Studies of Primary Immunodeficiency Diseases

项目1：高IgM综合征的研究。高IgM综合征可由几种影响B(和T)细胞功能的分子缺陷引起。最好的描述形式是X-连锁高IgM(XHIM)综合征，它是由于肿瘤坏死因子受体超家族成员CD40L的突变引起的。在以前的研究中，我们已经表明，这种形式的高IgM综合征患者除了众所周知的B细胞分化缺陷和缺乏免疫球蛋白/IgA产生外，还有一种显著的T细胞缺陷。这包括T细胞成熟缺陷，这是由于CD40L刺激APC的减少导致T细胞共刺激分子的表达减少，以及APC产生IL-12的能力下降所致。这种T细胞缺陷可能是XHIM患者发生机会性感染以及尽管接受IVIG替代治疗但存活率下降的一个可能原因。在此基础上，我们现在已经开始了用免疫公司的重组CD40L-三聚体治疗XHIM患者的研究。这项治疗研究的现状如下：1)NIAID IRB已经编写并批准了该方案；患者将接受越来越大剂量的CD40L-三聚体皮下注射，然后研究Ig水平、抗体反应、细胞因子产生能力(特别是IL-12)和淋巴细胞表型；2)已经开始治疗的两名患者，已经确定CD40L不会引起严重的副作用；然而，在患者中性粒细胞边际增加和激活标记表达增加的情况下，观察到生物学活性；3)已经联系了大量的患者，适合研究的患者正在被顺序接纳，以获得所需的20-25名研究人群；4)已经调动了NIAID临床计划的资源来完成这项非正在进行的研究。第二种形式的高IgM综合征是另一种与外胚层发育不良相关的X连锁形式，这种遗传疾病现在被认为是由于(EDA)-胞浆蛋白受体(DL)信号通路中的蛋白质突变所致；因此，可能是同时参与CD40和DL受体信号传递的分子的突变导致了这种形式的X连锁高IgM综合征。为了探索这种可能性，我们对X连锁高IgM综合征和ED患者进行了定位和入院治疗，并首先表明他们在通过CD40发出信号时也不产生IL-12，从而表明T细胞和B细胞中这一途径存在缺陷。然而，这些患者与“普通”XHIM患者的不同之处在于，他们表现出正常的T细胞成熟，因此产生细胞因子的能力也正常。这意味着CD40信号的缺陷并不影响共刺激分子的表达。在进一步的研究中，我们已经证明这些患者不会在CD40信号转导时激活核因子-kB，从而定位于核因子-kB激活的上游的CD40信号缺陷。项目2：共同变量免疫缺陷(CVI)患者研究。在对原发免疫缺陷患者正在进行的临床研究中，我们发现了一种新型细菌制剂，可导致Bruton‘s X连锁无丙种球蛋白血症患者的感染。特别是，我们描述了两名患有后一种疾病的患者，他们的菌血症和皮肤/骨骼感染与16S信使核糖核酸分析鉴定为一种细菌密切相关，但不完全相同(因此将其命名为类Flexispira，Flo)，而与螺杆菌的亲缘关系更远。该微生物需要微氧条件，补充H2气体才能生长，并可靠地被吖啶橙染色。与幽门螺杆菌感染一样，Flo感染的病灶1例位于四肢的血管或淋巴管，另1例位于四肢的皮肤和邻近的骨骼。在这两个患者中，都需要延长静脉注射抗生素治疗以清除感染。XLA患者对Flo感染的易感性与XLA与严重的B细胞(体液)免疫缺陷有关，因此患者难以发生血管内或淋巴内感染。这些发现阐明了人类Flo感染的性质，并为其检测和治疗指明了方向。

Project 1: Studies of the hyper-IgM syndrome. The hyper-IgM syndrome can arise from several molecular defects affecting B (and T) cell function. The best described form is X-linked hyper-IgM (XHIM) syndrome which is due to a mutation in the TNF-receptor superfamily member CD40L. In previous studies we have shown that patients with this form of hyper-IgM syndrome manifest, in addition to their well-known defect in B cell differentiation and lack of IgG/IgA production, a significant T cell defect. This consists of a defect in T cell maturation resulting from decreased expression of T cell co-stimulatory molecules consequent to reduced CD40L stimulation of APC's and decreased capacity of APC's to produce IL-12. This T cell defect is a likely cause of the occurrence of opportunistic infection in XHIM patients and their decreased survival despite IVIG replacement therapy. On this basis we have now initiated study of the treatment of patients with XHIM with recombinant CD40L-trimer obtained from the Immunex Corporation. The status of this treatment study is as follows: 1) The protocol has been written and approved by the NIAID IRB; patients are to be administered increasing doses of CD40L-trimer subcutaneously and then studied with respect to Ig levels, antibody responses, cytokine production capactiy (particularly IL-12) and lymphocyte phenotyping; 2) Two patients have been begun on treatment and it has been established that CD40L does not induce severe side efects; however, biologic activity is observed in that patient neutrophils show increased margination and expression of activation markers; 3) A large pool of patients have been contacted and patients suitable for study are being admitted sequentially to obtain the desired study population of 20-25 patients; 4) The resources of the NIAID clinical program have been mobilized to accomplish this non on-going study. A second form of hyper-IgM syndrome is another X-linked form associated with ectodermal dysplasia, a genetic disorder now known to be due to a mutation in a protein in the ectoplasm in (Eda)-ectoplasmin receptor (DL) signaling pathway (which is also a TNF-receptor superfamily pathway); thus, it is possible that a mutation in a molecule that is involved in both CD40 and DL receptor signaling is responsible for this form of X-linked hyper-IgM syndrome. To explore this possibility, we have located and admitted patients with X-linked hyper-IgM syndrome and ED and have shown first that they also do not produce IL-12 upon signaling via CD40, thus demonstrating a defect in this pathway in T cells as well as B cells. However, these patients differ from those with "ordinary" XHIM in that they manifest normal T cell maturation and thus normal capacity to produce cytokines. This implies that the defect in CD40 signaling does not effect expression of co-stimulatory molecules. In further studies we have shown that these patients do not activate NF-kB upon CD40 signaling thereby localizing the CD40 signaling defect upstream of NF-kB activation. Project 2: Studies of Patients with Common Variable Immunodeficiency (CVI). In on-going clinical studies of patients with primary immunodeficiency we have identified a new type of bacterial agent causing infection in patients with Bruton's X-linked agammaglobulinemia. In particular, we described two patients with the latter disease who had bacteremia and skin/bone infection close to an organism identified by 16S mRNA analysis as a bacterium closely related to but not identical with "Flexispira" rappini (and thus designated a Flexispira-like organism, FLO) and more distantly related to Helicobacter species. The organism required microaerobic conditions, supplemental H2 gas for growth and was reliably stained with acridine-orange. In common with Helicobacter cinaedi infections, the focus of the FLO infection was in one case in the blood vessels or lymphatics of an extremity, and in the other case in the skin and adjacent bone of an extremity. In both patients, prolonged IV antibiotic therapy was necessary to clear the infection. The susceptibility of XLA patients to FLO infection apppears related to the fact that XLA is associated with severe B cell (humoral) immunodeficiency and thus patients have difficulty with intravascular or intralymphatic infection. These findings elucidate the nature of FLO infections in humans and point the way to their detection and treatment.