Hepatic-portal vein infusions of glucagon-like peptide-1 reduce meal size and increase c-Fos expression in the nucleus tractus solitarii, area postrema and central nucleus of the amygdala in rats

We recently reported that brief, remotely controlled intrameal hepatic-portal vein infusions of glucagon-like peptide-1 (GLP-1) reduced spontaneous meal size in rats. To investigate the neurobehavioural correlates of this effect, we equipped male Sprague-Dawley rats with hepatic-portal vein catheters and assessed (i) the effect on eating of remotely triggered infusions of GLP-1 (1 nmol/kg, 5 min) or vehicle during the first nocturnal meal after 3 h of food deprivation and (ii) the effect of identical infusions performed at dark onset on c-Fos expression in several brain areas involved in the control of eating. GLP-1 reduced (P < 0.05) the size of the first nocturnal meal and increased its satiety ratio. Also, GLP-1 increased (P < 0.05) the number of c-Fos-expressing cells in the nucleus tractus solitarii, the area postrema and the central nucleus of the amygdala, but not in the arcuate or paraventricular hypothalamic nuclei. These data suggest that the nucleus tractus solitarii, the area postrema and the central nucleus of the amygdala play a role in the eating-inhibitory actions of GLP-1 infused into the hepatic-portal vein; it remains to be established whether activation of these brain nuclei reflect satiation, aversion, or both.

The transcriptional regulator megakaryoblastic leukemia-1 mediates serum response factor-independent activation of tenascin-C transcription by mechanical stress

The extracellular matrix protein tenascin-C (TNC) is up-regulated in processes influenced by mechanical stress, such as inflammation, tissue remodeling, wound healing, and tumorigenesis. Cyclic strain-induced TNC expression depends on RhoA-actin signaling, the pathway that regulates transcriptional activity of serum response factor (SRF) by its coactivator megakaryoblastic leukemia-1 (MKL1). Therefore, we tested whether MKL1 controls TNC transcription. We demonstrate that overexpression of MKL1 strongly induces TNC expression in mouse NIH3T3 fibroblasts and normal HC11 and transformed 4T1 mammary epithelial cells. Part of the induction was dependant on SRF and a newly identified atypical CArG box in the TNC promoter. Another part was independent of SRF but required the SAP domain of MKL1. An MKL1 mutant incapable of binding to SRF still strongly induced TNC, while induction of the SRF target c-fos was abolished. Cyclic strain failed to induce TNC in MKL1-deficient but not in SRF-deficient fibroblasts, and strain-induced TNC expression strongly depended on the SAP domain of MKL1. Promoter-reporter and chromatin immunoprecipitation experiments unraveled a SAP-dependent, SRF-independent interaction of MKL1 with the proximal promoter region of TNC, attributing for the first time a functional role to the SAP domain of MKL1 in regulating gene expression.

Saliva suppresses osteoclastogenesis in murine bone marrow cultures.

Saliva can reach mineralized surfaces in the oral cavity; however, the relationship between saliva and bone resorption is unclear. Herein, we examined whether saliva affects the process of osteoclastogenesis in vitro. We used murine bone marrow cultures to study osteoclast formation. The addition of fresh sterile saliva eliminated the formation of multinucleated cells that stained positive for tartrate-resistant acid phosphatase (TRAP). In line with the histochemical staining, saliva substantially reduced gene expression of cathepsin K, calcitonin receptor, and TRAP. Addition of saliva led to considerably decreased gene expression of receptor activator of nuclear factor kappa-B (RANK) and, to a lesser extent, that of c-fms. The respective master regulators of osteoclastogenesis (c-fos and NFATc1) and the downstream cell fusion genes (DC-STAMP and Atp6v0d2) showed decreased expression after the addition of saliva. Among the costimulatory molecules for osteoclastogenesis, only OSCAR showed decreased expression. In contrast, CD40, CD80, and CD86-all costimulatory molecules of phagocytic cells-were increasingly expressed with saliva. The phagocytic capacity of the cells was confirmed by latex bead ingestion. Based on these in vitro results, it can be concluded that saliva suppresses osteoclastogenesis and leads to the development of a phagocytic cell phenotype.

