TPL-2 Inhibits IFN-β Expression via an ERK1/2-TCF-FOS Axis in TLR4-Stimulated Macrophages

TPL-2 activation of ERK1/2 regulates gene expression in TLR-stimulated macrophages.

TPL-2 regulates transcription via ERK1/2 phosphorylation of ternary complex factors.

TPL-2 inhibits Ifnb1 transcription via ternary complex factor–induced Fos mRNA expression.

TPL-2 kinase plays an important role in innate immunity, activating ERK1/2 MAPKs in myeloid cells following TLR stimulation. We investigated how TPL-2 controls transcription in TLR4-stimulated mouse macrophages. TPL-2 activation of ERK1/2 regulated expression of genes encoding transcription factors, cytokines, chemokines, and signaling regulators. Bioinformatics analysis of gene clusters most rapidly induced by TPL-2 suggested that their transcription was mediated by the ternary complex factor (TCF) and FOS transcription factor families. Consistently, TPL-2 induced ERK1/2 phosphorylation of the ELK1 TCF and the expression of TCF target genes. Furthermore, transcriptomic analysis of TCF-deficient macrophages demonstrated that TCFs mediate approximately half of the transcriptional output of TPL-2 signaling, partially via induced expression of secondary transcription factors. TPL-2 signaling and TCFs were required for maximal TLR4-induced FOS expression. Comparative analysis of the transcriptome of TLR4-stimulated Fos^−/− macrophages indicated that TPL-2 regulated a significant fraction of genes by controlling FOS expression levels. A key function of this ERK1/2-TCF-FOS pathway was to mediate TPL-2 suppression of type I IFN signaling, which is essential for host resistance against intracellular bacterial infection.

Precision Measurement of the β Asymmetry in Spin-Polarized ^{37}K Decay

Using Triumf's neutral atom trap, Trinat, for nuclear β decay, we have measured the β asymmetry with respect to the initial nuclear spin in ^{37}K to be A_{β}=-0.5707(13)_{syst}(13)_{stat}(5)_{pol}, a 0.3% measurement. This is the best relative accuracy of any β-asymmetry measurement in a nucleus or the neutron, and is in agreement with the standard model prediction -0.5706(7). We compare constraints on physics beyond the standard model with other β-decay measurements, and improve the value of V_{ud} measured in this mirror nucleus by a factor of 4.

Abstract 42: Control of Macrophage Cholesterol Efflux and Atherogenesis by the Noncoding RNA MeXis

The ligand-dependent nuclear receptor LXR regulates the expression of genes involved in responses to excess cholesterol including Abca1. Macrophage-specific cholesterol efflux driven by Abca1 has been causally linked to the prevention and reversal of heart disease, but therapeutic strategies for targeting efflux pathways in macrophages have been elusive. Here, we define a novel regulatory axis controlling macrophage responses to cholesterol overload. We identify the lncRNA MeXis as an amplifier of LXR-dependent Abca1 gene transcription in macrophages. MeXis interacts with and guides the promoter binding of nuclear receptor transcriptional coactivators. Loss of MeXis in murine immune cells has a marked impact on chromosome architecture at the Abca1 locus, impairs cellular responses to cholesterol overload, and accelerates the development of atherosclerosis. Our findings identify MeXis as a transcriptional gatekeeper that modifies the actions of LXR in lipid-dependent control of macrophage gene expression. It is conceivable that therapeutic approaches that enhance MeXis activity might augment reverse cholesterol transport and reduce foam cell formation.

Observation of Quantum-Limited Spin Transport in Strongly Interacting Two-Dimensional Fermi Gases

We measure the transport properties of two-dimensional ultracold Fermi gases during transverse demagnetization in a magnetic field gradient. Using a phase-coherent spin-echo sequence, we are able to distinguish bare spin diffusion from the Leggett-Rice effect, in which demagnetization is slowed by the precession of a spin current around the local magnetization. When the two-dimensional scattering length is tuned to be comparable to the inverse Fermi wave vector k_{F}^{-1}, we find that the bare transverse spin diffusivity reaches a minimum of 1.7(6)ℏ/m, where m is the bare particle mass. The rate of demagnetization is also reflected in the growth rate of the s-wave contact, observed using time-resolved spectroscopy. The contact rises to 0.28(3)k_{F}^{2} per particle, which quantifies how scaling symmetry is broken by near-resonant interactions, unlike in unitary three-dimensional systems. Our observations support the conjecture that, in systems with strong scattering, the local relaxation rate is bounded from above by k_{B}T/ℏ.

