CCL5/CCR1 axis regulates multipotency of human adipose tissue derived stromal cells

Human platelet lysate-cultured adipose-derived stem cell sheets promote angiogenesis and accelerate wound healing via CCL5 modulation

BACKGROUND

A rising population faces challenges with healing-impaired cutaneous wounds, often leading to physical disabilities. Adipose-derived stem cells (ASCs), specifically in the cell sheet format, have emerged as a promising remedy for impaired wound healing. Human platelet lysate (HPL) provides an attractive alternative to fetal bovine serum (FBS) for culturing clinical-grade ASCs. However, the potential of HPL sheets in promoting wound healing has not been fully investigated. This study aimed to explore the anti-fibrotic and pro-angiogenic capabilities of HPL-cultured ASC sheets and delve into the molecular mechanism.

METHODS

A rat burn model was utilized to evaluate the efficacy of HPL-cultured ASC sheets in promoting wound healing. ASC sheets were fabricated with HPL, and those with FBS were included for comparison. Various analyses were conducted to assess the impact of HPL sheets on wound healing. Histological examination of wound tissues provided insights into aspects such as wound closure, collagen deposition, and overall tissue regeneration. Immunofluorescence was employed to assess the presence and distribution of transplanted ASCs after treatment. Further in vitro studies were conducted to decipher the specific factors in HPL sheets contributing to angiogenesis.

RESULTS

HPL-cultured ASC sheets significantly accelerated wound closure, fostering ample and organized collagen deposition in the neo-dermis. Significantly more retained ASCs were observed in wound tissues treated with HPL sheets compared to the FBS counterparts. Moreover, HPL sheets mitigated macrophage recruitment and decreased subsequent wound tissue fibrosis in vivo. Immunohistochemistry also indicated enhanced angiogenesis in the HPL sheet group. The in vitro analyses showed upregulation of C-C motif chemokine ligand 5 (CCL5) and angiogenin in HPL sheets, including both gene expression and protein secretion. Culturing endothelial cells in the conditioned media compared to media supplemented with CCL5 or angiogenin suggested a correlation between CCL5 and the pro-angiogenic effect of HPL sheets. Additionally, through neutralizing antibody experiments, we further validated the crucial role of CCL5 in HPL sheet-mediated angiogenesis in vitro.

CONCLUSIONS

The present study underscores CCL5 as an essential factor in the pro-angiogenic effect of HPL-cultured ASC sheets during the wound healing process. These findings highlight the potential of HPL-cultured ASC sheets as a promising therapeutic option for healing-impaired cutaneous wounds in clinical settings. Furthermore, the mechanism exploration yields valuable information for optimizing regenerative strategies with ASC products.

BRIEF ACKNOWLEDGMENT

This research was supported by the National Science and Technology Council, Taiwan (NSTC112-2321-B-002-018), National Taiwan University Hospital (111C-007), and E-Da Hospital-National Taiwan University Hospital Joint Research Program (111-EDN0001, 112-EDN0002).

The myokine CCL5 recruits subcutaneous preadipocytes and promotes intramuscular fat deposition in obese mice

Intramuscular fat (IMF) refers to the lipid stored in skeletal muscle tissue. The number and size of intramuscular adipocytes are the primary factors that regulate IMF content. Intramuscular adipocytes can be derived from either in situ or ectopic migration. In this study, it was discovered that the regulation of IMF levels is achieved through the chemokine (C-C motif) ligand 5 (CCL5)/chemokine (C-C motif) receptor 5 (CCR5) pathway by modulating adipocyte migration. In coculture experiments, C2C12 myotubes were more effective in promoting the migration of 3T3-L1 preadipocytes than C2C12 myoblasts, along with increasing CCL5. Correspondingly, overexpressing the CCR5, one of the receptors of CCL5, in 3T3-L1 preadipocytes facilitated their migration. Conversely, the application of the CCL5/CCR5 inhibitor, MARAVIROC (MVC), reduced this migration. In vivo, transplanted experiments of subcutaneous adipose tissue (SCAT) from transgenic mice expressing green fluorescent protein (GFP) provided evidence that injecting recombinant CCL5 (rCCL5) into skeletal muscle promotes the migration of subcutaneous adipocytes to the skeletal muscle. The level of CCL5 in skeletal muscle increased with obesity. Blocking the CCL5/CCR5 axis by MVC inhibited IMF deposition, whereas elevated skeletal muscle CCL5 promoted IMF deposition in obese mice. These results establish a link between the IMF and the CCL5/CCR5 pathway, which could have a potential application for modulating IMF through adipocyte migration.NEW & NOTEWORTHY C2C12 myotubes attract 3T3-L1 preadipocyte migration regulated by the chemokine (C-C motif) ligand 5 (CCL5)/ chemokine (C-C motif) receptor 5 (CCR5) axis. High levels of skeletal muscle-specific CCL5 promote the migration of subcutaneous adipocytes to skeletal muscle and induce the intramuscular fat (IMF) content.

