1 4041 148 MACROPHAGE PLASTICITY IN DUCHENNE MUSCULAR DYSTROPHY: A NEXUS OF PATHOLOGICAL REMODELLING WITH THERAPEUTIC IMPLICATIONS. DUCHENNE MUSCULAR DYSTROPHY (DMD) IS CHARACTERIZED BY CHRONIC SKELETAL MUSCLE NECROSIS, LEADING TO MUSCLE REGENERATION FAILURE AND FIBROSIS. ALTHOUGH MACROPHAGES (MPS) ARE NORMALLY ESSENTIAL FOR MUSCLE REGENERATION, DYSREGULATED MP FUNCTION PROMOTES PATHOLOGICAL MUSCLE REMODELLING. INFILTRATING MPS CAN BE PREDOMINANTLY PRO-INFLAMMATORY (M1 BIASED), ANTI-INFLAMMATORY (M2 BIASED) OR OF A MIXED PHENOTYPE AND CAN ORIGINATE FROM THE ADULT BONE MARROW (MONOCYTE DEPENDENT) OR EMBRYONIC PRECURSORS (MONOCYTE INDEPENDENT). IN MDX MICE (GENETIC MODEL OF DMD) LACKING EITHER TOLL-LIKE RECEPTOR (TLR) 2 OR TLR4, IT IS FOUND THAT MP INFILTRATION OF DYSTROPHIC MUSCLE IS SIGNIFICANTLY REDUCED AND THAT THE MP PHENOTYPE IS SHIFTED TOWARD A MORE ANTI-INFLAMMATORY PROFILE. THIS IS ACCOMPANIED BY SIGNIFICANT IMPROVEMENTS IN MUSCLE HISTOLOGY AND FORCE PRODUCTION. LACK OF THE CHEMOKINE RECEPTOR CCR2, WHICH IMPEDES MONOCYTE RELEASE FROM THE BONE MARROW, LEADS TO SIMILAR BENEFICIAL EFFECTS IN MDX MICE. EVIDENCE WAS ALSO FOUND FOR TLR4-REGULATED INDUCTION OF TRAINED INNATE IMMUNITY IN MPS CULTURED FROM THE BONE MARROW OF MDX MICE BEFORE THEIR ENTRY INTO THE MUSCLE. THESE MPS EXHIBIT EPIGENETIC AND METABOLIC ALTERATIONS, ACCOMPANIED BY NON-SPECIFIC HYPER-RESPONSIVENESS TO MULTIPLE STIMULI, WHICH IS MANIFESTED BY POTENTIATED UPREGULATION OF BOTH PRO- AND ANTI-INFLAMMATORY GENES. IN SUMMARY, EXAGGERATED RECRUITMENT OF MONOCYTE-DERIVED MPS AND SIGNS OF TRAINED INNATE IMMUNITY AT THE LEVEL OF THE BONE MARROW ARE FEATURES OF THE IMMUNOPHENOTYPE ASSOCIATED WITH DYSTROPHIC MUSCLE DISEASE. THESE PHENOMENA ARE REGULATED BY TOLL-LIKE RECEPTORS THAT BIND ENDOGENOUS DAMAGE-ASSOCIATED MOLECULAR PATTERN (DAMP) MOLECULES, SUGGESTING THAT DAMP RELEASE FROM DYSTROPHIC MUSCLES MODULATES MP PLASTICITY AT THE BONE MARROW LEVEL THROUGH TOLL-LIKE RECEPTOR-DRIVEN MECHANISMS. 2022 2 3937 35 LKB1 SIGNALING IS ALTERED IN SKELETAL MUSCLE OF A DUCHENNE MUSCULAR DYSTROPHY MOUSE MODEL. THE POTENTIAL ROLE OF LIVER KINASE B1 (LKB1) IN THE ALTERED ACTIVATION OF THE MASTER METABOLIC AND EPIGENETIC REGULATOR ADENOSINE MONOPHOSPHATE-ACTIVATED PROTEIN KINASE (AMPK) IN DUCHENNE MUSCULAR DYSTROPHY HAS NOT BEEN INVESTIGATED SO FAR. HENCE, WE ANALYZED BOTH GENE AND PROTEIN LEVELS OF LKB1 AND ITS RELATED TARGETS IN GASTROCNEMIUS MUSCLES OF ADULT C57BL/10 MDX MICE AND D2 MDX MICE, A MODEL WITH A MORE SEVERE DYSTROPHIC PHENOTYPE, AS WELL AS THE SENSITIVITY OF THE LKB1-AMPK PATHWAY TO AMPK ACTIVATORS, SUCH AS CHRONIC EXERCISE. OUR DATA SHOW, FOR THE FIRST TIME, A REDUCTION IN THE LEVELS OF LKB1 AND ACCESSORY PROTEINS, MO25 AND STRADALPHA, IN BOTH MDX STRAINS VERSUS THE RESPECTIVE WILD TYPE, WHICH WAS FURTHER IMPAIRED BY EXERCISE, IN PARALLEL WITH A LACK OF FURTHER PHOSPHORYLATION OF AMPK. THE AMPK-LIKE KINASE SALT-INDUCIBLE KINASE (SIK) AND CLASS II HISTONE DEACETYLASES, ALONG WITH EXPRESSION OF THE HDAC TARGET GENE MEF2C, WERE ALSO ALTERED, SUPPORTING AN IMPAIRMENT OF LKB1-SIK-CLASS II HISTONE DEACETYLASE SIGNALING. OUR RESULTS DEMONSTRATE THAT LKB1 MAY BE INVOLVED IN DYSTROPHIC PROGRESSION, PAVING THE WAY FOR FUTURE PRECLINICAL STUDIES. 