Lipopolysaccharide induces intestinal glucocorticoid synthesis in a TNFalpha-dependent manner

Stringent control of immune responses in the intestinal mucosa is critical for the maintenance of immune homeostasis and prevention of tissue damage, such as observed during inflammatory bowel disease. Intestinal epithelial cells, primarily thought to form a simple physical barrier, critically regulate intestinal immune cell functions by producing immunoregulatory glucocorticoids on T-cell activation. In this study we investigated whether stimulation of cells of the innate immune system results in the induction of intestinal glucocorticoids synthesis and what role TNF-alpha plays in this process. Stimulation of the innate immune system with lipopolysaccharide (LPS) led to an up-regulation of colonic steroidogenic enzymes and the induction of intestinal glucocorticoid synthesis. The observed induction was dependent on macrophage effector functions, as depletion of macrophages using clodronate-containing liposomes, but not absence of T and B cells, inhibited intestinal glucocorticoid synthesis. LPS-induced glucocorticoid synthesis was critically dependent on TNF-alpha as it was significantly decreased in TNF-alpha-deficient animals. Both TNF receptor-1 and -2 were found to be equally involved in LPS- and T-cell-induced intestinal GC synthesis. These results describe a novel and critical role of TNF-alpha in immune cell-induced intestinal glucocorticoid synthesis.

Role of complement and perspectives for intervention in ischemia-reperfusion damage

Reperfusion of an organ following prolonged ischemia instigates the pro-inflammatory and pro-coagulant response of ischemia / reperfusion (IR) injury. IR injury is a wide-spread pathology, observed in many clinically relevant situations, including myocardial infarction, stroke, organ transplantation, sepsis and shock, and cardiovascular surgery on cardiopulmonary bypass. Activation of the classical, alternative, and lectin complement pathways and the generation of the anaphylatoxins C3a and C5a lead to recruitment of polymorphonuclear leukocytes, generation of radical oxygen species, up-regulation of adhesion molecules on the endothelium and platelets, and induction of cytokine release. Generalized or pathway-specific complement inhibition using protein-based drugs or low-molecular-weight inhibitors has been shown to significantly reduce tissue injury and improve outcome in numerous in-vitro, ex-vivo, and in-vivo models. Despite the obvious benefits in experimental research, only few complement inhibitors, including C1-esterase inhibitor, anti-C5 antibody, and soluble complement receptor 1, have made it into clinical trials of IR injury. The results are mixed, and the next objectives should be to combine knowledge and experience obtained in the past from animal models and channel future work to translate this into clinical trials in surgical and interventional reperfusion therapy as well as organ transplantation.

Critical roles for Rac GTPases in T-cell migration to and within lymph nodes

Naive T cells continuously recirculate between secondary lymphoid tissue via the blood and lymphatic systems, a process that maximizes the chances of an encounter between a T cell and its cognate antigen. This recirculation depends on signals from chemokine receptors, integrins, and the sphingosine-1-phosphate receptor. The authors of previous studies in other cell types have shown that Rac GTPases transduce signals leading to cell migration and adhesion; however, their roles in T cells are unknown. By using both 3-dimensional intravital and in vitro approaches, we show that Rac1- and Rac2-deficient T cells have multiple defects in this recirculation process. Rac-deficient T cells home very inefficiently to lymph nodes and the white pulp of the spleen, show reduced interstitial migration within lymph node parenchyma, and are defective in egress from lymph nodes. These mutant T cells show defective chemokine-induced chemotaxis, chemokinesis, and adhesion to integrin ligands. They have reduced lateral motility on endothelial cells and transmigrate in-efficiently. These multiple defects stem from critical roles for Rac1 and Rac2 in transducing chemokine and sphingosine-1-phosphate receptor 1 signals leading to motility and adhesion.

TNFR1 is essential for CD40, but not for lipopolysaccharide-induced sickness behavior and clock gene dysregulation

Autoimmune and infectious diseases are associated with behavioral changes referred to as sickness behavior syndrome (SBS). In autoimmunity, the generation of anti-self T lymphocytes and autoantibodies critically involves binding of CD40 ligand on T-cells to its receptor CD40 on B-cells, dendritic cells and macrophages. Activation of CD40 leads to production of proinflammatory cytokines and, as shown here, induces SBS. Here we report that these behavioral changes depend on the expression of tumor necrosis factor alpha receptor 1 (TNFR1), but not on interleukin-1 receptor 1 or interleukin-6. Moreover, the intensity of SBS correlates with suppression of E-box controlled clock genes, including Dbp, and upregulation of Bmal1. However, the absence of TNFR1 does not interfere with the development of SBS and dysregulation of clock genes in mice treated with lipopolysaccharide. Thus, our results suggest that TNFR1 mediates SBS and dysregulation of clock genes in autoimmune diseases.

