Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 9 de 9
Filter
1.
Int J Mol Sci ; 22(21)2021 Oct 21.
Article in English | MEDLINE | ID: covidwho-1480797

ABSTRACT

The intestinal barrier plays an extremely important role in maintaining the immune homeostasis of the gut and the entire body. It is made up of an intricate system of cells, mucus and intestinal microbiota. A complex system of proteins allows the selective permeability of elements that are safe and necessary for the proper nutrition of the body. Disturbances in the tightness of this barrier result in the penetration of toxins and other harmful antigens into the system. Such events lead to various digestive tract dysfunctions, systemic infections, food intolerances and autoimmune diseases. Pathogenic and probiotic bacteria, and the compounds they secrete, undoubtedly affect the properties of the intestinal barrier. The discovery of zonulin, a protein with tight junction regulatory activity in the epithelia, sheds new light on the understanding of the role of the gut barrier in promoting health, as well as the formation of diseases. Coincidentally, there is an increasing number of reports on treatment methods that target gut microbiota, which suggests that the prevention of gut-barrier defects may be a viable approach for improving the condition of COVID-19 patients. Various bacteria-intestinal barrier interactions are the subject of this review, aiming to show the current state of knowledge on this topic and its potential therapeutic applications.


Subject(s)
Bacterial Infections/therapy , Haptoglobins/metabolism , Intestinal Mucosa/metabolism , Probiotics/therapeutic use , Protein Precursors/metabolism , Anti-Bacterial Agents/therapeutic use , Bacterial Infections/drug therapy , Bacterial Infections/pathology , Bacterial Physiological Phenomena , Gastrointestinal Microbiome , Humans , Intestinal Mucosa/microbiology , Mucus/metabolism , Tight Junctions/metabolism
2.
Front Immunol ; 12: 636966, 2021.
Article in English | MEDLINE | ID: covidwho-1438414

ABSTRACT

Since 2003, the world has been confronted with three new betacoronaviruses that cause human respiratory infections: SARS-CoV, which causes severe acute respiratory syndrome (SARS), MERS-CoV, which causes Middle East respiratory syndrome (MERS), and SARS-CoV-2, which causes Coronavirus Disease 2019 (COVID-19). The mechanisms of coronavirus transmission and dissemination in the human body determine the diagnostic and therapeutic strategies. An important problem is the possibility that viral particles overcome tissue barriers such as the intestine, respiratory tract, blood-brain barrier, and placenta. In this work, we will 1) consider the issue of endocytosis and the possibility of transcytosis and paracellular trafficking of coronaviruses across tissue barriers with an emphasis on the intestinal epithelium; 2) discuss the possibility of antibody-mediated transcytosis of opsonized viruses due to complexes of immunoglobulins with their receptors; 3) assess the possibility of the virus transfer into extracellular vesicles during intracellular transport; and 4) describe the clinical significance of these processes. Models of the intestinal epithelium and other barrier tissues for in vitro transcytosis studies will also be briefly characterized.


Subject(s)
Endocytosis , Intestinal Mucosa/virology , SARS-CoV-2/metabolism , Antibodies, Viral/metabolism , Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , COVID-19/drug therapy , COVID-19/transmission , COVID-19/virology , Clinical Trials as Topic , Endocytosis/drug effects , Humans , Intestinal Mucosa/metabolism , Models, Biological , SARS-CoV-2/drug effects , SARS-CoV-2/immunology , Tight Junctions/metabolism , Tight Junctions/virology , Transcytosis/drug effects , Virus Attachment
3.
Signal Transduct Target Ther ; 6(1): 337, 2021 09 06.
Article in English | MEDLINE | ID: covidwho-1402050

ABSTRACT

SARS-CoV-2 has been reported to show a capacity for invading the brains of humans and model animals. However, it remains unclear whether and how SARS-CoV-2 crosses the blood-brain barrier (BBB). Herein, SARS-CoV-2 RNA was occasionally detected in the vascular wall and perivascular space, as well as in brain microvascular endothelial cells (BMECs) in the infected K18-hACE2 transgenic mice. Moreover, the permeability of the infected vessel was increased. Furthermore, disintegrity of BBB was discovered in the infected hamsters by administration of Evans blue. Interestingly, the expression of claudin5, ZO-1, occludin and the ultrastructure of tight junctions (TJs) showed unchanged, whereas, the basement membrane was disrupted in the infected animals. Using an in vitro BBB model that comprises primary BMECs with astrocytes, SARS-CoV-2 was found to infect and cross through the BMECs. Consistent with in vivo experiments, the expression of MMP9 was increased and collagen IV was decreased while the markers for TJs were not altered in the SARS-CoV-2-infected BMECs. Besides, inflammatory responses including vasculitis, glial activation, and upregulated inflammatory factors occurred after SARS-CoV-2 infection. Overall, our results provide evidence supporting that SARS-CoV-2 can cross the BBB in a transcellular pathway accompanied with basement membrane disrupted without obvious alteration of TJs.


