Fecal lipocalin 2, a sensitive and broadly dynamic non-invasive biomarker for intestinal inflammation

Aryl hydrocarbon receptor signals in epithelial cells govern the recruitment and location of Helios+ Tregs in the gut

CD4⁺Foxp3⁺ regulatory T cells (Tregs) are essential for homeostasis in the colon, but the mechanism by which local environmental cues determine the localization of colonic Tregs is unclear. Here, we administer indigo naturalis (IN), a nontoxic phytochemical aryl hydrocarbon receptor (AhR) agonist used for treating patients with ulcerative colitis (UC) in Asia, and we show that IN increases Helios⁺ Tregs and MHC class II⁺ epithelial cells (ECs) in the colon. Interactions between Tregs and MHC class II⁺ ECs occur mainly near the crypt bottom in the steady state, whereas Tregs dramatically increase and shift toward the crypt top following IN treatment. Moreover, the number of CD25⁺ T cells is increased near the surface of ECs in IN-treated UC patients compared with that in patients treated with other therapies. We also highlight additional AhR-signaling mechanisms in intestinal ECs that determine the accumulation and localization of Helios⁺ Tregs in the colon.

Colitis-associated microbiota drives changes in behaviour in male mice in the absence of inflammation

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions of the gastrointestinal tract. IBD are associated with a high prevalence of cognitive, behavioural and emotional comorbidities, including anxiety and depression. The link between IBD and the development of behavioural comorbidities is poorly understood. As the intestinal microbiota profoundly influences host behaviour, we sought to determine whether the altered gut microbiota associated with intestinal inflammation contributes to the development of behavioural abnormalities. Using the dextran sulphate sodium (DSS) model of colitis, we characterized intestinal inflammation, behaviour (elevated plus maze and tail suspension test) and the composition of the microbiota in male mice. Cecal contents from colitic mice were transferred into germ-free (GF) or antibiotic (Abx)-treated mice, and behaviour was characterized in recipient mice. Gene expression was measured using qPCR. DSS colitis was characterized by a significant reduction in body weight and an increase in colonic inflammatory markers. These changes were accompanied by increased anxiety-like behaviour, an altered gut microbiota composition, and increased central Tnf expression. Transfer of the cecal matter from colitic mice induced similar behavioural changes in both GF and Abx-treated recipient mice, with no signs of colonic or neuroinflammation. Upon characterization of the microbiota in donor and recipient mice, specific taxa were found to be associated with behavioural changes, notably members of the Lachnospiraceae family. Behavioural abnormalities associated with intestinal inflammation are transmissible via transfer of cecal matter, suggesting that alterations in the composition of the gut microbiota play a key role in driving behavioural changes in colitis.

Lipocalin 2 potentially contributes to tumorigenesis from colitis via IL-6/STAT3/NF-kB signaling pathway

Lipocalin 2 (LCN2), a member of the lipocalin superfamily, plays an important role in oncogenesis and progression in various types of cancer. However, the role of LCN2 in inflammation-associated cancer remains unknown. Here, we explored the functional role and mechanisms of LCN2 in tumorigenesis using murine colitis-associated cancer (CAC) models and human colorectal cancer (CRC) cells. Using murine CAC models, we found that LCN2 was preferentially expressed in colonic tissues from CAC models compared to tissues from normal mice. In vitro results demonstrated that the levels of LCN2 mRNA and protein were markedly up-regulated by Interleukin-6 (IL-6) in human CRC cells. Interestingly, we found LCN2 up-regulation by IL-6 is diminished by NF-kB and STAT3 inhibition using specific inhibitors and siRNA. Reporter assay results determined that IL-6 induces LCN2 gene promoter activity under control of NF-kB/STAT3 activation. IL-6-induced LCN2 regulated cell survival and susceptibility of developmental factors to the NF-kB/STAT3 pathway. Taken together, our results highlight the unknown role of LCN2 in CAC progression and suggest that increased LCN2 may serve as an indicator of CRC development in the setting of chronic inflammation.

The expression of virulence genes increases membrane permeability and sensitivity to envelope stress in Salmonella Typhimurium

Virulence gene expression can represent a substantial fitness cost to pathogenic bacteria. In the model entero-pathogen Salmonella Typhimurium (S.Tm), such cost favors emergence of attenuated variants during infections that harbor mutations in transcriptional activators of virulence genes (e.g., hilD and hilC). Therefore, understanding the cost of virulence and how it relates to virulence regulation could allow the identification and modulation of ecological factors to drive the evolution of S.Tm toward attenuation. In this study, investigations of membrane status and stress resistance demonstrate that the wild-type (WT) expression level of virulence factors embedded in the envelope increases membrane permeability and sensitizes S.Tm to membrane stress. This is independent from a previously described growth defect associated with virulence gene expression in S.Tm. Pretreating the bacteria with sublethal stress inhibited virulence expression and increased stress resistance. This trade-off between virulence and stress resistance could explain the repression of virulence expression in response to harsh environments in S.Tm. Moreover, we show that virulence-associated stress sensitivity is a burden during infection in mice, contributing to the inherent instability of S.Tm virulence. As most bacterial pathogens critically rely on deploying virulence factors in their membrane, our findings could have a broad impact toward the development of antivirulence strategies.

Large-scale serum analysis identifies unique systemic biomarkers in psoriasis and hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is now recognized as a systemic inflammatory disease, sharing molecular similarities with psoriasis. Direct comparison of the systemic inflammation in HS with psoriasis is lacking.

OBJECTIVES

To evaluate the serum proteome of HS and psoriasis, and to identify biomarkers associated with disease severity.

METHODS

In this cross-sectional study, 1536 serum proteins were assessed using the Olink Explore (Proximity Extension Assay) high-throughput panel in patients with moderate-to-severe HS (n = 11), patients with psoriasis (n = 10) and age- and body mass index-matched healthy controls (n = 10).

RESULTS

HS displayed an overall greater dysregulation of circulating proteins, with 434 differentially expressed proteins (absolute fold change ≥ 1·2; P ≤ 0·05) in patients with HS vs. controls, 138 in patients with psoriasis vs. controls and 503 between patients with HS and patients with psoriasis. Interleukin (IL)-17A levels and T helper (Th)1/Th17 pathway enrichment were comparable between diseases, while HS presented greater tumour necrosis factor- and IL-1β-related signalling. The Th17-associated markers peptidase inhibitor 3 (PI3) and lipocalin 2 (LCN2) were able to differentiate psoriasis from HS accurately. Both diseases presented increases of atherosclerosis-related proteins. Robust correlations between clinical severity scores and immune and atherosclerosis-related proteins were observed across both diseases.

CONCLUSIONS

HS and psoriasis share significant Th1/Th17 enrichment and upregulation of atherosclerosis-related proteins. Despite the greater body surface area involved in psoriasis, HS presents a greater serum inflammatory burden.

Effects of different amino acid levels and a carvacrol-thymol blend on growth performance and intestinal health of weaned pigs

Background

Over the past years, antibiotic growth promoter had been restricted in animal husbandry production in many countries because of antimicrobial resistance and foodborne antibiotic residues. However, the problems of poor intestinal health and low growth efficiency of piglets have not been solved completely in an antibiotic-free diet, and it is urgent to explore alternatives to antimicrobial growth promoters.

Methods

Here, a total of 532 weaned pigs were assigned to one of 4 treatments, the low amino acid (AA) level diet (d 1 to d 14 is 1.35%, d 15 to d 42 is 1.25%) (Low AA), the low AA level diet supplementation with a carvacrol–thymol blend (50 mg carvacrol and 50 mg thymol/kg of diet) (CB) (Low AA+CB), the high AA level diet (d 1 to d 14 is 1.50%, d 15 to d 42 is 1.40%) (High AA), and the high AA level diet supplementation with a CB (High AA+CB), respectively. Then we measured growth performance and intestinal health indicators of weaned pigs.

Results

Results showed that high AA level significantly reduced plasma urea nitrogen, plasma Interleukin-6 (IL-6) and fecal lipocalin-2 contents (P <  0.05), significantly increased the relative abundance of fecal Lactobacillus and Enterococcus, and had a trend to increase the fecal secretory immunoglobulin A (sIgA) and mucin 2 (MUC 2) contents (P <  0.05) in piglets, thereby alleviating the diarrhea of piglets and reducing the feed conversion ratio (FCR) of piglets during d 1~14 after weaning. Dietary supplementation with CB significantly increased the activity of plasma antioxidant enzymes T-SOD and GSH-px (P <  0.05), while significantly reduced plasma malondialdehyde (MDA), plasma interleukin-1β (IL-1β), plasma endotoxin and D-lactic acid contents (P <  0.05). Meanwhile, CB significantly decreased fecal lipocalin-2 contents and the abundance of fecal Escherichia coli (P < 0.05). Thus, we hypothesis that dietary supplementation with CB significantly increased the average daily gain (ADG) of piglets (P < 0.05) during d 1~14 after weaning through promoting intestinal health.

