Proteomics for Biomarker Identification and Clinical Application in Kidney Disease

Constructing and Validating a Network of Potential Olfactory Sheathing Cell Transplants Regulating Spinal Cord Injury Progression

The pathology of spinal cord injury (SCI), including primary and secondary injuries, primarily involves hemorrhage, ischemia, edema, and inflammatory responses. Cell transplantation has been the most promising treatment for SCI in recent years; however, its specific molecular mechanism remains unclear. In this study, bioinformatics analysis verified by experiment was used to elucidate the hub genes associated with SCI and to discover the underlying molecular mechanisms of cell intervention. GSE46988 data were downloaded from the Gene Expression Omnibus dataset. In our study, differentially expressed genes (DEGs) were reanalyzed using the "R" software (R v4.2.1). Functional enrichment and protein-protein interaction network analyses were performed, and key modules and hub genes were identified. Network construction was performed for the hub genes and their associated miRNAs. Finally, a semi-quantitative analysis of hub genes and pathways was performed using quantitative real-time polymerase chain reaction. In total, 718 DEGs were identified, mainly enriched in immune and inflammation-related functions. We found that Cd4, Tp53, Rac2, and Akt3 differed between vehicle and transplanted groups, suggesting that these genes may play an essential role in the transplantation of olfactory ensheathing cells, while a toll-like receptor signaling pathway was significantly enriched in Gene set enrichment analysis, and then, the differences were statistically significant by experimentally verifying the expression of their associated molecules (Tlr4, Nf-κb, Ikkβ, Cxcl2, and Tnf-α). In addition, we searched for upstream regulatory molecules of these four central genes and constructed a regulatory network. This study is the first to construct a regulatory network for olfactory ensheathing cell transplantation in treating SCI, providing a new idea for SCI cell therapy.

Urinary peptidome analysis in CKD and IgA nephropathy

Background

Chronic kidney disease (CKD) has emerged as a significant challenge to human health and economic stability in aging societies worldwide. Current clinical practice strategies remain insufficient for the early identification of kidney dysfunction, and the differential diagnosis of immunoglobulin A nephropathy (IgAN) predominantly relies on invasive kidney biopsy procedures.

Methods

First, we assessed a case-control cohort to obtain urine samples from healthy controls and biopsy-confirmed CKD patients. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) was applied to detect urinary peptide and then these urinary peptide profiles were used to construct diagnostic models to distinguish CKD patients from controls and identify IgAN patients from other nephropathy patients. Furthermore, we assessed the robustness of the diagnostic models and their reproducibility by applying different algorithms.

Results

A rapid and accurate working platform for detecting CKD and its IgAN subtype based on urinary peptide pattern detected by MALDI-TOF MS was established. Naturally occurring urinary peptide profiles were used to construct a diagnostic model to distinguish CKD patients from controls and identify IgAN patients from other nephropathy patients. The performance of several algorithms was assessed and demonstrated that the robustness of the diagnostic models as well as their reproducibility were satisfactory.

Conclusions

The present findings suggest that the CKD-related and IgAN-specific urinary peptides discovered facilitate precise identification of CKD and its IgAN subtype, offering a dependable framework for screening conditions linked to renal dysfunction. This will aid in comprehending the pathogenesis of nephropathy and identifying potential protein targets for the clinical management of nephropathy.

Alterations in the Circulating Proteome Associated with Albuminuria

SIGNIFICANCE STATEMENT

We describe circulating proteins associated with albuminuria in a population of African American Study of Kidney Disease and Hypertension with CKD (AASK) using the largest proteomic platform to date: nearly 7000 circulating proteins, representing approximately 2000 new targets. Findings were replicated in a subset of a general population cohort with kidney disease (ARIC) and a population with CKD Chronic Renal Insufficiency Cohort (CRIC). In cross-sectional analysis, 104 proteins were significantly associated with albuminuria in the Black group, of which 67 of 77 available proteins were replicated in ARIC and 68 of 71 available proteins in CRIC. LMAN2, TNFSFR1B, and members of the ephrin superfamily had the strongest associations. Pathway analysis also demonstrated enrichment of ephrin family proteins.

BACKGROUND

Proteomic techniques have facilitated understanding of pathways that mediate decline in GFR. Albuminuria is a key component of CKD diagnosis, staging, and prognosis but has been less studied than GFR. We sought to investigate circulating proteins associated with higher albuminuria.

METHODS

We evaluated the cross-sectional associations of the blood proteome with albuminuria and longitudinally with doubling of albuminuria in the African American Study of Kidney Disease and Hypertension (AASK; 38% female; mean GFR 46; median urine protein-to-creatinine ratio 81 mg/g; n =703) and replicated in two external cohorts: a subset of the Atherosclerosis Risk in Communities (ARIC) study with CKD and the Chronic Renal Insufficiency Cohort (CRIC).

RESULTS

In cross-sectional analysis, 104 proteins were significantly associated with albuminuria in AASK, of which 67 of 77 available proteins were replicated in ARIC and 68 of 71 available proteins in CRIC. Proteins with the strongest associations included LMAN2, TNFSFR1B, and members of the ephrin superfamily. Pathway analysis also demonstrated enrichment of ephrin family proteins. Five proteins were significantly associated with worsening albuminuria in AASK, including LMAN2 and EFNA4, which were replicated in ARIC and CRIC.

CONCLUSIONS

Among individuals with CKD, large-scale proteomic analysis identified known and novel proteins associated with albuminuria and suggested a role for ephrin signaling in albuminuria progression.

Biomarker-Development Proteomics in Kidney Transplantation: An Updated Review

Kidney transplantation (KT) is the optimal therapeutic strategy for patients with end-stage renal disease. The key to post-transplantation management is careful surveillance of allograft function. Kidney injury may occur from several different causes that require different patient management approaches. However, routine clinical monitoring has several limitations and detects alterations only at a later stage of graft damage. Accurate new noninvasive biomarker molecules are clearly needed for continuous monitoring after KT in the hope that early diagnosis of allograft dysfunction will lead to an improvement in the clinical outcome. The advent of “omics sciences”, and in particular of proteomic technologies, has revolutionized medical research. Proteomic technologies allow us to achieve the identification, quantification, and functional characterization of proteins/peptides in biological samples such as urine or blood through supervised or targeted analysis. Many studies have investigated proteomic techniques as potential molecular markers discriminating among or predicting allograft outcomes. Proteomic studies in KT have explored the whole transplant process: donor, organ procurement, preservation, and posttransplant surgery. The current article reviews the most recent findings on proteomic studies in the setting of renal transplantation in order to better understand the effective potential of this new diagnostic approach.