A novel TNFR1-triggered apoptosis pathway mediated by class IA PI3Ks in neutrophils

The most common form of neutrophil death is apoptosis. In the present study, we report surprising differences in the molecular mechanisms used for caspase activation between FAS/CD95-stimulated and TNF receptor 1 (TNFR1)-stimulated neutrophils. Whereas FAS-induced apoptosis was followed by caspase-8 activation and required Bid to initiate the mitochondrial amplification loop, TNF-?-induced apoptosis involved class IA PI3Ks, which were activated by MAPK p38. TNF-?-induced PI3K activation resulted in the generation of reactive oxygen species, which activated caspase-3, a mechanism that did not operate in neutrophils without active NADPH oxidase. We conclude that in neutrophils, proapoptotic pathways after TNFR1 stimulation are initiated by p38 and PI3K, but not by caspase-8, a finding that should be considered in anti-inflammatory drug-development strategies.

Autologous stem cell transplantation: leukapheresis product has anti-angiogenic effects in vivo correlating with neutrophil-derived VEGFR1

High-dose chemotherapy (HDC) followed by autologous stem cell transplantation (ASCT) is used for the treatment of hemato-oncologic malignancies. In this study, we measured the effect of HDC/ASCT on plasma concentrations of antiangiogenic soluble vascular endothelial growth factor receptor 1 (sVEGFR1) and of leukapheresis products (LP) and patient serum on chick chorioallantoic (CAM) angiogenesis.

Plasma leptin and mRNA expression of lipogenesis and lipolysis-related factors in bovine adipose tissue around parturition

The objective was to study changes in plasma leptin concentration parallel to changes in the gene expression of lipogenic- and lipolytic-related genes in adipose tissue of dairy cows around parturition. Subcutaneous fat biopsies were taken from 27 dairy cows in week 8 antepartum (a.p.), on day 1 postpartum (p.p.) and in week 5 p.p. Blood samples were assayed for concentrations of leptin and non-esterified fatty acids (NEFA). Subcutaneous adipose tissue was analysed for mRNA abundance by real-time qRT-PCR encoding for leptin, adiponectin receptor 1 (AdipoR1), adiponectin receptor 2 (AdipoR2), hormones-sensitive lipase (HSL), perilipin (PLIN), lipoprotein lipase (LPL), acyl-CoA synthase long-chain family member 1 (ACSL1), acetyl-CoA carboxylase (ACC), fatty acid synthase (FASN) and glycerol-3-phosphate dehydrogenase 2 (GPD2). Body weight and body condition score of the cows were lower after parturition than before parturition. The calculated energy balance was negative in week 1 and 5 p.p., with higher negative energy balance in week 1 p.p. compared with that in week 5 p.p. On day 1 p.p., highest concentrations of NEFA (353.3 mumol/l) were detected compared with the other biopsy time-points (210.6 and 107.7 mumol/l, in week 8 a.p., and week 5 p.p. respectively). Reduced plasma concentrations of leptin during p.p. when compared with a.p. would favour increasing metabolic efficiency and energy conservation for mammary function and reconstitution of body reserves. Lower mRNA abundance of ACC and FASN expression on day 1 p.p. compared with other biopsy time-points suggests an attenuation of fatty acid synthesis in subcutaneous adipose tissue shortly after parturition. Gene expression of AdipoR1, AdipoR2, HSL, PLIN, LPL, ACSL1 and GPD2 was unchanged over time.