Conditioned medium from fresh and demineralized bone enhances osteoclastogenesis in murine bone marrow cultures

OBJECTIVES Osteoclasts rapidly form on the surface of bone chips at augmentation sites. The underlying molecular mechanism, however, is unclear. Soluble factors released from bone chips in vitro have a robust impact on mesenchymal cell differentiation. Whether these soluble factors change the differentiation of hematopoietic cells into osteoclasts remains unknown. METHODS Osteoclastogenesis, the formation of tartrate-resistant acid phosphatase-positive multinucleated cells, was studied with murine bone marrow cultures exposed to RANKL and M-CSF, and conditioned medium from fresh (BCM) and demineralized bone matrix (DCM). Histochemical staining, gene and protein expression, as well as viability assays were performed. RESULTS This study shows that BCM had no impact on osteoclastogenesis. However, when BCM was heated to 85°C (BCMh), the number of tartrate-resistant acid phosphatase-positive multinucleated cells that developed in the presence of RANKL and M-CSF approximately doubled. In line with the histochemical observations, there was a trend that BCMh increased expression of osteoclast marker genes, in particular the transcription factor c-fos. The expression of c-fos was significantly reduced by the TGF-β receptor I antagonist SB431542. DCM significantly stimulated osteoclastogenesis, independent of thermal processing. CONCLUSIONS These data demonstrate that activated BCM by heat and DBM are able to stimulate osteoclastogenesis in vitro. These in vitro results support the notion that the resorption of autografts may be supported by as yet less defined paracrine mechanisms.

TNFα inhibits the development of osteoclasts through osteoblast-derived GM-CSF

Inflammatory cytokines such as tumor necrosis factor-alpha (TNFα) are potent stimulators of osteoclast formation and bone resorption and are frequently associated with pathologic bone metabolism. The cytokine exerts specific effects on its target cells and constitutes a part of the cellular microenvironment. Previously, TNFα was demonstrated to inhibit the development of osteoclasts in vitro via an osteoblast-mediated pathway. In the present study, the molecular mechanisms of the inhibition of osteoclastogenesis were investigated in co-cultures of osteoblasts and bone marrow cells (BMC) and in cultures of macrophage-colony stimulating factor (M-CSF) dependent, non-adherent osteoclast progenitor cells (OPC) grown with M-CSF and receptor activator of NF-κB ligand (RANKL). Granulocyte-macrophage colony stimulating factor (GM-CSF), a known inhibitor of osteoclastogenesis was found to be induced in osteoblasts treated with TNFα and the secreted protein accumulated in the supernatant. Dexamethasone (Dex), an anti-inflammatory steroid, caused a decrease in GM-CSF expression, leading to partial recovery of osteoclast formation. Flow cytometry analysis revealed that in cultures of OPC, supplemented with 10% conditioned medium (CM) from osteoblasts treated with TNFα/1,25(OH)(2)D(3), expression of RANK and CD11c was suppressed. The decrease in RANK expression may be explained by the finding, that GM-CSF and the CM from wt osteoblasts were found to suppress the expression of c-Fos, Fra-1, and Nfatc-1. The failure of OPC to develop into CD11c(+) dendritic cells suggests that cell development is not deviated to an alternative differentiation pathway, but rather, that the monocytes are maintained in an undifferentiated, F4/80(+), state. The data further implies possible interactions among inflammatory cytokines. GM-CSF induced by TNFα acts on early hematopoietic precursors, inhibiting osteoclastogenesis while acting as the growth factor for M-CSF independent inflammatory macrophages. These in turn may condition a microenvironment enhancing osteoclast differentiation and bone resorption upon migration of the OPC from circulation to the bone/bone marrow compartment.

Processing of temporal unpredictability in human and animal amygdala

The amygdala has been studied extensively for its critical role in associative fear conditioning in animals and humans. Noxious stimuli, such as those used for fear conditioning, are most effective in eliciting behavioral responses and amygdala activation when experienced in an unpredictable manner. Here, we show, using a translational approach in mice and humans, that unpredictability per se without interaction with motivational information is sufficient to induce sustained neural activity in the amygdala and to elicit anxiety-like behavior. Exposing mice to mere temporal unpredictability within a time series of neutral sound pulses in an otherwise neutral sensory environment increased expression of the immediate-early gene c-fos and prevented rapid habituation of single neuron activity in the basolateral amygdala. At the behavioral level, unpredictable, but not predictable, auditory stimulation induced avoidance and anxiety-like behavior. In humans, functional magnetic resonance imaging revealed that temporal unpredictably causes sustained neural activity in amygdala and anxiety-like behavior as quantified by enhanced attention toward emotional faces. Our findings show that unpredictability per se is an important feature of the sensory environment influencing habituation of neuronal activity in amygdala and emotional behavior and indicate that regulation of amygdala habituation represents an evolutionary-conserved mechanism for adapting behavior in anticipation of temporally unpredictable events.

