Natural killer cell dysfunction: A common pathway in systemic-onset juvenile rheumatoid arthritis, macrophage activation syndrome, and hemophagocytic lymphohistiocytosis?

Effects of a home-based exercise combined yoga and resistance training in enthesitis-related arthritis in China: study protocol for a randomised controlled trial

INTRODUCTION

Enthesitis-related arthritis (ERA) is a category of juvenile idiopathic arthritis (JIA). The complications of JIA include pain, muscle weakness, limited movement and worsening quality of life. Yoga is an effective exercise therapy for rheumatoid arthritis and may have similar benefits for JIA. Considering the limitation of yoga for strengthening muscles, combined yoga and resistance training (CYRT) may compensate for the shortcomings and provide more benefits for JIA patients. Despite this, there is currently a lack of studies investigating the effectiveness of CYRT for JIA patients. Due to the inaccessibility of traditional exercise therapy, home-based exercise is needed. The study aims to assess the effectiveness of home-based CYRT on JIA.

METHODS AND ANALYSIS

This is a 12-week randomised single-blind controlled trial study. 60 patients with ERA will be randomised into two groups: the home-based exercise group (HBE) and the health education (HE) group. The HBE group (n=30) will perform the CYRT programme 3 times a week at home for 12 weeks and receive HE. The HE group (n=30) will only receive HE. The outcomes include primary outcome (pain levels) and secondary outcomes (lower limb muscle strength, motion range of joint, aerobic fitness, function ability, fatigue levels, mental health, quality of life and blood biomarkers). The assessments will be conducted at baseline, postintervention (12 weeks) and follow-up (24 weeks). Data will be analysed by intention to treat.

ETHICS AND DISSEMINATION

This study has been approved by the Ethics Committee of Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine in December 2023 (approval no. XHEC-C-2023-059-3). This study will require informed consent from all subjects and guardians of children under 18 years of age. The findings will be published in a peer-reviewed journal and international conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2300073446.

Association between Interleukin-17F 7488A/G and 7383A/G polymorphisms and susceptibility to juvenile idiopathic arthritis

BACKGROUND

Interleukin-17F (IL-17F), one of the cytokines, is crucial in the pathophysiology of juvenile idiopathic arthritis (JIA). Therefore, we aimed to determine the relation between IL17F 7488A/G and IL17F 7383A/G single-nucleotide polymorphisms and JIA susceptibility and to explain their impact on the disease activity.

METHODS

Genomic DNA of 70 patients with JIA and 70 age and sex-matched controls were extracted and typed for IL17F 7488A/G and IL17F 7383A/G single-nucleotide polymorphisms, using polymerase chain reaction with sequence-specific primers method, and compared between patients and controls.

RESULTS

When compared to AA participants, children with the AG genotype of the IL17F 7488A/G and IL17F 7383A/G polymorphisms showed a substantially greater risk of JIA. Furthermore, children with the G allele were 2.8 folds more likely to have JIA than the A allele for IL17F 7488A/G polymorphism and 3.72 folds for IL17F 7383A/G polymorphism. Children with AG genotype of IL17F 7383A/G polymorphism were far more likely to have high activity JIA.

CONCLUSIONS

The G allele of both IL17F 7488A/G and IL17F7383 A/G polymorphisms is associated with increased JIA susceptibility, and JIA at High Disease Activity was more likely to develop in AG subjects of the IL17F 7383 A/G polymorphism.

IMPACT

The relationship between Interleukin-17F 7488A/G and 7383A/G polymorphisms and risk for JIA has not been recognized before. Impact of Interleukin-17F 7488A/G and 7383A/G genotypes on JIA disease activity. The G allele of both IL17F 7488A/G and IL17F7383 A/G polymorphisms are associated with increased JIA susceptibility. AG genotype of Interleukin-17F 7383 A/G polymorphism compared to AA patients, had a higher probability of developing JIA at a High Disease Activity (HDA) level.

Hemophagocytic lymphohistiocytosis as a rare complication of dengue haemorrhagic fever: a case report

BACKGROUND

Haemophagocytic lymphohistiocytosis (HLH) is an uncommon systemic inflammatory syndrome that can happen secondary to numerous conditions. It rarely occurs due to dengue infection causing significant mortality and morbidity even with appropriate treatment. The outcome is further poor if the diagnosis of HLH is delayed or left untreated. Therefore, a high degree of clinical suspicion is paramount in diagnosing HLH.

CASE PRESENTATION

A 17-year-old Sinhalese boy was admitted to a tertiary care hospital in Sri Lanka with a 4-day history of fever, headache, nausea, vomiting, and diarrhea. He was hemodynamically stable, and the serological investigation confirmed a dengue infection. On the fifth day of fever, he entered the critical phase of dengue infection, confirmed by ultrasound evidence of plasma leaking. However, he had ongoing high fever spikes during the critical phase, and even after the critical phase was over, the fever spikes continued. Simultaneously, hepatosplenomegaly was noticed, and he showed persistent thrombocytopenia, neutropenia, and anemia despite the resolution of the critical phase. Further, the workup revealed a serum ferritin level of > 3000 ng/mL triglyceride level of 314 mg/dL, and the bone marrow biopsy revealed an increased haemophagocytic activity. Secondary HLH was diagnosed on the basis of criteria used in the HLH-2004 trial and successfully managed with intravenous dexamethasone 10 mg/body surface area/day for the first 2 weeks, followed by a tapering regimen over 8 weeks.

CONCLUSION

This case emphasizes the need to consider HLH as a potential complication when persistent fever and cytopenias are present after recovering from dengue fever, particularly in patients with unusual clinical features like hepatosplenomegaly. Early recognition and prompt treatment with appropriate immunosuppressive therapy, such as intravenous dexamethasone, can lead to a successful response and good prognosis.

Innate and adaptive immunity to SARS-CoV-2 and predisposing factors

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), has affected all countries worldwide. Although some symptoms are relatively mild, others are still associated with severe and even fatal clinical outcomes. Innate and adaptive immunity are important for the control of SARS-CoV-2 infections, whereas a comprehensive characterization of the innate and adaptive immune response to COVID-19 is still lacking and the mechanisms underlying immune pathogenesis and host predisposing factors are still a matter of scientific debate. Here, the specific functions and kinetics of innate and adaptive immunity involved in SARS-CoV-2 recognition and resultant pathogenesis are discussed, as well as their immune memory for vaccinations, viral-mediated immune evasion, and the current and future immunotherapeutic agents. We also highlight host factors that contribute to infection, which may deepen the understanding of viral pathogenesis and help identify targeted therapies that attenuate severe disease and infection.

The Multifaceted Immunology of Cytokine Storm Syndrome

Cytokine storm syndromes (CSSs) are potentially fatal hyperinflammatory states that share the underpinnings of persistent immune cell activation and uninhibited cytokine production. CSSs can be genetically determined by inborn errors of immunity (i.e., familial hemophagocytic lymphohistiocytosis) or develop as a complication of infections, chronic inflammatory diseases (e.g., Still disease), or malignancies (e.g., T cell lymphoma). Therapeutic interventions that activate the immune system such as chimeric Ag receptor T cell therapy and immune checkpoint inhibition can also trigger CSSs in the setting of cancer treatment. In this review, the biology of different types of CSSs is explored, and the current knowledge on the involvement of immune pathways and the contribution of host genetics is discussed. The use of animal models to study CSSs is reviewed, and their relevance for human diseases is discussed. Lastly, treatment approaches for CSSs are discussed with a focus on interventions that target immune cells and cytokines.

