Transcriptome analysis of peripheral blood of Schistosoma mansoni infected children from the Albert Nile region in Uganda reveals genes implicated in fibrosis pathology

Abstract

Over 290 million people are infected by schistosomes worldwide. Schistosomiasis control efforts focus on mass drug treatment with praziquantel (PZQ), a drug that kills the adult worm of all Schistosoma species. Nonetheless, re-infections have continued to be detected in endemic areas with individuals living in the same area presenting with varying infection intensities. Our objective was to characterize the transcriptome profiles in peripheral blood of children between 10-15 years with varying intensities of Schistosoma mansoni infection living along the Albert Nile in Uganda. RNA extracted from peripheral blood collected from 44 S. mansoni infected (34 high and 10 low by circulating anodic antigen [CAA] level) and 20 uninfected children was sequenced using Illumina NovaSeq S4 and the reads aligned to the GRCh38 human genome. Differential gene expression analysis was done using DESeq2. Principal component analysis revealed clustering of gene expression by gender when S. mansoni infected children were compared with uninfected children. In addition, we identified 14 DEGs between S. mansoni infected and uninfected individuals, 56 DEGs between children with high infection intensity and uninfected individuals, 33 DEGs between those with high infection intensity and low infection intensity and no DEGs between those with low infection and uninfected individuals. We also observed upregulation and downregulation of some DEGs that are associated with fibrosis and its regulation. These data suggest expression of fibrosis associated genes as well as genes that regulate fibrosis in S. mansoni infection. The relatively few significant DEGS observed in children with schistosomiasis suggests that chronic S. mansoni infection is a stealth infection that does not stimulate a strong immune response.

Fig 1. Screening and recruitment of children for differential gene expression.

Of 727 children recruited for the schistosomiasis study project following consent and assent, 152 were recruited for gene expression studies. Seventy-one (71) were excluded for not having the required amount of RNA required for sequencing hence 81 samples from recruited children were sequenced. One (1) sample did not pass the QC; therefore 80 samples were sequenced; 64 samples were analysed for differentially expressed genes following removal of 5 outliers and 11 samples without CAA results.

Fig 2. PCA showed clustering of differentially expressed genes by gender when S. mansoni infected children were compared to uninfected.

Fig 3. Volcano plots showing differentially expressed genes between S. mansoni infected and uninfected individuals.

A Fourteen (14) significant DEGs (9 upregulated and 5 down regulated) were identified among the S. mansoni infected children compared with the uninfected. B Fifty-six (56) significant DEGs (43 upregulated and 13 downregulated) were identified among children with high S. mansoni infection intensity compared to the uninfected. C Thirty-three (33) significant DEGs (30 upregulated and 3 downregulated) were identified among children with high S. mansoni infection intensity compared to those with low infection intensity. D No significant DEGs were identified among children with low S. mansoni infection intensity compared to the uninfected.

Fig 4. Counts of DEGs among the different infection intensity comparisons.

Fig 5

A Differential expression of genes with stunting. One gene (NCEH1) was significantly upregulated in stunting. B Differential expression of genes with BMI. Two genes (MUC5B and DMD were upregulated whereas one gene (SERPINA10) was downregulated by increased BMI.