Youying Mao

Evaluation of sphingolipid metabolism in renal cortex of rats with streptozotocin-induced diabetes and the effects of rapamycin

BACKGROUND Abnormal lipid metabolism contributes to the pathogenesis of diabetes, but it is uncertain whether it plays a role in the development of diabetic nephropathy (DN). While rapamycin was shown to prevent DN development in streptozotocin (STZ)-induced diabetic rats in our previous studies, it is unknown if it intervenes with lipid metabolism. METHODS We divided the rats into four groups: normal control rats, rapamycin-treated normal rats, diabetic rats and rapamycin-treated DN rats. The apoptosis was evaluated by immunohistochemistry. The crude lipid and sphingolipid were extracted from rat renal cortex and analysed by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The expression of the three key enzymes in sphingolipid metabolism including serine palmitoyltransferase, acid sphingomyelinase and sphingomyelin synthase was measured by western blot and immunohistochemistry in rat renal cortex. RESULTS The level of apoptosis was increased in diabetic rats, and rapamycin treatment reduced apoptosis. STZ treatment significantly increased formation of many sphingolipids species through elevated de novo synthesis. These changes were inhibited by treatment with rapamycin. CONCLUSIONS Accumulation of sphingolipids contributes to STZ-induced diabetes, and the therapeutic effect of rapamycin on diabetic nephropathy is partly through suppression of sphingolipid abnormality.

A pilot study of GC/MS-based serum metabolic profiling of acute rejection in renal transplantation.

AIMS Acute allograft rejection is one of the important complications after renal transplantation, and it is a deleterious factor for long-term graft survival. Rejection is a complex pathophysiologic process, which has been explained by transcriptome and proteome in RNA transcripts and proteins level respectively. How are serum metabolite levels in response to acute rejection? Can metabolite levels in serum be used to diagnose and explain acute renal allograft rejection? METHODS Gas chromatograph-mass spectrometry (GC-MS) was used to analyze serum metabolome in 22 recipients of acute rejection and 15 stable renal transplant recipients. RESULTS 46 endogenous metabolites included amino acid, fatty acid, carbohydrate and other intermediate metabolites were identified in 37 recipients. Principal component analysis based on these metabolites discriminated acute rejection group from stable recipients. Among these metabolites, the levels of 17 metabolites were significant higher in rejection group than those in stable group. These included amino acid (phenylalanine, serine, glycine, threonine, valine), carbohydrate (galactose oxime, glycose, fructose), carboxylic acid, lipids and other metabolite such as lactate, urea and myo-inositol. The levels of 5 metabolites of alanine, lysine, leucine, aminomalonic acid and tetradecanoic acid were low in rejection group compared to stable group. The prediction accuracy of acute rejection was 77.3% and stable function was 100% by supervised clustering based on these 22 metabolites. CONCLUSIONS This study demonstrated that metabolic profile was changed in response to rejection process and renal function can be reflected by serum metabolite levels. This study showed potential capability to diagnose acute rejection by metabolome analysis.

Dual effects of statins therapy in systemic lupus erythematosus and SLE-related atherosclerosis: The potential role for regulatory T cells

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease associated with accelerated atherosclerosis independent of traditional risk factors. Statins, the 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors, have been widely prescribed for hyperlipidemia, which could slow the atherosclerosis progression, and reduce cardiovascular disease events. Nonetheless, accumulated evidences suggested that statins exert immunomodulatory and anti-inflammatory functions independent of their lipid-lowering effects. By the virtue of pleiotropic immunomodulatory property, statins may be applied for the treatment of both autoimmunity and atherosclerosis in patients with SLE. Interestingly, it has been well documented that regulatory T cells (Tregs) are involved in the pathogenesis of SLE as well as atherosclerosis. Meanwhile, studies have shown that statins could induce augmented number of Tregs with increased functional inhibitory properties. Thus, we hypothesized that the effect of statins ameliorating lupus disease manifestations and lupus-mediated atherogenesis might be mediated, at least partly, via the activation of Tregs. To our knowledge, this is the first hypothesis focused on that Tregs might be involved in the immunomodulatory effect of statins on SLE and SLE-related atherosclerosis.

