Cytokine profiles of macrophage activation syndrome associated with rheumatic diseases

How underappreciated autoinflammatory (innate immunity) mechanisms dominate disparate autoimmune disorders

Historically inflammation against self was considered autoimmune which stems back to the seminal observations by Ehrlich who described serum factors, now known to be autoantibodies produced by B lineage cells that mediate "horror autotoxicus". The 20th century elucidation of B- and T-cell adaptive immune responses cemented the understanding of the key role of adaptive immune responses in mediating pathology against self. However, Mechnikov shared the Nobel Prize for the discovery of phagocytosis, the most rudimentary aspect of innate immunity. Fast forward some 100 years and an immunogenetic understanding of innate immunity led to the categorising of innate immunopathology under the umbrella term 'auto inflammation' and terminology such as "horror autoinflammaticus" to highlight the schism from the classical adaptive immune understanding of autoimmunity. These concepts lead to calls for a two-tiered classification of inflammation against self, but just as innate and adaptive immunity are functionally integrated, so is immunopathology in many settings and the concept of an autoimmune to autoinflammation continuum emerged with overlaps between both. Herein we describe several historically designated disorders of adaptive immunity where innate immunity is key, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD) where the immunopathology phenotype is strongly linked to major histocompatibility complex (MHC) class II associations and responds to drugs that target T-cells. We also consider MHC-I-opathies including psoriasis and Behcet's disease(BD) that are increasingly viewed as archetype CD8 T-cell related disorders. We also briefly review the key role of barrier dysfunction in eczema and ulcerative colitis (UC) where innate tissue permeability barrier dysfunction and microbial dysbiosis contributes to prominent adaptive immune pathological mechanisms. We also highlight the emerging roles of intermediate populations of lymphocytes including gamma delta (γδ) and mucosal-associated invariant T (MAIT) cells that represent a blend of adaptive immune plasticity and innate immune rapid responders that may also determine site specific patterns of inflammation.

Serum cytokine panels in pediatric clinical practice

BACKGROUND

Cytokines are soluble signaling proteins that regulate inflammation and coordinate immune responses. Serum cytokine panels are increasingly used in medical practice, yet our understanding of cytokines as biomarkers for disease remains limited.

OBJECTIVE

We sought to analyze real-world single-center use of a multiplexed cytokine panel, correlate its results with diagnosis and severity, and explore its use in pediatric practice.

METHODS

A multiplexed cytokine panel, able to return same-day results, was implemented in April 2020 at the Children's Hospital of Philadelphia (Philadelphia, Pa) and its performance was validated for clinical use. Coded patient data were collected using the REDCap database, and correlations between cytokine levels and outcomes of interest were analyzed retrospectively.

RESULTS

Cytokine levels correlate with acuity of care, with patients admitted to the pediatric intensive care unit having the highest cytokine values. Patients with familial hemophagocytic lymphohistiocytosis (fHLH) showed prominent peaks in IFN-γ, IL-10, and TNF, whereas patients with sepsis exhibited high IL-6 and IL-8 with relatively modest IFN-γ. Cytokine release syndrome (CRS) after chimeric antigen receptor T-cell therapy often demonstrated pan-panel positivity at peak levels, with a similar pattern as that of fHLH. A ratio of [IFN-γ] + [IL-10]/[IL-6] + [IL-8] levels was able to distinguish fHLH and CRS from severe sepsis.

CONCLUSIONS

Cytokine levels correlate with severity of illness and can help differentiate between syndromes that present similarly, including fHLH and CRS compared with sepsis. Cytokine panels can be used as biomarkers to inform diagnosis and management decisions, but significant work remains to dissect complex clinical patterns of disease.

An antibody to IL-1 receptor 7 protects mice from LPS-induced tissue and systemic inflammation

Introduction

Interleukin-18 (IL-18), a pro-inflammatory cytokine belonging to the IL-1 Family, is a key mediator ofautoinflammatory diseases associated with the development of macrophage activation syndrome (MAS).High levels of IL-18 correlate with MAS and COVID-19 severity and mortality, particularly in COVID-19patients with MAS. As an inflammation inducer, IL-18 binds its receptor IL-1 Receptor 5 (IL-1R5), leadingto the recruitment of the co-receptor, IL-1 Receptor 7 (IL-1R7). This heterotrimeric complex subsequentlyinitiates downstream signaling, resulting in local and systemic inflammation.

Methods

We reported earlier the development of a novel humanized monoclonal anti-human IL-1R7 antibody whichspecifically blocks the activity of human IL-18 and its inflammatory signaling in human cell and wholeblood cultures. In the current study, we further explored the strategy of blocking IL-1R7 inhyperinflammation in vivo using animal models.

Results

We first identified an anti-mouse IL-1R7 antibody that significantly suppressed mouse IL-18 andlipopolysaccharide (LPS)-induced IFNg production in mouse splenocyte and peritoneal cell cultures. Whenapplied in vivo, the antibody reduced Propionibacterium acnes and LPS-induced liver injury and protectedmice from tissue and systemic hyperinflammation. Importantly, anti-IL-1R7 significantly inhibited plasma,liver cell and spleen cell IFNg production. Also, anti-IL-1R7 downregulated plasma TNFa, IL-6, IL-1b,MIP-2 production and the production of the liver enzyme ALT. In parallel, anti-IL-1R7 suppressed LPSinducedinflammatory cell infiltration in lungs and inhibited the subsequent IFNg production andinflammation in mice when assessed using an acute lung injury model.

Discussion

Altogether, our data suggest that blocking IL-1R7 represents a potential therapeutic strategy to specificallymodulate IL-18-mediated hyperinflammation, warranting further investigation of its clinical application intreating IL-18-mediated diseases, including MAS and COVID-19.

Heterogeneity of macrophage activation syndrome and treatment progression

Macrophage activation syndrome (MAS) is a rare complication of autoimmune inflammatory rheumatic diseases (AIIRD) characterized by a progressive and life-threatening condition with features including cytokine storm and hemophagocytosis. Predisposing factors are typically associated with microbial infections, genetic factors (distinct from typical genetically related hemophagocytic lymphohistiocytosis (HLH)), and inappropriate immune system overactivation. Clinical features include unremitting fever, generalized rash, hepatosplenomegaly, lymphadenopathy, anemia, worsening liver function, and neurological involvement. MAS can occur in various AIIRDs, including but not limited to systemic juvenile idiopathic arthritis (sJIA), adult-onset Still's disease (AOSD), systemic lupus erythematosus (SLE), Kawasaki disease (KD), juvenile dermatomyositis (JDM), rheumatoid arthritis (RA), and Sjögren's syndrome (SS), etc. Although progress has been made in understanding the pathogenesis and treatment of MAS, it is important to recognize the differences between different diseases and the various treatment options available. This article summarizes the cell types and cytokines involved in MAS-related diseases, the heterogeneity, and treatment options, while also comparing it to genetically related HLH.

