Licensing effects of inflammatory factors and TLR ligands on the regenerative capacity of adipose-derived mesenchymal stem cells

Introduction: Adipose tissue-derived mesenchymal stem cells are promising contributors to regenerative medicine, exhibiting the ability to regenerate tissues and modulate the immune system, which is particularly beneficial for addressing chronic inflammatory ulcers and wounds. Despite their inherent capabilities, research suggests that pretreatment amplifies therapeutic effectiveness. Methods: Our experimental design exposed adipose-derived mesenchymal stem cells to six inflammatory factors for 24 h. We subsequently evaluated gene expression and proteome profile alterations and observed the wound closure rate post-treatment. Results: Specific pretreatments, such as IL-1β, notably demonstrated an accelerated wound-healing process. Analysis of gene and protein expression profiles revealed alterations in pathways associated with tissue regeneration. Discussion: This suggests that licensed cells exhibit potentially higher therapeutic efficiency than untreated cells, shedding light on optimizing regenerative strategies using adipose tissue-derived stem cells.

Foams Set a New Pace for the Release of Diclofenac Sodium

Medicated foams have emerged as promising alternatives to traditional carrier systems in pharmaceutical research. Their rapid and convenient application allows for effective treatment of extensive or hirsute areas, as well as sensitive or inflamed skin surfaces. Foams possess excellent spreading capabilities on the skin, ensuring immediate drug absorption without the need for intense rubbing. Our research focuses on the comparison of physicochemical and biopharmaceutical properties of three drug delivery systems: foam, the foam bulk liquid, and a conventional hydrogel. During the development of the composition, widely used diclofenac sodium was employed. The safety of the formulae was confirmed through an in vitro cytotoxicity assay. Subsequently, the closed Franz diffusion cell was used to determine drug release and permeation in vitro. Ex vivo Raman spectroscopy was employed to investigate the presence of diclofenac sodium in various skin layers. The obtained results of the foam were compared to the bulk liquid and to a conventional hydrogel. In terms of drug release, the foam showed a rapid release, with 80% of diclofenac released within 30 min. In summary, the investigated foam holds promising potential as an alternative to traditional dermal carrier systems, offering faster drug release and permeation.

Formulation and investigation of hydrogels containing an increased level of diclofenac sodium using risk assessment tools

Transdermal delivery of active ingredients is a challenge for pharmaceutical technology due to their inadequate penetration properties and the barrier function of the skin. The necessity of painless, effective, topical therapy for the aging population is growing, and a variety of diclofenac sodium-containing semi-solid preparations are available to alleviate the symptoms of these ailments. Our purpose was to formulate a novel composition with higher drug content to enhance drug release and permeation, thereby providing more effective therapy. Another goal was to maintain the concentration of the organic solvent mixture below 30%, to protect the skin barrier. Firstly, literature and market research were conducted, based on which the appropriate excipients for the target formulation were selected. Solubility tests were conducted with binary and ternary mixtures. As a result, the optimal ternary mixture was chosen. Hydrogels containing 1, 5, and 7% of diclofenac sodium were prepared and the stability of the formulations were studied by microscopic measurements and cytotoxicity test were carried out of the components also. The release and permeation of diclofenac sodium were investigated in different concentrations. It can be concluded that we have succeeded in preparing a topically applicable stable diclofenac sodium hydrogel with higher concentration, drug release, and improved skin permeation than the formulations available on the market.

Unraveling Transcriptome Profile, Epigenetic Dynamics, and Morphological Changes in Psoriasis-like Keratinocytes: "Insights into Similarity with Psoriatic Lesional Epidermis"

Keratinocytes are one of the primary cells affected by psoriasis inflammation. Our study aimed to delve deeper into their morphology, transcriptome, and epigenome changes in response to psoriasis-like inflammation. We created a novel cytokine mixture to mimic mild and severe psoriasis-like inflammatory conditions in cultured keratinocytes. Upon induction of inflammation, we observed that the keratinocytes exhibited a mesenchymal-like phenotype, further confirmed by increased VIM mRNA expression and results obtained from confocal microscopy. We performed RNA sequencing to achieve a more global view, revealing 858 and 6987 DEGs in mildly and severely inflamed keratinocytes, respectively. Surprisingly, we found that the transcriptome of mildly inflamed keratinocytes more closely mimicked that of the psoriatic epidermis transcriptome than the severely inflamed keratinocytes. Genes involved in the IL-17 pathway were a major contributor to the similarities of the transcriptomes between mildly inflamed KCs and psoriatic epidermis. Mild and severe inflammation led to the gene regulation of epigenetic modifiers such as HATs, HDACs, DNMTs, and TETs. Immunofluorescence staining revealed distinct 5-hmC patterns in inflamed versus control keratinocytes, and consistently low 5-mC intensity in both groups. However, the global DNA methylation assay detected a tendency of decreased 5-mC levels in inflamed keratinocytes versus controls. This study emphasizes how inflammation severity affects the transcriptomic similarity of keratinocytes to psoriatic epidermis and proves dynamic epigenetic regulation and adaptive morphological changes in inflamed keratinocytes.

Phenol-Soluble Modulin α3 Stimulates Autophagy in HaCaT Keratinocytes

BACKGROUND

Phenol-soluble modulins (PSMs) are pore-forming toxins (PFTs) produced by staphylococci. PSMs exert diverse cellular effects, including lytic, pro-apoptotic, pro-inflammatory and antimicrobial actions. Since the effects of PSMs on autophagy have not yet been reported, we evaluated the autophagic activity in HaCaT keratinocytes treated with recombinant PSMα3.

METHODS

The autophagic flux and levels of autophagic marker proteins were determined using Western blot analysis. Subcellular localization of LC3B and Beclin-1 was investigated using an indirect immunofluorescence assay. The ultrastructural features of control and PSMα3-treated cells were evaluated via transmission electron microscopy. Cytoplasmic acidification was measured via acridine orange staining. Phosphorylation levels of protein kinases, implicated in autophagy regulation, were studied using a phospho-kinase array and Western blot analysis.

RESULTS

PSMα3 facilitated the intracellular redistribution of LC3B, increased the average number of autophagosomes per cell, promoted the development of acidic vesicular organelles, elevated the levels of LC3B-II, stimulated autophagic flux and triggered a significant decrease in the net autophagic turnover rate. PSMα3 induced the accumulation of autophagosomes/autolysosomes, amphisomes and multilamellar bodies at the 0.5, 6 and 24 h time points, respectively. The phospho-Akt1/2/3 (T308 and S473), and phospho-mTOR (S2448) levels were decreased, whereas the phospho-Erk1/2 (T202/Y204 and T185/Y187) level was increased in PSMα3-treated cells.

CONCLUSIONS

In HaCaT keratinocytes, PSMα3 stimulates autophagy. The increased autophagic activity elicited by sub-lytic PSM concentrations might be an integral part of the cellular defense mechanisms protecting skin homeostasis.

Effect of Inflammatory Microenvironment on the Regenerative Capacity of Adipose-Derived Mesenchymal Stem Cells

Adipose-derived mesenchymal stem cells are increasingly being used in regenerative medicine as cell therapy targets, including in the treatment of burns and ulcers. The regenerative potential of AD-MSCs and some of their immunological properties are known from in vitro studies; however, in clinical applications, cells are used in non-ideal conditions and can behave differently in inflammatory environments, affecting the efficacy and outcome of therapy. Our aim was to investigate and map the pathways that the inflammatory microenvironment can induce in these cells. High-throughput gene expression assays were performed on AD-MSCs activated with LPS and TNFα. Analysis of RNA-Seq data showed that control, LPS-treated and TNFα-treated samples exhibited distinct gene expression patterns. LPS treatment increased the expression of 926 genes and decreased the expression of 770 genes involved in cell division, DNA repair, the cell cycle, and several metabolic processes. TNFα treatment increased the expression of 174 genes and decreased the expression of 383 genes, which are related to cell division, the immune response, cell proliferation, and differentiation. We also map the biological pathways by further investigating the most altered genes using the Gene Ontology and KEGG databases. Secreted cytokines, which are important in the immunological response, were also examined at the protein level, and a functional assay was performed to assess wound healing. Activated AD-MSC increased the secretion of IL-6, IL-8 and CXCL-10, and also the closure of wounds. AD-MSCs presented accelerated wound healing under inflammation conditions, suggesting that we could use this cell in clinical application.

