Endothelial selectins regulate skin wound healing in cooperation with L-selectin and ICAM-1

Misregulation of cell adhesion molecules in the Ciona neural tube closure mutant bugeye

Neural tube closure (NTC) is a complex multi-step morphogenetic process that transforms the flat neural plate found on the surface of the post-gastrulation embryo into the hollow and subsurface central nervous system (CNS). Errors in this process underlie some of the most prevalent human birth defects, and occur in about 1 out of every 1000 births. Previously, we discovered a mutant in the basal chordate Ciona savignyi (named bugeye) that revealed a novel role for a T-Type Calcium Channel (Cav3) in this process. Moreover, the requirement for CAV3s in Xenopus NTC suggests a conserved function among the chordates. Loss of CAV3 leads to defects restricted to anterior NTC, with the brain apparently fully developed, but protruding from the head. Here we report first on a new Cav3 mutant in the related species C. robusta. RNAseq analysis of both C. robusta and C. savignyi bugeye mutants reveals misregulation of a number of transcripts including ones that are involved in cell-cell recognition and adhesion. Two in particular, Selectin and Fibronectin leucine-rich repeat transmembrane, which are aberrantly upregulated in the mutant, are expressed in the closing neural tube, and when disrupted by CRISPR gene editing lead to the open brain phenotype displayed in bugeye mutants. We speculate that these molecules play a transient role in tissue separation and adhesion during NTC and failure to downregulate them leads to an open neural tube.

A Computational Perspective on Molecular Recognition by Galectins

This article presents an overview of recent computational studies dedicated to the analysis of binding between galectins and small-molecule ligands. We first present a summary of the most popular simulation techniques adopted for calculating binding poses and binding energies, and then discuss relevant examples reported in the literature for the three main classes of galectins (dimeric, tandem and chimera). We show that simulation of galectin-ligand interactions is a mature field which has proven invaluable for completing and unraveling experimental observations. Future perspectives to further improve the accuracy and cost-effectiveness of existing computational approaches will involve the development of new schemes to account for solvation and entropy effects, which represent the main current limitations to the accuracy of computational results.

Wound healing: cellular mechanisms and pathological outcomes

Wound healing is a complex, dynamic process supported by a myriad of cellular events that must be tightly coordinated to efficiently repair damaged tissue. Derangement in wound-linked cellular behaviours, as occurs with diabetes and ageing, can lead to healing impairment and the formation of chronic, non-healing wounds. These wounds are a significant socioeconomic burden due to their high prevalence and recurrence. Thus, there is an urgent requirement for the improved biological and clinical understanding of the mechanisms that underpin wound repair. Here, we review the cellular basis of tissue repair and discuss how current and emerging understanding of wound pathology could inform future development of efficacious wound therapies.

A therapeutic oxygen carrier isolated from Arenicola marina decreased P. gingivalis induced inflammation and tissue destruction

The control of inflammation and infection is crucial for periodontal wound healing and regeneration. M101, an oxygen carrier derived from Arenicola marina, was tested for its anti-inflammatory and anti-infectious potential based on its anti-oxidative and tissue oxygenation properties. In vitro, no cytotoxicity was observed in oral epithelial cells (EC) treated with M101. M101 (1 g/L) reduced significantly the gene expression of pro-inflammatory markers such as TNF-α, NF-κΒ and RANKL in P. gingivalis-LPS stimulated and P. gingivalis-infected EC. The proteome array revealed significant down-regulation of pro-inflammatory cytokines (IL-1β and IL-8) and chemokine ligands (RANTES and IP-10), and upregulation of pro-healing mediators (PDGF-BB, TGF-β1, IL-10, IL-2, IL-4, IL-11 and IL-15) and, extracellular and immune modulators (TIMP-2, M-CSF and ICAM-1). M101 significantly increased the gene expression of Resolvin-E1 receptor. Furthermore, M101 treatment reduced P. gingivalis biofilm growth over glass surface, observed with live/dead analysis and by decreased P. gingivalis 16 s rRNA expression (51.7%) (p < 0.05). In mice, M101 reduced the clinical abscess size (50.2%) in P. gingivalis-induced calvarial lesion concomitant with a decreased inflammatory score evaluated through histomorphometric analysis, thus, improving soft tissue and bone healing response. Therefore, M101 may be a novel therapeutic agent that could be beneficial in the management of P. gingivalis associated diseases.

