Transforming growth factor beta reverses the glucocorticoid-induced wound-healing deficit in rats: possible regulation in macrophages by platelet-derived growth factor

Dendritic epidermal T cell hydrogel induces the polarization of M2 macrophages to promote the healing of deep tissue pressure injury

Dendritic epidermal T cells (DETCs) have been shown to promote wound healing. However, the mechanisms involved need to be better understood. In the present study, we investigated the role and mechanism of DETCs in deep tissue pressure injury (DTPI). We established the DTPI model using C57BL/6 mice. Then, DTPI was evaluated and analyzed by histological staining, immunohistochemistry, real-time PCR, Western blotting, and flow cytometry in different treatment groups (DETCs, DETCs/gel, Matrigel, Saline, and Normal group). The results showed that insulin-like growth factor 1 and vascular endothelial growth factor-A expression increased after local DETCs and DETCs/gel implantation in DTPI on days 3 and 7. M1 (inducible nitric oxide synthas-marked) macrophages were predominant at 3 days after DTPI. At 7 days, M1 macrophages were decreased, and M2 (CD206-marked) macrophages were increased in the DETCs and DETCs/gel groups. In vitro, in the co-culture of DETCs and RAW264.7, CD206 expression was significantly increased in M2 macrophages. In addition, Interleukin-17A initially inhibited wound healing 1 day after injury. However, it promoted wound healing at 7, 14, and 21 days after treatment with DETCs and DETCs/gel, respectively. In conclusion, our data suggest that exogenous DETCs improve DTPI wound healing by regulating M1 to M2 macrophage polarization.

Standardizing urethral stricture models in rats: a comprehensive study on histomorphologic and molecular approach

PURPOSE

To create a reproducible and standardized urethral stricture model in rats, evaluating both histomorphologic findings and gene expression data. In studies involving experimental animals, more standardization is needed for the creation of a urethral stricture model.

METHODS

Sixteen male rats were randomized into two groups. The Sham group (n:8) underwent only a penoscrotal incision, while the stricture group (n:8) had their urethras exposed through a penoscrotal incision, followed by electrocauterization to the corpus spongiosum. On the 15th day, blood and urethral tissues were harvested for histologic and molecular analyses. Histomorphologic, immunohistochemical, and reverse transcription polymerase chain reaction analyses were performed.

RESULTS

The stricture group exhibited more severe and intense spongiofibrosis, inflammation, epithelial desquamation, and congestion in vascular structures compared to the controls (p < 0.05). The urethral tissue in the stricture group showed an increased ratio of inflammation parameters, including Collagen 1A1, Collagen 3A1, elastin, Transforming growth factor β1, α Smooth muscle actin, Platelet-derived growth factor α, and Platelet-derived growth factor β. Transforming growth factor β1, Platelet-derived growth factor α, and Platelet-derived growth factor β each correlated highly with the other six parameters (r > 0.60, p < 0.05).

CONCLUSION

Developing electrocoagulation-induced urethral stricture in rats is a simple, reliable, inexpensive, and reproducible. Reporting histologic data with qualitative and semi-quantitative scoring will enhance data standardization, aiding reader understanding and analysis. Transforming growth factor β and Platelet-derived growth factor play key roles in fibrosis during stricture development. Incorporating these cytokines in urethral stricture animal model studies can demonstrate successful stenosis creation.

Homogeneous preparation of water-soluble products from chitin under alkaline conditions and their cell proliferation in vitro

The purpose of this study was to prepare water-soluble products by homogeneous depolymerization of chitin with H₂O₂ under alkaline conditions and investigate their potential application in wound healing. For the first time, water-soluble products were successfully prepared using a chitin-NaOH/urea solution; the products were chitosans with molecular weights (Mw) of 3.48-33.5 kDa and degrees of deacetylation (DD) > 0.5. Their Mw, DD and yield were affected by the reaction temperature, reaction time, concentration of H₂O₂ and chitin DD. The deacetylation and depolymerization of chitin were achieved simultaneously. The depolymerization of chitin was caused by hydrogen abstraction of HO, whereas the deacetylation resulted from the cleavage of amide bonds by HO^- and HO₂^-, although the latter played a more important role. All water-soluble chitosans markedly promoted the proliferation of human skin fibroblast (HSF) cells, but they inhibited the proliferation of human keratinocyte cells. For the proliferation of HSF, a low concentration of chitosans was important. In addition, water-soluble chitosans with an Mw of 3.48-16.4 kDa markedly stimulated the expression of growth factors such as PDGF and TGF-β by macrophages. Water-soluble chitosans could be used as a potential active component in wound dressings.

Role of TGF-β in Skin Chronic Wounds: A Keratinocyte Perspective

Chronic wounds are characterized for their incapacity to heal within an expected time frame. Potential mechanisms driving this impairment are poorly understood and current hypotheses point to the development of an unbalanced milieu of growth factor and cytokines. Among them, TGF-β is considered to promote the broadest spectrum of effects. Although it is known to contribute to healthy skin homeostasis, the highly context-dependent nature of TGF-β signaling restricts the understanding of its roles in healing and wound chronification. Historically, low TGF-β levels have been suggested as a pattern in chronic wounds. However, a revision of the available evidence in humans indicates that this could constitute a questionable argument. Thus, in chronic wounds, divergences regarding skin tissue compartments seem to be characterized by elevated TGF-β levels only in the epidermis. Understanding how this aspect affects keratinocyte activities and their capacity to re-epithelialize might offer an opportunity to gain comprehensive knowledge of the involvement of TGF-β in chronic wounds. In this review, we compile existing evidence on the roles played by TGF-β during skin wound healing, with special emphasis on keratinocyte responses. Current limitations and future perspectives of TGF-β research in chronic wounds are discussed.

Regenerative potential of platelets in patients with chronic kidney disease

INTRODUCTION

Chronic kidney disease (CKD) is a systemic disease affecting many organs. Progression of renal failure aggravates ongoing inflammation and increases oxidative stress. In the final stage of CKD, it is necessary to use renal replacement therapy. A side effect of dialysis therapy is the synthesis of proinflammatory factors and increased oxidative stress, which activates platelets and immune cells.

AIM OF THE STUDY

To determine the regenerative potential of platelets in patients with CKD based on the analysis of the relationships between substances with potential regenerative action, as well as analysis of the influence of the type of renal replacement therapy used on regeneration of platelets.

