Is there long-term value of pathology scoring in immunoglobulin A nephropathy? A validation study of the Oxford Classification for IgA Nephropathy (VALIGA) update.

BACKGROUND: It is unknown whether renal pathology lesions in immunoglobulin A nephropathy (IgAN) correlate with renal outcomes over decades of follow-up. METHODS: In 1130 patients of the original Validation Study of the Oxford Classification for IgA Nephropathy (VALIGA) cohort, we studied the relationship between the MEST score (mesangial hypercellularity, M; endocapillary hypercellularity, E; segmental glomerulosclerosis, S; tubular atrophy/interstitial fibrosis, T), crescents (C) and other histological lesions with both a combined renal endpoint [50% estimated glomerular filtration rate (eGFR) loss or kidney failure] and the rate of eGFR decline over a follow-up period extending to 35 years [median 7 years (interquartile range 4.1-10.8)]. RESULTS: In this extended analysis, M1, S1 and T1-T2 lesions as well as the whole MEST score were independently related with the combined endpoint (P < 0.01), and there was no effect modification by age for these associations, suggesting that they may be valid in children and in adults as well. Only T lesions were associated with the rate of eGFR loss in the whole cohort, whereas C showed this association only in patients not treated with immunosuppression. In separate prognostic analyses, the whole set of pathology lesions provided a gain in discrimination power over the clinical variables alone, which was similar at 5 years (+2.0%) and for the whole follow-up (+1.8%). A similar benefit was observed for risk reclassification analyses (+2.7% and +2.4%). CONCLUSION: Long-term follow-up analyses of the VALIGA cohort showed that the independent relationship between kidney biopsy findings and the risk of progression towards kidney failure in IgAN remains unchanged across all age groups and decades after the renal biopsy.

Risk factors for progression in children and young adults with IgA nephropathy: an analysis of 261 cases from the VALIGA European cohort.

BACKGROUND: There is a need for early identification of children with immunoglobulin A nephropathy (IgAN) at risk of progression of kidney disease. METHODS: Data on 261 young patients [age <23 years; mean follow-up of 4.9 (range 2.5-8.1) years] enrolled in VALIGA, a study designed to validate the Oxford Classification of IgAN, were assessed. Renal biopsies were scored for the presence of mesangial hypercellularity (M1), endocapillary hypercellularity (E1), segmental glomerulosclerosis (S1), tubular atrophy/interstitial fibrosis (T1-2) (MEST score) and crescents (C1). Progression was assessed as end stage renal disease and/or a 50 % loss of estimated glomerular filtration rate (eGFR) (combined endpoint) as well as the rate of renal function decline (slope of eGFR). Cox regression and tree classification binary models were used and compared. RESULTS: In this cohort of 261 subjects aged <23 years, Cox analysis validated the MEST M, S and T scores for predicting survival to the combined endpoint but failed to prove that these scores had predictive value in the sub-group of 174 children aged <18 years. The regression tree classification indicated that patients with M1 were at risk of developing higher time-averaged proteinuria (p < 0.0001) and the combined endpoint (p < 0.001). An initial proteinuria of ≥0.4 g/day/1.73 m2 and an eGFR of <90 ml/min/1.73 m2 were determined to be risk factors in subjects with M0. Children aged <16 years with M0 and well-preserved eGFR (>90 ml/min/1.73 m2) at presentation had a significantly high probability of proteinuria remission during follow-up and a higher remission rate following treatment with corticosteroid and/or immunosuppressive therapy. CONCLUSION: This new statistical approach has identified clinical and histological risk factors associated with outcome in children and young adults with IgAN.

[The management in surgery of the polycystic disease]. / Gestione in ambulatorio della malattia policistica.

The polycystic kidney disease is a genetic disease, therefore clinical features are not referred just to the affected person, but also to the other members of the family. On the other hand, the disease causes systemic involvement and it requires the contribution of different specialists such as nephrologist, geneticist, radiologist and others. Therefore, the establishment of outpatient clinics, in which a multidisciplinary team assesses the clinical features of patients belonging to the same family, is recommended.

The role of tonsillectomy in IgA nephropathy.