Bioactive borate glass triggers phenotypic changes in adipose stem cells

A bioactive borate glass, 13-93B3 (B3), has been used successfully in the clinic to treat chronic, nonhealing wounds without scarring. However, the mechanism by which B3 stimulates wound healing is poorly understood. Because adipose stem cells (ASCs) have been shown to have multiple roles in wound repair, we hypothesized that B3 triggers ASCs. In this study, we evaluate the effects of B3 on ASC survival, migration, differentiation, and protein secretion in vitro. In concentrations ≤10 mg/ml, B3 did not affect ASC viability under static conditions. B3 promoted the migration of ASCs but did not increase differentiation into bone or fat. B3 also decreased ASCs secretion of collagen I, PAI-1, MCP-1, DR6, DKK-1, angiogenin, IL-1, IGFBP-6, VEGF, and TIMP-2; increased expression of IL-1R and E-selectin; had a transient decrease in IL-6 secretion; and had a transient increase in bFGF secretion. Together, these results show that B3 alters the protein secretion of ASCs.

In vivo migration of Fe3O4@polydopamine nanoparticle-labeled mesenchymal stem cells to burn injury sites and their therapeutic effects in a rat model

Mesenchymal stem cell (MSC)-based therapy has emerged as a promising therapeutic strategy for tissue regeneration and repair. However, efficient targeted delivery to specific tissues remains an open challenge. Here, we non-invasively monitored the migration of MSCs labeled with Fe3O4@polydopamine nanoparticles (Fe3O4@PDA NPs) toward laser burn injury sites in a living rat model and evaluated the effects of the labeled MSCs at the injury site. The Fe3O4@PDA NPs could be effectively incorporated into the MSCs without any negative effects on stem cell properties. Furthermore, they enhanced the migration ability of the MSCs by up-regulating the expression level of C-X-C chemokine receptor type 4 (CXCR4). They also increased the secretion of some cytokines and the expression of healing-related genes in comparison with unlabeled MSCs. Labeled MSCs were intravenously administered into injured rats, and live imaging was performed to monitor MSC migration. Fluorescent signals of the labeled MSCs appeared at burn injury lesions 1 day after injection and then gradually increased up to 7 days. After 7 days, the group injected with the labeled MSCs showed less inflammation compared with those injected with the unlabeled MSCs. Additionally, the labeled MSC group showed increased cytokines and reduced pro-inflammatory factors compared with the unlabeled MSC group. The Fe3O4@PDA NPs enhanced stromal cell-derived factor-1/CXCR4-mediated MSC migration in vivo. Thus, we demonstrated the safety, feasibility, and potential efficacy of using the Fe3O4@PDA NPs for optimizing MSC-based therapeutic strategies for burn wound healing.

Macrophage-Mediated Inflammation in Normal and Diabetic Wound Healing

The healing of cutaneous wounds is dependent on the progression through distinct, yet overlapping phases of wound healing, including hemostasis, inflammation, proliferation, and resolution/remodeling. The failure of these phases to occur in a timely, progressive fashion promotes pathologic wound healing. The macrophage (MΦ) has been demonstrated to play a critical role in the inflammatory phase of tissue repair, where its dynamic plasticity allows this cell to mediate both tissue-destructive and -reparative functions. The ability to understand and control both the initiation and the resolution of inflammation is critical for treating pathologic wound healing. There are now a host of studies demonstrating that metabolic and epigenetic regulation of gene transcription can influence MΦ plasticity in wounds. In this review, we highlight the molecular and epigenetic factors that influence MΦ polarization in both physiologic and pathologic wound healing, with particular attention to diabetic wounds.

The role of photobiomodulation on gene expression of cell adhesion molecules in diabetic wounded fibroblasts in vitro

Cell adhesion molecules (CAMs) are cell surface glycoproteins that facilitate cell-cell contacts and adhesion with the extracellular matrix (ECM). Cellular adhesion is affected by various disease conditions, such as diabetes mellitus (DM) and inflammation. Photobiomodulation (PBM) stimulates biological processes and expression of these cellular molecules. The aim of this experimental work was to demonstrate the role of PBM at 830nm on CAMs in diabetic wounded fibroblast cells. Isolated human skin fibroblast cells were used. Normal (N-) and diabetic wounded (DW-) cells were irradiated with a continuous wave diode laser at 830nm with an energy density of 5J/cm(2). Real time reverse transcriptase polymerase chain reaction (RT-PCR) was used to determine the relative gene expression of 39 CAMs 48h post-irradiation. Normalized expression levels from irradiated cells were calculated relative to non-irradiated control cells according to the 2^(-ΔΔCt) method. Thirty-one genes were significantly regulated in N-cells (28 were genes up-regulated and three genes down-regulated), and 22 genes in DW-cells (five genes were up-regulated and 17 genes down-regulated). PBM induced a stimulatory effect on various CAMs namely cadherins, integrins, selectins and immunoglobulins, and hence may be used as a complementary therapy in advancing treatment of non-healing diabetic ulcers. The regulation of CAMs as well as evaluating the role of PBM on the molecular effects of these genes may expand knowledge and prompt further research into the cellular mechanisms in diabetic wound healing that may lead to valuable clinical outcomes.

