Regulatory T cells in asthma.
Asthma is characterized by T helper cell 2 (Th2) type inflammation, leading to airway hyperresponsiveness and tissue remodeling. Th2 cell-driven inflammation is likely to represent an abnormal response to harmless airborne particles. These reactions are normally suppressed by regulatory T cells, which maintain airway tolerance. The anti-inflammatory cytokine IL-10 is likely to play a central role. The role of the cytokine transforming growth factor beta (TGF-beta) is more complex, with evidence for immune suppression and remodeling in the airways. In asthmatic individuals there is a breakdown in these regulatory mechanisms. There is emerging evidence that early life events, including exposure to allergen and infections, are critical in programming effective regulatory pathways to maintain pulmonary homeostasis. In this review we examine the clinical and experimental evidence for T regulatory cell function in the lung and discuss the events that might influence the functioning of these cells. Ultimately, the ability to enhance regulatory function in affected individuals may represent an effective treatment for asthma.
Lloyd
Clare M
CM
Medical Research Council and Asthma UK Centre in Allergic Mechanisms of Asthma, NHLI, Imperial College, London SW7 2AZ, UK. c.lloyd@imperial.ac.uk
Hawrylowicz
Catherine M
CM
D000818:Animals; D001249:Asthma / Q000235:genetics / Q000276:immunology*; D006706:Homeostasis; D006801:Humans; D018928:Immunity, Mucosal; D016753:Interleukin-10 / Q000096:biosynthesis / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000276:immunology
D016212:Transforming Growth Factor beta; D016753:Interleukin-10