Mucosal Surfaces Research Articles

Acute Respiratory Distress Syndrome Secondary to Rabies: A Case Report and Review of the Literature

Introduction: Introduction: Rabies is a zoonotic viral infection with a worldwide distribution, primarily found in Asia and Africa, leading to an annual mortality rate of approximately 60 000 cases. The rabies virus is an RNA virus primarily transmitted through mucosal surfaces or contact with compromised skin. In this study, we present a case of rabies associated with acute respiratory distress syndrome (ARDS). Case Presentation: A 64-year-old male who had been bitten by a dog three weeks prior to admission presented to our emergency department with restlessness. A lung CT scan revealed nearly complete opacification of both lungs, indicative of ARDS. Unfortunately, the patient passed away within 5 hours of admission. An autopsy was conducted, and brain samples tested positive for rabies using the direct fluorescent antibody technique. Conclusions: ARDS is a rare but fatal extra-neural complication of rabies, potentially linked to cytokine storms and nitric oxide as etiological factors. Nevertheless, further investigations are warranted to gain a more precise understanding of the pathogenesis.

The Conjunctival Microbiome and Dry Eye: What We Know and Controversies.

Dry eye disease is a common multifactorial condition that may be idiopathic or associated with autoimmune conditions, such as Sjogren syndrome. Commensal microorganisms modify immune responses, so it is relevant to understand how they modify such immune-mediated diseases. Microbiota in the gut regulate inflammation in the eye, and conversely, severe inflammation of the ocular surface results in alteration of gut microbiome. The conjunctiva microbiome can be analyzed using 16S or shotgun metagenomics. The amount of microbial DNA in ocular surface mucosa relative to human DNA is limited compared with the case of the intestinal microbiome. There are challenges in defining, harvesting, processing, and analyzing the microbiome in the ocular surface mucosa. Recent studies have shown that the conjunctiva microbiome depends on age, presence of local and systemic inflammation, and environmental factors. Microbiome-based therapy, such as the use of oral probiotics to manage dry eye disease, has initial promising results. Further longitudinal studies are required to investigate the alteration of the conjunctival microbiome after local therapy and surgery.

Investigation of healthy horse eyes microbiota and evaluation of its antimicrobial susceptibility

SummaryBackgroundThe conjunctiva of the eye is a mucosal surface that is colonised by various bacteria. Following surgery, trauma or other underlying conditions the normal flora may cause eye infection such as conjunctival and corneal infections, or endophthalmitis.ObjectivesThis study aimed to investigate the bacterial population and antibiotic resistance of the conjunctiva in healthy horses.Study designRandom sampling of ocular samples from 20 horses during the winter (2019).MethodsSwab samples were collected from the eyes of 20 healthy horses of different breeds, ages and sexes in Tehran province, Iran. The swabs were cultured on blood agar and MacConkey agar and incubated at 37°C for 24–48 h. The isolated bacteria were characterised using cellular morphology, gram‐staining and biochemical tests. Sensitivity and resistance to 10 different antibiotics were measured using an antibiogram test.ResultsResults showed that the bacterial population consisted of various species, with Bacillus cereus being the most frequent. There were no significant differences in the frequency of isolated bacteria between sexes and age groups. There were no significant differences in the sensitivity of the bacterial flora of the eyes to colistin, ceftiofur, florfenicol, amoxicillin and ampicillin between either different age groups or different sexes of the horses (p > 0.05). However, sensitivity to enrofloxacin and ciprofloxacin was significantly correlated with the age groups of the horses (p > 0.05). A significant difference in sensitivity to trimethoprim‐sulfamethoxazole between various sexes of horses was observed.Main limitationsThe nonuniformity of the follow‐up examination, reliance on owners or caregivers of the horse for follow‐up information and lack of adequate financial resources to study more horses.ConclusionsThe study suggests that the frequency of individual bacteria comprising the bacterial flora in horses' eyes is influenced by housing and management conditions rather than age and sex.

Microbiome analyses in chronic rhinosinusitis.

