Expansion of CD4dimCD8+ T cells characterizes macrophage activation syndrome and other secondary HLH.

CD8+ T-cell activation has been demonstrated to distinguish patients with primary and infection-associated hemophagocytic lymphohistiocytosis (HLH) from patients with early sepsis. We evaluated the activation profile of CD8+ T cells in patients with various forms of secondary HLH (sHLH), including macrophage activation syndrome (MAS). Peripheral blood mononuclear cells from children with inactive systemic juvenile idiopathic arthritis (sJIA, n = 17), active sJIA (n = 27), MAS in sJIA (n = 14), infection-associated HLH (n = 7), and with other forms of sHLH (n = 9) were analyzed by flow cytometry. Compared with patients with active sJIA, in patients with MAS and sHLH of different origins, beside a significant increase in the frequency of CD38high/HLA-DR+CD8+ T cells, we found a significant increase in the frequency of CD8+ T cells expressing the CD4 antigen (CD4dimCD8+ T cells). These cells expressed high levels of the activation markers CD38 and HLA-DR, suggesting they were a subset of CD38high/HLA-DR+CD8+ T cells, as well as of the activation/exhaustion markers CD25, PD1, CD95, and interferon-γ. The frequency of CD4dimCD8+ T cells strongly correlated with most of the laboratory parameters of MAS severity and with circulating levels of CXCL9 and interleukin-18. These findings were confirmed in a prospective replication cohort in which no expansion of any particular T-cell receptor Vß family in CD3+ T cells of patients with sHLH was found. Finally, frequency of CD4dimCD8+, but not of CD38high/HLA-DR+CD8+ T cells, significantly correlated with a clinical severity score, further supporting the involvement of these cells in MAS/sHLH pathogenesis.

Laboratory Features and Pathology of Cytokine Storm Syndromes.

The laboratory diagnosis of cytokine storm syndromes (CSSs), i.e., hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS), is often challenging. The laboratory features using routinely available tests lack specificity, whereas confirmatory testing is available in only few laboratories in the United States. The disease mechanisms are still largely unclear, particularly in adults. In this chapter, the pathogenesis of CSSs, their associated laboratory findings, and recommended diagnostic strategies are reviewed.

Cytokine storm in severe COVID-19 pneumonia.

In this study, laboratorial parameters of hospitalized novel coronavirus (COVID-19) patients, who were complicated with severe pneumonia, were compared with the findings of cytokine storm developing in macrophage activation syndrome (MAS)/secondary hemophagocytic lymphohistiocytosis (sHLH). Severe pneumonia occurred as a result of cytokine storm in some patients who needed intensive care unit (ICU), and it is aimed to determine the precursive parameters in this situation. Also in this study, the aim is to identify laboratory criteria that predict worsening disease and ICU intensification, as well as the development of cytokine storm. This article comprises a retrospective cohort study of patients admitted to a single institution with COVID-19 pneumonia. This study includes 150 confirmed COVID-19 patients with severe pneumonia. When they were considered as severe pneumonia patients, the clinic and laboratory parameters of this group are compared with H-score criteria. Patients are divided into two subgroups; patients with worsened symptoms who were transferred into tertiary ICU, and patients with stable symptoms followed in the clinic. For the patients with confirmed COVID-19 infection, after they become complicated with severe pneumonia, lymphocytopenia (55.3%), anemia (12.0%), thrombocytopenia (19.3%), hyperferritinemia (72.5%), hyperfibrinogenemia (63.7%) and elevated lactate dehydrogenase (LDH) (90.8%), aspartate aminotransaminase (AST) (31.3%), alanine aminotransaminase (ALT) (20.7%) are detected. There were no significant changes in other parameters. Blood parameters between the pre-ICU period and the ICU period (in which their situation had been worsened and acute respiratory distress syndrome [ARDS] was developed) were also compared. In the latter group lymphocyte levels were found significantly reduced (p = 0.01), and LDH, highly sensitive troponin (hs-troponin), procalcitonin, and triglyceride levels were significantly increased (p < 0.05). In addition, there was no change in hemoglobin, leukocyte, platelet, ferritin, and liver function test levels, including patients who developed ARDS, similar to the cytokine storm developed in MAS/sHLH. COVID-19 pneumonia has similar findings as hyperinflammatory syndromes but does not seem to have typical features as in cytokine storm developed in MAS/sHLH. In the severe patient group who has started to develop ARDS signs, a decrease in lymphocyte level in addition to the elevated LDH, hs-troponin, procalcitonin, and triglyceride levels can be a predictor in progression to ICU admission and could help in the planning of anti-cytokine therapy.