Conclusion

These results suggest that high AA level and dietary supplementation with CB improved the growth performance of weaned pigs in an antibiotic-free diet by improving AA metabolism and intestinal antioxidant capacity.

Social overcrowding impacts gut microbiota, promoting stress, inflammation, and dysglycemia

An array of chronic inflammatory diseases, including metabolic diseases such as obesity and diabetes, are thought to be promoted by disturbance of the intestinal microbiota. Such diseases disproportionately impact low-income communities, which are frequently afflicted by chronic stress and increased density housing. Hence, we hypothesized that overcrowded housing might promote stress, microbiota dysbiosis, inflammation, and, consequently, metabolic diseases. We tested this hypothesis in a tractable murine model of social overcrowding (SOC), in which mice were housed at twice normal density. SOC moderately impacted behavior in some widely used assays (Open Field, Elevated Plus Maze and Light/Dark tests) and resulted in a stark increase in corticosterone levels. Such indices of stress were associated with mild chronic gut inflammation, hyperglycemia, elevations in colonic cytokines, and alterations in gut microbiota composition. All of these consequences of SOC were eliminated by broad spectrum antibiotics, while some (inflammation and hyperglycemia) were transmitted by microbiota transplantation from SOC mice to germfree mice housed at normal density. Altogether, these results suggest a central role for intestinal microbiota in driving stress, inflammation, and chronic diseases that are promoted by overcrowded housing.

Randomized Controlled-Feeding Study of Dietary Emulsifier Carboxymethylcellulose Reveals Detrimental Impacts on the Gut Microbiota and Metabolome

BACKGROUND & AIMS

Epidemiologic and murine studies suggest that dietary emulsifiers promote development of diseases associated with microbiota dysbiosis. Although the detrimental impact of these compounds on the intestinal microbiota and intestinal health have been demonstrated in animal and in vitro models, impact of these food additives in healthy humans remains poorly characterized.

METHODS

To examine this notion in humans, we performed a double-blind controlled-feeding study of the ubiquitous synthetic emulsifier carboxymethylcellulose (CMC) in which healthy adults consumed only emulsifier-free diets (n = 9) or an identical diet enriched with 15 g per day of CMC (n = 7) for 11 days.

RESULTS

Relative to control subjects, CMC consumption modestly increased postprandial abdominal discomfort and perturbed gut microbiota composition in a way that reduced its diversity. Moreover, CMC-fed subjects exhibited changes in the fecal metabolome, particularly reductions in short-chain fatty acids and free amino acids. Furthermore, we identified 2 subjects consuming CMC who exhibited increased microbiota encroachment into the normally sterile inner mucus layer, a central feature of gut inflammation, as well as stark alterations in microbiota composition.

CONCLUSIONS

These results support the notion that the broad use of CMC in processed foods may be contributing to increased prevalence of an array of chronic inflammatory diseases by altering the gut microbiome and metabolome (ClinicalTrials.gov, number NCT03440229).

Pomegranate Extract Improves Colitis in IL-10 Knockout Mice Fed a High Fat High Sucrose Diet

SCOPE

The study tests the hypothesis that dietary pomegranate extract (PomX) supplementation attenuates colitis in a Western diet feed IL-10 deficient (IL-10-/-) murine model.

METHODS AND RESULTS

Four-week-old male IL-10-/- mice are randomly assigned to a high fat high sucrose (HFHS) diet or a HFHS diet supplement with 0.25% PomX for 8 weeks. PomX supplementation lead to significantly lower histological score for colitis (2.6 ± 0.5 vs 3.9 ± 1.0), lower spleen weight (0.11 ± 0.01 vs 0.15 ± 0.02), and lower circulating Interleukin 6(IL-6) levels (15.8±2.2 vs 29.5±5.5) compared with HFHS fed controls. RNAseq analysis of colonic tissues showed 483 downregulated and 263 upregulated genes with PomX supplementation, which are mainly associated with inflammatory responses, defenses, and neutrophil degranulation. In addition, PomX treatment affects the cecal microbiome with increased alpha diversity, altered microbial composition, and increased levels of the tryptophan-related microbial metabolite indole propionate.

CONCLUSION

The data demonstrate that dietary PomX supplementation ameliorated colitis and lowered inflammatory markers in HFHS fed IL-10-/- mice. These data support the anti-inflammatory effects of dietary PomX supplementation for IBD and a potential mediating role of gut microbiome, suggesting the need for future clinical studies to explore the use of PomX dietary supplementation in IBD patients.

Compensatory intestinal antibody response against pro-inflammatory microbiota after bariatric surgery

Obesity and type 2 diabetes (T2D) are growing burdens for individuals and the health-care system. Bariatric surgery is an efficient, but drastic treatment to reduce body weight, normalize glucose values, and reduce low-grade inflammation. The gut microbiome, which is in part controlled by intestinal antibodies, such as IgA, is involved in the development of both conditions. Knowledge of the effect of bariatric surgery on systemic and intestinal antibody response is limited. Here, we determined the fecal antibody and gut microbiome response in 40 T2D and non-diabetic (ND) obese individuals that underwent bariatric surgery (N = 40). Body weight, fasting glucose concentrations and inflammatory parameters decreased after bariatric surgery, whereas pro-inflammatory bacterial species such as lipopolysaccharide (LPS), and flagellin increased in the feces. Simultaneously, concentrations of LPS- and flagellin-specific intestinal IgA levels increased with the majority of pro-inflammatory bacteria coated with IgA after surgery. Finally, serum antibodies decreased in both groups, along with a lower inflammatory tone. We conclude that intestinal rearrangement by bariatric surgery leads to expansion of typical pro-inflammatory bacteria, which may be compensated by an improved antibody response. Although further evidence and mechanistic insights are needed, we postulate that this apparent compensatory antibody response might help to reduce systemic inflammation by neutralizing intestinal immunogenic components and thereby enhance intestinal barrier function after bariatric surgery.

Executioner caspases 3 and 7 are dispensable for intestinal epithelium turnover and homeostasis at steady state

Historically, programmed cell death by apoptosis is considered crucial for proper intestinal organogenesis and gut homeostasis. To challenge this concept, we generated caspase-3 and -7 double knockout mice specifically in intestinal epithelial cells (IECs). However, absence of apoptosis in IECs elicits neither morphological and inflammatory changes nor intestinal dysbiosis during gut homeostasis at steady state. This demonstrates the robustness of intestinal homeostasis at steady state for the absence of caspase-3/7 and shows that in contrast to caspase-8, which keeps necroptosis and associated inflammation in check, caspase-3/7–dependent apoptosis of IECs in homeostatic conditions is dispensable for normal intestinal development, immune cell composition, and microbiome control.

Apoptosis is widely believed to be crucial for epithelial cell death and shedding in the intestine, thereby shaping the overall architecture of the gastrointestinal tract, but also regulating tolerance induction, pinpointing a role of apoptosis intestinal epithelial cell (IEC) turnover and maintenance of barrier function, and in maintaining immune homeostasis. To experimentally address this concept, we generated IEC-specific knockout mice that lack both executioner caspase-3 and caspase-7 (Casp3/7^ΔIEC), which are the converging point of the extrinsic and intrinsic apoptotic pathway. Surprisingly, the overall architecture, cellular landscape, and proliferation rate remained unchanged in these mice. However, nonapoptotic cell extrusion was increased in Casp3/7^ΔIEC mice, compensating apoptosis deficiency, maintaining the same physiological level of IEC shedding. Microbiome richness and composition stayed unaffected, bearing no sign of dysbiosis. Transcriptome and single-cell RNA sequencing analyses of IECs and immune cells revealed no differences in signaling pathways of differentiation and inflammation. These findings demonstrate that during homeostasis, apoptosis per se is dispensable for IEC turnover at the top of intestinal villi intestinal tissue dynamics, microbiome, and immune cell composition.

A Potential Role of Ethosuximide and Pentoxifylline in Relieving Abdominal Pain in Irritable Bowel Syndrome Patients Treated with Mebeverine: A Randomized, Double-Blind, Placebo-Controlled Trial

Background and Purpose

Irritable bowel syndrome (IBS) is defined as an association of chronic abdominal pain with bowel habit abnormalities, without clear organic dysfunction. T-type calcium channels and low-grade mucosal inflammation are linked to abdominal pain; however, medical treatments for IBS abdominal pain are largely ineffective. In this study, we investigated if pentoxifylline (PTX) and ethosuximide could potentially alleviate abdominal pain in patients with IBS treated with mebeverine.

