The Function And Mechanism Of Dipeptidyl Peptidase 4 In Pathogenesis Of Autosomal Dominant Polycystic Kidney Disease

ObjectiveAutosomal dominant polycystic kidney disease (Autosomal dominant polycystic kidney disease, ADPKD) is the highest incidence of human monogenic hereditary kidney disease. Substitution treatment of end stage renal disease (ESRD) in 7-10% of patients with ADPKD. Although the disease was found in 500 years we have done a lot of research, until today still no cure and its mechanism is not clear. All colors are not immune to ADPKD,7 ～10% of ESRD therefore the sky. Globally, the fourth leading cause of renal replacement therapy (RRT) is ADPKD. In different countries, ESRD incidence ADPKD result is different in Japan is 4.8 parts per million per year in the United States is 7.9 parts per million per year in Europe from 3.9 to 15.3 parts per million per year.Copenhagen, Denmark [4] and the United States of America Olmstead epidemiological investigation showed that the population under the age of 80, ADPKD prevalence is one of 1000 points to 400. Other studies since then in Europe and Japan show different regions ADPKD fluctuations in the prevalence of 4000 points to 543. In view of the above studies geography, observation time, sampling methods, diagnostic criteria, family investigation, has a different population size, and therefore, although large differences still understand. What, then, data from the autopsy report is higher than 1/500 of 1/339-1/492. This shows that a large number of patients with undiagnosed throughout their lives.ADPKD by the polycystic kidney disease gene 1 (Polycystic kidney disease 1 gene, PKD1) and polycystic kidney disease gene 2 (Polycystic kidney disease 2 gene, PKD2) caused by mutations in two genes, these two genes encode Polycystin -1 (Polycystin- 1, PC1) and polycystic protein -2 (polycystin-2, PC2). Wherein the patient PKD1 mutations account for 80 to 85% of patients PKD2 mutations account for 15 to 20%. The so-called PKD3, after re-analysis of relevant cases, has basically ruled out the possibility of its existence.PC1 and PC2 on renal tubular epithelial cells constitute the primary cilia interaction complex, which belongs to the transient receptor potential (transient receptor potential, TRP) family of a non-selective calcium channel penetration. PC1 C-terminal to the translocation domain can be the nucleus of the structure, and acts as a transcriptional co-activator. PC1 and PC2 cilia raised when subjected to mechanical stimulation of Ca2+ in the instant flow.Pathogenesis of ADPKD is not yet clear, there are promising therapies focused on by blocking the excessive activation of the mTOR pathway and cAMP pathway to slow disease progression. Animal experiments showed that mTOR inhibitors (sirolimus and everolimus) improved rodent models of polycystic kidney disease effect is very significant, but everolimus and sirolimus are potent immunosuppressant, may fatal side effects, and clinical trials have not achieved good results. So we need to explore more effective means of security.Numerous reports confirmed that AMP-activated protein kinase (AMP-activated protein kinase, AMPK) is one of the reasons down overactive mTOR pathway, regulated by AMPK levels can inhibit excessive activation of the mTOR pathway, and have achieved good results in animal models. By inhibiting dipeptidyl peptidase 4 (dipeptidyl peptidase 4, DPP4) activity can increase the level of AMPK is no doubt, but can inhibit excessive activation of the mTOR pathway improved ADPKD, whether over-expression of DPP4 presence in ADPKD patients and animal models thus excessive activation of the mTOR pathway, no answers to these two estions.The purpose of this project is to observe patients and experimental animals ADPKD kidney tissues DPP4 whether there is upregulated, and the use of DPP4 inhibitors, whether regulated AMPK with before, inhibiting mTOR activity, achieve the purpose of treatment of ADPKD.Methods1, DPP4 expression levels detected in patients and in animal models of ADPKD: collect ADPKD renal