[Show abstract][Hide abstract] ABSTRACT: Tyrosine kinase 2 (TYK2) is a Janus kinase (JAK) that is crucially involved in inflammation, carcinogenesis and defense against infection. The cytotoxic activity of natural killer (NK) cells in TYK2-deficient (Tyk2−/−) mice is severely reduced, although the underlying mechanisms are largely unknown. Using Tyk2−/− mice and mice expressing a kinase-inactive version of TYK2 (Tyk2K923E), we show that NK cell function is partly independent of the enzymatic activity of TYK2. Tyk2−/− and Tyk2K923E NK cells develop normally in the bone marrow, but the maturation of splenic Tyk2−/− NK cells (and to a lesser extent of Tyk2K923E NK cells) is impaired. In contrast, the production of interferon γ (IFNγ) in response to interleukin 12 (IL-12) or to stimulation through NK cell-activating receptors strictly depends on the presence of enzymatically active TYK2. The cytotoxic activity of Tyk2K923E NK cells against a range of target cells in vitro is higher than that of Tyk2−/− NK cells. Consistently, Tyk2K923E mice control the growth of NK cell-targeted tumors significantly better than TYK2-deficient mice, showing the physiological relevance of the finding. Inhibitors of TYK2's kinase activity are being developed for the treatment of inflammatory diseases and cancers, but their effects on tumor immune surveillance have not been investigated. Our finding that TYK2 has kinase-independent functions in vivo suggests that such inhibitors will leave NK cell mediated tumor surveillance largely intact and that they will be suitable for use in cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: Trypanosomosis is a serious cause of reduction in productivity of cattle in tsetse-fly infested areas. Baoule and other local Taurine cattle breeds in Burkina Faso are trypanotolerant. Zebuine cattle, which are also kept there are susceptible to trypanosomosis but bigger in body size. Farmers have continuously been intercrossing Baoule and Zebu animals to increase production and disease tolerance. The aim of this study was to compare levels of zebuine and taurine admixture in genomic regions potentially involved in trypanotolerance with background admixture of composites to identify differences in allelic frequencies of tolerant and non-tolerant animals. The study was conducted on 214 animals (90 Baoule, 90 Zebu, and 34 composites), genotyped with 25 microsatellites across the genome and with 155 SNPs in 23 candidate regions. Degrees of admixture of composites were analyzed for microsatellite and SNP data separately. Average Baoule admixture based on microsatellites across the genomes of the Baoule-Zebu composites was 0.31, which was smaller than the average Baoule admixture in the trypanosomosis candidate regions of 0.37 (P = 0.15). Fixation index F ST measured in the overall genome based on microsatellites or with SNPs from candidate regions indicates strong differentiation between breeds. Nine out of 23 regions had F ST ≥ 0.20 calculated from haplotypes or individual SNPs. The levels of admixture were significantly different from background admixture, as revealed by microsatellite data, for six out of the nine regions. Five out of the six regions showed an excess of Baoule ancestry. Information about best levels of breed composition would be useful for future breeding ctivities, aiming at trypanotolerant animals with higher productive capacity.
Frontiers in Genetics 05/2015; 6. DOI:10.3389/fgene.2015.00137
[Show abstract][Hide abstract] ABSTRACT: Myeloid cells lacking STAT3 promote antitumor responses of NK and T cells but it is unknown if this crosstalk affects development of autochthonous tumors. We deleted STAT3 in murine myeloid cells (STAT3(Δm)) and examined the effect on the development of autochthonous colorectal cancers (CRCs). Formation of Azoxymethane/Dextransulfate (AOM/DSS)-induced CRCs was strongly suppressed in STAT3(Δm) mice. Gene expression profiling showed strong activation of T cells in the stroma of STAT3(Δm) CRCs. Moreover, STAT3(Δm) host mice were better able to control the growth of transplanted MC38 colorectal tumor cells which are known to be killed in a T cell-dependent manner. These data suggest that myeloid cells lacking STAT3 control formation of CRCs mainly via cross activation of T cells. Interestingly, the few CRCs that formed in STAT3(Δm) mice displayed enhanced stromalization but appeared normal in size indicating that they have acquired ways to escape enhanced tumor surveillance. We found that CRCs in STAT3(Δm) mice consistently activate STAT3 signaling which is implicated in immune evasion and might be a target to prevent tumor relapse.
