Ferritin triggers neutrophil extracellular trap-mediated cytokine storm through Msr1 contributing to adult-onset Still's disease pathogenesis

PAI-1 Deficiency Promotes NET-mediated Pyroptosis and Ferroptosis during Pseudomonas Aeruginosa-induced Acute Lung Injury by Regulating the PI3K/MAPK/AKT Axis

Circulating neutrophil extracellular trap (NET) formation is an adaptive process during acute lung injury (ALI). The important role of plasminogen activator inhibitor (PAI)-1 in NET formation during ALI remains unclear. This research intends to examine the impacts of the decrease in PAI-1 levels on NET formation and the underlying mechanism. We found a relative association between the increase in plasma NET levels and thromboinflammation-induced lung damage in patients with ARDS. PAI-1 knockout (KO) mice exhibited significant increases in Pseudomonas aeruginosa (PAO1 strain)-induced ALI, inflammation, inflammatory cell accumulation, and proinflammatory cytokine secretion, and wild-type mice exhibited the opposite changes. During PAO1-induced ALI, PAI-1 KO increased NET release and the levels of prothrombotic markers in mice. PAI-1 deficiency also promoted NET formation and NET-mediated pyroptosis and ferroptosis by activating the PI3K/MAPK/AKT pathway in a PAO1-induced ALI mouse model. In conclusion, PAI-1 KO exacerbated PAO1-induced pneumonia-associated injury and contributed to NET-mediated pyroptosis and ferroptosis through PI3K/MAPK/AKT pathway activation. Thus, targeting PAI-1 and NETs may be a promising therapeutic approach for ameliorating pneumonia and thromboinflammation-associated ALI.

Extracellular vesicles-derived ferritin from lipid-induced hepatocytes regulates activation of hepatic stellate cells

Introduction

and objectives: Extracellular vesicles (EVs) have emerged as key players in intercellular communication within the context of non-alcoholic fatty liver disease (NAFLD). This study aims to explore the intricate crosstalk between hepatocytes and hepatic stellate cells (HSCs) mediated by EVs in NAFLD.

Materials and methods

EVs ferritin was detected in hepatocytes stimulated with free fatty acids (FFA) as well as in NAFLD mice. Deferoxamine (DFO) was employed to reduce ferritin levels, while GW4869 was utilized to inhibit EVs. The impact of EVs ferritin on the HSCs activation was evaluated both in vitro and in vivo. Additionally, serum EVs ferritin levels were compared between NAFLD patients and controls.

Results

FFA treatment induces the formation and secretion of EVs and facilitates the release of ferritin from hepatocytes via EVs. Subsequently, EVs ferritin is hijacked by HSCs, prompting accelerated HSCs activation. Silencing ferritin with DFO and inhibiting EVs formation and secretion with GW4869 can reverse the effects of FFA treatment and disrupt the communication between hepatocytes and HSCs. Accumulation of ferritin leads to excessive reactive oxygen species (ROS) production, promoting HSCs fibrogenesis. Conversely, depleting EVs ferritin cargo restores liver function, concurrently mitigating NAFLD-associated fibrosis. Notably, NAFLD patients exhibit significantly elevated levels of serum EVs ferritin.

Conclusions

This study unveils a previously underestimated role of ferritin in HSCs upon its release from hepatocytes, emphasizing DFO as a promising compound to impede NAFLD advancement.

The Systemic Score May Identify Life-Threatening Evolution in Still Disease: Data from the GIRRCS AOSD-Study Group and the AIDA Network Still Disease Registry

OBJECTIVE

We aimed to evaluate the clinical usefulness of the systemic score in the prediction of life-threatening evolution in Still disease. We also aimed to assess the clinical relevance of each component of the systemic score in predicting life-threatening evolution and to derive patient subsets accordingly.

METHODS

A multicenter, observational, prospective study was designed including patients included in the Gruppo Italiano Di Ricerca in Reumatologia Clinica e Sperimentale Adult-Onset Still Disease Study Group and the Autoinflammatory Disease Alliance Network Still Disease Registry. Patients were assessed to see if the variables to derive the systemic score were available. The life-threatening evolution was defined as mortality, whatever the clinical course, and/or macrophage activation syndrome, a secondary hemophagocytic lymphohistiocytosis associated with a poor prognosis.

