Differential remodeling of the electron transport chain is required to support TLR3 and TLR4 signaling and cytokine production in macrophages

AbstractIncreasing evidence suggests that mitochondria play a critical role in driving innate immune responses against bacteria and viruses. However, it is unclear if differential reprogramming of mitochondrial function contributes to the fine tuning of pathogen specific immune responses. Here, we found that TLR3 and TLR4 engagement on murine bone marrow derived macrophages was associated with differential remodeling of electron transport chain complex expression. This remodeling was associated with differential accumulation of mitochondrial and cytosolic ROS, which were required to support ligand specific inflammatory and antiviral cytokine production. We also found that the magnitude of TLR3, but not TLR4, responses were modulated by glucose availability. Under conditions of low glucose, TLR3 engagement was associated with increased ETC complex III expression, increased mitochondrial and cytosolic ROS and increased inflammatory and antiviral cytokine production. This amplification was selectively reversed by targeting superoxide production from the outer Q-binding site of the ETC complex III. These results suggest that ligand specific modulation of the ETC may act as a rheostat that fine tunes innate immune responses via mitochondrial ROS production. Modulation of these processes may represent a novel mechanism to modulate the nature as well as the magnitude of antiviral vs. inflammatory immune responses.

Download Full-text

Differential remodeling of the electron transport chain is required to support TLR3 and TLR4 signaling and cytokine production in macrophages

10.1101/742098 ◽

2019 ◽

Author(s):

Duale Ahmed ◽

David Roy ◽

Allison Jaworski ◽

Alex Edwards ◽

Alfonso Abizaid ◽

...

Keyword(s):

Electron Transport ◽

Immune Responses ◽

Electron Transport Chain ◽

Cytokine Production ◽

Critical Role ◽

Innate Immune ◽

Fine Tuning ◽

Complex Iii ◽

Innate Immune Responses ◽

Transport Chain

AbstractIncreasing evidence suggests that mitochondria play a critical role in driving innate immune responses against bacteria and viruses. However, it is unclear if differential reprogramming of mitochondrial function contributes to the fine tuning of pathogen specific immune responses. Here, we found that TLR3 and TLR4 engagement on murine bone marrow derived macrophages was associated with differential remodeling of electron transport chain complex expression. This remodeling was associated with differential accumulation of mitochondrial and cytosolic ROS, which were required to support ligand specific inflammatory and antiviral cytokine production. We also found that the magnitude of TLR3, but not TLR4, responses were modulated by glucose availability. Under conditions of low glucose conditions, TLR3 engagement was associated with increased ETC complex III expression, increased mitochondrial and cytosolic ROS and increased inflammatory and antiviral cytokine production. This amplification was selectively reversed by targeting superoxide production from the outer Q-binding site of the ETC complex III. These results suggest that ligand specific modulation of the ETC may act as a rheostat that fine-tunes innate immune responses via mitochondrial ROS production. Modulation of these processes may represent a novel mechanism to modulate the nature as well as the magnitude of antiviral versus inflammatory immune responses.

Download Full-text

Hypoxia sensing in the fetal chicken femoral artery is mediated by the mitochondrial electron transport chain

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00500.2009 ◽

2010 ◽

Vol 298 (4) ◽

pp. R1026-R1034 ◽

Cited By ~ 14

Author(s):

Bea Zoer ◽

Angel L. Cogolludo ◽

Francisco Perez-Vizcaino ◽

Jo G. R. De Mey ◽

Carlos E. Blanco ◽

...

Keyword(s):