[Show abstract][Hide abstract] ABSTRACT: Adult stem cells (SCs) retain the capacity of self-renewal and differentiation to generate multiple differentiated cell types (Barker et al., 2007). Thus, these adult SCs are utilized to functionally regenerate damaged tissues or reverse organ failure (Yui et al., 2012). However, SCs that are deregulated during inflammation, infection, or tissue regeneration may turn into invasive cancer SCs (CSCs) (Beachy et al., 2004). Accordingly, tight spatial-temporal regulation of adult SC behaviors may confer injury resistance, tissue regeneration, or tumor suppression, whereas SC deregulation may cause tumor initiation and/or recurrence (Merlos-Suárez et al., 2011). However, the lack of molecular markers that reflect the fine modulation of SC homeostatic response to injury or regeneration significantly hinders the development of regenerative medicine and cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: Bacterial pathogens are known for their wide range of strategies to specifically adapt to host environments and infection sites. An in-depth understanding of these adaptation mechanisms is crucial for the development of effective therapeutics and new prevention measures. In this study, we assessed the suitability of Fourier Transform Infrared (FTIR) spectroscopy for monitoring metabolic adaptations of the bacterial pathogen Listeria monocytogenes to specific host genotypes and for exploring the potential of FTIR spectroscopy to gain novel insights into the host-pathogen interaction. Three different mouse genotypes, showing different susceptibility to L. monocytogenes infections, were challenged with L. monocytogenes and re-isolated bacteria were subjected to FTIR spectroscopy. The bacteria from mice with different survival characteristics showed distinct IR spectral patterns, reflecting specific changes in the backbone conformation and the hydrogen-bonding pattern of the protein secondary structure in the bacterial cell. Coupling FTIR spectroscopy with chemometrics allowed us to link bacterial metabolic fingerprints with host infection susceptibility and to decipher longtime memory effects of the host on the bacteria. After prolonged cultivation of host-passaged bacteria under standard laboratory conditions, the host's imprint on bacterial metabolism vanished, which suggests a revertible metabolic adaptation of bacteria to host environment and loss of host environment triggered memory effects over time. In summary, our work demonstrates the potential and power of FTIR spectroscopy to be used as a fast, simple and highly discriminatory tool to investigate the mechanism of bacterial host adaptation on a macromolar and metabolic level.
PLoS ONE 12/2014; 9(12):e115959. DOI:10.1371/journal.pone.0115959 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Severe sepsis and septic shock are leading causes of morbidity and mortality worldwide. Infection-associated inflammation promotes the development and progression of adverse outcomes in sepsis. The effects of heterodimeric IL-27 (p28/EBI3) have been implicated in the natural course of sepsis, whereas the molecular mechanisms underlying the regulation of gene expression and release of IL-27 in sepsis are poorly understood. We studied the events regulating the p28 subunit of IL-27 in endotoxic shock and polymicrobial sepsis following cecal ligation and puncture. Neutralizing Abs to IL-27(p28) improved survival rates, restricted cytokine release, and reduced bacterial burden in C57BL/6 mice during sepsis. Genetic disruption of IL-27 signaling enhanced the respiratory burst of macrophages. Experiments using splenectomized mice or treatment with clodronate liposomes suggested that macrophages in the spleen may be a significant source of IL-27(p28) during sepsis. In cultures of TLR4-activated macrophages, the frequency of F4/80(+)CD11b(+)IL-27(p28)(+) cells was reduced by the addition of IL-10. IL-10 antagonized both MyD88-dependent and TRIF-dependent release of IL-27(p28). Genetic deletion of STAT3 in Tie2-Cre/STAT3flox macrophages completely interrupted the inhibition of IL-27(p28) by IL-10 after TLR4 activation. In contrast, IL-10 remained fully active to suppress IL-27(p28) with deletion of SOCS3 in Tie2-Cre/SOCS3flox macrophages. Blockade of IL-10R by Ab or genetic deficiency of IL-10 resulted in 3-5-fold higher concentrations of IL-27(p28) in endotoxic shock and polymicrobial sepsis. Our studies identify IL-10 as a critical suppressing factor for IL-27(p28) production during infection-associated inflammation. These findings may be helpful for a beneficial manipulation of adverse IL-27(p28) release during sepsis.
