Tumor necrosis factor receptor family costimulation increases regulatory T-cell activation and function via NF-κB

Several drugs targeting members of the TNF superfamily or TNF receptor superfamily (TNFRSF) are widely used in medicine or are currently being tested in therapeutic trials. However, their mechanism of action remains poorly understood. Here, we explored the effects of TNFRSF co-stimulation on murine Foxp3⁺ regulatory T cell (Treg) biology, as they are pivotal modulators of immune responses. We show that engagement of TNFR2, 4-1BB, GITR, and DR3, but not OX40, increases Treg proliferation and survival. Triggering these TNFRSF in Tregs induces similar changes in gene expression patterns, suggesting that they engage common signal transduction pathways. Among them, we identified a major role of canonical NF-κB. Importantly, TNFRSF co-stimulation improves the ability of Tregs to suppress colitis. Our data demonstrate that stimulation of discrete TNFRSF members enhances Treg activation and function through a shared mechanism. Consequently, therapeutic effects of drugs targeting TNFRSF or their ligands may be mediated by their effect on Tregs.     

LPS induces GROα chemokine production via NF-κB in oral fibroblasts

Objective and design  

Chemotaxis of neutrophils from blood to the inflammation process plays an important role in development of periodontal inflammation. The novel chemokine GROα, also named CXCL1, is a strong chemoattractant for neutrophils. Data on production and regulation of GROα by oral fibroblasts have not previously been presented.     

Recombinant murine cytomegalovirus vector activates human monocyte-derived dendritic cells in a NF-κB dependent pathway

To evaluate the potential use of recombinant murine cytomegalovirus (MCMV) as an antigen delivery vector, we examined the cytokine and CD80 and CD86 expression profiles of MCMV encoding either enhanced green fluorescent protein gene (MCMV-EGFP) or human immunodeficiency virus-1 glycoprotein gp120 gene (MCMV-gp120) infected monocyte-derived dendritic cells (Mo-DC) and investigated the role of nuclear factor kappa B (NF-κB) in Mo-DC activation. Results showed that MCMV triggered the induction of inflammatory cytokines and/or CD80 and CD86 up-regulation in Mo-DC. UV-inactivated MCMV exhibited a reduced production of inflammatory cytokines and a lowered expression of CD80 and CD86 compared with live MCMV infection. Treatment of cells with a NF-κB peptide inhibitor prior to MCMV infection reduced the induction of cytokines and CD80 and CD86 up-regulation. Overall, the results suggest that recombinant MCMV vectors activate human Mo-DC in a NF-κB dependent pathway. The abortive infection or de novo gene expression greatly enhances the activation of Mo-DC by MCMV vectors.     

Anti-inflammatory effects of galangin on lipopolysaccharide-activated macrophages via ERK and NF-κB pathway regulation

Inflammation is the major symptom of the innate immune response to microbial infection. Macrophages, immune response-related cells, play a role in the inflammatory response. Galangin is a member of the flavonols and is found in Alpinia officinarum, galangal root and propolis. Previous studies have demonstrated that galangin has antioxidant, anticancer, and antineoplastic activities. However, the anti-inflammatory effects of galangin are still unknown. In this study, we investigated the anti-inflammatory effects of galangin on RAW 264.7 murine macrophages. Galagin was not cytotoxic to RAW 264.7 cells, and nitric oxide (NO) production induced by lipopolysaccharide (LPS)-stimulated macrophages was significantly decreased by the addition of 50?μM galangin. Moreover, galangin treatment reduced mRNA levels of cytokines, including IL-1β and IL-6, and proinflammatory genes, such as iNOS in LPS-activated macrophages in a dose-dependent manner. Galangin treatment also decreased the protein expression levels of iNOS in activated macrophages. Galangin was found to elicit anti-inflammatory effects by inhibiting ERK and NF-κB-p65 phosphorylation. In addition, galangin-inhibited IL-1β production in LPS-activated macrophages. These results suggest that galangin elicits anti-inflammatory effects on LPS-activated macrophages via the inhibition of ERK, NF-κB-p65 and proinflammatory gene expression.     