RESULTS

A total of 597 patients with Still disease were assessed (mean ± SD age 36.6 ± 17.3 years; male 44.4%). The systemic score, assessed as a continuous variable, significantly predicted the life-threatening evolution (odds ratio [OR] 1.24; 95% confidence interval [CI] 1.07-1.42; P = 0.004). A systemic score ≥7 also significantly predicted the likelihood of a patient experiencing life-threatening evolution (OR 3.36; 95% CI 1.81-6.25; P < 0.001). Assessing the clinical relevance of each component of the systemic score, liver involvement (OR 1.68; 95% CI 1.48-2.67; P = 0.031) and lung disease (OR 2.12; 95% CI 1.14-4.49; P = 0.042) both significantly predicted life-threatening evolution. The clinical characteristics of patients with liver involvement and lung disease were derived, highlighting their relevance in multiorgan disease manifestations.

CONCLUSION

The clinical utility of the systemic score was shown in identifying Still disease at a higher risk of life-threatening evolution in a large cohort. Furthermore, the clinical relevance of liver involvement and lung disease was highlighted.

The landscape of innate and adaptive immune cell subsets in patients with adult-onset Still's disease

OBJECTIVE

Adult-onset Still's disease (AOSD) is a systemic autoinflammatory disorder. The understanding of the changes in adaptive immune cells and the crosstalk between innate and adaptive immune systems in AOSD is limited. This study aimed to examine the peripheral immune cell composition and inflammatory protein levels in AOSD patients.

METHODS

Twenty-nine active AOSD patients were enrolled. Flow cytometry was used to analyse the cell populations in peripheral blood. Antibody chips were utilized to detect the protein expression profile in serum.

RESULTS

In active AOSD patients, there was an increase in the percentage of classical and non-classical monocytes among peripheral blood mononuclear cells. The proportion of natural killer (NK) cells decreased, with an increase in CD56dim NK1 cells and a decrease in CD56bright NK2 cells compared with healthy controls (HCs). The percentage of naïve central memory T cells was decreased, while the percentage of effector and effector memory T cells was increased among adaptive lymphocytes. The proportion of naïve B and memory B cells was decreased, while plasma cells were increased in AOSD patients, indicating activation of the adaptive immune system. Additionally, the serum levels of 40 proteins were elevated in AOSD patients, primarily involved in cytokine-cytokine receptor interaction, inflammatory response and regulation of mitogen-activated protein kinase cascade.

CONCLUSION

Our findings showed the activation of the innate and adaptive immune system in AOSD. The protein-protein interaction analysis suggested potential communication between innate and adaptive cell subsets. These findings provide new insights into the pathogenesis of the disease and the development of targeted therapies.

Neutrophil activation biomarker pentraxin 3 for diagnosis and monitoring of macrophage activation syndrome occurrence in adult-onset Still's disease

Macrophage activation syndrome (MAS) is a potentially fatal consequence of adult-onset Still's disease (AOSD), driven by a cytokine storm. Efficient early diagnosis of AOSD-associated MAS requires a sensitive and specific biomarker. In this study, we demonstrated that pentraxin 3 (PTX3), an acute phase protein, was associated with AOSD disease activity and served as a biomarker for AOSD-MAS. PTX3 levels were significantly increased in AOSD patients compared to other autoimmune diseases and healthy controls. Plasma PTX3 levels showed positive correlations with inflammatory markers, the systemic score and the HScore. In active AOSD with MAS, PTX3 levels were higher compared to those in non-AOSD haemophagocytic lymphohistiocytosis (HLH) patients. Moreover, the PTX3's area under the curve value for distinguishing AOSD with MAS exceeded that of soluble interleukin-2 receptor, ferritin and C-reactive protein. Furthermore, plasma levels of PTX3 were associated with circulating NET-DNA levels. To fully understand the underlying mechanism of PTX3 prompting AOSD and AOSD-MAS progression, we discovered that neutrophils exhibited enhanced NET formation and mitogen-activated protein kinases (MAPK) pathway activation upon PTX3 stimulation. More importantly, PTX3-induced NET formation was effectively dampened by MAPK pathway inhibitors. These findings collectively revealed that PTX3 has a favorable correlation with disease activity and may serve as a potential biomarker to differentiate AOSD patients with MAS. Additionally, PTX3 induces NET release via the MAPK pathway, suggesting a pathogenic role in AOSD-MAS.

