Insights into the Chemistry, Structure, and Biological Activity of Human Salivary MUC7 Fragments and Their Cu(II) and Zn(II) Complexes.

Mucin 7 (MUC7) is one of the salivary proteins whose role in the innate immune system is widely known, but still, neither its mechanism of action nor the impact of its metal coordination is fully understood. MUC7 and its fragments demonstrate potent antimicrobial activity, serving as a natural defense mechanism for organisms against pathogens. This study delves into the bioinorganic chemistry of MUC7 fragments (L1─EGRERDHELRHRRHHHQSPK; L2─EGRERDHELRHRR; L3─HHHQSPK) and their complexes with Cu(II) and Zn(II) ions. The antimicrobial characteristics of the investigated peptides and their complexes were systematically assessed against bacterial and fungal strains at pH 5.40 and pH 7.40. Our findings highlight the efficacy of these systems against Streptococcus sanguinis, a common oral cavity pathogen. Most interestingly, Zn(II) coordination increased (or triggered) the MUC7 antimicrobial activity, which underscores the pivotal role of metal ion coordination in governing the antimicrobial activity of human salivary MUC7 fragments against S. sanguinis.

Rhubarb extract rebuilding the mucus homeostasis and regulating mucin-associated flora to relieve constipation.

In clinical trials, rhubarb extract (Rb) was demonstrated to efficiently alleviate constipation. We would like to find out the underlying mechanism of rhubarb relieving constipation. However, there are few studies on the effects of rhubarb on colonic mucus secretion and constipation. The aim of this study was to investigate the effects of rhubarb on colonic mucus secretion and its underlying mechanism. The mice were randomly divided into four groups. Group I was the control group and Group II was the rhubarb control group, with Rb (24 g/kg body weight [b.w.]) administered through intragastric administration for three days. Group III mice were given diphenoxylate (20 mg/kg b.w.) for five days via gavage to induce constipation. Group IV received diphenoxylate lasting five days before undergoing Rb administration for three days. The condition of the colon was evaluated using an endoscope. Particularly, the diameter of blood vessels in the colonic mucosa expanded considerably in constipation mice along with diminishing mucus output, which was in line with the observation via scanning electron microscope (SEM) and transmission electron microscope (TEM). We also performed metagenomic analysis to reveal the microbiome related to mucin gene expression level referring to mucin secretion. In conclusion, Rb relieves constipation by rebuilding mucus homeostasis and regulating the microbiome.

The effect of zinc oxide (ZnO) nanoparticle concentration on the adhesion of mucin and Streptococcus mutans to heat-cured acrylic resin.

Incorporating zinc oxide (ZnO) nanoparticles as antibacterial fillers in heat-cured acrylic resin could decrease mucin and Streptococcus mutans (S. mutans) adhesion, reducing the incidence of dental caries in the baseplates of orthodontic patients. Here, ZnO nanoparticles were modified using 3-(trimethoxysilyl)propyl methacrylate with various concentrations, added to acrylic resin powder, homogenized, mixed with acrylic resin liquid, and processed. The composite systems interfered well with mucin and S. mutans adhesion. The lowest mean of the amount of mucin adhered was on heat-cured acrylic resin with 7.5% ZnO nanoparticles, with a standard deviation of 18.07±0.80 mg/mL. The ZnO nanoparticles with a concentration of 7.5% showed an 87.09±0.88% S. mutans adhesion in control groups with no additives. These composite systems were proven to have better physicochemical characteristics and antibacterial abilities. Combining ZnO nanoparticles with heat-cured acrylic resin has great potential for self-cleaning baseplates of orthodontic patients in the future.

Nanocrystalline Cellulose Modulates Dysregulated Intestinal Barriers in Ulcerative Colitis.

