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J A Nogueira-Machado

Publications and source records attributed to J A Nogueira-Machado.

At least 19 recordsLinked to original sources
PubMed2006

Modulation of the production of reactive oxygen species (ROS) by cAMP-elevating agents in granulocytes from diabetic patients: an Akt/PKB-dependent phenomenon.

BACKGROUND: Granulocytes from healthy subjects and from patients suffering from diabetes mellitus present differences in reactivity to stimulation with cyclic nucleotide-elevating agents. The production of reactive oxygen species (ROS) is inhibited in cells from non-diabetic subjects following such stimulation, but activated through a PKA-independent signaling pathway in granulocytes from type 1 and type 2 diabetic patients. The aim of the present study was to understand better the changes in signaling mechanisms induced by the disease. METHODS: ROS production in granulocytes from healthy subjects and from type 1 and type 2 diabetic patients was measured using a luminol-dependent chemiluminescence assay. Granulocytes were stimulated by the addition of the cAMP-elevating agent dibutyryl cAMP. In some experiments, granulocytes were pre-treated with an inhibitor of PKA or Akt/PKB prior to cAMP stimulation. RESULTS: Intracellular elevation of cAMP induced a PKA-dependent and Akt/PKB-independent inhibition of ROS production in granulocytes from healthy subjects, but a significant activation in cells from both type 1 and type 2 diabetic patients. Most significantly, activation of ROS generation in cells from diabetic patients was shown to be Akt/PKB-dependent and PKA-independent. CONCLUSIONS: These results suggest that chronic hyperglycaemia could induce metabolic adaptation in cAMP-related signaling mechanisms. Epac (exchange protein directly activated by cAMP) is a novel cAMP receptor besides PKA involved in different signaling pathways. The cAMP-stimulated inverse ROS response in granulocytes from type 1 and type 2 diabetic patients may be due to a change in signaling pathways from cAMP/PKA to cAMP/Epac/Akt/PKB. These preliminary results require further studies in order to evaluate their consequences on innate immunity and pathogenesis of diabetes mellitus.

Adult↗
PubMed2003

Modulation of the reactive oxygen species (ROS) generation mediated by cyclic AMP-elevating agents or Interleukin 10 in granulocytes from type 2 diabetic patients (NIDDM): a PKA-independent phenomenon.

UNLABELLED: SUMMARY-BACKGROUND: The present study investigates the hypothesis that cells from ill patients and from healthy subjects may have different reactivity under metabolic stimulation as a consequence of an disease-induced metabolic adaptation. METHODS: Granulocytes either from healthy subjects or from type II-Non Insulin Dependent Diabetes Mellitus (NIDDM) patients were compared in their capacities to generate Reactive Oxygen Species (ROS). The ROS generation was comparatively determined in a chemiluminescence assay, luminol-dependent, after cell incubation in the presence of either cyclic AMP - elevating agents or Interleukin 10. In some experiments the cells were pretreated with H89 compound (a PKA inhibitor) or with diphenylene iodonium (DPI), a NADPH-oxidase inhibitor. RESULTS: Our results showed an increased ROS generation in granulocytes from diabetic patients in absence of cyclic AMP-elevating agents or IL-10. In the presence of cyclic AMP-elevating agents was observed an inverse metabolic response in granulocytes from diabetic patients in comparison to cells from healthy subjects. The granulocytes were pre-incubated in the presence of cyclic AMP-elevating agents--amminophylline (AMF) or dibutyryl cyclic AMP (dbcAMP)--or interleukin 10 (IL-10). The AMF, dbcAMP and IL-10 inhibited ROS production by granulocytes from healthy subjects. By contrast, AMF and dbcAMP activated cells from diabetic patients while IL-10 had no effect. The inhibition of ROS induced by AMF, dbcAMP or IL-10 was promptly abolished by the pretreatment of the cells with either PKA H89 inhibitor or NADPH-oxidase inhibitor (DPI) in granulocytes from healthy subjects. In relation to the granulocytes from type 2 diabetics patients, the activation of ROS generation mediated by AMF and dbcAMP was fully abolished by NADPH-oxidase DPI-inhibitor, but not by PKA H89 inhibitor. CONCLUSIONS: Our present results reinforce the hypothesis that cells from ill patients (type II diabetic) when compared to cells from healthy subjects have different reactivity under metabolic stimulation. ROS production by human granulocytes was modulated by cyclic AMP elevating agents and IL-10. The inhibition of the ROS production in cells from healthy subjects was PKA-dependent while the activation in granulocytes from patients was PKA-independent. This inverse metabolic response, in cells from patients, suggests the use of an alternative metabolic pathway PKA-independent, possible cAMP/Epac/PKB-dependent. The correlation between activation of ROS production in granulocytes from diabetic patients and pathogenesis of diabetes can be suggested, however, further and extensive studies are needed for demonstrating this suggestion.