Emergence of function from coordinated cells in a tissue

This work presents a mathematical study of tissue dynamics. We combine within-cell genome dynamics and diffusion between cells, so that the synthesis of the two gives rise to the emergence of function, akin to establishing "tissue homeostasis." We introduce two concepts, monotonicity and a weak version of hardwiring. These together are sufficient for global convergence of the tissue dynamics.

Physiologic stress molecules activate an acute phase response and enhance macrophage antimicrobial activity to Mycobacterium leprae (INM3P.411)

Leprosy is a disease caused by the pathogen Mycobacterium leprae (mLEP). Patients can present with the progressive, lepromatous form of the disease or the self-limited, tuberculoid form of the disease. Physiologic stress is thought to inhibit host defense mediated by adrenergic catecholamines and neuroendocrine glucocorticoids. We hypothesize that acute treatment with adrenergic agents or glucocorticoids would inhibit in vitro macrophage mediated antimicrobial activity. Human monocyte-derived macrophages or mouse bone marrow-derived macrophages were treated with the adrenergic agonist metaproterenol hemisulfate (MPH, 1μM) or the glucocorticoid dexamethasone (Dex, 100nM) for two hours followed by LPS (100ng/ml) or mLEP (MOI 5). RNASeq was performed at various time points or an mLEP viability measurement was performed at 24 hours following infection. Unexpectedly, when compared to vehicle (DMSO), pretreatment with MPH resulted in greatly enhanced antimicrobial activity against mLEP, similar to interferon-γ pretreatment, whereas Dex resulted in a more modest induction of antimicrobial activity. Both Dex and MPH did not reduce the expression of the antimicrobial peptide cathelicidin, but did induce a dramatic increase in expression of genes involved in the acute phase response. Our findings suggest that molecules involved in the physiological stress response may be acutely beneficial during initial encounter with mLEP.

Global regulation of Toll-like receptor 4-induced inflammatory gene networks by physiologic stress signals in macrophages (INM7P.356)

Physiologic stress mediated through adrenergic (catecholamines) and neuroendocrine (glucocorticoids) signals negatively impacts cutaneous host defense to pathogens and worsens inflammatory skin conditions such as psoriasis. Toll-like receptors (TLRs) on macrophages and other innate immune cells sense danger signals and trigger innate and adaptive immunity, but whether these stress stimuli affect similar or exclusive TLR-dependent immune pathways is unclear. We hypothesize that quantitative analysis by RNAseq will provide critical information into the mechanism by which stress affects macrophage inflammatory signaling. Using RNASeq, we find distinct regulatory profiles for β-adrenergic agonist and GC on TLR4-mediated inflammatory responses. β-adrenergic stimuli are highly selective inhibitors of a small subset of TLR4-inducible genes, inhibiting less than 15 genes by 5-fold or more (80% inhibition), showing striking selectivity. Three of these genes, Il12b, Il27, and Il6, are induced with similar kinetics and high magnitude, suggesting similar regulation of these genes. In contrast, the glucocorticoid Dexamethasone (Dex) inhibited 22 of the 283 induced genes. Importantly, Dex targeted a different subset of inflammatory genes, including Il1b, Il1a, and Ptgs2. In conclusion, we found that adrenergic and neuroendocrine stress signaling targets distinct macrophage inflammatory responses, which may cooperate to inhibit different immune pathways during a physiologic stress response.