An acidic microenvironment sets the humoral pattern recognition molecule PTX3 in a tissue repair mode

Doni et al. use four tissue damage models in mice and find that the fluid phase pattern recognition molecule pentraxin 3 (PTX3) plays a role in tissue remodeling and repair. PTX3 binds fibrinogen/fibrin and plasminogen at an acidic pH within tissues. Mice deficient in PTX3 present defects in fibrin deposition, clot formation, collagen deposition, and macrophage-mediated fibrinolysis.

Pentraxin 3 (PTX3) is a fluid-phase pattern recognition molecule and a key component of the humoral arm of innate immunity. In four different models of tissue damage in mice, PTX3 deficiency was associated with increased fibrin deposition and persistence, and thicker clots, followed by increased collagen deposition, when compared with controls. Ptx3-deficient macrophages showed defective pericellular fibrinolysis in vitro. PTX3-bound fibrinogen/fibrin and plasminogen at acidic pH and increased plasmin-mediated fibrinolysis. The second exon-encoded N-terminal domain of PTX3 recapitulated the activity of the intact molecule. Thus, a prototypic component of humoral innate immunity, PTX3, plays a nonredundant role in the orchestration of tissue repair and remodeling. Tissue acidification resulting from metabolic adaptation during tissue repair sets PTX3 in a tissue remodeling and repair mode, suggesting that matrix and microbial recognition are common, ancestral features of the humoral arm of innate immunity.

Human Wharton's jelly stem cells and its conditioned medium enhance healing of excisional and diabetic wounds

Wound healing is a major problem in diabetic patients and current treatments have met with limited success. We evaluated the treatment of excisional and diabetic wounds using a stem cell isolated from the human umbilical cord Wharton's jelly (hWJSC) that shares unique properties with embryonic and adult mesenchymal stem cells. hWJSCs are non-controversial, available in abundance, hypo-immunogenic, non-tumorigenic, differentiate into keratinocytes, and secrete important molecules for tissue repair. When human skin fibroblasts (CCD) in conventional scratch-wound assays were exposed to hWJSC-conditioned medium (hWJSC-CM) the fibroblasts at the wound edges migrated and completely covered the spaces by day 2 compared to controls. The number of invaded cells, cell viability, total collagen, elastin, and fibronectin levels were significantly greater in the hWJSC-CM treatment arm compared to controls (P < 0.05). When a single application of green fluorescent protein (GFP)-labeled hWJSCs (GFP-hWJSCs) or hWJSC-CM was administered to full-thickness murine excisional and diabetic wounds, healing rates were significantly greater compared to controls (P < 0.05). Wound biopsies collected at various time points showed the presence of green GFP-labeled hWJSCs, positive human keratinocyte markers (cytokeratin, involucrin, filaggrin) and expression of ICAM-1, TIMP-1, and VEGF-A. On histology, the GFP-hWJSCs and hWJSC-CM treated wounds showed reepithelialization, increased vascularity and cellular density and increased sebaceous gland and hair follicle numbers compared to controls. hWJSCs showed increased expression of several miRNAs associated with wound healing compared to CCDs. Our studies demonstrated that hWJSCs enhance healing of excisional and diabetic wounds via differentiation into keratinocytes and release of important molecules.

Vacuum-assisted closure increases ICAM-1, MIF, VEGF and collagen I expression in wound therapy

Severe traumatic wounds are challenging to manage during surgery. The introduction of vacuum-assisted closure (VAC) is a breakthrough in wound management. The aim of the present study was to investigate the effect of VAC on cytokines in wounds during the management of severe traumatic wounds following initial debridement. VAC and conventional wound care (CWC) were independently applied to severe traumatic wounds on pigs. The expression levels of intercellular adhesion molecule-1 (ICAM-1), migration inhibitory factor (MIF), vascular endothelial growth factor (VEGF), basic fibroblast growth factor, collagen I and human fibroblast collagenase 1 were detected by quantitative polymerase chain reaction and western blotting. VAC significantly increased the expression of ICAM-1, MIF, VEGF and collagen I compared with that induced by CWC at the protein and mRNA levels. Therefore, the results of the present study indicate that VAC therapy is an effective method for treating severe traumatic wounds, as it increases the expression of cytokines in wounds. VAC significantly increases the expression of ICAM-1, MIF, VEGF and collagen I to manage severe traumatic wounds.

