Stefania Greco

Neurotrophin and neurotrophin receptor expression in alveolar macrophages: an immunocytochemical study.

Abstract Alveolar macrophages play a crucial role in regulating lung immune responses and in maintaining the integrity of the respiratory tract. Neurotrophins (NTs), besides to their neurotrophic activities, exhibit physiological effects in the immune system. In this study, nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), NT-3 and low- (p75) and high affinity (Trks) NT receptors were investigated by immunocytochemistry in cytospin centrifuged preparations of human alveolar macrophages. Approximately 2.5% alveolar macrophages were immunoreactive for NGF, whereas no macrophages displaying immunoreactivity for BDNF or NT-3 were observed. A 3.5% macrophages displayed immunoreactivity for TrkA-receptor protein, 10% for TrkB-receptor protein (full length isoform), and 2% for TrkC-receptor protein. No low-affinity p75 NT and TrkB[-] truncated isoform receptor immunoreactive macrophages were found. These findings support the hypothesis that NTs and the corresponding receptors may play a role in regulating immunological and functional activity of alveolar macrophages via paracrine/autocrine mechanisms.

Labeling of dopamine D3 and D4 receptor subtypes in human peripheral blood lymphocytes with [3H]7-OH-DPAT: a combined radioligand binding assay and immunochemical study

Molecular biology studies have demonstrated that human peripheral blood lymphocytes express dopamine D2-like receptors belonging to the D3 and D4 receptor subtypes, whereas the characterization of these receptors using radioligand binding assay techniques provided conflicting results. The preferential dopamine D3 receptor agonist [3H]7-hydroxy-N, N-di-n-propyl-2-aminotetralin ([3H]7-OH-DPAT) was used recently for labeling lymphocyte dopamine D3 receptor. However, the selectivity of this compound for the D3 receptor was questioned. In this study we have investigated human peripheral blood lymphocyte dopamine receptor subtypes labeled by [3H]7-OH-DPAT using a conventional radioligand binding assay technique and antibodies against dopamine D2-like receptor subtypes. [3H]7-OH-DPAT was specifically bound to intact human peripheral blood lymphocytes with a dissociation constant (Kd) value of 0.32 + 0.03 nM and a maximum density of binding sites (Bmax) of 18.2 + 0.8 fmol/2 x 10(6) cells. [3H]7-OH-DPAT binding was unaffected by antibodies against dopamine D2 and D2S receptors. Anti-dopamine D3 and D4 receptor antibodies reduced [3H]7-OH-DPAT binding by about 53% and 32% respectively. Combination of anti D3 and D4 receptor antibodies reduced remarkably [3H]7-OH-DPAT binding. The above results suggest that the dopamine receptor agonist [3H]7-OH-DPAT labels dopamine D3 and D4 receptor subtypes in human peripheral blood lymphocytes. The use of antibodies raised against dopamine receptor subtypes in combination with radioligand binding assay may contribute to define receptor subtypes expressed by human peripheral blood lymphocytes in health and disease.

α1-Adrenergic Receptor Subtypes in Human Peripheral Blood Lymphocytes

We investigated the expression of alpha1-adrenergic receptor subtypes in intact human peripheral blood lymphocytes using reverse transcription-polymerase chain reaction (RT-PCR) and radioligand binding assay techniques combined with antibodies against the three subtypes of alpha1-adrenergic receptors (alpha1A, alpha1B, and alpha1D). RT-PCR amplified in peripheral blood lymphocytes a 348-bp alpha1A-adrenergic receptor fragment, a 689-bp alpha1B-adrenergic receptor fragment, and a 540-bp alpha1D-adrenergic receptor fragment. Radioligand binding assay with [3H]prazosin as radioligand revealed a high-affinity binding with a dissociation constant value of 0. 65+/-0.05 nmol/L and a maximum density of binding sites of 175. 3+/-20.5 fmol/10(6) cells. The pharmacological profile of [3H]prazosin binding to human peripheral blood lymphocytes was consistent with the labeling of alpha1-adrenergic receptors. Antibodies against alpha1A-, alpha1B-, and alpha1D-receptor subtypes decreased [3H]prazosin binding to a different extent. This indicates that human peripheral blood lymphocytes express the three alpha1-adrenergic receptor subtypes. Of the three different alpha1-adrenergic receptor subtypes, the alpha1B is the most represented and the alpha1D, the least. Future studies should clarify the functional relevance of alpha1-adrenergic receptors expressed by peripheral blood lymphocytes. The identification of these sites may represent a step for evaluating whether they represent a marker of alpha1-adrenergic receptors in cardiovascular disorders or for assessing responses to drug treatment on these receptors.

