Epstein-Barr virus and cytomegalovirus are differentially associated with numbers of cytokine-producing cells and early atopy

[Anything that can go wrong: cytotoxic cells and their control of Epstein-Barr virus]

Epstein-Barr virus (EBV) is an gamma of herpes virus affecting exclusively humans, was the first oncogenic virus described and is associated with over seven different cancers. Curiously, the exchange of genes during viral infections has enabled the evolution of other cellular organisms, favoring new functions and the survival of the host. EBV has been co-evolving with mammals for hundreds of millions of years, and more than 95% of adults have been infected in one moment of their life. The infection is acquired primarily during childhood, in most cases as an asymptomatic infection. However, during adolescence or young adulthood, around 10 to 30% develop infectious mononucleosis. The NK and CD8+ T cells are the cytotoxic cells of the immune system that focus on antiviral responses. Importantly, an essential role of NK and CD8+ T cells has been demonstrated during the control and elimination of EBV-infected cells. Nonetheless, when the cytotoxic function of these cells is compromised, the infection increases the risk of developing lymphoproliferative diseases and cancer, often fatal. In this review, we delineate EBV infection and the importance of cytotoxic responses by NK and CD8+ T cells during the control and elimination of EBV-infected cells. Furthermore, we briefly discuss the main inborn errors of immunity that compromise cytotoxic responses by NK and CD8+ T cells, and how this scenario affects the antiviral response during EBV infection. Finally, we conclude the review by underlying the need for an effective EBV vaccine capable of preventing infection and the consequent development of malignancies and autoimmune diseases.

Four-Parameter FluoroSpot Assay Reveals That the Varicella Zoster Virus Elicits a Robust Memory T Cell IL-10 Response throughout Childhood

During childhood, the composition and function of the T cell compartment undergoes significant changes. In healthy individuals, primary infection with herpesviruses is followed by latency, and occasional subclinical reactivation ensures transmission and contributes to an emerging pool of memory T cells. In immunocompromised individuals, herpesviruses can be life threatening. However, knowledge about the spectrum of virus-specific cytokine responses is limited. Here, we investigated peripheral blood mononuclear cells (PBMCs) from children with differential carrier statuses for cytomegalovirus (CMV), Epstein-Barr virus (EBV), and varicella zoster virus (VZV) (n = 32, age 1 to 17 years). We examined memory T cell subsets as well as IFN-γ-, IL-10-, IL-17A-, and IL-22-producing T cells after polyclonal activation or stimulation with viral peptides using flow cytometry and a 4-parameter FluoroSpot assay. Age and herpesvirus carriage influenced the size of the memory T cell subsets. A positive association between age and the number of IFN-γ-, IL-17A- and IL-22-producing T cells was found following polyclonal activation. For CMV, age was positively associated with IL-17A spot-forming cells (SFC), while for VZV, age was negatively associated with IL-22 and positively associated with IFN-γ SFC. Upon activation with CMV, VZV, and EBV peptides, IFN-γ SFCs dominated. Notably, VZV responses were characterized by a higher IL-10 SFC population compared to both CMV and EBV. Our findings suggest that cytokine responses vary across herpesvirus-type-specific memory T cells and may more adequately reflect their composition. An observed deviation between polyclonal and herpesvirus-specific T cell cytokine responses in children needs to be considered when interpreting the associations between herpesvirus carrier status and bulk T cell reactivity. In summary, these findings may have implications for the treatment of immunocompromised patients. IMPORTANCE Infection with herpesviruses accounts for 35 to 40 billion human cases worldwide. Despite this, little is known about how herpesviruses shape the immune system in the asymptomatic carrier. Particularly in children, primary infection is connected to no or mild symptoms ahead of latency for life. Most research on cellular responses against herpesviruses focuses on inflammatory cytokines associated with antiproliferative and antitumor mechanisms and not the spectrum of cytokine responses in healthy humans. This study investigated four divergent cytokine-producing T cell responses to herpesviruses, reflecting different immunological functions. Three common childhood herpesviruses were selected: Epstein-Barr virus, cytomegalovirus, and varicella-zoster virus. Curiously, not all viruses induced the same pattern of cytokines. Varicella-zoster responses were characterized by IL-10, which is considered regulatory. Besides broadening understanding of responses to herpesviruses, our results raise the possibility that reactivation of varicella-zoster may be counterproductive in cancer treatment through the action of IL-10-producing T-cells.