Choice of anesthetic technique on plasma concentrations of interleukins and cell adhesion molecules

BACKGROUND

Whether inflammatory responses to surgery are comparably activated during total intravenous anesthesia (TIVA) and during volatile anesthesia remains unclear. We thus compared the perioperative effects of TIVA and isoflurane anesthesia on plasma concentrations of proinflammatory and anti-inflammatory interleukins and cell adhesion molecules.

METHODS

Patients having laparoscopic cholecystectomies were randomly allocated to two groups: 44 were assigned to TIVA and 44 to isoflurane anesthesia. IL-1β, IL-6, IL-8, IL-10, IL-13, and the cellular adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were determined preoperatively, before incision, and at 2 and 24 hours postoperatively. Our primary outcomes were area-under-the-curve cytokine and adhesion molecule concentrations over 24 postoperative hours.

RESULTS

The only statistically significant difference in area-under-the-curve concentrations was for IL-6, which was greater in patients given isoflurane:78 (95% confidence interval (CI): 52 to 109) pg/ml versus 33 (22 to 50) pg/ml, P= 0.006. Two hours after surgery, IL-6 was significantly greater than baseline in patients assigned to isoflurane: 47 (95% CI: 4 to 216, P<0.001) pg/ml versus 18 (95%CI: 4 to 374, P<0.001) pg/ml in the TIVA group. In contrast, IL-10 was significantly greater in patients assigned to TIVA: 20 (95% CI: 2 to 140, P<0.001) pg/ml versus 12 (95% CI: 3 to 126, P<0.001) pg/ml. By 24 hours after surgery, concentrations were generally similar between study groups and similar to baseline values.

CONCLUSION

The only biomarker whose postoperative area-under-the-curve concentrations differed significantly as a function of anesthetic management was IL-6. Two hours after surgery, IL-6 concentrations were significantly greater in patients given isoflurane than TIVA. However, the differences were modest and seem unlikely to prove clinically important. Further studies are needed.

Monocytes/macrophages prevent healing defects and left ventricular thrombus formation after myocardial infarction

Myocardial infarction (MI) leads to rapid necrosis of cardiac myocytes. To achieve tissue integrity and function, inflammatory cells are activated, including monocytes/macrophages. However, the effect of monocyte/macrophage recruitment after MI remains poorly defined. After experimental MI, monocytes and macrophages were depleted through serial injections of clodronate-containing liposomes. Monocyte/macrophage infiltration was reduced in the myocardium after MI by active treatment. Mortality was increased due to thromboembolic events in monocyte- and macrophage-depleted animals (92 vs. 33%; P<0.01). Left ventricular thrombi were detectable as early as 24 h after MI; this was reproduced in a genetic model of monocyte/macrophage ablation. A general prothrombotic state, increased infarct expansion, and deficient neovascularization were not observed. Severely compromised extracellular matrix remodeling (collagen I, placebo liposome vs. clodronate liposome, 2.4 ± 0.2 vs. 0.8 ± 0.2 arbitrary units; P<0.001) and locally lost integrity of the endocardium after MI are potential mechanisms. Patients with a left ventricular thrombus had a relative decrease of CD14CD16 monocyte/macrophage subsets in the peripheral blood after MI (no thrombus vs. thrombus, 14.2 ± 0.9 vs. 7.80 ± 0.4%; P<0.05). In summary, monocytes/macrophages are of central importance for healing after MI. Impaired monocyte/macrophage function appears to be an unrecognized new pathophysiological mechanism for left ventricular thrombus development after MI.

The effects of a small dose of dexamethasone on cell adhesion molecules during laparoscopic cholecystectomy

BACKGROUND AND OBJECTIVE

There are only a few publications on the effects of dexamethasone on the plasma levels of cell adhesion molecules (CAMs). The goal of this study was to investigate the effects of dexamethasone 4 mg on the perioperative plasma levels of CAMs (soluble intercellular adhesion molecules [sICAM-1] and soluble vascular cell adhesion molecules [sVCAM-1]) during laparoscopic cholecystectomy.

METHODS

Forty-two patients undergoing laparoscopic cholecystectomy under total intravenous anesthesia were enrolled and randomly divided into two groups: the first group received dexamethasone 4 mg (DEX group, n = 21) and the second group were controls (C group, n = 21). Plasma levels of sICAM-1 and sVCAM-1 were assessed before anesthesia, after induction (before surgery), and at 2 and 24 hours after surgery, respectively. Comparisons were performed for area under the plasma concentration-time curve (AUC) and within-group values.

