Diagnosis and activity assessment of immunoglobulin A nephropathy: current perspectives on noninvasive testing with aberrantly glycosylated immunoglobulin A-related biomarkers.

Immunoglobulin (Ig) A nephropathy (IgAN) is the most common form of glomerular disease worldwide and is associated with a poor prognosis. Thus, development of a curative treatment and strategies for early diagnosis and treatment are urgently needed. Pathological analysis of renal biopsy is the gold standard for the diagnosis and assessment of disease activity; however, immediate and frequent assessment based on biopsy specimens is difficult. Therefore, a simple and safe alternative is desirable. On the other hand, it is now widely accepted that multi-hit steps, including production of aberrantly glycosylated serum IgA1 (first hit), and IgG or IgA autoantibodies that recognize glycan containing epitopes on glycosylated serum IgA1 (second hit) and their subsequent immune complex formation (third hit) and glomerular deposition (fourth hit), are required for continued progression of IgAN. Although the prognostic and predictive values of several markers have been discussed elsewhere, we recently developed a highly sensitive and specific diagnostic method by measuring serum levels of glycosylated serum IgA1 and related IgA immune complex. In addition, we confirmed a significant correlation between serum levels of these essential effector molecules and disease activity after treatment, suggesting that each can be considered as a practical surrogate marker of therapeutic effects in this slowly progressive disease. Such a noninvasive diagnostic and activity assessment method using these disease-oriented specific biomarkers may be useful in the early diagnosis of and intervention in IgAN, with appropriate indication for treatment, and thus aid in the future development and dissemination of specific and curative treatments.

Dietary zinc is a key environmental modifier in the progression of IgA nephropathy.

IgA nephropathy (IgAN) shows diverse epidemiological characteristics, resulting from both genetic and acquired (e.g., environmental) causes. Environmental factors, such as diet or exposure to exogenous antigens, may prescribe the progression or prognosis of IgAN. It remains unclear as to how diet and infection influence susceptibility to IgAN. A relationship, such as Toll-like receptors (TLRs), especially TLR9 and TLR4, was demonstrated between IgAN and pathogen-recognition molecules. Recently, zinc (Zn) was discovered to be involved in various immune-related diseases, affecting B, T, and dendritic cells (DCs). This study investigates the relationship between dietary Zn and IgAN development in IgAN-prone mice. Seven-week-old IgAN-prone mice were divided into low, normal, and high Zn diet groups. To assess exogenous pathogen-mediated immune responses, lipopolysaccharide (LPS) was nasally administered. The activity of IgAN was biochemically and pathologically evaluated during the disease course. We also examined in vitro IgA production in spleen cells or in combinations of cocultured B, T, and DCs under various Zn conditions with or without LPS. Dietary conditioning with Zn affected serum immunoglobulins and urinary albumin levels, and mesangial deposition of IgA and IgG. Zn deficiency is associated with IgAN progression through the activation of the TLR4/TIR-domain-containing adapter-inducing interferon-ß (TRIF), but not the TLR9, in DCs. Zn supplementation prevented disease aggravation. Our findings indicate that immune conditioning with dietary Zn alters nephritogenic IgA production after mucosal infection.

Serum levels of galactose-deficient immunoglobulin (Ig) A1 and related immune complex are associated with disease activity of IgA nephropathy.

