Treating IgA nephropathy

Application of Oxford classification, and overexpression of transforming growth factor-β1 and immunoglobulins in immunoglobulin A nephropathy: correlation with World Health Organization classification of immunoglobulin A nephropathy in a Chinese patient cohort

Immunoglobulin A nephropathy (IgAN) is characterized by the qualitative abnormality of immunoglobulin A (IgA) in circulation and deposits of IgA in the renal mesangium. Transforming growth factor β1 (TGF-β1) plays a key role in fibrogenesis and the progression of renal damage. This study aimed to investigate the clinicopathologic data on IgAN in northeastern China and the presence of TGF-β1, total IgA, and secretory IgA in the glomeruli and sera, as well as changes in galactose-deficient IgA1 in the serum. We investigated the clinicopathologic data of 1050 cases of IgAN diagnosed in a single center over 13 years. We then assessed the concentrations of TGF-β1 and immunoglobulins in the serum of 100 patients with IgAN and 56 healthy control subjects by enzyme-linked immunosorbent assay, and investigated their presence in the glomeruli by immunofluorescence and reverse transcriptase-polymerase chain reaction. From our data, 76.17% of the IgAN cases belonged to classes I and II according to the World Health Organization classification, representing the early stage. Compared with other studies, we found significantly lower frequencies of segmental glomerulosclerosis (27.71%) but higher frequencies of endocapillary proliferation (50.67%), and a similar proportion of mesangial hypercellularity (68.48%) and tubular atrophy/interstitial fibrosis (moderate, 17.81%; severe, 1.52%) in the northeastern Chinese cohort. There was an increased presence of TGF-β1 and immunoglobulins in the serum and glomeruli of IgAN, which correlates with the progression of pathologic classification. The pathologic variables of the Oxford classification correlated significantly with the WHO classifications. TGF-β1 and immunoglobulins could be used as biomarkers of IgAN pathogenic mechanisms, acting as important adjuncts to the original Oxford Classification.

Comparison of inhibitors of renin-angiotensin-aldosterone system (RAS) and combination therapy of steroids plus RAS inhibitors for patients with advanced immunoglobulin A nephropathy and impaired renal function

BACKGROUND

The adaptation of steroid therapy and the effect of renin-angiotensin-aldosterone system inhibitors (RASIs) for advanced immunoglobulin A nephropathy (IgAN) patients with impaired renal function are still controversial.

METHODS

We divided 63 IgAN patients with an estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73 m(2) and proteinuria ≥ 0.5 g/day into two groups: the RASI group (RASI, n = 33), treated with RASIs alone; and the combination group (COMBI, n = 30), treated with corticosteroids and RASIs. We analyzed the clinical and histological background, renal survival rate, and the risk factors for progression.

RESULTS

Renal function (mean eGFR: COMBI 46.4 vs. RASI 47.0 ml/min/1.73 m(2)), the amount of proteinuria (median: COMBI 1.39 vs. RASI 1.17 g/g creatinine) and histological backgrounds were not significantly different between the groups, but urinary red blood cells (U-RBCs) were significantly higher in the COMBI group than in the RASI group (median: COMBI 30.0 vs. RASI 10.0 counts/high-power field, P = 0.0171). The serial change in proteinuria did not differ until 5 years after treatment, but U-RBCs were significantly decreased in both groups (P < 0.0001), and eGFR was significantly decreased in the RASI group (P < 0.001) but not in the COMBI group. The results for each year after treatment did not differ significantly between both groups. The renal survival rate was not significantly different between the groups. There was no independent risk factor for progression by Cox regression analysis.

CONCLUSION

Combination therapy with steroids and RASIs was not superior to monotherapy with RASIs for advanced IgAN with impaired renal function.

Oral calcitriol for reduction of proteinuria in patients with IgA nephropathy: a randomized controlled trial

BACKGROUND

Vitamin D has shown efficacy in the reduction of proteinuria in patients with chronic kidney disease. This study aimed to determine the effect of calcitriol on urinary protein excretion in patients with immunoglobulin A (IgA) nephropathy.

STUDY DESIGN

Open-label, non-placebo-controlled, randomized study.

SETTING & PARTICIPANTS

50 patients with IgA nephropathy were enrolled. The main criterion for inclusion was urinary protein excretion >0.8 g/d after renin-angiotensin system-inhibitor treatment for at least 3 months.

INTERVENTION

Patients were randomly assigned (1:1) to receive 2 doses (0.5 μg) of calcitriol per week or no treatment for 48 weeks.

OUTCOMES

The primary end point was to compare change in 24-hour urinary protein excretion from baseline to last measurement during treatment.

MEASUREMENTS

Every 8 weeks, there was measurement of 24-hour urinary protein excretion, serum calcium, serum phosphorus, serum creatinine, and intact parathyroid hormone.

RESULTS

Measurement of the primary end point showed changes in urinary protein excretion of +21% (from 1.29 to 1.58 g/24 h; 95% CI, -9% to +52%) in the control group and -19% (from 1.60 to 1.30 g/24 h; 95% CI, -42% to +4%) in the calcitriol-treated group. There was a significant decrease in proteinuria in the calcitriol-treated group compared with the control group (difference between groups, 41%; 95% CI, 5%-79%; P = 0.03). The secondary end point of achieving at least a 15% decrease in proteinuria was attained by 7 of 24 (29%) controls and 17 of 26 (65%) of those treated with calcitriol (P = 0.02). No significant differences were observed in decrease in estimated glomerular filtration rate and change in blood pressure between the 2 groups. The incidence of recorded adverse events was similar between the 2 groups.