Clinical applications of plasma proteomics and peptidomics: Towards precision medicine

In the context of precision medicine, disease treatment requires individualized strategies based on the underlying molecular characteristics to overcome therapeutic challenges posed by heterogeneity. For this purpose, it is essential to develop new biomarkers to diagnose, stratify, or possibly prevent diseases. Plasma is an available source of biomarkers that greatly reflects the physiological and pathological conditions of the body. An increasing number of studies are focusing on proteins and peptides, including many involving the Human Proteome Project (HPP) of the Human Proteome Organization (HUPO), and proteomics and peptidomics techniques are emerging as critical tools for developing novel precision medicine preventative measures. Excitingly, the emerging plasma proteomics and peptidomics toolbox exhibits a huge potential for studying pathogenesis of diseases (e.g., COVID-19 and cancer), identifying valuable biomarkers and improving clinical management. However, the enormous complexity and wide dynamic range of plasma proteins makes plasma proteome profiling challenging. Herein, we summarize the recent advances in plasma proteomics and peptidomics with a focus on their emerging roles in COVID-19 and cancer research, aiming to emphasize the significance of plasma proteomics and peptidomics in clinical applications and precision medicine.

Identifying hub genes and miRNAs in Crohn’s disease by bioinformatics analysis

Introduction: Crohn’s disease (CD) is a disease that manifests mainly as chronic inflammation of the gastrointestinal tract, which is still not well understood in terms of its pathogenesis. The aim of this study was to use bioinformatics analysis to identify differentially expressed genes (DEGs) and miRNAs with diagnostic and therapeutic potential in CD.

Materials and methods: Three CD datasets (GSE179285, GSE102133, GSE75214) were downloaded from the Gene Expression Omnibus (GEO) database. DEGs between normal and CD tissues were identified using the GEO2R online tool. The Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the DEGs were conducted using the clusterProfiler function in the R package. Protein-protein interaction network (PPI) analysis and visualization were performed with STRING and Cytoscape. Ten hub genes were identified using cytoHubba’s MCC algorithm and validated with datasets GSE6731 and GSE52746. Finally, the miRNA gene regulatory network was constructed by Cytoscape and NetworkAnalyst to predict potential microRNAs (miRNAs) associated with DEGs.

Results: A total of 97 DEGs were identified, consisting of 88 downregulated genes and 9 upregulated genes. The enriched functions and pathways of the DEGs include immune system process, response to stress, response to cytokine and extracellular region. KEGG pathway analysis indicates that the genes were significantly enriched in Cytokine-cytokine receptor interaction, IL-17 signaling pathway, Rheumatoid arthritis and TNF signaling pathway. In combination with the results of the protein-protein interaction (PPI) network and CytoHubba, 10 hub genes including IL1B, CXCL8, CXCL10, CXCL1, CXCL2, CXCL5, ICAM1, IL1RN, TIMP1 and MMP3 were selected. Based on the DEG-miRNAs network construction, 5 miRNAs including hsa-mir-21-5p, hsa-mir-93-5p, hsa-mir-98-5p, hsa-mir-1-3p and hsa-mir-335-5p were identified as potential critical miRNAs.

Conclusion: In conclusion, a total of 97 DEGs, 10 hub genes and 5 miRNAs that may be involved in the progression or occurrence of CD were identified in this study, which could be regarded as biomarkers of CD.

Application of peptide biomarkers in life analysis based on liquid chromatography-mass spectrometry technology

Biomedicine is developing rapidly in the 21st century. Among them, the qualitative and quantitative analysis of peptide biomarkers is of considerable importance for the diagnosis and therapy of diseases and the quality evaluation of drugs and food. The identification and quantitative analysis of peptides have been going on for decades. Traditionally, immunoassays or biological assays are generally used to quantify peptides in biological matrices. However, the selectivity and sensitivity of these methods cannot meet the requirements of the application. The separation and analysis technique of liquid chromatography-mass spectrometry (LC-MS) supplies a reliable alternative. In contrast to immunoassays, LC-MS methods are capable of providing the analytical prowess necessary to satisfy the demands of peptide biomarker research in the life sciences arena. This review article provides a historical account of the in-roads made by LC-MS technology for the detection of peptide biomarkers in the past 10 years, with the focus on the qualification/quantification developments and their applications.

Identification of Differentially Expressed Genes and miRNAs for Ulcerative Colitis Using Bioinformatics Analysis

Introduction: Ulcerative colitis (UC) is a chronic inflammatory disease of the intestine whose cause and underlying mechanisms are not fully understood. The aim of this study was to use bioinformatics analysis to identify differentially expressed genes (DEGs) with diagnostic and therapeutic potential in UC.

Materials and methods: Three UC datasets (GSE179285, GSE75214, GSE48958) were downloaded from the Gene Expression Omnibus (GEO) database. DEGs between normal and UC tissues were identified using the GEO2R online tool. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the DEGs were performed using Metascape. Protein-protein interaction network (PPI) analysis and visualization using STRING and Cytoscape. Finally, the miRNA gene regulatory network was constructed by Cytoscape to predict potential microRNAs (miRNAs) associated with DEGs.

Results: A total of 446 DEGs were identified, consisting of 309 upregulated genes and 137 downregulated genes. The enriched functions and pathways of the DEGs include extracellular matrix, regulation of cell adhesion, inflammatory response, response to cytokine, monocarboxylic acid metabolic process, response to toxic substance. The analysis of KEGG pathway indicates that the DEGs were significantly enriched in Complement and coagulation cascades, Amoebiasis, TNF signaling pathway, bile secretion, and Mineral absorption. Combining the results of the PPI network and CytoHubba, 9 hub genes including CXCL8, ICAM1, CXCR4, CD44, IL1B, MMP9, SPP1, TIMP1, and HIF1A were selected. Based on the DEG-miRNAs network construction, 7 miRNAs including miR-335-5p, mir-204-5p, miR-93-5p, miR106a-5p, miR-21-5p, miR-146a-5p, and miR-155-5p were identified as potential critical miRNAs.

