POS0346 THE THERAPEUTIC EFFECTS OF OMEGA-6 PUFA (PINOLENIC ACID) ON THE TRANSCRIPTOMIC PROFILE OF ACTIVATED PERIPHERAL BLOOD MONONUCLEAR CELLS ISOLATED FROM HEALTHY CONTROLS AND RHEUMATOID ARTHRITIS PATIENTS

Background:

Globally, Rheumatoid arthritis (RA) is the most common chronic inflammatory arthritis. EULAR recommends patient education and disease modifying anti-rheumatic drugs including advanced targeted therapies for management1 2. Many patients seek advice on a dietary intervention that may improve symptoms. Foods high in omega-3 polyunsaturated fatty acids (PUFAs) is one of the most common recommended based on their anti-inflammatory properties3 4. Previously we showed pinolenic acid (PNLA), an omega-6 (PUFAs) found in pine nuts, reduced lipid uptake, endocytosis and migration of monocyte in vitro. PNLA also reduced IL-6, TNF-α, IL-1β and PGE2 produced by lipopolysaccharide (LPS) activated PBMCs from patients with RA and healthy controls (HCs).

Objectives:

We hypothesis that PNLA inhibits key inflammatory processes in synovities as in diagram.1. We investigated the transcriptomic profile of PNLA treatment on LPS activated PBMCs isolated from HCs and RA patients.

Methods:

Adult RA patients (n=6) were recruited from the Rheumatology Department of University Hospital of Wales together with 6 HCs. Blood was collected after taking signed informed consent. PBMCs were isolated by Ficoll gradient centrifugation and pre-treated with 25 μM PNLA or vehicle and then activated with 100 ng/ml LPS. RNA was extracted followed by library construction and sequencing for whole genomic transcriptome. DEGs were analysed using DESeq2 and pathway analysis was performed using Ingenuity pathway analysis. The study was approved by the Research Ethics Committee for Wales (reference no. 12/WA/0045).

Results:

DEGs were selected with at least differential genes using at least 1.2* fold changes and adjusted p-value of <0.05. PNLA significantly upregulates the expression of PDK4, PAI-1 (SERPINE1), FBP1, and NDRG2. These genes have important roles in metabolic pathways. Pathway analysis predicted upstream activation of nuclear receptors peroxisome proliferator-activated receptor (PPARs) involved in the anti-inflammatory process, and inhibition of NF-κB and STAT1, the major transcription factors of the pro-inflammatory cytokines TNF-α, IL-1, IL-6 and IFN-γ.

Conclusion:

PNLA has significant effects on the regulation of metabolic and inflammatory pathways in PBMCs from RA patients and HCs. Based on these results we demonstrate that PNLA may have beneficial anti-inflammatory effects in patients with RA

References:

[1]Agca R, Heslinga SC, Rollefstad S, Heslinga M, McInnes. IB, Peters MJL, Kvien, TK., Dougados, M, Radner, H, Atzeni, F. and Primdahl, J. 2017. EULAR recommendations for cardiovascular disease risk management in patients with rheumatoid arthritis and other forms of inflammatory joint disorders: 2015/2016 update. Annals of the rheumatic diseases, 76(1), pp.17-28.

[2]Smolen JS, Landewé RBM, Bijlsma JWJ, et al. 2019. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: updateAnnals of the Rheumatic Diseases 2020; 79:685-699.

[3]Chehade L, Jaafar ZA, El Masri D, Zmerly H, Kreidieh D, Tannir H, Itani L, and El Ghoch, M. 2019. Lifestyle Modification in Rheumatoid Arthritis: Dietary and Physical Activity Recommendations Based on Evidence. Current rheumatology reviews, 15(3), pp.209-214.

[4]Marchand NE, Chiu Y-H, Yoshida K, Malspeis S, Sparks JA, Costenbader K, et al. Threshold Level for Long-term Healthy Diet Adherence to Reduce the Risk of Rheumatoid Arthritis Among Women in a Prospective Cohort Using a Marginal Structural Model Approach.:25.

