Platelet-derived growth factor

Analysis of hepatic fibrosis markers in the serum of chronic hepatitis B patients according to basal core promoter/precore mutants

The A1762T/G1764A double mutant in the basal core promoter (BCP) region of the hepatitis B virus (HBV) is associated with severe hepatic lesions while the G1899A mutation with the double mutant is associated with a significant reduction in the risk of severe fibrosis. This study aims to measure a number of markers in the serum of patients with chronic HBV infection and to assess relationships between these markers and BCP/precore mutants with consideration of the stage of fibrosis. The serum levels of resistin, TGF-β1, MMP-1, TIMP-1, collagen IA1 and PDGF-BB, which are markers that are known to be involved in the process of hepatic fibrosis, were assayed. The serum levels of PDGF-BB and TIMP-1, and the mutation profile were independently associated with advanced fibrosis. A higher level of TIMP-1 was associated with advanced fibrosis regardless of the mutation status, and a higher level of PDGF-BB was associated with nonsevere fibrosis in patients infected with viruses harboring the A1762T/G1764A or A1762T/G1764A/G1899A mutations. Our results suggest an impact of the A1762T/G1764A mutant on the biological pathway related to TGF-β1 and PDGF-BB. In vitro studies are needed to understand the impact of these mutants on the serum secretion of markers involved in fibrosis severity.

An Overview of Privileged Scaffold: Quinolines and Isoquinolines in Medicinal Chemistry as Anticancer Agents

Cancer is one of the most difficult diseases and causes of death for many decades. Many pieces of research are continuously going on to get a solution for cancer. Quinoline and isoquinoline derivatives have shown their possibilities to work as an antitumor agent in anticancer treatment. The members of this privileged scaffold quinoline and isoquinoline have shown their controlling impacts on cancer treatment through various modes. In particular, this review suggests the current scenario of quinoline and isoquinoline derivatives as antitumor agents and refine the path of these derivatives to find and develop new drugs against an evil known as cancer.

Cx43 and AKAP95 regulate G1/S conversion by competitively binding to cyclin E1/E2 in lung cancer cells

Background

This study aimed to overexpress or silence connexin 43 (Cx43) and A‐kinase anchoring protein 95 (AKAP95) in human A549 cells to explore their effects on cyclins and on G1/S conversion when the interrelationship of Cx43, AKAP95, and cyclin E1/E2 changes.

Methods

The study mainly used Western blot analysis and Co‐immuno precipitation to detect the target protein in Cx43/AKAP95 over expressed human A549 cells, and the relationship of proteins Cx43, AKAP95 and Cyclin E during G1‐S phase was explored with qualitative and quantitative analysis.

Results

The overexpression of Cx43 inhibited the expression of cyclin D1 and E1 by accelerating their degradation and reduced the Cdk2 activity that blocked the DNA transcription activity. However, the overexpression of AKAP95 increased the expression of cyclin D1 and E1 and inhibited their degradation, and enhanced the Cdk2 activity that promoted the DNA transcription activity. Cx43 and AKAP95 competitively bound to cyclin E1/E2, and the competitive binding affected the Cdk2 activity, Rb phosphorylation, DNA transcription activity, and G1/S conversion.

Conclusions

This study showed that the expression of ERK1/2, PKA, and PKB increased when BEAS‐2B cells were treated with PDGF‐BB, suggesting that ERK1/2, PKA, and PKB might be involved in the binding of AKAP95 with cyclin E, or the separation of AKAP95 from Cx43 from cyclin E1/E2. The specific mechanism underlying this process still needs further exploration.

Platelet-Derived Growth Factor C in Alcoholics

AIMS

Platelet-derived growth factor (PDGF) promotes liver collagen deposition, acting on hepatic stellate cells. Despite this, low serum PDGF levels were reported in chronic hepatitis C or B infection, although some studies yield the opposite result. Since PDGF may be related not only to fibrosis but also with vascular, neuronal or muscle disease, it is important to analyze its behavior in alcoholics.

METHODS

In total, 17 controls and 62 alcoholic patients consecutively admitted to the hospitalization unit of the Internal Medicine Service were included. We determined serum levels of PDGF C, routine laboratory evaluation, tumor necrosis factor-α, interleukin (IL)-6 and IL-8 and malondialdehyde (MDA) levels. We analyzed the relationships between PDGF and liver function, ethanol intake and inflammatory reaction by both univariate and multivariate analysis to discern which variables PDGF levels depend on.