Limiting cholesterol biosynthesis acts as a danger signal that engages STING-dependent inflammation (INM2P.349)

Pathogen invasion alters host lipid metabolism, however the mechanisms underlying this remain poorly understood. Here, we show that transcriptional repression of cholesterol and fatty acid biosynthesis is driven by TRIF-dependent danger signals. Unexpectedly, decreasing cholesterol biosynthesis induces type I interferon (IFN)-mediated inflammation in the absence of conventional danger signals, resulting in resistance to pathogens. Spontaneous induction of inflammation was traced to a reduction in cellular cholesterol levels, and normalizing cholesterol attenuated IFNb and interferon stimulated gene expression. Epistasis studies indicate that the Stimulator of Interferon Genes (STING) links cellular cholesterol balance to type I IFN-mediated inflammation. These findings reveal that perturbing cholesterol homeostasis acts as an independent “danger” signal sensed by host defense machinery, and provides mechanistic insights as to how lipid metabolism influences inflammation.

Observation of the Leggett-Rice effect in a unitary Fermi gas

We observe that the diffusive spin current in a strongly interacting degenerate Fermi gas of (40)K precesses about the local magnetization. As predicted by Leggett and Rice, precession is observed both in the Ramsey phase of a spin-echo sequence, and in the nonlinearity of the magnetization decay. At unitarity, we measure a Leggett-Rice parameter γ=1.08(9) and a bare transverse spin diffusivity D(0)(⊥)=2.3(4)ℏ/m for a normal-state gas initialized with full polarization and at one-fifth of the Fermi temperature, where m is the atomic mass. One might expect γ=0 at unitarity, where two-body scattering is purely dissipative. We observe γ→0 as temperature is increased towards the Fermi temperature, consistent with calculations that show the degenerate Fermi sea restores a nonzero γ. Tuning the scattering length a, we find that a sign change in γ occurs in the range 0<(k(F)a)(-1)≲1.3, where k(F) is the Fermi momentum. We discuss how γ reveals the effective interaction strength of the gas, such that the sign change in γ indicates a switching of branch between a repulsive and an attractive Fermi gas.

let-7 miRNAs can act through notch to regulate human gliogenesis

It is clear that neural differentiation from human pluripotent stem cells generates cells that are developmentally immature. Here, we show that the let-7 plays a functional role in the developmental decision making of human neural progenitors, controlling whether these cells make neurons or glia. Through gain- and loss-of-function studies on both tissue and pluripotent derived cells, our data show that let-7 specifically regulates decision making in this context by regulation of a key chromatin-associated protein, HMGA2. Furthermore, we provide evidence that the let-7/HMGA2 circuit acts on HES5, a NOTCH effector and well-established node that regulates fate decisions in the nervous system. These data link the let-7 circuit to NOTCH signaling and suggest that this interaction serves to regulate human developmental progression.

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let-7 miRNAs influence developmental maturity of neural progenitors

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let-7 miRNAs act through HMGA2 and NOTCH to regulate gliogenesis

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HMGA2 expression regulates access of NICD to HES5 promoter

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Induction of let-7 miRNAs can accelerate oligodendrogenesis

Selective requirement of Ikaros zinc fingers in Treg and Th17 fate decision. (P1137)

TGF-β is a common factor important for the differentiation of pro-inflammatory Th17 and anti-inflammatory inducible Treg cells. However, the precise molecular mechanisms underlying the fate decision of differentiating CD4+ T cells in the presence of TGF-β is poorly understood. Here, we show that distinctive N-terminal DNA-binding zinc fingers of Ikaros play essential roles in Treg and Th17 fate decision. Ikaros has a highly conserved DNA-binding domain near the N-terminus with four tandem zinc fingers. Zinc fingers 2 and 3 are required for stable binding to DNA, whereas fingers 1 and 4 appear to be important for differentially modulating binding properties to specific sites at target genes. Our data show that T cells lacking Ikaros zinc finger 4 but not 1 failed to differentiate into Foxp3+ Tregs upon TGF-β stimulation. Instead, TGF-β-skewed Ikaros zinc finger 4 mutant cells displayed aberrant upregulation of Th17-associated cytokines IL-17 and IL-22. IL-17 but not IL-22 upregulation is dependent on transcription factor RORγt. Aryl hydrocarbon receptor, an essential transcription factor required for IL-22 expression, was unexpectedly decreased. Together, our data uncover a novel selective requirement for Ikaros zinc fingers in the differentiation of Treg and Th17 cells and an intricate interplay among various transcription factors in programming Th17/Treg lineages. We are currently examining the role of Ikaros zinc finger 4 in infection and autoimmunity.

