Inflammatory Biomarkers Can Differentiate Acute Lymphoblastic Leukemia with Arthropathy from Juvenile Idiopathic Arthritis Better Than Standard Blood Tests.

OBJECTIVE: To evaluate the predictive value of biomarkers of inflammation like phagocyte-related S100 proteins and a panel of inflammatory cytokines in order to differentiate the child with acute lymphoblastic leukemia (ALL) from juvenile idiopathic arthritis (JIA). STUDY DESIGN: In this cross-sectional study, we measured S100A9, S100A12, and 14 cytokines in serum from children with ALL (n = 150, including 27 with arthropathy) and JIA (n = 236). We constructed predictive models computing areas under the curve (AUC) as well as predicted probabilities in order to differentiate ALL from JIA. Logistic regression was used for predictions of ALL risk, considering the markers as the respective exposures. We performed internal validation using repeated 10-fold cross-validation and recalibration, adjusted for age. RESULTS: In ALL, the levels of S100A9, S100A12, interleukin (IL)-1 beta, IL-4, IL-13, IL-17, matrix metalloproteinase-3, and myeloperoxidase were low compared with JIA (P < .001). IL-13 had an AUC of 100% (95% CI 100%-100%) due to no overlap between the serum levels in the 2 groups. Further, IL-4 and S100A9 had high predictive performance with AUCs of 99% (95% CI 97%-100%) and 98% (95% CI 94%-99%), respectively, exceeding both hemoglobin, platelets, C-reactive protein, and erythrocyte sedimentation rate. CONCLUSIONS: The biomarkers S100A9, IL-4, and IL-13 might be valuable markers to differentiate ALL from JIA.

Interleukin-18 diagnostically distinguishes and pathogenically promotes human and murine macrophage activation syndrome.

Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperferritinemic systemic inflammatory disorders. Although profound cytotoxic impairment causes familial HLH (fHLH), the mechanisms driving non-fHLH and MAS are largely unknown. MAS occurs in patients with suspected rheumatic disease, but the mechanistic basis for its distinction is unclear. Recently, a syndrome of recurrent MAS with infantile enterocolitis caused by NLRC4 inflammasome hyperactivity highlighted the potential importance of interleukin-18 (IL-18). We tested this association in hyperferritinemic and autoinflammatory patients and found a dramatic correlation of MAS risk with chronic (sometimes lifelong) elevation of mature IL-18, particularly with IL-18 unbound by IL-18 binding protein, or free IL-18. In a mouse engineered to carry a disease-causing germ line NLRC4T337S mutation, we observed inflammasome-dependent, chronic IL-18 elevation. Surprisingly, this NLRC4T337S-induced systemic IL-18 elevation derived entirely from intestinal epithelia. NLRC4T337S intestines were histologically normal but showed increased epithelial turnover and upregulation of interferon-γ-induced genes. Assessing cellular and tissue expression, classical inflammasome components such as Il1b, Nlrp3, and Mefv predominated in neutrophils, whereas Nlrc4 and Il18 were distinctly epithelial. Demonstrating the importance of free IL-18, Il18 transgenic mice exhibited free IL-18 elevation and more severe experimental MAS. NLRC4T337S mice, whose free IL-18 levels were normal, did not. Thus, we describe a unique connection between MAS risk and chronic IL-18, identify epithelial inflammasome hyperactivity as a potential source, and demonstrate the pathogenicity of free IL-18. These data suggest an IL-18-driven pathway, complementary to the cytotoxic impairment of fHLH, with potential as a distinguishing biomarker and therapeutic target in MAS.

Fecal phagocyte-specific S100A12 for diagnosing necrotizing enterocolitis.

OBJECTIVE: To determine whether longitudinal measurements of fecal S100A12, a fecal marker of intestinal inflammation, can identify very low birth weight infants at risk for necrotizing enterocolitis (NEC). STUDY DESIGN: This prospective study included 145 preterm infants with birth weight <1500 g. Meconium and stool samples (n = 843) were collected prospectively on alternate days for 4 weeks, and fecal S100A12 and calprotectin were measured by enzyme-linked immunosorbent assay. RESULTS: Eighteen patients (12.4%) developed NEC. Gestational age and birth weight were significantly lower in the patients with NEC compared with unaffected reference infants. Fecal S100A12 levels were significantly higher in patients with severe NEC at onset of disease and also, in contrast to fecal calprotectin, at 4-10 days before onset of NEC compared with unaffected reference infants (ideal cutoff value, 65 µg/kg; sensitivity, 0.76; specificity, 0.56). CONCLUSIONS: Fecal S100A12 level may be a helpful marker for predicting disease severity and early risk assessment for subsequent development of NEC. However, the use of fecal S100A12 as a predictive biomarker for NEC in very low birth weight infants may be limited due to a high interindividual and intraindividual variability in S100A12 fecal excretion.