The Transcription Factor Ets1 Influences Axonal Growth via Regulation of Lcn2

Transcription factors are essential for the development and regeneration of the nervous system. The current study investigated key regulatory transcription factors in rat spinal cord development via RNA sequencing. The hub gene Ets1 was highly expressed in the spinal cord during the embryonic period, and then its expression decreased during spinal cord development. Knockdown of Ets1 significantly increased the axonal growth of cultured spinal cord neurons. Luciferase reporter assays and chromatin immunoprecipitation assays indicated that Ets1 could directly bind to the Lcn2 promoter and positively regulate Lcn2 transcription. In conclusion, these findings provide the first direct evidence that Ets1 regulates axon growth by controlling Lcn2 expression, and Ets1 may be a novel therapeutic target for axon regeneration in the central nervous system.

Sex-Specific Appetite Regulation of Lipocalin-2 in High-Fat-Diet-Induced Obese Mice

INTRODUCTION

Lipocalin 2 (Lcn2) is a key factor in appetite suppression. However, the effect of Lcn2 on appetite in terms of sex differences has not been thoroughly studied.

METHODS

Young (3-month-old) whole-body Lcn2 knockout (Lcn2-/-) mice were fed a normal diet (ND) or high-fat diet (HFD) for 8 weeks to investigate obesity, food intake, serum metabolism, hepatic lipid metabolism, and regulation of gastrointestinal hormones.

RESULTS

Lcn2 deficiency significantly increased the body weight and food intake of male mice when fed ND instead of HFD and females when fed HFD but not ND. Compared to wild-type (WT) male mice, the adiponectin level and phosphorylated form of adenosine 5'-monophosphate-activated protein kinase (AMPK) in the hypothalamus were both increased in ND-fed Lcn2-/- male mice but decreased in HFD-fed Lcn2-/- male mice. However, in female mice, adiponectin and its energy metabolism pathway were not altered. Instead, estradiol was found to be substantially higher in ND-fed Lcn2-/- female mice and substantially lower in HFD-fed Lcn2-/- female mice compared with WT female mice. Estradiol alteration also caused similar changes in ERα in the hypothalamus, leading to changes in the PI3K/AKT energy metabolism pathway. It suggested that the increased appetite caused by Lcn2 deficiency in male mice may be due to increased adiponectin expression and promotion of AMPK phosphorylation, while in female mice it may be related to the decrease of circulating estradiol and the inhibition of the hypothalamic ERα/PI3K/AKT energy metabolism pathway.

CONCLUSION

Lcn2 plays in a highly sex-specific manner in the regulation of appetite in young mice.

Transient ischemic stroke triggers sustained damage of the choroid plexus blood-CSF barrier

Neuroinflammation is a pathological event associated with many neurological disorders, including dementia and stroke. The choroid plexus (ChP) is a key structure in the ventricles of the brain that secretes cerebrospinal fluid (CSF), forms a blood-CSF barrier, and responds to disease conditions by recruiting immune cells and maintaining an immune microenvironment in the brain. Despite these critical roles, the exact structural and functional changes to the ChP over post-stroke time remain to be elucidated. We induced ischemic stroke in C57BL/6J mice via transient middle cerebral artery occlusion which led to reduction of cerebral blood flow and infarct stroke. At 1-7 days post-stroke, we detected time-dependent increase in the ChP blood-CSF barrier permeability to albumin, tight-junction damage, and dynamic changes of SPAK-NKCC1 protein complex, a key ion transport regulatory system for CSF production and clearance. A transient loss of SPAK protein complex but increased phosphorylation of the SPAK-NKCC1 complex was observed in both lateral ventricle ChPs. Most interestingly, stroke also triggered elevation of proinflammatory Lcn2 mRNA and its protein as well as infiltration of anti-inflammatory myeloid cells in ChP at day 5 post-stroke. These findings demonstrate that ischemic strokes cause significant damage to the ChP blood-CSF barrier, contributing to neuroinflammation in the subacute stage.

