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Biomedical subjects

C Monari

Publications and source records attributed to C Monari.

35 records · Page 2Linked to original sources
PubMed1996

Inhibition of fungicidal activity of polymorphonuclear leukocytes from HIV-infected patients by interleukin (IL)-4 and IL-10.

OBJECTIVE: To investigate the effect of human recombinant interleukin (hrIL)-4 or hrIL-10 on the functional status of polymorphonuclear leukocytes (PMNL) from normal subjects and HIV-infected patients. DESIGN: In an in vitro system we studied the effect of hrIL-4 or hrIL-10 on phagocytosis, fungicidal activity and superoxide anion production by PMNL. METHODS: PMNL were treated in vitro with hrIL-4 or hrIL-10 or their combination for 6 h and then candidacidal activity was evaluated in a colony-forming unit inhibition assay. Superoxide anion generation by PMNL was measured in the presence or absence of preopsonized zymosan or Candida albicans. RESULTS: Treatment in vitro with hrIL-4 or hrIL-10 of PMNL for 6 h was able to impair candidacidal activity of neutrophils in both normal or HIV-infected patients. The inhibitory effect was time- and dose-dependent and was more evident in PMNL from HIV-infected subjects, and reflected in these latter cells a decrease of superoxide anion generation. The impairment of candidacidal activity in PMNL from HIV-infected patients was accompanied by survival of the yeasts shown by budding formation into phagosomic organelles of cytokine-treated PMNL. CONCLUSIONS: Our data highlight new biological effects of IL-4 and IL-10 evidenced by suppressed effector function of neutrophils; this phenomenon is emphasized in HIV-infected patients suggesting a role for these cytokines in mediating increased susceptibility to microbial infection during AIDS progression.

Adult↗
PubMed1996

Purified capsular polysaccharide of Cryptococcus neoformans induces interleukin-10 secretion by human monocytes.

In this study, we demonstrated that purified capsular polysaccharide of Cryptococcus neoformans is a potent inducer of interleukin-10 (IL-10) secretion by human monocytes. Endogenous IL-10 was involved in regulating tumor necrosis factor alpha and IL-1beta secretion by human monocytes in response to encapsulated C. neoformans strains. Our results suggest a new immunosuppressive effect exerted by glucuronoxylomannan through the induction of IL-10, a potent downregulator of proinflammatory cytokines.

Anti-Bacterial Agents↗
PubMed1996

Capsular polysaccharide of Cryptococcus neoformans induces proinflammatory cytokine release by human neutrophils.

Human polymorphonuclear leukocytes from normal subjects produced proinflammatory cytokines in response to stimulation with Cryptococcus neoformans yeast cells. The cytokines released after stimulation of neutrophils included interleukin-1beta (IL-1beta), IL-6, IL-8 and tumor necrosis factor alpha. The magnitude of the cytokine response was related to the yeast capsule size. Cells of a large-capsule isolate stimulated release of greater amounts of cytokine than did a thinly encapsulated isolate, which, in turn, stimulated release of greater amounts of cytokine than an acapsular isolate. Cytokine release was also stimulated by supernatant fluids from cryptococcal cells that were preincubated with 10% human serum, suggesting the generation of a soluble mediator. The major capsular polysaccharide, glucuronoxylomannan, stimulated release of tumor necrosis factor alpha, IL-1beta, and IL-8 in a dose-dependent fashion. These results differ from previous studies of cytokine secretion by human monocytes in several important respects, including the importance of encapsulation in stimulation of cytokine secretion and the ability of purified glucuronoxylomannan to induce cytokine secretion.

Cryptococcus neoformans↗
PubMed1995

Beneficial effect of recombinant human granulocyte colony-stimulating factor on fungicidal activity of polymorphonuclear leukocytes from patients with AIDS.

The effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) administration on the functional status of polymorphonuclear leukocytes (PMNL) in neutropenic AIDS patients was investigated. PMNL destructive activity against Candida albicans or encapsulated or acapsular Cryptococcus neoformans was significantly impaired with respect to control subjects before rhG-CSF treatment. After subcutaneous administration of rhG-CSF (5 micrograms/kg), neutrophil counts increased 3- to 11-fold in 24 h and returned to baseline within 96 h. PMNL fungicidal activity showed significant enhancement 48-72 h after rhG-CSF administration that decreased to baseline within 96 h. Enhanced rhG-CSF-mediated destructive activity strictly correlated with augmented superoxide anion production by PMNL. These findings suggest that therapeutic use of rhG-CSF at appropriate schedules in neutropenic AIDS patients could decrease the risk of infection or, in association with antibiotic therapy, more rapidly resolve the occurring infections.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Downregulation by cryptococcal polysaccharide of tumor necrosis factor alpha and interleukin-1 beta secretion from human monocytes.

The regulation by Cryptococcus neoformans encapsulation of interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) production by human monocytes was investigated. By using encapsulated and acapsular C. neoformans, we demonstrated that both strains induce cytokine production, although the acapsular strain was a better stimulator than the thinly encapsulated strain. The cytokine levels produced by cells stimulated by the two strains were lower and followed a different kinetic than those stimulated by lipopolysaccharide (LPS). Purified capsular polysaccharide inhibits TNF-alpha secretion induced by LPS or acapsular C. neoformans. In contrast, no regulator effect on IL-1 beta was observed when LPS was used. The secretory response of these cytokines follows different pathways of macrophage activation; in fact, complete inhibition of TNF-alpha does not affect IL-1 beta production and vice versa. These data indicate that purified capsular polysaccharide of C. neoformans could contribute to the in vivo progress of cryptococcosis by suppressing cytokine production of macrophages and suggest that a therapeutic approach to address the suppressive effect of cryptococal polysaccharide could be devised.

