Differential properties of mucous glycoproteins in rat nasal epithelium. A comparison between allergic inflammation and lipopolysaccharide stimulation

Oat Peptides Alleviate Dextran Sulfate Sodium Salt-Induced Colitis by Maintaining the Intestinal Barrier and Modulating the Keap1-Nrf2 Axis

The prevalence of inflammatory bowel disease (IBD) is progressively rising each year, emphasizing the significance of implementing rational dietary interventions for disease prevention. Oats, being a staple agricultural product, are abundant in protein content. This study aimed to investigate the protective effects and underlying mechanisms of oat peptides (OPs) in a mouse model of acute colitis induced by dextran sulfate sodium salt (DSS) and a Caco-2 cell model. The findings demonstrated that intervention with OPs effectively mitigated the symptoms associated with DSS-induced colitis. The physicochemical characterization analysis demonstrated that the molecular weight of the OPs was predominantly below 5 kDa, with a predominant composition of 266 peptides. This study provides further evidence of the regulatory impact of OPs on the Keap1-Nrf2 signaling axis and elucidates the potential role of WGVGVRAERDA as the primary bioactive peptide responsible for the functional effects of OPs. Ultimately, the results of this investigation demonstrate that OPs effectively mitigate DSS-induced colitis by preserving the integrity of the intestinal barrier and modulating the Keap1-Nrf2 axis. Consequently, these findings establish a theoretical foundation for the utilization of OPs as dietary supplements to prevent the onset of IBD.

Integrated Microbiome and Metabolomic Analysis Reveal the Repair Mechanisms of Ovalbumin on the Intestine Barrier of Colitis Mice

The development and progression of colitis would detrimentally destroy the intestine barrier. However, there remains a paucity of evidence on whether ovalbumin (OVA) can be used as a nutritional food protein to repair the intestinal barrier. In this study, the repairing mechanism of OVA on intestinal barrier was thoroughly investigated by gut microbiota and untargeted metabolomics techniques. The findings demonstrated that OVA reduced intestinal permeability and restored mucin (0.75 ± 0.06) and tight junction (TJ) protein (0.67 ± 0.14) expression in colitis mice caused by 3% dextran sulfate sodium (DSS). In addition, the inflammation response and oxidative stress were also attenuated. The intake of OVA upregulated the abundance of Lactobacillaceae (7.60 ± 3.34%) and Akkermansiaceae (10.39 ± 5.97%). Furthermore, OVA upregulated the abundance of inosine (6.06 ± 0.36%), putrescine (4.14 ± 0.20%), and glycocholic acid (5.59 ± 0.23%) in colitis mice through ATP binding cassette (ABC) transporters and bile secretion pathways. In summary, our findings revealed that OVA could maintain intestinal health, which may provide crucial insights for preventing and treating intestinal diseases.

Investigation of the Relationship Between Trefoil Factor Family Peptides and Sinonasal Inflammation

The trefoil factor family (TFF) is a relatively new family of peptides. In some studies, an association between trefoil factors and inflammatory diseases of the nasal and paranasal sinuses has been suggested. However, it is still not clear whether there is a relationship between trefoil peptides and inflammation of the respiratory tract. The aims of this study are to determine the presence of TFF1, TFF2, and TFF3 in the nasal mucosa and investigate their relationships with inflammation by using rat models of various sinonasal inflammations. Nasal tampon, lipopolysaccharide, and ovalbumin were used to generate rat models of sinonasal inflammation, i.e., rhinosinusitis and allergic rhinitis. The study was conducted on seventy rats in seven groups, each with ten rats: four groups with rhinosinusitis, two groups with allergic rhinitis, and a control group. Histological evaluation of sinonasal mucosa from all rats was performed, and Trefoil factors were investigated using immunohistochemical methods. All three TFF peptides were detected in rat nasal mucosa by histological evaluation. No significant differences in the trefoil factor scores were observed among the study groups. A significant correlation between the TFF1 and TFF3 scores and loss of cilia was identified (p < 0.05). In conclusion, no direct relationship between sinonasal inflammation and TFF scores was observed. However, a possible association between the TFF and epithelial damage or regeneration in sinonasal inflammation can be suggested based on the correlation observed between the TFF1 and TFF3 scores and scores of cilia loss.

