Radolf J D, Arndt L L, Akins D R, Curetty L L, Levi M E, Shen Y, Davis L S, Norgard M V
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235.
J Immunol. 1995 Mar 15;154(6):2866-77.
The observation that the major membrane immunogens of the spirochetal pathogens. Treponema pallidum and Borrelia burgdorferi are lipoproteins prompted studies to investigate macrophage activation by the 47-kDa lipoprotein of T. pallidum and the acylated outer surface protein A (OspA) of B. burgdorferi. Both lipoproteins induced the synthesis of biologically active TNF-alpha and chloramphenicol acetyltransferase in a murine macrophage cell line transfected with a chloramphenicol acetyltransferase reporter gene controlled by a TNF promoter (TB2 cells). Nonacylated forms of these polypeptides did not induce cell activation. Comparison between purified OspA and B. burgdorferi cellular lipids revealed that the former was the more potent inducer of TNF-alpha. Synthetic lipohexapeptides corresponding to the N-termini of the 47-kDa lipoprotein of T. pallidum and OspA also activated TB2 cells in a dose-dependent fashion, whereas the nonlipidated hexapeptides were without effect, further underscoring the importance of protein acylation to cell activation. Among several lines of evidence supporting that macrophage stimulation by LPS and lipopeptides proceeds via different mechanisms, the most notable was that lipopeptides activated peritoneal macrophages from LPS-nonresponsive C3H/HeJ mice. The potential for spirochetal lipoproteins to function as general macrophage activators was demonstrated by the ability of the synthetic analogues to induce IL-1 beta, IL-6, and IL-12, in addition to TNF, in murine and/or human macrophages. Our findings indicate that spirochetal lipoproteins may be important immunomodulators in syphilis and Lyme disease and that the synthetic lipopeptides will be useful surrogates for studying immune mechanisms operative in the two spirochetal diseases.
梅毒螺旋体病原体梅毒螺旋体和伯氏疏螺旋体的主要膜免疫原是脂蛋白，这一观察结果促使人们开展研究，以调查梅毒螺旋体47 kDa脂蛋白和伯氏疏螺旋体酰化外表面蛋白A（OspA）对巨噬细胞的激活作用。在转染了由肿瘤坏死因子（TNF）启动子控制的氯霉素乙酰转移酶报告基因的小鼠巨噬细胞系（TB2细胞）中，这两种脂蛋白均诱导了生物活性TNF-α和氯霉素乙酰转移酶的合成。这些多肽的非酰化形式未诱导细胞激活。纯化的OspA与伯氏疏螺旋体细胞脂质之间的比较显示，前者是更强效的TNF-α诱导剂。与梅毒螺旋体47 kDa脂蛋白和OspA的N端相对应的合成脂六肽也以剂量依赖的方式激活了TB2细胞，而非脂质化的六肽则无作用，这进一步强调了蛋白质酰化对细胞激活的重要性。在支持脂多糖（LPS）和脂肽激活巨噬细胞通过不同机制进行的几条证据中，最值得注意的是脂肽激活了来自对LPS无反应的C3H/HeJ小鼠的腹腔巨噬细胞。合成类似物在小鼠和/或人类巨噬细胞中除了诱导TNF外，还能诱导白细胞介素-1β（IL-1β）、白细胞介素-6（IL-6）和白细胞介素-12（IL-12），这证明了螺旋体脂蛋白作为一般巨噬细胞激活剂的潜力。我们的研究结果表明，螺旋体脂蛋白可能是梅毒和莱姆病中重要的免疫调节剂，并且合成脂肽将是研究这两种螺旋体疾病中免疫机制的有用替代物。
