Filaggrin loss-of-function variants are associated with atopic dermatitis phenotypes in a diverse, early-life prospective cohort

Loss-of-function (LoF) variants in the filaggrin (FLG) gene are the strongest known genetic risk factor for atopic dermatitis (AD), but the impact of these variants on AD outcomes is poorly understood. We comprehensively identified genetic variants through targeted region sequencing of FLG in children participating in the Mechanisms of Progression of Atopic Dermatitis to Asthma in Children cohort. Twenty FLG LoF variants were identified, including 1 novel variant and 9 variants not previously associated with AD. FLG LoF variants were found in the cohort. Among these children, the presence of 1 or more FLG LoF variants was associated with moderate/severe AD compared with those with mild AD. Children with FLG LoF variants had a higher SCORing for Atopic Dermatitis (SCORAD) and higher likelihood of food allergy within the first 2.5 years of life. LoF variants were associated with higher transepidermal water loss (TEWL) in both lesional and nonlesional skin. Collectively, our study identifies established and potentially novel AD-associated FLG LoF variants and associates FLG LoF variants with higher TEWL in lesional and nonlesional skin.

Temporal relationships between Staphylococcus aureus colonization, filaggrin expression, and pediatric atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is characterized by Staphylococcus aureus (S. aureus) colonization. Longitudinal early life data delineating relationships of S. aureus colonization, barrier function, and AD outcomes are lacking. We define longitudinal S. aureus endotypes and AD pathogenesis in early life.

METHODS

We defined longitudinal S. aureus skin colonization phenotypes across two annual visits (non-colonized: V1- V2- , early transient: V1+ V2- , late-onset: V1- V2+ , persistent: V1+ V2+ ) in the Mechanisms of Progression of Atopic Dermatitis to Asthma in Children cohort. We analyzed AD severity, sensitization, and skin barrier function across phenotypes, and performed mediation analyses between colonization and FLG expression.

RESULTS

Persistent S. aureus colonization was associated with increased SCORAD at V1 (33.5 vs. 19.0, p = .004) and V2 (40.1 vs.16.9, p < .001), and lower non-lesional (NL) FLG at V2 (1.77 vs. 4.09, p = .029) compared to the non-colonized phenotype, with early transient and late-onset colonization as intermediate phenotypes. Children colonized at V2 demonstrated a decrease in NL-FLG expression from V1 to V2 compared to those non-colonized at V2 (p = .0012), who maintained expression. This effect remained significant even after adjusting for V1 colonization and SCORAD (p = .011).

CONCLUSIONS

Our findings are the first to present longitudinal quantitative FLG expression and S. aureus skin colonization in early life and suggest that a decrease in NL-FLG drives later colonization. Hence, therapies to maintain NL-FLG expression may prevent S. aureus colonization. Further, a longitudinal AD endotype of persistent colonization is characterized by increased AD severity, sensitization, and decreasing NL-FLG.

Heat-killed probiotic Lactobacillus plantarum affects the function of neutrophils but does not improve survival in murine burn injury

Probiotics have become of interest as therapeutics in trauma or sepsis-induced inflammation due to their ability to affects the immune response. However, their use is still under debate due to the potential risk of septicemia. Therefore, heat-killed probiotics offer a potential alternative, with recent research suggesting a comparable immunomodulating potential and increased safety. In a previous study, we demonstrated decreased mortality by administration of live Lactobacillus plantarum in a mouse burn-sepsis model. Neutrophils are an essential innate defense against pathogens. Therefore, our present study aims to understand the impact of heat-killed probiotic L. plantarum (HKLP) on neutrophil function. Utilizing an in vitro stimulation with HKLP and a burn-infection in vivo model, we determined that administration of HKLP induced significant release of granulocyte-colony stimulating factor (G-CSF) and stimulated the release of pro-and anti-inflammatory cytokines. HKLP had no impact on neutrophil function, such as phagocytosis, oxidative burst, and NETosis, but increased apoptosis and activated neutrophils. HKLP did not improve survival. Together, contrary to our hypothesis, heat-killed probiotics did not improve neutrophil function and survival outcome in a murine severe burn injury model.

Biological Targets for Dupuytren Disease

ABSTRACT

Dupuytren disease is a connective tissue disorder occurring on the palm, causing flexion contractures of fingers. There is a pressing need for therapeutic interventions that can slow, stop, or even incrementally reverse the progression of the disease. Numerous in vitro studies have shed light on cellular and molecular agents that contribute to contractures. This article comprehensively reviews various growth factors that can be targeted to prevent and limit the progression and recurrence of Dupuytren contracture (DC). Fibroblasts are the major cell population that has been reported for the contractures in DC, and they are also known to exacerbate the cytokine production. Limiting the fibroblast function by targeting the growth factor production will be of great benefit in treating DC. This review will focus on the studies that have shown to limit the exaggerated function of fibroblasts by reducing the expression of profibrotic growth factors by using antagonizing agents.

The Bactericidal Tandem Drug, AB569: How to Eradicate Antibiotic-Resistant Biofilm Pseudomonas aeruginosa in Multiple Disease Settings Including Cystic Fibrosis, Burns/Wounds and Urinary Tract Infections

The life-threatening pandemic concerning multi-drug resistant (MDR) bacteria is an evolving problem involving increased hospitalizations, billions of dollars in medical costs and a remarkably high number of deaths. Bacterial pathogens have demonstrated the capacity for spontaneous or acquired antibiotic resistance and there is virtually no pool of organisms that have not evolved such potentially clinically catastrophic properties. Although many diseases are linked to such organisms, three include cystic fibrosis (CF), burn/blast wounds and urinary tract infections (UTIs), respectively. Thus, there is a critical need to develop novel, effective antimicrobials for the prevention and treatment of such problematic infections. One of the most formidable, naturally MDR bacterial pathogens is Pseudomonas aeruginosa (PA) that is particularly susceptible to nitric oxide (NO), a component of our innate immune response. This susceptibility sets the translational stage for the use of NO-based therapeutics during the aforementioned human infections. First, we discuss how such NO therapeutics may be able to target problematic infections in each of the aforementioned infectious scenarios. Second, we describe a recent discovery based on years of foundational information, a novel drug known as AB569. AB569 is capable of forming a "time release" of NO from S-nitrosothiols (RSNO). AB569, a bactericidal tandem consisting of acidified NaNO₂ (A-NO₂ ^-) and Na₂-EDTA, is capable of killing all pathogens that are associated with the aforementioned disorders. Third, we described each disease state in brief, the known or predicted effects of AB569 on the viability of PA, its potential toxicity and highly remote possibility for resistance to develop. Finally, we conclude that AB569 can be a viable alternative or addition to conventional antibiotic regimens to treat such highly problematic MDR bacterial infections for civilian and military populations, as well as the economical burden that such organisms pose.

