Serum calprotectin--a promising diagnostic marker for adult-onset Still's disease

Expression of S100A8 protein on B cells is associated with disease activity in patients with systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an intractable disease characterized by autoantibody production and autoreactive B and T cell proliferation. Although several studies have revealed multiple genetic and environmental associations, the underlying mechanisms remain unknown.

METHODS

We performed proteomics and transcriptomics using liquid chromatography-mass spectrometry and DNA microarray, using peripheral blood B cells from patients with SLE, and healthy controls (HC). We explored molecules associated with the pathophysiology of SLE by flow cytometry and B cell stimulation assay.

RESULTS

We identified for the first time that expression of both S100A8 protein and mRNA were markedly upregulated in SLE B cells. The results obtained using flow cytometry showed that S100A8 was highly expressed on the surface of B cells of patients with active SLE (MFI; HC 102.5 ± 5.97, stable SLE 111.4 ± 12.87, active SLE 586.9 ± 142.9), and S100A8 on the cell surface was decreased after treatment (MFI; pre-treat 1094.5 ± 355.38, post-treat 492.25 ± 247.39); therefore, it is suggested that S100A8 may be a marker for disease activity. The mRNA expression of S100A8 was particularly upregulated in memory B cells of SLE (56.68 fold higher than HC), suggesting that S100A8 may be mainly secreted by memory B cells in the pathogenesis of SLE.

CONCLUSIONS

Our results imply that the S100A8 proteins secreted from memory B cells may stimulate granulocytes and monocytes through pattern recognition receptors, activate the innate immune system, and are involved in the pathogenesis of SLE.

Calprotectin as a diagnostic marker for sepsis: A meta-analysis

Introduction

Sepsis is a life-threatening condition, and biomarkers are needed to diagnose sepsis fast and accurately. We aimed to perform this meta-analysis to investigate the diagnostic value of calprotectin on sepsis in critically ill patients.

Methods

The investigators searched MEDLINE, Embase, Web of Science and Cochrane Library. Studies were included if they assessed the diagnostic accuracy of serum calprotectin for sepsis in intensive care unit (ICU). We estimated its diagnostic value and explored the source of heterogeneity. The bivariate model and the hierarchical summary receiver operating characteristic (HSROC) curve were used in the meta-analysis.

Results

Six records assessing 821 patients were included in this meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio (PLR), and diagnostic odds ratio (DOR) were separately as 0.77, 0.85, 5.20, 0.27, respectively. The Fagan's nomogram showed post-test probabilities of 91% and 35% for positive and negative outcomes, respectively. Subgroup analysis indicated that sepsis definition could be a possible source of heterogeneity, but there's no sufficient data to investigate sepsis-3 definition. Sensitivity analysis suggested that two studies could affect the stability of pooled results.

Conclusion

On the basis of our meta-analysis, calprotectin is a helpful marker for early diagnosis of sepsis on ICU admission.

The value of fecal calprotectin in Clostridioides difficile infection: A systematic review

As a marker of inflammation, calprotectin has potential application value in a variety of inflammatory diseases, such as arthritis and bacterial infections. Clostridioides difficile infection (CDI) is an infectious disease that causes intestinal damage and inflammation. This systematic review aims to determine whether fecal calprotectin has application value in CDI. Nine databases were searched from inception to 6 June 2022, and 17 studies were included. These studies were divided into four groups according to their content. Generally speaking, fecal calprotectin is not an ideal indicator for the diagnosis and prognosis prediction of CDI but may serve as a potential indicator for assessing disease severity and as a readily detectable marker for CDI screening. In addition, patients in need of treatment or with detectable toxins in stool may tend to have higher levels of fecal calprotectin. In summary, fecal calprotectin has some potential application value in CDI. However, further studies are needed to verify these findings and determine the reliability of calprotectin as a biomarker for CDI.

