HSP70 is a adverse regulator of NLRP3 inflammasome activation


LPS (L3024), ATP (A7699) and nigericin (N7143) had been bought from Sigma-Aldrich (St. Louis, MO, USA). MSU (tlr-msu) was bought from Invivogen (San Diego, CA, USA). Alum (77161) was bought from Thermo-Scientific (Thermo Fisher Scientific, MA, USA). M-CSF (216-MC) was bought from R&D Methods (Lille, France). Recombinant HSP70 was kindly supplied by Carmen Garrido’s workforce.

Cell tradition

Human myeloid THP-1 cells had been obtained from the American Sort Tradition Assortment (ATCC—Manassas, VA, USA) and had been grown in RPMI 1640 with ultraglutamine (Lonza, Basel, Switzerland) supplemented with 10% (vol/vol) fetal bovine serum (FBS; Lonza) and with Pen/Strep Amphotericin B (PSA, Lonza) 1%, in an environment of 95% air and 5% CO2 at 37 °C. Previous to the experiments THP-1 cells had been primed with LPS (10 ng/mL, Sigma-Aldrich) for 20 h. In some experiments a warmth shock was carried out by incubating the cells at 42 °C for 1 h. Cells had been then left at 37 °C for two h.


All animals had been bred and maintained in line with each the FELASA and the Animal Experimental Ethics Committee Pointers (College of Burgundy, France). Animals had been used between 6 and 22 weeks of age. Feminine C57BL/6 mice (aged 6–eight weeks) had been obtained from Charles River Laboratories (Saint Germain sur l’Arbresle, France). C57BL/6 HSP70−/− mice had been generated by a 12-kb deletion of each HSP70.1 and HSP70.Three-coding areas18 and had been obtained from the Mutant Mouse Useful resource and Analysis Middle (MMRRC), bred and maintained within the Cryopréservation, Distribution, Typage et Archivage Animal (CDTA-Orléans, France).

In vivo experiments

For the hyperthermia experiments mice had been positioned on a heating pad at 42 °C for 1 h and had been allowed to relaxation in a single day19. Mice had been then handled by IP injection of both Alum (200 µL, 40 mg/mL) or MSU (200 µL, 10 mg/mL) for four h. A peritoneal lavage with 5 mL of PBS was carried out to gather cells and supernatants20. All the info, corresponding to 5 animals per group, had been collected alongside completely different experiments.

Circulation cytometry experiments

Collected peritoneal fluids had been centrifuged to pellet cells. The full variety of cells was evaluated and part of these cells had been stained with a PE rat anti-mouse Gr1 (551461) and an APC rat anti-mouse CD11b (553312) (BD Bioscience, Le Pont de Claix, France) for 20 min at four °C. After washing, cells had been analyzed with an LSRII stream cytometer (BD Biosciences) and analyzed utilizing Flowjo software program.

Mouse bone marrow-derived macrophages

C57BL/6 mice bone marrow cells had been remoted from tibias and femurs and cultured for six days on plastic plates in DMEM excessive glucose medium with ultraglutamine (Lonza) supplemented with 10% (vol/vol) fetal bovine serum (FBS; Lonza) within the presence of 50 ng/mL of M-CSF, in an environment of 95% air and 5% CO2 at 37 °C. Subsequently, floating cells had been eliminated and macrophage differentiation was noticed by fibroblast-like form modifications visualized with a Zeiss PrimoVert microscope. Differentiated cells had been then primed with LPS (100 ng/mL—Sigma-Aldrich) for 20 h and handled in OptiMEM by completely different inflammasome activators: ATP (5 mM) or Nigericin (40 µM) for 30 min, MSU (100 µg/mL) or Alum (100 µg/mL) for six h.

IL-1β detection

Murine IL-1β was detected utilizing the Mouse IL-1 beta/IL-1F2 DuoSet ELISA (DY401-05) equipment from R&D Methods in line with producer’s instruction. Briefly, 96-wells plates had been coated in a single day at room temperature with 100 μL of diluted IL-1β seize antibody at four µg/mL. After washing 3 times, wells had been blocked for 1 h. Then, 100 µL of samples or requirements had been incubated for two h at room temperature. After further three washes, 100 µL of diluted detection antibody at 500 ng/mL was added at room temperature for two h. Detection was carried out utilizing streptavidin-coupled HRP and its substrate with a microplate reader set at 450 nm. Focus was evaluated utilizing a normal curve.