Diagram 1.

Disclosure of Interests:

None declared

Involvement of the 5-lipoxygenase/leukotriene A4 hydrolase pathway in 7,12-dimethylbenz[a]anthracene (DMBA)-induced oral carcinogenesis in hamster cheek pouch, and inhibition of carcinogenesis by its inhibitors

Previous studies have shown that aberrant arachidonic acid (AA) metabolism, especially cyclooxygenase-2 (Cox-2) and 5-lipoxygenase (5-Lox) pathways, are activated during oral carcinogenesis, and can be targeted for cancer prevention. This study was designed to investigate the importance of 5-Lox/leukotriene A4 hydrolase (LTA4H) pathway of AA metabolism in 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster cheek pouch carcinogenesis. In a short-term study, topical application of DMBA for 3 weeks induced severe inflammation and aberrant AA metabolism. Subsequent topical treatment with zileuton, celecoxib, or their combination for 1 week significantly suppressed aberrant AA metabolism and cell proliferation in the oral epithelium. Interestingly, zileuton was effective in inhibiting biosynthesis of multiple AA metabolites, including leukotriene B4 (LTB4), 5-, 12-, 15-hydroxyeicosatetraenoic acid and prostaglandin E2 (PGE2), while celecoxib only suppressed PGE2 biosynthesis significantly at a high dose. In a long-term carcinogenesis study topical application of LTB4 or PGE2 enhanced oral carcinogenesis by increasing the incidence and volume of visible tumors, and the incidence of squamous cell carcinoma (SCC). To further examine the role of LTB4 in oral carcinogenesis, two LTA4H inhibitors, bestatin and SA6541, were evaluated in a long-term chemoprevention experiment. Both agents significantly inhibited SCC, and such an inhibition correlated with reduced levels of LTB4 in hamster cheek pouch. In summary, our studies have demonstrated that 5-Lox/LTA4H pathway is one of the major AA-metabolizing pathways involved in DMBA-induced oral carcinogenesis in hamsters, and may be targeted for chemoprevention.

Inhibitory effects of black tea theaflavin derivatives on 12-O-tetradecanoylphorbol-13-acetate-induced inflammation and arachidonic acid metabolism in mouse ears

Tea has been shown to possess several health beneficial properties primarily due to its polyphenolic content. The major polyphenolic compounds in black tea leaves are theaflavins (TFs) formed by oxidative coupling of catechins in tea leaves during its processing. In this paper, we report the characterization of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear inflammatory model and the inhibitory effects of major black tea TFs derivatives on this inflammation. In addition, the effect on inflammatory biomarkers, such as proinflammatory cytokines and arachidonic acid metabolites, are reported as well. A single topical application of TPA to ears of CD-1 mice induced a time- and dose-dependent increase in edema as well as formation of proinflammatory cytokine proteins interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in mouse ears. A single topical application of equimolar of black tea constituents (TF, theaflavin-3-gallate, theaflavin-3'-gallate, and theaflavin-3,3'-digallate) strongly inhibited TPA-induced edema of mouse ears. Application of TFs mixture to mouse ears 20 min prior to each TPA application once a day for 4 days inhibited TPA-induced persistent inflammation, as well as TPA-induced increase in IL-1beta and IL-6 protein levels. TFs also inhibited arachidonic acid (AA) metabolism via both cyclooxygenase (COX) and lipoxygenase pathways. This observation was substantiated by decreased amounts of AA metabolites prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) levels. Combined application of TF and sulindac, a nonsteroidal anti-inflammatory drug resulted a significant synergetic anti-inflammatory effect. Oral administration of TFs or the hot water extract of black tea leaves also significantly inhibited TPA-induced edema in mouse ears. In conclusion, proinflammatory cytokines, IL-1beta and IL-6, as well as the intermediated metabolites of AA, PGE2, and LTB4 are good biomarkers for inflammation. Black tea constituents, TF and its derivatives, had strongly anti-inflammatory activity in vivo which may be due to their ability to inhibit AA metabolism via lipoxygenase and COX pathways.