Interleukin-22 suppresses major histocompatibility complex II in mucosal epithelial cells

Major histocompatibility complex (MHC) II is dynamically expressed on mucosal epithelial cells and is induced in response to inflammation and parasitic infections, upon exposure to microbiota, and is increased in chronic inflammatory diseases. However, the regulation of epithelial cell-specific MHC II during homeostasis is yet to be explored. We discovered a novel role for IL-22 in suppressing epithelial cell MHC II partially via the regulation of endoplasmic reticulum (ER) stress, using animals lacking the interleukin-22-receptor (IL-22RA1), primary human and murine intestinal and respiratory organoids, and murine models of respiratory virus infection or with intestinal epithelial cell defects. IL-22 directly downregulated interferon-γ-induced MHC II on primary epithelial cells by modulating the expression of MHC II antigen A α (H2-Aα) and Class II transactivator (Ciita), a master regulator of MHC II gene expression. IL-22RA1-knockouts have significantly higher MHC II expression on mucosal epithelial cells. Thus, while IL-22-based therapeutics improve pathology in chronic disease, their use may increase susceptibility to viral infections.

MUC13 Cell Surface Mucin Limits Salmonella Typhimurium Infection by Protecting the Mucosal Epithelial Barrier

BACKGROUND & AIMS

MUC13 cell surface mucin is highly expressed on the mucosal surface throughout the intestine, yet its role against bacterial infection is unknown. We investigated how MUC13 impacts Salmonella typhimurium (S Tm) infection and elucidated its mechanisms of action.

METHODS

Muc13-/- and wild-type littermate mice were gavaged with 2 isogenic strains of S Tm after pre-conditioning with streptomycin. We assessed clinical parameters, cecal histology, local and systemic bacterial load, and proinflammatory cytokines after infection. Cecal enteroids and epithelial cell lines were used to evaluate the mechanism of MUC13 activity after infection. The interaction between bacterial SiiE and MUC13 was assessed by using siiE-deficient Salmonella.

RESULTS

S Tm-infected Muc13-/- mice had increased disease activity, histologic damage, and higher local and systemic bacterial loads. Mechanistically, we found that S Tm binds to MUC13 through its giant SiiE adhesin and that MUC13 acts as a pathogen-binding decoy shed from the epithelial cell surface after pathogen engagement, limiting bacterial invasion. In addition, MUC13 reduces epithelial cell death and intestinal barrier breakdown by enhancing nuclear factor kappa B signaling during infection, independent of its decoy function.

CONCLUSIONS

We show for the first time that MUC13 plays a critical role in antimicrobial defense against pathogenic S Tm at the intestinal mucosal surface by both acting as a releasable decoy limiting bacterial invasion and reducing pathogen-induced cell death. This further implicates the cell surface mucin family in mucosal defense from bacterial infection.

Pancreatic Interleukin-22 Receptor Signaling is Critical in Maintaining Beta-Cell Insulin Production and is Hepatoprotective

We discovered that the cytokine interleukin-22 (IL-22) is an efficient natural inhibitor of cellular stress and exogenous IL-22 improved insulin quality in pancreatic β-cells in preclinical models of Type 2 diabetes. Importantly, IL-22 completely restored glucose tolerance, suppressed fasting hyperinsulinemia/hyperproinsulinemia, and restored insulin sensitivity in obese animals. Moreover, metabolic improvements were accompanied by significant improvements in circulating triglycerides, liver function (AST:ALT ratio) and a reduction in hepatic lipid accumulation. Whilst the IL-22 receptor, IL-22RA1 is highly expressed in the pancreas and liver, its endogenous role in these tissues remains elusive. To explore this, we generated tissue specific IL-22ra1 knockout mice lacking the receptor in pancreatic β-cells (Il-22ra1fl/fl x Ins2Cre: IL-22ra1β-cell−/−) and hepatocytes (Il-22ra1fl/fl x AlbCre: IL-22ra1Hep−/−). We assessed their metabolic phenotype including glycemic control, hepatic lipid accumulation, and hepatic markers of cellular stress, lipid, and glucose metabolism with age or with obesity. We discovered that IL-22ra1β-cell−/− animals developed hyperglycemia with age and had defective insulin secretion, which was exacerbated when on a high fat diet. Interestingly, they also had a significant increase in markers of hepatic inflammation and cellular stress. In conclusion we demonstrate, for the first time, that local endogenous IL-22 secretion in pancreatic β-cells maintains insulin biosynthesis. Moreover, our work highlights the importance of the pancreatic-β-cell-liver axis as the absence of pancreatic IL-22ra1 signaling leads to a marked increase in liver inflammation and cellular stress.

Secreted NF-κB suppressive microbial metabolites modulate gut inflammation

Emerging evidence suggests that microbiome-host crosstalk regulates intestinal immune activity and predisposition to inflammatory bowel disease (IBD). NF-κB is a master regulator of immune function and a validated target for the treatment of IBD. Here, we identify five Clostridium strains that suppress immune-mediated NF-κB activation in epithelial cell lines, PBMCs, and gut epithelial organoids from healthy human subjects and patients with IBD. Cell-free culture supernatant from Clostridium bolteae AHG0001 strain, but not the reference C. bolteae BAA-613 strain, suppresses inflammatory responses and endoplasmic reticulum stress in gut epithelial organoids derived from Winnie mice. The in vivo responses to Clostridium bolteae AHG0001 and BAA-613 mirror the in vitro activity. Thus, using our in vitro screening of bacteria capable of suppressing NF-κB in the context of IBD and using an ex vivo organoid-based approach, we identify a strain capable of alleviating colitis in a relevant pre-clinical animal model of IBD.

Gut microbiota shape the inflammatory response in mice with an epithelial defect

Intestinal epithelial cell endoplasmic reticulum (ER) stress has been implicated in intestinal inflammation. It remains unclear whether ER stress is an initiator of or a response to inflammation. Winnie mice, carrying a Muc2 gene mutation resulting in intestinal goblet cell ER stress, develop spontaneous colitis with a depleted mucus barrier and increased bacterial translocation. This study aims to determine whether the microbiota was required for the development of Winnie colitis, and whether protein misfolding itself can initiate inflammation directly in absence of the microbiota. To assess the role of microbiota in driving Winnie colitis, WT and Winnie mice on the same background were rederived into the germ-free facility and housed in the Trexler-type soft-sided isolators. The colitis phenotype of these mice was assessed and compared to WT and Winnie mice housed within a specific pathogen-free facility. We found that Winnie colitis was substantially reduced but not abolished under germ-free conditions. Expression of inflammatory cytokine genes was reduced but several chemokines remained elevated in absence of microbiota. Concomitantly, ER stress was also diminished, although mucin misfolding persisted. RNA-Seq revealed that Winnie differentiated colon organoids have decreased expression of the negative regulators of the inflammatory response compared to WT. This data along with the increase in Mip2a chemokine expression, suggests that the epithelial cells in the Winnie mice are more responsive to stimuli. Moreover, the data demonstrate that intestinal epithelial intrinsic protein misfolding can prime an inflammatory response without initiating the unfolded protein response in the absence of the microbiota. However, the microbiota is necessary for the amplification of colitis in Winnie mice. Genetic predisposition to mucin misfolding in secretory cells initiates mild inflammatory signals. However, the inflammatory signal sets a forward-feeding cycle establishing progressive inflammation in the presence of microbiota.Abbreviations: Endoplasmic Reticulum: ER; Mucin-2: Muc-2; GF: Germ-Free; Inflammatory Bowel Disease: IBD.

Influence of the MUC1 Cell Surface Mucin on Gastric Mucosal Gene Expression Profiles in Response to Helicobacter pylori Infection in Mice

The cell surface mucin MUC1 is an important host factor limiting Helicobacter pylori (H. pylori) pathogenesis in both humans and mice by providing a protective barrier and modulating mucosal epithelial and leukocyte responses. The aim of this study was to establish the time-course of molecular events in MUC1-modulated gene expression profiles in response to H. pylori infection in wild type (WT) and MUC1-deficient mice using microarray-determined mRNA expression, gene network analysis and Ingenuity Pathway Analysis (IPA). A time-course over the first 72 h of infection showed significantly higher mucosal loads of bacteria at 8 h of infection in Muc1^−/− mice compared with WT, confirming its importance in the early stages of infection (P = 0.0003). Microarray analysis revealed 266 differentially expressed genes at one or more time-points over 72 h in the gastric mucosa of Muc1^−/− mice compared with WT control using a threshold of 2-fold change. The SPINK1 pancreatic cancer canonical pathway was strongly inhibited in Muc1^−/− mice compared with WT at sham and 8 h infection (P = 6.08E-14 and P = 2.25 E-19, respectively) but potently activated at 24 and 72 h post-infection (P = 1.38E-22 and P = 5.87E-13, respectively). The changes in this pathway are reflective of higher expression of genes mediating digestion and absorption of lipids, carbohydrates, and proteins at sham and 8 h infection in the absence of MUC1, but that this transcriptional signature is highly down regulated as infection progresses in the absence of MUC1. Uninfected Muc1^−/− gastric tissue was highly enriched for expression of factors involved in lipid metabolism and 8 h infection further activated this network compared with WT. As infection progressed, a network of antimicrobial and anti-inflammatory response genes was more highly activated in Muc1^−/− than WT mice. Key target genes identified by time-course microarrays were independently validated using RT-qPCR. These results highlight the dynamic interplay between the host and H. pylori, and the role of MUC1 in host defense, and provide a general picture of changes in cellular gene expression modulated by MUC1 in a time-dependent manner in response to H. pylori infection.