Citrus peel ameliorates mucus barrier damage in HFD-fed mice

Citrus peel is rich in bioactive components, especially polyphenols, which are considered to have great potential in the prevention of intestinal diseases. The intestinal mucus barrier is the first defense against the invasion of foreign substances. In this study, we aimed to explore the possibility and mechanism of citrus peel in alleviating the mucus barrier damage in high-fat-diet (HFD) mice. We found that citrus peel powder (CPP) supplementation effectively reduced body weight, fat weight, intestinal permeability, hyperlipidemia, and systemic inflammation in HFD-fed mice. In particular, CPP increased the number of goblet cells, the protein expression of Mucin-2 (Muc2), and the thickness of the mucus layer, thereby strengthening the colonic mucus barrier function. Moreover, CPP supplementation also reduced the expression of endoplasmic reticulum stress (ERS) proteins (GRP78 and CHOP) and increased the expression of T-synthase (O-glycosylation rate-limiting enzyme) and its chaperone protein (Cosmc) in the colon of HFD-fed mice, which suggested that CPP could improve the abnormal protein folding and O-glycosylation of Muc2 during processing and modification. In summary, our study indicates that CPP plays an effective role in relieving mucus barrier damage by improving the production and properties of Muc2, providing new perspectives on the development of CPP as a dietary supplement for strengthening the intestinal barrier.

3D printed transwell-integrated nose-on-chip model to evaluate effects of air flow-induced mechanical stresses on mucous secretion

While there are many chip models that simulate the air-tissue interface of the respiratory system, only a few represent the upper respiratory system. These chips are restricted to unidirectional flow patterns that are not comparable to the highly dynamic and variable flow patterns found in the native nasal cavity. Here we describe the development of a tunable nose-on-chip device that mimics the air-mucosa interface and is coupled to an air delivery system that simulates natural breathing patterns through the generation of bi-directional air flow. Additionally, we employ computational modeling to demonstrate how the device design can be tuned to replicate desired mechanical characteristics within specific regions of the human nasal cavity. We also demonstrate how to culture human nasal epithelial cell line RPMI 2650 within the lab-on-chip (LOC) device. Lastly, Alcian Blue histological staining was performed to label mucin proteins, which play important roles in mucous secretion. Our results revealed that dynamic flow conditions can increase mucous secretion for RPMI 2650 cells, when compared to no flow, or stationary, conditions.

Hydrogen: A Potential New Adjuvant Therapy for COVID-19 Patients

Hydrogen has been shown to have antioxidant, anti-inflammatory, hormone-regulating, and apoptosis-resistance properties, among others. Based on a review of the research, the use of hydrogen might reduce the destructive cytokine storm and lung injury caused by SARS-CoV-2 during COVID-19 (Corona Virus Disease 2019) in the early stage, stimulating ropy sputum drainage, and ultimately reducing the incidence of severe disease. Molecular hydrogen treatment has the potential to become a new adjuvant therapy for COVID-19, but its efficacy and safety require large clinical trials and further confirmation.

Puerarin Rebuilding the Mucus Layer and Regulating Mucin-Utilizing Bacteria to Relieve Ulcerative Colitis

The colonic mucus barrier serves as a primary defense against enteric pathogens; destruction of this mucus layer has been observed in ulcerative colitis patients. This study aims to investigate the possibility of rebuilding the colon mucus layer through puerarin supplementation, which can stimulate mucin secretion and goblet cells differentiation. After puerarin supplementation, the thickness of colon mucus layer was increased and the permeability was reduced. The erosion of intestinal epithelium by bacteria was blocked, and the loss of epithelial integrity was alleviated. Puerarin also altered the composition of mucin-utilizing bacteria, which influenced the mucus permeability. Levels of short-chain fatty acids (SCFAs) were increased after puerarin supplementation, which as a direct source of energy for the proliferation of epithelia and goblet cells. This study demonstrated that enhancement of mucin secretion to relieve ulcerative colitis (UC) by puerarin supplementation is feasible, and the regulation of mucin-utilizing bacteria and the increased levels of SCFAs may be the main reasons.