Aged↗
PubMed2002

Effect in vitro of cyclic nucleotides-elevating agents on nitric oxide production by human granulocytes from type 2-diabetic patients.

BACKGROUND: The present study was designed to investigate the hypothesis that cells from ill patients and from healthy subjects may have different reactivities under metabolic stimulation. METHODS: The study was performed with granulocytes from non-diabetic subjects and from type II -Non Insulin Dependent Diabetes mellitus (NIDDM) patients. The nitric oxide (NO) generation was comparatively determined by the nitrite concentration (micromolar of nitrite) after cell incubation in the presence of cyclic nucleotide-elevating agents. RESULTS: Our results showed an inverse reactivity for granulocytes from diabetic patients when compared to non-diabetic subjects. Granulocytes were incubated in the presence of drugs that elevate the intracellular level of cyclic AMP aminophylline (AMF), dibutyryl cyclic AMP (dbcAMP)], cyclic GMP [8.Br. cyclic GMP(8.Br.cGMP) or levamisole (LEV)]. The cyclic AMP-elevating agents (AMF and d bcAMP) inhibited NO production by granulocytes from non-diabetic subjects and activated cells from diabetic patients. By contrast, cyclic GMP-elevating agents (8.Br.cGMP and LEV) activated cells from non-diabetic subjects and inhibited granulocytes from diabetic patients. The activation of NO generation by cyclic nucleotides was blocked by pretreatment of granulocytes with L-NAME. CONCLUSION: The authors describe for the first time that both cyclic AMP and cyclic GMP were able to modulate nitric oxide production in human granulocytes and that cell reactivity in ill patients (diabetic) showed altered and inverse response in comparison to granulocytes from healthy subjects. This inverse reactivity possibly reflects a disease-induced adapted metabolic response. The consequences of this altered metabolic response on host defense and inflammation may be speculated, but further experiments are needed to confirm this hypothesis.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2000

Increase of reactive oxygen (ROS) and nitrogen (RNS) species generated by phagocyting granulocytes related to age.

In this present paper the age-induced effect on reactive oxidizing species generated by oxygen (ROS) and nitrogen (RNS) was studied using human phagocyting granulocytes. The ROS and RNS were quantified, respectively, in a chemiluminescence assay and by the measurement of nitrite production. The age-induced reactive oxidizing species generation was studied in healthy subjects ranging from 20 to 80 years old, divided into six age groups: group I, 20-29 years old; group II, 30-39 years old; group III, 40-49 years old; group IV, 50-59 years old; group V, 60-69 years old; and group VI, 70-80 years old. Our results demonstrate a parallelism between generation of the ROS and RNS induced by the age. A significant increase of ROS production was observed from 40 years old (age groups III, IV, V and VI while for RNS this increase was observed only from 50 years old (groups IV, V and VI). These data suggest an increase of oxidizing species generation (ROS/RNS) related to age. The increased generation of ROS (40-49 years old) was induced before the increasing of RNS (50-59 years old) and it may have consequences on inflammation and host defences.

Adult↗
PubMed1999

Comparative study on the effect of cyclic nucleotides related to the function of Biomphalaria glabrata hemocytes and human granulocytes.

