Serum proteome analysis of systemic JIA and related pulmonary alveolar proteinosis identifies distinct inflammatory programs and biomarkers

Abstract

ObjectivesRecent observations in systemic Juvenile Idiopathic Arthritis (sJIA) suggest an increasing incidence of high-mortality interstitial lung disease (ILD), characterized pathologically by a variant of pulmonary alveolar proteinosis (PAP). The co-occurrence of macrophage activation syndrome (MAS) and PAP in sJIA suggested a shared pathology, but features of drug reaction such as anaphylaxis, rashes, and eosinophilia are also common in these patients. We sought to investigate immunopathology and identify biomarkers of this lung disease.MethodsWe used SOMAscan to measure >1300 analytes in serum samples from healthy controls and patients with sJIA-PAP, sJIA, sJIA-MAS, and other associated diseases, and verified selected findings by ELISA and lung immunostaining. Because a sample’s proteome may reflect multiple states (SJIA, MAS, SJIA-PAP), we used linear regression modeling to identify subsets of altered proteins associated with each state.ResultsMarkers identified for sJIA, including SAA, S100A9, and S100A12, were consistent with previous reports. Proteome alterations in sJIA and MAS overlapped substantially, including new findings of heat shock proteins and glycolytic enzymes. sJIA, MAS, and sJIA-PAP shared elevation of IL-18. Importantly, we identified a unique sJIA-PAP signature whose expression was independent of sJIA-MAS activity. Key proteins were ICAM5 and MMP7, previously observed markers of fibrotic ILD. Immunohistochemistry showed expression of these proteins in sJIA-PAP lung, supporting a pulmonary source. The eosinophil chemoattractant CCL11 was elevated in sJIA-PAP, but not sJIA/MAS or other PAP.ConclusionsWe found novel circulating proteins associated specifically with sJIA, sJIA/MAS and sJIA-PAP. Select biomarkers, such as ICAM5, could aid in early detection and management of sJIA-PAP.Key MessagesPulmonary Alveolar Proteinosis (PAP) occurring in the setting of Systemic Juvenile Idiopathic Arthritis (sJIA) is an increasingly-noted, dangerous condition that has been associated with Macrophage Activation Syndrome (MAS).We evaluated >1300 serum proteins by aptamer array, verifying and localizing key proteins, and identified novel pathways associated with MAS (HSPs, glycolysis), candidate pathways/proteins associated with PAP in sJIA (e.g., ICAM5, MMP7, and type 2 chemokines), and divergence of the sJIA/MAS and sJIA-PAP proteomes.This analysis supports the evaluation of novel pathways in MAS, the validation of screening/monitoring biomarkers in sJIA-PAP, and the management of PAP as a disease process enmeshed with, but distinct from, sJIA and MAS.

In-Depth Serum Proteomics by DIA-MS with In Silico Spectral Libraries Reveals Dynamics during the Active Phase of Systemic Juvenile Idiopathic Arthritis

“…In recent sJIA serum proteomics studies using SOMAscan, a total of 1317 protein sets were used for the analysis. 12 In comparison to the total proteins obtained in our analysis, 570 proteins overlapped, but many unique proteins were also obtained in each of the analyses ( Figure S2A ). Focusing on the proteins that changed during the active phase of sJIA, 55 proteins were found in common, despite differences in the comorbidities and race of the patients studied ( Figure S2B and Table S3 ).…”

“…Recently, it was reported that the analysis of sJIA patient serum using SOMAscan identified a new candidate biomarker and variable protein groups in sJIA that were associated with pulmonary alveolar proteinosis (PAP). 12 Thus, detailed studies of changes in serum protein levels using proteome analysis techniques may reveal important factors related to the disease and proteins that can serve as new biomarkers, which may provide clues to understanding the pathogenesis of the disease. In this study, we performed a proteomic analysis of sJIA serum by overlapping window DIA-MS to evaluate the performance of the analytical approach and reveal changes in proteome profiling according to disease activity.…”

“…In an MS-based proteome analysis, the number of detectable proteins is limited by the effect of high-abundance proteins such as albumin and γ-globulin. , To reduce the dynamic range of these protein concentrations, high-abundance protein depletion methods using antibody columns are actively used. However, a conventional data-dependent acquisition mass spectrometry (DDA-MS) based single-shot proteome analysis does not provide sufficient proteome coverage, even for depleted serum. ,, Because of this difficulty, a SOMAscan assay using aptamers and a multiplex assay using an antibody-based proximity extension assay have recently attracted attention as methods for identifying more than 1000 proteins from serum without using MS. − However, MS-based proteome analysis techniques have also undergone great technological innovation. The advent of data-independent acquisition mass spectrometry (DIA-MS) has dramatically expanded the proteome coverage of a single-shot proteome analysis .…”

“…It is also known that the driving cytokines, including TNFα and IFNγ, are altered during MAS in sJIA patients. , However, the pathogenesis leading to systemic inflammation and the mechanisms underlying the prolonged inflammation remain unclear. Recently, it was reported that the analysis of sJIA patient serum using SOMAscan identified a new candidate biomarker and variable protein groups in sJIA that were associated with pulmonary alveolar proteinosis (PAP) . Thus, detailed studies of changes in serum protein levels using proteome analysis techniques may reveal important factors related to the disease and proteins that can serve as new biomarkers, which may provide clues to understanding the pathogenesis of the disease.…”

Rare, rarer, lung involvement in adult-onset Still's disease: A mini-review

“…Using serum proteome analyses of 162 patients, Chen et al recently underlined the importance of IL-18 as it was stronger upregulated in sJIA patients with LD as compared to those without. Also, they identified ICAM5, a cell adhesion molecule, as a potential biomarker that is specifically upregulated in sJIA-LD (and not in general sJIA or MAS) and might be able to detect patients at risk at an early timepoint (43). However, this finding has not been replicated for AOSD-LD so far.…”