1 6001 140 THE ACUTE KIDNEY INJURY TO CHRONIC KIDNEY DISEASE TRANSITION: A POTENTIAL OPPORTUNITY TO IMPROVE CARE IN ACUTE KIDNEY INJURY. RECENT CONTROLLED TRIALS, EPIDEMIOLOGICAL ANALYSES AND BASIC RESEARCH STUDIES OFFER A COMPREHENSIVE VIEW OF THE SHORT AND LONG-TERM CLINICAL REPERCUSSION OF DE NOVO ACUTE KIDNEY INJURY OR AKI. WHILE MOST POST-AKI PATIENTS RECOVER THEIR BASELINE RENAL FUNCTION, A SIGNIFICANT NUMBER, APPROXIMATELY ~20% OF THOSE AFFECTED, WILL GO ON TO DEVELOP LONG TERM ILLNESS CHARACTERIZED BY AN INCREASE IN LATE STAGE CKD, CARDIOVASCULAR COMPLICATIONS, AND INCREASED DEATH RATES. WHEN AKI OCCURS IN HOSPITALIZED PATIENTS, SELECTED DEMOGRAPHIC AND LABORATORY RESULTS CAN BE INCORPORATED INTO RISK CALCULATORS THAT IDENTIFY THOSE AT HIGHER RISK FOR LONG-TERM COMPLICATIONS. THIS REVIEW TOUCHES ON SOME OF THE SALIENT EPIDEMIOLOGICAL STUDIES OF THE AKI TO CKD TRANSITION. IT ALSO FOCUSES ON CERTAIN RECENT ADVANCEMENTS IN OUR UNDERSTANDING OF THE BIOLOGICAL AND FUNCTIONAL IMPACT OF AKI ON THE RENAL TUBULE REPAIR MECHANISM, AS WELL AS THE IMPORTANT ROLE THAT GENETIC, EPIGENETIC, BIOCHEMICAL AND INFLAMMATORY EVENTS, SEEMINGLY BENEFICIAL TO THE RE-ESTABLISHMENT OF NORMAL RENAL FUNCTION, CAN BE OFFSET BY MEDIATORS OF PROGRESSIVE FIBROSIS AND IRREVERSIBLE STRUCTURAL CHANGES. CHARACTERIZATION OF BASIC PROCESSES THAT MEDIATE THE AKI TO CKD TRANSITION REVEALS PROMISING PHARMACOLOGICAL AND BIOLOGICAL AGENTS THAT HOPEFULLY WILL ONE DAY BE USED IN THE EARLY STAGES OF AKI TO PREVENT ITS DEADLY CONSEQUENCES. 2016 2 221 42 ACUTE KIDNEY INJURY TO CHRONIC KIDNEY DISEASE TRANSITION. BACKGROUND: ACUTE KIDNEY INJURY (AKI), EVEN IF FOLLOWED BY RENAL RECOVERY, IS A RISK FACTOR FOR THE FUTURE DEVELOPMENT OF CHRONIC KIDNEY DISEASE (CKD) AND END-STAGE RENAL DISEASE (ESRD). IN THE PREVIOUS YEARS, NOVEL INSIGHTS IN THE PATHOPHYSIOLOGY OF CKD PROGRESSION SUGGESTED A CAUSAL LINK BETWEEN AKI AND CKD DUE TO A MALADAPTIVE REPAIR AFTER SEVERE AND REPEATED INJURY. SUMMARY: SEVERAL PATHOLOGICAL MECHANISMS HAVE BEEN PROPOSED TO CONTRIBUTE TO THE PROGRESSION OF AKI AND TRANSITION TO CKD/ESRD INCLUDING HYPOXIA AND MICROVASCULAR RAREFACTION, ALTERATIONS OF RENAL RESIDENT CELL PHENOTYPES AND FUNCTIONS, CELL CYCLE ARREST IN THE G2/M PHASE, PERSISTENT CHRONIC INFLAMMATION, AND DEVELOPMENT OF INTERSTITIAL FIBROSIS, MITOCHONDRIAL FRAGMENTATION, EPIGENETIC CHANGES, ACTIVATION OF RENIN-ANGIOTENSIN SYSTEM (RAS), CELL AND TISSUE SENESCENCE. FURTHERMORE, SEVERAL CLINICAL FACTORS HAVE BEEN IDENTIFIED SUCH AS SEVERITY OF AKI, AGE, AND COMORBIDITIES. THE IDENTIFICATION OF AKI-TO-CKD BIOMARKERS COULD IMPROVE THE EARLY IDENTIFICATION OF AKI PATIENTS WITH HIGHER RISK FOR CKD PROGRESSION. HOWEVER, ALTHOUGH OUR UNDERSTANDING IN THE PATHOPHYSIOLOGY OF AKI-TO-CKD TRANSITION IS SIGNIFICANTLY IMPROVED, NO NOVEL INTERVENTION HAS BEEN VALIDATED. POTENTIAL THERAPEUTIC APPROACHES TO TREAT AKI AND BLOCK THE TRANSITION TO CKD/ESRD HAVE BEEN RECENTLY REPORTED, BUT THEY NEED FURTHER VALIDATIONS. KEY MESSAGES: MALADAPTIVE REPAIR AFTER AKI IS STRONGLY ASSOCIATED TO THE DEVELOPMENT OF CKD AND LONG-TERM CONSEQUENCES. THE PROMPT IDENTIFICATION OF PATIENTS AT HIGHER RISK FOR LATE CKD PROGRESSION AND THE DEVELOPMENT OF NEW THERAPEUTIC INTERVENTIONS REMAIN CRITICAL RESEARCH GOALS. 