The suppression effect of dendritic cells maturation by adipose-derived stem cells through TGF-β1 related pathway

Advances and applications of biomimetic biomaterials for endogenous skin regeneration

Endogenous regeneration is becoming an increasingly important strategy for wound healing as it facilitates skin's own regenerative potential for self-healing, thereby avoiding the risks of immune rejection and exogenous infection. However, currently applied biomaterials for inducing endogenous skin regeneration are simplistic in their structure and function, lacking the ability to accurately mimic the intricate tissue structure and regulate the disordered microenvironment. Novel biomimetic biomaterials with precise structure, chemical composition, and biophysical properties offer a promising avenue for achieving perfect endogenous skin regeneration. Here, we outline the recent advances in biomimetic materials induced endogenous skin regeneration from the aspects of structural and functional mimicry, physiological process regulation, and biophysical property design. Furthermore, novel techniques including in situ reprograming, flexible electronic skin, artificial intelligence, single-cell sequencing, and spatial transcriptomics, which have potential to contribute to the development of biomimetic biomaterials are highlighted. Finally, the prospects and challenges of further research and application of biomimetic biomaterials are discussed. This review provides reference to address the clinical problems of rapid and high-quality skin regeneration.

Adipose-derived stem cell modulate tolerogenic dendritic cell-induced T cell regulation is correlated with activation of Notch-NFκB signaling

BACKGROUND

Adipose-derived stem cells (ASCs) are recognized for their potential immunomodulatory properties. In the immune system, tolerogenic dendritic cells (DCs), characterized by an immature phenotype, play a crucial role in inducing regulatory T cells (Tregs) and promoting immune tolerance. Notch1 signaling has been identified as a key regulator in the development and function of DCs. However, the precise involvement of Notch1 pathway in ASC-mediated modulation of tolerogenic DCs and its impact on immune modulation remain to be fully elucidated. This study aims to investigate the interplay between ASCs and DCs, focusing the role of Notch1 signaling and downstream pathways in ASC-modulated tolerogenic DCs.

METHODS

Rat bone marrow-derived myeloid DCs were directly co-cultured with ASCs to generate ASC-treated DCs (ASC-DCs). Notch signaling was inhibited using DAPT, while NFκB pathways were inhibited by NEMO binding domain peptide and si-NIK. Flow cytometry assessed DC phenotypes. Real-time quantitative PCR, Western blotting and immunofluorescence determined the expression of Notch1, Jagged1 and the p52/RelB complex in ASC- DCs.

RESULTS

Notch1 and Jagged1 were highly expressed on both DCs and ASCs. ASC-DCs displayed significantly reduced levels of CD80, CD86 and MHC II compared to mature DCs. Inhibiting the Notch pathway with DAPT reversed the dedifferentiation effects. The percentage of induced CD25+/FOXP3+/CD4+ Tregs decreased when ASC-DCs were treated with DAPT (inhibition of the Notch pathway) and si-NIK (inhibition of the non-canonical NFκB pathway).

CONCLUSIONS

ASCs induce DC tolerogenicity by inhibiting maturation and promoting downstream Treg generation, involving the Notch and NFκB pathways. ASC-induced tolerogenic DCs can be a potential immunomodulatory tool for clinical application.

Obesity and Leukemia: Biological Mechanisms, Perspectives, and Challenges

PURPOSE OF REVIEW

To examine the epidemiological data on obesity and leukemia; evaluate the effect of obesity on leukemia outcomes in childhood acute lymphoblastic leukemia (ALL) survivors; assess the potential mechanisms through which obesity may increase the risk of leukemia; and provide the effects of obesity management on leukemia. Preventive (diet, physical exercise, obesity pharmacotherapy, bariatric surgery) measures, repurposing drugs, candidate therapeutic agents targeting oncogenic pathways of obesity and insulin resistance in leukemia as well as challenges of the COVID-19 pandemic are also discussed.