Strategy and Challenges of Paraclinical Examinations in Adult-Onset Still’s Disease

Adult-onset Still’s disease is a complex autoinflammatory disease with a multifactorial etiology. Its presentation is less stereotypical than that of a monogenic autoinflammatory disease and is actually relatively common with few specific signs. To avoid under- or over-prescription of complementary examinations, it is useful to advance in a structured manner, taking into consideration the actual added value of each supplemental examination. In this review, we detail the different complementary tests used in adult Still’s disease. We consider them from three different angles: positive diagnostic approach, the differential diagnosis, and the screening for complications of the disease. After discussing the various tests at our disposal, we look at the classical diagnostic strategy in order to propose a structured algorithm that can be used in clinical practice. We conclude with the prospects of new complementary examinations, which could in the future modify the management of patients.

Calprotectin in viral systemic infections-COVID-19 versus hepatitis C virus

This study aims to evaluate differences in serum and fecal calprotectin in patients with HCV chronic hepatitis and COVID-19 infection and compare them to a control group. This observational study was performed between April 2020 and October 2020 in a single Internal Medicine center. We determined serum and fecal calprotectin, as well as levels of transaminases, C-reactive protein, ferritin, in 25 patients with COVID-19 infection, 30 patients with active HCV chronic infection and 38 patients with cured HCV infection. Serum levels of ALT, AST, C-reactive protein and ferritin were significantly higher in patients with COVID-19 infection (mean values of 127 IU/mL, 135 IU/mL, 123 mg/L and 1034 ng/mL, respectively) than in patients with active HCV infection (mean values of 68 IU/mL, 51 IU/mL, 17 mg/L and 528 ng/mL, respectively) or in patients with cured HCV infection (37 IU/mL, 29 IU/mL, 3.4 mg/L and 274 ng/mL, respectively). Also, serum and fecal calprotectin had increased concentrations in patients with COVID-19 (7.3 µg/mL and 394 µg/mg) versus patients with active hepatitis (2.4 µg/mL and 217 µg/mg) and patients with cured hepatitis (1.2 µg/mL and 38 µg/mg). Values were significantly higher in patients with digestive symptoms related to COVID-19. Serum and fecal calprotectin can be used as inflammatory markers in patients with active viral infections. In COVID-19, calprotectin concentrations can be correlated to the severity of disease, particularly in patients with digestive symptoms.

Adult-Onset Still's Disease: Novel Biomarkers of Specific Subsets, Disease Activity, and Relapsing Forms

Adult-onset Still’s disease (AOSD) is a systemic inflammatory disease of unknown etiology. Recent studies have demonstrated that the hallmark of AOSD is a cytokine storm, which is characterized by the excessive production of interleukin (IL)-1, IL-6, IL-18, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ), suggesting how pro-inflammatory cytokines play an important role in the pathogenesis of this disease. Actually, a certain proportion of patients (around 17–32%) with severe clinical symptoms achieves only partial remission or is resistant to both first-line corticosteroids and second-line DMARDs. These patients are defined as refractory AOSD patients, requiring higher dosage glucocorticoids, longer treatment duration, or the simultaneous introduction of immunosuppressive drugs, further leading to AOSD relapses. In this narrative review, we will analyze the latest literature data to unravel potential pathogenetic factors associated with specific patterns of AOSD disease or relapses in order to identify biomarkers that may guide clinical decisions, eventually leading to new therapeutic options.

An Update on the Pathogenic Role of Neutrophils in Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Neutrophils are innate immune phagocytes that play a key role in immune defense against invading pathogens. The main offensive mechanisms of neutrophils are the phagocytosis of pathogens, release of granules, and production of cytokines. The formation of neutrophil extracellular traps (NETs) has been described as a novel defense mechanism in the literature. NETs are a network of fibers assembled from chromatin deoxyribonucleic acid, histones, and neutrophil granule proteins that have the ability to kill pathogens, while they can also cause toxic effects in hosts. Activated neutrophils with NET formation stimulate autoimmune responses related to a wide range of inflammatory autoimmune diseases by exposing autoantigens in susceptible individuals. The association between increased NET formation and autoimmunity was first reported in antineutrophil cytoplasmic antibody-related vasculitis, and the role of NETs in various diseases, including systemic lupus erythematosus, rheumatoid arthritis, and psoriasis, has since been elucidated in research. Herein, we discuss the mechanistic role of neutrophils, including NETs, in the pathogenesis of systemic juvenile idiopathic arthritis (SJIA) and adult-onset Still’s disease (AOSD), and provide their clinical values as biomarkers for monitoring and prognosis.

