STAT6 expression and IL-13 production in association with goblet cell hyperplasia and worm expulsion of Gymnophalloides seoi from C57BL/6 mice

Echinostomes and Other Intestinal Trematode Infections

Intestinal trematodes are among the most common types of parasitic worms. About 76 species belonging to 14 families have been recorded infecting humans. Infection commonly occurs when humans eat raw or undercooked foods that contain the infective metacercariae. These parasites are diverse in regard to their morphology, geographical distribution and life cycle, which make it difficult to study the parasitic diseases that they cause. Many of these intestinal trematodes have been considered as endemic parasites in the past. However, the geographical limits and the population at risk are currently expanding and changing in relation to factors such as growing international markets, improved transportation systems, new eating habits in developed countries and demographic changes. These factors make it necessary to better understand intestinal trematode infections. This chapter describes the main features of human intestinal trematodes in relation to their biology, epidemiology, host-parasite relationships, pathogenicity, clinical aspects, diagnosis, treatment and control.

Role of Goblet Cells in Intestinal Barrier and Mucosal Immunity

Goblet cells and the mucus they secrete serve as an important barrier, preventing pathogens from invading the mucosa to cause intestinal inflammation. The perspective regarding goblet cells and mucus has changed, with current evidence suggesting that they are not passive but play a positive role in maintaining intestinal tract immunity and mucosal homeostasis. Goblet cells could obtain luminal antigens, presenting them to the underlying antigen-presenting cells (APCs) that induces adaptive immune responses. Various immunomodulatory factors can promote the differentiation and maturation of goblet cells, and the secretion of mucin. The abnormal proliferation and differentiation of goblet cells, as well as the deficiency synthesis and secretion of mucins, result in intestinal mucosal barrier dysfunction. This review provides an extensive outline of the signaling pathways that regulate goblet cell proliferation and differentiation and control mucins synthesis and secretion to elucidate how altering these pathways affects goblet functionality. Furthermore, the interaction between mucins and goblet cells in intestinal mucosal immunology is described. Therefore, the contribution of goblet cells and mucus in promoting gut defense and homeostasis is illustrated, while clarifying the regulatory mechanisms involved may allow the development of new therapeutic strategies for intestinal disorders.

The Interplay between Nutrition, Innate Immunity, and the Commensal Microbiota in Adaptive Intestinal Morphogenesis

The gastrointestinal tract is a functionally and anatomically segmented organ that is colonized by microbial communities from birth. While the genetics of mouse gut development is increasingly understood, how nutritional factors and the commensal gut microbiota act in concert to shape tissue organization and morphology of this rapidly renewing organ remains enigmatic. Here, we provide an overview of embryonic mouse gut development, with a focus on the intestinal vasculature and the enteric nervous system. We review how nutrition and the gut microbiota affect the adaptation of cellular and morphologic properties of the intestine, and how these processes are interconnected with innate immunity. Furthermore, we discuss how nutritional and microbial factors impact the renewal and differentiation of the epithelial lineage, influence the adaptation of capillary networks organized in villus structures, and shape the enteric nervous system and the intestinal smooth muscle layers. Intriguingly, the anatomy of the gut shows remarkable flexibility to nutritional and microbial challenges in the adult organism.

The relationship between intestinal goblet cells and the immune response

Goblet cells (GCs) are single-cell glands that produce and secrete mucin. Mucin forms a mucus layer, which can separate the materials in cavities from the intestinal epithelium and prevent the invasion of pathogenic microorganisms in various ways. GCs can also participate in the immune response through nonspecific endocytosis and goblet cell-associated antigen passages (GAPs). GCs endocytose soluble substances from the lumen and transmit antigens to the underlying antigen-presenting cells (APCs). A variety of immuno-regulatory factors can promote the differentiation, maturation of GCs, and the secretion of mucin. The mucin secreted by GCs forms a mucus layer, which plays an important role in resisting the invasion of foreign bacteria and intestinal inherent microorganisms, regulating the immune performance of the body. Therefore, the present study mainly reviews the barrier function of the mucus layer, the mucus secreted by goblet cells, the protective effect against pathogenic bacteria, the delivery of luminal substances through GAPs and the relationship between GCs and the immune response.

