1 3536 104 IMMUNE CHROMATIN READER SP140 REGULATES MICROBIOTA AND RISK FOR INFLAMMATORY BOWEL DISEASE. INFLAMMATORY BOWEL DISEASE (IBD) IS DRIVEN BY HOST GENETICS AND ENVIRONMENTAL FACTORS, INCLUDING COMMENSAL MICROORGANISMS. SPECKLED PROTEIN 140 (SP140) IS AN IMMUNE-RESTRICTED CHROMATIN "READER" THAT IS ASSOCIATED WITH CROHN'S DISEASE (CD), MULTIPLE SCLEROSIS (MS), AND CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). HOWEVER, THE DISEASE-CAUSING MECHANISMS OF SP140 REMAIN UNDEFINED. HERE, WE IDENTIFY AN IMMUNE-INTRINSIC ROLE FOR SP140 IN REGULATING PHAGOCYTIC DEFENSE RESPONSES TO PREVENT THE EXPANSION OF INFLAMMATORY BACTERIA. MICE HARBORING ALTERED MICROBIOTA DUE TO HEMATOPOIETIC SP140 DEFICIENCY EXHIBITED SEVERE COLITIS THAT WAS TRANSMISSIBLE UPON COHOUSING AND AMELIORATED WITH ANTIBIOTICS. LOSS OF SP140 RESULTS IN BLOOMS OF PROTEOBACTERIA, INCLUDING HELICOBACTER IN SP140(-/-) MICE AND ENTEROBACTERIACEAE IN HUMANS BEARING THE CD-ASSOCIATED SP140 LOSS-OF-FUNCTION VARIANT. PHAGOCYTES FROM PATIENTS WITH THE SP140 LOSS-OF-FUNCTION VARIANT AND SP140(-/-) MICE EXHIBITED ALTERED ANTIMICROBIAL DEFENSE PROGRAMS REQUIRED FOR CONTROL OF PATHOBIONTS. THUS, MUTATIONS WITHIN THIS EPIGENETIC READER MAY CONSTITUTE A PREDISPOSING EVENT IN HUMAN DISEASES PROVOKED BY MICROBIOTA. 2022 2 3732 24 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 3 3760 19 INTEGRATED SINGLE CELL ANALYSIS SHOWS CHRONIC ALCOHOL DRINKING DISRUPTS MONOCYTE DIFFERENTIATION IN THE BONE MARROW. CHRONIC HEAVY ALCOHOL DRINKING (CHD) REWIRES MONOCYTES AND MACROPHAGES TOWARD HEIGHTENED INFLAMMATORY STATES WITH COMPROMISED ANTIMICROBIAL DEFENSES THAT PERSIST AFTER 1-MONTH ABSTINENCE. TO DETERMINE WHETHER THESE CHANGES ARE MEDIATED THROUGH ALTERATIONS IN THE BONE MARROW NICHE, WE PROFILED MONOCYTES AND HEMATOPOIETIC STEM CELL PROGENITORS (HSCPS) FROM CHD RHESUS MACAQUES USING A COMBINATION OF FUNCTIONAL ASSAYS AND SINGLE CELL GENOMICS. CHD RESULTED IN TRANSCRIPTIONAL PROFILES CONSISTENT WITH INCREASED ACTIVATION AND INFLAMMATION WITHIN BONE MARROW RESIDENT MONOCYTES AND MACROPHAGES. FURTHERMORE, CHD RESULTED IN TRANSCRIPTIONAL SIGNATURES ASSOCIATED WITH INCREASED OXIDATIVE AND CELLULAR STRESS IN HSCP. DIFFERENTIATION OF HSCP IN VITRO REVEALED SKEWING TOWARD MONOCYTES EXPRESSING "NEUTROPHIL-LIKE" MARKERS WITH GREATER INFLAMMATORY RESPONSES TO BACTERIAL AGONISTS. FURTHER ANALYSES OF HSCPS SHOWED BROAD EPIGENETIC CHANGES THAT WERE IN LINE WITH EXACERBATED INFLAMMATORY RESPONSES WITHIN MONOCYTES AND THEIR PROGENITORS. IN SUMMARY, CHD ALTERS HSCPS IN THE BONE MARROW LEADING TO THE PRODUCTION OF MONOCYTES POISED TO GENERATE DYSREGULATED HYPER-INFLAMMATORY RESPONSES. 2023 4 6394 28 THE ROLE OF THE HOST-NEUTROPHIL BIOLOGY. NEUTROPHILIC POLYMORPHONUCLEAR LEUKOCYTES (NEUTROPHILS) ARE MYELOID CELLS PACKED WITH LYSOSOMAL GRANULES (HENCE ALSO CALLED GRANULOCYTES) THAT CONTAIN A FORMIDABLE ANTIMICROBIAL ARSENAL. THEY ARE TERMINALLY DIFFERENTIATED CELLS THAT PLAY A CRITICAL ROLE IN ACUTE AND CHRONIC INFLAMMATION, AS WELL AS IN THE RESOLUTION OF INFLAMMATION AND WOUND HEALING. NEUTROPHILS EXPRESS A DENSE ARRAY OF SURFACE RECEPTORS FOR MULTIPLE LIGANDS, RANGING FROM INTEGRINS TO SUPPORT