Airway Mucus Hyperconcentration in Non-Cystic Fibrosis Bronchiectasis

Rationale: Non-cystic fibrosis bronchiectasis is characterized by airway mucus accumulation and sputum production, but the role of mucus concentration in the pathogenesis of these abnormalities has not been characterized.Objectives: This study was designed to: 1) measure mucus concentration and biophysical properties of bronchiectasis mucus; 2) identify the secreted mucins contained in bronchiectasis mucus; 3) relate mucus properties to airway epithelial mucin RNA/protein expression; and 4) explore relationships between mucus hyperconcentration and disease severity.Methods: Sputum samples were collected from subjects with bronchiectasis, with and without chronic erythromycin administration, and healthy control subjects. Sputum percent solid concentrations, total and individual mucin concentrations, osmotic pressures, rheological properties, and inflammatory mediators were measured. Intracellular mucins were measured in endobronchial biopsies by immunohistochemistry and gene expression. MUC5B (mucin 5B) polymorphisms were identified by quantitative PCR. In a replication bronchiectasis cohort, spontaneously expectorated and hypertonic saline-induced sputa were collected, and mucus/mucin concentrations were measured.Measurements and Main Results: Bronchiectasis sputum exhibited increased percent solids, total and individual (MUC5B and MUC5AC) mucin concentrations, osmotic pressure, and elastic and viscous moduli compared with healthy sputum. Within subjects with bronchiectasis, sputum percent solids correlated inversely with FEV₁ and positively with bronchiectasis extent, as measured by high-resolution computed tomography, and inflammatory mediators. No difference was detected in MUC5B rs35705950 SNP allele frequency between bronchiectasis and healthy individuals. Hypertonic saline inhalation acutely reduced non-cystic fibrosis bronchiectasis mucus concentration by 5%.Conclusions: Hyperconcentrated airway mucus is characteristic of subjects with bronchiectasis, likely contributes to disease pathophysiology, and may be a target for pharmacotherapy.

Efficient photoacoustic imaging using indocyanine green (ICG) loaded functionalized mesoporous silica nanoparticles

Photoacoustic (PA) imaging is gaining momentum due to its greater depth of field, low background, and 3D imaging capabilities. However, traditional PA imaging agents (e.g. dyes, quantum dots, etc.) are usually unstable in plasma and bind to serum proteins, and thus cleared rapidly. Because of this, the nanoparticle encapsulation of PA imaging agents is becoming increasingly popular. Therefore, the rational design of carrier nanoparticles for this purpose is necessary for strong imaging signal intensity, high biosafety, and precise targeting. Herein, we systematically evaluate the influence of the chemical and physical surface functionalization of mesoporous silica nanoparticles (MSNs) on the photo-stability, loading, release, and photoacoustic (PA) signal strength of the FDA approved small molecule contrast agent, indocyanine green (ICG). Chemical functionalization involved the modification of MSNs with silanes having amine (NH2) or phosphonate (PO3) terminal groups, whereas physical modifications were performed by capping the ICG loaded MSNs with lipid bilayer (LB) or layer-by-layer (LBL) polyelectrolyte coatings. The NH2-MSNs display the highest ICG mass loading capacity (16.5 wt%) with a limited release of ICG (5%) in PBS over 48 h, while PO3-MSNs only loaded ICG around 3.5 wt%. The physically modified MSNs (i.e. LBMSNs and LBLMSNs) were vacuum loaded resulting in approximately 9 wt% loading and less than 10% ICG release in 48 h. Pure ICG was highly photo-unstable and showed 20% reduction in photoluminescence (PL) within 3 h of exposure to 800 nm, while the ICG loaded onto functionalized MSNs did not photo-degrade. Among the tested formulations, NH2-MSNs and LBLMSNs presented 4-fold in vitro PA signal intensity enhancement at a 200 μg mL-1 equivalent ICG dose. Similar to the in vitro PA imaging, NH2-MSNs and LBLMSNs performed the best when subcutaneously injected into mouse cadavers with 1.29- and 1.43-fold PA signal enhancement in comparison to the pure ICG, respectively.

Lubrication by biomacromolecules: mechanisms and biomimetic strategies

Biomacromolecules play a key role in protecting human biointerfaces from friction and wear, and thus enable painless motion. Biomacromolecules give rise to remarkable tribological properties that researchers have been eager to emulate. In this review, we examine how molecules such as mucins, lubricin, hyaluronic acid and other components of biotribological interfaces provide a unique set of rheological and surface properties that leads to low friction and wear. We then highlight how researchers have used some of the features of biotribological contacts to create biomimetic systems. While the brush architecture of the glycosylated molecules present at biotribological interfaces has inspired some promising polymer brush systems, it is the recent advance in the understanding of synergistic interaction between biomacromolecules that is showing the most potential in producing surfaces with a high lubricating ability. Research currently suggests that no single biomacromolecule or artificial polymer successfully reproduces the tribological properties of biological contacts. However, by combining molecules, one can enhance their anchoring and lubricating capacity, thus enabling the design of surfaces for use in biomedical applications requiring low friction and wear.

Effect of MUC1 length polymorphisms on the NLRP3 inflammasome response of human macrophages

Mucin 1 is a cell-membrane associated mucin, expressed on epithelial and immune cells that helps protect against pathogenic infections. In humans, MUC1 is highly polymorphic, predominantly due to the presence of a variable number tandem repeat (VNTR) region in the extracellular domain that results in MUC1 molecules of typically either short or long length. A genetic link is known between these MUC1 polymorphisms and inflammation-driven diseases, although the mechanism is not fully understood. We previously showed that MUC1 on murine macrophages specifically restricts activation of the NLRP3 inflammasome, thereby repressing inflammation. This study evaluated the effect of MUC1 VNTR polymorphisms on activity of the NLRP3 inflammasome in human macrophages, finding that long MUC1 alleles correlated with increased IL-1β production following NLRP3 inflammasome activation. This indicates that the length of MUC1 can influence IL-1β production, thus providing the first evidence of an immune-modulatory role of MUC1 VNTR polymorphisms in human macrophages.

Fibre Intake Is Independently Associated with Increased Circulating Interleukin-22 in Individuals with Metabolic Syndrome

The positive effects of dietary fibre on gut barrier function and inflammation have not been completely elucidated. Mice studies show gut barrier disruption and diet-induced insulin resistance can be alleviated by cytokine interleukin-22 (IL-22). However, little is known about IL-22 in humans and its association with gut-beneficial nutrients like fibre. We investigated whether fibre intake was associated with circulating levels of IL-22 in 48 participants with metabolic syndrome (MetS). Bivariate analysis was used to explore associations between circulating IL-22, fibre intake, MetS factors, body composition, and cardiorespiratory fitness (peak oxygen uptake, V ˙ O2peak). Hierarchical multiple regression (HMR) was used to test the independent association of fibre intake with circulating IL-22, adjusting for variables correlated with IL-22. Circulating IL-22 was positively associated with fibre intake (rs = 0.393, p < 0.006). The HMR-adjusted model explained 40% of circulating IL-22 variability, and fibre intake significantly improved the prediction model by 8.4% (p < 0.022). Participants with fibre intake above median intake of 21.5 g/day had a significantly higher circulating IL-22 than the lower intake group (308.3 ± 454.4 vs. 69.0 ± 106.4 pg/mL, p < 0.019). Fibre intake is independently associated with increased circulating IL-22 in individuals with MetS. Findings warrant further investigations to evaluate whether changes in dietary fibre intake alter circulating IL-22, and its effects on health outcomes.

GRP78 expression in tumor and perinephric adipose tissue is not an optimal risk stratification marker for clear cell renal cell carcinoma

Objective

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer, which is difficult to treat and lacks a reliable prognostic marker. A previous study showed that the endoplasmic reticulum stress marker, glucose-regulated-protein-78 (GRP78), is a potential prognostic marker for ccRCC. The present study aimed to: (1) examine whether GRP78 was upregulated in ccRCC compared with matched non-neoplastic renal tissue; and (2) investigate whether GRP78 expression in ccRCC tissue or perinephric adipose tissue has any association with ccRCC aggressiveness.

Methods

A retrospective cross-sectional study of 267 patients who underwent nephrectomy for renal tumors between June 2013 and October 2017 was conducted at Princess Alexandra Hospital, Brisbane, Australia. Software-assisted quantification of average grey value of staining intensity (staining intensity method) and proportion of positive pixels (positive pixel method) was applied to measure expression of GRP78 in archived specimens of renal tumor tissues (n = 114), adjacent non-neoplastic renal tissues (n = 68), and perinephric adipose tissues (n = 60) in participants diagnosed with ccRCC.

Results

GRP78 was not upregulated in renal tumor tissue compared with paired normal renal tissue. In tumor tissue, GRP78 expression did not show any association with ccRCC aggressiveness using either quantification method. In adipose tissue, downregulation of GRP78 demonstrated poor correlation with increased probability of metastasis, with one unit increase in average grey value of GRP78 staining weakly correlating with a 17% increase in the odds ratio of metastasis (95% confidence interval: 0.99 to 1.38, p = 0.07).

Conclusion

GRP78 is not valuable as a risk stratification marker for ccRCC.

