Critical role of IL-33, but not IL-25 or TSLP, in silica crystal-mediated exacerbation of allergic airway eosinophilia.

Silica crystals (silica), which are a major mineral component of volcanic ash and desert dust, contribute to the pathogenesis of pulmonary disorders such as asthma and fibrosis. Although administration of silica or sand dust to rodents exacerbates development of ovalbumin-induced or house dust mite-induced asthma-like airway inflammation, the detailed mechanisms remain unclear. Here, using murine models, we found that silica can induce IL-33 expression in pulmonary epithelial cells.

Platelets constitutively express IL-33 protein and modulate eosinophilic airway inflammation.

Background: Although platelets play a key role in allergic inflammation in addition to their well-established role in hemostasis, the precise mechanisms of how platelets modulate allergic inflammation are not fully understood. IL-33 is an essential regulator of innate immune responses and allergic inflammation.

Objective: We sought to determine the expression of IL-33 protein by platelets and its functional significance in airway inflammation.

IL-25 and IL-33 Contribute to Development of Eosinophilic Airway Inflammation in Epicutaneously Antigen-Sensitized Mice.

Background: IL-25, IL-33 and TSLP are produced predominantly by epithelial cells and are known to induce Th2-type cytokines. Th2-type cytokines are involved not only in host defense against nematodes, but also in the development of Th2-type allergic diseases. TSLP was reported to be crucial for development of allergic airway inflammation in mice after inhalation of allergens to which they had been sensitized epicutaneously (EC) beforehand.

An Interleukin-33-Mast Cell-Interleukin-2 Axis Suppresses Papain-Induced Allergic Inflammation by Promoting Regulatory T Cell Numbers.

House dust mite-derived proteases contribute to allergic disorders in part by disrupting epithelial barrier function. Interleukin-33 (IL-33), produced by lung cells after exposure to protease allergens, can induce innate-type airway eosinophilia by activating natural helper (NH) cells, a member of group 2 innate lymphoid cells (ILC2), to secrete Th2 type-cytokines. Because IL-33 also can induce mast cells (MCs) to secrete Th2 type-cytokines, MCs are thought to cooperate with NH cells in enhancing protease or IL-33-mediated innate-type airway eosinophilia.

Silica and double-stranded RNA synergistically induce bronchial epithelial apoptosis and airway inflammation.

Silica crystals (silica), which are the main mineral component of volcanic ash and desert dust, can activate the caspase-1-activating inflammasome in phagocytic cells to secrete IL-1β. Although inhalation of silica-containing dust is known to exacerbate chronic respiratory diseases, probably through inflammasome activation, its direct effects on bronchial epithelial cells remain unclear. Here, we show that silica and double-stranded RNA (dsRNA) synergistically induces caspase-9-dependent apoptosis, but not inflammasome activation, of bronchial epithelial cells.

Anti-inflammatory effects of high-dose IgG on TNF-α-activated human coronary artery endothelial cells.

High-dose infusion of IgG (IVIG) is used to treat autoimmune and inflammatory diseases, including Kawasaki disease (KD). Although the immunomodulatory effects of IVIG on blood cells such as macrophages have been well studied, its effects on tissue cells remain unclear. Here, we show that high-dose IgG specifically and completely inhibited TNF-α-induced, but not IL-1β-induced, secretion of proinflammatory cytokines such as G-CSF and IL-6 by cultured human coronary artery endothelial cells (HCAECs).