Serum cytokine pattern in children with hemophagocytic lymphohistiocytosis

This study aimed to compare the serum levels of 34 cytokines of children with hemophagocytic lymphohistiocytosis (HLH) and explored the specific cytokine pattern of HLH subtypes and the relationship between cytokine levels and prognosis. This retrospective study assessed the clinical data and cytokine levels of newly diagnosed children with HLH in Beijing Children's Hospital, Capital Medical University, from January 2017 to December 2021. A total of 101 children were enrolled in the study. The levels of IFN-γ and IL-18 increased in more than 90% of patients, and MIP-1α, SDF-1α, IP-10, IL-6, IL-8, IL-10, IL-1 RA, and TNF-α increased at different levels in more than 50% of patients. The levels of IL-10 in EBV-HLH increased significantly, followed by IFN-γ and IL-18, while IL-10 and IFN-γ in CAEBV-HLH had a slight increase. Except for IL-10, the levels of IL-6, Eotaxin, IL-13, IL-18, IFN-γ, and MIP-1β in Rh-HLH increased significantly. F-HLH had significantly high IL-10 levels and a slight increase in IL-13. We showed that various cytokines could assist in differentiating HLH subtypes with ROC curve analysis. When IL-10/IL-6 was 1.37, the sensitivity and specificity of diagnosing EBV-HLH were higher than 80% (AUC = 0.837, p < 0.001). The effect of cytokine ratio on classifying HLH subtypes (17/22, 77.3%) was more significant than the single cytokine (5/22, 22.7%). The 3-year overall survival (OS) rate of children with F-HLH was the lowest during the follow-up. The 3-year OS of patients with EBV-HLH and CAEBV-HLH was significantly higher than that with F-HLH (88.1% ± 5.0% vs. 94.1% ± 5.7% vs. 57.1% ± 14.6%, p = 0.017). Cox proportional hazards model revealed that elevated GM-CSF and MCP-1, as well as CNS involvement, were independent risk factors for poor outcomes for patients with HLH. Various cytokines play important roles in HLH. Different subtypes of HLH have their specific cytokines pattern, and the ratio of cytokines may be more significant in differentiating HLH subtypes than the single one. Elevated GM-CSF and MCP-1 could be useful biomarkers for a poor prognosis for patients with HLH.

Clinical spectrum and therapeutic management of systemic lupus erythematosus-associated macrophage activation syndrome: a study of 20 Moroccan adult patients

OBJECTIVE

The objective of this study was to describe the clinical and laboratory manifestations, triggers factors, treatment, and outcome of MAS complicating SLE.

METHODS

We retrospectively analyzed the medical records of adult patients with SLE for a period of 8 years (2009-2016) and identified patients who had developed MAS. We conducted statistical analysis to identify factors associated with MAS.

RESULTS

Among 208 consecutive lupus patients, 20 patients (19 women) were identified having MAS. The mean age of patients was 35.4 ± 10 years. MAS revealed lupus in 7 patients. In the others, the delay between diagnosis of SLE and MAS was 33,3 months. All cases required hospital admission, and 2 patients were admitted to the intensive care unit. An anemia (hemoglobin < 10 g/dL) was found in all patients. A thrombopenia was observed in 19 (95%) cases. Hypertriglyceridemia and hyperferritinemia were present in all patients. All patients had anti-nuclear antibodies and anti-double-stranded DNA antibodies. Bone marrow aspiration showed hemophagocytosis in 15 (94%) cases. The mean SLEDAI was 20.95 corresponding to an SLE of a very high activity. The mean H-Score was 233.85. MAS was associated with a lupus flare in 13 patients. Documented bacterial infections, viral infections, and a breast cancer were respectively diagnosed in 4, 3, and 1 cases respectively. The corticosteroids were administered in all patients. Intravenous cyclophosphamide was used together with corticosteroids in 6 patients, mycophenolate mofetil in 2 cases and azathioprine in 2 cases. Intravenous immunoglobulin was given in 4 cases, etoposide in one case and rituximab was used as the third line treatment in one patient. All infectious episodes were also treated by broad spectrum antibiotics. All patients had a good outcome without any mortality at the management, with a mean follow-up of 24 months. The clinical parameters significantly associated with MAS were fever (p = 0,001), splenomegaly (p < 0.0001), lymphadenopathy (p < 0.0001), oral and/or nasopharyngeal ulceration (p = 0.04), arthritis (p = 0.017), and pulmonary signs (p = 0.003). Laboratory parameters associated with MAS were anemia (p < 0.0001), thrombopenia (p < 0.0001), hyperferritinemia (p < 0.0001), hypertriglyceridemia (p < 0.0001), SLEDAI (p < 0.0001), and H-Score (p < 0.0001). Receiver operating characteristic (ROC) analysis identified optimal cutoff values of ferritin (> 695 ng/mL) and SLEDAI (> 13.5) to predict the occurrence of MAS in SLE.

CONCLUSION

MAS was observed in 9.62% Moroccan adult patients with SLE. SLE flare and infection were the common triggers of MAS in our study. Our study indicates that the occurrence of unexplained fever, splenomegaly, lymphadenopathy, profound cytopenia, hyperferritinemia, hypertriglyceridemia, high SLEDAI, and H-Score should raises the possibility of the diagnosis of MAS in SLE patients. Early diagnosis and urgent therapeutic management improves the overall prognosis. Key Points • Macrophage activation syndrome (MAS) is an underdiagnosed complication of systemic lupus erythematosus (SLE). The prevalence of this complication in this study is nearly 10%. • The diagnosis of MAS represents a major challenge for clinicians, as it could mimic a SLE flare up or be confused with infections. Validated diagnostic criteria for MAS in adults secondary to SLE are urgently needed. • In this study, the H-score calculate the individual risk of adult patients having reactive MAS. The cut-off value for the H-score was 190.5 (sensitivity 96.7%, specificity 97.6%). • The prognosis of MAS with SLE is good in our study. However, in the literature MAS may be a fatal condition in SLE patients. Prospective studies are necessary to confirm these results.

Detection and Prediction of Macrophage Activation Syndrome in Still's Disease

Distinguishing between macrophage activation syndrome (MAS) and a simple flare of Still’s disease (SD) may be challenging. We sought to clarify the clinical features and outcome of MAS in SD and to explore predictive factors of MAS development. Demographic and clinical data, treatments, and outcomes were recorded in a cohort of 206 SD patients. SD patients with and without MAS were compared. To explore predictive factors for the development of MAS, patients were compared at the time of SD diagnosis. Twenty (9.7%) patients experienced MAS, which was inaugural in 12 cases. Patients with MAS were more likely to have hepatomegaly (OR, 3.71; 95% CI, 1.14–11.2; p = 0.03) and neurological symptoms (OR, 4.43; 95% CI, 1.08–15.3; p = 0.04) than patients without MAS. Cytopenias, abnormal liver tests, and coagulation disorders were significantly more frequent in patients with MAS; lactate dehydrogenase and serum ferritin levels were significantly higher. An optimized threshold of 3500 μg/L for serum ferritin yielded a sensitivity (Se) of 85% and a negative predictive value (NPV) of 97% for identifying patients with/without MAS. Survival analysis showed that a high ferritin level at the time of SD diagnosis was predictive of MAS development (p < 0.001). Specific factors, including neurological symptoms, cytopenias, elevated LDH, and coagulopathy, may contribute to the early detection of MAS. Extreme hyperferritinemia at the onset of SD is a prognostic factor for the development of MAS.

