Antitumor effects of ajulemic acid (CT3), a synthetic non-psychoactive cannabinoid.

One of the endogenous transformation products of tetrahydrocannabinol (THC) is THC-11-oic acid, and ajulemic acid (AJA; dimethylheptyl-THC-11-oic acid) is a side-chain synthetic analog of THC-11-oic acid. In preclinical studies, AJA has been found to be a potent anti-inflammatory agent without psychoactive properties. Based on recent reports suggesting antitumor effects of cannabinoids (CBs), we assessed the potential of AJA as an antitumor agent. AJA proved to be approximately one-half as potent as THC in inhibiting tumor growth in vitro against a variety of neoplastic cell lines. However, its in vitro effects lasted longer. The antitumor effect was stereospecific, suggesting receptor mediation. Unlike THC, however, whose effect was blocked by both CB(1) and CB(2) receptor antagonists, the effect of AJA was inhibited by only the CB(2) antagonist. Additionally, incubation of C6 glioma cells with AJA resulted in the formation of lipid droplets, the number of which increased over time; this effect was noted to a much greater extent after AJA than after THC and was not seen in WI-38 cells, a human normal fibroblast cell line. Analysis of incorporation of radiolabeled fatty acids revealed a marked accumulation of triglycerides in AJA-treated cells at concentrations that produced tumor growth inhibition. Finally, AJA, administered p.o. to nude mice at a dosage several orders of magnitude below that which produces toxicity, inhibited the growth of subcutaneously implanted U87 human glioma cells modestly but significantly. We conclude that AJA acts to produce significant antitumor activity and effects its actions primarily via CB(2) receptors. Its very favorable toxicity profile, including lack of psychoactivity, makes it suitable for chronic usage. Further studies are warranted to determine its optimal role as an antitumor agent.

Gammalinolenic acid, an unsaturated fatty acid with anti-inflammatory properties, blocks amplification of IL-1 beta production by human monocytes.

Administration of gammalinolenic acid (GLA), an unsaturated fatty acid, reduces joint inflammation in patients with rheumatoid arthritis. Addition of GLA in vitro suppresses release of IL-1beta from human monocytes stimulated with LPS. LPS-induced IL-1beta release is followed by IL-1-induced IL-1beta release, an amplification process termed autoinduction. We show here with peripheral blood monocytes from normal volunteers and from patients with rheumatoid arthritis by using IL-1R antagonist to block autoinduction and IL-1alpha stimulation to simulate autoinduction that approximately 40% of IL-1beta released from LPS-stimulated cells is attributable to autoinduction and that GLA reduces autoinduction of IL-1beta while leaving the initial IL-1beta response to LPS intact. Experiments with cells in which transcription and protein synthesis were blocked suggest that GLA induces a protein that reduces pro-IL-1beta mRNA stability. IL-1beta is important to host defense, but the amplification mechanism may be excessive in genetically predisposed patients. Thus, reduction of IL-1beta autoinduction may be protective in some patients with endotoxic shock and with diseases characterized by chronic inflammation.

Polyunsaturated fatty acids and rheumatoid arthritis.

Rheumatoid arthritis is characterized by infiltration of T lymphocytes, macrophages and plasma cells into the synovium, and the initiation of a chronic inflammatory state that involves overproduction of proinflammatory cytokines and a dysregulated T-helper-1-type response. Eicosanoids synthesized from arachidonic acid and cytokines cause progressive destruction of cartilage and bone. The n-6 polyunsaturated fatty acid gamma-linolenic acid is the precursor of di-homo-gamma-linolenic acid. The latter and the n-3 polyunsaturated fatty acid eicosapentaenoic acid, which is found in fish oil, are able to decrease the production of arachidonic acid-derived eicosanoids and to decrease the production of proinflammatory cytokines and reactive oxygen species, and the reactivity of lymphocytes. A number of double-blind, placebo-controlled trials of gamma-linolenic acid and fish oil in rheumatoid arthritis have shown significant improvements in a variety of clinical outcomes. These fatty acids should be included as part of the normal therapeutic approach to rheumatoid arthritis. However, it is unclear what the optimal dosage of the fatty acids is, or whether there would be extra benefit from using them in combination.