Diffuse interstitial pneumonia-like/macrophage activation syndrome-like changes in patients with COVID-19 correlate with length of illness.

OBJECTIVES: Assess the pathologic changes in the lungs of COVID-19 decedents and correlate these changes with demographic data, clinical course, therapies, and duration of illness. METHODS: Lungs of 12 consecutive COVID-19 decedents consented for autopsy were evaluated for gross and histopathologic abnormalities. A complete Ghon "en block" dissection was performed on all cases; lung weights and gross characteristics recorded. Immunohistochemical studies were performed to characterize lymphocytic infiltrates and to assess SARS-CoV-2 capsid protein. RESULTS: Two distinct patterns of pulmonary involvement were identified. Three of 12 cases demonstrated a predominance of acute alveolar damage (DAD) while 9 of 12 cases demonstrated a marked increase in intra-alveolar macrophages in a fashion resembling desquamative interstitial pneumonia or macrophage activation syndrome (DIP/MAS). Two patterns were correlated solely with a statistically significant difference in the duration of illness. The group exhibiting DAD had duration of illness of 5.7 days while the group with DIP/MAS had duration of illness of 21.5 days (t-test p = 0.014). CONCLUSIONS: The pulmonary pathology of COVID-19 patients demonstrates a biphasic pattern, an acute phase demonstrating DAD changes while the patients with a more prolonged course exhibit a different pattern that resembles DIP/MAS-like pattern. The potential mechanisms and clinical significance are discussed.

Lung involvement in macrophage activation syndrome and severe COVID-19: results from a cross-sectional study to assess clinical, laboratory and artificial intelligence-radiological differences.

OBJECTIVES: To evaluate the clinical pictures, laboratory tests and imaging of patients with lung involvement, either from severe COVID-19 or macrophage activation syndrome (MAS), in order to assess how similar these two diseases are. METHODS: The present work has been designed as a cross-sectional single-centre study to compare characteristics of patients with lung involvement either from MAS or severe COVID-19. Chest CT scans were assessed by using an artificial intelligence (AI)-based software. RESULTS: Ten patients with MAS and 47 patients with severe COVID-19 with lung involvement were assessed. Although all patients showed fever and dyspnoea, patients with MAS were characterised by thrombocytopaenia, whereas patients with severe COVID-19 were characterised by lymphopaenia and neutrophilia. Higher values of H-score characterised patients with MAS when compared with severe COVID-19. AI-reconstructed images of chest CT scan showed that apical, basal, peripheral and bilateral distributions of ground-glass opacities (GGOs), as well as apical consolidations, were more represented in severe COVID-19 than in MAS. C reactive protein directly correlated with GGOs extension in both diseases. Furthermore, lymphopaenia inversely correlated with GGOs extension in severe COVID-19. CONCLUSIONS: Our data could suggest laboratory and radiological differences between MAS and severe COVID-19, paving the way for further hypotheses to be investigated in future confirmatory studies.

Unopposed IL-18 signaling leads to severe TLR9-induced macrophage activation syndrome in mice.