Methods

We recruited 150 patients from Tanta University Hospital to this randomized, prospective, and double blinded study. Patients were randomly allocated to three groups (n = 50). Group 1 (mebeverine) received 135 mg mebeverine three times/day (t.i.d). Group 2 (ethosuximide group) received 135 mg mebeverine t.i.d plus 250 mg ethosuximide twice daily (b.i.d) and group 3 (PTX group) received 135 mg mebeverine t.i.d plus 400 mg PTX b.i.d. Patients were assessed by a gastroenterologist at baseline and 6 months after therapy. Serum interleukin-8 (IL-8), IL-6, tumor necrosis-α (TNF-α), fecal myeloperoxidase, and fecal neutrophil gelatinase associated lipocalin (NGAL) levels were measured before and after therapy. The numeric pain rating scale (NRS) was also assessed before and after therapy.

Primary Outcomes

Reduced NRS scores and abdominal pain relief.

Secondary Outcomes

Decreased inflammatory biomarkers.

Results

After 6 months, groups 2 and 3 showed a significantly greater reduction in serum IL-8, IL-6, TNF-α, fecal myeloperoxidase, and fecal NGAL levels when compared to group 1 after therapy. Both groups 2 and 3 showed significant reductions in NRS scores when compared to the group 1.

Conclusion

Ethosuximide and PTX may be promising, novel adjunct drugs to antispasmodics for relieving abdominal pain in patients with IBS.

Trial Registration

Identifier: NCT04217733.

Multi-omics analyses of the ulcerative colitis gut microbiome link Bacteroides vulgatus proteases with disease severity

Ulcerative colitis (UC) is driven by disruptions in host-microbiota homoeostasis, but current treatments exclusively target host inflammatory pathways. To understand how host-microbiota interactions become disrupted in UC, we collected and analysed six faecal- or serum-based omic datasets (metaproteomic, metabolomic, metagenomic, metapeptidomic and amplicon sequencing profiles of faecal samples and proteomic profiles of serum samples) from 40 UC patients at a single inflammatory bowel disease centre, as well as various clinical, endoscopic and histologic measures of disease activity. A validation cohort of 210 samples (73 UC, 117 Crohn's disease, 20 healthy controls) was collected and analysed separately and independently. Data integration across both cohorts showed that a subset of the clinically active UC patients had an overabundance of proteases that originated from the bacterium Bacteroides vulgatus. To test whether B. vulgatus proteases contribute to UC disease activity, we first profiled B. vulgatus proteases found in patients and bacterial cultures. Use of a broad-spectrum protease inhibitor improved B. vulgatus-induced barrier dysfunction in vitro, and prevented colitis in B. vulgatus monocolonized, IL10-deficient mice. Furthermore, transplantation of faeces from UC patients with a high abundance of B. vulgatus proteases into germfree mice induced colitis dependent on protease activity. These results, stemming from a multi-omics approach, improve understanding of functional microbiota alterations that drive UC and provide a resource for identifying other pathways that could be inhibited as a strategy to treat this disease.

Helicobacter hepaticus is required for immune targeting of bacterial heat shock protein 60 and fatal colitis in mice

Gut microbiota and the immune system are in constant exchange shaping both host immunity and microbial communities. Here, improper immune regulation can cause inflammatory bowel disease (IBD) and colitis. Antibody therapies blocking signaling through the CD40-CD40L axis showed promising results as these molecules are deregulated in certain IBD patients. To better understand the mechanism, we used transgenic DC-LMP1/CD40 animals with a constitutive CD40-signal in CD11c⁺ cells, causing a lack of intestinal CD103⁺ dendritic cells (DCs) and failure to induce regulatory T (iTreg) cells. These mice rapidly develop spontaneous fatal colitis, accompanied by dysbiosis and increased inflammatory IL-17⁺IFN-γ⁺ Th17/Th1 and IFN-γ ⁺ Th1 cells. In the present study, we analyzed the impact of the microbiota on disease development and detected elevated IgA- and IgG-levels in sera from DC-LMP1/CD40 animals. Their serum antibodies specifically bound intestinal bacteria, and by proteome analysis, we identified a 60 kDa chaperonin GroEL (Hsp60) from Helicobacter hepaticus (Hh) as the main specific antigen targeted in the absence of iTregs. When re-derived to a different Hh-free specific-pathogen-free (SPF) microbiota, mice showed few signs of disease, normal microbiota, and no fatality. Upon recolonization of mice with Hh, the disease developed rapidly. Thus, the present work identifies GroEL/Hsp60 as a major Hh-antigen and its role in disease onset, progression, and outcome in this colitis model. Our results highlight the importance of CD103⁺ DC- and iTreg-mediated immune tolerance to specific pathobionts to maintain healthy intestinal balance.

Lactate-utilizing bacteria ameliorates DSS-induced colitis in mice

Inflammatory bowel diseases (IBD) stem from alterations in the intestinal immune system and microbial dysbiosis, but the precise interactions between bacteria and IBD remain obscure. The commensal microbiota have a profound impact on human health and diseases. Here, we developed a selective culture medium for lactate-utilizing bacteria (LUB) that function as candidate probiotics to ameliorate IBD using a mouse model. Firstly, LUB, including Megasphaera, were enriched from human faeces using a selective medium with lactate. LUB efficiently attenuated the pathology of colitis induced by dextran sulphate sodium (DSS). Next, LUB administration counteracted the dysbiosis associated with the intestinal inflammatory process, and elevated the proportion of Escherichia-Shigella in intestines. Moreover, E. coli isolated from healthy faeces downstream recapitulated lactate-utilizing bacterial community to ameliorate the severity of DSS-induced acute colitis. In conclusion, our finding revealed that LUB were sufficient to exert inflammatory protection against colitis in mice, highlighting a novel therapeutic strategy to use LUB as potentially curable probiotics for therapeutic manipulation for IBD.

AhR/IL-22 pathway as new target for the treatment of post-infectious irritable bowel syndrome symptoms

Alterations in brain/gut/microbiota axis are linked to Irritable Bowel Syndrome (IBS) physiopathology. Upon gastrointestinal infection, chronic abdominal pain and anxio-depressive comorbidities may persist despite pathogen clearance leading to Post-Infectious IBS (PI-IBS). This study assesses the influence of tryptophan metabolism, and particularly the microbiota-induced AhR expression, on intestinal homeostasis disturbance following gastroenteritis resolution, and evaluates the efficacy of IL-22 cytokine vectorization on PI-IBS symptoms. The Citrobacter rodentium infection model in C57BL6/J mice was used to mimic Enterobacteria gastroenteritis. Intestinal homeostasis was evaluated as low-grade inflammation, permeability, mucosa-associated microbiota composition, and colonic sensitivity. Cognitive performances and emotional state of animals were assessed using several tests. Tryptophan metabolism was analyzed by targeted metabolomics. AhR activity was evaluated using a luciferase reporter assay method. One Lactococcus lactis strain carrying an eukaryotic expression plasmid for murine IL-22 (L. lactisIL-22) was used to induce IL-22 production in mouse colonic mucosa. C. rodentium-infected mice exhibited persistent colonic hypersensitivity and cognitive impairments and anxiety-like behaviors after pathogen clearance. These post-infectious disorders were associated with low-grade inflammation, increased intestinal permeability, decrease of Lactobacillaceae abundance associated with the colonic layer, and increase of short-chain fatty acids (SCFAs). During post-infection period, the indole pathway and AhR activity were decreased due to a reduction of tryptophol production. Treatment with L. lactisIL-22 restored gut permeability and normalized colonic sensitivity, restored cognitive performances and decreased anxiety-like behaviors. Data from the video-tracking system suggested an upgrade of welfare for mice receiving the L.lactisIL-22 strain. Our findings revealed that AhR/IL-22 signaling pathway is altered in a preclinical PI-IBS model. IL-22 delivering alleviate PI-IBS symptoms as colonic hypersensitivity, cognitive impairments, and anxiety-like behaviors by acting on intestinal mucosa integrity. Thus, therapeutic strategies targeting this pathway could be developed to treat IBS patients suffering from chronic abdominal pain and associated well-being disorders.

High inflammation in hidradenitis suppurativa extends to perilesional skin and can be subdivided by lipocalin-2 expression

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease presenting with diverse manifestations ranging from nodules and abscesses to draining tunnels. Whether the underlying inflammation from lesions extends to relatively healthy-appearing adjacent perilesional and distant nonlesional skin has not been systematically evaluated.

OBJECTIVE

We sought to characterize lesional, perilesional, and nonlesional skin in patients with HS.

METHODS

Skin biopsy samples were collected under ultrasound guidance from patients with active, untreated moderate-to-severe HS. Site-matched control biopsy samples from healthy volunteers were used for comparison.

RESULTS

RNA sequencing demonstrated that HS skin clustered separately from healthy control skin, with perilesional and lesion skin clustering together and away from nonlesional skin. Immunohistochemistry analysis identified psoriasiform hyperplasia with keratin 16 positivity in both perilesional and lesional skin, with comparable levels of CD3+, CD11c+, and neutrophil elastase-positive cellular infiltration. There was a marked upregulation of IL-17 signaling in perilesional and lesional skin. HS samples clustered on the basis of expression of lipocalin-2 (LCN2), with samples characterized by high LCN2 expression in the skin exhibiting a differing transcriptomic profile with significantly higher overall inflammation than that of skin characterized by low LCN2 levels.