Oxidative metabolism of anandamide.

In addition to the well studied hydrolytic metabolism of anandamide, a number of oxidative processes are also possible. Several routes somewhat analogous to the metabolism of free arachidonic acid have been reported. These involve mediation by various lipoxygenases and COX-2 and lead to ethanolamide analogs of the prostaglandins and HETES. The physiological significance of these products is not well understood at this time. There are also preliminary data suggesting a pathway involving oxidation of the hydroxy group of anandamide to a putative metabolite, N-arachidonyl glycine (AA-gly). This molecule displays activities in experimental models that suggest that it may play a role in some of the activities attributed to its precursor, anandamide.

Human peripheral blood T lymphocyte proliferation after activation of the T cell receptor: effects of unsaturated fatty acids.

Oils enriched in certain polyunsaturated fatty acids suppress joint pain and swelling in rheumatoid arthritis patients with active synovitis. Because T lymphocyte activation is important for propagation of joint tissue injury in patients with rheumatoid arthritis, we examined the effects of fatty acids added in vitro on proliferation of human T lymphocytes stimulated with monoclonal antibodies to CD3 and CD4. Unsaturated fatty acids reduced T cell proliferation in a dose dependent manner (dihomogammalinolenic acid > gammalinolenic acid > eicosapentaenoic acid > arachidonic acid). Removal of fatty acids from cultures before cell stimulation did not change the effects, but addition of fatty acids after cell stimulation failed to reduce T cell responses. The saturated palmitic acid did not influence T cell growth. These studies indicate that small changes in cellular fatty acids can have profound effects on early events in T cell signaling and on T cell function.

Effects of gammalinolenic acid on interleukin-1 beta and tumor necrosis factor-alpha secretion by stimulated human peripheral blood monocytes: studies in vitro and in vivo.

BACKGROUND: Oils enriched in gammalinolenic acid, an unsaturated fatty acid, reduce joint pain and swelling in patients with rheumatoid arthritis. The cytokines interleukin-1 beta and tumor necrosis factor-alpha appear to contribute directly to joint tissue damage in patients with rheumatoid arthritis. Agents designed to interfere with the actions of interleukin-1 beta and tumor necrosis factor-alpha are being used to treat rheumatoid arthritis. METHODS: We examined the influence of gammalinolenic acid added to cells in vitro and administered orally in vivo on interleukin-1 beta and tumor necrosis factor-alpha secretion from activated human peripheral blood monocytes. Secretion of both cytokines was reduced by gammalinolenic acid. Administration of safflower oil as a polyunsaturated fatty acid control devoid of gammalinolenic acid did not change secretion of either cytokine. CONCLUSION: Suppression of IL-beta and TNF-alpha secretion by activated cells may be one mechanism whereby gammalinolenic acid suppresses synovitis in patients with rheumatoid arthritis.

Dimethylheptyl-THC-11 oic acid: a nonpsychoactive antiinflammatory agent with a cannabinoid template structure.

OBJECTIVE: To assess the antiinflammatory activity of dimethylheptyl-THC-11 oic acid (DMH-11C), a nonpsychoactive synthetic derivative of tetrahydrocannabinol. METHODS: Acute inflammation was induced by injection of interleukin-1beta and tumor necrosis factor alpha into subcutaneous air pouches formed on the backs of mice. Inflammation was quantified 6 hours later by pouch fluid leukocyte counts. Adjuvant-induced polyarthritis in rats was used as a model of chronic inflammation and joint tissue injury. Animals were either untreated, treated with safflower oil, or treated with DMH-11C in safflower oil. Arthritis was assessed by clinical observation and by histomorphologic evaluation of tibiotarsal joints. RESULTS: Oral administration of DMH-11C reduced the accumulation of pouch fluid leukocytes and significantly reduced the severity of adjuvant-induced polyarthritis. Histopathologic studies of tibiotarsal joints showed that DMH-11C treatment attenuated pannus formation and joint tissue injury. CONCLUSION: DMH-11C suppresses acute inflammation in the subcutaneous air pouch in mice and chronic joint inflammation characteristic of adjuvant disease in rats. These results demonstrate the potential use of this nonpsychoactive cannabinoid as an antiinflammatory agent.