Differential Gene Expression of Subcutaneous Adipose Tissue among Lean, Obese, and after RYGB (Different Timepoints): Systematic Review and Analysis

The main roles of adipose tissue include triglycerides storage and adipokine secretion, which regulate energy balance and inflammation status. In obesity, adipocyte dysfunction leads to proinflammatory cytokine production and insulin resistance. Bariatric surgery is the most effective treatment for obesity, the gold-standard technique being Roux-en-Y gastric bypass (RYGB). Since metabolic improvements after RYGB are clear, a better understanding of adipose tissue molecular modifications could be derived from this study. Thus, the aim of this systematic review was to find differentially expressed genes in subcutaneous adipose tissue of lean, obese and post-RYGB (distinct timepoints). To address this objective, publications from 2015-2022 reporting gene expression (candidate genes or transcriptomic approach) of subcutaneous adipose tissue from lean and obese individuals before and after RGYB were searched in PubMed, Elsevier, and Springer Link. Excluded publications were reviews, studies analyzing serum, other types of tissues, or bariatric procedures. A risk-of-bias summary was created for each paper using Robvis, to finally include 17 studies. Differentially expressed genes in post-RYGB vs. obese and lean vs. obese were obtained and the intersection among these groups was used for analysis and gene classification by metabolic pathway. Results showed that the lean state as well as the post-RYGB is similar in terms of increased expression of insulin-sensitizing molecules, inducing lipogenesis over lipolysis and downregulating leukocyte activation, cytokine production and other factors that promote inflammation. Thus, massive weight loss and metabolic improvements after RYGB are accompanied by gene expression modifications reverting the "adipocyte dysfunction" phenomenon observed in obesity conditions.

Resolution therapy: Harnessing efferocytic macrophages to trigger the resolution of inflammation

Several chronic inflammatory diseases are associated with non-resolving inflammation. Conventional anti-inflammatory drugs fail to completely cure these diseases. Resolution pharmacology is a new therapeutic approach based on the use of pro-resolving mediators that accelerate the resolution phase of inflammation by targeting the productive phase of inflammation. Indeed, pro-resolving mediators prevent leukocyte recruitment and induce apoptosis of accumulated leukocytes. This approach is now called resolution therapy with the introduction of complex biological drugs and cell-based therapies. The main objective of resolution therapy is to specifically reduce the duration of the resolution phase to accelerate the return to homeostasis. Under physiological conditions, macrophages play a critical role in the resolution of inflammation. Indeed, after the removal of apoptotic cells (a process called efferocytosis), macrophages display anti-inflammatory reprogramming and subsequently secrete multiple pro-resolving factors. These factors can be used as resolution therapy. Here, we review the different mechanisms leading to anti-inflammatory reprogramming of macrophages after efferocytosis and the pro-resolving factors released by these efferocytic macrophages. We classify these mechanisms in three different categories: macrophage reprogramming induced by apoptotic cell-derived factors, by molecules expressed by apoptotic cells (i.e., "eat-me" signals), and induced by the digestion of apoptotic cell-derived materials. We also evoke that macrophage reprogramming may result from cooperative mechanisms, for instance, implicating the apoptotic cell-induced microenvironment (including cellular metabolites, specific cytokines or immune cells). Then, we describe a new drug candidate belonging to this resolution therapy. This candidate, called SuperMApo, corresponds to the secretome of efferocytic macrophages. We discuss its production, the pro-resolving factors present in this drug, as well as the results obtained in experimental models of chronic (e.g., arthritis, colitis) and acute (e.g., peritonitis or xenogeneic graft-versus-host disease) inflammatory diseases.

Lifestyle and Dietary Habits Affect Plasma Levels of Specific Cytokines in Healthy Subjects

