In the kidney, proteins filtered through glomeruli are reabsorbed by endocytosis along the proximal tubules to avoid renal loss of large amounts of proteins. Recently, neonatal Fc receptor (FcRn), which is involved in the transport of IgG across several epithelial and endothelial cells, was reported to be expressed in renal proximal tubular epithelial cells (RPTECs). However, there has been no direct evidence for receptor-mediated endocytosis of IgG in human RPTECs. To explore physiological roles of FcRn in the proximal tubules, we used the human RPTECs to examine IgG transport. FcRn was expressed in RPTECs and physically associated with beta(2)-microglobulin, preserving the capacity of specific pH-dependent IgG binding. Human IgG was bound to the cell surface of RPTECs in a pH-dependent manner. The human IgG transport assay revealed that receptor-mediated transepithelial transport of intact IgG in RPTECs is bidirectional and that it requires the formation of acidified intracellular compartments. With the use of double immunofluorescence, the internalized human IgG was marked in cytoplasm of RPTECs and colocalized with FcRn. These data define the mechanisms of FcRn-associated IgG transport in RPTEC monolayers. It was suggested that the intact pathway for human IgG transepithelial transport may avoid lysosomal degradation of IgG.

Background. Patients with IgA nephropathy (IgAN) have an increased amount of abnormally O-glycosylated IgA1 in circulation, in glomerular deposits and produced by tissue cells in vitro. Although increased production of Th2 cytokines by peripheral blood lymphocytes and a functional abnormality of core 1 β1,3-galactosyltransferase (C1β3Gal-T) have been proposed as mechanisms underlying pathogenesis of IgAN, they are still obscure and are not connected.Methods. To clarify the effect of T-cell cytokines, we analysed the mRNA levels of C1β3Gal-T and its molecular chaperone Cosmc, C1β3Gal-T activity and subsequent O-glycosylation of IgA1 in a human B-cell line stimulated with these cytokines. The surface IgA1-positive human B-cell line was cultured with recombinant human IFN-γ, IL-2, IL-4 or IL-5. The production and glycosylation of IgA1 were determined by sandwich ELISA and enzyme-linked lectin binding assay, respectively. The mRNA levels of C1β3Gal-T and Cosmc were quantitatively measured by real-time PCR. C1β3Gal-T activity was analysed using high-performance liquid chromatography.Results. IgA1 production by IL-4-stimulated cells was significantly higher than controls or after IFN-γ or IL-5. The terminal glycosylation of secreted IgA1 was altered in response to IL-4. IL-4 stimulation significantly decreased the mRNA levels of both C1β3Gal-T and Cosmc and of C1β3Gal-T activity. IL-4 stimulation was clearly blocked by recombinant human IL-4 soluble receptor.Conclusions. It appears that Th2 cytokine IL-4 may play a key role in controlling glycosylation of the IgA1 hinge region.

We determined the relationship between the levels of serum cystatin C or creatinine (s-Cr) and the grade of creatinine clearance (CCr) in patients with various glomerular diseases. Serum samples from 96 patients with glomerular diseases were obtained from our hospital. The levels of serum cystatin C were measured using the Dade Behring Cystatin C assay with the automated Dade Behring Nephelometer II (BNII). CCr levels were classified into six groups according to the Guidelines of the Japanese Society of Nephrology as follows: grade 1 (normal renal function); grade 2 (slight decrease of renal function); grade 3 (moderate decrease of renal function); grade 4 (severe decrease of renal function); grade 5 (renal failure), and grade 6 (uremia). The mean levels of serum cystatin C in grade 3 patients were significantly higher than those in grade 1. The mean levels of serum cystatin C in grades 4, 5 and 6 patients were also significantly higher than those in grade 1. However, the mean levels of serum Cr in grade 3 patients were not significantly higher than those in grade 1. The levels of s-Cr in grades 4, 5 or 6 patients were significantly higher than those in grade 1. In this study, an increase of serum cystatin C levels occurred earlier than that of s-Cr in various glomerular diseases. It appears that the levels of serum cystatin C may provide early prognostic marker of patients with various glomerular diseases rather than the levels of s-Cr.

