Fernand Mac-Moune Lai

The Oxford classification of IgA nephropathy: rationale, clinicopathological correlations, and classification

IgA nephropathy is the most common glomerular disease worldwide, yet there is no international consensus for its pathological or clinical classification. Here a new classification for IgA nephropathy is presented by an international consensus working group. The goal of this new system was to identify specific pathological features that more accurately predict risk of progression of renal disease in IgA nephropathy, thus enabling both clinicians and pathologists to improve individual patient prognostication. In a retrospective analysis, sequential clinical data were obtained on 265 adults and children with IgA nephropathy who were followed for a median of 5 years. Renal biopsies from all patients were scored by pathologists blinded to the clinical data for pathological variables identified as reproducible by an iterative process. Four of these variables: (1) the mesangial hypercellularity score, (2) segmental glomerulosclerosis, (3) endocapillary hypercellularity, and (4) tubular atrophy/interstitial fibrosis were subsequently shown to have independent value in predicting renal outcome. These specific pathological features withstood rigorous statistical analysis even after taking into account all clinical indicators available at the time of biopsy as well as during follow-up. The features have prognostic significance and we recommended they be taken into account for predicting outcome independent of the clinical features both at the time of presentation and during follow-up. The value of crescents was not addressed due to their low prevalence in the enrolled cohort.

The Oxford classification of IgA nephropathy: pathology definitions, correlations, and reproducibility

Pathological classifications in current use for the assessment of glomerular disease have been typically opinion-based and built on the expert assumptions of renal pathologists about lesions historically thought to be relevant to prognosis. Here we develop a unique approach for the pathological classification of a glomerular disease, IgA nephropathy, in which renal pathologists first undertook extensive iterative work to define pathologic variables with acceptable inter-observer reproducibility. Where groups of such features closely correlated, variables were further selected on the basis of least susceptibility to sampling error and ease of scoring in routine practice. This process identified six pathologic variables that could then be used to interrogate prognostic significance independent of the clinical data in IgA nephropathy (described in the accompanying article). These variables were (1) mesangial cellularity score; percentage of glomeruli showing (2) segmental sclerosis, (3) endocapillary hypercellularity, or (4) cellular/fibrocellular crescents; (5) percentage of interstitial fibrosis/tubular atrophy; and finally (6) arteriosclerosis score. Results for interobserver reproducibility of individual pathological features are likely applicable to other glomerulonephritides, but it is not known if the correlations between variables depend on the specific type of glomerular pathobiology. Variables identified in this study withstood rigorous pathology review and statistical testing and we recommend that they become a necessary part of pathology reports for IgA nephropathy. Our methodology, translating a strong evidence-based dataset into a working format, is a model for developing classifications of other types of renal disease.

Membranous Nephropathy Related to Hepatitis B Virus in Adults

BACKGROUND The natural course of adult hepatitis B virus (HBV)-related membranous nephropathy in areas where HBV infection is endemic (characterized by vertical and horizontal transmission of HBV in early childhood) has not been fully defined. METHODS We evaluated the clinical features, pathological findings, serologic profiles, therapeutic responses, and prognoses of 21 patients with adult-onset HBV-related membranous nephropathy. The patients were followed for a mean of 60 months (range, 12 to 108). Only patients with evidence of glomerular capillary deposition of hepatitis B e antigen (HBeAg) in a renal-biopsy specimen were included. RESULTS The clinical features and serologic studies suggested that the patients had acquired chronic HBV infection in early childhood; moreover, other causes of membranous nephropathy had been excluded. All were seropositive for hepatitis B surface antigen and had high titers of antibody to hepatitis B core antigen at first clinical presentation. HBeAg was detected in the serum of 17 patients (81 percent), yet only 3 had even slightly increased plasma alanine aminotransferase levels. The clinical response to therapy with interferon alfa was disappointing; only one of the five patients treated had a complete remission with seroconversion to antibody to HBeAg. Contrary to reports of studies in children, spontaneous remission of the nephrotic syndrome or proteinuria was uncommon in the adults with HBV-related membranous nephropathy whom we studied. Proteinuria and HBV antigenemia persisted in untreated patients. During the follow-up period, 29 percent of the patients had progressive renal failure and 10 percent required maintenance dialysis therapy. CONCLUSIONS The course of HBV-related membranous nephropathy in adults in areas where HBV is endemic is not benign. Regardless of treatment, the disease has a slowly but relentlessly progressive clinical course in approximately one third of patients.

