Docosahexaenoic acid inhibits each NLRP3 inflammasome meeting and JNK-mediated mature IL-1β secretion in 5-fluorouracil-treated MDSC: implication in most cancers therapy


DHA (C22:6 n-Three), eicosapentaenoic acid (EPA, C20:5 n-Three), oleic acid (OA, C18:1 n-9), linoleic acid (LA, C18:2 n-6), SP600125 (JNK inhibitor), N-acetyl-l-Cysteine (NAC), chloroquine (CQ) had been bought from Sigma-Aldrich. TEMPOL was obtained from Abcam (France), Bafilomycine A1 from Enzo (Enzo Life Sciences, France) and 5-FU from ACCORD.


Between October 2016 and July 2018, we collected complete blood from metastatic CRC sufferers (n = 46) on the Georges François Leclerc Most cancers Heart (Dijon, France). mCRC sufferers had been recognized in our Most cancers Heart and obtained 5-FU-based chemotherapy (5-FU bolus at a dose of 400 mg/m2 adopted by 5-FU steady infusion at 2400 mg/m2 over 46 h). The 5-FU-based chemotherapy was largely a mixture of 5-FU plus irinotecan or 5-FU plus oxaliplatin. All sufferers gave an knowledgeable consent permitted by the native Ethics Committee. The gathering of blood samples is carried out 24 h after chemotherapy and is permitted by the French authorization (nr. AC2014-2460). No further blood samples past these required for routine testing had been taken. Complete blood of mCRC sufferers was sampled for evaluation earlier than (D0) and 24 h after one cycle of 5-FU chemotherapy on heparinized tubes (BD Biosciences).

FA evaluation by gaz chromatography-negative chemical ionization mass spectrometry

Blood samples had been collected in sufferers earlier than and after 5-FU chemotherapy and processed as beforehand described20. Twenty-five microliters of plasma had been spiked with 25 µl of SI-Combine resolution containing 1300 ng of myristic acid-d3, 5640 ng of palmitic acid-d3, 4200 ng of stearic acid-d3, 3252 ng of LA-d4, 5.2 ng of arachidic acid-d3, 2160 ng of arachidonic acid-d8, 54 ng of behenic acid-d3, 540 ng of DHA-d5, 26 ng of Lignoceric-d4, and 20 ng of cerotic acid-d4 in ethanol. One milliliter of ethanol/butylated hydroxytoluene (50 mg/ml) and 60 µl of potassium hydroxide (10 mol/L) was added to samples earlier than incubation at 56 °C for 45 min underneath argon ambiance. Then, aqueous section extraction was carried out with 2 ml of hexane, after addition of hydrochloric acid (1 ml). The higher natural section was collected after a 10 min centrifugation at 2000g and evaporated to dryness underneath vacuum. In a chemical hood, we disbursed sequentially 5 μl of pentafluorobenzyl bromide (PFB), 90 μl of acetonitrile, and 5 μl of diisopropylbenzylamine earlier than incubation at 37 °C for 30 min and extraction of the ensuing PFB-FAs with 1 ml of water and a couple of ml of hexane. We evaporated to dryness underneath vacuum and solubilized PFB-FAs with 100 μl of hexane. We injected 1 μl of PFB-FAs in pulsed cut up mode on the 7890A gasoline chromatograph utilizing the HP-5MS fused silica capillary column. Gaz chromatography-mass spectrometry situations had been service gasoline, helium at a flow-rate of 1.1 ml/min; injector temperature arrange at 250 °C, pulsed cut up 10; oven temperature arrange at 140 °C, elevated of 5 °C/min to 300 °C, and held for 10 min. The mass spectrometer operates underneath damaging chemical ionization mode with methane as reactant gaz. Ion supply and quadrupole temperatures had been arrange at 150 °C. FAs had been quantified by calculating their relative response ratios to their closest inside normal. We used an Agilent 7890A gasoline chromatograph geared up with a 7683 injector and a 5975C Mass Selective Detector (Agilent Applied sciences) and a GC column HP-5MS fused silica capillary column (30 m × zero.25 mm internal diameter, zero.25 μm movie thickness, Agilent Applied sciences).

Tumor development, eating regimen, and 5-FU therapy

All research with mice had been carried out in accordance with the native tips for animal experimentation. Protocol no. 8821 was permitted by the institutional animal care and use committee of Université de Bourgogne-Franche-Comté. To induce tumor formation, 106 EL4 cells had been subcutaneously injected into feminine C57BL/6J mice (7–9 weeks) from Charles River Laboratories (France). As soon as tumors had been measurable, EL4 tumor-bearing mice had been randomly assigned to both a gaggle of mice day by day fed an isocaloric management eating regimen with sunflower oil or to a Three% DHA-enriched eating regimen (Omegavie DHA90 TG, Polaris Dietary Lipids, France). After 1 week of experimental eating regimen, mice obtained a single intraperitoneal injection of 5-FU at 50 mg per kg physique weight (tumor measurement ~100 mm2). The mice had been fed experimental diets till the tip of the experiment. Tumor development was monitored over the time and tumor floor was calculated in keeping with the formulation: size × width.

