Mucosal Degradation Research Articles

Stability Engineering of Recombinant Secretory IgA.

Secretory IgA (SIgA) presents a promising avenue for mucosal immunotherapy yet faces challenges in expression, purification, and stability. IgA exists in two primary isotypes, IgA1 and IgA2, with IgA2 further subdivided into two common allotypes: IgA2m(1) and IgA2m(2). The major differences between IgA1 and IgA2 are located in the hinge region, with IgA1 featuring a 13-amino acid elongation that includes up to six O-glycosylation sites. Furthermore, the IgA2m(1) allotype lacks a covalent disulfide bond between heavy and light chains, which is present in IgA1 and IgA2m(2). While IgA1 demonstrates superior epitope binding and pathogen neutralization, IgA2 exhibits enhanced effector functions and stability against mucosal bacterial degradation. However, the noncovalent linkage in the IgA2m(1) allotype raises production and stability challenges. The introduction of distinct single mutations aims to facilitate an alternate disulfide bond formation to mitigate these challenges. We compare four different IgA2 versions with IgA1 to further develop secretory IgA antibodies against SARS-CoV-2 for topical delivery to mucosal surfaces. Our results indicate significantly improved expression levels and assembly efficacy of SIgA2 (P221R) in Nicotiana benthamiana. Moreover, engineered SIgA2 displays heightened thermal stability under physiological as well as acidic conditions and can be aerosolized using a mesh nebulizer. In summary, our study elucidates the benefits of stability-enhancing mutations in overcoming hurdles associated with SIgA expression and stability.

Rosa Roxburghii Tratt Fruit Extract Prevents Dss-Induced Ulcerative Colitis in Mice by Modulating the Gut Microbiota and the IL-17 Signaling Pathway

Ulcerative colitis (UC) is a non-specific inflammatory bowel illness characterized by intestinal mucosal barrier degradation, inflammation, oxidative damage, and gut microbiota imbalances. Rosa roxburghii Tratt Fruit extract (RRTE) was extracted from Rosa roxburghii Tratt fruit, exhibiting an excellent prevention effect against UC; RRTE could prevent the damage of DSS-induced human normal colonic epithelial (NCM 460) cells, especially in cell viability and morphology, and oxidative damage. Additionally, in UC mice, RRTE could limit the intestinal mucosal barrier by increasing the expression of intestinal tight junction proteins and mucin, reducing inflammation and oxidative damage in colon tissue. More importantly, RRTE can increase the abundance of beneficial bacteria to regulate gut microbiota such as Ruminococcus, Turicibacter, and Parabacteroides, and reduce the abundance of harmful bacteria such as Staphylococcus and Shigella. Furthermore, transcriptomics of colonic mucosal findings point out that the beneficial effect of RRTE on UC could be attributed to the modulation of inflammatory responses such as the IL-17 and TNF signaling pathways. The qPCR results confirm that RRTE did involve the regulation of several genes in the IL-17 signaling pathway. In conclusion, RRTE could prevent DSS-induced damage both in vitro and in vivo.

Corrigendum to: Mucosal glycan degradation of the host by the gut microbiota.

Corrigendum to: Mucosal glycan degradation of the host by the gut microbiota.

Role of MR enterography versus ileo-colonoscopy in the assessment of inflammatory bowel diseases

