Ceramide and ceramide 1-phosphate are negative regulators of TNF-α production induced by lipopolysaccharide

LPS is a constituent of cell walls of Gram-negative bacteria that, acting through the CD14/TLR4 receptor complex, causes strong proinflammatory activation of macrophages. In murine peritoneal macrophages and J774 cells, LPS at 1-2 ng/ml induced maximal TNF-α and MIP-2 release, and higher LPS concentrations were less effective, which suggested a negative control of LPS action. While studying the mechanism of this negative regulation, we found that in J774 cells, LPS activated both acid sphingomyelinase and neutral sphingomyelinase and moderately elevated ceramide, ceramide 1-phosphate, and sphingosine levels. Lowering of the acid sphingomyelinase and neutral sphingomyelinase activities using inhibitors or gene silencing upregulated TNF-α and MIP-2 production in J774 cells and macrophages. Accordingly, treatment of those cells with exogenous C8-ceramide diminished TNF-α and MIP-2 production after LPS stimulation. Exposure of J774 cells to bacterial sphingomyelinase or interference with ceramide hydrolysis using inhibitors of ceramidases also lowered the LPS-induced TNF-α production. The latter result indicates that ceramide rather than sphingosine suppresses TNF-α and MIP-2 production. Of these two cytokines, only TNF-α was negatively regulated by ceramide 1-phosphate as was indicated by upregulated TNF-α production after silencing of ceramide kinase gene expression. None of the above treatments diminished NO or RANTES production induced by LPS. Together the data indicate that ceramide negatively regulates production of TNF-α and MIP-2 in response to LPS with the former being sensitive to ceramide 1-phosphate as well. We hypothesize that the ceramide-mediated anti-inflammatory pathway may play a role in preventing endotoxic shock and in limiting inflammation.     

TNF-α -308 genotypes are associated with TNF-α and TGF-β₁ mRNA expression in blood leucocytes of humans

AimTumor necrosis factor α (TNF-α) influences the pathogenesis of lung-fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene are suggested to be associated with susceptibility to lung-diseases. Additionally TNF-α is postulated to play a significant role in regulating. Transforming growth factor (TGF-β₁) expression Therefore we investigated if the TNF-α or TGF-β₁ gene expression level is different within the ?308 TNF-α genotypes.MethodsQuantitative Real-time PCR of TNF-α and TGF-β₁ was performed in 178 Germans. Calculations of expression were made with the 2^?ΔΔCT method. Detection of the ?308 promoter polymorphism of the TNF-α gene was performed by rapid capillary PCR with melting curve analysis.ResultsThe relative TNF-α mRNA expression revealed significant differences between the TNF-α ?308 homozygote wild-type G/G (0.00079 ± 0.00011; n = 113) and the heterozygote genotype G/A (0.0005 ± 0.00008; n = 52; p = 0.030) as well as between homozygote wild-type G/G and the homozygote mutant A/A (0.00029 ± 0.00009; n = 5; p = 0.004). The relative TGF-β mRNA expression showed, similar to TNF-α, the highest mRNA expression was seen within the TNF-α ?308 homozygote wild-types, while the lowest mRNA expression lay within the homozygote mutant-types.ConclusionOur findings suggest that the G-allele of TNF-α ?308 is associated with a significantly higher TNF-α mRNA expression compared to the A-allele and that this also reflects in TGF-β expression. Therefore we support the thesis that TGF-β is regulated by TNF-α.     

Acute-phase cytokines IL-1β and TNF-α in brain development

The nervous and the immune systems share several molecules that control their development and function. We studied the temporal and spatial distribution of the immunoreactivity of two acute-phase cytokines, TNF-alpha and IL-1beta, in the developing sheep neocortex and compared it with the well-described distribution of fetuin, a fetal glycoprotein also known to modulate the production of cytokines by lipopolysaccharide (LPS)-stimulated monocytes and macrophages. TNF-alpha was present first at embryonic day 30 (E30) (term is 150 days in sheep) as a faint band of immunoreactivity between the ventricular zone and the primordial plexiform layer (preplate). IL-1beta was detected at the first appearance of the cortical plate (E35-E40). Both cytokines were present on both sides of the cortical plate, which contained fetuin-positive cells, but was free from cytokine staining. By E60, TNF-alpha immunoreactivity was less prominent than that of IL-1beta and was confined to the marginal zone and outer developing white matter; IL-1beta was present in the marginal zone and in two bands of immunoreactive cells, one at the border of the cortical plate/developing layer VI (cells of neuronal morphology) and the other at the border of layer V and the developing white matter (identified as microglia). By E80, TNF-alpha staining had disappeared and IL-1beta-immunopositive microglia were no longer detectable. By E100-E140 only a few immunoreactive cells were identified in layers V-VI; these did not co-localize with fetuin-positive cells. The differences in distribution between fetuin and the two cytokines suggest that the opsonizing role of fetuin, proposed for monocyte production of cytokines, is probably not present in the developing brain. However, early in neocortical development TNF-alpha and IL-1beta were present in the subplate zone at a time of intense synaptogenesis.     

