Low doses of IgG from atopic individuals can modulate in vitro IFN-γ production by human intra-thymic TCD4 and TCD8 cells: An IVIg comparative approach

IgG from Dermatophagoides pteronyssinus (Der p)-atopic individuals modulates non-atopic thymic B cell phenotype (alfa-4/beta-7) and cytokine production (IFN-γ, IL-9, and IL-10) with direct membrane interaction

Studies about thymic B cells are scarce in the literature, but it was suggested that they can exert modulatory and regulatory functions on the immune system. Thymic B cells can play some role in regulating the most frequent allergic background worldwide, the atopy induced by the mite Dermatophagoides pteronyssinus (Der p). Here, we aimed to evaluate if the polyclonal IgG repertoire produced by Der p-atopic individuals can influence the homing and cytokine profile of human thymic B derived from non-atopic children aged less than seven days. With this purpose, we produced polyclonal IgG formulations and cultivated human thymocytes in their presence. We also assessed IgG subclasses and the direct interaction of IgG with thymic B cell membranes. Our results could demonstrate that Der p-atopic IgG could not reduce the expression of α4β7 homing molecule as observed in response to the other IgG formulations and could reduce the frequency of IFN-γ- and IL-9-producing thymic B cells compared to the mock condition. Der p-atopic IgG could also induce thymic IL-10-producing B cells compared to control conditions. The IgG derived from Der p-atopic individuals failed to diminish the population of IL-13-producing thymic B cells, unlike the reduction observed with other IgG formulations when compared to the mock condition. All IgG formulations had similar levels of IgG subclasses and directly interacted with thymic B cell membranes. Finally, we performed experiments using peripheral non-atopic B cells where IgG effects were not observed. In conclusion, our observation demonstrates that IgG induced in allergic individuals can modulate non-atopic thymic B cells, potentially generating thymic B cells prone to allergy development, which seems to not occur in mature B cells.

Immune modulation and possible pathological implications mediated by naturally produced immunoglobulin G idiotypes: from historical to recent experimental and clinical studies focused on atopic dermatitis

Since the 1950s decade, it has been suggested that a naturally produced or induced repertoire of immunoglobulin G (IgG) idiotypes may exert some immunoregulatory functions. In the last decades, some more advanced theories have suggested that the repertoire of IgG idiotypes may influence the development or control of some atopic diseases. In atopic dermatitis (AD), some evidence indicated that the IgG repertoire obtained from these patients could effectively mediate regulatory functions on thymic and peripheral CD4+ and CD8+ T cells. Furthermore, some recent clinical trials have corroborated the hypothesis that IgG from AD patients can exert regulatory functions in vivo. Here, we revised some historical aspects that yield current approaches developed in vitro and in vivo to elucidate a recently proposed theory termed "hooks without bait" that can strengthen the broad spectrum of research about evaluating different sets of IgG idiotypes and determine their immunological effects.

IgG from patients with mild or severe COVID‑19 reduces the frequency and modulates the function of peripheral mucosal-associated invariant T cells in PBMCs from healthy individuals

Lower levels of peripheral mucosal-associated invariant T (MAIT) cells have been observed in the peripheral blood of patients with severe coronavirus disease 2019 (COVID-19). Following on from previous research into the effect of the IgG repertoire on human lymphocytes, the present study aimed to evaluate if immunoglobulin G (IgG) antibodies obtained from patients with mild or severe COVID-19 contribute to these effects on MAIT cells. Culture experiments were performed using healthy human peripheral blood mononuclear cells (PBMCs) and different repertoires of IgG obtained from patients with COVID-19 as a mild or severe disease and compared with mock, healthy control or therapeutic IgG conditions. The results indicate that the IgG repertoire induced during the development of mild and severe COVID-19 has, per se, the in vitro potential to reduce the frequency of MAIT cells and the production of IFN-γ by the MAIT cell population in PBMCs from healthy individuals. In conclusion, the results of the present study indicate that IgG in patients with severe COVID-19 may participate in the reduction of peripheral MAIT cell frequency and hinder the antiviral activity of these cells.

