Eosinophil Peroxidase Catalyzed Protein Carbamylation Participates in Asthma

Wang, Zeneng; DiDonato, Joseph A.; Buffa, Jennifer A.; Comhair, Suzy; Aronica, Mark A.; Dweik, Raed A.; Lee, Nancy A.; Lee, James J.; Thomassen, Mary Jane; Kavuru, Mani S.; Erzurum, Serpil C.; Hazen, Stanley L.

doi:10.1074/jbc.m116.750034

Cited by 31 publications

(25 citation statements)

References 94 publications

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“…EPX itself can generate antibacterial reactive oxygen metabolites 21,67 and has been implicated directly in specific nitrosylation and carbamoylation reactions in vivo. 68,69 Furthermore, as shown here, EPX −/− mice display diminished recruitment of eosinophils to the lungs, and, of the eosinophils that are recruited, a smaller proportion are TLR4 + . Given these findings, we asked whether eosinophils, as a component of A. alternatamediated inflammation, might be effective in clearing gram-negative nontypeable Haemophilus influenzae (NTHi) from the airways, and whether EPX deficiency might have an impact on this activity; this was addressed via the protocol shown in Fig.…”

Section: A Alternata-challenged Epx −/− Mice Were No Less Effective supporting

confidence: 55%

“…EPX itself can generate anti-bacterial reactive oxygen metabolites [21, 67] and has been implicated directly in specific nitrosylation and carbamoylation reactions in vivo [68, 69]. Furthermore, as shown here, EPX -/- mice display diminished recruitment of eosinophils to the lungs, and, of the eosinophils that are recruited, a smaller proportion are TLR4 + .…”

Section: Resultsmentioning

confidence: 63%

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Impact of eosinophil-peroxidase (EPX) deficiency on eosinophil structure and function in mouse airways

Percopo¹,

Krumholz²,

Fischer³

et al. 2018

Journal of Leukocyte Biology

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Eosinophil-peroxidase (EPX) is a major constituent of the large cytoplasmic granules of both human and mouse eosinophilic leukocytes. Human EPX-deficiency is a rare, autosomal-recessive disorder limited to the eosinophil lineage. Our intent was to explore the impact of EPX gene-deletion on eosinophil content, structure and function. In response to repetitive intranasal challenge with a filtrate of the allergen, Alternaria alternata, we found significantly fewer eosinophils peripherally and in the respiratory tracts of EPX-/- mice compared to wild-type controls; furthermore, both the major population (Gr1-/lo) and the smaller population of Gr1hi eosinophils from EPX-/- mice displayed lower MFIs for Siglec F. Quantitative evaluation of transmission electron micrographs of lung eosinophils confirmed the relative reduction in granule outer matrix volume in cells from the EPX-/- mice, a finding analogous to that observed in human EPX deficiency. Despite the reduced size of the granule matrix, the cytokine content of eosinophils isolated from allergen-challenged EPX-/- and wild-type mice were largely comparable to one another, although the EPX-/- eosinophils contained reduced concentrations of IL-3. Other distinguishing features of lung eosinophils from allergen-challenged EPX-/- mice included a reduced fraction of surface TLR4-positive cells and reduced MFI for NOD1. Interestingly, the EPX gene-deletion had no impact on eosinophil-mediated clearance of gram-negative Hemophilius influenzae from the airways. As such, although no clinical findings have been associated with human EPX-deficiency, our findings suggest that further evaluation for alterations in eosinophil structure and function may be warranted.

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Section: A Alternata-challenged Epx −/− Mice Were No Less Effective supporting

confidence: 55%

Section: Resultsmentioning

confidence: 63%

Impact of eosinophil-peroxidase (EPX) deficiency on eosinophil structure and function in mouse airways

Percopo¹,

Krumholz²,

Fischer³

et al. 2018

Journal of Leukocyte Biology

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“…However, the extensive degranulation in I5/hE2 mice leading to the release of EPX overcomes this limitation and in doing so demonstrated that the release of EPX is actually a modifier of IL-13-mediated events that enhances GM/MA. Our recent mechanistic studies demonstrating that the peroxidase activities of EPX mediate carbamylation of lung proteins provide a mechanistic explanation of this effect (62). Specifically, these carbamylated proteins were shown to have direct agonist activities on airway epithelia leading to goblet cell metaplasia and increased mucin gene expression.…”

Section: Discussionmentioning

confidence: 99%

Lung Pathologies in a Chronic Inflammation Mouse Model Are Independent of Eosinophil Degranulation

