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).
Conflicts of interest:The authors have no financial arrangements with any company whose product figures prominently in the submitted manuscript or with a company making a competing product. Dr. Denson has received grant support from Janssen and holds a patent for the use of GM-CSF auto-antibodies as a diagnostic doi: 10.1093/ibd/izy265 Published online 13 August 2018 test in inflammatory bowel disease. Dr. Dubinsky has served as a consultant for Abbvie, Takeda, Janssen, and Pfizer and has received research support from Abbvie, Janssen, and Prometheus. Dr. Guthery has received research support in the last year from Regeneron Pharmaceuticals. Dr. Leleiko or his immediate family have equity interests in Celgene, Vericel, Ionis, Vertex, and Alnylam, and he has served as a consultant for CRICO. The remaining authors have nothing to declare.
2Denson et al 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.