1 4050 149 MALADAPTIVE TRAINED IMMUNITY AND CLONAL HEMATOPOIESIS AS POTENTIAL MECHANISTIC LINKS BETWEEN PERIODONTITIS AND INFLAMMATORY COMORBIDITIES. PERIODONTITIS IS BIDIRECTIONALLY ASSOCIATED WITH SYSTEMIC INFLAMMATORY DISORDERS. THE PREVALENCE AND SEVERITY OF THIS ORAL DISEASE AND LINKED COMORBIDITIES INCREASES WITH AGING. HERE, WE REVIEW TWO NEWLY EMERGED CONCEPTS, TRAINED INNATE IMMUNITY (TII) AND CLONAL HEMATOPOIESIS OF INDETERMINATE POTENTIAL (CHIP), WHICH TOGETHER SUPPORT A POTENTIAL HYPOTHESIS ON HOW PERIODONTITIS AFFECTS AND IS AFFECTED BY COMORBIDITIES AND WHY THE SUSCEPTIBILITY TO PERIODONTITIS AND COMORBIDITIES INCREASES WITH AGING. GIVEN THAT CHRONIC DISEASES ARE LARGELY TRIGGERED BY THE ACTION OF INFLAMMATORY IMMUNE CELLS, MODULATION OF THEIR BONE MARROW PRECURSORS, THE HEMATOPOIETIC STEM AND PROGENITOR CELLS (HSPCS), MAY AFFECT MULTIPLE DISORDERS THAT EMERGE AS COMORBIDITIES. SUCH ALTERATIONS IN HSPCS CAN BE MEDIATED BY TII AND/OR CHIP, TWO NON-MUTUALLY EXCLUSIVE PROCESSES SHARING A BIAS FOR ENHANCED MYELOPOIESIS AND PRODUCTION OF INNATE IMMUNE CELLS WITH HEIGHTENED PROINFLAMMATORY POTENTIAL. TII IS A STATE OF ELEVATED IMMUNE RESPONSIVENESS BASED ON INNATE IMMUNE (EPIGENETIC) MEMORY. SYSTEMIC INFLAMMATION CAN INITIATE TII IN THE BONE MARROW VIA SUSTAINED REWIRING OF HSPCS, WHICH THEREBY DISPLAY A SKEWING TOWARD THE MYELOID LINEAGE, RESULTING IN GENERATION OF HYPER-REACTIVE OR "TRAINED" MYELOID CELLS. CHIP ARISES FROM AGING-RELATED SOMATIC MUTATIONS IN HSPCS, WHICH CONFER A SURVIVAL AND PROLIFERATION ADVANTAGE TO THE MUTANT HSPCS AND GIVE RISE TO AN OUTSIZED FRACTION OF HYPER-INFLAMMATORY MUTANT MYELOID CELLS IN THE CIRCULATION AND TISSUES. THIS REVIEW DISCUSSES EMERGING EVIDENCE THAT SUPPORTS THE NOTION THAT TII AND CHIP MAY UNDERLIE A CAUSAL AND AGE-RELATED ASSOCIATION BETWEEN PERIODONTITIS AND COMORBIDITIES. A HOLISTIC MECHANISTIC UNDERSTANDING OF THE PERIODONTITIS-SYSTEMIC DISEASE CONNECTION MAY OFFER NOVEL DIAGNOSTIC AND THERAPEUTIC TARGETS FOR TREATING INFLAMMATORY COMORBIDITIES. 2022 2 6520 48 TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF MONOCYTE AND MACROPHAGE DYSFUNCTION BY CHRONIC ALCOHOL CONSUMPTION. DRINKING ALCOHOL, EVEN IN MODERATION, CAN AFFECT THE IMMUNE SYSTEM. STUDIES HAVE SHOWN DISPROPORTIONATE EFFECTS OF ALCOHOL ON CIRCULATING AND TISSUE-RESIDENT MYELOID CELLS (GRANULOCYTES, MONOCYTES, MACROPHAGES, DENDRITIC CELLS). THESE CELLS ORCHESTRATE THE BODY'S FIRST LINE OF DEFENSE AGAINST MICROBIAL CHALLENGES AS WELL AS MAINTAIN TISSUE HOMEOSTASIS AND REPAIR. ALCOHOL'S EFFECTS ON THESE CELLS ARE DEPENDENT ON EXPOSURE PATTERN, WITH ACUTE DRINKING DAMPENING BUT CHRONIC DRINKING ENHANCING PRODUCTION OF INFLAMMATORY MEDIATORS. ALTHOUGH CHRONIC DRINKING IS ASSOCIATED WITH HEIGHTENED SYSTEMIC INFLAMMATION, STUDIES ON TISSUE RESIDENT MACROPHAGE POPULATIONS IN SEVERAL ORGANS INCLUDING THE SPLEEN, LIVER, BRAIN, AND LUNG HAVE ALSO SHOWN COMPROMISED FUNCTIONAL AND METABOLIC CAPACITIES OF THESE CELLS. MANY OF THESE EFFECTS ARE THOUGHT TO BE MEDIATED BY OXIDATIVE STRESS CAUSED BY ALCOHOL AND ITS METABOLITES WHICH CAN DIRECTLY IMPACT THE CELLULAR EPIGENETIC LANDSCAPES. IN ADDITION, SINCE MYELOID CELLS ARE RELATIVELY SHORT-LIVED IN CIRCULATION AND ARE UNDER CONSTANT REPOPULATION FROM THE BONE MARROW COMPARTMENT, ALCOHOL'S EFFECTS ON BONE MARROW PROGENITORS AND HEMATOPOIESIS ARE IMPORTANT FOR UNDERSTANDING THE IMPACT OF ALCOHOL SYSTEMICALLY ON THESE MYELOID POPULATIONS. ALCOHOL-INDUCED DISRUPTION OF PROGENITOR, CIRCULATING, AND TISSUE RESIDENT MYELOID POPULATIONS CONTRIBUTE TO THE INCREASED SUSCEPTIBILITY OF PATIENTS WITH ALCOHOL USE DISORDERS TO VIRAL AND BACTERIAL INFECTIONS. IN THIS REVIEW, WE PROVIDE AN OVERVIEW OF THE IMPACT OF CHRONIC ALCOHOL CONSUMPTION ON THE FUNCTION OF MONOCYTES AND MACROPHAGES IN HOST DEFENSE, TISSUE REPAIR AND INFLAMMATION. WE THEN SUMMARIZE OUR CURRENT UNDERSTANDING OF THE MECHANISMS UNDERLYING ALCOHOL-INDUCED DISRUPTION AND EXAMINE CHANGES IN TRANSCRIPTOME AND EPIGENOME OF MONOCYTES AND MCROPHAGES. OVERALL, CHRONIC ALCOHOL CONSUMPTION LEADS TO HYPER-INFLAMMATION CONCOMITANT WITH DECREASED MICROBIAL AND WOUND HEALING RESPONSES BY MONOCYTES/MACROPHAGES DUE TO A REWIRING OF THE EPIGENTIC AND TRANSCRIPTIONAL LANDSCAPE. HOWEVER, IN ADVANCED ALCOHOLIC LIVER DISEASE, MYELOID CELLS BECOME IMMUNOSUPPRESSED AS A RESPONSE TO THE SURROUNDING HYPER-INFLAMMATORY MILIEU. THEREFORE, THE EFFECT OF CHRONIC ALCOHOL ON THE INFLAMMATORY RESPONSE DEPENDS ON DISEASE STATE AND THE IMMUNE CELL POPULATION. 