scholarly journals The dark side of the gut: Virome–host interactions in intestinal homeostasis and disease

2021 ◽  
Vol 218 (5) ◽  
Author(s):  
Yuhao Li ◽  
Scott A. Handley ◽  
Megan T. Baldridge
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Enteric Viruses ◽  
Dark Side ◽  
Animal Host ◽  
Host Interactions ◽  
Host Immune Responses ◽  
Complex Interactions ◽  
Intestinal Immune System ◽  
Viral Communities

The diverse enteric viral communities that infect microbes and the animal host collectively constitute the gut virome. Although recent advances in sequencing and analysis of metaviromes have revealed the complexity of the virome and facilitated discovery of new viruses, our understanding of the enteric virome is still incomplete. Recent studies have uncovered how virome–host interactions can contribute to beneficial or detrimental outcomes for the host. Understanding the complex interactions between enteric viruses and the intestinal immune system is a prerequisite for elucidating their role in intestinal diseases. In this review, we provide an overview of the enteric virome composition and summarize recent findings about how enteric viruses are sensed by and, in turn, modulate host immune responses during homeostasis and disease.

An appraisal of survival strategies

Parasitology ◽  
1984 ◽  
Vol 88 (4) ◽  
pp. 575-577 ◽  
Author(s):  
N. A. Mitchison
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Survival Strategies ◽  
Host Immune System ◽  
Cellular Immunology ◽  
Host Immune Responses ◽  
Host Defence System ◽  
Bio Engineering

Only a few years ago parasite immunology looked an unattractive subject better left to the dogged specialists. Parasites and hosts had been playing chess together for a million years, and there seemed little prospect of perturbing matters in favour of the host immune system. All that has changed, for three reasons. Firstly, we have learned how to grow at least some parasites in vitro, and prospects of doing so with others are encouraging. Secondly, progress in cellular immunology has revealed the sort of loopholes in the host defence system which parasites are likely to exploit: we are learning the questions which matter about parasites as antigens. Thirdly, and most importantly, molecular genetics is being brought to bear on parasites: we can now see a real, though long-term, prospect of manufacturing practicable vaccines through bio-engineering, and more immediately it gives us the tools needed to probe the host immune responses in the form of cloned antigens.

Leishmanial selenoproteins and the host immune system: towards new therapeutic strategies?

2020 ◽  
Vol 114 (7) ◽  
pp. 541-544
Author(s):  
Sajad Rashidi ◽  
Kurosh Kalantar ◽  
Paul Nguewa ◽  
Gholamreza Hatam
Keyword(s):  
Immune System ◽  
Adverse Effects ◽  
Immune Responses ◽  
Immune Cells ◽  
Therapeutic Strategies ◽  
Host Immune System ◽  
Host Immune Responses ◽  
Leishmania Parasites

Abstract Optimum levels of selenoproteins are essential for starting and managing the host immune responses against pathogens. According to the expression of selenoproteins in Leishmania parasites, and since high levels of selenoproteins lead to adverse effects on immune cells and their functions, Leishmania parasites might then express selenoproteins such as selenomethionine in their structure and/or secretions able to challenge the host immune system. Finally, this adaptation may lead to evasion of the parasite from the host immune system. The expression of selenoproteins in Leishmania parasites might then induce the development of infection. We therefore suggest these molecules as new therapeutic candidates for the treatment of leishmaniasis.

scholarly journals The Crossroads of Glycoscience, Infection, and Immunology

2021 ◽  
Vol 12 ◽  
Author(s):  
Tanya R. McKitrick ◽  
Margaret E. Ackerman ◽  
Robert M. Anthony ◽  
Clay S. Bennett ◽  
Michael Demetriou ◽  
...  
Keyword(s):  
Immune Responses ◽  
Host Response ◽  
Immune Cell ◽  
Microbial Infection ◽  
Surface Receptors ◽  
Host Interactions ◽  
Host Immune Responses ◽  
Immune Mediators ◽  
Immune Mediated ◽  
And Function

Advances in experimental capabilities in the glycosciences offer expanding opportunities for discovery in the broad areas of immunology and microbiology. These two disciplines overlap when microbial infection stimulates host immune responses and glycan structures are central in the processes that occur during all such encounters. Microbial glycans mediate host-pathogen interactions by acting as surface receptors or ligands, functioning as virulence factors, impeding host immune responses, or playing other roles in the struggle between host and microbe. In the context of the host, glycosylation drives cell–cell interactions that initiate and regulate the host response and modulates the effects of antibodies and soluble immune mediators. This perspective reports on a workshop organized jointly by the National Institute of Allergy and Infectious Diseases and the National Institute of Dental and Craniofacial Research in May 2020. The conference addressed the use of emerging glycoscience tools and resources to advance investigation of glycans and their roles in microbe-host interactions, immune-mediated diseases, and immune cell recognition and function. Future discoveries in these areas will increase fundamental scientific understanding and have the potential to improve diagnosis and treatment of infections and immune dysregulation.

scholarly journals Avian gut-associated lymphoid tissues and intestinal immune responses to Eimeria parasites.

