Urine alpha1-microglobulin is a better marker for early tubular dysfunction than beta2-microglobulin among tenofovir-exposed human immunodeficiency virus-infected men who have sex with men

Characteristics and predictors of low-grade renal artery stenosis in female patients with CKD

AIM

Renal artery stenosis (RAS) is an important cause of chronic kidney disease (CKD). The main purpose of this study was to explore the clinical characteristics and predictors of low-grade RAS in female patients with CKD.

METHODS

One hundred and five female CKD patients from Huadong Hospital affiliated with Fudan University who underwent 3 T non-contrast renal artery magnetic resonance angiography (MRA) were analyzed. Basic statistics methods were used in the study, such as independent-sample t test,non-parametric test, binary logistic regression analysis and ROC analysis.

RESULTS

In this cross-sectional study, there were 50 patients with RAS and 55 without RAS (47.6% versus 52.4%). Binary logistic regression analysis demonstrated that low-level ALB and lymphocyte count, high-level SP, BUN and NLR were independent risk factors for low-grade RAS in female patients with CKD. ROC analysis indicated that eGFR, FeNa and UBCR, ALB, lymphocyte count and NLR had the best predictive value for low-grade RAS, especially eGFR with a sensitivity of 65.50% and specificity of 72.00% and FeNa with a sensitivity of 71.10% and specificity of 72.20% and BUCR with a sensitivity of 71.10% and specificity of 68.10%.

CONCLUSION

In female patients with CKD, FeNa, eGFR, ALB, UBCR, lymphocyte count and NLR may be good predictors of low-grade RAS, especially eGFR, FeNa and BUCR.

Evaluation of hydroxylated metabolites of polycyclic aromatic hydrocarbons and biomarkers of early kidney damage in indigenous children from Ticul, Yucatán, Mexico

Polycyclic aromatic hydrocarbons (PAHs) are environmental persistent chemicals, produced by the incomplete combustion of solid fuels, found in smoke. PAHs are considered carcinogenic, teratogenic, and genotoxic. Children are susceptible to environmental pollutants, particularly those living in high-exposure settings. Therefore, the main objective of this study was to evaluate the exposure to PAHs through hydroxylated metabolites of PAHs (OH-PAHs), 1-hydroxynaphtalene (1-OH-NAP), and 2-hydroxynaphtalene (2-OH-NAP); 2-,3-, and 9-hydroxyfluorene (2-OH-FLU, 3-OH-FLU, 9-OH-FLU); 1-,2-,3-, and 4-hydroxyphenanthrene (1-OH-PHE, 2-OH-PHE, 3-OH-PHE, 4-OH-PHE); and 1-hydroxypyrene (1-OH-PYR), as well as kidney health through biomarkers of early kidney damage (osteopontin (OPN), neutrophil gelatinase-associated lipocalin (NGAL), α1-microglobulin (α1-MG), and cystatin C (Cys-C)) in children from an indigenous community dedicated to footwear manufacturing and pottery in Ticul, Yucatán, Mexico. The results show a high exposure to PAHs from the found concentrations of OH-PAHs in urine in 80.5% of the children in median concentrations of 18.4 (5.1-71.0) μg/L of total OH-PAHs, as well as concentrations of kidney damage proteins in 100% of the study population in concentrations of 4.8 (3-12.2) and 7.9 (6.5-13.7) μg/g creatinine of NGAL and Cys-C respectively, and 97.5% of the population with concentrations of OPN and α1-MG at mean concentrations of 207.3 (119.8-399.8) and 92.2 (68.5-165.5) μg/g creatinine. The information provided should be considered and addressed by the health authorities to establish continuous biomonitoring and programs to reduce para-occupational exposure in the vulnerable population, particularly children, based on their fundamental human right to health.

HCV cirrhotic patients treated with direct-acting antivirals: Detection of tubular dysfunction and resolution after viral clearance

BACKGROUND/AIMS

Hepatitis C virus (HCV) has been identified in tubular epithelial cells of infected patients; however, the presence of tubular dysfunction, which is a risk factor for chronic kidney disease (CKD), has never been examined in vivo. The present prospective longitudinal study aimed to estimate the prevalence of tubular dysfunction alone or with glomerular damage and its evolution after HCV clearance in cirrhotic patients.

METHODS

One hundred and thirty-five consecutive Child-Pugh A cirrhotic patients were evaluated before antiviral treatment and 6 months after the end of therapy. Tubular dysfunction was evaluated by urinary alpha1-microglobulin to creatinine ratio (α1-MCR), and glomerular damage was assessed by urinary albumin to creatinine ratio (ACR).

