Editorial—Special issue of the 7th European workshop on lipid mediators

The Seventh European Workshop on Lipid Mediators (7EWLM) was held at Université catholique de Louvain in Brussels, Belgium September 12-14, 2018. The aim of the workshop was to bring together those researchers and students interested in the field of bioactive lipid mediators. The seventh edition of this biennial workshop was organized by Giulio Muccioli, Mireille Alhouayek, Gerard Bannenberg, Joan Clària, Per-Johan Jakobsson, Xavier Norel, Nils Helge Schebb and Chengcan Yao. The three-day event provided a good opportunity for participants to present their work, and enjoy a variety of presentations by experts, a session for young scientists, an educational session on analytical chemistry of lipid mediators, and poster sessions (see full program and download the abstract book athttps://workshop-lipid.eu//7EWLM/index.php?cat=Program) [...

Stem cells from human apical papilla decrease neuro-inflammation and stimulate oligodendrocyte progenitor differentiation via activin-A secretion

Secondary damage following spinal cord injury leads to non-reversible lesions and hampering of the reparative process. The local production of pro-inflammatory cytokines such as TNF-α can exacerbate these events. Oligodendrocyte death also occurs, followed by progressive demyelination leading to significant tissue degeneration. Dental stem cells from human apical papilla (SCAP) can be easily obtained at the removal of an adult immature tooth. This offers a minimally invasive approach to re-use this tissue as a source of stem cells, as compared to biopsying neural tissue from a patient with a spinal cord injury. We assessed the potential of SCAP to exert neuroprotective effects by investigating two possible modes of action: modulation of neuro-inflammation and oligodendrocyte progenitor cell (OPC) differentiation. SCAP were co-cultured with LPS-activated microglia, LPS-activated rat spinal cord organotypic sections (SCOS), and LPS-activated co-cultures of SCOS and spinal cord adult OPC. We showed for the first time that SCAP can induce a reduction of TNF-α expression and secretion in inflamed spinal cord tissues and can stimulate OPC differentiation via activin-A secretion. This work underlines the potential therapeutic benefits of SCAP for spinal cord injury repair

Altered mRNA Expression of Genes Involved in Endocannabinoid Signalling in Squamous Cell Carcinoma of the Oral Tongue

Little is known about the endocannabinoid (eCB) system in squamous cell carcinoma of the oral tongue (SCCOT). Here we have investigated, at the mRNA level, expression of genes coding for the components of the eCB system in tumour and non-malignant samples from SCCOT patients. Expression of NAPEPLD and PLA2G4E, coding for eCB anabolic enzymes, was higher in the tumour tissue than in non-malignant tissue. Among genes coding for eCB catabolic enzymes, expression of MGLL was lower in tumour tissue while PTGS2 was increased. It is concluded that the eCB system may be dysfunctional in SCCOT

Effects of tumour necrosis factor alpha upon the metabolism of the endocannabinoid anandamide in prostate cancer cells

Tumour necrosis factor a (TNF alpha) is involved in the pathogenesis of prostate cancer, a disease where disturbances in the endocannabinoid system are seen. In the present study we have investigated whether treatment of DU145 human prostate cancer cells affects anandamide (AEA) catabolic pathways. Additionally, we have investigated whether cyclooxygenase- 2 (COX-2) can regulate the uptake of AEA into cells. Levels of AEA synthetic and catabolic enzymes were determined by qPCR. AEA uptake and hydrolysis in DU145 and RAW264.7 macrophage cells were assayed using AEA labeled in the arachidonic and ethanolamine portions of the molecule, respectively. Levels of AEA, related N-acylethanolamines (NAEs), prostaglandins (PG) and PG-ethanolamines (PG-EA) in DU145 cells and medium were quantitated by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. TNF alpha treatment of DU145 cells increased mRNA levels of PTSG2 (gene of COX-2) and decreased the mRNA of the AEA synthetic enzyme N-acylphosphatidylethanolamine selective phospholipase D. mRNA levels of the AEA hydrolytic enzymes fatty acid amide hydrolase (FAAH) and N-acylethanolamine-hydrolyzing acid amidase were not changed. AEA uptake in both DU145 and RAW264.7 cells was inhibited by FAAH inhibition, but not by COX-2 inhibition, even in RAW264.7 cells where the expression of this enzyme had greatly been induced by lipopolysaccharide + interferon. treatment. AEA and related NAEs were detected in DU145 cells, but PGs and PGE(2)-EA were only detected when the cells had been preincubated with 100 nM AEA. The data demonstrate that in DU145 cells, TNFa treatment changes the relative expression of the enzymes involved in the hydrolytic and oxygenation catabolic pathways for AEA. In RAW264.7 cells, COX-2, in contrast to FAAH, does not regulate the cellular accumulation of AEA. Further studies are necessary to determine the extent to which inflammatory mediators are involved in the abnormal endocannabinoid signalling system in prostate cancer

Role of pannexin-1 in the cellular uptake, release and hydrolysis of anandamide by T84 colon cancer cells