Association of IgE elevation with blood group in COVID-19 patients

Aim : All parameters that are thought to be efficient in getting sick and follow-up of the disease should be investigated because of COVID-19 disease has serious consequences. The aim of this study was to investigate whether there is a relationship between the AB0 blood group with Rh factor systems and the frequency of catching COVID-19 infection and between IgE elevation according to blood groups and COVID-19 positivity. Material and Method: Blood groups and IgE levels of the control group (2690 patients) were compared retrospectively with 7300 patients who were admitted to our hospital between March 10, 2020, and March 31, 2021, and confirmed as COVID-19 positive with viral ribonucleic acid reverse transcriptase-polymerase chain reaction (RT-PCR). Results: It was found that among the blood groups, the highest COVID-19 positivity belonged to the A blood group (46.17%) and the lowest belonged to the AB blood group (9.04%). The increase in IgE elevation was found statistically significant in COVID-19 positive patients (P

Early-life cytomegalovirus infection is associated with gut microbiota perturbations and increased risk of atopy

BACKGROUND

The "old friends" hypothesis posits that reduced exposure to previously ubiquitous microorganisms is one factor involved in the increased rates of allergic diseases. Cytomegalovirus (CMV) may be one of the "old friends" hypothesized to help prevent allergic diseases. We sought to elucidate whether early-life CMV infection is associated with childhood atopy via perturbations of the gut microbiota.

METHODS

Participants were recruited from a population-based birth cohort (CHILD study) and followed prospectively until age 5 years in four Canadian cities. A total of 928 participants provided stool microbiome data, urine for CMV testing, skin prick tests, and questionnaire-based detailed environmental exposures. Cytomegalovirus infection was assessed in the first year of life while the main outcome was defined by persistent sensitization to any allergen at ages 1, 3, and 5 years.

RESULTS

Early CMV infection was associated with increased beta and decreased alpha diversity of the gut microbiota. Both changes in diversity measures and early CMV infection were associated with persistent allergic sensitization at age 5 years (aOR = 2.08; 95% CI: 1, 4.33). Mediation analysis demonstrated that perturbation of gut microbial composition explains 30% of the association.

CONCLUSIONS

Early-life CMV infection is associated with an alteration in the intestinal microbiota, which mediates the effect of the infection on childhood atopy. This work indicates that preventing CMV infection would not put children at increased risk of developing atopy. Rather, a CMV vaccine, in addition to preventing CMV-associated morbidity and mortality, might reduce the risk of childhood allergic diseases.

Common Childhood Viruses and Pubertal Timing: The LEGACY Girls Study

Earlier pubertal development is only partially explained by childhood body mass index; the role of other factors, such as childhood infections, is less understood. Using data from the LEGACY Girls Study (North America, 2011-2016), we prospectively examined the associations between childhood viral infections (cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV) 1, HSV2) and pubertal timing. We measured exposures based on seropositivity in premenarcheal girls (n = 490). Breast and pubic hair development were classified based on mother-reported Tanner Stage (TS) (TS2+ compared with TS1), adjusting for age, body mass index, and sociodemographic factors. The average age at first blood draw was 9.8 years (standard deviation, 1.9 years). The prevalences were 31% CMV+, 37% EBV+, 14% HSV1+, 0.4% HSV2+, and 16% for both CMV+/EBV+ coinfection. CMV+ infection without coinfection was associated with developing breasts an average of 7 months earlier (hazard ratio (HR) = 2.12, 95% confidence interval (CI): 1.32, 3.40). CMV infection without coinfection and HSV1 and/or HSV2 infection were associated with developing pubic hair 9 months later (HR = 0.41, 95% CI: 0.24, 0.71, and HR = 0.42, 95% CI: 0.22, 0.81, respectively). Infection was not associated with menarche. If replicated in larger cohorts with blood collection prior to any breast development, this study supports the hypothesis that childhood infections might play a role in altering pubertal timing.

