Serum amyloid A as a marker of persistent inflammation and an indicator of cardiovascular and renal involvement in patients with rheumatoid arthritis

Race-specific associations: inflammatory mediators and chronic low back pain

ABSTRACT

Chronic low back pain (cLBP) is a global health crisis that disproportionately burdens non-Hispanic Black (NHB) individuals, compared with those who identify as non-Hispanic White (NHW). Despite the growing personal and societal impact of cLBP, its biological underpinnings remain poorly understood. To elucidate the biological factors that underlie the racial disparities in cLBP, this study sought to determine whether inflammatory mediators associated with pain interference (PI), pain at rest (PAR), and movement-evoked pain (MEP) differ as a function of racial identity. Blood samples were collected from 156 individuals with cLBP (n = 98 NHB participants, n = 58 NHW participants). Enzyme-linked immunosorbent assay and multiplex assays were used to quantify concentrations of proinflammatory (fibrinogen, C-reactive protein [CRP], serum amyloid A, tumor necrosis factor α [TNF-α], and interleukin [IL]-1α, IL-1β, and IL-6) and anti-inflammatory markers (IL-4 and IL-13). Spearman rho correlations were used to assess associations among markers of inflammation and PI, PAR, and MEP using the Brief Pain Inventory-Short Form. Analyses revealed that for NHW patients, CRP, serum amyloid A, and IL-6 were positively associated with cLBP outcomes and IL-4 was inversely associated with PAR and MEP. However, for NHB patients, only IL-1α was positively associated with PAR. Our findings suggest that, while there are associations between inflammation and cLBP outcomes, the biomarkers that underlie the inflammation could very well differ as a function of racialized minority group. However, more research with racially inclusive samples is needed to elucidate the mechanisms that may contribute to racial disparities in cLBP.

Artificial intelligence-based preventive, personalized and precision medicine for cardiovascular disease/stroke risk assessment in rheumatoid arthritis patients: a narrative review

The challenges associated with diagnosing and treating cardiovascular disease (CVD)/Stroke in Rheumatoid arthritis (RA) arise from the delayed onset of symptoms. Existing clinical risk scores are inadequate in predicting cardiac events, and conventional risk factors alone do not accurately classify many individuals at risk. Several CVD biomarkers consider the multiple pathways involved in the development of atherosclerosis, which is the primary cause of CVD/Stroke in RA. To enhance the accuracy of CVD/Stroke risk assessment in the RA framework, a proposed approach involves combining genomic-based biomarkers (GBBM) derived from plasma and/or serum samples with innovative non-invasive radiomic-based biomarkers (RBBM), such as measurements of synovial fluid, plaque area, and plaque burden. This review presents two hypotheses: (i) RBBM and GBBM biomarkers exhibit a significant correlation and can precisely detect the severity of CVD/Stroke in RA patients. (ii) Artificial Intelligence (AI)-based preventive, precision, and personalized (aiP3) CVD/Stroke risk AtheroEdge™ model (AtheroPoint™, CA, USA) that utilizes deep learning (DL) to accurately classify the risk of CVD/stroke in RA framework. The authors conducted a comprehensive search using the PRISMA technique, identifying 153 studies that assessed the features/biomarkers of RBBM and GBBM for CVD/Stroke. The study demonstrates how DL models can be integrated into the AtheroEdge™-aiP3 framework to determine the risk of CVD/Stroke in RA patients. The findings of this review suggest that the combination of RBBM with GBBM introduces a new dimension to the assessment of CVD/Stroke risk in the RA framework. Synovial fluid levels that are higher than normal lead to an increase in the plaque burden. Additionally, the review provides recommendations for novel, unbiased, and pruned DL algorithms that can predict CVD/Stroke risk within a RA framework that is preventive, precise, and personalized.

Inflammatory markers in rheumatic diseases

Immune-mediated rheumatic diseases (IMRDs) are a broad group of pathological conditions based on impaired immunological tolerance to one’s own tissues leading to inflammation and irreversible organ damage. Laboratory diagnosis of IMRDs includes a wide range of biomarkers (autoantibodies, acute phase proteins, cytokines, markers of endothelial damage, components of the complement system, immunoglobulins, cryoglobulins, lymphocyte subpopulations, indicators of bone metabolism, apoptosis markers, genetic markers, etc). One of the leading aspects of laboratory diagnosis of IMRDs is the study of the level of inflammation markers in the blood (erythrocyte sedimentation rate, C-reactive protein (CRP), serum amyloid protein (CAA), ferritin, procalcitonin, apolipoprotein AI, calprotectin, etc). The analysis of inflammation markers makes it possible to assess the disease activity, the nature of the progression and the prognosis of the outcomes of a chronic inflammatory process, as well as the effectiveness of the therapy. The review presents the latest data on the role of the most frequently studied inflammatory markers such as CRP, CAA and ferritin.

Human Serum Amyloid a Impaired Structural Stability of High-Density Lipoproteins (HDL) and Apolipoprotein (Apo) A-I and Exacerbated Glycation Susceptibility of ApoA-I and HDL

Human serum amyloid A (SAA) is an exchangeable apolipoprotein (apo) in high-density lipoprotein (HDL) that influences HDL quality and functionality, particularly in the acute phase of inflammation. On the other hand, the structural and functional correlations of HDL containing SAA and apoA-I have not been reported. The current study was designed to compare the change in HDL quality with increasing SAA content in the lipid-free and lipid-bound states in reconstituted HDL (rHDL). The expressed recombinant human SAA1 (13 kDa) was purified to at least 98% and characterized in the lipid-free and lipid-bound states with apoA-I. The dimyristoyl phosphatidylcholine (DMPC) binding ability of apoA-I was impaired severely by the addition of SAA, while SAA alone could not bind with DMPC. The recombinant human SAA1 was incorporated into the rHDL (molar ratio 95:5:1, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC): cholesterol: apoA-I) with various apoA-I:SAA molar ratios from 1:0 to 1:0.5, 1:1 and 1:2. With increasing SAA1 content, the rHDL particle size was reduced from 98 Å to 93 Å, and the α-helicity of apoA-I:SAA was decreased from 73% to 40% for (1:0) and (1:2), respectively. The wavelength maximum fluorescence (WMF) of tryptophan in rHDL was red-shifted from 339 nm to 345 nm for (1:0) and (1:2) of apoA-I:SAA, respectively, indicating that the addition of SAA to rHDL destabilized the secondary structure of apoA-I. Upon denaturation by urea treatment from 0 M to 8 M, SAA showed only a 3 nm red-shift in WMF, while apoA-I showed a 16 nm red-shift in WMF, indicating that SAA is resistant to denaturation and apoA-I had higher conformational flexibility than SAA. The glycation reaction of apoA-I in the presence of fructose was accelerated up to 1.8-fold by adding SAA in a dose-dependent manner than that of apoA-I alone. In conclusion, the incorporation of SAA in rHDL impaired the structural stability of apoA-I and exacerbated glycation of HDL and apoA-I.

Local Insulin-Derived Amyloidosis Model Confronted with Silymarin: Histological Insights and Gene Expression of MMP, TNF-α, and IL-6

Amyloidosis is a heterogeneous group of protein deposition diseases associated with the presence of amyloid fibrils in tissues. Analogs of insulin that are used for treating diabetic patients (including regular insulin) can form amyloid fibrils, both in vitro and in vivo as reported in patients. The main purpose of this study was the induction of localized insulin-generated amyloidosis and the observation of silymarin effects on this process. In order to obtain amyloid structures, regular insulin was incubated at 37 °C for 24 h. Congo red absorbance and transmission electron microscopy images validated the formation of amyloid fibrils. Those fibrils were then injected subcutaneously into rats once per day for 6, 12 or 18 consecutive days in the presence or absence of silymarin, and caused development of firm waxy masses. These masses were excised and stained with Hematoxylin and Eosin, Congo red and Thioflavin S. Histological examination showed adipose cells and connective tissue in which amyloid deposition was visible. Amyloids decreased in the presence of silymarin, and the same effect was observed when silymarin was added to normal insulin and injected subsequently. Furthermore, plasma concentrations of MMP2, TNF-α, and IL-6 inflammatory factors were measured, and their gene expression was locally assessed in the masses by immunohistochemistry. All three factors increased in the amyloidosis state, while silymarin had an attenuating effect on their plasma levels and gene expression. In conclusion, we believe that silymarin could be effective in counteracting insulin-generated local amyloidosis.

