Elevated serum gasdermin D N-terminal implicates monocyte and macrophage pyroptosis in adult-onset Still's disease

Targeting enhanced cell death represents a potential therapeutic strategy for VEXAS syndrome

Objectives

To unravel the mechanisms underlying cell death in the vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome using peripheral blood samples and to assess the clinical value of this knowledge.

Methods

Nine patients undergoing treatment for VEXAS syndrome at Yokohama City University Hospital were included in this study. Monocytes and neutrophils were isolated from peripheral blood and then monocytes were differentiated into polarized macrophages. Viable cell counts, cell death assays and measurements of various indicators such as high mobility group box 1 (HMGB1) concentration, extracellular adenosine triphosphate (ATP) concentration, annexin V level and caspase 1, 3 and 7 activities were performed.

Results

Elevated cell death of monocytes and neutrophils was observed in VEXAS syndrome patients, as indicated by cultured cell counts and cell death assays. Annexin V assays and measurements of caspase 1, 3 and 7 activities suggested increased apoptosis and pyroptosis in these cells. Serum HMGB1 levels were significantly elevated in VEXAS syndrome patients and decreased after prednisolone (PSL) dose escalation. Monocytes and neutrophils from the VEXAS group exhibited heightened extracellular ATP secretion, which was significantly reduced by soluble PSL co-culture.

Conclusion

This study confirms increased cell death of monocytes and neutrophils and damage-associated molecular patterns in VEXAS syndrome, and these findings may be valuable for drug screening, therapeutic strategies and as biomarkers.

New discoveries in the genetics and genomics of systemic juvenile idiopathic arthritis

INTRODUCTION

Systemic juvenile idiopathic arthritis (sJIA) is a severe inflammatory condition with onset in childhood. It is sporadic, but elements of its stereotypical innate immune responses are likely genetically encoded by both common variants with small effect sizes and rare variants with larger effects.

AREAS COVERED

Genomic investigations have defined the unique genetic architecture of sJIA. Identification of the class II HLA locus as the strongest sJIA risk factor for the first time brought attention to T lymphocytes and adaptive immune mechanisms in sJIA. The importance of the human leukocyte antigen (HLA) locus was reinforced by recognition that HLA-DRB1*15 alleles are strongly associated with development of drug reactions and sJIA-associated lung disease (sJIA-LD). At the IL1RN locus, genetic variation relates to both risk of sJIA and may also predict non-response to anakinra. Finally, rare genetic variants may have critical roles in disease complications, such as homozygous LACC1 mutations in families with an sJIA-like illness, and hemophagocytic lymphohistiocytosis (HLH) gene variants in some children with macrophage activation syndrome (MAS).

EXPERT OPINION

Genetic and genomic analysis of sJIA holds great promise for both basic discovery of the course and complications of sJIA, and may help guide personalized medicine and therapeutic decision-making.

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.

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.

Pyroptosis: the potential eye of the storm in adult-onset Still's disease

Pyroptosis, a form of programmed cell death with a high pro-inflammatory effect, causes cell lysis and leads to the secretion of countless interleukin-1β (IL-1β) and IL-18 cytokines, resulting in a subsequent extreme inflammatory response through the caspase-1-dependent pathway or caspase-1-independent pathway. Adult-onset Still's disease (AOSD) is a systemic inflammatory disease with extensive disease manifestations and severe complications such as macrophage activation syndrome, which is characterized by high-grade inflammation and cytokine storms regulated by IL-1β and IL-18. To date, the pathogenesis of AOSD is unclear, and the available therapy is unsatisfactory. As such, AOSD is still a challenging disease. In addition, the high inflammatory states and the increased expression of multiple pyroptosis markers in AOSD indicate that pyroptosis plays an important role in the pathogenesis of AOSD. Accordingly, this review summarizes the molecular mechanisms of pyroptosis and describes the potential role of pyroptosis in AOSD, the therapeutic practicalities of pyroptosis target drugs in AOSD, and the therapeutic blueprint of other pyroptosis target drugs.

