Specific versus cooperative regulatory mechanisms of the cytokine genes that are clustered on the same chromosome

Species specialization in cytokine biology: is interleukin-4 central to the T(H)1-T(H)2 paradigm in swine?

The TH1-TH2 paradigm provides an elegant model of directed response to infectious pathogens. Developed in the mouse, the model has provided a framework for systematic and mechanistic studies of immune regulation, protective immunity, and vaccine development in swine. Interleukin-4 (IL-4) plays a central role in the paradigm as a regulatory molecule directing development of the TH2 phenotype, as a developmental cytokine essential for antibody production, and as a soluble diagnostic marker of the TH2 cell type. In contrast, while characterizing the biological properties of porcine IL-4, we discovered that it was not a stimulatory factor for porcine B cells. Rather, it blocked antibody and IL-6 secretion and suppressed antigen-stimulated proliferation of B cells. Inhibition was not reversed by treatment with IL-2 and IL-6 treatment. IL-4 did not stimulate T lymphocyte proliferation, but induced cell growth in lymphoblasts in a dose-dependent fashion. These results suggest that IL-4 plays a different role in pigs than in mice and humans, in which it stimulates B cells and is essential for antibody production. Furthermore, the functions of IL-4 in swine cannot be inferred from results in model systems such as the mouse. General models of disease resistance show substantial variation between pigs and mice at the cellular and molecular level. Advances in somatic cell technologies and animal engineering to enable gene knockouts in pigs, in combination with a continuously expanding immunological toolkit, promise an exciting future for pig immunology, detailed mechanistic elucidation of the TH1-TH2 paradigm, and an improved understanding of the role of IL-4 in porcine immunity to infectious disease.

Evidence of T-helper cell 2 cytokine regulation of chronic otitis media with effusion

Cytokine and cellular patterns of effusions may reflect stages of middle ear inflammation. The local interplay between IL-2 and -4 is likely to play a crucial role in the switching of inflammation in the chronic stage. The T-helper cell 2 (Th2) cytokines IL-4, -5 and -13 and the Th2/Th1 cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) regulate the cellular and molecular processes of chronic inflammation in the middle ear and therefore the chronic condition of otitis media with effusion (OME). Early identification of the cytokine and cellular patterns of effusions can be helpful in directing the clinical treatment of OME.We hypothesized that IL-2 and the group of Th2 cytokines regulate chronic inflammation in the middle ear and chronic OME. Effusions from children with persistent OME were analysed to determine the presence of cytokines (the Th1 cytokine IL-2, the Th2 cytokines IL-4, -5 and -13 and the Th1/Th2 cytokine GM-CSF), inflammatory cells (CD4+ T cells, eosinophils, macrophages and neutrophils) and mucin. Cytokines were evaluated by means of a quantitative "sandwich"-type ELISA, inflammatory cells by means of alkaline phosphatase-anti-alkaline phosphatase immunocytostaining and mucin by means of a modified periodic acid-Schiff method based on a slot-blot technique. The cytokine pattern in effusions varied from patient to patient. GM-CSF correlated positively and IL-4 inversely with IL-2 and the increased level of IL-4 may have had an inhibitory effect on IL-2. IL-5 and -13 correlated with IL-4. Inflammatory cells correlated with cytokines as follows: CD4+ T cells with IL-2 and -4; macrophages and neutrophils with GM-CSF; and eosinophils with IL-5. Some cytokine-cellular correlations in effusions were reflected at the clinical level. The mucin content of effusions correlated with the concentrations of IL-4 (>10 pg/ml) and -13, suggesting involvement of IL-4 and -13 in upregulation of the middle ear mucin metabolism.

Interleukin-3 and stress

The importance of cytokines as mediators in numerous physiologic and pathologic processes became apparent in the early seventies. In a relatively short period of time the number of characterized and functionally defined interleukins increased rapidly. Concomitantly, the understanding of their role in various important reactions in different systems of the organism in general, and in the interaction between the immune, central nervous and neuroendocrine systems in particular increased. IL-3 is one of the cytokines of great significance for hematopoiesis. In addition, it was shown that interleukin-3 (IL-3) participates in the response of the organism to various types of stress. Surprisingly enough, the reports on its production and activation during or following stress are rather scarce. Therefore, the purpose of this review is to try and compile the information on IL-3 and its role in different types of stress, and also to contribute our own modest experience on the subject.

Chromatin-based regulatory mechanisms governing cytokine gene transcription

On initial contact with antigen, naive T cells differentiate and acquire effector characteristics, including the ability to transcribe specific cytokine genes rapidly and at high levels on subsequent exposure to antigen. Several effector T-cell subsets showing distinct patterns of cytokine gene transcription have been described. The patterns of cytokine expression in response to pathogenic challenges have a significant impact on the outcome of immune and inflammatory reactions. Here we review recent studies suggesting that the ability of naive T cells to differentiate into specific cytokine-expressing cells is regulated by epigenetic changes in the accessibility and chromatin structure of cytokine genetic loci. Antigen and cytokine stimulation of naive T cells activates diverse intracellular signaling pathways, which result in chromatin remodeling and demethylation of cytokine genes. These changes are likely to increase, in a stable and heritable fashion, the accessibility of these genes to the basal transcriptional machinery. Chromatin-based regulatory mechanisms may explain several features of cytokine gene expression in effector versus naive T cells, including their monoallelic expression, coordinate regulation, and stable maintenance in memory T cells. The hypothesis of epigenetic changes occurring during T-cell differentiation provides a framework for a comprehensive understanding of cytokine expression by T cells.

Long-range transcriptional regulation of cytokine gene expression

Most studies on the control of cytokine gene expression have involved the functional analysis of proximal promoters. Recent work has identified distal elements that mediate long-range cytokine gene regulation and has implicated chromatin reorganization in regulation of cytokine gene loci. These studies have begun to elucidate the basis for cell-specificity and high-level expression of cytokine genes.

Genomic organization, sequence, and transcriptional regulation of the human eotaxin gene

Eotaxin is an eosinophil specific beta-chemokine assumed to be involved in eosinophilic inflammatory diseases such as atopic dermatitis, allergic rhinitis, asthma and parasitic infections. Its expression is stimulus- and cell-specific. We here describe the genomic organisation (3 exons of 132, 112 and 542 bp and 2 introns of 1211 and 378 bp) and sequence including 3 kb of DNA from the immediate 5' upstream region of the human eotaxin gene. Among the regulatory promoter elements potentially regulating eotaxin gene expression and/or mediating the effects of anti-inflammatory drugs we identified consensus sequences known to interact with nuclear factors like NF-IL6, AP-1, a NF-kappa-B like consensus sequence and gamma-interferon- as well as glucocorticoid response elements.