Transient reduction in IgA+ and IgG+ memory B cell numbers in young EBV-seropositive children: the Generation R Study

Multiple sclerosis risk variants influence the peripheral B-cell compartment early in life in the general population

BACKGROUND AND PURPOSE

Multiple sclerosis (MS) is associated with abnormal B-cell function, and MS genetic risk alleles affect multiple genes that are expressed in B cells. However, how these genetic variants impact the B-cell compartment in early childhood is unclear. In the current study, we aim to assess whether polygenic risk scores (PRSs) for MS are associated with changes in the blood B-cell compartment in children from the general population.

METHODS

Six-year-old children from the population-based Generation R Study were included. Genotype data were used to calculate MS-PRSs and B-cell subset-enriched MS-PRSs, established by designating risk loci based on expression and function. Analyses of variance were performed to examine the effect of MS-PRSs on total B-cell numbers (n = 1261) as well as naive and memory subsets (n = 675).

RESULTS

After correction for multiple testing, no significant associations were observed between MS-PRSs and total B-cell numbers and frequencies of subsets therein. A naive B-cell-MS-PRS (n = 26 variants) was significantly associated with lower relative, but not absolute, naive B-cell numbers (p = 1.03 × 10^-4 and p = 0.82, respectively), and higher frequencies and absolute numbers of CD27⁺ memory B cells (p = 8.83 × 10^-4 and p = 4.89 × 10^-3 , respectively). These associations remained significant after adjustment for Epstein-Barr virus seropositivity and the HLA-DRB1*15:01 genotype.

CONCLUSIONS

The composition of the blood B-cell compartment is associated with specific naive B-cell-associated MS risk variants during childhood, possibly contributing to MS pathophysiology later in life. Cell subset-specific PRSs may offer a more sensitive tool to define the impact of genetic risk on the immune system in diseases such as MS.

[Epstein-Barr viral infection is a global epidemiological problem]

The number of studies devoted to Epstein-Barr viral infection (EBV infection) has been growing in recent years. However, they all relate to the clinical aspects of this problem. Epidemiology issues remain practically unexplored. A review of domestic and foreign publications has shown that at the present stage there is a high intensity of the epidemic process of EBV infection both in Russia and abroad. The main indicators of unfavorable epidemiological situation are the ubiquitous spread of the pathogen and the increase in the incidence of infectious mononucleosis in recent years. The deterioration of the epidemic situation of EBV infection is influenced by changes in the immunological reactivity of various population groups due to the spread of HIV, HBV, HCV, the causative agent of tuberculosis and SARS-CoV-2. The above makes it possible to classify the problem as a global one and determines the need for the rapid implementation of the system of epidemiological surveillance of EBV infection and optimization of the complex of preventive and anti-epidemic measures. Reducing the burden of EBV is possible only with the consolidated participation of specialists of various profiles.

The association of Epstein-Barr virus infection with CXCR3+ B-cell development in multiple sclerosis: impact of immunotherapies

Epstein–Barr virus (EBV) infection of B cells is associated with increased multiple sclerosis (MS) susceptibility. Recently, we found that CXCR3‐expressing B cells preferentially infiltrate the CNS of MS patients. In chronic virus‐infected mice, these types of B cells are sustained and show increased antiviral responsiveness. How EBV persistence in B cells influences their development remains unclear. First, we analyzed ex vivo B‐cell subsets from MS patients who received autologous bone marrow transplantation (n = 9), which is often accompanied by EBV reactivation. The frequencies of nonclass‐switched and class‐switched memory B cells were reduced at 3–7 months, while only class‐switched B cells returned back to baseline at 24–36 months posttransplantation. At these time points, EBV DNA load positively correlated to the frequency of CXCR3⁺, and not CXCR4⁺ or CXCR5⁺, class‐switched B cells. Second, for CXCR3⁺ memory B cells trapped within the blood of MS patients treated with natalizumab (anti‐VLA‐4 antibody n = 15), latent EBV infection corresponded to enhanced in vitro formation of anti‐EBNA1 IgG‐secreting plasma cells under GC‐like conditions. These findings imply that EBV persistence in B cells potentiates brain‐homing and antibody‐producing CXCR3⁺ subsets in MS.

The influence of Epstein-Barr virus and cytomegalovirus on childhood respiratory health: A population-based prospective cohort study

Background

Epstein‐Barr virus (EBV) and cytomegalovirus (CMV) infection are common in early childhood. CMV infection favours a T‐helper‐1 and EBV infection a T‐helper‐2 cell response, possibly leading to disbalanced T‐helper cell response, and subsequent risk of asthma or atopy.

Objective

To study the associations of EBV and CMV with lung function, asthma and inhalant allergic sensitization at school age.

Methods

This study among 3546 children was embedded in a population‐based prospective cohort. At age 6 years, serum IgG levels against EBV and CMV were measured by ELISA. At age 10 years, lung function was measured by spirometry, asthma by questionnaire and inhalant allergic sensitization by skin prick test.

Results

Unadjusted models showed that seropositivity for EBV was associated with a higher FEV₁ and FEF₇₅ (Z‐score difference (95% CI): 0.09 (0.02, 0.16) and 0.09 (0.02, 0.15)), while seropositivity for CMV was not. Specific combinations of viruses showed that seropositivity for EBV was only associated with FEV₁ and FEF₇₅ in the presence of seropositivity for CMV (0.12 (0.04, 0.20)) and 0.08 (0.01, 0.15)). Seropositivity for CMV in the absence of seropositivity for EBV was associated with an increased risk of inhalant allergic sensitization (OR (95% CI): 1.31 (1.02, 1.68)). All effect estimates attenuated into non‐significant mainly after adjustment for child's ethnicity. Seropositivity for EBV or CMV was not associated with asthma.

