Comparative phenotypical analysis of B cells in fresh and cryopreserved mononuclear cells from blood and tissue of rhesus macaques

B cells and atherosclerosis: A HIV perspective

Atherosclerosis remains a leading cause of cardiovascular disease (CVD) globally, with the complex interplay of inflammation and lipid metabolism at its core. Recent evidence suggests a role of B cells in the pathogenesis of atherosclerosis; however, this relationship remains poorly understood, particularly in the context of HIV. We review the multifaceted functions of B cells in atherosclerosis, with a specific focus on HIV. Unique to atherosclerosis is the pivotal role of natural antibodies, particularly those targeting oxidized epitopes abundant in modified lipoproteins and cellular debris. B cells can exert control over cellular immune responses within atherosclerotic arteries through antigen presentation, chemokine production, cytokine production, and cell-cell interactions, actively participating in local and systemic immune responses. We explore how HIV, characterized by chronic immune activation and dysregulation, influences B cells in the context of atherosclerosis, potentially exacerbating CVD risk in persons with HIV. By examining the proatherogenic and antiatherogenic properties of B cells, we aim to deepen our understanding of how B cells influence atherosclerotic plaque development, especially within the framework of HIV. This research provides a foundation for novel B cell-targeted interventions, with the potential to mitigate inflammation-driven cardiovascular events, offering new perspectives on CVD risk management in PLWH.

Detection of rotavirus- and norovirus-specific IgG memory B cells in tonsils

Because rotavirus (RV) and norovirus (NoV) are transmitted through the fecal-oral route, tonsils due to their location within the oropharynx may sample or become infected with these viruses. We investigated if RV and NoV RNA/antigen, or virus-specific memory/plasma B cells can be detected in the tonsils. While neither RV/NoV antigen, nor genomic RNA was detected, 90% (27/30) of tonsils tested had RV- and NoV-specific IgG memory B cells. However, the mechanism explaining how these cells get there (whether because of local induction or homing after induction at other sites) and the role these cells might play during active infection is not yet clear.

Novel Method Enabling the Use of Cryopreserved Primary Acute Myeloid Leukemia Cells in Functional Drug Screens

The ability to assess antileukemic drug activity on primary patient samples is a powerful tool in determining potential drug targets and selection of therapeutic agents with biological and functional rationale. We previously established small molecule inhibitor screens for use on freshly isolated leukemia cells for this purpose. Here we describe a method that produces functional small molecule inhibitor screening results using cryopreserved primary acute myeloid leukemia cells. This method was established to take advantage of biorepositories containing archival material, such as those established by the Children's Oncology Group, and to enable validation of potential pathway dependencies uncovered by genomic analysis. Various conditions used to thaw and culture cryopreserved specimens were assessed for effect on viability, differentiation, and the ability to recapitulate sensitivity results obtained on fresh samples. The most reproducible results were obtained by quick-thawing and culturing samples in cytokine rich media before performing drug screens. Our data suggest that cytokine-enriched media aids in maintaining the viability and numbers required to perform functional analysis on cryopreserved leukemia cells. This method can aid in producing informative data on therapeutic targeting and precision medicine efforts in leukemia by making use of biorepositories and bio banks.

Circulating B cells in type 1 diabetics exhibit fewer maturation-associated phenotypes

Although autoantibodies have been used for decades as diagnostic and prognostic markers in type 1 diabetes (T1D), further analysis of developmental abnormalities in B cells could reveal tolerance checkpoint defects that could improve individualized therapy. To evaluate B cell developmental progression in T1D, immunophenotyping was used to classify circulating B cells into transitional, mature naïve, mature activated, and resting memory subsets. Then each subset was analyzed for the expression of additional maturation-associated markers. While the frequencies of B cell subsets did not differ significantly between patients and controls, some T1D subjects exhibited reduced proportions of B cells that expressed transmembrane activator and CAML interactor (TACI) and Fas receptor (FasR). Furthermore, some T1D subjects had B cell subsets with lower frequencies of class switching. These results suggest circulating B cells exhibit variable maturation phenotypes in T1D. These phenotypic variations may correlate with differences in B cell selection in individual T1D patients.

Influence of Plasma Cell Niche Factors on the Recruitment and Maintenance of IRF4hi Plasma Cells and Plasmablasts in Vaccinated, Simian Immunodeficiency Virus-Infected Rhesus Macaques with Low and High Viremia

In a recent study, we found that protection following simian immunodeficiency virus (SIV) exposure correlated with rectal plasma cell frequency in vaccinated female rhesus macaques. We sought to determine if the same macaques maintained high mucosal plasma cell frequencies postinfection and if this translated to reduced viremia. Although delayed SIV acquisition did not predict subsequent viral control, alterations existed in the distribution of plasma cells and plasmablasts between macaques that exhibited high or low viremia. Flow cytometric analysis of cells from rectal biopsy specimens, bone marrow, and mesenteric lymph nodes of vaccinated infected, unvaccinated infected, and uninfected macaques identified two main IRF4^hi subsets of interest: CD138⁺ plasma cells, and CD138^- plasmablasts. In rectal tissue, plasma cell frequency positively correlated with plasma viremia and unvaccinated macaques had increased plasma cells and plasmablasts compared to vaccinated animals. Likewise, plasmablast frequency in the mesenteric lymph node correlated with viremia. However, in bone marrow, plasmablast frequency negatively correlated with viremia. Accordingly, low-viremic macaques had a higher frequency of both bone marrow IRF4^hi subsets than did animals with high viremia. Significant reciprocal relationships between rectal and bone marrow plasmablasts suggested that efficient trafficking to the bone marrow as opposed to the rectal mucosa was linked to viral control. mRNA expression analysis of proteins involved in establishment of plasma cell niches in sorted bone marrow and rectal cell populations further supported this model and revealed differential mRNA expression patterns in these tissues.

IMPORTANCE

As key antibody producers, plasma cells and plasmablasts are critical components of vaccine-induced immunity to human immunodeficiency virus type 1 (HIV-1) in humans and SIV in the macaque model; however, few have attempted to examine the role of these cells in viral suppression postinfection. Our results suggest that plasmablast trafficking to and retention in the bone marrow play a previously unappreciated role in viral control and contrast the potential contribution of mucosal plasma cells to mediate protection at sites of infection with that of bone marrow plasmablasts and plasma cells to control viremia during chronic infection. Manipulation of niche factors influencing the distribution and maintenance of these critical antibody-secreting cells may serve as potential therapeutic targets to enhance antiviral responses postvaccination and postinfection.