Differences and similarities in cytokine profiles of macrophage activation syndrome in systemic lupus erythematosus and adult-onset Still's disease

To clarify the differences and similarities in the cytokine profiles of macrophage activating syndrome (MAS) between systemic lupus erythematosus (SLE) and adult-onset Still's disease (AOSD). The study participants included 9 patients with MAS-SLE, 22 with non-MAS-SLE, 9 with MAS-AOSD, and 13 with non-MAS-AOSD. Serum cytokine levels were measured using a multiplex bead assay. Cytokine levels were compared between patients with SLE and AOSD with/without MAS. Moreover, cytokine patterns were examined using principal component analysis (PCA) and cluster analysis. IL-6, IL-8, IL-18, and TNF-α levels were elevated in patients with SLE and AOSD. IFN-α levels were elevated in SLE, whereas IL-1β and IL-18 levels were elevated in AOSD. In SLE, IFN-α and IL-10 levels were higher in MAS than in non-MAS and controls. PCA revealed distinctive cytokine patterns in SLE and AOSD, SLE with IFN-α and IP-10, AOSD with IL-1β, IL-6, and IL-18, and enhanced cytokine production in MAS. PCA and cluster analysis showed no differences in cytokine patterns between the MAS and non-MAS groups. However, serum ferritin levels were correlated with IFN-α levels in SLE. Cytokine profiles differed between SLE and AOSD but not between MAS and non-MAS. MAS is induced by the enhancement of underlying cytokine abnormalities rather than by MAS-specific cytokine profiles. Type I IFN may be involved in MAS development in patients with SLE.

Adult-onset Still's disease complicated by macrophage activation syndrome

Key Clinical Message

Young patients with persistent rash and fevers despite antibiotic treatment should be evaluated for non-infectious etiologies. In our patient's case, these findings led to a diagnosis of MAS, which ultimately affected how she was managed.

Abstract

Adult-onset Still's disease (AOSD) is a rare, often difficult to diagnose autoimmune disease that typically presents as a rash, unresolving fevers and joint pains capable of mimicking a number of autoimmune diseases. Here, we present the case of a young postpartum woman whose clinical presentation, which included a pruritic maculopapular rash that evolved to include a flagellate component, and serological studies, chief among them cytopenias and a Ferritin >15,000 nm/mL) allowed us to make an early diagnosis of AOSD complicated by macrophage activation syndrome. We discuss the treatment for AOSD complicated by MAS with Hydrocortisone and Anakinra, the final discharge regimen prescribed for our patient, and report on her state 3 months post-hospitalization, which was favorable. Our case is unique because we ultimately believe that pregnancy itself triggered her ASOD, because of how the quality of the flagellate component of her rash allowed us to narrow the differential diagnosis, and because of how the significant cytopenias and significant liver dysfunction alerted us to the possibility of MAS.

Adult-Onset Still's Disease-A Complex Disease, a Challenging Treatment

Adult-onset Still's disease (AOSD) is a systemic inflammatory disorder with an unknown cause characterized by high-spiking fever, lymphadenopathy, hepatosplenomegaly, hyperferritinemia, and leukocytosis. The clinical course can be divided into three significant patterns, each with a different prognosis: Self-limited or monophasic, intermittent or polycyclic systemic, and chronic articular. Two criteria sets have been validated. The Yamaguchi criteria are the most generally used, although the Fautrel criteria offer the benefit of adding ferritin and glycosylated ferritin values. AOSD's pathogenesis is not yet completely understood. Chemokines and pro-inflammatory cytokines, including interferon (IFN)-γ, tumor necrosis factor α (TNFα), interleukin (IL)-1, IL-6, IL-8, and IL-18, play a crucial role in the progression of illness, resulting in the development of innovative targeted therapeutics. There are no treatment guidelines for AOSD due to its rarity, absence of controlled research, and lack of a standard definition for remission and therapy objectives. Non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids (CS), and conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) are used in AOSD treatment. Biological therapy, including IL-1, IL-6, IL-18, and IL-17 inhibitors, as well as TNFα or Janus-kinases (JAKs) inhibitors, is administered to patients who do not react to CS and csDMARDs or achieve an inadequate response.

Interleukin-18: a biomarker with therapeutic potential in adult-onset Still's disease

INTRODUCTION

Adult-onset Still's disease (AOSD) is an autoinflammatory disease driven by the innate immune response. Given the ambiguity in clinical presentation and lack of specific diagnostic biomarkers, AOSD diagnosis is usually delayed in the early stage. Because AOSD is a rare disease with clinical heterogeneity, there is no consensus on its treatment currently. This review summarizes the current research evidence regarding the pathogenic role and the diagnostic or therapeutic potential of interleukin (IL)-18 in AOSD.

AREAS COVERED

We searched the MEDLINE database using the PubMed interface and reviewed English-language literature from 1971 to 2022. This review focusing on IL-18 discusses its pathogenic role and clinical implications in AOSD.

EXPERT OPINION

NLRP3-inflammasome activation with IL-18 overproduction plays a pathogenic role in AOSD. IL-18 is closely linked to the clinical manifestations and disease activity of AOSD and may be a diagnostic biomarker. Given its pathogenic role in AOSD, IL-18 could become a potential therapeutic target. IL-18 binding protein (IL-18BP) negatively regulates the biological activity of IL-18 by inhibiting IL-18 signaling, and a clinical trial revealed that IL-18BP (Tadekinig alfa) treatment was well-tolerated and effective for AOSD. Recently, monoclonal antibodies against IL-18 have been under evaluation in a phase 1b trial.

Macrophage activation syndrome in patients with adult-onset Still's disease under tocilizumab treatment: A single-center observational study

OBJECTIVES

Macrophage activation syndrome (MAS) developed under tocilizumab treatment poses a diagnostic challenge. This study aims to demonstrate the frequency and the clinical features of MAS developed in patients with adult-onset Still's disease (AOSD) receiving tocilizumab.

METHODS

The consecutive AOSD patients treated with tocilizumab in our institution from April 2008 to March 2020 were studied. The frequency of clinically diagnosed MAS during tocilizumab treatment, their conformity to the several criteria relevant for MAS, and laboratory characteristics compared to AOSD flare were investigated.

RESULTS

Of the 20 AOSD patients treated with tocilizumab, six developed clinically diagnosed MAS, four immediately after starting tocilizumab and two after long-term treatment. Some of them had already met the MAS criteria before starting tocilizumab. At MAS diagnosis, although some did not meet the MAS criteria due to lack of fever and/or the lower ferritin levels, all consistently showed sharp increases in ferritin along with marked abnormal changes in two or more different markers of organ damage, unlike the AOSD flares.

CONCLUSION

MAS is not a rare complication in AOSD patients receiving tocilizumab. The clinical similarities between systemic AOSD and MAS, and substantial alterations in MAS features by inhibition of interleukin-6 signaling may limit the utility of the existing diagnostic/classification criteria in diagnosing MAS under tocilizumab treatment. The emergence of abnormalities in MAS-related organ damage markers with a rapid elevation of ferritin should be considered as MAS development in AOSD patients receiving tocilizumab even if the patients are afebrile or have relatively low ferritin levels.