Cell tradition and coverings

MSC-2 cell line is CD11b+/Gr-1+ immortalized MDSC obtained from CT-26 tumor-bearing BALB/c mice21.

EL4 thymoma cells and MSC-2 cells had been cultured at 37 °C underneath 5% CO2 in RPMI 1640 with 10% (v/v) warmth inactivated fetal bovine serum penicillin, streptomycin, amphotericin B antibiotic cocktail, all from Dutscher (Dutscher, Brumath, France). Cell strains had been authenticated by examination of morphology and development traits and confirmed to be mycoplasma free. MSC-2 cells had been handled with FAs (20–60 µM) certain to FA free-bovine serum albumin (ratio four:1) (BSA, Sigma-Aldrich) Three h previous to 5-FU therapy at 1 µM or lipopolysaccharide (LPS) (O55:B5, Sigma-Aldrich) at 100 ng/ml.

Era of steady MSC-2 cell line overexpression of V5-tagged mature IL-1β

The coding sequence of mature murine IL-1β with a C-terminal V5 tag was cloned in retroviral assemble pMSCV22. The E-Platinum retroviral packaging cell line was transfected by Lipofectamine 2000 (Invitrogen) with pMSCV plasmid encoding V5-tagged mature IL-1β for retrovirus manufacturing. MSC-2 cells had been transduced with cell-free retrovirus resolution within the presence of eight µg/mL of hexadimethrine bromide (Sigma-Aldrich) for two days. Stably overexpressing V5-tagged mature IL-1β MSC-2 cells had been chosen with 7.5 µg/mL of blasticidin (Invivogen).

Knockdown of ARRB2 expression in MSC-2 cell line

ARRB2 (MISSION shRNA, Sigma-Aldrich) or management shRNA lentivirus vector had been co-transfected with the VSV-G envelope and PAX2 packaging plasmids (Addgene) into HEK293T with lipofectamine 2000 (Invitrogen, Fisher scientific). Lentivirus-containing supernatants had been collected after 48 h of transfection and filtered. MSC-2 cell strains had been transduced by lentiviral particles within the presence of eight µg/mL of hexadimethrine bromide (Sigma-Aldrich) for 48 h. Number of steady shRNA ctrl and ARRB2 cell strains was carried out with 10 µg/mL of puromycin (ACROS Organics, Fisher scientific).

Enzyme-linked immunosorbent assay

IL-1β focus was measured utilizing Mouse IL-1beta/IL-1F2 DuoSet ELISA Equipment (R&D Techniques, France) in keeping with producer’s directions. MSC-2 tradition media was collected 24 h after therapy and plasma was sampled 48 h after 5-FU injection in tumor-bearing mice.

Reverse transcription and quantitative PCR

Whole RNA from MSC-2 was extracted with Trizol (Life Applied sciences) and reverse transcribed with M-MLV reverse transcriptase equipment from Utilized Biosystem (Life applied sciences). Actual-time quantitative polymerase chain response (PCR) was carried out with SYBR™ Inexperienced PCR Grasp Combine from Utilized Biosystem (Life applied sciences) utilizing a StepOnePlus™ Actual-Time PCR System (Utilized Biosystems). The sequence of primers had been: β-actin F: 5′-ATGGAGGGGAATACAGCCC-Three′, R: 5′-TTCTTTGCAGCTCCTTCGTT-Three′, 18S F: 5′-GTAACCCGTTGAACCCCATT-Three′, R: 5′-CCATCCAATCGGTAGTAGCG-Three′, IL-1β F: 5′-GGTCAAAGGTTTGGAAGCAG-Three′, R: 5′-TGTGAAATGCCACCTTTTGA-Three′. Expression was normalized to β-actin and 18 S. Relative expression of RNA targets was decided utilizing the comparative ΔΔCt technique.

Western-blotting evaluation

For whole-protein lysates, MSC-2 had been washed with ice-cold PBS and lysed with ice-cold RIPA buffer containing phosphatase and protease inhibitor cocktail (P2850 and P8340, Sigma-Aldrich). We cleared protein lysate at 13,000g for 15 min at four °C. Whole protein lysates (60 µg) had been resolved by sodium dodecyl sulphate polyacrylamide gel elactrophoresis (SDS-PAGE) and transferred onto a nitrocellulose membrane.

