Search

The effects of a subcutaneous bolus injection of 2 micrograms neurotensin (NT) or neuromedin N (NMN) on the function of the hypothalamo-pituitary-adrenocortical axis were investigated in both normal and cold-stressed rats. The blood concentrations of ACTH, corticosterone (B) and aldosterone (ALDO) were measured by specific radioimmunoassays 1, 2 or 4 h after the neuropeptide administration. Cold stress enhanced plasma levels of ACTH, B and ALDO, and these rises lasted unchanged until 4 h. NT did not affect either basal or stress-stimulated plasma levels of ACTH and B, while it lowered the plasma ALDO concentration at 4 h in normal rats and increased it at 1 h in stressed animals. NMN did not change the basal plasma level of ACTH, but it did markedly raise blood levels of both B and ALDO; on the other hand, in cold-stressed rats NMN strongly depressed ACTH response and decreased B plasma concentration at 2 h, without evoking apparent changes in ALDO response. In light of these findings the following conclusions and hypotheses can be drawn and suggested: (i) NT and NMN, when administered at a relatively high dose, do not affect ACTH release in rats under basal conditions; (ii) NMN, but not NT, is able to prevent cold stress-induced stimulation of ACTH secretion, probably by inhibiting hypothalamic thermoregulatory centers; and (iii) NT and NMN exert direct adrenocortical antisecretagogue and secretagogue effects, respectively, which could explain the evident lack of correlation between the levels of circulating ACTH and the plasma concentrations of the main adrenal steroid hormones in both normal and stressed rats after neuropeptide administration.

Since recent findings have pointed out a key role for reactive oxygen species in kidney diseases, we investigated superoxide anion (O2-) and hydrogen peroxide (H2O2) generation by peripheral blood polymorphonuclear cells (PMN) in 20 patients with primary IgA nephropathy (IgAN). Results provided evidence for a significant enhancement of O2- and H2O2 production in IgAN subjects in comparison to patients affected by hypertensive renal injury and healthy donors. Among the IgAN group, the highest oxidative metabolism was observed in patients with severe histologic lesions. On the other hand, in vitro vitamin and/or trace element supplementation to PMN suspensions led to a down modulation of their oxidative responsiveness. These data were further supported by the assessment of O2- release on a kinetic basis. Nutrient pretreatment was in fact able to antagonize either the IgAN-related shortening of the lag period or the increase of maximum O2- production rate following agonist stimulation. Taken together, these findings indicate that an exaggerated PMN oxidative metabolism occurs in IgAN and suggest a potential role for micronutrients in the modulation of PMN metabolic pathway.

Proton magnetic resonance spectroscopy (1H-MRS) is a non-invasive technique which has proved to be useful for monitoring various brain metabolites (N-acetyl-aspartate, choline, creatine-phosphocreatine, lactate). A total of 18 patients underwent a combined magnetic resonance imaging (MRI)/1H-MRS protocol in order to evaluate the distribution of the metabolites in the various stages of cerebral ischemia. Our results show a marked decrease of N-acetyl-aspartate and a large content of Lactate during the early phases, and a decrease in N-acetyl-aspartate, choline and creatine-phosphocreatine (Cr-PCr) during the chronic phase.

Wistar albino rats were intravenously injected with 1 ml of an oxyphoretic emulsion of perfluorobutyl-furane and killed 3, 7 or 30 days later. Mitochondria isolated from the liver and kidneys of treated rats showed a small decrease in the transmembrane electrical potential and a substantial depression of the rates of both ATP synthesis and ADP-stimulated respiration. These alterations in mitochondrial oxidative phosphorylation appear to be induced by perfluorocarbon and/or tensioactive molecules interacting with hydrophobic cell structures.

The in vitro effects of vitamin E and selenium on either polymorphonuclear cell (PMN)-mediated chemotaxis and phagocytosis or monocyte chemoattractant protein-1 (MCP-1) production in 21 well-nourished elderly donors were evaluated. Results show that, before treatment, old subjects were characterized by a decrease of both PMN functions and cytokine (CK) release. By contrast, in vitro vitamin E and selenium supplementation was able to enhance significantly the depressed PMN activities and MCP-1 synthesis. These findings suggest a role for both nutrients in the modulation of impaired phagocyte responsiveness during senescence.

