1 2241 124 EPIGENETIC MODULATION IN PERIODONTITIS: INTERACTION OF ADIPONECTIN AND JMJD3-IRF4 AXIS IN MACROPHAGES. EMERGING EVIDENCE SUGGESTS AN IMPORTANT ROLE FOR EPIGENETIC MECHANISMS IN MODULATING SIGNALS DURING MACROPHAGE POLARIZATION AND INFLAMMATION. JMJD3, A JMJC FAMILY HISTONE DEMETHYLASE NECESSARY FOR M2 POLARIZATION IS ALSO REQUIRED FOR EFFECTIVE INDUCTION OF MULTIPLE M1 GENES BY LIPOPOLYSACCHARIDE (LPS). HOWEVER, THE EFFECTS OF JMJD3 TO INFLAMMATION IN THE CONTEXT OF OBESITY REMAINS UNKNOWN. TO ADDRESS THIS DEFICIENCY, WE FIRSTLY EXAMINED THE EXPRESSION OF JMJD3 IN MACROPHAGE ISOLATED FROM BONE MARROW AND ADIPOSE TISSUE OF DIET INDUCED OBESITY (DIO) MICE. THE RESULTS INDICATED THAT JMJD3 WAS DOWN-REGULATED IN OBESITY. ADIPONECTIN (APN), A FACTOR SECRETED BY ADIPOSE TISSUE WHICH IS DOWN-REGULATED IN OBESITY, FUNCTIONS TO SWITCH MACROPHAGE POLARIZATION FROM M1 TO M2, THEREBY ATTENUATING CHRONIC INFLAMMATION. INTRIGUINGLY, OUR RESULTS INDICATED THAT APN CONTRIBUTED TO JMJD3 UP-REGULATION, REDUCED MACROPHAGE INFILTRATION IN OBESE ADIPOSE TISSUE, AND ABOLISHED THE UP-REGULATION OF JMJD3 IN PERITONEAL MACROPHAGES ISOLATED FROM DIO MICE WHEN CHALLENGED WITH PORPHYROMONAS GINGIVALIS LPS (PG.LPS). TO ELUCIDATE THE INTERACTION OF APN AND JMJD3 INVOLVED IN MACROPHAGE TRANSFORMATION IN THE CONTEXT OF INFLAMMATION, WE DESIGNED THE LOSS AND GAIN-FUNCTION EXPERIMENTS OF APN IN VIVO WITH APN(-/-) MICE WITH EXPERIMENTAL PERIODONTITIS AND IN VITRO WITH MACROPHAGE ISOLATED FROM APN(-/-) MICE. FOR THE FIRST TIME, WE FOUND THAT APN CAN HELP TO REDUCE PERIODONTITIS-RELATED BONE LOSS, MODULATE JMJD3 AND IRF4 EXPRESSION, AND MACROPHAGE INFILTRATION. THEREFORE, IT CAN BE INFERRED THAT APN MAY CONTRIBUTE TO ANTI-INFLAMMATION MACROPHAGE POLARIZATION BY REGULATING JMJD3 EXPRESSION, WHICH PROVIDES A BASIS FOR MACROPHAGE-CENTERED EPIGENETIC THERAPEUTIC STRATEGIES. 2016 2 2026 35 EPIGENETIC CHANGES IN BONE MARROW PROGENITOR CELLS INFLUENCE THE INFLAMMATORY PHENOTYPE AND ALTER WOUND HEALING IN TYPE 2 DIABETES. CLASSICALLY ACTIVATED (M1) MACROPHAGES ARE KNOWN TO PLAY A ROLE IN THE DEVELOPMENT OF CHRONIC INFLAMMATION ASSOCIATED WITH IMPAIRED WOUND HEALING IN TYPE 2 DIABETES (T2D); HOWEVER, THE MECHANISM RESPONSIBLE FOR THE DOMINANT PROINFLAMMATORY (M1) MACROPHAGE PHENOTYPE IN T2D WOUNDS IS UNKNOWN. SINCE EPIGENETIC ENZYMES CAN DIRECT MACROPHAGE PHENOTYPES, WE ASSESSED THE ROLE OF HISTONE METHYLATION IN BONE MARROW (BM) STEM/PROGENITOR CELLS IN THE PROGRAMMING OF MACROPHAGES TOWARD A PROINFLAMMATORY PHENOTYPE. WE HAVE FOUND THAT A REPRESSIVE HISTONE METHYLATION MARK, H3K27ME3, IS DECREASED AT THE PROMOTER OF THE IL-12 GENE IN BM PROGENITORS AND THIS EPIGENETIC SIGNATURE IS PASSED DOWN TO WOUND MACROPHAGES IN A MURINE MODEL OF GLUCOSE INTOLERANCE (DIET-INDUCED OBESE). THESE EPIGENETICALLY "PREPROGRAMMED" MACROPHAGES RESULT IN POISED MACROPHAGES IN PERIPHERAL TISSUE AND NEGATIVELY IMPACT WOUND REPAIR. WE FOUND THAT IN DIABETIC CONDITIONS THE H3K27 DEMETHYLASE JMJD3 DRIVES IL-12 PRODUCTION IN MACROPHAGES AND THAT IL-12 PRODUCTION CAN BE MODULATED BY INHIBITING JMJD3. USING HUMAN T2D TISSUE AND MURINE MODELS, WE HAVE IDENTIFIED A PREVIOUSLY UNRECOGNIZED MECHANISM BY WHICH MACROPHAGES ARE PROGRAMMED TOWARD A PROINFLAMMATORY PHENOTYPE, ESTABLISHING A PATTERN OF UNRESTRAINED INFLAMMATION ASSOCIATED WITH NONHEALING WOUNDS. HENCE, HISTONE DEMETHYLASE INHIBITOR-BASED THERAPY MAY REPRESENT A NOVEL TREATMENT OPTION FOR DIABETIC WOUNDS. 