Loss of Mucosal p32/gC1qR/HABP1 Triggers Energy Deficiency and Impairs Goblet Cell Differentiation in Ulcerative Colitis

Notoginsenoside R1 promotes Lgr5+ stem cell and epithelium renovation in colitis mice via activating Wnt/β-Catenin signaling

Inflammatory bowel disease (IBD) is characterized by persistent damage to the intestinal barrier and excessive inflammation, leading to increased intestinal permeability. Current treatments of IBD primarily address inflammation, neglecting epithelial repair. Our previous study has reported the therapeutic potential of notoginsenoside R1 (NGR1), a characteristic saponin from the root of Panax notoginseng, in alleviating acute colitis by reducing mucosal inflammation. In this study we investigated the reparative effects of NGR1 on mucosal barrier damage after the acute injury stage of DSS exposure. DSS-induced colitis mice were orally treated with NGR1 (25, 50, 125 mg·kg-1·d-1) for 10 days. Body weight and rectal bleeding were daily monitored throughout the experiment, then mice were euthanized, and the colon was collected for analysis. We showed that NGR1 administration dose-dependently ameliorated mucosal inflammation and enhanced epithelial repair evidenced by increased tight junction proteins, mucus production and reduced permeability in colitis mice. We then performed transcriptomic analysis on rectal tissue using RNA-sequencing, and found NGR1 administration stimulated the proliferation of intestinal crypt cells and facilitated the repair of epithelial injury; NGR1 upregulated ISC marker Lgr5, the genes for differentiation of intestinal stem cells (ISCs), as well as BrdU incorporation in crypts of colitis mice. In NCM460 human intestinal epithelial cells in vitro, treatment with NGR1 (100 μM) promoted wound healing and reduced cell apoptosis. NGR1 (100 μM) also increased Lgr5+ cells and budding rates in a 3D intestinal organoid model. We demonstrated that NGR1 promoted ISC proliferation and differentiation through activation of the Wnt signaling pathway. Co-treatment with Wnt inhibitor ICG-001 partially counteracted the effects of NGR1 on crypt Lgr5+ ISCs, organoid budding rates, and overall mice colitis improvement. These results suggest that NGR1 alleviates DSS-induced colitis in mice by promoting the regeneration of Lgr5+ stem cells and intestinal reconstruction, at least partially via activation of the Wnt/β-Catenin signaling pathway. Schematic diagram of the mechanism of NGR1 in alleviating colitis. DSS caused widespread mucosal inflammation epithelial injury. This was manifested by the decreased expression of tight junction proteins, reduced mucus production in goblet cells, and increased intestinal permeability in colitis mice. Additionally, Lgr5+ ISCs were in obviously deficiency in colitis mice, with aberrant down-regulation of the Wnt/β-Catenin signaling. However, NGR1 amplified the expression of the ISC marker Lgr5, elevated the expression of genes associated with ISC differentiation, enhanced the incorporation of BrdU in the crypt and promoted epithelial restoration to alleviate DSS-induced colitis in mice, at least partially, by activating the Wnt/β-Catenin signaling pathway.

Azathioprine promotes intestinal epithelial cell differentiation into Paneth cells and alleviates ileal Crohn's disease severity

Paneth cells (PCs), a subset of intestinal epithelial cells (IECs) found at the base of small intestinal crypts, play an essential role in maintaining intestinal homeostasis. Altered PCs function is associated with diverse intestinal pathologies, including ileal Crohn's disease (CD). CD patients with ileal involvement have been previously demonstrated to display impairment in PCs and decreased levels of anti-microbial peptides. Although the immunosuppressive drug Azathioprine (AZA) is widely used in CD therapy, the impact of AZA on IEC differentiation remains largely elusive. In the present study, we hypothesized that the orally administered drug AZA also exerts its effect through modulation of the intestinal epithelium and specifically via modulation of PC function. AZA-treated CD patients exhibited an ileal upregulation of AMPs on both mRNA and protein levels compared to non-AZA treated patients. Upon in vitro AZA stimulation, intestinal epithelial cell line MODE-K exhibited heightened expression levels of PC marker in concert with diminished cell proliferation but boosted mitochondrial OXPHOS activity. Moreover, differentiation of IECs, including PCs differentiation, was boosted in AZA-treated murine small intestinal organoids and was associated with decreased D-glucose consumption and decreased growth rates. Of note, AZA treatment strongly decreased Lgr5 mRNA expression as well as Ki67 positive cells. Further, AZA restored dysregulated PCs associated with mitochondrial dysfunction. AZA-dependent inhibition of IEC proliferation is accompanied by boosted mitochondria function and IEC differentiation into PC.

