Increased plasma matrix metalloproteinase-2 (MMP-2), tissue inhibitor of proteinase-1 (TIMP-1), TIMP-2, and urine MMP-2 concentrations correlate with proteinuria in renal transplant recipients

The association between activation of the ERK1/2-NF-κB signaling pathway by TIMP2 expression and chronic renal allograft dysfunction in the CRAD rat model

PURPOSE

The tissue inhibitor of metalloproteinase 2 (TIMP2), a natural inhibitor of matrix metalloproteinase (MMP), regulates inflammation, fibrosis, and cell proliferation. Chronic renal allograft dysfunction (CRAD) is a primary factor affecting the long-term survival of renal allografts. We assessed whether up-regulation of TIMP2 expression may affect the ERK1/2-NF-κB signaling pathway and CRAD development.

METHODS

Lewis rats received orthotopic F344 kidney allografts to establish the classical CRAD model. The treatment group was injected with a lentivirus encoding a TIMP2-targeting small hairpin (sh)RNA (LTS) at 5 × 108 TU/ml monthly after kidney transplantation. A second CRAD group was injected with a lentivirus TIMP2-control vector (LTC). After 12 weeks, blood, urine, and kidney tissue were harvested to evaluate renal function and pathological examinations. Hematoxylin and eosin staining, Masson staining, and Periodic acid-Schiff staining were performed for renal histopathological evaluation according to the Banff criteria. TIMP2, phospho (p)-ERK1/2, p-p65 (NF-κB) expression levels were measured via immunohistochemical and Western blot analyses.

RESULTS

Compared to the F344 and Lewis control groups, the expression of TIMP2, p-ERK1/2, and p-p65 were significantly higher in the CRAD and CRAD+LTC renal tissues (p < 0.05). There were also increased levels of serum creatinine, nitrogen, and 24 h urinary protein in these two groups (p < 0.05). Typical histopathological changes of CRAD were observed in the CRAD and CRAD+LTC groups. Administration of LTS effectively decreased the expression of TIMP2, p-ERK1/2, and p-P65, and reduced interstitial fibrosis and macrophage infiltration in the treatment group (p < 0.05). Additionally, MCP1 and ICAM-1, which are downstream cytokines of the NF-κB pathway, were also inhibited in the renal rat kidney from the LTS group (p < 0.05). Furthermore, renal function was well preserved in the LTS group compared to the CRAD group and CRAD+LTC group.

CONCLUSION

A decrease of TIMP2 can alleviate the progression of inflammation in CRAD via inhibition of the ERK1/2-NF-κB signaling pathway.

Biomarkers in Primary Focal Segmental Glomerulosclerosis in Optimal Diagnostic-Therapeutic Strategy

Focal segmental glomerulosclerosis (FSGS) involves podocyte injury. In patients with nephrotic syndrome, progression to end-stage renal disease often occurs over the course of 5 to 10 years. The diagnosis is based on a renal biopsy. It is presumed that primary FSGS is caused by an unknown plasma factor that might be responsible for the recurrence of FSGS after kidney transplantation. The nature of circulating permeability factors is not explained and particular biological molecules responsible for inducing FSGS are still unknown. Several substances have been proposed as potential circulating factors such as soluble urokinase-type plasminogen activator receptor (suPAR) and cardiolipin-like-cytokine 1 (CLC-1). Many studies have also attempted to establish which molecules are related to podocyte injury in the pathogenesis of FSGS such as plasminogen activator inhibitor type-1 (PAI-1), angiotensin II type 1 receptors (AT1R), dystroglycan(DG), microRNAs, metalloproteinases (MMPs), forkheadbox P3 (FOXP3), and poly-ADP-ribose polymerase-1 (PARP1). Some biomarkers have also been studied in the context of kidney tissue damage progression: transforming growth factor-beta (TGF-β), human neutrophil gelatinase-associated lipocalin (NGAL), malondialdehyde (MDA), and others. This paper describes molecules that could potentially be considered as circulating factors causing primary FSGS.

Association between urinary biomarkers MMP-7/TIMP-2 and reduced renal function in children with ureteropelvic junction obstruction

IMPORTANCE

Extracellular matrix proteins and enzymes involved in degradation have been found to be associated with tissue fibrosis and ureteropelvic junction obstruction (UPJO). In this study we developed a promising urinary biomarker model which can identify reduced renal function in UPJ obstruction patients. This can potentially serve as a non-invasive way to enhance surgical decision making for patients and urologists.

OBJECTIVE

We sought to develop a predictive model to identify UPJO patients at risk for reduced renal function.

DESIGN

Prospective cohort study.

SETTING

Pre-operative urine samples were collected in a prospectively enrolled UPJO biomarker registry at our institution. Urinary MMP-2, MMP-7, TIMP-2, and NGAL were measured as well as clinical characteristics including hydronephrosis grade, differential renal function, t1/2, and UPJO etiology.

PARTICIPANTS

Children who underwent pyeloplasty for UPJO.