Neurotrophins and Neurotrophin Receptors in Human Pulmonary Arteries

The localization of neurotrophins (NTs) and NT receptors was analyzed in sections of human extra- and intrapulmonary arteries by Western blot analysis and immunohistochemistry. In extrapulmonary branches of human pulmonary artery, NT and NT receptor immunoreactivity was located in the tunica intima, within endothelium, in the tunica media, within smooth muscle and in the tunica adventitia. In different sized intrapulmonary arteries, NT and NT receptor immunoreactivity was observed primarily in the tunica adventitia. A faint NT and NT receptor immunoreactivity was observed in the tunica media of large-sized branches of intrapulmonary arteries, but not within medium- or small-sized intrapulmonary vessels or in tunica intima of different sized intrapulmonary arteries. These findings suggest that NTs may have a role in the control of vascular responses in the pulmonary system acting as local paracrine or autocrine mediators. The possible relevance of the NT system in human pulmonary vasculature identified in this study is discussed.

Expression of dopamine receptors in immune organs and circulating immune cells.

The existence of dopamine (DA) D1- and D2-like receptors in the rat and pigeon thymus and in human peripheral blood lymphocytes was investigated. The selective D1-like antagonist [3H]-SCH 23390 was used as a ligand of DA D1-like receptors (D1 and D5 sites). Pharmacological analysis suggests that binding of [3H]-SCH 23390 to sections of thymus and to human peripheral blood lymphocytes belongs mainly to the dopamine D5 receptor subtype. Light microscope autoradiography, performed in sections of rat and pigeon thymus, revealed that these receptors are located primarily in the cortical layer. DA D2-like receptors (D2, D3 and D4 sites) were studied in sections of rat thymus and in peripheral blood lymphocytes by using the putative DA D3 receptor agonist [3H]-7-OH-DPAT as a ligand. Both rat and pigeon thymus and human peripheral blood lymphocytes express a putative DA D3 receptor. These data are in agreement with recent molecular biology studies performed in human peripheral blood lymphocytes. The demonstration of different subtypes of DA receptors in a primary immune organ such as the thymus and in circulating immune cells supports the hypothesis of an involvement of DA in the control of immune function.

Influence of age on L-type Ca2+ channels in the pulmonary artery and vein of spontaneously hypertensive rats.

The influence of age on the density and localization of L-type Ca2+ channels was studied during development of hypertension in the pulmonary artery and vein of spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) rats by radioligand binding assay and light microscope autoradiography. SHR were examined at 6 weeks (juvenile, pre-hypertensive stage), 12 weeks (young, developing hypertension) and 24 weeks (mature, established hypertension). The dihydropyridine-type Ca2+ antagonist [3H]nicardipine was used as a radioligand. It was bound specifically to sections of rat pulmonary artery and vein. Dissociation constant (Kd) values were similar in WKY rats and SHR, whereas maximum density of binding sites (Bmax) values increased in SHR in comparison with WKY rats. This increase was noticeable from the pre-hypertensive phase. The pharmacological profile of [3H]nicardipine binding was similar in different age groups of either normotensive and hypertensive rats. Quantitative analysis of autoradiographs from SHR revealed a progressive increase of silver grains in smooth muscle of tunica media and to a lesser extent in the adventitia of pulmonary artery but not of pulmonary vein from pre-hypertensive stage to developing hypertension. No further changes were observed in established hypertension. The above data indicate that the density of L-type Ca2+ channels of pulmonary arteries is increased in SHR. This augmentation after the pre-hypertensive phase suggests the occurrence of dysregulation of Ca2+ handling in the pulmonary vasculature of developing SHR.

Evaluation of response to chemotherapy in patients affected with non-small cell lung cancer by means of three tumour markers elaborated by discriminant analysis.

