Increased blood pressure in adult offspring of families with Balkan endemic nephropathy: a prospective study

Genetic loci that affect aristolochic acid-induced nephrotoxicity in the mouse

Aristolochic acids (AA) are plant-derived nephrotoxins and carcinogens found in traditional medicines and herbal remedies. AA causes aristolochic acid nephropathy (AAN) and is a suspected environmental agent in Balkan endemic nephropathy (BEN) and its associated upper urothelial cancer. Approximately 5-10% of individuals exposed to AA develop renal insufficiency and/or cancer; thus a genetic predisposition to AA sensitivity has been proposed. The mouse is an established animal model of AAN, and inbred murine strains vary in AA sensitivity, confirming the genetic predisposition. We mapped quantitative trait loci (QTL) correlated with proximal tubule dysfunction after exposure to AA in an F2 population of mice, derived from breeding an AA-resistant strain (C57BL/6J) and an AA-sensitive strain (DBA/2J). A single main QTL was identified on chromosome 4 (Aanq1); three other interacting QTLs, (Aanq2-4) also were detected. The Aanq1 region was also detected in untreated mice, raising the possibility that preexisting differences in proximal tubule function may affect the severity of AA-elicited toxicity. This study lays the groundwork for identifying the genetic pathways contributing to AA sensitivity in the mouse and will further our understanding of human susceptibility to AA found widely in traditional medicines.

Reduced kidney size in adult offspring of Balkan endemic nephropathy patients and controls: a prospective study

INTRODUCTION

Reduced kidney size has been proposed as a criterion for clinical diagnosis of Balkan endemic nephropathy (BEN). Some studies suggest that smaller kidneys are found in advanced stages of BEN, whereas others reported them in earlier stages. To investigate the clinical course of kidney sizes in the offspring of BEN and non-BEN parents, we followed up a cohort of adult offspring over 5 years. We hypothesized that parental history affects kidney dimensions.

METHODS

Four repeated ultrasound measurements of kidney length and cortex width were conducted in 121 offspring of BEN and 98 offspring of non-BEN parents. Repeated measurements were analyzed using mixed models adjusting for gender and time-dependent information on other kidney diseases, diabetes, age, height and year of follow-up.

RESULTS

A reduction of kidney length was associated with maternal BEN (-4 mm, P = 0.001). We detected a parallel decline in kidney length in the various offspring groups. However, kidney cortex width was significantly smaller when both parents or the mother had BEN and offspring age > or =60 years (-1.88 mm, P = 0.0003; -1.03 mm, P = 0.05). In the 5th year of follow-up, 37 participants developed BEN (14 confirmed, 23 suspected). Kidney cortex width at baseline was smaller in offspring who developed BEN (P = 0.0001).

CONCLUSIONS

The development of kidney dimensions depends on the parental BEN status and offspring age. In BEN offspring, ultrasound measurements of the kidney cortex width seem to have a prognostic value.

Early detection of Balkan endemic nephropathy in Bosanska Posavina

Balkan endemic nephropathy (BEN) is a chronic tubulointersticial nephropathy that is diagnosed in a few agrarian regions of Balkan. Even tough numerous dilemmas and conflicting opinions regarding BEN etiology are encountered in literature, prevailing theory is that BEN is caused by chronic poisoning with aristolochic acid ingested by food in people with genetic predisposition to this disease. BEN is categorized as a toxic tubulointerstitial nephropathy, with clinical picture and disease progression not differing from other tubulointerstitial nephropathies, but with insidious and gradual progression to end stage renal disease. There is no specific and sensitive diagnostic biomarkers for BEN and we use epidemiological and functional diagnostic criteria. It is considered that BEN affects up to 10% of population in endemic region. According to Renal Register of Bosnia and Herzegovina, there are around 15% of BEN patients on chronic dialysis program, but no official data on the number of predialysis BEN patients, because of lack of adequate demographic data and screening or systematic examinations of the population living in the affected region since 1991. The members of the Society of nephrology, dialysis and transplantation of Bosnia and Herzegovina organized screening in two villages of Bosanska Posavina, as a part of the "Program Program of detection of chronic kidney diseases in high-risk population in Bosnia and Herzegovina", project which was approved from International Society of nephrology. In this paper we analyze preliminary results of that Program and discuss previous studies about BEN in Bosnia and Herzegovina, particularly diagnostic criteria and biomarkers of BEN.