Tackling Severe Neutrophilic Inflammation in Airway Disorders with Functionalized Nanosheets

Severe airway inflammatory disorders impose a significant societal burden, and the available treatments are unsatisfactory. High levels of neutrophil extracellular trap (NET) and cell-free DNA (cfDNA) were detected in the inflammatory microenvironment of these diseases, which are closely associated with persistent uncontrolled neutrophilic inflammation. Although DNase has proven to be effective in mitigating neutrophilic airway inflammation in mice by reducing cfDNA and NET levels, its clinical use is hindered by severe side effects. Here, we synthesized polyglycerol-amine (PGA) with a series of hydroxyl/amine ratios and covered them with black phosphorus (BP) nanosheets. The BP nanosheets functionalized with polyglycerol-50% amine (BP-PGA50) efficiently lowered cfDNA levels, suppressed toll-like receptor 9 (TLR9) activation and inhibited NET formation in vitro. Importantly, BP-PGA50 nanosheets demonstrated substantial accumulation in inflamed airway tissues, excellent biocompatibility, and potent inflammation modulation ability in model mice. The 2D sheet-like structure of BP-PGA50 was identified as a crucial factor for the therapeutic efficacy, and the hydroxyl/amine ratio was revealed as a significant parameter to regulate the protein resistance, cfDNA-binding efficacy, and cytotoxicity. This study shows the promise of the BP-PGA50 nanosheet for tackling uncontrolled airway inflammation, which is also significant for the treatment of other neutrophilic inflammatory diseases. In addition, our work also highlights the importance of proper surface functionalization, such as hydroxyl/amine ratio, in therapeutic nanoplatform construction for inflammation modulation.

Recent advances on neutrophil dysregulation in the pathogenesis of rheumatic diseases

PURPOSE OF REVIEW

The exact pathogenic mechanisms of rheumatic diseases (RMD) remain largely unknown. Increasing evidence highlights a pathogenic role of neutrophil dysregulation in the development of RMD.

RECENT FINDINGS

The purpose of this review is to present a current overview of recent advancements in understanding the role of neutrophil dysfunction in the development of RMD. Additionally, this review will discuss strategies for targeting pathways associated with neutrophil dysregulation as potential treatments for RMD. One specific aspect of neutrophil dysregulation, known as neutrophil extracellular traps (NETs), will be explored. NETs have been found to contribute to chronic pulmonary inflammation and fibrosis, as well as serve as DNA scaffolds for binding autoantigens, including both citrullinated and carbamylated autoantigens. Putative therapies, such as 6-gingerol or defibrotide, have demonstrated beneficial effects in the treatment of RMD by suppressing NETs formation.

SUMMARY

Recent advances have significantly reinforced the crucial role of neutrophil dysregulation in the pathogenesis of RMD. A deeper understanding of the potential mechanisms underlying this pathogenic process would aid in the development of more precise and effective targeting strategies, thus ultimately improving the outcomes of RMD.

Prognostic value of preoperative serum ferritin in hepatocellular carcinoma patients undergoing transarterial chemoembolization

The present study investigated the prognostic impact of preoperative serum ferritin (SF) levels on the survival of patients with hepatocellular carcinoma (HCC) undergoing transarterial chemoembolization (TACE). Clinicopathological characteristics and laboratory biomarkers of 223 patients with HCC who underwent TACE were retrospectively reviewed. The Kaplan-Meier method was used to calculate the overall survival (OS), and the log-rank test was used to evaluate statistical significance. Univariate and multivariate analyses were performed using Cox proportional hazards regression to evaluate the prognostic impact of SF in these patients. The present findings identified extrahepatic metastases [hazard ratio (HR)=0.490,95%; confidence interval (CI)=0.282-0.843; P=0.010)] and vascular invasion (HR=0.373; 95% CI=0.225-0.619; P<0.0001) as independent prognostic factors for OS. However, preoperative SF levels could not independently predict OS when compared with other prognostic factors (HR=0.810; 95% CI=0.539-1.216; P=0.309). In conclusion, preoperative SF level is an unreliable biochemical predictor of survival in patients with HCC undergoing TACE.

