Lipopolysaccharide from Rhodobacter capsulatus counteracts the effects of toxic lipopolysaccharides and inhibits the release of TNF-α, IL-6, and IL-1β in human whole blood

The outcome of pathological process during sepsis caused by Gram-negative bacteria depends on the reaction of human blood cells to bacterial structural components, lipopolysaccharides (LPS). A general inflammatory response develops due to the increased production of proinflammatory cytokines. One of the current methods of prevention of inflammatory response is the inhibition of LPS binding to cellular receptors. We have studied the efficacy of antagonistic properties of LPS from Rhodobacter capsulatus on the production of TNF-α, IL-6, and IL-1β cytokines induced by toxic LPS from Salmonella typhimurium and Escherichia coli in human whole blood. LPS from R. capsulatus in concentrations of 0.1 and 1 μg/mL did not induce synthesis of TNF-α, IL-6, or IL-1β. Measurements of cytokine levels showed that LPS from R. capsulatus exerted a clear protective effect against toxic LPS. In particular, LPS from R. capsulatus fullly inhibited the production of TNF-α and IL-1β and significantly decreased the IL-6 production induced by LPS from S. typhimurium. Additionally, LPS from R. capsulatus antagonized the effects of LPS from E. coli, fully inhibiting the TNF-α production and decreasing the IL-6 and IL-1β levels by 60% and 70%, respectively. Thus, LPS from R. capsulatus acts as a potent antagonist of cell activation induced by toxic LPS.     

Effects of adiponectin in TNF-α, IL-6, and IL-10 cytokine production from coronary artery disease macrophages

Adiponectin, an adipose tissue secreted protein, exhibits anti-inflammatory and antiatherogenic properties. We examined the effects of the globular and full-length adiponectin on cytokine production in macrophages derived from Coronary Artery Disease (CAD) patients and control individuals. Adiponectin's effects in human macrophages upon lipopolysaccharide (LPS) treatment were also examined. Full length adiponectin acted differently on TNF-α and IL-6 production by upregulating TNF-α and IL-6 protein production, but not their mRNA expression. Additionally, full length adiponectin was unable to abrogate LPS proinflammatory effect in TNF-α and IL-6 mRNA expression in CAD and NON-CAD macrophages. In contrast, globular adiponectin appeared to have proinflammatory properties by potently upregulating TNF-α and IL-6 mRNA and protein secretion in human macrophages while subsequently rendered cells resistant to further proinflammatory stimuli. Moreover, both forms of adiponectin powerfully suppressed scavenger MSR-AI mRNA expression and augmented IL-10 protein release, both occurring independently of the presence of LPS or CAD. These data indicate that adiponectin could potentially protect human macrophages via the elevated IL-10 secretion and the suppression of MSR-AI expression. It can also be protective in CAD patients since the reduced adiponectin-induced IL-6 release in CAD macrophages compared to controls, could be beneficial in the development of inflammation related atherosclerosis.     

Role of proinflammatory cytokines on lipopolysaccharide-induced phase shifts in locomotor activity circadian rhythm

We previously reported that early night peripheral bacterial lipopolysaccharide (LPS) injection produces phase delays in the circadian rhythm of locomotor activity in mice. We now assess the effects of proinflammatory cytokines on circadian physiology, including their role in LPS-induced phase shifts. First, we investigated whether differential systemic induction of classic proinflammatory cytokines could explain the time-specific behavioral effects of peripheral LPS. Induction levels for plasma interleukin (IL)-1α, IL-1β, IL-6, or tumor necrosis factor (TNF)-α did not differ between animals receiving a LPS challenge in the early day or early night. We next tested the in vivo effects of central proinflammatory cytokines on circadian physiology. We found that intracerebroventricular (i.c.v.) delivery of TNF-α or interleukin IL-1β induced phase delays on wheel-running activity rhythms. Furthermore, we analyzed if these cytokines mediate the LPS-induced phase shifts and found that i.c.v. administration of soluble TNF-α receptor (but not an IL-1β antagonistic) prior to LPS stimulation inhibited the phase delays. Our work suggests that the suprachiasmatic nucleus (SCN) responds to central proinflammatory cytokines in vivo, producing phase shifts in locomotor activity rhythms. Moreover, we show that the LPS-induced phase delays are mediated through the action of TNF-α at the central level, and that systemic induction of proinflammatory cytokines might be necessary, but not sufficient, for this behavioral outcome.     

