[Estimation of the glomerular filtration rate in 2014 by tests and equations: strengths and weaknesses]

The accurate estimation of the glomerular filtration rate (GFR) is a goal of multiple interests regarding clinical, research and public health aspects. The strong relationship between progressive loss of renal function and mortality underlines the need for early diagnosis and close follow-up of renal diseases. Creatinine is the commonest biomarker of GFR in use. By reason of non-renal determinants of GFR, it is required to integrate creatinine values within equations that take in account its most important determinants (i.e., age, sex). The CKD-EPI 2009 equation is now recommended as the first line equation to estimate GFR within the general population. In this indication, it should replace MDRD that tends to overestimate the prevalence of stage 3 chronic kidney disease with GFR around 60 ml/min. However, many questions remain about the accuracy of GFR equations in specific situations such as extremes of age or body weight. The identification of new biomarkers, less determined by non-renal determinants, is of importance. Among these biomarkers, cystatin-C is more accurate to estimate GFR when it is combined to creatinine (i.e., equation CKD-EPI 2012). However the indica. tions for using cystatin-C instead of creatinine alone are still unclear and its use remains limited in routine practice. In conclusion, neither biomarker nor equation gives an accurate estimation for the whole range of GFR and for all patient populations. Limits of prediction are relying on both biomarker's properties and the range of GFR that is concerned, but also rely on the measurement methods. Therefore, it is crucial to interpret the estimated GFR according to the strengths and weaknesses of the equation in use.

Protective effects of schizandrin and schizandrin B towards cisplatin nephrotoxicity in vitro

Renal proximal tubular epithelial cells are the main targets of toxic drugs such as cisplatin (CisPt), an alkylating agent indicated for the treatment of solid organ tumors. Current techniques aiming at reducing nephrotoxicity in patients receiving CisPt are still not satisfactory as they can only partially prevent acute kidney injury. New nephroprotective strategies remain to be developed. In the present in vitro study, schizandrin (Schi) and schizandrin B (Schi B), major phytochemicals from Schisandra chinensis (Turcz.) Baill. fruits, were tested on HK-2 cells along four processes that could help alleviate CisPt toxicity. Results indicated that: (i) both Schi and Schi B enhanced cell survival via reducing apoptosis rate; (ii) only Schi showed moderate effects towards modulation of regeneration capacities of healthy cells; (iii) both Schi and Schi B limited extracellular matrix deposition; and (iv) both compounds could help preventing dedifferentiation processes via the β-catenin pathway. Schi and Schi B present promising activities for future development of protective agents against CisPt nephrotoxicity.

Complement factor H functional assay may help to monitor atypical haemolytic uraemic syndrome: a pilot study

BACKGROUND

Atypical haemolytic uraemic syndrome (aHUS) results from uncontrolled complement system activation. Complement factor H gene mutations are common causes of aHUS. Plasmatherapy, including plasma infusions and/or plasma exchanges, has been tried in this setting with various successes. At present, we lack a specific marker to monitor functional factor H deficiency-related aHUS.

METHODS

We report the use of factor H functional assay in three patients with atypical haemolytic uraemic syndrome. This assay is based on the requirement of soluble complement regulators that bind sheep red cells to prevent haemolysis. As factor H is highly abundant in the plasma, its defect results in haemolysis. Factor H activity was also measured among plasma donors.

RESULTS

One patient suffered from a plasma-dependent form of atypical haemolytic uraemic syndrome. Plasma exchanges restored higher factor H activity and were associated with a 15-months disease-free period. In the two other patients, one with a failing renal graft and the other on chronic dialysis, a bout of thrombotic microangiopathy was preceded by a drop of haemolytic activity below normal values. Plasma from healthy donors (N=65) showed only minimal variations of Factor H activity (mean activity: 98.3%, SD=4.0).

CONCLUSION

These preliminary data suggest that factor H activity could be of interest in both the diagnosis and the treatment by plasmatherapy of factor H-related aHUS.

