Recent studies have demonstrated that upon encountering a pathogenic stimulus, robust metabolic rewiring of immune cells occurs. A switch away from oxidative phosphorylation to glycolysis, even in the presence of sufficient amounts of oxygen (akin the Warburg effect), is typically observed in activated innate and adaptive immune cells and is thought to accommodate adequate inflammatory responses. However, whether the Warburg effect is a general phenomenon applicable in human monocytes exposed to different pathogenic stimuli is unknown. Our results using human monocytes from healthy donors demonstrate that the Warburg effect only holds true for TLR4 activated cells. Although activation of other TLRs leads to an increase in glycolysis, no reduction or even an enhancement in oxidative phosphorylation is observed. Moreover, specific metabolic rewiring occurs in TLR4 vs. TLR2 stimulated cells characterized by altered gene expression profiles of pathways related to metabolism, changes in spare respiratory capacity of the cells and differential regulation of mitochondrial enzyme activity. Similarly, results from ex vivo and in vivo studies demonstrate metabolic rewiring of immune cells that is highly dependent on the type of pathogenic stimulus. Although the Warburg effect is observed in human monocytes after TLR4 activation, we propose that this typical metabolic response is not applicable to other inflammatory signalling routes including TLR2 in human monocytes. Instead, each pathogenic stimulus and subsequently activated inflammatory signalling cascade induces specific metabolic rewiring of the immune cell to accommodate an appropriate response.
Microbial stimulation of different Toll-like receptor signalling pathways induces diverse metabolic programmes in human monocytes.
Specimen part, Treatment, Subject
View SamplesPeroxisome proliferator-activated receptor alpha (PPAR) is a key regulator of hepatic fat oxidation that serves as an energy source during starvation. Vanin-1 has been described as a putative PPAR target gene in liver, but its function in hepatic lipid metabolism is unknown. We investigated the regulation of vanin-1, and total vanin activity, by PPAR in mice and humans. Furthermore, the function of vanin-1 in the development of hepatic steatosis in response to starvation was examined in Vnn1 deficient mice, and in rats treated with an inhibitor of vanin activity. Liver microarray analyses reveals that Vnn1 is the most prominently regulated gene after modulation of PPAR activity. In addition, activation of mouse PPAR regulates hepatic- and plasma vanin activity. In humans, consistent with regulation by PPAR, plasma vanin activity increases in all subjects after prolonged fasting, as well as after treatment with the PPAR agonist fenofibrate. In mice, absence of vanin-1 exacerbates the fasting-induced increase in hepatic triglyceride levels. Similarly, inhibition of vanin activity in rats induces accumulation of hepatic triglycerides upon fasting. Microarray analysis reveal that the absence of vanin-1 associates with gene sets involved in liver steatosis, and reduces pathways involved in oxidative stress and inflammation. We show that hepatic vanin-1 is under extremely sensitive regulation by PPAR and that plasma vanin activity could serve as a readout of changes in PPAR activity in human subjects. In addition, our data propose a role for vanin-1 in regulation of hepatic TG levels during fasting.
PPAR-alpha dependent regulation of vanin-1 mediates hepatic lipid metabolism.
