Szalai A J, Briles D E, Volanakis J E
Department of Medicine, University of Alabama at Birmingham 35294, USA.
J Immunol. 1995 Sep 1;155(5):2557-63.
C-reactive protein (CRP) is an acute phase protein with a well known association with infection and other inflammatory conditions. Studies with use of purified CRP in in vitro assays provided early evidence that CRP has antibacterial activity. Subsequently it was shown that passively administered human CRP can protect mice from lethal infection with Streptococcus pneumoniae. In this study, we extend these observations to an in vivo model of host resistance by using human CRP transgenic mice. CRP transgenic mice experimentally infected with S. pneumoniae lived longer and had significantly lower mortality than their nontransgenic littermates. This increased resistance to infection was associated with q 10- to 400-fold reduction of bacteremia. Furthermore, male transgenics exhibited longer survival time than females, and this difference could be attributed to increased expression of CRP by males, which was mediated by testosterone. This study provides the first unequivocal evidence that CRP plays an important role in vivo in host defense against pneumococcal infections, and shows that sex hormones can affect expression of the human CRP transgene in mice.
C反应蛋白（CRP）是一种急性期蛋白，与感染及其他炎症状态有着众所周知的关联。在体外试验中使用纯化CRP进行的研究提供了早期证据，表明CRP具有抗菌活性。随后有研究表明，被动给予的人CRP可保护小鼠免受肺炎链球菌致死性感染。在本研究中，我们通过使用人CRP转基因小鼠，将这些观察结果扩展至宿主抵抗力的体内模型。实验感染肺炎链球菌的CRP转基因小鼠比其非转基因同窝小鼠存活时间更长，死亡率显著更低。这种对感染抵抗力的增强与菌血症降低10至400倍有关。此外，雄性转基因小鼠的存活时间比雌性更长，这种差异可归因于雄性小鼠CRP表达增加，这是由睾酮介导的。本研究提供了首个明确证据，表明CRP在体内对肺炎球菌感染的宿主防御中起重要作用，并表明性激素可影响小鼠中人CRP转基因的表达。
