Prostaglandin E₂ induces oncostatin M expression in human chronic wound macrophages through Axl receptor tyrosine kinase pathway

Pulsed Radiofrequency Electromagnetic Fields as Modulators of Inflammation and Wound Healing in Primary Dermal Fibroblasts of Ulcers

Venous leg ulcers are one of the most common nonhealing conditions and represent an important clinical problem. The application of pulsed radiofrequency electromagnetic fields (PRF-EMFs), already applied for pain, inflammation, and new tissue formation, can represent a promising approach for venous leg ulcer amelioration. This study aims to evaluate the effect of PRF-EMF exposure on the inflammatory, antioxidant, cell proliferation, and wound healing characteristics of human primary dermal fibroblasts collected from venous leg ulcer patients. The cells' proliferative and migratory abilities were evaluated by means of a BrdU assay and scratch assay, respectively. The inflammatory response was investigated through TNFα, TGFβ, COX2, IL6, and IL1β gene expression analysis and PGE2 and IL1β production, while the antioxidant activity was tested by measuring GSH, GSSG, tGSH, and GR levels. This study emphasizes the ability of PRF-EMFs to modulate the TGFβ, COX2, IL6, IL1β, and TNFα gene expression in exposed ulcers. Moreover, it confirms the improvement of the proliferative index and wound healing ability presented by PRF-EMFs. In conclusion, exposure to PRF-EMFs can represent a strategy to help tissue repair, regulating mediators involved in the wound healing process.

Collagenase-based wound debridement agent induces extracellular matrix supporting phenotype in macrophages

Macrophages assume diverse phenotypes and functions in response to cues from the microenvironment. Earlier we reported an anti-inflammatory effect of Collagenase Santyl® Ointment (CSO) and the active constituent of CSO (CS-API) on wound macrophages in resolving wound inflammation indicating roles beyond debridement in wound healing. Building upon our prior finding, this study aimed to understand the phenotypes and subsets of macrophages following treatment with CS-API. scRNA-sequencing was performed on human blood monocyte-derived macrophages (MDM) following treatment with CS-API for 24 h. Unbiased data analysis resulted in the identification of discrete macrophage subsets based on their gene expression profiles. Following CS-API treatment, clusters 3 and 4 displayed enrichment of macrophages with high expression of genes supporting extracellular matrix (ECM) function. IPA analysis identified the TGFβ-1 pathway as a key hub for the CS-API-mediated ECM-supportive phenotype of macrophages. Earlier we reported the physiological conversion of wound-site macrophages to fibroblasts in granulation tissue and impairment of such response in diabetic wounds, leading to compromised ECM and tensile strength. The findings that CSO can augment the physiological conversion of macrophages to fibroblast-like cells carry significant clinical implications. This existing clinical intervention, already employed for wound care, can be readily repurposed to improve the ECM response in chronic wounds.

Nanoscopic and Functional Characterization of Keratinocyte-Originating Exosomes in the Wound Fluid of Non-Diabetic and Diabetic Chronic Wound Patients

Exosomes, a class of extracellular vesicles of endocytic origin, play a critical role in paracrine signaling for successful cell-cell crosstalk in vivo. However, limitations in our current understanding of these circulating nanoparticles hinder efficient isolation, characterization, and downstream functional analysis of cell-specific exosomes. In this work, we sought to develop a method to isolate and characterize keratinocyte-originated exosomes (hExo κ ) from human chronic wound fluid. Furthermore, we studied the significance of hExo κ in diabetic wounds. LC-MS-MS detection of KRT14 in hExo κ and subsequent validation by Vesiclepedia and Exocarta databases identified surface KRT14 as a reliable marker of hExo κ . dSTORM nanoimaging identified KRT14+ extracellular vesicles (EV κ ) in human chronic wound fluid, 23% of which were of exosomal origin. An immunomagnetic two-step separation method using KRT14 and tetraspanin antibodies successfully isolated hExo κ from the heterogeneous pool of EV in chronic wound fluid of 15 non-diabetic and 22 diabetic patients. Isolated hExo κ (Ø75-150nm) were characterized per EV-track guidelines. dSTORM images, analyzed using online CODI followed by independent validation using Nanometrix, revealed hExo κ Ø as 80-145nm. The abundance of hExo κ was low in diabetic wound fluids and negatively correlated with patient HbA1c levels. The hExo κ isolated from diabetic wound fluid showed a low abundance of small bp RNA (<200 bp). Raman spectroscopy underscored differences in surface lipids between non-diabetic and diabetic hExo κ Uptake of hExo κ by monocyte-derived macrophages (MDM) was low for diabetics versus non-diabetics. Unlike hExo κ from non-diabetics, the addition of diabetic hExo κ to MDM polarized with LPS and INFγ resulted in sustained expression of iNOS and pro-inflammatory chemokines known to recruit macrophage (mϕ) This work provides maiden insight into the structure, composition, and function of hExo κ from chronic wound fluid thus providing a foundation for the study of exosomal malfunction under conditions of diabetic complications such as wound chronicity.

The clinical relevance of OSM in inflammatory diseases: a comprehensive review

Oncostatin M (OSM) is a pleiotropic cytokine involved in a variety of inflammatory responses such as wound healing, liver regeneration, and bone remodeling. As a member of the interleukin-6 (IL-6) family of cytokines, OSM binds the shared receptor gp130, recruits either OSMRβ or LIFRβ, and activates a variety of signaling pathways including the JAK/STAT, MAPK, JNK, and PI3K/AKT pathways. Since its discovery in 1986, OSM has been identified as a significant contributor to a multitude of inflammatory diseases, including arthritis, inflammatory bowel disease, lung and skin disease, cardiovascular disease, and most recently, COVID-19. Additionally, OSM has also been extensively studied in the context of several cancer types including breast, cervical, ovarian, testicular, colon and gastrointestinal, brain,lung, skin, as well as other cancers. While OSM has been recognized as a significant contributor for each of these diseases, and studies have shown OSM inhibition is effective at treating or reducing symptoms, very few therapeutics have succeeded into clinical trials, and none have yet been approved by the FDA for treatment. In this review, we outline the role OSM plays in a variety of inflammatory diseases, including cancer, and outline the previous and current strategies for developing an inhibitor for OSM signaling.

Damage-mediated macrophage polarization in sterile inflammation

Most of the leading causes of death, such as cardiovascular diseases, cancer, dementia, neurodegenerative diseases, and many more, are associated with sterile inflammation, either as a cause or a consequence of these conditions. The ability to control the progression of inflammation toward tissue resolution before it becomes chronic holds significant clinical potential. During sterile inflammation, the initiation of inflammation occurs through damage-associated molecular patterns (DAMPs) in the absence of pathogen-associated molecules. Macrophages, which are primarily localized in the tissue, play a pivotal role in sensing DAMPs. Furthermore, macrophages can also detect and respond to resolution-associated molecular patterns (RAMPs) and specific pro-resolving mediators (SPMs) during sterile inflammation. Macrophages, being highly adaptable cells, are particularly influenced by changes in the microenvironment. In response to the tissue environment, monocytes, pro-inflammatory macrophages, and pro-resolution macrophages can modulate their differentiation state. Ultimately, DAMP and RAMP-primed macrophages, depending on the predominant subpopulation, regulate the balance between inflammatory and resolving processes. While sterile injury and pathogen-induced reactions may have distinct effects on macrophages, most studies have focused on macrophage responses induced by pathogens. In this review, which emphasizes available human data, we illustrate how macrophages sense these mediators by examining the expression of receptors for DAMPs, RAMPs, and SPMs. We also delve into the signaling pathways induced by DAMPs, RAMPs, and SPMs, which primarily contribute to the regulation of macrophage differentiation from a pro-inflammatory to a pro-resolution phenotype. Understanding the regulatory mechanisms behind the transition between macrophage subtypes can offer insights into manipulating the transition from inflammation to resolution in sterile inflammatory diseases.

Oncostatin M: Risks and Benefits of a Novel Therapeutic Target for Atherosclerosis

BACKGROUND

Cardiovascular disease (CVD) is a leading cause of death worldwide. It is predicted that approximately 23.6 million people will die from CVDs annually by 2030. Therefore, there is a great need for an effective therapeutic approach to combat this disease. The European Cardiovascular Target Discovery (CarTarDis) consortium identified Oncostatin M (OSM) as a potential therapeutic target for atherosclerosis. The benefits of modulating OSM - an interleukin (IL)-6 family cytokine - have since been studied for multiple indications. However, as decades of high attrition rates have stressed, the success of a drug target is determined by the fine balance between benefits and the risk of adverse events. Safety issues should therefore not be overlooked.