2023 3 5327 30 PULSED GLUCOCORTICOIDS ENHANCE DYSTROPHIC MUSCLE PERFORMANCE THROUGH EPIGENETIC-METABOLIC REPROGRAMMING. IN HUMANS, CHRONIC GLUCOCORTICOID USE IS ASSOCIATED WITH SIDE EFFECTS LIKE MUSCLE WASTING, OBESITY, AND METABOLIC SYNDROME. INTERMITTENT STEROID DOSING HAS BEEN PROPOSED IN DUCHENNE MUSCULAR DYSTROPHY PATIENTS TO MITIGATE THE SIDE EFFECTS SEEN WITH DAILY STEROID INTAKE. WE EVALUATED BIOMARKERS FROM DUCHENNE MUSCULAR DYSTROPHY PATIENTS, FINDING THAT, COMPARED WITH CHRONIC DAILY STEROID USE, WEEKEND STEROID USE WAS ASSOCIATED WITH REDUCED SERUM INSULIN, FREE FATTY ACIDS, AND BRANCHED CHAIN AMINO ACIDS, AS WELL AS REDUCTION IN FAT MASS DESPITE HAVING SIMILAR BMIS. WE REASONED THAT INTERMITTENT PREDNISONE ADMINISTRATION IN DYSTROPHIC MICE WOULD ALTER MUSCLE EPIGENOMIC SIGNATURES, AND WE IDENTIFIED THE COORDINATED ACTION OF THE GLUCOCORTICOID RECEPTOR, KLF15 AND MEF2C AS MEDIATORS OF A GENE EXPRESSION PROGRAM DRIVING METABOLIC REPROGRAMMING AND ENHANCED NUTRIENT UTILIZATION. MUSCLE LACKING KLF15 FAILED TO RESPOND TO INTERMITTENT STEROIDS. FURTHERMORE, COADMINISTRATION OF THE HISTONE ACETYLTRANSFERASE INHIBITOR ANACARDIC ACID WITH STEROIDS IN MDX MICE ELIMINATED STEROID-SPECIFIC EPIGENETIC MARKS AND ABROGATED THE STEROID RESPONSE. TOGETHER, THESE FINDINGS INDICATE THAT INTERMITTENT, REPEATED EXPOSURE TO GLUCOCORTICOIDS PROMOTES PERFORMANCE IN DYSTROPHIC MUSCLE THROUGH AN EPIGENETIC PROGRAM THAT ENHANCES NUTRIENT UTILIZATION. 2019 4 6495 53 TRAINED IMMUNITY AS A POTENTIAL TARGET FOR THERAPEUTIC IMMUNOMODULATION IN DUCHENNE MUSCULAR DYSTROPHY. DYSREGULATED INFLAMMATION INVOLVING INNATE IMMUNE CELLS, PARTICULARLY OF THE MONOCYTE/MACROPHAGE LINEAGE, IS A KEY CONTRIBUTOR TO THE PATHOGENESIS OF DUCHENNE MUSCULAR DYSTROPHY (DMD). TRAINED IMMUNITY IS AN EVOLUTIONARILY ANCIENT PROTECTIVE MECHANISM AGAINST INFECTION, IN WHICH EPIGENETIC AND METABOLIC ALTERATIONS CONFER NON-SPECIFIC HYPERRESPONSIVENESS OF INNATE IMMUNE CELLS TO VARIOUS STIMULI. RECENT WORK IN AN ANIMAL MODEL OF DMD (MDX MICE) HAS SHOWN THAT MACROPHAGES EXHIBIT CARDINAL FEATURES OF TRAINED IMMUNITY, INCLUDING THE PRESENCE OF INNATE IMMUNE SYSTEM "MEMORY". THE LATTER IS REFLECTED BY EPIGENETIC CHANGES AND DURABLE TRANSMISSIBILITY OF THE TRAINED PHENOTYPE TO HEALTHY NON-DYSTROPHIC MICE BY BONE MARROW TRANSPLANTATION. MECHANISTICALLY, IT IS SUGGESTED THAT A TOLL-LIKE RECEPTOR (TLR) 4-REGULATED, MEMORY-LIKE CAPACITY OF INNATE IMMUNITY IS INDUCED AT THE LEVEL OF THE BONE MARROW BY FACTORS RELEASED FROM THE DAMAGED MUSCLES, LEADING TO EXAGGERATED UPREGULATION OF BOTH PRO- AND ANTI-INFLAMMATORY GENES. HERE WE PROPOSE A CONCEPTUAL FRAMEWORK FOR THE INVOLVEMENT OF TRAINED IMMUNITY IN DMD PATHOGENESIS AND ITS POTENTIAL TO SERVE AS A NEW THERAPEUTIC TARGET. 2023 5 2476 35 EPIGENETIC UPREGULATION OF CCL2 AND CCL3 VIA HISTONE MODIFICATIONS IN INFILTRATING MACROPHAGES AFTER PERIPHERAL NERVE INJURY. TO GAIN INSIGHT INTO THE EPIGENETIC REGULATION OF CC-CHEMOKINE LIGAND (CCL) 2 AND CCL3, KEY PLAYERS IN THE PERIPHERAL SENSITIZATION LEADING TO NEUROPATHIC PAIN, WE EXAMINED THE RELATIONSHIP BETWEEN HISTONE H3 MODIFICATION AND THE UPREGULATION OF THESE MOLECULES USING A MOUSE MODEL OF NEUROPATHIC PAIN AFTER PARTIAL SCIATIC NERVE LIGATION (PSL). WE FOUND THAT CIRCUITING BONE MARROW (BM)-DERIVED MACROPHAGES INFILTRATED INTO THE INJURED SCIATIC NERVE (SCN) USING ENHANCED GREEN FLUORESCENT PROTEIN CHIMERIC MICE. THE MRNA LEVELS OF CCL2, CCL3 AND THEIR RECEPTORS (CCR2 AND CCR1/CCR5, RESPECTIVELY) WERE INCREASED IN THE INJURED SCN. CHROMATIN IMMUNOPRECIPITATION ASSAY REVEALED THAT LEVELS OF LYSINE 9-ACETYLATED HISTONE H3 (H3K9AC) AND LYSINE 4-TRIMETHYLATED H3 (H3K4ME(3)) IN THE PROMOTER REGIONS OF THE CCL2 AND CCL3 GENES WERE INCREASED IN THE INJURED