Ulcerative colitis (UC) is a recurrent chronic inflammation of the colon with increasing incidence and prevalence, which could increase the risk of colorectal cancer. It is urgent to find an effective method with few side effects. Nanocrystalline cellulose (NCC), which is from plant fibers, has a good biocompatibility and high biosafety. Herein, we used NCC to treat UC and evaluated its treatment effect by the disease activity index, intestinal pathology, inflammatory cytokines, tight junction proteins, and mucins. We studied the impact of NCC on mucin expression and gut microbiota to discuss the therapeutic mechanism. NCC can effectively treat UC by regulating the MAPK pathway of mucin 2 and the relative abundance of Akkermansia and Odoribacter, which could not cause the body damage. NCC could not cause body damage compared to the medications, while it had a better effect on the regulation of MUC2 compared to the present drug substitutes. NCC is a practical alternative for the treatment of UC.

In vivo and In silico evidence of the protective properties of carvacrol against experimentally-induced gastric ulcer: Implication of antioxidant, anti-inflammatory, and antiapoptotic mechanisms.

Gastric ulcer is a serious disease that affects millions of individuals worldwide. Alcohol consumption is a major contributor to the disease pathogenesis and ethanol-induced ulcer in rats closely recapitulates the clinical pathology of ulcer. In this study, rats were pretreated with carvacrol (CAR,50 and 100 mg/kg, orally) 1 h before absolute ethanol administration to induce gastric ulcer. CAR prevented ethanol-induced increases in gastric volume and acidity while restored mucin content. The gastro-protective activity of CAR, particularly the higher dose (100 mg/kg), was further supported by histopathological examination, as manifested by reduced gastric lesions. Interestingly, oxidative stress is linked to early stages of ulcer development and progression. In this study, ethanol administration upregulated the levels of ROS-producing enzymes, NADPH oxidase homologs 1 and 4 (Nox1 and Nox4) and lipid peroxides while depleting the antioxidant defense mechanisms, including GSH, Glutathione Peroxidase (GPX) and catalase. Interestingly, these alterations were significantly ameliorated by CAR pretreatment. Additionally, CAR possesses anti-inflammatory and anti-apoptotic activities. Pretreatment with CAR blunted ethanol-induced increases in inflammatory cytokines (NF-κB and TNF-α) and rectified the apoptosis regulator (Bax/Bcl2 ratio) in gastric tissue. Moreover, the docking simulation of CAR illustrated good fitting and interactions with GPX, Nox1 and TNF-α through the formation of hydrogen and hydrophobic (pi-H) bonds with conservative amino acids, thus, further supporting the anti-inflammatory and antioxidant effects underlying the gastroprotective effects of CAR. In conclusion, this study elucidates, using in silico and in vivo models, that the gastroprotective activity of CAR is attributed, at least in part, to its mucin-secretagogue, antioxidative, anti-inflammatory, and anti-apoptotic mechanisms.

Development of an In Vitro Model of the Gut Microbiota Enriched in Mucus-Adhering Bacteria.

Culturing the gut microbiota in in vitro models that mimic the intestinal environment is increasingly becoming a promising alternative approach to study microbial dynamics and the effect of perturbations on the gut community. Since the mucus-associated microbial populations in the human intestine differ in composition and functions from their luminal counterpart, we attempted to reproduce in vitro the microbial consortia adhering to mucus using an already established three-dimensional model of the human gut microbiota. Electrospun gelatin structures supplemented or not with mucins were inoculated with fecal samples and compared for their ability to support microbial adhesion and growth over time, as well as to shape the composition of the colonizing communities. Both scaffolds allowed the establishment of long-term stable biofilms with comparable total bacterial loads and biodiversity. However, mucin-coated structures harbored microbial consortia especially enriched in Akkermansia, Lactobacillus, and Faecalibacterium, being therefore able to select for microorganisms commonly considered mucosa-associated in vivo. IMPORTANCE These findings highlight the importance of mucins in shaping intestinal microbial communities, even those in artificial gut microbiota systems. We propose our in vitro model based on mucin-coated electrospun gelatin structures as a valid device for studies evaluating the effects of exogenous factors (nutrients, probiotics, infectious agents, and drugs) on mucus-adhering microbial communities.

Transmembrane Mucin Response in Conjunctival Epithelial Cells Exposed to Wall Shear Stresses.

