Neutrophil Activation and Reduced PSTPIP2 Identified in Pediatric CRMO

Chronic recurrent multifocal osteomyelitis (CRMO) is a pediatric autoinflammatory bone disease with limited biomarkers. In an observational study reported in Arthritis & Rheumatology, researchers analyzed blood from 34 patients and 20 controls using flow cytometry, biochemical assays, and neutrophil transcriptomics. Patients were assessed across untreated, NSAID, zoledronate, and anti-TNF treatment groups, examining neutrophil activation, PSTPIP2 expression, and associations with disease burden.

CRMO neutrophils showed reduced CD62L expression, consistent with chronic activation (p=0.0016), which correlated with MRI lesion burden. PSTPIP2 protein levels were lower (p=0.0006), despite increased messenger RNA expression (p=0.0005) and no coding mutations, suggesting post-transcriptional regulation. Neutrophil activation and PSTPIP2 downregulation were normalized in patients receiving anti-TNF therapy. Unlike findings in mouse models, IL1B and CXCL8 expression were not increased.

Transcriptomic profiling of four patients and three controls identified enrichment of NF-κB signaling, inflammatory, and chemotaxis pathways. Several transcripts correlated with clinical disease measures. These findings support neutrophil involvement in human CRMO and suggest potential biomarker candidates, but do not establish validated clinical tests or a causal treatment effect. Interpretation is limited by the small sample, particularly the transcriptomic subset, and the observational treatment comparisons. Only the abstract was available for this assessment.