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1.
Physiol Rep ; 8(9): e14441, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32385968

RESUMO

C57BL/6 (BL6) and Balb/c mice exhibit prototypical Th1- and Th2-dominant immune predispositions, respectively. Iron is a proinflammatory metal ion; however, limited information is documented on the differences in iron homeostasis between BL6 and Balb/c strains. The objective of this study was to investigate the extent to which strain-level differences in these mice dictates the regulation of iron homeostasis during physiologic and inflammatory conditions. At basal levels, Balb/c mice displayed significantly higher levels of iron in systemic circulation and tissue compared to BL6 mice. Moreover, Balb/c mice had greater iron absorption as indicated by higher gene expressions of duodenal DcytB, DMT1, Fpn, SFT, and Heph. Similarly, hepatic Tf, TfR1, TfR2, and DMT1 expressions were augmented in Balb/c mice. Interestingly, there was no change in hepatic Hamp expression between the two strains, suggesting that the disparity in their maintenance of iron is independent of hepcidin. Additionally, the basal levels of intracellular labile iron pool in Balb/c intestinal epithelial cells, and bone marrow-derived macrophages and neutrophils, were higher compared to BL6 mice. When mice were challenged with lipopolysaccharide, the acute inflammatory response in BL6 mice was more pronounced than in Balb/c mice, as indicated by the more rapid development of hypoferremia and upregulation of serum IL-6 and TNF-α levels in BL6 mice. In conclusion, this study underscores that iron homeostasis is distinct between BL6 and Balb/c strains under both physiologic and inflammatory conditions.

2.
Gut Microbes ; : 1-15, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32223398

RESUMO

Owing to their health benefits, dietary fermentable fibers, such as refined inulin, are increasingly fortified in processed foods to enhance their nutritional value. However, we previously demonstrated that when inulin was fed to Toll-like receptor 5 deficient (T5KO) mice susceptible to dysbiosis, a subset of them developed cholestasis and subsequently liver cancer in a gut microbiota-dependent manner. Therefore, we hypothesized that clearance of bacterial taxa, and thereby gut metabolites, involved in the onset and progression to liver cancer could abate the disease in these mice. Such a reshaping of microbiota by vancomycin treatment was sufficient to halt the development of liver cancer in inulin-fed T5KO mice; however, this intervention did not remedy disease penetrance for cholestatic liver injury and its sequelae, including hyperbilirubinemia, hypolipidemia, cholemia and liver fibrosis. Selective depletion of gut bacterial communities was observed in vancomycin-treated mice, including Gram-positive Lachnospiraceae and Ruminococcaceae belonging to the phylum Firmicutes, Bifidobacteria of the phylum Actinobacteria, which ferment fibers, and Clostridium cluster XIVa, which produce secondary bile acids. Lack of liver cancer in vancomycin-treated mice strongly correlated with the substantial loss of secondary bile acids in circulation. Although cholemia was unabated by vancomycin, the composition of serum bile acids shifted toward an abundance of hydrophilic primary bile acids, denoted by the increase in conjugated-to-unconjugated bile acid ratio. Taken together, the present study suggests that microbiotal regulation of bile acid metabolism is one of the critical mediators of fermentable fiber-induced liver cancer in dysbiotic mice.

3.
Physiol Genomics ; 52(5): 217-221, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32275178
4.
Cell Mol Gastroenterol Hepatol ; 9(2): 313-333, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31593782