Differential modulation of IL-4, IL-10, IL-17, and IFN-γ production mediated by IgG from Human T-lymphotropic virus-1 (HTLV-1) infected patients on healthy peripheral T (CD4+, CD8+, and γδ) and B cells

Human T-lymphotropic virus 1 (HTLV-1) infected individuals remain as asymptomatic carriers (ACs) or can develop the chronic neurological disorder HTLV-1-associated myelopathy/Tropical Spastic Paraparesis (HAM/TSP) or the adult T-cell leukemia/lymphoma (ATLL), and the immunological mechanisms involved in this pathologies need to be elucidated. Recently, it has been demonstrated that induced or naturally developed IgG repertoires obtained from different groups of donors, grouped by immune status, can modulate human T and B cell functions. Here we aimed to evaluate if the IgG obtained from HTLV-1-infected ACs, HAM/TSP, and ATLL patients can differentially modulate the production of cytokines by human T and B cells. With this purpose, we cultured PBMCs with IgG purified from ACs, HAM/TSP, or ATLL donors and evaluated the frequency and intracellular cytokine production by flow cytometry. Our results indicate that IgG from HAM/TSP patients could induce an augment of IL-17-producing CD4+ T cells, reduce the frequency of IL-4-producing CD4+ T cells, increase IFN-γ-producing CD8+ T cells, and reduce IL-4-producing CD8+ T cells. IgG from ATLL could reduce the frequency of IL-4-producing CD4+ T cells, similarly to IgG from HAM/TSP /TSP, and could reduce the frequency of IFN-γ-producing γδT cells without influence on IL-17- and IL4-producing γδT and could reduce the frequency of IL-10- producing B cells. Finally, IgG from both HAM/TSP and ATLL patients could reduce the frequency of IFN-γ producing B cells. In conclusion, these results suggest that these preparations are active, partly overlapping in their effects, and able to elicit distinct effects on target populations.

IgG from Adult Atopic Dermatitis (AD) Patients Induces Nonatopic Neonatal Thymic Gamma-Delta T Cells (γδT) to Acquire IL-22/IL-17 Secretion Profile with Skin-Homing Properties and Epigenetic Implications Mediated by miRNA

γδT cells mature in the human thymus, and mainly produce IL-17A or IFN-γ, but can also produce IL-22 and modulate a variety of immune responses. Here, we aimed to evaluate whether IgG from AD patients (AD IgG) can functionally modulate thymic nonatopic γδT cells. Thymic tissues were obtained from 12 infants who had not had an atopic history. Thymocytes were cultured in mock condition, or in the presence of either AD IgG or therapeutic intravenous IgG (IVIg). Following these treatments, intracellular cytokine production, phenotype, and microRNA expression profiles were investigated. AD IgG could downregulate α4β7, upregulate CLA, and induce the production of IFN-γ, IL-17, and IL-22 in γδT cells. Although both AD IgG and IVIg could directly interact with γδT cell membranes, AD IgG could reduce γδT cell apoptosis. AD IgG could upregulate nine miRNAs compared to IVIg, and six when compared to the mock condition. In parallel, some miRNAs were downregulated. Target gene prediction and functional analysis indicated that some target genes were enriched in the negative regulation of cellular transcription. This study shows that AD IgG influences the production of IL-17 and IL-22 by intrathymic nonatopic γδT cells, and demonstrates epigenetic implications mediated by miRNAs.

IgG from Adult Atopic Dermatitis (AD) Patients Induces Thymic IL-22 Production and CLA Expression on CD4+ T Cells: Possible Epigenetic Implications Mediated by miRNA

