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Innate and Adaptive Immune Dysfunction and Necrotizing Enterocolitis
Published in David J. Hackam, Necrotizing Enterocolitis, 2021
Paula Osterhout, Christina S. Kim, Erika C. Claud
Innate immunity is present at birth prior to microbial exposure while the adaptive immune system is the more specific branch of immunity, with responses tailored to specific microbial/antigen stimuli. Innate immunity for an infant begins with maternal immunoglobulins passively acquired in utero (2–4). Other physical intestinal characteristics limit microbial/host interactions. Peristalsis moves intestinal contents through the intestinal tract to limit bacterial adherence, while secretion of gastric acid decreases intestinal pH to limit bacterial growth. For organisms that persist in the intestine, the intestinal mucosal barrier limits contact with the epithelium, while enterocyte inflammatory responses and phagocytic cell responses limit microbial proliferation.
Specificity and Neutralizing Properties of Cross-Reactive Anti-Core LPS Monoclonal Antibodies
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Franco E. Di Padova, Didier Heumann, Michel Pierre Glauser, Ernst T. Rietschel
As these models are dependent on the administration of purified LPS, it was relevant to analyze additional models in which LPS toxic effects are not caused through a direct administration of the purified endotoxin. Gut ischemia induces disruption of the intestinal mucosal barrier, allowing translocation of bacteria and endotoxin into the blood, which may trigger a systemic inflammatory response, lung injury, and lethality. It was, therefore, evaluated whether WN1 222α5 reduces the mortality rate in rats and protects from the lung injury following ischemia reperfusion injury to the gut (56). From this study it appears that WN1 22215 is protective, and this finding clearly suggests that endotoxin derived from enteric bacteria might play an important role in the pathogenesis of lung injury. Moreover, WN1 222–5 almost completely neutralized the plasma endotoxin concentrations observed in control animals. Similar conclusions have been reached by showing that selective gut decontamination can reduce the generation of LPS, TNF, and the severity of lung damage that often follows ischemia and reperfusion of the intestine in rats (57).
Probiotics in the Management of Inflammatory Bowel Disease and Irritable Bowel Syndrome
Published in Marcela Albuquerque Cavalcanti de Albuquerque, Alejandra de Moreno de LeBlanc, Jean Guy LeBlanc, Raquel Bedani, Lactic Acid Bacteria, 2020
Larissa S Celiberto, Bruce A Vallance, Daniela CU Cavallini
Over the last several decades, the use of beneficial microbes known as probiotics have been seen as a potential strategy to favorably modulate the intestinal microbiota to promote health and treat microbial dysbiosis-related diseases. Probiotics are defined by the WHO as live microorganisms that confer a health benefit to the host when administered in adequate amounts (FAO/WHO 2002, Hill et al. 2014), and these beneficial microbes may positively influence microbial interactions with the immune system and the gut epithelium (DuPont and DuPont 2011). Several microorganisms classified as probiotics belong to the lactic acid bacteria (LAB) group (e.g., Lactobacillus spp., Lactococcus spp., Enterococcus spp.). LAB produce lactic acid as their major end product of carbohydrate fermentation. Moreover, besides having microbicidal activity against enteric pathogens, some LAB strains compete for cell surface and mucin binding sites, thus offering protection to the host by strengthening the intestinal mucosal barrier (Ljungh and Wadström 2006). Additionally, lactic acid also contributes to the sensory and texture profile of food products, making this group of bacteria highly investigated as potential probiotics.
Sestrin2 suppresses ferroptosis to alleviate septic intestinal inflammation and barrier dysfunction
Published in Immunopharmacology and Immunotoxicology, 2023
Wei Liu, Chanchan Xu, Zhiqiang Zou, Qinyong Weng, Ying Xiao
Under normal circumstances, there is a dynamic balance between the intestinal flora and its products and the intestinal mucosal barrier [29]. The intestinal mucosal barrier can prevent the loss of water and electrolytes, prevent antigens, microorganisms and other harmful substances from entering the body. In addition, it enables the human body to exchange molecular with the environment [30]. Whereas, in sepsis, increased oxidative stress, followed by an overproduction of ROS, disrupts mitochondrial integrity and leads to disturbances in energy metabolism [31]. Therefore, an intact intestinal mucosal barrier plays a vital role in maintaining the regular function of the body and preventing intestinal diseases. LPS is a unique component in the cell wall of Gram-negative bacteria that is released into the gut environment following bacterial death and lysis. After high concentrations of LPS enter the blood circulation, it will disturb the host’s immune system and cause sepsis [32]. Herein, SESN2 was significantly down-regulated in patients with septic intestinal dysfunction, and the level of SESN2 was also found to be down-regulated in LPS-treated Caco-2 cells. This is the first time that SESN2 has been defined to have decreased levels in human septic intestinal dysfunction. SESN2 may be regarded as a potential indicator for clinical monitoring of the progression of septic intestinal injury.
Probiotics Improve Postoperative Adaptive Immunity in Colorectal Cancer Patients: A Systematic Review and Meta-Analysis
Published in Nutrition and Cancer, 2022
Jie Chen, Huamin Liang, Jiaying Lu, Yanping He, Renxu Lai
The intestinal mucosal barrier possesses physical, biochemical, and immune properties. In addition, having a large number of microbiota is of great importance to barrier function because of the interaction between the host and gut microorganisms (16). Complete barrier mucosal function can effectively prevent bacteria, toxins, and other harmful substances from entering the bloodstream. For patients undergoing resection for colorectal cancer, the intestinal mucosal barrier suffers different degrees of damage because of impaired epithelial cells, disturbance of the intestinal flora, bowel preparation, use of antibiotics and surgical trauma. Therefore, these patients are prone to develop intestinal flora disorders, enterogenous infections, endotoxins, immune disorders, etc. Clinicians can solve these problems in two ways: restore the integrity of the intestinal mucosal barrier and enhance the body’s immunity.
Temporal and region-specific effects of sleep fragmentation on gut microbiota and intestinal morphology in Sprague Dawley rats
Published in Gut Microbes, 2020
Judy Triplett, David Ellis, Amber Braddock, Erin Roberts, Katherine Ingram, Eric Perez, Amanda Short, Dominique Brown, Victoria Hutzley, Chelsey Webb, Armando Soto, Victor Chan
The intestinal mucosal barrier functions to contain undesirable luminal contents within the intestinal tracts to prevent uncontrolled translocation of luminal contents through the intestine into the body, protecting mucosal tissues and the circulatory system from exposure to pathogenic microorganisms, pro-inflammatory molecules and toxins.58 Previously, it has been shown that sleep deprivation in rats promoted extraintestinal microbial invasion of anaerobic microbes in the mesenteric lymph nodes, liver and spleen after 5 days without sleep.59 In these current SF studies, we found a similar increased presence of bacteria in the spleen following acute SF. No significant microbial invasions were noted in any other tissue tested. The acute SF data showed varying degrees of increased microbial invasion (as well as microbial adhesion and penetration), but a large standard deviation made these changes not statistically significant. The result of chronic SF was somewhat unexpected as microbial adhesion and penetration were decreased in both the distal ileum and in the cecum. In addition, no microbial invasion of surround tissues was observed with chronic SF. It is possible that microbial invasion may have increased in other organs that were not studied; however, the results from the LBP and occludin assays suggest that the gut does not becomes leaky after SF under the SF condition employed in this study.