients with active myocarditis on EMB samples. In addition, plasma PTX3 is a sensitive diagnostic and prognostic marker in patients with inflammatory cardiomyopathy.

PTX3 as a novel inflammatory biomarker in patients with myocarditis

Background

Pentraxin-3 (PTX3) is an acute phase protein, which plays pivotal roles in innate immunity and inflammation. Among cardiovascular diseases, PTX3 was found to be elevated in acute myocardial infarction, chronic heart failure, and cardiac arrest. So far, however, PTX3 has never been investigated in the context of myocarditis.

Purpose

To evaluate PTX3 as a circulating marker of inflammation in patients with suspected myocarditis.

Methods

We enrolled 30 consecutive inpatients with new diagnosis of myocarditis, proven both by the updated Lake Louise criteria on cardiac magnetic resonance (CMR), and by the Dallas criteria on endomyocardial biopsy (EMB) (100%). Circulating serum PTX3 was assessed at the time of EMB, by ELISA technique using a commercial kit. Normal values for PTX3 were considered as <2 ng/mL, as in previous studies. A normal control group (n=10) was used for results validation of PTX3.

Results

In our cohort (77% males, age 50±18 y; median left ventricle ejection fraction [LVEF] 50%, IQR 30–59%), PTX3 levels were assessed in 30 patients. PTX3 levels were elevated in 26/30 (87%) patients with myocarditis (median 4,36 ng/mL, IQR 2,44–6,72, range 1,20–40,0), and in none (0/10) among healthy controls (median 1,28 ng/mL, IQR 1,04–1,36, range 0,77–1,94) (p=0,001). In the study group, the yield of other cardiac biomarkers was lower: 12/30 (40%) for C-reactive protein, 23/30 (77%) for T-troponin, and 20/30 (67%) for NTproBNP. PTX3 was constantly elevated in patients presenting with heart failure (HF) (16/16, 100%), compared with those presenting with acute coronary syndrome-like (8/10, 80%), or arrhythmias (2/4, 50%) (p=0,024). In particular, elevated PTX3 was associated with systolic dysfunction (LVEF <50%) at discharge (16/16 vs. 10/14, p=0,022).

Conclusion

Our preliminary data suggest PTX3 as a novel biomarker with potential diagnostic and prognostic value for myocarditis and inflammatory cardiomyopathy.

Funding Acknowledgement

Type of funding sources: None.

Platelet Phagocytosis via P-selectin Glycoprotein Ligand 1 and Accumulation of Microparticles in Systemic Sclerosis

OBJECTIVE

It is unclear why activated platelets and platelet-derived microparticles (MPs) accumulate in the blood of patients with systemic sclerosis (SSc). This study was undertaken to investigate whether defective phagocytosis might contribute to MP accumulation in the blood of patients with SSc.

METHODS

Blood samples were obtained from a total of 81 subjects, including 25 patients with SSc and 26 patients with stable coronary artery disease (CAD). Thirty sex- and age-matched healthy volunteers served as controls. Studies were also conducted in NSG mice, in which the tail vein of the mice was injected with MPs, and samples of the lung parenchyma were obtained for analysis of the pulmonary microvasculature. Tissue samples from human subjects and from mice were assessed by flow cytometry and immunochemical analyses for determination of platelet-neutrophil interactions, phagocytosis, levels and distribution of P-selectin, P-selectin glycoprotein ligand 1 (PSGL-1), and HMGB1 on platelets and MPs, and concentration of byproducts of neutrophil extracellular trap (NET) generation/catabolism.

RESULTS

Activated P-selectin+ platelets and platelet-derived HMGB1+ MPs accumulated in the blood of SSc patients but not in the blood of healthy controls. Patients with CAD, a vasculopathy independent of systemic inflammation, had fewer P-selectin+ platelets and a negligible number of MPs. The expression of the receptor for P-selectin, PSGL-1, in neutrophils from SSc patients was significantly decreased, raising the possibility that phagocytes in SSc do not recognize activated platelets, leading to a failure of phagocytosis and continued neutrophil release of MPs. As evidence of this process, activated platelets were not detected in the neutrophils from SSc patients, whereas they were consistently present in the neutrophils from patients with CAD. HMGB1+ MPs elicited generation of NETs, which were only detected in the plasma of SSc patients. In mice, P-selectin-PSGL-1 interaction resulted in platelet phagocytosis in vitro and influenced the ability of MPs to elicit NETs, endothelial activation, and migration of leukocytes through the pulmonary microvasculature.

CONCLUSION

The clearance of activated platelets via PSGL-1 limits the undesirable effects of MP-elicited neutrophil activation. This balance is disrupted in patients with SSc. Its reconstitution might curb vascular inflammation and prevent fibrosis.

Begelomab for severe refractory dermatomyositis: A case report

RATIONALE

Severe refractory idiopathic inflammatory myopathy (IIM) represents a challenge for the clinician. The lack of efficacy of available tools reflects our incomplete insight into the molecular events sustaining the inflammatory tissue damage in these patients. We present the first case of refractory IIM treated with anti-dipeptidyl peptidase-4 (DPP-4)/cluster of differentiation 26 (CD26) monoclonal antibody.

PATIENT CONCERNS

A 55-year old man presented with proximal muscle weakness, diffuse erythematous skin lesions which rapidly evolved into ulcerations, dysphagia and dysphonia.

DIAGNOSIS

Increased serum creatine kinase levels and histological findings at muscle and skin biopsies were compatible with the diagnosis of dermatomyositis (DM). Several lines of treatment failed to control the disease including steroids, mycophenolate mofetil, tacrolimus, intravenous immunoglobulins and rituximab. Despite therapy, the patient also had recurrent intestinal vasculitis causing bowel perforation. Concurrently, DPP-4/CD26 expression in the patient's skin and skeletal muscle was observed.

INTERVENTIONS

The patient was treated with begelomab, a murine immunoglobulin G2b monoclonal antibody against DPP-4/CD26.

OUTCOMES

Dysphagia, skin lesions and intestinal vasculitis resolved and the patient experienced a significant improvement of his quality of life.

CONCLUSION

Blockade of DPP-4/CD26, which is expressed on T cells and mediates T cell activation and function, is safe and might be effective in patients with refractory DM.

Mer tyrosine kinase (MerTK) as a possible link between resolution of inflammation and tissue fibrosis in IgG4-related disease

OBJECTIVES

IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory disorder characterized by a dysregulated resolution of inflammation and wound healing response that might develop after an apoptotic insult induced by cytotoxic T lymphocytes (CTLs). Mer receptor tyrosine kinase (MerTK) and its ligand Protein S (ProS1) have a pivotal role in the resolution of inflammation, being implicated in the clearance of apoptotic cells, quenching of the immune response and development of tissue fibrosis. In the present work we aimed to investigate a possible involvement of the MerTK signalling pathway in the pathogenesis of IgG4-RD and development of tissue fibrosis.

METHODS

MerTK and ProS1 expression patterns in IgG4-RD lesions were evaluated by immunohistochemistry and immunofluorescence studies. Circulating MerTK+ monocytes, soluble Mer and MerTK ligands were measured in the peripheral blood of IgG4-RD patients and healthy controls by flow cytometry and ELISA, respectively.