Contractile, but not endothelial, dysfunction in early inflammatory arthritis: a possible role for matrix metalloproteinase-9

BACKGROUND AND PURPOSE

Excess morbidity/mortality in rheumatoid arthritis (RA) is associated with increased incidence of cardiovascular disease. In this 'proof-of-concept' study, vascular function was characterized in the murine collagen-induced arthritis (mCIA) model, the benchmark choice for evaluation of the pathological processes and assessment of new therapies.

EXPERIMENTAL APPROACH

Mice in the very early stages of arthritis development [and appropriate naïve (non-immunized) age-matched controls] were used in the study. Blood pressure was measured using tail cuff plethysmography. Vascular function in rings of isolated aorta was studied with isometric tension myography. Levels of NO metabolites (NO(x)), MMP-9 protein and IL-1β in plasma and MMP-9 protein in aortic homogenates were quantified.

KEY RESULTS

Impaired vascular contractile responses in arthritis were unaffected by ex vivo inhibition of NOS (endothelial/neuronal and inducible) or COX activities. Endothelium-dependent and -independent relaxation, plasma NO(x) and blood pressure were unaffected by arthritis. Plasma and aortic homogenate MMP-9 protein levels were increased significantly in arthritis. Incubation of aortic tissues from naïve control animals with exogenous MMP-9 impaired subsequent contractile responses, mirroring that observed in arthritis. A role for IL-1β in perpetuating contractile dysfunction and increasing aortic MMP-9 was excluded.

CONCLUSIONS AND IMPLICATIONS

These data identify for the first time a relationship between early arthritis and contractile dysfunction and a possible role for MMP-9 therein, in the absence of overt endothelial dysfunction or increased NO production. As such, MMP-9 may constitute a significant target for early intervention in RA patients with a view to decreasing risk of cardiovascular disease.

Role of Ikaros in hematopoiesis and tumor suppression: Selective functions of individual zinc fingers within the DNA-binding domain of Ikaros. (42.3)

Ikaros, a C2H2 zinc finger transcription factor, is a critical regulator of hematopoiesis and tumor suppression in the lymphoid lineage. The C2H2 zinc finger is the most prevalent DNA-binding motif in mammals, with DNA-binding domains usually containing more tandem fingers than are needed for stable sequence-specific DNA recognition. To examine the reason for the frequent presence of multiple zinc fingers, and to investigate in greater depth the role of Ikaros in hematopoiesis and tumor suppression, we generated mice lacking finger 1 or finger 4 of the 4-finger DNA-binding domain of Ikaros. Each mutant strain exhibited a specific subset of the phenotypes observed with Ikaros null mice. Of particular relevance, fingers 1 and 4 contributed to distinct stages of B- and T-cell development and finger 4 was selectively required for tumor suppression in thymocytes and in a new model of BCR-ABL+ acute lymphoblastic leukemia. These results, combined with transcriptome profiling and DNA-binding analysis, reveal that different subsets of fingers within multi-finger transcription factors can modulate binding to different target sequences and regulate distinct target genes and biological functions. These novel mutant strains provide a powerful tool to elucidate Ikaros' role in hematopoiesis and tumor suppression. Furthermore, this study demonstrates that selective mutagenesis can facilitate efforts to elucidate the functions and mechanisms of action of this prevalent class of factors.

Upper gastrointestinal endoscopy performed by nurses: scope for the future?

BACKGROUND

Previous researchers have shown that non-medical endoscopists can perform lower gastrointestinal endoscopy as safely and effectively as medical staff. However, it is not known if upper gastrointestinal endoscopy performed by medical and non-medical endoscopists in clinical practice yields similar results in terms of performance, patient discomfort, and satisfaction.

