Leptin signaling impairs macrophage defenses against Salmonella Typhimurium.

The dynamic interplay between metabolism and immune responses in health and disease, by which different immune cells impact on metabolic processes, are being increasingly appreciated. However, the potential of master regulators of metabolism to control innate immunity are less understood. Here, we studied the cross-talk between leptin signaling and macrophage function in the context of bacterial infections. We found that upon infection with Gram-negative pathogens, such as Salmonella Typhimurium, leptin receptor (Lepr) expression increased in both mouse and human macrophages. Unexpectedly, both genetic Lepr ablation in macrophages and global pharmacologic leptin antagonization augmented lysosomal functions, reduced S Typhimurium burden, and diminished inflammation in vitro and in vivo. Mechanistically, we show that leptin induction activates the mTORC2/Akt pathway and subsequently down-regulates Phlpp1 phosphatase, allowing for phosphorylated Akt to impair lysosomal-mediated pathogen clearance. These data highlight a link between leptin signaling, the mTORC2/Phlpp1/Akt axis, and lysosomal activity in macrophages and have important therapeutic implications for modulating innate immunity to combat Gram-negative bacterial infections.

Non-invasive urine markers for the differentiation between RCCs and oncocytoma.

BACKGROUND: Recently, our group showed that Vim3 is overexpressed in tissue samples of renal oncocytomas and Mxi-2 in clear cell renal carcinoma (ccRCC). The mechanism leading to the truncation of both proteins is known and involves with two miRs, both detectable in urine. Since the analysis of miRs is time-consuming, our aim was to identify the truncated proteins in urine instead. Furthermore, urine samples from small renal masses (SRMs) (n = 45, <4 cm) were analyzed to get a pre-surgical differentiation of the cancer subtypes. METHODS: Urines were accessed from the urological biobank (n = 350). Proteins were isolated from urine samples, and Western blots were performed. Each sample was analyzed with ELISA for the expression of Vim3 and Mxi-2. A lateral flow assay was established. For the detection of SRMs, the miRs were isolated and qRT-PCR was performed. RESULTS: A significant increase of Vim3 in urines from patients with oncocytoma (n = 20) was detectable with ELISA compared to all other subtypes of RCCs (chromophobe (n = 50), papillary (n = 40), ccRCC (n = 200), and controls (n = 40) (***p < 0.0001)). Mxi-2 was predominantly overexpressed in ccRCCs (***p < 0.0001). Lateral flow assay of Vim3 and Mxi-2 shows two bands in the case of oncocytoma and ccRCC indicating the specificity of this test. For SRMs, an overexpression of miR-15a/Mxi2 was detectable in urine samples from ccRCC and chromoRCC patients. In contrast to that, miR-498/Vim3 were predominantly overexpressed in oncocytoma patients. CONCLUSION: Both proteins (Vim3 and Mxi-2) were detectable in patients' urines and can be used for the non-invasive differentiation of kidney cancers.

MicroRNAs as markers to monitor endothelin-1 signalling and potential treatment in renal disease: Carcinoma - proteinuric damage - toxicity.

This review highlights new developments in miRNA as diagnostic and surveillance tools in diseases damaging the renal proximal tubule mediated by endothelin in the field of renal carcinoma, proteinuric kidney disease and tubulotoxicity. A new mechanism in the miRNA regulation of proteins leads to the binding of the miRNA directly to the DNA with premature transcriptional termination and hence the formation of truncated protein isoforms (Mxi2, Vim3). These isoforms are mediated through miRNA15a or miRNA 498, respectively. ET-1 can activate a cytoplasmic complex consisting of NF-κB p65, MAPK p38α, and PKCα. Consequently, PKCα does not transmigrate into the nucleus, which leads to the loss of suppression of a primiRNA15a, maturation of this miRNA in the cytoplasm, tubular secretion and detectability in the urine. This mechanism has been shown in renal cell carcinoma and in proteinuric disease as a biomarker for the activation of the signalling pathway. Similarly, ET-1 induced miRNA 498 transmigrates into the nucleus to form the truncated protein Vim3, which is a biomarker for the benign renal cell tumour, oncocytoma. In tubulotoxicity, ET-1 induced miRNa133a down-regulating multiple-drug-resistant related protein-2, relevant for proteinuric and cisplatin/cyclosporine A toxicity. Current advantages and limitations of miRNAs as urinary biomarkers are discussed.

