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Donata Vercelli

Publications and source records attributed to Donata Vercelli.

At least 19 recordsLinked to original sources
PubMed2006

Th2 cell-selective enhancement of human IL13 transcription by IL13-1112C>T, a polymorphism associated with allergic inflammation.

IL-13 is a central mediator of allergic inflammation. The single nucleotide polymorphism IL13-1112C>T (rs1800925) is associated with allergic phenotypes in ethnically distinct populations, but the underlying mechanism(s) remain unknown. Using in vivo, in vitro, and in silico analysis, we show that the IL13-1112T allele enhanced IL13 promoter activity in primary human and murine CD4(+) Th2 lymphocytes. Increased expression of IL13-1112T in Th2 cells was associated with the creation of a Yin-Yang 1 binding site that overlapped a STAT motif involved in negative regulation of IL13 expression and attenuated STAT6-mediated transcriptional repression. Because IL-13 secretion was increased in IL13-1112TT homozygotes, we propose that increased expression of IL13-1112T in vivo may underlie its association with susceptibility to allergic inflammation. Interestingly, IL13-1112T had opposite transcriptional effects in nonpolarized CD4(+) T cells, paralleled by distinct patterns of DNA-protein interactions at the IL13 promoter. Our findings suggest the nuclear milieu dictates the functional outcome of genetic variation.

Animals↗
PubMed2006

Functional dissection identifies a conserved noncoding sequence-1 core that mediates IL13 and IL4 transcriptional enhancement.

Conserved noncoding sequence (CNS)-1 has been shown to coordinately regulate the expression of the Th2 cytokine genes IL4, IL13, and IL5. We have used the interaction between CNS-1 and the human IL13 and IL4 promoters as a model to pursue the molecular mechanisms underlying CNS-1-dependent regulation of Th2 cytokine gene transcription. CNS-1 potently enhanced the activity of IL13 and IL4 promoter reporter vectors upon full T cell activation. Analysis of CNS-1 deletion mutants mapped enhancer activity to a short core (CNS-1-(270-337)) that contains three closely spaced cyclic AMP-responsive elements (CRE). CRE site 2 bound CRE-binding protein (CREB) and activating transcription factor (ATF)-2 in vitro and was essential for CNS-1-dependent up-regulation of IL13 transcription. Cotransfection of an IL13 reporter construct with expression vectors for wild type or mutant CREB and ATF-2 showed that CREB, but not ATF-2, regulates CNS-1 enhancer activity. Notably, chromatin immunoprecipitation analysis showed T cell activation recruits CREB and the coactivator CREB-binding protein (CBP)/p300 to the endogenous CNS-1. Moreover, CBP/p300 activity was essential for CNS-1-mediated enhancement of IL13 transcription. Collectively, these data define the region within CNS-1 responsible for enhancement of IL13 and IL4 transcription and suggest CREB/CBP-dependent mechanisms play an important role in facilitating Th2 cytokine gene expression in response to T cell receptor signaling.

Animals↗
PubMed2006

Exposure to a farming environment has allergen-specific protective effects on TH2-dependent isotype switching in response to common inhalants.

BACKGROUND: IgE synthesis by human B cells results from allergen-dependent, T(H)2-mediated isotype switching. Exposure to a farming environment protects against IgE responses. OBJECTIVE: We reconstructed allergen-dependent switching patterns in vivo to identify the level or levels at which farm exposure acts to protect against atopy. METHODS: Serum IgG1 to IgG4 and IgE to grass (rPhl p 1 and rPhl p 5), cat (rFel d 1), and mite (rDer p 2) were assessed by means of ELISA in the Allergy and Endotoxin study population (812 children). Farm exposure was defined as currently living on a farm, exposure to stables/farm milk in the first year of life, or both. RESULTS: Farm exposure did not affect allergen-specific IgG2 and IgG3 levels but had complex allergen-specific effects on IgG1, IgG4, and IgE levels. Exposure protected against grass-specific responses at every step along the IgG1/IgG4/IgE switching pathway but had no significant effect on mite responses. Protection from cat responses was concentrated at the IgG1 level. For all allergens, failure to express IgG1 was associated with low prevalence of IgG4 or IgE responses. Notably, coexpression of IgG1, IgG4, and IgE to grass was associated with increased risk of allergic disease and higher IgE levels compared with production of IgG1 and IgE without IgG4, suggesting IgG4 coexpression marks stronger activation of T(H)2-dependent events. CONCLUSION: The protective effects of farm exposure were confined to T(H)2-dependent IgG1, IgG4, and IgE expression and were allergen and switch stage specific, suggesting that distinct mechanisms regulate individual steps within allergen-induced class switching in vivo. CLINICAL IMPLICATIONS: Environmental interventions to prevent IgE expression might need to be tailored to specific allergens.

