The role of the innate immune system on pulmonary infections

2019 ◽  
Vol 400 (4) ◽  
pp. 443-456 ◽  
Author(s):  
Michelle Galeas-Pena ◽  
Nathaniel McLaughlin ◽  
Derek Pociask
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Innate Immune Response ◽  
Innate Immune System ◽  
Adaptive Immune System ◽  
Innate Immune ◽  
Resistant Bacteria ◽  
Upper Respiratory Tract ◽  
Phagocytic Cells ◽  
Mucus Production

Abstract Inhalation is required for respiration and life in all vertebrates. This process is not without risk, as it potentially exposes the host to environmental pathogens with every breath. This makes the upper respiratory tract one of the most common routes of infection and one of the leading causes of morbidity and mortality in the world. To combat this, the lung relies on the innate immune defenses. In contrast to the adaptive immune system, the innate immune system does not require sensitization, previous exposure or priming to attack foreign particles. In the lung, the innate immune response starts with the epithelial barrier and mucus production and is reinforced by phagocytic cells and T cells. These cells are vital for the production of cytokines, chemokines and anti-microbial peptides that are critical for clearance of infectious agents. In this review, we discuss all aspects of the innate immune response, with a special emphasis on ways to target aspects of the immune response to combat antibiotic resistant bacteria.

scholarly journals Insights into Innate Immune Response Against SARS-CoV-2 Infection

2021 ◽  
Vol 29 (3) ◽  
pp. 255-269
Author(s):  
Adina Huțanu ◽  
Anca Meda Georgescu ◽  
Akos Vince Andrejkovits ◽  
William Au ◽  
Minodora Dobreanu
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Innate Immune Response ◽  
Innate Immune System ◽  
Time Course ◽  
Adaptive Immune Response ◽  
Innate Immune ◽  
Interferon Response ◽  
Humoral Factors ◽  
Key Steps

Abstract The innate immune system is mandatory for the activation of antiviral host defense and eradication of the infection. In this regard, dendritic cells, natural killer cells, macrophages, neutrophils representing the cellular component, and cytokines, interferons, complement or Toll-Like Receptors, representing the mediators of unspecific response act together for both activation of the adaptive immune response and viral clearance. Of great importance is the proper functioning of the innate immune response from the very beginning. For instance, in the early stages of viral infection, the defective interferon response leads to uncontrolled viral replication and pathogen evasion, while hypersecretion during the later stages of infection generates hyperinflammation. This cascade activation of systemic inflammation culminates with cytokine storm syndrome and hypercoagulability state, due to a close interconnection between them. Thus an unbalanced reaction, either under- or over- stimulation of the innate immune system will lead to an uncoordinated response and unfavorable disease outcomes. Since both cellular and humoral factors are involved in the time-course of the innate immune response, in this review we aimed to address their gradual involvement in the antiviral response with emphasis on key steps in SARS-CoV-2 infection.

Basic Immunology

2019 ◽  
Author(s):  
Jonathan Lambourne ◽  
Ruaridh Buchanan
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Epithelial Cells ◽  
Immune Cells ◽  
Innate Immune System ◽  
Adaptive Immune System ◽  
Lymphoid Organs ◽  
Innate Immune ◽  
Adaptive Immune ◽  
Pathogen Entry