RESUMO

BACKGROUND & AIMS: Consumption of a low-fiber, high-fat, Western-style diet (WSD) induces adiposity and adipose inflammation characterized by increases in the M1:M2 macrophage ratio and proinflammatory cytokine expression, both of which contribute to WSD-induced metabolic syndrome. WSD-induced adipose inflammation might result from endoplasmic reticulum stress in lipid-overloaded adipocytes and/or dissemination of gut bacterial products, resulting in activation of innate immune signaling. Hence, we aimed to investigate the role of the gut microbiota, and its detection by innate immune signaling pathways, in WSD-induced adipose inflammation. METHODS: Mice were fed grain-based chow or a WSD for 8 weeks, assessed metabolically, and intestinal and adipose tissue were analyzed by flow cytometry and quantitative reverse transcription polymerase chain reaction. Microbiota was ablated via antibiotics and use of gnotobiotic mice that completely lacked microbiota (germ-free mice) or had a low-complexity microbiota (altered Schaedler flora). Innate immune signaling was ablated by genetic deletion of Toll-like receptor signaling adaptor myeloid differentiation primary response 88. RESULTS: Ablation of microbiota via antibiotic, germ-free, or altered Schaedler flora approaches did not significantly impact WSD-induced adiposity, yet dramatically reduced WSD-induced adipose inflammation as assessed by macrophage populations and cytokine expression. Microbiota ablation also prevented colonic neutrophil and CD103- dendritic cell infiltration. Such reduced indices of inflammation correlated with protection against WSD-induced dysglycemia, hypercholesterolemia, and liver dysfunction. Genetic deletion of myeloid differentiation primary response 88 also prevented WSD-induced adipose inflammation. CONCLUSIONS: These results indicate that adipose inflammation, and some aspects of metabolic syndrome, are not purely a consequence of diet-induced adiposity per se but, rather, may require disturbance of intestine-microbiota interactions and subsequent activation of innate immunity.

5.
Sci Signal ; 12(598)2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31506384

RESUMO

Inflammation alters bone marrow hematopoiesis to favor the production of innate immune effector cells at the expense of lymphoid cells and erythrocytes. Furthermore, proinflammatory cytokines inhibit steady-state erythropoiesis, which leads to the development of anemia in diseases with chronic inflammation. Acute anemia or hypoxic stress induces stress erythropoiesis, which generates a wave of new erythrocytes to maintain erythroid homeostasis until steady-state erythropoiesis can resume. Although hypoxia-dependent signaling is a key component of stress erythropoiesis, we found that inflammation also induced stress erythropoiesis in the absence of hypoxia. Using a mouse model of sterile inflammation, we demonstrated that signaling through Toll-like receptors (TLRs) paradoxically increased the phagocytosis of erythrocytes (erythrophagocytosis) by macrophages in the spleen, which enabled expression of the heme-responsive gene encoding the transcription factor SPI-C. Increased amounts of SPI-C coupled with TLR signaling promoted the expression of Gdf15 and Bmp4, both of which encode ligands that initiate the expansion of stress erythroid progenitors (SEPs) in the spleen. Furthermore, despite their inhibition of steady-state erythropoiesis in the bone marrow, the proinflammatory cytokines TNF-α and IL-1ß promoted the expansion and differentiation of SEPs in the spleen. These data suggest that inflammatory signals induce stress erythropoiesis to maintain erythroid homeostasis when inflammation inhibits steady-state erythropoiesis.

6.
Biochem Pharmacol ; 168: 71-81, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31228465

RESUMO

Iron is essential for many biological functions, including being a cofactor for enzymes involved in cell proliferation. In line, it has been shown that cancer cells can perturb their iron metabolism towards retaining an abundant iron supply for growth and survival. Accordingly, it has been suggested that iron deprivation through the use of iron chelators could attenuate cancer progression. While they have exhibited anti-tumor properties in vitro, the current therapeutic iron chelators are inadequate due to their low efficacy. Therefore, we investigated whether the bacterial catecholate-type siderophore, enterobactin (Ent), could be used as a potent anti-cancer agent given its strong iron chelation property. We demonstrated that iron-free Ent can exert cytotoxic effects specifically towards monocyte-related tumor cell lines (RAW264.7 and J774A.1), but not primary cells, i.e. bone marrow-derived macrophages (BMDMs), through two mechanisms. First, we observed that RAW264.7 and J774A.1 cells preserve a bountiful intracellular labile iron pool (LIP), whose homeostasis can be disrupted by Ent. This may be due, in part, to the lower levels of lipocalin 2 (Lcn2; an Ent-binding protein) in these cell lines, whereas the higher levels of Lcn2 in BMDMs could prevent Ent from hindering their LIP. Secondly, we observed that Ent could dose-dependently impede reactive oxygen species (ROS) generation in the mitochondria. Such disruption in LIP balance and mitochondrial function may in turn promote cancer cell apoptosis. Collectively, our study highlights Ent as an anti-cancer siderophore, which can be exploited as an unique agent for cancer therapy.

