Excess BAFF Alters NR4As Expression Levels and Breg Function of Human Precursor-like Marginal Zone B-Cells in the Context of HIV-1 Infection.

We have reported excess B-cell activating factor (BAFF) in the blood of HIV-infected progressors, which was concomitant with increased frequencies of precursor-like marginal zone (MZp) B-cells, early on and despite antiretroviral therapy (ART). In controls, MZp possess a strong B-cell regulatory (Breg) potential. They highly express IL-10, the orphan nuclear receptors (NR)4A1, NR4A2 and NR4A3, as well as the ectonucleotidases CD39 and CD73, all of which are associated with the regulation of inflammation. Furthermore, we have shown MZp regulatory function to involve CD83 signaling. To address the impact of HIV infection and excessive BAFF on MZp Breg capacities, we have performed transcriptomic analyses by RNA-seq of sorted MZp B-cells from the blood of HIV-infected progressors. The Breg profile and function of blood MZp B-cells from HIV-infected progressors were assessed by flow-cytometry and light microscopy high-content screening (HCS) analyses, respectively. We report significant downregulation of NR4A1, NR4A2, NR4A3 and CD83 gene transcripts in blood MZp B-cells from HIV-infected progressors when compared to controls. NR4A1, NR4A3 and CD83 protein expression levels and Breg function were also downregulated in blood MZp B-cells from HIV-infected progressors and not restored by ART. Moreover, we observe decreased expression levels of NR4A1, NR4A3, CD83 and IL-10 by blood and tonsillar MZp B-cells from controls following culture with excess BAFF, which significantly diminished their regulatory function. These findings, made on a limited number of individuals, suggest that excess BAFF contributes to the alteration of the Breg potential of MZp B-cells during HIV infection and possibly in other situations where BAFF is found in excess.

Sexually Transmitted and Blood-Borne Infections in Pregnant Women and Adverse Pregnancy Outcomes.

OBJECTIVES: To analyze risk factors for the presence of sexually transmitted and blood-borne infections (STBBIs) in pregnancy and to determine whether pregnant women with STBBIs are more likely to experience adverse pregnancy outcomes. METHODS: This retrospective cohort study involved analyzing the electronic records of 3460 pregnant women followed at Sainte-Justine Hospital in Montréal, Québec, between March 2017 and January 2019. An outcome is defined as a pregnancy where the woman has at least one positive laboratory result for chlamydia, gonorrhea, syphilis, hepatitis B, or hepatitis C (i.e., has one or multiple STBBIs). We performed a logistic regression analysis to determine adjusted odds ratios (aORs) for the risk factors of STBBIs in pregnant women. RESULTS: We identified 84 positive STBBI cases, an overall prevalence of 2.4% (95% CI 1.9-2.9). A logistic regression analysis showed the following factors to be significantly associated with the presence of STBBIs in pregnancy: age <20 years (OR 4.75; 95% CI 1.89-11.96), age 20-29 years (OR 2.38; 95% CI 1.37-4.14), Afro-Caribbean origin (OR 4.12; 95% CI 1.83-9.27), other non-Caucasian origin (OR 2.38; 95% CI 1.20-4.70), and history of STBBIs (OR 2.33; 95% CI 1.02-5.36). STBBIs were not significantly associated with social and material deprivation indices nor were they associated with low birth weight or preterm birth. CONCLUSION: This study shows age <20 years, age 20-29 years, Afro-Caribbean or other non-Caucasian origin and history of STBBIs to be risk factors for the presence of STBBIs in pregnancy. These results will allow us to propose interventions to reduce STBBIs in women with common risk factors as part of a comprehensive approach to perinatal care.

NR4A Expression by Human Marginal Zone B-Cells.

We have previously characterized a human blood CD19+CD1c+IgM+CD27+CD21loCD10+ innate-like B-cell population, which presents features shared by both transitional immature and marginal zone (MZ) B-cells, named herein "precursor-like" MZ B-cells. B-cells with similar attributes have been associated with regulatory potential (Breg). In order to clarify this issue and better characterize this population, we have proceeded to RNA-Seq transcriptome profiling of mature MZ and precursor-like MZ B-cells taken from the blood of healthy donors. We report that ex vivo mature MZ and precursor-like MZ B-cells express transcripts for the immunoregulatory marker CD83 and nuclear receptors NR4A1, 2, and 3, known to be associated with T-cell regulatory (Treg) maintenance and function. Breg associated markers such as CD39 and CD73 were also expressed by both populations. We also show that human blood and tonsillar precursor-like MZ B-cells were the main B-cell population to express elevated levels of CD83 and NR4A1-3 proteins ex vivo and without stimulation. Sorted tonsillar precursor-like MZ B-cells exerted regulatory activity on autologous activated CD4+ T-cells, and this was affected by a CD83 blocking reagent. We believe these observations shed light on the Breg potential of MZ populations, and identify NR4A1-3 as potential Breg markers, which as for Tregs, may be involved in stabilization of a regulatory status. Since expression and activity of these molecules can be modulated therapeutically, our findings may be useful in strategies aiming at modulation of Breg responses.