RECENT FINDINGS

Obesity has been implicated in the development of 13 cancers, such as breast, endometrial, colon, renal, esophageal cancers, and multiple myeloma. Leukemia is estimated to account for approximately 2.5% and 3.1% of all new cancer incidence and mortality, respectively, while it represents the most frequent cancer in children younger than 5 years. Current evidence indicates that obesity may have an impact on the risk of leukemia. Increased birthweight may be associated with the development of childhood leukemia. Obesity is also associated with worse outcomes and increased mortality in leukemic patients. However, there are several limitations and challenges in meta-analyses and epidemiological studies. In addition, weight gain may occur in a substantial number of childhood ALL survivors while the majority of studies have documented an increased risk of relapse and mortality among patients with childhood ALL and obesity. The main pathophysiological pathways linking obesity to leukemia include bone marrow adipose tissue; hormones such as insulin and the insulin-like growth factor system as well as sex hormones; pro-inflammatory cytokines, such as IL-6 and TNF-α; adipocytokines, such as adiponectin, leptin, resistin, and visfatin; dyslipidemia and lipid signaling; chronic low-grade inflammation and oxidative stress; and other emerging mechanisms. Obesity represents a risk factor for leukemia, being among the only known risk factors that could be prevented or modified through weight loss, healthy diet, and physical exercise. Pharmacological interventions, repurposing drugs used for cardiometabolic comorbidities, and bariatric surgery may be recommended for leukemia and obesity-related cancer prevention.

Stem cell-based therapy in cardiac repair after myocardial infarction: Promise, challenges, and future directions

Stem cells represent an attractive resource for cardiac regeneration. However, the survival and function of transplanted stem cells is poor and remains a major challenge for the development of effective therapies. As two main cell types currently under investigation in heart repair, mesenchymal stromal cells (MSCs) indirectly support endogenous regenerative capacities after transplantation, while induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) functionally integrate into the damaged myocardium and directly contribute to the restoration of its pump function. These two cell types are exposed to a common microenvironment with many stressors in ischemic heart tissue. This review summarizes the research progress on the mechanisms and challenges of MSCs and iPSC-CMs in post-MI heart repair, introduces several randomized clinical trials with 3D-mapping-guided cell therapy, and outlines recent findings related to the factors that affect the survival and function of stem cells. We also discuss the future directions for optimization such as biomaterial utilization, cell combinations, and intravenous injection of engineered nucleus-free MSCs.

Adipose-derived stem cells in immune-related skin disease: a review of current research and underlying mechanisms

Adipose-derived stem cells (ASCs) are a critical adult stem cell subpopulation and are widely utilized in the fields of regenerative medicine and stem cell research due to their abundance, ease of harvest, and low immunogenicity. ASCs, which are homologous with skin by nature, can treat immune-related skin diseases by promoting skin regeneration and conferring immunosuppressive effects, with the latter being the most important therapeutic mechanism. ASCs regulate the immune response by direct cell-cell communication with immune cells, such as T cells, macrophages, and B cells. In addition to cell-cell interactions, ASCs modulate the immune response indirectly by secreting cytokines, interleukins, growth factors, and extracellular vesicles. The immunomodulatory effects of ASCs have been exploited to treat many immune-related skin diseases with good therapeutic outcomes. This article reviews the mechanisms underlying the immunomodulatory effects of ASCs, as well as progress in research on immune-related skin diseases.

Sirt3 restricts tumor initiation via promoting LONP1 deacetylation and K63 ubiquitination

BACKGROUND

Sirtuin 3 (Sirt3) is a controversial regulator of carcinogenesis. It residents in the mitochondria and gradually decays during aging. In this study, we tried to investigate the role of Sirt3 in carcinogenesis and to explore its involvement in metabolic alteration.

METHODS

We generated conditional intestinal epithelium Sirt3-knockout mice by crossing Apc^Min/+; Villin-Cre with Sirt3^fl/fl (AVS) mice. The deacetylation site of Lon protease-1 (LONP1) was identified with Mass spectrometry. The metabolic flux phenotype was determined by Seahorse bioanalyzer.

RESULTS

We found that intestinal epithelial cell-specific ablation of Sirt3 promotes primary tumor growth via stabilizing mitochondrial LONP1. Notably, we newly identified that Sirt3 deacetylates human oncogene LONP1 at N terminal residue lysine 145 (K145). The LONP1 hyperacetylation-mutant K145Q enhances oxidative phosphorylation to accelerate tumor growth, whereas the deacetylation-mutant K145R produces calorie-restriction like phenotype to restrain tumorigenesis. Sirt3 deacetylates LONP1 at K145 and subsequently facilitates the ESCRT0 complex sorting and K63-ubiquitination that resulted in the degradation of LONP1. Our results sustain the notion that Sirt3 is a tumor-suppressor to maintain the appropriate ubiquitination and degradation of oncogene LONP1.

