Yeh Chiou-Yueh, Shun Chia-Tung, Kuo Yu-Min, Jung Chiau-Jing, Hsieh Song-Chou, Chiu Yen-Ling, Chen Jeng-Wei, Hsu Ron-Bin, Yang Chia-Ju, Chia Jean-San
Graduate Institute of Immunology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China.
Department of Forensic Medicine, National Taiwan University Hospital, Taipei, Taiwan, Republic of China.
Infect Immun. 2015 Jun;83(6):2202-12. doi: 10.1128/IAI.02965-14. Epub 2015 Mar 16.
The mechanisms that underlie valvular inflammation in streptococcus-induced infective endocarditis (IE) remain unclear. We previously demonstrated that streptococcal glucosyltransferases (GTFs) can activate human heart valvular interstitial cells (VIC) to secrete interleukin-6 (IL-6), a cytokine involved in T helper 17 (Th17) cell differentiation. Here, we tested the hypothesis that activated VIC can enhance neutrophil infiltration through sustained IL-17 production, leading to valvular damage. To monitor cytokine and chemokine production, leukocyte recruitment, and the induction or expansion of CD4(+) CD45RA(-) CD25(-) CCR6(+) Th17 cells, primary human VIC were cultured in vitro and activated by GTFs. Serum cytokine levels were measured using an enzyme-linked immunosorbent assay (ELISA), and neutrophils and Th17 cells were detected by immunohistochemistry in infected valves from patients with IE. The expression of IL-21, IL-23, IL-17, and retinoic acid receptor-related orphan receptor C (Rorc) was upregulated in GTF-activated VIC, which may enhance the proliferation of memory Th17 cells in an IL-6-dependent manner. Many chemokines, including chemokine (C-X-C motif) ligand 1 (CXCL1), were upregulated in GTF-activated VIC, which might recruit neutrophils and CD4(+) T cells. Moreover, CXCL1 production in VIC was induced in a dose-dependent manner by IL-17 to enhance neutrophil chemotaxis. CXCL1-expressing VIC and infiltrating neutrophils could be detected in infected valves, and serum concentrations of IL-17, IL-21, and IL-23 were increased in patients with IE compared to healthy donors. Furthermore, elevated serum IL-21 levels have been significantly associated with severe valvular damage, including rupture of chordae tendineae, in IE patients. Our findings suggest that VIC are activated by bacterial modulins to recruit neutrophils and that such activities might be further enhanced by the production of Th17-associated cytokines. Together, these factors can amplify the release of neutrophilic contents in situ, which might lead to severe valvular damage.
链球菌诱导的感染性心内膜炎（IE）中瓣膜炎症的潜在机制尚不清楚。我们之前证明，链球菌葡糖基转移酶（GTFs）可激活人心脏瓣膜间质细胞（VIC）分泌白细胞介素-6（IL-6），这是一种参与辅助性T细胞17（Th17）细胞分化的细胞因子。在此，我们检验了这样一个假说：活化的VIC可通过持续产生IL-17增强中性粒细胞浸润，从而导致瓣膜损伤。为监测细胞因子和趋化因子的产生、白细胞募集以及CD4(+) CD45RA(-) CD25(-) CCR6(+) Th17细胞的诱导或扩增，将原代人VIC进行体外培养并用GTFs激活。使用酶联免疫吸附测定（ELISA）测量血清细胞因子水平，通过免疫组织化学检测IE患者感染瓣膜中的中性粒细胞和Th17细胞。IL-21、IL-23、IL-17和视黄酸受体相关孤儿受体C（Rorc）的表达在GTF激活的VIC中上调，这可能以IL-6依赖的方式增强记忆性Th17细胞的增殖。许多趋化因子，包括趋化因子（C-X-C基序）配体1（CXCL1），在GTF激活的VIC中上调，这可能募集中性粒细胞和CD4(+) T细胞。此外，IL-17以剂量依赖的方式诱导VIC中CXCL1的产生，以增强中性粒细胞趋化性。在感染瓣膜中可检测到表达CXCL1的VIC和浸润的中性粒细胞，与健康供体相比，IE患者血清中IL-17、IL-21和IL-23的浓度升高。此外，IE患者血清IL-21水平升高与严重瓣膜损伤（包括腱索断裂）显著相关。我们的研究结果表明，VIC被细菌调节素激活以募集中性粒细胞，并且Th17相关细胞因子的产生可能会进一步增强这种活性。这些因素共同作用可原位放大嗜中性粒细胞内容物的释放，这可能导致严重的瓣膜损伤。