7.
Artigo em Inglês | MEDLINE | ID: mdl-30838179

RESUMO

The host immune system is constantly exposed to diverse microbial ligands, including flagellin (FliC; a ligand for TLR5 and NLRC4) and lipopolysaccharide (LPS; a ligand for TLR4), which could induce immune tolerance to subsequent exposure. Herein, we investigated the extent to which FliC induces self-tolerance in vivo and the role of adaptive immunity in mediating such effect. Mice pre-treated with FliC displayed attenuated serum keratinocyte-derived chemokine (KC), interleukin (IL)-6 and IL-18 responses to secondary challenge of FliC. A negative correlation was observed between high anti-FliC titer and reduced KC, IL-6, and IL-18 responses upon FliC re-challenge in WT mice, but not Rag1KO mice, suggesting that adaptive immunity could tolerize TLR5 and NLRC4. However, administration of LPS during FliC pre-treatment impaired the generation of anti-FliC antibodies and resulted in a partial loss of self-tolerance to FliC re-challenge. These findings may be relevant in the context of bacterial infection, as we observed that anti-FliC response are protective against systemic infection by Salmonella typhimurium. Taken together, our study delineates a distinct co-operative and reciprocal interaction between the innate and adaptive arms of immunity in modulating their responses to a bacterial protein.


Assuntos
Imunidade Adaptativa , Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Flagelina/imunologia , Tolerância Imunológica , Imunidade Inata , Receptor 5 Toll-Like/metabolismo , Animais , Camundongos , Camundongos Knockout , Salmonella typhimurium/imunologia
8.
Mucosal Immunol ; 12(3): 761-771, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30710097

RESUMO

Peptidyl arginine deiminase-4 (PAD4) is indispensable for generation of neutrophil extracellular traps (NETs), which can provide antimicrobial effects during host innate immune response; however, the role of PAD4 against gastrointestinal infection is largely unknown. Herein, we challenged PAD4-deficient (Pad4-/-) mice and wild-type (WT) littermates with Citrobacter rodentium (CR), and investigated bacteria clearance and gut pathology. Luminal colonization of CR in Pad4-/- mice peaked between 11-14 days post-infection, whereas WT mice suppressed the infection by 14 days. We demonstrated that Pad4-/- mice were unable to form NETs, whereas WT mice showed increased NETs formation in the colon during infection. Pad4-/- mice showed aggravated CR-associated inflammation as indicated by elevated systemic and colonic pro-inflammatory markers. Histological analysis revealed that transmissible colonic hyperplasia, goblet cell depletion, and apoptotic cell death were more pronounced in the colon of CR-infected Pad4-/- mice. Treating WT mice with deoxyribonuclease I, which can disrupt NETs generation, recapitulated the exacerbated CR infection and gut pathology associated with the loss of PAD4. Administration of the PAD4 inhibitor, Cl-amidine also aggravated CR infection, but to a lesser extent. Taken together, our findings highlight the importance of PAD4 in the mucosal clearance of CR and in resolving gut-associated inflammation.


Assuntos
Citrobacter rodentium/fisiologia , Colo/patologia , Infecções por Enterobacteriaceae/imunologia , Armadilhas Extracelulares/metabolismo , Hidrolases/metabolismo , Inflamação/imunologia , Intestinos/imunologia , Neutrófilos/imunologia , Animais , Carga Bacteriana , Desoxirribonuclease I/administração & dosagem , Hidrolases/genética , Imunidade Inata , Intestinos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout
9.
Gut ; 68(10): 1801-1812, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30670576