2018 3 2193 45 EPIGENETIC MODIFICATION DRIVES ACUTE KIDNEY INJURY-TO-CHRONIC KIDNEY DISEASE PROGRESSION. ACUTE KIDNEY INJURY (AKI) IS A COMMON CLINICAL CRITICAL DISEASE. DUE TO ITS HIGH MORBIDITY, INCREASING RISK OF COMPLICATIONS, HIGH MORTALITY RATE, AND HIGH MEDICAL COSTS, IT HAS BECOME A GLOBAL CONCERN FOR HUMAN HEALTH PROBLEMS. INITIALLY, RESEARCHERS BELIEVED THAT KIDNEYS HAVE A STRONG ABILITY TO REGENERATE AND REPAIR, BUT STUDIES OVER THE PAST 20 YEARS HAVE FOUND THAT KIDNEYS DAMAGED BY AKI ARE OFTEN INCOMPLETE OR EVEN UNABLE TO REPAIR. EVEN WHEN SERUM CREATININE RETURNS TO BASELINE LEVELS, RENAL STRUCTURAL DAMAGE PERSISTS FOR A LONG TIME, LEADING TO THE DEVELOPMENT OF CHRONIC KIDNEY DISEASE (CKD). THE MECHANISM OF AKI-TO-CKD TRANSITION HAS NOT BEEN FULLY ELUCIDATED. AS AN IMPORTANT REGULATOR OF GENE EXPRESSION, EPIGENETIC MODIFICATIONS, SUCH AS HISTONE MODIFICATION, DNA METHYLATION, AND NONCODING RNAS, MAY PLAY AN IMPORTANT ROLE IN THIS PROCESS. ALTERATIONS IN EPIGENETIC MODIFICATION ARE INDUCED BY HYPOXIA, THUS PROMOTING THE EXPRESSION OF INFLAMMATORY FACTOR-RELATED GENES AND COLLAGEN SECRETION. THIS REVIEW ELABORATED THE ROLE OF EPIGENETIC MODIFICATIONS IN AKI-TO-CKD PROGRESSION, THE DIAGNOSTIC VALUE OF EPIGENETIC MODIFICATIONS BIOMARKERS IN AKI CHRONIC OUTCOME, AND THE POTENTIAL ROLE OF TARGETING EPIGENETIC MODIFICATIONS IN THE PREVENTION AND TREATMENT OF AKI TO CKD, IN ORDER TO PROVIDE IDEAS FOR THE SUBSEQUENT ESTABLISHMENT OF TARGETED THERAPEUTIC STRATEGIES TO PREVENT THE PROGRESSION OF RENAL TUBULAR-INTERSTITIAL FIBROSIS. 2021 4 1977 24 EPIGENETIC ALTERATIONS IN ACUTE KIDNEY INJURY. ACUTE KIDNEY INJURY (AKI) IS A RISK FACTOR FOR CHRONIC KIDNEY DISEASE AND DEATH. DESPITE PROGRESS MADE IN UNDERSTANDING THE CELLULAR AND MOLECULAR BASIS OF AKI PATHOGENESIS THERE HAS BEEN NO IMPROVEMENT IN THE HIGH MORTALITY RATE FROM THIS DISEASE IN DECADES. EPIGENETICS IS ONE OF THE MOST INTENSIVELY STUDIED FIELDS OF BIOLOGY TODAY AND REPRESENTS A NEW PARADIGM FOR UNDERSTANDING THE PATHOPHYSIOLOGY OF DISEASE. ALTHOUGH EPIGENETICS OF AKI IS A NASCENT FIELD, THE AVAILABLE INFORMATION ALREADY IS PROVIDING COMPELLING EVIDENCE THAT CHROMATIN BIOLOGY PLAYS A CRITICAL ROLE IN THIS DISEASE. IN THIS ARTICLE WE EXPLORE WHAT IS KNOWN ABOUT THE CONTRIBUTION OF EPIGENETIC MECHANISMS TO THE PATHOPHYSIOLOGY OF AKI AND HOW THIS KNOWLEDGE ALREADY IS GUIDING THE DEVELOPMENT OF NEW DIAGNOSTIC TOOLS AND EPIGENETIC THERAPIES. 2013 5 931 34 CHRONIC KIDNEY DISEASE IN CHILDREN AND THE ROLE OF EPIGENETICS: FUTURE THERAPEUTIC TRAJECTORIES. GLOBAL DIFFERENCES IN THE OBSERVED CAUSES OF CHRONIC KIDNEY DISEASE (CKD) IN CHILDREN ARE WELL DOCUMENTED AND ARE ATTRIBUTED TO DISSIMILARITIES IN CLIME, RACE, HEREDITARY, AND ANCESTRY. THUS, FAMILIAL CLUSTERING AND DISPARITIES IN CKD PREVALENCE RATES ACROSS ETHNIC AND RACIAL GROUPS INDICATE THAT THE PROGRESSION OF RENAL DISEASE HAS A STRONG GENETIC COMPONENT. MAMMALIAN STUDIES HAVE DEMONSTRATED A FEASIBLE NEXUS BETWEEN NUTRITION AND NON-GENETIC EXPOSURE (AROUND THE TIME OF CONCEPTION AND IN EPIGENETIC CHANGES) IN THE EXPRESSION OF MAJOR GENES IDENTIFIED IN RENAL ORGANOGENESIS. THE MAJOR CONSEQUENCE IS A REDUCTION IN THE NUMBER OF NEPHRONS, WITH SUBSEQUENT PREDISPOSITION TO HYPERTENSION AND CKD. IDENTIFYING THESE EPIGENETIC CHANGES IS CRUCIAL (DUE TO THEIR POTENTIALLY REVERSIBLE NATURE), AS THEY MAY SERVE AS FUTURE THERAPEUTIC TARGETS TO PREVENT KIDNEY FIBROSIS AND CKD. DESPITE PROGRESS IN THE FIELD OF EPIGENETICS IN ONCOLOGY, RESEARCH IN OTHER SUBSPECIALTIES OF MEDICINE IS LARGELY EXPERIMENTAL WITH FEW EXISTING STUDIES REGARDING THE CLINICAL IMPLICATION OF EPIGENETICS IN RENAL DISEASE. THERAPEUTIC TRAJECTORIES FOR CKD IN CHILDREN BASED ON THE INFLUENCE OF EPIGENETICS MAY EVENTUALLY REVOLUTIONIZE THE MANAGEMENT OF THIS DISEASE. THE AIM OF THE CURRENT NARRATIVE REVIEW IS TO APPRAISE THE ROLE OF EPIGENETICS IN CKD, AND HIGHLIGHT THE POTENTIAL FUTURE THERAPEUTIC PATHWAYS. 