Effects of granulocyte-macrophage colony-stimulating factor on incisional wound healing in an experimental diabetic rat model

Effects of Recombinant Human Granulocyte/Macrophage Colony-Stimulating Factor on Diabetic Lower Extremity Ulcers: Case Series of Nine Patients

Background

Diabetic lower extremity ulcer, including diabetic foot ulcer (DFU) and leg ulcer, is one of the refractory complications of diabetes, the treatment of which is challenging, expensive, and lengthy. Recombinant Human Granulocyte/Macrophage Colony-stimulating Factor (rhGM-CSF) is an immunomodulatory cytokine that has been mainly applied in the treatment of hematological diseases. Clinical evidence regarding GM-CSF in the treatment of diabetic lower extremity ulcers is limited. This study is the first case series that investigates the repurpose effects of rhGM-CSF on diabetic ulcer healing in real clinical practice.

Methods

Nine patients diagnosed with diabetes and refractory lower extremity ulcer (ulcer duration ≥2 weeks) were included from September 2021 to February 2023 in the Division of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology. Patients with Wagner grade ≥4 and SINDAD ≥5 were excluded. The included subjects were treated with rhGM-CSF plus standard of care (SOC) including glycemic control, foot care education, debridement of necrotic tissues, topical wound dressings, offloading, and infection control when necessary. The observation endpoint was complete epithelialization. Their clinical manifestations, laboratory tests, and therapeutic effects were extracted and analyzed.

Results

The case series included 9 cases aged from 29 to 80 years and all the patients were male. Seven of 9 patients presented neuropathic ulcer. Only one case showed non-infected ulcer from tissue samples and one case presented ankle brachial index (ABI) <0.9. It was observed that the ulcer areas among these 9 patients gradually declined throughout the whole treatment period with the average healing velocity 0.32 ± 013 cm2/day and the mean time to complete healing 16.0 ± 3.7 days. The relative area (percentage of initial ulcer area) decreased to 66.7 ± 13.0% on average after the first treatment. Ulcers in all the 9 patients achieved complete epithelialization after 4-8 times treatments.

Conclusion

The case series suggests rhGM-CSF as a promising therapeutic strategy for the treatment of diabetic ulceration. More robust data from randomized controlled trials are required to further evaluate its clinical efficacy.

Biphasic photobiomodulation of inflammation in mouse models of common wounds, infected wounds, and diabetic wounds

Bidirectional photobiomodulation (PBM) therapy is an active research area. However, most studies have focused on its dependence on optical parameters rather than on its tissue-dependent effects. We constructed mouse models of wounds in three inflammatory states (normal, low, and high levels of inflammations) to assess the bidirectional regulatory effect of PBM on inflammation. Mice were divided into three groups to prepare common wounds, diabetic wounds, and bacteria-infected wounds. The same PBM protocol was used to regularly irradiate the wounds over a 14 d period. PBM promoted healing of all three kinds of wounds, but the inflammatory manifestations in each were significantly different. In common wounds, PBM slightly increased the aggregation of inflammatory cells and expression of IL-6 but had no effect on the inflammatory score. For wounds in a high level of inflammation caused by infection, PBM significantly increased TNF-α expression in the first 3 d of treatment but quickly eliminated inflammation after the acute phase. For the diabetic wounds in a low level of inflammation, PBM intervention significantly increased inflammation scores and prevented neutrophils from falling below baseline levels at the end of the 14 d observation period. Under fixed optical conditions, PBM has a bidirectional (pro- or anti-inflammatory) effect on inflammation, depending on the immune state of the target organism and the presence of inflammatory stimulants. Our results provide a basis for the formulation of clinical guidelines for PBM application.