Abnormality in the NK-cell population is prolonged in severe COVID-19 patients

BACKGROUND

Our understanding of adaptive immune responses in patients with coronavirus disease 2019 (COVID-19) is rapidly evolving, but information on the innate immune responses by natural killer (NK) cells is still insufficient.

OBJECTIVE

We aimed to examine the phenotypic and functional status of NK cells and their changes during the course of mild and severe COVID-19.

METHODS

We performed RNA sequencing and flow cytometric analysis of NK cells from patients with mild and severe COVID-19 at multiple time points in the course of the disease using cryopreserved PBMCs.

RESULTS

In RNA-sequencing analysis, the NK cells exhibited distinctive features compared with healthy donors, with significant enrichment of proinflammatory cytokine-mediated signaling pathways. Intriguingly, we found that the unconventional CD56dimCD16neg NK-cell population expanded in cryopreserved PBMCs from patients with COVID-19 regardless of disease severity, accompanied by decreased NK-cell cytotoxicity. The NK-cell population was rapidly normalized alongside the disappearance of unconventional CD56dimCD16neg NK cells and the recovery of NK-cell cytotoxicity in patients with mild COVID-19, but this occurred slowly in patients with severe COVID-19.

CONCLUSIONS

The current longitudinal study provides a deep understanding of the NK-cell biology in COVID-19.

Haemophagocytic lymphohistiocytosis in pregnancy

Haemophagocytic lymphohistiocytosis is a life-threatening systemic inflammatory syndrome defined by persistent fever, cytopenia and multi-organ dysfunction. Primary haemophagocytic lymphohistiocytosis classically presents in childhood as a result of genetically abnormal perforin or inflammasome function, leading to the aberrant release of pro-inflammatory cytokines causing a hyperinflammatory state. Secondary haemophagocytic lymphohistiocytosis is an acquired phenomenon occurring at any age as a result of immune dysregulation to a specific trigger such as infection, haematological malignancy or autoimmune disease. Secondary haemophagocytic lymphohistiocytosis occurring in the pregnant woman represents a diagnostic challenge and carries a significant mortality. This has led to its first inclusion in the fourth Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries across the United Kingdom annual maternal report in 2017. This article presents an overview of haemophagocytic lymphohistiocytosis, reviews the literature on haemophagocytic lymphohistiocytosis in pregnancy, suggests diagnostic pathways and explores the safety and efficacy of existing and potential treatment strategies for haemophagocytic lymphohistiocytosis occurring during pregnancy.

Application of Weighted Gene Coexpression Network Analysis to Identify Key Modules and Hub Genes in Systemic Juvenile Idiopathic Arthritis

Systemic juvenile idiopathic arthritis (sJIA) is a severe autoinflammatory disorder with a still not clearly defined molecular mechanism. To better understand the disease, we used scattered datasets from public domains and performed a weighted gene coexpression network analysis (WGCNA) to identify key modules and hub genes underlying sJIA pathogenesis. Two gene expression datasets, GSE7753 and GSE13501, were used to construct the WGCNA. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were applied to the genes and hub genes in the sJIA modules. Cytoscape was used to screen and visualize the hub genes. We further compared the hub genes with the genome-wide association study (GWAS) genes and used a consensus WGCNA to verify that our conclusions were conservative and reproducible across multiple independent datasets. A total of 5,414 genes were obtained for WGCNA, from which highly correlated genes were divided into 17 modules. The red module demonstrated the highest correlation with the sJIA module (r = 0.8, p = 3e⁻²⁹), whereas the green-yellow module was found to be closely related to the non-sJIA module (r = 0.62, p = 1e⁻¹⁴). Functional enrichment analysis demonstrated that the red module was mostly enriched in the activation of immune responses, infection, nucleosomes, and erythrocytes, and the green-yellow module was mostly enriched in immune responses and inflammation. Additionally, the hub genes in the red module were highly enriched in erythrocyte differentiation, including ALAS2, AHSP, TRIM10, TRIM58, and KLF1. The hub genes from the green-yellow module were mainly associated with immune responses, as exemplified by the genes KLRB1, KLRF1, CD160, and KIRs. We identified sJIA-related modules and several hub genes that might be associated with the development of sJIA. Particularly, the modules may help understand the mechanisms of sJIA, and the hub genes may become biomarkers and therapeutic targets of sJIA in the future.

The cytokine storms of COVID-19, H1N1 influenza, CRS and MAS compared. Can one sized treatment fit all?

An analysis of published data appertaining to the cytokine storms of COVID-19, H1N1 influenza, cytokine release syndrome (CRS), and macrophage activation syndrome (MAS) reveals many common immunological and biochemical abnormalities. These include evidence of a hyperactive coagulation system with elevated D-dimer and ferritin levels, disseminated intravascular coagulopathy (DIC) and microthrombi coupled with an activated and highly permeable vascular endothelium. Common immune abnormalities include progressive hypercytokinemia with elevated levels of TNF-α, interleukin (IL)-6, and IL-1β, proinflammatory chemokines, activated macrophages and increased levels of nuclear factor kappa beta (NFκB). Inflammasome activation and release of damage associated molecular patterns (DAMPs) is common to COVID-19, H1N1, and MAS but does not appear to be a feature of CRS. Elevated levels of IL-18 are detected in patients with COVID-19 and MAS but have not been reported in patients with H1N1 influenza and CRS. Elevated interferon-γ is common to H1N1, MAS, and CRS but levels of this molecule appear to be depressed in patients with COVID-19. CD4+ T, CD8+ and NK lymphocytes are involved in the pathophysiology of CRS, MAS, and possibly H1N1 but are reduced in number and dysfunctional in COVID-19. Additional elements underpinning the pathophysiology of cytokine storms include Inflammasome activity and DAMPs. Treatment with anakinra may theoretically offer an avenue to positively manipulate the range of biochemical and immune abnormalities reported in COVID-19 and thought to underpin the pathophysiology of cytokine storms beyond those manipulated via the use of, canakinumab, Jak inhibitors or tocilizumab. Thus, despite the relative success of tocilizumab in reducing mortality in COVID-19 patients already on dexamethasone and promising results with Baricitinib, the combination of anakinra in combination with dexamethasone offers the theoretical prospect of further improvements in patient survival. However, there is currently an absence of trial of evidence in favour or contravening this proposition. Accordingly, a large well powered blinded prospective randomised controlled trial (RCT) to test this hypothesis is recommended.

Macrophage activation syndrome in COVID-19

The novel coronavirus epidemic is characterized by high rates of morbidity and relatively high mortality. Laboratory test results in patients include leukopenia, an increase in liver function tests and ferritin levels reaching hundreds, and sometimes thousands of units. These data remind us about the macrophage activation syndrome (MAC). Secondary hemophagocytic lymphohistiocytosis syndrome, MAC, which pathogenesis is based on a defect in the mechanisms of T-cell cytotoxicity and decreased level of natural killer cells associated with the defect in the perforin-encoding gene as well as hyperproduction of a number of cytokines – interleukin (IL)-1â, tumor necrosis factor-á, etc. by T-lymphocytes and histiocytes, indirectly leading to the activation of macrophages and production of proinflammatory cytokines, in particular IL-6 hyperproduction. MAC is one of "hyperferritinemic syndromes". These disorders have similar clinical and laboratory manifestations, and they also respond to similar treatments, suggesting that hyperferritinemia may be involved in the overall pathogenesis and is characterized by elevated ferritin level and cytokine storm. Despite the fact that data on the immune and inflammatory status in patients with COVID-19 have only started to appear, it is already clear that hyperinflammation and coagulopathy affect the disease severity and increase the risk of death in patients infected with SARS-CoV-2. Hence, understanding the pathogenesis of the novel coronavirus infection can help in its early diagnostics and treatment.

