| Psoroptic ear mange is a chronic invasive parasitic disease caused by Psoroptes ovis var.cuniculi,which is an ectoparasite living on the skin surface of the rabbit ear canal.Psoroptic ear mange spreads rapidly in rabbits,and the incidence is even higher in cloudy and humid seasons,up to 70%.Psoroptic mange causes the reducing in growth rate and product quality,and even cause death if it is untreated.This disease exerts large economical lose impacts on the rabbit industry.For a long time,the prevention and treatment of psoroptic mange are based mainly on the use of effective acaricides.but in view of the emergence of drug resistant strains and drug residues in animal products,which would be potential impacts on human health and other issues,there is an urgent need to develop alternative treatments for P.ovis infection.A better understanding of the mechanisms of this disease is the foundation of seeking new prevention measures.However,research on the pathogenic mechanism of the P.ovis infection is thus far very limited.Therefore,our present study investigated the histopathological difference between skin lesions in rabbits with different degrees of infection by P.ovis,and detected the expression of cytokine factors IFN-y/IL-4 and transcription factors T-bet/GATA-3 in the lesions of psoroptic ear mange,then furtherly analyzed the trend of reaction of Thl/Th2 immune response in the psoroptic ear mange,so as to lay a preliminary basis for the pathogenic mechanism of psoroptic mange.And the main results are summarized as follows:1.Comparative pathology of different skin lesion scores of psoroptic mange in rabbits.In order to compare the histopathological difference of different skin lesion scores of psoroptic mange in rabbits,the diseased groups of twenty New Zealand White rabbits with different lesion scores,artificially infected with Psoroptes ovis var.cuniculi(score 1 group,score 3 group and score 5 group:five rabbits respectively)and five clinically healthy control rabbits(score 0 group)were evaluated.The ear skin samples were obtained from infected rabbits and healthy rabbits with disposable annular sampler.The hematoxylin-eosin staining and toluidine blue staining of ear skin samples were used to examine,and the histopathological difference under the microscope and eosinophils and the mast cells were counted in ear skin tissue.There was no significant difference in the histopathology of the epidermis of the diseased groups(score 1 group,score 3 group and score 5 group),and pathologic evaluation of the lesions in epidermal layer were mainly the hyperplasia of stratum spinosum.In the superficial dermis of ear skin lesions,we observed a cell infiltration including eosinophils,lymphocytes,macrophages,and plasma cells and accompanied by mast cell hyperplasia.There was significantly increased of eosinophils in score 1,3 and 5 groups(score 1 group:716 ± 255 cells/mm2,P<0.05;score 3 group:1127± 320 cells/mm2,P<0.01;score 5 group:876 ± 349 cells/mm2,P<0.05)versus score 0 group(0 cells/mm2).The mast cells in score 1,3 and 5 groups appeared to be more in number than score 0 group,but the difference was not significant(P>0.05).The findings in this study revealed that P.ovis caused a hyperplastic lesions in parasitic site,and provoked a skin inflammatory reaction with dense eosinophilic infiltration and mast cell hyperplasia.This inflammatory response would furtherly aggravate the damage of the host skin to develop higher lesion scores caused by P.ovis.2.Expression of characteristic cytokines and transcription factors of Thl/Th2 immune response to different skin lesion scores of psoroptic mange in rabbits.The purpose of this study was to investigate the expression of cytokine factors IFN-y/IL-4 and transcription factors T-bet/GATA-3 in psoroptic ear mange with different lesion scores and Thl/Th2 immune response to psoroptic ear mange.The diseased groups of New Zealand White rabbits with different lesion scores,artificially infected with Psoroptes ovis var.cuniculi(score 1 group,score 3 group and score 5 group:five rabbits respectively)and five clinically healthy control rabbits(score 0 group)were evaluated.The ear skin samples were obtained from infected rabbits and healthy rabbits with disposable annular sampler.The expression of IFN-?/IL-4 and T-bet/GATA-3 in ear skin samples were investigated by immunohistochemical technique,enzyme-linked immuno sorbent assay(ELISA)and fluorogenic quantitative PCR.Compared to the score 0 group(0.3442 ±0.01433pg/mg),the level of IFN-y protein in the skin lesions increased in diseased groups(score 1,3 and 5 groups),but only score 3 group was showing significantly increased(0.4636 ± 0.014948pg/mg,P<0.05).Meanwhile,the level of IFN-? mRNA in skin lesion also significantly increased in score 3 group(P<0.05).There was a slightly increase in the level of IL-4 protein in score 1 group(0.1488 ± 0.01426pg/mg)versus score 0 group(0.135 ± 0.003633pg/mg),however,there was no significant difference between score 0 group and score 1 group(P>0.05).The similar statistical difference on the level of IL-4 mRNA was found between score 1,3 groups and score 0 group(P>0.05).The positive products of two transcription factors T-bet and GATA-3 were both located in the nucleus,and no significant difference was investigated between diseased groups(score 1,3 and 5 groups)and healthy group(score 0 group)(P>0.05).The level of T-bet mRNA were higher in diseased groups(score 1,3 and 5 groups)than healthy group(score 0 group),but there were significantly increased in score 1 and 3 groups(P<0.05).The level of GATA-3 mRNA in diseased groups(score 1,3 and 5 groups)decreased in comparison with score 0 group,and there was significantly reducing in score 3 and 5 groups(P<0.05).Our findings indicated the Th2 immune response of host was inhibited,and the Thl immune response became stronger as the skin lesion scores increases in rabbits with the decrease of GATA-3 and the increase of IFN-? and T-bet. |
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