Functions of Macrophages in the Maintenance of Intestinal Homeostasis
TL;DR: Understanding the mechanisms employed by intestine macrophages in mediating intestinal immune homeostasis and inflammation, as well as the mode of action of dietary nutrients in the modulating functions of intestinal macrophage, represents an opportunity to prevent and control inflammatory bowel diseases.
Abstract: Intestinal macrophages constitute the largest pool of macrophages in the body and have emerged as crucial sentinels for pathogen recognition and elimination. The source and development of intestinal macrophages, as well as their distinct properties have been well documented. Intestinal macrophages exert their functions in the maintenance of intestinal homeostasis by shaping host-microbiota symbiosis, managing gut inflammation, crosstalking with T cells, and facilitating wound repair. Recently, nutritional regulation of intestinal macrophages has attracted substantial attention and is becoming a promising approach to disease prevention and control. Understanding the mechanisms employed by intestinal macrophages in mediating intestinal immune homeostasis and inflammation, as well as the mode of action of dietary nutrients in the modulating functions of intestinal macrophages, represents an opportunity to prevent and control inflammatory bowel diseases.
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13 Feb 2020
TL;DR: Overexpression of proinflammatory cytokines with subsequent reduction of anti-inflammatory markers in obesity, is considered to be the link between obesity-induced inflammation and endothelial dysfunction.
Abstract: Obesity is characterized by the excessive deposition of fat that may interfere with the normal metabolic process of the body. It is a chronic condition associated with various metabolic syndromes, whose prevalence is grossly increasing, and affects both children and adults. Accumulation of excessive macronutrients on the adipose tissues promotes the secretion and release of inflammatory mediators, including interleukin-6 (IL-6), interleukin 1β, tumor necrotic factor-α (TNF-α), leptin, and stimulation of monocyte chemoattractant protein-1 (MCP-1), which subsequently reduce the production of adiponectin thereby initiating a proinflammatory state. During obesity, adipose tissue synthesizes and releases a large number of hormones and cytokines that alter the metabolic processes, with a profound influence on endothelial dysfunction, a situation associated with the formation of atherosclerotic plaque. Endothelial cells respond to inflammation and stimulation of MCP-1, which is described as the activation of adhesion molecules leading to proliferation and transmigration of leukocytes, which facilitates their increase in atherogenic and thromboembolic potentials. Endothelial dysfunction forms the cornerstone of this discussion, as it has been considered as the initiator in the progression of cardiovascular diseases in obesity. Overexpression of proinflammatory cytokines with subsequent reduction of anti-inflammatory markers in obesity, is considered to be the link between obesity-induced inflammation and endothelial dysfunction. Inhibition of inflammatory mechanisms and management and control of obesity can assist in reducing the risks associated with cardiovascular complications.
141 citations
TL;DR: The importance of vitamin D/VDR signaling in intestinal homeostasis is evidenced by the development of a chronic inflammatory state (e.g. IBD) when this signaling system is disrupted.
95 citations
TL;DR: Understanding the interplay between functional and immunological responses inside animal or human gut as influenced by pectin in diets is provided, and this knowledge can be used to define preferred dietary pectins, targeting beneficial bacteria, and favoring balanced microbiota communities in the gut to maximize pECTins' health benefits.
57 citations
Journal Article•
TL;DR: In this article, the authors use several mouse models to show that Treg cells, after their generation in lymph nodes, need to home to the gut to undergo local expansion to install oral tolerance.
Abstract: Tolerance to food antigen manifests in the absence and/or suppression of antigen-specific immune responses locally in the gut but also systemically, a phenomenon known as oral tolerance. Oral tolerance is thought to originate in the gut-draining lymph nodes, which support the generation of FoxP3(+) regulatory T (Treg) cells. Here we use several mouse models to show that Treg cells, after their generation in lymph nodes, need to home to the gut to undergo local expansion to install oral tolerance. Proliferation of Treg cells in the intestine and production of interleukin-10 by gut-resident macrophages was blunted in mice deficient in the chemokine (C-X3-C motif) receptor 1 (CX3CR1). We propose a model of stepwise oral tolerance induction comprising the generation of Treg cells in the gut-draining lymph nodes, followed by migration into the gut and subsequent expansion of Treg cells driven by intestinal macrophages.