Low-grade chronic inflammation (LGCI) is a common feature of non-communicable diseases. Cytokines play a crucial role in LGCI. This study aimed to assess how LGCI risk factors [e.g., age, body mass index (BMI), smoke, physical activity, and diet] may impact on specific cytokine levels in a healthy population. In total, 150 healthy volunteers were recruited and subjected to questionnaires about the last 7-day lifestyle, including smoking habit, physical activity, and food frequency. A panel of circulating cytokines, chemokines, and growth factors was analyzed by multiplex ELISA. BMI showed the heaviest impact on the correlation between LGCI-related risk factors and cytokines and was significantly associated with CRP levels. Aging was characterized by an increase in IL-1b, eotaxin, MCP-1, and MIP-1α. Smoking was related to higher levels of IL-1b and CCL5/RANTES, while physical activity was related to MIP-1α. Within the different eating habits, CRP levels were modulated by eggs, red meat, shelled fruits, and greens consumption; however, these associations were not confirmed in a multivariate model after adjusting for BMI. Nevertheless, red meat consumption was associated with an inflammatory pattern, characterized by an increase in IL-6 and IL-8. IL-8 levels were also increased with the frequent intake of sweets, while a higher intake of shelled fruits correlated with lower levels of IL-6. Moreover, IL-6 and IL-8 formed a cluster that also included IL-1b and TNF-α. In conclusion, age, BMI, smoke, physical activity, and dietary habits are associated with specific cytokines that may represent potential markers for LGCI.

UTP Regulates the Cardioprotective Action of Transplanted Stem Cells Derived From Mouse Cardiac Adipose Tissue

Adipose tissue is a source of stem cells with a high potential of differentiation for cell-based regenerative therapies. We previously identified mouse P2Y_2, an ATP and UTP nucleotide receptor, as a regulator of adipogenic and endothelial differentiation of cardiac adipose-derived stem cells (cADSC). We investigated here the potential involvement of P2Y₂ receptor in the cardioprotective action of undifferentiated cADSC transplantation in mouse ischemic heart. Transplantation of cADSC was realized in the periphery of the infarcted zone of ischemic heart, 3 days after left anterior descending artery ligation. A strong reduction of collagen stained area was observed 14 days after cADSC injection, compared to PBS injection. Interestingly, loss of P2Y₂ expression totally inhibits the ability of transplanted cADSC to reduce cardiac fibrosis. A detailed gene ontology enrichment analysis was realized by comparing RNA-sequencing data obtained for UTP-treated wild type cASDC and UTP-treated P2Y₂-null cASDC. We identified UTP target genes linked to extracellular matrix organization such as matrix metalloproteinases and various collagen types, UTP target genes related to macrophage chemotaxis and differentiation into pro-fibrotic foam cells, and a significant number of UTP target genes linked to angiogenesis regulation. More particularly, we showed that UTP regulated the secretion of CCL5, CXCL5, and CCL12 chemokines and serum amyloid apolipoprotein 3, in the supernatants of UTP-treated cADSC. Interestingly, CCL5 is reported as a key factor in post-infarction heart failure and in the reparative and angiogenic action of transplanted ADSC on ischemic tissue. We investigated then if a UTP-pretreatment of cADSC amplifies their effect on cardiac revascularization in mouse ischemic heart. Transplantation of cADSC was able to increase peri-infarct capillary density, 14 days after their injection. This beneficial effect on cardiac revascularization was enhanced by a UTP-pretreatment of cADSC before their transplantation, and not observed using P2Y₂-null cADSC. Our data support that the efficacy of transplanted cADSC can be regulated by the release of inflammatory mediators such as extracellular nucleotides in the ischemic site. The present study highlights the P2Y₂ receptor as a regulator of cADSC cardioprotective action, and as a potential target for the therapeutic use of undifferentiated cADSC in post-ischemic cardiac ischemia.

Analysis of the Replication Mechanisms of the Human Papillomavirus Genomes

The life-cycle of human papillomaviruses (HPVs) includes three distinct phases of the viral genome replication. First, the viral genome is amplified in the infected cells, and this amplification is often accompanied by the oligomerization of the viral genomes. Second stage includes the replication of viral genomes in concert with the host cell genome. The viral genome is further amplified during the third stage of the viral-life cycle, which takes place only in the differentiated keratinocytes. We have previously shown that the HPV18 genomes utilize at least two distinct replication mechanisms during the initial amplification. One of these mechanisms is a well-described bidirectional replication via theta type of replication intermediates. The nature of another replication mechanism utilized by HPV18 involves most likely recombination-dependent replication. In this paper, we show that the usage of different replication mechanisms is a property shared also by other HPV types, namely HPV11 and HPV5. We further show that the emergence of the recombination dependent replication coincides with the oligomerization of the viral genomes and is dependent on the replicative DNA polymerases. We also show that the oligomeric genomes of HPV18 replicate almost exclusively using recombination dependent mechanism, whereas monomeric HPV31 genomes replicate bi-directionally during the maintenance phase of the viral life-cycle.