Sudden death of a young adult with coronary artery vasculitis, coronary aneurysms, parvovirus B19 infection and Kawasaki disease.

We present a case of a 20-year-old man who suffered from Kawasaki disease (KD) associated with a florid parvovirus infection, and who died suddenly from thrombotic occlusion of the coronary arteries. The autopsy revealed several aneurysms of the coronary arteries, a chronic vasculitis and a myofibroblast proliferation leading to focal luminal narrowing. The inflammatory response as well as the detection of the viral particles by PCR in blood and in the lesional tissue demonstrated a possible cause by Parvovirus infection. The expression of endoglin on endothelial cells of neoangiogenesis indicates the involvement of the TGF-beta pathway, necessary for maintaining chronic inflammation. In addition, a possible connection between the intake of methylphenidate, arteritis and a possible pre-existing heart disease must be discussed. Furthermore, KD must also be considered as a cause of sudden death in the adult population.

New Lineage of Lassa Virus, Togo, 2016.

We describe a strain of Lassa virus representing a putative new lineage that was isolated from a cluster of human infections with an epidemiologic link to Togo. This finding extends the known range of Lassa virus to Togo.

Exosomes as miRNA Carriers: Formation-Function-Future.

Exosomes, which are one of the smallest extracellular vesicles released from cells, have been shown to carry different nucleic acids, including microRNAs (miRNAs). miRNAs significantly regulate cell growth and metabolism by posttranscriptional inhibition of gene expression. The rapidly changing understanding of exosomes' formation and function in delivering miRNAs from cell to cell has prompted us to review current knowledge in exosomal miRNA secretion mechanisms as well as possible therapeutic applications for personalized medicine.

ET-1 Induced Downregulation of MRP2 via miRNA 133a - A Marker for Tubular Nephrotoxicity?

BACKGROUND: Multiple drug resistance (MDR), known from treating malignant tumors with chemotherapy, increases the efflux of reabsorbed reagents in tumor cells. This mechanism has been reported in the renal proximal tubule and may prevent therapeutic tubular protection in proteinuria. Since endothelin-1 (ET-1), a major component in the urine of proteinuric patients, stimulates proximal tubules, its influence on MDR was analyzed with emphasis on the multidrug resistance-associated protein 2 (MRP2), a prominent transporter in the human proximal tubule and microRNA (miRNA) 133a. METHODS: ET-1 stimulated, cultured human renal proximal tubule cells (RPTECs), were analyzed via Western blot for the expression of MRP2 and via qRT-PCR for miRNA 133a. For direct interaction between the miRNA 133a and the 3'UTR of MRP2, an immunoprecipitation was performed using FITC-labelled miRNA 133a as capture, followed by MRP2 PCR analysis and Sanger sequencing. Murine Adriamycin nephropathic model and human proteinuric samples showed high levels of miRNA 133a but low levels of MRP2. The increasing miRNA 133a levels were detectable in urine samples of humans and animals. RESULTS: ET-1 activates the miRNA 133a, which can bind to the 3'UTR of MRP2 and is therefore responsible for the detectable decrease of MRP2. CONCLUSION: This is the first report to analyze the correlation between ET-1-induced miRNA 133a overexpression in proteinuria resulting in MRP2 downregulation, which is a contributing factor for renal cytotoxicity. The detection of the miRNA 133a in urine samples can be possibly used as a monitor for cytotoxicity.

MicroRNA function in the profibrogenic interplay upon chronic liver disease.