Lcn2 deficiency accelerates the infection of Escherichia coli O157:H7 by disrupting the intestinal barrier function

Bacterial infections result in intestinal inflammation and injury, which affects gut health and nutrient absorption. Lipocalin 2 (Lcn2) is a protein that reacts to microbial invasion, inflammatory responses, and tissue damage. However, it remains unclear whether Lcn2 has a protective effect against bacterial induced intestinal inflammation. Therefore, this study endeavors to investigate the involvement of Lcn2 in the intestinal inflammation of mice infected with Enterohemorrhagic Escherichia coli O157:H7 (E. coli O157:H7). Lcn2 knockout (Lcn2-/-) mice were used to evaluate the changes of inflammatory responses. Lcn2 deficiency significantly exacerbated clinical symptoms of E. coli O157:H7 infection by reducing body weight and encouraging bacterial colonization of. Compared to infected wild type mice, infected Lcn2-/- mice had significantly elevated levels of pro-inflammatory cytokines in serum and ileum, including interleukin (IL)-6, IL-1β, and tumor necrosis factor-α (TNF-α), as well as severe villi destruction in the jejunum. Furthermore, Lcn2 deficiency aggravated intestinal barrier degradation by significantly reducing the expression of tight junction proteins occludin and claudin 1, the content of myeloperoxidase (MPO) in the ileum, and the number of goblet cells in the colon. Our findings indicated that Lcn2 could alleviate inflammatory damage caused by E. coli O157:H7 infection in mice by enhancing intestinal barrier function.

Hepatocytic lipocalin-2 controls HDL metabolism and atherosclerosis via Nedd4-1-SR-BI axis in mice

High-density lipoprotein (HDL) metabolism is regulated by complex interplay between the scavenger receptor group B type 1 (SR-BI) and multiple signaling molecules in the liver. Here, we show that lipocalin-2 (Lcn2) is a key regulator of hepatic SR-BI, HDL metabolism, and atherosclerosis. Overexpression of human Lcn2 in hepatocytes attenuates the development of atherosclerosis via SR-BI in western-diet-fed Ldlr-/- mice, whereas hepatocyte-specific ablation of Lcn2 has the opposite effect. Mechanistically, hepatocyte Lcn2 improves HDL metabolism and alleviates atherogenesis by blocking Nedd4-1-mediated SR-BI ubiquitination at K500 and K508. The Lcn2-improved HDL metabolism is abolished in mice with hepatocyte-specific Nedd4-1 or SR-BI deletion and in SR-BI (K500A/K508A) mutation mice. This study identifies a regulatory axis from Lcn2 to HDL via blocking Nedd4-1-mediated SR-BI ubiquitination and demonstrates that hepatocyte Lcn2 may be a promising target to improve HDL metabolism to treat atherosclerotic cardiovascular diseases.

Lipocalin 2 in the Paraventricular Thalamic Nucleus Contributes to DSS-Induced Depressive-Like Behaviors

The incidence rate of anxiety and depression is significantly higher in patients with inflammatory bowel diseases (IBD) than in the general population. The mechanisms underlying dextran sulfate sodium (DSS)-induced depressive-like behaviors are still unclear. We clarified that IBD mice induced by repeated administration of DSS presented depressive-like behaviors. The paraventricular thalamic nucleus (PVT) was regarded as the activated brain region by the number of c-fos-labeled neurons. RNA-sequencing analysis showed that lipocalin 2 (Lcn2) was upregulated in the PVT of mice with DSS-induced depressive behaviors. Upregulating Lcn2 from neuronal activity induced dendritic spine loss and the secreted protein induced chemokine expression and subsequently contributed to microglial activation leading to blood-brain barrier permeability. Moreover, Lcn2 silencing in the PVT alleviated the DSS-induced depressive-like behaviors. The present study demonstrated that elevated Lcn2 in the PVT is a critical factor for DSS-induced depressive behaviors.

