Proteomic analysis of urine reveals biomarkers for the diagnosis and phenotyping of abdominal-type Henoch-Schonlein purpura

[Exploring the mechanism of IgA vasculitis pathogenesis through the interaction of thrombin and inflammatory factors using urinary proteomics]

OBJECTIVES

To explore the evidence, urinary biomarkers, and partial mechanisms of hypercoagulability in the pathogenesis of IgA vasculitis (IgAV).

METHODS

Differential expression of proteins in the urine of 10 healthy children and 10 children with IgAV was screened using high-performance liquid chromatography-tandem mass spectrometry, followed by Reactome pathway analysis. Protein-protein interaction (PPI) network analysis was conducted using STRING and Cytoscape software. In the validation cohort, 15 healthy children and 25 children with IgAV were included, and the expression levels of differential urinary proteins were verified using enzyme-linked immunosorbent assay.

RESULTS

A total of 772 differential proteins were identified between the IgAV group and the control group, with 768 upregulated and 4 downregulated. Reactome pathway enrichment results showed that neutrophil degranulation, platelet activation, and hemostasis pathways were involved in the pathogenesis of IgAV. Among the differential proteins, macrophage migration inhibitory factor (MIF) played a significant role in neutrophil degranulation and hemostasis, while thrombin was a key protein in platelet activation and hemostasis pathways. PPI analysis indicated that thrombin directly interacted with several proteins involved in inflammatory responses, and these interactions involved MIF. Validation results showed that compared to healthy children, children with IgAV had significantly higher urine thrombin/creatinine and urine MIF/creatinine levels (P<0.05).

CONCLUSIONS

Thrombin contributes to the pathogenesis of IgAV through interactions with inflammatory factors. Urinary thrombin and MIF can serve as biomarkers reflecting the hypercoagulable and inflammatory states in children with IgAV.

Plasma Proteomic Analysis Reveals the Potential Role of Lectin and Alternative Complement Pathways in IgA Vasculitis Pathogenesis

BACKGROUND

IgA vasculitis (IgAV) is the most common form of childhood vasculitis. A better understanding of its pathophysiology is required to identify new potential biomarkers and treatment targets.

OBJECTIVE

to assess the underlying molecular mechanisms in the pathogenesis of IgAV using an untargeted proteomics approach.

METHODS

Thirty-seven IgAV patients and five healthy controls were enrolled. Plasma samples were collected on the day of diagnosis before any treatment was initiated. We used nano-liquid chromatography-tandem mass spectrometry (nLC-MS/MS) to investigate the alterations in plasma proteomic profiles. For the bioinformatics analyses, databases including Uniprot, PANTHER, KEGG, Reactome, Cytoscape, and IntAct were used.

RESULTS

Among the 418 proteins identified in the nLC-MS/MS analysis, 20 had significantly different expressions in IgAV patients. Among them, 15 were upregulated and 5 were downregulated. According to the KEGG pathway and function classification analysis, complement and coagulation cascades were the most enriched pathways. GO analyses showed that the differentially expressed proteins were mainly involved in defense/immunity proteins and the metabolite interconversion enzyme family. We also investigated molecular interactions in the identified 20 proteins of IgAV patients. We extracted 493 interactions from the IntAct database for the 20 proteins and used Cytoscape for the network analyses.

CONCLUSION

Our results clearly suggest the role of the lectin and alternate complement pathways in IgAV. The proteins defined in the pathways of cell adhesion may serve as biomarkers. Further functional studies may lead the way to better understanding of the disease and new therapeutic options for IgAV treatment.

Dynamic urine proteome changes in a rat model of simvastatin-induced skeletal muscle injury

Statin-associated muscle symptoms (SAMS) are the main side effects of statins. Currently, there are no effective biomarkers for accurate clinical diagnosis. Urine is not subject to homeostatic control and therefore accumulates early changes, making it an ideal biomarker source. We therefore examined urine proteome changes associated with SAMS. Here, we established a SAMS rat model by intragastric intubation with simvastatin (80 mg/kg). Biochemical analyses and hematoxylin and eosin staining were used to evaluate the degree of muscle injury. The urine proteome on days 3, 6, 9 and 14 was profiled using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Differential proteins on day 14 of SAMS were mainly associated with glycolysis/gluconeogenesis, pyruvate metabolism, metabolism of reactive oxygen species and apoptosis, which were associated with the pathological mechanism of SAMS. Among the 14 differential proteins on day 3, Fibrinogen gamma chain (FIBG), Osteopontin (OSTP) and C-reactive protein (CRP) were associated with muscle damage, while EH domain-containing protein 1(EHD1), Cubilin (CUBN) and Fibronectin (FINC) were associated with the pathogenic mechanisms of SAMS. Our preliminary results indicated that the urine proteome can reflect early changes in the SAMS rat model, providing the potential for monitoring drug side effects in future clinical research. SIGNIFICANCE: This study demonstrate that the early muscle damage caused by simvastatin can be reflected in urinary proteins. The urine proteome also has the potential to reflect the pharmacology and toxicology of drugs in future clinical research.

Impact of the Glycemic Level on the Salivary Proteome of Middle-Aged and Elderly People With Type 2 Diabetes Mellitus: An Observational Study

Type 2 diabetes mellitus (T2DM) is an increasing global public health concern, but its impact on the salivary proteome is still unclear. To evaluate the effect of glycemic levels in middle-aged and elderly individuals with T2DM on salivary proteomics, we compared the differences by liquid chromatography tandem mass spectrometry (LC–MS/MS). Unstimulated whole saliva samples from 8 T2DM patients with good glycemic control (G group, HbA1c <6.5%) and 16 patients with poor control (P group, HbA1c ≥6.5%) were analyzed by LC–MS/MS in the data-independent acquisition mode (Clinical register number: ChiCTR1900023582.). After functional annotation, cluster analysis and receiver operating characteristic (ROC) curve analysis were carried out to screen and evaluate candidate proteins. A total of 5,721 proteins were quantified, while 40 proteins differed significantly. In the P group, proteins involved in oxidative stress-related processes were upregulated, whereas proteins related to salivary secretion were downregulated. The combination of thioredoxin domain-containing protein 17, zymogen granule protein 16B, and FAM3 metabolism regulating signaling molecule D yielded an area under the curve of 0.917 which showed a robust ability to distinguish the P and G groups. In conclusion, poorly controlled hyperglycemia may affect salivary proteins through various pathways, including oxidative stress and glandular secretion. Furthermore, the differentially expressed proteins, especially the three proteins with the best differentiation, might serve as an anchor point for the further study of hyperglycemia and oral diseases.