The role of regulatory T cells in the pathogenesis of acute kidney injury.

The incidence of acute kidney injury (AKI) is on the rise and is associated with high mortality; however, there are currently few effective treatments. Moreover, the relationship between Tregs and other components of the immune microenvironment (IME) in the pathogenesis of AKI remains unclear. We downloaded four publicly accessible AKI datasets, GSE61739, GSE67401, GSE19130, GSE81741, GSE19288 and GSE106993 from the gene expression omnibus (GEO) database. Additionally, we gathered two kidney single-cell sequencing (scRNA-seq) samples from the Department of Organ Transplantation at Zhujiang Hospital of Southern Medical University to investigate chronic kidney transplant rejection (CKTR). Moreover, we also collected three samples of normal kidney tissue from GSE131685. By analysing the differences in immune cells between the AKI and Non-AKI groups, we discovered that the Non-AKI group contained a significantly greater number of Tregs than the AKI group. Additionally, the activation of signalling pathways, such as inflammatory molecules secretion, immune response, glycolytic metabolism, NOTCH, FGF, NF-κB and TLR4, was significantly greater in the AKI group than in the Non-AKI group. Additionally, analysis of single-cell sequencing data revealed that Tregs in patients with chronic kidney rejection and in normal kidney tissue have distinct biology, including immune activation, cytokine production, and activation fractions of signalling pathways such as NOTCH and TLR4. In this study, we found significant differences in the IME between AKI and Non-AKI, including differences in Tregs cells and activation levels of biologically significant signalling pathways. Tregs were associated with lower activity of signalling pathways such as inflammatory response, inflammatory molecule secretion, immune activation, glycolysis.

Bone mesenchymal stem cells pretreated with erythropoietin enhance the effect to ameliorate cyclosporine A-induced nephrotoxicity in rats.

An increasing number of experiments and clinical trials have demonstrated the safety, feasibility, and efficacy of mesenchymal stem cells (MSCs)-based therapies for the treatment of various diseases. The main drawbacks of MSC therapy are the lack of specific homing after systemic infusion and early death of injected cells because of the injury micro-environment. We pretreated bone mesenchymal stem cells (BMSCs) with erythropoietin (EPO) to investigate their positive effect on cyclosporine A (CsA)-induced nephrotoxicity. BMSCs were incubated with different concentrations of EPO (10, 100, 500, and 1000 IU/mL) for 24 and 48 h, and their proliferation rate, cytoskeletal morphology, migration ability, and the expression of CXCR4 were evaluated to determine the optimal pretreatment conditions. To investigate the therapeutic effects of BMSCs pretreated with EPO in CsA-induced nephrotoxicity, we established CsA-induced in vitro and in vivo toxicity models. In our in vitro study, preconditioning of BMSCs with 500 IU/mL EPO for 48 h induced a marked increase in their proliferation rate, cytoskeletal rearrangement, migration in the scrape-healing assay, and migration toward injured HK2 cells. In vivo, EPO-BMSCs showed higher ability to improve renal function than BMSCs, and in CsA-induced rats treated with EPO-BMSCs, interstitial lymphocyte infiltration, tubular swelling, necrosis, and interstitial fibrosis decreased. We demonstrated that pretreatment with 500 IU/mL EPO before infusion markedly increased the homing ability of BMSCs, and obviously ameliorate CsA-induced nephrotoxicity in rats.

Ghrelin attenuates renal fibrosis and inflammation of obstructive nephropathy.

