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Conjugated linoleic acid (CLA) exerts a protective effect on experimental inflammatory bowel disease and shows promise as a chemopreventive agent against colorectal cancer (CRC) in mice, although the mechanisms by which it exerts its beneficial effects against malignancies in the gut are not completely understood. Mice lacking PPAR[gamma], in immune and epithelial cells and PPAR[gamma]/-expressing littermates were fed either control or CLA-supplemented (1 g CLA/100 g) diets to determine the role of PPAR[gamma], in inflammation-induced CRC. To induce tumor formation and colitis, mice were treated with azoxymethane and then challenged with 2% dextran sodium sulfate, respectively. Dietary CLA ameliorated disease activity, decreased colitis, and prevented adenocarcinoma formation in the PPAR[gamma],-expressing floxed mice but not in the tissue-specific PPAR[gamma]-null mice. Dietary CLA supplementation significantly decreased the percentages of macrophages in the mesenteric lymph nodes (MLN) regardless of the genotype and increased regulatory T cell numbers in MLN of PPAR[gamma]expressing, but not in the tissue-specific, PPAR-),-null mice. Colonic tumor necrosis factor-[alpha] mRNA expression was significantly suppressed in CLA-fed, PPAR[gamma]-expressing mice. This study suggests CLA ameliorates colitis and prevents tumor formation in part through a PPAR[gamma]-dependent mechanism. doi: 10.3945/jn.109.115642.

Mammalian Toll-like receptors (TLRs) 3, 7, 8 and 9 initiate immune responses to infection by recognizing microbial nucleic acids (1,2); however, these responses come at the cost of potential autoimmunity [...]

TLRs may contribute to the progression of rheumatoid arthritis through recognition of microbial or hostderived ligands found in arthritic joints. Here, we show that TLR2 and TLR4, but not TLR9, are involved in the pathogenesis of autoimmune arthritis and play distinct roles in the regulation of T cells and cytokines. We investigated the involvement of TLR2, TLR4, and TLR9 in the progression of arthritis using IL-1 receptor antagonist-knockout (IL1rn-/-) mice, which spontaneously develop an autoimmune T cell-mediated arthritis. Spontaneous onset of arthritis was dependent on TLR activation by microbial flora, as germ-free mice did not develop arthritis. Clinical and histopathological evaluation of IL1rn-/-Tlr2-/- mice revealed more severe arthritis, characterized by reduced suppressive function of Tregs and substantially increased IFN-[gamma] production by T cells. IL1rn-/-Tlr4-/- mice were, in contrast, protected against severe arthritis and had markedly lower numbers of Th17 cells and a reduced capacity to produce IL-17. A lack of Tlr9 did not affect the progression of arthritis. While any therapeutic intervention targeting TLR2 still seems complicated, the strict position of TLR4 upstream of a number of pathogenic cytokines including IL-17 provides an interesting potential therapeutic target for rheumatoid arthritis., Introduction RA is an autoimmune disease manifested by chronic inflammation and cartilage and bone destruction in multiple joints. Etiopathology of RA has been subjected to intensive research, resulting in the [...]

The Frizzled (FZD) family of receptors is critically involved in embryogenesis, and there is substantial evidence that members of this family also regulate tissue homeostasis in many different organs in the adult. FZD receptors have seven transmembrane-spanning domains and are activated by the WNT family of lipo-glycoproteins. Many aspects of FZD signal transduction and pharmacology are still unclear. In this review, we summarize recent advances and some of the key questions about the molecular pharmacology of FZDs, FZD-associated proteins and signal transduction. We also discuss what little is known about the pharmacological binding profiles and the degree of selectivity of WNTs and other extracellular ligands for FZDs. Finally, we focus on signaling events that occur as a direct consequence of FZD activation, signaling via the central phosphoprotein Dishevelled (DVL) and FZD coupling to heterotrimeric G proteins. Here, we outline the current state of knowledge on FZDs and FZD signal transduction and pinpoint aspects of debate and future directions.

ABSTRACT Background Toll-like receptors (TLRs) are essential in host defense against pathogens by virtue of their capacity to detect microbes and initiate the immune response. TLR2 is seen as the [...]

