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OBJECTIVE: Paraoxonase-1 (PON1) is a high-density lipoprotein (HDL)-associated enzyme, that has been implicated as a biomarker of cardiovascular risk in patients with rheumatoid arthritis (RA). We aimed to investigate how different biologic therapies affect levels of PON1 and oxylipins. METHODS: 1213 adult patients with RA in the Comparative Effectiveness Registry to study Therapies for Arthritis and Inflammatory CoNditions cohort study with moderate-to-high disease activity (Clinical Disease Activity Index (CDAI) >10) who initiated a new biologic (tocilizumab (TCZ), n=296; abatacept, n=374; tumour necrosis factor inhibitors, n=427; rituximab, n=116) were followed prospectively with serum specimens analysed for PON1 activity by arylesterase (ARYL), lactonase (LAC) and PON assays at baseline and after 6 months of biologic therapy. A targeted panel of oxylipins was evaluated by liquid chromatography-mass spectrometry/mass spectrometry in a subset of patients with the lowest and highest 6-month Disease Activity Score 28 (DAS28)-C reactive protein (CRP) responses in each treatment group. RESULTS: PON1 activity generally increased in the entire cohort after 6 months of new biologic therapy, showing the greatest, most consistent increases in the TCZ group. Increases in all three PON1 domains associated with significant decreases in disease activity in DAS28-CRP/CDAI (p

Antibodies to Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) have been reported in pooled healthy donor plasma and intravenous immunoglobulin products (IVIG). It is not known whether administration of IVIG increases circulating anti-SARS-CoV-2 antibodies (COVID ab) in IVIG recipients. COVID ab against the receptor binding domain of the spike protein were analyzed using a chemiluminescent microparticle immunoassay in patients with idiopathic inflammatory myopathies (IIM) both receiving and not receiving IVIG (IVIG and non-IVIG group, respectively). No significant differences in COVID ab levels were noted between IVIG and non-IVIG groups (417 [67-1342] AU/mL in IVIG vs 5086 [43-40,442] AU/mL in non-IVIG, p = 0.11). In linear regression models including all post-vaccination patient samples, higher number of vaccine doses was strongly associated with higher COVID ab levels (2.85 [1.21, 4.48] log AU/mL, regression coefficient [Formula: see text] [95% CI], p = 0.001), while use of RTX was associated with lower ab levels (2.73 [- 4.53, - 0.93] log AU/mL, [Formula: see text][95%CI], p = 0.004). In the IVIG group, higher total monthly doses of IVIG were associated with slightly higher COVID ab levels (0.02 [0.002-0.05] log AU/mL, p = 0.04). While patients on IVIG did not have higher COVID ab levels compared to the non-IVIG group, higher monthly doses of IVIG were associated with higher circulating levels of COVID ab in patients receiving IVIG, particularly in patients concomitantly receiving RTX. Our findings suggest that IIM patients, especially those at increased risk of COVID infection and worse COVID outcomes due to RTX therapy may have protective benefits when on concurrent IVIG treatment.

ObjectivesPatients with idiopathic inflammatory myopathies (IIM) have severe vascular involvement, which contributes to disease morbidity and mortality. Paraoxonase-1 (PON1) is a high-density lipoprotein (HDL) associated protein that protects the vascular endothelium from oxidative injury and damage. The current work assessed the functional and genetic determinants of PON1 activity in IIM patients.MethodsA total of 184 IIM patients and 112 healthy controls (HC) were included. PON1 enzyme activity was assessed by paraoxonase, arylesterase and lactonase assays, and the Q192R PON1 single nucleotide polymorphism (SNP) was analysed. Multivariate regression models examined associations of PON1 activity with IIM diagnosis and myositis disease outcomes.ResultsThe arylesterase and lactonase activities of PON1 were significantly lower in IIM patients compared with HC. Higher myositis disease activity, the presence of severe IIM-associated interstitial lung disease (ILD), and the presence of MDA5 or anti-synthetase antibodies were significantly associated with lower PON1 activity. The PON1 Q192R polymorphism was strongly linked to the paraoxonase activity of PON1 in IIM, and patients with the PON1 QQ genotype had better IIM disease outcomes compared with patients with the QR or RR genotypes.ConclusionsThe arylesterase and lactonase activities of PON1 are significantly impaired in IIM patients compared with HC, and inversely associate with IIM disease activity and the presence of severe ILD. The PON1 QQ genotype associates with more favourable disease outcomes in IIM patients. Large prospective studies are needed to further evaluate the role of PON1 and PON1 genetic polymorphisms in the development and propagation of IIM and IIM-ILD.