Post-Operative Adhesions: A Comprehensive Review of Mechanisms

Post-surgical adhesions are common in almost all surgical areas and are associated with significant rates of morbidity, mortality, and increased healthcare costs, especially when a patient requires repeat operative interventions. Many groups have studied the mechanisms driving post-surgical adhesion formation. Despite continued advancements, we are yet to identify a prevailing mechanism. It is highly likely that post-operative adhesions have a multifactorial etiology. This complex pathophysiology, coupled with our incomplete understanding of the underlying pathways, has resulted in therapeutic options that have failed to demonstrate safety and efficacy on a consistent basis. The translation of findings from basic and preclinical research into robust clinical trials has also remained elusive. Herein, we present and contextualize the latest findings surrounding mechanisms that have been implicated in post-surgical adhesion formation.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Human Cord Blood-Derived Unrestricted Somatic Stem Cells Promote Wound Healing and have Therapeutic Potential for Patients with Recessive Dystrophic Epidermolysis Bullosa

Human umbilical cord blood (CB)-derived unrestricted somatic stem cells (USSCs) have previously been demonstrated to have a broad differentiation potential and regenerative beneficial effects when administered in animal models of multiple degenerative diseases. Here we demonstrated that USSCs could be induced to express genes that hallmark keratinocyte differentiation. We also demonstrated that USSCs express type VII collagen (C7), a protein that is absent or defective in patients with an inherited skin disease, recessive dystrophic epidermolysis bullosa (RDEB). In mice with full-thickness excisional wounds, a single intradermal injection of USSCs at a 1-cm distance to the wound edge resulted in significantly accelerated wound healing. USSC-treated wounds displayed a higher density of CD31+ cells, and the wounds healed with a significant increase in skin appendages. These beneficial effects were demonstrated without apparent differentiation of the injected USSCs into keratinocytes or endothelial cells. In vivo bioluminescent imaging (BLI) revealed specific migration of USSCs modified with a luciferase reporter gene, from a distant intradermal injection site to the wound, as well as following systemic injection of USSCs. These data suggest that CB-derived USSCs could significantly contribute to wound repair and be potentially used in cell therapy for patients with RDEB.

Granulocyte/macrophage colony-stimulating factor influences angiogenesis by regulating the coordinated expression of VEGF and the Ang/Tie system

Granulocyte/macrophage colony-stimulating factor (GM-CSF) can accelerate wound healing by promoting angiogenesis. The biological effects of GM-CSF in angiogenesis and the corresponding underlying molecular mechanisms, including in the early stages of primitive endothelial tubule formation and the later stages of new vessel maturation, have only been partially clarified. This study aimed to investigate the effects of GM-CSF on angiogenesis and its regulatory mechanisms. Employing a self-controlled model (Sprague-Dawley rats with deep partial-thickness burn wounds), we determined that GM-CSF can increase VEGF expression and decrease the expression ratio of Ang-1/Ang-2 and the phosphorylation of Tie-2 in the early stages of the wound healing process, which promotes the degradation of the basement membrane and the proliferation of endothelial cells. At later stages of wound healing, GM-CSF can increase the expression ratio of Ang-1/Ang-2 and the phosphorylation of Tie-2 and maintain a high VEGF expression level. Consequently, pericyte coverages were higher, and the basement membrane became more integrated in new blood vessels, which enhanced the barrier function of blood vessels. In summary, we report here that increased angiogenesis is associated with GM-CSF treatment, and we indicate that VEGF and the Ang/Tie system may act as angiogenic mediators of the healing effect of GM-CSF on burn wounds.

Imbalance of apoptosis and cell proliferation contributes to the development and persistence of emphysema

BACKGROUND

We postulate that in adults there is an established lung structure maintenance program and that lung alveolar septal cells are undergoing both continuous apoptosis and proliferation. Whereas lung cell apoptosis has been recognized in human emphysema, little is known about cell proliferation.

METHODS

Using a novel rat model of emphysema, induced by intratracheal instillation of cigarette smoke extract (CSE), we investigated the dynamics of emphysematous lung destruction. Emphysematous lung destruction was determined by measuring mean linear intercept and destructive index. Lung injury and repair were assessed by immunohistochemistry and Western blot analysis for active caspase-3 and proliferating cell nuclear antigen (PCNA) after 4, 8, and 12 weeks of CSE instillations.

