Adherence to the Mediterranean Diet Improves Fatty Acids Profile in Pediatric Patients with Idiopathic Nephrotic Syndrome

The fatty acid profiles of patients with idiopathic nephrotic syndrome (INS) are different from that of healthy controls, even during remission, revealing an increase of the pro-inflammatory omega 6 series. It is still unknown whether the concomitance of nephrotic syndrome affects the potential positive effects of the Mediterranean diet on the levels of omega 3 and 6 fatty acids. We performed a cross-sectional study to evaluate the association between the adherence to the Mediterranean diet and fatty acid profile in 54 children with INS. The dietary habits were assessed through the validated Kidmed questionnaire. Patients with higher adherence had lower levels of linoleic acid and total omega-6. Moreover, a negative correlation between proteinuria and the anti-inflammatory omega-3 series was found. In conclusion, patients with INS with proteinuria and low adherence to the Mediterranean diet have an imbalance in the omega-6/omega-3 ratio that may benefit from following the Mediterranean diet.

Immunodeficiency and inborn disorders of vitamin B12 and folate metabolism

PURPOSE OF REVIEW

Immune dysfunction, including severe combined immunodeficiency, has been described in genetic disorders affecting the metabolism of the vitamins cobalamin (vitamin B12) and folate. We have reviewed reports of clinical findings in patients with a number of inborn errors of cobalamin or folate metabolism, specifically looking for immune problems.

RECENT FINDINGS

There is little evidence that immune function is affected in most of the disorders. Exceptions are Imerslund-Gräsbeck syndrome and hereditary folate malabsorption (affecting intestinal absorption of cobalamin and folate, respectively), transcobalamin deficiency (affecting transport of cobalamin in blood and cellular cobalamin uptake), and methylenetetrahydrofolate dehydrogenase 1 deficiency (catalyzing cytoplasmic interconversion of reduced folate coenzyme derivatives).

SUMMARY

Although some inborn errors of cobalamin or folate can be associated with immune dysfunction, the degree and type of immune dysfunction vary with no obvious pattern.

[IMERSLUND-GRÄSBECK SYNDROME CONGENITAL FORM OF VITAMIN B12 DEFICIENCY ANEMIA]

Normal red blood cells maturation depends on many different hematological factors, including vitamin (vit.) B12. Megaloblastic anemias are basically caused by vit. B12 deficiency. In childhood the deficiency of this vitamin is extremely rare. The article captures findings of observation of the patient with rare form congenital vit. B12 deficiency anemia - Imerslund-Gräsbeck syndrome. The disease is characterized with selective intestinal malabsorption of vit. B12 and permanent proteinuria, without sings of kidney disease. The diagnosis was confirmed by our team in early childhood and based on the history, clinical and paraclinical data. After two weeks of specific treatment with vit. B12 , complete clinical - hematological remission was achieved. Treatment includes lifelong vit. B12 injections once per month. Cathamnesic observation for 18 months revealed that the patient is in remission, but there was continued macrocytosis of red blood cells and mild proteinuria. The presented case is interesting as a rare case of megaloblastic anemia caused by vit. B12 deficiency in childhood. Such patients often treated under different diagnosis. In such cases early diagnosis, treatment and prevention are crucial for the good prognosis.

[Congenital nephrotic syndrome of the Finnish type--key to the mechanisms of proteinuria]

Congenital nephrotic syndrome of the Finnish type is a serious renal disease belonging to the Finnish disease heritage. It appears as substantial proteinuria, hypoproteinemia and edema in a newborn. Kidney transplantation is the only effective treatment. The cause of the disease is a mutation in the gene encoding the nephrin protein. Nephrin is produced by the epithelial cell (podocyte) of the glomerulus. It is expressed in the slit membrane connecting the pedicles of the podocyte. This finding has revolutionized the concept of glomerular filtration and set off active research on the pathogenetic mechanisms of proteinuria.

Two cases of congenital nephrotic syndrome

The clinical course and renal histological changes in two patients with congenital nephrotic syndrome are presented. Both patients developed edema and proteinuria at 2 days of age. Steroids and immunosuppressive drugs were not used in either patient. One patient showed gradual disappearance of nephrotic syndrome and proteinuria during the 16-month follow-up. In the other patient, the nephrotic state persisted and nephrotic complications necessitated bilateral nephrectomy when she was 12 months old. Renal biopsy showed minimal change lesions in one patient, while the nephrectomized kidneys showed mild mesangial proliferation and matrix increase in the glomeruli. No tubular dilatation or microcysts were observed in either patient.

Severe hypertension and massive proteinuria in a newborn with renal artery stenosis

Renal vein thrombosis and the congenital nephrotic syndrome have been associated with nephrotic-range proteinuria/nephrotic syndrome and hypertension in the newborn period. We describe a newborn with severe hypertension and proteinuria secondary to unilateral renal artery stenosis. Proteinuria completely disappeared with blood pressure control (with sodium nitroprusside and an angiotensin-converting enzyme inhibitor). Although renin was not measured, we speculate that proteinuria might have been induced by a high renin state, and was controlled by the angiotensin-converting enzyme inhibitor.

