Branching crypts in inflammatory bowel disease revisited

Architectural crypt distortions in ulcerative colitis: Time for reappraisal

Chronic mucosal inflammation and architectural crypt distortions (ACD) are essential for the histologic diagnosis of ulcerative colitis (UC). ACD in UC has been defined as irregularly arranged, dilated, branched, and shortened crypts with inequality of inter-crypt distance. However, neither the diagnostic sections' crypt phenotype nor the cutting mode have been considered. In this regard, previous studies showed that most diagnostic biopsies in UC are fortuitously crosscut at laboratories. In this communication, we review the crypt phenotypes that are included in the ACD in UC notion: crypts in asymmetric branching, crypt rings in tandem, crypts with lateral buds, face-to-face "kissing crypts," crypts-in-crypts, laterally orientated crypts in anthemia fold domains, and crypts with irregular shape and size in innominate groves domains. The awareness that disparate crypt phenotypes may participate in the ACD notion may open new vistas in the interpretation of crypt distortions in crosscut diagnostic sections in UC. The present findings will permit endoscopists and clinicians to better understand the narrative of ACD in the pathological diagnosis.

Marine Algae and Deriving Biomolecules for the Management of Inflammatory Bowel Diseases: Potential Clinical Therapeutics to Decrease Gut Inflammatory and Oxidative Stress Markers?

The term "inflammatory bowel disease" (IBD) describes a class of relapse-remitting conditions that affect the gastrointestinal (GI) tract. Among these, Crohn's disease (CD) and ulcerative colitis (UC) are two of the most globally prevalent and debilitating conditions. Several articles have brought attention to the significant role that inflammation and oxidative stress cooperatively play in the development of IBD, offering a different viewpoint both on its etiopathogenesis and on strategies for the effective treatment of these conditions. Marine ecosystems may be a significant source of physiologically active substances, supporting the search for new potential clinical therapeutics. Based on this evidence, this review aims to comprehensively evaluate the activity of marine algae and deriving biomolecules in decreasing pathological features of CD and UC. To match this purpose, a deep search of the literature on PubMed (MEDLINE) and Google Scholar was performed to highlight primary biological mechanisms, the modulation of inflammatory and oxidative stress biochemical parameters, and potential clinical benefits deriving from marine species. From our findings, both macroalgae and microalgae have shown potential as therapeutic solutions for IBD due to their bioactive compounds and their anti-inflammatory and antioxidant activities which are capable of modulating markers such as cytokines, the NF-κB pathway, reactive oxidative and nitrosative species (ROS and RNS), trefoil factor 3 (TFF3), lactoferrin, SIRT1, etc. However, while we found promising preclinical evidence, more extensive and long-term clinical studies are necessary to establish the efficacy and safety of marine algae for IBD treatment.

Disruption of epithelium integrity by inflammation-associated fibroblasts through prostaglandin signaling

Inflammation-associated fibroblasts (IAFs) are associated with progression and drug resistance of chronic inflammatory diseases such as inflammatory bowel disease (IBD), but their direct impact on epithelial cells is unknown. Here, we developed an in vitro model whereby human colon fibroblasts are induced by specific cytokines and recapitulate key features of IAFs in vivo. When cocultured with patient-derived colon organoids (colonoids), IAFs induced rapid colonoid expansion and barrier disruption due to swelling and rupture of individual epithelial cells. Colonoids cocultured with IAFs also show increased DNA damage, mitotic errors, and proliferation arrest. These IAF-induced epithelial defects are mediated by a paracrine pathway involving prostaglandin E2 and its receptor EP4, leading to protein kinase A -dependent activation of the cystic fibrosis transmembrane conductance regulator. EP4-specific chemical inhibitors effectively prevented IAF-induced colonoid swelling and restored normal proliferation and genome stability. These findings reveal a mechanism by which IAFs could promote and perpetuate IBD and suggest a therapeutic avenue to mitigate inflammation-associated epithelial injury.