Polyethylene Glycol ◽

Electron Transport ◽

Electron Transport Chain ◽

Critical Role ◽

Complex Iii ◽

Mitochondrial Electron Transport Chain ◽

Voltage Gated ◽

Femoral Arteries ◽

Transport Chain ◽

Systemic Arteries

Vascular hypoxia sensing is transduced into vasoconstriction in the pulmonary circulation, whereas systemic arteries dilate. Mitochondrial electron transport chain (mETC), reactive O2 species (ROS), and K+ channels have been implicated in the sensing/signaling mechanisms of hypoxic relaxation in mammalian systemic arteries. We aimed to investigate their putative roles in hypoxia-induced relaxation in fetal chicken (19 days of incubation) femoral arteries mounted in a wire myograph. Acute hypoxia (Po2 ∼2.5 kPa) relaxed the contraction induced by norepinephrine (1 μM). Hypoxia-induced relaxation was abolished or significantly reduced by the mETC inhibitors rotenone (complex I), myxothiazol and antimycin A (complex III), and NaN3 (complex IV). The complex II inhibitor 3-nitroproprionic acid enhanced the hypoxic relaxation. In contrast, the relaxations mediated by acetylcholine, sodium nitroprusside, or forskolin were not affected by the mETC blockers. Hypoxia induced a slight increase in ROS production (as measured by 2,7-dichlorofluorescein-fluorescence), but hypoxia-induced relaxation was not affected by scavenging of superoxide (polyethylene glycol-superoxide dismutase) or H2O2 (polyethylene glycol-catalase) or by NADPH-oxidase inhibition (apocynin). Also, the K+ channel inhibitors tetraethylammonium (nonselective), diphenyl phosphine oxide-1 (voltage-gated K+ channel 1.5), glibenclamide (ATP-sensitive K+ channel), iberiotoxin (large-conductance Ca2+-activated K+ channel), and BaCl2 (inward-rectifying K+ channel), as well as ouabain (Na+-K+-ATPase inhibitor) did not affect hypoxia-induced relaxation. The relaxation was enhanced in the presence of the voltage-gated K+ channel blocker 4-aminopyridine. In conclusion, our experiments suggest that the mETC plays a critical role in O2 sensing in fetal chicken femoral arteries. In contrast, hypoxia-induced relaxation appears not to be mediated by ROS or K+ channels.

Download Full-text

AB0031 T HELPER 17 CELLS WERE SIGNIFICANTLY DECREASED BY MITOCHONDRIAL ELECTRON TRANSPORT CHAIN COMPLEX INHIBITOR IN PATIENTS WITH RHEUMATOID ARTHRITIS

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2020-eular.3441 ◽

2020 ◽

Vol 79 (Suppl 1) ◽

pp. 1318.2-1318

Author(s):

H. R. Lee ◽

S. J. Yoo ◽

J. Kim ◽

I. S. Yoo ◽

C. K. Park ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

Electron Transport ◽

Disease Activity ◽

Th17 Cells ◽

Electron Transport Chain ◽

Chain Complex ◽

Complex Iii ◽

Mitochondrial Electron Transport Chain ◽

Transport Chain ◽

Healthy Control

Background:Reactive oxygen species (ROS) and T helper 17 (TH17) cells have been known to play an important role in the pathogenesis of rheumatoid arthritis (RA). However, the interrelationship between ROS and TH17 remains unclear in RAObjectives:To explore whether ROS affect TH17 cells in peripheral blood mononuclear cells (PBMC) of RA patients, we analyzed ROS expressions among T cell subsets following treatment with mitochondrial electron transport chain complex inhibitors.Methods:Blood samples were collected from 40 RA patients and 10 healthy adult volunteers. RA activity was divided according to clinical parameter DAS28. PBMC cells were obtained from the whole blood using lymphocyte separation medium density gradient centrifugation. Following PBMC was stained with Live/Dead stain dye, cells were incubated with antibodies for CD3, CD4, CD8, and CD25. After fixation and permeabilization, samples were stained with antibodies for FoxP3 and IL-17A. MitoSox were used for mitochondrial specific staining.Results:The frequency of TH17 cells was increased by 4.83 folds in moderate disease activity group (5.1>DAS28≥3.2) of RA patients compared to healthy control. Moderate RA activity patients also showed higher ratio of TH17/Treg than healthy control (3.57 folds). All RA patients had elevated expression of mitochondrial specific ROS than healthy control. When PBMC cells were treated with 2.5uM of antimycin A (mitochondrial electron transport chain complex III inhibitor) for 16 h, the frequency of TH17 cells was significantly decreased.Conclusion:The mitochondrial electron transport chain complex III inhibitor markedly downregulated the frequency of TH17 cells in moderate disease activity patients with RA. These findings provide a novel approach to regulate TH17 function in RA through mitochondrial metabolism related ROS production.References:[1]Szekanecz, Z., et al., New insights in synovial angiogenesis. Joint Bone Spine, 2010. 77(1): p. 13-9.[2]Prevoo, M.L., et al., Modified disease activity scores that include twenty-eight-joint counts. Development and validation in a prospective longitudinal study of patients with rheumatoid arthritis. Arthritis Rheum, 1995. 38(1): p. 44-8.Disclosure of Interests:None declared

Download Full-text

Critical Role of Plasmacytoid Dendritic Cells in Regulating Gene Expression and Innate Immune Responses to Human Rhinovirus-16

Frontiers in Immunology ◽

10.3389/fimmu.2017.01351 ◽

2017 ◽

Vol 8 ◽

Cited By ~ 6

Author(s):

Yang Xi ◽

Niamh M. Troy ◽

Denise Anderson ◽

Olga M. Pena ◽

Jason P. Lynch ◽

...