BackgroundInflammatory bowel disease (IBD) is widespread and rapidly rising in developing countries. It remains a significant issue in Western culture with a prevalence of more than 0.3%. Symptom control has been the only focus of treatment before the discovery that many individuals with IBD continue to have disease activity even in the absence of clinical symptoms. Therefore, treatment goals now include establishing clinical remission, steroid-free remission, and mucosal healing, which may eventually be complemented by transmural healing in cross-sectional imaging modalities. Magnetic resonance enterography (MRE), computed tomography enterography, and small-bowel ultrasound are now reliable methods for staging intramural lesions and extramural consequences in CD and for determining disease activity and severity. Recently literature suggests the incorporation of (MRE) for periodic reevaluation of IBD patients, as it offers small-bowel, colonic, and extra-enteric assessment as well as monitors the response to the anti-inflammatory therapy. The purpose of the current study was to compare MRE with ileo-colonoscopy findings in the diagnosis of IBD features, specifically Crohn's disease, and ulcerative colitis, as well as in the detection of disease exacerbation (Activity).ResultsThis study used MRE and ileo-colonoscopy to assess chronic inflammatory bowel disease patients; the patient population (n = 30) was made up of (14/30, 46.7%) females and (16/30, 53.3%) males, with a mean age of 32 ± SD 13 years. MRE alone detected lymphadenopathy in 73.3% of patients, and mural thickening with a mean of 4.1 ± SD 5.1 mm. It has detected mucosal enhancement with 80% sensitivity and 60% specificity. However, it was unable to detect mucosal erosions or ulceration.ConclusionsMRE is sensitive, inexpensive, noninvasive, and radiation-free for inflammatory bowel disease detection, with 86.7% diagnostic accuracy for affected areas. Unlike ileo-colonoscopy, it could examine the entire small intestine, precisely measure the affected loop, and detect activity signs such as mural thickening and lymphadenopathy. Only ileo-colonoscopy could detect mucosal degradation and superficial ulcers. IBD treatment protocols should incorporate MRE for small-bowel, colonic, and extra-enteric assessment, monitoring of disease activity, and anti-inflammatory therapy response.

Dietary Resin Acid Concentrate Improved Performance of Broiler Chickens and Litter Quality in Three Experiments.

Simple SummaryResin acids are antimicrobial and anti-inflammatory compounds derived from spruce and pine trees. In a previous study, in which a mixture of resin acids and fatty acids from pine and spruce trees was added to the feeds of broiler chickens, they grew heavier, and their footpads stayed in better condition. Here, three separate trials were conducted to study whether dietary resin acids without the fatty acids have the same effects on broiler chickens. Broiler chicken diets were amended with different dosages of a resin acid concentrate product. Bird weight gain increased, and the efficiency of broiler production was improved when the resin acid concentrate was added to the diet at 125–250 g/ton. The litter material of pens stayed drier in resin acid concentrate groups, which may indicate better intestinal condition of the birds. However, the footpad condition was unaffected by the experimental diets. The results suggest that the resin acid concentrate improves bird weight gain and the efficiency of broiler production. Therefore, the resin acid concentrate may be a promising feed additive for broiler chickens.Dietary coniferous resin acids have previously been suggested to support the intestinal integrity of broiler chickens by reducing mucosal collagen degradation. The present study examined the effects of resin acid concentrate (RAC) on broiler performance and litter quality. In trial 1, RAC was added to diets at 0, 125, 250, or 1250 g/ton, while in trials 2 and 3, RAC dosing was 0 or 175 g/ton. Bird weight, feed consumption, mortality, feed conversion ratio (FCR), European Efficiency Index (EEI), litter moisture, and footpad dermatitis (FPD) lesions were measured. In trial 1, RAC at 125 and 250 g/ton improved weight gain and EEI, while RAC at 1250 g/ton group did not differ from control. Feed consumption, FCR, FPD scores and mortality were similar in all treatments, but litter quality was improved by all doses of RAC. In trials 2 and 3, RAC increased the final weight of birds, improved FCR, EEI, and litter quality, but had no effects in other parameters. In summary, RAC at 125–250 g/ton improved bird performance and thus shows promise as a feed additive. The dryer litter in RAC treatments may suggest improved intestinal condition as a response to in-feed resin acids.

Vaginal sialoglycan foraging by Gardnerella vaginalis: mucus barriers as a meal for unwelcome guests?