RESULTS

MerTK was highly expressed by macrophages infiltrating IgG4-RD lesions. MerTK+ macrophages were more abundant in IgG4-RD than in Sjögren syndrome and interacted with apoptotic cells and ProS1 expressing T and B lymphocytes. Moreover, they expressed the pro-fibrotic cytokine TGF-β and their numbers declined following rituximab induced disease remission. Circulating MerTK+ monocytes, soluble Mer and MerTK ligands were not increased in the peripheral blood of patients with IgG4-RD.

CONCLUSIONS

The MerTK-ProS1 axis is activated in IgG4-RD lesions, possibly leading to persistent stimulation of processes involved in the resolution of inflammation and tissue fibrosis.

Pharmacological blockade of TNFα prevents sarcopenia and prolongs survival in aging mice

Sarcopenia is a hallmark of aging. Inflammation due to increased generation of cytokines such as TNFα, IL-1β and IL-6 has been implicated in the pathogenesis of sarcopenia. In skeletal muscle of C57BL/6 mice from 12 until 28 months of age, we observed a progressive reduction of myofiber cross sectional area, loss of type II fibers and infiltration by inflammatory cells. Muscle strength decreased in parallel. Pharmacological TNFα blockade by weekly subcutaneous injection of Etanercept from 16 to 28 months of age prevented atrophy and loss of type II fibers, with significant improvements in muscle function and mice lifespan. The effects on leukocyte recruitment were limited. These results provide a proof of principle that endogenous TNFα is sufficient to cause sarcopenia and to reduce animal survival, and open a novel perspective on novel potential pharmacological treatment strategies based on TNFα blockade to prevent the noxious events associated with aging.

Galectin-3 in Prostate Cancer Stem-Like Cells Is Immunosuppressive and Drives Early Metastasis

Galectin-3 (Gal-3) is an extracellular matrix glycan-binding protein with several immunosuppressive and pro-tumor functions. The role of Galectin-3 in cancer stem-like cells (CSCs) is poorly investigated. Here, we show that prostate CSCs also colonizing prostate-draining lymph nodes of transgenic adenocarcinoma of the mouse prostate (TRAMP) mice overexpress Gal-3. Gal-3 contributes to prostate CSC-mediated immune suppression because either Gal-3 silencing in CSCs, or co-culture of CSCs and T cells in the presence of the Gal-3 inhibitor N-Acetyl-D-lactosamine rescued T cell proliferation. N-Acetyl-D-lactosamine also rescued the proliferation of T cells in prostate-draining lymph nodes of TRAMP mice affected by prostate intraepithelial neoplasia. Additionally, Gal-3 impacted prostate CSC tumorigenic and metastatic potential in vivo, as Gal-3 silencing in prostate CSCs reduced both primary tumor growth and secondary invasion. Gal-3 was also found expressed in more differentiated prostate cancer cells, but with different intracellular distribution as compared to CSCs, which suggests different functions of Gal-3 in the two cell populations. In fact, the prevalent nuclear and cytoplasmic distribution of Gal-3 in prostate CSCs made them less susceptible to apoptosis, when compared to more differentiated prostate cancer cells, in which Gal-3 was predominantly intra-cytoplasmic. Finally, we found Gal-3 expressed in human and mouse prostate intraepithelial neoplasia lesions and in metastatic lymph nodes. All together, these findings identify Gal-3 as a key molecule and a potential therapeutic target already in the early phases of prostate cancer progression and metastasis.

B lymphocytes contribute to stromal reaction in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a prominent stromal reaction that has been variably implicated in both tumor growth and tumor suppression. B-lymphocytes have been recently implicated in PDAC progression but their contribution to the characteristic stromal desmoplasia has never been assessed before. In the present work, we aimed to verify whether B-lymphocytes contribute to stromal cell activation in PDAC. CD19⁺ B-lymphocytes purified from peripheral blood of patients with PDAC were cultivated in the presence of human pancreatic fibroblasts and cancer-associated fibroblasts. Released pro-fibrotic soluble factors and collagen production were assessed by ELISA and Luminex assays. Quantitative RT-PCR was used to assess fibroblast activation in the presence of B cells. The expression of selected pro-fibrotic and inflammatory molecules was confirmed on PDAC tissue sections by multi-color immunofluorescence studies. We herein demonstrate that B-cells from PDAC patients (i) produce the pro-fibrotic molecule PDGF-B and stimulate collagen production by fibroblasts; (ii) express enzymes implicated in extracellular matrix remodeling including LOXL2; and (iii) produce the chemotactic factors CCL-4, CCL-5, and CCL-11. In addition we demonstrate that circulating plasmablasts are expanded in the peripheral blood of patients with PDAC, stimulate collagen production by fibroblasts, and infiltrate pancreatic lesions. Our results indicate that PDAC is characterized by perturbations of the B-cell compartment with expansion of B-lymphocyte subsets that directly contribute to the stromal reaction observed at disease site. These findings provide an additional rationale for modulating B-cell activity in patients with pancreatic cancer.

AB0154 MERTK AND THE RESOLUTION OF INFLAMMATION IN IGG4-RELATED DISEASE

Background:

IgG4-Related Disease (IgG4-RD) is characterized by fibrotic lesions, serum IgG4 elevation, and prompt response to glucocorticoids. B and T lymphocytes are considered the initiators of tissue inflammation in IgG4-RD, but the prominent stromal reaction observed at disease sites suggest that a dysregulation of processes involved in the resolution of inflammation could be pathologically relevant as well. Mer receptor tyrosine kinase (MerTK) and its ligands protein S (Pros1) have a pivotal role in the resolution of inflammation through the activation of a well-characterized signaling pathway that ultimately dampens the immune response and promotes the recovery of tissue function. MerTK and the processes involved in the resolution of inflammation have never been addressed in IgG4-RD.

Objectives:

To investigate MerTK involvement in the pathogenesis of IgG4-RD by evaluating (a) the expression of MerTK and of its endogenous ligands in IgG4-RD tissues; (b) the presence of circulating precursors of MerTK+ cells infiltrating IgG4-RD lesions in the peripheral blood of IgG4-RD patients; (c) the effects of immunosuppressive therapies on MerTK expression in IgG4-RD tissues.

Methods:

Three distinct cohorts of IgG4-RD patients were included in this study. 8 active patients were used for immunohistochemistry studies for MerTK expression. 16 IgG4-RD and 14 Sjögren syndrome patients, together with 6 control tonsils, were used for multicolor immunofluorescence studies and TissueQuest software quantification of the expression of MerTK, CD68, CD163, Pros1, Gas6, CD4, SLAMF7, CD19, IgG4, cleaved caspase-3. 10 untreated IgG4-RD patients were used to evaluate MerTK expression in circulating monocytes subsets and fibrocytes by flow cytometry.

Results:

MerTK was highly expressed in IgG4-RD affected organs. MerTK+ cells accounted on average for 16% (range 5-35%) of all cells in the tissue, and the majority of them expressed CD68,reflecting a monocyte-macrophage origin. 33.5 % (interquartile range (IQR) 26-41%) of MerTK+ cells co-expressed CD68 and CD163, while 30.5% (IQR 19-41.5%) expressed CD68 but not CD163. CD68+MerTK+ cells displayed two main morphological appearances, compatible with those of macrophages and of myofibroblasts. In addition, MerTK+ cell number was significantly increased in salivary glands from IgG4-RD patients compared to Sjögren syndrome (p < 0.0001). Circulating precursors of CD68+MerTK+ cells infiltrating IgG4-RD lesions were identified by flow cytometery in the peripheral blood of patients with active IgG4-RD as MerTK+ populations of intermediate monocytes, nonclassical monocytes and collagen expressing fibrocytes. MerTK ligand Pros1 was exposed on 52% (IQR 42-57%) of infiltrating B lymphocytes, 74% (IQR 54-89%) of infiltrating T lymphocytes, and, likely, on apoptotic cells that were detected in IgG4-RD tissues. CD68+MerTK+ cells were found in physical contact with Pros1+ cells in IgG4-RD lesions and their number decreased by 56% after successful treatment with rituximab.