Conflicting results have been reported on polymorphonuclear (PMN) cell responsiveness during senescence. Consequently, neutrophil absolute numbers and PMN-mediated chemotaxis, phagocytosis, killing and superoxide anion (O2-) generation in healthy aged volunteers divided into different groups according to increasing age criteria, were investigated and evaluated. Data provide evidence that absolute amounts of PMN cells declined in a significant manner in donors over 85 years old only when compared with young subjects. On the contrary, regardless of age, the aged individuals exhibited a significant impairment of PMN chemotactic, phagocytic and killing functional capacities. Finally, formyl-methionyl-leucyl-phenylanaline (FMLP)-triggered O2- release was reduced in all elderly groups, while depression of O2- production was seen in subjects between the age of 86 and 104 years using phorbol 12-myristate 13-acetate (PMA) as agonist. These findings indicate that an imbalance in the PMN cell immune reactivity occurs throughout the senescence process.

The capacity of polymorphonuclear (PMN) cells to release several cytokines stresses the potential immunomodulatory role of these cells. The effects mediated by purified PMN cell suspensions on pokeweed mitogen (PWM)-driven B cell differentiation was investigated. Results showed that the addition of increasing concentrations of resting PMN cells to peripheral blood mononuclear cell (PBMC) cultures gave rise to inhibition of immunoglobulin (Ig) production. At the same time, similar results were obtained using lipopolysaccharide (LPS)-pretreated PMN cells. In contrast, when LPS, at different concentrations, and PMN cells were both added to PBMC cultures an enhancement of IgG or IgM release in comparison with cultures treated with PMN cells only occurred at low PMN cell/PBMC ratios (1:20 and 1:10), which was maximal in the presence of 10 or 100 ng/ml LPS. This effect was probably mediated by LPS-induced monocyte stimulation, since the supplementation of LPS-activated monocyte supernatants to PMN cell/PBMC cocultures led to an Ig synthesis which mimicked that seen in similarly-treated PBMC cultures. These data suggest the occurrence of various in vitro modulatory effects in the interactions between PMN, LPS and lymphocytes in a PWM-induced B cell polyclonal responsiveness system.

Several findings pint out the occurrence of a strict relationship between lipoproteins and immunoresponsiveness. In this regard, in vitro lipoproteins pretreatment of mononuclear cell suspensions leads to an inhibition of Natural Killer (NK) cytotoxicity or T- and B-mediated immune functions. These results have an in vivo counterpart, since an impairment of either T-driven B cell polyclonal differentiation or phagocyte chemotaxis, phagocytosis and killing has been shown in patients with type IIa and type IIb primary hyperlipoproteinaemia. On the contrary, these activities fall within normal range in type IV hyperlipoproteinaemic subjects. To further address the potential role of polymorphonuclear cells (PMN) in atherosclerotic process, in the present report PMN-mediated superoxide anion (O2-) generation, hydrogen peroxide (H2O2) production, beta-glucuronidase and myeloperoxidase release have been assessed in similar groups of patients. Results provide a clearcut evidence for a significant enhancement of oxidative metabolism by either suspended or adherent to plastic PMN in type IIa primary hyperlipoproteinaemia only. These data were further confirmed by the observation that the same cell suspensions exhibit a significant increase of H2O2 generation and/or beta-glucuronidase and myeloperoxidase release. By contrast, PMN metabolic pathway in type IIb and type IV patients mimics that observed in healthy individuals. In the light of the well known increase of serum low-density lipoproteins (LDL) in type IIa primary hyperlipoproteinaemia, these findings suggest that also PMN may play an important role in the development of atherosclerosis. The augmented oxidative responsiveness may, in fact, give rise to LDL oxidation, which is in turn responsible for foam cell generation through an exaggerated uptake of oxidized LDL by macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Tuberculosis (TBC) is characterized by a complex immune response which parallels the clinical course of the disease. In this respect, acquired resistance, delayed hypersensitivity reaction and anergy are the main types of immune reactivity to mycobacterial antigens. In view of the presence of nonspecific and specific immune deficits in TBC patients, a clinical trial was carried out in a group of 20 individuals with active pulmonary TBC by oral administration of acetyl-L-carnitine (ALC). This drug, which has been shown to possess immunomodulating activities, was able to upregulate the T-dependent antibacterial activity in TBC patients after 30 days' treatment, while the same activity decreased in patients receiving placebo only. On the other hand, ALC did not modify serum levels of tumour necrosis factor-alpha, in the same individuals. This cytokine plays a detrimental rather than beneficial role in TBC pathogenesis. In the light of these data, ALC seems to be a powerful immunomodulator in the course of Mycobacterium tuberculosis infection and other mycobacteriosis.