Adult-onset Still's disease in focus: Clinical manifestations, diagnosis, treatment, and unmet needs in the era of targeted therapies

BACKGROUND

Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder of unknown etiology, characterized by a clinical triad of high spiking fever, arthralgia (± arthritis), and evanescent skin rash. Management of AOSD poses several challenges, including difficulty in diagnosis and limited therapeutic options. In this review, we examined whether AOSD and systemic juvenile idiopathic arthritis (SJIA) represent a continuum of the same disease. We also explored the latest available evidence related to prevalence, clinical and laboratory manifestations, complications, diagnostic challenges, novel biomarkers, and treatment options in the era of biologics and identified the unmet needs of patients with AOSD.

METHODS

A comprehensive systematic literature search was performed in the Embase and MEDLINE (via PubMed) literature databases. The search was limited to human studies published in English from inception up to March 2020. Additionally, abstracts presented at various conferences were screened and hand searches were performed. Publications were processed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

A total of 123 publications were identified through the literature search, majority of which were case series and retrospective observational studies. AOSD and SJIA are widely considered part of the same disease spectrum owing to similarities in their clinical and biological features. The clinical presentation of AOSD is highly variable, accompanied by a broad spectrum of disease manifestations. Recent evidence suggests that the AOSD disease course can be classified into two distinct categories: "systemic" and "articular." Furthermore, AOSD patients may experience various life-threatening complications, such as macrophage activation syndrome - reported in as high as 23% of AOSD patients and considered to be the most severe complication characterized by a high mortality rate. The ambiguity in presentation and lack of serologic markers make the diagnosis of AOSD difficult, often leading to a delay in diagnosis. Given these limitations, the Yamaguchi and Fautrel criteria are the most widely used diagnostic tools in clinical practice. It has been observed that a clinical diagnosis of AOSD is generally reached by exclusion while investigating a patient with fever of unknown origin. Recent advances have demonstrated a major role of proinflammatory cytokines, such as interleukin (IL)-1, IL-6, IL-18, and IL-37, and other biomarkers in the pathogenesis and management of AOSD. Owing to the rarity of the disease, there are very limited clinical trials evaluating management strategies for AOSD. The current AOSD treatment paradigm includes non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids initially, conventional synthetic disease-modifying anti-rheumatic drugs in steroid-refractory patients, and biologics in those resistant to conventional treatment. Only a few country-specific guidelines for the management of AOSD have been published, and a treat-to-target approach, as previously recommended for SJIA, is still lacking. Canakinumab is the only FDA-approved biologic for the treatment of AOSD.

CONCLUSION

Emerging evidence supports that AOSD and SJIA represent a continuum of the same disease entity. Despite advancements in the understanding of AOSD, it continues to pose a substantial burden on patients and the healthcare systems, and substantial unmet needs exist across key domains such as the pathway to diagnosis, use of biomarkers in clinical practice, and standardized treatment strategies. Further research and collaboration is crucial for optimizing the diagnosis and management of AOSD patients.

Circulating calprotectin as biomarker in neutrophil-related inflammation: Pre-analytical recommendations and reference values according to sample type

BACKGROUND

Calprotectin (CLP) is a promising biomarker for the evaluation of neutrophil-related inflammation. Our aim was to establish reference values for circulating CLP in different sample types and to study the effect of pre-analytical variables.

METHODS

Reference values were determined in 100 healthy individuals. Pre-analytical variables were evaluated in 10 healthy controls and four rheumatoid arthritis patients with active disease and covered sample type (serum with/without gel separator, heparin, EDTA and citrate plasma), pre-centrifugation time (<2 h, 6 h, 24 h), storage condition (2-8 °C, 18-25 °C, 30 °C) and storage time (24 h, 72 h, 7 days). CLP measurements were performed with the EliA™Calprotectin 2 assay on Phadia™200 (Thermo Fisher Scientific).