CONCLUSION

Sirt3 represents a targetable metabolic checkpoint of oncogenesis, which produces energy restriction effects via maintaining LONP1 K145 deacetylation and subsequent K63 ubiquitination.

Sinomenine promotes differentiation of induced pluripotent stem cells into immature dendritic cells with high induction of immune tolerance

BACKGROUND

Immature dendritic cells (imDCs) play an important role in the induction of donor-specific transplant immunotolerance. However, these cells have limitations, such as rapid maturation and a short lifespan in vivo. In previous studies, induced pluripotent stem cells (iPSCs) differentiated into imDCs, and sinomenine (SN) was used to inhibit the maturation of imDCs.

AIM

To study the capacity of SN to maintain iPSC-derived imDCs (SN-iPSCs-imDCs) in an immature state and the mechanism by which SN-iPSCs-imDCs induce immunotolerance.

METHODS

In this study, mouse iPSCs were induced to differentiate into imDCs in culture medium without or with SN (iPSCs-imDCs and SN-iPSCs-imDCs). The imDC-related surface markers, endocytotic capacity of fluorescein isothiocyanate-Dextran and apoptosis were analyzed by flow cytometry. The effects of iPSCs-imDCs and SN-iPSCs-imDCs on T-cell stimulatory function, and regulatory T (Treg) cell proliferative function in vitro were analyzed by mixed lymphocyte reaction. Cytokine expression was detected by ELISA. The apoptosis-related proteins of iPSCs-DCs and SN-iPSCs-DCs were analyzed by western blotting. The induced immunotolerance of SN-iPSCs-DCs was evaluated by treating recipient Balb/c skin graft mice. Statistical evaluation of graft survival was performed using Kaplan–Meier curves.

RESULTS

Both iPSCs-imDCs and SN-iPSCs-imDCs were successfully obtained, and their biological characteristics and ability to induce immunotolerance were compared. SN-iPSCs-imDCs exhibited higher CD11c levels and lower CD80 and CD86 levels compared with iPSCs-imDCs. Reduced major histocompatibility complex II expression, worse T-cell stimulatory function, higher Treg cell proliferative function and stronger endocytotic capacity were observed with SN-iPSCs-imDCs (P < 0.05). The levels of interleukin (IL)-2, IL-12, interferon-γ in SN-iPSCs-imDCs were lower than those in iPSCs-imDCs, whereas IL-10 and transforming growth factor-β levels were higher (P < 0.05). The apoptosis rate of these cells was significantly higher (P < 0.05), and the expression levels of cleaved caspase3, Bax and cleaved poly(ADP-ribose) polymerase were higher after treatment with lipopolysaccharides, but Bcl-2 was reduced. In Balb/c mice recipients immunized with iPSCs-imDCs or SN-iPSCs-imDCs 7 d before skin grafting, the SN-iPSCs-imDCs group showed lower ability to inhibit donor-specific CD4⁺ T-cell proliferation (P < 0.05) and a higher capacity to induce CD4⁺CD25⁺FoxP3⁺ Treg cell proliferation in the spleen (P < 0.05). The survival span of C57bl/6 skin grafts was significantly prolonged in immunized Balb/c recipients with a donor-specific pattern.

CONCLUSION

This study demonstrated that SN-iPSCs-imDCs have potential applications in vitro and in vivo for induction of immunotolerance following organ transplantation.

Short-Term Autophagy Preconditioning Upregulates the Expression of COX2 and PGE2 and Alters the Immune Phenotype of Human Adipose-Derived Stem Cells In Vitro

Human adipose-derived stem cells (hASCs) are potent modulators of inflammation and promising candidates for the treatment of inflammatory and autoimmune diseases. Strategies to improve hASC survival and immunoregulation are active areas of investigation. Autophagy, a homeostatic and stress-induced degradative pathway, plays a crucial role in hASC paracrine signaling—a primary mechanism of therapeutic action. Therefore, induction of autophagy with rapamycin (Rapa), or inhibition with 3-methyladenine (3-MA), was examined as a preconditioning strategy to enhance therapeutic efficacy. Following preconditioning, both Rapa and 3-MA-treated hASCs demonstrated preservation of stemness, as well as upregulated transcription of cyclooxygenase-2 (COX2) and interleukin-6 (IL-6). Rapa-ASCs further upregulated TNFα-stimulated gene-6 (TSG-6) and interleukin-1 beta (IL-1β), indicating additional enhancement of immunomodulatory potential. Preconditioned cells were then stimulated with the inflammatory cytokine interferon-gamma (IFNγ) and assessed for immunomodulatory factor production. Rapa-pretreated cells, but not 3-MA-pretreated cells, further amplified COX2 and IL-6 transcripts following IFNγ exposure, and both groups upregulated secretion of prostaglandin-E2 (PGE2), the enzymatic product of COX2. These findings suggest that a 4-h Rapa preconditioning strategy may bestow the greatest improvement to hASC expression of cytokines known to promote tissue repair and regeneration and may hold promise for augmenting the therapeutic potential of hASCs for inflammation-driven pathological conditions.