Conclusion:

MerTK is abundant in IgG4-RD affected organs and is preferentially expressed on CD68+ macrophages and myofibroblasts that infiltrate IgG4-RD lesions. MerTK+ cells might interact with apoptotic cells and Pros1 expressing T and B lymphocytes in IgG4-RD tissues, leading to the persistent activation of processes involved in the resolution of inflammation and promoting the development of tissue fibrosis.

Disclosure of Interests:

None declared

Exacerbation of Murine Experimental Autoimmune Myositis by Toll-Like Receptor 7/8

OBJECTIVE

Toll-like receptor 7 (TLR-7), TLR-8, and interferon (IFN)-induced genes are expressed in patients with idiopathic inflammatory myositis. This study was undertaken to investigate whether their activation influences the natural history of the disease.

METHODS

Experimental autoimmune myositis was induced in mice by injection of the amino-terminal portion of the murine histidyl-transfer RNA synthetase (HisRS). Disease was compared in the presence or the absence of the TLR-7/8 agonist R-848 in wild-type mice and in mice that fail to express the IFNα/β receptor (IFNα/βR-null mice).

RESULTS

Experimental autoimmune myositis induced by a single intramuscular immunization with HisRS spontaneously abated after 7-8 weeks. In contrast, levels of anti-HisRS autoantibodies, endomysial/perimysial leukocyte infiltration, and myofiber regeneration persisted at the end of the follow-up period (22 weeks after immunization) in mice immunized with HisRS in the presence of R-848. Myofiber major histocompatibility complex (MHC) class I molecules were detectable only in mice immunized with both HisRS and R-848. MHC up-regulation occurred early and in muscles that were not directly injected with HisRS. Muscle MHC expression paralleled with leukocyte infiltration. MHC class I molecules were selectively up-regulated in myotubes challenged with R-848 in vitro. Type I IFN was necessary for the prolonged autoantibody response and for the spreading of the autoimmune response, as demonstrated using IFNα/βR-null mice. Muscle infiltration was maintained in the injected muscle up to the end of the follow-up period.

CONCLUSION

TLR-7/8 activation is necessary to induce and maintain a systemic autoimmune response targeting the skeletal muscle. This experimental autoimmune myositis model reproduces many characteristics of human idiopathic inflammatory myopathies and may represent a tool for preclinical studies.

Innate Immune Cells: Gatekeepers of Endometriotic Lesions Growth and Vascularization

Infiltration by inflammatory leukocytes is a hallmark of all forms of endometriosis. Conversely, the innate immune system plays a key role in regulating events such as cell adhesion, migration, survival and neoangiogenesis of transformed or ectopic tissue. All these features are involved, and possibly required, in the development of endometriotic lesions. Recent data suggest that infiltrating leukocytes are not a mere epiphenomenon but represent an actual requirement for the development of the disease. In this scenario, the functional plasticity of infiltrating macrophages is a key event in the origin and maintenance of endometriotic lesions: the erroneous polarization of macrophages towards cells sustaining angiogenesis and tissue remodeling represents a potential target for novel molecular therapies.

The peritoneum: healing, immunity, and diseases

The peritoneum defines a confined microenvironment, which is stable under normal conditions, but is exposed to the damaging effect of infections, surgical injuries, and other neoplastic and non-neoplastic events. Its response to damage includes the recruitment, proliferation, and activation of a variety of haematopoietic and stromal cells. In physiological conditions, effective responses to injuries are organized; inflammatory triggers are eliminated; inflammation quickly abates; and the normal tissue architecture is restored. However, if inflammatory triggers are not cleared, fibrosis or scarring occurs and impaired tissue function ultimately leads to organ failure. Autoimmune serositis is characterized by the persistence of self-antigens and a relapsing clinical pattern. Peritoneal carcinomatosis and endometriosis are characterized by the persistence of cancer cells or ectopic endometrial cells in the peritoneal cavity. Some of the molecular signals orchestrating the recruitment of inflammatory cells in the peritoneum have been identified in the last few years. Alternative activation of peritoneal macrophages was shown to guide angiogenesis and fibrosis, and could represent a novel target for molecular intervention. This review summarizes current knowledge of the alterations to the immune response in the peritoneal environment, highlighting the ambiguous role played by persistently activated reparative macrophages in the pathogenesis of common human diseases. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The clearance of cell remnants and the regeneration of the injured muscle depend on soluble pattern recognition receptor PTX3

OBJECTIVE

The signals causing the resolution of muscle inflammation are only partially characterized. The long pentraxin PTX3, which modulates leukocyte recruitment and activation, could contribute.

METHODS

We analysed the expression of ptx3 after muscle injury and verified whether hematopoietic precursors are a source of the protein. The kinetics of regeneration and leukocytes infiltration, the accumulation of cell remnants and anti-histidyl-t-RNA synthetase autoantibodies were compared in wild-type and ptx3-deficient mice.

RESULTS

Ptx3 expression was up-regulated three-five days after injury and restricted to the extracellular matrix. Cellular debris and leukocytes persisted in the muscle of ptx3-deficient mice for a long time after wild-type animals had healed. ptx3-deficient macrophages expressed receptors involved in apoptotic cell clearance and engulfed dead cells in vitro. Accumulation of cell debris in a pro-inflammatory microenvironment was not sufficient to elicit autoantibodies.

CONCLUSION

PTX3 generated in response to muscle injury prompts the clearance of debris and the termination of the inflammatory response.

The Repair of Skeletal Muscle Requires Iron Recycling through Macrophage Ferroportin

Macrophages recruited at the site of sterile muscle damage play an essential role in the regeneration of the tissue. In this article, we report that the selective disruption of macrophage ferroportin (Fpn) results in iron accumulation within muscle-infiltrating macrophages and jeopardizes muscle healing, prompting fat accumulation. Macrophages isolated from the tissue at early time points after injury express ferritin H, CD163, and hemeoxygenase-1, indicating that they can uptake heme and store iron. At later time points they upregulate Fpn expression, thus acquiring the ability to release the metal. Transferrin-mediated iron uptake by regenerating myofibers occurs independently of systemic iron homeostasis. The inhibition of macrophage iron export via the silencing of Fpn results in regenerating muscles with smaller myofibers and fat accumulation. These results highlight the existence of a local pathway of iron recycling that plays a nonredundant role in the myogenic differentiation of muscle precursors, limiting the adipose degeneration of the tissue.

Leukocytes recruited by tumor-derived HMGB1 sustain peritoneal carcinomatosis

The factors that determine whether disseminated transformed cells in vivo yield neoplastic lesions have only been partially identified. We established an ad hoc model of peritoneal carcinomatosis by injecting colon carcinoma cells in mice. Tumor cells recruit inflammatory leukocytes, mostly macrophages, and generate neoplastic peritoneal lesions. Phagocyte depletion via clodronate treatment reduces neoplastic growth. Colon carcinoma cells release a prototypic damage-associated molecular pattern (DAMP)/alarmin, High Mobility Group Box1 (HMGB1), which attracts leukocytes. Exogenous HMGB1 accelerates leukocyte recruitment, macrophage infiltration, tumor growth and vascularization. Lentiviral-based HMGB1 knockdown or pharmacological interference with its extracellular impair macrophage recruitment and tumor growth. Our findings provide a preclinical proof of principle that strategies based on preventing HMGB1-driven recruitment of leukocytes could be used for treating peritoneal carcinomatosis.

