3.1 Download and analysis of data.
We searched the GEO database for samples that meet the research requirements and found that GSE45001 meets our needs. It contains 10 ICC samples and 10 normal samples (Table1).
Table 1. Data from GSE45001; 20 samples from 10 paired CCA patients
GSM1095633
|
Normal Stroma of CCA
|
GSM1095634
|
Tumoral Stroma of CCA
|
GSM1095635
|
Normal Stroma of CCA
|
GSM1095636
|
Tumoral Stroma of CCA
|
GSM1095637
|
Normal Stroma of CCA
|
GSM1095638
|
Tumoral Stroma of CCA
|
GSM1095639
|
Normal Stroma of CCA
|
GSM1095640
|
Tumoral Stroma of CCA
|
GSM1095641
|
Normal Stroma of CCA
|
GSM1095642
|
Tumoral Stroma of CCA
|
GSM1095643
|
Normal Stroma of CCA
|
GSM1095644
|
Tumoral Stroma of CCA
|
GSM1095645
|
Normal Stroma of CCA
|
GSM1095646
|
Tumoral Stroma of CCA
|
GSM1095647
|
Normal Stroma of CCA
|
GSM1095648
|
Tumoral Stroma of CCA
|
GSM1095649
|
Normal Stroma of CCA
|
GSM1095650
|
Tumoral Stroma of CCA
|
GSM1095651
|
Normal Stroma of CCA
|
GSM1095652
|
Tumoral Stroma of CCA
|
3.2 Analysis of the content of immune cells in the sample.
After quality inspection, we found that 7 pairs of samples were available, we downloaded them and included them in the study. The 7 normal samples and 7 ICC samples obtained by the correction were put into the CIBERSORT database to calculate the immune cell content, and the obtained results were plotted as a histogram. Then, we further draw the results into a principal component diagram, from which we can find that the tumor tissue group and the normal tissue group have significantly different immune cell content (Figure 1). Finally, we draw a heat map and visually analyze the expression of immune cells in the sample (Figure 2). The results show that the expression of some immune cells shows differences between tumor tissues and normal tissues.
3.3 Co-expression analysis between immune cells.
Co-expression analysis of the expression levels of immune cells obtained in this study showed that the correlation between T cells regulatory (Tregs) [10-13]and Neutrophils [14-17] was the strongest, with a coefficient of 0.78, and the two cells with the weakest correlation were Macrophages [18-19] and T cells follicular helper [20-21], the correlation coefficient is -0.59 (Figure 3).
3.4 Immune cells with significantly different expressions in ICC and normal tissues are screened.
By drawing a violin chart (Figure 4), We found that the expression levels of Dendritic cells activated (Figure5A), Macrophages M2 (Figure5B) and T cells regulatory (Tregs) (Figure5C) in ICC were higher than normal tissues and the expression levels of Monocytes (Figure5D), T cells follicular helper (Figure5E) and Macrophages M1 (Figure5F) in ICC were lower than normal tissues
3.5 Principal Component Analysis (PCA)
After obtaining the matrix of immune cells, we wondered whether these immune cells could distinguish between the normal group and the tumor group. Then we did principal component analysis. The dimensionality was reduced to PCA1 and PCA2 by PCA, and the X-axis was labeled as PCA1 and Y-axis as PCA2. Then an ellipse was simulated for the normal group and the tumor group, respectively. If the two ellipses did not cross, it suggested that the 22 immune cells could distinguish the normal group from the tumor group well. We used the "GGplot2" package for analysis, and the results showed that the two ellipses did not cross (Figure 6), indicating that the 22 kinds of immune cells in this study could well distinguish the tumor group from the normal group.
3.6 Immune cells related to ICC survival prognosis.
We further explore the relationship between each immune cell in Figure 5 and ICC survival in the Timer2.0 database. It was found that the survival rate of the group with high Monocyte cell content was significantly better than that of the group with low Monocyte cell content.
The survival rate of the group with high T cell regulatory content was better than that of the group with low regulatory content. However, the data of other cells is not sufficient at present, and further research and supplement are needed.