Elevated ferritin, mediated by IL-18 is associated with systemic inflammation and mortality in acute respiratory distress syndrome (ARDS)

BACKGROUND

Inflammatory subphenotypes have been identified in acute respiratory distress syndrome (ARDS). Hyperferritinaemia in sepsis is associated with hyperinflammation, worse clinical outcomes, and may predict benefit with immunomodulation. Our aim was to determine if raised ferritin identified a subphenotype in patients with ARDS.

METHODS

Baseline plasma ferritin concentrations were measured in patients with ARDS from two randomised controlled trials of simvastatin (Hydroxymethylglutaryl-CoA Reductase Inhibition with Simvastatin in Acute Lung Injury to Reduce Pulmonary Dysfunction-2 (HARP-2); discovery cohort, UK) and neuromuscular blockade (ROSE; validation cohort, USA). Results were analysed using a logistic regression model with restricted cubic splines, to determine the ferritin threshold associated with 28-day mortality.

RESULTS

Ferritin was measured in 511 patients from HARP-2 (95% of patients enrolled) and 847 patients (84% of patients enrolled) from ROSE. Ferritin was consistently associated with 28-day mortality in both studies and following a meta-analysis, a log-fold increase in ferritin was associated with an OR 1.71 (95% CI 1.01 to 2.90) for 28-day mortality. Patients with ferritin >1380 ng/mL (HARP-2 28%, ROSE 24%) had a significantly higher 28-day mortality and fewer ventilator-free days in both studies. Mediation analysis, including confounders (acute physiology and chronic health evaluation-II score and ARDS aetiology) demonstrated a statistically significant contribution of interleukin (IL)-18 as an intermediate pathway between ferritin and mortality.

CONCLUSIONS

Ferritin is a clinically useful biomarker in ARDS and is associated with worse patient outcomes. These results provide support for prospective interventional trials of immunomodulatory agents targeting IL-18 in this hyperferritinaemic subgroup of patients with ARDS.

Ferritin-mediated neutrophil extracellular traps formation and cytokine storm via macrophage scavenger receptor in sepsis-associated lung injury

BACKGROUND

Sepsis is a severe systemic inflammatory disorder manifested by a dysregulated immune response to infection and multi-organ failure. Numerous studies have shown that elevated ferritin levels exist as an essential feature during sepsis and are able to suggest patients' prognoses. At the same time, the specific mechanism of ferritin-induced inflammatory injury remains unclear.

METHODS

Hyper-ferritin state during inflammation was performed by injecting ferritin into a mouse model and demonstrated that injection of ferritin could induce a systemic inflammatory response and increase neutrophil extracellular trap (NET) formation.Padi4-/-, Elane-/- and Cybb-/- mice were used for the NETs formation experiment. Western blot, immunofluorescence, ELISA, and flow cytometry examined the changes in NETs, inflammation, and related signaling pathways.

RESULTS

Ferritin induces NET formation in a peptidylarginine deiminase 4 (PAD4), neutrophil elastase (NE), and reactive oxygen species (ROS)-dependent manner, thereby exacerbating the inflammatory response. Mechanistically, ferritin induces the expression of neutrophil macrophage scavenger receptor (MSR), which promotes the formation of NETs. Clinically, high levels of ferritin in patients with severe sepsis correlate with NETs-mediated cytokines storm and are proportional to the severity of sepsis-induced lung injury.

CONCLUSIONS

In conclusion, we demonstrated that hyper-ferritin can induce systemic inflammation and increase NET formation in an MSR-dependent manner. This process relies on PAD4, NE, and ROS, further aggravating acute lung injury. In the clinic, high serum ferritin levels are associated with elevated NETs and worse lung injury, which suggests a poor prognosis for patients with sepsis. Our study indicated that targeting NETs or MSR could be a potential treatment to alleviate lung damage and systemic inflammation during sepsis. Video Abstract.