Heterogeneous associations of polyomaviruses and herpesviruses with allergy-related phenotypes in childhood

BACKGROUND

Evidence suggests a complex interplay between infections and allergic diseases.

OBJECTIVE

To explore the association of 14 common viruses with eczema, asthma, and rhinoconjunctivitis in childhood.

METHODS

We used cross-sectional (n = 686) and prospective (n = 440) data from children participating in the Rhea birth cohort. Immunoglobulin G to polyomaviruses (BK polyomavirus, JC polyomavirus, KI polyomavirus [KIPyV], WU polyomavirus [WUPyV], human polyomavirus 6, human polyomavirus 7, Trichodysplasia spinulosa polyomavirus, Merkel cell polyomavirus, human polyomavirus 9, and human polyomavirus 10) and herpesviruses (Epstein-Barr virus, Cytomegalovirus, Herpes simplex virus-1, Herpes simplex virus-2) were measured at age 4 years by fluorescent bead-based multiplex serology. Definitions of eczema, asthma, and rhinoconjunctivitis at ages 4 and 6 years were based on questionnaires. Mediation of the associations by immune biomarkers was tested.

RESULTS

Less likely to have eczema at age 4 years were KIPyV-seropositive (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.27-0.82) and human polyomavirus 6 (OR, 0.44; 95% CI, 0.26-0.73) compared with their seronegative counterparts. Seropositivity to Epstein-Barr virus was negatively associated with eczema at age 4 years (OR, 0.39; 95% CI, 0.22-0.67) and 6 years (OR, 0.50; 95% CI, 0.25-0.99). Children with a higher burden of herpesviruses or of skin polyomaviruses had the lowest odds of eczema at age 4 years. Higher odds for asthma at age 4 years were found for WUPyV-seropositive children (OR, 3.98; 95% CI, 1.38-11.51), and for children seropositive to both respiratory polyomaviruses (KIPyV and WUPyV) (OR, 7.35; 95% CI, 1.66-32.59) compared with children seronegative to both. No associations were observed for rhinoconjunctivitis. There was no evidence of mediation by immune biomarkers.

CONCLUSION

A heterogeneous pattern of infections and allergic diseases was observed with common infections associated with a decreased eczema risk and an increased asthma risk in children.

Beta and Gamma Human Herpesviruses: Agonistic and Antagonistic Interactions with the Host Immune System

Viruses are the most abundant and diverse biological entities in the planet. Historically, our main interest in viruses has focused on their pathogenic role, recognized by pandemics that have decimated the world population. However, viral infections have also played a major role in the evolution of cellular organisms, both through interchanging of genes with novel functions and shaping the immune system. Examples abound of infections that seriously compromise the host integrity, but evidence of plant and insect viruses mutualistic relationships have recently surfaced in which infected hosts are better suited for survival, arguing that virus-host interactions are initially parasitic but become mutualistic over years of co-evolution. A similar mutual help scenario has emerged with commensal gut bacteria. EBV is a herpesvirus that shares more than a hundred million years of co-evolution with humans, today successfully infecting close to 100% of the adult world population. Infection is usually acquired early in childhood persisting for the host lifetime mostly without apparent clinical symptoms. Disturbance of this homeostasis is rare and results in several diseases, of which the best understood are infectious mononucleosis and several EBV-associated cancers. Less understood are recently found inborn errors of the immune system that result in primary immunodeficiencies with an increased predisposition almost exclusive to EBV-associated diseases. Puzzling to these scenarios of broken homeostasis is the co-existence of immunosuppression, inflammation, autoimmunity and cancer. Homologous to EBV, HCMV, HHV-6 and HHV-7 are herpesviruses that also latently infect most individuals. Several lines of evidence support a mutualistic equilibrium between HCMV/EBV and hosts, that when altered trigger diseases in which the immune system plays a critical role. Interestingly, these beta and gamma herpesviruses persistently infect all immune lineages and early precursor cells. In this review, we will discuss the evidence of the benefits that infection of immune cells with these herpesviruses brings to the host. Also, the circumstances in which this positive relationship is broken, predisposing the host to diseases characterized by an abnormal function of the host immune system.