In chronic liver disease leading to fibrosis, hepatic stellate cells (HSC) differentiate into myofibroblasts. Myofibroblastic HSC have taken center stage during liver fibrogenesis, due to their remarkable synthesis of extracellular matrix proteins, their secretion of profibrogenic mediators and their contribution to hypertension, due to elevated contractility. MicroRNAs (miRNAs) are small, noncoding RNA molecules of 19-24 nucleotides in length. By either RNA interference or inhibition of translational initiation and elongation, each miRNA is able to inhibit the gene expression of a wide panel of targeted transcripts. Recently, it was shown that altered miRNA patterns after chronic liver disease highly affect the progression of fibrosis by their potential to target the expression of extracellular matrix proteins and the synthesis of mediators of profibrogenic pathways. Here, we underline the role of miRNAs in the interplay of the profibrogenic cell communication pathways upon myofibroblastic differentiation of hepatic stellate cells in the chronically injured liver.

MicroRNA 15a, inversely correlated to PKCα, is a potential marker to differentiate between benign and malignant renal tumors in biopsy and urine samples.

NF-κB signal transduction is a potential therapeutic target in many malignant tumors. We have recently shown, in malignant renal proximal tumor cells, that a transcription complex, consisting of NF-κB p65 and mitogen-activated protein kinase p38α, joined by protein kinase C (PKC) α, transmigrates into the nucleus. There, PKCα suppresses the nuclear release of primary microRNA (pri-miRNA) 15a. Induced by endothelin (ET)-1, a decrease in PKCα levels leads to increased miRNA 15a (miR-15A) expression. An identical system can be identified in renal carcinomas, in which, after nuclear transmigration, PKCα binds directly to pri-miRNA 15a in the nucleus. However, the pattern of PKC isoforms differs between malignant renal cell carcinoma (RCC) and benign oncocytoma. PKCα, a component of the transcription complex in tumors, is up-regulated in benign oncocytoma but down-regulated in RCC. Conversely, miRNA 15a is up-regulated in RCC and down-regulated in oncocytoma. A similar behavior is observed in chromophobe carcinoma, whereas differences are less pronounced in papillary RCC (type I): NF-κB target gene expression (ie, ET-1, ET-A and ET-B receptors, vascular cell adhesion molecule-1, IL-6, and fractalkine) is particularly high in malignant RCCs. Up-regulated miRNA 15a can be measured in urine from patients with RCC but is nearly undetectable in oncocytoma, other tumors, and urinary tract inflammation. Thus, the up-regulation of miRNA 15a may be an important marker to help identify malignant clear-cell RCCs in both biopsy and urine samples.

Protein kinase C α regulates nuclear pri-microRNA 15a release as part of endothelin signaling.

Endothelin-1 induced signaling is characterized by an early induction of a nuclear factor-kappa B p65/mitogen-activated phosphokinase p38 transcription complex via its A-receptor versus a late induction via diacylglycerol, and protein kinase C. A possible interaction between these two pathways and a potential function for protein kinase C in this context has not previously been elucidated. Here we report that in Caki-1 tumor cells, protein kinase C α is a part of the transcription complex. With importin α4 and α5 as chaperones, the transcription complex transmigrates into the nucleus. Protein kinase C α blocks the nuclear release of pri-microRNA 15a by direct binding shown by electrophoretic mobility shift assay and Duolink immune histology. The expression levels of miRNA 15a can be further manipulated by transfection of si-protein kinase C α, or an expression vector containing protein kinase C α or miRNA 15. The miRNA 15a regulation by protein kinase C α is detectable in different malignant human tumor cell lines (renal cell carcinoma, breast carcinoma, and melanoma). Furthermore, all three cell lines harbor both endothelin receptors (ETAR/ETBR). Specific blockage of each receptor leads to major reduction of miRNA 15a expression due to increased nuclear protein kinase C α translocation. We conclude that the nuclear binding of pri-microRNA 15a is a novel function of protein kinase C α, which plays an important role in endothelin-1 mediated signaling. Since several endothelin-sensitive, malignant tumor cell lines harbor this regulation, it could indicate a more general role in tumor biology.

Engraftment of engineered ES cell-derived cardiomyocytes but not BM cells restores contractile function to the infarcted myocardium.