Bacterial vaginosis (BV) is a condition of the vaginal microbiome in which there are few lactobacilli and abundant anaerobic bacteria. Members of the genus Gardnerella are often one of the most abundant bacteria in BV. BV is associated with a wide variety of poor health outcomes for women. It has been recognized since the 1980s that women with BV have detectable and sometimes markedly elevated levels of sialidase activity in vaginal fluids and that bacteria associated with this condition produce this activity in culture. Mounting evidence collected using diverse methodologies points to the conclusion that BV is associated with a reduction in intact sialoglycans in cervicovaginal secretions. Here we review evidence for the contributions of vaginal bacteria, especially Gardnerella, in the processes of mucosal sialoglycan degradation, uptake, metabolism and depletion. Our understanding of the impacts of vaginal sialoglycan degradation is still limited. However, the potential implications of sialic acid depletion are discussed in light of our current understanding of the roles played by sialoglycans in vaginal physiology.

Metalloproteinases in Inflammatory Bowel Diseases.

Inflammatory bowel diseases (IBD) are chronic inflammatory diseases of the gastrointestinal tract, encompassing two main disorders: Crohn’s disease (CD) and ulcerative colitis (UC). In both these pathologies, excessive and local immune response against luminal antigens promotes a pathological process leading to various degrees of gut damage. Matrix metalloproteinases (MMPs) are a family of neutral proteases with the ability to degrade all components of extracellular matrix. In physiological conditions, MMPs are produced at very low level and generally in the latent form and are involved in the normal tissue turnover. Their function is inhibited by tissue inhibitors of metalloproteinases (TIMPs). However, in inflamed tissue of IBD patients, MMPs are produced in excess and/or the activity of TIMPs is not sufficient to block MMPs, thereby making a major contribution to the IBD-related mucosal degradation. In this review, we summarize the available evidence on the expression and role of MMPs in IBD.

Mucosal glycan degradation of the host by the gut microbiota.

The gut microbiota plays a major role in human health and an alteration in gut microbiota structure and function has been implicated in several diseases. In the colon, mucus covering the epithelium is critical to maintain a homeostatic relationship with the gut microbiota by harboring a microbial community at safe distance from the epithelium surface. The mucin glycans composing the mucus layer provide binding sites and a sustainable source of nutrients to the bacteria inhabiting the mucus niche. Access to these glycan chains requires a complement of glycoside hydrolases (GHs) produced by bacteria across the phyla constituting the human gut microbiota. Due to the increased recognition of the role of mucus-associated microbes in human health, how commensal bacteria breakdown and utilize host mucin glycans has become of increased interest and is reviewed here. This short review provides an overview of the strategies evolved by gut commensal bacteria to access this rich source of the nutrient with a focus on the GHs involved in mucin degradation.

