Supplementary Material for: The Identification of Gene Expression Profiles Associated with Granulomatous Mastitis

<b><i>Background:</i></b> Granulomatous mastitis (GM) is a rare chronic inflammatory disease of the breast. The current therapeutic effects of the antibiotic therapy and surgical or immunomodulatory (steroid) treatment are normally poor due to the unclear etiology. <b><i>Method:</i></b> This study aimed to identify the differentially expressed mRNAs in GM tissues using RNA sequencing and further explored the functions of differentially expressed mRNAs resulting in GM. Moreover, we revealed the relationship between GM and breast cancer by shared highly expressed genes in GM tissues and breast cancer tissues. <b><i>Results:</i></b> A total of 12,115 mRNAs were analyzed in the whole expression profile, and 207 mRNAs (136 upregulated and 71 downregulated mRNAs) were differently expressed between the GM tissues and normal tissues. The enrichment analysis showed that the differentially expressed mRNAs were enriched in the biological processes and played a significant role in the immune system. Besides, the genes expressed significantly highly in breast cancer tissues are found to be enriched with GM genes, which may explain the similar clinical features between breast cancer and GM. We also found that the HSD11B1 gene which was differentially expressed in GM was used as drug target of prednisone, which is a common treatment for GM. <b><i>Conclusion:</i></b> This study is the first to use sequencing technology to elucidate the genetic mechanisms of GM. The finding of this study may have potential value in GM diagnosis and also provides potential drug targets for GM treatment.

**背景：** 肉芽肿性乳腺炎（Granulomatous mastitis, GM）是一种罕见的乳腺慢性炎症性疾病。由于病因尚未明确，当前抗生素治疗、外科手术或免疫调节（类固醇）疗法的疗效通常不佳。
**方法：** 本研究旨在通过RNA测序（RNA sequencing）技术鉴定GM组织中的差异表达信使RNA（mRNA），并进一步探究与GM发病相关的差异表达mRNA的功能。此外，本研究通过分析GM组织与乳腺癌组织中共有的高表达基因，揭示了GM与乳腺癌之间的关联。
**结果：** 本研究的整体表达谱中共分析了12115条mRNA，其中GM组织与正常组织间存在207条差异表达mRNA（136条上调、71条下调）。富集分析结果显示，差异表达mRNA显著富集于多种生物学过程，并在免疫系统中发挥重要作用。此外，乳腺癌组织中显著高表达的基因与GM相关基因存在富集重叠，这或可解释乳腺癌与GM之间相似的临床表型。本研究同时发现，在GM中差异表达的HSD11B1基因可作为泼尼松（prednisone）的药物靶点，而泼尼松正是GM的常用治疗药物。
**结论：** 本研究首次利用测序技术阐明了GM的遗传发病机制。本研究的发现不仅为GM的临床诊断提供了潜在应用价值，同时也为GM的治疗提供了潜在药物靶点。