Mechanisms controlling cellular and systemic iron homeostasis

In mammals, hundreds of proteins use iron in a multitude of cellular functions, including vital processes such as mitochondrial respiration, gene regulation and DNA synthesis or repair. Highly orchestrated regulatory systems control cellular and systemic iron fluxes ensuring sufficient iron delivery to target proteins is maintained, while limiting its potentially deleterious effects in iron-mediated oxidative cell damage and ferroptosis. In this Review, we discuss how cells acquire, traffick and export iron and how stored iron is mobilized for iron-sulfur cluster and haem biogenesis. Furthermore, we describe how these cellular processes are fine-tuned by the combination of various sensory and regulatory systems, such as the iron-regulatory protein (IRP)-iron-responsive element (IRE) network, the nuclear receptor co-activator 4 (NCOA4)-mediated ferritinophagy pathway, the prolyl hydroxylase domain (PHD)-hypoxia-inducible factor (HIF) axis or the nuclear factor erythroid 2-related factor 2 (NRF2) regulatory hub. We further describe how these pathways interact with systemic iron homeostasis control through the hepcidin-ferroportin axis to ensure appropriate iron fluxes. This knowledge is key for the identification of novel therapeutic opportunities to prevent diseases of cellular and/or systemic iron mismanagement.

Characteristics of COVID-19 and Impact of Disease Activity in Patients with Adult-Onset Still's Disease

INTRODUCTION

This study aimed to characterize the morbidity, hospitalization, and mortality rates among patients with adult-onset Still's disease (AOSD) affected by coronavirus disease 2019 (COVID-19) and explore the impact of COVID-19 on the disease activity of AOSD.

METHODS

Data on the clinical and demographic characteristics, COVID-19-related symptoms, and outcomes were retrospectively collected. Patients were stratified according to COVID-19 severity and associations between risk factors and outcomes were analyzed using multivariate logistic regression. The disease activity of patients with AOSD flares after COVID-19 was described.

RESULTS

A total of 188 patients with AOSD were followed up, of whom 75.5% (n = 142) had a confirmed or highly suspected COVID-19. Patients on medium or high-dose oral glucocorticoids or Janus kinase (JAK) inhibitors were at increased risk of developing moderate to severe COVID-19. Six patients suffered flares of AOSD following COVID-19 in a short period; however, the relapse rate was not statistically increased compared with patients without COVID-19.

CONCLUSION

Patients with AOSD receiving medium or high-dose glucocorticoid therapy or JAK inhibitors had worse COVID-19 outcomes. Further work is needed to explore risk factors affecting COVID-19 outcomes and the impact of COVID-19 on disease activity in AOSD.

Recent advances and evolving concepts in Still's disease

Still's disease is a rare inflammatory syndrome that encompasses systemic juvenile idiopathic arthritis and adult-onset Still's disease, both of which can exhibit life-threatening complications, including macrophage activation syndrome (MAS), a secondary form of haemophagocytic lymphohistiocytosis. Genetic insights into Still's disease involve both HLA and non-HLA susceptibility genes, suggesting the involvement of adaptive immune cell-mediated immunity. At the same time, phenotypic evidence indicates the involvement of autoinflammatory processes. Evidence also implicates the type I interferon signature, mechanistic target of rapamycin complex 1 signalling and ferritin in the pathogenesis of Still's disease and MAS. Pathological entities associated with Still's disease include lung disease that could be associated with biologic DMARDs and with the occurrence of MAS. Historically, monophasic, recurrent and persistent Still's disease courses were recognized. Newer proposals of alternative Still's disease clusters could enable better dissection of clinical heterogeneity on the basis of immune cell profiles that could represent diverse endotypes or phases of disease activity. Therapeutically, data on IL-1 and IL-6 antagonism and Janus kinase inhibition suggest the importance of early administration in Still's disease. Furthermore, there is evidence that patients who develop MAS can be treated with IFNγ antagonism. Despite these developments, unmet needs remain that can form the basis for the design of future studies leading to improvement of disease management.

The latest advances in the use of biological DMARDs to treat Still's disease

INTRODUCTION

Currently, the therapeutic management of Still's disease, a multisystemic inflammatory rare disorder, is directed to target the inflammatory symptoms and signs of patients. The treatment varies from glucocorticoids to disease-modifying antirheumatic drugs (DMARDs), both conventional synthetic and biological (bDMARDs). Usually, in refractory patients, bDMARDs are administered.