RESULTS

Almost all the patients (93.3%) showed a normal or mildly decreased e-GFR (KDIGO-G1/G2-categories). Tubular dysfunction was found in 23.7% (32/135) of patients, co-occurring with glomerular damage in 37.5% (12/32) of cases, while glomerular damage was found in 16.3% (22/135) of patients. In multiple logistic regression, glomerular damage and the concomitant presence of diabetes and hypertension were the only predictors significantly associated with tubular dysfunction. After HCV clearance, patients experienced a significant reduction of α1-MCR levels (21.0 vs 10.5 μg/mg, P = .009) and tubular dysfunction resolved in 57.1% of subjects.

CONCLUSIONS

Tubular dysfunction is an unrecognized feature of HCV-related kidney disease in cirrhotic patients and its presence should be primarily investigated in subjects with glomerular damage, diabetes and hypertension, despite normal e-GFR. Tubular dysfunction resolves in the majority of cases after HCV clearance; however, it may persist after antiviral treatment and further studies should evaluate its long-term impact on kidney function.

Therapy with 2'-O-Me Phosphorothioate Antisense Oligonucleotides Causes Reversible Proteinuria by Inhibiting Renal Protein Reabsorption

Antisense oligonucleotide therapy has been reported to be associated with renal injury. Here, the mechanism of reversible proteinuria was investigated by combining clinical, pre-clinical, and in vitro data. Urine samples were obtained from Duchenne muscular dystrophy (DMD) patients treated with drisapersen, a modified 2′O-methyl phosphorothioate antisense oligonucleotide (6 mg/kg). Urine and kidney tissue samples were collected from cynomolgus monkeys (Macaca fascicularis) dosed with drisapersen (39 weeks). Cell viability and protein uptake were evaluated in vitro using human conditionally immortalized proximal tubule epithelial cells (ciPTECs). Oligonucleotide treatment in DMD patients was associated with an increase in urinary alpha-1-microglobulin (A1M), which returned to baseline following treatment interruptions. In monkeys, increased urinary A1M correlated with dose-dependent accumulation of oligonucleotide in kidney tissue without evidence of tubular damage. Furthermore, oligonucleotides accumulated in the lysosomes of ciPTECs and reduced the absorption of A1M, albumin, and receptor-associated protein, but did not affect cell viability when incubated for up to 7 days. In conclusion, phosphorothioate oligonucleotides appear to directly compete for receptor-mediated endocytosis in proximal tubules. We postulate that oligonucleotide-induced low molecular weight proteinuria in patients is therefore a transient functional change and not indicative of tubular damage.

Evaluation of Benzene Exposure and Early Biomarkers of Kidney Damage in Children Exposed to Solvents Due to Precarious Work in Ticul, Yucatán, México

Background:

The child labor situation has been associated with precarious job conditions and poor health conditions because children are often exposed to unsafe work environments, stressful psycho-social work conditions, scarce or no access to protective services, and heavy work burdens.

Objective:

The aim of the study was to evaluate markers of exposure to benzene through the exposure biomarker trans, trans-muconic acid (tt-MA), and biomarkers of early renal damage in children who work in sites that are under precarious job conditions.

Method:

Samples of urine were obtained from children (aged 6–12 years old) who resided in Ticul, Yucatan, Mexico. Exposure to benzene was assessed through trans, trans-muconic acid (t,t-MA). Evaluated renal damage biomarkers were: Cystatin-C (Cys-C), Osteopontin (OPN), α1-Microglobulin (α1-MG) and Neutrophil Gelatinase-Associated Lipocalin (NGAL).

Findings:

Children who live where the workplace is inside the dwelling presented higher mean levels of tt-MA (0.59 mg/g creatinine) compared with those who live away from the workshops (0.19 mg/g creatinine). Likewise, mean levels of NGAL (4.7, 5.2 ng/ml), albuminuria (10, 10 ng/ml), Cys-C (11.8, 7.5 ng/ml), OPN (224.4, 226.5 ng/ml) and α1-MG (96.6, 73.6 ng/ml) were found in children where the workplace was inside the dwelling and outside, respectively.

Conclusion:

Our data indicate that the children who work under precarious job conditions are exposed to benzene, and they exhibit protein levels that suggest renal damage in a population in precarious working conditions. Therefore, the child population should be considered as the most vulnerable and susceptible to suffer adverse health effects.

