The Role Of Cytokines In The Developing Immune System

我们假设环境暴露会改变免疫系统发育中的特定事件。诸如上呼吸道感染等疾病会使新生儿更容易受到以后感染的影响。我们与杜克大学的Jane Blood-Siegfried博士合作，设计了一种上呼吸道感染和细菌性败血症的双重感染模型，在近亲繁殖的大鼠品系中诱导类似sid的病理。使用这个模型，我们已经建立了一个双重感染损伤的关键窗口，导致类似小岛屿发展中国家的死亡。流感后2天给予流感和内毒素的新生大鼠幼崽，在内毒素剂量为2 mg/kg、0.5 mg/kg和0.2 mg/kg后7-23小时内死亡率为73%。0.05 mg/kg内毒素组无死亡病例，流感对照组和单纯内毒素对照组无死亡病例。亚伯拉罕·尼斯卡（Abraham Nyska）博士对LEP的评估表明，对照组幼崽没有明显的病理发现。在受到这两种药物攻击的动物中，尸检时的具体肉眼和显微镜变化与SIDS婴儿尸检时发现的变化相似。0.2 mg/kg内毒素剂量的幼崽出现肺瘀点和出血，脾脏轻度充血和其他退行性病变，与人类小岛屿发展中国家死亡的病理结果一致。Nyskas博士的评估表明，该模型中的死亡率与系统性事件有关，而不是特定的肺损伤。与仅内毒素或仅raiv对照相比，双感染大鼠幼崽的血清干扰素γ水平和脾脏白细胞群存在显著差异。在死亡率增加的关键时期，脾脏中巨噬细胞激活增加和自然杀伤细胞数量增加表明TH-1型免疫反应过度。一份详细描述基线免疫参数和病变病理的手稿已提交发表。有充分证据表明，自身免疫性疾病的易感性在很大程度上取决于特定主要组织相容性复合体（MHC）基因型的存在，然而，疾病症状的发展似乎也需要关键的环境因素，如细菌或病毒感染或化学物质暴露。我们正在研究产前和成人暴露于环境因素在自身免疫发展中的作用。虽然发育暴露的影响可能是至关重要的，但这些影响尚未在适当的易发生自身免疫功能障碍的啮齿动物模型中进行全面研究。我们已经开始研究产前暴露于内分泌干扰化学物质对自身免疫倾向的啮齿动物的产后免疫后果。我们研究了妊娠期暴露于TCDD的MRL/lpr自身免疫易感小鼠自身免疫疾病发生率增加和/或恶化的可能性。MRL/lpr小鼠表现出严重的肾坏死（肾小球肾炎），类似于在人类系统性红斑狼疮患者中观察到的情况，雌性通常在大约14-16周龄时出现针对核蛋白颗粒的循环自身抗体和随后的肾补体-抗体免疫复合物，而雄性在20-22周龄时。通过血清ssDNA自身抗体的定量、尿蛋白水平和肾脏组织病理学来评估雌性和雄性小鼠自身免疫的严重程度，以确定是否存在不同的化学诱导作用。雌性小鼠的结果显示，与对照组相比，分别在6、10和12周龄时，暴露于tcdd的动物的抗ssdna、尿蛋白和肾脏异常明显呈剂量依赖性增加。在8、10和12周龄接触二恶英的雄性小鼠中也发现了类似的结果。

We hypothesized that specific events in the developing immune system are altered by environmental exposures. Insults such as upper respiratory tract infections could make neonates more susceptible to the effects of later infections. In collaboration with Dr. Jane Blood-Siegfried at Duke University, we have designed a dual infection model of upper respiratory tract infection and bacterial sepsis to induce a SIDS-like pathology in an inbred rat strain. Using this model, we have established a critical window of dual infectious insults, which result in a SIDS-like death. Neonatal rat pups given influenza and endotoxin two days post influenza had a 73% mortality rate within 7-23 hours post endotoxin for doses of 2 mg/kg, 0.5 mg/kg and 0.2 mg/kg. There were no deaths with 0.05 mg/kg endotoxin and no mortality in the influenza or endotoxin only control groups. Evaluation by Dr. Abraham Nyska, LEP indicates that there were no gross pathology findings in the control pups. In animals challenged with both agents, specific gross and microscopic changes on necropsy were similar to those found on autopsy of SIDS infants. Pups dosed with 0.2 mg/kg endotoxin had petechiae and hemorrhage in the lungs, mild congestion of the spleen and other degenerative lesions consistent with the pathological findings in human SIDS deaths. Dr. Nyskas evaluation suggests that mortality in this model is related to a systemic event rather than specific lung damage. Significant differences were observed in serum interferon gamma levels and splenic leukocyte populations in dual-infected rat pups as compared to endotoxin-only or RAIV-only controls. Increased macrophage activation and increased numbers of natural killer cells in the spleen during the critical period for increased mortality suggest an exaggerated TH-1 type immune response. A manuscript detailing the baseline immune parameters and pathology of the lesion has been submitted for publication. It is well documented that autoimmune disease susceptibility is largely dependent upon the presence of particular major histocompatibility complex (MHC) genotypes, however, development of disease symptoms also appears to require critical environmental factors, such as bacterial or viral infections or chemical exposure. We are examining the role of prenatal and adult exposures to environmental agents in the development of autoimmunity. Although the effects of developmental exposure may be of critical importance, these effects have not been comprehensively studied in appropriate rodent models predisposed to autoimmune dysfunction. We have begun to examine postnatal immune consequences of prenatal exposure to endocrine disrupting chemical in autoimmune-prone rodents. We have examined the potential for increased incidence and/or exacerbation of autoimmune disease in MRL/lpr autoimmune-prone mice exposed during gestation to TCDD. MRL/lpr mice exhibit severe renal necrosis (glomerulonephritis) similar to that observed in human patients with systemic lupus erythematosus, with females normally presenting circulating autoantibodies against nucleoprotein particles and subsequent renal complement-antibody immune complexes at approximately 14-16 weeks of age vs. males at 20-22 weeks. Severity of autoimmunity as assessed via quantitation of serum autoantibodies to ssDNA, urinary protein levels, and renal histopathology was compared in female versus male mice to determine if differential chemical-induced effects were present. Results in female mice indicated a significant, dose-dependent increase in anti-ssDNA, urinary protein, and renal abnormalities in TCDD-exposed animals as compared to controls at six, ten, and 12 weeks of age, respectively. Similar results were noted in dioxin-exposed males at eight, ten and 12 weeks of age.