RESUMO

OBJECTIVE: Diets rich in fermentable fibres provide an array of health benefits; however, many patients with IBD report poor tolerance to fermentable fibre-rich foods. Intervention studies with dietary fibres in murine models of colonic inflammation have yielded conflicting results on whether fibres ameliorate or exacerbate IBD. Herein, we examined how replacing the insoluble fibre, cellulose, with the fermentable fibres, inulin or pectin, impacted murine colitis resulting from immune dysregulation via inhibition of interleukin (IL)-10 signalling and/or innate immune deficiency (Tlr5KO). DESIGN: Mice were fed with diet containing either cellulose, inulin or pectin and subjected to weekly injections of an IL-10 receptor (αIL-10R) neutralising antibody. Colitis development was examined by serological, biochemical, histological and immunological parameters. RESULTS: Inulin potentiated the severity of αIL10R-induced colitis, while pectin ameliorated the disease. Such exacerbation of colitis following inulin feeding was associated with enrichment of butyrate-producing bacteria and elevated levels of caecal butyrate. Blockade of butyrate production by either metronidazole or hops ß-acids ameliorated colitis severity in inulin-fed mice, whereas augmenting caecal butyrate via tributyrin increased colitis severity in cellulose containing diet-fed mice. Elevated butyrate levels were associated with increased IL-1ß activity, while inhibition of the NOD-like receptor protein 3 by genetic, pharmacologic or dietary means markedly reduced colitis. CONCLUSION: These results not only support the notion that fermentable fibres have the potential to ameliorate colitis but also caution that, in some contexts, prebiotic fibres can lead to gut dysbiosis and surfeit colonic butyrate that might exacerbate IBD.


Assuntos
Colite/metabolismo , Fibras na Dieta/metabolismo , Microbioma Gastrointestinal/fisiologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Doença Aguda , Animais , Colite/dietoterapia , Colite/microbiologia , Modelos Animais de Doenças , Fermentação , Masculino , Camundongos , Camundongos Endogâmicos NOD
10.
J Innate Immun ; 11(3): 249-262, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30605903

RESUMO

Iron is necessary for the survival of almost all aerobic organisms. In the mammalian host, iron is a required cofactor for the assembly of functional iron-sulfur (Fe-S) cluster proteins, heme-binding proteins and ribonucleotide reductases that regulate various functions, including heme synthesis, oxygen transport and DNA synthesis. However, the bioavailability of iron is low due to its insolubility under aerobic conditions. Moreover, the host coordinates a nutritional immune response to restrict the accessibility of iron against potential pathogens. To counter nutritional immunity, most commensal and pathogenic bacteria synthesize and secrete small iron chelators termed siderophores. Siderophores have potent affinity for iron, which allows them to seize the essential metal from the host iron-binding proteins. To safeguard against iron thievery, the host relies upon the innate immune protein, lipocalin 2 (Lcn2), which could sequester catecholate-type siderophores and thus impede bacterial growth. However, certain bacteria are capable of outmaneuvering the host by either producing "stealth" siderophores or by expressing competitive antagonists that bind Lcn2 in lieu of siderophores. In this review, we summarize the mechanisms underlying the complex iron tug-of-war between host and bacteria with an emphasis on how host innate immunity responds to siderophores.

11.
Gut Microbes ; 10(3): 412-423, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30449241

RESUMO

Enterobactin (Ent), a prototypical bacterial siderophore known for its unparalleled affinity for iron, is widely conserved among members of the Enterobacteriaceae family of Gram-negative bacteria. In this study, we demonstrated that, aside from mediating iron acquisition, Ent also dampened the macrophages (MΦs) antimicrobial responses against intracellular infection by Salmonella enterica serovar Typhimurium. Accordingly, the loss of Ent expression (ΔentB) in Salmonella demoted their survivability against MΦs. Addition of exogenous Ent not only rescued the survival of ΔentB Salmonella, but also augmented WT Salmonella to better withstand the microbicidal activity of MΦs. The protection conferred to WT Salmonella was observed only when Ent was administered as iron-free, thus indicating the requirement of iron chelation in this context. In contrast, the exogenous iron-bound Ent retained its ability to promote the survival of ΔentB Salmonella, albeit modestly. Assessment on MΦs labile iron pool (LIP) revealed that iron-free Ent is able to permeate into MΦs, chelate the intracellular LIP, and regulate the expression of several key iron-regulatory proteins, i.e., divalent metal transporter 1, ferroportin, and hepcidin. Chelation of iron by Ent was also observed to promote the MΦs towards M2 polarization. Collectively, our findings demonstrated that Ent not only facilitates bacterial iron uptake but also disrupts MΦs iron homeostasis and M1/M2 polarization to safeguard intracellular bacteria against the anti-bacterial effects of their host.


