Elevated expression of hyaluronan and its CD44 receptor in the duodenal mucosa of coeliac patients

The Impact of Post-transcriptional Control: Better Living Through RNA Regulons

Traditionally, cancer is viewed as a disease driven by genetic mutations and/or epigenetic and transcriptional dysregulation. While these are undoubtedly important drivers, many recent studies highlight the disconnect between the proteome and the genome or transcriptome. At least in part, this disconnect arises as a result of dysregulated RNA metabolism which underpins the altered proteomic landscape observed. Thus, it is important to understand the basic mechanisms governing post-transcriptional control and how these processes can be co-opted to drive cancer cell phenotypes. In some cases, groups of mRNAs that encode protein involved in specific oncogenic processes can be co-regulated at multiple processing levels in order to turn on entire biochemical pathways. Indeed, the RNA regulon model was postulated as a means to understand how cells coordinately regulate transcripts encoding proteins in the same biochemical pathways. In this review, we describe some of the basic mRNA processes that are dysregulated in cancer and the biological impact this has on the cell. This dysregulation can affect networks of RNAs simultaneously thereby underpinning the oncogenic phenotypes observed.

Matrix expansion and syncytial aggregation of syndecan-1+ cells underpin villous atrophy in coeliac disease

Background

We studied the expression of sulphated glycosaminoglycans (GAGs) in coeliac disease (CD) mucosa, as they are critical determinants of tissue volume, which increases in active disease. We also examined mucosal expression of IL-6, which stimulates excess GAG synthesis in disorders such as Grave's ophthalmopathy.

Methods

We stained archival jejunal biopsies from 5 children with CD at diagnosis, on gluten-free diet and challenge for sulphated GAGs. We then examined duodenal biopsies from 9 children with CD compared to 9 histological normal controls, staining for sulphated GAGs, heparan sulphate proteoglycans (HSPG), short-chain HSPG (Δ-HSPG) and the proteoglycan syndecan-1 (CD138), which is expressed on epithelium and plasma cells. We confirmed findings with a second monoclonal in another 12 coeliac children. We determined mucosal IL-6 expression by immunohistochemistry and PCR in 9 further cases and controls, and used quantitative real time PCR for other Th17 pathway cytokines in an additional 10 cases and controls.

Results

In CD, HSPG expression was lost in the epithelial compartment but contrastingly maintained within an expanded lamina propria. Within the upper lamina propria, clusters of syndecan-1+ plasma cells formed extensive syncytial sheets, comprising adherent plasma cells, lysed cells with punctate cytoplasmic staining and shed syndecan ectodomains. A dense infiltrate of IL-6⁺ mononuclear cells was detected in active coeliac disease, also localised to the upper lamina propria, with significantly increased mRNA expression of IL-6 and IL-17A but not IL-23 p19.

Conclusions

Matrix expansion, through syndecan-1+ cell recruitment and lamina propria GAG increase, underpins villous atrophy in coeliac disease. The syndecan-1+ cell syncytia and excess GAG production recapitulate elements of the invertebrate encapsulation reaction, itself dependent on insect transglutaminase and glutaminated early response proteins. As in other matrix expansion disorders, IL-6 is upregulated and represents a logical target for immunotherapy in patients with coeliac disease refractory to gluten-free diet.

Variants within protectin (CD59) and CD44 genes linked to an inherited haplotype in a family with coeliac disease

Coeliac disease (CD) is an autoimmune disorder characterised by inflammation, villous atrophy and hyperplasia of the small intestinal mucosa that affects genetically susceptible individuals. A genome-wide scan was performed in 17 family members with high incidence of CD. Highest nonparametric linkage (NPL) and logarithm of odds (LOD) scores were of 6.21 (P = 0.0107) and 2.57, respectively, to a region on chromosome 11p13-12. Following fine mapping, NPL and LOD scores did not change, but the linkage interval on chromosome 11 was narrowed to a region that is approximately 50.94 cM from pTer. Two inherited haplotypes on chromosomes 11p13-12 and 9q21 were observed in all affected members but not in the majority of clinically normal individuals. Sequencing of genes at region 11p13-12 showed a number of sequence variants, two of which were linked with the inherited haplotype. One of these variants in the CD59 gene was found at a very low frequency in the population and could possibly affect pre-messenger RNA splicing. This study is of particular importance for the identification of novel genes that might be responsible for CD other than human leukocyte antigen.

