In vitro analysis of carotid lesions using a preliminary microwave sensor to detect vulnerable plaques: Correlation with histology, Duplex ultrasound examination, and computed tomography scanner: The Imaging and Microwave Phenotyping Assessment of Carotid stenosis Threat (IMPACT) study

Objective

Progress in best medical treatment have made identification of best candidates for carotid surgery more difficult. New diagnostic modalities could be helpful in this perspective. Microwaves (MWs) can quantify dielectric properties (complex relative permittivity) of biological tissues and MW technology has emerged as a promising field of research for distinguishing abnormal tissues from healthy ones. We here evaluated the ability of a dedicated MW sensor developed in our laboratory to identify vulnerable carotid lesions.

Methods

We included 50 carotid lesions in this study. The plaques were analyzed and classified preoperatively by ultrasound (US) examination, computed tomography angiography and tested postoperatively using a MW sensor. Histopathological analysis was used as a gold standard to separate vulnerable plaques (VPs) from nonvulnerable plaques (NVPs).

Results

VPs were more frequently types 2 or 3 plaques (on US examination), had a greater proportion of low (<60 Hounsfield unit) and moderate (60-130 Hounsfield unit) attenuation components (computed tomography angiography) and displayed higher dielectric constant values (MW) than NVPs, which had an opposite profile. NVPs were more frequently asymptomatic plaques compared with VPs (P = .035). Multivariate analysis showed that US examination and MW identified VPs with a sensitivity of 77% and a specificity of 76% (cutoff value, -0.045; area under the curve, 0.848; P < .0001).

Conclusions

We found that the presence of types 2 to 3 (on US examination) and high dielectric constant plaques in vitro was highly indicative of a VP based on histological analysis. Further studies are needed to determine the potential of MW to identify the most dangerous asymptomatic carotid lesions.

A New Digital Method for Counting Mast Cells in Cutaneous Specific Lesions of Mastocytosis: A Series of Adult Cases of Mastocytosis With Clinical-Pathological Correlations

ABSTRACT

Cutaneous mastocytosis is characterized by the abnormal accumulation of mast cells in the skin. However, mast cell counting is not always easy and reproducible with classical methods. This work aims to demonstrate the reliability, usability, and virtues of a new software used on digital tablets for counting mast cells in cutaneous specific lesions of mastocytosis, to assess differences in mast cell counts between clinical subtypes of mastocytosis in the skin, and to consider the feasibility of applying a diagnostic mast cell count cutoff to urticaria pigmentosa, which is the most frequent form of cutaneous mastocytosis. Using a new digital tablet software that was accessible by multiple observers through its own wireless network and allowed high resolution of the image without data compression, we counted the number of mast cells on slides of patients and control skins immunostained for CD117. We found that our counting method was highly reproducible and that the new software allowed very quick counting. We evidenced strong differences in the mast cell count between most of the clinical subtypes of mastocytosis in the skin. However, when applied to a subset of patients with urticaria pigmentosa, a diagnostic cutoff in the mast cell count lacked sensitivity. Thus, our digital method for counting CD117-immunostained mast cells was highly accurate and was of a significant value for the diagnosis of mastocytosis in the skin. However, some subtypes with low mast cell counts will still require the application of additional diagnostic criteria.

Immunological environment in colorectal cancer: a computer-aided morphometric study of whole slide digital images derived from tissue microarray