Chikusetsusaponin V inhibits inflammatory responses via NF-κB and MAPK signaling pathways in LPS-induced RAW 264.7 macrophages

Excessive activation of macrophages is implicated in various inflammation resulted injuries. Saponins from Panax japonicus (SPJ) have been shown to possess anti-inflammatory activities. However, whether Chikusetsusaponin V (CsV), the most abundant component of SPJ, can exert anti-inflammatory activities is unknown. The present study was aimed to investigate the anti-inflammatory effects of CsV in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells and the underlying mechanisms. Our data showed that CsV dose-dependently inhibited NO, iNOS, TNF-α and IL-1β expressions in LPS-stimulated RAW264.7 cells. Increased protein levels of nuclear NF-κB and elevated phosphorylation levels of ERK and JNK in LPS-stimulated RAW 264.7 cells were also found downregulated by CsV treatment. Furthermore, the increase of CD14 and TLR4 mRNA expression due to LPS stimulation were significantly reversed by CsV treatment. These results suggested that CsV attenuated LPS-induced inflammatory responses partly via TLR4/CD14-mediated NF-κB and MAPK pathways.     

Nicorandil modulated macrophages activation and polarization via NF-κb signaling pathway

Nicorandil, a drug with both nitrate-like and ATP-sensitive potassium (K_ATP) channel-activating properties, has been well demonstrated in various aspects of myocardial infarction (MI), especially in inhibiting cell apoptosis and increasing coronary flow. However, the role of nicorandil in regulating inflammation and angiogenesis following myocardial infarction is still unrevealed. In the present study, we explored the effect of nicorandil on macrophage phenotype transition and inflammation regulation and the potential underlying mechanisms. For the phenotype transition and phagocytosis ability of macrophages detection, flow cytometry analysis was used. The inflammation factors were measured with ELISA and qRT-PCR. Western blot was used to assess the levels of NF-κb and its target genes and VEGF expression. The tube formation ability of endothelial cells was examined on matrigel. We discovered that nicorandil can obviously inhibit the differentiation of monocytes into mature macrophages and decrease M1 phenotype transition both in peritoneal macrophages and cultured macrophage cell line in normal or hypoxia and serum deprivation (H/SD) conditions. Meanwhile, nicorandil can induce an anti-inflammatory M2 phenotype. Thereby, nicorandil regulated macrophages switching to M1/M2 status. Our data further showed that NF-κb and the expression of its target genes were pivotal players in the regulation of macrophages phenotype. Besides, we also showed that nicorandil can promote the tube formation and VEGF expression in endothelial cells. We concluded that nicorandil may serve as an effective modulator of NF-κb signaling pathway during the pathogenesis of MI via regulating M1/M2 status and promoting angiogenesis.     

Deficiency of inflammation-sensing protein neuropilin-2 in myeloid-derived macrophages exacerbates colitis via NF-κB activation

Neuropilin-2 (NRP2) is a multifunctional protein engaged in the regulation of angiogenesis, lymphangiogenesis, axon guidance, and tumor metastasis, but its function in colitis remains unclear. Here, we found that NRP2 was an inflammation-sensing protein rapidly and dramatically induced in myeloid cells, especially in macrophages, under inflammatory contexts. NRP2 deficiency in myeloid cells exacerbated dextran sulfate sodium salt-induced experimental colitis by promoting polarization of M1 macrophages and colon injury. Mechanistically, NRP2 could be induced via NF-κB activation by TNF-α in macrophages, but exerted an inhibitory effect on NF-κB signaling, forming a negative feedback loop with NF-κB to sense and alleviate inflammation. Deletion of NRP2 in macrophages broke this negative feedback circuit, leading to NF-κB overactivation, inflammatory exacerbation, and more severe colitis. Collectively, these findings reveal inflammation restriction as a role for NRP2 in macrophages under inflammation contexts and suggest that NRP2 in macrophages may relieve inflammation in inflammatory bowel disease. © 2023 The Pathological Society of Great Britain and Ireland.     

Pneumocystis carinii stimulates in vitro production of tumor necrosis factor-α by human macrophages

The ability of Pneumocystis carinii to induce tumor necrosis factor (TNF)- release by monocytes/macrophages from immunocompetent humans was investigated. Monocytes and monocyte-derived macrophages from healthy individuals produced an increased amount of TNF- when exposed to P. carinii cysts obtained from rats with steroid-induced pneumocystosis. The cysts induced increased TNF- production in a dose-dependent manner; baseline TNF- production was restored after addition of an anti-P. carinii hyperimmune serum. Kinetics experiments showed that the secretion of TNF- occurs early and reachs a maximal peak after 8 h. Since TNF- is directly lethal to P. carinii in vitro, it is suggested that the production of this cytokine in response to the cysts may be one of the mechanisms for the control of this parasitic infection.     

