Epithelial stem cells: turning over new leaves

Sight of Aged Microplastics Adsorbing Heavy Metal Exacerbated Intestinal Injury: A Mechanistic Study of Autophagy-Mediated Toxicity Response

Contaminant-bearing polystyrene microplastics (PSMPs) may exert significantly different toxicity profiles from their contaminant-free counterparts, with the role of PSMPs in promoting contaminant uptake being recognized. However, studies investigating the environmentally relevant exposure and toxic mechanisms of aged PSMPs binding to Cr are limited. Here, we show that loading of chromium (Cr) markedly alters the physicochemical properties and toxicological profiles of aged PSMPs. Specifically, Cr-bearing aged PSMPs induced severe body weight loss, oxidative stress (OS), autophagy, intestinal barrier injury, inflammation-pyroptosis response, and enteropathogen invasion in mice. Mechanistic investigations revealed that PSMPs@Cr exacerbated the OS, resulting in intestinal barrier damage and inflammation-pyroptosis response via overactivated Notch signaling and autophagy/cathepsin B/IL-1β pathway, respectively, which ultimately elevated mortality related to bacterial pathogen infection. In vitro experiments confirmed that autophagy-mediated reactive oxygen species (ROS) overproduction resulted in severe pyroptosis and impaired intestinal stem cells differentiation alongside the overactivation of Notch signaling in PSMPs@Cr-exposed organoids. Overall, our findings provide an insight into autophagy-modulated ROS overproduction within the acidic environment of autophagosomes, accelerating the release of free Cr from PSMPs@Cr and inducing secondary OS, revealing that PSMPs@Cr is a stable hazard material that induces intestinal injury. These findings provided a potential therapeutic target for environmental MPs pollution caused intestinal disease in patients.

Artemisia argyi mitigates doxorubicin-induced cardiotoxicity by inhibiting mitochondrial dysfunction through the IGF-IIR/Drp1/GATA4 signaling pathway

Doxorubicin (DOX) is mostly utilized as a wide range of antitumor anthracycline to treat different cancers. The severe antagonistic impacts of DOX on cardiotoxicity constrain its clinical application. Many mechanisms are involved in cardiac toxicity induced by DOX in the human body. Mitochondria is a central part of fatty acid and glucose metabolism. Thus, impaired mitochondrial metabolism can increase heart failure risk, which can play a vital role in cardiomyocyte mitochondrial dysfunction. This study aimed to assess the possible cardioprotective effect of water-extracted Artemisia argyi (AA) against the side effect of DOX in H9c2 cells and whether these protective effects are mediated through IGF-IIR/Drp1/GATA4 signaling pathways. Although several studies proved that AA extract has benefits for various diseases, its cardiac effects have not yet been identified. The H9c2 cells were exposed to 1 μM to establish a model of cardiac toxicity. The results revealed that water-extracted AA could block the expression of IGF-IIR/calcineurin signaling pathways induced by DOX. Notably, our results also showed that AA treatment markedly attenuated Akt phosphorylation and cleaved caspase 3, and the nuclear translocation markers NFATC3 and p-GATA4. Using actin staining for hypertrophy, we determined that AA can reduce the effect of mitochondrial reactive oxygen species and cell size. These findings suggest that water-extracted AA could be a suitable candidate for preventing DOX-induced cardiac damage.

Morphological aspects of small intestinal mucosal injury and repair after electron irradiation

Morphological evaluation of the small intestine mucosa and apoptosis activity (caspase-3) is necessary to assess the severity of damage to the small intestine. At the same time, proliferative index based on Ki-67 can be used to assess the regenerative potential of the small intestine. Fragments of small intestine of Wistar rats (n=60) of three groups: I) control (n=20); II) experimental group (n=20; local single electron irradiation at a dose of 2 Gy), III) experimental group (n=20; local single electron irradiation at a dose of 8 Gy) were studied by light microscopy using hematoxylin and eosin staining and immunohistochemical reactions with antibodies to Ki-67 and caspase-3. In all samples of the experimental groups, a decrease in all morphometric indices was observed on day 1 with a tendency to recover on day 3. Small intestinal electron irradiation led to disturbances in the histoarchitecture of varying severity, and an increase in cell apoptosis was observed (increased expression of caspase-3 and decrease in Ki-67). In addition, modulation of the PI3K/AKT and MAPK/ERK signaling pathways was detected. The most pronounced destructive changes were observed in the group of 8 Gy single electron irradiation. Local irradiation of the small intestine with electrons at a dose of 2 and 8 Gy results in a decrease in the number of enterocytes, mainly stem cells of the intestinal crypts.

Relationship of Signaling Pathways between RKIP Expression and the Inhibition of EMT-Inducing Transcription Factors SNAIL1/2, TWIST1/2 and ZEB1/2

Untreated primary carcinomas often lead to progression, invasion and metastasis, a process that involves the epithelial-to-mesenchymal transition (EMT). Several transcription factors (TFs) mediate the development of EMT, including SNAIL1/SNAIL2, TWIST1/TWIST2 and ZEB1/ZEB2, which are overexpressed in various carcinomas along with the under expression of the metastasis suppressor Raf Kinase Inhibitor Protein (RKIP). Overexpression of RKIP inhibits EMT and the above associated TFs. We, therefore, hypothesized that there are inhibitory cross-talk signaling pathways between RKIP and these TFs. Accordingly, we analyzed the various properties and biomarkers associated with the epithelial and mesenchymal tissues and the various molecular signaling pathways that trigger the EMT phenotype such as the TGF-β, the RTK and the Wnt pathways. We also presented the various functions and the transcriptional, post-transcriptional and epigenetic regulations for the expression of each of the EMT TFs. Likewise, we describe the transcriptional, post-transcriptional and epigenetic regulations of RKIP expression. Various signaling pathways mediated by RKIP, including the Raf/MEK/ERK pathway, inhibit the TFs associated with EMT and the stabilization of epithelial E-Cadherin expression. The inverse relationship between RKIP and the TF expressions and the cross-talks were further analyzed by bioinformatic analysis. High mRNA levels of RKIP correlated negatively with those of SNAIL1, SNAIL2, TWIST1, TWIST2, ZEB1, and ZEB2 in several but not all carcinomas. However, in these carcinomas, high levels of RKIP were associated with good prognosis, whereas high levels of the above transcription factors were associated with poor prognosis. Based on the inverse relationship between RKIP and EMT TFs, it is postulated that the expression level of RKIP in various carcinomas is clinically relevant as both a prognostic and diagnostic biomarker. In addition, targeting RKIP induction by agonists, gene therapy and immunotherapy will result not only in the inhibition of EMT and metastases in carcinomas, but also in the inhibition of tumor growth and reversal of resistance to various therapeutic strategies. However, such targeting strategies must be better investigated as a result of tumor heterogeneities and inherent resistance and should be better adapted as personalized medicine.

Promotion of hepatocellular carcinoma stemness and progression by abnormal spindle-like microcephaly-associated protein via the Wnt/β-catenin pathway

Background

Cancer stem cells (CSCs) play a crucial role in tumor recurrence and metastasis, which are the primary causes of death in patients with hepatocellular carcinoma (HCC). Currently, no drug effectively blocks the recurrence and metastasis of liver cancer, leading to a poor prognosis for patients. To enhance treatment outcomes, there is an urgent need to investigate the molecular mechanisms behind the recurrence and progression of liver cancer, with the aim of identifying effective therapeutic targets. Targeting HCC stemness can improve the prognosis of patients with HCC. Abnormal spindle-like microcephaly-associated protein (ASPM) plays a pivotal role in regulating neurogenesis and brain size, which is a centrosome protein. ASPM has been implicated in tumorigenesis and tumor progression, but its regulatory role in HCC stemness is not well understood. This study aims to investigate the role of ASPM in liver cancer stemness and elucidate its potential molecular mechanisms.

Methods

Bioinformatics analysis was used to study the expression of ASPM and its clinical significance in HCC. In vitro and in vivo assays were conducted to clarify the impact of ASPM knockdown on HCC cell stemness. The correlation between ASPM and the Wnt/β-catenin pathway was examined through analysis of online databases and in vitro experiments.

