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Wolf AJ. Peptidoglycan-induced modulation of metabolic and inflammatory responses. IMMUNOMETABOLISM (COBHAM, SURREY) 2023; 5:e00024. [PMID: 37128291 PMCID: PMC10144284 DOI: 10.1097/in9.0000000000000024] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 04/06/2023] [Indexed: 05/03/2023]
Abstract
Bacterial cell wall peptidoglycan is composed of innate immune ligands and, due to its important structural role, also regulates access to many other innate immune ligands contained within the bacteria. There is a growing body of literature demonstrating how innate immune recognition impacts the metabolic functions of immune cells and how metabolic changes are not only important to inflammatory responses but are often essential. Peptidoglycan is primarily sensed in the context of the whole bacteria during lysosomal degradation; consequently, the innate immune receptors for peptidoglycan are primarily intracellular cytosolic innate immune sensors. However, during bacterial growth, peptidoglycan fragments are shed and can be found in the bloodstream of humans and mice, not only during infection but also derived from the abundant bacterial component of the gut microbiota. These peptidoglycan fragments influence cells throughout the body and are important for regulating inflammation and whole-body metabolic function. Therefore, it is important to understand how peptidoglycan-induced signals in innate immune cells and cells throughout the body interact to regulate how the body responds to both pathogenic and nonpathogenic bacteria. This mini-review will highlight key research regarding how cellular metabolism shifts in response to peptidoglycan and how systemic peptidoglycan sensing impacts whole-body metabolic function.
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Affiliation(s)
- Andrea J. Wolf
- The Karsh Division of Gastroenterology and Hepatology, F. Widjaja Foundation Inflammatory Bowel Disease Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Research Division of Immunology, Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, USA
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Mycotoxin Zearalenone Attenuates Innate Immune Responses and Suppresses NLRP3 Inflammasome Activation in LPS-Activated Macrophages. Toxins (Basel) 2021; 13:toxins13090593. [PMID: 34564598 PMCID: PMC8473227 DOI: 10.3390/toxins13090593] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/20/2021] [Accepted: 08/22/2021] [Indexed: 01/07/2023] Open
Abstract
Zearalenone (ZEA) is a mycotoxin that has several adverse effects on most mammalian species. However, the effects of ZEA on macrophage-mediated innate immunity during infection have not been examined. In the present study, bacterial lipopolysaccharides (LPS) were used to induce the activation of macrophages and evaluate the effects of ZEA on the inflammatory responses and inflammation-associated signaling pathways. The experimental results indicated that ZEA suppressed LPS-activated inflammatory responses by macrophages including attenuating the production of proinflammatory mediators (nitric oxide (NO) and prostaglandin E2 (PGE2)), decreased the secretion of proinflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6), inhibited the activation of c-Jun amino-terminal kinase (JNK), p38 and nuclear factor-κB (NF-κB) signaling pathways, and repressed the nucleotide-binding and oligomerization domain (NOD)-, leucine-rich repeat (LRR)- and pyrin domain-containing protein 3 (NLRP3) inflammasome activation. These results indicated that mycotoxin ZEA attenuates macrophage-mediated innate immunity upon LPS stimulation, suggesting that the intake of mycotoxin ZEA-contaminated food might result in decreasing innate immunity, which has a higher risk of adverse effects during infection.