Adaptation of Microarray Assay for Serum Amyloid a Analysis in Human Serum

Serum amyloid A is an inflammatory biomarker whose concentration changes during infectious and inflammatory diseases. SAA’s tendency for aggregation and complex formation makes it difficult to determine its concentration in samples, especially when there is an increased level of it. Immunofluorescence SAA determination on a microarray was adapted for SAA quantification in human serum. Both the procedure and the diluent for the calibrator samples were chosen to obtain a dynamic range between 1 and 100 μg/mL. Mixtures of animal (rabbit, goat, mouse) sera with recombinant antigen diluted in certain concentrations were used for the calibrator samples. The method was tested using serum samples from 15 patients with rheumatoid arthritis or ankylosing spondylitis and 9 healthy donors. The results obtained on the microarray demonstrated a good correlation with the results determined by ELISA (Pearson’s correlation coefficient is 0.93). The method developed could be a convenient tool for assessing SAA levels in a number of diseases, such as rheumatoid arthritis or infections of various etiologies, characterized by a significant increase in the level of this protein in the blood. The use of a microarray for the analysis allows the determination of the SAA concentration simultaneously with other inflammatory biomarkers.

Relationship of Troponin I with Neutrophil Lymphocyte Ratio and Serum Amyloid A in Acute Coronary Syndrome

Abstract Introduction: Acute coronary syndrome (ACS) is the leading cause of death in the world. Acute myocardial infarction can initiate an acute inflammatory process by inducing pro-inflammatory cytokines at the cellular level measured by NLR, at the biomolecular level characterized by SAA production in liver. The relationship of elevated troponin I levels as a marker of myocardial necrosis with NLR and SAA as inflammatory markers need further discussion. The purpose of this study was to determine the relationship between cardiac necrosis markers and inflammatory parameters in ACS. Methods: An analytic observational study with a cross-sectional approach was conducted from March to May 2019. This study involved 32 patients with ACS at the Emergency Department of Dr.Kariadi Hospital, with the onset of attacks of 4-6 hours which met the inclusion and exclusion criteria. Examination of troponin I level was done using the ELFA method, NLR value was measured using a hematology analyzer, and SAA level was measured using the ELISA method. Statistical test was done using Spearman correlation. Value of p < 0.05 was considered significant. Results: The median (min-max) of troponin I, NLR, and SAA values were 0.617 (0.001-40,000) μg/L, 4.92 (1.38-18.16) and 40.454 (5.879-66.059) μg/ml, respectively. The correlation of troponin I level with NLR and SAA were r=0.180, p=0.243 and r=0.655, p=0.000. Conclusions: There was a significant positive moderate relationship between troponin I level and SAA which could be used as a marker of acute inflammation in ACS, whereas cell inflammation marker of NLR did not provide a significant meaning. Keywords: ACS, NLR, SAA, troponin

Role of Polypeptide Inflammatory Biomarkers in the Diagnosis and Monitoring of COVID-19

The COVID-19 (coronavirus disease 2019) pandemic that took over the world in December 2019 has had everlasting devastating impacts on the lives of people globally. It manifests a huge symptom spectrum ranging from asymptomatic to critically ill patients with an unpredictable outcome. Timely diagnosis and assessment of disease severity is imperative for effective treatment. Possibilities exist that by the time symptoms appear the viral load might increase beyond control. However, it is advisable to get adequately diagnosed as soon as the first symptom appears. There is an immediate requirement of reliable biomarkers of COVID-19 manifesting an early onset for effective clinical management, stratification of high risk patients and ensuring ideal resource allocation. In this review, we attempt to explore and describe important polypeptide inflammatory biomarkers, namely C-reactive protein, Procalcitonin, Ferritin, Lactate Dehydrogenase, Serum amyloid A, Interleukin-6, Tumor necrosis factor-alpha and LIGHT used in the detection and management of COVID-19. Viral pathogenesis and the role of these inflammatory biomarkers is highlighted, based on the evidences available till date. An integrative data monitoring along with their correlation with the natural disease progression is of utmost importance in the management of COVID-19. So further research and in-depth analysis of these biomarkers is warranted in the present scenario.

Analysis of rheumatoid factor and acute phase proteins using microarrays in patients with rheumatoid arthritis

One of the biomarkers of biggest clinical importance in rheumatoid arthritis (RA) is rheumatoid factor (IgM RF). The rheumatoid factor has insufficient sensitivity and specificity, therefore, to increase the diagnostic information of the test, acute phase proteins were used as concomitant biomarkers. Using biological microchips, we measured IgM RF, C-reactive protein (CRP) and Serum amyloid protein A (SAA) in patients with RA (n = 60), ankylosing spondylitis (AS) (n=55), systemic lupus erythematosus (SLE) (n=20) and healthy donors (HD) (n=9). It was shown that the medians of IgM RF concentrations are significantly higher (p<0.01) in patients with RA compared to patients suffering from other diseases and healthy donors. CRP and SAA were also significantly increased (p<0.05) in patients with RA and AS compared with SLE and HD. It has been shown that the complex determination of three biomarkers in differentiating RA patients with the comparison group had a higher diagnostic sensitivity than the isolated determination of IgM RF, while the addition of SAA makes the greatest contribution to improving the diagnostic characteristics of the biomarker panel: the use of a logistic regression model based on IgM RF and SAA allowed to increase the diagnostic sensitivity of the analysis from 58.3% to 65%. Thus, the developed microarray-based method can be used to detect and elucidate the diagnostic characteristics of RA biomarkers; however, further use requires validation of the obtained results on an expanded sampling.

Potential Immune Indicators for Predicting the Prognosis of COVID-19 and Trauma: Similarities and Disparities

Although cellular and molecular mediators of the immune system have the potential to be prognostic indicators of disease outcomes, temporal interference between diseases might affect the immune mediators, and make them difficult to predict disease complications. Today one of the most important challenges is predicting the prognosis of COVID-19 in the context of other inflammatory diseases such as traumatic injuries. Many diseases with inflammatory properties are usually polyphasic and the kinetics of inflammatory mediators in various inflammatory diseases might be different. To find the most appropriate evaluation time of immune mediators to accurately predict COVID-19 prognosis in the trauma environment, researchers must investigate and compare cellular and molecular alterations based on their kinetics after the start of COVID-19 symptoms and traumatic injuries. The current review aimed to investigate the similarities and differences of common inflammatory mediators (C-reactive protein, procalcitonin, ferritin, and serum amyloid A), cytokine/chemokine levels (IFNs, IL-1, IL-6, TNF-α, IL-10, and IL-4), and immune cell subtypes (neutrophil, monocyte, Th1, Th2, Th17, Treg and CTL) based on the kinetics between patients with COVID-19 and trauma. The mediators may help us to accurately predict the severity of COVID-19 complications and follow up subsequent clinical interventions. These findings could potentially help in a better understanding of COVID-19 and trauma pathogenesis.

Association between serum amyloid A and rheumatoid arthritis: A systematic review and meta-analysis

BACKGROUNDS

Consistent correlation of serum amyloid A (SAA) to rheumatoid arthritis (RA) is not completely established. The present study is to systematically summarize their relationship.

METHODS

Publications up to may 2021 were examined using key terms in the PubMed, Cochrane Library, Embase and China national knowledge infrastructure (CNKI) databases.

RESULTS

The total 33 studies, involving in 3524 RA cases and 3537 normal participants, were included. The pooled result indicated that the SAA level in the RA group was markedly higher than that in the control group [standardized mean difference (SMD) = 0.80, 95% CI (0.51, 1.08)]. By stratified analyses, the concentration of SAA was found to be gradually increased with the aggravation of RA. Additionally, the meta-analysis of correlation demonstrated that SAA levels were positively associated with the levels of disease activity score 28 (DAS28) [r = 0.55, 95% CI (0.15, 0.94)], erythrocyte sedimentation rate (ESR) [r = 0.65, 95% CI (0.53, 0.76)], C-reactive protein (CRP) [r = 0.92, 95% CI (0.57, 1.57)], rheumatoid factor (RF) [r = 0.24, 95% CI (0.09, 0.39)], interleukin 4 (IL-4) [r = 0.54, 95% CI (0.30, 0.78)], interleukin 6 (IL-6) [r = 0.46, 95% CI (0.27, 0.65)], interleukin 10 (IL-10) [r = 0.53, 95% CI (0.29, 0.77)], interleukin 17 (IL-17) [r = 0.52, 95% CI (0.27, 0.77)], and anti-cyclic citrullinated peptide antibody (A-CCP) [r = 0.32, 95% CI (0.15, 0.50)], but inversely linked with the levels of hemoglobin [r=-0.51, 95% CI (-0.84, -0.18)]. Furthermore, the allele of SAA 1.3 was actively related with increased risks of RA [OR=1.30, 95% CI (1.02, 1.65)] and of RA with amyloidosis [OR=2.06, 95% CI (1.63, 2.60)]. Besides, the genotype of SAA 1.3/1.3 was positively connected with the risks of RA [OR=1.56, 95% CI (1.00, 2.43)] and of RA with amyloidosis [OR=4.47, 95% CI (2.70, 7.41)].

CONCLUSIONS

High levels of SAA might be associated with elevated risk of RA, and the concentration of SAA might be gradually increased with the aggravation of RA. Moreover, high levels of SAA might play a vital role in RA by enhancing the levels of DAS28, ESR, CRP, RF, IL-4, IL-6, IL-10, IL-17 and A-CCP, or by attenuating hemoglobin levels. More importantly, the allele of SAA 1.3 and genotype of SAA 1.3/1.3 might be the risk factor of RA and of RA with amyloidosis.

