Induction of cyclooxygenase-2 expression by allergens in lymphocytes from allergic patients

Abstract

Cyclooxygenase (COX) is a key enzyme in prostaglandin (PG) synthesis. Up-regulation of COX-2 expression is responsible for increased PG release during inflammatory conditions and is thought to be also involved in allergic states. In this study, we demonstrate that in human T, B and natural killer lymphocytes from allergic patients, COX-2 expression became induced upon cell challenge with specific allergens and that this process is presumably IgE dependent and occurs after CD23 receptor ligation. This induction took place at both mRNA and protein levels and was accompanied by PGD 2 release. IgE-dependent lymphocyte treatment elicited, in parallel, an activation of the MAPK p38 and extracellular signal-regulated kinase 1/2, an enhancement of calcineurin (CaN) activity, and an increase of the DNA-binding activity of the nuclear factor of activated T cells and of NF-jB, with a concomitant decrease in the levels of the cytosolic inhibitor of jB, IjB. In addition, specific chemical inhibitors of MAPK, such as PD098059 and SB203580, as well as MG-132, an inhibitor of proteasomal activity, abolished allergen-induced COX-2 up-regulation, suggesting that this process is mediated by MAPK and NF-jB. However, induction of COX-2 expression was not hampered by the CaN inhibitor cyclosporin A. We also examined the effect of a selective COX-2 inhibitor, NS-398, on cytokine production by human lymphocytes. Treatment with NS-398 severely diminished the IgE-dependently induced production of IL-8 and TNF-a. These results underscore the relevant role of lymphocyte COX-2 in allergy and suggest that COX-2 inhibitors may contribute to the improvement of allergic inflammation through the reduction of inflammatory mediator production by human lymphocytes.

Histamine production by human neutrophils

“…Human basophils were purified using the Basophil Isolation Kit II (Miltenyi Biotec S.L., Madrid, Spain) following the manufacturer's instructions. Human lymphocytes were isolated as described previously (19). Highly purified human eosinophils were isolated using the Eosinophil Isolation Kit (Miltenyi Biotec) following the manufacturer's instructions, which is based on a previously described method (20).…”

Oxidative stress, chronic disease, and muscle wasting

“…Finally, phospholipase A 2 (PLA 2 ) is a family of enzymes that deacetylate phospholipids releasing free fatty acids such as arachidonic acid 238. Arachidonic acid is converted to inflammatory leukotrienes and prostaglandins by 5‐lipoxygenase and cyclooxygenase, respectively 39, 272. Two PLA 2 isoforms contribute to skeletal muscle ROS.…”

Comparison of the Immunosuppressive Effects of Dexamethasone, Flunixin Meglumine and Meloxicam on the In Vitro Response of Calf Peripheral Blood Mononuclear Cells

“…For lymphocyte proliferation, PBMCs were seeded in 96-well microplates at a density of 1×10 6 cells/well in a final volume of 200 μl/well of RPMI-1640 medium supplemented with 10% fetal calf serum (FCS). Each sample was cultured with 10 g/ml phytohemagglutinin (PHA; Sigma, St. Louis, MO, U.S.A.) [24] alone, PHA and DEX (Sigma; 10, 15 or 20 μg/ml) [13,20], PHA and FLU (Sigma; 10, 25 or 50 μg/ml) [2,12] or PHA and MEL (Nippon Boehringer Ingelheim Co., Ltd., Tokyo, Japan; 10, 25 or 50 μg/ml) [14].…”

“…These findings are important for assessing the indications and complications of NSAIDs in calves. Recent findings in humans suggest that COX-2-selective NSAIDs act as immunosuppressants and could have applications in anti-inflammatory therapy [6,9]. We believe that it is necessary to reexamine the usage of NSAIDs in the treatment of calves.…”