Activation of the IDO1-GCN2-ATF4-CHOP Pathway During the Massive Generation of Antibody-Secreting Cells in Dengue Patients Through Single-Cell Transcriptomics

Abstract

Dengue, a widespread mosquito-borne disease, annually afflicts millions globally, posing substantial mortality risks. Preceding disease defervescence, a marked and transient surge in antibody-secreting cell (ASC) frequency correlates with disease severity, paralleled by heightened tryptophan degradation. Investigating details of this process through single-cell transcriptomics from public repositories, our data pinpoint CD14+ monocytes as principal IDO1 and IDO2 expressors, implicating them, rather than B cells, in initiating tryptophan metabolism. Interestingly, naive B cells exhibit altered gene expression indicative of early impact by tryptophan deficiency before defervescence with a potential impact on the B cell fate. Dengue-induced ASCs upregulated GCN2, PERK, eIF2a, ATF4 genes as well as BIM and CASP-3. However, the high expression of anti-apoptotic genes (FKBP8 [a CHOP-regulated gene], BCL-XL, BCL-2, MCL-1) allows enhanced ASC survival. Proliferation and differentiation-related genes (eIF4EBP1, RRM2, and HIF1a) were also upregulated in ASCs. These findings untangle how Dengue modulates the host metabolism and B-cell responses, although further research is needed to fully understand their implications on disease progression.

Keywords: B cells; blood; kynurenine; tryptophan metabolism; viral infection.

Figure 1.

Monocytes are the main subset of peripheral blood mononuclear cells from Dengue patients that can initiate tryptophan degradation. (A) Validated single cells derived from different time points of the Dengue symptomatologic phase were clustered in a Total PBMC UMAP (B). (C) Expression of tryptophan-degrading enzymes (IDO1, IDO2, and TPH2) were evaluated in all clusterized cells from the Total PBMC UMAP.

Figure 2.

Extensive generation of antibody-secreting cells from Dengue patients occurs simultaneously with the alteration in the expression profile of genes associated with the tryptophan metabolism in naive B cells. (A) Kinetics of distinct B cell subsets before and after Dengue defervescence (day 0). Absolute number (B) and percentage (C) of B cell subsets at different time points during disease symptomatology. (D) Cellular location where genes associated with the tryptophan metabolism are usually activated. Genes written in bold font had their kinetics of expression (E) evaluated in the transcriptome of single-B cells. Source: Created in BioRender. Gonzalez, P. (2025) https://BioRender.com/qrr3ejc.

Figure 3.

Activation of IDO-GCN2-ATF4 pathway is triggered during the period of B cell differentiation into antibody-secreting cells found in Dengue patients. (A) Potential B cell activation via contact with DCs in an environment with low concentration of tryptophan. Genes written in bold font had their expression evaluated in the transcriptome of single-B cells. (B) B cell UMAP presents distinct cell subsets after their isolation from PBMCs. (C) Kinetics of gene expression related to IDO-GCN2-ATF4 pathway before and after Dengue defervescence (day 0). Source: Created in BioRender. Gonzalez, P. (2025) https://BioRender.com/uy350cq.

Figure 4.

Modification of gene expression profiles related to the axis IDO-GCN2-ATF4 in several B cell subsets during the onset of Dengue. Gene expression related to this pathway had its kinetics evaluated in the following B-cell subsets: (A) Naive, (B) Intermediate, (C) Memory, (D) Plasmablast, and (E) Plasma cell.