The PTPN22 gene is associated with idiopathic inflammatory myopathy.

INTRODUCTION: The aim of this study was to determine whether a single-nucleotide polymorphism (SNP; 1858CT, R620W) in the protein tyrosine phosphatase N22 (PTPN22) gene confers susceptibility to idiopathic inflammatory myopathy (IIM) in South Australian patients with IIM. METHODS: Genotyping was performed on stored DNA from 199 patients with histologically confirmed polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM), and then compared with 455 matched controls. Associations with the 8.1 ancestral haplotype (AH), and myositis-specific (MSA) and myositis-associated (MAA) autoantibodies were investigated. RESULTS: The PTPN22 R620W minor allele frequency was increased in IIM patients (50 of 398, 12.6%) compared with controls (75 of 910, 8.2%) (odds ratio 1.6, 95% confidence interval 1.1-2.3, P = 0.016). In IIM patients, there was no association between the R620W minor allele and detection of any MSA/MAA (P = 0.70), nor any evidence of epistasis with the 8.1 AH (P = 0.69). CONCLUSIONS: The PTPN22 R620W minor allele is associated with susceptibility to IIM in SA patients, independent of the 8.1 AH. Muscle Nerve, 2016 Muscle Nerve 55: 270-273, 2017.

Fish oil in knee osteoarthritis: a randomised clinical trial of low dose versus high dose.

OBJECTIVES: To determine whether high-dose fish oil is superior to low-dose supplementation for symptomatic and structural outcomes in knee osteoarthritis (OA). METHODS: A randomised, double-blind, multicentre trial enrolled 202 patients with knee OA and regular knee pain. They were randomised 1:1 to high-dose fish oil (4.5 g omega-3 fatty acids) 15 mL/day or (2) low-dose fish oil (blend of fish oil and sunola oil; ratio of 1:9, 0.45 g omega-3 fatty acids) 15 mL/day. The primary endpoints were Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score at 3, 6, 12 and 24 months, and change in cartilage volume at 24 months. Secondary outcomes included WOMAC function, quality of life, analgesic and non-steroidal anti-inflammatory drug use and bone marrow lesion score. RESULTS: Although there was improvement in both groups, the low-dose fish oil group had greater improvement in WOMAC pain and function scores at 2 years compared with the high-dose group, whereas between-group differences at 1 year did not reach statistical significance. There was no difference between the two groups in cartilage volume loss at 2 years. For other secondary endpoints, there was no difference between the two groups at 2 years. CONCLUSIONS: In people with symptomatic knee OA, there was no additional benefit of a high-dose fish oil compared with low-dose fish oil. The combination comparator oil appeared to have better efficacy in reducing pain at 2 years, suggesting that this requires further investigation. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN 12607000415404).

Ten years of publicly funded biological disease-modifying antirheumatic drugs in Australia.

Biological disease-modifying antirheumatic drugs (bDMARDs) for rheumatoid arthritis (RA) treatment were among the first high-cost medicines to be subsidised in Australia. High-cost medicines pose several challenges to the Australian National Medicines Policy, which aims to provide timely access to effective medicines at a cost individuals and the community can afford. Thus, novel restriction criteria were developed to encourage cost-effective use of bDMARDs. Government expenditure on bDMARD subsidies for RA treatment grew to about $383 million in 2014. Evidence that initiation and continuation criteria for bDMARDs meet usually applied cost-benefit criteria is lacking. The combined expenditure on tocilizumab, certolizumab pegol and golimumab (added to the Australian Government's Pharmaceutical Benefits Scheme in 2010) was $93 million in 2014, which is 210% over the initial estimate. Present and future challenges with regard to bDMARDs for RA and other high-cost drugs include improved expenditure predictions, monitoring of cost-effectiveness in relation to actual use and strategic development, regulation and use of biosimilars. Ten years of documentation on clinical and laboratory findings indicating eligibility to initiate and continue on bDMARDs remains un-used. These data represent an untapped opportunity to promote quality of use of bDMARDs and biosimilars and to improve cost predictions for high-cost drugs.

Fish oil in recent onset rheumatoid arthritis: a randomised, double-blind controlled trial within algorithm-based drug use.

