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.
The Roles of the Human Placenta in Fetal-Maternal Tolerance
Ornella Parolini, Antonietta Silini in Placenta, 2016
Traditionally, the immune system is divided into two systems: innate immunity and adaptive immunity (Abbas et al. 2007). The innate immune system provides the first line of defense against pathogens and works mainly through leukocyte recognition of common pathogen structures. All cellular components of the innate immune system are able to recognize microbial structures by specialized pattern recognition receptors (Akira et al. 2006; Akira and Takeda 2004). Adaptive immunity enables adaptation to an infection and increases in magnitude with each successive exposure to a specific microbe (Abbas et al. 2007). The main players of the adaptive immune system are subsets of lymphocytes called T cells and B cells. B cells produce antibodies after maturation (LeBien and Tedder 2008) and differentiate into plasma cells or memory B cells. T cells can be classified into helper T cells (CD4+) and cytotoxic T cells (CD8+).
Immunoglobulin E: Pathogenic Relevance in Urticaria and Eczema
Ana M. Giménez-Arnau, Howard I. Maibach in Contact Urticaria Syndrome, 2014
The innate immune system is characterized as generating a quick response after its encounter with the pathogen (antigen or allergen), whereas the adaptive immune system has a specialized response, amplifying it after repeated exposures to the same pathogen. During development, T-cell lymphocyte maturation is mediated by cytokines and cell–cell interaction. There are two important types of T-cell lymphocytes regarding cell-surface markers: 1) CD4+, also called helper T cells (Th) (60%–70%) and 2) CD8+, also called suppressor T cells (30%–40%). Depending on the type of cytokine produced, Th cells differentiate into type 1 (Th1), type 2 (Th2), and the newly identified subsets, Th17 and Th22.[1,2] Whereas interleukins (IL) 4 and 13 are cytokines that induce a Th2 balance, IL-2 and interferon-γ (IFN-γ) induce Th1 environment. Th2 cells stimulate immunoglobulin (Ig) E production by B cells. The balance of these stimulatory and inhibitory activities of the Th1 and Th2 is believed to determine an individual’s propensity to develop allergic disorders or atopy. The predominance of Th1 or Th2 response in each individual has been demonstrated to be influenced by environmental factors as well as by genetic predisposition by particular population.[3] In fact, children from allergic parents are more susceptible to develop allergic disorders.[4,5] On the other hand, Th17 and Th22 cells have been described in the context of asthma, where the neutrophil is predominant in the infiltrate, and in non-IgE-related atopic eczema as well as in chronic phases of atopic eczema.[2,6]
The interaction between innate immunity and oral microbiota in oral diseases
Published in Expert Review of Clinical Immunology, 2023
Hongzhi He, Yu Hao, Yu Fan, Bolei Li, Lei Cheng
First, the impact of innate immune cells on oral microbiota and its mechanisms are still needed to be investigated. Innate immune cells constitute a crucial part of innate immunity. Previous studies mainly focus on how innate immune cells interact with certain kinds of microorganisms. However, the current understanding of the effects of innate immune cells on oral microbiota is still very limited. The oral microbiota is formed by a collection of compositionally distinct microbial communities. Microorganisms within oral microbiota interact with each other and exert a complex and synergistic effect in response to the host immune system [11]. Thus, it is necessary to investigate the modulation of innate immune cells on the composition of oral microbial communities and their specific mechanisms.
Critical influence of cytokines and immune cells in autoimmune gastritis
Published in Autoimmunity, 2023
Zepeng Zhang, Tongtong Zhu, Lei Zhang, Yanchao Xing, Zhiqiang Yan, Qingsong Li
Human immune system consists of innate immunity and adaptive immunity. Innate immunity is also known as non-specific immunity. Innate immunity involves some innate immune cells (macrophages, DCs, NK cells) that quickly respond to foreign microorganisms entering the human body. It is a natural initial line of defense that prevents viruses, microorganisms, or tissue damage. Adaptive immunity is also called specific immunity, which generally occurs after innate immunity. Adaptive immunity generally refers to a series of immune responses mediated by T cells and B cells [17]. However, the immune system plays a dual role in the progression of AIG. On the one hand, innate immunity and acquired immunity defend against inflammatory substances and maintain the stability of the body. On the other hand, immune cells and cytokines continue to accumulate in the immune environment of the stomach, and a large number of recruited immune cells participate in suppressing the immune microenvironment, promoting inflammatory progression and leading to immune escape of tumour cells [18]. Once the benign immune response process is out of balance, it is easy to provoke immune diseases.
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].
Related Knowledge Centers
- Adaptive Immune System
- Antigen Presentation
- Bacteria
- Coagulation
- Immune Complex
- Lymph
- Multicellular Organism
- White Blood Cell
- Cytokine
- Complement System