RESULTS

In healthy controls, baseline CLP concentrations in serum were more than double the concentration in EDTA and citrate plasma (0.909 µg/mL versus 0.259 µg/mL and 0.261 µg/mL respectively). Heparin, EDTA and citrate stabilized CLP concentrations for up to 6 h before centrifugation, whereas significant increases in CLP levels were observed when serum was left untreated during that time period.

CONCLUSION

Clinical studies on circulating CLP need to apply sample type-specific reference values and decision limits. To obtain reproducible CLP results in serum, more stringent pre-analytical sample handling instructions are needed.

Calprotectin in Lung Diseases

Calprotectin (CLP) is a heterodimer formed by two S-100 calcium-binding cytosolic proteins, S100A8 and S100A9. It is a multifunctional protein expressed mainly by neutrophils and released extracellularly by activated or damaged cells mediating a broad range of physiological and pathological responses. It has been more than 20 years since the implication of S100A8/A9 in the inflammatory process was shown; however, the evaluation of its role in the pathogenesis of respiratory diseases or its usefulness as a biomarker for the appropriate diagnosis and prognosis of lung diseases have only gained attention in recent years. This review aimed to provide current knowledge regarding the potential role of CLP in the pathophysiology of lung diseases and describe how this knowledge is, up until now, translated into daily clinical practice. CLP is involved in numerous cellular processes in lung health and disease. In addition to its anti-microbial functions, CLP also serves as a molecule with pro- and anti-tumor properties related to cell survival and growth, angiogenesis, DNA damage response, and the remodeling of the extracellular matrix. The findings of this review potentially introduce CLP in daily clinical practice within the spectrum of respiratory diseases.

The Role of Plasma Calprotectin in Non-infectious Uveitis

PURPOSE

To investigate the role of plasma calprotectin in non-infectious uveitis.

METHODS

This is an observational both cross-sectional and prospective study. Patients with active non-infectious uveitis were recruited as well as nonuveitic controls. Plasma calprotectin was determined and an ophthalmological examination was performed for both patients and controls. Independent variables possibly influencing levels of plasma calprotectin were recorded and analyzed. Categorical variables were compared by chi-square test (applying correction by continuity if necessary). T-test (or Kruskal-Wallis when appropriate) was used to compare averages. Multiple linear regression analysis was used to assess relationship between plasma calprotectin levels and independent variables. Spearman coefficient was calculated in order to establish correlation between plasma calprotectin and anterior chamber cell grading. Changes in plasma calprotectin levels between the flare beginning and its resolution were determined with mixed model for repeated measures. R software (version 3.6.0) was used to perform the statistical analysis.

RESULTS

We included 74 patients and 40 controls in the cross-sectional study. Plasma calprotectin levels were higher in uveitis patients compared to those of controls (p = .003), being higher in younger patients and patients with posterior uveitis. No correlation between calprotectin and anterior chamber inflammation degree was found (p = .198). For the prospective study, we included 36 patients. We found no significant differences in calprotectin levels between active and inactive uveitis (p = .344).

CONCLUSIONS

Plasma calprotectin levels are elevated in uveitis patients and are influenced by age and anatomical location of uveitis. Further investigation is needed to assess the relationship between calprotectin and uveitis activity.

Roles of Interactions Between Toll-Like Receptors and Their Endogenous Ligands in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Systemic juvenile idiopathic arthritis (JIA) and adult-onset Still’s disease (AOSD) are systemic inflammatory disorders that manifest as high-spiking fever, joint pain, evanescent skin rash, and organomegaly. Their pathogenesis is unclear, but inflammation is triggered by activation of the innate immune system with aberrant production of proinflammatory cytokines. Along with extrinsic factors, intrinsic pathways can trigger an unexpected immune response. Damage-associated molecular patterns (DAMPs) induce the activation of innate immune cells, leading to sterile inflammation in systemic JIA and AOSD. These endogenous proteins interact with Toll-like receptors (TLRs), which are pattern recognition receptors, and mediate immune signaling following stimulation by pathogen-associated molecular patterns and DAMPs. Several DAMPs, such as S100 proteins, play a role in the development or severity of systemic JIA and AOSD, in which their interactions with TLRs are altered. Also, the expression levels of genes encoding DAMPs contribute to the susceptibility to systemic JIA and AOSD. Herein, we review reports that TLR and DAMP signaling initiates and/or maintains the inflammatory response in systemic JIA and AOSD, and their correlations with the clinical characteristics of those diseases. In addition, we assess their utility as biomarkers or therapeutics for systemic JIA and AOSD.

