| Background:Systemic lupus erythematosus(SLE)is an autoimmune diseases,diffuse to the T and B cell activation,a large number of antibodies and immune complex(immune complex,IC)formation and many tissues and organs damaged as the main characteristics,,see more at childbearing age women.At present,it is believed that many mechanisms,such as genetic and environment are involved in the occurrence and development of SLE.Abnormal activation of innate immune cells,such as mononuclear macrophages,Dendritic cells(DC)and natural killer cells(NK),is widely involved in the destruction of immune homeostasis in SLE.Inherent immunity can eliminate foreign pathogens by activating adaptive immune response,thus it is also known as the first immune barrier of the human body.It can eliminate foreign pathogens through pattern recognition receptor.PRR(pathogen associated molecular pattern(PAMP))plays a role.Inflammatory bodies can be formed after activation of nucleotide binding oligome-rization domain-like receptors(NLRs).By activating cysteinyl aspartate-specific proteinase(caspase-1),inflammasomes promote the downstream cytokine interleukin-1 beta(interleukin-1beta).IL-1β(IL-1β)and interleukin-18(IL-18)are involved in the regulation of inflammation and immune response.NLRP3 inflammasome is composed of NLRP3,ASC and procaspase-1 via the PYD-CARD domain.It has been shown that NLRP3 inflammasome plays an important role in the occurrence and development of SLE and renal damage in lupus.Our previous research group show:Low expression of NLRP3 inflammasome in peripheral blood mononuclear cells(PBMCs)in patients with SLE increases after hormone therapy and is negatively correlated with SLE disease activity.Therefore,it is considered that NLRP3 possibly play a protective role in the immune pathogenesis of SLE,which is inconsistent with the classical activation pathway of NLRP3 inflammasome,and it is speculated that there may be non-classical activation pathway of NLRP3 inflammasome involved in the pathogenesis of SLE.Interferon(IFN)is a kind of cytokine,which plays a variety of roles such as antiviral and immune regulation,and is widely involved in the body’s immune response and immune regulation.Interferon activates non-receptor tyrosine protein Kinase JAK(Janus Kinase)and regulates gene transcription through the JAK-STAT signaling pathway to further regulate the immune response.The physicochemical properties and biological characteristics of the interferon family are different,and they are further divided into three types:Ⅰ,Ⅱ and Ⅲ.Among them,type Ⅰ interferon is an important effector molecule involved in antiviral immunity.Previous studies have found that type Ⅰ interferon is generally highly expressed in SLE patients and lupus mouse models,and is closely related to disease activities.Current studies have found that the activation conditions of NLRP3 inflammasome are extensive,and there are multiple pathways involved,toxins,bacteria,foreign body crystallization,Ion pathway anomaly and so on can stimulate the activation of NLRP3 inflammasome.However,there are few studies on the negative regulation mechanism of NLRP3 inflammasome.Some studies have found that type Ⅰ interferon has a negative regulation mechanism of NLRP3 inflammasome,but there are still many debates about this.In this study,the mRNA expression levels of IFN-α,IFN-β and NLRP3 inflammasome in MRL/lpr lupus mice were detected,and the correlation between IFN-α,IFN-β and NLRP3 inflammasome in MRL/lpr lupus mice and the titer of anti-ds-DNA antibody and the level of urinary protein were analyzed,so as to explore the correlation between IFN type Ⅰ and NLRP3 inflammasome in the incidence of SLE.To explore the mechanism of negative regulation of NLRP3 inflammasome by type Ⅰ interferon.Objective:To investigate the abnormal expression of type Ⅰ IFN and NLRP3 inflammasome in MRL/lpr lupus mice and the possible mechanism of negative regulation of NLRP3 inflammasome by type Ⅰ interferon.Methods:9-week-old MRL/lpr mice and wild-type C57BL/6 mice were selected as the research subjects.MRL/lpr mice were further divided into MRL/lpr mouse group,MRL/lpr+prednisone(2.5 mg/kg)group and MRL/lpr+prednisone(5 mg/kg)group.Wild type C57BL/6 mice were used as healthy control group.Six in each group.Different doses of prednisone acetate or normal saline were given for intervention.The joint swelling and nerve involvement of mice were observed during the continuous intervention for 9 weeks.Peripheral blood,urine and renal tissues of each group were collected after the intervention for subsequent studies).Urinary protein concentration of mice was determined by CBB method.Enzyme-linked immunesorbent assay(ELISA)was used to determine the titer of anti_ds-DNA antibody in serum.The mRNA expression levels of NLRP3,ASC,Caspase-1,IFN-αand IFN-β in renal tissues were detected by Real-time PCR.To analyze the changes of the expression levels of these indexes before and after different doses of prednisone intervention and to explore their correlation.Results:1.Compared with the healthy control group,the titer of anti-ds-DNA antibody in serum of MRL/lpr group was higher than that of healthy control group(P<0.001),MRL/lpr+prednisone(2.5mg/kg)group and MRL/lpr+prednisone(5mg/kg)group significantly reduced serum anti-ds-DNA