Angiotensin II induces tumor necrosis factor-α expression and release from cultured human podocytes

Objective  

High levels of both angiotensin (Ang) II and tumor necrosis factor (TNF)-α have been implicated in the pathogenesis of glomerular injury by affecting podocytes. The aim of this study was to investigate the Ang II–TNF-α relationship in human podocytes.     

The role of B7 family costimulatory molecules and indoleamine 2,3-dioxygenase in primary Sjögren’s syndrome and systemic sclerosis

B7 costimulatory molecules are present on antigen-presenting cells (APCs) and influence intracellular expression of indoleamine 2,3-dioxygenase (IDO), a molecule with important immunoregulatory functions. We determined the frequency of activated (CD11b+) monocytes expressing B7-1, B7-2, B7-H1, and B7-H2 molecules, and that of CD3+ and CD4+ T cells expressing the corresponding CD28, CTLA-4, PD-1, and ICOS receptors in peripheral blood samples of 20 healthy adults and 9 SSc and 15 pSS patients using flow cytometry. We also examined the intracellular expression of IDO. The expression of CD28 was lower in both SSc and pSS patients. The frequency of CTLA-4 was increased in pSS. The expression of ICOS, a stimulator of T cell activation, was elevated in pSS, but not in SSc, while that of its corresponding costimulatory molecule, B7-H2, was strongly decreased in SSc compared to controls. The frequency of PD-1 expressing T lymphocytes was decreased in both pSS and SSc. The frequency of IDO-expressing APCs, as well as intracellular IDO content in T cells was higher in pSS than in controls. Our investigation identified a number of differences in B7 costimulation between SSc and pSS patients which may play a role in the distinct pathogenesis and clinical features of these autoimmune disorders.     

Clusterin induces matrix metalloproteinase-9 expression via ERK1/2 and PI3K/Akt/NF-κB pathways in monocytes/macrophages

Most solid tumor tissues possess a significant population of macrophages, which are known to be closely linked with tumor progression and metastasis. Clusterin has been reported to be overexpressed in various tumors and to have a tumor-promoting role. As clusterin induction and macrophage infiltration occur concurrently at the tumor site, it raises a possibility that clusterin may regulate the function of macrophages via facilitating ECM remodeling. Here, we demonstrate for the first time the expression of MMP-9 by clusterin in human primary monocytes as well as human and murine macrophage cell lines, THP-1, and Raw264.7. MMP-9 expression was accompanied by increased enzymatic activity, as revealed by gelatin zymography. The MMP-9 activity promoted by clusterin was found to be dependent on the activation of ERK1/2 and PI3K/Akt but not p38 or JNK pathways. Inhibition of PI3K activity did not affect the activation of ERK1/2 and vice versa, indicating that the two pathways were independently operated to stimulate MMP-9 activity. Moreover, clusterin facilitated nuclear translocation of NF-κB p65 along with IκB-α degradation and phosphorylation, which was critical for MMP-9 expression. As NF-κB is a central regulator of inflammation, clusterin may provide a molecular link between inflammation and cancer via up-regulating NF-κB and MMP-9. Collectively, these data highlight a novel role of clusterin as a stimulator for MMP-9 expression in macrophages, which may contribute to the tissue reorganization by serving as a modulator for ECM degradation.     

