Human Mucosa Research Articles

Emissions from modern engines induce distinct effects in human olfactory mucosa cells, depending on fuel and aftertreatment

Ultrafine particles (UFP) with a diameter of ≤0.1 μm, are contributors to ambient air pollution and derived mainly from traffic emissions, yet their health effects remain poorly characterized. The olfactory mucosa (OM) is located at the rooftop of the nasal cavity and directly exposed to both the environment and the brain. Mounting evidence suggests that pollutant particles affect the brain through the olfactory tract, however, the exact cellular mechanisms of how the OM responds to air pollutants remain poorly known. Here we show that the responses of primary human OM cells are altered upon exposure to UFPs and that different fuels and engines elicit different adverse effects. We used UFPs collected from exhausts of a heavy-duty-engine run with renewable diesel (A0) and fossil diesel (A20), and from a modern diesel vehicle run with renewable diesel (Euro6) and compared their health effects on the OM cells by assessing cellular processes on the functional and transcriptomic levels. Quantification revealed all samples as UFPs with the majority of particles being ≤0.1 μm by an aerodynamic diameter. Exposure to A0 and A20 induced substantial alterations in processes associated with inflammatory response, xenobiotic metabolism, olfactory signaling, and epithelial integrity. Euro6 caused only negligible changes, demonstrating the efficacy of aftertreatment devices. Furthermore, when compared to A20, A0 elicited less pronounced effects on OM cells, suggesting renewable diesel induces less adverse effects in OM cells. Prior studies and these results suggest that PAHs may disturb the inflammatory process and xenobiotic metabolism in the OM and that UFPs might mediate harmful effects on the brain through the olfactory route. This study provides important information on the adverse effects of UFPs in a human-based in vitro model, therefore providing new insight to form the basis for mitigation and preventive actions against the possible toxicological impairments caused by UFP exposure.

P14-01: Emissions from modern engines induce distinct effects in human olfactory mucosa cells, depending on fuel and aftertreatment

P14-01: Emissions from modern engines induce distinct effects in human olfactory mucosa cells, depending on fuel and aftertreatment

P17-31: Acute exposure to urban air ultrafine and coarse particles alters cellular response to SARS-CoV-2 infection in human olfactory mucosa cells from individuals with Alzheimer's disease

P17-31: Acute exposure to urban air ultrafine and coarse particles alters cellular response to SARS-CoV-2 infection in human olfactory mucosa cells from individuals with Alzheimer's disease

Determination of Mucoadhesion of Polyvinyl Alcohol Films to Human Intestinal Tissue.

The absorption of drugs with narrow absorption windows in the upper small intestine can be improved with a mucoadhesive drug delivery system such as enteric films. To predict the mucoadhesive behaviour in vivo, suitable in vitro or ex vivo methods can be performed. In this study, the influence of tissue storage and sampling site on the mucoadhesion of polyvinyl alcohol film to human small intestinal mucosa was investigated. Tissue from twelve human subjects was used to determine adhesion using a tensile strength method. Thawing of tissue frozen at -20 °C resulted in a significantly higher work of adhesion (p = 0.0005) when a low contact force was applied for one minute, whereas the maximum detachment force was not affected. When the contact force and time were increased, no differences were found for thawed tissue compared to fresh tissue. No change in adhesion was observed depending on the sampling location. Initial results from a comparison of adhesion to porcine and human mucosa suggest that the tissues are equivalent.

The orphan MRGPRF receptor is expressed in entero-endocrine cells of the human gut mucosa.

