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RNA- and ChIP-seq analysis of cytokine treated islets

ABSTRACT: Purpose: In the early phases of T1D development exposure of β-cells to IFNγ, IL-1β, and TNFα is thought to induce β-cell dysfunction and the expression of chemokines and cytokines. These changes are mediated in part by post-translational histone modifications within cis-regulatory regions. The purpose of this study was to determine if prevention of these epigenetic changes can alter cytokine induced gene expression changes. Methods: Pancreatic islets were isolated from both male and female CD1 mice by collagenase digestion and were picked by hand. Hand-picked islets were cultured for four days with 1.6ng/ml IFNγ, 0.25ng/ml IL-1β and 0.16ng/ml TNFα (cytokine) or were left untreated (nocytokine). For RNA-seq islets were collected and processed for NGS using the Illumina TruSeq library prep kit. Chromatin immunoprecipitation (ChIP) was performed using 3μg of anti-H3K4me1 (Abcam) with islets from at least 10 adult ICR mice (8-10 weeks old) exposed to 1.6ng/ml IFNγ, 0.25ng/ml Il-1β and 0.16ng/ml TNFα for four days. DNA from 4 separate ChIP experiments was pooled for library construction and sequencing using the Illumina platform. Results: Comparison of gene expression levels between untreated and cytokine-treated islets resulted in the identification of 205 genes that showed an IFNγ, Il-1β, and TNFα-induced chromatin state change (from repressed or inactive to H3K4me1 enriched, i.e. the de novo regions), or increased H3K4me1 enrichment, that were associated with genes with up-regulated expression in response to IFNγ, Il-1β, and TNFα, and 111 genes with reduced H3K4me1 and down-regulated expression in response to IFNγ, Il-1β, and TNFα. Conclusions: Our study confirms that exposure of islets to pro-inflammatory cytokines induces the expression of chemokines and that these changes are the result of a switch from an inactive to an active chromatin state. Further we show that disruption of the trithorax group complex inhibits the upregulation of pro-inflammatory gene expression.

ORGANISM(S): Mus musculus

PROVIDER: GSE73289 | GEO | 2015/12/01

SECONDARY ACCESSION(S): PRJNA296534

REPOSITORIES: GEO

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Project description:Many cytokines are involved in the pathogenesis of autoimmune diseases and are recognized as relevant therapeutic targets to attenuate inflammation, such as TNFα in RA and IFNα/γ in SLE. To relate the transcriptional imprinting of cytokines in a cell type-specific and disease-specific manner, we generated gene-expression profiles from peripheral monocytes of SLE and RA patients and compared them to in vitro-generated signatures induced by TNFα, IFNα2a and IFNγ. Monocytes from SLE and RA patients revealed disease-specific gene-expression profiles. In vitro-generated signatures induced by IFNα2a and IFNγ showed similar profiles that only partially overlapped with those induced by TNFα. Comparisons between disease-specific and in vitro-generated signatures identified cytokine-regulated genes in SLE and RA with qualitative and quantitative differences. The IFN-responses in SLE and RA were found to be regulated in a STAT1-dependent and STAT1-independent manner, respectively. Similarly, genes recognized as TNFα-regulated were clearly distinguishable between RA and SLE patients. While the activity of SLE monocytes was mainly driven by IFN, the activity from RA monocytes showed a dominance of TNFα that was characterized by STAT1 down-regulation. The responses to specific cytokines were revealed to be disease-dependent and reflected the interplay of cytokines within various inflammatory milieus. This study has demonstrated that monocytes from RA and SLE patients exhibit disease-specific gene-expression profiles, which can be molecularly dissected when compared to in vitro-generated cytokine signatures. The results suggest that an assessment of cytokine-response status in monocytes may be helpful for improvement of diagnosis and selection of the best cytokine target for therapeutic intervention. Expression profiles of human peripheral blood monocytes activated in vivo and stimulated in vitro. Monocytes from patients with SLE and RA and from healthy donors were used for generating disease-specific gene-expression profiles, where these profiles represent in vivo activation of monocytes. In addition, monocytes from healthy donors were stimulated in vitro by cytokines: TNFα, IFNα2a and IFNγ. Cytokine-specific gene-expression profiles were generated by comparing stimulated monocytes with unstimulated ones. TNFα-, IFNα2a- and IFNγ as cytokine-specific gene-expression profiles were compared with RA and SLE, as disease-specific gene-expression profiles.

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RNA- and ChIP-seq analysis of cytokine treated islets

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