Biomarkers in Systemic Juvenile Idiopathic Arthritis, Macrophage Activation Syndrome and Their Importance in COVID Era

Advancing personalised precision treatment for Still's disease based on molecular characteristics and disease progression

Still's disease, a systemic autoinflammatory disorder with a classic multigenetic background, is characterised by polyarthritis, high-spiking fever, salmon-like evanescent skin rash, and hyperferritinaemia. Although the exact cause of Still's disease remains unclear, it is believed to be influenced by genetic factors, infections, and immune dysregulation. Current studies indicate that neutrophils and macrophages play crucial roles in the pathogenesis of Still's disease, along with involvement of natural killer cells, T cells, and B cells. Advances in biologic agents have expanded treatment strategies beyond conventional approaches, with cytokine-targeted agents showing promise in the management of Still's disease. Some cytokine-targeting biologic agents can be developed based on clinical manifestations, complications, immune cells, and molecular networks. Emphasis of immunophenotyping for precise clinical subtyping and targeted molecular therapies based on these findings is crucial for optimising treatment outcomes. In this Review, we discuss the latest advancements in the understanding of Still's disease pathogenesis and corresponding therapeutic approaches.

High Mobility Group Box Protein (HMGB1): A Potential Therapeutic Target for Diabetic Encephalopathy

HMGB (high mobility group B) is one of the ubiquitous non-histone nuclear protein superfamilies that make up the HMG (high mobility group) protein group. HMGB1 is involved in a variety of physiological and pathological processes in the human body, including a structural role in the cell nucleus as well as replication, repair, DNA transcription, and assembly of nuclear proteins. It functions as a signaling regulator in the cytoplasm and a pro-inflammatory cytokine in the extracellular environment. Among several studies, HMGB1 protein is also emerging as a crucial factor involved in the development and progression of diabetic encephalopathy (DE) along with other factors such as hyperglycaemia-induced oxidative and nitrosative stress. Diabetes' chronic side effect is DE, which manifests as cognitive and psychoneurological dysfunction. The HMGB1 is released outside to the extracellular medium in diabetes condition through active or passive routes, where it functions as a damage-associated molecular pattern (DAMP) molecule to activate several signaling pathways by interacting with receptors for advanced glycosylation end-products (RAGE)/toll like receptors (TLR). HMGB1 reportedly activates inflammatory pathways, disrupts the blood-brain barrier, causes glutamate toxicity and oxidative stress, and promotes neuroinflammation, contributing to the development of cognitive impairment and neuronal damage which is suggestive of the involvement of HMGB1 in the enhancement of the diabetes-induced encephalopathic condition. Additionally, HMGB1 is reported to induce insulin resistance, further exacerbating the metabolic dysfunction associated with diabetes mellitus (DM). Thus, the present review explores the possible pathways associated with DM-induced hyperactivation of HMGB1 ultimately leading to DE.

Proteomic Signatures of Multisystem Inflammatory Syndrome in Children (MIS-C) Associated with COVID-19: A Narrative Review

BACKGROUND/OBJECTIVES

Multisystem Inflammatory Syndrome in Children (MIS-C) is a post-infectious complication of COVID-19. MIS-C has overlapping features with other pediatric inflammatory disorders including Kawasaki Disease (KD), Macrophage Activation Syndrome (MAS), Toxic Shock Syndrome and sepsis. The exact mechanisms responsible for the clinical overlap between MIS-C and these conditions remain unclear, and biomarkers that could distinguish MIS-C from its clinical mimics are lacking. This study aimed to provide an overview of how proteomic methods, like Mass Spectrometry (MS) and affinity-based proteomics, can offer a detailed understanding of pathophysiology and aid in the diagnosis and prognosis of MIS-C.

METHODS

A narrative review of relevant studies published up to July 2024 was conducted.

RESULTS

We identified 15 studies and summarized their key proteomic findings. These studies investigated the serum or plasma proteome of MIS-C patients using MS, Proximity Extension, or Aptamer-based assays. The studies associated the proteomic profile of MIS-C with laboratory and clinical parameters and/or compared it with that of other diseases including acute COVID-19, KD, MAS, pediatric rheumatic diseases, sepsis and myocarditis or pericarditis following COVID-19 mRNA immunization. Depending on the method and the control group, different proteins were increased or decreased in the MIS-C group. The limitations and challenges in MIS-C proteomic research are also discussed, and future research recommendations are provided.

CONCLUSIONS

Although proteomics appear to be a promising approach for understanding the pathogenesis and uncovering candidate biomarkers in MIS-C, proteomic studies are still needed to recognize and validate biomarkers that could accurately discriminate MIS-C from its clinical mimics.