Cancer research has moved from investigating tumour cells to including analysis of the tumour microenvironment as well. The aim of this study was to assess the cellular infiltrate of colorectal cancer (CRC) using computer-aided analysis of whole slide digital image derived from tissue microarray (TMA). TMA slides from 31 CRC patients were immunostained for forkhead box protein 3 (FOXP3) and immunomodulatory enzyme indoleamine 2,3-dioxygenase (IDO) at four sites: centre (C) and invasive front (F) of the tumour, proximal non-metastatic draining lymph node (N-), tumour-draining lymph node with metastasis (N+) and healthy mucosa at 10 cm from the cancer (M). We analysed the proportion of IDO+ tissue areas in the lamina propria or in the non-epithelial area of the lymph node and in epithelial cells in each site. The normal mucosa of patients operated on for benign disease was also analysed. The proportion (%) of FOXP3+ tissue area in C, F, N-, N+ and M were 2.3 ± 1.8, 2.6 ± 2.9, 6.0 ± 2.9, 14.2 ± 5.8 and 1.2 ± 0.8 (p < 0.001). The proportion (%) of IDO+ tissue area in the lamina propria of C, F, N-, N+ and M were 1.6 ± 3.1, 1.1 ± 1.3, 3.4 ± 2.5, 9.1 ± 8.5 and 6.7 ± 5.4 (p < 0.001). IDO+ tissue area in the lamina propria was not significantly different between healthy mucosa of patients with cancer than without (1.8 ± 3 vs 1.1 ± 0.95). The proportion of IDO positive tissue area in the epithelium was significantly higher in healthy mucosa of patients with cancer than without (5.4 ± 13.8 vs 2.1 ± 2.4). The FOXP3+ tissue area was increased in healthy mucosa of CRC patients in comparison with healthy mucosa of patients with colorectal resection for disease other than cancer: 1.20 ± 1.81 versus 0.81 ± 0.51 (p < 0.05). The proportion of IDO+ tissue area in lymph node (N-) was correlated with the proportion of FOXP3+ tissue area in tumour area (r = 0.44, p < 0.01). TMA technique permits simultaneous analysis of FOXP3+ and IDO+ cells at different sites including tumour, draining non-metastatic lymph node, metastatic lymph node and normal mucosa.

The FAT Score, a Fibrosis Score of Adipose Tissue: Predicting Weight-Loss Outcome After Gastric Bypass

CONTEXT

Bariatric surgery (BS) induces major and sustainable weight loss in many patients. Factors predicting poor weight-loss response (PR) need to be identified to improve patient care. Quantification of subcutaneous adipose tissue (scAT) fibrosis is negatively associated with post-BS weight loss, but whether it could constitute a predictor applicable in clinical routine remains to be demonstrated.

OBJECTIVE

To create a semiquantitative score evaluating scAT fibrosis and test its predictive value on weight-loss response after Roux-en-Y gastric bypass (RYGB).

METHODS

We created a fibrosis score of adipose tissue (FAT score) integrating perilobular and pericellular fibrosis. Using this score, we characterized 183 perioperative scAT biopsy specimens from severely obese patients who underwent RYGB (n = 85 from a training cohort; n = 98 from a confirmation cohort). PR to RYGB was defined as <28% of total weight loss at 1 year (lowest tertile). The link between FAT score and PR was tested in univariate and multivariate models.

RESULTS

FAT score was directly associated with increasing scAT fibrosis measured by a standard quantification method (P for trend <0.001). FAT score interobserver agreement was good (κ = 0.76). FAT score ≥2 was significantly associated with PR. The association remained significant after adjustment for age, diabetes status, hypertension, percent fat mass, and interleukin-6 level (adjusted odds ratio, 3.6; 95% confidence interval, 1.8 to 7.2; P = 0.003).

CONCLUSION

The FAT score is a new, simple, semiquantitative evaluation of human scAT fibrosis that may help identify patients with a potential limited weight-loss response to RYGB.

Accumulation and Changes in Composition of Collagens in Subcutaneous Adipose Tissue After Bariatric Surgery

CONTEXT

Extracellular matrix (ECM) in sc adipose tissue (scAT) undergoes pathological remodeling during obesity. However, its evolution during weight loss remains poorly explored.

OBJECTIVE

The objective of the investigation was to study the histological, transcriptomic, and physical characteristics of scAT ECM remodeling during the first year of bariatric surgery (BS)-induced weight loss and their relationships with metabolic and bioclinical improvements.

DESIGN, SETTING, PATIENTS, AND INTERVENTIONS

A total of 118 morbidly obese candidates for BS were recruited and followed up during 1 year after BS.

MAIN OUTCOME MEASURES

scAT surgical biopsy and needle aspiration as well as scAT stiffness measurement were performed in three subgroups before and after BS. Fourteen nonobese, nondiabetic subjects served as controls.