The gasdermins: a pore-forming protein family expressed in the epidermis

Gasdermins comprise a family of pore-forming proteins, which play critical roles in (auto)inflammatory diseases and cancer. They are expressed as self-inhibited precursor proteins consisting of an aminoterminal cytotoxic effector domain (NT-GSDM) and a carboxyterminal inhibitor domain (GSDM-CT) separated by an unstructured linker region. Proteolytic processing in the linker region liberates NT-GSDM, which translocates to membranes, forms oligomers, and induces membrane permeabilization, which can disturb the cellular equilibrium that can lead to cell death. Gasdermin activation and pore formation are associated with inflammation, particularly when induced by the inflammatory protease caspase-1 upon inflammasome activation. These gasdermin pores allow the release of the pro-inflammatory cytokines interleukin(IL)-1β and IL-18 and induce a lytic type of cell death, termed pyroptosis that supports inflammation, immunity, and tissue repair. However, even at the cellular level, the consequences of gasdermin activation are diverse and range from induction of programmed cell death - pyroptosis or apoptosis - to poorly characterized protective mechanisms. The specific effects of gasdermin activation can vary between species, cell types, the membrane that is being permeabilized (plasma membrane, mitochondrial membrane, etc.), and the overall biological state of the local tissue/cells. In epithelia, gasdermins seem to play crucial roles. Keratinocytes represent the main cell type of the epidermis, which is the outermost skin layer with an essential barrier function. Compared to other tissues, keratinocytes express all members of the gasdermin family, in part in a differentiation-specific manner. That raises questions regarding the specific roles of individual GSDM family members in the skin, the mechanisms and consequences of their activation, and the potential crosstalk between them. In this review, we summarize the current knowledge about gasdermins with a focus on keratinocytes and the skin and discuss the possible roles of the different family members in immunity and disease.

Association between CCR2 and CCL2 expression and NET stimulation in adult-onset Still's disease

Adult-onset Still's disease (AOSD) is a systemic inflammatory disease characterized by the activation of monocyte-derived cells and the release of neutrophil extracellular traps (NET). C-C motif ligand (CCL) 2 is a chemoattractant that interacts with the C-C motif chemokine receptor (CCR) 2, resulting in monocyte recruitment and activation. CCL2 and CCR2 were measured with enzyme-linked immunosorbent assay (ELISA) at the serum level, and using immunohistochemical staining at the skin and lymph node tissues levels. THP-1 cell lysates were analyzed using western blot and ELISA after NET stimulation in patients with AOSD. Serum CCL2 level was higher in patients with AOSD than in patients with rheumatoid arthritis and healthy controls (HCs). In patients with AOSD, the percentage of CCL2-positive inflammatory cells in the skin tissues and CCR2-positive inflammatory cells in the lymph nodes increased, compared to that in HCs and in patients with reactive lymphadenopathy, respectively. NET induced in patients with AOSD enhanced the secretion of CCR2, higher CCR2 expression in monocytes, and the levels of interleukin (IL)-1β, IL-6, and IL-18 from THP-1 cells. Our findings suggest that upregulation of the CCL2-CCR2 axis may contribute to the clinical and inflammatory characteristics of AOSD.

Cytokine profile, ferritin and multi-visceral involvement characterize macrophage activation syndrome during adult-onset Still's disease

OBJECTIVES

To multidimensionally characterize macrophage activation syndrome (MAS) complicating adult-onset Still's disease (AOSD) considering cytokine profile, inflammatory markers and multi-visceral involvement of the disease. To perform a high-dimensional phenotypic analysis of circulating immune cells in AOSD patients with and without MAS. To assess interferon (IFN)-related pathways in AOSD synovial tissues by a bulky RNA sequencing.

METHODS

Clinical and biologic data were collected and compared in AOSD patients with and without MAS. Sera biomolecules were analysed by Luminex multiplexing technology. Mass cytometry (CyTOF) was used to characterize circulating immune cells. A bulky RNA sequencing was performed in AOSD synovial tissues.

RESULTS

Forty consecutive AOSD patients were assessed, 14 complicated with MAS. Paralleling with increases of systemic score and ferritin, MAS patients showed higher levels of IL-1α, IL-1β, IL-1Ra, IL-2Ra, IL-6, IL-10, IL-17A, IFN-γ, G-CSF, MCP-1, MIP-1α and SCF. Combining the discriminatory ability of these data in identifying MAS, the best model was composed by systemic score, ferritin, IFN-γ and IL-10. By CyTOF analysis, MAS patients showed an increase of circulating 'classical monocytes' and a reduction of total NK cells. Our assessment showed 3477 IFN-related genes (IRGs) were differently expressed in AOSD synovial tissues.

CONCLUSIONS

A multidimensional characterization of AOSD patients suggested that IFN-γ, IL-10, ferritin and systemic score discriminated the occurrence of cytokine storm syndrome associated with MAS. The inflammatory milieu of AOSD and MAS may be related to a signature of circulating immune cells. Finally, our results about IRGs reinforced the role of IFN-γ in these patients.