MAIN OUTCOME MEASUREMENT

Primary outcome was reduced renal function defined as MAG3 function <40%. Multivariable logistic regression was applied to identify the independent predictive biomarkers in the original Training cohort. Model validation and generalizability were evaluated in a new UPJO Testing cohort.

RESULTS

We included 71 patients with UPJO in the original training cohort and 39 in the validation cohort. Median age was 3.3 years (70% male). By univariate analysis, reduced renal function was associated with higher MMP-2 (p = 0.064), MMP-7 (p = 0.047), NGAL (p = 0.001), and lower TIMP-2 (p = 0.033). Combining MMP-7 with TIMP-2, the multivariable logistic regression model predicted reduced renal function with good performance (AUC = 0.830; 95% CI: 0.722-0.938). The independent testing dataset validated the results with good predictive performance (AUC = 0.738).

CONCLUSIONS AND RELEVANCE

Combination of urinary MMP-7 and TIMP-2 can identify reduced renal function in UPJO patients. With the high sensitivity cutoffs, patients can be categorized into high risk (aggressive management) versus lower risk (observation).

YAP1 promotes high glucose-induced inflammation and extracellular matrix deposition in glomerular mesangial cells by modulating NF-κB/JMJD3 pathway

Diabetic nephropathy (DN) is one of the most serious microvascular complications of late-stage diabetes. Glomerular mesangial cell (GMC) proliferation and excessive extracellular matrix (ECM) deposition are the main pathological characteristics associated with the occurrence and development of DN. Yes-associated protein 1 (YAP1) can bind to several transcription factors and is associated with the development of various diseases. However, the effects of YAP1 on DN remain unclear. The aim of the present study was to explore the regulatory effect and potential mechanism of YAP1 in glucose-induced inflammation and ECM deposition in high-glucose-treated GMCs. In the present study, HBZY-1 cell models treated with high glucose were constructed, and the effects of YAP1 on the proliferation, inflammation, ECM deposition and fibrosis of HBZY-1 cells were detected. The results showed that YAP1 was highly expressed in HBZY-1 cells treated with high glucose and that YAP1 silencing decreased cell viability, the levels of inflammatory cytokines, ECM deposition and the degree of fibrosis in cells. Further experiments revealed that NF-κB/Jumonji domain-containing protein D3 (JMJD3) signaling pathway inhibitors alleviated the promoting effect of YAP1 overexpression on inflammatory response and ECM deposition in HBZY-1 cells treated with high glucose. In conclusion, it was demonstrated that YAP1 can promote high glucose-induced inflammation and ECM deposition by activating the NF-κB/JMJD3 signaling pathway in GMCs.

MMP-9-mediated regulation of hypoxia-reperfusion injury-related neutrophil inflammation in an in vitro proximal tubular cell model

Background

Hypoxia-reperfusion (HR) and inflammation are causes of renal allograft injury. Pathological evidence has indicated that ischemia followed by reperfusion leads to the proteolysis and destruction of the extracellular matrix (ECM) in renal tubular epithelial cells. Matrix metalloproteinases (MMPs), such as MMP-2 and MMP-9, play roles in cleaving and reshaping the ECM. Acute accumulation of MMP-9 secreted from neutrophils promotes the incidence of inflammation and exacerbates graft trauma. Our goal was to investigate the activities of MMP-9/MMP-2 and their correlation with HR injury and neutrophil-related inflammation in renal proximal tubular cells.

Methods

This model was established by placing HK-2 cells under hypoxic conditions (5% CO₂, 1% O₂) for 6 h and then exposing them to reperfusion (5% CO₂, 21% O₂) for 12 h in a tri-gas incubator. The cell culture medium was collected for culturing polymorphonuclear leukocytes (PMNs). BB-94 (MMP-9 inhibitor) was added to the culture medium in the inhibitor group.

Results

Flow cytometry showed a significant increase in reactive oxygen species (ROS) levels in HK-2 cells from the HR injury group. MMP-9 expression was significantly increased and MMP-2 expression was significantly decreased in HK-2 cells from the HR group. MMP-9 and MPO expression were significantly increased in the HR group, while MPO expression was significantly decreased in the PMN inhibitor group.

Conclusions

The outcomes indicated that MMP-9 and MMP-2 are important components of an underlying pathophysiological mechanism of injury following HR. MMP-9 inhibition may be a potential approach to mitigateHR injury.

Impact of Matrix Metalloproteinases 2 and 9 and Tissue Inhibitor of Metalloproteinase 2 Gene Polymorphisms on Allograft Rejection in Pediatric Renal Transplant Recipients

OBJECTIVES

Acute and chronic allograft rejection have been continuously an important obstacle in the follow-up of renal transplant recipients. During clinical management, several factors acting simultaneously result in acute rejection and chronic allograft nephropathy. Matrix metalloproteinases and tissue inhibitors of metalloproteinases are responsible for the organization of the extracellular matrix and play roles in cell proliferation and cellular invasion. Changes in matrix metalloproteinase expression levels have been reported to be associated with renal allograft rejection and interstitial fibrosis. In this study, we aimed to investigate functional polymorphisms of MMP2, MMP9, and TIMP2 genes in pediatric renal transplant recipients.