THEIR EGRESS FROM BONE MARROW INTO THE CIRCULATION AND FROM THE CIRCULATION INTO TISSUES, TO CYTOKINE/CHEMOKINE RECEPTORS THAT DRIVE THEIR NAVIGATION TO THE SITE OF INFECTION OR TISSUE DAMAGE AND ALSO PRIME THEM FOR A SECOND STIMULUS, TO PATTERN RECOGNITION RECEPTORS AND IMMUNOGLOBULIN RECEPTORS TO FACILITATE THE DESTRUCTION AND REMOVAL OF INFECTIVE AGENTS OR DEBRIDEMENT OF DAMAGED TISSUES. WHEN AFFERENT NEUTROPHIL SIGNALS ARE PROPORTIONATE AND COORDINATED THEY WILL PHAGOCYTOSE OPSONIZED AND UNOPSONIZED BACTERIA, ACTIVATING THE NICOTINAMIDE ADENINE DINUCLEOTIDE PHOSPHATE OXIDASE (RESPIRATORY BURST) TO GENERATE REACTIVE OXYGEN SPECIES, WHICH AUGMENT THE PROTEOLYTIC DESTRUCTION OF MICROBES SECURED WITHIN THE PHAGOSOME. A HIGHLY ORCHESTRATED PROCESS OF APOPTOSIS FOLLOWS, FORMING MEMBRANE-BOUND SUBSTRUCTURES THAT ARE REMOVED BY MACROPHAGES. NEUTROPHILS ARE CAPABLE OF VARIOUS OTHER FORMS OF PROGRAMMED CELL DEATH, SUCH AS NETOSIS AND PYROPTOTIC CELL DEATH, AS WELL AS NONPROGRAMMED CELL DEATH BY NECROSIS. IN RECENT YEARS, RESEARCH HAS REVEALED THAT NEUTROPHILS ARE CAPABLE OF FAR MORE SUBTLE CELL-CELL INTERACTIONS THAN PREVIOUSLY THOUGHT POSSIBLE. THIS INCLUDES SYNTHESIS OF VARIOUS INFLAMMATORY MEDIATORS AND ALSO MYELOID CELL TRAINING WITHIN BONE MARROW, WHERE EPIGENETIC AND METABOLIC SIGNALS ASSOCIATED WITH RETURNING NEUTROPHILS THAT UNDERGO REVERSE EGRESS FROM TISSUES INTO THE VASCULATURE AND BACK TO BONE MARROW PROGRAM A HYPERREACTIVE SUBSET OF NEUTROPHILS DURING MYELOPOIESIS THAT ARE CAPABLE OF HYPERSENSITIVE REACTIONS TO MICROBIAL AGGRESSORS. THESE CHARACTERISTICS ARE EVIDENT IN VARIOUS NEUTROPHIL SUBSETS/SUBPOPULATIONS, CREATING BROAD HETEROGENEITY IN THE BEHAVIOR AND BIOLOGICAL REPERTOIRE OF THESE SEEMINGLY SCHIZOPHRENIC IMMUNE CELLS. MOREOVER, NEUTROPHILS ARE CRITICAL EFFECTOR CELLS OF ADAPTIVE AND INNATE IMMUNITY, BINDING TO OPSONIZED BACTERIA AND DESTROYING THEM BY EXTRACELLULAR AND INTRACELLULAR METHODS. THE FORMER CREATES SUBSTANTIAL COLLATERAL HOST TISSUE DAMAGE, AS THEY ARE LESS SPECIFIC THAN T-CYTOTOXIC CELL-KILLING MECHANISMS, AND IN CONDITIONS SUCH AS PERI-IMPLANTITIS, WHERE PLASMA CELLS AND NEUTROPHILS DOMINATE THE IMMUNE INFILTRATE, BONE AND TISSUE DESTRUCTION ARE RAPID AND APPEAR RELENTLESS. FINALLY, THE ROLE OF NEUTROPHILS AS CONDUITS FOR PERIODONTAL-SYSTEMIC DISEASE CONNECTIONS AND FOR OXIDATIVE DAMAGE TO ACT AS A CAUSAL LINK BETWEEN THE TWO HAS ONLY RECENTLY BEEN REALIZED. IN THIS CHAPTER, WE ATTEMPT TO EXPAND ON THESE ISSUES, EMPHASIZING THE CONTRIBUTIONS OF EUROPEAN SCIENTISTS THROUGHOUT A DETAILED APPRAISAL OF THE BENEFITS AND SIDE EFFECTS OF NEUTROPHILIC INFLAMMATION AND IMMUNE FUNCTION. 2023 5 6532 24 TRANSCRIPTIONAL REGULATION OF INFLAMMASOMES. INFLAMMASOMES ARE MULTIMOLECULAR COMPLEXES WITH POTENT INFLAMMATORY ACTIVITY. AS SUCH, THEIR ACTIVITY IS TIGHTLY REGULATED AT THE TRANSCRIPTIONAL AND POST-TRANSCRIPTIONAL LEVELS. IN THIS REVIEW, WE PRESENT THE TRANSCRIPTIONAL REGULATION OF INFLAMMASOME GENES FROM SENSORS (E.G., NLRP3) TO SUBSTRATES (E.G., IL-1BETA). LINEAGE-DETERMINING TRANSCRIPTION FACTORS SHAPE INFLAMMASOME RESPONSES IN DIFFERENT CELL TYPES WITH PROFOUND CONSEQUENCES ON THE RESPONSIVENESS TO INFLAMMASOME-ACTIVATING