Required role of apoptotic myogenic precursors and toll-like receptor stimulation for the establishment of autoimmune myositis in experimental murine models

OBJECTIVE

Muscle regeneration is a hallmark of the idiopathic inflammatory myopathies (IIMs), a group of autoimmune disorders that are characterized by leukocyte infiltration and dysfunction of the skeletal muscle. Despite detailed studies describing the clinical and histopathologic features of IIMs, the immunopathogenesis of these disorders remains undefined. The aim of this study was to investigate the immunopathologic processes of autoimmune myositis in experimental murine models.

METHODS

Expression of the autoantigen histidyl-transfer RNA synthetase (HisRS) was analyzed in mice with acutely injured or dystrophic muscles, in inflammatory leukocytes, and in purified satellite cells. Anti-HisRS antibodies and myositis induction were assessed in mice after muscle injury and immunization with apoptotic satellite cells or C2C12 myoblasts, in the presence or absence of the Toll-like receptor 7 (TLR-7) agonist R848.

RESULTS

Muscle necrosis, leukocyte infiltration, and myofiber regeneration induced by toxic agents (cardiotoxin or glycerol) or promoted by genetic disruption of the α-sarcoglycan/dystrophin complex in mice were uniformly associated with up-regulated expression of HisRS. Although regenerating myofibers and purified satellite cells are known to show increased expression of HisRS in these settings, anti-HisRS antibodies were not detectable. However, intramuscular immunization with ultraviolet B-irradiated, HisRS-expressing apoptotic myoblasts in the presence of R848 triggered the production of anti-HisRS IgG antibodies as well as persistent lymphocyte infiltration and prolonged/delayed muscle regeneration. Conversely, intramuscular administration of R848 alone or in combination with living or postapoptotic/necrotic myoblasts failed to generate this myositis phenotype.

CONCLUSION

In the presence of TLR/adjuvant signals and underlying muscle injury, apoptotic myogenic precursors expressing high levels of autoantigen can provoke autoantibody formation and lymphocytic infiltration of muscle tissue, effectively replicating the features of IIM.

Vessel-associated myogenic precursors control macrophage activation and clearance of apoptotic cells

Swift and regulated clearance of apoptotic cells prevents the accumulation of cell remnants in injured tissues and contributes to the shift of macrophages towards alternatively activated reparatory cells that sustain wound healing. Environmental signals, most of which are unknown, in turn control the efficiency of the clearance of apoptotic cells and as such determine whether tissues eventually heal. In this study we show that vessel-associated stem cells (mesoangioblasts) specifically modulate the expression of genes involved in the clearance of apoptotic cells and in macrophage alternative activation, including those of scavenger receptors and of molecules that bridge dying cells and phagocytes. Mesoangioblasts, but not immortalized myoblasts or neural precursor cells, enhance CD163 membrane expression in vitro as assessed by flow cytometry, indicating that the effect is specific. Mesoangioblasts transplanted in acutely or chronically injured skeletal muscles determine the expansion of the population of CD163(+) infiltrating macrophages and increase the extent of CD163 expression. Conversely, macrophages challenged with mesoangioblasts engulf significantly better apoptotic cells in vitro. Collectively, the data reveal a feed-forward loop between macrophages and vessel-associated stem cells, which has implications for the skeletal muscle homeostatic response to sterile injury and for diseases in which homeostasis is jeopardized, including muscle dystrophies and inflammatory myopathies.

Leukocyte HMGB1 is required for vessel remodeling in regenerating muscles

Signals of tissue necrosis, damage-associated molecular patterns (DAMPs), cause inflammation. Leukocytes migrating into injured tissues tonically release DAMPs, including the high mobility group box 1 protein (HMGB1). In the absence of suitable models, the relative role of DAMPs released because of necrosis or leukocyte activation has not, so far, been dissected. We have generated a mouse model lacking Hmgb1 in the hematopoietic system and studied the response to acute sterile injury of the skeletal muscle. Regenerating fibers are significantly less numerous at earlier time points and smaller at the end of the process. Leukocyte Hmgb1 licenses the skeletal muscle to react to hypoxia, to express angiopoietin-2, and to initiate angiogenesis in response to injury. Vascularization of the regenerating tissue is selectively jeopardized in the absence of leukocyte Hmgb1, revealing that it controls the nutrient and oxygen supply to the regenerating tissue. Altogether, our results reveal a novel nonredundant role for leukocyte Hmgb1 in the repair of injured skeletal muscle.

Acid sphingomyelinase determines melanoma progression and metastatic behaviour via the microphtalmia-associated transcription factor signalling pathway

Melanoma is a rapidly growing and highly metastatic cancer with high mortality rates, for which a resolutive treatment is lacking. Identification of novel therapeutic strategies and biomarkers of tumour stage is thus of particular relevance. We report here on a novel biomarker and possible candidate therapeutic target, the sphingolipid metabolising enzyme acid sphingomyelinase (A-SMase). A-SMase expression correlates inversely with tumour stage in human melanoma biopsies. Studies in a mouse model of melanoma and on cell lines derived from mouse and human melanomas demonstrated that A-SMase levels of expression actually determine the malignant phenotype of melanoma cells in terms of pigmentation, tumour progression, invasiveness and metastatic ability. The action of A-SMase is mediated by the activation of the extracellular signal-regulated kinase, the subsequent proteasomal degradation of the Microphtalmia-associated transcription factor (Mitf) and inhibition of cyclin-dependent kinase 2, Bcl-2 and c-Met, downstream targets of Mitf involved in tumour cell proliferation, survival and metastatisation.

Magnetic resonance imaging at 7T reveals common events in age-related sarcopenia and in the homeostatic response to muscle sterile injury

Skeletal muscle remodeling in response to various noxae physiologically includes structural changes and inflammatory events. The possibility to study those phenomena in-vivo has been hampered by the lack of validated imaging tools. In our study, we have relied on multiparametric magnetic resonance imaging for quantitative monitoring of muscle changes in mice experiencing age-related sarcopenia or active regeneration after sterile acute injury of tibialis anterior muscle induced by cardiotoxin (CTX) injection. The extent of myofibrils’ necrosis, leukocyte infiltration, and regeneration have been evaluated and compared with parameters from magnetic resonance imaging: T2-mapping (T2 relaxation time; T2-rt), diffusion-tensor imaging (fractional anisotropy, F.A.) and diffusion weighted imaging (apparent diffusion coefficient, ADC). Inflammatory leukocytes within the perimysium and heterogeneous size of fibers characterized aged muscles. They displayed significantly increased T2-rt (P<0.05) and F.A. (P<0.05) compared with young muscles. After acute damage T2-rt increased in otherwise healthy young muscles with a peak at day 3, followed by a progressive decrease to basal values. F.A. dropped 24 hours after injury and afterward increased above the basal level in the regenerated muscle (from day 7 to day 15) returning to the basal value at the end of the follow up period. The ADC displayed opposite kinetics. T2-rt positively correlated with the number of infiltrating leucocytes retrieved by immunomagnetic bead sorting from the tissue (r = 0.92) and with the damage/infiltration score (r = 0.88) while F.A. correlated with the extent of tissue regeneration evaluated at various time points after injury (r = 0.88). Our results indicate that multiparametric MRI is a sensitive and informative tool for monitoring inflammatory and structural muscle changes in living experimental animals; particularly, it allows identifying the increase of T2-rt and F.A. as common events reflecting inflammatory infiltration and muscle regeneration in the transient response of the tissue to acute injury and in the persistent adaptation to aging.