Chemotherapy is the most effective treatment for inoperable patients (70%) affected with non-small cell lung cancer (NSCLC). The early detection of tumour progression is mandative in order to promptly shift these patients towards salvage or supportive therapy. The present authors investigated the clinical value of a panel of tumour markers, elaborated by means of discriminant analysis, as a follow-up indicator for the detection of tumour progression. The serum levels of tissue polypeptide antigen (TPA), CYFRA-21.1, neuron-specific enolase (NSE) and carcino-embryonic antigen (CEA) were determined before chemotherapy and after three cycles of treatment. Discriminant analysis generated a formula (canonic variable) which correctly classified the 87.8% of the 74 subjects (86.1% of the 36 progressive diseases and 89.5% of 38 non-progressive diseases). This approach produces an algorithm able to calculate a progression score in NSCLC patients which can be helpful for following-up care and therapy control of these patients.

Age-related changes of the noradrenergic innervation of rat tracheo-bronchial tree and pulmonary vasculature.

Age-related changes of the noradrenergic innervation of the tracheo-bronchial tree and of pulmonary vasculature were investigated in male Wistar rats of 3 months (young), 12 months (adult) and 24 months (old/aged), using catecholamine histofluorescence techniques associated with image analysis and by high pressure liquid chromagraphy with electrochemical detection. In young rats, blue-green fluorescent nerve fibres supply tracheo-bronchial smooth muscle and tracheal and bronchial glands, which are innervated by a delicate network of nerve fibres rich in varicosities. Pulmonary artery and vein are sparsely innervated. They are supplied with nerve fibres distributed in the vasa vasorum or the adventitia and the outer tunica media. The higher noradrenaline concentrations were found in the trachea and extraparenchymal bronchi, followed by pulmonary vein and pulmonary artery. The density and pattern of noradrenergic innervation of the tracheo-bronchial tree, or of the pulmonary vasculature, were similar in young and adult rats. In aged rats, a loss of noradrenergic innervation involving primarily the supply to the smooth muscle of the tracheo-bronchial tree was observed. Histofluorescence techniques demonstrated a higher sensitivity than noradrenaline assay in detecting changes of the sympathetic innervation of the tracheo-bronchial tree and of the pulmonary vasculature. The possible significance of reduced noradrenergic innervation of the tracheo-bronchial tree in aged rats is discussed.

Validation of an algorithm able to differentiate small-cell lung cancer (SCLC) from non-small-cell lung cancer (NSCLC) patients by means of a tumour marker panel: analysis of the errors.

By means of a mathematical score previously generated by discriminant analysis on 90 lung cancer patients, a new and larger group of 261 subjects [209 with non-small-cell lung cancer (NSCLC) and 52 with small-cell lung cancer (SCLC)] was analysed to confirm the ability of the method to distinguish between these two types of cancers. The score, which included the serum neuron-specific enolase (NSE) and CYFRA-21.1 levels, permitted correct classification of 93% of the patients. When the misclassifications were analysed in detail, the most frequent errors were associated with limited disease SCLC with low NSE levels and with advanced NSCLC with high NSE levels. This demonstrates the importance of the marker in correctly categorizing patients.

Carcinoembryonic antigen, tissue polypeptide antigen and neuron-specific enolase pleural levels used to classify small-cell and non-small-cell lung cancer patients by discriminant analysis

The classification of lung cancer into smallcell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC) is essential for disease prognosis and treatment. For this purpose, we have tried to optimize the use of three tumour markers determined on pleural effusions, to differentiate SCLC from NSCLC by means of a canonic variable, generated by discriminant analysis, including subjects with histologically proven lung cancer. Discriminant analysis was performed by using carcinoembryonic antigen, neuron-specific enolase and tissue polypeptide antigen pleural levels, determined in 65 consecutive and unselected patients, histologically classified as 49 NSCLC and 16 SCLC. To validate the formula generated, a control group of 37 lung cancer patients (10 SCLC and 27 NSCLC), enrolled subsequently, was employed. Applying the discriminant analysis to SCLC and NSCLC patients a good classification was obtained (92% rate of correct classification). The aforementioned formula, applied to the validation group, showed a 92% rate of correct classification. This method, which is rapid, inexpensive and routinely applicable to malignant pleural effusions, may be reliably used to classify lung cancer patients.