The Histology-Driven Differential Diagnosis in Bowel Inflammatory Conditions Is Not All That Obvious: Evidence from a Survey Based on Digital Slides

(1) Background: when the pathologist faces histologic slides from colonoscopies in daily practice, given the large number of entities and etiologies under inflammatory bowel conditions, in-depth definition of the histological spectrum and the recommendations of current guidelines are often not enough to conclusively define a diagnostic framework. Histological patterns should be organized hierarchically in flowcharts that consider the correlation with clinical data. We conducted an online survey asking a group of gastroenteropathologists to apply a pattern classification based on the most significant lesions in colitis differential diagnosis: crypt distortion and activity. (2) Methods: digital slides from 20 endoscopy samples were analyzed by twenty pathologists and classified according to the occurrence of crypt distortion (nondestructive-destructive colitis) and subsequently to the evidence of activity (ND1-2-3, D1-2). (3) Results: in 8 out of 20 (40%) cases, the participants reached a full agreement regarding the evaluation of crypt distortion (5 cases: nondestructive colitis; 3 cases: destructive colitis). The calculated agreement was k = 0.432. In the second-level quiz (ND1-2-3 and D1-2), full agreement between participants was achieved for 7 of the 28 (25%) possible classifications, with k = 0.229. (4) Conclusions: The findings from this survey are indicative of an unexpectedly low consensus, even among dedicated pathologists, about the recognition of histological changes that are commonly considered critical lesions in the histologic identification of bowel non-neoplastic diseases. In our opinion, these divergences imply a significant risk of misdiagnosis of bowel inflammatory conditions, hampering the usefulness of histological assessment.

A pilot genome-wide association study meta-analysis of gastroparesis

BACKGROUND

Gastroparesis (GP) is characterized by delayed gastric emptying in the absence of mechanical obstruction.

OBJECTIVE

Genetic predisposition may play a role; however, investigation at the genome-wide level has not been performed.

METHODS

We carried out a genome-wide association study (GWAS) meta-analysis on (i) 478 GP patients from the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Clinical Research Consortium (GpCRC) compared to 9931 population-based controls from the University of Michigan Health and Retirement Study; and (ii) 402 GP cases compared to 48,340 non-gastroparesis controls from the Michigan Genomics Initiative. Associations for 5,811,784 high-quality SNPs were tested on a total of 880 GP patients and 58,271 controls, using logistic mixed models adjusted for age, sex, and principal components. Gene mapping was obtained based on genomic position and expression quantitative trait loci, and a gene-set network enrichment analysis was performed. Genetic associations with clinical data were tested in GpCRC patients. Protein expression of selected candidate genes was determined in full thickness gastric biopsies from GpCRC patients and controls.

RESULTS

While no SNP associations were detected at strict significance (p ≤ 5 × 10-8 ), nine independent genomic loci were associated at suggestive significance (p ≤ 1 × 10-5 ), with the strongest signal (rs9273363, odds ratio = 1.4, p = 1 × 10-7 ) mapped to the human leukocyte antigen region. Computational annotation of suggestive risk loci identified 14 protein-coding candidate genes. Gene-set network enrichment analysis revealed pathways potentially involved in immune and motor dysregulation (pFDR ≤ 0.05). The GP risk allele rs6984536A (Peroxidasin-Like; PXDNL) was associated with increased abdominal pain severity scores (Beta = 0.13, p = 0.03). Gastric muscularis expression of PXDNL also positively correlated with abdominal pain in GP patients (r = 0.8, p = 0.02). Dickkopf WNT Signaling Pathway Inhibitor 1 showed decreased expression in diabetic GP patients (p = 0.005 vs. controls).

CONCLUSION

We report preliminary GWAS findings for GP, which highlight candidate genes and pathways related to immune and sensory-motor dysregulation. Larger studies are needed to validate and expand these findings in independent datasets.

