Comparative Genomic, MicroRNA, and Tissue Analyses Reveal Subtle Differences between Non-Diabetic and Diabetic Foot Skin

Multiomics Analysis Unravels Alteration in Molecule and Pathways Involved in Nondiabetic Chronic Wounds

The prevalence of chronic wounds (CW) continues to grow. A thorough knowledge of the mechanism of CW formation remains elusive due to a lack of relevant studies. Furthermore, most previous studies concentrated on diabetic ulcers with relatively few investigations on other types. We performed this multiomics study to investigate the proteomic and metabolomic changes in wound and surrounding tissue from a cohort containing 13 patients with nondiabetic CW. Differentially expressed proteins (DEPs) and metabolites (DEMs) were filtered out and analyzed through multiomic profiling. The DEPs were further confirmed with the use of parallel reaction monitoring. Compared with the surrounding tissue, there were 82 proteins and 214 metabolites altered significantly in wound tissue. The DEPs were mainly enriched in focal adhesion (FA), extracellular matrix-receptor interaction (ERI), and the PI3K-Akt (PA) signaling pathway. Moreover, the DEMs were significantly enriched in amino sugar and nucleotide sugar metabolism and biosynthesis of nucleotide sugar pathways. In correlation analysis, we discovered that the PA signaling pathway, as well as its upstream and downstream pathways, coenriched some DEPs and DEMs. Additionally, we found that FBLN1, FBLN5, and EFEMP1 (FBLN3) proteins dramatically elevated in wound tissue and connected with the above signaling pathways. This multiomics study found that changes in FA, ERI, and PA signaling pathways had an impact on the cellular activities and functions of wound tissue cells. Additionally, increased expression of those proteins in wound tissue may inhibit vascular and skin cell proliferation and degrade the extracellular matrix, which may be one of the causes of CW formation.

Keratin isoform shifts modulate motility signals during wound healing

Keratin intermediate filaments form strong mechanical scaffolds that confer structural stability to epithelial tissues, but the reason this function requires a protein family with 54 isoforms is not understood. During skin wound healing, a shift in keratin isoform expression alters the composition of keratin filaments. How this change modulates cellular function to support epidermal remodeling remains unclear. We report an unexpected effect of keratin isoform variation on kinase signal transduction. Increased expression of wound-associated keratin 6A, but not of steady-state keratin 5, potentiated keratinocyte migration and wound closure without compromising epidermal stability by activating myosin motors. This pathway depended on isoform-specific interaction between intrinsically disordered keratin head domains and non-filamentous vimentin shuttling myosin-activating kinases. These results substantially expand the functional repertoire of intermediate filaments from their canonical role as mechanical scaffolds to include roles as isoform-tuned signaling scaffolds that organize signal transduction cascades in space and time to influence epithelial cell state.

Cutaneous changes in diabetic patients: Primed for aberrant healing?

Cutaneous manifestations affect most patients with diabetes mellitus, clinically presenting with numerous dermatologic diseases from xerosis to diabetic foot ulcers (DFUs). Skin conditions not only impose a significantly impaired quality of life on individuals with diabetes but also predispose patients to further complications. Knowledge of cutaneous biology and the wound healing process under diabetic conditions is largely limited to animal models, and studies focusing on biology of the human condition of DFUs remain limited. In this review, we discuss the critical molecular, cellular, and structural changes to the skin in the hyperglycaemic and insulin-resistant environment of diabetes with a focus specifically on human-derived data. Elucidating the breadth of the cutaneous manifestations coupled with effective diabetes management is important for improving patient quality of life and averting future complications including wound healing disorders.

The role of microRNAs in pathophysiology and diagnostics of metabolic complications in obstructive sleep apnea patients

Obstructive sleep apnea (OSA) is one of the most common sleep disorders, which is characterized by recurrent apneas and/or hypopneas occurring during sleep due to upper airway obstruction. Among a variety of health consequences, OSA patients are particularly susceptible to developing metabolic complications, such as metabolic syndrome and diabetes mellitus type 2. MicroRNAs (miRNAs) as epigenetic modulators are promising particles in both understanding the pathophysiology of OSA and the prediction of OSA complications. This review describes the role of miRNAs in the development of OSA-associated metabolic complications. Moreover, it summarizes the usefulness of miRNAs as biomarkers in predicting the aforementioned OSA complications.

Protecting human amnion and chorion matrices during processing: Performance enhancement in a diabetic mouse model and human co-culture system

Recent evidence suggests that protecting human amnion and chorion matrices (HACM) during processing enhances the performance of HACM for wound repair and tissue regeneration. We utilised a diabetic (db/db) delayed wound healing mouse model. Treatment of db/db full-thickness excisional wounds with HACM, processed with a polyampholyte preservative accentuated the proliferative phase of wound healing that decreased the time necessary to heal wounds. Polyampholyte protection improved the preservation of growth factors and cytokines during room temperature storage following E-beam sterilisation and improved its function in wound healing applications. Our findings indicate protected HACM tissue up-regulated MIP2, NF-kB, TNF-α, KI-67, and Arg1 (0.6-fold to 1.5-fold) but those changes were not statistically significant. Immunofluorescent assessment identifying cell activity illustrated an induction of the proliferative phase of wound healing and a switch from an inflammatory macrophage phenotype (M1) to a pro-regenerative macrophage phenotype (M2a). Genomic profiling of 282 genes was performed using Nanostring from co-cultures of human macrophages and fibroblasts. The polyampholyte + HACM-treated group, compared with the HACM or polyampholyte alone groups, had a statistically significant up-regulation (32-368 fold) of 12 genes primarily involved in macrophage plasticity including CLC7, CD209, CD36, HSD11B1, ICAM1, IL1RN, IL3RA, ITGAX, LSP1, and PLXDC2 (adj. p-value < 0.05). The polyampholyte alone group demonstrated statistically significant down-regulation of four genes ADRA2, COL7A1, CSF3, and PTGS2 (adj. p < 0.05). The HACM alone group up-regulated four genes ATG14, CXCL11, DNMT3A, and THBD, but the results were not statistically significant. Biomechanical measurements indicated that wounds treated with polyampholyte-protected HACM had more tensile integrity compared with wounds treated with HACM alone. These findings indicate that better protection of HACM during processing stabilises the HACM matrix, which may lead to improved wound healing outcomes.

Molecular Pathophysiology of Chronic Wounds: Current State and Future Directions

Venous leg ulcers, diabetic foot ulcers, and pressure ulcers are complex chronic wounds with multifactorial etiologies that are associated with high patient morbidity and mortality. Despite considerable progress in deciphering the pathologies of chronic wounds using "omics" approaches, considerable gaps in knowledge remain, and current therapies are often not efficacious. We provide a comprehensive overview of current understanding of the molecular mechanisms that impair healing and current knowledge on cell-specific dysregulation including keratinocytes, fibroblasts, immune cells, endothelial cells and their contributions to impaired reepithelialization, inflammation, angiogenesis, and tissue remodeling that characterize chronic wounds. We also provide a rationale for further elucidation of ulcer-specific pathologic processes that can be therapeutically targeted to shift chronic nonhealing to acute healing wounds.

