Increased levels of serum myeloperoxidase in patients with active rheumatoid arthritis

Significant correlations of upregulated MPO expression with cytokine imbalance in ankylosing spondylitis patients and the inhibitory effect mediated by mesenchymal stem cells

BACKGROUND

Little is known regarding both the role of myeloperoxidase (MPO) and the impact of mesenchymal stem cells (MSCs) on inflammatory and immune responses in ankylosing spondylitis (AS). This study is aimed to explore the role of MPO and the regulatory effect of umbilical cord-derived MSCs on MPO expression in monocytes in AS.

METHODS

MPO mRNA expression in the peripheral blood mononuclear cells (PBMCs) was detected by Real-time PCR. Cytokines including IL-2, IFN-γ, IL-17 A, IL-4, IL-10, IL-6 and TNF-α were determined by flow cytometry. A co-culture system was established by culturing THP-1 cells with MSCs at a ratio of 5:1.

RESULTS

Increased mRNA expression of MPO was observed in PBMCs of AS patients compared to healthy controls (P < 0.05). The mRNA expression of MPO was positively associated with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) (P < 0.05) in AS. Besides, the levels of IL-2, IL-10, IFN-γ, IL-17 A, IL-4, IL-6, TNF-α in plasma were notably increased in AS (P < 0.05). Positive correlations between MPO expression and IL-2, IFN -γ, IL-4, TNF-α as well as IL-6 were demonstrated in AS (P < 0.05). Furthermore, MSCs remarkably suppressed the mRNA expression of MPO along with the secretion of IL-17 A and TNF-α, but promoted IL-10 generation in monocytes.

CONCLUSION

MPO expression is significantly upregulated and correlates with cytokine imbalance in AS. It may serve as a valuable immunotherapeutic target for AS. MSCs can significantly inhibit monocyte-mediated inflammatory response potentially by downregulating MPO in monocytes.

The pivotal role of neutrophil extracellular traps in cardiovascular diseases: Mechanisms and therapeutic implications

Cardiovascular diseases (CVDs) continue to pose a significant burden on global health, prominently contributing to morbidity and mortality rates worldwide. Recent years have witnessed an increasing recognition of the intricate involvement of neutrophil extracellular traps (NETs) in the pathology of diverse cardiovascular conditions. This review provides a comprehensive analysis of the multifaceted functions of NETs in cardiovascular diseases, shedding light on the impact on atherosclerosis, myocardial infarction, heart failure, myocarditis, atrial fibrillation, aortic stenosis, and the potential therapeutic avenues targeting NETs.

(Chemical) Roles of HOCl in Rheumatic Diseases

Chronic rheumatic diseases such as rheumatoid arthritis (RA) are characterized by a dysregulated immune response and persistent inflammation. The large number of neutrophilic granulocytes in the synovial fluid (SF) from RA patients leads to elevated enzyme activities, for example, from myeloperoxidase (MPO) and elastase. Hypochlorous acid (HOCl), as the most important MPO-derived product, is a strong reactive oxygen species (ROS) and known to be involved in the processes of cartilage destruction (particularly regarding the glycosaminoglycans). This review will discuss open questions about the contribution of HOCl in RA in order to improve the understanding of oxidative tissue damaging. First, the (chemical) composition of articular cartilage and SF and the mechanisms of cartilage degradation will be discussed. Afterwards, the products released by neutrophils during inflammation will be summarized and their effects towards the individual, most abundant cartilage compounds (collagen, proteoglycans) and selected cellular components (lipids, DNA) discussed. New developments about neutrophil extracellular traps (NETs) and the use of antioxidants as drugs will be outlined, too. Finally, we will try to estimate the effects induced by these different agents and their contributions in RA.

Novel Peptides from Sturgeon Ovarian Protein Hydrolysates Prevent Oxidative Stress-Induced Dysfunction in Osteoblast Cells: Purification, Identification, and Characterization

This study aimed to explore antioxidant peptides derived from sturgeon (Acipenser schrenckii) ovaries that exhibit antiosteoporotic effects in oxidative-induced MC3T3-E1 cells. The F3-15 component obtained from sturgeon ovarian protein hydrolysates (SOPHs) via gel filtration and RP-HPLC significantly increased the cell survival rate (from 49.38 ± 2.88 to 76.26 ± 2.09%). Two putative antioxidant-acting peptides, FDWDRL (FL6) and FEGPPFKF (FF8), were screened from the F3-15 faction via liquid chromatography-tandem mass spectrometry (LC-MS/MS) and through prediction by computer simulations. Molecular docking results indicated that the possible antioxidant mechanisms of FL6 and FF8 involved blocking the active site of human myeloperoxidase (hMPO). The in vitro tests showed that FL6 and FF8 were equally adept at reducing intracellular ROS levels, increasing the activity of antioxidant enzymes, and protecting cells from oxidative injuries by inhibiting the mitogen-activated protein kinase (MAPK) pathway and activating the phosphoinositide-3 kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase-3β (GSK-3β) signaling pathway. Moreover, both peptides could increase differentiation and mineralization abilities in oxidatively damaged MC3T3-E1 cells. Furthermore, FF8 exhibited high resistance to pepsin and trypsin, showcasing potential for practical applications.

Anti-rheumatoid arthritis potential of Halodule pinifolia: development, characterization and in vivo evaluation of H. pinifolia-based oral suspension and lipid nano-emulsion

For treating chronic diseases like rheumatoid arthritis, herbal medicines are preferred due to their evident therapeutic effects and lesser side effects as compared to the long-term used conventional drugs. In this study, the anti-rheumatoid arthritis effect of an unexplored marine grass Halodule pinifolia (HP), and a combination of it with Glycyrrhiza glabra (liquorice; LQ), prepared as a conventional suspension (C1) and a lipid nano-emulsion (C1-N) was evaluated in Freund's complete adjuvant (FCA)- and collagen-induced arthritis (CIA) models. Formulations C1 and C1-N contained standardized extract HP (100 mg/kg) as major active ingredient and liquorice LQ (50 mg/kg) as both active ingredient (anti-inflammatory and anti-ulcer) and sweetening agent. Oral administration of HP and C1 to FCA-induced Sprague-Dawley rats significantly reduced the paw oedema, spleen index, controlled the haematological parameters, cytokine levels (IL-1β, IL-6, TNF-α estimated by ELISA), mRNA expression of cytokines and osteoclast markers (RANK, TRAP and cathepsin K measured by RTPCR). Histopathology and radiological scanning demonstrated lesser joint deterioration in sample-treated rats, as evident phenotypically. The downregulation of CD51 and MMP-3 (western blot) corroborated the anti-arthritic effect of HP and C1. HP showed better results among all. Further, under the CIA model, both C1 and C1-N were found to be potentially active as evidenced by their effect on rat paw oedema, spleen index, haematological parameters, rheumatoid factor, cytokines, osteoclast markers, histology and X-rays. The results proved the anti-arthritic effect of HP and the formulations, particularly the lipid nano-emulsion that showed improved stability as well as activity.