The natural history of immunoglobulin a nephropathy among patients with hematuria and minimal proteinuria

PURPOSE To determine the natural history of immunoglobulin (Ig) A nephropathy among patients who presented with hematuria and minimal proteinuria, and factors associated with the development of adverse clinical events, such as proteinuria. SUBJECTS AND METHODS In Hong Kong, all patients who present with isolated hematuria are referred for renal biopsy after urologic diseases are ruled out. We reviewed the clinical course of 72 consecutive patients with histologically confirmed IgA nephropathy who presented with hematuria and minimal proteinuria (0.4 g/day or less). All patients were normotensive and had normal renal function at presentation. Adverse events were defined as proteinuria greater than 1 g per day, hypertension, or impaired renal function (serum creatinine level 120 micromol/L or estimated creatinine clearance < 70 mL per minute). RESULTS The mean (+/- SD) age at presentation was 27 +/- 8 years; 56 (78%) were female. Nine patients (13%) had grade 2 histologic lesions. During a median follow-up of 7 years, 32 patients (44%) developed adverse events: 24 (33%) developed proteinuria of 1 g per day or more, 19 (26%) became hypertensive, and 5 (7%) developed impaired renal function. Another 30 patients (42%) had persistently abnormal urinalysis examinations. Only 10 patients (14%) had complete resolution of hematuria. The median time for progression from proteinuria (> l g/day) to renal impairment was 84 months (range 56 to 132). In a multivariate analysis, age at presentation (relative risk [RR] per 10 years of age = 2.0; 95% confidence interval [CI], 1.2 to 3.4) and histologic grade (grade 2 versus grade 1, RR = 4.5; 95% CI, 1.7 to 12) were independent predictors of developing an adverse event. CONCLUSIONS IgA nephropathy that presents with hematuria and minimal proteinuria is usually a progressive disease. Life-long follow-up with regular monitoring of blood pressure and proteinuria is recommended.

The Oxford IgA nephropathy clinicopathological classification is valid for children as well as adults

To study the predictive value of biopsy lesions in IgA nephropathy in a range of patient ages we retrospectively analyzed the cohort that was used to derive a new classification system for IgA nephropathy. A total of 206 adults and 59 children with proteinuria over 0.5 g/24 h/1.73 m(2) and an eGFR of stage-3 or better were followed for a median of 69 months. At the time of biopsy, compared with adults children had a more frequent history of macroscopic hematuria, lower adjusted blood pressure, and higher eGFR but similar proteinuria. Although their outcome was similar to that of adults, children had received more immunosuppressants and achieved a lower follow-up proteinuria. Renal biopsies were scored for variables identified by an iterative process as reproducible and independent of other lesions. Compared with adults, children had significantly more mesangial and endocapillary hypercellularity, and less segmental glomerulosclerosis and tubulointerstitial damage, the four variables previously identified to predict outcome independent of clinical assessment. Despite these differences, our study found that the cross-sectional correlation between pathology and proteinuria was similar in adults and children. The predictive value of each specific lesion on the rate of decline of renal function or renal survival in IgA nephropathy was not different between children and adults.