Lipocalin-2 production by astrocytes in response to high concentrations of glutamate

AIMS

Glutamate-induced excitotoxicity is mainly mediated by neuronal NMDA receptors; however, it is unclear how astrocytes are involved in this phenomenon. This study aimed to explore the effects of excess glutamate on astrocytes both in vitro and in vivo.

METHODS

We used astrocyte-enriched cultures (AECs), in which microglia were removed from mixed glial cultures, to investigate the effects of extracellular glutamate on these cells by microarray, quantitative PCR, ELISA, and immunostaining. We also examined the production of lipocalin-2 (Lcn2) by immunohistochemistry in the brains of mice after status epilepticus induced by pilocarpine and by ELISA in the cerebrospinal fluid (CSF) of patients characterised by status epilepticus.

RESULTS

Microarray analysis identified Lcn2 as a factor upregulated in AECs by excess glutamate; glutamate addition increased Lcn2 in the cytoplasm of astrocytes and AECs released Lcn2 in a concentration-dependent manner. Lcn2 production was reduced by chemical inhibition of metabotropic glutamate receptor 3 or siRNA knockdown. Furthermore, Lcn2 was increased in the astrocytes of a status epilepticus mouse model and in the CSF of human patients.

CONCLUSION

These results indicate that astrocytes stimulate Lcn2 production via metabotropic glutamate receptor 3 in response to high concentrations of glutamate.

Kdm6a deficiency in microglia/macrophages epigenetically silences Lcn2 expression and reduces photoreceptor dysfunction in diabetic retinopathy

Diabetic retinopathy (DR) is one of the leading causes of severe visual impairment worldwide. However, the role of adaptive immune inflammation driven by microglia/macrophages in DR is not yet well elucidated. Kdm6a is a histone demethylase that removes the trimethyl groups of histones H3K27 and plays important biological roles in activating target genes. To elucidate the role of Kdm6a in microglia/macrophages in diabetic retinas, we established diabetic animal models with conditional knockout mice to investigate the impacts of Kdm6a deficiency. The RNA-seq analysis, mass spectrum examination, immunohistochemistry and detection of enzyme activities were used to elucidate the effect of Kdm6a deletion on gene transcription in microglia/macrophages. The expression of Kdm6a was increased in the retinas of diabetic mice compared to the control group. Loss of Kdm6a in microglia/macrophages ameliorated the diabetes-induced retinal thickness decrease, inflammation, and visual impairment. Kdm6a in microglia/macrophages regulated Lcn2 expression in a demethylase activity-dependent manner and inhibited glycolysis progression in photoreceptor cells through Lcn2. These results suggest that Kdm6a in microglia/macrophages aggravated diabetic retinopathy by promoting the expression of Lcn2 and impairing glycolysis progression in photoreceptor cells.

Lcn2 mediates adipocyte-muscle-tumor communication and hypothermia in pancreatic cancer cachexia

OBJECTIVE

Adipose tissue is the largest endocrine organ. When activated by cancer cells, adipocytes secrete adipocytokines and release fatty acids, which are then transferred to cancer cells and used for structural and biochemical support. How this metabolic symbiosis between cancer cells and adipocytes affects skeletal muscle and thermogenesis during cancer cachexia is unknown. Cancer cachexia is a multiorgan syndrome and how the communication between tissues is established has yet to be determined. We investigated adipose tissue secretory factors and explored their role in crosstalk of adipocytes, muscle, and tumor during pancreatic cancer cachexia.

METHODS

We used a pancreatic cancer cachexia mouse model generated by syngenic implantation of pancreatic ductal adenocarcinoma (PDAC) cells (KPC) intraperitoneally into C57BL/6 mice and Lcn2-knockout mice. For in vitro studies, adipocytes (3T3-L1 and primary adipocytes), cachectic cancer cells (Panc0203), non-cachectic cancer cells (Du145 cells), and skeletal muscle cells (C2C12 myoblasts) were used.