Neutrophil calprotectin identifies severe pulmonary disease in COVID-19

Severe cases of coronavirus disease 2019 (COVID-19) are regularly complicated by respiratory failure. Although it has been suggested that elevated levels of blood neutrophils associate with worsening oxygenation in COVID-19, it is unknown whether neutrophils are drivers of the thrombo-inflammatory storm or simple bystanders. To better understand the potential role of neutrophils in COVID-19, we measured levels of the neutrophil activation marker S100A8/A9 (calprotectin) in hospitalized patients and determined its relationship to severity of illness and respiratory status. Patients with COVID-19 (n = 172) had markedly elevated levels of calprotectin in their blood. Calprotectin tracked with other acute phase reactants including C-reactive protein, ferritin, lactate dehydrogenase, and absolute neutrophil count, but was superior in identifying patients requiring mechanical ventilation. In longitudinal samples, calprotectin rose as oxygenation worsened. When tested on day 1 or 2 of hospitalization (n = 94 patients), calprotectin levels were significantly higher in patients who progressed to severe COVID-19 requiring mechanical ventilation (8039 ± 7031 ng/ml, n = 32) as compared to those who remained free of intubation (3365 ± 3146, P < 0.0001). In summary, serum calprotectin levels track closely with current and future COVID-19 severity, implicating neutrophils as potential perpetuators of inflammation and respiratory compromise in COVID-19.

Case Report: Adult Still's Disease in an Alemtuzumab-Treated Multiple Sclerosis Patient

Background

Autoimmune adverse events are the most relevant risks of alemtuzumab therapy. We present a patient with relapsing-remitting multiple sclerosis, who developed adult-onset Still's disease (AOSD) following alemtuzumab treatment.

Case Presentation

The patient suffered from sore throat, swallowing difficulties, high spiking quotidian fever, generalized skin rash, arthritis, and myalgia 2 months after the second course of alemtuzumab. Laboratory tests revealed elevated acute-phase reactants, anemia, neutrophilic leukocytosis, and thrombocytosis. Serum calprotectin, interleukin-2, and interleukin-6 levels were strongly increased. Autoimmune, rheumatic, neoplastic, infectious, and granulomatous disorders were excluded. The NLRP1 and NLRP3 gene test, which was performed under the presumption of a cryopyrin-associated autoinflammatory syndrome, was negative. Based on the Yamaguchi and Fautrel criteria, and supported by the histological findings from a skin biopsy of the rash, the diagnosis of AOSD was established. Therapy with the anti-IL-1 agent (anakinra) led to a significant improvement of symptoms and blood parameters. However, anakinra had to be converted to rituximab due to generalized drug eruption. Following therapy with rituximab, the patient has fully recovered.

Conclusion

The current case highlights AOSD as another rare and potentially life-threatening secondary autoinflammatory/autoimmune event following alemtuzumab treatment.

Neutrophil calprotectin identifies severe pulmonary disease in COVID-19

Severe cases of coronavirus disease 2019 (COVID-19) are regularly complicated by respiratory failure. While it has been suggested that elevated levels of blood neutrophils associate with worsening oxygenation in COVID-19, it is unknown whether neutrophils are drivers of the thrombo-inflammatory storm or simple bystanders. To better understand the potential role of neutrophils in COVID-19, we measured levels of the neutrophil activation marker S100A8/A9 (calprotectin) in hospitalized patients and determined its relationship to severity of illness and respiratory status. Patients with COVID-19 (n=172) had markedly elevated levels of calprotectin in their blood. Calprotectin tracked with other acute phase reactants including C-reactive protein, ferritin, lactate dehydrogenase, and absolute neutrophil count, but was superior in identifying patients requiring mechanical ventilation. In longitudinal samples, calprotectin rose as oxygenation worsened. When tested on day 1 or 2 of hospitalization (n=94 patients), calprotectin levels were significantly higher in patients who progressed to severe COVID-19 requiring mechanical ventilation (8039 +/- 7031 ng/ml, n=32) as compared to those who remained free of intubation (3365 +/- 3146, p<0.0001). In summary, serum calprotectin levels track closely with current and future COVID-19 severity, implicating neutrophils as potential perpetuators of inflammation and respiratory compromise in COVID-19.