AREAS COVERED

Among bDMARDs, IL-1 and IL-6 inhibitors are frequently used, as data reported from both clinical trials and 'real-life' experiences. Recently, innovative therapeutic strategies have suggested an early administration of bDMARDs to increase the rate of clinical response and drug-free remission. Some new targets have been also proposed targeting IL-18, IFN-γ, and JAK/STAT pathway, which could be applied to Still's disease and its life-threatening evolution.

EXPERT OPINION

Many lines of evidence improved the knowledge about the therapeutic management of Still's disease with bDMARDs. However, many unmet needs may be still highlighted which could provide the basis to arrange further specific research in increasing the rate of clinical response. In fact, Still's disease remains a highly heterogeneous disease suggesting possible diverse underlying pathogenic mechanisms, at least partially, and consequent different therapeutic strategies. A better patient stratification may help in arranging specific studies to improve the long-term outcome of Still's disease.

Neutrophil extracellular trap-induced intermediate monocytes trigger macrophage activation syndrome in adult-onset Still's disease

BACKGROUND

Adult-onset Still's disease (AOSD) is a systemic autoinflammatory disease characterized by innate immune system activation, with a high risk for macrophage activation syndrome (MAS). MAS development is associated with monocyte/macrophage activation and cytokine storm. Monocytes consist of three different subsets, classical monocytes (CMs, CD14brightCD16 -), intermediate monocytes (IMs, CD14brightCD16 +), and non-classical monocytes (NCMs, CD14dimCD16 +), each has distinct roles in inflammatory regulation. However, the frequencies and regulatory mechanism of monocyte subsets in AOSD patients have not been identified.

METHODS

We performed flow cytometry, RNA sequencing, phagocytosis analysis, and enzyme-linked immunosorbent assay to evaluate monocyte subsets, cell functions, and potential biomarkers. The effect of neutrophil extracellular traps (NETs) on monocytes was determined by evaluating mRNA levels of DNA sensors, surface CD16 expression, and inflammasome pathway activation.

RESULTS

Higher proportions of intermediate monocytes (IMs) were identified in active AOSD patients. IMs displayed higher expression of CD80, CD86, HLA-DR, and CD163 than CMs and NCMs. CD163 upregulation was noted on AOSD IMs, accompanied by increased phagocytic activity and elevated cytokine/chemokine production, including IL-1β, IL-6, CCL8, and CXCL10. The frequencies of IMs were correlated with disease activity and higher in AOSD patients with MAS (AOSD-MAS). CCL8 and CXCL10 were highly expressed in RNA sequencing of monocytes from AOSD-MAS patients and plasma CXCL10 level could serve as a potential biomarker for AOSD-MAS. Moreover, DNA-sensing pathway was activated in monocytes from AOSD-MAS patients. Stimulation with NETs derived from AOSD induced DNA sensor expression, the expansion of IMs, and inflammasome pathway activation. These effects can be abrogated by DNase I treatment.

CONCLUSIONS

Our results demonstrated that the proportions of IMs were elevated in AOSD and associated with MAS. The DNA component in NETs from AOSD plays an important role in the formation of IMs, shedding new light for the therapeutic target.

Functional immunophenotyping of blood neutrophils identifies novel endotypes of viral response in preschool children with recurrent wheezing

BACKGROUND

Preschool children with recurrent wheezing are heterogeneous, with differing responses to respiratory viral infections. Although neutrophils are crucial for host defense, their function has not been studied in this population.

OBJECTIVE

We performed functional immunophenotyping on isolated blood neutrophils from 52 preschool children with recurrent wheezing (aeroallergen sensitization, n = 16; no sensitization, n = 36).

METHODS

Blood neutrophils were purified and cultured overnight with polyinosinic:polycytidylic acid [poly(I:C)] as a viral analog stimulus. Neutrophils underwent next-generation sequencing with Reactome pathway analysis and were analyzed for cytokine secretion, apoptosis, myeloperoxidase, and extracellular DNA release. CD14+ monocytes were also exposed to neutrophil culture supernatant and analyzed for markers of M1 and M2 activation.