Suppressing IL-32 in monocytes impairs the induction of the proinflammatory cytokines TNFα and IL-1β

Targeting major proinflammatory cytokines such as IL-1β and TNFα is of great interest in patients with chronic inflammatory diseases, including rheumatoid arthritis, colitis, and psoriasis. The cytokine Interleukin (IL)-32 induces proinflammatory cytokines such as TNFα, IL-1β, IL-6, and chemokines. We previously used an IL-32 ligand-affinity column to purify proteinase 3, which is abundantly expressed in neutrophil and monocytic leukocytes but not in other cell types, and found that IL-32 is mainly produced by monocytic leukocytes. This evidence suggested that silencing endogenous IL-32 by short hairpin RNA (shRNA) in monocytic cells might reveal the precise function of endogenous IL-32. Indeed, lipopolysaccharide (LPS)- or phorbol myristate acetate (PMA)-induced proinflammatory cytokine production was significantly inhibited in shRNA/IL-32 stable clones as compared to control clones. Furthermore, macrophages in PMA-differentiated shRNA/IL-32 stable clones displayed remarkably impaired LPS- and IL-1β-induced proinflammatory cytokine production. These data suggest that IL-32 is not only involved in host defense against pathogens, but also might play a role in chronic inflammatory diseases. IL-32 production leads to major proinflammatory cytokine production during the initial immune response.     

Smad7 and protein phosphatase 1α are critical determinants in the duration of TGF-β/ALK1 signaling in endothelial cells

Background  

In endothelial cells (EC), transforming growth factor-β (TGF-β) can bind to and transduce signals through ALK1 and ALK5. The TGF-β/ALK5 and TGF-β/ALK1 pathways have opposite effects on EC behaviour. Besides differential receptor binding, the duration of TGF-β signaling is an important specificity determinant for signaling responses. TGF-β/ALK1-induced Smad1/5 phosphorylation in ECs occurs transiently.     

Mutual regulation of TGF-β1, TβRII and ErbB receptors expression in human thyroid carcinomas

The role of EGF and TGF-β1 in thyroid cancer is still not clearly defined. TGF-β1 inhibited the cellular growth and migration of follicular (FTC-133) and papillary (B-CPAP) thyroid carcinoma cell lines. Co-treatments of TGF-β1 and EGF inhibited proliferation in both cell lines, but displayed opposite effect on their migratory capability, leading to inhibition in B-CPAP and promotion in FTC-133 cells, by a MAPK-dependent mechanism. TGF-β1, TβRII and EGFR expressions were evaluated in benign and malignant thyroid tumors. Both positivity (51.7% and 60.0% and 80.0% in FA and PTC and FTC) and overexpression (60.0%, 77.7% and 75.0% in FA, PTC and FTC) of EGFR mRNA correlates with the aggressive tumor behavior. The moderate overexpression of TGF-β1 and TβRII mRNA in PTC tissues (61.5% and 62.5%, respectively), counteracted their high overexpression in FTC tissues (100% and 100%, respectively), while EGFR overexpression was similar in both carcinomas. Papillary carcinomas were positive to E-cadherin expression, while the follicular carcinomas lose E-cadherin staining. Our findings of TGF-β1/TβRII and EGFR overexpressions together with a loss of E-cadherin observed in human follicular thyroid carcinomas, and of increased migration ability MAPK-dependent after EGF/TGF-β1 treatments in the follicular thyroid carcinoma cell line, reinforced the hypothesis of a cross-talk between EGF and TGF-β1 systems in follicular thyroid carcinomas phenotype.     