BACKGROUND: The primary abnormal manifestation in immunoglobulin A nephropathy (IgAN) is recurring bouts of hematuria with or without proteinuria. Although immunohistochemical analysis of renal biopsy tissue remains the gold standard not only for diagnosis but also for evaluating the activity of IgAN, new sensitive and reasonably specific noninvasive tests are emerging to guide therapeutic strategy applicable to all stages of IgAN. The present study examined serum levels of galactose-deficient IgA1 (Gd-IgA1) and its immune complex (IgA/IgG-IC) as noninvasive markers for the disease activity. METHODS: We enrolled 50 IgAN patients (male 40 %, median age 37 years) showing complete or partial clinical remission after steroid pulse therapy with tonsillectomy (TSP) whose clinical data and serum could be followed up for 3-5 years. RESULTS: Cross-sectional analysis revealed that the degree of hematuria and proteinuria were significantly associated with levels of Gd-IgA1 and levels of IgA/IgG-IC. Longitudinal analysis further showed that from the group of 44 patients with heavy hematuria before TSP, 31 patients showed complete disappearance of hematuria (group A), but the remaining patients did not (group B). Although the levels of Gd-IgA1 and IgA/IgG-IC in the two groups before TSP were similar, percentage decrease of Gd-IgA1 and IgA/IgG-IC levels in group A was significantly higher than in group B. CONCLUSION: Disease activity of IgAN assessed by hematuria and proteinuria correlated with serum levels and changes of Gd-IgA1 and IgA/IgG-IC. These new noninvasive disease activity markers can be useful for future activity scoring system and guiding therapeutic approaches.

Protective effect of an immune-modulating diet comprising whey peptides and fermented milk products on indomethacin-induced small-bowel disorders in rats.

BACKGROUND & AIMS: An immune-modulating diet (IMD) comprising whey peptides and fermented milk products has produced anti-inflammatory effects in various animal models and has been employed in peri-operative nutritional care. It was investigated the effectiveness of an immune-modulating diet on indomethacin-induced small-bowel disorders. METHODS: Six-week-old male Sprague-Dawley rats were fed a control diet (control group) or an IMD (IMD group) for 14 days. Thereafter, they were injected with 10 mg/kg/day indomethacin for 2 consecutive days to induce small-bowel disorders. The excretion rate of phenolsulfonphthalein in the urine, bacterial translocation (BT) in the mesenteric lymph nodes (MLNs) and liver, the number of ulcers that formed in the small bowel, and the concentration of cytokines were measured. RESULTS: The IMD group exhibited significant suppression of increased permeability of the mucosa and decreased BT in the MLNs and liver compared with the control group. The immune-modulating diet group also showed a decrease in ulcer formation and lower concentrations of IL-6 in the ileal tissues compared with the control group. CONCLUSIONS: These data suggest that the IMD had a protective effect on the small bowel, and may be effective nutritional care in patients with perioperative damage to the small intestine and gastrointestinal disorders.

Development of a model of early-onset IgA nephropathy.

ddY mice spontaneously develop IgA nephropathy (IgAN) with a variable age of disease onset. Establishing a model with early-onset IgAN could aid the investigation of mechanisms that underlie the pathogenesis of this disease. On the basis of histologic grading in serial biopsies, we previously classified ddY mice into early-onset, late-onset, and quiescent groups. Here, we selectively mated mice with the early-onset phenotype for >20 generations and established "grouped ddY" mice that develop IgAN within 8 weeks of age. Similar to human IgAN, the prognosis was worse for male mice than females. These mice homogeneously retained genotypes of four marker loci previously associated with the early-onset phenotype, confirming a close association of these loci with early-onset IgAN in ddY mice. Grouped ddY mice comprised two sublines, however, which had distinct genotypes at a susceptibility locus for high serum IgA levels, which maps within the Ig heavy-chain gene complex. The subline bearing the Igh-2(a) IgA allotype had a more rapid course of fatal disease and lower oligosaccharide content, suggesting that aberrant IgA glycosylation may promote the progression of murine IgAN. Taken together, these data indicate that grouped ddY mice may be a useful model for the identification of susceptibility genes and the underlying molecular mechanisms involved in the pathogenesis of human IgAN.

A newly designed enteral formula containing whey peptides and fermented milk product protects mice against concanavalin A-induced hepatitis by suppressing overproduction of inflammatory cytokines.