Atopic dermatitis (AD) is a common relapsing inflammatory skin disorder characterized by immune-mediated inflammation and epidermal barrier dysfunction. The pathogenesis of AD is multifactorial and has not been fully elucidated to date. This study aimed to evaluate whether serum IgG from adult AD patients could modulate the thymic maturation of IL-22-producing T cells and CLA+ T cells of non-atopic infants. Given that miRNAs regulate immune response genes, we evaluated whether miRNA expression is also altered in cultured thymocytes. Thymocytes were cultured with purified IgG from AD patients or control conditions (mock, Intravenous-IgG (IVIg), non-atopic IgG, or atopic non-AD IgG). Using flow cytometry analysis, we assessed the expression of CLA and intracellular levels of IL-4, IFN-γ, and IL-22 on double-positive T cells (DP T), CD4 T cells, or CD8 T cells. We also investigated the frequency of IgG isotypes and their direct interaction with the thymic T cells membrane. The miRNA profiles were evaluated by the Illumina small RNA-seq approach. MiRNA target gene prediction and enrichment analyses were performed using bioinformatics. Increased frequencies of IL-22 and CLA+ producing CD4+ T cells cultured with IgG of AD patients was seen in non-atopic infant thymocytes compared to all control conditions. No alterations were observed in the frequency of IgG isotypes among evaluated IgG pools. Evidence for a direct interaction between IgG and thymic DP T, CD4 T, and CD8 T cells is presented. The small RNA-seq analysis identified ten mature miRNAs that were modulated by AD IgG compared to mock condition (miR-181b-5p, hsa-miR-130b-3p, hsa-miR-26a-5p, hsa-miR-4497, has-miR-146a, hsa-let-7i-5p, hsa-miR-342-3p, has-miR-148a-3p, has-miR-92a and has-miR-4492). The prediction of the targetome of the seven dysregulated miRNAs between AD and mock control revealed 122 putative targets, and functional and pathway enrichment analyses were performed. Our results enhance our understanding of the mechanism by which IgG can collaborate in thymic T cells in the setting of infant AD.

Non-atopic Neonatal Thymic Innate Lymphoid Cell Subsets (ILC1, ILC2, and ILC3) Identification and the Modulatory Effect of IgG From Dermatophagoides Pteronyssinus (Derp)-Atopic Individuals

Innate lymphoid cells (ILCs) are classified into distinct subsets termed ILC1, ILC2, and ILC3 cells. The existing literature lacks evidence identifying ILCs and their subsets in the human thymus but already demonstrates that they can exert several functions in regulating immune responses. Furthermore, it was already described that IgG's repertoires could modulate lymphocytes' maturation in the human thymus. Here we aimed to identify ILCs subsets in the human thymus and provide insight into the possible modulatory effect of purified IgG on these cells. Thymic tissues were obtained from 12 infants without an allergic background (non-atopic), and a literature-based peripheral ILCs staining protocol was used. Purified IgG was obtained from non-atopic individuals (n-At), atopic individuals reactive to allergens non-related to dust mites (nr-At), and atopic individuals reactive to the mite Dermatophagoides pteronyssinus (Derp-At). As with all tissues in which they have already been detected, thymic ILCs are rare, but we could detect viable ILCs in all tested tissues, which did not occur with the ILC1 subset. ILC2 and ILC3 NKp44+ subsets could be detected in all evaluated thymus, but ILC3 NKp44- subset could not. Next, we observed that Derp-At IgG could induce the expression of ILC2 phenotype, higher levels of IL-13, and lower levels of IL-4 when compared to IgG purified from non-atopic or non-related atopic (atopic to allergens excluding dust mites) individuals. These results contribute to the elucidation of human thymic ILCs and corroborate emerging evidence about IgG's premature effect on allergy development-related human lymphocytes' modulation.

Preconceptional Immunization Can Modulate Offspring Intrathymic IL-17-Producing γδT Cells with Epigenetic Implications Mediated by microRNAs

The mechanisms through which maternal immunization can modulate offspring thymic maturation of lymphocytes are not fully understood. Here, we aimed to evaluate whether maternal OVA-immunization can inhibit the maturation of IL-17-producing γδT cells in offspring thymus, and if this mechanism has epigenetic implications mediated by microRNAs (miRNAs) expression. Wild-type (WT) C57BL/6 females were immunized with OVA in Alum or Alum alone and were mated with normal WT males. Evaluating their offspring thymus at 3 or 20 days old (d.o.), we observed that maternal OVA immunization could inhibit the thymic frequency of offspring CD27- and IL-17+ γδT cells at the neonatal and until 20 days old. Furthermore, we evaluated the expression of function-related γ and δ variable γδTCR chains (Vγ1, Vγ2, Vγ3, Vδ4, and Vδ6.3), observing that maternal OVA-immunization inhibits Vγ2 chains expression. The small RNAs (sRNAs), particularly miRNAs, and messenger RNAs (mRNA) expression profiles by pools of thymus tissue samples (from 9 to 11 mice) from offspring OVA-immunized or Alum-immunized mothers were analyzed via Illumina sequencing platform and bioinformatics approaches. Using a fold change >4, our results showed that seven miRNAs (mmu-miR-126a-3p, 101a-3p, 744-3p,142-5p, 15a-5p, 532-5p, and 98-5p) were differentially expressed between both groups. Ten target genes were predicted to interact with the seven selected miRNAs. There were no enriched categories of gene ontology functional annotation and pathway enrichment analysis for the target genes. Interestingly, four of the identified miRNAs (mmu-miR-15a, mmu-miR-101 mmu-miR-126, and mmu-miR-142) are related to IL-17 production. Our data is of significance because we demonstrate that maternal immunization can modulate offspring thymic maturation of IL-17-producing γδT cells possibly by an epigenetic mechanism mediated by miRNAs.

