The microbiota-gut-brain (MGB) axis is a dynamic network connecting gut microorganisms and the brain through various signaling pathways, playing a crucial role in the diagnosis and treatment of complex neurological disorders. Bile acids (BAs), synthesized in the liver and transformed by the gut microbiota, are known to modulate gastric inflammation. However, their potential roles within the MGB axis and their impact on neuroinflammation and neurological disorders have not yet been investigated. Deoxycholic acid (DCA) and cholic acid (CA), which are secondary and primary BAs, respectively, were treated to microglial BV-2 cells to find out alteration in the signaling pathway. DCA and CA were administered to healthy mice to examine their effect on neurological function. Clostridium scindens, which converts CA into DCA in the gut, was administered to mice to investigate the potential contribution of gut microbial conversion of CA to DCA to neurological outcomes. Levels of BA-converting bacteria and enzyme were analyzed in human fecal samples. First, we observed that DCA elicited stronger pro-inflammatory response than CA in BV-2 microglial cells and increased NLRP3-associated inflammasome signaling. These responses were attenuated by pharmacological inhibition of FXR and S1PR2, with reduced MAPK/NF-κB and NLRP3-associated signaling. Then, DCA was orally administered to normal mice, and it was found that increased DCA concentration increased glial activation and activated microglial NLRP3-associated signaling in the brain. In addition, DCA administration induced memory impairment and altered the AKT/ERK/CREB/BDNF signaling pathway. The concentration of DCA in the hippocampus of mice was significantly correlated with the fear memory score and neuroinflammatory markers. Co-administration of CA and C. scindens was associated with alterations in memory-related behavioral outcomes. In human-derived samples, we observed that the levels of BA-converting bacteria, including C. scindens, and related enzymes were increased in the feces of patients with mild cognitive impairment. These results demonstrate that DCA promotes NLRP3-associated neuroinflammatory responses and neuronal dysfunction, potentially involving FXR- and S1PR2-related signaling pathways. These findings suggest that elevated DCA exposure may contribute to gut–brain axis dysfunction and cognitive impairment under experimental conditions.
Impaired cutaneous wound healing is a major clinical burden, particularly among older individuals and patients with diabetes. Lysophosphatidic acid (LPA) is a bioactive phospholipid with known roles in cell proliferation, migration, and vascular formation; however, its mechanistic contribution in wound repair has not been systematically characterized. Therefore, this study aimed to determine whether topical LPA accelerates wound closure in a murine full-thickness excisional wound model and to elucidate the underlying cellular and molecular mechanisms. Full-thickness excisional wounds were created on the dorsal skin of mice, and LPA or vehicle was applied once daily. Wound closure was assessed over 13 days using digital planimetry. Bulk RNA sequencing, quantitative reverse transcription polymerase chain reaction, immunofluorescence, flow cytometry, vascular permeability, and tissue hypoxia assays were employed to delineate the underlying mechanisms. Published single-cell RNA sequencing data from mouse skin were re-analyzed to map LPA receptor expression. Topical LPA accelerated the closure of full-thickness excisional skin wounds. Transcriptomic analysis identified upregulation of gene programs associated with vasculature development and extracellular matrix organization. LPA markedly increased endothelial cell numbers and vessel density. Critically, the vessels formed in LPA-treated wounds subsequently displayed elevated pericyte coverage, reduced permeability, and decreased tissue hypoxia, indicating functional vascular maturation. Concurrently, fibroblast-associated matrix genes were upregulated, collagen deposition was accelerated, and lymphangiogenesis was promoted at the wound site. Single-cell analysis implicated LPAR1 in fibroblasts and LPAR4/LPAR6 in endothelial cells as candidate mediators of these effects. LPA promotes both vascular maturation and fibroblast activation during wound repair, distinguishing it from classical pro-angiogenic factors. These findings establish LPA as a mechanistically distinct therapeutic candidate and suggest a novel approach for targeting vascular maturation in cutaneous wound care.