小胶质细胞在脂多糖引起的热高敏中的作用

目的探讨小胶质细胞在脂多糖引起的热高敏中的作用。方法清洁级雄性昆明小鼠,随机分成两组,每组5只,腹腔注射LPS组和注射PBS组,在注射前及后30、60、120、240 min测量小鼠足底的热痛阈;每组于注射前及后4h各处死5只取脑组织检测IL-1β、TNF-α;每组于腹腔注射4h时处死动物,免疫荧光确定脑组织中小胶质细胞的激活情况。然后分为四组,米诺环素+PBS组,米诺环素+LPS组,PBS+PBS组,PBS+LPS组,每组5只,连续三天腹腔注射米诺环素或PBS,第三天注射LPS或PBS,在注射前及后30、60、120、240 min测量小鼠足底的热痛阈;每组于注射前及后4h各处死5只取脑组织检测IL-1β、TNF-α。结果与注射PBS相比,注射LPS导致IL-1β、TNF-α分泌增加,注射60、120、240 min小鼠的热痛阈降低;与米诺环素+PBS组、米诺环素+LPS组、PBS+PBS组相比,PBS+LPS组导致IL-1β、TNF-α分泌增加,注射60、120、240 min小鼠的热痛阈降低。结论LPS激活小胶质细胞分泌促炎细胞因子导致热高敏。     

Pro-inflammatory cytokines downregulate platelet derived growth factor-α receptor gene expression in human osteoblastic cells

Platelet derived growth factor (PDGF) is thought to play a significant role in bone repair and regeneration. We previously demonstrated that PDGF-AA binding can be modulated by interleukin-1 (IL-1). We now report that TNF-α significantly reduces PDGF-AA binding by decreasing the number of PDGF-α receptor subunits on the surface of normal human osteoblastic cells. This inhibition is likely due to a decrease in synthesis of PDGF-α receptors since TNF-α causes a relatively rapid decrease in PDGF-α receptor mRNA levels as determined by Northern blot analysis. The physiologic importance of this inhibition is demonstrated by a TNF-α induced decrease in PDGF-AA stimulated tyrosine kinase activity. When saturating concentrations of TNF-α were used, the addition of IL-1 further inhibited PDGF-AA binding and further decreased surface expression of PDGF-α receptors. In contrast, other mediators such as IL-6, PTH, 1,25(OH)₂ vit D₃, hydrocortisone, PGE₂, bFGF, and IGF-1 had no effect. These results suggest that binding to the PDGF-α receptor is decreased by the strong pro-inflammatory cytokines such as IL-1β and TNF-α rather than as a general response to mediators important in bone resorption or bone formation. TNF-α and IL-1 are often co-expressed during destructive inflammatory processes. Thus, TNF-α and IL-1 may work in concert to limit the response of osteoblastic cells to PDGF-AA during periods of osseous inflammation. © 1996 Wiley-Liss, Inc.     

Activation of the PI3K pathway increases TLR-induced TNF-α and IL-6 but reduces IL-1β production in mast cells

Recognition of bacterial constituents by mast cells (MCs) is dependent on the presence of pattern recognition receptors, such as Toll-like receptors (TLRs). The final cellular response, however, depends on the influence of multiple environmental factors. In the current study we tested the hypothesis that the PI3K-activating ligands insulin-like growth factor-1 (IGF-1), insulin, antigen, and Steel Factor (SF) are able to modulate the TLR4-mediated production of proinflammatory cytokines in murine MCs. Costimulation with any of these ligands caused increased LPS-triggered secretion of IL-6 and TNF-α, but attenuated the production of IL-1β, though all three cytokines were produced in an NFκB-dependent manner. The pan-specific PI3K-inhibitor Wortmannin reverted the altered production of these cytokines. In agreement, MCs deficient for SHIP1, a negative regulator of the PI3K pathway, showed augmented secretion of IL-6/TNF-α and reduced production of IL-1β in response to LPS alone. The differential effects of IGF-1 on TLR4-mediated cytokine production were also observed in the context of TLR2 and IL-33 receptor-mediated MC activation. Importantly, these effects were seen in both bone marrow-derived and peritoneal MCs, suggesting general relevance for MCs. Using pharmacological and genetic tools, we could show that the p110δ isoform of PI3K is strongly implicated in SF-triggered suppression of LPS-induced IL-1β production. Costimulation with antigen was affected to a lesser extent. In conclusion, NFκB-dependent production of proinflammatory cytokines in MCs is differentially controlled by PI3K-activating ligand/receptor systems.     

Cytokine single nucleotide polymorphisms in patients’ with gallstone: dose TGF-β gene variants affect gallstone formation?

