High acute phase protein levels correlate with pulmonary and skin involvement in patients with diffuse systemic sclerosis

Personalized Medicine for Systemic Sclerosis-Associated Interstitial Lung Disease

Purpose of the review

Systemic sclerosis (SSc) is a rare immune-mediated connective tissue disease with high morbidity and mortality. Interstitial lung disease (ILD) is now the leading cause of death for patients with SSc. While several therapeutic agents have been approved for SSc-ILD, opportunities remain for a personalized medicine approach to improve patient outcomes. The purpose of this narrative review is to summarize the current state of personalized medicine for SSc-ILD and future directions to facilitate earlier diagnosis, disease stratification, prognostication, and determination of treatment response. We also review opportunities for personalized medicine approaches within clinical trial design for SSc-ILD.

Recent findings

The management of SSc-ILD remains challenging due to its variable clinical course and current deficits in predicting which individuals will develop progressive pulmonary fibrosis. There have additionally been many challenges in clinical trial design due to limitations in enrichment strategies. Emerging data suggest that serum, radiologic, and other novel biomarkers could be utilized to assess disease activity and treatment response on an individual level.

Summary

Personalized medicine is emerging as a way to address unmet challenges in SSc-ILD and has applicability for identifying stratifying, prognostic, and therapeutic markers for routine clinical care and clinical trial design.

The potential role of serum amyloid A as biomarker of rheumatic diseases: a systematic review and meta-analysis

The identification of novel, robust biomarkers for the diagnosis of rheumatic diseases (RDs) and the presence of active disease might facilitate early treatment and the achievement of favourable long-term outcomes. We conducted a systematic review and meta-analysis of studies investigating the acute phase reactant, serum amyloid A (SAA), in RD patients and healthy controls to appraise its potential as diagnostic biomarker. We searched PubMed, Scopus, and Web of Science from inception to 10 April 2024 for relevant studies. We evaluated the risk of bias and the certainty of evidence using the JBI Critical Appraisal Checklist and GRADE, respectively (PROSPERO registration number: CRD42024537418). In 32 studies selected for analysis, SAA concentrations were significantly higher in RD patients compared to controls (SMD = 1.61, 95% CI 1.24-1.98, p < 0.001) and in RD patients with active disease compared to those in remission (SMD = 2.17, 95% CI 1.21-3.13, p < 0.001). Summary receiving characteristics curve analysis showed a good diagnostic accuracy of SAA for the presence of RDs (area under the curve = 0.81, 95% CI 0.78-0.84). The effect size of the differences in SAA concentrations between RD patients and controls was significantly associated with sex, body mass index, type of RD, and study country. Pending the conduct of prospective studies in different types of RDs, the results of this systematic review and meta-analysis suggest that SAA is a promising biomarker for the diagnosis of RDs and active disease.

Phenotyping by persistent inflammation in systemic sclerosis associated interstitial lung disease: a EUSTAR database analysis

BACKGROUND

Systemic sclerosis (SSc) is a heterogeneous disease with frequently associated interstitial lung disease (SSc-ILD). We aimed to determine the prognostic potential of phenotyping patients with SSc and SSc-ILD by inflammation and to describe disease trajectories stratified by inflammation and immunosuppressive treatment.

METHODS

Patients from the European Scleroderma Trials and Research (EUSTAR) group cohort were allocated to persistent inflammatory, intermediate and non-inflammatory phenotypes if C-reactive protein (CRP) levels were ≥5 mg/L at ≥80%, at 20-80% and at <20% of visits, respectively. Cox regression models were used to analyse mortality risk and mixed effect models to describe trajectories of FVC and diffusing capacity for carbon monoxide (DLCO) %-predicted stratified by inflammation and immunosuppressive treatment.

RESULTS

2971 patients with SSc and 1171 patients with SSc-ILD had at least three CRP measurements available. Patients with SSc-ILD with a persistent inflammatory phenotype had a 6.7 times higher risk of mortality within 5 years compared with those with a persistent non-inflammatory phenotype (95% CI 3 to 15). In the inflammatory phenotype, FVC %-predicted was declining without (-1.11 (95% CI -2.14 to -0.08)/year), but stable with immunosuppressive treatment (-0.00 (95% CI -0.92 to 0.92)/year). In the non-inflammatory phenotype, patients with and without immunosuppressive treatment had a significant decline in FVC %-predicted, which was more pronounced in those with immunosuppressive treatment (-1.26 (95% CI -1.87 to -0.64) and -0.84 (95% CI -1.35 to -0.33)/year, respectively).