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.

Microbes and Viruses Are Bugging the Gut in Celiac Disease. Are They Friends or Foes?

The links between microorganisms/viruses and autoimmunity are complex and multidirectional. A huge number of studies demonstrated the triggering impact of microbes and viruses as the major environmental factors on the autoimmune and inflammatory diseases. However, growing evidences suggest that infectious agents can also play a protective role or even abrogate these processes. This protective crosstalk between microbes/viruses and us might represent a mutual beneficial equilibrium relationship between two cohabiting ecosystems. The protective pathways might involve post-translational modification of proteins, decreased intestinal permeability, Th1 to Th2 immune shift, induction of apoptosis, auto-aggressive cells relocation from the target organ, immunosuppressive extracellular vesicles and down regulation of auto-reactive cells by the microbial derived proteins. Our analysis demonstrates that the interaction of the microorganisms/viruses and celiac disease (CD) is always a set of multidirectional processes. A deeper inquiry into the CD interplay with Herpes viruses and Helicobacter pylori demonstrates that the role of these infections, suggested to be potential CD protectors, is not as controversial as for the other infectious agents. The outcome of these interactions might be due to a balance between these multidirectional processes.

Herpesvirus Infections and Transglutaminase Type 2 Antibody Positivity in Childhood: The Generation R Study

OBJECTIVES

Persistent viral infections have been implicated in the etiology of autoimmune diseases in adulthood, but it is not known whether herpesviruses are associated with the development of celiac disease autoimmunity in childhood. We assessed whether herpesvirus infections are associated with transglutaminase type 2 antibody (TG2A) concentrations in children at 6 years of age.

METHODS

The present study was embedded within a population-based prospective cohort study. Serum immunoglobulin G levels against Epstein-Barr virus, cytomegalovirus (CMV), and herpes simplex virus type 1 were measured by enzyme-linked immunosorbent assay , and TG2A concentrations with fluorescence enzyme immunoassay in 4420 children at 6 years of age. Children were categorized based on TG2A concentrations into negative (<7 U/mL), positive (≥7-70 U/mL), and strongly positive (≥70 U/mL), that is, 10 times upper limit normal.

RESULTS

Fifty-nine children (1.3%) were TG2A positive, and of these 31 (53%) had concentrations 70 U/mL or more. Children with TG2A concentrations 70 U/mL or more were less often infected with CMV (adjusted odds ratio (aOR) 0.38, 95% CI 0.14-0.98, P = 0.04) and with any of the 3 viruses (aOR 0.38, 95% CI 0.18-0.78, P < 0.01) than children with TG2A negative concentrations. In addition, children with TG2A concentrations 70 U/mL or more were less often infected with 2 or more viruses than children with TG2A negative concentrations (aOR 0.15, 95% CI 0.03-0.65, P = 0.01).

CONCLUSIONS

Both CMV single infection and combined CMV, Epstein-Barr virus and/or herpes simplex virus type 1 infections are inversely associated with strongly TG2A positivity. This may indicate a protective effect of herpesvirus infections in the pathogenesis of celiac disease autoimmunity.

Associations between EBV and CMV Seropositivity, Early Exposures, and Gut Microbiota in a Prospective Birth Cohort: A 10-Year Follow-up

Early-life infections with persistent Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are delayed in affluent countries, probably due to alterations in early environmental exposures, such as maternal age, siblings, and day-care attendance. We have previously reported that the timing of EBV and CMV contraction is related both to allergic sensitization and changes in functional competence of immune cells, while the presence/absence of lactobacilli [Lactobacillus (L.) casei, L. paracasei, and L. rhamnosus] or Staphylococcus (S.) aureus in feces is related to the risk for allergy. Here, we used the same prospective longitudinal birth cohort of children to investigate early-life environmental exposures and their influence on EBV and CMV contraction over time. Since gut microbes also belong to this category of early exposures, we investigated their association with herpesvirus contraction. Our results show that these two viruses are acquired with different kinetics and that EBV and CMV seroprevalence at 10 years of age was 47 and 57%, respectively. We also observed that a delayed EBV or CMV infection was associated with older maternal age [time ratio (TR) 1.14, 95% confidence interval (CI) 1.07-1.21, P adj < 0.001 and TR 1.09, CI 1.03-1.16, P adj = 0.008, respectively]. Further, we present the novel finding that S. aureus colonization reduced the time to CMV acquisition (TR 0.21, CI 0.06-0.78, P adj = 0.02). Together, these findings suggest that there is a relationship between timing of herpesvirus acquisition and early-life immune modulating exposures, which interestingly also includes the early infant gut microbiota.

