Beneficial Lactic Acid Bacteria
K. Balamurugan, U. Prithika in Pocket Guide to Bacterial Infections, 2019
Positive effect of LAB can be expressed via direct action on the organism, like enhancement of barrier function. The intestinal epithelium acts as a selectively permeable barrier regulating the absorption of nutrients, electrolytes and water, and providing effective defense against toxins, antigens, and enteric flora (Groschwitz and Hogan 2009). Breakdown of intestinal barrier function plays a crucial role in development of such pathologies as infectious enteritis and inflammatory bowel diseases (Halpern and Denning 2015). Mucins, large complex glycoproteins, protect intestinal mucosal surfaces by limiting access of environmental matter to their epithelial cells. It was shown that Lactobacillus strains increased extracellular secretion of mucin, leading to reduced adherence of enteropathogen E. coli during coincubation experiments (Mack et al. 2003). The increase in intestinal permeability induced translocation of antigens across the epithelium, provoking inflammation. Bifidobacterium strains possess the capacity to prevent disruption of intestinal epithelial barrier and to promote its integrity. The up-regulation of the production of SCFA (acetate and formate) restores the barrier (Hsieh et al. 2015).
Secreted effectors of the innate mucosal barrier
Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald in Principles of Mucosal Immunology, 2020
The small intestinal epithelium absorbs nutrients, regulates water and electrolytes, and helps prevent most luminal microbes from becoming significant populations. To facilitate nutrient absorption in the small intestine, mammals maximized absorptive membrane surface area by evolving villi and an apical brush border. However, the lumen from which nutrients are absorbed is also colonized by a resident microflora and transiently exposed to microbes and foreign antigens from the diet. Although the large absorptive area of the small intestine appears to favor mucosal colonization by microorganisms, few bacteria populate the small intestine relative to populations in the cecum and colon, suggesting that the small intestine has mechanisms that counter microbial colonization of the epithelium.
Nanocarrier Technologies for Enhancing the Solubility and Dissolution Rate of Api
Debarshi Kar Mahapatra, Sanjay Kumar Bharti in Medicinal Chemistry with Pharmaceutical Product Development, 2019
Before selecting the effective carrier system for drug, one should consider the important factors regarding API and oral route of administration: A molecular mass should not be greater than 500 Daltons;An octanol-to-water partition coefficient (log P) value should not be greater than 5;pH of the GI tract: there is a significant change in pH according to location, pH of 1.2 in the empty stomach, 5–7 in the small intestine and 6 to 7.5 in the colon.The physical barriers of intestinal epithelium which consists of absorptive cells (enterocytes), secretory cells (goblet cells and paneth cells) and M cells of Peyer’s patches. The physical integrity of these intestinal epithelial cells is exhibited by tight junctions between the contiguous epithelial cells.
The role of microbiota in allogeneic hematopoietic stem cell transplantation
Published in Expert Opinion on Biological Therapy, 2021
Chia-Chi Chang, Eiko Hayase, Robert R. Jenq
Host–microbe interactions occur at mucosal surfaces, and the microbial communities at different human body sites are known to be compositionally distinct [19]. One of the largest is the human intestinal mucosa, estimated to be between 250 and 400 m2, home to between 1013 to 1014 microbes [4,20]. The intestinal epithelium is a single layer of cells comprised of intestinal epithelial cells (IECs), which includes specialized cells such as Paneth cells, goblet cells, and intestinal stem cells. IECs provide two major functions: (1) serving as a protective barrier separating the intestinal lining from the luminal components; and (2) absorbing nutrients. Beneficial commensal intestinal bacteria further supplement the intestinal epithelial barrier by protecting the host from colonization by pathogens [21].
Gut microbiota derived metabolites contribute to intestinal barrier maturation at the suckling-to-weaning transition
Published in Gut Microbes, 2020
Martin Beaumont, Charlotte Paës, Eloïse Mussard, Christelle Knudsen, Laurent Cauquil, Patrick Aymard, Céline Barilly, Béatrice Gabinaud, Olivier Zemb, Sandra Fourre, Roselyne Gautier, Corinne Lencina, Hélène Eutamène, Vassilia Theodorou, Cécile Canlet, Sylvie Combes
The intestinal epithelium is a physicochemical and immunological barrier against luminal antigens and enteric pathogens, yet allowing nutrients and water absorption.1,2 Epithelial cells strictly limit bacterial invasion through a high proliferation rate, mucus secretion, tight junction formation and innate immune responses.3 During the postnatal period, the maturation of the intestinal epithelium has lifelong consequences for gut and immune homeostasis.4 Indeed, disruption of the gut barrier in young animals increases the susceptibility to digestive and infectious diseases later in life.5 Understanding the mechanisms underlying the postnatal maturation of the gut barrier is therefore necessary to develop innovative strategies supporting lifelong intestinal homeostasis.
Strategies and industrial perspectives to improve oral absorption of biological macromolecules
Published in Expert Opinion on Drug Delivery, 2018
Chang Liu, Yongqiang Kou, Xin Zhang, Hongbo Cheng, Xianzhi Chen, Shirui Mao
After crossing the intestinal mucosa, therapeutic proteins via oral administration must traverse through phospholipid bilayer membranes before entering into the systemic circulation. The intestinal epithelium consists of two types of cells: absorptive and secretory cells in terms of their genetic differentiation programs and distinct functions. In the small intestine, the enterocytes function as absorptive cells, comprising ~90% of the small intestinal epithelium. Four additional cell types (goblet, Paneth, enteroendocrine, and tuft cells) are termed secretory cells [13]. In contrast, in the large intestine, Paneth cells are absent and colonocytes are assigned as absorptive cells. Besides, it has long been recognized that cup cells and M cells are still not part of the absorptive or secretory class of epithelial cells. Due to the presence of tight junctions (TJs) between two adjacent monolayers of epithelial cells, the impermeable intestinal epithelium is, however, more than just an absorptive and secretory surface and acts as gatekeeper to macromolecules. Owing to large mass and hydrophilic properties, the oral delivery of therapeutic proteins across epithelia is selectively limited by either paracellular or transcellular pathways. The better understanding of intestinal epithelial barrier function brings forward studies of transport mechanisms for macromolecules, is thereby of common interest.
Related Knowledge Centers
- Epithelium
- Gastrointestinal Tract
- Muscularis Mucosae
- Simple Columnar Epithelium
- Tight Junction
- Lamina Propria
- Small Intestine
- Large Intestine
- Lumen
- Intestinal Mucosal Barrier