Emergence of anti-red blood cell antibodies triggers red cell phagocytosis by activated macrophages in a rabbit model of Epstein-Barr virus-associated hemophagocytic syndrome

Murine Models of Secondary Cytokine Storm Syndromes

Hemophagocytic lymphohistiocytosis (HLH) comprises a broad spectrum of life-threatening cytokine storm syndromes, classified into primary (genetic) or secondary (acquired) HLH. The latter occurs in a variety of medical conditions, including infections, malignancies, autoimmune and autoinflammatory diseases, acquired immunodeficiency, and metabolic disorders. Despite recent advances in the field, the pathogenesis of secondary HLH remains incompletely understood. Considering the heterogeneity of triggering factors and underlying diseases in secondary HLH, a large diversity of animal models has been developed to explore pivotal disease mechanisms. To date, over 20 animal models have been described that each recapitulates certain aspects of secondary HLH. This review provides a comprehensive overview of the existing models, highlighting relevant findings, discussing the involvement of different cell types and cytokines in disease development and progression, and considering points of interest toward future therapeutic strategies.

Expression and Clinical Significance of Peripheral Blood IL-17A, IL-22, Tim-3, and gal-9 in Children with Infectious Mononucleosis

To investigate the expression and clinical significance of peripheral blood interleukin (IL)-17A, IL-22, T cell immunoglobulin molecule-3 (Tim-3), and galectin-9 (gal-9) in children with infectious mononucleosis (IM) caused by the Epstein-Barr virus (EBV). Peripheral blood of 54 children with IM (case group) was collected and divided into a liver damage group and a non-liver damage group. During the same period, 20 healthy children were in the control group. IL-17A and IL-22 were measured by enzyme-linked immunosorbent assay. Real-time quantitative polymerase chain reaction was used to measure the mRNA expression of Tim-3 and gal-9. Their correlation with clinical indicators was then analyzed. The IL-17A expression level was higher in the case group than in the control group, while Tim-3, gal-9, and IL-22 were lower than those in the control group. Tim-3 was positively correlated with gal-9, but negatively correlated with IL-17A. Tim-3 and gal-9 were positively correlated with CD4+/CD8+ cells. Conversely, they were negatively correlated with CD3+, CD3+CD8+, white blood cell, lymphocyte (L), alanine transaminase (ALT), aspartate transaminase (AST), glutamyl transpeptidase (GGT), and lactate dehydrogenase (LDH). In the case group, IL-17A was positively correlated with L, GGT, and LDH, but negatively correlated with the natural killer (NK) cell count. IL-17A and IL-22 were positively correlated with CD3+, CD3+CD8+, ALT, and AST, but they were negatively correlated with the ratio of CD4+/CD8+. In the liver damage group, IL-17A, IL-22, CD3+, CD3+CD8+, immunoglobulin A (IgA), IgG, IgM, L, ALT, AST, GGT, LDH, and α-hydroxybutyrate levels were higher than those in the non-liver damage group. However, Tim-3, gal-9, the ratio of CD4+/CD8+, and NK were lower than those in the non-liver damage group. IL-17A, IL-22, Tim-3, and gal-9 are involved in the immune pathogenesis of IM caused by EBV infection in children, which may be related to immune liver injury.

Successful treatment of refractory hyperferritinemic syndromes with canakinumab: a report of two cases

BACKGROUND

Hyperferritinemic syndromes are systemic inflammatory disorders characterized by a dysfunctional immune response, which leads to excessive activation of the monocyte-macrophage system with hypercytokinemia and may pursue a rapidly fatal course.

CASE PRESENTATION

We describe two patients of 11 and 9 years of age with hyperferritinemic syndromes, one with impending macrophage activation syndrome (MAS) and one with overt MAS, who were refractory or intolerant to conventional therapies, but improved dramatically with canakinumab.

CONCLUSIONS

Our report indicates that canakinumab may be efficacious in the management of hyperferritinemic syndromes, including MAS.