OBJECTIVE

In this review, a risk/benefit analysis is performed on OSM inhibition in the context of atherosclerosis treatment. First, OSM signaling characteristics and its role in atherosclerosis are described. Next, an overview of in vitro, in vivo, and clinical findings relating to both the benefits and risks of modulating OSM in major organ systems is provided. Based on OSM's biological function and expression profile as well as drug intervention studies, safety concerns of inhibiting this target have been identified, assessed, and ranked for the target population.

CONCLUSION

While OSM may be of therapeutic value in atherosclerosis, drug development should also focus on de-risking the herein identified major safety concerns: tissue remodeling, angiogenesis, bleeding, anemia, and NMDA- and glutamate-induced neurotoxicity. Close monitoring and/or exclusion of patients with various comorbidities may be required for optimal therapeutic benefit.

Stromal Vascular Fraction Promotes Viability of Co-grafted Axial Skin Flaps in Rats Model

BACKGROUND

Stromal vascular fraction (SVF) has been proved in promoting the vascularization of fascial flap through cell differentiation and paracrine effect and can be autologous transplanted without culture after isolation in vitro. We intend to establish a novel co-grafted flap model of rats to investigate the efficacy and mechanism of SVF on flaps and skinsin facilitating angiogenesis and immune regulation.

METHOD

60 female Sprague Dawley rats were divided into the SVF group and the control group. A pedicled fascial flap combined with a free skin model was established, and 4×10⁶ CM-DIl labeled SVF cells were transplanted into the fascia flap; the rats were executed on days 1, 2, 3, 7, 10 postoperatively (n = 6). Flow cytometry was carried out to determine the cell proportion and surface marker of SVFs. The therapeutic effects of SVF were evaluated via Doppler blood perfusion imager, flap survival rates, histology, immunohistochemistry and immunofluorescence. The bioinformatic mechanism analysis was achieved by high-throughput RNAseq of mRNA and LncRNA.

RESULT

Flow cytometry confirmed SVF contains heterogeneous cellular composition, especially hematopoietic cells. Doppler blood perfusion imager showed SVF significantly improved flap survival with higher blood perfusion and survival rates. Immunohistochemistry of CD31 displayed higher level of angiogenesis in SVF-treated group, and CM-DIL-labeled SVF cells could survive and participate in revascularization, and RNA sequencing results revealed SVF promoted wound healing by facilitating intercellular adhesion, cell migration and positive immune response.

CONCLUSION

SVF could reduce skin flap necrosis and activated neovascularization in rats by facilitating intercellular adhesion, cell migration and regulate positive immune response.

LEVEL OF EVIDENCE N/A

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Wound fluid sampling methods for proteomic studies: A scoping review

Understanding why some wounds are hard to heal is important for improving care and developing more effective treatments. The method of sample collection used is an integral step in the research process and thus may affect the results obtained. The primary objective of this study was to summarise and map the methods currently used to sample wound fluid for protein profiling and analysis. Eligible studies were those that used a sampling method to collect wound fluid from any human wound for analysis of proteins. A search for eligible studies was performed using MEDLINE, Embase and CINAHL Plus in May 2020. All references were screened for eligibility by one reviewer, followed by discussion and consensus with a second reviewer. Quantitative data were mapped and visualised using appropriate software and summarised via a narrative summary. After screening, 280 studies were included in this review. The most commonly used group of wound fluid collection methods were vacuum, drainage or use of other external devices, with surgical wounds being the most common sample source. Other frequently used collection methods were extraction from absorbent materials, collection beneath an occlusive dressing and direct collection of wound fluid. This scoping review highlights the variety of methods used for wound fluid collection. Many studies had small sample sizes and short sample collection periods; these weaknesses have hampered the discovery and validation of novel biomarkers. Future research should aim to assess the reproducibility and feasibility of sampling and analytical methods for use in larger longitudinal studies.

Oncostatin M Improves Cutaneous Wound Re-Epithelialization and Is Deficient under Diabetic Conditions

Impaired re-epithelialization characterized by hyperkeratotic nonmigratory wound epithelium is a hallmark of nonhealing diabetic wounds. In chronic wounds, the copious release of oncostatin M (OSM) from wound macrophages is evident. OSM is a potent keratinocyte (KC) activator. This work sought to understand the signal transduction pathway responsible for wound re-epithelialization, the primary mechanism underlying wound closure. Daily topical treatment of full-thickness excisional wounds of C57BL/6 mice with recombinant murine OSM improved wound re-epithelialization and accelerated wound closure by bolstering KC proliferation and migration. OSM activated the Jak-signal transducer and activator of transcription pathway as manifested by signal transducer and activator of transcription 3 phosphorylation. Such signal transduction in the human KC induced TP63, the master regulator of KC function. Elevated TP63 induced ITGB1, a known effector of KC migration. In diabetic wounds, OSM was more abundant than the level in nondiabetic wounds. However, in diabetic wounds, OSM activity was compromised by glycation. Aminoguanidine, a deglycation agent, rescued the compromised KC migration caused by glycated OSM. Finally, topical application of recombinant OSM improved KC migration and accelerated wound closure in db/db mice. This work recognizes that despite its abundance at the wound site, OSM is inactivated by glycation, and topical delivery of exogenous OSM is likely to be productive in accelerating diabetic wound closure.

MYO-Inositol In Fermented Sugar Matrix Improves Human Macrophage Function

SCOPE

Reactive oxygen species production by innate immune cells plays a central role in host defense against invading pathogens at wound-site. A weakened hos-defense results in persistent infection leading to wound chronicity. Fermented Papaya Preparation (FPP), a complex sugar matrix, bolstered respiratory burst activity and improved wound healing outcomes in chronic wound patients. The objective of the current study was to identify underlying molecular factor/s responsible for augmenting macrophage host defense mechanisms following FPP supplementation.

METHODS AND RESULTS

In depth LC-MS/MS analysis of cells supplemented with FPP led to identification of myo-inositol as a key determinant of FPP activity towards improving macrophage function. Myo-inositol, in quantities that is present in FPP, significantly improved macrophage respiratory burst and phagocytosis via de novo synthesis pathway of ISYNA1. Additionally, myo-inositol transporters, HMIT and SMIT1, played a significant role in such activity. Blocking these pathways using siRNA attenuated FPP-induced improved macrophage host defense activities. FPP supplementation emerges as a novel approach to increase intracellular myo-inositol levels. Such supplementation also modified wound microenvironment in chronic wound patients to augment myo-inositol levels in wound fluid.

CONCLUSION

These observations indicate that myo-inositol in FPP influences multiple aspects of macrophage function critical for host defense against invading pathogens. This article is protected by copyright. All rights reserved.

RNA Profiling of Mouse Ependymal Cells after Spinal Cord Injury Identifies the Oncostatin Pathway as a Potential Key Regulator of Spinal Cord Stem Cell Fate

Ependymal cells reside in the adult spinal cord and display stem cell properties in vitro. They proliferate after spinal cord injury and produce neurons in lower vertebrates but predominantly astrocytes in mammals. The mechanisms underlying this glial-biased differentiation remain ill-defined. We addressed this issue by generating a molecular resource through RNA profiling of ependymal cells before and after injury. We found that these cells activate STAT3 and ERK/MAPK signaling post injury and downregulate cilia-associated genes and FOXJ1, a central transcription factor in ciliogenesis. Conversely, they upregulate 510 genes, seven of them more than 20-fold, namely Crym, Ecm1, Ifi202b, Nupr1, Rbp1, Thbs2 and Osmr—the receptor for oncostatin, a microglia-specific cytokine which too is strongly upregulated after injury. We studied the regulation and role of Osmr using neurospheres derived from the adult spinal cord. We found that oncostatin induced strong Osmr and p-STAT3 expression in these cells which is associated with reduction of proliferation and promotion of astrocytic versus oligodendrocytic differentiation. Microglial cells are apposed to ependymal cells in vivo and co-culture experiments showed that these cells upregulate Osmr in neurosphere cultures. Collectively, these results support the notion that microglial cells and Osmr/Oncostatin pathway may regulate the astrocytic fate of ependymal cells in spinal cord injury.