Personalized Scaffolds for Diabetic Foot Ulcer Healing Using Extracellular Matrix from Induced Pluripotent Stem-Reprogrammed Patient Cells

Diabetic foot ulcers (DFU) are chronic wounds sustained by pathological fibroblasts and aberrant extracellular matrix (ECM). Porous collagen-based scaffolds (CS) have shown clinical promise for treating DFUs but may benefit from functional enhancements. Our previous work showed fibroblasts differentiated from induced pluripotent stem cells are an effective source of new ECM mimicking fetal matrix, which notably promotes scar-free healing. Likewise, functionalizing CS with this rejuvenated ECM showed potential for DFU healing. Here, we demonstrate for the first time an approach to DFU healing using biopsied cells from DFU patients, reprogramming those cells, and functionalizing CS with patient-specific ECM as a personalized acellular tissue engineered scaffold. We took a two-pronged approach: 1) direct ECM blending into scaffold fabrication; and 2) seeding scaffolds with reprogrammed fibroblasts for ECM deposition followed by decellularization. The decellularization approach reduced cell number requirements and maintained naturally deposited ECM proteins. Both approaches showed enhanced ECM deposition from DFU fibroblasts. Decellularized scaffolds additionally enhanced glycosaminoglycan deposition and subsequent vascularization. Finally, reprogrammed ECM scaffolds from patient-matched DFU fibroblasts outperformed those from healthy fibroblasts in several metrics, suggesting ECM is in fact able to redirect resident pathological fibroblasts in DFUs towards healing, and a patient-specific ECM signature may be beneficial.

Evolving spectrum of diabetic wound: Mechanistic insights and therapeutic targets

Diabetes mellitus is a chronic metabolic disorder resulting in an increased blood glucose level and prolonged hyperglycemia, causes long term health conse-quences. Chronic wound is frequently occurring in diabetes patients due to compromised wound healing capability. Management of wounds in diabetic patients remains a clinical challenge despite many advancements in the field of science and technology. Increasing evidence indicates that alteration of the biochemical milieu resulting from alteration in inflammatory cytokines and matrix metalloproteinase, decrease in fibroblast and keratinocyte functioning, neuropathy, altered leukocyte functioning, infection, etc., plays a significant role in impaired wound healing in diabetic people. Apart from the current pharmacotherapy, different other approaches like the use of conventional drugs, antidiabetic medication, antibiotics, debridement, offloading, platelet-rich plasma, growth factor, oxygen therapy, negative pressure wound therapy, low-level laser, extracorporeal shock wave bioengineered substitute can be considered in the management of diabetic wounds. Drugs/therapeutic strategy that induce angiogenesis and collagen synthesis, inhibition of MMPs, reduction of oxidative stress, controlling hyperglycemia, increase growth factors, regulate inflammatory cytokines, cause NO induction, induce fibroblast and keratinocyte proliferation, control microbial infections are considered important in controlling diabetic wound. Further, medicinal plants and/or phytoconstituents also offer a viable alternative in the treatment of diabetic wound. The focus of the present review is to highlight the molecular and cellular mechanisms, and discuss the drug targets and treatment strategies involved in the diabetic wound.

Dichotomous role of miR193b-3p in diabetic foot ulcers maintains inhibition of healing and suppression of tumor formation

Despite the hyperproliferative environment marked by activation of β-catenin and overexpression of c-myc, the epidermis surrounding chronic diabetic foot ulcers (DFUs) is clinically hypertrophic and nonmigratory yet does not undergo malignant transformation. We identified miR193b-3p as a master regulator that contributes to this unique cellular phenotype. We determined that induction of tumor suppressor miR193b-3p is a unique feature of DFUs that is not found in venous leg ulcers, acute wounds, or cutaneous squamous cell carcinoma (SCC). Genomic analyses of DFUs identified suppression of the miR193b-3p target gene network that orchestrates cell motility. Inhibition of migration and wound closure was further confirmed by overexpression of miR193b-3p in human organotypic and murine in vivo wound models, whereas miR193b-3p knockdown accelerated wound reepithelialization in human ex vivo and diabetic murine wounds in vivo. The dominant negative effect of miR193b-3p on keratinocyte migration was maintained in the presence of promigratory miR31-5p and miR15b-5p, which were also overexpressed in DFUs. miR193b-3p mediated antimigratory activity by disrupting stress fiber formation and by decreasing activity of GTPase RhoA. Conversely, miR193b-3p targets that typically participate in malignant transformation were found to be differentially regulated between DFUs and SCC, including the proto-oncogenes KRAS (Kirsten rat sarcoma viral proto-oncogene) and KIT (KIT proto-oncogene). Although miR193b-3p acts as a tumor suppressor contributing to low tumor incidence in DFUs, it also acts as a master inhibitor of cellular migration and epithelialization in DFUs. Thus, miR193b-3p may represent a target for wound healing induction, cancer therapeutics, and diagnostics.

Bioinformatic Analysis Reveals Hub Immune-Related Genes of Diabetic Foot Ulcers

Diabetic foot ulcer (DFU) is a complex and devastating complication of diabetes mellitus that are usually stagnant in the inflammatory phase. However, oral wound healing, which is characterized by a rapid and scarless healing process, is regarded an ideal model of wound healing. Thus, we performed a comprehensive bioinformatics analysis of the previously published data regarding oral ulcers and DFUs and found that compared to oral wound healing, the activated pathways of DFUs were enriched in cellular metabolism-related pathways but lacked the activation of inflammatory and immune-related pathways. We also found that CXCL11, DDX60, IFI44, and IFI44L were remarkable nodes since they had the most connections with other members of the module. Meanwhile, CXCL10, IRF7, and DDX58 together formed a closed-loop relationship and occupied central positions in the entire network. The real-time polymerase chain reaction and western blot was applied to validate the gene expression of the hub immune-related genes in the DFU tissues, it was found that CXCL11, IFI44, IFI44L, CXCL10 and IRF7 have a significant difference compared with normal wound tissues. Our research reveals some novel potential immune-related biomarkers and provides new insights into the molecular basis of this debilitating disease.

The Construction and Analysis of Infiltrating Immune Cell and ceRNA Networks in Diabetic Foot Ulcer

BACKGROUND

Diabetic foot ulcer (DFU) is a severe complication characterized by low-grade infectious inflammation and probably associated with specific competitive endogenous RNAs (ceRNAs) and infiltrating immune cells. Nonetheless, no reliable biomarkers are used for detecting infectious inflammation in DFU. Therefore, it is essential to explore potential biomarkers for the accurate diagnosis and treatment of DFU.

METHODS

The gene expression profile was retrieved from Gene Expression Omnibus (GEO) database and divided into two groups, namely, standard samples and DFU samples. To establish the ceRNA networks, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were utilized to analyze differential expression genes (DEGs). The cell type identification was achieved by estimating relative subsets of RNA transcripts (CIBERSORT) algorithm to screen-specific immune-infiltrating cells associated with DFU.

RESULTS

A ceRNA network was constructed with 20 differential expression circRNA (DEcircRNAs), 11 differential expression microRNAs (DEmiRNAs), and 9 differential expression mRNAs (DEmRNAs). Functional enrichment analysis demonstrated that DFU was mainly enriched in vascular endothelial growth factor (VEGF) and T-cell receptor signaling. In addition, CIBERSORT estimation indicated that CD8⁺ T cells and Monocytes were significantly related to the expression of IL-6, a DFU-specific infectious inflammation factor.

CONCLUSION

This study identified that some significant ceRNAs (JUNB, GATA3, hsa-circ-0049271 and hsa-circ-0074559) and infiltrating immune cells (CD8⁺ T cells and monocytes) might be related to DFU infectious inflammation.