The selective vitamin D receptor agonist, elocalcitol, reduces endometriosis development in a mouse model by inhibiting peritoneal inflammation

BACKGROUND

Endometriosis, which is characterized by the growth of endometrial tissue at ectopic locations as well as vascular development and inflammation, is still an unmet clinical need since an optimal drug that allows for both pain and infertility management does not exist. Since both the eutopic and the ectopic endometrium express the vitamin D receptor (VDR), and VDR agonists are endowed with anti-proliferative and anti-inflammatory properties, we evaluated the effect of elocalcitol, a VDR agonist with low calcaemic liability, in a mouse model of experimentally induced endometriosis.

METHODS AND RESULTS

Endometriosis was induced by injection of syngeneic endometrial tissue fragments into adult Balb/c female mice. After having confirmed by immunohistochemistry that endometriotic lesions developing in mice expressed VDR, the mice were administered with elocalcitol (100 μg/kg) or vehicle orally, once a day, for various durations of time. In this model, elocalcitol was able to reduce total lesion weight up to 70% upon treatment for 1 week before and 2 weeks after disease induction. Interestingly, a therapeutic effect was also observed on already established lesions. Elocalcitol was shown to reduce the capacity of mouse endometrial cells to adhere to collagen. In addition in treated mice, a decreased state of peritoneal inflammation was demonstrated by the inhibition of macrophage recruitment and inflammatory cytokine secretion.

CONCLUSIONS

The VDR agonist elocalcitol inhibits lesion development in a validated mouse model of endometriosis, and exerts a protective effect on both the implantation and organization of transferred endometrial tissue. These preliminary data in mice provide a sound rationale for further testing in primate models and eventually in humans.

Abstract 316: Peritoneal carcinomatosis depends for growth and spreading on endogenous inflammatory cues generated by infiltrating macrophages

Peritoneal carcinomatosis is the most common terminal feature of abdominal cancers. Interfering with the peritoneal immune microenvironment is a promising tool for combinational therapy. Preclinical studies on peritoneal carcinomatosis have been hampered by the limited availability of models as well as non-invasive methods to follow tumor growth. We set up ad hoc models via the orthotopic injection of murine cells lines in immuno-competent mice and followed tumor growth by imaging with [18F]2-fluoro-2-deoxy-D-glucose-PET ([18F]-FDG-PET). Colon carcinoma (MC38), Mouse Ovarian Surface Epithelial Carcinoma cell line (MOSEC) of C57BL/6 origin and adenocarcinoma cells (TS/A) of Balb/C origin were injected intraperitoneally in syngeneic mice. The models nicely recapitulated the histological features of the human disease: carcinoma cells distributed along the cavity and yielded several masses attached to the peritoneal lining. Animals were longitudinally followed by imaging with [18F]-FDG-PET: tumor lesions selectively up-took the radioactive tracer and we observed a significant correlation between lesion dimension and metabolic radioactive volume. We characterized leukocyte composition of the peritoneal liquid of tumor bearing mice by multicolor flow cytometry, performing peritoneal lavage on live animals at various time points during tumor growth. Tumor spreading induced the recruitment of leukocytes, among which the most relevant population was represented by CD45+CD11b+F4/80+ monocytes/macrophages. The depletion of peritoneal monocytes/macrophages, via administration of clodronate encapsulated in liposomes, lead to a substantial reduction of tumor burden as well as leukocyte recruitment, and was paralleled by a decrement in the extent of radioactivity distribution when imaging mice with [18F]-FDG-PET. Moreover we found out that colon carcinoma cells upon in-vitro treatment with stress-inducing stimuli, such as starvation and chemotherapeutic agents exposure, produced factors involved in leukocytes recruitment: this behavior was directly linked to the activation of autophagic and apoptotic intracellular pathways. In conclusion, [18F]-FDG-PET imaging allowed the non-invasive detection of peritoneal adenocarcinoma lesions which spreading and growth was dependent on the production of factors involved in leukocytes recruitment, specifically on peritoneal monocytes/macrophages.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 316. doi:1538-7445.AM2012-316

High-mobility group box 1 release and redox regulation accompany regeneration and remodeling of skeletal muscle

High-mobility group box 1 (HMGB1), a damage-associated molecular pattern (DAMP) molecules, favors tissue regeneration via recruitment and activation of leukocytes and stem cells. Here we demonstrate, in a model of acute sterile muscle injury, that regeneration is accompanied by active reactive oxygen species (ROS) production counterbalanced and overcome by the generation of antioxidant moieties. Mitochondria are initially responsible for ROS formation. However, they undergo rapid disruption with almost complete disappearance. Twenty-four hours after injury, we observed a strong induction of MURF1 and atrogin-1 ubiquitin ligases, key signals in activation of the proteasome system and induction of muscle atrophy. At later time points, ROS generation is maintained by nonmitochondrial sources. The antioxidant response occurs in both regenerating fibers and leukocytes that express high levels of free thiols and antioxidant enzymes, such as superoxide dismutase 1 (SOD1) and thioredoxin. HMGB1, a protein thiol, weakly expressed in healthy muscles, increases during regeneration in parallel with the antioxidant response in both fibers and leukocytes. A reduced environment may be important to maintain HMGB1 bioactivity. Indeed, oxidation abrogates both muscle stem cell migration in response to HMGB1 and their ability to differentiate into myofibers in vitro. We propose that the early antioxidant response in regenerating muscle limits HMGB1 oxidation, thus allowing successful muscle regeneration.

Proangiogenic Tie2(+) macrophages infiltrate human and murine endometriotic lesions and dictate their growth in a mouse model of the disease

Endometriosis affects women of reproductive age, causing infertility and pain. Although immune cells are recruited in endometriotic lesions, their role is unclear. Tie2-expressing macrophages (TEMs) have nonredundant functions in promoting angiogenesis and growth of experimental tumors. Here we show that human TEMs infiltrate areas surrounding newly formed endometriotic blood vessels. We set up an ad hoc mouse model in which TEMs, and not Tie2-expressing endothelial cells, are targeted. We transplanted in wild-type recipients bone marrow cells expressing a suicide gene (Herpes simplex virus type 1 thymidine kinase) under the Tie2 promoter/enhancer. TEMs infiltrated endometriotic lesions. TEM depletion by ganciclovir administration arrested the growth of established lesions, without toxicity. Lesion architecture was disrupted, with: i) loss of glandular organization, ii) reduced neovascularization, and iii) activation of caspase 3 in CD31(+) endothelial cells. Thus, TEMs are important for maintaining the viability of newly formed vessels and represent a potential therapeutic target in endometriosis.

