Giardia lamblia
Dongyou Liu in Laboratory Models for Foodborne Infections, 2017
The innate immune system serves as an early line of defense against pathogens as it does not require the specificity of adaptive immunity to exert its protective effects. The importance of innate immunity in the control of G. lamblia infection is not well characterized. However, several studies have shown that innate immune effectors do have a role in G. lamblia infection. Antimicrobial peptides like defensins and lactoferrin have been shown to kill G. lamblia in vitro.96,97 Another potent antimicrobial, nitric oxide (NO), has also been shown to have inhibitory effects on G. lamblia growth and survival in an in vitro model using human intestinal epithelia cells.98 Studies in G. lamblia-infected mice have shown that while NO produced by inducible NO synthase (NOS2) may not be effective in controlling infection alone, it may have a redundant role with MMP-7, a protease required for cleavage of defensins.85,99 These studies demonstrated that while a loss of either NOS2 or MMP-7 did not affect infection clearance, mice lacking both MMP-7 and NOS2 had a defect in parasite clearance.
Immune system of the newborn
Prem Puri in Newborn Surgery, 2017
The first line of defense against infection is the innate immune system, and activation occurs when a pathogen breaches the host’s natural barriers (Figure 19.1).1 The innate immune system developed before the separation of vertebrates from invertebrates and is the primary immune response for most multicellular organisms.2 It responds instantaneously to microbes and is composed of both soluble (the alternative and mannan-binding lectin pathways of the complement system, acute phase proteins, and cytokines) and cellular elements (monocytes, macrophages, neutrophils, dendritic cells, and natural killer cells). Careful modulation of the innate immune system is vital to prevent either uncontrolled microbial growth or devastating inflammatory responses with tissue injury, vascular collapse, and multiorgan failure. Neonatal immunological research has concentrated on umbilical cord blood, and there is a paucity of detailed mechanistic research in neonatal postnatal samples due to the smaller blood volumes available. Recent developments in the analysis of microsamples including microarrays and multiplex assays have allowed rapid advances in the understanding of neonatal immunology during early development.
Immunology
Anthony R. Mundy, John M. Fitzpatrick, David E. Neal, Nicholas J. R. George in The Scientific Basis of Urology, 2010
Nonspecific barriers to infection are the first obstacles a pathogen must overcome to achieve successful invasion of its host. These barriers are not acquired, do not change, and allow the specific immune system time to mount a response. The innate system of immune defense is, therefore, fast-acting but relatively nonspecific and nonadaptive. However, it is increasingly clear that the type of innate response influences the quality and quantity of the subsequent specific immune response. At the simplest level, the innate immune system consists of physical and biochemical barriers such as the skin, mucus, acid in the stomach, and lysozyme in many secretions, which all help to prevent the entry of microorganisms into the body. In addition, a battery of complex mechanisms designed to eliminate microbes that have penetrated normal body tissues also exists. More recently, the receptors by which danger is sensed by the innate immune system have been described. C-type lectin receptors (CLRs)Toll-like receptors (TLRs)Nod-like receptors (NLRs)Retinoid acid–inducible gene-1 (Rig-1)-like receptors (RLRs)
Delivery of toll-like receptor agonists by complement C3-targeted liposomes activates immune cells and reduces tumour growth
Published in Journal of Drug Targeting, 2021
Alexandra Francian, Ashley Widmer, Troy Olsson, Marisabel Ramirez, Darion Heald, Keaton Rasic, Luke Adams, Holly Martinson, Max Kullberg
The innate immune system is the first line of defense against pathogens and results in an immediate but non-specific immune response. Antigen presenting cells (APCs) are critical for the establishment of an innate immune response against bacteria, viruses, and cancer, and play a crucial role in the initiation, regulation and the subsequent direction of an adaptive immune response. APCs include cell types of myeloid lineage (monocytes, macrophages, and dendritic cells), as well as lymphoid B cells [1–3]. Due to the gatekeeping role of APCs in regulating how the immune system responds to an infection or to cancer, there are several therapies that aim to exploit their function, such as ex vivo antigen-loading, expansion of immunostimulatory dendritic cells (DCs), nanoparticle vaccines, and artificial APCs [4–6].
COVID-19 Infection: Concise Review Based on the Immunological Perspective
Published in Immunological Investigations, 2022
Parisa Lotfinejad, Zahra Asadzadeh, Shiva Najjary, Mohammad Hossein Somi, Khalil Hajiasgharzadeh, Ahad Mokhtarzadeh, Afshin Derakhshani, Elmira Roshani, Behzad Baradaran
The immune response has a significant role in several steps of infection and disease. The initial and most vital step in a host’s response to viral infection is the detection of the viral factor through the immune system. Recognition of viral infection stimulates the generation of antiviral proteins, the expansion of cytokines, and the recruitment of immune cells to the infection site. The innate immune system is the first step of protection against pathogens. It extends several strategies to detect invading viruses, and next signaling pathways are targeted at the primary inhibition of infection (Woodland 2018). Although the SARS-CoV and MERS-CoV outbreak in last years resulted in a global epidemic, the more recently detected severe acute respiratory syndrome, COVID-19 leads to an extreme case-fatality rate and can cause severe respiratory disease (Xia et al. 2020). According to their genetic plasticity, SARS-CoV and MERS-CoV have expanded numerous mechanisms to avoid the innate immune response. Formerly several molecular strategies of innate immune evasion by +ssRNA viruses have been described (Nelemans and Kikkert 2019). According to achieved information about SARS-CoV and MERS-CoV, collected clinical and experimental evidence on these viruses, and their genomic similarity with SARS-CoV-2, we can assume and even anticipate how SARS-CoV-2 can be detected by the host immune system and how this virus can evade from the immune responses (Prompetchara et al. 2020). In this part, we will focus on the immune evasion of this virus using experience gained from the outbreak of SARS-CoV and MERS-CoV.
IL-23 inhibition for the treatment of psoriatic arthritis
Published in Expert Opinion on Biological Therapy, 2022
Raagav Mohanakrishnan, Secia Beier, Atul Deodhar
PsA is an immune mediated disease leading to synovial membrane and entheseal inflammation, characterized by increased vascularization and innate and adaptive immune cell infiltration [14]. The innate immune system consists of physical surfaces (skin, mucous membranes) on the human body that serve as barriers to organisms such as bacteria and viruses. It also consists of immune system cells such as neutrophils and natural killer cells that provide nonspecific defense to foreign organisms [15]. In contrast, the adaptive immune system consists of T and B lymphocytes that provide more targeted defense against organisms [15]. T cells have the ability to activate various other mechanisms within the immune system, including B cells which are able to become plasma cells and form antibodies. More specifically, T cells are divided into T helper cells, and cytotoxic T cells; and T helper cells further specialize into Th1, Th2, Th17, and T-Reg cells. T helper cells release multiple cytokines (gamma interferon, tumor necrosis factor alfa, IL-17 etc.), that are then able to activate various parts of the immune system [15]. These cytokines are major players in the human immune system and have also been implicated in immune-mediated processes such as PsA.
Related Knowledge Centers
- Adaptive Immune System
- Antigen Presentation
- Bacteria
- Coagulation
- Immune Complex
- Lymph
- Multicellular Organism
- White Blood Cell
- Complement System
- Cytokine