For supernatant precipitation, MSC-2 cells had been handled in Opti-MEM I Lowered Serum Medium (ThermoFisher Scientific) for 24 h. Protein precipitation was carried out utilizing cell tradition supernatant, methanol, and chloroform (ratio 1:1:zero.25, respectively). Thus, one quantity of supernatant (500 µl) was combined with one quantity of methanol (500 µl) and one-fourth quantity of chloroform (125 µl). The combination was vortexed and centrifuged at 16,000g for 10 min. The aqueous methanol layer was faraway from the highest of the samples. Proteins remained on the section boundary between the aqueous methanol layer and the chloroform layer. Two volumes of methanol had been added and the combination was vortexed and centrifuged at 16,000g for 10 min. Supernatant was eliminated with out disturbing the pellet, and the pellet was dried underneath nitrogen gasoline. To complete, pellet was dissolved in 2× loading buffer, incubated 5 min at room temperature after which 5 min at 100 °C. Whole proteins had been resolved by SDS-PAGE and transferred onto a nitrocellulose membrane.

After saturation for one hour with 5% BSA in tris-buffered saline (TBS)—zero.1% Tween-20, membranes had been incubated in a single day at four °C with the first antibody diluted in saturation resolution (1/1000), washed, incubated with the secondary antibody (1/5000) for 1 h at room temperature and washed once more earlier than publicity to ECL (Biorad, France). Photos acquisition was carried out with ImageChemiDocTM XRS (Biorad, France) and densitometry evaluation with Picture LabTM software program 5.1.2 (Biorad, France). The antibodies used are anti-IL-1β (R&D techniques, AF-401), anti-NLRP3 (Adipogen Cryo-2), anti-ASC (Cell Signaling Know-how, B2W8U), anti-cathepsin B (Santa-Cruz S-12), anti-Caspase-1 (Adipogen, Casper-1), anti-p-JNK (Cell Signaling Know-how, 98F2), anti-JNK (Cell Signaling Know-how, 56G8), anti-β-actin (Sigma-Aldrich, A1978), anti-V5 tag (Invitrogen), Horseradish peroxidase-conjugated anti-mouse, anti-goat, and anti-rabbit (Cell Signaling Know-how).

Caspase-1 exercise

To evaluate caspase-1 exercise in MSC-2, the FAM-YVAD-FMK fluorescent probe from Immunochemistry Applied sciences (Bio-Rad, Marnes-la-coquette, France) was used in keeping with the producer’s directions and as beforehand described7.

To evaluate caspase-1 exercise in CD11b+ Gr-1+ MDSC, spleens had been collected from handled tumor-bearing mice 48 h after injection of 5-FU or automobile. Then, they had been manually dissociated and handed via a 70-μm mobile sieve. Purple blood cells had been lysed (NH4Cl zero.83%, KHCO3 zero.1%, EDTA zero.1 mM) and cells had been saturated by utilizing mouse FcR blocking reagent (Miltenyi Biotec, Paris, France). Gr-1+ cells had been first purified by utilizing phycoerythrin-Cyanine 7-conjugated anti-Gr-1 (RB6-8C5, Ozyme, France) and anti-Cyanine seven microbeads (Miltenyi Biotec). Then, purified cells had been incubated with the FAM-YVAD-FMK fluorescent probe in keeping with the producer’s directions and MDSC had been discriminated by utilizing allophycocyanine (APC)-conjugated anti-CD11b (REA592) from Miltenyi Biotec for 20 min at four °C, lifeless cells had been exclude utilizing 7-AAD staining.

To evaluate caspase-1 exercise in MDSC from 5-FU-treated colorectal most cancers (CRC) sufferers, 100 µL of heparinized complete blood obtained earlier than and 24 h after 5-FU therapy had been incubated with the FAM-YVAD-FMK fluorescent probe in keeping with the producer’s directions. Then, cells had been stained for 20 min at room temperature with lineage cocktail PE-Vio770-conjugated anti-CD3 (BW264/56), anti-56 (REA196), anti-19 (REA675), and anti-20 (REA780), PE-conjugated anti-CD33 (REA775), Viogreen-conjugated anti-CD15 (VIMC6), APC-Vio770-conjugated anti-CD14 (TÜK4), and APC-conjugated anti-HLA-DR (AC122) antibodies and viobilityTM 405/452 fixable dye (Miltenyi Biotec) to exclude lifeless cells. After floor staining, 2 mL of purple blood cells lysis/fixation resolution (BD) was added for 10 min, cells had been centrifuged (450 g for 10 min) after which resuspended in movement cytometry staining buffer (eBioscience, Fisher scientific, France).

