scholarly journals Channels and Transporters of the Pulmonary Lamellar Body in Health and Disease

Cells ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 45
Author(s):  
Paul Dietl ◽  
Manfred Frick
Keyword(s):  
Viral Infections ◽  
Lamellar Body ◽  
Innate Immune ◽  
Alveolar Type ◽  
Ion Composition ◽  
Danger Signal ◽  
Major Function ◽  
Health And Disease ◽  
P2x4 Receptors ◽  
Organelle Membrane

The lamellar body (LB) of the alveolar type II (ATII) cell is a lysosome-related organelle (LRO) that contains surfactant, a complex mix of mainly lipids and specific surfactant proteins. The major function of surfactant in the lung is the reduction of surface tension and stabilization of alveoli during respiration. Its lack or deficiency may cause various forms of respiratory distress syndrome (RDS). Surfactant is also part of the innate immune system in the lung, defending the organism against air-borne pathogens. The limiting (organelle) membrane that encloses the LB contains various transporters that are in part responsible for translocating lipids and other organic material into the LB. On the other hand, this membrane contains ion transporters and channels that maintain a specific internal ion composition including the acidic pH of about 5. Furthermore, P2X4 receptors, ligand gated ion channels of the danger signal ATP, are expressed in the limiting LB membrane. They play a role in boosting surfactant secretion and fluid clearance. In this review, we discuss the functions of these transporting pathways of the LB, including possible roles in disease and as therapeutic targets, including viral infections such as SARS-CoV-2.

scholarly journals Nrf2 Lowers the Risk of Lung Injury via Modulating the Airway Innate Immune Response Induced by Diesel Exhaust in Mice

Biomedicines ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 443
Author(s):  
Ying-Ji Li ◽  
Takako Shimizu ◽  
Yusuke Shinkai ◽  
Tomomi Ihara ◽  
Masao Sugamata ◽  
...  
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Lung Tissue ◽  
Diesel Exhaust ◽  
Cell Injury ◽  
Lamellar Body ◽  
Lavage Fluid ◽  
Innate Immune ◽  
Alveolar Type ◽  
Tnf Α

In the present study, we investigated the role of Nrf2 in airway immune responses induced by diesel exhaust (DE) inhalation in mice. C57BL/6J Nrf2+/+ and Nrf2−/− mice were exposed to DE or clean air for 8 h/day and 6 days/week for 4 weeks. After DE exposure, the number of neutrophils and macrophage inflammatory protein (MIP)-2 level in bronchoalveolar lavage fluid (BALF) and interleukin (IL)-17 level in the lung tissue increased in Nrf2−/− mice compared with Nrf2+/+ mice; however, the lack of an increase in the level of tumor necrosis factor (TNF)-α in the lung tissue in Nrf2+/+ mice and mild suppression of the level of TNF-α in Nrf2−/− mice were observed; the level of granulocyte macrophage colony-stimulating factor (GM-CSF) in the lung tissue decreased in Nrf2−/− mice than in Nrf2+/+ mice; the number of DE particle-laden alveolar macrophages in BALF were larger in Nrf2−/− mice than in Nrf2+/+ mice. The results of electron microscope observations showed alveolar type II cell injury and degeneration of the lamellar body after DE exposure in Nrf2−/− mice. Antioxidant enzyme NAD(P)H quinone dehydrogenase (NQO)1 mRNA expression level was higher in Nrf2+/+ mice than in Nrf2−/− mice after DE exposure. Our results suggested that Nrf2 reduces the risk of pulmonary disease via modulating the airway innate immune response caused by DE in mice.

scholarly journals The Role of Cell Metabolism in Innate Immune Memory

2020 ◽  
pp. 1-9
Author(s):  
Anaisa Valido Ferreira ◽  
Jorge Domiguéz-Andrés ◽  
Mihai Gheorghe Netea
Keyword(s):  
Metabolic Pathways ◽  
Tricarboxylic Acid Cycle ◽  
Cell Metabolism ◽  
Innate Immune ◽  
Immune Memory ◽  
Functional Changes ◽  
Trained Immunity ◽  
Health And Disease