AB569, a non-toxic combination of acidified nitrite and EDTA, is effective at killing the notorious Iraq/Afghanistan combat wound pathogens, multi-drug resistant Acinetobacter baumannii and Acinetobacter spp

Multi-drug resistant (MDR) Acinetobacter baumannii (Ab) and Acinetobacter spp. present monumental global health challenges. These organisms represent model Gram-negative pathogens with known antibiotic resistance and biofilm-forming properties. Herein, a novel, nontoxic biocide, AB569, consisting of acidified nitrite (A-NO₂^-) and ethylenediaminetetraacetic acid (EDTA), demonstrated bactericidal activity against all Ab and Acinetobacter spp. strains, respectively. Average fractional inhibitory concentrations (FICs) of 0.25 mM EDTA plus 4 mM A-NO₂^- were observed across several clinical reference and multiple combat wound isolates from the Iraq/Afghanistan wars. Importantly, toxicity testing on human dermal fibroblasts (HDFa) revealed an upper toxicity limit of 3 mM EDTA plus 64 mM A-NO₂^-, and thus are in the therapeutic range for effective Ab and Acinetobacter spp. treatment. Following treatment of Ab strain ATCC 19606 with AB569, quantitative PCR analysis of selected genes products to be responsive to AB569 revealed up-regulation of iron regulated genes involved in siderophore production, siderophore biosynthesis non-ribosomal peptide synthetase module (SBNRPSM), and siderophore biosynthesis protein monooxygenase (SBPM) when compared to untreated organisms. Taken together, treating Ab infections with AB569 at inhibitory concentrations reveals the potential clinical application of preventing Ab from gaining an early growth advantage during infection followed by extensive bactericidal activity upon subsequent exposures.

Protease levels are significantly altered in pediatric burn wounds

Burn wounds contain high levels of protease activity due to the need to remodel the damaged extracellular matrix proteins. While necessary, excessive protease activity can lead to improper wound healing and is associated with increased contraction and fibrosis. No studies to date have investigated the expression changes of all the collagenases and elastases in burn wounds. The present study compares gene expression changes and changes in collagenase and elastase activity between burn wound eschar and normal skin in a pediatric population. Deidentified pediatric tissues were used for these experiments. Burn wound tissue was excised as part of normal standard care within a week from injury; normal skin was removed during elective plastic surgery procedures. RNA-sequencing was performed and significant results were confirmed with qRT-PCR. Activity assays showed a significant increase in both collagenase and elastase activity in the burn wound tissue compared to the normal skin. Western blotting and substrate zymography of tissue homogenates evaluated the results at the protein levels. Four elastases and three collagenases were determined to be significantly upregulated in the wound tissues by both RNA-sequencing and qRT-PCR. Cathepsin V was the only protease that was significantly downregulated. All but one metalloproteinase studied was significantly upregulated. None of the serine proteases were significantly altered in the wound tissues. In conclusion, matrix metalloproteinases appear to be the most highly elevated proteases after a pediatric burn wound injury, at least within the first 3-7 days. The data warrant further investigation into the effects of MMPs on burn wound healing.

Pirfenidone inhibits epithelial-mesenchymal transition in keloid keratinocytes

Background

Keloids are benign fibroproliferative skin lesions that are difficult to treat and become a lifetime predicament for patients. Several treatment modalities have been put forth, but as yet no satisfactory approach to the prevention or treatment of keloids has been identified. The process of epithelial-to-mesenchymal transition (EMT) has been implicated in keloid scarring, as keloid keratinocytes display an EMT-like phenotype. This study investigated the potential of pirfenidone, an antifibrotic agent, to counteract EMT-like alterations in keloid keratinocytes, including gene expression, cell migratory and proliferative functions.

Methods

Normal and keloid keratinocytes were isolated from discarded normal skin tissues and from resected keloid tissues, respectively. Cells were quiesced for 24 h without epidermal growth factor DS-Qi1MCDigital and were exposed to transforming growth factor-beta1 (TGF-β1; 10 ng/mL), with or without pirfenidone (400 μg/mL), for an additional 24 h. The effects of pirfenidone on cytotoxicity, cell migration, cell proliferation, and on expression of genes and proteins involved in EMT were assayed. Statistical significance was determined by two-way ANOVA using Sigma Plot.

Results

We found that pirfenidone did not elicit any cytotoxic effect at concentrations up to 1000 μg/mL. A statistically significant dose-dependent decrease in basal cell proliferation rate was noted in both normal and keloid keratinocytes when exposed to pirfenidone at concentrations ranging from 200 to 1000 μg/mL. Pirfenidone significantly decreased basal cell migration in both normal and keloid keratinocytes, but a significant decrease in TGF-β1-induced cell migration was seen only in keloid keratinocytes. Significant inhibition of the expression of TGF-β1-induced core EMT genes, namely hyaluronan synthase 2, vimentin, cadherin-11, and wingless-type MMTV integration site family, member 5A along with fibronectin-1, was observed in both normal and keloid keratinocytes treated with pirfenidone. In addition, the protein levels of vimentin and fibronectin were significantly reduced by pirfenidone (400 μg/mL) in both normal and keloid keratinocytes.

Conclusions

For the first time, this study shows the efficacy of pirfenidone in inhibiting the EMT-like phenotype in keratinocytes derived from keloids, suggesting that pirfenidone may counteract a critical contributor of keloid progression and recurrence.

Characterization of Burn Eschar Pericytes

Pericytes are cells that reside adjacent to microvasculature and regulate vascular function. Pericytes gained great interest in the field of wound healing and regenerative medicine due to their multipotential fate and ability to enhance angiogenesis. In burn wounds, scarring and scar contractures are the major pathologic feature and cause loss of mobility. The present study investigated the influence of burn wound environment on pericytes during wound healing. Pericytes isolated from normal skin and tangentially excised burn eschar tissues were analyzed for differences in gene and protein expression using RNA-seq., immunocytochemistry, and ELISA analyses. RNA-seq identified 443 differentially expressed genes between normal- and burn eschar-derived pericytes. Whereas, comparing normal skin pericytes to normal skin fibroblasts identified 1021 distinct genes and comparing burn eschar pericytes to normal skin fibroblasts identified 2449 differential genes. Altogether, forkhead box E1 (FOXE1), a transcription factor, was identified as a unique marker for skin pericytes. Interestingly, FOXE1 levels were significantly elevated in burn eschar pericytes compared to normal. Additionally, burn wound pericytes showed increased expression of profibrotic genes periostin, fibronectin, and endosialin and a gain in contractile function, suggesting a contribution to scarring and fibrosis. Our findings suggest that the burn wound environment promotes pericytes to differentiate into a myofibroblast-like phenotype promoting scar formation and fibrosis.

Investigating the effects of Pirfenidone on TGF-β1 stimulated non-SMAD signaling pathways in Dupuytren's disease -derived fibroblasts

BACKGROUND

Dupuytren's disease (DD) is a progressive, debilitating condition of the hand that can eventually cause contractures of the affected fingers. Transforming growth factor- β1 (TGF-β1) has been reported to play a key role in DD pathology. Increased expression of TGF-β1 has shown to be the main stimulator of myofibroblast activity and in DD contractures. Pirfenidone (PFD), a small active molecule possess the ability to inhibit TGF-β1-mediated action in various fibrotic disorders. Our recent published findings show that PFD reduced TGF-β1-mediated cellular functions implicated in DD through SMAD signaling pathways. In the present study, the effect of PFD on TGF-β1-mediated non-SMAD signaling pathways were investigated in both carpal tunnel (CT) - and DD-derived fibroblasts.

METHODS

Fibroblasts harvested from Dupuytren's disease (DD) and carpal tunnel (CT) tissues were cultured in the presence or absence of TGF-β1 (10 ng/ml) and/or PFD (800 μg/ml). Cell lysates were analyzed using Western blots. Equal amounts of proteins were loaded to determine the phosphorylation levels of phosphatidylinositol-3 kinase (PI3K/AKT), extracellular regulated kinases (ERK1/2), p38 mitogen-activated protein kinase and Rho family related myosin light chain (MLC).