Assuntos
Enterobactina/metabolismo , Interações Hospedeiro-Patógeno , Macrófagos/microbiologia , Salmonella typhimurium/fisiologia , Sideróforos/metabolismo , Animais , Proteínas de Bactérias/genética , Diferenciação Celular/imunologia , Enterobactina/genética , Enterobactina/farmacologia , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Homeostase , Ferro/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Viabilidade Microbiana , Mutação , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Sideróforos/genética , Sideróforos/farmacologia
12.
Cell Rep ; 25(3): 677-689.e4, 2018 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-30332647

RESUMO

Dietary salt reduction and exercise are lifestyle modifications for salt-sensitive hypertensives. While exercise has prominent metabolic effects, salt has an adverse effect on metabolic syndrome, of which hypertension is a hallmark. We hypothesized that dietary salt impacts metabolism in a salt-sensitive model of hypertension. An untargeted metabolomic approach demonstrates lower circulating levels of the ketone body, beta-hydroxybutyrate (ßOHB), in high salt-fed hypertensive rats. Despite the high salt intake, specific rescue of ßOHB levels by nutritional supplementation of its precursor, 1,3-butanediol, attenuates hypertension and protects kidney function. This beneficial effect of ßOHB was likely independent of gut-microbiotal and Th17-mediated effects of salt and instead facilitated by ßOHB inhibiting the renal Nlrp3 inflammasome. The juxtaposed effects of dietary salt and exercise on salt-sensitive hypertension, which decrease and increase ßOHB respectively, indicate that nutritional supplementation of a precursor of ßOHB provides a similar benefit to salt-sensitive hypertension as exercise.


Assuntos
Ácido 3-Hidroxibutírico/farmacologia , Microbioma Gastrointestinal/efeitos dos fármacos , Hipertensão/prevenção & controle , Inflamassomos/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Cloreto de Sódio na Dieta/toxicidade , Ácido 3-Hidroxibutírico/administração & dosagem , Animais , Pressão Sanguínea , Aromatizantes/toxicidade , Hipertensão/induzido quimicamente , Hipertensão/metabolismo , Inflamassomos/imunologia , Inflamassomos/metabolismo , Masculino , Ratos , Ratos Endogâmicos Dahl
13.
Cell ; 175(3): 679-694.e22, 2018 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-30340040

RESUMO

Dietary soluble fibers are fermented by gut bacteria into short-chain fatty acids (SCFA), which are considered broadly health-promoting. Accordingly, consumption of such fibers ameliorates metabolic syndrome. However, incorporating soluble fiber inulin, but not insoluble fiber, into a compositionally defined diet, induced icteric hepatocellular carcinoma (HCC). Such HCC was microbiota-dependent and observed in multiple strains of dysbiotic mice but not in germ-free nor antibiotics-treated mice. Furthermore, consumption of an inulin-enriched high-fat diet induced both dysbiosis and HCC in wild-type (WT) mice. Inulin-induced HCC progressed via early onset of cholestasis, hepatocyte death, followed by neutrophilic inflammation in liver. Pharmacologic inhibition of fermentation or depletion of fermenting bacteria markedly reduced intestinal SCFA and prevented HCC. Intervening with cholestyramine to prevent reabsorption of bile acids also conferred protection against such HCC. Thus, its benefits notwithstanding, enrichment of foods with fermentable fiber should be approached with great caution as it may increase risk of HCC.


Assuntos
Carcinoma Hepatocelular/etiologia , Colestase/complicações , Fibras na Dieta/metabolismo , Disbiose/complicações , Fermentação , Microbioma Gastrointestinal , Neoplasias Hepáticas/etiologia , Animais , Carcinoma Hepatocelular/microbiologia , Linhagem Celular Tumoral , Colestase/microbiologia , Dieta Hiperlipídica/efeitos adversos , Disbiose/microbiologia , Inulina/efeitos adversos , Neoplasias Hepáticas/microbiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL
14.
J Nutr Biochem ; 62: 28-34, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30218980