Disruption of Epithelium Integrity by Inflammation-Associated Fibroblasts through Prostaglandin Signaling: IAFs disrupt colon epithelium via PGE2-EP4

Inflammation-associated fibroblasts (IAFs) are associated with the progression and drug resistance of chronic inflammatory diseases such as inflammatory bowel disease (IBD), but their direct impact on epithelial function and architecture is unknown. In this study, we developed an in vitro model whereby human colon fibroblasts are induced to become IAFs by specific cytokines and recapitulate key features of IAFs in vivo. When co-cultured with patient-derived colon organoids (colonoids), IAFs induced rapid colonoid swelling and barrier disruption due to swelling and rupture of individual epithelial cells. Epithelial cells co-cultured with IAFs also exhibit increased DNA damage, mitotic errors, and proliferation arrest. These IAF-induced epithelial defects are mediated through a paracrine pathway involving prostaglandin E2 (PGE2) and the PGE2 receptor EP4, leading to PKA-dependent activation of the CFTR chloride channel. Importantly, EP4-specific chemical inhibitors effectively prevented colonoid swelling and restored normal proliferation and genome stability of IAF-exposed epithelial cells. These findings reveal a mechanism by which IAFs could promote and perpetuate IBD and suggest a potential treatment to mitigate inflammation-associated epithelial injury.

Keratin 7 expression in different anatomical parts of colonic epithelium in inflammatory bowel diseases and its prognostic value: a 3-year follow-up study

The diagnosis of inflammatory bowel diseases (IBD) may be challenging and their clinical course, characterized by relapses and spontaneous or drug-induced remissions, is difficult to predict. Novel prognostic biomarkers are needed. Keratin 7 (K7) is a cytoskeletal intermediate filament protein which is not normally expressed in the colonic epithelium. It was recently shown that K7 expression in the colonic epithelium is associated with ulcerative colitis and Crohn's disease, the two main subtypes of IBD. Here we investigated IBD associated K7 neo-expression in different regions of colon and terminal ileum. The correlation of the K7 expression with the inflammatory activity of the epithelium was analyzed in each region. The prognostic value of K7 was estimated by comparing the clinical disease activity after 3 years with the K7 expression at the time of enrollment. Our data shows that the level of K7 expression in inflamed epithelium varies depending on the anatomical region and it is the most pronounced in ascending and descending colon, but it did not predict the severity of IBD for the following 3 years. These results warrant future studies focusing on the biological role of K7 in colon and its utilization as potential IBD biomarker.

The frequency of dysplastic branching crypts in colorectal polypoid tubular adenomas

Dysplastic crypt branching (DCB) was recently found in ulcerative colitis-associated dysplasia. The aim was to assess the frequency and the branching phenotype of DCB in polypoid colorectal tubular adenomas (TA). A total of 3956 DCB were found in the 139 TA: 98% were in asymmetric branching (DCAB) and the remaining 2% in symmetric branching (DCSB). A linear correlation was found between DCB frequency and the increasing digital size in TA (p < .05). Using a digital ruler, adenomas were divided into small TA (<5 mm) and larger TA (≥5 mm). The difference between the frequency of DCB in small TA (n = 75) vs. larger TA (n = 64), was significant (p < .05). DCB frequency was not influenced by age, gender or TA localization. In the normal colorectal mucosa (≈2 m² ), only occasional CSB is found and no CAB. And yet, multiple DCB (mean 16.7 DCB), mostly DCAB, was found in small TA, occupying <5 mm of the mucosal area. In larger TA, as many as 42.1 DCB (mean), mostly DCAB, occurred in merely 7.8 mm (mean) of the colon mucosa. Thus it is suggested that DCB is a standard histologic element of TA. The natural expansion of the adenomatous tissue in larger TA appears to be follow on from newly produced, mostly DCAB, by DCSB and by the accumulation of their dysplastic offspring's progenies. The findings strongly suggest that DCB is a central microstructure in the histological events unfolding in polypoid colorectal TA.

Regulation and functions of cell division in the intestinal tissue

In multicellular organisms, epithelial cells are key elements of tissue organization. In developing epithelial tissues, cellular proliferation and differentiation are under the tight regulation of morphogenetic programs to ensure correct organ formation and functioning. In these processes, proliferation rates and division orientation regulate the speed, timing and direction of tissue expansion but also its proper patterning. Moreover, tissue homeostasis relies on spatio-temporal modulations of daughter cell behavior and arrangement. These aspects are particularly crucial in the intestine, which is one of the most proliferative tissues in adults, making it a very attractive adult organ system to study the role of cell division on epithelial morphogenesis and organ function. Although epithelial cell division has been the subject of intense research for many years in multiple models, it still remains in its infancy in the context of the intestinal tissue. In this review, we focus on the current knowledge on cell division and regulatory mechanisms at play in the intestinal epithelial tissue, as well as their importance in developmental biology and physiopathology.