2016 6 6299 44 THE PROXIMAL TUBULE IS THE PRIMARY TARGET OF INJURY AND PROGRESSION OF KIDNEY DISEASE: ROLE OF THE GLOMERULOTUBULAR JUNCTION. THERE IS AN ALARMING GLOBAL INCREASE IN THE INCIDENCE OF END-STAGE KIDNEY DISEASE, FOR WHICH EARLY BIOMARKERS AND EFFECTIVE TREATMENT OPTIONS ARE LACKING. LARGELY BASED ON THE HISTOLOGY OF THE END-STAGE KIDNEY AND ON THE MODEL OF UNILATERAL URETERAL OBSTRUCTION, CURRENT INVESTIGATION IS FOCUSED ON THE PATHOGENESIS OF RENAL INTERSTITIAL FIBROSIS AS A CENTRAL MECHANISM IN THE PROGRESSION OF CHRONIC KIDNEY DISEASE (CKD). IT IS NOW RECOGNIZED THAT CUMULATIVE EPISODES OF ACUTE KIDNEY INJURY (AKI) CAN LEAD TO CKD, AND, CONVERSELY, CKD IS A RISK FACTOR FOR AKI. BASED ON RECENT AND HISTORIC STUDIES, THIS REVIEW SHIFTS ATTENTION FROM THE GLOMERULUS AND INTERSTITIUM TO THE PROXIMAL TUBULE AS THE PRIMARY SENSOR AND EFFECTOR IN THE PROGRESSION OF CKD AS WELL AS AKI. PACKED WITH MITOCHONDRIA AND DEPENDENT ON OXIDATIVE PHOSPHORYLATION, THE PROXIMAL TUBULE IS PARTICULARLY VULNERABLE TO INJURY (OBSTRUCTIVE, ISCHEMIC, HYPOXIC, OXIDATIVE, METABOLIC), RESULTING IN CELL DEATH AND ULTIMATELY IN THE FORMATION OF ATUBULAR GLOMERULI. ANIMAL MODELS OF HUMAN GLOMERULAR AND TUBULAR DISORDERS HAVE PROVIDED EVIDENCE FOR A BROAD REPERTOIRE OF MORPHOLOGICAL AND FUNCTIONAL RESPONSES OF THE PROXIMAL TUBULE, REVEALING PROCESSES OF DEGENERATION AND REPAIR THAT MAY LEAD TO NEW THERAPEUTIC STRATEGIES. MOST PROMISING ARE STUDIES THAT ENCOMPASS THE ENTIRE LIFE CYCLE FROM FETUS TO SENESCENCE, RECOGNIZING EPIGENETIC FACTORS. THE APPLICATION OF TECHNIQUES IN MOLECULAR CHARACTERIZATION OF TUBULE SEGMENTS AND THE DEVELOPMENT OF HUMAN KIDNEY ORGANOIDS MAY PROVIDE NEW INSIGHTS INTO THE MAMMALIAN KIDNEY SUBJECTED TO STRESS OR INJURY, LEADING TO BIOMARKERS OF EARLY CKD AND NEW THERAPIES. 2016 7 5258 36 PROGRESSION OF TUBULOINTERSTITIAL FIBROSIS AND THE CHRONIC KIDNEY DISEASE PHENOTYPE - ROLE OF RISK FACTORS AND EPIGENETICS. ALTHOUGH THE KIDNEY HAS CAPACITY TO REPAIR AFTER MILD INJURY, ONGOING OR SEVERE DAMAGE RESULTS IN SCARRING (FIBROSIS) AND AN ASSOCIATED PROGRESSIVE LOSS OF KIDNEY FUNCTION. HOWEVER, DESPITE ITS UNIVERSAL SIGNIFICANCE, EVIDENCE HIGHLIGHTS A POPULATION BASED HETEROGENEITY IN THE TRAJECTORY OF CHRONIC KIDNEY DISEASE (CKD) IN THESE PATIENTS. TO EXPLAIN THE HETEROGENEITY OF THE CKD PHENOTYPE REQUIRES AN UNDERSTANDING OF THE RELEVANT RISK FACTORS FOR FIBROSIS. THESE FACTORS INCLUDE BOTH THE EXTRINSIC NATURE OF INJURY, AND INTRINSIC FACTORS SUCH AS AGE, GENDER, GENETICS, AND PERPETUAL ACTIVATION OF FIBROBLASTS THROUGH PRIMING. IN MANY CASES AN ADDITIONAL LEVEL OF REGULATION IS PROVIDED BY EPIGENETIC MECHANISMS WHICH INTEGRATE THE VARIOUS PRO-FIBROTIC AND ANTI-FIBROTIC TRIGGERS IN FIBROGENESIS. IN THIS REVIEW WE THEREFORE EXAMINE THE VARIOUS MOLECULAR AND STRUCTURAL CHANGES OF FIBROSIS, AND HOW THEY ARE INFLUENCED BY EXTRINSIC AND INTRINSIC FACTORS. OUR AIM IS TO PROVIDE A UNIFYING HYPOTHESIS TO HELP EXPLAIN THE TRANSITION FROM ACUTE TO CKD. 2017 8 1880 46 EMERGING STRATEGIES TO DISRUPT THE CENTRAL TGF-BETA AXIS IN KIDNEY FIBROSIS. CHRONIC KIDNEY DISEASE (CKD) AFFECTS MORE THAN 