Raised concentrations of the carboxy terminal propeptide of type IV (basement membrane) procollagen (NC1) in serum and urine of patients with glomerulonephritis

The basement membrane in the cross-roads between the lung and kidney

The basement membrane (BM) is a specialized layer of extracellular matrix components that plays a central role in maintaining lung and kidney functions. Although the composition of the BM is usually tissue specific, the lung and the kidney preferentially use similar BM components. Unsurprisingly, diseases with BM defects often have severe pulmonary or renal manifestations, sometimes both. Excessive remodeling of the BM, which is a hallmark of both inflammatory and fibrosing diseases in the lung and the kidney, can lead to the release of BM-derived matrikines, proteolytic fragments with distinct biological functions. These matrikines can then influence disease activity at the site of liberation. However, they are also released to the circulation, where they can directly affect the vascular endothelium or target other organs, leading to extrapulmonary or extrarenal manifestations. In this review, we will summarize the current knowledge of the composition and function of the BM and its matrikines in health and disease, both in the lung and in the kidney. By comparison, we will highlight, why the BM and its matrikines may be central in establishing a renal-pulmonary interaction axis.

Anti-angiogenic collagen fragment arresten is increased from 16 weeks' gestation in pre-eclamptic plasma

INTRODUCTION

Arresten and canstatin are endogenous anti-angiogenic factors derived from type IV collagen α-chains COL4A1 and COL4A2 respectively. While their functions are explored in cancer studies, little is known about their role in pregnancy. Pre-eclampsia (PE) is a common, serious hypertensive disorder of pregnancy that is characterised by systemic endothelial dysfunction. COL4A1 and COL4A2 are maternal PE susceptibility genes that have increased mRNA expression in PE decidua. Our study aim was to determine the levels of arresten and canstatin in plasma and decidua from PE and gestational age matched normotensive patients.

METHODS

Plasma was collected from normotensive (n = 44) and PE (n = 39) women during the second and third trimesters of pregnancy. Third trimester decidua was collected at delivery from normotensive and PE women (n = 4 each). Levels of arresten and canstatin were determined by Western immunoblotting.

RESULTS

Arresten levels were significantly increased in second and third trimester PE plasma, and in third trimester PE decidua (p < 0.05). Third trimester PE plasma arresten levels also significantly correlated with the need for MgSO4 treatment, where a 1.7 fold increase was observed in patients requiring MgSO4 treatment (p < 0.05). No significant change in canstatin levels was observed between normotensive and PE patients.

DISCUSSION

This is the first study to report significant increases in the levels of collagen fragment arresten in PE plasma and decidua. Given its significant increase before the onset of clinical disease and associations with clinical severity in the third trimester, arresten may be a useful biomarker for predicting PE and monitoring its severity.

Serum and urinary procollagen III aminoterminal propeptide as a biomarker of obstructive nephropathy in children

BACKGROUND

Ureteropelvic junction obstruction (UPJO) is the most common cause of chronic renal failure in children. Rapid diagnosis is important to preserve function and/or to slow down renal injury. This study was to examine serum and urinary procollagen III aminoterminal propeptide (sPIIINP/uPIIINP) protein as potential biomarkers of obstruction in hydronephrosis.

METHODS

The study included 29 children with unilateral UPJO who underwent pyeloplasty (Group 1), 30 children with mild, nonobstructive hydronephrosis (Group 2), and 30 healthy children. In Group 1, serum and voided urine samples were obtained at preoperative, 3 days, and 3, 6 and 12 months after pyeloplasty, respectively. Meanwhile, additional urine from the affected pelvis was collected at surgery. Serum and voided urine were evaluated for PIIINP in each group using immunoenzymatic enzyme-linked immunosorbent assay (ELISA) commercial kits and were expressed in picograms per milligram creatine (cr.).

RESULTS

The preoperative sPIIINP and uPIIINP levels were significantly greater in Group 1 than in other 2 groups. Three months after pyeloplasty, sPIIINP and uPIIINP levels had decreased significantly in Group 1 together with significant improvement of split renal function. Receiver operator characteristic (ROC) analyses revealed a good diagnostic profile for uPIIINP/cr. in identifying children with abnormal split renal function (<40%) [area under the curve (AUC) 0.789].