RESULTS

The emphysematous lung tissue destruction was present at 4 weeks of CSE treatment and progressed to 8 weeks. Spontaneous repair began at 12 weeks. Treatment with a peroxisome proliferator activated receptor (PPAR)α+γ agonist or granulocyte and macrophage-colony stimulating factor (GM-CSF) for 4 weeks prevented the progression of emphysematous lung destruction and decreased the number of caspase-3-positive cells.

CONCLUSION

Apoptosis and cell proliferation occur in this new model of emphysema. Treatment with a PPARα+γ agonist or GM-CSF can inhibit the progression of emphysematous alveolar septal destruction by decreasing alveolar cell apoptosis.

Propofol inhibits pressure-stimulated macrophage phagocytosis via the GABAA receptor and dysregulation of p130cas phosphorylation

Surgical stress and anesthesia result in systemic immunosuppression. Propofol, a commonly used anesthetic agent, alters immune cell functions. Previously, we demonstrated that extracellular pressure increases macrophage phagocytosis. We hypothesized that propofol might influence pressure-induced macrophage phagocytosis in monocytes from patients undergoing surgery. Pressure (20 mmHg above ambient pressure) augmented phagocytosis in monocytes from non-propofol-anesthetized patients but reduced phagocytosis in monocytes from propofol-anesthetized patients. In vitro, propofol stimulated phagocytosis but reversed pressure-induced phagocytosis in THP-1 macrophages and monocytes from healthy volunteers. The GABA(A) receptor antagonists picrotoxin and SR-95531 did not affect basal THP-1 phagocytosis or prevent pressure-stimulated phagocytosis. However, picrotoxin and SR-95531 negated the inhibitory effect of pressure in propofol-treated cells without altering propofol-induced phagocytosis. Phosphorylation of the adaptor protein p130cas was inversely related to phagocytosis: it was inhibited by pressure or propofol but increased by pressure + propofol compared with propofol alone. Reduction of p130cas by small interfering RNA in THP-1 macrophages increased basal phagocytosis and prevented pressure and propofol effects. In conclusion, propofol may alter macrophage responses to pressure via the GABA(A) receptor and p130cas, whereas pressure also acts via p130cas but independently of GABA(A) receptors. p130cas may be an important target for modulation of macrophage function in anesthetized patients.

The effects of topical granulocyte-macrophage colony-stimulating factor on dural healing in rats after induced cerebrospinal fluid leakage

OBJECT

Dural defects must be repaired to protect the central nervous system from contamination. Although there are various experimental and commercial substances available for this purpose, the ultimate method of watertight dural closure has yet to be discovered. In this study, the authors investigate the effects of topically applied recombinant mouse granulocyte-macrophage colony-stimulating factor (GM-CSF) on dural healing in a rat model of dural injury and cerebrospinal fluid leakage.

METHODS

In this experimental model, a dural defect at the level of the L1-2 vertebrae was created in 32 Wistar rats. Sixteen animals were treated with locally applied recombinant mouse GM-CSF postoperatively, and 16 animals received normal saline. The effects of GM-CSF on dural healing, cerebrospinal fluid leakage, and wound healing were assessed 2 and 4 weeks postoperatively. Dural healing was evaluated histologically.

RESULTS

Dural healing was increased in rats treated with GM-CSF compared with rats in the control group. This difference was statistically significant (p < 0.05).

CONCLUSIONS

Cerebrospinal fluid leakage may impede healing of dural defects. Topically applied GM-CSF seems to aid in dural healing.

Granulocyte-macrophage colony-stimulating factor is essential for normal wound healing

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multipotent growth factor, which plays an important role during the process of wound healing. In clinical settings it has occasionally been employed in the treatment of cutaneous wounds of diverse etiologies. In a previous study, we have shown the positive influence of GM-CSF on full thickness excisional wounds in transgenic mice overexpressing GM-CSF in the basal layer of the epidermis. Direct GM-CSF action as well as indirect processes through the induction of secondary cytokines were proposed to contribute towards the beneficial effects. In this study, we analyzed the process of wound healing in transgenic mice overexpressing a GM-CSF antagonist in the epidermis. These mice not only exhibited a delayed scab rejection and reepithelialization but also neovascularization was reduced. The newly formed tissue was of poor quality as exhibited by the presence of extensive fibrosis. We suggest that the presence of GM-CSF in the repair process is of basic importance and its absence leads not only to delayed wound healing but it is also detrimental for the quality of the newly formed tissue.

