Alveolar macrophage gene expression in a mouse model of MAS
Ontology highlight
ABSTRACT: Macrophage activation syndrome (MAS) is a life-threatening complication of systemic juvenile idiopathic arthritis (SJIA), and increasingly reported in association with severe lung disease (SJIA-LD) of unknown etiology. This study mechanistically defines the novel observation of pulmonary inflammation in the TLR9 mouse model of MAS that recapitulate key features of SJIA-LD, including IFNg activation. In acute MAS, lungs exhibit a mild but diffuse lymphocyte-predominant perivascular, interstitial inflammation with elevated IFNg, IFN-induced chemokines, and alveolar macrophage (AMf) expression of IFNg-induced genes. However, MAS resolution demonstrated AMf expansion and increased interstitial inflammation. AMf microarrays confirmed IFNg-induced proinflammatory polarization during acute MAS, which switches towards anti-inflammatory phenotype during MAS resolution. Interestingly, recurrent MAS increased alveolar inflammation, and reset polarization towards a pro-inflammatory state. Furthermore, in mice bearing macrophages insensitive to IFNg, both systemic feature of MAS and pulmonary inflammation were markedly attenuated. These findings demonstrate experimental MAS induces IFNg-driven pulmonary inflammation, and define this system for further study of and treatment validation in SJIA-LD. We used microarrays to study whole transcriptome analysis of alveolar macrophages in the TLR9 mouse model of MAS during both acute MAS and MAS resolution.
Project description:Macrophage activation syndrome (MAS) is a life-threatening cytokine storm syndrome complicating systemic juvenile idiopathic arthritis (SJIA) and driven by IFN-gamma. SJIA and MAS are also associated with an unexplained emerging inflammatory lung disease (SJIA-LD), with our recent work supporting pulmonary activation of IFN-gamma pathways as a pathologic link between SJIA-LD and MAS. Our objective was to mechanistically define the novel observation of pulmonary inflammation in the TLR9 mouse model of MAS. In acute MAS, lungs exhibit mild but diffuse CD4-predominant, perivascular interstitial inflammation with elevated IFN-gamma, IFN-induced chemokines, and alveolar macrophage expression of IFN-gamma-induced genes. Single-cell RNA-sequencing confirmed IFN-driven transcriptional changes across immune and parenchymal lung cell types. Resolution of MAS was associated with increased alveolar macrophage and interstitial lymphocytic infiltration. alveolar macrophage microarrays confirmed IFN-gamma-induced proinflammatory polarization during acute MAS, which switches towards an anti-inflammatory phenotype during MAS resolution. Interestingly, recurrent MAS led to increased alveolar inflammation and lung injury, and reset alveolar macrophagepolarization towards a proinflammatory state. Furthermore, in mice bearing macrophages insensitive to IFN-gamma, both systemic feature of MAS and pulmonary inflammation were attenuated. These findings demonstrate that experimental MAS induces IFN-gamma-driven pulmonary inflammation replicating key features of SJIA-LD, and provides a model system for testing novel treatments directed towards SJIA-LD.
Project description:Systemic juvenile idiopathic arthritis (SJIA) is a clinically heterogenous systemic inflammatory disorder sometimes complicated by macrophage activation syndrome (MAS) and lung disease (LD), which are thought to be driven by IFN signaling. To identify cellular sources and novel gene programs underlying SJIA pathogenesis, we performed the first in-depth single-cell RNA Sequencing (scRNA-Seq) analysis of 21 SJIA, SJIA-LD, and SJIA-MAS patient PBMCs. To define novel heterogenous patient-subtypes associated with shared transcriptional responses and associate these with clinical and diagnostic metadata, we developed the tools UDON and SATAY-UDON. These tools identify hidden patient-subtypes, including a novel Complement and IFN signaling gene program expressed by SJIA-LD monocyte populations, unravel cellular sources of IFN signaling in SJIA-MAS as CD4 T cells and monocytic cell types, and identify a previously unknown role for platelets and S100 proteins as drivers of systemic inflammation. These data provide insights into new potential therapeutic targets for SJIA complications.
Project description:We used SOMAscan to measure >1300 analytes in sera from healthy controls and patients with sJIA, MAS, sJIA-LD and other related diseases.