Discrepancy Between SAA and CRP levels Linked to the Difference of SAA/CRP ratio in Early Rheumatoid Arthritis

OBJECTIVES

Indeed, serum amyloid A (SAA) and C-reactive protein (CRP) reportedly seem to have moderate correlation, but discrepancies between CRP and SAA levels have often been reported in patients with early rheumatoid arthritis (ERA). This study aimed to determine the reasons for this discrepancy.

METHODS

ERA patients (n = 206) were enrolled and treated with anti-RA drugs. Clinical features and disease activities were estimated. CRP and SAA levels were monitored, and the SAA/CRP ratio was compared. Correlations between CRP and SAA levels in individuals and between individuals, and disease activity scores were examined.

RESULTS

In a follow-up study, the SAA/CRP ratio remained almost constant over time in the same patients. However, SAA/CRP ratios differed widely between patients (0.233-106.3). In patients with high SAA/CRP ratio (>6.52), many (26.2%) had abnormal SAA values only. In patients with low SAA/CRP ratio (<6.52), not a few (6.8%) exhibited abnormal CRP values only.

CONCLUSIONS

The SAA/CRP ratio remained virtually constant in the same patients but differed dramatically between patients, which clarifies the discrepancy between CRP and SAA levels. CRP is the better marker in low-ratio patients, but not in high-ratio patients; the SAA/CRP ratio is critical for its interpretation.

Investigation of Specific Proteins Related to Different Types of Coronary Atherosclerosis

Objective: Coronary heart disease (CHD) is a complex disease caused by multifaceted interaction between genetic and environmental factors, which makes identification of the most likely disease candidate proteins and their associated risk markers a big challenge. Atherosclerosis is presented by a broad spectrum of heart diseases, including stable coronary artery disease (SCAD) and acute myocardial infarction (AMI), which is the progressive stage of SCAD. As such, the correct and prompt diagnosis of atherosclerosis turns into imperative for precise and prompt disease diagnosis, treatment and prognosis. Methods: The current work aims to look for specific protein markers for differential diagnosis of coronary atherosclerosis. Thirty male patients between 45 and 55 years diagnosed with atherosclerosis were analyzed by tandem mass tag (TMT) mass spectrometry. The study excluded those who were additionally diagnosed with hypertension and type 1 and 2 diabetes. The Mufuzz analysis was applied to select target proteins for precise and prompt diagnosis of atherosclerosis, most of which were most related to high lipid metabolism. The parallel reaction monitoring (PRM) was used to verify the selected target proteins. Finally, The receiver operating characteristic curve (ROC) was calculated by a random forest experiment. Results: One thousand one hundred and forty seven proteins were identified in the TMT mass spectrometry, 907 of which were quantifiable. In the PRM study, six proteins related to lipid metabolism pathway were selected for verification and they were ALB, SHBG, APOC2, APOC3, APOC4, SAA4. Conclusion: Through the detected specific changes in these six proteins, our results provide accuracy in atherosclerosis patients' diagnosis, especially in cases with varying types of the disease.

Prospective selected biomarkers in COVID-19 diagnosis and treatment

COVID-19 has become a global health concern, due to the high transmissible nature of its causal agent and lack of proper treatment. Early diagnosis and nonspecific medical supports of the patients appeared to be effective strategy so far to combat the pandemic caused by COVID-19 outbreak. Biomarkers can play pivotal roles in timely and proper diagnosis of COVID-19 patients, as well as for distinguishing them from other pulmonary infections. Besides, biomarkers can help in reducing the rate of mortality and evaluating viral pathogenesis with disease prognosis. This article intends to provide a broader overview of the roles and uses of different biomarkers in the early diagnosis of COVID-19, as well as in the classification of COVID-19 patients into multiple risk groups.

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.

Characterization of Human Genes Modulated by Porphyromonas gingivalis Highlights the Ribosome, Hypothalamus, and Cholinergic Neurons

Porphyromonas gingivalis, a bacterium associated with periodontal disease, is a suspected cause of Alzheimer's disease. This bacterium is reliant on gingipain proteases, which cleave host proteins after arginine and lysine residues. To characterize gingipain susceptibility, we performed enrichment analyses of arginine and lysine proportion proteome-wide. Genes differentially expressed in brain samples with detected P. gingivalis reads were also examined. Genes from these analyses were tested for functional enrichment and specific neuroanatomical expression patterns. Proteins in the SRP-dependent cotranslational protein targeting to membrane pathway were enriched for these residues and previously associated with periodontal and Alzheimer's disease. These ribosomal genes are up-regulated in prefrontal cortex samples with detected P. gingivalis sequences. Other differentially expressed genes have been previously associated with dementia (ITM2B, MAPT, ZNF267, and DHX37). For an anatomical perspective, we characterized the expression of the P. gingivalis associated genes in the mouse and human brain. This analysis highlighted the hypothalamus, cholinergic neurons, and the basal forebrain. Our results suggest markers of neural P. gingivalis infection and link the cholinergic and gingipain hypotheses of Alzheimer's disease.

The Correlation between Serum Amyloid A, Mean Platelet Volume, and Creatine Kinase Myocardial B in Acute Coronary Syndrome

BACKGROUND: Atherosclerosis causes acute myocardial necrosis and inflammation characterized by increased mean platelet volume (MPV) and serum amyloid A (SAA). Creatine Kinase Myocardial Band (CKMB) is known as myocardial necrosis marker commonly used in daily practice to help diagnosing acute coronary syndrome. AIM: The purpose of this study was to determine the correlation between MPV, SAA, and CKMB in patients with acute coronary syndrome. METHODS: An analytic observational study with a cross-sectional approach was conducted from May to July 2019. This study involved 32 patients with ACS at the Emergency Department of Dr Kariadi Public Hospital. The inclusion criteria of this study were patients with chest pain, aged 30–75 years, and normal body temperature while the exclusion criteria were malignancy, undergoing chemotherapy/radiation, renal failure, hypertension, and liver disease. Examination of CKMB was done using the spectrophotometry method, MPV value was measured using a hematology analyzer, and SAA level was measured using the ELISA method. Statistical test was done using Spearman correlation. RESULTS: The median (min-max) of MPV and SAA values was 9.85 (2.78-11.7) fL and 40.454 (5.879–66.059) μg/ml, while the mean ± SD (min-max) value of CKMB was 115.47 ± 155.97 (10–608) U/L. The correlation coefficient between CKMB level with MPV and SAA levels were r = −0.244 (p = 0.179) and r = 0.442 (p = 0.011), respectively. CONCLUSION: There was a significant positive moderate correlation between CKMB and SAA levels which could be used as a marker of acute inflammation in ACS, whereas inflammatory marker of MPV did not have a significant correlation.

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.

Serum biomarker panel for the diagnosis of rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is an autoimmune disease of inflammatory joint damage, wherein C-reactive protein and autoantibodies including rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) are rapidly elevated. These serological factors are diagnostic markers of RA; however, their sensitivity and specificity for prediction warrant improvement for an early and accurate diagnosis.

Methods

We aimed to identify alternative biomarkers by serum protein profiling using LC-MS/MS. We performed statistical and functional analysis of differentially expressed proteins to identify biomarker candidates complementing conventional serological tests.

Results

Seven biomarker candidates were verified through multiple reaction monitoring-based quantitative analysis, of which angiotensinogen (AGT), serum amyloid A-4 protein (SAA4), vitamin D-binding protein (VDBP), and retinol-binding protein-4 (RBP4) had an area under the curve over 0.8, thus distinguishing RA patients, including seronegative (RF- and anti-CCP-negative) RA patients, from healthy controls.

Conclusions

Therefore, among seronegative RA patients, a four-biomarker panel (AGT, SAA4, VDBP, and RBP4) can prevent false negatives and help diagnose RA accurately.

Utility of a Simple Scoring System in Differentiating Bacterial Infections in Cases of Fever of Unknown Origin

BACKGROUND

Infectious disease is the leading cause of fever of unknown origin (FUO). Serum inflammatory markers historically used to diagnose bacterial infection have sufficient diagnostic sensitivity but low specificity. This study aimed to develop a simple scoring system for differentiating bacterial infections from other causes of early-stage FUO.

METHODS

This study included a retrospective cohort of patients presenting with FUO at the Huashan Hospital (January 2014 to June 2017). The diagnostic utility of serum inflammatory markers for bacterial infection was evaluated using the receiver operating characteristic (ROC) curve analysis. Relevant markers were subsequently measured prospectively in a separate cohort of FUO patients (December 2017 to May 2019). A scoring system was based on inflammatory markers and other test results.