Human conjunctival epithelium cells (HCEC) line the inner surface of the eyelid and cover the sclera and are continuously subjected to wall shear stresses (WSS). The effects of external forces on the conjunctival epithelium are not fully known. The conjunctival epithelium contains stratified squamous cells that synthesize the membrane-spanning mucins MUC1 and MUC16, which play important roles in protecting the ocular surface. Alterations in both gel-forming and membrane-tethered mucins occur in drying ocular surface diseases. The aim of this study was to explore the mechanobiological characteristics of transmembrane mucin secretion and cellular alterations of primary HCEC exposed to airflow-induced WSS perturbations. We exposed the HCEC to a steady WSS of 0.5 dyne/cm2 for durations of 15 and 30 min. Cytoskeletal alterations and MUC1 secretions were studied using immunohistochemically fluorescent staining with specific antibodies. We investigated for the first time an in vitro model of membrane-tethered mucin secretion by HCEC in response to WSS. The exposure of HCEC to WSS increased the polymerization of F-actin, altered the cytoskeletal shape and reduced the secretion of membrane-tethered MUC1.

Acquired resistance to EGFR-TKIs in NSCLC mediates epigenetic downregulation of MUC17 by facilitating NF-κB activity via UHRF1/DNMT1 complex.

Treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has brought significant benefits to non-small cell lung cancer (NSCLC) patients with EGFR mutations. However, most patients eventually develop acquired resistance after treatment. This study investigated the epigenetic effects of mucin 17 (MUC17) in acquired drug-resistant cells of EGFR-TKIs. We found that GR/OR (gefitinib/osimertinib-resistance) cells enhance genome-wide DNA hypermethylation, mainly in 5-UTR associated with multiple oncogenic pathways, in which GR/OR cells exerted a pro-oncogenic effect by downregulating mucin 17 (MUC17) expression in a dose- and time-dependent manner. Gefitinib/osimertinib acquired resistance mediated down-regulation of MUC17 by promoting DNMT1/UHRF1 complex-dependent promoter methylation, thereby activating NF-κB activity. MUC17 increased the generation of IκB-α and inhibit NF-κB activity by promoting the expression of MZF1. In vivo results also showed that DNMT1 inhibitor (5-Aza) in combination with gefitinib/osimertinib restored sensitivity to OR/GR cells. Acquired drug resistance of gefitinib/osimertinib promoted UHRF1/DNMT1 complex to inhibit the expression of MUC17. MUC17 in GR/OR cells may act as an epigenetic sensor for biomonitoring the resistance to EGFR-TKIs.

Mucus Penetration of Surface-Engineered Nanoparticles in Various pH Microenvironments.

The penetration behavior of nanoparticles in mucous depends on physicochemical properties of the nanoparticles and the mucus microenvironment, due to particle-mucin interactions and the presence of the mucin mesh space filtration effect. To date, it is still unclear how the surface properties of nanoparticles influence their mucus penetration behaviors in various physiological and pathophysiological conditions. In this study, we have prepared a comprehensive library of amine-, carboxyl-, and PEG-modified silica nanoparticles (SNPs) with controlled surface ligand densities. Using multiple particle tracking, we have studied the mechanism responsible for the mucus penetration behaviors of these SNPs. It was found that PEG- and amine-modified SNPs exhibited pH-independent immobilization under iso-density conditions, while carboxyl-modified SNPs exhibited enhanced movement only in weakly alkaline mucus. Biophysical characterizations demonstrated that amine- and carboxyl-modified SNPs were trapped in mucus due to electrostatic interactions and hydrogen bonding with mucin. In contrast, high-density PEGylated surface formed a brush conformation that shields particle-mucin interactions. We have further investigated the surface property-dependent mucus penetration behavior using a murine airway distribution model. This study provides insights for designing efficient transmucosal nanocarriers for prevention and treatment of pulmonary diseases.

Effect of epithelial-specific MyD88 signaling pathway on airway inflammatory response to organic dust exposure.