Subject(s)
Basement Membrane/metabolism , Blood-Brain Barrier/metabolism , COVID-19/metabolism , SARS-CoV-2/metabolism , Tight Junctions/metabolism , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Animals , Basement Membrane/pathology , Basement Membrane/virology , Blood-Brain Barrier/pathology , Blood-Brain Barrier/virology , COVID-19/genetics , COVID-19/pathology , Chlorocebus aethiops , Disease Models, Animal , Humans , Matrix Metalloproteinase 9/genetics , Matrix Metalloproteinase 9/metabolism , Mice , Mice, Transgenic , SARS-CoV-2/genetics , Tight Junctions/genetics , Tight Junctions/pathology , Tight Junctions/virology , Vero Cells
4.
Front Immunol ; 12: 708149, 2021.
Article in English | MEDLINE | ID: covidwho-1337643

ABSTRACT

Microbial translocation (MT) and intestinal damage (ID) are poorly explored in COVID-19. Aims were to assess whether alteration of gut permeability and cell integrity characterize COVID-19 patients, whether it is more pronounced in severe infections and whether it influences the development of subsequent bloodstream infection (BSI). Furthermore, we looked at the potential predictive role of TM and ID markers on Intensive Care Unit (ICU) admission and in-hospital mortality. Over March-July 2020, 45 COVID-19 patients were enrolled. Markers of MT [LPB (Lipopolysacharide Binding Protein) and EndoCab IgM] and ID [I-FABP (Intestinal Fatty Acid Binding Protein)] were evaluated at COVID-19 diagnosis and after 7 days. As a control group, age- and gender-matched healthy donors (HDs) enrolled during the same study period were included. Median age was 66 (56-71) years. Twenty-one (46.6%) were admitted to ICU and mortality was 22% (10/45). Compared to HD, a high degree of MT and ID was observed. ICU patients had higher levels of MT, but not of ID, than non-ICU ones. Likewise, patients with BSI had lower EndoCab IgM than non-BSI. Interestingly, patients with high degree of MT and low ID were likely to be admitted to ICU (AUC 0.822). Patients with COVID-19 exhibited high level of MT, especially subjects admitted to ICU. COVID-19 is associated with gut permeability.


Subject(s)
COVID-19/metabolism , Intestinal Mucosa/metabolism , SARS-CoV-2/physiology , Acute-Phase Proteins/metabolism , Aged , Biomarkers/metabolism , COVID-19/diagnosis , COVID-19/mortality , COVID-19/pathology , Carrier Proteins/metabolism , Disease Progression , Fatty Acid-Binding Proteins/metabolism , Female , Humans , Intensive Care Units , Intestinal Mucosa/pathology , Male , Membrane Glycoproteins/metabolism , Middle Aged , Predictive Value of Tests , Prognosis , Survival Analysis , Tight Junctions/metabolism
5.
Front Immunol ; 12: 686240, 2021.
Article in English | MEDLINE | ID: covidwho-1285294

ABSTRACT

A disruption of the crosstalk between the gut and the lung has been implicated as a driver of severity during respiratory-related diseases. Lung injury causes systemic inflammation, which disrupts gut barrier integrity, increasing the permeability to gut microbes and their products. This exacerbates inflammation, resulting in positive feedback. We aimed to test whether severe Coronavirus disease 2019 (COVID-19) is associated with markers of disrupted gut permeability. We applied a multi-omic systems biology approach to analyze plasma samples from COVID-19 patients with varying disease severity and SARS-CoV-2 negative controls. We investigated the potential links between plasma markers of gut barrier integrity, microbial translocation, systemic inflammation, metabolome, lipidome, and glycome, and COVID-19 severity. We found that severe COVID-19 is associated with high levels of markers of tight junction permeability and translocation of bacterial and fungal products into the blood. These markers of disrupted intestinal barrier integrity and microbial translocation correlate strongly with higher levels of markers of systemic inflammation and immune activation, lower levels of markers of intestinal function, disrupted plasma metabolome and glycome, and higher mortality rate. Our study highlights an underappreciated factor with significant clinical implications, disruption in gut functions, as a potential force that may contribute to COVID-19 severity.