RESULTS

A total of 495 genes, related largely to the innate immune system and neutrophil degranulation, were differently expressed in children with versus without aeroallergen sensitization. Functional experiments identified more neutrophil degranulation and extracellular trap formation (ie, more myeloperoxidase and extracellular DNA) and less neutrophil proinflammatory cytokine secretion in children with aeroallergen sensitization. Neutrophils also shifted CD14+ monocytes to a more anti-inflammatory (ie, M2) phenotype in sensitized children and a more proinflammatory (ie, M1) phenotype in nonsensitized children. Although both groups experienced viral exacerbations, annualized exacerbation rates prompting unscheduled health care were also higher in children without aeroallergen sensitization after enrollment.

CONCLUSIONS

Systemic neutrophil responses to viral infection differ by allergic phenotype and may be less effective in preschool children without allergic inflammation. Further studies of neutrophil function are needed in this population, which often has less favorable therapeutic responses to inhaled corticosteroids and other therapies directed at type 2-high inflammation.

Risk of Macrophage Activation Syndrome in Patients with Adult-Onset Still's Disease Treated with IL-1 and IL-6 Inhibitors: A Meta-analysis and Single-Center Experience

INTRODUCTION

Patients with adult-onset Still's disease (AOSD) are at risk of developing macrophage activation syndrome (MAS), a life-threatening condition. Some cases of MAS have been reported following the use of biological agents, highlighting the need to identify contributing factors. This study aims to examine the characteristics of MAS in patients with AOSD treated with anakinra (ANA) or tocilizumab (TCZ).

METHODS

A systematic search was conducted across four online databases to identify studies reporting the incidence rates of MAS in patients with AOSD treated with ANA or TCZ. Meta-analysis was performed using a random-effects model and the generic inverse variance method to estimate the pooled incidence rates. The difference in incidence rates of MAS between TCZ and ANA was assessed. Additionally, we analyzed laboratory data and clinical features of AOSD cases at our institution, stratifying them into two groups: those who developed MAS after TCZ administration and those who did not.

RESULTS

Of the 455 screened articles, we included five ANA and six TCZ studies. The pooled incidence rates of MAS were 1.50% (95% confidence interval [CI], 0-3.36) for ANA (345 patients) and 14.01% (95% CI 4.51-23.51) for TCZ (94 patients). MAS incidence was significantly higher in the TCZ group (P = 0.01). Among the 17 patients from our institution, the six patients who developed MAS had significantly higher white blood cell and neutrophil counts, as well as elevated levels of lactate dehydrogenase, C-reactive protein, and ferritin before TCZ induction (P < 0.05).

CONCLUSIONS

In patients with AOSD, the manifestation of MAS is influenced by multiple causative factors. Consequently, the administration of TCZ should be approached with caution, particularly in patients exhibiting elevated inflammatory markers.

TRIAL REGISTRATION

This study was registered with the Clinical Trial Registry of the University Hospital Medical Information Network (Japan) as UMIN000049243.

New Perspectives on Circulating Ferritin: Its Role in Health and Disease

The diagnosis of iron disturbances usually includes the evaluation of serum parameters. Serum iron is assumed to be entirely bound to transferrin, and transferrin saturation-the ratio between the serum iron concentration and serum transferrin-usually reflects iron availability. Additionally, serum ferritin is commonly used as a surrogate of tissue iron levels. Low serum ferritin values are interpreted as a sign of iron deficiency, and high values are the main indicator of pathological iron overload. However, in situations of inflammation, serum ferritin levels may be very high, independently of tissue iron levels. This presents a particularly puzzling challenge for the clinician evaluating the overall iron status of the patient in the presence of an inflammatory condition. The increase in serum ferritin during inflammation is one of the enigmas regarding iron metabolism. Neither the origin, the mechanism of release, nor the effects of serum ferritin are known. The use of serum ferritin as a biomarker of disease has been rising, and it has become increasingly diverse, but whether or not it contributes to controlling the disease or host pathology, and how it would do it, are important, open questions. These will be discussed here, where we spotlight circulating ferritin and revise the recent clinical and preclinical data regarding its role in health and disease.