Macrophage activation syndrome: A diagnostic challenge (Review)

Macrophage activation syndrome (MAS) represents an acute and severe inflammatory syndrome, idiopathic (primary) or secondary to infections, rheumatic diseases, malignancies, or drugs. MAS is underdiagnosed, being confused with sepsis, adverse effects of anti-arthritic drugs or exacerbated symptoms of evolving rheumatologic or infectious diseases. Because of the late diagnosis, most patients do not benefit from effective therapy, leading to death. Elucidation of valid early diagnostic criteria of MAS would be a particularly important step in reducing the mortality due to this pathology. Thus, the purpose of this review based on 40 studies centered on the diagnostic criteria of MAS. We detailed the main diagnostic criteria and the few diagnostic scores or sets of criteria that have been recently published. The criteria most frequently encountered in the literature include: Fever, hepatosplenomegaly, hyperferritinemia, hepatopathy, coagulopathy, thrombocytopenia, hypertriglyceridemia, decrease in erythrocyte sedimentation rate and bone marrow hemophagocytosis. The most elaborate diagnostic score will result following an ongoing international project and consensus, the Delphi International Survey.

Do COVID-19 Infections Result in a Different Form of Secondary Hemophagocytic Lymphohistiocytosis

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in significant morbidity and mortality across the world, with no current effective treatments available. Recent studies suggest the possibility of a cytokine storm associated with severe COVID-19, similar to the biochemical profile seen in hemophagocytic lymphohistiocytosis (HLH), raising the question of possible benefits that could be derived from targeted immunosuppression in severe COVID-19 patients. We reviewed the literature regarding the diagnosis and features of HLH, particularly secondary HLH, and aimed to identify gaps in the literature to truly clarify the existence of a COVID-19 associated HLH. Diagnostic criteria such as HScore or HLH-2004 may have suboptimal performance in identifying COVID-19 HLH-like presentations, and criteria such as soluble CD163, NK cell activity, or other novel biomarkers may be more useful in identifying this entity.

Secondary Hemophagocytic Lymphohistiocytosis in a Young Hispanic Adult

Hemophagocytic lymphohistiocytosis (HLH) is a disease caused by a severe immune system reaction that involves an overwhelming inflammatory response with overproduction of cytokines and hemophagocytosis. HLH is classified as primary HLH or familial HLH (PHLH or FHLH) and secondary HLH. PHLH is due to mutations in several genes that regulate immune cells, while secondary HLH is triggered by a severe illness (viral infections or malignancies) that induce an excessive immune response that is difficult to control. We present a case of a young Hispanic adult female with a medical history of diabetes mellitus type 1 and hepatitis E that was diagnosed with HLH secondary to lymphoma caused by Epstein Barr virus infection. The patient was started on broad-spectrum antibiotics and steroid therapy; however, the patient succumbed to the disease. HLH is associated with high mortality, mainly because it is not a very common entity and patients usually present critically ill and deteriorate very fast. Immunosuppression and treatment of the underlying disorder is the target of the treatment of HLH, however, the prognosis remains poor.

IFNAR2 Deficiency Causing Dysregulation of NK Cell Functions and Presenting With Hemophagocytic Lymphohistiocytosis

We describe a 2 year old boy with two previously undescribed frameshift mutations in the interferon (IFN)α/β receptor 2 (IFNAR2) gene presenting with hemophagocytic lymphohistiocytosis (HLH) following measles-mumps-rubella vaccination. Functional analyses show the absence of response to type I IFN in the patient’s cells, as revealed by the lack of phosphorylation of STAT1 and the lack of induction of interferon-stimulated genes upon ex vivo stimulation with IFNα. HLH has been reported in patients with inborn errors of type I IFN-mediated immune responses following vaccination with live-attenuated viruses. The relation between HLH and defective type I IFN-mediated responses is unclear. We show that in patient’s natural killer (NK) cells stimulated with IFNα the expected increase in degranulation and inhibition of IFNγ production were affected. These data support a role for NK cell function dysregulation and lack of inhibition of IFNγ production as contributors to the development of HLH in patients with impaired type I IFN signaling.

Macrophage activation syndrome as an initial presentation of systemic lupus erythematosus

In a recent article on World J Clin Cases 2019; 7: 3859-3865, Sun et al reported a case of 36-year-old female with macrophage activity syndrome as an onset of systemic lupus erythematosus. Although this is a very interesting case, some concerns still need to be addressed. First, the patient had an extremely elevated serum ferritin but a normal C-reactive protein level, which was unparallel with the inflammatory condition before she received any treatments. Second, the diagnosis of systemic lupus erythematosus seemed to be insufficient according to the patient’s medical information presented, most of which were not specific to lupus but could be explained by macrophage activity syndrome. Hence, more medical information on the patient should be provided, and a profound discussion needs to be addressed.

Comparison of Early vs. Delayed Anakinra Treatment in Patients With Adult Onset Still's Disease and Effect on Clinical and Laboratory Outcomes

Background: Aim of this study was to search for any difference in the outcome of patients with adult onset Still's disease (AOSD) treated with anakinra (ANK) in relation with the interval between disease onset and the start of anti-interleukin(IL)-1 treatment and according with the different lines of ANK treatment.

Patients and Methods: One hundred and forty-one AOSD patients treated with ANK have been retrospectively assessed. Statistically significant differences (p < 0.05) were analyzed in the frequency of ANK effectiveness, primary or secondary inefficacy to ANK and rate of resolution of clinical and laboratory AOSD manifestations after 3, 6, and 12 months since ANK treatment according with different lines of treatment and different times between AOSD onset and start of ANK.

Results: No significant differences were identified in the ANK effectiveness and frequency of primary or secondary inefficacy for patients starting ANK within 6 months (p = 0.19, p = 0.14, and p = 0.81, respectively) or 12 months (p = 0.37, p = 0.23, and p = 0.81, respectively) since AOSD onset compared with patients starting ANK thereafter; no significant differences were identified in ANK effectiveness and primary or secondary inefficacy according with different lines of ANK treatment (p = 0.06, p = 0.19, and p = 0.13, respectively). Patients starting ANK within 6 and 12 months since AOSD onset showed a significantly quicker decrease of erythrocyte sedimentation rate and C-reactive protein than observed among patients undergoing ANK treatment after 6 and 12 months. The number of swollen joints at the 3 month follow-up visit was significantly lower among patients undergoing ANK within 6 months since AOSD onset (p = 0.01), while no significance was identified at the 6 and 12 month assessments (p = 0.23 and p = 0.45, respectively). At the 3 and 6 month visits, the number of swollen joints was significantly higher among patients previously treated with conventional and biological disease modifying anti-rheumatic drugs (DMARDs) compared with those formerly treated only with conventional DMARDs (p < 0.017).

Conclusions: Clinical and therapeutic outcomes are substantially independent of how early ANK treatment is started in AOSD patients. However, a faster ANK effectiveness in controlling systemic inflammation and resolving articular manifestations may be observed in patients benefiting from IL-1 inhibition as soon as after disease onset.

