Aging of intestinal stem cells

Immunohistochemical evaluation of LGR5, CD71, CD138 and CXCR3 markers in the small bowel mucosa of participants with celiac disease and persons with normal bowel mucosa

Celiac disease (CD) is a chronic autoimmune disease of the small bowel mucosa that develops because of the altered immune response to gluten, which leads to intestinal epithelium damage and villous atrophy. However, studies on regeneration of the damaged small bowel mucosa and density of intestinal stem cells (ISC) in CD persons are still scarce. We aimed to evaluate the number of small bowel mucosa cells positive for LGR5, CD138/Syndecan-1, CD71 and CXCR3 in CD and in controls with normal bowel mucosa; to find relationship between these markers and degree of small intestinal atrophy and to compare these results with our previous data about the number of CD103 + , IDO + DCs, FOXP3 + Tregs, enterovirus (EV) density and serum zonulin level. The paraffin sections of the small bowel biopsies were obtained from 26 children with CD (median age 6.5 years), and from 20 controls with normal intestinal mucosa (median age 14.2 years) and from the tissue bank of the Department of Pathology of Tartu University Hospital (from 18 participants with CD including 14 children (median age 13.2 years) and from 11subjects with normal small bowel mucosa, including one child aged 4.8 years. The number of LGR5 + , CD71 + , CD138 + , and CXCR3 + cells was evaluated using immunohistochemistry. The median number of CD138 + and CXCR3 + cells was significantly higher in the small bowel mucosa in CD compared with normal mucosa (p = 0.0002 for CD138 and p = 0.006 for CXCR3). The median number of CD71 + cells was significantly higher in normal small bowel mucosa (p = 0.005). The number of LGR5 + cells did not differ between persons with CD and those with normal small bowel mucosa (p = 0.7). A markedly increased number of CD138 + and CXCR3 + cells in the small bowel mucosa of participants with CD confirms their role in the pathogenesis of this disease. There was no expected marked difference in the density of any of the studied markers between lower or higher grade of small bowel atrophy and level of tTG-IgA in CD.

Bioactive fraction of Musa balbisiana seed mitigates D-galactose-induced brain aging via SIRT1/PGC-1α/FoxO3a activation and intestinal barrier dysfunction by modulating gut microbiota and core metabolites

Aging is an inevitable biological process, and emerging research has highlighted the potential of dietary and pharmacological interventions to decelerate the trajectory of age-related diseases and prolong the health span. This study evaluates the protective effects of Musa balbisiana seed on healthy aging using D-galactose-induced accelerated aging rats. The results suggested that the bioactive ethyl acetate fraction of Musa balbisiana seed extract (BF) exhibited protective effects against aging-induced oxidative stress by reducing oxidative DNA damage, advanced glycation end-product formation, and malondialdehyde levels while restoring antioxidant and glyoxalase enzyme activities. BF also ameliorated neurodegeneration by decreasing acetylcholinesterase enzyme activity and amyloid beta plaque formation. Histopathological analysis demonstrated the protective effects of BF against brain aging, liver disruption, renal damage, and intestinal barrier dysfunction. BF further restored intestinal permeability by upregulating the tight junctions (zonula occludens 1 and 2, claudin 1,2,3 and 4, and occludin) and mucin (mucin 2 and mucin 5ac) gene expression while downregulating the expression of inflammatory cytokines (IL-1β, IL-6, and TNF-α). BF significantly induced the phosphorylation of FoxO3a proteins and upregulated the gene expression of SIRT1, PGC-1α, and TFAM in the hippocampus. Next-generation sequencing (NGS) of 16s rRNA amplicons of fecal metagenomics DNA and metabolites profiling showed that BF intervention restructured the gut microbiota and altered core metabolites related to cholesterol metabolism. Overall, our findings demonstrated the multifaceted protective effects of Musa balbisiana seed against D-galactose-induced aging.