In this edition of Rhinology we feature the work of Connell and colleagues from Australia on chronic rhinosinusitis that describes an interesting new pipeline to characterize the bacterial composition of microbiota. We are constantly exposed to a multitude of micro-organisms in the environment and our immune system has the important task discerning and fighting off potential threats. In most people the immune system is doing its job properly and prevents anything untoward from happening. On occasion, a microbe slips by the first (innate) level of defense and we might suffer from an infection. This then activates the second layer of (the adaptive) defense tasked to clear this infection. Sometimes the immune system gets its wrong and starts a full-out defense against something harmless, and an allergy is born. The task of the immune system of doing what is right is even more difficult than it might seem at first sight. In addition to these incidental potential threats, our mucosal surfaces are lined with commensal bacteria which contributes to the complexity of our environment. This collection of bacteria or microbiome has become a major focus of research, as the composition of this microbiome seems related to the health state of the individual. Originally the relationship between the gut microbiome and the development of asthma and allergy was the main focus. In recent years, the focus has been broadened to include the microbiome of the upper and lower airways. In addition to allergy, our field has also been given more and more attention to studying the microbiome in chronic rhinosinusitis.

Persistent B Cell-Derived MHC Class II Signaling Is Required for the Optimal Maintenance of Tissue-Resident Helper T Cells.

Emerging studies have identified the critical roles of tissue-resident memory CD8+ T (TRM) and B (BRM) cells in the protection against mucosal viral infections, but the underlying mechanisms regulating robust development of TRM and BRM cells remain incompletely understood. We have recently shown that tissue-resident helper CD4+ T (TRH) cells, developed following influenza virus infection, function to sustain the optimal maintenance of TRM and BRM cells at the mucosal surface. In this study, we have explored the cellular and molecular cues modulating lung TRH persistence after influenza infection in C57BL/6 mice. We found that TRH cells were colocalized in tertiary lymphoid structures (TLSs) with local B cells. Abolishing TLSs or the depletion of B cells impaired lung TRH cell numbers. Of note, we found that persistent TCR signaling is needed for the maintenance of TRH cells after the clearance of infectious influenza virus. Furthermore, selective ablation of B cell-derived MHC class II resulted in partial reduction of lung TRH cell number after influenza infection. Our findings suggest that the interaction between lung-resident TRH cells and B cells, along with persistent Ag stimulation, is required to maintain TRH cells after respiratory viral infection.

The avian influenza A virus receptor SA-α2,3-Gal is expressed in the porcine nasal mucosa sustaining the pig as a mixing vessel for new influenza viruses

Influenza A viruses (IAVs) originate from wild birds but have on several occasions jumped host barriers and are now also circulating in humans and mammals. The IAV host receptors (glycans with galactose linked to a sialic acid (SA) in an α2,3 or α2,6 linkage) are crucial host factors restricting inter-species transmission. In general, avian-origin IAVs show a preference for SA-α2,3 (avian receptor), whereas IAVs isolated from humans and pigs prefer SA-α2,6 (human receptor). N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) are the two major SAs. Neu5Ac is expressed in all species, whereas Neu5Gc is only expressed in a limited number of domestic species such as pigs and horses, but not in humans. Despite that previous studies have shown that the IAV host receptor distribution appears to be similar in pigs and humans, none of these studies have investigated the expression of Neu5Gc-α2,6 in situ in porcine tissues. Thus, the aim of this study was to elucidate the distribution of IAV host receptors expressed in the porcine respiratory tract and relate the expression to the viral tropism of diverse host-adapted IAVs.The IAV receptor (SA-α2,3 and SA-α2,6) distribution and the presence of specifically Neu5Gc-α2,6 in the porcine nasal, tracheal, and lung tissues was investigated by lectin histochemistry. Furthermore, IAV immunohistochemistry was performed on tissues from pigs experimentally infected with IAVs, either adapted to pigs or humans, to investigate the significance of the IAV host receptors and the tropism of the diverse host-adapted IAVs. We document for the first time the expression of the avian receptor on the surface of the porcine nasal mucosa and an equal expression of Neu5Ac- α2,6 and Neu5Gc-α2,6 on the surface of the tracheal epithelium and alveoli. In all IAV-infected pigs, we found a low amount of IAV-positive cells in the trachea despite a high expression of the human receptor. Cumulatively, these findings suggest that optimal IAV replication involves a complex interplay between the viruses and their host receptors and that there might be other less clearly defined host factors that determine the site of replication.