BACKGROUND: The effects of fish oil (FO) in rheumatoid arthritis (RA) have not been examined in the context of contemporary treatment of early RA. This study examined the effects of high versus low dose FO in early RA employing a 'treat-to-target' protocol of combination disease-modifying anti-rheumatic drugs (DMARDs). METHODS: Patients with RA <12 months' duration and who were DMARD-naïve were enrolled and randomised 2:1 to FO at a high dose or low dose (for masking). These groups, designated FO and control, were given 5.5 or 0.4 g/day, respectively, of the omega-3 fats, eicosapentaenoic acid + docosahexaenoic acid. All patients received methotrexate (MTX), sulphasalazine and hydroxychloroquine, and DMARD doses were adjusted according to an algorithm taking disease activity and toxicity into account. DAS28-erythrocyte sedimentation rate, modified Health Assessment Questionnaire (mHAQ) and remission were assessed three monthly. The primary outcome measure was failure of triple DMARD therapy. RESULTS: In the FO group, failure of triple DMARD therapy was lower (HR=0.28 (95% CI 0.12 to 0.63; p=0.002) unadjusted and 0.24 (95% CI 0.10 to 0.54; p=0.0006) following adjustment for smoking history, shared epitope and baseline anti-cyclic citrullinated peptide. The rate of first American College of Rheumatology (ACR) remission was significantly greater in the FO compared with the control group (HRs=2.17 (95% CI 1.07 to 4.42; p=0.03) unadjusted and 2.09 (95% CI 1.02 to 4.30; p=0.04) adjusted). There were no differences between groups in MTX dose, DAS28 or mHAQ scores, or adverse events. CONCLUSIONS: FO was associated with benefits additional to those achieved by combination 'treat-to-target' DMARDs with similar MTX use. These included reduced triple DMARD failure and a higher rate of ACR remission.

Plasma n-3 fatty acids and clinical outcomes in recent-onset rheumatoid arthritis.

A randomised controlled trial (RCT) of high-dose v. low-dose fish oil in recent-onset rheumatoid arthritis (RA) demonstrated that the group allocated to high-dose fish oil had increased remission and decreased failure of disease-modifying anti-rheumatic drug (DMARD) therapy. This study examines the relationships between plasma phospholipid levels of the n-3 fatty acids in fish oil, EPA and DHA, and remission and DMARD use in recent-onset RA. EPA and DHA were measured in blood samples from both groups of the RCT. The data were analysed as a single cohort, and Cox proportional hazards models were used to examine relationships between plasma phospholipid (PL) EPA and DHA and various outcome measures. When analysed as a single cohort, plasma PL EPA was related to time to remission, with a one unit increase in EPA (1% total fatty acids) associated with a 12% increase in the probability of remission at any time during the study period (hazard ratio (HR)=1.12; 95% CI 1.02, 1.23; P=0.02). Adjustment for smoking, anti-cyclic citrullinated peptide antibodies and 'shared epitope' HLA-DR allele status did not change the HR. Plasma PL EPA, adjusted for the same variables, was negatively related to time to DMARD failure (HR=0.85; 95% CI 0.72, 0.99; P=0.047). The HR for DHA and time to remission or DMARD failure were similar in magnitude to those for EPA, but not statistically significant. Biomarkers of n-3 status, such as plasma PL EPA, have the potential to predict clinical outcomes relevant to standard drug treatment of RA patients.

Pitfalls in the use of randomised controlled trials for fish oil studies with cardiac patients.

Randomised controlled trials (RCT) examining the effects of fish oil supplementation on cardiac outcomes have yielded varying results over time. Although RCT are placed at the top of the evidence hierarchy, this methodology arose in the framework of pharmaceutical development. RCT with pharmaceuticals differ in important ways from RCT involving fish oil interventions. In particular, in pharmaceutical RCT, the test agent is present only in the intervention group and not in the control group, whereas in fish oil RCT, n-3 fats are present in the diet and in the tissues of both groups. Also, early phase studies with pharmaceuticals determine pharmacokinetics and pharmacodynamics to design the dose of the RCT intervention so that it is in a predicted linear dose-response range. None of this happens in fish oil RCT, and there is evidence that both baseline n-3 intake and tissue levels may be sufficiently high in the dose-response range that it is not possible to demonstrate a clinical effect with a RCT. When these issues are considered, it is possible that the changing pattern of fish consumption and fish oil use over time, especially in cardiac patients, can explain the disparity where benefit was observed in the early fish oil trials but not in the more recent trials.