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Lambkin-Williams R, Mann A, Shephard A. Inhibition of viral and bacterial trigger-stimulated prostaglandin E 2 by a throat lozenge containing flurbiprofen: An in vitro study using a human respiratory epithelial cell line. SAGE Open Med 2020; 8:2050312120960568. [PMID: 33029351 PMCID: PMC7522825 DOI: 10.1177/2050312120960568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 08/31/2020] [Indexed: 11/22/2022] Open
Abstract
Objectives: Symptoms of sore throat result from oropharyngeal inflammation, for which prostaglandin E2 is a key mediator. Flurbiprofen is a non-steroidal anti-inflammatory that provides sore throat relief. The preliminary objective of this study was to develop an in vitro model for assessing prostaglandin E2 stimulation by viral and bacterial triggers. The primary objective was to investigate the effect of diluted flurbiprofen-containing lozenges on prostaglandin E2 concentrations in stimulated cells. Methods: Prostaglandin E2 production was stimulated in three epithelial cell lines (A549, HEp2, and clonetics bronchial/tracheal epithelial) with influenza A virus (4.5 log10 tissue culture infectious dose50/mL), or bacterial lipopolysaccharide (10µ g/mL) and peptidoglycan (3µ g/mL) and incubated overnight. Prostaglandin E2 levels were assessed by enzyme-linked immunosorbent assay up to 24 h after stimulation. The effect of flurbiprofen 8.75 mg lozenges (diluted to 0.44 mg/mL) on PGE2 production in stimulated cells was assessed in parallel; prior to viral/LPS/PEP stimulation of cells, 300 μL of test product or control was added and incubated for 30 s, 2 and 5 min (and 10 min for bacterial trigger). Prostaglandin E2 levels were measured following stimulation. Results: Viral and lipopolysaccharide/peptidoglycan infection did not consistently stimulate HEp2 cells and bronchial/tracheal epithelial cells to produce prostaglandin E2. Influenza virus, and lipopolysaccharide/peptidoglycan stimulated high prostaglandin E2 concentrations in A549: mean prostaglandin E2 concentration 106.48 pg/mL with viral stimulation vs 33.82 pg/mL for uninfected cells; 83.84 pg/mL with lipopolysaccharide/peptidoglycan vs 71.96 pg/mL for uninfected cells. Flurbiprofen produced significant reductions in virus-stimulated prostaglandin E2 vs stimulated untreated cells at 2 min (p = 0.03). Flurbiprofen produced significant reductions in lipopolysaccharide/peptidoglycan-stimulated prostaglandin E2 concentrations from 30 s (p = 0.02), and at 2, 5 and 10 min (all p < 0.005) vs stimulated untreated cells. Conclusions: A549 cells provide a suitable model for assessment of prostaglandin E2 stimulation by viral and bacterial triggers. Diluted flurbiprofen-containing lozenges demonstrated rapid anti-inflammatory activity in viral- and lipopolysaccharide/peptidoglycan-stimulated A549 cells.
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Mortensen R, Clemmensen HS, Woodworth JS, Therkelsen ML, Mustafa T, Tonby K, Jenum S, Agger EM, Dyrhol-Riise AM, Andersen P. Cyclooxygenase inhibitors impair CD4 T cell immunity and exacerbate Mycobacterium tuberculosis infection in aerosol-challenged mice. Commun Biol 2019; 2:288. [PMID: 31396568 PMCID: PMC6683187 DOI: 10.1038/s42003-019-0530-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/02/2019] [Indexed: 01/06/2023] Open
Abstract
Tuberculosis, caused by infection with Mycobacterium tuberculosis (Mtb), kills over 1.6 million people each year despite availability of antibiotics. The increase in drug resistant Mtb strains is a major public health emergency and host-directed therapy as adjunct to antibiotic treatment has gained increased interest. Cyclooxygenase inhibitors (COXi) are frequently used drugs to alleviate tuberculosis related symptoms. Mouse studies of acute intravenous Mtb infection have suggested a potential benefit of COXi for host-directed therapy. Here we show that COXi treatment (ibuprofen and celecoxib) is detrimental to Mtb control in different mouse models of respiratory infection. This effect links to impairments of the Type-1 helper (Th1) T-cell response as CD4 T-cells in COXi-treated animals have significantly decreased Th1 differentiation, reduced IFNγ expression and decreased protective capacity upon adoptive transfer. If confirmed in clinical trials, these findings could have major impact on global health and question the use of COXi for host-directed therapy.
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Affiliation(s)
- Rasmus Mortensen
- Department of Infectious Disease Immunology, Statens Serum Institut, 2300 Copenhagen S, Denmark
| | | | - Joshua S. Woodworth
- Department of Infectious Disease Immunology, Statens Serum Institut, 2300 Copenhagen S, Denmark
| | - Marie Louise Therkelsen
- Department of Infectious Disease Immunology, Statens Serum Institut, 2300 Copenhagen S, Denmark
| | - Tehmina Mustafa
- Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen & Department of Thoracic Medicine, Haukeland University Hospital, 5021 Bergen, Norway
| | - Kristian Tonby
- Department of Infectious Diseases, Oslo University Hospital, 0424 Oslo, Norway
| | - Synne Jenum
- Department of Infectious Diseases, Oslo University Hospital, 0424 Oslo, Norway
| | - Else Marie Agger
- Department of Infectious Disease Immunology, Statens Serum Institut, 2300 Copenhagen S, Denmark