Endothelin-1 (ET-1) is increased in rats on a high-salt (HS) diet and participates in salt-dependent hypertension. Afferent arterioles (AA) are important for long-term blood pressure control, and therefore we hypothesized that a HS diet would alter their responsiveness to ET-1. Sprague-Dawley rats were fed either a normal-salt (NS; 0.66% NaCl) or HS (8%) diet for 1 wk. Diameters of AA were determined in response to increasing concentrations of big ET-1, ET-1, sarafotoxin 6c (S6c), or norepinephrine (NE), using the blood-perfused juxtamedullary nephron technique. ET-1 responses were also determined during blockade of endothelin type A (E[T.sub.A]) or type B (E[T.sub.B]) receptors with 10 nM ABT-627 or 30 nM A-192621, respectively. Expression of E[T.sub.A] and E[T.sub.B] receptors was determined in renal microvessels. Responses of AA to big ET-1, ET-1, and S6c were significantly attenuated during a HS diet (e.g., response to [10.sup.-10] M ET-1 in NS vs. HS rats: -52.5 [+ or -] 10.2 vs. +5.6 [+ or -] 11.3% of control diameter; P < 0.05), with no change in the responses to NE. E[T.sub.B], but not E[T.sub.A] receptor blockade abolished the different response to ET-1 between the NS and HS groups. E[T.sub.B] receptor expression in renal microvessels was increased in response to HS (17.7 [+ or -] 2.4 vs. 6.6 [+ or -] 3.0% of [beta]-actin, P = 0.02), whereas E[T.sub.A] receptor expression was unchanged. These results suggest that the reduced vasoconstrictor response of AA to endothelin peptides during a HS diet is mediated by increased vasodilatory function of endothelial E[T.sub.B] receptors. By preserving renal blood flow, this may be an important mechanism to restore sodium balance during a HS diet. endothelin-1; sodium; renal circulation; hypertension

We recently demonstrated that treatment with the 5-H[T.sub.1A/7] receptor agonist [(R)-(+)-8-hydroxy-2-di-n-propylamino]tetralin (8-OH-DPAT) increases bladder capacity in chloralose-anesthetized female cats with chronic spinal cord injury. In the current study, we investigated the effects of 8-OH-DPAT on bladder capacity and external urethral sphincter (EUS) activity in urethane-anesthetized female rats (initial body mass 175-200 g) with chronic spinal cord injury (transsection at T10). Cystometric study took place 8-12 wk posttranssection. Intravesical pressure was monitored in urethane-anesthetized rats with a transvesical catheter, and EUS activity was assessed electromyographically. Spinal cord injury disrupts phasic activity of the EUS, resulting in decreased voiding efficiency and increased residual volume. 8-OH-DPAT induced a dose-dependent decrease in bladder capacity (the opposite of its effect in chronic spinal cord-injured cats) with an increase in micturition volume and decrease in residual volume resulting from improvement in voiding efficiency. The unexpected improvement in voiding efficiency can be explained by the 8-OH-DPAT-induced emergence of phasic EUS relaxation. Phasic EUS relaxation was also altered by 8-OH-DPAT in spinally intact rats, whereas the 5-H[T.sub.1A] receptor antagonist N-tert-butyl-3-[4-(2-methoxyphenyl)-piperazin-1-yl]-2-phenylpropanamide (WAY-100635), on its own, was without effect. It remains to be determined when phasic relaxation is restored after spinal cord injury, and indeed whether it is ever truly lost or is only temporarily separated from excitatory input. bladder; micturition; neurogenic voiding; detrusor; urethra

Upper urinary tract obstruction results in tubulointerstitial fibrosis and a progressive decline in renal function. Although several inflammatory mediators have been implicated in the pathophysiology of renal obstruction, the contribution of TNF-[alpha] to obstruction-induced fibrosis and renal dysfunction has not been thoroughly evaluated. To study this, male Sprague-Dawley rats were subjected to left unilateral ureteral obstruction vs. sham operation. Rats received either vehicle or a pegylated form of soluble TNF receptor type 1 (PEG-sTNFR1) every 84 h. The kidneys were harvested 1, 3, or 7 days postoperatively, and tissue samples were analyzed for TNF-[alpha] expression (ELISA), macrophage infiltration (ED-1 staining), transforming growth factor-[[beta].sub.1] expression (ELISA, RT-PCR), collagen I and IV activity (Western Blot, immunohistochemistry), [alpha]-smooth muscle actin accumulation (immunohistochemistry, Western blot analysis), and angiotensinogen expression (Western blot). In a separate arm, the glomerular filtration rate (inulin clearance) of rats subjected to unilateral ureteral obstruction in the presence of either vehicle or PEG-sTNFR1 was determined. Renal obstruction induced increased tissue TNF-a and transforming growth factor-[[beta].sub.1] levels, collagen I and IV activity, interstitial volume, [alpha]-smooth muscle actin accumulation, angiotensinogen expression, and renal dysfunction, whereas treatment with PEG-sTNFRI significantly reduced each of these markers of renal fibrosis. These results demonstrate that TNF-[alpha] mediates obstruction-induced renal fibrosis and identify TNF-a neutralization as a potential therapeutic option for the amelioration of obstruction-induced renal injury. kidney; glomerular filtration rate; cytokine; smooth muscle actin; transforming growth factor