The Potential of IgG to Induce Murine and Human Thymic Maturation of IL-10+ B Cells (B10) Revealed in a Pilot Study

Regulatory B (B10) cells can control several inflammatory diseases, including allergies; however, the origin of peripheral B10 cells is not fully understood, and the involvement of primary lymphoid organs (PLOs) as a primary site of maturation is not known. Here, using a murine model of allergy inhibition mediated by maternal immunization with ovalbumin (OVA), we aimed to evaluate whether B10 cells can mature in the thymus and whether IgG can mediate this process. Female mice were immunized with OVA, and offspring thymus, bone marrow, spleen, lung, and serum samples were evaluated at different times and after passive transfer of purified IgG or thymocytes. A translational approach was implemented using human nonatopic thymus samples, nonatopic peripheral blood mononuclear cells (PBMCs), and IgG from atopic or nonatopic individuals. Based on the expression of CD1d on B cells during maturation stages, we suggest that B10 cells can also mature in the murine thymus. Murine thymic B10 cells can be induced in vitro and in vivo by IgG and be detected in the spleen and lungs in response to an allergen challenge. Like IgG from atopic individuals, human IgG from nonatopic individuals can induce B10 cells in the infant thymus and adult PBMCs. Our observations suggest that B10 cells may mature in the thymus and that this mechanism may be mediated by IgG in both humans and mice. These observations may support the future development of IgG-based immunoregulatory therapeutic strategies.

Natural Self-Ligand Gamma Delta T Cell Receptors (γδTCRs) Insight: The Potential of Induced IgG

A γδ T cell acquires functional properties in response to the gamma delta T cell receptor γδTCR signal strength during its development in the thymus. The elucidation of the potential ligands of γδ T cell receptors are of extreme importance; however, they are still not understood. Here we revise the actual state of the art of candidates to exert the function of γδTCR ligands, and propose a theoretical contribution about new potential ligands of γδTCRs, based on biological and hypothetical pieces of evidence in the literature. In conclusion, we hypothetically suggest a possible role of induced antibodies according to the individual’s immune status, mainly of the IgG subclass, acting as γδTCR ligands. Considering that IgG production is involved in some essential immunotherapy protocols, and almost all vaccination protocols, our discussion opens a new and broad field to further exploration.

Do different IgG repertoires play a role in B- and T-cell functional modulation during ontogeny? The "hooks without bait" theory

The mechanisms by which immunoglobulin (Ig)G can modulate immunity have been investigated over the past few decades. In the past three years, some studies have demonstrated that IgG can play a pivotal role in mediating complex interactions that result in functional lymphocyte modulation during maturation in self or offspring primary lymphoid organs. This effect appears to be dependent on the IgG repertoire in the absence of the influence of antigens and the functionality of diverse cell populations, including B, αβT (CD4 T and CD8 T), invariant natural killer T and γδT cells, in mice and humans. Based on the literature, especially on findings resulting from the therapeutic use of purified IgG (intravenous Ig) and recent pieces of evidence obtained by my group, the "hooks without bait" theory is described here to guide the future development of therapies for specific immune regulation.

IgG from atopic dermatitis patients induces non-atopic infant thymic invariant natural killer T (iNKT) cells to produce IL-4, IL-17, and IL-10

BACKGROUND

Atopic dermatitis (AD) pathogenesis still needs to be elucidated, but invariant natural killer T (iNKT) cell involvement was already described by several groups. Our group has demonstrated that IgG antibodies purified from AD patients can modulate cytokine production by thymic T cells. Here we aimed to investigate if IgG from AD patients can modulate infant non-atopic thymic iNKT cells cytokine production in order to collaborate with the elucidation of AD development in infancy.