CONCLUSIONS

Perilesional HS skin has a transcriptomic and molecular profile comparable to that of lesional skin. HS can be grouped into 2 distinct subtypes based on molecular levels of LCN2 in the skin, with the LCN2-high subtype exhibiting an overall higher inflammatory burden and an upregulation of targetable cytokines. To our knowledge, this is the first study to characterize a unique HS subtype (and a potential endotype) that may guide future therapeutic targets.

Diet standardization reduces intra-individual microbiome variation

The human gut microbiota is highly heterogenous between individuals and also exhibits considerable day-to-day variation within individuals. We hypothesized that diet contributed to such inter- and/or intra-individual variance. Hence, we investigated the extent to which diet normalization impacted microbiota heterogeneity. We leveraged the control arm of our recently reported controlled-feeding study in which nine healthy individuals consumed a standardized additive-free diet for 10 days. Diet normalization did not impact inter-individual differences but reduced the extent of intra-individual day-to-day variation in fecal microbiota composition. Such decreased heterogeneity reflected individual-specific enrichment and depletion of an array of taxa microbiota members and was paralleled by a trend toward reduced intra-individual variance in fecal LPS and flagellin, which, collectively, reflect microbiota's pro-inflammatory potential. Yet, the microbiota of some subjects did not change significantly over the course of the study, suggesting heterogeneity in microbiota resilience to dietary stress or that baseline diets of some subjects were perhaps similar to our study's standardized diet. Collectively, our results indicate that short-term diet heterogeneity contributes to day-to-day intra-individual microbiota composition variance.

Lipocalin-2 and calprotectin as stool biomarkers for predicting necrotizing enterocolitis in premature neonates

BACKGROUND

Necrotizing enterocolitis (NEC) is a major challenge for premature infants in neonatal intensive care units and efforts toward the search for indicators that could be used to predict the development of the disease have given limited results until now.

METHODS

In this study, stools from 132 very low birth weight infants were collected daily in the context of a multi-center prospective study aimed at investigating the potential of fecal biomarkers for NEC prediction. Eight infants (~6%) received a stage 3 NEC diagnosis. Their stools collected up to 10 days before diagnosis were included and matched with 14 non-NEC controls and tested by ELISA for the quantitation of eight biomarkers.

RESULTS

Biomarkers were evaluated in all available stool samples leading to the identification of lipocalin-2 and calprotectin as the two most reliable predicting markers over the 10-day period prior to NEC development. Pooling the data for each infant confirmed the significance of lipocalin-2 and calprotectin, individually and in combination 1 week in advance of the NEC clinical diagnosis.

CONCLUSIONS

The lipocalin-2 and calprotectin tandem represents a significant biomarker signature for predicting NEC development. Although not yet fulfilling the "perfect biomarker" criteria, it represents a first step toward it.

IMPACT

Stool biomarkers can be used to predict NEC development in very low birth weight infants more than a week before the diagnosis. LCN2 was identified as a new robust biomarker for predicting NEC development, which used in conjunction with CALPRO, allows the identification of more than half of the cases that will develop NEC in very low birth weight infants. Combining more stool markers with the LCN2/CALPRO tandem such as PGE2 can further improve the algorithm for the prediction of NEC development.

Changes in Gut Bacterial Translation Occur before Symptom Onset and Dysbiosis in Dextran Sodium Sulfate-Induced Murine Colitis

Longitudinal studies on the gut microbiome that follow the effect of a perturbation are critical in understanding the microbiome's response and succession to disease. Here, we use a dextran sodium sulfate (DSS) mouse model of colitis as a tractable perturbation to study how gut bacteria change their physiology over the course of a perturbation. Using single-cell methods such as flow cytometry, bioorthogonal noncanonical amino acid tagging (BONCAT), and population-based cell sorting combined with 16S rRNA sequencing, we determine the diversity of physiologically distinct fractions of the gut microbiota and how they respond to a controlled perturbation. The physiological markers of bacterial activity studied here include relative nucleic acid content, membrane damage, and protein production. There is a distinct and reproducible succession in bacterial physiology, with an increase in bacteria with membrane damage and diversity changes in the translationally active fraction, both, critically, occurring before symptom onset. Large increases in the relative abundance of Akkermansia were seen in all physiological fractions, most notably in the translationally active bacteria. Performing these analyses within a detailed, longitudinal framework determines which bacteria change their physiology early on, focusing therapeutic efforts in the future to predict or even mitigate relapse in diseases like inflammatory bowel diseases. IMPORTANCE Most studies on the gut microbiome focus on the composition of this community and how it changes in disease. However, how the community transitions from a healthy state to one associated with disease is currently unknown. Additionally, common diversity metrics do not provide functional information on bacterial activity. We begin to address these two unknowns by following bacterial activity over the course of disease progression, using a tractable mouse model of colitis. We find reproducible changes in gut bacterial physiology that occur before symptom onset, with increases in the proportion of bacteria with membrane damage, and changes in community composition of the translationally active bacteria. Our data provide a framework to identify possible windows of intervention and which bacteria to target in microbiome-based therapeutics.

Anti-inflammatory and gut microbiota modulatory effects of polysaccharides from Fuzhuan brick tea on colitis in mice induced by dextran sulfate sodium

In this study, the effects of crude Fuzhuan brick tea polysaccharides (CFBTPS) and their purified fraction (FBTPS-3) on colitis induced by dextran sulfate sodium (DSS) in mice were investigated. Both CFBTPS and FBTPS-3 exhibited intestinal anti-inflammatory activities, including restoring body weight, colon length and solid fecal weight, and decreasing the disease activity index score in mice. Moreover, the expression of lipocalin-2 in colitis could be significantly reduced. The inflammatory cytokines (IL-6, IL-1β, IFN-γ and TNF-α) and lipopolysaccharides in the serum and the expression of inflammation-related mRNA in the colon tissue were decreased. Both CFBTPS and FBTPS-3 could increase tight junction proteins (Occludin, Claudin-1 and ZO-1), promoting the intestinal barrier function. For gut microbiota, DSS treatment resulted in abnormal proliferation of Bifidobacteria, while FBTPS-3 could restore this disorder to a certain extent. In addition, FBPTS-3 promoted the growth of probiotics such as Bacteroides, Parasutterella and Collinsella. Both CFBTPS and FBTPS-3 could attenuate colitis; what's more, FBTPS-3 exhibited a better anti-inflammatory effect than CFBTPS.

The immunotoxicity, but not anti-tumor efficacy, of anti-CD40 and anti-CD137 immunotherapies is dependent on the gut microbiota

Immune agonist antibodies (IAAs) are promising immunotherapies that target co-stimulatory receptors to induce potent anti-tumor immune responses, particularly when combined with checkpoint inhibitors. Unfortunately, their clinical translation is hampered by serious dose-limiting, immune-mediated toxicities, including high-grade and sometimes fatal liver damage, cytokine release syndrome (CRS), and colitis. We show that the immunotoxicity, induced by the IAAs anti-CD40 and anti-CD137, is dependent on the gut microbiota. Germ-free or antibiotic-treated mice have significantly reduced colitis, CRS, and liver damage following IAA treatment compared with conventional mice or germ-free mice recolonized via fecal microbiota transplant. MyD88 signaling is required for IAA-induced CRS and for anti-CD137-induced, but not anti-CD40-induced, liver damage. Importantly, antibiotic treatment does not impair IAA anti-tumor efficacy, alone or in combination with anti-PD1. Our results suggest that microbiota-targeted therapies could overcome the toxicity induced by IAAs without impairing their anti-tumor activity.

A High-Fat Western Diet Attenuates Intestinal Changes in Mice with DSS-Induced Low-Grade Inflammation

BACKGROUND

A Western diet (WD) is associated with increased inflammation in the large intestine, which is often ascribed to the high dietary fat content. Intestinal inflammation in rodents can be induced by oral administration of dextran sodium sulfate (DSS). However, most studies investigating effects of WD and DSS have not used appropriate low-fat diets (LFDs) as control.

OBJECTIVES

To compare the effects of a WD with those of an LFD on colon health in a DSS-induced low-grade colonic inflammation mouse model.

METHODS

Six-week-old male C57BL/6JRj mice were fed an LFD (fat = 10.3% energy, n = 24) or a WD (fat = 41.2% energy, n = 24) for 15 wk [Experiment 1 (Exp.1)]. Half the mice on each diet (n = 12) then received 1% DSS in water for 6 d with the remainder (n = 12 in each diet) administered water. Disease activity, proinflammatory genes, inflammatory biomarkers, and fecal microbiota (16S rRNA) were assessed (Exp.1). Follow-up experiments (Exp.2 and Exp.3) were performed to investigate whether fat source (milk or lard; Exp.2) affected outcomes and whether a shift from LFD to WD 1 d prior to 1% DSS exposure caused an immediate effect on DSS-induced inflammation (Exp.3).

