Internalisation of neutrophils extracellular traps by macrophages aggravate rheumatoid arthritis via Rab5a

OBJECTIVES

Although elevated levels of neutrophil extracellular traps (NETs) have been reported in patients with rheumatoid arthritis (RA), the role of NETs in RA and the relationship between NETs and macrophages in the pathogenesis of RA requires further research. Here, we sought to determine the role of NETs in RA pathogenesis and reveal the potential mechanism.

METHODS

Neutrophil elastase (NE) and myeloperoxidase (MPO)-DNA were measured in human serum and synovium. NETs inhibitor GSK484 was used to examine whether NETs involved with RA progression. We stimulated macrophages with NETs and detected internalisation-related proteins to investigate whether NETs entry into macrophages and induced inflammatory cytokines secretion through internalisation. To reveal mechanisms mediating NETs-induced inflammation aggravation, we silenced GTPases involved in internalisation and inflammatory pathways in vivo and in vitro and detected downstream inflammatory pathways.

RESULTS

Serum and synovium from patients with RA showed a significant increase in NE and MPO, which positively correlated to disease activity. Inhibiting NETs formation alleviated the collagen-induced arthritis severity. In vitro, NETs are internalised by macrophages and located in early endosomes. Rab 5a was identified as the key mediator of the NETs internalisation and inflammatory cytokines secretion. Rab 5a knockout mice exhibited arthritis alleviation. Moreover, we found that NE contained in NETs activated the Rab5a-nuclear factor kappa B (NF-κB) signal pathway and promoted the inflammatory cytokines secretion in macrophages.

CONCLUSIONS

This study demonstrated that NETs-induced macrophages inflammation to aggravate RA in Rab 5a dependent manner. Mechanically, Rab5a mediated internalisation of NETs by macrophages and NE contained in NETs promoted macrophages inflammatory cytokines secretion through NF-κB-light-chain-enhancer of activated B cells signal pathway. Therapeutic targeting Rab 5a or NE might extend novel strategies to minimise inflammation in RA.

Variations in Macrophage Activation Syndrome-associated Cardiac Diseases: A Report on Two Cases

Macrophage activation syndrome (MAS), a secondary hemophagocytic lymphohistiocytosis characterized by an excessive systemic inflammatory response, is a life-threatening and rare disease. Cardiovascular damage is a common and severe complication of the disease, however, it is easily ignored and not well studied. Herein, we report two cases of patients with MAS-associated heart damage and review the clinical characteristics, mechanism, and treatment. Case 1 along with systemic lupus erythematosus and Kikuchi necrotizing lymphadenitis occurred in fatal acute heart failure, and case 2 complicated adult-onset Still's Disease began with atrial fibrillation and had some improvement with the treatment of high dose corticosteroids. MAS-associated heart damage is a critical issue in clinical settings, and the etiology and mechanisms of MAS-associated cardiovascular diseases are likely multifactorial. The manifestations were various and high levels of the cytokines and cardiac damage may contribute to poor prognosis. Therefore, early intensive immunosuppressive therapy probably improves the treatment outcome.

Macrophage Activation Syndrome in Pediatric Systemic Lupus Erythematosus: A Systematic Review of the Diagnostic Aspects

Macrophage Activation Syndrome (MAS) is a very severe complication of different rheumatic diseases, including pediatric Systemic Lupus Erythematosus (pSLE). MAS is not considered as a frequent complication of pSLE; however, its occurrence could be under-estimated and the diagnosis can be challenging. In order to address this issue, we performed a systematic review of the available medical literature, aiming to retrieve all those papers providing diagnostic (clinical/laboratory) data on patients with pSLE-related MAS, in individual or aggregated form. The selected case reports and series provided a pool of 46 patients, accounting for 48 episodes of MAS in total. We re-analyzed these patients in light of the diagnostic criteria for MAS validated in systemic Juvenile Idiopathic Arthritis (sJIA) patients and the preliminary diagnostic criteria for MAS in pSLE, respectively. Five clinical studies were also selected and used to support this analysis. This systematic review confirms that MAS diagnosis in pSLE patients is characterized by several diagnostic challenges, which could lead to delayed diagnosis and/or under-estimation of this complication. Specific criteria should be considered to diagnose MAS in different rheumatic diseases; as regards pSLE, the aforementioned preliminary criteria for MAS in pSLE seem to perform better than the sJIA-related MAS criteria, because of a lower ferritin cut-off.

An autopsy series of an oft-missed ante-mortem diagnosis: hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a rare and potentially fatal syndrome resulting from a hyperactivated immune system. Diverse patient profiles and clinical presentations often result in misdiagnosis. This article describes the varied clinical presentations and autopsy findings in three patients with this entity. The etiopathogenesis of HLH, its disparate and confounding clinical features, the diagnostic criteria, and management principles are also briefly reviewed.