The IgA nephropathy (IgAN) is a very common glomerulonephritis and can result in end-stage renal disease. From a clinical point of view, IgAN is characterised by repeated events of macrohaematuria associated with infections of the upper airways. In IgAN, the IgA released by the tonsillar lymphatic tissue into blood circulation are defective in glycosylation. These aberrant IgA can reach the glomeruli and deposit into mesangium causing an inflammation with cellular proliferation. The treatment is not yet well defined: steroids and immunosuppressive drugs are suggested in cases with a progressive disease. Tonsillectomy was proposed to reduce the infective events of upper airways and the lymphatic tissue producing undergalactosylated IgA. The experiences in literature coming from Asia report positive effects of tonsillectomy on IgAN. In patients with tonsillectomy, the renal signs improved (less haematuria and proteinuria) and the renal outcome was better (slower progression of renal damage). These were uncontrolled studies and tonsillectomy was associated with steroid and immunosuppressive treatment, so it is not possible to tell the real effect of tonsillectomy. In contrast, the European studies reported that the tonsillectomy was not associated with a better outcome of IgAN. A critical review of the subject reveals that most of the papers with positive results were uncontrolled retrospective experiences, while in a randomised controlled trial paper the advantages of tonsillectomy disappeared. In conclusion, this review, in agreement with the international guidelines, concludes that tonsillectomy does not play any role in the progression of IgAN.

Extracapillary proliferation is an independent predictive factor in Immunoglobulin A nephropathy.

BACKGROUND: Oxford classification of Immunoglobulin A Nephropathy (IgAN) identifies four pathological features as predictors of renal outcome (MEST-score): mesangial proliferation (M); endocapillary proliferation (E); segmental glomerulosclerosis (S); tubular atrophy/interstitial fibrosis (T). In particular extracapillary proliferation (Ex) was not considered as an independent histological variable predicting renal outcome. Recently the VALIGA study provided a validation of the Oxford classification in a large European cohort of IgAN patients and re-stated that Ex is not associated with a worse renal prognosis. We propose a retrospective study to evaluate the predictive value of the MEST-score in a multi-centre, single region group of patients from central Italy and in addition, to investigate Ex as a marker predicting renal outcome. METHODS: One hundred and seven patients were enrolled in this study. Clinical data of each patient were available at diagnosis and follow-up. The median age at diagnosis was 36.7 years; 72% of the patients were males. Histological parameters were those included in the MEST-score of the Oxford classification; in addition, Ex was also assessed. RESULTS: Multiple linear regression models for survey were used. Statistical analysis showed a correlation between the progression of renal decline, in terms of estimated glomerular filtration rate (slope eGFR), and M, S, T. Differently from Oxford and VALIGA studies, no correlation was found with E, while Ex correlated with a decline of eGFR. CONCLUSIONS: Our results suggest that Ex represents an additional independent variable associated with a faster decline of renal function in IgAN.

Discovery of new risk loci for IgA nephropathy implicates genes involved in immunity against intestinal pathogens.

We performed a genome-wide association study (GWAS) of IgA nephropathy (IgAN), the most common form of glomerulonephritis, with discovery and follow-up in 20,612 individuals of European and East Asian ancestry. We identified six new genome-wide significant associations, four in ITGAM-ITGAX, VAV3 and CARD9 and two new independent signals at HLA-DQB1 and DEFA. We replicated the nine previously reported signals, including known SNPs in the HLA-DQB1 and DEFA loci. The cumulative burden of risk alleles is strongly associated with age at disease onset. Most loci are either directly associated with risk of inflammatory bowel disease (IBD) or maintenance of the intestinal epithelial barrier and response to mucosal pathogens. The geospatial distribution of risk alleles is highly suggestive of multi-locus adaptation, and genetic risk correlates strongly with variation in local pathogens, particularly helminth diversity, suggesting a possible role for host-intestinal pathogen interactions in shaping the genetic landscape of IgAN.

Increased Nek1 expression in renal cell carcinoma cells is associated with decreased sensitivity to DNA-damaging treatment.

Renal cell carcinoma (RCC) is a heterogeneous disease with resistance to systemic chemotherapy. Elevated expression of multiple drug resistance (MDR) has been suggested to be one of the mechanisms for this resistance. Here, we provide an alternative mechanism to explain RCC's resistance to chemotherapy-induced apoptosis. Never-in mitosis A-related protein kinase 1 (Nek1) plays an important role in DNA damage response and proper checkpoint activation. The association of Nek1 with the voltage-dependent anion channel (VDAC1) is a critical determinant of cell survival following DNA-damaging treatment. We report here that Nek1 is highly expressed in RCC tumor and cultured RCC cells compared to that of normal renal tubular epithelial cells (RTE). The association between Nek1 and VDAC1 is genotoxic dependent: prolonged Nek1/VDAC1 dissociation will lead to VDAC1 dephosphorylation and initiate apoptosis. Down-regulation of Nek1 expression in RCC cells enhanced their sensitivity to DNA-damaging treatment. Collectively, these results suggest that the increased Nek1 expression in RCC cells maintain persistent VDAC1 phosphorylation, closing its channel and preventing the onset of apoptosis under genotoxic insults. Based on these results, we believe that Nek1 can serve as a potential therapeutic target for drug development in the treatment of RCC.