Hemophagocytic lymphohistiocytosis (HLH): A heterogeneous spectrum of cytokine-driven immune disorders

Hemophagocytic lymphohistiocytosis (HLH) comprises a group of life-threatening immune disorders classified into primary or secondary HLH. The former is caused by mutations in genes involved in granule-mediated cytotoxicity, the latter occurs in a context of infections, malignancies or autoimmune/autoinflammatory disorders. Both are characterized by systemic inflammation, severe cytokine storms and immune-mediated organ damage. Despite recent advances, the pathogenesis of HLH remains incompletely understood. Animal models resembling different subtypes of HLH are therefore of great value to study this disease and to uncover novel treatment strategies. In this review, all known animal models of HLH will be discussed, highlighting findings on cell types, cytokines and signaling pathways involved in disease pathogenesis and extrapolating therapeutic implications for the human situation.

Co-opting biology to deliver drugs

The goal of drug delivery is to improve the safety and therapeutic efficacy of drugs. This review focuses on delivery platforms that are either derived from endogenous pathways, long-circulating biomolecules and cells or that piggyback onto long-circulating biomolecules and cells. The first class of such platforms is protein-based delivery systems--albumin, transferrin, and fusion to the Fc domain of antibodies--that have a long-circulation half-life and are designed to transport different molecules. The second class is lipid-based delivery systems-lipoproteins and exosomes-that are naturally occurring circulating lipid particles. The third class is cell-based delivery systems--erythrocytes, macrophages, and platelets--that have evolved, for reasons central to their function, to exhibit a long life-time in the body. The last class is small molecule-based delivery systems that include folic acid. This article reviews the biology of these systems, their application in drug delivery, and the promises and limitations of these endogenous systems for drug delivery.

MUC16/CA125 in the context of modular proteins with an annotated role in adhesion-related processes: in silico analysis

Mucin 16 (MUC16) is a type I transmembrane protein, the extracellular portion of which is shed after proteolytic degradation and is denoted as CA125 antigen, a well known tumor marker for ovarian cancer. Regarding its polypeptide and glycan structures, as yet there is no detailed insight into their heterogeneity and ligand properties, which may greatly influence its function and biomarker potential. This study was aimed at obtaining further insight into the biological capacity of MUC16/CA125, using in silico analysis of corresponding mucin sequences, including similarity searches as well as GO (gene ontology)-based function prediction. The results obtained pointed to the similarities within extracellular serine/threonine rich regions of MUC16 to sequences of proteins expressed in evolutionary distant taxa, all having in common an annotated role in adhesion-related processes. Specifically, a homology to conserved domains from the family of herpesvirus major outer envelope protein (BLLF1) was found. In addition, the possible involvement of MUC16/CA125 in carbohydrate-binding interactions or cellular transport of protein/ion was suggested.

Macrophage activation syndrome as part of systemic juvenile idiopathic arthritis: diagnosis, genetics, pathophysiology and treatment

Macrophage activation syndrome (MAS) is a severe, frequently fatal complication of systemic juvenile idiopathic arthritis (sJIA) with features of hemophagocytosis leading to coagulopathy, pancytopenia, and liver and central nervous system dysfunction. MAS is overt in 10% of children with sJIA but occurs subclinically in another 30-40%. It is difficult to distinguish sJIA disease flare from MAS. Development of criteria for establishing MAS as part of sJIA are under way and will hopefully prove sensitive and specific. Mutations in cytolytic pathway genes are increasingly being recognized in children who develop MAS as part of sJIA. Identification of these mutations may someday assist in MAS diagnosis. Defects in cytolytic genes have provided murine models of MAS to study pathophysiology and treatment. Recently, the first mouse model of MAS not requiring infection but rather dependent on repeated stimulation through Toll-like receptors was reported. This provides a model of MAS that may more accurately reflect MAS pathology in the setting of autoinflammation or autoimmunity. This model confirms the importance of a balance between pro- and anti-inflammatory cytokines. There has been remarkable progress in the use of anti-pro-inflammatory cytokine therapy, particularly against interleukin-1, in the treatment of secondary forms of MAS, such as in sJIA.