Agriculture↗
PubMed2006

The human IL-13 locus in neonatal CD4+ T cells is refractory to the acquisition of a repressive chromatin architecture.

The Th2 cytokine IL-13 is a major effector molecule in human allergic inflammation. Notably, IL-13 expression at birth correlates with subsequent susceptibility to atopic disease. In order to characterize the chromatin-based mechanisms that regulate IL-13 expression in human neonatal CD4(+) T cells, we analyzed patterns of DNase I hypersensitivity and epigenetic modifications within the IL-13 locus in cord blood CD4(+) T cells, naive or differentiated in vitro under Th1- or Th2-polarizing conditions. In naive CD4(+) T cells, hypersensitivity associated with DNA hypomethylation was limited to the distal promoter. Unexpectedly, during both Th1 and Th2 differentiation, the locus was extensively remodeled, as revealed by the formation of numerous HS sites and decreased DNA methylation. Obvious differences in chromatin architecture were limited to the proximal promoter, where strong hypersensitivity, hypomethylation, and permissive histone modifications were found selectively in Th2 cells. In addition to revealing the locations of putative cis-regulatory elements that may be required to control IL-13 expression in neonatal CD4(+) T cells, our results suggest that differential IL-13 expression may depend on the acquisition of a permissive chromatin architecture at the proximal promoter in Th2 cells rather than the formation of locus-wide repressive chromatin in Th1 cells.

CD4-Positive T-Lymphocytes↗
PubMed2006

Mechanisms of the hygiene hypothesis--molecular and otherwise.

The hygiene hypothesis was initially formulated to explain the steep increase in the prevalence of allergies in Western societies observed over the past few decades. It proposes that the microbial environment interfaces with the innate immune system and modulates its ability to impart instructions to adaptive immune responses, particularly when such interactions occur in utero and/or in early life. Recent research on the molecular mechanisms of the hygiene hypothesis highlights the role of Toll-like receptor ligands in modulating allergic inflammation and the importance of bacterial products in directing the development of the host's immune system. Genetic analysis, by contrast, clearly shows that the response threshold of the immune system to environmental stimuli is controlled by natural genetic variation and gene-environment interactions, suggesting that the complex interplay between the organism and the environment might not be regulated by a single mechanism.

Animals↗
PubMed2005

IL-21 effects on human IgE production in response to IL-4 or IL-13.

In human atopic disease, IgE sensitizes the allergic response, while IgG4 is protective. Because IL-4 and IL-13 trigger switch recombination to both IgE and IgG4, additional agents must regulate the balance between these isotypes to influence susceptibility or tolerance to atopy. In this report, we define in vitro conditions leading to activation or inhibition of human IgE and IgG4 production by IL-21. IL-21 reduced IL-4-driven IgE synthesis by mitogen-stimulated human PBMC. IL-21 inhibition of human IgE production was not a direct effect on B cells, was not seen following B cell activation with IL-13, and was overcome by CD40 ligation. Neither IFN-gamma, IL-10, IL-12, CD40L expression, nor apoptosis was responsible for the inhibitory effect. In contrast, IL-21-stimulated secretion of IgG4 from PBMC. Our findings indicate that IL-21 may influence the production of both human IgE and IgG4, and thus contribute to the regulation of atopic reactions.

Antibodies, Monoclonal↗
PubMed2005

Association of defensin beta-1 gene polymorphisms with asthma.