tissues of patients with kidney transplant donor tissue, DPP4 protein expression was determined by western blot both technie and compared; breeding polycystic kidney disease model Han:SPRD rats identified the wild-type (WT) and morbidity model (cy-/+), normal feeding to 12 weeks, in kidney tissue, using western blot assay DPP4 protein expression for comparison.2, animal experiments to inhibit DPP4 activity:Intervention drugs include AMPK activators metformin (Metformin), DPP4 inhibitor vildagliptin (Vildagliptin) and linagliptin (Linagliptin). Breeding polycystic kidney disease model Han:SPRD rats after birth to identify wild-type (WT) and morbidity model (cy-/+). The incidence model rats were divided into control group (Ctrl) and metformin (MET) group, vildagliptin (VIG) group, linagliptin (LIG) group.3 rats administered from 4 weeks after birth, in the first week 4/8/12 blood check kidney function, measured at 12 weeks 24 hours urine metabolic cages, and the animals were measured kidney weight kidney weight ratio extract protein, pathology row sweep the entire film surface.3, Experimental observation DPP4 cytostatic activity against cell proliferation:The human renal cyst lining epithelial cells were cultured WT9-12. In MTT observed at different concentrations of metformin, vildagliptin, linagliptin effect,24 hours,48 hours, 72 hours cell proliferation.4, inhibition mechanism of DPP4 active therapeutic ADPKD:Take different concentrations of metformin, WT9-12 cell vildagliptin, linagliptin treatment, protein content changes after Western blot analysis of technical intervention of AMPK. Take the aforementioned experimental extraction WT, Ctrl, MET, VIG, renal tissue in rat LIG group, western blot Determination AMPK, Akt, p70S6K protein content by.Results1, patients with ADPKD kidney tissues DPP4 expression was significantly higher than for kidney transplant (1.97 vs.0.60, P= 0.002), increased by about three times. Similarly in the case of kidneys, the incidence of rats with kidneys DPP4 expression increased by nearly three times (7.49 vs 1.14, P=0.001)-rats with polycystic kidney disease (/+cy).2, compared with the control group, metformin, vildagliptin and linagliptin could significantly reduce Han:Renal SPRD heavy weight ratio (KW/BW), cyst index, improve renal function. The index was not statistically different between the three groups administered group.3, metformin, vildagliptin, linagliptin can inhibit the proliferation WT9-12. Three drugs are present in a concentration-dependent manner,24 hours,48 hours,72 hours three time node 50nM concentrations of metformin WT9-12 growth inhibition rates of 34%, 60%,74%, respectively; 50nM Ludwig column Ting on WT9-12 cell growth inhibition rates were 14%,20%,28%; 5nM linagliptin on WT9-12 cell growth inhibition rates were 79%,86%,93%.4, after administration, metformin, expression pAMPK vildagliptin, linagliptin rat model of renal tissue were significantly higher than Ctrl group (P<0.001), were increased 2.7-fold,3.5-fold and 5 times; and vildagliptin group than in the metformin group (3.5 vs. 2.7, P<0.001), while the linagliptin group was significantly higher than the vildagliptin group (5.1 vs 2.7, P<0.001). And the control group compared to metformin (4.5 vs 5.1, P = 0.029), vildagliptin (3.9 vs 5.1, P<0.001), linagliptin (3.0 vs 5.1, P<0.001) can make Rats renal tissue overactive mTOR is inhibited significantly decreased the expression of p70S6K downstream products; vildagliptin group p70S6K protein expression is lower than the metformin group (3.9 vs 4.5, P= 0.045), linagliptin group than Ludwig column statin group (3.0 vs.3.9, P=0.001)..ConclusionsThis study found that ADPKD patients and rats with polycystic kidney tissues DPP4 overexpression. Use DPP4 inhibitors, may increase AMPK inhibit excessive activation of the mTOR pathway, inhibition of cell proliferation cyst, slow disease progression. ADPKD patients DPP4 overexpression caused excessive activation of mTOR may be one of the pathogenesis, inhibition of DPP4 activity, is one of the target for the treatment of ADPKD.