Publisher Summary This chapter focuses on interleukin-8 (IL-8) and related chemotactic cytokines—namely, CXC and CC chemokines. IL-8 is the best known member of a new class of cytokines that are widely studied because of their ability to attract and activate leukocytes, and their potential role as mediators of inflammation. IL-8 was originally isolated from the culture supernatants of stimulated human blood monocytes and was identified as a protein of 72 amino acids with a molecular weight of 8383. The three-dimensional structure of IL-8 has been studied by nuclear magnetic resonance spectroscopy and X-ray crystallography. In concentrated solution, and on crystallization, IL-8 is present as a dimer. The first CC chemokine was identified after cloning by differential hybridization from human tonsillar lymphocytes and was termed LD78. The CC and CXC chemokines are similar in size and have an overall structure that is characterized by the two intrachain disulfide bonds, short N-terminal and long C-terminal sequences. It discusses the role of chemokines in pathology with skin inflammation because psoriasis was the first disease to be linked to overproduction of IL-8. Several independent studies document the occurrence of high levels of IL-8 in the synovial fluid of inflamed joints of patients with different forms of rheumatic diseases, osteoarthritis, and gout.

Interleukin-8 and related chemotactic cytokines--CXC and CC chemokines.

Agents that increase the permeability of the outer membrane.

Chemokines

CONTENTS INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 FIVE CHEMICALLY DIFFERENT GROUPS OF PEPTIDE ANTIBIOTICS . . . . . . . . . . .. 63 Linear, Mostly Helical, Peptides Without Cys, With or Without a Hinge . . . . . . . . . . . . . . . 63 Linear Pep tides Without Cys and with a High Proportion of Certain Residues . . . . . . . . . 67 Antibacterial Peptides with One Disulfide Bond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Peptides with Two or More S-S Bonds Giving Mainly or Only fJ-Sheet Structures. . . . . . . 69 Antibacterial Peptides Derivedfrom Larger Polypeptides with Other Known Functions . . 72 ANTIBACTERIAL PROTEINS AND ACTIVE FRAGMENTS OF SUCH PROTEINS . . . . 73

Peptide antibiotics and their role in innate immunity.

The use of various transgenic mouse models and analysis of human tumour biopsies has shown that bone marrow-derived myeloid cells, such as macrophages, neutrophils, eosinophils, mast cells and dendritic cells, have an important role in regulating the formation and maintenance of blood vessels in tumours. In this Review the evidence for each of these cell types driving tumour angiogenesis is outlined, along with the mechanisms regulating their recruitment and activation by the tumour microenvironment. We also discuss the therapeutic implications of recent findings that specific myeloid cell populations modulate the responses of tumours to agents such as chemotherapy and some anti-angiogenic therapies.

The role of myeloid cells in the promotion of tumour angiogenesis

Histamine Release and Assay Methods for the Study of Human Allergy

In order to minimize the adverse effect of histamine release in the rat of some gonadotropin releasing hormone (GnRH) antagonists, such as [Ac-D2Nal1,D4FPhe2,DTrp3,DArg6]-GnRH, new structures with modifications at positions 1, 2, 3, 5, 6, 7, and 10 were synthesized and tested in several biological systems. In vitro: the affinity for the pituitary GnRH receptor was measured as was the ability of the analogues to inhibit GnRH-stimulated release of luteinizing hormone (LH) by dispersed anterior pituitary cells in culture and to release histamine from rat mast cells. In vivo: inhibition of ovulation in the cycling rat was determined after subcutaneous (sc) injection of the peptides at noon on the day of proestrus; the duration of action of the peptides was evaluated by measuring LH levels in the castrated male rat after sc injection of some selected analogues. [Ac-D2Nal1,D4ClPhe2,D3Pal3,Arg5,D-4-p-methoxy benzoyl-2-aminobutyric acid6,DAla10]-GnRH was found to be one of the most potent analogues of this series, causing a 100% inhibition of ovulation at 5 micrograms/kg or less. Release of histamine was observed at doses 10-25 times that required for [Ac-D2Nal1,D4FPhe2,DTrp3,DArg6]-GnRH. Thus, introduction of arginine in position 5 with a hydrophobic amino acid in position 6 is compatible with high potency in several biological systems and results in compounds with lowered potency to release histamine compared to homologous peptides with tyrosine in position 5 and D-arginine in position 6.

New effective gonadotropin releasing hormone antagonists with minimal potency for histamine release in vitro

Small, acylated, methionine-containing peptides release histamine from human basophils. The characteristics of this reaction were compared to that of C5a- and IgE-induced release. fMet peptide-induced release requires Ca++ and is inhibited by EDTA in a manner similar to IgE- and C5a-mediated reactions. The fMet-Phe-Met-initiated reaction is complete within 2 min at temperatures of 25, 30, and 37 degrees C; but does not occur at 0 degrees C. There was a large variation in the capacity of leukocytes from different donors to release histamine with fMet peptides. However, there was no correlation in the capacity of leukocytes to release histamine with fMet-Phe-Met and their release with C5a or anti-IgE. The release by fMet-Phe-Met (but not by C5a or anti-IgE) was reversibly inhibited by a nonreleasing tripeptide. Leukocytes could be desensitized to the action of active fMet-peptide by preincubation with the peptide in the absence of cations. After washing, these cells released normally with C5a or anti-IgE. Conversely, cells desensitized to the action of C5a- or IgE-mediated reactions released normally with fMet peptides. There was cross-desensitization between different active peptides, and inactive peptides could not desensitize the leukocytes. Pharmacologic agents had similar effects on C5a and fMet peptide-induced release (e.g., lack of enhancement with deuterium oxide; enhancement with cytochalasin B; and inhibition with aminophylline and dibutyryl cyclic AMP). Therefore, histamine release with fMet peptides is initiated by their binding to and activation of a specific receptor on the basophil; the reaction beyond that point is similar to the C5a-mediated reaction.

Mechanism of Histamine Release by Formyl Methionine-Containing Peptides

Neutrophil attractant/activation protein-1 (NAP-1) causes human basophil histamine release.

The activation of human serum complement by incubation with zymosan generates C5a which releases histamine from autologous basophils. The characteristics of the C5a-induced histamine release were investigated. It is similar to IgE-mediated reactions in requiring Ca++ and in being inhibited by EDTA. However, it has marked differences from IgE-mediated reactions. C5a, at all concentrations, released histamine completely in less than 2 min. The C5a reaction has a narrow pH optimum that antigen-induced release and occurs well at 17 degrees to 37 degreesC but not at 0 degreesC. The optimal reaction temperature is 25 degrees to 30 degrees C. Unlike the antigen-induced release, no two-stage activation with C5a for the release of histamine could be demonstrated. There was additive release between C5a- IgE-mediated reactions. Leukocytes could be desensitized to the C5a-mediated reaction by 1) incubating the cells at 37 degrees C for 45 min, 2) pretreating the leukocytes with activated serum in the presence of EDTA, and 3) adding the activated serum to the leukocytes at 0 degrees C before transferring to the optimal reaction temperatures. Cells desensitized to the complement-induced release have normal reactions to IgE-mediated histamine release. In parallel experiments, cells from allergic donors desensitized for IgE-mediated reactions by incubation with antigen under sub-optimal conditions release histamine normally upon the addition of C5a. The results indicate that histamine release by C5a involves a mechanism of basophil activation that is different from the pathway involved in the IgE-induced reaction.

Complement-Induced Histamine Release from Human Basophils II. Mechanism of the Histamine Release Reaction

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