2015 3 875 29 CHRONIC AND TRANSIENT HYPERGLYCEMIA INDUCES CHANGES IN THE EXPRESSION PATTERNS OF IL6 AND ADIPOQ GENES AND THEIR ASSOCIATED EPIGENETIC MODIFICATIONS IN DIFFERENTIATING HUMAN VISCERAL ADIPOCYTES. ADIPOKINES SECRETED BY HYPERTROPHIC VISCERAL ADIPOSE TISSUE (VAT) INSTIGATE LOW-GRADE INFLAMMATION, FOLLOWED BY HYPERGLYCEMIA (HG)-RELATED METABOLIC DISORDERS. THE LATTER MAY DEVELOP WITH THE PARTICIPATION OF EPIGENETIC MODIFICATIONS. OUR AIM WAS TO ASSESS HOW HG INFLUENCES SELECTED EPIGENETIC MODIFICATIONS AND THE EXPRESSION OF INTERLEUKIN 6 (IL-6) AND ADIPONECTIN (APN; GENE SYMBOL ADIPOQ) DURING THE ADIPOGENESIS OF HUMAN VISCERAL PREADIPOCYTES (HPA-V). ADIPOCYTES (ADS) WERE CHRONICALLY OR TRANSIENTLY HG-TREATED DURING THREE STAGES OF ADIPOGENESIS (PROLIFERATION, DIFFERENTIATION, MATURATION). WE MEASURED ADIPOKINE MRNA, PROTEIN, PROVEN OR PREDICTED MICRORNA EXPRESSION (RT-QPCR AND ELISA), AND ENRICHMENT OF H3K9/14AC, H3K4ME3, AND H3K9ME3 AT GENE PROMOTER REGIONS (CHROMATIN IMMUNOPRECIPITATION). IN CHRONIC HG, WE DETECTED DIFFERENT EXPRESSION PATTERNS OF THE STUDIED ADIPOKINES AT THE MRNA AND PROTEIN LEVELS. CHRONIC AND TRANSIENT HG-INDUCED CHANGES IN MIRNA (MIR-26A-5P, MIR-26B-5P, LET-7D-5P, LET-7E-5P, MIR-365A-3P, MIR-146A-5P) WERE MOSTLY CONVERGENT TO ALTERED IL-6 TRANSCRIPTION. ALTERATIONS IN HISTONE MARKS AT THE IL6 PROMOTER WERE ALSO IN AGREEMENT WITH IL-6 MRNA. THE OPEN CHROMATIN MARKS AT THE ADIPOQ PROMOTER MOSTLY REFLECTED THE APN TRANSCRIPTION DURING NG ADIPOGENESIS, WHILE, IN THE DIFFERENTIATION STAGE, HG-INDUCED CHANGES IN ALL STUDIED MARKS WERE IN LINE WITH APN MRNA LEVELS. IN SUMMARY, HG DYSREGULATED ADIPOKINE EXPRESSION, PROMOTING INFLAMMATION. EPIGENETIC CHANGES COEXISTED WITH ALTERED EXPRESSION OF ADIPOKINES, ESPECIALLY FOR IL-6; THEREFORE, EPIGENETIC MARKS INDUCED BY TRANSIENT HG MAY ACT AS EPI-MEMORY IN ADS. SUCH CHANGES IN THE EPIGENOME AND EXPRESSION OF ADIPOKINES COULD BE INSTRUMENTAL IN THE DEVELOPMENT OF INFLAMMATION AND METABOLIC DEREGULATION OF VAT. 2021 4 6176 29 THE HISTONE H3 LYSINE-27 DEMETHYLASE JMJD3 LINKS INFLAMMATION TO INHIBITION OF POLYCOMB-MEDIATED GENE SILENCING. EPIGENETIC CHROMATIN MARKS RESTRICT THE ABILITY OF DIFFERENTIATED CELLS TO CHANGE GENE EXPRESSION PROGRAMS IN RESPONSE TO ENVIRONMENTAL CUES AND TO TRANSDIFFERENTIATE. POLYCOMB GROUP (PCG) PROTEINS MEDIATE GENE SILENCING AND REPRESS TRANSDIFFERENTIATION IN A MANNER DEPENDENT ON HISTONE H3 LYSINE 27 TRIMETHYLATION (H3K27ME3). HOWEVER, MACROPHAGES MIGRATED INTO INFLAMED TISSUES CAN TRANSDIFFERENTIATE, BUT IT IS UNKNOWN WHETHER INFLAMMATION ALTERS PCG-DEPENDENT SILENCING. HERE WE SHOW THAT THE JMJC-DOMAIN PROTEIN JMJD3 IS A H3K27ME DEMETHYLASE EXPRESSED IN MACROPHAGES IN RESPONSE TO BACTERIAL PRODUCTS AND INFLAMMATORY CYTOKINES. JMJD3 BINDS PCG TARGET GENES AND REGULATES THEIR H3K27ME3 LEVELS AND TRANSCRIPTIONAL ACTIVITY. THE DISCOVERY OF AN INDUCIBLE ENZYME THAT ERASES A HISTONE MARK CONTROLLING DIFFERENTIATION AND CELL IDENTITY PROVIDES A LINK BETWEEN INFLAMMATION AND REPROGRAMMING OF THE EPIGENOME, WHICH COULD BE THE BASIS FOR MACROPHAGE PLASTICITY AND MIGHT EXPLAIN THE DIFFERENTIATION ABNORMALITIES IN CHRONIC INFLAMMATION. 2007 5 2067 39 EPIGENETIC CONTROL OF MACROPHAGE SHAPE TRANSITION TOWARDS AN ATYPICAL ELONGATED PHENOTYPE BY HISTONE DEACETYLASE ACTIVITY. INFLAMMATORY CHRONIC PATHOLOGIES ARE COMPLEX PROCESSES CHARACTERIZED BY AN IMBALANCE BETWEEN THE RESOLUTION OF THE INFLAMMATORY PHASE AND THE ESTABLISHMENT OF TISSUE REPAIR. THE MAIN PLAYERS IN THESE INFLAMMATORY PATHOLOGIES ARE BONE MARROW DERIVED MONOCYTES (BMDMS). HOWEVER, HOW MONOCYTE DIFFERENTIATION IS MODULATED TO GIVE RISE TO SPECIFIC MACROPHAGE SUBPOPULATIONS (M1 OR M2) THAT MAY EITHER MAINTAIN THE CHRONIC INFLAMMATORY PROCESS OR LEAD TO WOUND HEALING IS STILL UNCLEAR. CONSIDERING THAT INHIBITORS OF HISTONE DEACETYLASE (HDAC) HAVE AN ANTI-INFLAMMATORY ACTIVITY, WE ASKED WHETHER THIS ENZYME WOULD PLAY A ROLE ON MONOCYTE DIFFERENTIATION INTO M1 OR M2 PHENOTYPE AND IN THE CELL SHAPE TRANSITION THAT FOLLOWS. WE THEN INDUCED MURINE BONE MARROW PROGENITORS INTO MONOCYTE/MACROPHAGE DIFFERENTIATION PATHWAY USING MEDIA CONTAINING GM-CSF AND THE HDAC BLOCKER, TRICHOSTATIN A (TSA). WE FOUND THAT THE PHARMACOLOGICAL INHIBITION OF HDAC ACTIVITY LED TO A SHAPE TRANSITION FROM THE TYPICAL MACROPHAGE PANCAKE-LIKE SHAPE INTO AN ELONGATED MORPHOLOGY, WHICH WAS CORRELATED TO A MIXED M1/M2 PROFILE OF CYTOKINE AND CHEMOKINE SECRETION. OUR RESULTS PRESENT, FOR THE FIRST TIME, THAT HDAC ACTIVITY ACTS AS A REGULATOR OF MACROPHAGE DIFFERENTIATION IN THE ABSENCE OF LYMPHOCYTE STIMULI. WE PROPOSE THAT HDAC ACTIVITY DOWN REGULATES MACROPHAGE PLASTICITY FAVORING THE PRO-INFLAMMATORY PHENOTYPE. 