The term macrophage activation syndrome (MAS) defines a severe, potentially fatal disorder characterized by overwhelming inflammation and multiorgan involvement. Interleukin-18 (IL-18) is a proinflammatory cytokine belonging to the IL-1 family, the activity of which is regulated by its endogenous inhibitor IL-18 binding protein (IL-18BP). Elevated IL-18 levels have been reported in patients with MAS. Herein, we show that on repeated toll-like receptor 9 (TLR9) stimulation with unmethylated cytosine guanine dinucleotide containing single-stranded DNA (CpG), IL-18BP-/- mice display severe MAS manifestations, including increased weight loss, splenomegaly, anemia, thrombocytopenia, hyperferritinemia, and bone marrow hemophagocytosis as compared with wild-type mice. Serum-free IL-18 was detected in CpG-treated IL-18BP-/- mice only. Levels of interferon-γ (IFN-γ) and of IFN-γ signature genes, such as the chemokine Cxcl9 or the transcription factor CIIta, were significantly increased in IL-18BP-/- mice. Blocking IL-18 receptor signaling attenuated the severity of MAS and IFN-γ responses in IL-18BP-/- mice. Blocking IFN-γ had comparable effects to IL-18 inhibition on most MAS manifestations. Our data indicate that endogenous IL-18BP exerts a protective role in CpG-induced MAS and that IL-18, which acts upstream of IFN-γ, is involved in the severity of MAS.

Interleukin-18 diagnostically distinguishes and pathogenically promotes human and murine macrophage activation syndrome.

Hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening hyperferritinemic systemic inflammatory disorders. Although profound cytotoxic impairment causes familial HLH (fHLH), the mechanisms driving non-fHLH and MAS are largely unknown. MAS occurs in patients with suspected rheumatic disease, but the mechanistic basis for its distinction is unclear. Recently, a syndrome of recurrent MAS with infantile enterocolitis caused by NLRC4 inflammasome hyperactivity highlighted the potential importance of interleukin-18 (IL-18). We tested this association in hyperferritinemic and autoinflammatory patients and found a dramatic correlation of MAS risk with chronic (sometimes lifelong) elevation of mature IL-18, particularly with IL-18 unbound by IL-18 binding protein, or free IL-18. In a mouse engineered to carry a disease-causing germ line NLRC4T337S mutation, we observed inflammasome-dependent, chronic IL-18 elevation. Surprisingly, this NLRC4T337S-induced systemic IL-18 elevation derived entirely from intestinal epithelia. NLRC4T337S intestines were histologically normal but showed increased epithelial turnover and upregulation of interferon-γ-induced genes. Assessing cellular and tissue expression, classical inflammasome components such as Il1b, Nlrp3, and Mefv predominated in neutrophils, whereas Nlrc4 and Il18 were distinctly epithelial. Demonstrating the importance of free IL-18, Il18 transgenic mice exhibited free IL-18 elevation and more severe experimental MAS. NLRC4T337S mice, whose free IL-18 levels were normal, did not. Thus, we describe a unique connection between MAS risk and chronic IL-18, identify epithelial inflammasome hyperactivity as a potential source, and demonstrate the pathogenicity of free IL-18. These data suggest an IL-18-driven pathway, complementary to the cytotoxic impairment of fHLH, with potential as a distinguishing biomarker and therapeutic target in MAS.

The frequency of macrophage activation syndrome and disease course in systemic juvenile idiopathic arthritis.

Objectives: The aim of this study was to demonstrate the frequency of macrophage activation syndrome (MAS) in systemic juvenile idiopathic arthritis (sJIA) cases, to compare the laboratory tests at the time of diagnosis of sJIA and MAS and to see whether sJIA cases complicated with MAS follow a more severe disease course in the long-term follow-up.Methods: Files of children with sJIA that were followed between May 2010 and September 2017 were reviewed.Results: The cohort consisted of 53 sJIA cases. Mean duration of follow-up was 39.0 ± 24.1 months. The frequency of MAS was 33.9%. Initial laboratory tests at the time of diagnosis of sJIA were compared in between patients with MAS and without MAS. Only ferritin and fibrinogen levels showed significant differences in between the groups (p < .01). Patients who developed MAS had higher ferritin (4482 mg/dL) and lower fibrinogen (371 mg/dL) values than patients without MAS (ferritin 2060 mg/dL, fibrinogen 466 mg/dL) at the time of diagnosis of sJIA. Long-term follow-up results showed that monocyclic course was observed in 45.2%, polycyclic course in 30.1% and persistent course in 24.5% of the cases. It was seen that patients with MAS segregated equally into three groups.Conclusions: Higher ferritin and relatively lower fibrinogen levels at the time of diagnosis of sJIA may be early warning signs of an impending MAS. sJIA patients who develop MAS do not seem to warrant more guarded prognosis in the long-term follow-up.