Keyword(s):

Gene Expression ◽

Dendritic Cells ◽

Immune Responses ◽

Critical Role ◽

Plasmacytoid Dendritic Cells ◽

Innate Immune ◽

Human Rhinovirus ◽

Innate Immune Responses

Download Full-text

The microbiota plays a critical role in the reactivity of lung immune components to innate ligands

10.1101/2020.10.19.345116 ◽

2020 ◽

Author(s):

Quentin Marquant ◽

Daphné Laubreton ◽

Carole Drajac ◽

Elliot Mathieu ◽

Edwige Bouguyon ◽

...

Keyword(s):

Immune Responses ◽

Critical Role ◽

Innate Immune ◽

Immune Reactivity ◽

Innate Immune Responses ◽

Plain Language ◽

Pulmonary Tissue ◽

Germ Free ◽

Syncytial Virus

AbstractThe microbiota contributes to shaping efficient and safe immune defenses in the gut. However, little is known about the role of the microbiota in the education of pulmonary innate immune responses. Here, we tested whether the endogenous microbiota can modulate reactivity of pulmonary tissue to pathogen stimuli by comparing the response of specific pathogen-free (SPF) and germ-free (GF) mice. Using SPF and GF mice intranasally exposed to lipopolysaccharide (LPS), a component of Gram-negative bacteria, we observed earlier and greater inflammation in the pulmonary compartment of GF mice than that of SPF mice. Toll-like receptor 4 (TLR4) was more abundantly expressed in the lungs of GF mice than those of SPF mice at steady state, which could predispose the innate immunity of GF mice to strongly react to environmental stimuli. Lung explants were stimulated with different TLR agonists or infected with the human airways pathogen, respiratory syncytial virus (RSV), resulting in greater inflammation under almost all conditions for the GF explants. Finally, alveolar macrophages (AM) from GF mice presented a higher innate immune response upon RSV infection than those of SPF mice. Overall, these data suggest that the presence of microbiota in SPF mice induced a process of innate immune tolerance in the lungs by a mechanism which remains to be elucidated. Our study represents a step forward to establishing the link between the microbiota and the immune reactivity of the lungs.Plain Language summaryMicrobiota represents an important partner of immunologic system at the interface between immune cells and epithelium. It is well known, notably in the gut, that the microbiota contributes in shaping efficient and safe defenses. However, little is known about the role of the microbiota in the education of pulmonary innate immune responses. In this study, we postulate that endogenous microbiota could dampen an excessive reactivity of pulmonary tissue to external stimuli. Thus, we sought to study the innate immune reaction switched on by viral or bacterial ligands in respiratory tract cells coming from mice with or without microbiota (germ-free condition, GF). Altogether, our results show a higher inflammatory reaction in GF condition. This study represents a step forward to better establish the link between the microbiota and the reactivity of the lung tissue. Not only these data demonstrate that the microbiota educates the pulmonary innate immune system, but also contributes the emerging concept of using respiratory commensal bacteria as potential next-generation probiotics to prevent susceptibility to respiratory diseases.

Download Full-text

Mycobacterium tuberculosisinhibits human innate immune responses via the production of TLR2 antagonist glycolipids

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1707840114 ◽

2017 ◽

Vol 114 (42) ◽

pp. 11205-11210 ◽

Cited By ~ 33

Author(s):

Landry Blanc ◽

Martine Gilleron ◽

Jacques Prandi ◽

Ok-ryul Song ◽

Mi-Seon Jang ◽

...

Keyword(s):

Immune Responses ◽

Molecular Mechanisms ◽

Cytokine Production ◽

Cell Envelope ◽

Costimulatory Molecule ◽

Immune Defense ◽

Innate Immune ◽

Host Cells ◽

Innate Immune Responses ◽

Reporter System

Mycobacterium tuberculosisis a major human pathogen that is able to survive inside host cells and resist immune clearance. Most particularly, it inhibits several arms of the innate immune response, including phagosome maturation or cytokine production. To better understand the molecular mechanisms by whichM. tuberculosiscircumvents host immune defenses, we used a transposon mutant library generated in a virulent clinical isolate ofM. tuberculosisof the W/Beijing family to infect human macrophages, utilizing a cell line derivative of THP-1 cells expressing a reporter system for activation of the transcription factor NF-κB, a key regulator of innate immunity. We identified severalM. tuberculosismutants inducing a NF-κB activation stronger than that of the wild-type strain. One of these mutants was found to be deficient for the synthesis of cell envelope glycolipids, namely sulfoglycolipids, suggesting that the latter can interfere with innate immune responses. Using natural and synthetic molecular variants, we determined that sulfoglycolipids inhibit NF-κB activation and subsequent cytokine production or costimulatory molecule expression by acting as competitive antagonists of Toll-like receptor 2, thereby inhibiting the recognition ofM. tuberculosisby this receptor. Our study reveals that producing glycolipid antagonists of pattern recognition receptors is a strategy used byM. tuberculosisto undermine innate immune defense. Sulfoglycolipids are major and specific lipids ofM. tuberculosis, considered for decades as virulence factors of the bacilli. Our study uncovers a mechanism by which they may contribute toM. tuberculosisvirulence.