RESULTS

In Exp.1, 1% DSS treatment significantly increased disease score in the LFD group compared with the WD group (2.7 compared with 0.8; P < 0.001). Higher concentrations of fecal lipocalin (11-fold; P < 0.001), proinflammatory gene expression (≤82-fold), and Proteobacteria were observed in LFD-fed mice compared with the WD group. The 2 fat sources in WDs (Exp.2) revealed the same low inflammation in WD+DSS mice compared with LFD+DSS mice. Finally, the switch from LFD to WD just before DSS exposure resulted in reduced colonic inflammation (Exp.3).

CONCLUSIONS

Herein, WDs (with milk or lard) protected mice against DSS-induced colonic inflammation compared with LFD-fed mice. Whether fat intake induces protective mechanisms against DSS-mediated inflammation or inhibits establishment of the DSS-induced colitis model is unclear.

STW 5 Herbal Preparation Modulates Wnt3a and Claudin 1 Gene Expression in Zebrafish IBS-like Model

Aim: Irritable bowel syndrome (IBS) is a functional bowel disorder characterized by chronic abdominal pain and stool irregularities. STW 5 has proven clinical efficacy in functional gastrointestinal disorders, including IBS, targeting pathways that suppress inflammation and protect the mucosa. Wnt signaling is known to modulate NF-kβ-dependent inflammatory cytokine production. This sparked the idea of evaluating the impact of STW 5 on the expression of inflammatory-response and Wnt/β catenin-target genes in an IBS-like model. Main methods: We used zebrafish and dextran sodium sulfate (DSS) treatment to model IBS-like conditions in vivo and in vitro and examined the effects of subsequent STW 5 treatment on the intestines of DSS-treated fish and primary cultured intestinal and neuronal cells. Gross gut anatomy, histology, and the expression of Wnt-signaling and cytokine genes were analyzed in treated animals and/or cells, and in controls. Key findings: DSS treatment up-regulated the expression of interleukin-8, tumor necrosis factor-α, wnt3a, and claudin-1 in explanted zebrafish gut. Subsequent STW 5 treatment abolished both the macroscopic signs of gut inflammation, DSS-induced mucosecretory phenotype, and normalized the DSS-induced upregulated expression of il10 and Wnt signaling genes, such as wnt3a and cldn1 in explanted zebrafish gut. Under inflammatory conditions, STW 5 downregulated the expression of the pro-inflammatory cytokine genes il1β, il6, il8, and tnfα while it upregulated the expression of the anti-inflammatory genes il10 and wnt3a in enteric neuronal cells in vitro. Significance: Wnt signaling could be a novel target for the anti-inflammatory and intestinal permeability-restoring effects of STW 5, possibly explaining its clinical efficacy in IBS.

Psychological stress impairs IL22-driven protective gut mucosal immunity against colonising pathobionts

Crohn's disease is an inflammatory disease of the gastrointestinal tract characterized by an aberrant response to microbial and environmental triggers. This includes an altered microbiome dominated by Enterobacteriaceae and in particular adherent-invasive E. coli (AIEC). Clinical evidence implicates periods of psychological stress in Crohn's disease exacerbation, and disturbances in the gut microbiome might contribute to the pathogenic mechanism. Here we show that stress-exposed mice develop ileal dysbiosis, dominated by the expansion of Enterobacteriaceae. In an AIEC colonisation model, stress-induced glucocorticoids promote apoptosis of CD45+CD90+ cells that normally produce IL-22, a cytokine that is essential for the maintenance of ileal mucosal barrier integrity. Blockade of glucocorticoid signaling or administration of recombinant IL-22 restores mucosal immunity, prevents ileal dysbiosis, and blocks AIEC expansion. We conclude that psychological stress impairs IL-22-driven protective immunity in the gut, which creates a favorable niche for the expansion of pathobionts that have been implicated in Crohn's disease. Importantly, this work also shows that immunomodulation can counteract the negative effects of psychological stress on gut immunity and hence disease-associated dysbiosis.

Pentoxifylline, a nonselective phosphodiesterase inhibitor, in adjunctive therapy in patients with irritable bowel syndrome treated with mebeverine

BACKGROUND

Irritable bowel syndrome (IBS) is a functional gastrointestinal condition marked by chronic bowel pain or discomfort, as well as changes in abdominal motility. Despite its worldwide prevalence and clinical impact, the cause of IBS is unknown. Inflammation could play a fundamental role in the development of IBS. The aim of this study was to examine whether pentoxifylline, a competitive nonselective phosphodiesterase inhibitor, is useful in alleviating abdominal pain in IBS patients treated with mebeverine.

METHODS

A randomized, controlled, and prospective clinical study that included 50 outpatients who met the inclusion criteria for IBS. Patients are allocated randomly into two groups (n = 25). Group 1 (mebeverine group) received mebeverine 135 mg three times daily (t.i.d) for three months. Group 2 (pentoxifylline group) received mebeverine 135 mg t.i.d and pentoxifylline 400 mg two times daily for three months. Patients were assessed by a gastroenterologist at baseline and three months after the medication had been started. The serum levels of interleukin-6, interleukin-8 and tumor necrosis factor-alpha, fecal Neutrophil Gelatinase Associated Lipocalin (NGAL), and fecal myeloperoxidase were measured at the start and after three months of therapy. The Numeric Pain Rating scale (NRS) was assessed at baseline and after therapy.

RESULTS

the pentoxifylline group showed a significant decrease in the level of measured biomarkers and a significant decrease in NRS.

CONCLUSION

Pentoxifylline could be a promising adjuvant anti-inflammatory drug in the treatment of abdominal pain in IBS patients treated with mebeverine.

DSS-induced inflammation in the colon drives a proinflammatory signature in the brain that is ameliorated by prophylactic treatment with the S100A9 inhibitor paquinimod

Background

Inflammatory bowel disease (IBD) is established to drive pathological sequelae in organ systems outside the intestine, including the central nervous system (CNS). Many patients exhibit cognitive deficits, particularly during disease flare. The connection between colonic inflammation and neuroinflammation remains unclear and characterization of the neuroinflammatory phenotype in the brain during colitis is ill-defined.

Methods

Transgenic mice expressing a bioluminescent reporter of active caspase-1 were treated with 2% dextran sodium sulfate (DSS) for 7 days to induce acute colitis, and colonic, systemic and neuroinflammation were assessed. In some experiments, mice were prophylactically treated with paquinimod (ABR-215757) to inhibit S100A9 inflammatory signaling. As a positive control for peripheral-induced neuroinflammation, mice were injected with lipopolysaccharide (LPS). Colonic, systemic and brain inflammatory cytokines and chemokines were measured by cytokine bead array (CBA) and Proteome profiler mouse cytokine array. Bioluminescence was quantified in the brain and caspase activation was confirmed by immunoblot. Immune cell infiltration into the CNS was measured by flow cytometry, while light sheet microscopy was used to monitor changes in resident microglia localization in intact brains during DSS or LPS-induced neuroinflammation. RNA sequencing was performed to identify transcriptomic changes occurring in the CNS of DSS-treated mice. Expression of inflammatory biomarkers were quantified in the brain and serum by qRT-PCR, ELISA and WB.

Results

DSS-treated mice exhibited clinical hallmarks of colitis, including weight loss, colonic shortening and inflammation in the colon. We also detected a significant increase in inflammatory cytokines in the serum and brain, as well as caspase and microglia activation in the brain of mice with ongoing colitis. RNA sequencing of brains isolated from DSS-treated mice revealed differential expression of genes involved in the regulation of inflammatory responses. This inflammatory phenotype was similar to the signature detected in LPS-treated mice, albeit less robust and transient, as inflammatory gene expression returned to baseline following cessation of DSS. Pharmacological inhibition of S100A9, one of the transcripts identified by RNA sequencing, attenuated colitis severity and systemic and neuroinflammation.

Conclusions

Our findings suggest that local inflammation in the colon drives systemic inflammation and neuroinflammation, and this can be ameliorated by inhibition of the S100 alarmin, S100A9.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02317-6.

