Immune regulation by the inhibitory IgG receptor related to the susceptibility of periodontitis

人低亲和力Fc受体Ⅱ B b（FcγRIIb）是一种IgG受体，通过免疫复合物与B细胞受体（BCR）交联，抑制B淋巴细胞的活化。FcγRIIb的这种功能对于抗体产生的负调节至关重要。我们前期的研究已经证实Fcγ RIIB-I232 T基因多态性与牙周炎显著相关。在这项研究中，我们研究的可能性，IgG抗体反应牙周致病菌牙龈卟啉单胞菌（P.gingivalis）之间的不同基因型的牙周炎患者是不同的。采用基因组DNA直接测序法对47例牙周炎患者进行Fcγ RIIB-I232 T基因分型。测定了牙龈卟啉单胞菌超声处理物、重组40-kDa外膜蛋白（OMP）和200 kDa抗原蛋白（AP）的血清非特异性总IgG和特异性IgG亚类水平。FcγRIIB-232 T载体显示对P.gin的显著较低的IgG 2应答 ...更多信息 givalis 40-kDa OMP与非携带者相比差异有统计学意义（P<0.05）。在特异性IgG和IgG 1水平上也观察到FcγRIIB-232 T载体的较低应答，但无统计学显著性。FcγRIIB-232 T携带者和非携带者对牙龈卟啉单胞菌超声处理物或200-kDa AP的抗体应答无显著差异。在FcγRIIB-232 T非携带者中，有一个亚组的患者显示出高水平的IgG 2应答，与高平均探测深度一致。相比之下，所有FcγRIIB-232 T携带者均显示较低水平的IgG 2应答。结果表明，FcγRIIB-232 T等位基因与牙周炎的发生有关，可能与牙周炎患者对牙龈卟啉单胞菌的抗体应答水平较低有关。牙周炎患者的B淋巴细胞上FcγRIIb的表达水平低于对照组。这可能是牙周炎发病过程中抑制B淋巴细胞过度活化效果不佳的原因之一。FcγRIIb在牙周炎牙龈组织中也有表达。少

Human low affinity Fc receptor IIb (FcγRIIb) is one of IgG receptors and suppress the activation of B lymphocytes through cross-linking with B cell receptor (BCR) via immune-complexes. This function of FcγRIIb is essential for the negative regulation of antibody productions. Our previous study has demonstrated the gene polymorphism FcγRIIB-I232T to be significantly associated with periodontitis. In this study, we examined the possibility that IgG antibody responses to periodontopathic bacteria Porphyromonas gingivalis (P.gingivalis) are different between periodontitis patients with different genotypes. Forty-seven patients with periodontitis were genotyped for FcγRIIB-I232T with the direct sequencing of genome DNA. Serum levels of nonspecific total IgG and specific IgG subclasses for the sonicate of P.gingivalis, the recombinant 40-kDa outer membrane protein (OMP) and 200kDa antigenic protein (AP) were determined. FcγRIIB-232T carrier revealed significantly lower IgG2 response to P.gin … More givalis 40-kDa OMP compared to noncarrier (P<0.05). Lower responses of FcγRIIB-232T carrier were also observed in specific IgG and IgG1 levels which were not statistically significant. No significant difference of antibody response to P.gingivalis sonicate or 200-kDa AP was observed between FcγRIIB-232T carrier and noncarrier. In FcγRIIB-232T noncarrier, there was a subgroup of patients showing high levels of IgG2 response in concert with the high average of probing depth. In contrast, all FcγRIIB-232T carriers revealed lower levels of IgG2 response. These results suggest that the association of FcγRIIB-232T allele with periodontitis might be attributed to the lower level of antibody response to P.gingivalis.We investigated the expression of FcγRIIb in peripheral blood leukocytes and gingiva from periodontitis patients. Expression levels of FcγRIIb on B lymphocytes were lower in patients with periodontitis compared to controls. This might be a cause of less effective inhibition of overactivation of B lymphocytes in the pathogenesis of periodontitis. Expression of FcγRIIb was also confirmed in human gingiva with periodontitis. Less