PPARγ is reduced in the airways of non-CF bronchiectasis subjects and is inversely correlated with the presence of Pseudomonas aeruginosa

BACKGROUND

Chronic airway inflammation in conditions such as cystic fibrosis (CF) and non-CF bronchiectasis is characterised by a predominant neutrophilic inflammatory response, commonly due to the presence of pathogenic bacteria such as Pseudomonas aeruginosa. We hypothesised that down-regulation of the anti-inflammatory nuclear transcription regulator peroxisome proliferator-activated receptor gamma (PPARγ in non-CF bronchiectasis subjects may explain why this exuberant neutrophilic inflammation is able to persist unchecked in the inflamed airway.

METHODS

PPARγ gene expression was assessed in bronchoalveolar lavage fluid (BAL) of 35 macrolide naïve non-CF bronchiectasis subjects and compared with that in 20 healthy controls. Human RNA was extracted from pelleted BAL and PPARγ expression was determined by reverse-transcription quantitative PCR. Bacterial DNA was extracted from paired induced sputum and total bacterial load was determined by 16S rRNA qPCR. Quantification of individual bacterial species was achieved by qPCR.

RESULTS

PPARγ expression was lower in subjects with non-CF bronchiectasis compared with healthy control subjects (control: 1.00, IQR 0.55-1.44, n = 20 vs. Bronchiectasis: 0.49, IQR 0.12-0.89; n = 35; p<0.001, Mann-Whitney U test). This lower PPARγ expression correlated negatively with Pseudomonas aeruginosa (r = -0.53, n = 31; p = 0.002). No significant association was seen between PPARγ and total bacterial levels or levels Haemophilus influenzae.

CONCLUSION

PPARγ is expressed in low levels in the airways of non-CF bronchiectasis subjects, despite an aggressive inflammatory response. This low level PPARγ expression is particularly associated with the presence of high levels of P. aeruginosa, and may represent an intrinsic link with this bacterial pathogen.

Oxidative and endoplasmic reticulum stress in respiratory disease

Oxidative stress and endoplasmic reticulum (ER) stress are related states that can occur in cells as part of normal physiology but occur frequently in diseases involving inflammation. In this article, we review recent findings relating to the role of oxidative and ER stress in the pathophysiology of acute and chronic nonmalignant diseases of the lung, including infections, cystic fibrosis, idiopathic pulmonary fibrosis and asthma. We also explore the potential of drugs targeting oxidative and ER stress pathways to alleviate disease.

Role of the unfolded protein response in determining the fate of tumor cells and the promise of multi-targeted therapies

Although there have been advances in our understanding of carcinogenesis and development of new treatments, cancer remains a common cause of death. Many regulatory pathways are incompletely understood in cancer development and progression, with a prime example being those related to the endoplasmic reticulum (ER). The pathological sequelae that arise from disruption of ER homeostasis are not well defined. The ER is an organelle that is responsible for secretory protein biosynthesis and the quality control of protein folding. The ER triggers an unfolded protein response (UPR) when misfolded proteins accumulate, and while the UPR acts to restore protein folding and ER homeostasis, this response can work as a switch to determine the death or survival of cells. The treatment of cancer with agents that target the UPR has shown promising outcomes. The UPR has wide crosstalk with other signaling pathways. Multi-targeted cancer therapies which target the intersections within signaling networks have shown synergistic tumoricidal effects. In the present review, the basic cellular and signaling pathways of the ER and UPR are introduced; then the crosstalk between the ER and other signaling pathways is summarized; and ultimately, the evidence that the UPR is a potential target for cancer therapy is discussed. Regulation of the UPR downstream signaling is a common therapeutic target for different tumor types. Tumoricidal effects achieved from modulating the UPR downstream signaling could be enhanced by phosphodiesterase 5 (PDE5) inhibitors. Largely untapped by Western medicine for cancer therapies are Chinese herbal medicines. This review explores and discusses the value of some Chinese herbal extracts as PDE5 inhibitors.

Enterococcus faecalis AHG0090 is a Genetically Tractable Bacterium and Produces a Secreted Peptidic Bioactive that Suppresses Nuclear Factor Kappa B Activation in Human Gut Epithelial Cells

Enterococcus faecalis is an early coloniser of the human infant gut and contributes to the development of intestinal immunity. To better understand the functional capacity of E. faecalis, we constructed a broad host range RP4 mobilizable vector, pEHR513112, that confers chloramphenicol resistance and used a metaparental mating approach to isolate E. faecalis AHG0090 from a fecal sample collected from a healthy human infant. We demonstrated that E. faecalis AHG0090 is genetically tractable and could be manipulated using traditional molecular microbiology approaches. E. faecalis AHG0090 was comparable to the gold-standard anti-inflammatory bacterium Faecalibacterium prausnitzii A2-165 in its ability to suppress cytokine-mediated nuclear factor kappa B (NF-κB) activation in human gut-derived LS174T goblet cell like and Caco-2 enterocyte-like cell lines. E. faecalis AHG0090 and F. prausnitzii A2-165 produced secreted low molecular weight NF-κB suppressive peptidic bioactives. Both bioactives were sensitive to heat and proteinase K treatments although the E. faecalis AHG0090 bioactive was more resilient to both forms of treatment. As expected, E. faecalis AHG0090 suppressed IL-1β-induced NF-κB-p65 subunit nuclear translocation and expression of the NF-κB regulated genes IL-6, IL-8 and CXCL-10. Finally, we determined that E. faecalis AHG0090 is distantly related to other commensal strains and likely encodes niche factors that support effective colonization of the infant gut.

Mucin gel assembly is controlled by a collective action of non-mucin proteins, disulfide bridges, Ca2+-mediated links, and hydrogen bonding

Mucus is characterized by multiple levels of assembly at different length scales which result in a unique set of rheological (flow) and mechanical properties. These physical properties determine its biological function as a highly selective barrier for transport of water and nutrients, while blocking penetration of pathogens and foreign particles. Altered integrity of the mucus layer in the small intestine has been associated with a number of gastrointestinal tract pathologies such as Crohn’s disease and cystic fibrosis. In this work, we uncover an intricate hierarchy of intestinal mucin (Muc2) assembly and show how complex rheological properties emerge from synergistic interactions between mucin glycoproteins, non-mucin proteins, and Ca²⁺. Using a novel method of mucus purification, we demonstrate the mechanism of assembly of Muc2 oligomers into viscoelastic microscale domains formed via hydrogen bonding and Ca²⁺-mediated links, which require the joint presence of Ca²⁺ ions and non-mucin proteins. These microscale domains aggregate to form a heterogeneous yield stress gel-like fluid, the macroscopic rheological properties of which are virtually identical to that of native intestinal mucus. Through proteomic analysis, we short-list potential protein candidates implicated in mucin assembly, thus paving the way for identifying the molecules responsible for the physiologically critical biophysical properties of mucus.

Infection's Sweet Tooth: How Glycans Mediate Infection and Disease Susceptibility

Glycans form a highly variable constituent of our mucosal surfaces and profoundly affect our susceptibility to infection and disease. The diversity and importance of these surface glycans can be seen in individuals who lack a functional copy of the fucosyltransferase gene, FUT2. Representing around one-fifth of the population, these individuals have an altered susceptibility to many bacterial and viral infections and diseases. The mediation of host-pathogen interactions by mucosal glycans, such as those added by FUT2, is poorly understood. We highlight, with specific examples, important mechanisms by which host glycans influence infection dynamics, including by: acting as pathogen receptors (or receptor-decoys), promoting microbial stability, altering the physical characteristics of mucus, and acting as immunological markers. We argue that the effect glycans have on infection dynamics has profound implications for many aspects of healthcare and policy, including clinical management, outbreak control, and vaccination policy.

Evolution of the magic bullet: Single chain antibody fragments for the targeted delivery of immunomodulatory proteins

Immunocytokines are fusion proteins that combine the specific antigen binding capacities of an antibody or derivative thereof and the potent bioactivity of a cytokine partner. These novel biopharmaceuticals have been directed to various targets of oncological as well as non-oncological origin and a handful of promising constructs are currently advancing in the clinical trial pipeline. Several factors such as the choice of a disease specific antigen, the antibody format and the modulatory nature of the payload are crucial, not only for therapeutic efficacy and safety but also for the commercial success of such a product. In this review, we provide an overview of the basic principles and obstacles in immunocytokine design with a specific focus on single chain antibody fragment-based constructs that employ interleukins as the immunoactive component. Impact statement Selective activation of the immune system in a variety of malignancies represents an attractive approach when existing strategies have failed to provide adequate treatment options. Immunocytokines as a novel class of bifunctional protein therapeutics have emerged recently and generated promising results in preclinical and clinical studies. In order to harness their full potential, multiple different aspects have to be taken into consideration. Several key points of these fusion constructs are discussed here and should provide an outline for the development of novel products based on an overview of selected formats.

