| Osteoarthritis(OA)is a chronic joint degenerative disease characterized by degeneration of articular cartilage.It often causes joint pain and even disability.It seriously affects the quality of life of the patients and brings great economic burden to the society and family.In the study of OA etiology,the relationship between OA and metabolic syndrome(MS)has attracted more and more attention.More and more scholars believe that OA belongs to the MS category.Barker,a British scholar,based on the results of a large-scale epidemiological survey,found that the incidence of MS in children with intrauterine growth retardation(IUGR)was increased and the hypothesis of "the origin of adult disease development" was proposed.Although the research reports on the correlation between OA and MS,MS and IUGR are increasing rapidly,there is little research on the direct connection between OA and IUGR.An epidemiological study showed that the proportion of OA in the hands of men with low birth weight was significantly higher than that of the control group,and there was a similar trend among women.It is suggested that OA has the same fetal origin as MS.Articular cartilage is the main organization of pathological changes in OA,and its quality is closely related to the pathogenesis of OA.Studies have suggested that the quality of articular cartilage is correlated with the occurrence of OA.Articular cartilage is mainly formed in the embryonic period.Dysplasia of the articular cartilage in the uterus may be one of the important reasons for the susceptibility of adult OA.Studies have shown that cartilage cholesterol metabolism is abnormal,and the accumulation of cartilage cholesterol is closely related to the occurrence of adult OA.It is suggested that the mechanism of fetal OA also includes cholesterol accumulation in articular cartilage.It is known that normal chondrocytes are mainly composed of extracellular matrix by secreting proteoglycan(aggrecan)and type II collagen(Col II)to maintain the physiological function of articular cartilage.Transforming growth factor-beta(TGF beta)signaling pathway plays an important role in the development and differentiation of chondrocytes.TGF beta-Smad2/3 is a key pathway for the initiation of gene transcription in cartilage matrix,and is important for the development of articular cartilage.Studies have shown that cartilage cholesterol outflow pathway dysfunction also participates in the occurrence of cholesterol accumulation in adult OA cartilage.The TGF beta signaling pathway also promotes the expression of cholesterol efflux related genes.Epidemiological studies have shown that nicotine intake is not conducive to the health of the individual itself,and the risk of cartilage loss and pain in smokers with osteoarthritis is much higher than that of non smoking patients.Animal experiments also showed that when exposed to nicotine stimulation in rats,the inflammatory reaction was more obvious and the joint injury was more serious.An epidemiological study suggests that maternal smoking during pregnancy significantly increases the risk of abnormal development of the musculoskeletal system of the offspring,and suggests that prenatal nicotine exposure(PNE)during pregnancy is one of the exact and dangerous causes of IUGR.A series of previous studies in our laboratory confirmed that PNE could weaken the placental glucocorticoid(glucocorticoids,GC)barrier and cause the fetal "maternal GC" to increase the susceptibility to MS in the adulthood of IUGR fetus,and there is a "neuroendocrine metabolic programming mechanism".The laboratory also found that PNE can cause the growth plate of fetal mice.The mechanism of bone development retardation may be related to high maternal GC.A large number of studies have confirmed that there is a close relationship between maternal high GC during pregnancy and intrauterine programming changes in offspring.It is also found that high GC during pregnancy can inhibit the longitudinal growth of fetal bone,which can lead to the decrease of chondrocyte proliferation,the decrease of matrix synthesis,the thinning of articular cartilage and the decrease of the content of the ECM.The mechanism may be that high GC inhibits the proliferation of fetal chondrocytes and its TGF beta signaling pathway,and the cell growth and its TGF beta signaling pathway;and cell It was proved that excessive GC level could inhibit the expression of TGF beta R in cells.In view of the above,can PNE increase the susceptibility to OA after birth by means of "maternal high GC"?The mechanism may be related to the TGF beta signaling pathway and the programming of cholesterol efflux pathway.Does the low programming changes in the cholesterol outflow pathway of PNE offspring increase the susceptibility of OA?None of these questions have been found in the relevant literature.To this end,the following work is to be done:using PNE induced IUGR model and intravasal papain injection of OA model to confirm the accumulation of cholesterol and OA susceptibility to PNE induced offspring cartilage,and further observe the changes of TGF beta signaling pathway and cholesterol efflux pathway in the PNE progeny,and explore the OA susceptibility of PNE progeny.The mechanism of intrauterine programming and the mechanism of cholesterol accumulation in the offspring of PNE were explored by giving birth control lipid-lowering pravastatin to the offspring of OA.The implementation of this project will help us to understand the OA susceptibility and intrauterine programming mechanism of the PNE progeny more comprehensively,better understand the fetal OA,and to further explore the early prevention and treatment of OA.PART ONEPrenatal nicotine exposure can lead to the accumulation of cholesterol in the articular cartilage of male rats and the susceptibility to osteoarthritis.Objective:This part of the study is to use PNE induced IUGR rat model and injection of papain into the knee joint to induce OA model,and to observe whether PNE can cause the cartilage dysplasia of the adult IUGR offspring,and the accumulation of cartilage cholesterol and the increase of susceptibility to OA.Methods:Intrauterine:Wistar rats were randomly divided into control group and nicotine group after natural conception.From GD9 to GD20,the nicotine group was given nicotine 2mg/kg.d subcutaneously,while the control group was given equal volume distilled water.After birth:the PNE group was randomly left to get some pregnant rats to make natural production.The offspring were born 12 weeks after birth(postnatal week,PW12),and were killed by ether anesthesia,and the knee joint was taken.OA model:the