RESULTS

To identify molecules involved in the crosstalk of adipose tissue with muscle and tumors, we treated 3T3-L1 adipocytes with conditioned medium (CM) from cancer cells. Upon screening the secretomes from PDAC-induced adipocytes, several adipocytokines were identified, including lipocalin 2 (Lcn2). We investigated Lcn2 as a potential mediator of cachexia induced by adipocytes in response to PDAC. During tumor progression, mice exhibited a decline in body weight gain, which was accompanied by loss of adipose and muscle tissues. Tumor-harboring mice developed drastic hypothermia because of a dramatic loss of fat in brown adipose tissue (BAT) and suppression of the thermogenesis pathway. We inhibited Lcn2 with an anti-Lcn2 antibody neutralization or genomic ablation in mice. Lcn2 deficiency significantly improved body temperature in tumor-bearing mice, which was supported by the increased expression of Ucp1 and β3-adrenergic receptor in BAT. In addition, Lcn2 inhibition abrogated the loss of fat and muscle in tumor-bearing mice. In contrast to tumor-bearing WT mice, the corresponding Lcn2-knockout mice showed reduced ATGL expression in iWAT and decreased the expression of muscle atrophy molecular markers MuRF-1 and Fbx32.

CONCLUSIONS

This study showed that Lcn2 is causally involved in the dysregulation of adipose tissue-muscle-tumor crosstalk during pancreatic cancer cachexia. Therapeutic targets that suppress Lcn2 may minimize the progression of cachexia.

Photobiomodulation inhibits the activation of neurotoxic microglia and astrocytes by inhibiting Lcn2/JAK2-STAT3 crosstalk after spinal cord injury in male rats

BACKGROUND

Neurotoxic microglia and astrocytes begin to activate and participate in pathological processes after spinal cord injury (SCI), subsequently causing severe secondary damage and affecting tissue repair. We have previously reported that photobiomodulation (PBM) can promote functional recovery by reducing neuroinflammation after SCI, but little is known about the underlying mechanism. Therefore, we aimed to investigate whether PBM ameliorates neuroinflammation by modulating the activation of microglia and astrocytes after SCI.

METHODS

Male Sprague-Dawley rats were randomly divided into three groups: a sham control group, an SCI + vehicle group and an SCI + PBM group. PBM was performed for two consecutive weeks after clip-compression SCI models were established. The activation of neurotoxic microglia and astrocytes, the level of tissue apoptosis, the number of motor neurons and the recovery of motor function were evaluated at different days post-injury (1, 3, 7, 14, and 28 days post-injury, dpi). Lipocalin 2 (Lcn2) and Janus kinase-2 (JAK2)-signal transducer and activator of transcription-3 (STAT3) signaling were regarded as potential targets by which PBM affected neurotoxic microglia and astrocytes. In in vitro experiments, primary microglia and astrocytes were irradiated with PBM and cotreated with cucurbitacin I (a JAK2-STAT3 pathway inhibitor), an adenovirus (shRNA-Lcn2) and recombinant Lcn2 protein.

RESULTS

PBM promoted the recovery of motor function, inhibited the activation of neurotoxic microglia and astrocytes, alleviated neuroinflammation and tissue apoptosis, and increased the number of neurons retained after SCI. The upregulation of Lcn2 and the activation of the JAK2-STAT3 pathway after SCI were suppressed by PBM. In vitro experiments also showed that Lcn2 and JAK2-STAT3 were mutually promoted and that PBM interfered with this interaction, inhibiting the activation of microglia and astrocytes.

CONCLUSION

Lcn2/JAK2-STAT3 crosstalk is involved in the activation of neurotoxic microglia and astrocytes after SCI, and this process can be suppressed by PBM.