PAI-1-Dependent Inactivation of SMAD4-Modulated Junction and Adhesion Complex in Obese Endometrial Cancer

While plasminogen activator inhibitor-1 (PAI-1) is known to potentiate cellular migration via proteolytic regulation, this adipokine is implicated as an oncogenic ligand in the tumor microenvironment. To understand the underlying paracrine mechanism, here, we conduct transcriptomic analysis of 1,898 endometrial epithelial cells (EECs) exposed and unexposed to PAI-1-secreting adipose stromal cells. The PAI-1-dependent action deregulates crosstalk among tumor-promoting and tumor-repressing pathways, including transforming growth factor β (TGF-β). When PAI-1 is tethered to lipoprotein receptor-related protein 1 (LRP1), the internalized signaling causes downregulation of SMAD4 at the transcriptional and post-translational levels that attenuates TGF-β-related transcription programs. Repression of genes encoding the junction and adhesion complex preferentially occurs in SMAD4-underexpressed EECs of persons with obesity. The findings highlight a role of PAI-1 signaling that renders ineffective intercellular communication for the development of adiposity-associated endometrial cancer.

Lin et al. demonstrate that PAI-1 secreted by adipose stromal cells interacts with LRP1 to repress TGF-β/SMAD4-regulated genes linked to cellular junction and adhesion complexes. This action disrupts cell-cell communication and facilitates the development of obesity-driven endometrial cancer.

CCR1 Activation Promotes Neuroinflammation Through CCR1/TPR1/ERK1/2 Signaling Pathway After Intracerebral Hemorrhage in Mice

The activation of C-C chemokine receptor type 1 (CCR1) has been shown to be pro-inflammatory in several animal models of neurological diseases. The objective of this study was to investigate the activation of CCR1 on neuroinflammation in a mouse model of intracerebral hemorrhage (ICH) and the mechanism of CCR1/tetratricopeptide repeat 1 (TPR1)/extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway in CCR1-mediated neuroinflammation. Adult male CD1 mice (n = 210) were used in the study. The selective CCR1 antagonist Met-RANTES was administered intranasally at 1 h after autologous blood injection. To elucidate potential mechanism, a specific ERK1/2 activator (ceramide C6) was administered prior to Met-RANTES treatment; CCR1 activator (recombinant CCL5, rCCL5) and TPR1 CRISPR were administered in naïve mouse. Neurobehavioral assessments, brain water content, immunofluorescence staining, and western blot were performed. The endogenous expressions of CCR1, CCL5, TPR1, and p-ERK1/2 were increased in the brain after ICH. CCR1 were expressed on microglia, neurons, and astrocytes. The inhibition of CCR1 with Met-RANTES improved neurologic function, decreased brain edema, and suppressed microglia/macrophage activations and neutrophil infiltration after ICH. Met-RANTES treatment decreased expressions of CCR1, TPR1, p-ERK, TNF-α, and IL-1β, which was reversed by ceramide C6. The brain CCR1 activation by rCCL5 injection in naïve mouse resulted in neurological deficits and increased expressions of CCR1, TPR1, p-ERK, TNF-α, and IL-1β. These detrimental effects of rCCL5 were reversed by TPR1 knockdown using TPR1 CRISPR. Our study demonstrated that CCR1 activation promoted neuroinflammation through CCR1/TPR1/ERK1/2 signaling pathway after ICH in mice. CCR1 inhibition with Met-RANTES attenuated neuroinflammation, thereby reducing brain edema and improving neurobehavioral functions. Targeting CCR1 activation may provide a promising therapeutic approach in the management of ICH patients.

Plasticity of patient-matched normal mammary epithelial cells is dependent on autologous adipose-derived stem cells

Due to the increasing clinical application of adipose-derived stem cells (ADSC), e.g. lipotransfer for breast reconstruction, this study aimed to gain novel insights regarding ADSC influence on breast tissue remodeling and determine patient-dependent factors affecting lipotransfer as well as begin to address its oncological risks. The ADSC secretome was analyzed from five normal breast reduction patients and contained elevated levels of growth factors, cytokines and proteins mediating invasion. ADSC/ADSC secretomes were tested for their influence on the function of primary mammary epithelial cells, and tumor epithelial cells using cell culture assays. ADSC/ADSC secretomes significantly stimulated proliferation, transmigration and 3D-invasion of primary normal and tumor epithelial cells. IL-6 significantly induced an EMT and invasion. The ADSC secretome significantly upregulated normal epithelial cell gene expression including MMPs and ECM receptors. Our study supports that ADSC and its secretome promote favorable conditions for normal breast tissue remodeling by changing the microenvironment. and may also be important regarding residual breast cancer cells following surgery.

