Novel treatment strategies for chronic kidney disease: insights from the animal kingdom

Many of the >2 million animal species that inhabit Earth have developed survival mechanisms that aid in the prevention of obesity, kidney disease, starvation, dehydration and vascular ageing; however, some animals remain susceptible to these complications. Domestic and captive wild felids, for example, show susceptibility to chronic kidney disease (CKD), potentially linked to the high protein intake of these animals. By contrast, naked mole rats are a model of longevity and are protected from extreme environmental conditions through mechanisms that provide resistance to oxidative stress. Biomimetic studies suggest that the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) offers protection in extreme environmental conditions and promotes longevity in the animal kingdom. Similarly, during months of fasting, immobilization and anuria, hibernating bears are protected from muscle wasting, azotaemia, thrombotic complications, organ damage and osteoporosis - features that are often associated with CKD. Improved understanding of the susceptibility and protective mechanisms of these animals and others could provide insights into novel strategies to prevent and treat several human diseases, such as CKD and ageing-associated complications. An integrated collaboration between nephrologists and experts from other fields, such as veterinarians, zoologists, biologists, anthropologists and ecologists, could introduce a novel approach for improving human health and help nephrologists to find novel treatment strategies for CKD

Proteomic characterisation of chronic lymphocytic leukaemia cells treated with rituximab

The mechanisms by which tumor cells are killed by rituximab remain unclear. An understanding of these mechanisms would improve the efficacy of rituximab therapy in B-CLL, and may lead to optimization of monoclonal antibody therapy for other diseases. To identify the signalling pathways affected by rituximab, differentially abundant cellular proteins (± rituximab) were identified from lipid rafts, the cell surface and total cell lysates of MEC1 cells. Three different methods have been used to identify proteins from the LRs proteome from the human CLL cell line, MEC1. In total, 643 proteins were found in LRs of CLL cells (580 from the sucrose gradient method, 181 depleted by MCD and 199 isolated by immuno-precipitation), 64 proteins were identified by all 3 methods. This comprehensive list of LRs proteins, includes 30 proteins with no previous association to the LRs. These proteins have roles in cell migration, adhesion, signalling pathways, apoptosis, transcription regulation, protein synthesis and degradation in cancer cells. Rituximab up-regulates GNAS, GNAI3, AKAP and the spectrins (SPTAN1 and SPTBN1) in LRs and activates Syk resulting in phosphorylation and activation of RAC1. This may have resulted in the accumulation and polymerization of actin in LRs with initiation of signaling pathways by activation of NF-kB and STAT3. That may result in activation of anti-apoptotic proteins such as c-Myc, CCND1 and Bcl2. In addition, activation of Syk activates PI3K, which induces the expression of STAT3, p-STAT3, YY1 and may induce BcL2, c-Myc, CCND1 and NF-κB and may inhibit expression of PAX5, resulting in cell proliferation. On the other hand, activation of TRIM21 by rituximab may have an essential role in turning off NF-κB signaling and STAT3 transcription that would result in Bcl2 inhibition or down-regulation, subsequently decreasing cellular resistance to apoptosis

SALUBRIOUS EFFECT OF ROTTLERIN ON HYPEROXALURIA INDUCED OXIDATIVE DAMAGE IN RATS

Objective: To investigate the in vitro oxidant scavenging properties of rottlerin and to study the potential role of rottlerin on ethylene glycol induced nephrocalcinosis in rats.Methods: In vitro oxidant scavenging properties of rottlerin were studied along with its effect on in vitro calcium phosphate mineralization. For the in vivo studies, hyperoxaluria was induced by administering 0.4 % ethylene glycol and 1 % ammonium chloride in drinking water to male wistar rats for 9 d. Rottlerin was administered intraperitoneally at 1mg/kg/d along with the hyperoxaluric agent. Total thiols content, activities of glutathione-S-transferase (GST), glutathione reductase (GR), Citrate synthase (CS), isocitrate dehydrogenase (ICDH), ATPase and urinary parameters were studied.Results: Rottlerin showed in vitro DPPH, superoxide, and ABTS radical scavenging activity along with inhibition of calcium phosphate mineralization in an in vitro homogeneous system. The diminished activities of GST, GR, ICDH, CS, ATPase and level of total thiols were considerably stabilized by rottlerin, suggesting that rottlerin provides protection against oxalate induced oxidative damage.Conclusion: We suggest that rottlerin protects the integrity of the renal cell by stabilizing the free-radical mediated damage. Thus, the present study reveals that the antioxidant nature of rottlerin protects the renal cells against oxalate-induced injury and thus, rottlerin may prevent against hyperoxaluria induced oxidative damage.Keywords: Rottlerin, Hyperoxaluria, Oxidative stress, Antioxidan

Calcium homeostasis in the central nervous system: adaptation to neurodegeneration