Lipocalin-2 Alleviates LPS-Induced Inflammation Through Alteration of Macrophage Properties

Purpose

Lipocalin-2 (Lcn2) is an acute-phase protein and elevated in several inflammatory diseases. This study aimed to determine whether Lcn2 alleviates inflammation and explore the underlying cellular mechanisms.

Methods

C57BL/6 Lcn2-deficient (Lcn2^−/-) male mice were intraperitoneally injected with lipopolysaccharide (LPS) to build systemic inflammation model. The inflammatory processes were investigated. The morphology of villi was measured by scanning electron microscopy (SEM). The levels of inflammatory factors were detected by ELISA and qPCR analysis. The production of Lcn2 was determined with immunofluorescence staining by confocal microscope. The molecular mechanism of Lcn2 in bone marrow-derived macrophages (BMDMs) was analyzed by mass spectrometry (MS)-based quantitative proteomic analysis.

Results

Compared to wild-type (WT) mice injected with LPS, Lcn2^−/- mice injected with LPS showed increased inflammatory damage in jejunum and ileum, and significantly elevated the levels of multiple pro-inflammatory cytokines. After determining that Lcn2 was mainly located in the cytoplasm of macrophages, we isolated BMDMs from Lcn2^−/- mice to evaluate their function. During LPS challenge, transcripts of pro-inflammatory cytokines were all significantly increased in BMDMs from Lcn2^−/- mice, while those of anti-inflammatory cytokines were significantly decreased when compared with the cytokines in BMDMs from WT mice. A label-free relative quantitation proteomics analysis showed that LPS-treated BMDMs from Lcn2^−/- mice had elevated levels of pro-inflammatory pathways, but reduced phagocytosis and autophagy when compared with LPS-treated BMDMs from WT mice.

Conclusion

These findings demonstrated that Lcn2 was a potent protective factor in response to systemic inflammation and might be an indispensable factor for macrophage functions.

Iron in immune cell function and host defense

The control over iron availability is crucial under homeostatic conditions and even more in the case of an infection. This results from diverse properties of iron: first, iron is an important trace element for the host as well as for the pathogen for various cellular and metabolic processes, second, free iron catalyzes Fenton reaction and is therefore producing reactive oxygen species as a part of the host defense machinery, third, iron exhibits important effects on immune cell function and differentiation and fourth almost every immune activation in turn impacts on iron metabolism and spatio-temporal iron distribution. The central importance of iron in the host and microbe interplay and thus for the course of infections led to diverse strategies to restrict iron for invading pathogens. In this review, we focus on how iron restriction to the pathogen is a powerful innate immune defense mechanism of the host called "nutritional immunity". Important proteins in the iron-host-pathogen interplay will be discussed as well as the influence of iron on the efficacy of innate and adaptive immunity. Recently described processes like ferritinophagy and ferroptosis are further covered in respect to their impact on inflammation and infection control and how they impact on our understanding of the interaction of host and pathogen.

Osteoblast-derived lipocalin-2 regulated by miRNA-96-5p/Foxo1 advances the progression of Alzheimer's disease

Aim: Alzheimer's disease (AD) is the most frequent cause of dementia and characterized by the accumulation of β-amyloid peptides in plaques and vessel walls. This study proposed a hypothesis of an inhibitory role of miR-96-5p in AD via regulating Foxo1. Methods & methods: AD mouse models were established by injecting with 1% pentobarbital. Results: Knockdown of miR-96-5p in the presence of naringin was shown to reduce the expression of Foxo1 and contents of superoxide dismutase, catalase and glutathione peroxidase, yet increase lipocalin-2 expression as well as hydroxyproline and malondialdehyde contents. Also, Foxo1-mediated lipocalin-2 inhibition attenuated AD. Conclusion: Our study shows downregulating miR-96-5p limited AD progression, highlighting miR-96-5p a potential therapeutic target in treating AD.

