Tandon Mayank, Perez Paola, Burbelo Peter D, Calkins Catherine, Alevizos Ilias
Sjögren's Syndrome and Salivary Gland Dysfunction Unit, NIH, National Institute of Dental and Craniofacial Research, Bethesda, MD; Dept.of Microbiology & Immunology, Jefferson College of Biomedical Sciences, T.Jefferson University, Philadelphia, PA, USA.
Sjögren's Syndrome and Salivary Gland Dysfunction Unit, National Institutes of Health, National Institute of Dental and Craniofacial Research, Bethesda, MD, USA.
Clin Exp Rheumatol. 2017 Sep-Oct;35(5):777-785. Epub 2017 Apr 18.
Little is known about the molecular details regarding the contribution of different cell types of the salivary gland to the altered gene expression profile seen in Sjögren's syndrome (SS).
Using laser microdissection, tissue samples enriched in acini, ducts and inflammatory foci in subjects with and without SS were isolated for RNA-seq analysis. Gene expression profiles were analysed and selected enriched genes were further examined using real time PCR and by immunofluorescence.
RNA-seq analysis of salivary biopsies from subjects with and without SS revealed marked differences in gene expression occurring in the ductal and infiltrating cells compared to acinar cells. Up-regulated genes in the SS ductal cells included C4A complement and the SLC26A9 ion channel. The inflammatory infiltrate showed the most dramatic differences in gene expression and contained up-regulated genes associated with T-cells, natural killer, dendritic and basophils/mast cells. qPCR with total salivary gland mRNA confirmed the differential mRNA expression of several genes (MMP9, FOL1HB, CCL21, CCR7), thereby validating the approach. Additional immunofluorescence studies demonstrated high expression and co-localisation of CCL21 chemokine and CCR7 chemokine receptor within the SS infiltrates.
Major gene expression changes in the salivary gland of SS were detected in the ductal and inflammatory cells and not in the acinar cells. Two chemokines involved in immune cell trafficking to secondary lymphoid tissue, CCR7 and CCL21, showed markedly increased expression and may contribute to the recruitment of diverse immune cells to the salivary glands, causing inflammation and loss of secretory function.
关于唾液腺不同细胞类型对干燥综合征（SS）中基因表达谱改变的贡献，目前对其分子细节了解甚少。
使用激光显微切割技术，从患有和未患有SS的受试者中分离出富含腺泡、导管和炎症灶的组织样本，用于RNA测序分析。分析基因表达谱，并使用实时PCR和免疫荧光进一步检测选定的富集基因。
对患有和未患有SS的受试者的唾液活检组织进行RNA测序分析发现，与腺泡细胞相比，导管和浸润细胞中的基因表达存在显著差异。SS导管细胞中上调的基因包括C4A补体和SLC26A9离子通道。炎症浸润在基因表达上显示出最显著的差异，并且包含与T细胞、自然杀伤细胞、树突状细胞和嗜碱性粒细胞/肥大细胞相关的上调基因。用唾液腺总mRNA进行的qPCR证实了几个基因（MMP9、FOL1HB、CCL21、CCR7）的mRNA表达差异，从而验证了该方法。额外的免疫荧光研究表明，CCL21趋化因子和CCR7趋化因子受体在SS浸润灶中高表达且共定位。
在SS患者的唾液腺中，主要的基因表达变化在导管和炎症细胞中被检测到，而不是在腺泡细胞中。参与免疫细胞向次级淋巴组织迁移的两种趋化因子CCR7和CCL21，其表达明显增加，可能有助于多种免疫细胞向唾液腺募集，从而导致炎症和分泌功能丧失。