The eIF2 kinase GCN2 directs keratinocyte collective cell migration during wound healing via coordination of reactive oxygen species and amino acids

Healing of cutaneous wounds requires the collective migration of epithelial keratinocytes to seal the wound bed from the environment. However, the signaling events that coordinate this collective migration are unclear. In this report, we address the role of phosphorylation of eukaryotic initiation factor 2 (eIF2) and attendant gene expression during wound healing. Wounding of human keratinocyte monolayers in vitro led to the rapid activation of the eIF2 kinase GCN2. We determined that deletion or pharmacological inhibition of GCN2 significantly delayed collective cell migration and wound closure. Global transcriptomic, biochemical, and cellular analyses indicated that GCN2 is necessary for maintenance of intracellular free amino acids, particularly cysteine, as well as coordination of RAC1-GTP-driven reactive oxygen species (ROS) generation, lamellipodia formation, and focal adhesion dynamics following keratinocyte wounding. In vivo experiments using mice deficient for GCN2 validated the role of the eIF2 kinase during wound healing in intact skin. These results indicate that GCN2 is critical for appropriate induction of collective cell migration and plays a critical role in coordinating the re-epithelialization of cutaneous wounds.

Markers of lipid oxidation and inflammation in bronchial cells exposed to complete gasoline emissions and their organic extracts

Road traffic emissions consist of gaseous components, particles of various sizes, and chemical compounds that are bound to them. Exposure to vehicle emissions is implicated in the etiology of inflammatory respiratory disorders. We investigated the inflammation-related markers in human bronchial epithelial cells (BEAS-2B) and a 3D model of the human airways (MucilAir™), after exposure to complete emissions and extractable organic matter (EOM) from particles generated by ordinary gasoline (E5), and a gasoline-ethanol blend (E20; ethanol content 20% v/v). The production of 22 lipid oxidation products (derivatives of linoleic and arachidonic acid, AA) and 45 inflammatory molecules (cytokines, chemokines, growth factors) was assessed after days 1 and 5 of exposure, using LC-MS/MS and a multiplex immunoassay, respectively. The response observed in MucilAir™ exposed to E5 gasoline emissions, characterized by elevated levels of pro-inflammatory AA metabolites (prostaglandins) and inflammatory markers, was the most pronounced. E20 EOM exposure was associated with increased levels of AA metabolites with anti-inflammatory effects in this cell model. The exposure of BEAS-2B cells to complete emissions reduced lipid oxidation, while E20 EOM tended to increase concentrations of AA metabolite and chemokine production; the impacts on other inflammatory markers were limited. In summary, complete E5 emission exposure of MucilAir™ induces the processes associated with the pro-inflammatory response. This observation highlights the potential negative health impacts of ordinary gasoline, while the effects of alternative fuel are relatively weak.

Multiplexed Signal Ion Emission Reactive Release Amplification (SIERRA) Assay for the Culture-Free Detection of Gram-Negative and Gram-Positive Bacteria and Antimicrobial Resistance Genes

The global prevalence of antibiotic-resistant bacteria has increased the risk of dangerous infections, requiring rapid diagnosis and treatment. The standard method for diagnosis of bacterial infections remains dependent on slow culture-based methods, carried out in central laboratories, not easily extensible to rapid identification of organisms, and thus not optimal for timely treatments at the point-of-care (POC). Here, we demonstrate rapid detection of bacteria by combining electrochemical immunoassays (EC-IA) for pathogen identification with confirmatory quantitative mass spectral immunoassays (MS-IA) based on signal ion emission reactive release amplification (SIERRA) nanoparticles with unique mass labels. This diagnostic method uses compatible reagents for all involved assays and standard fluidics for automatic sample preparation at POC. EC-IA, based on alkaline phosphatase-conjugated pathogen-specific antibodies, quantified down to 104 bacteria per sample when testing Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa lysates. EC-IA quantitation was also obtained for wound samples. The MS-IA using nanoparticles against S. aureus, E. coli, Klebsiella pneumoniae, and P. aeruginosa allowed selective quantitation of ∼105 bacteria per sample. This method preserves bacterial cells allowing extraction and amplification of 16S ribosomal RNA genes and antibiotic resistance genes, as was demonstrated through identification and quantitation of two strains of E. coli, resistant and nonresistant due to β-lactamase cefotaximase genes. Finally, the combined immunoassays were compared against culture using remnant deidentified patient urine samples. The sensitivities for these immunoassays were 83, 95, and 92% for the prediction of S. aureus, P. aeruginosa, and E. coli or K. pneumoniae positive culture, respectively, while specificities were 85, 92, and 97%. The diagnostic platform presented here with fluidics and combined immunoassays allows for pathogen isolation within 5 min and identification in as little as 15 min to 1 h, to help guide the decision for additional testing, optimally only on positive samples, such as multiplexed or resistance gene assays (6 h).

Eicosanoids in Skin Wound Healing

Wound healing is an important process in the human body to protect against external threats. A dysregulation at any stage of the wound healing process may result in the development of various intractable ulcers or excessive scar formation. Numerous factors such as growth factors, cytokines, and chemokines are involved in this process and play vital roles in tissue repair. Moreover, recent studies have demonstrated that lipid mediators derived from membrane fatty acids are also involved in the process of wound healing. Among these lipid mediators, we focus on eicosanoids such as prostaglandins, thromboxane, leukotrienes, and specialized pro-resolving mediators, which are produced during wound healing processes and play versatile roles in the process. This review article highlights the roles of eicosanoids on skin wound healing, especially focusing on the biosynthetic pathways and biological functions, i.e., inflammation, proliferation, migration, angiogenesis, remodeling, and scarring.

Exosome-Mediated Crosstalk between Keratinocytes and Macrophages in Cutaneous Wound Healing

Bidirectional cell-cell communication involving exosome-borne cargo such as miRNA has emerged as a critical mechanism for wound healing. Unlike other shedding vesicles, exosomes selectively package miRNA by SUMOylation of heterogeneous nuclear ribonucleoproteinA2B1 (hnRNPA2B1). In this work, we elucidate the significance of exosome in keratinocyte-macrophage crosstalk following injury. Keratinocyte-derived exosomes were genetically labeled with GFP-reporter (Exo_κ-GFP) using tissue nanotransfection (TNT), and they were isolated from dorsal murine skin and wound-edge tissue by affinity selection using magnetic beads. Surface N-glycans of Exo_κ-GFP were also characterized. Unlike skin exosome, wound-edge Exo_κ-GFP demonstrated characteristic N-glycan ions with abundance of low-base-pair RNA and was selectively engulfed by wound macrophages (ωmϕ) in granulation tissue. In vitro addition of wound-edge Exo_κ-GFP to proinflammatory ωmϕ resulted in conversion to a proresolution phenotype. To selectively inhibit miRNA packaging within Exo_κ-GFPin vivo, pH-responsive keratinocyte-targeted siRNA-hnRNPA2B1 functionalized lipid nanoparticles (TLNP_κ) were designed with 94.3% encapsulation efficiency. Application of TLNP_{κ/si-hnRNPA2B1} to the murine dorsal wound-edge significantly inhibited expression of hnRNPA2B1 by 80% in epidermis compared to the TLNP_{κ/si-control} group. Although no significant difference in wound closure or re-epithelialization was observed, the TLNP_{κ/si-hnRNPA2B1} treated group showed a significant increase in ωmϕ displaying proinflammatory markers in the granulation tissue at day 10 post-wounding compared to the TLNP_{κ/si-control} group. Furthermore, TLNP_{κ/si-hnRNPA2B1} treated mice showed impaired barrier function with diminished expression of epithelial junctional proteins, lending credence to the notion that unresolved inflammation results in leaky skin. This work provides insight wherein Exo_κ-GFP is recognized as a major contributor that regulates macrophage trafficking and epithelial barrier properties postinjury.

Electroceutical Management of Bacterial Biofilms and Surgical Infection

Significance: In the host-microbe microenvironment, bioelectrical factors influence microbes and hosts as well as host-microbe interactions. This article discusses relevant mechanistic underpinnings of this novel paradigm. It also addresses how such knowledge may be leveraged to develop novel electroceutical solutions to manage biofilm infection. Recent Advances: Systematic review and meta-analysis of several hundred wound studies reported a 78.2% prevalence of biofilms in chronic wounds. Biofilm infection is a major cause of delayed wound healing. In the host-microbe microenvironment, bioelectrical factors influence interactions between microbes and hosts. Critical Issues: Rapid biological responses are driven by electrical signals generated by ion currents moving across cell membranes. Bacterial life, growth, and function rely on a bioelectrical milieu, which when perturbed impairs their ability to form a biofilm, a major threat to health care. Electrokinetic stability of several viral particles depend on electrostatic forces. Weak electrical field strength, otherwise safe for humans, can be anti-microbial in this context. In the host, the electric field enhanced keratinocyte migration, bolstered immune defenses, improved mitochondrial function, and demonstrated multiple other effects consistent with supporting wound healing. A deeper mechanistic understanding of bioelectrical principles will inform the design of next-generation electroceuticals. Future Directions: This is an opportune moment in time as there is a surge of interest in electroceuticals in medicine. Projected to reach $35.5 billion by 2025, electroceuticals are becoming a cynosure in the global market. The World Health Organization reports that more than 50% of surgical site infections can be antibiotic resistant. Electroceuticals offer a serious alternative.

