1 4404 154 MODULATION OF THE RESPONSE TO MYCOBACTERIUM LEPRAE AND PATHOGENESIS OF LEPROSY. THE INITIAL INFECTION BY THE OBLIGATE INTRACELLULAR BACILLUS MYCOBACTERIUM LEPRAE EVOLVES TO LEPROSY IN A SMALL SUBSET OF THE INFECTED INDIVIDUALS. TRANSMISSION IS BELIEVED TO OCCUR MAINLY BY EXPOSURE TO BACILLI PRESENT IN AEROSOLS EXPELLED BY INFECTED INDIVIDUALS WITH HIGH BACILLARY LOAD. MYCOBACTERIUM LEPRAE-SPECIFIC DNA HAS BEEN DETECTED IN THE BLOOD OF ASYMPTOMATIC HOUSEHOLD CONTACTS OF LEPROSY PATIENTS YEARS BEFORE ACTIVE DISEASE ONSET, SUGGESTING THAT, FOLLOWING INFECTION, THE BACTERIUM REACHES THE LYMPHATIC DRAINAGE AND THE BLOOD OF AT LEAST SOME INDIVIDUALS. THE LOWER TEMPERATURE AND AVAILABILITY OF PROTECTED MICROENVIRONMENTS MAY PROVIDE THE INITIAL CONDITIONS FOR THE SURVIVAL OF THE BACILLUS IN THE AIRWAYS AND SKIN. A SUBSET OF SKIN-RESIDENT MACROPHAGES AND THE SCHWANN CELLS OF PERIPHERAL NERVES, TWO M. LEPRAE PERMISSIVE CELLS, MAY PROTECT M. LEPRAE FROM EFFECTOR CELLS IN THE INITIAL PHASE OF THE INFECTION. THE INTERACTION OF M. LEPRAE WITH THESE CELLS INDUCES METABOLIC CHANGES, INCLUDING THE FORMATION OF LIPID DROPLETS, THAT ARE ASSOCIATED WITH MACROPHAGE M2 PHENOTYPE AND THE PRODUCTION OF MEDIATORS THAT FACILITATE THE DIFFERENTIATION OF SPECIFIC T CELLS FOR M. LEPRAE-EXPRESSED ANTIGENS TO A MEMORY REGULATORY PHENOTYPE. HERE, WE DISCUSS THE POSSIBLE INITIALS STEPS OF M. LEPRAE INFECTION THAT MAY LEAD TO ACTIVE DISEASE ONSET, MAINLY FOCUSING ON EVENTS PRIOR TO THE MANIFESTATION OF THE ESTABLISHED CLINICAL FORMS OF LEPROSY. WE HYPOTHESIZE THAT THE PROGRESSIVE DIFFERENTIATION OF T CELLS TO THE TREGS PHENOTYPE INHIBITS EFFECTOR FUNCTION AGAINST THE BACILLUS, ALLOWING AN INCREASE IN THE BACILLARY LOAD AND EVOLUTION OF THE INFECTION TO ACTIVE DISEASE. EPIGENETIC AND METABOLIC MECHANISMS DESCRIBED IN OTHER CHRONIC INFLAMMATORY DISEASES ARE EVALUATED FOR POTENTIAL APPLICATION TO THE UNDERSTANDING OF LEPROSY PATHOGENESIS. A POTENTIAL ROLE FOR POST-EXPOSURE PROPHYLAXIS OF LEPROSY IN REDUCING M. LEPRAE-INDUCED ANTI-INFLAMMATORY MEDIATORS AND, IN CONSEQUENCE, TREG/T EFFECTOR RATIOS IS PROPOSED. 2022 2 3904 45 LEPROSY PIRNOME: EXPLORING NEW POSSIBILITIES FOR AN OLD DISEASE. LEPROSY, WHICH IS CAUSED BY THE HUMAN PATHOGEN MYCOBACTERIUM LEPRAE, CAUSES NERVE DAMAGE, DEFORMITY AND DISABILITY IN OVER 200,000 PEOPLE EVERY YEAR. BECAUSE OF THE LONG DOUBLING TIME OF M. LEPRAE (13 DAYS) AND THE DELAYED ONSET OF DETECTABLE SYMPTOMS, WHICH IS ESTIMATED TO BE APPROXIMATELY 3-7 YEARS AFTER INFECTION, THERE IS ALWAYS A LARGE PERCENTAGE OF SUBCLINICALLY INFECTED INDIVIDUALS IN THE POPULATION WHO WILL EVENTUALLY DEVELOP THE DISEASE, MAINLY IN ENDEMIC COUNTRIES. PIRNAS COMPRISE THE LARGEST GROUP OF SMALL NONCODING RNAS FOUND IN HUMANS, AND THEY ARE DISTINCT FROM MICRORNAS (MIRNAS) AND SMALL INTERFERING RNAS (SIRNAS). PIRNAS FUNCTION IN TRANSPOSON SILENCING, EPIGENETIC REGULATION, AND GERMLINE DEVELOPMENT. THE FUNCTIONAL ROLE OF PIRNAS AND THEIR ASSOCIATED PIWI PROTEINS HAVE STARTED TO EMERGE IN THE DEVELOPMENT OF HUMAN CANCERS AND VIRAL INFECTIONS, BUT THEIR RELEVANCE TO BACTERIAL DISEASES HAS NOT BEEN INVESTIGATED. THE PRESENT STUDY REPORTS THE PIRNOME OF HUMAN SKIN, REVEALING THAT ALL BUT ONE OF THE PIRNAS EXAMINED ARE DOWNREGULATED IN LEPROSY SKIN LESIONS. CONSIDERING THAT ONE OF THE BEST CHARACTERIZED FUNCTIONS OF PIRNAS IN HUMANS IS POSTTRANSCRIPTIONAL MRNA SILENCING, THEIR FUNCTIONS ARE SIMILAR TO WHAT WE HAVE DESCRIBED FOR MIRNAS, INCLUDING ACTING ON APOPTOSIS, M. LEPRAE RECOGNITION AND ENGULFMENT, SCHWANN CELL (SC) DEMYELINATION, EPITHELIAL-MESENCHYMAL TRANSITION (EMT), LOSS OF SENSATION AND NEUROPATHIC PAIN. IN ADDITION TO NEW FINDINGS ON LEPROSY PHYSIOPATHOLOGY, THE DISCOVERY OF RELEVANT PIRNAS INVOLVED IN DISEASE PROCESSES IN HUMAN SKIN MAY PROVIDE NEW CLUES FOR THERAPEUTIC TARGETS, SPECIFICALLY TO CONTROL NERVE DAMAGE, A PROMINENT FEATURE OF LEPROSY THAT HAS NO CURRENTLY AVAILABLE PHARMACEUTICAL TREATMENT. 