Lamina propria of the small intestine

The mucosa of the small intestine is lined by a simple columnar epithelium, which evaginates into villi and invaginates into crypts, as shown schematically in Fig. 10.11. The lamina propria of the small intestine forms the core of villi... 

The different re-nutrition diets not only were able to reestablish the number of immune cells in the lamina propria of the small intestine, but also the functionality of them. Malnutrition induces impairment in the cytokine production by the intestinal immune cells, which was reverted when the re-nutrition diets were supplemented with PFM or BFS, reaching values near to those observed in the well-nourished control group (Figure 8.1). This finding is very important considering the role of cytokines in the enhancement of the immune response during a vaccination process (Rizza et al. 2002). 

Stress influences gut mucosal immune response producing a diminution in the number of IgA+ B-lymphocytes in the lamina propria of the small intestine and in the secretion of S-IgA into the intestinal fluid of stressed animals. The probiotic strain Lact. casei CRL 431 increased these parameters in agreement with another study in a mouse stress model (Jarillo-Luna et al. 2007). The decrease in IgA+ cell numbers in stressed mice could be due to high levels of glucocorticoids that induce apoptosis of B cells in the lamina propria of the gut (Fukuzuka et al. 2000 Brunner et al. 2001 Ruiz-Santana et al. 2001). Another possibility could be the low number of CD4+ T cells. These last cells produce cytokines such as IFNy, IL-6, IL-5, IL-4, and IL-10, which are involved in the expansion and differentiation of IgA+ B cells (Iwakabe et al. 1998 Elenkov 2004 Brandtzaeg and Johansen 2005). These cell populations increased in stressed animals consuming probiotics. 

Macrophages and DC are very important in innate and adaptive immunity, and CD lib and CD 11 c are used respectively as markers to identify them. In the gut, these cells are involved in the bacterial clearance to avoid invasion of translocating bacteria from the intestinal lumen to deep tissues and to maintain intestinal homeostasis. In previous work, we demonstrated that the main mechanism by which the probiotic strain Lact. casei CRL 431 influences the gut mucosal immunity is through activation of the innate immune response (Maldonado Galdeano and Perdigdn 2006). For this reason we analyzed whether the stress induced changes in the expression of both markers in the immune cells present in the lamina propria of the small intestine of mice. The number of CDllb+ cells... 

In addition, we demonstrated that the probiotic Lact. casei CRL 431 improves immune parameters related to the intestinal barrier, such as the S-IgA and the number of macrophages and DC in the lamina propria of the small intestine (Palomar et al. 2014). 

The third mucosal layer is that lining the entire length of the small intestine and which represents a continuous sheet of epithelial cells. These epithelial cells (or enterocytes) are columnar in shape, and the luminal cell membrane, upon which the microvilli reside, is called the apical cell membrane. Opposite this membrane is the basal (or basolateral) plasma membrane, which is separated from the lamina propria by a basement membrane. A sketch of this cell is shown in Fig. 5. The primary function of the villi is absorption. 

Figure 8.1 (A) Cross-sectional view of the organization of the small intestine, illustrating the serosa, the longitudinal and circular muscle layers (=muscularis externa), the submucosa, and the intestinal mucosa. The intestinal mucosa consists of four layers, the inner surface cell monolayer of enterocytes, the basal membrane, the lamina propria (connective tissue, blood capillaries), and the muscularis mucosae, (B) Schematic representation of an enterocyte (small intestinal epithehal cell) (according to Tso and Crissinger [151], with permission).

The epithelium is supported underneath by lamina propria and a layer of smooth muscle called muscularis mucosa (3-10 cells thick). These three layers, i.e., the epithelium, lamina propria, and muscularis mucosa, together constitute the intestinal mucosa.On the apical surface, the epithelium along with lamina propria projects to form villi. The cell membranes of epithelial cells that comprise the villi contain uniform microvilli, which give the cells a fuzzy border, collectively called a brush border. These structures, although greatly increase the absorptive surface area of the small intestine, provide an additional enzymatic barrier since the intestinal digestive enzymes are contained in the brush border. In addition, on the top of the epithelial layer lies another layer, the UWL, as previously described. The metabolic and biochemical components of the epithelial barrier will be discussed. 

