Gastric stem cells promote inflammation and gland remodeling in response to Helicobacter pylori via Rspo3-Lgr4 axis.

Helicobacter pylori is a pathogen that colonizes the stomach and causes chronic gastritis. Helicobacter pylori can colonize deep inside gastric glands, triggering increased R-spondin 3 (Rspo3) signaling. This causes an expansion of the "gland base module," which consists of self-renewing stem cells and antimicrobial secretory cells and results in gland hyperplasia. The contribution of Rspo3 receptors Lgr4 and Lgr5 is not well explored. Here, we identified that Lgr4 regulates Lgr5 expression and is required for H. pylori-induced hyperplasia and inflammation, while Lgr5 alone is not. Using conditional knockout mice, we reveal that R-spondin signaling via Lgr4 drives proliferation of stem cells and also induces NF-κB activity in the proliferative stem cells. Upon exposure to H. pylori, the Lgr4-driven NF-κB activation is responsible for the expansion of the gland base module and simultaneously enables chemokine expression in stem cells, resulting in gland hyperplasia and neutrophil recruitment. This demonstrates a connection between R-spondin-Lgr and NF-κB signaling that links epithelial stem cell behavior and inflammatory responses to gland-invading H. pylori.

Gastric Stem Cell Biology and Helicobacter pylori Infection.

Helicobacter pylori colonizes the human gastric mucosa and persists lifelong. An interactive network between the bacteria and host cells shapes a unique microbial niche within gastric glands that alters epithelial behavior, leading to pathologies such as chronic gastritis and eventually gastric cancer. Gland colonization by the bacterium initiates aberrant trajectories by inducing long-term inflammatory and regenerative gland responses, which involve various specialized epithelial and stromal cells. Recent studies using cell lineage tracing, organoids and scRNA-seq techniques have significantly advanced our knowledge of the molecular "identity" of epithelial and stromal cell subtypes during normal homeostasis and upon infection, and revealed the principles that underly stem cell (niche) behavior under homeostatic conditions as well as upon H. pylori infection. The activation of long-lived stem cells deep in the gastric glands has emerged as a key prerequisite of H. pylori-associated gastric site-specific pathologies such as hyperplasia in the antrum, and atrophy or metaplasia in the corpus, that are considered premalignant lesions. In addition to altering the behaviour of bona fide stem cells, injury-driven de-differentiation and trans-differentation programs, such as "paligenosis", subsequently allow highly specialized secretory cells to re-acquire stem cell functions, driving gland regeneration. This plastic regenerative capacity of gastric glands is required to maintain homeostasis and repair mucosal injuries. However, these processes are co-opted in the context of stepwise malignant transformation in chronic H. pylori infection, causing the emergence, selection and expansion of cancer-promoting stem cells.

Recent Advances and the Potential for Clinical Use of Autofluorescence Detection of Extra-Ophthalmic Tissues.

The autofluorescence (AF) characteristics of endogenous fluorophores allow the label-free assessment and visualization of cells and tissues of the human body. While AF imaging (AFI) is well-established in ophthalmology, its clinical applications are steadily expanding to other disciplines. This review summarizes clinical advances of AF techniques published during the past decade. A systematic search of the MEDLINE database and Cochrane Library databases was performed to identify clinical AF studies in extra-ophthalmic tissues. In total, 1097 articles were identified, of which 113 from internal medicine, surgery, oral medicine, and dermatology were reviewed. While comparable technological standards exist in diabetology and cardiology, in all other disciplines, comparability between studies is limited due to the number of differing AF techniques and non-standardized imaging and data analysis. Clear evidence was found for skin AF as a surrogate for blood glucose homeostasis or cardiovascular risk grading. In thyroid surgery, foremost, less experienced surgeons may benefit from the AF-guided intraoperative separation of parathyroid from thyroid tissue. There is a growing interest in AF techniques in clinical disciplines, and promising advances have been made during the past decade. However, further research and development are mandatory to overcome the existing limitations and to maximize the clinical benefits.