Supercritical Carbon Dioxide Decellularized Bone Matrix Seeded with Adipose-Derived Mesenchymal Stem Cells Accelerated Bone Regeneration

Large bone fractures with segmental defects are a vital phase to accelerate bone integration. The present study examined the role of supercritical carbon dioxide (scCO2) decellularized bone matrix (scDBM) seeded with allogeneic adipose-derived mesenchymal stem cells (ADSC) as bio-scaffold for bone regeneration. Bio-scaffold produced by seeding ADSC to scDBM was evaluated by scanning electron microscopy (SEM). Rat segmental femoral defect model was used as a non-union model to investigate the callus formation in vivo. Histological analysis and osteotomy gap closure in the defect area were analyzed at 12 and 24 weeks post-surgery. Immunohistochemical expression of Ki-67, BMP-2 and osteocalcin was evaluated to assess the ability of new bone formation scDBM. ADSC was found to attach firmly to scDBM bioscaffold as evidenced from SEM images in a dose-dependent manner. Callus formation was observed using X-ray bone imaging in the group with scDBM seeded with 2 × 106 and 5 × 106 ASCs group at the same time-periods. H&E staining revealed ASCs accelerated bone formation. IHC staining depicted the expression of Ki-67, BMP-2, and osteocalcin was elevated in scDBM seeded with 5 × 106 ASCs group at 12 weeks after surgery, relative to other experimental groups. To conclude, scDBM is an excellent scaffold that enhanced the attachment and recruitment of mesenchymal stem cells. scDBM seeded with ASCs accelerated new bone formation.

Exosome: The Regulator of the Immune System in Sepsis

Sepsis is a syndrome comprised of a series of life-threatening organ dysfunctions caused by a maladjusted body response to infection with no effective treatment. There is growing evidence that the immune system plays a core role in sepsis. Pathogens cause abnormal host immune response and eventually lead to immunosuppression, which is an important cause of death in patients with sepsis. Exosomes are vesicles derived from double invagination of plasma membrane, associating with immune responses closely. The cargos delivered by exosomes into recipient cells, especially immune cells, effectively alter their response and functions in sepsis. In this review, we focus on the effects and mechanisms of exosomes on multiple immune cells, as well as the role of immune cell-derived exosomes in sepsis. This is helpful for us to have an in-depth understanding of the mechanism of immune disorders in sepsis. Exosomes is also expected to become a novel target and therapeutic approach for sepsis.

Is There A Causal Relationship between Childhood Obesity and Acute Lymphoblastic Leukemia? A Review

Childhood obesity is a growing epidemic with numerous global health implications. Over the past few years, novel insights have emerged about the contribution of adult obesity to cancer risk, but the evidence base is far more limited in children. While pediatric patients with acute lymphoblastic leukemia (ALL) are at risk of obesity, it is unclear if there are potential causal mechanisms by which obesity leads to ALL development. This review explores the endocrine, metabolic and immune dysregulation triggered by obesity and its potential role in pediatric ALL's genesis. We describe possible mechanisms, including adipose tissue attraction and protection of lymphoblasts, and their impact on ALL chemotherapies' pharmacokinetics. We also explore the potential contribution of cytokines, growth factors, natural killer cells and adipose stem cells to ALL initiation and propagation. While there are no current definite causal links between obesity and ALL, critical questions persist as to whether the adipose tissue microenvironment and endocrine actions can play a causal role in childhood ALL, and there is a need for more research to address these questions.