RESULTS

Significantly increased picrosirius-red-stained collagen accumulation in scAT after BS was observed along with fat mass loss, despite metabolic and inflammatory improvements and undetectable changes of scAT stiffness. Collagen accumulation positively associated with M2-macrophages (CD163(+) cells) before BS but negatively afterward. Expression levels of genes encoding ECM components (eg, COL3A1, COL6A1, COL6A2, ELN), cross-linking enzymes (eg, lysyl oxidase [LOX], LOXL4, transglutaminase), metalloproteinases, and their inhibitors were modified 1 year after BS. LOX expression and protein were significantly decreased and associated with decreased fat mass as well as other cross-linking enzymes. Although total collagen I and VI staining decreased 1 year after BS, we found increased degraded collagen I and III in scAT, suggesting increased degradation.

CONCLUSIONS

After BS-induced weight loss and related metabolic improvements, scAT displays major collagen remodeling with an increased picrosirius-red staining that relates to increased collagen degradation and importantly decreased cross-linking. These features are in agreement with adequate ECM adaptation during fat mass loss.

Plasmodium falciparum full life cycle and Plasmodium ovale liver stages in humanized mice

Experimental studies of Plasmodium parasites that infect humans are restricted by their host specificity. Humanized mice offer a means to overcome this and further provide the opportunity to observe the parasites in vivo. Here we improve on previous protocols to achieve efficient double engraftment of TK-NOG mice by human primary hepatocytes and red blood cells. Thus, we obtain the complete hepatic development of P. falciparum, the transition to the erythrocytic stages, their subsequent multiplication, and the appearance of mature gametocytes over an extended period of observation. Furthermore, using sporozoites derived from two P. ovale-infected patients, we show that human hepatocytes engrafted in TK-NOG mice sustain maturation of the liver stages, and the presence of late-developing schizonts indicate the eventual activation of quiescent parasites. Thus, TK-NOG mice are highly suited for in vivo observations on the Plasmodium species of humans.

Mice engrafted with human cells are useful models for research on human malaria parasites. Here the authors show that the complete life cycle of Plasmodium falciparum and the liver stages of Plasmodium ovale can be studied in mice doubly engrafted with human primary hepatocytes and red blood cells.

Association of adipose tissue and liver fibrosis with tissue stiffness in morbid obesity: links with diabetes and BMI loss after gastric bypass

CONTEXT

Liver and white adipose tissue (WAT) develop inflammation and fibrosis.

OBJECTIVE

The aim of the study was to evaluate the bioclinical relevance of WAT fibrosis in morbid obesity and diabetes and the relationships with tissue stiffness measured using a novel device.

DESIGN AND SETTING

Observational and longitudinal studies were conducted in a hospital nutrition department.

PATIENTS

Biopsies of liver and subcutaneous WAT (scWAT) and omental adipose tissue were collected from 404 obese bariatric surgery candidates, of whom 243 were clinically characterized before surgery and 3, 6, and 12 months after surgery. In 123 subjects, liver and scWAT stiffness was assessed noninvasively using vibration-controlled transient elastography (VCTE).

INTERVENTIONS

Bariatric surgery was performed for some patients.

MAIN OUTCOME MEASURE

Adipose tissue fibrosis and stiffness and their link to obesity phenotypes were measured.

RESULTS

scWAT fibrosis was positively associated with liver fibrosis (fibrosis score ≥2) (ϱ= 0.14; P = .01). VCTE-evaluated liver and scWAT stiffness was positively correlated with immunohistochemistry-determined liver (ϱ= 0.46; P = .0009) and scWAT fibrosis (ϱ= 0.48; P = .0001). VCTE-evaluated scWAT stiffness measures negatively associated with dual-energy x-ray absorptiometry-evaluated body fat mass (R = -0.25; P = .009) and were correlated with metabolic variables. Diabetic subjects showed increased scWAT stiffness. Participants less responsive to gastric bypass were older and more frequently diabetic, and they had increased body mass index, serum IL-6, and scWAT and liver fibrosis. Subjects with no diabetes and normal liver had higher fat mass and lower tissue fibrosis and stiffness.

