Bolton Warren Kline, Chen Lanlin, Hellmark Thomas, Wieslander Jörgen, Fox Jay W
Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908-0133, USA.
J Am Soc Nephrol. 2005 Sep;16(9):2657-66. doi: 10.1681/ASN.2004100823. Epub 2005 Jul 27.
An amino-terminal region of alpha3 chain of type IV collagen noncollagenous domain [alpha3(IV)NC1] that induces experimental autoimmune glomerulonephritis (EAG) in rats has been identified. Only recombinant antigens that contain a nine-amino acid (AA) span of alpha3(IV)NC1, consistent with a T cell epitope, could induce EAG. It was hypothesized that synthetic peptides of this region should induce EAG. Human and rat peptides of this region were synthesized and rats were immunized to define the nephritogenic epitope. A 13-AA rat peptide induced EAG with proteinuria, decreased renal function, and glomerular basement membrane (GBM)-bound deposits in half of the rats. This peptide induces lymph node cell proliferation and development of antibodies to epitopes of alpha3(IV)NC1 external to the peptide immunogen. Carboxy-terminal extension to 21 amino acids results in all rats' demonstrating anti-GBM antibody and severe EAG. Asparagine at position 19 is critical for EAG induction. None of the 50 rats that were immunized with peptide that contained human sequence with isoleucine at position 19 developed EAG, whereas rat sequence with asparagine 19 induced EAG. Truncation of amino terminal AA of the peptide aborts EAG induction. These studies demonstrate that a T cell epitope of alpha3(IV)NC1 induces lymph node cell proliferation, EAG, and intramolecular epitope spreading; that the length of this peptide influences the formation of anti-GBM antibody; and that the presence of asparagine at position 19 of the peptide is critical to disease induction.
已鉴定出IV型胶原非胶原结构域α3链的氨基末端区域[α3(IV)NC1]，该区域可在大鼠中诱导实验性自身免疫性肾小球肾炎（EAG）。只有包含与T细胞表位一致的α3(IV)NC1的9个氨基酸跨度的重组抗原才能诱导EAG。据推测，该区域的合成肽应能诱导EAG。合成了该区域的人源和大鼠源肽，并对大鼠进行免疫以确定致肾炎表位。一种13个氨基酸的大鼠肽在一半的大鼠中诱导出了伴有蛋白尿、肾功能下降和肾小球基底膜（GBM）结合沉积物的EAG。该肽可诱导淋巴结细胞增殖以及针对肽免疫原外部的α3(IV)NC1表位的抗体产生。将羧基末端延伸至21个氨基酸会导致所有大鼠都出现抗GBM抗体和严重的EAG。第19位的天冬酰胺对于EAG诱导至关重要。用第19位为异亮氨酸的人源序列肽免疫的50只大鼠中没有一只发生EAG，而第19位为天冬酰胺的大鼠序列则可诱导EAG。该肽氨基末端氨基酸的截断会中止EAG诱导。这些研究表明，α3(IV)NC1的一个T细胞表位可诱导淋巴结细胞增殖、EAG和分子内表位扩展；该肽的长度会影响抗GBM抗体的形成；并且该肽第19位天冬酰胺的存在对于疾病诱导至关重要。