STIMULI. PRO-INFLAMMATORY SIGNALS (STERILE OR MICROBIAL) HAVE A KEY TRANSCRIPTIONAL IMPACT ON INFLAMMASOME GENES, WHICH IS LARGELY MEDIATED BY NF-KAPPAB AND THAT TRANSLATES INTO HIGHER ANTIMICROBIAL IMMUNE RESPONSES. FURTHERMORE, DIVERSE INTRINSIC (E.G., CIRCADIAN CLOCK, METABOLITES) OR EXTRINSIC (E.G., XENOBIOTICS) SIGNALS ARE INTEGRATED BY SIGNAL-DEPENDENT TRANSCRIPTION FACTORS AND CHROMATIN STRUCTURE CHANGES TO MODULATE TRANSCRIPTIONALLY INFLAMMASOME RESPONSES. FINALLY, ANTI-INFLAMMATORY SIGNALS (E.G., IL-10) COUNTERBALANCE INFLAMMASOME GENES INDUCTION TO LIMIT DELETERIOUS INFLAMMATION. TRANSCRIPTIONAL REGULATIONS THUS APPEAR AS THE FIRST LINE OF INFLAMMASOME REGULATION TO RAISE THE DEFENSE LEVEL IN FRONT OF STRESS AND INFECTIONS BUT ALSO TO LIMIT EXCESSIVE OR CHRONIC INFLAMMATION. 2020 6 6376 24 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 7 327 29 ALLERGIC INFLAMMATORY MEMORY IN HUMAN RESPIRATORY EPITHELIAL PROGENITOR CELLS. BARRIER TISSUE DYSFUNCTION IS A FUNDAMENTAL FEATURE OF CHRONIC HUMAN INFLAMMATORY DISEASES(1). SPECIALIZED SUBSETS OF EPITHELIAL CELLS-INCLUDING SECRETORY AND CILIATED CELLS-DIFFERENTIATE FROM BASAL STEM CELLS TO COLLECTIVELY PROTECT THE UPPER AIRWAY(2-4). ALLERGIC INFLAMMATION CAN DEVELOP FROM PERSISTENT ACTIVATION(5) OF TYPE 2 IMMUNITY(6) IN THE UPPER AIRWAY, RESULTING IN CHRONIC RHINOSINUSITIS, WHICH RANGES IN SEVERITY FROM RHINITIS TO SEVERE NASAL POLYPS(7). BASAL CELL HYPERPLASIA IS A HALLMARK OF SEVERE DISEASE(7-9), BUT IT IS NOT KNOWN HOW THESE PROGENITOR CELLS(2,10,11) CONTRIBUTE TO CLINICAL PRESENTATION AND BARRIER TISSUE DYSFUNCTION IN HUMANS. HERE WE PROFILE PRIMARY HUMAN SURGICAL CHRONIC RHINOSINUSITIS SAMPLES (18,036 CELLS, N = 12) THAT SPAN THE DISEASE SPECTRUM USING SEQ-WELL FOR MASSIVELY PARALLEL SINGLE-CELL RNA SEQUENCING(12), REPORT TRANSCRIPTOMES FOR HUMAN RESPIRATORY EPITHELIAL, IMMUNE AND STROMAL CELL TYPES AND SUBSETS FROM A TYPE 2 INFLAMMATORY DISEASE, AND MAP KEY MEDIATORS. BY COMPARISON WITH NASAL SCRAPINGS (18,704 CELLS, N = 9), WE DEFINE SIGNATURES OF CORE, HEALTHY, INFLAMED AND POLYP SECRETORY CELLS. WE REVEAL MARKED DIFFERENCES BETWEEN THE EPITHELIAL COMPARTMENTS OF THE NON-POLYP AND POLYP CELLULAR ECOSYSTEMS, IDENTIFYING AND VALIDATING A GLOBAL REDUCTION IN CELLULAR DIVERSITY OF POLYPS CHARACTERIZED BY BASAL CELL HYPERPLASIA, CONCOMITANT DECREASES IN GLANDULAR CELLS, AND PHENOTYPIC SHIFTS IN SECRETORY CELL ANTIMICROBIAL EXPRESSION. WE DETECT AN ABERRANT BASAL PROGENITOR DIFFERENTIATION TRAJECTORY IN POLYPS, AND PROPOSE CELL-INTRINSIC(13), EPIGENETIC(14,15) AND EXTRINSIC FACTORS(11,16,17) THAT LOCK POLYP BASAL CELLS INTO THIS UNCOMMITTED STATE. FINALLY, WE FUNCTIONALLY DEMONSTRATE THAT EX VIVO CULTURED BASAL CELLS RETAIN INTRINSIC MEMORY OF IL-4/IL-13 EXPOSURE, AND TEST THE POTENTIAL FOR CLINICAL BLOCKADE OF THE IL-4 RECEPTOR ALPHA-SUBUNIT TO MODIFY BASAL AND SECRETORY CELL STATES IN VIVO. OVERALL, WE FIND THAT REDUCED EPITHELIAL DIVERSITY STEMMING FROM FUNCTIONAL SHIFTS IN BASAL CELLS IS A KEY CHARACTERISTIC OF TYPE 2 IMMUNE-MEDIATED BARRIER TISSUE DYSFUNCTION. OUR RESULTS DEMONSTRATE THAT EPITHELIAL STEM CELLS MAY CONTRIBUTE TO THE PERSISTENCE OF HUMAN DISEASE BY SERVING AS REPOSITORIES FOR ALLERGIC MEMORIES. 