The molecular biology of chronic wounds and delayed healing in diabetes

Wound healing is a complicated and integrated process. Although there is some tolerance in terms of redundancy and interrelated control mechanisms, pushing beyond such limits may contribute to delayed wound healing, and in extreme cases lead to chronic wounds/ulcers and thus potentially to lower extremity amputation. Diabetes is associated with such disruption in wound healing. Research in humans and in animal models has identified a large number of changes associated with diabetes at the molecular level in delayed wound healing and to a lesser extent in chronic diabetic ulcers. Better overall understanding of these changes and how they are interrelated would allow for specifically targeted treatment, thus ensuring improved quality of life for patients and providing savings to the high costs that are associated with all aspects of chronic diabetic ulcers. This review examines the work done at the molecular level on chronic diabetic ulcers, as well as considering changes seen in diabetes in general, both in humans and animal models, that may in turn contribute to ulcer formation.

Granulocyte/macrophage colony-stimulating factor treatment of human chronic ulcers promotes angiogenesis associated with de novo vascular endothelial growth factor transcription in the ulcer bed

Summary Background Granulocyte/macrophage colony-stimulating factor (GM-CSF), a cytokine with pleiotropic functions, has been successfully employed in the treatment of chronic skin ulcers. The biological effects underlying GM-CSF action in impaired wound healing have been only partly clarified. Objectives To investigate the effects of GM-CSF treatment of chronic venous ulcers on lesion vascularization and on the local synthesis of the angiogenic factors vascular endothelial growth factor (VEGF) and placenta growth factor (PlGF). Methods Patients with nonhealing venous leg ulcers were treated with intradermal injection of recombinant human GM-CSF, and biopsies were taken at the ulcer margin before and 5 days after administration. Wound vascularization was analysed by immunohistochemistry using antiplatelet endothelial cell adhesion molecule-1/CD31 and anti-alpha-smooth muscle actin antibodies. VEGF and PlGF transcription was assessed by in situ hybridization. To identify the cell populations transcribing VEGF within the ulcer bed, the VEGF hybridization signal was correlated with the immunostaining for different cell type markers on serial sections. Direct induction of VEGF transcription by GM-CSF was investigated in GM-CSF-treated cultured macrophages and keratinocytes. Results Blood vessel density was significantly increased in the ulcer bed following GM-CSF treatment. VEGF transcripts were localized in keratinocytes at the ulcer margin both before and after GM-CSF treatment, whereas a VEGF hybridization signal was evident within the ulcer bed only following administration. PlGF mRNA was barely detectable in keratinocytes at the ulcer margin and was not visibly increased after treatment. Unlike VEGF, a specific PlGF hybridization signal could not be detected in cells within the ulcer following GM-CSF administration. Monocytes/macrophages were the main cell population transcribing VEGF after GM-CSF treatment. In vitro analysis demonstrated that VEGF transcription can be directly stimulated by GM-CSF in a differentiated monocytic cell line, but not in keratinocytes. Conclusions Our data show that increased vascularization is associated with GM-CSF treatment of chronic venous ulcers and indicate that inflammatory cell-derived VEGF may act as an angiogenic mediator of the healing effect of GM-CSF in chronic ulcers.

Differential effects of PDGF-BB on matrix metalloproteases and cytokine release in fibroblasts of Type 2 diabetic patients and normal controls in vitro

AIMS/HYPOTHESIS

The complex process of wound healing is regulated by various growth factors. The systemic character of diabetes mellitus favors the chronification of diabetic wounds. In this study, the in vitro effects of platelet-derived growth factor (PDGF)-BB on the expression of cytokines and matrix metalloproteases (MMPs) in fibroblasts of Type 2 diabetic patients and healthy controls were investigated.