The senotherapeutic potential of phytochemicals for age-related intestinal disease

During the last few decades, life expectancy has increased worldwide along with the prevalence of several age-related diseases. Among aging pathways, cellular senescence and chronic inflammation (or "inflammaging") appear to be connected to gut homeostasis and dysbiosis of the microbiome. Cellular senescence is a state of essentially irreversible cell cycle arrest that occurs in response to stress. Although senescent cells (SC) remain metabolically active, they do not proliferate and can secrete inflammatory and other factors comprising the senescence-associated secretory phenotype (SASP). Accumulation of SCs has been linked to onset of several age-related diseases, in the brain, bones, the gastrointestinal tract, and other organs and tissues. The gut microbiome undergoes substantial changes with aging and is tightly interconnected with either successful (healthy) aging or disease. Senotherapeutic drugs are compounds that can clear senescent cells or modulate the release of SASP factors and hence attenuate the impact of the senescence-associated pro-inflammatory state. Phytochemicals, phenolic compounds and terpenes, which have antioxidant and anti-inflammatory activities, could also be senotherapeutic given their ability to act upon senescence-linked cellular pathways. The aim of this review is to dissect links among the gut microbiome, cellular senescence, inflammaging, and disease, as well as to explore phytochemicals as potential senotherapeutics, focusing on their interactions with gut microbiota. Coordinated targeting of these inter-related processes might unveil new strategies for promoting healthy aging.

Initial pig developmental stage influences intestinal organoid growth but not cellular composition

BACKGROUND

Intestinal organoids are promising tools in the context of animal experiment reduction but a thorough characterization of the impact of the origin of intestinal stem cells (ISC) on organoid phenotype is needed to routinely use this cellular model. Our objective was to evaluate the effect of ISC donor age on the growth, morphology and cellular composition of intestinal organoids derived from pig.

METHODS

Organoids were derived from jejunal and colonic ISC obtained from 1-, 7-, 28-, 36- and 180-day-old pigs and passaged three times.

RESULTS

We first confirmed by qPCR that the expression of 18% of the >80 studied genes related to various intestinal functions differed between jejunal and colonic organoids after two passages (p < 0.05). Growth and morphology of organoids depended on intestinal location (greater number and larger organoids derived from colonic than jejunal ISC, p < 0.05) but also pig age. Indeed, when ISC were derived from young piglets, the ratio of organoids to spheroids was greater (p < 0.05), spheroids were larger during the primary culture but smaller after two passages (p < 0.05) and organoids were smaller after one passage (p > 0.05) compared to ISC from older pigs. Finally, no difference in cellular composition, evaluated by immunostaining of markers of the major intestinal cell types (absorptive, enteroendocrine and goblet cells) was observed between organoids originating from 7- or 180-day-old pigs, but differences between intestinal site origins were noticed.

CONCLUSION

In conclusion, while the age of the tissue donor affected organoid growth and morphology, it did not influence the phenotype.

Targeting CDC42 reduces skeletal degeneration after hematopoietic stem cell transplantation

ABSTRACT

Osteopenia and osteoporosis are common long-term complications of the cytotoxic conditioning regimen for hematopoietic stem cell transplantation (HSCT). We examined mesenchymal stem and progenitor cells (MSPCs), which include skeletal progenitors, from mice undergoing HSCT. Such MSPCs showed reduced fibroblastic colony-forming units frequency, increased DNA damage, and enhanced occurrence of cellular senescence, whereas there was a reduced bone volume in animals that underwent HSCT. This reduced MSPC function correlated with elevated activation of the small Rho guanosine triphosphate hydrolase CDC42, disorganized F-actin distribution, mitochondrial abnormalities, and impaired mitophagy in MSPCs. Changes and defects similar to those in mice were also observed in MSPCs from humans undergoing HSCT. A pharmacological treatment that attenuated the elevated activation of CDC42 restored F-actin fiber alignment, mitochondrial function, and mitophagy in MSPCs in vitro. Finally, targeting CDC42 activity in vivo in animals undergoing transplants improved MSPC quality to increase both bone volume and trabecular bone thickness. Our study shows that attenuation of CDC42 activity is sufficient to attenuate reduced function of MSPCs in a BM transplant setting.