2022 3 3651 36 INCREASING COMPLEXITY OF MOLECULAR LANDSCAPES IN HUMAN HEMATOPOIETIC STEM AND PROGENITOR CELLS DURING DEVELOPMENT AND AGING. THE PAST FIVE DECADES HAVE SEEN SIGNIFICANT PROGRESS IN OUR UNDERSTANDING OF HUMAN HEMATOPOIESIS. THIS HAS IN PART BEEN DUE TO THE UNPRECEDENTED DEVELOPMENT OF ADVANCED TECHNOLOGIES, WHICH HAVE ALLOWED THE IDENTIFICATION AND CHARACTERIZATION OF RARE SUBSETS OF HUMAN HEMATOPOIETIC STEM AND PROGENITOR CELLS AND THEIR LINEAGE TRAJECTORIES FROM EMBRYONIC THROUGH TO ADULT LIFE. ADDITIONALLY, SURROGATE IN VITRO AND IN VIVO MODELS, ALTHOUGH NOT FULLY RECAPITULATING HUMAN HEMATOPOIESIS, HAVE SPURRED ON THESE SCIENTIFIC ADVANCES. THESE APPROACHES HAVE HEIGHTENED OUR KNOWLEDGE OF HEMATOLOGICAL DISORDERS AND DISEASES AND HAVE LED TO THEIR IMPROVED DIAGNOSIS AND THERAPIES. HERE, WE REVIEW HUMAN HEMATOPOIESIS AT EACH END OF THE AGE SPECTRUM, DURING EMBRYONIC AND FETAL DEVELOPMENT AND ON AGING, PROVIDING EXEMPLARS OF RECENT PROGRESS IN DECIPHERING THE INCREASINGLY COMPLEX CELLULAR AND MOLECULAR HEMATOPOIETIC LANDSCAPES IN HEALTH AND DISEASE. THIS REVIEW CONCLUDES BY HIGHLIGHTING LINKS BETWEEN CHRONIC INFLAMMATION AND METABOLIC AND EPIGENETIC CHANGES ASSOCIATED WITH AGING AND IN THE DEVELOPMENT OF CLONAL HEMATOPOIESIS. 2022 4 5428 34 REGULATION OF STRESS-INDUCED HEMATOPOIESIS. PURPOSE OF REVIEW: THE HEMATOPOIETIC COMPARTMENT IS TASKED WITH THE ESTABLISHMENT AND MAINTENANCE OF THE ENTIRE BLOOD PROGRAM IN STEADY-STATE AND IN RESPONSE TO STRESS. KEY TO THIS PROCESS ARE HEMATOPOIETIC STEM CELLS (HSCS), WHICH POSSESS THE UNIQUE ABILITY TO SELF-RENEW AND DIFFERENTIATE TO REPLENISH BLOOD CELLS THROUGHOUT AN ORGANISM'S LIFETIME. THOUGH TIGHTLY REGULATED, THE HEMATOPOIETIC SYSTEM IS VULNERABLE TO BOTH INTRINSIC AND EXTRINSIC FACTORS THAT INFLUENCE HEMATOPOIETIC STEM AND PROGENITOR CELL (HSPC) FATE. HERE, WE REVIEW RECENT ADVANCES IN OUR UNDERSTANDING OF HEMATOPOIETIC REGULATION UNDER STRESS CONDITIONS SUCH AS INFLAMMATION, AGING, MITOCHONDRIAL DEFECTS, AND DAMAGE TO DNA OR ENDOPLASMIC RETICULUM. RECENT FINDINGS: RECENT STUDIES HAVE ILLUSTRATED THE VAST MECHANISMS INVOLVED IN REGULATING STRESS-INDUCED HEMATOPOIESIS, INCLUDING CYTOKINE-MEDIATED LINEAGE BIAS, GENE SIGNATURE CHANGES IN AGED HSCS ASSOCIATED WITH CHRONIC INFLAMMATION, THE IMPACT OF CLONAL HEMATOPOIESIS AND STRESS TOLERANCE, CHARACTERIZATION OF THE HSPC RESPONSE TO ENDOPLASMIC RETICULUM STRESS AND OF SEVERAL EPIGENETIC REGULATORS THAT INFLUENCE HSPC RESPONSE TO CELL CYCLE STRESS. SUMMARY: SEVERAL KEY RECENT FINDINGS HAVE DEEPENED OUR UNDERSTANDING OF STRESS HEMATOPOIESIS. THESE STUDIES WILL ADVANCE OUR ABILITIES TO REDUCE THE IMPACT OF STRESS IN DISEASE AND AGING THROUGH CLINICAL INTERVENTIONS TO TREAT STRESS-RELATED OUTCOMES. 2020 5 928 31 CHRONIC INFLAMMATION, THE TUMOR MICROENVIRONMENT AND CARCINOGENESIS. CHRONIC INFLAMMATION OFTEN PRECEDES OR ACCOMPANIES A SUBSTANTIAL NUMBER OF CANCERS. INDEED, ANTI-INFLAMMATORY THERAPIES HAVE SHOWN EFFICACY IN CANCER PREVENTION AND TREATMENT. THE EXACT MECHANISMS THAT TURN A WOUND HEALING PROCESS INTO A CANCER PRECURSOR ARE TOPICS OF INTENSE RESEARCH. A PATHOGENIC LINK HAS BEEN IDENTIFIED BETWEEN INFLAMMATORY MEDIATORS, INFLAMMATION RELATED GENE POLYMORPHISMS AND CARCINOGENESIS. ANIMAL MODELS OF CANCER HAVE BEEN INSTRUMENTAL IN DEMONSTRATING THE DIVERSITY OF MECHANISMS THROUGH WHICH EVERY TUMOR COMPARTMENT AND TUMOR STAGE MAY BE AFFECTED BY THE UNDERLYING INFLAMMATORY PROCESS. IN THIS REVIEW, WE FOCUS ON THE INTERACTION BETWEEN CHRONIC INFLAMMATION, TUMOR STEM CELLS AND THE TUMOR MICROENVIRONMENT. WE SUMMARIZE THE PROPOSED MECHANISMS THAT LEAD TO THE RECRUITMENT OF BONE MARROW DERIVED CELLS AND EXPLORE THE GENETIC AND EPIGENETIC ALTERATIONS THAT MAY OCCUR IN INFLAMMATION ASSOCIATED CANCERS. 