Simultaneous measurement of protein-bound 3-chlorotyrosine and homocitrulline by LC-MS/MS after hydrolysis assisted by microwave: application to the study of myeloperoxidase activity during hemodialysis

A high degree of uremia is common in patients with end-stage renal disease and has been linked to the development of chronic inflammation and cardiovascular diseases. In conditions where transplantation is not possible, uremia can be reduced by hemodialysis although the repeated interventions have been implicated in loss of renal function, partially as a result of chronic inflammation and/or oxidative stress processes. In this context, it has been suggested that myeloperoxidase (MPO) can contribute to the oxidative stress during hemodialysis and to the cardiovascular risk. Protein damages due to MPO activity have never been assessed during hemodialysis although two of its reaction products, 3-chlorotyrosine and homocitrulline, are of interest. Indeed, the first one is a specific product of MPO activity and the formation of the second one could be catalyzed by MPO. In order to analyze these products in plasma proteins, a total hydrolysis method followed by liquid chromatography mass spectrometry analysis was developed. Different conditions of hydrolysis were tested and the optimized procedure was assessed for complete hydrolysis and artifactual chlorination. Finally, the method was used for analyzing 3-chlorotyrosine and homocitrulline in plasma proteins during a hemodialysis session in fifteen patients and data were related to measurements of MPO concentration and activity. Both increases in MPO activity and protein-bound 3-chlorotyrosine were observed, highlighting the involvement of MPO in oxidative stress during hemodialysis and further demonstrating the link between hemodialysis and cardiovascular diseases.

Review of current and "omics" methods for assessing the toxicity (genotoxicity, teratogenicity and nephrotoxicity) of herbal medicines and mushrooms

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing use of traditional herbal medicines around the world requires more scientific evidence for their putative harmlessness. To this end, a plethora of methods exist, more or less satisfying. In this post-genome era, recent reviews are however scarce, not only on the use of new "omics" methods (transcriptomics, proteomics, metabonomics) for genotoxicity, teratogenicity, and nephrotoxicity assessment, but also on conventional ones.

METHODS

The present work aims (i) to review conventional methods used to assess genotoxicity, teratogenicity and nephrotoxicity of medicinal plants and mushrooms; (ii) to report recent progress in the use of "omics" technologies in this field; (iii) to underline advantages and limitations of promising methods; and lastly (iv) to suggest ways whereby the genotoxicity, teratogenicity, and nephrotoxicity assessment of traditional herbal medicines could be more predictive.

RESULTS

Literature and safety reports show that structural alerts, in silico and classical in vitro and in vivo predictive methods are often used. The current trend to develop "omics" technologies to assess genotoxicity, teratogenicity and nephrotoxicity is promising but most often relies on methods that are still not standardized and validated.

CONCLUSION

Hence, it is critical that toxicologists in industry, regulatory agencies and academic institutions develop a consensus, based on rigorous methods, about the reliability and interpretation of endpoints. It will also be important to regulate the integration of conventional methods for toxicity assessments with new "omics" technologies.

[Acute kidney injury and drug-induced nephropathies]

All types of acute kidney injury (AKI) (functional /pre-renal, parenchymal/intra-renal, obstructive/post-renal) result in a sharp drop of the glomerular filtration rate, with variable reversibility according to the initial cause. In one case out of five, drug intake can be related to the onset of AKI. Antibiotics, analgesics and nonsteroidal anti-inflammatory drugs, angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists are the agents mostly involved, as well as iodinated radio-contrast agents. Mechanisms are often complex: toxic cellular effect directed on a nephron segment (tubular necrosis) associated or not with intraglomerular hemodynamic changes, or immune process leading to acute tubule-interstitial nephritis. Each underlying risk factor (age > 60 year, cardiac or hepatic failure, hypertension, diabetes, intra-vascular volume depletion, preexisting or unknown chronic kidney disease) must be taken into consideration by the prescribing physician because it reduces the chance of functional recovery and worsens the renal and the overall prognosis. A pre-renal additional component is often present and avoidable thanks to a strict hemodynamic monitoring. The present article summarizes some recent physiopathological aspects of AKI and makes the link between clinical situations and currently prescribed drugs. Lessons from the radio-contrast induced nephropathy are examined by taking into account prevention aspects and risk factors screening. An effective collaboration between the general practitioner and the nephrologist would benefit in optimizing the treatment of difficult cases.

