Consequences of chronic Interferon-gamma expression on the host

慢性干扰素-γ表达对宿主的后果

• 批准号: 9556229
• 负责人: Howard Young
• 金额: $ 142万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9556229
• 关键词: 3' Untranslated Regions; Adaptive Immune System; Affect; Antibody Formation; Antibody Response; Antigens; Aplastic Anemia; Architecture; Autoimmunity; B-Lymphocytes; Behavior; Belief; Biliary; Bioinformatics; Biological; Biology; CD8-Positive T-Lymphocytes; Cells; Cholangitis; Chromatin; Chronic; Communicable Diseases; Complex; Controlled Study; Cytokine Gene; DNA; DNA Methylation; Data; Defect; Development; Disease; Effector Cell; Etiology; Evolution; Exhibits; Female; Frequencies; Gene Expression; Gene Structure; Genetic; Goals; Hematopoietic stem cells; Homeostasis; Human; IgG1; Immune; Immune response; Immune system; Immunoglobulin M; Inbred BALB C Mice; Infection; Inflammation; Inflammatory; Interferon Type II; Knockout Mice; Laboratories; Laboratory Study; Liver; Long-Term Effects; Lupus; Lymphocyte; Malignant Neoplasms; Mediation; Messenger RNA; Molecular; Molecular Conformation; Mouse Strains; Mus; Phenotype; Play; Population; Post-Transcriptional Regulation; RNA; Regulation; Regulatory Element; Renal carcinoma; Resistance; Role; Sex Bias; Spleen; Structure; Symptoms; Systems Biology; T-Lymphocyte; Thymus Gland; Untranslated RNA; Whole Organism; Wild Type Mouse; Woman; Work; base; cytokine; heart function; human disease; lupus-like; lymph nodes; mRNA Instability; mRNA Stability; mouse model; response; trafficking; transcription factor

We are utilizing a mouse model of chronic IFN-gamma expression to determine the biological consequences to the host and the relevance of this phenotype to human disease. We have used a bioinformatics approach to identify conserved regions of the 3' untranslated portion of the interferon-gamma mRNA. It is believed that these conserved regions represent important regulatory elements in the gene structure, as there would be no inherent reason for conservation through evolution unless the non-coding regions of the mRNA provided some evolutionary advantage. Based on this analysis, we targeted a 160-bp region of the murine interferon-gamma 3' untranslated region for deletion as this region is rich in AUUA sequences, and such regions have been previously shown to be important in the regulation of cytokine gene mRNA instability. The knockout (KO) mouse has been successfully created on the C57 BL/6 genetic background and our data indicates that this mouse produces significantly more interferon-gamma at a basal level and upon stimulation as compared to the wild-type mouse. Furthermore, the architecture of lymph nodes, spleen, and thymus is disrupted and the liver exhibits signs of chronic inflammation. T cell homeostasis has been disrupted as increased CD4+ and CD8+ T cells are present and the T reg cells in the mouse have more potent suppressor activity. There is also an increased TH1 response and a decreased TH2 response to antigenic stimulation. The B cell population is also altered and baseline antibody production is skewed. B cells are also observed in the thymus at increased frequency, thus indicating that IFN-gamma may alter B cell trafficking. In addition to the phenotypic consequences, the B cell response to antigen is also disrupted as increased IgM and Ig2a ab responses are seen with a decrease in the IgG1 response. Strong anti-DNA and anti-nuclear antigen antibody responses are also observed suggesting that chronic IFN-gamma expression may play a role in the development of lupus. The female mice also develop primary biliary cholangitis, a disease that has no known etiology. This is the first mouse model to recapitulate the human disease with respect to sex bias as 90% of the human cases are in women. Curiously, lupus-like and PBC symptoms are not seen in the Balb/c mouse, where the 160-bp deletion has also been crossed onto that genetic background. These mice have increased spleen sizes and an apparent defect in lymphocyte trafficking to the lymph nodes. This results in a phenotype very similar to aplastic anemia. These effects appear to be a direct consequence of interferon-gamma inhibition of hematopoietic progenitors in this mouse strain. In addition, the Balb/c mice with the deletion appear to be more resistant to challenge with the renal carcinoma line RENCA. In summary, our approach towards elucidating the multiple mechanisms involved in the biology of interferon-gamma demonstrates the complexity by which interferon-gamma gene expression alters host homeostasis. In addeition to these effects, we have now observed that chronic IFN-g expression affects mouse behavior and heart function. Thus, we now have developed a mouse model for understanding and elucidating the systems biology effects of long term chronic IFN-gamma gene expression, resulting in chronic inflammation in the host.

我们正在利用慢性 IFN-γ 表达的小鼠模型来确定对宿主的生物学后果以及该表型与人类疾病的相关性。我们使用生物信息学方法来鉴定干扰素-γ mRNA 3'非翻译部分的保守区域。人们相信，这些保守区域代表了基因结构中的重要调控元件，因为除非 mRNA 的非编码区域提供了一些进化优势，否则在进化过程中不会存在保守的内在原因。基于此分析，我们针对鼠干扰素-γ 3'非翻译区的 160 bp 区域进行了删除，因为该区域富含 AUUA 序列，并且此类区域先前已被证明在细胞因子基因 mRNA 的调节中很重要不稳定。敲除 (KO) 小鼠已在 C57 BL/6 遗传背景上成功创建，我们的数据表明，与野生型小鼠相比，该小鼠在基础水平和刺激后产生显着更多的干扰素-γ。此外，淋巴结、脾脏和胸腺的结构被破坏，肝脏表现出慢性炎症的迹象。随着 CD4+ 和 CD8+ T 细胞的增加，T 细胞稳态已被破坏，并且小鼠中的 T reg 细胞具有更有效的抑制活性。对抗原刺激的 TH1 反应增加，TH2 反应减少。 B 细胞群也发生改变，基线抗体产生发生偏差。在胸腺中也观察到 B 细胞的频率增加，因此表明 IFN-γ 可能会改变 B 细胞的运输。除了表型后果外，B 细胞对抗原的反应也被破坏，因为 IgM 和 Ig2a ab 反应增加，而 IgG1 反应减少。还观察到强烈的抗 DNA 和抗核抗原抗体反应，表明慢性 IFN-γ 表达可能在狼疮的发展中发挥作用。雌性小鼠还会患上原发性胆汁性胆管炎，这是一种病因不明的疾病。这是第一个在性别偏见方面重现人类疾病的小鼠模型，因为 90% 的人类病例都是女性。奇怪的是，在 Balb/c 小鼠中没有发现狼疮样和 PBC 症状，其中 160 bp 缺失也已与该遗传背景交叉。这些小鼠的脾脏尺寸增大，淋巴细胞运输至淋巴结的能力明显缺陷。这导致与再生障碍性贫血非常相似的表型。这些效应似乎是该小鼠品系中干扰素-γ抑制造血祖细胞的直接结果。此外，具有缺失的Balb/c小鼠似乎对肾癌系RENCA的攻击具有更强的抵抗力。总之，我们阐明干扰素γ生物学涉及的多种机制的方法证明了干扰素γ基因表达改变宿主稳态的复杂性。除了这些影响之外，我们现在还观察到慢性 IFN-g 表达会影响小鼠的行为和心脏功能。因此，我们现在开发了一种小鼠模型，用于理解和阐明长期慢性 IFN-γ 基因表达导致宿主慢性炎症的系统生物学效应。