Gallstone is a common biliary disorder with several risk factors. Immune responses and inflammatory cytokines are important in this disease; as a result, some cytokines can be detected in bile fluid. In this research, cytokine gene polymorphisms were studied, and their effects on gallstone formation were evaluated. On 158 gallstone patients and 254 normal subjects, by PCR- RFLP method, IL-4-C590T polymorphism and by ARMS-PCR method, IFN-γ T+874A, TNF-α-A308G, IL-6 G-174C and TGF-β T+869C variants were studied. Pathologic evaluations were done on surgical specimens. There were no significant differences in distribution of evaluated polymorphisms between patient group and normal control group (P > 0.05), except TGF-β +869T allele (P = 0.04, OR = 1.23, 95 % CI = 1–1.79) which was higher in patients with gallstone. Although the pro-inflammatory cytokines such as TNF-α and IL-6 may promote gallstone formation, in this study no significant correlation between TNF-α and IL-6 polymorphisms and gallstone formation was seen. It is taught that TGF-β may affect gallbladder cells to promote gallstone formation and higher producer TGF-β +869T allele can be a risk factor of gallstone disease, so further studies would be more elucidative.     

Role of Proinflammatory Cytokines on Lipopolysaccharide-Induced Phase Shifts in Locomotor Activity Circadian Rhythm

We previously reported that early night peripheral bacterial lipopolysaccharide (LPS) injection produces phase delays in the circadian rhythm of locomotor activity in mice. We now assess the effects of proinflammatory cytokines on circadian physiology, including their role in LPS-induced phase shifts. First, we investigated whether differential systemic induction of classic proinflammatory cytokines could explain the time-specific behavioral effects of peripheral LPS. Induction levels for plasma interleukin (IL)-1α, IL-1β, IL-6, or tumor necrosis factor (TNF)-α did not differ between animals receiving a LPS challenge in the early day or early night. We next tested the in vivo effects of central proinflammatory cytokines on circadian physiology. We found that intracerebroventricular (i.c.v.) delivery of TNF-α or interleukin IL-1β induced phase delays on wheel-running activity rhythms. Furthermore, we analyzed if these cytokines mediate the LPS-induced phase shifts and found that i.c.v. administration of soluble TNF-α receptor (but not an IL-1β antagonistic) prior to LPS stimulation inhibited the phase delays. Our work suggests that the suprachiasmatic nucleus (SCN) responds to central proinflammatory cytokines in vivo, producing phase shifts in locomotor activity rhythms. Moreover, we show that the LPS-induced phase delays are mediated through the action of TNF-α at the central level, and that systemic induction of proinflammatory cytokines might be necessary, but not sufficient, for this behavioral outcome. (Author correspondence: dgolombek@unq.edu.ar)     

Calcitriol downregulates TNF-α and IL-6 expression in cultured placental cells from preeclamptic women

Placenta is an important source and target of hormones that contribute to immunological tolerance and maintenance of pregnancy. In preeclampsia (PE), placental calcitriol synthesis is low; whereas pro-inflammatory cytokines levels are increased, threatening pregnancy outcome. Previously, we showed that calcitriol inhibits Th-1 cytokines under experimental inflammatory conditions in normal trophoblasts. However, a study of the regulation of inflammatory cytokines by calcitriol in trophoblasts from a natural inflammatory condition, such as PE, is still lacking. Therefore, the aim of the present study was to investigate calcitriol effects upon TNF-α, IFN-γ, IL-6 and IL-1β in cultured placental cells from preeclamptic women by using qPCR and ELISA. Placentas were collected after cesarean section from preeclamptic women and enriched trophoblastic preparations were cultured in the absence or presence of different calcitriol concentrations during 24 h. In these cell cultures, pro-inflammatory cytokines TNF-α and IL-6 secretion and mRNA expression were downregulated by calcitriol (P < 0.05). No significant effects of calcitriol upon IFN-γ and IL-1β were observed. In addition, basal expression of TNF-α, IL-6 and IL-1β decreased as the cells formed syncytia. Our study supports an important autocrine/paracrine role of placental calcitriol in controlling adverse immunological responses at the feto–maternal interface, particularly in gestational pathologies associated with exacerbated inflammatory responses such as preeclampsia.     

