Eosinophilopoietic factors prime eosinophils for increased interleukin-8 generation

[Study of cytokine signaling: the quest for immunomodulatory drugs interacting with cytokine production and activity]

I have been engaged in research and education in the fields of immunology and biochemistry at a medical college and college of pharmacy for 40 years. The original reasons why I began studying cytokines and some of the interests that have motivated me to continue working in the field of cytokine research are described: 1) the roles of cytokines in various immunological and inflammatory diseases (e.g., chemokines in bacterial infections and inflammatory diseases, particularly the role of interleukin-5 and eotaxins in eosinophilia); 2) the role of focal adhesion kinase in antiapoptosis and metastasis of melanoma; 3) recent findings on the role of JAK2/STAT pathways, particularly how JAK2V617F mutation induces dysregulated proliferation and tumorigenesis; and 4) the interactions of various chemical compounds and natural products in cytokine gene activation and signaling. Previous discoveries and published findings by my research group are described, along with comments and discussion pertaining to recent developments in the field.

Interleukin-5 and interleukin-8 in relation to eosinophils and neutrophils in nasal fluids from school children with seasonal allergic rhinitis

The objectives of this study were to measure interleukins 5 and 8 (IL-5 and IL-8) in relation to eosinophils and neutrophils, in nasal lavage fluids from 60 school children with allergic rhinitis, and to determine the influence of treatment with a topical steroid (budesonide) on the levels of the two cytokines. Highly sensitive enzyme immunoassays were used to analyze IL-5 and IL-8. IL-5 levels and relative eosinophil counts in nasal lavage fluid increased significantly in patients with allergic rhinitis during the pollen season, compared with values obtained before the start of the season, and decreased significantly after treatment with budesonide. By contrast, no significant changes in IL-8 or neutrophils were found during the pollen season, nor did they decrease following treatment. In the untreated patients, IL-5 levels correlated significantly with eosinophil counts but not with neutrophil counts, whereas IL-8 levels correlated with neutrophil counts but not with eosinophil counts. After budesonide treatment, the correlation between IL-8 and neutrophils remained, and a correlation between IL-8 and eosinophils emerged. These findings support the concepts that IL-5 has a key role in regulating eosinophils and that IL-8 is important for the regulation of neutrophils. Whereas IL-5 and relative eosinophil counts are profoundly affected by topical steroid treatment, IL-8 and neutrophils are not demonstrably affected by such treatment. It is possible that neutrophils, through the release of IL-8, could be chemotactic for eosinophils in steroid-treated patients.

Upregulation of TNF-alpha and IL-3 expression in lesional and uninvolved skin in different types of urticaria

BACKGROUND

Although mast cells are known to secrete a broad spectrum of proinflammatory and immunomodulatory cytokines, the role of these molecules in mast cell-dependent cutaneous inflammation is not clear.

OBJECTIVE

We decided to study biopsy specimens from lesional and nonlesional skin of patients with acute, chronic recurrent, delayed pressure, and cold urticaria; from fleeting wheals of prick test reactions to allergens; and from normal skin of nonallergic subjects.

METHODS

Cryostat sections were stained by immunohistochemistry with antibodies against IL-3, IL-8, TNF-alpha, and mast cell-specific tryptase. In serial sections with tryptase and each cytokine, reactivity of mast cells was studied as well.

RESULTS

Compared with normal skin and prick test reactions, immunoreactivity for TNF-alpha and IL-3 was significantly increased on endothelial and perivascular cells of the upper dermis in all urticaria lesions. In nonlesional skin comparable upregulation was noted on endothelial cells and for TNF-alpha on perivascular cells of patients with delayed pressure urticaria. In addition, TNF-alpha was expressed throughout the epidermis in lesional and nonlesional skin of patients with all types of urticaria, but not in normal control subjects. Sequential biopsy specimens from patients with cold urticaria showed upregulation of TNF-alpha and IL-3 on endothelial cells 30 minutes after elicitation of lesions with an ice cube. In contrast to these findings, epidermal immunoreactivity, as well as endothelial and perivascular cell expression of IL-8, were only slightly altered in urticaria compared with normal skin. In sequentially stained sections, few tryptase-positive mast cells reacted to TNF-alpha, few reacted to IL-3 in pressure urticaria only, and practically none stained for IL-8.

CONCLUSION

These findings suggest that the cytokines studied here are involved in the pathology of urticaria, possibly by inducing subthreshold inflammation in endothelial cells of uninvolved skin.

Glucocorticoids inhibit chemokine generation by human eosinophils

Recent identification of eosinophils as a cellular source of various cytokines suggests that eosinophil-derived cytokines contribute to allergic inflammation through either an autocrine or a paracrine fashion. The profound inhibitory effects of glucocorticoids (GCCs) on the production of various cytokines have been well recognized, however, there has been no definitive evidence that GCCs in fact inhibit cytokine generation by eosinophils. To verify the inhibitory ability of GCCs on eosinophil cytokine generation, we studied the effect of GCCs by determination of IL-8 and monocyte chemoattractant protein-1 (MCP-1) as parameters. Dexamethasone (DEX) inhibited both generation and secretion of IL-8 in a dose-dependent fashion. DEX also dampened formyl-methionyl-leucyl-phenylalanine-or ionomycin-induced eosinophil IL-8 production. Furthermore, MCP-1 production was also inhibited by DEX. The slope and the shape of the dose-response curve of DEX were similar irrespective of either the input stimuli or the output cytokines; half-maximal inhibition was observed at 10(-8) mol/L, and nearly complete abolishment was observed at 10(-7) mol/L. The competitive polymerase chain reaction for IL-8 mRNA and semiquantitative polymerase chain reaction for MCP-1 mRNA revealed that the inhibition occurred at a level of pretranslation. These results indicate that the beneficial effect of GCCs in allergic inflammation might be related, at least in part, to a direct effect of the drugs on eosinophil cytokine synthesis.