20 MILLION PEOPLE IN THE UNITED STATES AND THE GLOBAL BURDEN OF THIS DISORDER IS INCREASING. MANY AFFECTED INDIVIDUALS WILL PROGRESS TO END STAGE KIDNEY DISEASE NECESSITATING DIALYSIS OR TRANSPLANTATION. CKD IS ALSO A MAJOR INDEPENDENT CONTRIBUTOR TO THE RISK OF CARDIOVASCULAR MORBIDITY AND MORTALITY. TUBULOINTERSTITIAL FIBROSIS IS A FINAL COMMON PATHWAY FOR MOST CAUSES OF PROGRESSIVE CKD. CURRENTLY, THERE ARE NO CLINICALLY AVAILABLE THERAPIES TARGETING FIBROSIS THAT CAN SLOW THE DECLINE IN KIDNEY FUNCTION. ALTHOUGH IT HAS LONG BEEN KNOWN THAT TGF-BETA SIGNALING IS A CRITICAL MEDIATOR OF KIDNEY FIBROSIS, TRANSLATING THIS KNOWLEDGE TO THE CLINIC HAS BEEN CHALLENGING. IN THIS REVIEW, WE HIGHLIGHT SOME RECENT INSIGHTS INTO THE MECHANISMS OF TGF-BETA SIGNALING THAT TARGET ACTIVATION OF THIS CYTOKINE AT THE SITE OF INJURY OR SELECTIVELY INHIBIT PRO-FIBROTIC GENE EXPRESSION. MOLECULES DIRECTED AT THESE TARGETS HOLD THE PROMISE OF ATTAINING THERAPEUTIC EFFICACY WHILE LIMITING TOXICITY SEEN WITH GLOBAL INHIBITION OF TGF-BETA. KIDNEY INJURY HAS PROFOUND EPIGENETIC EFFECTS LEADING TO ALTERED EXPRESSION OF MORE THAN A THOUSAND GENES. WE DISCUSS HOW DRUGS TARGETING EPIGENETIC MODIFICATIONS, SOME OF WHICH ARE IN USE FOR CANCER THERAPY, HAVE THE POTENTIAL TO REPROGRAM GENE REGULATORY NETWORKS TO FAVOR ADAPTIVE REPAIR AND PREVENT FIBROSIS. THE LACK OF RELIABLE BIOMARKERS OF KIDNEY FIBROSIS IS A MAJOR LIMITATION IN DESIGNING CLINICAL TRIALS FOR TESTING CKD TREATMENTS. WE CONCLUDE BY REVIEWING RECENT ADVANCES IN FIBROSIS BIOMARKER DEVELOPMENT. 2019 9 5660 29 SEX-SPECIFIC EPIGENETIC PROGRAMMING IN RENAL FIBROSIS AND INFLAMMATION. THE GROWING PREVALENCE OF HYPERTENSION, HEART DISEASE, DIABETES, AND OBESITY ALONG WITH AN AGING POPULATION, IS LEADING TO HIGHER INCIDENCE OF RENAL DISEASES IN THE SOCIETY. CHRONIC KIDNEY DISEASE (CKD) IS CHARACTERIZED MAINLY BY PERSISTENT INFLAMMATION, FIBROSIS, AND GRADUAL LOSS OF RENAL FUNCTION LEADING TO RENAL FAILURE. SEX IS A KNOWN CONTRIBUTOR TO THE DIFFERENCES IN INCIDENCE AND PROGRESSION OF CKD. EPIGENETIC PROGRAMMING IS AN ESSENTIAL REGULATOR OF RENAL PHYSIOLOGY AND IS CRITICALLY INVOLVED IN THE PATHOPHYSIOLOGY OF RENAL INJURY AND FIBROSIS. EPIGENETIC SIGNALING INTEGRATES INTRINSIC AND EXTRINSIC SIGNALS ONTO THE GENOME, AND VARIOUS ENVIRONMENTAL AND HORMONAL STIMULI, INCLUDING SEX HORMONES, WHICH REGULATE GENE EXPRESSION AND DOWNSTREAM CELLULAR RESPONSES. THE MOST EXTENSIVELY STUDIED EPIGENETIC ALTERATIONS THAT PLAY A CRITICAL ROLE IN RENAL DAMAGE INCLUDE HISTONE MODIFICATIONS AND DNA METHYLATION. NOTABLY, THESE EPIGENETIC ALTERATIONS ARE REVERSIBLE, MAKING THEM CANDIDATES FOR POTENTIAL THERAPEUTIC TARGETS FOR THE TREATMENT OF RENAL DISEASES. HERE, WE WILL SUMMARIZE THE CURRENT KNOWLEDGE ON SEX-DIFFERENCES IN EPIGENETIC MODULATION OF RENAL FIBROSIS AND INFLAMMATION AND HIGHLIGHT SOME POSSIBLE EPIGENETIC THERAPEUTIC STRATEGIES FOR CKD TREATMENT. 2023 10 2154 42 EPIGENETIC MECHANISMS AND KIDNEY DISEASES. IN RECENT YEARS, MOLECULAR RESEARCH HAS BROUGHT TO LIGHT A SERIES OF MECHANISMS INVOLVED IN THE REGULATION OF GENE FUNCTION WITHOUT ALTERING THE DNA SEQUENCE. THESE MECHANISMS ARE DESCRIBED WITH THE TERM "EPIGENETICS" AND INCLUDE MODIFICATIONS IN THE STRUCTURE OF THE HUMAN GENOME, LEADING TO HERITABLE AND POTENTIALLY REVERSIBLE CHANGES IN GENE EXPRESSION. THERE IS NOW INCREASING EVIDENCE SUGGESTING THAT SEVERAL CHARACTERISTIC FEATURES OF CHRONIC KIDNEY DISEASE SUCH AS