SCN AFTER PSL, INDICATING THE ENHANCEMENT OF GENE EXPRESSION. IMMUNOREACTIVITY FOR H3K9AC AND H3K4ME(3) WAS LOCALIZED IN THE NUCLEI OF INFILTRATING BM-DERIVED CELLS AND CCL-EXPRESSING CELLS IN THE INJURED SCN. WE OBSERVED H3K9AC AND H3K4ME(3) MAINLY IN THE NUCLEI OF RECRUITED MACROPHAGES ON DAY 7 AFTER PSL. FURTHERMORE, UPREGULATION OF CCLS AND CCRS WERE SUPPRESSED BY HISTONE ACETYLTRANSFERASE INHIBITOR, ANACARDIC ACID. TAKEN TOGETHER, OUR FINDINGS DEMONSTRATE THAT CCL2 AND CCL3 ARE UPREGULATED IN THE INJURED PERIPHERAL NERVE THROUGH EPIGENETIC HISTONE MODIFICATION IN INFILTRATING IMMUNE CELLS SUCH AS MACROPHAGES. THESE CHEMOKINE CASCADES MAY SUBSEQUENTLY ELICIT CHRONIC NEUROINFLAMMATION FOLLOWING NERVE INJURY. 2013 6 545 21 ATTENUATED EPIGENETIC SUPPRESSION OF MUSCLE STEM CELL NECROPTOSIS IS REQUIRED FOR EFFICIENT REGENERATION OF DYSTROPHIC MUSCLES. SOMATIC STEM CELLS EXPAND MASSIVELY DURING TISSUE REGENERATION, WHICH MIGHT REQUIRE CONTROL OF CELL FITNESS, ALLOWING ELIMINATION OF NON-COMPETITIVE, POTENTIALLY HARMFUL CELLS. HOW OR IF SUCH CELLS ARE REMOVED TO RESTORE ORGAN FUNCTION IS NOT FULLY UNDERSTOOD. HERE, WE SHOW THAT A SUBSTANTIAL FRACTION OF MUSCLE STEM CELLS (MUSCS) UNDERGO NECROPTOSIS BECAUSE OF EPIGENETIC REWIRING DURING CHRONIC SKELETAL MUSCLE REGENERATION, WHICH IS REQUIRED FOR EFFICIENT REGENERATION OF DYSTROPHIC MUSCLES. INHIBITION OF NECROPTOSIS STRONGLY ENHANCES SUPPRESSION OF MUSC EXPANSION IN A NON-CELL-AUTONOMOUS MANNER. PREVENTION OF NECROPTOSIS IN MUSCS OF HEALTHY MUSCLES IS MEDIATED BY THE CHROMATIN REMODELER CHD4, WHICH DIRECTLY REPRESSES THE NECROPTOTIC EFFECTOR RIPK3, WHILE CHD4-DEPENDENT RIPK3 REPRESSION IS DRAMATICALLY ATTENUATED IN DYSTROPHIC MUSCLES. LOSS OF RIPK3 REPRESSION BY INACTIVATION OF CHD4 CAUSES MASSIVE NECROPTOSIS OF MUSCS, ABOLISHING REGENERATION. OUR STUDY DEMONSTRATES HOW PROGRAMMED CELL DEATH IN MUSCS IS TIGHTLY CONTROLLED TO ACHIEVE OPTIMAL TISSUE REGENERATION. 2020 7 2241 43 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 8 6376 32 THE ROLE OF NEUTROPHILS IN TRAINED IMMUNITY. THE PRINCIPLE OF TRAINED IMMUNITY REPRESENTS INNATE IMMUNE MEMORY DUE TO SUSTAINED, MAINLY EPIGENETIC, CHANGES TRIGGERED BY ENDOGENOUS OR EXOGENOUS STIMULI IN BONE MARROW (BM) PROGENITORS (CENTRAL TRAINED IMMUNITY) AND THEIR INNATE IMMUNE CELL PROGENY, THEREBY TRIGGERING ELEVATED RESPONSIVENESS AGAINST SECONDARY STIMULI. BM PROGENITORS CAN RESPOND TO MICROBIAL AND STERILE SIGNALS, THEREBY POSSIBLY ACQUIRING TRAINED IMMUNITY-MEDIATED LONG-LASTING ALTERATIONS THAT MAY SHAPE THE FATE AND FUNCTION OF THEIR PROGENY, FOR EXAMPLE, NEUTROPHILS. NEUTROPHILS, THE MOST ABUNDANT INNATE IMMUNE CELL POPULATION, ARE PRODUCED IN THE BM FROM COMMITTED PROGENITOR CELLS IN A PROCESS DESIGNATED GRANULOPOIESIS. NEUTROPHILS ARE THE FIRST RESPONDERS AGAINST INFECTIOUS OR INFLAMMATORY CHALLENGES AND HAVE VERSATILE FUNCTIONS IN IMMUNITY. TOGETHER WITH OTHER INNATE IMMUNE CELLS, NEUTROPHILS ARE EFFECTORS OF PERIPHERAL TRAINED IMMUNITY. HOWEVER, GIVEN THE SHORT LIFETIME OF NEUTROPHILS, THEIR ABILITY TO ACQUIRE IMMUNOLOGICAL MEMORY MAY LIE IN THE CENTRAL TRAINING OF THEIR BM PROGENITORS RESULTING IN GENERATION OF REPROGRAMMED, THAT IS, "TRAINED", NEUTROPHILS. ALTHOUGH TRAINED IMMUNITY MAY HAVE BENEFICIAL EFFECTS IN INFECTION OR CANCER, IT MAY ALSO MEDIATE DETRIMENTAL OUTCOMES IN CHRONIC INFLAMMATION. HERE, WE REVIEW THE EMERGING RESEARCH AREA OF TRAINED IMMUNITY WITH A PARTICULAR EMPHASIS ON THE ROLE OF NEUTROPHILS AND GRANULOPOIESIS. 