Gut aging: A wane from the normal to repercussion and gerotherapeutic strategies

Globally, age-related diseases represent a significant public health concern among the elderly population. In aging, healthy organs and tissues undergo structural and functional changes that put the aged adults at risk of diseases. Some of the age-related diseases include cancer, atherosclerosis, brain disorders, muscle atrophy (sarcopenia), gastrointestinal (GIT) disorders, etc. In organs, a decline in stem cell function is the starting point of many conditions and is extremely important in GIT disorder development. Many studies have established that aging affects stem cells and their surrounding supportive niche components. Although there is a significant advancement in treating intestinal aging, the rising elderly population coupled with a higher occurrence of chronic gut ailments necessitates more effective therapeutic approaches to preserve gut health. Notable therapeutic strategies such as Western medicine, traditional Chinese medicine, and other health-promotion interventions have been reported in several studies to hold promise in mitigating age-related gut disorders. This review highlights findings across various facets of gut aging with a focus on aging-associated changes of intestinal stem cells and their niche components, thus a deviation from the normal to repercussion, as well as essential therapeutic strategies to mitigate intestinal aging.

Sex as a biological variable in ageing: insights and perspectives on the molecular and cellular hallmarks

Sex-specific differences in lifespan and ageing are observed in various species. In humans, women generally live longer but are frailer and suffer from different age-related diseases compared to men. The hallmarks of ageing, such as genomic instability, telomere attrition or loss of proteostasis, exhibit sex-specific patterns. Sex chromosomes and sex hormones, as well as the epigenetic regulation of the inactive X chromosome, have been shown to affect lifespan and age-related diseases. Here we review the current knowledge on the biological basis of sex-biased ageing. While our review is focused on humans, we also discuss examples of model organisms such as the mouse, fruit fly or the killifish. Understanding these molecular differences is crucial as the elderly population is expected to double worldwide by 2050, making sex-specific approaches in the diagnosis, treatment, therapeutic development and prevention of age-related diseases a pressing need.

The intestinal stem cell as a target: A review

Human intestinal epithelium handles several events that may affect health. It is composed of villi and crypts, which contain different types of cells. Each cell type plays an essential role in intestinal functions, including absorption, defense, self-renewal, and regeneration. Intestinal stem cells (ISCs), located at the base of intestinal crypts, play an important role in intestinal homeostasis and renewal. Any disruption in intestinal homeostasis, in which ISCs alter their function, may result in tumor growth. As Wnt and Notch signaling pathways are essential for ISCs homeostasis and for maintaining self-renewal, any defects in these pathways could increase the risk of developing colorectal cancer (CRC). Lgr5+ cells have been identified as intestinal stem cells expressing a leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), which is involved in the regulation of Wnt signaling. Several studies have reported upregulated expression of LGR5 in CRC. Hence, in this review, we discuss the relationship between LGR5, Wnt signaling, and Notch signaling and the development of CRC, as well as recent therapeutic strategies targeting LGR5, cancer stem cells (CSCs), and the aforementioned signaling pathways.

Nonlinear DNA methylation trajectories in aging male mice

Although DNA methylation data yields highly accurate age predictors, little is known about the dynamics of this quintessential epigenomic biomarker during lifespan. To narrow the gap, we investigate the methylation trajectories of male mouse colon at five different time points of aging. Our study indicates the existence of sudden hypermethylation events at specific stages of life. Precisely, we identify two epigenomic switches during early-to-midlife (3-9 months) and mid-to-late-life (15-24 months) transitions, separating the rodents' life into three stages. These nonlinear methylation dynamics predominantly affect genes associated with the nervous system and enrich in bivalently marked chromatin regions. Based on groups of nonlinearly modified loci, we construct a clock-like classifier STageR (STage of aging estimatoR) that accurately predicts murine epigenetic stage. We demonstrate the universality of our clock in an independent mouse cohort and with publicly available datasets.

The secreted protein Amuc_1409 from Akkermansia muciniphila improves gut health through intestinal stem cell regulation

Akkermansia muciniphila has received great attention because of its beneficial roles in gut health by regulating gut immunity, promoting intestinal epithelial development, and improving barrier integrity. However, A. muciniphila-derived functional molecules regulating gut health are not well understood. Microbiome-secreted proteins act as key arbitrators of host-microbiome crosstalk through interactions with host cells in the gut and are important for understanding host-microbiome relationships. Herein, we report the biological function of Amuc_1409, a previously uncharacterised A. muciniphila-secreted protein. Amuc_1409 increased intestinal stem cell (ISC) proliferation and regeneration in ex vivo intestinal organoids and in vivo models of radiation- or chemotherapeutic drug-induced intestinal injury and natural aging with male mice. Mechanistically, Amuc_1409 promoted E-cadherin/β-catenin complex dissociation via interaction with E-cadherin, resulting in the activation of Wnt/β-catenin signaling. Our results demonstrate that Amuc_1409 plays a crucial role in intestinal homeostasis by regulating ISC activity in an E-cadherin-dependent manner and is a promising biomolecule for improving and maintaining gut health.