Adult↗
PubMed1994

Cytokine regulation of low-affinity IgE receptor (CD23) on monocytes from asthmatic subjects.

The regulation of CD23 expression (Fc epsilon RII) by cytokines on monocytes from normal subjects, asymptomatic and acute asthmatics was investigated. CD23 was weakly expressed on cells from controls, but was significantly enhanced in the two groups of asthmatics. The addition of IL-4 on monocytes induced an increase of CD23 expression in cells from controls and asthmatics. Interferon-gamma (IFN-gamma) did not modulate CD23 expression in asthmatics or control subjects, while high doses of IL-6 (2000 U/ml) enhanced CD23 expression on cells from asthmatics or controls. In vitro stimulation of monocytes with Timothy grass pollen allergen did not enhance CD23 receptor in asthmatics with a positive skin test to this pollen. We speculate that CD23 expression in asthmatics is markedly enhanced by Th2-dependent cytokines, such as IL-4 and IL-6. Thus, the regulation of Th2 cell activation by anti-cytokine therapy could have an important effect on the down-regulation of CD23 on monocytes, and in shifting a Th2 subpopulation into a Th1 subpopulation by blocking Th2-dependent cytokines.

Adolescent↗
PubMed1994

Encapsulation of Cryptococcus neoformans regulates fungicidal activity and the antigen presentation process in human alveolar macrophages.

Our previous studies have shown that unstimulated alveolar macrophages (AM) play a predominant role as antigen-presenting cells in Cryptococcus neoformans infections, while the function as effector cells seems to be of minor relevance. The present study focuses on the role of encapsulation of C. neoformans on fungicidal activity and the antigen presentation process of AM. Fungicidal activity in unstimulated AM occurs to a higher degree when the acapsular strain is employed, but this is impaired compared with other natural effectors, such as peripheral blood monocytes (PBM) and polymorphonuclear (PMN) cells. Cryptococcus-laden AM also induce a higher proliferative response in autologous CD4+ lymphocytes when the acapsular strain is used compared with encapsulated yeast. The enhanced blastogenic response is, in part, ascribed to an augmented IL-2 production by T cells. In addition, higher levels of interferon-gamma (IFN-gamma), but not IL-4, are produced by the responding T cells, when the acapsular strain is used compared with the encapsulated yeast. Moreover, IFN-gamma is able to induce fungicidal activity in AM against the encapsulated yeast and augments killing activity of the acapsular strain. This phenomenon is not mediated by nitric oxide production, but is correlated with an enhancement of fungicidal activity of cytoplasmic cationic proteases. We speculate that encapsulation of C. neoformans could down-regulate the development of the immune response mediated by Cryptococcus-laden AM at lung level.

Adult↗
PubMed1994

Role of human alveolar macrophages as antigen-presenting cells in Cryptococcus neoformans infection.

The contribution of human alveolar macrophages (AM) from normal subjects in Cryptococcus neoformans infection was investigated. AM were able to efficiently phagocytize the fungus after opsonization, but killing activity did not occur at an effector-to-target ratio of 10:1 in a 6-h incubation since there was an inhibition of phagosome-lysosome fusion. Moreover, the role of AM as antigen-presenting cells was investigated. Cryptococcus-laden AM were co-cultured with autologous T lymphocytes and lymphoproliferation was determined; a massive blastogenic response of alpha/beta TCR-bearing T lymphocytes was observed. The response started after 1 day of co-culture and was triggered and regulated by IL-1 produced by AM in response to C. neoformans. Finally, the antigen-presentation process was associated with HLA class II DR molecules. This finding suggests that AM play a key role in the lung as antigen-presenting cells and, through the secretion of IL-1, regulate proliferation and activation of T lymphocytes, which are important in mediating pulmonary clearance. We speculate that in immunodepressive conditions, the impairment of AM functions could contribute to the spread of C. neoformans infection from the lung.

Adult↗
PubMed1980

[The genetic incidence on QT interval values in ECG (author's transl)].

On the grounds of the well-known finding of the familial incidence of the elongated QT interval in various conditions, a research has been carried on in order to point out the possible genetic conditioning of this electrocardiographic pattern. From the analysis of the QTc values in the components of 28 families of carriers of "labile pseudo-ischemic T wave" it comes out that the QTc phenomenon is conditioned by the heredity. The distribution of the aplotypes HLA does not permit to settle any correlation with these genetic markers on account of the restricted number of the examined cases.

Adult↗
PubMedDate not supplied

Continuous measurement of vascular access recirculation by conductivity.

Vascular access recirculation is one of the main factors influencing dialysis efficiency. The underestimation of or mistakes in the measurement of access recirculation causes a discrepancy between dialysis prescription and the actual dose of dialysis administered. Moreover, access recirculation is known to increase during a dialysis session. Therefore, the evaluation of recirculation is necessary to correctly prescribe dialysis and the ideal measurement method should be very accurate and feasible at any moment during a dialysis session.

Blood Flow Velocity↗