RESULTS

We show that the TGF-β1-induced phosphorylation of AKT was significantly decreased by the addition of PFD (800 μg/mL) in both CT- and DD-derived fibroblasts. Interestingly, there was no significant difference in the phosphorylation levels of both ERK and p38 on TGF-β1- induced cells in both CT-and DD-derived fibroblasts. But, PFD significantly decreased the TGF- β1-induced phosphorylation levels of ERK1/2 in both CT- and DD- cells. In contrast, PFD significantly decreased the basal and TGF- β1-induced phosphorylation levels of p38 in DD-derived fibroblasts. TGF- β1-induced phosphorylation levels of MLC was decreased by PFD in DD-derived fibroblasts.

CONCLUSIONS

These in-vitro results indicate for the first time that PFD has the potential to inhibit TGF-β1-induced non-SMAD signaling pathways in both CT- and DD-derived fibroblasts but pronounced statistically significant inhibition on all molecules was observed only in DD-derived fibroblasts. Our previous studies show that PFD can inhibit TGF-β1- induced SMAD signaling pathway proteins, namely p- SMAD2/SMAD3. These broad and complementary actions suggest PFD as a promising candidate to inhibit the TGF-β1- mediated molecular mechanisms leading to DD fibrosis.

Adipose stem cells enhance excisional wound healing in a porcine model

BACKGROUND

Adipose-derived stem cells (ASCs) are capable of secreting regenerative growth factors and replacing multiple tissue types. Although current literature suggests that ASCs accelerate wound healing and reduce scarring, the dose-response relationship has not been adequately investigated in large animals. We sought to establish a porcine model to optimize dose and delivery.

METHODS

Four-centimeter circular, full thickness excisional wounds were created on the backs of Yorkshire pigs. Fluorescently labeled allogeneic porcine ASCs were injected into the superficial wound bed and around the wound perimeter at high (3.0 × 10⁶ cells/cm²; n = 8), medium (1.0 × 10⁶ cells/cm²; n = 8), and low (0.3 × 10⁶ cells/cm²; n = 8) doses. Control wounds received saline injections (n = 8) or no treatment (n = 8). Dressings were changed twice per week, and wound closure was tracked by surface area tracing. Animals were sacrificed at 1 and 2 wk. Wounds were harvested for real-time quantitative reverse transcriptase polymerase chain reaction, immunohistochemistry, and ASC tracking.

RESULTS

Labeled ASCs integrated into treated wounds by 1 wk in a dose-dependent fashion. Epithelial coverage was achieved by 14 d in all wounds. Wounds receiving high-dose ASCs exhibited thicker granulating neodermis at 7 d and greater wound contraction at 14 d. real-time quantitative reverse transcriptase polymerase chain reaction revealed improved collagen 1:collagen 3 (Col1:Col3) ratio in the medium-dose group and enhanced α-smooth muscle actin in the high-dose group at 14 d. Western blot demonstrated increased cluster of differentiation 31 protein at 2 wk in wounds receiving >10⁶ cells/cm².

CONCLUSIONS

Doses up to 3.0 × 10⁶ cells/cm² were well-tolerated. High-dose ASCs accelerate wound contraction, enhance neovascularization, and may improve scar quality in excisional wounds healing by secondary intention. Doses greater than those previously used may be necessary to achieve desired effects.

Anti-fibrotic action of pirfenidone in Dupuytren's disease-derived fibroblasts

BACKGROUND

Dupuytren's disease (DD) is a complex fibro-proliferative disorder of the hand that is often progressive and eventually can cause contractures of the affected fingers. Transforming growth factor beta (TGF-β1) has been implicated as a key stimulator of myofibroblast activity and fascial contraction in DD. Pirfenidone (PFD) is an active small molecule shown to inhibit TGF-β1-mediated action in other fibrotic disorders. This study investigates the efficacy of PFD in vitro in inhibiting TGF-β1-mediated cellular functions leading to Dupuytren's fibrosis.

METHODS

Fibroblasts harvested from (DD) and carpal tunnel (CT)- tissues were treated with or without TGF-β1 and/or PFD and were subjected to cell migration, cell proliferation and cell contraction assays. ELISA; western blots and real time RT-PCR assays were performed to determine the levels of fibronectin; p-Smad2/Smad3; alpha-smooth muscle actin (α-SMA), α2 chain of type I collagen and α1 chain of type III collagen respectively.

RESULTS

Our results show that PFD effectively inhibits TGF-β1-induced cell migration, proliferation and cell contractile properties of both CT- and DD-derived fibroblasts. TGF-β1-induced α-SMA mRNA and protein levels were inhibited at the higher concentration of PFD (800 μg/ml). Interestingly, TGF-β1 induction of type I and type III collagens and fibronectin was inhibited by PFD in both CT- and DD- derived fibroblasts, but the effect was more prominent in DD cells. PFD down-regulated TGF-β1-induced phosphorylation of Smad2/Smad3, a key factor in the TGF-β1 signaling pathway.

CONCLUSION

Taken together these results suggest the PFD can potentially prevent TGF-β1-induced fibroblast to myofibroblast transformation and inhibit ECM production mainly Type I- and Type III- collagen and fibronectin in DD-derived fibroblasts. Further in-vivo studies with PFD may lead to a novel therapeutic application in preventing the progression or recurrence of Dupuytren's disease.

Local Probiotic Therapy with Lactobacillus plantarum Mitigates Scar Formation in Rabbits after Burn Injury and Infection

BACKGROUND

Infection is the most common complication in burn-injured patients and is believed to contribute to the hypertrophic scarring frequently observed in such injury. Pseudomonas aeruginosa is a common pathogen in burn wound infection. We examined the effect of local probiotic therapy with Lactobacillus plantarum on the severity of the scarring following burn wounding and infection with P. aeruginosa in a rabbit model.

METHODS

Full-thickness burn wounds were inoculated with control vehicle or L. plantarum; wounds were then challenged with bioluminescent P. aeruginosa. The time course of the ensuing infection was monitored by quantification of the emitted light. After allowing wounds to contract to near completion, they were harvested and analyzed for markers of scar formation.

RESULTS

Application of L. plantarum curtailed both the severity and the length of the pseudomonal infection. Probiotic therapy significantly reduced both Type I collagen mRNA concentrations and total collagen protein accumulation in infected wounds, consistent with reduced scarring. Surprisingly, the probiotic showed a nearly equivalent effect in uninfected wounds. Masson's trichrome staining confirmed these findings histologically.

CONCLUSIONS

Lactobacillus plantarum shows exciting potential as a therapeutic agent to both counteract burn wound infection and to alleviate scarring even in the absence of infection.

Local Application of Probiotic Bacteria Prophylaxes against Sepsis and Death Resulting from Burn Wound Infection

Objective

To determine if local prophylactic application of probiotic bacteria to burn wounds will prevent death in a mouse model of burn wound sepsis.

Background

Infection remains the most common complication after burn injury and can result in sepsis and death, despite the use of topical and systemic antibiotics. Pseudomonas aeruginosa is a frequently implicated pathogen. Local application of probiotics directly to burn wounds is an attractive novel intervention that avoids the pitfalls of standard antibiotic therapies.

Methods

A burn-sepsis model was established using a sub-eschar injection of bioluminescent P. aeruginosa; infection was tracked using a charge-coupled camera. Full-thickness burn injuries were placed on the dorsums of adult mice; the injured sites were then treated with vehicle (burn wound control), probiotics (Lactobacillus plantarum only), pathogenic bacteria (Pseudomonas aeruginosa only), or probiotics plus pathogen (Lactobacillus plus Pseudomonas). Animals were monitored until death/moribundity or for one week, then sacrificed. Harvested tissues were subjected to imaging and molecular assays.

