322,985 research outputs found
Study of synthetic peptides derived from PKI55, a PKC modulator, in stimulated human neutrophils.
No full textFor-Met-Leu-Phe-OH (fMLP) and its derivative methyl ester, fMLP-OMe, represent highly potent chemoattractants for neutrophils. The interaction of fMLP with its receptor (FPR) activates multiple second messengers and involves specific kinases such as protein kinase C (PKC) and mitogen activated protein kinases (MAPKs). We reported a strong relationship between specific PKC isoforms and human neutrophils function activated by formylpeptides [1]. Recently, we have identified the PKI55 protein that acts as a specific modulator of PKC [2]. We tested peptides derived from both C-terminal and N-terminal sequence of PKI55, with the objective to identify the portion of the protein maintaining the biochemical effect to inhibit PKC. Enzyme activity in vitro assay, using recombinant PKC isoforms, showed that the peptides G16, G8 and G5 (Tab.1), inhibited the specific PKC isozymes. These same peptides were used to evaluate in human neutrophils their ability to affect chemotaxis, superoxide and lysozyme release. Neutrophils were purified from peripheral blood of health donors, preincubated with peptides at concentration from 0,1μM, to 25μM and then activated with fMLP-OMe. Our data demonstrate that the peptides reduced chemotaxis, while superoxide generation and lysozyme release were never modified. Previously we demonstrated that chemotactic movement of neutrophils was mediated by activation of PKC β1 [3]. Since we suggest that the selected peptides act as PKC inhibitors, to confirm our hypothesis western blotting analysis were performed on neutrophils stimulated with fMLP-OMe in presence or absence of G16, G8 and G5 and PKC β1 levels were studied. The results confirmed the significant reduction of PKC β1 levels in presence of G16, G8 and G5 peptides in comparison with control samples. The peculiar inhibiting properties of the peptides render them a promising pharmacological tool to control the over-expression of PKC isoforms.
[1] Selvatici R., Falzarano S., Mollica A. and Spisani S. (2006) Eur J. Pharmacol 18:1-11
[2] Selvatici R., Melloni E., Ferrati m., Piubello C., Marincola F.C. And Gandini (2003) E. J. Mol Evol, 57:131-139. [3] Spisani S., Falzarano S., Traniello S., Nalli M. and Selvatici R. (2005) FEBS J. 272:883-91
Differences arising in human neutrophil activation passing from N-formyl to N-acetyl-oligopeptides
No full textN-formyl- and N-acetyl-peptides were synthesized and compared in order to understand which features can best elicit biological responses. The behavior of N-formyl-peptides confirms the previously found sequential obligations in the residues, while acetyl-derivatives do not seem suitable for an efficacious stimulation of human neutrophils
Does a relationship exist between neutrophil myeloperoxidase deficiency and the occurence of neoplasms ?
No full text36 unrelated individuals with neutrophil MPO deficiency, (10 totally MPO deficient) were found on screening a population of 148,000 subjects. A further 2 subjects with total and 22 with partial MPO deficiency were identified through family studies. The assessment of neutrophil function, i.e., peroxidase activity, superoxide anion generation, microbicidal activity towards fungi and bacteria, and locomotor behaviour, was carried out in 10 subjects with total and 4 with partial MPO deficiency. We found that the enzyme defect is associated with a marked impairment in the killing of both S. aureus and C. albicans, without affecting microbicidal activity against S. faecalis. There appears to be a high incidence of malignancy in patients with complete MPO deficiency, suggesting a relationship between a defective MPO system and neutrophil-mediated tumor cell cytotoxicity
Does a relationship exist between neutrophil myeloperoxidase deficiency and the occurrence of neoplasms?