There are four major components of the immune system. These include: 1. mechanical barriers to pathogen entry. 2. the innate immune system. 3. the adaptive immune system. 4. the lymphoid organs. Mechanical barriers include skin and mucous membranes and tight junctions between epithelial cells prevent pathogen entry. Breaches can be iatrogenic, for example, IV lines, surgical wounds, and mucositis, and are a large source of healthcare- associated infections. The innate immune system provides the first internal line of defence, as well as initiating and shaping the adaptive immune response. The innate system comprises a range of responses: phagocytosis by neutrophils and macrophages (guided in part by the adaptive immune system), the complement cascade, and the release of antimicrobial peptides by epithelial cells (e.g. defensins, cathelicidin). The adaptive immune system includes both humoral (antibody- mediated) and cell-mediated responses. It is capable of greater diversity and specificity than the innate immune system, and can develop memory to pathogens and provide increased protection on re-exposure. Immune cells are divided into myeloid cells (neutrophils, eosinophils, basophils, mast cells, and monocytes/macrophages) and lymphoid cells (B, T, and NK cells). These all originate in the bone marrow from pluripotent haematopoietic stem cells. The lymphoid organs include the spleen, the lymph nodes, and mucosal-associated lymphoid tissues—which respond to antigens in the blood, tissues, and epithelial surfaces respectively. The three main ‘professional’ phagocytes are macrophages, dendritic cells, and neutrophils. They are similar with respect to how they recognize pathogens, but differ in their principal location and effector functions. Phagocytes express an array of Pattern Recognition Receptors (PRRs) e.g. Toll-like receptors and lectins (proteins that bind carbohydrates). PRRs recognize Pathogen- Associated Molecular Patterns (PAMPs)— elements which are conserved across species, such as cell-surface glycoproteins and nucleic acid sequences. Though limited in number, PRRs have evolved to recognize a huge array of pathogens. Binding of PRRs to PAMPs enhances phagocytosis. Macrophages are tissue-resident phagocytes, initiating and co-ordinating the local immune response. The cytokines and chemokines they produce cause vasodilation and alter the expression of endothelial cell adhesion factors, recruiting circulating immune cells.

scholarly journals Mycobacterial infection induces a specific human innate immune response

2015 ◽  
Author(s):  
John D Blischak ◽  
Ludovic Tailleux ◽  
Amy Mitrano ◽  
Luis B Barreiro ◽  
Yoav Gilad
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Innate Immune Response ◽  
Transcriptional Response ◽  
Adaptive Immune System ◽  
Mycobacterial Infection ◽  
Innate Immune ◽  
Pathogen Infection ◽  
General Response ◽  
Candidate Loci

The innate immune system provides the first response to pathogen infection and orchestrates the activation of the adaptive immune system. Though a large component of the innate immune response is common to all infections, pathogen-specific responses have been documented as well. The innate immune response is thought to be especially critical for fighting infection with Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB). While TB can be deadly, only 5-10% of individuals infected with MTB develop active disease. The risk for disease susceptibility is, at least partly, heritable. Studies of inter-individual variation in the innate immune response to MTB infection may therefore shed light on the genetic basis for variation in susceptibility to TB. Yet, to date, we still do not know which properties of the innate immune response are specific to MTB infection and which represent a general response to pathogen infection. To begin addressing this gap, we infected macrophages with eight different bacteria, including different MTB strains and related mycobacteria, and studied the transcriptional response to infection. Although the ensued gene regulatory responses were largely consistent across the bacterial infection treatments, we were able to identify a novel subset of genes whose regulation was affected specifically by infection with mycobacteria. Genetic variants that are associated with regulatory differences in these genes should be considered candidate loci for explaining inter-individual susceptibility TB.

scholarly journals The Yin and Yang of Innate Immunity in Stroke

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaomeng Xu ◽  
Yongjun Jiang
Keyword(s):  
Immune Response ◽  
Innate Immunity ◽  
Ischemic Stroke ◽  
Immune System ◽  
Innate Immune Response ◽  
Time Window ◽  
Adaptive Immune System ◽  
Innate Immune ◽  
Yin And Yang ◽  
Molecular Patterns

Immune system plays an elementary role in the pathophysiological progress of ischemic stroke. It consists of innate and adaptive immune system. Activated within minutes after ischemic onset, innate immunity is responsible for the elimination of necrotic cells and tissue repair, while it is critically involved in the initiation and amplification of poststroke inflammation that amplifies ischemic damage to the brain tissue. Innate immune response requires days to be fully developed, providing a considerable time window for therapeutic intervention, suggesting prospect of novel immunomodulatory therapies against poststroke inflammation-induced brain injury. However, obstacles still exist and a comprehensive understanding of ischemic stroke and innate immune reaction is essential. In this review, we highlighted the current experimental and clinical data depicting the innate immune response following ischemic stroke, mainly focusing on the recognition of damage-associated molecular patterns, activation and recruitment of innate immune cells, and involvement of various cytokines. In addition, clinical trials targeting innate immunity were also documented regardless of the outcome, stressing the requirements for further investigation.

scholarly journals Modeling Virus-Induced Inflammation in Zebrafish: A Balance Between Infection Control and Excessive Inflammation