BACKGROUND & AIMS: We previously reported that whey protein derived from cow milk suppressed inflammation in a variety of animal models. We developed a newly designed enteral formula using peptides prepared from whey protein and fermented milk product and investigated its ability to suppress inflammation in concanavalin A-induced hepatitis in mice. METHODS: C57BL/6 mice were fed a standard formula, AIN-93M, or enteral formula for 14 days, and then were intravenously administered concanavalin A. Inflammatory cytokines in plasma, liver, and spleen and markers of hepatic function in plasma were assessed at various time points. Livers were assessed for necrosis and apoptosis. RESULTS: After concanavalin A treatment, plasma aspartate aminotransaminase, alanine aminotransferase, TNF-α, IL-6, and IFN-γ levels were significantly lower in mice fed enteral formula than in those fed standard formula or AIN-93M. Liver TNF-α and IFN-γ, and spleen IL-6 and IFN-γ levels were lower in enteral formula-fed mice than in standard formula-fed mice 2 h after concanavalin A treatment. Necrosis and apoptosis were suppressed in the livers of enteral formula-fed mice. CONCLUSIONS: The new enteral formula is a potent novel immune-modulating diet that prevents aggravation of local inflammation by modulating systemic cytokine levels.

Reevaluation of the mucosa-bone marrow axis in IgA nephropathy with animal models.

Impaired immune regulation along the 'mucosa-bone marrow axis' has been postulated to play an important role in the pathogenesis of IgA nephropathy (IgAN). Animal models have allowed us to study such changes in detail. Recently, we established several useful animal models, including IgAN-prone mice. Using these animal models, our group is approaching the underlying mechanisms by which bone marrow and mucosal cell interrelate and finally induce this disease. Accumulating evidence from these approaches suggests that there is dysregulation of innate and cellular immunity in IgAN resulting in changes in the mucosal immune system. These changes appear to be closely linked to disruption of mucosal tolerance, resulting in abnormal priming and dissemination of cells to sites such as the bone marrow where they are responsible for synthesis of nephritogenic IgA. Our clinical studies further support these ideas and indicate that the tonsils may be a major mucosal priming site in human IgAN. In addition, our findings also suggest clinical application of nephritogenic IgA (IgA1) as a biological marker and possible future treatment strategies that focus on manipulating the priming and dissemination of these memory cells in order to prevent the appearance of nephritogenic IgA (IgA1) in the systemic compartment.

Hepatoprotective effects of whey protein on D-galactosamine-induced hepatitis and liver fibrosis in rats.

The hepatoprotective effects of whey protein on two injections of D-galactosamine (300 mg/kg, i.p.) were investigated in rats fed a modified AIN-93M diet formulated with a protein source of casein or whey for 16 d. The whey protein-containing diet clearly suppressed an increase in plasma alanine and aspartate aminotransferase activity, lactate dehydrogenase and bilirubin, which are hepatitis markers, and also hyaluronic acid, a fibrosis marker. In addition, it suppressed histopathological signs of portal fibrosis, bile duct proliferation, and perivenular sclerosis. These results suggest that supplementation with whey protein can help prevent the development of hepatitis and portal fibrosis.

Terfenadine induces thymocyte apoptosis via mitochondrial pathway.

The treatment of rat thymocytes with 10 microM terfenadine resulted in a significant increase in DNA fragmentation. The DNA fragmentation induced by terfenadine was dependent on its concentration and incubation time. In terfenadine-treated cells, the translocation of phosphatidylserine from the inside of plasma membrane to the outside, an early event of the apoptotic process, and chromatin condensation, the morphological characterization of apoptotic cell death, were observed. Terfenadine stimulated caspase-8, -9 and -3-like activities in an incubation time-dependent manner in thymocytes. The active forms of caspase-3 and -9 were detected in the extract from terfenadine-treated cells by immunoblotting analysis using specific antibodies to caspases, but active caspase-8 was not found in this fraction. Decrease in mitochondrial membrane potential and the release of cytochrome c from mitochondria to cytosol were observed in terfenadine-treated thymocytes. These results suggest that terfenadine induces apoptosis in rat thymocytes via mitochondrial pathway.