Granulomatous interstitial nephritis in a patient with Crohn's disease.

A case of granulomatous interstitial nephritis (GIN) associated with Crohn's disease (CD) was reported. GIN is a rare pathological finding in renal biopsy specimens. In a patient affected by CD, granulomas may be found in various tissues and organs such as lymph nodes, mesentery, liver, and lungs and occasionally in bones, joints, and skeletal muscle. Few cases of granuloma have been reported in the kidney, and it is not always possible to relate the presence of granuloma to CD, to other interstitial granulomatosis diseases, or to a drug-induced reaction. The issue has a remarkable clinical effect; indeed, the answer requires a completely different therapeutic approach. The diagnosis analysis on the basis of clinical-pathological evidences and on reports from literature is discussed.

[Immunotherapy mechanisms in glomerulonephritis]. / Meccanismi della terapia immunologica nelle glomerulonefriti.

The pathogenetic mechanisms of glomerulonephritis are numerous and complex, involving both humoral and cell-mediated immune responses. The ability of drugs to interfere with immune pathways has not been completely understood and the treatment of glomerulonephritis is therefore still empirical and based on clinical studies. Corticosteroids are the most commonly used drugs; their mechanism of action is variable and can be modulated by the prescribed dosage. Immunosuppressive drugs employed for the treatment of glomerulonephritis include alkylating agents such as cyclophosphamide and antimetabolites such as mycophenolate-mofetil and azathioprine. These drugs have a powerful immunosuppressive effect but are associated with several dangerous side effects. Cyclosporin A is a calcineurin inhibitor belonging to the class of immunomodulators and is able to interfere with the immune response. Another group of drugs are monoclonal antibodies, the most popular among which is rituximab. It is an antibody directed against the transmembrane protein CD20, specifically espressed on the surface of B lymphocytes. Its use is limited to cases in which the usual therapy with steroids and immunosuppressive drugs was ineffective. The clinical studies conducted so far look promising.

Mutation of NIMA-related kinase 1 (NEK1) leads to chromosome instability.

BACKGROUND: NEK1, the first mammalian ortholog of the fungal protein kinase never-in-mitosis A (NIMA), is involved early in the DNA damage sensing/repair pathway. A defect in DNA repair in NEK1-deficient cells is suggested by persistence of DNA double strand breaks after low dose ionizing radiation (IR). NEK1-deficient cells also fail to activate the checkpoint kinases CHK1 and CHK2, and fail to arrest properly at G1/S or G2/M-phase checkpoints after DNA damage. RESULTS: We show here that NEK1-deficient cells suffer major errors in mitotic chromosome segregation and cytokinesis, and become aneuploid. These NEK1-deficient cells transform, acquire the ability to grow in anchorage-independent conditions, and form tumors when injected into syngeneic mice. Genomic instability is also manifest in NEK1 +/- mice, which late in life develop lymphomas with a much higher incidence than wild type littermates. CONCLUSION: NEK1 is required for the maintenance of genome stability by acting at multiple junctures, including control of chromosome stability.

Phosphorylation by Nek1 regulates opening and closing of voltage dependent anion channel 1.

VDAC1 is a key component of the mitochondrial permeability transition pore. To initiate apoptosis and certain other forms of cell death, mitochondria become permeable such that cytochrome c and other pre-apoptotic molecules resident inside the mitochondria enter the cytosol and activate apoptotic cascades. We have shown recently that VDAC1 interacts directly with never-in-mitosis A related kinase 1 (Nek1), and that Nek1 phosphorylates VDAC1 on Ser193 to prevent excessive cell death after injury. How this phosphorylation regulates the activity of VDAC1, however, has not yet been reported. Here, we use atomic force microscopy (AFM) and cytochrome c conductance studies to examine the configuration of VDAC1 before and after phosphorylation by Nek1. Wild-type VDAC1 assumes an open configuration, but closes and prevents cytochrome c efflux when phosphorylated by Nek1. A VDAC1-Ser193Ala mutant, which cannot be phosphorylated by Nek1 under identical conditions, remains open and constitutively allows cytochrome c efflux. Conversely, a VDAC1-Ser193Glu mutant, which mimics constitutive phosphorylation by Nek1, remains closed by AFM and prevents cytochrome c leakage in the same liposome assays. Our data provide a mechanism to explain how Nek1 regulates cell death by affecting the opening and closing of VDAC1.

NIMA-related protein kinase 1 is involved early in the ionizing radiation-induced DNA damage response.