The aim of the present study was to determine if treatment with an oral adsorbent (AST-120, Kremezin^®) might decrease the urinary albumin excretion and serum indoxyl sulfate (s-IS), and prevent glomerular sclerosis in early-stage renal failure, i.e. 0.9–1.2 mg/dl of serum creatinine (s-Cr) and 60–95 mg/dl of blood urea nitrogen (BUN), in subtotal (3/4) nephrectomized rats. Levels of s-Cr and s-IS in the AST-120-treated rats were significantly lower than those in the untreated control rats. The AST-120-treated rats showed an increase of creatinine clearance. Urinary protein and indoxyl sulfate excretion in the AST-120-treated rats were also significantly lower than those in the untreated control rats. The ratio of glomerular tuft area to the area of Bowman’s capsules (GT/BC) in the AST-120-treated rats was significantly lower than that in the untreated control rats. The degree of glomerular sclerosis and tubulointerstitial fibrosis in the AST-120-treated rats was significantly lower than that in the untreated control rats. Furthermore, there was a significant relationship among the degree of GT/BC, glomerular sclerosis, tubulointerstitial fibrosis and the levels of urinary protein excretion. It appears that AST-120 might decrease the accumulation of s-Cr and s-IS, and prevent glomerular sclerosis in early stage renal failure in the subtotal nephrectomized rats.

Subacute bacterial endocarditis (SBE) associated with antiproteinase-3 antineutrophil cytoplasmic antibodies (PR3-ANCA) has previously been reported in 10 cases of Streptococcus viridans and in 1 case of Escherichia faecalis infection. Most of these patients had hypocomplementemia and were positive for several autoantibodies. The infections in most of these patients showed good responses to antibiotic treatment. We report three patients with ANCA-positive SBE, which was induced by attenuated slow-growing intracellular pathogens; these patients had severe complications, such as acute kidney injury, cerebral embolism, and aortic valve destruction.

Although GFR-estimating equations are useful for estimating GFR accurately, they pose a risk of overestimation of kidney function in patients with decreased GFRor a poor physique.

We conclude that different mesangial cell responses to this common mucosal viral pathogen might influence the severity of IgAN in our model system.

Background/Aims: Polymyxin B-immobilized fiber (PMX-F) treatment is reported to be safe and effective in patients with severe sepsis and septic shock. The aim of the present study was to determine whether plasma levels of interleukin (IL)-18, which is linked with sepsis, are associated with plasma endotoxin levels and sepsis-related scores and whether PMX-F treatment affects these variables in patients with septic shock. Patients and Methods: Twenty-six patients with septic shock (15 men and 11 women; mean age 56.5 years) and 20 age-matched healthy subjects (12 men and 8 women; mean age 54.0 years) were included in this study. Septic shock patients were divided into 2 groups: a PMX-F treatment group (9 men and 5 women; mean age 57.5 years) and a conventional treatment group (7 men and 5 women; mean age 55.3 years). Standard supportive care was continued without change during PMX-F treatment. Plasma endotoxin, plasma IL-18, and clinical variables were measured before, immediately after the first and second PMX-F treatment, and the following day. Results: The plasma IL-18 levels were significantly higher in septic shock patients (1,320 ± 360 pg/ml) than in healthy volunteers (140 ± 60 pg/ml; p < 0.001). The IL-18 level was significantly correlated with the plasma endotoxin level (p < 0.001), the Acute Physiology and Chronic Health Evaluation II score (p < 0.01), the Sepsis Severity Score (p < 0.01), the number of failed organs (p < 0.01), and the Goris score (p < 0.01). PMX-F treatment reduced the plasma endotoxin and IL-18 levels significantly after the first treatment (p < 0.05), after the second treatment (p < 0.01), and on the following day (p < 0.001). However, these variables did not change significantly during conventional treatment. Conclusions: IL-18 may be associated with the severity of septic shock, and PMX-F treatment is effective in reducing the IL-18 level in patients with septic shock.