1 6057 77 THE DARK SIDE OF REGULATORY T CELLS IN PSORIASIS. PSORIASIS IS A HEREDITARY DISEASE ELICITED BY CHRONIC ACTIVATION OF CUTANEOUS T CELLS. DELINEATING THE MECHANISTIC INTERPLAY OF THE CELL SUBSETS INVOLVED IS KEY TO DEVELOPING THE NEXT GENERATION OF EFFECTIVE TREATMENTS. IN THIS ISSUE, BOVENSCHEN ET AL. REPORT THAT REGULATORY T CELLS MAINTAIN A FINE BALANCE BETWEEN THE TRANSCRIPTION FACTORS FOXP3 AND RORGAMMAT. IN PATIENTS WITH PSORIASIS, TREGS READILY TURN INTO IL-17-EXPRESSING CELLS, THUS POTENTIALLY PERPETUATING THE INFLAMMATORY PROCESS THAT CHARACTERIZES THE DISEASE. RESULTS DEMONSTRATING THAT THE HISTONE/PROTEIN DEACETYLATION INHIBITOR TRICHOSTATIN A CAN BLOCK THIS CONVERSION SUGGEST THAT AN EPIGENETIC MODIFICATION MAY UNDERLIE REGULATORY T-CELL PLASTICITY. 2011 2 5476 29 RESTORING T CELL TOLERANCE, EXPLORING THE POTENTIAL OF HISTONE DEACETYLASE INHIBITORS FOR THE TREATMENT OF JUVENILE IDIOPATHIC ARTHRITIS. JUVENILE IDIOPATHIC ARTHRITIS (JIA) IS CHARACTERIZED BY A LOSS OF IMMUNE TOLERANCE. HERE, THE BALANCE BETWEEN THE ACTIVITY OF EFFECTOR T (TEFF) CELLS AND REGULATORY T (TREG) CELLS IS DISTURBED RESULTING IN CHRONIC INFLAMMATION IN THE JOINTS. PRESENTLY, THERAPEUTIC STRATEGIES ARE PREDOMINANTLY AIMED AT SUPPRESSING IMMUNE ACTIVATION AND PRO-INFLAMMATORY EFFECTOR MECHANISMS, IGNORING THE OPPORTUNITY TO ALSO PROMOTE TOLERANCE BY BOOSTING THE REGULATORY SIDE OF THE IMMUNE BALANCE. HISTONE DEACETYLASES (HDACS) CAN DEACETYLATE BOTH HISTONE AND NON-HISTONE PROTEINS AND HAVE BEEN DEMONSTRATED TO MODULATE EPIGENETIC REGULATION AS WELL AS CELLULAR SIGNALING IN VARIOUS CELL TYPES. IMPORTANTLY, HDACS ARE POTENT REGULATORS OF BOTH TEFF CELL AND TREG CELL FUNCTION AND CAN THUS BE REGARDED AS ATTRACTIVE THERAPEUTIC TARGETS IN CHRONIC INFLAMMATORY ARTHRITIS. HDAC INHIBITORS (HDACI) HAVE PROVEN THERAPEUTIC POTENTIAL IN THE CANCER FIELD, AND ARE PRESENTLY BEING EXPLORED FOR THEIR POTENTIAL IN THE TREATMENT OF AUTOIMMUNE DISEASES. SPECIFIC HDACI HAVE ALREADY BEEN DEMONSTRATED TO REDUCE THE SECRETION OF PRO-INFLAMMATORY CYTOKINES BY TEFF CELLS, AND PROMOTE TREG NUMBERS AND SUPPRESSIVE CAPACITY IN VITRO AND IN VIVO. IN THIS REVIEW, WE OUTLINE THE ROLE OF THE DIFFERENT CLASSES OF HDACS IN BOTH TEFF CELL AND TREG CELL FUNCTION. FURTHERMORE, WE WILL REVIEW THE EFFECT OF DIFFERENT HDACI ON T CELL TOLERANCE AND EXPLORE THEIR POTENTIAL AS A THERAPEUTIC STRATEGY FOR THE TREATMENT OF OLIGOARTICULAR AND POLYARTICULAR JIA. 2019 3 3167 26 GROUP 1 METABOTROPIC GLUTAMATE RECEPTOR EXPRESSION DEFINES A T CELL MEMORY POPULATION DURING CHRONIC TOXOPLASMA INFECTION THAT ENHANCES IFN-GAMMA AND PERFORIN PRODUCTION IN THE CNS. WITHIN THE BRAIN, A PRO-INFLAMMATORY RESPONSE IS ESSENTIAL TO PREVENT CLINICAL DISEASE DUE TO TOXOPLASMA GONDII REACTIVATION. INFECTION IN THE IMMUNOCOMPROMISED LEADS TO LETHAL TOXOPLASMIC ENCEPHALITIS WHILE IN THE IMMUNOCOMPETENT, THERE IS PERSISTENT LOW-GRADE INFLAMMATION WHICH IS DEVOID OF CLINICAL SYMPTOMS. THIS SIGNIFIES THAT