Conclusion: In summary, we identified DEGs that may be involved in the progression or occurrence of UC. A total of 446 DEGs,9 hub genes and 7 miRNAs were identified, which may be considered as biomarkers of UC. Further studies, however, are needed to elucidate the biological functions of these genes in UC.

Discovery of NEU1 as a candidatedone. renal biomarker for proliferative lupus nephritis chronicity

OBJECTIVE

Proteomic approach was applied to identify candidate biomarkers of chronicity in patients with proliferative lupus nephritis (LN), and their clinicopathological significance and prognostic values were investigated.

METHODS

This study recruited 10 patients with proliferative LN and 6 normal controls (NCs) with proteomic data to compare protein expression profiles, 58 patients with proliferative LN and 10 NCs to verify proteomic data by immunohistochemistry, and 14 patients with proliferative LN with urine samples to evaluate the urinary expression of the biomarker by western blot assay. The composite endpoints included end-stage renal disease and ≥50% reduction from baseline estimated glomerular filtration rate (eGFR).

RESULTS

Proteomics detected 48 proteins upregulated in the group with chronicity index (CI) ≥1 compared with the CI=0 and NC groups. Further pathway analysis was enriched in 'other glycan degradation'. Neuraminidase 1 (NEU1), the most predominant protein in the pathway of other glycan degradation, was highly expressed in the kidney of patients with proliferative LN and could co-localise with podocyte, mesangial cells, endothelial cells and tubule cells. NEU1 expression in the tubulointerstitium area was significantly higher in the CI ≥1 group compared with the CI=0 and NC groups. Moreover, NEU1 expression was significantly correlated with serum creatinine value, eGFR and CI scores, respectively. Urinary NEU1 excretion in the CI ≥1 group was higher than in the CI=0 group and was also positively correlated with CI scores. Furthermore, the high expression of renal NEU1 was identified as an independent risk factor for renal prognosis by multivariate Cox regression analysis (HR, 6.462 (95% CI 1.025 to 40.732), p=0.047).

CONCLUSIONS

Renal NEU1 expression was associated with pathological CI scores and renal outcomes in patients with proliferative LN.

Identification of Immune-Related Genes in Sepsis due to Community-Acquired Pneumonia

Background

Immunosuppression has a key function in sepsis pathogenesis, so it is of great significance to find immune-related markers for the treatment of sepsis.

Methods

Datasets of community-acquired pneumonia (CAP) with sepsis from the ArrayExpress database were extracted. Differentially expressed genes (DEGs) between the CAP group and normal group by Limma package were performed. After calculation of immune score through the ESTIMATE algorithm, the DEGs were selected between the high immune score group and the low immune score group. Enrichment analysis of the intersected DEGs was conducted. Further, the protein-protein interaction (PPI) of the intersected DEGs was drawn by Metascape tools. Related publications of the key DEGs were searched in NCBI PubMed through Biopython models, and RT-qPCR was used to verify the expression of key genes.

Results

360 intersected DEGs (157 upregulated and 203 downregulated) were obtained between the two groups. Meanwhile, the intersected DEGs were enriched in 157 immune-related terms. The PPI of the DEGs was performed, and 8 models were obtained. In sepsis-related research, eight genes were obtained with degree ≥ 10, included in the models.

Conclusion

CXCR3, CCR7, HLA-DMA, and GPR18 might participate in the mechanism of CAP with sepsis.

Integrated metabolomics coupled with pattern recognition and pathway analysis to reveal molecular mechanism of cadmium-induced diabetic nephropathy

Diabetic nephropathy (DN) is becoming a worldwide public health problem and its pathophysiological mechanism is not well understood. Emerging evidences indicated that cadmium (Cd), an industrial material but also an environmental toxin, may be involved in the development and progression of diabetes and diabetes-related kidney disease. However, the underlying mechanism is still unclear. Herein, a DN animal model was constructed by exposing to Cd, the metabolomic profiling of DN mice were obtained by using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS), pattern recognition and pathway analysis were performed to screen potential biomarker. Moreover, western blotting was employed to verify the possible mechanism involved in the occurrence of Cd-induced DN. A total of 66 metabolites in serum have been screened out and identified as biomarkers, including free fatty acids, phospholipids, sphingomyelins, glycerides, and others. Significant differences were demonstrated between the metabolic profiles, including decreased levels of phospholipid and increased content of triglyceride, diacylglycerols, ceramide, lysophosphatidylcholine in Cd-induced DN mice compared with control. Protein expression level of p38 MAPK and Wnt/β-catenin were significantly increased. UPLC-Q-TOF/MS-based serum metabolomics coupled with pattern recognition methods and pathway analysis provide a powerful approach to identify potential biomarkers and is a new strategy to predict the underlying mechanism of disease caused by environmental toxicant.

Urinary Proteomics Identifying Novel Biomarkers for the Diagnosis and Phenotyping of Carotid Artery Stenosis

Background: Carotid artery stenosis (CAS) is caused by the formation of atherosclerotic plaques inside the arterial wall and accounts for 20–30% of all strokes. The development of an early, noninvasive diagnostic method and the identification of high-risk patients for ischemic stroke is essential to the management of CAS in clinical practice.

Methods: We used the data-independent acquisition (DIA) technique to conduct a urinary proteomic study in patients with CAS and healthy controls. We identified the potential diagnosis and risk stratification biomarkers of CAS. And Ingenuity pathway analysis was used for functional annotation of differentially expressed proteins (DEPs). Furthermore, receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic values of DEPs.

Results: A total of 194 DEPs were identified between CAS patients and healthy controls by DIA quantification. The bioinformatics analysis showed that these DEPs were correlated with the pathogenesis of CAS. We further identified 32 DEPs in symptomatic CAS compared to asymptomatic CAS, and biological function analysis revealed that these proteins are mainly related to immune/inflammatory pathways. Finally, a biomarker panel of six proteins (ACP2, PLD3, HLA-C, GGH, CALML3, and IL2RB) exhibited potential diagnostic value in CAS and good discriminative power for differentiating symptomatic and asymptomatic CAS with high sensitivity and specificity.

Conclusions: Our study identified novel potential urinary biomarkers for noninvasive early screening and risk stratification of CAS.

Diagnostic value of phosphatidylethanolamine binding protein 4 levels in patients receiving nursing interventions for advanced chronic kidney disease

OBJECTIVE

To explore the diagnostic role of phosphatidylethanolamine binding protein 4 (PEBP4) in patients with chronic kidney disease (CKD) receiving nursing interventions.