Deciphering the role of Epstein-Barr virus in the pathogenesis of T and NK cell lymphoproliferations

Epstein-Barr virus (EBV) is a highly successful herpesvirus, colonizing more than 90% of the adult human population worldwide, although it is also associated with various malignant diseases. Primary infection is usually clinically silent, and subsequent establishment of latency in the memory B lymphocyte compartment allows persistence of the virus in the infected host for life. EBV is so markedly B-lymphotropic when exposed to human lymphocytes in vitro that the association of EBV with rare but distinct types of T and NK cell lymphoproliferations was quite unexpected. Whilst relatively rare, these EBV-associated T and NK lymphoproliferations can be therapeutically challenging and prognosis for the majority of patients is dismal. In this review, we summarize the current knowledge on the role of EBV in the pathogenesis of these tumours, and the implications for treatment.

Hemophagocytic Lymphohistiocytosis Induced by Severe Pandemic Influenza A (H1N1) 2009 Virus Infection: A Case Report

After early outbreaks in North America in April 2009, the pandemic influenza A (H1N1) virus spread rapidly around the world, and even some patients developed certain severe complications. We reported one case of hemophagocytic lymphohistiocytosis (HLH) induced by severe pandemic influenza A (H1N1) virus infection. A 17-year-old girl had acute onset of fever, dry cough, rhinorrhea, and sore throat Her family members and close friends also had the similar symptoms. Anti-infection treatment with penicillin was given after 8 days of the onset of symptoms in the local hospital, and her chest radiograph showed consolidation of the left lung. Then, she was sent to the People's Hospital of Guizhou Province in China and endotracheal intubation were underwent on the ninth day for acute hypoxic respiratory failure. She was diagnosed with HLH induced by severe pandemic influenza A (H1N1) 2009 virus. Oseltamivir, steroids, immunoglobulin, and plasmapheresis were given immediately after admission. After being treated in the People's Hospital of Guizhou Province for 16 days, she was discharged. This experience shows that HLH may be a life-threatening complication for severe pandemic influenza A (H1N1) 2009 virus infection and responds well to therapy.

Alveolar epithelium protects macrophages from quorum sensing-induced cytotoxicity in a three-dimensional co-culture model

The quorum sensing signal N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C(12) HSL), produced by Pseudomonas aeruginosa, exerts cytotoxic effects in macrophages in vitro, which is believed to affect host innate immunity in vivo. However, the medical significance of this finding to pulmonary disease remains unclear since the multicellular complexity of the lung was not considered in the assessment of macrophage responses to 3-oxo-C(12) HSL. We developed a novel three-dimensional co-culture model of alveolar epithelium and macrophages using the rotating wall vessel (RWV) bioreactor, by adding undifferentiated monocytes to RWV-derived alveolar epithelium. Our three-dimensional model expressed important architectural/phenotypic hallmarks of the parental tissue, as evidenced by highly differentiated epithelium, spontaneous differentiation of monocytes to functional macrophage-like cells, localization of these cells on the alveolar surface and a macrophage-to-epithelial cell ratio relevant to the in vivo situation. Co-cultivation of macrophages with alveolar epithelium counteracted 3-oxo-C(12) HSL-induced cytotoxicity via removal of quorum sensing molecules by alveolar cells. Furthermore, 3-oxo-C(12) HSL induced the intercellular adhesion molecule ICAM-1 in both alveolar epithelium and macrophages. These data stress the importance of multicellular organotypic models to integrate the role of different cell types in overall lung homeostasis and disease development in response to external factors.