Herpes Simplex Virus Infection Alters the Immunological Properties of Adipose-Tissue-Derived Mesenchymal-Stem Cells

The proper functioning of mesenchymal stem cells (MSCs) is of paramount importance for the homeostasis of the body. Inflammation and infection can alter the function of MSCs, which can also affect the regenerative potential and immunological status of tissues. It is not known whether human herpes simplex viruses 1 and 2 (HSV1 and HSV2), well-known human pathogens that can cause lifelong infections, can induce changes in MSCs. In non-healing ulcers, HSV infection is known to affect deeper tissue layers. In addition, HSV infection can recur after initially successful cell therapies. Our aim was to study the response of adipose-derived MSCs (ADMSCs) to HSV infection in vitro. After confirming the phenotype and differentiation capacity of the isolated cells, we infected the cells in vitro with HSV1-KOS, HSV1-532 and HSV2 virus strains. Twenty-four hours after infection, we examined the gene expression of the cells via RNA-seq and RT-PCR; detected secreted cytokines via protein array; and determined autophagy via Western blot, transmission electron microscopy (TEM) and fluorescence microscopy. Infection with different HSV strains resulted in different gene-expression patterns. In addition to the activation of pathways characteristic of viral infections, distinct non-immunological pathways (autophagy, tissue regeneration and differentiation) were also activated according to analyses with QIAGEN Ingenuity Pathway Analysis, Kyoto Encyclopedia of Genes and Genome and Genome Ontology Enrichment. Viral infections increased autophagy, as confirmed via TEM image analysis, and also increased levels of the microtubule-associated protein light chain 3 (LC3B) II protein. We identified significantly altered accumulation for 16 cytokines involved in tissue regeneration and inflammation. Our studies demonstrated that HSV infection can alter the viability and immunological status of ADMSCs, which may have implications for ADMSC-based cell therapies. Alterations in autophagy can affect numerous processes in MSCs, including the inhibition of tissue regeneration as well as pathological differentiation.

Does Diffusely Infiltrating Lobular Carcinoma of the Breast Arise from Epithelial-Mesenchymal Hybrid Cells?

Classic diffusely infiltrating lobular carcinoma has imaging features divergent from the breast cancers originating from the terminal ductal lobular units and from the major lactiferous ducts. Although the term "invasive lobular carcinoma" implies a site of origin within the breast lobular epithelium, we were unable to find evidence supporting this assumption. Exceptional excess of fibrous connective tissue and the unique cell architecture combined with the aberrant features at breast imaging suggest that this breast malignancy has not originated from cells lining the breast ducts and lobules. The only remaining relevant component of the fibroglandular tissue is the mesenchyme. The cells freshly isolated and cultured from diffusely infiltrating lobular carcinoma cases contained epithelial-mesenchymal hybrid cells with both epithelial and mesenchymal properties. The radiologic and histopathologic features of the tumours and expression of the mesenchymal stem cell positive markers CD73, CD90, and CD105 all suggest development in the direction of mesenchymal transition. These hybrid cells have tumour-initiating potential and have been shown to have poor prognosis and resistance to therapy targeted for malignancies of breast epithelial origin. Our work emphasizes the need for new approaches to the diagnosis and therapy of this highly fatal breast cancer subtype.

Psoriatic Resolved Skin Epidermal Keratinocytes Retain Disease-Residual Transcriptomic and Epigenomic Profiles

The disease-residual transcriptomic profile (DRTP) within psoriatic healed/resolved skin and epidermal tissue-resident memory T (TRM) cells have been proposed to be crucial for the recurrence of old lesions. However, it is unclear whether epidermal keratinocytes are involved in disease recurrence. There is increasing evidence regarding the importance of epigenetic mechanisms in the pathogenesis of psoriasis. Nonetheless, the epigenetic changes that contribute to the recurrence of psoriasis remain unknown. The aim of this study was to elucidate the role of keratinocytes in psoriasis relapse. The epigenetic marks 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) were visualized using immunofluorescence staining, and RNA sequencing was performed on paired never-lesional and resolved epidermal and dermal compartments of skin from psoriasis patients. We observed diminished 5-mC and 5-hmC amounts and decreased mRNA expression of the ten-eleven translocation (TET) 3 enzyme in the resolved epidermis. SAMHD1, C10orf99, and AKR1B10: the highly dysregulated genes in resolved epidermis are known to be associated with pathogenesis of psoriasis, and the DRTP was enriched in WNT, TNF, and mTOR signaling pathways. Our results suggest that epigenetic changes detected in epidermal keratinocytes of resolved skin may be responsible for the DRTP in the same regions. Thus, the DRTP of keratinocytes may contribute to site-specific local relapse.

Three-dimensional bioprinting of functional β-islet-like constructs

Diabetes is an autoimmune disease that ensues when the pancreas does not deliver adequate insulin or when the body cannot react to the existing insulin. Type 1 diabetes is an autoimmune disease defined by continuous high blood sugar levels and insulin deficiency due to β-cell destruction in the islets of Langerhans (pancreatic islets). Long-term complications, such as vascular degeneration, blindness, and renal failure, result from periodic glucose-level fluctuations following exogenous insulin therapy. Nevertheless, the shortage of organ donors and the lifelong dependency on immunosuppressive drugs limit the transplantation of the entire pancreas or pancreas islet, which is the therapy for this disease. Although encapsulating pancreatic islets using multiple hydrogels creates a semi-privileged environment to prevent immune rejection, hypoxia that occurs in the core of the capsules is the main hindrance that should be solved. Bioprinting technology is an innovative process in advanced tissue engineering that allows the arranging of a wide array of cell types, biomaterials, and bioactive factors as a bioink to simulate the native tissue environment for fabricating clinically applicable bioartificial pancreatic islet tissue. Multipotent stem cells have the potential to be a possible solution for donor scarcity and can be a reliable source for generating autograft and allograft functional β-cells or even pancreatic islet-like tissue. The use of supporting cells, such as endothelial cells, regulatory T cells, and mesenchymal stem cells, in the bioprinting of pancreatic islet-like construct could enhance vasculogenesis and regulate immune activity. Moreover, scaffolds bioprinted using biomaterials that can release oxygen postprinting or enhance angiogenesis could increase the function of β-cells and the survival of pancreatic islets, which could represent a promising avenue.

Toward better drug development: Three-dimensional bioprinting in toxicological research

The importance of three-dimensional (3D) models in pharmacological tests and personalized therapies is significant. These models allow us to gain insight into the cell response during drug absorption, distribution, metabolism, and elimination in an organ-like system and are suitable for toxicological testing. In personalized and regenerative medicine, the precise characterization of artificial tissues or drug metabolism processes is more than crucial to gain the safest and the most effective treatment for the patients. Using these 3D cell cultures derived directly from patient, such as spheroids, organoids, and bioprinted structures, allows for testing drugs before administration to the patient. These methods allow us to select the most appropriate drug for the patient. Moreover, they provide chance for better recovery of patients, since time is not wasted during therapy switching. These models could be used in applied and basic research as well, because their response to treatments is quite similar to that of the native tissue. Furthermore, they may replace animal models in the future because these methods are cheaper and can avoid interspecies differences. This review puts a spotlight on this dynamically evolving area and its application in toxicological testing.

Interactions between the NLRP3-Dependent IL-1β and the Type I Interferon Pathways in Human Plasmacytoid Dendritic Cells

Generally, a reciprocal antagonistic interaction exists between the antiviral type I interferon (IFN) and the antibacterial nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain containing 3 (NLRP3)-dependent IL-1β pathways that can significantly shape immune responses. Plasmacytoid dendritic cells (pDCs), as professional type I IFN-producing cells, are the major coordinators of antiviral immunity; however, their NLRP3-dependent IL-1β secretory pathway is poorly studied. Our aim was to determine the functional activity of the IL-1β pathway and its possible interaction with the type I IFN pathway in pDCs. We found that potent nuclear factor-kappa B (NF-κB) inducers promote higher levels of pro-IL-1β during priming compared to those activation signals, which mainly trigger interferon regulatory factor (IRF)-mediated type I IFN production. The generation of cleaved IL-1β requires certain secondary signals in pDCs and IFN-α or type I IFN-inducing viruses inhibit IL-1β production of pDCs, presumably by promoting the expression of various NLRP3 pathway inhibitors. In line with that, we detected significantly lower IL-1β production in pDCs of psoriasis patients with elevated IFN-α levels. Collectively, our results show that the NLRP3-dependent IL-1β secretory pathway is inducible in pDCs; however, it may only prevail under inflammatory conditions, in which the type I IFN pathway is not dominant.