Hyaluronan in human tumors: pathobiological and prognostic messages from cell-associated and stromal hyaluronan

Cancers are supported by a distinct type of connective tissue stroma, crucial for tumor survival and advancement. Hyaluronan is a major matrix molecule in the stroma of many common tumors, and involved in their growth and spreading. Here we focus in recent data on stromal hyaluronan in human tumors, and that on the surface of the malignant cells. Hyaluronan accumulation is most conspicuous in malignancies that develop in cells and tissues normally devoid of hyaluronan, such as single layered epithelia and their hyaluronan-poor connective tissue stroma. The magnitude of the hyaluronan accumulation in the malignant epithelium itself (e.g. colon and gastric cancers) or tumor stroma (breast, ovarian, prostate cancers) strongly correlates with an unfavorable prognosis of the patient, i.e. advancement of the malignancy. A completely different pattern arises from stratified epithelia that normally produce hyaluronan and are surrounded by a hyaluronan-rich stroma. The cell surface of the latter group of tumors (e.g. squamous cell carcinomas of skin, mouth, larynx and esophagus, and skin melanoma) show abundant hyaluronan which tends to get reduced and patchy in the most advanced stages of the tumors, suggesting enhanced turnover. While the assays of human tumors represent snapshots of currently unknown processes and kinetics of hyaluronan metabolism, it is obvious that hyaluronan accumulation at some stage is an inherent feature in most of the common epithelial malignant tumors. The possible contributions of inflammatory cells, stem cells, mutated stromal cells, or otherwise deranged growth factor exchange between stromal and cancer cells are discussed as possible explanations to hyaluronan abundance in the tumors. The importance of hyaluronan in human tumor progression will be further clarified when drugs become available to modify hyaluronan metabolism.

Alteration of the expression of CD44 [corrected] isoforms in oral epithelia and saliva from patients with oral lichen planus

Oral lichen planus (OLP) is a chronic inflammatory mucosal disease that cell-mediated immunological mechanisms are involved in pathogenesis. The objective of this study was to investigate the expression of CD44 isoforms including CD44s, CD44v5, and CD44v6 in biopsy specimens and saliva from OLP patients. Thirty-one OLP patients and 30 healthy subjects were enrolled in this study. Immunohistochemical methods were used to detect the expression of CD44 isoforms in oral epithelia, and enzyme-linked immunosorbent assay (ELISA) was performed to measure levels of salivary CD44 isoforms. Our results demonstrated that expression of CD44v6 in oral epithelia from OLP patients was significantly decreased in comparison to controls (p = 0.021). Levels of salivary CD44s and CD44v5 from OLP patients were significantly higher than those from controls (p = 0.007 and p = 0.002, respectively). In summary, our findings provided additional evidence that the pathological stress, such as chronic inflammation, altered the expression of CD44 isoforms in oral epithelia and saliva of OLP patients.

Effect of vitamin A on the CD44 expression in the small intestine of rats with obstructive jaundice

HYPOTHESIS

In this study, the influence of obstructive jaundice on the CD44 expression in the rat small intestine and the alterations of this CD44 expression by vitamin A given intraperitoneally (200 IU/g/day) are evaluated.

MATERIALS AND METHODS

In a prospective animal model study, 32 Sprague-Dawley rats were randomized into four groups: group A rats (n = 8) underwent sham operation and were given daily saline intraperitoneally for 2 weeks (sham + saline); group B animals (n = 8) underwent sham operation and were given daily vitamin A intraperitoneally for 2 weeks (sham + vitamin A); group C rats (n = 8) underwent common bile duct ligation and were given daily saline intraperitoneally for 2 weeks (obstructive jaundice + saline), and group D animals (n = 8) underwent common bile duct ligation and were given daily vitamin A intraperitoneally for 2 weeks (obstructive jaundice + vitamin A). After 2 weeks, standardized jejunum and ileum segments were harvested from all animals. The expression of CD44 on the cell surface was evaluated immunohistochemically. Comparisons among the four groups were done.

RESULTS

The plasma bilirubin, aspartate transaminase, alanine transaminase, alkaline phospatase, and gamma-glutamyltransferase levels in groups C and D (obstructive jaundice groups) were higher than those in groups A and B (sham groups; p < 0.05). There was no difference between groups A and B (sham groups) with regard to the number of cells expressing surface CD44 in jejunum and ileum. When groups A and B were compared with group C (obstructive jaundice + saline) animals, the number of cells expressing surface CD44 was significantly decreased in both jejunum and ileum in group C. The difference between sham groups (A and B) and group C was found to be significant (p < 0.05). When group D (obstructive jaundice + vitamin A) was compared with group C (obstructive jaundice + saline), the number of cells expressing surface CD44 was significantly increased in jejunum and ileum in group D animals (p < 0.05), higher than in the sham groups (A and B). The difference between group D and sham groups (A and B) was found to be significant (p < 0.05).

CONCLUSION

Obstructive jaundice for 2 weeks significantly decreased the CD44 expression in the rat small intestine. We found that daily intraperitoneal administration of vitamin A in rats with obstructive jaundice for 2 weeks significantly restored the impaired CD44 expression.