AIM

To determine differences in the yield of diagnosis for significant disease during upper gastrointestinal endoscopy performed by nurse and medical endoscopists and to measure patient discomfort, satisfaction, and attitudes towards future endoscopy.

PATIENTS

This two part study included 3009 patients in a retrospective analysis and 480 in a prospective study.

METHODS

The first part of the study assessed indications for endoscopy, diagnoses, and procedures performed by medical and nurse endoscopists. In a second prospective study, 480 patients were included to determine the association between endoscopist type and sedation, patient anxiety, discomfort, satisfaction, and attitudes towards future sedation.

RESULTS

No patient refused endoscopy by either a nurse or medical endoscopist and there were no complications in either group. Nurses performed 1487 procedures and reported fewer endoscopies as "normal" than medical staff (p=0.006). Multivariate analysis showed that male sex, older age, inpatient status, dysphagia, and gastrointestinal bleeding, but not endoscopist type, were all associated with significant disease. In relation to discomfort and satisfaction, a similar proportion of patients received sedation in both groups (p=0.81). There were no differences in pre-procedure anxiety (p=0.61), discomfort during intubation (p=0.97), discomfort during examination (p=0.90), or post-procedure examination rating (p=0.79) in patients examined by medical or nurse endoscopists.

CONCLUSION

Experienced nurses perform routine diagnostic gastroscopy safely in everyday clinical practice and with as little discomfort and as much patient satisfaction as medical staff.

Epidemiology and differential diagnosis of NSAID-induced injury to the mucosa of the small intestine

Non-steroidal anti-inflammatory drugs cause small-bowel inflammation in about 60% of patients receiving these drugs long-term. The inflammation is associated with small intestinal bleeding, protein loss, ulcers and occasionally strictures. Treatment options for NSAID enteropathy include metronidazole, sulphasalazine and misoprostol, and some patients may require surgery. The diagnosis of NSAID enteropathy is not always straightforward. It is especially difficult to differentiate it from the ileitis associated with spondylarthropathy and, at times, that of Crohn's disease. An investigational algorithm is suggested for this purpose. In the last decade a number of small-bowel diseases have been identified, where none were thought to exist, because of the increasing use of enteroscopy and new sensitive tests for intestinal inflammation. Optimal treatments of these conditions are still to be studied.

The effect of gamma-linolenic acid-alpha-lipoic acid on functional deficits in the peripheral and central nervous system of streptozotocin-diabetic rats

Diabetes mellitus can lead to functional and structural deficits in both the peripheral and central nervous system. The pathogenesis of these deficits is multifactorial, probably involving, among others, microvascular dysfunction and oxidative stress. The present study examined the effects of 12 weeks of treatment with a conjugate of the essential fatty acid gamma-linolenic acid and the anti-oxidant alpha-lipoic acid (GLA-LA) on functional deficits in the peripheral and central nervous system in streptozotocin-diabetic rats. Treatment was initiated 16 weeks after diabetes induction. Sciatic nerve motor and sensory conduction velocity, brainstem auditory evoked potentials and visual evoked potentials were measured in control, untreated and GLA-LA treated diabetic rats. Also, long-term potentiation, a form of synaptic plasticity used as a model for learning and memory at the cellular level, was examined in hippocampal slices. GLA-LA treatment (50 mg/kg/day) did not reverse established deficits in nerve conduction velocity or in evoked potential latencies in diabetic rats. However, GLA-LA treatment did improve long-term potentiation in the hippocampus. It is concluded that GLA-LA, which is known to improve early deficits in peripheral nerve conduction in diabetic rats, is unable to reverse late deficits. However, the compound does reverse established deficits in long-term potentiation, suggesting that at least part of its activity is specifically directed at synaptic plasticity.