BACKGROUND: Defensins are antimicrobial peptides that may take part in airway inflammation and hyperresponsiveness. OBJECTIVE: We characterized the genetic diversity in the defensin beta-1 (DEFB1) locus and tested for an association between common genetic variants and asthma diagnosis. METHODS: To identify single nucleotide polymorphisms (SNPs), we resequenced this gene in 23 self-defined European Americans and 24 African Americans. To test whether DEFB1 genetic variants are associated with asthma, we genotyped 4 haplotype-tag SNPs in 517 asthmatic and 519 control samples from the Nurses' Health Study (NHS) and performed a case-control association analysis. To replicate these findings, we evaluated the DEFB1 polymorphisms in a second cohort from the Childhood Asthma Management Program. RESULTS: Within the NHS, single SNP testing suggested an association between asthma diagnosis and a 5' genomic SNP (g.-1816 T>C; P = .025) and intronic SNP (IVS+692 G>A; P = .054). A significant association between haplotype (Adenine, Cytosine, Thymine, Adenine [ACTA]) and asthma ( P = .024) was also identified. Associations between asthma diagnosis and both DEFB1 polymorphisms were observed in Childhood Asthma Management Program, a second cohort: g.-1816 T>C and IVS+692 G>A demonstrated significant transmission distortion ( P = .05 and .007, respectively). Transmission distortion was not observed in male subjects. The rare alleles (-1816C and +692A) were undertransmitted to offspring with asthma, suggesting a protective effect, contrary to the findings in the NHS cohort. Similar effects were evident at the haplotype level: ACTA was undertransmitted ( P = .04) and was more prominent in female subjects ( P = .007). CONCLUSION: Variation in DEFB1 contributes to asthma diagnosis, with apparent gender-specific effects.

Asthma↗
PubMed2005

Genetic regulation of IgE responses: Achilles and the tortoise.

In the last few decades, basic biology and immunology have thrived, largely thanks to the use of model organisms that allow exploration of complex functions in ideal experimental conditions and genetically defined backgrounds. IgE regulation studies are no exception to this rule. The current challenge is to anchor what we are learning in test tubes and animals to mechanisms of disease in patients with allergy. With information about the human genome rapidly piling up, and strong associations between single nucleotide polymorphisms and disease phenotypes reported more and more often, it is becoming clear that such anchoring cannot occur without a robust integration between the biology of model systems and the biology of natural genetic variants. Here we will argue that an essential component of this integration is the functional analysis of the mechanisms through which natural variation affects pathways relevant to the pathogenesis of IgE-dependent inflammation.

Animals↗
PubMed2005

IL-13 R130Q, a common variant associated with allergy and asthma, enhances effector mechanisms essential for human allergic inflammation.

Genetic factors are known to strongly influence susceptibility to allergic inflammation. The Th2 cytokine IL-13 is a central mediator of allergy and asthma, and common single-nucleotide polymorphisms in IL13 are associated with allergic phenotypes in several ethnically diverse populations. In particular, IL13+2044GA is expected to result in the nonconservative replacement of arginine 130 (R130) with glutamine (Q). We examined the impact of IL13+2044GA on the functional properties of IL-13 by directly comparing the activity of WT IL-13 and IL-13 R130Q on primary human cells involved in the effector mechanisms of allergic inflammation. Our results show that IL-13 R130Q was significantly more active than WT IL-13 in inducing STAT6 phosphorylation and CD23 expression in monocytes and hydrocortisone-dependent IgE switching in B cells. Notably, IL-13 R130Q was neutralized less effectively than WT IL-13 by an IL-13R2 decoy. Decreased neutralization of the minor variant could contribute to its enhanced in vivo activity. Neither IL-13 variant was able to engage T cells, which suggests that increased allergic inflammation in carriers of IL13+2044A depends on enhanced IL-13-mediated Th2 effector functions rather than increased Th2 differentiation. Collectively, our data indicate that natural variation in the coding region of IL13 may be an important genetic determinant of susceptibility to allergy.

Animals↗
PubMed2004

TOLL-like receptor 10 genetic variation is associated with asthma in two independent samples.

