The role of macrophages in inflammatory bowel diseases

Author(s):  
Sigrid E.M. Heinsbroek ◽  
Siamon Gordon

The small and large intestine contain the largest number of macrophages in the body and these cells are strategically located directly underneath the epithelial layer, enabling them to sample the lumen. Such intestinal macrophages have a different phenotype from other tissue macrophages in that they ingest and may kill microbes but they do not mediate strong pro-inflammatory responses upon microbial recognition. These properties are essential for maintaining a healthy intestine. It is generally accepted that tolerance to the intestinal flora is lost in inflammatory bowel diseases, and genes involved in microbial recognition, killing and macrophage activation have already been associated with these diseases. In this review, we shed light on the intestinal macrophage and how it influences intestinal immunity.

2015 ◽  
Vol 53 (2) ◽  
pp. 118-127 ◽  
Author(s):  
Al.C. Moldoveanu ◽  
M. Diculescu ◽  
Carmen Fierbinţeanu Braticevici

Abstract Inflammatory bowel diseases are chronic afflictions, characterized by active and remission periods. Inflammation is the most common type of response that the human body uses as a defense mechanism against aggressors from the environment. The frequency and degree of inflammation depends on the size of the affected tissues. The gastrointestinal tract is, by far, the most susceptible tissue to inflammatory responses, because of its constant exposure to various antigenic, mutagenic and toxic factors. In inflammatory bowel diseases there is a loss of immune tolerance to intestinal flora that is mediated by various substances, including cytokines. Cytokines represent a key signal in the intestinal immune response. Activated dendritic cells and macrophages secrete cytokines that actively intervene in inflammation regulation, in both Crohn’s disease and ulcerative colitis. After their secretion by antigen presented cells, cytokines activate and differentiate T cells, stirring up the adaptive immune response. Cytokines have an important role in the pathogenesis of inflammatory bowel diseases. The identification of new cytokines, as well as the changing of the pathogenesis paradigms in inflammatory bowel diseases has been done on animal tests and clinical studies. Thus, there is promising evidence basis for future therapy research based on cytokines, and anti-cytokine antibodies.


2021 ◽  
Vol 9 (4) ◽  
pp. 697
Author(s):  
Valerio Baldelli ◽  
Franco Scaldaferri ◽  
Lorenza Putignani ◽  
Federica Del Chierico

Inflammatory bowel diseases (IBDs) are a group of chronic gastrointestinal inflammatory diseases with unknown etiology. There is a combination of well documented factors in their pathogenesis, including intestinal microbiota dysbiosis. The symbiotic microbiota plays important functions in the host, and the loss of beneficial microbes could favor the expansion of microbial pathobionts. In particular, the bloom of potentially harmful Proteobacteria, especially Enterobacteriaceae, has been described as enhancing the inflammatory response, as observed in IBDs. Herein, we seek to investigate the contribution of Enterobacteriaceae to IBD pathogenesis whilst considering the continuous expansion of the literature and data. Despite the mechanism of their expansion still remaining unclear, their expansion could be correlated with the increase in nitrate and oxygen levels in the inflamed gut and with the bile acid dysmetabolism described in IBD patients. Furthermore, in several Enterobacteriaceae studies conducted at a species level, it has been suggested that some adherent-invasive Escherichia coli (AIEC) play an important role in IBD pathogenesis. Overall, this review highlights the pivotal role played by Enterobacteriaceae in gut dysbiosis associated with IBD pathogenesis and progression.


2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Marina García-Miguel ◽  
M. Julieta González ◽  
Rodrigo Quera ◽  
Marcela A. Hermoso

Innate immunity prevents pathogens from entering and spreading within the body. This function is especially important in the gastrointestinal tract and skin, as these organs have a large surface contact area with the outside environment. In the intestine, luminal commensal bacteria are necessary for adequate food digestion and play a crucial role in tolerance to benign antigens. Immune system damage can create an intestinal inflammatory response, leading to chronic disease including inflammatory bowel diseases (IBD). Ulcerative colitis (UC) is an IBD of unknown etiology with increasing worldwide prevalence. In the intestinal mucosa of UC patients, there is an imbalance in the IL-33/ST2 axis, an important modulator of the innate immune response. This paper reviews the role of the IL-33/ST2 system in innate immunity of the intestinal mucosa and its importance in inflammatory bowel diseases, especially ulcerative colitis.


Nutrients ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 3402
Author(s):  
Barbara Borsani ◽  
Raffaella De Santis ◽  
Veronica Perico ◽  
Francesca Penagini ◽  
Erica Pendezza ◽  
...  

Carrageenan (CGN) is a high molecular weight polysaccharide extracted from red seaweeds, composed of D-galactose residues linked in β-1,4 and α-1,3 galactose-galactose bond, widely used as a food additive in processed foods for its properties as a thickener, gelling agent, emulsifier, and stabilizer. In recent years, with the spread of the Western diet (WD), its consumption has increased. Nonetheless, there is a debate on its safety. CGN is extensively used as an inflammatory and adjuvant agent in vitro and in animal experimental models for the investigation of immune processes or to assess the activity of anti-inflammatory drugs. CGN can activate the innate immune pathways of inflammation, alter the gut microbiota composition and the thickness of the mucus barrier. Clinical evidence suggests that CGN is involved in the pathogenesis and clinical management of inflammatory bowel diseases (IBD), indeed food-exclusion diets can be an effective therapy for disease remission. Moreover, specific IgE to the oligosaccharide α-Gal has been associated with allergic reactions commonly referred to as the “α-Gal syndrome”. This review aims to discuss the role of carrageenan in inflammatory bowel diseases and allergic reactions following the current evidence. Furthermore, as no definitive data are available on the safety and the effects of CGN, we suggest gaps to be filled and advise to limit the human exposure to CGN by reducing the consumption of ultra-processed foods.


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