Small intestinal permeability

The noninvasive assessment of small intestinal permeability in humans is now within the capability of any routine biochemistry laboratory. There remain however, many pitfalls for the unwary when performing these tests. Importantly, it has now been shown that normal intestinal permeability relates to geographical location rather than race. Recent studies show that it may be possible to simplify the procedure even further. The main recent focus of interest in measuring intestinal permeability relates to patients with AIDS and inflammatory bowel disease, the effects of nonsteroidal anti-inflammatory drugs on the small bowel, and the use of these tests in the pediatric population and critically ill. Some groups have now started to focus their attention on the possible systemic consequences of increased intestinal permeability, whereas others have shown that increased small bowel permeability results in small intestinal inflammation that may in turn be associated with blood and protein loss.

Differential interaction of nuclear factors with the leukocyte-specific pp52 promoter in B and T cells

The leukocyte-specific, cytoskeleton-binding pp52 (LSP-1, WP-34) protein is widely expressed in multiple leukocyte lineages, including B and T lymphocytes, granulocytes, and macrophages. We previously detected a tissue-specific promoter preceding the exon encoding the N terminus of the pp52 leukocyte protein. Here we describe the functional characterization of this promoter and identification of the factors in B and T cells that regulate its activity. The pp52 promoter contains an initiator specifying the unique 5' terminus of pp52 mRNA, tandem pairs of Ets and SP1 motifs, and a lone C/EBP motif. All these motifs are essential and collectively control transcriptional activity. DNA binding studies and Ab supershift assays revealed that different combinations of factors interact with these motifs in B cells vs T cells. The Ets motifs are preferentially bound by PU-1 in B cell extracts from all stages of development, whereas a different Ets family member reacts with these motifs in T cell extracts. The C/EBP motif is bound by Ig/EBP-1 in pre-B cell and T cell extracts, but is replaced by nuclear factor-IL-6beta or a nuclear factor-IL-6beta-Ig/EBP-1 heterodimer in plasmacytoma cell extracts. Despite its reported role as a negative regulator of transcription, Ig/EBP-1 appears to exert a stimulatory effect on this promoter. These findings reveal the features controlling the pp52 promoter in B and T cells and provide the foundation for determining the regulation of this promoter in other leukocyte lineages.

Differential interaction of nuclear factors with the leukocyte-specific pp52 promoter in B and T cells

The leukocyte-specific, cytoskeleton-binding pp52 (LSP-1, WP-34) protein is widely expressed in multiple leukocyte lineages, including B and T lymphocytes, granulocytes, and macrophages. We previously detected a tissue-specific promoter preceding the exon encoding the N terminus of the pp52 leukocyte protein. Here we describe the functional characterization of this promoter and identification of the factors in B and T cells that regulate its activity. The pp52 promoter contains an initiator specifying the unique 5' terminus of pp52 mRNA, tandem pairs of Ets and SP1 motifs, and a lone C/EBP motif. All these motifs are essential and collectively control transcriptional activity. DNA binding studies and Ab supershift assays revealed that different combinations of factors interact with these motifs in B cells vs T cells. The Ets motifs are preferentially bound by PU-1 in B cell extracts from all stages of development, whereas a different Ets family member reacts with these motifs in T cell extracts. The C/EBP motif is bound by Ig/EBP-1 in pre-B cell and T cell extracts, but is replaced by nuclear factor-IL-6beta or a nuclear factor-IL-6beta-Ig/EBP-1 heterodimer in plasmacytoma cell extracts. Despite its reported role as a negative regulator of transcription, Ig/EBP-1 appears to exert a stimulatory effect on this promoter. These findings reveal the features controlling the pp52 promoter in B and T cells and provide the foundation for determining the regulation of this promoter in other leukocyte lineages.

Long term effects on activity in female mice following exposure to urine from lactating mothers

Infant female mice exposed to the urine of lactating donors prior to weaning subsequently showed, when adult, activity levels in keeping with those of the donors that provided the urine. Mice with low levels of activity provided urine which acted on target mice to restrict their movements and standing behaviour when tested in an open arena. The urine of high active donors enhanced activity as compared with the urine from donors of mid range activity levels. Housing in large groups reduced the activity of the recipients exposed to urine from the low active donors. The males were more active than the females but the exposure of males to the urine of the donors had no effect on their activity levels.