HYPERHOMOCYSTEINEMIA, SUBCLINICAL INFLAMMATION, INCREASED OXIDATIVE STRESS AND OTHERS MAY AFFECT THE HUMAN EPIGENOME. IN ADDITION, ANIMAL STUDIES HAVE SUGGESTED A POSSIBLE LINK BETWEEN NUTRITION AND ENVIRONMENTAL EXPOSURE DURING THE PERICONCEPTIONAL PERIOD AND EPIGENETIC CHANGES IN THE EXPRESSION OF MAJOR GENES IMPLICATED IN KIDNEY ORGANOGENESIS; THESE CHANGES RESULT IN A DIMINISHED NUMBER OF NEPHRONS IN THE DEVELOPING KIDNEY, WHICH PREDISPOSES TO AN INCREASED RISK FOR HYPERTENSION AND CHRONIC KIDNEY DISEASE IN FUTURE LIFE. THE UNDERSTANDING OF THE ROLE OF EPIGENETIC PHENOMENA IN THE PATHOGENESIS OF CHRONIC KIDNEY DISEASE OPENS NEW AVENUES FOR FUTURE THERAPEUTIC STRATEGIES, THROUGH THE DEVELOPMENT OF PHARMACEUTICAL AGENTS THAT TARGET DIRECTLY WITH THE CHANGES IN THE HUMAN EPIGENOME. SUCH EPIGENETIC DRUGS ARE ALREADY IN CLINICAL USE FOR THE TREATMENT OF CANCER AS WELL AS UNDER INVESTIGATION FOR THE USE IN OTHER DISEASES. THIS REVIEW WILL SUMMARIZE THE EXISTING DATA ON THE LINK BETWEEN EPIGENETIC MECHANISMS AND CHRONIC UREMIC MILIEU, AS WELL AS THE PROMISING RESULTS OF ONGOING RESEARCH IN THE FIELD OF EPIGENETIC DRUGS THAT COULD REPRESENT ADDITIONAL OPTIONS IN OUR THERAPEUTIC ARMAMENTARIUM FOR PATIENTS WITH CHRONIC KIDNEY DISEASE. 2011 11 4456 36 MOLECULAR MECHANISMS IN RENAL DEGENERATIVE DISEASE. CHRONIC KIDNEY DISEASE (CKD) HAS BECOME A MAJOR PUBLIC HEALTH PROBLEM WORLDWIDE. THEREFORE, A CONSIDERABLE EFFORT IS CURRENTLY DIRECTED TO UNDERSTAND THE MOLECULAR MECHANISMS OF RENAL DEGENERATIVE PROCESSES. REGARDLESS OF THEIR INITIATING CAUSE, ALL CHRONIC KIDNEY DISEASES (CKD) DEVELOP AT SOME LEVEL ORGAN FIBROSIS THAT INTERFERES WITH KIDNEY FUNCTION. THIS IS ALSO TRUE FOR THE TWO MOST COMMON INHERITED CKD SYNDROMES, NEPHRONOPHTHITIS AND POLYCYSTIC KIDNEY DISEASE, WHOSE PRIMARY DEFECTS RESIDE WITHIN THE CILIUM OF KIDNEY EPITHELIAL CELLS. A COHORT OF ELEGANT RECENT STUDIES HAS ELICITED THE ROLE OF THE PRIMARY CILIUM AS A VERSATILE MECHANOSENSORY ORGANELLE THAT ALSO MIGHT COORDINATE CROSS-TALK BETWEEN MULTIPLE SIGNALING PATHWAYS. IN ADDITION, EPIGENETIC MECHANISMS ARE NOW REALIZED TO BE ESSENTIAL IN THE MAINTENANCE OF ADULT RENAL ARCHITECTURE. IN THIS REVIEW, WE WILL DISCUSS RECENT ADVANCES IN OUR UNDERSTANDING OF THE SIGNALING SYSTEMS IMPLICATED IN KIDNEY HOMEOSTASIS AND REPAIR. 2010 12 2579 22 EPIGENETICS OF KIDNEY DISEASE. DNA METHYLATION AND HISTONE MODIFICATIONS DETERMINE RENAL PROGRAMMING AND THE DEVELOPMENT AND PROGRESSION OF RENAL DISEASE. THE IDENTIFICATION OF THE WAY IN WHICH THE RENAL CELL EPIGENOME IS ALTERED BY ENVIRONMENTAL MODIFIERS DRIVING THE ONSET AND PROGRESSION OF RENAL DISEASES HAS EXTENDED OUR UNDERSTANDING OF THE PATHOPHYSIOLOGY OF KIDNEY DISEASE PROGRESSION. IN THIS REVIEW, WE FOCUS ON CURRENT KNOWLEDGE CONCERNING THE IMPLICATIONS OF EPIGENETIC MODIFICATIONS DURING RENAL DISEASE FROM EARLY DEVELOPMENT TO CHRONIC KIDNEY DISEASE PROGRESSION INCLUDING RENAL FIBROSIS, DIABETIC NEPHROPATHY AND THE TRANSLATIONAL POTENTIAL OF IDENTIFYING NEW BIOMARKERS AND TREATMENTS FOR THE PREVENTION AND THERAPY OF CHRONIC KIDNEY DISEASE AND END-STAGE KIDNEY DISEASE. 