Hemophagocytic lymphohistiocytosis as an etiology of bone marrow failure

Deep insight into cytokine storm: from pathogenesis to treatment

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

Hemophagocytic lymphohistiocytosis as the initial manifestation of bone marrow failure in a child with a TERC variant telomere biology disorder

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening systemic hyperinflammatory syndrome, rarely associated with bone marrow failure (BMF). Telomere biology disorders (TBD) are caused by inherited defects in telomerase processes and can have heterogeneous presentations including idiopathic pulmonary fibrosis, cirrhosis, and BMF. We report a case of a 10-year-old male from Lima, Peru, who presented with HLH as the initial manifestation of a TBD. He experienced fever, gastrointestinal symptoms, and mucocutaneous involvement. Initial laboratory analyses revealed pancytopenia and elevated inflammatory markers. Despite symptomatic and antibiotic treatment, his clinical condition persisted leading to a suspicion of Kawasaki disease and, subsequently, HLH. Immunomodulatory treatment was initiated with a good clinical response. Bone marrow aspiration revealed severe hypocellular bone marrow and cytophagocytosis. Genetic studies identified a pathogenic variant in the TERC gene (n.110_113del), which was also found in the patient's mother and brother. HLH as the initial manifestation of BMF is rare. This case highlights the importance of considering TBD in children with BMF of unclear etiology and the value of genetic testing in such cases.

Hemophagocytic Lymphohistiocytosis Syndrome: A Rare Manifestation of Acute Pancreatitis

Hemophagocytic lymphohistiocytosis syndrome (HLH) is a rare hyperinflammatory disorder linked to acute pancreatitis. While there are only a few case reports available on this particular association, we would like to share the case of a 60-year-old man who experienced acute-onset abdominal pain typical of pancreatitis. Three days after admission, he developed fever, pancytopenia, hypertriglyceridemia, and hyperferritinemia. A bone marrow biopsy performed for evaluation of fever revealed hemophagocytosis. Initiation of treatment for HLH showed dramatic improvement. It is important to note that while HLH may be rarely associated with pancreatitis, early diagnosis and treatment is critical and can be life-saving.

Identification of miRNAs that target Fcγ receptor-mediated phagocytosis during macrophage activation syndrome

Macrophage activation syndrome (MAS) is a life-threatening complication of systemic juvenile arthritis, accompanied by cytokine storm and hemophagocytosis. In addition, COVID-19-related hyperinflammation shares clinical features of MAS. Mechanisms that activate macrophages in MAS remain unclear. Here, we identify the role of miRNA in increased phagocytosis and interleukin-12 (IL-12) production by macrophages in a murine model of MAS. MAS significantly increased F4/80+ macrophages and phagocytosis in the mouse liver. Gene expression profile revealed the induction of Fcγ receptor-mediated phagocytosis (FGRP) and IL-12 production in the liver. Phagocytosis pathways such as High-affinity IgE receptor is known as Fc epsilon RI -signaling and pattern recognition receptors involved in the recognition of bacteria and viruses and phagosome formation were also significantly upregulated. In MAS, miR-136-5p and miR-501-3p targeted and caused increased expression of Fcgr3, Fcgr4, and Fcgr1 genes in FGRP pathway and consequent increase in phagocytosis by macrophages, whereas miR-129-1-3p and miR-150-3p targeted and induced Il-12. Transcriptome analysis of patients with MAS revealed the upregulation of FGRP and FCGR gene expression. A target analysis of gene expression data from a patient with MAS discovered that miR-136-5p targets FCGR2A and FCGR3A/3B, the human orthologs of mouse Fcgr3 and Fcgr4, and miR-501-3p targets FCGR1A, the human ortholog of mouse Fcgr1. Together, we demonstrate the novel role of miRNAs during MAS pathogenesis, thereby suggesting miRNA mimic-based therapy to control the hyperactivation of macrophages in patients with MAS as well as use overexpression of FCGR genes as a marker for MAS classification.

A Unique Case of Adult-Onset Still's Disease Not Responsive to Steroid Treatment

A 53-year-old patient was admitted to the emergency department, presenting with fever, generalized weakness, and various myalgias and arthralgias lasting over seven days. Based upon the patient's worsening symptoms, elevated white blood cell count with neutrophilia and overall presentation, she was initially treated for an infectious cause and prescribed various antibiotics and antipyretic medications. As the patient's condition continued to worsen throughout the initial days of her intake, she was tested for a variety of infections, including coronavirus disease 2019 (COVID-19), Streptococcus, and influenza, and was administered a viral respiratory panel, all of which resulted negative. Upon the development of an evanescent rash on hospital day 9, as well as other symptoms including sore throat, arthritis, and an elevated fever present for over a week, a rheumatology consult now expressed concern for a possible case of Adult-Onset Still's Disease (AOSD). In line with the current treatment used for AOSD and the absence of all other infectious causes, the patient discontinued antibiotic treatment and was started on 125 milligrams of intravenous methylprednisolone every six hours. The patient showed minor improvements in symptoms over the next 24 hours but soon became refractory to treatment, resulting from multiorgan damage, and expired on hospital day 13.

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.

Diagnosis and Management of Adult Malignancy-Associated Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of severe, dysregulated inflammation driven by the inability of T cells to clear an antigenic target. When associated with malignancy (mHLH), the HLH syndrome is typically associated with extremely poor survival. Here, we review the diagnosis of secondary HLH (sHLH) syndromes in adults, with emphasis on the appropriate workup and treatment of mHLH. At present, the management of HLH in adults, including most forms of mHLH, is based on the use of corticosteroids and etoposide following the HLH-94 regimen. In some cases, this therapeutic approach may be cohesively incorporated into malignancy-directed therapy, while in other cases, the decision about whether to treat HLH prior to initiating other therapies may be more complicated. Recent studies exploring the efficacy of other agents in HLH, in particular ruxolitinib, offer hope for better outcomes in the management of mHLH. Considerations for the management of lymphoma-associated mHLH, as well as other forms of mHLH and immunotherapy treatment-related HLH, are discussed.