MATERIALS AND METHODS

The study group consisted of 117 patients. Based on the type of therapy used, patients were divided into four groups: hemodialysis, peritoneal dialysis, kidney transplant patients, and conservative treatment (30, 30, 27, and 30 patients). The control group consisted of 30 healthy volunteers. The concentrations of IGF-1, TGF-β, and PDGF-B in the blood serum were measured by ELISA methods.

RESULTS

It was shown that renal replacement therapy significantly influences the concentration of platelet growth factors (IGF-1: p = 0.025 and PDGF-B: p = 0.012). There was a relationship between the type of renal replacement therapy and the duration of dialysis, and the concentration of IGF-1, PDGF-B (p < 0.00001, p < 0.001).

CONCLUSIONS

The type of renal replacement therapy has a different effect on the concentration of platelet-derived growth factors IGF-1 and PDGF-B. PD patients had the highest concentrations of all growth factors, and this may be due to the presence of inflammation induced by dialysis-related advanced end-products of glycosylation (AGE).

Tendon healing in the context of complex fractures

Tendons connect muscle to bone and play an integral role in bone and joint alignment and loading. Tendons act as pulleys that provide anchorage of muscle forces for joint motion and stability, as well as for fracture reduction and realignment. Patients that experience complex fractures also have concomitant soft tissue injuries, such as tendon damage or rupture. Tendon injuries that occur at the time of bone fracture have long-term ramifications on musculoskeletal health, yet these injuries are often disregarded in clinical treatment and diagnosis for patients with bone fractures as well as in basic science approaches for understanding bone repair processes. Delayed assessment of soft tissue injuries during evaluation of trauma can lead to chronic pain, dysfunction, and delayed bone healing even following successful fracture repair, highlighting the importance of identifying and treating damaged tendons early. Treatment strategies for bone repair, such as mechanical stabilization and biological therapeutics, can impact tendon healing and function. Because poor tendon healing following complex fracture can significantly impact the function of tendon during bone fracture healing, a need exists to understand the healing process of complex fractures more broadly, beyond the healing of bone. In this review, we explored the mechanical and biological interaction of bone and tendon in the context of complex fracture, as well as the relevance and potential ramifications of tendon damage following bone fracture, which has particular impact on patients that experience complex fractures, such as from combat, automobile accidents, and other trauma.

The effect of Quercus brantii gall extract on burn wound healing in rat

OBJECTIVES

The aim of the present study was to evaluate the effect of Quercus brantii galls extract on the rat skin burn wound healing.

MATERIALS AND METHODS

Ethanol extract of the galls of Q. brantii was used to treat the induced burn wounds on the back of 32 Wistar rats divided into 4 groups. The groups were treated by placebo, 1%, 2% and 4% concentration gall extract gels for 14 days and the efficacy of treatment was assessed based on reduction of burn wound area, as well as histological and molecular characteristics.

RESULTS

The mean wound surface in the 14^th day, in all groups treated by Q. brantii gall extracts were larger than control group and the differences were statistically significant (P=0.043). The mean histological wound healing scores were not statistically different. Analysis of nitric oxide and platelet derived growth factor concentration in wound fluids in the 5^th day of study showed that there was not any significant difference between groups (P=0.468 and 0.312 respectively). Fibroblast growth factor (bFGF) concentration in the wound fluids, was significantly higher in group treated with 1% gall extract gel in comparison to the control group (P=0.026).

CONCLUSION

Our results could not prove the significant positive effect of Q. brantii galls extract on the burning wound healing. More studies with more groups treated with different doses of the Q. brantii extract are recommended.

The mechanism and significance of synergistic induction of the expression of plasminogen activator inhibitor-1 by glucocorticoid and transforming growth factor beta in human ovarian cancer cells

Plasminogen activator inhibitor-1 (PAI-1) plays a key role in tissue remodeling and tumor development by suppression of plasminogen activator function. Glucocorticoids (GCs) and transforming growth factor beta (TGF-β) signal pathways cross-talk to regulate gene expression, but the mechanism is poorly understood. Here we investigated the mechanism and significance of co-regulation of PAI-1 by TGF-β and dexamethasone (DEX), a synthetic glucocorticoid in ovarian cancer cells. We found that TGF-β and DEX showed rapidly synergistic induction of PAI-1 expression, which contributed to the early pro-adhesion effects. The synergistic induction effect was accomplished by several signal pathways, including GC receptor (GR) pathway and TGF-β-activated p38MAPK, ERK and Smad3 pathways. TGF-β-activated p38MAPK and ERK pathways cross-talked with GR pathway to augment the expression of PAI-1 through enhancing DEX-induced GR phosphorylation at Ser211 in ovarian cancer cells. These findings reveal possible novel mechanisms by which TGF-β pathways cooperatively cross-talk with GR pathway to regulate gene expression.

Tamoxifen ameliorates renal tubulointerstitial fibrosis by modulation of estrogen receptor α-mediated transforming growth factor-β1/Smad signaling pathway

BACKGROUND

After insult to the kidney, a renal fibrotic process is initiated with sustained inflammation, fibroblast activation and accumulation of extracellular matrix (ECM). Tamoxifen has been used as an anti-estrogen for the prevention and treatment of breast cancer. In this study, we investigated the protective effects of tamoxifen on unilateral ureteral obstruction (UUO)-induced renal tubulointerstitial fibrosis and its molecular mechanism.

METHODS

Renal fibrosis was induced by UUO in 7-week-old C57BL/6 mice. Tamoxifen (50 mg/kg) was given by oral gavage for 5 days before induction of renal fibrosis. Tamoxifen treatment was continued for 14 days after UUO operation. Histologic changes were examined by periodic acid-Schiff stain and Masson's trichrome stain. Expression of α-smooth muscle actin, vimentin, type I collagen, fibronectin and cell adhesion molecules were evaluated by immunohistochemistry and western blot analysis. We also evaluated the effect of tamoxifen on estrogen receptor (ER)-α-mediated transforming growth factor (TGF)-β1/Smad signaling pathway in vitro.

RESULTS

Renal tubular injury and fibrosis were increased after UUO. Tamoxifen treatment significantly decreased UUO-induced renal tubular injury and fibrosis. Renal fibroblast activation, ECM deposition and inflammation were significantly increased after ureteral ligation. However, tamoxifen treatment significantly decreased UUO-induced renal fibroblast activation, ECM deposition and inflammation by suppression of TGF-β1/Smad signaling pathway in vivo. Tamoxifen decreased TGF-β1-induced fibroblast proliferation and cell migration by modulating ERα-mediated TGF-β1/Smad signaling pathway in vitro.