Mucoadhesive functionality of cell wall structures from fruits and grains: Electrostatic and polymer network interactions mediated by soluble dietary polysaccharides

We demonstrate the enhancement of intestinal mucin (Muc2) binding to plant cell wall structures from fruit (parenchymal apple tissue) and grain (wheat endosperm) mediated by soluble dietary fibers embedded within cellulose networks. Mucin binding occurs through two distinct mechanisms; for pectin polysaccharides characteristic of fruits and vegetables, it is governed by molecular mucoadhesive interactions, while for neutral polysaccharides, arabinoxylan and β-glucan characteristic of cereal grains, the interaction stems from the properties of their polymer network. Based on microrheological and microscopic measurements, we show that neutral dietary fiber polysaccharides do not adhere to intestinal mucin, but are capable of disrupting the mucin network, which facilitates interpenetration of mucin molecules into the polysaccharide mesh. This effect becomes significant in the context of ‘whole foods’, where soluble fibers are incorporated within the gel-like matrix of cellulose-reinforced plant cell wall structures. The result of mucoadhesion assay and analysis of microscopy images points to the critical role of entanglements between mucin and polysaccharides as a lock-in mechanism preventing larger mucin from escaping out of plant cell wall structures. These results provide the first indication that non-pectin soluble dietary fiber may influence mucosal interactions, mucus barrier properties, and transmucosal transport of nutrients.

The effect of interleukin-22 treatment on autoimmune diabetes in the NOD mouse

AIMS/HYPOTHESIS

The aim of this study was to determine whether therapy with the cytokine IL-22 could be used to prevent the development of, or treat, autoimmune diabetes in the NOD mouse.

METHODS

Six-week-old NOD mice were administered bi-weekly either recombinant mouse IL-22 (200 ng/g) or PBS (vehicle control) intraperitoneally until overt diabetes was diagnosed as two consecutive measurements of non-fasting blood glucose ≥ 11 mmol/l. At this time, NOD mice in the control arm were treated with LinBit insulin pellets and randomised to bi-weekly therapeutic injections of either PBS or IL-22 (200 ng/g) and followed until overt diabetes was diagnosed, as defined above.

RESULTS

IL-22 therapy did not delay the onset of diabetes in comparison with the vehicle-treated mice. We did not observe an improvement in islet area, glycaemic control, beta cell residual function, endoplasmic reticulum stress, insulitis or macrophage and neutrophil infiltration as determined by non-fasting blood glucose, C-peptide and histological scoring. Therapeutic administration of IL-22 did not reduce circulating lipopolysaccharide, a marker of impaired gut mucosal integrity.

CONCLUSIONS/INTERPRETATION

Our study suggests that, at this dosing regimen introduced either prior to overt diabetes or at diagnosis of diabetes, recombinant mouse IL-22 therapy cannot prevent autoimmune diabetes, or prolong the honeymoon period in the NOD mouse.

Acute graft-versus-host disease is regulated by an IL-17-sensitive microbiome

Donor T cell-derived IL-17A can mediate late immunopathology in graft-versus-host disease (GVHD), however protective roles remain unclear. Using multiple cytokine and cytokine receptor subunit knockout mice we demonstrate that stem cell transplant (SCT) recipients lacking the ability to generate or signal IL-17 develop intestinal hyper-acute GVHD. This protective effect is restricted to the molecular interaction of IL-17A and/or IL-17F with the IL-17RA/C receptor. The protection from GVHD afforded by IL-17A required secretion from, and signaling in, both hematopoietic and non-hematopoietic host tissue. Given the intestinal-specificity of the disease in these animals, we hypothesized a microbiome contribution. Cohousing of WT with IL-17RA and IL-17RC deficient mice, dramatically enhanced the susceptibility of WT mice to acute GVHD. Furthermore, the gut microbiome of WT mice shifted towards that of the IL-17RA/C mice during cohousing prior to transplant, confirming that IL-17-sensitive gut microbiota controls susceptibility to acute GVHD. Finally, induced IL-17A deletion peri-transplant also enhanced acute GVHD, consistent with an additional protective role for this cytokine independent of effects on dysbiosis. Importantly, this implies that blocking IL-17 in a clinical trial could have adverse effects via dysbiosis, particularly in the early post-transplant setting and raises caution about their potential effects if used long term.

FUT2 genotype influences lung function, exacerbation frequency and airway microbiota in non-CF bronchiectasis

OBJECTIVE

To assess whether FUT2 (secretor) genotype affects disease severity and airway infection in patients with non-cystic fibrosis bronchiectasis.

PARTICIPANTS

Induced sputum samples were obtained from 112 adult patients with high-resolution CT scan-proven bronchiectasis and at least two exacerbations in the previous year, as part of an unrelated randomised control trial.

OUTCOME MEASURES

Presence of null FUT2 polymorphisms were determined by gene sequencing and verified by endobronchial biopsy histochemical staining. Outcome measures were FEV1% predicted, exacerbation frequency, and bacterial, fungal and viral components of the microbiota (measured by culture independent approaches).

RESULTS

Patients were grouped by FUT2 loss-of-function genotype; categorised as non-secretors (n=27, sese), heterozygous secretors (n=54, Sese) or homozygous secretors (n=31, SeSe). FEV1% was significantly lower in SeSe patients compared with sese patients (mean 61.6 (SD 20.0) vs 74.5 (18.0); p=0.023). Exacerbation frequency was significantly higher in SeSe (mean count 5.77) compared with sese (4.07; p=0.004) and Sese (4.63; p=0.026) genotypes. The time until first exacerbation was significantly shorter in SeSe compared with Sese (HR=0.571 (95% CI 0.343 to 0.950); p=0.031), with a similar trend for sese patients (HR=0.577 (0.311 to 1.07); p=0.081). sese had a significantly reduced frequency of Pseudomonas aeruginosa-dominated airway infection (8.7%) compared with Sese (31%; p=0.042) and SeSe (36%; p=0.035). In contrast, fungal, viral and non-dominant bacterial components of the microbiome were not significantly different between FUT2 genotypes.

CONCLUSIONS

FUT2 genotype in patients with non-cystic fibrosis bronchiectasis was significantly associated with disease outcomes, with homozygous secretors exhibiting lower lung function, higher exacerbation number and a higher frequency of P. aeruginosa-dominated infection.

TRIAL REGISTRATION NUMBER

ACTRN12609000578202 (anzctr.org.au); Pre-results.

Bifunctional Succinylated ε-Polylysine-Coated Mesoporous Silica Nanoparticles for pH-Responsive and Intracellular Drug Delivery Targeting the Colon

Conventional oral drug formulations for colonic diseases require the administration of high doses of drug to achieve effective drug concentrations at the target site. However, this exposes patients to serious systemic toxicity in order to achieve efficacy. To overcome this problem, an oral drug delivery system was developed by loading a large amount (ca. 34% w/w) of prednisolone into 3-aminopropyl-functionalized mesoporous silica nanoparticles (MCM-NH₂) and targeting prednisolone release to the colon by coating the nanoparticle with succinylated ε-polylysine (SPL). We demonstrate for the first time the pH-responsive ability of SPL as a "nanogate" to selectively release prednisolone in the pH conditions of the colon (pH 5.5-7.4) but not in the more acidic conditions of the stomach (pH 1.9) or small intestine (pH 5.0). In addition to targeting drug delivery to the colon, we explored whether the nanoparticles could deliver cargo intracellularly to immune cells (RAW 264.7 macrophages) and intestinal epithelial cells (LS 174T and Caco-2 adenocarcinoma cell lines). To trace uptake, MCM-NH₂ were loaded with a cell membrane-impermeable dye, sulforhodamine B. The SPL-coated nanoparticles were able to deliver the dye intracellularly to RAW 264.7 macrophages and the intestinal epithelial cancer cells, which offers a highly promising and novel drug delivery system for diseases of the colon such as inflammatory bowel disease and colorectal cancer.

MUC13 overexpression in renal cell carcinoma plays a central role in tumor progression and drug resistance

Metastatic renal cell carcinoma is a largely incurable disease, and existing treatments targeting angiogenesis and tyrosine kinase receptors are only partially effective. Here we reveal that MUC13, a cell surface mucin glycoprotein, is aberrantly expressed by most renal cell carcinomas, with increasing expression positively correlating with tumor grade. Importantly, we demonstrated that high MUC13 expression was a statistically significant independent predictor of poor survival in two independent cohorts, particularly in stage 1 cancers. In cultured renal cell carcinoma cells MUC13 promoted proliferation and induced the cell cycle regulator, cyclin D1, and inhibited apoptosis by inducing the anti-apoptotic proteins, BCL-xL and survivin. Silencing of MUC13 expression inhibited migration and invasion, and sensitized renal cancer cells to killing by the multi-kinase inhibitors used clinically, sorafenib and sunitinib, and reversed acquired resistance to these drugs. Furthermore, we demonstrated that MUC13 promotion of renal cancer cell growth and survival is mediated by activation of nuclear factor κB, a transcription factor known to regulate the expression of genes that play key roles in the development and progression of cancer. These results show that MUC13 has potential as a prognostic marker for aggressive early stage renal cell cancer and is a plausible target to sensitize these tumors to therapy.