Glial cell line-derived neurotrophic factor (GDNF) induces neuritogenesis in the cochlear spiral ganglion via neural cell adhesion molecule (NCAM)

Glial cell line-derived neurotrophic factor (GDNF) increases survival and neurite extension of spiral ganglion neurons (SGNs), the primary neurons of the auditory system, via yet unknown signaling mechanisms. In other cell types, signaling is achieved by the GPI-linked GDNF family receptor α1 (GFRα1) via recruitment of transmembrane receptors: Ret (re-arranged during transformation) and/or NCAM (neural cell adhesion molecule). Here we show that GDNF enhances neuritogenesis in organotypic cultures of spiral ganglia from 5-day-old rats and mice. Addition of GFRα1-Fc increases this effect. GDNF/GFRα1-Fc stimulation activates intracellular PI3K/Akt and MEK/Erk signaling cascades as detected by Western blot analysis of cultures prepared from rats at postnatal days 5 (P5, before the onset of hearing) and 20 (P20, after the onset of hearing). Both cascades mediate GDNF stimulation of neuritogenesis, since application of the Akt inhibitor Wortmannin or the Erk inhibitor U0126 abolished GDNF/GFRα1-Fc stimulated neuritogenesis in P5 rats. Since cultures of P5 NCAM-deficient mice failed to respond by neuritogenesis to GDNF/GFRα1-Fc, we conclude that NCAM serves as a receptor for GDNF signaling responsible for neuritogenesis in early postnatal spiral ganglion.

177Lu-AMBA: Synthesis and characterization of a selective 177Lu-labeled GRP-R agonist for systemic radiotherapy of prostate cancer

Gastrin-releasing peptide receptors (GRP-R) are upregulated in many cancers, including prostate, breast, and lung. We describe a new radiolabeled bombesin (BBN) analog for imaging and systemic radiotherapy that has improved pharmacokinetics (PK) and better retention of radioactivity in the tumor. METHODS: DO3A-CH2CO-G-4-aminobenzoyl-Q-W-A-V-G-H-L-M-NH2 (AMBA) was synthesized and radiolabeled. The human prostate cancer cell line PC-3 was used to determine the binding (Kd), retention, and efflux of 177Lu-AMBA. Receptor specificity was determined by in vitro autoradiography in human tissues. PK and radiotherapy studies were performed in PC-3 tumor-bearing male nude mice. RESULTS: 177Lu-AMBA has a high affinity for the GRP-R (Kd, 1.02 nmol/L), with a maximum binding capacity (Bmax) of 414 fmol/10(6) cells (2.5 x 10(5) GRP-R/cell). Internalization was similar for 177Lu-AMBA (76.8%), 177Lu-BBN8 (72.9%), and 125I-[Tyr4]-BBN (74.9%). Efflux was markedly lower for 177Lu-AMBA (2.9%) compared with 177Lu-BBN8 (15.9%) and 125I-[Tyr4]-BBN (46.1%). By receptor autoradiography, Lu-AMBA binds specifically to GRP-R (0.8 nmol/L) and to the neuromedin B receptor (NMB-R) (0.9 nmol/L), with no affinity for the bb3 receptor (>1,000 nmol/L). 177Lu-AMBA was renally excreted (55 %ID 1 h [percentage injected dose at 1 h]); tumor uptake at 1 and 24 h was 6.35 %ID/g and 3.39 %ID/g, respectively. One or 2 doses of 177Lu-AMBA (27.75 MBq/dose) significantly prolonged the life span of PC-3 tumor-bearing mice (P < 0.001 and P < 0.0001, respectively) and decreased PC-3 tumor growth rate over controls. When compared using World Health Organization criteria, mice receiving 2 doses versus 1 dose of 177Lu-AMBA demonstrated a shift away from stable/progressive disease toward complete/partial response; by RECIST (Response Evaluation Criteria in Solid Tumors), median survival increased by 36% and time to progression/progression-free survival increased by 65%. CONCLUSION: 177Lu-AMBA binds with nanomolar affinity to GRP-R and NMB-R, has low retention of radioactivity in kidney, demonstrates a very favorable risk-benefit profile, and is in phase I clinical trials.