Cytomegalovirus- and Epstein-Barr Virus-Induced T-Cell Expansions in Young Children Do Not Impair Naive T-cell Populations or Vaccination Responses: The Generation R Study

BACKGROUND

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) induce effector memory T-cell expansions, which are variable and potentially depend on the age at primary exposure and coinfections. We evaluated the T-cell compartment and herpesvirus infections in 6-year-old children.

METHODS

T-cell subsets and immunoglobulin G seropositivity for CMV, EBV, herpes-simplex virus 1, and varicella-zoster virus were studied in 1079 6-year-old children. A random subgroup of 225 children was evaluated for CMV and EBV seropositivity before 2 years of age and for vaccination responses against measles and tetanus.

RESULTS

CMV and EBV infections were associated with significant expansions of CD27(-) and CD27(+) effector memory T cells, respectively. These expansions were enhanced in CMV-EBV-coinfected children and were independent of varicella-zoster virus or herpes-simplex virus 1 coinfection. Naive and central memory T-cell numbers were not affected, nor were anti-tetanus and anti-measles immunoglobulin G levels. Children infected before 2 years of age showed smaller effector memory T-cell expansions than those infected between 2 and 6 years of age.

CONCLUSIONS

CMV- and EBV-related T-cell expansions do not impair naive T-cell numbers or maintenance of protective responses against nonrelated pathogens. Duration of infection was not directly related to larger expansions of effector memory T cells in children, suggesting that other mechanisms affect these expansions at later age.

Herpesvirus-associated acute urticaria: an age matched case-control study

Background

Acute and recurrent acute urticaria are often associated with multiple factors including infections and recent data suggest a role for herpesviruses.

Objective

To test the null hypothesis, that is, there is no association of herpesvirus infections with urticaria.

Methods

Thirty-seven patients between one month and 15 years of age were age matched to 37 controls who were healthy or had mild acute respiratory infections but without urticaria. Patients and controls were followed for 1 to 6 years. Diagnostic studies included DNA detection by real-time PCR for herpes simplex virus (HSV) types 1 and 2, Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus-6 (HHV-6). Tests for other infections included adenovirus, parvovirus B 19, respiratory syncytial virus, influenza A, Group A streptococci, rotavirus, and parasites.

Results

Specific infections were diagnosed in 26 of 37 cases and among 9 of 37 control children (P=0.0002). Single or concomitant herpesvirus infections occurred in 24 cases and in 4 controls (65% vs 11 %, p=0.0003). Cases had 10 HHV-6 infections, 8 CMV infections, 5 EBV infections, and 4 HSV-1 infections.

Conclusion

Herpesvirus infections are associated with acute or recurrent acute urticaria.

Cytomegalovirus-seropositive children show inhibition of in vitro EBV infection that is associated with CD8+CD57+ T cell enrichment and IFN-γ

EBV, a human herpesvirus, is commonly acquired during childhood and persists latently in B cells. EBV seropositivity has been connected to immunomodulatory effects such as altered T and NK cell functional responses as well as protection against early IgE sensitization; however, owing to the asymptomatic presentation during childhood little is known regarding the infection process in children of different ages. In this study, we used mononuclear cells from cord blood and from 2- and 5-y-old EBV-naive children for in vitro EBV infection. We show that the degree of EBV-induced B cell activation and expansion differs between age groups and in particular in relationship to IFN-γ production capacity. EBV infection induced redistribution between B cell subsets with enrichment of IgD(+)CD27(+) cells (commonly referred to as non-switched memory) in infected cord blood cell cultures, and of IgD(-)CD27(+) cells (switched memory) in cell cultures from older children. We also related results to serostatus to CMV, a persistent herpesvirus that can affect differentiation status of T and NK cells. As compared with CMV(-) children, the EBV-induced enrichment of IgD(-)CD27(+) B cells was significantly reduced in infected cell cultures from CMV(+) children. This effect was associated with high levels of IFN-γ and frequencies of highly mature CD8(+)CD57(+) T cells in CMV(+) children. Our results demonstrate that both a child's age and serostatus to CMV will have an impact on EBV-induced B cell activation and expansion, and they point to the ability of viruses with immunomodulatory functions, such as CMV, to affect immune responses within the host system.