METHODS

Thymic tissues were obtained from children from non-atopic mothers, and IgG was purified from AD patients diagnosed as moderate or severe and, as controls, from subjects clinically classified as non-atopic individuals. PBMCs from non-atopic individuals were also used in this study.

RESULTS

Our results demonstrated that IgG from AD patients could induce non-atopic children thymic iNKT cells to produce higher levels of intracellular IL-4, IL-10, and IL-17 when compared to all control conditions. No effect was observed in non-atopic adults peripheral iNKT. We also observed that IgG from AD patients induces an increase in the expression of CD4 and Rorγt transcription factor in non-atopic children thymic iNKT cells compared to the condition of all controls.

CONCLUSIONS

These observations suggest that IgG from AD patients can induce a cytokine profile by thymic iNKT cells from non-atopic infants compatible with the observations in AD development, which can collaborate with the elucidation of AD pathogenesis.

IgG from Non-atopic Individuals Induces In Vitro IFN-γ and IL-10 Production by Human Intra-thymic γδT Cells: A Comparison with Atopic IgG and IVIg

Matured in the thymus, γδT cells can modulate the development of allergy in humans. The main γδT cell subsets have been described as interleukin (IL)-17A or interferon (IFN)-γ producers, but these cells can also produce other modulatory cytokines, such as IL-4 and IL-10. Here, we aimed to evaluate whether IgG can modulate the profile of cytokine production by γδT cells during their maturation in the thymus and after its migration to peripheral tissues. Thymic tissues were obtained from 12 infants, and peripheral blood mononuclear cells (PBMCs) were obtained from adults (both groups without an atopic background). IgG was purified from atopic and non-atopic volunteers. Thymocytes and PBMCs were cultured with purified atopic or non-atopic IgG, and intracellular cytokine production and phenotype were assessed. Mock and IVIg conditions were used as controls. IgG from non-atopic individuals induced IFN-γ and IL-10 production by thymic γδT cells, and no effect was observed on peripheral γδT cells. IL-17 production was inhibited by non-atopic IgG on thymic γδT cells and augmented by atopic IgG on peripheral γδT cells. Modulated thymic γδT cells did not produce IFN-γ and IL-10 simultaneously. We additionally evaluated the phenotype of intrathymic γδT cells and observed that IgG from all groups could induce CD25 expression and could not influence the CD28 expression of these cells. This report describes evidence revealing that IgG may influence the production of IFN-γ and IL-10 by intrathymic γδT cells depending on the donor atopic state. This observation is unprecedented and needs to be considered in further studies in the IgG immunotherapy field.

Preconception immunization can modulate intracellular Th2 cytokine profile in offspring: in vivo influence of interleukin 10 and B/T cell collaboration

Introduction

In the last few years our group has been studying the mechanisms involved in the inhibition of allergy in offspring mediated by preconception maternal immunization, but these mechanisms are not fully understood. Such mechanisms that we have studied aimed at the passive transfer of maternal antibodies and its influence on offspring immune status.

Aim of the study

To evaluate whether maternal immunization could modulate intracellular Th1/Th2 profiles in offspring.

Material and methods

C57BL/6 female wild type mice (WT), interleukin (IL)-10^-/- or CD28^-/- mice were immunized or not with ovalbumin (OVA) and were mated with respective lineage males and offspring were evaluated at 3 days old (d.o.), 20 d.o., or 20 d.o. after neonatal immunization.

Results

Preconception OVA immunization induced a marked reduction in IL-4 secretion by TCD4+ cells of WT offspring when compared with offspring from non-immunized mothers. The maternal immunization of IL-10^-/- mice induced an increase in the TCD4+IL-4+ percentage in offspring and a reduction in TCD4+IFN-γ+ cells. The maternal immunization in CD28^-/- mice induced augment IL-4 intensity in 3 and 20 d.o. offspring TCD4+ cells.

Conclusions

Our results reveal that maternal immunization with OVA can down-regulate the Th2 pattern in offspring and this regulation is dependent on IL-10 and B/T cell collaboration.