Natural Killer Cells in Systemic Autoinflammatory Diseases: A Focus on Systemic Juvenile Idiopathic Arthritis and Macrophage Activation Syndrome

Natural killer (NK) cells are innate immune lymphocytes with potent cytolytic and immune-regulatory activities. NK cells are well-known for their ability to kill infected and malignant cells in a fast and non-specific way without prior sensitization. For this purpose, NK cells are equipped with a set of cytotoxic molecules such as perforin and apoptosis-inducing proteins. NK cells also have the capacity to produce large amounts of cytokines and chemokines that synergize with their cytotoxic function and that ensure interaction with other immune cells. A less known feature of NK cells is their capacity to kill non-infected autologous cells, such as immature dendritic cells and activated T cells and monocytes. Via the release of large amounts of TNF-α and IFN-γ, NK cells may contribute to disease pathology. Conversely they may exert a regulatory role through secretion of immuno-regulatory cytokines such as GM-CSF, IL-13, and IL-10. Thus, NK cells may be important target and effector cells in the pathogenesis of autoinflammatory diseases, in particular in those disorders associated with a cytokine storm or in conditions where immune cells are highly activated. Key examples of such diseases are systemic juvenile idiopathic arthritis (sJIA) and its well-associated complication, macrophage activation syndrome (MAS). sJIA is a chronic childhood immune disorder of unknown etiology, characterized by arthritis and systemic inflammation, including a daily spiking fever and evanescent rash. MAS is a potentially fatal complication of autoimmune and autoinflammatory diseases, and most prevalently associated with sJIA. MAS is considered as a subtype of hemophagocytic lymphohistiocytosis (HLH), a systemic hyperinflammatory disorder characterized by defective cytotoxic pathways of cytotoxic T and NK cells. In this review, we describe the established features of NK cells and provide the results of a literature survey on the reported NK cell abnormalities in monogenic and multifactorial autoinflammatory disorders. Finally, we discuss the role of NK cells in the pathogenesis of sJIA and MAS.

Regulatory Role for NK Cells in a Mouse Model of Systemic Juvenile Idiopathic Arthritis

Mice deficient in IFN-γ (IFN-γ knockout [KO] mice) develop a systemic inflammatory syndrome in response to CFA, in contrast to CFA-challenged wild-type (WT) mice who only develop a mild inflammation. Symptoms in CFA-challenged IFN-γ KO resemble systemic juvenile idiopathic arthritis (sJIA), a childhood immune disorder of unknown cause. Dysregulation of innate immune cells is considered to be important in the disease pathogenesis. In this study, we used this murine model to investigate the role of NK cells in the pathogenesis of sJIA. NK cells of CFA-challenged IFN-γ KO mice displayed an aberrant balance of activating and inhibitory NK cell receptors, lower expression of cytotoxic proteins, and a defective NK cell cytotoxicity. Depletion of NK cells (via anti-IL-2Rβ and anti-Asialo-GM1 Abs) or blockade of the NK cell activating receptor NKG2D in CFA-challenged WT mice resulted in increased severity of systemic inflammation and appearance of sJIA-like symptoms. NK cells of CFA-challenged IFN-γ KO mice and from anti-NKG2D-treated mice showed defective degranulation capacities toward autologous activated immune cells, predominantly monocytes. This is in line with the increased numbers of activated inflammatory monocytes in these mice which was particularly reflected in the expression of CCR2, a chemokine receptor, and in the expression of Rae-1, a ligand for NKG2D. In conclusion, NK cells are defective in a mouse model of sJIA and impede disease development in CFA-challenged WT mice. Our findings point toward a regulatory role for NK cells in CFA-induced systemic inflammation via a NKG2D-dependent control of activated immune cells.

[Clinical analysis of patients with hemophagocytic lymphohistiocytosis complicated with gastrointestinal bleeding]

目的

探究噬血细胞综合征（HLH）合并消化道出血患者的临床特征。

方法

对2015年1月至2017年2月确诊为HLH且合并消化道出血的52例患者的临床资料进行回顾性分析。

结果

①52例患者中，男32例（61.5%），女20例（38.5%），中位年龄为26（6~64）岁，其中EBV相关者36例（69.2%），淋巴瘤相关者5例（9.6%），原发性HLH者3例（5.8%），风湿免疫相关者3例（5.8%），结核相关者2例（3.8%），原因不明者3例（3.8%）。②52例患者的1、3、6、12个月总体生存率分别为74.7%、53.8%、32.9%和23.3%。③多因素分析（Logistic回归）结果显示血小板减少（P=0.036）、合并其他部位出血（P=0.030）是影响患者预后的不良因素，行异基因造血干细胞移植（P=0.026）是影响患者预后的良好因素。

结论

HLH合并消化道出血患者预后差。血小板减少及合并其他部位出血的患者预后不良，而异基因造血干细胞移植有助于改善患者预后。

Characteristics of Circulating Natural Killer Cells and Their Interferon-γ Production in Active Adult-onset Still Disease

Objective.

To investigate the characteristics of circulating natural killer (NK) cells and their interferon (IFN)-γ–producing ability in adult-onset Still disease (AOSD).

Methods.

Peripheral blood mononuclear cells were obtained from 22 patients in the acute phase of AOSD (acute AOSD); 7 of the 22 patients after treatment (remission AOSD), and 11 healthy controls (HC). NK cells and their IFN-γ expression levels were analyzed by flow cytometry. Additionally, the cytokine receptors of interleukin (IL)-12, IL-15, and IL-18 on NK cells were also evaluated.

Results.

The frequency of NK cells was significantly lower in acute AOSD than in HC. NK cell counts significantly increased in remission AOSD. Expression of IL-12 and IL-15 receptors on NK cells was significantly increased in acute AOSD, whereas that of IL-18 receptor indicated no significant difference among 3 groups. IFN-γ expression in NK cells was significantly higher in acute AOSD than in HC, and significantly decreased in remission AOSD. The absolute number of NK cells and IFN-γ–expressing NK cells revealed an inverse correlation with serum ferritin levels in acute AOSD. In 2 distinct subsets of NK cells, CD56dim NK cells significantly exhibited higher IFN-γ expression than CD56bright NK cells in acute AOSD.

Conclusion.

In acute AOSD, NK cells displayed lower proportion, whereas they had higher ability for IFN-γ production than in HC; moreover, upregulation of IL-12 and IL-15 receptors on NK cells may promote IFN-γ production. In addition, disease activity may be implicated in regulating the number of NK cells and IFN-γ–expressing NK cells in AOSD.

Visceral leishmaniasis with haemophagocytic lymphohistiocytosis

A 27-year-old man presented with high-grade intermittent fever for 4 months, generalised fatigue for 2 months, intermittent gum bleeds for 1 month and loss of weight of 15 kg. He appeared cachectic with generalised wasting, had pallor and features of reticuloendothelial system proliferation. His liver span was 17 cm. He had massive splenomegaly. His cardiovascular, respiratory and neurological examination were normal. He was diagnosed to have visceral leishmaniasis (VL) based on bone marrow (BM) examination that showed Leishmania donovani (LD) bodies and was treated with liposomal amphotericin (LA). During the course of therapy, he developed bleeding from various mucosal and venepuncture sites. His further evaluation, which included a repeat BM aspirate, showed haemophagocytes. Final diagnosis made was VL with secondary haemophagocytic lymphohistiocytosis. He was continued on LA with intravenous hydrocortisone. He developed refractory distributive shock with multiorgan dysfunction and succumbed to his illness.

