The Effect And Mechanism Of Time-Restricted Eating On IMQ-Induced Psoriasis Mouse Model

Background:Psoriasis is a chronic inflammatory skin disease.Numerous studies have found that abnormal differentiation and activation of CD4+ T cells,especially T helper 17 cells(Th17),play a key role in the pathogenesis of psoriasis.Currently,biologics targeting Th17 have achieved good efficacy in psoriasis.However,psoriasis is an indolent disease that is prone to recurrence,and researchers have been seeking safe and effective preventive measures to better control its development.Some studies have found that obesity may be associated with inflammation and cellular senescence.The pathological state of inflammatory disease causes cellular senescence,and an abnormally high number of senescent cells can in turn alter the immune microenvironment of the disease and promote a further amplification of the inflammatory response.Previous studies have found an accumulation of senescent-like T cells in the lesions and circulation of patients with psoriasis.In clinical studies,weight loss such as calorie restricted diets or surgery have also been found to alleviate psoriasis.Time restricted eating(TRE)is a dietary intervention that limits daily eating to a window of time(e.g.8 hours).TRE reduces body fat percentage in obese individuals,promotes autophagy and extends the lifespan of fruit flies in experiments.Currently,most studies have only focused on the weight loss effects of TRE and its effects on metabolic diseases,with minimal research on the immune modulation of TRE and its therapeutic effects on psoriasis.Therefore,in this study,we propose to investigate the regulation of TRE on immune cell senescence and the reduction of clinical symptoms in mice with psoriasis.Objective:To investigate the effects of time-restricted eating(16:8)for 30 days on body weight and immune system in healthy subjects.To investigate the therapeutic effect of time-restricted feeding(16:8)on psoriasis mice model and its possible molecular mechanism.Methods:1.To investigate the effects of the TRE on body weight and immune system in healthy subjects.(1)A total of 64 healthy subjects were recruited to participate in the clinical trial(ChiCTR2200058137),49 in the TRE group and 15 in the Ramadan fasting(RF)group.subjects in the TRE group were asked to eat during the daily eating window of 9am-5pm and those in the RF group were asked to eat at night every day for 30 days in accordance with Ramadan.(2)Body weight was analysed and recorded to observe the weight loss effect of TRE and RF.(3)Multi-colour flow cytometry was used to explore the effects of TRE on each subpopulation of immune cells(CD3+T,CD4+T,CD8+T,Naive T,Memory T,Th1,Th2,Th17,Treg,Tfh-like,CD 19+B,Naive B,Memory B,PC cells)and senescence-like T cells in peripheral blood mononuclear cells(CD27-CD28-)frequency changes.(4)Immue repertoire sequencing of peripheral blood individual nuclei on day 0 and 30 of TRE to assess TCR and BCR abundance.2.To observe the therapeutic effect of TRF on IMQ-induced psoriasis mice model.(1)Eight-week-old Balb/c mice were randomly divided into time restricted feeding(TRF)and ad libitum(AL)groups,with a daily feeding window of 11pm-7am for 8 h.After 7 days of dietary intervention,imiquimod(IMQ)was applied to the backs of the mice to induce psoriasis-like skin lesions.Mice were executed after 7 days of continuous administration for analysis.(2)Daily body weights were measured and the severity of the lesions was assessed.(3)Flow cytometry was performed to detect the number and frequency of Th1,Th2,Th17 and Treg cells in the spleen of mice.(4)qPCR to detect the expression of senescence-related genes and inflammatory factors in CD4+T spleen cells.(5)Multispectral immunohistochemistry and qPCR to detect the expression of senescence-associated genes and inflammatory factors in skin lesions.RNA sequencing was used to further validate the differentially expressed genes in the two groups of skin lesions.Results:1.TRE/TRF demonstrated weight loss in healthy subjects and IMQ-induced psoriasis-like mice,while RF did not produce significant weight loss in healthy subjects.2.TRE had an effect on the immune system of healthy subjects:(1)TRE mainly affected the CD4+effector T cell subpopulation in healthy subjects,with a significant increase in Treg(CD127lo CD25hiCD4+)cell frequency(P<0.001),which returned to baseline levels 3 months after the end of TRE.(2)TRE sequentially significantly reduced the frequency of senescent-like T cells(CD4+CD27-CD28-)(P<0.001),which had not returned to baseline levels 3 months after the end of TRE.(3)Immune repertoire sequencing results showed an increase in the proportion of TCR α and β chains and a decrease in the proportion of BCR κ and λchains in subjects 30 days after the TRE intervention.TRE significantly reduced large clones of BCR-Heavy,κ and λ chains.3.TRF has therapeutic effects on IMQ-induced psoriasis mice:(1)TRF ameliorated skin lesion of IMQ-induced psoriasis mice(n=5,P=0.074),reduced the expression of senescence-related genes p21 and inflammatory factors at the lesions(n=7 in the AL group,n=5 in the TRF group,p21 P=0.0041,Il17a P=0.0429,I123α P=0.0336)and down-regulated inflammatory factor-related pathways(n=5).(2)TRF reduced the number of splenic Th2 and Th17 cells in IMQ-induced psoriasis mice and decreased the expression of senescence-associated gene p21 and inflammatory factors in CD4+T spleen cells(n=7 AL group,n=5 TRF group,p21 P=0.0114,1123α P=0.0444).Conclusions:(1)TRE improves the immune status of healthy subjects and clears large clones that appear due to pathological states such as infection,and these benefits are based on a normal circadian rhythm.(2)TRF has a therapeutic effect on psoriasis,probably by reducing senescent cells,regulating the balance of immune cell subsets(e.g.Th17)and reducing local inflammatory factor secretion in lesions.TRE is expected to be a new therapy for psoriasis.This thesis contains 34 graphs,13 tables and 80 references.