Immunological memory is classically attributed to adaptive immune responses, but recent studies have shown that challenged innate immune cells can display long-term functional changes that increase nonspecific responsiveness to subsequent infections. This phenomenon, coined <i>trained immunity</i> or <i>innate immune memory</i>, is based on the epigenetic reprogramming and the rewiring of intracellular metabolic pathways. Here, we review the different metabolic pathways that are modulated in trained immunity. Glycolysis, oxidative phosphorylation, the tricarboxylic acid cycle, amino acid, and lipid metabolism are interplaying pathways that are crucial for the establishment of innate immune memory. Unraveling this metabolic wiring allows for a better understanding of innate immune contribution to health and disease. These insights may open avenues for the development of future therapies that aim to harness or dampen the power of the innate immune response.

scholarly journals The L1-dependant and Pol III transcribed Alu retrotransposon, from its discovery to innate immunity

2021 ◽  
Vol 48 (3) ◽  
pp. 2775-2789
Author(s):  
Ludwig Stenz
Keyword(s):  
Human Genome ◽  
Viral Infections ◽  
De Novo ◽  
Current Knowledge ◽  
Innate Immune ◽  
De Novo Mutation ◽  
Neuronal Diversity ◽  
Alu Sequences ◽  
Pol Iii ◽  
The Brain

AbstractThe 300 bp dimeric repeats digestible by AluI were discovered in 1979. Since then, Alu were involved in the most fundamental epigenetic mechanisms, namely reprogramming, pluripotency, imprinting and mosaicism. These Alu encode a family of retrotransposons transcribed by the RNA Pol III machinery, notably when the cytosines that constitute their sequences are de-methylated. Then, Alu hijack the functions of ORF2 encoded by another transposons named L1 during reverse transcription and integration into new sites. That mechanism functions as a complex genetic parasite able to copy-paste Alu sequences. Doing that, Alu have modified even the size of the human genome, as well as of other primate genomes, during 65 million years of co-evolution. Actually, one germline retro-transposition still occurs each 20 births. Thus, Alu continue to modify our human genome nowadays and were implicated in de novo mutation causing diseases including deletions, duplications and rearrangements. Most recently, retrotransposons were found to trigger neuronal diversity by inducing mosaicism in the brain. Finally, boosted during viral infections, Alu clearly interact with the innate immune system. The purpose of that review is to give a condensed overview of all these major findings that concern the fascinating physiology of Alu from their discovery up to the current knowledge.

Tracing surfactant transformation from cellular release to insertion into an air-liquid interface

2004 ◽  
Vol 286 (5) ◽  
pp. L1009-L1015 ◽  
Author(s):  
T. Haller ◽  
P. Dietl ◽  
H. Stockner ◽  
M. Frick ◽  
N. Mair ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cultured Cells ◽  
High Surface ◽  
Lamellar Body ◽  
Liquid Interface ◽  
Alveolar Type ◽  
Tensile Forces ◽  
Modify Surface ◽  
Fluorescence Imaging Microscopy ◽  
Air Liquid Interface

Pulmonary surfactant is secreted by alveolar type II cells as lipid-rich, densely packed lamellar body-like particles (LBPs). The particulate nature of released LBPs might be the result of structural and/or thermodynamic forces. Thus mechanisms must exist that promote their transformation into functional units. To further define these mechanisms, we developed methods to follow LBPs from their release by cultured cells to insertion in an air-liquid interface. When released, LBPs underwent structural transformation, but did not disperse, and typically preserved a spherical appearance for days. Nevertheless, they were able to modify surface tension and exhibited high surface activity when measured with a capillary surfactometer. When LBPs inserted in an air-liquid interface were analyzed by fluorescence imaging microscopy, they showed remarkable structural transformations. These events were instantaneous but came to a halt when the interface was already occupied by previously transformed material or when surface tension was already low. These results suggest that the driving force for LBP transformation is determined by cohesive and tensile forces acting on these particles. They further suggest that transformation of LBPs is a self-regulated interfacial process that most likely does not require structural intermediates or enzymatic activation.