Results

The bioinformatics analysis revealed significant upregulation of ASPM was significantly upregulated in HCC samples, with expression correlating with poor prognosis. In vitro experimental data confirmed elevated ASPM expression in HCC cells compared to normal hepatocytes. Knockdown of ASPM suppressed HCC cell growth, clone formation, spheroid formation, migration, invasion, and the expression of CSC markers CD133 and CD44. This also inhibited the activation of the Wnt/β-catenin pathway. Reactivation of this pathway partially reversed the biological changes induced by ASPM knockdown in HCC cells. Additionally, in vivo data demonstrated that ASPM downregulation reduced the size and weight of xenografts in BALB/c mice, along with decreased expression of CSC markers.

Conclusions

These findings suggest that ASPM promotes HCC stemness and progression through the Wnt/β-catenin pathway. Targeting ASPM or the Wnt/β-catenin pathway may be a promising strategy to prevent HCC chemoresistance and recurrence, ultimately improving patient prognosis.

Origins of cancer: ain't it just mature cells misbehaving?

A pervasive view is that undifferentiated stem cells are alone responsible for generating all other cells and are the origins of cancer. However, emerging evidence demonstrates fully differentiated cells are plastic, can be coaxed to proliferate, and also play essential roles in tissue maintenance, regeneration, and tumorigenesis. Here, we review the mechanisms governing how differentiated cells become cancer cells. First, we examine the unique characteristics of differentiated cell division, focusing on why differentiated cells are more susceptible than stem cells to accumulating mutations. Next, we investigate why the evolution of multicellularity in animals likely required plastic differentiated cells that maintain the capacity to return to the cell cycle and required the tumor suppressor p53. Finally, we examine an example of an evolutionarily conserved program for the plasticity of differentiated cells, paligenosis, which helps explain the origins of cancers that arise in adults. Altogether, we highlight new perspectives for understanding the development of cancer and new strategies for preventing carcinogenic cellular transformations from occurring.

Phylogenetic Tracing of Evolutionarily Conserved Zonula Occludens Toxin Reveals a "High Value" Vaccine Candidate Specific for Treating Multi-Strain Pseudomonas aeruginosa Infections

Extensively drug-resistant Pseudomonas aeruginosa infections are emerging as a significant threat associated with adverse patient outcomes. Due to this organism's inherent properties of developing antibiotic resistance, we sought to investigate alternative strategies such as identifying "high value" antigens for immunotherapy-based purposes. Through extensive database mining, we discovered that numerous Gram-negative bacterial (GNB) genomes, many of which are known multidrug-resistant (MDR) pathogens, including P. aeruginosa, horizontally acquired the evolutionarily conserved gene encoding Zonula occludens toxin (Zot) with a substantial degree of homology. The toxin's genomic footprint among so many different GNB stresses its evolutionary importance. By employing in silico techniques such as proteomic-based phylogenetic tracing, in conjunction with comparative structural modeling, we discovered a highly conserved intermembrane associated stretch of 70 amino acids shared among all the GNB strains analyzed. The characterization of our newly identified antigen reveals it to be a "high value" vaccine candidate specific for P. aeruginosa. This newly identified antigen harbors multiple non-overlapping B- and T-cell epitopes exhibiting very high binding affinities and can adopt identical tertiary structures among the least genetically homologous P. aeruginosa strains. Taken together, using proteomic-driven reverse vaccinology techniques, we identified multiple "high value" vaccine candidates capable of eliciting a polarized immune response against all the P. aeruginosa genetic variants tested.

Notch Signaling: An Emerging Paradigm in the Pathogenesis of Reproductive Disorders and Diverse Pathological Conditions

The highly conserved Notch pathway, a pillar of juxtacrine signaling, orchestrates intricate intercellular communication, governing diverse developmental and homeostatic processes through a tightly regulated cascade of proteolytic cleavages. This pathway, culminating in the migration of the Notch intracellular domain (NICD) to the nucleus and the subsequent activation of downstream target genes, exerts a profound influence on a plethora of molecular processes, including cell cycle progression, lineage specification, cell-cell adhesion, and fate determination. Accumulating evidence underscores the pivotal role of Notch dysregulation, encompassing both gain and loss-of-function mutations, in the pathogenesis of numerous human diseases. This review delves deep into the multifaceted roles of Notch signaling in cellular dynamics, encompassing proliferation, differentiation, polarity maintenance, epithelial-mesenchymal transition (EMT), tissue regeneration/remodeling, and its intricate interplay with other signaling pathways. We then focus on the emerging landscape of Notch aberrations in gynecological pathologies predisposing individuals to infertility. By highlighting the exquisite conservation of Notch signaling in Drosophila and its power as a model organism, we pave the way for further dissection of disease mechanisms and potential therapeutic interventions through targeted modulation of this master regulatory pathway.

A water-soluble arabinoxylan from Chinese liquor distillers' grains: Structural characterization and anti-colitic properties

Chinese liquor distillers' grain (CLDG) is a valuable and abundant by-product from traditional Chinese baijiu production, containing a diverse array of bioactive components that have attracted significant interest. Herein, a water-soluble polysaccharide, DGPS-2B, with a weight-average molecular weight of 37.3 kDa, was isolated from the alkali-extract fraction of CLDG. Methylation and NMR analysis identified that the primary constituents of DGPS-2B are arabinoxylans, with an arabinose-to-xylose ratio of 0.66. In an animal model of colitis, DGPS-2B treatment significantly altered the gut microbiota composition by increasing the SCFA-producing bacteria (e.g., Butyricicoccus) and reducing the mucin-degrading bacteria such as Muribaculaceae. This microbial shift resulted in elevated production of butyrate, acetate, and propionate, which subsequently suppressed NF-κB signaling, decreased the levels of IL-1β, IL-6, and TNFα, and potentially inactivated Notch signaling. These multifaceted effects stimulated mucin 2 production, reduced inflammation and apoptosis in the gut epithelium, and ultimately alleviated colitis symptoms. Collectively, this study not only elucidates the purification and characterization of DGPS-2B from CLDG but also illuminates its anti-colitic properties and the underlying molecular mechanisms. These findings underscore the potential of DGPS-2B as a therapeutic intervention for managing inflammatory bowel disease and emphasize CLDG as a promising source for developing value-added products.

Roles of airway and intestinal epithelia in responding to pathogens and maintaining tissue homeostasis

Epithelial cells form a resilient barrier and orchestrate defensive and reparative mechanisms to maintain tissue stability. This review focuses on gut and airway epithelia, which are positioned where the body interfaces with the outside world. We review the many signaling pathways and mechanisms by which epithelial cells at the interface respond to invading pathogens to mount an innate immune response and initiate adaptive immunity and communicate with other cells, including resident microbiota, to heal damaged tissue and maintain homeostasis. We compare and contrast how airway and gut epithelial cells detect pathogens, release antimicrobial effectors, collaborate with macrophages, Tregs and epithelial stem cells to mount an immune response and orchestrate tissue repair. We also describe advanced research models for studying epithelial communication and behaviors during inflammation, tissue injury and disease.

Potential Immunohistochemical Biomarkers for Grading Oral Dysplasia: A Literature Review

Oral cancer is a prevalent global health issue, with significant morbidity and mortality rates. Despite available preventive measures, it remains one of the most common cancers, emphasising the need for improved diagnostic and prognostic tools. This review focuses on oral potentially malignant disorders (OPMDs), precursors to oral cancer, specifically emphasising oral epithelial dysplasia (OED). The World Health Organisation (WHO) provides a three-tier grading system for OED, and recent updates have expanded the criteria to enhance diagnostic precision. In the prognostic evaluation of OED, histological grading is presently regarded as the gold standard; however, its subjectivity and unreliability in anticipating malignant transformation or recurrence pose notable limitations. The primary objective is to investigate whether specific immunohistochemical biomarkers can enhance OED grading assessment according to the WHO classification. Biomarkers exhibit significant potential for comprehensive cancer risk evaluation, early detection, diagnosis, prognosis, and treatment optimisation. Technological advancements, including sequencing and nanotechnology, have expanded detection capabilities. Some analysed biomarkers are most frequently chosen, such as p53, Ki-67, cadherins/catenins, and other proteins used to differentiate OED grades. However, further research is needed to confirm these findings and discover new potential biomarkers for precise dysplasia grading and minimally invasive assessment of the risk of malignant transformation.