Usefulness of Interleukin-18 as a Diagnostic Biomarker to Differentiate Adult-Onset Still's Disease With/Without Macrophage Activation Syndrome From Other Secondary Hemophagocytic Lymphohistiocytosis in Adults

Background

Interleukin (IL)-18 is markedly elevated in systemic inflammatory diseases that cause the ‘cytokine storm’ such as adult-onset Still’s disease (AOSD) and hemophagocytic lymphohistiocytosis (HLH). The differences in IL-18 between AOSD and HLH, especially in adults, is uncertain. Macrophage activation syndrome (MAS), a form of secondary HLH, is often difficult to differentiate cases of AOSD that include MAS from other secondary HLH. In this case-control study, we investigated whether serum IL-18 levels could be a useful biomarker for the differential diagnosis of AOSD with or without MAS (AOSD group) and other secondary HLH in adults (adult HLH group).

Patients and Methods

We enrolled 46 patients diagnosed with AOSD including 9 patients with MAS and 31 patients in the adult HLH group, which excluded AOSD-associated MAS. The clinical features and laboratory data were compared between the AOSD and adult HLH groups. In addition, we subdivided the AOSD group (with or without MAS) and the adult HLH group (whether lymphoma-associated or not) and compared the four groups. A logistic regression analysis was used to identify factors with high efficacy in differentiating the two groups, followed by a receiver operating characteristic (ROC) curve analysis to evaluate the differential diagnostic ability of IL-18. We analyzed the correlation between IL-18 and various laboratory parameters in the AOSD group.

Results

Serum IL-18 levels of patients in the AOSD groups were significantly higher than those of the adult HLH groups, and were closely correlated with ferritin, soluble interleukin-2 receptor (sIL-2R), and other laboratory data. Univariate and multivariate logistic regression analyses revealed that IL-18, sIL-2R, and ‘arthralgia or arthritis’ are independent factors useful in the differential diagnosis of AOSD from adult HLH. In the differential diagnosis of both groups, the area under the curve obtained from the ROC curve of IL-18 with a cutoff value of 18,550 pg/mL was 0.91 (95% confidence interval 0.83–1.00; sensitivity 90.3%, specificity 93.5%), and the differential diagnosis ability of IL-18 was superior to that of other laboratory data.

Conclusions

IL-18 could be a useful biomarker for the differential diagnosis of AOSD and adult HLH.

Current and emerging biological therapy in adult-onset Still's disease

Adult-onset Still's disease (AOSD) is a rare, but characteristic non-familial, multi-genic systemic auto-inflammatory disorder, characterized by high spiking fever, salmon-like evanescent skin rash, polyarthritis, sore throat, hyperferritinemia and leucocytosis. The hallmark of AOSD is a cytokine storm triggered by dysregulation of inflammation. Nowadays, with advances in anti-cytokine biologic agents, the treatment of AOSD is no longer limited to NSAIDs, glucocorticoids or conventional synthetic DMARDs. In this review, we focussed on the roles of these cytokines in the pathogenesis of AOSD and summarized the current and emerging biological therapy.

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.

Hide and seek in a pandemic: review of SARS-CoV-2 infection and sequelae in children

New Findings

What is the topic of this review?

A description of the current literature relating to COVID‐19 infection in children and the associated inflammatory condition, paediatric multi‐inflammatory syndrome temporally associated with SARS‐CoV‐2 (PIMS‐TS).

What advances does it highlight?

Children with SARS‐CoV‐2 infection have a distinct clinical phenotype when compared to adults. This may relate to relative differences in their adaptive immunity and in the degree and distribution of expression of the SARS‐CoV‐2 receptor (angiotensin‐converting enzyme 2). There are several similarities between PIMS‐TS, Kawasaki disease shock syndrome and other known inflammatory disorders such as macrophage activation syndrome. Few data are available to date regarding vaccination responses of children against COVID‐19.

Abstract

Children infected with SARS‐CoV‐2 have a clinical phenotype that is distinct from that observed in adult cases. They can present with a range of respiratory, gastrointestinal and neurological symptoms, or with a delayed hyperinflammatory syndrome (paediatric multisystem inflammatory system temporally associated with SARS‐CoV‐2; PIMS‐TS) that frequently requires treatment in an intensive care unit. These manifestations may be related to unique expression of transmembrane receptors and immune physiology in children. The clinical features and inflammatory profile of PIMS‐TS are similar to other inflammatory disorders that occur in children such as Kawasaki disease, macrophage activation syndrome and sepsis. Given children are infected less frequently and have less severe disease due to COVID‐19 compared to adults, their physiological profile is of great interest. An understanding of the unique mechanisms of infection and disease in children could aid the identification of potential therapeutic targets. Like adults, children can have long‐term complications of SARS‐CoV‐2 infection, including neurological and cardiac morbidity. Vaccination against SARS‐CoV‐2 is not yet authorised in children aged <12 years, and hence we anticipate ongoing paediatric presentations of COVID‐19 in the coming months.

An Update on the Pathogenic Role of Macrophages in Adult-Onset Still's Disease and Its Implication in Clinical Manifestations and Novel Therapeutics

Increasing evidence indicates a pivotal role of macrophages in innate immunity, which contributes to the pathogenesis of adult-onset Still's disease (AOSD). Despite the available reviews that summarized the pathogenic role of proinflammatory cytokines in AOSD, a systematic approach focusing on the crucial role of macrophages in this disease is still lacking. This review summarizes the updated functions of macrophages in AOSD and their implication in clinical manifestations and therapeutics. We searched the MEDLINE database using the PubMed interface and reviewed the English-language literature as of 31 March 2021, from 1971 to 2021. We focus on the existing evidence on the pathogenic role of macrophages in AOSD and its implication in clinical characteristics and novel therapeutics. AOSD is an autoinflammatory disease mainly driven by the innate immune response. Among the innate immune responses, macrophage activation is a hallmark of AOSD pathogenesis. The pattern recognition receptors (PRRs) on macrophages recognize pathogen-associated molecular patterns and damage-associated molecular patterns and subsequently cause overproduction of proinflammatory cytokines and recruit adaptive immunity. Some biomarkers, such as ferritin and gasdermin D, reflecting macrophage activation were elevated and correlated with AOSD activity. Given that macrophage activation with the overproduction of proinflammatory cytokines plays a pathogenic role in AOSD, these inflammatory mediators would be the therapeutic targets. Accordingly, the inhibitors to interleukin- (IL-) 1, IL-6, and IL-18 have been shown to be effective in AOSD treatment. Gaining insights into the pathogenic role of macrophages in AOSD can aid in identifying disease biomarkers and therapeutic agents for this disease.

