基于生物信息学对IgA肾病(IgAN)基因表达谱数据进行基因富集分析和免疫细胞浸润分析，旨在研究IgAN相关免疫机制。

从基因表达集(GEO)数据库获取IgAN肾脏组织的GSE93798整体RNA序列数据，利用limma软件包筛选正常对照与IgAN的差异表达基因；利用ggplot2软件包进行基因本体论(GO)和京都基因与基因组百科全书(KEGG)数据库进行通路富集分析；利用CIBERSORT软件获得免疫细胞浸润矩阵；从GEO数据库获取IgAN肾脏组织的GSE127136单细胞RNA序列数据；利用主成分分析法(PCA)和t分布随机邻接嵌入法(t-SNE)获得亚群细胞、亚群细胞的标记基因，对免疫细胞的标记基因进行GO和KEGG分析。

与正常对照组相比，IgAN肾组织有243个基因表达显著上调，104个基因表达显著下调；GO分析提示IgAN差异表达基因多与免疫生物过程相关，KEGG通路分析提示IgAN差异表达基因多富集于感染、免疫通路；免疫细胞浸润分析显示初始B细胞和中性粒细胞在IgAN肾脏组织中下调，浆细胞和M2巨噬细胞在IgAN肾脏组织中上调；单细胞测序分析结果提示CD8⁺T细胞主要参与代谢相关过程，M2巨噬细胞主要参与免疫及代谢相关过程。

免疫在IgAN的发生发展过程中具有重要作用，CD8⁺T细胞、M2巨噬细胞参与了该病理生理机制，有可能作为IgAN的干预靶点。

To perform a bioinformatics-based analysis of gene enrichment and immune cell infiltration according to the gene expression profile data of IgA nephropathy (IgAN), aiming to study the IgAN-related immune mechanisms.

We obtained the GSE93798 bulk RNA-seq data of IgAN kidney tissues from the Gene Expression Omnibus (GEO) database, and the limma software package was used to screen the differentially expressed genes between normal control and IgAN. The ggplot2 software package was applied for pathway enrichment analysis through the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) methods. The CIBERSORT software was applied to obtain the immune cells infiltration matrix, and the single cell RNA sequence data of IgAN kidney tissues were obtained from the GSE127136 chip of the GEO database. The principal component analysis (PCA) and the t-distributed stochastic neighbour embedding (t-SNE) methods were used to obtain subpopulations of cells and their marker genes, and GO and KEGG analyses were performed for the marker genes of the immune cells.

Compared with the normal control group, the IgAN kidney tissue group showed that the expression of 243 genes was significantly up-regulated, while the expression of 104 genes significantly down-regulated. The GO analysis indicated that the differentially-expressed genes in IgAN were mostly related to immune biological processes, and the KEGG pathway analysis suggested that the differentially-expressed genes in IgAN were mostly enriched in infection and immune pathways. The immune cells infiltration analysis showed that naive B cells and neutrophils were down-regulated while the plasma cells and M2 macrophages were up-regulated in the IgAN kidney tissues. Single-cell sequencing analysis results suggested that CD8⁺ T cells were mainly involved in metabolism-related processes, and M2 macrophages mainly involved in both immune- and metabolism-related processes.

The immune played an important role in the occurrence and development of IgAN. CD8⁺ T cells and M2 macrophages were involved in the pathophysiological mechanism, and may serve as the targets for the intervention of IgAN.