Carbonic Anhydrase IV Is Expressed on IL-5–Activated Murine Eosinophils

Abstract

Eosinophilia and its cellular activation are hallmark features of asthma, as well as other allergic/TH2 disorders, yet there are few, if any, reliable surface markers of eosinophil activation. We have employed a FACS-based genome-wide screening system to identify transcriptional alterations in murine lung eosinophils recruited and activated by pulmonary allergen exposure. Using a relatively stringent screen with false-positive correction, we identified 82 candidate genes that could serve as eosinophil activation markers and/or pathogenic effector markers in asthma. Carbonic anhydrase IV (Car4) was a top dysregulated gene with 36-fold induction in allergen-elicited pulmonary eosinophils, which was validated by quantitative PCR, IHC and by flow cytometry. Eosinophil CAR4 expression was kinetically regulated by IL-5 but not IL-13. IL-5 was both necessary and sufficient for induction of eosinophil CAR4. While CAR4-deficient mice did not have a defect in eosinophil recruitment to the lung nor a change in eosinophil pH-buffering capacity, allergen-challenged chimeric mice that contained Car4−/− hematopoietic cells aberrantly expressed a series of genes enriched in biological processes involved in epithelial differentiation, keratinization, and anion exchange. In conclusion, we have determined that eosinophils express CAR4 following IL-5 or allergen exposure, and that CAR4 is involved in regulating the lung transcriptome associated with allergic airway inflammation; as such, CAR4 has potential value for diagnosing and monitoring eosinophilic responses.

Phenotypic plasticity and targeting of Siglec‐FhighCD11clow eosinophils to the airway in a murine model of asthma

“…To gain additional clues to the role of phenotypic changes of tissue‐recruited eosinophils, we performed secondary analysis of a microarray study contrasting eosinophils isolated from lung tissue of saline vs. OVA‐challenged mice (three challenges; Fig. D) . Consistent with our findings, we identified a significant increase in expression of CD11c ( Itgax ) and Siglec‐F ( Siglec5 ) by allergen‐activated eosinophils.…”

IL-1β in eosinophil-mediated small intestinal homeostasis and IgA production

“…Microarray expression analysis was performed at Cincinnati Children’s Hospital Medical Center’s Chip Core facility, and expression data were analyzed by the software of Genespring GX 11 (Agilent Technologies). The Affymetrix raw expression values were filtered with the significance threshold of 400 as previously reported 56 , 57 and validated by the levels of eosinophil-specific major basic protein gene (also known as proteoglycan 2 [ Prg2 ]) and eosinophil non-expressed glucagon ( Gcg ) ( Fig. S12 ).…”

Profiles of microRNA networks in intestinal epithelial cells in a mouse model of colitis

“…Next we analyzed the target genes that were down-regulated in inflamed large-IECs and the miRNAs whose expression was up-regulated; the expression levels of these miRNAs were validated through quantitative PCR analysis ( Supplementary Figures 6a and 7b ). The target genes of interest in this analysis ( Table 4 ) that were related to IBD include ABCG2 35 , AQP8 36 , and SELENBP1 37 ; those involved in other inflammatory processes include CAR4 38 , CPN1 39 , UNC5B 40 , SCIN 41 , STIM1 42 , and HMMR 43 . The cancer-related genes are RNASEL 44 , DPEP1 45 , MLL3 46 , CDCP1 47 , and KRT20 48 ; those involved in gut homeostasis or immunity are TMIGD1 15 , ARFRP1 16 , and SEPP1 49 .…”