Dietary Modulation Alters Susceptibility to Listeria monocytogenes and Salmonella Typhimurium with or without a Gut Microbiota

Food safety has considerably improved worldwide, yet infections with foodborne human enteric pathogens, such as Listeria spp. and Salmonella spp., still cause numerous hospitalizations and fatalities. Since dietary alterations, including fiber deficiency, might impact the colonization resistance mediated by the gut microbiome, studying the diet-microbiome-pathogen axis holds promise in further understanding the pathogenesis mechanisms. Using a gnotobiotic mouse model containing a 14-member synthetic human gut microbiota (14SM), we have previously shown that dietary fiber deprivation promotes proliferation of mucin-degrading bacteria, leading to a microbiome-mediated erosion of the colonic mucus barrier, which results in an increased susceptibility toward the rodent enteric pathogen Citrobacter rodentium. Here, we sought to understand how a low-fiber diet affects susceptibility to Listeria monocytogenes and Salmonella enterica serovar Typhimurium by using our 14SM gnotobiotic mouse model in BALB/c and C57BL/6 mouse backgrounds, respectively. Intriguingly, and in contrast to our results with C. rodentium, we observed that depriving mice of dietary fiber protected them from infections with both pathogens, compared to mice fed a standard chow. The microbiome delayed the overall pathogenicity compared to the onset of disease observed in germfree control mice. Nevertheless, we observed the same effect of diet on germfree mice, suggesting that the susceptibility is directly driven by the diet itself even in the absence of the gut microbiome. Our study points out an important observation, namely, that dietary fiber plays a crucial role in either the host's susceptibility, the virulence of these pathogens, or both. It would be judicious to design and interpret future studies on this basis. IMPORTANCE The human enteric pathogens Listeria monocytogenes and Salmonella Typhimurium are employed as classical models in rodent hosts to understand the pathogenesis mechanisms of foodborne pathogens. Research in the past decade has stressed the importance of the gut microbial composition in modulating susceptibility to these pathogens. The results of our study-using gnotobiotic mice and germfree control animals-additionally suggest that the dietary fiber components can dominate the impact of enteropathogenic virulence over the pathogenicity-modulating properties of the gut microbiome. The significance of our research is that there is a need to carefully choose a certain chow when performing the enteropathogen-associated mouse experiments and to cautiously match the rodent diets when trying to replicate experiments across different laboratories. Finally, our data underscore the importance of using germfree control animals to study these pathogens, as our findings would have been prone to misinterpretation in the absence of these controls.

Gut-associated cGMP mediates colitis and dysbiosis in a mouse model of an activating mutation in GUCY2C

Activating mutations in receptor guanylyl cyclase C (GC-C), the target of gastrointestinal peptide hormones guanylin and uroguanylin, and bacterial heat-stable enterotoxins cause early-onset diarrhea and chronic inflammatory bowel disease (IBD). GC-C regulates ion and fluid secretion in the gut via cGMP production and activation of cGMP-dependent protein kinase II. We characterize a novel mouse model harboring an activating mutation in Gucy2c equivalent to that seen in an affected Norwegian family. Mutant mice demonstrated elevated intestinal cGMP levels and enhanced fecal water and sodium content. Basal and linaclotide-mediated small intestinal transit was higher in mutant mice, and they were more susceptible to DSS-induced colitis. Fecal microbiome and gene expression analyses of colonic tissue revealed dysbiosis, up-regulation of IFN-stimulated genes, and misregulation of genes associated with human IBD and animal models of colitis. This novel mouse model thus provides molecular insights into the multiple roles of intestinal epithelial cell cGMP, which culminate in dysbiosis and the induction of inflammation in the gut.

Comprehensive review of lipocalin 2-mediated effects in lung inflammation

Lipocalin-2 (LCN2) is an inflammatory mediator best known for its role as an innate acute-phase protein. LCN2 mediates the innate immune response to pathogens by sequestering iron, thereby inhibiting pathogen growth. Although LCN2 and its bacteriostatic properties are well studied, other LCN2 functions in the immune response to inflammatory stimuli are less well understood, such as its role as a chemoattractant and involvement in the regulation of cell migration and apoptosis. In the lungs, most studies thus far investigating the role of LCN2 in the immune response have looked at pathogenic inflammatory stimuli. Here, we compile data that explore the role of LCN2 in the immune response to various inflammatory stimuli in an effort to differentiate between protective versus detrimental roles of LCN2.

A Central Role for Atg5 in Microbiota-Dependent Foxp3+ RORγt+ Treg Cell Preservation to Maintain Intestinal Immune Homeostasis

Autophagy is an evolutionary conserved catabolic pathway that ensures the degradation of intracellular components. The autophagic pathway is regulated by autophagy-related (Atg) proteins that govern formation of double-membraned vesicles called autophagosomes. Autophagy deficiency in regulatory T (Treg) cells leads to increased apoptosis of these cells and to the development of autoimmune disorders, predominantly characterized by intestinal inflammation. Recently, RORγt-expressing Treg cells have been identified as key regulators of gut homeostasis, preventing intestinal immunopathology. To study the role of autophagy in RORγt⁺ Foxp3⁺ Treg cells, we generated mice lacking the essential component of the core autophagy machinery Atg5 in Foxp3⁺ cells. Atg5 deficiency in Treg cells led to a predominant intestinal inflammation. While Atg5-deficient Treg cells were reduced in peripheral lymphoid organs, the intestinal RORγt⁺ Foxp3⁺ subpopulation of Treg cells was most severely affected. Our data indicated that autophagy is essential to maintain the intestinal RORγt⁺ Foxp3⁺ Treg population, thereby protecting the mice from gut inflammatory disorders.

Prophylactic Administration of a Bacteriophage Cocktail Is Safe and Effective in Reducing Salmonella enterica Serovar Typhimurium Burden in Vivo

Nontyphoidal Salmonella bacteria are the causative agent of salmonellosis, which accounts for the majority of foodborne illness of bacterial etiology in humans. Here, we demonstrate the safety and efficacy of the prophylactic administration of a bacteriophage preparation termed FOP (foodborne outbreak pill), which contains lytic phages targeting Salmonella (SalmoFresh phage cocktail), Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes, for lowering Salmonella burdens in OMM¹² gnotobiotic mice. Prophylactic administration of FOP significantly reduced the levels of Salmonella in feces and in intestinal sections compared to the levels in controls. Moreover, the overall symptoms of the disease were also considerably lessened. Dose-dependent administration of FOP showed that phage amplification reached similarly high levels in less than 48 h independent of dose. In addition, 16S rRNA gene analysis showed that FOP did not alter the intestinal microbiota of healthy OMM¹² mice and reduced microbiota perturbations induced by Salmonella. FOP maintained its full potency against Salmonella in comparison to that of SalmoFresh, its Salmonella-targeting component phages alone. Altogether, the data support that preventive administration of FOP may offer a safe and effective approach for reducing the risk of foodborne infections caused by Salmonella and, potentially, other foodborne bacteria (namely, STEC and L. monocytogenes) targeted by the FOP preparation.

IMPORTANCE Foodborne bacterial infections cause worldwide economic loss. During an epidemic, the use of antibiotics to slow down the spread of the disease is not recommended because of their side effects on the resident microbiota and the selection of antibiotic-resistant bacteria. Here, we investigated the potential for the prophylactic administration of bacteriophages (viruses infecting bacteria) to reduce the burden of Salmonella in vivo using mice colonized by a synthetic microbiota. We found that the repeated administration of bacteriophages was safe and efficient in lowering the Salmonella burden. Perturbations of the microbiota by the Salmonella infection were also reduced when mice received bacteriophages. Altogether, these data support the use of bacteriophages as a prophylactic intervention to lower the spread of foodborne epidemics.

Effect of Advanced Glycation End-Products and Excessive Calorie Intake on Diet-Induced Chronic Low-Grade Inflammation Biomarkers in Murine Models

Chronic Low-Grade Inflammation (CLGI) is a non-overt inflammatory state characterized by a continuous activation of inflammation mediators associated with metabolic diseases. It has been linked to the overconsumption of Advanced Glycation End-Products (AGEs), and/or macronutrients which lead to an increase in local and systemic pro-inflammatory biomarkers in humans and animal models. This review provides a summary of research into biomarkers of diet-induced CLGI in murine models, with a focus on AGEs and obesogenic diets, and presents the physiological effects described in the literature. Diet-induced CLGI is associated with metabolic endotoxemia, and/or gut microbiota remodeling in rodents. The mechanisms identified so far are centered on pro-inflammatory axes such as the interaction between AGEs and their main receptor AGEs (RAGE) or increased levels of lipopolysaccharide. The use of murine models has helped to elucidate the local and systemic expression of CLGI mediators. These models have enabled significant advances in identification of diet-induced CLGI biomarkers and resultant physiological effects. Some limitations on the translational (murine → humans) use of biomarkers may arise, but murine models have greatly facilitated the testing of specific dietary components. However, there remains a lack of information at the whole-organism level of organization, as well as a lack of consensus on the best biomarker for use in CLGI studies and recommendations as to future research conclude this review.