CONCLUSION

These findings indicate that tamoxifen has a beneficial effect on UUO-induced tubulointerstitial fibrosis by suppression of renal fibroblast activation via modulation of ERα-mediated renal TGF-β1/Smad signaling pathway.

The Role of TGFβ Signaling in Wound Epithelialization

Significance: Transforming growth factor β (TGFβ) has a crucial role in maintaining skin homeostasis. TGFβ signaling is important for re-epithelialization, inflammation, angiogenesis, and granulation tissue formation during wound healing. This review will discuss the most important findings regarding the role of TGFβ in epidermal maintenance and its restoration after injury. Recent Advances: Latest findings on the role of TGFβ signaling in normal and impaired wound healing, including the role of TGFβ pathway in tissue regeneration observed in super-healer animal models, will be reviewed. Critical Issues: The TGFβ pathway is attenuated in nonhealing wounds. Observed suppression of TGFβ signaling in chronic ulcers may contribute to the loss of tissue homeostasis and the inability of keratinocytes to migrate and close a wound. Future Directions: A better understanding of TGFβ signaling may provide new insights not only in the normal epithelialization process, but also in tissue regeneration. Future studies focused on TGFβ-mediated crosstalk between multiple cell types involved in wound healing may lead to development of novel therapeutic advances for chronic wounds.

Pistacia atlantica Resin Has a Dose-Dependent Effect on Angiogenesis and Skin Burn Wound Healing in Rat

Objectives. The aim of the present study was to evaluate the effect of Pistacia atlantica resin extract on the rat skin burn wound healing. Methods. Thirty-two Wistar rats were divided into four groups and treated by vehicle, 5%, 10%, and 20% concentration of Pistacia atlantica resin extract for 14 days (G1, G2, G3, and G4, resp.). The efficacy of treatment was assessed based on reduction of burn wound size and histological and molecular characteristics. Results. α -Pinene (46.57%) was the main content of essential oil of resin. There were no statistically significant differences between groups according to wound size analysis. The mean histological wound healing scores were not statistically different. Capillary counts of G2 and G3 were significantly higher than those of the G1 (P = 0.042 and 0.032, resp.). NO concentration in wound fluids on the 5th day of study was not significantly different between groups (P = 0.468). But bFGF concentration in G2 and G3 and PDGF concentration in G3 were significantly higher in comparison to G1 (P = 0.043, 0.017, and 0.019, resp.). Conclusion. Our results revealed that Pistacia atlantica resin extract has a concentration-dependent effect on the healing of burn wounds after 14 days of treatment by increasing the concentration of bFGF and PDGF and also through improving the angiogenesis.

Alternatives for animal wound model systems

In this chapter a review of animal model systems already being utilized to study normal and pathologic wound healing is provided. We also go into details on alternatives for animal wound model systems. The case is made for limitations in the various approaches. We also discuss the benefits/limitations of in vitro/ex vivo systems bringing everything up to date with our current work on developing a cell-based reporter system for diabetic wound healing.

TGF-β1 expression in wound healing is acutely affected by experimental malnutrition and early enteral feeding

Malnutrition is associated with the delay or failure of healing. We assessed the effect of experimental malnutrition and early enteral feeding with standard diet or diet supplemented with arginine and antioxidants on the levels of mRNA encoding growth factors in acute, open wound healing. Standardised cutaneous dorsal wounds and gastrostomies for enteral feeding were created in malnourished (M, n = 27) and eutrophic control (E, n = 30) Lewis male adult rats. Both M and E rats received isocaloric and isonitrogenous regimens with oral chow and saline (C), standard (S) or supplemented (A) enteral diets. On post-trauma day 7, mRNA levels of growth factor genes were analysed in wound granulation tissue by reverse transcription polymerase chain reaction (RT-PCR). M(C) rats had significantly lower transforming growth factor β(TGF-β1 ) mRNA levels than E(C) rats (2·58 ± 0·83 versus 3·53 ± 0·57, P < 0·01) and in comparison with M(S) and M(A) rats (4·66 ± 2·49 and 4·61 ± 2·11, respectively; P < 0·05). VEGF and KGF-7 mRNA levels were lower in M(A) rats than in E(A) rats (0·74 ± 0·16 versus 1·25 ± 0·66; and 1·07 ± 0·45 versus 1·79 ± 0·89, respectively; P≤ 0·04), but did not differ from levels in E(C) and M(C) animals. In experimental open acute wound healing, previous malnutrition decreased local mRNA levels of TGF-β1 genes, which was minimised by early enteral feeding with standard or supplemented diets.

Transforming growth factor β 1 gene expression during vaginal vs cutaneous surgical woundexpression during vaginal vs cutaneous surgical wound healing in the rabbit

INTRODUCTION AND HYPOTHESIS

Reconstructive pelvic surgery outcome is closely related to the vaginal and pelvic wound healing processes. Transforming growth factor beta 1 (TGF-β1) is a principal mediator of wound repair in dermal tissue. We sought to assess this factor's expression in vaginal and dermal surgical wound repair in the rabbit.

METHODS

We excised bilateral 6-mm full-thickness circular segments from the abdominal skin and vagina in 36 New Zealand White (NZW) nulliparous female rabbits. Animals were sacrificed before, on the day of, and 4, 7, 10, 14, 21, 28, and 35 days after tissue wounding, and their wounds were assessed for surface area and TGF-β1 gene transcription by real-time polymerase chain reaction (PCR).

RESULTS

In both the abdominal skin and vagina, TGF-β1 gene transcription increased immediately after tissue injury, reaching maximal levels on days 4-7, and decreased shortly thereafter, attaining minimal values on day 35. A significant correlation between TGF-β1 expression and the wound's closure rate was found in both tissues.

CONCLUSIONS

TGF-β1 gene transcription significantly correlates with the surgical vaginal and dermal wound closure rate, implying that this factor is involved in the process of wound repair in both tissues.