A novel anti-human IL-1R7 antibody reduces IL-18-mediated inflammatory signaling

Unchecked inflammation can result in severe diseases with high mortality, such as macrophage activation syndrome (MAS). MAS and associated cytokine storms have been observed in COVID-19 patients exhibiting systemic hyperinflammation. Interleukin-18 (IL-18), a proinflammatory cytokine belonging to the IL-1 family, is elevated in both MAS and COVID-19 patients, and its level is known to correlate with the severity of COVID-19 symptoms. IL-18 binds its specific receptor IL-1 receptor 5 (IL-1R5, also known as IL-18 receptor alpha chain), leading to the recruitment of the coreceptor, IL-1 receptor 7 (IL-1R7, also known as IL-18 receptor beta chain). This heterotrimeric complex then initiates downstream signaling, resulting in systemic and local inflammation. Here, we developed a novel humanized monoclonal anti-IL-1R7 antibody to specifically block the activity of IL-18 and its inflammatory signaling. We characterized the function of this antibody in human cell lines, in freshly obtained peripheral blood mononuclear cells (PBMCs) and in human whole blood cultures. We found that the anti-IL-1R7 antibody significantly suppressed IL-18-mediated NFκB activation, reduced IL-18-stimulated IFNγ and IL-6 production in human cell lines, and reduced IL-18-induced IFNγ, IL-6, and TNFα production in PBMCs. Moreover, the anti-IL-1R7 antibody significantly inhibited LPS- and Candida albicans–induced IFNγ production in PBMCs, as well as LPS-induced IFNγ production in whole blood cultures. Our data suggest that blocking IL-1R7 could represent a potential therapeutic strategy to specifically modulate IL-18 signaling and may warrant further investigation into its clinical potential for treating IL-18-mediated diseases, including MAS and COVID-19.

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.

Macrophage activation syndrome in systemic lupus erythematosus and systemic-onset juvenile idiopathic arthritis: a retrospective study of similarities and dissimilarities

Macrophage activation syndrome (MAS) is a serious complication of rheumatic diseases. Fever and hyperferritinemia are common in active systemic-onset juvenile idiopathic arthritis (sJIA) and cytopenia in active systemic lupus erythematosus (SLE), thus recognizing MAS in them is a challenge. We compared clinical and laboratory parameters, various classification criteria, and outcomes of MAS in SLE and sJIA. Clinical and laboratory data were extracted from case records of patients with clinician diagnosed cases of SLE-MAS (adult and pediatric) and sJIA-MAS, admitted (2004-2018) at a tertiary care hospital. Ravelli, International consensus, HLH-2004, and criteria proposed by Parodi et al. were applied and compared. Among 33 patients (18 females) with MAS, 19 had SLE (7, childhood-onset SLE) and 14 had sJIA. MAS was more likely to be the presenting manifestation of disease in SLE (p < 0.05). There were no differences in the clinical features among them. Patients with SLE-MAS had lower baseline total leucocyte and platelet counts (p < 0.01), whereas patients with sJIA-MAS had significantly higher median CRP (p = 0.002), fall in TLC (p = 0.012), delta ESR/CRP ratio (p = 0.02), and lower fibrinogen level (p = 0.006). Neutrophil-to-lymphocyte ratio, ferritin/CRP ratio, and the number of patients with ferritin/ESR > 80 were similar. Only 6/33(18%) fulfilled the HLH criteria. Criteria meant for sJIA-MAS or SLE-MAS performed well for both diseases and the majority of patients could be diagnosed using them. Two patients died in each group. MAS in SLE and sJIA is more similar than dissimilar in clinical features and outcome. Criteria meant for MAS in sJIA or SLE-MAS performed equally well in both diseases.

miR-1207-5p Can Contribute to Dysregulation of Inflammatory Response in COVID-19 via Targeting SARS-CoV-2 RNA

The present study focuses on the role of human miRNAs in SARS-CoV-2 infection. An extensive analysis of human miRNA binding sites on the viral genome led to the identification of miR-1207-5p as potential regulator of the viral Spike protein. It is known that exogenous RNA can compete for miRNA targets of endogenous mRNAs leading to their overexpression. Our results suggest that SARS-CoV-2 virus can act as an exogenous competing RNA, facilitating the over-expression of its endogenous targets. Transcriptomic analysis of human alveolar and bronchial epithelial cells confirmed that the CSF1 gene, a known target of miR-1207-5p, is over-expressed following SARS-CoV-2 infection. CSF1 enhances macrophage recruitment and activation and its overexpression may contribute to the acute inflammatory response observed in severe COVID-19. In summary, our results indicate that dysregulation of miR-1207-5p-target genes during SARS-CoV-2 infection may contribute to uncontrolled inflammation in most severe COVID-19 cases.

Current treatment options and safety considerations when treating adult-onset Still's disease

INTRODUCTION

Adult onset Still disease (AOSD) is a rare systemic inflammatory condition. The clinical spectrum of this disease ranges from self-limiting forms with mild symptoms to life-threatening cases. Glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs) represent the first line of therapy for AOSD, with add-on therapy with second-line drug reserved to steroid-dependent patients and in life-threatening cases. Currently, early treatment with conventional disease modifying anti-rheumatic drugs (DMARDs) and biologic agents blocking causal cytokines is advocated in patients with severe and recalcitrant clinical manifestations.

AREAS COVERED

This review analyzes the available controlled evidence and observational data regarding the efficacy and safety of conventional and biological pharmacological agents in the treatment of AOSD.

EXPERT OPINION

Non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids are effective in controlling clinical manifestations in the majority of AOSD patients. Conventional DMARDs can be 20 effective in some severe and steroid-dependent cases of AOSD; however, anti-cytokine agents represent an effective and overall more suitable alternative in this specific subset of patients. IL-1 and IL-6 blockade are effective in treating systemic and articular inflammation of AOSD patients. IL-1 blockade also has an excellent safety profile and therefore represent the first choice of biologic treatment in this clinical scenario.

Autoinflammatory Pathogenesis and Targeted Therapy for Adult-Onset Still's Disease

Adult-onset Still's disease (AOSD) is a rare multisystem autoinflammatory disorder of unknown etiology. AOSD is generally characterized by high spiking fever, arthralgia or arthritis, skin rash, leukocytosis, and hyperferritinemia. Traditionally, AOSD has been treated with non-steroidal anti-inflammatory drugs, corticosteroids, and immunosuppressants. An increasing number of studies have shown that proinflammatory cytokines, such as interleukin-1β, -18, -6, and tumor necrosis factor-α, play key roles in AOSD and may serve as therapeutic targets. In the current review, we provided insights into the roles of these cytokines in the pathogenesis of AOSD and also provided a commentary on the clinical studies of biologic therapy against AOSD.

Pro-inflammatory properties of H-ferritin on human macrophages, ex vivo and in vitro observations

Ferritin is an iron-binding molecule, which comprises 24 subunits, heavy (FeH) and light (FeL) subunits, suggested to have a pathogenic role by the 'hyperferritinemic syndrome'. In this work, we tested (1) FeH and FeL in bone marrow (BM) and sera in patients with macrophage activation syndrome (MAS); (2) pro-inflammatory effects of ferritin, FeL, and FeH on macrophages; (3) ability of FeH-stimulated macrophages to stimulate the proliferation of peripheral blood mononuclear cells (PBMCs); (4) production of mature IL-1β and IL-12p70 in extracellular compartments of FeH-stimulated macrophages. Immunofluorescence analysis and liquid chromatography mass spectrometry (LC-MS/MS) based proteomics were performed to identify FeL and FeH in BM and sera, respectively, in the same patients. Macrophages were stimulated with ferritin, FeH, and FeL to assess pro-inflammatory effects by RT-PCR and western blot. The proliferation of co-cultured PBMCs with FeH-stimulated macrophages was tested. Immunofluorescence showed an increased FeH expression in BMs, whereas LC-MS/MS identified that FeL was mainly represented in sera. FeH induced a significant increase of gene expressions of IL-1β, IL-6, IL-12, and TNF-α, more marked with FeH, which also stimulated NLRP3. FeH-stimulated macrophages enhanced the proliferation of PBMCs. The ELISA assays showed that mature form of IL-1β and IL-12p70 were increased, in extracellular compartments of FeH-stimulated macrophages. Our results showed FeH in BM biopsies of MAS patients, whereas, LC-MS/MS identified FeL in the sera. FeH showed pro-inflammatory effects on macrophages, stimulated NLRP3, and increased PBMCs proliferation.