RESULTS

AUC comparison for sICAM-1 showed significantly increased levels in the C group (p = 0.036), while there was no significant difference for sVCAM-1 (p = 0.052). Within-group analysis showed increased levels for both sICAM-1 and sVCAM-1 in the C group at 24 hours postoperatively (p = 0.35 and p = 0.025, respectively).

CONCLUSIONS

In our study, dexamethasone 4 mg given before laparoscopic cholecystectomy determined a significant decrease in plasma levels of sICAM-1. Both sICAM-1 and sVCAM-1 remained increased compared with baseline at 24 hours in the C group. This may partially explain the postoperative anti-inflammatory effects of dexamethasone. Further studies are needed.

A time-lapse approach to examine chromium and nickel effects on wound healing in vitro

Chromium and nickel cause allergic contact dermatitis, a common biological skin response to sensitizing agents. This study used a conventional in vitro wounding model to study the impact of sensitizing agents on the innate immune response of human keratinocytes. Experiments were designed to evaluate the involvement of specific Toll-like receptors and metalloproteinases as effectors molecules downstream, at a molecular level. Further, keratinocytes were co-cultured with monocytes (THP-1 cells) to reproduce an inductive stimulus on monocytes made by metals. Human keratinocytes (HaCat) were grown on plates covered with collagen type I, chemically treated, and then mechanically injured with a sterile pipette tip. Restoration of the monolayer integrity was monitored by time-lapse video microscopy. Effector gene expression was evaluated by real-time PCR. The presence of chromium significantly dropped the rate of wound closure, while nickel-induced hyper-proliferation ended in an acceleration of the healing process, an event that does not occur in vivo. This latter outcome led to considering nickel as an unsuitable example for use in the experimental model. Focusing solely on the chromium aspect of this study, RNA profiles of selected molecular markers were generated to ascertain if the detrimental stimulus from chromium was eliminated or persisted both in keratinocytes alone and/or during co-cultures of keratinocytes and monocytes. Monocytes accelerated the process of wound repair. This in vitro experimental model highlighted the involvement of innate immunity in response to chromium and might be useful for test molecules of therapeutic interest for the treatment of skin lesions. However, the experience with nickel reveals that there are limitations to the utility of this wound model system after all.

Receptor cleavage and P-selectin-dependent reduction of leukocyte adhesion in the spontaneously hypertensive rat

The SHR, a genetic model for hypertension and the metabolic syndrome, has attenuated leukocyte adhesion to the postcapillary endothelium by an unknown mechanism. Based on recent evidence of elevated levels of MMPs in plasma and on microvascular endothelium of the SHR with cleavage of several receptor types, we hypothesize that the reduced leukocyte-endothelial interaction is a result of enhanced proteolytic cleavage of P-selectin on the postcapillary endothelium and PSGL-1 on leukocytes. The attenuated rolling interactions of SHR leukocytes with the endothelium were restored by chronic treatment with a broad-spectrum MMP inhibitor (CGS) for 24 weeks. The SHR MMP levels, in plasma and mesentery, as well as the systolic blood pressure, decreased significantly with treatment. In the SHR mesentery, labeling of P-selectin in the postcapillary venules by immunohistochemistry demonstrated, on average, a 31% lower extracellular P-selectin density compared with the normotensive WKY. A significantly lower extracellular PSGL-1 density on the membranes of SHR neutrophils compared with the WKY also supported our hypothesis. In vivo stimulation of the mesenteric postcapillary venules with histamine demonstrated that the SHR had an attenuated response, as measured by leukocyte rolling velocity on the endothelium. The reduced P-selectin and PSGL-1 density, on SHR postcapillary endothelium and on SHR leukocytes, respectively, was restored significantly by chronic MMP inhibition. The impaired ability of SHR leukocytes to reduce rolling velocity upon inflammatory stimulation led to fewer firmly adhered leukocytes to the endothelium as a contributor to immune suppression.

Dysregulated selectin expression and monocyte recruitment during ischemia-related vascular remodeling in diabetes mellitus

OBJECTIVE

Diabetes mellitus (DM) is associated with impaired ischemia-related vascular remodeling and also dysregulation of the inflammatory response. We sought to determine whether impaired selectin-mediated monocyte recruitment in ischemic tissues contributes to blunted ischemia-mediated angiogenesis in DM.