Hepatic CYP1A2 activity in liver tumors and the implications for preoperative volume-function analysis.

Dynamic liver function assessment by the [13C]methacetin maximal liver function capacity (LiMAx) test reflects the overall hepatic cytochrome P-450 (CYP) 1A2 activity. One proven strategy for preoperative risk assessment in liver surgery includes the combined assessment of the dynamic liver function by the LiMAx test, the volumetric analysis of the liver, and calculation of future liver remnant function. This so-called volume-function analysis assumes that the remaining CYP1A2 activity in any tumor lesion is zero. The here presented study aims to assess the remaining CYP1A2 activities in different hepatic tumor lesions and its consequences for the preoperative volume-function analysis in patients undergoing liver surgery. The CYP1A2 activity analysis of neoplastic lesions and adjacent nontumor liver tissue from resected tumor specimens revealed a significantly higher CYP1A2 activity (median, interquartile range) in nontumor tissues (35.5, 15.9-54.4 µU/mg) compared with hepatocellular adenomas (7.35, 1.2-32.5 µU/mg), hepatocellular carcinomas (0.18, 0.0-2.0 µU/mg), or colorectal liver metastasis (0.17, 0.0-2.1 µU/mg). In nontumor liver tissue, a gradual decline in CYP1A2 activity with exacerbating fibrosis was observed. The CYP1A2 activity differences were also reflected in CYP1A2 protein signals in the assessed hepatic tissues. Volume-function analysis showed a minimal deviation compared with the current standard calculation for hepatocellular carcinomas or colorectal liver metastasis (<1% difference), whereas a difference of 11.9% was observed for hepatocellular adenomas. These findings are important for a refined preoperative volume-function analysis and improved surgical risk assessment in hepatocellular adenoma cases with low LiMAx values. NEW & NOTEWORTHY The cytochrome P-450 (CYP) 1A2-dependent maximal liver function capacity test reflects the overall functional capacity of the liver. To which extent hepatocellular tumors harbor CYP1A2 activity and thus contribute to the maximal liver function capacity test outcome is unknown. We here show that hepatocellular adenomas but not hepatocellular carcinomas or colorectal liver metastasis contain significant residual CYP1A2 activity. These findings are important for an improved preoperative volume-function analysis and an accurate surgical risk assessment in hepatocellular adenoma cases.

Association of Helicobacter pylori Positivity With Risk of Disease and Mortality.

INTRODUCTION: Helicobacter pylori colonizes the human stomach. Infection causes chronic gastritis and increases the risk of gastroduodenal ulcer and gastric cancer. Its chronic colonization in the stomach triggers aberrant epithelial and inflammatory signals that are also associated with systemic alterations. METHODS: Using a PheWAS analysis in more than 8,000 participants in the community-based UK Biobank, we explored the association of H. pylori positivity with gastric and extragastric disease and mortality in a European country. RESULTS: Along with well-established gastric diseases, we dominantly found overrepresented cardiovascular, respiratory, and metabolic disorders. Using multivariate analysis, the overall mortality of H. pylori -positive participants was not altered, while the respiratory and Coronovirus 2019-associated mortality increased. Lipidomic analysis for H. pylori -positive participants revealed a dyslipidemic profile with reduced high-density lipoprotein cholesterol and omega-3 fatty acids, which may represent a causative link between infection, systemic inflammation, and disease. DISCUSSION: Our study of H. pylori positivity demonstrates that it plays an organ- and disease entity-specific role in the development of human disease and highlights the importance of further research into the systemic effects of H. pylori infection.

R-spondin/YAP axis promotes gastric oxyntic gland regeneration and Helicobacter pylori-associated metaplasia in mice.