Investigating the therapeutic potential of Allium cepa extract in combating pesticide exposure induced ocular damage

The ocular surface is subject to a range of potentially hazardous environmental factors and substances, owing to its anatomical location, sensitivity, and physiological makeup. Xenobiotic stress exerted by chronic pesticide exposure on the cornea is primarily responsible for ocular irritation, excessive tear production (hyper-lacrimation), corneal abrasions and decreased visual acuity. Traditional medicine hails the humble onion (Allium cepa) for its multi-faceted properties including but not limited to anti-microbial, antioxidant, anti-inflammatory and wound healing. However, there is a lacuna regarding its impact on the ocular surface. Thereby, the current study investigated whether topical application of crude extract of Allium cepa aided in mitigating pesticide-induced damage to the ocular surface. The deleterious effects of pesticide exposure and their mitigation through the topical application of herbal extract of Allium cepa were analysed initially through in vitro evaluation on cell lines and then on the ocular surface via various in-vivo and ex-vivo techniques. Pathophysiological alterations to the ocular surface that impacted vision were explored through detailed neurophysiological screening with special emphasis on visual acuity wherein it was observed that the murine group treated with topical application of Allium cepa extract had comparable visual capacity to the non-pesticide exposed group. Additionally, SOD2 was utilized as an oxidative stress marker along with the expression of cellular apoptotic markers such as Bcl-xL to analyse the impact of pesticide exposure and subsequent herbal intervention on oxidative stress-induced corneal damage. The impact on the corneal epithelial progenitor cell population (ABCG2 and TERT positive cells) was also flowcytometrically analysed. Therefore, from our observations, it can be postulated that the topical application of Allium cepa extract might serve as an effective strategy to alleviate pesticide exposure related ocular damage.

PRX1-positive mesenchymal stem cells drive molar morphogenesis

Mammalian teeth, developing inseparable from epithelial-mesenchymal interaction, come in many shapes and the key factors governing tooth morphology deserve to be answered. By merging single-cell RNA sequencing analysis with lineage tracing models, we have unearthed a captivating correlation between the contrasting morphology of mouse molars and the specific presence of PRX1+ cells within M1. These PRX1+ cells assume a profound responsibility in shaping tooth morphology through a remarkable divergence in dental mesenchymal cell proliferation. Deeper into the mechanisms, we have discovered that Wnt5a, bestowed by mesenchymal PRX1+ cells, stimulates mesenchymal cell proliferation while orchestrating molar morphogenesis through WNT signaling pathway. The loss of Wnt5a exhibits a defect phenotype similar to that of siPrx1. Exogenous addition of WNT5A can successfully reverse the inhibited cell proliferation and consequent deviant appearance exhibited in Prx1-deficient tooth germs. These findings bestow compelling evidence of PRX1-positive mesenchymal cells to be potential target in regulating tooth morphology.

Maternal fiber-rich diet promotes early-life intestinal development in offspring through milk-derived extracellular vesicles carrying miR-146a-5p

BACKGROUNDS

The intestinal development in early life is profoundly influenced by multiple biological components of breast milk, in which milk-derived extracellular vesicles (mEVs) contain a large amount of vertically transmitted signal from the mother. However, little is known about how maternal fiber-rich diet regulates offspring intestinal development by influencing the mEVs.

RESULTS

In this study, we found that maternal resistant starch (RS) consumption during late gestation and lactation improved the growth and intestinal health of offspring. The mEVs in breast milk are the primary factor driving these beneficial effects, especially enhancing intestinal cell proliferation and migration. To be specific, administration of mEVs after maternal RS intake enhanced intestinal cell proliferation and migration in vivo (performed in mice model and indicated by intestinal histological observation, EdU assay, and the quantification of cyclin proteins) and in vitro (indicated by CCK8, MTT, EdU, and wound healing experiments). Noteworthily, miR-146a-5p was found to be highly expressed in the mEVs from maternal RS group, which also promotes intestinal cell proliferation in cells and mice models. Mechanically, miR-146a-5p target to silence the expression of ubiquitin ligase 3 gene NEDD4L, thereby inhibiting DVL2 ubiquitination, activating the Wnt pathway, and promoting intestinal development.

CONCLUSION

These findings demonstrated the beneficial role of mEVs in the connection between maternal fiber rich diet and offspring intestinal growth. In addition, we identified a novel miRNA-146a-5p-NEDD4L-β-catenin/Wnt signaling axis in regulating early intestinal development. This work provided a new perspective for studying the influence of maternal diet on offspring development.

Application of Platelet-Rich Plasma as a Stem Cell Treatment - an Attempt to Clarify a Common Public Misconception

In recent years, there has been a significant increase in the practice of regenerative medicine by health practitioners and direct-to-consumer businesses globally. Among different tools of regenerative medicine, platelet-rich plasma (PRP) and stem cell-based therapies have received considerable attention. The use of PRP, in particular, has gained popularity due to its easy access, simple processing techniques, and regenerative potential. However, it is important to address a common misconception amongst the general public equating to PRP and stem cells due to the demonstrated efficacy of PRP in treating musculoskeletal and dermatological disorders. Notably, PRP promotes regeneration by providing growth factors or other paracrine factors only. Therefore, it cannot replenish or replace the lost cells in conditions where a large number of cells are required to regenerate tissues and/or organs. In such cases, cellbased therapies are the preferred option. Additionally, other tools of regenerative medicine, such as bioprinting, organoids, and mechanobiology also rely on stem cells for their success. Hence, healthcare and commercial entities offering direct-to-customer regenerative therapies should not mislead the public by claiming that the application of PRP is a stem cell-based therapy. Furthermore, it is important for regulatory bodies to strictly monitor these profit-driven entities to prevent them from providing unregulated regenerative treatments and services that claim a broad variety of benefits with little proof of efficacy, safety concerns, and obscure scientific justification.

Platelet-Rich Plasma in Dermatology: New Insights on the Cellular Mechanism of Skin Repair and Regeneration

The skin's recognised functions may undergo physiological alterations due to ageing, manifesting as varying degrees of facial wrinkles, diminished tautness, density, and volume. Additionally, these functions can be disrupted (patho)physiologically through various physical and chemical injuries, including surgical trauma, accidents, or chronic conditions like ulcers associated with diabetes mellitus, venous insufficiency, or obesity. Advancements in therapeutic interventions that boost the skin's innate regenerative abilities could significantly enhance patient care protocols. The application of Platelet-Rich Plasma (PRP) is widely recognized for its aesthetic and functional benefits to the skin. Yet, the endorsement of PRP's advantages often borders on the dogmatic, with its efficacy commonly ascribed solely to the activation of fibroblasts by the factors contained within platelet granules. PRP therapy is a cornerstone of regenerative medicine which involves the autologous delivery of conditioned plasma enriched by platelets. This is achieved by centrifugation, removing erythrocytes while retaining platelets and their granules. Despite its widespread use, the precise sequences of cellular activation, the specific cellular players, and the molecular machinery that drive PRP-facilitated healing are still enigmatic. There is still a paucity of definitive and robust studies elucidating these mechanisms. In recent years, telocytes (TCs)-a unique dermal cell population-have shown promising potential for tissue regeneration in various organs, including the dermis. TCs' participation in neo-angiogenesis, akin to that attributed to PRP, and their role in tissue remodelling and repair processes within the interstitia of several organs (including the dermis), offer intriguing insights. Their potential to contribute to, or possibly orchestrate, the skin regeneration process following PRP treatment has elicited considerable interest. Therefore, pursuing a comprehensive understanding of the cellular and molecular mechanisms at work, particularly those involving TCs, their temporal involvement in structural recovery following injury, and the interconnected biological events in skin wound healing and regeneration represents a compelling field of study.

Key Factors in the Complex and Coordinated Network of Skin Keratinization: Their Significance and Involvement in Common Skin Conditions

The epidermis serves many vital roles, including protecting the body from external influences and healing eventual injuries. It is maintained by an incredibly complex and perfectly coordinated keratinization process. In this process, desquamation is essential for the differentiation of epidermal basal progenitor cells into enucleated corneocytes, which subsequently desquamate through programmed death. Numerous factors control keratinocyte differentiation: epidermal growth factor, transforming growth factor-α, keratinocyte growth factor, interleukins IL-1-β and IL-6, elevated vitamin A levels, and changes in Ca2+ concentration. The backbone of the keratinocyte transformation process from mitotically active basal cells into fully differentiated, enucleated corneocytes is the expression of specific proteins and the creation of a Ca2+ and pH gradient at precise locations within the epidermis. Skin keratinization disorders (histologically characterized predominantly by dyskeratosis, parakeratosis, and hyperkeratosis) may be categorized into three groups: defects in the α-helical rod pattern, defects outside the α-helical rod domain, and disorders of keratin-associated proteins. Understanding the process of keratinization is essential for the pathogenesis of many dermatological diseases because improper desquamation and epidermopoiesis/keratinization (due to genetic mutations of factors or due to immune pathological processes) can lead to various conditions (ichthyoses, palmoplantar keratodermas, psoriasis, pityriasis rubra pilaris, epidermolytic hyperkeratosis, and others).