Prevalence of Nephrotoxicity in HIV Patients Treated with Tenofovir Disoproxil Fumarate: A Single-center Observational Study

Objectives

Tenofovir disoproxil fumarate (TDF) has been reported to cause nephrotoxicity necessitating cessation in some patients. No information is available on the nephrotoxic effect of TDF in Omani or regional patients with HIV infection. We sought to determine the prevalence of the nephrotoxic effects of TDF in our cohort of Omani patients with HIV and investigate the nephrotoxic effects of other cofactors.

Methods

We conducted an observational cohort study on 83 Omani patients currently on TDF-containing antiretroviral therapy. Renal dysfunction was monitored by measuring the serum creatinine estimated glomerular function rate (eGFR), urinary protein creatinine ratio (uPCR), and fractional excretion of phosphate (FEPi). Fisher's exact test was used to determine any additional nephrotoxic effects of cofactors.

Results

The median values for the duration of TDF use, patient age, and body mass index (BMI) at the time of the study were 178 weeks (range = 3-554), 42 years (range = 21-80), and 27 (range = 17.4-42.7), respectively. The median initial CD4 count and viral load were 205 × 10⁶/L (range = 3-1745) and 37 250 copies/mL (range = undetectable-9 523 428), respectively. FEPi was high in two (2.4%) patients, moderate in 26 (31.3%), and low in 55 (66.3%) patients. uPCR was high in 10 (12.0%) patients, moderate in 28 (33.7%), and low in 45 (54.2%) patients. No cofactors added to the nephrotoxicity except hypertension (p = 0.045).

Conclusions

Better definitions for TDF-associated toxicity are needed. uPCR is not a very good indicator of TDF-associated tubular dysfunction. Omani patients with HIV on TDF have a 4% prevalence of renal toxicity, but a study with a larger number of patients is required to explore this observation further. Cofactors like duration of TDF use, age, BMI, gender, diabetes mellitus, and use of protease inhibitors did not have an impact on the severity of FEPi and uPCR.

α1-Microglobulin Protects Against Bleeding-Induced Oxidative Damage in Knee Arthropathies

Knee injury increases the risk of developing knee osteoarthritis (OA). Recent evidence suggests involvement of oxidative stress induced by inflammation and bleeding in the joint. This study investigates the role in this process of α₁-microglobulin (A1M), a plasma and tissue antioxidant protein with reducing function, and heme- and radical-binding properties. We studied matched knee synovial fluid (sf) and serum (s) samples from 122 subjects (mean age 40 years, 31% females): 10 were knee healthy references, 13 had acute inflammatory arthritis (AIA), 79 knee injury 0–10 years prior to sampling, and 20 knee OA. Using immunoassays, we measured sf-A1M and s-A1M, sf-hemoglobin (sf-Hb), sf-total free heme (sf-Heme), and sf-carbonyl groups (sf-Carbonyl). We explored associations by partial correlation, or linear regression models with adjustments for age, sex and diagnosis, and evaluated diagnostic capacity by area under the receiver operator characteristics curve (AUC). The AIA group had 1.2- to 1.7-fold higher sf-A1M and s-A1M concentrations compared to the other diagnostic groups; other biomarkers showed no between-group differences. sf-A1M and s-A1M were with AUC of 0.76 and 0.78, respectively, diagnostic for AIA. In the injury group, the amount of bleeding in the joint was inversely correlated to time after injury when measured as sf-Heme (r = -0.41, p < 0.001), but not when measured as sf-Hb (r = -0.19, p = 0.098). A similar inverse association with time after injury was noted for sf-A1M (r = -0.30, p = 0.007), but not for s-A1M and sf-Carbonyl. Linear regression models showed that sf-Heme was more strongly associated with sf-A1M and sf-Carbonyl than sf-Hb. Independent of diagnosis, sf-Heme explained 5.7% of the variability in sf-A1M and 3.0% in the variability in sf-Carbonyl, but appeared unrelated to s-A1M. High sf-A1M and low sf-Heme or sf-Hb were independently associated with low sf-Carbonyl. In conclusion, our results demonstrate that independent of disease, Hb and heme within a knee joint correlates with an increased sf-A1M concentration that appears to be protective of oxidative damage, i.e., a reduction in carbonyl groups. High concentrations of A1M in synovial fluid and serum was further diagnostic for AIA.

A study on the biological reference interval of urinary alpha 1-microglobulin in a group of Chinese people

OBJECTIVE

The aim of this study was to explore the possible influences of age and gender on urinary Alpha 1-Microglobulin (α1-MG) concentrations and establish specific reference values of urinary α1-MG in a group of healthy adults.