Sex, Specimen part, Time
View SamplesObesity induces macrophages to drive inflammation in adipose tissue, a crucial step towards the development of type 2 diabetes. The tricarboxylic acid (TCA) cycle intermediate succinate is released from cells under metabolic stress and has recently emerged as a metabolic signal induced by proinflammatory stimuli. We therefore investigated whether succinate receptor 1 (SUCNR1) could play a role in the development of adipose tissue inflammation and type 2 diabetes. Succinate levels were determined in human plasma samples from individuals with type 2 diabetes and non-diabetic participants. Succinate release from adipose tissue explants was studied. Sucnr1 -/- and wild-type (WT) littermate mice were fed a high-fat diet (HFD) or low-fat diet (LFD) for 16 weeks. Serum metabolic variables, adipose tissue inflammation, macrophage migration and glucose tolerance were determined. We show that hypoxia and hyperglycaemia independently drive the release of succinate from mouse adipose tissue (17-fold and up to 18-fold, respectively) and that plasma levels of succinate were higher in participants with type 2 diabetes compared with non-diabetic individuals (+53%; p < 0.01). Sucnr1 -/- mice had significantly reduced numbers of macrophages (0.56 0.07 vs 0.92 0.15 F4/80 cells/adipocytes, p < 0.05) and crown-like structures (0.06 0.02 vs 0.14 0.02, CLS/adipocytes p < 0.01) in adipose tissue and significantly improved glucose tolerance (p < 0.001) compared with WT mice fed an HFD, despite similarly increased body weights. Consistently, macrophages from Sucnr1 -/- mice showed reduced chemotaxis towards medium collected from apoptotic and hypoxic adipocytes (-59%; p < 0.05). Our results reveal that activation of SUCNR1 in macrophages is important for both infiltration and inflammation of adipose tissue in obesity, and suggest that SUCNR1 is a promising therapeutic target in obesity-induced type 2 diabetes.
SUCNR1-mediated chemotaxis of macrophages aggravates obesity-induced inflammation and diabetes.
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View SamplesCytokines of the IL-1 family are important modulators of obesity-induced inflammation and the development of systemic insulin resistance. Here, we report that IL-37, a newly-described antiinflammatory member of the IL-1 family, affects obesity-induced inflammation and insulin resistance. IL-37 transgenic mice (IL-37tg) did not develop an obese phenotype in response to a high-fat diet (HFD). Unlike WT mice, IL-37tg mice exhibited reduced numbers of adipose tissue macrophages and preserved glucose tolerance and insulin sensitivity after 16 weeks of HFD. A short-term HFD intervention revealed that the IL-37-mediated improvement in glucose tolerance is independent of bodyweight. IL-37tg mice manifested a beneficial metabolic profile with higher circulating levels of the anti-inflammatory adipokine adiponectin. In vitro treatment of differentiating adipocytes with recombinant IL-37 reduced adipogenesis. The beneficial effects of recombinant IL-37 involved activation of AMPK signaling. In humans, steady-state IL-37 adipose tissue mRNA levels were positively correlated with insulin sensitivity, lower adipose tissue levels of leptin and a lower inflammatory status of the adipose tissue. These findings reveal IL-37 as an important anti-inflammatory modulator during obesity-induced inflammation and insulin resistance in both mice and humans and suggest that IL-37 is a potential target for the treatment of obesity-induced insulin resistance and type 2 diabetes.
IL-37 protects against obesity-induced inflammation and insulin resistance.
Sex, Specimen part
View SamplesBacterial lipopolysaccharide(LPS) dramatically activates macrophages. So far, dozen of papers indicated that many proinflammatory molecules are transcriptionaly regulated during response. Despite of this,translational regulation is not fully elucidated especially in a comprehensive fashion. In this series, we investigated expression profiles of translation active (polysome) inactive (free mRNP) mRNAs of a typical mouse macrophage cell line, J774.1. Moreover, we also measured total cellular RNA level as a reference.
Genome-wide identification and characterization of transcripts translationally regulated by bacterial lipopolysaccharide in macrophage-like J774.1 cells.