The GPIb thrombin-binding site is essential for thrombin-induced platelet procoagulant activity

The role of the platelet glycoprotein (GP) Ib-V-IX receptor in thrombin activation of platelets has remained controversial although good evidence suggests that blocking this receptor affects platelet responses to this agonist. The mechanism of expression of procoagulant activity in response to platelet agonists is also still obscure. Here, the binding site for thrombin on GPIb is shown to have a key role in the exposure of negatively charged phospholipids on the platelet surface and thrombin generation, in response to thrombin, which also requires protease-activated receptor-1, GPIIb-IIIa, and platelet-platelet contact. Von Willebrand factor binding to GPIb is not essential to initiate development of platelet procoagulant activity. Inhibition of fibrinogen binding to GPIIb-IIIa also failed to block platelet procoagulant activity. Both heparin and low molecular weight heparin block thrombin-induced platelet procoagulant activity, which may account for part of their clinical efficacy. This study demonstrates a new, critical role for platelet GPIb in hemostasis, showing that platelet activation and coagulation are tightly interwoven, which may have implications for alternative therapies for thrombotic diseases.

Attenuation of myocardial reperfusion injury in pigs by Mirococept, a membrane-targeted complement inhibitor derived from human CR1

OBJECTIVES: Membrane-targeted application of complement inhibitors may ameliorate ischemia/reperfusion (I/R) injury by directly targeting damaged cells. We investigated whether Mirococept, a membrane-targeted, myristoylated peptidyl construct derived from complement receptor 1 (CR1) could attenuate I/R injury following acute myocardial infarction in pigs. METHODS: In a closed-chest pig model of acute myocardial infarction, Mirococept, the non-tailed derivative APT154, or vehicle was administered intracoronarily into the area at risk 5 min pre-reperfusion. Infarct size, cardiac function and inflammatory status were evaluated. RESULTS: Mirococept targeted damaged vasculature and myocardium, significantly decreasing infarct size compared to vehicle, whereas APT154 had no effect. Cardioprotection correlated with reduced serum troponin I and was paralleled by attenuated local myocardial complement deposition and tissue factor expression. Myocardial apoptosis (TUNEL-positivity) was also reduced with the use of Mirococept. Local modulation of the pro-inflammatory and pro-coagulant phenotype translated to improved left ventricular end-diastolic pressure, ejection fraction and regional wall motion post-reperfusion. CONCLUSIONS: Local modification of a pro-inflammatory and pro-coagulant environment after regional I/R injury by site-specific application of a membrane-targeted complement regulatory protein may offer novel possibilities and insights into potential treatment strategies of reperfusion-induced injury.

Increase in substance P precursor mRNA in noninflamed small-bowel sections in patients with Crohn's disease

BACKGROUND: Neuropeptides, such as substance P (SP), are mediators of neurogenic inflammation and play an important role in inflammatory disorders. To further investigate the role of the SP pathway in inflammatory bowel disease (IBD), we analyzed the following in normal intestinal tissue specimens and in tissue specimens from patients with Crohn's disease (CD) and ulcerative colitis (UC): neurokinin receptor-1 (NK-1R); its isoforms (NK-1R-L and NK-1R-S); its ligand SP, encoded by preprotachykinin-A (PPT-A); and the SP-degradation enzyme, neutral endopeptidase (NEP). METHODS: Real-time quantitative reverse transcription-polymerase chain reaction was used to simultaneously determine the expression of NK-1R-L, NK-1R-S, and PPT-A. Protein levels of NK-1R and NEP were determined by immunoblot analysis. RESULTS: In noninflamed small-bowel tissue samples of CD patients, PPT-A mRNA expression was significantly increased, whereas there was no difference between inflamed or noninflamed UC and normal intestinal tissue samples. Examining subgroups of diverse intestinal segments from CD and UC samples with various levels of inflammation revealed no differences in NK-1R-L and NK-1R-S mRNA expression, whereas there was a tendency toward overall lower NK-1R-S mRNA copy numbers. Immunoblot analysis showed upregulation of NK-1R protein levels in cases of IBD, with more pronounced enhancement in cases of CD than in UC. For NEP, there were no differences in protein levels in normal, CD, and UC intestinal tissues. COMMENTS: These observations suggest a contribution of SP and its receptor, NK-1R, in the local inflammatory reaction in IBD and particularly in ileal CD. Moreover, significant upregulation of PPT-A mRNA in the noninflamed ileum of these patients suggests an influence of inflamed intestines on their healthy counterparts.