The stomach corpus epithelium is organized into anatomical units that consist of glands and pits. Mechanisms that control the cellular organization of corpus glands and enable their recovery upon injury are not well understood. R-spondin 3 (RSPO3) is a WNT-signaling enhancer that regulates stem cell behavior in different organs. Here, we investigated the function of RSPO3 in the corpus during homeostasis, upon chief and/or parietal cell loss, and during chronic Helicobacter pylori infection. Using organoid culture and conditional mouse models, we demonstrate that RSPO3 is a critical driver of secretory cell differentiation in the corpus gland toward parietal and chief cells, while its absence promoted pit cell differentiation. Acute loss of chief and parietal cells induced by high dose tamoxifen - or merely the depletion of LGR5+ chief cells - caused an upregulation of RSPO3 expression, which was required for the initiation of a coordinated regenerative response via the activation of yes-associated protein (YAP) signaling. This response enabled a rapid recovery of the injured secretory gland cells. However, in the context of chronic H. pylori infection, the R-spondin-driven regeneration was maintained long term, promoting severe glandular hyperproliferation and the development of premalignant metaplasia.

Responses of gastric epithelial stem cells and their niche to Helicobacter pylori infection.

Helicobacter pylori (H. pylori) are gram-negative bacteria that are able to colonize and persist in the stomach. Gastric cancer is tightly linked to chronic infection with this bacterium. Research over the last decades has illuminated the molecular interactions between H. pylori and host cells. It is now well established that H. pylori have multiple sophisticated means to adhere to epithelial cells and to manipulate their behavior. This interaction with the epithelium can lead to altered cell signaling, DNA damage and aberrant epithelial immunity. H. pylori are known to colonize the mucus layer of the stomach and surface epithelial cells. In addition, it has recently become clear that they can also penetrate the glands and directly interact with specialized epithelial cells deep in the glands. Understanding the biogeography of infection is important because gastric epithelial glands are composed of various types of short-lived differentiated cells that are constantly regenerated by a limited pool of long-lived stem cells located in base of gastric glands. Recent advances in gastric stem cell research not only led to identification of stem cell populations using specific markers but has also uncovered specific regulatory pathways and principles that govern gastric stem cell behavior and regeneration. Particularly, the stem cell state is largely dependent on signals from the niche cells that surround the stem cell compartment. The subpopulation of H. pylori that colonizes in the stem cell compartment triggers specific inflammatory responses and drives epithelial pathology. Colonization of gastric glands induces responses of the stem cell niche, simultaneously enhancing the cell turnover kinetics and driving the formation of antimicrobial cells in the gland base. These data reveal the high plasticity of the epithelium and its ability to adapt to the environment, which is necessary to regenerate and counterbalance infection, but simultaneously lays the grounds for development of gastric pathology and carcinogenesis.

Erratum to "Expression Analysis of Fibronectin Type III Domain-Containing (FNDC) Genes in Inflammatory Bowel Disease and Colorectal Cancer".

[This corrects the article DOI: 10.1155/2019/3784172.].

Expression Analysis of Fibronectin Type III Domain-Containing (FNDC) Genes in Inflammatory Bowel Disease and Colorectal Cancer.