Immune-driven alterations in mucin sulphation is an important mediator of Trichuris muris helminth expulsion

Mucins are heavily glycosylated proteins that give mucus its gel-like properties. Moreover, the glycans decorating the mucin protein core can alter the protective properties of the mucus barrier. To investigate whether these alterations could be parasite-induced we utilized the Trichuris muris (T. muris) infection model, using different infection doses and strains of mice that are resistant (high dose infection in BALB/c and C57BL6 mice) or susceptible (high dose infection in AKR and low dose infection in BALB/c mice) to chronic infection by T. muris. During chronicity, within the immediate vicinity of the T. muris helminth the goblet cell thecae contained mainly sialylated mucins. In contrast, the goblet cells within the epithelial crypts in the resistant models contained mainly sulphated mucins. Maintained mucin sulphation was promoted by T_H2-immune responses, in particular IL-13, and contributed to the protective properties of the mucus layer, making it less vulnerable to degradation by T. muris excretory secretory products. Mucin sulphation was markedly reduced in the caecal goblet cells in the sulphate anion transporter-1 (Sat-1) deficient mice. We found that Sat-1 deficient mice were susceptible to chronic infection despite a strong T_H2-immune response. Lower sulphation levels lead to decreased efficiency of establishment of T. muris infection, independent of egg hatching. This study highlights the complex process by which immune-regulated alterations in mucin glycosylation occur following T. muris infection, which contributes to clearance of parasitic infection.

Approximately 2 billion people are infected with worms every year, causing physical, nutritional and cognitive impairment particularly in children. Mucins are large sugar-coated (glycosylated) proteins that form the intestinal mucus layer. This mucus layer protects our ‘insides’ from external insults and plays an important role during worm infection. We discovered that there is a difference in the glycosylation of mucins in people infected with worms compared to uninfected individuals. Therefore, using different mouse models we investigated the role of glycosylation, and in particular sulphation of mucins in infection. We found that mucin glycosylation is controlled by the immune response and increased sulphation correlated with the expulsion of the worm from the host. Highly sulphated mucins were protected from degradation by the worm. Moreover, mice lacking a sulphate transporter had significantly lower sulphation levels on mucins, which resulted in a reduction in the establishment of the worms and chronic infection.

MUC13 protects colorectal cancer cells from death by activating the NF-κB pathway and is a potential therapeutic target

MUC13 is a transmembrane mucin glycoprotein that is over produced by many cancers, although its functions are not fully understood. Nuclear factor-κB (NF-κB) is a key transcription factor promoting cancer cell survival, but therapeutically targeting this pathway has proved difficult because NF-κB has pleiotropic functions. Here, we report that MUC13 prevents colorectal cancer cell death by promoting two distinct pathways of NF-kB activation, consequently upregulating BCL-X_L. MUC13 promoted tumor necrosis factor (TNF)-induced NF-κB activation by interacting with TNFR1 and the E3 ligase, cIAP1, to increase ubiquitination of RIPK1. MUC13 also promoted genotoxin-induced NF-κB activation by increasing phosphorylation of ATM and SUMOylation of NF-κB essential modulator. Moreover, elevated expression of cytoplasmic MUC13 and NF-κB correlated with colorectal cancer progression and metastases. Our demonstration that MUC13 enhances NF-κB signaling in response to both TNF and DNA-damaging agents provides a new molecular target for specific inhibition of NF-κB activation. As proof of principle, silencing MUC13 sensitized colorectal cancer cells to killing by cytotoxic drugs and inflammatory signals and abolished chemotherapy-induced enrichment of CD133⁺ CD44⁺ cancer stem cells, slowed xenograft growth in mice, and synergized with 5-fluourouracil to induce tumor regression. Therefore, these data indicate that combining chemotherapy and MUC13 antagonism could improve the treatment of metastatic cancers.

The MUC1 mucin protects against Helicobacter pylori pathogenesis in mice by regulation of the NLRP3 inflammasome

OBJECTIVES

The mucin MUC1, best known for providing an epithelial barrier, is an important protective host factor in both humans and mice during Helicobacter pylori pathogenesis. This study aimed to identify the long-term consequences of MUC1 deficiency on H. pylori pathogenesis and the mechanism by which MUC1 protects against H. pylori gastritis.

DESIGN

Wildtype and Muc1(-/-) mice were infected for up to 9 months, and the gastric pathology, immunological response and epigenetic changes assessed. The effects of MUC1 on the inflammasome, a potent inflammatory pathway, were examined in macrophages and H. pylori-infected mice deficient in both MUC1 and inflammasome components.

RESULTS

Muc1(-/-) mice began to die 6 months after challenge, indicating Muc1 deficiency made H. pylori a lethal infection. Surprisingly, chimaeric mouse infections revealed MUC1 expression by haematopoietic-derived immune cells limits H. pylori-induced gastritis. Gastritis in infected Muc1(-/-) mice was associated with elevated interleukin (IL)-1β and epigenetic changes in their gastric mucosa similar to those in transgenic mice overexpressing gastric IL-1β, implicating MUC1 regulation of an inflammasome. In support of this, infected Muc1(-/-)Casp1(-/-) mice did not develop severe gastritis. Further, MUC1 regulated Nlrp3 expression via an nuclear factor (NF)-κB-dependent pathway and reduced NF-κB pathway activation via inhibition of IRAK4 phosphorylation. The importance of this regulation was proven using Muc1(-/-)Nlrp3(-/-) mice, which did not develop severe gastritis.

CONCLUSIONS

MUC1 is an important, previously unidentified negative regulator of the NLRP3 inflammasome. H. pylori activation of the NLRP3 inflammasome is normally tightly regulated by MUC1, and loss of this critical regulation results in the development of severe pathology.

High Fat Diets Induce Colonic Epithelial Cell Stress and Inflammation that is Reversed by IL-22

Prolonged high fat diets (HFD) induce low-grade chronic intestinal inflammation in mice, and diets high in saturated fat are a risk factor for the development of human inflammatory bowel diseases. We hypothesized that HFD-induced endoplasmic reticulum (ER)/oxidative stress occur in intestinal secretory goblet cells, triggering inflammatory signaling and reducing synthesis/secretion of proteins that form the protective mucus barrier. In cultured intestinal cells non-esterified long-chain saturated fatty acids directly increased oxidative/ER stress leading to protein misfolding. A prolonged HFD elevated the intestinal inflammatory cytokine signature, alongside compromised mucosal barrier integrity with a decrease in goblet cell differentiation and Muc2, a loss in the tight junction protein, claudin-1 and increased serum endotoxin levels. In Winnie mice, that develop spontaneous colitis, HFD-feeding increased ER stress, further compromised the mucosal barrier and increased the severity of colitis. In obese mice IL-22 reduced ER/oxidative stress and improved the integrity of the mucosal barrier, and reversed microbial changes associated with obesity with an increase in Akkermansia muciniphila. Consistent with epidemiological studies, our experiments suggest that HFDs are likely to impair intestinal barrier function, particularly in early life, which partially involves direct effects of free-fatty acids on intestinal cells, and this can be reversed by IL-22 therapy.

Oxidative and endoplasmic reticulum stress in β-cell dysfunction in diabetes

The inability of pancreatic β-cells to make sufficient insulin to control blood sugar is a central feature of the aetiology of most forms of diabetes. In this review we focus on the deleterious effects of oxidative stress and endoplasmic reticulum (ER) stress on β-cell insulin biosynthesis and secretion and on inflammatory signalling and apoptosis with a particular emphasis on type 2 diabetes (T2D). We argue that oxidative stress and ER stress are closely entwined phenomena fundamentally involved in β-cell dysfunction by direct effects on insulin biosynthesis and due to consequences of the ER stress-induced unfolded protein response. We summarise evidence that, although these phenomenon can be driven by intrinsic β-cell defects in rare forms of diabetes, in T2D β-cell stress is driven by a range of local environmental factors including increased drivers of insulin biosynthesis, glucolipotoxicity and inflammatory cytokines. We describe our recent findings that a range of inflammatory cytokines contribute to β-cell stress in diabetes and our discovery that interleukin 22 protects β-cells from oxidative stress regardless of the environmental triggers and can correct much of diabetes pathophysiology in animal models. Finally we summarise evidence that β-cell dysfunction is reversible in T2D and discuss therapeutic opportunities for relieving oxidative and ER stress and restoring glycaemic control.

Epithelial Sel1L is required for the maintenance of intestinal homeostasis

Inflammatory bowel disease (IBD) is an incurable chronic idiopathic disease that drastically decreases quality of life. Endoplasmic reticulum (ER)-associated degradation (ERAD) is responsible for the clearance of misfolded proteins; however, its role in disease pathogenesis remains largely unexplored. Here we show that the expression of SEL1L and HRD1, the most conserved branch of mammalian ERAD, is significantly reduced in ileal Crohn's disease (CD). Consistent with this observation, laboratory mice with enterocyte-specific Sel1L deficiency (Sel1L(ΔIEC)) develop spontaneous enteritis and have increased susceptibility to Toxoplasma gondii-induced ileitis. This is associated with profound defects in Paneth cells and a disproportionate increase of Ruminococcus gnavus, a mucolytic bacterium with known association with CD. Surprisingly, whereas both ER stress sensor IRE1α and effector CHOP are activated in the small intestine of Sel1L(ΔIEC) mice, they are not solely responsible for ERAD deficiency-associated lesions seen in the small intestine. Thus our study points to a constitutive role of Sel1L-Hrd1 ERAD in epithelial cell biology and the pathogenesis of intestinal inflammation in CD.

Adult non-cystic fibrosis bronchiectasis is characterised by airway luminal Th17 pathway activation

BACKGROUND

Non-cystic fibrosis (CF) bronchiectasis is characterised by chronic airway infection and neutrophilic inflammation, which we hypothesised would be associated with Th17 pathway activation.