2018 8 4858 27 ORAL ANTIBIOTIC USE AND CHRONIC DISEASE: LONG-TERM HEALTH IMPACT BEYOND ANTIMICROBIAL RESISTANCE AND CLOSTRIDIOIDES DIFFICILE. WE RECENTLY REPORTED AN INCREASED COLON CANCER RISK ASSOCIATED WITH ORAL ANTIBIOTIC USE IN A LARGE UNITED KINGDOM POPULATION. THIS ASSOCIATION BETWEEN ANTIBIOTIC EXPOSURE AND CANCER RISK ADDS TO A GROWING BODY OF EVIDENCE THAT ANTIBIOTIC USE HAS UNINTENDED OFF-TARGET LONG-TERM HEALTH CONSEQUENCES. THIS ADDENDUM HIGHLIGHTS MAJOR STUDIES LINKING ANTIBIOTIC USE AND CHRONIC DISEASE IN PEDIATRIC AND ADULT POPULATIONS. MICROBIOTA DYSBIOSIS IS THE KEY PROPOSED MECHANISM UNDERLYING ANTIBIOTIC:DISEASE ASSOCIATIONS, RESULTING IN ALTERATIONS IN GENE EXPRESSION, EPIGENETIC MODIFICATION, COLONIZATION BY PATHOGENIC BACTERIA, INSTIGATION OF BIOFILMS, AND IMMUNE REGULATION AND INFLAMMATION. THESE ADVERSE OUTCOMES OF ANTIBIOTIC EXPOSURE UNDERSCORE THE NEED FOR DIAGNOSTIC AND ANTIBIOTIC STEWARDSHIP, AS WELL AS THE URGENCY FOR FURTHER DEVELOPMENT OF NON-ANTIBIOTIC THERAPIES FOR BACTERIAL INFECTIONS. 2020 9 2878 27 FUNCTIONAL T CELLS ARE CAPABLE OF SUPERNUMERARY CELL DIVISION AND LONGEVITY. DIFFERENTIATED SOMATIC MAMMALIAN CELLS PUTATIVELY EXHIBIT SPECIES-SPECIFIC DIVISION LIMITS THAT IMPEDE CANCER BUT MAY CONSTRAIN LIFESPANS(1-3). TO PROVIDE IMMUNITY, TRANSIENTLY STIMULATED CD8(+) T CELLS UNDERGO UNUSUALLY RAPID BURSTS OF NUMEROUS CELL DIVISIONS, AND THEN FORM QUIESCENT LONG-LIVED MEMORY CELLS THAT REMAIN POISED TO REPROLIFERATE FOLLOWING SUBSEQUENT IMMUNOLOGICAL CHALLENGES. HERE WE ADDRESSED WHETHER T CELLS ARE INTRINSICALLY CONSTRAINED BY CHRONOLOGICAL OR CELL-DIVISION LIMITS. WE ACTIVATED MOUSE T CELLS IN VIVO USING ACUTE HETEROLOGOUS PRIME-BOOST-BOOST VACCINATIONS(4), TRANSFERRED EXPANDED CELLS TO NEW MICE, AND THEN REPEATED THIS PROCESS ITERATIVELY. OVER 10 YEARS (GREATLY EXCEEDING THE MOUSE LIFESPAN)(5) AND 51 SUCCESSIVE IMMUNIZATIONS, T CELLS REMAINED COMPETENT TO RESPOND TO VACCINATION. CELLS REQUIRED SUFFICIENT REST BETWEEN STIMULATION EVENTS. DESPITE DEMONSTRATING THE POTENTIAL TO EXPAND THE STARTING POPULATION AT LEAST 10(40)-FOLD, CELLS DID NOT SHOW LOSS OF PROLIFERATION CONTROL AND RESULTS WERE NOT DUE TO CONTAMINATION WITH YOUNG CELLS. PERSISTENT STIMULATION BY CHRONIC INFECTIONS OR CANCER CAN CAUSE T CELL PROLIFERATIVE SENESCENCE, FUNCTIONAL EXHAUSTION AND DEATH(6). WE FOUND THAT ALTHOUGH ITERATIVE ACUTE STIMULATIONS ALSO INDUCED SUSTAINED EXPRESSION AND EPIGENETIC REMODELLING OF COMMON EXHAUSTION MARKERS (INCLUDING PD1, WHICH IS ALSO KNOWN AS PDCD1, AND TOX) IN THE CELLS, THEY COULD STILL PROLIFERATE, EXECUTE ANTIMICROBIAL FUNCTIONS AND FORM QUIESCENT MEMORY CELLS. THESE OBSERVATIONS PROVIDE A MODEL TO BETTER UNDERSTAND MEMORY CELL DIFFERENTIATION, EXHAUSTION, CANCER AND AGEING, AND SHOW THAT FUNCTIONALLY COMPETENT T CELLS CAN RETAIN THE POTENTIAL FOR EXTRAORDINARY POPULATION EXPANSION AND LONGEVITY WELL BEYOND THEIR ORGANISMAL LIFESPAN. 