METHODS

We studied six Type 2 diabetic patients (mean Hba1(c)=7.5%) and six healthy controls. For proliferation studies, cultivated fibroblasts, prepared from biopsies taken from the thigh, were stimulated with different concentrations of PDGF. After 48 h, the expression of MMPs and cytokines was measured. We analysed the mRNA expression by RT-PCR (TaqMan), tissue protein levels by zymography, and cell supernatant levels by ELISA.

RESULTS

Levels of MMP-mRNA were elevated in diabetic fibroblasts compared with healthy controls. At baseline, MMP-2 protein levels were significantly increased in the fibroblast of diabetic patients (P=.019). For MMP-9, a trend towards higher levels (P=.3) was found. After incubation with PDGF, a significant reduction of MMP-9 (P=.01) and MMP-13 (P=.04) was found. Analysis of cytokine release in cell culture supernatant showed elevated levels of interleukin (IL)-8 at baseline conditions. MMP-1 and MMP-2 levels in the supernatant were concentration-dependently reduced.

CONCLUSIONS

This study, for the first time, demonstrates elevated MMPs in cultivated fibroblasts (derived from intact skin and not from an open wound) of diabetic patients compared with healthy controls under in vitro conditions. Therefore, our data support the hypothesis of alterations of wound healing in diabetic patients on the cellular level, reflecting the systemic character of the disease.

17beta-estradiol enhances the production of granulocyte-macrophage colony-stimulating factor in human keratinocytes

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is effective for impaired wound repair. Estrogen is known to enhance wound repair. We examined if 17beta-estradiol (E2) may in vitro enhance GM-CSF production in human keratinocytes. E2 and membrane-impermeable bovine serum albumin-conjugated E2 increased GM-CSF secretion, mRNA stability, and promoter activity. The element homologous to activator protein-1 (AP-1) on the promoter was responsible for the activation. E2 enhanced transcriptional activity and DNA binding of AP-1. E2 transiently generated c-Fos protein, and shifted AP-1 composition from c-Jun homodimers to c-Fos/c-Jun heterodimers in keratinocytes. E2-induced enhancement of GM-CSF secretion, mRNA stability, and promoter activity were not suppressed by estrogen receptor antagonist ICI 182,780, however, suppressed by conventional protein kinase C inhibitor Gö6976 and PD98059, an inhibitor of mitogen-activated protein kinase kinase (MEK). Gö6976 and PD98059 suppressed E2-induced c-Fos expression and enhancement of DNA-binding and transcriptional activity at AP-1. E2 induced membrane translocation of protein kinase Calpha, which was suppressed by phosphatidylinositol (PI)-specific phospholipase C (PLC) inhibitor U73122. E2 stimulated the phosphorylation of extracellular signal-regulated kinase (ERK), which was suppressed by PD98059, Gö6976, and U73122. E2 transiently generated inositol 1,4,5-triphosphate in keratinocytes, which was suppressed by U73122 and guanine nucleotide-binding protein inhibitor. These results suggest that E2 may enhance GM-CSF production via guanine nucleotide-binding protein-coupled membrane receptors and signaling cascade of PI-specific PLC/protein kinase Calpha/MEK/ERK.

Alterations in the vascular extracellular matrix of granulocyte macrophage colony-stimulating factor (GM-CSF) -deficient mice

GM-CSF takes part in the cytokine network regulating the metabolism of extracellular matrix (ECM) during atherogenesis. Since data also point to an effect of GM-CSF on the vascular ECM in general, the vascular collagenous matrix was studied in wild-type and GM-CSF-deficient mice. Histological examination revealed a disorganized vascular ECM in GM-CSF-deficient mice involving the collagenous matrix and elastic fiber system. As shown by electron microscopy, collagen bundles were disrupted and reduced. The diameter of fibrils varied widely. mRNA expression of collagens and related molecules was studied. Fibrillar collagens were markedly reduced, alpha1(I)procollagen to 16.5% of control levels alpha1(III)procollagen was abolished whereas the expression level of network-forming alpha1(VIII)procollagen was not altered. As shown by in situ hybridization, the number of collagen-expressing cells was reduced. Matrix metalloproteinases and their inhibitor 1 were not affected by GM-CSF deficiency. Our studies demonstrate that GM-CSF plays a major role in the cytokine network regulating the metabolism of vascular collagens. GM-CSF deficiency leads to an altered composition of the vascular collagenous matrix, i.e., reduced amount of fibrillar collagen, altered ratio of fibrillar and network-forming collagen, and failures in the fibrillogenesis. We suggest that GM-CSF is a basic requirement for the maintenance of vessel wall integrity and resilience.