Macrophages are alternatively activated in patients with endometriosis and required for growth and vascularization of lesions in a mouse model of disease

The mechanisms that sustain endometrial tissues at ectopic sites in patients with endometriosis are poorly understood. Various leukocytes, including macrophages, infiltrate endometriotic lesions. In this study, we depleted mouse macrophages by means of either clodronate liposomes or monoclonal antibodies before the injection of syngeneic endometrial tissue. In the absence of macrophages, tissue fragments adhered and implanted into the peritoneal wall, but endometriotic lesions failed to organize and develop. When we depleted macrophages after the establishment of endometriotic lesions, blood vessels failed to reach the inner layers of the lesions, which stopped growing. Macrophages from patients with endometriosis and experimental mice, but not nonendometriotic patients who underwent surgery for uterine leiomyomas or control mice, expressed markers of alternative activation. These markers included high levels of scavenger receptors, CD163 and CD206, which are involved in both the scavenging of hemoglobin with iron transfer into macrophages and the silent clearance of inflammatory molecules. Macrophages in both inflammatory liquid and ectopic lesions were equally polarized, suggesting a critical role of environmental cues in the peritoneal cavity. Adoptively transferred, alternatively activated macrophages dramatically enhanced endometriotic lesion growth in mice. Inflammatory macrophages effectively protected mice from endometriosis. Therefore, endogenous macrophages involved in tissue remodeling appear as players in the natural history of endometriosis, required for effective vascularization and ectopic lesion growth.

Characterization of innate responses elicited by neoadjuvant radio-chemotherapy for rectal cancer

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Background: The neoadjuvant chemo-radiotherapy (CT-RT) has improved the treatment of locally advanced rectal cancer reducing the local recurrence. However a survival benefit has not been reached yet. In order to increase the rate of pathological complete remissions in our Institution we intensified both the CT schedule adding oxaliplatin to 5-FU and the RT program with tomotherapy. The aim of this study was to verify: whether the pattern of innate response elicited by the neoadjuvant CT-RT is heterogeneous among pts and whether this information can be used to identify which pts will benefit from the treatment. Methods: We collected samples of T3N+M0 rectal cancer pts before, during and after neoadjuvant CT-RT (3 cycles of oxaliplatin + 5-FU; 45 Gy). At each time point we characterized circulating monocytes by flow cytometry, infiltrating macrophages by immunoistochemistry (IHC) and selected inflammatatory molecules by ELISA.Results: We recruited so far 25 pts, of whom 10 have reached the surgery with three pathological complete remission and four down staging. No substantial changes were detectable in the number of circulating monocytes. In contrast we observed a clear expansion of CD14/CD86 and CD14/CD163 double positive subsets. This event was transient and apparently causally related to the treatment since it abated at the later time point. Moreover, it correlated with sensitivity to the treatment: 5/7 pts who underwent disease regression had an early and transitory increase of the number of CD14/CD86 and CD14/CD163 positive cells, which was absent or negligible in non responder pts. The IHC study revealed a massive tumoral infiltration by macrophages which displayed clear features of alternative M2 polarization as assessed by expression of the CD163 and 206 scavenger receptors. A subset of pts had elevated PTX3 and low CRP concentration at the onset of treatment. PTX3 concentration abated after the first CT cycle. Conclusions: These data suggest that neoadjuvant CT-RT modulates the cellular components of innate immune responses, that could represent valuable predictive factors.

No significant financial relationships to disclose.

Maturing dendritic cells depend on RAGE for in vivo homing to lymph nodes

The mobilization of dendritic cells (DCs) from peripheral tissues is critical for the establishment of T cell-dependent immune responses or tolerance, because the physical interaction of DCs with naive T cells takes place in the T cell areas of lymph nodes. The autocrine/paracrine release of the high mobility group box 1 (HMGB1) nuclear protein by DCs controls the outcome of the DC-T cell interaction, influencing the priming/Th1 polarization of naive T cells. We herein present evidence that the receptor for advanced glycation end products (RAGE), a multiligand member of the Ig superfamily of cell-surface molecules that acts as a receptor for HMGB1, plays a nonredundant role in DC homing to lymph nodes. We used noninvasive imaging by magnetic resonance and immunohistochemistry to track DCs after s.c. injection in the footpad of wild-type(+/+) or RAGE(-/-) mice. Maturing DCs expressing RAGE effectively migrated in both conditions. In contrast, RAGE(-/-) DCs failed to reach the draining popliteal lymph nodes of +/+ and -/- mice, indicating that the integrity of RAGE is required for DC mobilization. Thus the HMGB1-RAGE pathway is a checkpoint in DC maturation and function and a candidate for targeted therapies.

Pigment identification on "Pietà" of Barletta, example of Renaissance Apulian sculpture: a Raman microscopy study

A study of the original painting layer of the "Pietà" of Barletta, a polychrome statue, important example of Renaissance Apulian sculpture, was performed by mu-Raman spectroscopy. Vermilion was identified in the original layer of the blood drops on Jesus knee. Lazurite was identified as the original blue pigment on Our Lady's veil and lace, currently a yellow ochre-like color. The use of lazurite demonstrates the historical-artistic importance of this polychrome statue, and supports the hypothesis that this artwork was probably commissioned by Our Lady's devotees to itinerant artists inspired by the more precious Vesperbilder model.

Peripheral T cell tolerance occurs early during spontaneous prostate cancer development and can be rescued by dendritic cell immunization

In the tumor-prone transgenic adenocarcinoma mouse prostate (TRAMP) mouse model we followed the fate of the immune response against the SV40 large T antigen (Tag) selectively expressed in the prostate epithelium during the endogenous transformation from normal cells to tumors. Young (5-7-week-old) male TRAMP mice, despite a dim and patchy expression of Tag overlapping foci of mouse prostate intraepithelial neoplasia, displayed a strong Tag-specific cytotoxic T lymphocyte (CTL) response after an intradermal injection of peptide-pulsed dendritic cells (DC). This response was weaker than the one found in vaccinated wild-type littermates, and was characterized by a reduced frequency and avidity of Tag-specific CTL. Early DC vaccination also subverted the profound state of peripheral tolerance typically found in TRAMP mice older than 9-10 weeks. The DC-induced CTL response indeed was still detectable in TRAMP mice of 16 weeks, and was associated with histology evidence of reduced disease progression. Our findings suggest that tumor antigens are handled as self antigens, and peripheral tolerance is associated with in situ antigen overexpression and cancer progression. Our data also support a relevant role for DC-based vaccines in controlling the induction of peripheral tolerance to tumor antigens.

Production of profibrotic cytokines by invariant NKT cells characterizes cirrhosis progression in chronic viral hepatitis

Invariant (inv)NKT cells are a subset of autoreactive lymphocytes that recognize endogenous lipid ligands presented by CD1d, and are suspected to regulate the host response to cell stress and tissue damage via the prompt production of cytokines. We investigated invNKT cell response during the progression of chronic viral hepatitis caused by hepatitis B or C virus infection, a major human disease characterized by a diffused hepatic necroinflammation with scarring fibrotic reaction, which can progress toward cirrhosis and cancer. Ex vivo frequency and cytokine production were determined in circulating and intrahepatic invNKT cells from controls (healthy subjects or patients with nonviral benign or malignant focal liver damage and minimal inflammatory response) or chronic viral hepatitis patients without cirrhosis, with cirrhosis, or with cirrhosis and hepatocellular carcinoma. invNKT cells increase in chronically infected livers and undergo a substantial modification in their effector functions, consisting in the production of the type 2 profibrotic IL-4 and IL-13 cytokines, which characterizes the progression of hepatic fibrosis to cirrhosis. CD1d, nearly undetectable in noncirrhotic and control livers, is strongly expressed by APCs in cirrhotic ones. Furthermore, in vitro CD1d-dependent activation of invNKT cells from healthy donors elicits IL-4 and IL-13. Together, these findings show that invNKT cells respond to the progressive liver damage caused by chronic hepatitis virus infection, and suggest that these cells, possibly triggered by the recognition of CD1d associated with viral- or stress-induced lipid ligands, contribute to the pathogenesis of cirrhosis by expressing a set of cytokines involved in the progression of fibrosis.