Giant major aphtha.

Major aphthae are usually located on the dorsum of the tongue, the mucosal surface of the lips and the palate. They are large, round or oval ulcers, with a whitish-grey bed, well-defined borders and erythematous halo. They are very often accompanied by severe pain. Major aphthae can take up to four months to heal, often with a scar. Relapses are possible. We present a case of giant major aphtha that was previously diagnosed as squamous cell carcinoma.

Gut complement induced by the microbiota combats pathogens and spares commensals

Canonically, the complement system is known for its rapid response to remove microbes in the bloodstream. However, relatively little is known about a functioning complement system on intestinal mucosal surfaces. Herein, we report the local synthesis of complement component 3 (C3) in the gut, primarily by stromal cells. C3 is expressed upon commensal colonization and is regulated by the composition of the microbiota in healthy humans and mice, leading to an individual host's specific luminal C3 levels. The absence of membrane attack complex (MAC) components in the gut ensures that C3 deposition does not result in the lysis of commensals. Pathogen infection triggers the immune system to recruit neutrophils to the infection site for pathogen clearance. Basal C3 levels directly correlate with protection against enteric infection. Our study reveals the gut complement system as an innate immune mechanism acting as a vigilant sentinel that combats pathogens and spares commensals.

NANOPARTICLE ENCAPSULATION OF THE SPECIALIZED PRO-RESOLVING MEDIATOR MARESIN-2: A NOVEL APPROACH FOR PROMOTING MUCOSAL REPAIR IN THE INTESTINE

Abstract Epithelial cells form protective barriers at mucosal surfaces and play a critical role in maintaining tissue homeostasis. Active inflammation in inflammatory bowel disease (IBD) is associated with epithelial barrier disruption and mucosal erosions/wounds that contribute to the inflammatory response and disease symptoms. Therefore, efficient repair of epithelial erosions/wounds is crucial for restoring intestinal barrier function and resolving mucosal inflammation. In response to injury, epithelial cells proliferate and migrate to cover denuded surfaces and restore critical barrier properties. Resident and recruited immune cells at sites of injury release factors that play an important role in orchestrating mucosal repair. Bioactive lipid mediators released by leukocytes, including leukotrienes and specialized pro-resolving mediators (SPMs), regulate epithelial signaling pathways to influence mucosal repair processes. Liquid chromatography-mass spectrometry (LCMS) analyses of healing colonic mucosal wounds performed to detect SPMs identified high levels of MaR2 in healing colonic wounds. In vitro studies using primary colonic epithelial cells revealed MaR2-driven increases in epithelial wound repair that were potentiated by the pro-inflammatory cytokines TNFα and IFNγ. While MaR2 increased epithelial migration by activating cell matrix adhesion proteins, including Src-paxillin and focal adhesion kinase, we did not observe any influence of MaR2 on the activation of cyclin D1/D2 or on epithelial proliferation. Importantly, in vivo studies demonstrated enhanced colonic mucosal wound repair and recovery from dextran sulfate-induced colitis in mice administered MaR2. Given the thermolabile nature of MaR2 (and associated ultracold storage requirements), thermostable polylactic acid (PLA) nanoparticles (NP) containing MaR2 (PLA MaR2) were generated. PLA MaR2 nanoparticles retained bioactivity following extended storage at room temperature and exhibited potent effects on in vivo colonic biopsy induced wound repair. Taken together these data reveal that thermostable MaR2 containing nanoparticles represent a promising new therapeutic approach for regenerating epithelial barrier function and restoring mucosal homeostasis in individuals with IBD.