Cellular cardiomyoplasty is an attractive option for the treatment of severe heart failure. It is, however, still unclear and controversial which is the most promising cell source. Therefore, we investigated and examined the fate and functional impact of bone marrow (BM) cells and embryonic stem cell (ES cell)-derived cardiomyocytes after transplantation into the infarcted mouse heart. This proved particularly challenging for the ES cells, as their enrichment into cardiomyocytes and their long-term engraftment and tumorigenicity are still poorly understood. We generated transgenic ES cells expressing puromycin resistance and enhanced green fluorescent protein cassettes under control of a cardiac-specific promoter. Puromycin selection resulted in a highly purified (>99%) cardiomyocyte population, and the yield of cardiomyocytes increased 6-10-fold because of induction of proliferation on purification. Long-term engraftment (4-5 months) was observed when co-transplanting selected ES cell-derived cardiomyocytes and fibroblasts into the injured heart of syngeneic mice, and no teratoma formation was found (n = 60). Although transplantation of ES cell-derived cardiomyocytes improved heart function, BM cells had no positive effects. Furthermore, no contribution of BM cells to cardiac, endothelial, or smooth muscle neogenesis was detected. Hence, our results demonstrate that ES-based cell therapy is a promising approach for the treatment of impaired myocardial function and provides better results than BM-derived cells.

High efficiency capture of biomarker miRNA15a for noninvasive diagnosis of malignant kidney tumors.

To date, there are no preoperative and quantitative dynamics in clinical practice that can reliably differentiate between a benign and malignant renal cell carcinoma (RCC). For monitoring different analytes in body fluids, more than 40 different molecular biomarkers have been identified, however, they are associated with limited clinical sensitivity and/or non-optimal specificity due to their leaky nature. Previous work on RCC demonstrated the miRNA15a to be reliable and novel biomarker with 98.1% specificity and 100% sensitivity. Despite the high potential of miRNA15a biomarker, its clinical application is considerably hampered by the insensitive nature of the detection methods and low concentration of biomarker in samples that is aggravated by the high level of contamination due to other solutes present in body fluids. In this work, a non-invasive quantitative approach is demonstrated to overcome such diagnostics issues through biotin-streptavidin binding and fluorescence active magnetic nanocarriers that ensured prompt isolation, enrichment and purification of the biomarker miRNA15a from urine. The study demonstrates that detectable low levels of these miRNAs through miRNA capturing nanocarriers can potentially function as advanced diagnostic markers for the non-invasive investigation and early detection of renal cancer.

Novel noninvasive marker of regression of clear cell renal cell carcinoma (ccRCC).

OBJECTIVE: Analyzing protein kinase C (PKC) alpha, iota, and zeta as well as levels of Mxi-2 and Vim3 in regressive clear cell renal carcinomas (ccRCCs) and urine samples. MATERIAL AND METHODS: Fresh samples of ccRCCs (predominantly pT1a/b) with different degrees of regression (<10%, 30%, 50%, and 70%) vs normal renal tissue and oncocytomas were studied by Western blot, using antibodies of different PKC isoforms. Urine samples from these tumors were analyzed by ELISA (PKC isoforms, Mxi-2, and Vim3). RESULTS: With increasing degree of regression beyond 10%, nuclear Mxi-2 and Vim3 were highly overexpressed in fresh tumor samples. In urine samples, Vim3 was significantly overexpressed in oncocytoma and downregulated in RCCs with 70% regression. Western blot analysis shows that PKC alpha and iota levels were significantly increased in fresh tumor tissue samples (tumors with 30% regression). PKC zeta was expressed in normal kidney and significantly increased in oncocytoma but not found in ccRCCs. In patients' urines, Mxi-2 was significantly reduced (regression > 50%), while PKC isoform alpha was significantly increased by advanced regression rate. PKC iota in patients' urine was overexpressed in oncocytoma and reduced in all ccRCC urines. CONCLUSION: Tumor regression in ccRCC tissue shows strong nuclear overexpression of Mxi-2, Vim3, and PKC alpha and iota. In respective urines, PKC alpha was overexpressed; PKC iota was decreased. Mxi-2 and Vim3 decreased with increasing regression rates. These reagents could serve as noninvasive ccRCC markers for regression.