Appendicular skeletal muscle in hospitalised hip-fracture patients: development and cross-validation of anthropometric prediction equations against dual-energy X-ray absorptiometry.

BACKGROUND: accurate and practical assessment methods for assessing appendicular skeletal muscle (ASM) is of clinical importance for the diagnosis of geriatric syndromes associated with skeletal muscle wasting. OBJECTIVES: the purpose of this study was to develop and cross-validate novel anthropometric prediction equations for the estimate of ASM in older adults post-surgical fixation for hip fracture, using dual-energy X-ray absorptiometry (DEXA) as the criterion measure. SUBJECTS: community-dwelling older adults (aged ≥65 years) recently hospitalised for hip fracture. SETTING: participants were recruited from hospital in the acute phase of recovery. DESIGN: validation measurement study. MEASUREMENTS: a total of 79 hip fracture patients were involved in the development of the regression models (MD group). A further 64 hip fracture patients also recruited in the early phase of recovery were used in the cross-validation of the regression models (CV group). Multiple linear regression analyses were undertaken in the MD group to identify the best performing prediction models. The linear coefficient of determination (R(2)) in addition to the standard error of the estimate (SEE) were calculated to determine the best performing model. Agreement between estimated ASM and ASMDEXA in the CV group was assessed using paired t-tests with the 95% limits of agreement (LOA) assessed using Bland-Altman analyses. RESULTS: the mean age of all the participants was 82.1 ± 7.3 years. The best two prediction models are presented as follows: ASMPRED-EQUATION_1: 22.28 - (0.069 * age) + (0.407 * weight) - (0.807 * BMI) - (0.222 * MAC) (adjusted R(2): 0.76; SEE: 1.80 kg); ASMPRED-EQUATION_2: 16.77 - (0.036 * age) + (0.385 * weight) - (0.873 * BMI) (adjusted R(2): 0.73; SEE: 1.90 kg). The mean bias from the CV group between ASMDEXA and the predictive equations is as follows: ASMDEXA - ASMPRED-EQUATION_1: 0.29 ± 2.6 kg (LOA: -4.80, 5.40 kg); ASMDEXA - ASMPRED-EQUATION_2: 0.13 ± 2.5 kg (LOA: -4.77, 5.0 kg). No significant difference was observed between measured ASMDEXA and estimated ASM (ASMDEXA: 16.4 ± 3.9 kg; ASMPRED-EQUATION_1: 16.7 ± 3.2 kg (P = 0.379); ASMPRED-EQUATION_2: 16.6 ± 3.2 kg (P = 0.670)). CONCLUSIONS: we have developed and cross-validated novel anthropometric prediction equations against DEXA for the estimate of ASM designed for application in older orthopaedic patients. Our equation may be of use as an alternative to DEXA in the diagnosis of skeletal muscle wasting syndromes. Further validation studies are required to determine the clinical utility of our equation across other settings, including hip fracture patients admitted from residential care, and also with a longer-term follow-up.

Molecular basis for differential elongation of omega-3 docosapentaenoic acid by the rat Elovl5 and Elovl2.

Functional characterization of the rat elongases, Elovl5 and Elovl2, has identified that Elovl2 is crucial for omega-3 docosahexaenoic acid (DHA) (22:6n-3) synthesis. While the substrate specificities of the rat elongases had some overlap, only Elovl2 can convert the C22 omega-3 PUFA docosapentaenoic acid (DPA) (22:5n-3) to 24:5n-3, which is the penultimate precursor of DHA. In order to better understand the potential for these elongases to be involved in DHA synthesis, we have examined the molecular reasons for the differences between Elovl5 and Elovl2 in their ability to elongate DPA to 24:5n-3. We identified a region of heterogeneity between Elovl5 and Elovl2 spanning transmembrane domains 6 and 7. Using a yeast expression system, we examined a series of Elovl2/Elovl5 chimeras and point mutations to identify Elovl2 residues within this region which are responsible for DPA substrate specificity. The results indicate that the cysteine at position 217 in Elovl2 and a tryptophan at the equivalent position in Elovl5 explain their differing abilities to elongate DPA to 24:5n-3. Further studies confirmed that Elovl2 C217 is a critical residue for elongation of DPA at the level observed in the native protein. Understanding the ability of elongases to synthesize 24:5n-3 may provide a basis for using sequence data to predict their ability to ultimately support DHA synthesis.

