Symposium 4: Vitamins, infectious and chronic disease during adulthood and aging Vitamin D and respiratory infection in adults
Symposium 4: Vitamins, infectious and chronic disease during adulthood and aging Vitamin D and respiratory infection in adults
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DOI：
10.1017/s0029665111003351
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发表时间：
2012-02-01
影响因子：
7
通讯作者：
Laaksi, Ilkka
中科院分区：
文献类型：
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作者：
Laaksi, Ilkka
维生素D不足是一个全球性问题，对健康具有重大影响。维生素D在骨矿化中的经典作用是众所周知的;维生素D缺乏会导致佝偻病、骨软化症或骨质疏松症。维生素D在免疫系统中的作用鲜为人知。维生素D不是一种真正的维生素，而是一种开环类固醇激素，在皮肤暴露于阳光UVB辐射后由7-脱氢胆固醇产生。营养和补充剂是北方国家冬季维生素D的主要来源，因为阳光照射不足以产生维生素D。为了激活维生素D，需要在肝脏中羟基化以形成25-羟基维生素D，并在肾脏中羟基化以形成1，25-二羟基维生素D，这是肠道中钙吸收中最活跃的激素。为了测定维生素D状态血清25-羟基维生素D水平，要测量激素的主要循环形式。维生素D通过与维生素D受体结合来调节基因表达，维生素D受体与维甲酸X受体二聚化。该复合物结合到维生素D响应基因的启动子区域内的维生素D响应元件。维生素D在先天免疫激活中具有关键作用;病原体脂肽刺激Toll样受体后产生的抗菌肽（抗菌肽和防御素）依赖于足够水平的25-羟基维生素D。临床上，有证据表明维生素D不足和呼吸道感染有关。还有一些证据表明，通过补充维生素D可以预防感染。有必要进行随机对照试验来探索这种预防作用。
Vitamin D insufficiency is a global issue that has significant implications for health. The classical role of vitamin D in bone mineralisation is well known; vitamin D deficiency leads to rickets, osteomalacia or osteoporosis. The role of vitamin D in an immune system is less known. Vitamin D is not an actual vitamin but a secosteroid hormone produced in the skin from 7-dehydrocholesterol after exposure to sunlight UVB radiation. Nutrition and supplements are main sources of vitamin D in wintertime in northern countries as sunlight exposure is inadequate for the production. For activation vitamin D needs to be hydroxylated in liver to form 25-hydroxyvitamin D and in kidney to 1,25-dihydroxyvitamin D, the most active hormone in Ca absorption in the gut. For determination of vitamin D status serum 25-hydroxyvitamin D level, the major circulating form of the hormone is to be measured. Vitamin D regulates gene expression through binding with vitamin D receptors, which dimerises with retinoid X receptor. This complex binds to vitamin D-responsive elements inside the promoter regions of vitamin D-responsive genes. Vitamin D has a key role in innate immunity activation; the production of antimicrobial peptides (cathelicidin and defensins) following Toll-like receptor stimulation by pathogen lipopeptides is dependent on sufficient level of 25-hydroxyvitamin D. Clinically, there is evidence of the association of vitamin D insufficiency and respiratory tract infections. There is also some evidence of the prevention of infections by vitamin D supplementation. Randomised controlled trials are warranted to explore this preventive effect.