Treatment of familial erythrophagocytic lymphohistiocytosis with cyclosporine A

Cytokine Storm Syndromes Associated with Epstein-Barr Virus

Epstein-Barr virus (EBV) is a ubiquitous and predominantly B cell tropic virus. One of the most common viruses to infect humans, EBV, is best known as the causative agent of infectious mononucleosis (IM). Although most people experience asymptomatic infection, EBV is a potent immune stimulus and as such it elicits robust proliferation and activation of the B-lymphocytes it infects as well as the immune cells that respond to infection. In certain individuals, such as those with inherited or acquired defects affecting the immune system, failure to properly control EBV leads to the accumulation of EBV-infected B cells and EBV-reactive immune cells, which together contribute to the development of often life-threatening cytokine storm syndromes (CSS). Here, we review the normal immune response to EBV and discuss several CSS associated with EBV, such as chronic active EBV infection, hemophagocytic lymphohistiocytosis, and post-transplant lymphoproliferative disorder. Given the critical role for cytokines in driving inflammation and contributing to disease pathogenesis, we also discuss how targeting specific cytokines provides a rational and potentially less toxic treatment for EBV-driven CSS.

Hemophagocytic lymphohistiocytosis: Recent progress in the pathogenesis, diagnosis and treatment

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome that develops as a primary (familial/hereditary) or secondary (non-familial/hereditary) disease characterized in the majority of the cases by hereditary or acquired impaired cytotoxic T-cell (CTL) and natural killer responses. The molecular mechanisms underlying impaired immune homeostasis have been clarified, particularly for primary diseases. Familial HLH (familial hemophagocytic lymphohistiocytosis type 2-5, Chediak-Higashi syndrome, Griscelli syndrome type 2, Hermansky-Pudlak syndrome type 2) develops due to a defect in lytic granule exocytosis, impairment of (signaling lymphocytic activation molecule)-associated protein, which plays a key role in CTL activity [e.g., X-linked lymphoproliferative syndrome (XLP) 1], or impairment of X-linked inhibitor of apoptosis, a potent regulator of lymphocyte homeostasis (e.g., XLP2). The development of primary HLH is often triggered by infections, but not in all. Secondary HLH develops in association with infection, autoimmune diseases/rheumatological conditions and malignancy. The molecular mechanisms involved in secondary HLH cases remain unknown and the pathophysiology is not the same as primary HLH. For either primary or secondary HLH cases, immunosuppressive therapy should be given to control the hypercytokinemia with steroids, cyclosporine A, or intravenous immune globulin, and if primary HLH is diagnosed, immunochemotherapy with a regimen containing etoposide or anti-thymocyte globulin should be started. Thereafter, allogeneic hematopoietic stem-cell transplantation is recommended for primary HLH or secondary refractory disease (especially EBV-HLH).

Etanercept for therapy-resistant macrophage activation syndrome

Macrophage activation syndrome (MAS) is a severe, potentially fatal complication of childhood rheumatic diseases, especially systemic onset juvenile idiopathic arthritis (SoJIA). We report a 4-year-old girl with probable SoJIA who presented with MAS. She did not respond to pulse methyl prednisolone and Cyclosporine A (CsA). She also failed to respond to intravenous immunoglobulin (IVIG) therapy. Etanercept was started, based on the observation of increased serum levels of tumor necrosis factor-alpha (TNF-alpha) in patients with MAS. Her condition improved following etanercept, suggesting that etanercept might have a therapeutic role in resistant MAS.

Clinical features and treatment strategies of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis

Epstein-Barr virus (EBV) is the major triggering factor producing hemophagocytic syndrome or hemophagocytic lymphohistiocytosis (HLH). In this review, diagnostic problems, clinical and histopathological features, and treatment strategies of EBV-HLH have been described. In patients with EBV-HLH, the EBV-infected T cells or natural killer (NK) cells are mostly mono- or oligo-clonally proliferating, where hypercytokinemia plays a major role and causes hemophagocytosis, cellular damage and dysfunction of various organs. Although the majority of EBV-HLH cases develop in apparently immunocompetent children and adolescents, it also occurs in association with infectious mononucleosis, chronic active EBV infection, familial HLH, X-linked lymphoproliferative disease, lymphoproliferative disease like peripheral T-cell lymphoma and NK cell leukemia. In terms of treatment, special therapeutic measures are required to control the cytokine storm generated by EBV and to suppress proliferating EBV-genome-containing cells, because the clinical courses are often fulminant and result in a poor outcome.