Salivary and serum levels of neutrophil proteases in periodontitis and rheumatoid arthritis

OBJECTIVE

The aim was to profile serum and salivary levels of active-matrix metalloproteinase (aMMP)-8, tissue inhibitor MMP (TIMP)-1, aMMP-8/TIMP-1 ratio, total MMP (tMMP)-9, tMMP-9/TIMP-1 ratio, myeloperoxidase (MPO), and human neutrophil elastase (HNE) in periodontitis and rheumatoid arthritis (RA).

MATERIALS AND METHODS

Rheumatoid arthritis patients with periodontitis (RA + P, n = 26), periodontally healthy RA patients (RA, n = 23), systemically healthy periodontitis patients (P, n = 24), and controls (C, n = 24) were included. aMMP-8 levels were determined by a time-resolved immunofluorescence assay (IFMA), TIMP-1, tMMP-9, MPO, and HNE levels were measured by enzyme-linked immunosorbent (ELISA) assays.

RESULTS

Higher salivary aMMP-8 (p < 0.001), aMMP-8/TIMP-1 ratio (p = 0.043), tMMP-9 (p = 0.011), tMMP-9/TIMP-1 ratio (p = 0.022), MPO (p = 0.026) and HNE (p < 0.001) levels were detected in P relative to the controls. Salivary TIMP-1 was increased in RA patients regardless of periodontal status (RA + P vs. P: p = 0.038; RA vs. C: p = 0.020). Serum neutrophil proteases were increased in RA groups (RA + P, RA) compared to systemically healthy groups (P, C) (p < 0.05).

CONCLUSIONS

Serum levels of neutrophil proteases were increased in RA study groups; however rheumatologic status seemingly does not affect salivary levels of these proteins.

Free Radical Lipid Peroxidation Induced by Reactive Halogen Species

The review is devoted to the mechanisms of free radical lipid peroxidation (LPO) initiated by reactive halogen species (RHS) produced in mammals, including humans, by heme peroxidase enzymes, primarily myeloperoxidase (MPO). It has been shown that RHS can participate in LPO both in the initiation and branching steps of the LPO chain reactions. The initiation step of RHS-induced LPO mainly involves formation of free radicals in the reactions of RHS with nitrite and/or with amino groups of phosphatidylethanolamine or Lys. The branching step of the oxidative chain is the reaction of RHS with lipid hydroperoxides, in which peroxyl and alkoxyl radicals are formed. The role of RHS-induced LPO in the development of human inflammatory diseases (cardiovascular and neurodegenerative diseases, cancer, diabetes, rheumatoid arthritis) is discussed in detail.

Study on Potential Differentially Expressed Genes in Idiopathic Pulmonary Fibrosis by Bioinformatics and Next-Generation Sequencing Data Analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.

Zerumbone Protects Rats from Collagen-Induced Arthritis by Inhibiting Oxidative Outbursts and Inflammatory Cytokine Levels

Rheumatoid arthritis (RA) is an immunocompromised disorder characterized by a marked increase in the synthesis of inflammatory molecules that stimulates the destruction of bones and cartilage. The conventional treatment modalities for RA are associated with adverse side effects and lack sensitivity, suggesting an immediate demand for alternate beneficial therapeutic remedies. The current study sought to understand more about zerumbone's anti-inflammatory properties in diagnosing collagen-induced arthritis (CIA) in experimental animals. The current study observed that zerumbone reduced clinical severity in CIA-induced animals compared to healthy animals. Zerumbone administration significantly decreased (p < 0.001) the concentration of SOD, CAT, GR, and GSH in treatment groups. Zerumbone administration drove down significantly (p < 0.001) the concentration of inflammatory cytokine molecules. Zerumbone was effective in bringing significant changes in levels of MPO, NO, LDH, MMP-8, and ELA. The therapeutic potential of zerumbone was found to be associated with reduced joint destruction and restored normal histology in the cartilage and tissue. Adsorption, distribution, metabolism, excretion, and toxicity studies were used to determine the druglike properties of zerumbone. ProTox-II studies revealed that zerumbone did not possess toxic properties like hepatotoxicity, immunotoxicity, carcinogenicity, mutagenicity, and cytotoxicity. Therefore, the present study evaluated the therapeutic properties of zerumbone in CIA animal models.

Effects of One-Year Tofacitinib Therapy on Lipids and Adipokines in Association with Vascular Pathophysiology in Rheumatoid Arthritis

Background: Cardiovascular (CV) morbidity, mortality and metabolic syndrome are associated with rheumatoid arthritis (RA). A recent trial has suggested increased risk of major CV events (MACE) upon the Janus kinase (JAK) inhibitor tofacitinib compared with anti-tumor necrosis factor α (TNF-α) therapy. In our study, we evaluated lipids and other metabolic markers in relation to vascular function and clinical markers in RA patients undergoing one-year tofacitinib therapy. Patients and methods: Thirty RA patients treated with either 5 mg or 10 mg bid tofacitinib were included in a 12-month follow-up study. Various lipids, paraoxonase (PON1), myeloperoxidase (MPO), thrombospondin-1 (TSP-1) and adipokine levels, such as adiponectin, leptin, resistin, adipsin and chemerin were determined. In order to assess flow-mediated vasodilation (FMD), common carotid intima-media thickness (IMT) and arterial pulse-wave velocity (PWV) ultrasonography were performed. Assessments were carried out at baseline, and 6 and 12 months after initiating treatment. Results: One-year tofacitinib therapy significantly increased TC, HDL, LDL, APOA, APOB, leptin, adipsin and TSP-1, while significantly decreasing Lp(a), chemerin, PON1 and MPO levels. TG, lipid indices (TC/HDL and LDL/HDL), adiponectin and resistin showed no significant changes. Numerous associations were found between lipids, adipokines, clinical markers and IMT, FMD and PWV (p < 0.05). Regression analysis suggested, among others, association of BMI with CRP and PWV (p < 0.05). Adipokines variably correlated with age, BMI, CRP, CCP, FMD, IMT and PWV, while MPO, PON1 and TSP-1 variably correlated with age, disease duration, BMI, RF and PWV (p < 0.05). Conclusions: JAK inhibition by tofacitinib exerts balanced effects on lipids and other metabolic markers in RA. Various correlations may exist between metabolic, clinical parameters and vascular pathophysiology during tofacitinib treatment. Complex assessment of lipids, metabolic factors together with clinical parameters and vascular pathophysiology may be utilized in clinical practice to determine and monitor the CV status of patients in relation with clinical response to JAK inhibition.