METHODS AND RESULTS

Contrast-enhanced ultrasound perfusion imaging and molecular imaging of endothelial P-selectin expression in the proximal hindlimb were performed at 1, 3, and 21 days after arterial ligation in wild-type and db/db mice. Ligation reduced muscle blood flow to ≈0.05 mL/minute per gram in both strains. Significant recovery of flow occurred only in wild-type mice (60%-65% of baseline flow). On molecular imaging, baseline P-selectin signal was 4-fold higher in db/db compared with wild-type mice (P<0.01) but increased minimally at day 1 after ischemia, whereas signal increased approximately 10-fold in wild-type mice (P<0.01). Immunohistology of the hindlimb skeletal muscle demonstrated severely reduced monocyte recruitment in db/db mice compared with wild-type mice. Local treatment with monocyte chemotactic protein-1 corrected the deficits in postischemic P-selectin expression and monocyte recruitment in db/db mice and led to greater recovery in blood flow.

CONCLUSION

In DM, there is dysregulation of the selectin response to limb ischemia, which leads to impaired monocyte recruitment, which may be mechanistically related to reduced vascular remodeling in limb ischemia.

Cytokines, chemokines and growth factors in wound healing

In wound healing, a variety of mediators have been identified throughout the years. The mediators discussed here comprise growth factors, cytokines and chemokines. These mediators act via multiple (specific) receptors to facilitate wound closure. As research in the last years has led to many new findings, there is a need to give an overview on what is known, and on what might possibly play a role as a molecular target for future wound therapy. This review aims to keep the reader up to date with selected important and novel findings regarding growth factors, cytokines and chemokines in wound healing.

The roles of P- and E-selectins and P-selectin glycoprotein ligand-1 in primary and metastatic mouse melanomas

BACKGROUND

Malignant melanoma is often accompanied by a host response of inflammatory cell infiltration that is highly regulated by multiple adhesion molecules.

OBJECTIVE

To evaluate the role of adhesion molecules, including P-selectin glycoprotein ligand-1 (PSGL-1), P-selectin, and E-selectin.

METHODS

Subcutaneous primary growth and metastasis to the lung of B16 melanoma cells were examined in mice lacking PSGL-1, P-selectin, or E-selectin.

RESULTS

Primary subcutaneous growth of B16 melanoma was augmented by loss of PSGL-1, P-selectin, or E-selectin, while pulmonary metastasis was reduced by the loss of E-selectin. The enhancement of subcutaneous tumor growth was associated with a reduced accumulation of natural killer cells, CD4(+) T cells and CD8(+) T cells, while the attenuation of pulmonary metastasis was related to the numbers of CD8(+) T cells. The expressions of transforming growth factor (TGF)-β and interleukin (IL)-6 were correlated with primary subcutaneous growth; TGF-β, IL-6, and interferon-γ were related to number of metastatic lung nodules. Cytotoxicity against melanoma cells in splenocytes and in tumor-draining lymph node cells were not defective by the absence of adhesion molecules, suggesting that the enhancement of tumor growth and metastasis caused by the loss of selectins results from an impaired migration of effector cells into the tissue.

CONCLUSIONS

The results indicate the complexity of anti-tumor responses mediated by adhesion molecules in primary subcutaneous tumors and pulmonary metastasis of murine experimental melanoma.

Effects of streptolysin o on extracellular matrix gene expression in normal human epidermal keratinocytes

ML-05 is a non-hemolytic form of streptolysin O, the membrane-damaging extracellular toxin produced by certain streptococci. ML-05 stimulates keratinocyte migration and proliferation in wound-healing scratch assays and promotes wound healing in a human skin organ culture wound model. Pathway-focused DNA microarrays were used to elucidate ML-05's mechanism of action in wound healing processes. Normal human epidermal keratinocytes (NHEK) were treated with varying concentrations of ML-05 for 24 hours, followed by RNA extraction and cRNA production. Gene expression profiling utilized microarrays containing nucleic acid probes for 113 extracellular matrix (ECM) genes. Microarrays yielded 6 upregulated and 4 downregulated genes with ≥2-fold changes and p<0.05 in t-tests. Quantitative real-time polymerase chain reactions (qPCR) were used to verify gene regulation. Upregulated genes of interest were VCAN (formerly CSPG2, encoding versican), CD44 (encoding hyaluronan receptor), ICAM1 (encoding intercellular adhesion molecule-1) and CTGF (encoding connective tissue growth factor). All four upregulated genes encode proteins involved in promoting keratinocyte migration and proliferation. Downregulated genes of interest were MMP9 (encoding matrix metalloproteinase 9) and SPP1 (encoding osteopontin). ML-05 may enhance wound healing through the expression of specific genes encoding proteins capable of promoting keratinocyte migration, proliferation, and other activities related to maintaining ECM structure and function.