RESULTS

Bacterial infection was identified in 34% of patients in the retrospective cohort. The area under the ROC curve (AUC) was 0.644 (95% confidence interval [CI], .595-.693) for C-reactive protein, 0.624 (95% CI, .573-.675) for procalcitonin, and 0.646 (95% CI, .595-.697) for serum ferritin (SF) in diagnosing bacterial infection. Bacterial infection was found in 29% of cases in the prospective cohort. A model based on serum amyloid A (SAA) and SF levels and neutrophil percentage yielded an AUC of 0.775 (95% CI, .695-.854). Validation analysis indicated lower probability (<15%) of bacterial infection for patients with a score <16.5 points.

CONCLUSIONS

A scoring system based on SAA and SF levels and neutrophil percentage can help distinguish bacterial infection from other causes of FUO, potentially reducing antibiotic use.

Proinflammatory mediators and their associations with medication and comorbid traits in children and adults with ADHD

Peripheral immune activation can influence neurodevelopment and is increased in autism, but is less explored in attention deficit hyperactivity disorder (ADHD). Patients with ADHD often display comorbid autism traits and gastrointestinal (GI) symptoms. Plasma protein levels of two acute phase reactants, C-reactive protein (CRP) and serum amyloid A (SAA), and two endothelial adhesion molecules, soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule 1 (sVCAM-1), which share important roles in inflammation, were analyzed in 154 patients with ADHD and 61 healthy controls. Their associations with ADHD diagnosis, severity, medication and comorbid autistic symptoms, emotion dysregulation and GI symptoms were explored. The ADHD patients had increased levels of sICAM-1 and sVCAM-1 compared to healthy controls (p = 8.6e-05, p = 6.9e-07, respectively). In children with ADHD, the sICAM-1 and sVCAM-1 levels were higher among those with ADHD medication than among children (p = 0.0037, p = 0.0053, respectively) and adults (p = 3.5e-09, p = 1.9e-09, respectively) without ADHD medication. Among the adult ADHD patients, higher sICAM-1 levels were associated with increased comorbid autistic symptoms in the domains attention to detail and imagination (p = 0.0081, p = 0.00028, respectively), and higher CRP levels were associated with more GI symptoms (p = 0.014). sICAM-1 and sVCAM-1 levels were highly correlated with each other, and so were CRP and SAA levels. To conclude, vascular inflammatory activity may be overrepresented in ADHD, with elevated sICAM-1 and sVCAM-1 levels and this may in children be a consequence of current ADHD medication, and in adults relate to increased comorbid autistic symptoms. Replication is warranted.

Evaluation of inflammatory biomarkers in goats naturally infected with Babesia ovis

This study was designed to evaluate the effects of Babesia ovis infection on concentrations of some essential acute phase proteins (APPs) including albumin, fibrinogen, serum amyloid A, haptoglobin, and ceruloplasmin as well as total, protein-binding, and lipid-binding sialic acids (TSA, PBSA, and LBSA) and two crucial cytokines including interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α). Some hematological parameters also were evaluated. Furthermore, any probable correlation among the APPs, SAs, IFN-γ, and TNF-α was calculated. A total of 420 Marghoz and Raeini goats with the ages of 1-3 years old from the north and northwest of Iran were examined, and 17 goats confirmed to be infected with B. ovis by both routine microscopic examination of blood films and molecular assays. As the control, 17 healthy goats were included. The results revealed a significant decrease (P < 0.05) in erythrocyte count, hemoglobin level, and pack cell volume as well as a nonsignificant increase in white blood cell count in the diseased animals compared with the control. Additionally, all the APPs, SAs, and cytokines were remarkably higher in the infected animals than the uninfected ones, except for albumin, which was significantly lower. Moreover, a strong and positive correlation was detected among the parameters mentioned above, except for albumin, which was inversely correlated with the other parameters. In conclusion, B. ovis infection is associated with the induction of severe inflammatory reactions in goats, and both SA and APP are significantly involved in the pathophysiology of the disease.

Sex as a Determinant of Responses to a Coronary Artery Disease Self-Antigen Identified by Immune-Peptidomics

A significant body of work implicates the adaptive immune response in atherosclerosis, the main underlying cause of coronary artery disease (CAD), yet specific antigens involved remain to be fully identified. The pathobiology of CAD is influenced by sex with many factors that may be involved in the underlying mechanisms. Given the reported sexual dimorphic nature of immune-inflammatory responses, we investigated the influence of sex on potential CAD self-antigens from acute coronary syndrome (ACS) patients using immune-precipitation of soluble HLA Class-I/peptide complexes and mass spectrometry. Relevance of identified self-antigens to atherosclerosis, the major underlying cause of CAD, was tested in the apoE–/– atherosclerotic mouse model. Soluble HLA Class-I complexes from ACS patients and self-reported controls were immune-precipitated and subjected to elution, denaturation and size-exclusion to obtain HLA-bound peptides. Peptides were then subjected to mass spectrometry and patient-unique self-peptides were grouped as common to both female and male, or unique to either sex. Three peptides common to both female and male patients (COL6A1, CDSN, and SAA2), and 2 peptides each unique to female (COL1A1 and COL5A2) or male (SAA1 and KRT 9) patients were selected and mouse homologs of the peptides were screened for self-reactive immune responses in apoE–/– mice. The screening step revealed potential sex-influenced immune responses which was associated with differential immune profiles. Based on the frequency in patient plasma, COL6A1, COL5A2, and KRT 9 peptides were then tested in immunization studies. Neither COL5A2 nor KRT 9 peptide immunization resulted in significant effects on atherosclerosis compared to controls. On the other hand, female mice immunized with COL6A1 peptide had significantly reduced atherosclerosis whereas male mice had significantly increased atherosclerosis, associated with differential immune profiles. Our study identified potential self-antigens involved in atherosclerosis using the immune peptidome of CAD patients. Altering self-reactive immune responses to COL6A1 in apoE–/– mice resulted in differential effects on atherosclerosis burden with sex as a determinant of outcome.

Incomplete ART adherence is associated with higher inflammation in individuals who achieved virologic suppression in the START study

Introduction

Suboptimal ART adherence, despite HIV viral suppression, has been associated with chronic residual inflammation. Whether this association extends to individuals who initiate ART during early HIV infection remains unknown, which was the objective of this study.

Methods

Plasma levels of interleukin‐6 (IL‐6), high‐sensitivity C‐reactive protein, serum amyloid A protein (SAA), IL‐27, soluble intercellular adhesion molecule‐1, soluble vascular adhesion molecule‐1, D‐dimer and the CD4+/CD8+ T‐cell ratio, were analysed at baseline and eight months after ART initiation in treatment‐naïve participants with HIV and CD4+ T‐cells >500 cells/mm³ enrolled in the immediate arm of START. Adherence was assessed by seven‐day self‐report. Multivariable linear regression was utilized to analyse the association between ART adherence and each biomarker at the eight‐month visit in participants who achieved virologic suppression (<50 copies/mL).

Results

We evaluated 1627 participants (422 female) who achieved virologic suppression at the eight‐month visit in the period between 2009 and 2013. Median (IQR) CD4+ T‐cell count before ART was 651 (585, 769) cells/mm³. Incomplete adherence was reported in 109 (7%) participants at the eight month visit. After adjusting for covariates, plasma IL‐6 was 1.12 (95% CI, 1.00 to 1.26; p = 0.047) fold higher in participants reporting incomplete versus 100% adherence. A similar association for SAA was observed in an exploratory analysis (1.29 (95% CI 1.04 to 1.60); p = 0.02). No significant differences in other biomarkers were observed.

Conclusions

Incomplete ART adherence was associated with higher IL‐6 levels in individuals who achieved virologic suppression early after ART initiation in START. A potential similar association for SAA requires confirmation. These findings suggest a role for identifying strategies to maximize ART adherence even during virologic suppression. ClinicalTrials.gov number: NCT00867048.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.

Telmisartan alone or in combination with etanercept improves anemia associated with rheumatoid arthritis in rats: a possible role of anti-inflammatory and reno-protective effects

BACKGROUND

There are conflicting data regarding angiotensin receptor blockers (ARBs) induced anemia and its beneficial anti-inflammatory effect in rheumatoid arthritis. The aim of the present study was to investigate the effect of telmisartan administration either alone or in combination with etanercept on anemia of chronic inflammatory diseases in a model of rheumatoid arthritis in rats.

METHODS

Rheumatoid arthritis (RA) was induced by Freund's Complete Adjuvant (FCA; 1 mg/0.1 ml paraffin oil), injected subcutaneously on days 0, 30 and 40. Rats with RA received dimethyl sulfoxide (DMSO), etanercept (0.3 mg/kg 3 times/week; sc), telmisartan (1.5 mg/kg/day; orally) or combination of etanercept and telmisartan. Arthritis parameters (footpad circumference change and paw volume change), erythrocyte indices (hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin level changes), iron profile (serum iron and serum ferritin), serum levels of erythropoietin (EPO), hepcidin, tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6 were evaluated, along with measuring serum urea and creatinine levels.

