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Role of leptin in infection and autoimmunity
- G.N. Malavige (28 January 2003)
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G.N. Malavige, lecturer in Micobiology University of Sri Jayawardenapure, Sri Lanka.
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neelika{at}lassana.com G.N. Malavige
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Dear Editor Leptin is a cytokine involved in the regulation and generation of immune responses, particularly T cell responses. It is an adiposite-derived hormone structurally similar to IL-2,[1] which mainly acts as a T cell growth factor. Furthermore, it also regulates cytokine production, activates macrophages[3] and has an important role in angiogenesis and wound healing.[3] Concentrations of leptin increase during infection and inflammation. Leptin concentrations fall during starvation resulting in impaired cellular responses and thymic atrophy. Delayed hypersensitivity reactions are also impaired. This results in increased susceptibility to infection, which could be one of the main reasons of the high incidence of infectious diseases in malnourished children. However, studies have shown that low leptin concentrations may offer some resistance to autoimmune diseases[1] and that high leptin levels may even accelerate the autoimmune destruction of insulin producing beta cells in autoimmune diabetes.[2] The immune responses of many infections share many features of autoimmune infections. Both are characterised by high levels of IL-2, tumour necrosis factor alpha and enhanced reactivity of T helper 1 cells. However, the geographic distribution of these two conditions are quite different with infections and malnutrition being common in less developed countries while autoimmunity and obesity being common in affluent counties.[4] Therefore, modifying the leptin axis may be beneficial in infection and autoimmunity. References (1) Lord G. Role of leptin in immunology. Nutr Rev 2002 Oct;60(10 Pt 2):S35-8; discussion S68-84, 85-7 (2) Matarese G, Sanna V, Lechler RI, Sarvetnick N, Fontana S, Zappacosta S, La Cava A. Leptin accelerates autoimmune diabetes in female NOD mice. Diabetes 2002 May;51(5):1356-61. (3) Fantuzzi G, Faggioni R. Leptin in the regulation of immunity, inflammation, and hematopoiesis. J Leukoc Biol 2000 Oct;68(4):437-46 (4) Matarese G, La Cava A, Sanna V, Lord GM, Lechler RI, Fontana S, Zappacosta S. Balancing susceptibility to infection and autoimmunity: a role for leptin? Trends Immunol 2002 Apr;23(4):182-7 |
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