Plcγ2/Tmem178 dependent pathway in myeloid cells modulates the pathogenesis of cytokine storm syndrome.

Cytokine storm syndrome (CSS) is a life-threatening condition characterized by excessive activation of T cells and uncontrolled inflammation, mostly described in patients with familial hemophagocytic lymphohistiocytosis and certain systemic auto-inflammatory diseases, such as systemic juvenile idiopathic arthritis (sJIA). Defects in T cell cytotoxicity as a mechanism for uncontrolled inflammation following viral infections fail to represent the whole spectrum of CSS. Evidence implicates dysregulated innate immune responses, especially activation of monocytes and macrophages, in patients with CSS. However, the direct contribution of monocytes/macrophages to CSS development and the signaling pathways involved in their activation have not been formally investigated. We find that depletion of monocytes/macrophages during early stages of CSS development, by clodronate-liposomes or neutralizing anti-CSF1 antibody, reduces mortality and inflammatory cytokine levels in two CSS mouse models, one dependent on T cells and the second induced by repeated TLR9 stimulation. We further demonstrate that activation of Plcγ2 in myeloid cells controls CSS development by driving macrophage pro-inflammatory responses. Intriguingly, the Plcγ2 downstream effector Tmem178, a negative modulator of calcium levels, acts in a negative feedback loop to restrain inflammatory cytokine production. Genetic deletion of Tmem178 leads to pro-inflammatory macrophage polarization in vitro and more severe CSS in vivo. Importantly, Tmem178 levels are reduced in macrophages from mice with CSS and after exposure to plasma from sJIA patients with active disease. Our data identify a novel Plcγ2/Tmem178 axis as a modulator of inflammatory cytokine production by monocytes/macrophages. We also find that loss of Tmem178 accentuates the pro-inflammatory responses in CSS.

Pharmacological targeting of plasmin prevents lethality in a murine model of macrophage activation syndrome.

Macrophage activation syndrome (MAS) is a life-threatening disorder characterized by a cytokine storm and multiorgan dysfunction due to excessive immune activation. Although abnormalities of coagulation and fibrinolysis are major components of MAS, the role of the fibrinolytic system and its key player, plasmin, in the development of MAS remains to be solved. We established a murine model of fulminant MAS by repeated injections of Toll-like receptor-9 (TLR-9) agonist and d-galactosamine (DG) in immunocompetent mice. We found plasmin was excessively activated during the progression of fulminant MAS in mice. Genetic and pharmacological inhibition of plasmin counteracted MAS-associated lethality and other related symptoms. We show that plasmin regulates the influx of inflammatory cells and the production of inflammatory cytokines/chemokines. Collectively, our findings identify plasmin as a decisive checkpoint in the inflammatory response during MAS and a potential novel therapeutic target for MAS.

Refractory macrophage activation syndrome in the setting of adult-onset Still disease with hemophagocytic lymphohistiocytosis detected on skin biopsy treated with canakinumab and tacrolimus.

A 19-year-old Caucasian female with adult-onset Still disease (AOSD) presented for evaluation of an acute clinical decompensation and atypical annular papules and plaques with purpura on the lower extremities. A punch biopsy demonstrated histiocytes with engulfed degenerated erythrocytes and lymphocytes, consistent with hemophagocytic lymphohistiocytosis (HLH). HLH, clinically referred to as macrophage activation syndrome, is a rare complication of AOSD and is life-threatening. Relevant clinical, laboratory, and histologic features of this diagnosis are reviewed.

Primary varicella infection in children with systemic juvenile idiopathic arthritis under tocilizumab therapy.