37 citations
TL;DR: Higher fluoride exposure can significantly damage the intestinal structure and gut microbial composition in ducks, with an impaired structure with reduced relative distribution of goblet cells in the fluoride exposed group.
26 citations
References
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TL;DR: This Review suggests a new grouping of macrophages based on three different homeostatic activities — host defence, wound healing and immune regulation, and proposes that similarly to primary colours, these three basic macrophage populations can blend into various other 'shades' of activation.
Abstract: Macrophages display remarkable plasticity and can change their physiology in response to environmental cues. These changes can give rise to different populations of cells with distinct functions. In this Review we suggest a new grouping of macrophage populations based on three different homeostatic activities - host defence, wound healing and immune regulation. We propose that similarly to primary colours, these three basic macrophage populations can blend into various other 'shades' of activation. We characterize each population and provide examples of macrophages from specific disease states that have the characteristics of one or more of these populations.
7,384 citations
TL;DR: Recently, substantial advances in the understanding of the molecular pathogenesis of inflammatory bowel disease (IBD) have been made owing to three related lines of investigation as mentioned in this paper, which have shown the importance of epithelial barrier function, and innate and adaptive immunity in disease pathogenesis.
Abstract: Recently, substantial advances in the understanding of the molecular pathogenesis of inflammatory bowel disease (IBD) have been made owing to three related lines of investigation. First, IBD has been found to be the most tractable of complex disorders for discovering susceptibility genes, and these have shown the importance of epithelial barrier function, and innate and adaptive immunity in disease pathogenesis. Second, efforts directed towards the identification of environmental factors implicate commensal bacteria (or their products), rather than conventional pathogens, as drivers of dysregulated immunity and IBD. Third, murine models, which exhibit many of the features of ulcerative colitis and seem to be bacteria-driven, have helped unravel the pathogenesis/mucosal immunopathology of IBD.
3,831 citations
TL;DR: Using a murine adoptive transfer system to probe monocyte homing and differentiation in vivo, two functional subsets among murine blood monocytes are identified: a short-lived CX(3)CR1(lo)CCR2(+)Gr1(+) subset that is actively recruited to inflamed tissues and a CX (3) CR1(hi)CCS1-dependent recruitment to noninflamed tissues.
3,307 citations
TL;DR: Understanding the specific molecular events that regulate the production of IL-10 will help to answer the remaining questions that are important for the design of new strategies of immune intervention.
Abstract: Interleukin-10 (IL-10), a cytokine with anti-inflammatory properties, has a central role in infection by limiting the immune response to pathogens and thereby preventing damage to the host. Recently, an increasing interest in how IL10 expression is regulated in different immune cells has revealed some of the molecular mechanisms involved at the levels of signal transduction, epigenetics, transcription factor binding and gene activation. Understanding the specific molecular events that regulate the production of IL-10 will help to answer the remaining questions that are important for the design of new strategies of immune intervention.
2,491 citations
TL;DR: The mechanisms that control monocyte trafficking under homeostatic, infectious and inflammatory conditions are being unravelled and are the focus of this Review.
Abstract: Monocytes originate from progenitors in the bone marrow and traffic via the bloodstream to peripheral tissues. During both homeostasis and inflammation, circulating monocytes leave the bloodstream and migrate into tissues where, following conditioning by local growth factors, pro-inflammatory cytokines and microbial products, they differentiate into macrophage or dendritic cell populations. Recruitment of monocytes is essential for effective control and clearance of viral, bacterial, fungal and protozoal infections, but recruited monocytes also contribute to the pathogenesis of inflammatory and degenerative diseases. The mechanisms that control monocyte trafficking under homeostatic, infectious and inflammatory conditions are being unravelled and are the focus of this Review.
2,309 citations