THERE IS A WELL-BALANCED AND REGULATED INFLAMMATORY RESPONSE TO T. GONDII IN THE BRAIN. T CELLS ARE THE DOMINANT IMMUNE CELLS THAT PREVENT CLINICAL DISEASE, AND THIS IS MEDIATED THROUGH THE SECRETION OF EFFECTOR MOLECULES SUCH AS PERFORINS AND IFN-GAMMA. THE PRESENCE OF COGNATE ANTIGEN, THE EXPRESSION OF SURVIVAL CYTOKINES, AND THE ALTERATION OF THE EPIGENETIC LANDSCAPE DRIVE THE DEVELOPMENT OF MEMORY T CELLS. HOWEVER, SPECIFIC EXTRINSIC SIGNALS THAT PROMOTE THE FORMATION AND MAINTENANCE OF MEMORY T CELLS WITHIN TISSUE ARE POORLY UNDERSTOOD. DURING CHRONIC INFECTION, THERE IS AN INCREASE IN EXTRACELLULAR GLUTAMATE THAT, DUE TO ITS FUNCTION AS AN EXCITATORY NEUROTRANSMITTER, IS NORMALLY TIGHTLY CONTROLLED IN THE CNS. HERE WE DEMONSTRATE THAT CD8(+) T CELLS FROM THE T. GONDII-INFECTED BRAIN PARENCHYMA ARE ENRICHED FOR METABOTROPIC GLUTAMATE RECEPTORS (MGLUR'S). CHARACTERIZATION STUDIES DETERMINED THAT MGLUR(+) EXPRESSION BY CD8(+) T CELLS DEFINES A DISTINCT MEMORY POPULATION AT THE TRANSCRIPTIONAL AND PROTEIN LEVEL. FINALLY, USING RECEPTOR ANTAGONISTS AND AGONISTS WE DEMONSTRATE MGLUR SIGNALING IS REQUIRED FOR OPTIMAL CD8(+) T CELL PRODUCTION OF THE EFFECTOR CYTOKINE IFNGAMMA. THIS WORK SUGGESTS THAT GLUTAMATE IS AN IMPORTANT ENVIRONMENTAL SIGNAL OF INFLAMMATION THAT PROMOTES T CELL FUNCTION. UNDERSTANDING GLUTAMATE'S INFLUENCE ON T CELLS IN THE BRAIN CAN PROVIDE INSIGHTS INTO THE MECHANISMS THAT GOVERN PROTECTIVE IMMUNITY AGAINST CNS-INFILTRATING PATHOGENS AND NEUROINFLAMMATION. 2023 4 5288 18 PROSPECTS FOR EPIGENETIC COMPOUNDS IN THE TREATMENT OF AUTOIMMUNE DISEASE. THERE IS GROWING EVIDENCE FOR A ROLE FOR EPIGENETIC MECHANISMS IN THE DEVELOPMENT OF AUTOIMMUNE DISEASES. IN MOST CASES OFAUTOIMMUNE DISEASE THE PRECISE EPIGENETIC MECHANISM INVOLVED REMAINS TO BE RESOLVED, HOWEVER DNA HYPOMETHYLATION ACCOMPANIED BY HYPOACETYLATION OFHISTONE H3/H4 IS COMMONLY OBSERVED. DUE TO THE REVERSIBLE NATURE OF EPIGENETIC MARKS THEIR MAINTENANCE ENZYMES SUCH AS DNA METHYLTRANSFERASES (DNMTS), HISTONE DEACETYLASES (HDACS) AND HISTONE LYSINE METHYLTRANSFERASES (HKMT) ARE ATTRACTIVE DRUG TARGETS. SMALL MOLECULE INHIBITORS OF HISTONE MODIFICATION AND DNA METHYLATION MAINTENANCE ARE INCREASINGLY BECOMING AVAILABLE AND WILL BE USEFUL CHEMICAL BIOLOGICAL TOOLS TO DISSECT EPIGENETIC MECHANISMS IN THESE DISEASES. HOWEVER, ALTHOUGH EPIGENETIC THERAPIES USED IN CANCER TREATMENT ARE A PROMISING STARTING POINT FOR THE EXPLORATION OF AUTOIMMUNE DISEASE TREATMENT, THERE IS A REQUIREMENT FOR MORE SPECIFIC AND LESS TOXIC AGENTS FOR THESE CHRONIC DISEASES OR FOR USE AS CHEMOPREVENTATIVE AGENTS. 