RESULTS

All treated groups showed improvement of the measured parameters in comparison to RA-control subgroup. Telmisartan either alone or in combination with etanercept significantly improved arthritis and erythrocyte indices. Telmisartan showed significant increase in EPO and decrease in hepcidin compared to etanercept. Combination group showed significant improvement in serum iron, ferritin, EPO, hepcidin, TNF-α, IL-6, urea and creatinine, compared to etanercept. Telmisartan either alone or in combination, but not etanercept alone, significantly decreased creatinine level.

CONCLUSION

Telmisartan improved anemia and arthritis parameters and showed anti-inflammatory and reno-protective effects, in a rat model of rheumatoid arthritis.

Neutralizing effects of anti-infliximab antibodies on synergistically-stimulated human coronary artery endothelial cells

BACKGROUND AND AIMS

Patients with rheumatic diseases have an increased risk of atherosclerosis with up-regulated serum amyloid A (SAA), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), which were reported to activate human coronary artery endothelial cells (HCAEC). We aimed to investigate the effects of TNF-α inhibitor infliximab and anti-infliximab antibodies on the TNF-α/IL-1β/SAA activated HCAEC.

METHODS

HCAEC were incubated with TNF-α, IL-1β, SAA, infliximab, anti-infliximab antibodies and their combinations. The protein levels of pro- and anti-atherogenic analytes were measured in supernatants using ELISA and multiplex assays, while mRNA expression was determined by RT-PCR. Anti-infliximab antibodies were purified from sera samples by affinity chromatography.

RESULTS

IL-6, IL-8, GM-CSF and GRO-α were synergistically up-regulated in triple stimulation with TNF-α, IL-1β and SAA, while their levels in solely SAA- or TNF-α-stimulated HCAEC did not increase. IL-1Ra, IL-1α, VCAM-1, MCP-1, IL-10 and IL-17A were increased, but no synergistic responses were observed in triple stimulation. Infliximab was effective in lowering the synergistic effect of IL-6, IL-8, GM-CSF and GRO-α in triple stimulation, while anti-infliximab antibodies restored the levels. The changes were confirmed at the mRNA expression level for IL-6, IL-8 and GM-CSF.

CONCLUSIONS

Triple stimulation with TNF-α, IL-1β and SAA synergistically elevated IL-6, IL-8, GM-CSF and GRO-α release in supernatants of HCAEC, with infliximab substantially inhibiting their levels. An isolated, enriched fraction of polyclonal anti-infliximab antibodies was capable of neutralizing infliximab, in the presence of TNF-α/IL-1β/SAA. The long-term presence of anti-infliximab antibodies in the circulation of patients with chronic rheumatic diseases is potentially important for promoting the atherosclerotic process.

Metabolic syndrome is an inflammatory disorder: A conspiracy between adipose tissue and phagocytes

Metabolic syndrome (MetS) describes a cluster of cardio-metabolic factors that predispose to type 2 diabetes mellitus (T2DM) and atherosclerotic cardiovascular disease (ASCVD). While 35% of Americans suffer from this disorder, the specific pathways related to this disease are largely underexplored. The prevailing consensus is that inflammatory pathways contribute to the pathogenesis of this disease, and therefore new research has uncovered how inflammation plays a critical role in the development and progression of MetS. The purpose of this review is to understand the role of major inflammatory mechanisms and their role in MetS. Our review identifies that adipose tissue (AT) contributes to the inflammatory pathways through the release of pro-inflammatory adipokines such as leptin and chemerin and dysregulation of anti-inflammatory adiponectin. Chemokines and cytokines deriving from monocytes are also altered and promote inflammation and insulin resistance. Circulating inflammatory biomarkers including C-reactive protein (CRP), fibrinogen, Serum amyloid A (SAA), cytokines, and chemokines have also been linked to the pathogenesis of MetS. Researchers have identified the significance of CRP levels in predicting future sequelae of MetS such as ASCVD. Mast cells in subcutaneous adipose tissue (SAT) promote both inflammation and fibrosis. Thus, both AT and phagocyte activity define MetS as an inflammatory disorder.

The prognostic value of serum amyloid A for long-term mortality among patients with subclinical carotid atherosclerosis

BACKGROUND AND PURPOSE

Despite extensive research in the last decade, the role of serum amyloid A (SAA) in atherogenesis remains highly controversial. The aim of this study was therefore to assess whether SAA is associated with long-term mortality in patients with subclinical carotid artery disease.

METHODS

One thousand sixty-five patients with neurological asymptomatic carotid atherosclerosis as evaluated by duplex sonography were prospectively followed for cause-specific mortality.

RESULTS

During a median of 11.8 years, a total of 549 deaths, including 362 cardiovascular deaths, were recorded. Patients who died within the follow-up period had significantly higher baseline SAA serum levels compared to those who survived (12.9 vs 9.5 mg/dL; P < 0.001). In univariable Cox regression analysis, the risk of all-cause and cardiovascular mortality significantly increased in patients with elevated serum levels of SAA (crude hazard ratio for cardiovascular mortality per increase of 1 SD of SAA levels was 1.14, 95% CI 1.08-1.22], P < 0.0001). However, SAA lost its significance after adjusting for high-sensitivity C-reactive protein (hsCRP), suggesting that SAA might not be directly associated with atherogenesis, but rather be a mere reflection of the individual patient's inflammatory status.

CONCLUSIONS

Serum amyloid A is not independently associated with (cardiovascular) mortality in patients with subclinical carotid atherosclerosis.

Serum Amyloid A Stimulates Vascular and Renal Dysfunction in Apolipoprotein E-Deficient Mice Fed a Normal Chow Diet

Elevated serum amyloid A (SAA) levels may promote endothelial dysfunction, which is linked to cardiovascular and renal pathologies. We investigated the effect of SAA on vascular and renal function in apolipoprotein E-deficient (ApoE^−/−) mice. Male ApoE^−/− mice received vehicle (control), low-level lipopolysaccharide (LPS), or recombinant human SAA by i.p. injection every third day for 2 weeks. Heart, aorta and kidney were harvested between 3 days and 18 weeks after treatment. SAA administration increased vascular cell adhesion molecule (VCAM)-1 expression and circulating monocyte chemotactic protein (MCP)-1 and decreased aortic cyclic guanosine monophosphate (cGMP), consistent with SAA inhibiting nitric oxide bioactivity. In addition, binding of labeled leukocytes to excised aorta increased as monitored using an ex vivo leukocyte adhesion assay. Renal injury was evident 4 weeks after commencement of SAA treatment, manifesting as increased plasma urea, urinary protein, oxidized lipids, urinary kidney injury molecule (KIM)-1 and multiple cytokines and chemokines in kidney tissue, relative to controls. Phosphorylation of nuclear-factor-kappa-beta (NFκB-p-P65), tissue factor (TF), and macrophage recruitment increased in kidneys from ApoE^−/− mice 4 weeks after SAA treatment, confirming that SAA elicited a pro-inflammatory and pro-thrombotic phenotype. These data indicate that SAA impairs endothelial and renal function in ApoE^−/− mice in the absence of a high-fat diet.

Rheumatoid Arthritis: Atherosclerosis Imaging and Cardiovascular Risk Assessment Using Machine and Deep Learning-Based Tissue Characterization

PURPOSE OF THE REVIEW

Rheumatoid arthritis (RA) is a chronic, autoimmune disease which may result in a higher risk of cardiovascular (CV) events and stroke. Tissue characterization and risk stratification of patients with rheumatoid arthritis are a challenging problem. Risk stratification of RA patients using traditional risk factor-based calculators either underestimates or overestimates the CV risk. Advancements in medical imaging have facilitated early and accurate CV risk stratification compared to conventional cardiovascular risk calculators.

RECENT FINDING

In recent years, a link between carotid atherosclerosis and rheumatoid arthritis has been widely discussed by multiple studies. Imaging the carotid artery using 2-D ultrasound is a noninvasive, economic, and efficient imaging approach that provides an atherosclerotic plaque tissue-specific image. Such images can help to morphologically characterize the plaque type and accurately measure vital phenotypes such as media wall thickness and wall variability. Intelligence-based paradigms such as machine learning- and deep learning-based techniques not only automate the risk characterization process but also provide an accurate CV risk stratification for better management of RA patients. This review provides a brief understanding of the pathogenesis of RA and its association with carotid atherosclerosis imaged using the B-mode ultrasound technique. Lacunas in traditional risk scores and the role of machine learning-based tissue characterization algorithms are discussed and could facilitate cardiovascular risk assessment in RA patients. The key takeaway points from this review are the following: (i) inflammation is a common link between RA and atherosclerotic plaque buildup, (ii) carotid ultrasound is a better choice to characterize the atherosclerotic plaque tissues in RA patients, and (iii) intelligence-based paradigms are useful for accurate tissue characterization and risk stratification of RA patients.