CONCLUSIONS

Phenotyping by persistent inflammation provides valuable prognostic information, independent of demographics, disease duration, cutaneous subtype, treatment and SSc-ILD severity. The findings from this study support early immunosuppressive treatment in patients with SSc-ILD with persistent inflammation.

The role of neutrophil extracellular traps and proinflammatory damage-associated molecular patterns in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are a group of systemic autoimmune diseases characterized by immune-mediated muscle injury. Abnormal neutrophil extracellular traps (NETs) can be used as a biomarker of IIM disease activity, but the mechanism of NET involvement in IIMs needs to be elucidated. Important components of NETs, including high-mobility group box 1, DNA, histones, extracellular matrix, serum amyloid A, and S100A8/A9, act as damage-associated molecular patterns (DAMPs) to promote inflammation in IIMs. NETs can act on different cells to release large amounts of cytokines and activate the inflammasome, which can subsequently aggravate the inflammatory response. Based on the idea that NETs may be proinflammatory DAMPs of IIMs, we describe the role of NETs, DAMPs, and their interaction in the pathogenesis of IIMs and discuss the possible targeted treatment strategies in IIMs.

Toll-like receptor triggering in systemic sclerosis: time to target

SSc is an autoimmune disease that has features of vascular abnormalities, inflammation and skin and lung fibrosis. Toll-like receptors (TLRs) are sentinel receptors that serve to recognize pathogens or internal danger signals leading to downstream signalling pathways that ultimately lead to inflammation and modification of adaptive immunity. Inflammation and fibrosis appear intricately connected in this disease and TLR ligation on fibroblasts can directly activate these cells to produce copious amounts of collagen, a hallmark of disease. The presence of damage-associated molecular patterns in association with fibrosis has been highlighted. Given their prominent role in disease, this review discusses the evidence of their expression and role in disease pathogenesis and possible therapeutic intervention to mitigate fibrosis.

Acute Phase Reactants: Relevance in Dermatology

Acute phase reactants (APRs) are a heterogeneous group of plasma proteins whose concentration either increases or decreases by at least 25% during an inflammatory process. The conditions that commonly lead to acute phase response are infection, trauma, burns, tissue infarction, inflammatory conditions, and advanced malignancy. APRs are elevated in all infective conditions. In skin and soft tissue infection, the levels of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) help to predict the severity of infection. Procalcitonin can be used to differentiate between viral and bacterial infections. During active stages of systemic lupus erythematosus (SLE), ESR is elevated, but CRP either remains normal or shows only moderate elevation. In the case of superadded bacterial infection in SLE, CRP is elevated. In SLE, ferritin levels are elevated during the active stage of the disease. Serum amyloid antigen (SAA) and CRP levels are significantly higher in patients with early and late stages of diffuse systemic sclerosis. Elevated levels of serum ferritin are seen in rheumatoid arthritis and adult-onset Still's disease. CRP, SAA, and α2-macroglobulin (α ₂M) are elevated in active psoriasis. In severe psoriasis, the ferritin-iron ratio is elevated. In drug-induced maculopapular rash, drug-induced hyperaemic vasculitis, and severe drug-induced cutaneous adverse reactions, CRP levels are elevated during the active stages. Neoplastic diseases in general are accompanied by increased serum ferritin. Further detailed studies are required to explore the clinical significance of APRs in dermatology and the scope of their possible application as a diagnostic tool.

Aptamer-Based Biosensors for the Colorimetric Detection of Blood Biomarkers: Paving the Way to Clinical Laboratory Testing

Clinical diagnostics for human diseases rely largely on enzyme immunoassays for the detection of blood biomarkers. Nevertheless, antibody-based test systems have a number of shortcomings that have stimulated a search for alternative diagnostic assays. Oligonucleotide aptamers are now considered as promising molecular recognizing elements for biosensors (aptasensors) due to their high affinity and specificity of target binding. At the moment, a huge variety of aptasensors have been engineered for the detection of various analytes, especially disease biomarkers. However, despite their great potential and excellent characteristics in model systems, only a few of these aptamer-based assays have been translated into practice as diagnostic kits. Here, we will review the current progress in the engineering of aptamer-based colorimetric assays as the most suitable format for clinical lab diagnostics. In particular, we will focus on aptasensors for the detection of blood biomarkers of cardiovascular, malignant, and neurodegenerative diseases along with common inflammation biomarkers. We will also analyze the main obstacles that have to be overcome before aptamer test systems can become tantamount to ELISA for clinical diagnosis purposes.