2017 13 5364 31 RECENT ADVANCES IN EPIGENETICS OF AGE-RELATED KIDNEY DISEASES. RENAL AGING HAS ATTRACTED INCREASING ATTENTION IN TODAY'S AGING SOCIETY, AS ELDERLY PEOPLE WITH ADVANCED AGE ARE MORE SUSCEPTIBLE TO VARIOUS KIDNEY DISORDERS SUCH AS ACUTE KIDNEY INJURY (AKI) AND CHRONIC KIDNEY DISEASE (CKD). THERE IS NO CLEAR-CUT UNIVERSAL MECHANISM FOR IDENTIFYING AGE-RELATED KIDNEY DISEASES, AND THEREFORE, THEY POSE A CONSIDERABLE MEDICAL AND PUBLIC HEALTH CHALLENGE. EPIGENETICS REFERS TO THE STUDY OF HERITABLE MODIFICATIONS IN THE REGULATION OF GENE EXPRESSION THAT DO NOT REQUIRE CHANGES IN THE UNDERLYING GENOMIC DNA SEQUENCE. A VARIETY OF EPIGENETIC MODIFIERS SUCH AS HISTONE DEACETYLASES (HDAC) INHIBITORS AND DNA METHYLTRANSFERASE (DNMT) INHIBITORS HAVE BEEN PROPOSED AS POTENTIAL BIOMARKERS AND THERAPEUTIC TARGETS IN NUMEROUS FIELDS INCLUDING CARDIOVASCULAR DISEASES, IMMUNE SYSTEM DISEASE, NERVOUS SYSTEM DISEASES, AND NEOPLASMS. ACCUMULATING EVIDENCE IN RECENT YEARS INDICATES THAT EPIGENETIC MODIFICATIONS HAVE BEEN IMPLICATED IN RENAL AGING. HOWEVER, NO PREVIOUS SYSTEMATIC REVIEW HAS BEEN PERFORMED TO SYSTEMATICALLY GENERALIZE THE RELATIONSHIP BETWEEN EPIGENETICS AND AGE-RELATED KIDNEY DISEASES. IN THIS REVIEW, WE AIM TO SUMMARIZE THE RECENT ADVANCES IN EPIGENETIC MECHANISMS OF AGE-RELATED KIDNEY DISEASES AS WELL AS DISCUSS THE APPLICATION OF EPIGENETIC MODIFIERS AS POTENTIAL BIOMARKERS AND THERAPEUTIC TARGETS IN THE FIELD OF AGE-RELATED KIDNEY DISEASES. IN SUMMARY, THE MAIN TYPES OF EPIGENETIC PROCESSES INCLUDING DNA METHYLATION, HISTONE MODIFICATIONS, NON-CODING RNA (NCRNA) MODULATION HAVE ALL BEEN IMPLICATED IN THE PROGRESSION OF AGE-RELATED KIDNEY DISEASES, AND THERAPEUTIC TARGETING OF THESE PROCESSES WILL YIELD NOVEL THERAPEUTIC STRATEGIES FOR THE PREVENTION AND/OR TREATMENT OF AGE-RELATED KIDNEY DISEASES. 2022 14 2195 33 EPIGENETIC MODIFICATION MECHANISMS INVOLVED IN INFLAMMATION AND FIBROSIS IN RENAL PATHOLOGY. THE GROWING INCIDENCE OF OBESITY, HYPERTENSION, AND DIABETES, COUPLED WITH THE AGING OF THE POPULATION, IS INCREASING THE PREVALENCE OF RENAL DISEASES IN OUR SOCIETY. CHRONIC KIDNEY DISEASE (CKD) IS CHARACTERIZED BY PERSISTENT INFLAMMATION, FIBROSIS, AND LOSS OF RENAL FUNCTION LEADING TO END-STAGE RENAL DISEASE. NOWADAYS, CKD TREATMENT HAS LIMITED EFFECTIVENESS UNDERSCORING THE IMPORTANCE OF THE DEVELOPMENT OF INNOVATIVE THERAPEUTIC OPTIONS. RECENT STUDIES HAVE IDENTIFIED HOW EPIGENETIC MODIFICATIONS PARTICIPATE IN THE SUSCEPTIBILITY TO CKD AND HAVE EXPLAINED HOW THE ENVIRONMENT INTERACTS WITH THE RENAL CELL EPIGENOME TO CONTRIBUTE TO RENAL DAMAGE. EPIGENETIC MECHANISMS REGULATE CRITICAL PROCESSES INVOLVED IN GENE REGULATION AND DOWNSTREAM CELLULAR RESPONSES. THE MOST RELEVANT EPIGENETIC MODIFICATIONS THAT PLAY A CRITICAL ROLE IN RENAL DAMAGE INCLUDE DNA METHYLATION, HISTONE MODIFICATIONS, AND CHANGES IN MIRNA LEVELS. IMPORTANTLY, THESE EPIGENETIC MODIFICATIONS ARE REVERSIBLE AND, THEREFORE, A SOURCE OF POTENTIAL THERAPEUTIC TARGETS. HERE, WE WILL EXPLAIN HOW EPIGENETIC MECHANISMS MAY REGULATE ESSENTIAL PROCESSES INVOLVED IN RENAL PATHOLOGY AND HIGHLIGHT SOME POSSIBLE EPIGENETIC THERAPEUTIC STRATEGIES FOR CKD TREATMENT. 2018 15 2293 36 EPIGENETIC REGULATION IN THE ACUTE KIDNEY INJURY TO CHRONIC KIDNEY DISEASE TRANSITION. EPIGENETIC MODIFICATIONS HAVE EMERGED AS A NEW, IMPORTANT CONTRIBUTOR TO GENE EXPRESSION REGULATION IN BOTH NORMAL AND PATHOPHYSIOLOGICAL CONDITIONS. EPIGENETICS HAVE BEEN STUDIED IN MANY DISEASES AND CONDITIONS SUCH AS ACUTE KIDNEY INJURY (AKI), A SYNDROME WITH A HIGH PREVALENCE THAT CARRIES A POOR PROGNOSIS WITH INCREASED MORBIDITY AND MORTALITY. IN ADDITION, IT HAS RECENTLY BEEN SHOWN THAT AKI INCREASES THE RISK FOR THE DEVELOPMENT OF CHRONIC KIDNEY DISEASE (CKD). THE SPECIFIC MOLECULAR