The IL-17 cytokine family and their role in allergic inflammation

Systemic administration of sphingosine-1-phosphate increases bronchial hyperresponsiveness in the mouse

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that plays important roles in allergic responses, including asthma. S1P acts on many cell types, such as mast cells, the airway epithelium, airway smooth muscle, and many immune cells. In this study we have evaluated whether a systemic administration of S1P to Balb/c mice modifies airway reactivity. Our data show that S1P (0.1-10 ng) given subcutaneously to Balb/c mice causes a specific and dose-dependent increase in cholinergic reactivity of bronchial tissues in vitro. This effect is (1) dose dependent, with a maximal effect of the dose of 10 ng of S1P; and (2) time dependent, reaching a maximal effect 21 days after S1P administration. Similarly, in the whole lung assay there is a dose- and time-dependent increase in lung resistance. Lungs isolated from S1P-treated mice displayed an increase in mast cell number. Furthermore, there is an increase of IL-4, IL-13, and IL-17 production. In conclusion, our data demonstrate that S1P signaling is involved in the complex pathway underlying airway hyperresponsiveness.

Monoclonal antibodies and other biologic agents in the treatment of asthma

Asthma represents a syndrome of airway inflammatory diseases with complex pathology. The immunologic pathogenesis is being increasingly revealed and provides opportunity for targeted biological intervention. Current experience with immunomodulators as targeted therapy in asthma is described in this literature review. Targeted therapies have included strategies to activate dendritic cells through the TLR-9 receptors, to interrupt the action of T(H)2 cytokines with cytokine blockers and monoclonal antibodies, to promote development of T(H)1 responses, to block IgE mediated pathways and to block TNFalpha. Omalizumab is the only biological therapy that has an approved indication in asthma at this time. An improved understanding of the heterogeneity of asthma should allow for specific targeting of different disease phenotypes specific therapies including immunomodulators.

Between a cough and a wheeze: dendritic cells at the nexus of tobacco smoke-induced allergic airway sensitization

Exposure to cigarette smoke represents a major risk factor for the development of asthma. Enhanced sensitization toward allergens has been observed in humans and laboratory animals exposed to cigarette smoke. Pulmonary dendritic cells (DCs) are crucially involved in sensitization toward allergens and play an important role in the development of T helper (Th)2-mediated allergic airway inflammation. We propose the concept that aberrant DC activation forms the basis for the deviation of the lung's default tolerogenic response toward allergic inflammation when harmless antigens are concomittantly inhaled with tobacco smoke. This review will summarize evidence suggesting that tobacco smoke can achieve this effect by providing numerous triggers of innate immunity, which can profoundly modulate airway DC biology. Tobacco smoke can affect the airway DC network either directly or indirectly by causing the release of DC-targeted mediators from the pulmonary tissue environment, resulting in the induction of a Th2-oriented pathological immune response. A thorough knowledge of the molecular pathways involved may open the door to novel approaches in the treatment of asthma.