The Journal of Immunology 10/2014; 193(11). DOI:10.4049/jimmunol.1302280 · 4.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The members of the STAT family of transcription factors modulate the development and function of NK cells. NK cell-mediated tumor surveillance is particularly important in the body's defense against hematological malignancies such as leukemia. STAT3 inhibitors are currently being developed, although their potential effects on NK cells are not clear. We have investigated the function of STAT3 in NK cells with Stat3(Δ/Δ)Ncr1-iCreTg mice, whose NK cells lack STAT3. In the absence of STAT3, NK cells develop normally and in normal numbers but display alterations in the kinetics of IFN-γ production. We report that STAT3 directly binds the IFN-γ promoter. In various in vivo models of hematological diseases loss of STAT3 in NK cells enhances tumor surveillance. The reduced tumor burden is paralleled by increased expression of the activating receptor DNAM-1 and the lytic enzymes perforin and granzyme B. Our findings imply that STAT3 inhibitors will stimulate the cytolytic activity of NK cells against leukemia, thereby providing an additional therapeutic benefit.
[Show abstract][Hide abstract] ABSTRACT: Unlabelled:
Growth hormone (GH) resistance has been associated with liver cirrhosis in humans but its contribution to the disease remains controversial. In order to elucidate whether GH resistance plays a causal role in the establishment and development of liver fibrosis, or rather represents a major consequence thereof, we challenged mice lacking the GH receptor gene (Ghr(-/-), a model for GH resistance) by crossing them with Mdr2 knockout mice (Mdr2(-/-)), a mouse model of inflammatory cholestasis and liver fibrosis. Ghr(-/-);Mdr2(-/-) mice showed elevated serum markers associated with liver damage and cholestasis, extensive bile duct proliferation, and increased collagen deposition relative to Mdr2(-/-) mice, thus suggesting a more severe liver fibrosis phenotype. Additionally, Ghr(-/-);Mdr2(-/-) mice had a pronounced down-regulation of hepatoprotective genes Hnf6, Egfr, and Igf-1, and significantly increased levels of reactive oxygen species (ROS) and apoptosis in hepatocytes, compared to control mice. Moreover, single knockout mice (Ghr(-/-)) fed with a diet containing 1% cholic acid displayed an increase in hepatocyte ROS production, hepatocyte apoptosis, and bile infarcts compared to their wild-type littermates, indicating that loss of Ghr renders hepatocytes more susceptible to toxic bile acid accumulation. Surprisingly, and despite their severe fibrotic phenotype, Ghr(-/-);Mdr2(-/-) mice displayed a significant decrease in tumor incidence compared to Mdr2(-/-) mice, indicating that loss of Ghr signaling may slow the progression from fibrosis/cirrhosis to cancer in the liver.
GH resistance dramatically exacerbates liver fibrosis in a mouse model of inflammatory cholestasis, therefore suggesting that GH resistance plays a causal role in the disease and provides a novel target for the development of liver fibrosis treatments.