2023 9 2067 41 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 10 3878 38 KDM6B OVEREXPRESSION ACTIVATES INNATE IMMUNE SIGNALING AND IMPAIRS HEMATOPOIESIS IN MICE. KDM6B IS AN EPIGENETIC REGULATOR THAT MEDIATES TRANSCRIPTIONAL ACTIVATION DURING DIFFERENTIATION, INCLUDING IN BONE MARROW (BM) HEMATOPOIETIC STEM AND PROGENITOR CELLS (HSPCS). OVEREXPRESSION OF KDM6B HAS BEEN REPORTED IN BM HSPCS OF PATIENTS WITH MYELODYSPLASTIC SYNDROMES (MDS) AND CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML). WHETHER THE OVEREXPRESSION OF KDM6B CONTRIBUTES TO THE PATHOGENESIS OF THESE DISEASES REMAINS TO BE ELUCIDATED. TO STUDY THIS, WE GENERATED A VAV-KDM6B MOUSE MODEL, WHICH OVEREXPRESSES KDM6B IN THE HEMATOPOIETIC COMPARTMENT. KDM6B OVEREXPRESSION ALONE LED TO MILD HEMATOPOIETIC PHENOTYPE, AND CHRONIC INNATE IMMUNE STIMULATION OF VAV-KDM6B MICE WITH THE TOLL-LIKE RECEPTOR (TLR) LIGAND LIPOPOLYSACCHARIDE (LPS) RESULTED IN SIGNIFICANT HEMATOPOIETIC DEFECTS. THESE DEFECTS RECAPITULATED FEATURES OF MDS AND CMML, INCLUDING LEUKOPENIA, DYSPLASIA, AND COMPROMISED REPOPULATING FUNCTION OF BM HSPCS. TRANSCRIPTOME STUDIES INDICATED THAT KDM6B OVEREXPRESSION ALONE COULD LEAD TO ACTIVATION OF DISEASE-RELEVANT GENES SUCH AS S100A9 IN BM HSPCS, AND WHEN COMBINED WITH INNATE IMMUNE STIMULATION, KDM6B OVEREXPRESSION RESULTED IN MORE PROFOUND OVEREXPRESSION OF INNATE IMMUNE AND DISEASE-RELEVANT GENES, INDICATING THAT KDM6B WAS INVOLVED IN THE ACTIVATION OF INNATE IMMUNE SIGNALING IN BM HSPCS. FINALLY, PHARMACOLOGIC INHIBITION OF KDM6B WITH THE SMALL MOLECULE INHIBITOR GSK-J4 AMELIORATED THE INEFFECTIVE HEMATOPOIESIS OBSERVED IN VAV-KDM6B MICE. THIS EFFECT WAS ALSO OBSERVED WHEN GSK-J4 WAS APPLIED TO THE PRIMARY BM HSPCS OF PATIENTS WITH MDS BY IMPROVING THEIR REPOPULATING FUNCTION. THESE RESULTS INDICATE THAT OVEREXPRESSION OF KDM6B MEDIATES ACTIVATION OF INNATE IMMUNE SIGNALS AND HAS A ROLE IN MDS AND CMML PATHOGENESIS, AND THAT KDM6B TARGETING HAS THERAPEUTIC POTENTIAL IN THESE MYELOID DISORDERS. 2018 11 6578 40 TREATMENT WITH TRICHURIS SUIS SOLUBLE PRODUCTS DURING MONOCYTE-TO-MACROPHAGE DIFFERENTIATION REDUCES INFLAMMATORY RESPONSES THROUGH EPIGENETIC REMODELING. HELMINTHS HAVE STRONG IMMUNOREGULATORY PROPERTIES THAT MAY BE EXPLOITED IN TREATMENT OF CHRONIC IMMUNE DISORDERS, SUCH AS MULTIPLE SCLEROSIS AND INFLAMMATORY BOWEL DISEASE. ESSENTIAL PLAYERS IN THE PATHOGENESIS OF THESE DISEASES ARE PROINFLAMMATORY MACROPHAGES. WE PRESENT EVIDENCE THAT HELMINTHS MODULATE THE FUNCTION AND PHENOTYPE OF THESE INNATE IMMUNE CELLS. WE FOUND THAT SOLUBLE PRODUCTS DERIVED FROM THE TRICHURIS SUIS (TSSP) SIGNIFICANTLY AFFECT THE DIFFERENTIATION OF MONOCYTES INTO MACROPHAGES AND THEIR SUBSEQUENT POLARIZATION. TSSPS REDUCE THE EXPRESSION AND PRODUCTION OF INFLAMMATORY CYTOKINES, INCLUDING IL-6 AND TNF, IN HUMAN PROINFLAMMATORY M1 MACROPHAGES. TSSPS INDUCE A CONCOMITANT ANTI-INFLAMMATORY M2 SIGNATURE, WITH INCREASED IL-10 PRODUCTION. FURTHERMORE, THEY SUPPRESS CHIT ACTIVITY AND ENHANCE SECRETION OF MATRIX METALLOPROTEINASE 9. SHORT-TERM TRIGGERING OF MONOCYTES WITH TSSPS EARLY DURING MONOCYTE-TO-MACROPHAGE DIFFERENTIATION IMPRINTED THESE PHENOTYPIC ALTERATIONS, SUGGESTING LONG-LASTING EPIGENETIC CHANGES. THE TSSP-INDUCED EFFECTS IN M1 MACROPHAGES WERE COMPLETELY REVERSED BY INHIBITING HISTONE DEACETYLASES, WHICH CORRESPONDED WITH DECREASED HISTONE ACETYLATION AT THE TNF AND IL6 PROMOTERS. THESE RESULTS DEMONSTRATE THAT TSSPS HAVE A POTENT AND SUSTAINED IMMUNOMODULATORY EFFECT ON HUMAN MACROPHAGE DIFFERENTIATION AND POLARIZATION THROUGH EPIGENETIC REMODELING AND PROVIDE NEW INSIGHTS INTO THE MECHANISMS BY WHICH HELMINTHS MODULATE HUMAN IMMUNE RESPONSES.