2021 ◽  
Vol 12 ◽  
Author(s):  
Con Sullivan ◽  
Brandy-Lee Soos ◽  
Paul J. Millard ◽  
Carol H. Kim ◽  
Benjamin L. King
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Inflammatory Response ◽  
Viral Infection ◽  
Innate Immune Response ◽  
Innate Immune System ◽  
Innate Immune ◽  
Zebrafish Model ◽  
Infection Models

The inflammatory response to viral infection in humans is a dynamic process with complex cell interactions that are governed by the immune system and influenced by both host and viral factors. Due to this complexity, the relative contributions of the virus and host factors are best studied in vivo using animal models. In this review, we describe how the zebrafish (Danio rerio) has been used as a powerful model to study host-virus interactions and inflammation by combining robust forward and reverse genetic tools with in vivo imaging of transparent embryos and larvae. The innate immune system has an essential role in the initial inflammatory response to viral infection. Focused studies of the innate immune response to viral infection are possible using the zebrafish model as there is a 4-6 week timeframe during development where they have a functional innate immune system dominated by neutrophils and macrophages. During this timeframe, zebrafish lack a functional adaptive immune system, so it is possible to study the innate immune response in isolation. Sequencing of the zebrafish genome has revealed significant genetic conservation with the human genome, and multiple studies have revealed both functional conservation of genes, including those critical to host cell infection and host cell inflammatory response. In addition to studying several fish viruses, zebrafish infection models have been developed for several human viruses, including influenza A, noroviruses, chikungunya, Zika, dengue, herpes simplex virus type 1, Sindbis, and hepatitis C virus. The development of these diverse viral infection models, coupled with the inherent strengths of the zebrafish model, particularly as it relates to our understanding of macrophage and neutrophil biology, offers opportunities for far more intensive studies aimed at understanding conserved host responses to viral infection. In this context, we review aspects relating to the evolution of innate immunity, including the evolution of viral pattern recognition receptors, interferons and interferon receptors, and non-coding RNAs.

Innate vs acquired immunity

2013 ◽  
Author(s):  
Reinhard E. Voll ◽  
Barbara M. Bröker
Keyword(s):  
Immune System ◽  
Immune Cells ◽  
Innate Immune System ◽  
Adaptive Immune System ◽  
Life Cycles ◽  
Innate Immune ◽  
Inflammatory Rheumatic Diseases ◽  
Phagocytic Cells ◽  
Adaptive Immune ◽  
Adaptive Immune Cells

The innate and the adaptive immune system efficiently cooperate to protect us from infections. The ancient innate immune system, dating back to the first multicellular organisms, utilizes phagocytic cells, soluble antimicrobial peptides, and the complement system for an immediate line of defence against pathogens. Using a limited number of germline-encoded pattern recognition receptors including the Toll-like, RIG-1-like, and NOD-like receptors, the innate immune system recognizes so-called pathogen-associated molecular patterns (PAMPs). PAMPs are specific for groups of related microorganisms and represent highly conserved, mostly non-protein molecules essential for the pathogens' life cycles. Hence, escape mutants strongly reduce the pathogen's fitness. An important task of the innate immune system is to distinguish between harmless antigens and potentially dangerous pathogens. Ideally, innate immune cells should activate the adaptive immune cells only in the case of invading pathogens. The evolutionarily rather new adaptive immune system, which can be found in jawed fish and higher vertebrates, needs several days to mount an efficient response upon its first encounter with a certain pathogen. As soon as antigen-specific lymphocyte clones have been expanded, they powerfully fight the pathogen. Importantly, memory lymphocytes can often protect us from reinfections. During the development of T and B lymphocytes, many millions of different receptors are generated by somatic recombination and hypermutation of gene segments making up the antigen receptors. This process carries the inherent risk of autoimmunity, causing most inflammatory rheumatic diseases. In contrast, inadequate activation of the innate immune system, especially activation of the inflammasomes, may cause autoinflammatory syndromes.