Podocyte differentiation and hereditary proteinuria/nephrotic syndromes

The study of familial nephrotic syndromes (NS) and the analysis of murine models of glomerular diseases resulted in major progresses in the knowledge of podocyte physiology and pathology. Numerous proteins participating in the composition of the slit diaphragm region have been identified. The importance of several of them (nephrin, podocin, CD2AP, and Neph1) in the maintenance of the glomerular filtration barrier has been demonstrated by the occurrence of massive proteinuria when they are defective. The role of the cytoskeleton has been revealed by the development of proteinuria/NS in patients with ACTN4 mutation and the occurrence of early and severe NS in alpha-actinin-4-deficient mice. Given the genetic heterogeneity of familial NS and the many other genes to be identified, further insights in the molecular basis of the role of the podocyte in the maintenance of the glomerular filtration barrier may be expected in the near future.

Proteinuria and prenatal diagnosis of congenital nephrosis in fetal carriers of nephrin gene mutations

High concentrations of alpha-fetoprotein (AFP) are used for prenatal diagnosis of the Finnish type of congenital nephrotic syndrome (NPHS1). We investigated the validity of this test. We retrospectively established fetal NPHS1 genotype and assessed renal pathology in 21 pregnancies that had been terminated because of raised concentrations of AFP in amniotic fluid. 12 fetuses were homozygous and nine were heterozygous (carriers) for NPHS1 mutations. Raised concentrations of AFP and similar proteinuric features in fetal kidneys were seen in both groups, indicating that these signs are unreliable for prenatal diagnosis of congenital nephrosis. We strongly recommend the use of mutation analysis of the NPHS1 gene to confirm the AFP results in prenatal diagnosis of NPHS1.

Congenital nephrotic syndrome (NPHS1): features resulting from different mutations in Finnish patients

BACKGROUND

Congenital nephrotic syndrome (NPHS1) is a rare disease inherited as an autosomally recessive trait. The NPHS1 gene mutated in NPHS1 children has recently been identified. The gene codes for nephrin, a cell-surface protein of podocytes. Two mutations, named Fin-major and Fin-minor, have been found in over 90% of the Finnish patients. In this study, we correlated the NPHS1 gene mutations to the clinical features and renal findings in 46 Finnish NPHS1 children.

METHODS

Clinical data were collected from patient files, and kidney histology and electron microscopy samples were re-evaluated. The expression of nephrin was studied using immunohistochemistry, Western blotting, and in situ hybridization.

RESULTS

Nephrotic syndrome was detected in most patients within days after birth regardless of the genotype detected. No difference could be found in neonatal, renal, cardiac, or neurological features in patients with different mutations. Nephrin was not expressed in kidneys with Fin-major or Fin-minor mutations, while another slit diaphragm-associated protein, ZO-1, stained normally. In electron microscopy, podocyte fusion and podocyte filtration slits of various sizes were detected. The slit diaphragms, however, were missing. In contrast to this, a nephrotic infant with Fin-major/R743C genotype expressed nephrin in kidney had normal slit diaphragms and responded to therapy with an angiotensin-converting enzyme inhibitor and indomethacin.

CONCLUSIONS

The most common NPHS1 gene mutations, Fin-major and Fin-minor, both lead to an absence of nephrin and podocyte slit diaphragms, as well as a clinically severe form of NPHS1, the Finnish type of congenital nephrotic syndrome.

Proteinuria in congenital nephrotic syndrome of the Finnish type

The pattern of urinary protein excretion was followed for 2 to 19 months in 15 children with the congenital nephrotic syndrome of the Finnish type. The duration of the disease and the renal histopathological changes were correlated with the urinary total protein and albumin excretion, the sieving coefficients of five proteins, the selectivity angle based on relative clearances of four proteins, and the excretion of beta-2-microglobulin. Total urinary protein excretion increased with time; in general, the proteinuria was of glomerular type and highly selective. With advancing histological lesions selectivity declined corresponding to the increases in individual sieving coefficients, and there were signs of secondary tubular impairment as shown by increased beta-2-microglobulin excretion. Of the histopathological changes, tubular atrophy correlated best with the various measures of proteinuria. The findings support the concept of a primary glomerular disease with secondary tubular injury.

Mechanisms by which amniotic-fluid alpha-fetoprotein may be increased in fetal abnormalities

Assuming that urination is the principle route by which alpha-fetoprotein (A.F.P.) passes into the amniotic fluid from the normal fetus, and that A.F.P. is mainly degraded by a process of fetal swallowing and digestion, 4 possible mechanisms by which amniotic-fluid A.F.P. is increased by fetal abnormalities are postulated.(1) Amniotic-fluid A.F.P. is increased in open neural-tube defects by leakage of A.F.P. from fetal serum and cerebrospinal fluid.(2) In exomphalos exposure of blood-vessels in the extruding viscera permits transudation of A.F.P. into the amniotic fluid.(3) In nephrosis, fetal proteinuria increases amniotic-fluid A.F.P.(4) Impaired fetal swallowing or digestion would account for increased amniotic-fluid A.F.P. in congenital malformations of the orogastrointestinal tract.