Project description:Systemic Juvenile Idiopathic Arthritis (sJIA) has been strongly associated with macrophage activation syndrome (MAS). To better understand the pathogenesid of sJIA and to facilitate the search for MAS biomarkers, we examine gene expression profiles in untreated new onset sJIA. 17 new onset sJIA patients were included in the study. 5 of the 17 patients showed evidence of subclinical MAS and 2 eventually developed overt MAS. Keywords: disease versus control
Project description:Systemic Juvenile Idiopathic Arthritis (sJIA) has been strongly associated with macrophage activation syndrome (MAS). To better understand the pathogenesid of sJIA and to facilitate the search for MAS biomarkers, we examine gene expression profiles in untreated new onset sJIA. 17 new onset sJIA patients were included in the study. 5 of the 17 patients showed evidence of subclinical MAS and 2 eventually developed overt MAS. Keywords: disease versus control Peripheral blood mononuclear cells (PBMCs) were separated using a Ficoll gradient from the 17 new onset sJIA patients and 30 normal control. RNA was extracted from the PBMCS and subsequently hybridized to Affymetrix microarrays
Project description:Objective. Follistatin-like protein 1 (FSTL-1) is a secreted glycoprotein that is over-expressed in certain inflammatory diseases. Our objective in this study was to correlate FSTL-1 levels with measures of clinical disease activity in systemic juvenile idiopathic arthritis (sJIA), including macrophage activation syndrome (MAS). Methods. FSTL-1 serum levels were measured by ELISA in 28 patients with sJIA, including 7 patients who developed MAS, as well as in 30 normal controls. Levels were correlated with erythrocyte sedimentation rate (ESR), ferritin and sIL-2Rα expression. Differential gene expression based on FSTL-1 levels was analyzed in peripheral blood mononuclear cells (PBMCs). Results. FSTL-1 serum levels were elevated at time of presentation (pre-treatment) of sJIA (mean 200.7 ng/ml) and decreased to normal (mean 133.7 ng/ml) over 24 months (p<0.01). FSTL-1 levels were markedly elevated during acute MAS (mean 279.8 ng/ml) and decreased to normal (mean 120.3 ng/ml) following treatment (p<0.001). FSTL-1 levels correlated with serum markers of inflammation, including sIL-2Rα and ferritin, in patients with MAS. PBMCs from patients with FSTL-1 levels >200 ng/ml showed an increase in expression of genes related to innate immunity and erythropoiesis, and decrease in NK cell function. Patients with the highest FSTL-1 levels at disease onset (>300 ng/ml) ultimately required cyclosporine treatment. Conclusion. In patients with sJIA, serum FSTL-1 is a biomarker for MAS and FSTL-1 levels at presentation may predict subsequent disease course. Patients with FSTL-1 levels >200 ng/ml had altered gene expression patterns suggestive of subclinical MAS and may represent a subgroup of sJIA with more severe disease. FSTL-1 serum levels were measured by ELISA in 28 patients with sJIA, including 7 patients who developed MAS, as well as in 30 normal controls. Levels were correlated with erythrocyte sedimentation rate (ESR), ferritin and sIL-2Rα expression. Differential gene expression based on FSTL-1 levels was analyzed in peripheral blood mononuclear cells (PBMCs). Only 11 patients were run on microarray.
Project description:Objective. Follistatin-like protein 1 (FSTL-1) is a secreted glycoprotein that is over-expressed in certain inflammatory diseases. Our objective in this study was to correlate FSTL-1 levels with measures of clinical disease activity in systemic juvenile idiopathic arthritis (sJIA), including macrophage activation syndrome (MAS). Methods. FSTL-1 serum levels were measured by ELISA in 28 patients with sJIA, including 7 patients who developed MAS, as well as in 30 normal controls. Levels were correlated with erythrocyte sedimentation rate (ESR), ferritin and sIL-2Rα expression. Differential gene expression based on FSTL-1 levels was analyzed in peripheral blood mononuclear cells (PBMCs). Results. FSTL-1 serum levels were elevated at time of presentation (pre-treatment) of sJIA (mean 200.7 ng/ml) and decreased to normal (mean 133.7 ng/ml) over 24 months (p<0.01). FSTL-1 levels were markedly elevated during acute MAS (mean 279.8 ng/ml) and decreased to normal (mean 120.3 ng/ml) following treatment (p<0.001). FSTL-1 levels correlated with serum markers of inflammation, including sIL-2Rα and ferritin, in patients with MAS. PBMCs from patients with FSTL-1 levels >200 ng/ml showed an increase in expression of genes related to innate immunity and erythropoiesis, and decrease in NK cell function. Patients with the highest FSTL-1 levels at disease onset (>300 ng/ml) ultimately required cyclosporine treatment. Conclusion. In patients with sJIA, serum FSTL-1 is a biomarker for MAS and FSTL-1 levels at presentation may predict subsequent disease course. Patients with FSTL-1 levels >200 ng/ml had altered gene expression patterns suggestive of subclinical MAS and may represent a subgroup of sJIA with more severe disease.