CONCLUSIONS

Increasing uPIIINP levels are associated with worsening obstruction. Additional studies are required to confirm a potential application uPIIINP as a useful biomarker for the diagnosis and progression of congenital obstructive nephropathy.

Association of systemic collagen type IV formation with survival among patients undergoing hemodialysis

OBJECTIVE

The 7S domain of collagen type IV (P4NP_7S) assessed in plasma represents systemic collagen type IV formation. The objective of the study was to investigate the association of systemic collagen type IV formation with survival among patients undergoing hemodialysis.

METHODS

We performed an observational cohort study of 371 hemodialysis patients. Plasma P4NP_7S was analyzed using a specific enzyme-linked immunosorbent assay detecting the amino-terminal propeptide of type IV procollagen. Association between categories of plasma P4NP_7S concentrations and survival was initially assessed by Kaplan-Meier analysis, then in an adjusted Cox model.

RESULTS

For hemodialysis patients in the highest category of systemic collagen type IV formation, i.e. plasma P4NP_7S concentrations more than 775 pg/L, an increased risk for death was observed (highest P4NP_7S category vs all other categories, hazard ratio, 1.934; 95% confidence interval, 1.139 to 3.285). Survival analysis showed an increased risk of death in the highest P4NP_7S category compared to the other categories (Chi square 6.903; P = 0.032). Median survival was only 105 days in the highest P4NP_7S category whereas it was 629 days in the medium category, and 905 days in the lowest category. Multivariable-adjusted Cox regression showed increased odds for death with higher age and higher P4NP_7S categories. Systemic collagen type IV formation was associated with plasma concentrations of the collagen IV degradation product C4M (Spearman r = 0.764; P<0.0001) confirming extracellular matrix turnover.

CONCLUSION

Among hemodialysis patients elevated systemic collagen type IV formation suggesting accelerating systemic fibrosis was associated with increased risk of death.

Integrative urinary peptidomics in renal transplantation identifies biomarkers for acute rejection

Noninvasive methods to diagnose rejection of renal allografts are unavailable. Mass spectrometry followed by multiple-reaction monitoring provides a unique approach to identify disease-specific urine peptide biomarkers. Here, we performed urine peptidomic analysis of 70 unique samples from 50 renal transplant patients and 20 controls (n = 20), identifying a specific panel of 40 peptides for acute rejection (AR). Peptide sequencing revealed suggestive mechanisms of graft injury with roles for proteolytic degradation of uromodulin (UMOD) and several collagens, including COL1A2 and COL3A1. The 40-peptide panel discriminated AR in training (n = 46) and test (n = 24) sets (area under ROC curve >0.96). Integrative analysis of transcriptional signals from paired renal transplant biopsies, matched with the urine samples, revealed coordinated transcriptional changes for the corresponding genes in addition to dysregulation of extracellular matrix proteins in AR (MMP-7, SERPING1, and TIMP1). Quantitative PCR on an independent set of 34 transplant biopsies with and without AR validated coordinated changes in expression for the corresponding genes in rejection tissue. A six-gene biomarker panel (COL1A2, COL3A1, UMOD, MMP-7, SERPING1, TIMP1) classified AR with high specificity and sensitivity (area under ROC curve = 0.98). These data suggest that changes in collagen remodeling characterize AR and that detection of the corresponding proteolytic degradation products in urine provides a noninvasive diagnostic approach.

Decreased urinary concentrations of type IV collagen in amyotrophic lateral sclerosis

OBJECTIVES

Type IV collagen (IV-C) abnormalities of skin and serum have been reported in patients with amyotrophic lateral sclerosis (ALS). However, there has been no study of urinary IV-C in ALS. The present study investigates urinary IV-C and the relation to its skin content in patients with ALS.

MATERIAL AND METHODS

We studied IV-C immunoreactivity of skin and measured urinary levels of IV-C in ALS patients and controls.

RESULTS

The basement membrane as well as blood vessels of skin in ALS patients was weakly positive for IV-C as compared with those of controls. Immunostaining became even weaker as ALS progressed. The urinary level of IV-C in ALS patients was significantly decreased as compared to diseased controls (P<0.001) and healthy controls (P<0.001), and was negatively and significantly associated with duration of symptoms (r=-0.85, P<0.001). There was an appreciable positive correlation between urinary IV-C levels and the density for IV-C immunoreactivity in ALS patients (r=0.84, P<0.01).