Anti-HBs antibody persistence following primary vaccination with an investigational AS02(v)-adjuvanted hepatitis B vaccine in patients with renal insufficiency

BACKGROUND

Three doses of the investigational AS02(v)-adjuvanted hepatitis B virus (HBV) vaccine HB-AS02 have been shown to induce more rapid seroprotection and higher anti-HBs antibody concentrations in patients with renal insufficiency than four doses of FENDrix™ (HB-AS04), an adjuvanted HBV vaccine licensed in Europe for use in this population. This study evaluated persistence of immune response up to 36 months after primary vaccination.

METHODS

In this open, international, Phase III follow-up study, 151 pre-dialysis, peritoneal dialysis and hemodialysis patients ≥15 years of age received HB-AS02 at 0, 1, 6 months and 149 received HB-AS04 at 0, 1, 2, 6 months. Of these, 99 and 80 returned at Month 36, 76 and 62 of whom were eligible for inclusion in the Long-Term According-To-Protocol (LT-ATP) cohort for descriptive analysis of antibody persistence (mean age: 65.6 years).

RESULTS

At Month 36, 89.5% of subjects in the HB-AS02 group and 72.6% of those in the HB-AS04 group had anti-HBs antibody concentrations ≥10 mIU/ml. Anti-HBs antibody concentrations were ≥100 mIU/ml in 82.9% and 35.5% of subjects, respectively. Anti-HBs geometric mean antibody concentrations were higher in the HB-AS02 group over the 36 months of follow-up. An exploratory "time to boost" analysis confirmed that subjects who received HB-AS02 were 2.54 times more likely than those who received HB-AS04 to have anti-HBs antibody concentrations ≥10 mIU/ml at Month 36 (p=0.013 [95% CI: 1.22, 5.31]).

CONCLUSION

HB-AS02 candidate vaccine induces high and persistent anti-HBs antibody levels in pre-dialysis, peritoneal dialysis and hemodialysis patients, potentially reducing the need for booster doses in this population.

Cancer and renal insufficiency results of the BIRMA study

Background:

Half of anticancer drugs are predominantly excreted in urine. Dosage adjustment in renal insufficiency (RI) is, therefore, a crucial issue. Moreover, patients with abnormal renal function are at high risk for drug-induced nephrotoxicity. The Belgian Renal Insufficiency and Anticancer Medications (BIRMA) study investigated the prevalence of RI in cancer patients, and the profile/dosing of anticancer drugs prescribed.

Methods:

Primary end point: to estimate the prevalence of abnormal glomerular filtration rate (GFR; estimated with the abbreviated Modification of Diet in Renal Disease formula) and RI in cancer patient. Secondary end point: to describe the profile of anticancer drugs prescribed (dose reduction/nephrotoxicity). Data were collected for patients presenting at one of the seven Belgian BIRMA centres in March 2006.

Results:

A total of 1218 patients were included. The prevalence of elevated SCR (⩾1.2 mg per 100 ml) was 14.9%, but 64.0% had a GFR<90 ml min⁻¹ per 1.73 m². In all, 78.6% of treated patients (n=1087) were receiving at least one drug needing dosage adjustment and 78.1% received at least one nephrotoxic drug. In all, 56.5% of RI patients receiving chemotherapy requiring dose reduction in case of RI did not receive dose adjustment.

Conclusions:

The RI is highly frequent in cancer patients. In all, 80% of the patients receive potentially nephrotoxic drugs and/or for which dosage must be adjusted in RI. Oncologists should check the appropriate dose of chemotherapeutic drugs in relation to renal function before prescribing.

