Blockade of Tumor Necrosis Factor (TNF) Receptor Type 1-Mediated TNF-α Signaling Protected Wistar Rats from Diet-Induced Obesity and Insulin Resistance

Endocrinology ◽  
2008 ◽  
Vol 149 (6) ◽  
pp. 2943-2951 ◽  
Author(s):  
Huifang Liang ◽  
Bingjiao Yin ◽  
Hailong Zhang ◽  
Shu Zhang ◽  
Qingling Zeng ◽  
...  
2007 ◽  
Vol 86 (11) ◽  
pp. 1089-1094 ◽  
Author(s):  
I. Andrade ◽  
T.A. Silva ◽  
G.A.B. Silva ◽  
A.L. Teixeira ◽  
M.M. Teixeira

Orthodontic tooth movement is dependent on osteoclast activity. Tumor necrosis factor (TNF)-α plays an important role, directly or via chemokine release, in osteoclast recruitment and activation. This study aimed to investigate whether the TNF receptor type 1 (p55) influences these events and, consequently, orthodontic tooth movement. An orthodontic appliance was placed in wild-type mice (WT) and p55-deficient mice (p55−/−). Levels of TNF-α and 2 chemokines (MCP-1/CCL2, RANTES/CCL5) were evaluated in periodontal tissues. A significant increase in CCL2 and TNF-α was observed in both groups after 12 hrs of mechanical loading. However, CCL5 levels remained unchanged in p55−/− mice at this time-point. The number of TRAP-positive osteoclasts in p55−/− mice was significantly lower than that in WT mice. Also, there was a significantly smaller rate of tooth movement in p55−/− mice. Analysis of our data suggests that the TNFR-1 plays a significant role in orthodontic tooth movement that might be associated with changes in CCL5 levels.


1999 ◽  
Vol 67 (8) ◽  
pp. 4231-4236 ◽  
Author(s):  
Cheng-Yang Chiang ◽  
George Kyritsis ◽  
Dana T. Graves ◽  
Salomon Amar

ABSTRACT The present study was undertaken to test the hypothesis that tumor necrosis factor (TNF) and/or interleukin-1 (IL-1) activity mediates lipopolysaccharide (LPS)-induced bone resorption in vivo. To test this hypothesis, Escherichia coli LPS or Porphyromonas gingivalis LPS was injected into the subcutaneous tissues overlying mouse calvariae. Histological sections, prepared from the center of the lesion, were stained for tartrate-resistant acid phosphatase, and histomorphometric analysis was performed to quantify the osteoclast number and the area of bone resorption. In time course experiments using normal mice, a peak of bone resorption occurred 5 days after endotoxin stimulation. In dose-response experiments, IL-1 receptor type 1 deletion (IL-1R−/−), TNF double-receptor p55/p75 deletion (TNF p55−/−/p75−/−), combined TNF p55 and IL-1 receptor type 1 deletion (TNF p55−/−/IL-1R−/−), and IL-1β-converting enzyme-deficient (ICE−/−) mice and the respective wild-type mice were injected with 500, 100, or 20 μg of P. gingivalis LPS and sacrificed 5 days after LPS injection. At the highest dose (500 μg), significant decreases in osteoclast number occurred in mutant mice compared to wild-type mice: (i) a 64% reduction for the TNF p55−/−/IL-1R−/− mice, (ii) a 57% reduction for the IL-1R−/− mice, (iii) a 41% reduction for the TNF p55−/−/p75−/− mice, and (iv) a 38% reduction for the ICE−/− mice. At the two lower doses, bone resorption was apparent but no significant differences between mutant and wild-type animals were observed. The present data indicate that at higher doses, LPS-induced bone resorption is substantially mediated by IL-1 and TNF receptor signaling. Furthermore, IL-1 receptor signaling appears to be slightly more important than TNF receptor signaling. At lower LPS doses, other pathways leading to osteoclast activity that are independent of TNF and IL-1 are involved.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4149-4149
Author(s):  
Claudia Duerr ◽  
Angela Schulz ◽  
Sibylle Ohl ◽  
Thorsten Zenz ◽  
Stephan Stilgenbauer ◽  
...  

Abstract B-cell Chronic Lymphocytic Leukemia (CLL) represents the most common leukemia among adults in the western world and remains still incurable. CLL is characterized by the accumulation of malignant B-cells in the peripheral blood and the lymphoid organs due to apoptosis resistance. Removing the cells from their physiological microenvironment spontaneously drives them into apoptosis in vitro unless they are supported by bystander cells (e.g. stromal cells or accessory leukocytes) or soluble factors such as cytokines produced by these cells. In order to identify differences in the biology of healthy B-cells and the leukemic clones we performed comparative microarray analyses of both cell types before and after cultivation in high cell density that allows cell-cell interactions of CLL cells with accessory leukocytes. These studies revealed the establishment of an inflammatory microenvironment in CLL characterized by the transcriptional upregulation of several cytokines. Antibody array analyses of culture supernatants and blood serum samples confirmed the upregulation of these proteins and their relevance for CLL. The 11 most deregulated cytokines were quantified in the serum of 250 CLL patients of the German CLL8 study cohort and 50 age- and sex-matched controls in order to identify novel predictive or prognostic markers. Bioinformatical analyses of the data are currently ongoing. Among other proteins, we found Tumor Necrosis Factor Receptor Type 1 (TNFR-1) to be significantly upregulated in the malignant B-cells under survival-maintaining cultivation as well as in CLL serum, but not in healthy controls (Figure 1). To exploit the difference in TNFR-1 biology, we treated CLL cells with TNF-α in combination with wogonin which is known to block the survival supporting pathway propagated by TNFR-1 upon TNF-α binding. This combinational treatment strategy effectively triggered Disclosures: No relevant conflicts of interest to declare.