PURPOSE: Ghrelin is a gastric peptide that modulates multiple biological functions, of which the stimulation of food intake is the most well-known function. Ghrelin also exerts potential anti-inflammatory and antifibrotic properties in different organs but to our knowledge whether ghrelin inhibits the progression of renal fibrosis is unknown. Thus, we investigated the effect and underlying mechanisms of ghrelin in a rat model of renal fibrosis. MATERIALS AND METHODS: Male Sprague Dawley® rats were divided into 4 groups, including vehicle or ghrelin treated sham operated groups and vehicle or ghrelin treated unilateral ureteral obstruction groups. Kidneys harvested on postoperative day 7 or 14 were evaluated for renal inflammation, fibrosis and apoptosis, and the expression of profibrotic and proinflammatory factors. RESULTS: Ghrelin inhibited renal fibrosis by attenuating collagen production, extracellular matrix deposition, and α-smooth muscle actin and fibronectin expression. Ghrelin administration decreased macrophage infiltration and several proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1ß and monocyte chemotactic protein-1, as well as phosphorylated nuclear factor-κB p65. Ghrelin also inhibited myofibroblast accumulation by blocking the transforming growth factor-ß1/Smad3 signaling pathway. Furthermore, ghrelin attenuated renal tubular cell apoptosis and epithelial-mesenchymal transition processes induced by unilateral ureteral obstruction injury. CONCLUSIONS: These findings indicate that ghrelin is a potent antifibrotic agent that may have therapeutic potential in patients with obstructive nephropathy.

Posttransplant complications: molecular mechanisms and therapeutic interventions.

Posttransplantation complications pose a major challenge to the long-term survival and quality of life of organ transplant recipients. These complications encompass immune-mediated complications, infectious complications, metabolic complications, and malignancies, with each type influenced by various risk factors and pathological mechanisms. The molecular mechanisms underlying posttransplantation complications involve a complex interplay of immunological, metabolic, and oncogenic processes, including innate and adaptive immune activation, immunosuppressant side effects, and viral reactivation. Here, we provide a comprehensive overview of the clinical features, risk factors, and molecular mechanisms of major posttransplantation complications. We systematically summarize the current understanding of the immunological basis of allograft rejection and graft-versus-host disease, the metabolic dysregulation associated with immunosuppressive agents, and the role of oncogenic viruses in posttransplantation malignancies. Furthermore, we discuss potential prevention and intervention strategies based on these mechanistic insights, highlighting the importance of optimizing immunosuppressive regimens, enhancing infection prophylaxis, and implementing targeted therapies. We also emphasize the need for future research to develop individualized complication control strategies under the guidance of precision medicine, ultimately improving the prognosis and quality of life of transplant recipients.

CARARIME: Interactive web server for comprehensive analysis of renal allograft rejection in immune microenvironment.

Background: Renal transplantation is a very effective treatment for renal failure patients following kidney transplant. However, the clinical benefit is restricted by the high incidence of organ rejection. Therefore, there exists a wealth of literature regarding the mechanism of renal transplant rejection, including a large library of expression data. In recent years, research has shown the immune microenvironment to play an important role in renal transplant rejection. Nephrology web analysis tools currently exist to address chronic nephropathy, renal tumors and children's kidneys, but no such tool exists that analyses the impact of immune microenvironment in renal transplantation rejection. Methods: To fill this gap, we have developed a web page analysis tool called Comprehensive Analysis of Renal Allograft Rerejction in Immune Microenvironment (CARARIME). Results: CARARIME analyzes the gene expression and immune microenvironment of published renal transplant rejection cohorts, including differential analysis (gene expression and immune cells), prognosis analysis (logistics regression, Univariable Cox Regression and Kaplan Meier), correlation analysis, enrichment analysis (GSEA and ssGSEA), and ROC analysis. Conclusions: Using this tool, researchers can easily analyze the immune microenvironment in the context of renal transplant rejection by clicking on the available options, helping to further the development of approaches to renal transplant rejection in the immune microenvironment field. CARARIME can be found in http://www.cararime.com.

Single-Cell Profiling of Kidney Transplant Recipients With Immunosuppressive Treatment Reveals the Dynamic Immune Characteristics.