Antimetabolite Drugs Exhibit Distinctive Immunomodulatory Mechanisms and Effects on the Intestinal Microbiota in Experimental Autoimmune Uveitis

Purpose

The purpose of this study was to investigate the effect of antimetabolite drugs on T-cell responses and intestinal microbial composition in autoimmune uveitis.

Methods

Experimental autoimmune uveitis (EAU) was induced in C57BL/6J mice treated with 0.00625 mg/mL methotrexate (MTX) or 0.625 mg/mL mycophenolate mofetil (MMF) in drinking water for 4 weeks prior to immunization and 2 weeks thereafter. The effector T cell (Teff) and regulatory T cell (Treg) populations were identified using flow cytometry. The 16S rRNA gene sequencing was applied for gut microbiome characterization. DESeq2 analysis was used to discriminate relative abundances of taxa and PLS-DA to integrate cytometric and microbiome data between groups.

Results

Both MTX and MMF abrogated uveitis in EAU without clinical signs of toxicity as compared to water-fed controls. MTX reduced Teff and Treg expansion in peripheral tissues and eyes. MTX decreased alpha diversity, increased Akkermansia, and reduced Lachnoclostridium abundances. Conversely, MMF enhanced Tregs in the mesenteric lymph node and the eyes. In parallel, MMF increased the gut alpha diversity, including an increased abundance of Lachnospiraceae NK4A136 group and a decreased abundance of Lachnospiraceae UCG-001. A significant congruent correlation among intestinal microbial changes, T-cell responses, and clinical scores was observed for both antimetabolites.

Conclusions

Although MTX and MMF both abrogated uveitis in EAU, they showed different effects on T-cell subsets and the intestinal bacterial composition. This work indicates unique immunomodulation by each drug and is the first to demonstrate potential microbiota-related mechanisms.

Objetivo

Investigar el efecto de los fármacos antimetabolitos sobre las respuestas de células T y la composición microbiana intestinal en la uveítis autoinmune.

Métodos

Se indujo uveítis autoinmune experimental (UAE) en ratones C57BL/6J tratados con 0.00625 mg/ml de metotrexato (MTX) o 0.625 mg/ml de micofenolato mofetilo (MFM) en agua de bebida durante 4 semanas antes de la inmunización y 2 semanas después. Las poblaciones de células T efectoras (Tef) y reguladoras (Treg) se identificaron por citometría de flujo. La caracterización del microbioma intestinal se realizó mediante secuenciación del gen 16S ARNr. El análisis discriminante de abundancias relativas en los taxones se llevó a cabo por DESeq2 y se usó un análisis PLS-DA para integrar los datos microbianos y citométricos entre grupos.

Resultados

MTX y MFM inhibieron la UAE sin signos clínicos de toxicidad comparado con los controles. MTX disminuyó la expansión de Tef y Treg en los tejidos periféricos y oculares. MTX redujo la alfa diversidad, incrementando la abundancia de Akkermansia, y reduciendo la de Lachnoclostridium. En cambio, MFM aumentó los Tregs en el ganglio mesentérico y en los ojos. Paralelamente, MFM aumentó la alfa diversidad, incluyendo un aumento de la abundancia del grupo Lachnospiraceae NK4A136 y un descenso de la de Lachnospiraceae UCG-001. Se observó una correlación congruente significativa, para ambos fármacos, entre los cambios en el microbioma, las respuestas de células T y los grados clínicos de uveítis.

Conclusiones

Aunque ambos, MTX y MFM, suprimieron la UAE, mostraron efectos diferentes sobre los subtipos de células T y sobre la composición del microbioma. Este estudio indica un efecto inmunomodulador único para cada fármaco y es el primero en demostrar potenciales mecanismos relacionados con el microbioma.