Lipocalin-2 Functions as Inhibitor of Innate Resistance to Mycobacterium tuberculosis

Lipocalin-2 is a constituent of the neutrophil secondary granules and is expressed de novo by macrophages and epithelium in response to inflammation. Lipocalin-2 acts in a bacteriostatic fashion by binding iron-loaded siderophores required for bacterial growth. Mycobacterium tuberculosis (M.tb) produces siderophores that can be bound by lipocalin-2. The impact of lipocalin-2 in the innate immune response toward extracellular bacteria has been established whereas the effect on intracellular bacteria, such as M.tb, is less well-described. Here we show that lipocalin-2 surprisingly confers a growth advantage on M.tb in the early stages of infection (3 weeks post-challenge). Using mixed bone marrow chimeras, we demonstrate that lipocalin-2 derived from granulocytes, but not from epithelia and macrophages, leads to increased susceptibility to M.tb infection. In contrast, lipocalin-2 is not observed to promote mycobacterial growth at later stages of M.tb infection. We demonstrate co-localization of granulocytes and mycobacteria within the nascent granulomas at week 3 post-challenge, but not in the consolidated granulomas at week 5. We hypothesize that neutrophil-derived lipocalin-2 acts to supply a source of iron to M.tb in infected macrophages within the immature granuloma, thereby facilitating mycobacterial growth.

Tumor associated macrophages deliver iron to tumor cells via Lcn2

Cancer cells exhibit an increasing iron demand associated with the tumor progression. But the mechanism of iron accumulation in the tumor microenvironment is still unclear. Tumor associated macrophages (TAMs) in the tumor microenvironment may act as extra iron source. However, evidence is still lacking in TAMs as iron donors. In the present study, we found that iron concentration was significantly increased at tumor metastatic stage, which could be attributed to up-regulated expression of lipocalin2 (Lcn2). TAMs in the microenvironment secreted Lcn2. Moreover, TAMs increased intracellular iron concentration in tumor cells via Lcn2 as transporter, which could be restored by Lcn2 antibody neutralization. In conclusion, TAMs increased intracellular iron concentration of the tumor cells via Lcn2 which acted as an iron transporter. Targeting Lcn2 secretion in TAMs to "starve cancer cells" could act as alternative option for tumor therapy.

Lipocalin2 Protects Human Embryonic Kidney Cells against Cisplatin-Induced Genotoxicity

Cisplatin is one of the most useful chemotherapeutics which performs its cytotoxic effect via accumulation of platinum resulting in oxidative stress, and destruction of cell DNA. This could probably cause secondary cancers in healthy tissues. Lipocalin2 (Lcn2) is a protein which its expression is increased in oxidative stresses. Therefore, the present study was performed to evaluate the protective effects of Lcn2 up-regulation on cisplatin genotoxicity. In order to up-regulate Lcn2 expression, HEK293 cells were transfected with pcDNA3.1-Lcn2 vector. Afterwards, stable cells consistently expressing Lcn2 were selected via screening with G418 antibiotic. Next, overexpression of Lcn2 was evaluated by RT-PCR and ELISA, comparing to the control non-transfected cells. Then, in order to evaluate the cytoprotective effects of Lcn2 overexpression, transfected and non-transfected cells were subjected to cisplatin treatment followed by MTT and alkaline Comet assays. RT-PCR and ELISA assays confirmed up-regulation of Lcn2 by the stable cells. MTT assay of the Lcn2 over-expressing cells showed higher IC50 values comparing to the non-transfected cells. Furthermore, the Comet assay confirmed Lcn2 protective effects on the cisplatin (1 µg/mL) induced genotoxicity. In the present study, for the first time, we showed the protective effect of Lcn2 on cisplatin induced genotoxicity. Therefore, one of the probable mechanisms of Lcn2 cytoprotctive effects under oxidative stress conditions could be due to the prevention of genotoxicity. However, further evaluations in this regard must be considered.