Can Calprotectin Show Subclinical Inflammation in Familial Mediterranean Fever Patients?

BACKGROUND

Familial Mediterranean fever (FMF) is an autoinflammatory disease that has self-limiting inflammatory attacks during polyserositis. Hepcidin is a protein, and interleukin-6 stimulation increases hepcidin levels. Calprotectin (CLP) is a recently defined cytokine released from monocytes and neutrophils in response to tissue trauma and inflammation. There are studies in the literature showing that it can be used as a biomarker in rheumatic diseases such as ankylosing spondylitis and rheumatoid arthritis. Here, we compared the levels of hepcidin and CLP in healthy individuals and FMF patients during an attack-free period and show its relation to genetic mutations.

METHODS

This is a cross-sectional study. Between July 2017 and December 2017, 60 patients diagnosed with FMF an admitted to the Cumhuriyet University Faculty of Medicine Department of Internal Medicine Rheumatology as well as 60 healthy volunteers without any rheumatic, systemic, or metabolic diseases were enrolled in this study. Blood was collected from a peripheral vein to measure serum CLP and hepcidin levels. Blood tests were examined by ELISA; the study protocol was approved by the local ethics committee.

RESULTS

Median serum hepcidin level was 468.1 (210.3-807.8) pg/mL in FMF group and 890.0 (495.0-1,716.9) pg/mL in the healthy control (HC) group. There was a statistically significant difference between the two groups (P < 0.001). The median serum levels of CLP in the FMF group were measured as 1,331.4 (969.3-1,584.6 pg/mL and 73.8(45.0-147.9) pg/mL in the HC group. There was a statistically significant difference between the two groups (P < 0.001). Receiver operating characteristic analysis showed that the sensitivity was 66.7% and the specificity was 71.7% at serum hepcidin < 581.25 pg/mL (P < 0.05); the sensitivity was 96.7% and specificity was 100% at CLP > 238 pg/mL (P < 0.05). There was no significant difference between serum hepcidin and CLP levels in FMF patients with M694V homozygous and M694V heterozygous (P > 0.05). There was no significant difference in serum hepcidin levels between FMF patients with and without arthritis, proteinuria, and amyloidosis (P < 0.05). There was no significant correlation between laboratory findings, gender, age, and serum CLP and hepcidin levels (P > 0.05, r < 0.25).

CONCLUSION

Serum CLP levels in FMF patients during an attack-free period are significantly higher than in the HC groups. Serum hepcidin levels in FMF patients are significantly lower than in the HC group. Low levels of hepcidin may be explained by including FMF patients during an attack-free period in the study. CLP may be an important biomarker in FMF. A better understanding of the role of these biomarkers in the diagnosis of FMF is needed to evaluate the results in a more comprehensive way.

The Role of Calprotectin in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease characterized by inflammatory cell infiltration, high levels of cytokines, and erosion of cartilage and bone in joints. Calprotectin (CLP), as a recently described member of S100 family proteins, is a heterodimeric complex of S100A8 and S100A9. Currently, plenty of studies have indicated significantly increased serum and synovial fluid levels of CLP in patients with RA. It was reported that CLP was related to cell differentiation, migration, apoptosis, and production of pro-inflammatory factors in RA. In addition, there are the positive relationships between serum, synovial CLP and traditional acute phase reactants, disease activity, ultrasound and radiographic progression of joints, and treatment response of RA. In this review, we mainly discuss the role of CLP in the pathogenesis of RA as well as its potential to estimate clinical disease progression of RA patients.

Pathogenesis, disease course, and prognosis of adult-onset Still's disease: an update and review

OBJECTIVE

Adult-onset Still's disease (AOSD) is a rare but clinically well-known polygenic systemic autoinflammatory disease. In this review, we aim to present frontiers in the pathogenesis, clinical features, diagnosis, biomarkers, disease course, prognosis, and treatment in AOSD.