Specimen part
View SamplesWhile blood transcriptional profiling has improved diagnosis and understanding of disease pathogenesis of adult tuberculosis (TB), no studies applying gene expression profiling of children with TB have been described so far. In this study, we have compared whole blood gene expression in childhood TB patients, as well as in healthy latently infected (LTBI) and uninfected (HC) children in a cohort of Warao Amerindians in the Delta Amacuro in Venezuela. We identified a 116-gene signature set by means of random forest analysis that showed an average prediction error of 11% for TB vs. LTBI and for TB vs. LTBI vs. HC in our dataset. Furthermore, a minimal set of only 9 genes showed a significant predictive value for all previously published adult studies using whole blood gene expression, with average prediction errors between 17% and 23%. Additionally, a minimal gene set of 42 genes with a comparable predictive value to the 116-gene set in both our dataset and the previously published literature cohorts for the comparsion of TB vs. LTBI vs. HC was identified. In order to identify a robust representative gene set that would hold stand among different ethnic populations, we selected ten genes that were highly discriminative between TB, LTBI and HC in all literature datasets as well as in our dataset. Functional annotation of these ten genes highlights a possible role for genes involved in calcium signaling and calcium metabolism as biomarkers for active TB. These ten genes were validated by quantitative real-time polymerase chain reaction in an additional cohort of 54 Warao Amerindian children with LTBI, HC and non-TB pneumonia. Decision tree analysis indicated that five of the ten genes were sufficient to diagnose 78% of the TB cases correctly with 100% specificity. We conclude that our data justify the further exploration of our signature set as biomarkers to diagnose childhood TB. Furthermore, as the identification of different biomarkers in ethnically distinct cohorts is apparent, it is important to cross-validate newly identified markers in all available cohorts.
A predictive signature gene set for discriminating active from latent tuberculosis in Warao Amerindian children.
Sex, Age
View SamplesHow organ size and form are controlled during development is a major question of biology. Blood vessels have been shown to be essential for early development of the liver and pancreas, and are fundamental to normal and pathological tissue growth. Here we report that non-nutritional signals from blood vessels surprisingly act to restrain pancreas growth. Elimination of endothelial cells increases the size of embryonic pancreatic buds. Conversely, VEGF-induced hypervascularization decreases pancreas size. The growth phenotype results from vascular restriction of pancreatic tip cell formation, lateral branching and differentiation of the pancreatic epithelium into endocrine and acinar cells. The effects are seen both in vivo and ex vivo, indicating a perfusion-independent mechanism. Thus the vasculature controls pancreas morphogenesis and growth by reducing branching and differentiation of primitive epithelial cells.
Blood vessels restrain pancreas branching, differentiation and growth.
Specimen part
View SamplesTo obtain insight into the genetic basis of the increase of functional activity of memory B cells over time, we compared the gene expression profiles of day 7 and day 40 NP-specific/IgG1 memory B cells, GC B cells and plasma cells in immunized WT mice and nave B cells, before and after activation in vitro.
Distinct cellular pathways select germline-encoded and somatically mutated antibodies into immunological memory.
Sex, Age, Specimen part
View SamplesBcl6 germline deletion causes a prominent inflammatory disease, owing to over-expression of Th2 cytokines, and affects the properties of B cells prior to immunization. Therefore we established the B cell-specific Bcl6 deletion mice and analyze the gene expression of naive B cells under physiological conditions.
Distinct cellular pathways select germline-encoded and somatically mutated antibodies into immunological memory.
Sex, Age
View SamplesThe CCR4-NOT complex, bearing poly(A) deadenylation activity, is a highly conserved regulator that is involved in biological control; however its action mechanisms and physiological targets remain unclear. Using genetic deletion of the CNOT3 subunit of this complex in early B cell progenitors, we show that CNOT3 plays a critical role in pro- to pre-B cell transition. CNOT3 participated in controlling germline transcription, compaction of the immunoglobulin heavy chain (Igh) locus, and Igh rearrangement, and in destabilizing tumor suppressor p53 mRNA. Moreover, by genetic ablation of p53 or introduction of pre-rearranged Igh transgene, the B cell developmental defect in the Cnot3 knockout background could be partly rescued, suggesting that CCR4-NOT complex exerts critical control in B cell differentiation processes by co-utilizing transcriptional and post-transcriptional mechanisms. Overall design: Pro-B cells mRNA profiles of Mb1(cre/+) and Cnot3(fl/fl)Mb1(cre/+) mice were generated by deep sequencing using Illumina HiSeq 1500
CNOT3 contributes to early B cell development by controlling Igh rearrangement and p53 mRNA stability.
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