Paraoxonase 1(PON1) is an HDL-associated protein, which metabolizes inflammatory, oxidized lipids associated with atherosclerotic plaque development. Because oxidized lipid mediators have also been implicated in the pathogenesis of rheumatoid arthritis (RA), we evaluated the role of PON1 in murine inflammatory arthritis. K/BxN serum transfer (STIA) or collagen antibody transfer (CAIA) was used for arthritis induction in B6 mice homozygous for the PON1 human transgene [PON1Tg], PON1 knock-out mice [PON1KO], and wild type littermate control mice [WT]. Experiments were also performed in K/BxN mice with chronic arthritis, and in RA patients and healthy controls. Arthritis activity in K/BxN mice was associated with a marked dyslipidemia, lower PON1 activity and higher bioactive lipid mediators (BLM), as well as a dysregulated hepatic lipid gene expression profile. Higher serum PON1 activity correlated with lower BLM and lower arthritis activity in both K/BxN mice and RA patients. Overexpression of the human PON1 transgene was associated with reduced inflammatory arthritis, which correlated strongly with higher circulating PON1 activity, upregulation of the hepatic glutathione pathway, and reduction of circulating BLM. These results implicate PON1 as a potential novel therapeutic target for joint disease in RA with potential for vascular benefit, which warrants further investigation.

The objective of this study was to evaluate oxidation products of arachidonic acid and linoleic acid in lipoproteins and synovial fluid (SF) from patients with active rheumatoid arthritis (RA) compared to non-RA controls. High-density lipoproteins (HDL) and low-density lipoproteins (LDL) were isolated from plasma using fast protein liquid chromatography and HDL was isolated from SF using dextran sulfate precipitation. 5-Hydroxyeicosatetraenoic acid (HETE), 12-HETE, 15-HETE, 9 hydroxyoctadecadienoic (HODE), and 13-HODE levels were measured in HDL, LDL, and SF by liquid chromatography-tandem mass spectrometry. HDL's anti-inflammatory function, cholesterol levels, myeloperoxidase (MPO) and paraoxonase 1 (PON1) activities were determined as previously. 5-HETE, 15-HETE, 9-HODE, and 13-HODE levels were significantly increased in HDL and LDL from patients with active RA (n = 10) compared to healthy controls (n = 8) and correlated significantly with measures of systemic inflammation, particularly in HDL (r = 0.65-0.80, p values

ObjectiveAbnormal function of high-density lipoprotein (HDL) has been implicated as a potential mechanism for the increased incidence of cardiovascular (CV) disease in patients with rheumatoid arthritis (RA). This study was undertaken to evaluate changes in HDL function and HDL-associated proteins over 2 years of follow-up in patients with early RA receiving either methotrexate (MTX) monotherapy, MTX + etanercept (ETN) combination therapy, or MTX + sulfasalazine (SSZ) + hydroxychloroquine (HCQ) triple therapy in the Treatment of Early Aggressive Rheumatoid Arthritis (TEAR) trial.MethodsThe antioxidant capacity of HDL, paraoxonase 1 (PON-1) activity, and levels of HDL-associated haptoglobin (Hp), HDL-associated apolipoprotein A-I (Apo A-I), and myeloperoxidase (MPO) were measured in 550 TEAR participants at 4 time points (time 0 [pretreatment] and at 24, 48, and 102 weeks of treatment). Repeated-measures analysis using mixed-effects linear models with an autoregressive covariate structure was performed to model the within-subject covariance over time.ResultsMixed-effects models, which were controlled for traditional CV risk factors, treatment regimen, prednisone use, and statin use, demonstrated significant associations between RA disease activity, measured using the Disease Activity Score in 28 joints, erythrocyte sedimentation rate, or C-reactive protein level, and the profile of HDL function over time. Specifically, decreases in RA disease activity over time were associated with increases in PON-1 activity and levels of HDL-associated Apo A-I, and decreases in the HDL inflammatory index and levels of MPO and HDL-associated Hp.ConclusionReduced disease activity in patients with early RA treated with MTX monotherapy, MTX + ETN combination therapy, or MTX + SSZ + HCQ triple therapy in the TEAR trial was associated with improvements in the HDL function profile. Additional studies are warranted to evaluate abnormal HDL function as a potential mechanism and therapeutic target for CV risk in patients with RA.

ObjectiveTo investigate the relationship of genetic and biochemical determinants of paraoxonase 1 activity to carotid plaque as a surrogate marker of cardiovascular (CV) risk in patients with rheumatoid arthritis (RA).MethodsThe relationships between paraoxonase 1 activity, PON1 genotype (for the functional polymorphism at position 192), and carotid plaque presence were determined in 168 RA patients. After an overnight fast, blood was collected for lipoprotein analysis, and paraoxonase 1 activity was measured using paraoxon as the substrate. The PON1 Q192R genotype was determined for all patients. Lipoprotein cholesterol levels, traditional CV risk factors, medication use, and RA disease characteristics were assessed for all patients.ResultsParaoxonase 1 activity values in the RA patients were highest for the RR genotype, intermediate for the QR genotype, and lowest for the QQ genotype (P < 0.0001). Compared to patients with either the QQ genotype or the QR genotype, patients with the RR genotype demonstrated decreased risk of carotid plaque on multivariate analysis, controlling for traditional CV risk factors, high-sensitivity C-reactive protein levels, prednisone use, and cholesterol-lowering medication use (P < 0.05). Additional multivariate logistic regression analysis controlling for the above factors also revealed a significant association of plasma paraoxonase 1 activity with carotid plaque in RA patients. Lower plasma paraoxonase 1 activity was associated with increased risk of carotid plaque (P < 0.05).ConclusionThe current findings suggest a relationship of the genetic determinants and activity of paraoxonase 1 to CV risk in RA patients, as assessed by the presence or absence of carotid plaque. Further CV outcome studies are warranted to validate the utility of paraoxonase 1 as a biomarker of CV risk in patients with RA.