2020 3 5800 28 STEPWISE PATHOGENIC EVOLUTION OF MYCOBACTERIUM ABSCESSUS. ALTHOUGH ALMOST ALL MYCOBACTERIAL SPECIES ARE SAPROPHYTIC ENVIRONMENTAL ORGANISMS, A FEW, SUCH AS MYCOBACTERIUM TUBERCULOSIS, HAVE EVOLVED TO CAUSE TRANSMISSIBLE HUMAN INFECTION. BY ANALYZING THE RECENT EMERGENCE AND SPREAD OF THE ENVIRONMENTAL ORGANISM M. ABSCESSUS THROUGH THE GLOBAL CYSTIC FIBROSIS POPULATION, WE HAVE DEFINED KEY, GENERALIZABLE STEPS INVOLVED IN THE PATHOGENIC EVOLUTION OF MYCOBACTERIA. WE SHOW THAT EPIGENETIC MODIFIERS, ACQUIRED THROUGH HORIZONTAL GENE TRANSFER, CAUSE SALTATIONAL INCREASES IN THE PATHOGENIC POTENTIAL OF SPECIFIC ENVIRONMENTAL CLONES. ALLOPATRIC PARALLEL EVOLUTION DURING CHRONIC LUNG INFECTION THEN PROMOTES RAPID INCREASES IN VIRULENCE THROUGH MUTATIONS IN A DISCRETE GENE NETWORK; THESE MUTATIONS ENHANCE GROWTH WITHIN MACROPHAGES BUT IMPAIR FOMITE SURVIVAL. AS A CONSEQUENCE, WE OBSERVE CONSTRAINED PATHOGENIC EVOLUTION WHILE PERSON-TO-PERSON TRANSMISSION REMAINS INDIRECT, BUT POSTULATE ACCELERATED PATHOGENIC ADAPTATION ONCE DIRECT TRANSMISSION IS POSSIBLE, AS OBSERVED FOR M. TUBERCULOSIS OUR FINDINGS INDICATE HOW KEY INTERVENTIONS, SUCH AS EARLY TREATMENT AND CROSS-INFECTION CONTROL, MIGHT RESTRICT THE SPREAD OF EXISTING MYCOBACTERIAL PATHOGENS AND PREVENT NEW, EMERGENT ONES. 2021 4 389 30 AN INTEGRATIVE HYPOTHESIS LINKING CANCER, DIABETES AND ATHEROSCLEROSIS: THE ROLE OF MUTATIONS AND EPIGENETIC CHANGES. IT APPEARS THAT THE DISEASE STATES OF CANCER, ALTHEROSCLEROSIS AND DIABETES MIGHT SHARE A COMMON ETIOLOGY. THESE CHRONIC DISEASES APPEAR TO BE MULTI-STAGED IN THEIR PROGRESSION, WITH GENETIC, NUTRITIONAL, PSYCHO-SOCIAL, ENVIRONMENTAL AND VIRAL FACTORS INFLUENCING THEIR APPEARANCE. WE OFFERED A HYPOTHESIS (A "MUTATION THEORY OF DISEASE"), STATING THAT THESE DISEASES CAN BE DESCRIBED BY INITIATION AND PROMOTION PHASES; INITIATION BEING THE RESULT OF THE PRODUCTION OF MUTATED CELLS AFTER UNREPAIRED DAMAGED DNA IS REPLICATED; PROMOTION BEING THE SELECTIVE PROLIFERATION OF THE INITIATED CELLS TO FORM CLONES OF MUTATED CELLS. IT WAS FURTHER POSTULATED THAT PROMOTION AFFECTS CELL PROLIFERATION BY ALTERING A MEMBRANE-CA++ REGULATORY SYSTEM. DEPENDING ON THE NATURE OF THE MUTATION IN THE CLONE OF CELLS, SPECIFIC DISEASE STATES WOULD RESULT. THE ROLES OF RADIATIONS, CHEMICALS, VIRUSES, GENES, NUTRITION AND PSYCHO-SOCIAL STRESS WERE RELATED TO EITHER THE INITIATION (MUTATION PRODUCTION) OR THE PROMOTION (CELL PROLIFERATION) PHASE OF THESE DISEASES. 1980 5 3661 36 INDUCTION OF INNATE IMMUNE MEMORY BY ENGINEERED NANOPARTICLES IN MONOCYTES/MACROPHAGES: FROM HYPOTHESIS TO REALITY. THE CAPACITY OF ENGINEERED NANOPARTICLES TO ACTIVATE CELLS OF THE INNATE IMMUNE SYSTEM, IN PARTICULAR MONOCYTES AND MACROPHAGES, IS CONSIDERED AT THE BASIS OF THEIR TOXIC/INFLAMMATORY EFFECTS. IT IS, HOWEVER, EVIDENT THAT EVEN NANOPARTICLES THAT DO NOT DIRECTLY INDUCE INFLAMMATORY ACTIVATION, AND ARE THEREFORE CONSIDERED AS SAFE, CAN NEVERTHELESS INDUCE EPIGENETIC MODIFICATIONS AND AFFECT METABOLIC PATHWAYS IN MONOCYTES AND MACROPHAGES. SINCE EPIGENETIC AND METABOLIC CHANGES ARE THE MAIN MECHANISMS OF INNATE MEMORY, WE HAD PREVIOUSLY PROPOSED THAT NANOPARTICLES CAN INDUCE/MODULATE INNATE MEMORY, THAT IS, HAVE THE ABILITY OF SHAPING THE SECONDARY RESPONSE TO INFLAMMATORY CHALLENGES. IN LIGHT OF NEW DATA, IT IS NOW POSSIBLE TO SUPPORT THE ORIGINAL HYPOTHESIS AND SHOW THAT DIFFERENT TYPES OF NANOPARTICLES CAN BOTH DIRECTLY INDUCE INNATE MEMORY, PRIMING MACROPHAGES FOR A MORE POTENT RESPONSE TO SUBSEQUENT STIMULI, AND MODULATE BACTERIA-INDUCED MEMORY BY ATTENUATING THE PRIMING-INDUCED ENHANCEMENT. THIS EVIDENCE RAISES TWO IMPORTANT ISSUES. FIRST, IN ADDITION TO OVERT TOXIC/INFLAMMATORY EFFECTS, WE SHOULD CONSIDER EVALUATING THE CAPACITY TO INDUCE INNATE MEMORY AND THE RELATED EPIGENETIC AND METABOLIC CHANGES IN THE IMMUNOSAFETY ASSESSMENT OF NANOMATERIALS, SINCE MODULATION OF INNATE MEMORY MAY BE AT THE BASIS OF LONG-TERM UNWANTED IMMUNOLOGICAL EFFECTS. THE OTHER IMPORTANT CONSIDERATION IS THAT THIS CAPACITY OF NANOMATERIALS COULD OPEN A NEW AVENUE IN IMMUNOMODULATION AND THE POSSIBILITY OF USING ENGINEERED NANOMATERIALS FOR IMPROVING IMMUNE RESPONSES TO VACCINES AND RESISTANCE TO INFECTIONS, AND MODULATE ANOMALOUS IMMUNE/INFLAMMATORY REACTIONS IN CHRONIC INFLAMMATORY DISEASES, AUTOIMMUNITY, AND A RANGE OF OTHER IMMUNE-RELATED PATHOLOGIES. 