METHODS

ELISA was used to evaluate serum PEBP4 levels. Receiver-operating characteristic curve analysis was used to assess diagnostic accuracy. Spearman correlation analysis was used to assess the relationships between PEBP4 levels and biochemical indexes.

RESULTS

Serum PEBP4 was high in CKD patients compared with healthy individuals. PEBP4 levels were positively correlated with pathological stage in CKD patients. PEBP4 had higher sensitivity for diagnosis of CKD than common indexes including blood urea nitrogen, creatinine and C-reactive protein. Among CKD patients treated with calcium channel blockers, serum PEBP4 levels declined notably and were associated with concentrations of K+, Na+, Cl- and Ca2+. Nursing interventions significantly decreased serum PEBP4 levels. A significant association between serum PEBP4 level and ionic concentration was observed in CKD patients receiving nursing interventions.

CONCLUSIONS

This prospective study demonstrated that PEBP4 level might represent an effective diagnostic biomarker in CKD patients. PEBP4 also acted as a valuable care compliance factor for determining the necessity for nursing interventions. Nursing interventions restored ion channel function and subsequently resulted in decreased PEBP4 levels and proteinuria.

Altered Phosphorylation of Cytoskeleton Proteins in Peripheral Blood Mononuclear Cells Characterizes Chronic Antibody-Mediated Rejection in Kidney Transplantation

Chronic antibody-mediated rejection (CAMR) is the major cause of kidney transplant failure. The molecular mechanisms underlying this event are still poorly defined and this lack of knowledge deeply influences the potential therapeutic strategies. The aim of our study was to analyze the phosphoproteome of peripheral blood mononuclear cells (PBMCs), to identify cellular signaling networks differentially activated in CAMR. Phosphoproteins isolated from PBMCs of biopsy proven CAMR, kidney transplant recipients with normal graft function and histology and healthy immunocompetent individuals, have been investigated by proteomic analysis. Phosphoproteomic results were confirmed by Western blot and PBMCs’ confocal microscopy analyses. Overall, 38 PBMCs samples were analyzed. A differential analysis of PBMCs’ phosphoproteomes revealed an increase of lactotransferrin, actin-related protein 2 (ARPC2) and calgranulin-B in antibody-mediated rejection patients, compared to controls. Increased expression of phosphorylated ARPC2 and its correlation to F-actin filaments were confirmed in CAMR patients. Our results are the first evidence of altered cytoskeleton organization in circulating immune cells of CAMR patients. The increased expression of phosphorylated ARPC2 found in the PBMCs of our patients, and its association with derangement of F-actin filaments, might suggest that proteins regulating actin dynamics in immune cells could be involved in the mechanism of CAMR of kidney grafts.

The association between plasma proteomics and incident cardiovascular disease identifies MMP-12 as a promising cardiovascular risk marker in patients with chronic kidney disease

BACKGROUND AND AIMS

Previous proteomics efforts in patients with chronic kidney disease (CKD) have predominantly evaluated urinary protein levels. Therefore, our aim was to investigate the association between plasma levels of 80 cardiovascular disease-related proteins and the risk of major adverse cardiovascular events (MACE) in patients with CKD.

METHODS

Individuals with CKD stages 3-5 (eGFR below 60 ml min-1 [1.73 m]-2) from three community-based cohorts (PIVUS, ULSAM, SAVA), one diabetes cohort (CARDIPP) and one cohort with peripheral artery disease patients (PADVA) with information on 80 plasma protein biomarkers, assessed with a proximity extension assay, and follow-up data on incident MACE, were used as discovery sample. To validate findings and to asses generalizability to patients with CKD in clinical practice, an outpatient CKD-cohort (Malnutrition, Inflammation and Vascular Calcification (MIVC)) was used as replication sample.

RESULTS

In the discovery sample (total n = 1316), 249 individuals experienced MACE during 7.0 ± 2.9 years (range 0.005-12.9) of follow-up, and in the replication sample, 71 MACE events in 283 individuals over a mean ± SD change of 2.9 ± 1.2 years (range 0.1-4.0) were documented. Applying Bonferroni correction, 18 proteins were significantly associated with risk of MACE in the discovery cohort, adjusting for age and sex in order of significance, GDF-15, FGF-23, REN, FABP4, IL6, TNF-R1, AGRP, MMP-12, AM, KIM-1, TRAILR2, TNFR2, CTSL1, CSF1, PlGF, CA-125, CCL20 and PAR-1 (p < 0.000625 for all). Only matrix metalloproteinase 12 (MMP-12) was significantly associated with an increased risk of MACE in the replication sample (hazard ratio (HR) per SD increase, 1.36, 95% CI (1.07-1.75), p = 0.013).

CONCLUSIONS

Our proteomics analyses identified plasma MMP-12 as a promising cardiovascular risk marker in patients with CKD.

Bioinformatics-Based Study to Investigate Potential Differentially Expressed Genes and miRNAs in Pediatric Sepsis

BACKGROUND Sepsis is an extremely common health issue with a considerable mortality rate in children. Our understanding about the pathogenic mechanisms of sepsis is limited. The aim of this study was to identify the differential expression genes (DEGs) in pediatric sepsis through comprehensive analysis, and to provide specific insights for the clinical sepsis therapies in children. MATERIAL AND METHODS Three pediatric gene expression profiles (GSE25504, GSE26378, GSE26440) were downloaded from the Gene Expression Omnibus (GEO) database. The difference expression genes (DEGs) between pediatric sepsis and normal control group were screened with the GEO2R online tool. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the DEGs were performed. Cytoscape with CytoHubba were used to identify the hub genes. Finally, NetworkAnalyst was used to construct the targeted microRNAs (miRNAs) of the hub genes. RESULTS Totally, 160 overlapping upward genes and 61 downward genes were identified. In addition, 5 KEGG pathways, including hematopoietic cell lineage, Staphylococcus aureus infection, starch and sucrose metabolism, osteoclast differentiation, and tumor necrosis factor (TNF) signaling pathway, were significantly enriched using a database for labeling, visualization, and synthetic discovery. In combination with the results of the protein-protein interaction (PPI) network and CytoHubba, 9 hub genes including ITGAM, TLR8, IL1ß, MMP9, MPO, FPR2, ELANE, SPI1, and C3AR1 were selected. Combined with DEG-miRNAs visualization, 5 miRNAs, including has-miR-204-5p, has-miR-211-5p, has-miR-590-5p, and has-miR-21-5p, were predicted as possibly the key miRNAs. CONCLUSIONS Our findings will contribute to identification of potential biomarkers and novel strategies for pediatric sepsis treatment.