Stem cells in clinical dentistry

BACKGROUND

Stem cells are present in most of the tissues in the craniofacial complex and play a major role in tissue homeostasis and repair. These cells are characterized by their capacity to differentiate into multiple cell types and to self-renew to maintain a stem cell pool throughout the life of the tissue.

TYPES OF STUDIES REVIEWED

The authors discuss original data from experiments and comparative analyses and review articles describing the identification and characterization of stem cells of the oral cavity.

RESULTS

Every oral tissue except enamel, dentin, and cementum contains stem cells for the entire life span. These stem cells self-renew to maintain a pool of cells that can be activated to replace terminally differentiated cells (for example, odontoblasts) or to enable wound healing (for example, dentin bridge in pulp exposures and healing of periodontal tissues after surgery). In addition, dental stem cells can differentiate into functional blood vessels and nerves. Initial clinical trials have shown that transplanting dental pulp stem cells into disinfected necrotic teeth has allowed for the recovery of tooth vitality and vertical and horizontal root growth in immature teeth with incomplete root formation.

PRACTICAL IMPLICATIONS

As a consequence of these groundbreaking discoveries, stem cell banks are now offering services for the cryopreservation of dental stem cells. The future use of stem cell-based therapies in the clinic will depend on the collaboration of clinicians and researchers in projects designed to understand whether these treatments are safe, efficacious, and clinically feasible.

The Roles of WNT Signaling Pathways in Skin Development and Mechanical-Stretch-Induced Skin Regeneration

The WNT signaling pathway plays a critical role in a variety of biological processes, including development, adult tissue homeostasis maintenance, and stem cell regulation. Variations in skin conditions can influence the expression of the WNT signaling pathway. In light of the above, a deeper understanding of the specific mechanisms of the WNT signaling pathway in different physiological and pathological states of the skin holds the potential to significantly advance clinical treatments of skin-related diseases. In this review, we present a comprehensive analysis of the molecular and cellular mechanisms of the WNT signaling pathway in skin development, wound healing, and mechanical stretching. Our review sheds new light on the crucial role of the WNT signaling pathway in the regulation of skin physiology and pathology.

Nucleoporin downregulation modulates progenitor differentiation independent of nuclear pore numbers

Nucleoporins (NUPs) comprise nuclear pore complexes, gateways for nucleocytoplasmic transport. As primary human keratinocytes switch from the progenitor state towards differentiation, most NUPs are strongly downregulated, with NUP93 being the most downregulated NUP in this process. To determine if this NUP downregulation is accompanied by a reduction in nuclear pore numbers, we leveraged Stochastic Optical Reconstruction Microscopy. No significant changes in nuclear pore numbers were detected using three independent NUP antibodies; however, NUP reduction in other subcellular compartments such as the cytoplasm was identified. To investigate how NUP reduction influences keratinocyte differentiation, we knocked down NUP93 in keratinocytes in the progenitor-state culture condition. NUP93 knockdown diminished keratinocytes' clonogenicity and epidermal regenerative capacity, without drastically affecting nuclear pore numbers or permeability. Using transcriptome profiling, we identified that NUP93 knockdown induces differentiation genes related to both mechanical and immune barrier functions, including the activation of known NF-κB target genes. Consistently, keratinocytes with NUP93 knockdown exhibited increased nuclear localization of the NF-κB p65/p50 transcription factors, and increased NF-κB reporter activity. Taken together, these findings highlight the gene regulatory roles contributed by differential NUP expression levels in keratinocyte differentiation, independent of nuclear pore numbers.

Prognostic Biomarkers of Cell Proliferation in Colorectal Cancer (CRC): From Immunohistochemistry to Molecular Biology Techniques

Colorectal cancer (CRC) is one of the most common and severe malignancies worldwide. Recent advances in diagnostic methods allow for more accurate identification and detection of several molecular biomarkers associated with this cancer. Nonetheless, non-invasive and effective prognostic and predictive testing in CRC patients remains challenging. Classical prognostic genetic markers comprise mutations in several genes (e.g., APC, KRAS/BRAF, TGF-β, and TP53). Furthermore, CIN and MSI serve as chromosomal markers, while epigenetic markers include CIMP and many other candidates such as SERP, p14, p16, LINE-1, and RASSF1A. The number of proliferation-related long non-coding RNAs (e.g., SNHG1, SNHG6, MALAT-1, CRNDE) and microRNAs (e.g., miR-20a, miR-21, miR-143, miR-145, miR-181a/b) that could serve as potential CRC markers has also steadily increased in recent years. Among the immunohistochemical (IHC) proliferative markers, the prognostic value regarding the patients' overall survival (OS) or disease-free survival (DFS) has been confirmed for thymidylate synthase (TS), cyclin B1, cyclin D1, proliferating cell nuclear antigen (PCNA), and Ki-67. In most cases, the overexpression of these markers in tissues was related to worse OS and DFS. However, slowly proliferating cells should also be considered in CRC therapy (especially radiotherapy) as they could represent a reservoir from which cells are recruited to replenish the rapidly proliferating population in response to cell-damaging factors. Considering the above, the aim of this article is to review the most common proliferative markers assessed using various methods including IHC and selected molecular biology techniques (e.g., qRT-PCR, in situ hybridization, RNA/DNA sequencing, next-generation sequencing) as prognostic and predictive markers in CRC.

Cluster of Differentiation 44 Expression in Gastrointestinal Malignancies: A Study from South India

Introduction  Cancer stem cell markers are now being tried in various cancers as prognostic markers including GI cancer but these kinds of studies are sparse in Indian population. Materials and Methods  This study conducted over a period 50 months. Hematoxylin and eosin-stained slides were screened for grading of the tumor, extent of invasion of tumor, confirmation of metastasis, and staging was done. Immunohistochemical expression of CD44 was graded on the basis of percentage of tumor cells positive for staining. Statistical analysis was done and results were tabulated. Results : A total of 40 cases of GI cancer were studied. Ascending colon (37.5%) was the common site involved, 37 cases (92.5%) showed invasion beyond the muscularis externa. Most tumors were poorly differentiated (37.5%). Also, 50% of lymph nodes showed tumor deposits. The majority of the cases were in stage II (40%). There was a significant correlation between histopathological type of differentiation with lymph node metastasis and staging of tumor, lymph node metastasis also had significant association with staging. Grade 2, CD 44 expression was most common followed by Grade 3. Significant association was observed between histopathological differentiations of tumor with CD44 expression. Tumors that are invading beyond muscularis externa and lymph node-positive cases showed moderate to high CD44 expression. Conclusion  CD44 expression was significantly noted in poorly differentiated tumors. Increased expression was also noted in cases of tumors invading beyond muscularis externa and lymph node metastasis. Combination of CSC markers will increase the sensitivity and specificity and predict better overall survival in GI tumors.

Bazi Bushen alleviates skin senescence by orchestrating skin homeostasis in SAMP6 mice

Bazi Bushen, a Chinese-patented drug with the function of relieving fatigue and delaying ageing, has been proven effective for extenuating skin senescence. To investigate the potential mechanism, senescence-accelerated mouse prone 6 (SAMP6) was intragastrically administered with Bazi Bushen for 9 weeks to induce skin homeostasis. Skin homeostasis is important in mitigating skin senescence, and it is related to many factors such as oxidative stress, SASP, apoptosis, autophagy and stem cell. In our study, skin damage in SAMP6 mice was observed using HE, Masson and SA-β-gal staining. The content of hydroxyproline and the activities of SOD, MDA, GSH-PX and T-AOC in the skin were measured using commercial assay kits. The level of SASP factors (IL-6, IL-1β, TNF-α, MMP2 and MMP9) in skin were measured using ELISA kits. The protein expressions of p16, p21, p53, Bax, Bcl-2, Cleaved caspase-3, LC3, p62, Beclin1, OCT4, SOX2 and NANOG were measured by western blotting. The expression of ITGA6 and COL17A1 was measured by immunofluorescence staining and western blotting. Our findings demonstrated that Bazi Bushen alleviated skin senescence by orchestrating skin homeostasis, reducing the level of oxidative stress and the expression of SASP, regulating the balance of apoptosis and autophagy and enhancing the protein expressions of ITGA6 and COL17A1 to improve skin structure in SAMP6 mice. This study indicated that Bazi Bushen could serve as a potential therapy for alleviating skin senescence.