2023 10 4726 12 NOT-SO-OPPOSITE ENDS OF THE SPECTRUM: CD8(+) T CELL DYSFUNCTION ACROSS CHRONIC INFECTION, CANCER AND AUTOIMMUNITY. CD8(+) T CELLS ARE CRITICAL MEDIATORS OF CYTOTOXIC EFFECTOR FUNCTION IN INFECTION, CANCER AND AUTOIMMUNITY. IN CANCER AND CHRONIC VIRAL INFECTION, CD8(+) T CELLS UNDERGO A PROGRESSIVE LOSS OF CYTOKINE PRODUCTION AND CYTOTOXICITY, A STATE TERMED T CELL EXHAUSTION. IN AUTOIMMUNITY, AUTOREACTIVE CD8(+) T CELLS RETAIN THE CAPACITY TO EFFECTIVELY MEDIATE THE DESTRUCTION OF HOST TISSUES. ALTHOUGH THE CLINICAL OUTCOME DIFFERS IN EACH CONTEXT, CD8(+) T CELLS ARE CHRONICALLY EXPOSED TO ANTIGEN IN ALL THREE. THESE CHRONICALLY STIMULATED CD8(+) T CELLS SHARE SOME COMMON PHENOTYPIC FEATURES, AS WELL AS TRANSCRIPTIONAL AND EPIGENETIC PROGRAMMING, ACROSS DISEASE CONTEXTS. A BETTER UNDERSTANDING OF THESE CD8(+) T CELL STATES MAY REVEAL NOVEL STRATEGIES TO AUGMENT CLEARANCE OF CHRONIC VIRAL INFECTION AND CANCER AND TO MITIGATE SELF-REACTIVITY LEADING TO TISSUE DAMAGE IN AUTOIMMUNITY. 2021 11 5429 20 REGULATION OF TYPE I INTERFERON RESPONSES. TYPE I INTERFERONS (IFNS) ACTIVATE INTRACELLULAR ANTIMICROBIAL PROGRAMMES AND INFLUENCE THE DEVELOPMENT OF INNATE AND ADAPTIVE IMMUNE RESPONSES. CANONICAL TYPE I IFN SIGNALLING ACTIVATES THE JANUS KINASE (JAK)-SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION (STAT) PATHWAY, LEADING TO TRANSCRIPTION OF IFN-STIMULATED GENES (ISGS). HOST, PATHOGEN AND ENVIRONMENTAL FACTORS REGULATE THE RESPONSES OF CELLS TO THIS SIGNALLING PATHWAY AND THUS CALIBRATE HOST DEFENCES WHILE LIMITING TISSUE DAMAGE AND PREVENTING AUTOIMMUNITY. HERE, WE SUMMARIZE THE SIGNALLING AND EPIGENETIC MECHANISMS THAT REGULATE TYPE I IFN-INDUCED STAT ACTIVATION AND ISG TRANSCRIPTION AND TRANSLATION. THESE REGULATORY MECHANISMS DETERMINE THE BIOLOGICAL OUTCOMES OF TYPE I IFN RESPONSES AND WHETHER PATHOGENS ARE CLEARED EFFECTIVELY OR CHRONIC INFECTION OR AUTOIMMUNE DISEASE ENSUES. 2014 12 6502 22 TRAINED IMMUNITY: LONG-TERM ADAPTATION IN INNATE IMMUNE RESPONSES. ADAPTIVE IMMUNE RESPONSES ARE CHARACTERIZED BY ANTIGEN SPECIFICITY AND INDUCTION OF LIFELONG IMMUNOLOGIC MEMORY. RECENTLY, IT HAS BEEN REPORTED THAT INNATE IMMUNE CELLS CAN ALSO BUILD IMMUNE MEMORY CHARACTERISTICS-A PROCESS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY DESCRIBES THE PERSISTENT HYPERRESPONSIVE PHENOTYPE THAT INNATE IMMUNE CELLS CAN DEVELOP AFTER BRIEF STIMULATION. PATHOGENIC STIMULI SUCH AS MICROORGANISMS, AND ALSO ENDOGENOUS MOLECULES INCLUDING URIC ACID, OXIDIZED LDL (LOW-DENSITY LIPOPROTEIN), AND CATECHOLAMINES, ARE CAPABLE OF INDUCING MEMORY IN MONOCYTES AND MACROPHAGES. WHILE TRAINED IMMUNITY PROVIDES FAVORABLE CROSS-PROTECTION IN THE CONTEXT OF INFECTIOUS DISEASES, THE HEIGHTENED IMMUNE RESPONSE CAN BE MALADAPTIVE IN DISEASES DRIVEN BY CHRONIC SYSTEMIC INFLAMMATION, SUCH AS ATHEROSCLEROSIS. TRAINED IMMUNITY IS MAINTAINED BY DISTINCT EPIGENETIC AND METABOLIC MECHANISMS AND PERSISTS FOR AT LEAST SEVERAL MONTHS IN VIVO DUE TO REPROGRAMMING OF MYELOID PROGENITOR CELLS. ADDITIONALLY, CERTAIN NONIMMUNE CELLS ARE ALSO FOUND TO EXHIBIT TRAINED IMMUNITY CHARACTERISTICS. THUS, TRAINED IMMUNITY PRESENTS AN EXCITING FRAMEWORK TO DEVELOP NEW APPROACHES TO VACCINATION AND ALSO NOVEL PHARMACOLOGICAL TARGETS IN THE TREATMENT OF INFLAMMATORY DISEASES. 