2015 6 5114 42 PORPHYROMONAS GINGIVALIS LIPOPOLYSACCHARIDE STIMULATION IN HUMAN PERIODONTAL LIGAMENT STEM CELLS: ROLE OF EPIGENETIC MODIFICATIONS TO THE INFLAMMATION. PERIODONTITIS IS A CHRONIC ORAL INFLAMMATORY DISEASE PRODUCED BY BACTERIA. GINGIVAL RETRACTION AND BONE AND CONNECTIVE TISSUES RESORPTION ARE THE HALLMARKS OF THIS DISEASE. CHRONIC PERIODONTITIS MAY CONTRIBUTE TO THE RISK OF ONSET OR PROGRESSION OF NEUROINFLAMMATORY PATHOLOGICAL CONDITIONS, SUCH AS ALZHEIMER'S DISEASE. THE MAIN GOAL OF THE PRESENT STUDY WAS TO INVESTIGATE IF THE ROLE OF EPIGENETIC MODULATIONS IS INVOLVED IN PERIODONTITIS USING HUMAN PERIODONTAL LIGAMENT STEM CELLS (HPDLSCS) AS AN IN VITRO MODEL SYSTEM. HPDLSCS WERE TREATED WITH LIPOPOLYSACCHARIDE OF PORPHYROMONAS GINGIVALIS AND THE EXPRESSION OF PROTEINS ASSOCIATED WITH DNA METHYLATION AND HISTONE ACETYLATION, SUCH AS DNMT1 AND P300, RESPECTIVELY, AND INFLAMMATORY TRANSCRIPTION FACTOR NF-KB, WERE EXAMINED. IMMUNOFLUORESCENCE, WESTERN BLOT AND NEXT GENERATION SEQUENCING RESULTS DEMONSTRATED THAT P. GINGIVALIS LIPOPOLYSACCHARIDE SIGNIFICANTLY REDUCED DNA METHYLASE DNMT1, WHILE IT MARKEDLY UPREGULATED THE LEVEL OF HISTONE ACETYLTRANSFERASE P300 AND NF-KB IN HPDLSCS. OUR RESULTS SHOWED THAT P. GINGIVALIS LIPOPOLYSACCHARIDE MARKEDLY REGULATE THE GENES INVOLVED IN EPIGENETIC MECHANISM, WHICH MAY RESULT IN INFLAMMATION INDUCTION. WE PROPOSE THAT P. GINGIVALIS LIPOPOLYSACCHARIDE-TREATED HPDLSCS COULD BE A POTENTIAL IN VITRO MODEL SYSTEM TO STUDY EPIGENETICS MODULATIONS ASSOCIATED WITH PERIODONTITIS, WHICH MIGHT BE HELPFUL TO IDENTIFY NOVEL BIOMARKERS LINKED TO THIS ORAL INFLAMMATORY DISEASE. 2017 7 4391 35 MODERATE EXERCISE INDUCES TRAINED IMMUNITY IN MACROPHAGES. DESPITE ITS IMPORTANCE IN PROTECTING THE HOST FROM INFECTIONS AND INJURY, EXCESSIVE INFLAMMATION MAY LEAD TO SERIOUS HUMAN DISEASES INCLUDING AUTOIMMUNE DISORDERS, CARDIOVASCULAR DISEASES, DIABETES, AND CANCER. EXERCISE IS A KNOWN IMMUNOMODULATOR; HOWEVER, WHETHER EXERCISE CAUSES LONG-TERM CHANGES IN INFLAMMATORY RESPONSES AND HOW THESE CHANGES OCCUR ARE LACKING. HERE, WE SHOW THAT CHRONIC MODERATE-INTENSITY TRAINING OF MICE LEADS TO PERSISTENT METABOLIC REWIRING AND CHANGES TO CHROMATIN ACCESSIBILITY IN BONE MARROW-DERIVED MACROPHAGES (BMDMS), WHICH, IN TURN, TEMPERS THEIR INFLAMMATORY RESPONSES. WE SHOW THAT BMDMS FROM EXERCISED MICE EXHIBITED A DECREASE IN LIPOPOLYSACCHARIDE (LPS)-INDUCED NF-KAPPAB ACTIVATION AND PROINFLAMMATORY GENE EXPRESSION ALONG WITH AN INCREASE IN M2-LIKE-ASSOCIATED GENES WHEN COMPARED WITH BMDMS FROM SEDENTARY MICE. THIS WAS ASSOCIATED WITH IMPROVED MITOCHONDRIAL QUALITY AND INCREASED RELIANCE ON OXIDATIVE PHOSPHORYLATION ACCOMPANIED WITH REDUCED MITOCHONDRIAL REACTIVE OXYGEN SPECIES (ROS) PRODUCTION. MECHANISTICALLY, ASSAY FOR TRANSPOSASE-ACCESSIBLE CHROMATIN (ATAC)-SEQ ANALYSIS SHOWED CHANGES IN CHROMATIN ACCESSIBILITY OF GENES ASSOCIATED WITH INFLAMMATORY AND METABOLIC PATHWAYS. OVERALL, OUR DATA SUGGEST THAT CHRONIC MODERATE EXERCISE CAN INFLUENCE THE INFLAMMATORY RESPONSES OF MACROPHAGES BY REPROGRAMMING THEIR METABOLIC AND EPIGENETIC LANDSCAPE.NEW & NOTEWORTHY IN THIS STUDY, WE EXPLAIN HOW LONG-TERM MODERATE EXERCISE TRAINING CAN REDUCE INFLAMMATION IN MOUSE MACROPHAGES BY REPROGRAMMING THE WAY THEY SENSE AND RESPOND TO THE PRESENCE OF PATHOGENS. WE COMPLETED A THOROUGH ANALYSIS AND SHOWED THAT THESE CHANGES PERSIST IN MACROPHAGES BECAUSE EXERCISE IMPROVES THE ABILITY OF CELLS TO UTILIZE OXYGEN WITHOUT PRODUCING DAMAGING COMPOUNDS, AND CHANGES THE WAY THEY ACCESS THEIR DNA. 2023 8 2370 29 EPIGENETIC REGULATION OF THE ALTERNATIVELY ACTIVATED MACROPHAGE PHENOTYPE. ALTERNATIVELY ACTIVATED (M2) MACROPHAGES PLAY CRITICAL ROLES IN DIVERSE CHRONIC DISEASES, INCLUDING PARASITE INFECTIONS, CANCER, AND