Mesterséges bőrszövetek a kutatásban és a gyógyításban

Összefoglaló. A bőrpótlóknak mind a klinikumban, mind a gyógyszerkutatásokban kiemelt szerepük van. Ezek a kezdetleges mesterséges bőrszövetek segíthetik a bőr regenerálódását, modellezhetik a főbb funkciókat, de megvannak a korlátaik is, mechanikailag sérülékenyek, és nem tartósak. A legtöbb bőrpótló vagy acelluláris, vagy csak egy-két sejttípust tartalmaz. Az eredeti bőrrel megegyező szerkezetű, teljesen funkcionális mesterséges bőrszövet a mai napig nem létezik. A háromdimenziós szövetnyomtatás megoldást kínálhat erre a problémára is, hiszen a bőrszövet minden sejtes eleme felhasználható, megfelelő hidrogélek és biotinták segítségével pedig olyan komplex struktúrák hozhatók létre, amelyek képesek a bőr teljes funkcionális repertoárját biztosítani. Ez nemcsak klinikai szempontból kiemelt jelentőségű, hanem a preklinikai kísérletek esetében kiválthatja az állatmodelleket és számos toxikológiai vizsgálatot is. Orv Hetil. 2022; 163(10): 375–385.

Summary. Skin substitutes have a prominent role in therapeutic applications and drug research. These simple artificial skin tissues can support skin regeneration, in vitro they can model the main functions of the skin but they also have limitations such as being mechanically vulnerable and not durable enough. Most skin substitutes are either acellular or contain only one or two cell types. Fully functional artificial skin substitute with the same structure as the original skin has not been produced to this day. Three-dimensional tissue bioprinting can also offer a solution to this problem, as all cellular elements of skin tissue can be used, and with the help of appropriate hydrogels and bioinks, complex structures can be created that can provide a complete functional repertoire of the skin. It is important not just in the clinical therapeutic use, but it can also trigger the replacement of animal models and a number of toxicological studies in preclinical trials. Orv Hetil. 2022; 163(10): 375–385.

High salt diet impairs dermal tissue remodeling in a mouse model of IMQ induced dermatitis

Recent animal studies, as well as quantitative sodium MRI observations on humans demonstrated that remarkable amounts of sodium can be stored in the skin. It is also known that excess sodium in the tissues leads to inflammation in various organs, but its role in dermal pathophysiology has not been elucidated. Therefore, our aim was to study the effect of dietary salt loading on inflammatory process and related extracellular matrix (ECM) remodeling in the skin. To investigate the effect of high salt consumption on inflammation and ECM production in the skin mice were kept on normal (NSD) or high salt (HSD) diet and then dermatitis was induced with imiquimod (IMQ) treatment. The effect of high salt concentration on dermal fibroblasts (DF) and peripheral blood mononuclear cells (PBMC) was also investigated in vitro. The HSD resulted in increased sodium content in the skin of mice. Inflammatory cytokine Il17 expression was elevated in the skin of HSD mice. Expression of anti-inflammatory Il10 and Il13 decreased in the skin of HSD or HSD IMQ mice. The fibroblast marker Acta2 and ECM component Fn and Col1a1 decreased in HSD IMQ mice. Expression of ECM remodeling related Pdgfb and activation phosphorylated (p)-SMAD2/3 was lower in HSD IMQ mice. In PBMCs, production of IL10, IL13 and PDGFB was reduced due to high salt loading. In cultured DFs high salt concentration resulted in decreased cell motility and ECM production, as well. Our results demonstrate that high dietary salt intake is associated with increased dermal pro-inflammatory status. Interestingly, although inflammation induces the synthesis of ECM in most organs, the expression of ECM decreased in the inflamed skin of mice on high salt diet. Our data suggest that salt intake may alter the process of skin remodeling.

Mouse organoid culture is a suitable model to study esophageal ion transport mechanisms

Altered esophageal ion transport mechanisms play a key role in inflammatory and cancerous diseases of the esophagus, but epithelial ion processes have been less studied in the esophagus because of the lack of a suitable experimental model. In this study, we generated three-dimensional (3D) esophageal organoids (EOs) from two different mouse strains and characterized the ion transport processes of the EOs. EOs form a cell-filled structure with a diameter of 250-300 µm and were generated from epithelial stem cells as shown by FACS analysis. Using conventional PCR and immunostaining, the presence of Slc26a6 Cl-/HCO3- anion exchanger (AE), Na+/H+ exchanger (NHE), Na+/HCO3- cotransporter (NBC), cystic fibrosis transmembrane conductance regulator (CFTR), and anoctamin 1 Cl- channels was detected in EOs. Microfluorimetric techniques revealed high NHE, AE, and NBC activities, whereas that of CFTR was relatively low. In addition, inhibition of CFTR led to functional interactions between the major acid-base transporters and CFTR. We conclude that EOs provide a relevant and suitable model system for studying the ion transport mechanisms of esophageal epithelial cells, and they can be also used as preclinical tools to assess the effectiveness of novel therapeutic compounds in esophageal diseases associated with altered ion transport processes.

IL-36α and Lipopolysaccharide Cooperatively Induce Autophagy by Triggering Pro-Autophagic Biased Signaling

Autophagy is an intracellular catabolic process that controls infections both directly and indirectly via its multifaceted effects on the innate and adaptive immune responses. It has been reported that LPS stimulates this cellular process, whereas the effect of IL-36α on autophagy remains largely unknown. We therefore investigated how IL-36α modulates the endogenous and LPS-induced autophagy in THP-1 cells. The levels of LC3B-II and autophagic flux were determined by Western blotting. The intracellular localization of LC3B was measured by immunofluorescence assay. The activation levels of signaling pathways implicated in autophagy regulation were evaluated by using a phosphokinase array. Our results showed that combined IL-36α and LPS treatment cooperatively increased the levels of LC3B-II and Beclin-1, stimulated the autophagic flux, facilitated intracellular redistribution of LC3B, and increased the average number of autophagosomes per cell. The IL36α/LPS combined treatment increased phosphorylation of STAT5a/b, had minimal effect on the Akt/PRAS40/mTOR pathway, and reduced the levels of phospho-Yes, phospho-FAK, and phospho-WNK1. Thus, this cytokine/PAMP combination triggers pro-autophagic biased signaling by several mechanisms and thus cooperatively stimulates the autophagic cascade. An increased autophagic activity of innate immune cells simultaneously exposed to IL-36α and LPS may play an important role in the pathogenesis of Gram-negative bacterial infections.

Phenotypic plasticity of melanocytes derived from human adult skin

We previously described a novel in vitro culture technique for dedifferentiated human adult skin melanocytes. Melanocytes cultured in a defined, cholera toxin and PMA free medium became bipolar, unpigmented, and highly proliferative. Furthermore, TRP-1 and c-Kit expression disappeared and EGFR receptor and nestin expression were induced in the cells. Here, we further characterized the phenotype of these dedifferentiated cells and by comparing them to mature pigmented melanocytes we detected crucial steps in their phenotype change. Our data suggest that normal adult melanocytes easily dedifferentiate into pluripotent stem cells given the right environment. This dedifferentiation process described here for normal melanocyte is very similar to what has been described for melanoma cells, indicating that phenotype switching driven by environmental factors is a general characteristic of melanocytes that can occur independent of malignant transformation.

