1 6429 140 THE UPREGULATION OF NLRP3 INFLAMMASOME IN DORSAL ROOT GANGLION BY TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE 2 (TET2) CONTRIBUTED TO DIABETIC NEUROPATHIC PAIN IN MICE. BACKGROUND: THE NUCLEOTIDE OLIGOMERIZATION DOMAIN (NOD)-LIKE RECEPTOR FAMILY PYRIN DOMAIN CONTAINING 3 (NLRP3) IN DORSAL ROOT GANGLION (DRG) CONTRIBUTES TO PAIN HYPERSENSITIVITY IN MULTIPLE NEUROPATHIC PAIN MODELS, BUT THE FUNCTION OF THE NLRP3 IN DIABETIC NEUROPATHIC PAIN (DNP) AND THE REGULATION MECHANISM ARE STILL LARGELY UNKNOWN. EPIGENETIC REGULATION PLAYS A VITAL ROLE IN THE CONTROLLING OF GENE EXPRESSION. TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE 2 (TET2) IS A DNA DEMETHYLASE THAT CONTRIBUTES TO TRANSCRIPTIONAL ACTIVATION. TET2 IS ALSO INVOLVED IN HIGH GLUCOSE (HG)-INDUCED PATHOLOGY. METHODS: DNP WAS INDUCED IN MICE VIA THE INTRAPERITONEAL INJECTION OF STREPTOZOTOCIN (STZ) FOR FIVE CONSECUTIVE DAYS AND THE MECHANICAL THRESHOLD WAS EVALUATED IN STZ-DIABETIC MICE BY USING VON FREY HAIRS. THE EXPRESSION LEVEL OF THE NLRP3 PATHWAY AND TET2 IN DRG WERE DETERMINED THROUGH MOLECULAR BIOLOGY EXPERIMENTS. THE REGULATION OF THE NLRP3 PATHWAY BY TET2 WAS EXAMINED IN IN VITRO AND IN VIVO CONDITIONS. RESULTS: IN THE PRESENT RESEARCH, WE FIRST ESTABLISHED THE DNP MODEL AND FOUND THAT NLRP3 PATHWAY WAS ACTIVATED IN DRG. THE TREATMENT OF NLRP3 INHIBITOR MCC950 ALLEVIATED THE MECHANICAL ALLODYNIA OF DNP MICE. THEN WE REVEALED THAT IN STZ-DIABETIC MICE DRG, THE GENOMIC DNA WAS DEMETHYLATED, AND THE EXPRESSION OF DNA DEMETHYLASE TET2 WAS INCREASED EVIDENTLY. USING RNA-SEQUENCING ANALYSIS, WE FOUND THAT THE EXPRESSION OF TXNIP, A GENE THAT ENCODES A THIOREDOXIN-INTERACTING PROTEIN (TXNIP) WHICH MEDIATES NLRP3 ACTIVATION, WAS ELEVATED IN THE DRG AFTER STZ TREATMENT. IN ADDITION, KNOCKING DOWN OF TET2 EXPRESSION IN DRG USING TET2-SIRNA SUPPRESSED THE MRNA EXPRESSION OF TXNIP AND SUBSEQUENTLY INHIBITED THE EXPRESSION/ACTIVATION OF NLRP3 INFLAMMASOME IN VITRO AND IN VIVO AS WELL AS RELIEVED THE PAIN SENSITIVITY OF DNP ANIMALS. CONCLUSION: THE RESULTS SUGGESTED THAT THE UPREGULATION OF THE TXNIP/NLRP3 PATHWAY BY TET2 IN DRG WAS INVOLVED IN THE PAIN HYPERSENSITIVITY OF THE DNP MODEL. 