Giovanni Ricevuti

Increased expression of neutrophil and monocyte adhesion molecules in unstable coronary artery disease.

BackgroundA rapid increase in leukocyte adhesion to endothelial cells is one of the first events in the acute inflammatory response and in the pathogenesis of vascular diseases. A subgroup of cell surface glycoproteins (the CD11/CD18 complex) play a major role in the leukocyte adhesion process; in particular, the CD11b/CD18 receptor can be upregulated severalfold in response to chemotactic factors. The purpose of this study was to assess whether upmodulation of granulocyte and monocyte CD11b/CD18 receptors takes place during the passage of blood through the coronary tree of patients with clinical manifestations of ischemic heart disease. Methods and ResultsThirty-nine patients who underwent diagnostic coronary arteriography were studied. Group 1 (15 patients) had a clinical diagnosis of unstable angina, group 2 (14 patients) had stable exertional angina, and group 3 (10 patients) had atypical chest pain. Simultaneous sampling from the coronary sinus and aorta was obtained before coronary arteriography. Cell surface receptors were detected by direct immunofluorescence evaluated by flow cytofluorimetry using monoclonal antibodies tagged with fluorescent markers. Leukocytes were stained in unseparated blood to avoid in vitro manipulation that could activate phagocytes. Group 1 and 2 patients had significant coronary artery disease (>50%o coronary narrowing in at least one major coronary vessel), whereas group 3 patients had normal coronary arteries. In group 1, granulocytes and monocytes showed a significantly higher expression of the CD11b/CD18 adhesion receptor in the coronary sinus than in the aorta (both P<.01), whereas no difference in CD11b/CD18 expression was seen in groups 2 and 3. ConclusionPatients with unstable angina have an increased expression of granulocyte and monocyte CD11b/CD18 adhesion receptors, indicating that an inflammatory reaction takes place within their coronary tree. Activation of these leukocytes may induce coronary vasoconstriction, favor thrombotic processes, and further activate platelets, thus having potential implications on the pathogenesis of unstable coronary artery disease.

Immunological aspects of chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a specific clinical condition that characterises unexplained disabling fatigue and a combination of non-specific accompanying symptoms for at least 6 months, in the absence of a medical diagnosis that would otherwise explain the clinical presentation. Other common symptoms include headaches, myalgia, arthralgia, and post-exertional malaise; cognitive difficulties, with impaired memory and concentration; unrefreshing sleep; and mood changes. Similar disorders have been described for at least two centuries and have been differently named neurasthenia, post-viral fatigue, myalgic encephalomyelitis and chronic mononucleosis. Recent longitudinal studies suggest that some people affected by chronic fatigue syndrome improve with time but that most remain functionally impaired for several years. The estimated worldwide prevalence of CFS is 0.4-1% and it affects over 800,000 people in the United States and approximately 240,000 patients in the UK. No physical examination signs are specific to CFS and no diagnostic tests identify this syndrome. The pathophysiological mechanism of CFS is unclear. The main hypotheses include altered central nervous system functioning resulting from an abnormal immune response against a common antigen; a neuroendocrine disturbance; cognitive impairment caused by response to infection or other stimuli in sentient people. The current concept is that CFS pathogenesis is a multifactorial condition. Various studies have sought evidence for a disturbance in immunity in people with CFS. An alteration in cytokine profile, a decreased function of natural killer (NK) cells, a presence of autoantibodies and a reduced responses of T cells to mitogens and other specific antigens have been reported. The observed high level of pro-inflammatory cytokines may explain some of the manifestations such as fatigue and flu-like symptoms and influence NK activity. Abnormal activation of the T lymphocyte subsets and a decrease in antibody-dependent cell-mediated cytotoxicity have been described. An increased number of CD8+ cytotoxic T lymphocytes and CD38 and HLA-DR activation markers have been reported, and a decrease in CD11b expression associated with an increased expression of CD28+ T subsets has been observed. This review discusses the immunological aspects of CFS and offers an immunological hypothesis for the disease processes.

Granulocyte activation after coronary angioplasty in humans.

To determine whether percutaneous transluminal coronary angioplasty (PTCA) would lead to neutrophil activation with subsequent discharge of proteolytic enzymes, like elastase, and oxygen free radicals, like superoxide anion, blood samples were taken from the coronary sinus and aorta in 14 patients with stable angina and one-vessel disease who underwent PTCA. Neutrophils were separated by means of the Ficoll-Hypaque system and were stimulated to detect release of elastase and generation of superoxide anion. Plasma levels of elastase were also measured by an immunoenzymatic method. PTCA was successful in all patients. Plasma elastase levels increased significantly at the end of the procedure compared with pre-PTCA values both in the coronary sinus (from 129.2 +/- 16.6 to 286.6 +/- 39.7 micrograms/l, p less than 0.005) and in the aorta (from 117.4 +/- 13.6 to 258.1 +/- 41.3 micrograms/l, p less than 0.005). On the other hand, superoxide anion released in the supernatants after neutrophil stimulation by phorbol-myristate-acetate decreased after PTCA in the coronary sinus (before PTCA, 60.1 +/- 7.1; after PTCA, 40.7 +/- 6.8 nmol 1 x 10(7) granulocytes/ml/15 min, p less than 0.05), whereas a mild but not significant decrease was observed in the aorta (from 58.3 +/- 10.9 to 55.3 +/- 8.6 nmol 1 x 10(7) granulocytes/ml/15 min, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Neutrophil infiltration into human gliomas