Longitudinal Fluctuations in Protein Concentrations and Higher-Order Structures in the Plasma Proteome of Kidney Failure Patients Subjected to a Kidney Transplant

Using proteomics and complexome profiling, we evaluated in a year-long study longitudinal variations in the plasma proteome of kidney failure patients, prior to and after a kidney transplantation. The post-transplant period was complicated by bacterial infections, resulting in dramatic changes in the proteome, attributed to an acute phase response (APR). As positive acute phase proteins (APPs), being elevated upon inflammation, we observed the well-described C-reactive protein and Serum Amyloid A (SAA), but also Fibrinogen, Haptoglobin, Leucine-rich alpha-2-glycoprotein, Lipopolysaccharide-binding protein, Alpha-1-antitrypsin, Alpha-1-antichymotrypsin, S100, and CD14. As negative APPs, being downregulated upon inflammation, we identified the well-documented Serotransferrin and Transthyretin, but added Kallistatin, Heparin cofactor 2, and interalpha-trypsin inhibitor heavy chain H1 and H2 (ITIH1, ITIH2). For the patient with the most severe APR, we performed plasma complexome profiling by SEC-LC-MS on all longitudinal samples. We observed that several plasma proteins displaying alike concentration patterns coelute and form macromolecular complexes. By complexome profiling, we expose how SAA1 and SAA2 become incorporated into high-density lipid particles, replacing largely Apolipoprotein (APO)A1 and APOA4. Overall, our data highlight that the combination of in-depth longitudinal plasma proteome and complexome profiling can shed further light on correlated variations in the abundance of several plasma proteins upon inflammatory events.

Cytokine Storm Syndrome Associated with Systemic Juvenile Idiopathic Arthritis

The cytokine storm syndrome (CSS) associated with systemic juvenile idiopathic arthritis (sJIA) has widely been referred to as macrophage activation syndrome (MAS). In this chapter, we use the term sJIA-associated CSS (sJIA-CSS) when referring to this syndrome and use the term MAS when referencing publications that specifically report on sJIA-associated MAS.

Clinical and laboratory features associated with macrophage activation syndrome in Still's disease: data from the international AIDA Network Still's Disease Registry

To characterize clinical and laboratory signs of patients with Still's disease experiencing macrophage activation syndrome (MAS) and identify factors associated with MAS development. Patients with Still's disease classified according to internationally accepted criteria were enrolled in the AutoInflammatory Disease Alliance (AIDA) Still's Disease Registry. Clinical and laboratory features observed during the inflammatory attack complicated by MAS were included in univariate and multivariate logistic regression analysis to identify factors associated to MAS development. A total of 414 patients with Still's disease were included; 39 (9.4%) of them developed MAS during clinical history. At univariate analyses, the following variables were significantly associated with MAS: classification of arthritis based on the number of joints involved (p = 0.003), liver involvement (p = 0.04), hepatomegaly (p = 0.02), hepatic failure (p = 0.01), axillary lymphadenopathy (p = 0.04), pneumonia (p = 0.03), acute respiratory distress syndrome (p < 0.001), platelet abnormalities (p < 0.001), high serum ferritin levels (p = 0.009), abnormal liver function tests (p = 0.009), hypoalbuminemia (p = 0.002), increased LDH (p = 0.001), and LDH serum levels (p < 0.001). At multivariate analysis, hepatomegaly (OR 8.7, 95% CI 1.9-52.6, p = 0.007) and monoarthritis (OR 15.8, 95% CI 2.9-97.1, p = 0.001), were directly associated with MAS, while the decade of life at Still's disease onset (OR 0.6, 95% CI 0.4-0.9, p = 0.045), a normal platelet count (OR 0.1, 95% CI 0.01-0.8, p = 0.034) or thrombocytosis (OR 0.01, 95% CI 0.0-0.2, p = 0.008) resulted to be protective. Clinical and laboratory factors associated with MAS development have been identified in a large cohort of patients based on real-life data.

Disentangling the common genetic architecture and causality of rheumatoid arthritis and systemic lupus erythematosus with COVID-19 outcomes: Genome-wide cross trait analysis and bidirectional Mendelian randomization study

Coronavirus Disease (COVID-19) may cause a dysregulation of the immune system and has complex relationships with multiple autoimmune diseases, including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). However, little is known about their common genetic architecture. Using the latest data from COVID-19 host genetics consortium and consortia on RA and SLE, we conducted a genome-wide cross-trait analysis to examine the shared genetic etiology between COVID-19 and RA/SLE and evaluated their causal associations using bidirectional Mendelian randomization (MR). The cross-trait meta-analysis identified 23, 28, and 10 shared genetic loci for severe COVID-19, COVID-19 hospitalization, and SARS-CoV-2 infection with RA, and 14, 17, and 7 shared loci with SLE, respectively. Co-localization analysis identified five causal variants in TYK2, IKZF3, PSORS1C1, and COG6 for COVID-19 with RA, and four in CRHR1, FUT2, and NXPE3 for COVID-19 with SLE, involved in immune function, angiogenesis and coagulation. Bidirectional MR analysis suggested RA is associated with a higher risk of COVID-19 hospitalization, and COVID-19 is not related to RA or SLE. Our novel findings improved the understanding of the genetic etiology shared by COVID-19, RA and SLE, and suggested an increased risk of COVID-19 hospitalization in people with higher genetic liability to RA.