M2 macrophages in the tumor microenvironment are important drivers of cancer metastasis. Exosomes play a critical role in the crosstalk between different cells by delivering microRNAs or other ...cargos. Whether exosomes derived from pro-tumorigenic M2 macrophages (M2-Exos) could modulate the metastatic behavior of renal cell carcinoma (RCC) is unclear. This study found that M2-Exos promotes migration and invasion in RCC cells. Inhibiting miR-21-5p in M2-Exos significantly reversed their pro-metastatic effects on RCC cells in vitro and in the avian embryo chorioallantoic membrane in vivo tumor model. We further found that the pro-metastatic mechanism of miR-21-5p in M2-Exos is by targeting PTEN-3'UTR to regulate PTEN/Akt signaling. Taken together, our results demonstrate that M2-Exos carries miR-21-5p promote metastatic features of RCC cells through PTEN/Akt signaling. Reversing this could serve as a novel approach to control RCC metastasis.
Exosomes are extracellular vesicles that modulate essential physiological and pathological signals. Communication between cancer cells that express the
tumor suppressor gene and those that do not is ...instrumental to distant metastasis in renal cell carcinoma (RCC). In a novel metastasis model, VHL(-) cancer cells are the metastatic driver, while VHL(+) cells receive metastatic signals from VHL(-) cells and undergo aggressive transformation. This study investigates whether exosomes could be mediating metastatic crosstalk. Exosomes isolated from paired VHL(+) and VHL(-) cancer cell lines were assessed for physical, biochemical, and biological characteristics. Compared to the VHL(+) cells, VHL(-) cells produce significantly more exosomes that augment epithelial-to-mesenchymal transition (EMT) and migration of VHL(+) cells. Using a Cre-
exosome reporter system, the fluorescent color conversion and migration were correlated with dose-dependent delivery of VHL(-) exosomes. VHL(-) exosomes even induced a complete cascade of distant metastasis when added to VHL(+) tumor xenografts in a duck chorioallantoic membrane (dCAM) model, while
(+) exosomes did not. Therefore, this study supports that exosomes from VHL(-) cells could mediate critical cell-to-cell crosstalk to promote metastasis in RCC.
Abstract Background and Aims Patients with kidney disease, especially those on dialysis, are more susceptible to infections such as peritonitis, sepsis, pneumonia, and are at a higher risk for ...infection-related mortality. Pathogenic mechanisms underlying the secondary immunodeficiency in kidney disease include gut dysbiosis and barrier dysfunction, persistent inflammation, immune paralysis due to increased levels of immunoregulatory metabolites (e.g. uric acid) and proteins (e.g. FGF23) 1. Currently, it is unknown whether CKD-related hyperuricemia may contribute to the immune paralysis in this context. We hypothesized that hyperuricemia (HU) may aggravate the innate immune response to infection in CKD in mice. Method Mono- and polybacterial sepsis was induced by LPS injection or cecal ligation and puncture in Alb-creERT2;Glut9lox/lox mice with HU and/or CKD, and in Glut9lox/lox (healthy) control mice. After 24 hours, systemic inflammation was evaluated by measuring serum cytokine levels, immune cell activation and recruitment, and neutrophil extracellular trap release. Tissue injury in liver, heart, and kidney was assessed by performing RT-qPCR and immunohistochemistry. In addition, kidney function was determined by measuring the glomerular filtration rate (GFR). Additionally, mice were treated with urate-lowering therapy to reduce serum uric acid levels and the immune response and functional outcomes after sepsis is quantified. Results We found that both mono- and polybacterial sepsis caused systemic inflammation as indicated by an increased number of blood neutrophils (see Figure), neutrophil activation and pro-inflammatory cytokine levels as compared to the PBS-treated or sham-operated control groups in Glut9lox/lox healthy mice, respectively. Mice with sepsis also displayed a slightly worsened kidney function. Interestingly, HU significantly increased neutrophil numbers but decreased their activation status and the ability of neutrophils to form neutrophil extracellular traps in Alb-creERT2;Glut9lox/lox mice with sepsis as compared to the control groups, which was further aggravated in mice with CKD-related HU (CKD+HU). This impaired inflammatory response was partially reversible by lowering serum uric acid with febuxostat. Conclusion Our results identify hyperuricemia related or unrelated to kidney disease as immune regulator in bacterial infection by suppressing neutrophil functions in mice. Specifically targeting uric acid may help to overcome the secondary immunodeficiency related to kidney disease during infection but enhances sterile inflammation 2.