Deciphering the Role of p60AmotL2 in Epithelial Extrusion and Cell Detachment

Preserving an accurate cell count is crucial for maintaining homeostasis. Apical extrusion, a process in which redundant cells are eliminated by neighboring cells, plays a key role in this regard. Recent studies have revealed that apical extrusion can also be triggered in cells transformed by oncogenes, suggesting it may be a mechanism through which tumor cells escape their microenvironment. In previous work, we demonstrated that p60AmotL2 modulates the E-cadherin function by inhibiting its connection to radial actin filaments. This isoform of AmotL2 is expressed in invasive breast and colon tumors and promotes invasion in vitro and in vivo. Transcriptionally regulated by c-Fos, p60AmotL2 is induced by local stress signals such as severe hypoxia. In this study, we investigated the normal role of p60AmotL2 in epithelial tissues. We found that this isoform is predominantly expressed in the gut, where cells experience rapid turnover. Through time-lapse imaging, we present evidence that cells expressing p60AmotL2 are extruded by their normal neighboring cells. Based on these findings, we hypothesize that tumor cells exploit this pathway to detach from normal epithelia and invade surrounding tissues.

Metagenomic insights into the effects of cosmetics containing complex polysaccharides on the composition of skin microbiota in females

Introduction

The use of cosmetics has become a habit for women. However, their influence on the microbial diversity of the skin has rarely been studied.

Methods

Herein, the effect of cosmetics containing complex polysaccharides on the skin bacterial microbiota of female forehead and cheek areas was analyzed. Eighty volunteers were recruited and split into two groups (40 people each); one group was treated with cosmetics containing complex polysaccharides and the other with basic cream for 28 days. Skin samples were collected using sterilized cotton swabs, and 16S rDNA high-throughput sequencing was used to analyze the changes in skin bacterial microbiota composition before and after the intervention.

Results and discussion

A total of twenty-four phyla were detected in the forehead and cheek skin samples of 80 volunteers, the top three of which were Proteobacteria, Firmicutes, and Actinobacteria. The main genera of the forehead skin bacterial microbiota were Cutibacterium (11.1%), Acinetobacter (10.4%), Enterococcus (8.9%), Ralstonia (8.8%), and Staphylococcus (8.7%), while those of the cheek skin bacterial microbiota were Staphylococcus (20.0%), Ralstonia (8.7%), Propionibacterium (7.9%), Acinetobacter (7.2%), and Bifidobacterium (6.0%). Compared with basic cream, the use of cosmetics containing complex polysaccharides significantly increased the relative abundance of Staphylococcus and Bacillus in the forehead and cheek and reduced the relative abundance of Propionibacterium and Bifidobacterium. Thus, cosmetics containing complex polysaccharides could modify the composition of skin bacterial microbiota, which may help to maintain stable conditions of the skin.

Matrix obstructions cause multiscale disruption in collective epithelial migration by suppressing leader cell function

During disease and development, physical changes in extracellular matrix cause jamming, unjamming, and scattering in epithelial migration. However, whether disruptions in matrix topology alter collective cell migration speed and cell-cell coordination remains unclear. We microfabricated substrates with stumps of defined geometry, density, and orientation, which create obstructions for migrating epithelial cells. Here, we show that cells lose their speed and directionality when moving through densely spaced obstructions. Although leader cells are stiffer than follower cells on flat substrates, dense obstructions cause overall cell softening. Through a lattice-based model, we identify cellular protrusions, cell-cell adhesions, and leader-follower communication as key mechanisms for obstruction-sensitive collective cell migration. Our modeling predictions and experimental validations show that cells' obstruction sensitivity requires an optimal balance of cell-cell adhesions and protrusions. Both MDCK (more cohesive) and α-catenin-depleted MCF10A cells were less obstruction sensitive than wild-type MCF10A cells. Together, microscale softening, mesoscale disorder, and macroscale multicellular communication enable epithelial cell populations to sense topological obstructions encountered in challenging environments. Thus, obstruction-sensitivity could define "mechanotype" of cells that collectively migrate yet maintain intercellular communication.

Assessing Tumorigenicity in Stem Cell-Derived Therapeutic Products: A Critical Step in Safeguarding Regenerative Medicine

Stem cells hold promise in regenerative medicine due to their ability to proliferate and differentiate into various cell types. However, their self-renewal and multipotency also raise concerns about their tumorigenicity during and post-therapy. Indeed, multiple studies have reported the presence of stem cell-derived tumors in animal models and clinical administrations. Therefore, the assessment of tumorigenicity is crucial in evaluating the safety of stem cell-derived therapeutic products. Ideally, the assessment needs to be performed rapidly, sensitively, cost-effectively, and scalable. This article reviews various approaches for assessing tumorigenicity, including animal models, soft agar culture, PCR, flow cytometry, and microfluidics. Each method has its advantages and limitations. The selection of the assay depends on the specific needs of the study and the stage of development of the stem cell-derived therapeutic product. Combining multiple assays may provide a more comprehensive evaluation of tumorigenicity. Future developments should focus on the optimization and standardization of microfluidics-based methods, as well as the integration of multiple assays into a single platform for efficient and comprehensive evaluation of tumorigenicity.

miR-223: a key regulator of pulmonary inflammation

Small noncoding RNAs, known as microRNAs (miRNAs), are vital for the regulation of diverse biological processes. miR-223, an evolutionarily conserved anti-inflammatory miRNA expressed in cells of the myeloid lineage, has been implicated in the regulation of monocyte-macrophage differentiation, proinflammatory responses, and the recruitment of neutrophils. The biological functions of this gene are regulated by its expression levels in cells or tissues. In this review, we first outline the regulatory role of miR-223 in granulocytes, macrophages, endothelial cells, epithelial cells and dendritic cells (DCs). Then, we summarize the possible role of miR-223 in chronic obstructive pulmonary disease (COPD), acute lung injury (ALI), coronavirus disease 2019 (COVID-19) and other pulmonary inflammatory diseases to better understand the molecular regulatory networks in pulmonary inflammatory diseases.

Porcine Deltacoronavirus Infection Disrupts the Intestinal Mucosal Barrier and Inhibits Intestinal Stem Cell Differentiation to Goblet Cells via the Notch Signaling Pathway

Goblet cells and their secreted mucus are important elements of the intestinal mucosal barrier, which allows host cells to resist invasion by intestinal pathogens. Porcine deltacoronavirus (PDCoV) is an emerging swine enteric virus that causes severe diarrhea in pigs and causes large economic losses to pork producers worldwide. To date, the molecular mechanisms by which PDCoV regulates the function and differentiation of goblet cells and disrupts the intestinal mucosal barrier remain to be determined. Here, we report that in newborn piglets, PDCoV infection disrupts the intestinal barrier: specifically, there is intestinal villus atrophy, crypt depth increases, and tight junctions are disrupted. There is also a significant reduction in the number of goblet cells and the expression of MUC-2. In vitro, using intestinal monolayer organoids, we found that PDCoV infection activates the Notch signaling pathway, resulting in upregulated expression of HES-1 and downregulated expression of ATOH-1 and thereby inhibiting the differentiation of intestinal stem cells into goblet cells. Our study shows that PDCoV infection activates the Notch signaling pathway to inhibit the differentiation of goblet cells and their mucus secretion, resulting in disruption of the intestinal mucosal barrier. IMPORTANCE The intestinal mucosal barrier, mainly secreted by the intestinal goblet cells, is a crucial first line of defense against pathogenic microorganisms. PDCoV regulates the function and differentiation of goblet cells, thereby disrupting the mucosal barrier; however, the mechanism by which PDCoV disrupts the barrier is not known. Here, we report that in vivo, PDCoV infection decreases villus length, increases crypt depth, and disrupts tight junctions. Moreover, PDCoV activates the Notch signaling pathway, inhibiting goblet cell differentiation and mucus secretion in vivo and in vitro. Thus, our results provide a novel insight into the mechanism underlying intestinal mucosal barrier dysfunction caused by coronavirus infection.