Characterization and Identification of Subpopulations of Mononuclear Preosteoclasts Induced by TNF-α in Combination with TGF-β in Rats

Osteoclasts are unique multinucleated cells formed by fusion of preosteoclasts derived from cells of the monocyte/macrophage lineage, which are induced by RANKL. However, characteristics and subpopulations of osteoclast precursor cells are poorly understood. We show here that a combination of TNF-α, TGF-β, and M-CSF efficiently generates mononuclear preosteoclasts but not multinucleated osteoclasts (MNCs) in rat bone marrow cultures depleted of stromal cells. Using a rat osteoclast-specific mAb, Kat1, we found that TNF-α and TGF-β specifically increased Kat1⁺c-fms⁺ and Kat1⁺c-fms⁻ cells but not Kat1⁻c-fms⁺ cells. Kat1⁻c-fms⁺ cells appeared in early stages of culture, but Kat1⁺c-fms⁺ and Kat1⁺c-fms⁻ cells increased later. Preosteoclasts induced by TNF-α, TGF-β, and M-CSF rapidly differentiated into osteoclasts in the presence of RANKL and hydroxyurea, an inhibitor of DNA synthesis, suggesting that preosteoclasts are terminally differentiated cells. We further analyzed the expression levels of genes encoding surface proteins in bone marrow macrophages (BMM), preosteoclasts, and MNCs. Preosteoclasts expressed itgam (CD11b) and chemokine receptors CCR1 and CCR2; however, in preosteoclasts the expression of chemokine receptors CCR1 and CCR2 was not up-regulated compared to their expression in BMM. However, addition of RANKL to preosteoclasts markedly increased the expression of CCR1. In contrast, expression of macrophage antigen emr-1 (F4/80) and chemokine receptor CCR5 was down-regulated in preosteoclasts. The combination of TNF-α, TGF-β, and M-CSF induced Kat1⁺CD11b⁺ cells, but these cells were also induced by TNF-α alone. In addition, MIP-1α and MCP-1, which are ligands for CCR1 and CCR2, were chemotactic for preosteoclasts, and promoted multinucleation of preosteoclasts. Finally, we found that Kat1⁺c-fms⁺ cells were present in bone tissues of rats with adjuvant arthritis. These data demonstrate that TNF-α in combination with TGF-β efficiently generates preosteoclasts in vitro. We delineated characteristics that are useful for identifying and isolating rat preosteoclasts, and found that CCR1 expression was regulated in the fusion step in osteoclastogenesis.     

GDNF and TGF-β1 promote cell survival in serum-free cultures of primary rat microglia

Recent evidence indicates that glial cell line-derived neurotrophic factor (GDNF) may influence microglial survival, proliferation, and activation, but this has not yet been tested on isolated primary microglia. We compared the effects of individual and combined application of 10 ng/ml GDNF and 1 ng/ml transforming growth factor-beta1 (TGF-beta1) on total cell number, 5-bromo-2'-deoxyuridine (BrdU) incorporation, DNA nick-end labelling (TUNEL staining), and nitrite and lactate dehydrogenase (LDH) secretion in serum-free cultures of primary rat microglia. GDNF as well as TGF-beta1 enhanced the total number of lectin-positive cells and decreased the number of TUNEL-positive nuclei, while no effect on proliferation was observed. Both factors suppressed the secretion of nitrite during the first 4 days of culturing, and GDNF but not TGF-beta1 reduced the secretion of LDH in 2-week-old cultures. These findings suggest that GDNF and TGF-beta1 support survival of primary microglia in vitro.     

Suppression of TNF-α and IL-1 signaling identifies a mechanism of homeostatic regulation of macrophages by IL-27

IL-27 is a pleiotropic cytokine with both activating and inhibitory functions on innate and acquired immunity. IL-27 is expressed at sites of inflammation in cytokine-driven autoimmune/inflammatory diseases, such as rheumatoid arthritis, psoriasis, inflammatory bowel disease, and sarcoidosis. However, its role in modulating disease pathogenesis is still unknown. In this study, we found that IL-27 production is induced by TNF-α in human macrophages (MΦ) and investigated the effects of IL-27 on the responses of primary human MΦ to the endogenous inflammatory cytokines TNF-α and IL-1. In striking contrast to IL-27-mediated augmentation of TLR-induced cytokine production, we found that IL-27 suppressed MΦ responses to TNF-α and IL-1β, thus identifying an anti-inflammatory function of IL-27. IL-27 blocked the proximal steps of TNF-α signaling by downregulating cell-surface expression of the signaling receptors p55 and p75. The mechanism of inhibition of IL-1 signaling was downregulation of the ligand-binding IL-1RI concomitant with increased expression of the receptor antagonist IL-1Ra and the decoy receptor IL-1RII. These findings provide a mechanism for suppressive effects of IL-27 on innate immune cells and suggest that IL-27 regulates inflammation by limiting activation of MΦ by inflammatory cytokines while preserving initial steps in host defense by augmenting responses to microbial products.     