ALLERGIC RESPONSES. HOWEVER, LITTLE IS KNOWN ABOUT THE ACQUISITION AND MAINTENANCE OF THEIR PHENOTYPE. WE REPORT THAT M2-MACROPHAGE MARKER GENES ARE EPIGENETICALLY REGULATED BY RECIPROCAL CHANGES IN HISTONE H3 LYSINE-4 (H3K4) AND HISTONE H3 LYSINE-27 (H3K27) METHYLATION; AND THE LATTER METHYLATION MARKS ARE REMOVED BY THE H3K27 DEMETHYLASE JUMONJI DOMAIN CONTAINING 3 (JMJD3). WE FOUND THAT CONTINUOUS INTERLEUKIN-4 (IL-4) TREATMENT LEADS TO DECREASED H3K27 METHYLATION, AT THE PROMOTER OF M2 MARKER GENES, AND A CONCOMITANT INCREASE IN JMJD3 EXPRESSION. FURTHERMORE, WE DEMONSTRATE THAT IL-4-DEPENDENT JMJD3 EXPRESSION IS MEDIATED BY STAT6, A MAJOR TRANSCRIPTION FACTOR OF IL-4-MEDIATED SIGNALING. AFTER IL-4 STIMULATION, ACTIVATED STAT6 IS INCREASED AND BINDS TO CONSENSUS SITES AT THE JMJD3 PROMOTER. INCREASED JMJD3 CONTRIBUTES TO THE DECREASE OF H3K27 DIMETHYLATION AND TRIMETHYLATION (H3K27ME2/3) MARKS AS WELL AS THE TRANSCRIPTIONAL ACTIVATION OF SPECIFIC M2 MARKER GENES. THE DECREASE IN H3K27ME2/3 AND INCREASE IN JMJD3 RECRUITMENT WERE CONFIRMED BY IN VIVO STUDIES USING A SCHISTOSOMA MANSONI EGG-CHALLENGED MOUSE MODEL, A WELL-STUDIED SYSTEM KNOWN TO SUPPORT AN M2 PHENOTYPE. COLLECTIVELY, THESE DATA INDICATE THAT CHROMATIN REMODELING IS MECHANISTICALLY IMPORTANT IN THE ACQUISITION OF THE M2-MACROPHAGE PHENOTYPE. 2009 9 2247 28 EPIGENETIC MODULATION OF MACROPHAGE POLARIZATION PREVENTS LUMBAR DISC DEGENERATION. INFLAMMATION PLAYS AN ESSENTIAL ROLE IN THE DEVELOPMENT OF LUMBAR DISC DEGENERATION (LDD), ALTHOUGH THE EXACT EFFECTS OF MACROPHAGE SUBTYPES ON LDD REMAIN UNCLEAR. BASED ON PREVIOUS STUDIES, WE HYPOTHESIZED THAT M2-POLARIZATION OF LOCAL MACROPHAGES AND SIMULTANEOUS SUPPRESSION OF THEIR PRODUCTION OF FIBROTIC TRANSFORMING GROWTH FACTOR BETA 1 (TGFBETA1) COULD INHIBIT PROGRESSION OF LDD. THUS, WE APPLIED AN ORTHOTOPIC INJECTION OF ADENO-ASSOCIATED VIRUS (AAV) CARRYING SHRNA FOR DNA METHYLTRANSFERASE 1 (DNMT1) AND/OR SHRNA FOR TGFBETA1 UNDER A MACROPHAGE-SPECIFIC CD68 PROMOTER TO SPECIFICALLY TARGET LOCAL MACROPHAGES IN A MOUSE MODEL FOR LDD. WE FOUND THAT SHDNMT1 SIGNIFICANTLY REDUCED LEVELS OF THE PRO-INFLAMMATORY CYTOKINES TNFALPHA, IL-1BETA AND IL-6, SIGNIFICANTLY INCREASED LEVELS OF THE ANTI-INFLAMMATORY CYTOKINES IL-4 AND IL-10, SIGNIFICANTLY INCREASED M2 MACROPHAGE POLARIZATION, SIGNIFICANTLY REDUCED CELL APOPTOSIS IN THE DISC DEGENERATION ZONE AND SIGNIFICANTLY REDUCED LDD-ASSOCIATED PAIN. THE ANTI-APOPTOTIC AND ANTI-PAIN EFFECTS WERE FURTHER STRENGTHENED BY CO-APPLICATION OF SHTGFBETA1. TOGETHER, THESE DATA SUGGEST THAT M2 POLARIZATION OF MACROPHAGES INDUCED BY BOTH EPIGENETIC MODULATION AND SUPPRESSED PRODUCTION AND RELEASE OF TGFBETA1 FROM POLARIZED M2 MACROPHAGES, MAY HAVE A DEMONSTRABLE THERAPEUTIC EFFECT ON LDD. 2020 10 3436 33 HYPERGLYCEMIC MEMORY OF INNATE IMMUNE CELLS PROMOTES IN VITRO PROINFLAMMATORY RESPONSES OF HUMAN MONOCYTES AND MURINE MACROPHAGES. IT HAS BEEN WELL ESTABLISHED THAT THE PRESENCE OF DIABETES IS ACCOMPANIED BY A CHRONIC INFLAMMATORY STATE PROMOTING VARIOUS DIABETES-ASSOCIATED COMPLICATIONS. ONE POTENTIAL DRIVER OF THIS ENHANCED INFLAMMATORY STATE IN PATIENTS WITH DIABETES IS HYPERGLYCEMIA. EVEN AFTER BLOOD GLUCOSE CONTROL IS ACHIEVED, DIABETES-ASSOCIATED COMPLICATIONS PERSIST, SUGGESTING THE PRESENCE OF A "HYPERGLYCEMIC MEMORY." INNATE IMMUNE CELLS, CRITICALLY INVOLVED IN VARIOUS COMPLICATIONS ASSOCIATED WITH DIABETES, CAN BUILD NONSPECIFIC, IMMUNOLOGICAL MEMORY (TRAINED IMMUNITY) VIA EPIGENETIC REGULATION. WE EXAMINE THE POTENTIAL INVOLVEMENT OF HYPERGLYCEMIA-INDUCED TRAINED IMMUNITY IN PROMOTING INFLAMMATION. OUR RESULTS SHOW THAT HYPERGLYCEMIA INDUCES A TRAINED PHENOTYPE IN VIVO IN MICE AND IN VITRO IN HUMAN MONOCYTES, REPRESENTATIVE BY AN INCREASED TNF-ALPHA SECRETION AFTER EX VIVO STIMULATION WITH LPS. THESE EFFECTS WERE LARGELY MEDIATED BY EPIGENETIC CHANGES CONTROLLED BY THE MIXED LINEAGE LEUKEMIA (MLL) FAMILY BECAUSE TREATMENT WITH THE MLL INHIBITOR MENIN-MLL DURING THE PROCESS OF TRAINED IMMUNITY ACQUISITION REPRESSED THE PROINFLAMMATORY PHENOTYPE. COLLECTIVELY, OUR RESULTS IDENTIFY A NOVEL LINK BETWEEN HYPERGLYCEMIA AND INFLAMMATION IN INNATE IMMUNE CELLS THAT MIGHT EXPLAIN THE INCREASED PROINFLAMMATORY STATE DURING DIABETES POTENTIALLY CONTRIBUTING TO THE DEVELOPMENT OF VARIOUS DIABETES-ASSOCIATED COMPLICATIONS. 