Changes in Cytokine Profile during Initial Treatment of Pediatric Hemophagocytic Lymphohistiocytosis Associated with Epstein-Barr Virus

Etoposide: A rider on the cytokine storm

For more than 40 years, the epipodophyllotoxin drug etoposide is prescribed to treat cancer. This semi-synthetic compound remains extensively used to treat advanced small-cell lung cancer and in various chemotherapy regimen for autologous stem cell transplantation, and other anticancer protocols. Etoposide is a potent topoisomerase II poison, causing double-stranded DNA breaks which lead to cell death if they are not repaired. It is also a genotoxic compound, responsible for severe side effects and secondary leukemia occasionally. Beyond its well-recognized function as an inducer of cancer cell death (a "killer on the road"), etoposide is also useful to treat immune-mediated inflammatory diseases associated with a cytokine storm syndrome. The drug is essential to the treatment of hemophagocytic lymphohistiocytosis (HLH) and the macrophage activation syndrome (MAS), in combination with a corticosteroid and other drugs. The use of etoposide to treat HLH, either familial or secondary to a viral or parasitic infection, or treatment-induced HLH and MAS is reviewed here. Etoposide dampens inflammation in HLH patients via an inhibition of the production of pro-inflammatory mediators, such as IL-6, IL-10, IL-18, IFN-γ and TNF-α, and reduction of the secretion of the alarmin HMGB1. The modulation of cytokines production by etoposide contributes to deactivate T cells and to dampen the immune stimulation associated to the cytokine storm. This review discussed the clinical benefits and mechanism of action of etoposide (a "rider on the storm") in the context of immune-mediated inflammatory diseases, notably life-threatening HLH and MAS. The question arises as to whether the two faces of etoposide action can apply to other topoisomerase II inhibitors.

Specific cytokine patterns in Epstein-Barr virusassociated hemophagocytic lymphohistiocytosis compared to Kawasaki disease in children

The aim of the study was to test whether the cytokine profile could be used as a marker to differentiate between Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) and Kawasaki disease (KD). A total of 70 hospitalized children with HLH and KD admitted to hospital for the first time from March 2017 to December 2021 were enrolled in this study. Fifty-five healthy children were enrolled as normal controls. All patients and normal controls were tested for the six cytokines including interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α), and interferon-γ (IFN-γ) by flow cytometry. IL-10 and IFN-γ levels were significantly higher in children with EBV-HLH than in the KD, IL-6 was lower in EBV-HLH patients than in the KD. IL-10/IL-6 ratio, IFN-γ/IL-6 ratio and IL10/IFN-γ ratio in children with EBV-HLH were significantly much higher than children in the KD group. When the diagnostic cutoff values of IL-10, IFN-γ, IL-10/IL-6 ratio and IFN-γ/IL-6 ratio were >13.2 pg/ml, >71.0 pg/ml, >0.37 and >1.34, respectively, the sensitivity and specificity of the diagnosis of EBV-HLH disease were 91.7% and 97.1%, 72.2% and 97.1%, 86.1% and 100.0%, and 75.0% and 97.1%, respectively. Notably high IL-10 and IFN-γ and moderately elevated IL-6 suggest the diagnosis of EBV-HLH, while high IL-6 levels with low IL-10 or IFN-γ concentration would suggest KD. Additionally, IL-10/IL-6 ratio or IFN-γ/IL-6 ratio could be used as an index to differentiate between EBV-HLH and KD.