Laryngeal inflammation in the sudden infant death syndrome

OBJECTIVE

Sudden infant death syndrome (SIDS) is marked by 'the sudden death of an infant that is unexpected by history and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation'. The cause is unknown. Excessive subglottic submucosal glandular tissue and excessive sulphated mucus glycoprotein in the larynges of SIDS babies have been previously reported from our institution. We now report on laryngeal immunohistology.

METHODS

Larynges from 7 children who died from Sudden Infant Death Syndrome (SIDS) at under 16 weeks of age were examined immunohistologically and compared to those from 8 age- matched control infants who died from other causes.

RESULTS

The SIDS babies had increased inflammatory changes in the laryngeal epithelium and sub- epithelium with raised numbers of cells staining for elastase (p<0.01), EG2(a marker for activated eosinophils) (p<0.01) and CD4(p<0.05) suggesting that some SIDS deaths involve preceding inflammation.

CONCLUSIONS

Although death may be sudden and unexpected it appears that, at least in some SIDS victims, there is a preceding inflammatory process in the larynx which may allow hyper-reactivity of laryngeal reflexes and consequent apnoea. This observation concurs with others in the SIDS literature and offers a field for further research and possible prevention.

Attenuation of cigarette smoke-induced airway mucus production by hydrogen-rich saline in rats

BACKGROUND

Over-production of mucus is an important pathophysiological feature in chronic airway disease such as chronic obstructive pulmonary disease (COPD) and asthma. Cigarette smoking (CS) is the leading cause of COPD. Oxidative stress plays a key role in CS-induced airway abnormal mucus production. Hydrogen protected cells and tissues against oxidative damage by scavenging hydroxyl radicals. In the present study we investigated the effect of hydrogen on CS-induced mucus production in rats.

METHODS

Male Sprague-Dawley rats were divided into four groups: sham control, CS group, hydrogen-rich saline pretreatment group and hydrogen-rich saline control group. Lung morphology and tissue biochemical changes were determined by immunohistochemistry, Alcian Blue/periodic acid-Schiff staining, TUNEL, western blot and realtime RT-PCR.

RESULTS

Hydrogen-rich saline pretreatment attenuated CS-induced mucus accumulation in the bronchiolar lumen, goblet cell hyperplasia, muc5ac over-expression and abnormal cell apoptosis in the airway epithelium as well as malondialdehyde increase in the BALF. The phosphorylation of EGFR at Tyr1068 and Nrf2 up-regulation expression in the rat lungs challenged by CS exposure were also abrogated by hydrogen-rich saline.

CONCLUSION

Hydrogen-rich saline pretreatment ameliorated CS-induced airway mucus production and airway epithelium damage in rats. The protective role of hydrogen on CS-exposed rat lungs was achieved at least partly by its free radical scavenging ability. This is the first report to demonstrate that intraperitoneal administration of hydrogen-rich saline protected rat airways against CS damage and it could be promising in treating abnormal airway mucus production in COPD.

Effects of a tumor necrosis factor-α antagonist on experimentally induced rhinosinusitis

This prospective, randomized, and controlled study examined the effects of tumor necrosis factor soluble receptor type I (sTNFRI, a TNF-α antagonist) on experimentally induced rhinosinusitis in rats. The experimental groups received an instillation of lipopolysaccharide (LPS) plus an intramuscular injection of amoxicillin/clavulanate (antibiotic group), an instillation of sTNFRI (sTNFRI group), an instillation of sTNFRI and an injection of amoxicillin/clavulanate (sTNFRI/antibiotic group), or no additional treatment (LPS group). Histopathological changes were determined using hematoxylin-eosin and periodic acid-Schiff (PAS) staining. Leakage of exudate was determined using fluorescence microscopy. Vascular permeability was measured using the Evans blue dye technique. Expression of MUC5AC was measured using reverse transcriptase PCR. The sTNFRI, antibiotic, and sTNFRI/antibiotic groups had significantly less capillary permeability, mucosal edema, PAS staining, and expression of MUC5AC than the LPS group. There were no differences in capillary permeability, mucosal edema, PAS staining, and MUC5AC expression between the sTNFRI and sTNFRI/antibiotic groups. The antibiotic group had PAS staining similar to that of the sTNFRI and sTNFRI/antibiotic groups but had a greater increase in capillary permeability, mucosal edema, and MUC5AC expression. This study shows that sTNFRI reduces inflammatory activity and mucus hypersecretion in LPS-induced rhinosinusitis in rats.