1996 ◽  
Vol 9 (3) ◽  
pp. 349-360 ◽  
Author(s):  
H S Lillehoj ◽  
J M Trout
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Minor Role ◽  
Lymphoid Tissues ◽  
Cell Mediated Immunity ◽  
Limited Information ◽  
Effector Cells ◽  
Intestinal Immune System ◽  
Eimeria Spp ◽  
Coccidial Infection

Coccidiosis, an intestinal infection caused by intracellular protozoan parasites belonging to several different species of Eimeria, seriously impairs the growth and feed utilization of livestock and poultry. Host immune responses to coccidial infection are complex. Animals infected with Eimeria spp. produce parasite-specific antibodies in both the circulation and mucosal secretions. However, it appears that antibody-mediated responses play a minor role in protection against coccidiosis. Furthermore, there is increasing evidence that cell-mediated immunity plays a major role in resistance to infection. T lymphocytes appear to respond to coccidial infection through both cytokine production and a direct cytotoxic attack on infected cells. The exact mechanisms by which T cells eliminate the parasites, however, remain unclear. Although limited information is available on the intestinal immune system of chickens, gut lymphoid tissues have evolved specialized features that reflect their role as the first line of defense at mucosal surfaces, including both immunoregulatory cells and effector cells. This review summarizes our current understanding of the avian intestinal immune system and mucosal immune responses to Eimeria spp., providing an overview of the complex cellular and molecular events involved in intestinal immune responses to enteric pathogens.

scholarly journals Diet-Regulating Microbiota and Host Immune System in Liver Disease

2021 ◽  
Vol 22 (12) ◽  
pp. 6326
Author(s):  
Jung A. Eom ◽  
Goohyun Kwon ◽  
Nayeon Kim ◽  
Eunju Park ◽  
Sungmin Won ◽  
...  
Keyword(s):  
Immune System ◽  
Liver Disease ◽  
Immune Responses ◽  
Chronic Liver Disease ◽  
Chronic Liver ◽  
Host Immune System ◽  
Control Of Gene Expression ◽  
Cell Functions ◽  
Intestinal Immune System

The gut microbiota has been known to modulate the immune responses in chronic liver diseases. Recent evidence suggests that effects of dietary foods on health care and human diseases are related to both the immune reaction and the microbiome. The gut-microbiome and intestinal immune system play a central role in the control of bacterial translocation-induced liver disease. Dysbiosis, small intestinal bacterial overgrowth, translocation, endotoxemia, and the direct effects of metabolites are the main events in the gut-liver axis, and immune responses act on every pathways of chronic liver disease. Microbiome-derived metabolites or bacteria themselves regulate immune cell functions such as recognition or activation of receptors, the control of gene expression by epigenetic change, activation of immune cells, and the integration of cellular metabolism. Here, we reviewed recent reports about the immunologic role of gut microbiotas in liver disease, highlighting the role of diet in chronic liver disease.

scholarly journals Critical roles of bile acids in regulating intestinal mucosal immune responses

2021 ◽  
Vol 14 ◽  
pp. 175628482110180
Author(s):  
Ruicong Sun ◽  
Chunjin Xu ◽  
Baisui Feng ◽  
Xiang Gao ◽  
Zhanju Liu
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Bile Acids ◽  
Molecular Diversity ◽  
New Drugs ◽  
Daily Diet ◽  
Intestinal Immune System ◽  
Long Time ◽  
Inflammatory Bowel ◽  
Secondary Bile Acids

Bile acids are a class of cholesterol derivatives that have been known for a long time for their critical roles in facilitating the digestion and absorption of lipid from the daily diet. The transformation of primary bile acids produced by the liver to secondary bile acids appears under the action of microbiota in the intestine, greatly expanding the molecular diversity of the intestinal environment. With the discovery of several new receptors of bile acids and signaling pathways, bile acids are considered as a family of important metabolites that play pleiotropic roles in regulating many aspects of human overall health, especially in the maintenance of the microbiota homeostasis and the balance of the mucosal immune system in the intestine. Accordingly, disruption of the process involved in the metabolism or circulation of bile acids is implicated in many disorders that mainly affect the intestine, such as inflammatory bowel disease and colon cancer. In this review, we discuss the different metabolism profiles in diseases associated with the intestinal mucosa and the diverse roles of bile acids in regulating the intestinal immune system. Furthermore, we also summarize recent advances in the field of new drugs that target bile acid signaling and highlight the importance of bile acids as a new target for disease intervention.

scholarly journals The development of the mucosal immune system pre- and post-weaning: balancing regulatory and effector function

2005 ◽  
Vol 64 (4) ◽  
pp. 451-457 ◽  
Author(s):  
M. Bailey ◽  
K. Haverson ◽  
C. Inman ◽  
C. Harris ◽  
P. Jones ◽  
...  
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Young Animal ◽  
Intestinal Flora ◽  
Mucosal Immune System ◽  
Control Points ◽  
Critical Control Points ◽  
Intestinal Immune System ◽  
Secondary Function ◽  
Local Generation