The Toll-like receptor (TLR) adaptor protein MyD88 is integral to airway inflammatory response to microbial-enriched organic dust extract (ODE) exposures. ODE-induced airway neutrophil influx and release of pro-inflammatory cytokines was essentially abrogated in global MyD88-deficient mice, yet these mice demonstrate an increase in airway epithelial cell mucin expression. To further elucidate the role of MyD88-dependent responses specific to lung airway epithelial cells in response to ODE in vivo, the surfactant protein C protein (SPC) Cre+ embryologic expressing airway epithelial cells floxed for MyD88 to disrupt MyD88 signaling were utilized. The inducible club cell secretory protein (CCSP) Cre+, MyD88 floxed, were also developed. Using an established protocol, mice were intranasally instilled with ODE or saline once or daily up to 3 weeks. Mice with MyD88-deficient SPC+ lung epithelial cells exhibited decreased neutrophil influx following ODE exposure once and repetitively for 1 week without modulation of classic pro-inflammatory mediators including tumor necrosis factor (TNF)-α, interleukin (IL)-6, and neutrophil chemoattractants. This protective response was lost after 3 weeks of repetitive exposure. ODE-induced Muc5ac mucin expression at 1 week was also reduced in MyD88-deficient SPC+ cells. Acute ODE-induced IL-33 was reduced in MyD88-deficient SPC+ cells whereas serum IgE levels were increased at one week. In contrast, mice with inducible MyD88-deficient CCSP+ airway epithelial cells demonstrated no significant difference in experimental indices following ODE exposure. Collectively, these findings suggest that MyD88-dependent signaling targeted to all airway epithelial cells plays an important role in mediating neutrophil influx and mucin production in response to acute organic dust exposures.

Multifunctional glycoprotein coatings improve the surface properties of highly oxygen permeable contact lenses.

To achieve and maintain good operability of medical devices while reducing putative side effects for the patient, a promising strategy is to tailor the surface properties of such devices as they critically dictate the tissue compatibility and the biofouling behavior. Indeed, those properties can be strongly improved by generating mucin coatings on such medical devices. However, using coatings on optical systems, e.g., contact lenses, comes with various challenges: here, the geometrical and optical characteristics of the lens may not be compromised by either the coating process or the coating itself. In this study, we show how mucin macromolecules can be attached onto the surfaces of rigid, gas permeable contact lenses while maintaining all critical lens parameters. We demonstrate that the generated coatings improve the surface wettability (contact angles are reduced from 105° to 40° and liquid film break-up times are increased from <1 s to 31 s) and prevent tribological damage to corneal tissue. Additionally, such coatings are highly transparent (transmission values above 98 % compared to an uncoated sample are reached) and efficiently reduce lipid deposition to the lens surface by 90 % but fully maintain the geometrical and mechanical properties of the lenses. Thus, such mucin coatings could also be highly beneficial for other optical systems that are used in direct contact with tissues or body fluids.

[Improvement effect of Shegan Mahuang Decoction on rats with cold-induced asthma based on TRPV1/NRF-1/mtTFA pathway].