2011 5 5130 21 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 6 2389 30 EPIGENETIC REPOLARIZATION OF T LYMPHOCYTES FROM CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS USING 5-AZA-2'-DEOXYCYTIDINE. T CELL IMMUNE DYSFUNCTION HAS AN IMPORTANT ROLE IN THE PROFOUND IMMUNE SUPPRESSION THAT CHARACTERIZES CHRONIC LYMPHOCYTIC LEUKEMIA (CLL). IMPROPER POLARIZATION OF T CELLS HAS BEEN PROPOSED AS ONE OF THE MECHANISM INVOLVED. MOUNTING DATA IMPLICATES CHROMATIN REGULATION, NAMELY PROMOTER METHYLATION, IN THE PLASTICITY OF NAIVE HUMAN T CELLS. RECENT IN VITRO EVIDENCE INDICATES THAT THIS PLASTICITY MAY BE PHENOTYPICALLY ALTERED BY USING METHYLATION INHIBITORS WHICH ARE APPROVED FOR CLINICAL USE IN CERTAIN TYPES OF CANCER. THESE RESULTS BEG THE QUESTION: CAN THE INEFFECTIVE POLARIZATION OF T LYMPHOCYTES IN THE CONTEXT OF CLL BE EFFECTIVELY MODULATED USING METHYLATION INHIBITORS IN A SUSTAINABLE THERAPEUTIC FASHION? TO ANSWER THIS QUESTION OUR LABORATORY HAS STUDIED THE EFFECTS OF 5-AZA-2'-DEOXYCYTIDINE (5A2) IN HELPER AND CYTOTOXIC T LYMPHOCYTES FROM HEALTHY DONORS AND CLL PATIENTS IN WELL CHARACTERIZED MOLECULAR AND EPIGENETIC SIGNALING PATHWAYS INVOLVED IN EFFECTIVE POLARIZATION. MOREOVER, WE SOUGHT TO INVESTIGATE THE CONSEQUENCES OF METHYLATION INHIBITOR TREATMENT ON LYMPHOCYTE SURVIVAL, ACTIVATION INTENSITY, AND NAIVE CELL POLARIZATION. OUR DATA INDICATES THAT 5A2 TREATMENT CAN DEPOLARIZE TH2 CELLS TO EFFECTIVELY SECRETE INTERFERON GAMMA, SIGNAL VIA T-BET, AND ACHIEVE DEMETHYLATION OF CRITICAL TH1 SPECIFIC PROMOTERS. MOREOVER, WE DEMONSTRATE THAT 5A2 CAN FORCE TH1 POLARIZATION OF NAIVE T CELLS DESPITE A STRONG IL-4 STIMULI AND A LACK OF IL-12. IN CONCLUSION OUR DATA SEEKS TO DEFINE A MODALITY IN WHICH IMPROPER OR INEFFECTIVE T CELL POLARIZATION CAN BE ALTERED BY 5AZA AND COULD BE INCORPORATED IN FUTURE THERAPEUTIC INTERVENTIONS. 2011 7 6226 12 THE LINK BETWEEN EPIGENETICS, PAIN SENSITIVITY AND CHRONIC PAIN. INCREASING EVIDENCE SUGGESTS AN ASSOCIATION BETWEEN GENE EXPRESSION AND CLINICAL PAIN. EPIGENETIC MODIFICATIONS ARE THE MAIN MODULATORS OF GENE EXPRESSION OR PROTEIN TRANSLATION IN RESPONSE TO ENVIRONMENTAL STIMULI AND PATHOPHYSIOLOGICAL CONDITIONS. PRECLINICAL AND CLINICAL STUDIES INDICATE THAT EPIGENETIC MODIFICATIONS COULD ALSO IMPACT THE DEVELOPMENT OF PAIN, THE TRANSITION FROM ACUTE TO CHRONIC PAIN, AND THE MAINTENANCE HEREOF. 2022 8 6496 32 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 9 4164 28 MEDIATORS OF CAPILLARY-TO-VENULE CONVERSION IN THE CHRONIC INFLAMMATORY SKIN DISEASE PSORIASIS. PSORIASIS IS A CHRONIC INFLAMMATORY SKIN DISEASE CHARACTERIZED BY EPIDERMAL HYPERPLASIA AND HYPERKERATOSIS, IMMUNE CELL INFILTRATION AND VASCULAR REMODELING. DESPITE THE EMERGING RECOGNITION OF VASCULAR NORMALIZATION AS A POTENTIAL STRATEGY FOR MANAGING PSORIASIS, AN IN-DEPTH DELINEATION OF THE REMODELED DERMAL VASCULATURE HAS BEEN MISSING. IN THIS STUDY, WE EXPLOITED 5' SINGLE-CELL RNA SEQUENCING TO INVESTIGATE THE TRANSCRIPTOMIC ALTERATIONS IN DIFFERENT SUBPOPULATIONS OF BLOOD VASCULAR AND LYMPHATIC ENDOTHELIAL CELLS DIRECTLY ISOLATED FROM PSORIATIC AND HEALTHY HUMAN SKIN. INDIVIDUAL SUBTYPES OF ENDOTHELIAL CELLS UNDERWENT SPECIFIC MOLECULAR REPATTERNING ASSOCIATED WITH CELL ADHESION AND EXTRACELLULAR MATRIX ORGANIZATION. BLOOD CAPILLARIES, IN PARTICULAR, SHOWED UPREGULATION