Human IL-1β was detected utilizing the HEK-Blue™ IL-1β cells (Invivogen) in line with producer’s directions.

Supernatant precipitation

LPS-primed cells (1.5 × 106/500 µL) had been handled in OptiMEM with out FBS. The supernatants had been harvested by centrifugation for five min. at 400 × g and precipitated utilizing methanol (500 µL) and chloroform (150 µL). After centrifugation at most velocity for 10 min., the aqueous section (on the high) was discarded and 800 µL of methanol had been added. Samples had been centrifuged at most velocity for 10 min and the supernatants had been eliminated. Pellets (containing proteins) had been dried for 10 min. at 37 °C, combined with 40 µL of loading buffer (125 mM Tris-HCl [pH 6.8], 10% β-mercaptoethanol, four.6% SDS, 20% glycerol, and zero.003% bromophenol blue) and incubated at 95 °C for five min.

Western blotting

Complete-cell lysates had been ready by lysing cells in boiling buffer (1% SDS, 1 mM sodium vanadate, 10 mM Tris [pH 7.4]) within the presence of full protease inhibitor combination. Samples viscosity was decreased by sonication.

Complete-cell lysates or immunoprecipitated samples had been combined with loading buffer and separated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), and electroblotted to a nitrocellulose membrane (Amersham, GE Healthcare, Velizy-Villacoublay, France). After incubation for 1 h at RT with 5% nonfat milk in phosphate-buffered saline (PBS)–zero.1% Tween-20, membranes had been incubated in a single day with the first antibody diluted in PBS-milk-Tween, washed, incubated with the secondary antibody for 30 min at RT, and washed once more earlier than evaluation with a chemiluminescence detection equipment (Amersham, GE Healthcare). The next mouse mAbs had been used: anti–β-actin (A1978) from Sigma-Aldrich, anti-NLRP3 (AG-20B-0014), anti-human caspase-1 (AG-20B-0048) and anti-murine caspase-1 (AG-20B-0044) from Adipogen (COGER SAS, Paris, France). Rat pAbs anti-IL-1β (401-M) from R&D Methods and rabbit pAbs anti-ASC (AL177), anti-HSP27 (SPA-803), anti-HSP70 (SPA-812) and anti-HSP90 (SPS-711) from Enzo life sciences (Villeurbanne, France) had been additionally used. Secondary Abs HRP-conjugated polyclonal goat anti-mouse and swine anti-rabbit immunoglobulins (Jackson ImmunoResearch, Interchim, Montluçon, France) had been used.


Untreated or nigericin-treated cells (50.106) had been lysed in 1 mL lysis buffer (25 mM Hepes (pH8), 150 mM NaCl, zero.5% Triton X-100, 5 mM EDTA, 10% glycerol, 1 mM NaVO4, 20 mM NaF and CPIM) for 30 min on ice. After centrifugation at 14,000 × g at four °C for 30 min, supernatants had been precleared throughout 2 h at four °C within the presence of 30 μL of combined Sepharose 6B (6B100, Sigma-Aldrich) and protein G (17-0618-01, Amersham, GE Healthcare). After centrifugation at 1000 g for Three min the supernatant was incubated with 1 μg/mL of anti-HSP70 antibody (ADI-SPA-812, Enzo life sciences) and 40 μL of combined Sepharose at four °C for 20 h. The precipitates had been washed 4 occasions in lysis buffer, eluted in loading buffer and analyzed by immunoblotting.

In vitro caspase-1 activation assay

LPS-primed (or not) THP-1 cells had been pelleted and incubated in three volumes of hypotonic buffer (20 mM HEPES-KOH [pH 7.5], 10 mM KCl, 1.5 mM MgCl2, 1 mM Na EDTA, 1 mM Na EGTA and CPIM) for 15 min. on ice. Mobile membrane integrity was disrupted by passage by means of a G22 needle. Cell lysates had been centrifuged at most velocity for 20 min. at four °C and supernatants had been harvested. Inflammasome activation was induced by incubating 120 µg of the beforehand obtained extracts in a last quantity of 100 µL at 37 °C for 30 min and caspase-1 cleavage was monitored by Western blot.