This study investigated the therapeutic effect of Shegan Mahuang Decoction(SGMHD) on cold-induced asthma in rats and explored its underlying mechanism. Seventy-two healthy male SD rats of specific pathogen free(SPF) grade were randomly divided into a blank group, a model group, a positive control group(dexamethasone, 0.4 mg·kg~(-1)), and low-, medium-, and high-dose SGMHD groups(3.2, 6.4, and 12.8 g·kg~(-1)). The blank group received saline, while the other groups were sensitized by intraperitoneal injection of ovalbumin(OVA) solution. Subsequently, the rats were placed in a cold chamber adjustable to 0-2 ℃, and OVA solution was ultrasonically nebulized to induce cold-induced asthma in rats. After three weeks of treatment, the general behaviors of rats were observed. Hematoxylin-eosin(HE) staining was used to evaluate pathological changes in lung tissues, periodic acid-Schiff(PAS) staining assessed mucin changes, and Masson staining was performed to examine collagen deposition. Enzyme-linked immunosorbent assay(ELISA) was used to measure the levels of the inflammatory factors interleukin-4(IL-4) and vascular endothelial growth factor(VEGF) in serum and bronchoalveolar lavage fluid(BALF). Real-time quantitative polymerase chain reaction(RT-PCR) was employed to assess the mRNA expression levels of transient receptor potential vanilloid subfamily member 1(TRPV1), nuclear respiratory factor 1(NRF-1), and mitochondrial transcription factor A(mtTFA) in lung tissues. Western blot was used to measure the protein expression levels of TRPV1, NRF-1, and mtTFA in lung tissues. Compared with the blank group, the model group exhibited signs of rapid respiration, increased frequency of defecation with looser stools, and disheveled and dull fur. Pathological results showed significant infiltration of inflammatory cells in lung tissues, narrowing of bronchial lumens, increased mucin secretion, and enhanced collagen deposition in the model group. Additionally, the levels of IL-4 and VEGF in serum and BALF were significantly elevated, and the mRNA and protein expression levels of TRPV1, NRF-1, and mtTFA in lung tissues were significantly increased. Compared with the model group, SGMHD improved the behaviors of rats, alleviated pathological changes in lung tissues, mucin production, and collagen deposition, significantly decreased the levels of IL-4 and VEGF in serum and BALF, and reduced the mRNA expression levels of TRPV1, NRF-1, and mtTFA in lung tissues, with the medium-dose SGMHD group showing the most significant effect. Moreover, the protein expression levels of TRPV1, NRF-1, and mtTFA in lung tissues were also reduced, with the medium-dose SGMHD group exhibiting the most significant effect. In conclusion, this study demonstrates that SGMHD can alleviate airway inflammation and inhibit airway remodeling in cold-induced asthma rats. These effects may be associated with the modulation of the TRPV1/NRF-1/mtTFA signaling pathway.

Efficacy Comparison of LPA2 Antagonist H2L5186303 and Agonist GRI977143 on Ovalbumin-Induced Allergic Asthma in BALB/c Mice.

Lysophosphatidic acid (LPA), an intercellular lipid mediator, is increased in the bronchoalveolar fluids of patients with asthma after allergen exposure. LPA administration exaggerates allergic responses, and the type 2 LPA receptor (LPA2) has been reported as a therapeutic target for asthma. However, results with LPA2 agonist and antagonist along with LPA2 gene deficient mice have been controversial and contradictory. We compared the effects of LPA2 antagonist (H2L5186303) and agonist (GRI977143) in a single experimental protocol of ovalbumin (OVA)-induced allergic asthma by treating drugs before antigen sensitization or challenge. H2L5186303 showed strong suppressive efficacy when administered before OVA sensitization and challenge, such as suppression of airway hyper responsiveness, inflammatory cytokine levels, mucin production, and eosinophil numbers. However, GRI977143 showed significant suppression when administered before an OVA challenge. Increases in eosinophil and lymphocyte counts in the bronchoalveolar lavage fluid, Th2 cytokine levels, inflammatory scores, and mucin production were differentially ameliorated by the two drugs. The results demonstrate the multiple roles of LPA2 in asthmatic responses. We suggest that the development of LPA2 antagonists would achieve better therapeutic efficacy against asthma than agonists.

Oxysophocarpine inhibits airway inflammation and mucus hypersecretion through JNK/AP-1 pathway in vivo and in vitro.

Asthma is a high-incidence disease in the world. Oxysophocarpine (OSC), a quinolizidine alkaloid displays various pharmacological functions including anti-inflammation, neuroprotective, anti-virus and antioxidant. Here, we established mice and cell asthmatic model to explore the effects of OSC for asthma treatment. Mice were sensitized and challenged with ovalbumin (OVA) and treated with OSC before challenge. Enzyme-linked immuno sorbent assay (ELISA), hematoxylin and eosin (H&E), periodic acid-schiff (PAS), tolonium chloride staining and immunohistochemical assay were performed. OSC treatment inhibited inflammatory cell infiltration and mucus secretion in the airway, reduced IgE level in mouse serum and decreased IL-4, IL-5 production in bronchoalveolar lavage fluid (BALF). OSC also reduced the spleen index to regulate immune function. Meanwhile, NCI-H292 cells were induced by lipopolysaccharide (LPS) to simulate airway epithelial injury. OSC pretreatment decreased the IL-6 and IL-8 cytokine levels, mucin 5 AC expression, and mucin 5 AC mRNA level in the cell model. Further, OSC suppressed the phosphorylation of c-Jun N-terminal kinase (JNK), and activator protein 1 (AP-1, Fos and Jun). These findings revealed that OSC alleviated bronchial asthma associated with JNK/AP-1 signaling pathway.