Results

Control and probiotic-only animals showed no mortality (100% survival) at one week. Pseudomonas-only animals showed > 90% mortality within 40 hours of infection. In contrast, animals treated with probiotics plus Pseudomonas showed less than 10% mortality. Use of bioluminescent Pseudomonas bacteria demonstrated that probiotic therapy inhibited septicemic accumulation of the pathogen in remote organs. In addition, probiotic therapy successfully suppressed the infection-dependent induction of TNF-α and interleukins 6 and 10 in the liver.

Conclusions

Local probiotic therapy shows great potential as a valuable adjunct in the management of complicated burn injury.

Impact of individualized yoga therapy on perceived quality of life performance on cognitive tasks and depression among Type II diabetic patients

Context:

An individualized approach of providing yoga support can address many of the disease-related concerns indicated in the management of diabetes, specifically the impact on other life activities and long-term functional wellbeing.

Aim:

To analyze the role of regular yoga practice as a self-management approach to achieve glycemic control and psychological wellbeing in Type II diabetic patients.

Methods:

Ninety-one subjects of both sexes responded to the announcement and consented to participate in the study. This was a single group, before and after yoga evaluation without control comparison. The fasting and postprandial blood sugar, glycosylated hemoglobin (HBA1c), cognitive tasks, depression, cognitive failure, and diabetic-related quality of life (QOL) were measured as pretest. The subjects underwent one-to-one individualized yoga therapy sessions, which included 12 supervised sessions spread over a 3-month period. The posttest data were analyzed using paired t-test and Wilcoxon paired rank test.

Results:

Showed significant reduction in fasting blood sugar. QOL of the diabetic patients had improved significantly. There was a significant reduction in the frequency (mean difference of 7.58, P > 0.01) of depressive symptoms and intensity of depression (mean difference 1.66, P > 0.05). Concentration and attention span improved significantly and mean discrepancy score reduced (mean difference 3.42, P > 0.01). There were no marked changes in the postprandial blood sugar and HBA1c.

Conclusion:

Yoga practice enhances the subjective wellbeing, QOL, improves mood and concentration, and facilitates achievement of adequate glycemic control among Type II diabetic patients.

Pericytes: A newly recognized player in wound healing

Pericytes have generally been considered in the context of stabilizing vessels, ensuring the blood barriers, and regulating the flow through capillaries. However, new reports suggest that pericytes may function at critical times to either drive healing with minimal scarring or, perversely, contribute to fibrosis and ongoing scar formation. Beneficially, pericytes probably drive much of the vascular involution that occurs during the transition from the regenerative to the resolution phases of healing. Pathologically, pericytes can assume a fibrotic phenotype and promote scarring. This perspective will discuss pericyte involvement in wound repair and the relationship pericytes form with the parenchymal cells of the skin. We will further evaluate the role pericytes may have in disease progression in relation to chronic wounds and fibrosis.

Imaging the Stromal Vascular Fraction during Soft-Tissue Reconstruction

BACKGROUND

Although fat grafting is an increasingly popular practice, suboptimal volume retention remains an obstacle. Graft enrichment with the stromal vascular fraction has gained attention as a method of increasing graft retention. However, few studies have assessed the fate and impact of transplanted stromal vascular fraction on fat grafts. In vivo imaging techniques can be used to help determine the influence stromal vascular fraction has on transplanted fat.

METHODS

Stromal vascular fraction was labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine iodide (DiR), a near-infrared dye, and tracked in vivo. Proliferation and differentiation of labeled cells were assessed to confirm that labeling did not adversely affect cellular function. Different doses of labeled stromal vascular fraction were tracked within fat grafts over time using the in vivo imaging system.

RESULTS

No significant differences in differentiation and proliferation were observed in labeled versus unlabeled cells (p > 0.05). A pilot study confirmed that stromal vascular fraction fluorescence was localized to fat grafts and different cell doses could be distinguished. A larger-scale in vivo study revealed that stromal vascular fraction fluorescence was statistically significant (p < 0.05) between different cell dose groups and this significance was maintained in higher doses (3 × 10(6) and 2 × 10(6) cells/ml of fat graft) for up to 41 days in vivo.

CONCLUSIONS

DiR labeling allowed the authors to differentiate between cell doses and confirm localization. This article supports the use of DiR labeling in conjunction with in vivo imaging as a tool for imaging stromal vascular fraction within fat grafts.

Chemokines as Therapeutic Targets to Improve Healing Efficiency of Chronic Wounds

Significance: Impaired wound healing leading to chronic wounds is an important clinical problem that needs immediate attention to develop new effective therapies. Members of the chemokine family seem to be attractive and amenable to stimulate the healing process in chronic wounds. Targeting specific chemokines and/or their receptors has the potential to modify chronic inflammation to acute inflammation, which will hasten the healing process. Recent Advances: Over the years, expression levels of various chemokines and their receptors have been identified as key players in the inflammatory phase of wound healing. In addition, they contribute to regulating other phases of wound healing making them key targets for novel therapies. Understanding the signaling pathways of these chemokines will provide valuable clues for modulating their function to enhance the wound healing process. Critical Issues: Inflammation, an important first-stage process in wound healing, is dysregulated in chronic wounds; emerging studies show that chemokines play a crucial role in regulating inflammation. The knowledge gained so far is still limited in understanding the enormous complexity of the chemokine network during inflammation not just in chronic wounds but also in acute (normal) wounds. A much better understanding of the individual chemokines will pave the way for better targets and therapies to improve the healing efficiency of chronic wounds. Future Directions: Effective understanding of the interaction of chemokines and their receptors during chronic wound healing would facilitate the design of novel therapeutic drugs. Development of chemokine-based drugs targeting specific inflammatory cells will be invaluable in the treatment of chronic wounds, in which inflammation plays a major role.

Expression analysis of human adipose-derived stem cells during in vitro differentiation to an adipocyte lineage

Background

Adipose tissue-derived stromal stem cells (ASCs) represent a promising regenerative resource for soft tissue reconstruction. Although autologous grafting of whole fat has long been practiced, a major clinical limitation of this technique is inconsistent long-term graft retention. To understand the changes in cell function during the transition of ASCs into fully mature fat cells, we compared the transcriptome profiles of cultured undifferentiated human primary ASCs under conditions leading to acquisition of a mature adipocyte phenotype.

Methods

Microarray analysis was performed on total RNA extracted from separate ACS isolates of six human adult females before and after 7 days (7 days: early stage) and 21 days (21 days: late stage) of adipocyte differentiation in vitro. Differential gene expression profiles were determined using Partek Genomics Suite Version 6.4 for analysis of variance (ANOVA) based on time in culture. We also performed unsupervised hierarchical clustering to test for gene expression patterns among the three cell populations. Ingenuity Pathway Analysis was used to determine biologically significant networks and canonical pathways relevant to adipogenesis.

Results

Cells at each stage showed remarkable intra-group consistency of expression profiles while abundant differences were detected across stages and groups. More than 14,000 transcripts were significantly altered during differentiation while ~6000 transcripts were affected between 7 days and 21 days cultures. Setting a cutoff of +/-two-fold change, 1350 transcripts were elevated while 2929 genes were significantly decreased by 7 days. Comparison of early and late stage cultures revealed increased expression of 1107 transcripts while 606 genes showed significantly reduced expression. In addition to confirming differential expression of known markers of adipogenesis (e.g., FABP4, ADIPOQ, PLIN4), multiple genes and signaling pathways not previously known to be involved in regulating adipogenesis were identified (e.g. POSTN, PPP1R1A, FGF11) as potential novel mediators of adipogenesis. Quantitative RT-PCR validated the microarray results.

Conclusions

ASC maturation into an adipocyte phenotype proceeds from a gene expression program that involves thousands of genes. This is the first study to compare mRNA expression profiles during early and late stage adipogenesis using cultured human primary ASCs from multiple patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0119-8) contains supplementary material, which is available to authorized users.