Hypochlorous Acid Chemistry in Mammalian Cells—Influence on Infection and Role in Various Pathologies

This review discusses the formation of hypochlorous acid HOCl and the role of reactive chlorinated species (RCS), which are catalysed by the enzyme myeloperoxidase MPO, mainly located in leukocytes and which in turn contribute to cellular oxidative stress. The reactions of RCS with various organic molecules such as amines, amino acids, proteins, lipids, carbohydrates, nucleic acids, and DNA are described, and an attempt is made to explain the chemical mechanisms of the formation of the various chlorinated derivatives and the data available so far on the effects of MPO, RCS and halogenative stress. Their presence in numerous pathologies such as atherosclerosis, arthritis, neurological and renal diseases, diabetes, and obesity is reviewed and were found to be a feature of debilitating diseases.

Discovery of AZD4831, a Mechanism-Based Irreversible Inhibitor of Myeloperoxidase, As a Potential Treatment for Heart Failure with Preserved Ejection Fraction

Myeloperoxidase is a promising therapeutic target for treatment of patients suffering from heart failure with preserved ejection fraction (HFpEF). We aimed to discover a covalent myeloperoxidase inhibitor with high selectivity for myeloperoxidase over thyroid peroxidase, limited penetration of the blood-brain barrier, and pharmacokinetics suitable for once-daily oral administration at low dose. Structure-activity relationship, biophysical, and structural studies led to prioritization of four compounds for in-depth safety and pharmacokinetic studies in animal models. One compound (AZD4831) progressed to clinical studies on grounds of high potency (IC₅₀, 1.5 nM in vitro) and selectivity (>450-fold vs thyroid peroxidase in vitro), the mechanism of irreversible inhibition, and the safety profile. Following phase 1 studies in healthy volunteers and a phase 2a study in patients with HFpEF, a phase 2b/3 efficacy study of AZD4831 in patients with HFpEF started in 2021.

Inflammatory signature in acute-on-chronic liver failure includes increased expression of granulocyte genes ELANE, MPO and CD177

Acute-on-Chronic Liver Failure (ACLF) is associated with innate immune dysfunction and high short-term mortality. Neutrophils have been identified to influence prognosis in ACLF. Neutrophil biology is under-evaluated in ACLF. Therefore, we investigated neutrophil-specific genes and their association with ACLF outcomes. This is an observational study. Enriched granulocytes, containing neutrophils, isolated from study participants in three groups- ACLF(n = 10), chronic liver disease (CLD, n = 4) and healthy controls (HC, n = 4), were analysed by microarray. Differentially expressed genes were identified and validated by qRT-PCR in an independent cohort of ACLF, CLD and HC (n = 30, 15 and 15 respectively). The association of confirmed overexpressed genes with ACLF 28-day non-survivors was investigated. The protein expression of selected neutrophil genes was confirmed using flow cytometry and IHC. Differential gene expression analysis showed 1140 downregulated and 928 upregulated genes for ACLF versus CLD and 2086 downregulated and 1091 upregulated genes for ACLF versus HC. Significant upregulation of neutrophilic inflammatory signatures were found in ACLF compared to CLD and HC. Neutrophil enriched genes ELANE, MPO and CD177 were highly upregulated in ACLF and their expression was higher in ACLF 28-day non-survivors. Elevated expression of CD177 protein on neutrophil surface in ACLF was confirmed by flow cytometry. IHC analysis in archival post mortem liver biopsies showed the presence of CD177+ neutrophils in the liver tissue of ACLF patients. Granulocyte genes ELANE, MPO and CD177 are highly overexpressed in ACLF neutrophils as compared to CLD or HC. Further, this three-gene signature is highly overexpressed in ACLF 28-day non-survivors.

Role of myeloperoxidase and oxidant formation in the extracellular environment in inflammation-induced tissue damage

The heme peroxidase family generates a battery of oxidants both for synthetic purposes, and in the innate immune defence against pathogens. Myeloperoxidase (MPO) is the most promiscuous family member, generating powerful oxidizing species including hypochlorous acid (HOCl). Whilst HOCl formation is important in pathogen removal, this species is also implicated in host tissue damage and multiple inflammatory diseases. Significant oxidant formation and damage occurs extracellularly as a result of MPO release via phagolysosomal leakage, cell lysis, extracellular trap formation, and inappropriate trafficking. MPO binds strongly to extracellular biomolecules including polyanionic glycosaminoglycans, proteoglycans, proteins, and DNA. This localizes MPO and subsequent damage, at least partly, to specific sites and species, including extracellular matrix (ECM) components and plasma proteins/lipoproteins. Biopolymer-bound MPO retains, or has enhanced, catalytic activity, though evidence is also available for non-catalytic effects. These interactions, particularly at cell surfaces and with the ECM/glycocalyx induce cellular dysfunction and altered gene expression. MPO binds with higher affinity to some damaged ECM components, rationalizing its accumulation at sites of inflammation. MPO-damaged biomolecules and fragments act as chemo-attractants and cell activators, and can modulate gene and protein expression in naïve cells, consistent with an increasing cycle of MPO adhesion, activity, damage, and altered cell function at sites of leukocyte infiltration and activation, with subsequent tissue damage and dysfunction. MPO levels are used clinically both diagnostically and prognostically, and there is increasing interest in strategies to prevent MPO-mediated damage; therapeutic aspects are not discussed as these have been reviewed elsewhere.

Evaluation of dysfunctional high-density lipoprotein levels with myeloperoxidase/paraoxonase-1 ratio in rheumatoid arthritis

BACKGROUND

The aim of this study is to evaluate dysfunctional high-density lipoprotein cholesterol (HDL) by measuring myeloperoxidase (MPO)/paraoxonase 1 (PON1) ratio in patients with rheumatoid arthritis (RA) and to investigate the relationship between dysfunctional HDL and cardiovascular disease (CVD) in RA patients.

METHODS

Sixty-seven healthy individuals and 130 RA patients were included in the study. Routine lipid panels (triglyceride (TG), low-density lipoprotein cholesterol (LDL), HDL, total cholesterol (TC), PON1 and MPO levels were measured. Disease activity scores-28 (DAS28) of RA patients were calculated. Cardiological examination records of the patients were assessed to detect patients who also have CVD.

RESULTS

There were no significant differences between RA and control groups in routine lipid profiles (P > .05 for all). MPO/PON1 ratios were significantly elevated in the RA group compared with the control group (P < .001). MPO/PON1 ratios were higher in RA patients with CVD history compared with those without CVD (P < .05). MPO/PON1 ratios were correlated with DAS28 scores (rho: 0.357, P < .001).

CONCLUSION

HDL dysfunction determined by the MPO/PON1 ratio may be associated with the pathophysiology of increased CVD in RA. Thus, evaluating dysfunctional HDL levels by measuring the MPO/PON1 ratio in RA patients may allow more detailed patient follow-up, as well as the reduction of CVD events in RA patients with therapeutic agents aiming to increase the functional properties of HDL by decreasing this ratio.

