Acute and chronic glomerular damage is associated with reduced CD133 expression in urinary extracellular vesicles.

Extracellular vesicles released into urine (uEVs) can represent interesting biomarkers of renal cell damage. CD133, a stem/progenitor cell marker expressed by renal progenitor cells, is highly expressed in uEVs of healthy individuals. In the present study, we evaluated the level of CD133 in the uEVs of patients with acute and chronic glomerular damage by cytofluorimetric analysis. The level of CD133+ uEVs was significantly decreased in pediatric patients with acute glomerulonephritis during the acute phase of renal damage, while it was restored after the subsequent recovery. A similar decrease was also observed in patients with chronic glomerulonephritis. Moreover, CD133+ uEVs significantly declined in patients with type 2 diabetes, used as validation group, with the lowest levels in patients with albuminuria with diabetic nephropathy. Indeed, receiver-operating characteristic curve analysis indicates the ability of CD133+ uEV values to discriminate the health condition from that of glomerular disease. In parallel, a significant decrease of CD133 in renal progenitor cells and in their derived EVs was observed in vitro after cell treatment with a combination of glucose and albumin overload, mimicking the diabetic condition. These data indicate that the level of CD133+ uEVs may represent an easily accessible marker of renal normal physiology and could provide information on the "reservoir" of regenerating cells within tubules.

Assessment of acute kidney injury in rhabdomyolytic mice by transcutaneous measurement of sinistrin excretion.

BACKGROUND: Early and accurate assessment of renal function is required for the successful detection and treatment of acute kidney injury (AKI). However, only retention parameters such as plasma urea and creatinine, and the indirect estimation of glomerular filtration rate are commonly available. METHODS: Here, we measured the kinetics of plasma fluorescein isothiocyanate (FITC)-sinistrin excretion to detect alterations of renal function over time in a murine model of rhabdomyolysis-induced AKI. The half-life of FITC-sinistrin was evaluated using a transcutaneous device at different time points in conscious mice, from 4 days before renal damage up to 30 days after. Retention markers were also evaluated, in parallel. RESULTS: Evaluation of the FITC-sinistrin half-life revealed early reduction of renal filtration, observed as early as 6 h after renal damage, and maintained up to 12 h following AKI. Plasma creatinine and urea levels correlated with the transcutaneous measurements of sinistrin excretion. Evaluation of sinistrin excretion also demonstrated that glycerol-treated animals did not develop AKI. Finally, histological analysis showed the presence of renal parenchymal lesions, which developed following the reduced renal filtration and persisted over time, highlighting the causative role of vascular dysfunction and myoglobin toxicity on the subsequent induction of tissue damage. CONCLUSIONS: Taken together, the results of this study provide important insights into the pathophysiology of kidney injury in rhabdomyolytic mice, and indicate that the transcutaneous measurement of FITC-sinistrin is an efficient and simple method to assess renal function precisely. This method also allows reduction of the required number of experimental animals by monitoring the same mouse over time.

Toll-like receptors, immunoproteasome and regulatory T cells in children with Henoch-Schönlein purpura and primary IgA nephropathy.

BACKGROUND: Henoch-Schönlein purpura (HSP) nephritis and primary IgA nephropathy (pIgAN) present with glomerular IgA deposits, but differ with regard to clinical features. The suspected involvement of different immune system pathways is largely unknown. METHODS: This study was aimed at investigating some of the immunological features including Toll-like receptors (TLR), proteasome (PS)/immunoproteasome (iPS) switch, and the regulatory T cell system (Treg/Th17 cells) in 63 children with HSP with/without renal involvement and in 25 with pIgAN. Real-time PRC (Taqman) was used to quantify mRNA levels in peripheral blood mononuclear cells (PBMC). RESULTS: The expression of mRNAs encoding for TLR4 in both HSP and pIgAN was higher than in controls (HC) and in both diseases FoxP3mRNA and TGF-ß1mRNA expression was significantly lower than in HC. A switch from PS to iPS (LMP2/ß1) was detected only in PBMC of HSP and it correlated with the level of TLR2mRNA, which was selectively increased only in children with HSP. CONCLUSION: Children with HSP and pIgAN present with similar signs of engagement of the innate immunity and regulatory T cell depression. The increased immunoproteasome switch, which correlated with TLR2 activation, may suggest an innate immunity pathway peculiar to HSP vasculitic presentation. This research area also deserves further investigation for possible therapeutic applications.

Can tonsillectomy modify the innate and adaptive immunity pathways involved in IgA nephropathy?

The benefits of tonsillectomy in IgA nephropathy (IgAN) are still debated. Tonsillectomy may remove pathogen sources and reduce the mucosal associated lymphoid tissue (MALT), limiting degalactosylated IgA1 (deGal-IgA1) production, which is considered to be the initiating pathogenetic event leading to IgA glomerular deposition. In the European network VALIGA, 62/1147 IgAN patients underwent tonsillectomy (TxIgAN). In a cross-sectional study 15 of these patients were tested and compared to 45 non-tonsillectomized IgAN (no-TxIgAN) and healthy controls (HC) regarding levels of deGal-IgA1, and markers of innate immunity and oxidative stress, including toll-like receptors (TLR)2, 3, 4 and 9 mRNAs, proteasome (PS) and immunoproteasome (iPS) mRNAs in peripheral blood mononuclear cells (PBMC), and advanced oxidation protein products (AOPP). Levels of deGal-IgA1 were lower in TxIgAN than in no-TxIgAN (p = 0.015), but higher than in HC (p = 0.003). TLR mRNAs were more expressed in TxIgAN than in HC (TLR4, p = 0.021; TLR9, p = 0.027), and higher in TxIgAN than in no-TxIgAN (p ≤ 0.001 for TLR2, 4, 9). A switch from PS to iPS was detected in PBMC of TxIgAN in comparison to HC and it was higher than in no-TxIgAN [large multifunctional peptidase (LMP)2/ß1, p = 0.039; LPM7/ß5, p < 0.0001]. The levels of AOPP were significantly higher in TxIgAN than HC (p < 0.001) and no-TxIgAN (p = 0.033). In conclusion, the activation of innate immunity via TLRs and ubiquitin-proteasome pathways and the pro-oxidative milieu were not affected by tonsillectomy, even though the levels of aberrantly galactosylated IgA1 were lower in patients with IgAN who had tonsillectomy. The residual hyperactivation of innate immunity in tonsillectomized patients may result from extra-tonsillar MALT.