Introduction

Studies of target organs at the time of acute graft versus host disease (GVHD) are needed to identify novel inflammatory and regulatory pathways.

Methods

We performed a prospective transcriptome analysis of gastrointestinal (GI) biopsies at diagnosis of acute GI GVHD and compared these to bone marrow transplant (BMT) patients without GVHD. Allogeneic BMT patients ≥2 years old undergoing endoscopy for clinical indications had 2 additional rectosigmoid mucosal biopsies for transcriptome analysis.

Transcriptome data from 211 ulcerative colitis (UC) patients were included to uncover genes and pathways shared between GVHD and UC. Rectal biopsies from 20 children without inflammatory bowel disease (IBD) served as controls.

Results

Twenty-one patients underwent endoscopy pre (n=5) or post BMT (n=16). Median age of patients was 13.5 years (range 4.5 -25 years). Four patients were excluded from analyses (pre BMT colitis n=3, no lower GI biopsy n=1).

Nine patients had acute GI GVHD, while 8 patients did not (Table 1). Principal component analysis shows patient clustering of those with and without GVHD, suggesting distinct transcriptomic mechanisms driving disease (Figure 1A). We identified 1310 significant genes, 144 of which were downregulated and 1266 upregulated in acute GVHD compared to no GVHD (Figure 1B). Top upregulated biological processes in GVHD revealed an innate antimicrobial response and associated cytokine signaling, notable for interferons. Top 20 differentially expressed genes in acute GVHD (Table 2), include CXCL9, CXCL10 and CXCL11, which are chemokines involved in GVHD, and IDO1 which regulates tryptophan metabolism.

Four hundred and ninety shared genes were upregulated, and 126 genes were downregulated in GVHD and UC. Notable shared downregulated pathways involved butyrate metabolism (Table 3). DUOXA2, a gene involved in regulating innate antimicrobial responses in IBD, was the top upregulated genes in pediatric IBD and was the second highest differentially expressed gene in the acute GVHD, providing additional rationale for intestinal microbiome modulation in both diseases.

Genes involving the ERK1/2 cascade (Table 4) were upregulated in acute GVHD (p=1.67 × 10 ⁻³) providing rationale for exploring ERK1/2 inhibition as novel acute GVHD treatment.

Conclusions

Acute GI GVHD has a distinct transcriptome signature which includes pathways of innate antimicrobial responses highlighting the role for microbiome modulation. The ERK1/2 cascade pathway is upregulated, suggesting a novel target in acute GI GVHD. Acute GI GVHD has important similarities with the UC transcriptome, including upregulation of DUOXA2 and downregulation in butyrate metabolism in both.

中文翻译：

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小儿急性Gvhd：胃肠道活组织检查的转录组分析揭示了小儿急性GI Gvhd的独特特征，涉及ERK途径以及与小儿炎症性肠病的相似性

介绍

需要研究急性移植物抗宿主病（GVHD）时的靶器官，以鉴定新的炎症和调节途径。

方法

我们在诊断急性胃肠道GVHD时进行了胃肠道（GI）活检的前瞻性转录组分析，并将其与无GVHD的骨髓移植（BMT）患者进行了比较。≥2岁的同种异体BMT患者接受内镜检查以适应临床指征，并另外进行了2次乙状结肠乙状结肠黏膜活检以进行转录组分析。

包括来自211名溃疡性结肠炎（UC）患者的转录组数据，以揭示GVHD和UC之间共有的基因和途径。来自20名无炎性肠病（IBD）的儿童的直肠活检作为对照。

结果

21名患者在BMT之前（n = 5）或术后（n = 16）接受了内镜检查。患者的中位年龄为13.5岁（范围4.5 -25岁）。四名患者被排除在分析之外（BMT前结肠炎n = 3，没有更低的胃肠道活检n = 1）。

9名患者有急性GI GVHD，而8名患者没有（表1）。主成分分析显示有和没有GVHD的患者聚集，提示驱动疾病的独特转录组机制（图1A）。与没有GVHD相比，我们在急性GVHD中鉴定了1310个重要基因，其中有144个基因被下调，而1266个基因被上调（图1B）。GVHD的最高上调生物学过程揭示了先天的抗菌反应和相关的细胞因子信号传导，尤其是干扰素。急性GVHD的前20个差异表达基因（表2）包括参与GVHD的趋化因子CXCL9，CXCL10和CXCL11，以及调节色氨酸代谢的IDO1。

GVHD和UC中共有490个共享基因被上调，而126个基因被下调。共有的共同下调的途径涉及丁酸代谢（表3）。DUOXA2是参与调节IBD中先天性抗微生物反应的基因，是小儿IBD中表达最高的基因，并且是急性GVHD中第二高表达差异的基因，为这两种疾病中肠道微生物组的调控提供了更多依据。

涉及ERK1 / 2级联的基因（表4）在急性GVHD中被上调（p = 1.67×10 ^-3），为探索ERK1 / 2抑制作为新的急性GVHD治疗提供了理论依据。

结论

急性GI GVHD具有独特的转录组特征，其中包括固有的抗微生物反应途径，突出了微生物组调节的作用。ERK1 / 2级联途径上调，表明急性胃肠道GVHD的新目标。急性GI GVHD与UC转录组具有重要的相似之处，包括DUOXA2的上调和两者的丁酸代谢的下调。