2009 6 5412 38 REGULATION OF ANTITUMOR IMMUNITY BY INFLAMMATION-INDUCED EPIGENETIC ALTERATIONS. CHRONIC INFLAMMATION PROMOTES TUMOR DEVELOPMENT, PROGRESSION, AND METASTATIC DISSEMINATION AND CAUSES TREATMENT RESISTANCE. THE ACCUMULATION OF GENETIC ALTERATIONS AND LOSS OF NORMAL CELLULAR REGULATORY PROCESSES ARE NOT ONLY ASSOCIATED WITH CANCER GROWTH AND PROGRESSION BUT ALSO RESULT IN THE EXPRESSION OF TUMOR-SPECIFIC AND TUMOR-ASSOCIATED ANTIGENS THAT MAY ACTIVATE ANTITUMOR IMMUNITY. THIS ANTAGONISM BETWEEN INFLAMMATION AND IMMUNITY AND THE ABILITY OF CANCER CELLS TO AVOID IMMUNE DETECTION AFFECT THE COURSE OF CANCER DEVELOPMENT AND TREATMENT OUTCOMES. WHILE INFLAMMATION, PARTICULARLY ACUTE INFLAMMATION, SUPPORTS T-CELL PRIMING, ACTIVATION, AND INFILTRATION INTO INFECTED TISSUES, CHRONIC INFLAMMATION IS MOSTLY IMMUNOSUPPRESSIVE. HOWEVER, THE MAIN MECHANISMS THAT DICTATE THE OUTCOME OF THE INFLAMMATION-IMMUNITY INTERPLAY ARE NOT WELL UNDERSTOOD. RECENT DATA SUGGEST THAT INFLAMMATION TRIGGERS EPIGENETIC ALTERATIONS IN CANCER CELLS AND COMPONENTS OF THE TUMOR MICROENVIRONMENT. THESE ALTERATIONS CAN AFFECT AND MODULATE NUMEROUS ASPECTS OF CANCER DEVELOPMENT, INCLUDING TUMOR GROWTH, THE METABOLIC STATE, METASTATIC SPREAD, IMMUNE ESCAPE, AND IMMUNOSUPPRESSIVE OR IMMUNOSUPPORTIVE LEUKOCYTE GENERATION. IN THIS REVIEW, WE DISCUSS THE ROLE OF INFLAMMATION IN INITIATING EPIGENETIC ALTERATIONS IN IMMUNE CELLS, CANCER-ASSOCIATED FIBROBLASTS, AND CANCER CELLS AND SUGGEST HOW AND WHEN EPIGENETIC INTERVENTIONS CAN BE COMBINED WITH IMMUNOTHERAPIES TO IMPROVE THERAPEUTIC OUTCOMES. 2022 7 3732 34 INNATE IMMUNE MEMORY AND THE HOST RESPONSE TO INFECTION. UNLIKE THE ADAPTIVE IMMUNE SYSTEM, THE INNATE IMMUNE SYSTEM HAS CLASSICALLY BEEN CHARACTERIZED AS BEING DEVOID OF MEMORY FUNCTIONS. HOWEVER, RECENT RESEARCH SHOWS THAT INNATE MYELOID AND LYMPHOID CELLS HAVE THE ABILITY TO RETAIN MEMORY OF PRIOR PATHOGEN EXPOSURE AND BECOME PRIMED TO ELICIT A ROBUST, BROAD-SPECTRUM RESPONSE TO SUBSEQUENT INFECTION. THIS PHENOMENON HAS BEEN TERMED INNATE IMMUNE MEMORY OR TRAINED IMMUNITY. INNATE IMMUNE MEMORY IS INDUCED VIA ACTIVATION OF PATTERN RECOGNITION RECEPTORS AND THE ACTIONS OF CYTOKINES ON HEMATOPOIETIC PROGENITORS AND STEM CELLS IN BONE MARROW AND INNATE LEUKOCYTES IN THE PERIPHERY. THE TRAINED PHENOTYPE IS INDUCED AND SUSTAINED VIA EPIGENETIC MODIFICATIONS THAT REPROGRAM TRANSCRIPTIONAL PATTERNS AND METABOLISM. THESE MODIFICATIONS AUGMENT ANTIMICROBIAL FUNCTIONS, SUCH AS LEUKOCYTE EXPANSION, CHEMOTAXIS, PHAGOCYTOSIS, AND MICROBIAL KILLING, TO FACILITATE AN AUGMENTED HOST RESPONSE TO INFECTION. ALTERNATIVELY, INNATE IMMUNE MEMORY MAY CONTRIBUTE TO THE PATHOGENESIS OF CHRONIC DISEASES, SUCH AS ATHEROSCLEROSIS AND ALZHEIMER'S DISEASE. 2022 8 5765 29 SOURCE OF CHRONIC INFLAMMATION IN AGING. AGING IS A COMPLEX PROCESS THAT RESULTS FROM A COMBINATION OF ENVIRONMENTAL, GENETIC, AND EPIGENETIC FACTORS. A CHRONIC PRO-INFLAMMATORY STATUS IS A PERVASIVE FEATURE OF AGING. THIS CHRONIC LOW-GRADE INFLAMMATION OCCURRING IN THE ABSENCE OF OVERT INFECTION HAS BEEN DEFINED AS "INFLAMMAGING" AND REPRESENTS A SIGNIFICANT RISK FACTOR FOR MORBIDITY AND MORTALITY IN THE ELDERLY. THE LOW-GRADE INFLAMMATION PERSISTS EVEN AFTER REVERSING PRO-INFLAMMATORY STIMULI SUCH AS LDL CHOLESTEROL AND THE RENIN-ANGIOTENSIN SYSTEM (RAS). RECENTLY, SEVERAL POSSIBLE SOURCES OF CHRONIC LOW-GRADE INFLAMMATION OBSERVED DURING AGING AND AGE-RELATED DISEASES HAVE BEEN PROPOSED. CELL SENESCENCE AND DYSREGULATION OF INNATE IMMUNITY IS ONE SUCH MECHANISM BY WHICH PERSISTENT PROLONGED INFLAMMATION OCCURS EVEN AFTER THE INITIAL STIMULUS HAS BEEN REMOVED. ADDITIONALLY, THE COAGULATION FACTOR THAT ACTIVATES INFLAMMATORY SIGNALING BEYOND ITS ROLE IN THE COAGULATION SYSTEM HAS BEEN IDENTIFIED. THIS SIGNAL COULD BE A NEW SOURCE OF CHRONIC INFLAMMATION AND CELL SENESCENCE. HERE, WE SUMMARIZED THE FACTORS AND CELLULAR PATHWAYS/PROCESSES THAT ARE KNOWN TO REGULATE LOW-GRADE PERSISTENT INFLAMMATION IN AGING AND AGE-RELATED DISEASE. 