PMID- 31244838 OWN - NLM STAT- MEDLINE DCOM- 20201013 LR - 20231104 IS - 1664-3224 (Electronic) IS - 1664-3224 (Linking) VI - 10 DP - 2019 TI - Mammalian Target of Rapamycin (mTOR) and the Proteasome Attenuates IL-1beta Expression in Primary Mouse Cardiac Fibroblasts. PG - 1285 LID - 10.3389/fimmu.2019.01285 [doi] LID - 1285 AB - Background: IL-1beta is a highly potent pro-inflammatory cytokine and its secretion is tightly regulated. Inactive pro-IL-1beta is transcribed in response to innate immune receptors activating NFkappaB. If tissue damage occurs, danger signals released from necrotic cells, such as ATP, can activate NLRP3-inflammasomes (multiprotein complexes consisting of NLRP3, ASC, and active caspase-1) which cleaves and activates pro-IL-1beta. NLRP3 activation also depends on NEK7 and mitochondrial ROS-production. Thus, IL-1beta secretion may be regulated at the level of each involved component. We have previously shown that NLRP3-dependent IL-1beta release can be induced in cardiac fibroblasts by pro-inflammatory stimuli. However, anti-inflammatory mechanisms targeting IL-1beta release in cardiac cells have not been investigated. mTOR is a key regulator of protein metabolism, including autophagy and proteasome activity. In this study we explored whether autophagy or proteasomal degradation are regulators of NLRP3 inflammasome activation and IL-1beta release from cardiac fibroblasts. Methods and Results: Serum starvation selectively reduced LPS/ATP-induced IL-1beta secretion from cardiac fibroblasts. However, no other inflammasome components, nor mitochondrial mass, were affected. The mTOR inhibitor rapamycin restored pro-IL-1beta protein levels as well as LPS/ATP-induced IL-1beta release from serum starved cells. However, neither serum starvation nor rapamycin induced autophagy in cardiac fibroblasts. Conversely, chloroquine and bafilomycin A (inhibitors of autophagy) and betulinic acid (a proteasome activator) effectively reduced LPS-induced pro-IL-1beta protein levels. Key findings were reinvestigated in human monocyte-derived macrophages. Conclusion: In cardiac fibroblasts, mTOR inhibition selectively favors pro-IL-1beta synthesis while proteasomal degradation and not autophagy is the major catabolic anti-inflammatory mechanism for degradation of this cytokine. FAU - Torp, May-Kristin AU - Torp MK AD - Division of Physiology, Department of Molecular Medicine, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway. AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. FAU - Yang, Kuan AU - Yang K AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. FAU - Ranheim, Trine AU - Ranheim T AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. FAU - Huso Lauritzen, Knut AU - Huso Lauritzen K AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. FAU - Alfsnes, Katrine AU - Alfsnes K AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. FAU - Vinge, Leif E AU - Vinge LE AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. AD - Department of Internal Medicine, Diakonhjemmet Hospital, Oslo, Norway. FAU - Aukrust, Pal AU - Aukrust P AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. AD - Section of Clinical Immunology and Infectious Diseases, Oslo University Hospital Rikshospitalet, Oslo, Norway. AD - Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway. FAU - Stenslokken, Kare-Olav AU - Stenslokken KO AD - Division of Physiology, Department of Molecular Medicine, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway. AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. FAU - Yndestad, Arne AU - Yndestad A AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. FAU - Sandanger, Oystein AU - Sandanger O AD - Centre for Heart Failure Research, University of Oslo, Oslo, Norway. AD - Research Institute of Internal Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway. AD - Section of Dermatology, Oslo University Hospital Rikshospitalet, Oslo, Norway. LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20190606 PL - Switzerland TA - Front Immunol JT - Frontiers in immunology JID - 101560960 RN - 0 (Biomarkers) RN - 0 (Cytokines) RN - 0 (Inflammasomes) RN - 0 (Interleukin-1beta) RN - 0 (Reactive Oxygen Species) RN - 886U3H6UFF (Chloroquine) RN - EC 2.7.11.1 (TOR Serine-Threonine Kinases) SB - IM MH - Animals MH - Biomarkers MH - Cell Line MH - Cells, Cultured MH - Chloroquine MH - Cytokines MH - Fibroblasts/*metabolism MH - *Gene Expression MH - Inflammasomes/*metabolism MH - Interleukin-1beta/*genetics/metabolism MH - Macrophages/immunology/metabolism MH - Mice MH - Mitochondria/metabolism MH - Proteolysis MH - Reactive Oxygen Species/metabolism MH - TOR Serine-Threonine Kinases/*metabolism PMC - PMC6563870 OTO - NOTNLM OT - IL-1 OT - NLRP3 OT - cardiac OT - chloroquine OT - fibroblasts OT - inflammasome OT - mTOR OT - proteasome EDAT- 2019/06/28 06:00 MHDA- 2020/10/21 06:00 PMCR- 2019/01/01 CRDT- 2019/06/28 06:00 PHST- 2018/11/08 00:00 [received] PHST- 2019/05/20 00:00 [accepted] PHST- 2019/06/28 06:00 [entrez] PHST- 2019/06/28 06:00 [pubmed] PHST- 2020/10/21 06:00 [medline] PHST- 2019/01/01 00:00 [pmc-release] AID - 10.3389/fimmu.2019.01285 [doi] PST - epublish SO - Front Immunol. 2019 Jun 6;10:1285. doi: 10.3389/fimmu.2019.01285. eCollection 2019.