The role of intermediate filaments in maintaining integrity and function of intestinal epithelial cells after massive bowel resection in a rat

EV-A71 Mechanism of Entry: Receptors/Co-Receptors, Related Pathways and Inhibitors

Enterovirus A71, a non-enveloped single-stranded (+) RNA virus, enters host cells through three stages: attachment, endocytosis and uncoating. In recent years, receptors/co-receptors anchored on the host cell membrane and involved in this process have been continuously identified. Among these, hSCARB-2 was the first receptor revealed to specifically bind to a definite site of the EV-A71 viral capsid and plays an indispensable role during viral entry. It actually acts as the main receptor due to its ability to recognize all EV-A71 strains. In addition, PSGL-1 is the second EV-A71 receptor discovered. Unlike hSCARB-2, PSGL-1 binding is strain-specific; only 20% of EV-A71 strains isolated to date are able to recognize and bind it. Some other receptors, such as sialylated glycan, Anx 2, HS, HSP90, vimentin, nucleolin and fibronectin, were discovered successively and considered as "co-receptors" because, without hSCARB-2 or PSGL-1, they are not able to mediate entry. For cypA, prohibitin and hWARS, whether they belong to the category of receptors or of co-receptors still needs further investigation. In fact, they have shown to exhibit an hSCARB-2-independent entry. All this information has gradually enriched our knowledge of EV-A71's early stages of infection. In addition to the availability of receptors/co-receptors for EV-A71 on host cells, the complex interaction between the virus and host proteins and various intracellular signaling pathways that are intricately connected to each other is critical for a successful EV-A71 invasion and for escaping the attack of the immune system. However, a lot remains unknown about the EV-A71 entry process. Nevertheless, researchers have been continuously interested in developing EV-A71 entry inhibitors, as this study area offers a large number of targets. To date, important progress has been made toward the development of several inhibitors targeting: receptors/co-receptors, including their soluble forms and chemically designed compounds; virus capsids, such as capsid inhibitors designed on the VP1 capsid; compounds potentially interfering with related signaling pathways, such as MAPK-, IFN- and ATR-inhibitors; and other strategies, such as siRNA and monoclonal antibodies targeting entry. The present review summarizes these latest studies, which are undoubtedly of great significance in developing a novel therapeutic approach against EV-A71.

Intestinal dysmotility after bowel resection in rats is associated with decreased ghrelin and vimentin expression and loss of intestinal cells of Cajal

This study provides novel insight into the mechanisms of intestinal dysmotility following massive small bowel resection. We show that 2 wk after bowel resection in rats, impaired intestinal motility was associated with loss of interstitial cells of Cajal (ICC; downregulation of transmembrane member 16A (TMEM16A) and c-kit expression) as well as with decreased vimentin, desmin, and ghrelin levels. Impaired intestinal motility led to a decrease in final body weight, suggesting less effective nutrient absorption. The purpose of this study was to evaluate the mechanisms of intestinal motility in a rat model of short bowel syndrome (SBS). Rats were divided into three groups: Sham rats underwent bowel transection; SBS-NSI rats underwent a 75% bowel resection and presented with normal intestinal size (NSI) at euthanasia and hypermotility patterns; SBS-DYS showed dysmotile (DYS) enlarged intestine and inhibited motility patterns. Animals were euthanized after 2 wk. Illumina's digital gene expression (DGE) analysis was used to determine the intestinal motility-related gene expression profiling in mucosal samples. Intestinal motility-related and ICC genes and protein expression in intestinal muscle layer were determined using real-time PCR, Western blotting, and immunohistochemistry. Gastrointestinal tract motility was studied by microcomputer tomography. From 10 Ca²⁺ signaling pathway-related genes, six genes in jejunum and seven genes in ileum were downregulated in SBS vs. Sham animals. Downregulation of TMEM16A mRNA and protein was confirmed by real-time PCR. Rapid intestinal transit time in SBS-NSI rats correlated with a mild decrease in TMEM16A, c-kit, and vimentin mRNA and protein expression (vs/. Sham animals). SBS-DYS rats demonstrated enlarged intestinal loops and delayed small intestinal emptying (on imaging studies) that were correlated with marked downregulation in TMEM16A, c-kit, vimentin, and ghrelin mRNA and protein levels compared with the other two groups. In conclusion, 2 wk following massive bowel resection in rats, impaired intestinal motility was associated with decreased vimentin and ghrelin gene and protein levels as well as loss of ICC (c-kit and TMEM16A).NEW & NOTEWORTHY This study provides novel insight into the mechanisms of intestinal dysmotility following massive small bowel resection. We show that 2 weeks after bowel resection in rats, impaired intestinal motility was associated with loss of interstitial cells of Cajal (downregulation of TMEM 16A, and c-kit expression) as well as with decreased vimentin, desmin, and ghrelin levels. Impaired intestinal motility led to decrease in final body weight, suggesting less effective nutrient absorption.