Active foot synovitis in patients with rheumatoid arthritis: applying clinical criteria for disease activity and remission may result in underestimation of foot joint involvement.

OBJECTIVE: To determine whether application of criteria for remission in rheumatoid arthritis (RA) may result in underestimation of foot joint involvement among patients in a clinic setting. METHODS: RA patients (n = 123) were assessed at baseline and 6 months after commencement of a response-driven combination disease-modifying antirheumatic drug (DMARD) protocol. Remission was assessed using disease activity measures (the 28-joint Disease Activity Score using the erythrocyte sedimentation rate [DAS28-ESR], Simplified Disease Activity Index [SDAI], and Clinical Disease Activity Index [CDAI]) as well as Boolean-based criteria for remission (the 1981 American College of Rheumatology [ACR] preliminary criteria and the 2011 ACR/European League Against Rheumatism [EULAR] provisional criteria). The prevalence of foot synovitis and the mean swollen/tender foot joint count in RA patients meeting any of these remission criteria were estimated by hurdle (mixed distribution) regression. RESULTS: In patients who received 6 months of combination DMARD treatment, application of the 1981 ACR criteria and the newly proposed 2011 ACR/EULAR criteria, each utilizing full joint counts (which includes assessment of the feet), classified the least number of patients as being in remission (8-10%), and evidence of foot synovitis was minimal among these patients. In contrast, ongoing foot synovitis was present in a substantial proportion of patients (>20%) meeting the 28-joint count criteria for remission, including the DAS28-ESR, SDAI, CDAI, and 2011 ACR/EULAR criteria (clinical practice setting or clinical trials). Furthermore, applying the 2011 ACR/EULAR composite remission criterion of a SDAI score ≤3.3 to define remission did not adequately capture the resolution of foot synovitis (i.e., residual foot involvement was still detected in a substantial proportion of patients classified as being in remission by this definition). CONCLUSION: Although the DAS28-ESR, CDAI, and SDAI have been validated for assessment of remission in RA, this study shows that the performance of these 3 disease activity measures, which do not provide a direct assessment of the foot, in detecting foot synovitis is poor, in contrast to that of the 1981 ACR and 2011 ACR/EULAR remission criteria utilizing full joint counts. Thus, patients may be at risk of ongoing damage if treatment decisions are made solely on the basis of criteria that omit foot joint assessment.

Fish oil administration in older adults: is there potential for adverse events? A systematic review of the literature.

BACKGROUND: Omega-3 (n-3) fatty acid supplementation is becoming increasingly popular. However given its antithrombotic properties the potential for severe adverse events (SAE) such as bleeding has safety implications, particularly in an older adult population. A systematic review of randomized control trials (RCT) was conducted to explore the potential for SAE and non-severe adverse events (non-SAE) associated with n-3 supplementation in older adults. METHODS: A comprehensive search strategy using Medline and a variety of other electronic sources was conducted. Studies investigating the oral administration of n-3 fish oil containing eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or both against a placebo were sourced. The primary outcome of interest included reported SAE associated with n-3 supplementation. Chi-square analyses were conducted on the pooled aggregate of AEs. RESULTS: Of the 398 citations initially retrieved, a total of 10 studies involving 994 older adults aged ≥60 years were included in the review. Daily fish oil doses ranged from 0.03 g to 1.86 g EPA and/or DHA with study durations ranging from 6 to 52 weeks. No SAE were reported and there were no significant differences in the total AE rate between groups (n-3 intervention group: 53/540; 9.8%; placebo group: 28/454; 6.2%; p = 0.07). Non-SAE relating to gastrointestinal (GI) disturbances were the most commonly reported however there was no significant increase in the proportion of GI disturbances reported in participants randomized to the n-3 intervention (n-3 intervention group: 42/540 (7.8%); placebo group: 24/454 (5.3%); p = 0.18). CONCLUSIONS: The potential for AEs appear mild-moderate at worst and are unlikely to be of clinical significance. The use of n-3 fatty acids and the potential for SAE should however be further researched to investigate whether this evidence is consistent at higher doses and in other populations. These results also highlight that well-documented data outlining the potential for SAE following n-3 supplementation are limited nor adequately reported to draw definitive conclusions concerning the safety associated with n-3 supplementation. A more rigorous and systematic approach for monitoring and recording AE data in clinical settings that involve n-3 supplementation is required.