The relation of C--reactive protein to chronic kidney disease in African Americans: the Jackson Heart Study

Background

African Americans have an increased incidence and worse prognosis with chronic kidney disease (CKD - estimated glomerular filtration rate [eGFR] <60 ml/min/1.73 m²) than their counterparts of European-descent. Inflammation has been related to renal disease in non-Hispanic whites, but there are limited data on the role of inflammation in renal dysfunction in African Americans in the community.

Methods

We examined the cross-sectional relation of log transformed C-reactive protein (CRP) to renal function (eGFR by Modification of Diet and Renal Disease equation) in African American participants of the community-based Jackson Heart Study's first examination (2000 to 2004). We conducted multivariable linear regression relating CRP to eGFR adjusting for age, sex, body mass index, systolic and diastolic blood pressure, diabetes, total/HDL cholesterol, triglycerides, smoking, antihypertensive therapy, lipid lowering therapy, hormone replacement therapy, and prevalent cardiovascular disease events. In a secondary analysis we assessed the association of CRP with albuminuria (defined as albumin-to-creatinine ratio > 30 mg/g).

Results

Participants (n = 4320, 63.2% women) had a mean age ± SD of 54.0 ± 12.8 years. The prevalence of CKD was 5.2% (n = 228 cases). In multivariable regression, CRP concentrations were higher in those with CKD compared to those without CKD (mean CRP 3.2 ± 1.1 mg/L vs. 2.4 ± 1.0 mg/L, respectively p < 0.0001). CRP was significantly associated with albuminuria in sex and age adjusted model however not in the multivariable adjusted model (p > 0.05).

Conclusion

CRP was associated with CKD however not albuminuria in multivariable-adjusted analyses. The study of inflammation in the progression of renal disease in African Americans merits further investigation.

Offspring of parents with Balkan Endemic Nephropathy have higher C-reactive protein levels suggestive of inflammatory processes: a longitudinal study

Background

Despite the characteristic extensive tubulointerstitial fibrosis, Balkan Endemic Nephropathy (BEN) is usually considered a non-inflammatory disease.

Methods

We examined a marker of inflammation, C-reactive protein (CRP), in the offspring of patients with BEN, a population at risk for BEN, prior to development of established disease to determine if an inflammatory process could be identified in the early stages of the disease. In 2003/04, 102 adult offspring whose parents had BEN and a control group of 99 adult offspring of non-BEN patients were enrolled in this prospective study. This cohort was re-examined yearly for four consecutive years. Levels of serum CRP were measured in years 3 and 4 and compared between groups. The data were analyzed with mixed models.

Results

Compared to controls, offspring of BEN parents had statistically higher CRP levels in two consecutive years, suggestive of early inflammatory reactivity. Whenever the mother was affected by BEN (both parents, or mother only), serum CRP was significantly increased, but not if only the father had BEN. CRP was inversely related to kidney cortex width but not to markers or renal function.

Conclusion

Early stages of BEN may involve inflammatory processes. The observation of a maternal involvement supports the concept of fetal programming, which has been implicated in the pathogenesis of other chronic kidney diseases.

Prevalence of Balkan endemic nephropathy has not changed since 1971 in the Kolubara region in Serbia

BACKGROUND/AIMS

Thirty-one years after the first cross-sectional study, the population of Vreoci, a Balkan endemic nephropathy (BEN) village, was reinvestigated in order to determine the current prevalence of BEN and the clinical and laboratory characteristics of BEN family members with detected signs of kidney disease.

METHODS

A total of 2,009 inhabitants (82% of the adult population) of the village were examined. Danilovic's criteria were used for diagnosis and classification of BEN.

RESULTS

The prevalence of BEN (1.70%) was similar to that in 1971 (1.67%). Diagnosis of BEN was established in 19 BEN family members, suspected BEN in 23, proteinuria in 29, while 16 healthy members were examined as controls. Urine protein, alpha1-microglobulin levels and frequency of glucosuria were significantly higher and kidney length significantly smaller in the three patient groups than in healthy persons. Serum urea and creatinine levels were significantly higher, but creatinine clearance was lower in BEN and BEN suspected patients than in the other two groups.

CONCLUSION

The prevalence of BEN remains stable over time in Vreoci village. Manifested disease was found in both BEN and BEN suspected patients. In persons with proteinuria but not enough criteria for BEN, tubular disorders and hypertension were frequently found.