Epidermal stem cells are retained in vivo throughout skin aging

In healthy individuals, skin integrity is maintained by epidermal stem cells which self-renew and generate daughter cells that undergo terminal differentiation. It is currently unknown whether epidermal stem cells influence or are affected by skin aging. We therefore compared young and aged skin stem cell abundance, organization, and proliferation. We discovered that despite age-associated differences in epidermal proliferation, dermal thickness, follicle patterning, and immune cell abundance, epidermal stem cells were maintained at normal levels throughout life. These findings, coupled with observed dermal gene expression changes, suggest that epidermal stem cells themselves are intrinsically aging resistant and that local environmental or systemic factors modulate skin aging

Shape-Induced Terminal Differentiation of Human Epidermal Stem Cells Requires p38 and Is Regulated by Histone Acetylation

Engineered model substrates are powerful tools for examining interactions between stem cells and their microenvironment. Using this approach, we have previously shown that restricted cell adhesion promotes terminal differentiation of human epidermal stem cells via activation of serum response factor (SRF) and transcription of AP-1 genes. Here we investigate the roles of p38 MAPK and histone acetylation. Inhibition of p38 activity impaired SRF transcriptional activity and shape-induced terminal differentiation of human keratinocytes. In addition, inhibiting p38 reduced histone H3 acetylation at the promoters of SRF target genes, FOS and JUNB. Although histone acetylation correlated with SRF transcriptional activity and target gene expression, treatment with the histone de-acetylase inhibitor, trichostatin A (TSA) blocked terminal differentiation on micro-patterned substrates and in suspension. TSA treatment simultaneously maintained expression of LRIG1, TP63, and ITGB1. Therefore, global histone de-acetylation represses stem cell maintenance genes independent of SRF. Our studies establish a novel role for extrinsic physical cues in the regulation of chromatin remodeling, transcription, and differentiation of human epidermal stem cells

Myosin 10 is involved in murine pigmentation.

Myosins are molecular motors that are well known for their role in cell movement and contractile functions. Although extensively studied in muscle physiology, little is known about the function of myosins in mammalian skin. As part of the Sanger Institute Mouse Genetics Project, we have identified a role for Myo10 in pigmentation, with a phenotype unlike those of Myo5a or Myo7a. Adult mice homozygous for a disrupted Myo10 allele on a C57BL/6N background displayed a high degree of penetrance for white patches on their abdomen and dorsal surface. Forepaw syndactyly and hind paw syndactyly were also observed in these mice. Tail epidermal wholemounts showed a complete lack of melanocytes in the hair follicles and interfollicular epidermis. Myo10 has previously been implicated in human pigmentation. Our current study reveals involvement of Myo10 in murine skin pigmentation

A tumor-associated β1 integrin mutation that abrogates epithelial differentiation control

SCC4 human keratinocytes are derived from a squamous cell carcinoma of the tongue and undergo very little spontaneous differentiation. Introduction of a wild-type β1 integrin subunit into SCC4 cells stimulates differentiation, suggesting either that the cells have a defect in the integrin signaling pathways that control differentiation or that the β1 subunit itself is defective. Here we describe a heterozygous mutation in the SCC4 β1 subunit. The mutation, T188I, maps to the I-like domain. It results in constitutive activation of ligand binding, irrespective of the partner α subunit, in solid phase assays with recombinant protein and in living cells. The mutation promotes cell spreading, but not proliferation, motility, or invasiveness. It results in sustained activation of Erk MAPK independent of cell spreading. When introduced into SCC4 keratinocytes, the wild-type β1 integrin stimulates differentiation, whereas the mutant is inactive. Activation of β1 integrins in normal keratinocytes also suppresses differentiation. These results establish, for the first time, mutation as a mechanism by which integrins can contribute to neoplasia, because the degree of differentiation in epithelial cancers is inversely correlated with prognosis. They also provide new insights into how integrins regulate keratinocyte differentiation

The therapeutic potential of stem cells

In recent years, there has been an explosion of interest in stem cells, not just within the scientific and medical communities but also among politicians, religious groups and ethicists. Here, we summarize the different types of stem cells that have been described: their origins in embryonic and adult tissues and their differentiation potential in vivo and in culture. We review some current clinical applications of stem cells, highlighting the problems encountered when going from proof-of-principle in the laboratory to widespread clinical practice. While some of the key genetic and epigenetic factors that determine stem cell properties have been identified, there is still much to be learned about how these factors interact. There is a growing realization of the importance of environmental factors in regulating stem cell behaviour and this is being explored by imaging stem cells in vivo and recreating artificial niches in vitro. New therapies, based on stem cell transplantation or endogenous stem cells, are emerging areas, as is drug discovery based on patient-specific pluripotent cells and cancer stem cells. What makes stem cell research so exciting is its tremendous potential to benefit human health and the opportunities for interdisciplinary research that it presents

Factors influencing implementation and sustainability of interventions to improve oral health and related health behaviours in adults experiencing severe and multiple disadvantage: a mixed-methods systematic review

