Plasma exosomal IRAK1 can be a potential biomarker for predicting the treatment response to renin-angiotensin system inhibitors in patients with IgA nephropathy

Abstract

Background: Renin-angiotensin system inhibitors (RASi) are the first choice and basic therapy for the treatment of IgA nephropathy (IgAN) with proteinuria. However, approximately 40% of patients have no response to RASi treatment. The aim of this study was to screen potential biomarkers for predicting the treatment response of RASi in patients with IgAN.

Methods: We included IgAN patients who were treatment-naive. They received supportive treatment, including a maximum tolerant dose of RASi for 3 months. According to the degree of decrease in proteinuria after 3 months of follow-up, these patients were divided into a sensitive group and a resistant group. The plasma of the two groups of patients was collected, and the exosomes were extracted for high-throughput sequencing. The screening of hub genes was performed using a weighted gene co-expression network (WGCNA) and filtering differentially expressed genes (DEGs). We randomly selected 20 patients in the sensitive group and 20 patients in the resistant group for hub gene validation by real-time quantitative polymerase chain reaction (qRT-PCR). A receiver operating characteristic (ROC) curve was used to evaluate hub genes that predicted the efficacy of the RASi response among the 40 validation patients.

Results: After screening 370 IgAN patients according to the inclusion and exclusion criteria and the RASi treatment response evaluation, there were 38 patients in the sensitive group and 32 patients in the resistant group. IRAK1, ABCD1 and PLXNB3 were identified as hub genes by analyzing the high-throughput sequencing of the plasma exosomes of the two groups through WGCNA and DEGs screening. The sequencing data were consistent with the validation data showing that these three hub genes were upregulated in the resistant group compared with the sensitive group. The ROC curve indicated that IRAK1 was a good biomarker to predict the therapeutic response of RASi in patients with IgAN.

Conclusions: Plasma exosomal IRAK1 can be a potential biomarker for predicting the treatment response of RASi in patients with IgAN.

Keywords: Biomarker; Exosome; IgA nephropathy; Renin-angiotensin system inhibitors; Treatment response.

Figure 1

Details of patients screened, recruited and included in the final analysis. RASi, renin-angiotensin system inhibitors; eGFR, estimated glomerular filtration rate.

Figure 2

Quality examination of plasma exosomes. (A) The average particle size of exosomes was measured by dynamic light scattering (DLS). (B) The form of plasma exosomes was observed by transmission electron microscopy (TEM). Scale bar = 100 nm. (C) The purity of plasma exosomes was evaluated through the flow cytometry calculating the positive rates of CD81 and CD63.

Figure 3

Hub gene screening by DEGs screening and WGCAN. (A, B) Volcano plot and heatmap of DEGs between the sensitive group (n=5) and the resistant group (n=5). (C) Gene dendrogram. (D) Heatmaps visualizing 400 randomly selected genes in the network to depict the topological overlap matrix. (E) Heatmap of module–trait relationships. (F) The distribution of GS and MM was presented as a scatter diagram in the tan module.

Figure 4

Hub gene identification and validation. (A) The final hub genes were determined by Venn diagram. (B) Expression of IRAK1, ABCD1 and PLXNB3 mRNA in the plasma exosomes in the sensitive group (n=20) and resistance group (n=20). Mean ± SEM, *P < 0.05, **P < 0.01, ***P < 0.001. The ROC curve of IRAK1 (C), ABCD1 (D) and PLXNB3 (E) in predicting the RASi response in IgAN.