The loss of antioxidant activities impairs intestinal epithelium homeostasis by altering lipid metabolism

Reactive oxygens species (ROS) are common byproducts of metabolic reactions and could be at the origin of many diseases of the elderly. Here we investigated the role of ROS in the renewal of the intestinal epithelium in mice lacking catalase (CAT) and/or nicotinamide nucleotide transhydrogenase (NNT) activities. Cat-/- mice have delayed intestinal epithelium renewal and were prone to develop necrotizing enterocolitis upon starvation. Interestingly, crypts lacking CAT showed fewer intestinal stem cells (ISC) and lower stem cell activity than wild-type. In contrast, crypts lacking NNT showed a similar number of ISCs as wild-type but increased stem cell activity, which was also impaired by the loss of CAT. No alteration in the number of Paneth cells (PCs) was observed in crypts of either Cat-/- or Nnt-/- mice, but they showed an evident decline in the amount of lysozyme. Cat deficiency caused fat accumulation in crypts, and a fall in the remarkable high amount of adipose triglyceride lipase (ATGL) in PCs. Notably, the low levels of ATGL in the intestine of Cat -/- mice increased after a treatment with the antioxidant N-acetyl-L-cysteine. Supporting a role of ATGL in the regulation of ISC activity, its inhibition halt intestinal organoid development. These data suggest that the reduction in the renewal capacity of intestine originates from fatty acid metabolic alterations caused by peroxisomal ROS.

ECM and epithelial stem cells: the scaffold of destiny

Adult stem cells play a critical role in maintaining tissue homeostasis and promoting longevity. The intricate organization and presence of common markers among adult epithelial stem cells in the intestine, lung, and skin serve as hallmarks of these cells. The specific location pattern of these cells within their respective organs highlights the significance of the niche in which they reside. The extracellular matrix (ECM) not only provides physical support but also acts as a reservoir for various biochemical and biophysical signals. We will consider differences in proliferation, repair, and regenerative capacities of the three epithelia and review how environmental cues emerging from the niche regulate cell fate. These cues are transduced via mechanosignaling, regulating gene expression, and bring us to the concept of the fate scaffold. Understanding both the analogies and discrepancies in the mechanisms that govern stem cell fate in various organs can offer valuable insights for rejuvenation therapy and tissue engineering.

Evidence that the loss of colonic anti-microbial peptides may promote dysbiotic Gram-negative inflammaging-associated bacteria in aging mice

Introduction: Aging studies in humans and mice have played a key role in understanding the intestinal microbiome and an increased abundance of "inflammaging" Gram-negative (Gn) bacteria. The mechanisms underlying this inflammatory profile in the aging microbiome are unknown. We tested the hypothesis that an aging-related decrease in colonic crypt epithelial cell anti-microbial peptide (AMP) gene expression could promote colonic microbiome inflammatory Gn dysbiosis and inflammaging. Methods: As a model of aging, C57BL/6J mice fecal (colonic) microbiota (16S) and isolated colonic crypt epithelial cell gene expression (RNA-seq) were assessed at 2 months (mth) (human: 18 years old; yo), 15 mth (human: 50 yo), and 25 mth (human: 84 yo). Informatics examined aging-related microbial compositions, differential colonic crypt epithelial cell gene expressions, and correlations between colonic bacteria and colonic crypt epithelial cell gene expressions. Results: Fecal microbiota exhibited significantly increased relative abundances of pro-inflammatory Gn bacteria with aging. Colonic crypt epithelial cell gene expression analysis showed significant age-related downregulation of key AMP genes that repress the growth of Gn bacteria. The aging-related decrease in AMP gene expressions is significantly correlated with an increased abundance in Gn bacteria (dysbiosis), loss of colonic barrier gene expression, and senescence- and inflammation-related gene expression. Conclusion: This study supports the proposed model that aging-related loss of colonic crypt epithelial cell AMP gene expression promotes increased relative abundances of Gn inflammaging-associated bacteria and gene expression markers of colonic inflammaging. These data may support new targets for aging-related therapies based on intestinal genes and microbiomes.