OF THE MELANOMA CELL ADHESION MOLECULE AS WELL AS ITS BINDING PARTNERS AND ADOPTED POSTCAPILLARY VENULE?LIKE CHARACTERISTICS DURING CHRONIC INFLAMMATION THAT ARE MORE PERMISSIVE TO LEUKOCYTE TRANSMIGRATION. WE ALSO IDENTIFIED PSORIASIS-SPECIFIC INTERACTIONS BETWEEN CIS-REGULATORY ENHANCERS AND PROMOTERS FOR EACH ENDOTHELIAL CELL SUBTYPE, REVEALING THE DYSREGULATED GENE REGULATORY NETWORKS IN PSORIASIS. TOGETHER, OUR RESULTS PROVIDE MORE INSIGHTS INTO THE SPECIFIC TRANSCRIPTIONAL RESPONSES AND EPIGENETIC SIGNATURES OF ENDOTHELIAL CELLS LINING DIFFERENT VESSEL COMPARTMENTS IN CHRONIC SKIN INFLAMMATION. 2022 10 5421 17 REGULATION OF INTERLEUKIN-23 EXPRESSION IN HEALTH AND DISEASE. INTERLEUKIN (IL)-23 PLAYS A CENTRAL ROLE IN THE ORCHESTRATION OF INFLAMMATORY RESPONSES. PRODUCED BY DENDRITIC CELLS AND MACROPHAGES, THIS CYTOKINE PROMOTES THE PROTECTION OF THE HOST AGAINST MUCOSAL PATHOGENS THROUGH THE INDUCTION OF IL-17 AND RELATED CYTOKINES BY LYMPHOID CELLS. PRECLINICAL DISEASE MODELS AND ASSOCIATION STUDIES IN HUMANS HAVE ALSO CLEARLY DEMONSTRATED THE IMPLICATION OF IL-23 SIGNALLING PATHWAY IN INFLAMMATORY DISEASES. INDEED, THIS CYTOKINE IS NOW CONSIDERED AS A MAJOR THERAPEUTIC TARGET IN IMMUNE-BASED PATHOLOGIES SUCH AS PSORIASIS, ANKYLOSING SPONDYLITIS OR CROHN'S DISEASE. FURTHERMORE, IN THE CONTEXT OF INFLAMMATION-RELATED CANCER, IL-23 IS THOUGHT TO CONTRIBUTE TO TUMORIGENESIS AND PROGRESSION TO METASTATIC DISEASE. HEREIN, WE REVIEW OUR CURRENT UNDERSTANDING OF IL-23 REGULATION AT THE TRANSCRIPTIONAL AND POST-TRANSCRIPTIONAL LEVELS. WE DISCUSS THE RELEVANCE OF THESE FINDINGS IN THE CONTEXT OF INFECTION, CHRONIC INFLAMMATION AND CANCER. 2016 11 2446 23 EPIGENETIC STRATEGIES SYNERGIZE WITH PD-L1/PD-1 TARGETED CANCER IMMUNOTHERAPIES TO ENHANCE ANTITUMOR RESPONSES. IMMUNOTHERAPY STRATEGIES TARGETING THE PROGRAMMED CELL DEATH LIGAND 1 (PD-L1)/PROGRAMMED CELL DEATH 1 (PD-1) PATHWAY IN CLINICAL TREATMENTS HAVE ACHIEVED REMARKABLE SUCCESS IN TREATING MULTIPLE TYPES OF CANCER. HOWEVER, OWING TO THE HETEROGENEITY OF TUMORS AND INDIVIDUAL IMMUNE SYSTEMS, PD-L1/PD-1 BLOCKADE STILL SHOWS SLOW RESPONSE RATES IN CONTROLLING MALIGNANCIES IN MANY PATIENTS. ACCUMULATING EVIDENCE HAS SHOWN THAT AN EFFECTIVE RESPONSE TO ANTI-PD-L1/ANTI-PD-1 THERAPY REQUIRES ESTABLISHING AN INTEGRATED IMMUNE CYCLE. DAMAGE IN ANY STEP OF THE IMMUNE CYCLE IS ONE OF THE MOST IMPORTANT CAUSES OF IMMUNOTHERAPY FAILURE. IMPAIRMENTS IN THE IMMUNE CYCLE CAN BE RESTORED BY EPIGENETIC MODIFICATION, INCLUDING REPROGRAMMING THE ENVIRONMENT OF TUMOR-ASSOCIATED IMMUNITY, ELICITING AN IMMUNE RESPONSE BY INCREASING THE PRESENTATION OF TUMOR ANTIGENS, AND BY REGULATING T CELL TRAFFICKING AND REACTIVATION. THUS, A RATIONAL COMBINATION OF PD-L1/PD-1 BLOCKADE AND EPIGENETIC AGENTS MAY OFFER GREAT POTENTIAL TO RETRAIN THE IMMUNE SYSTEM AND TO IMPROVE CLINICAL OUTCOMES OF CHECKPOINT BLOCKADE THERAPY. 