Downregulation of immune response by the human cytokines Interleukin-32α and β in cell-mediated rejection

Xenotransplantation of porcine organs has the potential to help overcome the severe shortage of human tissues and organs available for human transplantation. However, numerous hurdles such as immune-mediated xenograft rejection remain before clinical xenotransplantation.In this study, we elucidated the role of human TNF-α-inducing factor, Interleukin-32 (IL-32), in porcine kidney cells (PK-15) during cell-mediated rejection by examining host cell responses. CD8⁺ and CD4⁺ T cells numbers were reduced in the lymph nodes of PK-15/IL-32β injected mice. CD3⁺ Tcells were in mice injected with control cells but PK-15/IL-32α- and PK-15/IL-32β-injected cell numbers were lower in lymphnodes than un transfected controls. In Mixed lymphocyte reaction cultures, the rates of cell proliferation were increased in both PK-15/IL-32α- and PK-15/IL-32β-injected groups compared to the untransfected control groups. The Stable porcine PK-15 cells expression IL-32α and IL-32β inhibited cytotoxic T lymphocyte (CTLs) after cellular xenograft. Our results suggest that human IL-32α and IL-32β regulates on xenograft rejection in cellular xenotransplantation.     

Fetal concentrations of the growth factors TGF-α and TGF-β1 in relation to normal and restricted fetal growth at term

Transforming growth factor-α (TGF-α) and TGF-β1 are major anti-inflammatory cytokines and substantially contribute to normal pregnancy outcome. TGF-α stimulates placental mitosis, whereas TGF-β1 is a critical regulator of trophoblast invasion and fetal growth. We aimed to study cord blood TGF-α and TGF-β1 concentrations in intrauterine-growth-restricted (IUGR, usually associated with abnormal trophoblast invasion, uteroplacental vascular insufficiency and enhanced inflammation) and appropriate-for-gestational-age-(AGA) pregnancies, and investigate possible correlations of the above concentrations with several demographic parameters of infants at birth. Plasma TGF-α and TGF-β1 concentrations were determined by ELISA in 154 mixed arterio-venous cord blood samples from IUGR (n=50) and AGA (n=104) singleton full-term infants. After controlling for possible confounding factors (gender, birth-weight, gestational age, maternal age and parity), cord blood TGF-α and TGF-β1 concentrations were significantly higher in IUGR than AGA group (b=0.402, SE=0.179, p=0.027 and b=0.152, SE=0.061, p=0.014, respectively). Delivery mode had an effect on cord blood TGF-α and TGF-β1 concentrations, both being elevated in cases of vaginal delivery (b=-0.282, SE=0.117, p=0.018 and b=-0.123, SE=0.059, p=0.038, respectively). In conclusion, higher cord blood TGF-α and TGF-β1 concentrations may represent a compensatory response to the inflammatory process characterizing the IUGR state. Additionally, higher cord blood TGF-β1 concentrations in IUGRs could be attributed to increased shear stress, resulting from abnormal blood flow in IUGR fetal blood vessels. Finally, vaginal delivery-associated cytokine release may account for elevated TGF-α and TGF-β1 concentrations.     

Mapping, expression and regulation of the TRα gene in porcine adipose tissue

Thyroid hormone receptors (TR) are members of the nuclear receptor superfamily. There are at least two TR isoforms, TRα and TRβ. The TRα isoform plays a critical role in mediating the action of thyroid hormone in adipose tissue. We mapped the porcine TRα gene to chromosome 12 p11-p13, by using the ImpRH panel. We examined tissue-localization of TRα and determined expression patterns of TRα in porcine adipose tissue with quantitative real-time PCR. TRα was expressed in all tissues, including heart, liver, spleen, stomach, pancreas, brain, small intestine, skeletal muscle, and subcutaneous adipose tissue. In the adipose tissue, the expression of TRα decreased postnatally. Compared to Yorkshire pigs, Jinhua pigs had significantly lower expression levels of TRα gene in the subcutaneous fat tissue. The expression levels of β2-AR, HSL and ATGL were also significantly lower in Jinhua pigs than in Yorkshire pigs. However, no significant differences in PPARγ and SREBP-1C expression levels were found between Jinhua and Yorkshire pigs. Incubation of porcine adipose tissue explants with high doses of isoproterenol (100 and 1000 nM) significantly increased the expression levels of TRα. We conclude that there is considerable evidence that TRα plays an important role in fat deposition in porcine adipose tissue.     

