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2.
Blood Adv ; 6(13): 3884-3898, 2022 07 12.
Article in English | MEDLINE | ID: covidwho-1923509

ABSTRACT

Mild thrombocytopenia, changes in platelet gene expression, enhanced platelet functionality, and presence of platelet-rich thrombi in the lung have been associated with thromboinflammatory complications of patients with COVID-19. However, whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gets internalized by platelets and directly alters their behavior and function in infected patients remains elusive. Here, we investigated platelet parameters and the presence of viral material in platelets from a prospective cohort of 29 patients with severe COVID-19 admitted to an intensive care unit. A combination of specific assays, tandem mass spectrometry, and flow cytometry indicated high levels of protein and lipid platelet activation markers in the plasma from patients with severe COVID-19 associated with an increase of proinflammatory cytokines and leukocyte-platelets interactions. Platelets were partly desensitized, as shown by a significant reduction of αIIbß3 activation and granule secretion in response to stimulation and a decrease of surface GPVI, whereas plasma from patients with severe COVID-19 potentiated washed healthy platelet aggregation response. Transmission electron microscopy indicated the presence of SARS-CoV-2 particles in a significant fraction of platelets as confirmed by immunogold labeling and immunofluorescence imaging of Spike and nucleocapsid proteins. Compared with platelets from healthy donors or patients with bacterial sepsis, platelets from patients with severe COVID-19 exhibited enlarged intracellular vesicles and autophagolysosomes. They had large LC3-positive structures and increased levels of LC3II with a co-localization of LC3 and Spike, suggesting that platelets can digest SARS-CoV-2 material by xenophagy in critically ill patients. Altogether, these data show that during severe COVID-19, platelets get activated, become partly desensitized, and develop a selective autophagy response.


Subject(s)
COVID-19 , Humans , Macroautophagy , Platelet Activation , Prospective Studies , SARS-CoV-2
3.
Viruses ; 14(5)2022 05 15.
Article in English | MEDLINE | ID: covidwho-1884377

ABSTRACT

In this study, we investigated the correlation between the mechanism involved in porcine epidemic diarrhea virus (PEDV) replication and autophagic flux. In this study, we found that as PEDV replicated, production of LC3-II was significantly induced up to 24 h post-infection (hpi). Interestingly, although there was significant production of LC3-II, greater p62 accumulation was simultaneously found. Pretreatment with rapamycin significantly induced PEDV replication, but autolysosome formation was reduced. These results were confirmed by the evaluation of ATG5/ATG12 and LAMP1/LAMP2. Taken together, we conclude that PEDV infection induces autophagosome formation but inhibits autolysosome formation during replication.


Subject(s)
Autophagosomes/metabolism , Porcine epidemic diarrhea virus , Animals , Autophagosomes/genetics , Chlorocebus aethiops , Lysosomes/genetics , Lysosomes/metabolism , Macroautophagy , Porcine epidemic diarrhea virus/immunology , Swine , Vero Cells
4.
Autophagy ; 17(8): 2048-2050, 2021 08.
Article in English | MEDLINE | ID: covidwho-1393103

ABSTRACT

TMEM41B and VMP1, two endoplasmic reticulum (ER)-resident transmembrane proteins, play important roles in regulating the formation of lipid droplets (LDs), autophagy initiation, and viral infection. However, the biochemical functions of TMEM41B and VMP1 are unclear. A lipids distribution screen suggested TMEM41B and VMP1 are critical to the normal distribution of cholesterol and phosphatidylserine. Biochemical analyses unveiled that TMEM41B and VMP1 have scramblase activity. These findings shed light on the mechanism by which TMEM41B and VMP1 regulate LD formation, lipids distribution, macroautophagy, and viral infection.


Subject(s)
Autophagy/physiology , Membrane Proteins/metabolism , Phospholipid Transfer Proteins/metabolism , Animals , Autophagosomes/metabolism , Humans , Macroautophagy/physiology
5.
Exp Cell Res ; 396(1): 112276, 2020 11 01.
Article in English | MEDLINE | ID: covidwho-752714

ABSTRACT

Autophagy is an evolutionary conserved catabolic process devoted to the removal of unnecessary and harmful cellular components. In its general form, autophagy governs cellular lifecycle through the formation of double membrane vesicles, termed autophagosomes, that enwrap and deliver unwanted intracellular components to lysosomes. In addition to this omniscient role, forms of selective autophagy, relying on specialized receptors for cargo recognition, exert fine-tuned control over cellular homeostasis. In this regard, xenophagy plays a pivotal role in restricting the replication of intracellular pathogens, thus acting as an ancient innate defense system against infections. Recently, selective autophagy of the endoplasmic reticulum (ER), more simply ER-phagy, has been uncovered as a critical mechanism governing ER network shape and function. Six ER-resident proteins have been characterized as ER-phagy receptors and their orchestrated function enables ER homeostasis and turnover overtime. Unfortunately, ER is also the preferred site for viral replication and several viruses hijack ER machinery for their needs. Thus, it is not surprising that some ER-phagy receptors can act to counteract viral replication and minimize the spread of infection throughout the organism. On the other hand, evolutionary pressure has armed pathogens with strategies to evade and subvert xenophagy and ER-phagy. Although ER-phagy biology is still in its infancy, the present review aims to summarize recent ER-phagy literature, with a special focus on its role in counteracting viral infections. Moreover, we aim to offer some hints for future targeted approaches to counteract host-pathogen interactions by modulating xenophagy and ER-phagy pathways.


Subject(s)
Autophagosomes/immunology , Bacterial Infections/immunology , Endoplasmic Reticulum/immunology , Host-Pathogen Interactions/immunology , Macroautophagy/immunology , Virus Diseases/immunology , Autophagosomes/metabolism , Bacteria/immunology , Bacterial Infections/genetics , Bacterial Infections/microbiology , Endoplasmic Reticulum/genetics , Endoplasmic Reticulum/microbiology , Endoplasmic Reticulum/virology , Endoplasmic Reticulum Stress/genetics , Endoplasmic Reticulum Stress/immunology , Homeostasis/genetics , Homeostasis/immunology , Host-Pathogen Interactions/genetics , Humans , Immunity, Innate , Lysosomes/immunology , Lysosomes/metabolism , Macroautophagy/genetics , Virus Diseases/genetics , Virus Diseases/virology , Viruses/immunology
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