Tuning Monocytes and Macrophages for Personalized Therapy and Diagnostic Challenge in Rheumatoid Arthritis

Monocytes/macrophages play a central role in chronic inflammatory disorders, including rheumatoid arthritis (RA). Activation of these cells results in the production of various mediators responsible for inflammation and RA pathogenesis. On the other hand, the depletion of macrophages using specific antibodies or chemical agents can prevent their synovial tissue infiltration and subsequently attenuates inflammation. Their plasticity is a major feature that helps the switch from a pro-inflammatory phenotype (M1) to an anti-inflammatory state (M2). Therefore, understanding the precise strategy targeting pro-inflammatory monocytes/macrophages should be a powerful way of inhibiting chronic inflammation and bone erosion. In this review, we demonstrate potential consequences of different epigenetic regulations on inflammatory cytokines production by monocytes. In addition, we present unique profiles of monocytes/macrophages contributing to identification of new biomarkers of disease activity or predicting treatment response in RA. We also outline novel approaches of tuning monocytes/macrophages by biologic drugs, small molecules or by other therapeutic modalities to reduce arthritis. Finally, the importance of cellular heterogeneity of monocytes/macrophages is highlighted by single-cell technologies, which leads to the design of cell-specific therapeutic protocols for personalized medicine in RA in the future.

Transcriptome analysis reveals key genes modulated by ALK5 inhibition in a bleomycin model of systemic sclerosis

Objective

SSc is a rheumatic autoimmune disease affecting roughly 20 000 people worldwide and characterized by excessive collagen accumulation in the skin and internal organs. Despite the high morbidity and mortality associated with SSc, there are no approved disease-modifying agents. Our objective in this study was to explore transcriptomic and model-based drug discovery approaches for SSc.

Methods

In this study, we explored the molecular basis for SSc pathogenesis in a well-studied mouse model of scleroderma. We profiled the skin and lung transcriptomes of mice at multiple timepoints, analysing the differential gene expression that underscores the development and resolution of bleomycin-induced fibrosis.

Results

We observed shared expression signatures of upregulation and downregulation in fibrotic skin and lung tissue, and observed significant upregulation of key pro-fibrotic genes including GDF15, Saa3, Cxcl10, Spp1 and Timp1. To identify changes in gene expression in responses to anti-fibrotic therapy, we assessed the effect of TGF-β pathway inhibition via oral ALK5 (TGF-β receptor I) inhibitor SB525334 and observed a time-lagged response in the lung relative to skin. We also implemented a machine learning algorithm that showed promise at predicting lung function using transcriptome data from both skin and lung biopsies.

Conclusion

This study provides the most comprehensive look at the gene expression dynamics of an animal model of SSc to date, provides a rich dataset for future comparative fibrotic disease research, and helps refine our understanding of pathways at work during SSc pathogenesis and intervention.

Association of soluble urokinase plasminogen activator receptor levels with fibrotic and vascular manifestations in systemic sclerosis

OBJECTIVE

We assessed the association of suPAR (soluble urokinase plasminogen activator receptor) plasma levels with fibrotic and vascular manifestations in patients with systemic sclerosis (SSc).

METHODS

suPAR plasma levels were measured in 121 consecutive patients with SSc and correlated to pulmonary and vascular features of SSc, including interstitial lung disease as characterized by percentage of predicted CO diffusing capacity (DLco) and forced vital capacity (FVC), pulmonary fibrosis by computed tomography, and pulmonary arterial hypertension, telangiectasias, and digital ulcers.

RESULTS

Overall, 121 SSc patients (84% females; mean age, 57 ± 12 [range: 22-79] years) were enrolled; 35% had diffuse cutaneous SSc. suPAR plasma levels ranged from 1.3-10.2 [median: 2.9 (p25-p75: 2.3-3.9)] ng/mL. Log(suPAR) levels correlated with DLco (r = -0.41, p <0.0001) and FVC (r = -0.26, p = 0.004), also when adjusted for age, sex, and pulmonary hypertension. A suPAR cut-off level of >2.5 ng/mL showed a sensitivity of 91% for identifying patients with either DLco <50% or FVC < 60% of the predicted values. Similarly, 19 (90%) had a suPAR >2.5 ng/mL among those diagnosed with pulmonary fibrosis vs. 59 (60%) among those who did not (p = 0.008). suPAR values were not associated with vascular manifestations.