Activity-based protein profiling identifies alternating activation of enzymes involved in the bifidobacterium shunt pathway or mucin degradation in the gut microbiome response to soluble dietary fiber.

While deprivation of dietary fiber has been associated with adverse health outcomes, investigations concerning the effect of dietary fiber on the gut microbiome have been largely limited to compositional sequence-based analyses or utilize a defined microbiota not native to the host. To extend understanding of the microbiome's functional response to dietary fiber deprivation beyond correlative evidence from sequence-based analyses, approaches capable of measuring functional enzymatic activity are needed. In this study, we use an activity-based protein profiling (ABPP) approach to identify sugar metabolizing and transport proteins in native mouse gut microbiomes that respond with differential activity to the deprivation or supplementation of the soluble dietary fibers inulin and pectin. We found that the microbiome of mice subjected to a high fiber diet high in soluble fiber had increased functional activity of multiple proteins, including glycoside hydrolases, polysaccharide lyases, and sugar transport proteins from diverse taxa. The results point to an increase in activity of the Bifidobacterium shunt metabolic pathway in the microbiome of mice fed high fiber diets. In those subjected to a low fiber diet, we identified a shift from the degradation of dietary fibers to that of gut mucins, in particular by the recently isolated taxon "Musculibacterium intestinale", which experienced dramatic growth in response to fiber deprivation. When combined with metabolomics and shotgun metagenomics analyses, our findings provide a functional investigation of dietary fiber metabolism in the gut microbiome and demonstrates the power of a combined ABPP-multiomics approach for characterizing the response of the gut microbiome to perturbations.

Protein disulfide isomerases (PDIs) negatively regulate ebolavirus structural glycoprotein expression in the endoplasmic reticulum (ER) via the autophagy-lysosomal pathway.

