Effects On Expression Of Retinoic Acid Receptors In Human Skin Keratinocytes By Tazarotene And Halometasone

Background and object:As we all known,the skin is the largest organ of the body.It possesses important physiological functions of barrier and absorption,secretion and excretion,temperature regulation,sensation,immune,respiratory and endocrine,and involves various activities and maintains homeostasis,which is critical for the health.Keratinocytes is a major component of the skin.They are not only closely related to the normal functioning of the epidermal barrier function,but also closely related to the pathophysiology of a variety of skin disorders.Nuclear receptors are the large class of intracellular receptors,which are widely distributed in the body and have an important regulatory function.so far,it has been found more than one hundred species of the nuclear receptor superfamily.As well known,the category of the nuclear receptor superfamily include many member,such as glucocorticoid receptors(GRs),retinoic acid receptors(RARs),retinoid X receptors(RXRs),vitamin D3 receptors(VDRs)and so on.Nuclear receptors are vital for the development and hosting the homeostasis,through recognizing and combining with relative response elements to regulating the transcription of the target genes.These receptors are riched in the epidermis.Many previous studies identified that nuclear hormone receptors play an important role in the skin for inhibiting the epidermal cell proliferation,regulating the differentiation of keratinocytes,promoting cell apoptosis and inflammation.Psoriasis is common chronic relapsing inflammatory skin disease of the main clinical manifestations as erythema and scales,and the pathology of epidermal cell proliferation,abnormal differentiation is considered as the main feature,but the etiology and pathogenesis is not entirely clear now.Topical administrations are the main treatment for mild to moderate psoriasis vulgaris.Topical steroid,retinoids,vitamin D3 derivatives and in combination with these drugs have been affirmed psoriasis treatment guidelines at home and abroad.As a member of the nuclear hormone receptor superfamily,glucocorticoid and retinoic acid exert their pharmacological effects to combining with their respective receptors.In view of that there may have existed a certain degree of interaction between the nuclear receptor superfamily.Is it a simple synergy therapeutic effect of both when glucocorticoid combined with tazarotene treatment for psoriasis? Whether glucocorticoid would have a therapeutic effect on the therapeutic effect of tazarotene? Whether tazarotene results in appearing the ligand-dependent receptor downregulation of keratinocytes? Regarding the issue above,we observed the expression of RAR-? and RXR-? on keratinocytes with different concentrations of tazarotene?Halometasone and tazarotene combining with halometasone to explore the possible impact of halometasone to tazarotene therapy for psoriasis,by studying the HaCaT cells and the highest amount of expression of epidermal RAR-? and RXR-? as the main index.Methods and results:1.Cell counting kit-8 was used to detect the cell proliferation of the immortalized human keratinocytes in vitro treated by different concentration of halometasone,tazarotene and halometasone association with tazarotene,which showed that the proliferation of the keratinocytes was decreased,and that with the increasing concentration of halometasone and tazarotene,the proliferation activity of keratinocytes was weaker.Meanwhile,the proliferation of keratinocytes treated with halometasone combination with tazarotene was stronger than that only with halometasone or with tazarotene.2.The expression level of mRNA of the retinoic acid receptor gamma and retinoid X receptor alpha was detected by Real-time polymerase chain reaction,which suggested that the expression mRNA of the retinoic acid receptor gamma with halometasone,retinoid X receptor alpha decreased after twelve hours,increased after twenty-four hours;and that the expressions of mRNA of the retinoic acid receptor gamma and retinoid X receptor alpha were decreased with tazarotene;but the expressions of mRNA of the retinoic acid receptor gamma and retinoid X receptor alpha were increased with halometasone combination with tazarotene after twelve hours,and decreased after twenty-four hours.3.The protein expression level of the retinoic acid receptor gamma and retinoid X receptor alpha was detected by the method of Western Blot assay,which revealed that the protein expressions of RAR-? and RXR-? were increased with halometasone.But the expressions of RAR-? and RXR-? were increased with tazarotene after 12 hours and reduced after 24 hours.Moreover,there was no significant difference of the protein expression of RAR-? and RXR-? of halometasone combination with tazarotene.Conclusion:1.Both tazarotene,a third-generation retinoids,and halometasone,a potent glucocorticoids possess the function of anti-proliferation of keratinocytes.Moreover,it is stronger of anti-proliferation effect with halometasone joint tazarotene than that alone tazarotene or alone halometasone.These datas provide an experimental basis for the treatment of halometasone conbination with tazarotene for vulgaris psoriasis.2.The expressions of RAR-? and RXR-? are down-regulated with tazarotene on the keratinocytes,which suggest that tazarotene may lead to the ligand-induced receptor downregulation in the short term.3.The expressions of RAR-? and RXR-? are up-regulated with halometasone on the keratinocytes.The effect of retinoic acid receptors up-regulation suggests that halometasone is able to enhance the effects of tazarotene on keratinocytes.4.There is no significant different in the protein expression of RAR-? and RXR-? with halometasone joint tazarotene,which provides experimental evidence for the feasibility of the combination of them.