The Scap-SREBP1-S1P/S2P lipogenesis signal orchestrates the homeostasis and spatiotemporal activation of NF-κB

The nuclear factor κB (NF-κB) pathway plays essential roles in innate and adaptive immunity, but little is known how NF-κB signaling is compartmentalized and spatiotemporally activated in the cytoplasm. Here, we show that the lipogenesis signal cascade Scap-SREBP1-S1P/S2P orchestrates the homeostasis and spatiotemporal activation of NF-κB. SREBP cleavage-activating protein (Scap) and sterol regulatory element-binding protein 1 (SREBP1) form a super complex with inhibitors of NF-κB α (IκBα) to associate NF-κB close to the endoplasmic reticulum (ER). Upon lipopolysaccharide (LPS) stimulation, Scap transports the complex to the Golgi apparatus, where SREBP1 is cleaved by site-1 protease (S1P)/S2P, liberating IκBα for IκB kinase (Ikk)-mediated phosphorylation and subsequent activation of NF-κB. Loss of Scap or inhibition of S1P or S2P diminishes, while SREBP1 deficiency augments, LPS-induced NF-κB activation and subsequent inflammatory responses. Our results reveal the Scap-SREBP1 complex as an additional cytoplasmic checkpoint for NF-κB homeostasis and unveil the Golgi apparatus as the optimal cellular platform for NF-κB activation, providing insights into the crosstalk between lipogenesis signaling and immunity.

Benzo [a] pyrene-loaded aged polystyrene microplastics promote colonic barrier injury via oxidative stress-mediated notch signalling

The adsorption of toxic substances on polystyrene microplastics (PSMPs) can modify their biological toxicity and exacerbate the threat to human health. The effects of benzo [a] pyrene (B (a) P)-loaded aged PSMPs on colonic barrier integrity remains unclear. Here, we showed that binding environmentally relevant concentrations of B (a) P alteredl̥ the physicochemical features and markedly enhanced the toxicity of PSMPs. Compared to pristine PSMP, PSMP@B (a) P promoted colonic barrier degradation, body weight loss, colon length shortening, oxidative stress (OS), autophagy, inflammation, and bacterial translocation. Microplastic (MP) exposure induced injury to the colon barrier, including tight junction (TJ) and mucosal barriers, via overactivation of the Notch signalling pathway under increased OS in mice and intestinal organoids. Notably, PSMP@B (a) P exposure exacerbated damage to TJ and the mucosal barrier via the overproduction of reactive oxygen species (ROS), which could be related to the release of B (a) P from PSMP@B (a) P induced by the acidic environment of autophagosomes, which in turn exert synergistic toxic effects with PSMPs. Our study elucidates some of the potential molecular mechanisms by which B (a) P enhances PSMP-related intestinal toxicity, which provides a potential therapeutic approach for diseases caused by PSMP@B (a)P and PSMP pollution.

Exercise improves homeostasis of the intestinal epithelium by activation of apelin receptor-AMP-activated protein kinase signalling

Intestinal remodelling is dynamically regulated by energy metabolism. Exercise is beneficial for gut health, but the specific mechanisms remain poorly understood. Intestine-specific apelin receptor (APJ) knockdown (KD) and wild-type male mice were randomly divided into two subgroups, with/without exercise, to obtain four groups: WT, WT with exercise, APJ KD and APJ KD with exercise. Animals in the exercise groups were subjected to daily treadmill exercise for 3 weeks. Duodenum was collected at 48 h after the last bout of exercise. AMP-activated protein kinase (AMPK) α1 KD and wild-type mice were also utilized for investigating the mediatory role of AMPK on exercise-induced duodenal epithelial development. AMPK and peroxisome proliferator-activated receptor γ coactivator-1 α were upregulated by exercise via APJ activation in the intestinal duodenum. Correspondingly, exercise induced permissive histone modifications in the PR domain containing 16 (PRDM16) promoter to activate its expression, which was dependent on APJ activation. In agreement, exercise elevated the expression of mitochondrial oxidative markers. The expression of intestinal epithelial markers was downregulated due to AMPK deficiency, and AMPK signalling facilitated epithelial renewal. These data demonstrate that exercise-induced activation of the APJ-AMPK axis facilitates the homeostasis of the intestinal duodenal epithelium. KEY POINTS: Apelin receptor (APJ) signalling is required for improved epithelial homeostasis of the small intestine in response to exercise. Exercise intervention activates PRDM16 through inducing histone modifications, enhanced mitochondrial biogenesis and fatty acid metabolism in duodenum. The morphological development of duodenal villus and crypt is enhanced by the muscle-derived exerkine apelin through the APJ-AMP-activated protein kinase axis.

Low temperature and mTOR inhibition favor stem cell maintenance in human keratinocyte cultures

Adult autologous human epidermal stem cells can be extensively expanded ex vivo for cell and gene therapy. Identifying the mechanisms involved in stem cell maintenance and defining culture conditions to maintain stemness is critical, because an inadequate environment can result in the rapid conversion of stem cells into progenitors/transient amplifying cells (clonal conversion), with deleterious consequences on the quality of the transplants and their ability to engraft. Here, we demonstrate that cultured human epidermal stem cells respond to a small drop in temperature through thermoTRP channels via mTOR signaling. Exposure of cells to rapamycin or a small drop in temperature induces the nuclear translocation of mTOR with an impact on gene expression. We also demonstrate by single-cell analysis that long-term inhibition of mTORC1 reduces clonal conversion and favors the maintenance of stemness. Taken together, our results demonstrate that human keratinocyte stem cells can adapt to environmental changes (e.g., small variations in temperature) through mTOR signaling and constant inhibition of mTORC1 favors stem cell maintenance, a finding of high importance for regenerative medicine applications.

Apple juice relieves loperamide-induced constipation in rats by downregulating the intestinal apical sodium-dependent bile acid transporter ASBT

Apples are known to exhibit various beneficial effects on human health. In the present study, we investigated the effect of continuous intake of apple juice (AJ) on constipation status. A single dose of loperamide in rats as the constipation model markedly decreased the weight and number of fecal pellets compared to saline-administered rats as a control. After the administration of AJ twice a day for seven days, recovery of defecation close to that of the control was observed in loperamide-treated rats. In addition, the total bile acid content in the feces increased from day 4 after the administration of AJ. Among hepatic and intestinal transporters and enzymes that regulate bile acids, the mRNA expression of the apical sodium-dependent bile acid transporter (Asbt, slc10a2) was decreased by AJ in rats. Furthermore, the Asbt-mediated bile acid transport activity in the rat ileum decreased after AJ administration. Moreover, in human colonic cancer-derived Caco-2 cells, AJ exposure for 24 and 48 h decreased the expressions of ASBT mRNA and protein, and the uptake activity of taurocholic acid in both 7- and 21-d cultures. Several components of AJ, such as procyanidins, decreased the expression of ASBT in Caco-2 cells. In conclusion, ASBT downregulation is a possible mechanism responsible for the constipation-relieving effect of apples, and procyanidins may play a role in downregulating ASBT, which leads to the beneficial effects of apples against constipation. Although it is generally agreed that the common dietary compositions play a role in constipation relief, the novel specific mechanism of apples found in this study would facilitate understanding food functions.

Role of FcγRIII in the nasal cavity of BALB/c mice in the primary amebic meningoencephalitis protection model

Different mechanisms of the host immune response against the primary amebic meningoencephalitis (PAM) in the mouse protection model have been described. It has been proposed that antibodies opsonize Naegleria fowleri trophozoites; subsequently, the polymorphonuclear cells (PMNs) surround the trophozoites to avoid the infection. FcγRs activate signaling pathways of adapter proteins such as Syk and Hck on PMNs to promote different effector cell functions which are induced by the Fc portion of the antibody-antigen complexes. In this work, we analyzed the activation of PMNs, epithelial cells, and nasal passage cells via the expression of Syk and Hck genes. Our results showed an increment of the FcγRIII and IgG subclasses in the nasal cavity from immunized mice as well as Syk and Hck expression was increased, whereas in the in vitro assay, we observed that when the trophozoites of N. fowleri were opsonized with IgG anti-N. fowleri and interacted with PMN, the expression of Syk and Hck was also increased. We suggest that PMNs are activated via their FcγRIII, which leads to the elimination of the trophozoites in vitro, while in the nasal cavity, the adhesion and consequently infection are avoided.