Prostaglandin D(2) in inflammatory arthritis and its relation with synovial fluid dendritic cells.

Prostaglandin (PG)D2 has been shown to be an active agent in the resolution of experimentally induced inflammation. This study was undertaken to determine the presence of PGD2 in chronic joint effusions and to explore the potential contributions of dendritic cells (DC) and monocytes to the intra-articular synthesis of PGD2. Synovial fluid (SF) was obtained from patients with inflammatory arthritis and knee effusions. PGD2 and PGE2 were detected in SF by ultrahigh-performance tandem mass spectrometry. Cellular fractions in SF were separated by density-gradient centrifugation and flow cytometry. The expression of hematopoietic prostaglandin D-synthase (hPGDS) and PGE-synthase (PGES) mRNA was determined by RT-PCR. Both PGD2 and PGE2 were detected in blood and SF, with PGD2 being more abundant than PGE2 in SF. mRNA for hPGDS was more abundant in SF mDCs than SF monocytes (P < 0.01) or PB monocytes (P < 0.001). SF mDC expressed significantly more hPGDS than PGES. Expressions of PGD2 and hPGDS were inversely associated with serum C-reactive protein (P < 0.01) and erythrocyte sedimentation rate (P < 0.01). The findings suggest that synovial DCs may be an important source of hPGDS and that systemic disease activity may be influenced by actions of PGD2 in RA and other arthropathies.

Efficacy and mechanisms of action of vitamin D in experimental polyarthritis.

Vitamin D (vit D) status has been linked to the occurrence and severity of auto-immune and inflammatory diseases. This study evaluates the effects of vit D status on adoptive transfer of adjuvant-induced arthritis (ATA). Rats maintained on diets replete or deficient in vit D3 received arthritogenic thoracic duct cells and were monitored for severity of arthritis. CD45(+) cells obtained by collagenase digestion of hind-paw synovium-rich tissues (SRTs) were analysed to observe the effects of dietary vit D3 on the inflammatory process. Arthritis was more severe in vitamin D-deficient (vit-D(-)) rats compared with vitamin D-replete (vit-D(+)) rats. Resolution was delayed in vit-D(-) rats compared with vit-D(+) rats, or rats fed standard chow. During the acute phase of ATA, numbers of CD45(+) cells were significantly increased in the SRTs of vit-D(-) rats compared with vit-D(+) rats. This increase involved T-cells, polymorphonuclear leukocytes, macrophages, dendritic cells (DCs) and MHC II(hi) cells that resemble activated monocytes. A major difference between the dietary groups was that most DCs at the peak of inflammation in vit-D(-) rats were CD4(-), whereas in convalescent vit-D(+) rats most expressed CD4. Multiple categories of genes expressed by DCs differed between deficient and replete rats, with deficiency being associated with relative upregulation of certain pro-inflammatory genes and replete status being associated with upregulation of genes associated with resolution of inflammation. The findings indicate that ATA is more severe and prolonged in vit-D deficiency, that vit-D deficiency promotes accumulation of CD4(-) DCs in synovium during ATA and that a gene-expression profile is likely to contribute to the observed increased severity and duration of arthritis.

Precision Medicine With Leflunomide: Consideration of the DHODH Haplotype and Plasma Teriflunomide Concentration and Modification of Outcomes in Patients With Rheumatoid Arthritis.