2020 12 2461 22 EPIGENETIC THERAPY AS A PUTATIVE MOLECULAR TARGET TO MODULATE B CELL BIOLOGY AND BEHAVIOR IN THE CONTEXT OF IMMUNOLOGICAL DISORDERS. HISTONE DEACETYLASE- (HDAC-) DEPENDENT EPIGENETIC MECHANISMS HAVE BEEN WIDELY EXPLORED IN THE LAST DECADE IN DIFFERENT TYPES OF MALIGNANCIES IN PRECLINICAL STUDIES. THIS EFFORT LED TO THE DISCOVERY AND DEVELOPMENT OF A RANGE OF NEW HDAC INHIBITORS (IHDAC) WITH DIFFERENT CHEMICAL PROPERTIES AND SELECTIVE ABILITIES. IN FACT, HEMATOLOGICAL MALIGNANCIES WERE THE FIRST ONES TO HAVE NEW IHDACS APPROVED FOR CLINICAL USE, SUCH AS VORINOSTAT AND ROMIDEPSIN FOR CUTANEOUS T CELL LYMPHOMA AND PANOBINOSTAT FOR MULTIPLE MYELOMA. BESIDES THESE PROMISING ALREADY APPROVED IHDACS, WE HIGHLIGHT A RANGE OF STUDIES FOCUSING ON THE HDAC-DEPENDENT EPIGENETIC CONTROL OF B CELL DEVELOPMENT, BEHAVIOR, AND/OR FUNCTION. HERE, WE HIGHLIGHT 21 IHDACS WHICH HAVE BEEN STUDIED IN THE LITERATURE IN THE CONTEXT OF B CELL DEVELOPMENT AND/OR DYSFUNCTION MOSTLY FOCUSED ON B CELL LYMPHOMAGENESIS. REGARDLESS, WE HAVE IDENTIFIED 55 CLINICAL TRIALS USING 6 OUT OF 21 IHDACS TO APPROACH THEIR PUTATIVE ROLES ON B CELL MALIGNANCIES; NONE OF THEM FOCUSES ON PERITONEAL B CELL POPULATIONS. SINCE CELLS BELONGING TO THIS PECULIAR BODY COMPARTMENT, NAMED B1 CELLS, MAY CONTRIBUTE TO THE DEVELOPMENT OF AUTOIMMUNE PATHOLOGIES, SUCH AS LUPUS, A BETTER UNDERSTANDING OF THE HDAC-DEPENDENT EPIGENETIC MECHANISMS THAT CONTROL ITS BIOLOGY AND BEHAVIOR MIGHT SHED LIGHT ON IHDAC USE TO MANAGE THESE IMMUNOLOGICAL DYSFUNCTIONS. IN THIS SENSE, IHDACS MIGHT EMERGE AS A PROMISING NEW APPROACH FOR TRANSLATIONAL STUDIES IN THIS FIELD. IN THIS REVIEW, WE DISCUSS A PUTATIVE ROLE OF IHDACS IN THE MODULATION OF PERITONEAL B CELL SUBPOPULATION'S BALANCE AS WELL AS THEIR ROLE AS THERAPEUTIC AGENTS IN THE CONTEXT OF CHRONIC DISEASES MEDIATED BY PERITONEAL B CELLS. 2020 13 6136 26 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 14 6255 22 THE MICROBIOTA AND EPIGENETIC REGULATION OF T HELPER 17/REGULATORY T CELLS: IN SEARCH OF A BALANCED IMMUNE SYSTEM. IMMUNE CELLS NOT ONLY AFFECT TISSUE HOMEOSTASIS AT THE SITE OF INFLAMMATION BUT ALSO EXERT SYSTEMIC EFFECTS CONTRIBUTING TO MULTIPLE CHRONIC CONDITIONS. RECENT EVIDENCE CLEARLY SUPPORTS AN ALTERED T HELPER 17/REGULATORY T CELL (TH17/TREG) BALANCE LEADING TO THE DEVELOPMENT AND PROGRESSION OF INFLAMMATORY DISEASES THAT NOT ONLY AFFECT THE GASTROINTESTINAL TRACT BUT ALSO HAVE WHOLE-BODY MANIFESTATIONS, INCLUDING INSULIN RESISTANCE. EPIGENETIC MECHANISMS ARE AMENABLE TO BOTH ENVIRONMENTAL AND CIRCULATING FACTORS AND CONTRIBUTE TO DETERMINING THE T CELL LANDSCAPE. THE RECENTLY IDENTIFIED PARTICIPATION OF THE GUT MICROBIOTA IN THE REMODELING OF THE EPIGENOME OF IMMUNE CELLS HAS TRIGGERED A PARADIGM SHIFT IN OUR UNDERSTANDING OF THE ETIOLOGY OF VARIOUS INFLAMMATORY DISEASES AND OPENED NEW PATHS TOWARD THERAPEUTIC STRATEGIES. IN THIS REVIEW, WE PROVIDE AN OVERVIEW OF THE CONTRIBUTION OF THE TH17/TREG BALANCE IN THE DEVELOPMENT AND PROGRESSION OF INFLAMMATORY BOWEL DISEASES AND METABOLIC DISEASES. WE DISCUSS THE INVOLVEMENT OF EPIGENETIC MECHANISMS IN THE REGULATION OF T CELL FUNCTION IN THE PARTICULAR CONTEXT OF DYSBIOSIS. FINALLY, WE EXAMINE THE POTENTIAL FOR NUTRITIONAL INTERVENTIONS AFFECTING THE GUT MICROBIOTA TO RESHAPE THE T CELL EPIGENOME AND ADDRESS THE INFLAMMATORY COMPONENT OF VARIOUS DISEASES. 