RESUMO

Iron deficiency is routinely treated with oral or systemic iron supplements, which are highly reactive and could induce oxidative stress via augmenting the activity of proinflammatory enzyme myeloperoxidase (MPO). To investigate the extent to which MPO is involved in iron-induced toxicity, acute (24 h) iron toxicity was induced by intraperitoneal administration of FeSO4 (25 mg/kg body weight) to MPO-deficient (MpoKO) mice and their wild-type (WT) littermates. Acute iron toxicity was also assessed in WT mice pretreated with an MPO inhibitor, 4-aminobenzoic acid hydrazide. Systemic iron administration up-regulated circulating MPO and neutrophil elastase and elevated systemic inflammatory and organ damage markers in WT mice. However, genetic deletion of MPO or its inhibition significantly reduced iron-induced organ damage and systemic inflammatory responses. In contrast to the acute model, 8 weeks of 2% carbonyl iron diet feeding to WT mice did not change the levels of circulating MPO and neutrophil elastase but promoted their accumulation in the liver. Even though both MpoKO and WT mice displayed similar levels of diet-induced hyperferremia, MpoKO mice showed significantly reduced inflammatory response and oxidative stress than the WT mice. In addition, WT bone-marrow-derived neutrophils (BMDN) generated more reactive oxygen species than MPO-deficient BMDN upon iron stimulation. Altogether, genetic deficiency or pharmacologic inhibition of MPO substantially attenuated acute and chronic iron-induced toxicity. Our results suggest that targeting MPO during iron supplementation is a promising approach to reduce iron-induced toxicity/side effects in vulnerable population.


Assuntos
Ferro na Dieta/efeitos adversos , Erros Inatos do Metabolismo/metabolismo , Peroxidase/genética , Compostos de Anilina/farmacologia , Animais , Sobrecarga de Ferro/tratamento farmacológico , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Peroxidase/antagonistas & inibidores , Peroxidase/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Testes de Toxicidade Aguda
15.
JNCI Cancer Spectr ; 2(4): pky083, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30815627

RESUMO

Background: Circulating cell-free DNA (cfDNA) is a proposed latent biomarker for several cancers, including liver cancer. Deoxyribonucleases (DNases) facilitate the timely and efficient degradation of cfDNA, leading us to hypothesize that DNase I and/or II might be a more sensitive early biomarker than cfDNA. To test this hypothesis, a study was conducted in a large, prospective cohort. Methods: A nested case-control study (224 liver cancer case patients and 224 matched control subjects) was conducted in a cohort of Finnish male smokers, followed from baseline (1985-1988) to 2014. The associations among DNase I activity, cfDNA, and the risk of liver cancer were assessed using multivariable-adjusted conditional logistic regression. Results: DNase I activity, whether measured as radius (mm) or as units per milliliter, was statistically significantly associated with increased risk of liver cancer (P trend <.01). DNase I activity in the highest quartile was associated with a greater than threefold risk of developing liver cancer (DNase I activity radius >2.7 mm, hazard ratio [HR] = 3.03, 95% confidence interval [CI] = 1.59 to 5.77; DNase I activity >2.72 units/mL, HR = 3.30, 95% CI = 1.64 to 6.65). The strength of this association was not substantially altered by exclusion of cases diagnosed within the first five years of follow-up or those with hepatitis C virus (HCV) infection. In contrast, cfDNA and DNase II was not statistically significantly associated with risk of liver cancer. Conclusions: DNase I activity was a superior latent biomarker of liver cancer than cfDNA. These findings advance the goal of developing a means to detect liver cancer years well before the development of clinical manifestations.

16.
Annu Rev Nutr ; 37: 103-130, 2017 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-28628361

RESUMO

Lipocalin 2 (Lcn2), an innate immune protein, has emerged as a critical iron regulatory protein during physiological and inflammatory conditions. As a bacteriostatic factor, Lcn2 obstructs the siderophore iron-acquiring strategy of bacteria and thus inhibits bacterial growth. As part of host nutritional immunity, Lcn2 facilitates systemic, cellular, and mucosal hypoferremia during inflammation, in addition to stabilizing the siderophore-bound labile iron pool. In this review, we summarize recent advances in understanding the interaction between Lcn2 and iron, and its effects in various inflammatory diseases. Lcn2 exerts mostly a protective role in infectious and inflammatory bowel diseases, whereas both beneficial and detrimental functions have been documented in neurodegenerative diseases, metabolic syndrome, renal disorders, skin disorders, and cancer. Further animal and clinical studies are necessary to unveil the multifaceted roles of Lcn2 in iron dysregulation during inflammation and to explore its therapeutic potential for treating inflammatory diseases.