Ischemia-reperfusion (IR) injury is a complex process that comprises the restoration of oxygen flow after deprivation, which exacerbates cellular damage. Among the molecular regulators involved, cyclophilins (Cyps) have emerged as critical mediators of oxidative stress, mitochondrial dysfunction, and associated inflammation, highlighting them as promising targets. In this context, natural compounds represent an important source of bioactive molecules. The protective effects of seven previously described diterpenes (1–7), purified from two brown seaweed species of the genus Dictyota, were evaluated in a microglial IR model. Compounds were purified by preparative chromatography and identified by nuclear magnetic resonance spectroscopy and mass spectrometry. BV2 microglial cells were incubated with compounds under oxygen–glucose deprivation conditions followed by reperfusion. Cyclosporine A (CsA) was used as positive control in all assays. Cell viability, reactive oxygen species (ROS) levels and mitochondrial membrane potential (∆Ψm) were analyzed. Cyps binding interactions were studied using a surface plasmon resonance biosensor. Cyps expression and activation of HIF1α and Nrf2 pathways were evaluated by western blot, and IL-1β secretion was quantified by ELISA. Dictyota metabolites were as potent as CsA in reducing ischemia impact. When cells were reperfused, 1–7 counteracted the damage, with compounds 4 and 5 showing the strongest effects. Treatment with 1–7 also reduced ROS levels and restored ∆Ψm, indicating antioxidant and mitochondrial protective properties. Subsequently, their ability to bind Cyps was assessed, and 4, 5, and 7 displayed high affinity with equilibrium dissociation constants in the micromolar range. Therefore, the effect of metabolites on Cyps expression was analyzed. Notably, 1–7 downregulated Cyps A and D as efficiently as CsA. Interestingly, compounds modulated the activation of HIF1α and Nrf2, proteins involved in hypoxia adaptation and redox homeostasis, while CsA was ineffective. Compound 1 increased the nuclear translocation of both proteins, 3, 6, and 7 enhanced HIF1α activation, and 2 increased Nrf2 nuclear translocation. Moreover, compounds 1–7 decreased the secretion of IL-1β. This study identifies diterpenes from Dictyota spp. as promising protective agents against oxygen–glucose deprivation/reperfusion injury through the modulation of Cyps and stress-response pathways with better outcomes than CsA.
Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovial inflammation, cartilage degradation, and bone erosion. Fibroblast-like synoviocytes (FLS) play a central role in perpetuating joint damage, yet current therapies inadequately address FLS-driven pathology. Existing preclinical models, including murine collagen-induced arthritis and conventional in vitro cultures, lack the complexity to fully recapitulate human disease mechanisms. Here, we describe the development of a three-dimensional (3D) RA bone–cartilage interface (BCI) organoid that integrates primary human mesenchymal stem cell-derived osteoblasts, peripheral blood mononuclear cell-derived osteoclasts and lymphocytes, immortalized human chondrocyte spheroids, and the RA synovial fibroblast cell line SW982. Exposure to TNF-α, IL-1β, and TGF-β induced pro-inflammatory cytokines, matrix-degrading enzymes, and increased fibrotic gene expression, accompanied by histological and microCT evidence of bone dysregulation. Therapeutic testing showed that methotrexate, etanercept, and tofacitinib reduced cytokine production and pro-inflammatory gene expression but had limited impact on profibrotic gene expression. This modular, human-derived RA BCI organoid reproduced key features of RA pathogenesis that can enable direct assessment of therapeutic mechanisms at the bone–cartilage–synovial interface. The RA BCI organoid provides a physiologically relevant, scalable platform for preclinical drug discovery and for identifying combination strategies that address both the inflammatory and fibrotic components of RA pathology.