Recovery of Altered Diabetic Myofibroblast Heterogeneity and Gene Expression Are Associated with CD301b+ Macrophages

Diabetic wound healing is associated with impaired function and reduced numbers of myofibroblasts, a heterogeneous cell population with varying capacities to promote repair. To determine how diabetes alters myofibroblast composition, we performed flow cytometry and spatial tissue analysis of myofibroblast subsets throughout the healing process in diabetic (db/db) and control (db/+) mouse skin. We observed reduced numbers of profibrotic SCA1+; CD34+; CD26+ myofibroblasts in diabetic wounds five days after injury, with decreased expression of fibrosis-associated genes compared to myofibroblasts from db/+ mouse wounds. While the abundance of myofibroblasts remained reduced in db/db mouse wounds compared to controls, the altered myofibroblast heterogeneity and gene expression in diabetic mice was improved seven days after injury. The natural correction of myofibroblast composition and gene expression in db/db wound beds temporally corresponds with a macrophage phenotypic switch. Correlation analysis from individual wound beds revealed that wound healing in control mice is associated with CD206+ macrophages, while the rescued myofibroblast phenotypes in diabetic wounds are correlated with increased CD301b+ macrophage numbers. These data demonstrate how diabetes impacts specific subsets of myofibroblasts and indicate that signaling capable of rescuing impaired diabetic wound healing could be different from signals that regulate wound healing under nonpathological conditions.

Intracellular Staphylococcus aureus triggers pyroptosis and contributes to inhibition of healing due to Perforin-2 suppression

Impaired wound healing associated with recurrent Staphylococcus aureus infection and unresolved inflammation are hallmarks of non-healing diabetic foot ulcers (DFU). Perforin-2, an innate immunity molecule against intracellular bacteria, limits cutaneous infection and dissemination of S. aureus in mice. Here we report the intracellular accumulation of S. aureus in the epidermis of DFU with no clinical signs of infection due to marked suppression of Perforin-2. S. aureus residing within the epidermis of DFU triggers AIM2-inflammasome activation and pyroptosis. These findings were corroborated in mice lacking Perforin-2. The effects of pyroptosis on DFU clinical outcomes were further elucidated in a 4-week longitudinal clinical study in DFU patients undergoing standard of care. Increased AIM2-inflammasome and ASC-pyroptosome coupled with induction of IL-1β were found in non-healing when compared to healing DFU. Our findings reveal novel mechanism that includes Perforin-2 suppression, intracellular S. aureus accumulation and associated induction of pyroptosis that contribute to healing inhibition and prolonged inflammation in patients with DFU.

Glucocorticoid-mediated induction of caveolin-1 disrupts cytoskeletal organization, inhibits cell migration and re-epithelialization of non-healing wounds

Although impaired keratinocyte migration is a recognized hallmark of chronic wounds, the molecular mechanisms underpinning impaired cell movement are poorly understood. Here, we demonstrate that both diabetic foot ulcers (DFUs) and venous leg ulcers (VLUs) exhibit global deregulation of cytoskeletal organization in genomic comparison to normal skin and acute wounds. Interestingly, we found that DFUs and VLUs exhibited downregulation of ArhGAP35, which serves both as an inactivator of RhoA and as a glucocorticoid repressor. Since chronic wounds exhibit elevated levels of cortisol and caveolin-1 (Cav1), we posited that observed elevation of Cav1 expression may contribute to impaired actin-cytoskeletal signaling, manifesting in aberrant keratinocyte migration. We showed that Cav1 indeed antagonizes ArhGAP35, resulting in increased activation of RhoA and diminished activation of Cdc42, which can be rescued by Cav1 disruption. Furthermore, we demonstrate that both inducible keratinocyte specific Cav1 knockout mice, and MβCD treated diabetic mice, exhibit accelerated wound closure. Taken together, our findings provide a previously unreported mechanism by which Cav1-mediated cytoskeletal organization prevents wound closure in patients with chronic wounds.

Cellular reprogramming of diabetic foot ulcer fibroblasts triggers pro-healing miRNA-mediated epigenetic signature

Diabetic foot ulcers (DFUs), a prevalent complication of diabetes, constitute a major medical challenge with a critical need for development of cell-based therapies. We previously generated induced pluripotent stem cells (iPSCs) from dermal fibroblasts derived from the DFU patients, location-matched skin of diabetic patients and normal healthy donors and re-differentiated them into fibroblasts. To assess the epigenetic microRNA (miR) regulated changes triggered by cellular reprogramming, we performed miRs expression profiling. We found let-7c, miR-26b-5p, -29c-3p, -148a-3p, -196a-5p, -199b-5p and -374a-5p suppressed in iPSC-derived fibroblasts in vitro and in 3D dermis-like self-assembly tissue, whereas their corresponding targets involved in cellular migration were upregulated. Moreover, targets involved in organization of extracellular matrix were induced after fibroblast reprogramming. PLAT gene, the crucial fibrinolysis factor, was upregulated in iPSC-derived fibroblasts and was confirmed as a direct target of miR-196a-5p. miR-197-3p and miR-331-3p were found upregulated specifically in iPSC-derived diabetic fibroblasts, while their targets CAV1 and CDKN3 were suppressed. CAV1, an important negative regulator of wound healing, was confirmed as a direct miR-197-3p target. Together, our findings demonstrate that iPSC reprogramming is an effective approach for erasing the diabetic non-healing miR-mediated epigenetic signature and promoting a pro-healing cellular phenotype.

The progress, prospects, and challenges of the use of non-coding RNA for diabetic wounds

Chronic diabetic wounds affect the quality of life of patients, resulting in significant social and economic burdens on both individuals and the health care system. Although treatment methods for chronic diabetic wounds have been explored, there remains a lack of effective treatment strategies; therefore, alternative strategies must be explored. Recently, the abnormal expression of non-coding RNA in diabetic wounds has received widespread attention since it is an important factor in the development of diabetic wounds. This article reviews the regulatory role of three common non-coding RNAs (microRNA [miRNA], long non-coding RNA [lncRNA], and circular RNA [circRNA]) in diabetic wounds and discusses the diagnosis, treatment potential, and challenges of non-coding RNA in diabetic wounds. This article provides insights into new strategies for diabetic wound diagnosis and treatment at the genetic and molecular levels.

Intralesional Infiltrations of Cell-Free Filtrates Derived from Human Diabetic Tissues Delay the Healing Process and Recreate Diabetes Histopathological Changes in Healthy Rats

Lower limb ulcers in type-2 diabetic patients are a frequent complication that tributes to amputation and reduces survival. We hypothesized that diabetic healing impairment and other histopathologic hallmarks are mediated by a T2DM-induced tissue priming/metabolic memory that can be transferred from humans to healthy recipient animals and consequently reproduce diabetic donor’s phenotypes. We examined the effect of human T2DM tissue homogenates injected into non-diabetic rat excisional wounds. Fresh granulation tissue, popliteal artery, and peroneal nerve of patients with T2DM were obtained following amputation. Post-mammoplasty granulation and post-traumatic amputation-tissue of normal subjects acted as controls. The homogenates were intralesionally injected for 6–7 days into rats’ excisional thickness wounds. Infiltration with the different homogenates caused impaired wound closure, inflammation, nerve degeneration, and arterial thickening (all P &lt; 0.01 vs relevant control) resembling histopathology of diabetic donor tissues. Control materials caused marginal inflammation only. Infiltration with glycated bovine albumin provoked inflammation and wound healing delay but did not induce arterial thickening. The reproduction of human diabetic traits in healthy recipient animals through a tissue homogenate support the notion on the existence of tissue metabolic memory-associated and transmissible factors, involved in the pathogenesis of diabetic complications. These may have futuristic clinical implications for medical interventions.