In the past years, it has become clear that the family of Mas-related G protein-coupled receptors plays a central role in neuro-immune communication at mucosal barrier surfaces, in particular in the skin. Remarkably, MRGPR expression at other mucosal surfaces remains poorly characterized. To fill this gap in our understanding, the present study was undertaken to screen and verify the expression of the human MRGPR family members in the mucosal biopsies of the human gastrointestinal (GI) tract. Our findings revealed that, of all human MRGPRs family members, only MRGPRF mRNA is expressed at detectable levels in human mucosal biopsies of both terminal ileum and sigmoid colon. Furthermore, immunohistochemical stainings revealed that MRGPRF is specifically expressed by mucosal entero-endocrine cells (EECs). Overall, this study showed for the first time that the human ileum and colonic mucosa represent a novel expression site for the orphan MRGPRF, more specifically in EECs.

Comparable Response Following Exposure to Biodiesel and Diesel Exhaust Particles in Advanced Multicellular Human Lung Models.

Biodiesel is considered to be a sustainable alternative for fossil fuels such as petroleum-based diesel. However, we still lack knowledge about the impact of biodiesel emissions on humans, as airways and lungs are the primary target organs of inhaled toxicants. This study investigated the effect of exhaust particles from well-characterized rapeseed methyl ester (RME) biodiesel exhaust particles (BDEP) and petro-diesel exhaust particles (DEP) on primary bronchial epithelial cells (PBEC) and macrophages (MQ). The advanced multicellular physiologically relevant bronchial mucosa models were developed using human primary bronchial epithelial cells (PBEC) cultured at air-liquid interface (ALI) in the presence or absence of THP-1 cell-derived macrophages (MQ). The experimental set-up used for BDEP and DEP exposures (18 µg/cm2 and 36 µg/cm2) as well as the corresponding control exposures were PBEC-ALI, MQ-ALI, and PBEC co-cultured with MQ (PBEC-ALI/MQ). Following exposure to both BDEP and DEP, reactive oxygen species as well as the stress protein heat shock protein 60 were upregulated in PBEC-ALI and MQ-ALI. Expression of both pro-inflammatory (M1: CD86) and repair (M2: CD206) macrophage polarization markers was increased in MQ-ALI after both BDEP and DEP exposures. Phagocytosis activity of MQ and the phagocytosis receptors CD35 and CD64 were downregulated, whereas CD36 was upregulated in MQ-ALI. Increased transcript and secreted protein levels of CXCL8, as well as IL-6 and TNF-α, were detected following both BDEP and DEP exposure at both doses in PBEC-ALI. Furthermore, the cyclooxygenase-2 (COX-2) pathway, COX-2-mediated histone phosphorylation and DNA damage were all increased in PBEC-ALI following exposure to both doses of BDEP and DEP. Valdecoxib, a COX-2 inhibitor, reduced the level of prostaglandin E2, histone phosphorylation, and DNA damage in PBEC-ALI following exposure to both concentrations of BDEP and DEP. Using physiologically relevant multicellular human lung mucosa models with human primary bronchial epithelial cells and macrophages, we found BDEP and DEP to induce comparable levels of oxidative stress, inflammatory response, and impairment of phagocytosis. The use of a renewable carbon-neutral biodiesel fuel does not appear to be more favorable than conventional petroleum-based alternative, as regards of its potential for adverse health effects.

Proteomic analysis of the esophageal epithelium reveals key features of eosinophilic esophagitis pathophysiology.

Eosinophilic esophagitis (EoE) is a chronic non-IgE-mediated allergic disease of the esophagus. An unbiased proteomics approach was performed to investigate pathophysiological changes in esophageal epithelium. Additionally, an RNAseq-based transcriptomic analysis in paired samples was also carried out. Total proteins were purified from esophageal endoscopic biopsies in a cohort of adult EoE patients (n = 25) and healthy esophagus controls (n = 10). Differentially accumulated (DA) proteins in EoE patients compared to control tissues were characterized to identify altered biological processes and signaling pathways. Results were also compared with a quantitative proteome dataset of the human esophageal mucosa. Next, results were contrasted with those obtained after RNAseq analysis in paired samples. Finally, we matched up protein expression with two EoE-specific mRNA panels (EDP and Eso-EoE panel). A total of 1667 proteins were identified, of which 363 were DA in EoE. RNA sequencing in paired samples identified 1993 differentially expressed (DE) genes. Total RNA and protein levels positively correlated, especially in DE mRNA-proteins pairs. Pathway analysis of these proteins in EoE showed alterations in immune and inflammatory responses for the upregulated proteins, and in epithelial differentiation, cornification and keratinization in those downregulated. Interestingly, a set of DA proteins, including eosinophil-related and secreted proteins, were not detected at the mRNA level. Protein expression positively correlated with EDP and Eso-EoE, and corresponded with the most abundant proteins of the human esophageal proteome. We unraveled for the first time key proteomic features involved in EoE pathogenesis. An integrative analysis of transcriptomic and proteomic datasets provides a deeper insight than transcriptomic alone into understanding complex disease mechanisms.