Osteoarthritis (OA) is a common age-related joint disease characterized by cartilage loss and synovitis. Cellular senescence contributes to chronic inflammation through senescence-associated secretory phenotypes (SASPs). Recent evidence indicates that senescent synovial fibroblasts (SFs) contribute to OA pathogenesis. However, the in vitro modeling of the microenvironment formed by senescent SFs via SASPs remains limited. Here, we developed a three-dimensional (3D) senescent synovial organoid model using senescent rat SFs. We created the senescent SFs by treating normal rat SFs in monolayer culture with hydrogen peroxide (H2O2). Senescence induction was confirmed by senescence-associated beta-galactosidase (SA-β-gal) staining, γH2AX expression, and transcriptomic analysis. Synovial organoids were then generated by embedding normal or senescent SFs in Matrigel. Transcriptomic and protein–protein interaction analyses were performed and the expression of key regulatory factors was evaluated by immunostaining. Transcriptomic profiles of the organoids were further compared with bulk RNA sequencing data from rat OA synovium and single-cell RNA sequencing data from human OA synovium. Rat chondrocytes and RAW264.7 cells were co-cultured with control or senescent organoids. H2O2 treatment significantly increased SA-β-gal positivity and the expression of γH2AX and senescence-associated genes in monolayer-cultured SFs. Senescent organoids had thickened lining layers and distinct transcriptomic profiles compared to normal organoids. Enrichment analyses identified the upregulation of genes associated with extracellular matrix (ECM) organization, growth factor responses, and PI3K-Akt/MAPK signaling. Senescent organoids had a unique secretory phenotype characterized by elevated expression of ECM components, ECM-degrading enzymes, and proinflammatory factors. The expression of senescence-associated genes was greater in senescent organoids than in control organoids or H2O2-treated monolayer SFs. Protein–protein interaction analysis of senescent organoids identified central hub genes, including Il6, Tgfb1, Mmp13, and Ngf, with upregulation also confirmed at the protein level. Comparison with transcriptomic data from rat and human OA synovium revealed transcriptional similarities between senescent organoids and OA SFs in both species. Co-culture assays showed that senescent organoids decreased Sox9 expression and increased Col10a1 expression in chondrocytes, whereas they increased Cd80 expression and decreased Cd206 expression in RAW264.7 cells. Senescent organoids can faithfully recapitulate key features of the senescent SF microenvironment, offering an ideal platform for cellular senescence-based OA research.
Rheumatoid arthritis (RA) involves multiple pro-inflammatory cytokines; fibroblast-like synoviocytes (FLS) are central effector cells that integrate these signals to produce pathogenic mediators. Tumor necrosis factor (TNF) is a major upstream driver of coordinated inflammatory mediator induction in FLS; however, the underlying mechanisms remain incompletely defined, particularly intracellular feed-forward amplification sustaining and enhancing TNF-driven transcriptional outputs. Complement factor H (FH; gene CFH), a Sushi domain-only complement regulator, is elevated in RA serum. FH is regarded as an extracellular inhibitor of complement activation; however, its potential intracellular expression and functions in FLS have not been explored. We aimed to investigate intracellular FH expression and function using an in vitro transcribed messenger RNA (IVT mRNA)-based approach. FH expression in sera, synovial tissues, and fibroblast-like synoviocytes (FLS) were assessed by enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, RT-qPCR, and immunoblotting. To examine intracellular FH function, FLS were transfected with CFH-encoding IVT mRNA to express FH intracellularly, followed by next-generation sequencing (RNA-seq), RT-qPCR, ELISA, phosphorylation assays, and pathway inhibition. Interactions between TNF-driven signaling and intracellular FH were evaluated using TNF- and/or FH-neutralizing antibodies, with or without CFH-targeting small interfering RNA (siRNA). FH was highly expressed in RA synovium and predominantly localized intracellularly in FLS. To assess intracellular FH function, FLS were transfected with CFH-encoding IVT mRNA, which induced the coordinated upregulation of RA-relevant mediators, including granulocyte–macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-8, IL-6, and multiple chemokines. Mechanistically, intracellular FH activated nuclear factor-κB (NF-κB) signaling, promoting receptor-interacting serine/threonine-protein kinase 2 (RIPK2) phosphorylation and p65 nuclear translocation, and the competitive nucleotide-binding oligomerization domain 2 (NOD2) antagonist suppressed FH-driven gene induction. TNF and intracellular FH additively enhanced pathogenic mediator production. CFH-targeting siRNA attenuated TNF-induced cytokine and chemokine expression; blockade of extracellular FH had no detectable effect. Combined TNF neutralization and CFH knockdown produced more effective suppression of cytokine induction than either intervention alone. Intracellular FH is a previously unrecognized amplifier of TNF-driven inflammation in RA-FLS via a NOD2/RIPK2/NF-κB axis, establishing a feed-forward loop boosting pathogenic mediator production. Dual targeting of TNF and intracellular FH may represent a therapeutic strategy to suppress synovial inflammation more effectively.