Proteomic analysis of rat kidney under maleic acid treatment by SWATH-MS technology

RATIONALE

Maleic acid is an industrial-grade chemical that is often used in adhesives, stabilizers, and preservatives. It is unknown whether long-term consumption of maleic acid modified starch is harmful to humans. However, many studies have indicated that maleic acid causes renal tubular damage in animal models, even as the associated pathways remain unclear. Sequential window acquisition of all theoretical fragment ion spectra (SWATH) is the most innovative of the label-free quantitative technologies which have better quantification performance. Therefore, SWATH technology was used to investigate the effect of maleic acid on the rat kidney proteome in this study.

METHODS

Sprague-Dawley(SD) rats were treated with 0 mg/kg (control), 6 mg/kg (low-dose), 10 mg/kg (medium-dose), and 60 mg/kg (high-dose) of maleic acid. After kidney protein extraction, 28% SDS-PAGE was used, followed by in-gel digestion and desalting. Next, the samples were analyzed with ultra-performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (Q-TOF MS), and data-dependent acquisition (DDA) and SWATH technology were also used. The gene ontology and pathway analysis were accomplished. Ultimately, these protein biomarkers were validated by using scheduled high-resolution multiple reaction monitoring (sMRM^HR ).

RESULTS

Comparisons of the control group with the other three groups revealed that 95, 130, and 103 proteins were expressed at significantly different levels in the control group and in the low-dose, medium-dose, and high-dose groups, respectively. According to the gene ontology analysis, the major processes that these proteins were involved in were metabolic processes, biological regulation, cellular processes, and responses to stimuli; the major functions that these proteins were involved in were binding, hydrolase activity, catalytic activity, and oxidoreductase activity; and the major cellular components hat they were involved in were the cytoplasm, extracellular region, membrane, and mitochondria. According to the KEGG pathway analysis, these proteins were involved in 35 pathways, five of which, the carbohydrate metabolism, folate biosynthesis, renal tubular resorption, amino acid metabolism, and Ras signaling pathways, are discussed in this study. Ultimately, 19 proteins involved in 12 important pathways were validated by sMRM^HR .

CONCLUSIONS

It was demonstrated that maleic acid caused insufficient energy production, which might lead to a decrease in the activity of the sodium-potassium ATP pump and hydrogen ion ATP pump, which could in turn have caused renal tubular resorption and hydrogen ion regulation to be blocked, thus leading to the accumulation of hydrogen ions in the renal tubules, which would then result in renal tubular acidification followed finally by Fanconi syndrome.

Urinary Peptidomic Biomarkers in Kidney Diseases

In order to effectively develop personalized medicine for kidney diseases we urgently need to develop highly accurate biomarkers for use in the clinic, since current biomarkers of kidney damage (changes in serum creatinine and/or urine albumin excretion) apply to a later stage of disease, lack accuracy, and are not connected with molecular pathophysiology. Analysis of urine peptide content (urinary peptidomics) has emerged as one of the most attractive areas in disease biomarker discovery. Urinary peptidome analysis allows the detection of short and long-term physiological or pathological changes occurring within the kidney. Urinary peptidomics has been applied extensively for several years now in renal patients, and may greatly improve kidney disease management by supporting earlier and more accurate detection, prognostic assessment, and prediction of response to treatment. It also promises better understanding of kidney disease pathophysiology, and has been proposed as a “liquid biopsy” to discriminate various types of renal disorders. Furthermore, proteins being the major drug targets, peptidome analysis may allow one to evaluate the effects of therapies at the protein signaling pathway level. We here review the most recent findings on urinary peptidomics in the setting of the most common kidney diseases.

Chronic kidney disease: Biomarker diagnosis to therapeutic targets

Chronic kidney disease (CKD), characterized as renal dysfunction, is recognized as a major public health problem with high morbidity and mortality worldwide. Unfortunately, there are no obvious clinical symptoms in early stage disease until severe damage has occurred. Further complicating early diagnosis and treatment is the lack of sensitive and specific biomarkers. As such, novel biomarkers are urgently needed. Metabolomics has shown an increasing potential for identifying underlying disease mechanisms, facilitating clinical diagnosis and developing pharmaceutical treatments for CKD. Recent advances in metabolomics revealed that CKD was closely associated with the dysregulation of numerous metabolites, such as amino acids, lipids, nucleotides and glycoses, that might be exploited as potential biomarkers. In this review, we summarize recent metabolomic applications based on animal model studies and in patients with CKD and highlight several biomarkers that may play important roles in diagnosis, intervention and development of new therapeutic strategies.

Early detection of unilateral ureteral obstruction by desorption electrospray ionization mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) is an emerging analytical tool for rapid in situ assessment of metabolomic profiles on tissue sections without tissue pretreatment or labeling. We applied DESI-MS to identify candidate metabolic biomarkers associated with kidney injury at the early stage. DESI-MS was performed on sections of kidneys from 80 mice over a time course following unilateral ureteral obstruction (UUO) and compared to sham controls. A predictive model of renal damage was constructed using the LASSO (least absolute shrinkage and selection operator) method. Levels of lipid and small metabolites were significantly altered and glycerophospholipids comprised a significant fraction of altered species. These changes correlate with altered expression of lipid metabolic genes, with most genes showing decreased expression. However, rapid upregulation of PG(22:6/22:6) level appeared to be a hitherto unknown feature of the metabolic shift observed in UUO. Using LASSO and SAM (significance analysis of microarrays), we identified a set of well-measured metabolites that accurately predicted UUO-induced renal damage that was detectable by 12 h after UUO, prior to apparent histological changes. Thus, DESI-MS could serve as a useful adjunct to histology in identifying renal damage and demonstrates early and broad changes in membrane associated lipids.