The big problem with microplastic pollution

Plastic pollution is one of the most pervasive and sinister ecological threats worldwide. Most of us are aware of animals ingesting and dying from plastic waste. However, much less is known of the more insidious problem caused by much smaller microplastics, which are formed after larger pieces of plastic are degraded, by sunlight or wave action, into very tiny particles. Owing to their size, microplastics are extremely difficult to remove from the environment and are easily consumed by animals, yet their biological effects are unclear. For these reasons, Giacomo Limonta and scientists from the Universities of Siena and Ferrara, Italy, wanted to know the various ways in which microplastics impact animals, from their miniscule DNA molecules to their ability to move.The team tested the effect of two plastics – polyethylene (the principal source of microplastic globally) and toxic polystyrene – on a standard laboratory animal, the zebrafish. They exposed the fish to microplastics that were smaller than one-tenth of a millimetre, at concentrations similar to those found in highly polluted waters, for 20 days, before looking at how the plastics affected the fish's gills and intestines, their movement and the gene-expression patterns of their liver. The researchers focused on the liver because it detoxifies blood and contributes to immune function, while the intestine absorbs nutrients into the body and the gills are necessary for breathing. To identify how microplastics changed the structure of the gills and intestine, the researchers stained the tissues and scrutinised them under a microscope. Lastly, they used infrared sensors to observe how the pollution affected the fish's swimming behaviour.Overall, the microplastics severely compromised the zebrafish's immunity. For instance, microplastics elevated the activity of genes that help certain immune cells (lymphocytes) recognise liver tissue and trigger immune responses. This worrying finding suggests that the fish's own immune system could mount overzealous attacks on the liver, impairing its function. In addition, the team realised that germs might be able to infiltrate liver cells more easily, because genes linked to antimicrobial resistance and cell-to-cell attachment were less active. Meanwhile, genes for metabolic pathways that manage fat in the fish's bodies – including those for cholesterol and fatty-acid synthesis – were turned down. Given the importance of these molecules for immunity, the authors suggest that microplastics could seriously affect the fish's ability to fight off infections.The microscopic analysis also showed the layer of cells (mucosa) covering the intestine and gills was profoundly weakened by microplastics. Indeed, the intestine showed evidence of mucosal degradation (a sign of tissue damage) and it had fewer mucus-producing cells (goblet cells) essential for intestinal function. In the gills, the microplastics thickened the secondary lamellae (the flap structures where gases pass into and out of the body) and caused excessive mucus secretion, which together increases the distance the gasses travel to and from the bloodstream. Additionally, the microplastics elevated the number of neutrophils (immune cells) that respond to inflammation and kill bacteria in the gills and intestine, pointing to severe microbial infection. And when the team monitored the zebrafish's activity levels, the microplastics made them unusually active at night, indicating the damaging effect that these particles can have on an animal's internal clock.This study demonstrates that microplastics perversely impact all aspects of an animal's biology, from gene expression to first and secondary lines of defence against infection and their body clock. Considering the critical roles these play in everyday survival, microplastics have the potential to imperil whole populations of animals and wreak havoc on ecosystems. The alarming discoveries presented by the authors are yet another warning of the dangers of pollution and the need to reduce plastic use.

Candida albicans induces mucosal bacterial dysbiosis that promotes invasive infection.

Infectious complications are a common cause of morbidity and mortality in cancer patients undergoing chemotherapy due to increased risk of oral and gastrointestinal candidiasis, candidemia and septicemia. Interactions between C. albicans and endogenous mucosal bacteria are important in understanding the mechanisms of invasive infection. We published a mouse intravenous chemotherapy model that recapitulates oral and intestinal mucositis, and myelosuppression in patients receiving 5-fluorouracil. We used this model to study the influence of C. albicans on the mucosal bacterial microbiome and compared global community changes in the oral and intestinal mucosa of the same mice. We validated 16S rRNA gene sequencing data by qPCR, in situ hybridization and culture approaches. Mice receiving both 5Fu and C. albicans had an endogenous bacterial overgrowth on the oral but not the small intestinal mucosa. C. albicans infection was associated with loss of mucosal bacterial diversity in both sites with indigenous Stenotrophomonas, Alphaproteobacteria and Enterococcus species dominating the small intestinal, and Enterococcus species dominating the oral mucosa. Both immunosuppression and Candida infection contributed to changes in the oral microbiota. Enterococci isolated from mice with oropharyngeal candidiasis were implicated in degrading the epithelial junction protein E-cadherin and increasing the permeability of the oral epithelial barrier in vitro. Importantly, depletion of these organisms with antibiotics in vivo attenuated oral mucosal E-cadherin degradation and C. albicans invasion without affecting fungal burdens, indicating that bacterial community changes represent overt dysbiosis. Our studies demonstrate a complex interaction between C. albicans, the resident mucosal bacterial microbiota and the host environment in pathogenesis. We shed significant new light on the role of C. albicans in shaping resident bacterial communities and driving mucosal dysbiosis.

