Elder Blood Accelerate Bone Loss Of Young Mice Through CCL11

Background: Aging,a systemic event,affects not only an organization or organs in an isolated way,but also has an adverse effect on the skeletal system.Osteoporosis(OP)is a systemic disease,which leads the reduction in bone mass,the bone structure destruction,an increase in bone brittleness and therefore be prone to fracture.Primary osteoporosis includes postmenopausal osteoporosis,senile osteoporosis and idiopathic osteoporosis.Osteoporosis relative to aging mainly refers to senile osteoporosis.Because anti-aging treatment can increase the amount of bone trabecula in mice and bone biomechanical characteristics,we have reasons to believe that anti-aging is an effective way to treat senile osteoporosis.For a long time,people have been studying the anti-aging and expecting to obtain living forever.Blood,plasma and their derivatives can promote the function of stem cells and tissue regeneration and repair,so they could fight the aging process.It is very important to realize the blood exchange of two animal individuals through parabiosis or plasma injection for the researches of aging or anti-aging.Some studies have shown that the adverse effects of aging can be prevented by heterochronic parabiosis or young plasma injection,which has a positive effect on the treatment of osteoporosis in elderly animals.On the other hand,heterochronic parabiosis or old plasma injection can adversely affect the tissue of young animals.Objective: we speculated whether there was certain or some key factor in animal's blood,which changed with aging and influenced the genesis and development of osteoporosis.The purpose of this study was to investigate whether the elderly plasma could affect the bone "aging" in rats,and to further study the key molecules and their significance to osteoporosis.Methods and Results:The research contains three parts:In the first part,the impact heterochronic parabiosis or old plasma injection had on the young mice bone mass was observed.There were three groups: namely the parabiosis group between young mice and young mice;the parabiosis group between young mice and old mice;non-effective parabiosis group.After four weeks parabiosis was established,we injected Evan dye liquor in one mice,observed its movement from the mice to another mice and established whether the parabiosis model was successful.After three mouths the parabiosis was successfully established,we observed the bone mass loss in those models.We found the young mice of the parabiosis group between young mice and old mice was significantly lower than other groups(the parabiosis group between young mice and young mice;non-effective parabiosis group)in BMD,BV/TV,Tb.N,Tb.area,N.ob/B.Pm and P1NP;While N.Oc/B.Pm,CTX was significantly higher than other groups.Plasma injection model contains three groups: namely injecting young plasma group,injecting old plasma group,injecting Saline group.Firstly,we extracted blood and collected plasma from 18 month and 3 month mice.Secondly,we injected 3 month mice tail vein using the plasma collected from 18 month mice or the plasma collected from 3 month mice respectively for 8 weeks,0.2 ml each time,twice weekly.In addition,we injected 3 month mice tail vein for 8 weeks using Saline,0.2 ml each time,twice weekly.After two month the plasma or Saline was injected,we found the young mice injected with 18 month plasma was significantly lower than the young mice injected with 3 month plasma and the young mice injected with saline in BMD,BV/TV,Tb.N,Tb.area,N.ob/B.Pm and P1NP;While N.Oc/B.Pm,CTX was significantly higher than other groups.Hence after the young mice was injected by old plasma or was connected with old mice by parabiosis,the bone mass loss of young mice was aggravated.In the second part we filtrated the key molecules that affect bone loss.Through the analysis of protein chip,the four possible key molecules that affect bone mass loss were selected preliminarily: namely CCL11,CXCL1,IL-13,CCL5.Further,we contrasted the bone mass loss of injecting old plasma and injecting old plasma and the respective antibody of the four molecules.We found the group injected with old plasma and CCL11 antibody was significantly higher than the group injected with old plasma in BMD,BV/TV,Tb.N,Tb.area while other group injected with old plasma and other antibody was no significant difference with the group injected with old plasma lonely.So,we suspect CCL11 was the key molecule.In the third part we studied the relationship between CCL11 and bone mass loss.We observed the relationship between CCL11 and bone mass loss and the experiment established three groups: namely control group(non-intervention),CCL11 injecting group,CCL11 and CCL11 antibody injecting group.For young mice and old mice the three groups was respectively established.We found,for young mice,CCL11 injecting group was significantly lower than the other two groups in BMD,BV/TV,Tb/N,Tb.area,N.ob/B.Pm and P1 NP while significantly higher in N.Oc/B.Pm,CTX.For old mice,CCL11 injecting group was significantly lower than the other two groups in BMD,BV/TV,Tb/N,Tb.area,N.ob/B.Pm and P1 NP while there was no significant difference among the three groups in N.Oc/B.Pm,CTX.Conclusion:1?For heterochronic parabiosis model,the bone mass of the young mice connected with old mice decreased;For plasma injecting model,the bone mass of the young mice injected with old plasma decreased.2?CCL11,CXCL1,IL-13,CCL5 were the common increasing molecules between heterochronic parabiosis and plasma injecting model.Among the four molecules,CCL11 was the key molecules that affected bone loss.3?CCL11 injection could result in bone mass loss of young and old mice and the effect vanished when CCL11 was restrained with CCL11 antibody.Therefore,administration of elder plasma can accelerate bone mass loss in young mice,and this phenomenon may be explained by the increasing of CCL11 in plasma of old mice.