Activation of the Nrf2/HO-1 signaling pathway by dimethyl fumarate ameliorates complete Freund's adjuvant-induced arthritis in rats

The nuclear factor erythroid 2-related factor (Nrf2) signaling pathway has recently emerged as a novel therapeutic target in treating various diseases. Therefore, the present study aimed to assess the protective role of the Nrf2 activator, dimethyl fumarate (DMF) in the complete Freund's adjuvant (CFA)- induced arthritis model. DMF (25, 50, and 100 mg/kg) and dexamethasone (2 mg/kg) were orally administered for 14 days. Pain-related tests, paw volume, and arthritic scores were measured weekly. Serum TNF-α, IL-1β, cyclic citrullinated peptide (CCP), C-reactive protein (CRP), and rheumatoid factor (RF) levels were estimated. Nitrite, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH), catalase (CAT), and myeloperoxidase (MPO) levels were also evaluated. NF-κB, Nrf2, HO-1, and COX-2 levels were estimated in the joint tissue. DMF treatment exerted anti-arthritic activity by enhancing the nociceptive threshold, improving arthritis scores, and reducing paw edema. Also, DMF suppressed changes in oxidative stress markers and inflammatory mediators and enhanced Nrf2 and HO-1 levels in CFA-injected rats. These findings indicate that the anti-arthritic activity of DMF may be mediated by the activation of the Nrf2/HO-1 pathway, which reduced oxidative damage and inflammation.

Chalcones and their B-aryl analogues as myeloperoxidase inhibitors: In silico, in vitro and ex vivo investigations

In the present study, a series of chalcones and their B-aryl analogues were prepared and evaluate as inhibitors of myeloperoxidase (MPO) chlorinating activity, using in vitro and ex vivo assays. Among these, B-thiophenyl chalcone (analogue 9) demonstrated inhibition of in vitro and ex vivo MPO chlorinating activity, exhibiting IC₅₀ value of 0.53 and 19.2 µM, respectively. Potent ex vivo MPO inhibitors 5, 8 and 9 were not toxic to human neutrophils at 50 µM, as well as displayed weak 2,2-diphenyl-1-pycrylhydrazyl radical (DPPH•) and hypochlorous acid (HOCl) scavenger abilities. Docking simulations indicated binding mode of MPO inhibitors, evidencing hydrogen bonds between the amino group at 4'position (ring A) of chalcones with Gln91, Asp94, and Hys95 MPO residues. In this regard, the efficacy and low toxicity promoted aminochalcones and arylic analogues to the rank of hit compounds in the search for new non-steroidal anti-inflammatory compounds.

The effect of immobilized antioxidant enzymes on the oxidative stress in UV-irradiated rat skin

Aim: Superoxide dismutase (SOD) and catalase (CAT) immobilized on gold nanoparticles (AuNP) and silver nanoparticles (AgNP) nanoparticles were used to reduce UV radiation-induced oxidative stress in rat skin. Materials & methods: The antioxidant influence of the enzymes was investigated on level of malondialdehyde, 8-hydroksy-2'deoksyguanozine, myeloperoxidase, total antioxidant capacity, SOD2 and CAT activity and expression, and glutathione and glutathione peroxidase activity. Results: The application of immobilized SOD and CAT on UV-irradiated skin reduced malondialdehyde and 8-hydroksy-2'deoksyguanozine levels also SOD and CAT activity and expression increased. The tested enzymes influence glutathione peroxidase activity and level of total antioxidant capacity and glutathione. Conclusion: Immobilized enzymes increased the antioxidative potential of skin following UV irradiation.

Oxidative and Antioxidative Stress Linked Biomarkers in Ankylosing Spondylitis: A Systematic Review and Meta-analysis

Objective. Ankylosing spondylitis (AS) is a chronic inflammatory disease that affects the axial skeleton, leading to joint disability. Our study aims at investigating the change of oxidative and antioxidative stress linked biomarkers in AS. Methods. This systematic review and meta-analysis was performed following the Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, Web of Science, and Cochrane Library databases till May 2020 were searched. Only articles published in English were included. Two reviewers screened relevant studies, extracted data, and assessed the quality of included studies using the Newcastle-Ottawa scale independently. Either random or fixed effect model was adopted base on the heterogeneity testing by $I^2$ statistic. Standardized mean difference (SMD) and 95% confidence intervals (CI) of oxidative and antioxidative markers were calculated. $p$ value <0.05 was considered statistically significant. Results. A total of 22 studies including 931 AS patients and 917 healthy controls met the selection criteria. Significantly increased levels of all oxidative stress markers except myeloperoxidase, and significantly decreased levels of total antioxidant status ( $\text{SMD}=-1.19$ , 95% CI -2.35 to -0.03, $p=0.044$ ) and paraoxonase 1( $\text{SMD}=-1.01$ , 95% CI -1.78 to -0.24, $p=0.010$ ) in serum were observed in AS patients when compared with healthy controls. However, there were no significant differences of all oxidative and anti-oxidative stress biomarkers in erythrocytes. Additionally, the levels of malondialdehyde ( $\text{SMD}=0.51$ , 95% CI 0.21 to 0.81, $p=0.001$ ) and advanced oxidation protein products ( $\text{SMD}=0.95$ , 95% CI 0.58 to 1.31, $p<0.001$ ) in serum were significantly higher in active patients when compared with inactive AS patients. Conclusion. This meta-analysis demonstrated an overall increase of oxidative markers and decrease of antioxidative markers in AS, suggesting that oxidative stress may play an important role in the pathogenesis of AS.

The Role of Myeloperoxidase in Biomolecule Modification, Chronic Inflammation, and Disease

Significance: The release of myeloperoxidase (MPO) by activated leukocytes is critical in innate immune responses. MPO produces hypochlorous acid (HOCl) and other strong oxidants, which kill bacteria and other invading pathogens. However, MPO also drives the development of numerous chronic inflammatory pathologies, including atherosclerosis, neurodegenerative disease, lung disease, arthritis, cancer, and kidney disease, which are globally responsible for significant patient mortality and morbidity. Recent Advances: The development of imaging approaches to precisely identify the localization of MPO and the molecular targets of HOCl in vivo is an important advance, as typically the involvement of MPO in inflammatory disease has been inferred by its presence, together with the detection of biomarkers of HOCl, in biological fluids or diseased tissues. This will provide valuable information in regard to the cell types responsible for releasing MPO in vivo, together with new insight into potential therapeutic opportunities. Critical Issues: Although there is little doubt as to the value of MPO inhibition as a protective strategy to mitigate tissue damage during chronic inflammation in experimental models, the impact of long-term inhibition of MPO as a therapeutic strategy for human disease remains uncertain, in light of the potential effects on innate immunity. Future Directions: The development of more targeted MPO inhibitors or a treatment regimen designed to reduce MPO-associated host tissue damage without compromising pathogen killing by the innate immune system is therefore an important future direction. Similarly, a partial MPO inhibition strategy may be sufficient to maintain adequate bacterial activity while decreasing the propagation of inflammatory pathologies.