Activity of CK2α protein kinase is required for efficient replication of some HPV types

Inhibition of human papillomavirus (HPV) replication is a promising therapeutic approach for intervening with HPV-related pathologies. Primary targets for interference are two viral proteins, E1 and E2, which are required for HPV replication. Both E1 and E2 are phosphoproteins; thus, the protein kinases that phosphorylate them might represent secondary targets to achieve inhibition of HPV replication. In the present study, we show that CX4945, an ATP-competitive small molecule inhibitor of casein kinase 2 (CK2) catalytic activity, suppresses replication of different HPV types, including novel HPV5NLuc, HPV11NLuc and HPV18NLuc marker genomes, but enhances the replication of HPV16 and HPV31. We further corroborate our findings using short interfering RNA (siRNA)-mediated knockdown of CK2 α and α' subunits in U2OS and CIN612 cells; we show that while both subunits are expressed in these cell lines, CK2α is required for HPV replication, but CK2α' is not. Furthermore, we demonstrate that CK2α acts in a kinase activity-dependent manner and regulates the stability and nuclear retention of endogenous E1 proteins of HPV11 and HPV18. This unique feature of CK2α makes it an attractive target for developing antiviral agents.

Prostaglandin D2 Receptor DP1 Antibodies Predict Vaccine-induced and Spontaneous Narcolepsy Type 1: Large-scale Study of Antibody Profiling

BACKGROUND

Neuropathological findings support an autoimmune etiology as an underlying factor for loss of orexin-producing neurons in spontaneous narcolepsy type 1 (narcolepsy with cataplexy; sNT1) as well as in Pandemrix influenza vaccine-induced narcolepsy type 1 (Pdmx-NT1). The precise molecular target or antigens for the immune response have, however, remained elusive.

METHODS

Here we have performed a comprehensive antigenic repertoire analysis of sera using the next-generation phage display method - mimotope variation analysis (MVA). Samples from 64 children and adolescents were analyzed: 10 with Pdmx-NT1, 6 with sNT1, 16 Pandemrix-vaccinated, 16 H1N1 infected, and 16 unvaccinated healthy individuals. The diagnosis of NT1 was defined by the American Academy of Sleep Medicine international criteria of sleep disorders v3.

FINDINGS

Our data showed that although the immunoprofiles toward vaccination were generally similar in study groups, there were also striking differences in immunoprofiles between sNT1 and Pdmx-NT1 groups as compared with controls. Prominent immune response was observed to a peptide epitope derived from prostaglandin D2 receptor (DP1), as well as peptides homologous to B cell lymphoma 6 protein. Further validation confirmed that these can act as true antigenic targets in discriminating NT1 diseased along with a novel epitope of hemagglutinin of H1N1 to delineate exposure to H1N1.

INTERPRETATION

We propose that DP1 is a novel molecular target of autoimmune response and presents a potential diagnostic biomarker for NT1. DP1 is involved in the regulation of non-rapid eye movement (NREM) sleep and thus alterations in its functions could contribute to the disturbed sleep regulation in NT1 that warrants further studies. Together our results also show that MVA is a helpful method for finding novel peptide antigens to classify human autoimmune diseases, possibly facilitating the design of better therapies.

CCL5 deficiency rescues pulmonary vascular dysfunction, and reverses pulmonary hypertension via caveolin-1-dependent BMPR2 activation

Pulmonary arterial hypertension (PAH) is a devastating cardiopulmonary disorder characterized by pulmonary arterial remodeling mainly due to excess cellular proliferation and apoptosis resistance of pulmonary arterial smooth muscle cells (PASMCs). Reduced bone morphogenetic protein receptor 2 (BMPR2) expression in patients with PAH impairs pulmonary arterial endothelial cells (PAECs) function. This can adversely affect PAEC survival and promote PASMCs proliferation. We hypothesized that interventions to normalize the expression of genes that are targets of the BMPR2 signaling could restore PAECs function and prevent or reverse PAH. Here we characterized for the first time, in human PAECs, chemokine (C-C motif) ligand 5 (CCL5/RANTES) deficiency restore BMP-mediated PAECs function. In the cell culture experiments, we found that CCL5 deficiency increased apoptosis and tube formation of PAECs, but suppressed proliferation and migration of PASMCs. Silencing CCL5 expression in PAH PAECs restored bone morphogenetic protein (BMP) signaling responses and promoted phosphorylation of SMADs and transcription of ID genes. Moreover, CCL5 deficiency inhibited angiogenesis by increasing pSMAD-dependent and-independent BMPR2 signaling. This was linked mechanistically to enhanced interaction of BMPR2 with caveolin-1 via CCL5 deficiency-mediated stabilization of endothelial surface caveolin-1. Consistent with these functions, deletion of CCL5 significantly attenuated development of Sugen5416/hypoxia-induced PAH by restoring BMPR2 signaling in mice. Taken together, our findings suggest that CCL5 deficiency could reverse obliterative changes in pulmonary arteries via caveolin-1-dependent amplification of BMPR2 signaling. Our results shed light on better understanding of the disease pathobiology and provide a possible novel target for the treatment of PAH.