Temporal effects in porcine skin following bromine vapor exposure

Bromine is an industrial chemical that causes severe cutaneous burns. When selecting or developing effective treatments for bromine burns, it is important to understand the molecular mechanisms of tissue damage and wound healing. This study investigated the effect of cutaneous bromine vapor exposure on gene expression using a weanling swine burn model by microarray analysis. Ventral abdominal sites were exposed to a mean calculated bromine vapor concentration of 0.51 g/L for 7 or 17 min. At 6 h, 48 h, and 7 days post-exposure, total RNA from skin samples was isolated, processed, and analyzed with Affymetrix GeneChip® Porcine Genome Arrays (N = 3 per experimental group). Differences in gene expression were observed with respect to exposure duration and sampling time. Ingenuity Pathways Analysis (IPA) revealed four common biological functions (cancer, cellular movement, cell-to-cell signaling and interaction, and tissue development) among the top ten functions of each experimental group, while canonical pathway analysis revealed 9 genes (ARG2, CCR1, HMOX1, ATF2, IL-8, TIMP1, ESR1, HSPAIL, and SELE) that were commonly shared among four significantly altered signaling pathways. Among these, the transcripts encoding HMOX1 and ESR1 were identified using IPA as common potential therapeutic targets for Phase II/III clinical trial or FDA-approved drugs. The present study describes the transcriptional responses to cutaneous bromine vapor exposure identifying molecular networks and genes that could serve as targets for developing therapeutics for bromine-induced skin injury.

Blockade of interaction of alpha9 integrin with its ligands hinders the formation of granulation in cutaneous wound healing

The wound healing is a complex process consisting of inflammatory reaction, proliferation of mesenchymal cells, and formation and contraction of granulation tissue. The integrin receptors have crucial roles in this process. Recently, alpha9 integrin has also been detected on keratinocytes within wound sites. However, its functional significance at various wound healing processes was not fully elucidated. To address the role of alpha9 integrin in wound healing process, we made a full-thickness skin excisional wound and treated mice with anti-alpha9 integrin antibody. It has been shown that wound healing process was divided into three distinct phases: first, the re-epithelialization phase, second, the phase of granulation tissue formation, and finally the phase of contraction of granulation tissue. We found that contraction of granulation tissue was not impaired by blocking the interaction of alpha9 integrin with its ligands, indicating that alpha9 integrin is not involved in myofibroblast differentiation. It is noteworthy that the formation of granulation tissue, as characterized by dense vimentin and CD31-positive area, was impaired. The hindrance of granulation tissue formation is because of the inhibition of adhesion and migration of alpha9 integrin-positive dermal fibroblasts. In conclusion, alpha9 integrin is involved in the formation of granulation tissue through regulating migration and adhesion of dermal fibroblasts in the full-thickness skin excisional wound model.

L-selectin: role in regulating homeostasis and cutaneous inflammation

The maintenance of immune surveillance and the generation of normal immune responses are dependent on leukocyte migration to appropriate lymphoid and non-lymphoid tissues. The process of leukocyte migration occurs through complex and highly regulated interactions between the circulating leukocytes and the vascular endothelium. Multiple families of adhesion molecules as well as specific chemoattractants and their cognate receptors function to stabilize these interactions and induce migration into the tissue. L-selectin is a key adhesion molecule that regulates both the migration of leukocytes at sites of inflammation and the recirculation of lymphocytes between blood and lymphoid tissues. L-selectin-mediated lymphocyte recirculation is required for maintaining the appropriate tissue distribution of lymphocyte subpopulations including naïve and effector subsets such as regulatory T cells. In addition, L-selectin-mediated entry into peripheral lymph nodes is required for optimal induction of lymphocyte homeostatic proliferation during lymphopenia. Importantly, L-selectin has been shown to have both adhesive and signaling functions during leukocyte migration. Specifically, L-selectin is highly efficient at capturing free-flowing leukocytes from the blood and supporting subsequent fast rolling interactions along the vascular endothelium. During rolling, synergistic interactions between L-selectin and integrin functions slow leukocyte rolling velocities allowing for chemoattractant-induced activation and eventual firm adhesion of the leukocyte to the vascular endothelium. Engagement of L-selectin by ligand generates transmembrane signals leading to activation of intracellular signaling pathways, increased integrin binding affinity, and enhanced chemotaxis. L-selectin has also been shown to mediate leukocyte recruitment during chronic inflammatory and autoimmune diseases and thus is a potential therapeutic target for drug development.

