Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colonystimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release.Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 mM-100 mM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 mM). The cells were then stimulated with interleukin (IL)-1b and/or tumour necrosis factor (TNF)-a (10 ng?mL -1 ) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E 2 measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1b-induced GM-CSF release and markedly reduced TNF-a-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE 2 release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect.In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma.

Pulmonary silicosis is a deadly disease which kills thousands of people every year worldwide. The disease initially develops as an inflammatory response with recruitment of inflammatory cells into the lung controlled by multiple cytokines. The question whether these cytokines exert biological functions through signal transducing pathway remains unanswered along with the potential role of interleukin-6 receptor α (IL-6Rα) in regulating inflammatory cytokines. We aimed to assess the status of signal transducers and activator of transcription (Stat3), suppressor of cytokine signalling 3(Socs3) and inflammatory cytokines in airways of silica-exposed mice, and their relationship with IL-6Rα. Silica-exposed and silica-exposed IL-6Rα gene knockdown Balb/c mice were used in the study. Lung function was measured by plethysmography, mRNA expression of cytokines and signal molecules by qRT(2)-PCR and lung architecture by histopathology; T helper cell-type 2 (Th2) cytokines in broncho-alveolar lavage fluids were evaluated by ELISA and hydroxyproline in lung by colorimetry. Elevated levels of collagen deposition, signs of lung fibrosis, infiltration of inflammatory cells and presence of exfoliated mucosa in the lung of silica-exposed mice with concurrent increase in methacholine-induced specific resistance of airways were observed on day 60 post-exposure. In parallel, heightened expression of Th2 cytokines (IL-4, IL-5, IL-6) and signal molecules (Stat3 and Socs3) were observed in the airways of silica-exposed mice. Th1 (IL-1β and TNF-α) cytokines are underexpressed in majority of the airways tissues of silica-exposed mice. Silencing IL-6Rα in lung of silica-exposed mice down regulated the hypermorphic mRNA pool of potential Th2 cytokines and signal molecules. Hypermorphic expression of Th2 cytokines and signal molecules in airways of silica-exposed mice are mediated through IL-6Rα.

Tumor-necrosis factor-a (TNF-a)-driven nuclear factor-kB (NF-kB) activation and apoptosis are opposing pathways; the growing recognition of these conflicting roles of TNF-a is perplexing. Here, we show that inflammation and apoptosis are time-phased events following TNF-a signaling and that emergence of suppressor of cytokine signaling 3 (SOCS3) expression limits the ongoing NF-kB activation and promotes apoptosis; further, we suggest an altered view of how inflammatory diseases are initiated and sustained. In vitro, TNF-a (50 ng/ml) induced granulocyte SOCS3 protein, inhibited nuclear accumulation of the p65NF-kB subunit and enhanced apoptosis, as shown by DNA laddering, annexin V positivity, and overexpression of caspase-3 and Bax in the late phase, whereas the early phase was marked by NF-kB activation. Conversely, SOCS3 knockdown by small interfering RNA (siRNA) inhibited granulocyte apoptosis and enhanced nuclear accumulation of p65 and 59 lipooxygenase expression in the late phase of TNF-a signaling. As apoptosis is associated with SOCS3 abundance, we suggest that these divergent TNF-a-driven events are time-phased, interconnected, opposing control mechanisms and one of the central features through which the immune system resolves pulmonary inflammation. Dysregulation may initiate mucosal inflammation, thus changing the landscape of asthma therapy.

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Triazine-aryl-bis-indole derivative inhibits phosphodiesterase activity.