Genetic Association and Expression Correlation between Colony-Stimulating Factor 1 Gene Encoding M-CSF and Adult-Onset Still's Disease

Adult-onset Still's disease (AOSD) is a rare and inflammatory disorder characterized by spiking fever, rash, arthritis, and multisystemic involvement. HLA has been shown to be associated with AOSD; however, it could not explain the innate immunity and autoinflammatory characteristics of AOSD. To assess the genetic susceptibility of AOSD, we conducted a genome-wide association study (GWAS) on a cohort of 70 AOSD cases and 688 controls following a replication study of 36 cases and 200 controls and meta-analysis. The plasma concentrations of associated gene product were determined. The GWAS, replication, and combined sample analysis confirmed that SNP rs11102024 on 5'-upstream of CSF1 encoding macrophage colony-stimulating factor (M-CSF) was associated with AOSD (P = 1.20 × 10^-8, OR (95% CI): 3.28 (2.25~4.79)). Plasma levels of M-CSF increased in AOSD patients (n = 82, median: 9.31 pg/mL), particularly in the cases with activity score ≥ 6 (n = 42, 10.94 pg/mL), compared to the healthy donors (n = 68, 5.31 pg/mL) (P < 0.0001). Patients carrying rs11102024TT genotype had higher M-CSF levels (median: 20.28 pg/mL) than those with AA genotype (6.82 pg/mL) (P < 0.0001) or AT genotype (11.61 pg/mL) (P = 0.027). Patients with systemic pattern outcome were associated with elevated M-CSF and frequently observed in TT carriers. Our data suggest that genetic variants near CSF1 are associated with AOSD and the rs11102024 T allele links to higher M-CSF levels and systemic outcome. These results provide a promising initiative for the early intervention and therapeutic target of AOSD. Further investigation is needed to have better understandings and the clinical implementation of genetic variants nearby CSF1 in AOSD.

Usefulness of soluble CD163 as a biomarker for macrophage activation syndrome associated with systemic lupus erythematosus

OBJECTIVE

We aimed to study the usefulness of serum soluble CD163 (sCD163) as a biomarker for macrophage activation syndrome (MAS) associated with systemic lupus erythematosus (SLE).

METHODS

Serum sCD163 levels were retrospectively measured by enzyme-linked immunosorbent assay for SLE patients associated with MAS (SLE-MAS), lupus nephritis (LN), or autoimmune hemolytic anemia (AIHA) and/or immune thrombocytopenia (ITP) and healthy controls (HCs). Posttreatment samples were also evaluated in the available SLE-MAS patients. The associations between serum sCD163 levels and clinical information were statistically analyzed.

RESULTS

The serum sCD163 levels in SLE-MAS, LN and SLE-AIHA/ITP groups were significantly higher than those in HCs (n = 17, 29, 13, and 68, respectively; p < 0.01 for all comparisons). In addition, the serum sCD163 levels in the SLE-MAS group were even higher than those in the LN and SLE-AIHA/ITP groups (p < 0.01 for both comparisons). Serum sCD163 levels were correlated with the SLE Disease Activity Index 2000 scores (r = 0.53), whereas they were not correlated with the serum ferritin levels. With the determined cut-off value, the sensitivity and specificity of serum sCD163 for the diagnosis of SLE-MAS were 59% and 86%, respectively. Retesting showed that the serum sCD163 levels decreased significantly following treatment in parallel with disease amelioration in the SLE-MAS group (p < 0.01).

CONCLUSIONS

The present study suggests the usefulness of serum sCD163 as a diagnostic and disease-activity biomarker for SLE-associated MAS. Serum sCD163 might also have a different role as a biomarker for SLE-associated MAS than serum ferritin does.

Adult-Onset Still’s Disease

Adult-onset Still’s disease (AoSD) is a rare but clinically well-known, polygenic, systemic autoinflammatory disease. It is typically characterized by four main (cardinal) symptoms: spiking fever ≥39 °C, arthralgia or arthritis, skin rash, and hyperleukocytosis (≥10,000 cells/mm³). However, many other clinical features are possible, and it can appear in all age groups with potentially severe inflammatory onset accompanied by a broad spectrum of disease manifestation and complications. Hence, it remains a diagnostic challenge, and the clinician should first rule out infectious, tumoral, or inflammatory differential diagnoses. Determination of the total and glycosylated ferritin levels, although not pathognomonic, can help in diagnosis. New biomarkers have recently been described, but they need to be validated. The disease evolution of AoSD can be monocyclic, polycyclic, or chronic. In chronic disease, a joint involvement is often predominant, and erosions are noted in one-third of patients. Many progresses have been made in the understanding of the pathogenesis over the last decades. This chapter provides a comprehensive insight into the complex and heterogeneous nature of AoSD describing the identified cytokine signaling pathways and biomarkers. It also discusses the current evidence for the usage of biologics in AoSD to provide guidance for treatment decisions, taking into account both the efficacy and the safety of the different therapeutic options.

Mechanisms, biomarkers and targets for adult-onset Still's disease

Adult-onset Still’s disease (AoSD) is a rare but clinically well-known, polygenic, systemic autoinflammatory disease. Owing to its sporadic appearance in all adult age groups with potentially severe inflammatory onset accompanied by a broad spectrum of disease manifestation and complications, AoSD is an unsolved challenge for clinicians with limited therapeutic options. This Review provides a comprehensive insight into the complex and heterogeneous nature of AoSD, describing biomarkers of the disease and its progression and the cytokine signalling pathways that contribute to disease. The efficacy and safety of biologic therapeutic options are also discussed, and guidance for treatment decisions is provided. Improving the approach to AoSD in the future will require much closer cooperation between paediatric and adult rheumatologists to establish common diagnostic strategies, treatment targets and goals.

Adult-onset Still’s disease (AoSD) is not easily diagnosed, and treatment options are limited. This Review provides an overview of the disease and its pathogenesis, clinical trial results, therapeutic options and a plan to diagnose and clinically manage these patients.

Similar to systemic-onset juvenile idiopathic arthritis, adult-onset Still’s disease (AoSD) is a rare systemic autoinflammatory disease with potentially severe inflammatory onset accompanied by a broad spectrum of disease manifestation and complications.

AoSD should be considered in patients with persistent fever, and the diagnosis is based on the combination of clinical and laboratory findings as well as the exclusion of other inflammatory conditions.