2020 6 3418 26 HUMAN HEALTH CONSEQUENCES OF ENVIRONMENTALLY-MODULATED GENE EXPRESSION: POTENTIAL ROLES OF ELF-EMF INDUCED EPIGENETIC VERSUS MUTAGENIC MECHANISMS OF DISEASE. IN ORDER TO DETERMINE IF THERE MIGHT BE BIOLOGICAL AND HEALTH CONSEQUENCES AFTER EXPOSURES TO EXTREMELY-LOW FREQUENCY ELECTROMAGNETIC FIELDS (ELF-EMF), EITHER EXPERIMENTALLY OR EPIDEMIOLOGICALLY, MECHANISTIC UNDERSTANDING OF THE POTENTIAL MEANS BY WHICH ANY ENVIRONMENTAL AGENT CAN AFFECT CELLS IN A MULTICELLULAR ORGANISM HAS TO BE REVIEWED. THE GOAL OF THIS LIMITED REVIEW IS TO DEMONSTRATE THAT, WHILE THE PREVAILING PARADIGM OF THE ENVIRONMENTALLY-INDUCED ACUTE AND CHRONIC DISEASES INVOLVES EITHER CELL KILLING (CYTOTOXICITY) OR GENE/CHROMOSOME MUTATIONS (GENOTOXICITY), ALTERATION OF THE EXPRESSION OF GENETIC INFORMATION AT THE TRANSCRIPTIONAL (TURNING GENES "ON" OR "OFF"), TRANSLATIONAL (STABILIZING OR DE-STABILIZING THE GENETIC MESSAGE), OR POSTTRANSLATIONAL (ALTERING THE GENE PRODUCT OR PROTEIN) LEVELS HAS THE POTENTIAL TO CONTRIBUTE TO VARIOUS DISEASES. THIS LATTER MECHANISM, "EPIGENETIC" TOXICITY, UNLIKE THE FORMER TWO WHICH ARE IRREVERSIBLE, IS CHARACTERIZED BY THRESHOLD-LIKE ACTION, MULTIPLE BIOCHEMICAL PATHWAYS AND CHRONIC, REGULAR EXPOSURES TO BE EFFECTIVE. ULTIMATELY, EPIGENETIC TOXICANTS AFFECT ONE OF FOUR POTENTIAL CELL STATES, NAMELY ALTERATION OF CELL PROLIFERATION, CELL DIFFERENTIATION, PROGRAMMED CELL DEATH (APOPTOSIS) OR ADAPTIVE RESPONSES OF DIFFERENTIATED CELLS. 2000 7 3917 38 LINK BETWEEN CHRONIC INFLAMMATION AND HUMAN PAPILLOMAVIRUS-INDUCED CARCINOGENESIS (REVIEW). INFLAMMATION IS A DEFENSE STRATEGY AGAINST INVADING AGENTS AND HARMFUL MOLECULES THAT IS ACTIVATED IMMEDIATELY FOLLOWING A STIMULUS, AND INVOLVES THE RELEASE OF CYTOKINES AND CHEMOKINES, WHICH ACTIVATE THE INNATE IMMUNE RESPONSE. THESE MEDIATORS ACT TOGETHER TO INCREASE BLOOD FLOW AND VASCULAR PERMEABILITY, FACILITATING RECRUITMENT OF EFFECTOR CELLS TO THE SITE OF INJURY. FOLLOWING RESOLUTION OF THE INJURY AND REMOVAL OF THE STIMULUS, INFLAMMATION IS DISABLED, BUT IF THE STIMULUS PERSISTS, INFLAMMATION BECOMES CHRONIC AND IS STRONGLY ASSOCIATED WITH CANCER. THIS IS LIKELY TO BE DUE TO THE FACT THAT THE INFLAMMATION LEADS TO A WOUND THAT DOES NOT HEAL, REQUIRING A CONSTANT RENEWAL OF CELLS, WHICH INCREASES THE RISK OF NEOPLASTIC TRANSFORMATION. DEBRIS FROM PHAGOCYTOSIS, INCLUDING THE REACTIVE SPECIES OF OXYGEN AND NITROGEN THAT CAUSE DAMAGE TO DNA ALREADY DAMAGED BY THE LEUKOTRIENES AND PROSTAGLANDINS, HAS AN IMPACT ON INFLAMMATION AND VARIOUS CARCINOGENIC ROUTES. THERE IS AN ASSOCIATION BETWEEN CHRONIC INFLAMMATION, PERSISTENT INFECTION AND CANCER, WHERE ONCOGENIC ACTION IS MEDIATED BY AUTOCRINE AND PARACRINE SIGNALS, CAUSING CHANGES IN SOMATIC CELLS UNDER THE INFLUENCE OF THE MICROBIAL GENOME OR OF EPIGENETIC FACTORS. AMONG THE INFECTIOUS AGENTS ASSOCIATED WITH CANCER, CERTAIN GENOTYPES OF HUMAN PAPILLOMAVIRUS (HPV) STAND OUT. HPV IS RESPONSIBLE FOR VIRTUALLY ALL CASES OF CERVICAL CANCER AND A LOWER PROPORTION OF CANCERS OF THE VAGINA, VULVA, ANUS, PENIS AND A NUMBER OF EXTRAGENITAL CANCERS. IN THE PRESENT REVIEW, RECENT ADVANCES IN THE MECHANISMS INVOLVED IN THE INFLAMMATORY RESPONSE ARE PRESENTED WITH THEIR PARTICIPATION IN THE PROCESS OF CARCINOGENESIS, EMPHASIZING THE ROLE OF CHRONIC INFLAMMATION IN THE DEVELOPMENT OF HPV-INDUCED CERVICAL CANCER. 