Tendon healing in vivo: effect of mannose-6-phosphate on flexor tendon adhesion formation

The purpose of this study was to investigate the preventive effect of mannose-6-phosphate on flexor tendon adhesion formation. From a total of 84 adult New Zealand White rabbits, 36 were randomly divided into 2 groups, the normal saline group and the mannose-6-phosphate group, after anastomosis of the flexor tendons. Tendons were harvested at 4 weeks, and biomechanics testing was conducted. The other 48 rabbits were randomly divided into 2 groups, the normal saline group and the mannose-6-phosphate group, after anastomosis of the flexor tendons, and tendons were harvested at 7, 14, 28, and 56 days and analyzed by in situ hybridization to determine the mRNA expression of transforming growth factor (TGF)-β1 and collagen I. The results of biomechanics testing indicated that mannose-6-phosphate can effectively prevent flexor tendon adhesion formation after anastomonsis. The in situ hybridization examination revealed that TGF-β1 and collagen I mRNA expression in the mannose-6-phosphate group was lower than that in the normal saline group at each time point. Mannose-6-phosphate can effectively inhibit the function of TGF-β1 and prevent adhesion formation after flexor tendon injury.

Studies in flexor tendon reconstruction: biomolecular modulation of tendon repair and tissue engineering

The Andrew J. Weiland Medal is presented each year by the American Society for Surgery of the Hand and the American Foundation for Surgery of the Hand for a body of work related to hand surgery research. This essay, awarded the Weiland Medal in 2011, focuses on the clinical need for flexor tendon reconstruction and on investigations into flexor tendon biology. Reconstruction of the upper extremity is limited by 2 major problems after injury or degeneration of the flexor tendons. First, adhesions formed after flexor tendon repair can cause decreased postoperative range of motion and hand function. Second, tendon losses can result from trauma and degenerative diseases, necessitating additional tendon graft material. Tendon adhesions are even more prevalent after tendon grafting; therefore these 2 problems are interrelated and lead to considerable disability. The total costs in terms of disability and inability to return to work are enormous. In this essay, published work from the past 12 years in our basic science laboratory is summarized and presented with the common theme of using molecular techniques to understand the cellular process of flexor tendon wound healing and to create substances and materials to improve tendon repair and regeneration. These are efforts to address 2 interrelated and clinically relevant problems that all hand surgeons face in their practice.

Platelet-rich plasma peptides: key for regeneration

Platelet-derived Growth Factors (GFs) are biologically active peptides that enhance tissue repair mechanisms such as angiogenesis, extracellular matrix remodeling, and cellular effects as stem cells recruitment, chemotaxis, cell proliferation, and differentiation. Platelet-rich plasma (PRP) is used in a variety of clinical applications, based on the premise that higher GF content should promote better healing. Platelet derivatives represent a promising therapeutic modality, offering opportunities for treatment of wounds, ulcers, soft-tissue injuries, and various other applications in cell therapy. PRP can be combined with cell-based therapies such as adipose-derived stem cells, regenerative cell therapy, and transfer factors therapy. This paper describes the biological background of the platelet-derived substances and their potential use in regenerative medicine.

Concise review: bone marrow-derived stem/progenitor cells in cutaneous repair and regeneration

Our understanding of the role of bone marrow (BM)-derived cells in cutaneous homeostasis and wound healing had long been limited to the contribution of inflammatory cells. Recent studies, however, suggest that the BM contributes a significant proportion of noninflammatory cells to the skin, which are present primarily in the dermis in fibroblast-like morphology and in the epidermis in a keratinocyte phenotype; and the number of these BM-derived cells increases markedly after wounding. More recently, several studies indicate that mesenchymal stem cells derived from the BM could significantly impact wound healing in diabetic and nondiabetic animals, through cell differentiation and the release of paracrine factors, implying a profound therapeutic potential. This review discusses the most recent understanding of the contribution of BM-derived noninflammatory cells to cutaneous homeostasis and wound healing.

Glucocorticoid induces mesenchymal-to-epithelial transition and inhibits TGF-β1-induced epithelial-to-mesenchymal transition and cell migration

Epithelial-to-mesenchymal transition (EMT) has been implicated in various physiological and pathological events. In this study, we found that the synthetic glucocorticoid dexamethasone (Dex) can inhibit transforming growth factor-beta1-induced EMT and cell migration. We also demonstrated that Dex inhibits EMT through a mechanism involving the suppression of ROS generation. Surprisingly, Dex alone induced mesenchymal-to-epithelial transition (MET). Dexamethasone treatment abolished Snail1 binding to the E-cadherin promoter, suggesting that suppression of Snail1 contributes to the above roles of Dex. Our findings demonstrate that Dex functions as both a suppressor of EMT and as an inducer of MET and therefore may be implicated in certain pathophysiological events.

Effects of antisense transforming growth factor-beta1 gene transfer on the biological activities of tendon sheath fibroblasts

Recent studies have shown the importance of transforming growth factor-beta (TGF-beta) in flexor tendon wound healing. Decreased adhesion formation and increased range of motion after the administration of TGF-beta antibodies after tendon repair have been shown. But TGF-beta antibodies have a short biologic half-life, and continuous supplementation of exogenous TGF-beta antibodies is not practical. Transfer of growth factor genes to tenocytes provides an alternative to protein therapeutics, and a gene therapy approach will prolong the availability of therapeutic proteins.We investigated the biological activities effects of rabbit tendon sheath fibroblasts transfected by antisense TGF-beta1 gene. Tendon sheath fibroblasts were isolated from New Zealand white rabbits and transfected by antisense TGF-beta1 gene with Lipofectin (Invitrogen, Carlsbad, California). Reverse transcription polymerase chain reaction was used to measure collagen I, collagen III, and TGF-beta1 expression, and Western blot was used to measure collagen protein I expression in tendon sheath fibroblasts after being transfected by antisense TGF-beta1 gene. Reverse transcription polymerase chain reaction displayed that tendon sheath fibroblasts transfected with antisense TGF-beta1 gene showed marked decrease collagen I, collagen III, and TGF-beta1 mRNA expression. Western blot showed that tendon sheath fibroblasts transfected with antisense TGF-beta1 gene showed marked decrease expression of collagen I protein, and there was significant difference compared with the untransfected and empty transfected groups (P<.01). Tendon sheath fibroblasts can transfect with antisense TGF-beta1 gene successfully and can decrease production of collagen I, collagen III, and TGF-beta1, which were factors of tendon adhere formation.