The Development of Tissue Engineering Scaffolds Using Matrix from iPS-Reprogrammed Fibroblasts

Tissue engineering solutions have been widely explored for enhanced healing of skin wounds. Diabetic foot ulcers (DFU) are particularly challenging wounds to heal for a variety of reasons, including aberrant ECM, dysregulation of vascularization, and persistent inflammation. Tissue engineering approaches, such as porous collagen-based scaffolds, have shown promise in replacing the current treatments of surgical debridement and topical treatments. Collagen-glycosaminoglycan scaffolds, which are FDA approved for diabetic foot ulcers, can benefit from further functionalization by incorporation of additional signaling factors or extracellular matrix molecules. One option for this is to incorporate matrix from a rejuvenated cell source, as wounds in younger patients heal more quickly. Induced pluripotent stem cells (iPS) are generated from somatic cells and share many functional similarities with embryonic stem cells (ES), while avoiding the ethical concerns. Fibroblasts differentiated from iPS cells have been shown to enrich their ECM with glycosaminoglycan (GAGs), collagen Type III and fibronectin, to have an increased ECM production, and to be pro-angiogenic. Here we describe a technique to grow matrix from post-iPS fibroblasts, and to develop a scaffold from this matrix, in combination with collagen, with the goal of enhancing wound healing. By activating scaffolds with extracellular matrix (ECM) from fibroblasts derived from an iPS source (post-iPSF), the scaffolds are enriched with beneficial elements like GAGs, collagen type III, fibronectin, and VEGF. We believe these scaffolds can enhance skin regeneration and that the techniques can be modified for other tissue engineering applications.

Integrated Bioinformatics-Based Identification of Potential Diagnostic Biomarkers Associated with Diabetic Foot Ulcer Development

The present study was designed to detect possible biomarkers associated with diabetic foot ulcer (DFU) incidence in an effort to develop novel treatments for this condition. The GSE7014 and GSE29221 gene expression datasets were downloaded from the Gene Expression Omnibus (GEO) database, after which differentially expressed genes (DEGs) were identified between DFU and healthy samples. These DEGs were then arranged into a protein-protein interaction (PPI) network, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) term enrichment analyses were performed to explore the functional roles of these genes. In total, 1192 DEGs were identified in the GSE7014 dataset (900 upregulated, 292 downregulated), while 1177 were identified in the GSE29221 dataset (257 upregulated, 919 downregulated). GO analyses revealed these DEGs to be significantly enriched in biological processes including sarcomere organization, muscle filament sliding, and the regulation of cardiac conduction, molecular functions including structural constituent of muscle, protein binding, and calcium ion binding, and cellular components including Z disc, myosin filament, and M band. These DEGs were also enriched in the adrenergic signaling in cardiomyoctes, dilated cardiomyopathy, and tight junction KEGG pathways. Together, the findings of these bioinformatics analyses thus identified key hub genes associated with DFU development.

Long noncoding RNA H19 acts as a miR-29b sponge to promote wound healing in diabetic foot ulcer

Aberrant expression of long noncoding RNA (lncRNA) H19 and microRNA (miR)-29b has been implicated in the complications of diabetes mellitus (DM). As a common and important complication of DM, diabetic foot ulcer (DFU) is characterized by high incidence and poor prognosis. Herein, we explored the role of lncRNA H19 in wound healing of DFU. Differentially expressed DM-related lncRNAs were initially screened by microarray data analysis. DFU models were then induced in DM mouse models. The functional role and interaction of lncRNA H19, miR-29b and FBN1 in DFU were subsequently determined by examining the proliferation, migration, and apoptosis of fibroblasts after silencing H19, inhibiting or overexpressing miR-29b and FBN1. According to microarray-based analysis, lncRNA H19 was upregulated in DM. In the ulcerative edge tissues of DFU, high expression of lncRNA H19 and FBN1 and low expression of miR-29b were observed. FBN1 was identified to be a target gene of miR-29b. LncRNA H19 could competitively bind to miR-29b, and then, inhibited its expression, which consequently upregulating FBN1. Silencing of lncRNA H19 led to inhibited proliferation, migration, and enhanced apoptosis of fibroblasts, accompanied by downregulated FBN1 but upregulated miR-29b, which diminished the expression of TGF-β1, Smad3, FN, and Col-1 and reduced extracellular matrix accumulation. Altogether, upregulation of lncRNA H19 can elevate the expression of FBN1 through competitively binding to miR-29b, which enhances the proliferation, migration, and inhibits apoptosis of fibroblasts, thus facilitating the wound healing of DFU.

The lubricating effect of iPS-reprogrammed fibroblasts on collagen-GAG scaffolds for cartilage repair applications

Tissue engineering products, like collagen-glycosaminoglycan scaffolds, have been successfully applied to chondrogenic defects. Inducible Pluripotent Stem cell (iPS) technology allows reprograming of somatic cells into an embryonic-like state, allowing for redifferentiation. We postulated that a fibroblast cell line (BJ cells - 'pre-iPSF') cycled through iPS reprogramming and redifferentiated into fibroblasts (post-iPSF) could lubricate collagen-glycosaminoglycan scaffolds; fibroblasts are known to produce lubricating molecules (e.g., lubricin) in the synovium. Herein, we quantified the coefficient of friction (CoF) of collagen-glycosaminoglycan scaffolds seeded with post-iPSF; tested whether cell-free scaffolds made of post-iPSF derived extracellular matrix had reduced friction vs. pre-iPSF; and assessed lubricin quantity as a possible protein responsible for lubrication. Post-iPSF seeded CG had 6- to 10-fold lower CoF versus pre-iPSF. Scaffolds consisting of a collagen and pre-/post-iPSF extracellular matrix blend outperformed these cell-seeded scaffolds (~5-fold lower CoF), yielding excellent CoF values close to synovial fluid. Staining revealed an increased presence of lubricin within post-iPSF scaffolds (confirmed by western blotting) and on the surface of iPSF-seeded collagen-glycosaminoglycan scaffolds. Interestingly, when primary cells from patient biopsy-derived fibroblasts were used, iPS reprogramming did not further reduce the already low CoF of these cells and no lubricin expression was found. We conclude that iPS reprogramming activates lubricating properties in iPS-derived cells in a source cell-specific manner. Additionally, lubricin appears to play a lubricating role, yet other proteins also contribute to lubrication. This work constitutes an important step for understanding post-iPSF lubrication of scaffolds and its potential for cartilage tissue engineering.

Notch1 signaling determines the plasticity and function of fibroblasts in diabetic wounds

Fibroblasts play a pivotal role in wound healing. However, the molecular mechanisms determining the reparative response of fibroblasts remain unknown. Here, we identify Notch1 signaling as a molecular determinant controlling the plasticity and function of fibroblasts in modulating wound healing and angiogenesis. The Notch pathway is activated in fibroblasts of diabetic wounds but not in normal skin and non-diabetic wounds. Consistently, wound healing in the FSP-1 ^+/- ;ROSA ^LSL-N1IC+/+ mouse, in which Notch1 is activated in fibroblasts, is delayed. Increased Notch1 activity in fibroblasts suppressed their growth, migration, and differentiation into myofibroblasts. Accordingly, significantly fewer myofibroblasts and less collagen were present in granulation tissues of the FSP-1 ^+/- ;ROSA ^LSL-N1IC+/+ mice, demonstrating that high Notch1 activity inhibits fibroblast differentiation. High Notch1 activity in fibroblasts diminished their role in modulating the angiogenic response. We also identified that IL-6 is a functional Notch1 target and involved in regulating angiogenesis. These findings suggest that Notch1 signaling determines the plasticity and function of fibroblasts in wound healing and angiogenesis, unveiling intracellular Notch1 signaling in fibroblasts as potential target for therapeutic intervention in diabetic wound healing.