Abstract Background In humans, large skin defects require tissue transplantation because adult skin lacks full regenerative capacity. However, allogeneic grafts are typically rejected due to strong immune responses, whereas autologous grafts often result in severe fibrosis and permanent scarring. In contrast, regenerative vertebrates such as newts can restore tissues with minimal scarring, suggesting the presence of distinct mechanisms regulating tissue repair. How such organisms respond to immune activation induced by non-self tissue transplantation remains unclear. In this study, we aimed to determine how adult newts respond to allogeneic skin transplantation and to examine whether fibrosis induced under such conditions is sustained or resolved. Methods We established an allogeneic skin graft model in adult Japanese fire-bellied newts and compared it with autologous grafting. Graft fate, tissue morphology, fibrosis, and immune cell dynamics were analyzed histologically over time. To assess the contribution of macrophage-lineage cells, animals were treated with clodronate liposomes prior to transplantation. Results In contrast to mammals, allogeneic grafts did not exhibit typical features of acute rejection and did not show apparent graft loss. Following transplantation, grafts exhibited a characteristic sequence of changes: initial vascular integration, subsequent loss of detectable perfusion, and progressive remodeling of graft appearance. At the donor–host interface, a distinct collagen-rich fibrotic tissue formed, accompanied by marked leukocyte infiltration. This tissue appeared at 2 weeks, reached maximal thickness at 4 weeks, and regressed by 8 weeks. During this period, the graft surface gradually acquired host-like pigmentation, while structural elements of donor tissue remained detectable histologically. Iba1-positive macrophage-lineage cells accumulated within the graft during the fibrotic phase and decreased as the tissue regressed. Depletion of these cells did not prevent fibrosis formation but delayed its regression and prolonged graft thickening. Conclusions Allogeneic skin transplantation in adult newts induces a distinct response in which non-self tissue is not completely lost and a collagen-rich fibrotic tissue forms transiently and subsequently undergoes resolution. These findings suggest that fibrosis induced under non-self immune activation is not necessarily a terminal state but may represent a dynamically regulated process capable of resolution.
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the emergence of autoantibodies and deposition of immune complexes. SLE presents with heterogeneous multi-organ involvement that varies among patients and its mechanisms have been investigated to facilitate appropriate stratification and treatment selection. Bulk RNA-seq and bulk ATAC-seq have provided important insights into the pathogenesis of SLE; however, these approaches are inherently limited by their reliance on predefined cell subsets and known markers, which can introduce bias and restrict their ability to fully resolve cellular heterogeneity. Recent advances in multi-omics analyses have enabled the investigation of multi-layered information beyond single-cell RNA sequencing (scRNA-seq) alone and have contributed substantially to elucidating the pathogenesis of SLE. Although the emergence of autoreactive B cells and the production of autoantibodies in SLE are well established, the mechanisms of evasion from negative selection remain unclear. Multi-omics analyses have revealed key aspects of SLE pathogenesis, particularly the expansion of atypical B cells (ABCs), an autoreactive population driven by extrafollicular pathways. Furthermore, beyond transcriptional profiling, multi-omics analysis has emerged as an additional investigative method, which combines scRNA-seq with other modalities. Spatial analyses, for instance, have provided critical insights into the tissue localization and persistence of autoreactive B cells within inflammatory niches in lupus nephritis, suggesting that local microenvironments contribute to treatment resistance. Additionally, B cell receptor (BCR) sequencing has revealed distinctive BCR features in SLE, such as reduced somatic hypermutation, increased repertoire naiveness, and increased immunoglobulin variable region heavy chain gene (IGHV4-34) usage in B cells in bone marrow and affected organs (not only in peripheral blood). Furthermore, emerging multimodal approaches integrating spatial, transcriptomic, and epigenomic information further highlight pathogenic cell–cell interactions and inflammatory circuits that cannot be captured by scRNA-seq alone. In this review, we summarize recent multi-omics studies that elucidate the origin, differentiation, and tissue localization of pathogenic B cells in SLE. We provide an overview of the multi-omics analyses focusing on B cells so far, especially at single-cell resolution, and discuss their possible applications in precision medicine.