CONCLUSION

scWAT stiffness was associated with tissue fibrosis, obesity, and diabetes-related traits. Noninvasive evaluation of scWAT stiffness might be useful in clinical practice.

Mitosis detection in breast cancer histological images An ICPR 2012 contest

INTRODUCTION

In the framework of the Cognitive Microscope (MICO) project, we have set up a contest about mitosis detection in images of H and E stained slides of breast cancer for the conference ICPR 2012. Mitotic count is an important parameter for the prognosis of breast cancer. However, mitosis detection in digital histopathology is a challenging problem that needs a deeper study. Indeed, mitosis detection is difficult because mitosis are small objects with a large variety of shapes, and they can thus be easily confused with some other objects or artefacts present in the image. We added a further dimension to the contest by using two different slide scanners having different resolutions and producing red-green-blue (RGB) images, and a multi-spectral microscope producing images in 10 different spectral bands and 17 layers Z-stack. 17 teams participated in the study and the best team achieved a recall rate of 0.7 and precision of 0.89.

CONTEXT

Several studies on automatic tools to process digitized slides have been reported focusing mainly on nuclei or tubule detection. Mitosis detection is a challenging problem that has not yet been addressed well in the literature.

AIMS

Mitotic count is an important parameter in breast cancer grading as it gives an evaluation of the aggressiveness of the tumor. However, consistency, reproducibility and agreement on mitotic count for the same slide can vary largely among pathologists. An automatic tool for this task may help for reaching a better consistency, and at the same time reducing the burden of this demanding task for the pathologists.

SUBJECTS AND METHODS

Professor Frιdιrique Capron team of the pathology department at Pitiι-Salpκtriθre Hospital in Paris, France, has selected a set of five slides of breast cancer. The slides are stained with H and E. They have been scanned by three different equipments: Aperio ScanScope XT slide scanner, Hamamatsu NanoZoomer 2.0-HT slide scanner and 10 bands multispectral microscope. The data set is made up of 50 high power fields (HPF) coming from 5 different slides scanned at ×40 magnification. There are 10 HPFs/slide. The pathologist has annotated all the mitotic cells manually. A HPF has a size of 512 μm × 512 μm (that is an area of 0.262 mm (2) , which is a surface equivalent to that of a microscope field diameter of 0.58 mm. These 50 HPFs contain a total of 326 mitotic cells on images of both scanners, and 322 mitotic cells on the multispectral microscope.

RESULTS

Up to 129 teams have registered to the contest. However, only 17 teams submitted their detection of mitotic cells. The performance of the best team is very promising, with F-measure as high as 0.78. However, the database we provided is by far too small for a good assessment of reliability and robustness of the proposed algorithms.

CONCLUSIONS

Mitotic count is an important criterion in the grading of many types of cancers, however, very little research has been made on automatic mitotic cell detection, mainly because of a lack of available data. A main objective of this contest was to propose a database of mitotic cells on digitized breast cancer histopathology slides to initiate works on automated mitotic cell detection. In the future, we would like to extend this database to have much more images from different patients and also for different types of cancers. In addition, mitotic cells should be annotated by several pathologists to reflect the partial agreement among them.

Automated mitosis detection using texture, SIFT features and HMAX biologically inspired approach

CONTEXT

According to Nottingham grading system, mitosis count in breast cancer histopathology is one of three components required for cancer grading and prognosis. Manual counting of mitosis is tedious and subject to considerable inter- and intra-reader variations.

AIMS

The aim is to investigate the various texture features and Hierarchical Model and X (HMAX) biologically inspired approach for mitosis detection using machine-learning techniques.

MATERIALS AND METHODS

We propose an approach that assists pathologists in automated mitosis detection and counting. The proposed method, which is based on the most favorable texture features combination, examines the separability between different channels of color space. Blue-ratio channel provides more discriminative information for mitosis detection in histopathological images. Co-occurrence features, run-length features, and Scale-invariant feature transform (SIFT) features were extracted and used in the classification of mitosis. Finally, a classification is performed to put the candidate patch either in the mitosis class or in the non-mitosis class. Three different classifiers have been evaluated: Decision tree, linear kernel Support Vector Machine (SVM), and non-linear kernel SVM. We also evaluate the performance of the proposed framework using the modified biologically inspired model of HMAX and compare the results with other feature extraction methods such as dense SIFT.