| | - Anne Ma Dyrhol-Riise
- Department of Infectious Diseases, Oslo University Hospital, 0424 Oslo, Norway
- Institute of Clinical Medicine, University of Oslo, 0424 Oslo, Norway
- Department of Clinical Science, University of Bergen, 5020 Bergen, Norway
| | - Peter Andersen
- Department of Infectious Disease Immunology, Statens Serum Institut, 2300 Copenhagen S, Denmark
- Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen N, Denmark
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Hung HC, Feng CW, Lin YY, Chen CH, Tsui KH, Chen WF, Pan CY, Sheu JH, Sung CS, Wen ZH. Nucleophosmin modulates the alleviation of atopic dermatitis caused by the marine-derived compound dihydroaustrasulfone alcohol. Exp Mol Med 2018; 50:e446. [PMID: 29504608 PMCID: PMC5903824 DOI: 10.1038/emm.2017.272] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 01/20/2023] Open
Abstract
Atopic dermatitis (AD) is a chronic inflammatory skin disease, and its prevalence is increasing. AD usually elicits skin barrier dysfunction, dry skin and itching. As the mechanisms of AD remain unknown, there is an urgent need to find effective therapies. Because of the diversity and complexity of marine environments, the discovery of drugs from marine organisms as novel therapeutic agents for human diseases has seen renewed interest. Dihydroaustrasulfone alcohol (WA-25), the synthetic precursor of austrasulfone, which is a natural product isolated from a Formosan soft coral, has been shown to possess many therapeutic effects in our previous studies. However, the detailed mechanisms and therapeutic effects of WA-25 on AD are incompletely understood. We performed in vitro and in vivo studies to examine the effects of WA-25 on AD. We showed that WA-25 blocks inflammation and oxidative stress. Simultaneously, we also found that WA-25 reduces the AD scores and AD-induced transepidermal water loss (TEWL), scratching behavior, and alloknesis. WA-25 is more effective in cases of AD than are the drugs that are currently used clinically. Importantly, we also found that when nucleophosmin (NPM) was inhibited or when its expression was reduced, the anti-inflammatory and anti-AD effects of WA-25 were blocked. These data suggest that NPM plays dual roles in inflammation and AD. Overall, these results suggest that WA-25 is a potential anti-inflammatory and AD therapeutic agent that is modulated by NPM.
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Affiliation(s)
- Han-Chun Hung
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan
- Doctoral Degree Program in Marine Biotechnology, Academia Sinica, Taipei, Taiwan
| | - Chien-Wei Feng
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan
- Doctoral Degree Program in Marine Biotechnology, Academia Sinica, Taipei, Taiwan
| | - Yen-You Lin
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Chun-Hong Chen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Kuan-Hao Tsui
- Department of Obstetrics and Gynecology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
- Department of Obstetrics and Gynecology and Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
- Department of Pharmacy and Master Program, College of Pharmacy and Health Care, Tajen University, Pingtung County, Taiwan
| | - Wu-Fu Chen
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
- Department of Neurosurgery, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Chieh-Yu Pan
- Department and Graduate Institute of Aquaculture, National Kaohsiung Marine University, Kaohsiung, Taiwan
| | - Jyh-Horng Sheu
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Chun-Sung Sung
- Department of Anesthesiology, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Zhi-Hong Wen
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
- Marine Biomedical Laboratory and Center for Translational Biopharmaceuticals, Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
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Mao Y, Poschke I, Kiessling R. Tumour-induced immune suppression: role of inflammatory mediators released by myelomonocytic cells. J Intern Med 2014; 276:154-70. [PMID: 24597954 DOI: 10.1111/joim.12229] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Tumour-induced immune dysfunction is a serious challenge to immunotherapy for cancer, and intact adaptive and innate cellular immunity is key to its success. Myelomonocytic cells have a central role in this immune suppression, and tumour-associated macrophages, eosinophils, neutrophils and myeloid-derived suppressor cells have all been shown to be of major importance. These myelomonocytic cells secrete a broad repertoire of inflammatory mediators providing them with powerful tools to inhibit tumour-reactive T cells and natural killer cells; free oxygen radicals including reactive oxygen species and NO, arginase, indoleamine 2,3-dioxygenase, prostaglandins, the pro-inflammatory heterodimer S100A8/9 and cytokines, such as granulocyte-macrophage colony-stimulating factor and transforming growth factor-β, have proven particularly potent in suppressing antitumour cellular immunity. Determining which of these factors prevail in individual cancer patients and designing methods aimed at neutralization or inhibition of their effects on target tissues have the potential to greatly enhance the clinical efficacy of immunotherapy.
