Whitmore Laura C, Hook Jessica S, Philiph Amanda R, Hilkin Brieanna M, Bing Xinyu, Ahn Chul, Wong Hector R, Ferguson Polly J, Moreland Jessica G
Department of Pediatrics, University of Iowa, Iowa City, IA 52242; Iowa Inflammation Program, University of Iowa, Iowa City, IA 52242;
Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390; Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390;
J Immunol. 2016 Feb 1;196(3):1376-86. doi: 10.4049/jimmunol.1500856. Epub 2016 Jan 4.
Polymorphonuclear leukocytes (PMN) achieve an intermediate or primed state of activation following stimulation with certain agonists. Primed PMN have enhanced responsiveness to subsequent stimuli, which can be beneficial in eliminating microbes but may cause host tissue damage in certain disease contexts, including sepsis. As PMN priming by TLR4 agonists is well described, we hypothesized that ligation of TLR2/1 or TLR2/6 would prime PMN. Surprisingly, PMN from only a subset of donors were primed in response to the TLR2/1 agonist, Pam3CSK4, although PMN from all donors were primed by the TLR2/6 agonist, FSL-1. Priming responses included generation of intracellular and extracellular reactive oxygen species, MAPK phosphorylation, integrin activation, secondary granule exocytosis, and cytokine secretion. Genotyping studies revealed that PMN responsiveness to Pam3CSK4 was enhanced by a common single-nucleotide polymorphism (SNP) in TLR1 (rs5743618). Notably, PMN from donors with the SNP had higher surface levels of TLR1 and were demonstrated to have enhanced association of TLR1 with the endoplasmic reticulum chaperone gp96. We analyzed TLR1 genotypes in a pediatric sepsis database and found that patients with sepsis or septic shock who had a positive blood culture and were homozygous for the SNP associated with neutrophil priming had prolonged pediatric intensive care unit length of stay. We conclude that this TLR1 SNP leads to excessive PMN priming in response to cell stimulation. Based on our finding that septic children with this SNP had longer pediatric intensive care unit stays, we speculate that this SNP results in hyperinflammation in diseases such as sepsis.
多形核白细胞（PMN）在受到某些激动剂刺激后会达到中间或预激活状态。预激活的PMN对后续刺激的反应性增强，这在消除微生物方面可能是有益的，但在某些疾病情况下，包括脓毒症，可能会导致宿主组织损伤。由于TLR4激动剂引发的PMN预激活已得到充分描述，我们推测TLR2/1或TLR2/6的连接会引发PMN预激活。令人惊讶的是，仅来自一部分供体的PMN在对TLR2/1激动剂Pam3CSK4的反应中被预激活，尽管来自所有供体的PMN都被TLR2/6激动剂FSL-1预激活。预激活反应包括细胞内和细胞外活性氧的产生、MAPK磷酸化、整合素激活、次级颗粒胞吐作用和细胞因子分泌。基因分型研究表明，TLR1中的一个常见单核苷酸多态性（SNP，rs5743618）增强了PMN对Pam3CSK4的反应性。值得注意的是，具有该SNP的供体的PMN表面TLR1水平较高，并且已证明TLR1与内质网伴侣gp96的结合增强。我们在一个儿科脓毒症数据库中分析了TLR1基因型，发现血液培养呈阳性且该与中性粒细胞预激活相关的SNP为纯合子的脓毒症或脓毒性休克患者在儿科重症监护病房的住院时间延长。我们得出结论，这种TLR1 SNP导致PMN在细胞刺激反应中过度预激活。基于我们的发现，具有该SNP的脓毒症儿童在儿科重症监护病房的住院时间更长，我们推测该SNP会导致脓毒症等疾病中的炎症反应过度。