Assessment of Acute Wound Healing using the Dorsal Subcutaneous Polyvinyl Alcohol Sponge Implantation and Excisional Tail Skin Wound Models

Wound healing is a complex process that requires the orderly progression of inflammation, granulation tissue formation, fibrosis, and resolution. Murine models provide valuable mechanistic insight into these processes; however, no single model fully addresses all aspects of the wound healing response. Instead, it is ideal to use multiple models to address the different aspects of wound healing. Here, two different methods that address diverse aspects of the wound healing response are described. In the first model, polyvinyl alcohol sponges are subcutaneously implanted along the mouse dorsum. Following sponge retrieval, cells can be isolated by mechanical disruption, and fluids can be extracted by centrifugation, thus allowing for a detailed characterization of cellular and cytokine responses in the acute wound environment. A limitation of this model is the inability to assess the rate of wound closure. For this, a tail skin excision model is utilized. In this model, a 10 mm x 3 mm rectangular piece of tail skin is excised along the dorsal surface, near the base of the tail. This model can be easily photographed for planimetric analysis to determine healing rates and can be excised for histological analysis. Both described methods can be utilized in genetically altered mouse strains, or in conjunction with models of comorbid conditions, such as diabetes, aging, or secondary infection, in order to elucidate wound healing mechanisms.

Stromal vascular fraction promotes migration of fibroblasts and angiogenesis through regulation of extracellular matrix in the skin wound healing process

BACKGROUND

A refractory wound is a typical complication of diabetes and is a common outcome after surgery. Current approaches have difficulty in improving wound healing. Recently, non-expanded stromal vascular fraction (SVF), which is derived from mature fat, has opened up new directions for the treatment of refractory wound healing. The aim of the current study is to systematically investigate the impact of SVF on wound healing, including the rate and characteristics of wound healing, ability of fibroblasts to migrate, and blood transport reconstruction, with a special emphasis on their precise molecular mechanisms.

METHODS

SVF was isolated by digestion, followed by filtration and centrifugation, and then validated by immunocytochemistry, a MTS proliferation assay and multilineage potential analysis. A wound model was generated by creating 6-mm-diameter wounds, which include a full skin defect, on the backs of streptozocin-induced hyperglycemic mice. SVF or human adipose-derived stem cell (hADSC) suspensions were subcutaneously injected, and the wounds were characterized over a 9-day period by photography and measurements. A scratch test was used to determine whether changes in the migratory ability of fibroblasts occurred after co-culture with hADSCs. Angiogenesis was observed with human umbilical vein endothelial cells. mRNA from fibroblasts, endotheliocyte, and skin tissue were sequenced by high-throughput RNAseq, and differentially expressed genes, and pathways, potentially regulated by SVF or hADSCs were bioinformatically analyzed.

RESULTS

Our data show that hADSCs have multiple characteristics of MSC. SVF and hADSCs significantly improved wound healing in hyperglycemic mice. hADSCs improve the migratory ability of fibroblasts and capillary structure formation in HUVECs. SVF promotes wound healing by focusing on angiogenesis and matrix remodeling.

CONCLUSIONS

Both SVF and hADSCs improve the function of fibroblast and endothelial cells, regulate gene expression, and promote skin healing. Various mechanisms likely are involved, including migration of fibroblasts, tubulogenesis of endothelial cells through regulation of cell adhesion, and cytokine pathways.

A Modified Collagen Dressing Induces Transition of Inflammatory to Reparative Phenotype of Wound Macrophages

Collagen containing wound-care dressings are extensively used. However, the mechanism of action of these dressings remain unclear. Earlier studies utilizing a modified collagen gel (MCG) dressing demonstrated improved vascularization of ischemic wounds and better healing outcomes. Wound macrophages are pivotal in facilitating wound angiogenesis and timely healing. The current study was designed to investigate the effect of MCG on wound macrophage phenotype and function. MCG augmented recruitment of macrophage at the wound-site, attenuated pro-inflammatory and promoted anti-inflammatory macrophage polarization. Additionally, MCG increased anti-inflammatory IL-10, IL-4 and pro-angiogenic VEGF production, indicating a direct role of MCG in resolving wound inflammation and improving angiogenesis. At the wound-site, impairment in clearance of apoptotic cell bioburden enables chronic inflammation. Engulfment of apoptotic cells by macrophages (efferocytosis) resolves inflammation via a miR-21-PDCD4-IL-10 pathway. MCG-treated wound macrophages exhibited a significantly bolstered efferocytosis index. Such favorable outcome significantly induced miR-21 expression. MCG-mediated IL-10 production was dampened under conditions of miR-21 knockdown pointing towards miR-21 as a causative factor. Pharmacological inhibition of JNK attenuated IL-10 production by MCG, implicating miR-21-JNK pathway in MCG-mediated IL-10 production by macrophages. This work provides direct evidence demonstrating that a collagen-based wound-care dressing may influence wound macrophage function and therefore modify wound inflammation outcomes.

Skin Transcriptome of Middle-Aged Women Supplemented With Natural Herbo-mineral Shilajit Shows Induction of Microvascular and Extracellular Matrix Mechanisms

Objective: Shilajit is a pale-brown to blackish-brown organic mineral substance available from Himalayan rocks. We demonstrated that in type I obese humans, shilajit supplementation significantly upregulated extracellular matrix (ECM)-related genes in the skeletal muscle. Such an effect was highly synergistic with exercise. The present study (clinicaltrials.gov NCT02762032) aimed to evaluate the effects of shilajit supplementation on skin gene expression profile and microperfusion in healthy adult females. Methods: The study design comprised six total study visits including a baseline visit (V1) and a final 14-week visit (V6) following oral shilajit supplementation (125 or 250 mg bid). A skin biopsy of the left inner upper arm of each subject was collected at visit 2 and visit 6 for gene expression profiling using Affymetrix Clariom™ D Assay. Skin perfusion was determined by MATLAB processing of dermascopic images. Transcriptome data were normalized and subjected to statistical analysis. The differentially regulated genes were subjected to Ingenuity Pathway Analysis (IPA®). The expression of the differentially regulated genes identified by IPA® were verified using real-time polymerase chain reaction (RT-PCR). Results: Supplementation with shilajit for 14 weeks was not associated with any reported adverse effect within this period. At a higher dose (250 mg bid), shilajit improved skin perfusion when compared to baseline or the placebo. Pathway analysis identified shilajit-inducible genes relevant to endothelial cell migration, growth of blood vessels, and ECM which were validated by quantitative real-time polymerase chain reaction (RT-PCR) analysis. Conclusions: This work provides maiden evidence demonstrating that oral shilajit supplementation in adult healthy women induced genes relevant to endothelial cell migration and growth of blood vessels. Shilajit supplementation improved skin microperfusion.

Biobehavioral Mechanisms Associated With Nonhealing Wounds and Psychoneurologic Symptoms (Pain, Cognitive Dysfunction, Fatigue, Depression, and Anxiety) in Older Individuals With Chronic Venous Leg Ulcers

The prevalence and incidence of chronic venous leg ulcers (CVLUs) are increasing worldwide, as are the associated financial costs. Although it has long been known that their underlying etiology is venous insufficiency, the molecular aspects of healing versus nonhealing, as well as the psychoneurologic symptoms (PNS; pain, cognitive dysfunction, fatigue, depression, and anxiety) associated with CVLUs remain understudied. In this biobehaviorally focused review, we aim to elucidate the complex mechanisms that link the biological and molecular aspects of CLVUs with their PNS. Innovations in "omics" research have increased our understanding of important wound microenvironmental factors (e.g., inflammation, microbial pathogenic biofilm, epigenetic processes) that may adversely alter the wound bed's molecular milieu so that microbes evade immune detection. Although these molecular factors are not singularly responsible for wound healing, they are major components of wound development, nonhealing, and PNS that, until now, have not been amenable to systematic study, especially over time. Further, this review explores our current understanding of the molecular mechanisms by which the immune activation that contributes to the development and persistence of CVLUs also leads to the development, persistence, and severity of wound-related PNS. We also make recommendations for future research that will expand the field of biobehavioral wound science. Biobehavioral research that focuses on the interrelated mechanisms of PNS will lead to symptom-management interventions that improve quality of life for the population burdened by CVLUs.