2018 9 9 45 'TRAINED IMMUNITY': CONSEQUENCES FOR LYMPHOID MALIGNANCIES. IN HEMATOLOGICAL MALIGNANCIES COMPLEX INTERACTIONS EXIST BETWEEN THE IMMUNE SYSTEM, MICROORGANISMS AND MALIGNANT CELLS. ON ONE HAND, MICROORGANISMS CAN INDUCE CANCER, AS ILLUSTRATED BY SPECIFIC INFECTION-INDUCED LYMPHOPROLIFERATIVE DISEASES SUCH AS HELICOBACTER PYLORI-ASSOCIATED GASTRIC MUCOSA-ASSOCIATED LYMPHOID TISSUE LYMPHOMA. ON THE OTHER HAND, MALIGNANT CELLS CREATE AN IMMUNOSUPPRESSIVE ENVIRONMENT FOR THEIR OWN BENEFIT, BUT THIS ALSO RESULTS IN AN INCREASED RISK OF INFECTIONS. DISRUPTED INNATE IMMUNITY CONTRIBUTES TO THE NEOPLASTIC TRANSFORMATION OF BLOOD CELLS BY SEVERAL MECHANISMS, INCLUDING THE UNCONTROLLED CLEARANCE OF MICROBIAL AND AUTOANTIGENS RESULTING IN CHRONIC IMMUNE STIMULATION AND PROLIFERATION, CHRONIC INFLAMMATION, AND DEFECTIVE IMMUNE SURVEILLANCE AND ANTI-CANCER IMMUNITY. RESTORING DYSFUNCTION OR ENHANCING RESPONSIVENESS OF THE INNATE IMMUNE SYSTEM MIGHT THEREFORE REPRESENT A NEW ANGLE FOR THE PREVENTION AND TREATMENT OF HEMATOLOGICAL MALIGNANCIES, IN PARTICULAR LYMPHOID MALIGNANCIES AND ASSOCIATED INFECTIONS. RECENTLY, IT HAS BEEN SHOWN THAT CELLS OF THE INNATE IMMUNE SYSTEM, SUCH AS MONOCYTES/MACROPHAGES AND NATURAL KILLER CELLS, HARBOR FEATURES OF IMMUNOLOGICAL MEMORY AND DISPLAY ENHANCED FUNCTIONALITY LONG-TERM AFTER STIMULATION WITH CERTAIN MICROORGANISMS AND VACCINES. THESE FUNCTIONAL CHANGES RELY ON EPIGENETIC REPROGRAMMING AND HAVE BEEN TERMED 'TRAINED IMMUNITY'. IN THIS REVIEW THE CONCEPT OF 'TRAINED IMMUNITY' IS DISCUSSED IN THE SETTING OF LYMPHOID MALIGNANCIES. AMELIORATION OF INFECTIOUS COMPLICATIONS AND HEMATOLOGICAL DISEASE PROGRESSION CAN BE ENVISIONED TO RESULT FROM THE INDUCTION OF TRAINED IMMUNITY, BUT FUTURE STUDIES ARE REQUIRED TO PROVE THIS EXCITING NEW HYPOTHESIS. 2016 10 6497 42 TRAINED IMMUNITY IN ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. TRAINED IMMUNITY, ALSO KNOWN AS INNATE IMMUNE MEMORY, IS A PERSISTENT HYPER-RESPONSIVE FUNCTIONAL STATE OF INNATE IMMUNE CELLS. ACCUMULATING EVIDENCE IMPLICATES TRAINED IMMUNITY AS AN UNDERLYING MECHANISM OF CHRONIC INFLAMMATION IN ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. IN THIS CONTEXT, TRAINED IMMUNITY IS INDUCED BY ENDOGENOUS ATHEROSCLEROSIS-PROMOTING FACTORS, SUCH AS MODIFIED LIPOPROTEINS OR HYPERGLYCAEMIA, CAUSING BROAD METABOLIC AND EPIGENETIC REPROGRAMMING OF THE MYELOID CELL COMPARTMENT. IN ADDITION TO TRADITIONAL CARDIOVASCULAR RISK FACTORS, LIFESTYLE FACTORS, INCLUDING UNHEALTHY DIETS, SEDENTARY LIFESTYLE, SLEEP DEPRIVATION AND PSYCHOSOCIAL STRESS, AS WELL AS INFLAMMATORY COMORBIDITIES, HAVE BEEN SHOWN TO ACTIVATE TRAINED IMMUNITY-LIKE MECHANISMS IN BONE MARROW HAEMATOPOIETIC STEM CELLS. IN THIS REVIEW, WE DISCUSS THE MOLECULAR AND CELLULAR MECHANISMS OF TRAINED IMMUNITY, ITS SYSTEMIC REGULATION THROUGH HAEMATOPOIETIC PROGENITOR CELLS IN THE BONE MARROW, AND THE ACTIVATION OF THESE MECHANISMS BY CARDIOVASCULAR DISEASE RISK FACTORS. WE ALSO HIGHLIGHT OTHER TRAINED IMMUNITY FEATURES THAT ARE RELEVANT FOR ATHEROSCLEROTIC CARDIOVASCULAR DISEASE, INCLUDING THE DIVERSE CELL TYPES THAT SHOW MEMORY CHARACTERISTICS AND TRANSGENERATIONAL INHERITANCE OF TRAINED IMMUNITY TRAITS. FINALLY, WE PROPOSE POTENTIAL STRATEGIES FOR THE THERAPEUTIC MODULATION OF TRAINED IMMUNITY TO MANAGE ATHEROSCLEROTIC CARDIOVASCULAR DISEASE. 