Single cell analysis revealed that two distinct, unique CD4+ T cell subsets were increased in the small intestinal intraepithelial lymphocytes of aged mice

Recent advances in research suggest that aging has a controllable chronic inflammatory disease aspect. Aging systemic T cells, which secrete pro-inflammatory factors, affect surrounding somatic cells, and accelerate the aging process through chronic inflammation, have attracted attention as potential therapeutic targets in aging. On the other hand, there are few reports on the aging of the intestinal immune system, which differs from the systemic immune system in many ways. In the current study, we investigated the age-related changes in the intestinal immune system, particularly in T cells. The most significant changes were observed in the CD4+ T cells in the small intestinal IEL, with a marked increase in this fraction in old mice and reduced expression of CD27 and CD28, which are characteristic of aging systemic T cells. The proliferative capacity of aging IEL CD4+ T cells was significantly more reduced than that of aging systemic T cells. Transcriptome analysis showed that the expression of inflammatory cytokines was not upregulated, whereas Cd8α, NK receptors, and Granzymes were upregulated in aging IEL CD4+ T cells. Functional analysis showed that aging IEL T cells had a higher cytotoxic function against intestinal tumor organoids in vitro than young IEL T cells. scRNAseq revealed that splenic T cells show a transition from naïve to memory T cells, whereas intestinal T cells show the emergence of a CD8αα+CD4+ T cell fraction in aged mice, which is rarely seen in young cells. Further analysis of the aging IEL CD4+ T cells showed that two unique subsets are increased that are distinct from the systemic CD4+ T cells. Subset 1 has a pro-inflammatory component, with expression of IFNγ and upregulation of NFkB signaling pathways. Subset 2 does not express IFNγ, but upregulates inhibitory molecules and nIEL markers. Expression of granzymes and Cd8a was common to both. These fractions were in opposite positions in the clustering by UMAP and had different TCR repertoires. They may be involved in the suppression of intestinal aging and longevity through anti-tumor immunity, elimination of senescent cells and stressed cells in the aging environment. This finding could be a breakthrough in aging research.

Ginseng promotes the function of intestinal stem cells through the Wnt/β-catenin signaling pathway in D-galactose-induced aging mice

BACKGROUND

Intestinal stem cells (ISCs) are the reservoir source of various types of intestinal cells, and the decline of stem cell function in the gut may be a potential factor for aging-related disease. The present study aimed to explore the regulatory mechanisms of Panax ginseng C.A.Meyer (Araliaceae, Panax genus) that could restore gut aging by enhancing intestinal function and regulating ISCs in aging mice based on the Wnt/β-catenin signaling pathway.

METHODS

A total of 60 ICR male mice were randomly divided into control, model, metformin, and ginseng water decoction (GWD) 3.6, 1.8, and 0.9 g/kg groups. The aging model was induced by 1 % D-galactose (s.c. 0.1 mL/10 g) for 28 days. Moreover, GWD was given to aging mice intragastrically (i.g.) once a day for 28 successive days. The learning memory ability, pathological status, and function in the ileum tissue, the activity of digestive enzymes, and short-chain fatty acid (SCFA) content in the colon were evaluated, and the related mechanism was investigated.

RESULTS

Ginseng can decrease the escape latency time and increase the swimming speed and the number of crossing platforms in aging mice. Moreover, the pathology of ileum tissue improved, the length of the intestinal villi increased, and the width of the villi and the depth of the crypts decreased. The activities of trypsin, α-amylase, and lipase increased in duodenal content and intestinal mucosa. In the colon, the content of SCFA, such as acetic acid, propionic acid and butyric acid, increased, indicating that ginseng significantly improves intestinal function impairment. The mRNA expressions and protein levels of β-catenin, C-myc, GSK-3β, Lgr5, and Olfm4 were upregulated in the ginseng group.

CONCLUSIONS

Ginseng improves intestinal function and regulates the function of ISCs in order to protect intestinal health by activating the Wnt/β-catenin signaling pathway in aging mice.