Human MSCs promotes colorectal cancer epithelial-mesenchymal transition and progression via CCL5/β-catenin/Slug pathway

Mesenchymal stem cells (MSCs) extensively interact with cancer cells and other stroma cells in the tumor microenvironment. However, the role of MSCs in colorectal cancer (CRC) progression and metastasis is controversial. This study was designed to identify the role of inflammation-activated-MSCs in CRC development. Our results show that tumor necrosis factor (TNF)-α-preactivated-hMSCs significantly promote the progression of colon cancer cells by enhancing cell proliferation, epithelial–mesenchymal transition, migration, and invasion. TNF-α-primed-hMSCs secrete high level of CCL5, which interacts with its receptor CCR1 expressed in colon cancer cells. Interestingly, the stimulation of colon cancer cell progression by TNF-α-primed hMSCs is associated with the upregulation ofβ-catenin signaling pathway. Blockingβ-catenin pathway significantly decreases the TNF-α-primed-conditioned medium or CCL5-mediated cancer cell progression by decreasing the enhancement of Slug, suggesting that the CCL5/β-catenin/Slug pathway plays a critical role in hMSC-mediated cancer progression. Furthermore,in vivomodel in nude mice confirms the ability of hMSCs to promote the proliferation and progression of colon cancer cells, and the upregulation of CCl5/β-catenin/Slug pathway. Taken together, the present study has demonstrated a novel pathway involving CCl5/CCR1/β-catenin/Slug, via which hMSCs promotes CRC development.

Epigenetic Modification of the CCL5/CCR1/ERK Axis Enhances Glioma Targeting in Dedifferentiation-Reprogrammed BMSCs

The success of stem cell-mediated gene therapy in cancer treatment largely depends on the specific homing ability of stem cells. We have previously demonstrated that after in vitro induction of neuronal differentiation and dedifferentiation, bone marrow stromal cells (BMSCs) revert to a primitive stem cell population (De-neu-BMSCs) distinct from naive BMSCs. We report here that De-neu-BMSCs express significantly higher levels of chemokines, and display enhanced homing abilities to glioma, the effect of which is mediated by the activated CCL5/CCR1/ERK axis. Intriguingly, we find that the activated chemokine axis in De-neu-BMSCs is epigenetically regulated by histone modifications. On the therapeutic front, we show that De-neu-BMSCs elicit stronger homing and glioma-killing effects together with cytosine deaminase/5-fluorocytosine compared with unmanipulated BMSCs in vivo. Altogether, the current study provides an insight into chemokine regulation in BMSCs, which may have more profound effects on BMSC function and their application in regenerative medicine and cancer targeting.

High glucose-induced reactive oxygen species generation promotes stemness in human adipose-derived stem cells

BACKGROUND AIMS

Adipose-derived stem cells (ASCs) represent an important source of cell therapy to treat diabetic complications. However, hyperglycemia may alter several cellular functions, so the present study aimed to investigate the influence of a diabetic environment on the stemness and differentiation capabilities of ASCs.

METHODS

Human ASCs were obtained from subcutaneous adipose tissues of diabetic (dASCs) and nondiabetic donors (nASCs) and characterized. To reproduce an in vitro hyperglycemia environment, the nASCs were also cultured under prolonged high-glucose (HG; 4.5 g/L) or low-glucose (LG; 1.0 g/L) conditions.

RESULTS

The expression of cell surface markers in dASCs and nASC was similar and characteristic of mesenchymal stem cells. Although dASCs or HG-treated nASCs exhibited decreased proliferation, enhanced expression of the pluripotent markers Sox-2, Oct-4, and Nanog was observed. Moreover, HG-treated nASCs exhibited decreased cell migration, enhanced senescence, and significantly higher intracellular reactive oxygen species (ROS), whereas their adipogenic and osteogenic differentiation capacities remained comparable to LG-treated cells. With antioxidant treatment, HG-treated nASCs showed improved cell proliferative activity without stemness enhancement. This HG-induced biological response was associated with ROS-mediated AKT attenuation. When cultured in an appropriate induction medium, the HG-treated nASCs and dASCs exhibited enhanced potential of transdifferentiation into neuron-like cells.

DISCUSSION

Despite lower proliferative activity and higher senescence in a diabetic environment, ASCs also exhibit enhanced stemness and neurogenic transdifferentiation potential via a ROS-mediated mechanism. The information is important for future application of autologous ASCs in diabetic patients.