TMT-Based Proteomics Profiling of Bovine Liver Underscores Protein Markers of Anabolic Treatments

Illegal use of growth promoter compounds in food production exposes consumers to health risk. Surveillance of such practices is based on direct detection of drugs or related metabolites by HPLC-MS/MS. Screening strategies focusing on indirect biological responses are considered promising tools to improve surveillance. In this study, an untargeted shotgun proteomics approach based on tandem mass tags (TMTs) is carried out to identify proteins altered in bovine liver after different anabolic treatments. Three controlled pharmacological treatments with dexamethasone, a combination of dexamethasone and clenbuterol, or a combination of sexual steroids (trenbolone and estradiol) are analyzed. Untargeted TMT analysis of liver digests by high resolution MS allowed for the relative quantification of proteins. Thanks to partial least squarediscriminant analysis, a set of proteins capable to classify animals treated with dexamethasone alone (11 proteins), or in combination with clenbuterol (13 proteins) are identified. No significant difference is found upon administration of sexual steroids. After relative quantification of candidate markers by parallel reaction monitoring (PRM), two predictive models are trained to validate protein markers. Finally, an independent animal set of control bulls and bulls treated with dexamethasone is analyzed by PRM to further validate a predictive model giving an accuracy of 100%.

Comprehensive lipidomic, metabolomic and proteomic profiling reveals the role of immune system in vitiligo

BACKGROUND

Vitiligo is a common depigmentation disorder resulting from destruction of melanocytes, and has both genetic and environmental influences. Although genomic analyses have been performed to investigate the pathogenesis of vitiligo, the lipidomics, metabolomics and proteomics of serum have not been reported, and the role of small molecules and serum proteins in vitiligo remains unknown.

AIM

To study the metabolite and protein profiles in patients with vitiligo and healthy controls (HCs).

METHODS

Plasma samples from 60 participants (29 patients with vitiligo and 31 HCs) were analysed. Untargeted lipidomics, metabolomics and isobaric tags for relative and absolute quantification-based proteomics were performed using high performance liquid chromatography-tandem mass spectrometry. In addition, to validate differentially expressed metabolites in patients with vitiligo, plasma enzyme-linked immunosorbent assay was performed.

RESULTS

We identified differential expression of several metabolites and proteins involved in the immune system. Among these metabolites and proteins, lysophosphatidylcholine, platelet-activating factor, sn-glycerol-3-phosphocholine, succinic acid, CXCL4 and CXCL7 were significantly elevated in the plasma of patients with vitiligo, while aspartate was downregulated.

CONCLUSION

Our study has characterized several serum metabolites and proteins that could be potential candidate biomarkers in vitiligo, and provides a comprehensive insight into the role of immune system and aspartate metabolism in vitiligo.

Unilateral ureteral obstruction causes gut microbial dysbiosis and metabolome disorders contributing to tubulointerstitial fibrosis

Chronic kidney disease (CKD) increases the risk and prevalence of cardiovascular disease (CVD) morbidity and mortality. Recent studies have revealed marked changes in the composition of the microbiome and the metabolome and their potential influence in renal disease and CVD via the accumulation of microbial-derived uremic toxins. However, the effect of unilateral ureteral obstruction (UUO) on the gut microbiome and circulating metabolites is unknown. Male Sprague-Dawley rats were randomized to UUO and sham-operated control groups. Renal histology, colonic microbiota, and plasma metabolites were examined two weeks later. We employed 16S rRNA sequence and untargeted metabolomic analyses to explore the changes in colonic microbiota and plasma metabolites and their relationship with tubulointerstitial fibrosis (TIF). The UUO rats exhibited tubular atrophy and dilatation, interstitial fibrosis and inflammatory cell infiltration in the obstructed kidney. UUO rats showed significant colonic enrichment and depletion of genera. Significant differences were identified in 219 plasma metabolites involved in lipid, amino acid, and bile acid metabolism, which were consistent with gut microbiota-related metabolism. Interestingly, tryptophan and its metabolites kynurenine, 5-hydroxytryptophan and 5-hydroxytryptamine levels, which were linked with TIF, correlated with nine specific genera. Plasma tryptophan level was positively correlated with Clostridium IV, Turicibacter, Pseudomonas and Lactobacillales, and negatively correlated with Oscillibacter, Blautia, and Intestinimonas, which possess the genes encoding tryptophan synthase (K16187), indoleamine 2,3-dioxygenase (K00463) and tryptophan 2,3-dioxygenase (K00453) and their corresponding enzymes (EC:1.13.11.52 and EC:1.13.11.11) that exacerbate TIF. In conclusion, UUO results in profound changes in the gut microbiome and circulating metabolites, events that contribute to the pathogenesis of inflammation and TIF.

AKF-PD alleviates diabetic nephropathy via blocking the RAGE/AGEs/NOX and PKC/NOX Pathways

Diabetic nephropathy (DN) is a major complication of diabetes. Currently, drugs are not available to effectively control the disease. Fluorofenidone (AKF-PD) is a recently developed drug; it possesses activities in reducing DN progression in preclinical research. Nonetheless, its renal protection and the underlying mechanisms have not been thoroughly investigated. We report here that AKF-PD significantly alleviatesrenal oxidative stress (OS) in db/dbmice through downregulation of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase and upregulation of glutathione peroxidase and superoxide dismutase, thereby protecting kidney from DN pathogenesis. AKF-PD likely reduces OS through the advanced glycation end products (AGE) and protein kinase C (PKC) pathways. While renal AGEs, PKCα, PKCβ, and NADPH oxidase 4 (NOX4) were all substantially upregulated in db/db mice compared to db/m animals, AKF-PD robustly downregulated all these events to the basal levelsdetected in db/m mice. In primary human renal mesangial cells (HMCs), high glucose (HG) elevated receptor for advanced glycation endproducts (RAGE), PKCα, PKCβ and NOX4 activity, and induced the production of reactive oxygen species (ROS); these events were all inhibited by AKF-PD. Furthermore, HG led to mitochondrial damagein HMCs;AKF-PD conferred protection on the damage. Knockdown of either PKCα or PKCβ reduced HG-induced ROS production and mitochondrial damage in HMCs. The knockdown significantly enhanced AKF-PD-mediated inhibition of ROS production and mitochondrial damage in HG-treated HMCs. Collectively, our study demonstrates that AKF-PD protects renal function under diabetes conditions in part through inhibition of OS during DN pathogenesis. AKF-PD can be explored for clinical applications in DN therapy.