Siderophores in Iron Metabolism: From Mechanism to Therapy Potential

Iron is an essential nutrient for life. During infection, a fierce battle of iron acquisition occurs between the host and bacterial pathogens. Bacteria acquire iron by secreting siderophores, small ferric iron-binding molecules. In response, host immune cells secrete lipocalin 2 (also known as siderocalin), a siderophore-binding protein, to prevent bacterial reuptake of iron-loaded siderophores. To counter this threat, some bacteria can produce lipocalin 2-resistant siderophores. This review discusses the recently described molecular mechanisms of siderophore iron trafficking between host and bacteria, highlighting the therapeutic potential of exploiting pathogen siderophore machinery for the treatment of antibiotic-resistant bacterial infections. Because the latter reflect a persistent problem in hospital settings, siderophore-targeting or siderophore-based compounds represent a promising avenue to combat such infections.

Identification of potential biomarkers for post-traumatic complications released after trauma-hemorrhage from murine Kupffer cells and its investigation in lung and liver

CONTEXT

Early diagnosis of complications after severe trauma by specific biomarkers remains difficult.

OBJECTIVE

Identify potential new biomarkers for early diagnosis of post-traumatic complications.

MATERIAL AND METHODS

Mice underwent pressure-controlled hemorrhage or sham procedure. Four hours later, genome-wide expression of isolated Kupffer cells was compared with controls using Affymetrix-Genechip-Expression-Analysis and real-time-PCR.

RESULTS

Expression analysis and real-time-PCR revealed a significant increase of gene expression of Cxcl10, Il4ra, Csf2rb2, Lcn2, and Gbp5.

CONCLUSION

Cxcl10, Il4ra, Csf2rb2, Lcn2, and Gbp5 might represent new biomarkers for early diagnosis of post-traumatic complications, if they are linked to the development of post-traumatic complications.

Roles of NGAL and MMP-9 in the tumor microenvironment and sensitivity to targeted therapy. Biochim Biophys Acta. 2016;1863:438-448. [PMID: 26278055 DOI: 10.1016/j.bbamcr.2015.08.010]

Various, diverse molecules contribute to the tumor microenvironment and influence invasion and metastasis. In this review, the roles of neutrophil gelatinase-associated lipocalin (NGAL) and matrix metalloproteinase-9 (MMP-9) in the tumor microenvironment and sensitivity to therapy will be discussed. The lipocalin family of proteins has many important functions. For example when NGAL forms a complex with MMP-9 it increases its stability which is important in cancer metastasis. Small hydrophobic molecules are bound by NGAL which can alter their entry into and efflux from cells. Iron transport and storage are also influenced by NGAL activity. Regulation of iron levels is important for survival in the tumor microenvironment as well as metastasis. Innate immunity is also regulated by NGAL as it can have bacteriostatic properties. NGAL and MMP-9 expression may also affect the sensitivity of cancer cells to chemotherapy as well as targeted therapy. Thus NGAL and MMP-9 play important roles in key processes involved in metastasis as well as response to therapy. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.

Co-culture of bone marrow-derived mesenchymal stem cells overexpressing lipocalin 2 with HK-2 and HEK293 cells protects the kidney cells against cisplatin-induced injury

Conditioned medium of mesenchymal stem cells (MSCs) is now being used for its cytoprotective effects, especially when the cells are equipped with cytoprotective factors to strengthen them against unfavorable microenvironments. Overexpression of Lcn2 in MSCs mimics in vivo kidney injury. Hence, unraveling how Lcn2-engineered MSCs affect kidney cells has been investigated. Cisplatin treated HK-2 or HEK293 kidney cells were co-cultivated with Lcn2 overexpressing MSCs in upper and lower chambers of transwell plates. Proliferation, apoptosis, and expression of growth factors and cytokines were assessed in the kidney cells. Co-cultivation with the MSCs-Lcn2 not only inhibited cisplatin-induced cytotoxicity in the HK-2 and HEK293 cells, but increased proliferation rate, prevented cisplatin-induced apoptosis, and increased expression of growth factors and the amount of antioxidants in the kidney cells. Thus Lcn2-engineered MSCs can ameliorate and repair injured kidney cells in vitro, which strongly suggests there are beneficial effects of the MSCs-Lcn2 in cell therapy of kidney injury.