Systematic review of metabolomic alterations in ulcerative colitis: unveiling key metabolic signatures and pathways

Background

Despite numerous metabolomic studies on ulcerative colitis (UC), the results have been highly variable, making it challenging to identify key metabolic abnormalities in UC.

Objectives

This study aims to uncover key metabolites and metabolic pathways in UC by analyzing existing metabolomics data.

Design

A systematic review.

Data sources and methods

We conducted a comprehensive search in databases (PubMed, Cochrane Library, Embase, and Web of Science) and relevant study references for metabolomic research on UC up to 28 December 2022. Significant metabolite differences between UC patients and controls were identified, followed by an analysis of relevant metabolic pathways.

Results

This review incorporated 78 studies, identifying 2868 differentially expressed metabolites between UC patients and controls. The metabolites were predominantly from 'lipids and lipid-like molecules' and 'organic acids and derivatives' superclasses. We found 101 metabolites consistently altered in multiple datasets within the same sample type and 78 metabolites common across different sample types. Of these, 62 metabolites exhibited consistent regulatory trends across various datasets or sample types. Pathway analysis revealed 22 significantly altered metabolic pathways, with 6 pathways being recurrently enriched across different sample types.

Conclusion

This study elucidates key metabolic characteristics in UC, offering insights into molecular mechanisms and biomarker discovery for the disease. Future research could focus on validating these findings and exploring their clinical applications.

Leaky gut, circulating immune complexes, arthralgia, and arthritis in IBD: coincidence or inevitability?

Most host-microbiota interactions occur within the intestinal barrier, which is essential for separating the intestinal epithelium from toxins, microorganisms, and antigens in the gut lumen. Gut inflammation allows pathogenic bacteria to enter the blood stream, forming immune complexes which may deposit on organs. Despite increased circulating immune complexes (CICs) in patients with inflammatory bowel disease (IBD) and discussions among IBD experts regarding their potential pathogenic role in extra-intestinal manifestations, this phenomenon is overlooked because definitive evidence demonstrating CIC-induced extra-intestinal manifestations in IBD animal models is lacking. However, clinical observations of elevated CICs in newly diagnosed, untreated patients with IBD have reignited research into their potential pathogenic implications. Musculoskeletal symptoms are the most prevalent extra-intestinal IBD manifestations. CICs are pivotal in various arthritis forms, including reactive, rheumatoid, and Lyme arthritis and systemic lupus erythematosus. Research indicates that intestinal barrier restoration during the pre-phase of arthritis could inhibit arthritis development. In the absence of animal models supporting extra-intestinal IBD manifestations, this paper aims to comprehensively explore the relationship between CICs and arthritis onset via a multifaceted analysis to offer a fresh perspective for further investigation and provide novel insights into the interplay between CICs and arthritis development in IBD.

SLE serum induces altered goblet cell differentiation and leakiness in human intestinal organoids

Human intestinal epithelial cells are the interface between luminal content and basally residing immune cells. They form a tight monolayer that constantly secretes mucus creating a multilayered protective barrier. Alterations in this barrier can lead to increased permeability which is common in systemic lupus erythematosus (SLE) patients. However, it remains unexplored how the barrier is affected. Here, we present an in vitro model specifically designed to examine the effects of SLE on epithelial cells. We utilize human colon organoids that are stimulated with serum from SLE patients. Combining transcriptomic with functional analyses revealed that SLE serum induced an expression profile marked by a reduction of goblet cell markers and changed mucus composition. In addition, organoids exhibited imbalanced cellular composition along with enhanced permeability, altered mitochondrial function, and an interferon gene signature. Similarly, transcriptomic analysis of SLE colon biopsies revealed a downregulation of secretory markers. Our work uncovers a crucial connection between SLE and intestinal homeostasis that might be promoted in vivo through the blood, offering insights into the causal connection of barrier dysfunction and autoimmune diseases.

Unique Metabolomic and Lipidomic Profile in Serum From Patients With Crohn's Disease and Ulcerative Colitis Compared With Healthy Control Individuals

BACKGROUND

Accurate biomarkers for disease activity and progression in patients with inflammatory bowel disease (IBD) are a prerequisite for individual disease characterization and personalized therapy. We show that metabolic profiling of serum from IBD patients is a promising approach to establish biomarkers. The aim of this work was to characterize metabolomic and lipidomic serum profiles of IBD patients in order to identify metabolic fingerprints unique to the disease.