Combined paracrine and endocrine AAV9 mediated expression of hepatocyte growth factor for the treatment of renal fibrosis.

In chronic renal disease, tubulointerstitial fibrosis is a leading cause of renal failure. Here, we made use of one of the most promising gene therapy vector platforms, the adeno-associated viral (AAV) vector system, and the COL4A3-deficient mice, a genetic mouse model of renal tubulointerstitial fibrosis, to develop a novel bidirectional treatment strategy to prevent renal fibrosis. By comparing different AAV serotypes in reporter studies, we identified AAV9 as the most suitable delivery vector to simultaneously target liver parenchyma for endocrine and renal tubular epithelium for paracrine therapeutic expression of the antifibrogenic cytokine human hepatocyte growth factor (hHGF). We used transcriptional targeting to drive hHGF expression from the newly developed CMV-enhancer-Ksp-cadherin-promoter (CMV-Ksp) in renal and hepatic tissue following tail vein injection of rAAV9-CMV-Ksp-hHGF into COL4A3-deficient mice. The therapeutic efficiency of our approach was demonstrated by a remarkable attenuation of tubulointerstitial fibrosis and repression of fibrotic markers such as collagen1alpha1 (Col1A1), platelet-derived growth factor receptor-beta (PDGFR-beta), and alpha-smooth muscle actin (SMA). Taken together, our results show the great potential of rAAV9 as an intravenously applicable vector for the combined paracrine and endocrine expression of antifibrogenic factors in the treatment of renal failure caused by tubulointerstitial fibrosis.

Magnetic nanoparticle-based amplification of microRNA detection in body fluids for early disease diagnosis.

Circulating biomarkers such as microRNAs (miRNAs), short noncoding RNA strands, represent prognostic and diagnostic indicators for a variety of physiological disorders making their detection and quantification an attractive approach for minimally invasive early disease diagnosis. However, highly sensitive and selective detection methods are required given the generally low abundance of miRNAs in body fluids together with the presence of large amounts of other potentially interfering biomolecules. Although a variety of miRNA isolation and detection methods have been established in clinics, they usually require trained personnel and often constitute labor-, time- and cost-intensive approaches. During the last years, nanoparticle-based biosensors have received increasing attention due to their superior detection efficiency even in very low concentration regimes. This is based on their unique physicochemical properties in combination with their high surface area that allows for the immobilization of multiple recognition sites resulting in fast and effective recognition of analytes. Among various materials, magnetic nanoparticles have been identified as useful tools for the separation, concentration, and detection of miRNAs. Here, we review state-of-the-art technology with regard to magnetic particle-based miRNA detection from body fluids, critically discussing challenges and future perspective of such biosensors while comparing their handling, sensitivity as well as selectivity against the established miRNA isolation and detection methods.

Poor cell survival limits the beneficial impact of mesenchymal stem cell transplantation on acute kidney injury.

BACKGROUND: Although renal tubular epithelium has a great capacity for repair it has been suggested that the administration of mesenchymal stem cells may accelerate the recovery following severe ischemic injury. METHODS: Here we analyzed the survival rate and organ distribution of transplanted mesenchymal stem cells as well as their contribution to kidney regeneration after ischemic renal injury using functional tests, histological examination as well as quantitative real-time PCR. RESULTS: Intravenously injected stem cells were mainly trapped in lungs and liver. One hour after injection, less than 1% of the injected stem cells could be detected in the injured kidneys. These cells disappeared within the first few days and did not replace renal epithelial cells precluding substantial transdifferentiation. To clarify whether reinforced stem cell delivery might promote sustained survival or conversion to tubular epithelia, stem cells were directly injected into the injured kidneys. Although these grafted cells also did not show sustained survival or contribute to structural renal repair, stem cell injection was associated with a significant but transient initial decrease in serum creatinine. CONCLUSION: These data suggest that mesenchymal stem cells do not significantly contribute to epithelial renewal after ischemic injury, promoting the idea that the major impact of cell-based therapy for acute kidney injury may result from paracrine or endocrine effects unrelated to stem cell transdifferentiation.