Developing an animal model of Dupuytren's disease by orthotopic transplantation of human fibroblasts into athymic rat

Background

Dupuytren’s disease (DD) is a slow, progressive fibroproliferative disorder affecting the palms of the hands. The disease is characterized by the formation of collagen rich- cords which gradually shorten by the action of myofibroblasts resulting in finger contractures. It is a disease that is confined to humans, and a major limiting factor in investigating this disorder has been the lack of a faithful animal model that can recapitulate its distinct biology. The aim of this study was to develop such a model by determining if Dupuytren’s disease (DD)- and control carpal tunnel (CT)-derived fibroblasts could survive in the forepaw of the nude rats and continue to exhibit the distinct characteristics they display in in vitro cultures.

Methods

1x10⁷ fluorescently labeled DD- and CT-derived fibroblasts were transplanted into the left and right forepaws of nude rats respectively. Cells were tracked at regular intervals for a period of two months by quantifying emitted fluorescent signal using an IVIS imaging system. After a period of 62 days rat forepaw connective tissues were harvested for histology and total RNA was isolated. Human-specific probes were used to perform real time RT-PCR assays to examine the expression patterns of gene products associated with fibrosis in DD. Rat forepaw skin was also harvested to serve as an internal control.

Results

Both CT- and DD-derived fibroblasts survived for a period of 62 days, but DD-derived cells showed a significantly greater level of persistent fluorescent signal at the end of this time than did CT-derived cells. mRNA expression levels of α-smooth muscle actin (α-SMA), type I- and type III- collagens were all significantly elevated in the forepaw receiving DD cord-derived fibroblasts in comparison to CT-derived fibroblasts. Masson’s trichrome stain confirmed increased collagen deposition in the forepaw that was injected with DD cord-derived fibroblasts.

Conclusions

For the first time we describe an animal model for Dupuytren’s disease at the orthotopic anatomical location. We further show that gene expression differences between control (CT) and diseased (DD) derived fibroblasts persist when these cells are transplanted to the forepaw of the nude rat. These preliminary findings indicate that, with further refinements, this animal model holds promise as a baseline for investigating novel therapeutic regimens to determine an effective strategy in treating DD.

Increased CCT-eta expression is a marker of latent and active disease and a modulator of fibroblast contractility in Dupuytren's contracture

Dupuytren's contracture (DC) is a fibroproliferative disorder of unknown etiology characterized by a scar-like contracture that develops in the palm and/or digits. We have previously reported that the eta subunit of the chaperonin containing T-complex polypeptide (CCT-eta) is increased in fibrotic wound healing, and is essential for the accumulation of α-smooth muscle actin (α-SMA) in fibroblasts. The purpose of this study was to determine if CCT-eta is similarly implicated in the aberrant fibrosis seen in DC and to investigate the role of CCT-eta in the behavior of myo/fibroblasts in DC. Fibroblasts were obtained from DC-affected palmar fascia, from adjacent phenotypically normal palmar fascia in the same DC patients (PF), and from non-DC palmar fascial tissues in patients undergoing carpal tunnel (CT) release. Inherent contractility in these three populations was examined using fibroblast-populated collagen lattices (FPCLs) and by cell traction force microscopy. Expression of CCT-eta and α-SMA protein was determined by Western blot. The effect of CCT-eta inhibition on the contractility of DC cells was determined by deploying an siRNA versus CCT-eta. DC cells were significantly more contractile than both matching palmar fascial (PF) cells and CT cells in both assays, with PF cells demonstrating an intermediate contractility in the FPCL assay. Whereas α-SMA protein was significantly increased only in DC cells compared to PF and CT cells, CCT-eta protein was significantly increased in both PF and DC cells compared to CT cells. siRNA-mediated depletion of CCT-eta inhibited the accumulation of both CCT-eta and α-SMA protein in DC cells, and also significantly decreased the contractility of treated DC cells. These observations suggest that increased expression of CCT-eta appears to be a marker for latent and active disease in these patients and to be essential for the increased contractility exhibited by these fibroblasts.

Scarless integumentary wound healing in the mammalian fetus: molecular basis and therapeutic implications

Adult mammals respond to injury of their skin/integument by forming scar tissue. Scar is useful in rapidly sealing an injured area, but can also lead to significant morbidity. Mammals in fetal life retain the ability to heal integumentary wounds regeneratively, without scar. The critical molecular mechanisms governing this remarkable phenomenon have been a subject of great interest, in the hopes that these could be dissected and recapitulated in the healing adult wound, with the goal of inducing scarless healing in injured patients. Multiple lines of investigation spanning decades have implicated a number of factors in distinguishing scarless from fibrotic wound healing, including most prominently transforming growth factor-β and interleukin-10, among others. Therapeutic interventions to try to mitigate scarring in adult wounds have been developed out of these studies, and have reached the level of clinical trials in humans, although as yet no FDA-approved treatment exists. More recent expressomic studies have revealed many more genes that are differentially expressed in scarlessly healing fetal wounds compared with adult, and microRNAs have also been identified as participating in the fetal wound healing response. These represent an even greater range of potential therapeutics (or targets for therapy) to translate the promise of scarless fetal wound healing to the injured adult patient.

Fibroblasts from phenotypically normal palmar fascia exhibit molecular profiles highly similar to fibroblasts from active disease in Dupuytren's Contracture

BACKGROUND

Dupuytren's contracture (DC) is a fibroproliferative disorder characterized by the progressive development of a scar-like collagen-rich cord that affects the palmar fascia of the hand and leads to digital flexion contractures. DC is most commonly treated by surgical resection of the diseased tissue, but has a high reported recurrence rate ranging from 27% to 80%. We sought to determine if the transcriptomic profiles of fibroblasts derived from DC-affected palmar fascia, adjacent phenotypically normal palmar fascia, and non-DC palmar fascial tissues might provide mechanistic clues to understanding the puzzle of disease predisposition and recurrence in DC.

METHODS

To achieve this, total RNA was obtained from fibroblasts derived from primary DC-affected palmar fascia, patient-matched unaffected palmar fascia, and palmar fascia from non-DC patients undergoing carpal tunnel release (6 patients in each group). These cells were grown on a type-1 collagen substrate (to better mimic their in vivo environments). Microarray analyses were subsequently performed using Illumina BeadChip arrays to compare the transcriptomic profiles of these three cell populations. Data were analyzed using Significance Analysis of Microarrays (SAM v3.02), hierarchical clustering, concordance mapping and Venn diagram.

RESULTS

We found that the transcriptomic profiles of DC-disease fibroblasts and fibroblasts from unaffected fascia of DC patients exhibited a much greater overlap than fibroblasts derived from the palmar fascia of patients undergoing carpal tunnel release. Quantitative real time RT-PCR confirmed the differential expression of select genes validating the microarray data analyses. These data are consistent with the hypothesis that predisposition and recurrence in DC may stem, at least in part, from intrinsic similarities in the basal gene expression of diseased and phenotypically unaffected palmar fascia fibroblasts. These data also demonstrate that a collagen-rich environment differentially alters gene expression in these cells. In addition, Ingenuity pathway analysis of the specific biological pathways that differentiate DC-derived cells from carpal tunnel-derived cells has identified the potential involvement of microRNAs in this fibroproliferative disorder.

CONCLUSIONS

These data show that the transcriptomic profiles of DC-disease fibroblasts and fibroblasts from unaffected palmar fascia in DC patients are highly similar, and differ significantly from the transcriptomic profiles of fibroblasts from the palmar fascia of patients undergoing carpal tunnel release.