OBJECTIVE: Leflunomide is a commonly used disease-modifying drug in the treatment of rheumatoid arthritis (RA). Its effects are mediated via inhibition of dihydroorotate dehydrogenase (DHODH) by its active metabolite teriflunomide, and the pharmacokinetics of teriflunomide are highly variable. Our objective was to examine the association between the DHODH haplotype and plasma teriflunomide concentration with response to leflunomide in patients with RA where leflunomide was added to an existing disease-modifying drug regimen after failure to achieve an adequate response with conventional triple therapy. METHODS: Patients with RA who were taking, or were about to initiate, leflunomide were included. Participant characteristics, including the DHODH haplotype, were determined. Up to 5 plasma samples were collected after leflunomide was initiated for assays of total and free teriflunomide concentration. Disease activity was determined via the 28-joint Disease Activity Score (DAS28). The association between DAS28 scores and patient covariates was determined by linear mixed-effects modeling. RESULTS: A total of 67 patients were included in the study. The DAS28 score after initiation of leflunomide was associated with the baseline DAS28 score (ß = 0.70, P < 0.001) and was higher in those who carried the DHODH haplotype 2 (ß = 0.56. P = 0.01) and did not carry the shared epitope (ß = 0.56, P = 0.013). As total and free plasma teriflunomide concentration increased, the DAS28 score was significantly lower (P < 0.001 and P = 0.001, respectively). When considering threshold concentrations, teriflunomide concentrations >16 mg/liter were associated with a DAS28 score that was 0.33 lower, and when free teriflunomide concentration was >35 µg/liter, the DAS28 score was 0.32 lower. CONCLUSION: Teriflunomide concentration and carriage of the DHODH haplotype 2 are associated with response to leflunomide in patients with RA, and a total plasma teriflunomide concentration of at least 16 mg/liter is needed to maximize the likelihood of response.

Characterization of prostaglandin E2 generation through the cyclooxygenase (COX)-2 pathway in human neutrophils.

In the present study, we characterized the generation of prostaglandin (PG)E2 in human neutrophils. We found that the Ca2+-dependent type IV cytosolic phospholipase A2 (cPLA2) was pivotally involved in the COX-2-mediated generation of PGE2 in response to a calcium ionophore, as determined by the use of selected PLA2 inhibitors. PGE2 biosynthesis elicited by bacterial-derived peptides or by phagocytic stimuli acting on cell surface receptors also showed to be dependent on cPLA2 activity. We then assessed metabolism of unesterified arachidonic acid (AA), and observed that PGE2 production becomes favored over that of LTB4 with higher AA concentrations. Withdrawal of calcium prevented the generation of PGE2 in response to a calcium ionophore but did not affect the up-regulation of COX-2 or its capacity to convert AA, thus limiting its implication at the level of cPLA2 activation. Of the main eicosanoids produced by neutrophils, only LTB4 was able to up-regulate COX-2 expression. Finally, the only PGE synthase isoform found in neutrophils is microsomal PGE synthase-1; it co-localized with COX-2 and its expression appeared mainly constitutive. These results highlight key differences in regulatory processes of the 5-LO and COX pathways, and enhance our knowledge at several levels in the PGE2 biosynthesis in neutrophils.

FAT/CD36 expression alone is insufficient to enhance cellular uptake of oleate.

Fatty acid translocase (FAT/CD36) is one of several proteins implicated in receptor-mediated uptake of long-chain fatty acids (LCFAs). We have tested whether levels of FAT/CD36 correlate with cellular oleic acid import, using a Tet-Off inducible transfected CHO cell line. Consistent with our previous findings, FAT/CD36 was enriched in lipid raft-derived detergent-resistant membranes (DRMs) that also contained caveolin-1, the marker protein of caveolae. Furthermore in transfected cells, plasma membrane FAT/CD36 co-localized extensively with the lipid raft-enriched ganglioside GM1, and partially with a caveolin-1-EGFP fusion protein. Nevertheless, even at high levels of expression, FAT/CD36 did not affect uptake of oleic acid. We propose that the ability of FAT/CD36 to mediate enhanced uptake of LCFAs is dependent on co-expression of other proteins or factors that are lacking in CHO cells.

Effect of dietary n-3 polyunsaturated fatty acids on the inducibility of ventricular tachycardia in patients with ischemic cardiomyopathy.