Mechanistic Actions of microRNAs in Diabetic Wound Healing

Wound healing is a complex biological process that is impaired under diabetes conditions. Chronic non-healing wounds in diabetes are some of the most expensive healthcare expenditures worldwide. Early diagnosis and efficacious treatment strategies are needed. microRNAs (miRNAs), a class of 18–25 nucleotide long RNAs, are important regulatory molecules involved in gene expression regulation and in the repression of translation, controlling protein expression in health and disease. Recently, miRNAs have emerged as critical players in impaired wound healing and could be targets for potential therapies for non-healing wounds. Here, we review and discuss the mechanistic background of miRNA actions in chronic wounds that can shed the light on their utilization as specific wound healing biomarkers.

Deregulated immune cell recruitment orchestrated by FOXM1 impairs human diabetic wound healing

Diabetic foot ulcers (DFUs) are a life-threatening disease that often result in lower limb amputations and a shortened lifespan. However, molecular mechanisms contributing to the pathogenesis of DFUs remain poorly understood. We use next-generation sequencing to generate a human dataset of pathogenic DFUs to compare to transcriptional profiles of human skin and oral acute wounds, oral as a model of “ideal” adult tissue repair due to accelerated closure without scarring. Here we identify major transcriptional networks deregulated in DFUs that result in decreased neutrophils and macrophages recruitment and overall poorly controlled inflammatory response. Transcription factors FOXM1 and STAT3, which function to activate and promote survival of immune cells, are inhibited in DFUs. Moreover, inhibition of FOXM1 in diabetic mouse models (STZ-induced and db/db) results in delayed wound healing and decreased neutrophil and macrophage recruitment in diabetic wounds in vivo. Our data underscore the role of a perturbed, ineffective inflammatory response as a major contributor to the pathogenesis of DFUs, which is facilitated by FOXM1-mediated deregulation of recruitment of neutrophils and macrophages, revealing a potential therapeutic strategy.

Diabetic foot ulcers (DFU) represent a complex disease with limited treatment options. Here, the authors compare human RNASeq patient data from DFU, oral mucosa and skin acute wounds, identifying FOXM1 as a mediator of macrophage and neutrophil recruitment, which contributes to disease pathogenesis and is dysregulated in patients.

Identification of stress-related microRNA biomarkers in type 2 diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Many studies have investigated microRNAs (miRNAs) in the detection of type 2 diabetes mellitus (T2DM). Herein, the dysregulated direction of stress-related miRNAs used as biomarkers of T2DM are summarized and analyzed.

METHODS

PubMed, EMBASE, ISI Web of Science, and three Chinese databases were searched for case-control miRNA profiling studies about T2DM. A meta-analysis under a random effect was performed. Subgroup analysis was conducted based on different tissues and species. Sensitivity analysis was conducted to confirm the robustness among studies. The effect size was pooled using ln odds ratios (ORs), 95% confidence intervals (95% CIs), and P-values.

RESULTS

The present meta-analysis included 39 case-control studies with a total of 494 miRNAs. Only 33 miRNAs were reported in three or more studies and, of these, 18 were inconsistent in their direction of dysregulation. Two significantly dysregulated miRNAs (let-7 g and miR-155) were identified in the meta-analysis. Four miRNAs (miR-142-3p, miR-155, miR-21, and miR-34c-5p) were dysregulated in patients with T2DM, whereas five miRNAs (miR-146a, miR-199a-3p, miR-200b, miR-29b and miR-30e) were dysregulated in animal models of diabetes. In addition, two dysregulated miRNAs (miR-146a and miR-21) were highly cornea specific and heart specific. In sensitivity analysis, only miR-155 was still significantly dysregulated after removing studies with small sample sizes.

CONCLUSIONS

The present meta-analysis revealed that 16 stress-related miRNAs were significantly dysregulated in T2DM. MiR-148b, miR-223, miR-130a, miR-19a, miR-26b and miR-27b were selected as potential circulating biomarkers of T2DM. In addition, miR-146a and miR-21 were identified as potential tissue biomarkers of T2DM.

Genome wide analysis of gene expression changes in skin from patients with type 2 diabetes

Non-healing chronic ulcers are a serious complication of diabetes and are a major healthcare problem. While a host of treatments have been explored to heal or prevent these ulcers from forming, these treatments have not been found to be consistently effective in clinical trials. An understanding of the changes in gene expression in the skin of diabetic patients may provide insight into the processes and mechanisms that precede the formation of non-healing ulcers. In this study, we investigated genome wide changes in gene expression in skin between patients with type 2 diabetes and non-diabetic patients using next generation sequencing. We compared the gene expression in skin samples taken from 27 patients (13 with type 2 diabetes and 14 non-diabetic). This information may be useful in identifying the causal factors and potential therapeutic targets for the prevention and treatment of diabetic related diseases.

miR-190-5p in human diseases

miRNAs, a major class of small noncoding RNAs approximately 18-25 nucleotides in length, function by repressing the expression of target genes through binding to complementary sequences in the 3'-UTRs of target genes. Emerging evidence has highlighted their important roles in numerous diseases, including human cancers. Recently, miR-190 has been shown to be dysregulated in various types of human cancers that participates in cancer-related biological processes, including proliferation, apoptosis, metastasis, drug resistance, by regulating associated target genes, and to predict cancer diagnosis and prognosis. In this review, we summarized the roles of miR-190-5p in human diseases, especially in human cancers. Then we classified its target genes in tumorigenesis and progression, which might provide evidence for cancer diagnosis and prognosis, promising tools for cancer treatment, or leads for further investigation.

Co-expression network analysis revealing the key lncRNAs in diabetic foot ulcers

INTRODUCTION

Diabetic foot ulcers (DFUs) are the most common foot injuries leading to lower extremity amputation in diabetic patients. Recent studies showed that long non-coding RNAs (lncRNAs) played important roles in diverse biological processes. In this study, we focused on identifying differentially expressed long non-coding RNAs (lncRNAs) in DFU.

MATERIAL AND METHODS

Real-time PCR assay was performed to validate the expression pattern of lncRNAs in DFU. Moreover, co-expression networks were also constructed to identify hub lncRNAs in DFU. Specifically, gene ontology (GO) analysis was first performed to evaluate the potential roles of differentially expressed genes (DEGs) and lncRNAs in DFU.

RESULTS

In the present study, we identified 58 up-regulated lncRNAs and 42 down-regulated lncRNAs in DFU samples compared to non-diabetic foot skin samples by analyzing the GSE68186 dataset. Four lncRNAs (FLJ30679, LINC01193, LINC00692, and LINC00641) were observed to be up-regulated in DFU. Furthermore, we found that the down-regulated lncRNA-mediated co-expression network contained 42 lncRNAs and 700 DEGs and the up-regulated lncRNA mediated co-expression network contained 58 lncRNAs and 688 DEGs.

CONCLUSIONS

Bioinformatics analysis showed that differentially expressed lncRNAs were involved in regulating the ERK1 and ERK2 cascade, secondary alcohol biosynthetic process, centrosome duplication and DNA repair. These results suggested the potential prognostic value of lncRNAs in DFU.

