ABSTRACT
Asthma is a chronic allergic disease characterized by airway inflammation, airway hyper-responsiveness (AHR), and mucus hypersecretion. T-lymphocytes are involved in the pathogenesis of asthma, mediating airway inflammatory reactions by secreting cytokines. The phosphoinositide 3-kinase (PI3K) and Notch signaling pathways are associated with T cell signaling, proliferation, and differentiation, and are important in the progression of asthma. Thus, compounds that can modulate T cell proliferation and function may be of clinical value. Here, we assessed the effects of tangeretin, a plant-derived flavonoid, in experimental asthma. BALB/c mice at postnatal day (P) 12 were challenged with ovalbumin (OVA). Separate groups of mice (n=18/group) were administered tangeretin at 25 or 50 mg/kg body weight by oral gavage. Dexamethasone was used as a positive control. Tangeretin treatment reduced inflammatory cell infiltration in bronchoalveolar lavage fluid (BALF) and also restored the normal histology of lung tissues. OVA-specific IgE levels in serum and BALF were reduced. AHR, as determined by airway resistance and lung compliance, was normalized. Flow cytometry analyses revealed a reduced Th17 cell population. Tangeretin reduced the levels of Th2 and Th17 cytokines and raised IFN-γ levels. PI3K signaling was inhibited. The expressions of the Notch 1 receptor and its ligands Jagged 1 and 2 were downregulated by tangeretin. Our findings support the possible use of tangeretin for treating allergic asthma.
Subject(s)
Animals , Mice , Asthma/drug therapy , Signal Transduction/drug effects , Anti-Asthmatic Agents/therapeutic use , Flavones/therapeutic use , Asthma/immunology , Cytokines/drug effects , Cytokines/immunology , Th2 Cells/drug effects , Th2 Cells/immunology , Th1 Cells/drug effects , Th1 Cells/immunology , Disease Models, Animal , Proto-Oncogene Proteins c-akt/drug effects , Proto-Oncogene Proteins c-akt/immunology , Th17 Cells/drug effects , Th17 Cells/immunology , Animals, Newborn , Mice, Inbred BALB CABSTRACT
BACKGROUND: CD4+ T cells play an important role in the initiation of an immune response by providing help to other cells. Among the helper T subsets, interferon-γ (IFN-γ)-secreting T helper 1 (Th1) and IL-17-secreting T helper 17 (Th17) cells are indispensable for clearance of intracellular as well as extracellular pathogens. However, Th1 and Th17 cells are also associated with pathogenesis and contribute to the progression of multiple inflammatory conditions and autoimmune diseases. RESULTS: In the current study, we found that BJ-1108, a 6-aminopyridin-3-ol analogue, significantly inhibited Th1 and Th17 differentiation in vitro in a concentration-dependent manner, with no effect on proliferation or apoptosis of activated T cells. Moreover, BJ-1108 inhibited differentiation of Th1 and Th17 cells in ovalbumin (OVA)-specific OT II mice. A complete Freund's adjuvant (CFA)/OVA-induced inflammatory model revealed that BJ-1108 can reduce generation of proinflammatory Th1 and Th17 cells. Furthermore, in vivo studies showed that BJ-1108 delayed onset of disease and suppressed experimental autoimmune encephalomyelitis (EAE) disease progression by inhibiting differentiation of Th1 and Th17 cells. CONCLUSIONS: BJ-1108 treatment ameliorates inflammation and EAE by inhibiting Th1 and Th17 cells differentiation. Our findings suggest that BJ-1108 is a promising novel therapeutic agent for the treatment of inflammation and autoimmune disease.
Subject(s)
Animals , Female , Mice , Cell Differentiation/drug effects , Th1 Cells/drug effects , Encephalomyelitis, Autoimmune, Experimental/drug therapy , Th17 Cells/drug effects , Aminopyridines/pharmacology , Aniline Compounds/pharmacology , Spleen/immunology , CD4-Positive T-Lymphocytes/drug effects , CD4-Positive T-Lymphocytes/immunology , Reproducibility of Results , Apoptosis/drug effects , Apoptosis/immunology , Th1 Cells/immunology , Cell Proliferation/drug effects , Disease Models, Animal , Encephalomyelitis, Autoimmune, Experimental/immunology , Th17 Cells/immunology , Flow Cytometry , Aminopyridines/immunology , Aniline Compounds/immunology , Lymph Nodes/immunology , Mice, Inbred C57BLABSTRACT
T-helper (Th)17 cell responses are important for the development of neutrophilic inflammatory disease. Recently, we found that acetyl salicylic acid (ASA) inhibited Th17 airway inflammation in an asthma mouse model induced by sensitization with lipopolysaccharide (LPS)-containing allergens. To investigate the mechanism(s) of the inhibitory effect of ASA on the development of Th17 airway inflammation, a neutrophilic asthma mouse model was generated by intranasal sensitization with LPS plus ovalbumin (OVA) and then challenged with OVA alone. Immunologic parameters and airway inflammation were evaluated 6 and 48 h after the last OVA challenge. ASA inhibited the production of interleukin (IL)-17 from lung T cells as well as in vitro Th17 polarization induced by IL-6. Additionally, ASA, but not salicylic acid, suppressed Th17 airway inflammation, which was associated with decreased expression of acetyl-STAT3 (downstream signaling of IL-6) in the lung. Moreover, the production of IL-6 from inflammatory cells, induced by IL-17, was abolished by treatment with ASA, whereas that induced by LPS was not. Altogether, ASA, likely via its acetyl moiety, inhibits Th17 airway inflammation by blockade of IL-6 and IL-17 positive feedback.