Mxi-2 Dependent Regulation of p53 in Prostate Cancer.

BACKGROUND/AIM: Endothelin-1 (ET-1) is overexpressed in many types of cancer, inhibiting the release of the microRNA 15a (miR-15a) and inducing the production of Mxi-2. Our aim was to identify a molecular complex regulating p53 activity in prostate cancer (PCa). MATERIALS AND METHODS: DU145 cells were treated with ET-1, MAPK p38 inhibitor, Endothelin A receptor inhibitor (ETAR inhibitor) and Endothelin B receptor inhibitor (ETBR inhibitor). Extracts were analysed using Western Blot, immunoprecipitation and qRT-PCR. Furthermore, prostate cancer patient samples were analysed using qRT-PCR and ELISA. RESULTS: The hypothesised molecular complex was identified, with miR-15a, microRNA 1285 (miR-1285) and Mxi-2 levels up-regulated in patients in relation to increasing aggressiveness of PCa. CONCLUSION: A complex composed of Argonaut 2 (Ago2)/Mxi-2/miR-1285 is involved in PCa. The expression of Mxi-2 correlates with increasing PCa aggressiveness and might be used as a non-invasive marker for the diagnosis and progression of PCa.

A p38-p65 transcription complex induced by endothelin-1 mediates signal transduction in cancer cells.

Endothelin-1 is a powerful mitogen for various tumor and non-tumor cells. Its signaling cascade induces the inflammatory NF-kappaB complex, leading to expression of a number of target genes. In this context, MAPK p38 has been regarded as a potential phosphate donor for the p65 subunit of NF-kappaB. In the present study in HeLa cells, we have found that ET-1 induced signalling activates the NF-kappaB transcription complex (TC) in the nucleus at 6 h specifically via ET-A - but not ET-B receptor. The TC contains p65, p38 (alpha and beta) - binding to the NLS of p65 in the cytoplasm - as well as p50, but no IkappaBalpha. Specific p38 inhibition by SB203580 or by siRNA interferes markedly with gene expression of several target genes. Complex formation occurs in the cytoplasm, and both transcription factors transmigrate as a complex in the nucleus. Overexpression of p38, treatment with Chrysin, MG132, or dimethylformamide shows dependence of TC on p38 as partner. In other tumor cells lines studied, ET-1 activates TC, with p38 as an important complex partner of p65. TC-induction by ET-1 contains about twice the amount of p38 than by TNFalpha. Thus, p38 may be an additional therapeutic target to control inflammatory gene expression in tumor cells.

Targeting myofibroblasts in model systems of fibrosis by an artificial alpha-smooth muscle-actin promoter hybrid.

Myofibroblasts are the main cell types producing extracellular matrix proteins in a variety of fibrotic diseases. Therefore, they are useful targets for studies of intracellular communication and gene therapeutical approaches in scarring diseases. An artificial promoter containing the -702 bp regulatory sequence of the alpha-smooth muscle actin (SMA) gene linked to the first intron enhancer sequence of the beta-actin gene and the beta-globin intron-exon junction was constructed and tested for myofibroblast-dependent gene expression using the green fluorescent protein as a reporter. Reporter expression revealed myofibroblast-specific function in hepatic and renal myofibroblasts, in vitro. In addition, differentiation-dependent activation of the SMA-beta-actin promoter hybrid was shown after induction of myofibroblastic features in mesangial cells by stretching treatment. Furthermore, wound healing experiments with SMA-beta-actin promoter reporter mice demonstrated myofibroblast-specific action, in vivo. In conclusion, the -702 bp regulatory region of the SMA promoter linked to enhancing beta-actin and beta-globin sequences benefits from its small size and is suggested as a promising tool to target myofibroblasts as the crucial cell type in various scarring processes.