TOLL-like receptor 10 (TLR10) is the most recently identified human homolog of the Drosophila TOLL protein. In humans, the TOLL-like receptors recognize pathogen-associated molecular patterns (PAMPs) as part of innate immune host defenses. Localized to chromosome 4p14, the specific ligands and functions of TLR10 are currently unknown, although it is expressed in lung and in B-lymphocytes. TLR10 is a potential asthma candidate gene because early life innate immune responses to ubiquitous inhaled allergens and PAMPs may influence asthma susceptibility. Resequencing in 47 subjects revealed a total of 78 single nucleotide polymorphisms (SNPS) (1 SNP per 106 bp) of which only 11 had been previously published. A significant association (p < or = 0.02) between two SNPs (c.+1031G>A, c.+2322A>G) and physician-diagnosed asthma was observed in a case control study (517 cases, 519 control subjects) of European American subjects nested within the Nurses' Health Study cohort. The association for these same two SNPs (p < or = 0.015) replicated in an independent family based cohort, where a measure of airway hyperresponsiveness (PC20) was also associated (p = 0.026 for c.+1031G>A). Consistent association in two independent samples and association with an intermediate phenotype provides strong support for TLR10 genetic variation contributing to asthma risk.

Black or African American↗
PubMed2004

Genetics, epigenetics, and the environment: switching, buffering, releasing.

Increasing evidence suggests that the interactions between genes and environment might play a critical role in the pathogenesis of complex diseases, such as asthma, that exhibit a heritable component but do not follow Mendel's laws. Gene-environment interactions are extremely complex and not linear, such that the same genetic variants might be associated with opposite phenotypes in different environments. This is particularly evident for innate immunity genes, which operate at the interface between the immune system and the pathogen world. This article examines gene-environment interactions by using CD14 as a model and argues that the conflicting results of epidemiologic studies on CD14*C-159T result from differences in environmental conditions essential to modulate CD14 gene expression. Furthermore, on the basis of how rapidly environmental changes have affected the incidence of immune diseases, I argue that a full understanding of gene-environment interactions requires that epigenetic as well as classical genetic mechanisms be taken into account. Recent data about the effect of diet on gene methylation and the release of hidden genetic variation by impairment of heat shock protein 90-mediated buffering systems offer eloquent examples of how epigenetic mechanisms might affect gene-environment interactions.

DNA Methylation↗
PubMed2004

Rethinking Th2 antibody responses and allergic sensitization.

Human Th2 cytokines (interleukins 4 and 13) induce co-expression of IgE and IgG4 through sequential switching. The regulation of IgG4 responses and the role of these responses in the pathogenesis of allergy have not been characterized. We are addressing these issues by comparing and contrasting the expression of allergen-specific IgE and IgG4 in a population of European children thoroughly defined for lifestyle, environmental exposures and allergic phenotypes. The current analysis focused exclusively on children from non-farming families (n=493) in order to avoid potential effects of exposure to microbial products abundant in farming environments. We found that allergens induce Th2-mediated IgG4 and/or IgE responses in the majority of the population. Approximately two-thirds of the children had allergen-specific IgG4 but not IgE, only a minority had both IgG4 and IgE, only a few were negative for both, and virtually none had only IgE. The prevalence of asthma and hay fever was dramatically higher in children with high IgG4 and IgE compared to children who only mounted IgG4 or low IgG4 and IgE responses. These results appear to recapitulate different stages of in vivo Th2-dependent sequential switching from IgG4 to IgE. These patterns of Th2-induced antibody responses may warrant a redefinition of the notion of allergen sensitization.

Agriculture↗
PubMed2003

S epsilon S mu and S epsilon S gamma switch circles in human nasal mucosa following ex vivo allergen challenge: evidence for direct as well as sequential class switch recombination.

B cells switch to IgE under the influence of IL-4, IL-13, and CD40 costimulation through a multistep process involving epsilon germline transcription and class switch recombination. Classically, switching has been considered an event restricted to lymphoid tissues; however, epsilon germline transcripts (I(initiator)epsilon RNA) have been observed within lung, sinus, and nasal tissue of individuals with asthma, sinusitis, and rhinitis. Furthermore, nasal mucosal tissue from allergic rhinitics produces epsilon germline transcripts following ex vivo allergen challenge. Collectively, these studies raised the possibility that switching to IgE may occur locally, at sites of allergic inflammation. Although epsilon germline transcripts are considered necessary to target the IgE locus, it is class switch recombination that ultimately leads to de novo IgE production. In this study, we demonstrate that S epsilon S mu DNA switch circles (products of class switch recombination) as well as I epsilon and C epsilon RNA are produced within nasal tissue from allergic individuals following ex vivo allergen challenge. epsilon germline transcription was inhibited when tissue was cultured with a combination of allergen and neutralizing Abs against IL-4 and IL-13, indicating that de novo cytokine production mediated the isotype switch. We also show allergen-induced appearance of S epsilon S gamma DNA switch circles and up-regulation of C gamma 4 mRNA, illustrating that sequential switching to IgE also occurred. This work strongly suggests that B cells residing within the nasal mucosa undergo switching to IgE in the context of a local immune response to allergen.