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Affiliation(s)
- Y Mao
- Department of Oncology-Pathology, Cancer Center Karolinska, Karolinska Institutet, Stockholm, Sweden
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Jiang Y, Zhang H, Wang Y, Chen M, Ye S, Hou Z, Ren L. Modulation of apoptotic pathways of macrophages by surface-functionalized multi-walled carbon nanotubes. PLoS One 2013; 8:e65756. [PMID: 23755279 PMCID: PMC3675050 DOI: 10.1371/journal.pone.0065756] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/29/2013] [Indexed: 01/22/2023] Open
Abstract
Biomedical applications of carbon nanotubes (CNTs) often involve improving their hydrophilicity and dispersion in biological media by modifying them through noncovalent or covalent functionalization. However, the potential adverse effects of surface-functionalized CNTs have not been well characterized. In this study, we functionalized multi-walled CNTs (MWCNTs) via carboxylation, to produce MWCNTs-COOH, and via poly (ethylene glycol) linking, to produce MWCNTs-PEG. We used these functionalized MWCNTs to study the effect of surface functionalization on MWCNTs-induced toxicity to macrophages, and elucidate the underlying mechanisms of action. Our results revealed that MWCNTs-PEG were less cytotoxic and were associated with less apoptotic cell death of macrophages than MWCNTs-COOH. Additionally, MWCNTs-PEG induced less generation of reactive oxygen species (ROS) involving less activation of NADPH oxidase compared with MWCNTs-COOH, as evidenced by membrane translocation of p47phox and p67phox in macrophages. The less cytotoxic and apoptotic effect of MWCNTs-PEG compared with MWCNTs-COOH resulted from the lower cellular uptake of MWCNTs-PEG, which resulted in less activation of oxidative stress-responsive pathways, such as p38 mitogen-activated protein kinases (MAPK) and nuclear factor (NF)-κB. These results demonstrate that surface functionalization of CNTs may alter ROS-mediated cytotoxic and apoptotic response by modulating apoptotic signaling pathways. Our study thus provides new insights into the molecular basis for the surface properties affecting CNTs toxicity.
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Affiliation(s)
- Yuanqin Jiang
- Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China
- Department of E. N. T., Chenggong Hospital of Xiamen University, the 174 Hospital of People’s Liberation Army, Xianmen, China
| | - Honggang Zhang
- Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China
| | - Yange Wang
- Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China
| | - Min Chen
- Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China
| | - Shefang Ye
- Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China
- * E-mail:
| | - Zhenqing Hou
- Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China
| | - Lei Ren
- Department of Biomaterials, College of Materials, Xiamen University, Xiamen, China
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Zídek Z, Kmoníčková E, Kostecká P, Jansa P. Microfiltration method of removal of bacterial contaminants and their monitoring by nitric oxide and Limulus assays. Nitric Oxide 2012; 28:1-7. [PMID: 22981390 DOI: 10.1016/j.niox.2012.08.078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/09/2012] [Accepted: 08/28/2012] [Indexed: 12/19/2022]
Abstract
Similar to lipopolysaccharide (LPS), a product of Gram-negative bacteria, the signal macromolecules of Gram-positive bacteria lipoteichoic acid (LTA) and peptidoglycan (PGN) possess multiple biological activities. They may be a source of misinterpretation of experimental findings. We have found that not only LPS but also LTA and PGN can be detected by the Limulus amebocyte lysate (LAL) assay. All of them stimulate the high output in vitro nitric oxide (NO) production of in rat peritoneal cells. The onset of the NO enhancement was observed with 25-100pg/ml of LPS and 25-100ng/ml of PGN and LTA. Polymyxin B (PMX), if applied at concentration 10,000-fold higher than that of LPS, can completely inhibit the NO and LAL binding responses of LPS. The NO-stimulatory and LAL-binding properties of LTA and PGN are not eliminated by PMX. Handling of LPS contamination with PMX may be associated with serious problems because it possesses intrinsic biological activity and becomes cytotoxic at concentration >25μg/ml. The present findings suggest a convenient alternative avoiding these issues. As monitored by the NO and LAL assays, even high amounts of LPS as well as PGN and LTA can be removed by molecular mass cutoff microfiltration. All types of the filters (3kDa to 100kDa) are equally effective. It is suggested that the microfiltration procedure may be considered as a preferable, general and easy method of sample decontamination.
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Affiliation(s)
- Zdeněk Zídek
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague 4, Czech Republic.
