scholarly journals The Translocator Protein (TSPO) in Mitochondrial Bioenergetics and Immune Processes

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 512 ◽  
Author(s):  
Calina Betlazar ◽  
Ryan J. Middleton ◽  
Richard Banati ◽  
Guo-Jun Liu
Keyword(s):  
Paradigm Shift ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
Translocator Protein ◽  
Imaging Studies ◽  
Immunomodulatory Effects ◽  
Cellular Functions ◽  
Mitochondrial Functions ◽  
Cellular Bioenergetics ◽  
Mitochondrial Membrane Protein

The translocator protein (TSPO) is an outer mitochondrial membrane protein that is widely used as a biomarker of neuroinflammation, being markedly upregulated in activated microglia in a range of brain pathologies. Despite its extensive use as a target in molecular imaging studies, the exact cellular functions of this protein remain in question. The long-held view that TSPO plays a fundamental role in the translocation of cholesterol through the mitochondrial membranes, and thus, steroidogenesis, has been disputed by several groups with the advent of TSPO knockout mouse models. Instead, much evidence is emerging that TSPO plays a fundamental role in cellular bioenergetics and associated mitochondrial functions, also part of a greater role in the innate immune processes of microglia. In this review, we examine the more direct experimental literature surrounding the immunomodulatory effects of TSPO. We also review studies which highlight a more central role for TSPO in mitochondrial processes, from energy metabolism, to the propagation of inflammatory responses through reactive oxygen species (ROS) modulation. In this way, we highlight a paradigm shift in approaches to TSPO functioning.

scholarly journals Terminal uridyltransferase 7 regulates TLR4-triggered inflammation by controlling Regnase-1 mRNA uridylation and degradation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chia-Ching Lin ◽  
Yi-Ru Shen ◽  
Chi-Chih Chang ◽  
Xiang-Yi Guo ◽  
Yun-Yun Young ◽  
...  
Keyword(s):  
Posttranscriptional Regulation ◽  
Inflammatory Responses ◽  
Rna Stability ◽  
Innate Immune ◽  
Stem Loop ◽  
Stem Loop Structure ◽  
Tlr4 Activation ◽  
Harmful Effects ◽  
Different Levels

AbstractDifferent levels of regulatory mechanisms, including posttranscriptional regulation, are needed to elaborately regulate inflammatory responses to prevent harmful effects. Terminal uridyltransferase 7 (TUT7) controls RNA stability by adding uridines to its 3′ ends, but its function in innate immune response remains obscure. Here we reveal that TLR4 activation induces TUT7, which in turn selectively regulates the production of a subset of cytokines, including Interleukin 6 (IL-6). TUT7 regulates IL-6 expression by controlling ribonuclease Regnase-1 mRNA (encoded by Zc3h12a gene) stability. Mechanistically, TLR4 activation causes TUT7 to bind directly to the stem-loop structure on Zc3h12a 3′-UTR, thereby promotes Zc3h12a uridylation and degradation. Zc3h12a from LPS-treated TUT7-sufficient macrophages possesses increased oligo-uridylated ends with shorter poly(A) tails, whereas oligo-uridylated Zc3h12a is significantly reduced in Tut7-/- cells after TLR4 activation. Together, our findings reveal the functional role of TUT7 in sculpting TLR4-driven responses by modulating mRNA stability of a selected set of inflammatory mediators.

scholarly journals MyD88-Dependent Signaling Affects the Development of Meningococcal Sepsis by Nonlipooligosaccharide Ligands

2006 ◽  
Vol 74 (6) ◽  
pp. 3538-3546 ◽  
Author(s):  
Laura Plant ◽  
Hong Wan ◽  
Ann-Beth Jonsson
Keyword(s):  
Inflammatory Responses ◽  
Innate Immune ◽  
Meningococcal Sepsis ◽  
Wild Type ◽  
Microbial Infections ◽  
In The Wild ◽  
Myeloid Differentiation Factor ◽  
Dependent Pathway ◽  
Meningococcal Strain

ABSTRACT The Toll-like receptors (TLRs) and the adaptor myeloid differentiation factor 88 (MyD88) are important in the innate immune defenses of the host to microbial infections. Meningococcal ligands signaling via TLRs control inflammatory responses, and stimulation can result in fulminant meningococcal sepsis. In this study, we show that the responses to nonlipooligosaccharide (non-LOS) ligands of meningococci are MyD88 dependent. An isogenic LOS-deficient mutant of the serogroup C meningococcal strain FAM20 caused fatal disease in wild type C57BL/6 mice that was not observed in MyD88−/− mice. Fatality correlated with high proinflammatory cytokine and C5a levels in serum, high neutrophil numbers in blood, and increased bacteremia at 24 h postinfection in the wild-type mice. Infection with the parent strain FAM20 resulted in fatality in 100% of the wild-type mice and 50% of the MyD88−/− mice. We conclude that both LOS and another neisserial ligand cause meningococcal sepsis in an in vivo mouse model and confirm that meningococcal LOS can act via both the MyD88- dependent and -independent pathways, while the non-LOS meningococcal ligand(s) acts only via the MyD88-dependent pathway.