[Show abstract][Hide abstract] ABSTRACT: The contribution of the innate immune system to inflammatory bowel disease (IBD) is under intensive investigation. Research in animal models has demonstrated that type I interferons (IFN-Is) protect from IBD. In contrast, studies of patients with IBD have produced conflicting results concerning the therapeutic potential of IFN-Is. Here we present data suggesting that IFN-Is play dual roles as regulators of intestinal inflammation in dextran sodium sulfate (DSS)-treated C57BL/6 mice. Though IFN-Is reduced acute intestinal damage and the abundance of colitis-associated intestinal bacteria caused by treatment with a high dose of DSS, they also inhibited the resolution of inflammation after DSS treatment. IFN-Is played an anti-inflammatory role by suppressing the release of IL-1β from the colon MHC class II+ cells. Consistently, IL-1 receptor blockade reduced the severity of inflammation in IFN-I receptor-deficient mice and myeloid cell-restricted ablation of the IFN-I receptor was detrimental. The pro-inflammatory role of IFN-Is during recovery from DSS treatment was caused by IFN-I-dependent cell apoptosis as well as an increase in chemokine production and infiltrating inflammatory monocytes and neutrophils. Thus, IFN-Is play opposing roles in specific phases of intestinal injury and inflammation, which may be important for guiding treatment strategies in patients.This article is protected by copyright. All rights reserved
European Journal of Immunology 09/2014; 44(9). DOI:10.1002/eji.201344401 · 4.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The transcription factor STAT1 is essential for interferon (IFN)-mediated immunity in humans and mice. STAT1 function is tightly
regulated, and both loss- and gain-of-function mutations result in severe immune diseases. The two alternatively spliced isoforms,
STAT1α and STAT1β, differ with regard to a C-terminal transactivation domain, which is absent in STAT1β. STAT1β is considered
to be transcriptionally inactive and to be a competitive inhibitor of STAT1α. To investigate the functions of the STAT1 isoforms
in vivo, we generated mice deficient for either STAT1α or STAT1β. As expected, the functions of STAT1α and STAT1β in IFN-α/β- and
IFN-λ-dependent antiviral activity are largely redundant. In contrast to the current dogma, however, we found that STAT1β
is transcriptionally active in response to IFN-γ. In the absence of STAT1α, STAT1β shows more prolonged IFN-γ-induced phosphorylation
and promoter binding. Both isoforms mediate protective, IFN-γ-dependent immunity against the bacterium Listeria monocytogenes, although with remarkably different efficiencies. Our data shed new light on the potential contributions of the individual
STAT1 isoforms to STAT1-dependent immune responses. Knowledge of STAT1β's function will help fine-tune diagnostic approaches
and help design more specific strategies to interfere with STAT1 activity.
[Show abstract][Hide abstract] ABSTRACT: Tyrosine kinase 2 (TYK2) has a pivotal role in immunity to infection and tumor surveillance. It is associated with several cytokine receptor chains including type I interferon (IFN) receptor 1 (IFNAR1), interleukin- (IL-) 12 receptor beta 1 (IL-12Rb1) and IL-10R2. We have generated a mouse with a conditional Tyk2 null allele and proved integrity of the conditional Tyk2 locus. TYK2 was successfully removed by the use of ubiquitous and tissue-specific Cre-expressing mouse strains. Myeloid TYK2 was found to critically contribute to the defense against murine cytomegalovirus. Ubiquitous TYK2 ablation severely impaired tumor immunosurveillance, while deletion in myeloid, dendritic or T cells alone showed no effect. The conditional Tyk2 mouse strain will be instrumental to further dissect TYK2 functions in infection, inflammation and cancer.
Transgenic Research 04/2014; 23(3). DOI:10.1007/s11248-014-9795-y · 2.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to test the hypothesis that gene expression and release of IL-27 may be modulated by Tyk2. Macrophages derived from the peritoneum or bone marrow of C57BL/10SnJ (WT) mice produced abundant amounts of IL-27(p28) following TLR4 activation by LPS. In contrast, production of IL-27(p28), but not EBI3, was reduced by ∼50% in TLR4-activated macrophages derived from mice with genetic deficiency of Tyk2 compared with WT macrophages. Frequencies of IL-27(p28)+F4/80+CD11b+ cells were lower in TLR4-activated macrophages derived from Tyk2-/- mice. Mechanistically, Tyk2-/- resulted in disruption of a type I IFN-dependent mechanism for production of IL-27(p28), which was induced by type I IFNs, and release of IL-27 was defective in macrophages from IFN-β-/- and IFNAR1-/- mice. In contrast, Tyk2 was not required to mediate the effects of IL-27 on target gene expression in CD4(+) T cells. In vivo, we observed that Tyk2-/- mice have improved survival following endotoxic shock or polymicrobial sepsis induced by CLP. Plasma levels of IL-27(p28) during endotoxic shock or polymicrobial sepsis were markedly reduced in Tyk2-/- mice compared with WT mice. Disruption of IL-27 signaling using IL-27RA-/- mice was protective against sepsis-associated mortality. These data suggest that Tyk2 may mediate adverse outcomes of SIRS by promoting the production of IL-27. In conclusion, this report identifies Tyk2 as a prerequisite factor in the molecular networks that are involved in generation of IL-27.