Central to the pathogenesis of AoSD is the intense activation of innate immune cells and overproduction of several pro-inflammatory cytokines including IL-1, IL-6 and IL-18.

Two IL-1 antagonists have been approved for treatment of AoSD, and growing evidence suggests that other biologic agents are therapeutic options, such as anti-IL-6 and anti-IL-18 therapeutics.

As a reliable prediction of response and outcome is not possible, therapeutic decisions have to be made on the basis of clinical, biological or imaging characteristics of disease.

A close cooperation between paediatric and adult rheumatologists is required to establish common diagnostic strategies, treatment targets and goals.

Generation and characterization of antagonistic anti-human interleukin (IL)-18 monoclonal antibodies with high affinity: Two types of monoclonal antibodies against full-length IL-18 and the neoepitope of inflammatory caspase-cleaved active IL-18

Interleukin-18 (IL-18) is a pro-inflammatory cytokine that evokes both innate and acquired immune responses. IL-18 is initially synthesized as an inactive precursor and the cleavage for processing into a mature, active molecule is mediated by pro-inflammatory caspases following the activation of inflammasomes. Two types of monoclonal antibodies were raised: anti-IL-18^63-68 antibodies which recognize full-length^1-193 and cleaved IL-18; and anti-IL-18 neoepitope antibodies which specifically recognize the new N-terminal ³⁷YFGKLESK⁴⁴ of IL-18 cleaved by pro-inflammatory caspase-1/4. These mAbs were suitable for Western blotting, capillary Western immunoassay (WES), immunofluorescence, immunoprecipitation, and function-blocking assays. WES analysis of these mAbs allowed visualization of the IL-18 bands and provided a molecular weight corresponding to the pro-inflammatory caspase-1/4 cleaved, active form IL-18^37-193, and not to the inactive precursor IL-18, in the serum of patients with adult-onset Still's disease (6/14, 42%) and hemophagocytic activation syndrome (2/6, 33%). These monoclonal antibodies will be very useful in IL-18 and inflammasome biology and for diagnostic and therapeutic strategies for inflammatory diseases.

Macrophage activation syndrome: early diagnosis is key

Macrophage activation syndrome (MAS) is a life-threatening condition, and it is a subset of hemophagocytic lymphohistiocytosis (HLH). The clinical features include a persistent high-grade fever, hepatosplenomegaly, lymphadenopathy, hemorrhagic manifestations, and a sepsis-like condition. From the clinical features, it is usually difficult to differentiate between a true sepsis, disease flare-ups, or MAS. Although the laboratory abnormalities are similar to those of a disseminated intravascular coagulation, which shows pancytopenia, coagulopathy, hypofibrinogenemia, and an elevated d-dimer test, it can also be a late stage of MAS. Currently, MAS is still underrecognized and usually results in delayed in diagnosis, which leads to high morbidity and mortality. This literature review was conducted in the context of the clinical manifestations and the laboratory abnormalities in MAS, which might provide some clues for an early diagnosis. The best ways for an early recognition and a satisfactory diagnosis were based on the relative changes in the overall parameters from the baseline, together with a thorough and continuous physical examination for these kinds of patients. At present, diagnostic criteria have been proposed for HLH, MAS-associated systemic juvenile idiopathic arthritis, and an MAS-associated systemic lupus erythematosus. Therefore, selecting the proper diagnostic criteria for use is essential because not all of the criteria are suitable for every autoimmune disease.

A comprehensive review on adult onset Still's disease

Adult-onset Still's disease (AOSD) is a systemic inflammatory disorder of unknown etiology usually affecting young adults; spiking fever, arthritis and evanescent rash are commonly observed during the disease. Other frequently observed clinical features include sore throat, hepatomegaly, splenomegaly, lymphadenopathy and serositis. Furthermore, AOSD patients may experience different life-threating complications. Macrophage activation syndrome (MAS) has been reported up to 15% of AOSD patients and it is considered to be the most severe complication of the disease being characterised by high mortality rate. During AOSD, laboratory tests reflect the systemic inflammatory process showing high levels of erythrocyte sedimentation rate and C-reactive protein. In addition, the ferritin levels are typically higher than those observed in other autoimmune, inflammatory, infectious, or neoplastic diseases. Analysing AOSD disease course, 3 different clinical patterns of AOSD have been identified: i. monocyclic pattern, characterised by a systemic single episode; ii. polycyclic pattern, characterised by multiple, ≤ 1 year lasting, flares, alternating with remissions; iii. chronic pattern, related to a persistently active disease with associated polyarthritis. At present, AOSD therapeutic strategy is aimed at targeting pro-inflammatory signs and symptoms, preventing organ damage and life-threating complications and minimising adverse effects of treatment. However, the treatment of AOSD remains largely empirical, lacking controlled clinical trials. High dosages of corticosteroids are usually the first line therapy when the systemic symptoms predominate. Despite this treatment, a large percentage of patients experiences several flares with an evolution toward the chronic disease course and up to 16% of patients die during the follow up, due to AOSD-related complications. On these bases, in the last years, biological agents have been successfully used in refractory cases. Finally, multiple recent lines of evidence have suggested new insights in AOSD pathogenesis unmasking further therapeutic targets. In fact, small molecules, used in experimental MAS models, might represent new therapeutic options.

Effect of the anticoagulant, storage time and temperature of blood samples on the concentrations of 27 multiplex assayed cytokines - Consequences for defining reference values in healthy humans

Cytokines are potentially useful biomarkers of sepsis and other inflammatory conditions. Many cytokines can be released by leukocytes and platelets after sampling. The sampling and processing techniques are consequently critically important to measure the in vivo levels. We therefore examined the effects of four different anticoagulants, EDTA, citrate, lepirudin, heparin compared to serum, on the levels of 27 different cytokines. The effects of storage temperature, freezing and thawing on the plasma cytokines were examined. Cytokines were analysed using a multiplex immunoassay. The cytokine levels in serum were significantly higher compared with plasma, consistent with release of cytokines in vitro during coagulation. In general, the lowest values for all cytokines were found in EDTA samples, stored on crushed ice, centrifuged within 4h and thereafter stored at -80°C. MCP-1 and MIP-1β levels were highest in heparin plasma and storage of blood for up to 4h at room temperature significantly increased the interleukin (IL)-2, IL-6, IL-8, IFN-γ and GM-CSF levels in EDTA plasma, indicating post-sampling release. In contrast, the IP-10 levels were unaffected by sample storage at both temperatures. Our results indicate that the cytokines were more stable in plasma than in whole blood after sampling. Thus, cytokines should be analysed in EDTA plasma samples stored on ice and centrifuged within 4h. Based on these data, the reference ranges of 27 cytokines in EDTA plasma in 162 healthy human donors were calculated.