2017 15 2308 21 EPIGENETIC REGULATION OF CHEMOKINE (CC-MOTIF) LIGAND 2 IN INFLAMMATORY DISEASES. APPROPRIATE RESPONSES TO INFLAMMATION ARE CONDUCIVE TO PATHOGEN ELIMINATION AND TISSUE REPAIR, WHILE UNCONTROLLED INFLAMMATORY REACTIONS ARE LIKELY TO RESULT IN THE DAMAGE OF TISSUES. CHEMOKINE (CC-MOTIF) LIGAND 2 (CCL2) IS THE MAIN CHEMOKINE AND ACTIVATOR OF MONOCYTES, MACROPHAGES, AND NEUTROPHILS. CCL2 PLAYED A KEY ROLE IN AMPLIFYING AND ACCELERATING THE INFLAMMATORY CASCADE AND IS CLOSELY RELATED TO CHRONIC NON-CONTROLLABLE INFLAMMATION (CIRRHOSIS, NEUROPATHIC PAIN, INSULIN RESISTANCE, ATHEROSCLEROSIS, DEFORMING ARTHRITIS, ISCHEMIC INJURY, CANCER, ETC.). THE CRUCIAL REGULATORY ROLES OF CCL2 MAY PROVIDE POTENTIAL TARGETS FOR THE TREATMENT OF INFLAMMATORY DISEASES. THEREFORE, WE PRESENTED A REVIEW OF THE REGULATORY MECHANISMS OF CCL2. GENE EXPRESSION IS LARGELY AFFECTED BY THE STATE OF CHROMATIN. DIFFERENT EPIGENETIC MODIFICATIONS, INCLUDING DNA METHYLATION, POST-TRANSLATIONAL MODIFICATION OF HISTONES, HISTONE VARIANTS, ATP-DEPENDENT CHROMATIN REMODELLING, AND NON-CODING RNA, COULD AFFECT THE 'OPEN' OR 'CLOSED' STATE OF DNA, AND THEN SIGNIFICANTLY AFFECT THE EXPRESSION OF TARGET GENES. SINCE MOST EPIGENETIC MODIFICATIONS ARE PROVEN TO BE REVERSIBLE, TARGETING THE EPIGENETIC MECHANISMS OF CCL2 IS EXPECTED TO BE A PROMISING THERAPEUTIC STRATEGY FOR INFLAMMATORY DISEASES. THIS REVIEW FOCUSES ON THE EPIGENETIC REGULATION OF CCL2 IN INFLAMMATORY DISEASES. 2023 16 2533 26 EPIGENETICS IN AUTOIMMUNE CONNECTIVE TISSUE DISEASES. BACKGROUND. AUTOIMMUNE CONNECTIVE TISSUE DISEASES (ACTDS) ENCOMPASS A HETEROGENEOUS GROUP OF CHRONIC IMMUNE-MEDIATED INFLAMMATORY DISORDERS, PRIMARILY AFFECTING CONNECTIVE TISSUES AND CLINICALLY CHARACTERIZED BY VARIABLE MULTISYSTEM MANIFESTATIONS, FREQUENTLY OVERLAPPING. ENVIRONMENTAL FACTORS ARE THOUGHT TO PROMOTE ACTD DEVELOPMENT IN GENETIC PREDISPOSING/ENDOCRINE PERMISSIVE BACKGROUND THROUGH THE INDUCTION OF EPIGENETIC MODIFICATIONS, CONSISTING OF STABLE, HERITABLE, BUT POTENTIALLY REVERSIBLE CHANGES IN GENE EXPRESSION, OCCURRING WITHOUT ALTERATIONS OF THE DNA SEQUENCE. ACTUALLY, EPIGENETIC MECHANISMS (SUCH AS HISTONE MODIFICATIONS, DNA METHYLATION, NUCLEOSOME POSITIONING, AND RNA INTERFERENCE) LINK GENOTYPE UPSTREAM AND PHENOTYPE DOWNSTREAM, AND, IF PERSISTENTLY ABERRANT, MAY CAUSE A VARIETY OF HUMAN DISEASES, INCLUDING ACTDS. WE AIMED TO REVIEW THE RECENT ADVANCES IN THE KNOWLEDGE OF THE ACTD EPIGENETIC ALTERATIONS. METHODS: A DETAILED SEARCH OF THE AVAILABLE LITERATURE WAS PERFORMED IN THE PUBMED (U.S. NATIONAL LIBRARY OF MEDICINE) DATABASE. RESULTS: GROWING EVIDENCE UNDERLINES THE RELEVANT ROLE OF