2021 13 5425 28 REGULATION OF MYELOPOIESIS BY THE TRANSCRIPTION FACTOR IRF8. INTERFERON REGULATORY FACTOR-8 (IRF8) IS A TRANSCRIPTION FACTOR EXPRESSED IN HEMATOPOIETIC CELLS, PARTICULARLY IN MONONUCLEAR PHAGOCYTES [MONOCYTES/MACROPHAGES AND DENDRITIC CELLS (DCS)] AND THEIR PROGENITORS. VARIOUS STUDIES HAVE DEMONSTRATED THAT IRF8 IS ESSENTIAL FOR THE DEVELOPMENT OF MONOCYTES, DCS, EOSINOPHILS, AND BASOPHILS. CONVERSELY, IRF8 SUPPRESSES THE GENERATION OF NEUTROPHILS. ACCORDINGLY, IRF8 (-/-) MICE DEVELOP IMMUNODEFICIENCY AND A CHRONIC MYELOID LEUKEMIA (CML)-LIKE DISEASE. MUTATIONS AND LOSS OF EXPRESSION OF THE HUMAN IRF8 GENE ARE ALSO ASSOCIATED WITH IMMUNODEFICIENCY AND CML, RESPECTIVELY. RECENT FINDINGS HAVE BEGUN TO REVEAL THE TRANSCRIPTION FACTOR NETWORK AND EPIGENETIC CHANGES GOVERNED BY IRF8. FOR EXAMPLE, IN MONONUCLEAR PHAGOCYTE PROGENITORS, IRF8 COOPERATES WITH PU.1 TO PROMOTE THE FORMATION OF PROMOTER-DISTAL ENHANCERS TO INDUCE MONOCYTE-RELATED GENES INCLUDING THE CRITICAL DOWNSTREAM TRANSCRIPTION FACTOR GENE KLF4. ON THE OTHER HAND, IRF8 BLOCKS C/EBPALPHA ACTIVITY TO SUPPRESS THE NEUTROPHIL DIFFERENTIATION PROGRAM. INDEED, IRF8 (-/-) MONONUCLEAR PHAGOCYTE PROGENITORS FAIL TO EFFICIENTLY GENERATE MONOCYTES AND DCS AND, INSTEAD, ABERRANTLY GIVE RISE TO NEUTROPHILS. THIS ARTICLE PROVIDES AN OVERVIEW OF RECENT ADVANCES IN OUR UNDERSTANDING OF THE ROLE OF IRF8 IN MYELOPOIESIS AND RELATED DISEASES. 2015 14 1349 27 DETERMINANTS OF INNATE IMMUNITY IN VISCERAL LEISHMANIASIS AND THEIR IMPLICATION IN VACCINE DEVELOPMENT. LEISHMANIASIS IS ENDEMIC TO THE TROPICAL AND SUBTROPICAL REGIONS OF THE WORLD AND IS TRANSMITTED BY THE BITE OF AN INFECTED SAND FLY. THE MULTIFACETED INTERACTIONS BETWEEN LEISHMANIA, THE HOST INNATE IMMUNE CELLS, AND THE ADAPTIVE IMMUNITY DETERMINE THE SEVERITY OF PATHOGENESIS AND DISEASE DEVELOPMENT. LEISHMANIA PARASITES ESTABLISH A CHRONIC INFECTION BY SUBVERSION AND ATTENUATION OF THE MICROBICIDAL FUNCTIONS OF PHAGOCYTIC INNATE IMMUNE CELLS SUCH AS NEUTROPHILS, MACROPHAGES AND DENDRITIC CELLS (DCS). OTHER INNATE CELLS SUCH AS INFLAMMATORY MONOCYTES, MAST CELLS AND NK CELLS, ALSO CONTRIBUTE TO RESISTANCE AND/OR SUSCEPTIBILITY TO LEISHMANIA INFECTION. IN ADDITION TO THE CYTOKINE/CHEMOKINE SIGNALS FROM THE INNATE IMMUNE CELLS, RECENT STUDIES IDENTIFIED THE SUBTLE SHIFTS IN THE METABOLIC PATHWAYS OF THE INNATE CELLS THAT ACTIVATE DISTINCT IMMUNE SIGNAL CASCADES. THE NEXUS BETWEEN METABOLIC PATHWAYS, EPIGENETIC REPROGRAMMING AND THE IMMUNE SIGNALING CASCADES THAT DRIVE THE DIVERGENT INNATE IMMUNE RESPONSES, REMAINS TO BE FULLY UNDERSTOOD IN LEISHMANIA PATHOGENESIS. FURTHER, DEVELOPMENT OF SAFE AND EFFICACIOUS VACCINES AGAINST LEISHMANIASIS REQUIRES A BROADER UNDERSTANDING OF THE EARLY INTERACTIONS BETWEEN THE PARASITES AND INNATE IMMUNE CELLS. IN THIS REVIEW WE FOCUS ON THE CURRENT UNDERSTANDING OF THE SPECIFIC ROLE OF INNATE IMMUNE CELLS, THE METABOLOMIC AND EPIGENETIC REPROGRAMMING AND IMMUNE REGULATION THAT OCCURS DURING VISCERAL LEISHMANIASIS, AND THE STRATEGIES USED BY THE PARASITE TO EVADE AND MODULATE HOST IMMUNITY. WE HIGHLIGHT HOW SUCH PATHWAYS COULD BE EXPLOITED IN THE DEVELOPMENT OF SAFE AND EFFICACIOUS LEISHMANIA VACCINES. 