Zaire ebolavirus (EBOV) causes a severe hemorrhagic fever in humans and non-human primates with high morbidity and mortality. EBOV infection is dependent on its structural glycoprotein (GP), but high levels of GP expression also trigger cell rounding, detachment, and downregulation of many surface molecules that is thought to contribute to its high pathogenicity. Thus, EBOV has evolved an RNA editing mechanism to reduce its GP expression and increase its fitness. We now report that the GP expression is also suppressed at the protein level in cells by protein disulfide isomerases (PDIs). Although PDIs promote oxidative protein folding by catalyzing correct disulfide formation in the endoplasmic reticulum (ER), PDIA3/ERp57 adversely triggered the GP misfolding by targeting GP cysteine residues and activated the unfolded protein response (UPR). Abnormally folded GP was targeted by ER-associated protein degradation (ERAD) machinery and, unexpectedly, was degraded via the macroautophagy/autophagy-lysosomal pathway, but not the proteasomal pathway. PDIA3 also decreased the GP expression from other ebolavirus species but increased the GP expression from Marburg virus (MARV), which is consistent with the observation that MARV-GP does not cause cell rounding and detachment, and MARV does not regulate its GP expression via RNA editing during infection. Furthermore, five other PDIs also had a similar inhibitory activity to EBOV-GP. Thus, PDIs negatively regulate ebolavirus glycoprotein expression, which balances the viral life cycle by maximizing their infection but minimizing their cellular effect. We suggest that ebolaviruses hijack the host protein folding and ERAD machinery to increase their fitness via reticulophagy during infection.Abbreviations: 3-MA: 3-methyladenine; 4-PBA: 4-phenylbutyrate; ACTB: ß-actin; ATF: activating transcription factor; ATG: autophagy-related; BafA1: bafilomycin A1; BDBV: Bundibugyo ebolavirus; CALR: calreticulin; CANX: calnexin; CHX: cycloheximide; CMA: chaperone-mediated autophagy; ConA: concanamycin A; CRISPR: clusters of regularly interspaced short palindromic repeats; Cas9: CRISPR-associated protein 9; dsRNA: double-stranded RNA; EBOV: Zaire ebolavirus; EDEM: ER degradation enhancing alpha-mannosidase like protein; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 3; Env: envelope glycoprotein; ER: endoplasmic reticulum; ERAD: ER-associated protein degradation; ERN1/IRE1: endoplasmic reticulum to nucleus signaling 1; GP: glycoprotein; HA: hemagglutinin; HDAC6: histone deacetylase 6; HMM: high-molecular-mass; HIV-1: human immunodeficiency virus type 1; HSPA5/BiP: heat shock protein family A (Hsp70) member 5; IAV: influenza A virus; IP: immunoprecipitation; KIF: kifenesine; Lac: lactacystin; LAMP: lysosomal associated membrane protein; MAN1B1/ERManI: mannosidase alpha class 1B member 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MARV: Marburg virus; MLD: mucin-like domain; NHK/SERPINA1: alpha1-antitrypsin variant null (Hong Kong); NTZ: nitazoxanide; PDI: protein disulfide isomerase; RAVV: Ravn virus; RESTV: Reston ebolavirus; SARS-CoV: severe acute respiratory syndrome coronavirus; SBOV: Sudan ebolavirus; sGP: soluble GP; SQSTM1/p62: sequestosome 1; ssGP: small soluble GP; TAFV: Taï Forest ebolavirus; TIZ: tizoxanide; TGN: thapsigargin; TLD: TXN (thioredoxin)-like domain; Ub: ubiquitin; UPR: unfolded protein response; VLP: virus-like particle; VSV: vesicular stomatitis virus; WB: Western blotting; WT: wild-type; XBP1: X-box binding protein 1.

Targeting MUCL1 protein inhibits cell proliferation and EMT by deregulating ß­catenin and increases irinotecan sensitivity in colorectal cancer.

With >1.85 million cases and 850,000 deaths annually, colorectal cancer (CRC) is the third most common cancer detected globally. CRC is an aggressive malignancy with metastasis and, in spite of advances in improved treatment regimen, distant disease failure rates remain disappointingly high. Mucin­like 1 (MUCL1) is a small glycoprotein highly expressed mainly in breast cancer. The involvement of the MUCL1 protein in CRC progression and the underlying mechanism have been largely unknown. The aim of the present study was to investigate the MUCL1 expression profile and its functional significance in CRC. The Cancer Genome Atlas dataset revealed that MUCL1 expression was higher in colorectal tumor compared with normal tissues. MUCL1 was also revealed to be expressed in human CRC cell lines. The results demonstrated that MUCL1 promoted cell proliferation and colony formation, confirming its oncogenic potential. Silencing MUCL1 with short interfering RNA inhibited the protein expression of Bcl2 family proteins, such as Bcl2 and BclxL. Targeting MUCL1 resulted in significant inhibition in cell invasive and migratory behavior of HT­29 and SW620 cells. In addition, the expression of E­cadherin increased whereas the expression of vimentin decreased in MUCL1­silenced cells, confirming inhibition of epithelial­mesenchymal transition (EMT) process. Thus, it was revealed that MUCL1 plays a notable role in cell invasion and migration by inhibiting EMT in CRC. Mechanistically, MUCL1 drives ß­catenin activation by Ser­552 phosphorylation, nuclear accumulation and transcriptional activation. Targeting MUCL1 increases the drug sensitivity of CRC cells towards irinotecan. These findings thus demonstrated that MUCL1 acts as a modifier of other pathways that play an important role in CRC progression and MUCL1 was identified as a potential target for CRC therapeutics.

Polysaccharide from edible alga Gloiopeltis furcata attenuates intestinal mucosal damage by therapeutically remodeling the interactions between gut microbiota and mucin O-glycans.