2021 11 6471 36 TNF-ALPHA REGULATES DIABETIC MACROPHAGE FUNCTION THROUGH THE HISTONE ACETYLTRANSFERASE MOF. A CRITICAL COMPONENT OF WOUND HEALING IS THE TRANSITION FROM THE INFLAMMATORY PHASE TO THE PROLIFERATION PHASE TO INITIATE HEALING AND REMODELING OF THE WOUND. MACROPHAGES ARE CRITICAL FOR THE INITIATION AND RESOLUTION OF THE INFLAMMATORY PHASE DURING WOUND REPAIR. IN DIABETES, MACROPHAGES DISPLAY A SUSTAINED INFLAMMATORY PHENOTYPE IN LATE WOUND HEALING CHARACTERIZED BY ELEVATED PRODUCTION OF INFLAMMATORY CYTOKINES, SUCH AS TNF-ALPHA. PREVIOUS STUDIES HAVE SHOWN THAT AN ALTERED EPIGENETIC PROGRAM DIRECTS DIABETIC MACROPHAGES TOWARD A PROINFLAMMATORY PHENOTYPE, CONTRIBUTING TO A SUSTAINED INFLAMMATORY PHASE. MALES ABSENT ON THE FIRST (MOF) IS A HISTONE ACETYLTRANSFERASE (HAT) THAT HAS BEEN SHOWN BE A COACTIVATOR OF TNF-ALPHA SIGNALING AND PROMOTE NF-KAPPAB-MEDIATED GENE TRANSCRIPTION IN PROSTATE CANCER CELL LINES. BASED ON MOF'S ROLE IN TNF-ALPHA/NF-KAPPAB-MEDIATED GENE EXPRESSION, WE HYPOTHESIZED THAT MOF INFLUENCES MACROPHAGE-MEDIATED INFLAMMATION DURING WOUND REPAIR. WE USED MYELOID-SPECIFIC MOF-KNOCKOUT (LYZ2CRE MOFFL/FL) AND DIET-INDUCED OBESE (DIO) MICE TO DETERMINE THE FUNCTION OF MOF IN DIABETIC WOUND HEALING. MOF-DEFICIENT MICE EXHIBITED REDUCED INFLAMMATORY CYTOKINE GENE EXPRESSION. FURTHERMORE, WE FOUND THAT WOUND MACROPHAGES FROM DIO MICE HAD ELEVATED MOF LEVELS AND HIGHER LEVELS OF ACETYLATED HISTONE H4K16, MOF'S PRIMARY SUBSTRATE OF HAT ACTIVITY, ON THE PROMOTERS OF INFLAMMATORY GENES. WE FURTHER IDENTIFIED THAT MOF EXPRESSION COULD BE STIMULATED BY TNF-ALPHA AND THAT TREATMENT WITH ETANERCEPT, AN FDA-APPROVED TNF-ALPHA INHIBITOR, REDUCED MOF LEVELS AND IMPROVED WOUND HEALING IN DIO MICE. THIS REPORT IS THE FIRST TO OUR KNOWLEDGE TO DEFINE AN IMPORTANT ROLE FOR MOF IN REGULATING MACROPHAGE-MEDIATED INFLAMMATION IN WOUND REPAIR AND IDENTIFIES TNF-ALPHA INHIBITION AS A POTENTIAL THERAPY FOR THE TREATMENT OF CHRONIC INFLAMMATION IN DIABETIC WOUNDS. 2020 12 2228 34 EPIGENETIC MODIFICATIONS OF HISTONES IN PERIODONTAL DISEASE. PERIODONTITIS IS A CHRONIC INFECTIOUS DISEASE DRIVEN BY DYSBIOSIS, AN IMBALANCE BETWEEN COMMENSAL BACTERIA AND THE HOST ORGANISM. PERIODONTITIS IS A LEADING CAUSE OF TOOTH LOSS IN ADULTS AND OCCURS IN ABOUT 50% OF THE US POPULATION. IN ADDITION TO THE CLINICAL CHALLENGES ASSOCIATED WITH TREATING PERIODONTITIS, THE PROGRESSION AND CHRONIC NATURE OF THIS DISEASE SERIOUSLY AFFECT HUMAN HEALTH. EMERGING EVIDENCE SUGGESTS THAT PERIODONTITIS IS ASSOCIATED WITH MECHANISMS BEYOND BACTERIA-INDUCED PROTEIN AND TISSUE DEGRADATION. HERE, WE HYPOTHESIZE THAT BACTERIA ARE ABLE TO INDUCE EPIGENETIC MODIFICATIONS IN ORAL EPITHELIAL CELLS MEDIATED BY HISTONE MODIFICATIONS. IN THIS STUDY, WE FOUND THAT DYSBIOSIS IN VIVO LED TO EPIGENETIC MODIFICATIONS, INCLUDING ACETYLATION OF HISTONES AND DOWNREGULATION OF DNA METHYLTRANSFERASE 1. IN ADDITION, IN VITRO EXPOSURE OF ORAL EPITHELIAL CELLS TO LIPOPOLYSACCHARIDES RESULTED IN HISTONE MODIFICATIONS, ACTIVATION OF TRANSCRIPTIONAL COACTIVATORS, SUCH AS P300/CBP, AND ACCUMULATION OF NUCLEAR FACTOR-KAPPAB (NF-KAPPAB). GIVEN THAT ORAL EPITHELIAL CELLS ARE THE FIRST LINE OF DEFENSE FOR THE PERIODONTIUM AGAINST BACTERIA, WE ALSO EVALUATED WHETHER ACTIVATION OF PATHOGEN RECOGNITION RECEPTORS INDUCED HISTONE MODIFICATIONS. WE FOUND THAT ACTIVATION OF THE TOLL-LIKE RECEPTORS 1, 2, AND 4 AND THE NUCLEOTIDE-BINDING OLIGOMERIZATION DOMAIN PROTEIN 1 INDUCED HISTONE ACETYLATION IN ORAL EPITHELIAL CELLS. OUR FINDINGS CORROBORATE THE EMERGING CONCEPT THAT EPIGENETIC MODIFICATIONS PLAY A ROLE IN THE DEVELOPMENT OF PERIODONTITIS. 