En aquest article, després d'una revisió dels nostres coneixements bàsics sobre moviments del alci neuronal, s'ha resentat el treball fet pel nostre grup durant els últims anys sobre neurodegeneració, juntament amb les dades obtingudes en models animals i humans en l'estudi de la precipitació cerebral del calci. Per tal d'explicar la precipitació del calci s'ha presentat i discutit un model que integra els diversos mecanismes implicats en neurodegeneració des del punt de vista de la rellevància funcional.Here we review the results of our recent studies on neurodegeneration together with data on cerebral calcium precipitation in animal models and humans. A model that integrates the diversity of mechanisms involved in neurodegeneration is presented and discussed based on the functional relevance of calcium precipitation

Application of the Pyroantimonate Method and Electron Probe Microanalysis to the Study of Glycogen Metabolism in Liver

Glycogen distribution in the liver of mouse under different metabolic conditions was studied by the pyroantimonate (PA) method combined with semi-quantitative electron probe microanalysis (EPMA). In the liver of animals subjected to a sugar-rich diet, glycogen granules were abundant and electron transparent. In fasted animals, they were less numerous and stained by PA, which indicates the presence of a complexed cation. This cation was identified as calcium by EPMA. In both cases, adjacent cytoplasmic areas contained masked calcium not revealed by PA but detected by EPMA, which is characteristic of a neutral complexed form; but in the case of the fasted animals, the calcium concentration was significantly lower. If the liver of fasted animals was dissected in 0.2% glucose-containing medium, the glycogen areas dramatically released calcium and lost their stainability by PA, whereas mitochondria and adjacent cytoplasm contained many PA precipitates rich in calcium and sodium, suggesting a sudden increase of intracellular [Ca2+]. In mitochondria, the sodium:calcium ratio was relatively constant, which suggests a process involving a coupling between these two elements. Our results could be explained in the light of physiological and biochemical data. We particularly noted that diffusible cations as calcium and sodium did not appear to be displaced over long distances from their likely source. This observation agrees with recent theories on the state of water and ion mobility in the cell

The Effects of Leucine and Dairy Products on Adipose Tissue Inflammation: The Role of Adipocyte Derived Microvesicles

Obesity is characterized by chronic oxidative and inflammatory stress, and adipose tissue is a significant source of inflammatory cytokines. Previous studies demonstrated that dairy products (rich in calcium and leucine) can alleviate obesity-associated inflammatory stress through suppression of 1, 25-dihydroxycholecalciferol (calcitriol) with calcium and the high leucine content in dairy. We have also shown leucine treatment increases anti-inflammatory adiponectin expression and decreases pro-inflammatory cytokines TNF-a [alpha], MCP-1, and IL-6 expression in adipocytes. Therefore, we sought to determine if these alterations in inflammatory cytokine production could have a functional effect on the inflammatory process, specifically monocyte – endothelial cell adhesion as this is one of the initial events of the inflammatory process. We demonstrate that leucine treatment of adipocytes reduces monocyte CD11b expression, endothelial cell ICAM-1 expression and, consequently, monocyte – endothelial cell adhesion in vitro while calcitriol exerted the opposite effects. Furthermore, plasma samples from obese individuals consuming high dairy diets (\u3e [greater than] 3.5 servings/day) over a 12-week period reduced monocyte – endothelial cell adhesion, ex vivo. Recently, adipocyte derived microvesicles (ADMs) have been suggested to play a role in communication between adipose tissue and systemic circulation, so we sought to determine if adiponectin present on ADMs was responsible for the anti-inflammatory effects we have observed when treating adipocytes with leucine. Therefore, after adipocytes were treated for 48 hrs with leucine, the whole conditioned media (CM), purified ADMs, and remaining supernatant were applied to human peripheral blood to measure monocyte CD11b expression. Compared to control, leucine CM and the isolated ADMs both reduced monocyte CD11b expression while the supernatant fraction did not. Knocking down adiponectin with siRNA attenuated these effects, suggesting adiponectin associated with ADMs plays a role in mediating the anti-inflammatory effects we have observed. Collectively, these data suggest that dairy products can provide beneficial effects at reducing obesity-associated inflammation, and ADMs, in part, mediate some of these effects

The energy sensor AMPK regulates Hedgehog signaling in human cells through a unique Gli1 metabolic checkpoint

Hedgehog signaling controls proliferation of cerebellar granule cell precursors (GCPs) and its aberrant activation is a leading cause of Medulloblastoma, the most frequent pediatric brain tumor. We show here that the energy sensor AMPK inhibits Hh signaling by phosphorylating a single residue of human Gli1 that is not conserved in other species.Studies with selective agonists and genetic deletion have revealed that AMPK activation inhibits canonical Hh signaling in human, but not in mouse cells. Indeed we show that AMPK phosphorylates Gli1 at the unique residue Ser408, which is conserved only in primates but not in other species. Once phosphorylated, Gli1 is targeted for proteasomal degradation. Notably, we show that selective AMPK activation inhibits Gli1-driven proliferation and that this effect is linked to Ser408 phosphorylation, which represents a key metabolic checkpoint for Hh signaling.Collectively, this data unveil a novel mechanism of inhibition of Gli1 function, which is exclusive for human cells and may be exploited for the treatment of Medulloblastoma or other Gli1 driven tumors