P1229 The Role and Niche-Specific Adaptation of Malassezia in patients with Ulcerative colitis

Abstract Background Accumulating evidence has underscored the role of gut fungal microbiota (mycobiota) in the development of inflammatory bowel disease. We aimed to isolate a Malassezia strain directly from the human intestine mucosal surface from the patients with ulcerative colitis (UC) and investigated its genome and virulence in comparison with the same fungal species isolated from the human skin. Methods Mucosal lavage samples were collected separately from colonic areas with and without inflammation in patients with UC. Samples from healthy individuals (HT) were obtained in the same manner as from patients with UC at sigmoid or descending colon. Skin samples were taken from HT in our previous work. DNA was extracted from these lavage samples, and fungal isolation was conducted using PCR amplification with ITS4 and ITS5 primers. Comprehensive analysis and comparison of the genomes, transcriptomes, and virulence between M. globosa gut isolates and those of M. globosa strains isolated from the skin were performed. To determine the contribution of M. globosa gut isolates to exacerbating inflammation, 1107 fungal cells were orally gavaged to DSS-induced colitis mouse model for three days. Results Total 56 and 11 intestinal water-lavage samples from 29 UC patients and 11 HT were obtained respectively. The α- and b-diversities of mycobiota showed no significant differences between the groups, patients with UC vs. HT or the sites with inflammation vs. non-inflammation of the patient with UC. Malassezia was the fifth most frequently found fungal genus throughout the samples, and live fungal strains belong to 28 and 7 different species were isolated from the patients with UC and HT, respectively. The patients with UC tend to have higher frequency of M. globosa and M. restricta than HT in their gut mucosal surface with inflammation. Whole genome sequencing showed no specific genomic characteristics between gut-isolated M. globosa and skin-isolated M. globosa. However, gut-isolated M. globosa were suffered more from the higher oxygen levels than the skin isolates in different oxygen concentrations. In a mouse model, gut-isolated M. globosa exhibited a more pronounced exacerbation of DSS-induced colitis and elevated production of inflammatory cytokines, including TNF-a, IL-6, IL-12p40, IL-1b, and IL-18, while the skin isolates showed no difference compared to the negative control (Figure). Conclusion Our data shed new light on the pivotal role of M. globosa in the pathogenesis of UC, highlighting the potential influence of niche-specific adaptations on the virulence of this fungus. These findings provide critical insights into the complex interplay between the member of the gut mycobiota and host health.

P338 The dependence of the level of Glycoprotein type 2 on the level of Zonulin in Crohn's disease

Abstract Background Introduction. Type 2 glycoprotein (GP2) is a quantitatively predominant membrane protein of excretory granules of pancreatic acinar cells. In a number of studies, it has been demonstrated that this protein is the main antigen for pancreatic antibodies associated with Crohn's disease Zonulin – a protein that can reversibly increase the permeability of the intestinal wall by changing the structure of tight junctions of the lateral surfaces of intestinal epithelial cells. The determination of fecal zonulin is used for noninvasive assessment of increased intestinal permeability. Normal values of zonulin in stool (≤ 110 ng/ml) indicate the absence of damage to the villous surface of the intestinal mucosa and normal density of intercellular contacts The aim of the study was to establish the dependence of the level of type 2 glycoprotein on the level of fecal zonulin (FZ) in the feces of CD patients with exacerbation of the disease. Methods 122 patients with CD in the form of ilekolitis with exacerbation of the disease (Me age — 32 years) were examined. FZ was evaluated by ELISA (IDK ® Zonulin ELISA Kit, Immunodiagnostik AG, Germany) in ng/ml. Reference values: < 83.15 ng/ml is a variant of the norm, 83.15-110 ng/ml is an elevated level, 110 ng/ml is a high level. The level of IgG and IgA to GP2 (antibodies to glycoprotein) antigen of pancreatic centroacinar cells (Anti-GP2, IgG, IgA) was determined by ELISA. Reference values: IgG GP-2 less than 10 units/ml, Ig and GP-2 less than 5 units/ml – positive values. Results In the stool samples of CD patients during the period of exacerbation in 92 patients, an increase in FZ was detected, the average value was 333.4 ±16.9 ng/ml. In the blood samples of 87 patients with CD during the period of exacerbation, an increase in Ig A GP-2 was detected, the average value was 43.4±6.9 units/ml. In the blood samples of 107 CD patients during the period of exacerbation, an increase in Ig G GP-2 was detected, the average value was 17.1 ± 1.3 units/ml. There is a high correlation force between the concentration of FZ and the concentration of Ig A GP-2 (r-0.760) (p=0.010). There is a moderate correlation force (r-0.490) (p=0.023) between the concentration of FZ and the concentration of Ig G GP-2. Conclusion An increase in the concentration of FZ in the feces of CD patients during exacerbation significantly correlates with an increase in the concentration of Ig A GP-2 and Ig G GP-2.