CONCLUSION

suPAR levels strongly correlated with pulmonary involvement in SSc. Future studies should test if suPAR estimation can be used for surveillance of severe pulmonary involvement in SSc.

Serum Amyloid A in Inflammatory Rheumatic Diseases: A Compendious Review of a Renowned Biomarker

Serum amyloid A (SAA) is an acute phase protein with a significant importance for patients with inflammatory rheumatic diseases (IRD). The central role of SAA in pathogenesis of IRD has been confirmed by recent discoveries, including its involvement in the activation of the inflammasome cascade and recruitment of interleukin 17 producing T helper cells. Clinical utility of SAA in IRD was originally evaluated nearly half a century ago. From the first findings, it was clear that SAA could be used for evaluating disease severity and monitoring disease activity in patients with rheumatoid arthritis and secondary amyloidosis. However, cost-effective and more easily applicable markers, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), overwhelmed its use in clinical practice. In the light of emerging evidences, SAA has been discerned as a more sensitive biomarker in a wide spectrum of IRD, especially in case of subclinical inflammation. Furthermore, a growing number of studies are confirming the advantages of SAA over many other biomarkers in predicting and monitoring response to biological immunotherapy in IRD patients. Arising scientific discoveries regarding the role of SAA, as well as delineating SAA and its isoforms as the most sensitive biomarkers in various IRD by recently developing proteomic techniques are encouraging the revival of its clinical use. Finally, the most recent findings have shown that SAA is a biomarker of severe Coronavirus disease 2019 (COVID-19). The aim of this review is to discuss the SAA-involving immune system network with emphasis on mechanisms relevant for IRD, as well as usefulness of SAA as a biomarker in various IRD. Therefore, over a hundred original papers were collected through an extensive PubMed and Scopus databases search. These recently arising insights will hopefully lead to a better management of IRD patients and might even inspire the development of new therapeutic strategies with SAA as a target.

Aptamers for Proteins Associated with Rheumatic Diseases: Progress, Challenges, and Prospects of Diagnostic and Therapeutic Applications

Nucleic acid aptamers capable of affine and specific binding to their molecular targets have now established themselves as a very promising alternative to monoclonal antibodies for diagnostic and therapeutic applications. Although the main focus in aptamers’ research and development for biomedicine is made on cardiovascular, infectious, and malignant diseases, the use of aptamers as therapeutic or diagnostic tools in the context of rheumatic diseases is no less important. In this review, we consider the main features of aptamers that make them valuable molecular tools for rheumatologists, and summarize the studies on the selection and application of aptamers for protein biomarkers associated with rheumatic diseases. We discuss the progress in the development of aptamer-based diagnostic assays and targeted therapeutics for rheumatic disorders, future prospects in the field, and issues that have yet to be addressed.

Potential Biomarkers in Systemic Sclerosis: A Literature Review and Update

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by dysregulation of the immune system, vascular damage, and fibrosis of the skin and internal organs. Patients with SSc show a heterogeneous phenotype and a range of clinical courses. Therefore, biomarkers that are helpful for precise diagnosis, prediction of clinical course, and evaluation of the therapeutic responsiveness of disease are required in clinical practice. SSc-specific autoantibodies are currently used for diagnosis and prediction of clinical features, as other biomarkers have not yet been fully vetted. Krebs von den Lungen-6 (KL-6), surfactant protein-D (SP-D), and CCL18 have been considered as serum biomarkers of SSc-related interstitial lung disease. Moreover, levels of circulating brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) can provide diagnostic information and indicate the severity of pulmonary arterial hypertension. Assessment of several serum/plasma cytokines, chemokines, growth factors, adhesion molecules, and other molecules may also reflect the activity or progression of fibrosis and vascular involvement in affected organs. Recently, microRNAs have also been implicated as possible circulating indicators of SSc. In this review, we focus on several potential SSc biomarkers and discuss their clinical utility.