Glutamine boosts intestinal stem cell-mediated small intestinal epithelial development during early weaning: Involvement of WNT signaling

Early weaning usually causes small intestine epithelial development abnormality, increasing the risk of gastrointestinal diseases. Glutamine (Gln), enriching in plasma and milk, is widely reported to benefit intestinal health. However, whether Gln affects intestinal stem cell (ISC) activity in response to early weaning is unclear. Here, both the early weaning mice and intestinal organoids were used to study the role of Gln in regulating ISC activities. Results showed that Gln ameliorated early weaning-induced epithelial atrophy and augmented the ISC-mediated epithelial regeneration. Gln deprivation disabled ISC-mediated epithelial regeneration and crypt fission in vitro. Mechanistically, Gln augmented WNT signaling in a dose-dependent manner to regulate ISC activity, while WNT signaling blockage abolished the effects of Gln on ISCs. Together, Gln accelerates stem cell-mediated intestinal epithelial development associated with the augmentation of WNT signaling, which provides novel insights into the mechanism by which Gln promotes intestinal health.

Stem Cell Therapy in Inflammatory Bowel Disease: A Review of Achievements and Challenges

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a group of chronic inflammatory diseases of the gastrointestinal tract. Repeated inflammation can lead to complications, such as intestinal fistula, obstruction, perforation, and bleeding. Unfortunately, achieving durable remission and mucosal healing (MH) with current treatments is difficult. Stem cells (SCs) have the potential to modulate immunity, suppress inflammation, and have anti-apoptotic and pro-angiogenic effects, making them an ideal therapeutic strategy to target chronic inflammation and intestinal damage in IBD. In recent years, hematopoietic stem cells (HSCs) and adult mesenchymal stem cells (MSCs) have shown efficacy in treating IBD. In addition, numerous clinical trials have evaluated the efficiency of MSCs in treating the disease. This review summarizes the current research progress on the safety and efficacy of SC-based therapy for IBD in both preclinical models and clinical trials. We discuss potential mechanisms of SC therapy, including tissue repair, paracrine effects, and the promotion of angiogenesis, immune regulation, and anti-inflammatory effects. We also summarize current SC engineering strategies aimed at enhancing the immunosuppressive and regenerative capabilities of SCs for treating intestinal diseases. Additionally, we highlight current limitations and future perspectives of SC-related therapy for IBD.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Intestinal stem cell aging at single-cell resolution: Transcriptional perturbations alter cell developmental trajectory reversed by gerotherapeutics

The intestinal epithelium consists of cells derived from continuously cycling Lgr5hi intestinal stem cells (Lgr5hi ISCs) that mature developmentally in an ordered fashion as the cells progress along the crypt-luminal axis. Perturbed function of Lgr5hi ISCs with aging is documented, but the consequent impact on overall mucosal homeostasis has not been defined. Using single-cell RNA sequencing, the progressive maturation of progeny was dissected in the mouse intestine, which revealed that transcriptional reprogramming with aging in Lgr5hi ISCs retarded the maturation of cells in their progression along the crypt-luminal axis. Importantly, treatment with metformin or rapamycin at a late stage of mouse lifespan reversed the effects of aging on the function of Lgr5hi ISCs and subsequent maturation of progenitors. The effects of metformin and rapamycin overlapped in reversing changes of transcriptional profiles but were also complementary, with metformin more efficient than rapamycin in correcting the developmental trajectory. Therefore, our data identify novel effects of aging on stem cells and the maturation of their daughter cells contributing to the decline of epithelial regeneration and the correction by geroprotectors.

The antioxidant effects of hedysarum polybotrys polysaccharide in extending lifespan and ameliorating aging-related diseases in Drosophila melanogaster

Hedysarum polybotrys polysaccharide (HPS) is one of the main active ingredients of Hedysarum with many health-beneficial properties, including antioxidant property, immunomodulatory, anti-inflammatory, and anti-tumor. However, the effect of HPS on anti-aging is still unclear. This study was to explore the protective function of HPS on aging and age-related diseases using Drosophila melanogaster. The results demonstrated that HPS supplementation promoted hatchability and prolonged lifespan by enhancing the antioxidative capacity. Administraction of HPS ameliorated age-related symptoms such as imbalanced intestinal homeostasis, sleep disturbances, and beta-amyloid (Aβ) induced Alzheimer's disease (AD) in flies, but did not modulate neurobehavioral deficits in the AD model of tauopathy and the Parkinson's disease (PD) model of Pink1 mutation. Overall, this study reveals that HPS has strong potential in the prevention of aging and age-related diseases, and provided a new candidate for the development of anti-aging drugs.