MSC-like cells increase ability of monocyte-derived dendritic cells to polarize IL-17-/IL-10-producing T cells via CTLA-4

Mesenchymal stromal cell-like (MSCl) cells generated from human embryonic stem cells are considered to be an eligible cell line to model the immunomodulatory behavior of mesenchymal stromal cells (MSCs) in vitro. Dendritic cells (DCs) are essential players in the maintenance and restoration of the sensitive balance between tolerance and immunity. Here, the effects of MSCl cells on the in vitro differentiation of human monocytes into DCs were investigated. MSCl cells promote the differentiation of CTLA-4 expressing DCs via the production of all-trans retinoic acid (ATRA) functioning as a ligand of RARα, a key nuclear receptor in DC development. These semi-matured DCs exhibit an ability to activate allogeneic, naive T cells and polarize them into IL-10 + IL-17 + double-positive T helper cells in a CTLA-4-dependent manner. Mapping the molecular mechanisms of MSC-mediated indirect modulation of DC differentiation may help to expand MSCs' clinical application in cell-free therapies.

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Mesenchymal stromal cell-like cells alter moDC differentiation via RARα activation

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Mesenchymal stromal cell-like cells express genes known to play role in ATRA synthesis

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MoDCs, differentiated in the presence of MSCl-derived factors, express CTLA-4

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CTLA-4⁺ moDCs are able to induce polarization of IL-10- and IL-17-producing helper T cells

Bile accelerates carcinogenic processes in pancreatic ductal adenocarcinoma cells through the overexpression of MUC4

Pancreatic cancer (PC) is one of the leading causes of mortality rate globally and is usually associated with obstructive jaundice (OJ). Up to date, there is no clear consensus on whether biliary decompression should be performed prior to surgery and how high levels of serum bile affects the outcome of PC. Therefore, our study aims were to characterise the effect of bile acids (BAs) on carcinogenic processes using pancreatic ductal adenocarcinoma (PDAC) cell lines and to investigate the underlying mechanisms. Liquid chromatography-mass spectrometry was used to determine the serum concentrations of BAs. The effects of BAs on tumour progression were investigated using different assays. Mucin expressions were studied in normal and PDAC cell lines and in human samples at gene and protein levels and results were validated with gene silencing. The levels of BAs were significantly higher in the PDAC + OJ group compared to the healthy control. Treating PDAC cells with different BAs or with human serum obtained from PDAC + OJ patients enhanced the rate of proliferation, migration, adhesion, colony forming, and the expression of MUC4. In PDAC + OJ patients, MUC4 expression was higher and the 4-year survival rate was lower compare to PDAC patients. Silencing of MUC4 decreased BAs-induced carcinogenic processes in PDAC cells. Our results show that BAs promote carcinogenic process in PDAC cells, in which the increased expression of MUC4 plays an important role. Based on these results, we assume that in PC patients, where the disease is associated with OJ, the early treatment of biliary obstruction improves life expectancy.

Cytotoxic activity of human dendritic cells induces RIPK1-dependent cell death

Dendritic cells (DCs), as potent phagocytes engulf dead cells and present peptide fragments of tumor antigens or pathogens derived from infected cells to naïve CD8⁺ T-lymphocytes. Dendritic cells can also induce apoptosis in target cells, thus getting an opportunity to sample their microenvironment. Here, we present that the supernatants of LPS- or CL075-activated DCs induced cell death in different cell lines, but during the differentiation to mature DCs, they lost their cytotoxic potential. Dexamethasone-pre-treated tolerogenic DCs induced less intensive death indicating that the tissue microenvironment can downregulate DC-mediated killing. Exploring the signaling of DC-induced cell death, we observed that the supernatant of activated DCs induced TNF-dependent cell death, since TNF antagonist blocked the cytotoxic activity of DCs, contrary to inhibitors of Fas and TRAIL receptors. We identified that the DC-induced killing is at least partially a RIPK1-dependent process, as RIPK1 positive target cells were more susceptible to DC-induced cell death than their RIPK1 deficient counterparts. Moreover, both the elevated phosphorylation of RIPK1 and the increase in RIPK1-caspase-8 interaction in target cells suggest that RIPK1-mediated signals contribute to DC supernatant-induced cell death. We also proved that the cytotoxic activity of DC-derived supernatant induced apoptosis in the target cells and not necroptosis, as it was completely abrogated with the pan caspase inhibitor (Z-VAD), while the necroptosis inhibitor (Nec-1) had no effect. Our work revealed that the supernatant of activated DCs induces the apoptosis of target cells in a RIPK1-dependent manner. This phenomenon could be relevant for the initiation of cross-presentation and may broaden the plethora of cytotoxic mechanisms acting against tumor cells.

Cyclooxygenase-2 Modulates Glycosaminoglycan Production in the Skin During Salt Overload

Sodium (Na⁺) can accumulate in the skin tissue, sequestered by negatively charged glycosaminoglycans (GAGs). During dietary salt overload, the amount and charge density of dermal GAG molecules - e.g., hyaluronic acid (HA) and chondroitin sulfate (CS) - increases; however, the regulation of the process is unknown. Previously, it has been demonstrated that the level of cyclooxygenase-2 (COX-2) activity and the content of prostaglandin E2 (PGE2) are elevated in the skin due to high-salt consumption. A link between the COX-2/PGE2 system and GAG synthesis was also suggested. We hypothesized that in dermal fibroblasts (DFs) high-sodium concentration activates the COX-2/PGE2 pathway and also that PGE2 increases the production of HA. Our further aim was to demonstrate that the elevation of the GAG content is ceased by COX-2 inhibition in a salt overloaded animal model. For this, we investigated the messenger RNA (mRNA) expression of COX-2 and HA synthase 2 enzymes as well as the PGE2 and HA production of DFs by real-time reverse transcription PCR (qRT-PCR) and ELISA, respectively. The results showed that both high-sodium concentration and PGE2 treatment increases HA content of the media. Sodium excess activates the COX-2/PGE2 pathway in DFs, and COX-2 inhibition decreases the synthesis of HA. In the animal experiment, the HA- and CS disaccharide content in the skin of male Wistar rats was measured using high performance liquid chromatography-mass spectrometry (HPLC-MS). In the skin of rats receiving high-salt diet, the content of both HA- and monosulfated-CS disaccharides increased, whereas COX-2 inhibition blocked this overproduction. In conclusion, high-salt environment could induce GAG production of DFs in a COX-2/PGE2-dependent manner. Moreover, the COX-2 inhibition resulted in a decreased skin GAG content of the salt overloaded rats. These data revealed a new DF-mediated regulation of GAG synthesis in the skin during salt overload.

Regulation of RLR-Mediated Antiviral Responses of Human Dendritic Cells by mTOR

To detect replicating viruses, dendritic cells (DCs) utilize cytoplasmic retinoic acid inducible gene-(RIG) I-like receptors (RLRs), which play an essential role in the subsequent activation of antiviral immune responses. In this study, we aimed to explore the role of the mammalian target of rapamycin (mTOR) in the regulation of RLR-triggered effector functions of human monocyte-derived DCs (moDCs) and plasmacytoid DCs (pDCs). Our results show that RLR stimulation increased the phosphorylation of the mTOR complex (mTORC) 1 and mTORC2 downstream targets p70S6 kinase and Akt, respectively, and this process was prevented by the mTORC1 inhibitor rapamycin as well as the dual mTORC1/C2 kinase inhibitor AZD8055 in both DC subtypes. Furthermore, inhibition of mTOR in moDCs impaired the RLR stimulation-triggered glycolytic switch, which was reflected by the inhibition of lactate production and downregulation of key glycolytic genes. Blockade of mTOR diminished the ability of RLR-stimulated moDCs and pDCs to secret type I interferons (IFNs) and pro-inflammatory cytokines, while it did not affect the phenotype of DCs. We also found that mTOR blockade decreased the phosphorylation of Tank-binding kinase 1 (TBK1), which mediates RLR-driven cytokine production. In addition, rapamycin abrogated the ability of both DC subtypes to promote the proliferation and differentiation of IFN-y and Granzyme B producing CD8 + T cells. Interestingly, AZD8055 was much weaker in its ability to decrease the T cell proliferation capacity of DCs and was unable to inhibit the DC-triggered production of IFN-y and Granyzme B by CD8 + T cells. Here we demonstrated for the first time that mTOR positively regulates the RLR-mediated antiviral activity of human DCs. Further, we show that only selective inhibition of mTORC1 but not dual mTORC1/C2 blockade suppresses effectively the T cell stimulatory capacity of DCs that should be considered in the development of new generation mTOR inhibitors and in the improvement of DC-based vaccines.