2015 8 127 23 A TRANSCRIPTIONAL PERSPECTIVE ON HUMAN MACROPHAGE BIOLOGY. MACROPHAGES ARE A MAJOR CELL TYPE IN TISSUE HOMEOSTASIS AND CONTRIBUTE TO BOTH PATHOLOGY AND RESOLUTION IN ALL ACUTE AND CHRONIC INFLAMMATORY DISEASES RANGING FROM INFECTIONS, CANCER, OBESITY, ATHEROSCLEROSIS, AUTOIMMUNE DISORDERS TO NEURODEGENERATIVE DISEASES SUCH AS ALZHEIMER'S DISEASE. THE CELLULAR AND FUNCTIONAL DIVERSITY OF MACROPHAGES DEPENDS UPON TIGHTLY REGULATED TRANSCRIPTION. THE INNATE IMMUNE SYSTEM IS UNDER PROFOUND EVOLUTIONARY SELECTION. THERE IS INCREASING RECOGNITION THAT HUMAN MACROPHAGE BIOLOGY DIFFERS VERY SIGNIFICANTLY FROM THAT OF COMMONLY STUDIED ANIMAL MODELS, WHICH THEREFORE CAN HAVE A LIMITED PREDICTIVE VALUE. HERE WE REPORT ON THE NEWEST FINDINGS ON TRANSCRIPTIONAL CONTROL OF MACROPHAGE ACTIVATION, AND HOW WE ENVISION INTEGRATING STUDIES ON TRANSCRIPTIONAL AND EPIGENETIC REGULATION, AND MORE CLASSICAL APPROACHES IN MURINE MODELS. MOREOVER, WE PROVIDE NEW INSIGHTS INTO HOW WE CAN LEARN ABOUT TRANSCRIPTIONAL REGULATION IN THE HUMAN SYSTEM FROM LARGER EFFORTS SUCH AS THE FANTOM (FUNCTIONAL ANNOTATION OF THE MAMMALIAN GENOME) CONSORTIUM. 2015 9 6136 36 THE EPIGENETICS OF MULTIPLE SCLEROSIS AND OTHER RELATED DISORDERS. MULTIPLE SCLEROSIS (MS) IS A DEMYELINATING DISEASE CHARACTERIZED BY CHRONIC INFLAMMATION OF THE CENTRAL NERVOUS SYSTEM (CNS) GRAY AND WHITE MATTER. ALTHOUGH THE CAUSE OF MS IS UNKNOWN, IT IS WIDELY APPRECIATED THAT INNATE AND ADAPTIVE IMMUNE PROCESSES CONTRIBUTE TO ITS PATHOGENESIS. THESE INCLUDE MICROGLIA/MACROPHAGE ACTIVATION, PRO-INFLAMMATORY T-CELL (TH1) RESPONSES AND HUMORAL RESPONSES. ADDITIONALLY, THERE IS EVIDENCE INDICATING THAT MS HAS A NEURODEGENERATIVE COMPONENT SINCE NEURONAL AND AXONAL LOSS OCCURS EVEN IN THE ABSENCE OF OVERT INFLAMMATION. THESE ASPECTS ALSO FORM THE RATIONALE FOR CLINICAL MANAGEMENT OF THE DISEASE. HOWEVER, THE CURRENTLY AVAILABLE THERAPIES TO CONTROL THE DISEASE ARE ONLY PARTIALLY EFFECTIVE AT BEST INDICATING THAT MORE EFFECTIVE THERAPEUTIC SOLUTIONS ARE URGENTLY NEEDED. IT IS APPRECIATED THAT IN THE IMMUNE-DRIVEN AND NEURODEGENERATIVE PROCESSES MS-SPECIFIC DEREGULATION OF GENE EXPRESSIONS AND RESULTING PROTEIN DYSFUNCTION ARE THOUGHT TO PLAY A CENTRAL ROLE. THESE DEVIATIONS IN GENE EXPRESSION PATTERNS CONTRIBUTE TO THE INFLAMMATORY RESPONSE IN THE CNS, AND TO NEURONAL OR AXONAL LOSS. EPIGENETIC MECHANISMS CONTROL TRANSCRIPTION OF MOST, IF NOT ALL GENES, IN NUCLEATED CELLS INCLUDING CELLS OF THE CNS AND IN HAEMATOPOIETIC CELLS. MS-SPECIFIC ALTERATIONS IN EPIGENETIC REGULATION OF GENE EXPRESSION MAY THEREFORE LIE AT THE HEART OF THE DEREGULATION OF GENE EXPRESSION IN MS. AS SUCH, EPIGENETIC MECHANISMS MOST LIKELY PLAY AN IMPORTANT ROLE IN DISEASE PATHOGENESIS. IN THIS REVIEW WE DISCUSS A ROLE FOR MS-SPECIFIC DEREGULATION OF EPIGENETIC FEATURES THAT CONTROL GENE EXPRESSION IN THE CNS AND IN THE PERIPHERY. FURTHERMORE, WE DISCUSS THE APPLICATION OF SMALL MOLECULE INHIBITORS THAT TARGET THE EPIGENETIC MACHINERY TO AMELIORATE DISEASE IN EXPERIMENTAL ANIMAL MODELS, INDICATING THAT SUCH APPROACHES MAY BE APPLICABLE TO MS PATIENTS. 2014 10 6496 48 TRAINED IMMUNITY CONTRIBUTION TO AUTOIMMUNE AND INFLAMMATORY DISORDERS. A DYSREGULATED IMMUNE RESPONSE TOWARD SELF-ANTIGENS CHARACTERIZES AUTOIMMUNE AND AUTOINFLAMMATORY (AIF) DISORDERS. AUTOANTIBODIES OR AUTOREACTIVE T CELLS CONTRIBUTE TO AUTOIMMUNE DISEASES, WHILE AUTOINFLAMMATION RESULTS FROM A HYPER-FUNCTIONAL INNATE IMMUNE SYSTEM. ASIDE FROM THEIR DIFFERENCES, MANY STUDIES SUGGEST THAT MONOCYTES AND MACROPHAGES (MO/MA) SIGNIFICANTLY CONTRIBUTE TO THE DEVELOPMENT OF BOTH TYPES OF DISEASE. MO/MA ARE INNATE IMMUNE CELLS THAT PROMOTE AN IMMUNE-MODULATORY, PRO-INFLAMMATORY, OR REPAIR RESPONSE DEPENDING ON THE MICROENVIRONMENT. HOWEVER, UNDERSTANDING THE CONTRIBUTION OF THESE CELLS TO DIFFERENT IMMUNE DISORDERS HAS BEEN DIFFICULT DUE TO THEIR HIGH FUNCTIONAL AND PHENOTYPIC PLASTICITY. SEVERAL FACTORS CAN INFLUENCE THE FUNCTION OF MO/MA UNDER THE LANDSCAPE OF AUTOIMMUNE/AUTOINFLAMMATORY DISEASES, SUCH AS GENETIC PREDISPOSITION, EPIGENETIC CHANGES, OR INFECTIONS. FOR INSTANCE, SOME VACCINES AND MICROORGANISMS CAN INDUCE