Pharmacological and Genetic Inhibition of Caveolin-1 Promotes Epithelialization and Wound Closure

Chronic wounds-including diabetic foot ulcers, venous leg ulcers, and pressure ulcers-represent a major health problem that demands an urgent solution and new therapies. Despite major burden to patients, health care professionals, and health care systems worldwide, there are no efficacious therapies approved for treatment of chronic wounds. One of the major obstacles in achieving wound closure in patients is the lack of epithelial migration. Here, we used multiple pre-clinical wound models to show that Caveolin-1 (Cav1) impedes healing and that targeting Cav1 accelerates wound closure. We found that Cav1 expression is significantly upregulated in wound edge biopsies of patients with non-healing wounds, confirming its healing-inhibitory role. Conversely, Cav1 was absent from the migrating epithelium and is downregulated in acutely healing wounds. Specifically, Cav1 interacted with membranous glucocorticoid receptor (mbGR) and epidermal growth factor receptor (EGFR) in a glucocorticoid-dependent manner to inhibit cutaneous healing. However, pharmacological disruption of caveolae by MβCD or CRISPR/Cas9-mediated Cav1 knockdown resulted in disruption of Cav1-mbGR and Cav1-EGFR complexes and promoted epithelialization and wound healing. Our data reveal a novel mechanism of inhibition of epithelialization and wound closure, providing a rationale for pharmacological targeting of Cav1 as potential therapy for patients with non-healing chronic wounds.

Single cell analyses reveal specific distribution of anti-bacterial molecule Perforin-2 in human skin and its modulation by wounding and Staphylococcus aureus infection

Perforin-2 (P-2) is a recently described antimicrobial protein with unique properties to kill intracellular bacteria. We investigated P-2 expression pattern and cellular distribution in human skin and its importance in restoration of barrier function during wound healing process and infection with the common wound pathogen Staphylococcus aureus. We describe a novel approach for the measurement of P-2 mRNA within individual skin cells using an amplified fluorescence in situ hybridization (FISH) technique. The unique aspect of this approach is simultaneous detection of P-2 mRNA in combination with immune-phenotyping for cell surface proteins using fluorochrome-conjugated antibodies. We detected P-2 transcript in both hematopoietic (CD45⁺ ) and non-hematopoietic (CD45^- ) cutaneous cell populations, confirming the P-2 expression in both professional and non-professional phagocytes. Furthermore, we found an induction of P-2 during wound healing. P-2 overexpression resulted in a reduction of intracellular S. aureus, while infection of human wounds by this pathogen resulted in P-2 suppression, revealing a novel mechanism by which S. aureus may escape cutaneous immunity to cause persistent wound infections.

MicroRNA-193a Downregulates HMGB1 to Alleviate Diabetic Neuropathic Pain in a Mouse Model

BACKGROUND

Diabetic neuropathy is a serious complication for diabetic patients involving the nervous system. This disease is a quiet but painful condition caused by chronically high blood glucose levels. It is reported that high mobility group box 1 protein (HMGB1) participates in the development of neuropathic pain. This study aimed to explore the role of microRNA (miR)-193a in diabetic neuropathic pain through the regulation of HMGB1.

METHODS

A diabetic mouse model was established through the injection of streptozocin (STZ). Neuropathic pain development was shown by paw withdrawal thresholds and paw withdrawal latency. Expression levels of relative genes or miR were analyzed by qRT-PCR, while Western blot was employed to assess the protein levels. The interaction between miR-193a and HMGB1 mRNA 3'-UTR region was shown by luciferase assay. The levels of inflammation cytokines were measured by ELISA kits.

RESULTS

miR-193a expression was decreased and HMGB1 expression was upregulated in the lumbar spinal dorsal horn of STZ-induced diabetic mice. miR-193a inhibited HMGB1 expression in the lumbar spinal dorsal horn. Overexpression of miR-193a alleviated neuropathic pain in STZ-induced diabetic mice. Peripheral neuroinflammation in diabetic mice was suppressed by miR-193a overexpression.

CONCLUSION

This research illustrates that miR-193a alleviates diabetic neuropathic pain in a mouse model through the inhibition of HMGB1 expression.

MicroRNAs in diabetic wound healing: Pathophysiology and therapeutic opportunities

Diabetic wound healing is an incompletely understood pathophysiological state. It comprises a range of potentially devastating and common complications of diabetes mellitus (DM) leading to intractable infections, lower extremity amputations, and associated cardiovascular morbidity and mortality. MicroRNAs (miRNAs) have emerged as important regulators in various physiological processes in health and disease through their ability to fine-tune cellular responses. Herein, we summarize the versatile roles of miRNAs implicated in diabetic wound healing in key stages including inflammation, angiogenesis, re-epithelialization, and remodeling. Furthermore, we highlight current evidence through which miRNAs exert control of gene expression and signaling pathways in the reparative response that may provide opportunities for therapeutic intervention for this potentially devastating disease state.

The association between MCP-1, VEGF polymorphisms and their serum levels in patients with diabetic foot ulcer

The purpose of the present study was to investigate distribution of monocyte chemoattractant protein-1 (MCP-1) -2518A/G and vascular endothelial growth factor (VEGF) -634G/C polymorphisms in type 2 diabetes melitus patients (T2DM) presenting diabetic foot ulcer (DFU). Additionally, we evaluated the effects of these 2 polymorphisms on serum levels of MCP-1 and VEGF in the study population.Patients diagnosed with T2DM without or with DFU were recruited in the study. The distribution of MCP-1 -2518A/G and VEGF -634G/C polymorphisms was investigated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Enzyme-linked immunosorbent assay (ELISA) was applied to detect the protein levels of MCP-1 and VEGF. The comparisons of protein levels in DFU patients were performed by student t test according to their genotypes.The frequencies of GG genotype and G allele of MCP-1 -2518A/G was increased in DFU patients, compared with T2DM patients (odds ratio [OR] = 2.60, 95% confidence interval [CI] = 1.23-5.50, P = .011 and OR = 1.72, 95% CI = 1.18-2.50, P = .005, respectively). Moreover, the increased frequency of GG was significantly associated with up-regulated MCP-1 level in DFU patients (P < .001). Analysis for VEGF -634G/C polymorphisms indicated that the prevalence of CC genotype and C allele of the polymorphisms was decreased in DFU patients, compared with T2DM patients (OR = 0.36, 95% CI = 0.17-0.77, P = .008 and OR = 0.63, 95% CI = 0.43-0.91, P = .015, respectively). DFU patients carrying CC genotype had a higher level of VEGF than those with other genotypes (P = .007).MCP-1 -2518A/G and VEGF -634G/C polymorphisms may involve in occurrence and progress of DFU through regulating transcription activity of the genes.

Descriptive vs mechanistic scientific approach to study wound healing and its inhibition: Is there a value of translational research involving human subjects?

The clinical field of wound healing is challenged by numerous hurdles. Not only are wound-healing disorders complex and multifactorial, but the corresponding patient population is diverse, often elderly and burdened by multiple comorbidities such as diabetes and cardiovascular disease. The care of such patients requires a dedicated, multidisciplinary team of physicians, surgeons, nurses and scientists. In spite of the critical clinical need, it has been over 15 years since a treatment received approval for efficacy by the FDA in the United States. Among the reasons contributing to this lack of effective new treatment modalities is poor understanding of mechanisms that inhibit healing in patients. Additionally, preclinical models do not fully reflect the disease complexity of the human condition, which brings us to a paradox: if we are to use a "mechanistic" approach that favours animal models, we can dissect specific mechanisms using advanced genetic, molecular and cellular technologies, with the caveat that it may not be directly applicable to patients. Traditionally, scientific review panels, for either grant funding or manuscript publication purposes, favour such "mechanistic" approaches whereby human tissue analyses, deemed "descriptive" science, are characterized as a "fishing expedition" and are considered "fatally flawed." However, more emerging evidence supports the notion that the use of human samples provides significant new knowledge regarding the molecular and cellular mechanisms that control wound healing and contribute to inhibition of the process in patients. Here, we discuss the advances, benefits and challenges of translational research in wound healing focusing on human subject research.