Gloiopeltis furcata is an edible alga that has long been consumed in China. However, the bioactive polysaccharides from G. furcata have been largely unexplored. Here, we show for the first time that a sulfated polysaccharide from G. furcata (SAO) could improve the integrity of the colonic epithelial layer and protect against dextran sulfate sodium-induced intestinal mucosal damage. Mechanistically, SAO attenuated colonic mucosal damage by therapeutically remodeling the interactions between gut microbiota and mucin O-glycans. Specifically, SAO increased the proportions of complex long-chain mucin O-glycans in the epithelial layer with two terminal N-acetylneuraminic acid residues and promoted the growth of probiotic bacteria including Roseburia spp. and Muribaculaceae. Altogether, our study demonstrates a novel application of SAO for the treatment of inflammatory bowel disease-associated mucosal damage and forms the basis to understand the therapeutic effects of natural polysaccharides from the perspective of symbiotic interactions between host mucin O-glycome and gut microbiome.

Platycodin D attenuates airway inflammation via suppression Th2 transcription factor in a murine model of acute asthma.

Introduction: Bronchial asthma is a common chronic inflammatory condition of the airway tissue. Platycodin D (PLD) has antiinflammatory effects in a mouse model of allergic asthma. In this work, the anti-asthma potential of PLD was studied by investigation of its effect to suppress airway inflammation and mucin production, a murine model of asthma and the possible mechanisms.Methods: Mice were randomly assigned to five experimental groups: control, ovalbumin (OVA), OVA+ICS (intranasal fluticasone), OVA+PLD and OVA+PLD/ICS. Airway histological studies were evaluated by the H&E staining; IL-4, IL-5, and IL-13 in bronchoalveolar lavage fluid were evaluated by ELISA; GATA3 and IRF4 mRNA of airway were measured by RT-PCR and their protein level were measured by Western blotting.Results: Our study showed that PLD suppressed eosinophilic inflammation and mucin production in bronchial mucosa. Moreover, PLD inhibited production of Th2 cytokines such as IL-4, IL-5, and IL-13. Protein production of GATA3 and IRF4, were also decreased in PLD treated OVA asthma model. Taken together, our results provided evidence that PLD inhibits the airway inflammation via suppression of Th2 transcription factor production.Conclusion: These findings suggest that PLD may effectively ameliorate the progression of asthma. These results suggest that PLD could be used as a therapy for allergic asthma.

Mucin secretory action of capsaicin prevents high fat diet-induced gut barrier dysfunction in C57BL/6 mice colon.

The gut barrier - including tight junction proteins (TJPs) and mucus layers, is the first line of defense against physical, chemical or pathogenic incursions. This barrier is compromised in various health disorders. Capsaicin, a dietary agonist of Transient receptor potential vanilloid 1 (TRPV1) channel, is reported to alleviate the complications of obesity. While it is well known to improve energy expenditure and metabolism, and prevent dysbiosis, the more local effects on the host gut - particularly the gut barrier and mucus system remain elusive. To investigate the effect of capsaicin on the gut barrier and mucus production and to understand the involvement of mucus, bacteria, and TRPV1 in these phenomena, we employed a diet-induced obesity model in C57BL/6 mice, and capsaicin (2 mg/kg/day p.o.) or mucin (1 g/kg/day p.o.) as interventions, for 12 weeks. Parameters like weight gain, glucose homeostasis, TJPs expression, mucus staining, intestinal permeability etc were studied. 16 S rDNA sequencing and in vitro Ca2+ measurement experiments were performed to explore the role of microbiota in the beneficial effects. Mucin feeding reflected several anti-obesity effects produced by capsaicin, suggesting that mucus modulation might play a crucial role in capsaicin-induced anti-obesity effects. 16 S rDNA sequencing and in vitro Ca2+ measurement experiments pointed to TRPV1 modulation by bacteria besides capsaicin. Capsaicin, bacteria and the host mucus system seem to act in a cyclic cascade involving TRPV1, which can be activated by capsaicin and various bacteria. These findings provide new insight into the role of TRPV1 in maintaining a healthy gut environment.