BACKGROUND:Macrophage lipid accumulation is a hallmark of atherosclerosis and other metabolic diseases. Toll-like receptor 4 (TLR4) signaling and cytoskeletal remodeling have each been implicated in this process, yet the mechanistic connections among these three elements remain incompletely defined. MAIN BODY:This review synthesizes current evidence for pathways in which TLR4 activation, via bifurcated signaling through MyD88/TRAM, SYK/Src, and integrins, engages small GTPases (Rac, Cdc42, Rho) and downstream effectors including cofilin and paxillin to drive cytoskeletal remodeling. These cytoskeletal changes facilitate lipid internalization through multiple routes, including macropinocytosis, receptor redistribution, and lysosomal synapse formation, and regulate lipid droplet dynamics, ultimately promoting foam cell formation. We also discuss the therapeutic potential and safety challenges of targeting cytoskeletal regulators in diseases such as atherosclerosis. SHORT CONCLUSION:The convergence of TLR4 signaling, cytoskeletal remodeling, and lipid metabolism represents a compelling mechanistic nexus for understanding foam cell formation. Elucidating the molecular details of this pathway-particularly the SYK/Src-cytoskeleton axis-may reveal macrophage-selective therapeutic targets that suppress pathological lipid accumulation while preserving host defense functions.
Mesenchymal stromal cells (MSCs) possess therapeutic potential largely reliant on intact mitochondrial function to maintain reparative function. However, obesity compromises MSC metabolism and reparative capacity. MOTS-c, a mitochondria-derived peptide, is known to regulate cellular metabolism, but its role in human MSC biology remains unclear. We hypothesized that restoring MOTS-c signaling rescues the impaired functionality of adipose-derived MSCs from individuals with obesity. MSCs isolated from abdominal fat of patients with obesity (BMI ≥ 30 kg/m2) and lean donors (BMI < 30 kg/m2) (n = 6/group) were assessed in vitro for changes in proliferation, senescence (p16, p21) TNF-α, and antioxidant gene expression following MOTS-c co-incubation. In vivo, the effects of MOTS-c pre-treatment on the reparative capacity of obese MSC were tested in stenotic mouse kidneys. Basal MOTS-c expression was lower in obese vs. lean MSCs. Nevertheless, although exogenous MOTS-c restored intracellular levels and activated AMPK signaling in obese MSCs, it reduced proliferation, increased expression of senescence-associated genes (p16, p21), and upregulated TNF-α. In vivo, in a murine model of renal artery stenosis, MOTS-c-pretreated MSCs failed to improve renal perfusion, fibrosis, or tubular injury, while pretreatment also blunted the reparative efficacy of lean MSCs. These findings reveal that restoration of mitochondrial metabolic signaling is insufficient to reverse obesity-induced MSC dysfunction and may paradoxically exacerbate senescence and inflammation. These results suggest a dissociation between metabolic activation and functional stemness, underscoring context-dependent effects of mitochondrial-derived peptides in MSC biology.
Cartilage is an avascular and aneural connective tissue vital for joint function, yet its limited intrinsic regenerative capacity poses significant challenges for treating injuries and degenerative diseases such as osteoarthritis (OA). Conventional models—including animal studies, cell lines, and primary chondrocyte cultures—exhibit considerable limitations in accurately replicating the native cartilage microenvironment, species-specific relevance, and differentiation potential. Recently, cartilage organoids have emerged as transformative tools that closely emulate the architecture, cellular heterogeneity, and extracellular matrix (ECM) properties of native cartilage, thereby offering a physiologically relevant platform for investigation. This review systematically examines the mechanisms governing chondrogenesis, including chondrocyte differentiation and matrix synthesis, as well as the construction of cartilage disease models. We focus on recent advances in cartilage organoid research, covering cultivation techniques, structural and functional characteristics, and diverse characterization methodologies. Furthermore, we highlight their applications in simulating pathological features of cartilage diseases, drug screening, toxicity testing, and gene therapy exploration. Current technological limitations—such as challenges in vascularization and mechanical strength—are discussed, together with future directions for developing multifunctional organoids and associated ethical and clinical considerations. This review aims to provide insights into the translational potential of cartilage organoids in regenerative medicine and disease modeling.