METHODS

Th17 pathway cytokines were quantified in bronchoalveolar lavage fluid (BALF), and gene expression of IL-17A, IL-1β, IL-8 and IL-23 determined from endobronchial biopsies (EBx) in 41 stable bronchiectasis subjects and 20 healthy controls. Relationships between IL-17A levels and infection status, important clinical measures and subsequent Pseudomonas aeruginosa infection were determined.

RESULTS

BALF levels of all Th17 cytokines (median (IQR) pg/mL) were significantly higher in bronchiectasis than control subjects, including IL-17A (1.73 (1.19, 3.23) vs. 0.27 (0.24, 0.35), 95% CI 1.05 to 2.21, p<0.0001) and IL-23 (9.48 (4.79, 15.75) vs. 0.70 (0.43, 1.79), 95% CI 4.68 to 11.21, p<0.0001). However, BALF IL-17A levels were not associated with clinical measures or airway microbiology, nor predictive of subsequent P. aeruginosa infection. Furthermore, gene expression of IL-17A in bronchiectasis EBx did not differ from control. In contrast, gene expression (relative to medians of controls) in bronchiectasis EBx was significantly higher than control for IL1β (4.12 (1.24, 8.05) vs 1 (0.13, 2.95), 95% CI 0.05 to 4.07, p = 0.04) and IL-8 (3.75 (1.64, 11.27) vs 1 (0.54, 3.89), 95% CI 0.32 to 4.87, p = 0.02) and BALF IL-8 and IL-1α levels showed significant relationships with clinical measures and airway microbiology. P. aeruginosa infection was associated with increased levels of IL-8 while Haemophilus influenzae was associated with increased IL-1α.

CONCLUSIONS AND CLINICAL RELEVANCE

Established adult non-CF bronchiectasis is characterised by luminal Th17 pathway activation, however this pathway may be relatively less important than activation of non-antigen-specific innate neutrophilic immunity.

Glycemic control in diabetes is restored by therapeutic manipulation of cytokines that regulate beta cell stress

In type 2 diabetes, hyperglycemia is present when an increased demand for insulin, typically due to insulin resistance, is not met as a result of progressive pancreatic beta cell dysfunction. This defect in beta cell activity is typically characterized by impaired insulin biosynthesis and secretion, usually accompanied by oxidative and endoplasmic reticulum (ER) stress. We demonstrate that multiple inflammatory cytokines elevated in diabetic pancreatic islets induce beta cell oxidative and ER stress, with interleukin-23 (IL-23), IL-24 and IL-33 being the most potent. Conversely, we show that islet-endogenous and exogenous IL-22, by regulating oxidative stress pathways, suppresses oxidative and ER stress caused by cytokines or glucolipotoxicity in mouse and human beta cells. In obese mice, antibody neutralization of IL-23 or IL-24 partially reduced beta cell ER stress and improved glucose tolerance, whereas IL-22 administration modulated oxidative stress regulatory genes in islets, suppressed ER stress and inflammation, promoted secretion of high-quality efficacious insulin and fully restored glucose homeostasis followed by restitution of insulin sensitivity. Thus, therapeutic manipulation of immune regulators of beta cell stress reverses the hyperglycemia central to diabetes pathology.

ZAP-70 genotype disrupts the relationship between microbiota and host, leading to spondyloarthritis and ileitis in SKG mice

OBJECTIVE

The spondyloarthritides share genetic susceptibility, interleukin-23 (IL-23) dependence, and the involvement of microbiota. The aim of the current study was to elucidate how host genetics influence gut microbiota and the relationship between microbiota and organ inflammation in spondyloarthritides.

METHODS

BALB/c ZAP-70(W163C) -mutant (SKG) mice, Toll-like receptor 4 (TLR-4)-deficient SKG mice, and wild-type BALB/c mice were housed under specific pathogen-free conditions. SKG and wild-type BALB/c mice were maintained under germ-free conditions, and some of these mice were recolonized with altered Schaedler flora. All of the mice were injected intraperitoneally with microbial β-1,3-glucan (curdlan). Arthritis, spondylitis, and ileitis were assessed histologically. Microbiome composition was analyzed in serial fecal samples obtained from mice that were co-housed beginning at the time of weaning, using 454 pyrosequencing. Infiltrating cells and cytokines in the peritoneal cavity were measured by flow cytometry and enzyme-linked immunosorbent assay. Cytokine, endoplasmic reticulum (ER) stress marker, and tight junction protein transcription was measured by quantitative real-time polymerase chain reaction.

RESULTS

Microbiota content and response to curdlan varied according to whether T cell receptor signal strength was normal or was impaired due to the ZAP-70(W163C) mutation. Curdlan triggered acute inflammation regardless of the presence of the SKG allele or microbiota. However, no or limited microbiota content attenuated the severity of arthritis. In contrast, ileal IL-23 expression, ER stress, lymph node IL-17A production, goblet cell loss, and ileitis development were microbiota-dependent. Ileitis but not arthritis was suppressed by microbiota transfer upon co-housing SKG mice with wild-type BALB/c mice, as well as by TLR-4 deficiency.

CONCLUSION

The interaction between immunogenetic background and host microbiota leads to an IL-23-dependent loss of mucosal function, triggering ileitis in response to curdlan.

Interleukin-23 mediates the intestinal response to microbial β-1,3-glucan and the development of spondyloarthritis pathology in SKG mice

OBJECTIVE

Spondyloarthritides (SpA) occur in 1% of the population and include ankylosing spondylitis (AS) and arthropathy of inflammatory bowel disease (IBD), with characteristic spondylitis, arthritis, enthesitis, and IBD. Genetic studies implicate interleukin-23 (IL-23) receptor signaling in the development of SpA and IBD, and IL-23 overexpression in mice is sufficient for enthesitis, driven by entheseal-resident T cells. However, in genetically prone individuals, it is not clear where IL-23 is produced and how it drives the SpA syndrome, including IBD or subclinical gut inflammation of AS. Moreover, it is unclear why specific tissue involvement varies between patients with SpA. We undertook this study to determine the location of IL-23 production and its role in SpA pathogenesis in BALB/c ZAP-70(W163C)-mutant (SKG) mice injected intraperitoneally with β-1,3-glucan (curdlan).

METHODS

Eight weeks after curdlan injection in wild-type or IL-17A(-/-) SKG or BALB/c mice, pathology was scored in tissue sections. Mice were treated with anti-IL-23 or anti-IL-22. Cytokine production and endoplasmic reticulum (ER) stress were determined in affected organs.

RESULTS

In curdlan-treated SKG mice, arthritis, enthesitis, and ileitis were IL-23 dependent. Enthesitis was specifically dependent on IL-17A and IL-22. IL-23 was induced in the ileum, where it amplified ER stress, goblet cell dysfunction, and proinflammatory cytokine production. IL-17A was pathogenic, while IL-22 was protective against ileitis. IL-22+CD3- innate-like cells were increased in lamina propria mononuclear cells of ileitis-resistant BALB/c mice, which developed ileitis after curdlan injection and anti-IL-22.

CONCLUSION

In response to systemic β-1,3-glucan, intestinal IL-23 provokes local mucosal dysregulation and cytokines driving the SpA syndrome, including IL-17/IL-22-dependent enthesitis. Innate IL-22 production promotes ileal tolerance.

Selenoprotein S is a marker but not a regulator of endoplasmic reticulum stress in intestinal epithelial cells

Selenoproteins are candidate mediators of selenium-dependent protection against tumorigenesis and inflammation in the gut. Expression and roles of only a limited number of intestinal selenoproteins have been described so far. Selenoprotein S (SelS) has been linked to various inflammatory diseases and is suggested to be involved in endoplasmic reticulum (ER) homeostasis regulation and antioxidative protection in a cell-type-dependent manner, but its protein expression, regulation, and function in the gut are not known. We here analyzed the expression and localization of SelS in the healthy and inflamed gut and studied its regulation and function in intestinal epithelial cell lines. SelS was expressed in the intestinal epithelium of the small and large intestine and colocalized with markers of Paneth cells and macrophages. It was upregulated in inflamed ileal tissue from Crohn's disease patients and in two models of experimental colitis in mice. We detected SelS in colorectal cell lines, where it colocalized with the ER marker calnexin. SelS protein expression was unaffected by enterocytic differentiation but increased in response to selenium supplementation and after treatment with the ER stress inducer tunicamycin. On the other hand, depletion of SelS in LS174T, HT29, and Caco-2 cells by RNA interference did not cause or modulate ER stress and had no effect on hydrogen peroxide-induced cell death. In summary, we introduce SelS as a novel marker of Paneth cells and intestinal ER stress. Although it is upregulated in Crohn's disease, its role in disease etiology remains to be established.

