Earlier studies demonstrated that dietary w-3 polyunsaturated fatty acid (PUFA) supplementation attenuates the chemotactic response of neutrophils and the generation of leukotriene (LT) B4 by neutrophils stimulated with calcium ionophore; however, the mechanisms and relationship ofthese effects were not examined. Neutrophils and monocytes from eight healthy individuals were examined before and after 3 and 10 wk of dietary supplementation with 20 g SuperEPA daily, which provides 9.4 g eicosapentaenoic acid (EPA) and 5 g docosahexaenoic acid.The maximal neutrophil chemotactic response to LTB4, assessed in Boyden microchambers, decreased by 69% after 3 wk and by 93% after 10 wk from prediet values. The formation of 13Hlinositol tris-phosphate (IP3) by I3HIinositol-labeled neutrophils stimulated by LTB4 decreased by 71% after 3 wk (0.033±0.013% [3Hi release, mean±SEM) and by 90% after 10 wk (0.011±0.011%) from prediet values (0.114±0.030%) as quantitated by #-scintillation counting after resolution on HPLC. LTB4-stimulated neutrophil chemotaxis and IP3 formation correlated significantly (P < 0.0001); each response correlated closely and negatively with the EPA content of the neutrophil phosphatidylinositol (PI) pool (P = 0.0003 and P = 0.0005, respectively). Neither the affinities and densities of the high and low affinity LTB4 receptors on neutrophils nor LTB4-mediated diglyceride formation changed appreciably during the study. Similar results were observed in neutrophils activated with platelet-activating factor (PAF). The summed formation of LTB4 plus LTB5 was selectively inhibited in calcium ionophore-stimulated neutrophils and was also inhibited in zymosan-stimulated neutrophils. The inhibition of the summed formation of LTB4 plus LTB5 in calcium ionophorestimulated neutrophils and in zymosan-stimulated neutrophils did not correlate significantly with the EPA content of the PI pool. The data indicate that dietary w-3 PUFA supplementation inhibits the autoamplification of the neutrophil inflammatory response by decreasing LTB4 formation through the inactivation of the LTA epoxide hydrolase and independently by inhibiting LTB4-(and PAF) stimulated chemotaxis by attenuating the formation of IP3 by the PI-selective phospholipase C. This is the initial demonstration that dietary W-3 PUFA Address reprint requests to Richard I. Sperling,
Pilocarpine-induced saliva of the tick, Ixodes dammini, inhibited platelet aggregation triggered by ADP and collagen, as well as platelet-aggregation factor. In addition, we found apyrase activity (which degrades ATP and ADP to AMP and orthophosphate) and an anticoagulant. We showed the presence of prostaglandin E2 (PGE2) by bioassay and radioimmunoassay. This saliva inhibited interleukin 2 production by T cell hybridomas, an activity consistent with that of PGE2. A kininase was demonstrated, and this may counteract the algesia- and edema-promoting properties of PGE2. Together, these salivary components produce antihemostatic, antiinflammatory, and immunosuppressive effects that may facilitate feeding, as well as transmission of tick-borne pathogens.
We have studied cells dispersed with proteolytic enzymes from rheumatoid arthritic synovectomy specimens to determine the cell type(s) responsible for joint destruction these cells suggests that they may be involved in joint destruction in vivo. The precise origin of these synovial cells and the mechanisms responsible for the sustained production of collagenase at a high rate remain unidentified. Rheumatoid arthritis (RA) is frequently accompanied by progressive destruction of joint structures, which is found predominantly in regions adjacent to masses of proliferating cells. Cultures of rheumatoid synovial tissue (containing, for example, proliferating lining cells, including those with macrophage properties, blood vessels, mononuclear cells, and fibroblasts) release collagenases capable of degrading undenatured collagen (1, 2) as well as prostaglandins which can accelerate bone resorption by osteoclasts (3, 4). It has not been determined previously which cells in these organ cultures are responsible for the release of such substances. Fibroblasts can be grown from human synovial explants, but we were previously unable to detect collagenase (EC 3.4.24.3) (2), and found only small amounts of prostaglandins (PGE2) in these culture media (3). This contrasts with rabbit skin and synovial fibroblast cultures, which produce collagenase under some circumstances (5, 6). Recently, cultures of guinea pig macrophages have been shown to produce collagenase after stimulation by endotoxin (7) or by products of lymphocytes treated with phytohemagglutinin or specific antigens (8).We reasoned that the methods of culturing cells from synovial explants favored the growth of cells, usually fibroblasts, that might not be responsible for the destructive effects of proliferating synovium in RA. We therefore examined the heterogeneous population of cells from rheumatoid synovia for the ability to produce collagenase and PGE2, possible functional markers for certain of the potentially destructive cells in RA. Using proteolytic enzymes for dispersion of cells, we found that cells adherent to the surface of the culture vessels produce high quantities of collagenase and PGE2. Culture Methods. Within 2 hr after surgery, the sample was washed three times with Dulbecco's calcium-and magnesium-free phosphate-buffered saline (GIBCO), and pieces of the superficial layer of synovium of about 2 mm3 were cut and placed in Dulbecco's modification of Eagle's medium (GIBCO), supplemented with 100 units of penicillin and 100 isg of streptomycin per ml (GIBCO), and containing 4 mg/ml of Clostridiopeptidase A (Worthington Biochemical CLS, 125-200 units/mg) sterilized through a 0.20 gm filter (Nalge). The tissue fragments (0.5-1.0 g) were further divided with scissors in a 100 mm plastic petri dish (Falcon) and were then incubated for 3 or 4 hr in 20 ml of medium at 370 in a moist atmosphere of 5% carbon dioxide and 95% air.The digest was well mixed many times by aspiration into and expulsion from a pasteur pipette. An equal volume of 0.05% tryps...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.