EPIGENETIC CHANGES IN MO/MA, MODIFYING THEIR FUNCTIONAL RESPONSES. THIS PHENOMENON IS KNOWN AS TRAINED IMMUNITY. TRAINED IMMUNITY CAN BE MEDIATED BY MO/MA AND NK CELLS INDEPENDENTLY OF T AND B CELL FUNCTION. IT IS DEFINED AS THE ALTERED INNATE IMMUNE RESPONSE TO THE SAME OR DIFFERENT MICROORGANISMS DURING A SECOND ENCOUNTER. THE IMPROVEMENT IN CELL FUNCTION IS RELATED TO EPIGENETIC AND METABOLIC CHANGES THAT MODIFY GENE EXPRESSION. ALTHOUGH THE BENEFITS OF IMMUNE TRAINING HAVE BEEN HIGHLIGHTED IN A VACCINATION CONTEXT, THE EFFECTS OF THIS TYPE OF IMMUNE RESPONSE ON AUTOIMMUNITY AND CHRONIC INFLAMMATION STILL REMAIN CONTROVERSIAL. INDUCTION OF TRAINED IMMUNITY REPROGRAMS CELLULAR METABOLISM IN HEMATOPOIETIC STEM CELLS (HSCS), TRANSMITTING A MEMORY-LIKE PHENOTYPE TO THE CELLS. THUS, TRAINED MO/MA DERIVED FROM HSCS TYPICALLY PRESENT A METABOLIC SHIFT TOWARD GLYCOLYSIS, WHICH LEADS TO THE MODIFICATION OF THE CHROMATIN ARCHITECTURE. DURING TRAINED IMMUNITY, THE EPIGENETIC CHANGES FACILITATE THE SPECIFIC GENE EXPRESSION AFTER SECONDARY CHALLENGE WITH OTHER STIMULI. CONSEQUENTLY, THE ENHANCED PRO-INFLAMMATORY RESPONSE COULD CONTRIBUTE TO DEVELOPING OR MAINTAINING AUTOIMMUNE/AUTOINFLAMMATORY DISEASES. HOWEVER, THE PREDICTION OF THE OUTCOME IS NOT SIMPLE, AND OTHER STUDIES PROPOSE THAT TRAINED IMMUNITY CAN INDUCE A BENEFICIAL RESPONSE BOTH IN AIF AND AUTOIMMUNE CONDITIONS BY INDUCING ANTI-INFLAMMATORY RESPONSES. THIS ARTICLE DESCRIBES THE METABOLIC AND EPIGENETIC MECHANISMS INVOLVED IN TRAINED IMMUNITY THAT AFFECT MO/MA, CONTRAPOSING THE CONTROVERSIAL EVIDENCE ON HOW IT MAY IMPACT AUTOIMMUNE/AUTOINFLAMMATION CONDITIONS. 2022 11 761 35 CATEGORIZING THE CHARACTERISTICS OF HUMAN CARCINOGENS: A NEED FOR SPECIFICITY. THE INTERNATIONAL AGENCY FOR RESEARCH ON CANCER (IARC) HAS RECENTLY PROPOSED EMPLOYING "TEN KEY CHARACTERISTICS OF HUMAN CARCINOGENS" (TKCS) TO DETERMINE THE POTENTIAL OF AGENTS FOR HARMFUL EFFECTS. THE TKCS SEEM LIKELY TO CONFUSE THE UNSATISFACTORY CORRELATION FROM TESTING REGIMES THAT HAVE IGNORED THE DIFFERENCES EVIDENT WHEN CELLULAR CHANGES ARE COMPARED IN SHORT AND LONG-LIVED SPECIES, WITH THEIR VERY DIFFERENT STEM CELL AND SOMATIC CELL PHYLOGENIES. THE PROPOSED CHARACTERISTICS ARE SO BROAD THAT THEIR USE WILL LEAD TO AN INCREASE IN THE CURRENT UNACCEPTABLY HIGH RATE OF FALSE POSITIVES. IT COULD BE AN INFORMATIVE EXPERIMENT TO TAKE WELL-ESTABLISHED APPROVED THERAPEUTICS WITH WELL-KNOWN HUMAN SAFETY PROFILES AND TEST THEM AGAINST THIS NEW TKC PARADIGM. CANCERS ARE INITIATED AND DRIVEN BY HERITABLE AND TRANSIENT CHANGES IN GENE EXPRESSION, EXPAND CLONALLY, AND PROGRESS VIA ADDITIONAL ASSOCIATED ACQUIRED MUTATIONS AND EPIGENETIC ALTERATIONS THAT PROVIDE CELLS WITH AN EVOLUTIONARY ADVANTAGE. THE GENOTOXICITY TESTING PROTOCOLS CURRENTLY EMPLOYED AND REQUIRED BY REGULATION, EMPHASIZE TESTING FOR THE MUTATIONAL POTENTIAL OF THE TEST AGENT. TWO-YEAR, CHRONIC RODENT CANCER BIOASSAYS ARE INTENDED TO TEST FOR THE ENTIRE SPECTRUM OF CARCINOGENIC TRANSFORMATION. THE USE OF CYTOTOXIC DOSES CAUSING INCREASED, SUSTAINED CELL PROLIFERATION THAT FACILITATES ACCUMULATED GENETIC DAMAGE LEADS TO A HIGH FALSE-POSITIVE RATE OF TUMOR INDUCTION. CURRENT CANCER HAZARD ASSESSMENT PROTOCOLS AND WEIGHT-OF-THE-EVIDENCE ANALYSIS OF AGENT-SPECIFIC CANCER RISK ALIGN POORLY WITH THE PATHOGENESIS OF HUMAN CARCINOMA AND SO NEED MODERNIZATION AND IMPROVEMENT IN WAYS SUGGESTED HERE. 2021 12 4 29 "MIX OF MICS"- PHENOTYPIC AND BIOLOGICAL HETEROGENEITY OF "MULTIPOTENT" MUSCLE INTERSTITIAL CELLS (MICS). THE CAPACITY OF ADULT SKELETAL MUSCLE FOR REGENERATION APPEARS TO BE LIMITED, WITH PROGRESSIVE IMPAIRMENT IN REPAIR EFFICIENCY OF INJURED MUSCLES OBSERVED IN CHRONIC MUSCULAR DISORDERS AND DURING AGING. WHILE SATELLITE CELLS, THE COMMITTED ADULT MUSCLE STEM CELLS, ARE THE MAIN DIRECT CELL SOURCE SUPPORTING THE REGENERATIVE POTENTIAL OF ADULT SKELETAL MUSCLES, THE CHARACTERIZATION OF THE CELL TYPES AND SIGNALS THAT CONSTITUTE THE FUNCTIONAL "NICHE" OF SATELLITE CELLS IS CURRENTLY THE OBJECT OF INTENSE INVESTIGATION. RECENT STUDIES HAVE IDENTIFIED A FUNCTIONAL RELATIONSHIP BETWEEN SATELLITE CELLS AND VARIOUS CELL TYPES LOCATED IN KEY ANATOMICAL POSITION, SUCH AS THE INTERSTITIUM OF SKELETAL MUSCLES. THIS HETEROGENEOUS POPULATION OF MUSCLE INTERSTITIAL CELLS (MICS) APPEARS TO RETAIN AN INTRINSIC MULTIPOTENCY WITHIN THE MESODERMAL LINEAGE, AND THEIR DIRECT OR INDIRECT CONTRIBUTION TO MYOFIBER TURNOVER, REPAIR AND DEGENERATION HAS BEEN SUGGESTED BY MANY STUDIES THAT WILL BE REVIEWED HERE. GIVEN THE EXISTING GAP OF KNOWLEDGE ON LINEAGE IDENTITY AND FUNCTIONAL PROPERTIES OF MICS, THEIR DETAILED CHARACTERIZATION AT THE SINGLE CELL LEVEL HOLDS THE PROMISE TO PROVIDE KEY INSIGHT INTO THE COMPOSITION OF THIS HETEROGENEOUS POPULATION AND THE DYNAMIC TRANSITION THROUGH DISTINCT SUB-POPULATIONS IN HEALTHY, DISEASED AND AGING MUSCLES. THIS REVIEW PROVIDES AN OVERVIEW OF THE RESULTS OF VARIOUS STUDIES DESCRIBING THE PHENOTYPE AND THE FUNCTION OF CELLS ISOLATED FROM SKELETAL MUSCLE INTERSTITIUM, AND DISCUSSES THE IMPORTANCE OF SINGLE CELL TRANSCRIPTION PROFILING IN ORDER TO DECIPHER THE FUNCTIONAL AND PHENOTYPICAL HETEROGENEITY OF MUSCLE INTERSTITIAL CELLS (MICS). 2012 13 5130 27 POSTTRANSCRIPTIONAL GENE REGULATION: NOVEL PATHWAYS FOR GLUCOCORTICOIDS' ANTI-INFLAMMATORY ACTION. POSTTRANSCRIPTIONAL GENE REGULATION (PTR) IS A FUNDAMENTAL BIOLOGICAL PROCESS THAT INTEGRATES WITH THE MASTER TRANSCRIPTIONAL CONTROL OF GENE EXPRESSION, IN WAYS THAT ONLY IN THE LAST DECADE HAVE BEEN INCREASINGLY UNDERSTOOD [1, 2]. WHILE EPIGENETIC AND TRANSCRIPTIONAL EVENTS SHAPE CELL RESPONSE QUALITATIVELY, DECIDING THE PATTERN OF GENE EXPRESSION TO 'SWITCH ON OR OFF' IN RESPONSE TO ENDOGENOUS OR ENVIRONMENTAL TRIGGERS, THE KEY TASK OF PTR IS TO ACT AS A 'RHEOSTAT' AND RAPIDLY ADAPT THE CELLULAR RESPONSE BY PROVIDING THE APPROPRIATE AMPLITUDE AND TIMING TO THE PROTEIN EXPRESSION PATTERNS [3, 4]. THE PIVOTAL ROLE OF THIS MECHANISM COMES TO THE FOREFRONT IN INFLAMMATORY AND IMMUNE RESPONSE, WHERE THE CHANGES IN AMPLITUDE AND DURATION IN THE EXPRESSION OF DANGEROUS AND PROTECTIVE GENES ARE IN DELICATE BALANCE, AND ARE CRITICAL IN DETERMINING EITHER THE SUCCESSFUL RESOLUTION OF THE IMMUNE RESPONSE OR ITS CHRONIC OVEREXPRESSION [5]. THIS BRIEF REVIEW INTRODUCES MEMBERS OF THE MAIN CLASSES OF MOLECULES MEDIATING THE CYTOPLASMIC ARM OF GENE REGULATION, NAMELY RNA-BINDING PROTEINS AND MICRO-RNA (MIRNA), AND SUMMARIZES EXPERIMENTAL DATA THAT UNDERSCORE THE ROLE OF THESE MOLECULES IN THE PATHOPHYSIOLOGY OF CHRONIC INFLAMMATION, AS WELL AS THEIR PROMISING VALUE AS MECHANISMS CONVEYING THE ANTI-INFLAMMATORY EFFECT OF SYNTHETIC GLUCOCORTICOIDS. 2012 14 2563 29 EPIGENETICS IN TUBERCULOSIS: IMMUNOMODULATION OF HOST IMMUNE RESPONSE. TUBERCULOSIS IS A STERN, DIFFICULT TO TREAT CHRONIC INFECTION CAUSED BY ACID-FAST BACILLI THAT TEND TO TAKE A LONG TIME TO BE ERADICATED FROM THE HOST'S ENVIRONMENT. IT REQUIRES THE ACTION OF BOTH INNATE AND ADAPTIVE IMMUNE SYSTEMS BY THE HOST. THERE ARE VARIOUS PATTERN RECOGNITION RECEPTORS PRESENT ON IMMUNE CELLS, WHICH RECOGNIZE FOREIGN PATHOGENS OR ITS PRODUCT AND TRIGGER THE IMMUNE RESPONSE. THE EPIGENETIC MODIFICATION PLAYS A CRUCIAL ROLE IN TRIGGERING THE SUSCEPTIBILITY OF THE HOST TOWARDS THE PATHOGEN AND ACTIVATING THE HOST'S IMMUNE SYSTEM AGAINST THE INVADING PATHOGEN. IT ALTERS THE GENE EXPRESSION MODIFYING THE GENETIC MATERIAL OF THE HOST'S CELL. EPIGENETIC MODIFICATION SUCH AS HISTONE ACETYLATION, ALTERATION IN NON-CODING RNA, DNA METHYLATION AND ALTERATION IN MIRNA HAS BEEN STUDIED FOR THEIR INFLUENCE ON THE PATHOPHYSIOLOGY OF TUBERCULOSIS TO CONTROL THE SPREAD OF INFECTION. DESPITE SEVERAL STUDIES BEING CONDUCTED, MANY GAPS STILL EXIST. HEREIN, WE DISCUSS THE IMMUNOPATHOPHYSIOLOGICAL MECHANISM OF TUBERCULOSIS, THE ESSENTIALS OF EPIGENETICS AND THE RECENT ENCROACHMENT OF EPIGENETICS IN THE FIELD OF TUBERCULOSIS AND ITS INFLUENCE ON THE OUTCOME AND PATHOPHYSIOLOGY OF THE INFECTION. 