2023 11 5003 47 PERIODONTITIS IS AN INFLAMMATORY DISEASE OF OXIDATIVE STRESS: WE SHOULD TREAT IT THAT WAY. PERIODONTITIS IS A HIGHLY PREVALENT DISEASE. AS IT PROGRESSES, IT CAUSES SERIOUS MORBIDITY IN THE FORM OF PERIODONTAL ABSCESSES AND TOOTH LOSS AND, IN THE LATTER STAGES, PAIN. IT IS ALSO NOW KNOWN THAT PERIODONTITIS IS STRONGLY ASSOCIATED WITH SEVERAL NONORAL DISEASES. THUS, PATIENTS WITH PERIODONTITIS ARE AT GREATER RISK FOR THE DEVELOPMENT AND/OR EXACERBATION OF DIABETES, CHRONIC OBSTRUCTIVE PULMONARY DISEASE, AND CARDIOVASCULAR DISEASES, AMONG OTHER CONDITIONS. ALTHOUGH IT IS WITHOUT QUESTION THAT SPECIFIC GROUPS OF ORAL BACTERIA WHICH POPULATE DENTAL PLAQUE PLAY A CAUSATIVE ROLE IN THE DEVELOPMENT OF PERIODONTITIS, IT IS NOW THOUGHT THAT ONCE THIS DISEASE HAS BEEN TRIGGERED, OTHER FACTORS PLAY AN EQUAL, AND POSSIBLY MORE IMPORTANT, ROLE IN ITS PROGRESSION, PARTICULARLY IN SEVERE CASES OR IN CASES THAT PROVE DIFFICULT TO TREAT. IN THIS REGARD, WE ALLUDE TO THE HOST RESPONSE, SPECIFICALLY THE NOTION THAT THE HOST, ONCE INFECTED WITH ORAL PERIODONTAL PATHOGENIC BACTERIA, WILL MOUNT A DEFENSE RESPONSE MEDIATED LARGELY THROUGH THE INNATE IMMUNE SYSTEM. THE MOST ABUNDANT CELL TYPE OF THE INNATE IMMUNE SYSTEM - POLYMORPHONUCLEAR NEUTROPHILS - CAN, WHEN PROTECTING THE HOST FROM MICROBIAL INVASION, MOUNT A RESPONSE THAT INCLUDES UPREGULATION OF PROINFLAMMATORY CYTOKINES, MATRIX METALLOPROTEINASES, AND REACTIVE OXYGEN SPECIES, ALL OF WHICH THEN CONTRIBUTE TO THE TISSUE DAMAGE AND LOSS OF TEETH COMMONLY ASSOCIATED WITH PERIODONTITIS. OF THE MECHANISMS REFERRED TO HERE, WE SUGGEST THAT UPREGULATION OF REACTIVE OXYGEN SPECIES MIGHT PLAY ONE OF THE MOST IMPORTANT ROLES IN THE ESTABLISHMENT AND PROGRESSION OF PERIODONTITIS (AS WELL AS IN OTHER DISEASES OF INFLAMMATION) THROUGH THE DEVELOPMENT OF OXIDATIVE STRESS. IN THIS OVERVIEW, WE DISCUSS BOTH INNATE AND EPIGENETIC FACTORS (EG, DIABETES, SMOKING) THAT LEAD TO THE DEVELOPMENT OF OXIDATIVE STRESS. THIS OXIDATIVE STRESS THEN PROVIDES AN ENVIRONMENT CONDUCIVE TO THE DESTRUCTIVE PROCESSES OBSERVED IN PERIODONTITIS. THEREFORE, WE SHALL DESCRIBE SOME OF THE FUNDAMENTAL CHARACTERISTICS OF OXIDATIVE STRESS AND ITS EFFECTS ON THE PERIODONTIUM, DISCUSS THE DISEASES AND OTHER FACTORS THAT CAUSE OXIDATIVE STRESS, AND, FINALLY, REVIEW POTENTIALLY NOVEL THERAPEUTIC APPROACHES FOR THE MANAGEMENT (AND POSSIBLY EVEN THE REVERSAL) OF PERIODONTITIS, WHICH RELY ON THE USE OF THERAPIES, SUCH AS RESVERATROL AND OTHER ANTIOXIDANTS, THAT PROVIDE INCREASED ANTIOXIDANT ACTIVITY IN THE HOST. 2020 12 4200 39 METABOLIC REQUIREMENTS OF TH17 CELLS AND OF B CELLS: REGULATION AND DEFECTS IN HEALTH AND IN INFLAMMATORY DISEASES. THE IMMUNE SYSTEM PROTECTS FROM INFECTIONS AND CANCER THROUGH COMPLEX CELLULAR NETWORKS. FOR THIS PURPOSE, IMMUNE CELLS REQUIRE WELL-DEVELOPED MECHANISMS OF ENERGY GENERATION. HOWEVER, THE IMMUNE SYSTEM ITSELF CAN ALSO CAUSE DISEASES WHEN DEFECTIVE REGULATION RESULTS IN THE EMERGENCE OF AUTOREACTIVE LYMPHOCYTES. RECENT STUDIES PROVIDE INSIGHTS INTO HOW DIFFERENTIAL PATTERNS OF IMMUNE CELL RESPONSES ARE ASSOCIATED WITH SELECTIVE METABOLIC PATHWAYS. THIS REVIEW WILL EXAMINE THE CHANGING METABOLIC REQUIREMENTS OF TH17 CELLS AND OF B CELLS AT DIFFERENT STAGES OF THEIR DEVELOPMENT AND ACTIVATION. BOTH CELLS PROVIDE PROTECTION BUT CAN ALSO MEDIATE DISEASES THROUGH THE PRODUCTION OF AUTOANTIBODIES AND THE PRODUCTION OF PROINFLAMMATORY MEDIATORS. IN HEALTH, B CELLS PRODUCE ANTIBODIES AND CYTOKINES AND PRESENT ANTIGENS TO T CELLS TO MOUNT SPECIFIC IMMUNITY. TH17 CELLS, ON THE OTHER HAND, PROVIDE PROTECTION AGAINST EXTRA CELLULAR PATHOGENS AT MUCOSAL SURFACES BUT CAN ALSO DRIVE CHRONIC INFLAMMATION. THE LATTER CELLS CAN ALSO PROMOTE THE DIFFERENTIATION OF B CELLS TO PLASMA CELLS TO PRODUCE MORE AUTOANTIBODIES. METABOLISM-REGULATED CHECKPOINTS AT DIFFERENT STAGES OF THEIR DEVELOPMENT ENSURE THE THAT SELF-REACTIVE B CELLS CLONES AND NEEDLESS PRODUCTION OF INTERLEUKIN (IL-)17 ARE LIMITED. THE METABOLIC REGULATION OF THE TWO CELL TYPES HAS SOME SIMILARITIES, E.G. THE UTILITY OF HYPOXIA INDUCED FACTOR (HIF)1ALPHA DURING LOW OXYGEN TENSION, TO PREVENT AUTOIMMUNITY AND REGULATE INFLAMMATION. THERE ARE ALSO CLEAR DIFFERENCES, AS TH17 CELLS ONLY ARE VULNERABLE TO THE LACK OF CERTAIN AMINO ACIDS. B