Frequent hypermethylation of promoter region of RASSF1A in tumor tissues and voided urine of urinary bladder cancer patients

High frequency loss of 3p21.3 region where RASSF1A located was demonstrated in several tumors. We aimed to investigate the methylation status of RASSF1A and the frequency of LOH in 3p21.3 region in bladder cancer. Three bladder cancer cell lines, 40 cases of bladder TCC and 14 cases of paired voided urine samples were subjected to methylation analysis. By methylation specific PCR, complete methylation of promoter region of RASSF1A gene were detected in cell lines T24 and UMUC3. Demethylation treatment re‐expressed RASSF1A in these 2 cell lines. Methylation of RASSF1A was also detected in 47.5% (19/40) of the TCC cases but not in 6 carcinoma in situ (CIS) or 6 normal urothelium samples. For LOH study, loss of 3p21.3 region was detected in 57.9% (11/19) of our cases. Interestingly, methylation of RASSF1A was found in 72.7% (8/11) of the cases with LOH but only in 12.5% (1/8) of the cases without LOH. Methylation of RASSF1A was detected in 50% (7/14) of voided urine samples, but not in normal control. It showed a higher sensitivity than conventional urine cytology in detecting cancer cells, especially for low grade cases. In conclusion, our results demonstrated a high frequency of RASSF1A methylation with frequent LOH in 3p21.3 region in bladder cancer. It suggested that it may be a potential tumor suppressor gene in this chromosomal region and can be silenced by promoter hypermethylation. Detection of aberrant gene methylation in routine voided urine was feasible and may provide a non‐invasive and sensitive approach for cancer detection.

Podocyte injury induced by mesangial-derived cytokines in IgA nephropathy

BACKGROUND We have previously documented that human mesangial cell (HMC)-derived tumour necrosis factor-alpha (TNF-alpha) is an important mediator involved in the glomerulo-tubular communication in the development of interstitial damage in IgA nephropathy (IgAN). With the strategic position of podocytes, we further examined the function of podocytes in IgAN. METHODS Podocyte markers were examined in renal tissues by immunofluorescence. In vitro experiments were conducted with podocytes cultured with polymeric IgA (pIgA) or conditioned medium prepared from HMC incubated with pIgA (IgA-HMC conditioned medium). RESULTS Glomerular immunostaining for nephrin or ezrin was significantly weaker in patients with IgAN. The immunostaining of IgA and nephrin was distinctly separate with no co-localization. In vitro experiments revealed no effect of pIgA on the expression of these podocyte proteins as IgA from IgAN patients did not bind to podocytes. In contrast, IgA conditioned medium prepared from IgAN patients down-regulated the expression of these podocyte proteins as well as other podocyte markers (podocin and synaptopodin) in cultured podocytes. The mRNA expression of nephrin, erzin, podocin but not synaptopodin correlated with the degree of proteinuria and creatinine clearance. The down-regulation was reproducible in podocytes cultured with TNF-alpha or transforming growth factor-beta (TGF-beta) at concentration comparable to that in the IgA-HMC conditioned medium. The expression of these podocyte proteins was restored partially with a neutralizing antibody against TNF-alpha or TGF-beta and fully with combination of both antibodies. CONCLUSION Our finding suggests podocyte markers are reduced in IgAN. An in vitro study implicates that humoral factors (predominantly TNF-alpha and TGF-beta) released from mesangial cells are likely to alter the glomerular permeability in the event of proteinuria and tubulointerstitial injury in IgAN.

Role for macrophage migration inhibitory factor in acute respiratory distress syndrome

The critical role of macrophage migration inhibitory factor (MIF) in mediating inflammatory lung injury in acute respiratory distress syndrome (ARDS) has been raised recently. The present study has identified enhanced MIF protein expression in alveolar capillary endothelium and infiltrating macrophages in lung tissues from ARDS patients. The possibility that MIF up‐regulates its synthesis in an autocrine fashion in ARDS was tested using cultured endothelial cells stimulated with MIF and a murine model of lipopolysaccharide (LPS)‐induced acute lung injury. MIF induced significant MIF and tumour necrosis factor (TNF)‐α synthesis in cultured endothelial cells and the effect was blocked by neutralizing anti‐MIF antibody. A similar blocking effect was observed when MIF‐stimulated endothelial cells were pretreated with neutralizing anti‐TNF‐α antibody or glucocorticoid, supporting the notion that MIF induced TNF‐α production via an amplifying pro‐inflammatory loop. Treatment with anti‐MIF or glucocorticoid effectively attenuated pulmonary pathology and the synthesis of MIF or TNF‐α in mice with LPS‐induced acute lung injury. Mildly augmented expression of aquaporin 1 (AQP1) was also detected in alveolar capillary endothelium in ARDS. In vitro studies revealed that both MIF and TNF‐α induced a small increase of AQP1 synthesis in cultured endothelial cells. These findings suggest that MIF plays a crucial pathological role leading to alveolar inflammation in ARDS. Anti‐MIF and early glucocorticoid therapy may represent a novel therapeutic approach for reducing alveolar inflammation in ARDS. Copyright

Intrarenal expression of miRNAs in patients with hypertensive nephrosclerosis.