[Show abstract][Hide abstract] ABSTRACT: Considerable amount of effort has been undertaken to identify genes that account for myeloid lineage commitment and development. However, currently available non-invasive mouse models utilize myeloid-specific reporters that are significantly expressed in hematopoietic stem cells as well as lymphoid compartments. Here, we describe a myeloid-specific marker that is not shared by any other lineage. We show that lactotransferrin mRNA is expressed by Gr-1+/CD11b+ cells in the bone marrow, as opposed to HSCs or any peripheral cell population. To follow the progeny of lactotransferrin-expressing bone marrow cells, we generated a mouse model in which a reporter gene is irreversibly activated from the lactotransferrin-promoter. We found that lactotransferrin-reporter labels a majority of neutrophils, monocytes, macrophages and distinct subtypes of dendritic cells, while excluding T-, B-, NK-cells, iKDC, pDCs, erythrocytes and eosinophils. Lactotransferrin-reporter- bone marrow cells retain lymphoid, erythroid and long-term repopulating potential, while lactotransferrin-reporter+ bone marrow cells confer only myeloid, but no lymphoid potential. We conclude that lactotransferrin represents a late stage differentiation marker of neutrophils, macrophages and distinct subtypes of dendritic cells.
[Show abstract][Hide abstract] ABSTRACT: Signal transducer and activator of transcription (STAT) 1 is a key player in interferon (IFN) signaling, essential in mediating host defense against viruses and other pathogens. STAT1 levels are tightly regulated and loss- or gain-of-function mutations in mice and men lead to severe diseases. We have generated a doxycycline (dox) -inducible, FLAG-tagged Stat1 expression system in mice lacking endogenous STAT1 (i.e. Stat1(ind) mice). We show that STAT1 expression depends on the time and dose of dox treatment in primary cells and a variety of organs isolated from Stat1(ind) mice. In bone marrow-derived macrophages, a fraction of the amount of STAT1 present in WT cells is sufficient for full expression of IFN-induced genes. Dox-induced STAT1 established protection against virus infections in primary cells and mice. The availability of the Stat1(ind) mouse model will enable an examination of the consequences of variable amounts of STAT1. The model will also permit the study of STAT1 dose-dependent and reversible functions as well as of STAT1's contributions to the development, progression and resolution of disease.
PLoS ONE 01/2014; 9(1):e86608. DOI:10.1371/journal.pone.0086608 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although alterations in gut microbiota composition during acute colitis have been repeatedly observed, associated functional changes and the recovery from dysbiosis received little attention. In this study, we investigated structure and function of the gut microbiota during acute inflammation and recovery in a dextran sodium sulfate (DSS)-colitis mouse model using metatranscriptomics, bacterial 16S rRNA gene amplicon sequencing and monitoring of selected host markers. Parallel to an increase of host markers of inflammation during acute colitis, we observed relative abundance shifts and alterations in phylotype composition of the dominant bacterial orders Clostridiales and Bacteroidales, and an increase of the low abundant Enterobacteriales, Deferribacterales, Verrucomicrobiales and Erysipelotrichales. During recovery, the microbiota began to resume, but did not reach its original composition until the end of the experiment. Microbial gene expression was more resilient to disturbance, with pre-perturbation-type transcript profiles appearing quickly after acute colitis. The decrease of Clostridiales during inflammation correlated with a reduction of transcripts related to butyrate formation, suggesting a disturbance in host-microbe signalling and mucosal nutrient provision. The impact of acute inflammation on the Clostridiales was also characterized by a significant downregulation of their flagellin-encoding genes. In contrast, the abundance of members of the Bacteroidales increased along with an increase in transcripts related to mucin degradation. We propose that acute inflammation triggered a selective reaction of the immune system against flagella of commensals and temporarily altered murine microbiota composition and functions relevant for the host. Despite changes in specific interactions, the host-microbiota homeostasis revealed a remarkable ability for recovery.The ISME Journal advance online publication, 9 January 2014; doi:10.1038/ismej.2013.223.
The ISME Journal 01/2014; 8(5). DOI:10.1038/ismej.2013.223 · 9.30 Impact Factor