Association of aldosterone synthase (CYP11B2) gene -344T/C polymorphism with the risk of primary chronic glomerulonephritis in the Polish population

INTRODUCTION

We evaluate whether angiotensinogen AGT M235T (rs699), angiotensin-converting enzyme ACE (I/D) (rs4646994) and aldosterone synthase CYP11B2 -344C/T (rs1799998) polymorphisms can be genetic risk factors of chronic glomerulonephritis (GN) in the Polish population.

MATERIALS AND METHODS

The study was conducted in 140 patients with primary chronic GN: mesangial proliferative GN (MesPGN) (n = 49), IgA nephropathy (IgAN) (n = 31), membranous nephropathy (MN) (n = 27), focal segmental glomerulosclerosis (FSGS) (n = 25), membranoproliferative GN (MPGN) (n = 4), and minimal change disease (MCD) (n = 4), and controls (n = 187). Genotypes were determined by HRM curve analysis for AGT M235T, by PCR and agarose gel separation for ACE (I/D), and by PCR-RFLP for CYP11B2 -344C/T.

RESULTS

We found a significant association of the CYP11B2 -344C/T polymorphism in the recessive model with all subtypes of GN (OR = 1.925 (95% CI = 1.152-3.219, p = 0.0118, p(corr) = 0.0354)). We also observed that the CYP11B2 -344C/T polymorphism in the recessive model may also be an independent significant risk factor of IgAN (OR = 2.743 (95% CI = 1.219-6.172, p = 0.0122, p(corr) = 0.0366)), FSGS (OR = 2.895 (95% CI = 1.200-6.985, p = 0.0145, p(corr) = 0.0435)), and all proliferative GNs (MesPGN, IgAN, MPGN) (OR = 2.171 (95% CI = 1.211-3.894, p = 0.0084, p(corr) = 0.0252)).

CONCLUSION

Our results suggest that the CYP11B2 -344C/T polymorphism might be an independent risk factor of IgAN, FSGS and all proliferative chronic GNs.

Urinary excretion of soluble tumour necrosis factor receptor 1 as a marker of increased risk of progressive kidney function deterioration in patients with primary chronic glomerulonephritis

BACKGROUND

The effects of tumor necrosis factor α (TNF α), a potent proinflammatory cytokine, in the kidneys are mediated by two membrane receptors (TNFR), TNFR1 and TNFR2. The expression of both TNF and TNFRs increases in several kidney diseases and is associated with the shedding of the receptors out of the cell membranes. In an experimental model of glomerulonephritis (GN), elevated concentrations of TNFRs in serum and TNFRs excretion in urine were demonstrated. The aim of this study was evaluation of urinary excretion of TNFR1 and its relationship with the clinical markers of kidney injury in patients with GN. The value of basal urinary TNFR1 excretion as a prognostic indicator of the progression of kidney function impairment was also assessed.

MATERIAL AND METHODS

Fifty-five patients with newly diagnosed, biopsy-proven primary GN were included in the study. In all patients, and in 20 healthy subjects, UTNFR1 was measured using an ELISA . In the patients, risk factors of the progression of impairment of kidney function (reduced eCcr, nephrotic syndrome, hypertension and intensity of morphological lesions in the kidneys) were evaluated. The appropriate treatment was then introduced and the patients were in follow-up for 4 years. The progression of kidney function impairment was defined as a reduction of eCcr > 5 mL/min/1.73 m2 /year during follow-up. The association of basal TNFR1 excretion with the progression was evaluated.

RESULTS

Urinary excretion of TNFR1 in the patients with GN (4039.2 ± 3801.5 pg/mgCr) was greater than in the healthy subjects (1358.9 ± 927.8 pg/mgCr, P < 0,00002). A significant negative correlation between TNFR1 excretion and eCcr (Sr=0.464, P < 0.01) and a positive correlation between TNFR1 excretion and proteinuria (Sr = 0,463, P < 0.01) were found. In 13 patients, a marked reduction of eCcr was observed during follow-up. Logistic regression analysis revealed that TNFR1 excretion > 3863.3 pg/mgCr predicts progression of renal function impairment along with advanced interstitial fibrosis in the kidney biopsy specimens at presentation.

CONCLUSION

Markedly elevated urinary TNFR1 excretion may be considered as a good marker of an activated TNFα-pathway in patients with newly diagnosed GN and as a potentially modifiable risk factor of progressive kidney function impairment.

[Childhood laterocervical abscess fistulized in the pharynx: a case study]

Cervical adenophlegmon is frequently encountered in children. We report on a case of an exceptional direct communication between a retropharyngeal abscess and a cervical adenophlegmon, observed in a 25-month-old child. Treatment comprised double antibiotic therapy and retropharyngeal drainage, which led to the subsidence of the laterocervical abscess. The progression was uncomplicated.

Efficacy and safety of low-dose chlorambucil in nephrotic patients with idiopathic membranous nephropathy

AIM

This observational study aimed to evaluate the results of treatment with low-dose chlorambucil in combination with corticosteroids in patients with idiopathic membranous nephropathy (iMGN) and nephrotic syndrome.