Atherosclerosis in Rheumatoid Arthritis: Promoters and Opponents

Substantial epidemiological data identified cardiovascular (CV) diseases as a main cause of mortality in patients with rheumatoid arthritis (RA). In light of this, RA patients may benefit from additional CV risk screening and more intensive prevention strategies. Nevertheless, current algorithms for CV risk stratification still remain tailored on general population and are burdened by a significant underestimation of CV risk in RA patients. Acute CV events in patients with RA are largely related to an accelerated atherosclerosis. As pathophysiological features of atherosclerosis overlap those occurring in the inflamed RA synovium, the understanding of those common pathways represents an urgent need and a leading challenge for CV prevention in patients with RA. Genetic background, metabolic status, gut microbiome, and systemic inflammation have been also suggested as additional key pro-atherosclerotic factors. The aim of this narrative review is to update the current knowledge about pathophysiology of atherogenesis in RA patients and potential anti-atherosclerotic effects of disease-modifying anti-rheumatic drugs.

Systemic levels of anti-PAD4 autoantibodies correlate with airway obstruction in cystic fibrosis

Cystic fibrosis (CF) airway disease is characterized by the long-term presence of neutrophil granulocytes. Formation of neutrophil extracellular traps (NETs) and/or autoantibodies directed against extracellular components of NETs are possible contributors to neutrophil-mediated lung damage in CF. The goal of this study was to measure their levels in CF adults compared to healthy controls and subjects with rheumatologic diseases known to develop NET-related autoantibodies and pathologies, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Sera were analyzed from the following number of subjects: 37 CF, 23 healthy controls (HC), 20 RA, and 21 SLE. CF had elevated serum myeloperoxidase (MPO) concentrations (347.5±56.1 ng/ml, mean+/-S.E.M., p = .0132) compared to HC (144.5±14.6 ng/ml) but not of neutrophil elastase (NE) complexed with alpha-1-antitrypsin, cell-free DNA or NE-DNA complexes. The peptidylarginine deiminase 4 (PAD4) enzyme is required for NET formation and associated DNA release in neutrophils. Serum levels of anti-PAD4 antibodies (Ab) were elevated in CF (p = .0147) compared to HC and showed an inverse correlation with a measure of lung function, FEV1% predicted (r = -0.5020, p = .015), as did MPO levels (r = -0.4801, p = .0026). Anti-PAD4 Ab levels in CF sera associated with lung infection by P. aeruginosa, but not that by S. aureus, age, sex, CF-related diabetes or the presence of musculoskeletal pain. Serum levels of anti-citrullinated protein Abs (ACPAs) and anti-nucleosome Abs were not elevated in CF compared to HC (p = .7498, p = .0678). In summary, adult CF subjects develop an autoimmune response against NET components that correlates with worsening lung disease.

Regenerative effects of glycyrrhizin and/or platelet rich plasma on type-II collagen induced arthritis: Targeting autophay machinery markers, inflammation and oxidative stress

Rheumatoid arthritis (RA) is a systemic chronic autoimmune disease manifested by joint destruction and deformity, hence decreasing patient's life quality. The aim of the present work is to explore the mechanistic effects of glycyrrhizin (GL)and/or platelet rich plasma (PRP) treatment on collagen induced arthritis. 75 female Wistar rats were allocated into five equal groups. Group I: control group. Group II: arthritis group (A group); arthritis was induced by type-II collagen Group III: Glycyrrhizin treated group(A + GL group), Group IV: platelet rich plasma treated group(A + PRP group)and Group V: combined treatment group(A + GL + PRP group). Hind paw joint tissue levels of high-mobility group box 1 protein (HMGB-1), beclin-1 and nuclear factor (erythroid-2)-related factor 2 (Nrf2) DNA binding activity were detected by ELISA. Activities of myeloperoxidase (MPO) and catalase enzymes were determined spectrophotometrically. mRNA expression levels of microtubule associated protein light chain 3 (LC3) was detected by quantitative real time PCR. After 8 weeks treatment, there was improvement of inflammation and autophagy biomarkers by the significant reduction of HMGB-1 and beclin-1 levels, down regulation ofLC3mRNA expression. On the other hand, we monitored restoration of the anti-oxidant status through the inhibited MPO activity besides induction of both catalase and Nrf2-DNA binding activities. It could be concluded that, the mutual use of both PRP and GL had a greater effect than each alone against arthritis which is considered a novel finding that can highlight the regenerative and ameliorative effects of this combined treatmentthus launching promising avenues for RA treatment.

Neutrophils and type 1 diabetes: current knowledge and suggested future directions

PURPOSE OF REVIEW

Purpose of this review is to describe the most recent human studies on neutrophils in type 1 diabetes (T1D) and to focus on the key questions that still need to be addressed.

RECENT FINDINGS

Recent evidences demonstrate that neutrophils have marked abnormalities in phenotype and function and play a central role in initiation and perpetuation of aberrant immune responses and organ damage in various systemic autoimmune diseases such as lupus erythematosus and rheumatoid arthritis. In T1D, we have recently demonstrated that reduced circulating neutrophil numbers precede and accompany the disease and that neutrophils infiltrate the pancreas and extrude neutrophil extracellular traps already before the onset of clinical symptoms. However, few other evidences of alterations in neutrophil phenotype and function have been reported in humans, especially in the T1D presymptomatic phases.

SUMMARY

Dissecting the pathogenic role of these cells in human T1D is crucial for a better understanding of the disease and to open new therapeutic opportunities.

Neutrophils and NETs in modulating acute and chronic inflammation

Neutrophils are an absolutely essential part of the innate immune system, playing an essential role in the control of infectious diseases but more recently are also being viewed as important players in tissue repair. Neutrophils are able to counteract an infection through phagocytosis and/or the release of neutrophil extracellular traps (NETs). By contrast, neutrophils help repair damaged tissues, limiting NET production but still phagocytosing debris. However, when inflammation is recurrent, or the inciting agent persists, neutrophils through a frustrated inability to resolve the problem can release NETs to exacerbate tissue damage during inappropriate inflammation. In this review, we discuss the mechanisms of NET formation, as well as the apparent paradoxical role of neutrophils and NETs in host defense, chronic inflammation, and tissue disrepair.