CELLS, UNLIKE TH17 CELLS, ARE ALSO DEPENDENT OF MECHANISTIC TARGET OF RAPAMYCIN 2 (MTORC2) TO FUNCTION. SIGNIFICANT KNOWLEDGE HAS RECENTLY BEEN GAINED, PARTICULARLY ON TH17 CELLS, ON HOW METABOLISM REGULATES THESE CELLS THROUGH INFLUENCING THEIR EPIGENOME. METABOLIC DYSREGULATION OF TH17 CELLS AND B CELLS CAN LEAD TO CHRONIC INFLAMMATION. DISEASE ASSOCIATED ALTERATIONS IN THE GENOME CAN, IN ADDITION, CAUSE DYSREGULATION TO METABOLISM AND, THEREBY, RESULT IN EPIGENETIC ALTERATIONS IN THESE CELLS. RECENT STUDIES HIGHLIGHT HOW PATHOLOGY CAN RESULT FROM THE COOPERATION BETWEEN THE TWO CELL TYPES BUT ONLY FEW HAVE SO FAR ADDRESSED THE KEY METABOLIC ALTERATIONS IN SUCH SETTINGS. KNOWLEDGE OF THE IMPACT OF METABOLIC DYSFUNCTION ON CHRONIC INFLAMMATION AND PATHOLOGY CAN REVEAL NOVEL THERAPEUTIC TARGETS TO TREAT SUCH DISEASES. 2022 13 3703 30 INFLAMMATORY SIGNALLING AS MEDIATOR OF EPIGENETIC MODULATION IN TISSUE-SPECIFIC CHRONIC INFLAMMATION. RECENT SUCCESSES OF THERAPEUTIC INTERVENTION IN CHRONIC INFLAMMATORY DISEASES USING EPIGENETIC MODIFIERS SUCH AS HISTONE DEACETYLASE INHIBITORS AND INHIBITORS OF DNA METHYLATION SUGGEST THAT EPIGENETIC REPROGRAMMING PLAYS A ROLE IN THE AETIOLOGY OF THESE DISEASES. THE EPIGENETIC SIGNATURE OF A GIVEN IMMUNE CELL IS REFLECTED IN THE HISTORY OF MODIFICATIONS FROM DIFFERENT SIGNALS THE CELL HAS BEEN SUBJECTED TO DURING DIFFERENTIATION. LIKE OTHER CELLS, DIFFERENTIATING IMMUNE CELLS ARE DEPENDENT ON A COMPLEX COMBINATION OF INTER- AND INTRACELL SIGNALLING AS WELL AS TRANSCRIPTION MACHINERIES TO MODULATE THEIR EPIGENOMES IN ORDER TO MEDIATE DIFFERENTIATION. DESPITE EXTENSIVE RESEARCH INTO THESE PROCESSES, THE LINK BETWEEN CELLULAR SIGNALLING AND EPIGENETIC MODULATION REMAINS POORLY UNDERSTOOD. HERE, WE REVIEW RECENT PROGRESS AND DISCUSS KEY FACTORS DRIVING EPIGENETIC MODULATION IN CHRONIC INFLAMMATION. 2009 14 5581 33 ROLE OF NF-KAPPAB IN AGEING AND AGE-RELATED DISEASES: LESSONS FROM GENETICALLY MODIFIED MOUSE MODELS. AGEING IS A COMPLEX PROCESS, INDUCED BY MULTIFACETED INTERACTION OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS. IT IS MANIFESTED BY A DECLINE IN THE PHYSIOLOGICAL FUNCTIONS OF ORGANISMS AND ASSOCIATED TO THE DEVELOPMENT OF AGE-RELATED CHRONIC DISEASES AND CANCER DEVELOPMENT. IT IS CONSIDERED THAT AGEING FOLLOWS A STRICTLY-REGULATED PROGRAM, IN WHICH SOME SIGNALING PATHWAYS CRITICALLY CONTRIBUTE TO THE ESTABLISHMENT AND MAINTENANCE OF THE AGED STATE. CHRONIC INFLAMMATION IS A MAJOR MECHANISM THAT PROMOTES THE BIOLOGICAL AGEING PROCESS AND COMORBIDITY, WITH THE TRANSCRIPTION FACTOR NF-KAPPAB (NUCLEAR FACTOR KAPPA-LIGHT-CHAIN-ENHANCER OF ACTIVATED B CELLS) AS A CRUCIAL MEDIATOR OF INFLAMMATORY RESPONSES. THIS, TOGETHER WITH THE FINDING THAT THE ACTIVATION OR INHIBITION OF NF-KAPPAB CAN INDUCE OR REVERSE RESPECTIVELY THE MAIN FEATURES OF AGED ORGANISMS, HAS BROUGHT IT UNDER CONSIDERATION AS A KEY TRANSCRIPTION FACTOR THAT ACTS AS A DRIVER OF AGEING. IN THIS REVIEW, WE FOCUSED ON THE DATA OBTAINED ENTIRELY THROUGH THE GENERATION OF KNOCKOUT AND TRANSGENIC MOUSE MODELS OF EITHER PROTEIN INVOLVED IN THE NF-KAPPAB SIGNALING PATHWAY THAT HAVE PROVIDED RELEVANT INFORMATION ABOUT THE INTRICATE PROCESSES OR MOLECULAR MECHANISMS THAT CONTROL AGEING. WE HAVE REVIEWED THE RELATIONSHIP OF NF-KAPPAB AND PREMATURE AGEING; THE DEVELOPMENT OF CANCER ASSOCIATED WITH AGEING AND THE IMPLICATION OF NF-KAPPAB ACTIVATION IN THE DEVELOPMENT OF AGE-RELATED DISEASES, SOME OF WHICH GREATLY INCREASE THE RISK OF DEVELOPING CANCER. 