METHODS

Thirty-two patients with nephrotic syndrome and biopsy-proven iMGN were included in the study. At presentation, 9 patients were found to be in stage 1, 13 patients in stage 2 and 10 patients in stage 3 chronic kidney disease. In all patients, i.v. methylprednisolone pulses (500 mg/day for 3 days) were administered, followed by oral prednisone at an initial dose of 1 mg/kg per day, tapered gradually after 8 weeks to the maintenance dose of 5 mg/day after 6 months, and chlorambucil 2 mg twice daily for 6 months.

RESULTS

Complete remission of nephrotic syndrome was obtained in 14 patients (47.3%) and partial remission in 16 patients (50%). Two patients relapsed after 1 year of treatment. We did not record any severe side effects in treated patients, except glucose intolerance in 4 subjects on high corticosteroid doses.

CONCLUSION

Immunosuppressive treatment with corticosteroids and low-dose chlorambucil seems to be effective and well tolerated in nephrotic patients with iMGN.

CD52 gene polymorphism and its potential effect on the response to alemtuzumab in renal transplant recipients

CD52 is a small glycopeptide leukocyte antigen present on selected subpopulations of human cells. From the clinical point of view this protein is an important target for therapeutic interventions aimed at leukocyte depletion in hematological malignancies and post-transplant immunosuppression. Recently, two variants of CD52--rs1071849 (A119G; Asn40Ser) and rs17645 (A123G; I1e41Met)--were discovered. We now report on the distribution of these variants in kidney graft recipients and controls. Our bioinformatics findings suggest that CD52 polymorphism may affect the efficiency of GPI anchor formation and thus may indirectly alter the response to anti-CD52 agents.

Thiopurine S-methyltransferase phenotype-genotype correlation in hemodialyzed patients

Thiopurine S-methyltransferase (TPMT) is a cytosolic enzyme, catalyzing S-methylation of thiopurine drugs. TPMT exhibits autosomal codominant polymorphism. Patients carrying a variant genotype have low TPMT activity, and produce elevated levels of 6-thioguanine nucleotides (6-TGN) in their red blood cells (RBC). 6-TGN accumulation may result in azathioprine (AZA)-induced bone marrow myelosuppression in the course of treatment with the drug in a standard dosage regimen in patients following renal transplantation. In the current study, TPMT activity (phenotype) and genotype were determined in dialyzed patients, qualified for renal transplantation. TPMT activity was measured in RBC after dialysis by HPLC method. Patients were genotyped for TPMT *2, *3A and *3C variant alleles using PCR-RFLP and allele-specific PCR methods. TPMT activity ranged between 12.2 and 45.5 nmol 6-mMP/g Hb/h (median value 30.6). A significant correlation between TPMTphenotype and genotype was noted: the heterozygous patients (11.5%) demonstrated significantly lower mean TPMT activity as compared to the wild homozygotes (17 +/- 3.6 vs. 32.4 +/- 4.8 nmol 6-mMP/g Hb/h, p < 0.0003). No overlap in TPMT activity values between the group of heterozygous (range 12.2-20.6) and wild-type homozygous patients (range 22.7-45.5) was noted. TPMT activity, established after hemodialysis and TPMT genotyping results seem to be convergent in dialyzed patients, so both methods can be used for the identification of patients with lower TPMT activity. Such tests could be helpful in AZA dose individualization, and thus in reducing the risk of myelosuppression during AZA therapy following renal transplantation.

[Inherited reduced number of nephrons versus primary arterial hypertension]

The reduced number of nephrons, which was determined during fetal development may play a role as an important factor influencing blood pressure level in adult life. The results of a study which confirmed the involvement of the reduced nephron number in the etiopathogenesis of primary arterial hypertension were published recently. It was demonstrated, that the number of nephrons in the kidneys of hypertensive persons (without kidney disease) was significantly lower than in matched normotensive persons. The mean glomerular volume in hypertensive persons was markedly greater than in normotensives. The inherited reduced nephron numbers may depend not only on environmental influences acting during fetal development (like malnutrition) but also on the genetic factors. The hypothesis was presented that adaptative hypertrophy of less numerous nephrons is associated with the trait of sodium sensitivity of blood pressure. The results of the described studies may be of significant importance for clarification of the pathogenesis of primary arterial hypertension.

Arterial Hypertension due to Perirenal and Subcapsular Hematoma Induced by Renal Percutaneous Biopsy

In this study we report three patients, in whom arterial hypertension was induced by compression of the kidney parenchyma due to perirenal or subcapsular hematoma following percutaneous blind renal biopsy with use of Vim-Silverman type needle.