-HOEKSEMA, M. A., LAAN, L. C., POSTMA, J. J., CUMMINGS, R. D., DE WINTHER, M. P. J., DIJKSTRA, C. D., VAN DIE, I., KOOIJ, G. TREATMENT WITH TRICHURIS SUIS SOLUBLE PRODUCTS DURING MONOCYTE-TO-MACROPHAGE DIFFERENTIATION REDUCES INFLAMMATORY RESPONSES THROUGH EPIGENETIC REMODELING. 2016 12 3339 37 HISTONE DEACETYLASE ISOFORMS DIFFERENTIALLY MODULATE INFLAMMATORY AND AUTOANTIBODY RESPONSES IN A MOUSE MODEL OF MYASTHENIA GRAVIS. MYASTHENIA GRAVIS (MG) IS AN AUTOIMMUNE DISEASE CHARACTERIZED BY CHRONIC MUSCLE FATIGUE AND WEAKNESS CAUSED BY AUTOANTIBODIES AND COMPLEMENT-MEDIATED DAMAGE AT NEUROMUSCULAR JUNCTIONS. HISTONE DEACETYLASES (HDACS) ARE CRUCIAL EPIGENETIC REGULATORS OF PROINFLAMMATORY GENE EXPRESSION; HOWEVER, IT IS UNCLEAR WHETHER HDACS MODULATE CHRONIC INFLAMMATION OR AUTOANTIBODY PRODUCTION ASSOCIATED WITH MG PATHOGENESIS. WE EXAMINED EXPRESSION PROFILES AND SERUM LEVELS OF KEY INFLAMMATORY CYTOKINES (IL-6 AND IL-21) AND ACETYLCHOLINE RECEPTOR (ACHR)-SPECIFIC AUTOANTIBODIES FOLLOWING PHARMACOLOGICAL INHIBITION OF KEY HDAC ISOFORMS IN A MOUSE MODEL OF MG. WE FOUND THAT HDAC INHIBITION SIGNIFICANTLY REDUCED THE PRODUCTION OF IL-6, BUT NOT IL-21, IN ACHR-STIMULATED PBMCS AND SPLENOCYTES (N = 5 PER GROUP). TRICHOSTATIN (PAN-HDAC INHIBITOR) TREATMENT OF MG-PBMCS (N = 2) ALSO EXHIBITED REDUCED PRODUCTION OF INDUCED IL-6. ALTHOUGH HDAC1 INHIBITION LOWERED IL-6 LEVELS THE MOST, HDAC2 INHIBITION DEPLETED INTRACELLULAR IL-6 AND MARKEDLY REDUCED SERUM ANTI-ACHR IGG2B IN EAMG MICE. THE TRANSCRIPTOMIC PROFILING AND PATHWAY MAPPING ALSO REVEALED THAT AUTOIMMUNITY-LINKED, MAJOR CELL SIGNALING PATHWAYS WERE DIFFERENTIALLY ALTERED BY HDAC1/2 INHIBITION. HDAC INHIBITION-MEDIATED REDUCTION IN IL-6 AND AUTOANTIBODY LEVELS ALSO CORRELATED WITH MILDER DISEASE AND PRESERVATION OF MUSCLE ACHR IN THE TREATED MICE. OVERALL, OUR FINDINGS REVEALED ISOFORM-SPECIFIC FUNCTIONAL VARIANCE OF HDACS IN REDUCING INFLAMMATION AND IDENTIFIED HDAC-REGULATED MANY GENES UNDERLYING SPECIFIC INFLAMMATORY AND AUTOANTIBODY PATHWAYS IN EAMG. THUS, THE STUDY PROVIDES A RATIONALE FOR FURTHER RESEARCH TO EVALUATE THE HDACS OR THEIR GENE TARGETS AS A POTENTIAL ADJUNCT TREATMENT FOR MG. 2021 13 4042 38 MACROPHAGES ACQUIRE A TNF-DEPENDENT INFLAMMATORY MEMORY IN ALLERGIC ASTHMA. BACKGROUND: INFECTIOUS AGENTS CAN REPROGRAM OR "TRAIN" MACROPHAGES AND THEIR PROGENITORS TO RESPOND MORE READILY TO SUBSEQUENT INSULTS. HOWEVER, WHETHER SUCH AN INFLAMMATORY MEMORY EXISTS IN TYPE 2 INFLAMMATORY CONDITIONS SUCH AS ALLERGIC ASTHMA WAS NOT KNOWN. OBJECTIVE: WE SOUGHT TO DECIPHER MACROPHAGE-TRAINED IMMUNITY IN ALLERGIC ASTHMA. METHODS: WE USED A COMBINATION OF CLINICAL SAMPLING OF HOUSE DUST MITE (HDM)-ALLERGIC PATIENTS, HDM-INDUCED ALLERGIC AIRWAY INFLAMMATION IN MICE, AND AN IN VITRO TRAINING SETUP TO ANALYZE PERSISTENT CHANGES IN MACROPHAGE EICOSANOID, CYTOKINE, AND CHEMOKINE PRODUCTION AS WELL AS THE UNDERLYING METABOLIC AND EPIGENETIC MECHANISMS. TRANSCRIPTIONAL AND METABOLIC PROFILES OF PATIENT-DERIVED AND IN VITRO TRAINED MACROPHAGES WERE ASSESSED BY RNA SEQUENCING OR METABOLIC FLUX ANALYSIS AND LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY ANALYSIS, RESPECTIVELY. RESULTS: WE FOUND THAT MACROPHAGES DIFFERENTIATED FROM BONE MARROW OR BLOOD MONOCYTE PROGENITORS OF HDM-ALLERGIC MICE OR ASTHMA PATIENTS SHOW INFLAMMATORY