BACKGROUND: Fibronectin type III domain-containing (FNDC) proteins fulfill manifold functions in tissue development and regulation of cellular metabolism. FNDC4 was described as anti-inflammatory factor, upregulated in inflammatory bowel disease (IBD). FNDC signaling includes direct cell-cell interaction as well as release of bioactive peptides, like shown for FNDC4 or FNDC5. The G-protein-coupled receptor 116 (GPR116) was found as a putative FNDC4 receptor. We here aim to comprehensively analyze the mRNA expression of FNDC1, FNDC3A, FNDC3B, FNDC4, FNDC5, and GPR116 in nonaffected and affected mucosal samples of patients with IBD or colorectal cancer (CRC). METHODS: Mucosa samples were obtained from 30 patients undergoing diagnostic colonoscopy or from surgical resection of IBD or CRC. Gene expression was determined by quantitative real-time PCR. In addition, FNDC expression data from publicly available Gene Expression Omnibus (GEO) data sets (GDS4296, GDS4515, and GDS5232) were analyzed. RESULTS: Basal mucosal expression revealed higher expression of FNDC3A and FNDC5 in the ileum compared to colonic segments. FNDC1 and FNDC4 were significantly upregulated in IBD. None of the investigated FNDCs was differentially expressed in CRC, just FNDC3A trended to be upregulated. The GEO data set analysis revealed significantly downregulated FNDC4 and upregulated GPR116 in microsatellite unstable (MSI) CRCs. The expression of FNDCs and GPR116 was independent of age and sex. CONCLUSIONS: FNDC1 and FNDC4 may play a relevant role in the pathobiology of IBD, but none of the investigated FNDCs is regulated in CRC. GPR116 may be upregulated in advanced or MSI CRC. Further studies should validate the altered FNDC expression results on protein levels and examine the corresponding functional consequences.

Identification of serological markers for pre- and postoperative fasting periods.

BACKGROUND & AIMS: Prolonged preoperative fasting periods lead to catabolic states and decelerate recovery after surgery. Valid plasma markers reflecting the patients' metabolic state may improve tailored nutrition support before surgery. Within this study, we sought to advance the knowledge on fasting time-sensitive plasma markers that allow the metabolic characterisation of surgical patients for an optimised preoperative metabolic preparation. METHODS: Patients scheduled for elective surgery of the upper (n = 23) or lower (n = 27) gastrointestinal tract participated in a prospective observational study. Patients' charateristics and nutritional status were recorded and blood samples were drawn on the day of admission. Further blood samples were collected before skin incision of the surgical procedure, on postoperative day 3 and on the day of discharge. Values of clinical chemistry, electrolytes, hemograms and plasma amino acids were determined and correlated with fasting times. RESULTS: Preoperative fasting times were positively correlated with plasma levels of valine, leucine, serine, α-amino butyric acid, free fatty acids, 3-hydroxy butyric acid and significantly negative correlated with chloride and glutamic acid. Postoperative fasting times were correlated with erythrocytes, leukocytes and plasma levels of albumin, CRP, HDL, asparagine and 3-methylhistidine. The multivariate regression analysis revealed glutamic acid and valine as significant independent predictors of preoperative fasting periods. The regression model showed best performance (sensitivity of 90.91% and specificity of 92.31%) to detect patients fasted for ≥20 h. CONCLUSION: Valine and glutamic acid appear as independent metabolic markers for accurate prediction of prolonged fasting periods, independent of the overall nutritional status, age or BMI of patients.

Autofluorescence: A potential pitfall in immunofluorescence-based inflammation grading.

Immunofluorescence (IF) staining of paraffin-embedded tissues is a frequently used method to answer research questions or even detect the abundance of a certain protein for diagnostic use. However, the signal originating from specific antibody-staining might be distorted by autofluorescence (AF) of the assessed tissue. Although the AF phenomenon is well known, its presence is often neglected by insufficient staining controls. In this study, we describe the existence of cellular AF in paraffin-embedded healthy and inflamed human and murine colonic tissues and present ways to reduce AF. The AF signal is detectable at emission spectra from 425 nm-738 nm, upon excitation from 403.6-638.7 nm and appears more pronounced in inflamed tissues. Most signals are located subepithelially in the tissue and in blood vessels. Previous studies have shown that the AF signals are caused by lipofuscin, which accumulates in lamina propria immune cells. In murine small intestine AF signals are present in granules in the Paneth cell zone. For alleviation of the AF signal, sudan black b (SBB) or copper sulfate was used. Incubation of the tissue slices with either one of the substances reduced AF. In conclusion, AF appears as an intrinsic biomarker for colonic inflammation. The dominant existence of AF in immune cells of IBD tissue elucidates the importance of negative controls and the limitation of IF staining for potential diagnostic purposes.