Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
Department of General Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin Medical University, Harbin 150086, China.
J Immunol. 2018 May 1;200(9):3142-3150. doi: 10.4049/jimmunol.1800074. Epub 2018 Mar 28.
The spatial and temporal Ag distribution determines the subsequent T cell and B cell activation at the distinct anatomical locations in the lymph node (LN). It is well known that LN conduits facilitate small Ag distribution in the LN, but the mechanism of how Ags travel along LN conduits remains poorly understood. In C57BL/6J mice, using FITC as a fluorescent tracer to study lymph distribution in the LN, we found that FITC preferentially colocalized with LN capsule-associated (LNC) conduits. Images generated using a transmission electron microscope showed that LNC conduits are composed of solid collagen fibers and are wrapped with fibroblastic cells. Superresolution images revealed that high-intensity FITC is typically colocalized with elastin fibers inside the LNC conduits. Whereas tetramethylrhodamine isothiocyanate appears to enter LNC conduits as effectively as FITC, fluorescently-labeled Alexa-555-conjugated OVA labels significantly fewer LNC conduits. Importantly, injection of Alexa-555-conjugated OVA with LPS substantially increases OVA distribution along elastin fibers in LNC conduits, indicating immune stimulation is required for effective OVA traveling along elastin in LN conduits. Finally, elastin fibers preferentially surround lymphatic vessels in the skin and likely guide fluid flow to the lymphatic vessels. Our studies demonstrate that fluid or small molecules are preferentially colocalized with elastin fibers. Although the exact mechanism of how elastin fibers regulate Ag trafficking remains to be explored, our results suggest that elastin can be a potentially new target to direct Ag distribution in the LN during vaccine design.
Ag 的空间和时间分布决定了随后在淋巴结 (LN) 的不同解剖位置处 T 细胞和 B 细胞的激活。众所周知，LN 管腔有助于 LN 中小 Ag 的分布，但 Ag 如何沿 LN 管腔运输的机制仍知之甚少。在 C57BL/6J 小鼠中，我们使用 FITC 作为荧光示踪剂来研究 LN 中的淋巴分布，发现 FITC 优先与 LN 囊相关 (LNC) 管腔共定位。使用透射电子显微镜生成的图像显示，LNC 管腔由固体胶原纤维组成，并被成纤维细胞包裹。超分辨率图像显示，高强度 FITC 通常与 LNC 管腔内的弹性纤维共定位。虽然四甲基罗丹明异硫氰酸酯似乎像 FITC 一样有效地进入 LNC 管腔，但荧光标记的 Alexa-555 缀合 OVA 标记的 LNC 管腔明显较少。重要的是，用 LPS 注射 Alexa-555 缀合的 OVA 可大大增加 LNC 管腔内弹性纤维上的 OVA 分布，表明免疫刺激是有效沿 LN 管腔中的弹性蛋白运输 OVA 所必需的。最后，弹性纤维优先围绕皮肤中的淋巴管，并且可能引导流体流向淋巴管。我们的研究表明，流体或小分子优先与弹性纤维共定位。尽管弹性纤维如何调节 Ag 运输的确切机制仍有待探索，但我们的结果表明，弹性蛋白可以成为疫苗设计中在 LN 中定向 Ag 分布的潜在新靶标。