RESULTS

The proposed method has been tested on Mitosis detection in breast cancer histological images (MITOS) dataset provided for an International Conference on Pattern Recognition (ICPR) 2012 contest. The proposed framework achieved 76% recall, 75% precision and 76% F-measure.

CONCLUSIONS

Different frameworks for classification have been evaluated for mitosis detection. In future work, instead of regions, we intend to compute features on the results of mitosis contour segmentation and use them to improve detection and classification rate.

[Whole slide imaging technology: from digitization to online applications]

As e-health becomes essential to modern care, whole slide images (virtual slides) are now an important clinical, teaching and research tool in pathology. Virtual microscopy consists of digitizing a glass slide by acquiring hundreds of tiles of regions of interest at different zoom levels and assembling them into a structured file. This gigapixel image can then be remotely viewed over a terminal, exactly the way pathologists use a microscope. In this article, we will first describe the key elements of this technology, from the acquisition, using a scanner or a motorized microscope, to the broadcasting of virtual slides through a local or distant viewer over an intranet or Internet connection. As virtual slides are now commonly used in virtual classrooms, clinical data and research databases, we will highlight the main issues regarding its uses in modern pathology. Emphasis will be made on quality assurance policies, standardization and scaling.

Relative performances of FibroTest, Fibroscan, and biopsy for the assessment of the stage of liver fibrosis in patients with chronic hepatitis C: a step toward the truth in the absence of a gold standard

BACKGROUND & AIMS

Liver fibrosis stage is traditionally assessed with biopsy, an imperfect gold standard. Two widely used techniques, FibroTest®, and liver stiffness measurement (LSM) using Fibroscan® have been validated using biopsy, and therefore the true performances of these estimates are still unknown in the absence of a perfect reference. The aim was to assess the relative accuracy of FibroTest, LSM, and biopsy using methods without gold standard in patients with chronic hepatitis C (CHC) and controls.

METHODS

A total of 1289 patients with CHC and 604 healthy volunteers, with assessment of fibrosis stage by the three techniques, and alanine aminotransferase (ALT) taken as a control test, were analyzed by latent class method with random effects. In the volunteers, the false positive risk of biopsy was obtained from a large surgical sample of four normal livers.

RESULTS

The latent class model with random effects permitted to conciliate the observed data and estimates of test performances. For advanced fibrosis, the specificity/sensitivity was for FibroTest 0.93/0.70, LSM 0.96/0.45, ALT 0.79/0.78 and biopsy 0.67/0.63, and for cirrhosis FibroTest 0.87/0.41, LSM 0.93/0.39, ALT 0.78/0.08 and biopsy 0.95/0.51. The analysis of the discordances between pairs suggested that the variability of the model was mainly related to the discordances between biopsy and LSM (residuals>10; p<0.0001).

CONCLUSIONS

A method without the use of a gold standard confirmed the accuracy of FibroTest and Fibroscan for the diagnosis of advanced fibrosis and cirrhosis in patients with chronic hepatitis C. The variability of the model was mostly due to the discordances between Fibroscan and biopsy.

Antagonistic regulation of macrophage phenotype by M-CSF and GM-CSF: implication in atherosclerosis

OBJECTIVES

We characterized the transcriptional profiles of GM-CSF- (GM-MØ) and M-CSF-induced macrophages (M-MØ) and investigated in situ a subset of differentially expressed genes in human and mouse atherosclerotic lesions.