Abstract 1772: Cardiomyocyte Damage-Released S100A1 Protein Evokes A Proinflammatory Phenotype In Cardiac Fibroblasts

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
David Rohde ◽  
Melanie Boerries ◽  
Herzog Nicole ◽  
Gang Qiu ◽  
Philipp Ehlermann ◽  
...  
Keyword(s):  
Western Blotting ◽  
Immune Cells ◽  
Nuclear Translocation ◽  
Cardiac Fibroblasts ◽  
Innate Immune ◽  
Host Cells ◽  
Boyden Chamber ◽  
Innate Immune Cells ◽  
Danger Signal

Background: S100A1, a cardiomyocyte specific inotropic calcium sensor protein, is released from infarcted human myocardium in the extracellular environment and circulation, reaching peak serum levels (1–2 μM) 8–9 hours after clinical onset. As growing evidence indicates that S100 proteins can act as pre-existing danger signals triggering the innate immune system into action upon release from injured host cells, we hypothesized that damage-released S100A1 can act as a cardiac danger signal alerting innate immune cells. Methods and Results: Here we report for the first time that necrotic cardiomyocytes release S100A1 protein in vitro, which is exclusively internalized by cardiac fibroblasts (CFs) in a clathrin- and caveolin-independent manner as shown by IF. Internalized S100A1 specifically activated MAPKs/SAPKs (p38, ERK1/2 and JNK) resulting in nuclear translocation of p65 (NF-kB) as assessed by Western blotting, EMSA and IF. In turn, S100A1 triggered an inflammatory gene program in CFs including enhanced expression of adhesion molecules, integrins, chemokines and cytokines including I-CAM, V-CAM, CD11b/18, IL1-alpha, MCP-1, TNF-alpha, SDF-1 among others as obtained by RT-PCR, Western blotting and ELISA. This resulted in enhanced chemoattraction and adhesion of monocytotic and stem cells to S100A1-activated CF as shown by Boyden-chamber and adhesion assays. In line with their proinflammatory transition, S100A1-activated CFs exhibited decreased collagen-1/-3 expression and de-novo collagen production, enhanced collagenolytic MMP-9 abundance and activity and increased levels of the antiangiogenic matricellular factor thrombospondin-2 reflecting extracellular matrix net degradation. Importantly, the immun-modulatory and antifibrotic actions of S100A1 protein in vitro were restricted to CFs, RAGE independent and occurred at concentrations (0.1–1 μM) that were found in patients after AMI. Conclusion: Our in vitro results indicate that S100A1 has the properties of a pre-exisiting endogenous cardiomyocyte danger signal transforming cardiac fibroblasts into immunmodulatory cells that might recruit innate immune cells to the site of cardiac injury and link cardiomyocyte damage to post-MI inflammation.

scholarly journals PPAR Gamma and Viral Infections of the Brain

2021 ◽  
Vol 22 (16) ◽  
pp. 8876
Author(s):  
Pierre Layrolle ◽  
Pierre Payoux ◽  
Stéphane Chavanas
Keyword(s):  
Viral Infections ◽  
Ppar Gamma ◽  
Brain Parenchyma ◽  
Peroxisome Proliferator ◽  
Neural Cells ◽  
Peroxisome Proliferator Activated Receptor ◽  
Immunodeficiency Virus ◽  
Health And Disease ◽  
The Brain

Peroxisome Proliferator-Activated Receptor gamma (PPARγ) is a master regulator of metabolism, adipogenesis, inflammation and cell cycle, and it has been extensively studied in the brain in relation to inflammation or neurodegeneration. Little is known however about its role in viral infections of the brain parenchyma, although they represent the most frequent cause of encephalitis and are a major threat for the developing brain. Specific to viral infections is the ability to subvert signaling pathways of the host cell to ensure virus replication and spreading, as deleterious as the consequences may be for the host. In this respect, the pleiotropic role of PPARγ makes it a critical target of infection. This review aims to provide an update on the role of PPARγ in viral infections of the brain. Recent studies have highlighted the involvement of PPARγ in brain or neural cells infected by immunodeficiency virus 1, Zika virus, or human cytomegalovirus. They have provided a better understanding on PPARγ functions in the infected brain, and revealed that it can be a double-edged sword with respect to inflammation, viral replication, or neuronogenesis. They unraveled new roles of PPARγ in health and disease and could possibly help designing new therapeutic strategies.

scholarly journals Strategy of Human Cytomegalovirus To Escape Interferon Beta-Induced APOBEC3G Editing Activity

2018 ◽  
Vol 92 (19) ◽  
Author(s):  
Sara Pautasso ◽  
Ganna Galitska ◽  
Valentina Dell'Oste ◽  
Matteo Biolatti ◽  
Rachele Cagliani ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Hot Spots ◽  
Interferon Beta ◽  
Hcmv Infection ◽  
Viral Infections ◽  
Innate Immune ◽  
Mutational Robustness ◽  
Wide Range ◽  
Hcmv Replication ◽  
Apobec3 Family