Caught in a Trap? Proteomic Analysis of Neutrophil Extracellular Traps in Rheumatoid Arthritis and Systemic Lupus Erythematosus

Neutrophil Extracellular Traps (NETs) are implicated in the development of auto-immunity in diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) through the externalization of intracellular neoepitopes e.g., dsDNA and nuclear proteins in SLE and citrullinated peptides in RA. The aim of this work was to use quantitative proteomics to identify and measure NET proteins produced by neutrophils from healthy controls, and from patients with RA and SLE to determine if NETs can be differentially-generated to expose different sets of neoepitopes. Ultra-pure neutrophils (>99%) from healthy individuals (n = 3) and patients with RA or SLE (n = 6 each) were incubated ± PMA (50 nM, PKC super-activator) or A23187 (3.8 μM, calcium ionophore) for 4 h. NETs were liberated by nuclease digestion and concentrated onto Strataclean beads prior to on-bead digestion with trypsin. Data-dependent LC-MS/MS analyses were conducted on a QExactive HF quadrupole-Orbitrap mass spectrometer, and label-free protein quantification was carried out using Progenesis QI. PMA-induced NETs were decorated with annexins, azurocidin and histone H3, whereas A23187-induced NETs were decorated with granule proteins including CAMP/LL37, CRISP3, lipocalin and MMP8, histones H1.0, H1.4, and H1.5, interleukin-8, protein-arginine deiminase-4 (PADI4), and α-enolase. Four proteins were significantly different between PMA-NETs from RA and SLE neutrophils (p < 0.05): RNASE2 was higher in RA, whereas MPO, leukocyte elastase inhibitor and thymidine phosphorylase were higher in SLE. For A23187-NETs, six NET proteins were higher in RA (p < 0.05), including CAMP/LL37, CRISP3, interleukin-8, MMP8; Thirteen proteins were higher in SLE, including histones H1.0, H2B, and H4. This work provides the first, direct comparison of NOX2-dependent (PMA) and NOX2-independent (A23187) NETs using quantitative proteomics, and the first direct comparison of RA and SLE NETs using quantitative proteomics. We show that it is the nature of the stimulant rather than neutrophil physiology that determines NET protein profiles in disease, since stimulation of NETosis in either a NOX2-dependent or a NOX2-independent manner generates broadly similar NET proteins irrespective of the disease background. We also use our proteomics pipeline to identify an extensive range of post-translationally modified proteins in RA and SLE, including histones and granule proteins, many of which are known targets of auto-antibodies in each disease.

Network Pharmacology-Based Investigation of Protective Mechanism of Aster tataricus on Lipopolysaccharide-Induced Acute Lung Injury

Acute lung injury (ALI) is a common clinical condition that badly influences people's health. Recent studies indicated that Aster tataricus (RA) had potential effects on ALI, but the effective components and their mechanism is not clear. In this study, we found that the Fraction-75 eluted from RA extract could significantly protect the lipopolysaccharide (LPS)-induced ALI in mice, including alleviating the severity of lung pathology, attenuating the pulmonary edema, and reducing the release of inflammatory cells. Further ingredient analyses demonstrated that there were mainly 16 components in it, among which 10 components were collected according to their relative peak area and oral bioavailability. Next, the components-disease targets network suggested that the candidate components had extensive associations with 49 known therapeutic targets of ALI, among which 31 targets could be regulated by more than one component. Herein, GO functional and pathway analysis revealed that the common targets were associated with four biological processes, including the inflammatory response to stimulus, cellular process, chemokine biosynthetic process and immune system process. Furthermore, the ELISA validation indicated that the candidate components in RA extract may protect the LPS-induced ALI mainly through inhibiting the release of inflammatory cytokines and promoting the repair of vascular endothelial.

Hide and seek

A 51-year-old woman with a previous history of rheumatoid arthritis experienced painless progressive visual loss in the left eye for 3 weeks. Fundus examination revealed optic disk pallor in her left eye. Magnetic resonance imaging of the brain and orbits showed enhancement of the pachymeninges and hypersignal at the left optic nerve. Meningeal biopsy was performed. Immunohistochemical staining for IgG4 revealed several IgG4-positive plasma cells, which in some areas reached the number of 50 cells/high-power field. In this case, the clinical and histopathological features of the patient met diagnostic criteria for rheumatoid arthritis and IgG4-related disease, respectively. Rheumatoid arthritis sometimes occurs with abundant IgG4 plasma cells and fulfills the histological diagnostic criteria for IgG4-related disease. This case demonstrates that overlapping features of IgG4-RD and rheumatoid arthritis may present in a single patient.

Programmed Necrosis and Disease:We interrupt your regular programming to bring you necroinflammation

Compared to the tidy and immunologically silent death during apoptosis, necrosis seems like a chaotic and unorganized demise. However, we now recognize that there is a method to its madness, as many forms of necrotic cell death are indeed programmed and function beyond lytic cell death to support homeostasis and immunity. Inherently more immunogenic than their apoptotic counterpart, programmed necrosis, such as necroptosis, pyroptosis, ferroptosis, and NETosis, releases inflammatory cytokines and danger-associated molecular patterns (DAMPs), skewing the milieu to a pro-inflammatory state. Moreover, impaired clearance of dead cells often leads to inflammation. Importantly, these pathways have all been implicated in inflammatory and autoimmune diseases, therefore careful understanding of their molecular mechanisms can have long lasting effects on how we interpret their role in disease and how we translate these mechanisms into therapy.

Abnormal neutrophil signature in the blood and pancreas of presymptomatic and symptomatic type 1 diabetes

BACKGROUND

Neutrophils and their inflammatory mediators are key pathogenic components in multiple autoimmune diseases, while their role in human type 1 diabetes (T1D), a disease that progresses sequentially through identifiable stages prior to the clinical onset, is not well understood. We previously reported that the number of circulating neutrophils is reduced in patients with T1D and in presymptomatic at-risk subjects. The aim of the present work was to identify possible changes in circulating and pancreas-residing neutrophils throughout the disease course to better elucidate neutrophil involvement in human T1D.

METHODS

Data collected from 389 subjects at risk of developing T1D, and enrolled in 4 distinct studies performed by TrialNet, were analyzed with comprehensive statistical approaches to determine whether the number of circulating neutrophils correlates with pancreas function. To obtain a broad analysis of pancreas-infiltrating neutrophils throughout all disease stages, pancreas sections collected worldwide from 4 different cohorts (i.e., nPOD, DiViD, Siena, and Exeter) were analyzed by immunohistochemistry and immunofluorescence. Finally, circulating neutrophils were purified from unrelated nondiabetic subjects and donors at various T1D stages and their transcriptomic signature was determined by RNA sequencing.

RESULTS

Here, we show that the decline in β cell function is greatest in individuals with the lowest peripheral neutrophil numbers. Neutrophils infiltrate the pancreas prior to the onset of symptoms and they continue to do so as the disease progresses. Of interest, a fraction of these pancreas-infiltrating neutrophils also extrudes neutrophil extracellular traps (NETs), suggesting a tissue-specific pathogenic role. Whole-transcriptome analysis of purified blood neutrophils revealed a unique molecular signature that is distinguished by an overabundance of IFN-associated genes; despite being healthy, said signature is already present in T1D-autoantibody-negative at-risk subjects.

CONCLUSIONS

These results reveal an unexpected abnormality in neutrophil disposition both in the circulation and in the pancreas of presymptomatic and symptomatic T1D subjects, implying that targeting neutrophils might represent a previously unrecognized therapeutic modality.

FUNDING

Juvenile Diabetes Research Foundation (JDRF), NIH, Diabetes UK.