Junctional epithelium and hemidesmosomes: Tape and rivets for solving the "percutaneous device dilemma" in dental and other permanent implants

The percutaneous device dilemma describes etiological factors, centered around the disrupted epithelial tissue surrounding non-remodelable devices, that contribute to rampant percutaneous device infection. Natural percutaneous organs, in particular their extracellular matrix mediating the "device"/epithelium interface, serve as exquisite examples to inspire longer lasting long-term percutaneous device design. For example, the tooth's imperviousness to infection is mediated by the epithelium directly surrounding it, the junctional epithelium (JE). The hallmark feature of JE is formation of hemidesmosomes, cell/matrix adhesive structures that attach surrounding oral gingiva to the tooth's enamel through a basement membrane. Here, the authors survey the multifaceted functions of the JE, emphasizing the role of the matrix, with a particular focus on hemidesmosomes and their five main components. The authors highlight the known (and unknown) effects dental implant - as a model percutaneous device - placement has on JE regeneration and synthesize this information for application to other percutaneous devices. The authors conclude with a summary of bioengineering strategies aimed at solving the percutaneous device dilemma and invigorating greater collaboration between clinicians, bioengineers, and matrix biologists.

Maternal exercise improves epithelial development of fetal intestine by enhancing apelin signaling and oxidative metabolism

Obesity in pregnancy is currently the leading cause of gestational complications for the mother and fetus worldwide. Maternal obesity (MO), common in western societies, impedes development of intestinal epithelium in the fetuses, which causes disorders in the nutrient absorption and intestine-related immune responses in offspring. Here, using a mouse model of maternal exercise (ME), we found that exercise during pregnancy protects the impairment of fetal intestinal morphometrical formation and epithelial development due to MO. MO decreased villus length and epithelial proliferation markers in E18.5 fetal small intestine, which was increased due to ME. The expression of the epithelial differentiation markers, Lyz1, Muc2, and Tff3, in fetal small intestine was decreased due to MO, but protected by ME. Consistently, the biomarkers related to mitochondrial biogenesis and oxidative metabolism were downregulated in MO fetal small intestine but recovered by ME. Apelin injection to dams partially mirrored the beneficial effects of ME. ME and apelin injection activated AMPK, the downstream target of apelin receptor signaling, which might mediate the improvement of fetal epithelial development and oxidative metabolism. These findings suggest that ME, a highly accessible intervention, is effective in improving fetal intestinal epithelium of obese dams. Apelin-AMPK-mitochondrial biogenesis axis provides amenable therapeutic targets to facilitate fetal intestinal development of obese mothers.

Aloin A prevents ulcerative colitis in mice by enhancing the intestinal barrier function via suppressing the Notch signaling pathway

BACKGROUND

Previous studies reported that Aloe vera ameliorated DSS-induced colitis and promoted mucus secretion. However, the effect of Aloin A (AA), a major compound of Aloe vera, on colitis and its exact mechanism remains uncovered.

METHODS

C57BL/6 mice were successively subjected to 3% DSS solution for 5 days and distilled water for 2 days. Concurrently, AA (25, 50 mg/kg) and 5-aminosalicylic (500 mg/kg) were administrated intragastrically from day 1 to day 7. Colitis was evaluated by disease active index (DAI), colon length, inflammation response, and intestinal barrier function. In vitro LS174T cells challenged with 50 ng/ml of lipopolysaccharides (LPS) were used to validate the modulatory action of AA on the Notch signaling pathway.

RESULTS

Our results showed that oral administration with AA prominently prevented DSS-induced colitis symptoms in terms of decreased DAI, prevention of colon shortening, and reduced pathological damage. AA mitigated the inflammatory response evidenced by the decreased proinflammatory cytokines (TNF-α, IL-1β, IL-6) and increased anti-inflammatory cytokine (IL-10). Besides, AA inhibited apoptosis and facilitated proliferation in colons. Moreover, AA treatment up-regulated the expression of tight junction (TJ) proteins (ZO-1, Occludin) and promoted the secretion of MUC2 to decrease colon permeability. Mechanistically, AA inhibited the Notch pathway to promote the secretion of MUC2, which was consistent with LPS-challenged LS174 cells.

CONCLUSION

These results suggested that AA could prevent colitis by enhancing the intestinal barrier function via suppressing the Notch signaling pathway. Thus, AA might be a prospective remedy for ulcerative colitis.

Single shot quantitative polarized light imaging system for rapid planar biaxial testing of soft tissues

Quantitative Polarized Light Imaging (QPLI) is an established technique used to compute the orientation of collagen fibers based on their birefringence. QPLI systems typically require rotating linear polarizers to obtain sufficient data to estimate orientation, which limits acquisition speeds and is not ideal for its application to mechanical testing. In this paper, we present a QPLI system designed with no moving parts; a single shot technique which is ideal to characterize collagen fiber orientation and kinematics during mechanical testing. Our single shot QPLI system (ssQPLI) sorts polarized light into four linear polarization states that are collected simultaneously by four cameras. The ssQPLI system was validated using samples with known orientation and retardation, and we demonstrate its use with planar biaxial testing of mouse skin. The ssQPLI system was accurate with a mean orientation error of 1.35° ± 1.58°. Skin samples were tested with multiple loading protocols and in each case the mean orientation of the collagen network reoriented to align in the direction of primary loading as expected. In summary, the ssQPLI system is effective at quantifying collagen fiber organization, and, when combined with mechanical testing, can rapidly provide pixel-wise measures of fiber orientation during biaxial loading.

The molecular mechanisms and therapeutic strategies of EMT in tumor progression and metastasis

Epithelial–mesenchymal transition (EMT) is an essential process in normal embryonic development and tissue regeneration. However, aberrant reactivation of EMT is associated with malignant properties of tumor cells during cancer progression and metastasis, including promoted migration and invasiveness, increased tumor stemness, and enhanced resistance to chemotherapy and immunotherapy. EMT is tightly regulated by a complex network which is orchestrated with several intrinsic and extrinsic factors, including multiple transcription factors, post-translational control, epigenetic modifications, and noncoding RNA-mediated regulation. In this review, we described the molecular mechanisms, signaling pathways, and the stages of tumorigenesis involved in the EMT process and discussed the dynamic non-binary process of EMT and its role in tumor metastasis. Finally, we summarized the challenges of chemotherapy and immunotherapy in EMT and proposed strategies for tumor therapy targeting EMT.

Acute Foggy Corneal Epithelial Disease: Seeking Clinical Features and Risk Factors

(1) Purpose: Here, we describe the clinical characteristics and predisposing factors of acute foggy corneal epithelial disease, a rare disease newly found during COVID-19 pandemic; (2) Methods: In this single-arm, ambispective case series study, ten patients with acute foggy corneal epithelial disease admitted between May 2020 and March 2021 were enrolled. Their detailed medical history and clinical and ophthalmic findings were recorded and analyzed; (3) Results: All the patients were female (100%), aged from 28 to 61 years (mean age of 40.4 ± 9.3 years). Seven cases (70%) had excessive eye use, and six cases (60%) had stayed up late and were overworked. Ten subjects (100%) presented with acute onset and a self-healing tendency. There was a mild-to-moderate decrease in the corrected visual acuity (0.35 ± 0.21 (LogMAR)). Slit-lamp examination showed diffuse dust-like opacity and edema in the epithelial layer of the cornea. By in vivo confocal microscope, epithelial cells presented characteristically a “relief-like” appearance. Anterior segment optical coherence tomography examination revealed that the mean epithelial thickness was increased (69.25 ± 4.31 μm, p < 0.01); (4) Conclusions: Acute foggy corneal epithelial disease is a rare disease in clinic, which tends to occur in young and middle-aged females. The typical clinical symptom is sudden foggy vision, which occurs repeatedly and can be relieved without treatment. Sex, an abnormal menstrual cycle, overuse of the eyes, fatigue and pressure might be risk factors. Changes in lifestyle and eye use habit during the COVID-19 pandemic may have possibly contributed to this disease incidence.

