iTRAQ-Based Comparative Proteomics Analysis of Urolithiasis Rats Induced by Ethylene Glycol

E53, E96, D162, E247 and D322 in Ca2+-binding domains of annexin A2 are essential for regulating intracellular [Ca2+] and crystal adhesion to renal cells via ERK1/2 and JNK signaling pathways

Annexin A2 (ANXA2) is expressed inside the cytoplasm and on the surface of renal tubular epithelial cells (RTECs) and is documented as a calcium oxalate monohydrate (COM) crystal-binding protein. Nevertheless, its molecular mechanism involved in kidney stone disease (KSD) remains underinvestigated. Herein, we performed various molecular assays to unravel the roles of ANXA2 and core residues (E53, E96, D162, E247 and D322) in its Ca2+-binding domains in the stone formation mechanism, particularly at crystal-cell adhesion step and downstream signaling cascade. ANXA2 was up-regulated in apical membranes, not cytosol, of RTECs after COM crystal exposure. Neutralizing the surface expression of ANXA2 by a specific monoclonal antibody and silencing its expression by small interfering RNA (siRNA) significantly decreased COM crystal-cell adhesion. siRNA also suppressed the COM-induced up-regulation of phospho-ERK1/2 and phospho-JNK, but not that of phospho-p38. Overexpression of ANXA2 wild-type (WT), but not that of E53A, E96A, D162A, E247A and D322A mutants of its Ca2+-binding domains, significantly increased intracellular [Ca2+], COM-cell adhesion, and phospho-ERK1/2 level. Therefore, E53, E96, D162, E247 and D322 in the Ca2+-binding domains of annexin A2 are essential for regulating intracellular [Ca2+] and COM crystal-cell adhesion via ERK1/2 and JNK signaling pathways.

Spaceflight causes strain-dependent gene expression changes in the kidneys of mice

Incidence of kidney stones in astronauts is a major risk factor associated with long-term missions, caused by increased blood calcium levels due to bone demineralisation triggered by microgravity and space radiation. Transcriptomic changes have been observed in tissues during spaceflight, including the kidney. We analysed kidney transcriptome patterns in two different strains of mice flown on the International Space Station, C57BL/6J and BALB/c. Here we show a link between spaceflight and transcriptome patterns associated with dysregulation of lipid and extracellular matrix metabolism and altered transforming growth factor-beta signalling. A stronger response was seen in C57BL/6J mice than BALB/c. Genetic differences in hyaluronan metabolism between strains may confer protection against extracellular matrix remodelling through the downregulation of epithelial-mesenchymal transition. We intend for our findings to contribute to the development of new countermeasures against kidney disease in astronauts and people here on Earth.

Inverse association between prognostic nutritional index and kidney stone prevalence: A population-based study

BACKGROUND

Kidney stones frequently occur due to metabolic disorders, dietary habits, and lifestyle influences. The Prognostic Nutritional Index, which reflects an individual's nutritional condition, might be associated with kidney stone prevalence. This study examines the association between PNI and kidney stone prevalence in US adults.

METHODS

The study used data from the National Health and Nutrition Examination Survey database from 2009-2018 and excluded pregnant women, and individuals who lacked data on kidney stones, or had incomplete Prognostic Nutritional Index data. Independent associations between Prognostic Nutritional Index and kidney stones were investigated by multivariate logistic regression and subgroup analyses, in addition to exploring nonlinear associations using smoothed curves and threshold effects.

RESULTS

A total of 13,835 participants aged ≥ 20 years were included, with a kidney stone prevalence of 8.48%. An inverse association was observed between the Prognostic Nutritional Index and kidney stone prevalence (OR =  0.97, 95% CI =  0.96-0.98, P <  0.001). This relationship was not significantly modified by race, education, marital status, or comorbidities such as hypertension, diabetes, and hyperlipidemia. However, sex and total cholesterol levels influenced the association. Stratified analysis showed a significant negative association in men (OR =  0.98, 95% CI =  0.96-0.99, P =  0.031), but not in women. A nonlinear relationship was identified in individuals with total cholesterol ≥  5.2 mmol/L, with a significant negative association below the inflection point of 57 (OR =  0.96, P =  0.012) and a positive association above it (OR =  1.11, P =  0.03). These findings suggest that the Prognostic Nutritional Index is inversely associated with kidney stones, particularly in men and those with high cholesterol levels.

CONCLUSION

The Prognostic Nutritional Index was negatively associated with the risk of kidney stones, particularly in men and individuals with high cholesterol levels below the identified inflection point, suggesting that tailored nutritional management may be crucial for these subgroups.