The Hazards of Probiotics on Gut-Derived Pseudomonas aeruginosa Sepsis in Mice Undergoing Chemotherapy.

Pseudomonas aeruginosa (P. aeruginosa) is a leading cause of nosocomial infections associated with a high mortality rate and represents a serious threat to human health and the increasing frequency of antimicrobial resistance. Cancer patients are more vulnerable to invasive infection due to ulcerative lesions in mucosal surfaces and immune suppression secondary to chemotherapy. In our in vitro study, we observed that probiotics have the potential to yield beneficial effects on intestinal epithelial cells infected with P. aeruginosa. Additionally, probiotics were found to confer advantageous effects on the innate immunity of mice suffering from Salmonella-induced colitis. As a result, we sought to investigate the impact of probiotics on gut-derived P. aeruginosa sepsis induced by chemotherapy. Following chemotherapy, gut-derived P. aeruginosa sepsis was induced in female C57BL/6 mice aged 6-8 weeks, which were raised under specific-pathogen-free (SPF) conditions in an animal center. Prior to the induction of the sepsis model, the mice were administered 1 × 108 colony-forming units (CFU) of the probiotics, namely Lactobacillus rhamnosus GG (LGG) and Bifidobacterium longum (BL) via oral gavage. We observed that LGG or BL amplified the inflammatory mRNA expression in mice undergoing chemotherapy and suffering from gut-derived P. aeruginosa sepsis. This led to a heightened severity of colitis, as indicated by histological examination. Meanwhile, there was a notable decrease in the expression of antimicrobial peptide mRNA along with reduced levels of zonulin and claudin-2 protein staining within mucosal tissue. These alterations facilitated the translocation of bacteria to the liver, spleen, and bloodstream. To our astonishment, the introduction of probiotics exacerbated gut-derived P. aeruginosa sepsis in mice undergoing chemotherapy. Conclusively, we must be prudent when using probiotics in mice receiving chemotherapy complicated with gut-derived P. aeruginosa sepsis.

Oral Health-Related Quality of Life among Complete Denture Stomatitis Patients Treated with Methylene-Blue-Mediated Photodynamic Therapy

Aim: The aim was to assess the effect of antimicrobial photodynamic therapy (a-PDT) on the oral health-related quality of life (OHRQoL) of denture stomatitis patients. Methods: Forty patients were randomly selected to participate. Candidal proliferation was confirmed by using a CHROMagar culture and Gram staining. The denture surface and palatal mucosa were sprayed with a methylene blue photosensitizer prior to the photobiomodulation application. Laser therapy was applied two times a week at 72 h intervals for a period of 8 weeks. The OHIP-EDENT questionnaire was used to analyze the improvement in the OHRQoL. A Wilcoxon test was used to perform the candidal colony-forming unit’s count and comparison. A t-test was applied to evaluate the OHRQoL responses. Results: The overall CFU/mL values were higher in the dentures of the patients compared to a palatal mucosa swab. For instance, the CFU count was reduced from 5.56 ± 2.15 (baseline) to 3.17 ± 2.77 CFU/mL on day 60 on the palates. Similarly, the a-PDT application on the intaglio surface of the denture showed a reduction from 38.83 ± 14.71 to 29.05 ± 15.52 CFU/mL. A significant difference (p < 0.05) was found in function improvement as well as a reduction in physical pain, psychological discomfort, physical disability, and social interaction among the participants after photobiomodulation treatment. Conclusions: The OHRQoL was significantly improved in the DS patients. The Candida albicans abundance was radically reduced after the a-PDT application.