Potential Therapeutic Role of Mesenchymal-Derived Stem Cells as an Alternative Therapy to Combat COVID-19 through Cytokines Storm

Medical health systems continue to be challenged due to newly emerging COVID-19, and there is an urgent need for alternative approaches for treatment. An increasing number of clinical observations indicate cytokine storms to be associated with COVID-19 severity and also to be a significant cause of death among COVID-19 patients. Cytokine storm involves the extensive proliferative and hyperactive activity of T and macrophage cells and the overproduction of pro-inflammatory cytokines. Stem cells are the type of cell having self-renewal properties and giving rise to differentiated cells. Currently, stem cell therapy is an exciting and promising therapeutic approach that can treat several diseases that were considered incurable in the past. It may be possible to develop novel methods to treat various diseases by identifying stem cells' growth and differentiation factors. Treatment with mesenchymal stem cells (MSCs) in medicine is anticipated to be highly effective. The present review article is organized to put forward the positive arguments and implications in support of mesenchymal stem cell therapy as an alternative therapy to cytokine storms, to combat COVID-19. Using the immunomodulatory potential of the MSCs, it is possible to fight against COVID-19 and counterbalance the cytokine storm.

Mesenchymal stem cells derived from the kidney can ameliorate diabetic nephropathy through the TGF-β/Smad signaling pathway

Diabetic nephropathy (DN) has been introduced as one of the main microvascular complications in diabetic patients, the most common cause of end-stage renal disease (ESRD). Based on the therapeutic potential of mesenchymal stem cells in tissue repair, we aimed to test the hypothesis that kidney stem cells (KSCs) might be effective in the kidney regeneration process. Stem cells from rat kidney were separated, and the surface stem cell markers were determined by flow cytometry analysis. Thirty-two Sprague Dawley rats were divided into four groups (control, control that received kidney stem cells, diabetic, diabetic treated with stem cells). To establish diabetic, model STZ (streptozotocin) (60 mg/kg) was used. The KSCs were injected into experimental groups via tail vein (2 × 106 cells/rat). In order to determine the impact of stem cells on the function and structure of the kidney, biochemical and histological parameters were measured. Further, the expression of miRNA-29a, miR-192, IL-1β, and TGF-β was determined through the real-time PCR technique. Phosphorylation of Smad2/3 was evaluated by using the standard western blotting. The KSCs significantly reduced blood nitrogen (BUN), serum creatinine (Scr), and 24-h urinary proteins in DN (P < 0.05). IL-1β and TGF-β significantly increased in the kidney of diabetic rats. In addition, the expression of miR-29a is significantly increased, whereas miR-192 decreased after treatment with KSCs (P < 0.05). Diabetic rats showed an increased level of phosphorylation of both Smad2 and Smad3 (P < 0.05). Periodic acid-Schiff (PAS) staining showed improved histopathological changes in the presence of KSCs. Stem cells derived from adult rat kidney may be an option for treating the early DN to improve the functions and structure of kidneys in rats with DN.

From Intestinal Epithelial Homeostasis to Colorectal Cancer: Autophagy Regulation in Cellular Stress

The intestinal epithelium is continuously exposed to abundant stress stimuli, which relies on an evolutionarily conserved process, autophagy, to maintain its homeostasis by degrading and recycling unwanted and damaged intracellular substances. Otherwise, disruption of this balance will result in the development of a wide range of disorders, including colorectal cancer (CRC). Dysregulated autophagy is implicated in the regulation of cellular responses to stress during the development, progression, and treatment of CRC. However, experimental investigations addressing the impact of autophagy in different phases of CRC have generated conflicting results, showing that autophagy is context-dependently related to CRC. Thus, both inhibition and activation of autophagy have been proposed as therapeutic strategies against CRC. Here, we will discuss the multifaceted role of autophagy in intestinal homeostasis and CRC, which may provide insights for future research directions.

Modelling human placental villous development: designing cultures that reflect anatomy

The use of in vitro tools to study trophoblast differentiation and function is essential to improve understanding of normal and abnormal placental development. The relative accessibility of human placentae enables the use of primary trophoblasts and placental explants in a range of in vitro systems. Recent advances in stem cell models, three-dimensional organoid cultures, and organ-on-a-chip systems have further shed light on the complex microenvironment and cell-cell crosstalk involved in placental development. However, understanding each model's strengths and limitations, and which in vivo aspects of human placentation in vitro data acquired does, or does not, accurately reflect, is key to interpret findings appropriately. To help researchers use and design anatomically accurate culture models, this review both outlines our current understanding of placental development, and critically considers the range of established and emerging culture models used to study this, with a focus on those derived from primary tissue.

Analysis and pharmacological modulation of senescence in human epithelial stem cells

Human epithelial stem cells (ESCs) are characterized by long‐term regenerative properties, much dependent on the tissue of origin and varying during their lifespan. We analysed such variables in cultures of ESCs isolated from the skin, conjunctiva, limbus and oral mucosa of healthy donors and patients affected by ectrodactyly‐ectodermal dysplasia‐clefting syndrome, a rare genetic disorder caused by mutations in the p63 gene. We cultured cells until exhaustion in the presence or in the absence of DAPT (γ‐secretase inhibitor; N‐[N‐(3, 5‐difluorophenacetyl)‐L‐alanyl]‐S‐phenylglycine T‐butyl ester). All cells were able to differentiate in vitro but exhibited variable self‐renewal potential. In particular, cells carrying p63 mutations stopped prematurely, compared with controls. Importantly, administration of DAPT significantly extended the replicative properties of all stem cells under examination. RNA sequencing analysis revealed that distinct sets of genes were up‐ or down‐regulated during their lifetime, thus allowing to identify druggable gene networks and off‐the‐shelf compounds potentially dealing with epithelial stem cell senescence. These data will expand our knowledge on the genetic bases of senescence and potentially pave the way to the pharmacological modulation of ageing in epithelial stem cells.

Human duodenal organoid-derived monolayers serve as a suitable barrier model for duodenal tissue

Usually, duodenal barriers are investigated using intestinal cell lines like Caco-2, which in contrast to native tissue are limited in cell-type representation. Organoids can consist of all intestinal cell types and are supposed to better reflect the in vivo situation. Growing three-dimensionally, with the apical side facing the lumen, application of typical physiological techniques to analyze the barrier is difficult. Organoid-derived monolayers (ODMs) were developed to overcome this. After optimizing culturing conditions, ODMs were characterized and compared to Caco-2 and duodenal tissue. Tight junction composition and appearance were analyzed, and electrophysiological barrier properties, like paracellular and transcellular barrier function and macromolecule permeability, were evaluated. Furthermore, transcriptomic data were analyzed. ODMs had tight junction protein expression and paracellular barrier properties much more resembling the originating tissue than Caco-2. Transcellular barrier was similar between ODMs and native tissue but was increased in Caco-2. Transcriptomic data showed that Caco-2 expressed fewer solute carriers than ODMs and native tissue. In conclusion, while Caco-2 cells differ mostly in transcellular properties, ODMs reflect trans- and paracellular properties of the originating tissue. If cultured under optimized conditions, ODMs possess reproducible functionality, and the variety of different cell types makes them a suitable model for human tissue-specific investigations.

Bone Marrow-Derived Cells Contribute to the Maintenance of Thymic Stroma including TECs

In paradox to critical functions for T-cell selection and self-tolerance, the thymus undergoes profound age-associated atrophy and loss of T-cell function, further enhanced by cancer therapies. Identifying thymic epithelial progenitor populations capable of forming functional thymic tissue will be critical in understanding thymic epithelial cell (TEC) ontogeny and designing strategies to reverse involution. We identified a new population of progenitor cells, present in both the thymus and bone marrow (BM) of mice, that coexpress the hematopoietic marker CD45 and the definitive thymic epithelial marker EpCAM and maintain the capacity to form functional thymic tissue. Confocal analysis and qRT-PCR of sorted cells from both BM and thymus confirmed coexpression of CD45 and EpCAM. Grafting of C57BL/6 fetal thymi under the kidney capsule of H2BGFP transgenic mice revealed that peripheral CD45+ EpCAM+ GFP-expressing cells migrate into the developing thymus and contribute to both TECs and FSP1-expressing thymic stroma. Sorted BM-derived CD45+ EpCAM+ cells contribute to reaggregate thymic organ cultures (RTOCs) and differentiate into keratin and FoxN1-expressing TECs, demonstrating that BM cells can contribute to the maintenance of TEC microenvironments previously thought to be derived solely from endoderm. BM-derived CD45+ EpCAM+ cells represent a new source of progenitor cells that contribute to thymic homeostasis. Future studies will characterize the contribution of BM-derived CD45+ EpCAM+ TEC progenitors to distinct functional TEC microenvironments in both the steady-state thymus and under conditions of demand. Cell therapies utilizing this population may help counteract thymic involution in cancer patients.