Role of MutS homolog 2 (MSH2) in intestinal myofibroblast proliferation during Crohn's disease stricture formation

Intestinal Stromal Cells in the Turmoil of Inflammation and Defective Connective Tissue Remodeling in Inflammatory Bowel Disease

In steady state, intestinal subepithelial myofibroblasts form a thin layer below the basement membrane. Unlike the rest of the stromal cells in the lamina propria, they express tensile proteins, guide epithelial regeneration, and sense luminal microbiota. Upon inflammation in inflammatory bowel disease (IBD), they express activation markers, accept trophic signaling by infiltrating neutrophils and macrophages, and are activated by cytokines from helper T cells to produce a narrow spectrum of cytokines and a wider spectrum of chemokines, attract cells of innate and adaptive immunity, orchestrate inflammatory responses, and qualitatively and quantitatively modify the extracellular matrix. Thus, beyond being structural tissue components, they assume active roles in the pathogenesis of complicated IBD. Discrimination between myofibroblasts and fibroblasts may be an oversimplification in light of single-cell sequencing data unveiling the complexity of multiple phenotypes of stromal cells with distinct roles and plasticity. Spatial transcriptomics revealed distinct phenotypes by histologic localization and, more intriguingly, the assembly of mucosal neighborhoods that support spatially distinct functions. Current IBD treatments target inflammation but fail in fibrostenotic or fistulizing disease. Baseline and recent findings on stromal cells, molecules, and pathways involved in disrupted extracellular matrix homeostasis are reviewed to provide relevant pharmacologic targets.

Resistance to apoptosis in complicated Crohn's disease: Relevance in ileal fibrosis

BACKGROUND AND AIMS

The stiffening of the extracellular matrix, and changes in its cellular and molecular composition, have been reported in the pathogenesis of fibrosis. We analyze the mechanisms that perpetuate ileal fibrosis in surgical resections of complicated Crohn's disease patients.

METHODS

Ileal resections were obtained from affected and non-affected tissue of stenotic or penetrating Crohn's disease behavior. Ilea from non-IBD patients were used as control tissue. All samples underwent RNA sequencing. Human small intestinal fibroblasts were treated for 48 h with IL-1β, TFGβ1, PDGFB or TNF-α. Resistance to apoptosis was analysed by RT-PCR, western blot and immunohistochemistry in ileal tissue and by RT-PCR and FACS in cultured cells.

RESULTS

Growth factor-driven signaling pathways and increased RAS GTPase activity were up-regulated in affected ilea in which we found expression of both the antiapoptotic molecule MCL1 and the transcription factor ETS1 in submucosal fibroblasts, and a senescence-associated secretory phenotype. In cultured intestinal fibroblasts, PDGFB induced an ETS1-mediated resistance to apoptosis that was associated with the induction of both of TGFB1 and IL1B, a cytokine that replicated the expression of SASP detected in ileal tissue. ETS1 drove fibroblast polarization between inflammatory and fibrogenic phenotypes in IL1β-treated cells.

CONCLUSIONS

Our data show resistance to apoptosis in complicated ileal CD, and demonstrate that PDGFB induce an ETS1-mediated resistance to apoptosis associated with an inflammatory and fibrogenic pattern of expression in intestinal fibroblasts. Results point to PDGFRB, IL1R1 or MCL1 as potential targets against ileal fibrosis.

Telomerase reverse transcriptase (TERT) - enhancer of zeste homolog 2 (EZH2) network regulates lipid metabolism and DNA damage responses in glioblastoma

Elevated expression of enhancer of zeste homolog 2 (EZH2), a histone H3K27 methyltransferase, was observed in gliomas harboring telomerase reverse transcriptase (TERT) promoter mutations. Given the known involvement of TERT and EZH2 in glioma progression, the correlation between the two and subsequently its involvement in metabolic programming was investigated. Inhibition of human telomerase reverse transcriptase either pharmacologically or through genetic manipulation not only decreased EZH2 expression, but also (i) abrogated FASN levels, (ii) decreased de novo fatty acid accumulation, and (iii) increased ataxia-telangiectasia-mutated (ATM) phosphorylation levels. Conversely, diminished TERT and FASN levels upon siRNA-mediated EZH2 knockdown indicated a positive correlation between TERT and EZH2. Interestingly, ATM kinase inhibitor rescued TERT inhibition-mediated decrease in FASN and EZH2 levels. Importantly, TERT promoter mutant tumors exhibited greater microsatellite instability, heightened FASN levels and lipid accumulation. Coherent with in vitro findings, pharmacological inhibition of TERT by costunolide decreased lipid accumulation and elevated ATM expression in heterotypic xenograft glioma mouse model. By bringing TERT-EZH2 network at the forefront as driver of dysregulated metabolism, our findings highlight the non-canonical but distinct role of TERT in metabolic reprogramming and DNA damage responses in glioblastoma.