Alternatively activated macrophages elicited by helminth infection can be reprogrammed to enable microbial killing

The prime function of classically activated macrophages (activated by Th1-type signals, such as IFN-gamma) is microbial destruction. Alternatively activated macrophages (activated by Th2 cytokines, such as IL-4 and IL-13) play important roles in allergy and responses to helminth infection. We utilize a murine model of filarial infection, in which adult nematodes are surgically implanted into the peritoneal cavity of mice, as an in vivo source of alternatively activated macrophages. At 3 wk postinfection, the peritoneal exudate cell population is dominated by macrophages, termed nematode-elicited macrophages (NeMphi), that display IL-4-dependent features such as the expression of arginase 1, RELM-alpha (resistin-like molecule alpha), and Ym1. Since increasing evidence suggests that macrophages show functional adaptivity, the response of NeMphi to proinflammatory Th1-activating signals was investigated to determine whether a switch between alternative and classical activation could occur in macrophages differentiated in an in vivo infection setting. Despite the long-term exposure to Th2 cytokines and antiinflammatory signals in vivo, we found that NeMphi were not terminally differentiated but could develop a more classically activated phenotype in response to LPS and IFN-gamma. This was reflected by a switch in the enzymatic pathway for arginine metabolism from arginase to inducible NO synthase and the reduced expression of RELM-alpha and Ym1. Furthermore, this enabled NeMphi to become antimicrobial, as LPS/IFN-gamma-treated NeMphi produced NO that mediated killing of Leishmania mexicana. However, the adaptation to antimicrobial function did not extend to key regulatory pathways, such as IL-12 production, which remained unaltered.

Prevention of adhesions in surgery of the flexor tendons of the hand: what is the evidence?

INTRODUCTION

Despite advances in knowledge and refinements of technique, the management of flexor tendon injuries within the digital sheath continues to present a formidable challenge. This in turn has led to a massive expansion in search of modified surgical therapies and various adjuvant therapies, which could prevent adhesion formation without compromising digital function.

SOURCES OF DATA

A search of PubMed, Medline, CINAHL and Embase databases was performed using the keywords 'tendon adhesion prevention', 'tendon healing', 'adhesion prevention in tendons' and 'adjuvants for adhesion prevention'. Studies detailing the use of surgical, pharmacological and non-pharmacological agents for adhesion prevention in digital flexor tendons were identified, and their bibliographies were thoroughly reviewed to identify further related articles. This search identified 41 studies, which investigated the use of various pharmacological agents in adhesion prevention in digital tendons.

AREAS OF AGREEMENT

There is a need to develop and utilize an optimal method for the prevention of adhesions in the flexor tendons of the hand, due to post-surgical complications.

AREAS OF CONTROVERSY

Even though there have been significant advances in the prevention of adhesions in flexor tendons, it remains to be proved which, if any, of the current methods are the most beneficial.

GROWING POINTS

The only thing that appears clinically justified in adhesion prevention is the need for early post-operative mobilization of digits after tendon injury or repair but the best method of mobilization remains controversial.

AREAS TIMELY FOR DEVELOPING RESEARCH

Suggested changes in surgical techniques and various proposed pharmacological and non-pharmacological modalities need to withstand the test of adequately powered human trials, before their justification for potential benefit in clinical practice is accepted.

Wound healing dressings and drug delivery systems: a review

The variety of wound types has resulted in a wide range of wound dressings with new products frequently introduced to target different aspects of the wound healing process. The ideal dressing should achieve rapid healing at reasonable cost with minimal inconvenience to the patient. This article offers a review of the common wound management dressings and emerging technologies for achieving improved wound healing. It also reviews many of the dressings and novel polymers used for the delivery of drugs to acute, chronic and other types of wound. These include hydrocolloids, alginates, hydrogels, polyurethane, collagen, chitosan, pectin and hyaluronic acid. There is also a brief section on the use of biological polymers as tissue engineered scaffolds and skin grafts. Pharmacological agents such as antibiotics, vitamins, minerals, growth factors and other wound healing accelerators that take active part in the healing process are discussed. Direct delivery of these agents to the wound site is desirable, particularly when systemic delivery could cause organ damage due to toxicological concerns associated with the preferred agents. This review concerns the requirement for formulations with improved properties for effective and accurate delivery of the required therapeutic agents. General formulation approaches towards achieving optimum physical properties and controlled delivery characteristics for an active wound healing dosage form are also considered briefly.

Neuropeptide Y promotes TGF-beta1 production in RAW264.7 cells by activating PI3K pathway via Y1 receptor

OBJECTIVE

To examine the effect of neuropeptide Y (NPY) on TGF-beta1 production in RAW264.7 macrophages.

METHODS

Enzyme linked immunosorbent assay (ELISA) was used to detect TGF-beta1 production. Cell counting kit 8 (CCK-8) was used to assay the viability of RAW264.7 cells. Western blot was used to detect the phosphorylation of PI3K p85.

RESULTS

NPY treatment could promote TGF-beta1 production and rapid phosphorylation of PI3K p85 in RAW264.7 cells via Y1 receptor. The elevated TGF-beta1 production induced by NPY could be abolished by wortmannin pretreatment.

CONCLUSION

NPY may elicit TGF-beta1 production in RAW264.7 cells via Y1 receptor, and the activated PI3K pathway may account for this effect.

Paracrine factors of mesenchymal stem cells recruit macrophages and endothelial lineage cells and enhance wound healing

Bone marrow derived mesenchymal stem cells (BM-MSCs) have been shown to enhance wound healing; however, the mechanisms involved are barely understood. In this study, we examined paracrine factors released by BM-MSCs and their effects on the cells participating in wound healing compared to those released by dermal fibroblasts. Analyses of BM-MSCs with Real-Time PCR and of BM-MSC-conditioned medium by antibody-based protein array and ELISA indicated that BM-MSCs secreted distinctively different cytokines and chemokines, such as greater amounts of VEGF-alpha, IGF-1, EGF, keratinocyte growth factor, angiopoietin-1, stromal derived factor-1, macrophage inflammatory protein-1alpha and beta and erythropoietin, compared to dermal fibroblasts. These molecules are known to be important in normal wound healing. BM-MSC-conditioned medium significantly enhanced migration of macrophages, keratinocytes and endothelial cells and proliferation of keratinocytes and endothelial cells compared to fibroblast-conditioned medium. Moreover, in a mouse model of excisional wound healing, where concentrated BM-MSC-conditioned medium was applied, accelerated wound healing occurred compared to administration of pre-conditioned or fibroblast-conditioned medium. Analysis of cell suspensions derived from the wound by FACS showed that wounds treated with BM-MSC-conditioned medium had increased proportions of CD4/80-positive macrophages and Flk-1-, CD34- or c-kit-positive endothelial (progenitor) cells compared to wounds treated with pre-conditioned medium or fibroblast-conditioned medium. Consistent with the above findings, immunohistochemical analysis of wound sections showed that wounds treated with BM-MSC-conditioned medium had increased abundance of macrophages. Our results suggest that factors released by BM-MSCs recruit macrophages and endothelial lineage cells into the wound thus enhancing wound healing.

