and integrins have been shown to modulate numerous cell functions such as viability, proliferation. The integrin family of cell-surface receptors is the primary receptor responsible for mediating adhesion to extracellular matrix proteins ( Hynes, 2002). Interestingly, many of these receptors also direct intracellular signaling, adhesion, motility, and maturation of DCs. Notably, DC endocytic and phagocytic receptors for antigen uptake include C-type lectins (DEC205, CD206),Toll-like receptors (TLR4), Fcγ receptors, and integrins (αVβ5, CD11c) ( Akira et al., 2006 Takeda et al., 2003 Lundberg et al., 2014). They are equipped with a wide array of endocytic and phagocytic surface receptors that recognize a host of molecules including proteins, lipids, sugars, glycoproteins, glycolipids, and oligonucleotides ( Lewis et al., 2014). The mechanisms involved in this environmental sampling include (i) fluid-phase macropinocytosis, (ii) receptor-mediated endocytosis, and (iii) phagocytosis for larger particulate foreign bodies ( Fadilah and Cheong, 2007). They circulate throughout the peripheral blood and tissues and are able to “scavenge” pathogens, foreign materials, and apoptotic or necrotic cells ( Banchereau et al., 2000). Immature DCs (iDCs) function as the body’s sentinels. Keselowsky, in Host Response to Biomaterials, 2015 DC receptors and adhesion to extracellular matrix proteins Further studies will reveal the relevance of various dendritic cell populations in host defense and lung pathology. Most of this work has been done in the murine models, although studies to define dendritic cell subsets in humans are being conducted. Recent studies have provided evidence for an increasing number of lung dendritic cell subsets identified and defined by their cell surface markers, cytokines produced, and functional attributes. Thus, T H1 responses eliminate intracellular microorganisms, T H2 responses eliminate parasites, and T H17 responses eliminate conventional bacterial threats. Each subset is thought to be optimized for specific microbial challenges.
These subsets are defined by cell surface markers, transcription factors expressed, and cytokines produced. A number of T helper (T H) subsets have been described, including T H1, T H2, and T H17 and regulatory T cells. When a naive T lymphocyte recognizes an antigen-presenting dendritic cell with the requisite costimulatory signals, T lymphocyte differentiation usually occurs. These antigens are then “presented” to cells of the adaptive immune system (primarily lymphocytes). Activated dendritic cells then travel to local lymph nodes with processed antigen on their cell surface. Dendritic cells bind, internalize, and process antigens and then display them on their surface in the cleft of major histocompatibility complex (MHC I) or MHC II molecules. These cells, resident within tissues, develop in vivo from hematopoietic precursor cells. Downey, in Clinical Respiratory Medicine (Fourth Edition), 2012 Dendritic Cellsĭendritic cells function as “conductors” of the immune response. 51 Thus treatment of established micronutrient deficiency in enteropathy or other inflammatory states may be clinically important. In particular, vitamins A and D and zinc are essential factors in the ability of intestinal dendritic cells to induce regulatory T cells 45-47 and IgA responses.
#Dendrite functions pro#
The consequences will be an appropriate pro inflammatory response and the generation of effector and memory T cells, polarized toward appropriate immune responses upon future challenge.Īs mentioned previously, micronutrient status is particularly important in dendritic cell function, and thus the establishment and maintenance of immune tolerance. The response of epithelial cells to pathogen-induced damage includes expression of both chemokines such as IL-8 and MIP-3α, which induce cell recruitment, and cytokines such as IL-1, IL-15, and TNF-α, which may activate or prime locally recruited cells. This response may follow recruitment of new dendritic cells and macrophages, which have not undergone local conditioning.
This would be quite inappropriate in the case of pathogens, which require prompt responses from the mucosal immune system.
Simon Murch, in Pediatric Gastrointestinal and Liver Disease (Sixth Edition), 2021 Dendritic Cells and Effector Immune Responses to Pathogensĭendritic cell function clearly cannot be restricted to the induction of tolerance in all circumstances.
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