TNF-α Coupled to Membrane of Apoptotic Cells Favors the Cross-Priming to Melanoma Antigens

The cross-presentation of Ags derived from apoptotic cell processing contributes to peripheral tolerance. Environmental signals possibly modify this default outcome, favoring cross-priming. In this study, we anchored via a biotin-avidin-biotin bridge soluble TNF-alpha to the membrane of apoptotic melanoma cells and studied in vivo and in vitro the interaction with Ag-presenting phagocytes. TNF-alpha-coated apoptotic melanoma cells injected s.c. had a faster and more efficient access to draining lymph nodes, with cross-priming of melanoma-specific CTLs and delayed outgrowth of melanomas in all treated animals. Twenty percent of the animals, in the absence of further adjuvant, did not develop the tumor. Immature dendritic cells challenged with TNF-alpha-coated apoptotic melanoma cells secreted proinflammatory cytokines in an autocrine/paracrine fashion, efficiently matured, as assessed functionally and by flow cytometry and cross-presented with enhanced efficiency melanoma Ags to MHC class I- and II-restricted T cells. The results indicate that TNF-alpha targeted to apoptotic membranes, at concentrations that can be safely reached in growing tumors without undue systemic toxicity, influences the outcome of the disposal of dying cells and enhances tumor immunogenicity.

Attentional demands reflect learning-induced alterations of bimanual coordination dynamics

This study aimed to investigate the effects of practice on bimanual coordination dynamics and attentional demands. Participants were asked to perform a dual-task associating a cyclic antiphase bimanual pattern and a discrete reaction time task. A pretest determined each individual critical transition frequency. In the training session, participants practised 120 trials. They were instructed to maintain the antiphase coordination pattern at the critical transition frequency. The training session was interrupted and followed by an intermediate test (after 60 trials) and a post-test (30 min after 120 trials), respectively. A retention test was performed 7 days after the end of the training session. Results showed that: (i) the number of transitions decreased as a consequence of practice; and (ii), subjects were able to maintain the antiphase pattern at a higher frequency than in the pretest. Analysis of the trade-off between relative phase variability and reaction time showed that participants were able to maintain a higher level of stability at the same (intermediate and post-test) or a lower attentional cost (retention test). These findings show that phase transition dynamics and pattern stability can be significantly modified as a result of practice. Changes in the trade-off between pattern stability and cost with learning confirm that the attentional cost incurred by the central nervous system to maintain pattern stability decreased with practice. In line with recent neurobiological studies, the present study provides new insights regarding relationships between brain processes, attentional demands and coordinated behaviour in learning bimanual patterns.

Chromogranin A expression in neoplastic cells affects tumor growth and morphogenesis in mouse models

Chromogranin A (CgA), a secretory protein expressed by many neuroendocrine cells, has been recognized as a useful tissue and serum marker of neuroendocrine tumors. To investigate the effect of CgA secretion on neoplastic morphogenesis and progression, we have transfected mouse RMA lymphoma and TS/A adenocarcinoma cells with the cDNA encoding human CgA and selected several CgA-positive (secreting) and CgA-negative (nonsecreting) clones. In both models, the growth rate of CgA-positive clones implanted s.c. in nude mice was slower than that of CgA-negative clones. Histological analysis of each RMA tumor showed that CgA-expression was associated with multinodular growth patterns, whereas CgA-negative tumors appeared more compact and similar to wild-type RMA tumors. Moreover, CgA production was associated with increased tumor necrosis. The number of nodules in each RMA tumor correlated with the serum levels of CgA (n = 40, r = 0.537, P = 0.0004). The reduced growth rate of CgA-positive RMA and TS/A tumors was not related to reduced in vitro proliferation or to changes in cell adhesion and shape, suggesting that the mechanism is indirect and host-mediated. These results suggest that abnormal secretion of CgA by neuroendocrine neoplastic cells could affect neoplastic growth and morphogenesis.

A dynamical framework to understand performance trade-offs and interference in dual tasks

This study demonstrated that the dynamic pattern approach may reconcile resource and outcome conflict theories to explain performance in dual tasks. Participants performed a bimanual coordination task and a reaction time task with different conditions of attentional priority. Results showed a trade-off between pattern variability and reaction time when priority was given to the coordination task. Such a trade-off was indicative of resource allocation. An analysis of perturbation in the bimanual coordination revealed interference, a reputed sign of outcome conflict. Moreover, interference diminished substantially when priority was given to the bimanual task. The coexistence of performance trade-off and outcome conflict suggests that these two phenomena are not mutually exclusive. Rather, both may follow from modifying the coupling between the limbs through attention.

Shared dynamics of attentional cost and pattern stability

This paper examines the informational activity devoted by the CNS to couple oscillating limbs in order to sustain and stabilize bimanual coordination patterns. Through a double-task paradigm associating a bimanual coordination task and a reaction time (RT) task, we investigated the relation between the stability of preferred bimanual coordination patterns and the central cost expended by the CNS for their stabilization. Ten participants performed in-phase and anti-phase coordination patterns in a dual task condition (coordination + RT) at several frequencies (0.5, 0.75, 1.0, 1.5, and 2.0 Hz), thereby decreasing the stability of the bimanual patterns. Results showed a U-shaped evolution of pattern stability and attentional cost, as a function of oscillation frequency, exhibiting a minimum value at the same frequency. These findings indicate that central cost and pattern stability covary and may share common, high order dynamics. Moreover, the attentional focus given to the bimanual coordination and the RT task was also manipulated by requiring either shared attention or priority to the coordination task. Such a manipulation led to a tradeoff between pattern stability and RT performance: The more stable the pattern, the more costly it is to stabilize. This suggests that stabilizing a coordination pattern incurs a central cost that depends on its intrinsic stability. Conceptual consequences of these results for understanding the relationship between attention and coordination are drawn, and the mechanisms putatively at work in dual tasks are discussed.

Effects of attention on phase transitions between bimanual coordination patterns: a behavioral and cost analysis in humans

The present study aimed to obtain a behavioral analysis of the effects of attentional focus on the dynamics of phase transitions in bimanual coordination and to evaluate the central cost expended by the central nervous system to maintain and stabilize such coordination patterns before and after the transition. Eight subjects were asked to execute an anti-phase coordination pattern (180 degrees of relative phase), while gradually increasing the frequency of oscillation. The central cost was assessed using a dual-task paradigm associating the bimanual coordination task with a reaction time task. Results showed that: (1) the transition process was significantly altered by focusing attention on the bimanual coordination task; and (2) the cost involved in sustaining the bimanual patterns was determined by their coordination dynamics.

Electrical kindling is associated with a lasting increase in the extracellular levels of kynurenic acid in the rat hippocampus

Endogenous kynurenic acid (KYNA), an excitatory amino acid receptor antagonist with antineurotoxic and anticonvulsant activity, was assessed by microdialysis in the hippocampus of kindled rats. One week after the completion of amygdala or hippocampal kindling (stage 5), the dialysate concentration of KYNA in the hippocampus of both hemispheres was 1.7 +/- 0.1-fold higher than in shams (P < 0.01). Veratridine (50 microM), applied through the probe, reduced extracellular KYNA by 28% within 1 h in controls (P < 0.05), but was ineffective in stage 5 kindled rats. At the preconvulsive stage 2, dialysate KYNA concentration and the effect of veratridine were similar to controls. The activity of KYNA's biosynthetic enzyme, kynurenine aminotransferase, did not change in the hippocampus 1 week after stage 5 seizures. These data indicate an enhanced liberation of KYNA in teh hippocampus of fully kindled animals due to an impairment of normal regulatory mechanisms. This may be of relevance for the control of hippocampal excitability during epileptogenesis.

