Use of a mouse model to identify a blood biomarker for IFNγ activity in pediatric secondary hemophagocytic lymphohistiocytosis.
Life-threatening cytokine release syndromes include primary (p) and secondary (s) forms of hemophagocytic lymphohistiocytosis (HLH). Below detection in healthy individuals, interferon γ (IFNγ) levels are elevated to measurable concentrations in these afflictions suggesting a central role for this cytokine in the development and maintenance of HLH. Mimicking an infection-driven model of sHLH in mice, we observed that the tissue-derived levels of IFNγ are actually 500- to 2000-fold higher than those measured in the blood. To identify a blood biomarker, we postulated that the IFNγ gene products, CXCL9 and CXCL10 would correlate with disease parameters in the mouse model. To translate this into a disease relevant biomarker, we investigated whether CXCL9 and CXCL10 levels correlated with disease activity in pediatric sHLH patients. Our data demonstrate that disease control in mice correlates with neutralization of IFNγ activity in tissues and that the 2 chemokines serve as serum biomarkers to reflect disease status. Importantly, CXCL9 and CXCL10 levels in pediatric sHLH were shown to correlate with key disease parameters and severity in these patients. Thus, the translatability of the IFNγ-biomarker correlates from mouse to human, advocating the use of serum CXCL9 or CXCL10 as a means to monitor total IFNγ activity in patients with sHLH.
Buatois V
，Chatel L
，Cons L
，Lory S
，Richard F
，Guilhot F
，Johnson Z
，Bracaglia C
，De Benedetti F
，de Min C
，Kosco-Vilbois MH
，Ferlin WG
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Targeting interferon-γ in hyperinflammation: opportunities and challenges.
Interferon-γ (IFNγ) is a pleiotropic cytokine with multiple effects on the inflammatory response and on innate and adaptive immunity. Overproduction of IFNγ underlies several, potentially fatal, hyperinflammatory or immune-mediated diseases. Several data from animal models and/or from translational research in patients point to a role of IFNγ in hyperinflammatory diseases, such as primary haemophagocytic lymphohistiocytosis, various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome, and cytokine release syndrome, all of which are often managed by rheumatologists or in consultation with rheumatologists. Given the effects of IFNγ on B cells and T follicular helper cells, a role for IFNγ in systemic lupus erythematosus pathogenesis is emerging. To improve our understanding of the role of IFNγ in human disease, IFNγ-related biomarkers that are relevant for the management of hyperinflammatory diseases are progressively being identified and studied, especially because circulating levels of IFNγ do not always reflect its overproduction in tissue. These biomarkers include STAT1 (specifically the phosphorylated form), neopterin and the chemokine CXCL9. IFNγ-neutralizing agents have shown efficacy in the treatment of primary haemophagocytic lymphohistiocytosis in clinical trials and initial promising results have been obtained in various forms of secondary haemophagocytic lymphohistiocytosis, including macrophage activation syndrome. In clinical practice, there is a growing body of evidence supporting the usefulness of circulating CXCL9 levels as a biomarker reflecting IFNγ production.
De Benedetti F
，Prencipe G
，Bracaglia C
，Marasco E
，Grom AA
... -
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Monocytes From Patients With Macrophage Activation Syndrome and Secondary Hemophagocytic Lymphohistiocytosis Are Hyperresponsive to Interferon Gamma.
To investigate the activation of the IFNγ signaling pathway in monocytes of patients with secondary hemophagocytic lymphohistiocytosis (sHLH)/macrophage activation syndrome (MAS) and to evaluate whether levels of phosphorylated STAT1 represent a biomarker for the identification of patients at early stages of the disease.
Fresh whole blood samples from pediatric patients with active sHLH/MAS, not receiving (n=10) and receiving glucocorticoids (n=14) at time of sampling, were prospectively collected. As disease control groups, patients with active systemic juvenile idiopathic arthritis (sJIA) without MAS, patients with sHLH/MAS in remission and patients with other rheumatic diseases were also sampled. Whole blood cells were left unstimulated or stimulated with increasing concentrations of IFNγ for 10 minutes and the intracellular Tyrosine (701)-phosphorylated STAT1 (pSTAT1) levels were evaluated in monocytes by flow cytometry.