Allergens↗
PubMed2003

Genetic polymorphism in allergy and asthma.

The impact of genetic factors on the pathogenesis of allergy and asthma is currently an area of intense investigation. Although epidemiological studies find more and more genes that are likely to contribute to allergic inflammation, functional studies of the mechanisms that link genetic variation with dysregulation of gene expression and function are hindered by the high frequency of natural variation. The interplay between genes and environment adds another layer of complexity to the determination of allergic phenotypes. The complexity emerging from these studies warrants novel experimental strategies and bolder conceptual paradigms.

Animals↗
PubMed2003

Single-nucleotide polymorphisms in the Toll-like receptor 9 gene (TLR9): frequencies, pairwise linkage disequilibrium, and haplotypes in three U.S. ethnic groups and exploratory case-control disease association studies.

TLR9 is a mammalian Toll-like receptor homologue that appears to function as an innate immune pattern recognition protein for motifs that are far more common in bacterial than in mammalian DNA. The gene was sequenced in 71 subjects from three self-identified U.S. ethnic groups to identify single-nucleotide polymorphisms (SNPs). A total of 20 SNPs were found of which only 20% were in the public dbSNP database. Four SNPs were relatively common in all three ethnic samples. Using these four SNPs, seven distinct haplotypes were statistically inferred, of which four accounted for 75% or more chromosomes. These four haplotypes could be distinguished from each other by the alleles of two SNPs (-1237 and 2848). Five exploratory nested case-control disease-association studies (asthma, DVT, MI, and COPD in European Americans and asthma in African Americans) were performed by genotyping DNA collected from four ongoing cohort studies. There was evidence suggesting increased risk for asthma with a C allele at -1237 (odds ratio 1.85, 95%CI 1.05 to 3.25) among European Americans (genotypes available from 67 cases and 152 controls). No other significant disease associations were detected. Replication of this finding in other, larger samples is needed. This study suggests that there is substantial diversity in human TLR9, possibly associated with asthma in Europeans but not African Americans. No association was detected with three other diseases potentially related to innate immunity.

Black People↗
PubMed2003

Innate immunity: sensing the environment and regulating the regulators.

PURPOSE OF REVIEW: Innate immune cells act as sensors for environmental pathogens and key regulators of pathogen-specific T-cell effector responses. The expression of Toll-like receptors is essential for these functions. Innate immunity is a rapidly evolving field. Great progress has been made in the past year in characterizing the signaling pathways downstream of Toll-like receptors, and the role of Toll-like receptors in the regulation of pathogen responses. RECENT FINDINGS: The ability to control the activation of regulatory T cells has emerged as a key function of innate immunity. Regulatory T cells are involved in the induction of tolerance and the prevention of harmful immune pathology, particularly T-cell responses directed against self-antigens. Toll-like receptor-mediated interactions between pathogen-stimulated innate immune cells and regulatory T cells result in the release of suppression by regulatory T cells, thus allowing pathogen-specific responses. However, pathogenic microorganisms may exploit this interaction to evade the host's response. In addition, recent studies raise the possibility that regulatory T cells may express some Toll-like receptor family members, thereby responding directly to pathogens. SUMMARY: A deeper understanding of the complex role of innate immune cells as sensors of the environment and regulators of pathogen responses will probably influence the current models of immune regulation, particularly those centered on the role of the environment in shaping immune responses.

CD4-Positive T-Lymphocytes↗
PubMed2003

Arginase: marker, effector, or candidate gene for asthma?

Microarray analysis of the expression profiles of lung tissue in two murine models of asthma revealed high levels of arginase I and arginase II activity, in association with IL-4 and IL-13 overexpression, suggesting that arginine pathways are critical in the pathogenesis of asthma.

Animals↗