Oral administration of unsaturated fatty acids: effects on human peripheral blood T lymphocyte proliferation.

Oils enriched in certain polyunsaturated fatty acids suppress joint pain and swelling in rheumatoid arthritis (RA) patients. Because T lymphocyte activation is important to propagation of joint tissue injury in patients with RA, we examined the effects of fatty acids administered by mouth in vivo on proliferation of human lymphocytes activated through the T cell receptor complex. T cell proliferation was reduced after oral administration of 2.4 g gammalinolenic acid in capsules of borage seed oil. Oral administration of oils enriched in linoleic acid, the parent n-6 fatty acid, and alpha linolenic acid, the parent n-3 fatty acid, did not influence growth of stimulated cells. Fatty acid analyses indicated that suppression of lymphocyte proliferation after gammalinolenic acid administration was associated with increased plasma and peripheral blood mononuclear cell concentrations of gammalinolenic acid and dihomogammalinolenic acid.

Gammalinolenic acid and dihomogammalinolenic acid suppress the CD3-mediated signal transduction pathway in human T cells.

Gammalinolenic acid (GLA; 18:3n6) and dihomogammalinolenic acid (DGLA; 20:3n6) suppress lymphocyte activation, and GLA administration reduces joint swelling and tenderness in rheumatoid arthritis patients with active synovitis. In an effort to dissect the mechanisms whereby GLA, DGLA, and other fatty acids influence lymphocyte function, we examined their effects on anti-CD3 monoclonal antibody (mAb)-mediated early signaling events in human T cells. Peripheral blood mononuclear cells from healthy individuals were incubated overnight at 37 degrees C with or without 10 microg/ml fatty acid and then loaded with the calcium binding fluorescent dye indo-1. Fatty acids did not affect the efficiency of indo-1 loading, and they did not alter cell surface membrane expression of the CD3 molecule. Anti-CD3 mAb (G19-4)-induced intracellular calcium [(Ca2+)i] changes were monitored by flow cytometry in negatively selected human T cells. The ratio of violet to blue fluorescence, which is proportional to (Ca2+)i, was measured over time. Cells enriched with GLA and DGLA but not cells enriched with eicosapentaenoic acid (20:5n3) displayed a significant reduction in anti-CD3 mAb-induced early and late (Ca2+)i responses. T cells loaded with GLA, DGLA, or medium alone displayed similar increases in (Ca2+)i in response to the endoplasmic reticulum Ca2(+)-ATPase inhibitor thapsigargin. Anti-CD3 mAb-mediated inositol phosphate production was also diminished in GLA- and DGLA-treated cells. These experiments suggest that GLA and DGLA suppress T cell activation by interfering with early events in the signal transduction pathway.

Effects of unsaturated fatty acids on interleukin-1beta production by human monocytes.

Dihomogammalinolenic acid is derived from gammalinolenic acid, administration of which suppresses joint inflammation. It is reported here that interleukin 1beta (IL-1beta) production by human monocytes is enhanced markedly when cells are incubated 18-24 h with the polyunsaturated fatty acids dihomogammalinolenic acid (DGLA) and arachidonic acid (AA), then stimulated with lipopolysaccharide. Effects of eicosapentaenoic acid (EPA) on IL-1beta production are minimal, and palmitic acid (PA) does not influence IL-1beta production.

gamma-Linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial.