Anti-TNF-α Therapy Exerts Intestinal Anti-inflammatory and Anti-apoptotic Effects After Massive Bowel Resection in a Rat

OBJECTIVES

The aim of this study was to examine the effect of massive small bowel resection on proinflammatory cytokine intestinal expression and the effect of anti-TNF-α antibodies (ATA) on intestinal inflammation, epithelial cell turnover, and intestinal adaptation after bowel resection in rats.

METHODS

Male Sprague-Dawley rats were divided into 4 experimental groups: Sham-rats underwent bowel transection; Sham-ATA rats underwent bowel transection and were treated with ATA; SBS-animals underwent 75% bowel resection; and SBS-ATA rats underwent bowel resection and were treated with ATA similarly to Group B. Parameters of intestinal adaptation, enterocyte proliferation, and apoptosis were determined at sacrifice. TNF-α and apoptosis-related gene and protein levels were determined by Illumina's Digital Gene Expression (DGE) analysis, Real Time PCR, Western blotting, and immunohistochemistry.

RESULTS

From 25 genes related to TNF-α signalling that were investigated, 8 genes in the jejunum and 10 genes in the ileum were found to be up-regulated in resected versus sham animals. SBS rats demonstrated a significant increase in tissue and plasma TNF-α, IL-6 levels, intestinal mucosal TNF-α related gene expression, and microscopic parameters of inflammation. Treatment of resected animals with ATA resulted in a significant decrease in TNF-α levels, intestinal mucosal TNF-α-related gene expression, decreased number of intraepithelial lymphocytes and macrophages, and lower apoptotic index compared with SBS animals.

CONCLUSIONS

In a rat model of SBS, ATA decreased plasma and tissue TNF-α levels, diminished mucosal inflammation, and inhibited cell apoptosis. Anti-apoptotic effects of ATA appear to be associated with an inhibited extrinsic apoptotic pathway.

High sucrose diet induces morphological, structural and functional impairments in the renal tubules of Drosophila melanogaster: A model for studying type-2 diabetes mediated renal tubular dysfunction

Continuous feeding of high dietary sugar is strongly associated with type 2 diabetes (T2D) and its secondary complications. Diabetic nephropathy (DN) is a major secondary complication that leads to glomerular and renal tubular dysfunction. The present study is aimed to investigate the effects of chronic exposure of high sugar diet (HSD) on renal tubules. Malpighian tubules (MTs), a renal organ of Drosophila, were used as a model in the study. Feeding of HSD develops T2D condition in Drosophila. The MTs showed structural abnormalities in 20 days of HSD fed flies. Impaired insulin signaling, oxidative stress, enhanced levels of AGE-RAGE and induction of apoptosis were observed in the MTs of these flies. Further, altered expression of transporters, enhanced uric acid level and reduced fluid secretion rate confirmed the impaired function of MTs in these flies. RNA-seq and RT-PCR analyses in the MTs of HSD fed-and control-flies revealed the altered expression of candidate genes that regulate several important pathways including extracellular matrix (ECM), advanced glycation end products-receptor for advanced glycation end products (AGE-RAGE), transforming growth factor β (TGF-β), galactose, starch and sucrose metabolism that are well known mediators of renal tubular dysfunction in DN patients. Disruption of insulin signaling in the MTs also causes renal tubular dysfunction similar to HSD fed flies. Overall, the study suggests that phenotypes observed in the MTs of HSD fed flies recapitulate several hallmarks of renal tubular dysfunction in DN patients. Therefore, we conclude that MTs of HSD fed flies may be used for deciphering the underlying mechanisms of T2D mediated renal tubular dysfunction.

Is maintenance of the ileocecal valve important to the intestinal adaptation mechanisms in a weaning rat model of short bowel?

PURPOSE

To evaluate the role of maintenance of the ileocecal valve (ICV) in intestinal adaptation mechanisms, in a weaning rat experimental model of short bowel.

METHODS

Forty animals were operated on to produce short bowel syndrome. They were divided into five groups: maintenance (MV) or resection of ICV (RV), kill after 4 days (MV4 and RV4) or 21 days (MV21 and RV21), and a control group (21-day-old rats). Body weights, small bowel and colon lengths and diameters, villus heights, crypt depths, lamina propria and muscle layer thickness, as well as the apoptosis index of villi and crypts and expression of pro- and anti-apoptotic genes, were studied.

RESULTS

Preservation of the ICV promoted increased weight gain (p = 0.0001) and intestinal villus height after 21 days; crypt depth was higher in comparison to controls. It was verified a higher expression of Ki-67 in bowel villi and crypts (p = 0.018 and p = 0.015, respectively) in RV4 group and a higher expression in bowel villi of MV4 group animals (p = 0.03). The maintenance of ICV promoted late increased expression of the anti-apoptotic gene Bcl-XL in the colon (p = 0.043, p = 0.002, p = 0.01).

CONCLUSION

The maintenance of the ICV led to positive changes in this model.