Cellular functions of the NimA-related mammalian kinase Nek1 have not been demonstrated to date. Here we show that Nek1 is involved early in the DNA damage response induced by ionizing radiation (IR) and that Nek1 is important for cells to repair and recover from DNA damage. When primary or transformed cells are exposed to IR, Nek1 kinase activity is increased within 4 minutes, and Nek1 expression is up-regulated shortly thereafter and sustained for hours. At the same early time frame after IR that its kinase activity is highest, a portion of Nek1 redistributes in cells from cytoplasm to discrete nuclear foci at sites of DNA double-strand breaks. There it colocalizes with gamma-H2AX and NFBD1/MDC1, two key proteins involved very early in the response to IR-induced DNA double-strand breaks. Finally, Nek1-deficient fibroblasts are much more sensitive to the effects of IR-induced DNA damage than otherwise identical fibroblasts expressing Nek1. These results suggest that Nek1 may function as a kinase early in the DNA damage response pathway.

Mechanisms of repair after kidney injury.

Kidney injury is repaired by inflammatory and non-inflammatory mechanisms, with the extent of recovery based on severity of the insult. Critical to the assessment of kidney repair is the ability to differentiate functional recovery from structural repair: compensatory increases in the function of intact residual nephrons often mask the inability of the kidney to heal or replace damaged structures. The mechanisms of repair reflect three levels of injury, which are handled differently by the kidney. First, DNA damage is countered by proof-reading DNA polymerases, backed by other controls for sequence misalignment/nucleotide replacement. If DNA cannot be repaired, cells harboring mutation(s) are lost through apoptosis, which is also critical to the disposal of kidney cells and infiltrating leukocytes in both acute and chronic ischemic, immunological, or chemical damage. This leaves room for a second mechanism of repair, i.e., cellular proliferation. At least 5 types of reparative proliferation are known to occur, some of which involve stem cell differentiation and perhaps immigration from distant reservoirs. The final type of repair is referred to as structural repair, actually quite limited by lack of postnatal nephrogenesis in the human kidney. Certain forms of recovery after acute tubular necrosis involve extensive remodeling of the proximal tubule, where integrity of the basement membrane is required for successful repair. Contrary to the long-held belief that only acute injury can be repaired, while ongoing chronic damage leads to progressive nephron loss, evidence is emerging that some degree of renal remodeling occurs even in the presence of persistent structural changes.

Transmembrane signalling in human monocyte/mesangial cell co-cultures: role of cytosolic Ca(2+).

BACKGROUND: Adhesion of monocytes triggers apoptosis, cytotoxicity, cytokine release, and later proliferation of cultured human mesangial cells (HMC). In the search for transmembrane signals transducing the interaction of HMC adhesion molecules with leukocyte counterreceptors, we measured variations of cytosolic Ca(2+) ([Ca(2+)](i)) in HMC and monocytes of the U937 cell line during 6-h co-cultures. METHODS: Monolayer cultures of HMC and suspensions of U937 cells were loaded with the fluoroprobe fura 2-AM and subsequently co-cultured for 6 h while separately monitoring by microfluorometry the Ca(2+)-dependent 500 nm fluorescent emission of each cell line at fixed intervals upon excitation at 340/380 nm. RESULTS: U937 and peripheral blood monocyte adhesion was followed in HMC by a slow, progressive rise of [Ca(2+)](i) from basal levels of 96+/-9 nM to 339+/-54 at 60 min and 439+/-44 nM at 3 h. The [Ca(2+)](i) elevation reached a steady state thereafter, while parallel monolayers incubated with control media maintained resting levels throughout the co-culture with stable fluoroprobe retention. Receptor sensitivity to vasoconstrictor agents, including compounds not released by monocytes, such as angiotensin II, was rapidly downregulated in HMC co-cultured with U937 cells. No [Ca(2+)](i) changes could be elicited by the octapeptide or by the TxA(2) analogue, U-46619, as early as 30 min after exposure to U937 cells. No [Ca(2+)](i) changes were observed in U937 cells throughout the co-culture. Conditioned media from monocytes and from co-cultured HMC+U937 cells had no effect on [Ca(2+)](i) of HMC. Ca(2+) entry leading to fura 2 saturation was still inducible by Ca(2+) ionophores, such as ionomycin and 4-Br-A23187, which also inhibited the responses to vasoconstrictors. Ca(2+)-free solutions prevented the [Ca(2+)](i) rise as well as subsequent receptor inactivation, implicating Ca(2+) influx through store-operated Ca(2+) channels (SOC), a major pathway for Ca(2+) entry in these cultured cells. Ca(2+) influx was confirmed by Mn(2+)-quenching of fura 2. CONCLUSIONS: In HMC, early changes in [Ca(2+)](i) signal for monocyte adhesion in a co-culture model of glomerular inflammation. This signalling mechanism may mediate the functional responses elicited in glomerular cells by leukocytes, including downregulation of receptors for vasoactive agents.