Characteristics of bone marrow cells in 107 patients with juvenile idiopathic arthritis: A retrospective study

Few studies to date have reported on the myelodysplastic features of children with juvenile idiopathic arthritis (JIA). Bone marrow specimens were collected from 107 patients aged from 7-12 years who were initially diagnosed with JIA between May 2013 and October 2015. In 107 patients with JIA, bone marrow proliferation was higher than normal and hemophagocytes were more easily observed than usual. The characteristics of bone marrow cells in 107 patients with JIA were investigated and the associations of these characteristics with the disease was discussed in the present study. It was noticed that there were similar changes in the myeloid, erythropoietic and megakaryopoietic series in the majority of bone marrow specimens; the presence of hemophagocytes was also reported. The present findings suggest that JIA is associated with specific myelodysplastic changes, and that cellular immune system dysfunction and overreactive inflammatory cytokines may contribute to the development of these myelodysplastic changes in the bone marrow.

Human CTL-based functional analysis shows the reliability of a munc13-4 protein expression assay for FHL3 diagnosis

Familial hemophagocytic lymphohistiocytosis (FHL) is the major form of hereditary hemophagocytic lymphohistiocytosis (HLH); as such, it requires prompt and accurate diagnosis. We previously reported that FHL type 3 (FHL3) can be rapidly screened by detecting munc13-4 expression in platelets using flow cytometry; however, the reliability of the munc13-4 expression assay for FHL3 diagnosis is unclear. Regardless of the type of UNC13D mutation, all reported FHL3 cases examined for the munc13-4 protein showed significantly reduced expression. However, the translated munc13-4 protein of some reportedly disease-causing UNC13D missense variants has not been assessed in terms of expression or function; therefore, their clinical significance remains unclear. The aim of this study was to determine the reliability of a munc13-4 expression assay for screening FHL3. Between 2011 and 2016, 108 HLH patients were screened by this method in our laboratory, and all 15 FHL3 patients were diagnosed accurately. To further elucidate whether munc13-4 expression analysis can reliably identify FHL3 patients harboring missense mutations in UNC13D, we developed an alloantigen-specific cytotoxic T lymphocyte (CTL) line and a CTL line immortalized by Herpesvirus saimiri derived from FHL3 patients. We then performed a comprehensive functional analysis of UNC13D variants. Transient expression of UNC13D complementary DNA constructs in these cell lines enabled us to determine the pathogenicity of the reported UNC13D missense variants according to expression levels of their translated munc13-4 proteins. Taken together with previous findings, the results presented herein show that the munc13-4 protein expression assay is a reliable tool for FHL3 screening.

Macrophage Activation Syndrome

Hemophagocytic lymphohistiocytosis (HLH), or termed macrophage activation syndrome (MAS) when associated with rheumatic disorders, is a frequently fatal complication of infections, rheumatic disorders, and hematopoietic malignancies. Clinically, HLH/MAS is a life-threatening condition that is usually diagnosed among febrile hospitalized patients (children and adults) who commonly present with unremitting fever and a shock-like multiorgan dysfunction scenario. Laboratory studies reveal pancytopenia, elevated liver enzymes, elevated markers of inflammation (ESR, CRP), hyperferritinemia, and features of coagulopathy. In about 60% of cases, excess hemophagocytosis (macrophages/histiocytes engulfing other hematopoietic cell types) is noted on biopsy specimens from the bone marrow, liver, lymph nodes, and other organs. HLH/MAS has been hypothesized to occur when a threshold level of inflammation has been achieved, and genetic and environmental risk factors are believed to contribute to the hyperinflammatory state. A broad variety of infections, from viruses to fungi to bacteria, have been identified as triggers of HLH/MAS, either in isolation or in addition to an underlying inflammatory disease state. Certain infections, particularly by members of the herpesvirus family, are the most notorious triggers of HLH/MAS. Treatment for infection-triggered MAS requires therapy for both the underlying infection and dampening of the hyperactive immune response.

Hemophagocytic lymphohistiocytosis in an HIV-positive patient with concomitant disseminated histoplasmosis

A 46-year-old Dominican man, known to have HIV, presented with constitutional symptoms of two week's duration. The patient was found to have cytopenias, significantly elevated ferritin level and lymphadenopathy. Biopsies and laboratory studies met the criteria for hemophagocytic lymphohistiocytosis (HLH). A concomitant diagnosis of histoplasmosis was confirmed as the trigger for HLH and treatment resulted in clinical improvement and resolution of symptoms.

Lytic viral replication and immunopathology in a cytomegalovirus-induced mouse model of secondary hemophagocytic lymphohistiocytosis

Background

Hemophagocytic lymphohistiocytosis (HLH) is a rare immunological disorder caused by unbridled activation of T cells and macrophages, culminating in a life-threatening cytokine storm. A genetic and acquired subtype are distinguished, termed primary and secondary HLH, respectively. Clinical manifestations of both forms are frequently preceded by a viral infection, predominantly with herpesviruses. The exact role of the viral infection in the development of the hemophagocytic syndrome remains to be further elucidated.

Methods

We utilized a recently developed murine model of cytomegalovirus-associated secondary HLH and dissected the respective contributions of lytic viral replication and immunopathology in its pathogenesis.

Results

HLH-like disease only developed in cytomegalovirus-susceptible mouse strains unable to clear the virus, but the severity of symptoms was not correlated to the infectious viral titer. Lytic viral replication and sustained viremia played an essential part in the pathogenesis since abortive viral infection was insufficient to induce a full-blown HLH-like syndrome. Nonetheless, a limited set of symptoms, in particular anemia, thrombocytopenia and elevated levels of soluble CD25, appeared less dependent of the viral replication but rather mediated by the host’s immune response, as corroborated by immunosuppressive treatment of infected mice with dexamethasone.

Conclusion

Both virus-mediated pathology and immunopathology cooperate in the pathogenesis of full-blown virus-associated secondary HLH and are closely entangled. A certain level of viremia appears necessary to elicit the characteristic HLH-like symptoms in the model.

Pathway analysis based on Monte Carlo Cross-Validation in polyarticular juvenile idiopathic arthritis

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is a common chronic disease with onset before the 16 years old in a child. Polyarticular JIA has been reported as the main form of JIA in several locations. Until now, understanding of the genetic basis of JIA is incomplete. The purpose of this study was to identify pathway pairs of great potential functional relevance in the progression of polyarticular JIA.

MATERIALS AND METHODS

Microarray data of 59 peripheral blood samples from healthy children and 61 samples from polyarticular JIA were transformed to gene expression data. Differential expressed genes (DEG) between patients and normal controls were identified using Linear Models for Microarray Analysis. After performed enrichment of DEG, differential pathways were identified with Fisher's test and false discovery rate. Differential pathway pairs were constructed with random two differential pathways, and were evaluated by Random Forest classification. Monte Carlo Cross-Validation was introduced to screen the best pathway pair.

RESULTS

42 DEG with P-values<0.01 were identified. 19 differential pathways with P-values<0.01 were identified. Area under the curve (AUC) of pathway pairs was generated with RF classification. After 50 bootstraps of Monte Carlo Cross-Validation, the best pathway pair with the highest AUC value was identified, and it was the pair of tumoricidal function of hepatic natural killer cells pathway and erythropoietin signaling pathway.

CONCLUSION

These identified pathway pairs may play pivotal roles in the progress of polyarticular JIA and can be applied for diagnosis. Particular attention can be focused on them for further research.