MATERIALS AND METHODS

Our study included 68 kidney transplant recipients and 58 control patients. The kidney transplant recipient group was further divided into 2 subgroups: no graft rejection (n = 47) and graft rejection (n =21). MMP2 -735C >T (rs2285053), MMP2 -1306C >T (rs243865), MMP2 -1575G >A (rs243866), MMP9 c.-1562C >T (rs3918242), TIMP2 -418G >C (rs8179090), and TIMP2 303C > T (rs2277698) polymorphisms were analyzed with the use of polymerase chain reaction and restriction fragment-length polymorphism methods. Allele prevalence was compared with reference values of the control group, and Hardy-Weinberg equilibrium was tested.

RESULTS

Mean ages were 16.7 ± 3.9 years for the study group and 14.8 ± 5.6 years for the control group. The mean follow-up time after transplant was 37.7 ± 7.9 months. We compared allele frequencies in the 2 groups and calculated a statistically significant difference in rs2285053, rs243865, rs243866, rs3918242, rs8179090, and rs2277698 polymorphism frequencies between the transplant recipients and control patients. When the transplant recipient group was compared in itself with regard to allograft rejection, all investigated polymorphisms except TIMP2 -418G >C (rs8179090) revealed a statistically significant difference between those with and without rejection (P < .05).

CONCLUSIONS

Matrix metalloproteinases and their tissue inhibitors could be important predictive biological markers for the follow-up of kidney transplant recipients.

Disequilibrium in MMPs and the tissue inhibitor of metalloproteinases in different segments of the varicose great saphenous vein wall

BACKGROUND

Varicose great saphenous veins (VGSVs) are a common disorder with a high incidence, but the pathogenesis is unclear. This study was designed to measure the changes in matrix metalloproteinases (MMPs) and the tissue inhibitor of metalloproteinases (TIMPs) in different segments from VGSV walls to determine the relationship between MMPs, TIMPs expression, and expansion of the venous wall.

METHODS

Twenty-one VGSV and 12 normal great saphenous vein (GSV) specimens were collected. Venous walls in the two groups, expression of MMP-2, MMP-9, TIMP-1, and TIMP-2 proteins, protein-positive expression ratios, mRNA expression, and protein content were determined by immunohistochemistry, PCR, and western blot.

RESULTS

The MMP-2, MMP-9, TIMP-1, and TIMP-2 protein-positive expression ratios, mRNA expression in the upper, middle, and lower segments in the VGSV group were significantly higher than the corresponding regions in the GSV group, respectively. The MMP-2, MMP-9, TIMP-1, and TIMP-2 protein-positive expression ratios, mRNA expression, and protein concentrations in the lower segments in the VGSV group were also significantly higher than the upper and middle segments in the VGSV group and the corresponding regions in the GSV group, respectively.

CONCLUSIONS

Under high hemodynamics, disequilibrium of MMPs and TIMPs from VGSVs exists within the upper, middle, and lower segments of VGSVs. These results suggested that MMPs and TIMPs participate in the process of venous wall remodeling and may be one of the mechanisms associated with the formation and development in varicose veins.

Urinary IL-8 is a marker of early and long-term graft function after renal transplantation

In this study, we examined whether the IL-8 content of urine sampled on day 1 and day 14 after renal transplantation is a marker of early and long-term renal function. Moreover, we assessed whether its concentration is positively correlated with the matrix metalloproteinase-9 (MMP-9) content of urine sampled on day 1 and day 30 and 12 months after renal transplantation. Our analysis covered 87 patients who underwent a kidney transplant. The patients were observed for an average of 30 months (12-60 months). The IL-8 concentration determined on day 1 was significantly negatively correlated with creatinine clearance early after renal transplantation (on days 1, 7, 14 and 30), as well as during long-term observations. IL-8 concentration in urine sampled on day 1 and day 14 was higher in patients demonstrating DGF than in those without DGF. No relationship was found between IL-8 content and cold ischaemia time. MMP-9 activity determined on day 1 and month 3 after renal transplantation was positively correlated with the IL-8 content determined in urine sampled on day 1, Rs = +0.32, p < .05 and Rs = +0.31, p < .05, respectively. The results of this study suggest that a high IL-8 content in urine sampled on day 1 after renal transplantation is an unfavourable marker of early and long-term (years-long) graft function. A high IL-8 content in urine sampled on day 1 after renal transplantation was positively correlated with the activity of metalloproteinase-9 in urine. This proves that both of these chemokines cooperate in ischaemia-reperfusion injuries in transplanted kidneys.

Biomarkers in Acute Kidney Injury

Acute kidney injury (AKI) is a common and often lethal complication that is also associated with severe morbidity in hospitalized patients. During the last decade, the standardization of AKI diagnostic criteria has helped to facilitate several large-scale investigations of biomarkers of AKI. These studies have led to the international clinical implementation of several biomarkers of renal injury. This review summarizes the results of many of these multicenter investigations and discusses the clinical utility and interpretation of several of these new clinical tests. The merits of combining biomarkers of kidney function is also discussed.