Presence of Autoantibodies in Erosive Hand Osteoarthritis and Association with Clinical Presentation

OBJECTIVE

To investigate whether 3 rheumatoid arthritis-associated antibodies [rheumatoid factor (RF) and anticitrullinated protein antibodies (ACPA) or anticarbamylated protein (anti-CarP) antibodies] are present in hand osteoarthritis (HOA) and associate with erosive OA (EOA).

METHODS

Anti-CarP IgG was measured by ELISA in baseline sera of patients with HOA from 3 cohorts: HOSTAS (n = 510, 27.2% EOA), ECHO (n = 47), and EHOA (n = 23), and in sera of healthy controls (HC; n = 196, mean age 44.1 yrs, 51.0% women). Moreover, ACPA-IgG and RF-IgM were additionally determined in HOSTAS and HC. The prevalence of autoantibodies was compared between HOA and HC and between erosive and nonerosive HOA. In HOSTAS, hand radiographs were scored (Kellgren-Lawrence, Osteoarthritis Research Society International osteophyte and joint space narrowing) and C-reactive protein (CRP) levels, representing inflammation, were assessed. Groups were compared using nonparametric tests.

RESULTS

The prevalence of anti-CarP was low and not significantly different between the total HOA group and HC (6.6% vs 3.6%, p = 0.12). In HOSTAS, the prevalence of all tested autoantibodies was low (anti-CarP 7.1%, ACPA 0.8%, RF 6.1%), and there were no significant differences observed between HOA patients and HC or between erosive and nonerosive HOA. Further, radiographic damage and CRP levels were similar in anti-CarP+ and anti-CarP-, and RF+ and RF- HOSTAS patients.

CONCLUSION

The prevalence of autoantibodies is similar in HOA patients and HC, and these autoantibodies are not associated with erosive disease, structural damage, or inflammation in patients with HOA, indicating that another mechanism is driving erosive disease.

Ginsenoside Rg3 Attenuates Lipopolysaccharide-Induced Acute Lung Injury via MerTK-Dependent Activation of the PI3K/AKT/mTOR Pathway

Acute lung injury (ALI) is a common clinical disease with high morbidity in both humans and animals. Ginsenoside Rg3, a type of traditional Chinese medicine extracted from ginseng, is widely used to cure many inflammation-related diseases. However, the specific molecular mechanism of the effects of ginsenoside Rg3 on inflammation has rarely been reported. Thus, we established a mouse model of lipopolysaccharide (LPS)-induced ALI to investigate the immune protective effects of ginsenoside Rg3 and explore its molecular mechanism. In wild type (WT) mice, we found that ginsenoside Rg3 treatment significantly mitigated pathological damages and reduced myeloperoxidase (MPO) activity as well as the production of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6); furthermore, the production of anti-inflammatory mediators interleukin-10 (IL-10) and transforming growth factor-β (TGF-β), polarization of M2 macrophages and expression levels of the phosphorylation of phosphatidylinositol 3-hydroxy kinase (PI3K), protein kinase B (PKB, also known as AKT), mammalian target of rapamycin (mTOR) and Mer receptor tyrosine kinase (MerTK) were promoted. However, there were no significant differences with regards to the pathological damage, MPO levels, inflammatory cytokine levels, and protein expression levels of the phosphorylation of PI3K, AKT and mTOR between the LPS treatment group and ginsenoside Rg3 group in MerTK^-/- mice. Taken together, the present study demonstrated that ginsenoside Rg3 could attenuate LPS-induced ALI by decreasing the levels of pro-inflammatory mediators and increasing the production of anti-inflammatory cytokines. These processes were mediated through MerTK-dependent activation of its downstream the PI3K/AKT/mTOR pathway. These findings identified a new site of the specific anti-inflammatory mechanism of ginsenoside Rg3.

Carbamylated albumin is one of the target antigens of anti-carbamylated protein antibodies

Objectives. Anti-carbamylated protein (anti-CarP) antibodies are detected in RA patients. Fetal calf serum is used as an antigen source in anti-CarP ELISA, and the precise target antigens have not been found. We aimed to identify the target antigens of anti-CarP antibodies.

Methods. Western blotting of anti-CarP antibodies was conducted. Anti-carbamylated human albumin (CarALB) antibody was detected by in-house ELISA for 493 RA patients and 144 healthy controls (HCs). An inhibition ELISA of anti-CarP antibodies by CarALB and citrullinated albumin (citALB) was performed using eight RA patients’ sera. Serum CarALB was detected by liquid chromatography–tandem mass spectroscopy (LC/MS/MS), and the serum MPO concentration was measured by ELISA.

Results. We focused on carbamylated albumin because it corresponded to the size of the thickest band detected by western blotting of anti-CarP antibodies. Anti-CarALB antibody was detected in 31.4% of RA patients, and the correlation of the titres between anti-CarALB and anti-CarP was much closer than that between anti-citALB and anti-CCP antibodies (ρ = 0.59 and ρ = 0.16, respectively). The inhibition ELISA showed that anti-CarP antibodies were inhibited by CarALB, but not by citALB. CarALB was detected in sera from RA patients by LC/MS/MS. The serum MPO concentration was correlated with disease activity and was higher in RA patients with anti-CarALB antibody than in those without.

Conclusion. We found that carbamylated albumin is a novel target antigen of anti-CarP antibodies, and it is the first reported target antigen that has not been reported as the target of ACPA.

An emerging role for neutrophil extracellular traps in noninfectious disease

The production of neutrophil extracellular traps (NETs) is a process that enables neutrophils to help catch and kill bacteria. However, increasing evidence suggests that this process might also occur in noninfectious, sterile inflammation. In this Review, we describe the role of NETosis in autoimmunity, coagulation, acute injuries and cancer, and discuss NETs as potential therapeutic targets. Furthermore, we consider whether extracellular DNA is always detrimental in sterile inflammation and whether the source is always NETs.

Chlorinated Phospholipids and Fatty Acids: (Patho)physiological Relevance, Potential Toxicity, and Analysis of Lipid Chlorohydrins

Chlorinated phospholipids are formed by the reaction of hypochlorous acid (HOCl), generated by the enzyme myeloperoxidase under inflammatory conditions, and the unsaturated fatty acyl residues or the head group. In the first case the generated chlorohydrins are both proinflammatory and cytotoxic, thus having a significant impact on the structures of biomembranes. The latter case leads to chloramines, the properties of which are by far less well understood. Since HOCl is also widely used as a disinfecting and antibacterial agent in medicinal, industrial, and domestic applications, it may represent an additional source of danger in the case of abuse or mishandling. This review discusses the reaction behavior of in vivo generated HOCl and biomolecules like DNA, proteins, and carbohydrates but will focus on phospholipids. Not only the beneficial and pathological (toxic) effects of chlorinated lipids but also the importance of these chlorinated species is discussed. Some selected cleavage products of (chlorinated) phospholipids and plasmalogens such as lysophospholipids, (chlorinated) free fatty acids and α-chloro fatty aldehydes, which are all well known to massively contribute to inflammatory diseases associated with oxidative stress, will be also discussed. Finally, common analytical methods to study these compounds will be reviewed with focus on mass spectrometric techniques.