Potential Effects of Interleukins on the Pathogenesis of Systemic Onset Juvenile Idiopathic Arthritis

BACKGROUND

To analyze the correlation of cytokines with clinical inflammatory indexes in systemic onset juvenile idiopathic arthritis (SOJIA).

METHODS

A total of 30 active SOJIAs, 30 remission SOJIAs, and 20 normal controls were enrolled. The clinical inflammatory indexes such as tender joints counts, swelling joints counts, C-reactive protein, erythrocyte sedimentation rate, visual analogue scale (VAS), and disease activity score 28 (DAS28) were detected. The serum cytokines interleukin (IL)-17, IL-6, IL-21, interferon (IFN)-γ, and IL-4 levels were determined with enzyme-linked immunosorbent assay method. The correlation coefficients between these cytokines and two clinical indexes (VAS and DAS28) in the active SOJIA group were calculated with the Spearman's method.

RESULTS

The serum IL-17 and IL-6 levels in active SOJIA group were significantly increased compared with those in the remission SOJIA group and control group (p < 0.05), and the serum IL-21, IFN-γ, and IL-4 levels showed no obvious difference. In the active SOJIA group, the Spearman coefficients between IL-17 and DAS28, IL-17 and IL-6, IL-6 and DAS28, and between IL-17 and VAS were 0.686 (p = 0.000), 0.833 (p = 0.000), 0.633 (p = 0.000), and 0.524 (p = 0.003), respectively. There was no correlation between cytokines of IL-21, IFN-γ, and IL-4 and the clinical indexes of DAS28 and VAS. Furthermore, in the other two groups, none of the five cytokines exhibited an association with DAS28 or VAS.

CONCLUSION

IL-6 and IL-17 were significantly correlated with DAS28 and VAS, and they might be considered as therapeutic targets for the treatment of SOJIA.

Review: Macrophage activation syndrome in juvenile systemic lupus erythematosus: an under-recognized complication?

Macrophage activation syndrome (MAS) is a life-threatening complication of rheumatic diseases that is thought to be caused by the activation and uncontrolled proliferation of T lymphocytes and macrophages, leading to widespread haemophagocytosis and cytokine overproduction. It is seen most commonly in systemic juvenile idiopathic arthritis, but is increasingly recognized also in juvenile systemic lupus erythematosus (J-SLE). Recognition of MAS in patients with J-SLE is often challenging because it may mimic the clinical features of the underlying disease or be confused with an infectious complication. This review summarizes the characteristics of patients with J-SLEassociated MAS reported in the literature or seen by the authors and analyses the distinctive clinical, diagnostic and therapeutic issues that the occurrence of MAS may raise in patients with J-SLE. Lupus (2007) 16, 587—592.

Understanding the spectrum of haemophagocytic lymphohistiocytosis: update on diagnostic challenges and therapeutic options

The cytokine storm syndrome 'haemophagocytic lymphohistiocytosis' (HLH) is an under-recognized hyperinflammatory disorder, causing high morbidity and mortality risk in children and adults. It can be subdivided into a primary, genetic form and a secondary, acquired form that complicates diverse infections, malignancies and autoimmune or autoinflammatory disorders. Both subtypes present with the same spectrum of non-specific symptoms, making accurate diagnosis and rapid treatment initiation challenging. In the last decade, increased awareness and international collaborative efforts fuelled a marked progress in diagnostic protocols and novel treatment strategies for HLH and new diagnostic guidelines are being tailored to specific secondary HLH subtypes. Therapy is gradually shifting its focus from overall immunosuppression towards targeting specific cytokines, cell types or signalling pathways underlying pathophysiology. Nevertheless, continued research efforts remain indispensable to customize therapy to individual patient needs.

Advances in the pathogenesis of primary and secondary haemophagocytic lymphohistiocytosis: differences and similarities

Haemophagocytic lymphohistiocytosis (HLH) comprises a heterogeneous spectrum of hyperinflammatory conditions that are inherited (primary HLH) or acquired in a context of infections, malignancies or autoimmune/autoinflammatory disorders (secondary HLH). Genetic defects in the cytotoxic machinery of natural killer and CD8(+) T cells underlie primary HLH, with residual cytotoxicity determining disease severity. Improved sequencing techniques have expanded the range of causal mutations and have redefined many cases of secondary HLH as primary HLH and vice versa, blurring the distinction between both subtypes. These insights allow HLH to be conceptualized as a threshold disease, in which interplay between various genetic and environmental factors causes progressive inflammation into a critical point, beyond which uncontrolled activation of immune cells and excessive cytokine production give rise to the cardinal symptoms of HLH. Various pathogenic pathways may thus converge to a common end stage of fulminant HLH.

Rate and Clinical Presentation of Macrophage Activation Syndrome in Patients With Systemic Juvenile Idiopathic Arthritis Treated With Canakinumab

OBJECTIVE

In pivotal trials, canakinumab has been shown to be effective in the treatment of systemic juvenile idiopathic arthritis (JIA), but reported adverse events have included macrophage activation syndrome (MAS). This study was undertaken to assess the impact of canakinumab on MAS incidence.

METHODS

An independent MAS Adjudication Committee (MASAC), consisting of 3 of the authors, was convened, and a search of databases from clinical studies of canakinumab treatment in systemic JIA was performed using MASAC-specified adverse event terms to identify potential MAS events. These were then adjudicated as "probable MAS," "possible MAS," or "MAS unlikely," using criteria developed by the MASAC. MAS rates were expressed as numbers of cases per 100 patient-years.

RESULTS

Of 72 potential MAS cases identified, 21 events (19 with canakinumab treatment; 2 with placebo treatment) in 19 patients were adjudicated as being probable MAS and 10 events in 9 patients as being possible MAS. Systemic JIA was well controlled in the majority of canakinumab-treated patients at the time of MAS. The time period between initiation of canakinumab treatment and onset of MAS ranged from 3 to 1,358 days (median 292 days). When the rates of probable MAS events were compared between canakinumab-treated patients (2.8 per 100 patient-years) and placebo-treated patients (7.7 per 100 patient-years), the difference was not significant (-4.9 [95% confidence interval -15.6, 5.9]). There were 3 deaths due to MAS-related complications (2 in patients receiving canakinumab; 1 in a patient receiving placebo); full recovery was reported in all other patients. Infections were the most common trigger of MAS, and the clinical features of MAS were not modified by canakinumab.

CONCLUSION

Canakinumab does not have a significant effect on MAS risk or its clinical features in patients with systemic JIA. Infections are the most common trigger, and MAS occurs even in patients whose systemic JIA is well controlled with this treatment.

Mouse Cytomegalovirus Infection in BALB/c Mice Resembles Virus-Associated Secondary Hemophagocytic Lymphohistiocytosis and Shows a Pathogenesis Distinct from Primary Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening immunological disorder that is characterized by systemic inflammation, widespread organ damage, and hypercytokinemia. Primary HLH is caused by mutations in granule-mediated cytotoxicity, whereas secondary HLH occurs, without a known genetic background, in a context of infections, malignancies, or autoimmune and autoinflammatory disorders. Clinical manifestations of both HLH subtypes are often precipitated by a viral infection, predominantly with Herpesviridae. Exploiting this knowledge, we established an animal model of virus-associated secondary HLH by infecting immunocompetent wild-type mice with the β-herpesvirus murine CMV. C57BL/6 mice developed a mild inflammatory phenotype, whereas BALB/c mice displayed the clinicopathologic features of HLH, as set forth in the Histiocyte Society diagnostic guidelines: fever, cytopenia, hemophagocytosis, hyperferritinemia, and elevated serum levels of soluble CD25. BALB/c mice also developed lymphadenopathy, liver dysfunction, and decreased NK cell numbers. Lymphoid and myeloid cells were in a hyperactivated state. Nonetheless, depletion of CD8(+) T cells could not inhibit or cure the HLH-like syndrome, highlighting a first dissimilarity from mouse models of primary HLH. Immune cell hyperactivation in BALB/c mice was accompanied by a cytokine storm. Notably, plasma levels of IFN-γ, a key pathogenic cytokine in models of primary HLH, were the highest. Nevertheless, murine CMV-infected IFN-γ-deficient mice still developed the aforementioned HLH-like symptoms. In fact, IFN-γ-deficient mice displayed a more complete spectrum of HLH, including splenomegaly, coagulopathy, and decreased NK cell cytotoxicity, indicating a regulatory role for IFN-γ in the pathogenesis of virus-associated secondary HLH as opposed to its central pathogenic role in primary HLH.