Grafting and early expression of growth factors from adipose-derived stem cells transplanted into the cochlea, in a Guinea pig model of acoustic trauma

Noise exposure causes damage of multiple cochlear cell types producing permanent hearing loss with important social consequences. In mammals, no regeneration of either damaged hair cells or auditory neurons has been observed and no successful treatment is available to achieve a functional recovery. Loads of evidence indicate adipose-derived stem cells (ASCs) as promising tools in diversified regenerative medicine applications, due to the high degree of plasticity and trophic features. This study was aimed at identifying the path of in vivo cell migration and expression of trophic growth factors, upon ASCs transplantation into the cochlea, following noise-induced injury. ASCs were isolated in primary culture from the adipose tissue of a guinea pig, transduced using a viral vector to express the green fluorescent protein, and implanted into the scala tympani of deafened animals. Auditory function was assessed 3 and 7 days after surgery. The expression of trophic growth factors was comparatively analyzed using real-time PCR in control and noise-injured cochlear tissues. Immunofluorescence was used to assess the in vivo localization and expression of trophic growth factors in ASCs and cochleae, 3 and 7 days following homologous implantation. ASC implantation did not modify auditory function. ASCs migrated from the perilymphatic to the endolymphatic compartment, during the analyzed time course. Upon noise exposure, the expression of chemokine ligands and receptors related to the PDGF, VEGF, and TGFbeta pathways, increased in the cochlear tissues, possibly guiding in vivo cell migration. Immunofluorescence confirmed the increased expression, which appeared to be further strengthened by ASCs’ implantation. These results indicated that ASCs are able to migrate at the site of tissue damage and express trophic factors, upon intracochlear implantation, providing an original proof of principle, which could pave the way for further developments of ASC-based treatments of deafness.

Identification of co-expression gene networks, regulatory genes and pathways for obesity based on adipose tissue RNA Sequencing in a porcine model

BACKGROUND

Obesity is a complex metabolic condition in strong association with various diseases, like type 2 diabetes, resulting in major public health and economic implications. Obesity is the result of environmental and genetic factors and their interactions, including genome-wide genetic interactions. Identification of co-expressed and regulatory genes in RNA extracted from relevant tissues representing lean and obese individuals provides an entry point for the identification of genes and pathways of importance to the development of obesity. The pig, an omnivorous animal, is an excellent model for human obesity, offering the possibility to study in-depth organ-level transcriptomic regulations of obesity, unfeasible in humans. Our aim was to reveal adipose tissue co-expression networks, pathways and transcriptional regulations of obesity using RNA Sequencing based systems biology approaches in a porcine model.

METHODS

We selected 36 animals for RNA Sequencing from a previously created F2 pig population representing three extreme groups based on their predicted genetic risks for obesity. We applied Weighted Gene Co-expression Network Analysis (WGCNA) to detect clusters of highly co-expressed genes (modules). Additionally, regulator genes were detected using Lemon-Tree algorithms.

RESULTS

WGCNA revealed five modules which were strongly correlated with at least one obesity-related phenotype (correlations ranging from -0.54 to 0.72, P < 0.001). Functional annotation identified pathways enlightening the association between obesity and other diseases, like osteoporosis (osteoclast differentiation, P = 1.4E-7), and immune-related complications (e.g. Natural killer cell mediated cytotoxity, P = 3.8E-5; B cell receptor signaling pathway, P = 7.2E-5). Lemon-Tree identified three potential regulator genes, using confident scores, for the WGCNA module which was associated with osteoclast differentiation: CCR1, MSR1 and SI1 (probability scores respectively 95.30, 62.28, and 34.58). Moreover, detection of differentially connected genes identified various genes previously identified to be associated with obesity in humans and rodents, e.g. CSF1R and MARC2.

CONCLUSIONS

To our knowledge, this is the first study to apply systems biology approaches using porcine adipose tissue RNA-Sequencing data in a genetically characterized porcine model for obesity. We revealed complex networks, pathways, candidate and regulatory genes related to obesity, confirming the complexity of obesity and its association with immune-related disorders and osteoporosis.

Effect of photoperiod on the feline adipose transcriptome as assessed by RNA sequencing

Background

Photoperiod is known to cause physiological changes in seasonal mammals, including changes in body weight, physical activity, reproductive status, and adipose tissue gene expression in several species. The objective of this study was to determine the effects of day length on the adipose transcriptome of cats as assessed by RNA sequencing. Ten healthy adult neutered male domestic shorthair cats were used in a randomized crossover design study. During two 12-wk periods, cats were exposed to either short days (8 hr light:16 hr dark) or long days (16 hr light:8 hr dark). Cats were fed a commercial diet to maintain baseline body weight to avoid weight-related bias. Subcutaneous adipose biopsies were collected at wk 12 of each period for RNA isolation and sequencing.