2022 15 4204 32 METABOLISM, EPIGENETICS, AND CAUSAL INFERENCE IN HEART FAILURE. EUKARYOTES MUST BALANCE THE METABOLIC AND CELL DEATH ACTIONS OF MITOCHONDRIA VIA CONTROL OF GENE EXPRESSION AND CELL FATE BY CHROMATIN, THEREBY FUNCTIONALLY BINDING THE METABOLOME AND EPIGENOME. THIS INTERACTION HAS FAR-REACHING IMPLICATIONS FOR CHRONIC DISEASES IN HUMANS, THE MOST COMMON OF WHICH ARE THOSE OF THE CARDIOVASCULAR SYSTEM. THE MOST DEVASTATING CONSEQUENCE OF CARDIOVASCULAR DISEASE, HEART FAILURE, IS NOT A SINGLE DISEASE, DIAGNOSIS, OR ENDPOINT. HUMAN AND ANIMAL STUDIES HAVE REVEALED THAT, REGARDLESS OF ETIOLOGY AND SYMPTOMS, HEART FAILURE IS UNIVERSALLY ASSOCIATED WITH ABNORMAL METABOLISM AND GENE EXPRESSION - TO FRAME THIS AS CAUSE OR CONSEQUENCE, HOWEVER, MAY BE TO WRONGFOOT THE QUESTION. THIS ESSAY AIMS TO CHALLENGE CURRENT THINKING ON METABOLIC-EPIGENETIC CROSSTALK IN HEART FAILURE, PRESENTING HYPOTHESES FOR HOW CHRONIC DISEASES ARISE, TAKE HOLD, AND PERSIST. WE UNPACK ASSUMPTIONS ABOUT THE ORDER OF OPERATIONS FOR GENE EXPRESSION AND METABOLISM, EXPLORING RECENT FINDINGS IN NONCARDIAC SYSTEMS THAT LINK METABOLIC INTERMEDIATES DIRECTLY TO CHROMATIN REMODELING. LASTLY, WE DISCUSS POTENTIAL MECHANISMS BY WHICH CHROMATIN MAY SERVE AS A SUBSTRATE FOR METABOLIC MEMORY, AND HOW CHANGES IN CELLULAR TRANSCRIPTOMES (AND HENCE IN CELLULAR BEHAVIOR) IN RESPONSE TO STRESS CORRESPOND TO GLOBAL CHANGES IN CHROMATIN ACCESSIBILITY AND STRUCTURE. 2020 16 4200 44 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 17 5431 33 REGULATORY T CELLS: PATHOPHYSIOLOGICAL ROLES AND CLINICAL APPLICATIONS. INFLAMMATION AND IMMUNE RESPONSES AFTER TISSUE INJURY PLAY PIVOTAL ROLES IN THE RESOLUTION OF INFLAMMATION, TISSUE RECOVERY, FIBROSIS, AND REMODELING. REGULATORY T CELLS (TREGS) ARE RESPONSIBLE FOR IMMUNE TOLERANCE AND ARE USUALLY ACTIVATED IN SECONDARY LYMPHATIC TISSUES. ACTIVATED TREGS SUBSEQUENTLY REGULATE EFFECTOR T CELL AND DENDRITIC CELL ACTIVATION. FOR CLINICAL APPLICATIONS SUCH AS THE SUPPRESSION OF BOTH AUTOIMMUNE DISEASES AND THE REJECTION OF TRANSPLANTED ORGANS, METHODS TO GENERATE STABILIZED ANTIGEN-SPECIFIC TREGS ARE REQUIRED. FOR THIS PURPOSE, TRANSCRIPTIONAL AND EPIGENETIC REGULATION OF FOXP3 EXPRESSION HAS BEEN INVESTIGATED. IN ADDITION TO CONVENTIONAL TREGS, THERE ARE SOME TREGS THAT RESIDE IN TISSUES AND ARE CALLED TISSUE TREGS. TISSUE TREGS EXHIBIT TISSUE-SPECIFIC FUNCTIONS THAT CONTRIBUTE TO THE MAINTENANCE OF TISSUE HOMEOSTASIS AND REPAIR. SUCH TISSUE TREGS COULD ALSO BE USEFUL FOR TREG-BASED CELL THERAPY. WE RECENTLY DISCOVERED BRAIN TREGS THAT ACCUMULATE IN THE BRAIN DURING THE CHRONIC PHASE OF ISCHEMIC BRAIN INJURY. BRAIN TREGS RESEMBLE OTHER TISSUE TREGS, BUT ARE UNIQUE IN EXPRESSING NEURAL CELL-SPECIFIC GENES SUCH AS THE SEROTONIN RECEPTOR (HTR7); CONSEQUENTLY, BRAIN TREGS RESPOND TO SEROTONIN. HERE, WE DESCRIBE OUR EXPERIENCES IN THE USE OF TREGS TO SUPPRESS GRAFT-VERSUS-HOST DISEASE AND TO PROMOTE NEURAL RECOVERY AFTER STROKE. 2020 18 2338 30 EPIGENETIC REGULATION OF INFLAMMATORY SIGNALING AND INFLAMMATION-INDUCED CANCER. EPIGENETICS COMPRISE A DIVERSE ARRAY OF REVERSIBLE AND DYNAMIC MODIFICATIONS TO THE CELL'S GENOME WITHOUT IMPLICATING ANY DNA SEQUENCE ALTERATIONS. BOTH THE EXTERNAL ENVIRONMENT SURROUNDING THE ORGANISM, AS WELL AS THE INTERNAL MICROENVIRONMENT OF CELLS AND TISSUES, CONTRIBUTE TO THESE EPIGENETIC PROCESSES THAT PLAY CRITICAL ROLES IN CELL FATE SPECIFICATION AND ORGANISMAL DEVELOPMENT. ON THE OTHER HAND, DYSREGULATION OF EPIGENETIC ACTIVITIES CAN INITIATE AND SUSTAIN CARCINOGENESIS, WHICH IS OFTEN AUGMENTED BY INFLAMMATION. CHRONIC INFLAMMATION, ONE OF THE MAJOR HALLMARKS OF CANCER, STEMS FROM PROINFLAMMATORY CYTOKINES THAT ARE SECRETED BY TUMOR AND TUMOR-ASSOCIATED CELLS IN THE TUMOR MICROENVIRONMENT. AT THE SAME TIME, INFLAMMATORY SIGNALING CAN ESTABLISH POSITIVE AND NEGATIVE FEEDBACK CIRCUITS WITH CHROMATIN TO MODULATE CHANGES IN THE GLOBAL EPIGENETIC LANDSCAPE. IN THIS REVIEW, WE PROVIDE AN IN-DEPTH DISCUSSION OF THE INTERCONNECTED CROSSTALK BETWEEN EPIGENETICS AND INFLAMMATION, SPECIFICALLY HOW EPIGENETIC MECHANISMS AT DIFFERENT HIERARCHICAL LEVELS OF THE GENOME CONTROL INFLAMMATORY GENE TRANSCRIPTION, WHICH IN TURN ENACT CHANGES WITHIN THE CELL'S EPIGENOMIC PROFILE, ESPECIALLY IN THE CONTEXT OF INFLAMMATION-INDUCED CANCER. 