Intravenous immunoglobulin in macrophage activation syndrome associated with systemic lupus erythematosus

BACKGROUND

The hemophagocytic lymphohistiocytosis is a disease with a potential fatal evolution, caused by the activation of macrophages and histiocytes with hemophagocytosis in bone marrow and other reticuloendothelial systems, triggered by a defect in the T lymphocyte when stimulating the production of interleukin 1-beta, interleukin 6, interferon-gamma and tumor necrosis factor-alpha that promote macrophage activation. This condition presents with fever, cytopenias, splenomegaly, hemophagocytosis in bone marrow, hypertriglyceridemia and hypofibrinogenemia, in the context of an infectious, neoplastic or autoimmune disease. The objective of this article is to describe the utility of intravenous immunoglobulin (IVIg) in patients unable to receive immunosuppressive treatment.

CASE REPORTS

We present two case reports of systemic lupus erythematosus (SLE) with macrophage activation syndrome (MAS), one of them associated with central nervous system vasculitis and the other one with febrile neutropenia, both with bacterial infection added.

CONCLUSIONS

The diagnosis of MAS should be suspected in all patients with lupus activity, fever, cytopenias, visceromegalies, hypertriglyceridemia and hypofibrinogenemia. Diagnosis and treatment are important to significantly reduce mortality. It is proposed that the first line treatment in patients that present SLE associated with MAS and sepsis should be IgIV and as a second line immunosuppressants with intravenous steroids.

Visceral Leishmaniasis Associated with Macrophage Activation Syndrome and Diffuse Alveolar Hemorrhage in a Lupus Patient

Systemic lupus erythematosus is a heterogeneous and unpredictable autoimmune disease which can be complicated to approach and treat. Hemophagocytic lymphohistiocytosis and diffuse alveolar hemorrhage are rare disease complications. The authors describe a clinical case of a 32-year-old woman with lupus and fever of unknown origin. From the investigations performed, the myelogram revealed hemophagocytosis and Leishmania parasites, therefore liposomal amphotericin B was then started. In addition to directed therapy, she maintained fever that evolved with diffuse alveolar hemorrhage. The myelogram was repeated and showed that she still had hemophagocytosis but now without parasites. Corticotherapy was increased and intravenous Immunoglobulin was started, with improvement. Rituximab was started as a result of macrophage activation syndrome and diffuse alveolar hemorrhage. Months after discharge, she began once again to have sustained fever and Leishmania parasites were found again, therefore liposomal amphotericin B was started once more associated with miltefosine. She continues being followed-up as she is asymptomatic and using steroidsin weaning scheme.

Comparison of Different Diagnostic Guidelines for the Diagnosis of Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: Single Centre Experience

SUMMARY – Macrophage activation syndrome (MAS) is a potentially fatal complication of systemic juvenile idiopathic arthritis (sJIA), caused by exaggerated but ineffective immune response. The aim of the study was to compare the capacity of the HLH-2004 guidelines with the capacity of the MAS guidelines from 2005, and with the new set of classification criteria from 2016 in diagnosing MAS complicating sJIA. The study included 35 children aged 1-18 diagnosed with sJIA according to ILAR criteria and treated at the Department of Pediatrics, Division of Immunology and Rheumatology, Zagreb University Hospital Centre, in the period from 2009 to 2015. Out of 35 patients diagnosed with sJIA, there were 12 girls and 23 boys, with the mean age at disease onset (±SD) 5.51±3.65 years. Eight patients had flare of disease. With the guidelines from 2005, MAS was diagnosed in six (17.1%) patients with sJIA. With the new set of classification criteria from 2016, MAS was diagnosed in four (11.4%) patients with sJIA. MAS was not diagnosed with the HLH-2004 guidelines. In our study, four out of six patients had MAS at the onset of sJIA, and in the rest two it occurred during relapse. Two patients with MAS developed full-blown clinical picture while another four had incomplete clinical features with minor laboratory alteration. Due to the use of different diagnostic guidelines, we found difference in the prevalence of MAS. It was slightly higher in comparison to available studies, while other researched features, such as clinical characteristics, were similar.

Macrophage Activation Syndrome Associated With Adult Onset Still's Disease

Macrophage activation syndrome (MAS) is a potentially lethal complication of chronic rheumatological conditions like ankylosing spondylitis, rheumatoid arthritis, and adult-onset Still's disease (AOSD). It is a multisystem inflammatory syndrome caused by immense cytokine release from activated lymphocytes and macrophages. We give an account of the incidence of a twenty years old Asian girl suffering from non-remitting fever and an evanescent rash for last ten weeks. Physical examination and laboratory work-up suggested high grade fever, pancytopenia, hyperferritinemia, hypertriglyceridemia, hypofibrinogenemia and impaired liver function. Bone marrow biopsy was also done. It showed active hemophagocytosis. She was diagnosed as a case of Macrophage Activation Syndrome associated with Adult Onset Still's disease. She was treated with high dose steroids and cyclosporine and recovered completely.