Inhibition of natural killer cell cytotoxicity by interleukin-6: implications for the pathogenesis of macrophage activation syndrome

OBJECTIVE

Systemic juvenile idiopathic arthritis (JIA) is associated with high levels of interleukin-6 (IL-6) in the serum and synovial fluid, and impairment of natural killer (NK) cell function is often observed. This study was undertaken to evaluate a possible link between these 2 biologic findings and whether they may be associated with the development of macrophage activation syndrome, a condition frequently observed in systemic JIA.

METHODS

Splenocytes from wild-type (WT) or IL-6-transgenic (Tg) mice were evaluated for NK cell cytotoxicity using a (51) Cr-release assay. Numbers of NK cells and expression of perforin, granzyme B, CD69, and CD107a were evaluated by flow cytometry. Human peripheral blood mononuclear cells (PBMCs) isolated from healthy donors were treated with IL-6 and cultured in the presence or absence of tocilizumab (TCZ), an IL-6 receptor blocker. Human polyclonal NK cells from healthy donor PBMCs were evaluated for cell cytotoxicity and expression of perforin, granzyme B, and CD107a. PBMCs harvested from patients with systemic JIA during periods of active or inactive disease were left untreated or treated with IL-6 in combination with soluble IL-6 receptor and analyzed for the expression of perforin and granzyme B.

RESULTS

Splenic NK cell cytotoxicity was reduced in IL-6-Tg mice compared to WT mice. Levels of CD69 and CD107a showed no significant differences, whereas expression of perforin and granzyme B was impaired in NK cells from IL-6-Tg mice. Exposure of human peripheral blood NK cells to IL-6 led to reduced expression of perforin and granzyme B. Culturing human polyclonal NK cells in the presence of TCZ significantly increased cell cytotoxicity, and also increased expression of perforin and granzyme B. In patients with systemic JIA, a reduction in IL-6 plasma levels during disease remission correlated with the rescue of perforin and granzyme B expression in NK cells from these patients.

CONCLUSION

In both mice and humans, IL-6 down-modulated the cytotoxic activity of NK cells. This decrease was associated with reduced perforin and granzyme B levels in the absence of altered granule exocytosis.

The role of natural killer cells in pathogenesis of autoimmune diseases

There is growing evidence that NK cell-mediated immunoregulation plays an important role in the control of autoimmunity. NK cells are a subset of lymphocytes that generally contribute to innate immunity but have also a great impact on the function of T and B lymphocytes. The major role of NK cells is cytotoxic reaction against neoplastic, infected and autoreactive cells, but they regulatory function seems to play more important role in the pathogenesis of autoimmune diseases. Numerous studies suggested the involvement of NK cells in pathogenesis of such a common autoimmune diseases as juvenile rheumatoid arthritis, type I diabetes and autoimmune thyroid diseases. The defects of NK cells regulatory function as well as cytotoxic abilities are common in patients with autoimmune diseases with serious consequences including HLH hemophagocytic lymphocytosis (HLH) and macrophage activation syndrome (MAS). The early diagnosis of NK cells defect responsible for the loss of the protective abilities is crucial for the prevention of life-threatening complications and implementation of necessary treatment.

Cytosine-Phosphorothionate-Guanine Oligodeoxynucleotides Exacerbates Hemophagocytosis by Inducing Tumor Necrosis Factor-Alpha Production in Mice after Bone Marrow Transplantation

Hemophagocytic syndrome (HPS) is frequently associated with hematopoietic stem cell transplantation and is treated with some benefit derived from TNF-α inhibitors. However, the mechanisms of how HPS occurs and how a TNF-α inhibitor exerts some benefit to HPS management have remained unclear. We evaluated the effect of toll-like receptor (TLR) ligands, especially focusing on cytosine-phosphorothionate-guanine oligodeoxynucleotide (CpG), a TLR9 ligand, on HPS in mice that underwent transplantation with syngeneic or allogeneic bone marrow (BM) cells (Syn-BMT, Allo-BMT), or with allogeneic BM cells plus splenocytes to promote graft-versus-host disease (GVHD mice). Hemophagocytosis was a common feature early after all BMT, but it subsided in Syn-BMT and Allo-BMT mice. In GVHD mice, however, hemophagocytosis persisted and was accompanied by upregulated production of IFN-γ but not TNF-α, and it was suppressed by blockade of IFN-γ but not TNF-α. A single injection of the TLR9 ligand CpG promoted HPS in all BMT mice and was lethal in GVHD mice, accompanied by greatly upregulated production of TNF-α, IL-6, and IFN-γ. Blocking of TNF-α, but not IL-6 or IFN-γ, suppressed CpG-induced HPS in all BMT mice and rescued GVHD mice from CpG-induced mortality. Thus, TLR9 signaling mediates TNF-α-driven HPS in BMT mice and is effectively treated through TNF-α inhibition.

Therapeutic Potential of Interferon-γ and Its Antagonists in Autoinflammation: Lessons from Murine Models of Systemic Juvenile Idiopathic Arthritis and Macrophage Activation Syndrome

Interferon-γ (IFN-γ) affects immune responses in a complex fashion. Its immunostimulatory actions, such as macrophage activation and induction of T helper 1-type responsiveness, are widely acknowledged, however, as documented by a large body of literature, IFN-γ has also the potential to temper inflammatory processes via other pathways. In autoimmune and autoinflammatory disorders, IFN-γ can either play a disease-enforcing role or act as protective agent, depending on the nature of the disease. In animal models of any particular autoimmune disease, certain changes in the induction procedure can reverse the net outcome of introduction or ablation of IFN-γ. Here, we review the role of endogenous IFN-γ in inflammatory disorders and related murine models, with a focus on systemic juvenile idiopathic arthritis (sJIA) and macrophage activation syndrome (MAS). In particular, we discuss our recent findings in a mouse model of sJIA, in which endogenous IFN-γ acts as a regulatory agent, and compare with results from mouse models of MAS. Also, we elaborate on the complexity in the activity of IFN-γ and the resulting difficulty of predicting its value or that of its antagonists as treatment option.

Macrophage Activation Syndrome

Macrophage activation syndrome (MAS) is a potentially life-threatening complication of rheumatic disorders that occurs most commonly in systemic juvenile idiopathic arthritis. In recent years, there have been several advances in the understanding of the pathophysiology of MAS. Furthermore, new classification criteria have been developed. Although the place of cytokine blockers in the management of MAS is still unclear, interleukin-1 inhibitors represent a promising adjunctive therapy, particularly in refractory cases.