Antisense oligonucleotides to crabp I and II alter the expression of TGF-β3, RAR-β, and tenascin in primary cultures of embryonic palate cells

Summary The cellular retinoic acid-binding proteins (CRABPs) are thought to modulate the responsiveness of cells to retinoic acid (RA). We have previously shown that primary cultures of murine embryonic palate mesenchymal (MEPM) cells express both CRABP-I and CRABP-II genes and that this expression is regulated by RA and transforming growth factor β (TGF-β). These cells also express high levels of TGF-β3, which is also regulated by RA and TGF-β. We have used an antisense strategy to investigate the role of the CRABPs in retinoid-induced gene expression. Subconfluent cultures of MEPM cells were treated for several days with phosphorothioate modified 18-mer oligonucleotides antisense to CRABP-I or CRABP-II and then with all-trans-retinoic acid at a concentration of 3.3 μM or 0.33 μM for 5 or 22 h. Total RNA was then extracted and the expression of TGF-β3, retinoic acid receptor β (RAR-β), and tenascin was assessed by northern blot analysis. Antisense oligonucleotides to CRABP-I partially inhibited the RA-induced TGF-β3, RAR-β, and tenascin mRNA expression. The corresponding mis-sense oligonucleotides were without effect. Antisense oligonucleotides to CRABP-II also partially inhibited RA-induced expression of these genes. As with the CRABP-I antisense, mis-sense oligonucleotides to CRABP-II had no effect. These data suggest that both CRABPs modulate the responsiveness of MEPM cells to retinoic acid. Inhibition of endogenous CRABP expression renders MEPM cells less responsive to RA with respect to induction of TGF-β3, RAR-β, and tenascin gene expression. These results have important implications for our understanding of the role of the CRABPs in retinoid teratology.     

Decrease of PECAM-1-gene-expression induced by proinflammatory cytokines IFN-γ and IFN-α is reversed by TGF-β in sinusoidal endothelial cells and hepatic mononuclear phagocytes

Background and aim  

The mechanisms of transmigration of inflammatory cells through the sinusoids are still poorly understood. This study aims to identify in vitro conditions (cytokine treatment) which may allow a better understanding of the changes in PECAM (platelet endothelial cell adhesion molecule)-1-gene-expression observed in vivo.     

Immunohistochemistry of IL-1β, IL-6 and TNF-α in spleens of mice treated with gold nanoparticles

Gold nanoparticles (AuNPs) possess considerable biocompatibility and therefore gaining more attention for their biomedical applications. Previous studies have shown the transient increase in pro-inflammatory cytokines expression in different organs of rats and mice exposed to AuNPs. Structural changes in the spleen of mice treated with AuNPs have also been reported. This investigation was aimed to study the immunostaining of IL-1β, IL-6 and TNF-α in mice treated with different sizes of AuNPs. The animals were divided into 7 groups of 4 animals in each group. One group received saline and served as control. Two sets of three groups were treated with 5 nm, 20 nm and 50 nm diameter AuNPs. One set was sacrificed on day 1 and the other on day 7 following the AuNPs injections. Spleens were dissected out and promptly fixed in formalin for 3 days and then processed for IL-1β, IL-6 and TNF-α immunostaining using target-specific antibodies. The immunoreactivities of IL-1β and IL-6 were increased with the increase of AuNP size. The immunostaining of IL-1β in spleen of 20 nm AuNP treated mice was subsequently decreased on day 7 whereas it persisted in 50 nm AuNP group. The increase in the immunoreactivity of IL-6 on day 1 was decreased on day 7 in the spleens of mice treated with 20 nm or 50 nm AuNPs. The immunostaining of TNF-α was found to be negative in all the treatment groups. In conclusion, the size of AuNPs plays an important role in the expression of proinflammatory cytokines in mouse spleen; small size (5 nm) AuNPs caused minimal effect, whereas larger (50 nm) AuNPs produced intense immunostaining.