METHODS AND RESULTS

Using microarrays we identified a number of genes and biological processes differentially regulated in M-MØ vs GM-MØ. By varying in culture the M-CSF/GM-CSF ratio (0-10), a spectrum of macrophage phenotypes was explored by RT-QPCR. M-CSF (10 ng/ml) stimulated expression of several genes, including selenoprotein-1 (SEPP1), stabilin-1 (STAB1) and CD163 molecule-like-1 (CD163L1) which was inhibited by a low dose of GM-CSF (1 ng/ml); M-CSF inhibited the expression of pro-platelet basic protein (PPBP) induced by GM-CSF. Combining tissue microarrays/quantitative immunohistochemistry of human aortic lesions with RT-QPCR expression data either from human carotids vs mammary non-atherosclerotic arteries or from the apoE null mice normal and atherosclerotic aortas showed that, STAB1, SEPP1 and CD163L1 (M-CSF-sensitive genes) and PPBP (GM-CSF-sensitive gene) were expressed in both human arterial and apoE null mice atherosclerotic tissues.

CONCLUSION

A balance between M-CSF vs GM-CSF defines macrophage functional polarisation and may contribute to the progression of atherosclerosis.

A comparison of the fibrotic potential of nonalcoholic fatty liver disease and chronic hepatitis C

In nonalcoholic fatty liver disease the amount of fibrosis for individual histologic stages is unknown. To better understand the fibrotic potential of nonalcoholic fatty liver disease, we compared the amount of fibrosis in nonalcoholic fatty liver disease versus chronic hepatitis C virus patients. The area of fibrosis for equivalent fibrosis stages was measured by micromorphometry in 70 nonalcoholic fatty liver disease and 70 matched, untreated, chronic hepatitis C virus controls. The area of fibrosis correlated with Brunt stage (r = 0.71; P < .001) in nonalcoholic fatty liver disease and METAVIR stage (r = 0.58; P < .001) in chronic hepatitis C virus. Mean area of fibrosis was similar in nonalcoholic fatty liver disease and chronic hepatitis C virus patients (7.77% versus 7.70%). Although chronic hepatitis C virus patients displayed higher area of fibrosis in early disease (no or mild fibrosis), nonalcoholic fatty liver disease and chronic hepatitis C virus patients had similar area of fibrosis in more advanced disease (7.83% versus 8.06%, respectively; P = .86 for bridging fibrosis; and 16.62% versus 12.98%, respectively; P = .29 for cirrhosis). The area of fibrosis was similar in Brunt stage 3 nonalcoholic fatty liver disease and METAVIR stage 2 chronic hepatitis C virus, the usual threshold for initiating therapy. The area of steatosis declined with increasing fibrosis stages confirming the early loss of liver fat with progressive fibrosis in nonalcoholic fatty liver disease. Fibrosis is as abundant in nonalcoholic fatty liver disease as in chronic hepatitis C virus, especially in the advanced stages of the disease. The fibrotic potential of nonalcoholic fatty liver disease is as severe as that of chronic hepatitis C virus.

An unusual clinical presentation of a rare tumor of the thyroid gland: report on one case of leiomyosarcoma and review of literature

Primary muscle tumors of the thyroid gland are exceedingly rare. We report on the case of a patient with primary leiomyosarcoma of the thyroid gland and review the literature. An 83-year-old woman complaining of neuropathic pain in her left arm and enlargement of her anterior neck underwent multiple surgical biopsies of the thyroid gland. The tumor was composed of interlacing fascicles of spindle-shaped cells that expressed smooth muscle actin and vimentin but were negative for cytokeratins and thyroglobulin. Ultrastructurally, bundles of myofilaments were present. Magnetic resonance imaging showed a thyroid tumor that directly extended to the adjacent vertebra with an associated pachymeningitis. The patient died 2 months after surgery. The diagnosis of primary leiomyosarcoma of the thyroid gland is difficult and requires numerous clinical, radiologic, and pathologic data. To our knowledge, this case is the first one with such a locoregional extension.