CD39 is incorporated into plasma microparticles where it maintains functional properties and impacts endothelial activation

Plasma microparticles (MPs, <1.5 mum) originate from platelet and cell membrane lipid rafts and possibly regulate inflammatory responses and thrombogenesis. These actions are mediated through their phospholipid-rich surfaces and associated cell-derived surface molecules. The ectonucleotidase CD39/ecto-nucleoside triphosphate diphosphohydrolase1 (E-NTPDase1) modulates purinergic signalling through pericellular ATP and ADP phosphohydrolysis and is localized within lipid rafts in the membranes of endothelial- and immune cells. This study aimed to determine whether CD39 associates with circulating MPs and might further impact phenotype and function. Plasma MPs were found to express CD39 and exhibited classic E-NTPDase ecto-enzymatic activity. Entpd1 (Cd39) deletion in mice produced a pro-inflammatory phenotype associated with quantitative and qualitative differences in the MP populations, as determined by two dimensional-gel electrophoresis, western blot and flow cytometry. Entpd1-null MPs were also more abundant, had significantly higher proportions of platelet- and endothelial-derived elements and decreased levels of interleukin-10, tumour necrosis factor receptor 1 and matrix metalloproteinase 2. Consequently, Cd39-null MP augment endothelial activation, as determined by inflammatory cytokine release and upregulation of adhesion molecules in vitro. In conclusion, CD39 associates with circulating MP and may directly or indirectly confer functional properties. Our data also suggest a modulatory role for CD39 within MP in the exchange of regulatory signals between leucocytes and vascular cells.

Haematologic data, iron parameters and molecular findings in two new cases of iron-refractory iron deficiency anaemia

Matriptase-2 (Tmprss6), a type II transmembrane serine protease, has an essential role in iron homoeostasis as a hepcidin regulator. Recently, patients with TMPRSS6 mutations and suffering from iron-refractory iron deficiency anaemia (IRIDA) have been reported. We describe two new cases of IRIDA, one patient of Swiss origin and the second of Italian origin. The first case results from a large deletion of 1054 nucleotides corresponding to an in frame deletion of 30 amino acid residues in the low-density lipoprotein receptor-1/-2 (LDLR-1/-2) domains and from a missense mutation in CUB1 (S304L). In the second case, a homozygous G-->C mutation in the last nucleotide of exon 15 and which modified the consensus sequence of the 5' splice donor site of intron 15 (AGgt-->ACgt) was identified. Both patients had a high hepcidin level and low serum iron and transferrin saturation compared to age-matched controls. Continuous perfusion of i.v. iron 4 h/d x 5 d in the first case resulted in a significant rise in haemoglobin. These new cases of IRIDA illustrate the importance of LDLR-1/-2 and CUB1 domains in matriptase-2 function as well as the role of matriptase-2 in hepcidin regulation. Furthermore a deletional form of TMPRSS6 (in LDLR-1/-2 domains) resulting in IRIDA is described for the first time. These cases reinforce the belief that patients suffering from IRIDA have no specific geographical or ethnic distribution and are sporadic secondary to different mutations of the matriptase-2 gene.

Relationship between inflammation and cognitive function in obstructive sleep apnea

OBJECTIVES: Obstructive sleep apnea (OSA) can have adverse effects on cognitive functioning, mood, and cardiovascular functioning. OSA brings with it disturbances in sleep architecture, oxygenation, sympathetic nervous system function, and inflammatory processes. It is not clear which of these mechanisms is linked to the decrease in cognitive functioning. This study examined the effect of inflammatory parameters on cognitive dysfunction. MATERIALS AND METHODS: Thirty-nine patients with untreated sleep apnea were evaluated by polysomnography and completed a battery of neuropsychological tests. After the first night of evaluation in the sleep laboratory, blood samples were taken for analysis of interleukin 6, tumor necrosis factor-alpha (TNF-alpha), and soluble TNF receptor 1 (sTNF-R1). RESULTS: sTNF-R1 significantly correlated with cognitive dysfunction. In hierarchical linear regression analysis, measures of obstructive sleep apnea severity explained 5.5% of the variance in cognitive dysfunction (n.s.). After including sTNF-R1, percentage of variance explained by the full model increased more than threefold to 19.6% (F = 2.84, df = 3, 36, p = 0.05). Only sTNF-R1 had a significant individual relationship with cognitive dysfunction (beta = 0.376 t = 2.48, p = 0.02). CONCLUSIONS: sTNF-R1 as a marker of chronic inflammation may be associated with diminished neuropsychological functioning in patients with OSA.