Herpesviruses and the microbiome

The focus of this article will be to examine the role of common herpesviruses as a component of the microbiome of atopic patients and to review clinical observations suggesting that atopic patients might be predisposed to more severe and atypical herpes-related illness because their immune response is biased toward a TH2 cytokine profile. Human populations are infected with 8 herpesviruses, including herpes simplex virus HSV1 and HSV2 (also termed HHV1 and HHV2), varicella zoster virus (VZV or HHV3), EBV (HHV4), cytomegalovirus (HHV5), HHV6, HHV7, and Kaposi sarcoma-associated herpesvirus (termed KSV or HHV8). Herpesviruses are highly adapted to lifelong infection of their human hosts and thus can be considered a component of the human "microbiome" in addition to their role in illness triggered by primary infection. HSV1 and HSV2 infection and reactivation can present with more severe cutaneous symptoms termed eczema herpeticum in the atopic population, similar to the more severe eczema vaccinatum, and drug reaction with eosinophilia and systemic symptoms syndrome (DRESS) is associated with reactivation of HSV6 and possibly other herpesviruses in both atopic and nonatopic patients. In this review evidence is reviewed that primary infection with herpesviruses may have an atypical presentation in the atopic patient and conversely that childhood infection might alter the atopic phenotype. Reactivation of latent herpesviruses can directly alter host cytokine profiles through viral expression of cytokine-like proteins, such as IL-10 (EBV) or IL-6 (cytomegalovirus and HHV8), viral encoded and secreted siRNA and microRNAs, and modulation of expression of host transcription pathways, such as nuclear factor κB. Physicians caring for allergic and atopic populations should be aware of common and uncommon presentations of herpes-related disease in atopic patients to provide accurate diagnosis and avoid unnecessary laboratory testing or incorrect diagnosis of other conditions, such as drug allergy or autoimmune disease. Antiviral therapy and vaccines should be administered promptly when indicated clinically.

Early-life gut bacteria associate with IL-4-, IL-10- and IFN-γ production at two years of age

Microbial exposure early in life influences immune maturation and potentially also the development of immune-mediated disease. Here we studied early-life gut colonization in relation to cytokine responses at two years of age. Fecal samples were collected from infants during the first two months of life. DNA was extracted from the fecal samples and Bifidobacterium (B.) adolescentis, B. breve, B. bifidum, a group of lactobacilli (L. casei, L. paracasei and L. rhamnosus) as well as Staphylococcus (S.) aureus were detected with real time PCR. Peripheral mononuclear cells were stimulated with phytohaemagglutinin (PHA) and numbers of IL-4−, IL-10− and IFN-γ secreting cells were evaluated using ELISpot. We further stimulated peripheral blood mononuclear cells with bacterial supernatants in vitro and assessed the IL-4−, IL-10− and IFN-γ inducing capacity by flow cytometry and ELISA. Early S. aureus colonization associated with higher numbers of IL-4− (p = 0.022) and IL-10 (p = 0.016) producing cells at two years of age. In contrast to colonization with S. aureus alone, co-colonization with lactobacilli associated with suppression of IL-4− (p = 0.004), IL-10− (p = 0.004) and IFN-γ (p = 0.034) secreting cells. In vitro stimulations of mononuclear cells with bacterial supernatants supported a suppressive role of L. rhamnosus GG on S. aureus-induced cytokine responses. We demonstrate that the early gut colonization pattern associates with the PHA-induced cytokine profile at two years of age and our in vitro findings support that specific bacterial species influence the T helper cell subsets. This suggests that dysbiosis in the early microbiota may modulate the risk of developing inflammatory conditions like allergy.

