Prevalence of alpha1-antitrypsin phenotypes in patients with IgA nephropathy.

BACKGROUND: alpha1-antitrypsin (AAT) is the main protease inhibitor in the blood. Several different AAT phenotypes exist. The most common variant is the MM phenotype, which is also associated with normal AAT levels. The less common phenotypes with Z and S variants are associated with low AAT levels. AAT deficiency is a risk factor for pulmonary emphysema, liver impairment and some immune-mediated diseases, some of which are also associated with IgA nephropathy (IgAN). In fact, liver impairment resulting from AAT deficiency may directly contribute to renal abnormalities resembling IgAN. PATIENTS AND METHODS: We investigated AAT phenotype and AAT levels in 100 IgAN patients who did not have end-stage liver disease. Fifteen patients in our sample had secondary IgAN. We also tested for the presence of renal deposition of AAT in patients heterozygous for AAT variants as well as in a randomly chosen group of patients with MM phenotype. We checked for any association between AAT phenotype and the progression of IgAN as well as the prevalence of diseases associated with IgAN (i.e. secondary IgAN). RESULTS: Twelve patients in our sample were heterozygous for AAT variants. Phenotypes were MZ in 5 patients, MS in 3, MF in 1, ML in 2 and ME in 1 patient. AAT levels were lower in these 12 patients than in those homozygous for the M variant (1.17+/-0.46 vs. 1.44+/-0.34 g/l, p < 0.05). We found renal deposition of AAT in 2 heterozygous patients and in 1 of the 12 patients which were randomly chosen. End-stage renal (ESRF) failure developed in 3 of the 12 heterozygous patients and in 6 of the 88 homozygous patients (p = 0.07) during the follow-up. The prevalence of heterozygosity was significantly higher in patients with secondary IgAN than in those with primary IgAN ((5/15 vs. 7/85; p < 0.02). CONCLUSIONS: AAT phenotype is not associated with the risk of primary IgA nephropathy, but might have an impact on disease outcome as well as on the risk of secondary IgAN.

Expression and activity of the Ca(2+)-atpase enzyme in human neonatal erythrocytes.

The plasma membrane Ca(2+)-ATPase (PMCA) is one of the main regulators of Ca(2+) homeostasis. We studied the perinatal alteration of the abundance and the activity of PMCA molecules in human erythrocytes in pre-term and full-term neonates and children at the age of 1-4 years. The lower abundance of the 4b isoform was associated with lower enzyme activity in full-term neonates compared to children. Although the number of PMCA molecules was higher in pre-term neonates, their total PMCA activities were identical to those of full-term neonates. Our findings suggest that the abundance of PMCA molecules changes during the perinatal development. The same activity at higher enzyme molecule numbers might indicate a potential immaturity of the enzyme in the pre-term infant.

Abundance and activity of Ca2+-ATPase in hypercalciuric children.

The plasma membrane Ca2+-ATPase (PMCA) is one of the main regulators of cell Ca2+ homeostasis. The aim of our study was to determine whether the abundance and activity of PMCA are altered in erythrocytes of children with idiopathic hypercalciuria. Twenty-four children with idiopathic hypercalciuria (13 girls and 11 boys, mean age 10.6+/-4.8 years; mean urinary calcium concentration 0.85+/-0.20 mmol/mmol creatinine) and 30 healthy age-matched children were enrolled. PMCA protein abundance was determined by Western blot analysis. Enzyme activity was determined spectrophotometrically. The abundance of PMCA did not differ in hypercalciuric patients from that of control subjects (98+/-22% vs 100+/-18%). Moreover, the activity was not different between the studied groups (3141+/-1494 vs 2953+/-780 nmol ATP/mg protein/h). The extent of hypercalciuria did not correlate with enzyme abundance or activity. Assuming that erythrocytes may reflect the renal tubular transporting processes, our data suggest that other Ca2+-transport mechanisms than PMCA might be involved in the development of idiopathic hypercalciuria in children.

Bidirectional communication between histamine and cytokines.

Histamine plays fundamental roles in numerous immune reactions. In addition to its well-characterized effects in the acute inflammatory and allergic responses, histamine also influences the expression and actions of several cytokines. The interaction between histamine and the cytokines is bidirectional, since some cytokines were found to modulate the production and release of histamine as well. Because several pharmacological agents that modulate the actions of histamine (e.g. antihistamines) are widely used in the treatment of various human diseases (allergy, peptic ulcer etc.), this complex interaction could have general medical relevance too, but the current situation appears to be rather controversial and further studies are needed to elucidate these sophisticated interactions more precisely.

Improved strategy for molecular genetic diagnostics in juvenile nephronophthisis.

Juvenile or type 1 nephronophthisis (NPH1), an autosomal recessive cystic kidney disease, represents the most common genetic cause of end-stage renal disease in the first two decades of life. Because the disease is caused by large homozygous deletions of the NPHP1 gene in approximately 66% of patients with nephronophthisis, molecular genetic testing offers a method for the definite diagnosis of NPH1 and avoids the invasive procedure of renal biopsy. We recently developed an algorithm for molecular genetic diagnosis of NPH1 that efficiently detects homozygous deletions. However, a major limitation remained for the detection of heterozygous deletions that cause NPH1 in combination with point mutations at the other NPHP1 allele. Because a partial sequence from the NPHP1 region recently became available through the Human Genome Projects, we exploited this information to develop novel polymorphic markers from this genetic region for the detection of heterozygous deletions of NPHP1, thus bridging the diagnostic gap. Five novel polymorphic microsatellites positioned within the large common NPHP1 deletion were generated. Two multiplex polymerase chain reaction sets using two and three polymorphic markers from the NPHP1 deletion region together with one positive control marker allowed four different diagnostic problems to be solved in one diagnostic setup: (1) detection of the classic homozygous deletion of NPH1, (2) detection of a rare smaller homozygous deletion of NPH1, (3) testing for a heterozygous deletion, and (4) potential exclusion of linkage to NPHP1. The newly generated multiplex marker sets will greatly enhance the efficacy of molecular diagnostics in NPH through improved detection of heterozygous deletions.

Both interferon (IFN)alpha and IFNgamma inhibit histidine decarboxylase expression in the HT168 human melanoma cell line.

OBJECTIVE: Histamine plays an important role in a series of processes including inflammation, allergy, gastric acid secretion, neurotransmission, embryogenesis and in various tumours. Histidine decarboxylase (HDC), the enzyme solely responsible for generation of histamine is expressed in many cells including regenerating and tumour cells. HDC expression is regulated by multiple tissue factors, e.g. various cytokines and growth hormones. In this study the effect of interferon alpha and interferon gamma on the expression of HDC and on cell proliferation in vitro on melanoma cell line. METHODS: We used recombinant human interferon alpha, interferon gamma and human melanoma cell line HT168. RESULTS: Our data show that both IFNalpha and IFNgamma decreased the HDC mRNA and protein expression, though with dissimilar kinetics. IFNgamma strongly suppresses the proliferation at 72 h, while IFNalpha has a more moderate effect. CONCLUSIONS: Since previously the inhibitory effect of histamine on gene expression of interferon gamma was detected, a reciprocal inhibition between histamine and IFNgamma is proposed.