Mechanical effects, antimicrobial efficacy and cytotoxicity of usnic acid as a biofilm prophylaxis in PMMA

Experiments were performed to test the null hypothesis that the addition of a natural occurring antibiotic would not alter mechanical properties of polymethylmethacrylate (PMMA). Compression and four-point bending tests were used to assess mechanical properties of zirconium dioxide bearing bone cement (Type Zr) and barium sulfate bearing bone cement (Type Ba), mixed with the antibiotic usnic acid ("usnic"), used to create a surface resistant to biofilm formation. Addition of usnic had a statistically significant effect on the material properties. Compressive and bending strengths decreased as usnic was added and Type Zr was stronger than Type Ba although material properties remained above recommended minima. With implications of liver toxicity with large doses of usnic taken as a dietary supplement, cytotoxicity tests using bone cement coupons were performed and showed very little or no toxicity in primary cultures of rabbit skin derived fibroblasts. A simple test of usnic's efficacy as a biofilm prophylaxis in PMMA was also conducted. Bone cement coupons with usnic were tested for their effectiveness against methicillin resistant Staphylococcus aureus. Diminished biofilm formation on usnic-containing coupons indicated that usnic can be an effective anti-microbial agent.

Chaperonin containing T-complex polypeptide (CCT) subunit expression in oral mucosal wounds and fibroblasts

Mucosal wound healing in adults has been reported to feature diminished scar formation compared to healing skin wounds. We sought to determine if the expression pattern of chaperonin containing T-complex polypeptide (CCT) subunits in mucosal wounds and fibroblasts is different from that observed in skin wounds and fibroblasts. We found that CCT-beta is the only subunit message to be reduced in wounded mucosa versus unwounded control, and this reduction was confirmed at the protein level. In contrast, mRNA levels of CCT-zeta, -delta, -eta, and -epsilon were significantly increased in mucosal wounds. The increase in CCT-eta was also confirmed at the protein level. Expression levels of CCT-alpha, -beta, -delta; -epsilon, and -theta mRNAs were significantly increased in adult mucosal fibroblasts in culture compared to skin-derived fibroblasts. Western blot analyses confirmed a modest increase in CCT-beta in adult mucosal fibroblasts relative to skin fibroblasts, but CCT-eta protein was unaffected. These differences may contribute to the reported difference in healing outcomes between these two tissue types.

Reversal of TGF-β1 stimulation of α-smooth muscle actin and extracellular matrix components by cyclic AMP in Dupuytren's-derived fibroblasts

BACKGROUND

Myofibroblasts, a derived subset of fibroblasts especially important in scar formation and wound contraction, have been found at elevated levels in affected Dupuytren's tissues. Transformation of fibroblasts to myofibroblasts is characterized by expression of alpha- smooth muscle actin (α-SMA) and increased production of extracellular matrix (ECM) components, both events of relevance to connective tissue remodeling. We propose that increasing the activation of the cyclic AMP (cAMP)/protein kinase A signaling pathway will inhibit transforming growth factor-beta1 (TGF-β1)-induced ECM synthesis and myofibroblast formation and may provide a means to blunt fibrosis.

METHODS

Fibroblasts derived from areas of Dupuytren's contracture cord (DC), from adjacent and phenotypically normal palmar fascia (PF), and from palmar fascia from patients undergoing carpal tunnel release (CTR; CT) were treated with TGF-β1 (2 ng/ml) and/or forskolin (10 μM) (a known stimulator of cAMP). Total RNA and protein extracted was subjected to real time RT-PCR and Western blot analysis.

RESULTS

The basal mRNA expression levels of fibronectin- extra domain A (FN1-EDA), type I (COL1A2) and type III collagen (COL3A1), and connective tissue growth factor (CTGF) were all significantly increased in DC- and in PF-derived cells compared to CT-derived fibroblasts. The TGF-β1 stimulation of α-SMA, CTGF, COL1A2 and COL3A1 was greatly inhibited by concomitant treatment with forskolin, especially in DC-derived cells. In contrast, TGF-β1 stimulation of FN1-EDA showed similar levels of reduction with the addition of forskolin in all three cell types.

CONCLUSION

In sum, increasing cAMP levels show potential to inhibit the formation of myofibroblasts and accumulation of ECM components. Molecular agents that increase cAMP may therefore prove useful in mitigating DC progression or recurrence.

Cloning and expression of rabbit CCT subunits eta and beta in healing cutaneous wounds

We have previously identified the CCT subunit eta as specifically reduced in healing fetal skin wounds by differential display, and observed that this reduction is not seen with any other CCT subunit. We now report the cloning and characterization of the cDNAs for rabbit CCT-eta and its closest evolutionary homolog, CCT-beta. Quantitative examination of CCT-eta and –beta message expression in healing fetal and adult wounds at 12 h post-injury confirms that CCT-eta mRNA is decreased in fetal wound tissues, but actually elevated in adult wound tissues. CCT-beta mRNA, in contrast, remains unchanged in both fetal and adult wound tissues. CCT-eta mRNA remains persistently elevated in healing adult wounds for 28 days following injury, whereas CCT-beta mRNA remains invariant throughout. CCT-eta protein is similarly increased, whereas CCT-beta protein remains unchanged. -smooth muscle actin (-SMA), a recognized substrate of CCT known to be important in integumentary wound healing, was also measured over the course of wound healing, and both mRNA and protein levels were elevated throughout the 28 days.

Multiple displacement amplification as an adjunct to PCR-based detection of Staphylococcus aureus in synovial fluid

Background

Detection of bacterial nucleic acids in synovial fluid following total joint arthroplasty with suspected infection can be difficult; among other technical challenges, inhibitors in the specimens require extensive sample preparation and can diminish assay sensitivity even using polymerase chain reaction (PCR)-based methods. To address this problem a simple protocol for prior use of multiple displacement amplification (MDA) as an adjunct to PCR was established and tested on both purified S. aureus DNA as well as on clinical samples known to contain S. aureus nucleic acids.

Findings

A single round of MDA on purified nucleic acids resulted in a > 300 thousand-fold increase in template DNA on subsequent quantitative PCR (qPCR) analysis. MDA use on clinical samples resulted in at least a 100-fold increase in sensitivity on subsequent qPCR and required no sample preparation other than a simple alkali/heat lysis step. Mixed samples of S. aureus DNA with a 10³ - 10⁴-fold excess of human genomic DNA still allowed for MDA amplification of the minor bacterial component to the threshold of detectability.

Conclusion

MDA is a promising technique that may serve to significantly enhance the sensitivity of molecular assays in cases of suspected joint infection while simultaneously reducing the specimen handling required.