Potential Immunomodulatory Effects of Statins in Inflammatory Bowel Disease

Statins are among the most widely prescribed medications in the world. In addition to lowering cholesterol, statins have been shown to have immunomodulatory effects in multiple studies. For example, statins modulate the interaction between T cells and antigen-presenting cells, resulting in decreased T-cell activation and reduced levels of inflammatory cytokines. Statins have also been demonstrated to inhibit the migration of leukocytes across vascular endothelium into tissues. Although most research on the immune effects of statins has been conducted in the context of cardiovascular, rheumatological, or metabolic disease, various studies have shown that statins may have a significant impact on intestinal immunity and mucosal inflammation. Clinical research has suggested that statins may have benefit in inflammatory bowel disease. In this article, we review the effect of statins on the immune system and gastrointestinal tract, highlighting the potential for novel therapeutic applications in inflammatory bowel disease.

Lipids, blood pressure and kidney update 2014

This paper is an effort to review all the most important studies and guidelines in the topics of lipid, blood pressure and kidney published in 2014. Irrespective of advances, the options for improving simultaneous hypercholesterolemia and hypertension management (as well as its complication - chronic kidney disease) remain a problem. Recommending hypolidemic, hypotensive and kidney disease drugs to obtain therapy targets in cardiovascular, diabetic, elderly and kidney disease (=high risk) patients might strengthen risk factor control, improve compliance and the therapy efficacy, and in the consequence reduce the risk of cardiovascular events and mortality rate. That is why the authors have decided to summary and discuss the recent scientific achievements in the field of lipid, blood pressure and kidney.

Mismatch repair system in endometriotic tissue and eutopic endometrium of unaffected women

OBJECTIVE

To test the immunohistochemical staining pattern of some mismatch repair (MMR) system proteins in endometriotic tissue (ET) and eutopic endometrium.

METHODS

This was a retrospective study conducted at the Pathology and Obstetrics and Gynecology Departments of the Udine University Hospital. We analyzed 528 samples obtained from 246 patients affected by endometriosis and 71 samples from 71 patients with normal endometrium. A tissue microarray model was used to analyze the immunohistochemical expression of MMR system proteins.

RESULTS

Significant loss of MMR proteins was found in the stromal component of ETs. We found MSH2 to be expressed at a higher level than any other MMR system proteins in eutopic endometrium and ETs, to be significantly correlated to Ki-67 expression in both stromal and glandular components of ETs, and to be expressed at a significantly higher level in ETs than in eutopic endometrium. When considering the subgroup of endometriosis with high recurrence rate and glandular cytoplasmic staining for aurora A kinase, we found MMR proteins expressed at a significantly higher level in these ETs than in other ETs and eutopic endometrium of unaffected women.

CONCLUSIONS

We found significant loss of MMR proteins (known to be associated with microsatellite instability) in the stromal component of ETs. The group of ETs with glandular cytoplasmic staining for aurora A kinase had higher MMR protein expression, suggesting an increased activity of this system. Our result suggests a novel role of increased MSH2 expression in cellular proliferation of endometriosis.

Vascular cell adhesion molecule-1 expression in human intestinal microvascular endothelial cells is regulated by PI 3-kinase/Akt/MAPK/NF-kappaB: inhibitory role of curcumin

Endothelial activation and surface expression of cell adhesion molecules (CAMs) is critical for binding and recruitment of circulating leukocytes in tissues during the inflammatory response. Endothelial CAM expression plays a critical role in the intestinal microvasculature in inflammatory bowel disease (IBD), as blockade of leukocyte alpha4-integrin binding by gut endothelial CAM ligands has therapeutic benefit in IBD. Mechanisms underlying expression of vascular cell adhesion molecule (VCAM)-1, a ligand for alpha4-integrin in primary cultures of human intestinal microvascular endothelial cells (HIMEC) has not been defined. We investigated the effect of curcumin, phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B (Akt), and mitogen-activated protein kinase (MAPK) inhibitors on VCAM-1 expression and function in HIMEC. CAM expression was assessed and HIMEC-leukocyte adhesion was visualized under static and flow conditions. Western blotting and in vitro kinase assays were used to assess Akt and MAPK activation. Nuclear factor-kappaB (NF-kappaB) activation and nuclear translocation of its p65 subunit were determined. Tumor necrosis factor (TNF)-alpha/lipopolysaccharide (LPS)-induced VCAM-1 expression in HIMEC was suppressed by Akt small-interfering RNA, curcumin, and inhibitors of NF-kappaB (SN-50), p38 MAPK (SB-203580) and PI 3-kinase/Akt (LY-294002). VCAM-1 induction was partially suppressed by p44/42 MAPK (PD-098059) but unaffected by c-Jun NH2-terminal kinase (SP-600125) inhibition. Curcumin inhibited Akt/MAPK/NF-kappaB activity and prevented nuclear translocation of the p65 NF-kappaB subunit following TNF-alpha/LPS. At physiological shear stress, curcumin attenuated leukocyte adhesion to TNF-alpha/LPS-activated HIMEC monolayers. In conclusion, curcumin inhibited the expression of VCAM-1 in HIMECs through blockade of Akt, p38 MAPK, and NF-kappaB. Curcumin may represent a novel therapeutic agent targeting endothelial activation in IBD.