Deletion of Dicer blocks osteogenic differentiation via the inhibition of Wnt signalling

Micro (mi)RNAs are small, non‑coding RNAs and have been reported to have important roles in the epigenetic control of bone development. miRNAs markedly regulate osteoblast differentiation through stages of maturation as well as the activities of osteogenic signaling pathways. Dicer is an important endoribonuclease that regulates miRNA maturation. Previous studies have demonstrated that Dicer deletion decreases fetal survival and bone formation, while excision in differentiated osteoblasts increases bone mass. However, the underlying molecular mechanisms remain unclear. In the present study, whether the deletion of Dicer affects Wnt signaling, which exhibits important roles during osteogenesis, was investigated. Bone marrow stromal cells (BMSCs) were used as an osteogenic model. Dynamic changes of seven Wnt genes and downstream T‑cell factor 1 (Tcf‑1)/lymphoid enhancing binding factor were observed during the osteogenic differentiation of BMSCs, which revealed different roles at early and late differentiation stages. Following the stable knockdown of Dicer in BMSCs using lentiviral short hairpin RNA, osteogenic differentiation was blocked, and the levels of important osteogenic differentiation markers (runt related transcription factor 2 and alkaline phosphatase) were markedly inhibited. Furthermore, stage specific regulation of Wnt genes in Dicer‑deficient BMSCs was investigated in the present study. At the early differentiation stage (days 5‑7), knockdown of Dicer led to the inhibition of Wnt1, Wnt7 and Wnt10b, as well as the upregulation of Wnt4, Wnt10a and Tcf‑1. At the late stage of differentiation (days 14‑21), knockdown of Dicer significantly suppressed the expression levels of all of the included Wnt genes as well as Tcf‑1, with the exception of Wnt10a. The upregulation of Wnt10a following the deletion of Dicer was maintained throughout all stages of differentiation. In addition, differential regulation of Wnt genes and Tcf‑1 were revealed to be associated with dynamic changes in their expression levels during osteogenic differentiation. Furthermore, the four putative Wnt10a‑targeting miRNAs were investigated in the present study, and the results demonstrated that they were upregulated during osteogenic differentiation, which suggested that inhibition of Wnt10a may be an important factor associated with osteogenic differentiation. In conclusion, the present study investigated the mechanism underlying the regulation of Wnt signalling by Dicer during osteogenesis, and identified potential miRNAs targeting the components of Wnt signalling influenced by Dicer. Collectively, the present study identified the association between Dicer and Wnt signalling during bone development.

NMR and MS urinary metabolic phenotyping in kidney diseases is fit-for-purpose in the presence of a protease inhibitor

When using an appropriate data analysis pipeline, protease inhibitor (PI)-containing urine samples are fit-for-purpose for metabolic phenotyping of patients with nephrotic syndrome and proteinuria.

Natural products for the prevention and treatment of kidney disease

BACKGROUND

Chronic kidney disease (CKD) is one of the common causes resulting in a high morbidity and mortality. Renal fibrosis is the main pathological features of CKD. Natural products have begun to gain widely popularity worldwide for promoting healthcare and preventing CKD, and have been used as a conventional or complementary therapy for CKD treatment.

PURPOSE

The present paper reviewed the therapeutic effects of natural products on CKD and revealed the molecular mechanisms of their anti-fibrosis.

METHODS

All the available information on natural products against renal fibrosis was collected via a library and electronic search (using Web of Science, Pubmed, ScienceDirect, Splinker, etc.).

RESULTS

Accumulated evidence demonstrated that natural products exhibited the beneficial effects for CKD treatment and against renal fibrosis. This review presents an overview of the molecular mechanism of CKD and natural products against renal fibrosis, followed by an in-depth discussion of their molecular mechanism of natural products including isolated compounds and crude extracts against renal fibrosis in vitro and in vivo. A number of isolated compounds have been confirmed to retard renal fibrosis.

CONCLUSION

The review provides comprehensive insights into pathophysiological mechanisms of CKD and natural products against renal fibrosis. Particular challenges are presented and placed within the context of future applications of natural products against renal fibrosis.

Yinchenhao Decoction Alleviates Liver Fibrosis by Regulating Bile Acid Metabolism and TGF-β/Smad/ERK Signalling Pathway

Yinchenhao decoction (YCHD), comprising Yinchenhao (Artemisiae Scopariae Herba), Zhizi (Gardeniae Fructus) and Dahuang (Radix Rhei et Rhizoma), is widely used for treating various diseases. We aimed to investigate the bile acid metabolic mechanism of YCHD in dimethylnitrosamine (DMN)-induced liver fibrosis model. Rats received DMN (10 mg/kg, intraperitoneally) for four successive weeks for liver fibrosis induction and were treated with YCHD for the last 2 weeks. Histopathological analysis showed that YCHD prevented DMN-induced histopathological changes in liver tissues. Serum liver function in YCHD group improved. Ultraperformance liquid chromatography-mass spectrometry analysis showed that YCHD significantly restored both free and conjugated bile acid levels increased by DMN, to normal levels. RT-qPCR results showed that YCHD treatment upregulated the expression of genes related to bile acid synthesis, reabsorption, and excretion. Western blotting analysis showed that YCHD downregulated α-SMA, TGF-β1, p-Smad3, and p-ERK1/2 expression in chenodeoxycholic acid (CDCA)-activated hepatic stellate cells (HSCs). The viability of CDCA-activated HSCs significantly increased after treatment with YCHD and PD98059 (an ERK inhibitor) compared to YCHD treatment alone. Our findings suggest that YCHD alleviated DMN-induced liver fibrosis by regulating enzymes responsible for bile acid metabolism. Additionally, it inhibits CDCA-induced HSC proliferation and activation via TGF-β1/Smad/ERK signalling pathway.

Validation of a Novel Modified Aptamer-Based Array Proteomic Platform in Patients with End-Stage Renal Disease

End stage renal disease (ESRD) is characterized by complex metabolic abnormalities, yet the clinical relevance of specific biomarkers remains unclear. The development of multiplex diagnostic platforms is creating opportunities to develop novel diagnostic and therapeutic approaches. SOMAscan is an innovative multiplex proteomic platform which can measure >1300 proteins. In the present study, we performed SOMAscan analysis of plasma samples and validated the measurements by comparison with selected biomarkers. We compared concentrations of SOMAscan-measured prostate specific antigen (PSA) between males and females, and validated SOMAscan concentrations of fibroblast growth factor 23 (FGF23), FGF receptor 1 (FGFR1), and FGFR4 using Enzyme-Linked immunosorbent assay (ELISA). The median (25th and 75th percentile) SOMAscan PSA level in males and females was 4304.7 (1815.4 to 7259.5) and 547.8 (521.8 to 993.4) relative fluorescence units (p = 0.002), respectively, suggesting biological plausibility. Pearson correlation between SOMAscan and ELISA was high for FGF23 (R = 0.95, p < 0.001) and FGFR4 (R = 0.69, p < 0.001), indicating significant positive correlation, while a weak correlation was found for FGFR1 (R = 0.13, p = 0.16). In conclusion, there is a good to near-perfect correlation between SOMAscan and standard immunoassays for FGF23 and FGFR4, but not for FGFR1. This technology may be useful to simultaneously measure a large number of plasma proteins in ESRD, and identify clinically important prognostic markers to predict outcomes.

