Comparison and Analysis of Gut Microbiota in Children With IgA Vasculitis With Different Clinical Symptoms

Abstract

Background: Henoch-Schönlein purpura, now called immunoglobulin A (IgA) vasculitis, is a common autoimmune disease in children, its association with gut microbiota composition remains unknown. Methods: The collected cases were divided into three groups: G1 group of simple skin type, G2 group with no digestive tract expression, G3 group of mixed digestive tract, and C group of healthy children. The fecal samples of each group of children were collected and the sequencing data was processed and analyzed. The dilution curve reflected the reasonableness of the amount of sequencing data. Results: The number of species composition sequences in the G1, G2 and G3 groups was lower than that in the C group, especially for the G2 and G3 groups. The four most abundant bacteria were Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria. The relative abundance of Proteobacteria in the G2 and G3 groups was significantly higher than that in the G1 and C groups, while the relative abundance of Actinobacteria was significantly reduced, and the relative abundance of Actinobacteria in the G1 group was lower than that in the C group. Principal component analysis of the UPGMA clustering tree and each group of samples showed that the microbial community composition of the same group of samples was similar. Conclusions: The abundance of intestinal microbes in children with IgA vasculitis is lower than in normal children. Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria are the four most abundant bacteria in the intestinal flora of children. Proteobacteria and Actinobacteria are associated with organ involvement in IgA vasculitis.

Keywords: IgA vasculitis; children; gut microbiota; immune disease; sequencing.

Figure 1

Number of gene sequences in each sample. The abscissa is the sample name; the ordinate indicates the number of sequences that are annotated to that level; the top-down color order of the histogram corresponds to the legend's color order on the right.

Figure 2

Relative abundance of the intestinal flora at the family level in children. The abscissa is the sample name; the ordinate indicates the relative abundance; “Others” represents the sum of the relative abundance of all the orders of the 10 largest phyla with the highest relative abundance (The maximum relative abundance of a phylum in all samples).

Figure 3

Relative abundance of the intestinal flora at the family level in the four groups of children (Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes). The abscissa is the group name; the ordinate indicates the percentage of abundance of a particular intestinal flora; the column color corresponds to the legend color on the right. (A) Relative abundance (%) of Firmicutes in the intestinal flora of the four groups of children. (B) Relative abundance (%) of Actinobacteria in the intestinal flora of the four groups of children. (C) Relative abundance (%) of Proteobacteria, in the intestinal flora of the four groups of children. (D) Relative abundance (%) of Bacteroidetes, in the intestinal flora of the four groups of children.

Figure 4

Cluster of relative abundance of the intestinal flora at the phylum level in each sample. The left side is the UPGMA cluster tree structure, on the right is the sample at the phylum level of the relative abundance of specie distribution map.

Figure 5

Principal component analysis of different samples at the phylum level. The abscissa and the ordinate represent two principal components, respectively, and the percentage indicates the contribution of the principal component to the sample difference; the same group of samples is represented by the same color dot.

Figure 6

Representative rarefaction curves. The abscissa is the number of valid sequences per sample, the ordinate is the number of operational taxonomic units (OTUs) species observed. Each curve represents a different sample.