Delta-9-tetrahydrocannabinol suppresses tumor necrosis factor α maturation and secretion but not its transcription in mouse macrophages

Various in vitro studies have shown that delta-9-tetrahydrocannabinol (THC), the major psychoactive component of marijuana, has a variety of inhibitory effects on immune functions including effects on macrophages. The present studies have examined the mechanism of THC's effects on tumor necrosis factor α (TNF-α), a major macrophage-produced cytokine and an important mediator involved in cytokine networks and in host defense mechanisms. Exposure of macrophages to medium containing THC has resulted in low levels of soluble TNF-α protein and reduced TNF-α bioactivity in the culture supernatant. However, THC did not inhibit the levels of LPS-induced TNF-α mRNA and intracellular TNF-α precursor protein, had only a weak effect on expression of membrane-bound TNF-α, but suppressed TNF-α maturation/secretion by macrophages. The higher the THC concentration in the medium during TNF-α induction, the greater the amount of intracellular TNF-α precursors that accumulated in the activated macrophages and the less mature TNF-α was released from the cells. Data suggest that TNF-α production by macrophages was altered greatly by exposure to THC at the levels of TNF-α precursor maturation and secretion.     

Chondroitin-6-sulfate attenuates inflammatory responses in murine macrophages via suppression of NF-κB nuclear translocation

Inflammation is a host protective response to noxious stimuli, and excessive production of pro-inflammatory mediators by macrophages (mφ) can lead to numerous pathological conditions. In this study, immunomodulatory effects of immobilized and soluble glycosaminoglycans (GAGs) on mouse-bone-marrow-derived mφ were compared by measuring nitric oxide (NO). We demonstrate here that all GAGs studied except for heparin were able to modulate interferon-γ/lipopolysaccharide (IFN-γ/LPS)-induced NO release by mφ to varying extents after 24 h of incubation. In particular, the modulatory activities of soluble chondroitin-6-sulfate (C6S), hyaluronic acid and heparan sulfate altered markedly after covalent immobilization. Of these, soluble C6S exhibited the strongest NO inhibitory activity, and the inhibition was dose- and time-dependent. Moreover, C6S significantly reduced pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α production by IFN-γ/LPS- or LPS-activated mφ. Specifically, the C6S-mediated suppression of mφ pro-inflammatory phenotype was accompanied by an increase in the IL-10 level, suggesting a possible switch towards anti-inflammatory/wound healing M2 state. In addition, the highest magnitude of inhibitory effects was obtained when cells were pre-treated with C6S prior to IFN-γ/LPS or LPS challenge, suggesting an additional role for C6S in protection against microbial infection. Further investigations reveal that the anti-inflammatory effects of C6S on activated mφ may be ascribed at least in part to suppression of NF-κB nuclear translocation.     

Recombinant TB10.4 of Mycobacterium bovis induces cytokine production in RAW264.7 macrophages through activation of the MAPK and NF-κB pathways via TLR2

The TB10.4 antigen of Mycobacterium bovis/Mycobacterium tuberculosis induces a strong Th1 CD4+ T-cell response. Thus, it is currently under intensive study as a possible vaccine candidate. However, how TB10.4 activates innate immune cells is unclear. How TB10.4 interacts with toll-like receptors (TLRs) and signaling pathways responsible for active inflammation have also not been fully elucidated. Here, as stimulated RAW264.7 cells with recombinant TB10.4 (rTB10.4), derived from M. bovis, increased TNF-α, IL-6 and IL-12 p40 secretin in a dose-dependent manner. Blocking assays showed that TLR2-, but not TLR4-neutralizing antibody reduced expression of TNF-α, IL-6 and IL-12 p40 in RAW264.7 cells. rTB10.4 stimulation activated p38 kinase (p38) and extracellular-regulated kinase (ERK) was TLR2-dependent, whereas inhibition of p38 and ERK activity significantly reduced TNF-α, IL-6 and IL-12 p40 production. Furthermore, rTB10.4 stimulation of RAW264.7 cells resulted in TLR2-mediated activation of NF-κB and induced translocation of NF-κB p65 from the cytoplasm to the nucleus via IκBα degradation. rTB10.4-induced TNF-α, IL-6 and IL-12 p40 release was attenuated by the specific IκB phosphorylation inhibitor, BAY 11-7082. These findings indicate that the M. bovis-derived rTB10.4 induced production of TNF-α, IL-6 and IL-12 p40 involves p38, ERK and NF-κB via the TLR2 pathway.     

Synthesis of tumor necrosis factor α (TNF-α) by human monocytes in vitro

Research Institute of Hematology and Blood Transfusion, Ministry of Health of the Belorussian SSR, Minsk. Institute of Experimental Hematology and Biotechnology, All-Union Hematologic Scientific Center, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR E. A. Zotikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 9, pp. 287–289, September, 1991.