Immunofluorescence (IF) and in situ proximity ligation assay (PLA)

Cells (150,000) had been seeded in 12 well-dishes containing a canopy glass (631–zero150, VWR Worldwide, Fontenay-sous-Bois, France) which was pretreated for 10 min with Poly-L-Lysin (P4707, Sigma Aldrich). The next day, cells had been handled with LPS at 100 ng/mL for 20 h after which with completely different inflammasome activators. Cells had been washed in PBS, fastened with four% PFA at four °C for 10 min and permeabilized utilizing a PBS, zero.5% BSA, zero.1% Saponin (47036, Sigma Aldrich) buffer for 20 min at RT. Samples had been incubated 2 h at RT with main antibodies or with Ig as a management.

For IF experiments, cells had been washed two occasions, and incubated with secondary Alexa488 or Alexa568 conjugated anti-mouse or anti-rabbit for 30 min at RT. For PLA experiments (Sigma-Aldrich DUO92007), after washing main antibodies, cells had been then incubated with the suitable probes (Sigma Aldrich DUO92004 and DUO92002) throughout one hour at 37 °C and washed two occasions. Probes had been then ligated for 30 min at 37 °C, washed two occasions in Buffer A and amplified utilizing the producer’s polymerase for 100 min at 37 °C in the dead of night.

For each experiments, cowl glasses had been mounted on a drop of Mounting Medium containing Dapi (Duo82040, Sigma Aldrich) for 15 min in the dead of night on a microscopy slide (045796, Dutscher, Brumath, France). Slides had been imaged utilizing a CDD outfitted upright microscope (Zeiss) and ×63, 1.4NA goal. Picture evaluation was carried out utilizing ImageJ software program.

The next antibodies had been used for IF and PLA: mouse anti-NLRP3 (1/500, AG-20B-0014, Adipogen), and anti-caspase-1 (AG-20B-0044, Adipogen), rabbit anti-ASC (1/1000, AL-177, Enzo Life Science), anti-HSP70 (1/200, AL-812, Enzo Life Science) goat anti-mouse Alexa488 (1/1000, A11029, Invitrogen), goat anti-rabbit Alexa568 (1/1000, A11036, Invitrogen, Life Applied sciences, Villebon sur Yvette, France), donkey anti-mouse Alexa568 (1/1000, A10037, Invitrogen).

Transient transfections

For the siRNA experiments, BMDMs had been transfected with the INTERFERin™ transfection reagent (Polyplus transfection, Illkirch, France) in line with producer’s directions. Briefly, 5.106 cells had been seeded in 145 mm petri dishes at some point earlier than transfection. Silencer® Choose siRNAs particular for the goal gene or Damaging siRNA management (Life Applied sciences) diluted in serum-free medium had been incubated with INTERFERin™ for 10 min at room temperature and added to the cells to a last focus of 1 nM. Twenty 4 hours after transfection, transfection medium was eliminated and the cells had been incubated with recent medium. The next siRNA had been used: Hspa1a (s101440), Hspa1b (s201488) or management (AM4611).

For overexpression experiments, BMDMs had been transfected with the Lipofectamine 2000 transfection reagent (Thermo Fisher Scientific) in line with producer directions. 5 million cells had been seeded in 145 mm petri dishes at some point earlier than transfections. The plasmids had been diluted in serum-free medium and had been incubated with Lipofectamine 2000 reagent for 20 min at room temperature and added to the cells at a last focus of two.5 µg/mL. Twenty 4 hours after transfection, the transfection medium was eliminated and the cells had been incubated with recent medium. HA-PCDNA3 empty vector and HA-PCDNA3-HSP70 had been kindly supplied by Aurélie DeThonel.

Statistical analyses

In vitro outcomes are proven as means ± s.d., in vivo outcomes are proven as means ± s.e.m. and comparisons of datasets had been carried out utilizing unpaired Scholar’s t take a look at (take a look at group in comparison with management group). Statistical calculations had been carried out utilizing GraphPad Prism 5. All P values had been two tailed.

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