CONCLUSION

These data suggest that a metabolic alteration of IV-C may occur in ALS patients and decreased levels of urinary IV-C may be related to the decreased IV-C immunoreactivity of skin in ALS.

Urinary type IV collagen as a marker for early diabetic nephropathy

We investigated the urinary secretion of type IV collagen in 115 subjects with non-insulin-dependent diabetes mellitus (NIDDM) without macroproteinuria, 34 normal healthy subjects and 19 subjects with chronic glomerulonephritis (CGN). We examined the relation between the urinary level of type IV collagen and various clinical parameters. The urinary level of type IV collagen was significantly elevated in NIDDM subjects compared with normal subjects (4.88 +/- 3.12 vs. 1.7 +/- 1.25 micrograms/gCr, P < 0.001). The urinary level of type IV collagen was increased even in NIDDM subjects with normoalbuminuria. The ratio of urinary type IV collagen was significantly lower in subjects with chronic glomerulonephritis (CGN) than those in NIDDM subjects (P < 0.001), although there was no significant difference in the urinary level of type IV collagen between NIDDM and CGN subjects. The ratio of urinary type IV collagen to albumin was under 10.0 x 10(-6) in all subjects with CGN. Our results suggest that measurement of the urinary level of type IV collagen is useful for detection of early diabetic nephropathy and for the differential diagnosis of diabetic nephropathy and chronic glomerulonephritis.

Urinary excretion of type IV collagen and laminin in the evaluation of nephropathy in NIDDM: comparison with urinary albumin and markers of tubular dysfunction and/or damage

To clarify the diagnostic relevance of urinary type IV collagen (IV-C) and laminin in diabetic nephropathy, the excretion of these basement membrane proteins were determined by enzyme immunoassay in 172 non-insulin-dependent diabetic patients with different grades of nephropathy and 64 non-diabetic control subjects, and were evaluated in comparison with those of urinary albumin, N-acetyl-beta-D-glucosaminidase (NAG) and alpha 1-microglobulin (alpha 1MG). These excretions were also compared between a group of non-diabetic renal disease (NDRD) patients (n = 24) and a subgroup of the diabetic patients studied (n = 76), whose urinary albumin excretion (UAE) varied within the ranges of micro- and macroalbuminuria. Of the diabetic patients studied, 49.7%, 53.4% and 32.4% had raised urinary albumin, NAG and alpha 1 MG excretion, respectively. In these patients, 54% and 53% exceeded the upper limit of normal for urinary IV-C and laminin. The level of IV-C and laminin excretion and the prevalence of their abnormal excretion showed a trend to increase with increasing grade of nephropathy, as assessed by UAE. In the normoalbuminuric [UAE < 20 mg/g creatinine (Cr)] stage, 28.3% and 26.3% patients had raised urinary IV-C and laminin excretion, respectively. In this stage, the excretion values for IV-C and laminin also rose significantly even when the UAE was < or = 10 mg/g Cr (P < 0.05 and P < 0.005, respectively). There was a close linear relationship between IV-C and laminin excretion (r = 0.73, P < 0.0001), together with their significant relationships with albumin, NAG and alpha 1MG excretion. The relationship of urinary IV-C and laminin with urinary NAG and alpha 1MG excretion remained significant even in normoalbuminuric patients. The normoalbuminuric patients with raised NAG and/or alpha 1MG excretion also had a higher prevalence of raised IV-C and laminin excretion than those with normal NAG and alpha 1MG excretion. The excretion values for IV-C and laminin, and the excretion ratios for IV-C/albumin and laminin/albumin were significantly higher in diabetic patients with evidence of incipient and clinical nephropathy than in NDRD patients, though the two patient groups had a comparable level of serum Cr and UAE. We conclude that the measurement of urinary IV-C and laminin may have potential for the evaluation of diabetic nephropathy. Furthermore, their determination might be helpful for distinguishing diabetic versus non-diabetic etiologies of altered renal function in diabetic patients.