METHODS

Serum samples were obtained from 55 patients with Crohn's disease (CD), 34 patients with ulcerative colitis (UC), and 40 healthy control (HC) individuals and analyzed using proton nuclear magnetic resonance spectroscopy. Classification of patients and HC individuals was achieved by orthogonal partial least squares discriminant analysis and univariate analysis approaches. Disease activity was assessed using the Gastrointestinal Symptom Rating Scale.

RESULTS

Serum metabolome significantly differed between CD patients, UC patients, and HC individuals. The metabolomic differences of UC and CD patients compared with HC individuals were more pronounced than the differences between UC and CD patients. Differences in serum levels of pyruvic acid, histidine, and the branched-chain amino acids leucine and valine were detected. The size of low-density lipoprotein particles shifted from large to small dense particles in patients with CD. Of note, apolipoprotein A1 and A2 serum levels were decreased in CD and UC patients with higher fecal calprotectin levels. The Gastrointestinal Symptom Rating Scale is negatively associated with the concentration of apolipoprotein A2.

CONCLUSIONS

Metabolomic assessment of serum samples facilitated the differentiation of IBD patients and HC individuals. These differences were constituted by changes in amino acid and lipoprotein levels. Furthermore, disease activity in IBD patients was associated with decreased levels of the atheroprotective apolipoproteins A1 and A2.

Interaction between mitochondria and microbiota modulating cellular metabolism in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a prototypic complex disease in the gastrointestinal tract that has been increasing in incidence and prevalence in recent decades. Although the precise pathophysiology of IBD remains to be elucidated, a large body of evidence suggests the critical roles of mitochondria and intestinal microbiota in the pathogenesis of IBD. In addition to their contributions to the disease, both mitochondria and gut microbes may interact with each other and modulate disease-causing cell activities. Therefore, we hypothesize that dissecting this unique interaction may help to identify novel pathways involved in IBD, which will further contribute to discovering new therapeutic approaches to the disease. As poorly treated IBD significantly affects the quality of life of patients and is associated with risks and complications, successful treatment is crucial. In this review, we stratify previously reported experimental and clinical observations of the role of mitochondria and intestinal microbiota in IBD. Additionally, we review the intercommunication between mitochondria, and the intestinal microbiome in patients with IBD is reviewed along with the potential mediators for these interactions. We specifically focus on their roles in cellular metabolism in intestinal epithelial cells and immune cells. To this end, we propose a potential therapeutic intervention strategy for IBD.

Regulation of epithelial cell differentiation by the Ubiquitous expressed transcript isoform 1 in ulcerative colitis

BACKGROUND AND AIM

Mucosal healing has emerged as a desirable treatment goal for patients with ulcerative colitis (UC). Healing of mucosal wounds involves epithelial cell proliferation and differentiation, and Y-box transcription factor ZONAB has recently been identified as the key modulator of intestinal epithelial restitution.

METHODS

We studied the characteristics of UXT-V1 expression in UC patients using immunohistochemistry and qPCR. The functional role of UXT-V1 in the colonic epithelium was investigated using lentivirus-mediated shRNA in vitro and ex vivo. Through endogenous Co-immunoprecipitation and LC-MS/MS, we identified ZONAB as a UXT-V1-interactive protein.

RESULTS

Herein, we report that UXT-V1 promotes differentiation of intestinal epithelial cells by regulating the nuclear translocation of ZONAB. UXT-V1 was upregulated in the intestinal epithelia of UC patients compared with that of healthy controls. Knocking down UXT-V1 in NCM-460 cells led to the enrichment of pathways associated with proliferation and differentiation. Furthermore, the absence of UXT-V1 in cultured intestinal epithelial cells and colonic organoids inhibited differentiation to the goblet cell phenotype. Mechanistically, the loss of UXT-V1 in the intestinal epithelial cells allowed nuclear translocation of ZONAB, wherein it regulated the transcription of differentiation-related genes, including AML1 and KLF4.

CONCLUSION

Taken together, our study reveals a potential role of UXT-V1 in regulating epithelial cell differentiation, proving a molecular basis for mucosal healing in UC.