The striatum plays a central role in motor control, cognition, reward processing, and habit formation, and its dysfunction is implicated in a broad spectrum of neurological and psychiatric disorders. Although animal models have provided important insights into striatal development and disease mechanisms, species-specific differences in cellular composition, developmental timing, and circuit organization limit their translational relevance to the human brain. In this context, human pluripotent stem cells (PSCs), including embryonic stem cells and induced pluripotent stem cells, have emerged as valuable platforms for modeling human striatal development and pathology in vitro. In this review, we summarize current approaches for generating striatal cell types from PSCs, with a particular focus on medium spiny neurons (MSNs), the principal projection neurons of the striatum. We discuss key developmental principles underlying dorsal and ventral striatal specification and highlight the protracted maturation of human MSNs, which may contribute to human-specific disease vulnerability. Advances in differentiation strategies, including small molecule-based patterning, transcription factor-driven induction, and three-dimensional organoid and assembloid systems, have progressively improved the efficiency, reproducibility, and cellular complexity of PSC-derived striatal models. We further review applications of PSC-derived striatal systems in disease modeling, noting that most studies to date have focused on Huntington’s disease, where these models have revealed early developmental, transcriptional, synaptic, and network-level abnormalities. More recent studies have begun to extend these approaches to other neurological conditions and to incorporate circuit-level analyses using cortico-striatal assembloids. In parallel, the growing availability of single-cell and single-nucleus transcriptomic datasets from the human striatum provides powerful reference frameworks for benchmarking the identity and maturation state of PSC-derived striatal cells. Finally, we discuss current challenges and limitations of PSC-based striatal models, including incomplete maturation, limited representation of non-neuronal cell types, and restricted applicability to psychiatric disorders. We propose that continued integration of developmental biology, public multi-omics resources, and advanced in vitro modeling strategies will be essential for advancing human striatal models and expanding their utility in translational neuroscience.
Disease models are used to evaluate drug candidates, and compounds that are highly effective in vivo models have traditionally been prioritized for development. While conventional ‘gold standard’ animal models have been central to autoimmune drug discovery, there is increasing recognition that addressing unmet medical needs requires models capable of capturing patient pathophysiology beyond the scope of these classical systems. Accordingly, models that reflect human disease mechanisms not reproducible in conventional animals are becoming increasingly important. Humanized mice are immunodeficient mice transplanted with human immune cells, hepatocytes, thymic tissue, and other components to create a human-like biological environment that cannot be replicated in wild-type mice. Research on humanized mice has advanced through efforts to reconstitute a diverse human immune system in mice, together with accumulating knowledge of patient-specific factors such as autoantibodies and autoreactive T cells. Additionally, single-cell analyses and human tissue studies are underway to recreate the human-specific disease phenomena in humanized mice. In this review, immune-system-humanized mice are used to provide a comprehensive overview of recent advances in immune-system-humanized mouse technologies, their applications to immune-related disease models, and their current utilization in drug discovery research.
T cell exhaustion remains a critical barrier in treating chronic infections and cancer. To overcome this, our laboratory has established a platform for generating “rejuvenated” T cells from induced pluripotent stem cells (iPSCs). This review outlines our research trajectory, transitioning from the foundational autologous “T-iPSC” concept to scalable, “off-the-shelf” allogeneic strategies. We detail the establishment of clinical-grade, xeno-free manufacturing protocols and the integration of advanced gene editing—including functional enhancement through intracellular signaling modulation, immune rejection–related gene editing to minimize immunogenicity, and optimization of synthetic receptor architectures to mitigate the risk of Graft-versus-Host Disease (GvHD) while enhancing targeting efficiency. Furthermore, we describe our activity on generating regulatory T cells from iPSC for managing autoimmune disorders and GvHD. Finally, we discuss the remaining challenges and the future roadmap for translating these therapeutic T cells into clinical practice.
Senescence of T cells is strongly linked to organismal aging through two interconnected processes: chronic low-grade inflammation and reduced immune surveillance of senescent cells. T cells are particularly vulnerable to thymic involution, hematopoietic stem cell aging, repeated homeostatic proliferation, chronic antigenic stimulation, and metabolic and mitochondrial dysfunction. As a result, aged T cells may lose their capacity to combat infection and eliminate senescent cells, while also contributing to inflammaging through the production of inflammatory cytokines. Recent preclinical studies in murine models have demonstrated that modulation of T-cell immunosenescence can ameliorate age-related diseases. These approaches include PD-1/PD-L1 blockade, senolytic chimeric antigen receptor T (CAR-T) cells, and CXCL4/platelet factor 4 (PF4). In addition, early-stage human clinical studies of caloric restriction, low-dose mTOR inhibition, thymic regeneration, and mesenchymal stromal/stem cell (MSC) therapy suggest that interventions targeting immunosenescence may provide health benefits. Moreover, in murine models of Alzheimer’s disease, T cells infiltrating the brain may exert either disease-promoting or protective effects depending on the disease stage, highlighting an important point of intersection between T-cell-mediated immunosenescence and brain aging. This review summarizes the basic concepts of immunosenescence, the molecular basis of immune surveillance of senescent cells, age-associated T-cell subsets, their links to brain aging, and interventional strategies aimed at clinical translation, with particular emphasis on T-cell biology and the transcriptional regulatory network driven by NR4a.