Abstract Human gliomas were analysed for the infiltration of neutrophils using immunohistochemistry by staining sections for CD15-positive and myeloperoxidase-positive cells. Over 70% of all glioma samples analysed (n = 105) had significant neutrophil infiltration, but there was a marked and significant correlation between tumour grade and the extent of the neutrophil infiltration. In the low grade tumours only 40–50% had significant infiltration, while in glioblastoma multiforme over 85% of the samples analysed had significant infiltration. Numbers of neutrophils infiltrating glioblastoma multiforme tumours were also greater than in the other tumour groups. Circulating white blood cell counts were elevated above the normal range in all glioma patients, but this elevation was entirely due to increased numbers of circulating neutrophils. Again, the highest numbers of circulating neutrophils were seen in the glioblastoma multiforme patients. These experiments indicate that glioma-derived factors may directly or indirectly affect the number of circulating neutrophils and influence their infiltration into the tumours.

Mitochondrial Alterations, Oxidative Stress and Neuroinflammation in Alzheimer's Disease

Alzheimers disease (AD) is a multifactorial disorder characterized by the progressive deterioration of neuronal networks. The primary cause and sequence of its progression are only partially understood but abnormalities in folding and accumulation of insoluble proteins such as β-amyloid and Tau-protein are both associated with the pathogenesis of AD. Mitochondria play a crucial role in cell survival and death, and changes in mitochondrial structure and/or function are related to many human diseases. Increasing evidence suggests that compromised mitochondrial function contributes to the aging process and thus may increase the risk of AD. Dysfunctional mitochondria contribute to reactive oxygen species which can lead to extensive macromolecule oxidative damage and the progression of amyloid pathology. Oxidative stress and amyloid toxicity leave neurons chemically vulnerable. The mitochondrial toxicity induced by β-amyloid is still not clear but may include numerous mechanisms, such as the increased permeability of mitochondrial membranes, the disruption of calcium homeostasis, the alteration of oxidative phosphorylation with a consequent overproduction of reactive oxygen species. Other mechanisms have been associated with the pathophysiology of AD. Inflammatory changes are observed in AD brain overall, particularly at the amyloid deposits, which are rich in activated microglia. Once stimulated, the microglia release a wide variety of pro-inflammatory mediators including cytokines, complement components and free radicals, all of which potentially contribute to further neuronal dysfunction and eventually death. Clinically, novel approaches to visualize early neuroinflammation in the human brain are needed to improve the monitoring and control of therapeutic strategies that target inflammatory and other pathological mechanisms. Similarly, there is growing interest in developing agents that modulate mitochondrial function.

Clinical and angiographic correlates of leukocyte activation in unstable angina

OBJECTIVES This study sought to evaluate the relation, if any, between clinical and angiographic findings in patients with unstable angina and monocyte and neutrophil CD11b/CD18 receptor density. The expression of HLA-DR molecules on T lymphocytes, an index of activation of these cells, was also investigated. BACKGROUND Although activation of neutrophils and monocytes has recently been shown in unstable angina, no studies have correlated activation indexes with clinical and angiographic features of patients with this clinical condition. METHODS Sixty patients underwent diagnostic coronary arteriography and simultaneous blood sampling from the aorta and coronary sinus before injection of contrast medium. Cell surface receptors were detected by direct immunofluorescence evaluated by flow cytometry using monoclonal antibodies tagged with fluorescent markers. RESULTS In 38 patients with unstable angina, neutrophils and monocytes showed a significantly higher expression of CD11b/CD18 adhesion receptors in coronary sinus than aortic blood (p < 0.0001 and p < 0.001, respectively). When these patients were analyzed according to clinical characteristics or angiographic findings, no difference in CD11b/CD18 receptor expression in coronary sinus blood was found between the various subgroups, except for patients with at least one episode of chest pain at rest within 48 h of coronary arteriography and a higher neutrophil adhesion molecule density than patients who remained asymptomatic (p = 0.04). Lymphocytes in patients with stable and unstable angina showed a similar percent expression of CD2/CD19 and CD3/HLA-DR antigens, with no difference between aortic and coronary sinus blood. CONCLUSION These results in a larger cohort confirm previous data that neutrophil and monocyte CD11b/CD18 adhesion molecules show a higher expression in the coronary sinus blood of patients with unstable angina. Among clinical and angiographic findings in patients with unstable angina, only the occurrence of chest pain within 48 h of coronary angiography was related to significantly higher values of neutrophil fluorescence intensity, suggesting that the degree of neutrophil activation is related to the proximity of rest angina episodes to blood sampling. Finally, our data do not support the concept of systemic or transcardiac lymphocyte activation in unstable angina.

