Das D K, Saini M, Dhara A, Swarup D, Kumar S, Gupta P K
Centre for Wildlife, Indian Veterinary Research Institute, Izzatnagar, Uttar Pradesh, India.
Int J Immunogenet. 2008 Jun;35(3):227-34. doi: 10.1111/j.1744-313X.2008.00760.x. Epub 2008 Feb 28.
Toll-like receptors play role in the innate immune responses and orchestrate the adaptive immunity by induction of proinflammatory cytokines and up-regulation of costimulatory molecules. The present study has characterized TLR2 cDNA in nilgai, buffalo, sheep and goat that recognizes the peptidoglycan of Gram-positive bacteria. TLR2 coding sequences were amplified from monocytes cDNA and cloned in pGEMT-easy vector for nucleotide sequencing. Sequence analysis revealed 2355-bp-long TLR2 open reading frame encoding 784 amino acids in all the species studied. Nilgai TLR2 has 97.8% to 95.1% identity at nucleotide level and 96.2% to 92.7% identity at amino acid level with other ruminant species studied. Nonsynonymous substitutions exceeding synonymous substitutions indicated evolution of this receptor through positive selection among ruminants. Furthermore, basal TLR2 messenger RNA expression in different immune cells and tissues quantified by real-time polymerase chain reaction revealed highest level in in vitro derived dendritic cells followed by peripheral blood mononuclear cells. Skin and testes also expressed significant level in both nilgai and buffalo. Comparatively, nilgai immune cells and tissues expressed more TLR2 transcript than buffalo, thus elucidating stronger armamentarium of antibacterial immunity in nilgai as compared to buffalo.
Toll样受体在先天性免疫反应中发挥作用，并通过诱导促炎细胞因子和上调共刺激分子来协调适应性免疫。本研究对蓝牛、水牛、绵羊和山羊中识别革兰氏阳性菌肽聚糖的TLR2 cDNA进行了特征分析。从单核细胞cDNA中扩增TLR2编码序列，并克隆到pGEMT-easy载体中进行核苷酸测序。序列分析显示，在所研究的所有物种中，TLR2开放阅读框长2355 bp，编码784个氨基酸。蓝牛TLR2与其他反刍动物物种在核苷酸水平上的同一性为97.8%至95.1%，在氨基酸水平上的同一性为96.2%至92.7%。非同义替换超过同义替换表明该受体在反刍动物中通过正选择进化。此外，通过实时聚合酶链反应定量不同免疫细胞和组织中的基础TLR2信使RNA表达，结果显示体外衍生的树突状细胞中表达水平最高，其次是外周血单核细胞。皮肤和睾丸在蓝牛和水牛中也有显著表达。相比之下，蓝牛的免疫细胞和组织比水牛表达更多的TLR2转录本，从而说明与水牛相比，蓝牛具有更强的抗菌免疫能力。