Toll-like receptor 2 is highly expressed in lesions of acne inversa and colocalizes with C-type lectin receptor

BACKGROUND: Acne inversa (hidradenitis suppurativa) is a chronic inflammatory and cicatricial disorder that affects skin areas rich in apocrine glands and terminal hairs, such as perineum and axillae. The exact pathogenesis of the disease is not well understood and the mechanisms by which bacterial superinfection contributes to the disease progression are not clear. Toll-like receptors (TLRs) expressed by inflammatory cells play a crucial role in the innate immune response to bacteria. OBJECTIVES: We sought to investigate the role of TLR2 in the pathogenesis of acne inversa. METHODS: We investigated the expression of TLR2 using real-time polymerase chain reaction analysis and immunohistochemical stainings of tissue samples from patients with acne inversa. Furthermore, we phenotypically characterized the infiltrating cells and their expression of TLR2. RESULTS: Compared with normal skin, a highly increased in situ expression of TLR2 in acne inversa skin lesions was found at both the mRNA and the protein level. The most abundant cells in the dermal infiltrate of acne inversa were CD68+ macrophages, CD209+ dendritic cells (DCs) and CD3+ T cells. CD19+ B cells and CD56+ natural killer cells were found only in small numbers. Double staining with fluorescence-labelled antibodies showed that TLR2 was expressed by infiltrating macrophages (CD68+) and DCs (CD209+). Flow cytometric analysis of isolated infiltrating cells further confirmed surface expression of TLR2 by macrophages and DCs. CONCLUSIONS: These data indicate that the enhanced expression of TLR2 by infiltrating macrophages and DCs may contribute to the pathogenesis of inflammatory lesions of acne inversa.

Cardiac c-kit+AT2+ cell population is increased in response to ischemic injury and supports cardiomyocyte performance

The expression pattern of angiotensin AT2 receptors with predominance during fetal life and upregulation under pathological conditions during tissue injury/repair process suggests that AT2 receptors may exert an important action in injury/repair adaptive mechanisms. Less is known about AT2 receptors in acute ischemia-induced cardiac injury. We aimed here to elucidate the role of AT2 receptors after acute myocardial infarction. Double immunofluorescence staining showed that cardiac AT2 receptors were mainly detected in clusters of small c-kit+ cells accumulating in peri-infarct zone and c-kit+AT2+ cells increased in response to acute cardiac injury. Further, we isolated cardiac c-kit+AT2+ cell population by modified magnetic activated cell sorting and fluorescence activated cell sorting. These cardiac c-kit+AT2+ cells, represented approximately 0.19% of total cardiac cells in infarcted heart, were characterized by upregulated transcription factors implicated in cardiogenic differentiation (Gata-4, Notch-2, Nkx-2.5) and genes required for self-renewal (Tbx-3, c-Myc, Akt). When adult cardiomyocytes and cardiac c-kit+AT2+ cells isolated from infarcted rat hearts were cocultured, AT2 receptor stimulation in vitro inhibited apoptosis of these cocultured cardiomyocytes. Moreover, in vivo AT2 receptor stimulation led to an increased c-kit+AT2+ cell population in the infarcted myocardium and reduced apoptosis of cardiomyocytes in rats with acute myocardial infarction. These data suggest that cardiac c-kit+AT2+ cell population exists and increases after acute ischemic injury. AT2 receptor activation supports performance of cardiomyocytes, thus contributing to cardioprotection via cardiac c-kit+AT2+ cell population.

[Cryptosporidiose (C. parvum) in a foal with diarrhea]

The protozoon parasite Cryptosporidium parvum is an important cause of diarrhea in farm animals, but it can also infect other animals and humans. In this case report, oocysts of Cryptosporidium spp. were microscopically detected by modified Ziehl-Neelsen staining in the feces of a 9 day old Arabian colt presented with yellowish, foul smelling, diarrhea and fever of 40 degrees C. PCR and sequencing of the isolate revealed C. parvum (bovine genotype). Hemato-chemical analysis of the foals blood revealed a marked hypogammaglobulinaemia (IgG 108mg/dl). The colt responded well to a supportive therapy and administration of plasma (until a gammaglobulin-concentration of 620 mg/dl was reached) and was released in good health from the clinic after 10 days. Follow-up testing for Cryptosporidium oocycsts remained negative. Cryptosporidiosis with life-threatening diarrhea is a rare diagnosis in foals in Switzerland. Immunodeficiency increases the risk for cryptosporidiosis. We hypothesize that the low concentration of gammaglobulins together with the weak INF-gamma response normally observed in young foals may have favored the clinical manifestation with diarrhea. Foals with diarrhea should be screened for cryptosporidia with specific tests.