2021 15 1310 22 DEFINING TRAINED IMMUNITY AND ITS ROLE IN HEALTH AND DISEASE. IMMUNE MEMORY IS A DEFINING FEATURE OF THE ACQUIRED IMMUNE SYSTEM, BUT ACTIVATION OF THE INNATE IMMUNE SYSTEM CAN ALSO RESULT IN ENHANCED RESPONSIVENESS TO SUBSEQUENT TRIGGERS. THIS PROCESS HAS BEEN TERMED 'TRAINED IMMUNITY', A DE FACTO INNATE IMMUNE MEMORY. RESEARCH IN THE PAST DECADE HAS POINTED TO THE BROAD BENEFITS OF TRAINED IMMUNITY FOR HOST DEFENCE BUT HAS ALSO SUGGESTED POTENTIALLY DETRIMENTAL OUTCOMES IN IMMUNE-MEDIATED AND CHRONIC INFLAMMATORY DISEASES. HERE WE DEFINE 'TRAINED IMMUNITY' AS A BIOLOGICAL PROCESS AND DISCUSS THE INNATE STIMULI AND THE EPIGENETIC AND METABOLIC REPROGRAMMING EVENTS THAT SHAPE THE INDUCTION OF TRAINED IMMUNITY. 2020 16 6181 22 THE IMMUNE FUNCTIONS OF KERATINOCYTES IN SKIN WOUND HEALING. AS THE MOST DOMINANT CELL TYPE IN THE SKIN, KERATINOCYTES PLAY CRITICAL ROLES IN WOUND REPAIR NOT ONLY AS STRUCTURAL CELLS BUT ALSO EXERTING IMPORTANT IMMUNE FUNCTIONS. THIS REVIEW FOCUSES ON THE COMMUNICATIONS BETWEEN KERATINOCYTES AND IMMUNE CELLS IN WOUND HEALING, WHICH ARE MEDIATED BY VARIOUS CYTOKINES, CHEMOKINES, AND EXTRACELLULAR VESICLES. KERATINOCYTES CAN ALSO DIRECTLY INTERACT WITH T CELLS VIA ANTIGEN PRESENTATION. MOREOVER, KERATINOCYTES PRODUCE ANTIMICROBIAL PEPTIDES THAT CAN DIRECTLY KILL THE INVADING PATHOGENS AND CONTRIBUTE TO WOUND REPAIR IN MANY ASPECTS. WE ALSO REVIEWED THE EPIGENETIC MECHANISMS KNOWN TO REGULATE KERATINOCYTE IMMUNE FUNCTIONS, INCLUDING HISTONE MODIFICATIONS, NON-PROTEIN-CODING RNAS (E.G., MICRORNAS, AND LONG NONCODING RNAS), AND CHROMATIN DYNAMICS. LASTLY, WE SUMMARIZED THE CURRENT EVIDENCE ON THE DYSREGULATED IMMUNE FUNCTIONS OF KERATINOCYTES IN CHRONIC NONHEALING WOUNDS. BASED ON THEIR CRUCIAL IMMUNE FUNCTIONS IN SKIN WOUND HEALING, WE PROPOSE THAT KERATINOCYTES SIGNIFICANTLY CONTRIBUTE TO THE PATHOGENESIS OF CHRONIC WOUND INFLAMMATION. WE HOPE THIS REVIEW WILL TRIGGER AN INTEREST IN INVESTIGATING THE IMMUNE ROLES OF KERATINOCYTES IN CHRONIC WOUND PATHOLOGY, WHICH MAY OPEN UP NEW AVENUES FOR DEVELOPING INNOVATIVE WOUND TREATMENTS. 2020 17 6503 19 TRAINED IMMUNITY: REPROGRAMMING INNATE IMMUNITY IN HEALTH AND DISEASE. TRADITIONALLY, THE INNATE AND ADAPTIVE IMMUNE SYSTEMS ARE DIFFERENTIATED BY THEIR SPECIFICITY AND MEMORY CAPACITY. IN RECENT YEARS, HOWEVER, THIS PARADIGM HAS SHIFTED: CELLS OF THE INNATE IMMUNE SYSTEM APPEAR TO BE ABLE TO GAIN MEMORY CHARACTERISTICS AFTER TRANSIENT STIMULATION, RESULTING IN AN ENHANCED RESPONSE UPON SECONDARY CHALLENGE. THIS PHENOMENON HAS BEEN CALLED TRAINED IMMUNITY. TRAINED IMMUNITY IS CHARACTERIZED BY NONSPECIFIC INCREASED RESPONSIVENESS, MEDIATED VIA EXTENSIVE METABOLIC AND EPIGENETIC REPROGRAMMING. TRAINED IMMUNITY EXPLAINS THE HETEROLOGOUS EFFECTS OF VACCINES, WHICH RESULT IN INCREASED PROTECTION AGAINST SECONDARY INFECTIONS. HOWEVER, IN CHRONIC INFLAMMATORY CONDITIONS, TRAINED IMMUNITY CAN INDUCE MALADAPTIVE EFFECTS AND CONTRIBUTE TO HYPERINFLAMMATION AND PROGRESSION OF CARDIOVASCULAR DISEASE, AUTOINFLAMMATORY SYNDROMES, AND NEUROINFLAMMATION. IN THIS REVIEW WE SUMMARIZE THE CURRENT STATE OF THE FIELD OF TRAINED IMMUNITY, ITS MECHANISMS, AND ITS ROLES IN BOTH HEALTH AND DISEASE. 