Expression of MUC2, MUC5AC, MUC5B, and MUC6 mucins in colorectal cancers and their association with the CpG island methylator phenotype

Mucinous differentiation is associated with both CpG island methylator phenotype and microsatellite instability in colorectal cancer. The mucinous phenotype derives from abundant expression of the colonic goblet cell mucin, MUC2, and de novo expression of gastric foveolar mucin, MUC5AC. We, therefore, investigated the protein expression levels of MUC2 and MUC5AC, as well as MUC5B and MUC6, in molecular subtypes of colorectal cancer. Seven-hundred and twenty-two incident colorectal carcinomas occurring in 702 participants of the Melbourne Collaborative Cohort Study were characterized for methylator status, MLH1 methylation, somatic BRAF and KRAS mutations, microsatellite-instability status, MLH1, MSH2, MSH6, and PMS2 mismatch repair, and p53 protein expression, and their histopathology was reviewed. Protein expression levels of MUC2, MUC5AC, MUC5B, MUC6, and the putative mucin regulator CDX2 were compared with molecular and clinicopathological features of colorectal cancers using odds ratios and corresponding 95% confidence intervals. MUC2 overexpression (>25% positive tumor cells) was observed in 33% colorectal cancers, MUC5B expression in 53%, and de novo MUC5AC and MUC6 expression in 50% and 39%, respectively. Co-expression of two or more of the mucins was commonly observed. Expression of MUC2, MUC5AC and MUC6 was strongly associated with features associated with tumorigenesis via the serrated neoplasia pathway, including methylator positivity, somatic BRAF p.V600E mutation, and mismatch repair deficiency, as well as proximal location, poor differentiation, lymphocytic response, and increased T stage (all P<0.001). Overexpression was observed in tumors with and without mucinous differentiation. There were inverse associations between expression of all four mucins and p53 overexpression. CDX2 expression was inversely associated with MUC2, MUC5AC and MUC6 expression. Our results suggest that, in methylator-positive tumors, mucin genes on chromosome 11p15.5 region undergo increased expression via mechanisms other than direct regulation by CDX2.

Gastrointestinal cell lines form polarized epithelia with an adherent mucus layer when cultured in semi-wet interfaces with mechanical stimulation

Mucin glycoproteins are secreted in large quantities by mucosal epithelia and cell surface mucins are a prominent feature of the glycocalyx of all mucosal epithelia. Currently, studies investigating the gastrointestinal mucosal barrier use either animal experiments or non-in vivo like cell cultures. Many pathogens cause different pathology in mice compared to humans and the in vitro cell cultures used are suboptimal because they are very different from an in vivo mucosal surface, are often not polarized, lack important components of the glycocalyx, and often lack the mucus layer. Although gastrointestinal cell lines exist that produce mucins or polarize, human cell line models that reproducibly create the combination of a polarized epithelial cell layer, functional tight junctions and an adherent mucus layer have been missing until now. We trialed a range of treatments to induce polarization, 3D-organization, tight junctions, mucin production, mucus secretion, and formation of an adherent mucus layer that can be carried out using standard equipment. These treatments were tested on cell lines of intestinal (Caco-2, LS513, HT29, T84, LS174T, HT29 MTX-P8 and HT29 MTX-E12) and gastric (MKN7, MKN45, AGS, NCI-N87 and its hTERT Clone5 and Clone6) origins using Ussing chamber methodology and (immuno)histology. Semi-wet interface culture in combination with mechanical stimulation and DAPT caused HT29 MTX-P8, HT29 MTX-E12 and LS513 cells to polarize, form functional tight junctions, a three-dimensional architecture resembling colonic crypts, and produce an adherent mucus layer. Caco-2 and T84 cells also polarized, formed functional tight junctions and produced a thin adherent mucus layer after this treatment, but with less consistency. In conclusion, culture methods affect cell lines differently, and testing a matrix of methods vs. cell lines may be important to develop better in vitro models. The methods developed herein create in vitro mucosal surfaces suitable for studies of host-pathogen interactions at the mucosal surface.

Lynch syndrome-associated breast cancers do not overexpress chromosome 11-encoded mucins

Mismatch repair-deficient breast cancers may be identified in Lynch syndrome mutation carriers, and have clinicopathological features in common with mismatch repair-deficient colorectal and endometrial cancers such as tumour-infiltrating lymphocytes and poor differentiation. Mismatch repair-deficient colorectal cancers frequently show mucinous differentiation associated with upregulation of chromosome 11 mucins. The aim of this study was to compare the protein expression of these mucins in mismatch repair-deficient and -proficient breast cancers. Cases of breast cancer (n=100) were identified from families where (1) both breast and colon cancer co-occurred and (2) families met either modified Amsterdam criteria or had at least one early-onset (<50 years) colorectal cancer. Tumour sections were stained for the epithelial mucins, MUC2, MUC5AC, MUC5B and MUC6, and the homeobox protein CDX2, a regulator of MUC2 expression. In all, 16 mismatch repair-deficient Lynch syndrome breast cancers and 84 non-Lynch breast cancers were assessed for altered mucin expression. No significant difference in the expression of MUC2, MUC5AC or MUC6 was observed between the mismatch repair-deficient and mismatch repair-proficient breast cancers; however, there was a trend for mismatch repair-deficient tumours to express high levels of MUC5B less frequently (P=0.07, OR=0.2 (0.0-1.0)). Co-expression of two or more gel-forming mucins was common. Ectopic expression of CDX2 was associated with expression of MUC2 (P=0.035, OR=8.7 (1.3-58.4)). Mismatch repair-deficient breast cancers do not show differential expression of the mucins genes on chromosome 11 when compared with mismatch repair-proficient breast cancers, in contrast with mismatch repair-deficient colorectal and endometrial cancers, which frequently have increased mucin protein expression when compared with their mismatch repair-proficient counterparts. In addition, ectopic CDX2 expression is positively associated with de novo MUC2 expression.

Glucocorticoids alleviate intestinal ER stress by enhancing protein folding and degradation of misfolded proteins

Dexamethasone suppresses ER stress in inflammatory bowel disease by promoting correct protein folding and ER-associated degradation.

Endoplasmic reticulum (ER) stress in intestinal secretory cells has been linked with colitis in mice and inflammatory bowel disease (IBD). Endogenous intestinal glucocorticoids are important for homeostasis and glucocorticoid drugs are efficacious in IBD. In Winnie mice with intestinal ER stress caused by misfolding of the Muc2 mucin, the glucocorticoid dexamethasone (DEX) suppressed ER stress and activation of the unfolded protein response (UPR), substantially restoring goblet cell Muc2 production. In mice lacking inflammation, a glucocorticoid receptor antagonist increased ER stress, and DEX suppressed ER stress induced by the N-glycosylation inhibitor, tunicamycin (Tm). In cultured human intestinal secretory cells, in a glucocorticoid receptor-dependent manner, DEX suppressed ER stress and UPR activation induced by blocking N-glycosylation, reducing ER Ca²⁺ or depleting glucose. DEX up-regulated genes encoding chaperones and elements of ER-associated degradation (ERAD), including EDEM1. Silencing EDEM1 partially inhibited DEX’s suppression of misfolding-induced ER stress, showing that DEX enhances ERAD. DEX inhibited Tm-induced MUC2 precursor accumulation, promoted production of mature mucin, and restored ER exit and secretion of Winnie mutant recombinant Muc2 domains, consistent with enhanced protein folding. In IBD, glucocorticoids are likely to ameliorate ER stress by promoting correct folding of secreted proteins and enhancing removal of misfolded proteins from the ER.

A novel mouse model of veno-occlusive disease provides strategies to prevent thioguanine-induced hepatic toxicity

OBJECTIVE

The anti-leukemic drugs, azathioprine and 6-mercaptopurine (6MP), are important in the treatment of inflammatory bowel disease but an alternative faster-acting, less-allergenic thiopurine, 6-thioguanine (6TG), can cause hepatic veno-occlusive disease/sinusoidal obstructive syndrome (SOS). Understanding of SOS has been hindered by inability to ethically perform serial liver biopsies on patients and the lack of an animal model.

DESIGN

Normal and C57Bl/6 mice with specific genes altered to elucidate mechanisms responsible for 6TG-SOS, were gavaged daily for upto 28d with 6TG, 6MP or methylated metabolites. Animal survival was monitored and at sacrifice a histological score of SOS, haematology and liver biochemistry were measured.

RESULTS

Only 6TG caused SOS, which was dose related. 6TG and to a lesser extent 6MP but not methylated metabolites were associated with dose-dependent haematopoietic toxicity. SOS was not detected with non-lethal doses of 6TG. SOS did not occur in hypoxanthine-phosphoribosyl transferase-deficient C57Bl/6 mice, demonstrating that 6TG-SOS requires thioguanine nucleotides. Hepatic inflammation was characteristic of SOS, and C57Bl/6 mice deficient in P- and E-selectins on the surface of vascular endothelial cells showed markedly reduced SOS, demonstrating a major role for leukocytes recruited from blood. Split dosing of 6TG markedly attenuated SOS but still effected immunosuppression and prevented spontaneous colitis in Winnie mice, which have a single nucleotide polymorphism mutation in Muc2.

CONCLUSION

This novel model provides clinically relevant insights into how 6TG induces SOS, and how this dangerous adverse drug reaction may be avoided by either inhibition of endothelial activation or simple changes to dosing regimens of 6TG, while still being effective treatment for colitis.

Extracellular cathepsin K exerts antimicrobial activity and is protective against chronic intestinal inflammation in mice

OBJECTIVE

Cathepsin K is a lysosomal cysteine protease that has pleiotropic roles in bone resorption, arthritis, atherosclerosis, blood pressure regulation, obesity and cancer. Recently, it was demonstrated that cathepsin K-deficient (Ctsk(-/-) ) mice are less susceptible to experimental autoimmune arthritis and encephalomyelitis, which implies a functional role for cathepsin K in chronic inflammatory responses. Here, the authors address the relevance of cathepsin K in the intestinal immune response during chronic intestinal inflammation.