TRANSCRIPTIONAL REPROGRAMMING AND EXCESSIVE MEDIATOR (TNF-ALPHA, CCL17, LEUKOTRIENE, PGE(2), IL-6) RESPONSES UPON STIMULATION. MACROPHAGES FROM HDM-ALLERGIC MICE INITIALLY EXHIBITED A TYPE 2 IMPRINT, WHICH SHIFTED TOWARD A CLASSICAL INFLAMMATORY TRAINING OVER TIME. HDM-INDUCED ALLERGIC AIRWAY INFLAMMATION ELICITED A METABOLICALLY ACTIVATED MACROPHAGE PHENOTYPE, PRODUCING HIGH AMOUNTS OF 2-HYDROXYGLUTARATE (2-HG). HDM-INDUCED MACROPHAGE TRAINING IN VITRO WAS MEDIATED BY A FORMYL PEPTIDE RECEPTOR 2-TNF-2-HG-PGE(2)/PGE(2) RECEPTOR 2 AXIS, RESULTING IN AN M2-LIKE MACROPHAGE PHENOTYPE WITH HIGH CCL17 PRODUCTION. TNF BLOCKADE BY ETANERCEPT OR GENETIC ABLATION OF TNF IN MYELOID CELLS PREVENTED THE INFLAMMATORY IMPRINTING OF BONE MARROW-DERIVED MACROPHAGES FROM HDM-ALLERGIC MICE. CONCLUSION: ALLERGEN-TRIGGERED INFLAMMATION DRIVES A TNF-DEPENDENT INNATE MEMORY, WHICH MAY PERPETUATE AND EXACERBATE CHRONIC TYPE 2 AIRWAY INFLAMMATION AND THUS REPRESENTS A TARGET FOR ASTHMA THERAPY. 2022 14 547 23 ATTENUATED TLR4/MAPK SIGNALING IN MONOCYTES FROM PATIENTS WITH CRMO RESULTS IN IMPAIRED IL-10 EXPRESSION. CHRONIC RECURRENT MULTIFOCAL OSTEOMYELITIS (CRMO) IS AN AUTOINFLAMMATORY BONE DISORDER OF UNKNOWN ORIGIN. WE PREVIOUSLY DEMONSTRATED THAT MONOCYTES FROM CRMO PATIENTS FAIL TO EXPRESS THE IMMUNE-MODULATORY CYTOKINE INTERLEUKIN-10 (IL-10) IN A CHROMATIN DEPENDENT MANNER. HERE, WE DEMONSTRATE THAT ATTENUATED EXTRACELLULAR-SIGNAL REGULATED KINASE (ERK)1 AND 2 SIGNALING IN RESPONSE TO TLR4 ACTIVATION RESULTS IN FAILURE TO INDUCE IL-10 EXPRESSION IN MONOCYTES FROM CRMO PATIENTS. ATTENUATED ERK1/2 ACTIVATION RESULTS IN 1) REDUCED LEVELS OF SP-1, A TRANSCRIPTION FACTOR THAT INDUCES IL-10 EXPRESSION IN MONOCYTES, AND 2) IMPAIRED H3S10 PHOSPHORYLATION OF THE IL10 PROMOTER, AN ACTIVATING EPIGENETIC MARK. THE PRO-INFLAMMATORY CYTOKINES TUMOR NECROSIS FACTOR (TNF)ALPHA AND IL-6 ARE NOT NEGATIVELY AFFECTED, RESULTING IN AN IMBALANCE TOWARDS PRO-INFLAMMATORY CYTOKINES. THUS, IMPAIRED ERK1/2 SIGNALING WITH SUBSEQUENTLY REDUCED SP-1 EXPRESSION AND H3S10 PHOSPHORYLATION OF THE IL10 PROMOTER MAY CENTRALLY CONTRIBUTE TO THE PATHOPHYSIOLOGY OF CRMO. 2012 15 2247 29 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 16 2311 26 EPIGENETIC REGULATION OF CYTOSOLIC PHOSPHOLIPASE A2 IN SH-SY5Y HUMAN NEUROBLASTOMA CELLS. GROUP IVA CYTOSOLIC PHOSPHOLIPASE A2 (CPLA2 OR PLA2G4A) IS A KEY ENZYME THAT CONTRIBUTES TO INFLAMMATION VIA THE GENERATION OF ARACHIDONIC ACID AND EICOSANOIDS. WHILE MUCH IS KNOWN ABOUT REGULATION OF CPLA2 BY POSTTRANSLATIONAL MODIFICATION SUCH AS PHOSPHORYLATION, LITTLE IS KNOWN ABOUT ITS EPIGENETIC REGULATION. IN THIS STUDY, TREATMENT WITH HISTONE DEACETYLASE (HDAC) INHIBITORS, TRICHOSTATIN A (TSA), VALPROIC ACID, TUBACIN AND THE CLASS I HDAC INHIBITOR, MS-275, WERE FOUND TO INCREASE CPLA2ALPHA MESSENGER RNA (MRNA) EXPRESSION IN SH-SY5Y HUMAN NEUROBLASTOMA CELLS. CO-TREATMENT OF THE HISTONE ACETYLTRANSFERASE (HAT) INHIBITOR, ANACARDIC ACID, MODULATED UPREGULATION OF CPLA2ALPHA INDUCED BY TSA. SPECIFIC INVOLVEMENT OF CLASS I HDACS AND HAT IN CPLA2ALPHA REGULATION WAS FURTHER SHOWN, AND A TIP60-SPECIFIC HAT INHIBITOR, NU9056, MODULATED THE UPREGULATION OF CPLA2ALPHA INDUCED BY MS-275. IN ADDITION, CO-TREATMENT OF WITH HISTONE METHYLTRANSFERASE (HMT) INHIBITOR, 5'-DEOXY-5'-METHYLTHIOADENOSINE (MTA) SUPPRESSED TSA-INDUCED CPLA2ALPHA UPREGULATION. THE ABOVE CHANGES IN CPLA2 MRNA EXPRESSION WERE REFLECTED AT THE PROTEIN LEVEL BY WESTERN BLOTS AND IMMUNOCYTOCHEMISTRY. CHROMATIN