Osteogenic differentiation of human bone marrow-derived mesenchymal stem cells is enhanced by an aragonite scaffold

Bone graft substitutes and bone void fillers are predominantly used to treat bone defects and bone fusion in orthopaedic surgery. Some aragonite-based scaffolds of coralline exoskeleton origin exhibit osteoconductive properties and are described as useful bone repair scaffolds. The purpose of this study was to evaluate the in vitro osteogenic potential of the bone phase of a novel aragonite-based bi-phasic osteochondral scaffold (Agili-C™, CartiHeal Ltd.) using adult human bone marrow-derived mesenchymal stem cells (MSCs). Analyses were performed at several time intervals: 3, 7, 14, 21, 28 and 42 days post-seeding. Osteogenic differentiation was assessed by morphological characterisation using light microscopy after Alizarin red and von Kossa staining, and scanning electron microscopy. The transcript levels of alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), bone gamma-carboxyglutamate (BGLAP), osteonectin (SPARC) and osteopontin (SPP1) were determined by quantitative PCR. Proliferation was assessed by a thymidine incorporation assay and proliferating cell nuclear antigen (PCNA) immunocytochemistry. Our results demonstrate that the bone phase of the bi-phasic aragonite-based scaffold supports osteogenic differentiation and enhanced proliferation of bone marrow-derived MSCs at both the molecular and histological levels. The scaffold was colonized by differentiating MSCs, suggesting its suitability for incorporation into bone voids to accelerate bone healing, remodelling and regeneration. The mechanism of osteogenic differentiation involves scaffold surface modification with de novo production of calcium phosphate deposits, as revealed by energy dispersive spectroscopy (EDS) analyses. This novel coral-based scaffold may promote the rapid formation of high quality bone during the repair of osteochondral lesions.

Differentiating SGBS adipocytes respond to PPARγ stimulation, irisin and BMP7 by functional browning and beige characteristics

Brown and beige adipocytes are enriched in mitochondria with uncoupling protein-1 (UCP1) to generate heat instead of ATP contributing to healthy energy balance. There are few human cellular models to reveal regulatory networks in adipocyte browning and key targets for enhancing thermogenesis in obesity. The Simpson-Golabi-Behmel syndrome (SGBS) preadipocyte line has been a useful tool to study human adipocyte biology. Here we report that SGBS cells, which are comparable to subcutaneous adipose-derived stem cells, carry an FTO risk allele. Upon sustained PPARγ stimulation or irisin (a myokine released in response to exercise) treatment, SGBS cells differentiated into beige adipocytes exhibiting multilocular lipid droplets, high UCP1 content with induction of typical browning genes (Cidea, Elovl3) and the beige marker Tbx1. The autocrine mediator BMP7 led to moderate browning with the upregulation of the classical brown marker Zic1 instead of Tbx1. Thermogenesis potential resulted from PPARγ stimulation, irisin and BMP7 can be activated in UCP1-dependent and the beige specific, creatine phosphate cycle mediated way. The beige phenotype, maintained under long-term (28 days) conditions, was partially reversed by withdrawal of PPARγ ligand. Thus, SGBS cells can serve as a cellular model for both white and sustainable beige adipocyte differentiation and function.

Human Embryonic Stem Cell-Derived Retinal Pigment Epithelium-Role in Dead Cell Clearance and Inflammation

Inefficient removal of dying retinal pigment epithelial (RPE) cells by professional phagocytes can result in debris formation and development of age-related macular degeneration (AMD). Chronic oxidative stress and inflammation play an important role in AMD pathogenesis. Only a few well-established in vitro phagocytosis assay models exist. We propose human embryonic stem cell-derived-RPE cells as a new model for studying RPE cell removal by professional phagocytes. The characteristics of human embryonic stem cells-derived RPE (hESC-RPE) are similar to native RPEs based on their gene and protein expression profile, integrity, and barrier properties or regarding drug transport. However, no data exist about RPE death modalities and how efficiently dying hESC-RPEs are taken upby macrophages, and whether this process triggers an inflammatory responses. This study demonstrates hESC-RPEs can be induced to undergo anoikis or autophagy-associated cell death due to extracellular matrix detachment or serum deprivation and hydrogen-peroxide co-treatment, respectively, similar to primary human RPEs. Dying hESC-RPEs are efficiently engulfed by macrophages which results in high amounts of IL-6 and IL-8 cytokine release. These findings suggest that the clearance of anoikic and autophagy-associated dying hESC-RPEs can be used as a new model for investigating AMD pathogenesis or for testing the in vivo potential of these cells in stem cell therapy.

Ex vivo 3D human corneal stroma model for Schnyder corneal dystrophy - role of autophagy in its pathogenesis and resolution

INTRODUCTION

Multilamellar bodies (MLBs) are concentric cytoplasmic membranes which form through an autophagy-dependent mechanism. In the cornea, the presence of MLBs is associated with Schnyder corneal dystrophy (SCD). Ex vivo 3D modelling of the corneal stroma and SCD can help study pathogenesis and resolution of the disorder.

METHODS

Corneal stroma explants were isolated from cadavers and cultivated long-term for more than 3 months to achieve spontaneous 3D outgrowth of corneal stroma-derived mesenchymal stem-like cells (CSMSCs). The 3D tissues were then examined by transmission electron microscopy (TEM) for presence of MLBs, and by immunofluorescent labelling against markers for autophagy (p62, LC3). Autophagy was induced by classical serum starvation or rapamycin (RAP) treatment (50 nM), and inhibited by the autophagy inhibitor 3-methyladenine (3-MA, 10 mM) for 24 hours.

RESULTS

CSMSCs can form spontaneously 3D outgrowths over a 3-4 weeks period, depositing their own extracellular matrix containing collagen I. TEM confirmed the presence of MLBs in the long-term (>3 months) 3D cultures, which became more abundant under starvation and RAP treatment, and decreased in number under autophagy inhibition with 3-MA. The presence of autophagy and its disappearance could be confirmed by an inversely related increase and decrease in the expression of LC3 and p62, respectively.

CONCLUSIONS

MLB formation in long-standing CSMSC cultures could serve as a potential ex vivo model for studying corneal stroma diseases, including SCD. Inhibition of autophagy can decrease the formation of MLBs, which may lead to a novel treatment of the disease in the future.

Comparative proteomic analysis of human embryonic stem cell-derived and primary human retinal pigment epithelium

Human embryonic stem cell-derived retinal pigment epithelial cells (hESC-RPE) provide an unlimited cell source for retinal cell replacement therapies. Clinical trials using hESC-RPE to treat diseases such as age-related macular degeneration (AMD) are currently underway. Human ESC-RPE cells have been thoroughly characterized at the gene level but their protein expression profile has not been studied at larger scale. In this study, proteomic analysis was used to compare hESC-RPE cells differentiated from two independent hESC lines, to primary human RPE (hRPE) using Isobaric tags for relative quantitation (iTRAQ). 1041 common proteins were present in both hESC-RPE cells and native hRPE with majority of the proteins similarly regulated. The hESC-RPE proteome reflected that of normal hRPE with a large number of metabolic, mitochondrial, cytoskeletal, and transport proteins expressed. No signs of increased stress, apoptosis, immune response, proliferation, or retinal degeneration related changes were noted in hESC-RPE, while important RPE specific proteins involved in key RPE functions such as visual cycle and phagocytosis, could be detected in the hESC-RPE. Overall, the results indicated that the proteome of the hESC-RPE cells closely resembled that of their native counterparts.

Cultivation and characterization of pterygium as an ex vivo study model for disease and therapy

PURPOSE

Development of ex vivo model to study pathogenesis, inflammation and treatment modalities for pterygium.