Enveloped virus but not bacteria block IL-13 responses in human cord blood T cells in vitro

Infections that occur early in life may have a beneficial effect on the immune system and thereby reduce the risk of allergen sensitization and/or allergic disease. It is not yet clear to what extent specific virus and/or bacteria can mediate this effect. The purpose of this study was to assess the role of virus and bacteria in CD4⁺ T cell‐derived cytokine production in newborns. We compared the effects of five bacteria (Staphlococcus aureus, Escherichia coli, Clostridium difficile, Lactobacillus rhamnosus and Bifidobacterium bifidus) and seven virus (adenovirus, coronavirus, cytomegalovirus, herpes simplex virus, influenza virus, morbillivirus and poliovirus) on the Th1/Th2 cytokine production in mixed lymphocyte reactions using CD4⁺ T cells from cord blood cocultured with allogenic myeloid or plasmacytoid dendritic cells. When comparing the baseline cytokine production prior to microbial stimulation, we observed that cord plasmacytoid DC were stronger inducers of Th2 cytokines (IL‐5 and IL‐13) compared with cord myeloid DC and to adult DC. When adding microbes to these cultures, bacteria and virus differed in two major respects; Firstly, all enveloped viruses, but none of the bacteria, blocked Th2 (IL‐13) production by cord CD4⁺ cells. Secondly, all Gram‐positive bacteria, but none of the virus, induced IL‐12p40 responses, but the IL‐12p40 responses did not affect Th1 cytokine production (IFN‐γ). Instead, Th1 responses were correlated with the capacity to induce IFN‐α secretion, which in cord cells were induced by S. aureus and influenza virus alone. These data imply that enveloped virus can deviate Th2 responses in human cord T cells.

Chronic virus infections supress atopy but not asthma in a set of children from a large Latin American city: a cross-section study

Background

The prevalence of allergic diseases has increased over recent decades in affluent countries, but remains low in rural populations and some non-affluent countries. An explanation for these trends is that increased exposure to infections may provide protection against the development of allergy. In this work we investigated the association between exposure to viral infections in children living in urban Brazil and the prevalence of atopy and asthma.

Methods

School age children living in poor neighborhoods in the city of Salvador were studied. Data on asthma symptoms and relevant risk factors were obtained by questionnaire. Skin prick tests (SPTs) were performed to seven aeroallergens, and specific IgE was measured to four of these. Viral infections were determined by the presence of specific IgG in serum to Herpes simplex (HSV), Herpes zoster (HZV), Epstein-Barr (EBV), and Hepatitis A (HAV) viruses.

Results

A total of 644 (49.7%) children had at least one allergen-specific IgE> 0.35 kU/L and 489 (37.7%) had specific IgE> 0.70 kU/L. A total of 391 (30.2%) children were skin test positive (SPT+), and 295 (22.8%) children were asthmatic. The seroprevalence of viral infections was 88.9% for EBV, 55.4% for HSV, 45.5% for VZV and 17.5% for HAV. Negative associations were observed between SPT+ and HSV (OR = 0.64, CI = 0.51, 0.82) and EBV (OR = 0.63, CI = 0.44, 0.89) infections, but no associations were seen between viral infections and the presence of allergen-specific IgE or asthma.

Conclusion

These data do not support previous data showing a protective effect of HAV against atopy, but did show inverse associations between SPT+ (but not specific IgE+) and infections with HSV and EBV. These findings suggest that different viral infections may protect against SPT+ in different settings and may indicate an immunoregulatory role of such infections on immediate hypersensitivity responses. The data provide no support for a protective effect of viral infections against asthma in this population.

Cytokine levels in patients with Epstein-Barr virus associated laryngeal carcinoma

OBJECTIVE

Some researchers have suggested that Epstein-Barr virus may play a role in the pathogenesis of laryngeal malignancies. In order to clarify the role of cytokines in this disease context, the current study aimed to determine the serum levels of cytokines in Epstein-Barr virus DNA positive patients with laryngeal carcinoma.