scholarly journals Activated Platelets Induce an Anti-Inflammatory Response of Monocytes/Macrophages through Cross-Regulation of PGE2and Cytokines

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Bona Linke ◽  
Yannick Schreiber ◽  
Bettina Picard-Willems ◽  
Patrick Slattery ◽  
Rolf M. Nüsing ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Cell Types ◽  
Inhibitory Effect ◽  
Innate Immune ◽  
Prostaglandin E ◽  
Murine Bone Marrow ◽  
Activated Platelets ◽  
Monocytes And Macrophages ◽  
Inflammatory Processes ◽  
Necrosis Factor

Platelets are well known for their role in hemostasis and are also increasingly recognized for their roles in the innate immune system during inflammation and their regulation of macrophage activation. Here, we aimed to study the influence of platelets on the production of inflammatory mediators by monocytes and macrophages. Analyzing cocultures of platelets and murine bone marrow-derived macrophages or human monocytes, we found that collagen-activated platelets release high amounts of prostaglandin E2(PGE2) that leads to an increased interleukin- (IL-) 10 release and a decreased tumor necrosis factor (TNF)αsecretion out of the monocytes or macrophages. Platelet PGE2mediated the upregulation of IL-10 in both cell types via the PGE2receptor EP2. Notably, PGE2-mediated IL-10 synthesis was also mediated by EP4 in murine macrophages. Inhibition of TNFαsynthesis via EP2 and EP4, but not EP1, was mediated by IL-10, since blockade of the IL-10 receptor abolished the inhibitory effect of both receptors on TNFαrelease. This platelet-mediated cross-regulation between PGE2and cytokines reveals one mechanism how monocytes and macrophages can attenuate excessive inflammatory responses induced by activated platelets in order to limit inflammatory processes.

scholarly journals microRNA-210 and microRNA-3570 Negatively Regulate NF-κB-Mediated Inflammatory Responses by Targeting RIPK2 in Teleost Fish

2021 ◽  
Vol 12 ◽  
Author(s):  
Hui Su ◽  
Renjie Chang ◽  
Weiwei Zheng ◽  
Yuena Sun ◽  
Tianjun Xu
Keyword(s):  
Immune Response ◽  
Signaling Pathway ◽  
Innate Immune Response ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
Regulatory Role ◽  
Inflammatory Cytokine Production ◽  
Immune Genes ◽  
Lower Vertebrates ◽  
Antimicrobial Immunity

Pathogen infection can cause the production of inflammatory cytokines, which are key mediators that cause the host’s innate immune response. Therefore, proper regulation of immune genes associated with inflammation is essential for immune response. Among them, microRNAs (miRNAs) as gene regulator have been widely reported to be involved in the innate immune response of mammals. However, the regulatory network in which miRNAs are involved in the development of inflammation is largely unknown in lower vertebrates. Here, we identified two miRNAs from miiuy croaker (Miichthys miiuy), miR-210 and miR-3570, which play a negative regulatory role in host antibacterial immunity. We found that the expressions of miR-210 and miR-3570 were significantly upregulated under the stimulation of Gram-negative bacterium vibrio harveyi and LPS (lipopolysaccharide). Induced miR-210 and miR-3570 inhibit inflammatory cytokine production by targeting RIPK2, thereby avoiding excessive inflammation. In particular, we found that miR-210 and miR-3570 negatively regulate antimicrobial immunity by regulating the RIPK2-mediated NF-κB signaling pathway. The collective results indicated that both miRNAs are used as negative feedback regulators to regulate RIPK2-mediated NF-κB signaling pathway and thus play a regulatory role in bacteria-induced inflammatory response.

scholarly journals Mitochondrial DNA as an inflammatory mediator in cardiovascular diseases

2018 ◽  
Vol 475 (5) ◽  
pp. 839-852 ◽  
Author(s):  
Hiroyuki Nakayama ◽  
Kinya Otsu
Keyword(s):  
Mitochondrial Dna ◽  
Inflammatory Responses ◽  
Inflammatory Cells ◽  
Nuclear Factor Κb ◽  
Sterile Inflammation ◽  
Microbial Infection ◽  
Cellular Functions ◽  
Radical Oxygen Species ◽  
Cardiac Inflammation ◽  
Contraction And Relaxation