Recent developments in the management of haemophagocytic lymphohistiocytosis

Over the past two decades, the underlying pathophysiology of haemophagocytic lymphohistiocytosis (HLH) (synonyms: haemophagocytic syndrome, macrophage activation syndrome) has been well recognised. Cytokine storm plays a major role, which derives from an inappropriate immune reaction caused by proliferating and activated T-cell or natural killer (NK) cells associated with macrophage activation and inadequate apoptosis of immunogenic cells. Many biological parameters reflecting activity of disease or response to treatment have been identified, in particular, serum ferritin has been confirmed to be one of the markers for HLH. The common types of HLH consist of non-hereditary (acquired) infection-associated disease such as Epstein-Barr virus (EBV)-haemophagocytic lymphohistiocytosis (HLH) and hereditary (familial) disease such as FHL, in which, at the molecular level, dysfunctional perforin was clarified. Regarding the therapeutic strategies, prompt differential diagnosis of underlying disease is essential and choice of treatment should be based on the risk (low or high) of prognosis, where either cyclosporin A, steroids or iv. immunoglobulin (IVIG) may be indicated as initial treatment for low-risk patients, with etoposide-containing regimens for high-risk patients. Significant improvement of prognosis has been obtained by incorporating intensive supportive care at the disease onset and prompt introduction of immunosuppressants to control cytokine storm. Subsequent immunochemotherapy and haemopoietic stem cell transplantation have contributed significantly to further improve survival of hereditary and refractory HLH patients.

Management of severe neutropenia with cyclosporin during initial treatment of Epstein-Barr virus-related hemophagocytic lymphohistiocytosis

Severe neutropenia (absolute neutrophil count <500/gl) is probably due to the combined effects of dysregulated cytokine production and chemotherapeutic agents, and is one of the risk factors in the initial treatment of patients with Epstein-Barr virus-related hemophagocytic lymphohistiocytosis (EBV-HLH). We report here 9 cases of neutropenic HLH, of which 8 were treated with cyclosporin (CSA, 2-6 mg/kg/day; continuous infusion, or 6 mg/kg/day; per os, for periods ranging from 9 days to >8 weeks) in the initial neutropenic phase during induction treatment using corticosteroids and etoposide. Five of the 6 cases, in which CSA treatment was started early (before the second week of induction), survived the critical period with recovery of neutrophil counts within a week. The remaining 3 cases, in which CSA was introduced later or not at all, died of infection. Based on these results, we recommend a prompt short-term CSA infusion during neutropenic episodes in the most common treatment regimen of etoposide and corticosteroids in patients with HLH. Improved neutrophil recovery as a result of CSA treatment makes it possible to continue immunochemotherapy safely and obtain improved patient outcomes.

Localization of a gene for familial hemophagocytic lymphohistiocytosis at chromosome 9q21.3-22 by homozygosity mapping

Familial hemophagocytic lymphohistiocytosis (FHL), also known as familial erythrophagocytic lymphohistiocytosis and familial histiocytic reticulosis, is a rare autosomal recessive disorder of early childhood characterized by excessive immune activation. Linkage of the disease gene to an approximately 7.8-cM region between markers D9S1867 and D9S1790 at 9q21.3-22 was identified by homozygosity mapping in four inbred FHL families of Pakistani descent with a combined maximum multipoint LOD score of 6.05. This is the first genetic locus to be described in FHL. However, homozygosity by descent across this interval could not be demonstrated in an additional affected kindred of Arab origin, whose maximum multipoint LOD score was -0.12. The combined sample revealed significant evidence for linkage to 9q markers (LOD score with heterogeneity, 5.00). Identification of the gene(s) involved in the pathogenesis of FHL will contribute to an understanding of the control of T-lymphocyte and macrophage activation, which is central to homeostasis in the immune system.

Biomarker and morphological characteristics of Epstein-Barr virus-related hemophagocytic lymphohistiocytosis

BACKGROUND

Viruses may induce primary as well as secondary hemophagocytic lymphohistiocytosis (HLH), but it may not be possible to discriminate between these two in patients with a negative family history. Among these HLH cases, fulminant and fatal virus-associated hemophagocytic syndrome (VAHS) occurs mostly in relation to Epstein-Barr virus (EBV) infection. Although the immunological characteristics of EB-VAHS were previously reported, data on non-EB-VAHS were sporadic and fragmentary. This study has compared the clearly distinguishable groups of EBV-positive vs. EBV-negative HLH cases.

PROCEDURE

Among 26 patients with EBV-related HLH and 12 patients with non-EBV HLH, peripheral blood mononuclear cell (PBMC) subsets and serum concentrations of cytokines at the active phase of the disease were compared. Blood and bone marrow smears were also compared.

RESULTS AND CONCLUSIONS

The frequency of the CD3+HLADR+ subset in PBMC (median 34.3% vs. 4.8%), of serum concentrations of interferon (IFN)-gamma (median 105 U/ml vs. 2.4 U/ml), and of soluble interleukin-2-receptor (sIL-2R) (median 14,700 U/ml vs. 3,412 U/ml) were significantly different between these two groups. Morphological characteristics were noted for EBV-related HLH cases. Mortality also differed between these two groups, 9/26 vs. 0/12 (P = 0.05). Data indicate pronounced immunological imbalance and poor prognosis in EBV-related HLH cases. These parameters could be useful for determining an EBV involvement as well as risk factors in the early care and treatment of HLH patients.

Familial hemophagocytic lymphohistiocytosis: improved neurodevelopmental outcome after bone marrow transplantation

A child with familial hemophagocytic lymphohistiocytosis (HLH) underwent allogeneic bone marrow transplantation (BMT) at age 5 months. At that time he showed delayed psychomotor development, and computed tomography revealed diffuse calcification. After BMT, a gradual neurodevelopmental normalization was observed. The potential ability of BMT to reverse neurodevelopmental deterioration in HLH should be considered.