OBJECTIVES: Among people experiencing severe and multiple disadvantage (SMD), poor oral health is common and linked to smoking, substance use and high sugar intake. Studies have explored interventions addressing oral health and related behaviours; however, factors related to the implementation of these interventions remain unclear. This mixed-methods systematic review aimed to synthesise evidence on the implementation and sustainability of interventions to improve oral health and related health behaviours among adults experiencing SMD. METHODS: Bibliographic databases (MEDLINE, EMBASE, PsycINFO, CINAHL, EBSCO, Scopus) and grey literature were searched from inception to February 2023. Studies meeting the inclusion criteria were screened and extracted independently by two researchers. Quality appraisal was undertaken, and results were synthesised using narrative and thematic analyses. RESULTS: Seventeen papers were included (published between 1995 and 2022). Studies were mostly of moderate quality and included views from SMD groups and service providers. From the qualitative synthesis, most findings were related to aspects such as trust, resources and motivation levels of SMD groups and service providers. None of the studies reported on diet and none included repeated offending (one of the aspects of SMD). From the quantitative synthesis, no difference was observed in programme attendance between the interventions and usual care, although there was some indication of sustained improvements in participation in the intervention group. CONCLUSION: This review provides some evidence that trust, adequate resources and motivation levels are potentially important in implementing interventions to improve oral health and substance use among SMD groups. Further research is needed from high quality studies and focusing on diet in this population. PROSPERO REGISTRATION NUMBER: CRD42020202416

Improving the Quality of Dentistry (IQuaD):a cluster factorial randomised controlled trial comparing the effectiveness and cost-benefit of oral hygiene advice and/or periodontal instrumentation with routine care for the prevention and management of periodontal disease in dentate adults attending dental primary care

Acknowledgements The authors wish to thank Mark Forrest and the programming team at CHaRT; Cynthia Fraser, our information specialist, for assistance with referencing; Moira Swan, who was the dental research nurse and part of the OA team in Newcastle upon Tyne; Louise Campbell for secretarial support and data management; our original statistician in the group, Andy Elders; senior IT manager Gladys Macpherson; senior trial administrator at the TCOD Marilyn Laird; Luke Vale for his involvement with the design of the health economic analysis at the inception of the trial; Maria Dimitrova, who assisted the health economists in the collection of unit costs; staff of the Scottish Primary Care Research Network, who assisted with screening eligible patients at dental practices; staff of the North East Commissioning Support Unit who assisted with research payments to dental practices in the north-east; members of the TMC and Periodontal Advisory Group for their ongoing advice and support of the trial; the independent members of the TSC and DMC; and the staff at recruitment sites who facilitated recruitment, treatment and follow-up of trial participants. The Health Services Research Unit and the Health Economics Research Unit is core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorate.Peer reviewedPublisher PD

Lrig1 marks a population of gastric epithelial cells capable of long-term tissue maintenance and growth in vitro

The processes involved in renewal of the epithelium that lines the mouse stomach remain unclear. Apart from the cells in the isthmus, several other populations located deeper in the gastric glands have been suggested to contribute to the maintenance of the gastric epithelium. Here, we reveal that Lrig1 is expressed in the basal layer of the forestomach and the lower part of glands in the corpus and pylorus. In the glandular epithelium of the stomach, Lrig1 marks a heterogeneous population comprising mainly non-proliferative cells. Yet, fate-mapping experiments using a knock-in mouse line expressing Cre specifically in Lrig1(+) cells demonstrate that these cells are able to contribute to the long-term maintenance of the gastric epithelium. Moreover, when cultured in vitro, cells expressing high level of Lrig1 have much higher organoid forming potential than the corresponding cellular populations expressing lower levels of Lrig1. Taken together, these observations show that Lrig1 is expressed primarily by differentiated cells, but that these cells can be recruited to contribute to the maintenance of the gastric epithelium. This confirms previous observations that cells located in the lower segments of gastric glands can participate in tissue replenishment

Identification of genes important for cutaneous function revealed by a large scale reverse genetic screen in the mouse.

The skin is a highly regenerative organ which plays critical roles in protecting the body and sensing its environment. Consequently, morbidity and mortality associated with skin defects represent a significant health issue. To identify genes important in skin development and homeostasis, we have applied a high throughput, multi-parameter phenotype screen to the conditional targeted mutant mice generated by the Wellcome Trust Sanger Institute's Mouse Genetics Project (Sanger-MGP). A total of 562 different mouse lines were subjected to a variety of tests assessing cutaneous expression, macroscopic clinical disease, histological change, hair follicle cycling, and aberrant marker expression. Cutaneous lesions were associated with mutations in 23 different genes. Many of these were not previously associated with skin disease in the organ (Mysm1, Vangl1, Trpc4ap, Nom1, Sparc, Farp2, and Prkab1), while others were ascribed new cutaneous functions on the basis of the screening approach (Krt76, Lrig1, Myo5a, Nsun2, and Nf1). The integration of these skin specific screening protocols into the Sanger-MGP primary phenotyping pipelines marks the largest reported reverse genetic screen undertaken in any organ and defines approaches to maximise the productivity of future projects of this nature, while flagging genes for further characterisation

Investigating the effectiveness and acceptability of oral health and related health behaviour interventions in adults with severe and multiple disadvantage:Protocol for a mixed-methods systematic review

Increasing numbers of people in England experience homelessness, substance use, and repeated offending (known as ‘severe and multiple disadvantage’; SMD). Populations experiencing SMD often have extremely poor oral health, which is closely inter-linked with high levels of substance use, smoking, and poor diet. This study aims to undertake an evidence synthesis to identify the effectiveness, resource requirements, and factors influencing the implementation and acceptability of oral health and related health behaviour interventions in adults experiencing SMD. Two systematic reviews will be conducted using mixed-methods. Review 1 will investigate the effectiveness and resource implications of oral health and related health behaviours (substance use, smoking, diet) interventions; Review 2 will investigate factors influencing the implementation of such interventions. The population includes adults (≥18 years) experiencing SMD. Standard review methods in terms of searches, screening, data extraction, and quality appraisal will be conducted. Narrative syntheses will be conducted. If feasible, a meta-analysis will be conducted for Review 1 and a thematic synthesis for Review 2. Evidence from the two reviews will then be synthesised together. Input from people with experience of SMD will be sought throughout to inform the reviews. An initial logic model will be iteratively refined during the review.</jats:p