2021 15 4043 30 MACROPHAGES IN CHRONIC LIVER FAILURE: DIVERSITY, PLASTICITY AND THERAPEUTIC TARGETING. CHRONIC LIVER INJURY RESULTS IN IMMUNE-DRIVEN PROGRESSIVE FIBROSIS, WITH RISK OF CIRRHOSIS DEVELOPMENT AND IMPACT ON MORBIDITY AND MORTALITY. PERSISTENT LIVER CELL DAMAGE AND DEATH CAUSES IMMUNE CELL ACTIVATION AND INFLAMMATION. PATIENTS WITH ADVANCED CIRRHOSIS ADDITIONALLY EXPERIENCE PATHOLOGICAL BACTERIAL TRANSLOCATION, EXPOSURE TO MICROBIAL PRODUCTS AND CHRONIC ENGAGEMENT OF THE IMMUNE SYSTEM. BACTERIAL INFECTIONS HAVE A HIGH INCIDENCE IN CIRRHOSIS, WITH SPONTANEOUS BACTERIAL PERITONITIS BEING THE MOST COMMON, WHILE THE SUBSEQUENT SYSTEMIC INFLAMMATION, ORGAN FAILURE AND IMMUNE DYSREGULATION INCREASE THE MORTALITY RISK. TISSUE-RESIDENT AND RECRUITED MACROPHAGES PLAY A CENTRAL PART IN THE DEVELOPMENT OF INFLAMMATION AND FIBROSIS PROGRESSION. IN THE LIVER, ADIPOSE TISSUE, PERITONEUM AND INTESTINES, DIVERSE MACROPHAGE POPULATIONS EXHIBIT GREAT PHENOTYPIC AND FUNCTIONAL PLASTICITY DETERMINED BY THEIR ONTOGENY, EPIGENETIC PROGRAMMING AND LOCAL MICROENVIRONMENT. THESE CHANGES CAN, AT DIFFERENT TIMES, PROMOTE OR AMELIORATE DISEASE STATES AND THEREFORE REPRESENT POTENTIAL TARGETS FOR MACROPHAGE-DIRECTED THERAPIES. IN THIS REVIEW, WE DISCUSS THE EVIDENCE FOR MACROPHAGE PHENOTYPIC AND FUNCTIONAL ALTERATIONS IN TISSUE COMPARTMENTS DURING THE DEVELOPMENT AND PROGRESSION OF CHRONIC LIVER FAILURE IN DIFFERENT AETIOLOGIES AND HIGHLIGHT THE POTENTIAL OF MACROPHAGE MODULATION AS A THERAPEUTIC STRATEGY FOR LIVER DISEASE. 2021 16 5913 24 TARGETED THERAPY IN LEUKEMIA. RESEARCH CONDUCTED OVER THE LAST TWO DECADES HAS YIELDED A DETAILED UNDERSTANDING OF THE MOLECULAR LESIONS THAT CONTRIBUTE TO THE MALIGNANT TRANSFORMATION OF HEMATOPOIETIC STEM CELLS AND COMMITTED PROGENITORS INTO THE VARIOUS FORMS OF ACUTE AND CHRONIC LEUKEMIA. ALTHOUGH OUR UNDERSTANDING OF THE MOLECULAR PATHOLOGY OF LEUKEMIA REMAINS INCOMPLETE, THE INFORMATION GAINED TO DATE HAS HAD A PROFOUND IMPACT ON THE WAY THESE MALIGNANCIES ARE BOTH DIAGNOSED AND MONITORED DURING THERAPY. MORE RECENTLY, TARGETED THERAPIES HAVE BEEN DEVELOPED AGAINST SOME OF THE IDENTIFIED GENETIC LESIONS. THESE THERAPIES HAVE LED TO SIGNIFICANT IMPROVEMENTS IN PATIENT OUTCOMES WHILE SIMULTANEOUSLY DECREASING THERAPY-RELATED TOXICITY. WITH THE ADVENT OF GENOME-WIDE METHODS TO DEFINE THE TOTAL COMPLEMENT OF GENETIC AND EPIGENETIC LESIONS INVOLVED IN LEUKEMOGENESIS, NEW TARGETED THERAPIES CAN BE ANTICIPATED. THIS REVIEW HIGHLIGHTS SOME OF THE TARGETED THERAPIES THAT ARE PRESENTLY BEING USED TO TREAT HEMATOPOIETIC MALIGNANCIES AND DESCRIBES SOME OF THE RECENT ADVANCES THAT SHOULD HAVE A SIGNIFICANT IMPACT ON THE DEVELOPMENT OF FUTURE TARGET THERAPIES. 2008 17 2036 26 EPIGENETIC CHANGES OF THE IMMUNE SYSTEM WITH ROLE IN TUMOR DEVELOPMENT. TUMOR DEVELOPMENT IS CLOSELY RELATED TO CHRONIC INFLAMMATION AND TO EVASION OF IMMUNE DEFENSE MECHANISMS BY NEOPLASTIC CELLS. THE MEDIATORS OF THE INFLAMMATORY PROCESS AS WELL AS PROTEINS INVOLVED IN IMMUNE RESPONSE OR IMMUNE RESPONSE EVASION CAN BE SUBJECT TO VARIOUS EPIGENETIC CHANGES SUCH AS METHYLATION, ACETYLATION, OR PHOSPHORYLATION. SOME OF THESE, SUCH AS CYTOKINE SUPPRESSORS, ARE UNDERGOING REPRESSION THROUGH EPIGENETIC CHANGES, AND OTHERS SUCH AS CYTOKINES OR CHEMOKINES ARE UNDERGOING ACTIVATION THROUGH EPIGENETIC CHANGES, BOTH MODIFICATIONS HAVING AS A RESULT TUMOR PROGRESSION. THE ACTIVATING CHANGES CAN AFFECT THE RECEPTOR MOLECULES INVOLVED IN IMMUNE RESPONSE AND THESE PROMOTE INFLAMMATION AND SUBSEQUENTLY TUMOR DEVELOPMENT WHILE THE INACTIVATING CHANGES SEEM TO BE RELATED TO THE TUMOR REGRESSION PROCESS. THE PROTEINS INVOLVED IN ANTIGEN PRESENTATION, AND, THEREFORE IN IMMUNE RESPONSE ESCAPE, SUCH AS CLASSICAL HLA PROTEINS AND RELATED APM (ANTIGEN PRESENTATION MACHINERY) WITH THEIR EPIGENETIC CHANGES CONTRIBUTE TO THE TUMOR DEVELOPMENT PROCESS, EITHER TO TUMOR PROGRESSION OR REGRESSION, DEPENDING ON THE IMMUNE EFFECTOR CELLS THAT ARE IN PLAY. 2018 18 6135 38 THE EPIGENETICS OF INFLAMMAGING: THE CONTRIBUTION OF AGE-RELATED HETEROCHROMATIN LOSS AND LOCUS-SPECIFIC REMODELLING AND THE MODULATION BY ENVIRONMENTAL STIMULI. A GROWING AMOUNT OF EVIDENCES INDICATES THAT INFLAMMAGING - THE CHRONIC, LOW GRADE INFLAMMATION STATE CHARACTERISTIC OF THE ELDERLY - IS THE RESULT OF GENETIC AS WELL AS ENVIRONMENTAL OR STOCHASTIC FACTORS. SOME OF THESE, SUCH AS THE ACCUMULATION OF SENESCENT CELLS THAT ARE PERSISTENT DURING AGING OR ACCOMPANY ITS