Results

A total of 578 million sequences (28.9 million/sample) were generated by Illumina sequencing. A total of 170 mRNA transcripts were differentially expressed between short day- and long day-housed cats. 89 annotated transcripts were up-regulated by short days, while 24 annotated transcripts were down-regulated by short days. Another 57 un-annotated transcripts were also different between groups. Adipose tissue of short day-housed cats had greater expression of genes involved with cell growth and differentiation (e.g., myostatin; frizzled-related protein), cell development and structure (e.g., cytokeratins), and protein processing and ubiquitination (e.g., kelch-like proteins). In contrast, short day-housed cats had decreased expression of genes involved with immune function (e.g., plasminogen activator inhibitor 1; chemokine (C-C motif) ligand 2; C-C motif chemokine 5; T-cell activators), and altered expression of genes associated with carbohydrate and lipid metabolism.

Conclusions

Collectively, these gene expression changes suggest that short day housing may promote adipogenesis, minimize inflammation and oxidative stress, and alter nutrient metabolism in feline adipose tissue, even when fed to maintain body weight. Although this study has highlighted molecular mechanisms contributing to the seasonal metabolic changes observed in cats, future research that specifically targets and studies these biological pathways, and the physiological outcomes that are affected by them, is justified.

Protein kinase inhibitor SU6668 attenuates positive regulation of Gli proteins in cancer and multipotent progenitor cells

Observations that Glioma-associated transcription factors Gli1 and Gli2 (Gli1/2), executers of the Sonic Hedgehog (Shh) signaling pathway and targets of the Transforming Growth Factor β (TGF-β) signaling axis, are involved in numerous developmental and pathological processes unveil them as attractive pharmaceutical targets. Unc-51-like serine/threonine kinase Ulk3 has been suggested to play kinase activity dependent and independent roles in the control of Gli proteins in the context of the Shh signaling pathway. This study aimed at investigating whether the mechanism of generation of Gli1/2 transcriptional activators has similarities regardless of the signaling cascade evoking their activation. We also elucidate further the role of Ulk3 kinase in regulation of Gli1/2 proteins and examine SU6668 as an inhibitor of Ulk3 catalytic activity and a compound targeting Gli1/2 proteins in different cell-based experimental models. Here we demonstrate that Ulk3 is required not only for maintenance of basal levels of Gli1/2 proteins but also for TGF-β or Shh dependent activation of endogenous Gli1/2 proteins in human adipose tissue derived multipotent stromal cells (ASCs) and mouse immortalized progenitor cells, respectively. We show that cultured ASCs possess the functional Shh signaling axis and differentiate towards osteoblasts in response to Shh. Also, we demonstrate that similarly to Ulk3 RNAi, SU6668 prevents de novo expression of Gli1/2 proteins and antagonizes the Gli-dependent activation of the gene expression programs induced by either Shh or TGF-β. Our data suggest SU6668 as an efficient inhibitor of Ulk3 kinase allowing manipulation of the Gli-dependent transcriptional outcome.

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Ulk3 is involved in the maintenance of Gli1/2 expression.

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SU6668 prevents de novo expression of Gli1/2 proteins induced by Shh or TGF-β.

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SU6668 inhibits up-regulation of Gli1/2 proteins via Ulk3.

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Human ASCs differentiate towards osteoblasts in response to Shh.

Alternative splicing targeting the hTAF4-TAFH domain of TAF4 represses proliferation and accelerates chondrogenic differentiation of human mesenchymal stem cells

Transcription factor IID (TFIID) activity can be regulated by cellular signals to specifically alter transcription of particular subsets of genes. Alternative splicing of TFIID subunits is often the result of external stimulation of upstream signaling pathways. We studied tissue distribution and cellular expression of different splice variants of TFIID subunit TAF4 mRNA and biochemical properties of its isoforms in human mesenchymal stem cells (hMSCs) to reveal the role of different isoforms of TAF4 in the regulation of proliferation and differentiation. Expression of TAF4 transcripts with exons VI or VII deleted, which results in a structurally modified hTAF4-TAFH domain, increases during early differentiation of hMSCs into osteoblasts, adipocytes and chondrocytes. Functional analysis data reveals that TAF4 isoforms with the deleted hTAF4-TAFH domain repress proliferation of hMSCs and preferentially promote chondrogenic differentiation at the expense of other developmental pathways. This study also provides initial data showing possible cross-talks between TAF4 and TP53 activity and switching between canonical and non-canonical WNT signaling in the processes of proliferation and differentiation of hMSCs. We propose that TAF4 isoforms generated by the alternative splicing participate in the conversion of the cellular transcriptional programs from the maintenance of stem cell state to differentiation, particularly differentiation along the chondrogenic pathway.