2022 2 2470 47 EPIGENETIC TRANSCRIPTIONAL ACTIVATION OF MONOCYTE CHEMOTACTIC PROTEIN 3 CONTRIBUTES TO LONG-LASTING NEUROPATHIC PAIN. A MULTIPLEX ANALYSIS FOR PROFILING THE EXPRESSION OF CANDIDATE GENES ALONG WITH EPIGENETIC MODIFICATION MAY LEAD TO A BETTER UNDERSTANDING OF THE COMPLEX MACHINERY OF NEUROPATHIC PAIN. IN THE PRESENT STUDY, WE FOUND THAT PARTIAL SCIATIC NERVE LIGATION MOST REMARKABLY INCREASED THE EXPRESSION OF MONOCYTE CHEMOTACTIC PROTEIN 3 (MCP-3, KNOWN AS CCL7) A TOTAL OF 33 541 GENES IN THE SPINAL CORD, WHICH LASTED FOR 4 WEEKS. THIS INCREASE IN MCP-3 GENE TRANSCRIPTION WAS ACCOMPANIED BY THE DECREASED TRIMETHYLATION OF HISTONE H3 AT LYS27 AT THE MCP-3 PROMOTER. THE INCREASED MCP-3 EXPRESSION ASSOCIATED WITH ITS EPIGENETIC MODIFICATION OBSERVED IN THE SPINAL CORD WAS ALMOST ABOLISHED IN INTERLEUKIN 6 KNOCKOUT MICE WITH PARTIAL SCIATIC NERVE LIGATION. CONSISTENT WITH THESE FINDINGS, A SINGLE INTRATHECAL INJECTION OF RECOMBINANT PROTEINS OF INTERLEUKIN 6 SIGNIFICANTLY INCREASED MCP-3 MESSENGER RNA WITH A DECREASE IN THE LEVEL OF LYS27 TRIMETHYLATION OF HISTONE H3 AT THE MCP-3 PROMOTER IN THE SPINAL CORD OF MICE. FURTHERMORE, DELETION OF THE C-C CHEMOKINE RECEPTOR TYPE 2 (CCR2) GENE, WHICH ENCODES A RECEPTOR FOR MCP-3, FAILED TO AFFECT THE ACCELERATION OF MCP-3 EXPRESSION IN THE SPINAL CORD AFTER PARTIAL SCIATIC NERVE LIGATION. A ROBUST INCREASE IN MCP-3 PROTEIN, WHICH LASTED FOR UP TO 2 WEEKS AFTER SURGERY, IN THE DORSAL HORN OF THE SPINAL CORD OF MICE WITH PARTIAL SCIATIC NERVE LIGATION WAS SEEN MOSTLY IN ASTROCYTES, BUT NOT MICROGLIA OR NEURONS. ON THE OTHER HAND, THE INCREASES IN BOTH MICROGLIA AND ASTROCYTES IN THE SPINAL CORD BY PARTIAL SCIATIC NERVE LIGATION WERE MOSTLY ABOLISHED IN INTERLEUKIN 6 KNOCKOUT MICE. MOREOVER, THIS INCREASE IN MICROGLIA WAS ALMOST ABOLISHED BY CCR2 GENE DELETION, WHEREAS THE INCREASE IN ASTROCYTES WAS NOT AFFECTED IN NERVE-LIGATED MICE THAT LACKED THE CCR2 GENE. WE ALSO FOUND THAT EITHER IN VIVO OR IN VITRO TREATMENT WITH MCP-3 CAUSED ROBUST MICROGLIA ACTIVATION. UNDER THESE CONDITIONS, INTRATHECAL ADMINISTRATION OF MCP-3 ANTIBODY SUPPRESSED THE INCREASE IN MICROGLIA WITHIN THE MOUSE SPINAL CORD AND NEUROPATHIC PAIN-LIKE BEHAVIOURS AFTER NERVE INJURY. WITH THE USE OF A FUNCTIONAL MAGNETIC RESONANCE IMAGING ANALYSIS, WE DEMONSTRATED THAT A SINGLE INTRATHECAL INJECTION OF MCP-3 INDUCED DRAMATIC INCREASES IN SIGNAL INTENSITY IN PAIN-RELATED BRAIN REGIONS. THESE FINDINGS SUGGEST THAT INCREASED MCP-3 EXPRESSION ASSOCIATED WITH INTERLEUKIN 6 DEPENDENT EPIGENETIC MODIFICATION AT THE MCP-3 PROMOTER AFTER NERVE INJURY, MOSTLY IN SPINAL ASTROCYTES, MAY SERVE TO FACILITATE ASTROCYTE-MICROGLIA INTERACTION IN THE SPINAL CORD AND COULD PLAY A CRITICAL ROLE IN THE NEUROPATHIC PAIN-LIKE STATE. 