Peripheral serum iTRAQ-based proteomic characteristics of carbon tetrachloride-induced acute liver injury in Macaca fascicularis

Carbon tetrachloride (CCl4) is a potent chemical compound that can induce liver cells necrosis. The purpose of this study was to evaluate the hepatic toxicity of CCl4 exposure in Macaca fascicularis to explore the liver toxicity mechanism using a proteomic approach. One animal (no.F6) was intoxicated by oral gavage with 15 % CCl4 solution (10 mL/kg, dissolved in edible peanut oil), and was sacrificed at 48 h after CCl4 administration. Another blank control animal (no.F4) was sacrificed at the same time. The liver cells of the blank control animal showed normal hepatocyte morphology. However, the hepatocytes at 48 h time point after CCl4 administration showed necrosis and vacuolation histopathologically. The animal No.F7∼F12 and no.M7∼M12 were administrated by gavage with 15 % CCl4 solution (10 mL/kg, dissolved in edible peanut oil). Blood samples were collected before gavage administration, and served as the 0 h blank control samples. Then, blood samples were collected at 2 h, 48 h, 72 h and 168 h after CCl4 exposure, and served as the test samples. Routine biochemistry and immunical parameters were performed using biochemistry analyzer for all serum. Then the serum from male and female animals at 0 h, 2 h, 48 h, and 72 h was mixed, respectively. The peripheral serum proteins at 0 h, 2 h, 48 h, and 72 h were extracted, then the proteins were enzymatically hydrolyzed and the peptides were isotopic labeled by isobaric tags for relative and absolute quantification (iTRAQ). Finally, the UniProt Protein Sequence Library of Macaca fascicularis was queried to identify and compare the differential proteins between different time points. The results showed that, as traditional biomarkers of liver injury, alanine aminotransferases (ALT) and aspartate aminotransferases (AST) showed a typical time-effect curve. Compared with 0 h, there were totally 55, 323, and 158 differential proteins (P value <0.05, Ratio fold >1.5, FDR<0.05) at 2 h, 48 h and 72 h, respectively. GO enrichment analysis of differentially expressed proteins only at 48 h involved 3 cellular components (P adjust value <0.05), and differential proteins at other time points had no significant enrichment. Furthermore, KEGG enrichment analysis showed that the toxicity effect of CCl4 at different time points after administration was mediated through 22 pathways such as biosynthesis of antibiotics, carbon metabolism, biosynthesis of amino acids, peroxisome, cysteine and methionine metabolism, arginine biosynthesis, and complement and coagulation cascades (P adjust value <0.05). Among them, the counts of signaling pathway involved biosynthesis of antibiotics, carbon metabolism and biosynthesis of amino acids were more than 10 and the three pathways may play a greater role in toxicity progress after administration of CCl4. PPI network analysis showed that there were 3, 52, and 13 nodes in the interaction of differential proteins at 2 h, 48 h, and 72 h, respectively. In conclusion, many differential proteins in peripheral blood were detected after CCl4 administration, and the GO and KEGG enrichment analysis showed the toxicological mechanisms of CCl4-induced liver injury and potential protection reaction mechanism for CCl4 detoxication may be related with multi biological processes, signaling pathway and targets.

Spaceflight causes strain dependent gene expression changes associated with lipid and extracellular matrix dysregulation in the mouse kidney in vivo

To explore new worlds we must ensure humans can survive and thrive in the space environment. Incidence of kidney stones in astronauts is a major risk factor associated with long term missions, caused by increased blood calcium levels due to bone demineralisation triggered by microgravity and space radiation. Transcriptomic changes have been observed in other tissues during spaceflight, including the kidney. We analysed kidney transcriptome patterns in two different strains of mice flown on the International Space Station, C57BL/6J and BALB/c. Here we show a link between spaceflight and transcriptome patterns associated with dysregulation of lipid and extracellular matrix metabolism and altered transforming growth factor-beta signalling. A stronger response was seen in C57BL/6J mice than BALB/c. Genetic differences in hyaluronan metabolism between strains may confer protection against extracellular matrix remodelling through downregulation of epithelial-mesenchymal transition. We intend for our findings to contribute to development of new countermeasures against kidney disease in astronauts and people here on Earth.

Combined metabolomic and proteomic analysis of sepsis related acute liver injury and its pathogenesis research

BACKGROUND

Sepsis-induced acute liver injury is common in patients in intensive care units. However, the exact mechanism of this condition remains unclear. The purpose of this study was to investigate the roles and mechanisms of proteins and metabolites in the liver tissue of mice after sepsis and elucidate the molecular biological mechanisms of sepsis-related liver injury.

METHODS

First, a lipopolysaccharide (LPS)-induced sepsis mouse model was established. Then, according to alanine aminotransferase (ALT) and aspartate aminotransferase (AST) detection in mouse serum and liver histopathological examination (HE) staining, the septic mice were divided into two groups: acute liver injury after sepsis and nonacute liver injury after sepsis. Metabolomics and proteomic analyses were performed on the liver tissues of the two groups of mice to identify significantly different metabolites and proteins. The metabolomics and proteomics results were further analysed to identify the biological indicators and pathogenesis related to the occurrence and development of sepsis-related acute liver injury at the protein and metabolite levels.