METHODS

Pterygium obtained from surgery was cultivated (3 months). Gravitational attachment method using viscoelastic facilitated adherence of graft and outgrowing cells. Medium contained serum as the only growth supplement with no use of scaffolds. Surface profiling of the multi-layered cells for hematopoietic- and mesenchymal stem cell markers was performed. Examination of cells by immunohistochemistry using pluripotency, oxidative stress, stemness, migration and proliferation, epithelial and secretory markers was performed. The effect of anti-proliferative agent Mitomycin C upon secretion of pro-inflammatory cytokines IL-6 and IL-8 was assessed.

RESULTS

Cells showed high expression of migration- (CXCR4), secretory- (MUC1, MUC4) and oxidative damage- (8-OHdG) markers, and low expression of hypoxia- (HIF-1α) and proliferation- (Ki-67) markers. Moderate and low expression of the pluripotency markers (Vimentin and ΔNp63) was present, respectively, while the putative markers of stemness (Sox2, Oct4, ABCG-2) and epithelial cell markers- (CK19, CK8-18) were weak. The surface marker profile of the outgrowing cells revealed high expression of the hematopoietic marker CD47, mesenchymal markers CD90 and CD73, minor or less positivity for the hematopoietic marker CD34, mesenchymal marker CD105, progenitor marker CD117 and attachment protein markers while low levels of IL-6 and IL-8 secretion ex vivo, were inhibited upon Mitomycin C treatment.

CONCLUSION

Ex vivo tissue engineered pterygium consists of a mixture of cells of different lineage origin, suitable for use as a disease model for studying pathogenesis ex vivo, while opening possibilities for new treatment and prevention modalities.

Cultivation and characterisation of the surface markers and carbohydrate profile of human corneal endothelial cells

BACKGROUND

The study aims to characterise human corneal endothelial cell (HCEnC) cultures generated by the peel-and-digest method based on their surface protein/carbohydrate expression pattern.

METHODS

Quantitative polymerase chain reaction was used to compare expression of vimentin, CD90, Cytokeratin-19, ZO-1 and Claudin 14 in cultured HCEnC and cell line B4G12 versus stromal cells. Fluorescence-activated cell sorting was used to assess surface protein distribution of cultured and uncultured HCEnC. Distribution of surface proteins/carbohydrates was visualised by immunofluorescent and lectin staining.

RESULTS

Human corneal endothelial cell and B4G12 showed lower expression level for vimentin, CD90, Cytokeratin-19 compared with stromal cells; while ZO-1 was expressed in endothelial cells, Claudin 14 was detected in B4G12 only. Fluorescence-activated cell sorting analyses revealed CD166, CD47, CD44, CD54, CD73, CD90, CD105, CD106, CD112, CD146 and CD325 to be present, with CD34 to be absent from cultured HCEnC. Freshly isolated, non-cultivated HCEnCs were CD90, CD73, CD146 and CD325 positive. Carbohydrates were detected by lectins LCA, PHA E, PHA L, PSA, sWGA, Con A, RCA 120 and WGA, but cultured HCEnC showed negative for GSL I, SBA, DBA, PNA and UEA I.

CONCLUSION

Cultures established by the peel-and-digest method are probably not prone to stromal contamination, but the cells are likely to undergo endothelial-to mesenchymal transition as suggested by apparent morphological changes.

Nitric oxide-coupled signaling in odor elicited molecular events in the olfactory center of the terrestrial snail, Helix pomatia

Olfaction, a chemosensory modality, plays a pivotal role in the orientation and behavior of invertebrates. The central olfactory processing unit in terrestrial stylomatophoran snails is the procerebrum, which contains NO synthesizing interneurons, whose oscillatory currents are believed to be the base of odor evoked memory formation. Nevertheless, in this model the up- and downstream events of molecular cascades that trigger and follow NO release, respectively, have not been studied. Immunocytochemistry and flow cytometry studies performed on procerebral neural perikarya isolated from the snail Helix pomatia revealed cell populations with discrete DAF-2 fluorescence, indicating the release of different amounts of NO. Glutamate increased the intensity of DAF-2 fluorescence, and the number of DAF-2 positive non-bursting interneurons, through a mechanism likely to involve an NMDA-like receptor. Similarly to glutamate, NO activation induced an increase in intracellular cGMP levels through activation of soluble guanylyl cyclase. Immunohistochemical localization of proteins possessing the phosphorylated target sequence of AGC family kinases (RXXS/T-P), among them protein kinase A (RRXS/T-P), showed striking similarities to the distribution of NOS/cGMP. Activators of cyclic nucleotide synthesis increased the AGC-kinase-dependent phosphorylation of discrete proteins with 28, 45, and 55kDamw. Importantly, exposure of snails to an attractive odorant induced hyperphosphorylation of the 28kDa protein, and increased levels of cGMP synthesis. Protein S-nitrosylation and intercellular activation of protein kinase G were also suggested as alternative components of NO signaling in the snail procerebrum. The present results from Helix pomatia indicate an important role for procerebrum NO/cGMP/PKA signaling pathways in the regulation of olfactory (food-finding) behavior.

Role of Human Corneal Stroma-Derived Mesenchymal-Like Stem Cells in Corneal Immunity and Wound Healing

Corneal tissue regeneration is of crucial importance for maintaining normal vision. We aimed to isolate and cultivate human corneal stroma-derived mesenchymal stem-like cells (CSMSCs) from the central part of cadaver corneas and study their phenotype, multipotency, role in immunity and wound healing. The isolated cells grew as monolayers in vitro, expressed mesenchymal- and stemness-related surface markers (CD73, CD90, CD105, CD140b), and were negative for hematopoietic markers as determined by flow cytometry. CSMSCs were able to differentiate in vitro into fat, bone and cartilage. Their gene expression profile was closer to bone marrow-derived MSCs (BMMSCs) than to limbal epithelial stem cells (LESC) as determined by high-throughput screening. The immunosuppressive properties of CSMSCs were confirmed by a mixed lymphocyte reaction (MLR), while they could inhibit proliferation of activated immune cells. Treatment of CSMSCs by pro-inflammatory cytokines and toll-like receptor ligands significantly increased the secreted interleukin-6 (IL-6), interleukin-8 (IL-8) and C-X-C motif chemokine 10 (CXCL-10) levels, as well as the cell surface adhesion molecules. CSMSCs were capable of closing a wound in vitro under different stimuli. These cells thus contribute to corneal tissue homeostasis and play an immunomodulatory and regenerative role with possible implications in future cell therapies for treating sight-threatening corneal diseases.

Comparative proteomics reveals human pluripotent stem cell-derived limbal epithelial stem cells are similar to native ocular surface epithelial cells

Limbal epithelial stem cells (LESCs) are tissue-specific stem cells responsible for renewing the corneal epithelium. Acute trauma or chronic disease affecting LESCs may disrupt corneal epithelial renewal, causing vision threatening and painful ocular surface disorders, collectively referred to as LESC deficiency (LESCD). These disorders cannot be treated with traditional corneal transplantation and therefore alternative cell sources for successful cell-based therapy are needed. LESCs derived from human pluripotent stem cells (hPSCs) are a prospective source for ocular surface reconstruction, yet critical evaluation of these cells is crucial before considering clinical applications. In order to quantitatively evaluate hPSC-derived LESCs, we compared protein expression in native human corneal cells to that in hPSC-derived LESCs using isobaric tag for relative and absolute quantitation (iTRAQ) technology. We identified 860 unique proteins present in all samples, including proteins involved in cell cycling, proliferation, differentiation and apoptosis, various LESC niche components, and limbal and corneal epithelial markers. Protein expression profiles were nearly identical in LESCs derived from two different hPSC lines, indicating that the differentiation protocol is reproducible, yielding homogeneous cell populations. Their protein expression profile suggests that hPSC-derived LESCs are similar to the human ocular surface epithelial cells, and possess LESC-like characteristics.