Mucous Surface. The mucosa of the small intestine consists of three layers (Fig. 2) an absorptive layer, a continuous single sheet of columnar epithelium the lamina propria, a layer heterogeneous in composition and cell type and the muscularis mucosa, a muscular layer separating the mucosa and submucosa. 

In animal studies, when the AZA is administered per os, it caused degeneration of epithelial cells and necrosis of the lamina propria in the villi of the small intestine and in lymphoid tissues such as thymus, spleen, and the Peyer s patches fat accumulation in the liver and degeneration of hepatocytes reduction of nongranulocytes and damage to T- and B-cells in the spleen. Overall, AZAl induced a far greater degree of tissue injury and slower recovery time when compared with OA [62,63]. 

Figure 1 Physiological model for sequential intestinal and hepatic first-pass metabolism. Blood flow to the small intestine is functionally divided into mucosal (Qgm) and serosal (Qgs) blood flow. Mucosal blood flow in the lamina propria perfuses the enterocyte epithelium. Portal blood flow (Qpv), which perfuses the liver is comprised of blood leaving the small intestine and other splanchnic organs such as the stomach and spleen. Blood flow leaving the liver (Qhv) represents the sum of hepatic arterial flow (<2ha) and Qpv. First-pass metabolism of an orally administered substrate (S) to product (P) may occur in the enterocyte or hepatocyte.

In contrast, in the small intestine (Figure 3.15), the mucosa is composed of surface projections or villi with a core of lamina propria and muscle fibers. In the lamina propria itself are found intestinal glands, fine connective tissues, reticular cells, and lymphatic tissue. The submucosa is filled with glands in the duodenum whereas in the muscularis externa an inner circular layer and an outer longitudinal layer of muscle are present. Parasym-... 

Morphological studies have demonstrated the presence of cells in the GI tract that contain dopamine and express components of dopamine signaling pathways, including catecholamine biosynthetic enzymes and specific dopamine receptors and transporters. In tlie stomach, tyrosine hydroxylase is expressed in epithelial cells, including acid-secreting parietal cells. In the small intestine, cells of the lamina propria, including immune cells, also express tyro-... 

Rotaviruses are double-stranded wheel-shaped RNA viruses. These strains cause diarrhea by infecting the enterocyts of the villi in the small intestine. Changes to the villi include shortening of villus height, crypt hyperplasia, and mononuclear cell infiltration of the lamina propria. Diarrhea results from decreased absorption across intestinal mucosal surface. ... 

When examined, the jejunum of these patients shows signs of crypt extension, disruption or loss of the brush border, as well as an extensive infiltrate of polymorphonuclear cells and macrophages into the lamina propria. Diarrhea in staphylococcal food poisoning may be due to the inhibition of water and electrolyte reabsorption in the small intestine by SEs as observed in vitro [76] and in an animal model [77],... 

As shown in Figure 36.9a, with synthetic AZA-1, the liver showed changes similar to those seen with the natural compound, seen in Figure 36.1 (a and b), namely, fatty degeneration and sporadic necrotized hepatocytes. The small intestine erosion and characteristic changes of late recovery at lamina propria were confirmed (Figure 36.9a-i and ii). 

FIGURE 36.9 (a) Synthetic AZA-1 (24 h) injured the liver and the small intestine. Erosion still be seen after 24 h (i), and characteristic change of late recovery at empty lamina propria can be seen in (ii). (b) Isomer injured the liver but ballooning hepatocytes appeared at central area, and did not injure small intestinal villi. 

Figure 3.15. Structure of small intestine. In small intestine, the mucosa contains villi or surface projections, lamina propria, and muscle fibers. Submucosa contains duodenal glands, and the muscularis contains muscle fibers.

Gastrointestinal Gastrointestinal adverse events are among the main limitations of the use of mycophenolate mofetil. Examination of the surface epithelium, lamina propria, and crypts of mucosal intestinal biopsy tissue in 15 multivisceral transplant patients, including stomach, small intestine, and colon, showed neither specific changes that could be associated with mycophenolate mofetil toxicity nor changes that could differentiate mycophenolate mofetil-related toxicity from acute rejection [88 ]. 

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