The role of neutrophils in the pathogenesis of systemic lupus erythematosus

PURPOSE OF REVIEW

Recent discoveries implicate neutrophils as important regulators of innate and adaptive immunity and in the development of organ damage in systemic autoimmune diseases, including systemic lupus erythematosus (SLE).

RECENT FINDINGS

Various putative SLE biomarkers are neutrophil-related, including neutrophil granular proteins and histones undergoing post-translational modifications during neutrophil extracellular trap (NET) formation. In the bone marrow, lupus neutrophils can drive B and T cell abnormalities, at least in part, by their enhanced production of type-I interferons, tumor necrosis factor-alpha (TNFα) and the B-cell stimulating factors B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL). Lupus neutrophils and, in particular, lupus low-density granulocytes (a distinct pathogenic subset) display epigenetic modifications and genomic alterations that may be relevant to their deleterious roles in SLE. Proteins and enzymes externalized by lupus NETs can affect vascular health by inducing endothelial apoptosis and oxidizing lipoproteins. Hampering NET formation through peptidylarginine deiminase inhibitors abrogates lupus phenotype and atherosclerosis in murine studies.

SUMMARY

Recent discoveries support the notion that neutrophils, low-density granulocytes and aberrant NET formation and clearance play important roles in lupus pathogenesis. Future studies should focus on how to selectively target these immunostimulatory pathways in this disease.

Oxidative Stress Relevance in the Pathogenesis of the Rheumatoid Arthritis: A Systematic Review

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease whose pathogenic mechanisms remain to be elucidated. The oxidative stress and antioxidants play an important role in the disease process of RA. The study of oxidants and antioxidants biomarkers in RA patients could improve our understanding of disease pathogenesis; likely determining the oxidative stress levels in these patients could prove helpful in assessing disease activity and might also have prognostic implications. To date, the usefulness of oxidative stress biomarkers in RA patients is unclear and the evidence supporting them is heterogeneous. In order to resume and update the information in the status of oxidants and antioxidants and their connection as biomarkers in RA, we performed a systematic literature search in the PubMed database, including clinical trials published in the last five years using the word combination "rheumatoid arthritis oxidative stress". In conclusion, this review supports the fact that the oxidative stress is an active process in RA pathogenesis interrelated to other better known pathogenic elements. However, some controversial results preclude a definite conclusion.

Salivary Concentration of Oxidative Stress Biomarkers in a Group of Patients with Peri-Implantitis: A Transversal Study

PURPOSE

The purpose of this study was to know if peri-implantitis causes an increase in the total salivary concentration of oxidative stress markers.

MATERIALS AND METHODS

Seventy patients, 28 men and 42 women, 60 of them with dental implants, 30 of which had peri-implantitis and 30 were healthy. The remaining 10 were the control group: healthy subjects without implants. The average number of implants per patient was 4.70 ± 2.29 in the peri-implantitis group and 2 70 ± 2.11 in the control group. Periodontal/peri-implant variables were assessed, including bleeding index, gingival index, clinical attachment level, probing depth, presence of pockets larger than 4 and 6 mm, pain to percussion, suppuration, gingival hyperplasia or granuloma, crestal bone loss (both mesially and distally), evaluated through periapical radiography. Saliva samples from the 70 subjects were collected for measurement of malondialdehyde high performance liquid chromatography (HPLC) and myeloperoxidase (enzyme-linked immunosorbent assay analysis) concentrations.

RESULTS

Implants affected with peri-implantitis had an average follow-up of 26.40 ± 7.97 months. 4.12% of implants with peri-implantitis had a painful response to percussion. 2.06% showed suppuration; 25.77% had granuloma. The mean crestal bone loss in implants wtih peri-implantitis was 3.78 ± 1.17 mm. Total salivary malondialdehyde concentration in the peri-implantitis group (0.52 ± 0.37 μM/l) was slightly higher than that in the group with healthy implants (0.40 ± 0.16 μM/l) and also slightly higher than that in the group of healthy patients without implants (0.41 ± 0.79 μM/l), although the difference was not statistically significant, p value = .442. Myeloperoxidase concentration was slightly higher in the peri-implantitis group (12.32 ± 2.17 ng/ml) than in the group with healthy implants (11.54 ± 2.80 ng/ml) and the group of healthy patients without implants (11.86 ± 2.67 ng/ml), without statistically significant differences, p value = .584.

CONCLUSIONS

The salivary concentration of oxidative stress markers in patients with peri-implantitis and without periodontitis is not higher than that found in healthy patients.

Increased carotid artery intima-media thickness and myeloperoxidase level in children with newly diagnosed juvenile idiopathic arthritis

Introduction

Juvenile idiopathic arthritis (JIA) is a frequent childhood rheumatic disease characterized by chronic inflammation. The latter has been related to impairment of arterial functional-structural properties, atherogenesis and later cardiovascular events. The objective of this study was to examine intima-media thickness (IMT) and the parameters of arterial stiffness in children with JIA at diagnosis and their correlation with JIA subtype and markers of inflammation and atherosclerosis.

Methods

Thirty-nine newly diagnosed patients with JIA (26 girls; mean age, 13.2 ± 2.6 years) and 27 healthy controls (9 girls; mean age, 13.6 ± 3.4 years) were included in the study. Twelve patients had oligoarthritis, fifteen had extended oligoarthritis and twelve had rheumatoid factor–negative polyarthritis. IMT of the common carotid artery was determined by ultrasonography, carotid-femoral pulse wave velocity (cfPWV) and augmentation index adjusted to a heart rate of 75 beats/min (AIx@75) were determined by applanation tonometry. The serum levels of atherosclerosis-related biomarkers, such as asymmetric dimethylarginine (ADMA), myeloperoxidase (MPO) and adiponectin, were measured by enzyme-linked immunosorbent assay.

Results

Mean IMT (0.46 ± 0.04 vs. 0.42 ± 0.04 mm; p = 0.0003) and MPO concentration (115.2 [95 % confidence interval {95 % CI}, 97.4–136.3] vs. 57.6 [95 % CI, 47.1–70.3] ng/ml; p < 0.0001) were higher in the patients with JIA than in the control subjects. The cfPWV, AIx@75 and serum ADMA and adiponectin levels did not significantly differ between the groups and JIA subtypes. Serum adiponectin level correlated negatively with AIx@75 in patients with JIA (r = −0.38; p < 0.05).

Conclusions

Patients with JIA have increased mean IMT and elevated MPO levels at early stages of the disease. AIx@75 was inversely independently associated with adiponectin level in the patients, suggesting that lower adiponectin levels might influence arterial subclinical stiffening in patients with newly diagnosed JIA.