Neutrophil-mediated type IV collagen degradation is elevated in patients with mild endoscopic ulcerative colitis reflecting early mucosal destruction

Neutrophils play a significant role in sustaining chronic inflammation in Inflammatory Bowel Disease. The intestinal basement membrane acts as a barrier for immunological homeostasis, where the α3 and α4 chains of type IV collagen are expressed on the mucosal surface. We wanted to develop a biomarker reflecting early tissue injury, providing an opportunity for intervention. Two competitive enzyme-linked immunosorbent assays (ELISAs) quantifying human neutrophil elastase (HNE) degraded neo-epitopes of COL4A3 and COL4A4 were developed and investigated in two observational cohorts (n = 161, n = 100). A biomarker of MMP-mediated degradation of COL4A1 (C4M) was used for comparison. In Cohort 1, patients with mild endoscopic ulcerative colitis showed elevated levels of C4A3-HNE compared to those with severe disease. C4M had a strong positive correlation with disease activity. C4A3-HNE/C4M provided superior discrimination between mild and severe endoscopic disease and negatively correlated to disease activity. In Cohort 2, C4A4-HNE and C4A4-HNE/C4M showed similar trends. C4A3-HNE and C4A4-HNE possibly reflect early intestinal tissue injury. Combining the markers with a biomarker of another α-chain of the same collagen provides information on two distinct stages of mucosal damage. These biomarkers may be used to monitor disease flare-up in patients in remission, reducing the need for frequent endoscopic procedures.

Evaluating Kaposi Sarcoma in Kidney Transplant Patients: A Systematic Review and Meta-Analysis.

Kaposi's sarcoma (KS) is a malignancy that commonly appears as lesions on the skin or mucosal surfaces but can also develop in other organs. This cancer is usually caused by the human herpesvirus 8 (HHV-8), recently known as Kaposi's sarcoma-associated herpesvirus (KSHV). KS is rare in the general population but can develop in kidney transplant recipients with varying incidence due to immunocompromised status from immunosuppression. The main aim of the present systematic review was to identify the prevalence and treatment of KS in kidney transplant patients. PubMed, Cochrane Library, and Google Scholar databases were searched for studies until October 2023. Full-text studies with similar research objectives were included, while non-English articles, reviews, case reports, ongoing clinical trials, and studies evaluating KS in HIV patients or after other solid organ transplants were excluded. All studies were observational; therefore, methodological quality was assessed using the Newcastle-Ottawa Scale. The statistical analyses were performed with the Comprehensive Meta-Analysis (CMA) software (Biostat, Inc.Englewood, NJ). The pooled analysis from the 15 studies includedshowed that KS develops in 1.5% of kidney transplant recipients and is more prevalent in African (1.7%) and Middle Eastern (1.7%) recipients than in Western recipients (0.07%). KS was also significantly more prevalent among male recipients than female recipients (OR: 2.36; p < 0.0001). Additionally, cyclosporine-based immunosuppression accounts for most KS incidences (79.6%) compared to azathioprine-based immunosuppression (28.2%). Furthermore, reduction or withdrawal of immunosuppression alone resulted in 47.8% KS complete remissions. Post-kidney transplantation KS is more frequent among males and patients of Middle Eastern and African origin. However, the gender difference may be attributed to most patients undergoing kidney transplants being male. Therefore, if gender balance is considered in future studies, then the difference might be insignificant. Based on our results, we can concur that the mainstay treatment for post-transplant KS is reduction or withdrawal of immunosuppression. However, the patients should be closely monitored to avoid KS recurrence and kidney rejection. Furthermore, there is an increased risk for KS with the use of cyclosporine-based immunosuppression. However, this does not mean that the withdrawal of this immunosuppression agent might result in improved KS outcomes because the withdrawal of azathioprine with or without cyclosporine reduction has also led to improved outcomes.