Kidney transplantation is currently the first choice of treatment for various types of end-stage renal failure, but there are major limitations in the application of immunosuppressive protocols after kidney transplantation. When the dose of immunosuppressant is too low, graft rejection occurs easily, while a dose that is too high can lead to graft loss. Therefore, it is very important to explore the immune status of patients receiving immunosuppressive agents after kidney transplantation. To compare the immune status of the recipient's whole peripheral blood before and after receipt of immunosuppressive agents, we used single-cell cytometry by time-of-flight (CyTOF) to detect the peripheral blood immune cells in five kidney transplant recipients (KTRs) from the Department of Organ Transplantation of Zhujiang Hospital of Southern Medical University before and after receiving immunosuppressive agents. Based on CyTOF analysis, we detected 363,342 live single immune cells. We found that the immune cell types of the KTRs before and after receipt of immunosuppressive agents were mainly divided into CD4+ T cells, CD8+ T cells, B cells, NK cells/γδ T cells, monocytes/macrophages, granulocytes, and dendritic cells (DCs). After further reclustering of the above cell types, it was found that the immune cell subclusters in the peripheral blood of patients underwent major changes after receipt of immunosuppressants. After receiving immunosuppressive therapy, the peripheral blood of KTRs had significantly increased levels of CD57+NK cells and significantly decreased levels of central memory CD4+ T cells, follicular helper CD4+ T cells, effector CD8+ T cells, effector memory CD8+ T cells and naive CD8+ T cells. This study used CyTOF to classify immune cells in the peripheral blood of KTRs before and after immunosuppressive treatment, further compared differences in the proportions of the main immune cell types and immune cell subgroups before and after receipt of immunosuppressants, and provided relatively accurate information for assessment and treatment strategies for KTRs.

Bone marrow derived mesenchymal stem cells pretreated with erythropoietin accelerate the repair of acute kidney injury.

BACKGROUND: Mesenchymal stem cells (MSCs) represent a promising treatment option for acute kidney injury (AKI). The main drawbacks of MSCs therapy, including the lack of specific homing after systemic infusion and early cell death in the inflammatory microenvironment, directly affect the therapeutic efficacy of MSCs. Erythropoietin (EPO)-preconditioning of MSCs promotes their therapeutic effect, however, the underlying mechanism remains unknown. In this study, we sought to investigate the efficacy and mechanism of EPO in bone marrow derived mesenchymal stem cells (BMSCs) for AKI treatment. RESULTS: We found that incubation of BMSCs with ischemia/reperfusion(I/R)-induced AKI kidney homogenate supernatant (KHS) caused apoptosis in BMSCs, which was decreased by EPO pretreatment, indicating that EPO protected the cells from apoptosis. Further, we showed that EPO up-regulated silent information regulator 1 (SIRT1) and Bcl-2 expression and down-regulated p53 expression. This effect was partially reversed by SIRT1 siRNA intervention. The anti-apoptotic effect of EPO in pretreated BMSCs may be mediated through the SIRT1 pathway. In a rat AKI model, 24 h after intravenous infusion, GFP-BMSCs were predominantly located in the lungs. However, EPO pretreatment reduced the lung entrapment of BMSCs and increased their distribution in the target organs. AKI rats infused with EPO-BMSCs had significantly lower levels of serum IL-1ß and TNF-α, and a significantly higher level of IL-10 as compared to rats infused with untreated BMSCs. The administration of EPO-BMSCs after reperfusion reduced serum creatinine, blood urea nitrogen, and pathological scores in I/R-AKI rats more effectively than BMSCs treatment did. CONCLUSIONS: Our data suggest that EPO pretreatment enhances the efficacy of BMSCs to improve the renal function and pathological presentation of I/R-AKI rats.

Characterization of aberrant pathways activation and immune microenviroment of BK virus associated nephropathy.