Serum gasdermin D levels are associated with the chest computed tomography findings and severity of COVID-19

BACKGROUND

The role of programmed cell death, especially pyroptosis and apoptosis, in unfavorable immune responses in COVID-19 remains to be elucidated.

METHODS

We conducted a cross-sectional analysis to investigate the association between the serum gasdermin D (GSDMD) levels, a pyroptotic marker, and caspase-cleaved cytokeratin 18 fragment (M30), an apoptotic marker, and the clinical status and abnormal chest computed tomography (CT) findings in patients with COVID-19.

RESULTS

In this study, 46 patients diagnosed with COVID-19 were divided into the following three groups according to the disease severity: mild to moderate group (n = 10), severe group (n = 14), and critical group (n = 22). The serum GSDMD levels were higher in the critical group than in the mild to moderate group (P = 0.016). In contrast, serum M30 levels were lower in the critical group than in the severe group (P = 0.048). Patients who required mechanical ventilation or died had higher serum GSDMD levels than those who did not (P = 0.007). Area of consolidation only and of ground glass opacity plus consolidation positively correlated with serum GSDMD levels (r = 0.56, P < 0.001 and r = 0.53, P < 0.001, respectively).

CONCLUSION

Higher serum GSDMD levels are associated with critical respiratory status and the consolidation area on chest CT in patients with COVID-19, suggesting that excessive activation of pyroptosis may affect the clinical manifestations in patients with COVID-19.

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.

The Roles of Monocytes and Macrophages in Behçet’s Disease With Focus on M1 and M2 Polarization

Behçet’s disease (BD) is a systemic inflammatory disease characterized by recurrent oral ulcers, genital ulcers, cutaneous inflammation, and uveitis. In addition, other potentially life-threatening lesions may occur in the intestinal tract, blood vessels, and central nervous system. This heterogeneity of the BD phenotype hampers development of a targeted treatment strategy. The pathogenesis of BD is not fully elucidated, but it is likely that genetically susceptible people develop BD in response to environmental factors, such as microbiome factors. Genetic analyses have identified various BD susceptibility loci that function in HLA-antigen presentation pathways, Th1 and Th17 cells, and autoinflammation related to monocytes/macrophages, or that increase levels of pro-inflammatory cytokines, reduce levels of anti-inflammatory cytokines, or act in dysfunctional mucous barriers. Our functional analyses have revealed that impairment of M2 monocyte/macrophage-mediated anti-inflammatory function through IL-10 is crucial to BD pathogenesis. We, therefore, propose that BD is an M1-dominant disease. In this review, we describe the roles of monocytes and macrophages in BD and consider the potential of these cells as therapeutic targets.

Association of serum Gasdermin D with anti-N-methyl-D-aspartate receptor encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disease of the central nervous system. Gasdermin D (GSDMD) is associated with autoimmune disorders and neuroinflammatory disorders, but its role in anti-NMDAR encephalitis is unclear. In this study, we measured serum levels of GSDMD in 42 patients with anti-NMDAR encephalitis and 25 healthy controls. Of the 42 patients, 17 had follow-up evaluation of GSDMD levels and modified Rankin scale (mRS) scores at 3 months. Association of GSDMD with anti-NMDAR encephalitis and its clinical parameters were evaluated. Serum GSDMD levels were significantly higher in patients with anti-NMDAR encephalitis than in healthy controls (p = 0.002, p_adjusted  = 0.009), especially in males (p = 0.001, p_adjusted  = 0.022). This was also evident in patients with severe impairment (mRS >3 vs mRS ≤3; p < 0.001). Serum GSDMD was associated with mRS before and after adjustment for age and gender (r = 0.440 and 0.430, p = 0.004 and 0.006, respectively) as well as serum CH50 (r = -0.419 and -0.426, p = 0.011 and 0.012, respectively). Furthermore, 3-month follow-up evaluation revealed that after treatment, anti-NMDAR encephalitis patients had significantly decreased serum GSDMD levels (p = 0.007) and significantly decreased mRS scores (p = 0.002) compared with before treatment. Furthermore, the changes in mRS scores were negatively associated with changes in GSDMD levels, although the associations were not significant (r = -0.222, p = 0.393). Our findings show that serum GSDMD levels are elevated in anti-NMDAR encephalitis and are associated with disease prognosis.

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.