Biomarkers in systemic sclerosis-associated interstitial lung disease: review of the literature

SSc is a rare disease of unknown origin associated with multiple organ involvement. One of the major complications that drives the mortality of SSc patients is interstitial lung disease. The course of SSc-interstitial lung disease progression has a wide spectrum. Since the treatment is based on aggressive immunosuppression it should not be given to stable or non-progressing disease. The correct identification of disease with high risk of progression remains a challenge for early therapeutic intervention, and biomarkers remain urgently needed. In fact, eight categories of biomarkers have been identified and classified according to the different biological pathways involved. The purpose of this article is to describe the main biomarkers thought to be of interest with clinical value in the diagnosis and prognosis of SSc-interstitial lung disease.

Serum amyloid A: A potential biomarker of lung disorders

Serum amyloid A is an acute-phase protein with multiple immunological functions. Serum amyloid A is involved in lipid metabolism, inflammatory reactions, granuloma formation, and cancerogenesis. Additionally, serum amyloid A is involved in the pathogenesis of different autoimmune lung diseases. The levels of serum amyloid A has been evaluated in biological fluids of patients with different lung diseases, including autoimmune disorders, chronic obstructive pulmonary diseases, obstructive sleep apnea syndrome, sarcoidosis, asthma, lung cancer, and other lung disorders, such as idiopathic pulmonary fibrosis, tuberculosis, radiation pneumonitis, and cystic fibrosis. This review focuses on the cellular and molecular interactions of serum amyloid A in different lung diseases and suggests this acute-phase protein as a prognostic marker.

Rituximab therapy is more effective than cyclophosphamide therapy for Japanese patients with anti-topoisomerase I-positive systemic sclerosis-associated interstitial lung disease

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is the most frequent cause of death for SSc but there is still no sufficient treatment available. Although cyclophosphamide (CYC) therapy is a common treatment which has shown statistical efficacy against SSc-ILD to date, its effects are temporary and not enough. Rituximab (RTX), the anti-CD20 monoclonal antibody, has recently shown efficacy in many autoimmune diseases. In SSc-ILD, RTX is also considered to be one of the novel treatment candidates. However, studies of SSc-ILD in Japanese treated with RTX have only a few case reports. Therefore, in this study, we retrospectively compared nine patients treated with RTX and 30 patients treated with CYC to investigate the efficacy of RTX treatment for Japanese anti-topoisomerase I-positive SSc-ILD patients. At the 24-month evaluation, the improvement rates of percent predicted of forced vital capacity and percent predicted of diffusing capacity of the lung carbon monoxide in the RTX-treated group were significantly higher than those in the CYC-treated group (20.6 ± 8.8% vs 1.1 ± 3.9%; P < 0.05 and 34.0 ± 6.0% vs -1.5 ± 2.8%; P < 0.01, respectively). In addition, skin thickness scores also showed a marked improvement from 13.5 points before the start of treatment to 5.8 points after 24 months by RTX therapy (P < 0.05). These results suggest that RTX treatment is more effective for Japanese SSc-ILD patients than CYC treatment. In the future, it is expected that large-scale clinical trials will show the usefulness of RTX treatment for SSc-ILD.

Study of role of serum amyloid A (SAA) as a marker of disease activity in juvenile idiopathic arthritis

Background:

Role of serum amyloid A (SAA) protein as a biomarker for the disease activity in juvenile idiopathic arthritis (JIA) has not been explored. This study was done to find its role as marker of disease activity in JIA.

Methods:

A case–control study with 50 newly diagnosed cases of JIA of all subtypes and 40 healthy controls was done. Serum amyloid A (SAA), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were measured in both patients and healthy controls. Quantitative measurement of SAA level was measured by using standard human SAA enzyme-linked immunosorbent assay (ELISA). Disease activity was assessed clinically and by ultrasonography (USG) score determined by examining eight large joints (bilateral elbow, wrist, knee, ankle). Serum SAA levels were found significantly higher in JIA patients as compared with healthy controls (P < 0.001). Significant positive correlations were found between SAA with presence of active joints (r = 0.64, P < 0.001), ESR (r = 0.39, P < 0.05), and CRP (r = 0.36, P < 0.05). However, significant correlations was not found between ESR and the presence of active joints (r = 0.21, P = 0.225) and between CRP and the presence of active joints (r = 0.034, P = 0.855). The mean USG score of patients with increased SAA level was significantly higher than that of patients with normal SAA level (P < 0.05).

Conclusion:

A significant increase in SAA levels was found in JIA patients with strong positive correlation between SAA level and JIA disease activity. The study discerned SAA to be a more sensitive laboratory marker than ESR and CRP for evaluating the presence of active joints.