METHODS

Two hundred and ninety-nine adults (141 males and 158 females) aged 20-60 were selected and grouped by gender and age. Urinary levels of α1-MG were detected in morning spot-urine samples, and statistical analysis was performed to explore the association between urinary α1-MG and clinical parameters, and the differences between groups were compared. The 95th percentile of distribution was used as the normal upper limit.

RESULTS

The value of urinary α1-MG was sex-dependent (P<0.001), the 95th percentile of urinary α1-MG of males was 26.4 mg/L, whereas females was 8.6 mg/L. Whereas urinary α1-microglobulin-to-creatinine ratio (α1-MG/Cr) was both gender-and age-dependent (both P<0.001), and age 30 may be the cut-off point in this study. The 95th percentile of males and females aged 20-30 was 16.9 mg/g, of males aged 31-60 was 19.8 mg/g, of females aged 31-60 was 28.5 mg/g.

DISCUSSIONS

The relationship between urinary α1-MG concentrations and gender, age is different from previous studies. It is recommended that hospitals and laboratories should develop their own α1-MG reference intervals based on their experimental conditions.

Association Between Urinary Alpha1-Microglobulin Levels and Nonalcoholic Fatty Liver Disease: A Cross-Sectional Study

BACKGROUND

We aimed to explore the association between urinary alpha1-microglobulin (A1M) levels and nonalcoholic fatty liver disease (NAFLD) in a Chinese population.

STUDY

We performed a cross-sectional study among 2,215 Chinese who attended their annual health examination at First Affiliated Hospital, College of Medicine, Zhejiang University. Urinary A1M-creatinine ratio and other clinical and laboratory parameters were measured.

RESULTS

A total of 20.9% of subjects fulfilled the diagnostic criteria of NAFLD. NAFLD subjects had significantly higher urinary A1M-creatinine ratios. These levels were positively associated with NAFLD prevalence. The association between A1M-creatinine ratio and NAFLD was independent of hyperglycemia status. Stepwise regression showed that urinary A1M-creatinine ratio was significantly associated with the risk for NAFLD. Urinary A1M-creatinine ratio was an independent factor predicting advanced fibrosis (FIB-4 ≥1.3) in NAFLD patients.

CONCLUSIONS

Our results showed a significant association between urinary A1M-creatinine ratio and NAFLD.

Unique proximal tubular cell injury and the development of acute kidney injury in adult patients with minimal change nephrotic syndrome

Background

Adult patients with minimal change nephrotic syndrome (MCNS) are often associated with acute kidney injury (AKI). To assess the mechanisms of AKI, we examined whether tubular cell injuries unique to MCNS patients exist.

Methods

We performed a retrospective analysis of clinical data and tubular cell changes using the immunohistochemical expression of vimentin as a marker of tubular injury and dedifferentiation at kidney biopsy in 37 adult MCNS patients. AKI was defined by the criteria of the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guidelines for AKI.

Results

Thirteen patients (35.1%) were designated with AKI at kidney biopsy. No significant differences in age, history of hypertension, chronic kidney disease, diuretics use, proteinuria, and serum albumin were noted between the AKI and non-AKI groups. Urinary N-acetyl-β-D-glucosaminidase (uNAG) and urinary alpha1-microglobulin (uA1MG) as markers of tubular injury were increased in both groups, but the levels were significantly increased in the AKI group compared with the non-AKI group. The incidence of vimentin-positive tubules was comparable between AKI (84.6%) and non-AKI (58.3%) groups, but vimentin-positive tubular area per interstitial area was significantly increased in the AKI group (19.8%) compared with the non-AKI group (6.8%) (p = 0.011). Vimentin-positive injured tubules with tubular simplification (loss of brush-border of the proximal tubule/dilated tubule with flattening of tubular epithelium) were observed in the vicinity of glomeruli in both groups, suggesting that the proximal convoluted tubules were specifically injured. Two patients exhibited relatively severe tubular injuries with vimentin positivity and required dialysis within 2 weeks after kidney biopsy. The percentage of the vimentin-positive tubular area was positively correlated with uNAG but not with uA1MG in the non-AKI group.

Conclusions

Proximal tubular injuries with increased uNAG exist in MCNS patients without renal dysfunction and were more severe in the AKI group than they were in the non-AKI group. The unique tubular injuries probably due to massive proteinuria might be a predisposing factor for the development of severe AKI in adult MCNS patients.

Low cadmium exposure in males and lactating females-estimation of biomarkers

BACKGROUND

Urine cadmium (Cd) and renal function biomarkers, mostly analysed in urine spot samples, are well established biomarkers of occupational exposure. Their use and associations at low environmental level are common, but have recently been questioned, particularly in terms of physiological variability and normalisation bias in the case of urine spot samples.