Natural polysaccharides protect against diet-induced obesity by improving lipid metabolism and regulating the immune system

Unhealthy dietary patterns-induced obesity and obesity-related complications pose a great threat to human health all over the world. Accumulating evidence suggests that the pathophysiology of obesity and obesity-associated metabolic disorders is closely associated with dysregulation of lipid and energy metabolism, and metabolic inflammation. In this review, three potential anti-obesity mechanisms of natural polysaccharides are introduced. Firstly, natural polysaccharides protect against diet-induced obesity directly by improving lipid and cholesterol metabolism. Since the immunity also affects lipid and energy metabolism, natural polysaccharides improve lipid and energy metabolism by regulating host immunity. Moreover, diet-induced mitochondrial dysfunction, prolonged endoplasmic reticulum stress, defective autophagy and microbial dysbiosis can disrupt lipid and/or energy metabolism in a direct and/or inflammation-induced manner. Therefore, natural polysaccharides also improve lipid and energy metabolism and suppress inflammation by alleviating mitochondrial dysfunction and endoplasmic reticulum stress, promoting autophagy and regulating gut microbiota composition. Specifically, this review comprehensively summarizes underlying anti-obesity mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates anti-obesity mechanisms of natural polysaccharides from the perspectives of their hypolipidemic, energy-regulating and immune-regulating mechanisms.

Local fat content determines global and local stiffness in livers with simple steatosis

Fat accumulation during liver steatosis precedes inflammation and fibrosis in fatty liver diseases, and is associated with disease progression. Despite a large body of evidence that liver mechanics play a major role in liver disease progression, the effect of fat accumulation by itself on liver mechanics remains unclear. Thus, we conducted ex vivo studies of liver mechanics in rodent models of simple steatosis to isolate and examine the mechanical effects of intrahepatic fat accumulation, and found that fat accumulation softens the liver. Using a novel adaptation of microindentation to permit association of local mechanics with microarchitectural features, we found evidence that the softening of fatty liver results from local softening of fatty regions rather than uniform softening of the liver. These results suggest that fat accumulation itself exerts a softening effect on liver tissue. This, along with the localized heterogeneity of softening within the liver, has implications in what mechanical mechanisms are involved in the progression of liver steatosis to more severe pathologies and disease. Finally, the ability to examine and associate local mechanics with microarchitectural features is potentially applicable to the study of the role of heterogeneous mechanical microenvironments in both other liver pathologies and other organ systems.

The role of goblet cells and mucus in intestinal homeostasis

The intestinal tract faces numerous challenges that require several layers of defence. The tight epithelium forms a physical barrier that is further protected by a mucus layer, which provides various site-specific protective functions. Mucus is produced by goblet cells, and as a result of single-cell RNA sequencing identifying novel goblet cell subpopulations, our understanding of their various contributions to intestinal homeostasis has improved. Goblet cells not only produce mucus but also are intimately linked to the immune system. Mucus and goblet cell development is tightly regulated during early life and synchronized with microbial colonization. Dysregulation of the developing mucus systems and goblet cells has been associated with infectious and inflammatory conditions and predisposition to chronic disease later in life. Dysfunctional mucus and altered goblet cell profiles are associated with inflammatory conditions in which some mucus system impairments precede inflammation, indicating a role in pathogenesis. In this Review, we present an overview of the current understanding of the role of goblet cells and the mucus layer in maintaining intestinal health during steady-state and how alterations to these systems contribute to inflammatory and infectious disease.

Role of Energy Metabolism and Mitochondrial Function in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic recurring inflammation of the intestine which can be debilitating for those with intractable disease. However, the etiopathogenesis of inflammatory bowel disorders remains to be solved. The hypothesis that mitochondrial dysfunction is a crucial factor in the disease process is being validated by an increasing number of recent studies. Thus mitochondrial alteration in conjunction with previously identified genetic predisposition, changes in the immune response, altered gut microbiota, and environmental factors (eg, diet, smoking, and lifestyle) are all posited to contribute to IBD. The implicated factors seem to affect mitochondrial function or are influenced by mitochondrial dysfunction, which explains many of the hallmarks of the disease. This review summarizes the results of studies reporting links between mitochondria and IBD that were available on PubMed through March 2021. The aim of this review is to give an overview of the current understanding of the role of mitochondria in the pathogenesis of IBD.

Intestinal mucosal barrier in functional constipation: Dose it change?

BACKGROUND

The intestinal mucosal barrier is the first line of defense against numerous harmful substances, and it contributes to the maintenance of intestinal homeostasis. Recent studies reported that structural and functional changes in the intestinal mucosal barrier were involved in the pathogenesis of several intestinal diseases. However, no study thoroughly evaluated this barrier in patients with functional constipation (FC).

AIM

To investigate the intestinal mucosal barrier in FC, including the mucus barrier, intercellular junctions, mucosal immunity and gut permeability.