Characterization of MdpS: an in-depth analysis of a MUC5B-degrading protease from Streptococcus oralis.

Oral biofilms, comprising hundreds of bacteria and other microorganisms on oral mucosal and dental surfaces, play a central role in oral health and disease dynamics. Streptococcus oralis, a key constituent of these biofilms, contributes significantly to the formation of which, serving as an early colonizer and microcolony scaffold. The interaction between S. oralis and the orally predominant mucin, MUC5B, is pivotal in biofilm development, yet the mechanism underlying MUC5B degradation remains poorly understood. This study introduces MdpS (Mucin Degrading Protease from Streptococcus oralis), a protease that extensively hydrolyses MUC5B and offers an insight into its evolutionary conservation, physicochemical properties, and substrate- and amino acid specificity. MdpS exhibits high sequence conservation within the species and also explicitly among early biofilm colonizing streptococci. It is a calcium or magnesium dependent serine protease with strict physicochemical preferences, including narrow pH and temperature tolerance, and high sensitivity to increasing concentrations of sodium chloride and reducing agents. Furthermore, MdpS primarily hydrolyzes proteins with O-glycans, but also shows activity toward immunoglobulins IgA1/2 and IgM, suggesting potential immunomodulatory effects. Significantly, MdpS extensively degrades MUC5B in the N- and C-terminal domains, emphasizing its role in mucin degradation, with implications for carbon and nitrogen sequestration for S. oralis or oral biofilm cross-feeding. Moreover, depending on substrate glycosylation, the amino acids serine, threonine or cysteine triggers the enzymatic action. Understanding the interplay between S. oralis and MUC5B, facilitated by MdpS, has significant implications for the management of a healthy eubiotic oral microenvironment, offering potential targets for interventions aimed at modulating oral biofilm composition and succession. Additionally, since MdpS does not rely on O-glycan removal prior to extensive peptide backbone hydrolysis, the MdpS data challenges the current model of MUC5B degradation. These findings emphasize the necessity for further research in this field.

Surface Cross-Linking by Macromolecular Tethers Enhances Virus-like Particles' Resilience to Mucosal Stress Factors.

Virus-like particles (VLPs) are emerging as nanoscaffolds in a variety of biomedical applications including delivery of vaccine antigens and cargo such as mRNA to mucosal surfaces. These soft, colloidal, and proteinaceous structures (capsids) are nevertheless susceptible to mucosal environmental stress factors. We cross-linked multiple capsid surface amino acid residues using homobifunctional polyethylene glycol tethers to improve the persistence and survival of the capsid to model mucosal stressors. Surface cross-linking enhanced the stability of VLPs assembled from Acinetobacter phage AP205 coat proteins in low pH (down to pH 4.0) and high protease concentration conditions (namely, in pig and mouse gastric fluids). Additionally, it increased the stiffness of VLPs under local mechanical indentation applied using an atomic force microscopy cantilever tip. Small angle X-ray scattering revealed an increase in capsid diameter after cross-linking and an increase in capsid shell thickness with the length of the PEG cross-linkers. Moreover, surface cross-linking had no effect on the VLPs' mucus translocation and accumulation on the epithelium of in vitro 3D human nasal epithelial tissues with mucociliary clearance. Finally, it did not compromise VLPs' function as vaccines in mouse subcutaneous vaccination models. Compared to PEGylation without cross-linking, the stiffness of surface cross-linked VLPs were higher for the same length of the PEG molecule, and also the lifetimes of surface cross-linked VLPs were longer in the gastric fluids. Surface cross-linking using macromolecular tethers, but not simple conjugation of these molecules, thus offers a viable means to enhance the resilience and survival of VLPs for mucosal applications.