DATA SOURCES

We retrieved information from the PubMed database up to July 2019, using various search terms and relevant words, including AOSD and Still's disease.

STUDY SELECTION

We included data from peer-reviewed journals. Both basic and clinical studies were selected.

RESULTS

Pathogenesis of AOSD involves genetic background, infectious triggers, and immunopathogenesis, mainly the activation of macrophages and neutrophils followed by a cytokine storm. Diagnosis and prognosis evaluation of AOSD is still challenging; therefore, there is an urgent need to identify better biomarkers. Biologic agents, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α antagonists in the treatment of AOSD, have good prospect.

CONCLUSION

This review highlights the advances in pathogenesis, potential biomarkers, disease course, and treatment in AOSD.

The role of damage-associated molecular pattern for pathogenesis and biomarkers in adult-onset Still's disease

Introduction: Adult-onset Still's disease (AOSD) is a systemic inflammatory disease, which presents itself as an adult form of systemic juvenile idiopathic arthritis. Innate immune activation driven by a combination of genetic and environmental factors is the primary mechanism underlying disease pathogenesis in AOSD patients. Few biomarkers have been identified for AOSD diagnosis or for the assessment of disease activity or prediction of clinical outcomes. Damage-associated molecular patterns (DAMPs) can activate innate immunity, resulting in tissue damage. Changes in several DAMPs are associated with disease pathogenesis in AOSD patients. Areas covered: This review describes the role of DAMPs in AOSD pathogenesis and discusses their potential for use as disease biomarkers. Together with overall pathogenesis of AOSD, high-mobility group box-1, advanced glycation end products, S100 proteins, and neutrophil extracellular traps are introduced and discussed in detail. Expert opinion: The activation of macrophages and neutrophils is associated with several DAMPs, causing high concentrations of proinflammatory cytokines in AOSD patients. Involvement of certain DAMPs in AOSD patients is well documented due to the presence of sterile inflammation; however, direct evidence for some DAMPs is lacking. Further research into the role of DAMP molecules in AOSD patients may reveal new biomarkers and provide targets for disease intervention.

Serum calprotectin and ischemia modified albumin levels as markers of disease activity in Behçet's disease

Introduction

Behçet’s disease (BD) is a complex multisystemic inflammatory disorder which is characterized by recurrent attacks of acute inflammation. As there is no universally recognized pathognomonic laboratory marker of BD, its diagnosis is still based on clinical findings.

Aim

To evaluate the role of calprotectin and ischemia modified albumin (IMA) as biomarkers in the assessment of disease activity of BD.

Material and methods

A total of 93 patients with BD and 62 age- and gender-matched healthy controls were included in the study. Disease activity was assessed with the BD Current Activity Form (BDCAF) score. Serum levels of calprotectin, high-sensitivity C-reactive protein (hsCRP) and IMA were measured in the patient and control groups.

Results

Serum levels of calprotectin, IMA and hsCRP in patients with BD were higher than those of the healthy control group (p < 0.001 for all). No correlations between calprotectin and IMA, hsCRP, erythrocyte sedimentation rate, CRP, or BDCAF score were found.

Conclusions

As the calprotectin level are increased in BD patients, it could be a candidate biomarker which plays a role in BD pathogenesis.

Placenta Specific 8 Suppresses IL-18 Production through Regulation of Autophagy and Is Associated with Adult Still Disease

Adult Still disease (ASD) is a systemic disorder of unknown etiology characterized by high spiking fever, rash, and arthritis. The purpose of this study was to identify genes specifically associated with the active phase of the disease. In this study, we have reported that placenta specific 8 (PLAC8) was a newly specific gene involved in ASD. DNA microarray and validation analysis using human monocytes revealed that the expression of PLAC8 was significantly higher in active-ASD patients than in inactive-ASD patients and healthy controls. In ASD, PLAC8 expression level correlated with serum levels of CRP, ferritin, IL-1β, and IL-18. Stimulation of monocytes with LPS results in PLAC8 upregulation. LPS or nigericin stimulation of PLAC8-overexpressing human monocytic cell line (THP-1), but not mock THP-1 cells, was associated with a significant decrease in IL-1β and IL-18 production. PLAC8 overexpression in THP-1 cells was associated with enhanced autophagy and suppression of IL-1β and IL-18 production. Therefore, we found that PLAC8 was upregulated in activated monocytes, as was IL-1β and IL-18. The upregulated PLAC8 acts on the synthesis of inactive precursors of IL-1β and IL-18 and seemed to suppress the production of IL-1β and IL-18 by negative feedback through enhanced autophagy, resulting in the suppression of ASD. The results highlight the role of PLAC8 in the pathogenesis of ASD and suggest its potential suitability as an activity marker and therapeutic target in ASD.