Tolerogenic Dendritic Cells Shape a Transmissible Gut Microbiota That Protects From Metabolic Diseases

Excess chronic contact between microbial motifs and intestinal immune cells is known to trigger a low-grade inflammation involved in many pathologies such as obesity and diabetes. The important skewing of intestinal adaptive immunity in the context of diet-induced obesity (DIO) is well described, but how dendritic cells (DCs) participate in these changes is still poorly documented. To address this question, we challenged transgenic mice with enhanced DC life span and immunogenicity (DC^hBcl-2 mice) with a high-fat diet. Those mice display resistance to DIO and metabolic alterations. The DIO-resistant phenotype is associated with healthier parameters of intestinal barrier function and lower intestinal inflammation. DC^hBcl-2 DIO-resistant mice demonstrate a particular increase in tolerogenic DC numbers and function, which is associated with strong intestinal IgA, T helper 17, and regulatory T-cell immune responses. Microbiota composition and function analyses reveal that the DC^hBcl-2 mice microbiota is characterized by lower immunogenicity and an enhanced butyrate production. Cohousing experiments and fecal microbial transplantations are sufficient to transfer the DIO resistance status to wild-type mice, demonstrating that maintenance of DCs' tolerogenic ability sustains a microbiota able to drive DIO resistance. The tolerogenic function of DCs is revealed as a new potent target in metabolic disease management.

Nr4A1 modulates inflammation-associated intestinal fibrosis and dampens fibrogenic signaling in myofibroblasts

Intestinal fibrosis is a common complication of the inflammatory bowel diseases (IBDs), contributing to tissue stiffening and luminal narrowing. Human nuclear receptor 4A 1 (NR4A1) was previously reported to regulate mesenchymal cell function and dampen fibrogenic signaling. NR4A1 gene variants are associated with IBD risk, and it has been shown to regulate intestinal inflammation. Here, we tested the hypothesis that NR4A1 acts as a negative regulator of intestinal fibrosis through regulating myofibroblast function. Using the SAMP1/YitFc mouse, we tested whether two pharmacological agents known to enhance NR4A1 signaling, cytosporone B (Csn-B) or 6-mercaptopurine (6-MP), could reduce fibrosis. We also used the dextran sulfate sodium (DSS) model of colitis and assessed the magnitude of colonic fibrosis in mouse nuclear receptor 4A 1 (Nr4a1^-/-) and their wild-type littermates (Nr4a1^+/+). Lastly, intestinal myofibroblasts isolated from Nr4a1^-/- and Nr4a1^+/+ mice or primary human intestinal myofibroblasts were stimulated with transforming growth factor-β1 (TGF-β1), in the presence or absence of Csn-B or 6-MP, and proliferation and ECM gene expression assessed. Csn-B or 6-MP treatment significantly reduced ileal thickness, collagen, and overall ECM content in SAMP1/YitFc mice. This was associated with a reduction in proliferative markers within the mesenchymal compartment. Nr4a1^-/- mice exposed to DSS exhibited increased colonic thickening and ECM content. Nr4a1^-/- myofibroblasts displayed enhanced TGF-β1-induced proliferation. Furthermore, Csn-B or 6-MP treatment was antiproliferative in Nr4a1^+/+ but not Nr4a1^-/- cells. Lastly, activating NR4A1 in human myofibroblasts reduced TGF-β1-induced collagen deposition and fibrosis-related gene expression. Our data suggest that NR4A1 can attenuate fibrotic processes in intestinal myofibroblasts and could provide a valuable clinical target to treat inflammation-associated intestinal fibrosis.NEW & NOTEWORTHY Fibrosis and increased muscle thickening contribute to stricture formation and intestinal obstruction, a complication that occurs in 30%-50% of patients with CD within 10 yr of disease onset. More than 50% of those who undergo surgery to remove the obstructed bowel will experience stricture recurrence. To date, there are no drug-based approaches approved to treat intestinal strictures. In the current submission, we identify NR4A1 as a novel target to treat inflammation-associated intestinal fibrosis.

Lipocalin 2 Deficiency Restrains Aging-Related Reshaping of Gut Microbiota Structure and Metabolism

Gut microbiota modulate age-associated changes in metabolism, innate immune responses, and cognitive function. However, the involvement of host factors in the regulation of age-dependent gut microbial structure and intestinal inflammation is largely unknown. Lipocalin 2 (Lcn2) has previously been identified as an adipocytokine and characterized as an important regulator of diet-induced obesity and inflammation. Previous studies have shown that Lcn2 plays a role in high fat diet-induced reshaping of gut microbiota and intestinal inflammation. However, the role of Lcn2 in the regulation of aging-related reshaping of gut microbiota is unclear. Herein, we demonstrate that fecal levels of Lcn2 are reduced during aging. Age reshaped gut microbiota composition in wild-type (WT) mice. Interestingly, Lcn2 deficiency diminished this effect of aging in Lcn2 knockout (LKO) mice, leading to decreased bacterial diversity and increased Firmicutes to Bacteroidetes (F to B) ratio. Specifically, we identified 16 bacteria at the family level that were differentially abundant between WT and LKO mice at old age. Several health-promoting bacteria, including SCFA-producing bacteria, were significantly less prevalent in old LKO mice compared to WT mice, indicating that Lcn2 deficiency shifts the aging-related gut microbial community towards an unhealthy population and lowers microbial butyrate production. Our results provide a line of evidence that Lcn2 plays a role in the control of aging-related reshaping of gut microbiota composition and metabolites.

Prenatal maternal infection promotes tissue-specific immunity and inflammation in offspring

The immune system has evolved in the face of microbial exposure. How maternal infection experienced at distinct developmental stages shapes the offspring immune system remains poorly understood. Here, we show that during pregnancy, maternally restricted infection can have permanent and tissue-specific impacts on offspring immunity. Mechanistically, maternal interleukin-6 produced in response to infection can directly impose epigenetic changes on fetal intestinal epithelial stem cells, leading to long-lasting impacts on intestinal immune homeostasis. As a result, offspring of previously infected dams develop enhanced protective immunity to gut infection and increased inflammation in the context of colitis. Thus, maternal infection can be coopted by the fetus to promote long-term, tissue-specific fitness, a phenomenon that may come at the cost of predisposition to inflammatory disorders.

IL-10 Receptor Neutralization-Induced Colitis in Mice: A Comprehensive Guide

Interleukin-10 (IL-10) and its receptor (IL-10R) have been foremost targets to understand inflammatory bowel disease (IBD) pathogenesis. For the past several decades, IL-10-deficient (Il10^-/- ) mice were considered one of the best models to study immune-mediated colitis. Several physiologic limitations with this model, e.g., delayed and varied disease onset, have hindered investigators in testing new clinical therapies for IBD. In this article, we provide comprehensive guidance for using anti-IL-10R monoclonal antibody (αIL-10R mAb) neutralization as a superior alternative model to study IBD. This article describes the feasibility of using αIL-10R mAb to induce chronic colitis (within 4 weeks), perform time-dependent mechanistic studies, and assess the efficacy of IBD therapeutics. This article also delineates protocols for in-house assays to critically assess colitis and associated inflammatory parameters. Overall, we underscore αIL-10R mAb neutralization as a relevant immune-mediated murine colitis model to study human Crohn's disease. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Induction of chronic colitis in mice via αIL-10R mAb neutralization Basic Protocol 2: Biochemical evaluation of αIL-10R mAb neutralization-induced chronic colitis Support Protocol 1: Stool analysis and scoring Support Protocol 2: Swiss roll method.

Mouse Models of Intestinal Fibrosis

Mouse models are essential for investigation of underlying disease mechanisms that drive intestinal fibrosis, as well as assessment of potential therapeutic approaches to either prevent or resolve fibrosis. Here we describe several common mouse models of intestinal inflammation and fibrosis, including chemically driven colitis models, a bacterially triggered colitis model, and spontaneous intestinal inflammation in genetically susceptible mouse strains. Detailed protocols are provided for dextran sodium sulfate (DSS) colitis, 2,4,6-trinitro-benzene sulfonic acid (TNBS) colitis, adherent-invasive Escherichia coli (AIEC)-triggered colitis, the interleukin-10 knockout (IL-10KO) mouse model of spontaneous colitis, and the SAMP/YitFc model of spontaneous ileocolitis.

Association of lipocalin-2 and low-density lipoprotein receptor-related protein-1 (LRP1) with biomarkers of environmental enteric dysfunction (EED) among under 2 children in Bangladesh: results from a community-based intervention study

Background

Environmental enteric dysfunction (EED) is thought to occur from persistent intestinal inflammation. Studies also revealed the association of lipocalin-2 (LCN2) and low-density lipoprotein receptor-related protein-1 (LRP1) with intestinal inflammation. Therefore, we intended to explore the relationship of LCN2 and LRP1 with gut inflammation and biomarkers of EED in Bangladeshi malnourished children.

Methods

A total of 222 children (length-for-age z-score (LAZ) <-1) aged 12-18 months were enrolled in this study in a cross-sectional manner. Among the participants, 115 were stunted (LAZ <-2) and 107 were at risk of being stunted (LAZ -1 to -2) children. Plasma and faecal biomarkers were measured using ELISA. Spearman's rank correlation was done to see the correlation among LCN2, LRP1 and biological biomarkers.