Genetically Engineered Cellular Nanovesicle as Targeted DNase I Delivery System for the Clearance of Neutrophil Extracellular Traps in Acute Lung Injury

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are prevalent critical illnesses with a high mortality rate among patients in intensive care units. Neutrophil extracellular traps (NETs) are implicated in the pathogenesis of ALI/ARDS and represent a promising therapeutic target. However, the clinical application of deoxyribonuclease I (DNase I), the only drug currently available to clear NETs, is limited due to the lack of precise and efficient delivery strategies. Therefore, targeted delivery of DNase I to the inflamed lung remains a critical issue to be addressed. Herein, a novel biomimetic DNase I delivery system is developed (DCNV) that employs genetically and bioorthogonally engineered cellular nanovesicles for pulmonary NETs clearance. The CXC motif chemokine receptor 2 overexpressed cellular nanovesicles can mimic the inflammatory chemotaxis of neutrophils in ALI/ARDS, leading to enhanced lung accumulation. Furthermore, DNase I immobilized through bioorthogonal chemistry exhibits remarkable enzymatic activity in NETs degradation, thus restraining inflammation and safeguarding lung tissue in the lipopolysaccharide-induced ALI murine model. Collectively, the findings present a groundbreaking proof-of-concept in the utilization of biomimetic cellular nanovesicles to deliver DNase I for treating ALI/ARDS. This innovative strategy may usher in a new era in the development of pharmacological interventions for various inflammation-related diseases.

[Update on Adult-Onset Still's Disease: Diagnosis, Therapy and Guideline]

Adult-onset Still's disease (ASOD) is an autoinflammatory disease of unknown etiology which is pathogenetically characterized by an involvement of the innate immune response with activation of neutrophils and an increased secretion of IL-1, IL-6, IL-18, type 1 interferons. Still's disease may occur at any age with distinct variability in signs and symptoms. Recently, the German Society of Rheumatology (DGRh) has issued an AOSD guideline which recommends diagnosing AOSD based on a characteristic combination of symptoms including intermittent fever, rash, arthralgia, and arthritis after exclusion of infections, neoplasms and other rheumatological conditions. Classification criteria according to Yamaguchi may support the clinical diagnosis. Therapy is recommended to include glucocorticosteroids and methotrexate or ciclosporin, at higher activity levels IL1-receptor antagonist anakinra, IL-1β antibody canakinumab, or IL6-receptor antibody tocilizumab. At a high disease activity, anakinra or canakinumab may be employed primarily. Local drug licensing policies may have to be considered, as these substances are not universally approved in these scenarios. Important complications to consider consist in perimyocarditis, a multi-faceted pulmonary involvement, and macrophage activation syndrome (MAS). MAS features multi-organ involvement and cytopenias. Besides supportive measures often requiring intensive care, high dose glucocorticosteroids as well as above named biologics, and if necessary, also etoposide based therapeutic regimen are used.

The similar expression of both ferritin and scavenger receptors activation genes in patients with COVID19 and AOSD support their role in the pathogenesis of these diseases and identify a common mechanism at the basis of the "hyperferritinemic syndromes"

A role for COVID19 in "hyperferritinemic syndromes" has been proposed based on its clinical and serological characteristics and its similarities with AOSD. To better understand the molecular pathways responsible of these similarities, we evaluated in the PBMCs of 4 active AOSD patients, 2 COVID19 patients with ARDS, and 2 HCs the expression of genes associated with iron metabolisms, with monocyte/macrophages activation, and finally with NETs formation.

Advances in Ferritin Physiology and Possible Implications in Bacterial Infection

Due to its advantageous redox properties, iron plays an important role in the metabolism of nearly all life. However, these properties are not only a boon but also the bane of such life forms. Since labile iron results in the generation of reactive oxygen species by Fenton chemistry, iron is stored in a relatively safe form inside of ferritin. Despite the fact that the iron storage protein ferritin has been extensively researched, many of its physiological functions are hitherto unresolved. However, research regarding ferritin's functions is gaining momentum. For example, recent major discoveries on its secretion and distribution mechanisms have been made as well as the paradigm-changing finding of intracellular compartmentalization of ferritin via interaction with nuclear receptor coactivator 4 (NCOA4). In this review, we discuss established knowledge as well as these new findings and the implications they may have for host-pathogen interaction during bacterial infection.

Ferritin-induced NETs lead to cytokine storm in AOSD

New research reveals that ferritin has an essential role in neutrophil extracellular trap (NET)-mediated inflammation, and suggests that NETs or the ferritin receptor MSR1 could be targeted for the treatment of adult-onset Still disease.