COVID infection in 4 steps: Thermodynamic considerations reveal how viral mucosal diffusion, target receptor affinity and furin cleavage act in concert to drive the nature and degree of infection in human COVID-19 disease

We have developed a mechanistic model of SARS-CoV-2 and SARS-CoV infection, exploring the relationship between the viral diffusion in the mucosa and viral affinity for the angiotensin converting enzyme 2 (ACE2) target. Utilising the structural similarity of SARS-CoV and SARS-CoV-2 and a shared viral target receptor (ACE2), but a dramatic difference in upper or lower respiratory tract infectivity, we were able to generate insights into the linkage of mucosal diffusion and target receptor affinity in determining the pathophysiological pathways of these two viruses.Our analysis reveals that for SARS-CoV-2 the higher affinity of ACE2 binding, the faster and more complete the mucosal diffusion in its transport from the upper airway to the region of the ACE2 target on the epithelium. This diffusional process is essential for the presentation of this virus to the furin catalysed highly efficient entry and infection process in the upper respiratory tract epithelial cells. A failure of SARS-CoV to follow this path is associated with lower respiratory tract infection and decreased infectivity. Thus, our analysis supports the view that through tropism SARS-CoV-2 has evolved a highly efficient membrane entry process that can act in concert with a high binding affinity of this virus and its variants for its ACE2 which in turn promotes enhanced movement of the virus from airway to epithelium. In this way ongoing mutations yielding higher affinities of SARS-CoV-2 for the ACE2 target becomes the basis for higher upper respiratory tract infectivity and greater viral spread. It is concluded that SARS-CoV-2 is constrained in the extent of its activities by the fundamental laws of physics and thermodynamics. Laws that describe diffusion and molecular binding. Moreover it can be speculated that the very earliest contact of this virus with the human mucosa defines the pathogenesis of this infection.

Crosstalk between the gut microbiota and innate lymphoid cells in intestinal mucosal immunity.

The human gastrointestinal mucosa is colonized by thousands of microorganisms, which participate in a variety of physiological functions. Intestinal dysbiosis is closely associated with the pathogenesis of several human diseases. Innate lymphoid cells (ILCs), which include NK cells, ILC1s, ILC2s, ILC3s and LTi cells, are a type of innate immune cells. They are enriched in the mucosal tissues of the body, and have recently received extensive attention. The gut microbiota and its metabolites play important roles in various intestinal mucosal diseases, such as inflammatory bowel disease (IBD), allergic disease, and cancer. Therefore, studies on ILCs and their interaction with the gut microbiota have great clinical significance owing to their potential for identifying pharmacotherapy targets for multiple related diseases. This review expounds on the progress in research on ILCs differentiation and development, the biological functions of the intestinal microbiota, and its interaction with ILCs in disease conditions in order to provide novel ideas for disease treatment in the future.

Mucosal CCL28 Chemokine Improves Protection against Genital Herpes through Mobilization of Antiviral Effector Memory CCR10+CD44+ CD62L-CD8+ T Cells and Memory CCR10+B220+CD27+ B Cells into the Infected Vaginal Mucosa.