All occasions had been acquired by a BD LSR-II movement cytometer with BD FACSDiva software program (BD) and knowledge had been analyzed utilizing FlowJo software program (Tree Star).

JNK phosphorylation staining

MDSC (CD11b+ Gr-1+) from tumor-bearing mice had been purified and floor labeled as described above. Cells (MSC-2 and CD11b+ Gr-1+) had been mounted and permeabilized utilizing BD Cytofix/Cytoperm buffer (BD), washed with BD Perm/Wash buffer in accordance producer’s suggestions and saturated with Perm/Wash resolution containing 5% BSA. Main antibody in opposition to p-JNK (G-9, Ozyme, France) was incubated 1 h at four °C, washed and incubated 45 min at four °C with Alexa488-conjugated anti-mouse antibody (A-11001, Life Applied sciences). MDSC had been washed and resuspended in staining buffer (eBioscience, Fisher scientific, France) for movement cytometry evaluation. JNK phosphorylation in MDSC was decided by Median of Fluorescence Depth utilizing FlowJo software program (Tree Star).

ROS detection by movement cytometry

Cells had been handled for eight h with 5-FU (1 µM) alone or together with DHA (60 µM) or N-acetyl-l-cysteine (NAC, 10 mM). MSC-2 had been washed and incubated for 45 min in phenol red-free RPMI containing 10 µM CM-H2DCFDA (Molecular Probes). The cells had been collected and analyzed by movement cytometry. The information had been acquired with a BD LSR-II movement cytometer utilizing BD FACSDiva software program (BD) and analyzed with FlowJo software program (Tree Star).

Immunofluorescence for ASC speck detection

After remedies, cells had been washed with PBS, mounted with four% paraformaldehyde (PFA) at four °C for 10 min, permeabilized with zero.2% Saponin (Sigma Aldrich) and saturated with Three% BSA in PBS for 20 min at room temperature. Samples had been incubated in a single day at four °C with anti-ASC antibody (Cell signaling applied sciences B2W8U). Cells had been washed thrice in PBS after which incubated with secondary Alexa568-conjugated anti-rabbit (Invitrogen) for 30 min at room temperature. After three washes in PBS, samples had been mounted with a drop of ProlongTM diamond antifade mountant containing DAPI (Molecular Probes). Microscopy pictures had been taken on an Axio Imager 2 (Carl Zeiss Microscopy GmbH, Jena, Germany) geared up with an Apotome.2 module (Carl Zeiss GmbH). Photos had been acquired utilizing an AxioCam MRm monochrome CCD digital camera (Carl Zeiss GmbH) with filter units 43 HE (Rhodamine/Alexa568) and 49 (DAPI).

Proximity ligation assay

Cells had been mounted with four% PFA at four °C for 10 min and incubated in an answer of three% BSA and zero.2% Saponin (Sigma Aldrich) for 20 min. Samples had been incubated in a single day at four °C with major antibodies: anti-NLRP3 (Adipogen Cryo-2 or Abcam Ab4207) and anti-IL-1β (R&D techniques, AF-401), anti-ASC (Cell Signaling Know-how, B2W8U), anti-cathepsin B (Santa-Cruz S-12), anti-Caspase-1 (Adipogen, Casper-1) or anti-β-arrestin-2 (Ozyme, C16D9). Cells had been incubated with the suitable probes (anti-Rabbit PLUS, #DUO92002; anti-Goat MINUS, #DUO92006 or anti-Mouse MINUS, #DUO92004) for one hour at 37 °C. Probes had been then ligated for 30 min at 37 °C, washed twice and amplified utilizing the producer’s polymerase for 100 min at 37 °C at the hours of darkness. Cowl glasses had been mounted with a drop of mounting medium containing DAPI (Invitrogen). Microscopy pictures had been taken on an Axio Imager 2 (Carl Zeiss Microscopy GmbH, Jena, Germany) geared up with an Apotome.2 module (Carl Zeiss GmbH). Photos had been acquired utilizing an AxioCam MRm monochrome CCD digital camera (Carl Zeiss GmbH) with filter units 43 HE (Rhodamine/Alexa568) and 49 (DAPI).

Statistical evaluation

Knowledge are introduced as imply ± SD or SEM. Statistical analyses had been carried out utilizing Prism (GraphPad). Knowledge regular distribution was decided utilizing the d’Agostino Pearson take a look at and statistical significance was outlined by Kruskal–Wallis with Dunn’s submit hoc take a look at or one-way ANOVA with Tukey’s submit hoc take a look at. Spearman correlation was calculated between two teams. A worth of p < zero.05 was thought-about statistically important. *p < zero.05; **p < zero.01; ***p < zero.zero01; ****p < zero.0001; ns nonsignificant.

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