Extracellular glutamate levels in the hypothalamus and hippocampus of rats after acute or chronic oral intake of monosodium glutamate

Using brain microdialysis we studied the effect of high doses of monosodium glutamate (MSG) on the extracellular concentration of glutamate in the hypothalamus and in the hippocampus of freely moving rats. MSG at 4 g/kg (40% solution) given by gavage caused a significant increase in plasma (5.3 +/- 0.4-fold, P < 0.01) and extracellular glutamate in the hippocampus (4.2 +/- 0.6-fold, P < 0.01) and in the hypothalamus (8.9 +/- 1.7-fold, P < 0.01) compared to control rats receiving a 40% sucrose solution (10 ml/kg). The peak increase was found within 40 min after MSG administration then declining to baseline in the next 80 min. No changes were found in glutamate tissue concentrations. Twenty-one days after ad libitum MSG intake with the diet (approximately 4 g/kg) no changes were found, in plasma, in extracellular and tissue concentration of glutamate in the hypothalamus compared to rats fed with a normal diet. Glutamate release induced by 200 mM KCl was not modified as well. Histological analysis of Nissl-stained brain tissue slices did not reveal any obvious cell loss in the hippocampus after acute or chronic MSG administration.

Enhanced neuropeptide Y release in the hippocampus is associated with chronic seizure susceptibility in kainic acid treated rats

We measured the release of neuropeptide Y (NPY) from hippocampal slices of rats at various times after limbic seizures induced by a subcutaneous injection of 12 mg/kg kainic acid (KA). Two days after KA, 100 mM KCl induced a 1.6 +/- 0.2-fold increase in NPY release compared to saline-injected rats (P < 0.05), while spontaneous and 50 mM KCl-induced release were unchanged. Thirty days after KA, the spontaneous and 100 mM KCl-induced efflux of NPY was enhanced 2-fold on average (P < 0.01) compared to controls, while no significant differences were found using 50 mM KCl. Tissue concentration of NPY was raised 2.2 +/- 0.2 times (P < 0.01) 30 days after KA. Thirty days after KA, the rats showed enhanced susceptibility to tonic-clonic seizures, assessed using a normally subconvulsive dose of pentylenetetrazol (PTZ; 30 mg/kg). A selective antibody (Ab) raised against NPY in a rabbit was infused bilaterally for three days in the CA3 area and dentate gyrus (DG) of the dorsal hippocampus of rats treated 30 days before with KA. This significantly reduced (P < 0.05) the number of animals with tonic-clonic seizures induced by 30 mg/kg PTZ, compared to KA treated rats which received the inactivated Ab. The Ab was ineffective in naive rats injected with a full convulsive dose of PTZ (55 mg/kg). The present results show that neuronal release of NPY is enhanced in the hippocampus after limbic seizures induced in rats by KA. This effect persists for at least 30 days and may contribute to the chronically enhanced susceptibility to seizures after injection of this toxin.

Electrical kindling of the hippocampus is associated with functional activation of neuropeptide Y-containing neurons

The release of neuropeptide Y (NPY) was measured from hippocampal slices of rats at stage 2 (preconvulsive stage) and stage 5 (full seizure expression) of electrical kindling of the dorsal hippocampus (upper blade of the dentate gyrus). Spontaneous release in naive rats (9.0 +/- 0.8 fmol/ml every 10 min) was independent of external Ca2+ but was reduced by 38 +/- 3.6% (P < 0.05) during 20 min incubation with 5 microM tetrodotoxin. Spontaneous efflux in naive rats did not differ from that in shams (implanted with electrodes but not stimulated) or in rats kindled to stage 2 and stage 5. Twenty-five, 50 and 100 mM KCl induced a concentration-dependent release of NPY (P < 0.05 and P < 0.01 at 25 and 50-100 mM respectively) from slices of shams. The effect of 100 mM KCl was reduced by 94 +/- 1% (P < 0.01) in the absence of Ca2+. Two days after the last stage 2 stimulation and 1 week after the last stage 5 seizure, NPY release was significantly larger than in shams at all KCl concentrations in the stimulated and contralateral hippocampus (P < 0.05 and P < 0.01). Forty-eight hours after one single after-discharge and 1 month after the last stage 5 seizure, 50 mM KCl induced a significantly larger release of NPY in the stimulated and contralateral hippocampus (P < 0.01 and P < 0.05), although the effect was less than during kindling.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracellular somatostatin measured by microdialysis in the hippocampus of freely moving rats: evidence for neuronal release

Intracerebral microdialysis combined with a sensitive and specific radioimmunoassay was used to monitor the neuronal release of somatostatin (somatostatin-like immunoreactivity, SLI) in the dorsal hippocampus of freely moving rats. The sensitivity of the radioimmunoassay was optimized to detect < 1 fmol/ml. The basal concentration of SLI in 20-min dialysate fractions (5 microliters/min) collected 24 h after probe implantation was stable over at least 200 min. The spontaneous efflux dropped by 54 +/- 6.4% (p < 0.05) when Ca2+ was omitted and 1 mM EGTA added to the Krebs-Ringer solution and by 65.5 +/- 3.2% (p < 0.05) in the presence of 1 microM tetrodotoxin. Depolarizing concentrations of the Na+ channel opener veratridine (6.25, 25, 100 microM) induced 11 +/- 2 (p < 0.05), 17 +/- 2 (p < 0.05), and 21 +/- 5 (p < 0.01) fold increase in SLI concentration, respectively, during the first 20 min of perfusion. The effect of 100 microM veratridine was blocked by coperfusion with 5 microM tetrodotoxin (p < 0.01) and reduced by 79% (p < 0.01) in the virtual absence of Ca2+. Neuronal depolarization by 20 min of perfusion with Krebs-Ringer solution containing 25 and 50 mM KCl and proportionally lowered Na+ increased the dialysate SLI 4.4 +/- 1 (p < 0.05) and 17 +/- 3 (p < 0.01) fold baseline, respectively. Ten micromolar ouabain, a blocker of Na+,K(+)-ATPase, increased the dialysate SLI 15-fold baseline, on average (p < 0.05), during 80 min of perfusion. The results demonstrate the suitability of brain microdialysis for monitoring the neuronal release of SLI and for studying its role in synaptic transmission.

Anti-somatostatin antibody enhances the rate of hippocampal kindling in rats

A somatostatin-specific antibody (Ab) (1:250) was continuously infused into the stimulated dorsal hippocampus of rats from 4 days before to 26 days after the beginning of kindling or until the first stage 5. Controls received boiled Ab. The number of stimulations to the first stage 5 were reduced by 41 +/- 4% (P < 0.01, Student's t-test) in animals infused with the Ab compared to controls. The cumulative after-discharge in the stimulated hippocampus was slightly, although not significantly, reduced. Kindling was not affected when the Ab was infused only during the first 10 stimulations (stage 2). Histological analysis showed no neurotoxic effects in the hippocampus as a consequence of Ab infusion.