2013 3 6148 40 THE EXPRESSION OF TRANSCRIPTION FACTORS MECP2 AND CREB IS MODULATED IN INFLAMMATORY PELVIC PAIN. EARLY ACTIVATION OF TRANSCRIPTION FACTORS IS ONE OF THE EPIGENETIC MECHANISMS CONTRIBUTING TO THE INDUCTION AND MAINTENANCE OF CHRONIC PAIN STATES. PREVIOUS STUDIES IDENTIFIED THE CHANGES IN A NUMBER OF NOCICEPTION-RELATED GENES, SUCH AS CALCITONIN GENE-RELATED PEPTIDE (CGRP), SUBSTANCE P (SP), AND BRAIN-DERIVED NEUROTROPIC FACTOR (BDNF) IN THE PELVIC ORGANS AFTER TRANSIENT COLONIC INFLAMMATION. THE GENE AND PROTEIN EXPRESSION OF THESE NEUROPEPTIDES COULD BE MODULATED BY TRANSCRIPTION FACTORS METHYL-CPG-BINDING PROTEIN 2 (MECP2) AND CAMP RESPONSE ELEMENT-BINDING PROTEIN (CREB). IN THIS STUDY, WE AIMED TO EVALUATE TIME-DEPENDENT CHANGES IN THE EXPRESSION LEVELS OF MECP2 AND CREB IN THE LUMBOSACRAL (LS) SPINAL CORD AND SENSORY GANGLIA AFTER INFLAMMATION-INDUCED PELVIC PAIN IN RAT. ADULT SPRAGUE-DAWLEY RATS WERE TREATED WITH 2,4,6-TRINITROBENZENESULFONIC ACID (TNBS) TO INDUCE TRANSIENT COLONIC INFLAMMATION. LS (L6-S2) SPINAL CORD SEGMENTS AND RESPECTIVE DORSAL ROOT GANGLIAS (DRGS) WERE ISOLATED FROM CONTROL AND EXPERIMENTAL ANIMALS AT 1, 2, 6, 24 H AND 3 DAYS POST-TNBS TREATMENT. IMMUNOHISTOCHEMICAL (IHC) LABELING AND WESTERN BLOTTING EXPERIMENTS WERE PERFORMED TO ASSESS THE EXPRESSION OF MECP2, CREB AND THEIR PHOSPHORYLATED FORMS. TOTAL MECP2 EXPRESSION, BUT NOT PHOSPHORYLATED P-MECP2 (PS421MECP2) EXPRESSION WAS DETECTED IN THE CELLS OF THE SPINAL DORSAL HORN UNDER CONTROL CONDITIONS. COLONIC INFLAMMATION TRIGGERED A SIGNIFICANT DECREASE IN THE NUMBER OF MECP2-EXPRESSING NEURONS IN PARALLEL WITH ELEVATED NUMBERS OF PS421MECP2-EXPRESSING CELLS AT 2 H AND 6 H POST-TNBS. THE MAJORITY OF MECP2-POSITIVE CELLS (80 +/- 6%) CO-EXPRESSED CREB. TNBS TREATMENT CAUSED A TRANSIENT UP-REGULATION OF CREB-EXPRESSING CELLS AT 1 H POST-TNBS ONLY. THE NUMBER OF CELLS EXPRESSING PHOSPHORYLATED CREB (PS133CREB) DID NOT CHANGE AT 1 H AND 2 H POST-TNBS, BUT WAS DOWN-REGULATED BY THREE FOLDS AT 6 H POST-TNBS. ANALYSIS OF DRG SECTIONS REVEALED THAT THE NUMBER OF MECP2-POSITIVE NEURONS WAS UP-REGULATED BY TNBS TREATMENT, REACHING THREE-FOLD INCREASE AT 2 H POST-TNBS, AND EIGHT-FOLD INCREASE AT 6 H POST-TNBS (P