2022 19 2022 39 EPIGENETIC CHANGES ASSOCIATED WITH DISEASE PROGRESSION IN A MOUSE MODEL OF CHILDHOOD ALLERGIC ASTHMA. DEVELOPMENT OF ASTHMA IN CHILDHOOD IS LINKED TO VIRAL INFECTIONS OF THE LOWER RESPIRATORY TRACT IN EARLY LIFE, WITH SUBSEQUENT CHRONIC EXPOSURE TO ALLERGENS. PROGRESSION TO PERSISTENT ASTHMA IS ASSOCIATED WITH A TH2-BIASED IMMUNOLOGICAL RESPONSE AND STRUCTURAL REMODELLING OF THE AIRWAYS. THE UNDERLYING MECHANISMS ARE UNCLEAR, BUT COULD INVOLVE EPIGENETIC CHANGES. TO INVESTIGATE THIS, WE EMPLOYED A RECENTLY DEVELOPED MOUSE MODEL IN WHICH SELF-LIMITED NEONATAL INFECTION WITH A PNEUMOVIRUS, FOLLOWED BY SENSITISATION TO OVALBUMIN VIA THE RESPIRATORY TRACT AND LOW-LEVEL CHRONIC CHALLENGE WITH AEROSOLISED ANTIGEN, LEADS TO DEVELOPMENT OF AN ASTHMATIC PHENOTYPE. WE ASSESSED EXPRESSION OF MICRORNA BY CELLS IN THE PROXIMAL AIRWAYS, COMPARING CHANGES OVER THE PERIOD OF DISEASE PROGRESSION, AND USED TARGET PREDICTION DATABASES TO IDENTIFY GENES LIKELY TO BE UP- OR DOWNREGULATED AS A CONSEQUENCE OF ALTERED REGULATION OF MICRORNA. IN PARALLEL, WE ASSESSED DNA METHYLATION IN PULMONARY CD4(+) T CELLS. WE FOUND THAT A LIMITED NUMBER OF MICRORNAS EXHIBITED MARKED UP- OR DOWNREGULATION FOLLOWING EARLY-LIFE INFECTION AND SENSITISATION, FOR MANY OF WHICH THE LEVELS OF EXPRESSION WERE FURTHER CHANGED FOLLOWING CHRONIC CHALLENGE WITH THE SENSITIZING ANTIGEN. TARGETS OF THESE MICRORNAS INCLUDED GENES INVOLVED IN IMMUNE OR INFLAMMATORY RESPONSES (E.G. GATA3, KITL) AND IN TISSUE REMODELLING (E.G. IGF1, TGFBR1), AS WELL AS GENES FOR VARIOUS TRANSCRIPTION FACTORS AND SIGNALLING PROTEINS. IN PULMONARY CD4(+) T CELLS, THERE WAS SIGNIFICANT DEMETHYLATION AT PROMOTER SITES FOR INTERLEUKIN-4 AND INTERFERON-GAMMA, THE LATTER INCREASING FOLLOWING CHRONIC CHALLENGE. WE CONCLUDE THAT, IN THIS MODEL, PROGRESSION TO AN ASTHMATIC PHENOTYPE IS LINKED TO EPIGENETIC REGULATION OF GENES ASSOCIATED WITH INFLAMMATION AND STRUCTURAL REMODELLING, AND WITH T-CELL COMMITMENT TO A TH2 IMMUNOLOGICAL RESPONSE. EPIGENETIC CHANGES ASSOCIATED WITH THIS PATTERN OF GENE ACTIVATION MIGHT PLAY A ROLE IN THE DEVELOPMENT OF CHILDHOOD ASTHMA. 2013 20 5548 33 ROLE OF EPIGENETIC REPROGRAMMING OF HOST GENES IN BACTERIAL PATHOGENESIS. THE GENOMES ARE REGULARLY TARGETED BY EPIGENETIC REGULATORY MECHANISMS (DNA METHYLATION, HISTONE MODIFICATIONS, BINDING OF REGULATORY PROTEINS) IN INFECTED CELLS. IN ADDITION, PROTEINS ENCODED BY MICROBIAL GENOMES MAY DISTURB THE ACTION OF A SET OF CELLULAR PROMOTERS BY INTERACTING WITH THE SAME EPI-REGULATORY MACHINERY. THE OUTCOME OF THIS MAY RESULT IN EPIGENETIC DYSREGULATION AND SUBSEQUENT CELLULAR DYSFUNCTIONS THAT MAY MANIFEST IN OR CONTRIBUTE TO THE DEVELOPMENT OF PATHOLOGICAL CHANGES. HOW EPIGENETIC METHYLATION DECORATIONS ON DNA AND HISTONES ARE STARTED AND ESTABLISHED REMAINS LARGELY UNKNOWN. THE INHERITED NATURE OF THESE PROCESSES IN REGULATION OF GENES SUGGESTS THAT THEY COULD PLAY KEY ROLES IN CHRONIC DISEASES ASSOCIATED WITH MICROBIAL PERSISTENCE; THEY MIGHT ALSO EXPLAIN SO-CALLED HIT-AND-RUN PHENOMENA IN INFECTIOUS DISEASE PATHOGENESIS. MICROBES INFECTING MAMMALS MAY CAUSE DISEASES BY CAUSING HYPER-METHYLATION OF KEY CELLULAR PROMOTERS AT CPG DI-NUCLEOTIDES AND MAY INDUCE PATHOLOGICAL CHANGES BY EPIGENETIC REPROGRAMMING OF HOST CELLS THEY ARE INTERACTING WITH ELUCIDATION OF THE EPIGENETIC CONSEQUENCES OF MICROBE-HOST INTERACTIONS MAY HAVE IMPORTANT THERAPEUTIC IMPLICATIONS BECAUSE EPIGENETIC PROCESSES CAN BE REVERTED AND ELIMINATION OF MICROBES INDUCING PATHO-EPIGENETIC CHANGES MAY PREVENT DISEASE DEVELOPMENT. 2013