1999 ◽  
Vol 189 (11) ◽  
pp. 1707-1714 ◽  
Author(s):  
Eberhard Hildt ◽  
Stefanie Oess

Tumor necrosis factor α (TNF-α) is a proinflammatory cytokine. Its pleiotropic biological properties are signaled through two distinct cell surface receptors: the TNF receptor type I (TNFR-I) and the TNF receptor type II. Neither of the two receptors possesses tyrosine kinase activity. A large majority of TNF-α–dependent activities can be mediated by TNFR-I. Recently, c-Raf-1 kinase was identified as an intracellular target of a signal transduction cascade initiated by binding of TNF-α to TNFR-I. However, the mechanism engaged in TNF-α–dependent activation of c-Raf-1 kinase is still enigmatic. Here we report that the cytosolic adapter protein Grb2 is a novel binding partner of TNFR-I. Grb2 binds with its COOH-terminal SH3 domain to a PLAP motif within TNFR-I and with its NH2-terminal SH3 domain to SOS (son of sevenless). A PLAP deletion mutant of TNFR-I fails to bind Grb2. The TNFR-I/Grb2 interaction is essential for the TNF-α–dependent activation of c-Raf-1 kinase; activation of c-Raf-1 kinase by TNF-α can be blocked by coexpression of Grb2 mutants harboring inactivating point mutations in the NH2- or COOH-terminal SH3 domain, cell-permeable peptides that disrupt the Grb2/TNFR-I interaction or transdominant negative Ras. Functionality of the TNFR-I/Grb2/SOS/Ras interaction is a prerequisite but not sufficient for TNF-α–dependent activation of c-Raf-1 kinase. Inhibition of the TNFR-I/FAN (factor associated with neutral sphingomyelinase) interaction, which is essential for TNF-α–dependent activation of the neutral sphingomyelinase, either by cell-permeable peptides or by deletion of the FAN binding domain, prevents activation of c-Raf-1 kinase. In conclusion, binding of the Grb2 adapter protein via its COOH-terminal SH3 domain to the nontyrosine kinase receptor TNFR-I results in activation of a signaling cascade known so far to be initiated, in the case of the tyrosine kinase receptors, by binding of the SH2 domain of Grb2 to phosphotyrosine.


2012 ◽  
Vol 302 (12) ◽  
pp. F1650-F1657 ◽  
Author(s):  
Alexander Castillo ◽  
M. Toriqul Islam ◽  
Minolfa C. Prieto ◽  
Dewan S. A. Majid

Acute administration of tumor necrosis factor-α (TNF-α) resulted in decreases in renal blood flow (RBF) and glomerular filtration rate (GFR) but induced diuretic and natriuretic responses in mice. To define the receptor subtypes involved in these renal responses, experiments were conducted to assess the responses to human recombinant TNF-α (0.3 ng·min−1·g body wt−1iv infusion for 75 min) in gene knockout (KO) mice for TNF-α receptor type 1 (TNFαR1 KO, n = 5) or type 2 (TNFαR2 KO, n = 6), and the results were compared with those obtained in corresponding wild-type [WT (C57BL/6), n = 6] mice. Basal levels of RBF (PAH clearance) and GFR (inulin clearance) were similar in TNFαR1 KO, but were lower in TNFαR2 KO, than WT mice. TNF-α infusion in WT mice decreased RBF and GFR but caused a natriuretic response, as reported previously. In TNFαR1 KO mice, TNF-α infusion failed to cause such vasoconstrictor or natriuretic responses; rather, there was an increase in RBF and a decrease in renal vascular resistance. Similar responses were also observed with infusion of murine recombinant TNF-α in TNFαR1 KO mice ( n = 5). However, TNF-α infusion in TNFαR2 KO mice caused changes in renal parameters qualitatively similar to those observed in WT mice. Immunohistochemical analysis in kidney slices from WT mice demonstrated that while both receptor types were generally located in the renal vascular and tubular cells, only TNFαR1 was located in vascular smooth muscle cells. There was an increase in TNFαR1 immunoreactivity in TNFαR2 KO mice, and vice versa, compared with WT mice. Collectively, these functional and immunohistological findings in the present study demonstrate that the activation of TNFαR1, not TNFαR2, is mainly involved in mediating the acute renal vasoconstrictor and natriuretic actions of TNF-α.


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