DESIGN

Chronic colitis was induced by administration of 2% dextran sodium sulphate (DSS) in distilled water. Mice were assessed for disease severity, histopathology and endoscopic appearance. Furthermore, DSS-exposed Ctsk(-/-) mice were treated by rectal administration of recombinant cathepsin K. Intestinal microflora was assessed by real-time PCR and 16srDNA molecular fingerprinting of ileal and colonic mucosal and faecal samples.

RESULTS

Using Ctsk(-/-) mice, the authors demonstrate a protective role of cathepsin K against chronic DSS colitis. Dissecting the underlying mechanisms the authors found cathepsin K to be present in intestinal goblet cells and the mucin layer. Furthermore, a direct cathepsin K-mediated bactericidal activity against intestinal bacteria was demonstrated, which potentially explains the alteration of intestinal microbiota observed in Ctsk(-/-) mice. Rectal administration of recombinant cathepsin K in DSS-treated Ctsk(-/-) mice ameliorates the severity of intestinal inflammation.

CONCLUSION

These data identify extracellular cathepsin K as an intestinal antibacterial factor with anti-inflammatory potential and suggest that topical administration of cathepsin K might provide a therapeutic option for patients with inflammatory bowel disease.

Effect of long-term, low-dose erythromycin on pulmonary exacerbations among patients with non-cystic fibrosis bronchiectasis: the BLESS randomized controlled trial

IMPORTANCE

Macrolide antibiotics such as erythromycin may improve clinical outcomes in non-cystic fibrosis (CF) bronchiectasis, although associated risks of macrolide resistance are poorly defined.

OBJECTIVE

To evaluate the clinical efficacy and antimicrobial resistance cost of low-dose erythromycin given for 12 months to patients with non-CF bronchiectasis with a history of frequent pulmonary exacerbations.

DESIGN, SETTING, AND PARTICIPANTS

Twelve-month, randomized (1:1), double-blind, placebo-controlled trial of erythromycin in currently nonsmoking, adult patients with non-CF bronchiectasis with a history of 2 or more infective exacerbations in the preceding year. This Australian study was undertaken between October 2008 and December 2011 in a university teaching hospital, with participants also recruited via respiratory physicians at other centers and from public radio advertisements.

INTERVENTIONS

Twice-daily erythromycin ethylsuccinate (400 mg) or matching placebo.

MAIN OUTCOME MEASURES

The primary outcome was the annualized mean rate of protocol-defined pulmonary exacerbations (PDPEs) per patient. Secondary outcomes included macrolide resistance in commensal oropharyngeal streptococci and lung function.

RESULTS

Six-hundred seventy-nine patients were screened, 117 were randomized (58 placebo, 59 erythromycin), and 107 (91.5%) completed the study. Erythromycin significantly reduced PDPEs both overall (mean, 1.29 [95% CI, 0.93-1.65] vs 1.97 [95% CI, 1.45-2.48] per patient per year; incidence rate ratio [IRR], 0.57 [95% CI, 0.42-0.77]; P = .003), and in the prespecified subgroup with baseline Pseudomonas aeruginosa airway infection (mean difference, 1.32 [95% CI, 0.19-2.46]; P = .02). Erythromycin reduced 24-hour sputum production (median difference, 4.3 g [interquartile range [IQR], 1 to 7.8], P = .01) and attenuated lung function decline (mean absolute difference for change in postbronchodilator forced expiratory volume in the first second of expiration, 2.2 percent predicted [95% CI, 0.1% to 4.3%]; P = .04) compared with placebo. Erythromycin increased the proportion of macrolide-resistant oropharyngeal streptococci (median change, 27.7% [IQR, 0.04% to 41.1%] vs 0.04% [IQR, -1.6% to 1.5%]; difference, 25.5% [IQR,15.0% to 33.7%]; P < .001).

CONCLUSION AND RELEVANCE

Among patients with non-CF bronchiectasis, the 12-month use of erythromycin compared with placebo resulted in a modest decrease in the rate of pulmonary exacerbations and an increased rate of macrolide resistance.

TRIAL REGISTRATION

anzctr.org.au Identifier: ACTRN12609000578202.

Paclitaxel resistance and multicellular spheroid formation are induced by kallikrein-related peptidase 4 in serous ovarian cancer cells in an ascites mimicking microenvironment

High tumor kallikrein-related-peptidase 4 (KLK4) levels are associated with a poor outcome for women with serous epithelial ovarian cancer (EOC), for which peritoneal dissemination and chemoresistance are key events. To determine the role of KLK4 in these events, we examined KLK4-transfected SKOV-3 and endogenous KLK4 expressing OVCA432 cells in 3-dimensional (3D) suspension culture to mimic the ascites microenvironment. KLK4-SKOV-3 cells formed multicellular aggregates (MCAs) as seen in ascites, as did SKOV-3 cells treated with active KLK4. MCA formation was reduced by treatment with a KLK4 blocking antibody or the selective active site KLK4 sunflower trypsin inhibitor (SFTI-FCQR). KLK4-MCAs formed larger cancer cell foci in mesothelial cell monolayers than those formed by vector and native SKOV-3 cells, suggesting KLK4-MCAs are highly invasive in the peritoneal microenvironment. A high level of KLK4 is expressed by ascitic EOC cells compared to matched primary tumor cells, further supporting its role in the ascitic microenvironment. Interestingly, KLK4 transfected SKOV-3 cells expressed high levels of the KLK4 substrate, urokinase plasminogen activator (uPA), particularly in 3D-suspension, and high levels of both KLK4 and uPA were observed in patient cells taken from ascites. Importantly, the KLK4-MCAs were paclitaxel resistant which was reversed by SFTI-FCQR and to a lesser degree by the general serine protease inhibitor, Aprotinin, suggesting that in addition to uPA, other as yet unidentified substrates of KLK4 must be involved. Nonetheless, these data suggest that KLK4 inhibition, in conjunction with paclitaxel, may improve the outcome for women with serous epithelial ovarian cancer and high KLK4 levels in their tumors.

IL-10 promotes production of intestinal mucus by suppressing protein misfolding and endoplasmic reticulum stress in goblet cells

BACKGROUND & AIMS

Protein misfolding and endoplasmic reticulum (ER) stress have been observed in intestinal secretory cells from patients with inflammatory bowel diseases and induce intestinal inflammation in mice. However, it is not clear how immune factors affect ER stress and therefore disease symptoms.

METHODS

We analyzed the effects of interleukin (IL)-10 on ER stress in intestinal tissues in wild-type C57BL/6, Winnie, IL-10(-/-), and Winnie × IL-10(+/-) mice. In Winnie mice, misfolding of the intestinal mucin Muc2 initiates ER stress and inflammation. We also analyzed the effects of different inhibitors of IL-10 signaling and the N-glycosylation inhibitor tunicamycin in cultured human LS174T goblet cells.

RESULTS

Administration of neutralizing antibodies against IL-10 or its receptor (IL-10R1) to Winnie mice rapidly exacerbated ER stress and intestinal inflammation compared with mice given vehicle (controls). Antibodies against IL-10 also increased accumulation of misfolded Muc2 in the ER of goblet cells of Winnie mice and increased T-cell production of inflammatory cytokines. Winnie × IL-10(+/-) mice and IL-10(-/-) mice with a single Winnie allele each developed more severe inflammation than Winnie mice or IL-10(-/-) mice. Administration of tunicamycin to wild-type mice caused intestinal ER stress, which increased when IL-10R1 was blocked. In LS174T cells, induction of ER stress with tunicamycin and misfolding of MUC2 were reduced by administration of IL-10; this reduction required STAT1 and STAT3. In LS174T cells incubated with tunicamycin, IL-10 up-regulated genes involved in MUC2 folding and in ER-associated degradation and maintained correct folding of MUC2, its transport from the ER, and its O-glycosylation and secretion.

CONCLUSIONS

IL-10 prevents protein misfolding and ER stress by maintaining mucin production in goblet cells and helps the intestine preserve the mucus barrier.

A novel NOD1- and CagA-independent pathway of interleukin-8 induction mediated by the Helicobacter pylori type IV secretion system

The type IV secretion system (T4SS) of Helicobacter pylori triggers massive inflammatory responses during gastric infection by mechanisms that are poorly understood. Here we provide evidence for a novel pathway by which the T4SS structural component, CagL, induces secretion of interleukin-8 (IL-8) independently of CagA translocation and peptidoglycan-sensing nucleotide-binding oligomerization domain 1 (NOD1) signalling. Recombinant CagL was sufficient to trigger IL-8 secretion, requiring activation of α5 β1 integrin and the arginine-glycine-aspartate (RGD) motif in CagL. Mutation of the encoded RGD motif to arginine-glycine-alanine (RGA) in the cagL gene of H. pylori abrogated its ability to induce IL-8. Comparison of IL-8 induction between H. pylori ΔvirD4 strains bearing wild-type or mutant cagL indicates that CagL-dependent IL-8 induction can occur independently of CagA translocation. In line with this notion, exogenous CagL complemented H. pylori ΔcagL mutant in activating NF-κB and inducing IL-8 without restoring CagA translocation. The CagA translocation-independent, CagL-dependent IL-8 induction involved host signalling via integrin α5 β1 , Src kinase, the mitogen-activated protein kinase (MAPK) pathway and NF-κB but was independent of NOD1. Our findings reveal a novel pathway whereby CagL, via interaction with host integrins, can trigger pro-inflammatory responses independently of CagA translocation or NOD1 signalling.