Enhanced susceptibility of nasal polyp tissues to avian and human influenza viruses

BACKGROUND

Influenza viruses bind and infect respiratory epithelial cells through sialic acid on cell surface. Differential preference to sialic acid types contributes to host- and tissue-tropism of avian and seasonal influenza viruses. Although the highly pathogenic avian influenza virus H5N1 can infect and cause severe diseases in humans, it is not efficient in infecting human upper respiratory tract. This is because of the scarcity of its receptor, α2,3-linked sialic acid, in human upper airway. Expression of sialic acid can be influenced by various factors including inflammatory process. Allergic rhinitis and nasal polyp are common inflammatory conditions of nasal mucosa and may affect expression of the sialic acid and susceptibility to influenza infection.

METHODOLOGY/PRINCIPAL FINDING

To test this hypothesis, we detected α2,3- and α2,6-linked sialic acid in human nasal polyp and normal nasal mucosal tissues by lectin staining and infected explants of those tissues with avian influenza viruses H5N1 and seasonal influenza viruses. We show here that mucosal surface of nasal polyp expressed higher level of α2,3- and α2,6-linked sialic acid than normal nasal mucosa. Accordingly, both H5N1 avian influenza viruses and seasonal influenza viruses replicated more efficiently in nasal polyp tissues explants.

CONCLUSIONS/SIGNIFICANCE

Our data suggest a role of nasal inflammatory conditions in susceptibility to influenza infection, especially by avian influenza viruses, which is generally inefficient in infecting human upper airway. The increased receptor expression may contribute to increased susceptibility in some individuals. This may contribute to the gradual adaptation of the virus to human population.

Glycoconjugate expression in perennial allergic rhinitis: a lectin histopathological study

CONCLUSIONS

The data show that differences in the concentrations of glycoconjugates of patients with perennial allergic rhinitis (PAR) and normal controls are modest, thus indicating that the composition of the mucus in allergic patients largely resembles that of healthy individuals. The findings may point to the need for volume reduction methods controlling mucus production in patients with PAR.

OBJECTIVES

We aimed to study the composition and concentration of inferior turbinate glycoconjugates of patients with PAR.

MATERIALS AND METHODS

Six specific oligosaccharides found in the inferior turbinate mucosa were stained with a battery of 10 lectins. The samples recruited for study were 15 sections from patients with PAR and 17 from healthy individuals who had no nasal disease and underwent rhinoplasty surgery for cosmetic reasons. Both groups were matched for age (p = 0.208). Results. No significant difference in the concentration of galactose, fucose, sialic acid, N-acetylglucosamine, and N-acetylgalactosamine in the epithelium and submucosal glands of the inferior turbinate was found between the groups. Likewise, neuraminidase digestion of peripheral sialic acid revealed similar concentration of the penultimate galactose residue. The only significant difference was a higher concentration of mannose in submucosal serous glands of patients with PAR compared with normal controls (p = 0.04).