METHODS

Forty FC patients who fulfilled the Rome IV criteria and 24 healthy controls were recruited in the Department of Gastroenterology of China-Japan Friendship Hospital. The colonic mucus barrier, intercellular junctions in the colonic epithelium, mucosal immune state and gut permeability in FC patients were comprehensively examined. Goblet cells were stained with Alcian Blue/Periodic acid Schiff (AB/PAS) and counted. The ultrastructure of intercellular junctional complexes was observed under an electron microscope. Occludin and zonula occludens-1 (ZO-1) in the colonic mucosa were located and quantified using immunohistochemistry and quantitative real-time polymerase chain reaction. Colonic CD3+ intraepithelial lymphocytes (IELs) and CD3+ lymphocytes in the lamina propria were identified and counted using immunofluorescence. The serum levels of D-lactic acid and zonulin were detected using enzyme-linked immunosorbent assay.

RESULTS

Compared to healthy controls, the staining of mucus secreted by goblet cells was darker in FC patients, and the number of goblet cells per upper crypt in the colonic mucosa was significantly increased in FC patients (control, 18.67 ± 2.99; FC, 22.42 ± 4.09; P = 0.001). The intercellular junctional complexes in the colonic epithelium were integral in FC patients. The distribution of mucosal occludin and ZO-1 was not altered in FC patients. No significant differences were found in occludin (control, 5.76E-2 ± 1.62E-2; FC, 5.17E-2 ± 1.80E-2; P = 0.240) and ZO-1 (control, 2.29E-2 ± 0.93E-2; FC, 2.68E-2 ± 1.60E-2; P = 0.333) protein expression between the two groups. The mRNA levels in occludin and ZO-1 were not modified in FC patients compared to healthy controls (P = 0.145, P = 0.451, respectively). No significant differences were observed in the number of CD3+ IELs per 100 epithelial cells (control, 5.62 ± 2.06; FC, 4.50 ± 2.16; P = 0.070) and CD3+ lamina propria lymphocytes (control, 19.69 ± 6.04/mm²; FC, 22.70 ± 11.38/mm²; P = 0.273). There were no significant differences in serum D-lactic acid [control, 5.21 (4.46, 5.49) mmol/L; FC, 4.63 (4.31, 5.42) mmol/L; P = 0.112] or zonulin [control, 1.36 (0.53, 2.15) ng/mL; FC, 0.94 (0.47, 1.56) ng/mL; P = 0.185] levels between FC patients and healthy controls.

CONCLUSION

The intestinal mucosal barrier in FC patients exhibits a compensatory increase in goblet cells and integral intercellular junctions without activation of mucosal immunity or increased gut permeability.

MTG16 (CBFA2T3) regulates colonic epithelial differentiation, colitis, and tumorigenesis by repressing E protein transcription factors

Aberrant epithelial differentiation and regeneration contribute to colon pathologies including inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). MTG16 (CBFA2T3) is a transcriptional corepressor expressed in the colonic epithelium. MTG16 deficiency in mice exacerbates colitis and increases tumor burden in CAC, though the underlying mechanisms remain unclear. Here, we identified MTG16 as a central mediator of epithelial differentiation, promoting goblet and restraining enteroendocrine cell development in homeostasis and enabling regeneration following dextran sulfate sodium (DSS)-induced colitis. Transcriptomic analyses implicated increased E box-binding transcription factor (E protein) activity in MTG16-deficient colon crypts. Using a novel mouse model with a point mutation that attenuates MTG16:E protein interactions (Mtg16P209T), we established that MTG16 exerts control over colonic epithelial differentiation and regeneration by repressing E protein-mediated transcription. Mimicking murine colitis, MTG16 expression was increased in biopsies from patients with active IBD compared to unaffected controls. Finally, uncoupling MTG16:E protein interactions partially phenocopied the enhanced tumorigenicity of Mtg16-/- colon in the azoxymethane(AOM)/DSS-induced model of CAC, indicating that MTG16 protects from tumorigenesis through additional mechanisms. Collectively, our results demonstrate that MTG16, via its repression of E protein targets, is a key regulator of cell fate decisions during colon homeostasis, colitis, and cancer.