Results

LCN2 correlates positively with myeloperoxidase (r=0.19, p=0.005), neopterin (r=0.20, p=0.004), calprotectin (r=0.3, p=0.0001), Reg1B (r=0.20, p=0.003) and EED score (r=0.20, p=0.003). Whereas, LRP1 correlates negatively with myeloperoxidase (r = -0.18, p=0.006), neopterin (r = -0.30, p=0.0001), alpha-1-antitrypsin (r = -0.18, p=0.006), Reg1B (r=-0.2, p=0.003) and EED score (r = -0.29, p=0.0001).

Conclusions

Our findings imply that LCN2 might be a promising biomarker to predict gut inflammation and EED. Whereas, increased level of LRP1 may contribute to alleviating intestinal inflammation.

The Role of Common Solvents against Pseudomonas aeruginosa-Induced Pathogenicity in a Murine Burn Site Infection Model

Dimethyl sulfoxide (DMSO) and polyethylene glycols (PEGs) are frequently used as potent excipients in pharmaceutical formulations. However, these agents also have an interesting antimicrobial and anti-inflammatory profile that could interfere with the efficacy testing of anti-infective compounds when the latter are solubilized in DMSO or PEGs. Here, we demonstrate the antimicrobial and anti-inflammatory effects of DMSO-PEG400 in a murine Pseudomonas aeruginosa infection model, aiming to draw attention to the appropriate selection of solvents for difficult-to-solubilize anti-infectives. IMPORTANCE Our study demonstrates the antimicrobial and anti-inflammatory effects of the combination of DMSO and PEG400 against Pseudomonas aeruginosa in vitro and in vivo in a murine infection model of heightened intestinal permeability. The aim of this study is to draw attention to the appropriate selection of solvents for difficult-to-solubilize anti-infective compounds, to avoid interference with the assay or system tested. This is an extremely important consideration, since potential antimicrobial and anti-inflammatory effects of the solvent vehicle are detrimental to research studies on the efficacy of new anti-infective agents, given that the vehicle effect can mask the effect of the tested compounds. Our results can therefore be of great value to the scientific community, as they can guide researchers in the future to avoid this significant pitfall that can cost substantial amounts of money and valuable time during investigations of the effects of novel, difficult-to-solubilize antimicrobial compounds.

Lipocalin 2 stimulates bone fibroblast growth factor 23 production in chronic kidney disease

Bone-produced fibroblast growth factor 23 (FGF23) increases in response to inflammation and iron deficiency and contributes to cardiovascular mortality in chronic kidney disease (CKD). Neutrophil gelatinase-associated lipocalin (NGAL or lipocalin 2; LCN2 the murine homolog) is a pro-inflammatory and iron-shuttling molecule that is secreted in response to kidney injury and may promote CKD progression. We investigated bone FGF23 regulation by circulating LCN2. At 23 weeks, Col4a3^KO mice showed impaired kidney function, increased levels of kidney and serum LCN2, increased bone and serum FGF23, anemia, and left ventricular hypertrophy (LVH). Deletion of Lcn2 in CKD mice did not improve kidney function or anemia but prevented the development of LVH and improved survival in association with marked reductions in serum FGF23. Lcn2 deletion specifically prevented FGF23 elevations in response to inflammation, but not iron deficiency or phosphate, and administration of LCN2 increased serum FGF23 in healthy and CKD mice by stimulating Fgf23 transcription via activation of cAMP-mediated signaling in bone cells. These results show that kidney-produced LCN2 is an important mediator of increased FGF23 production by bone in response to inflammation and in CKD. LCN2 inhibition might represent a potential therapeutic approach to lower FGF23 and improve outcomes in CKD.

Dietary nanoparticles alter the composition and function of the gut microbiota in mice at dose levels relevant for human exposure

BACKGROUND

Nanotechnologies provide new opportunities for improving the safety, quality, shelf life, flavor and appearance of foods. The most common nanoparticles (NPs) in human diet are silver metal, mainly present in food packaging and appliances, and silicon and titanium dioxides used as additives. The rapid development and commercialization of consumer products containing these engineered NPs is, however, not well supported by appropriate toxicological studies and risk assessment. Local and systemic toxicity and/or disruption of the gut microbiota (GM) have already been observed after oral administration of NPs in experimental animals, but results are not consistent and doses used were often much higher than the estimated human intakes. In view of the strong evidence linking alterations of the GM to cardiometabolic (CM) diseases, we hypothesized that dietary NPs might disturb this GM-CM axis.

MATERIALS AND METHODS

We exposed male C57BL/6JRj mice (n = 13 per dose group) to dietary NPs mixed in food pellets at doses relevant for human exposure: Ag (0, 4, 40 or 400 μg/kg pellet), SiO2 (0, 0.8, 8 and 80 mg/kg pellet) or TiO2 (0, 0.4, 4 or 40 mg/kg pellet). After 24 weeks of exposure, we assessed effects on the GM and CM health (n = 8 per dose group). The reversibility of the effects was examined after 8 additional weeks without NPs exposure (recovery period, n ≤ 5 per dose group).

RESULTS

No overt toxicity was recorded. The GM β-diversity was dose-dependently disrupted by the three NPs, and the bacterial short chain fatty acids (SCFAs) were dose-dependently reduced after the administration of SiO2 and TiO2 NPs. These effects disappeared completely or partly after the recovery period, strengthening the association with dietary NPs. We did not observe atheromatous disease or glucose intolerance after NP exposure. Instead, dose-dependent decreases in the expression of IL-6 in the liver, circulating triglycerides (TG) and urea nitrogen (BUN) were recorded after administration of the NPs.

CONCLUSION

We found that long-term oral exposure to dietary NPs at doses relevant for estimated human intakes disrupts the GM composition and function. These modifications did not appear associated with atheromatous or deleterious metabolic outcomes.

Geographic differences in gut microbiota composition impact susceptibility to enteric infection

Large-scale studies of human gut microbiomes have revealed broad differences in composition across geographically distinct populations. Yet, studies examining impacts of microbiome composition on various health outcomes typically focus on single populations, posing the question of whether compositional differences between populations translate into differences in susceptibility. Using germ-free mice humanized with microbiome samples from 30 donors representing three countries, we observe robust differences in susceptibility to Citrobacter rodentium, a model for enteropathogenic Escherichia coli infections, according to geographic origin. We do not see similar responses to Listeria monocytogenes infections. We further find that cohousing the most susceptible and most resistant mice confers protection from C. rodentium infection. This work underscores the importance of increasing global participation in microbiome studies related to health outcomes. Diverse cohorts are needed to identify both population-specific responses to specific microbiome interventions and to achieve broader-reaching biological conclusions that generalize across populations.

Food colorants metabolized by commensal bacteria promote colitis in mice with dysregulated expression of interleukin-23

Both genetic predisposition and environmental factors appear to play a role in inflammatory bowel disease (IBD) development. Genetic studies in humans have linked the interleukin (IL)-23 signaling pathway with IBD, but the environmental factors contributing to disease have remained elusive. Here, we show that the azo dyes Red 40 and Yellow 6, the most abundant food colorants in the world, can trigger an IBD-like colitis in mice conditionally expressing IL-23, or in two additional animal models in which IL-23 expression was augmented. Increased IL-23 expression led to generation of activated CD4⁺ T cells that expressed interferon-γ and transferred disease to mice exposed to Red 40. Colitis induction was dependent on the commensal microbiota promoting the azo reduction of Red 40 and generation of a metabolite, 1-amino-2-naphthol-6-sulfonate sodium salt. Together these findings suggest that specific food colorants represent novel risk factors for development of colitis in mice with increased IL-23 signaling.

Functions and potential of lipocalin-2 as fecal biomarker for acute gastrointestinal infections (review of literature)

Despite the visible progress in reducing morbidity and mortality from intestinal infections and acute diarrhea associated with them, especially in childhood, the problem of their diagnosis and treatment remains relevant. The article discusses the structure, function and application of lipocalin-2 in infectious diseases as a non-invasive biomarker of bacterial inflammation in the intestine.

Raising the 'Good' Oxidants for Immune Protection

Redox medicine is a new therapeutic concept targeting reactive oxygen species (ROS) and secondary reaction products for health benefit. The concomitant function of ROS as intracellular second messengers and extracellular mediators governing physiological redox signaling, and as damaging radicals instigating or perpetuating various pathophysiological conditions will require selective strategies for therapeutic intervention. In addition, the reactivity and quantity of the oxidant species generated, its source and cellular location in a defined disease context need to be considered to achieve the desired outcome. In inflammatory diseases associated with oxidative damage and tissue injury, ROS source specific inhibitors may provide more benefit than generalized removal of ROS. Contemporary approaches in immunity will also include the preservation or even elevation of certain oxygen metabolites to restore or improve ROS driven physiological functions including more effective redox signaling and cell-microenvironment communication, and to induce mucosal barrier integrity, eubiosis and repair processes. Increasing oxidants by host-directed immunomodulation or by exogenous supplementation seems especially promising for improving host defense. Here, we summarize examples of beneficial ROS in immune homeostasis, infection, and acute inflammatory disease, and address emerging therapeutic strategies for ROS augmentation to induce and strengthen protective host immunity.