Loss of the TAM Receptor Axl Ameliorates Severe Zika Virus Pathogenesis and Reduces Apoptosis in Microglia

The TAM receptor, Axl, has been implicated as a candidate entry receptor for Zika virus (ZIKV) infection but has been shown as inessential for virus infection in mice. To probe the role of Axl in murine ZIKV infection, we developed a mouse model lacking the Axl receptor and the interferon alpha/beta receptor (Ifnar^−/−Axl^−/−), conferring susceptibility to ZIKV. This model validated that Axl is not required for murine ZIKV infection and that mice lacking Axl are resistant to ZIKV pathogenesis. This resistance correlates to lower pro-interleukin-1β production and less apoptosis in microglia of ZIKV-infected mice. This apoptosis occurs through both intrinsic (caspase 9) and extrinsic (caspase 8) manners, and is age dependent, as younger Axl-deficient mice are susceptible to ZIKV pathogenesis. These findings suggest that Axl plays an important role in pathogenesis in the brain during ZIKV infection and indicates a potential role for Axl inhibitors as therapeutics during viral infection.

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IFNAR^−/−Axl^−/− mice show Axl unnecessary for Zika virus replication in mice

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Mice lacking Axl receptor are significantly resistant to Zika virus neuropathogenesis

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IFNAR^−/−Axl^−/− mice have less ZIKV-driven caspase-dependent apoptosis in brain

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Axl deficient mice have fewer apoptotic microglia after ZIKV infection

Eicosanoids in tissue repair

Trauma or infection can result in tissue damage, which needs to be repaired in a well-orchestrated manner to restore tissue function and homeostasis. Lipid mediators derived from arachidonic acid (termed eicosanoids) play central and versatile roles in the regulation of tissue repair. Here, I summarize the current state-of the-art regarding the functional activities of eicosanoids in tissue repair responses during homeostasis and disease. I also describe how eicosanoids are produced during tissue damage and repair in a time-, cell- and tissue-dependent fashion. In particular, recent insights into the roles of eicosanoids in epithelial barrier repair are reviewed. Furthermore, the distinct roles of different eicosanoids in settings of pathological tissue repair such as chronic wounds, scarring or fibrosis are discussed. Finally, an outlook is provided on how eicosanoids may be targeted by future therapeutic strategies to achieve physiological tissue repair and prevent scarring and loss of tissue function in various disease contexts.

Altered metabolic pathways regulate synovial inflammation in rheumatoid arthritis

Rheumatoid arthritis is characterized by synovial proliferation, neovascularization and leucocyte extravasation leading to joint destruction and functional disability. The blood vessels in the inflamed synovium are highly dysregulated, resulting in poor delivery of oxygen; this, along with the increased metabolic demand of infiltrating immune cells and inflamed resident cells, results in the lack of key nutrients at the site of inflammation. In these adverse conditions synovial cells must adapt to generate sufficient energy to support their proliferation and activation status, and thus switch their cell metabolism from a resting regulatory state to a highly metabolically active state. This alters redox-sensitive signalling pathways and also results in the accumulation of metabolic intermediates which, in turn, can act as signalling molecules that further exacerbate the inflammatory response. The RA synovium is a multi-cellular tissue, and while many cell types interact to promote the inflammatory response, their metabolic requirements differ. Thus, understanding the complex interplay between hypoxia-induced signalling pathways, metabolic pathways and the inflammatory response will provide better insight into the underlying mechanisms of disease pathogenesis.

Inflammatory response and biomechanical properties of coaxial scaffolds for engineered skin in vitro and post-grafting

Engineered skin (ES) offers many advantages over split-thickness skin autografts for the treatment of burn wounds. However, ES, both in vitro and after grafting, is often significantly weaker, less elastic and more compliant than normal human skin. Biomechanical properties of ES can be tuned in vitro using electrospun co-axial (CoA) scaffolds. To explore the potential for coaxial scaffold-based ES use in vivo, two CoA scaffolds were fabricated with bioactive gelatin shells and biodegradable synthetic cores of polylactic acid (PLA) and polycaprolactone (PCL), and compared with gelatin monofilament scaffolds. Fibroblast and macrophage production of inflammatory cytokines interleukin 6 (IL-6) and transforming growth factor β-1 was significantly higher when cultured on PLA and PCL monofilament scaffolds compared to gelatin monofilament scaffolds. The core-shell fiber configuration significantly reduced production of pro-inflammatory cytokines to levels similar to those of gelatin monofilament scaffolds. In vitro, ES mechanical properties were significantly enhanced using CoA scaffolds; however, after grafting CoA- and gelatin-based ES to full-thickness excisional wounds on athymic mice, the in vitro mechanical advantage of CoA grafts was lost. A substantially increased inflammatory response to CoA-based ES was observed, with upregulation of IL-6 expression and a significant M2 macrophage presence. Additionally, expression of matrix metalloproteinase I was upregulated and collagen type I alpha 1 was downregulated in CoA ES two weeks after grafting. These results suggest that while coaxial scaffolds provide the ability to regulate biomechanics in vitro, further investigation of the inflammatory response to core materials is required to optimize this strategy for clinical use. STATEMENT OF SIGNIFICANCE: Engineered skin has been used to treat very large burn injuries. Despite its ability to heal these wounds, engineered skin exhibits reduced biomechanical properties making it challenging to manufacture and surgically apply. Coaxial fiber scaffolds have been utilized to tune the mechanical properties of engineered skin while maintaining optimal biological properties but it is not known how these perform on a patient especially with regards to their inflammatory response. The current study examines the biomechanical and inflammatory properties of coaxial scaffolds and uniaxial scaffolds in vitro and in vivo. The results show that the biological response to the scaffold materials is a critical determinant of tissue properties after grafting with reduced inflammation and rapid scaffold remodeling leading to stronger skin.

Nonsteroidal Anti-inflammatory Drugs Potently Inhibit the Replication of Zika Viruses by Inducing the Degradation of AXL

Zika virus (ZIKV) is genetically and biologically related to other Flaviviridae family members and has disseminated to many countries. It is associated with severe consequences, including the abnormal development of the neural system in fetuses and neurological diseases in adults. Therefore, the development of anti-ZIKV drugs is of paramount importance. Screening of generic drugs revealed that several nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, ibuprofen, naproxen, acetaminophen, and lornoxicam, potently inhibited the entry of Zika virus Env/HIV-1-pseudotyped viruses. They also significantly inhibited the replication of wild-type ZIKV both in cell lines and in primary human fetal endothelial cells. Interestingly, the NSAIDs exerted this inhibitory effect by potently reducing the expression of AXL, the entry cofactor of ZIKV. Further studies showed that the NSAIDs downregulated the prostaglandin E₂/prostaglandin E receptor 2 (EP2)/cAMP/protein kinase A (PKA) signaling pathway and reduced PKA-dependent CDC37 phosphorylation and the interaction between CDC37 and HSP90, which subsequently facilitated CHIP/ubiquitination/proteasome-mediated AXL degradation. Taken together, our results highlight a new mechanism of action of antiviral agents which may assist in designing a convenient strategy for treating ZIKV-infected patients.IMPORTANCE Zika virus (ZIKV) infection, which causes congenital malformations, including microcephaly and other neurological disorders, has attracted global attention. We observed that several NSAIDs significantly inhibited ZIKV infection. Based on our observations, we propose a novel mechanism of action of antiviral compounds which involves the blockade of virus entry via degradation of the entry cofactor. Furthermore, NSAIDs can be practically used for preventing ZIKV infection in pregnant women, as certain NSAIDs, including ibuprofen and acetaminophen, are considered clinically safe.

Pharmacologic targeting of the diabetic stem cell mobilopathy

Diabetes is a chronic metabolic disease characterized by hyperglycemia and several associated biochemical abnormalities. Diabetes leads to multiorgan complications that collectively reduce life expectancy. Hematopoietic stem cells (HSCs) are nested within bone marrow (BM) niches whence they can be mobilized to the peripheral circulation. Clinically, this is done for HSC collection and autologous or allogenic transplantation. A great amount of data from basic and clinical studies support that diabetic patients are poor HSC mobilizers owing to BM remodeling. Dysfunction of the BM shares pathophysiological features and pathways with typical chronic diabetic complications that affect other issues (e.g. the retina and the kidney). From a clinical perspective, impaired HSC mobilization translates into the failure to collect a minimum number of CD34⁺ cells to achieve a safe engraftment after transplantation. Furthermore, blunted mobilization is associated with reduced steady-state levels of circulating HSCs, which have been consistently described in diabetic patients and associated with increased risk of adverse outcomes, including cardiovascular events and death. In this review, we discuss the most clinically relevant pharmacological options to overcome impaired HSC mobilization in diabetes. These therapeutic strategies may result in an improved outcome of diabetic patients undergoing HSC transplantation and restore circulating HSC levels, thereby protecting from adverse cardiovascular outcomes.