An approach to p32/gC1qR/HABP1: a multifunctional protein with an essential role in cancer

P32/gC1qR/HABP1 is a doughnut-shaped acidic protein, highly conserved in eukaryote evolution and ubiquitous in the organism. Although its canonical subcellular localization is the mitochondria, p32 can also be found in the cytosol, nucleus, cytoplasmic membrane, and it can be secreted. Therefore, it is considered a multicompartmental protein. P32 can interact with many physiologically divergent ligands in each subcellular location and modulate their functions. The main ligands are C1q, hyaluronic acid, calreticulin, CD44, integrins, PKC, splicing factor ASF/SF2, and several microbial proteins. Among the functions in which p32 participates are mitochondrial metabolism and dynamics, apoptosis, splicing, immune response, inflammation, and modulates several cell signaling pathways. Notably, p32 is overexpressed in a significant number of epithelial tumors, where its expression level negatively correlates with patient survival. Several studies of gain and/or loss of function in cancer cells have demonstrated that p32 is a promoter of malignant hallmarks such as proliferation, cell survival, chemoresistance, angiogenesis, immunoregulation, migration, invasion, and metastasis. All of this strongly suggests that p32 is a potential diagnostic molecule and therapeutic target in cancer. Indeed, preclinical advances have been made in developing therapeutic strategies using p32 as a target. They include tumor homing peptides, monoclonal antibodies, an intracellular inhibitor, a p32 peptide vaccine, and p32 CAR T cells. These advances are promising and will allow soon to include p32 as part of targeted cancer therapies.

Gut-derived butyrate suppresses ocular surface inflammation

Dry eye is a common ocular inflammatory disorder characterized by tear film instability and reduced tear production. There is increasing evidence that homeostasis of the ocular surface is impacted by the intestinal microbiome. We are interested in investigating the potential role of microbially produced small molecules in mediating the interaction between the intestinal microbiota and the ocular surface. One such molecule is butyrate, a short-chain fatty acid (SCFA) produced by certain members of the gut microbiota through fermentation of dietary fiber. Here we show that SCFA transporter SLC5A8 is expressed in vivo in murine conjunctival and corneal epithelium. Pre-treatment of in vitro corneal epithelial cultures or bone marrow-derived dendritic cells (BMDCs) with phenylbutyrate (PBA) reduces lipopolysaccharide-induced pro-inflammatory Tnf expression. Corneal epithelial cultures and BMDCs isolated from Slc5a8 knockout mice are unable to respond to PBA pre-treatment, suggesting that SLC5A8 is required for the protective effect of PBA. The treatment of mice undergoing desiccating stress (DS) with oral tributyrin, a prodrug form of butyrate, reduces inflammation at the ocular surface in vivo, and this effect partially requires SLC5A8. Finally, expression analysis on conjunctival tissue isolated from mice subjected to DS with and without tributyrin treatment revealed that treatment downregulated genes involved in Type I interferon signaling. Together these data support our hypothesis that SCFAs produced in the gut participate in the maintenance of ocular surface homeostasis.

Mucosal Gene Transcript Signatures in Treatment Naïve Inflammatory Bowel Disease: A Comparative Analysis of Disease to Symptomatic and Healthy Controls in the European IBD-Character Cohort

Background

Studies of the mucosal transcriptomic landscape have given new insight into the pathogenesis of inflammatory bowel disease (IBD). Recently, the predictive biomarker potential of gene expression signatures has been explored. To further investigate the mucosal gene expression in IBD, we recruited a cohort of treatment naïve patients and compared them to both symptomatic and healthy controls.

Methods

Altogether, 323 subjects were included: Crohn’s disease (N = 75), ulcerative colitis (N = 87) and IBD unclassified (N = 3). Additionally, there were two control groups: symptomatic controls (N = 131) and healthy controls (N = 27). Mucosal biopsies were collected during ileocolonoscopy and gene expression in inflamed and non-inflamed mucosa was explored. Gene expression profiling was performed using Agilent G3 Human Gene Expression 860K v3 One-Color microarray. We recorded information about treatment escalation to anti-TNF agents or surgery, and anti-TNF response, to explore predictive opportunities of the mucosal transcriptome.

Results

Gene expression profiles in symptomatic controls in whom IBD had been excluded resembled that of IBD patients and diverged from that of healthy controls. In non-inflamed Crohn’s disease and ulcerative colitis, gene set enrichment analysis revealed dysregulation of pathways involved in basic cellular biological processes. Mitochondria-associated pathways were dysregulated both in non-inflamed and inflamed Crohn’s disease and ulcerative colitis (>2.6 normalized enrichment scores <−1.8). Gene expression signatures of Crohn’s disease and ulcerative colitis did not predict time for treatment escalation (p = 0.175). No significant association was found between gene expression signatures and anti-TNF response.

Conclusion

Non-inflamed samples are probably superior to inflamed samples when exploring gene expression signatures in IBD and might reveal underlying mechanisms central for disease initiation. The gene expression signatures of the control groups were related to if they were symptomatic or not, which may have important implications for future study designs.