Mitochondria play a central role in multiple cellular functions, including energy production, calcium homeostasis, and cell death. Currently, growing evidence indicates the vital roles of mitochondria in triggering and maintaining inflammation. Chronic inflammation without microbial infection — termed sterile inflammation — is strongly involved in the development of heart failure. Sterile inflammation is triggered by the activation of pattern recognition receptors (PRRs) that sense endogenous ligands called damage-associated molecular patterns (DAMPs). Mitochondria release multiple DAMPs including mitochondrial DNA, peptides, and lipids, which induce inflammation via the stimulation of multiple PRRs. Among the mitochondrial DAMPs, mitochondrial DNA (mtDNA) is currently highlighted as the DAMP that mediates the activation of multiple PRRs, including Toll-like receptor 9, Nod-like receptors, and cyclic GMP–AMP synthetase/stimulator of interferon gene pathways. These PRR signalling pathways, in turn, lead to the activation of nuclear factor-κB and interferon regulatory factor, which enhances the transcriptional activity of inflammatory cytokines and interferons, and induces the recruitment of inflammatory cells. As the heart is an organ comprising abundant mitochondria for its ATP consumption (needed to maintain constant cyclic contraction and relaxation), the generation of massive amounts of mitochondrial radical oxygen species and mitochondrial DAMPs are predicted to occur and promote cardiac inflammation. Here, we will focus on the role of mtDNA in cardiac inflammation and review the mechanism and pathological significance of mtDNA-induced inflammatory responses in cardiac diseases.

scholarly journals Effects of elevated CO2 levels on lung immune response to organic dust and lipopolysaccaride

2021 ◽  
Author(s):  
David Schneberger ◽  
Upkardeep Singh Pandher ◽  
Brooke Thompson ◽  
Shelley Kirychuk
Keyword(s):  
Immune Responses ◽  
Inflammatory Responses ◽  
Animal Feed ◽  
Weighted Average ◽  
Innate Immune ◽  
Mrna Levels ◽  
Innate Immune Responses ◽  
Organic Dust ◽  
Complex Environments ◽  
Time Weighted Average

Abstract Workplaces with elevated organic dust levels such as animal feed barns also commonly have elevated levels of gasses, such as CO2. Workers exposed to such complex environments often experience respiratory effects that may be due to a combination of respirable factors. We examined the effects of CO2 at the ASHRAE recommended limit (1000 ppm) as well as the EPA 8hr time weighted average limit (5000 ppm) on lung innate immune responses in mice with exposure to inflammatory lipopolysaccharide and organic dust. Mice were nasally instilled with dust extracts or LPS and immediately put into chambers with a constant flow of room air (approx. 430 ppm CO2), 1000 ppm, or 5000 ppm CO2 enriched air. Organic dust exposures tended to show decreased inflammatory responses with 1000 ppm CO2 and increased responses at 5000 ppm CO2. Conversely, LPS with addition of CO2 as low as 1000 ppm tended to inhibit several inflammatory markers. In most cases saline treated animals showed few changes with CO2 exposure, though some changes in mRNA levels were present. This shows that CO2 as low as 1000 ppm CO2 was capable of altering innate immune responses to both LPS and organic dust extracts, but each response was altered in a different fashion.

scholarly journals Prevailing role of mucosal immunoglobulins and B cells in teleost skin immune responses to bacterial infection

2020 ◽  
Author(s):  
Xiao-Ting Zhang ◽  
Yong-Yao Yu ◽  
Hao-Yue Xu ◽  
Zhen-Yu Huang ◽  
Xia Liu ◽  
...  
Keyword(s):  
B Cells ◽  
Bacterial Infection ◽  
Inflammatory Responses ◽  
The Body ◽  
Innate Immune ◽  
Flavobacterium Columnare ◽  
First Line ◽  
Skin Mucus ◽  
Skin Mucosa

AbstractThe skin of vertebrates is the outermost organ of the body and serves as the first line of defense against external aggressions. In contrast to mammalian skin, that of teleost fish lacks keratinization and has evolved to operate as a mucosal surface containing a skin-associated lymphoid tissue (SALT). Thus far, IgT representing the prevalent immunoglobulin (Ig) in SALT have only been reported upon infection with a parasite. However, very little is known about the types of B cells and Igs responding to bacterial infection in the teleost skin mucosa, as well as the inductive or effector role of the SALT in such responses. To address these questions, here we analyzed the immune response of trout skin upon infection with one of the most widespread fish skin bacterial pathogens, Flavobacterium columnare. This pathogen induced strong skin innate immune and inflammatory responses at the initial phases of infection. More critically, we found that the skin mucus of fish having survived the infection contained significant IgT-but not IgM- or IgD-specific titers against the bacteria. Moreover, we demonstrate the local proliferation and production of IgT+ B-cells and specific IgT titers respectively within the SALT upon bacterial infection. Thus, our findings represent the first demonstration that IgT is the main Ig isotype induced by the skin mucosa upon bacterial infection, and that because of the large surface of the skin, its SALT probably represents a prominent IgT inductive site in fish.