Transforming growth factor-beta1-antisense modulates the expression of hepatocyte growth factor/scatter factor in keloid fibroblast cell culture

Abnormal wound healing processes can result in hypertrophic scars and keloids. Transforming growth factor-beta1 (TGF-beta1) and hepatocyte growth factor/scatter factor (HGF/SF) are biphasic growth factor cytokines in physiologic and pathophysiologic conditions. Findings have shown TGF-beta1 to be pivotal in the formation of keloid tissue. Therefore, neutralizing antibodies may allow wound healing without keloid formation. As reported, TGF-beta1 is antagonized by HGF/SF. Some authors have reported that exogenous administration of HGF/SF prevented scar formation. Hence, this study targeted TGF-beta1 and determined the levels of HGF/SF in fibroblast cell culture. Keloid tissue was taken from seven patients. Another seven patients with mature nonhypertrophic scar served as controls. All tissues were cultured, and fibroblast cultures were used for further experiments. The TGF-beta1 antisense was administered at 3 and 6 micromol/ml, and HGF/SF levels were determined after 16, 24, and 48 h of incubation. The levels of HGF/SF showed significant differences after incubation with antisense oligonucleotides. The increasing antisense levels resulted in increased HGF/SF levels (up to 87.66 pg/ml after 48 h of incubation). In conclusion, targeting TGF-beta1 resulted in significantly increased levels of HGF/SF. The clinical relevance could include the use of locally administered HGF/SF in protein or gene form to minimize formation of keloids. Nevertheless, wound healing is the result of many interacting cytokines, so neutralizing or targeting one protein could result in no significant effect.

Annexin-1 modulates repair of gastric mucosal injury

Annexin-1 is a glucocorticoid-inducible protein that plays an important effector role in the resolution of inflammation and has recently been shown to contribute to the resistance of the stomach to injury. Using an integrated genetic and pharmacological approach, we have tested the hypothesis that annexin-1 contributes to the healing of mucosal injury, given that such injury is accompanied by an inflammatory response, which is often associated with an overexpression of annexin-1 expression. Gastric ulcers were induced in mice through serosal application of acetic acid. Annexin-1 expression during the healing of the ulcers was examined. The effects on gastric ulcer healing of treatment with an annexin-1 mimetic (Ac2-26), an antagonist of the annexin-1 receptor (Boc2), or a glucocorticoid (dexamethasone) were examined. Finally, susceptibility to and healing of indomethacin-induced gastric lesions were compared in wild-type and annexin-1-deficient mice. Expression of annexin-1 was significantly increased in the gastric ulcer margin throughout the healing process. Treatment with an annexin-1 mimetic (Ac2-26) significantly enhanced gastric ulcer healing. In contrast, both dexamethasone and an formyl peptide receptor-like-1 (FPRL-1) antagonist impaired the early phase of ulcer healing. Annexin-1-deficient mice exhibited the same susceptibility as wild-type mice to indomethacin-induced gastric damage, but the healing of that damage was impaired in the former. These data support the hypothesis that annexin-1 contributes significantly to the process of healing of gastric mucosal damage.

Immediate mineralocorticoid receptor blockade improves myocardial infarct healing by modulation of the inflammatory response

Mineralocorticoid receptor (MR) blockade reduces morbidity and mortality after acute myocardial infarction; however, the underlying mechanisms are still under investigation. This study examined whether MR antagonism promotes healing of the infarcted myocardium. Starting immediately after coronary ligation, male Wistar rats were treated with the selective MR antagonist eplerenone (100 mg/kg per day by gavage) or placebo for 2 to 7 days. At 7 days, eplerenone therapy versus placebo significantly reduced thinning and dilatation of the infarcted wall, improved left ventricular function, and enhanced neovessel formation in the injured myocardium. At 2 days, eplerenone-treated rats displayed lower plasma corticosterone levels, higher circulating blood monocytes, and more macrophages infiltrating the infarcted myocardium. MR blockade led to a transient upregulation (at days 2 and 3 but not at day 7) of monocyte chemoattractant protein-1, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, interleukin-10, and interleukin-4 and an increase in factor XIIIa protein expression in the healing myocardium. Prevention of macrophage accumulation into the infarct zone by treatment with liposome-encapsulated clodronate almost abrogated the protein expression of factor XIIIa and the beneficial effects of eplerenone on infarct expansion. In conclusion, selective MR blockade immediately after myocardial infarction accelerated macrophage infiltration and transiently increased the expression of healing promoting cytokines and factor XIIIa in the injured myocardium resulting in enhanced infarct neovascularization and reduced early LV dilation and dysfunction.

Hyperbaric oxygen therapy mediates increased nitric oxide production associated with wound healing: a preliminary study

OBJECTIVE

The objective of this preliminary study was to document general somatic and wound nitric oxide (NO) levels during and after hyperbaric oxygen therapy (HBOT).

DESIGN

The study evaluated 6 chronic wound patients that responded favorably to HBOT treatment (20 treatments; 2.0 atmosphere absolute [ATA] x 90 minutes). Successful HBOT was associated with increased wound granulation tissue formation and significantly improved wound closure. Wound fluid and fasting plasma samples were obtained for measurement of nitrate and nitrite (NOx), the stable oxidation products of NO; plasma L-arginine (L-Arg); and asymmetric dimethylarginine (ADMA). NOx measurements were obtained before treatment (baseline), after 10 and 20 treatments, and at 1 and 4 weeks after therapy.

RESULTS

Wound fluid NOx levels tended to increase during treatments, were significantly elevated at 1 and 4 weeks after therapy, and correlated with reductions in wound area. Plasma L-Arg and ADMA were unchanged during and after HBOT.

CONCLUSION

This preliminary study documents a significant increase in local wound NO levels (by NOx measurements) after successful HBOT and suggests that this mechanism may be an important factor in promoting enhanced wound healing and wound closure associated with this therapy.

TGF-beta and wound healing

Wound healing comprises an ordered sequence of events including cell migration and proliferation, synthesis of extracellular matrix, angiogenesis and remodelling. TGF-beta regulates many of these processes. Animal models are used to study healing of simple linear incision wounds and deeper dermal wounds under normal and impaired conditions. TGF-beta increases the rate of healing and the breaking strength of the repaired tissue. It also enhances angiogenesis and consequent blood flow to dermal wounds, partly by stimulating the local release of other growth factors. TGF-beta reverses the adverse affects of glucocorticoids on wound healing and thus may be useful in the treatment of chronic ulcers or wounds in patients whose normal responses have been impaired by therapy with steroids, radiation or other drugs.