Fall of PARP3 restrains Lgr5+ intestinal stem cells proliferation and mucosal renovation in intestinal aging

The regeneration ability of intestinal epithelium is degenerated in aging. The determining factor is leucine-rich repeat-containing G-protein-coupled receptor 5-positive intestinal stem cells (Lgr5⁺ ISCs). Lgr5-EGFP (enhanced green fluorescence protein) knock-in in transgenic mice at three different ages (young group: 3-6 months; middle group: 12-14 months; old group: 22-24 months) were used to examined Lgr5⁺ ISCs at three different timepoints. The jejunum samples were collected for histology, immunofluorescence analysis, western blotting and PCR. In tissue, crypt depth, proliferating cells and Lgr5⁺ ISC numbers were increased in the middle group (12-14 months) and decreased in the old group (22-24 months). The number of proliferating Lgr5⁺ ISCs gradually decreased as the mice aged. In organoids, the budding number, projected area, and Lgr5⁺ ISC ratio decreased as the mice aged. The gene expression of poly (ADP-ribose) polymerase 3 (Parp3) and the protein expression of PARP3 were increased in the middle- and old-aged groups. PARP3 inhibitors slowed organoid growth in the middle group. In conclusion, PARP3 is upregulated in aging, and the inhibition of PARP3 reduces the proliferation of aging Lgr5⁺ ISCs.

Paneth cells as the cornerstones of intestinal and organismal health: a primer

Paneth cells are versatile secretory cells located in the crypts of Lieberkühn of the small intestine. In normal conditions, they function as the cornerstones of intestinal health by preserving homeostasis. They perform this function by providing niche factors to the intestinal stem cell compartment, regulating the composition of the microbiome through the production and secretion of antimicrobial peptides, performing phagocytosis and efferocytosis, taking up heavy metals, and preserving barrier integrity. Disturbances in one or more of these functions can lead to intestinal as well as systemic inflammatory and infectious diseases. This review discusses the multiple functions of Paneth cells, and the mechanisms and consequences of Paneth cell dysfunction. It also provides an overview of the tools available for studying Paneth cells.

The impact of aging on intestinal mucosal immune function and clinical applications

Immune cells and immune molecules in the intestinal mucosa participate in innate and adaptive immunity to maintain local and systematic homeostasis. With aging, intestinal mucosal immune dysfunction will promote the emergence of age-associated diseases. Although there have been a number of studies on the impact of aging on systemic immunity, relatively fewer studies have been conducted on the impact of aging on the intestinal mucosal immune system. In this review, we will briefly introduce the impact of aging on the intestinal mucosal barrier, the impact of aging on intestinal immune cells as well as immune molecules, and the process of interaction between intestinal mucosal immunity and gut microbiota during aging. After that we will discuss potential strategies to slow down intestinal aging in the elderly.

In-depth analysis of the relationship between bovine intestinal organoids and enteroids based on morphology and transcriptome

Intestinal organoids and enteroids as excellent models are miniaturized and simplified for studying intestinal physiological and pathological functions, drug screening, and regenerative medicine. Recently, the application demands for organoids and enteroids in organ development and nutrition metabolism, immune and cancer research increased. But there are few comparative studies on both of them, especially in immunity and metabolism, which is also conducive to further clarifying the role of crypt stem cells and stromal cells. In our study, "natural" organoids were obtained by tissue culture from fetal bovine jejunum and enteroids were successfully isolated and cultured from organoids without supplementing exogenous factors and Matrigel. These mini-guts displayed similar features to the intestine through immunohistochemistry and transmission electron microscopy. Organoid and enteroid were systematically compared based on the transcriptome. And some of the results were verified by qRT-PCR. Our results showed KDGs (Key driver genes) (e.g., SLC13A1, HOXA7, HOXA6, HOXA5, and HOXD4) of organoids enriched in signaling pathways related to organ development and morphology and metabolism. KDGs (e.g., IL-6, PTGS2, CDH1, JUN, and EGFR) of enteroid were involved in cancer, MAPK, and immune-related signaling pathways. To the Wnt signaling pathway, highly expressed genes in organoids, including RSPO2, NOTUM, WNT6, and RSPO3, supported the homeostasis of crypt stem cells. Enteroids highly expressed CTNNB1 and WNTs. In addition, we found that organoids and enteroids carried out different functions in immunity and metabolism due to different cell compositions. Therefore, it suggested organoid is more compatible and comprehensive, and enteroid is qualified for the research of immunity and cancer.