It is well known that patients with insulin-dependent (or type I) diabetes mellitus are at high risk for bacterial infections. Since conflicting results have been reported on non-specific immune responses in type I diabetes, polymorphonuclear cell (PMN)-mediated phagocytosis and superoxide anion (O2-) generation in a group of individuals with well-controlled type I diabetes mellitus were assessed. Results showed that diabetic subjects were characterized by a significant impairment of phagocytic capacity when compared with healthy donors, while O2- release mimicked that seen in controls. Cell pretreatment with beta-hydroxybutyric acid (beta-HB) gave rise to a significant reduction in either phagocytosis or O2- production by PMN from type I diabetic individuals. Finally, beta-HB and glucose mixture supplementation to PMN suspensions did not induce any modification of their functional activities in comparison with those exerted by cells treated with beta-HB only. A disease-related or beta-HB-mediated PMN dysfunction in insulin-dependent diabetes mellitus is indicated.

During the last few years, several observations point out that oxygen-free radicals may play a pivotal role in the development of myocardial ischaemic/reperfusion injury, chronic obstructive pulmonary disease (COPD) and aging. With particular reference to acute myocardial ischaemic syndrome, these compounds may account for reperfusion-mediated ventricular arrhythmias, myocardial stunning and cell death. Such molecules may also be involved in lung damage during the course of COPD. In this regard, polymorphonuclear cell (PMN) recruitment at myocardial and/or lung level play an important role in oxygen-free radical overproduction. Several factors may, in fact, trigger PMN adhesion, respiratory burst and/or lysosomal enzyme release, this leading to a deleterious effect for the host. As far as elderly is concerned, evidence has been provided for a strict relationship between oxygen-free radical generation and metabolic rate. Nevertheless, the occurrence of PMN impaired functions and malnutrition in aged subjects gives rise to an enhanced synthesis of these compounds. All together, these findings outline the toxicity of oxygen-derived radicals and suggest the usefulness of a therapeutical approach to antagonize their effects.

Several studies outline the imbalance of phagocyte functions in chronic obstructive pulmonary disease (COPD). In this regard, here, we have assessed either monocyte- and polymorphonuclear cell (PMN)-mediated chemotactic, phagocytic and killing capacities or PMN-triggered metabolic pathway in a group of COPD patients before and at different times after thymostimulin administration. Before therapy, an increase of O2-generation and a decrease of myeloperoxidase release were found in these individuals when compared to controls. Moreover, a reduction of either PMN-mediated chemotaxis and killing or monocyte chemotactic capacities was observed. By contrast, no differences were seen in terms of beta-glucuronidase release, monocyte-mediated killing and PMN or monocyte phagocytic function. During a one-year monitoring following immunotherapy, O2- production and myeloperoxidase activity fell within normal values, while phagocyte functional capacities were unaffected by such a treatment. Furthermore, COPD subjects exhibited a significant improvement of their clinical status as assessed during a one-year followup. All together, these findings suggest a potential role for thymostimulin in the treatment of COPD patients.

Recent findings have indicated an imbalance of immune responsiveness in primary IgA nephropathy (IgAN). Thus natural killer (NK) cell frequency and NK cytotoxicity were evaluated in fifteen IgAN patients. CD8+, CD11+, CD56+ and CD57+ lymphocyte percentages in IgAN individuals fell within normal values, while a significant decrease of CD16+ cells was observed in the same group of patients. In contrast, NK activity overlapped that seen in controls as assessed by an agarose-single cell cytotoxic assay. To further investigate the discrepancy between CD16+ cell level and NK cytotoxic activity in IgAN, the proportion of CD11+ CD57+, CD56+ CD16+ and CD57+ CD16+ lymphocytes was determined. In spite of the unaffected CD56+ CD16+ cell frequency, IgAN subjects exhibited a significant decrease of CD11+ CD57+ and CD57+ CD16+ lymphocyte percentages in comparison to controls. It is suggested that a redistribution of NK lymphocyte subsets occurs in IgAN. This may have an important role in the impairment of the immunoregulatory network.

The histological appearance of liver and kidneys and the energy metabolism of isolated liver and kidney mitochondria were evaluated in rats 6 months after intravenous administration of 1 ml of a perfluorocompound emulsion. Both liver and kidney specimens showed neither significant histological alteration nor the presence of intracytoplasmic perfluorocompound particles. A substantial depression of the rate of ATP synthesis was observed both in liver and kidney isolated mitochondria (with respect to control mitochondria) although the magnitude of the transmembrane electrical potential was unaltered. The depression of ATP synthesis in mitochondria isolated from perfluorocompound-treated rats appeared then unrelated to the presence of perfluorocompound micelles within the cells, and might result from the interaction of either the perfluorocompound or the emulsifying agent with the mitochondrial ATP synthetase.