Profiling the genes affected by pathogenic TDP-43 in astrocytes

Mutation in TAR DNA binding protein 43 (TDP-43) is a causative factor of amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Neurodegeneration may not require the presence of pathogenic TDP-43 in all types of relevant cells. Rather, expression of pathogenic TDP-43 in neurons or astrocytes alone is sufficient to cause cell-autonomous or non-cell-autonomous neuron death in transgenic rats. How pathogenic TDP-43 in astrocytes causes non-cell-autonomous neuron death, however, is not clear. Here, we examined the effect of pathogenic TDP-43 on gene expression in astrocytes. Microarray assay revealed that pathogenic TDP-43 in astrocytes preferentially altered expression of the genes encoding secretory proteins. Whereas neurotrophic genes were down-regulated, neurotoxic genes were up-regulated. Representative genes Lcn2 and chitinase-3-like protein 1 were markedly up-regulated in astrocytes from primary culture and intact transgenic rats. Furthermore, synthetic chitinase-3-like protein 1 induced neuron death in a dose-dependent manner. Our results suggest that TDP-43 pathogenesis is associated with the simultaneous induction of multiple neurotoxic genes in astrocytes, which may synergistically produce adverse effects on neuronal survival and contribute to non-cell-autonomous neuron death. Restricted expression of pathogenic TDP-43 in astrocytes causes non-cell-autonomous motor neuron death in transgenic rats. As revealed by microarray assay, pathogenic TDP-43 in astrocytes preferentially altered expression of the genes encoding secretory proteins. Whereas neurotrophic genes were down-regulated, neurotoxic genes were up-regulated. Therefore, TDP-43 pathogenesis is associated with simultaneous induction of neurotoxic genes and repression of neurotrophic genes in astrocytes.

Ondansetron can enhance cisplatin-induced nephrotoxicity via inhibition of multiple toxin and extrusion proteins (MATEs)

The nephrotoxicity limits the clinical application of cisplatin. Human organic cation transporter 2 (OCT2) and multidrug and toxin extrusion proteins (MATEs) work in concert in the elimination of cationic drugs such as cisplatin from the kidney. We hypothesized that co-administration of ondansetron would have an effect on cisplatin nephrotoxicity by altering the function of cisplatin transporters. The inhibitory potencies of ondansetron on metformin accumulation mediated by OCT2 and MATEs were determined in the stable HEK-293 cells expressing these transporters. The effects of ondansetron on drug disposition in vivo were examined by conducting the pharmacokinetics of metformin, a classical substrate for OCTs and MATEs, in wild-type and Mate1-/- mice. The nephrotoxicity was assessed in the wild-type and Mate1-/- mice received cisplatin with and without ondansetron. Both MATEs, including human MATE1, human MATE2-K, and mouse Mate1, and OCT2 (human and mouse) were subject to ondansetron inhibition, with much greater potencies by ondansetron on MATEs. Ondansetron significantly increased tissue accumulation and pharmacokinetic exposure of metformin in wild-type but not in Mate1-/- mice. Moreover, ondansetron treatment significantly enhanced renal accumulation of cisplatin and cisplatin-induced nephrotoxicity which were indicated by increased levels of biochemical and molecular biomarkers and more severe pathohistological changes in mice. Similar increases in nephrotoxicity were caused by genetic deficiency of MATE function in mice. Therefore, the potent inhibition of MATEs by ondansetron enhances the nephrotoxicity associated with cisplatin treatment in mice. Potential nephrotoxic effects of combining the chemotherapeutic cisplatin and the antiemetic 5-hydroxytryptamine-3 (5-HT3) receptor antagonists, such as ondansetron, should be investigated in patients.