Mucosal trapping and degradation of Nippostrongylus brasiliensis occurs in the absence of STAT6

Hookworms represent a major infectious burden globally, especially in developing countries. The murine hookworm Nippostrongylus brasiliensis is normally cleared in a manner dependent on IL-13, IL4-R and STAT6 signalling. Here we have used STAT6-deficient animals to model a non-resistant population and describe 2 novel STAT6-independent processes for the clearance of N. brasiliensis. During primary infection STAT6-/- animals are able to clear gut-dwelling N. brasiliensis by a mechanism involving the trapping and degradation of worms in the gut mucosa. Here, a previously undescribed STAT6-independent up-regulation of Relm-β was observed which correlated with the mucosal trapping and degradation of worms. Previous studies have indicated that during secondary infection STAT6 deficient animals fail to expel adult worms and remain susceptible to re-infection and long-term colonization of the gut. We report here that an initial partially protective response occurs early upon re-infection in the absence of STAT6, and that a late-phase protective secondary response arises in the gut of STAT6-deficient mice leading to the clearance of the majority of N. brasiliensis, through their trapping and death in the mucosal layer of the lower region of the small intestine. These findings show that there are a number of redundant effector pathways which act to reduce worm burden in the gut which can be activated by mechanisms that do not work through the dominant STAT6 signalling pathway and may be useful as targets for future vaccination strategies against resistant hookworm strains.

Human oral keratinocyte E-cadherin degradation byCandida albicansandCandida glabrata

E-cadherin (E-Cad) is a 120-kDa adhesive protein found in adherens junctions of the digestive tract epithelium. We tested the ability of two Candida strains to degrade human E-Cad in the Candida virulence factor perspective. We set out to study oral mucosal E-Cad degradation by clinical and reference strains of Candida albicans and Candida glabrata. We also included hyphal and secreted aspartic proteinase (Sap) mutants of C. albicans to test the effect of yeast/hyphal transition on the ability to degrade E-Cad. The tests were performed at pH 4 and pH 6 to determine the effect of local tissue acidity on the activation of Saps. The C. albicans strains used were: CCUG 32723; clinical strain SC5314 which is known to be strongly invasive; hyphal mutants of SC5314: HLC52 (efg1/efg1), HLC54 (cph1/cph1 efg1/efg1) and JKC19 (cph1/cph1); clinical strain B1134; Sap 1-3 and Sap 4-6 mutants of SC5314. The C. glabrata strains used were ATCC 90030, and the clinical strains 5WT and G212. The sonicated yeast cells of C. albicans JKC19 and SC5314, both in hyphal form, degraded E-Cad at pH 4. The 10x concentrated growth media of the strains HLC-52, HLC-54, 32723 and B1134; all in yeast form, caused degradation at pH 4, HLC-52 and HLC-54 also at pH 6. The C. glabrata strains did not degrade E-Cad. pH is a strain dependent triggering factor in activating yeast or hyphal form related Candida Saps in degrading epithelial cell associated E-Cads.

Nanoparticle-based vaginal drug delivery systems for HIV prevention

Importance of the Field: Several strategies are being investigated for the prevention of heterosexual transmission of HIV. Of these, topical vaginal drug delivery systems, microbicides, are being actively pursued. HIV prevention by means of a topical microbicide has several drug delivery challenges. These challenges include the vaginal mucosal barriers and potential degradation of the drugs in the vaginal lumen due to pH and enzymes present. Also, new drugs being evaluated as microbicides have specific mechanisms of action, which in some cases require drug targeting to a specific site of action. Nanoparticles provide a delivery strategy for targeted or controlled delivery to the vagina which can be applied in the field of HIV prevention.Areas covered in the review: This review summarizes nanoparticulate systems and their use in mucosal delivery to date. The sexual transmission of HIV along with the various targets to prevent transmission are discussed as well as the potential opportunities, challenges and advantages in using a nanoparticle-based approach for microbicidal drug delivery.What the reader will gain: This review provides a general understanding of vaginal drug delivery, its challenges, and nanoparticulate delivery systems. Additionally, insight will be gained as to the limited existing application of this technology to the field of HIV prevention.Take home message: To date, few studies have been published that exploit nanoparticle-based microbicidal delivery to the vagina. The use of nanoparticles for vaginal drug delivery provides an approach to overcome the existing barriers to success.