Cellular metabolic basis of altered immunity in the lungs of patients with COVID-19

Metabolic pathways drive cellular behavior. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes lung tissue damage directly by targeting cells or indirectly by producing inflammatory cytokines. However, whether functional alterations are related to metabolic changes in lung cells after SARS-CoV-2 infection remains unknown. Here, we analyzed the lung single-nucleus RNA-sequencing (snRNA-seq) data of several deceased COVID-19 patients and focused on changes in transcripts associated with cellular metabolism. We observed upregulated glycolysis and oxidative phosphorylation in alveolar type 2 progenitor cells, which may block alveolar epithelial differentiation and surfactant secretion. Elevated inositol phosphate metabolism in airway progenitor cells may promote neutrophil infiltration and damage the lung barrier. Further, multiple metabolic alterations in the airway goblet cells are associated with impaired muco-ciliary clearance. Increased glycolysis, oxidative phosphorylation, and inositol phosphate metabolism not only enhance macrophage activation but also contribute to SARS-CoV-2 induced lung injury. The cytotoxicity of natural killer cells and CD8⁺ T cells may be enhanced by glycerolipid and inositol phosphate metabolism. Glycolytic activation in fibroblasts is related to myofibroblast differentiation and fibrogenesis. Glycolysis, oxidative phosphorylation, and glutathione metabolism may also boost the aging, apoptosis and proliferation of vascular smooth muscle cells, resulting in pulmonary arterial hypertension. In conclusion, this preliminary study revealed a possible cellular metabolic basis for the altered innate immunity, adaptive immunity, and niche cell function in the lung after SARS-CoV-2 infection. Therefore, patients with COVID-19 may benefit from therapeutic strategies targeting cellular metabolism in future.

Leveraging diet to engineer the gut microbiome

Autoimmune diseases, including inflammatory bowel disease, multiple sclerosis and rheumatoid arthritis, have distinct clinical presentations but share underlying patterns of gut microbiome perturbation and intestinal barrier dysfunction. Their potentially common microbial drivers advocate for treatment strategies aimed at restoring appropriate microbiome function, but individual variation in host factors makes a uniform approach unlikely. In this Perspective, we consolidate knowledge on diet-microbiome interactions in local inflammation, gut microbiota imbalance and host immune dysregulation. By understanding and incorporating the effects of individual dietary components on microbial metabolic output and host physiology, we examine the potential for diet-based therapies for autoimmune disease prevention and treatment. We also discuss tools targeting the gut microbiome, such as faecal microbiota transplantation, probiotics and orthogonal niche engineering, which could be optimized using custom dietary interventions. These approaches highlight paths towards leveraging diet for precise engineering of the gut microbiome at a time of increasing autoimmune disease.

SARS-CoV-2 Exacerbates COVID-19 Pathology Through Activation of the Complement and Kinin Systems

Infection with SARS-CoV-2 triggers the simultaneous activation of innate inflammatory pathways including the complement system and the kallikrein-kinin system (KKS) generating in the process potent vasoactive peptides that contribute to severe acute respiratory syndrome (SARS) and multi-organ failure. The genome of SARS-CoV-2 encodes four major structural proteins - the spike (S) protein, nucleocapsid (N) protein, membrane (M) protein, and the envelope (E) protein. However, the role of these proteins in either binding to or activation of the complement system and/or the KKS is still incompletely understood. In these studies, we used: solid phase ELISA, hemolytic assay and surface plasmon resonance (SPR) techniques to examine if recombinant proteins corresponding to S1, N, M and E: (a) bind to C1q, gC1qR, FXII and high molecular weight kininogen (HK), and (b) activate complement and/or the KKS. Our data show that the viral proteins: (a) bind C1q and activate the classical pathway of complement, (b) bind FXII and HK, and activate the KKS in normal human plasma to generate bradykinin and (c) bind to gC1qR, the receptor for the globular heads of C1q (gC1q) which in turn could serve as a platform for the activation of both the complement system and KKS. Collectively, our data indicate that the SARS-CoV-2 viral particle can independently activate major innate inflammatory pathways for maximal damage and efficiency. Therefore, if efficient therapeutic modalities for the treatment of COVID-19 are to be designed, a strategy that includes blockade of the four major structural proteins may provide the best option.