No full text36 unrelated individuals with neutrophil MPO deficiency, (10 totally MPO deficient) were found on screening a population of 148,000 subjects. A further 2 subjects with total and 22 with partial MPO deficiency were identified through family studies. The assessment of neutrophil function, i.e., peroxidase activity, superoxide anion generation, microbicidal activity towards fungi and bacteria, and locomotor behaviour, was carried out in 10 subjects with total and 4 with partial MPO deficiency. We found that the enzyme defect is associated with a marked impairment in the killing of both S. aureus and C. albicans, without affecting microbicidal activity against S. faecalis. There appears to be a high incidence of malignancy in patients with complete MPO deficiency, suggesting a relationship between a defective MPO system and neutrophil-mediated tumor cell cytotoxicity
Synthesis and biological activity of D-glucopyranosyl peptide T derivatives
No full textThe solid phase procedure, based on the Fmoc (9-fluorenylmethyloxycarbonyl) chemistry, was used to prepare some peptide T analogues in which D-glucopyranosyl units are beta-O-glycosidically linked to Thr4 and/or Thr5 side chains. All glycopeptides showed significant human monocyte chemotaxis and high resistance to degradation by plasma or brain enzymes
Lymphocytes treated with natural alpha interferon produce a chemotactic factor for human neutrophils
No full textlymphocytes stimulated with alpha interferon released achemotactic factor for neutrophils. The process was not inhibited by cicloheximide, whereas mepacrine completely inhibited rellease of chemotacttic activity. Interferon did not stimulate lymphocytes to release a neutrophil chemotactic factor
A hydrophilic residue at position 2 can improve specific biological responses in fMLP‐OMe analogs
No full textThe peptides for-Met-Ser-Phe-OMe 1, for-Met-Cys-Phe-OMe 2, for-Met-Lys-Phe-OMe 3, and for-Met-Tyr-Phe-OMe 4 were synthesized in order to investigate the importance of a hydrophilic side-chain on the residue at position 2 on biological activities of human neutrophils. Our results seem to highlight that this type of substitution does not facilitate good chemotaxis, although it elicits both superoxide anion production and particularly lysozyme release, in some cases even more potent than the parent fMLP-OMe, if the hydrophilicity is associated with steric hindrance
Synthesis and biological activity of chelator-peptide T conjugates
No full textThe solid phase procedure was used to prepare two peptide T derivatives in which the 4-[(1,4,8,11-tetraazacyclotetradec-1-yl)methyl]benzoyl unit is linked to their N-terminus. In a human monocyte chemotaxis assay, both chelator-peptide conjugates showed a high binding property to the CD4 receptor, comparable to the parent H-D-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-NH2 and its pentapeptide fragment T(4-8)-NH2. These encouraging results make the above cyclam-oligopeptides candidates for the development of the CD4 receptor imaging agents
ACTIVATION OF NEUTROPHIL CYTOTOXICITY BY SYNERGISTIC ACTION OF TPA AND TARGET IMMUNIZATION
No full textABSTRACTS OF THE SEVENTH MEETING OF THE ITALIAN ASSOCIATION FOR CELL BIOLOGY AND DIFEFRENTIATION, 16-19 OCTOBER, SPOLETO, ITAL
Differential inhibition of signaling pathways by two new imidazo-pyrazoles molecules in fMLF-OMe- and IL8-stimulated human neutrophil
No full textN-formyl-methionyl-leucyl-phenylalanine (fMLF), its methyl ester fMLF-OMe and interleukin 8 (IL8) play a pivotal role in neutrophil chemotaxis regulation in the latter and early stages, respectively, but the mechanisms through which the signal transduction pathways activate this function are not yet completely understood. Compounds 3l and 3r, a new class of arylcarbamoyl-imidazo-pyrazoles derivatives, were described as the first example of compounds able to inhibit human neutrophil chemotaxis induced by both fMLF-OMe and IL8. Here, we report their effects on superoxide production and lysozyme release. No inhibition was observed, thus they could be defined as “pure” chemotactic antagonists. Therefore, such molecules were used to highlight specific kinases involved in neutrophil chemotaxis. Our data provide support that compounds 3l and 3r strongly inhibit p38 MAPK with either fMLF-OMe or IL8 chemoattractants, while they show different signaling pathways regarding PKC isoforms suggesting that a fine tuning of the neutrophil activation occurs through differences in the activation of signaling pathways. Neither fMLF-OMe nor IL8 were able to obtain activation of the PI3K/Akt pathway. Since anomalous activation of neutrophil recruitment is one of the causes of many inflammatory diseases, the good versatility of our derivatives could represent the most important characteristic of these new molecules in the development of novel therapeutics
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