The Survival Of Immune Cells From Peripheral Blood In Kidneys After Ischemia-reperfusion Injury:Lessons From The Mice Parabiosis Model

Background Acute renal injury（AKI）is a common clinical renal disease now,which can be life-threatening in severe cases.Most AKI will be likely to be a chronic disease,eventually lead to chronic kidney disease（CKD）and end-stage renal disease（ESRD）.One episode of acute renal injury（AKI）can cause long-term renal damage,which leads to renal chronic inflammation and fibrosis,and finally contributes to CKD.After the AKI,the kidney innate immune cell and peripheral infiltrated immune cells can lead to structural and functional changes of renal units and renal fibrosis through a series of activation and recruitment reactions.T-lymphocytes,B-lymphocytes,neutrophils,dendritic cells and monocytes / macrophages participate in and regulate the process of renal inflammatory response,tissue’s reconstruction and repair.In the past researches,it has been confirmed that the immune cells in kidney which from peripheral immune cells play a key role in the progress AKI to CKD.However,there is still a lack of knowledge about the dynamic changes and the survival status of peripheral immune cells after migrating to the kidney.Based on this,we use the animal model of parabiosis and separation to track the peripheral immune cells and observe their survival regularity and changes at different phase of AKI to CKD after entering the injured kidney.Methods and Results In the first part,we improve the parabiosis model,enhance the survival rate of the parabiosis model,and build the parabiosis and separation model to achieve the purpose of long-term tracking of peripheral immune cells.First of all,we constructed a parabiosis model of GFP mice and C57 mice by surgical operation.After four weeks of surgical operation,we carried on IRI（renal ischemia-reperfusion）to cause acute renal damage.Then,we made two mice separate by operation,and killed the mice after a period of time.We collected samples,and used flow cytometry to detect chimeric changes of immune cells in mice.By observing the survival of the operation and detecting the chimerism rate of the mice,the model construction of the model was successfully built.In the second part,we divided the mice into four groups: parabiosis,parabiosis +IRI,parabiosis +separation,parabiosis +IRI +separation.Flow cytometry was used to detect the chimeric rate of peripheral immune cells in C57 mouse which from GFP mouse.The results showed that the chimerism rate of immune cells in peripheral blood of parabiosis was 50% on average.After 14 days of separation,the chimerism rate of different immune cells was different in peripheral blood and kidney.The results showed that the survival time and changes of different types of immune cells were also different after renal injury,which suggested that we can take more targeted and specific interventions for the immune cells during the treatment of progressive kidney disease.Conclusion 1.The model of parabiosis and separation can successfully track allogeneic cells for a long time and observe their survival and prognosis.2.The normal proportion of resident kidney immune cells was not affected by the operation of parabiosis and separation.Both F4 / 80^hi and F4 / 80^low macrophages in normal or injured kidneys have the source of supplement from peripheral monocytes.3.In the process of AKI,the survival time of peripheral T-lymphocytes is long,especially of CD4⁺ T-lymphocytes.4.The microenvironment of renal injury can prolong the survival time of macrophages from peripheral sources.