The biochemical processes linked up to cyclic nucleotides related to the phenomenon of phagocytosis in Biomphalaria glabrata hemocytes were studied. In hemocytes the results suggest the presence of a phagocytic capacity similar to that observed in human cells related to regulation by cyclic adenylate monophosphate (cAMP), but not by cyclic guanylate monophosphate (cGMP). This similarity and differences in the metabolic process of phagocytary capacity between human phagocytary cells and hemocytes could represent an interesting model aimed at studying the phylogenetic evolution of enzymatic complexes.

Aminophylline↗
PubMed1998

Host defenses in the aged: evaluation of the balance between oxidizing species generation and reducing power in phagocyting human granulocytes.

The respiratory burst reaction has been studied in human granulocytes from normal subjects divided in four age groups: (I) 20-29, (II) 30-39, (III) 40-49, and (IV) 50-59 years old. Zimosan opsonized particles (OZ) were used to evaluate, simultaneously, the reducing power and the oxidizing species generation. Our results showed a strong parallelism and a direct correlation between oxidizing species generation and reducing power in the groups (I) and (II), in presence or in the absence of opsonized zimosan. However, the age groups (III) and (IV) showed an increase in the free radicals generation and a significant decrease in the cellular reducing power. This inverse correlation observed between oxidizing/reducing power in the (III) and (IV) age groups may suggest a metabolic cellular disequilibrium.

Adult↗
PubMed1996

Effect in vitro of gamma interferon and interleukin-10 on generation of oxidizing species by human granulocytes.

We examined the effect of interleukin-10 (IL-10), gamma interferon (IFN-gamma), phorbol ester (PDB), opsonized zymosan (OZ) and aminophylline (a cAMP phosphodiesterase inhibitor) on the reducing power and oxidizing species generation by human neutrophils, using MTT dye reduction and luminol-dependent chemiluminescence assays, respectively. Gamma interferon (IFN-gamma), phorbol ester (PDB) and opsonized zymosan (OZ) were activators while interleukin-10 (IL-10) and aminophylline were inhibitors. A strong parallelism was observed between oxidizing species generation and cellular reducing power in both activation and inhibition experiments. Our results also demonstrate for the first time the effect of IL-10 on free radical generation by neutrophils. The consequence of these activating and inhibiting effects on the inflammatory process are discussed.

Free Radicals↗
PubMed1996

Effect of gamma interferon and interleukin 10 on phosphoinositol turnover by human neutrophils in vitro.

We evaluated the levels of inositolmono-(IP1), di(IP2), tri-(IP3) and tetraphosphates (IP4) in human neutrophils (N) stimulated with gamma interferon (IFN-gamma) (200 microliters from a pool of cell culture supernatant obtained from 1 x 10(7) PHA-primed peripheral blood mononuclear cells (30-60 min at 37 degrees C, 5% CO2)) in the presence of in the absence of interleukin 10 (IL-10) (10 micrograms/10 microliters). The results, reported as mean +/- SEM cpm, showed that IFN-gamma induced a significant increase only in the IP3 level (N + medium = 1,413 +/- 172 and N + IFN-gamma = 8,875 +/- 832). However, this activation mediated by IFN-gamma was blocked partially in the presence of IL-10 (N + IFN-gamma + IL-10 = 2,430 +/- 239) (P < 0.05). Interleukin 10 alone did not induce significant alterations in the content of IP1 (1,203 +/- 123), IP2 (1,880 +/- 163), IP3 (938 +/- 102) or IP4 (2,403 +/- 345) when compared to the respective controls in the absence of IL-10 (IP1 = 1,625 +/- 132; IP2 = 1,343 +/- 149; P3 = 1,413 +/- 172 and IP4 = 3,281 +/- 234). We also demonstrated the inhibitory effect of IL-10 of chemoluminescence generation by human neutrophils during phagocytosis of opsonized particles (OZ). Chemoluminescence generation was enhanced by IFN-gamma (N = OZ = 42.8 +/- 3.9 and N + OZ + IFN-gamma = 66.5 +/- 4.3) and this effect was reduced by IL-10 (N + OZ + IFN-gamma + IL-10 = 37.6 +/- 5.1). These data suggest that IL-10 modulates the neutrophil response and may be important for the development of new treatments of inflammatory injury.