Endothelial cells incubated with platelet-rich plasma express PDGF-B and ICAM-1 and induce bone marrow stromal cell migration

Platelet-rich plasma (PRP) is used to accelerate bone repair through the growth factors released by platelets. The purpose of this study was to evaluate if PRP induce human umbilical vein endothelial cells (HUVEC) to express mRNA for osteogenic growth factors and stimulate the migration of bone marrow stromal cell (BMSC). The effects of PRP were compared to those induced by vascular endothelial growth factor-A (VEGF-A) or, as a negative control, by platelet poor plasma (PPP). After incubation with PRP, but not with PPP, HUVEC showed an increased expression of mRNA for platelet derived growth factor-B (PDGF-B), and this effect was not inhibited by an anti-VEGF-A antibody. The migration of BMSC was more stimulated by HUVEC incubated with PRP than by HUVEC incubated with low serum medium or PPP. Besides, PRP increased the expression of intercellular adhesion molecule-1 (ICAM-1) and osteoprotegerin, but did not affect the expression either of the receptor activator for nuclear factor kappaB ligand (RANKL) or of RANK. These findings support the hypothesis that PRP contribute to bone repair by favoring the pro-osteogenic function of endothelial cells, including the recruitment of osteoblast precursors and the expression of adhesion molecules for monocyte/macrophages, while inhibiting their pro-osteolytic properties.

ICAM-1 is necessary for epithelial recruitment of gammadelta T cells and efficient corneal wound healing

Wound healing and inflammation are both significantly reduced in mice that lack gammadelta T cells. Here, the role of epithelial intercellular adhesion molecule-1 (ICAM-1) in gammadelta T cell migration in corneal wound healing was assessed. Wild-type mice had an approximate fivefold increase in epithelial gammadelta T cells at 24 hours after epithelial abrasion. ICAM-1(-/-) mice had 50.9% (P < 0.01) fewer gammadelta T cells resident in unwounded corneal epithelium, which failed to increase in response to epithelial abrasion. Anti-ICAM-1 blocking antibody in wild-type mice reduced epithelial gammadelta T cells to a number comparable to that of ICAM-1(-/-) mice, and mice deficient in lymphocyte function-associated antigen-1 (CD11a/CD18), a principal leukocyte receptor for ICAM-1, exhibited a 48% reduction (P < 0.01) in peak epithelial gammadelta T cells. Re-epithelialization and epithelial cell division were both significantly reduced ( approximately 50% at 18 hours, P < 0.01) after abrasion in ICAM-1(-/-) mice versus wild-type, and at 96 hours, recovery of epithelial thickness was only 66% (P < 0.01) of wild-type. ICAM-1 expression by corneal epithelium in response to epithelial abrasion appears to be critical for accumulation of gammadelta T cells in the epithelium, and deficiency of ICAM-1 significantly delays wound healing. Since gammadelta T cells are necessary for efficient epithelial wound healing, ICAM-1 may contribute to wound healing by facilitating gammadelta T cell migration into the corneal epithelium.

P-selectin glycoprotein ligand-1 contributes to wound healing predominantly as a p-selectin ligand and partly as an e-selectin ligand

Cell adhesion molecules are critical to wound healing through leukocyte recruitment. Although P-selectin glycoprotein ligand-1 (PSGL-1) regulates leukocyte rolling by binding P-selectin, but also binding E- and L-selectins with lower affinity, little is known about a role of PSGL-1 in wound healing. To clarify a role of PSGL-1 and its interaction with E- and P-selectins in wound healing, we investigated cutaneous wound healing in PSGL-1-deficient (PSGL-1(-/-)) mice in comparison with E-selectin(-/-), P-selectin(-/-), and P-selectin(-/-) mice treated with an anti-E-selectin antibody. PSGL-1 deficiency inhibited early wound healing, which was accompanied by decreased inflammatory cell infiltration and growth factor expression. By contrast, E-selectin deficiency did not affect wound healing. In general, the inhibitory effect of PSGL-1 deficiency on wound healing was similar to that of P-selectin deficiency either alone or with E-selectin blockade. However, early granulation tissue formation, late angiogenesis, and early infiltration of neutrophils and macrophages in PSGL-1(-/-) mice were inhibited beyond the inhibition in P-selectin(-/-) mice, but to a similar level of inhibition in P-selectin(-/-) mice with E-selectin blockade. These results suggest that PSGL-1 contributes to wound healing predominantly as a P-selectin ligand and partly as an E-selectin ligand by mediating infiltration of inflammatory cells.

[Electrocardiographic findings during colonoscopy]

Impaired diabetic wound healing constitutes a major health problem. The impaired healing is caused by complex factors such as abnormal keratinocyte and fibroblast migration, proliferation, differentiation, and apoptosis, abnormal macrophage polarization, impaired recruitment of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs), and decreased vascularization. Diabetes-enhanced and prolonged expression of TNF-α also contributes to impaired healing. In this paper, we discuss the abnormal cell responses in diabetic wound healing and the contribution of TNF-α.