Four major mucosal-associated chemokines, CCL25, CCL28, CXCL14, and CXCL17, play an important role in protecting mucosal surfaces from infectious pathogens. However, their role in protection against genital herpes remains to be fully explored. The CCL28 is a chemoattractant for the CCR10 receptor-expressing immune cells and is produced homeostatically in the human vaginal mucosa (VM). In this study, we investigated the role of the CCL28/CCR10 chemokine axis in mobilizing protective antiviral B and T cell subsets into the VM site of herpes infection. We report a significant increase in the frequencies of HSV-specific memory CCR10+CD44+CD8+ T cells, expressing high levels of CCR10, in herpes-infected asymptomatic (ASYMP) women compared with symptomatic women. Similarly, a significant increase in the CCL28 chemokine (a ligand of CCR10), was detected in the VM of herpes-infected ASYMP C57BL/6 mice, associated with the mobilization of high frequencies of HSV-specific effector memory CCR10+CD44+CD62L-CD8+ TEM cells and memory CCR10+B220+CD27+ B cells in the VM of HSV-infected ASYMP mice. Inversely, compared with wild-type C57BL/6 mice, the CCL28 knockout (CCL28-/-) mice (1) appeared to be more susceptible to intravaginal infection and reinfection with HSV type 2, and (2) exhibited a significant decrease in the frequencies of HSV-specific effector memory CCR10+CD44+CD62L-CD8+ TEM cells and of memory CD27+B220+ B cells in the infected VM. These findings suggest a critical role of the CCL28/CCR10 chemokine axis in the mobilization of antiviral memory B and T cells within the VM to protect against genital herpes infection and disease.

Complete Genome Sequences of 37 Bacteria from the Human Vaginal Tract.

Microorganisms colonizing the human vaginal mucosa are associated with healthy states, as well as conditions such as bacterial vaginosis and infection-associated preterm birth. Here, we report complete genome sequences of 37 bacterial isolates from the human vaginal tract.

Radiation Impacts Microbiota Compositions That Activate Transforming Growth Factor-Beta Expression in the Small Intestine

The composition of the gut microbiota represents an early indicator of chronic post-radiation outcomes in elderly bone and gastrointestinal homeostasis. Fecal microbiota analyses revealed that the relative abundances of Bacteroides massiliensis, Muribaculum sp., or Prevotella denticola were different between conventional microbiota (CM) and anti-inflammatory restricted microbiota (RM). The murine RM was found conditional on mucosa-associated dysbiosis under both, disturbances of interleukin (IL)-17 signaling and exposure to radiation alone. This review discusses the hypothesis that intestinal microbiota induced alterations in DNA repair and expressed transforming growth factor (TGF)-β in the small intestine, thereby impacting bone microstructure and osteoblast dysfunction in silicon ion (1.5 Gy 28Si ions of 850 MeV/u) irradiated mice. Bacterial microbiota compositions influenced therapeutic approaches, correlated with clinical outcomes in radiotherapy and were associated with alterations of the immune response to severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infections during the last global pandemics. In the absence of TGF-β, functional metagenomics, cytokine profiles, bacterial community analyses in human and murine mucosa cells, and inflammatory markers in rat intestines were analyzed. This research finally showed radiation-induced osteolytic damage to correlated with specific features of intestinal bacterial composition, and these relationships were expatiated together with radiation effects on normal tissue cell proliferation.