Increased consumption of fish and/or fish oil was associated with decreased risk of sudden cardiac death (SCD). The study aim was to evaluate the antiarrhythmic effect of dietary fish oil on the inducibility of ventricular tachycardia (VT) at high risk of SCD. Patients with coronary artery disease undergoing defibrillator implantation were recruited if sustained monomorphic VT could be induced by programmed extra stimuli at 2 cycle lengths. After the initial study, 12 patients consumed 3 g/d of encapsulated fish oil for approximately 6 weeks before a repeated electrophysiologic study. To control for fluctuations in the inducibility of VT, an additional 14 patients with no dietary manipulation were also studied. Aggressiveness of stimulation required to induce VT was ranked from least aggressive to most aggressive based on cycle length and number of extra stimuli, with noninducibility ranked highest. At the repeated electrophysiologic study, in the fish-oil group, 42% had no inducible VT, 42% required more aggressive stimulation to induce VT, 8% required identical stimulation, and 8% required less stimulation compared with 7%, 36%, 36%, and 21% in the control group, respectively. Overall, there was a change to noninducible or less inducible VT in the fish-oil group, but no change in the control group (p = 0.003 and p = 0.65, respectively; Wilcoxon's sign-rank test). In conclusion, dietary n-3 fatty acid supplementation decreased the inducibility of VT in patients at risk of SCD. These findings suggest that dietary fish oil can have an antiarrhythmic effect.

Endothelial cell COX-2 expression and activity in hypoxia.

The clinical experience with selective cyclooxygenase (COX)-2 inhibitors reveals there are important protective roles for COX-2 in the cardiovascular system. This study examined the response to hypoxia of endothelial cell eicosanoid synthesis with respect to the role of COX-2 and its molecular regulation in hypoxia. Human umbilical vein endothelial cells (HUVEC) were exposed to hypoxia and the effects on COX-2, prostacyclin (PGI(2)) and thromboxane (TXA(2)) synthesis were examined. COX-2 promoter constructs were used to examine the role of Hypoxia Inducible Factors (HIFs) in COX-2 responses to hypoxia. Hypoxia caused an increase in PGI(2) synthesis, but not TXA(2) synthesis. PGI(2), but not TXA(2) synthesis, was absolutely dependent on upregulation of COX-2 by hypoxia. Mutations of transcription factor binding sites in the promoter showed a lack of involvement of NFkappaB in the response to hypoxia, but suggested involvement of HIFs. Transfection of HUVEC with HIF expression vectors increased activity of the promoter construct and increased native COX-2 expression in normoxia. EMSA showed HIF binding in nuclear extracts of hypoxic HUVEC to a region of the COX-2 promoter. The endothelial cell response to hypoxia involves increased production of the anti-thrombotic eicosanoid, PGI(2), which is dependent on COX-2 upregulation by a HIF-mediated process.

Effects of fish-oil supplementation on myocardial fatty acids in humans.

BACKGROUND: Increased fish or fish-oil consumption is associated with reduced risk of cardiac mortality, especially sudden death. This benefit putatively arises from the incorporation of the long-chain n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into cardiomyocyte phospholipids. OBJECTIVE: The study examined the kinetics of incorporation of n-3 fatty acids into human myocardial membrane phospholipids during supplementation with fish oil and alpha-linolenic acid-rich flaxseed oil. DESIGN: Patients with low self-reported fish intake (<1 fish meal/wk and no oil supplements) accepted for elective cardiac surgery involving cardiopulmonary bypass were randomly allocated to 1 of 6 groups: no supplement; fish oil (6 g EPA+DHA/d) for either 7, 14, or 21 d before surgery; flaxseed oil; or olive oil (both 10 mL/d for 21 d before surgery). Right atrial appendage tissue removed during surgery and blood collected at enrollment and before surgery were analyzed for phospholipid fatty acids. RESULTS: Surgery rescheduling resulted in a range of treatment times from 7 to 118 d. In the fish-oil-treated subjects, accumulation of EPA and DHA in the right atrium was curvilinear with time and reached a maximum at approximately 30 d of treatment and displaced mainly arachidonic acid. Flaxseed oil supplementation yielded a small increase in atrial EPA but not DHA, whereas olive oil did not significantly change atrial n-3 fatty acids. CONCLUSION: The results of the present study show that dietary n-3 fatty acids are rapidly incorporated into human myocardial phospholipids at the expense of arachidonic acid during high-dose fish-oil supplementation.