DECIPHER ROLE OF CLASS-1 HDACS ON P-GP EXPRESSION IN BRONCHIAL ASTHMA

Abstract

Background ¯ Glucocorticoid GCs are one of the most common reliable therapy · Over expression of P¯glycoprotein might be responsible for glucocorticoid resistance due to their ability to modulate the pharmacokinetics of glucocorticoids · Activated glucocorticoid receptors interact with co¯repressor molecules to impair NFkaphaB¯associated co¯activator activity´ which reduces histone acetylation ´ chromatin remodeling · Reduction in histone acetylation occurs through the recruitment of histone deacetylase HDAC 2 to the activated inflammatory gene complex by activated glucocorticoid receptor ´ resulting in efficacious suppression of activated inflammatory genes within the nucleus ·

Methods¯ The Bronchial Asthma BA patients were categorized in 3 groups ¦ Group1¦ Steroid responsive BA in Remission Group n¨33 Group 2¦ Steroid resistant BA n¨19¦ Group 3 Healthy control n¨10 Peripheral Blood Mononuclear Cells PBMCs were isolated from human blood · Before short¯term culture 24hr culture ´ PBMCs were treated with 1µM of Theophylline and 0·8µM of Trichostatin A for a period of 48 hours· RNA was extracted from PBMCs using RNA iso Plus ·Total of 1µg of RNA processed for cDNA synthesis using cDNA Synthesis Kit as per the manufacturer protocol ·We performed real¯time PCR reactions for each cDNA sample in triplicate using LightCycler& and174; 480 SYBR Green I Master and gene specific primer pairs for HDAC2´ P¯gp and GAPDH ·

Results¯ Between the groups demographically differed in age of onset of the disease SSBA¨5·26±2·46, SRBA¨9·86±5·39´ HC¨4·16±2·36 p¨0·005 and biochemical differences were seen in serum esinophils SSBA¨1·65±·293´SRBA¨3·65±1·689´HC¨4·09±1·46 p¨<·011·mRNA level of P¯gp was up regulated (p<0·05 compare with steroid sensitive and Healthy control whereas HDAC2 mRNA level was down regulated· p<0·05 in SRBA compared to that SSBA· Percentage viability for Theophylline at 1µM and of TSA at 0·8µM was found to be 81 percent · Treatment with Theophylline¯1µM reduced mRNA expression of P¯gp in SSBA and HC but not upto the levels of SRBA· Trichostatin¯ A¯0·8 µM treatment in SSBA patients upregulated expression level of P¯gp but not in consistence with SRBA patients·

Conclusion¯The changes of HDAC2 expressions significantly regulate the expression of P¯glycoprotein and introduction of HDAC2 stimulator may reverse steroid resistance·