Innate vs acquired immunity

2013 ◽  
pp. 356-364
Author(s):  
Reinhard E. Voll ◽  
Barbara M. Bröker
Keyword(s):  
Immune System ◽  
Immune Cells ◽  
Innate Immune System ◽  
Adaptive Immune System ◽  
Innate Immune ◽  
Inflammatory Rheumatic Diseases ◽  
Antigen Receptors ◽  
Phagocytic Cells ◽  
Adaptive Immune ◽  
Adaptive Immune Cells

The innate and the adaptive immune system efficiently cooperate to protect us from infections. The ancient innate immune system, dating back to the first multicellular organisms, utilizes phagocytic cells, soluble antimicrobial peptides, and the complement system for an immediate line of defence against pathogens. Using a limited number of germline-encoded pattern recognition receptors including the Toll-like, RIG-1-like, and NOD-like receptors, the innate immune system recognizes so-called pathogen-associated molecular patterns (PAMPs). PAMPs are specific for groups of related microorganisms and represent highly conserved, mostly non-protein molecules essential for the pathogens’ life cycles. Hence, escape mutants strongly reduce the pathogen’s fitness. An important task of the innate immune system is to distinguish between harmless antigens and potentially dangerous pathogens. Ideally, innate immune cells should activate the adaptive immune cells only in the case of invading pathogens. The evolutionarily rather new adaptive immune system, which can be found in jawed fish and higher vertebrates, needs several days to mount an efficient response upon its first encounter with a certain pathogen. As soon as antigen-specific lymphocyte clones have been expanded, they powerfully fight the pathogen. Importantly, memory lymphocytes can often protect us from reinfections. During the development of T and B lymphocytes, many millions of different receptors are generated by somatic recombination and hypermutation of gene segments making up the antigen receptors. This process carries the inherent risk of autoimmunity, causing most inflammatory rheumatic diseases. In contrast, inadequate activation of the innate immune system, especially activation of the inflammasomes, may cause autoinflammatory syndromes.

scholarly journals How the Innate Immune System Fights for Your Health

2021 ◽  
Vol 9 ◽  
Author(s):  
Mieke C. Louwe ◽  
Pål Aukrust
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Innate Immune Response ◽  
Innate Immune System ◽  
The Body ◽  
Innate Immune ◽  
Response Activation

When your body encounters intruders like viruses, bacteria, fungi, or parasites, this invasion triggers a complex and amazing process called the immune response. Activation of the body’s immune system is necessary to fight off these intruders, but it must also distinguish them from the body’s own healthy tissues. The goal of the immune response is to keep the body healthy. The earliest responses that occur to protect the body from invading organisms is called the innate immune response. In this article, we explain the components of the innate immune system and how this system helps to keep the body safe from dangerous invaders.

scholarly journals Inflammasomes as Targets for Adjuvants

Pathogens ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 252 ◽  
Author(s):  
Konstantin Ivanov ◽  
Ekaterina Garanina ◽  
Albert Rizvanov ◽  
Svetlana Khaiboullina
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Infectious Diseases ◽  
Innate Immune System ◽  
Adaptive Immune System ◽  
Mechanisms Of Action ◽  
Innate Immune ◽  
Inflammasome Activation ◽  
Adaptive Immune ◽  
Pro Inflammatory Cytokines

Inflammasomes are an essential part of the innate immune system. They are necessary for the development of a healthy immune response against infectious diseases. Inflammasome activation leads to the secretion of pro-inflammatory cytokines such as IL-1β and IL-18, which stimulate the adaptive immune system. Inflammasomes activators can be used as adjuvants to provide and maintain the strength of the immune response. This review is focused on the mechanisms of action and the effects of adjuvants on inflammasomes. The therapeutic and prophylaxis significance of inflammasomes in infectious diseases is also discussed.

scholarly journals Host Innate Immunity Against Hepatitis Viruses and Viral Immune Evasion

2021 ◽  
Vol 12 ◽  
Author(s):  
Chonghui Xu ◽  
Jizheng Chen ◽  
Xinwen Chen
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Innate Immune Response ◽  
Innate Immune System ◽  
Immune Surveillance ◽  
Innate Immune ◽  
Hepatitis Viruses ◽  
Specific Pathogen ◽  
Causative Agents ◽  
Immune Sensing

Hepatitis viruses are primary causative agents of hepatitis and represent a major source of public health problems in the world. The host innate immune system forms the first line of defense against hepatitis viruses. Hepatitis viruses are sensed by specific pathogen recognition receptors (PRRs) that subsequently trigger the innate immune response and interferon (IFN) production. However, hepatitis viruses evade host immune surveillance via multiple strategies, which help compromise the innate immune response and create a favorable environment for viral replication. Therefore, this article reviews published findings regarding host innate immune sensing and response against hepatitis viruses. Furthermore, we also focus on how hepatitis viruses abrogate the antiviral effects of the host innate immune system.

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