Decreased Histamine Catabolism in the Colonic Mucosa of Patients with Colonic Adenoma

Alterations in mucosal histamine degradation play an important role in various gastrotinestinal diseases including colonic adenoma. In humans, histamine can be catabolized either by oxidative deamination by diamine oxidase (DAO) or by ring methylation by histamine N-methyltransferase (HNMT). The significance of HNMT in this context was investigated for the first time in this project. About 94 colonic biopsies were endoscopically obtained from 23 patients suffering from colonic adenoma and 26 biopsies from six healthy individuals. Each sample was mechanically homogenized, homogenates were cleared by centrifugation and used for determination of protein and histamine concentrations and enzyme activities of DAO and HNMT by radiometric assay. In adenoma patients DAO activities were slightly and HNMT activities were significantly decreased in normal mucosa compared to controls. Activities of both enzymes were significantly lower in adenoma tissue than in healthy mucosa in the same patients. A significant correlation was found between HNMT and DAO in all investigated samples. Histamine concentrations were elevated in adenoma patients. Histamine catabolism is decreased in the colonic mucosa of patients with colonic adenoma.

Myofibroblast Matrix Metalloproteinases Activate the Neutrophil Chemoattractant CXCL7 From Intestinal Epithelial Cells

The up-regulation of matrix metalloproteinases (MMPs) in the inflamed gut has mainly been associated with mucosal degradation and ulceration. However, their in vitro capacity to specifically cleave inflammatory mediators indicates that MMPs may have a profound immunoregulatory impact. We hypothesized that MMPs proteolytically modify intestinal epithelial chemokine signaling. Interleukin-1beta-stimulated Caco-2 cells were exposed basolaterally to nanomolar concentrations of activated MMP-3 or cocultured with interleukin-1beta-stimulated, MMP-producing, colonic myofibroblasts (CCD-18co). The conditioned media were subjected to chemotaxis assays. In addition, epithelial cells from patients with colitis were examined by real-time polymerase chain reaction, immunoblotting, and immunohistochemistry. MMP-3 dose-dependently induced the neutrophil (up to 5-fold) but not monocyte chemoattractant capacity of Caco-2 cells. A similar Caco-2 chemotactic response was obtained in the Caco-2/CCD-18co cocultures. The principal mediator of these protease-related effects was identified as the potent neutrophil chemokine CXCL7 (neutrophil activating peptide 2), a proteolytic cleavage product of chemotactically inert platelet basic protein (PBP), not previously identified in the intestine. Antibodies against CXCL7 inhibited the MMP-induced chemotactic response by 84%, and PBP mRNA and protein were detected in stimulated Caco-2 but not in CCD-18co cells. Furthermore, PBP transcript and protein levels were low in the mucosa and in isolated epithelial cells from patients with Crohn's disease and from normal intestine but increased up to 13-fold in patients with ulcerative colitis. These findings identify a novel proinflammatory action of MMPs in inflammation and suggest that lamina propria myofibroblasts are required to achieve maximal intestinal epithelial immune activation.

Significance of cell-surface expression of matrix metalloproteinases and their inhibitors on gastric epithelium and infiltrating mucosal lymphocytes in progression of helicobacter pylori-associated gastritis

Background: Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) have recently been shown to be important in tissue breakdown and remodeling in gut with inflammatory bowel disease. The role of MMPs and TIMPs remains largely unexplored in Helicobacter pylori-associated gastritis (HAG). The aim of this study was to investigate the expression of these proteolytic enzymes in HAG. Methods: Cell-surface or/and intracellular expression of MMP-2, 7, 9 and MT1-MMP and TIMPs (TIMP-2 and -4) was determined in gastric epithelium and infiltrative mucosal lymphocytes (IML) in single endoscopic biopsies from H. pylori-infected (n = 25) and uninfected (n = 15) patients. The quantitative analysis was based on the percentage of positive cells detected by flow cytometry. Results: Secreted MMPs and TIMPs as well as membrane type 1-MMP were shown to be localized mainly on the cell surface of both epithelial cells and IML in HAG. H. pylori significantly up-regulated the cell-surface expression not only of MMPs, but also of TIMPs on IML within tissues. The expression of these molecules on IML was correlated with the grade of gastritis. Conclusions: MMPs and TIMPs expressed on gastric epithelium and H. pylori-antigen(s)-stimulated IML may be implicated in mucosal degradation and remodeling of the stomach. These might contribute to the pathogenesis and progression of atrophy and intestinal metaplasia of gastric mucosa.