There is evidence for an impaired T cell-mediated B cell response during senescence. In thirty aged donors, pokeweed mitogen (PWM)-driven immunoglobulin (Ig) synthesis by B cells co-cultured with autologous enriched CD4+ lymphocytes and low amounts of monocytes, was evaluated. Under such experimental conditions, elderly cultures displayed a reduced IgG and/or IgM production when compared with the younger counterpart. Moreover, interleukin (IL)-2 and/or IL-5 addition to cultures led to an enhancement of Ig release. In contrast, IL-4 supplementation failed to positively modulate B cell differentiation. At the same time, aged cells cultured in the presence of IL-2 + IL-5 exhibited an increased Ig synthesis, while the addition of IL-2 + IL-4 or IL-4 + IL-5 mixtures did not induce any significant effect in comparison with homologous untreated samples. The results suggest a critical role for IL-2, IL-4 and IL-5 in the modulation of T helper cell-driven B cell polyclonal responsiveness in the elderly.

During the last few years, several observations outline that the impaired T lymphocyte proliferative capacity in the elderly is due to a reduced interleukin 2 (IL-2) release. To further investigate the activation process during lectin stimulation, aged peripheral blood mononuclear cells (PBMC) were stimulated with phytohemagglutinin (PHA) and assessed for CD25 (IL-2 receptor) and CD71 (transferrin receptor) expression at different intervals of time. Our results provided evidence for a significant decline of both structure induction, above all in the later phase of culture. Indomethacin (INDO) treatment gave rise to an enhancement of CD71 antigen expression only, while prostaglandin E2 (PGE2) supplementation to culture media further decreased either CD25 or CD71 receptor induction. Interferon (IFN)-alpha and IFN-gamma treatment failed to modulate the frequency of CD25+ and/or CD71+ cells. Finally, the expression of CD71 receptor was increased by deferoxamine supplementation, this suggesting a partial involvement of iron overload in the depressed function. Although further studies are required to evaluate at a molecular level the decreased antigen expression, these findings indicate that several mechanism are involved in the elderly-related decline of T lymphocyte activation structures during lectin stimulation.

Haemophiliacs exhibit a broad range of immune defects. In this regard we have investigated the functional capacity of purified polymorphonuclear (PMN) cell suspensions in a group of Human Immunodeficiency Virus (HIV)+ or HIV- patients. Our results provide evidence for a significant reduction of PMN-mediated chemotactic responsiveness, phagocytosis and killing in haemophiliacs regardless of HIV infection. The depressed response does not reflect a PMN intrinsic dysfunction, since respiratory burst activity and lysosomal enzyme release from haemophilic PMN are unaffected in comparison to healthy donors. Quite interestingly the pretreatment of PMN from normal donors with either HIV+ or HIV- haemophilic sera gives rise to a reduction of PMN activity. Moreover, the suppressive effect is abrogated by serum heat inactivation. Taken together, these findings indicate a role for serum suppressive factors in the imbalance of PMN functional capacity in haemophilia regardless of HIV infection.

The role of bacterial lipopolysaccharides (LPS) has been evaluated for their influence on the human T cell-mediated anti-Salmonella typhi activity. In nonendemic areas for salmonellosis this activity is exerted by CD4+ lymphocytes armed by IgA, whereas in endemic zones besides these cells also CD8+ lymphocytes armed by IgG display an elevated anti bacterial activity. These results suggest that, in endemic regions, continuous antigenic challenge and, in particular, that exerted by lipid A (the active moiety of LPS) may play a role in triggering this activity. In other series of experiments, pretreatment of endemic peripheral blood lymphocytes (PBL) with smooth and rough (Rb and Re) forms of Salmonella LPS leads to the inhibition of antibacterial activity. In this respect, Re-LPS, which contains lipid A covalently linked to the core-chetodeoxyoctonate, gives rise to the maximum of inhibition. Finally, fractionation of PBL by means of S. minnesota R345 (Rb) cytoadherence has led to the conclusion that anti bacterial activity is present in the Rb-unbound population, thus indicating that bacterial adherence to PBL is a distinct phenomenon from natural anti-S. typhi activity. The overall results suggest that lipid A is able to modulate the expression of antibacterial activity exerted by human peripheral blood T cells.