Feasibility of diagnosing renal allograft dysfunction by oligonucleotide array: Gene expression profile correlates with histopathology

BACKGROUND Effective non-invasive monitoring method to tell histopathology is a big challenge in renal transplantation. METHODS We used 70-mer long oligonucleotide array with 449 immune related genes to determine gene expression profiles of peripheral blood mononuclear cells (PBMCs) under different immune status including stable renal function (TX), acute tubular necrosis (ATN), biopsy conformed acute rejection (AR), clinical rejection with pathology of borderline changes (BL), clinical rejection without biopsy proven/presumed rejection (PR) and renal dysfunction without rejection (NR). RESULTS Distinct molecular expression signatures in each group were found to correlate with histopathology. And we concluded that B cell chemokine CXCL13 and mast cell may play a role in renal allograft rejection through significant difference analysis and functional pathway analysis. CONCLUSIONS It provides a potential non-invasive method for monitoring renal allograft function and immune status of renal transplant recipients.

Diagnosis of C4d+ Renal Allograft Acute Humoral Rejection by Urine Protein Fingerprint Analysis

This study aimed to develop urine protein fingerprint models for the diagnosis of acute rejection (AR) and complement split product positive (C4d+) acute humoral rejection (AHR) following renal allograft transplantation. Urine samples from 101 renal transplant recipients were analysed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry combined with bioinformatics. The patients comprised 36 with stable allograft function (stable group), 10 with acute tubular necrosis (ATN) and 55 with AR (20 with C4d- acute cellular rejection [ACR] and 15 with C4d+ AHR). The ATN group was differentiated from the stable group with a sensitivity and specificity of 100% (pattern 1). The stable group was differentiated from the AR group with a specificity of 86.4% and a sensitivity of 85.4% (pattern 2). The C4d- ACR subgroup was differentiated from the C4d+ AHR subgroup with a specificity and sensitivity of 95% and 80%, respectively (pattern 3). It is concluded that urine protein fingerprint analysis can provide a noninvasive tool to diagnose AR and C4d+ AHR.

Effects of chimerism on the mice heart transplanted survival with the bone marrow infusion.

AIMS To evaluate the effects of chimerism on the mice heart transplanted survival with the bone marrow infusion. METHODS Bone marrow cells (BMCs) were obtained from BALB/c mice. These BMCs were injected into the irradiated (2Gy-Co60) C57BL/6 mice through femoral vein. Then Group A mice were treated with Cyclosporine (1mg/kg) for 21days and Group B were not treated with Cyclosporine. Group C were treated as the control group without BMCs infusion. Group D were treated with Cyclosporine (1mg/kg) for 21days pre-hearttransplantation without BMCs infusion. After 21days, the C57BL/6 mice received heart allografts from BALB/c. To determine the degree of chimerism in BMCs infusion recipients, peripheral blood were isolated on day 7, 14, 21. Allografts were harvested 10days after heart transplantation for the histological analysis. RESULTS (1) Chimerism detected in the peripheral blood of Group A mice on day 7 after BMCs infusion was 6.1±2.5%, on day 14 was 15.4±2.9% and on day 21 was 10.7±2.6%. For the Group B mice on day 7 after BMCs infusion, the chimerism was 2.8±1.1%, on day 14 was 11.2±4.8% and on day 21 was 7.4±3.7%. For the Groups C and D mice, no chimerism was observed. Group A mice had the tendency toward improved level of chimerism than Group B mice. (2) The survival time of Group A (n=6) was 13.0±1.4days which was significantly longer than Group B (n=6) with the survival time was 8.5±1.3days (p<0.001), also longer than the mice in Groups C and D, the survival time of which were 10.0±1.3days (p=0.008) and 9.4±1.1days (p=0.004). There is no significant difference among Groups B, C, and D. (3) The HE staining showed the much more seriously heart rejection in Groups B, C and D than Group A. CONCLUSIONS The chimerism was found in the BMCs infusion groups. Without the CsA treatment combined with chimerism could not protect the transplanted heart. There was no obvious evidence showed that the chimerism alone could improve the survival time of cardiac allografts in mice.

Effects of chlorpyrifos exposure on kidney Notch2-Jagged1 pathway of early prenatal embryo.

AIMS To evaluate the effects of this insecticide on the embryonic development of kidney and to assess the important role of Notch2-Jagged1 pathway in this duration. METHODS AND RESULTS Chlorpyrifos (CPF) 5 mg/kg/d were administrated on gestation 7.5-11.5 day by subcutaneous injection. On gestation 16.5 day, the normal embryo kidney developed through S shape duration to the original kidney, which had the nephrons and could start to secret the urine. But for the CPF-treated mice, the embryo kidney developed much more slowly, they did not show the S shape and the nephrons. The Notch2-Jagged1 pathway should be expressed stronger in the normal embryo kidney on gestation 16.5 day, but for the CPF-treated mice we found the obvious weak pathway staining. CONCLUSIONS CPF broke the Notch2-Jagged1 pathway during the embryo kidney development, and the Notch2-Jagged1 pathway plays an important role in the S shape to original kidney formation duration.