BACKGROUND:Definitive hematopoietic stem cells (HSCs) emerge within intra-aortic hematopoietic cell clusters (IAHCs) located in the dorsal aorta of the aorta-gonad-mesonephros (AGM) region during midgestation in the mouse embryo. Thereafter, HSCs migrate to the fetal liver (FL) and finally settle in the bone marrow (BM). We previously showed that the transcription factor Sox17 is expressed in IAHCs. Overexpression of the Sox17 gene in IAHC cells induces the formation of cell clusters in vitro that resemble IAHCs and retain hematopoietic potential. In addition, a previous report showed that Sox17-transduced hematopoietic stem/progenitor cells (HSPCs) in the BM maintained multipotency. However, whether the ability to form such cell clusters differs among hematopoietic sites has not been fully examined. METHODS:We examined whether viral overexpression of the Sox17 gene in HSPCs derived from the AGM region, the FL, and the BM leads to the formation of cell clusters. To identify the candidate genes involved in cluster formation, we performed RNA sequencing (RNA-seq) analysis on Sox17-ERT-transduced cells from the AGM region and the BM cultured with or without tamoxifen. We further analyzed the ability of one candidate gene, the Procr gene, to support cluster formation and in vitro hematopoietic activity. RESULTS:A large number of multilineage colonies were observed in Sox17-ERT-transduced tamoxifen-treated cells in all tissues examined. However, BM cells generated significantly fewer clusters than embryonic tissues under identical experimental conditions. RNA-seq analysis revealed several genes that were highly expressed in Sox17-ERT-transduced tamoxifen-treated cells from the AGM region. The Procr gene, one of these genes, was expressed in IAHCs and was found to contribute to cluster formation and to be associated with the maintenance of in vitro hematopoietic activity in Sox17-transduced cells of the AGM region. CONCLUSIONS:Our results revealed that the efficiency of cluster formation varies depending on the developmental origin of hematopoietic cells, suggesting that cluster formation and colony-forming activity can be partially dissociated during the transition from fetal to adult hematopoiesis. Moreover, the Procr gene appears to contribute to cluster formation and to be associated with enhanced in vitro hematopoietic activity in midgestation mouse embryos.
Muscular dystrophies (MDs) are a set of neuromuscular diseases characterized by progressive muscle weakness and wasting. Their pathophysiology entails several aberrant genetic pathways including the perturbation of microRNA (miRNA) and other non-coding RNA (ncRNA) levels and functions, and the subsequent dysregulation of their downstream targets. In healthy tissue, ncRNAs exert their influence by fine-tuning physiological mechanisms. However, in dystrophic conditions, these ncRNAs become involved in modulation of pathological mechanisms. The main pathomechanism themes that involve ncRNAs and proteins in MD are myogenesis insufficiency, structural instability, destructive pathways, and signaling failure. This review attempts to delineate all the major contributory ncRNAs, particularly miRNAs, as well as their associated proteins involved in disease initiation, maintenance, and outcomes across the spectrum of MD subtypes.
Abstract Background Aging alters the systemic steroid environment, including reductions in circulating androgens. In peripheral tissues, androgen exposure is regulated mainly by local steroid metabolism, which can activate or inactivate androgens independently of systemic concentrations. In the scalp, 5α-reductase–mediated generation of dihydrotestosterone (DHT) has been studied extensively in relation to conditions such as androgenetic alopecia. In contrast, age-related regulation of DHT-inactivating pathways, including the aldo–keto reductase family 1 member C (AKR1C) family, remains insufficiently defined. Methods We examined AKR1C1–4 expression in scalp tissues from individuals of different ages, sexes, and hair loss conditions using immunohistochemistry (IHC), quantitative PCR (qPCR), and reanalysis of publicly available RNA-sequencing (RNA-seq) datasets. Androgen receptor (AR) localization was assessed in multiple scalp compartments. AKR1C expression was also analyzed in immortalized human sebaceous gland cells (SEB-1) and dermal papilla cells (DPCs). In addition, the effect of sulforaphane on AKR1C expression was evaluated. Results AKR1Cs were strongly expressed in male sebaceous glands (SGs) but declined with age. AKR1C4, previously considered liver specific, was detected in SGs and hair follicles (HFs) by IHC and further confirmed by qPCR in SEB-1 cells and DPCs. AR expression was predominant in SGs, with lower levels in sweat glands, the epidermal granular layer, and the HF infundibulum, but not detected in dermal papillae and bulge regions. AR localization was cytoplasmic in the epidermis but nuclear in SGs and sweat glands, and was unaffected by age, sex, or hair loss condition. Sulforaphane treatment upregulated AKR1C expression in both SEB-1 cells and DPCs. Conclusions We identify scalp SGs as a principal site of AR expression and AKR1C-mediated androgen inactivation, including AKR1C4, and demonstrate that AKR1C expression in SGs is sex dependent and declines with age. These findings suggest that age-associated changes in SG steroid metabolism may influence local androgen metabolism within the scalp microenvironment, with implications for HF homeostasis during aging.