BACKGROUND MicroRNAs (miRNAs) are non-coding, single-stranded RNA molecules that play important roles in a number of physiological and pathological processes. Previous studies showed that miRNAs targeting transcription factors ZEB1 and ZEB2 may repress epithelial-mesenchymal transition (EMT). METHODS We studied 34 consecutive patients with biopsy-proven hypertensive nephrosclerosis. Intrarenal expression of miR-200 family, miR-205, and miR-192 were determined. We also studied normal renal tissue from 20 patients with nephrectomy for kidney cancer as controls. RESULTS The level of intrarenal of miR-200a, miR-200b, miR-141, miR-429, miR-205, and miR-192 were significantly higher in patients with hypertensive nephrosclerosis than controls. Proteinuria correlated with intrarenal expression of miR-200a (r = 0.594, P < 0.001), miR-200b (r = 0.395, P = 0.004), miR-141 (r = 0.377, P = 0.007), miR-429 (r = 0.346, P = 0.013), miR-205 (r = 0.636, P < 0.001), and miR-192 (r = 0.306, P = 0.029). Estimated glomerular filtration rate (GFR) correlated with intrarenal expression of miR-200a (r = -0.374, P = 0.007) and miR-205 (r = -0.400, P = 0.005). Intrarenal expression of ZEB1 inversely correlated with intrarenal expression of miR-429, whereas expression of ZEB2 inversely correlated with miR-200a, miR-200b, and miR-429. CONCLUSIONS The results show that intrarenal expression of miR-200a, miR-200b, miR-141, miR-429, miR-205, and miR-192 were increased in hypertensive nephrosclerosis, and the degree of upregulation correlated with disease severity. The results suggested that these miRNA species may play important roles in the pathogenesis of hypertensive nephrosclerosis.

Urinary miR-21, miR-29, and miR-93: Novel Biomarkers of Fibrosis

Background: MicroRNAs (miRNAs) play important roles in the progression of renal fibrosis. We studied the urinary levels of miR-21, miR-29 family and miR-93, which are downstream mediators of the transforming growth factor-β1 (TGF-β1), in patients with immunoglobulin A (IgA) nephropathy. Methods: We studied the urinary miRNA levels of 43 IgA nephropathy patients and 13 healthy controls. Results: The IgA nephropathy group had significantly lower urinary miR-29b and miR-29c, but higher miR-93 levels than controls. Proteinuria significantly correlated with urinary levels of miR-29b (r = –0.388, p = 0.003) and miR-29c (r = –0.409, p = 0.002). Glomerular filtration rate significantly correlated with urinary levels of miR-21 (r = 0.338, p = 0.028), miR-29b (r = 0.333, p = 0.031) and miR-29c (r = 0.304, p = 0.050). Urinary miR-93 level significantly correlated with glomerular scarring (r = –0.392, p = 0.010). Urinary miRNA level of SMAD3, but not TGF-β1, correlated with urinary miR-21 (r = 0.624, p < 0.001), miR-29b (r = 0.566, p < 0.001), miR-29c (r = 0.619, p < 0.001) and miR-93 (r = 0.332, p = 0.032). Conclusions: Urinary miR-29b and miR-29c levels correlated with proteinuria and renal function, while urinary miR-93 level correlated with glomerular scarring. More importantly, urinary levels of these miRNA targets significantly correlated with urinary SMAD3 level. Our results suggest that these miRNA targets are regulated by the TGF-β1/SMAD3 pathway and they may play important roles in the development of progressive renal fibrosis in IgA nephropathy.