2016 13 2641 33 EPIGENOMIC AND TRANSCRIPTOMIC ANALYSES REVEAL DIFFERENCES BETWEEN LOW-GRADE INFLAMMATION AND SEVERE EXHAUSTION IN LPS-CHALLENGED MURINE MONOCYTES. EMERGING STUDIES SUGGEST THAT MONOCYTES CAN BE TRAINED BY BACTERIAL ENDOTOXIN TO ADOPT DISTINCT MEMORY STATES RANGING FROM LOW-GRADE INFLAMMATION TO IMMUNE EXHAUSTION. WHILE LOW-GRADE INFLAMMATION MAY CONTRIBUTE TO THE PATHOGENESIS OF CHRONIC DISEASES, EXHAUSTED MONOCYTES WITH PATHOGENIC AND IMMUNE-SUPPRESSIVE CHARACTERISTICS MAY UNDERLIE THE PATHOGENESIS OF POLYMICROBIAL SEPSIS INCLUDING COVID-19. HOWEVER, DETAILED PROCESSES BY WHICH THE DYNAMIC ADAPTION OF MONOCYTES OCCUR REMAIN POORLY UNDERSTOOD. HERE WE EXPOSED MURINE BONE-MARROW DERIVED MONOCYTES TO CHRONIC LIPOPOLYSACCHARIDE (LPS) STIMULATION AT LOW-DOSE OR HIGH-DOSE, AS WELL AS A PBS CONTROL. THE CELLS WERE PROFILED FOR GENOME-WIDE H3K27AC MODIFICATION AND GENE EXPRESSION. THE GENE EXPRESSION OF TRAM-DEFICIENT AND IRAK-M-DEFICIENT MONOCYTES WITH LPS EXPOSURE WAS ALSO ANALYZED. WE DISCOVER THAT LOW-GRADE INFLAMMATION PREFERENTIALLY UTILIZES THE TRAM-DEPENDENT PATHWAY OF TLR4 SIGNALING, AND INDUCES THE EXPRESSION OF INTERFERON RESPONSE GENES. IN CONTRAST, HIGH DOSE LPS UNIQUELY UPREGULATES EXHAUSTION SIGNATURES WITH METABOLIC AND PROLIFERATIVE PATHWAYS. THE EXTENSIVE DIFFERENCES IN THE EPIGENOMIC LANDSCAPE BETWEEN LOW-DOSE AND HIGH-DOSE CONDITIONS SUGGEST THE IMPORTANCE OF EPIGENETIC REGULATIONS IN DRIVING DIFFERENTIAL RESPONSES. OUR DATA PROVIDE POTENTIAL TARGETS FOR FUTURE MECHANISTIC OR THERAPEUTIC STUDIES. 2022 14 3342 36 HISTONE DEACETYLASE9 REPRESENTS THE EPIGENETIC PROMOTION OF M1 MACROPHAGE POLARIZATION AND INFLAMMATORY RESPONSE VIA TLR4 REGULATION. ATHEROSCLEROSIS IS A CHRONIC INFLAMMATORY RESPONSE MEDIATED BY VARIOUS FACTORS, WHERE EPIGENETIC REGULATION INVOLVING HISTONE DEACETYLATION IS ENVISAGED TO MODULATE THE EXPRESSION OF RELATED PROTEINS BY REGULATING THE BINDING OF TRANSCRIPTION FACTORS TO DNA, THEREBY INFLUENCING THE DEVELOPMENT OF ATHEROSCLEROSIS. THE MECHANISM OF ATHEROSCLEROSIS BY HISTONE DEACETYLATION IS PARTLY KNOWN; HENCE, THIS PROJECT AIMED AT INVESTIGATING THE ROLE OF HISTONE DEACETYLASE 9 (HDAC9) IN ATHEROSCLEROSIS. FOR THIS PURPOSE, SERUM WAS SEPARATED FROM BLOOD SAMPLES FOLLOWING CLOTTING AND CENTRIFUGATION FROM ATHEROSCLEROTIC AND HEALTHY PATIENTS (N = 40 EACH), AND THEN, VARIOUS TESTS WERE PERFORMED. THE RESULTS INDICATED THAT TOLL-LIKE RECEPTOR 4 (TLR4) WAS NOT ONLY POSITIVELY CORRELATED TO THE HDAC9 GENE, BUT WAS ALSO UPREGULATED IN ATHEROSCLEROSIS, WHERE IT WAS ALSO SIGNIFICANTLY UPREGULATED IN THE ATHEROSCLEROSIS CELL MODEL OF OXIDIZED LOW-DENSITY LIPOPROTEIN-INDUCED MACROPHAGES. CONVERSELY, THE TLR4 WAS SIGNIFICANTLY DOWNREGULATED IN INSTANCES OF LOSS OF HDAC9 FUNCTION, CEMENTING THE BRIDGING RELATIONSHIP BETWEEN HDAC9 AND MACROPHAGE POLARIZATION, WHERE THE HDAC9 WAS FOUND TO UPREGULATE M1 MACROPHAGE POLARIZATION WHICH TRANSLATED INTO THE RELEASE OF HIGHER CONTENT OF PROINFLAMMATORY CYTOKINES SUCH AS INTERLEUKIN-1BETA (IL-1BETA) AND TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA), WHICH TEND TO SIGNIFICANTLY DECREASE FOLLOWING THE DELETION OF TLR4. HENCE, THIS STUDY REPORTS NOVEL RELATION BETWEEN EPIGENETIC CONTROL AND ATHEROSCLEROSIS, WHICH COULD PARTLY BE EXPLAINED BY HISTONE DEACETYLATION. 2022 15 5975 31 TET1 IS AN IMPORTANT TRANSCRIPTIONAL ACTIVATOR OF TNFALPHA EXPRESSION IN MACROPHAGES. ACTIVATION OF MACROPHAGES AND OVEREXPRESSION OF TNFALPHA IS ASSOCIATED WITH THE PATHOGENESIS OF CHRONIC INFLAMMATORY DISEASES. HOWEVER, THE MECHANISMS LEADING TO TNFALPHA OVEREXPRESSION ARE STILL UNKNOWN. 