MECHANISMS BY WHICH AKI INCREASES THE RISK OF CKD AND END STAGE RENAL DISEASE (ESRD) REMAIN UNKNOWN, ALTHOUGH THERE IS NEW EVIDENCE SUPPORTING A ROLE OF EPIGENETIC CHANGES. THE MOST STUDIED EPIGENETIC REGULATIONS IN AKI ARE CHROMATIN COMPACTION, DNA METHYLATION, AND HISTONE ACETYLATION/DEACETYLATION. THESE MODIFICATIONS PREDOMINANTLY INCREASE THE PRODUCTION OF PRO-INFLAMMATORY AND PROFIBROTIC CYTOKINES SUCH AS: MONOCYTE CHEMOATTRACTANT PROTEIN-1 (MCP-1), COMPLEMENT PROTEIN 3 (C3), TRANSFORMING GROWTH FACTOR BETA (TGF-BETA) THAT HAVE BEEN SHOWN FOR PERPETUATING INFLAMMATION, PROMOTING EPITHELIAL-TO-MESENCHYMAL TRANSITION (EMT) AND ULTIMATELY CAUSING RENAL FIBROSIS. A REVIEW OF EPIGENETIC MECHANISMS, THE PATHOPHYSIOLOGY OF AKI AND RECENT STUDIES THAT IMPLICATE EPIGENETIC MODIFICATIONS IN AKI AND IN THE TRANSITION TO CKD ARE DISCUSSED BELOW. 2015 16 97 26 A PRIMER ON THE EPIGENETICS OF KIDNEY FIBROSIS. DESPITE EXTENSIVE KNOWLEDGE OF THE VARIOUS MOLECULAR PATHWAYS THAT CONTRIBUTE TO TUBULOINTERSTITIAL FIBROSIS, IT REMAINS AN UNSOLVED QUESTION WHY THE PROGRESSION RATE OF CHRONIC KIDNEY DISEASE VARIES SUBSTANTIALLY FROM PATIENT TO PATIENT, EVEN AMONG PATIENTS WITH COMMON UNDERLYING NEPHROPATHIES AND COMORBIDITIES. POSSIBLE EXPLANATIONS FOR DIFFERENT SUSCEPTIBILITIES OF INDIVIDUAL PATIENTS TO DEVELOP END-STAGE RENAL FAILURE INCLUDE GENETIC OR EPIGENETIC VARIATIONS, WHICH MODIFY HOW INDIVIDUAL PATIENTS RESPOND TO KIDNEY INJURY. HERE WE REVIEW PRINCIPLES OF EPIGENETIC MECHANISMS IN CONTEXT OF CHRONIC KIDNEY DISEASE AND DISCUSS HOW SUCH INSIGHTS MAY BE UTILIZED FOR FUTURE THERAPEUTIC STRATEGIES AND MAY LEAD TO NOVEL DIAGNOSTIC TOOLS IN THE FUTURE. 2012 17 2982 34 GENETIC CONSIDERATIONS IN PEDIATRIC CHRONIC KIDNEY DISEASE. CHRONIC KIDNEY DISEASE (CKD) IN CHILDREN IS AN IRREVERSIBLE PROCESS THAT, IN SOME CASES, MAY LEAD TO END-STAGE RENAL DISEASE. THE MAJORITY OF CHILDREN WITH CKD HAVE A CONGENITAL DISORDER OF THE KIDNEY OR UROLOGICAL TRACT ARISING FROM BIRTH. THERE IS STRONG EVIDENCE FOR BOTH A GENETIC AND EPIGENETIC COMPONENT TO PROGRESSION OF CKD. UTILIZATION OF GENE-MAPPING STRATEGIES, RANGING FROM GENOME-WIDE ASSOCIATION STUDIES TO SINGLE-NUCLEOTIDE POLYMORPHISM ANALYSIS, SERVES TO IDENTIFY POTENTIAL GENETIC VARIANTS THAT MAY LEND TO DISEASE VARIATION. GENOME-WIDE ASSOCIATION STUDIES EVALUATING POPULATION-BASED DATA HAVE IDENTIFIED DIFFERENT LOCI ASSOCIATED WITH CKD PROGRESSION. ANALYSIS OF SINGLE-NUCLEOTIDE POLYMORPHISMS ON AN INDIVIDUAL LEVEL SUGGESTS THAT SECONDARY SYSTEMIC SEQUELAE OF CKD ARE CLOSELY RELATED TO DYSFUNCTION OF THE CARDIOVASCULAR-INFLAMMATORY AXIS AND MAY LEAD TO ADVANCED CARDIOVASCULAR DISEASE THROUGH ABNORMAL VASCULAR CALCIFICATION AND ACTIVATION OF THE RENIN-ANGIOTENSIN SYSTEM. SIMILARLY, GENETIC VARIANTS AFFECTING CYTOKINE CONTROL, FIBROSIS, AND PARENCHYMAL DEVELOPMENT MAY MODULATE CKD THROUGH DEVELOPMENT AND ACCELERATION OF RENAL INTERSTITIAL FIBROSIS. EPIGENETIC STUDIES EVALUATE MODIFICATION OF THE GENOME THROUGH DNA METHYLATION, HISTONE MODIFICATION, OR RNA INTERFERENCE, WHICH MAY BE DIRECTLY INFLUENCED BY EXTERNAL OR ENVIRONMENTAL FACTORS DIRECTING GENOMIC EXPRESSION. LASTLY, IMPROVED UNDERSTANDING OF THE GENETIC AND EPIGENETIC CONTRIBUTION TO CKD PROGRESSION MAY ALLOW PROVIDERS TO IDENTIFY A POPULATION AT ACCELERATED RISK FOR DISEASE PROGRESSION AND APPLY NOVEL THERAPIES TARGETED AT THE GENETIC MECHANISM OF DISEASE. 