Download Full-text

Evolutionary and structural analysis of SARS-CoV-2 specific evasion of host immunity

Genes and Immunity ◽

10.1038/s41435-020-00120-6 ◽

2020 ◽

Vol 21 (6-8) ◽

pp. 409-419

Author(s):

Irfan Hussain ◽

Nashaiman Pervaiz ◽

Abbas Khan ◽

Shoaib Saleem ◽

Huma Shireen ◽

...

Keyword(s):

Immune Responses ◽

Nonstructural Protein ◽

Critical Role ◽

Clinical Manifestations ◽

Host Immunity ◽

Innate Immune ◽

Host Immune System ◽

Innate Immune Responses ◽

In Vivo Models

AbstractThe outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading fast worldwide. There is a pressing need to understand how the virus counteracts host innate immune responses. Deleterious clinical manifestations of coronaviruses have been associated with virus-induced direct dysregulation of innate immune responses occurring via viral macrodomains located within nonstructural protein-3 (Nsp3). However, no substantial information is available concerning the relationship of macrodomains to the unusually high pathogenicity of SARS-CoV-2. Here, we show that structural evolution of macrodomains may impart a critical role to the unique pathogenicity of SARS-CoV-2. Using sequence, structural, and phylogenetic analysis, we identify a specific set of historical substitutions that recapitulate the evolution of the macrodomains that counteract host immune response. These evolutionary substitutions may alter and reposition the secondary structural elements to create new intra-protein contacts and, thereby, may enhance the ability of SARS-CoV-2 to inhibit host immunity. Further, we find that the unusual virulence of this virus is potentially the consequence of Darwinian selection‐driven epistasis in protein evolution. Our findings warrant further characterization of macrodomain-specific evolutionary substitutions in in vitro and in vivo models to determine their inhibitory effects on the host immune system.

Download Full-text

A Chemogenomic Screen in Saccharomyces cerevisiae Uncovers a Primary Role for the Mitochondria in Farnesol Toxicity and Its Regulation by the Pkc1 Pathway

Journal of Biological Chemistry ◽

10.1074/jbc.m610575200 ◽

2006 ◽

Vol 282 (7) ◽

pp. 4868-4874 ◽

Cited By ~ 44

Author(s):

Gregory D. Fairn ◽

Kendra MacDonald ◽

Christopher R. McMaster

Keyword(s):

Saccharomyces Cerevisiae ◽

Reactive Oxygen Species ◽

Cell Death ◽

Electron Transport ◽

Signaling Pathway ◽

Electron Transport Chain ◽

Reactive Oxygen ◽

Complex Iii ◽

Oxygen Species ◽

Transport Chain

The isoprenoid farnesol has been shown to preferentially induce apoptosis in cancerous cells; however, the mode of action of farnesol-induced death is not established. We used chemogenomic profiling using Saccharomyces cerevisiae to probe the core cellular processes targeted by farnesol. This screen revealed 48 genes whose inactivation increased sensitivity to farnesol. The gene set indicated a role for the generation of oxygen radicals by the Rieske iron-sulfur component of complex III of the electron transport chain as a major mediator of farnesol-induced cell death. Consistent with this, loss of mitochondrial DNA, which abolishes electron transport, resulted in robust resistance to farnesol. A genomic interaction map predicted interconnectedness between the Pkc1 signaling pathway and farnesol sensitivity via regulation of the generation of reactive oxygen species. Consistent with this prediction (i) Pkc1, Bck1, and Mkk1 relocalized to the mitochondria upon farnesol addition, (ii) inactivation of the only non-essential and non-redundant member of the Pkc1 signaling pathway, BCK1, resulted in farnesol sensitivity, and (iii) expression of activated alleles of PKC1, BCK1, and MKK1 increased resistance to farnesol and hydrogen peroxide. Sensitivity to farnesol was not affected by the presence of the osmostabilizer sorbitol nor did farnesol affect phosphorylation of the ultimate Pkc1-responsive kinase responsible for controlling the cell wall integrity pathway, Slt2. The data indicate that the generation of reactive oxygen species by the electron transport chain is a primary mechanism by which farnesol kills cells. The Pkc1 signaling pathway regulates farnesol-mediated cell death through management of the generation of reactive oxygen species.

Download Full-text