Crosstalk Between the Unfolded Protein Response, MicroRNAs, and Insulin Signaling Pathways: In Search of Biomarkers for the Diagnosis and Treatment of Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is a metabolic disorder that is characterized by functional defects in glucose metabolism and insulin secretion. Its complex etiology and multifaceted nature have made it difficult to design effective therapies for early diagnosis and treatment. Several lines of evidence indicate that aberrant activation of the unfolded protein response (UPR) in response to endoplasmic reticulum (ER) stress impairs the β cell's ability to respond to glucose and promotes apoptosis. Elucidating the molecular mechanisms that govern β cell dysfunction and cell death can help investigators design therapies to halt or prevent the development of T2DM. Early diagnosis of T2DM, however, warrants additionally the identification of potential biomarkers. MicroRNAs (miRNAs) are key regulators of transcriptional processes that modulate various features of insulin signaling, such as insulin sensitivity, glucose tolerance, and insulin secretion. A deeper understanding of how changes in patterns of expression of miRNAs correlate with altered glucose metabolism can enable investigators to develop methods for the early diagnosis and treatment of T2DM. The first part of this review examines how altered expression of specific UPR pathway proteins disrupts ER function and causes β cell dysfunction, while the second part discusses the potential role of miRNAs in the diagnostic and treatment of T2DM.

Skin Wound Healing Is Accelerated by a Lipid Mixture Representing Major Lipid Components of Chamaecyparis obtusa Plant Extract

In chronic nonhealing wounds, the healing process is disrupted and wounds are often infected with bacteria. About 85% of lower extremity amputations in diabetes are attributed to deep infection of foot ulcers. Therefore, infection control is critical for wound care. In this study, we analyzed lipid composition of Chamaecyparis obtusa extract, and we describe the wound-healing properties of its combination of 10 major lipid components. A 10-lipid mixture up-regulated HBD-3 and LL-37 through the olfactory receptor 2AT4 and induced phosphorylation of extracellular signal-regulated kinases and p38 mitogen-activated protein kinases in primary human keratinocytes. In addition, the 10-lipid mixture had direct bactericidal effects against Staphylococcus aureus and Streptococcus pyogenes and protected against staphylococcal α-toxin-induced keratinocyte cell death. In an animal model, the 10-lipid mixture accelerated skin wound healing and was also effective in healing wounds superinfected with S. aureus. We suggest that the 10-lipid mixture, because of its wound-healing and antimicrobial properties, can be beneficial for wound treatment.

Staphylococcus aureus Triggers Induction of miR-15B-5P to Diminish DNA Repair and Deregulate Inflammatory Response in Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are a debilitating complication of diabetes in which bacterial presence, including the frequent colonizer Staphylococcus aureus, contributes to inhibition of healing. MicroRNAs (miRs) play a role in healing and host response to bacterial pathogens. However, the mechanisms by which miR response to cutaneous S. aureus contributes to DFU pathophysiology are unknown. Here, we show that S. aureus inhibits wound closure and induces miR-15b-5p in acute human and porcine wound models and in chronic DFUs. Transcriptome analyses of DFU tissue showed induction of miR-15b-5p to be critical, regulating many cellular processes, including DNA repair and inflammatory response, by suppressing downstream targets IKBKB, WEE1, FGF2, RAD50, MSH2, and KIT. Using a human wound model, we confirmed that S. aureus-triggered miR-15b-5p induction results in suppression of the inflammatory- and DNA repair-related genes IKBKB and WEE1. Inhibition of DNA repair and accumulation of DNA breaks was functionally confirmed by the presence of the pH2AX within colonized DFUs. We conclude that S. aureus induces miR-15b-5p, subsequently repressing DNA repair and inflammatory response, showing a mechanism of inhibition of healing in DFUs previously unreported, to our knowledge. This underscores a previously unknown role of DNA damage repair in the pathophysiology of DFUs colonized with S. aureus.

Measuring the microbiome of chronic wounds with use of a topical antimicrobial dressing - A feasibility study

BACKGROUND

Polymicrobial communities colonize all wounds, and biofilms are hypothesized to be a key link to the chronic state and stalled healing. Molecular methods offer greater insight when studying microbial ecology in chronic wounds, as only a small fraction of wound bacteria are cultured by currently available methods and studies have shown little agreement between culture and molecular based approaches. Some interventions, like dressings with oxidized silver, are reported to help the stalled wounds move to a normal healing trajectory but the underlying mechanisms are difficult to measure. One hypothesis is that the use of topical antimicrobial dressings targets the wound microbiome and reduces bioburden.

OBJECTIVES

Our objective was to determine if culture-independent molecular methods could be used to identify the microbial composition in chronic wounds, and measure the microbiome over time when a topical antimicrobial dressing is used to reduce bioburden.

METHODS

Patients with chronic wounds defined as >6 weeks in duration and not taking systemic antibiotics were recruited to participate. A wound contact layer containing silver oxynitrate was applied immediately after routine sharp debridement material was collected and swabs of the wound bed taken. Next-generation sequencing of the bacterial 16S rRNA gene in each specimen was used to measure the microbiome.

RESULTS

Distinct bacterial communities were observed between swab and debridement samples, highlighting spatial differences and the importance of sampling consistency. The microbial communities appeared to be similar between different diabetes statuses, but different among the three wound categories included.

CONCLUSIONS

Culture-independent methods can be applied to measure the microbiome of chronic wounds even when a topical antimicrobial dressing is applied to the wound.

Topical mevastatin promotes wound healing by inhibiting the transcription factor c-Myc via the glucocorticoid receptor and the long non-coding RNA Gas5

Diabetic foot ulcers (DFUs), a life-threatening complication of diabetes mellitus, have limited treatment options, often resulting in amputations. HMG-CoA reductase inhibitors such as statins are cholesterol-reducing agents that may provide a new therapeutic option. Statins target the cholesterol pathway and block the synthesis of the wound-healing inhibitors farnesyl pyrophosphate (FPP) and cortisol, ligands for the glucocorticoid receptor (GR). Here we demonstrate that the naturally occurring statin mevastatin reverses FPP's effects and promotes healing by using in vitro wound healing assays, human ex vivo and porcine in vivo wound models, and DFU tissue. Moreover, we measured cortisol levels by ELISA and found that mevastatin inhibited cortisol synthesis in keratinocytes and biopsies from patients with DFU. Of note, topical mevastatin stimulated epithelialization and angiogenesis in vivo Mevastatin also reversed FPP-mediated induction of the GR target, the transcription factor c-Myc (a biomarker of non-healing wounds), in porcine and human wound models. Importantly, mevastatin reversed c-Myc overexpression in DFUs. It induced expression of the long noncoding RNA Gas5 that blocks c-Myc expression, which was confirmed by overexpression studies. We conclude that topical mevastatin accelerates wound closure by promoting epithelialization via multiple mechanisms: modulation of GR ligands and induction of the long noncoding RNA Gas5, leading to c-Myc inhibition. In light of these findings, we propose that repurposing statin drugs for topical treatment of DFUs may offer another option for managing this serious condition.

hsa-miR-29c-3p regulates biological function of colorectal cancer by targeting SPARC