Cyclooxygenase-2 (COX-2) is an important regulator of inflammation implicated in the development of a variety of diseases, including inflammatory bowel disease (IBD). However, the regulation of intestinal inflammation by COX-2 is poorly understood. We previously reported that COX-[2.sup.-/-] mice fed a cholate-containing high-fat (CCHF) diet had high mortality of unknown mechanisms attributable to severe intestinal inflammation in the ileo-ceco-colic junction that presented characteristics similar to Crohn's disease (CD). To further characterize the role of COX-2 in intestinal inflammation, we established cell-specific conditional COX-[2.sup.-/-] mice. Endothelial cell-specific (COX-[2.sup.-E/-E]) and myeloid cell-specific (COX-[2.sup.-M/-M]) COX-[2.sup.-/-] mice, but not wild-type mice, on the CCHF diet developed localized CD-like pathology at the ileo-ceco-colic junction that was associated with cellular infiltration, increased expression of myeloperoxidase and IL-5, and decreased IL-10 expression. The CD-like pathology in COX-[2.sup.-E/-E] mice was also accompanied by increased expression of cytokines (IL-6, TNF-[alpha], and INF-[gamma]), compared with wild-type mice and COX-[2.sup.-M/-M] mice. In contrast, the ileo-ceco-colic inflammation in COX-[2.sup.-M/-M] mice was associated with more pronounced infiltration of granulocytes and macrophages than COX-[2.sup.-E/-E] mice. COX-[2.sup.-ME/-ME] (COX-[2.sup.-M/-M] x COX-[2.sup.-E/-E]) mice on the CCHF diet developed CD-like pathology in the ileo-ceco-colic junction reminiscent of total COX-[2.sup.-/-] mice on CCHF diet and wild-type mice on CCHF diet treated with COX-2 inhibitor, celecoxib. The pathology of diet-mediated ileo-ceco-colic inflammation in COX-[2.sup.-/-] mice offers an excellent model system to elucidate the protective roles of endothelial and myeloid COX-2 and the molecular pathogenesis of CD. ileo-ceco-colic junction; inflammation doi: 10.1152/ajpgi.00468.2009.

The article discusses a study which showed that proline (Pro) 64 is important for binding and inhibition of bone morphogenetic protein (BMP)-4 but not for binding calcium. To modify Pro64 and the glutamates (Gla) residues, and the effect on BMP-4 activity, site-directed mutagenesis was used in the study. Binding of BMP-4 and calcium was tested using luciferase reporter gene assays, communoprecipitation, crosslinking, and calcium quantification. The results suggest that BMP and calcium binding in MGP are independent but intertwined processes.

Arterial calcification is ubiquitous in vascular disease and is, in part, prevented by matrix Gla protein (MGP). MGP binds calcium ions through gamma-carboxylated glutamates (Gla residues) and inhibits bone morphogenetic protein (BMP)-2/-4. We hypothesized that a conserved proline (Pro)64 is essential for BMP inhibition. We further hypothesized that calcium binding by the Gla residues is a prerequisite for BMP inhibition. Site-directed mutagenesis was used to modify Pro64 and the Gla residues, and the effect on BMP-4 activity, and binding of BMP-4 and calcium was tested using luciferase reporter gene assays, coimmunoprecipitation, crosslinking, and calcium quantification. The results showed that Pro64 was critical for binding and inhibition of BMP-4 but not for calcium binding. The Gla residues were also required for BMP-4 binding but flexibility existed. As long as 1 Gla residue remained on each side of Pro64, the ability to bind and inhibit BMP-4 was preserved. Chelation of calcium ions by EDTA or warfarin treatment of cells led to loss of ability of MGP to bind BMP-4. Our results also showed that phenylalanine could replace Pro64 without loss of function and that zebrafish MGP, which lacks upstream Gla residues, did not function as a BMP inhibitor. The effect of MGP mutagenesis on vascular calcification was determined in calcifying vascular cells. Only MGP proteins with preserved ability to bind and inhibit BMP-4 prevented osteogenic differentiation and calcification. Together, our results suggest that BMP and calcium binding in MGP are independent but functionally intertwined processes and that the BMP binding is essential for prevention of vascular calcification.