Enhanced regeneration of corneal tissue via a bioengineered collagen construct implanted by a nondisruptive surgical technique

Severe shortage of donor corneas for transplantation, particularly in developing countries, has prompted the advancement of bioengineered tissue alternatives. Bioengineered corneas that can withstand transplantation while maintaining transparency and compatibility with host cells, and that are additionally amenable to standardized low-cost mass production are sought. In this study, a bioengineered porcine construct (BPC) was developed to function as a biodegradable scaffold to promote corneal stromal regeneration by host cells. Using high-purity medical-grade type I collagen, high 18% collagen content and optimized EDC-NHS cross-linker ratio, BPCs were fabricated into hydrogel corneal implants with over 90% transparency and four-fold increase in strength and stiffness compared with previous versions. Remarkably, optical transparency was achieved despite the absence of collagen fibril organization at the nanoscale. In vitro testing indicated that BPC supported confluent human epithelial and stromal-derived mesenchymal stem cell populations. With a novel femtosecond laser-assisted corneal surgical model in rabbits, cell-free BPCs were implanted in vivo in the corneal stroma of 10 rabbits over an 8-week period. In vivo, transparency of implanted corneas was maintained throughout the postoperative period, while healing occurred rapidly without inflammation and without the use of postoperative steroids. BPC implants had a 100% retention rate at 8 weeks, when host stromal cells began to migrate into implants. Direct histochemical evidence of stromal tissue regeneration was observed by means of migrated host cells producing new collagen from within the implants. This study indicates that a cost-effective BPC extracellular matrix equivalent can incorporate cells passively to initiate regenerative healing of the corneal stroma, and is compatible with human stem or organ-specific cells for future therapeutic applications as a stromal replacement for treating blinding disorders of the cornea.

Triamcinolone regulated apopto-phagocytic gene expression patterns in the clearance of dying retinal pigment epithelial cells. A key role of Mertk in the enhanced phagocytosis

BACKGROUND

The apopto-phagocytic gene expression patterns during clearance of dying cells in the retina and the effect of triamcinolone (TC) upon these processes have relevance to development of age-related macular degeneration (AMD).

METHODS

ARPE-19 cells and primary human retinal pigment epithelium (hRPE) were induced to undergo cell death by anoikis and the clearance of these cells by living hRPE/ARPE-19 or human monocyte-derived macrophages (HMDMs) in the presence or absence of TC was quantified by flow cytometry. TaqMan low-density gene expression array determining known markers of phagocytosis and loss-of-function studies on selected apopto-phagocytic genes was carried out in HMDM engulfing anoikic cells.

RESULTS

The glucocorticoid TC had a profound phagocytosis-enhancing effect on HMDM engulfing anoikic ARPE-19 or hRPE cells, causing a selective upregulation of the Mer tyrosine kinase (MERTK) receptor, while decreasing the expression of the AXL receptor tyrosine kinase and thrombospondin-1 (THSB-1). The key role of the MERTK could be demonstrated in HMDM engulfing dying cells using gene silencing as well as blocking antibodies. Similar pathways were found upregulated in living ARPE-19 engulfing anoikic ARPE-19 cells. Gas6 treatment enhanced phagocytosis in TC-treated HMDMs.

CONCLUSIONS

Specific agonists of the Mertk receptor may have a potential role as phagocytosis enhancers in the retina and serve as future targets for AMD therapy.

GENERAL SIGNIFICANCE

The use of Gas6 as enhancer of retinal phagocytosis via the MerTK receptor, alone or in combination with other specific ligands of the tyrosine kinase receptors' family may have a potential role in AMD therapy.

Atypical antipsychotics induce both proinflammatory and adipogenic gene expression in human adipocytes in vitro

Schizophrenia requires lifelong treatment, potentially causing systemic changes in metabolic homeostasis. In the clinical setting, antipsychotic treatment may differentially lead to weight gain among individual patients, although the molecular determinants of such adverse effects are currently unknown. In this study, we investigated changes in the expression levels of critical regulatory genes of adipogenesis, lipid metabolism and proinflammatory genes during the differentiation of primary human adipose-derived stem cells (ADSCs). These cells were isolated from patients with body mass indices <25 and treated with the second-generation antipsychotics olanzapine, ziprasidone, clozapine, quetiapine, aripiprazole and risperidone and the first-generation antipsychotic haloperidol. We found that antipsychotics exhibited a marked effect on key genes involved in the regulation of cell cycle, signal transduction, transcription factors, nuclear receptors, differentiation markers and metabolic enzymes. In particular, we observed an induction of the transcription factor NF-KB1 and NF-KB1 target genes in adipocytes in response to these drugs, including the proinflammatory cytokines TNF-α, IL-1β, IL-8 and MCP-1. In addition, enhanced secretion of both IL8 and MCP-1 was observed in the supernatant of these cell cultures. In addition to their remarkable stimulatory effects on proinflammatory gene transcription, three of the most frequently prescribed antipsychotic drugs, clozapine, quetiapine and aripiprazole, also induced the expression of essential adipocyte differentiation genes and the adipocyte hormones leptin and adiponectin, suggesting that both glucose and fat metabolism may be affected by these drugs. These data further suggest that antipsychotic treatments in patients alter the gene expression patterns in adipocytes in a coordinated fashion and priming them for a low-level inflammatory state.

Estrogen signalling in the pathogenesis of age-related macular degeneration

Age-related macular degeneration (AMD) is a multifactorial eye disease that is associated with aging, family history, smoking, obesity, cataract surgery, arteriosclerosis, hypertension, hypercholesterolemia and unhealthy diet. Gender has commonly been classified as a weak or inconsistent risk factor for AMD. This disease is characterized by degeneration of retinal pigment epithelial (RPE) cells, Bruch's membrane, and choriocapillaris, which secondarily lead to damage and death of photoreceptor cells and central visual loss. Pathogenesis of AMD involves constant oxidative stress, chronic inflammation, and increased accumulation of lipofuscin and drusen. Estrogen has both anti-oxidative and anti-inflammatory capacity and it regulates signaling pathways that are involved in the pathogenesis of AMD. In this review, we discuss potential cellular signaling targets of estrogen in retinal cells and AMD pathology.

Comparison of upstream regulators in human ex vivo cultured cornea limbal epithelial stem cells and differentiated corneal epithelial cells

Background

The surface of the human eye is covered by corneal epithelial cells (CECs) which regenerate from a small population of limbal epithelial stem cells (LESCs). Cell therapy with LESCs is a non-penetrating treatment for preventing blindness due to LESC deficiency or dysfunction. Our aim was to identify new putative molecular markers and upstream regulators in the LESCs and associated molecular pathways.

Results

Genome-wide microarray transcriptional profiling was used to compare LESCs to differentiated human CECs. Ingenuity-based pathway analysis was applied to identify upstream regulators and pathways specific to LESCs. ELISA and flow cytometry were used to measure secreted and surface expressed proteins, respectively. More than 2 fold increase and decrease in expression could be found in 1830 genes between the two cell types. A number of molecules functioning in cellular movement (381), proliferation (567), development (552), death and survival (520), and cell-to-cell signaling (290) were detected having top biological functions in LESCs and several of these were confirmed by flow cytometric surface protein analysis. Custom-selected gene groups related to stemness, differentiation, cell adhesion, cytokines and growth factors as well as angiogenesis could be analyzed. The results show that LESCs play a key role not only in epithelial differentiation and tissue repair, but also in controlling angiogenesis and extracellular matrix integrity. Some pro-inflammatory cytokines were found to be important in stemness-, differentiation- and angiogenesis-related biological functions: IL-6 and IL-8 participated in most of these biological pathways as validated by their secretion from LESC cultures.

Conclusions

The gene and molecular pathways may provide a more specific understanding of the signaling molecules associated with LESCs, therefore, help better identify and use these cells in the treatment of ocular surface diseases.