Humans↗
PubMed1994

Chemoluminescence generation and MTT dye reduction by polymorphonuclear leukocytes from periodontal disease patients.

Alterations of polymorphonuclear leukocytes (PMNs) functions have been reported in patients with severe forms of some periodontal disease. In this study we evaluated the chemoluminescence generation and MTT dye reduction by human PMN in patients with juvenile periodontitis (JP), rapidly progressive periodontitis (RPP) and adult periodontitis (AP) during protein kinase C (PKC) activation or during the phagocytosis of opsonized zymosan. The results demonstrated that only PMNs of JP patients showed a decreased chemoluminescence generation and MTT dye reduction during the phagocytosis of opsonized zymosan (p < 0.05). The time to reach the maximal peak during the PKC activation on the chemoluminescence reaction was evaluated and JP PMNs patients demonstrated a depressed value (7.0 +/- 0.4 min) compared with healthy volunteers (13.8 +/- 0.5 min). The etiology and importance of such cellular alterations in the immunopathogenesis of the periodontal disease are discussed.

Adolescent↗
PubMed1993

Human giant cell formation induced in vitro by Schistosoma mansoni antigens.

Although multinucleated giant cells have been described for many years in association with different chronic inflammatory responses, their participation in immunoregulatory mechanisms within the schistosome egg granulomas remains to be clarified. In this study we determined if soluble egg antigen (SEA) or adult worm antigen preparations (SWAP) from S. mansoni induce giant cell formation in vitro and their relationship with the intensity of granulomatous reactivity. Antigenic stimulation of peripheral blood mononuclear cells (PBMC) from patients (N = 9) with active schistosomiasis infection increased giant cell formation per field after the 12th day in culture when treated with S. mansoni SEA conjugated to polyacrylamide beads (PB-SEA) (17 +/- 1.2) and SWAP (PB-SWAP) (18.5 +/- 1.5). The increase in the number of giant cells was statistically significant when compared to the control polyacrylamide beads (PB) (9 +/- 1.1) and purified protein derivative conjugated to beads (PB-PPD) (11.6 +/- 1.7). We also observed a correlation between an increase in the number of giant cells and a decrease in in vitro granuloma index (GI) to PB-SEA (GI decreased from 4.3 +/- 0.2 on the 6th day to 3.2 +/- 0.2 on the 12th day) and PB-SWAP (GI decreased from 4.8 +/- 0.3 on the 6th day to 3.5 +/- 0.05 on the 12th day). These data suggest that giant cell formation may be one of the immunoregulatory mechanisms involved in the down-regulation of the granuloma reaction against S. mansoni eggs.

Animals↗
PubMed1991

Colorimetric leukocyte adherence inhibition assay: a new auxiliary technique for the diagnosis of schistosomiasis.

We describe a modification of the leukocyte adherence inhibition assay (LAI) in which we propose the use of 3-(4,5-dimethylthiazole-2-yl)-2-5-diphenyltetrazolium bromide (MTT) dye which is taken up and reduced by mitochondria. The method was tested by screening peripheral blood leukocytes from Schistosoma mansoni-infected patients. Peripheral blood leukocytes from patients (N = 21) but not from the blood of normal subjects (N = 10) failed to adhere to glass in the presence of soluble adult worm antigenic preparation (SWAP). The non-adherence index (NAI) values for schistosomiasis patients were in the range of 11.0 to 72.3 (mean +/- SEM = 29.3 +/- 4.3), whereas the values for normal subjects were -56.0 to +2.0 (-25.9 +/- 7.6) and those for treated patients -59.6 to +4.0 (-19.3 +/- 5.8). Our results show that the colorimetric LAI assay can be used as an auxiliary test for the diagnosis of schistosomiasis.

Cell Adhesion↗
PubMed1991

A microcalorimetric assay to measure the reactivity of antigen-stimulated mononuclear cells from Schistosoma mansoni-infected patients.