ABSTRACTThe apolipoprotein B editing enzyme catalytic subunit 3 (APOBEC3) is a family of DNA cytosine deaminases that mutate and inactivate viral genomes by single-strand DNA editing, thus providing an innate immune response against a wide range of DNA and RNA viruses. In particular, APOBEC3A (A3A), a member of the APOBEC3 family, is induced by human cytomegalovirus (HCMV) in decidual tissues where it efficiently restricts HCMV replication, thereby acting as an intrinsic innate immune effector at the maternal-fetal interface. However, the widespread incidence of congenital HCMV infection implies that HCMV has evolved to counteract APOBEC3-induced mutagenesis through mechanisms that still remain to be fully established. Here, we have assessed gene expression and deaminase activity of various APOBEC3 gene family members in HCMV-infected primary human foreskin fibroblasts (HFFs). Specifically, we show that APOBEC3G (A3G) gene products and, to a lesser degree, those of A3F but not of A3A, are upregulated in HCMV-infected HFFs. We also show that HCMV-mediated induction of A3G expression is mediated by interferon beta (IFN-β), which is produced early during HCMV infection. However, knockout or overexpression of A3G does not affect HCMV replication, indicating that A3G is not a restriction factor for HCMV. Finally, through a bioinformatics approach, we show that HCMV has evolved mutational robustness against IFN-β by limiting the presence of A3G hot spots in essential open reading frames (ORFs) of its genome. Overall, our findings uncover a novel immune evasion strategy by HCMV with profound implications for HCMV infections.IMPORTANCEAPOBEC3 family of proteins plays a pivotal role in intrinsic immunity defense mechanisms against multiple viral infections, including retroviruses, through the deamination activity. However, the currently available data on APOBEC3 editing mechanisms upon HCMV infection remain unclear. In the present study, we show that particularly the APOBEC3G (A3G) member of the deaminase family is strongly induced upon infection with HCMV in fibroblasts and that its upregulation is mediated by IFN-β. Furthermore, we were able to demonstrate that neither A3G knockout nor A3G overexpression appears to modulate HCMV replication, indicating that A3G does not inhibit HCMV replication. This may be explained by HCMV escape strategy from A3G activity through depletion of the preferred nucleotide motifs (hot spots) from its genome. The results may shed light on antiviral potential of APOBEC3 activity during HCMV infection, as well as the viral counteracting mechanisms under A3G-mediated selective pressure.

Orthogonal genome-wide screens of bat cells identify MTHFD1 as a target of broad antiviral therapy

2021 ◽  
Vol 118 (39) ◽  
pp. e2104759118
Author(s):  
Danielle E. Anderson ◽  
Jin Cui ◽  
Qian Ye ◽  
Baoying Huang ◽  
Ya Tan ◽  
...  
Keyword(s):  
Antiviral Therapy ◽  
Influenza A ◽  
Secretory Pathway ◽  
Viral Infections ◽  
Innate Immune ◽  
Genome Wide ◽  
Genomic Studies ◽  
Independent Screening ◽  
Endocytosis Pathway ◽  
Lower Expression

Bats are responsible for the zoonotic transmission of several major viral diseases, including those leading to the 2003 SARS outbreak and likely the ongoing COVID-19 pandemic. While comparative genomics studies have revealed characteristic adaptations of the bat innate immune system, functional genomic studies are urgently needed to provide a foundation for the molecular dissection of the viral tolerance in bats. Here we report the establishment of genome-wide RNA interference (RNAi) and CRISPR libraries for the screening of the model megabat, Pteropus alecto. We used the complementary RNAi and CRISPR libraries to interrogate P. alecto cells for infection with two different viruses: mumps virus and influenza A virus, respectively. Independent screening results converged on the endocytosis pathway and the protein secretory pathway as required for both viral infections. Additionally, we revealed a general dependence of the C1-tetrahydrofolate synthase gene, MTHFD1, for viral replication in bat cells and human cells. The MTHFD1 inhibitor, carolacton, potently blocked replication of several RNA viruses, including SARS-CoV-2. We also discovered that bats have lower expression levels of MTHFD1 than humans. Our studies provide a resource for systematic inquiry into the genetic underpinnings of bat biology and a potential target for developing broad-spectrum antiviral therapy.

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