5-METHYLOCYTOSINE (5-MC) IS AN EPIGENETIC MODIFICATION THAT IS ASSOCIATED WITH SILENCED GENES. RECENT STUDIES SHOWED THAT IT IS CONVERTED TO 5-HYDROXYLMETHYLOCYTOSINE (5-HMC) AND REACTIVATES GENE EXPRESSION THROUGH THE ACTION OF THE FAMILY OF TEN-ELEVEN-TRANSLOCATION (TET1-3) ENZYMES. IN THIS STUDY, WE SHOW THAT 5-HMC LEVELS ARE INCREASED GLOBALLY AND SPECIFICALLY IN THE TNFALPHA PROMOTER DURING THE DIFFERENTIATION OF MONOCYTES TO MACROPHAGES. IN ADDITION, THE LEVELS OF 5-HMC ARE INCREASED UPON LPS STIMULATION OF MACROPHAGES. FURTHERMORE, CRIPSR STABLE KNOCKOUT OF TET1 DECREASES THE EXPRESSION OF TNFALPHA AND OTHER PRO-INFLAMMATORY CYTOKINES. IN CONCLUSION, WE SHOWED THAT TET1 CONTRIBUTES TO THE ACTIVATION OF MACROPHAGES POSSIBLY THROUGH REGULATION OF 5-HYDROXYMETHYLATION IN THE PROMOTER OF PRO-INFLAMMATORY CYTOKINE GENES. THE TET1 ENZYME COULD BE A PROMISING THERAPEUTIC TARGET TO INHIBIT THE PERSISTENT INFLAMMATION CAUSED BY MACROPHAGES IN CHRONIC INFLAMMATORY DISEASES. 2019 16 3893 28 LACTATE INDUCES METABOLIC AND EPIGENETIC REPROGRAMMING OF PRO-INFLAMMATORY TH17 CELLS. INCREASED LACTATE LEVELS IN THE TISSUE MICROENVIRONMENT ARE A WELL-KNOWN FEATURE OF CHRONIC INFLAMMATION. HOWEVER, THE ROLE OF LACTATE IN REGULATING T CELL FUNCTION REMAINS CONTROVERSIAL. HERE, WE DEMONSTRATE THAT EXTRACELLULAR LACTATE PREDOMINANTLY INDUCES DEREGULATION OF THE TH17-SPECIFIC GENE EXPRESSION PROGRAM BY MODULATING THE METABOLIC AND EPIGENETIC STATUS OF TH17 CELLS. FOLLOWING LACTATE TREATMENT, TH17 CELLS SIGNIFICANTLY REDUCED THEIR IL-17A PRODUCTION AND UPREGULATED FOXP3 EXPRESSION THROUGH ROS-DRIVEN IL-2 SECRETION. MOREOVER, WE OBSERVED INCREASED LEVELS OF GENOME-WIDE HISTONE H3K18 LACTYLATION, A RECENTLY DESCRIBED MARKER FOR ACTIVE CHROMATIN IN MACROPHAGES, IN LACTATE-TREATED TH17 CELLS. IN ADDITION, WE SHOW THAT HIGH LACTATE CONCENTRATIONS SUPPRESS TH17 PATHOGENICITY DURING INTESTINAL INFLAMMATION IN MICE. THESE RESULTS INDICATE THAT LACTATE IS CAPABLE OF REPROGRAMMING PRO-INFLAMMATORY T CELL PHENOTYPES INTO REGULATORY T CELLS. 2022 17 4040 26 MACROPHAGE PLASTICITY AND POLARIZATION: IN VIVO VERITAS. DIVERSITY AND PLASTICITY ARE HALLMARKS OF CELLS OF THE MONOCYTE-MACROPHAGE LINEAGE. IN RESPONSE TO IFNS, TOLL-LIKE RECEPTOR ENGAGEMENT, OR IL-4/IL-13 SIGNALING, MACROPHAGES UNDERGO M1 (CLASSICAL) OR M2 (ALTERNATIVE) ACTIVATION, WHICH REPRESENT EXTREMES OF A CONTINUUM IN A UNIVERSE OF ACTIVATION STATES. PROGRESS HAS NOW BEEN MADE IN DEFINING THE SIGNALING PATHWAYS, TRANSCRIPTIONAL NETWORKS, AND EPIGENETIC MECHANISMS UNDERLYING M1-M2 OR M2-LIKE POLARIZED ACTIVATION. FUNCTIONAL SKEWING OF MONONUCLEAR PHAGOCYTES OCCURS IN VIVO UNDER PHYSIOLOGICAL CONDITIONS (E.G., ONTOGENESIS AND PREGNANCY) AND IN PATHOLOGY (ALLERGIC AND CHRONIC INFLAMMATION, TISSUE REPAIR, INFECTION, AND CANCER). HOWEVER, IN SELECTED PRECLINICAL AND CLINICAL CONDITIONS, COEXISTENCE OF CELLS IN DIFFERENT ACTIVATION STATES AND UNIQUE OR MIXED PHENOTYPES HAVE BEEN OBSERVED, A REFLECTION OF DYNAMIC CHANGES AND COMPLEX TISSUE-DERIVED SIGNALS. THE IDENTIFICATION OF MECHANISMS AND MOLECULES ASSOCIATED WITH MACROPHAGE PLASTICITY AND POLARIZED ACTIVATION PROVIDES A BASIS FOR MACROPHAGE-CENTERED DIAGNOSTIC AND THERAPEUTIC STRATEGIES. 2012 18 6764 35 ZINC DEFICIENCY ENHANCED INFLAMMATORY RESPONSE BY INCREASING IMMUNE CELL ACTIVATION AND INDUCING IL6 PROMOTER DEMETHYLATION. SCOPE: ZINC DEFICIENCY RESULTS IN IMMUNE DYSFUNCTION AND PROMOTES SYSTEMIC INFLAMMATION. THE OBJECTIVE OF THIS STUDY WAS TO EXAMINE THE EFFECTS OF ZINC DEFICIENCY ON CELLULAR IMMUNE ACTIVATION AND EPIGENETIC MECHANISMS THAT PROMOTE INFLAMMATION. THIS WORK IS POTENTIALLY RELEVANT TO THE AGING POPULATION GIVEN THAT AGE-RELATED IMMUNE DEFECTS, INCLUDING CHRONIC INFLAMMATION, COINCIDE WITH DECLINING ZINC STATUS. METHODS AND RESULTS: AN IN VITRO CELL CULTURE SYSTEM AND THE AGED MOUSE MODEL WERE USED TO CHARACTERIZE IMMUNE ACTIVATION AND DNA METHYLATION PROFILES THAT MAY CONTRIBUTE TO THE ENHANCED PROINFLAMMATORY RESPONSE MEDIATED BY ZINC DEFICIENCY. ZINC DEFICIENCY UPREGULATED CELL ACTIVATION MARKERS ICAM1, MHC CLASS II, AND CD86 IN THP1 CELLS, WHICH COINCIDED WITH INCREASED IL1BETA AND IL6 RESPONSES FOLLOWING LPS STIMULATION. A DECREASED ZINC STATUS IN AGED MICE WAS SIMILARLY ASSOCIATED WITH INCREASED ICAM1 AND IL6 GENE EXPRESSION. REDUCED IL6 PROMOTER METHYLATION WAS OBSERVED IN ZINC-DEFICIENT THP1 CELLS, AS WELL AS IN AGED MICE AND HUMAN LYMPHOBLASTOID CELL LINES DERIVED FROM AGED INDIVIDUALS. CONCLUSION: ZINC DEFICIENCY INDUCED INFLAMMATORY RESPONSE IN PART BY ELICITING ABERRANT IMMUNE CELL ACTIVATION AND ALTERED PROMOTER METHYLATION. OUR RESULTS SUGGESTED POTENTIAL INTERACTIONS BETWEEN ZINC STATUS, EPIGENETICS, AND IMMUNE FUNCTION, AND HOW THEIR DYSREGULATION COULD CONTRIBUTE TO CHRONIC INFLAMMATION. 