Colorectal cancer (CRC) is the most common type of behavioral cancers, miRNAs play a critical role in cancer development and progression. In the present study, we downloaded the original data from Gene Expression Omnibus (GEO) and conduct data analysis. has-mir-29c-3p mimic, inhibitor, negative control or si-SPARC (secreted protein acidic, rich in cysteine) were transfected into HCT116 cells, respectively. Quantitative real time PCR (qRT-PCR) was used to measure has-mir-29c-3p and SPARC mRNA expressions, western blot was used to detect ACAA1 (acetyl-CoA acyltransferase 1), ACOX1 (acyl-CoA oxidase 1), COL1A1(collagen, type I, alpha-1), COL1A2 (collagen, type I, alpha-2), COL4A1 (collagen, type IV, alpha-1), COL5A2 (collagen, type V, alpha-2), COL12A1 (collagen, type XII, alpha-1), CPT2 (carnitine palmitoyltransferase 2), ETHE1 (persulfide dioxygenase), HMGCS2 (3-hydroxy-3-methylglutaryl-CoA synthase 2), SPARC, SQRDL (sulfide quinone oxidoreductase), and TST (thiosulfate sulfurtransferase) protein expression. CCK-8 and wound healing assay were employed to verify cell proliferation and migration. The luciferase reporter assay data made sure the target correlation of has-mir-29c-3p and SPARC. Firstly, we found that the expression of has-mir-29c-3p was lower in CRC tissues than in their paired corresponding non-cancerous tissues and there was significant inversed correlation between has-mir-29c-3p and SPARC. Overexpression of has-mir-29c-3p reduced cell proliferation and migration. SPARC was identified as a direct target of has-mir-29c-3p, whose silencing reduced cell proliferation and migration. These data showed that has-mir-29c-3p regulates CRC cell functions through regulating SPARC expression. Taken together, has-mir-29c-3p may function as an oncogenic miRNA targeting SPARC, targeted modulation of has-mir-29c-3p expression may became a potential strategy for the treatment.

The role of miR-190a-5p contributes to diabetic neuropathic pain via targeting SLC17A6

Introduction

MicroRNAs play a key role in neuropathic pain. In a previous study, miR-190a-5p was significantly downregulated in diabetic neuropathic pain (DNP). However, the role and pathological mechanism of miR-190a-5p in DNP still remain unclear.

Materials and methods

DNP model was established. The paw withdrawal thresholds were measured to assess the mechanical nociceptive response. Dual-luciferase reporter assay was used to confirm the target gene of microRNA. The expressions of microRNA, gene, and protein were detected by the quantitative real-time polymerase chain reaction or Western blot. The levels of IL-1β and IL-6 were detected with the enzyme-linked immuno sorbent assay.

Results

Compared with the control sample, the expression of miR-190a-5p was decreased and SLC17A6 was increased in the spinal tissue from those developing DNP. The bioinformatics and luciferase reporter assay demonstrated that SLC17A6 is a direct target of miR-190a-5p. Up-regulation of miR-190a-5p and inhibition of SLC17A6 could significantly weaken the painful behavior and reduce IL-1β and IL-6 level in DNP.

Conclusion

miR-190a-5p is involved in DNP via targeting SLC17A6, and miR-190a-5p and SLC17A6 may be the therapeutic targets of this disease.

Stress Signals, Mediated by Membranous Glucocorticoid Receptor, Activate PLC/PKC/GSK-3β/β-catenin Pathway to Inhibit Wound Closure

Glucocorticoids (GCs), key mediators of stress signals, are also potent wound healing inhibitors. To understand how stress signals inhibit wound healing, we investigated the role of membranous glucocorticoid receptor (mbGR) by using cell-impermeable BSA-conjugated dexamethasone. We found that mbGR inhibits keratinocyte migration and wound closure by activating a Wnt-like phospholipase (PLC)/ protein kinase C (PKC) signaling cascade. Rapid activation of mbGR/PLC/PKC further leads to activation of known biomarkers of nonhealing found in patients, β-catenin and c-myc. Conversely, a selective inhibitor of PKC, calphostin C, blocks mbGR/PKC pathway, and rescues GC-mediated inhibition of keratinocyte migration in vitro and accelerates wound epithelialization of human wounds ex vivo. This novel signaling mechanism may have a major impact on understanding how stress response via GC signaling regulates homeostasis and its role in development and treatments of skin diseases, including wound healing. To test tissue specificity of this nongenomic signaling mechanism, we tested retinal and bronchial human epithelial cells and fibroblasts. We found that mbGR/PLC/PKC signaling cascade exists in all cell types tested, suggesting a more general role. The discovery of this nongenomic signaling pathway, in which glucocorticoids activate Wnt pathway via mbGR, provides new insights into how stress-mediated signals may activate growth signals in various epithelial and mesenchymal tissues.

Integrative analysis of miRNA and mRNA paired expression profiling of primary fibroblast derived from diabetic foot ulcers reveals multiple impaired cellular functions

Diabetic foot ulcers (DFUs) are one of the major complications of diabetes. Its molecular pathology remains poorly understood, impeding the development of effective treatments. Although it has been established that multiple cell types, including fibroblasts, keratinocytes, macrophages, and endothelial cells, all contribute to inhibition of healing, less is known regarding contributions of individual cell type. Thus, we generated primary fibroblasts from nonhealing DFUs and evaluated their cellular and molecular properties in comparison to nondiabetic foot fibroblasts (NFFs). Specifically, we analyzed both micro-RNA and mRNA expression profiles of primary DFU fibroblasts. Paired genomic analyses identified a total of 331 reciprocal miRNA-mRNA pairs including 21 miRNAs (FC > 2.0) along with 239 predicted target genes (FC > 1.5) that are significantly and differentially expressed. Of these, we focused on three miRNAs (miR-21-5p, miR-34a-5p, miR-145-5p) that were induced in DFU fibroblasts as most differentially regulated. The involvement of these microRNAs in wound healing was investigated by testing the expression of their downstream targets as well as by quantifying cellular behaviors in prospectively collected and generated cell lines from 15 patients (seven DFUF and eight NFF samples). We found large number of downstream targets of miR-21-5p, miR-34a-5p, miR-145-5p to be coordinately regulated in mRNA profiles, which was confirmed by quantitative real-time PCR. Pathway analysis on paired miRNA-mRNA profiles predicted inhibition of cell movement and cell proliferation, as well as activation of cell differentiation and senescence in DFU fibroblasts, which was confirmed by cellular assays. We concluded that induction of miR-21-5p, miR-34a-5p, miR-145-5p in DFU dermal fibroblasts plays an important role in impairing multiple cellular functions, thus contributing to overall inhibition of healing in DFUs.

Function and regulation of microRNA-31 in development and disease

MicroRNAs (miRNAs) are small noncoding RNAs that orchestrate numerous cellular processes both under normal physiological conditions as well as in diseases. This review summarizes the functional roles and transcriptional regulation of the highly evolutionarily conserved miRNA, microRNA-31 (miR-31). miR-31 is an important regulator of embryonic implantation, development, bone and muscle homeostasis, and immune system function. Its own regulation is disrupted during the onset and progression of cancer and autoimmune disorders such as psoriasis and systemic lupus erythematosus. Limited studies suggest that miR-31 is transcriptionally regulated by epigenetics, such as methylation and acetylation, as well as by a number of transcription factors. Overall, miR-31 regulates diverse cellular and developmental processes by targeting genes involved in cell proliferation, apoptosis, cell differentiation, and cell motility. Mol. Reprod. Dev. 83: 654-674, 2016 © 2016 Wiley Periodicals, Inc.