Monocytes from untreated sHLH/MAS patients showed significantly higher basal levels of pSTAT1 compared to those observed in monocytes from glucocorticoid-treated sHLH/MAS patients and from all the other disease controls. In addition, a significant increase in responsiveness to IFNγ, as assessed by increased levels of pSTAT1 following ex vivo stimulation, was observed in monocytes from untreated sHLH/MAS patients. pSTAT1 levels in monocytes distinguished patients with sHLH/MAS not treated with glucocorticoids from patients with active sJIA or with other rheumatic diseases [AUC, 0.93; 95% confidence interval 0.85-1.00, p<0.001]. Statistically significant correlations between IFNG mRNA levels in whole blood cells, circulating IFNγ levels and pSTAT1 levels in sHLH/MAS monocytes were found.
Our data demonstrating higher basal levels of pSTAT1 as well as a hyperreactivity to IFNγ stimulation in monocytes from patients with sHLH/MAS point to perturbations in the activation of downstream IFNγ signaling pathway as a contributor to the hyperinflammation occurring in these patients. Finally, the observation that glucocorticoids affect pSTAT1 levels in vivo, makes it difficult to consider the measurement of pSTAT1 levels as a biomarker to identify patients at early stages of sHLH/MAS in clinical practice.
Pascarella A
，Bracaglia C
，Caiello I
，Arduini A
，Moneta GM
，Rossi MN
，Matteo V
，Pardeo M
，De Benedetti F
，Prencipe G
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《Frontiers in Immunology》
Biomarkers in Pediatric Hemophagocytic Lymphohistiocytosis With Central Nervous System Involvement: A Cohort Study.
The aim of this study was to analyze the clinical significance of cerebrospinal fluid (CSF) cytokines in hemophagocytic lymphohistiocytosis associated with central nervous system (CNS-HLH).
CSF cytokine levels, including interferon (IFN)-γ, soluble CD25 (sCD25), interleukin (IL)-6, IL-10, IL-18, and CXCL9 were measured at disease onset and during the treatment. Five newly diagnosed patients with demyelination disease were enrolled for comparison.
Sixty-five samples from 36 patients (13 in the CNS group and 23 in the non-CNS group) were detected. Levels of CSF IFN-γ, sCD25, IL-10, IL-18, and CXCL9 in the CNS group were higher than those in the non-CNS group ( P =0.038, <0.001, <0.001, 0.005, and <0.001), and levels of CSF sCD25, IL-10, IL-18, and CXCL9 in the CNS group were higher than those in the demyelination group ( P =0.001, 0.008, 0.004, and 0.003). There was no significant difference in IL-6 levels among the 3 groups ( P =0.339). CSF IFN-γ, sCD25, IL-10, IL-18, and CXCL9 could assist in diagnosing CNS-HLH. The diagnostic efficiency of CSF sCD25, IL-10, and CXCL9 was better, with a cutoff value of 154.64, 1.655, and 19.54 pg/mL, respectively. The area under the curve was >0.9, with sensitivity and specificity >80%. Correlation analysis suggested that in the CNS group, IFN-γ levels in CSF and serum correlated positively ( R =0.459, P =0.007), while there was no correlation between CSF CXCL9 and serum IFN-γ ( P =0.915).
CSF IFN-γ, sCD25, IL-10, IL-18, and CXCL9 levels were significantly higher in HLH patients with CNS involvement than those without and could predict HLH patients with CNS involvement. CSF CXCL9 might be a more sensitive biomarker to CNS-HLH than IFN-γ, while CSF IL-6 does not seem to play a vital role.
Zhao Y
，Ou W
，Wei A
，Ma H
，Zhang L
，Lian H
，Zhang Q
，Wang D
，Li Z
，Zhang R
，Wang T
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