γ-Tocotrienol inhibits lipopolysaccharide-induced interlukin-6 and granulocyte colony-stimulating factor by suppressing C/EBPβ and NF-κB in macrophages

Cytokines generated from macrophages contribute to pathogenesis of inflammation-associated diseases. Here we show that γ-tocotrienol (γ-TE), a natural vitamin E form, inhibits lipopolysaccharide (LPS)-induced interleukin (IL)-6 production without affecting tumor necrosis factor α (TNF-α), IL-10 or cyclooxygenase-2 (COX-2) up-regulation in murine RAW264.7 macrophages. Mechanistic studies indicate that nuclear factor κB (NF-κB), but not c-Jun NH(2)-terminal protein kinase, p38 or extracellular signal-regulated kinase mitogen-activated protein kinases (MAPKs), is important to IL-6 production and that γ-TE treatment blocks NF-κB activation. In contrast, COX-2 appears to be regulated by p38 MAPK in RAW cells, but γ-TE has no effect on LPS-stimulated p38 phosphorylation. Despite necessary for IL-6, NF-κB activation by TNF-α or other cytokines is not sufficient for IL-6 induction with exception of LPS. CCAAT/enhancer-binding protein (C/EBP) β appears to be involved in IL-6 formation because LPS induces C/EBPβ up-regulation, which parallels IL-6 production, and knockdown of C/EBPβ with small interfering RNA results in diminished IL-6. LPS but not individual cytokines is capable of stimulating C/EBPβ and IL-6 in macrophages. Consistent with its dampening effect on IL-6, γ-TE blunts LPS-induced up-regulation of C/EBPβ without affecting C/EBPδ. γ-TE also decreases LPS-stimulated granulocyte colony-stimulating factor (G-CSF), a C/EBPβ target gene. Compared with RAW264.7 cells, γ-TE shows similar or stronger inhibitory effects on LPS-triggered activation of NF-κB, C/EPBβ and C/EBPδ and more potently suppresses IL-6 and G-CSF in bone marrow-derived macrophages. Our study demonstrates that γ-TE has antiinflammatory activities by inhibition of NF-κB and C/EBPs activation in macrophages.     

Key role of regulated upon activation normal T-cell expressed and secreted, nonstructural protein1 and myeloperoxidase in cytokine storm induced by influenza virus PR-8 (A/H1N1) infection in A549 bronchial epithelial cells

Influenza virus infection causes severe respiratory disease such as that due to avian influenza (H5N1). Influenza A viruses proliferate in human epithelial cells, which produce inflammatory cytokines/chemokines as a "cytokine storm" attenuated with the viral nonstructural protein 1 (NS1). Cytokine/chemokine production in A549 epithelial cells infected with influenza A/H1N1 virus (PR-8) or nonstructural protein 1 (NS1) plasmid was examined in vitro. Because tumor necrosis factor-α (TNF-α) and regulated upon activation normal T-cell expressed and secreted (RANTES) are predominantly produced from cells infected with PR-8 virus, the effects of mRNA knockdown of these cytokines were investigated. Small interfering (si)TNF-α down-regulated RANTES expression and secretion of RANTES, interleukin (IL)-8, and monocyte chemotactic protein-1 (MCP-1). In addition, siRANTES suppressed interferon (IFN)-γ expression and secretion of RANTES, IL-8, and MCP-1, suggesting that TNF-α stimulates production of RANTES, IL-8, MCP-1, and IFN-γ, and RANTES also increased IL-8, MCP-1, and IFN-γ. Furthermore, administration of TNF-α promoted increased secretion of RANTES, IL-8, and MCP-1. Administration of RANTES enhanced IL-6, IL-8, and MCP-1 production without PR-8 infection. These results strongly suggest that, as an initial step, TNF-α regulates RANTES production, followed by increase of IL-6, IL-8, and MCP-1 and IFNs concentrations. At a later stage, cells transfected with viral NS1 plasmid showed production of a large amount of IL-8 and MCP-1 in the presence of the H(2)O(2)-myeloperoxidse (MPO) system, suggesting that NS1 of PR-8 may induce a "cytokine storm" from epithelial cells in the presence of an H(2)O(2)-MPO system.     

Modulation of cytokine production by monocytes and developing-dendritic cells under the influence of leukemia and lymphoma cell products

Cytokines and other soluble factors released by tumor cells play an important role in modulating immune cells to favor tumor development. Monocyte differentiation into macrophages or dendritic cells (DCs) with specific phenotypes is deeply affected by tumor signals and understanding this context is paramount to prevent and propose new therapeutic possibilities. Hence, we developed a study to better describe the modulatory effects of leukemia and lymphoma cell products on human monocytes and monocyte-derived DCs secretion of cytokines such as interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, and IL-12. Except with the promyelocytic leukemia cell supernatants (HL-60), the other two tumor supernatants (chronic myeloid leukemia, K562 and Burkitt lymphoma, DAUDI) increased both TNF-α and IL-1β production by monocytes and monocytes undergoing differentiation. This effect was neither explained by alterations of cell number in culture nor by the high amount of vascular endothelial growth factor (VEGF) present in the tumor supernatants. Moreover, all supernatants used were able to induce drastic reduction of IL-12 secretion by cells induced to activation, suggesting a negative interference with Th1 antitumoral responses that should be a huge advantage for tumor progression.