Functional and molecular characterization of ex vivo cultured epiretinal membrane cells from human proliferative diabetic retinopathy

Characterization of the cell surface marker phenotype of ex vivo cultured cells growing out of human fibrovascular epiretinal membranes (fvERMs) from proliferative diabetic retinopathy (PDR) can give insight into their function in immunity, angiogenesis, and retinal detachment. FvERMs from uneventful vitrectomies due to PDR were cultured adherently ex vivo. Surface marker analysis, release of immunity- and angiogenesis-pathway-related factors upon TNF α activation and measurement of the intracellular calcium dynamics upon mechano-stimulation using fluorescent dye Fura-2 were all performed. FvERMs formed proliferating cell monolayers when cultured ex vivo, which were negative for endothelial cell markers (CD31, VEGFR2), partially positive for hematopoietic- (CD34, CD47) and mesenchymal stem cell markers (CD73, CD90/Thy-1, and PDGFR β ), and negative for CD105. CD146/MCAM and CD166/ALCAM, previously unreported in cells from fvERMs, were also expressed. Secretion of 11 angiogenesis-related factors (DPPIV/CD26, EG-VEGF/PK1, ET-1, IGFBP-2 and 3, IL-8/CXCL8, MCP-1/CCL2, MMP-9, PTX3/TSG-14, Serpin E1/PAI-1, Serpin F1/PEDF, TIMP-1, and TSP-1) were detected upon TNF α activation of fvERM cells. Mechano-stimulation of these cells induced intracellular calcium propagation representing functional viability and role of these cells in tractional retinal detachment, thus serving as a model for studying tractional forces present in fvERMs in PDR ex vivo.

Autophagy and heterophagy dysregulation leads to retinal pigment epithelium dysfunction and development of age-related macular degeneration

Age-related macular degeneration (AMD) is a complex, degenerative and progressive eye disease that usually does not lead to complete blindness, but can result in severe loss of central vision. Risk factors for AMD include age, genetics, diet, smoking, oxidative stress and many cardiovascular-associated risk factors. Autophagy is a cellular housekeeping process that removes damaged organelles and protein aggregates, whereas heterophagy, in the case of the retinal pigment epithelium (RPE), is the phagocytosis of exogenous photoreceptor outer segments. Numerous studies have demonstrated that both autophagy and heterophagy are highly active in the RPE. To date, there is increasing evidence that constant oxidative stress impairs autophagy and heterophagy, as well as increases protein aggregation and causes inflammasome activation leading to the pathological phenotype of AMD. This review ties together these crucial pathological topics and reflects upon autophagy as a potential therapeutic target in AMD.

Cultivation and characterization of cornea limbal epithelial stem cells on lens capsule in animal material-free medium

A simple, reproducible, animal-material free method for cultivating and characterizing cornea limbal epithelial stem cells (LESCs) on human lens capsule (LC) was developed for future clinical transplantation. The limbal tissue explants (2×2×0.25 mm) were harvested from 77 cadavers and expanded ex vivo on either cell culture plates or LC in medium containing human serum as the only growth supplement. Cell outgrowth at the edge of the explants was observed within 24 hours of cultivation and achieved viable outgrowth (>97% viability as measured by MTT assay and flow cytometry) within two weeks. The outgrowing cells were examined by genome-wide microarray including markers of stemness (p63α, ABCG2, CK19, Vimentin and Integrin α9), proliferation (Ki-67), limbal epithelial cells (CK 8/18 and 14) and differentiated cornea epithelial cells (CK 3 and 12). Immunostaining revealed the non-hematopoietic, -endothelial and -mesenchymal stem cell phenotype of the LESCs and the localization of specific markers in situ. Cell adhesion molecules, integrins and lectin-based surface carbohydrate profiling showed a specific pattern on these cells, while colony-formation assay confirmed their clonal potency. The LESCs expressed a specific surface marker fingerprint (CD117/c-kit, CXCR4, CD144/VE-Cadherin, CD146/MCAM, CD166/ALCAM, and surface carbohydrates: WGA, ConA, RCA, PNA and AIL) which can be used for better localization of the limbal stem cell niche. In summary, we report a novel method combining the use of a medium with human serum as the only growth supplement with LC for cultivating, characterizing and expanding cornea LESCs from cadavers or alternatively from autologous donors for possible treatment of LESC deficiency.

Anti-TNF-alpha antibody (infliximab) therapy supports the recovery of eNOS and VEGFR2 protein expression in endothelial cells

The aim of this study is to investigate the effect of sera obtained from patients of Crohn's disease treated by anti-TNF-alpha antibody (Infliximab) on the expression of endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor receptor-2 (VEGFR2) protein in human umbilical vein endothelial cells (HUVEC) cultured in vitro. HUVEC was cultured in the presence of sera derived from patients before and after treatment, or from healthy individuals. Effects of sera on the expression of eNOS and VEGFR2 were monitored by determination of mRNA and protein levels using real time quantitative PCR and Western blot analysis, respectively. The serum of Crohn's patients contained elevated levels of TNF-alpha (34±1.80 pg/mL), which resulted in a decrease in the protein level of eNOS in HUVEC with a simultaneous induction of VEGFR2. Infliximab treatment normalized the expression level of these proteins by decreasing TNF-alpha level, particularly in those cases when clinical healing was also recorded, and it also conferred restitution of the level of angiogenic cytokines. Results suggest that altered angiogenesis possibly contributes to the initiation and perpetuation of inflammatory processes in inflammatory bowel disease (IBD). Endothelial dysfunction, a selective feature of Crohn's disease is beneficially affected by intravascular TNF-alpha neutralization.

Peroxidasin is secreted and incorporated into the extracellular matrix of myofibroblasts and fibrotic kidney

Mammalian peroxidases are heme-containing enzymes that serve diverse biological roles, such as host defense and hormone biosynthesis. A mammalian homolog of Drosophila peroxidasin belongs to the peroxidase family; however, its function is currently unknown. In this study, we show that peroxidasin is present in the endoplasmic reticulum of human primary pulmonary and dermal fibroblasts, and the expression of this protein is increased during transforming growth factor-beta1-induced myofibroblast differentiation. Myofibroblasts secrete peroxidasin into the extracellular space where it becomes organized into a fibril-like network and colocalizes with fibronectin, thus helping to form the extracellular matrix. We also demonstrate that peroxidasin expression is increased in a murine model of kidney fibrosis and that peroxidasin localizes to the peritubular space in fibrotic kidneys. In addition, we show that this novel pathway of extracellular matrix formation is unlikely mediated by the peroxidase activity of the protein. Our data indicate that peroxidasin secretion represents a previously unknown pathway in extracellular matrix formation with a potentially important role in the physiological and pathological fibrogenic response.

[Autologous bone marrow-derived stem cell therapy in patients with severe peripheral arterial disorder]

BACKGROUND AND AIMS

Amputation is the only current option for relief of rest pain or gangrene in patients with severe peripheral arterial disease. Up to now, no effective blood-flow enhancement therapies are available. Autologous bone marrow-derived stem cell transplantation is an arising therapy modality with an option of building new blood vessels through endothelial stem and/or progenitor cells.

PATIENTS AND METHODS

Five patients with severe peripheral arterial disorder were treated by autologous bone marrow-derived stem cell therapy. CD34+, CD133+ and CD45+/- cell number and ratio were determined. CD34+ cells were isolated by magnetic separation and collected into a 10 ml sample. The cell suspension was administered by local intramuscular injections (0.5-1.0 ml injections in the musculus gastrocnemius). The follow-up (before; 1, 3, 6, 9 and 12 months after the autologous bone marrow-derived stem cell therapy) based on clinical (rest pain, walking distance without pain, changes of non-healing ischaemic ulcers, ankle-brachial index) and laboratory (angiography, Color- and Laser-Doppler scan, measurement of transcutaneous oxygen tension and endothelial function test) parameters was documented and analyzed.

RESULTS

Improvement of pain and walking distance was observed in all five cases. In three cases the non-healing ischaemic ulcers disappeared, in one other case they became smaller and thinner, and in one case no change was realized. The average of ankle-brachial index improved significantly (before: 0.41, twelve months after: 0.83). New collaterals were detected by angiography in three patients, but duplex ultrasonography detected improvement in one patient only. Before and 1, 6 and 12 months after stem cell therapy the transcutaneous oxygen tension changed on the foot from 18.80/16.78/23.83/37.50 mmHg, and on the calf from 36.66/31.25/45.00/37.30 mmHg. The macro- and microcirculation parameters did not show improvement after 1 month, however, after 3, 6, 9 and 12 months improved parameters were recorded. Severe adverse events were not observed. In one case elevated level of serum creatinine phosphokinase, and in another case a mild form of vasculitis were detected.

CONCLUSION

autologous bone marrow-derived stem cell therapy with isolated CD34+ cells is effective, safe and results in sustained clinical benefit for patients with severe peripheral arterial disease.