Efeitos do uso crônico da dexametasona na cicatrização de feridas cutâneas em ratos

FUNDAMENTOS: Acredita-se que os glicocorticóides prejudiquem a cicatrização, causando decréscimo da proliferação celular, da neovascularização e da produção de matriz. OBJETIVO: Investigar os efeitos do uso crônico dos corticoesteróides na cicatrização de feridas cutâneas. MÉTODOS: Após injeções de dexametasona (0,1mg/kg/dia) por 30 dias, fez-se incisão no dorso de ratos e estudou-se a cicatrização no terceiro, sétimo e 14o dias. A resistência da cicatriz, a densidade do colágeno e a reação inflamatória foram avaliadas pela histometria. RESULTADOS: As cicatrizes do grupo tratado com dexametasona eram menos resistentes à tração em todos os tempos (p=0,008) e apresentavam menor densidade de colágeno. A do colágeno tipo III foi menor em todos os tempos estudados (p<0,0001), e a do colágeno tipo I foi menor apenas no 14º dia (p<0,0001). A infiltração de células inflamatórias foi menor no grupo tratado com dexametasona nas duas primeiras avaliações (p=0,001 e p=0,016), não sendo significativa a diferença no 14º dia (p=0,367). CONCLUSÕES: Verificou-se diminuição da resistência da cicatriz e baixa densidade do colágeno total em todos os tempos estudados. No início do processo observou-se baixa densidade do colágeno tipo III e mais tarde também baixa densidade do colágeno tipo I. Nos tempos iniciais houve redução do número de células inflamatórias.

Effects of Ciprofloxacin-Dexamethasone on Myringotomy Wound Healing

OBJECTIVE

To evaluate the effects of the ciprofloxacin-dexamethasone (CDX) combination ototopical treatment after myringotomy on tympanic membrane (TM) healing in ears with eustachian tube obstruction (ETO) and unobstructed ears.

STUDY DESIGN

Prospective, randomized, masked, controlled.

METHODS

ETO was created in the left ear of 30 rats to induce a model of otitis media with effusion (OME). After 3 weeks, bilateral myringotomy was performed (day 0). Animals were randomized into three groups to receive no treatment or bilateral once daily ototopical treatment with balanced salt solution (BSS, vehicle) or CDX for 13 days. Bilateral otomicroscopy was performed on days 7, 14, and 28. On day 14, five randomly selected animals per group were humanely euthanized and the TM harvested for histology. Three additional rats provided normal negative control ears for histologic comparisons.

RESULTS

On day 14, TM perforation healing rates were 100% in all ears of untreated and BSS-treated animals, 89% (8/9) in CDX-treated obstructed ears, and 30% (3/10) in CDX-treated unobstructed ears (P < .05 vs. BSS). On day 28, 100% (5/5) of the CDX-treated unobstructed ears and 80% (4/5) of the CDX-treated obstructed ears were healed. Histology showed initial TM thickening postmyringotomy in all ears but no significant qualitative differences between groups on day 28.

CONCLUSION

Myringotomy healing was transiently modulated by treatment with CDX but proceeded normally after CDX discontinuation. This early modulation might enhance middle ear drainage and middle ear concentrations of CDX when tympanostomy tube surgery is performed in patients with active OME and ETO, thus potentially reducing otorrhea and preventing or treating infection. It would not be expected to increase the risk of premature tube extrusion or adversely affect normal healing of the TM after usual spontaneous extrusion.

Effect of ciprodex on graft healing in tympanoplasty

The present study was conducted to evaluate whether the administration of ciprofloxacin 0.3%/dexamethasone 0.1% (Ciprodex)-soaked gelfoam during tympanoplasty has adverse effects on graft healing. Records of patients who had undergone tympanoplasty with Ciprodex-soaked gelfoam packing placed in the middle and external ear canal were reviewed. The time to heal for each patient and the number of postoperative perforations/complications were recorded. Sixty-four charts met the inclusion criteria. Most procedures were primary type I tympanoplasties with temporalis fascia grafts. Healing of the tympanic membrane was documented in 95.3% of patients, and mean time to healing was 49 d. Two patients who underwent revision tympanoplasty failed to exhibit healing at any visit after surgery. Postoperative complications were infrequent. Patients with Ciprodex-soaked gelfoam packing placed during tympanoplasty showed an overall rate of healing of 95%. Although this study is limited by its retrospective design, the data suggest that the use of Ciprodex during tympanoplasty has no detrimental effect on postoperative graft healing.

Role of TGF beta-mediated inflammation in cutaneous wound healing

Among many molecules known to influence wound healing, transforming growth factor beta 1 (TGF beta 1) has the broadest spectrum of actions, affecting all cell types that are involved in all stages of wound healing. Both positive and negative effects of TGF beta 1 on wound healing have been reported. However, the underlying mechanisms are largely unknown. We observed that endogenous TGF beta 1 was elevated in a narrow window of time after injury, and transgenic mice constitutively overexpressing wild-type TGF beta 1 in keratinocytes (K5.TGF beta 1wt) exhibited a significant delay in full-thickness wound healing as compared to non-transgenic mice. Delayed wound healing was associated with profound inflammation throughout all stages of wound healing in K5.TGF beta 1wt mice. Our data suggest that excessive and prolonged TGF beta 1 at the wound site does not benefit wound healing, which is partially owing to its pro-inflammatory effect. Future studies need to be conducted to assess whether tightly regulated TGF beta 1 expression will benefit wound healing. To this end, we have developed a gene-switch TGF beta 1 transgenic system that allows TGF beta 1 induction in keratinocytes temporally with desired levels. These mice will provide a tool to study stage-specific effects of TGF beta 1 on cutaneous wound healing.

Effect of plasma fibronectin on the incisional wound healing in rats

BACKGROUND

Abdominal wall repair after celiotomy is important because insufficient incisional wound strength results in wound failures such as fascial dehiscence and herniation. Plasma fibronectin (pFn) has been shown to play an important role in wound healing. The purpose of this study was to investigate whether pFn improves incisional wound healing in a rat skin incision and celiotomy model.

METHODS

Rats underwent a linear skin incision in the dorsal plane or a full-thickness incisional wound (celiotomy) in the abdominal wall. The same operative procedures were performed on rats whose pFn levels were reduced by antirat pFn serum. The wounds were sutured, and purified human pFn or albumin was given intravenously.