Conclusions and Clinical Relevance

Associations of EBV and CMV infections in early childhood with school‐age lung function and inhalant allergic sensitization are explained by ethnicity, or sociodemographic and lifestyle‐related factors.

Immune system development varies according to age, location, and anemia in African children

Children from low- and middle-income countries, where there is a high incidence of infectious disease, have the greatest need for the protection afforded by vaccination, but vaccines often show reduced efficacy in these populations. An improved understanding of how age, infection, nutrition, and genetics influence immune ontogeny and function is key to informing vaccine design for this at-risk population. We sought to identify factors that shape immune development in children under 5 years of age from Tanzania and Mozambique by detailed immunophenotyping of longitudinal blood samples collected during the RTS,S malaria vaccine phase 3 trial. In these cohorts, the composition of the immune system is dynamically transformed during the first years of life, and this was further influenced by geographical location, with some immune cell types showing an altered rate of development in Tanzanian children compared to Dutch children enrolled in the Generation R population-based cohort study. High-titer antibody responses to the RTS,S/AS01E vaccine were associated with an activated immune profile at the time of vaccination, including an increased frequency of antibody-secreting plasmablasts and follicular helper T cells. Anemic children had lower frequencies of recent thymic emigrant T cells, isotype-switched memory B cells, and plasmablasts; modulating iron bioavailability in vitro could recapitulate the B cell defects observed in anemic children. Our findings demonstrate that the composition of the immune system in children varies according to age, geographical location, and anemia status.

Differences in Systemic IgA Reactivity and Circulating Th Subsets in Healthy Volunteers With Specific Microbiota Enterotypes

Changes in the intestinal microbiota have been associated with the development of immune-mediated diseases in humans. Additionally, the introduction of defined bacterial species into the mouse intestinal microbiota has been shown to impact on the adaptive immune response. However, how much impact the intestinal microbiota composition actually has on regulating adaptive immunity remains poorly understood. Therefore, we studied aspects of the adaptive immunity in healthy adults possessing distinct intestinal microbiota profiles. The intestinal microbiota composition was determined via Illumina sequencing of bacterial 16S rRNA genes extracted from the feces of 35 individuals. Blood B-cell and T-cell subsets from the same individuals were studied using flow cytometry. Finally, the binding of fecal and plasma Immunoglobulin A (IgA) to intestinal bacteria (associated with health and disease) Bacteroides fragilis, Prevotella copri, Bifidobacterium longum, Clostridium difficile, and Escherichia coli was analyzed using ELISA. Unsupervised clustering of microbiota composition revealed the presence of three clusters within the cohort. Cluster 1 and 2 were similar to previously-described enterotypes with a predominance of Bacteroides in Cluster 1 and Prevotella in Cluster 2. The bacterial diversity (Shannon index) and bacterial richness of Cluster 3 was significantly higher than observed in Clusters 1 and 2, with the Ruminococacceae tending to predominate. Within circulating B- and T-cell subsets, only Th subsets were significantly different between groups of distinct intestinal microbiota. Individuals of Cluster 3 have significantly fewer Th17 and Th22 circulating cells, while Th17.1 cell numbers were increased in individuals of Cluster 1. IgA reactivity to intestinal bacteria was higher in plasma than feces, and individuals of Cluster 1 had significant higher plasma IgA reactivity against B. longum than individuals of Cluster 2. In conclusion, we identified three distinct fecal microbiota clusters, of which two clusters resembled previously-described "enterotypes". Global T-cell and B-cell immunity seemed unaffected, however, circulating Th subsets and plasma IgA reactivity were significantly different between Clusters. Hence, the impact of intestinal bacteria composition on human B cells, T cells and IgA reactivity appears limited in genetically-diverse and environmentally-exposed humans, but can skew antibody reactivity and Th cell subsets.

Epstein-Barr Virus, but Not Cytomegalovirus, Latency Accelerates the Decay of Childhood Measles and Rubella Vaccine Responses-A 10-Year Follow-up of a Swedish Birth Cohort

BACKGROUND

Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are ubiquitous and persistent herpesviruses commonly acquired during childhood. Both viruses have a significant impact on the immune system, especially through mediating the establishment of cellular immunity, which keeps these viruses under control for life. Far less is known about how these viruses influence B-cell responses.

OBJECTIVES

To evaluate the impact of latent EBV and CMV infection on rubella- and measles-specific antibody responses as well as on the B-cell compartment in a prospective birth cohort followed during the first 10 years of life.

METHODS

IgG titers against rubella and measles vaccines were measured in plasma obtained from the same donors at 2, 5, and 10 years of age. Peripheral B-cell subsets were evaluated ex vivo at 2 and 5 years of age. Factors related to optimal B-cell responses including IL-21 and CXCL13 levels in plasma were measured at all-time points.

RESULTS

EBV carriage in the absence of CMV associated with an accelerated decline of rubella and measles-specific IgG levels (p = 0.003 and p = 0.019, respectively, linear mixed model analysis), while CMV carriage in the absence of EBV associated with delayed IgG decay over time for rubella (p = 0.034). At 5 years of age, EBV but not CMV latency associated with a lower percentage of plasmablasts, but higher IL-21 levels in the circulation.

CONCLUSION

Our findings suggest that EBV carriage in the absence of CMV influences the B-cell compartment and the dynamics of antibody responses over time during steady state in the otherwise healthy host.