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Genetic and Transcriptomic Variation Linked to Neutrophil Granulocyte-Macrophage Colony-Stimulating Factor Signaling
Lee A Denson1, Ingrid Jurickova1, Rebekah Karns1
1Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, University of Cincinnati College of Medicine and the Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
Insights
Low granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling in neutrophils is linked to mutations and increased Crohn's disease complications. This finding highlights the role of intrinsic GM-CSF signaling in pediatric Crohn's disease severity.
Area of Science:
- Immunology
- Genetics
- Gastroenterology
Background:
- Granulocyte-macrophage colony-stimulating factor auto-antibodies (GMAbs) are implicated in Crohn's disease (CD) pathogenesis by suppressing neutrophil-extrinsic GM-CSF signaling.
- This study investigates the clinical, genomic, and functional aspects of neutrophil-intrinsic GM-CSF signaling in pediatric CD.
Purpose of the Study:
- To define associations between neutrophil-intrinsic GM-CSF signaling and clinical outcomes in pediatric inflammatory bowel disease (IBD).
- To identify genetic variants and functional alterations linked to reduced GM-CSF signaling in neutrophils.
Main Methods:
- Whole-exome sequencing was performed on 543 pediatric IBD patients to identify mutations in key signaling pathway genes.
- Neutrophil-intrinsic GM-CSF signaling was quantified using the GM-CSF-induced STAT5 stimulation index (GMSI) in 180 pediatric IBD patients and 26 controls.
- Functional assays assessed neutrophil phospho-protein abundance, bacterial killing capacity, and global gene expression patterns in relation to GMSI levels.
Main Results:
- Missense mutations in CSF2RA and CSF2RB were validated, with CSF2RA A17G carriage significantly higher in individuals with low GMSI (32% vs 10%).
- Neutrophils with low GMSI exhibited impaired Staphylococcus aureus killing (35% vs 17%) and distinct alterations in phospho-protein networks and gene expression.
- A strong association was observed between elevated GMAbs, low GMSI, and increased stricturing behavior in pediatric CD patients (64% vs 7%).
Conclusions:
- Reduced neutrophil-intrinsic GM-CSF signaling is associated with specific CSF2RA missense mutations.
- Low GM-CSF signaling in neutrophils correlates with altered gene expression networks and compromised bacterial killing.
- Impaired neutrophil GM-CSF signaling is a significant risk factor for severe disease complications, including stricturing behavior, in pediatric Crohn's disease.
Background:
Granulocyte-macrophage colony-stimulating factor auto-antibodies (GMAbs) suppress neutrophil-extrinsic GM-CSF signaling and increase risk for stricturing behavior in Crohn's disease (CD). We aimed to define clinical, genomic, and functional associations with neutrophil-intrinsic GM-CSF signaling.
Methods:
Missense mutations in CSF2RA, CSF2RB, JAK2, STAT5A, and STAT5B were identified using whole-exome sequencing in 543 pediatric inflammatory bowel disease (IBD) patients. Neutrophil-intrinsic GM-CSF signaling was defined using the GM-CSF-induced STAT5 stimulation index (GMSI) in 180 pediatric IBD patients and 26 non-IBD controls. Reduced GM-CSF signaling (GMSI-Lo) was defined as the 20th percentile within the control group. Variation in neutrophil phospho-protein abundance, bacterial killing, and the global pattern of gene expression with the GMSI was determined.
Results:
We validated 18 potentially damaging missense mutations in CSF2RA and CSF2RB. CSF2RA A17G carriage increased from 10% in those with intact neutrophil GMSI to 32% in those with low GMSI (P = 0.02). The frequency of reduced Staphylococcus aureus killing increased from 17% in those with intact neutrophil GMSI to 35% in GMSI-Lo neutrophils (P = 0.043). Crohn's disease neutrophils with low GMSI exhibited specific alterations in phospho-protein networks and genes regulating cytokine production, wound healing, and cell survival and proliferation. Stricturing behavior increased from 7% in patients with both low GMAb and intact GMSI to 64% in patients with both elevated GMAb and low GMSI (P < 0.0001).
Conclusions:
Low/normal neutrophil-intrinsic GM-CSF signaling is associated with CSF2RA missense mutations, alterations in gene expression networks, and higher rates of disease complications in pediatric CD.