SUBJECTS

The study included 10 patients with diagnosed laryngeal carcinoma and Epstein-Barr virus DNA positive tumour tissue samples. The control group comprised 10 Epstein-Barr virus DNA negative patients diagnosed with laryngeal carcinoma, 10 patients with acute Epstein-Barr virus infection and 10 healthy individuals.

METHOD

Serum cytokine levels were determined by enzyme-linked immunosorbent assay.

RESULTS

The Epstein-Barr virus DNA positive and negative laryngeal carcinoma patients showed no differences regarding serum levels of the following cytokines: interleukins 1beta, 2, 6 and 12, tumour necrosis factor alpha, and interferon gamma. However, serum levels of interleukin 10 and transforming growth factor beta1 were significantly higher in Epstein-Barr virus DNA positive laryngeal carcinoma patients compared with Epstein-Barr virus DNA negative laryngeal carcinoma patients (p < 0.05).

CONCLUSION

Our results suggest that the cytokines interleukin 10 and transforming growth factor beta1 may act as growth factors in Epstein-Barr virus related laryngeal carcinoma. These cytokines may thus represent potential targets for molecular therapeutic treatment for laryngeal carcinoma; they may also be useful as indicators of disease prognosis.

Early-life EBV infection protects against persistent IgE sensitization

BACKGROUND

Infection with EBV has previously been implicated in influencing allergic disorders, but its precise role remains contradictory. The timing of primary infection may contribute to the discrepancies.

OBJECTIVE

This study aimed at investigating whether the time-point of primary EBV infection during childhood could be of importance in modulating the risk of developing IgE sensitization.

METHODS

A total of 219 Swedish infants were followed prospectively to 5 years of age with clinical examinations, skin prick testing, specific IgE analyses, and determination of serostatus against EBV.

RESULTS

After analysis of the children's EBV serostatus, we found that 5-year-olds who were infected with EBV before the age of 2 years were at a significantly lower risk of being persistently IgE-sensitized-that is, sensitized at both 2 and 5 years of age (adjusted odds ratio, 0.34; 95% CI, 0.12-0.94). In contrast, contraction of EBV after 2 years of age was highly associated with late-onset IgE sensitization (adjusted odds ratio, 4.64; 95% CI, 1.57-13.69). Persistently sensitized 5-year-olds had higher specific-IgE levels than children with late-onset IgE sensitization (P < .01).

CONCLUSION

Our data support the value of early-life microbial exposure for protection against the development of IgE sensitization and underscore the proximate postnatal years as an important period during which EBV could contribute to an allergo-protective immune profile.

Herpesvirus seropositivity in childhood associates with decreased monocyte-induced NK cell IFN-gamma production

EBV infection is inversely associated with IgE sensitization in children, and this association is further enhanced by CMV coinfection. In mice, herpesvirus latency causes systemic innate activation and protection from bacterial coinfection, implying the importance of herpesviruses in skewing immune responses during latent infection. Early control of viral infections depends on IFN-gamma release by NK cells, which generally requires the presence of accessory cells. We investigated IFN-gamma production by NK cells in PBMCs from children seropositive (SP) for EBV alone, for both EBV and CMV, or seronegative for both viruses. The ability of classical (CD14(++)CD16(-)) and proinflammatory (CD14(+)CD16(+)) monocytes to induce autologous NK cell IFN-gamma was studied by coculture experiments with enriched CD3(-)CD56(+) cells. Transwell experiments were used to evaluate how monocytes interact with NK cells to induce IFN-gamma synthesis. SP children had a significantly reduced proportion of IFN-gamma(+) NK cells and cognate intracellular IFN-gamma levels, which was more pronounced in CMV-coinfected subjects. Also, resting PBMCs of SP children displayed lower proportions of proinflammatory monocytes. IFN-gamma production by NK cells was dependent on interactions with monocytes, with the proinflammatory subset inducing the highest IFN-gamma. Finally, SP children had markedly lower levels of plasma IFN-gamma, concurrent with in vitro findings. Herpesvirus infections could be one contributing factor for maturation toward balanced Th1-Th2 responses. Our data indicate that early infection by herpesviruses may affect NK cell and monocyte interactions and thereby also influence the development of allergies.