Assuntos
Homeostase , Inflamação , Ferro/metabolismo , Lipocalina-2/metabolismo , Animais , Bactérias/efeitos dos fármacos , Humanos , Lipocalina-2/imunologia
17.
Inflamm Bowel Dis ; 23(7): 1120-1132, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28445245

RESUMO

BACKGROUND: Lipocalin-2 (Lcn2) is a multifunctional innate immune protein that exhibits antimicrobial activity by the sequestration of bacterial siderophores, regulates iron homeostasis, and augments cellular tolerance to oxidative stress. Studies in the murine model of colitis have demonstrated that Lcn2 deficiency exacerbates colitogenesis; however, the therapeutic potential of Lcn2 supplementation has yet to be elucidated. In light of its potential mucoprotective functions, we, herein, investigated whether expression of Lcn2 in the probiotic bacterium can be exploited to alleviate experimental colitis. METHODS: Murine Lcn2 was cloned into the pT1NX plasmid and transformed into Lactococcus lactis to generate L. lactis-expressing Lcn2 (Lactis-Lcn2) or the empty plasmid (Lactis-Con). Lactis-Lcn2 was characterized by immunoblot and enzyme-linked immunosorbent assay and tested for its antimicrobial efficacy on Escherichia coli. The capacity of Lactis-Lcn2 and Lactis-Con to withstand adverse conditions was tested using in vitro viability assays. Dextran sodium sulfate colitis model was used to investigate the colonization ability and therapeutic potential of Lactis-Lcn2 and Lactis-Con. RESULTS: Lcn2 derived from Lactis-Lcn2 inhibited the growth of E. coli and reduced the bioactivity of enterobactin (E. coli-derived siderophore) in vitro. Lactis-Lcn2 displayed enhanced tolerance to adverse pH, high concentration of bile acids, and oxidative stress in vitro and survived better in the inflamed gut than Lactis-Con. Consistent with these features, Lactis-Lcn2 displayed better mucoprotection against intestinal inflammation than Lactis-Con when administered into mice with dextran sulfate sodium-induced acute colitis. CONCLUSIONS: Our findings suggest that Lcn2 expression can be exploited to enhance the survivability of probiotic bacteria during inflammation, which could further improve its efficacy to treat experimental colitis.


Assuntos
Colite/prevenção & controle , Modelos Animais de Doenças , Inflamação/prevenção & controle , Intestinos/efeitos dos fármacos , Lactococcus lactis/fisiologia , Lipocalina-2/metabolismo , Substâncias Protetoras/farmacologia , Animais , Colite/induzido quimicamente , Colite/metabolismo , Sulfato de Dextrana/toxicidade , Expressão Ectópica do Gene , Feminino , Inflamação/metabolismo , Mucosa Intestinal/metabolismo , Intestinos/microbiologia , Lipocalina-2/genética , Camundongos , Camundongos Endogâmicos C57BL
18.
J Immunol ; 198(11): 4293-4303, 2017 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-28432145

RESUMO

Neutrophils are the primary immune cells that respond to inflammation and combat microbial transgression. To thrive, the bacteria residing in their mammalian host have to withstand the antibactericidal responses of neutrophils. We report that enterobactin (Ent), a catecholate siderophore expressed by Escherichia coli, inhibited PMA-induced generation of reactive oxygen species (ROS) and neutrophil extracellular traps (NETs) in mouse and human neutrophils. Ent also impaired the degranulation of primary granules and inhibited phagocytosis and bactericidal activity of neutrophils, without affecting their migration and chemotaxis. Molecular analysis revealed that Ent can chelate intracellular labile iron that is required for neutrophil oxidative responses. Other siderophores (pyoverdine, ferrichrome, deferoxamine) likewise inhibited ROS and NETs in neutrophils, thus indicating that the chelation of iron may largely explain their inhibitory effects. To counter iron theft by Ent, neutrophils rely on the siderophore-binding protein lipocalin 2 (Lcn2) in a "tug-of-war" for iron. The inhibition of neutrophil ROS and NETs by Ent was augmented in Lcn2-deficient neutrophils compared with wild-type neutrophils but was rescued by the exogenous addition of recombinant Lcn2. Taken together, our findings illustrate the novel concept that microbial siderophore's iron-scavenging property may serve as an antiradical defense system that neutralizes the immune functions of neutrophils.