Transplanted hair follicle mesenchymal stem cells alleviated small intestinal ischemia–reperfusion injury via intrinsic and paracrine mechanisms in a rat model

Background: Small intestinal ischemia-reperfusion (IR) injury is a common intestinal disease with high morbidity and mortality. Mesenchymal stem cells (MSCs) have been increasingly used in various intestinal diseases. This study aimed to evaluate the therapeutic effect of hair follicle MSCs (HFMSCs) on small intestinal IR injury.

Methods: We divided Sprague–Dawley rats into three groups: the sham group, IR group and IR + HFMSCs group. A small intestinal IR injury rat model was established by clamping of the superior mesenteric artery (SMA) for 30 min and reperfusion for 2 h. HFMSCs were cultured in vitro and injected into the rats through the tail vein. Seven days after treatment, the intrinsic homing and differentiation characteristics of the HFMSCs were observed by immunofluorescence and immunohistochemical staining, and the paracrine mechanism of HFMSCs was assessed by Western blotting and enzyme-linked immunosorbent assay (ELISA).

Results: A small intestinal IR injury model was successfully established. HFMSCs could home to damaged sites, express proliferating cell nuclear antigen (PCNA) and intestinal stem cell (ISC) markers, and promote small intestinal ISC marker expression. The expression levels of angiopoietin-1 (ANG1), vascular endothelial growth factor (VEGF) and insulin growth factor-1 (IGF1) in the IR + HFMSCs group were higher than those in the IR group. HFMSCs could prevent IR-induced apoptosis by increasing B-cell lymphoma-2 (Bcl-2) expression and decreasing Bcl-2 homologous antagonist/killer (Bax) expression. Oxidative stress level detection showed that the malondialdehyde (MDA) content was decreased, while the superoxide dismutase (SOD) content was increased in the IR + HFMSCs group compared to the IR group. An elevated diamine oxidase (DAO) level reflected the potential protective effect of HFMSCs on the intestinal mucosal barrier.

Conclusion: HFMSCs are beneficial to alleviate small intestinal IR injury through intrinsic homing to the small intestine and by differentiating into ISCs, via a paracrine mechanism to promote angiogenesis, reduce apoptosis, regulate the oxidative stress response, and protect intestinal mucosal function potentially. Therefore, this study suggests that HFMSCs serve as a new option for the treatment of small intestinal IR injury.

Lack of evidence for increased transcriptional noise in aged tissues

Aging is often associated with a loss of cell type identity that results in an increase in transcriptional noise in aged tissues. If this phenomenon reflects a fundamental property of aging remains an open question. Transcriptional changes at the cellular level are best detected by single-cell RNA sequencing (scRNAseq). However, the diverse computational methods used for the quantification of age-related loss of cellular identity have prevented reaching meaningful conclusions by direct comparison of existing scRNAseq datasets. To address these issues we created Decibel, a Python toolkit that implements side-to-side four commonly used methods for the quantification of age-related transcriptional noise in scRNAseq data. Additionally, we developed Scallop, a novel computational method for the quantification of membership of single cells to their assigned cell type cluster. Cells with a greater Scallop membership score are transcriptionally more stable. Application of these computational tools to seven aging datasets showed large variability between tissues and datasets, suggesting that increased transcriptional noise is not a universal hallmark of aging. To understand the source of apparent loss of cell type identity associated with aging, we analyzed cell type-specific changes in transcriptional noise and the changes in cell type composition of the mammalian lung. No robust pattern of cell type-specific transcriptional noise alteration was found across aging lung datasets. In contrast, age-associated changes in cell type composition of the lung were consistently found, particularly of immune cells. These results suggest that claims of increased transcriptional noise of aged tissues should be reformulated.