Cutler C W, Arnold R R, Schenkein H A
Department of Stomatology, University of Texas at Houston 77030.
J Immunol. 1993 Dec 15;151(12):7016-29.
In the face of an apparently competent immune response to Porphyromonas gingivalis, it is unclear how P. gingivalis evades the immune response and persists in human periodontitis. Particularly germane may be its ability to resist phagocytosis by degrading and not binding serum opsonins. In our study, the resistance by invasive (W83 and A7436) and noninvasive (ATCC 33277) P. gingivalis strains to phagocytosis by human neutrophils was compared with their C3- and IgG-proteolytic activity. The ability of opsonic human serum antibody to inhibit C3 proteolysis was also evaluated. Our results indicate that the more phagocytosis-resistant invasive strains accumulate less 125I-C3 than the noninvasive strain; moreover, invasive strains degrade complement C3 in a dose-dependent manner, inhibitable by rabbit antiserum or adult periodontitis serum. Opsonization and C3 accumulation on strain A7436 were both facilitated by pretreatment with rabbit antiserum, certain adult periodontitis sera, protease inhibitors (p-chloromercuriphenylsulfonic acid, N alpha-p-tosyl-L-lysine chloromethyl ketone, diisopropylfluorophosphate), heat (60 degrees C, 15 min), and were Mg2+ dependent. The sera from 13 human subjects with or without periodontitis were assayed for antibody titers to P. gingivalis (ELISA units), opsonic activity (% of PMN engaged in phagocytosis) and enhancement of C3 accumulation. Statistically significant associations were observed between % of PMN engaged in phagocytosis and % C3 accumulation, between % of PMN engaged in phagocytosis and ELISA units and between % C3 accumulation and ELISA units. Degradation of purified rabbit IgG, but not specific antibody-containing rabbit IgG by P. gingivalis A7436 was observed, and was inhibited by diisopropyl fluorophosphate (DFP) or cold (2 degrees C). Our data suggest that C3 and IgG cleavage by P. gingivalis proteases are inhibitable by antibody and are contributory factors in, but are not the sole determinants of, phagocytosis resistance.
面对针对牙龈卟啉单胞菌的明显有效的免疫反应，尚不清楚牙龈卟啉单胞菌如何逃避免疫反应并在人类牙周炎中持续存在。其通过降解而非结合血清调理素来抵抗吞噬作用的能力可能尤为关键。在我们的研究中，将侵袭性（W83和A7436）和非侵袭性（ATCC 33277）牙龈卟啉单胞菌菌株对人中性粒细胞吞噬作用的抵抗力与其C3和IgG蛋白水解活性进行了比较。还评估了调理人血清抗体抑制C3蛋白水解的能力。我们的结果表明，与非侵袭性菌株相比，更具抗吞噬作用的侵袭性菌株积累的125I-C3更少；此外，侵袭性菌株以剂量依赖的方式降解补体C3，兔抗血清或成人牙周炎血清可抑制这种降解。用兔抗血清、某些成人牙周炎血清、蛋白酶抑制剂（对氯汞苯磺酸、Nα-对甲苯磺酰-L-赖氨酸氯甲基酮、二异丙基氟磷酸）、加热（60℃，15分钟）预处理均促进了菌株A7436上的调理作用和C3积累，且这些过程依赖Mg2+。检测了13名有或无牙周炎的人类受试者血清中针对牙龈卟啉单胞菌的抗体滴度（ELISA单位）、调理活性（参与吞噬作用的PMN的百分比）和C3积累的增强情况。观察到参与吞噬作用的PMN百分比与C3积累百分比之间、参与吞噬作用的PMN百分比与ELISA单位之间以及C3积累百分比与ELISA单位之间存在统计学上的显著关联。观察到牙龈卟啉单胞菌A7436可降解纯化的兔IgG，但不能降解含特异性抗体的兔IgG，二异丙基氟磷酸（DFP）或低温（2℃）可抑制这种降解。我们的数据表明，牙龈卟啉单胞菌蛋白酶对C3和IgG的裂解可被抗体抑制，是抗吞噬作用的促成因素，但不是唯一决定因素。