Breast cancer and renal insufficiency

Abstract #6086

Background:&#x2028; The Belgian IRMA study (Renal Insufficiency and Anticancer Medications) reported the high prevalence of renal insufficiency (RI) in 1208 cancer patients, with a glomerular filtration rate (GFR) &lt;90 ml/min for 64%. Furthermore, 78.1% were receiving potentially nephrotoxic drugs and 78.8% drugs necessitating dosage adjustment in case of renal dysfunction. We present here the results for the 510 BIRMA patients with breast cancer.&#x2028; Methods:&#x2028; Data were collected for patients presenting at one of the 7 BIRMA centers in March 2006: tumor, sex, age, weight, height, serum creatinine (SCR), bone metastasis (BM) and anticancer drugs (including dose modification). Glomerular Filtration Rate (GFR) was estimated by the aMDRD formula.&#x2028; Results:&#x2028; 510 breast cancer patients were included: mean age 58.7 years, weight 68.1 kg, height 161.6 cm, 4 men, 46.9% of patients had BM. The prevalence of elevated SCR (&gt;=1.2 mg/dL) was 7.3%, of GFR&lt;90 ml/min/1.73m² 67.8%, and of GFR&lt;60 (threshold for many anticancer drugs to consider dose modification) 15.9% (Table). 86.6% of treated patients (n=486) were receiving at least one drug needing dosage adjustment in case of renal dysfunction and 73.4% received at least one potentially nephrotoxic drug. Furthermore, the prevalence of GFR&lt;90/60 was 74.9/24.3% for breast cancer patients with BM (Table). When comparing the prevalence of GFR&lt;90 between patients with or without BM (for patients with available GFR), the frequency of RI was significantly higher for BM patients (78.9 vs 69.9%, p=0.03).&#x2028; Conclusions:&#x2028; The results of the BIRMA study showed that RI is highly frequent in breast cancer patients in Belgium and that nearly 94% of the patients receive potentially nephrotoxic drugs and/or drugs for which dosage must be adjusted in RI. Furthermore, patients with BM had a higher rate of RI than patients without. These frequencies are higher compared to data from the NHANES study in the US general population, especially for breast cancer patients with a stage 3 RI for whom SCR was normal in 55.7% of the cases. This underlines that estimating renal function with formulae such as aMDRD is mandatory in every breast cancer patient, even when SCR is within the normal range.&#x2028; &#x2028;

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6086.

Late onset of bladder urothelial carcinoma after kidney transplantation for end-stage aristolochic acid nephropathy: a case series with 15-year follow-up

BACKGROUND

Aristolochic acids are nephrotoxins and predispose to upper-tract urothelial carcinoma. The risk of bladder urothelial carcinoma after kidney transplantation and its relationship to upper-tract urothelial carcinoma is not well defined.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

Single-center cohort of 38 women given kidney transplants for end-stage aristolochic acid nephropathy.

OUTCOMES & MEASUREMENTS

The prevalence of upper urinary tract urothelial carcinoma was determined by collecting pathological results of specimens obtained by means of bilateral ureteronephrectomy. We also established the cumulative incidence of bladder urothelial carcinoma in biopsies performed during prospective screening cystoscopies during a 15-year follow-up.

RESULTS

Upper-tract urothelial carcinoma was found in 17 patients with aristolochic acid nephropathy (44.7%). During follow-up, bladder urothelial carcinoma was diagnosed in 15 patients 68 to 169 months after cessation of aristolochic acid exposure (39.5%): 8 urothelial carcinoma in situ, 4 noninvasive low-grade papillary urothelial carcinoma, and 3 infiltrating urothelial carcinoma. 12 of 17 patients (71%) with a history of upper-tract urothelial carcinoma developed bladder urothelial carcinoma during follow-up, whereas this occurred in only 3 of 21 patients (14%) without upper-tract urothelial carcinoma (P < 0.01). Despite local and/or systemic chemotherapy, 3 patients died and 2 radical cystectomies were performed.

LIMITATIONS

Small sample size of this case series.

CONCLUSIONS

Upper-tract and bladder urothelial carcinoma are dramatic complications in kidney transplant recipients with aristolochic acid nephropathy, confirming the carcinogenic properties of aristolochic acids. We identified upper-tract urothelial carcinoma as a potent risk factor for the subsequent development of bladder urothelial carcinoma after kidney transplantation for aristolochic acid nephropathy. Because this complication may occur years after aristolochic acid discontinuation, we suggest regular cystoscopies in addition to the bilateral ureteronephrectomy in kidney transplant recipients with aristolochic acid nephropathy.