Anakinra for the treatment of adult-onset Still's disease

INTRODUCTION

Adult onset Still's disease (AOSD) is an uncommon systemic inflammatory disease on the clinical spectrum of autoinflammatory disorders. Its presentation and clinical course may result in several well-differentiated phenotypes: from a systemic and highly symptomatic pattern to a chronic articular pattern. Overproduction of numerous pro-inflammatory cytokines is observed in AOSD. Anakinra (ANK), a human interleukin (IL)-1R antagonist, has recently been approved in the EU for the treatment of AOSD. Areas covered: In this review, we discuss the main studies on the efficacy and safety on ANK for the treatment of AOSD. The vast majority of them are retrospective studies and case series. Expert commentary: Overall, ANK is an effective biologic agent for the treatment of AOSD, especially for the systemic pattern and also for those patients who have life-threatening complications, which frequently occur over the course of the disease. The initial dose usually indicated of ANK in adults is 100 mg/day subcutaneously, although dose reduction can be performed in some cases once the disease is under control. The safety profile of ANK is favorable and similar to that described in other rheumatic diseases. In conclusion, ANK is an effective and safe agent for the treatment of AOSD.

Calprotectin in rheumatic diseases: a review

Calprotectin also known as MRP8/14 or S100A8/A9 is a heterodimeric complex of two S100 calcium-binding proteins: myeloid-related protein 8 (MRP-8 or S100A8) and MRP-14 (or S100A9). At present, according to many authors, it is considered that calprotectin MRP8/14 is a potentially more sensitive biomarker of disease activity in rheumatoid disease than conventional inflammatory indices such as the erythrocyte sedimentation rate, C-reactive protein and others. A review of the literature on concentration of calprotectin in patients with some rheumatic diseases (rheumatoid arthritis, juvenile idiopathic arthritis, adult-onset Still's disease, systemic vasculitis, polymyalgia rheumatica, ankylosis spondylitis, systemic lupus erythematosus, and primary Sjögren's syndrome) is presented.

Calprotectin in rheumatic diseases

Calprotectin is a heterodimer formed by two proteins, S100A8 and S100A9, which are mainly produced by activated monocytes and neutrophils in the circulation and in inflamed tissues. The implication of calprotectin in the inflammatory process has already been demonstrated, but its role in the pathogenesis, diagnosis, and monitoring of rheumatic diseases has gained great attention in recent years. Calprotectin, being stable at room temperature, is a candidate biomarker for the follow-up of disease activity in many autoimmune disorders, where it can predict response to treatment or disease relapse. There is evidence that a number of immunomodulators, including TNF-α inhibitors, may reduce calprotectin expression. S100A8 and S100A9 have a potential role as a target of treatment in murine models of autoimmune disorders, since the direct or indirect blockade of these proteins results in amelioration of the disease process. In this review, we will go over the biologic functions of calprotectin which might be involved in the etiology of rheumatic disorders. We will also report evidence of its potential use as a disease biomarker. Impact statement Calprotectin is an acute-phase protein produced by monocytes and neutrophils in the circulation and inflamed tissues. Calprotectin seems to be more sensitive than CRP, being able to detect minimal residual inflammation and is a candidate biomarker in inflammatory diseases. High serum levels are associated with some severe manifestations of rheumatic diseases, such as glomerulonephritis and lung fibrosis. Calprotectin levels in other fluids, such as saliva and synovial fluid, might be helpful in the diagnosis of rheumatic diseases. Of interest is also the potential role of calprotectin as a target of treatment.