The large pore ion channel pannexin-1 (Panx1) has been reported to play a role in the cellular uptake and release of anandamide (AEA) in the hippocampus. It is not known whether this is a general mechanism or limited to the hippocampus. We have investigated this pharmacologically using T84 colon cancer cells. The cells expressed Panx1 at the mRNA level, and released ATP in a manner that could be reduced by treatment with the Panx1 inhibitors carbenoxolone and mefloquine and the Panxl substrate SR101. However, no significant effects of these compounds upon the uptake or hydrolysis of exogenously applied AEA was seen. Uptake by T84 cells of the other main endocannabinoid 2-arachidonoylglycerol and the AEA homologue palmitoylethanolamide was similarly not affected by carbenoxolone or mefloquine. Total release of tritium from [H-3]AEA-prelabelled T84 cells over 10 min was increased, rather than inhibited by carbenoxolone and mefloquine. Finally, AEA uptake by PC3 prostate cancer and SH-SY5Y neuroblastoma cells, which express functional Panx1 channels, was not inhibited by carbenoxolone. Thus, in contrast to the hippocampus, Panx1 does not appear to play a role in AEA uptake and release from the cells studied under the conditions used

Effects of orthotopic implantation of rat prostate tumour cells upon components of the N-acylethanolamine and monoacylglycerol signalling systems : an mRNA study

There is good evidence that the N-acylethanolamine (NAE)/monoacylglycerol (MAG) signalling systems are involved in the pathogenesis of cancer. However, it is not known how prostate tumours affect these systems in the surrounding non-malignant tissue and vice versa. In the present study we have investigated at the mRNA level 11 components of these systems (three coding for anabolic enzymes, two for NAE/MAG targets and six coding for catabolic enzymes) in rat prostate tissue following orthotopic injection of low metastatic AT1 cells and high metastatic MLL cells. The MLL tumours expressed higher levels of Napepld, coding for a key enzyme in NAE synthesis, and lower levels of Naaa, coding for the NAE hydrolytic enzyme N-acylethanolamine acid amide hydrolase than the AT1 tumours. mRNA levels of the components of the NAE/MAG signalling systems studied in the tissue surrounding the tumours were not overtly affected by the tumours. AT1 cells in culture expressed Faah, coding for the NAE hydrolytic enzyme fatty acid amide hydrolase, at much lower levels than Naaa. However, the ability of the intact cells to hydrolyse the NAE arachidonoylethanolamide (anandamide) was inhibited by an inhibitor of FAAH, but not of NAAA. Treatment of the AT1 cells with interleukin-6, a cytokine known to be involved in the pathogenesis of prostate cancer, did not affect the expression of the components of the NAE/MAG system studied. It is thus concluded that in the model system studied, the tumours show different expressions of mRNA coding for key the components of the NAE/MAG system compared to the host tissue, but that these changes are not accompanied by alterations in the non-malignant tissue

The anti-inflammatory compound palmitoylethanolamide inhibits prostaglandin and hydroxyeicosatetraenoic acid production by a macrophage cell line

The anti-inflammatory agent palmitoylethanolamide (PEA) reduces cyclooxygenase (COX) activity in vivo in a model of inflammatory pain. It is not known whether the compound reduces prostaglandin production in RAW264.7 cells, whether such an action is affected by compounds preventing the breakdown of endogenous PEA, whether other oxylipins are affected, or whether PEA produces direct effects upon the COX-2 enzyme. RAW264.7 cells were treated with lipopolysaccharide and interferon-c to induce COX-2. At the level of mRNA, COX-2 was induced > 1000-fold following 24 h of the treatment. Coincubation with PEA (10 mu mol/L) did not affect the levels of COX-2, but reduced the levels of prostaglandins D-2 and E-2 as well as 11- and 15-hydroxyeicosatetraenoic acid, which can also be synthesised by a COX-2 pathway in macrophages. These effects were retained when hydrolysis of PEA to palmitic acid was blocked. Linoleic acidderived oxylipin levels were not affected by PEA. No direct effects of PEA upon the oxygenation of either arachidonic acid or 2-arachidonoylglycerol by COX-2 were found. It is concluded that in lipopolysaccharide and interferon-c-stimulated RAW264.7 cells, PEA reduces the production of COX-2-derived oxylipins in a manner that is retained when its metabolism to palmitic acid is inhibited

Metabolism of 100 nM AEA by DU145 cells.

<p>Panels A show the time courses for the hydrolysis of 100 nM [Et-³H]AEA. Note that the values are per well, and not normalised to the protein content (shown in Panel B). In Panel C, rates of hydrolysis were determined for each experiment from the individual slopes (going through the origin) of the first two time points divided by the protein content. Data are means and 95% confidence intervals, N = 9. For the vehicle and flurbiprofen treated cells, the bootstrapped linear main effects model gave P values of TNFα, 0.19; flurbiprofen, 0.62. The interaction model gave a P value for TNFα x flurbiprofen of 0.80. However, a small effect of flurbiprofen can be masked by the large inter-experimental variation. Expressing the effect of flurbiprofen as % of the corresponding control value gave values of: untreated cells, 90 (81–99.5); TNFα- treated cells 87 (77–96) (means and 95% confidence limits, N = 9). Panels D-E: TLC separation of [Ara-³H]AEA, [³H]arachidonic acid (AA), [³H]PGF_2α and [³H]bimtoprost (Bimat) using ethyl acetate: methanol (90:10 v/v) as solvent system. Panel D shows the complete sampling from a single experiment, and Panel E shows the total recovery for three separate experiments over the R_f range shown. In Panel F, cells were incubated with 100 nM [³H]AEA, labelled in the arachidonoyl part of the molecule for 30 min prior to workup and separation by TLC. Shown are means of individual experiments conducted in triplicate for vehicle (V) and TNFα (T)-treated DU145 cells, and for vehicle and LPS + IFNγ-treated (L/I) RAW264.7 cells.</p