2021 18 6494 21 TRAINED IMMUNITY AS A NOVEL THERAPEUTIC STRATEGY. RECENT STUDIES HAVE SHOWN THAT UPON CERTAIN VACCINATIONS OR INFECTIONS HUMAN INNATE IMMUNE CELLS CAN UNDERGO EXTENSIVE METABOLIC AND EPIGENETIC REPROGRAMMING, WHICH RESULTS IN ENHANCED IMMUNE RESPONSES UPON HETEROLOGOUS RE-INFECTION, A PROCESS TERMED TRAINED IMMUNITY. TRAINED IMMUNITY HAS ALSO BEEN SHOWN TO BE INAPPROPRIATELY ACTIVATED IN INFLAMMATORY DISEASES. THIS PROVIDES THE POTENTIAL FOR IDENTIFYING NOVEL THERAPEUTIC TARGETS: POTENTIATION OF TRAINED IMMUNITY COULD PROTECT FROM SECONDARY INFECTIONS AND REVERSE IMMUNOTOLERANT STATES, WHILE INHIBITION OF TRAINED IMMUNITY MIGHT REDUCE EXCESSIVE IMMUNE ACTIVATION IN CHRONIC INFLAMMATORY CONDITIONS. BY TARGETING SPECIFIC MECHANISMS OF TRAINED IMMUNITY ON EITHER IMMUNOLOGIC, METABOLIC OR EPIGENETIC LEVEL, NOVEL THERAPEUTIC APPROACHES COULD BE DEVELOPED. 2018 19 771 25 CD8(+) T CELL EXHAUSTION. CD8(+) T CELLS ARE IMPORTANT FOR THE PROTECTIVE IMMUNITY AGAINST INTRACELLULAR PATHOGENS AND TUMOR. IN THE CASE OF CHRONIC INFECTION OR CANCER, CD8(+) T CELLS ARE EXPOSED TO PERSISTENT ANTIGEN AND/OR INFLAMMATORY SIGNALS. THIS EXCESSIVE AMOUNT OF SIGNALS OFTEN LEADS CD8(+) T CELLS TO GRADUAL DETERIORATION OF T CELL FUNCTION, A STATE CALLED "EXHAUSTION." EXHAUSTED T CELLS ARE CHARACTERIZED BY PROGRESSIVE LOSS OF EFFECTOR FUNCTIONS (CYTOKINE PRODUCTION AND KILLING FUNCTION), EXPRESSION OF MULTIPLE INHIBITORY RECEPTORS (SUCH AS PD-1 AND LAG3), DYSREGULATED METABOLISM, POOR MEMORY RECALL RESPONSE, AND HOMEOSTATIC PROLIFERATION. THESE ALTERED FUNCTIONS ARE CLOSELY RELATED WITH ALTERED TRANSCRIPTIONAL PROGRAM AND EPIGENETIC LANDSCAPE THAT CLEARLY DISTINGUISH EXHAUSTED T CELLS FROM NORMAL EFFECTOR AND MEMORY T CELLS. T CELL EXHAUSTION IS OFTEN ASSOCIATED WITH INEFFICIENT CONTROL OF PERSISTING INFECTIONS AND CANCERS, BUT RE-INVIGORATION OF EXHAUSTED T CELLS WITH INHIBITORY RECEPTOR BLOCKADE CAN PROMOTE IMPROVED IMMUNITY AND DISEASE OUTCOME. ACCUMULATING EVIDENCES SUPPORT THE THERAPEUTIC POTENTIAL OF TARGETING EXHAUSTED T CELLS. HOWEVER, EXHAUSTED T CELLS COMPRISE HETEROGENOUS CELL POPULATION WITH DISTINCT RESPONSIVENESS TO INTERVENTION. UNDERSTANDING MOLECULAR MECHANISM OF T CELL EXHAUSTION IS ESSENTIAL TO ESTABLISH RATIONAL IMMUNOTHERAPEUTIC INTERVENTIONS. 2019 20 3735 21 INNATE IMMUNE MEMORY: IMPLICATIONS FOR DEVELOPMENT OF PEDIATRIC IMMUNOMODULATORY AGENTS AND ADJUVANTED VACCINES. UNIQUE FEATURES OF IMMUNITY EARLY IN LIFE INCLUDE A DISTINCT IMMUNE SYSTEM PARTICULARLY RELIANT ON INNATE IMMUNITY, WITH WEAK T HELPER (TH)1-POLARIZING IMMUNE RESPONSES, AND IMPAIRED RESPONSES TO CERTAIN VACCINES LEADING TO A HEIGHTENED SUSCEPTIBILITY TO INFECTION. TO THESE IMPORTANT ASPECTS, WE NOW ADD AN INCREASINGLY APPRECIATED CONCEPT THAT THE INNATE IMMUNE SYSTEM DISPLAYS EPIGENETIC MEMORY OF AN EARLIER INFECTION OR VACCINATION, A PHENOMENON THAT HAS BEEN NAMED "TRAINED IMMUNITY." EXPOSURE OF NEONATAL LEUKOCYTES IN VITRO OR NEONATAL ANIMALS OR HUMANS IN VIVO TO SPECIFIC INNATE IMMUNE STIMULI RESULTS IN AN ALTERED INNATE IMMUNE SET POINT. GIVEN THE PARTICULAR IMPORTANCE OF INNATE IMMUNITY EARLY IN LIFE, TRAINED IMMUNITY TO EARLY LIFE INFECTION AND/OR IMMUNIZATION MAY PLAY AN IMPORTANT ROLE IN MODULATING BOTH ACUTE AND CHRONIC DISEASES. 2014