Impaired synthesis of prostaglandin E2 by lung fibroblasts and alveolar epithelial cells from GM-CSF-/- mice: implications for fibroproliferation

Prostaglandin E(2) (PGE(2)) is a potent suppressor of fibroblast activity. We previously reported that bleomycin-induced pulmonary fibrosis was exaggerated in granulocyte-macrophage colony-stimulating factor knockout (GM-CSF(-/-)) mice compared with wild-type (GM-CSF(+/+)) mice and that increased fibrosis was associated with decreased PGE(2) levels in lung homogenates and alveolar macrophage cultures. Pulmonary fibroblasts and alveolar epithelial cells (AECs) represent additional cellular sources of PGE(2) within the lung. Therefore, we examined fibroblasts and AECs from GM-CSF(-/-) mice, and we found that they elaborated significantly less PGE(2) than did cells from GM-CSF(+/+) mice. This defect was associated with reduced expression of cyclooxygenase-1 and -2 (COX-1 and COX-2), key enzymes in the biosynthesis of PGE(2). Additionally, proliferation of GM-CSF(-/-) fibroblasts was greater than that of GM-CSF(+/+) fibroblasts, and GM-CSF(-/-) AECs were impaired in their ability to inhibit fibroblast proliferation in coculture. The addition of GM-CSF to fibroblasts from GM-CSF(-/-) mice increased PGE(2) production and decreased proliferation. Similarly, AECs isolated from GM-CSF(-/-) mice with transgenic expression of GM-CSF under the surfactant protein C promoter (SpC-GM mice) produced more PGE(2) than did AEC from control mice. Finally, SpC-GM mice were protected from fluorescein isothiocyanate-induced pulmonary fibrosis. In conclusion, these data demonstrate that GM-CSF regulates PGE(2) production in pulmonary fibroblasts and AECs and thus plays an important role in limiting fibroproliferation.

Supplemental L-arginine enhances wound healing in diabetic rats

L-arginine has been shown to enhance wound strength and collagen deposition in rodents and humans. Diabetes mellitus, which impairs wound healing, is accompanied by a reduction in nitric oxide at the wound site. The amino acid L-arginine is the only substrate for nitric oxide synthesis. We sought to determine whether supplemental L-arginine can restore the impaired wound healing of diabetic rats. Fifty-six male Lewis rats were used in this study, of which twenty-nine rats were rendered diabetic 7 days prior to surgery with intraperitoneal streptozotocin. Twenty-seven untreated rats served as controls. Animals underwent a dorsal skin incision with implantation of polyvinyl-alcohol sponges. Sixteen diabetic and 14 normal rats received 1 g/kg/day of L-arginine by injection, while the remainder received saline injections only. Animals were euthanized 10 days postwounding, and their wounds were analyzed for breaking strength. The wound sponges were assayed for total hydroxyproline and nitrite/nitrate content. Plasma and wound fluid concentrations of L-arginine, ornithine, and citrulline were determined. Wound sponge RNA was extracted and subjected to Northern blot analysis for procollagen I and III. Diabetic wounds had greatly decreased breaking strengths compared with controls. L-arginine significantly enhanced wound breaking strengths in both control (+23%) and diabetic animals (+44%), and also increased wound hydroxyproline levels in both diabetic (+40%) and control animals (+24%) as compared to their saline-treated counterparts. mRNA for procollagen I and III were elevated by L-arginine treatment in both diabetic rats and controls. Treatment with L-arginine significantly increased wound fluid nitrite/nitrate levels in diabetic animals. The data show that the impaired healing of diabetic wounds can be partially corrected by L-arginine supplementation, and that this effect is accompanied by enhanced wound nitric oxide synthesis.