IMMUNOPRECIPITATION (CHIP) SHOWED TSA INCREASED BINDING OF TRIMETHYLATED H3K4 TO THE PROXIMAL PROMOTER REGION OF THE CPLA2ALPHA GENE. CELL INJURY AFTER TSA TREATMENT AS INDICATED BY LACTATE DEHYDROGENASE (LDH) RELEASE WAS MODULATED BY ANACARDIC ACID, AND A ROLE OF CPLA2 IN MEDIATING TSA-INDUCED INJURY SHOWN, AFTER CO-INCUBATION WITH THE CPLA2 SELECTIVE INHIBITOR, ARACHIDONOYL TRIFLUOROMETHYL KETONE (AACOCF3). TOGETHER, RESULTS INDICATE EPIGENETIC REGULATION OF CPLA2 AND THE POTENTIAL OF SUCH REGULATION FOR TREATMENT OF CHRONIC INFLAMMATION. 2016 17 2006 28 EPIGENETIC AUGMENTATION OF THE MACROPHAGE INFLAMMATORY PROTEIN 2/C-X-C CHEMOKINE RECEPTOR TYPE 2 AXIS THROUGH HISTONE H3 ACETYLATION IN INJURED PERIPHERAL NERVES ELICITS NEUROPATHIC PAIN. ALTHOUGH THERE IS GROWING EVIDENCE SHOWING THAT THE INVOLVEMENT OF CHEMOKINES IN THE PATHOGENESIS OF NEUROPATHIC PAIN IS ASSOCIATED WITH NEUROINFLAMMATION, THE DETAILS ARE UNCLEAR. WE INVESTIGATED THE C-X-C CHEMOKINE LIGAND TYPE 2 [MACROPHAGE INFLAMMATORY PROTEIN 2 (MIP-2)]/C-X-C CHEMOKINE RECEPTOR TYPE 2 (CXCR2) AXIS AND EPIGENETIC REGULATION OF THESE MOLECULES IN NEUROPATHIC PAIN AFTER PERIPHERAL NERVE INJURY. EXPRESSION OF MIP-2 AND CXCR2 WERE UP-REGULATED AND LOCALIZED ON ACCUMULATED NEUTROPHILS AND MACROPHAGES IN THE INJURED SCIATIC NERVE (SCN) AFTER PARTIAL SCIATIC NERVE LIGATION (PSL). PERINEURAL INJECTION OF MIP-2-NEUTRALIZING ANTIBODY (ANTI-MIP-2) OR THE CXCR2 ANTAGONIST N-(2-BROMOPHENYL)-N'-(2-HYDROXY-4-NITROPHENYL)UREA (SB225002) PREVENTED PSL-INDUCED TACTILE ALLODYNIA AND THERMAL HYPERALGESIA. PERINEURAL INJECTION OF RECOMBINANT MIP-2 ELICITED NEUROPATHIC PAIN-LIKE BEHAVIORS. ANTI-MIP-2 SUPPRESSED NEUTROPHIL ACCUMULATION IN THE SCN AFTER PSL. NEUTROPHIL DEPLETION BY INTRAPERITONEAL INJECTION OF LY6G ANTIBODY ATTENUATED PSL-INDUCED NEUROPATHIC PAIN. BOTH ANTI-MIP-2 AND SB225002 SUPPRESSED UP-REGULATION OF INFLAMMATORY CYTOKINES AND CHEMOKINES IN THE INJURED SCN. IN ADDITION, ACETYLATION OF HISTONE H3 [LYSINE (LYS9)-ACETYLATED HISTONE H3 (ACK9-H3)] ON THE PROMOTER REGION OF MIP-2 AND CXCR2 WAS INCREASED IN THE INJURED SCN AFTER PSL. EXPRESSION OF ACK9-H3 WAS OBSERVED IN THE NUCLEI OF NEUTROPHILS AND MACROPHAGES SURROUNDING THE EPINEURIUM. ADMINISTRATION OF THE HISTONE ACETYLTRANSFERASE INHIBITOR ANACARDIC ACID SUPPRESSED THE UP-REGULATION OF MIP-2 AND CXCR2 IN THE SCN AFTER PSL AND RESULTED IN THE PREVENTION OF PSL-INDUCED NEUROPATHIC PAIN. TAKEN TOGETHER, THESE RESULTS SHOW THAT AUGMENTATION OF THE MIP-2/CXCR2 AXIS BY HYPERACETYLATION OF HISTONE H3 ON THE PROMOTER REGION OF MIP-2 AND CXCR2 LOCATED IN THE INJURED PERIPHERAL NERVE ELICITS CHRONIC NEUROINFLAMMATION THROUGH NEUTROPHIL ACCUMULATION, LEADING TO NEUROPATHIC PAIN. 2012 18 5679 31 SHORT- AND LONG-TERM HINDLIMB IMMOBILIZATION AND RELOADING: PROFILE OF EPIGENETIC EVENTS IN GASTROCNEMIUS. SKELETAL MUSCLE DYSFUNCTION AND ATROPHY ARE CHARACTERISTIC FEATURES ACCOMPANYING CHRONIC CONDITIONS. EPIGENETIC EVENTS REGULATE MUSCLE MASS AND FUNCTION MAINTENANCE. WE HYPOTHESIZED THAT THE PATTERN OF EPIGENETIC EVENTS (MUSCLE-ENRICHED MICRORNAS AND HISTONE ACETYLATION) AND ACETYLATION OF TRANSCRIPTION FACTORS KNOWN TO SIGNAL MUSCLE WASTING MAY DIFFER BETWEEN EARLY- AND LATE-TIME POINTS IN SKELETAL MUSCLES OF MICE EXPOSED TO HINDLIMB IMMOBILIZATION (I) AND RECOVERY FOLLOWING I. BODY AND MUSCLE WEIGHTS, GRIP STRENGTH, MUSCLE-ENRICHED MICRORNAS, HISTONE DEACETYLASES (HDACS), ACETYLATION OF PROTEINS, HISTONES, AND TRANSCRIPTION FACTORS (TF), MYOGENIC