Development of a Novel Diagnostic Biomarker Set for Rheumatoid Arthritis Using a Proteomics Approach

Background

Rheumatoid arthritis (RA) is an autoimmune disease that starts with inflammation of the synovial membrane. Studies have been conducted to develop methods for efficient diagnosis of RA and to identify the mechanisms underlying RA development. Blood samples can be useful for detecting disturbance of homeostasis in patients with RA. Nanoliquid chromatography-tandem mass spectrometry (LC-MS/MS) is an efficient proteomics approach to analyze blood sample and quantify serum proteins.

Methods

Serum samples of 18 healthy controls and 18 patients with RA were analyzed by LC-MS/MS. Selected candidate biomarkers were validated by enzyme-linked immunosorbent assay (ELISA) using sera from 43 healthy controls and 44 patients with RA.

Results

Thirty-eight proteins were significantly differentially expressed by more than 2-fold in healthy controls and patients with RA. Based on a literature survey, we selected six candidate RA biomarkers. ELISA was used to evaluate whether these proteins effectively allow distinguishing patients with RA from healthy controls and monitoring drug efficacy. SAA4, gelsolin, and vitamin D-binding protein were validated as potential biomarkers of RA for screening and drug efficacy monitoring of RA.

Conclusions

We identified a panel of three biomarkers for RA which has potential for application in RA diagnosis and drug efficacy monitoring. Further, our findings will aid in understanding the pathogenesis of RA.

Multiplex Assay for Quantification of Acute Phase Proteins and Immunoglobulin A in Dried Blood Spots

Inflammation is the first line defense mechanism against infection, tissue damage, or cancer development. However, inappropriate inflammatory response may also trigger diseases. The quantification of inflammatory proteins is essential to distinguish between harmful and beneficial immune response. Currently used immunoanalytical assays may suffer specificity issues due to antigen-antibody interaction and possible cross-reactivity of antibody with other protein species. In addition, immunoanalytical assays typically require invasive blood sampling and additional logistics; they are relatively costly and highly challenging to multiplex. We present a multiplex assay based on selected reaction monitoring (SRM) for quantification of seven acute-phase proteins (i.e., SAA1, SAA2-isoform1, SAA4, CRP, A1AT-isoform1, A1AG1, A1AG2) and the adaptive immunity effector IGHA1 in dried blood spots. This type of sample is readily available from all human subjects including newborns. The study utilizes proteotypic isotopically labeled peptides with trypsin-cleavable tag and presents optimized and reproducible workflow and several important practical remarks regarding quantitative SRM assays development. The panel of inflammatory proteins was quantified with sequence specificity capable to differentiate protein isoforms with intra- and interday precision (<16.4% coefficient of variation (CV) and <14.3% CV, respectively). Quantitative results were correlated with immuno-nephelometric assay (typically greater than 0.9 Pearson's R).

What role does rheumatoid arthritis disease activity have in cardiovascular risk?

Rheumatoid arthritis (RA) is associated with a 1.3 to 3-fold increase in mortality, being the major cause of death from cardiovascular complications (40%-50%). Therefore, the initial approach should include cardiovascular risk (CVR) assessment using algorithms adapted for this population. Although, SCOREM is an important advance, there are data indicating that subclinical atherosclerosis may be underdiagnosed.

OBJECTIVE

To estimate the strength of association between carotid ultrasound and SCOREM in this population, as well as the implication of disease activity.

METHODOLOGY

Cross-sectional, observational, analytical study performed at the General Hospital of Ciudad Real, Spain, between June 2013 and May 2014. The evaluation of CVR was performed and, according to SCOREM, the population was divided into low and high (medium, high and very high) risk. We studied the presence of subclinical atherosclerosis in low-risk patients.

RESULTS

Of the total of 119 RA patients, 73.1% had traditional risk factors. Thirty-eight patients were excluded because of a previous cardiovascular event, diabetes mellitus and/or nephropathy. Atheromatous plaque was observed in 14.63% of the low-risk population. The factor with the strongest association to the presence of subclinical atherosclerosis was a moderate or high activity of RA measured by the simplified disease activity index with an odds ratio of 4.95 (95% CI: 1.53-16.01).

CONCLUSIONS

Although there was an acceptable correlation between the presence of subclinical atherosclerosis and SCOREM, there was a considerable proportion of atheromatous plaques in low-risk patients. Disease activity was the risk factor most closely associated with increased CVR.

Inflammatory and oxidative stress biomarkers in alkaptonuria: data from the DevelopAKUre project

OBJECTIVE

The aim of this work was to assess baseline serum levels of established biomarkers related to inflammation and oxidative stress in samples from alkaptonuric subjects enrolled in SONIA1 (n = 40) and SONIA2 (n = 138) clinical trials (DevelopAKUre project).

METHODS

Baseline serum levels of Serum Amyloid A (SAA), IL-6, IL-1β, TNFα, CRP, cathepsin D (CATD), IL-1ra, and MMP-3 were determined through commercial ELISA assays. Chitotriosidase activity was assessed through a fluorimetric method. Advanced Oxidation Protein Products (AOPP) were determined by spectrophotometry. Thiols, S-thiolated proteins and Protein Thiolation Index (PTI) were determined by spectrophotometry and HPLC. Patients' quality of life was assessed through validated questionnaires.

RESULTS

We found that SAA serum levels were significantly increased compared to reference threshold in 57.5% and 86% of SONIA1 and SONIA2 samples, respectively. Similarly, chitotriosidase activity was above the reference threshold in half of SONIA2 samples, whereas CRP levels were increased only in a minority of samples. CATD, IL-1β, IL-6, TNFα, MMP-3, AOPP, thiols, S-thiolated protein and PTI showed no statistically significant differences from control population. We provided evidence that alkaptonuric patients presenting with significantly higher SAA, chitotriosidase activity and PTI reported more often a decreased quality of life. This suggests that worsening of symptoms in alkaptonuria (AKU) is paralleled by increased inflammation and oxidative stress, which might play a role in disease progression.

CONCLUSIONS

Monitoring of SAA may be suggested in AKU to evaluate inflammation. Though further evidence is needed, SAA, chitotriosidase activity and PTI might be proposed as disease activity markers in AKU.

Peptidyl-prolyl cis-trans isomerase A - A novel biomarker of multi-episodic (recurrent) ocular toxoplasmosis

Ocular toxoplasmosis (OT) is the most common etiology of posterior uveitis. The high incidence of macular scarring associated with OT is a leading cause of visual morbidity. Serum biomarkers of the disease would aid in its diagnosis. This study sought, for the first time, to elucidate serum biomarkers for OT by mass spectrometry. Blood samples were collected from four groups of nine patients each; toxoplasmosis IgG-with no history of uveitis, non-toxoplasmosis uveitis, first episode OT, and symptomatic recurrent OT. Serum was isolated and subjected to proteomics analysis using 2-dimensional gel electrophoresis (2D-GE) and surface-enhanced laser desorption ionization mass spectrometry (SELDI-MS). Selected proteins were further separated by SDS-PAGE and sequenced using tandem MS. Results were cross-validated with a T. gondii outbreak biomarker database that occurred in Brazil. Fifty markers of OT and 46 markers of recurrent disease were discovered by SELDI-MS of which 30 and 15, respectively, were cross-validated. 2D-GE analysis yielded 57 bands, selected based on the intensity of the bands, leading to the identification of 20 proteins. Eleven of those identified candidates were also found by SELDI-MS. Four candidates were chosen for immunoblotting. One serum protein, peptidyl-prolyl cis-trans isomerase A (PPIA), was confirmed as a biomarker of multi-episodic OT by immunoblotting in patients. PPIA can identify the patient with active recurrent OT from acute OT, other forms of uveitis and other parasitic infections. A validated PPIA assay may have a role in the diagnosis of the atypical OT patient before more invasive anterior chamber or vitreous tap is performed for PCR analysis or for Goldmann-Witner coefficient calculations. Base-line PPIA levels need to be studied to understand its possible use when deciding for prophylactic antibiotic use in the immunosuppressed sero-positive patient.

Serum amyloid A level correlated with endoscopic findings in patients with Crohn's disease-Possible biomarker for evaluating mucosal healing

BACKGROUND

Mucosal healing (MH) has been proposed as an essential therapeutic goal for treatment of Crohn's disease (CD) patients. The utility of serum amyloid A (SAA) for prediction of MH in CD patients is lacking.

AIMS

This study was conducted to evaluate the correlation of SAA with CD-related endoscopic disease activity.

METHODS

SAA levels in serum samples obtained from CD patients as well as endoscopic findings based on a simple endoscopic score for CD (SES-CD) were assessed in relation to CD activity index (CDAI). The diagnostic ability of MH in correlation with SAA level was evaluated using receiver operating characteristic (ROC) curve analysis.