LIMITATIONS

Small and non-placebo-controlled study.

CONCLUSIONS

The addition of calcitriol to a renin-angiotensin system inhibitor resulted in a safe decrease in proteinuria in patients with IgA nephropathy.

Drug targeting using OX7-immunoliposomes: correlation between Thy1.1 antigen expression and tissue distribution in the rat

OX7 monoclonal antibody F((ab')2) fragments directed against Thy1.1 antigen can be used for drug targeting by coupling to the surface of drug-loaded liposomes. Such OX7-conjugated immunoliposomes (OX7-IL) were used recently for drug delivery to rat glomerular mesangial cells, which are characterized by a high level of Thy1.1 antigen expression. In the present study, the relationship between OX7-IL tissue distribution and target Thy1.1 antigen localization in different organs in rat was investigated. Western blot and immunohistofluorescence analysis revealed a very high Thy1.1 expression in brain cortex and striatum, thymus and renal glomeruli. Moderate Thy1.1 levels were observed in the collecting ducts of kidney, lung tissue and spleen. Thy1.1 was not detected in liver and heart. There was a poor correlation between Thy1.1 expression levels and organ distribution of fluorescence- or (14)C-labeled OX7-IL. The highest overall organ density of OX7-IL was observed in the spleen, followed by lung, liver and kidney. Heart and brain remained negative. With respect to intra-organ distribution, a localized and distinct signal was observed in renal glomerular mesangial cells only. As a consequence, acute pharmacological (i.e. toxic) effects of doxorubicin-loaded OX7-IL were limited to renal glomeruli. The competition with unbound OX7 monoclonal antibody F((ab')2) fragments demonstrated that the observed tissue distribution and acute pharmacological effects of OX7-IL were mediated specifically by the conjugated OX7 antibody. It is concluded that both the high target antigen density and the absence of endothelial barriers are needed to allow for tissue-specific accumulation and pharmacological effects of OX7-IL. The liposomal drug delivery strategy used is therefore specific toward renal glomeruli and can be expected to reduce the risk of unwanted side effects in other tissues.

IgACE: A Placebo-Controlled, Randomized Trial of Angiotensin-Converting Enzyme Inhibitors in Children and Young People with IgA Nephropathy and Moderate Proteinuria

This European Community Biomedicine and Health Research-supported, multicenter, randomized, placebo-controlled, double-blind trial investigated the effect of an angiotensin-converting enzyme inhibitor (ACE-I) in children and young people with IgA nephropathy (IgAN), moderate proteinuria (>1 and <3.5 g/d per 1.73 m(2)) and creatinine clearance (CrCl) >50 ml/min per 1.73 m(2). Sixty-six patients who were 20.5 yr of age (range 9 to 35 yr), were randomly assigned to Benazepril 0.2 mg/kg per d (ACE-I) or placebo and were followed for a median of 38 mo. The primary outcome was the progression of kidney disease, defined as >30% decrease of CrCl; secondary outcomes were (1) a composite end point of >30% decrease of CrCl or worsening of proteinuria until > or =3.5 g/d per 1.73 m(2) and (2) proteinuria partial remission (<0.5 g/d per 1.73 m(2)) or total remission (<160 mg/d per 1.73 m(2)) for >6 mo. Analysis was by intention to treat. A single patient (3.1%) in the ACE-I group and five (14.7%) in the placebo group showed a worsening of CrCl >30%. The composite end point of >30% decrease of CrCl or worsening of proteinuria until nephrotic range was reached by one (3.1%) of 32 patients in the ACE-I group, and nine (26.5%) of 34 in the placebo group; the difference was significant (log-rank P = 0.035). A stable, partial remission of proteinuria was observed in 13 (40.6%) of 32 patients in the ACE-I group versus three (8.8%) of 34 in the placebo group (log-rank P = 0.033), with total remission in 12.5% of ACE-I-treated patients and in none in the placebo group (log-rank P = 0.029). The multivariate Cox analysis showed that treatment with ACE-I was the independent predictor of prognosis; no influence on the composite end point was found for gender, age, baseline CrCl, systolic or diastolic BP, mean arterial pressure, or proteinuria.

Immunoliposome Targeting to Mesangial Cells: A Promising Strategy for Specific Drug Delivery to the Kidney

Mesangial cell-mediated nephropathies are a frequent cause of ESRD. Specific drug delivery to mesangial cells might be more effective and better tolerated than existing systemic treatments. Rat mesangial cells are characterized by Thy1.1 antigen expression. Therefore, OX7-coupled immunoliposomes (OX7-IL) were prepared by coupling liposomes with F(ab') fragments of OX7 mAb directed against Thy1.1 antigen. As the glomerular endothelium is fenestrated and no basement membrane separates glomerular capillaries from the mesangium, mesangial cells represent a particularly suitable target for drug delivery by OX7-IL. Therefore, the targeting efficacy of OX7-IL to mesangial cells was investigated. Specific targeting in vitro was obtained, and intravenous injection of OX-7-IL to rats showed a specific targeting of all mesangial cells in both kidneys. OX7-IL showed marked accumulation in the cytoplasm of rat mesangial cells, both in vitro and in vivo. This renal targeting was blocked when free OX7 F((ab')2) fragments were co-administered with OX7-IL. Rats that were given a single intravenous injection of low-dose doxorubicin encapsulated in OX7-IL showed extensive glomerular damage, whereas other parts of the kidney and other organs were spared. Free doxorubicin and the liposomal formulation of this agent had no effect. Thus, immunoliposomes are a very promising delivery system for the treatment of kidney diseases.