Epstein-Barr virus can infect rabbits by the intranasal or peroral route: an animal model for natural primary EBV infection in humans

Epstein-Barr virus (EBV) is spread universally in humans, and it causes infectious mononucleosis and sometimes induces serious EBV-associated disease. The detailed mechanism of primary infection in humans has remained unclear, because it is difficult to examine the dynamics of EBV in vivo. In this study, a natural EBV-infection rabbit model by intranasal or peroral inoculation is described. Ten male rabbits were examined for EBV-DNA or mRNA expression and anti-EBV antibodies in blood. Four of 10 rabbits showed the evidence of EBV infection; detection of EBV-DNA or EBV-related genes mRNA in peripheral blood mononuclear cells, increased EBV antibodies in the plasma, and the presence of lymphocytes expressing EBER1 and EBV-related gene proteins in the lymphoid tissues of a rabbit. Three of four infected rabbits were detected transiently EBV-DNA and/or mRNA of EBV-related genes such as EBNA1, EBNA2, BZLF1, and EA in blood, while in one of four, EBV-DNA and/or mRNA were detected for more than 200 days after viral inoculation. The level of EA-IgG increased and its level was maintained in all infected rabbits, whereas those of VCA-IgM and VCA-IgG increased transiently, and EBNA-IgG was not elevated. Pathological examination of a rabbit infected transiently revealed some scattered lymphocytes expressing EBER1, LMP1, and EBNA2 in the spleen and lymph nodes. EA expression was also observed in the spleen. These findings suggest that EBV can infect the rabbit by the intranasal or peroral route, and that this rabbit model is useful for examining the pathophysiology of natural primary EBV infection in humans.

Plasma cells increased markedly in lymph node in hemophagocytic syndrome: a case report

Introduction

Hemophagocytic syndrome is a rare clinicopathological condition characterized by the activation of the mononuclear phagocyte system, resulting in hemophagocytosis in the reticuloendothelial systems. The pathogenesis of HPS remains unclear.

Case presentation

We report the case of a 20-year-old soldier suffering from HPS. Because of long history fever and no reasons being found, his left groin lymph node and left neck lymph node biopsy were done with two weeks interval. We found a marked increase in plasma cells in left neck lymph node during the course of the disease.

Conclusion

Our result provides a new thought for the researchers to understand the mechanisms responsible for the phagocytosis in HPS.

The immunobiology of viral arthritides

A large range of human viruses are associated with the development of arthritis or arthralgia. Although there are many parallels with autoimmune arthritides, there is little evidence that viral arthritides lead to autoimmune disease. In humans viral arthritides usually last from weeks to months, can be debilitating, and are usually treated with non-steroidal anti-inflammatory drugs, but with variable success. Viral arthritides likely arise from immunopathological inflammatory responses directed at viruses and/or their products residing and/or replicating within joint tissues. Macrophages recruited by monocyte chemoattractant protein-1 (MCP-1/CCL2) and activated by interferon, and proinflammatory mediators like tumour necrosis factor alpha, interferon gamma, interleukin-6 and interleukin-1beta appear to be common elements in this group of diseases. The challenge for new treatments is to target excessive inflammation without compromising anti-viral immunity. Recent evidence from mouse models suggests targeting MCP-1 or complement may emerge as viable new treatment options for viral arthritides.

Up-regulation of activating transcription factor-5 suppresses SAP expression to activate T cells in hemophagocytic syndrome associated with Epstein-Barr virus infection and immune disorders

Hemophagocytic syndrome (HPS) is a fatal, pro-inflammatory cytokine disorder that is associated with viral infections and immune disorders. Previously, we demonstrated that Epstein-Barr virus latent membrane protein-1 (LMP-1) could down-regulate the SAP gene, enhancing Th1 cytokine secretion in T cells and leading to HPS. The exact mechanism of SAP gene regulation by LMP-1 remains to be clarified. In this study, using cDNA microarray analysis, we identified ATF5 as the candidate transcriptional repressor for SAP expression in LMP-1-expressing T cells. LMP-1 up-regulated ATF5 via TRAF2,5/NF-kappaB signals to suppress SAP gene expression. Reporter assays and electrophoretic mobility shift assays revealed that ATF5 bound differentially to two sites of the SAP promoter. In resting T cells, ATF5 bound predominantly to the high-affinity site in the -81 to -74 region while additionally binding to the low-affinity site at -305 to -296 in LMP-1-expressing T cells. Such binding subsequently disrupted the transcription of the SAP gene. At the same time, Th1 cytokine secretion was enhanced. This phenomenon was also observed in conditions such as ATF5 overexpression, phytohemagglutinin stimulation of primary T cells, and ligand engagement of T-cell lines. Therefore, the down-regulation of the SAP gene by ATF5 may represent a common mechanism for the pathogenesis of HPS that is associated with either Epstein-Barr virus infection or immune disorders with dysregulated T-cell activation.