Colorectal Cancer Progression Is Potently Reduced by a Glucose-Free, High-Protein Diet: Comparison to Anti-EGFR Therapy

Simple Summary

To study the interplay between nutrition and intestinal metabolism in the context of colitis-driven colorectal carcinoma (CRC), we here investigated a nutritional therapy strategy in the presence or absence of EGFR-directed antibody therapy in mice to treat established colitis-driven CRCs in vivo. After CRC development, mice were fed a control diet or an isoenergetic glucose-free high-protein (GFHP) diet in the presence or absence of EGFR-directed antibody therapy. The GFHP diet was accompanied by a metabolic shift of the mice towards lower glycolysis activity. Both, GFHP diet or anti-EGFR antibody treatment, improved tumor differentiation and anti-tumor immune response, resulting in an efficient reduction of colonic tumor burden.

Abstract

To enable rapid proliferation, colorectal tumor cells up-regulate epidermal growth factor receptor (EGFR) signaling and aerobic glycolysis, resulting in substantial lactate release into the tumor microenvironment and impaired anti-tumor immune responses. We hypothesized that a nutritional intervention designed to reduce aerobic glycolysis may boost the EGFR-directed antibody (Ab)-based therapy of pre-existing colitis-driven colorectal carcinoma (CRC). CRC development was induced by azoxymethane (AOM) and dextran sodium sulfate (DSS) administration to C57BL/6 mice. AOM/DSS-treated mice were fed a glucose-free, high-protein diet (GFHPD) or an isoenergetic control diet (CD) in the presence or absence of an i.p. injection of an anti-EGFR mIgG2a or respective controls. AOM/DSS-treated mice on a GFHPD displayed a reduced systemic glucose metabolism associated with reduced oxidative phosphorylation (OXPHOS) complex IV expression and diminished tumor loads. Comparable but not additive to an anti-EGFR-Ab therapy, the GFHPD was accompanied by enhanced tumoral goblet cell differentiation and decreased colonic PD-L1 and splenic CD3ε, as well as PD-1 immune checkpoint expression. In vitro, glucose-free, high-amino acid culture conditions reduced proliferation but improved goblet cell differentiation of murine and human CRC cell lines MC-38 and HT29-MTX in combination with down-regulation of PD-L1 expression. We here found GFHPD to systemically dampen glycolysis activity, thereby reducing CRC progression with a similar efficacy to EGFR-directed antibody therapy.

Mitochondria and Inflammatory Bowel Diseases: Toward a Stratified Therapeutic Intervention

Mitochondria serve numerous critical cellular functions, rapidly responding to extracellular stimuli and cellular demands while dynamically communicating with other organelles. Mitochondrial function in the gastrointestinal epithelium plays a critical role in maintaining intestinal health. Emerging studies implicate the involvement of mitochondrial dysfunction in inflammatory bowel disease (IBD). This review presents mitochondrial metabolism, function, and quality control that converge in intestinal epithelial stemness, differentiation programs, barrier integrity, and innate immunity to influence intestinal inflammation. Intestinal and disease characteristics that set the stage for mitochondrial dysfunction being a key factor in IBD, and in turn, pathogenic mitochondrial mechanisms influencing and potentiating the development of IBD, are discussed. These findings establish the basis for potential mitochondrial-targeted interventions for IBD therapy. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Twenty-five years of biologicals in IBD: What´s all the hype about?

Twenty-five years ago the field was revolutionized by the introduction of infliximab as the first hybrid anti-TNF-antibody. Subsequently, other humanized anti-TNFs were developed and marketed, followed by antibodies to new targets including integrins (vedolizumab) and interleukin 12/23 (ustekinumab). All these so-called biologicals were shown in registrational trials to induce remission superior to placebo but consistently were effective in only a minority of patients. Even though in most trials only the responders were selected to continue on the respective medication for maintenance, many experienced a secondary loss of response and only a minority of usually <25% of the initial cohort achieved long-term (1 year) remission. In 'real life studies', the outcome was somewhat better, probably due to proper selection of patients and open, mostly retrospective study designs. A clear benefit of biologicals is apparent in otherwise treatment refractory patients, in extraintestinal manifestations and in Crohn´s disease (CD) with fistulizing complications. Biologicals achieve mucosal healing (MH) more often than corticosteroids or thiopurines, and MH is associated with improved prognosis. However, this does not justify escalating treatment until MH is reached since controlled trials proving this point of 'treat to target' are lacking both in ulcerative colitis and CD. Surgical rates have decreased with increasing use of biologicals, but disease progression has not been proven to improve. With the exception of opportunistic infections, serious adverse events are rare. In conclusion, biologicals have changed the scene considerably and expanded our armamentarium, but there is also a marketing hype fostering expectations without evidence.