Treatment of adult-onset still's disease: up to date

INTRODUCTION

Adult onset Still's disease (AOSD) is a systemic inflammatory disorder of unknown etiology, and approximately 60-70% of patients may develop a chronic polyphasic form of the disease or a chronic polyarthritis. Due to rarity of disease, treatment of AOSD is not based on controlled study, but on case based experiences. Areas covered: Recently, the application of anti-cytokine therapy based on pathophysiology has resulted in significant progress in the treatment of AOSD. Here, we review current knowledge of the pathogenesis, disease progression, currently available biomarkers of disease activity, standard therapeutic agents, utility of biologic agents, future perspectives for treatment and treatment of macrophage activation syndrome. Expert commentary: Accumulated clinical data suggest that chronic disease can be classified into two subsets: dominant systemic disease, and the arthritis subgroup. IL-1 inhibitors may be more efficient for systemic manifestations and IL-6 inhibitor for both joint involvement and systemic manifestations. TNF inhibitors must be reserved for patients with purely chronic articular manifestations. For ideal management of patients, it is very important to measure disease activity accurately during follow up, but no single biomarker has been classified as ideal. New therapeutic agents and composite biomarkers are needed to improve the outcome of patients with AOSD by identifying disease activity properly.

Weathering the storm: Improving therapeutic interventions for cytokine storm syndromes by targeting disease pathogenesis

Cytokine storm syndromes require rapid diagnosis and treatment to limit the morbidity and mortality caused by the hyperinflammatory state that characterizes these devastating conditions. Herein, we discuss the current knowledge that guides our therapeutic decision-making and personalization of treatment for patients with cytokine storm syndromes. Firstly, ICU-level supportive care is often required to stabilize patients with fulminant disease while additional diagnostic evaluations proceed to determine the underlying cause of cytokine storm. Pharmacologic interventions should be focused on removing the inciting trigger of inflammation and initiation of an individualized immunosuppressive regimen when immune activation is central to the underlying disease pathophysiology. Monitoring for a clinical response is required to ensure that changes in the therapeutic regimen can be made as clinically warranted. Escalation of immunosuppression may be required if patients respond poorly to the initial therapeutic interventions, while a slow wean of immunosuppression in patients who improve can limit medication-related toxicities. In certain scenarios, a decision must be made whether an individual patient requires hematopoietic cell transplantation to prevent recurrence of disease. Despite these interventions, significant morbidity and mortality remains for cytokine storm patients. Therefore, we use this review to propose a clinical schema to guide current and future attempts to design rational therapeutic interventions for patients suffering from these devastating conditions, which we believe speeds the diagnosis of disease, limits medication-related toxicities, and improves clinical outcomes by targeting the heterogeneous and dynamic mechanisms driving disease in each individual patient.

Adult-onset Still's disease: Advances in the treatment

Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder mainly characterized by persistent high spiking fevers, evanescent rash, and joint involvement. The pathogenesis of AOSD is only partially known, but pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6, IL-18, and IFN-γ seem to play a major role in this disorder. AOSD is at the crossroad of auto-inflammatory syndromes and autoimmune diseases. It is diagnosed by exclusion to determine the presence of high serum ferritin levels, which is usually >1000 μg/L. AOSD is generally treated with non-steroidal anti-inflammatory drugs, corticosteroids, and disease-modifying anti-rheumatic drugs (DMARDs). Although information on biologic therapy in the management of AOSD is scarce, these drugs represent a major breakthrough in the management of patients with AOSD refractory to corticosteroids or conventional DMARDs or in patients presenting life-threatening manifestations. In this regard, TNF-α, IL-1, and IL-6 antagonists had been proved effective in patients with AOSD.

Prognostic factors of macrophage activation syndrome, at the time of diagnosis, in adult patients affected by autoimmune disease: Analysis of 41 cases collected in 2 rheumatologic centers

Macrophage activation syndrome (MAS) is a rare, life-threatening disease in which early diagnosis and aggressive therapeutic strategy may improve the outcome. Due to its rarity, epidemiologic data are still lacking. Hyperferritinemia is frequently associated with MAS and might modulate the cytokine storm, which is involved in the development of multiple organ failure. In this paper, we investigated clinical data, treatments, and outcome of a homogeneous cohort of 41 adult MAS patients, complicating autoimmune rheumatic diseases. MAS-related death occurred in 17 patients (42.5%) during the follow-up, and older age and increased serum ferritin levels, at the time of diagnosis, were significantly associated with mortality. In conclusion, adult MAS is associated with high mortality rate. Some clinical features at diagnosis may be predictive of MAS-associated death.

Successful Tocilizumab Therapy for Macrophage Activation Syndrome Associated with Adult-Onset Still's Disease: A Case-Based Review

We report the case of a 71-year-old Japanese woman with adult-onset Still's disease (AOSD) in whom macrophage activation syndrome (MAS) developed despite therapy with oral high-dose prednisolone and intravenous methylprednisolone pulse therapy twice. She was successfully treated with tocilizumab (TCZ). Soon afterward, her fever ceased and high levels of both ferritin and C-reactive protein levels decreased. Her course was complicated by disseminated intravascular coagulation, cytomegalovirus infection, and Pneumocystis jirovecii pneumonia. After these were resolved, AOSD-associated MAS was well controlled. She was discharged on hospital day 87. Although biologics such as TCZ are becoming established for the treatment of AOSD, there is no recommended therapy for AOSD-associated MAS. Several biologics have been tried for this complication, but their efficacy and safety remain controversial. We reviewed reported cases of AOSD-associated MAS successfully treated with various biologics. TCZ initiation after adequate nonselective immunosuppressive therapy, such as methylprednisolone pulse therapy or a prednisolone-based combination of immunosuppressants, can be an effective treatment for AOSD-associated MAS. On the other hand, biologics given after insufficient immunosuppressive therapy may cause MAS. A strategy combining adequate immunosuppression and a biologic could be safe if special attention is given to adverse events such as opportunistic infections or biologic-associated MAS.

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.

Janus kinase inhibition lessens inflammation and ameliorates disease in murine models of hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) comprises an emerging spectrum of inherited and noninherited disorders of the immune system characterized by the excessive production of cytokines, including interferon-γ and interleukins 2, 6, and 10 (IL-2, IL-6, and IL-10). The Janus kinases (JAKs) transduce signals initiated following engagement of specific receptors that bind a broad array of cytokines, including those overproduced in HLH. Based on the central role for cytokines in the pathogenesis of HLH, we sought to examine whether the inhibition of JAK function might lessen inflammation in murine models of the disease. Toward this end, we examined the effects of JAK inhibition using a model of primary (inherited) HLH in which perforin-deficient (Prf1(-∕-)) mice are infected with lymphocytic choriomeningitis virus (LCMV) and secondary (noninherited) HLH in which C57BL/6 mice receive repeated injections of CpG DNA. In both models, treatment with the JAK1/2 inhibitor ruxolitinib significantly lessened the clinical and laboratory manifestations of HLH, including weight loss, organomegaly, anemia, thrombocytopenia, hypercytokinemia, and tissue inflammation. Importantly, ruxolitinib treatment also significantly improved the survival of LCMV-infectedPrf1(-∕-)mice. Mechanistic studies revealed that in vivo exposure to ruxolitinib inhibited signal transducer and activation of transcription 1-dependent gene expression, limited CD8(+)T-cell expansion, and greatly reduced proinflammatory cytokine production, without effecting degranulation and cytotoxic function. Collectively, these findings highlight the JAKs as novel, druggable targets for mitigating the cytokine-driven hyperinflammation that occurs in HLH. These observations also support the incorporation of JAK inhibitors such as ruxolitinib into future clinical trials for patients with these life-threatening disorders.

