高血壓導致多種疾病，例如心血管疾病、慢性腎臟疾病和認知障礙。腎臟為高血壓所導致終端損傷的主要器官，此外也會傾向於影響腸道屏障。已有許多研究表明自發性高血壓大鼠（SHR）模型能模擬人類原發性高血壓，其中SHR-A3和SHR-B2品系老鼠對於腎損傷分別具有易感性和抵抗力，而在遺傳學研究中發現，是由於IgH和Stim1基因座所導致此易感性。而在初步的研究中發現除了SHR-A3和SHR-B2基因的自然變異，腸道細菌也在高血壓腎臟疾病的發病機制中扮演重要的角色。因著高血壓，腸道共生細菌藉由從黏膜層表面轉移到固有層並成為宿主的病原體。因此，我們假設細菌抗原作為分子模擬物，促使宿主產生與自體抗原結合的抗體。有需要藉由尋找引發自體抗體的細菌抗原以闡明在高血壓腎損傷中腸道細菌如何影響宿主免疫反應。在這項研究中透過高血壓腎臟損傷的動物模型，解析細菌抗原所引發的自體免疫反應。我們的實驗室已成功開發涵蓋約4800種蛋白質的全基因大腸桿菌蛋白質體微陣列晶片，能夠系統且全面性分析細菌抗原-抗體相互作用。使用大腸桿菌蛋白質晶片，從易感受性SHR-A3和具有抵抗性的SHR-B2大鼠，年齡為18週和40週收集而來的血清進行探測，並藉由具有螢光標記的二抗IgG和IgM抗體檢測抗原。藉由在實驗組和控制組有訊號亮度差異的蛋白質找出可能誘發自體抗體的抗原。為了找到可能誘發自體抗體的抗原，實驗組SHR-A3 40週分別和不同的控制組SHR-B2、SHR-A3（IgH.B2）和SHR-A3（Stim1.B2）比較。從這些比較中得出的聯集是可能引起高血壓腎損傷的潛在病原體抗原，發現了87個IgG和106個IgM相關致病抗原。而上述比較的交集被視為最顯著可能致病抗原有兩個最顯著可能的IgG（FliG，SecA）和八個IgM（IspE，HscB，HsdM，UxuR，SecA，HtpG，Smg，CyaY）的可能致病抗原。將87個IgG和106個IgM的聯集結果各自做富集分析，結果顯示在某些類別有共同顯著的表現。例如磷酸吡哆醛結合位和磷酸吡哆醛依賴型脫羧酶在功能域有共同的顯著表現。特定蛋白質結合和蛋白質結合在分子功能有共同的顯著表現。細胞質液在細胞組件有共同的顯著表現。麩胺酸代謝過程在生物途徑有共同的顯著表現。然而，當87個IgG和106個IgM的聯集結果互相比較卻發現只有12個抗原有交疊，表示IgG和IgM自體抗體幾乎由不同的抗原誘發。這個研究對於在高血壓腎臟疾病中細菌抗原所涉及的作用提供重要的見解。

High blood pressure can cause various conditions such as cardiovascular disease, chronic kidney disease, and cognitive impairment. The kidneys are the major target for end-organ damage due to hypertension, which also tends to affect the gut barrier. Spontaneous Hypertensive Rat (SHR) models with high blood pressure have been studied which acts as an analog to essential hypertension in humans. SHR-A3 and SHR-B2 strains have high blood pressure which show susceptibility and resistance to renal injury respectively. Genetic studies found that there are two loci, IgH and Stim1, which are responsible for the susceptibility to renal injury. Preliminary studies showed that apart from natural variation in SHR-A3 and SHR-B2 genes, gut bacteria also played an essential role in pathogenesis of the hypertensive kidney disease. Due to hypertension, the gut commensal bacteria translocated from gut lumen to lamina propria and became pathogenic to the host. Thus, we hypothesized that bacterial antigens, which act as molecular mimics, would make the host produce autoantibodies which bind to their own antigens. Identification of bacterial antigens which trigger possible autoantibodies is needed to elucidate the role of gut bacteria in the host immune response for hypertensive renal injury. This study deciphered bacterial antigens triggering an autoimmune response in hypertensive animal models with kidney injury. Our lab has successfully developed a method for the systematical and comprehensive analysis of bacterial antigen-antibody interaction through a genome-wide E. coli proteome microarray, which covers ~4,800 proteins. Serum collected at 18 weeks and 40 weeks of age from injury susceptible (SHR-A3) and injury resistant (SHR-B2) rats were probed with E. coli proteome chips. The antigens were detected by fluorescently tagged secondary IgG and IgM antibodies. The proteins with outstanding signals from the experimental group compared to the control groups were identified to be the potential antigens triggering possible autoantibodies. For finding the antigens which may trigger possible autoantibodies, SHR-A3 40 weeks was regarded as the experimental group, and was compared with different control groups, SHR-B2, SHR-A3(IgH.B2), and SHR-A3(Stim1.B2). The union from those comparisons are the potential pathogenic antigens which may cause hypertensive kidney injury. There were 87 IgG and 106 IgM relevant pathogenic antigens found from the union list. The results of the intersection of the above comparisons are the most significant antigens. There were two most significant IgG antigens (FliG and SecA), and eight IgM antigens (IspE, HscB, HsdM, UxuR, SecA, HtpG, Smg, and CyaY). The enrichment results of the unions for the antigens which trigger IgG and IgM showed that there were some commonalities. Pyridoxal-phosphate binding site and pyridoxal phosphate-dependent decarboxylase, in the category protein domain; identical protein binding and protein binding, in the category molecular function; cytosol, in the category cellular component; and glutamate metabolic process, in the category biological process were the commonalities from the comparison between the enrichment results. However, when the 87 IgG and 106 IgM potential antigens were compared, only 12 antigens overlapped, indicating that IgG and IgM possible autoantibodies were triggered mostly by different antigens. The study gave an important insight in to the role of bacterial antigens involved in hypertensive kidney disease.

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