scholarly journals Inflammatory Responses during Tumour Initiation: From Zebrafish Transgenic Models of Cancer to Evidence from Mouse and Man

2020 ◽  
Author(s):  
Abigail Elliot ◽  
Henna Myllymäki ◽  
Yi Feng
Keyword(s):  
Immune Cells ◽  
Cancer Biology ◽  
Inflammatory Responses ◽  
Live Imaging ◽  
Innate Immune ◽  
Leukocyte Recruitment ◽  
Innate Immune Cells ◽  
Neoplastic Cells ◽  
Tumour Development ◽  
Tumour Initiation

The zebrafish is now an important model organism for cancer biology studies and provides some unique and complementary opportunities in comparison to the mammalian equivalent. The translucency of zebrafish has allowed in vivo live imaging studies of tumour initiation and progression at the cellular level thus providing novel insights into our understanding of cancer. Here we summarise and discuss available transgenic zebrafish tumour models and what we have gleaned from them with respect to cancer inflammation. In particular, we focus on the host inflammatory response toward transformed cells during the pre-neoplastic stage of tumour development. We discuss features of tumour associated macrophages and neutrophils in mammalian models and present evidence which supports the idea that these inflammatory cells promote early stage tumour development and progression. Direct live imaging of tumour initiation in zebrafish models has shown that the intrinsic inflammation induced by pre-neoplastic cells is tumour promoting. Signals mediating leukocyte recruitment to pre-neoplastic cells in zebrafish correspond to signals mediating leukocyte recruitment in mammalian tumours. The activation state of macrophages and neutrophils recruited to pre-neoplastic cells appears to be heterogenous, as seen in mammalian models, which provides an opportunity to study the plasticity of innate immune cells during tumour initiation. Although several potential mechanisms are described that might mediate the trophic function of innate immune cells during tumour initiation in zebrafish, there are several unknowns that are yet to be resolved. Rapid advancement of genetic tools and imaging technologies for zebrafish will facilitate research into the mechanisms that modulate leukocyte function during tumour initiation and identify targets for cancer prevention.

scholarly journals The role of TLR-4 in the immunomodulatory effects of recombinant BCG expressing MSP-1C of Plasmodium falciparum

2019 ◽  
Vol 13 (11) ◽  
pp. 1057-1061
Author(s):  
Muhammad Adamu Abbas ◽  
Rapeah Suppian
Keyword(s):  
Nitric Oxide ◽  
Plasmodium Falciparum ◽  
Inflammatory Responses ◽  
Peritoneal Macrophages ◽  
Significant Inhibition ◽  
Immunomodulatory Effects ◽  
Attachment Mechanism ◽  
Significant Production ◽  
Recombinant Bcg

Introduction: An earlier constructed recombinant BCG expressing the MSP-1C of Plasmodium falciparum, induced inflammatory responses leading to significant production of nitric oxide (NO) alongside higher expression of the enzyme inducible nitric oxide synthase (iNOS) and significant production of the regulatory cytokine, IL-10, indicating significant immunomodulatory effects of the construct. The mechanism of these responses had not been established but is thought to involve toll-like receptor 4 (TLR-4). Methodology: The present study was carried out to determine the role of TLR-4 on eliciting the immunomodulatory effects of recombinant BCG expressing MSP-1C of Plasmodium falciparum leading to the production of NO and IL-10, as well as the expression of iNOS. Six groups of mice (n = 6 per group) were immunised thrice, three weeks apart with intraperitoneal phosphate buffered saline T80 (PBS-T80), BCG or rBCG in the presence or absence of a TLR-4 inhibitor; TAK-242, given one hour prior to each immunisation. Peritoneal macrophages were harvested from the mice and cultured for the determination of NO, iNOS and IL-10 via Griess assay, ELISA and Western blot respectively. Results: The results showed significant inhibition of the production of NO and IL-10 and the expression of iNOS in all groups of mice in the presence of TAK-242. Conclusions: These results presented evidence of the role of TLR-4/rBCG attachment mechanism in modulating the production of NO and IL-10 and the expression of iNOS in response to our rBCG-based malaria vaccine candidate expressing MSP-1C of P. falciparum.

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