Insulin and insulin-like growth factor I (IGF-I) are known to affect cardiovascular disease. We have investigated ligand binding and the dose-response relationship for insulin and IGF-I on vascular smooth muscle cells (VSMCs) at the receptor level. VSMCs from rat thoracic aorta were serum starved, stimulated with IGF-I or insulin, lysed, immunoprecipitated, and analyzed by Western blot. D-[U-[sup.14]C]Glucose accumulation and [6-[sup.3]H]thymidine incorporation into DNA were also measured. Specific binding of both insulin and IGF-I was demonstrated, being higher for IGF-I. Both IGF-I receptor (IGF-IR) and insulin receptor (IR) [beta]-subunits were detected and coprecipitated after immunoprecipitation (IP) against either of the two. No coprecipitation was found after reduction of disulphide bonds with dithiotreitol before IP. After stimulation with [10.sup.-10]-[10.sup.-9] M IGF-I, IP of the IGF-IR, or IR [beta]-subunit and immunoblot with anti-phosphotyrosine antibody, we found two distinct bands indicating phosphorylation of both the IGF-IR and the IR [beta]-subunit. Stimulation with [10.sup.-10]-[10.sup.-9] M insulin and IP against the IGF-IR did not show phosphorylation of either [beta]-subunit, whereas after IP of the IR we found phosphorylation of the IR [beta]-subunit. [[sup.14]C]Glucose accumulation and [[sup.3]H]thymidine incorporation were elevated in cells stimulated with IGF-I at [10.sup.-10]- [10.sup.-7] M, reaching maximum by 10-9 M. Insulin stimulation showed measurable effects only at supraphysiological concentrations, [10.sup.-8]-[10.sup.-7] M. In conclusion, coprecipitation of both the IGF-IR and the IR [beta]-subunit indicates the presence of hybrid insulin/IGF-I receptors in VSMC. At a physiological concentration, insulin activates the IR but does not affect either glucose metabolism or DNA synthesis, whereas IGF-I both activates the receptor and elicits biological effect. insulin-like growth factor I; ligand binding; receptor phosphorylation; immunopreciptation; dexoyribonucleic acid synthesis; glucose metabolism

After menopause, increased tumor necrosis factor-[alpha] (TNF-[alpha]) stimulates bone resorption while inhibiting differentiation of new bone-forming osteoblasts (OB). TNF receptors, p55 and p75, signal similar intracellular pathways, but only p55 activates apoptosis. To evaluate the relationship between the TNF receptor mediating inhibition of OB differentiation and the role of apoptosis, marrow stromal cells (MSC) were cultured from mice deficient in either or both receptors. Cells grown in ascorbate and [beta]-glycerophosphate produce alkaline phosphatase and osteocalcin and mineralize matrix. Treatment of wild-type or [p55.sup.+/+]/[p75.sup.-/-] MSC with murine TNF (binds p55 and p75) or human TNF (binds only p55) inhibited OB differentiation. TNF did not inhibit OB differentiation in [p55.sup.-/-] MSC. Expression of p75 modestly attenuated sensitivity to TNF. To determine the role of apoptosis, changes in total DNA, cell viability, caspase 3, and percentage of annexin V-positive cells were measured in MSC and preosteoblastic MC3T3 cells. TNF treatment that reduced differentiation by 50% did not decrease cell viability or increase apoptosis, as determined by alamar blue reduction, trypan blue exclusion, and percentage of annexin V-positive cells. TNF increased caspase 3 activity 1.5-fold in MC3T3 and insignificantly in MSC cells compared with >4-fold after 4 h actinomycin D. Treatment of MSC or MC3T3 cells with three caspase inhibitors failed to reverse the inhibitory effect of TNF on OB differentiation despite inhibition of caspase activity. These results suggest that the p55 receptor is essential, and p75 dispensable, for TNF inhibition of OB differentiation through a mechanism that does not require apoptosis. osteoblast; p75; tumor necrosis factor receptor 1; tumor necrosis factor receptor 2; bone; osteoporosis; tumor necrosis factor; apoptosis

People with advanced melanoma are living longer thanks to treatments that target cancerous cells or encourage the immune system to wipe out the tumour., Author(s): Hannah Hoag [sup.1] Author Affiliations: (1) Hannah Hoag is a freelance science writer based in Toronto, Canada., When Antoni Ribas began treating metastatic melanoma 15 years ago, he faced [...]