Atherogenic properties of LDL particles modified by human group X secreted phospholipase A2 on human endothelial cell function

Increasing evidence suggests that secreted phospholipases A2 (sPLA2s) play an important role in the pathophysiology of atherosclerosis. Among sPLA2s, the human group X (hGX) enzyme has the highest catalytic activity toward phosphatidylcholine, one of the major phospholipid species of cell membranes and low-density lipoprotein (LDL). Our study examined the presence of hGX sPLA2 in human atherosclerotic lesions and investigated the ability of hGX modified LDL to alter human endothelial cell (HUVEC) function. Our results show that hGX sPLA2 is present in human atherosclerotic lesions and that the hydrolysis of LDL by hGX sPLA2 results in a modified particle that induces lipid accumulation in human monocyte-derived macrophages. Acting on endothelial cells, hGX-modified LDL activates the MAP kinase pathway, which leads to increased arachidonic acid release, increased expression of adhesion molecules on the surface of HUVEC, and increased adhesion of monocytes to HUVEC monolayers. Together, our data suggest that LDL modified by hGX, rather than hGX itself may have strong proinflammatory and proatherogenic properties, which could play an important role in the propagation of atherosclerosis.

VLDL-induced triglyceride accumulation in human macrophages is mediated by modulation of LPL lipolytic activity in the absence of change in LPL mass

Mixed dyslipidemia of phenotype IIB is characterized by elevated levels of very low density lipoprotein (VLDL)-1 and VLDL-2 subfractions and of low density lipoprotein (LDL), which are associated with premature formation of atherosclerotic plaques, characterized by the presence of lipid-rich macrophage foam cells. Lipoprotein lipase (LPL) is a key factor in mediating macrophage lipid accumulation and foam-cell formation from native VLDL particles. The action of macrophage-derived LPL in the induction of intracellular lipid accumulation from triglyceride-rich lipoprotein (TRL) subfractions (VLDL-1, VLDL-2) is, however, indeterminate, as is the potential role of VLDL-1 and VLDL-2 in modulating macrophage LPL expression. We evaluated the role of LPL in the interaction of type IIB VLDL-1 and VLDL-2 with human macrophages. Both VLDL-1 and VLDL-2 subfractions induced significant accumulation of triglyceride (9.8-fold, P<0.0001, and 4.8-fold, P<0.0001, respectively) and of free cholesterol content (1.4-fold, P<0.001, and 1.2-fold, P=0.02, respectively). Specific inhibition (90%) of the lipolytic activity of endogenous LPL by tetrahydrolipstatin (THL) in the presence of VLDL-1 or VLDL-2 resulted in marked reduction in cellular loading of both triglycerides (-89%, P=0.008, and -89%, P=0.015, respectively) and free cholesterol (-76%, P=0.02, and -55%, P=0.06 respectively). Furthermore, VLDL-1 and VLDL-2 induced marked increase in macrophage-derived LPL enzyme activity (+81%, P=0.002, and +45%, P=0.02), but did not modulate macrophage-derived LPL mRNA and protein expression; consequently, LPL specific activity was significantly increased from 1.6 mU/microg at baseline to 4.1 mU/microg (P=0.01) and 3.1 mU/microg (P=0.05), in the presence of VLDL-1 and VLDL-2, respectively. We conclude that type IIB VLDL-1 and VLDL-2 induce triglyceride accumulation in human monocyte-macrophages primarily via the lipolytic action of LPL, which may involve stabilization and activation of the macrophage-secreted enzyme, rather than via modulation of enzyme production.

Toxic cardiac effects of catecholamines: role of beta-adrenoceptor downregulation

The aim of our study was to analyse the mechanisms underlying cardiac toxicity caused by beta-adrenoceptor stimulation and the relationships with their associated downregulation during heart failure. We used the experimental model of coronary artery ligation-induced myocardial infarction in male Wistar rats. In order to increase beta-adrenergic stimulation, rats were subjected to a 15-day chronic isoprenaline administration (30 microg/kg/h). Isoprenaline administration induced haemodynamic inotropic compensation, almost abolished in vitro inotropic response to isoprenaline on papillary muscle (P<0.005) but promoted fibrosis. Isoprenaline treatment markedly reduced the B(max) of beta(2)-adrenoceptors (by 53% in sham and 44% in infarcted rats) but not that of beta(1)-adrenoceptors. These results suggest that beta(1)-adrenoceptors rather than beta(2)-adrenoceptors underlie the deleterious effects of chronic beta-adrenergic stimulation on cardiac fibrosis and are in agreement with the demonstrated benefit induced in human heart failure by beta(1)-adrenoceptor antagonists.