RESULTS

Serum PDGF levels were significantly lower among patients (675 ± 466 pg/ml) than among controls (1074 ± 337 pg/ml; Z = 3.70; P < 0.001), and even lower among cirrhotics (549 ± 412 among cirrhotics vs 778 ± 487 among non-cirrhotics; Z = 2.33; P = 0.02). PDGF levels showed a direct correlation with prothrombin activity (ρ = 0.50; P < 0.001), platelet count (ρ = 0.44; P < 0.001) and inverse ones with bilirubin (ρ = -0.39; P = 0.002), IL-6 (ρ = -0.33; P = 0.016), IL-8 (ρ = -0.47; P < 0.001), and MDA levels (ρ = -0.44; P < 0.001). By multivariate analysis, only prothrombin activity and platelet count were independently related to PDGF.

CONCLUSION

PDGF-C levels are decreased in alcoholics, especially among cirrhotics. Multivariate analysis discloses that only prothrombin activity and platelet count are independently related to PDGF-C levels.

Serum cytokines, adipokines and ferritin for non-invasive assessment of liver fibrosis in chronic liver disease: a systematic review

Chronic liver disease (CLD) is a major health problem worldwide. Non-alcoholic fatty liver disease (NAFLD), chronic hepatitis C (CHC), chronic hepatitis B (CHB), and alcoholic liver disease (ALD) are the most common etiologies of CLD. Liver biopsy is the gold standard for assessment of liver fibrosis, however, it is an invasive method. This review attempts to evaluate the usefulness of serum adiponectin, serum leptin, serum ferritin, serum transforming growth factor-β1 (TGF-β1), and serum platelet derived growth factor-BB (PDGF-BB) as non-invasive markers in the diagnosis of liver fibrosis/cirrhosis. A systematic search in MEDLINE, Web of Science, Scopus, and local databases was performed to identify articles published in English or Persian as of November 2017. Studies conducted among CLD patients, with biopsy proven fibrosis/cirrhosis, and providing sufficient details of patients' clinicopathological characteristics were included. In the 95 studies included, there were a total of 15,548 CLD patients. More than 83% of studies were carried out in Asia and Europe. The relationship between liver fibrosis/cirrhosis and serum levels of ferritin, adiponectin, leptin, TGF-β1, and PDGF-BB was assessed in 42, 33, 27, nine, and three studies, respectively. Serum levels of the markers, particularly ferritin, could successfully predict liver fibrosis/cirrhosis, however, these data might not be clinically replicated and further studies are needed.

The effects of autologous platelet concentrate on the healing of intra-bony defects: a randomized clinical trial

Purpose

The present study aimed to evaluate the clinical and radiographic effects of autologous platelet concentrate (APC) on the healing of intra-bony defects filled with β-tricalcium phosphate (β-TCP) and covered with collagen membranes.

Subjects and methods

This study included 30 defects of 14 systemically healthy subjects. All of them had, at least, two deep intra-bony, inter-proximal periodontal defects. Minimum probing pocket depth (PPD) was 6 mm. Clinical and imaging examination was performed both at baseline and at 3, 6, and 9 months after surgery.

Results

Both the test and control group revealed a significant reduction in all variables when compared with the base line. Mean reduction of the PPD in two groups at each follow-up time point showed no significant difference. Means of the clinical attachment gain of the same groups were significantly different (p<0.05). Mean gingival recession at 3 month was not significant. However, the means of gingival recession coverage of two groups were significantly different at 6 and 9 months (p<0.05 for both).

Conclusion

Sites treated with APC are more likely to demonstrate more clinical attachment gain and recession coverage at the end of 9 month compared to those without APC.

A review of inflammatory mechanism in airway diseases

BACKGROUND

Inflammation in the lung is the body's natural response to injury. It acts to remove harmful stimuli such as pathogens, irritants, and damaged cells and initiate the healing process. Acute and chronic pulmonary inflammation are seen in different respiratory diseases such as; acute respiratory distress syndrome, chronic obstructive pulmonary disease (COPD), asthma, and cystic fibrosis (CF).