Abstract Background and Aims Chronic kidney disease (CKD) is one of the most common diseases affecting 8-16% of the world population. Beside cardiovascular complications, infections including sepsis ...are the second most common cause of death in patients with acute kidney injury (AKI) and CKD. However, the underlying pathomechanisms that contribute to the secondary immunodeficiency related to kidney disease 1 are not well understood. Recent evidence suggests that CKD-related hyperuricemia characterised by elevated serum uric acid (UA) levels suppresses immune cell functions during sterile inflammation 2. Whether this is also the case during host defense is subject of our current investigation. In this study, we hypothesized that soluble UA inhibits neutrophil effector functions and therefore contributes to the increased infection risk in patients with kidney disease. Method Blood neutrophils were isolated from healthy individuals as well as from patients with kidney diseases, and incubated ex vivo in the presence or absence of 10 mg/dl soluble UA prior to stimulation with bacterial peptides including LPS. Immune cell functions including cytoskeletal changes, immune cell activation, maturation, endo- and phagocytosis (pHrodo Dextran particles, IgG-FITC beads, pHrodo E. coli bioparticles), ROS production, and neutrophil extracellular trap (NET) formation were analysed and quantified using flow cytometry, fluorescence and colorimetric assays, and fluorescence microscopy. In addition, to verify our results we stimulated neutrophils from healthy individuals with sera from hyperuricemic CKD patients. Results Our results show for the first time that soluble UA significantly inhibits the ability of neutrophils to endocytose small particles and phagocytose beads in neutrophils from healthy individuals comparable to the inhibitory effect of Cytochalasin D, an inhibitor of endo- and phagocytosis. Interestingly, unlike neutrophils from AKI patients, neutrophils from CKD patients were significantly less able to phagocytose beads compared to healthy controls with and without stimulation. To mimic the uptake of pathogens more physiologically, pHrodo E. coli bioparticles were used. We found that soluble UA inhibited the phagocytosis of such bioparticles in neutrophils. In addition, our investigation into the formation of ROS showed that soluble UA inhibited specifically nitric oxide, peroxynitrite, hydroxyl radicals and hydrogen peroxide, but to a lower extent the formation of superoxides in neutrophils from healthy individuals, similar to the effectiveness of the radical scavenger N-acetylcysteine. These data were comparable with our cohort study of neutrophils from CKD patients. To examine the mechanism of reduced ROS production, we inhibited NADPH oxidase (DPI) and MPO (4-ABAH) in neutrophils and found that soluble UA has similar inhibitory effects on ROS production like DPI whereas 4-ABAH was more potent. This indicated that soluble UA modulates NADPH oxidase and ROS production, which subsequently resulted in reduced NET formation in neutrophils. Conclusion Our data identify soluble UA as potential immune regulator of the secondary immunodeficiency in patients with kidney disease by inhibiting the endo- and phagocytosis of particles, NADPH-mediated ROS production and NET formation in neutrophils, processes that are important to kill pathogens and fight an infection. Thus, specifically targeting UA with urate-lowering therapy might overcome the suppressed host defence against infection in patients with kidney disease.
Neutrophils, the most abundant white blood cells in the human circulation, play crucial roles in various diseases, including kidney disease. Traditionally viewed as short-lived pro-inflammatory ...phagocytes that release reactive oxygen species, cytokines and neutrophil extracellular traps, recent studies have revealed their complexity and heterogeneity, thereby challenging this perception. Neutrophils are now recognized as transcriptionally active cells capable of proliferation and reverse migration, displaying phenotypic and functional heterogeneity. They respond to a wide range of signals and deploy various cargo to influence the activity of other cells in the circulation and in tissues. They can regulate the behavior of multiple immune cell types, exhibit innate immune memory, and contribute to both acute and chronic inflammatory responses while also promoting inflammation resolution in a context-dependent manner. Here, we explore the origin and heterogeneity of neutrophils, their functional diversity, and the cues that regulate their effector functions. We also examine their emerging role in infectious and non-infectious diseases with a particular emphasis on kidney disease. Understanding the complex behavior of neutrophils during tissue injury and inflammation may provide novel insights, thereby paving the way for potential therapeutic strategies to manage acute and chronic conditions. By deciphering their multifaceted role, targeted interventions can be developed to address the intricacies of neutrophil-mediated immune responses and improve disease outcomes.
Metastatic Renal Cell Carcinoma(RCC) has limited safe and effective treatments available. This is due to a lack of understanding relating to the mechanism of distant cancer metastasis. Metastatic ...crosstalk occurs between pseudo-hypoxic von Hippel-Lindau(VHL) knockout tumor cells and VHL wildtype tumor cells. VHL knockout cells have increased production of exosomes due to their pseudo-hypoxic state to help cells adapt to hypoxic conditions. VHL knockout-derived exosomes increase the metastatic properties of VHL wildtype recipient cells. Metastatic properties such as migration and metastasis occur in response between isolated exosomes from the CRISPR modified VHL(-) Renca murine line and VHL(+) cells, generating a model of RCC metastasis and the potential to develop targeted diagnostics and therapeutics for metastatic disease.
Mechanisms driving resistance to cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in hormone receptor-positive (HR
) breast cancer have not been clearly defined. Whole-exome sequencing of 59 tumors ...with CDK4/6i exposure revealed multiple candidate resistance mechanisms including
loss, activating alterations in
, and
, and loss of estrogen receptor expression.
experiments confirmed that these alterations conferred CDK4/6i resistance. Cancer cells cultured to resistance with CDK4/6i also acquired
, or
alterations, which conferred sensitivity to AURKA, ERK, or CHEK1 inhibition. Three of these activating alterations-in
, and
-have not, to our knowledge, been previously demonstrated as mechanisms of resistance to CDK4/6i in breast cancer preclinically or in patient samples. Together, these eight mechanisms were present in 66% of resistant tumors profiled and may define therapeutic opportunities in patients. SIGNIFICANCE: We identified eight distinct mechanisms of resistance to CDK4/6i present in 66% of resistant tumors profiled. Most of these have a therapeutic strategy to overcome or prevent resistance in these tumors. Taken together, these findings have critical implications related to the potential utility of precision-based approaches to overcome resistance in many patients with HR
metastatic breast cancer.
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