In the context of transplantation with the use of immunosuppressive drugs, BK virus infection has become the main cause of BK virus nephropathy(BKVN) in renal transplant recipients(KTRs). More importantly, BKVN may cause further allograft dysfunction and loss. However, the role of the immune microenvironment in the pathogenesis of BKVN remains unknown. Therefore, we collected microarray data of KTRs to elucidate the immune characteristics of BKVN. Via the CIBERSORT, we found that BKVN had relatively more activated memory CD4 T cells. Immunostaining showed that CD4+ and CD8+cells were significantly different between BKVN and stable allografts(STAs). In addition, the expression of immune-related genes(antigen presentation, cytotoxicity, and inflammation) was significantly higher in BKVN than in STAs. The results of gene set enrichment analysis(GSEA) and single-sample GSEA(ssGSEA) indicated that immune cell-,cytokine-,chemokine-, and inflammation-related pathways were significantly activated in BKVN, while metabolism- and renal development-related pathways were significantly downregulated in BKVN. In addition, the immune microenvironments of the peripheral blood in patients with BK viremia(BKV) or transplant kidney biopsy(TKB) with BKVN may be different. Overall, the immune microenvironment may play important roles in the occurrence and development of BKVN and provide a theoretical basis for preventing the occurrence of BKVN and finding novel treatments.

Single-cell analysis reveals immune landscape in kidneys of patients with chronic transplant rejection.

Rationale: Single-cell RNA sequencing (scRNA-seq) has provided an unbiased assessment of specific profiling of cell populations at the single-cell level. Conventional renal biopsy and bulk RNA-seq only average out the underlying differences, while the extent of chronic kidney transplant rejection (CKTR) and how it is shaped by cells and states in the kidney remain poorly characterized. Here, we analyzed cells from CKTR and matched healthy adult kidneys at single-cell resolution. Methods: High-quality transcriptomes were generated from three healthy human kidneys and two CKTR biopsies. Unsupervised clustering analysis of biopsy specimens was performed to identify fifteen distinct cell types, including major immune cells, renal cells and a few types of stromal cells. Single-sample gene set enrichment (ssGSEA) algorithm was utilized to explore functional differences between cell subpopulations and between CKTR and normal cells. Results: Natural killer T (NKT) cells formed five subclasses, representing CD4+ T cells, CD8+ T cells, cytotoxic T lymphocytes (CTLs), regulatory T cells (Tregs) and natural killer cells (NKs). Memory B cells were classified into two subtypes, representing reverse immune activation. Monocytes formed a classic CD14+ group and a nonclassical CD16+ group. We identified a novel subpopulation [myofibroblasts (MyoF)] in fibroblasts, which express collagen and extracellular matrix components. The CKTR group was characterized by increased numbers of immune cells and MyoF, leading to increased renal rejection and fibrosis. Conclusions: By assessing functional differences of subtype at single-cell resolution, we discovered different subtypes that correlated with distinct functions in CKTR. This resource provides deeper insights into CKTR biology that will be helpful in the diagnosis and treatment of CKTR.

Rutin ameliorates kidney interstitial fibrosis in rats with obstructive nephropathy.

Rutin reportedly conveys many beneficial effects, including renoprotection; however, it has not yet been demonstrated to have a renoprotective effect against obstructive nephropathy. The present study is the first to show a protective effect of rutin against obstructive renal injury induced by unilateral ureteral obstruction (UUO). A total of 24 male Wistar rats were randomly divided into four groups of six rats each, including vehicle- or rutin-treated sham operated groups, and vehicle- or rutin-treated UUO groups. Rats received daily oral gavage of rutin (100mg/kg) for 2weeks. All rats were euthanized on postoperative day 14. Histological findings showed that rutin administration significantly reduced renal interstitial injury and suppressed interstitial collagen deposits in UUO rats. Moreover, rutin decreased macrophage infiltration, proinflammatory cytokine expression and phosphorylation of nuclear factor-κB p65. Furthermore, rutin inhibited extracellular matrix accumulation by reducing expression of type I/III collagen and fibronectin. Rutin also prevented the epithelial-mesenchymal transition processes of renal tubular cells by decreasing α-smooth muscle actin expression and retaining E-cadherin expression. These effects of rutin were in parallel with the reductions in Smad3 activity and pivotal to the fibrogenic potential of TGF-ß1. Taken together, the renoprotective effects of rutin in obstructive nephropathy were likely due to anti-inflammatory effects and inhibition of TGF-ß1/Smad3 signaling.