RESULTS

After the celiotomy, pFn levels decreased immediately and reached a minimum at 3 h after incision. A single injection of pFn (10 mg/kg) significantly increased the breaking strength of the skin and the bursting pressure of the abdominal wall. The amount of hydroxyproline in the skin incisional wound with pFn was significantly greater than with an injection of albumin as control. In rats with pFn levels decreased by antirat pFn serum, a single administration of pFn significantly increased the breaking strength of the skin and the bursting pressure of the abdominal wall compared to a control injection of albumin.

CONCLUSIONS

It is important for wound healing to maintain sufficiently high levels of pFn. A single intravenous injection of pFn after celiotomy may be useful in the prevention of fascial dehiscence and herniation.

The use of biomedical sensors to monitor capsule formation around soft tissue implants

Piezoelectric sensors have been shown to respond reproducibly to changes in tissue mechanical properties surrounding an implant over a 4-month period. The vibrational amplitude at a frequency corresponding to the radial resonance shows a statistically significant change over time. The initial period of inflammation is marked by a significant reduction in amplitude, which is indicative of an increase in viscous dissipation of the tissue. As collagen displaces the cellular response, the amplitude continues to decrease. Finally, as the tissue matures, the capsule becomes stiffer, and the viscous dissipation lessens. These results are consistent with qualitative assessments of explanted capsules. Strain gauges encased in a monolithic block of silicone exhibited a greater degree of variability, yet show similar trends over time. The strain increases in the initial 4-week period and remains relatively steady over the following 4 weeks. Beyond 8 weeks, the gauges begin to extrude from the animal or suffer a loss of electrical continuity. Steps are being taken to improve the strain sensor longevity in the animals.

Microarray analysis of mechanical shear effects on flexor tendon cells

BACKGROUND

Adhesion formation after flexor tendon repair remains a clinical problem. Early postoperative motion after tendon repair has been demonstrated to reduce adhesion formation while increasing tendon strength. The authors hypothesized that during mobilization, tendon cells experience mechanical shear forces that alter their biology in a fashion that reduces scar formation but also activates key genes involved in tendon healing.

METHODS

To test this hypothesis, primary intrinsic tenocyte cultures were established from flexor tendons of 20 Sprague-Dawley rats and sheared at 50 rpm (0.41 Pa) using a cone viscometer for 6 and 12 hours. Total RNA was harvested and compared with time-matched unsheared controls using cDNA microarrays and Northern blot analysis.

RESULTS

Microarray analysis demonstrated that mechanical shear stress induced an overall "antifibrotic" expression pattern with decreased transcription of collagen type I and collagen type III. Shear stress down-regulated profibrotic molecules in the platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor signaling pathways. In addition, shear stress induced an overall decrease in transforming growth factor (TGF)-beta signaling pathway molecules with down-regulation of TGF-beta2, TGF-beta3, TGF-RI, and TGF-RII expression. Moreover, sheared tendon cells increased expression of matrix metalloproteinases and decreased expression of tissue inhibitors of metalloproteinase, an expression pattern consistent with an antifibrotic increase in extracellular matrix degradation. However, the authors also found up-regulation of genes implicated in tendon healing, specifically, vascular endothelial growth factor-A and several bone morphogenetic proteins. Interestingly, the known mechanoresponsive gene, TGF-beta1, also implicated in tendon healing, was differentially up-regulated by shear stress. Northern blot validation of our results for TGF-beta1, TGF-beta2, TGF-beta3, and collagen type I demonstrated direct correlation with the authors' microarray data.

CONCLUSIONS

The authors demonstrate an overall antifibrotic expression pattern in response to shear stress in tendon cells that may provide insight into the mechanisms by which early mobilization decreases adhesion formation without impaired tendon healing.

Feitai, a Chinese herbal medicine, reduces transforming growth factor‐β1 and monocyte chemoattractant protein‐1 expression in bleomycin‐induced lung fibrosis in mice

Feitai, a Chinese medicine formulation, has been shown to protect against lung fibrosis induced by bleomycin (BLM). In the present study, we investigated the effect of Feitai on transforming growth factor (TGF)-beta1 and monocyte chemoattractant protein-1 (MCP-1), which play important roles in the pathogenesis of BLM-induced lung fibrosis. The results demonstrated that Feitai could significantly attenuate BLM-induced acute lung inflammation and subsequent lung fibrosis. Meanwhile, the expression of MCP-1 and TGF-beta1 mRNA in the lungs increased in the BLM-treated group compared with the saline-instilled control group and Feitai treatment significantly decreased cytokine expression in BLM-treated mice. In addition, Feitai diminished the accumulation of MCP-1- and TGF-beta1-positive cells in lung tissues at the time of peak mRNA levels. In summary, the results of the present study indicate that treatment with Feitai ameliorates BLM-induced lung fibrosis, at least in part via the inhibition of MCP-1 and TGF-beta1 expression.

Inhibition or knock out of inducible nitric oxide synthase result in resistance to bleomycin-induced lung injury

BACKGROUND

In the present study, by comparing the responses in wild-type mice (WT) and mice lacking (KO) the inducible (or type 2) nitric oxide synthase (iNOS), we investigated the role played by iNOS in the development of on the lung injury caused by bleomycin administration. When compared to bleomycin-treated iNOSWT mice, iNOSKO mice, which had received bleomycin, exhibited a reduced degree of the (i) lost of body weight, (ii) mortality rate, (iii) infiltration of the lung with polymorphonuclear neutrophils (MPO activity), (iv) edema formation, (v) histological evidence of lung injury, (vi) lung collagen deposition and (vii) lung Transforming Growth Factor beta1 (TGF-beta1) expression.

METHODS

Mice subjected to intratracheal administration of bleomycin developed a significant lung injury. Immunohistochemical analysis for nitrotyrosine revealed a positive staining in lungs from bleomycin-treated iNOSWT mice.

RESULTS

The intensity and degree of nitrotyrosine staining was markedly reduced in tissue section from bleomycin-iNOSKO mice. Treatment of iNOSWT mice with of GW274150, a novel, potent and selective inhibitor of iNOS activity (5 mg/kg i.p.) also significantly attenuated all of the above indicators of lung damage and inflammation.

CONCLUSION

Taken together, our results clearly demonstrate that iNOS plays an important role in the lung injury induced by bleomycin in the mice.