[Uraemic toxins and cardiovascular diseases]

The uremic syndrome is the result of the retention of solutes, which under normal conditions are excreted by the healthy kidneys into the urine. The most practical classification of uremic toxins is based on their physicochemical characteristics that influence their dialytic removal, in (a) small water soluble compounds, (b) the larger "middle molecules," and (c) the protein bound compounds. Most small water soluble compounds are not very toxic and the toxic ones often show a kinetic behavior that is different from that of urea. The incidence of vascular disease and the morbidity and mortality related to it are extremely high in the population of uremic patients. A large proportion of uremic patients suffer from inflammation. Most often, the uremic solutes that play a role in inflammation and cardio-vascular complications are middle molecules and/or protein bound. Protein bound toxins inhibit several biochemical functions. High concentrations of cytokines with an immune activating potential are present in the plasma of uremic patients.

[Outcome of immunosuppressive treatment of a patient with renal failure due to retroperitoneal fibrosis]

Retroperitoneal fibrosis (RPF) is an uncommon disease of unclear aetiology. The review of the literature over the past 20 years revealed 160 published cases. Till now, no accepted diagnostic or therapeutic strategy exist. Most of patients diseases progress to end-stage renal failure without pharmacological treatment. In the paper we report a case of a 58-year old man admitted to the department of urology due to body mass loss, lower-back pain, vomiting, development of oliguria and anuria and intermittent claudication. On physical examination arterial hypertension (180/100 mm Hg), peripheral oedema, tenderness of the enlarged kidneys and lower limbs ischemia were found. Creatinine serum level (Pcr) was 232 micromol/l (2.69 mg/dl). On ultrasonography, symmetrical hydronephrosis and the existence of a hypoechogenic mass along of the aorta and below of renal arteries was found. The diagnosis of RPF was confirmed with MRI. Ureteral catheters were inserted with subsequent decompression of both kidneys and the patient was discharged from the hospital. Seven months later he still presented symptoms of lower limbs ischemia, arterial pressure was high and Per decreased to 138 micromol/l (1.55 mg/dl). The patient was admitted to the department of internal diseases. The treatment with prednisone at the dose of 40 mg/d during 6 weeks was introduced, and the dose was decreased gradually to 10 mg/d within 6 months. Simultaneously, the patient received intravenous therapy with cyclophosphamide 600 mg/infusion once monthly during 6 months. Two month after starting immunosuppressive treatment the intermittent claudication disappeared and after six months MRI examination demonstrated the regression of RPF. The ureteral catheters were removed. After 18 months of follow up, no recurrence of RPF is observed and the kidney function is normal.

[Malnutrition -- inflammation -- atherosclerosis (MIA syndrome) in patients with renal failure]

Cardiovascular disease (CVD) is the major cause of death in end-stage renal disease (ESRD). Malnutrition may worsen patient outcome by aggravating existing inflammation and heart failure, accelerating atherosclerosis and increasing susceptibility to infection. Available data demonstrate that chronic inflammation, a non-traditional risk factor which is observed commonly in uremic patients, play a key role in the genesis of both malnutrition and CVD in ESRD. Moreover, inflammation is associated with congestive heart failure. Pro-inflammatory cytokines are pivotal to the inflammation. There is evidence that a chronic inflammation with activation of C-reactive protein, interleukin-6, tumour necrosis factor alpha and other cytokines is associated with increased oxidative stress and endothelial dysfunction in ESRD patients. Strong relations between malnutrition, inflammation and atherosclerosis in ESRD patients suggest the presence of a MIA (malnutrition, inflammation, and atherosclerosis) syndrome, which is associated with high mortality rate. Thus, it could be speculated that suppression of the vicious cycle of malnutrition, inflammation and atherosclerosis (MIA) would improve survival in ESRD patients. Therefore, the early stage of chronic renal failure is the ideal time to start therapeutic interventions.

[Arterial hypertension in glomerulonephritis]

Numerous factors causing the disturbances of pressure natriuresis mechanism may be involved in the development of arterial hypertension in kidney diseases. In particular patients with parenchymatous kidney disease, the relative effect of the impaired renal sodium excretion causing extracellular fluid volume expansion and the disequilibrium of vasoconstricting and vasorelaxating factors may differ, and in addition, these effects are influenced by the type of kidney disease, the degree of the kidney function impairment and sodium intake. In our studies on the hypertension in kidney disease we have choosen the evaluation of incidence of hypertension in the early stage of primary glomerulonephritis (GN) and the comparison of distribution of genotypes and alleles depending on insertion/deletion polymorphism of angiotensin converting enzyme (ACE) gene in patients with early stage of GN and healthy subjects. Arterial hypertension was diagnosed according to actual criteria in 46% out of 74 patients with early stage of GN. It was also found that hypertension was more common in patients with nephrotic syndrome (63%) than in patients with lower proteinuria (36% of patients). Among 50 patients with early stage of GN the distribution of genotypes and alleles depending on the polymorphism ACE gene was significantly different from 100 healthy controls. These results indicate that hypertension is often present in early stage of GN, particularly in patients with nephrotic syndrome and depends on the morphological type of glomerular disease. Further studies are needed for verification of the role of ACE gene polymorphism in the predisposition to development of GN and associated arterial hypertension.