antibody titers in MRL/lpr lupus mice(P<0.01;0.001),serum anti-ds-DNA antibody titer decreased more significantly in MRL/lpr+prednisone(5mg/kg)group than in MRL/lpr+prednisone(2.5mg/kg)group(P=0.023).2.Compared with the healthy control group,the urine protein concentration in the MRL/lpr group was higher than that in the healthy control group(P<0.001);MRL/lpr+prednisone(2.5mg/kg)group and MRL/lpr+prednisone(5mg/kg)group significantly reduced the concentration of urine protein in MRL/lpr lupus mice(P<0.001;P=0.002),the decrease of urine protein concentration in MRL/lpr+prednisone(2.5mg/kg)group was more obvious than that in MRL/lpr+prednisone(5mg/kg)group,but there was no statistical difference(P=0.340).3.Compared with the healthy control group,the mRNA expression of NLRP3 and ASC in the renal tissue of mice in the MRL/lpr group were lower(P<0.001;P=0.001),while caspase-1 mRNA was highly expressed(P=0.009).After prednisone intervention,the mRNA expression of NLRP3 in MRL/lpr lupus mice increased,but there was no statistical difference(P=0.930;P=0.141),the increase of NLRP3mRNA expression in MRL/lpr+prednisone(5 mg/kg)group was more obvious than that in MRL/lpr+prednisone(2.5 mg/kg)group,but there was no statistical difference(P=0.146).ASCmRNA expression decreased,but there was no statistical difference(P=0.732;P=0.129),ASC mRNA expression decreased more obviously in MRL/lpr+prednisone(5mg/kg)group than in MRL/lpr+prednisone(2.5mg/kg)group,but there was no statistical difference(P=0.205);The expression of caspase-1 mRNA decreased,and there was a statistical difference between the MRL/lpr+prednisone(5mg/kg)group and the MRL/lpr prednisone group(P=0.021).There was no statistical difference between the MRL/lpr+prednisone(2.5mg/kg)group and the MRL/lpr+prednisone group(P=0.721).The expression of caspase-1 mRNA decreased more obviously in the MRL/lpr+prednisone(5mg/kg)group than in the MRL/lpr+prednisone(2.5mg/kg)group(P=0.035).4.Compared with healthy control group,the mRNA expression of IFN-α and IFN-β in MRL/lpr group was higher(P<0.01;0.001);Compared with MRL/lpr group,the mRNA expressions of IFN-α and IFN-β in MRL/lpr+prednisone(2.5mg/kg)group were significantly decreased after prednisone intervention(P=0.002,P<0.001);After prednisone intervention,the mRNA expressions of IFN-α and IFN-β in MRL/lpr+prednisone(5mg/kg)group were significantly decreased(P<0.001,P=0.001).The mRNA expression levels of IFN-α and IFN-β in MRL/lpr+prednisone(5 mg/kg)group decreased more significantly than that in MRL/lpr+prednisone(2.5 mg/kg)group(P=0.007,P=0.086).5.There was a negative correlation between NLRP3 mRNA expression and caspase-1 mRNA expression in renal tissues of MRL/lpr lupus mice(r=-0.561,P=0.024).There was a positive correlation between ASC mRNA expression and caspase-1 mRNA expression in renal tissues of MRL/lpr lupus mice(r=0.852,P<0.001);There was no correlation between NLRP3 mRNA expression and ASC mRNA expression in renal tissues of MRL/lpr lupus mice(r=0.289,P=0.278).6.NLRP3 mRNA expression was negatively correlated with IFN-α and IFN-βmRNA expression in renal tissues of MRL/lpr lupus mice(r=-0.609,P=0.012;r=-0.795,P<0.001);The mRNA expression of ASC was not correlated with the mRNA expression of IFN-α and IFN-β(r=0.278,P=0.297;r=0.238,P=0.375).The mRNA expression of caspase-1 was not correlated with the mRNA expression of IFN-α and IFN-β(r=0.486,P=0.056;r=0.465,P=0.070).7.NLRP3 mRNA expression in renal tissues of MRL/lpr lupus mice was negatively correlated with serum ds-DNA antibody titer(r=-0.753,P=0.001).There was no correlation with urinary protein concentration(r=0.387,P=0.138).There was no correlation between ASC mRNA expression and serum anti-ds-DNA antibody titer and urine protein concentration(r=0.3 16,P=0.233;r=0.300,P=0.260).Caspase-1mRNA expression was positively correlated with serum ds-DNA antibody titer(r=0.647,P=0.028).There was no correlation with urinary protein concentration(r=0.435,P=0.092).8.IFN-α mRNA expression in renal tissues of MRL/lpr lupus mice was positively correlated with serum anti-ds-DNA antibody titer(r=0.700,P=0.003).There was no correlation with urinary protein concentration(r=0.393,P=0.132).The expression level of IFN-βmRNA was positively correlated with the titer of serum anti-ds-DNA antibody and the concentration of urinary protein(r=0.785,P<0.001;r=0.700,P=0.003).Conclusions:1.Low expression of NLRP3 was found in renal tissues of MRL/lpr lupus mice,and the low expression of NLRP3 was negatively correlated with the titer of anti-ds-DNA antibody.2.The high expression of Caspase-1 in the renal tissues of MRL/lpr lupus mice was positively correlated with the tits of anti-ds-DNA antibody,suggesting that Caspase-1 was correlated with the incidence of SLE and LN,and was positively correlated with disease activity.3.Type Ⅰ interferons(IFN-α,IFN-β)were highly expressed in the renal tissues of MRL/lpr lupus mice,and were closely related to the disease activity of SLE,suggesting that they may be involved in the pathogenesis of SLE and LN4.NLRP3 was negatively correlated with the expression of IFN-α and IFN-β in the renal tissues of MRL/lpr lupus mice,suggesting that type Ⅰ interferon may negatively regulate NLRP3 in the pathogenesis of SLE. |
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