Subject(s)
COVID-19/immunology , Gastrointestinal Microbiome/immunology , Inflammation/immunology , Intestines/physiology , SARS-CoV-2/physiology , Female , Glycomics , Haptoglobins/metabolism , Humans , Lipidomics , Male , Metabolomics , Middle Aged , Permeability , Protein Precursors/metabolism , Tight Junctions/metabolism
6.
PLoS One ; 16(6): e0251955, 2021.
Article in English | MEDLINE | ID: covidwho-1262543

ABSTRACT

Newly emerged SARS-CoV-2 is the cause of an ongoing global pandemic leading to severe respiratory disease in humans. SARS-CoV-2 targets epithelial cells in the respiratory tract and lungs, which can lead to amplified chloride secretion and increased leak across epithelial barriers, contributing to severe pneumonia and consolidation of the lungs as seen in many COVID-19 patients. There is an urgent need for a better understanding of the molecular aspects that contribute to SARS-CoV-2-induced pathogenesis and for the development of approaches to mitigate these damaging pathologies. The multifunctional SARS-CoV-2 Envelope (E) protein contributes to virus assembly/egress, and as a membrane protein, also possesses viroporin channel properties that may contribute to epithelial barrier damage, pathogenesis, and disease severity. The extreme C-terminal (ECT) sequence of E also contains a putative PDZ-domain binding motif (PBM), similar to that identified in the E protein of SARS-CoV-1. Here, we screened an array of GST-PDZ domain fusion proteins using either a biotin-labeled WT or mutant ECT peptide from the SARS-CoV-2 E protein. Notably, we identified a singular specific interaction between the WT E peptide and the second PDZ domain of human Zona Occludens-1 (ZO1), one of the key regulators of TJ formation/integrity in all epithelial tissues. We used homogenous time resolve fluorescence (HTRF) as a second complementary approach to further validate this novel modular E-ZO1 interaction. We postulate that SARS-CoV-2 E interacts with ZO1 in infected epithelial cells, and this interaction may contribute, in part, to tight junction damage and epithelial barrier compromise in these cell layers leading to enhanced virus spread and severe dysfunction that leads to morbidity. Prophylactic/therapeutic intervention targeting this virus-host interaction may effectively reduce airway and/or gastrointestinal barrier damage and mitigate virus spread.


Subject(s)
COVID-19/metabolism , COVID-19/virology , Coronavirus Envelope Proteins/metabolism , SARS-CoV-2/metabolism , Zonula Occludens-1 Protein/metabolism , COVID-19/pathology , Host-Pathogen Interactions , Humans , PDZ Domains , Protein Binding , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , SARS-CoV-2/isolation & purification , Tight Junctions/metabolism
7.
JCI Insight ; 6(4)2021 02 22.
Article in English | MEDLINE | ID: covidwho-1105583

ABSTRACT

An intact lung epithelial barrier is essential for lung homeostasis. The Na+, K+-ATPase (NKA), primarily serving as an ion transporter, also regulates epithelial barrier function via modulation of tight junctions. However, the underlying mechanism is not well understood. Here, we show that overexpression of the NKA ß1 subunit upregulates the expression of tight junction proteins, leading to increased alveolar epithelial barrier function by an ion transport-independent mechanism. Using IP and mass spectrometry, we identified a number of unknown protein interactions of the ß1 subunit, including a top candidate, myotonic dystrophy kinase-related cdc42-binding kinase α (MRCKα), which is a protein kinase known to regulate peripheral actin formation. Using a doxycycline-inducible gene expression system, we demonstrated that MRCKα and its downstream activation of myosin light chain is required for the regulation of alveolar barrier function by the NKA ß1 subunit. Importantly, MRCKα is expressed in both human airways and alveoli and has reduced expression in patients with acute respiratory distress syndrome (ARDS), a lung illness that can be caused by multiple direct and indirect insults, including the infection of influenza virus and SARS-CoV-2. Our results have elucidated a potentially novel mechanism by which NKA regulates epithelial tight junctions and have identified potential drug targets for treating ARDS and other pulmonary diseases that are caused by barrier dysfunction.