male offspring of PNE male rats(2mg/kg.d)and the control group were given normal diet to 8 weeks of age after weaning,and the OA model[80]was made by injection of papain in the knee joint in PW8.The control group and the PNE group were injected with 4%papain in the left knee joint of the first,fourth,seventh,10 and 13 days respectively.The solution was 100 L;the right knee was injected with the same amount of normal saline at the above time point.In PW12,rats were killed by ether anesthesia and the knee joints of lower extremities were taken.Results:?Compared with the control group,the total morphology of the articular cartilage in the PNE group was less than that of the control group when the papain was not stimulated by the adult rats.After the stimulation of papain,the articular cartilage of group PNE was stained with the naked eye,the cartilage surface was seriously worn,the surface of the articular soft bone lost the gloss and roughness;?in the PNE group can see cartilage cartilage surface ink especially tibia articular cartilage surface wear lose luster,rough treatment with papain stimulation;?papain after Safranine O-solid green staining showed stimulation compared with the control group,PNE group appeared on the worn surface of cartilage,cartilage matrix structural disorder,cartilage thickness,matrix superficialdyeing,cartilage cells significantly decreased,the tide line blurred,and a group of modified Mankin scores increased more significantly than the control group(P<0.01);?treatment group and papain after stimulation,compared with the control group,simple group Xiansheng cartilage high total cholesterol levels(P<0.01),and the expression of Col2al and aggrecan mRNA Significantly decreased significantly(P<0.01);compared with the control group,after different degree of cartilage safranin O staining intensity of PNE group and intrauterine birth offspring cartilage at different time points,type II collagen immunohistochemical staining of mRNA and Col2al gene,synthesis of cartilage matrix proteoglycan expression decreased(P<0.01).Conclusion:PNE can cause hypoplasia of the articular cartilage of the offspring,and the accumulation of cholesterol in the cartilage is more likely to lead to the occurrence of O A after the injection of papain into the knee joint.PART TWOEffect of prenatal nicotine exprosure induced osteoarthritis in male rats during pregnancyObjective:This part is to observe the expression of TGF beta signaling pathway and cholesterol efflux pathway in the PNE offspring rats during the intrauterine period by the whole animal experiment,in order to explore the intrauterine programming mechanism of the cholesterol accumulation of adult cartilage and the susceptibility to OA in the offspring of PNE induced offspring.Methods:Intrauterine:Wistar female mice are naturally pregnant.From GD9 to GD20,nicotine 2mg/kg.d was injected subcutaneously,while the control group was given equal volume distilled water.At GD20,the pregnant rats were anesthetized with ether and the fetuses were removed from the abdominal cavity.The number of fetuses per litter was 8-14 rats and their fetuses.The weight and sex of fetal rats were recorded and the knee joint tissues of male rats were taken.Results:?Compared with the control group,the expression of Col2al and Aggrecan mRNA and protein in articular cartilage of PNE group was significantly decreased(P<0.01);?The expression of TGF beta signaling pathway in cartilage:compared with the control group,the expression of mRNA and protein of TGF beta RI,Smad2 and Sox9 in the cartilage of the PNE group decreased significantly(P<0.01).;?the expression of cholesterol efflux pathways:cartilage cells in the uterus after birth and decreased in different degree,the expression of mRNA and LXR gene protein group at different time points of the(P<0.01),and SR-B1,ABCA1 mRNA are also different decreased(P<0.01).Conclusion:We found that intrauterine PNE may lead to low functional programming of the progeny cartilage TGF beta signaling pathway and cholesterol efflux pathway through maternal GC,which may lead to offspring cartilage dysplasia and cholesterol accumulation.PART THREEPervastatin can improve nicotine exposure during pregnancy to induce the accumulation of cholesterol in the articular cartilage and the susceptibility to osteoarthritis of the male ratsObjective:In this part,the lipid lowering drug pravastatin was given through the whole animal experiment to observe the cartilage mass,the cholesterol efflux pathway and the expression of OA in the offspring,and to explore the possible causes and mechanisms.Methods:Wistar rats were randomly divided into control group and PNE group after conception.From GD9 to GD20,2 mg/kg.d of nicotine was injected subcutaneously,while the control group was given equal volume distilled water.After natural production of pregnant mice,PNE male offspring were given normal diet to 8 weeks of age.At PW8,pravastatin(20mg/kg.d)or equal volume of saline was injected subcutaneously to PW12.During the period of the group,papain was injected into the joint cavity for the injection of papain OA.That is to say,the rats in the control group and PNE group were randomly divided into control + saline group,control + pravastatin group,PNE+ saline group and PNE+ pravastatin group.In PW12,rats were sacrificed by ether anesthesia and bilateral lower limb knees were collected.Results:? After the stimulation of papain,compared with the PNE+ saline group,the cartilage surface of the articular cartilage in the PNE+ pravastatin group appeared to be significantly reduced in the visible surface of the cartilage surface,especially on the tibial plateau cartilage surface;? In the normal saline group,the mRNA expression of LXRa,SR-B1 and ABCA1 in the PNE group was significantly lower than that in the control group(P<0.01),and the expression of Col2al and Aggrecan mRNA in the PNE group was significantly lower than that of the control group(P<0.01).Decreased(P<0.01),while Col2al and Aggrecan in group PNE also decreased significantly(P<0.01).?At PW12,compared with PNE+ saline group,the expression of cartilage inflammation and matrix degradation index of IL-1,IL-6,MMP-3 and MMP-13 in PNE+ pravastatin group decreased significantly(P<0.01),and the expression of cartilage cholesterol accumulating index LDL,oxLDL,LOX-1 was also significantly decreased(P<0.01).Conclusion:Statins can improve the inhibition of cholesterol efflux pathway in cartilage of adult offspring rats induced by PNE,thereby reducing cartilage cholesterol accumulation and alleviating OA susceptibility. |
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