Opportunities and challenges with transitioning to non-lethal sampling of wild fish for microbiome research.

The microbial communities of fish are considered an integral part of maintaining the overall health and fitness of their host. Research has shown that resident microbes reside on various mucosal surfaces, such as the gills, skin, and gastrointestinal tract, and play a key role in various host functions, including digestion, immunity, and disease resistance. A second, more transient group of microbes reside in the digesta, or feces, and are primarily influenced by environmental factors such as the host diet. The vast majority of fish microbiome research currently uses lethal sampling to analyse any one of these mucosal and/or digesta microbial communities. The present paper discusses the various opportunities that non-lethal microbiome sampling offers, as well as some inherent challenges, with the ultimate goal of creating a sound argument for future researchers to transition to non-lethal sampling of wild fish in microbiome research. Doing so will reduce animal welfare and population impacts on fish while creating novel opportunities to link host microbial communities to an individual's behavior and survival across space and time (e.g., life-stages, seasons). Current lethal sampling efforts constrain our ability to understand the mechanistic ecological consequences of variation in microbiome communities in the wild. Transitioning to non-lethal sampling will open new frontiers in ecological and microbial research.

Esophageal intramural pseudodiverticulosis.

Esophageal intramural pseudodiverticulosis (EIPD) is a disease of unknown pathogenesis characterized by usually systemic, cystic dilatation of the excretory ducts of esophageal submucosal glands. In this article, I review the epidemiology, clinical manifestations, endoscopic findings, esophagographic findings, and histopathology of EIPD. I also discuss the etiology and possible pathogenesis of EIPD based on my experiences with this disease and a review of the literature. EIPD usually presents with dysphagia in middle-aged individuals. It is often complicated with secondary infections, most commonly candidiasis. On esophagography, EIPD is delineated as small, multiple, flask-shaped outward projections within the esophageal wall. In recent years, EIPD has been mainly diagnosed by endoscopic findings of multiple, localized, small mucosal depressions. The orifices of the "pseudodiverticula" periodically open and close, and excrete mucus onto the mucosal surface. On histopathological examination, the luminal surface of dilated ducts in EIPD is covered by multilayered, hyperplastic epithelial cells, but myoepithelial cells in the glandular acini are well preserved. Treatment of EIPD is usually symptomatic therapy, and prevention of the infectious complications is important. The etiology and pathogenesis of EIPD are largely unknown, but functional abnormalities of autonomic nerve fibers innervating the esophageal glands likely play an important role, since the structures of the glands are basically preserved in this disease.

Ocular mucosal homeostasis of teleost fish provides insight into the coevolution between microbiome and mucosal immunity

BackgroundThe visual organ plays a crucial role in sensing environmental information. However, its mucosal surfaces are constantly exposed to selective pressures from aquatic or airborne pathogens and microbial communities. Although few studies have characterized the conjunctival-associated lymphoid tissue (CALT) in the ocular mucosa (OM) of birds and mammals, little is known regarding the evolutionary origins and functions of immune defense and microbiota homeostasis of the OM in the early vertebrates.ResultsOur study characterized the structure of the OM microbial ecosystem in rainbow trout (Oncorhynchus mykiss) and confirmed for the first time the presence of a diffuse mucosal-associated lymphoid tissue (MALT) in fish OM. Moreover, the microbial communities residing on the ocular mucosal surface contribute to shaping its immune environment. Interestingly, following IHNV infection, we observed robust immune responses, significant tissue damage, and microbial dysbiosis in the trout OM, particularly in the fornix conjunctiva (FC), which is characterized by the increase of pathobionts and a reduction of beneficial taxa in the relative abundance in OM. Critically, we identified a significant correlation between viral-induced immune responses and microbiome homeostasis in the OM, underscoring its key role in mucosal immunity and microbiota homeostasis.ConclusionsOur findings suggest that immune defense and microbiota homeostasis in OM occurred concurrently in early vertebrate species, shedding light on the coevolution between microbiota and mucosal immunity.1WNPLmNTzstteMxSNP_LzTVideo