Role of iron homeostasis in trypanosomiasis-associated anemia

Anemia is a well-established infection-associated immunopathological feature of trypanosomiasis and the degree of the anemia is a reliable indicator of the severity of infection. Since infections with trypanosomes triggers a strong cytokine production and a type I immune response, the trypanosome-elicited anemia may be type I cytokine driven. This type of anemia termed anemia of chronic disease is characterized by an imbalance between erythrophagocytosis and erythropoiesis that is linked to a perturbed iron homeostasis including altered iron recycling by macrophages and iron sequestration. To further unravel the mechanisms underlying trypanosome-elicited anemia the expression profile of genes involved in erythrophagocytosis, uptake of iron-containing complexes and iron homeostasis was performed during the acute and chronic phase of experimental Trypanosoma brucei infections in a murine model. The results suggest that liver-associated erythrophagocytosis mediated by cytokine-activated macrophages (M1 cells) is the most likely main initiating event of aggressive anemia during the acute phase of infection. Persistence of strong type I cytokine production during the chronic phase of infection leads to hyper-activated M1 cells and a more progressive anemia. RT-PCR analysis of liver tissue demonstrates a strong increase of cell surface receptors involved in uptake of RBC and iron-containing compounds. For genes involved in iron processing we found an increase of ferroportin-1 (FPN-1), transferrin (Tf) and ceruloplasmin (CP) only in the acute phase, suggesting that export of iron is hampered in the chronic phase of infection. Our results suggest that in the chronic phase of trypanosomiasis, the iron-processing pathway is skewed towards iron sequestration, as evidenced by increased ferritin expression, while enhanced uptake of RBC/iron-containing compounds is maintained.

Pathogenesis and mechanism of disease progression from hemophagocytic lymphohistiocytosis to Epstein-Barr virus-associated T-cell lymphoma: nuclear factor-kappa B pathway as a potential therapeutic target

Epstein-Barr virus (EBV) can infect T lymphocytes and manifests as hemophagocytic lymphohistiocytosis (HLH), a distinct entity of hemophagocytic syndrome (HPS) characterized by fever, hepatosplenomegaly, cytopenia, hypercytokinemia, and systemic macrophage activation with hemophagocytosis. In a substantial percentage of HLH patients, the disease may relapse or progress to T-cell lymphoma in months to years. In the present review, the authors summarize the previous studies on the pathogenesis of HLH and the potential mechanism for the progression of disease from HLH to T-cell lymphoma. The infection of T cells by EBV could activate T cells to secrete proinflammatory cytokines, particularly tumor necrosis factor-alpha (TNF-alpha), which subsequently activate macrophages. EBV latent membrane protein-1 (LMP-1) is the viral product responsible for the activation of the TNF receptor (TNFR) associated factors/nuclear factor-kappaB (NF-kappaB)/ERK pathway to enhance cytokine secretion mediated through the suppression of the SAP/SH2D1A gene. The activation of NF-kappaB will confer resistance to TNF-alpha-induced apoptosis on EBV-infected T cells through the down-regulation of TNFR-1. Consistent with in vitro observations, EBV-associated T or natural killer/T-cell lymphoma showed constitutive activation of NF-kappaB, explaining its drug resistance, hypercytokinemia, and poor prognosis. Therefore, similar to other inflammation-associated cancers, HLH provides a unique model to study the mechanism of disease progression from a benign virus-infected disorder (HLH) to T-cell lymphoma. Inhibition of the NF-kappaB signal pathway should provide a potential target for the treatment of HLH and EBV-associated T-cell lymphoma.