[Early serological diagnosis of invasive aspergillosis in renal transplant recipients].

OBJECTIVE: To evaluate the clinical value of serum 1,3-beta-D-glucan (BG) and galactomannan (GM) detection for early diagnosis of invasive aspergillosis (IA) in patients after renal transplantation. METHODS: Blood samples collected from 69 renal transplant recipients were divided into diagnosis group, clinical diagnosis group, suspected diagnosis group, and non-infected group for detection of serum BG and GM. RESULTS: The mean serum levels of BG in the diagnosis group, clinical diagnosis group, and suspected diagnosis group were significantly higher than that in non-infected group (P<0.05). The sensitivity, specificity, and positive and negative predictive values of BG was 69.49%, 70%, 93.18% and 35.71% for IA diagnosis, respectively. The serum levels of GM in the 3 diagnosis groups were also significantly higher than that in the non-infected group (P<0.05) with the sensitivity, specificity, and positive and negative predictive values of 84.75%, 90%, 96.15% and 52.63% for IA diagnosis, respectively. CONCLUSION: Increased serum BG and GM levels can serve as the evidence for early diagnosis of IA with a high diagnostic sensitivity and specificity in renal transplant recipients.

Risk factors for graft survival in sensitized recipients of kidney transplantation.

OBJECTIVE: To investigate the independent prognostic factors for graft survival in sensitized recipients undergoing kidney transplantation, so as to identify the individuals at high risk of graft loss before transplantation. METHODS: A retrospective investigation was conducted in 102 sensitized kidney transplant recipients and 31 relative variables were analyzed with SPSS10.0 software. Using log-rank method, the influence of these variables on short- and long-term graft survivals was evaluated, and Kaplan-Meier analysis was performed to estimate the 1-, 3- and 5-year graft survival rates and half-life. Proportional hazards regression analysis (Cox model) was used to assess the relative risks of the potential variables. RESULTS: In the recipients with a mean half-life of 8.9 years, the 1-, 3- and 5-year graft survival rates were 90%, 85%, and 75%, respectively. By log-rank analysis, the factors affecting short- and long-term graft survivals were identified, namely the recipient age, times of transplantation, levels of panel reactive antibody and the post-operative anti-HLA-IgG antibody, HLA mismatch, renal function, time needing for graft function recovery, presence of acute rejection, delay of graft function recovery and infection, which affected the graft survival demonstrated by Cox model multivariate analysis. CONCLUSION: High-quality donor kidney and minimization of the risk factors for graft survival may insure successful kidney transplantation in sensitized recipients.

[Risk factors of acute rejection in sensitized kidney transplant recipients].

OBJECTIVE: To identify the risk factors of acute rejection in sensitized recipients undergoing kidney transplantation. METHODS: The clinical data of 102 sensitized kidney transplant recipients were retrospectively analyzed to evaluate the incidence of acute rejection in relation to panel reactive antibodies (PRA), amino acid residual match, postoperative elevation of PRA level and cytokine genotypes. RESULTS: During the follow-up, acute rejection occurred in totally 33 patients, and the incidence was higher in the recipients with high tumor necrosis factor (TNF)-alpha or high interleukin (IL)-10 producer genotype than in those with low TNF-alpha or low/intermediate IL-10 producer genotype (53.1%, 55.0% vs 22.8%, 20.9%, P(18)0.01 respectively). Acute rejection was even more frequent in the recipients with both high TNF-alpha and high/intermediate IL-10 producer genotypes than in those with low TNF-alpha and IL-10 producer genotype (66.7% vs 10.2%, P<0.01). No relations were found between TGF-beta1, IL-6, IFN-gamma gene polymorphisms and the incidence of acute rejection. The incidence in the recipients with PRA level of more than 40% was also higher than those with lower PRA level (<20%, 53.3% vs 22.7%, P<0.05), and the amino acid residual mismatch with 3-4 MM was responsible for a higher incidence in comparison with a mismatch with 0-1 MM (75.0% vs 24.1%, P<0.01). Postoperative elevation of PRA level also increased the risk of acute rejection (45.4% vs 22.4%, P<0.01). CONCLUSION: TNF-alpha, IL-10 gene polymorphism, PRA, amino acid residual mismatch, and increased postoperative PRA level may significantly influence acute rejection in sensitized kidney transplantation recipient, and preoperative evaluation of these factors may benefit the designing of immunosuppressive protocols for these patients.