Subject(s)
Myotonin-Protein Kinase/metabolism , Sodium-Potassium-Exchanging ATPase/metabolism , Tight Junctions/metabolism , Alveolar Epithelial Cells/cytology , Alveolar Epithelial Cells/metabolism , Animals , HEK293 Cells , Humans , Myotonin-Protein Kinase/genetics , Primary Cell Culture , Rats , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Respiratory Distress Syndrome/pathology , Respiratory Distress Syndrome/virology , SARS-CoV-2/pathogenicity , Sodium-Potassium-Exchanging ATPase/genetics
8.
PLoS One ; 15(12): e0242536, 2020.
Article in English | MEDLINE | ID: covidwho-965821

ABSTRACT

Retinoic acid (RA) has been shown to improve epithelial and endothelial barrier function and development and even suppress damage inflicted by inflammation on these barriers through regulating immune cell activity. This paper thus sought to determine whether RA could improve baseline barrier function and attenuate TNF-α-induced barrier leak in the human bronchial epithelial cell culture model, 16HBE14o- (16HBE). We show for the first time that RA increases baseline barrier function of these cell layers indicated by an 89% increase in transepithelial electrical resistance (TER) and 22% decrease in 14C-mannitol flux. A simultaneous, RA-induced 70% increase in claudin-4 attests to RA affecting the tight junctional (TJ) complex itself. RA was also effective in alleviating TNF-α-induced 16HBE barrier leak, attenuating 60% of the TNF-α-induced leak to 14C-mannitol and 80% of the leak to 14C-inulin. Interleukin-6-induced barrier leak was also reduced by RA. Treatment of 16HBE cell layers with TNF-α resulted in dramatic decrease in immunostaining for occludin and claudin-4, as well as a downward "band-shift" in occludin Western immunoblots. The presence of RA partially reversed TNF-α's effects on these select TJ proteins. Lastly, RA completely abrogated the TNF-α-induced increase in ERK-1,2 phosphorylation without significantly decreasing the TNF-driven increase in total ERK-1,2. This study suggests RA could be effective as a prophylactic agent in minimizing airway barrier leak and as a therapeutic in preventing leak triggered by inflammatory cascades. Given the growing literature suggesting a "cytokine storm" may be related to COVID-19 morbidity, RA may be a useful adjuvant for use with anti-viral therapies.


Subject(s)
Bronchi/drug effects , Respiratory Mucosa/drug effects , Tretinoin/pharmacology , Tumor Necrosis Factor-alpha/metabolism , Anti-Inflammatory Agents/pharmacology , Bronchi/cytology , Bronchi/metabolism , Cell Line , Humans , Inflammation/drug therapy , Inflammation/metabolism , Permeability/drug effects , Respiratory Mucosa/cytology , Respiratory Mucosa/metabolism , Tight Junctions/drug effects , Tight Junctions/metabolism
9.
Microbes Infect ; 22(10): 592-597, 2020.
Article in English | MEDLINE | ID: covidwho-744191

ABSTRACT

The Envelope (E) protein of SARS-CoV-2 is the most enigmatic protein among the four structural ones. Most of its current knowledge is based on the direct comparison to the SARS E protein, initially mistakenly undervalued and subsequently proved to be a key factor in the ER-Golgi localization and in tight junction disruption. We compared the genomic sequences of E protein of SARS-CoV-2, SARS-CoV and the closely related genomes of bats and pangolins obtained from the GISAID and GenBank databases. When compared to the known SARS E protein, we observed a significant difference in amino acid sequence in the C-terminal end of SARS-CoV-2 E protein. Subsequently, in silico modelling analyses of E proteins conformation and docking provide evidences of a strengthened binding of SARS-CoV-2 E protein with the tight junction-associated PALS1 protein. Based on our computational evidences and on data related to SARS-CoV, we believe that SARS-CoV-2 E protein interferes more stably with PALS1 leading to an enhanced epithelial barrier disruption, amplifying the inflammatory processes, and promoting tissue remodelling. These findings raise a warning on the underestimated role of the E protein in the pathogenic mechanism and open the route to detailed experimental investigations.


Subject(s)
COVID-19/metabolism , Membrane Proteins/chemistry , Nucleoside-Phosphate Kinase/chemistry , SARS-CoV-2/chemistry , Tight Junctions/chemistry , Viral Envelope Proteins/chemistry , Amino Acid Sequence , Animals , COVID-19/genetics , Chiroptera/virology , Databases, Genetic , Humans , Membrane Proteins/genetics , Membrane Proteins/metabolism , Molecular Dynamics Simulation , Nucleoside-Phosphate Kinase/genetics , Nucleoside-Phosphate Kinase/metabolism , Pangolins/virology , SARS Virus/chemistry , SARS Virus/genetics , SARS Virus/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Tight Junctions/metabolism , Viral Envelope Proteins/genetics , Viral Envelope Proteins/metabolism
SELECTION OF CITATIONS
SEARCH DETAIL
...