Chaperonin containing T-complex polypeptide subunit eta (CCT-eta) is a specific regulator of fibroblast motility and contractility

Integumentary wounds in mammalian fetuses heal without scar; this scarless wound healing is intrinsic to fetal tissues and is notable for absence of the contraction seen in postnatal (adult) wounds. The precise molecular signals determining the scarless phenotype remain unclear. We have previously reported that the eta subunit of the chaperonin containing T-complex polypeptide (CCT-eta) is specifically reduced in healing fetal wounds in a rabbit model. In this study, we examine the role of CCT-eta in fibroblast motility and contractility, properties essential to wound healing and scar formation. We demonstrate that CCT-eta (but not CCT-beta) is underexpressed in fetal fibroblasts compared to adult fibroblasts. An in vitro wound healing assay demonstrated that adult fibroblasts showed increased cell migration in response to epidermal growth factor (EGF) and platelet derived growth factor (PDGF) stimulation, whereas fetal fibroblasts were unresponsive. Downregulation of CCT-eta in adult fibroblasts with short inhibitory RNA (siRNA) reduced cellular motility, both basal and growth factor-induced; in contrast, siRNA against CCT-beta had no such effect. Adult fibroblasts were more inherently contractile than fetal fibroblasts by cellular traction force microscopy; this contractility was increased by treatment with EGF and PDGF. CCT-eta siRNA inhibited the PDGF-induction of adult fibroblast contractility, whereas CCT-beta siRNA had no such effect. In each of these instances, the effect of downregulating CCT-eta was to modulate the behavior of adult fibroblasts so as to more closely approximate the characteristics of fetal fibroblasts. We next examined the effect of CCT-eta modulation on alpha-smooth muscle actin (alpha-SMA) expression, a gene product well known to play a critical role in adult wound healing. Fetal fibroblasts were found to constitutively express less alpha-SMA than adult cells. Reduction of CCT-eta with siRNA had minimal effect on cellular beta-actin but markedly decreased alpha-SMA; in contrast, reduction of CCT-beta had minimal effect on either actin isoform. Direct inhibition of alpha-SMA with siRNA reduced both basal and growth factor-induced fibroblast motility. These results indicate that CCT-eta is a specific regulator of fibroblast motility and contractility and may be a key determinant of the scarless wound healing phenotype by means of its specific regulation of alpha-SMA expression.

Periostin differentially induces proliferation, contraction and apoptosis of primary Dupuytren's disease and adjacent palmar fascia cells

Dupuytren's disease, (DD), is a fibroproliferative condition of the palmar fascia in the hand, typically resulting in permanent contracture of one or more fingers. This fibromatosis is similar to scarring and other fibroses in displaying excess collagen secretion and contractile myofibroblast differentiation. In this report we expand on previous data demonstrating that POSTN mRNA, which encodes the extra-cellular matrix protein periostin, is up-regulated in Dupuytren's disease cord tissue relative to phenotypically normal palmar fascia. We demonstrate that the protein product of POSTN, periostin, is abundant in Dupuytren's disease cord tissue while little or no periostin immunoreactivity is evident in patient-matched control tissues. The relevance of periostin up-regulation in DD was assessed in primary cultures of cells derived from diseased and phenotypically unaffected palmar fascia from the same patients. These cells were grown in type-1 collagen-enriched culture conditions with or without periostin addition to more closely replicate the in vivo environment. Periostin was found to differentially regulate the apoptosis, proliferation, alpha smooth muscle actin expression and stressed Fibroblast Populated Collagen Lattice contraction of these cell types. We hypothesize that periostin, secreted by disease cord myofibroblasts into the extra-cellular matrix, promotes the transition of resident fibroblasts in the palmar fascia toward a myofibroblast phenotype, thereby promoting disease progression.

Differential expression of chaperonin containing T-complex polypeptide (CCT) subunits during fetal and adult skin wound healing

Integumentary wound healing in early fetal life is regenerative and proceeds without scar formation. Expressomic analysis of this phenomenon by differential display has previously determined that the eta subunit of the cytosolic chaperonin containing T-complex polypeptide (CCT) is downregulated in the healing fetal wound milieu. We now report that no other CCT subunit shares this distinct pattern of gene regulation as determined by limiting dilution reverse transcriptase polymerase chain reaction (RT-PCR); all seven of the remaining CCT subunits demonstrate no change in messenger RNA (mRNA) expression in healing fetal wounds compared to unwounded control tissue. The alpha subunit, however, did evidence reduced message levels in healing adult wound tissue. We herein report on the cloning and sequence of the complementary DNA (cDNA) for rabbit CCT-alpha and confirm its wound specific decrease in adult tissues through quantitative real-time RT-PCR assay. We also confirm that quantitative evaluation of CCT-alpha and CCT-zeta mRNA expression shows no change in healing fetal wounds.

Identification of differentially expressed genes in fibroblasts derived from patients with Dupuytren's Contracture

Dupuytren's contracture (DC) is the most common inherited connective tissue disease of humans and is hypothesized to be associated with aberrant wound healing of the palmar fascia. Fibroblasts and myofibroblasts are believed to play an important role in the genesis of DC and the fibroproliferation and contraction that are hallmarks of this disease. This study compares the gene expression profiles of fibroblasts isolated from DC patients and controls in an attempt to identify key genes whose regulation might be significantly altered in fibroblasts found within the palmar fascia of Dupuytren's patients. Total RNA isolated from diseased palmar fascia (DC) and normal palmar fascia (obtained during carpal tunnel release; 6 samples per group) was subjected to quantitative analyses using two different microarray platforms (GE Code Linktrade mark and Illuminatrade mark) to identify and validate differentially expressed genes. The data obtained was analyzed using The Significance Analysis of Microarrays (SAM) software through which we identified 69 and 40 differentially regulated gene transcripts using the CodeLinktrade mark and Illuminatrade mark platforms, respectively. The CodeLinktrade mark platform identified 18 upregulated and 51 downregulated genes. Using the Illuminatrade mark platform, 40 genes were identified as downregulated, eleven of which were identified by both platforms. Quantitative RT-PCR confirmed the downregulation of three high-interest candidate genes which are all components of the extracellular matrix: proteoglycan 4 (PRG4), fibulin-1 (FBLN-1) transcript variant D, and type XV collagen alpha 1 chain. Overall, our study has identified a variety of candidate genes that may be involved in the pathophysiology of Dupuytren's contracture and may ultimately serve as attractive molecular targets for alternative therapies.

Gene expression patterns in isolated keloid fibroblasts

Keloid scars after skin trauma are a significant clinical problem, especially in black populations, in which the incidence of keloids has been estimated at 4-16%. Keloids are abnormal dermal proliferative scars secondary to dysregulated wound healing. Despite several biochemical studies on the role of extracellular matrix proteins and growth factors during keloid formation, we still do not know what molecules and signals induce this change. Fibroblasts are thought to be the major inductive cell for keloid scar formation. The aim of this study was to identify gene expression patterns that characterize keloid fibroblasts; identifying such genetic disequilibrium may shed light on the molecular signaling events responsible for keloid formation. In this study, we performed gene expression analysis of fibroblasts isolated from keloid lesions from three individuals in comparison with the fibroblasts isolated from normal skin using the Affymetrix U133a chip (22,284 genes and expression sequence tags). We found through J5 test score expression analysis that among 22,284 genes, there were 43 genes that were overexpressed and five genes were underexpressed in keloid fibroblasts when compared with dermal fibroblasts from persons without keloids. The overexpression of three genes not previously reported as being up-regulated in keloids (annexin A2, Transgelin, and RPS18) was confirmed by real-time polymerase chain reaction. Certain overexpressed genes were similar to previous biochemical observations on the protein levels of these overexpressed genes during keloid formation. We also report for the first time that a few tumor-related genes are overexpressed in keloid fibroblasts.

Identification of differentially expressed genes in scarless wound healing utilizing polymerase chain reaction- suppression subtractive hybridization

Wound healing in fetal skin is well known to proceed without scarring, whereas adult (postnatal) skin wound healing is accompanied by scar formation. To identify differentially expressed genes during fetal wound (FW) healing, we have used polymerase chain reaction-suppression subtractive hybridization. This technique allows for a comparative analysis across the entire transcriptome of FW vs. unwounded fetal control tissue, including even potentially novel sequences. Our subtractive hybridization protocol identified 15 clones that are overexpressed in healing FWs, and 20 clones that are underexpressed. These include genes with both known and unknown functions. We have confirmed the differential pattern of expression for four of these candidate genes: elongation factor 1 alpha, elongation initiation factor 4e, and two transcripts thus far known only as an expressed sequence tags. With this approach, we have also identified novel genes potentially involved in scarless wound healing.

