ABSTRACT
Semaphorin-3E (Sema-3E) is a member of a large family of proteins originally identified as axon guidance cues in neural development. It is expressed in different cell types, such as immune cells, cancer cells, neural cells, and epithelial cells. Subsequently, dys-regulation of Sema-3E expression has been reported in various biological processes that range from cancers to autoimmune and allergic diseases. Recent work in our laboratories revealed a critical immunoregulatory role of Sema-3E in experimental allergic asthma. We further speculate possible immune modulatory function(s) of Sema-3E on natural killer (NK) cells.
Subject(s)
Killer Cells, Natural/metabolism , Semaphorin-3A/metabolism , Animals , Humans , Semaphorin-3A/chemistry , Semaphorin-3A/genetics , Signal TransductionABSTRACT
BACKGROUND: IL-9 has been shown to affect the differentiation pathway of different cell types. However, its potential role in the maturation pathway of antigen-driven B-cell differentiation and its functional effects remain unknown. OBJECTIVE: To characterize IL-9 receptor alpha chain (IL-9R alpha) expression on human tonsillar B cells at different maturational stages, and to assess its effect on IgE production. METHODS: Freshly purified human tonsillar B cells were fractionated into 3 populations: low-density (LD), medium-density, and high-density cells. Expression levels of IL-9R alpha were determined by using immunohistochemistry and flow cytometry. IL-9R alpha(high)-expressing cells were stimulated with IL-9 in the presence or absence of IL-4, and IgE release was measured by ELISA. RESULTS: IL-9R alpha was expressed on human LD tonsillar B cells, with an ability to transduce signals through activation of signal transducer and activator of transcription 3 and 5. Although IL-9 was unable to induce IgE secretion by itself, it potentiated IL-4-mediated IgE production from LD cells. Moreover, increased IgE was paralleled by an upregulation of IL-9R alpha and CD27, with the latter a memory B-cell marker implicated in increased IgE secretion. CONCLUSION: These results highlight a crucial role for IL-9 in modulating T-cell-dependent B-cell differentiation and establish a new paradigm for understanding the synergistic role of T(H)2 cytokines and their modulatory effect on B-cell maturation and IgE production. CLINICAL IMPLICATIONS: IL-9 appears to be involved in memory B-cell differentiation and T(H)2-mediated allergic diseases such as asthma.
Subject(s)
B-Lymphocytes/immunology , Germinal Center/immunology , Immunoglobulin E/metabolism , Palatine Tonsil/immunology , Receptors, Interleukin-9/metabolism , B-Lymphocytes/chemistry , Cells, Cultured , Germinal Center/chemistry , Humans , Interleukin-4/pharmacology , Interleukin-9/pharmacology , Interleukin-9/physiology , Palatine Tonsil/chemistry , Phosphorylation , Receptors, Interleukin-9/analysis , Tumor Necrosis Factor Receptor Superfamily, Member 7/metabolism , Up-RegulationABSTRACT
BACKGROUND: The cytokine IL-4 is highly involved in T(H)2 inflammation, such as that seen in allergic rhinitis. IL-4 can induce IgE synthesis and eotaxin. Recent studies have shown that stimulation of allergic nasal tissue with ragweed allergen can induce local IL-4 mRNA production. OBJECTIVE: We set out to determine whether IL-4 antisense phosphorothioate-modified oligodeoxynucleotides (PS-ODNs) could inhibit IL-4 production and downstream events of IL-4. METHODS: Nasal mucosa biopsy specimens were obtained from patients with seasonal ragweed allergic rhinitis out of season, incubated ex vivo with or without PS-ODNs, and challenged with ragweed. FITC-labeled oligonucleotides were used to determine tissue uptake. By using immunocytochemistry, IL-4-, IL-13-, eotaxin 1-, and IFN-gamma-producing cells were enumerated, and by using in situ hybridization, epsilon germline transcript RNA- and IL-4 mRNA-positive cells were examined. RESULTS: The antisense PS-ODN was taken up by the tissue, and preincubation of the tissue with the IL-4 antisense PS-ODN caused a decrease in allergen-induced IL-4 mRNA and a decrease in the amount of IL-4 immunoreactivity (n = 7, P <.001). PS-ODNs had inhibitory effects on allergen-induced epsilon germline transcript RNA expression (n = 7, P <.001) and mucosa eotaxin 1 immunoreactivity (n = 7, P <.05). In contrast, the PS-ODNs increased the amount of IFN-gamma immunoreactivity (n = 7, P <.05), suggesting a nonspecific mechanism for reduced synthesis of IgE and eotaxin. CONCLUSIONS: Our results show that the IL-4 antisense PS-ODN effectively inhibits IL-4, IgE synthesis, and eotaxin, principal mediators of allergic inflammation, suggesting that PS-ODNs might offer a possible topical treatment for allergic rhinitis.