Project description:Systemic juvenile idiopathic arthritis (SJIA) confers high risk for macrophage activation syndrome (MAS), a life-threatening episode of hyperinflammation driven by IFN-γ. Monocytes in SJIA display IFNγ-hyperresponsiveness, but the molecular basis of this remains unclear. The objective of this study is to identify circulating monocyte polarization phenotypes including features of interferon response. Bulk RNA-seq of purified monocytes was performed on healthy controls as well as patients with inactive SJIA (satisfy Wallace criteria for clinically inactive disease), active SJIA, new-onset SJIA (NOS), and macrophage activation syndrome (2016 MAS Classification Criteria). We observed marked transcriptional changes in patients with elevated ferritin levels. We also identified substantial overlap with multiple polarization states but little evidence of IFN-induced signature.
Project description:Systemic juvenile idiopathic arthritis (SJIA) confers high risk for macrophage activation syndrome (MAS), a life-threatening episode of hyperinflammation driven by IFN-γ. Monocytes in SJIA display IFN-γhyperresponsiveness, but the molecular basis of this remains unclear. The objective of this study is to identify monocyte and macrophage polarization phenotypes including features of interferon response. Bulk RNA-seq of purified SJIA monocytes revealed marked transcriptional changes in patients with elevated ferritin levels. We identified substantial overlap with multiple polarization states but little evidence of IFN-induced signature. Interestingly, among the most highly upregulated genes was tripartite motif containing 8 (TRIM8), a positive regulator of IFN-γ signaling. Single cell RNA-seq of bone marrow macrophages (BMM) from a patient with SJIA and early MAS identified a distinct subpopulation of BMM with altered transcriptomes consistent with hemophagocytes, including upregulated IFN-γ response pathways. These BMM also showed significantly increased expression of TRIM8. In vitro knock-down of TRIM8 in macrophages caused significant reductions in IFN-γ responsiveness. In conclusions, we identify a clear IFN-γ response phenotype in BMM during MAS. TRIM8 is upregulated in both monocytes and macrophages in SJIA, and required for macrophage IFN-γ response in vitro, providing a molecular mechanism and novel therapeutic for monocyte hyperresponsiveness to IFN-.
Project description:Macrophages play a crucial role in eliminating respiratory pathogens. Both pulmonary resident alveolar macrophages (AMs) and recruited macrophages contribute to detecting, responding to, and resolving infections in the lungs. Despite their distinct functions, it remains unclear how these macrophage subsets regulate their responses to infection, including how activation by the cytokine IFNg is regulated. This shortcoming prevents the development of therapeutics that effectively target distinct lung macrophage populations without exacerbating inflammation. We aimed to better understand the transcriptional regulation of resting and IFNg-activated cells using a new ex vivo model of AMs from mice, fetal liver-derived alveolar-like macrophages (FLAMs), and immortalized bone marrow-derived macrophages (iBMDMs). Our findings reveal that IFNg robustly activates both macrophage types; however, the profile of activated IFNg-stimulated genes varies greatly between these cell types. Notably, FLAMs show limited expression of costimulatory markers essential for T cell activation upon stimulation with only IFNg. To understand cell type-specific differences, we examined how the inhibition of the regulatory kinases GSK3a/b alters the IFNg response. GSK3a/b controlled distinct IFNg responses, and in AM-like cells, we found GSK3a/b restrained the induction of type I IFN and TNF, thus preventing the robust expression of costimulatory molecules and limiting CD4+ T cell activation. Together, these data suggest that the capacity of AMs to respond to IFNg is restricted in a GSK3a/b-dependent manner and that IFNg responses differ across distinct macrophage populations. These findings lay the groundwork to identify new therapeutic targets that activate protective pulmonary responses during infection without driving deleterious inflammation.