TF FACTORS, AND MUSCLE PHENOTYPE WERE ASSESSED IN GASTROCNEMIUS OF MICE EXPOSED TO PERIODS (1, 2, 3, 7, 15, AND 30 DAYS, I GROUPS) OF HINDLIMB IMMOBILIZATION, AND IN THOSE EXPOSED TO RELOADING FOR DIFFERENT PERIODS OF TIME (1, 3, 7, 15, AND 30 DAYS, R GROUPS) FOLLOWING 7-DAY IMMOBILIZATION. COMPARED TO NON-IMMOBILIZED CONTROLS, MUSCLE WEIGHT, LIMB STRENGTH, MICRORNAS, ESPECIALLY MIR-486, SIRT1 LEVELS, AND SLOW- AND FAST-TWITCH CROSS-SECTIONAL AREAS WERE DECREASED IN MICE OF I GROUPS, WHEREAS PAX7 AND ACETYLATED FOXO1 AND FOXO3 LEVELS WERE INCREASED. MUSCLE RELOADING FOLLOWING SPLINT REMOVAL IMPROVED MUSCLE MASS LOSS, STRENGTH, AND FIBER ATROPHY, BY INCREASING MICRORNAS, PARTICULARLY MIR-486, AND SIRT1 CONTENT, WHILE DECREASING ACETYLATED FOXO1 AND FOXO3 LEVELS. IN THIS MOUSE MODEL OF DISUSE MUSCLE ATROPHY, MUSCLE-ENRICHED MICRORNAS, ESPECIALLY MIR-486, THROUGH PAX7 REGULATION DELAYED MUSCLE CELL DIFFERENTIATION FOLLOWING UNLOADING OF GASTROCNEMIUS MUSCLE. ACETYLATION OF FOXO1 AND 3 SEEMED TO DRIVE MUSCLE MASS LOSS AND ATROPHY, WHILE DEACETYLATION OF THESE FACTORS THROUGH SIRT1 WOULD ENABLE THE MUSCLE FIBERS TO REGENERATE. J. CELL. PHYSIOL. 232: 1415-1427, 2017. (C) 2016 WILEY PERIODICALS, INC. 2017 19 1862 33 EMERGENCE OF FIBROBLASTS WITH A PROINFLAMMATORY EPIGENETICALLY ALTERED PHENOTYPE IN SEVERE HYPOXIC PULMONARY HYPERTENSION. PERSISTENT ACCUMULATION OF MONOCYTES/MACROPHAGES IN THE PULMONARY ARTERY ADVENTITIAL/PERIVASCULAR AREAS OF ANIMALS AND HUMANS WITH PULMONARY HYPERTENSION HAS BEEN DOCUMENTED. THE CELLULAR MECHANISMS CONTRIBUTING TO CHRONIC INFLAMMATORY RESPONSES REMAIN UNCLEAR. WE HYPOTHESIZED THAT PERIVASCULAR INFLAMMATION IS PERPETUATED BY ACTIVATED ADVENTITIAL FIBROBLASTS, WHICH, THROUGH SUSTAINED PRODUCTION OF PROINFLAMMATORY CYTOKINES/CHEMOKINES AND ADHESION MOLECULES, INDUCE ACCUMULATION, RETENTION, AND ACTIVATION OF MONOCYTES/MACROPHAGES. WE FURTHER HYPOTHESIZED THAT THIS PROINFLAMMATORY PHENOTYPE IS THE RESULT OF THE ABNORMAL ACTIVITY OF HISTONE-MODIFYING ENZYMES, SPECIFICALLY, CLASS I HISTONE DEACETYLASES (HDACS). PULMONARY ADVENTITIAL FIBROBLASTS FROM CHRONICALLY HYPOXIC HYPERTENSIVE CALVES (TERMED PH-FIBS) EXPRESSED A CONSTITUTIVE AND PERSISTENT PROINFLAMMATORY PHENOTYPE DEFINED BY HIGH EXPRESSION OF IL-1BETA, IL-6, CCL2(MCP-1), CXCL12(SDF-1), CCL5(RANTES), CCR7, CXCR4, GM-CSF, CD40, CD40L, AND VCAM-1. THE PROINFLAMMATORY PHENOTYPE OF PH-FIBS WAS ASSOCIATED WITH EPIGENETIC ALTERATIONS AS DEMONSTRATED BY INCREASED ACTIVITY OF HDACS AND THE FINDINGS THAT CLASS I HDAC INHIBITORS MARKEDLY DECREASED CYTOKINE/CHEMOKINE MRNA EXPRESSION LEVELS IN THESE CELLS. PH-FIBS INDUCED INCREASED ADHESION OF THP-1 MONOCYTES AND PRODUCED SOLUBLE FACTORS THAT INDUCED INCREASED MIGRATION OF THP-1 AND MURINE BONE MARROW-DERIVED MACROPHAGES AS WELL AS ACTIVATED MONOCYTES/MACROPHAGES TO EXPRESS PROINFLAMMATORY CYTOKINES AND PROFIBROGENIC MEDIATORS (TIMP1 AND TYPE I COLLAGEN) AT THE TRANSCRIPTIONAL LEVEL. CLASS I HDAC INHIBITORS MARKEDLY REDUCED THE ABILITY OF PH-FIBS TO INDUCE MONOCYTE MIGRATION AND PROINFLAMMATORY ACTIVATION. THE EMERGENCE OF A DISTINCT ADVENTITIAL FIBROBLAST POPULATION WITH AN EPIGENETICALLY ALTERED PROINFLAMMATORY PHENOTYPE CAPABLE OF RECRUITING, RETAINING, AND ACTIVATING MONOCYTES/MACROPHAGES CHARACTERIZES PULMONARY HYPERTENSION-ASSOCIATED VASCULAR REMODELING AND THUS COULD CONTRIBUTE SIGNIFICANTLY TO CHRONIC INFLAMMATORY PROCESSES IN THE PULMONARY ARTERY WALL. 2011 20 2370 26 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