A topical rectal douche product containing Q-Griffithsin does not disrupt the epithelial border or alter CD4+ cell distribution in the human rectal mucosa

To reduce HIV transmission, locally applied pre-exposure prophylaxis (PrEP) products for anorectal use will be important complements to oral and injectable PrEP products already available. It is critical to preserve an intact rectal epithelium and avoid an influx of mucosal HIV target cells with such product use. In this phase 1 clinical trial, we evaluated application of a topical rectal douche product containing Q-Griffithsin (Q-GRFT). Colorectal tissue samples were obtained via sigmoidoscopy at baseline, 1 and 24 h after single-dose exposure in 15 healthy volunteers. In situ staining for epithelial junction markers and CD4+ cells were assessed as an exploratory endpoint. A high-throughput, digitalized in situ imaging analysis workflow was developed to visualize and quantify these HIV susceptibility markers. We observed no significant differences in epithelial distribution of E-cadherin, desmocollin-2, occludin, claudin-1, or zonula occludens-1 when comparing the three timepoints or Q-GRFT versus placebo. There were also no differences in %CD4+ cells within the epithelium or lamina propria in any of these comparisons. In conclusion, the rectal epithelium and CD4+ cell distribution remained unchanged following topical application of Q-GRFT. In situ visualization of HIV susceptibility markers at mucosal sites could be useful to complement standard product safety assessments.

Viscoelastic behavior of oral mucosa. A rheological study using small-amplitude oscillatory shear tests

The purpose of this work was to determine the viscoelastic behavior of porcine and human oral mucosa under physiological conditions of temperature, hydration and chewing. The linear elastic and viscous shear moduli of these soft tissues were determined by small-amplitude oscillatory shear (SAOS) tests at masticatory frequency using a stress-controlled rheometer equipped with an immersion cell on punched biopsies 8 mm in diameter. Non physiological conditions of temperature were also used to access other parameters such as the denaturation temperature of collagen.First, the different parameters such as normal force, frequency and maximal strain were adjusted to obtain reliable data on porcine mucosa. The optimal normal force was 0.1N and the linear viscoelastic limit was found for a strain amplitude of 0.5% for both 0.1 and 1 Hz. The storage moduli of porcine mucosa, ranging from 5 to 16 kPa, were in the same range as cutaneous tissues determined by SAOS at equivalent frequencies. The storage modulus, superior to the loss modulus G″, indicates a predominant elastic contribution to shear stress in chewing conditions.Second, this protocol evidenced an influence of the anatomic site of the mouth on the viscoelastic behavior of porcine mucosa, mandibular biopsies having higher storage moduli than maxillary biopsies. Temperature scans showed the mechanical manifestation of collagen denaturation in the 60–70 °C range as previous calorimetric analyses. Finally, this mechanical protocol was successfully adapted to characterize human mucosa in an elderly population. It was shown that the elastic modulus is impacted by local inflammation (gingivitis), decreasing significantly from 6 ± 1.4 kPa to 2.5 ± 0.3 kPa.

A Histochemical Comparison of Feulgen and Papanicolaou Stains in Demonstrating Cytotoxic and Genotoxic Effects of Cigarette Smoking on Human Buccal Mucosa Cells

Background: Different histochemical stains have been applied to demonstrate the cytotoxic and genotoxic effects of cigarette smoking on cells. Feulgen and Papanicolaou were the most popular stains to demonstrate nuclear abnormalities. The aim of this study was to compare Feulgen and Papanicolaou stains in demonstrating the cytotoxic and genotoxic effects of cigarette smoking on exfoliated oral mucosa cells. Methods: A total of 31 cigarette smokers and 15 non-smokers were included in this case-control study. Using a wooden spatula, two samples were taken from each participant. The samples from the left buccal mucosa were stained with Feulgen and the right mucosa with Papanicolaou. The mean number of micronuclei and the number of cells with pyknosis, karyorrhexis, and karyolysis were determined on Feulgen and Papanicolaou-stained slides. The number of counted cells with pyknosis, karyorrhexis, and karyolysis in 1000 cells/subject was recorded. The mean number of micronuclei was determined by the number of counted micronuclei per 1000 cells per subject. Results: The number of micronuclei was not significantly different between Feulgen and Papanicolaou stained samples (P=0.27). Demonstration of karyolysis (P=0.73) and karyorrhexis (P=0.24) was not significantly different between Feulgen and Papanicolaou staining methods. The Feulgen was significantly more effective in demonstrating pyknosis compared to Papanicolaou (P=0.02). Conclusions: Feulgen and Papanicolaou stains had similar effectiveness in demonstrating DNA alterations (micronucleus) and cellular death features (karyorrhexis and karyolysis). Feulgen was preferable to display pyknosis than Papanicolaou.