Topical Lyophilized Targeted Lipid Nanoparticles in the Restoration of Skin Barrier Function following Burn Wound

Lyophilized keratinocyte-targeted nanocarriers (TLN_κ) loaded with locked nucleic acid (LNA) modified anti-miR were developed for topical application to full thickness burn injury. TLN_κ were designed to selectively deliver LNA-anti-miR-107 to keratinocytes using the peptide sequence ASKAIQVFLLAG. TLN_κ employed DOTAP/DODAP combination pH-responsive lipid components to improve endosomal escape. To minimize interference of clearance by non-targeted cells, especially immune cells in the acute wound microenvironment, surface charge was neutralized. Lyophilization was performed to extend the shelf life of the lipid nanoparticles (LNPs). Encapsulation efficiency of anti-miR in lyophilized TLN_κ was estimated to be 96.54%. Cargo stability of lyophilized TLN_κ was tested. After 9 days of loading with anti-miR-210, TLN_κ was effective in lowering abundance of the hypoxamiR miR-210 in keratinocytes challenged with hypoxia. Keratinocyte uptake of DiD-labeled TLN_κ was selective and exceeded 90% within 4 hr. Topical application of hydrogel-dispersed lyophilized TLN_κ encapsulating LNA anti-miR-107 twice a week significantly accelerated wound closure and restoration of skin barrier function. TLN_{κ/anti-miR-107} application depleted miR-107 and upregulated dicer expression, which accelerated differentiation of keratinocytes. Expression of junctional proteins such as claudin-1, loricrin, filaggrin, ZO-1, and ZO-2 were significantly upregulated following TLN_{κ/anti-miR-107} treatment. These LNPs are promising as topical therapeutic agents in the management of burn injury.

Fifty-Patient Study Evaluating the Efficacy of Modified Collagen With Glycerin in Periwound Skin Management

The management of chronic nonhealing ulcers pose a great challenge because they are associated with morbidity and increased costs. This report presents the observations of standard management along with application of modified collagen with glycerin (MCG) in the periwound area for management of nonhealing wounds. This observational report included 50 patients (33 male, 17 female) aged 24 to 94 years having nonhealing wounds. All wounds were treated using standard treatment protocols (TIME concept), whereas the periwound severity was assessed using the Harikrishna Periwound Skin Classification (HPSC). All patients received once-daily application of MCG lotion directly in the periwound areas and compression bandaging until there was complete wound healing. Patient compliance was ensured by regular follow-up and counseling. All diabetic patients were counseled to ensure glycemic control during the entire follow-up period. The criteria used for wound healing were based on clinical observation, and proper epithelialization of the wound was the end point. The median age of the wounds was 12.0 weeks (95% CI = 8.00 – 58.08). Majority of the non-healing wounds were diabetic foot ulcers with age of wound between 4 weeks to 15 years. The median time to complete wound healing was 12.71 (95% CI = 10.00-16.67) weeks. Standard treatment protocol of TIME principle with periwound area assessment based on HPSC 2015 and treatment accordingly with topical application of MCG along with additional measures has shown complete healing of nonhealing wounds. However, further large-scale comparative studies are needed to substantiate these effects on a larger population.

Mechanism of prostaglandin E2-induced transcriptional up-regulation of Oncostatin-M by CREB and Sp1

Oncostatin-M (OSM) is a pleotropic cytokine belonging to the interleukin-6 family. Differential expression of OSM in response to varying stimuli and exhibiting repertoire of functions in different cells renders it challenging to study the mechanism of its expression. Prostaglandin E₂ (PGE₂) transcriptionally increased osm levels. In silico studies of ∼1 kb upstream of osm promoter region yielded the presence of CRE (cyclic AMP response element)-like sites at the distal end (CRE_osm). Deletion and point mutation of CRE_osm clearly indicated that this region imparted an important role in PGE₂-mediated transcription. Nuclear protein(s) from PGE₂-treated U937 cells, bound to this region, was identified as CRE-binding protein (CREB). CREB was phosphorylated on treatment and was found to be directly associated with CRE_osm The presence of cofactors p300 and CREB-binding protein in the complex was confirmed. A marked decrease in CREB phosphorylation, binding and transcriptional inhibition on treatment with PKA (protein kinase A) inhibitor, H89 (N-[2-[[3-(4-bromophenyl)-2-propenyl]amino]ethyl]-5-soquinolinesulfonamide), revealed the role of phosphorylated CREB in osm transcription. Additionally, other nuclear protein(s) were specifically associated with the proximal GC region (GC_osm) post PGE₂ treatment, later confirmed to be specificity protein 1 (Sp1). Interestingly, Sp1 bound to the proximal osm promoter was found to be associated with phospho-CREB-p300 complex bound to the distal osm promoter. Knockdown of Sp1 abrogated the expression and functionality of OSM. Thus, the present study conclusively proves that these transcription factors, bound at the distal and proximal promoter elements are found to associate with each other in a DNA-dependent manner and both are responsible for the PGE₂-mediated transcriptional up-regulation of Oncostatin-M.

Novel mechanisms of Collagenase Santyl Ointment (CSO) in wound macrophage polarization and resolution of wound inflammation

Collagenases are useful in enzymatic wound debridement. Clostridial collagenase, marketed as Collagenase Santyl Ointment (CSO), is FDA approved for such use. Building on the scientific premise that collagenases as well as collagen degradation products may regulate immune cell function, we sought to investigate the potential role of CSO in wound inflammation. We tested the hypothesis that in addition to enacting debridement, CSO contributes to the resolution of persistent wound inflammation. Wound macrophages were isolated from PVA sponges loaded with CSO or petrolatum and implanted in mice. Significant increase in pro-reparative and decrease in pro-inflammatory polarization was noted in macrophages of acute as well as diabetic wounds. Wound macrophages from CSO-treated group displayed increased production of anti-inflammatory cytokines IL-10 and TGF-β, and decreased levels of pro-inflammatory cytokines TNF-α and IL-1β. The active ingredient of CSO, CS-API, induced the expression of mϕ^heal /M(IL-4) polarization markers ex vivo. CS-API treatment attenuated transactivation of NF-κB and significantly induced STAT6 phosphorylation. A significant role of a novel PGE2-EP4 pathway in CS-API induced STAT6 activation and the mϕ^heal /M(IL-4) polarization was identified. Taken together, findings of this work reposition CSO as a potential agent that may be effective in resolving wound inflammation, including diabetic wounds.

Plaque Calcification During Atherosclerosis Progression and Regression

Plaque calcification develops by the inflammation-dependent mechanisms involved in progression and regression of atherosclerosis. Macrophages can undergo two distinct polarization states, that is, pro-inflammatory M1 phenotype in progression and anti-inflammatory M2 phenotype in regression. In plaque progression, predominant M1 macrophages promote the initial calcium deposition within the necrotic core of the lesions, called as microcalcification, through not only vesicle-mediated mineralization as the result of apoptosis of macrophages and vascular smooth muscle cells (VSMCs), but also VSMC differentiation into early phase osteoblasts. On the other hand, in plaque regression M2 macrophages are engaged in the healing response to plaque inflammation. In association with the resolution of chronic inflammation, M2 macrophages may facilitate macroscopic calcium deposition, called as macrocalcification, through induction of osteoblastic differentiation and maturation of VSMCs. Oncostatin M, which has been shown to promote osteoblast differentiation in bone, may play a pivotal role in the development of plaque calcification. Clinically, two types of plaque calcification have distinct implications. Macrocalcification leads to plaque stability, while microcalcification is more likely to be associated with plaque rupture. Statin therapy, which reduces cardiovascular mortality, has been shown to exert its dual actions on plaque morphology, that is, regression of atheroma and increment of macroscopic calcium deposits. Statins may facilitate the healing process against plaque inflammation by enhancing M2 polarization of macrophages. Vascular calcification has pleiotropic properties as pro-inflammatory “microcalcification” and anti-inflammatory “macrocalcification”. The molecular mechanisms of this process in relation with plaque progression as well as plaque regression should be intensively elucidated.

