Immunophenotyping and Transcriptional Profiling of Human Plasmablasts in Dengue

Abstract

Plasmablasts represent a specialized class of antibody secreting effector B cell population that transiently appear in blood circulation following infection or vaccination. The expansion of these cells generally tends to be massive in patients with systemic infections leading to viral hemorrhagic fevers such as dengue or ebola. To gain a detailed understanding of the human plasmablast responses beyond antibody expression, here we performed immunophenotyping and RNA seq analysis of the plasmablasts from dengue febrile children in India. We found that the plasmablasts expressed several adhesion molecules and chemokines or chemokine receptors that are involved in endothelial interactions or homing to inflamed tissues including skin, mucosa, and intestine; and upregulated expression of several cytokine genes that are involved in leukocyte extravasation and angiogenesis. These plasmablasts also upregulated expression of receptors for several B cell pro-survival cytokines that are known to be induced robustly in systemic viral infections such as dengue, some of which generally tend to be relatively higher in patients manifesting hemorrhage and/or shock compared to patients with mild febrile infection. These findings improve our understanding of human plasmablast responses during the acute febrile phase of systemic dengue infection. Importance Dengue is globally spreading, with over 100 million clinical cases annually, with symptoms ranging from mild self-limiting febrile illness to more severe and sometimes life-threatening dengue hemorrhagic fever or shock, especially among children. The pathophysiology of dengue is complex and remains poorly understood despite many advances indicating a key role for antibody dependent enhancement of infection. While serum antibodies have been extensively studied, the characteristics of the early cellular factories responsible for antibody production, i.e., plasmablasts, are only beginning to emerge. This study provides a comprehensive understanding of the transcriptional profiles of human plasmablasts from dengue patients.

Single-cell RNA sequencing reveals the expansion of circulating tissue-homing B cell subsets in secondary acute dengue viral infection

“…Our study, along with others, has provided evidence documenting the potential migratory functions of B cell subsets to tissues during acute DENV infection [ [14] , [15] , [16] ]. A previous report has demonstrated that PCs and PBs showed the up-regulation of inflamed tissue-homing molecules, CXCR3 and CCR2, on ASCs, but not CCR10, a chemokine receptor suggested for its role in skin-homing [ 15 ].…”

“…Moreover, during the acute phase of secondary DENV infection, there is typically a massive expansion of plasma cells (PCs) and plasmablasts (PBs), differentiated forms of B cells capable of secreting antibodies (also known as antibody secreting cells or ASCs) [ 12 , 13 ]. These peripheral PCs and PBs have been shown to be cross-reactive DENV-specific ASCs that represent only a minor portion of memory B cell pool [ 12 , 14 ]. Nevertheless, their origin, function, and tissue homeostasis remain largely unknown.…”

“…Previously, we and others have reported the possible tissue-homing of B cell subpopulations during acute DENV infection [ [14] , [15] , [16] ], including the upregulation of inflamed tissue-homing molecules, CXCR3 and CCR2 [ 15 ], and the skin-homing molecule Cutaneous lymphocyte-associated antigen (CLA) on PBs [ 14 ]. In our recent study [ 16 ], we utilized single-cell transcriptomics to study the dynamics of immune responses in the peripheral blood of DENV-infected patients over the course of infection.…”

“…To demonstrate the possible homing functions among the major B cell subpopulations, in this study, we investigated the expression of tissue-homing molecules and surface protein expression of the skin-homing molecule, CLA, in a larger sample cohort, comparing between the acute and convalescent phases from the same DENV–infected patients, as well as healthy controls (HCs), which is not the case in previous studies [ [14] , [15] , [16] ]. Specifically, we focused on investigating the cell surface expression of the skin-homing molecule, CLA, on B cell subsets by performing flow cytometry on 16 blood samples collected from DENV-infected patients.…”