Assuntos
Enterobactina/metabolismo , Enterobactina/farmacologia , Armadilhas Extracelulares/imunologia , Neutrófilos/efeitos dos fármacos , Neutrófilos/fisiologia , Sideróforos/farmacologia , Animais , Quimiotaxia/efeitos dos fármacos , Enterobactina/química , Escherichia coli/química , Armadilhas Extracelulares/efeitos dos fármacos , Humanos , Ferro/metabolismo , Lipocalina-2/genética , Lipocalina-2/metabolismo , Lipocalina-2/farmacologia , Camundongos , Neutrófilos/imunologia , Neutrófilos/patologia , Fagocitose/efeitos dos fármacos , Sideróforos/metabolismo , Acetato de Tetradecanoilforbol/farmacologia
19.
Data Brief ; 11: 588-592, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28349107

RESUMO

The data herein is related to the research article entitled "Microbiota-inducible Innate Immune, Siderophore Binding Protein Lipocalin 2 is Critical for Intestinal Homeostasis" (Singh et al., 2016) [1] where we have demonstrated that C57BL/6 Lipocalin 2 deficient mice (Lcn2KO) developed chronic colitis upon anti-interleukin-10 receptor (αIL-10R) monoclonal antibody administration. In the present article, we evaluated the susceptibility of BALB/c Lcn2KO mice and their WT littermates to the αIL-10R neutralization-induced chronic colitis. Our data showed that αIL-10R mAb-treated BALB/c Lcn2KO mice exhibited severe chronic colitis (i.e., splenomegaly, colomegaly, colonic pathology, and incidence of rectal prolapse) when compared to WT mice.

20.
J Nutr Biochem ; 41: 25-33, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27951517

RESUMO

Mammalian siderophores are believed to play a critical role in maintaining iron homeostasis. However, the properties and functions of mammalian siderophores have not been fully clarified. In this study, we have employed Chrome Azurol S (CAS) assay which is a well-established method for bacterial siderophores study, to detect and quantify mammalian siderophores in urine samples. Our study demonstrates that siderophores in urine can be altered by diet, gut microbiota and inflammation. C57BL/6 mice, fed on plant-based chow diets which contain numerous phytochemicals, have more siderophores in the urine compared to those fed on purified diets. Urinary siderophores were up-regulated in iron overload conditions, but not altered by other tested nutrients status. Further, germ-free mice displayed 50% reduced urinary siderophores, in comparison to conventional mice, indicating microbiota biotransformation is critical in generating or stimulating host metabolism to create more siderophores. Altered urinary siderophores levels during inflammation suggest that host health conditions influence systemic siderophores level. This is the first report to measure urinary siderophores as a whole, describing how siderophores levels are modulated under different physiological conditions. We believe that our study opens up a new field in mammalian siderophores research and the technique we used in a novel manner has the potential to be applied to clinical purpose.


Assuntos
Anemia Ferropriva/urina , Colite/urina , Dieta/efeitos adversos , Microbioma Gastrointestinal , Sobrecarga de Ferro/urina , Sideróforos/urina , Deficiência de Vitamina A/urina , Anemia Ferropriva/etiologia , Anemia Ferropriva/imunologia , Anemia Ferropriva/microbiologia , Animais , Biomarcadores/sangue , Biomarcadores/urina , Colite/induzido quimicamente , Colite/imunologia , Colite/microbiologia , Cruzamentos Genéticos , Dieta Hiperlipídica/efeitos adversos , Feminino , Vida Livre de Germes , Proteína da Hemocromatose/genética , Proteína da Hemocromatose/metabolismo , Sobrecarga de Ferro/etiologia , Sobrecarga de Ferro/imunologia , Sobrecarga de Ferro/microbiologia , Lipocalina-2/genética , Lipocalina-2/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Salmonelose Animal/imunologia , Salmonelose Animal/microbiologia , Salmonelose Animal/urina , Selênio/deficiência , Selênio/imunologia , Selênio/envenenamento , Deficiência de Vitamina A/etiologia , Deficiência de Vitamina A/imunologia , Deficiência de Vitamina A/microbiologia
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