RESULTS

A total of 14 differentially expressed proteins and 46 differentially expressed metabolites were identified. Recombinant Erythrocyte Membrane Protein Band 4.2 (Epb42) and adenosine diphosphate (ADP) may be the key proteins and metabolites responsible for sepsis-related acute liver injury, according to the correlation analysis of proteomics and metabolomics. The expression of the differential protein Epb42 was further verified by western blot (WB) detection.

CONCLUSIONS

Our study suggests that the differential protein Epb42 may be key proteins causing sepsis-associated acute liver injury, providing new and valuable information on the possible mechanism of sepsis-associated acute liver injury.

Identification of the key immune-related genes and immune cell infiltration changes in renal interstitial fibrosis

Background

Chronic kidney disease (CKD) is the third-leading cause of premature mortality worldwide. It is characterized by rapid deterioration due to renal interstitial fibrosis (RIF) via excessive inflammatory infiltration. The aim of this study was to discover key immune-related genes (IRGs) to provide valuable insights and therapeutic targets for RIF in CKD.

Materials and methods

We screened differentially expressed genes (DEGs) between RIF samples from CKD patients and healthy controls from a public database. Least absolute shrinkage and selection operator regression analysis and receiver operating characteristic curve analysis were applied to identify significant key biomarkers. The single-sample Gene Set Enrichment Analysis (ssGSEA) algorithm was used to analyze the infiltration of immune cells between the RIF and control samples. The correlation between biomarkers and immune cell composition was assessed.

Results

A total of 928 DEGs between CKD and control samples from six microarray datasets were found, 17 overlapping immune-correlated DEGs were identified by integration with the ImmPort database, and six IRGs were finally identified in the model: apolipoprotein H (APOH), epidermal growth factor (EGF), lactotransferrin (LTF), lysozyme (LYZ), phospholipid transfer protein (PLTP), and secretory leukocyte peptidase inhibitor (SLPI). Two additional datasets and in vivo experiments indicated that the expression levels of APOH and EGF in the fibrosis group were significantly lower than those in the control group, while the expression levels of LTF, LYZ, PLTP, and SLPI were higher (all P < 0.05). These IRGs also showed a significant correlation with renal function impairment. Moreover, four upregulated IRGs were positively associated with various T cell populations, which were enriched in RIF tissues, whereas two downregulated IRGs had opposite results. Several signaling pathways, such as the "T cell receptor signaling pathway" and "positive regulation of NF-κB signaling pathway", were discovered to be associated not only with immune cell infiltration, but also with the expression levels of six IRGs.

Conclusion

In summary, six IRGs were identified as key biomarkers for RIF, and exhibited a strong correlation with various T cells and with the NF-κB signaling pathway. All these IRGs and their signaling pathways may evolve as valuable therapeutic targets for RIF in CKD.

Integrated single-nucleus sequencing and spatial architecture analysis identified distinct injured-proximal tubular types in calculi rats

BACKGROUND

Urolithiasis with high prevalence and recurrence rate, has impacts on kidney injury in patients, becomes a socioeconomic and healthcare problem in worldwide. However, the biology of kidney with crystal formation and proximal tubular injury remains essentially unclear. The present study aims to evaluate the cell biology and immune-communications in urolithiasis mediated kidney injury, to provide new insights in the kidney stone treatment and prevention.

RESULTS

We identified 3 distinct injured-proximal tubular cell types based on the differentially expression injury markers (Havcr1 and lcn2) and functional solute carriers (slc34a3, slc22a8, slc38a3 and slc7a13), and characterized 4 main immune cell types in kidney and one undefined cell population, where F13a1^+/high/CD163^+/high monocyte & macrophage and Sirpa/Fcgr1a/Fcgr2a^+/high granulocyte were the most enriched. We performed intercellular crosstalk analysis based on the snRNA-seq data and explored the potential immunomodulation of calculi stone formation, and founded that the interaction between ligand Gas6 and its receptors (Gas6-Axl, Gas6-Mertk) was specifically observed in the injured-PT1 cells, but not injured-PT2 and -PT3 cells. The interaction of Ptn-Plxnb2 was only observed between the injured-PT3 cells and its receptor enriched cells.

CONCLUSIONS

Present study comprehensively characterized the gene expression profile in the calculi rat kidney at single nucleus level, identified novel marker genes for all cell types of rat kidney, and determined 3 distinct sub-population of injured-PT clusters, as well as intercellular communication between injured-PTs and immune cells. Our collection of data provides a reliable resource and reference for studies on renal cell biology and kidney disease.