AIM

To determine the appropriateness of spot urine and/or blood Cd exposure biomarkers and their relationships with renal function biomarkers at low levels of exposure. To this end, we used data from Slovenian human biomonitoring program involving 1081 Slovenians (548 males, mean age 31 years; 533 lactating females, mean age 29 years; 2007-2015) who have not been exposed to Cd occupationally.

RESULTS

Geometric means (GMs) of Cd in blood and spot urine samples were 0.27ng/mL (0.28 for males and 0.33 for females) and 0.19ng/mL (0.21 for males and 0.17 for females), respectively. Differing results were obtained when contrasting normalisation by urine creatinine with specific gravity. GMs of urine albumin (Alb), alpha-1-microglobulin (A1M), N-acetyl-beta-glucosaminidase (NAG), and immunoglobulin G (IgG) were far below their upper reference limits. Statistical analysis of unnormalised or normalised urine data often yielded inconsistent and conflicting results (or trends), so association analyses with unnormalised data were taken as more valid. Relatively weak positive associations were observed between urine Cd (ng/mL) and blood Cd (β=0.11, p=0.002 for males and β=0.33, p<0.001 for females) and for females between urine NAG and blood Cd (β=0.14, p=0.04). No associations were found between other renal function biomarkers and blood Cd. Associations between Cd and renal function biomarkers in urine were stronger (p<0.05, β=0.11-0.63). Mostly, all of the associations stayed significant but weakened after normalisation for diuresis. In the case of A1M, its associations with Cd were influenced by current smoking and blood Pb in males and by pre-pregnancy smoking and blood Se in females (β up to 0.34, p<0.001). Statistical analysis of unnormalised or normalised urine data often yielded inconsistent and conflicting results (or trends), so association analyses data with unnormalised were taken as more valid.

CONCLUSIONS

The observed uncertainties introduced by urine normalisation, particularly by creatinine, confirm blood Cd as a superior low-Cd exposure biomarker versus urine Cd in cases when 24h urine is unattainable. Evidence that A1M can be positively related to Cd, smoking (current or pre-pregnancy), Pb, and Se status, points to the versatile biological functions of A1M.

Urinary Markers of Tubular Injury in HIV-Infected Patients

Renal disease is a common complication of HIV-infected patients, associated with increased risk of cardiovascular events, progression to AIDS, AIDS-defining illness, and mortality. Early and accurate identification of renal disease is therefore crucial to improve patient outcomes. The use of serum creatinine, along with proteinuria, to detect renal involvement is essentially to screen for markers of glomerular disease and may not be effective in detecting earlier stages of renal injury. Therefore, more sensitive and specific markers are needed in order to early identify HIV-infected patients at risk of renal disease. This review article summarizes some new and important urinary markers of tubular injury in HIV-infected patients and their clinical usefulness in the renal safety follow-up of TDF-treated patients.

Effects of Sugammadex and Neostigmine on Renal Biomarkers

Background

Neostigmine, the currently commonly used agent for reversal of neuromuscular blockade. Sugammadex is a novel and unique compound designed as an antagonist of steroidal neuromuscular blockers. In this study, we evaluated the effects of sugammadex or neostigmine on kidney functions in patients scheduled for elective surgery.

Material/Methods

Patients scheduled for a surgical procedure under desflurane/opioid anesthesia received an intubating dose rocuronium. Patients were divided into 2 groups receiving either sugammadex or neostigmine atropine to reverse neuromuscular blockade. Cystatin C, creatinine, urea, blood urea nitrogen, sodium, potassium, and calcium levels in the blood and α₁microglobulin, β₂microglobulin, and microalbumin levels in the urine were measured.

Results

There was no significant difference between the groups with regard to the demographic data. In the Neostigmine Group, although β₂microglobulin and microalbumin were similar, a significant increase was found in the postoperative α₁microglobulin and cystatin C values. In the Sugammadex Group, although β₂-microglobulin and cystatin C were similar, a significant increase was found in the postoperative α₁-microglobulin and microalbumin values. The only significant difference was cystatin C value variation in the Neostigmine Group compared to the Sugammadex Group.

Conclusions

We believe that the use of more specific and sensitive new-generation markers like cystatin C to evaluate kidney function will provide a better understanding and interpretation of our results. Sugammadex has more tolerable effects on kidney function in patients than does neostigmine. However, when compared to preoperative values, there is a negative alteration of postoperative values. Neostigmine and sugammadex do not cause renal failure but they may affect kidney function.