The Effect Of RhPTH(1-34) On Psoriasis-Like Mouse Model And Its Mechanisms

Objective Psoriasis is a chronic erythematous scaly skin disease characterized by hyperproliferation of epidermal keratinocytes and inflammatory cell infiltration caused by a combination of immune,genetic and environmental factors.The pathogenesis is not fully understood,and none of the available therapeutic drugs and therapies can cure completely.Recombinant human parathyroid hormone[rhPTH(1-34)]is the first 34 amino acid fragment of the N-terminal part of the PTH sequence,which is the biologically active part of PTH.The aim of this study was to evaluate the intervention effect of rhPTH(1-34)on psoriasis mouse model based on the successful construction of imiquimod-induced psoriasis mouse model,then screening of rhPTH(1-34)for differential transcription factors expressed by overexpressing epidermal growth factor receptor of keratinocytes,using transcriptome sequencing.To further investigate the possible mechanism of rhPTH(1-34)in the treatment of psoriasis,so as to lay the theoretical foundation for the treatment of psoriasis and related researches.Methods In this study,topical application of imiquimod cream on the back of B ALB/c mice was used to induce the production of psoriasis-like lesions in mice to successfully construct an animal model of psoriasis.Thirty-two BALB/c mice were randomly divided into four groups:control group,modeling group,low-dose rhPTH(1-34)group and high-dose rhPTH(1-34)group.The control group was injected intraperitoneally with 0.9%sodium chloride solution 0.1 mL.The remaining groups were injected intraperitoneally with 0.9%sodium chloride solution 0.1 mL and 0.6 mmol/L rhPTH(1-34)solution 0.1 mL,0.2 mL respectively,after applying imiquimod cream on the back.Psoriasis Area and Severity Index and blood calcium were measured.The morphological changes of the lesions were observed under microscopy,and the levels of interleukin(IL)-17 and tumor necrosis factor(TNF)-α in the lesions and serum were measured by ELISA.The intervention effect of rhPTH(1-34)on psoriasis mouse model was evaluated by the above indexes.Finally,lentiviral transfection of HaCaT cells was performed to overexpress EGFR and set up rhPTH(1-34)group and control group.0.01 μmol/L rhPTH(1-34)was added to the rhPTH(1-34)group,and equal volume of DMEM solution was added to the control group.Cellular RNA was extracted from both groups,and RNA yield and quality were examined by UV absorbance assay and denaturing agarose gel electrophoresis.The cDNA was synthesized and amplified by real-time quantitative PCR for accurate quantification of the effective concentration of the library.On-board sequencing was performed.Differences between the two sets of data were analyzed using DESeq2 software,and the sequencing results were analyzed to screen for differential transcription factors using |log2foldchange|≥1,P<0.05 as the screening condition.Results Compared with the control group,the mice in the modeling group showed erythema and scale on the back,and the PASI score was significantly higher,and the difference was statistically significant(P<0.05).Compared with the histopathology of the modeling group,the thickness of skin lesions in the low-dose and high-dose rhPTH(1-34)groups became thinner,and the difference was statistically significant(P<0.05).Compared with the modeling group,the expression of skin lesions and serum IL-17 were significantly lower in the low-dose and high-dose rhPTH(1-34)groups,and the difference was statistically significant(P<0.05);serum TNF-α was significantly lower in the low-dose group,and the difference was statistically significant(P<0.05).Compared with the control group,the blood calcium of the low-dose and high-dose rhPTH(1-34)groups did not change significantly,and the difference was not statistically significant(P>0.05);the blood calcium of mice in the modeling group was significantly increased,and the difference was statistically significant(P<0.05).A total of 185 genes were differentially expressed in the rhPTH(1-34)group compared with the control group,108 were up-regulated and 77 were down-regulated.Among the down-regulation,the five differential transcription factors with the highest |log2foldchange| were ZNF525,ZNF774,ZNF576,ZBTB42 and POU4F1(P<0.05).Among them,ZNF774 and POU4F1 were mainly involved in the regulation of Notch2 and MAPK signaling pathways,and the pathway are associated with the regulation of keratinocyte(KC)proliferation.Conclusion Intraperitoneal injection of rhPTH(1-34)alleviated psoriasis-like lesions in mice,inhibited IL-17 and TNF-α expression.rhPTH(1-34)inhibition of KC proliferation may be related to downregulation of ZNF525,ZNF774,ZNF576,ZBTB42,and POU4F1 expression.Among them,ZNF774 and POU4F1 may be associated with KC proliferation,which need to be explored further.