GM-CSF increases airway smooth muscle cell connective tissue expression by inducing TGF-beta receptors

Fibrosis around the smooth muscle of asthmatic airway walls leads to irreversible airway obstruction. Bronchial epithelial cells release granulocyte/macrophage colony-stimulating factor (GM-CSF) in asthmatics and are in close proximity to airway smooth muscle cells (ASMC). The findings in this study demonstrate that GM-CSF induces confluent, prolonged, serum-deprived cultures of ASMC to increase expression of collagen I and fibronectin. GM-CSF also induced ASMC to increase the expression of transforming growth factor (TGF)-beta receptors type I, II, and III (TbetaR-I, TbetaR-II, TbetaR-III), but had no detectable effect on the release of TGF-beta1 by the same ASMC. The presence of GM-CSF also induced the association of TGF-beta1 with TbetaR-III, which enhances binding of TGF-beta1 to TbetaR-II. The induction of TbetaRs was parallel to the increased induction of phosphorylated Smad2 (pSmad2) and connective tissue growth factor (CTGF), indicative of TGF-beta-mediated connective tissue synthesis. Dexamethasone decreased GM-CSF-induced TbetaR-I, TbetaR-II, TbetaR-III, pSmad2, CTGF, collagen I, and fibronectin. In conclusion, GM-CSF increases the responsiveness of ASMC to TGF-beta1-mediated connective tissue expression by induction of TbetaRs, which is inhibited by corticosteroids.

The role of L-arginine and neutrophils on incisional wound healing

Although arginine plays an important role in many aspects of inflammation and wound healing, the mechanism is not clear. We aimed to evaluate the effect of L-arginine administration on wound healing and neutrophil activity and on the interaction of these effects. Sixteen rats were divided into two groups: control group and L-arginine group. L-arginine was given intraperitoneally. The rats underwent incisional wounding and were killed on the 7th day of wounding. Blood neutrophil counts, neutrophil adhesivity index, tensile strengths and hydroxyproline level of skin were determined, histopathological and electron microscopical evaluation of healing was performed. Wound scores in the control group were significantly lower (p < 0.05). Hydroxyproline and collagen levels of skin were significantly increased in the L-arginine group (p < 0.05). Blood neutrophil counts and neutrophil adhesivity index in the L-arginine group were significantly increased (p < 0.05), as were the inflammatory cells in the skin. L-arginine may be used during the first phase of healing to induce inflammation in high risk patients.

Effects of rhG-CSF on neutrophil functions and bone marrow parameters in diabetic rats

Neutrophils have an important role in the host defense. The elevated serum glucose levels of diabetics affect traditional host defenses such as neutrophil counts and functions. The causes of these impairments are not clear. We aimed to investigate changes of peripheral neutrophil counts and functions and their relation with bone marrow cells in diabetic rats. Thirty-two rats were divided into four equal groups. Group 1 were controls and Groups 2 and 4 were made diabetic by a single intraperitoneal injection of streptozotocin. Granulocyte colony stimulating factor (G-CSF) was injected subcutaneously into Groups 3 and 4. White blood cell count, neutrophil counts and function and bone marrow cell count were determined. Peripheral blood cell counts, neutrophil phagocytosis index were decreased but neutrophil adhesivity index was not different in the diabetes-induced group. There was a difference in circulating white blood cell counts and neutrophil counts between the rhG-CSF treated and non-treated groups. The phagocytosis index of neutrophil in diabetic rats was significantly diminished by rhG-CSF treatment. A hyperplasia of early cells of the myeloid series in G-CSF treated groups was observed when compared with those of nontreated groups (p<0.001). A significant decrease was noted in the number of mature marrow segmented cells diabetic groups (p<0.001). Finally, G-CSF has been shown to cause neutrophilia by acting as a releasing factor for mature marrow neutrophils in diabetic rats. These results suggest that G-CSF may be used to improve nonspecific immunity in diabetic patients.