We report the clinical course and outcome of primary varicella infection in six children with systemic juvenile idiopathic arthritis (sJIA) receiving tocilizumab. None had disseminated or fatal varicella infection, but one patient developed macrophage activation syndrome (MAS) and another had an arthritis relapse. All patients had a significant elevation of serum IL-6 levels, and the two children who developed MAS or arthritis relapse showed high serum IL-18 levels, which could cause a sJIA flare-up.

Macrophage activation-like syndrome: an immunological entity associated with rapid progression to death in sepsis.

BACKGROUND: A subanalysis of a randomized clinical trial indicated sepsis survival benefit from interleukin (IL)-1 blockade in patients with features of the macrophage activation-like syndrome (MALS). This study aimed to investigate the frequency of MALS and to develop a biomarker of diagnosis and prognosis. METHODS: Patients with infections and systemic inflammatory response syndrome were assigned to one test cohort (n = 3417) and a validation cohort (n = 1704). MALS was diagnosed for patients scoring positive either for the hemophagocytic syndrome score and/or having both hepatobiliary dysfunction and disseminated intravascular coagulation. Logistic regression analysis was used to estimate the predictive value of MALS for 10-day mortality in both cohorts. Ferritin, sCD163, IL-6, IL-10, IL-18, interferon gamma (IFN-γ), and tumor necrosis factor alpha (TNF-α) were measured in the blood the first 24 h; ferritin measurements were repeated in 747 patients on day 3. RESULTS: The frequency of MALS was 3.7% and 4.3% in the test and the validation cohort, respectively. In both cohorts, MALS was an independent risk factor for 10-day mortality. A ferritin level above 4420 ng/ml was accompanied by 66.7% and 66% mortality after 28 days, respectively. Ferritin levels above 4420 ng/ml were associated with an increase of IL-6, IL-18, INF-γ, and sCD163 and a decreased IL-10/TNF-α ratio, indicating predominance of pro-inflammatory phenomena. Any less than 15% decrease of ferritin on day 3 was associated with more than 90% sensitivity for unfavorable outcome after 10 days. This high mortality risk was also validated in an independent Swedish cohort (n = 109). CONCLUSIONS: MALS is an independent life-threatening entity in sepsis. Ferritin measurements can provide early diagnosis of MALS and may allow for specific treatment.

Kawasaki Disease Complicated With Macrophage Activation Syndrome: A Systematic Review.

Macrophage activation syndrome (MAS), also known as secondary hemophagocytic lymphohistiocytosis, is a rare and potentially fatal complication of Kawasaki disease (KD). We report 2 cases, performed a literature search, and analyze the characteristics of MAS associated with KD. A total of 69 patients were evaluated, 34 reported the date of the diagnosis of MAS and KD, 6% had a diagnosis of MAS before KD, 21% had a simultaneous presentation, and 73% had the diagnosis of MAS after KD. Different treatment approaches were observed with corticosteroids administered in 87%, cyclosporine in 49%, etoposide (VP-16) in 39%, and monoclonal anti-TNF in 6% of cases. Coronary abnormalities were especially high in this group of patients (46%) and 9 patients died (13%). The persistence of fever with splenomegaly, hyperferritinemia, thrombocytopenia, and elevated aspartate aminotransferase (AST) should prompt the consideration of MAS complicating KD.

Macrophage Activation Syndrome.

Macrophage Activation Syndrome (MAS) occurs as a severe life-threatening complication of several chronic rheumatic diseases. It is more frequent with systemic onset juvenile arthritis and adult onset Still's disease.1 It can be primary, infection related, malignancy associated or autoimmune3. We report a case of Macrophage Activation Syndrome presenting as pyrexia of unknown origin (PUO) and pancytopenia in the absence of any known triggering factor.

Erythematosus plaques with macrophage infiltration as an initial manifestation of macrophage activation syndrome in a patient with systemic lupus erythematosus.

The diagnosis of macrophage activation syndrome (MAS) in patients with systemic lupus erythematosus (SLE) may be challenging as it can mimic the clinical features of the underlying disease or be confused with an infectious complication. In this report, a Japanese woman in her forties had diverse clinical features of MAS at initial presentation of SLE, where erythematosus plaques with histiocytic infiltrates focally surrounding degenerated collagen might be the earliest indicator of MAS.

