García-Gómez Elizabeth, Miranda-Ozuna Jesús F T, Díaz-Cedillo Francisco, Vázquez-Sánchez Ernesto A, Rodríguez-Martínez Sandra, Jan-Roblero Janet, Cancino-Diaz Mario E, Cancino-Diaz Juan Carlos
Departments of Microbiology, Escuela Nacional de Ciencias Biológicas-Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N Col, Santo Tomas, Deleg, Miguel Hidalgo, Mexico City, Mexico.
Unidad de Investigación en Reproducción Humana, CONACyT-Instituto Nacional de Perinatología, Montes Urales 800, Col, Lomas Virreyes Deleg, Miguel Hidalgo, Mexico City, Mexico.
J Med Microbiol. 2017 Jul;66(7):864-873. doi: 10.1099/jmm.0.000502. Epub 2017 Jun 22.
Staphylococcus epidermidis ATCC12228 lipoteichoic acid (LTA) inhibits TNFα production from keratinocytes that are activated with poly I:C. However, this effect has not been proven in clinical or commensal isolates.
The <10 kDa fractions of S. epidermidis isolates from ocular infections (n=56), healthy skin (n=35) and healthy conjunctiva (n=32) were obtained. TNFα production was determined by elisa in HaCaT keratinocytes stimulated with poly I:C and with the <10 kDa fractions. LTA in the cytoplasmic membrane and in the <10 kDa fractions of the isolates was determined during bacterial growth by flow cytometry, Western blot and electrospray ionization mass spectrometry. The expression levels of ugtP, ltaA and ltaS were evaluated.
Two populations of isolates were found: a population that inhibited TNFα production (TNFα-inhibitor isolates) and a population that did not inhibit it (TNFα non-inhibitor isolates). The cells from the TNFα-inhibitor isolates had less LTA in the cytoplasmic membrane compared to the cells from the TNFα non-inhibitor isolates (P<0.05). Similarly, LTA was detected in the supernatants of TNFα-inhibitor isolates, and it was absent in TNFα non-inhibitor isolates. High expression levels of the ugtP and ltaA genes in the 1850I (TNFα-inhibitor isolate) and 37HS (TNFα non-inhibitor isolate) isolates were found during bacterial growth. However, the ltaS gene had a low expression level (P<0.05) in the 37HS isolate.
The TNFα-inhibitor isolates release LTA due to high expression of the LTA synthesis genes. By contrast, TNFα non-inhibitor isolates do not release LTA due to low expression level of the ltaS gene.
表皮葡萄球菌ATCC12228脂磷壁酸（LTA）可抑制经聚肌胞苷酸（poly I:C）激活的角质形成细胞产生肿瘤坏死因子α（TNFα）。然而，这一效应在临床分离株或共生分离株中尚未得到证实。
获取眼部感染（n = 56）、健康皮肤（n = 35）和健康结膜（n = 32）的表皮葡萄球菌分离株的<10 kDa组分。通过酶联免疫吸附测定法（ELISA）测定经poly I:C和<10 kDa组分刺激的HaCaT角质形成细胞中TNFα的产生。在细菌生长过程中，通过流式细胞术、蛋白质印迹法和电喷雾电离质谱法测定分离株细胞膜及<10 kDa组分中的LTA。评估尿苷二磷酸葡萄糖基转移酶P（ugtP）、LTA合成酶A（ltaA）和LTA合成酶S（ltaS）的表达水平。
发现了两类分离株群体：一类抑制TNFα产生（TNFα抑制株），另一类不抑制TNFα产生（TNFα非抑制株）。与TNFα非抑制株的细胞相比，TNFα抑制株的细胞在细胞膜中的LTA含量更少（P < 0.05）。同样，在TNFα抑制株的上清液中检测到LTA，而TNFα非抑制株的上清液中未检测到。在细菌生长过程中，发现1850I（TNFα抑制株）和37HS（TNFα非抑制株）分离株中ugtP和ltaA基因的表达水平较高。然而，ltaS基因在37HS分离株中的表达水平较低（P < 0.05）。
TNFα抑制株由于LTA合成基因的高表达而释放LTA。相比之下，TNFα非抑制株由于ltaS基因的低表达而不释放LTA。