Intestinal protein and LPH synthesis in parenterally fed piglets receiving partial enteral nutrition and enteral insulinlike growth factor 1.

Providing partial enteral nutrition (PEN) supplemented with insulinlike growth factor-1 (IGF-1) to parenterally fed piglets increases lactase-phlorizin hydrolase (LPH) activity, but not LPH mRNA. The current aim was to investigate potential mechanisms by which IGF-1 up-regulates LPH activity. Newborn piglets (n = 15) received 100% parenteral nutrition (TPN), 80% parenteral nutrition + 20% parenteral nutrition (PEN), or PEN + IGF-1 (1.0 mg. kg-1. d-1) for 7 days. On day 7, [2H3]-leucine was intravenously administered to measure mucosal protein and brush border LPH (BB LPH) synthesis. Weight gain, nutrient intake, and jejunal weight and length were similar among the treatment groups. Partial enteral nutrition alone increased mucosal weight, villus width and cross-sectional area, LPH activity, mRNA expression, and high mannose LPH precursor (proLPHh) abundance compared with TPN (P<0.05). Insulinlike growth factor-1 further increased mucosal weight, LPH activity, and LPH activity per unit BB LPH approximately twofold over PEN alone (P < 0.05) but did not affect LPH mRNA or the abundance of proLPHh (one of the LPH isoforms) or mature LPH. Isotopic enrichment of [2H3]-leucine in plasma, mucosal protein, and LPH precursors, and the fractional and absolute synthesis rates of mucosal protein and LPH were similar among the treatment groups. Insulinlike growth factor-1 treatment increased total mucosal protein synthesis (60%, P < 0.05) but not LPH synthesis compared with the other two groups. Because IGF-1 did not affect the fractional synthesis rate of either mucosal protein or LPH, the authors suggest that enteral IGF-1 increases mucosal protein mass and LPH activity by suppressing mucosal proteolytic degradation.

Intestinal Protein and LPH Synthesis in Parenterally Fed Piglets Receiving Partial Enteral Nutrition and Enteral Insulinlike Growth Factor 1

ABSTRACTBackgroundProviding partial enteral nutrition (PEN) supplemented with insulinlike growth factor‐1 (IGF‐1) to parenterally fed piglets increases lactase–phlorizin hydrolase (LPH) activity, but not LPH mRNA. The current aim was to investigate potential mechanisms by which IGF‐1 up‐regulates LPH activity.MethodsNewborn piglets (n = 15) received 100% parenteral nutrition (TPN), 80% parenteral nutrition + 20% parenteral nutrition (PEN), or PEN + IGF‐1 (1.0 mg · kg−1 · d−1) for 7 days. On day 7, [2H3]‐leucine was intravenously administered to measure mucosal protein and brush border LPH (BB LPH) synthesis.ResultsWeight gain, nutrient intake, and jejunal weight and length were similar among the treatment groups. Partial enteral nutrition alone increased mucosal weight, villus width and cross‐sectional area, LPH activity, mRNA expression, and high mannose LPH precursor (proLPHh) abundance compared with TPN (P &lt;0.05). Insulinlike growth factor‐1 further increased mucosal weight, LPH activity, and LPH activity per unit BB LPH approximately twofold over PEN alone (P &lt; 0.05) but did not affect LPH mRNA or the abundance of proLPHh (one of the LPH isoforms) or mature LPH. Isotopic enrichment of [2H3]‐leucine in plasma, mucosal protein, and LPH precursors, and the fractional and absolute synthesis rates of mucosal protein and LPH were similar among the treatment groups. Insulinlike growth factor‐1 treatment increased total mucosal protein synthesis (60%, P &lt; 0.05) but not LPH synthesis compared with the other two groups.ConclusionsBecause IGF‐1 did not affect the fractional synthesis rate of either mucosal protein or LPH, the authors suggest that enteral IGF‐1 increases mucosal protein mass and LPH activity by suppressing mucosal proteolytic degradation.