肠道杯状细胞及其功能研究进展

杯状细胞(goblet cell, GC)由肠黏膜基底干细胞分化而来, 形似高脚杯, 内含黏液颗粒, 黏液颗粒的组成成分主要为黏蛋白. MUC2是一种重要的拥有特殊网状结构的黏蛋白. GC分泌黏液到肠上皮细胞形成黏液层填补细胞间隙. 黏液层使得GC能在肠黏膜抵御内外源侵袭时发挥重要作用, 尤其是将上皮与肠道菌分离, 从而能维持肠道微生态平衡. 除此之外, GC还能接受和参与免疫调节. 更重要的是GC及其分泌黏蛋白的缺陷与肠道多种疾病密切相关. 总之, GC对肠道健康的作用不容小视.

Developmental expression of STATs, nuclear factor-κB and inflammatory genes in the jejunum of piglets during weaning

The signal transducer and activator of transcription (STAT) proteins play essential roles in apoptosis, proliferation and survival. However, the role of STATs in intestinal inflammation during weaning is unclear. This study aimed to investigate developmental expression of STATs, nuclear factor-κB (NF-κB) and inflammatory genes in the jejunum of piglets during weaning. Thirty-two piglets were weaned at 21d and sacrificed at 0, 1, 7, or 14d (n=8) after weaning. Villus height and the villus height/crypt depth ratio were decreased, whereas crypt depth was increased in the jejunum at 7 and 14d after weaning. In addition, the mRNA levels of interferon-γ (IFN-γ), inducible nitric oxide synthase (iNOS), IL-6, IL-8, IL-12 and IL-22 were increased in the jejunum at 7 and 14d after weaning, whereas transforming growth factor-β (TGF-β), suppressor of cytokine signaling 3 (SCOS3) and arginase-1 was decreased. Neutrophil infiltration was increased in the mucosa of the jejunum after weaning. Moreover, phosphorylation of IκB-α, NF-κB, AKT and STAT-3 was increased. However, the phosphorylation of STAT-1 (at 7 and 14d) and STAT-6 (at 1 and 7d) was suppressed in the jejunum after weaning. Treatment of porcine jejunal epithelial (IPEC-J2) cells with the STAT inhibitors fludarabine, niclosamide and teriflunomide, which inhibit the phosphorylation of STAT-1, STAT-3 and STAT-6, respectively, weakened the defense capacity of these cells against bacterial infection. In conclusion, weaning caused severe inflammation associated with activation of the NF-κB and STAT-3 pathways and suppression of STAT-1 and STAT-6 in the jejunum of piglets.

Increased intestinal epithelial cell turnover and intestinal motility in Gymnophalloides seoi-infected C57BL/6 mice

The changing patterns of goblet cell hyperplasia, intestinal epithelial cell turnover, and intestinal motility were studied in ICR and C57BL/6 mice infected with Gymnophalloides seoi (Digenea: Gymnophallidae). Whereas ICR mice retained G. seoi worms until day 7 post-infection (PI), C57BL/6 mice showed a rapid worm expulsion within day 3 PI. Immunosuppression with Depo-Medrol significantly delayed the worm expulsion in C57BL/6 mice. Goblet cell counts were increased in both strains of mice, peaking at day 1 PI in C57BL/6 mice and slowly increasing until day 7 PI in ICR mice. In C57BL/6 mice infected with G. seoi, newly proliferating intestinal epithelial cells were remarkably increased in the crypt, and the increase was the highest at day 1 PI. However, in ICR mice, newly proliferating intestinal epithelial cells increased slowly from day 1 to day 7 PI. Intestinal motility was increased in G. seoi-infected mice, and its chronological pattern was highly correlated with the worm load in both strains of mice. Meanwhile, immunosuppression of C57BL/6 mice abrogated the goblet cell proliferation, reduced the epithelial cell proliferation, and suppressed the intestinal motility. Goblet cell hyperplasia, increased intestinal epithelial cell turnover, and increased intestinal motility should be important mucosal defense mechanisms in G. seoi-infected C57BL/6 mice.