RNA Seq profiling reveals a novel expression pattern of TGF-β target genes in human blood eosinophils

Abstract

Despite major advances in our understanding of TGF-β signaling in multiple cell types, little is known about the direct target genes of this pathway in human eosinophils. These cells constitute the major inflammatory component present in the sputum and lung of active asthmatics and their numbers correlate well with disease severity. During the transition from acute to chronic asthma, TGF-β levels rise several fold in the lung which drives fibroblasts to produce extracellular matrix (ECM) and participate in airway and parenchymal remodeling. In this report, we use purified blood eosinophils from healthy donors and analyze baseline and TGF-β responsive genes by RNA Seq, and demonstrate that eosinophils (PBE) express 7,981 protein-coding genes of which 178 genes are up-regulated and 199 genes are down-regulated by TGF-β. While 18 target genes have been previously associated with asthma and eosinophilic disorders, the vast majority have been implicated in cell death and survival, differentiation, and cellular function. Ingenuity pathway analysis revealed that 126 canonical pathways are activated by TGF-β including iNOS, TREM1, p53, IL-8 and IL-10 signaling. As TGF-β is an important cytokine for eosinophil function and survival, and pulmonary inflammation and fibrosis, our results represent a significant step toward the identification of novel TGF-β responsive genes and provide a potential therapeutic opportunity by selectively targeting relevant genes and pathways.

IL‐3 up‐regulates and activates human eosinophil CD32 and αMβ2 integrin causing degranulation

“…In accordance with precedent quantitative proteomic and RNAseq analyses [43, 44], we did not detect FCGRI (CD64) nor FCGRIII (CD16) on eosinophils. Therefore, CD32 was most likely the candidate that could trigger the interaction with aggregated IgG.…”

IL‐5‐stimulated eosinophils adherent to periostin undergo stereotypic morphological changes and ADAM8‐dependent migration

“…In a recently published quantitative proteomic data set of purified (unstimulated) blood eosinophils pooled from three individuals, eight metalloproteinases were detected in the following order of abundance: ADAM (disintegrin metalloproteinase) 8 (100% relative abundance), MMP (matrix metalloproteinase) 25 (58%), ADAM10 (17%), ADAM19 (3.8%), MMP9 (2.1%), ADAM17 (0.85%), MMP8 (0.41%) and ADAM28 (0.24%) . Consistent with the proteomics data, ADAM8 and MMP25 were by far the most abundant metalloproteinase transcripts in a recent RNA Seq analysis of human blood eosinophils . Eosinophils express relatively high levels of cell‐surface ADAM8 at baseline, as assayed by flow cytometry .…”

“…41 Consistent with the proteomics data, ADAM8 and MMP25 were by far the most abundant metalloproteinase transcripts in a recent RNA Seq analysis of human blood eosinophils. 42 Eosinophils express relatively high levels of cell- surface ADAM8 at baseline, as assayed by flow cytometry. 36 For these reasons, we examined the role of ADAMs, especially ADAM8, in eosinophil-mediated periostin clearance, using the ADAM inhibitor TAPI-1 37…”

Revisiting the NIH Taskforce on the Research needs of Eosinophil-Associated Diseases (RE-TREAD)

“…Other studies show the value of applying transcriptomics to human eosinophil biology, with evolution from gene array studies to RNAseq methodology. Gene array analysis showed upregulated transcripts in bronchoalveolar lavage eosinophils after segmental allergen challenge, and TGF‐β target genes in peripheral blood eosinophils were shown to be expressed by RNAseq . Transcriptome analysis of esophageal tissue specimens was shown to be effective in making molecular diagnoses of EoE and differentiating EoE from reflux disease, and glycomics analyses are being used to identify glycoproteins in mucins and other endogenous tissue structures capable of directly interacting with eosinophil lectin receptors further paving the way for personalized approaches to diagnosis of EADs.…”