Maternal immunization downregulates offspring TCD4 regulatory cells (Tregs) thymic maturation without implications for allergy inhibition

The regulation of offspring allergy development mediated by maternal immunization was evidenced by several groups, and this mechanism seems to involve the induction of regulatory T cells (Tregs) on offspring. Here, we aimed to evaluate whether the effect of maternal immunization on offspring Tregs occurs as a result of peripheral or central modulation. Briefly, C57BL/6 female mice were immunized with OVA in Alum or Alum alone and boosted with OVA in saline or saline only after 10 and 20 days. Non-immunized offspring serum, thymus and spleen were evaluated at 3 or 20 days old, and some groups of pups were submitted to neonatal OVA-immunization protocol for the subsequent evaluation of antibody production and allergic response. Our experimental protocol could be validated because maternal OVA-immunization inhibited offspring allergic response as evidenced by the suppression of offspring IgE production and allergic lung inflammation. Interestingly, maternal immunization reduced the frequency of offspring thymic Tregs with an opposite effect on spleen Tregs. Furthermore, after neonatal immunization, the frequency of lung-infiltrated Tregs was also augmented on offspring from immunized mothers. In conclusion, maternal OVA-immunization can inhibit the thymic maturation of offspring Tregs without implications on peripheral Tregs induction and allergy inhibition.

Preconceptional allergen immunization can induce offspring IL-17 secreting B cells (B17): do they share similarities with regulatory B10 cells?

BACKGROUND

IL-17-producing B cells can be identified in both mice and human and were named B17 cells. The role of B17 cells still needs to be elucidated and its inflammatory or regulatory functions remain controversial.

OBJECTIVE

We evaluate the effect of maternal immunization with OVA on offspring B cells that produces IL-17 and can show a regulatory potential by IL-10 production.

METHODS

C57BL/6 WT, IL-10^-/- or CD28^-/- female mice were immunized or not with OVA in Alum, and immunized females were boosted after 10 and 20 days. Immunized and non-immunized females were mated, and pups from both groups were evaluated at 3 or 20 days old (d.o.). Some offspring from the aforementioned two groups were immunized with OVA at 3 d.o., boosted after 10 days and evaluated at 20 d.o.

RESULTS

Maternal immunization with OVA induced offspring B cells to produce IL-17 at higher intensity compared to the control group of offspring at 3 d.o. This effect was maintained until 20 d.o. and even after neonatal immunization with OVA. The co-production of IL-10 on offspring IL-17+B cells is up-regulated in response to maternal immunization with OVA. Maternal immunization with OVA on IL-10^-/- mice reveals reduced percentage and mean of fluorescence intensity of IL-17 on B cells of offspring.

CONCLUSION

Preconception OVA immunization can induce offspring B cells that produce IL-17 at higher intensity and co-produce mainly IL-10. This could be the reason why B17 cells had been described in the literature with controversial roles upon their regulatory function.

IgG from atopic dermatitis patients induces IL-17 and IL-10 production in infant intrathymic TCD4 and TCD8 cells

INTRODUCTION

Our group recently demonstrated that IgG modulates αβT cell cytokine production during the maturation process in the human thymus. The effects of this modulation are IgG repertoire dependent and can exert a systemic and long-term impact.

OBJECTIVE

To investigate whether IgG from atopic dermatitis (AD) patients can modulate cytokine production of infant intrathymic TCD4 and TCD8 cells in vitro.

METHODS

Thymic tissues were obtained from newborn children from nonatopic mothers, and thymocytes were cultured for 6 days with purified IgG from AD patients or with intravenous immunoglobulin (IVIG) or mock conditions as controls. Cells were gated as double positive T cells (TDP^- CD4⁺ CD8⁺ ), TCD4 cells (CD4⁺ CD8^- ), or TCD8 cells (CD4^- CD8⁺ ), and intracellular levels of IL-17A, IFN-γ, TNF-α, IL-4, IL-10, and TGF-β were evaluated by flow cytometry.

RESULTS

Compared to mock and IVIG culture conditions, IgG of AD individuals induced in vitro intracellular production of IL-17 and IL-10 by intrathymic TDP, TCD4, and TCD8 cells of infants. TGF-β was also detected at a higher frequency in response to AD IgG in TDP and TCD8 cells compared to mock and IVIG cultured conditions. An opposite effect was detected upon IFN-γ production in TCD4 cells, such that AD IgG reduced IFN-γ production compared to production under mock conditions but not under IVIG conditions.

CONCLUSION

IgG of AD patients can stimulate cytokine production in infant thymocytes and thus resembles the peripheral profile observed in adults. These findings suggest a novel mechanism that can contribute to AD pathogenesis.