Regulation of mucin expression: mechanistic aspects and implications for cancer and inflammatory diseases

Mucins are large multifunctional glycoproteins whose primary functions are to protect and lubricate the surfaces of epithelial tissues lining ducts and lumens within the human body. Several lines of evidence also support the involvement of mucins in more complex biological processes such as epithelial cell renewal and differentiation, cell signaling, and cell adhesion. Recent studies have uncovered the role of select mucins in the pathogenesis of cancer, underscoring the importance of a detailed knowledge about mucin biology. Under normal physiological conditions, the production of mucins is optimally maintained by a host of elaborate and coordinated regulatory mechanisms, thereby affording a well-defined pattern of tissue-, time-, and developmental state-specific distribution. However, mucin homeostasis may be disrupted by the action of environmental and/or intrinsic factors that affect cellular integrity. This results in an altered cell behavior that often culminates into a variety of pathological conditions. Deregulated mucin production has indeed been associated with numerous types of cancers and inflammatory disorders. It is, therefore, crucial to comprehend the underlying basis of molecular mechanisms controlling mucin production in order to design and implement adequate therapeutic strategies for combating these diseases. Herein, we discuss some physiologically relevant regulatory aspects of mucin production, with a particular emphasis on aberrations that pertain to pathological situations. Our views of the achievements, the conceptual and technical limitations, as well as the future challenges associated with studies of mucin regulation are exposed.

A mechanism of antigen-induced goblet cell degranulation in the nasal epithelium of sensitized rats

BACKGROUND

We have produced hypertrophic and metaplastic changes of goblet cells in nasal epithelium of ovalbumin (OVA)-sensitized rats by intranasal challenge with OVA. A variety of allergic mediators and inflammatory cells are capable of stimulating goblet cell degranulation (epithelial mucus secretion); however, little is known about the mechanism by which antigen induces mucus hypersecretion.

OBJECTIVE

Our aim was to explain the mechanism of goblet cell degranulation in allergic inflammation.

METHODS

Antigen-induced goblet cell degranulation was evaluated by the transient decrease of epithelial mucosubstance 1 to 6 hours after intranasal challenge with OVA in nasal epithelium of OVA-sensitized rats. The effects of the H(1)-antagonist (d -chlorpheniramine malate), H(2)-antagonist (cimetidine), atropine, indomethacin, cysteinyl leukotriene (cysLT) antagonist (ONO1078), and antirat PMN antiserum on OVA-induced goblet cell degranulation were examined.

RESULTS

Goblet cell secretion 1 hour after OVA challenge was significantly inhibited by H(1)-antagonist, atropine, and cysLT antagonist, whereas the secretion 6 hours after the challenge was significantly inhibited by cysLT antagonist and antirat PMN antiserum. Circulating PMN cells and mucosal infiltrating eosinophils were completely abolished by antirat PMN antiserum.

CONCLUSIONS

These results indicate the different mechanisms of goblet cell secretion between early-phase (1 hour after OVA challenge) and late-phase (6 hours after the challenge) reactions. Histamine stimulates early-phase secretion through the H(1)-receptor of cholinergic nerve terminals, and infiltrating inflammatory cells (eosinophils and/or neutrophils) play a role in late-phase secretion. CysLTs (leukotrienes C(4), D(4), and E(4)) are important for both early-phase and late-phase secretion.

LPS up-regulates mucin and cytokine mRNA expression and stimulates mucin and cytokine secretion in goblet cells

Bacterial inflammation in mucosa is accompanied by morphological and proliferative changes in goblet cells and mucin hypersecretion. Main stimulators of bacterial inflammation are bacterial lipopolysaccharides (LPS). In vitro investigation of the LPS effect on the molecular processes in goblet cells, using the human mucin-secreting goblet cell line HT29-MTX, showed the following results. LPS up-regulated mucin and cytokine mRNA expression and secretion in goblet cells in a concentration and time-dependent manner, with a maximum output at an LPS concentration of 100 ng/ml. LPS (100 ng/ml) increased mRNA expression of MUC5AC (2.4x), MUC5B (2.1x), and IL-8 (2.3x) and stimulated secretion of mucins (MUC5AC up to 39%, MUC5B up to 31%) and the inflammatory cytokine IL-8 (up to 10x). A significant correlation was found between the LPS-induced IL-8 secretion and secretion of mucins. These results suggest: (1) goblet cells, responding to the direct stimulation of bacterial LPS by two inflammatory-related processes such as production and secretion of the gel-forming mucins and the inflammatory cytokine IL-8, can be considered as an important part of mucosal immunity and (2) LPS- induced goblet cell mucin secretion can occur partly via IL-8-dependent pathway.