Jacobsen

Ochkur

Doyle

et al. 2017

Am J Respir Crit Care Med

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Rationale: The release of eosinophil granule proteins in the lungs of patients with asthma has been dogmatically linked with lung remodeling and airway hyperresponsiveness. However, the demonstrated inability of established mouse models to display the eosinophil degranulation occurring in human subjects has prevented a definitive in vivo test of this hypothesis.Objectives: To demonstrate in vivo causative links between induced pulmonary histopathologies/lung dysfunction and eosinophil degranulation.Methods: A transgenic mouse model of chronic T-helper cell type 2-driven inflammation overexpressing IL-5 from T cells and human eotaxin 2 in the lung (I5/hE2) was used to test the hypothesis that chronic histopathologies and the development of airway hyperresponsiveness occur as a consequence of extensive eosinophil degranulation in the lung parenchyma.Measurement and Main Results: Studies targeting specific inflammatory pathways in I5/hE2 mice surprisingly showed that eosinophil-dependent immunoregulative events and not the release of individual secondary granule proteins are the central contributors to T-helper cell type 2-induced pulmonary remodeling and lung dysfunction. Specifically, our studies highlighted a significant role for eosinophil-dependent IL-13 expression. In contrast, extensive degranulation leading to the release of major basic protein-1 or eosinophil peroxidase was not causatively linked to many of the induced pulmonary histopathologies. However, these studies did define a previously unappreciated link between the release of eosinophil peroxidase (but not major basic protein-1) and observed levels of induced airway mucin.Conclusions: These data suggest that improvements observed in patients with asthma responding to therapeutic strategies ablating eosinophils may occur as a consequence of targeting immunoregulatory mechanisms and not by simply eliminating the destructive activities of these purportedly end-stage effector cells.

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“…Given that IL-13 levels in OVA-treated WT and I5/hE2 mice were virtually identical, this suggests that the release of granule proteins in the lungs of I5/hE2 mice enhances the GM/MA linked with IL-13 expression. Indeed, our recent studies demonstrating that the peroxidase activities of EPX in the lung elicit a posttranslational protein modification, known as carbamylation, provides a mechanism of the enhanced GM/M observed in I5/hE2 relative to I5/hE2/MBP-1 2/2 /EPX 2/2 mice [40]. Specifically, these new studies have shown that carbamylated proteins have direct agonist activities on airway epithelial cells, leading to goblet cell metaplasia and increased mucin gene expression.…”

Section: Discussionmentioning

confidence: 94%

Frontline Science: Eosinophil-deficient MBP-1 and EPX double-knockout mice link pulmonary remodeling and airway dysfunction with type 2 inflammation

Ochkur

Doyle

Jacobsen

et al. 2017

Journal of Leukocyte Biology

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Eosinophils and the release of cationic granule proteins have long been implicated in the development of the type 2-induced pathologies linked with respiratory inflammation. Paradoxically, the ablation of the two genes encoding the most abundant of these granule proteins, major basic protein-1 () and eosinophil peroxidase (), results in a near collapse of eosinophilopoiesis. The specificity of this lineage ablation and the magnitude of the induced eosinopenia provide a unique opportunity to clarify the importance of eosinophils in acute and chronic inflammatory settings, as well as to identify potential mechanism(s) of action linked with pulmonary eosinophils in those settings. Specifically, we examined these issues by assessing the induced immune responses and pathologies occurring in MBP-1/EPX mice after 1) ovalbumin sensitization/provocation in an acute allergen-challenge protocol, and 2) crossing MBP-1/EPX mice with a double-transgenic model of chronic type 2 inflammation (i.e., I5/hE2). Acute allergen challenge and constitutive cytokine/chemokine expression each induced the accumulation of pulmonary eosinophils in wild-type controls that was abolished in the absence of MBP-1 and EPX (i.e., MBP-1/EPX mice). The expression of MBP-1 and EPX was also required for induced lung expression of IL-4/IL-13 in each setting and, in turn, the induced pulmonary remodeling events and lung dysfunction. In summary, MBP-1/EPX mice provide yet another definitive example of the immunoregulatory role of pulmonary eosinophils. These results highlight the utility of this unique strain of eosinophil-deficient mice as part of in vivo model studies investigating the roles of eosinophils in health and disease settings.

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Eosinophil Peroxidase Catalyzed Protein Carbamylation Participates in Asthma

Cited by 31 publications

References 94 publications

Impact of eosinophil-peroxidase (EPX) deficiency on eosinophil structure and function in mouse airways

Impact of eosinophil-peroxidase (EPX) deficiency on eosinophil structure and function in mouse airways

Lung Pathologies in a Chronic Inflammation Mouse Model Are Independent of Eosinophil Degranulation

Frontline Science: Eosinophil-deficient MBP-1 and EPX double-knockout mice link pulmonary remodeling and airway dysfunction with type 2 inflammation

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