OBJECTIVE: To assess the clinical efficacy and adverse effects of gamma-linolenic acid (GLA), a plant seed oil-derived unsaturated fatty acid that suppresses inflammation and joint tissue injury in animal models, in the treatment of active rheumatoid arthritis (RA). METHODS: Fifty-six patients with active RA were randomized to treatment groups in a 6-month, double-blind trial of GLA versus placebo. This was followed by a 6-month, single-blind trial during which all patients received GLA. Patients were treated with 2.8 gm/day of GLA as the free fatty acid or with sunflower seed oil (placebo) administered in identical capsules. RESULTS: Treatment with GLA for 6 months resulted in statistically significant and clinically relevant reductions in the signs and symptoms of disease activity in patients with RA. Overall meaningful responses (at least 25% improvement in 4 measures) were also better in the GLA treatment group (14 of 22 patients versus 4 of 19 in the placebo group; P = 0.015). During the second 6 months, both groups exhibited improvement in disease activity. Thus, patients taking GLA during the entire study showed progressive improvement during the second 6 months. In this group, 16 of 21 patients showed meaningful improvement at 12 months compared with study entry. CONCLUSION: GLA at doses used in this study is a well-tolerated and effective treatment for active RA. GLA is available as a component of several plant seed oils and is usually taken in far lower doses than were used in this trial. It is not approved in the United States for the treatment of any condition, and should not be viewed as therapy for any disease. Further controlled studies of its in RA are warranted.

Effects of unsaturated fatty acids on expression of early response genes in human T lymphocytes.

Administration of gamma-linolenic acid, which is converted rapidly to dihomo-gamma-linolenic acid (DGLA), reduces joint swelling and tenderness in patients with rheumatoid arthritis. Joint tissue inflammation in patients with rheumatoid arthritis is due in part to activation of T lymphocytes. DGLA suppresses T cell activation and production of interleukin-2 (IL-2). The protooncogenes c-myc and c-fos are early response genes which are critical to regulation of T cell proliferation. We therefore examined the effects of gamma-linolenic acid and other unsaturated fatty acids on c-myc and c-fos expression by means of the polymerase chain reaction and Northern blotting. IL-2 production by the human T cell line Jurkat is dependent on a fall in mRNA for c-myc and a rise in mRNA for c-fos. The data presented here indicate that reduction of steady-state levels of mRNA for c-myc and rises in steady-state levels of mRNA for c-fos are both reduced markedly in cells incubated with DGLA. Cells incubated with arachidonic acid, eicosapentaenoic acid or oleic acid exhibit more modest changes in expression of these early response genes.

Botanical lipids: effects on inflammation, immune responses, and rheumatoid arthritis.

OBJECTIVE: This review discusses the rationale and experimental data that led to clinical trials of certain botanical lipids, mainly gammalinolenic acid (GLA), for the treatment of rheumatoid arthritis (RA). DATA SOURCES: Pertinent articles and reviews, and a bibliographic database in English using the following indexing terms: rheumatoid arthritis, fatty acids, gammalinolenic acid, lymphocytes, and monocytes, were used. STUDY SELECTION: All clinical trials in which GLA was used to treat arthritis are included in this review. Data from appropriately peer reviewed in vitro and animal experiments evaluating the effects of botanical lipids as regulators of cell activation and immune responses are also reviewed. DATA SYNTHESIS: GLA treatment is associated with clinical improvement in patients with RA, as evaluated by duration of morning stiffness, joint pain and swelling, and ability to reduce other medications. However, studies vary in terms of duration, GLA dose, whether or not they were placebo controlled, and, if so, what placebo was used, criteria for evaluation, and use of concomitant medication. Studies done in vitro generally indicated that GLA reduces lymphocyte activation and production of mediators of inflammation. CONCLUSIONS: A small number of studies suggest that GLA is effective treatment for RA patients. Further controlled studies of its use in RA seem warranted.

Differential regulation of human T lymphocyte protein kinase C activity by unsaturated fatty acids.