RESULTS

Fifty-five patients with CD were enrolled. Mean SAA level was significantly higher in clinical and endoscopic active phases as compared to an inactive phase. SAA level was also significantly correlated with SES-CD (r = 0.64, p < 0.01) and CDAI (r = 0.42, p < 0.01). The area under the ROC curve for SAA level was 0.77 and the optimal cut-off value for SAA to predict MH was 5.9 μg/dl. SAA level was shown to be associated with MH, with a sensitivity of 68% and specificity of 83%.

CONCLUSIONS

SAA may be a possible biomarker for evaluating MH in CD patients.

Multiplex Cytokine Analysis of Aqueous Humor in Juvenile Idiopathic Arthritis-Associated Anterior Uveitis With or Without Secondary Glaucoma

Patients with juvenile idiopathic arthritis often develop chronic anterior uveitis (JIAU). JIAU patients possess a particularly high risk for developing secondary glaucoma when inflammatory inactivity has been achieved. By using multiplex bead assay analysis, we assessed levels of pro- and anti-inflammatory cytokines, chemokines, or metalloproteinases in the aqueous humor (AH) of patients with clinically inactive JIAU with (JIAUwG) or without secondary glaucoma (JIAUwoG), or from patients with senile cataract as controls. Laser-flare photometry analysis prior to surgery showed no significant differences between JIAUwG or JIAUwoG. Compared with the control group, levels of interleukin-8, matrix metalloproteinase-2, -3, -9, serum amyloid A (SAA), transforming growth factor beta-1, -2, -3 (TGFβ-1, -2, -3), and tumor necrosis factor-alpha in the AH were significantly higher in patients with clinically inactive JIAUwG or JIAUwoG. Samples from JIAwoG patients displayed significantly higher levels of SAA (P < 0.0116) than JIAUwG patients. JIAUwG patients showed an increased level of TGFβ-2 in AH samples compared with JIAUwoG (P < 0.0009). These molecules may contribute to the clinical development of glaucoma in patients with JIAU.

Identification of potential genetic causal variants for rheumatoid arthritis by whole-exome sequencing

Rheumatoid arthritis (RA) is a highly prevalent chronic autoimmune disease. However, genetic and environmental factors involved in RA pathogenesis are still remained largely unknown. To identify the genetic causal variants underlying pathogenesis and disease progression of RA patients, we undertook the first comprehensive whole-exome sequencing (WES) study in a total of 124 subjects including 58 RA cases and 66 healthy controls in Han Chinese population. We identified 378 novel genes that were enriched with deleterious variants in RA patients using a gene burden test. The further functional effects of associated genetic genes were classified and assessed, including 21 newly identified genes that were involved in the extracellular matrix (ECM)-receptor interaction, protein digestion and absorption, focal adhesion and glycerophospholipid metabolism pathways relevant to RA pathogenesis. Moreover, six pathogenic variants were investigated and structural analysis predicted their potentially functional alteration by homology modeling. Importantly, five novel and rare homozygous variants (NCR3LG1, RAP1GAP, CHCHD5, HIPK2 and DIAPH2) were identified, which may exhibit more functional impact on RA pathogenesis. Notably, 7 genes involved in the olfactory transduction pathway were enriched and associated with RA disease progression. Therefore, we performed an efficient and powerful technique WES in Chinese RA patients and identified novel, rare and common disease causing genes that alter innate immunity pathways and contribute to the risk of RA. Findings in this study may provide potential diagnostic tools and therapeutic strategies for RA patients.

Alteration of the intestinal microbiome characterizes preclinical inflammatory arthritis in mice and its modulation attenuates established arthritis

Perturbations of the intestinal microbiome have been observed in patients with new-onset and chronic autoimmune inflammatory arthritis. However, it is currently unknown whether these alterations precede the development of arthritis or are rather a consequence of disease. Modulation of intestinal microbiota by oral antibiotics or germ-free condition can prevent arthritis in mice. Yet, the therapeutic potential of modulation of the microbiota after the onset of arthritis is not well characterized. We here show that the intestinal microbial community undergoes marked changes in the preclinical phase of collagen induced arthritis (CIA). The abundance of the phylum Bacteroidetes, specifically families S24-7 and Bacteroidaceae was reduced, whereas Firmicutes and Proteobacteria, such as Ruminococcaceae, Lachnospiraceae and Desulfovibrinocaceae, were expanded during the immune-priming phase of arthritis. In addition, we found that the abundance of lamina propria Th17, but not Th1, cells is highly correlated with the severity of arthritis. Elimination of the intestinal microbiota during established arthritis specifically reduced intestinal Th17 cells and attenuated arthritis. These effects were associated with reduced serum amyloid A expression in ileum and synovial tissue. Our observations suggest that intestinal microbiota perturbations precede arthritis, and that modulation of the intestinal microbiota after the onset of arthritis may offer therapeutic opportunities.

Periodontitis induced by bacterial infection exacerbates features of Alzheimer's disease in transgenic mice

Periodontitis is a localized infectious disease caused by periodontopathic bacteria, such as Porphyromonas gingivalis. Recently, it has been suggested that bacterial infections may contribute to the onset and the progression of Alzheimer’s disease (AD). However, we do not have any evidence about a causative relationship between periodontitis and AD. In this study, we investigated by using a transgenic mouse model of AD whether periodontitis evoked by P. gingivalis modulates the pathological features of AD. Cognitive function was significantly impaired in periodontitis-induced APP-Tg mice, compared to that in control APP-Tg mice. Levels of Amiloid β (Aβ) deposition, Aβ40, and Aβ42 in both the hippocampus and cortex were higher in inoculated APP-Tg mice than in control APP-Tg mice. Furthermore, levels of IL-1β and TNF-α in the brain were higher in inoculated mice than in control mice. The levels of LPS were increased in the serum and brain of P. gingivalis-inoculated mice. P. gingivalis LPS-induced production of Aβ40 and Aβ42 in neural cell cultures and strongly enhanced TNF-α and IL-1β production in a culture of microglial cells primed with Aβ. Periodontitis evoked by P. gingivalis may exacerbate brain Aβ deposition, leading to enhanced cognitive impairments, by a mechanism that involves triggering brain inflammation.

Alzheimer’s disease is a scourge of longevity that will drain enormous resources from health budgets in the future. Unfortunately, the pathogenesis of the disease remains an enigma and there is no adequate treatment or prophylaxis for the disease. One key priority is to examine the modifiable risk factors that influence the development of dementia. A risk factor relationship between periodontal pathogens/periodontal disease and AD exists. In Alzheimer’s model mice infected with Porphromonas gingivalis, a type of periodontopathic bacterium, cognitive function was reduced and deposition of amyloid β peptide was increased. Moreover, inflammatory cytokines and bacterial endotoxin were increased in the serum and brain. Neuroinflammation may be caused by an increase in these inflammatory mediators, and the pathology of Alzheimer’s disease may be exacerbated. Since periodontal infections are treatable, treatment of periodontal diseases during this period may be effective for delaying the onset or progression of AD.

Localization of Serum Amyloid A3 in the Mouse Ovary

Tumor necrosis factor-α (TNF-α) induces serum amyloid A (SAA) 3 among acute-phase proteins in mouse granulosa cells by activating NF-κB signaling via p55 TNF-α receptor type 1. However, the localization of SAA3 within the ovary is unknown. Here we investigated ovarian localization of SAA3 in a mouse ovulation model and in response to IL-1β, a proinflammatory mediator. For the ovulation model, equine chorionic gonadotropin (eCG; 2.5 IU) was administered to mice subcutaneously (sc) to stimulate follicular development on day 25 of age and then 50 h after eCG, human chorionic gonadotropin (hCG; 2.5 IU) was administered sc to induce ovulation. The mouse ovulation model was characterized by the localization of CYP19 mRNA expression to granulosa layers of larger follicles. SAA3 mRNA, determined by in situ hybridization, was broadly expressed throughout the whole ovary. Granulosa layers and small follicles expressed higher SAA3 mRNA compared to thecal-interstitial layers and large follicles, respectively. Interestingly, atretic follicles contained cells expressing intense SAA3 mRNA. After ovulation, SAA3 mRNA expression was intensely evident in ruptured follicles and corpora lutea (CL). The intraperitoneal administration of IL-1β revealed the intense and extensive appearance of specific cells expressing SAA3 mRNA around follicles and in CL. In addition, Gene Expression Omnibus (GEO) database analysis supported expression pattern of SAA3 mRNA observed in mouse ovulation model. Taken together, SAA3 was broadly distributed through the whole ovary, but intensely expressed in atretic follicles and CL. Furthermore, proinflammatory mediators could trigger the intense appearance of SAA3 around follicles and in CL.

