Pathology Center, Iwaki City Medical Center, Iwaki, Japan.
Department of Dentistry and Oral Surgery, Iwaki City Medical Center, Iwaki, Japan.
J Clin Exp Hematop. 2021 Jun 5;61(2):85-92. doi: 10.3960/jslrt.20060. Epub 2021 May 14.
Necrotizing lymphadenitis (NEL) is a self-limited systemic disease exhibiting characteristic clinical features. The pathogenesis of the disease remains unclear, but it may be associated with viral infection. In lymph nodes affected by this disease, innumerable plasmacytoid dendritic cells produce interferon-α when triggered by certain viral stimuli. IFN-α presents antigens causing the transformation of CD8 cells into immunoblasts and apoptosis of CD4 cells. From the perspective of innate immunity, UNC93B1, an endoplasmic reticulum (ER)-resident protein, associates more strongly with TLR9 than TLR7. Homeostasis is maintained under normal conditions. However, in NEL, TLR 7 was observed more than TLR 9, possibly because mutant type UNC93B1 associates more tightly with TLR7. The inhibitory effects against TLR7 by TLR9 were reported to disappear. It is likely that more TLR7 than TLR9 is transported from the ER to endolysosomes. In conclusion, overexpression of TLR7, an innate immune sensor of microbial single-stranded RNA, is inferred. Consequently, NEL may be induced.
坏死性淋巴结炎（NEL）是一种自限性全身性疾病，具有特征性的临床特征。该疾病的发病机制尚不清楚，但可能与病毒感染有关。在受这种疾病影响的淋巴结中，无数浆细胞样树突状细胞在受到某些病毒刺激时产生干扰素-α。IFN-α 呈现抗原，导致 CD8 细胞转化为免疫母细胞和 CD4 细胞凋亡。从先天免疫的角度来看，内质网（ER）驻留蛋白 UNC93B1 与 TLR9 的结合比 TLR7 更强。在正常情况下保持内稳态。然而，在 NEL 中，观察到 TLR7 多于 TLR9，这可能是因为突变型 UNC93B1 与 TLR7 结合更紧密。据报道，TLR9 对 TLR7 的抑制作用消失。可能是从 ER 转运到内溶酶体的 TLR7 多于 TLR9。总之，推断出微生物单链 RNA 的先天免疫传感器 TLR7 的过度表达。因此，可能会引发 NEL。