The reactivity of mononuclear cells (2 x 10(6)/ml minimum Eagle's medium, MEM) from normal subjects and from Schistosoma mansoni-infected patients was evaluated by microcalorimetry. The results which are reported as heat production (mcal for 2 x 10(6) cells in 3600 s), were 2,087 +/- 21.3 and 2,497.0 +/- 21.3 for mononuclear cells from infected patients (N = 8) under stimulation with S. mansoni soluble egg antigen (SEA) and soluble adult worm antigenic preparation (SWAP), respectively. The values for cells from normal subjects (N = 8) were 13.7 +/- 1.1 and 29.3 +/- 3.2 in the presence of the same antigens. Pre-treatment of mononuclear cells from patients with 1 mM aminophylline (a cAMP phosphodiesterase inhibitor) totally abolished heat production. Cell viability (greater than 95%) was not changed after the measurement. The microcalorimetric assay described here measures the cellular metabolic activity and we feel justified in suggesting this technique as an auxiliary diagnosis of schistosomiasis. Given the sensitivity, precision and accuracy of this microcalorimetric assay, we feel it can be used for the diagnosis of disease conditions for which a reliable diagnostic method is required.

Animals↗
PubMed1990

Correlation between the lack of mononuclear cell cytotoxicity against schistosomula in vitro and inositolphosphate turnover in patients with schistosomiasis.

A comparison was made of the reactivity of mononuclear cells from normal subjects and from S. mansoni-infected patients. The following parameters were evaluated: 1) ability of mononuclear cells to kill schistosoma in the presence of complement; 2) [3H]-inositol incorporation into phosphatidylinositol (PI) and the rate of inositolphosphates (IPx) released. Cells from normal subjects, but not from S. mansoni-infected patients, were able to kill schistosomula in vitro. A decrease in inositolpolyphosphates (IPx) was observed for phytohemagglutinin (PHA)-stimulated mononuclear cells from infected patients when compared with mononuclear cells from normal subjects after 24 h of incubation. The results suggest that the reactivity of mononuclear cells from infected patients is altered under conditions of nonspecific stimulation with PHA when compared with normal cells.

Animals↗
PubMed1988

Effect of granulocyte inhibitory factor on granuloma formation in mice infected with Schistosoma mansoni.

Mononuclear cells from patients infected with Schistosoma mansoni were able to produce a soluble material that inhibited the granulocyte cytotoxicity against schistosomula in a complement-dependent killing assay. This granulocyte inhibitory factor (GIF) appears to exist preformed in the mononuclear cells of patients, but it can also be released in the supernatant after antigenic stimulation (lymphokine-like). Only T lymphocytes were able to mediate the inhibition of granulocyte cytotoxicity against schistosomula in vitro. The treatment of S. mansoni-infected mice with GIF induced a significant decrease in the liver granuloma size.

Animals↗
PubMed1988

Modulation of sheep erythrocyte receptor expression by anti-CD4, anti-CD8, and anti-HLA antibodies.

The modulation of E receptors on T cells by anti-CD4 and/or anti-CD8 is reported. The percentage of E rosette-forming cells (RFC) was decreased when sheep erythrocyte and mononuclear cells were incubated in the presence of monoclonal antibodies anti-CD4 and/or anti-CD8. This inhibition was not due to shedding of the E receptor and it was reversed by 8-Br.-3',5' cyclic guanosine monophosphate (cGMP). In contrast, anti-HLA antibodies induced an enhancement of sheep erythrocyte receptor expression evaluated by RFC.

Antibodies↗
PubMed1987

Effect of corticosteroids and aminophylline on active E-rosette formation in patients with diabetic retinopathy.

The reactivity of lymphocyte that form active E-rosettes to corticosteroids and aminophylline were examined in diabetic retinopathy patients with normal intraocular pressure. Aminophylline induced a significant activation of active E-rosette formation when compared with normal subjects. Similar results were observed when diabetics' lymphocytes were tested with corticosteroids. These drugs appear to induce an increase of quantity of T11-sheep erythrocyte receptors on T cells, suggesting abnormalities in diabetics' lymphocytes reactivity.

Adult↗