Targeted Migration of Human Adipose-Derived Stem Cells to Secondary Lymphoid Organs Enhances Their Immunomodulatory Effect and Prolongs the Survival of Allografted Vascularized Composites

The targeted delivery of therapeutic agents to secondary lymphoid organs (SLOs), which are the niches for immune initiation, provides an unprecedented opportunity for immune intolerance induction. The alloimmune rejection postvascularized composite allotransplantation (VCA) is mediated by T lymphocytes. Human adipose-derived stem cells (hASCs) possess the superiority of convenient availability and potent immunoregulatory property, but their therapeutic results in the VCA are unambiguous thus far. Chemokine receptor 7 (CCR7) can specifically guide immune cells migrating into SLOs. There, the genes of CCR7-GFP or GFP alone were introduced into hASCs by lentivirus. hASCs/CCR7 maintained the multidifferentiation and immunoregulatory abilities, but it gained the migration capacity elicited by secondary lymphoid organ chemokine (SCL) (CCR7 ligand) in vitro. Noteworthily, intravenously infused hASCs/CCR7 targetedly relocated in the T-cell aggression area in SLOs. In a rat VCA model, hASCs/GFP transfusion had a rare effect on the allografted vascularized composite. However, hASCs/CCR7 infusion potently prolonged the grafts' survival time. The ameliorated pathologic exhibition and the regulated inflammatory cytokines in the peripheral blood were also observed. The altered axis of Th1/Th2 and Tregs/Th17 in SLOs may underlie the downregulated rejection response. Moreover, the proteomic examination of splenic T lymphocytes also confirmed that hASCs/CCR7 decreased the proteins related to cytokinesis, lymphocyte proliferation, differentiation, and apoptotic process. In conclusion, our present study demonstrated that targeted migration of hASCs/CCR7 to SLOs highly intensifies their in vivo immunomodulatory effect in the VCA model for the first time. We believe this SLO-targeting strategy may improve the clinical therapeutic efficacy of hASC for allogeneic and autogenic immune disease. Stem Cells 2019;37:1581-1594.

Immunomodulatory effect of oleoylethanolamide in dendritic cells via TRPV1/AMPK activation

Oleoylethanolamide (OEA) is an endogenous lipid mediator involved in the control of feeding, body weight, and energy metabolism. However, whether OEA modulates maturation of dendritic cells (DCs) has never been addressed. Hence, we evaluated the effect of OEA on DCs maturation in bone marrow-derived DCs (BMDCs) in four aspects: (a) Cell surface markers were determined using flow cytometric analysis; (b) cell mobile ability was testified with the transwell assay; (c) stimulation of T cells proliferation was performed in a coculture system; and (d) cytokine production was measured using polymerase chain reaction (PCR). The result showed that, in mature BMDCs induced by lipopolysaccharides (LPS), the OEA treatment decreased expressions of cell surface markers, reduced cell migration, diminished the proliferation of cocultured T cells, and regulated cytokine production of BMDCs, indicating the modulatory effect of OEA on DCs maturation. Furthermore, to explore the underlying mechanism of the immunomodulatory effect of OEA, we used antagonists of transient receptor potential vanilloid-1 (TRPV1) and AMP-activated protein kinase (AMPK), determined the protein expressions of TRPV1/AMPK and Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) using western blot, and measured the intracellular calcium concentration using calcium imaging. The result illustrated that OEA downregulated TLR4/NF-κB, the classical pathway leading to DCs maturation induced by LPS, through the activation of TRPV1 and AMPK. Collectively, the present study suggests that OEA suppresses DCs maturation through the activation of TRPV1/AMPK. These findings increase our understanding of this endogenous lipid OEA.

Old Friends, immunoregulation, and stress resilience

There is a considerable body of evidence indicating that chronic adverse experience, especially chronic psychosocial stress/trauma, represents a major risk factor for the development of many somatic and affective disorders, including inflammatory bowel disease (IBD) and posttraumatic stress disorder (PTSD). However, the mechanisms underlying the development of chronic stress-associated disorders are still in large part unknown, and current treatment and prevention strategies lack efficacy and reliability. A greater understanding of mechanisms involved in the development and persistence of chronic stress-induced disorders may lead to novel approaches to prevention and treatment of these disorders. In this review, we provide evidence indicating that increases in immune (re-)activity and inflammation, potentially promoted by a reduced exposure to immunoregulatory microorganisms ("Old Friends") in today's modern society, may be causal factors in mediating the vulnerability to development and persistence of stress-related pathologies. Moreover, we discuss strategies to increase immunoregulatory processes and attenuate inflammation, as for instance contact with immunoregulatory Old Friends, which appears to be a promising strategy to promote stress resilience and to prevent/treat chronic stress-related disorders.