Coupling between Myogenesis and Angiogenesis during Skeletal Muscle Regeneration Is Stimulated by Restorative Macrophages

In skeletal muscle, new functions for vessels have recently emerged beyond oxygen and nutrient supply, through the interactions that vascular cells establish with muscle stem cells. Here, we demonstrate in human and mouse that endothelial cells (ECs) and myogenic progenitor cells (MPCs) interacted together to couple myogenesis and angiogenesis in vitro and in vivo during skeletal muscle regeneration. Kinetics of gene expression of ECs and MPCs sorted at different time points of regeneration identified three effectors secreted by both ECs and MPCs. Apelin, Oncostatin M, and Periostin were shown to control myogenesis/angiogenesis coupling in vitro and to be required for myogenesis and vessel formation during muscle regeneration in vivo. Furthermore, restorative macrophages, which have been previously shown to support myogenesis in vivo, were shown in a 3D triculture model to stimulate myogenesis/angiogenesis coupling, notably through Oncostatin M production. Our data demonstrate that restorative macrophages orchestrate muscle regeneration by controlling myogenesis/angiogenesis coupling.

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Endothelial cells (ECs) promote myogenesis

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Myogenic progenitor cells (MPCs) stimulate angiogenesis as they differentiate

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EC- and MPC-derived Apelin, Oncostatin M, and Periostin promote myo-angiogenesis

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Restorative macrophages stimulate myo-angiogenesis via Oncostatin M secretion

Diabetes mellitus as a poor mobilizer condition

Hematopoietic stem cell (HSC) transplantation in an effective and curative therapy for numerous hematological malignancies. Mobilization of HSCs from bone marrow (BM) to peripheral blood (PB) followed by apheresis is the gold standard for obtaining HSCs for both autologous and allogeneic stem cell transplantation. After administration of granulocyte-colony stimulating factor (G-CSF), up to 30% of patients fail to mobilize "optimal" numbers of HSCs required for engraftment. This review summarizes the current experimental and clinical evidence that diabetes mellitus is a risk factor for poor mobilization. Diabetes causes a profound remodeling of the HSC niche, resulting in impaired release of HSCs. Experimental studies indicate that hyperglycemia hampers regulation of CXCL12 and clinical studies suggest that diabetes impairs HSC mobilization especially in response to G-CSF, but less to plerixafor. Understanding further the biochemical alterations in the diabetic BM will provide insights into future therapeutic strategies to reverse the so-called "diabetic stem cell mobilopathy".

The barrier hypothesis and Oncostatin M: Restoration of epithelial barrier function as a novel therapeutic strategy for the treatment of type 2 inflammatory disease

Mucosal epithelium maintains tissue homeostasis through many processes, including epithelial barrier function, which separates the environment from the tissue. The barrier hypothesis of type 2 inflammatory disease postulates that epithelial and epidermal barrier dysfunction, which cause inappropriate exposure to the environment, can result in allergic sensitization and development of type 2 inflammatory disease. The restoration of barrier dysfunction once it's lost, or the prevention of barrier dysfunction, have the potential to be exciting new therapeutic strategies for the treatment of type 2 inflammatory disease. Neutrophil-derived Oncostatin M has been shown to be a potent disrupter of epithelial barrier function through the induction of epithelial-mesenchymal transition (EMT). This review will discuss these events and outline several points along this axis at which therapeutic intervention could be beneficial for the treatment of type 2 inflammatory diseases.

Molecular Aspects of Wound Healing and the Rise of Venous Leg Ulceration: Omics Approaches to Enhance Knowledge and Aid Diagnostic Discovery

Chronic wounds, in particular venous leg ulcers (VLU), represent a substantial burden for economies, healthcare systems and societies worldwide. This burden is exacerbated by the recalcitrant nature of these wounds, despite best practice, evidence-based care, which substantially reduces the quality of life of patients. Furthermore, co-morbidities such as diabetes and cardiovascular disease within ageing populations further contribute to the increasing prevalence in developed countries. This review provides an overview of the literature concerning the cellular and molecular mechanisms of wound healing and aspects where this process fails, resulting in a chronic wound. VLU may arise from chronic venous disease, which presents with many clinical manifestations and can lead to a highly complex disease state. Efforts to comprehend this state using various omics based approaches have delivered some insight into the underlying biology of chronic wounds and revealed markers of differentiation at the genomic, transcriptomic, proteomic and metabolomic levels. Furthermore, this review outlines the array of analytical tools and approaches that have been utilised for capturing multivariate data at each of these molecular levels. Future developments in spatiotemporal analysis of wounds along with the integration of multiple omics datasets may provide much needed information on the key molecules that drive wound chronicity. Such biomarkers have the potential to be developed into clinically relevant diagnostic tools to aid in personalised wound management.

Correction of MFG-E8 Resolves Inflammation and Promotes Cutaneous Wound Healing in Diabetes

Milk fat globule epidermal growth factor-factor 8 (MFG-E8) is a peripheral glycoprotein that acts as a bridging molecule between the macrophage and apoptotic cells, thus executing a pivotal role in the scavenging of apoptotic cells from affected tissue. We have previously reported that apoptotic cell clearance activity or efferocytosis is compromised in diabetic wound macrophages. In this work, we test the hypothesis that MFG-E8 helps resolve inflammation, supports angiogenesis, and accelerates wound closure. MFG-E8(-/-) mice displayed impaired efferocytosis associated with exaggerated inflammatory response, poor angiogenesis, and wound closure. Wound macrophage-derived MFG-E8 was recognized as a critical driver of wound angiogenesis. Transplantation of MFG-E8(-/-) bone marrow to MFG-E8(+/+) mice resulted in impaired wound closure and compromised wound vascularization. In contrast, MFG-E8(-/-) mice that received wild-type bone marrow showed improved wound closure and improved wound vascularization. Hyperglycemia and exposure to advanced glycated end products inactivated MFG-E8, recognizing a key mechanism that complicates diabetic wound healing. Diabetic db/db mice suffered from impaired efferocytosis accompanied with persistent inflammation and slow wound closure. Topical recombinant MFG-E8 induced resolution of wound inflammation, improvements in angiogenesis, and acceleration of closure, upholding the potential of MFG-E8-directed therapeutics in diabetic wound care.

A compendium of monocyte transcriptome datasets to foster biomedical knowledge discovery

Systems-scale profiling approaches have become widely used in translational research settings. The resulting accumulation of large-scale datasets in public repositories represents a critical opportunity to promote insight and foster knowledge discovery. However, resources that can serve as an interface between biomedical researchers and such vast and heterogeneous dataset collections are needed in order to fulfill this potential. Recently, we have developed an interactive data browsing and visualization web application, the Gene Expression Browser (GXB). This tool can be used to overlay deep molecular phenotyping data with rich contextual information about analytes, samples and studies along with ancillary clinical or immunological profiling data. In this note, we describe a curated compendium of 93 public datasets generated in the context of human monocyte immunological studies, representing a total of 4,516 transcriptome profiles. Datasets were uploaded to an instance of GXB along with study description and sample annotations. Study samples were arranged in different groups. Ranked gene lists were generated based on relevant group comparisons. This resource is publicly available online at http://monocyte.gxbsidra.org/dm3/landing.gsp.

Expanding horizons of cellular plasticity in regenerative medicine

This Guest Editorial introduces the Regenerative Medicine Theme Issue, which provides critical insight into the unfolding frontier of regenerative medicine.

A curated compendium of monocyte transcriptome datasets of relevance to human monocyte immunobiology research

Systems-scale profiling approaches have become widely used in translational research settings. The resulting accumulation of large-scale datasets in public repositories represents a critical opportunity to promote insight and foster knowledge discovery. However, resources that can serve as an interface between biomedical researchers and such vast and heterogeneous dataset collections are needed in order to fulfill this potential. Recently, we have developed an interactive data browsing and visualization web application, the Gene Expression Browser (GXB). This tool can be used to overlay deep molecular phenotyping data with rich contextual information about analytes, samples and studies along with ancillary clinical or immunological profiling data. In this note, we describe a curated compendium of 93 public datasets generated in the context of human monocyte immunological studies, representing a total of 4,516 transcriptome profiles. Datasets were uploaded to an instance of GXB along with study description and sample annotations. Study samples were arranged in different groups. Ranked gene lists were generated based on relevant group comparisons. This resource is publicly available online at http://monocyte.gxbsidra.org/dm3/landing.gsp.