Identification of differentially expressed genes in scarless wound healing utilizing polymerase chain reaction-suppression subtractive hybridization

Wound healing in fetal skin is well known to proceed without scarring, whereas adult (postnatal) skin wound healing is accompanied by scar formation. To identify differentially expressed genes during fetal wound (FW) healing, we have used polymerase chain reaction-suppression subtractive hybridization. This technique allows for a comparative analysis across the entire transcriptome of FW vs. unwounded fetal control tissue, including even potentially novel sequences. Our subtractive hybridization protocol identified 15 clones that are overexpressed in healing FWs, and 20 clones that are underexpressed. These include genes with both known and unknown functions. We have confirmed the differential pattern of expression for four of these candidate genes: elongation factor 1 alpha, elongation initiation factor 4e, and two transcripts thus far known only as an expressed sequence tags. With this approach, we have also identified novel genes potentially involved in scarless wound healing.

Interferon-inducible protein 9 (CXCL11)-induced cell motility in keratinocytes requires calcium flux-dependent activation of mu-calpain

Keratinocyte migration is critical to reepithelialization during wound repair. The motility response is promoted by growth factors, cytokines, and cytokines produced in the wound bed, including those that activate the epidermal growth factor (EGF) receptor. The Alu-Leu-Arg-negative CXC chemokine interferon-inducible protein 9 (IP-9; also known as CXCL11, I-TAC, beta-R1, and H-174) is produced by keratinocytes in response to injury. As keratinocytes also express the receptor, CXCR3, this prompted us to examine the role and molecular mechanism by which IP-9 regulates keratinocyte motility. Unexpectedly, as CXCR3 liganding blocks growth factor-induced motility in fibroblasts, IP-9 alone promoted motility in undifferentiated keratinocytes (37 +/- 6% of the level of the highly motogenic EGF) as determined in a two-dimensional in vitro wound healing assay. IP-9 even enhanced EGF-induced motility in undifferentiated keratinocytes (116 +/- 5%; P < 0.05 compared to EGF alone), suggesting two separate mechanisms of action. IP-9-increased motility and -decreased adhesiveness required the intracellular protease calpain. The increases in both motility and calpain activity by IP-9 were blocked by pharmacological and molecular inhibition of phospholipase C-beta3 and chelation of calcium, which prevented an intracellular calcium flux. Molecular downregulation or RNA interference-mediated depletion of mu-calpain (calpain 1) but not M-calpain (calpain 2) blocked IP-9-induced calpain activation and motility. In accord with elimination of IP-9-induced de-adhesion, RNA interference-mediated depletion of calpain 1 but not calpain 2 prevented cleavage of the focal adhesion component focal adhesion kinase and disassembly of vinculin aggregates. In comparison, EGF-induced motility of the same undifferentiated keratinocytes requires the previously described extracellular signal-regulated kinase to the M-calpain pathway. These data demonstrate that while both EGF- and IP-9-induced motility in keratinocytes requires calpain activity, the isoform of calpain triggered depends on the nature of the receptor for the particular ligand. Interestingly, physiological nonapoptotic calcium fluxes were capable of activating mu-calpain, implying that the calcium requirement of mu-calpain for activation is attained during cell signaling. This is also the first demonstration of differential activation of the two ubiquitous calpain isoforms in the same cell by different signals.

Keloid fibroblast responsiveness to epidermal growth factor and activation of downstream intracellular signaling pathways

Keloids, which overgrow the boundaries of the original injury, represent aberrations in the fundamental process of wound healing that include over-abundant cell in-migration, cell proliferation, and inflammation, as well as increased extracellular matrix synthesis and defective remodeling. To understand the key events that result in the formation of these abnormal scars would open new avenues for better understanding of excessive repair, and might provide new therapeutic options. We examined epidermal growth factor receptor (EGFR)-induced cell motility in keloid fibroblasts, as this receptor initiates cell migration during normal wound repair. We show that keloid fibroblasts respond to EGF-induced cell migration but the response is somewhat diminished compared to normal adult fibroblasts (approximately 30% reduced); the mitogenic response was similarly blunted (approximately 5% reduced). Keloid fibroblasts express near normal levels of EGFR (82%), but show a much more attenuated activation of EGFR itself and the motility-associated phospholipase C-gamma. This was reflected in part by rapid loss of EGFR upon exposure to EGF. Interestingly, while extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) activation was relatively robust in keloid fibroblasts, the downstream triggering of the motility-associated calpain activity was blunted. This was reflected by high cell-substratum adhesiveness in the keloid fibroblasts. Thus, the blunted migratory response to EGF noted in keloid fibroblasts appears due to limited activation of two important biochemical switches for cell motility.

Epidermal growth factor activates m-calpain (calpain II), at least in part, by extracellular signal-regulated kinase-mediated phosphorylation

How m-calpain is activated in cells has challenged investigators because in vitro activation requires near-millimolar calcium. Previously, we demonstrated that m-calpain activation by growth factors requires extracellular signal-regulated kinase (ERK); this enables tail deadhesion and allows productive motility. We now show that ERK directly phosphorylates and activates m-calpain both in vitro and in vivo. We identified serine 50 as required for epidermal growth factor (EGF)-induced calpain activation in vitro and in vivo. Replacing the serine with alanine limits activation by EGF and subsequent cell deadhesion and motility. A construct with the serine converted to glutamic acid displays constitutive activity in vivo; expression of an estrogen receptor fusion construct produces a tamoxifen-sensitive enzyme. Interestingly, EGF-induced m-calpain activation occurs in the absence of increased intracellular calcium levels; EGF triggers calpain even in the presence of intracellular calcium chelators and in calcium-free media. These data provide evidence that m-calpain can be activated through the ERK cascade via direct phosphorylation and that this activation may occur in the absence of cytosolic calcium fluxes.

Aging-related attenuation of EGF receptor signaling is mediated in part by increased protein tyrosine phosphatase activity

As fibroblasts near senescence, their responsiveness to external signals diminishes. This well-documented phenomenon likely underlies physiological deterioration and limited tissue regeneration in aging individuals. Understanding the underlying molecular mechanisms would provide opportunities to ameliorate these situations. A key stimulus for human dermal fibroblasts are ligands for the epidermal growth factor receptor (EGFR). We have shown earlier that EGFR expression decreases by about half in near senescent fibroblasts (Shiraha et al., 2000, J. Biol. Chem. 275 (25), 19343-19351). However, as the cell responses are nearly absent near senescence, other aging-related signal attenuation changes must also occur. Herein, we show that EGFR signaling as determined by receptor autophosphorylation is diminished over 80%, with a corresponding decrease in the phosphorylation of the immediate postreceptor adaptor Shc. Interestingly, we found that this was due at least in part to increased dephosphorylation of EGFR. The global cell phosphotyrosine phosphatase activity increased some threefold in near senescent cells. An initial survey of EGFR-associated protein tyrosine phosphatases (PTPases) showed that SHP-1 (PTPIC, HCP, SHPTP-1) and PTPIB levels are increased in parallel in these cells. Concomitantly, we also discovered an increase in expression of receptor protein tyrosine phosphatase alpha (RPTPalpha). Last, inhibition of protein tyrosine phosphatases by sodium orthovanadate in near senescent cells resulted in increased EGFR phosphorylation. These data support a model in which, near senescence, dermal fibroblasts become resistant to EGFR-mediated stimuli by a combination of receptor downregulation and increased signal attenuation.