Misaki Taro, Naka Shuhei, Kuroda Keiko, Nomura Ryota, Shiooka Tempei, Naito Yoshitaka, Suzuki Yumiko, Yasuda Hideo, Isozaki Taisuke, Nakano Kazuhiko
Division of Nephrology, Seirei Hamamatsu General Hospital, 2-12-12 Sumiyoshi, Naka-ku, Hamamatsu, Shizuoka, 430-8558, Japan.
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan.
Clin Exp Nephrol. 2015 Oct;19(5):844-50. doi: 10.1007/s10157-014-1072-0. Epub 2014 Dec 10.
IgA nephropathy (IgAN) is the most common primary chronic glomerulonephritis; however, its precise initiating pathogenesis remains unclear. Streptococcus mutans is a major pathogen of human dental caries. S. mutans strains with the cnm gene encoding Cnm, a collagen-binding protein, have been reported to contribute to the development of systemic diseases. However, the contribution of S. mutans with Cnm in the development of IgAN has not been reported. The aim of this study was to investigate the prevalence of cnm-positive S. mutans in IgAN patients and clarify the effects of cnm-positive S. mutans on the histological pathology of IgAN.
We identified the cnm gene in S. mutans isolated in saliva specimens, which were collected from IgAN patients (n = 53) and control subjects (n = 50). We evaluated the collagen-binding properties of S. mutans in IgAN patients and controls. The clinical parameters and histological scores were also assessed in IgAN patients.
The rates of S. mutans isolation in IgAN and control groups were 84.0 and 84.9 %, respectively, not significantly dfferent. cnm-positive strains were significantly more prevalent in the IgAN group than in controls (32.1 vs. 14.0 %, p < 0.05). With regard to collagen-binding assays, the binding rates of cnm-positive strains were significantly higher in the IgAN group than in controls (96.6 vs. 30.0, p < 0.05). In addition, the segmental glomerulosclerosis scores were significantly higher in cnm-positive patients with IgAN than in cnm-negative patients with IgAN (0.94 vs. 0.57, p < 0.05).
cnm-positive S. mutans strains are potentially associated with the pathogenesis of IgAN.
IgA肾病（IgAN）是最常见的原发性慢性肾小球肾炎；然而，其确切的起始发病机制仍不清楚。变形链球菌是人类龋齿的主要病原体。据报道，携带编码胶原结合蛋白Cnm的cnm基因的变形链球菌菌株与全身性疾病的发生有关。然而，具有Cnm的变形链球菌在IgA肾病发生中的作用尚未见报道。本研究的目的是调查IgA肾病患者中cnm阳性变形链球菌的患病率，并阐明cnm阳性变形链球菌对IgA肾病组织病理学的影响。
我们在从IgA肾病患者（n = 53）和对照受试者（n = 50）收集的唾液标本中分离出的变形链球菌中鉴定cnm基因。我们评估了IgA肾病患者和对照中变形链球菌的胶原结合特性。还对IgA肾病患者的临床参数和组织学评分进行了评估。
IgA肾病组和对照组的变形链球菌分离率分别为84.0%和84.9%，无显著差异。cnm阳性菌株在IgA肾病组中的患病率显著高于对照组（32.1%对14.0%，p < 0.05）。关于胶原结合试验，IgA肾病组中cnm阳性菌株的结合率显著高于对照组（96.6对30.0，p < 0.05）。此外，cnm阳性的IgA肾病患者的节段性肾小球硬化评分显著高于cnm阴性的IgA肾病患者（0.94对0.57，p < 0.05）。
cnm阳性的变形链球菌菌株可能与IgA肾病的发病机制有关。