2016 18 5370 25 RECENT ADVANCES IN UNDERSTANDING OF CHRONIC KIDNEY DISEASE. CHRONIC KIDNEY DISEASE (CKD) IS DEFINED AS ANY CONDITION THAT CAUSES REDUCED KIDNEY FUNCTION OVER A PERIOD OF TIME. FIBROSIS, TUBULAR ATROPHY AND INTERSTITIAL INFLAMMATION ARE THE HALLMARK OF PATHOLOGICAL FEATURES IN CKD. REGARDLESS OF INITIAL INSULT, CKD HAS SOME COMMON PATHWAYS LEADING CKD TO END-STAGE KIDNEY DISEASE, INCLUDING HYPOXIA IN THE TUBULOINTERSTITIUM AND PROTEINURIA. RECENT ADVANCES IN GENOME EDITING TECHNOLOGIES AND STEM CELL RESEARCH GIVE GREAT INSIGHTS TO UNDERSTAND THE PATHOGENESIS OF CKD, INCLUDING IDENTIFICATIONS OF THE ORIGINS OF RENAL MYOFIBROBLASTS AND TUBULAR EPITHELIAL CELLS UPON INJURY. ENVIRONMENTAL FACTORS SUCH AS HYPOXIA, OXIDATIVE STRESS, AND EPIGENETIC FACTORS IN RELATION TO CKD ARE ALSO DISCUSSED. 2015 19 859 30 CHROMATIN DYNAMICS IN KIDNEY DEVELOPMENT AND FUNCTION. EPIGENETIC MECHANISMS ARE FUNDAMENTAL KEY FEATURES OF DEVELOPING CELLS CONNECTING DEVELOPMENTAL REGULATORY FACTORS TO CHROMATIN MODIFICATION. CHANGES IN THE ENVIRONMENT DURING RENAL DEVELOPMENT CAN HAVE LONG-LASTING EFFECTS ON THE PERMANENT TISSUE STRUCTURE AND THE LEVEL OF EXPRESSION OF IMPORTANT FUNCTIONAL GENES. THESE CHANGES ARE BELIEVED TO CONTRIBUTE TO KIDNEY DISEASE OCCURRENCE AND PROGRESSION. ALTHOUGH THE MECHANISMS OF EARLY PATTERNING AND CELL FATE HAVE BEEN WELL DESCRIBED FOR RENAL DEVELOPMENT, LITTLE IS KNOWN ABOUT ASSOCIATED EPIGENETIC MODIFICATIONS AND THEIR IMPACT ON HOW GENES INTERACT TO SPECIFY THE RENAL EPITHELIAL CELLS OF NEPHRONS AND HOW THIS SPECIFICATION IS RELEVANT TO MAINTAINING NORMAL RENAL FUNCTION. A BETTER UNDERSTANDING OF THE RENAL CELL-SPECIFIC EPIGENETIC MODIFICATIONS AND THE INTERACTION OF DIFFERENT CELL TYPES TO FORM THIS HIGHLY COMPLEX ORGAN WILL NOT ONLY HELP TO BETTER UNDERSTAND DEVELOPMENTAL DEFECTS AND EARLY LOSS OF KIDNEY FUNCTION IN CHILDREN, BUT ALSO HELP TO UNDERSTAND AND IMPROVE CHRONIC DISEASE PROGRESSION, CELL REGENERATION AND RENAL AGING. 2014 20 6451 39 THERAPIES TARGETING EPIGENETIC ALTERATIONS IN ACUTE KIDNEY INJURY-TO-CHRONIC KIDNEY DISEASE TRANSITION. ACUTE KIDNEY INJURY (AKI) WAS PREVIOUSLY THOUGHT TO BE A MERELY TRANSIENT EVENT; HOWEVER, RECENT EPIDEMIOLOGICAL EVIDENCE SUPPORTS THE EXISTENCE OF A CAUSAL RELATIONSHIP BETWEEN AKI EPISODES AND SUBSEQUENT PROGRESSION TO CHRONIC KIDNEY DISEASE (CKD). ALTHOUGH THE PATHOPHYSIOLOGY OF THIS AKI-TO-CKD TRANSITION IS NOT FULLY UNDERSTOOD, IT IS MEDIATED BY THE INTERPLAY AMONG MULTIPLE COMPONENTS OF THE KIDNEY INCLUDING TUBULAR EPITHELIAL CELLS, ENDOTHELIAL CELLS, PERICYTES, INFLAMMATORY CELLS, AND MYOFIBROBLASTS. EPIGENETIC ALTERATIONS INCLUDING HISTONE MODIFICATION, DNA METHYLATION, NON-CODING RNAS, AND CHROMATIN CONFORMATIONAL CHANGES, ARE ALSO EXPECTED TO BE LARGELY INVOLVED IN THE PATHOPHYSIOLOGY AS A "MEMORY" OF THE INITIAL INJURY THAT CAN PERSIST AND PREDISPOSE TO CHRONIC PROGRESSION OF FIBROSIS. EACH EPIGENETIC MODIFICATION HAS A GREAT POTENTIAL AS A THERAPEUTIC TARGET OF AKI-TO-CKD TRANSITION; TIMELY AND TARGET-SPECIFIC EPIGENETIC INTERVENTIONS TO THE VARIOUS TEMPORAL STAGES OF AKI-TO-CKD TRANSITION WILL BE THE KEY TO FUTURE THERAPEUTIC APPLICATIONS IN CLINICAL PRACTICE. THIS REVIEW ELABORATES ON THE LATEST KNOWLEDGE OF EACH MECHANISM AND THE CURRENTLY AVAILABLE THERAPEUTIC AGENTS THAT TARGET EPIGENETIC MODIFICATION IN THE CONTEXT OF AKI-TO-CKD TRANSITION. FURTHER STUDIES WILL ELUCIDATE MORE DETAILED MECHANISMS AND NOVEL THERAPEUTIC TARGETS OF AKI-TO-CKD TRANSITION. 2022