Involvement of ω-O-acylceramides and protein-bound ceramides in oral permeability barrier formation

The permeability barrier present in the oral cavity is critical for protection from infection. Although lipids have properties suitable for permeability barrier formation, little is known about their role in oral barrier formation. Here, we show the presence of ω-O-acylceramides (acylceramides) and protein-bound ceramides, which are essential for the formation of permeability barriers in the epidermis, in the oral mucosae (buccal and tongue mucosae), esophagus, and stomach in mice. Conditional knockout of the fatty acid elongase Elovl1, which is involved in the synthesis of ≥C24 ceramides including acylceramides and protein-bound ceramides, in the oral mucosae and esophagus causes increased pigment penetration into the mucosal epithelium of thetongue and enhanced aversive responses to capsaicin-containing water. We find acylceramides in the buccal and gingival mucosae and protein-bound ceramides in the gingival mucosa in humans. These resultsindicate that acylceramides and protein-bound ceramides are important for oral permeability barrier formation.

Uptake of Tropheryma whipplei by Intestinal Epithelia.

Tropheryma whipplei (TW) can cause different pathologies, e.g., Whipple's disease and transient gastroenteritis. The mechanism by which the bacteria pass the intestinal epithelial barrier, and the mechanism of TW-induced gastroenteritis are currently unknown. Using ex vivo disease models comprising human duodenal mucosa exposed to TW in Ussing chambers, various intestinal epithelial cell (IEC) cultures exposed to TW and a macrophage/IEC coculture model served to characterize endocytic uptake mechanisms and barrier function. TW exposed ex vivo to human small intestinal mucosae is capable of autonomously entering IECs, thereby invading the mucosa. Using dominant-negative mutants, TW uptake was shown to be dynamin- and caveolin-dependent but independent of clathrin-mediated endocytosis. Complementary inhibitor experiments suggested a role for the activation of the Ras/Rac1 pathway and actin polymerization. TW-invaded IECs underwent apoptosis, thereby causing an epithelial barrier defect, and were subsequently subject to phagocytosis by macrophages. TW enters epithelia via an actin-, dynamin-, caveolin-, and Ras-Rac1-dependent endocytosis mechanism and consecutively causes IEC apoptosis primarily in IECs invaded by multiple TW bacteria. This results in a barrier leak. Moreover, we propose that TW-packed IECs can be subject to phagocytic uptake by macrophages, thereby opening a potential entry point of TW into intestinal macrophages.

The Cultivation Modality and Barrier Maturity Modulate the Toxicity of Industrial Zinc Oxide and Titanium Dioxide Nanoparticles on Nasal, Buccal, Bronchial, and Alveolar Mucosa Cell-Derived Barrier Models.