Expression of neutrophil and monocyte CD11B/CD18 adhesion molecules at different sites of the coronary tree in unstable angina pectoris

To assess the site of leukocyte activation in unstable angina, the expression of neutrophil and monocyte CD11B/CD18 adhesion molecules in 26 patients was measured from blood samples taken from the coronary ostium, the coronary sinus, and the coronary artery just distal to the culprit lesion (postobstructive chamber). CD11B/CD18 adhesion molecules detected by direct immunofluorescence evaluated by flow cytometry were significantly higher in the coronary sinus blood than in both the coronary ostium and the postobstructive chamber blood, suggesting that leukocyte activation takes place at the microcirculatory interface with the injured myocardium, probably as the result of short but repeated episodes of myocardial ischemia.

Alzheimer disease and platelets: how’s that relevant

Alzheimer Disease (AD) is the most common neurodegenerative disorder worldwide, and account for 60% to 70% of all cases of progressive cognitive impairment in elderly patients. At the microscopic level distinctive features of AD are neurons and synapses degeneration, together with extensive amounts of senile plaques and neurofibrillars tangles. The degenerative process probably starts 20–30 years before the clinical onset of the disease. Senile plaques are composed of a central core of amyloid β peptide, Aβ, derived from the metabolism of the larger amyloid precursor protein, APP, which is expressed not only in the brain, but even in non neuronal tissues. More than 30 years ago, some studies reported that human platelets express APP and all the enzymatic activities necessary to process this protein through the same pathways described in the brain. Since then a large number of evidence has been accumulated to suggest that platelets may be a good peripheral model to study the metabolism of APP, and the pathophysiology of the onset of AD. In this review, we will summarize the current knowledge on the involvement of platelets in Alzheimer Disease. Although platelets are generally accepted as a suitable model for AD, the current scientific interest on this model is very high, because many concepts still remain debated and controversial. At the same time, however, these still unsolved divergences mirror a difficulty to establish constant parameters to better defined the role of platelets in AD.

CD40 ligand-dependent maturation of human monocyte-derived dendritic cells by activated platelets.

Atherosclerosis is defined as an inflammatory immunological disease that is triggered by platelet activation, endothelial injury and consequent innate and adaptive immune processes. Dendritic cells are critical for the cell-mediated arm of the immune response as they activate naïve T cells after maturation. Platelets play a crucial role in thrombus formation in the injured vessel walls. We investigated the role of resting and thrombin-activated platelets in dendritic cell maturation in vitro using platelets and monocyte-derived dendritic cells from healthy donors. Resting platelet supernatants did not affect maturation, whereas supernatants from thrombin-activated platelets induced dendritic cell maturation as demonstrated by FACS analysis of HLA-DR expression. This effect was inhibited by anti CD40 ligand antibody, but not by aspirin pretreatment of platelets. Supernatants of platelet-dendritic cell co-cultures induced augmented monocyte migration when platelets were activated by thrombin, again reversible by blocking CD40 ligand. These data show that activated platelets trigger dendritic cell maturation independent of cyclooxygenase-derived arachidonic acid metabolites by mechanisms involving CD40 ligand, which is also involved in monocyte chemotactic mediator release from platelets and dendritic cells. The results of this study suggest a role of CD40 ligand from activated platelets in connecting innate and adaptive immunity.

Reevaluation of prognostic significance of symptoms in Hodgkin's disease

The prognostic value—at diagnosis—of fever, sweating and weight loss, which enter the Ann Arbor B category, and of pruritus, whose influence on survival is still debated, were systematically reevaluated in 635 patients with Hodgkins disease, observed between 1972 and 1982. By means of multivariate analysis an intrinsic, more negative prognostic value was demonstrated for each of the following symptoms: fever over 38°C, weight loss more than 10% of body weight in the 6 months before admission, and severe pruritus, which is defined as being generalized, causing multiple excoriations and resisting local and systemic antipruritics. Patients with the mild counterparts of these symptoms, as well as sweats, were found to have a survival rate quite comparable with that of fully asymptomatic patients. A rearrangement of the Ann Arbor B constitutional symptoms which would replace sweats with severe pruritus might be more correct and more suitable for better selecting the patients who require more aggressive therapy.