1 5625 100 SELECTIVE CLASS I HISTONE DEACETYLASE INHIBITORS SUPPRESS PERSISTENT SPONTANEOUS NOCICEPTION AND THERMAL HYPERSENSITIVITY IN A RAT MODEL OF BEE VENOM-INDUCED INFLAMMATORY PAIN. TO CONFIRM WHETHER CLASS I HISTONE DEACETYLASE INHIBITORS (HDACIS) ARE EFFECTIVE IN RELIEF OF PERIPHERAL INFLAMMATORY PAIN, THE EFFECTS OF TWO SELECTIVE INHIBITORS, MS-275 AND MGCD0103, WERE STUDIED IN RATS INFLAMED BY SUBCUTANEOUS (S.C.) INJECTION OF BEE VENOM (BV). THE BV TEST IS CHARACTERIZED BY DISPLAYING BOTH PERSISTENT SPONTANEOUS NOCICEPTION (PSN) AND PRIMARY HYPERSENSITIVITY. INTRATHECAL (I.T.) PRE-TREATMENT OF EITHER MS-275 OR MGCD0103 WITH A SINGLE DOSE OF 60 NMOL/20 MUL RESULTED IN PROFOUND SUPPRESSION OF BOTH PSN AND PRIMARY THERMAL HYPERSENSITIVITY BUT WITHOUT SIGNIFICANT INFLUENCE UPON THE PRIMARY MECHANICAL HYPERSENSITIVITY AND MIRROR-IMAGE THERMAL HYPERSENSITIVITY. MOREOVER, THE UP-REGULATION OF BOTH HDAC1 AND HDAC2 INDUCED BY S.C. BV INJECTION WAS COMPLETELY SUPPRESSED BY I.T. PRE-TREATMENT OF MS-275. THE PRESENT RESULTS PROVIDE WITH ANOTHER NEW LINE OF EVIDENCE SHOWING INVOLVEMENT OF EPIGENETIC REGULATION OF CHROMATIN STRUCTURE BY HDAC1/2-MEDIATED HISTONE HYPOACETYLATION IN THE BV-INDUCED PSN AND THERMAL HYPERSENSITIVITY AND DEMONSTRATE THE BENEFICIAL EFFECTS OF CLASS I HDACIS IN PREVENTION OF PERIPHERAL INFLAMMATORY PAIN FROM OCCURRING. 2015 2 1689 33 DUAL HDAC/BRD4 INHIBITORS RELIEVES NEUROPATHIC PAIN BY ATTENUATING INFLAMMATORY RESPONSE IN MICROGLIA AFTER SPARED NERVE INJURY. DESPITE THE EFFORT ON DEVELOPING NEW TREATMENTS, THERAPY FOR NEUROPATHIC PAIN IS STILL A CLINICAL CHALLENGE AND COMBINATION THERAPY REGIMES OF TWO OR MORE DRUGS ARE OFTEN NEEDED TO IMPROVE EFFICACY. ACCUMULATING EVIDENCE SHOWS AN ALTERED EXPRESSION AND ACTIVITY OF HISTONE ACETYLATION ENZYMES IN CHRONIC PAIN CONDITIONS AND RESTORATION OF THESE ABERRANT EPIGENETIC MODIFICATIONS PROMOTES PAIN-RELIEVING ACTIVITY. RECENT STUDIES SHOWED A SYNERGISTIC ACTIVITY IN NEUROPATHIC PAIN MODELS BY COMBINATION OF HISTONE DEACETYLASES (HDACS) AND BROMODOMAIN AND EXTRA-TERMINAL DOMAIN (BET) INHIBITORS. ON THESE PREMISES, THE PRESENT STUDY INVESTIGATED THE PHARMACOLOGICAL PROFILE OF NEW DUAL HDAC/BRD4 INHIBITORS, NAMED SUM52 AND SUM35, IN THE SPARED NERVE INJURY (SNI) MODEL IN MICE AS INNOVATIVE STRATEGY TO SIMULTANEOUSLY INHIBIT HDACS AND BETS. INTRANASAL ADMINISTRATION OF SUM52 AND SUM35 ATTENUATED THERMAL AND MECHANICAL HYPERSENSITIVITY IN THE ABSENCE OF LOCOMOTOR SIDE EFFECTS. BOTH DUAL INHIBITORS SHOWED A PREFERENTIAL INTERACTION WITH BRD4-BD2 DOMAIN, AND SUM52 