Pathogenic Inflammation and Its Therapeutic Targeting in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE, lupus) is a highly complex and heterogeneous autoimmune disease that most often afflicts women in their child-bearing years. It is characterized by circulating self-reactive antibodies that deposit in tissues, including skin, kidneys, and brain, and the ensuing inflammatory response can lead to irreparable tissue damage. Over many years, clinical trials in SLE have focused on agents that control B- and T-lymphocyte activation, and, with the single exception of an agent known as belimumab which targets the B-cell survival factor BAFF, they have been disappointing. At present, standard therapy for SLE with mild disease is the agent hydroxychloroquine. During disease flares, steroids are often used, while the more severe manifestations with major organ involvement warrant potent, broad-spectrum immunosuppression with cyclophosphamide or mycophenolate. Current treatments have severe and dose-limiting toxicities and thus a more specific therapy targeting a causative factor or signaling pathway would be greatly beneficial in SLE treatment. Moreover, the ability to control inflammation alongside B-cell activation may be a superior approach for disease control. There has been a recent focus on the innate immune system and associated inflammation, which has uncovered key players in driving the pathogenesis of SLE. Delineating some of these intricate inflammatory mechanisms has been possible with studies using spontaneous mouse mutants and genetically engineered mice. These strains, to varying degrees, exhibit hallmarks of the human disease and therefore have been utilized to model human SLE and to test new drugs. Developing a better understanding of the initiation and perpetuation of disease in SLE may uncover suitable novel targets for therapeutic intervention. Here, we discuss the involvement of inflammation in SLE disease pathogenesis, with a focus on several key proinflammatory cytokines and myeloid growth factors, and review the known outcomes or the potential for targeting these factors in SLE.

Monocyte CD64 expression as a novel biomarker for the disease activity of systemic lupus erythematosus

Objective

Interferon alpha (IFN-α) is a key cytokine associated with systemic lupus erythematosus (SLE). IFN-α induces the expression of CD64 on monocytes (mCD64). Although enhanced mCD64 expression has been reported in patients with SLE, it has never been assessed quantitatively. The aim of this study was to investigate whether or not mCD64 expression correlates with SLE disease activity.

Methods

The mCD64 expression levels were assessed quantitatively in 40 patients with active or inactive SLE by using flow cytometry. The mCD64 expression levels were subsequently compared with the SLE disease activity index (SLEDAI) and levels of existing SLE activity biomarkers, such as anti-DNA antibody, complements, and so on.

Results

The mCD64 expression was significantly higher in active disease than in inactive disease SLE (median molecules/cell, interquartile range: 34,648, 8174–24,932 and 20,865, 6357–21,503, respectively; p < 0.001). The levels of mCD64 expression strongly correlated with SLEDAI ( r = 0.68, p < 0.001).

Conclusion

The mCD64 expression is a simple and useful biomarker for evaluating disease activity in patients with SLE.

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.

Increased level of H-ferritin and its imbalance with L-ferritin, in bone marrow and liver of patients with adult onset Still's disease, developing macrophage activation syndrome, correlate with the severity of the disease

In this paper, we aimed to evaluate the levels of ferritin enriched in H subunits (H-ferritin) and ferritin enriched in L subunits (L-ferritin) and the cells expressing these 2 molecules, in the bone marrow (BM) and liver biopsies obtained from adult onset Still's disease (AOSD) patients who developed macrophage activation syndrome (MAS), and correlating these data with the severity of the disease. Twenty-one patients with MAS-associated AOSD underwent BM biopsy and among them, 9 patients with hepatomegaly and elevated liver enzymes underwent liver biopsy. All the samples were stained by both immunohistochemistry and immunofluorescence. A statistical analysis was performed to estimate the possible correlation among both H-ferritin and L-ferritin tissue expression and the clinical picture of the disease. Furthermore, the same analysis was performed to evaluate the possible correlation among the number of CD68/H-ferritin or CD68/L-ferritin positive cells and the clinical picture. Both immunohistochemical and immunofluorescence analysis demonstrated an increased tissue H-ferritin expression, in the BM and liver samples of our patients. This increased expression correlated with the severity of the disease. An inflammatory infiltrate, enriched in CD68 macrophages, expressing H-ferritin was observed in both the BM and the liver samples of our patients. Furthermore, we observed, that this increased number of CD68/H-ferritin positive cells significantly correlated with the severity of clinical picture and this specific BM infiltrate correlated with the mortality rate, reported in our cohort. Our data showed an imbalance between the levels of H- and L-ferritin in different organs of patients with MAS-associated AOSD and the evidence of a strong infiltrate of CD68/H-ferritin positive cells in the same organs. Furthermore, a strong correlation among both the tissue H-ferritin and the CD68/H-ferritin positive cells and the clinical picture was observed.

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

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

Hemophagocytic syndrome and inflammatory myopathy with abundant macrophages in a patient with adult-onset Still's disease

We herein describe a 71-year-old woman with adult-onset Still's disease (AOSD) who developed fever, myalgia, and pancytopenia. The bone marrow aspiration and muscle biopsy revealed hemophagocytic syndrome (HPS) and inflammatory myopathy with abundant macrophages (IMAM). Immunostained specimens were positive for expression of retinoic acid-inducible gene-I (RIG-I), which recognizes viral RNA in infiltrated mononuclear cells as well as muscle tissues. These findings suggest that RIG-I may be involved in induction of HPS and IMAM in AOSD.

Adult onset Still's disease (AOSD) in the era of biologic therapies: dichotomous view for cytokine and clinical expressions

Adult onset Still's disease (AOSD) is a rare inflammatory disorder characterized by hectic spiking fever, evanescent rash and joint involvement. Prognosis is highly variable upon disease course and specific involvements, ranging from benign and limited outcome to chronic destructive polyarthritis and/or life-threatening events in case of visceral complications or reactive hemophagocytic lymphohistiocytosis (RHL). AOSD remains a debatable entity at the frontiers of autoimmune diseases and autoinflammatory disorders. The pivotal role of macrophage cell activation leading to a typical Th1 cytokine storm is now well established in AOSD, and confirmed by the benefits using treatments targeting TNF-α, IL-1β or IL-6 in refractory patients. However, it remains difficult to determine predictive factors of outcome and to draw guidelines for patient management. Herein, reviewing literature and relying on our experience in a series of 8 refractory AOSD patients, we question nosology and postulate that different cytokine patterns could underlie contrasting clinical expressions, as well as responses to targeted therapies. We therefore propose to dichotomize AOSD according to its clinical presentation. On the one hand, 'systemic AOSD' patients, exhibiting the highest inflammation process driven by excessive IL-18, IL-1β and IL-6 production, would be at risk of life-threatening complications (such as multivisceral involvements and RHL), and would preferentially respond to IL-1β and IL-6 antagonists. On the other hand, 'rheumatic AOSD' patients, exhibiting pre-eminence of joint involvement driven by IL-8 and IFN-γ production, would be at risk of articular destructions, and would preferentially respond to TNF-α blockers.