Administration of gamma-linolenic acid suppresses active synovitis in patients with rheumatoid arthritis. We therefore examined the effects of gamma-linolenic acid and its first metabolite, dihomo-gamma-linolenic acid, on protein kinase C, a key element in transduction of signals from cell surface to nucleus. We report here that gamma-linolenic acid and dihomo-gamma-linolenic acid suppress total protein kinase C activity, but facilitate translocation of protein kinase C activity from cytosol to membrane in human peripheral blood T lymphocytes stimulated with phorbol 12-myristate 13-acetate. Arachidonic acid and eicosapentaenoic acid do not influence total protein kinase C activity and have only modest effects on enzyme translocation. These findings in whole cells are in contrast to results of experiments performed with isolated protein kinase C, in which unsaturated fatty acids uniformly enhance protein kinase C activity. The differential effects of unsaturated fatty acids underscore the complexity of protein kinase C regulation and indicate that gamma-linolenic and dihomo-gamma-linolenic acids influence T lymphocyte protein kinase C metabolism in a manner that is unique among unsaturated fatty acid precursors of eicosanoids.

Marine and botanical lipids as immunomodulatory and therapeutic agents in the treatment of rheumatoid arthritis.

Fish and plant seed fatty acids have antiinflammatory and immunomodulating properties that make them of potential use in the treatment of rheumatoid arthritis. A better understanding of their effects on the immune system ultimately may lead to the development of more benign therapy for rheumatoid arthritis patients.

Stimulatory effect of unsaturated fatty acids on the level of plasminogen activator inhibitor-1 mRNA in cultured human endothelial cells.

To determine whether unsaturated fatty acids induce changes in the mRNA level of plasminogen activator inhibitor type-1 (PAI-1), Northern analyses were performed on human umbilical vein endothelial cells (HUVEC) and vascular smooth muscle cells that were treated with two common fatty acids. Supplementation of cultured HUVEC with docosahexanoic acid (DHA) or with dihomogamma linolenic acid (DGLA), resulted in a concentration dependent, specific increase of the PAI-1 transcript levels, which was detectable within 2 h. DHA and DGLA treatment of smooth muscle cells did not result in changes in the PAI-1 mRNA levels. Homology search of the upstream regulatory region of the PAI-1 gene sequences identified a consensus nucleotide sequence for a fatty acid-responsive element. Our results indicate that unsaturated fatty acids selectively increase PAI-1 mRNA levels in endothelial cells, the primary source of circulating PAI-1 in vivo.

Effects of fatty acids on proliferation and activation of human synovial compartment lymphocytes.

The object of this study was to determine the effects of eicosanoid precursor fatty acids on activation and proliferation of T lymphocytes from synovial fluid and synovial tissue of rheumatoid arthritis patients. Proliferation was determined by direct cell counts; phenotypic characterization of surfaces molecules was by cytofluorometric analysis. Dihomogammalinolenic acid, arachidonic acid, and eicosapentaenoic acid suppressed proliferation of interleukin-2-dependent lymphocytes by as much as 80%; cell viability was not altered by fatty acids. Administration of particular fatty acids may prove to be a useful therapeutic intervention in rheumatoid arthritis patients because of their ability to suppress activation and proliferation of synovial compartment T lymphocytes.

Suppression of monosodium urate crystal-induced inflammation by black currant seed oil.

The subcutaneous air pouch formed in Sprague-Dawley rats was used to study the effect of diets enriched in black currant seed oil (BCSO) on acute inflammation induced by monosodium urate crystals. The BCSO enriched diet suppressed significantly both the cellular and fluid phases of inflammation (polymorphonuclear leucocyte and exudate accumulation). In contrast, administration of normal chow or of a diet enriched in safflower oil (polyunsaturated fatty acid control) did not influence monosodium urate crystal-induced inflammation in this model. The findings indicate that a diet which provides both n-6 (gammalinolenic acid) and n-3 (alpha-linolenic acid) fatty acids as substrates alternative to arachidonatic acid for oxidative metabolism, modifies monosodium urate crystal-induced acute inflammation.