As common industrial by-products, airborne engineered nanomaterials are considered important environmental toxins to monitor due to their potential health risks to humans and animals. The main uptake routes of airborne nanoparticles are nasal and/or oral inhalation, which are known to enable the transfer of nanomaterials into the bloodstream resulting in the rapid distribution throughout the human body. Consequently, mucosal barriers present in the nose, buccal, and lung have been identified and intensively studied as the key tissue barrier to nanoparticle translocation. Despite decades of research, surprisingly little is known about the differences among various mucosa tissue types to tolerate nanoparticle exposures. One limitation in comparing nanotoxicological data sets can be linked to a lack of harmonization and standardization of cell-based assays, where (a) different cultivation conditions such as an air-liquid interface or submerged cultures, (b) varying barrier maturity, and (c) diverse media substitutes have been used. The current comparative nanotoxicological study, therefore, aims at analyzing the toxic effects of nanomaterials on four human mucosa barrier models including nasal (RPMI2650), buccal (TR146), alveolar (A549), and bronchial (Calu-3) mucosal cell lines to better understand the modulating effects of tissue maturity, cultivation conditions, and tissue type using standard transwell cultivations at liquid-liquid and air-liquid interfaces. Overall, cell size, confluency, tight junction localization, and cell viability as well as barrier formation using 50% and 100% confluency was monitored using trans-epithelial-electrical resistance (TEER) measurements and resazurin-based Presto Blue assays of immature (e.g., 5 days) and mature (e.g., 22 days) cultures in the presence and absence of corticosteroids such as hydrocortisone. Results of our study show that cellular viability in response to increasing nanoparticle exposure scenarios is highly compound and cell-type specific (TR146 6 ± 0.7% at 2 mM ZnO (ZnO) vs. ~90% at 2 mM TiO2 (TiO2) for 24 h; Calu3 93.9 ± 4.21% at 2 mM ZnO vs. ~100% at 2 mM TiO2). Nanoparticle-induced cytotoxic effects under air-liquid cultivation conditions declined in RPMI2650, A549, TR146, and Calu-3 cells (~0.7 to ~0.2-fold), with increasing 50 to 100% barrier maturity under the influence of ZnO (2 mM). Cell viability in early and late mucosa barriers where hardly influenced by TiO2 as well as most cell types did not fall below 77% viability when added to Individual ALI cultures. Fully maturated bronchial mucosal cell barrier models cultivated under ALI conditions showed less tolerance to acute ZnO nanoparticle exposures (~50% remaining viability at 2 mM ZnO for 24 h) than the similarly treated but more robust nasal (~74%), buccal (~73%), and alveolar (~82%) cell-based models.

Synthetic microbial communities (SynComs) of the human gut: design, assembly, and applications.

The human gut harbors native microbial communities, forming a highly complex ecosystem. Synthetic microbial communities (SynComs) of the human gut are an assembly of microorganisms isolated from human mucosa or fecal samples. In recent decades, the ever-expanding culturing capacity and affordable sequencing, together with advanced computational modeling, started a ''golden age'' for harnessing the beneficial potential of SynComs to fight gastrointestinal disorders, such as infections and chronic inflammatory bowel diseases. As simplified and completely defined microbiota, SynComs offer a promising reductionist approach to understanding the multispecies and multikingdom interactions in the microbe-host-immune axis. However, there are still many challenges to overcome before we can precisely construct SynComs of designed function and efficacy that allow the translation of scientific findings to patients' treatments. Here, we discussed the strategies used to design, assemble, and test a SynCom, and address the significant challenges, which are of microbiological, engineering, and translational nature, that stand in the way of using SynComs as live bacterial therapeutics.

The Role of Coagulase-Negative Staphylococci Biofilms on Late-Onset Sepsis: Current Challenges and Emerging Diagnostics and Therapies

Infections are one of the most significant complications of neonates, especially those born preterm, with sepsis as one of the principal causes of mortality. Coagulase-negative staphylococci (CoNS), a group of staphylococcal species that naturally inhabit healthy human skin and mucosa, are the most common cause of late-onset sepsis, especially in preterms. One of the risk factors for the development of CoNS infections is the presence of implanted biomedical devices, which are frequently used for medications and/or nutrient delivery, as they serve as a scaffold for biofilm formation. The major concerns related to CoNS infections have to do with the increasing resistance to multiple antibiotics observed among this bacterial group and biofilm cells' increased tolerance to antibiotics. As such, the treatment of CoNS biofilm-associated infections with antibiotics is increasingly challenging and considering that antibiotics remain the primary form of treatment, this issue will likely persist in upcoming years. For that reason, the development of innovative and efficient therapeutic measures is of utmost importance. This narrative review assesses the current challenges and emerging diagnostic tools and therapies for the treatment of CoNS biofilm-associated infections, with a special focus on late-onset sepsis.