Oncostatin M Promotes Osteoblastic Differentiation of Human Vascular Smooth Muscle Cells Through JAK3-STAT3 Pathway

Vascular calcification is a clinically significant component of atherosclerosis and arises from chronic vascular inflammation. Oncostatin M (OSM) derived from plaque macrophages may contribute to the development of atherosclerotic calcification. Here, we investigated the stimulatory effects of OSM on osteoblastic differentiation of human vascular smooth muscle cells (HVSMC) derived from various arteries including umbilical artery, aorta, and coronary artery and its signaling pathway. Osteoblastic differentiation was induced by exposure of HVSMC to osteogenic differentiation medium (ODM) (10% fetal bovine serum, 0.1 μM dexamethasone, 10 mM β-glycerophosphate and 50 μg/ml ascorbic acid 2-phosphate in Dulbecco's modified Eagle's medium [DMEM]). OSM significantly increased alkaline phosphate (ALP) activity and matrix mineralization in HVSMC from all sources. Osteoblast marker genes such as ALP and Runx2 were also up-regulated by OSM in these cells. OSM treatment induced activation of STAT3 in HVSMC from umbilical artery as evidenced by immunoblot. Moreover, not only a JAK3 inhibitor, WHI-P154, but also knockdown of JAK3 by siRNA prevented the OSM-induced ALP activity and matrix mineralization in umbilical artery HVSMC. On the other hand, silencing of STAT3 almost completely suppressed OSM-induced ALP expression and matrix mineralization in HVSMC from all sources. These data suggest that OSM promotes osteoblastic differentiation of vascular smooth muscle cells through JAK3/STAT3 pathway and may contribute to the development of atherosclerotic calcification.

Monocyte and macrophage plasticity in tissue repair and regeneration

Heterogeneity and high versatility are the characteristic features of the cells of monocyte-macrophage lineage. The mononuclear phagocyte system, derived from the bone marrow progenitor cells, is primarily composed of monocytes, macrophages, and dendritic cells. In regenerative tissues, a central role of monocyte-derived macrophages and paracrine factors secreted by these cells is indisputable. Macrophages are highly plastic cells. On the basis of environmental cues and molecular mediators, these cells differentiate to proinflammatory type I macrophage (M1) or anti-inflammatory or proreparative type II macrophage (M2) phenotypes and transdifferentiate into other cell types. Given a central role in tissue repair and regeneration, the review focuses on the heterogeneity of monocytes and macrophages with current known mechanisms of differentiation and plasticity, including microenvironmental cues and molecular mediators, such as noncoding RNAs.

Cancer and the microbiome: potential applications as new tumor biomarker

Microbial communities that colonize in humans are collectively described as microbiome. According to conservative estimates, about 15% of all types of neoplasms are related to different infective agents. However, current knowledge is not sufficient to explain how the microbiome contributes to the growth and development of cancers. Large and thorough studies involving colonized, diverse and complex microbiome entities are required to identify microbiome as a potential cancer marker and to understand how the immune system is involved in response to pathogens. This article reviews the existing evidence supporting the enigmatic association of transformed microbiome with the development of cancer through the immunological modification. Ascertaining the connection between microbiome and immunological responses with risk of cancer may direct to explaining significant advances in the etiology of cancer, potentially disclosing a novel paradigm of research for the management and prevention of cancer.

A modified collagen gel dressing promotes angiogenesis in a preclinical swine model of chronic ischemic wounds

We recently performed proteomic characterization of a modified collagen gel (MCG) dressing and reported promising effects of the gel in healing full-thickness excisional wounds. In this work, we test the translational relevance of our aforesaid findings by testing the dressing in a swine model of chronic ischemic wounds recently reported by our laboratory. Full-thickness excisional wounds were established in the center of bipedicle ischemic skin flaps on the backs of animals. Ischemia was verified by laser Doppler imaging, and MCG was applied to the test group of wounds. Seven days post wounding, macrophage recruitment to the wound was significantly higher in MCG-treated ischemic wounds. In vitro, MCG up-regulated expression of Mrc-1 (a reparative M2 macrophage marker) and induced the expression of anti-inflammatory cytokine interleukin (IL)-10 and of fibroblast growth factor-basic (β-FGF). An increased expression of CCR2, an M2 macrophage marker, was noted in the macrophages from MCG treated wounds. Furthermore, analyses of wound tissues 7 days post wounding showed up-regulation of transforming growth factor-β, vascular endothelial growth factor, von Willebrand's factor, and collagen type I expression in MCG-treated ischemic wounds. At 21 days post wounding, MCG-treated ischemic wounds displayed higher abundance of proliferating endothelial cells that formed mature vascular structures and increased blood flow to the wound. Fibroblast count was markedly higher in MCG-treated ischemic wound-edge tissue. In addition, MCG-treated wound-edge tissues displayed higher abundance of mature collagen with increased collagen type I : III deposition. Taken together, MCG helped mount a more robust inflammatory response that resolved in a timely manner, followed by an enhanced proliferative phase, angiogenic outcome, and postwound tissue remodeling. Findings of the current study warrant clinical testing of MCG in a setting of ischemic chronic wounds.

Temporal gene profiling of the 5XFAD transgenic mouse model highlights the importance of microglial activation in Alzheimer's disease

BACKGROUND

The 5XFAD early onset mouse model of Alzheimer's disease (AD) is gaining momentum. Behavioral, electrophysiological and anatomical studies have identified age-dependent alterations that can be reminiscent of human AD. However, transcriptional changes during disease progression have not yet been investigated. To this end, we carried out a transcriptomic analysis on RNAs from the neocortex and the hippocampus of 5XFAD female mice at the ages of one, four, six and nine months (M1, M4, M6, M9).

RESULTS

Our results show a clear shift in gene expression patterns between M1 and M4. At M1, 5XFAD animals exhibit region-specific variations in gene expression patterns whereas M4 to M9 mice share a larger proportion of differentially expressed genes (DEGs) that are common to both regions. Analysis of DEGs from M4 to M9 underlines the predominance of inflammatory and immune processes in this AD mouse model. The rise in inflammation, sustained by the overexpression of genes from the complement and integrin families, is accompanied by an increased expression of transcripts involved in the NADPH oxidase complex, phagocytic processes and IFN-γ related pathways.

CONCLUSIONS

Overall, our data suggest that, from M4 to M9, sustained microglial activation becomes the predominant feature and point out that both detrimental and neuroprotective mechanisms appear to be at play in this model. Furthermore, our study identifies a number of genes already known to be altered in human AD, thus confirming the use of the 5XFAD strain as a valid model for understanding AD pathogenesis and for screening potential therapeutic molecules.

Tyro3, Axl, and Mertk receptor signaling in inflammatory bowel disease and colitis-associated cancer

Three receptor tyrosine kinases, Tyro3, Axl, and Mertk (TAM) and their ligands Gas6 and Protein S, have emerged as potent negative regulators of innate immune responses. A number of studies using genetic ablation of TAM loci in mice have elucidated the mechanism of TAM engagement and function during the immune response and removal of apoptotic cells. Following phagocytosis of apoptotic cells or the induction of T-cell dependent adaptive immune responses, ligand-induced TAM signaling dampens proinflammatory cytokine production and thus prevents exaggerated or prolonged inflammation. It is believed that the TAM pathway may play an important role in the pathogenesis of inflammatory bowel disease. Suppression of inflammation and removal of apoptotic cells followed by tissue repair are essential processes for disease remission and the successful management of inflammatory bowel disease. In light of the key role of TAMs in controlling inflammatory responses, here, we review the recent advances on TAM research vis-à-vis the resolution of intestinal inflammation. Targeted activation of TAM receptor tyrosine kinases may represent a potent therapeutic opportunity in inflammatory bowel disease.

Oncostatin M reduces lesion size and promotes functional recovery and neurite outgrowth after spinal cord injury

The family of interleukin (IL)-6 like cytokines plays an important role in the neuroinflammatory response to injury by regulating both neural as well as immune responses. Here, we show that expression of the IL-6 family member oncostatin M (OSM) and its receptor is upregulated after spinal cord injury (SCI). To reveal the relevance of increased OSM signaling in the pathophysiology of SCI, OSM was applied locally after spinal cord hemisection in mice. OSM treatment significantly improved locomotor recovery after mild and severe SCI. Improved recovery in OSM-treated mice was associated with a reduced lesion size. OSM significantly diminished astrogliosis and immune cell infiltration. Thus, OSM limits secondary damage after CNS trauma. In vitro viability assays demonstrated that OSM protects primary neurons in culture from cell death, suggesting that the underlying mechanism involves direct neuroprotective effects of OSM. Furthermore, OSM dose-dependently promoted neurite outgrowth in cultured neurons, indicating that the cytokine plays an additional role in CNS repair. Indeed, our in vivo experiments demonstrate that OSM treatment increases plasticity of serotonergic fibers after SCI. Together, our data show that OSM is produced at the lesion site, where it protects the CNS from further damage and promotes recovery.