Tracheoesophageal fistula from an indwelling endotracheal tube balloon: a report of two cases and review

Tracheoesophageal fistula (TEF) is a rare but potentially life-threatening complication of prolonged endotracheal intubation. Fewer than a dozen cases of cuff-induced TEF have been reported since 1975. 1 Hilgenberg AD Grillo HC. Acquired nonmalignant tracheoesophageal fistula. J Thorac Cardiovasc Surg. 1983; 85: 492-498 PubMed Google Scholar , 2 Marzelle J Dartevelle P Khalife J Rojas-Miranda A Chapelier A Levasseur P. Surgical management of acquired post-intubation tracheo-oesophageal fistulas: 27 patients. Eur J Cardiothorac Surg. 1989; 3: 499-502 Crossref PubMed Scopus (46) Google Scholar , 3 Tan KK Lee JK Sarvesvaran R. Acquired tracheoesophageal fistula following tracheal intubation in a burned patient. Burns. 1993; 19: 360-361 Abstract Full Text PDF PubMed Scopus (8) Google Scholar , 4 Amodei C Pompili L Cianconi G Gaddi M Giuliani A Biddau A. Description of a case of tracheoesophageal fistula following endotracheal intubation. 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Br J Anaesth. 1976; 48: 105-109 Crossref PubMed Scopus (21) Google Scholar Indwelling rigid nasogastric tubes (NGT) have long been known to exacerbate esophageal mucosal degradation and necrosis with resultant fistula formation. 7 Kamen JM Wilkinson CJ. A new low-pressure cuff for endotracheal tubes. Anesthesiology. 1971; 34: 482-485 Crossref PubMed Scopus (31) Google Scholar , 8 Thomas AN. The diagnosis and treatment of tracheoesophageal fistula caused by cuffed tracheal tubes. J Thorac Cardiovasc Surg. 1973; 65: 612-619 PubMed Google Scholar , 9 MacKenzie CF Klose S Browne DRG. A study of inflatable cuffs on endotracheal tubes. Br J Anaesth. 1976; 48: 105-109 Crossref PubMed Scopus (21) Google Scholar , 10 Geha AS Seegers JV Kodner IJ Lefrak S. Tracheoesophageal fistula caused by cuffed tracheal tube: successful treatment by tracheal resection and primary repair with four-year follow-up. 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Enhancing lamina propria Th1 cell responses with interleukin 12 produces severe tissue injury

Background & Aims: Interleukin (IL)-12 is believed to modulate local T-cell response in human colitis. A direct functional relationship between IL-12 and tissue injury in human intestine has not been reported. The aim of this study was to examine changes that take place in explant cultures of human fetal gut after stimulation of T cells with anti-CD3 in the presence of exogenous IL-12/IL-18. Methods: T cells in explants of fetal gut were activated with anti-CD3 antibody and/or IL-12 or IL-18. Mucosal pathology was determined by immunohistochemistry. Quantitative reverse-transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay were used to determine cytokine synthesis, and the production of matrix metalloproteinases was analyzed by RT-PCR and Western blotting. Results: Activation of T cells in explants with anti-CD3 antibody elicited very little interferon (IFN)-γ and tumor necrosis factor (TNF)-α production and no tissue injury. Addition of graded doses of IL-12 with anti-CD3 resulted in a significant increase in both IFN-γ and TNF-α. This change was associated with a massive increase in stromelysin-1 expression and severe tissue injury, which was inhibitable by a stromelysin-1 inhibitor. Costimulation of explants with anti-CD3 and IL-18 induced only IFN-γ and no tissue injury. Conclusions: IL-12 can convert a physiological T-cell signal into a strong signal with the downstream effect of elevating tissue stromelysin-1 concentration and mucosal degradation. GASTROENTEROLOGY 1999;117:1069-1077