2015 19 911 24 CHRONIC EXPOSURE TO TNF REPROGRAMS CELL SIGNALING PATHWAYS IN FIBROBLAST-LIKE SYNOVIOCYTES BY ESTABLISHING LONG-TERM INFLAMMATORY MEMORY. FIBROBLAST-LIKE SYNOVIOCYTES (FLS) PLAY A CRITICAL ROLE IN THE PATHOGENESIS OF RHEUMATOID ARTHRITIS (RA). CHRONIC INFLAMMATION INDUCES TRANSCRIPTOMIC AND EPIGENETIC MODIFICATIONS THAT IMPARTS A PERSISTENT CATABOLIC PHENOTYPE TO THE FLS, DESPITE THEIR DISSOCIATION FROM THE INFLAMMATORY ENVIRONMENT. WE ANALYZED HIGH THROUGHPUT GENE EXPRESSION AND CHROMATIN ACCESSIBILITY DATA FROM HUMAN AND MOUSE FLS FROM OUR AND OTHER STUDIES AVAILABLE ON PUBLIC REPOSITORIES, WITH THE GOAL OF IDENTIFYING THE PERSISTENTLY REPROGRAMMED SIGNALING PATHWAYS DRIVEN BY CHRONIC INFLAMMATION. WE FOUND THAT THE GENE EXPRESSION CHANGES INDUCED BY SHORT-TERM TUMOR NECROSIS FACTOR-ALPHA (TNF) TREATMENT WERE LARGELY SUSTAINED IN THE FLS EXPOSED TO CHRONIC INFLAMMATION. THESE CHANGES THAT INCLUDED BOTH ACTIVATION AND REPRESSION OF GENE EXPRESSION, WERE ACCOMPANIED BY THE REMODELING OF CHROMATIN ACCESSIBILITY. THE SUSTAINED ACTIVATED GENES (SAGS) INCLUDED ESTABLISHED PRO-INFLAMMATORY SIGNALING COMPONENTS KNOWN TO ACT AT MULTIPLE LEVELS OF NF-KAPPAB, STAT AND AP-1 SIGNALING CASCADES. INTERESTINGLY, THE SUSTAINED REPRESSED GENES (SRGS) INCLUDED CRITICAL MEDIATORS AND TARGETS OF THE BMP SIGNALING PATHWAY. WE THUS IDENTIFIED SUSTAINED REPRESSION OF BMP SIGNALING AS A UNIQUE CONSTITUENT OF THE LONG-TERM INFLAMMATORY MEMORY INDUCED BY CHRONIC INFLAMMATION. WE POSTULATE THAT SIMULTANEOUS TARGETING OF THESE ACTIVATED AND REPRESSED SIGNALING PATHWAYS MAY BE NECESSARY TO COMBAT RA PERSISTENCE. 2020 20 4563 32 MYELOID DNA METHYLTRANSFERASE3B DEFICIENCY AGGRAVATES PULMONARY FIBROSIS BY ENHANCING PROFIBROTIC MACROPHAGE ACTIVATION. BACKGROUND: IDIOPATHIC PULMONARY FIBROSIS (IPF) IS A CHRONIC, PROGRESSIVE AND SEVERE DISEASE CHARACTERIZED BY EXCESSIVE MATRIX DEPOSITION IN THE LUNGS. MACROPHAGES PLAY CRUCIAL ROLES IN MAINTAINING LUNG HOMEOSTASIS BUT ARE ALSO CENTRAL IN THE PATHOGENESIS OF LUNG DISEASES LIKE PULMONARY FIBROSIS. ESPECIALLY, MACROPHAGE POLARIZATION/ACTIVATION SEEMS TO PLAY A CRUCIAL ROLE IN PATHOLOGY AND EPIGENETIC REPROGRAMING IS WELL-KNOWN TO REGULATE MACROPHAGE POLARIZATION. DNA METHYLATION ALTERATIONS IN IPF LUNGS HAVE BEEN WELL DOCUMENTED, BUT THE ROLE OF DNA METHYLATION IN SPECIFIC CELL TYPES, ESPECIALLY MACROPHAGES, IS POORLY DEFINED. METHODS: IN ORDER TO DETERMINE THE ROLE OF DNA METHYLATION IN MACROPHAGES DURING PULMONARY FIBROSIS, WE SUBJECTED MACROPHAGE SPECIFIC DNA METHYLTRANSFERASE (DNMT)3B, WHICH MEDIATES THE DE NOVO DNA METHYLATION, DEFICIENT MICE TO THE BLEOMYCIN-INDUCED PULMONARY FIBROSIS MODEL. MACROPHAGE POLARIZATION AND FIBROTIC PARAMETERS WERE EVALUATED AT 21 DAYS AFTER BLEOMYCIN ADMINISTRATION. DNMT3B KNOCKOUT AND WILD TYPE BONE MARROW-DERIVED MACROPHAGES WERE STIMULATED WITH EITHER INTERLEUKIN (IL)4 OR TRANSFORMING GROWTH FACTOR BETA 1 (TGFB1) IN VITRO, AFTER WHICH PROFIBROTIC GENE EXPRESSION AND DNA METHYLATION AT THE ARG1 PROMOTOR WERE DETERMINED. RESULTS: WE SHOW THAT DNMT3B DEFICIENCY PROMOTES ALTERNATIVE MACROPHAGE POLARIZATION INDUCED BY IL4 AND TGFB1 IN VITRO AND ALSO ENHANCES PROFIBROTIC MACROPHAGE POLARIZATION IN THE ALVEOLAR SPACE DURING PULMONARY FIBROSIS IN VIVO. MOREOVER, MYELOID SPECIFIC DELETION OF DNMT3B PROMOTED THE DEVELOPMENT OF EXPERIMENTAL PULMONARY FIBROSIS. CONCLUSIONS: IN SUMMARY, THESE DATA SUGGEST THAT MYELOID DNMT3B REPRESSES FIBROTIC MACROPHAGE POLARIZATION AND PROTECTS AGAINST BLEOMYCIN INDUCED PULMONARY FIBROSIS. 2022