A blockade of PI3Kγ signaling effectively mitigates angiotensin II-induced renal injury and fibrosis in a mouse model

Chronic kidney disease (CKD) poses a formidable challenge for public healthcare worldwide as vast majority of patients with CKD are also at risk of accelerated cardiovascular disease and death. Renal fibrosis is the common manifestation of CKD that usually leads to end-stage renal disease although the molecular events leading to chronic renal fibrosis and eventually chronic renal failure remain to be fully understood. Nonetheless, emerging evidence suggests that an aberrant activation of PI3Kγ signaling may play an important role in regulating profibrotic phenotypes. Here, we investigate whether a blockade of PI3Kγ signaling exerts any beneficial effect on alleviating kidney injury and renal fibrosis. Using a mouse model of angiotensin II (Ang II)-induced renal damage, we demonstrate that PI3Kγ inhibitor AS605240 effectively mitigates Ang II-induced increases in serum creatinine and blood urea nitrogen, renal interstitial collagen deposition, the accumulation of ECM proteins and the expression of α-Sma and fibrosis-related genes in vivo. Mechanistically, we reveal that AS605240 effectively inhibits Ang II-induced cell proliferation and phosphorylation of Akt in fibroblast cells. Furthermore, we demonstrate that Ang II-upregulated expression of IL-6, Tnf-α, IL-1β and Tgf-β1 is significantly attenuated in the mice treated with AS605240. Taken together, our results demonstrate that PI3Kγ may function as a critical mediator of Ang II-induced renal injury and fibrosis. It is thus conceivable that targeted inhibition of PI3Kγ signaling may constitute a novel therapeutic approach to the clinical management of renal fibrosis, renal hypertension and/or CKD.

New insights into TGF-β/Smad signaling in tissue fibrosis

Transforming growth factor-β1 (TGF-β1) is considered as a crucial mediator in tissue fibrosis and causes tissue scarring largely by activating its downstream small mother against decapentaplegic (Smad) signaling. Different TGF-β signalings play different roles in fibrogenesis. TGF-β1 directly activates Smad signaling which triggers pro-fibrotic gene overexpression. Excessive studies have demonstrated that dysregulation of TGF-β1/Smad pathway was an important pathogenic mechanism in tissue fibrosis. Smad2 and Smad3 are the two major downstream regulator that promote TGF-β1-mediated tissue fibrosis, while Smad7 serves as a negative feedback regulator of TGF-β1/Smad pathway thereby protects against TGF-β1-mediated fibrosis. This review presents an overview of the molecular mechanisms of TGF-β/Smad signaling pathway in renal, hepatic, pulmonary and cardiac fibrosis, followed by an in-depth discussion of their molecular mechanisms of intervention effects both in vitro and in vivo. The role of TGF-β/Smad signaling pathway in tumor or cancer is also discussed. Additionally, the current advances also highlight targeting TGF-β/Smad signaling pathway for the prevention of tissue fibrosis. The review reveals comprehensive pathophysiological mechanisms of tissue fibrosis. Particular challenges are presented and placed within the context of future applications against tissue fibrosis.

The intervention effect of zuogui pill on chronic kidney disease-mineral and bone disorder regulatory factor

Chronic kidney disease-mineral and bone disorder (CKD-MBD) play a critical role in the pathogenesis of cardiovascular complications in patients with chronic kidney disease (CKD). Zuogui pill as a traditional Chinese herbal drug has been used for nourish kidney essence improve bone malnutrition of renal bone disease by regulating the metabolism of calcium and phosphorus and participating in osteoblast metabolism. In the present study, 5/6 nephrectomy rat model was used to reveal the mechanism of zuogui pill in treatment of CKD-MBD. Compared with sham rats, the levels of serum phosphorus, PTH, iPTH and creatinine were significantly decreased, while the serum calcium level was significantly increased, and the Cbfa1 protein level was significantly decreased and FGF23 protein level was significantly increased by Zuogui pill treatment. Compared with model rats, the BMD of rat was significantly increased by Zuogui pill treatment. Histological analysis revealed that the kidney injury of rats with CKD was significantly reduced by zuogui pill treatment. Compared with model rats, the CYP27B1 mRNA level was significantly increased, and the PTH mRNA level and NaPiIIa protein level were significantly decreased in the kidney by zuogui pill treatment. We inferred that zuogui pill exhibited potential therapeutic effects on CKD-MBD in the rats by regulating bone metabolism and nourish kidney.

Silence of IGFBP7 suppresses apoptosis and epithelial mesenchymal transformation of high glucose induced-podocytes

Insulin-like growth factor-binding protein 7 (IGFBP7) has been identified as a secreted protein associated with a number of cellular processes. However, the specific regulatory mechanisms of IGFBP7 on podocytes of diabetic nephropathy (DN) are yet to be elucidated. In the present study, podocytes were identified initially via an immunofluorescence assay using an anti-synaptopodin antibody. It was subsequently demonstrated that glucose promoted podocyte proliferation in a time- and dose-dependent manner via MTT assay. In addition, IGFBP7 expression was silenced in podocytes via siRNA, the effects of which were evaluated using western blotting and reverse transcription-quantitative polymerase chain reaction. It was demonstrated that silencing IGFBP7 inhibited apoptosis and epithelial mesenchymal transformation (EMT) of podocytes mediated by high glucose (HG). Transforming growth factor (TGF)-β1/mothers against decapentaplegic homolog (Smad) signaling was associated with proliferation, apoptotic activities and EMT. Therefore, the expression levels of TGF-β1/Smad pathway were detected, and it was observed that silencing IGFBP7 suppressed the TGF-β1/Smad pathway in podocytes induced by HG. These findings suggested that IGFBP7 may serve as a potential therapeutic target for DN.