EPIGENETIC DEFECTS IN THE ACTD PATHOGENESIS, AND SPECIFIC EPIGENETIC PATTERNS CAN REPRESENT DISEASE BIOMARKERS. IN PATIENTS WITH RHEUMATOID ARTHRITIS (RA), EPIGENETIC VARIATIONS INTERACT DETERMINING THE TYPICAL "AGGRESSIVE" PHENOTYPE DISPLAYED BY RA SYNOVIAL FIBROBLASTS. EPIGENETIC MODIFICATIONS ARE INVOLVED IN THE PROFIBROTIC PROCESS THAT CHARACTERIZES SYSTEMIC SCLEROSIS. IN SYSTEMIC LUPUS ERYTHEMATOSUS AND SJOGREN'S SYNDROME, COMPLEX EPIGENETIC CHANGES ALTERING GENE EXPRESSION HAVE BEEN DEMONSTRATED. CONCLUSIONS: COMPREHENSIVE STUDIES WILL CONTRIBUTE TO FURTHER DEFINE THE ABERRANT EPIGENETIC MECHANISMS INVOLVED IN THE ACTDS ETIOPATHOGENESIS. MOREOVER, BEING EPIGENETIC CHANGES POTENTIALLY REVERSIBLE, THE IDENTIFICATION OF ACTDS EPIGENETIC BIOMARKERS WILL ALLOW THE DEVELOPMENT OF THERAPEUTIC STRATEGIES ADDRESSED TO TARGET DYSREGULATED GENES AND CORRECT ABERRANT EPIGENOMIC ALTERATIONS. 2014 17 5431 20 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 6906 20 [THE ROLE OF GLYCANS IN CANCER DEVELOPMENT AND PROGRESSION. CLINICAL APPLICATIONS]. CHANGES IN GLYCOSYLATION PATTERN OF CELL SURFACE, BODY FLUIDS AND EXTRACELLULAR MATRIX GLYCOCONJUGATES IS A CHARACTERISTIC FEATURE OF TUMOR CELL MALIGNANCY. THESE CHANGES ARE THE RESULT OF MUTATIONS OF TUMOR-ASSOCIATED GENES AS WELL AS EPIGENETIC CHANGES IN THE TUMOR ENVIRONMENT, INCLUDING NUTRIENT INFLUX, HYPOXIA, CYTOKINE EXPRESSION AND STIMULATION OF CHRONIC INFLAMMATION. THE UNIQUE SET OF CELL SURFACE GLYCOANTIGENS ON NEOPLASTIC CELLS IS RECOGNIZED BY ENDOGENOUS LECTINS LOCATED IN THE EXTRACELLULAR MATRIX, VASCULAR ENDOTHELIUM, ON LEUKOCYTES OR PLATELETS, AND HAS AN IMPACT ON DISRUPTING BASIC CELLULAR PROCESSES, SUCH AS INTERCELLULAR RECOGNITION, CELL-CELL ADHESION OR CELL-ECM INTERACTION. THESE CHANGES HAVE A CRITICAL IMPACT ON THE MIGRATION, INVASIVE AND METASTATIC POTENTIAL OF NEOPLASTIC CELLS AND MODULATE THE IMMUNE RESPONSE. THIS UNIQUE PATTERN OF SUGAR ANTIGENS ON THE CANCER CELLS CAN BE A VAULABLE MARKER TO IDENTIFY THEM, DETERMINE THE STAGE OF THE DISEASE AS WELL AS BE A TARGET OF ANTI-CANCER THERAPY. 2021 19 1902 21 ENHANCED EXPRESSION OF THE NUCLEAR ENVELOPE LAP2 TRANSCRIPTIONAL REPRESSORS IN NORMAL AND MALIGNANT ACTIVATED LYMPHOCYTES. EXTENSIVE RESEARCH IN RECENT YEARS HAS BROADENED THE FUNCTIONS OF NUCLEAR ENVELOPE PROTEINS BEYOND SIMPLY STABILIZING THE NUCLEUS ARCHITECTURE. PARTICULARLY, INTEGRAL NUCLEAR MEMBRANE PROTEINS, SUCH AS THE ALTERNATIVE SPLICED ISOFORMS OF LAMINA-ASSOCIATED POLYPEPTIDE 2 (LAP2), HAVE BEEN SHOWN TO BE IMPORTANT FOR THE INITIATION OF REPLICATION AND REPRESSION OF TRANSCRIPTION. THE LATTER IS REGULATED BY EPIGENETIC CHANGES, INDUCED BY THE BINDING OF LAP2BETA TO HISTONE DEACETYLASE-3 (HDAC3), RESULTING IN HISTONE H4 DEACETYLATION. INVOLVEMENT OF NUCLEAR ENVELOPE PROTEINS IN PATHOLOGICAL PROLIFERATIVE CONDITIONS, MAINLY THOSE INVOLVING ABNORMAL RECRUITMENT AND ACTIVATION OF HDACS, IS STILL UNKNOWN. IN THIS PAPER, WE SHOW THAT VARIOUS NUCLEAR ENVELOPE