No abstract

Syk protein tyrosine kinase (PTK) is involved in signaling in leukocytes. In macrophages, Fcγ-receptor cross-linking induces Syk PTK phosphorylation and activation, resulting in Syk-dependent events required for phagocytosis and mediator release. We hypothesized that Syk antisense oligodeoxynucleotides (ASO) delivered by aerosol to rat lungs in vivo would depress Syk PTK expression, mediator release from alveolar macrophages, and Syk-dependent pulmonary inflammation. RT-PCR and RT-in situ PCR demonstrated that aerosolized Syk ASO administration reduced Syk mRNA expression from alveolar macrophages compared with cells isolated from sham-treated rats. Western blot analysis confirmed that Syk PTK expression was reduced after Syk ASO treatment. Compared with sham-treated rats (scrambled oligodeoxynucleotide), Syk ASO treatment suppressed Fcγ-receptor-mediated nitric oxide (86.0 ± 8.3%) and TNF (73.1 ± 3.1%) production by alveolar macrophages stimulated with IgG-anti-IgG complexes. In contrast, Fcγ-receptor-induced IL-1β release was unaffected by Syk ASO treatment. Additionally, Syk ASO suppressed Ag-induced pulmonary inflammation, suggesting that Syk ASO may prove useful as an anti-inflammatory therapy in disorders such as asthma.

No abstract

To investigate cytokine production stimulated by diesel exhaust particulates (DEP) and antigen through the intranasal route, mice were administered with DEP mixed with ovalbumin (OA) 3 times at an interval of 3 weeks. After the last instillation, cervical lymph node cells (LNC) were cultured in vitro with OA and antigen-presenting cells. The proliferative response to OA in cervical LNC from mice instilled with DEP and OA was noted to have increased significantly compared to mice instilled with OA alone. Interleukin 4 (IL-4) and interferon (IFN)-γ in culture supernatants were measured with ELISA. OA-stimulated IL-4 production in cervical LNC from mice instilled with DEP and OA markedly increased beyond that in the control mice. In contrast, OA-stimulated IFN-γ production in cervical LNC from mice instilled with OA was 3 times that for DEP and OA-instilled mice. OA-specific IgE antibody in sera showed a trend to be increased in mice intranasally instilled with DEP and OA. These results suggest that intranasal instillation of DEP and antigen in mice may modulate in vitro antigen-stimulated cytokine production from cervical LNC with a consequent increase in IgE antibody production.

To examine the potential effects of environmental pollutants on the production of cytokines in mast cells, mouse bone marrow-derived mast cells (BMMC) were cultured at various concentrations of diesel exhaust particulates (DEP) or for-maldeyhde. Proliferation of BMMC at 0.8, 2 and 4 μg/ml of DEP and 0.5 and 1 μg/ml of formaldehyde did not differ significantly from that of the controls (0 μg/ml) after 72 h culture, with the exception of a significant decrease in proliferation at 5 μg/ml of formaldehyde. Treatment with DEP or formaldehyde alone did not induce interleukin-4 (IL-4) or IL-6 production by BMMC. IL-4 and IL-6 production in BMMC stimulated with A23187 was higher in BMMC treated with low concentrations of DEP than in controls, but no increase was seen in BMMC treated with high DEP. IL-4 and IL-6 production in A23187-stimulated BMMC was significantly increased at 0.5 and 1 μg/ml formaldehyde but decreased at 5 μg/ml formaldehyde. After pretreatment with low DEP or formaldehyde alone for 24 h, IL-4 production of BMMC stimulated with A23187 was lower in BMMC treated with low DEP or formaldehyde than in controls. Antigen-induced IL-4 production significantly increased in BMMC treated with 0.4 or 0.8 μg/ml DEP or 0.5 μg/ml formaldehyde, but antigen-induced IL-6 production in BMMC did not increase at low DEP or formaldehyde. Although the enhancement of IL-4 production of BMMC stimulated with A23187 plus DEP was not completely inhibited by 5 × 10^––4M 2-mercaptoethanol (2-ME), treatment with 10^––7M dexamethasone inhibited further IL-4 production. Cytokine production of mast cells is thus shown here for the first time to be modulated by treatment with DEP or formaldehyde. Environmental pollutants such as DEP and formaldehyde may thus affect the immune response via the modulation of cytokine production in mast cells.