Identification and Validation of SAA4 as a Rheumatoid Arthritis Prescreening Marker by Liquid Chromatography Tandem-mass Spectrometry

Rheumatoid arthritis (RA) is a chronic autoimmune disease that progresses into systemic inflammation and joint deformity. RA diagnosis is a complicated procedure, and early diagnostic methods are insufficient. Therefore, in this study, we attempted to identify new markers to improve the accuracy of RA prescreening. e identified differentially expressed proteins (DEPs) by using liquid chromatography tandem-mass spectrometry in health-prescreening sera with high rheumatoid factor (RF) values, and compared the findings with those from sera with normal RF values. We identified 93 DEPs; of these, 36 were upregulated, and 57 were downregulated in high-RF sera. Pathway analysis revealed that these DEPs were related to immune responses. Additionally, four DEPs were statistically analyzed by proteomic analysis; of these, SAA4 was significantly validated in individual enzyme-linked immunosorbent assays. Moreover, SAA4 was significantly upregulated in RA patients (n = 40, 66.43 ± 12.97 ng/mL) compared with normal controls (n = 40, 4.79 ± 0.95 ng/mL) and had a higher area under the curve than C-reactive protein. Thus, we identified SAA4 as a protein that was positively correlated with RF and RA. SAA4 may represent a novel prescreening marker for the diagnosis of RA.

Augmented Serum Amyloid A1/2 Mediated by TNF-induced NF-κB in Human Serous Ovarian Epithelial Tumors

Tumor necrosis factor-α (TNF) is well known to be involved in the immune system and ovarian inflammation. Ovarian cancer is an inflammation-related malignancy that lacks early screening strategies, resulting in late diagnosis followed by high mortality. Based on our previous data, TNF induced abundant serum amyloid A (SAA), an acute phase protein linked to inflammation, in ovarian granulosal cells. To date, the regulation and expression of SAA in ovarian cancer is not fully elucidated. Here, we investigated the relationship between TNF and SAA by comparing human normal ovarian tissues and serous ovarian tumors. We found that SAA1/2 was significantly expressed in tumor tissues, but no or trace expression levels in normal tissues. TNF was also significantly upregulated in ovarian tumor tissues compared to normal tissues. Moreover, TNF significantly increased SAA1/2 levels in human ovarian cancer cell lines, OVCAR-3 and SKOV-3, in a time-dependent manner. Since the SAA1 promoter contains two nuclear factor (NF)-κB sites, we examined whether TNF regulates SAA1 promoter activity. Deletion analysis revealed that the proximal NF-κB site (-95/-85) played a critical role in regulating TNF-induced SAA1 promoter activity. Within 2 h after intraperitoneal injection of lipopolysaccharide, a product known to stimulate release of TNF, SAA preferably localized to ovarian epithelial cells and the thecal-interstitial layers compared to granulosal cell layers. Based on Gene Expression Omnibus (GEO) database, SAA1/2 and TNF were dominantly expressed in advanced grade ovarian cancer. Taken together, the accumulation of SAA1/2 in ovarian cancer could be mediated by TNF-induced NF-κB activation.

Identification of a unique gene expression signature in mercury and 2,3,7,8-tetrachlorodibenzo-p-dioxin co-exposed cells

Mercury (Hg) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are major environmental contaminants that commonly co-occur in the environment. Both Hg and TCDD are associated with a number of human diseases including cancers. While the individual toxicological effects of Hg and TCDD have been extensively investigated, studies on co-exposure are limited to a few genes and pathways. Therefore, a significant knowledge gap exists in the understanding of the deleterious effects of co-exposure to Hg and TCDD. Due to the prevalence of Hg and TCDD co-contamination in the environment and the major human health hazards they pose, it is important to obtain a fuller understanding of genome-wide effects of Hg and TCDD co-exposure. In this study, by performing a comprehensive transcriptomic analysis of human bronchial epithelial cells (BEAS-2B) exposed to Hg and TCDD individually and in combination, we have uncovered a subset of genes with altered expression only in the co-exposed cells. We also identified the additive as well as antagonistic effects of Hg and TCDD on gene expression. Moreover, we found that co-exposure impacted several biological and disease processes not affected by Hg or TCDD individually. Our studies show that the consequences of Hg and TCDD co-exposure on the transcriptional program and biological processes could be substantially different from single exposures, thus providing new insights into the co-exposure-specific pathogenic processes.

Structure and Expression of Different Serum Amyloid A (SAA) Variants and their Concentration-Dependent Functions During Host Insults

Serum amyloid A (SAA) is, like C-reactive protein (CRP), an acute phase protein and can be used as a diagnostic, prognostic or therapy follow-up marker for many diseases. Increases in serum levels of SAA are triggered by physical insults to the host, including infection, trauma, inflammatory reactions and cancer. The order of magnitude of increase in SAA levels varies considerably, from a 10- to 100-fold during limited inflammatory events to a 1000-fold increase during severe bacterial infections and acute exacerbations of chronic inflammatory diseases. This broad response range is reflected by SAA gene duplications resulting in a cluster encoding several SAA variants and by multiple biological functions of SAA. SAA variants are single-domain proteins with simple structures and few post-translational modifications. SAA1 and SAA2 are inducible by inflammatory cytokines, whereas SAA4 is constitutively produced. We review here the regulated expression of SAA in normal and transformed cells and compare its serum levels in various disease states. At low concentrations (10-100 ng/ml), early in an inflammatory response, SAA induces chemokines or matrix degrading enzymes via Toll-like receptors and functions as an activator and chemoattractant through a G protein-coupled receptor. When an infectious or inflammatory stimulus persists, the liver continues to produce more SAA (> 1000 ng/ml) to become an antimicrobial agent by functioning as a direct opsonin of bacteria or by interference with virus infection of host cells. Thus, SAA regulates innate and adaptive immunity and this information may help to design better drugs to treat specific diseases.

End-stage renal disease in patients with rheumatoid arthritis

OBJECTIVES

To determine the frequency of end-stage renal disease (ESRD) in patients with rheumatoid arthritis (RA), the causes of ESRD, and the treatment of RA in the setting of ESRD.

METHODS

Cross-sectional study of RA (N = 3754) and non-RA (N = 326,776) patients in the United States Renal Data System (USRDS) during 2011 (N = 330,530). The epidemiology of ESRD in RA was determined and the etiology of ESRD in patients with and without RA was compared. The frequency of patients with RA with at least one filled prescription for prednisone/prednisolone, a DMARD, and/or a biologic in 2011 was determined.

RESULTS

The prevalence of RA with ESRD in the USRDS in 2011 was 1.1%. There were significant differences in age, race, sex, and BMI category between the groups (p < 0.01). Diabetes (33.5%) and hypertension (30.6%) were the most common primary causes of ESRD in patients with RA. Amyloidosis, vasculitis, and analgesic nephropathy combined accounted for less than 10% of cases of ESRD. Prednisone was the most commonly filled medication that could be used to treat RA (45.9% of RA patients). Hydroxychloroquine was the most frequently filled DMARD (13.5%); biologics were uncommon (etanercept 2.5%, adalimumab 1.5%; golimumab, infliximab, anakinra, and abatacept <1%).

CONCLUSIONS

The co-occurrence of RA with ESRD was 1.1% in the USRDS by 2011. Physicians should be aware of the critical impact of the comorbidities of diabetes and hypertension in causing ESRD in RA patients. Use of DMARDS other than hydroxychloroquine and biologics to treat RA in the setting of ESRD appears to be infrequent. Further prospective studies of treatment strategies for RA in ESRD are needed.

Differential response of serum amyloid A to different therapies in early rheumatoid arthritis and its potential value as a disease activity biomarker

Background

The aim was to compare the effect of etanercept (ETN) and conventional synthetic disease-modifying anti-rheumatic drug (DMARD) therapy on serum amyloid A (SAA) levels and to determine whether SAA reflects rheumatoid arthritis (RA) disease activity better than C-reactive protein (CRP).

Methods

We measured SAA and CRP at baseline, 24, 48, and 102 week follow-up visits in 594 patients participating in the Treatment of early RA (TEAR) study. We used Spearman correlation coefficients (rho) to evaluate the relationship between SAA and CRP and mixed effects models to determine whether ETN and methotrexate (MTX) treatment compared to triple DMARD therapy differentially lowered SAA. Akaike information criteria (AIC) were used to determine model fits.

Results

SAA levels were only moderately correlated with CRP levels (rho = 0.58, p < 0.0001). There were significant differences in SAA by both visit (p = 0.0197) and treatment arm (p = 0.0130). RA patients treated with ETN plus MTX had a larger reduction in SAA than patients treated with traditional DMARD therapy. Similar results were found for serum CRP by visit (p = 0.0254) and by treatment (p < 0.0001), with a more pronounced difference than for SAA. Across all patients and time points, models of the disease activity score of 28 joints (DAS28)-erythrocyte sedimentation rate (ESR) using SAA levels were better than models using CRP; the ΔAIC between the SAA and CRP models was 305.

Conclusions

SAA may be a better biomarker of RA disease activity than CRP, especially during treatment with tumor necrosis factor (TNF) antagonists. This warrants additional studies in other cohorts of patients on treatment for RA.

Trial registration

(ClinicalTrials.gov identifier: NCT00259610, Date of registration: 28 November 2005)