PROTEINS ARE HIGHLY EXPRESSED IN NORMAL AND MALIGNANT ACTIVATED LYMPHOCYTES. SPECIFICALLY, RAPIDLY REPLICATING CELLS OF VARIOUS HEMATOLOGICAL MALIGNANCIES HIGHLY EXPRESS LAP2BETA, WHILE SLOWLY PROLIFERATING MALIGNANT CELLS OF CHRONIC MALIGNANT HEMATOLOGICAL DISEASES DO NOT. TAKING TOGETHER THE ELEVATED EXPRESSION OF LAP2BETA IN HIGHLY PROLIFERATIVE MALIGNANT CELLS WITH ITS KNOWN ABILITY TO MODIFY HISTONES THROUGH BINDING WITH HDAC3 RAISES THE POSSIBILITY OF ITS ROLE IN HEMATOLOGICAL MALIGNANCIES INVOLVING ABERRANT ACTIVITY OF HDAC3. BASED ON OUR PRESENTED RESULTS, WE BELIEVE THAT THE LAP2-HDAC REGULATORY PATHWAY SHOULD BE STUDIED AS A NEW TARGET FOR RATIONAL THERAPY. 2007 20 1309 25 DEFINING AND TARGETING PATTERNS OF T CELL DYSFUNCTION IN INBORN ERRORS OF IMMUNITY. INBORN ERRORS OF IMMUNITY (IEIS) ARE A GROUP OF MORE THAN 450 MONOGENIC DISORDERS THAT IMPAIR IMMUNE DEVELOPMENT AND FUNCTION. A SUBSET OF IEIS BLEND INCREASED SUSCEPTIBILITY TO INFECTION, AUTOIMMUNITY, AND MALIGNANCY AND ARE KNOWN COLLECTIVELY AS PRIMARY IMMUNE REGULATORY DISORDERS (PIRDS). WHILE MANY ASPECTS OF IMMUNE FUNCTION ARE ALTERED IN PIRDS, ONE KEY IMPACT IS ON T-CELL FUNCTION. BY THEIR NATURE, PIRDS PROVIDE UNIQUE INSIGHTS INTO HUMAN T-CELL SIGNALING; ALTERATIONS IN INDIVIDUAL SIGNALING MOLECULES TUNE DOWNSTREAM SIGNALING PATHWAYS AND EFFECTOR FUNCTION. QUANTIFYING T-CELL DYSFUNCTION IN PIRDS AND THE UNDERLYING CAUSATIVE MECHANISMS IS CRITICAL TO IDENTIFYING EXISTING THERAPIES AND POTENTIAL NOVEL THERAPEUTIC TARGETS TO TREAT OUR RARE PATIENTS AND GAIN DEEPER INSIGHT INTO THE BASIC MECHANISMS OF T-CELL FUNCTION. THOUGH THERE ARE MANY TYPES OF T-CELL DYSFUNCTION, HERE WE WILL FOCUS ON T-CELL EXHAUSTION, A KEY PATHOPHYSIOLOGICAL STATE. EXHAUSTION HAS BEEN DESCRIBED IN BOTH HUMAN AND MOUSE MODELS OF DISEASE, WHERE THE CHRONIC PRESENCE OF ANTIGEN AND INFLAMMATION (E.G., CHRONIC INFECTION OR MALIGNANCY) INDUCES A STATE OF ALTERED IMMUNE PROFILE, TRANSCRIPTIONAL AND EPIGENETIC STATES, AS WELL AS IMPAIRED T-CELL FUNCTION. SINCE A SUBSET OF PIRDS AMPLIFY T-CELL RECEPTOR (TCR) SIGNALING AND/OR INFLAMMATORY CYTOKINE SIGNALING CASCADES, IT IS POSSIBLE THAT THEY COULD INDUCE T-CELL EXHAUSTION BY GENETICALLY MIMICKING CHRONIC INFECTION. HERE, WE REVIEW THE FUNDAMENTALS OF T-CELL EXHAUSTION AND ITS POSSIBLE ROLE IN IEIS IN WHICH GENETIC MUTATIONS MIMIC PROLONGED OR AMPLIFIED T-CELL RECEPTOR AND/OR CYTOKINE SIGNALING. GIVEN THE POTENTIAL INSIGHT FROM THE MANY FORMS OF PIRDS IN UNDERSTANDING T-CELL FUNCTION AND THE CHALLENGES IN OBTAINING PRIMARY CELLS FROM THESE RARE DISORDERS, WE ALSO DISCUSS ADVANCES IN CRISPR-CAS9 GENOME-EDITING TECHNOLOGIES AND POTENTIAL APPLICATIONS TO EDIT HEALTHY DONOR T CELLS THAT COULD FACILITATE FURTHER STUDY OF MECHANISMS OF IMMUNE DYSFUNCTIONS IN PIRDS. EDITING T CELLS TO MATCH PIRD PATIENT GENETIC VARIANTS WILL ALLOW INVESTIGATIONS INTO THE MECHANISMS UNDERPINNING STATES OF DYSREGULATED T-CELL FUNCTION, INCLUDING T-CELL EXHAUSTION. 2022