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Obermajer N, Wong JL, Edwards RP, Odunsi K, Moysich K, Kalinski P. PGE(2)-driven induction and maintenance of cancer-associated myeloid-derived suppressor cells. Immunol Invest 2012; 41:635-57. [PMID: 23017139 DOI: 10.3109/08820139.2012.695417] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Myeloid-derived suppressor cells (MDSCs) are critical mediators of tumor-associated immune suppression, with their numbers and activity strongly increased in most human cancers and animal models. MDSCs suppress anti-tumor immunity through multiple mechanisms, including the manipulation of arginine and tryptophan metabolism by such factors as arginase (Arg), inducible nitric oxide synthase (iNOS/NOS2), and indoleamine-2,3-dioxygenase (IDO). Prostaglandin E(2) (PGE(2)), a mediator of chronic inflammation and tumor progression, has emerged as a key molecule in MDSC biology. PGE(2) promotes MDSC development and their induction by additional factors, directly suppresses T cell immune responses and participates in the induction of other MDSC-associated suppressive factors, including Arg, iNOS and IDO. It further promotes MDSC recruitment to tumor environments through the local induction of CXCL12/SDF-1 and the induction and stabilization of the CXCL12 receptor, CXCR4, on tumor-associated MDSCs. The establishment of a positive feedback loop between PGE(2) and cyclooxygenase 2 (COX-2), the key regulator of PGE(2) synthesis, stabilizes the MDSC phenotype and is required for their suppressive function. The central role of PGE(2) in MDSC biology provides for a feasible target for counteracting MDSC-mediated immune suppression in cancer.
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Affiliation(s)
- Nataša Obermajer
- Department of Biotechnology, Jožef Stefan Institute, University of Ljubljana, Ljubljana, Slovenia
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Pandey RK, Dahiya Y, Sodhi A. Mycobacterium indicus pranii downregulates MMP-9 and iNOS through COX-2 dependent and TNF-α independent pathway in mouse peritoneal macrophages in vitro. Microbes Infect 2011; 14:348-56. [PMID: 22138502 DOI: 10.1016/j.micinf.2011.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/12/2011] [Accepted: 11/10/2011] [Indexed: 01/30/2023]
Abstract
Despite the popular belief that granulomas are innate immune mechanism to restrict mycobacterial growth, evidences suggest that granulomas facilitate growth of Mycobacterium by recruiting large numbers of uninfected macrophages to the site of infection. Matrix metalloproteinase-9 (MMP-9) has been shown to be directly involved in recruitment of macrophages at the site of infection, contributing to nascent granuloma maturation and bacterial growth. In this manuscript it is reported that heat-killed Mycobacterium indicus pranii (MIP) leads to a significant downregulation of MMP-9 in murine peritoneal macrophages in vitro. The downregulation of MMP-9 is mediated through cyclooxygenase-2 (COX-2), but independent of tumor necrosis factor-α (TNF-α). By limiting nuclear to cytoplasmic export of COX-2 and iNOS transcripts, MIP inhibits excessively-high levels of nitric oxide which can be damaging to the host during acute phases of infection. MIP has been shown to provide clinical improvement in all phases of leprosy and used for treatment of leprosy and tuberculosis.
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Dahiya Y, Pandey RK, Sodhi A. Nod2 downregulates TLR2/1 mediated IL1β gene expression in mouse peritoneal macrophages. PLoS One 2011; 6:e27828. [PMID: 22114704 PMCID: PMC3219683 DOI: 10.1371/journal.pone.0027828] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 10/26/2011] [Indexed: 12/22/2022] Open
Abstract
Nod2 is a cytosolic pattern recognition receptor. It has been implicated in many inflammatory conditions. Its signaling has been suggested to modulate TLR responses in a variety of ways, yet little is known about the mechanistic details of the process. We show in this study that Nod2 knockdown mouse peritoneal macrophages secrete more IL1β than normal macrophages when stimulated with peptidoglycan (PGN). Muramyl dipeptide (MDP, a Nod2 ligand) + PGN co-stimulated macrophages have lower expression of IL1β than PGN (TLR2/1 ligand) stimulated macrophages. MDP co-stimulation have similar effects on Pam3CSK4 (synthetic TLR2/1 ligand) mediated IL1β expression suggesting that MDP mediated down regulating effects are receptor dependent and ligand independent. MDP mediated down regulation was specific for TLR2/1 signaling as MDP does not affect LPS (TLR4 ligand) or zymosan A (TLR2/6 ligand) mediated IL1β expression. Mechanistically, MDP exerts its down regulating effects by lowering PGN/Pam3CSK4 mediated nuclear cRel levels. Lower nuclear cRel level were observed to be because of enhanced transporting back rather than reduced nuclear translocation of cRel in MDP + PGN stimulated macrophages. These results demonstrate that Nod2 and TLR2/1 signaling pathways are independent and do not interact at the level of MAPK or NF-κB activation.
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Affiliation(s)
- Yogesh Dahiya
- School of Biotechnology, Faculty of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Rajeev Kumar Pandey
- School of Biotechnology, Faculty of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Ajit Sodhi
- School of Biotechnology, Faculty of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
- * E-mail:
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