Fracture repair remains a significant clinical challenge in orthopedics, particularly in aging populations. Accumulating evidence indicates that cellular senescence critically modulates the fracture microenvironment via the senescence-associated secretory phenotype (SASP). The SASP constitutes a complex secretory program of senescent cells that releases pro-inflammatory cytokines, growth factors, and matrix-modifying enzymes to reshape the surrounding microenvironment. Rather than being a random collection of molecules, the SASP represents a coordinated signaling network that can either promote tissue repair or drive chronic inflammation depending on its context. In this review, we apply a systematic SASP classification to the canonical four phases of fracture healing to clarify their distinct roles across these stages. During the inflammatory phase, SASP-associated (but non-exclusive) inflammatory cytokines and chemokines potentiate innate immune cell recruitment and early host defense, thereby initiating the repair cascade; in the soft-callus phase, chemotactic and angiogenic SASP components (such as CCL2, PDGF, VEGF) position mesenchymal progenitors and support chondrogenesis and neovascularization; in the hard-callus phase, osteoinductive growth factors and matrix-acting proteases (such as TGF-β, IGFBPs, MMP-9/13) promote cartilage-to-bone conversion and early mineral deposition; and in the remodeling phase, regulated SASP-mediated matrix changes couple osteoclast resorption with osteoblast formation, while sustained pro-inflammatory or profibrotic signals may hinder the fine remodeling of the structure. This stage-resolved framework elucidates the dual nature of SASP, with transient activation facilitating repair and sustained overproduction leading to impaired remodeling. This framework provides a conceptual basis for developing stage-specific interventions to enhance bone repair. Notably, many mediators discussed here overlap with the broader injury-induced inflammatory secretome and are not senescence-exclusive; where possible, we emphasize senescent-cell-enriched contributions and regulatory circuits rather than implying unique cellular origins.
Natural killer (NK) cells are innate lymphocytes that provide rapid immune surveillance through the recognition and elimination of virally infected, malignant, and stressed cells. Beyond their established roles in host defense, accumulating evidence indicates that NK cells undergo profound age-associated remodeling affecting subset distribution, receptor balance, metabolic programming, and effector function. These changes, collectively referred to as NK immunosenescence, contribute to impaired clearance of senescent cells, dysregulated inflammation, and increased susceptibility to cancer, infection, and metabolic disease. In this review, we integrate current knowledge of NK cell aging into the emerging framework of longevity medicine. Rather than introducing NK cells as a newly identified determinant of aging, we synthesize evidence positioning them as key immune effectors whose functional state reflects and influences biological aging processes. We highlight how NK cells participate in senescence surveillance, tissue homeostasis, and immunometabolic regulation across organs, and how their dysfunction intersects with multiple hallmarks of aging. We further discuss the potential utility of NK-related phenotypic and functional metrics as complementary biomarkers of immune aging, while acknowledging current limitations in specificity and prognostic validation. Finally, we examine therapeutic strategies aimed at preserving or restoring NK competence, ranging from lifestyle and nutritional interventions to cytokine-based therapies, immune checkpoint modulation, and emerging cellular platforms. While many advanced NK-targeted approaches remain investigational—particularly outside oncology settings—we outline a translational roadmap linking NK biology to actionable interventions and measurable outcomes relevant to healthspan. By situating NK cells within a systems-level view of immune aging, this review frames them as a tractable component of precision longevity medicine rather than a singular regulator of aging.