Cytokines in systemic juvenile idiopathic arthritis and haemophagocytic lymphohistiocytosis: tipping the balance between interleukin-18 and interferon-γ.

OBJECTIVES: To study the role of IFN-γ in the pathogenesis of systemic JIA (sJIA) and haemophagocytic lymphohistiocytosis (HLH) by searching for an IFN-γ profile, and to assess its relationship with other cytokines. METHODS: Patients with inactive (n = 10) and active sJIA (n = 10), HLH [n = 5; of which 3 had sJIA-associated macrophage activation syndrome (MAS)] and healthy controls (n = 16) were enrolled in the study. Cytokines and IFN-γ-induced genes and proteins were determined in plasma, in patient peripheral blood mononuclear cells (PBMCs) and in lymph node biopsies of one patient during both sJIA and MAS episodes. IFN-γ responses were investigated in healthy donor PBMCs, primary fibroblasts and endothelial cells. RESULTS: Plasma IFN-γ, IL-6 and IL-18 were elevated in active sJIA and HLH. Levels of IFN-γ and IFN-γ-induced proteins (IP-10/CXCL-10, IL-18BP and indoleamine 2,3-dioxygenase) in HLH were much higher than levels in active sJIA. Free IL-18 and ratios of IL-18/IFN-γ were higher in active sJIA compared with HLH. HLH PBMCs showed hyporesponsiveness to IFN-γ in vitro when compared with control and sJIA PBMCs. Endothelial cells and fibroblasts expressed IFN-γ-induced proteins in situ in lymph node staining of a MAS patient and in vitro upon stimulation with IFN-γ. CONCLUSION: Patients with active sJIA and HLH/MAS show distinct cytokine profiles, with highly elevated plasma levels of IFN-γ and IFN-γ-induced proteins typically found in HLH/MAS. In addition to PBMCs, histiocytes, endothelial cells and fibroblasts may contribute to an IFN-γ profile in plasma. Increasing levels of IFN-γ compared with IL-18 may raise suspicion about the development of MAS in sJIA.

A case of macrophage activation syndrome developing in a patient with chronic granulomatous disease-associated colitis.

Although macrophage activation syndrome (MAS) develops in some patients with chronic granulomatous disease (CGD), all of the reported cases have been associated with pathogenic microbial infections. We report a 2-year-old boy with CGD-associated colitis who suffered from MAS without any clinical signs of a microbial infection. He was treated with 1 course of methylprednisolone pulse therapy and the clinical symptoms improved; however, the colitis was difficult to control even with immunosuppressive drugs, and he eventually required hematopoietic stem cell transplantation 1 year after the onset of MAS. It is likely that MAS develops in patients with CGD colitis independent of microbial infections.

The NLRP3 inflammasome is essential for IL-18 production in a murine model of macrophage activation syndrome.

Hyperinflammatory disease is associated with an aberrant immune response resulting in cytokine storm. One such instance of hyperinflammatory disease is known as macrophage activation syndrome (MAS). The pathology of MAS can be characterised by significantly elevated serum levels of interleukin-18 (IL-18) and interferon gamma (IFNγ). Given the role for IL-18 in MAS, we sought to establish the role of inflammasomes in the disease process. Using a murine model of CpG-oligonucleotide-induced MAS, we discovered that the expression of the NLRP3 inflammasome was increased and correlated with IL-18 production. Inhibition of the NLRP3 inflammasome or the downstream caspase-1 prevented MAS-mediated upregulation of IL-18 in the plasma but, interestingly, did not alleviate key features of hyperinflammatory disease including hyperferritinaemia and splenomegaly. Furthermore blockade of IL-1 receptor with its antagonist IL-1Ra did not prevent the development of CpG-induced MAS, despite being clinically effective in the treatment of MAS. These data demonstrate that, during the development of MAS, the NLRP3 inflammasome was essential for the elevation in plasma IL-18 - a key cytokine in clinical cases of MAS - but was not a driving factor in the pathogenesis of CpG-induced MAS.