[Apoptosis induction of rhesus peripheral blood lymphocytes].

OBJECTIVE: To establish a method for inducing apoptosis of rhesus peripheral blood lymphocytes (PBLs). METHODS: Rhesus PBLs were irradiated with X-ray, (60)Co gamma-rays and ultraviolet (UVC254 nm), respectively, and the cell apoptosis was evaluated with flow cytometry using annexin-V staining and propidium iodide staining. RESULTS: X-ray and (60)Co gamma-ray irradiation induced only low apoptotic rates of the PBLs, and UVC resulted in the highest apoptotic rate of about 60%. UVC irradiation of the PBLs in RPMI supplemented with 10% heat-inactivated fetal calf serum for 60 min at a distance of 20 cm led to an early apoptotic rate of 58.85% and necrotic rate of 11.5%. The apoptotic rate of PBLs increased in a dose- and time-dependent fashion. CONCLUSION: For inducing apoptosis of the rhesus PBLs, UVC can be more effective than X-ray and (60)Co gamma-ray. The highest apoptotic rate can be achieved when the rhesus PBLs in RPMI supplemented with 10% heat-inactivated fetal calf serum are exposed to UVC for 60 min at the distance of 20 cm.

[Half-dose Zenapax for acute rejection prevention after renal transplantation].

OBJECTIVE: To investigate the efficacy and safety of half-dose Zenapax for prevention of acute rejection after renal transplantation. METHODS: According to the immunosuppressive regimen and renal function after transplantation, patients were divided into 4 groups, namely groups A, B, C, and D of 90, 73, 11 and 13 patients, respectively. Blood creatinine measured 1 week after operation was <176.6 micromol/L in groups A and B, and was >353 micromol/L in groups C and D. Patients in groups A and C were given 25 mg Zenapax (0.5 mg/kg) and MMF 0.75 g before operation, and those in groups B and D had only MMF of 0.75 g. All patients were given Pred, CsA and MMF after operation, and the rejection episodes, the time of acute rejection onset, the rate of rejection reversal and complications were analyzed in the time period of 6 months after operation. RESULTS: After the operation, 13 patients (14.4%) developed acute rejection in group A, 18 (24.6%) in group B, 6 (54.5%) in group C and 7 (53.8%) in group D (P<0.01). The incidence of acute rejection in group B was significantly lower than that in groups C and D groups (P<0.01), and the latter two groups had similar incidence. The time of acute rejection onset ranged from 3 to 9 days postoperatively (mean 6.2-/+3.2 days) in group A, significantly delayed as compared with that in group B (range 2-8 days, mean 4.7-/+3.1 days), group C (range 2-7 days, mean 4.3-/+4.2 days) and group D group (range 2-9 days, mean 3.9-/+3.5 days), but the time was similar between groups B, C, and D (P>0.05). All acute rejection cases in group A was reversed, and the rate of reversal was 88.9% (16/18) in group B, 83.3% in group C, and 71.4% in group D. No significant differences were noted in such complications as infection, vascular injuries or gastrointestinal reactions between the 4 groups (P>0.05). CONCLUSION: Zenapax at the dose of 25 mg can safely decrease the risk of acute rejection in patients with good postoperative renal function recovery, but dose not seem effective in patients with delayed graft function recovery.