RESULTED THE MOST ACTIVE COMPOUND. SUM52 REDUCED MICROGLIA-MEDIATED SPINAL NEUROINFLAMMATION IN SPINAL CORD SECTIONS OF SNI MICE AS SHOWED BY REDUCTION OF IBA1 IMMUNOSTAINING, INDUCIBLE NITRIC OXIDE SYNTHASE (INOS) EXPRESSION, P65 NUCLEAR FACTOR-KAPPAB (NF-KAPPAB) AND P38 MAPK OVER-PHOSPHORYLATION. A ROBUST DECREASE OF THE SPINAL PROINFLAMMATORY CYTOKINES CONTENT (IL-6, IL-1SS) WAS ALSO OBSERVED AFTER SUM52 TREATMENT. PRESENT RESULTS, SHOWING THE PAIN-RELIEVING ACTIVITY OF HDAC/BRD4 DUAL INHIBITORS, INDICATE THAT THE SIMULTANEOUS MODULATION OF BET AND HDAC ACTIVITY BY A SINGLE MOLECULE ACTING AS MULTI-TARGET AGENT MIGHT REPRESENT A PROMISE FOR NEUROPATHIC PAIN RELIEF. 2022 3 532 24 ASTROCYTIC C-JUN N-TERMINAL KINASE-HISTONE DEACETYLASE-2 CASCADE CONTRIBUTES TO GLUTAMATE TRANSPORTER-1 DECREASE AND MECHANICAL ALLODYNIA FOLLOWING PERIPHERAL NERVE INJURY IN RATS. DECREASE OF GLUTAMATE TRANSPORTER-1 (GLT-1) IN THE SPINAL DORSAL HORN AFTER NERVE INJURY INDUCES ENHANCED EXCITATORY TRANSMISSION AND CAUSES PERSISTENT PAIN. HISTONE DEACETYLASES (HDACS)-CATALYZED DEACETYLATION MIGHT CONTRIBUTE TO THE DECREASE OF GLT-1, WHILE THE DETAILED MECHANISMS HAVE YET TO BE FULLY ELABORATED. SPINAL NERVE LIGATION (SNL) INDUCED SIGNIFICANT INCREASES OF HDAC2 AND DECREASES OF GLT-1 IN SPINAL ASTROCYTES. INTRATHECAL INFUSION OF THE HDAC2 INHIBITORS ATTENUATED THE DECREASE OF GLT-1 AND ENHANCED PHOSPHORYLATION OF GLUTAMATE RECEPTORS. GLT-1 AND PHOSPHORYLATED C-JUN N-TERMINAL KINASE (JNK) WERE HIGHLY COLOCALIZED IN THE SPINAL CORD, AND A LARGE NUMBER OF PJNK POSITIVE CELLS WERE HDAC2 POSITIVE. INTRATHECALLY INFUSION OF THE JNK INHIBITOR SP600125 SIGNIFICANTLY INHIBITED SNL-INDUCED UPREGULATION OF HDAC2. SNL-INDUCED HDAC2 UP-REGULATION COULD BE INHIBITED BY THE NEUTRALIZING ANTI-TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA) BINDING PROTEIN ETANERCEPT OR THE MICROGLIAL INHIBITOR MINOCYCLINE. IN CULTURED ASTROCYTES, TNF-ALPHA INDUCED ENHANCED PHOSPHORYLATION OF JNK AND A SIGNIFICANT INCREASE OF HDAC2, AS WELL AS A REMARKABLE DECREASE OF GLT-1, WHICH COULD BE PREVENTED BY SP600125 OR THE HDAC2 SPECIFIC INHIBITOR CAY10683. OUR DATA SUGGEST THAT ASTROCYTIC JNK-HDAC2 CASCADE CONTRIBUTES TO GLT-1 DECREASE AND MECHANICAL ALLODYNIA FOLLOWING PERIPHERAL NERVE INJURY. NEUROIMMUNE ACTIVATION AFTER PERIPHERAL NERVE INJURY COULD INDUCE EPIGENETIC MODIFICATION CHANGES IN ASTROCYTES AND CONTRIBUTE TO CHRONIC PAIN MAINTENANCE. 2021 4 2470 26 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 5 6148 23 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