PROGRESSION, SEEM TO BE SUFFICIENT TO INITIATE THE AGING PROCESS AND TO FUEL IT. OTHERS, LIKE EXPOSURE TO ENVIRONMENTAL COMPOUNDS OR INFECTIONS, ARE TEMPORARY AND RESOLVE WITHIN A (RELATIVELY) SHORT TIME. IN BOTH CASES, HOWEVER, A CELLULAR MEMORY OF THE EVENT CAN BE ESTABLISHED BY MEANS OF EPIGENETIC MODULATION OF THE GENOME. IN THIS REVIEW WE WILL SPECIFICALLY DISCUSS THE RELATIONSHIP BETWEEN EPIGENETICS AND INFLAMMAGING. IN PARTICULAR, WE WILL SHOW HOW AGE-ASSOCIATED EPIGENETIC MODIFICATIONS CONCERNED WITH HETEROCHROMATIN LOSS AND GENE-SPECIFIC REMODELLING, CAN PROMOTE INFLAMMAGING. FURTHERMORE, WE WILL RECALL HOW THE EXPOSURE TO SPECIFIC NUTRITIONAL, ENVIRONMENTAL AND MICROBIAL STIMULI CAN AFFECT THE RATE OF INFLAMMAGING THROUGH EPIGENETIC MECHANISMS, TOUCHING ALSO ON THE RECENT INSIGHT GIVEN BY THE CONCEPT OF TRAINED IMMUNITY. 2018 19 2558 37 EPIGENETICS IN SUSCEPTIBILITY, PROGRESSION, AND DIAGNOSIS OF PERIODONTITIS. PERIODONTITIS IS CHARACTERIZED BY IRREVERSIBLE DESTRUCTION OF PERIODONTAL TISSUE. AT PRESENT, THE ACCEPTED ETIOLOGY OF PERIODONTITIS IS BASED ON A THREE-FACTOR THEORY INCLUDING PATHOGENIC BACTERIA, HOST FACTORS, AND ACQUIRED FACTORS. PERIODONTITIS DEVELOPMENT USUALLY TAKES A DECADE OR LONGER AND IS THEREFORE CALLED CHRONIC PERIODONTITIS (CP). TO SEARCH FOR GENETIC FACTORS ASSOCIATED WITH CP, SEVERAL GENOME-WIDE ASSOCIATION STUDY (GWAS) ANALYSES WERE CONDUCTED; HOWEVER, POLYMORPHISMS ASSOCIATED WITH CP HAVE NOT BEEN IDENTIFIED. EPIGENETICS, ON THE OTHER HAND, INVOLVES ACQUIRED TRANSCRIPTIONAL REGULATORY MECHANISMS DUE TO REVERSIBLY ALTERED CHROMATIN ACCESSIBILITY. EPIGENETIC STATUS IS A CONDITION SPECIFIC TO EACH TISSUE AND CELL, MOSTLY DETERMINED BY THE RESPONSES OF HOST CELLS TO STIMULATIONS BY LOCAL FACTORS, LIKE BACTERIAL INFLAMMATION, AND SYSTEMIC FACTORS SUCH AS NUTRITION STATUS, METABOLIC DISEASES, AND HEALTH CONDITIONS. SIGNIFICANTLY, EPIGENETIC STATUS HAS BEEN LINKED WITH THE ONSET AND PROGRESSION OF SEVERAL ACQUIRED DISEASES. THUS, EPIGENETIC FACTORS IN PERIODONTAL TISSUES ARE ATTRACTIVE TARGETS FOR PERIODONTITIS DIAGNOSIS AND TREATMENTS. IN THIS REVIEW, WE INTRODUCE ACCUMULATING EVIDENCE TO REVEAL THE EPIGENETIC BACKGROUND EFFECTS RELATED TO PERIODONTITIS CAUSED BY GENETIC FACTORS, SYSTEMIC DISEASES, AND LOCAL ENVIRONMENTAL FACTORS, SUCH AS SMOKING, AND CLARIFY THE UNDERLYING MECHANISMS BY WHICH EPIGENETIC ALTERATION INFLUENCES THE SUSCEPTIBILITY OF PERIODONTITIS. 2022 20 733 32 CANCER EPIGENETICS: LINKING BASIC BIOLOGY TO CLINICAL MEDICINE. CANCER EVOLUTION AT ALL STAGES IS DRIVEN BY BOTH EPIGENETIC ABNORMALITIES AS WELL AS GENETIC ALTERATIONS. DYSREGULATION OF EPIGENETIC CONTROL EVENTS MAY LEAD TO ABNORMAL PATTERNS OF DNA METHYLATION AND CHROMATIN CONFIGURATIONS, BOTH OF WHICH ARE CRITICAL CONTRIBUTORS TO THE PATHOGENESIS OF CANCER. THESE EPIGENETIC ABNORMALITIES ARE SET AND MAINTAINED BY MULTIPLE PROTEIN COMPLEXES AND THE INTERPLAY BETWEEN THEIR INDIVIDUAL COMPONENTS INCLUDING DNA METHYLATION MACHINERY, HISTONE MODIFIERS, PARTICULARLY, POLYCOMB (PCG) PROTEINS, AND CHROMATIN REMODELING PROTEINS. RECENT ADVANCES IN GENOME-WIDE TECHNOLOGY HAVE REVEALED THAT THE INVOLVEMENT OF THESE DYSREGULATED EPIGENETIC COMPONENTS APPEARS TO BE EXTENSIVE. MOREOVER, THERE IS A GROWING CONNECTION BETWEEN EPIGENETIC ABNORMALITIES IN CANCER AND CONCEPTS CONCERNING STEM-LIKE CELL SUBPOPULATIONS AS A DRIVING FORCE FOR CANCER. EMERGING DATA SUGGEST THAT ASPECTS OF THE EPIGENETIC LANDSCAPE INHERENT TO NORMAL EMBRYONIC AND ADULT STEM/PROGENITOR CELLS MAY HELP FOSTER, UNDER THE STRESS OF CHRONIC INFLAMMATION OR ACCUMULATING REACTIVE OXYGEN SPECIES, EVOLUTION OF MALIGNANT SUBPOPULATIONS. FINALLY, UNDERSTANDING MOLECULAR MECHANISMS INVOLVED IN INITIATION AND MAINTENANCE OF EPIGENETIC ABNORMALITIES IN ALL TYPES OF CANCER HAS GREAT POTENTIAL FOR TRANSLATIONAL PURPOSES. THIS IS ALREADY EVIDENT FOR EPIGENETIC BIOMARKER DEVELOPMENT, AND FOR PHARMACOLOGICAL TARGETING AIMED AT REVERSING CANCER-SPECIFIC EPIGENETIC ALTERATIONS. 2011