The mucosal immune system fulfils the primary function of defence against potential pathogens that may enter across vulnerable surface epithelia. However, a secondary function of the intestinal immune system is to discriminate between pathogen-associated and ‘harmless’ antigens, expressing active responses against the former and tolerance to the latter. Control of immune responses appears to be an active process, involving local generation of IgA and of regulatory and/or regulated T lymphocytes. Two important periods of maximum exposure to novel antigens occur in the young animal, immediately after birth and at weaning. In both cases the antigenic composition of the intestinal contents can shift suddenly, as a result of a novel diet and of colonisation by novel strains and species of bacteria. Changes in lifestyles of man, and husbandry of animals, have resulted in weaning becoming much more abrupt than previously in evolution, increasing the number of antigens that must be simultaneously evaluated by neonates. Thus, birth and weaning are likely to represent hazard and critical control points in the development of appropriate responses to pathogens and harmless dietary and commensal antigens. Neonates are born with relatively undeveloped mucosal immune systems. At birth this factor may prevent both expression of active immune responses and development of tolerance. However, colonisation by intestinal flora expands the mucosal immune system in antigen-specific and non-specific ways. At weaning antibody to fed proteins can be detected, indicating active immune responses to fed proteins. It is proposed that under normal conditions the ability of the mucosal immune system to mount active responses to foreign antigens develops simultaneously with the ability to control and regulate such responses. Problems arise when one or other arm of the immune system develops inappropriately, resulting in inappropriate effector responses to harmless food proteins (allergy) or inadequate responses to pathogens (disease susceptibility).

scholarly journals Therapeutic Approaches for COVID-19 Based on the Interferon-mediated Immune Responses

2021 ◽  
Vol 16 ◽  
Author(s):  
Pouria Mosaddeghi ◽  
Farbod Shahabinezhad ◽  
Zahra Dehghani ◽  
Mitra Farahmandnejad ◽  
Mohammad Javad Taghipour ◽  
...  
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Genetic Similarity ◽  
The Body ◽  
Therapeutic Approaches ◽  
Host Immune Responses ◽  
Antiviral Responses ◽  
Interferon Induction ◽  
Optimum Approach ◽  
Novel Virus

Background: As the outbreak of COVID-19 has accelerated, an urgent need for finding strategies to combat the virus is growing. Thus, gaining more knowledge on the pathogenicity mechanism of SARS-CoV-2, the causing agent of COVID-19, and its interaction with the immune system is of utmost importance. Although this novel virus is not well known yet, its structural and genetic similarity with SARS-CoV as well as the comparable pattern of age-mortality relations suggest that some previous findings on SARS could be applicable for COVID-19. Objective: The aim of this study was to investigate the most important signaling pathways activated by coronaviruses to better understand the viral pathogenesis and host immune responses. Method: Here, a systems biology study was conducted on a SARS database. It was followed by a literature review on the cognate subject. Results: It was proved that interferons may possess a crucial role in the defense against coronavirus diseases. The literature supported the validity of the employed approach and the notion that interferon induction could play a key role in the body defense against coronavirus infections. Conclusion: Altogether, administration of interferons or interferon-inducing agents in a prophylactic manner or at early stages of the disease, could mimic the effective antiviral responses against SARS-CoV-2 and reduce the disease severity. At later stages of the disease, however, the balance of the immune reactions would be disrupted and the responses would shift toward immunopathogenic over-reactions, which could be exacerbated by interferon usage. Moderating the activity of the immune system by anti-inflammatory agents, might be the optimum approach in such conditions.

scholarly journals Enteric viruses evoke broad host immune responses resembling bacterial microbiome

2020 ◽  
Author(s):  
Dallari Simone ◽  
Heaney Thomas ◽  
Rosas-Villegas Adriana ◽  
Jessica A. Neil ◽  
Wong Serre-Yu ◽  
...  
Keyword(s):  
Immune Responses ◽  
Host Response ◽  
Transcriptional Profiling ◽  
Bacterial Species ◽  
Enteric Viruses ◽  
Viral Strain ◽  
Innate And Adaptive Immunity ◽  
Host Immune Responses ◽  
Flow Cytometric ◽  
Bacterial Microbiome

SUMMARYContributions of the viral component of the microbiome, the virome, to the development of innate and adaptive immunity are largely unknown. Here, we systematically defined the host response in mice to a panel of eukaryotic enteric viruses representing six different families. Most of these viruses asymptomatically infected the mice, the magnitude and duration of which was dependent on the microbiota. Flow cytometric and transcriptional profiling of mice mono-associated with these viruses unveiled general adaptations by the host, such as lymphocyte differentiation and IL-22 signatures in the intestine as well as numerous viral strain-specific responses that persist. Comparison with a dataset derived from analogous bacterial mono-association mice identified bacterial species that evoke an immune response comparable to the viruses we examined. These results expand an understanding of the immune space occupied by the enteric virome and underscore the importance of viral exposure events.

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