FINDINGS

In this review, we found that inflammatory response in COPD is determined by the activation of epithelial cells and macrophages in the respiratory tract. Epithelial cells and macrophages discharge transforming growth factor-β (TGF-β), which trigger fibroblast proliferation and tissue remodeling. Asthma leads to airway hyper-responsiveness, obstruction, mucus hyper-production, and airway-wall remodeling. Cytokines, allergens, chemokines, and infectious agents are the main stimuli that activate signaling pathways in epithelial cells in asthma. Mutation of the CF transmembrane conductance regulator (CFTR) gene results in CF. Mutations in CFTR influence the lung epithelial innate immune function that leads to exaggerated and ineffective airway inflammation that fails to abolish pulmonary pathogens. We present mechanistic computational models (based on ordinary differential equations, partial differential equations and agent-based models) that have been applied in studying the complex physiological and pathological mechanisms of chronic inflammation in different airway diseases.

CONCLUSION

The scope of the present review is to explore the inflammatory mechanism in airway diseases and highlight the influence of aging on airways' inflammation mechanism. The main goal of this review is to encourage research collaborations between experimentalist and modelers to promote our understanding of the physiological and pathological mechanisms that control inflammation in different airway diseases.

Pulmonary Hypoplasia Induced by Oligohydramnios: Findings from Animal Models and a Population-Based Study

Pulmonary hypoplasia is a substantial cause of death in newborn infants, and oligohydramnios is one of the most commonly associated abnormalities. Lung growth is influenced by physical factors such as the intrauterine space, lung liquid volume and pressure, and fetal breathing movements. During lung development, the main physical force experienced by the lungs is stretching induced by breathing movements and the lung fluid in the airspaces. Oligohydramnios reduces the intrathoracic cavity size, thus disrupting fetal lung growth and leading to pulmonary hypoplasia. The exact mechanism by which oligohydramnios alters the respiratory system structure and the effect of oligohydramnios on long-term respiratory outcomes remain unknown. In this review, we summarize the effects of oligohydramnios on lung development, discuss the mechanisms of oligohydramnios-induced pulmonary hypoplasia identified in various animal studies, and describe the long-term respiratory outcomes in childhood of oligohydramnios-exposed fetuses reported by a population-based study.

Cost-Effectiveness of Becaplermin Gel on Diabetic Foot Ulcer HealingChanges in Wound Surface Area

BACKGROUND

A comparison of the cost-effectiveness of becaplermin plus good wound care (BGWC) versus good wound care (GWC) alone in treating patients with diabetic foot ulcers (DFUs) may enable physicians and health-care decision makers in the United States to make better-informed choices about treating DFUs, which currently contribute to a substantial portion of the economic burden of diabetes.

METHODS

Data from three phase III trials were used to predict expected 1-year costs and outcomes, including the average percentage reduction from baseline in wound surface area (WSA), the direct costs of DFU therapy, and the cost per cm(2) of WSA reduction.

RESULTS

At 20 weeks, the BGWC group had a statistically greater probability of complete wound closure than the GWC group (50% versus 35%; P = .015). Based on reported WSA reduction rates, DFUs in the BGWC group were predicted to close by 100% at 27 weeks, and those in the GWC group were predicted to close by 88% at 52 weeks. The GWC group had higher total estimated 1-year direct cost of DFU care ($6,809 versus $4,414) and higher cost per cm(2) of wound closure ($3,501 versus $2,006).

CONCLUSIONS

Becaplermin plus good wound care demonstrated economic dominance compared with GWC by providing better clinical outcomes via faster reduction in WSA and higher rates of closure at a lower direct cost.

Promoting Diabetic Wound Therapy Using Biodegradable rhPDGF-Loaded Nanofibrous Membranes: CONSORT-Compliant Article

The nanofibrous biodegradable drug-loaded membranes that sustainably released recombinant human platelet-derived growth factor (rhPDGF-BB) to repair diabetic wounds were developed in this work.rhPDGF-BB and poly(lactic-co-glycolic acid) (PLGA) were mixed in hexafluoroisopropyl alcohol, followed by the electrospinning of the solutions into biodegradable membranes to equip the nanofibrous membranes. An elution technique and an enzyme-linked immunosorbent assay kit were used to determine the rhPDGF-BB release rates in vitro and in vivo from this membrane. Eighteen Sprague-Dawley streptozotocin-induced diabetic rats were randomized into 3 groups: rhPDGF-BB-loaded nanofibrous membrane group, PLGA only membrane group, and conventional gauze sponge group for the wound associated with diabetes of rat in each group.The nanofibrous biodegradable membranes released effective concentrations of rhPDGF-BB for over 21 days. The nanofibrous rhPDGF-BB-loaded PLGA membranes contained more water and were further hydrophilic than PLGA only fibers. The rhPDGF-BB-loaded PLGA membranes considerably helped the diabetic wounds repairing. Furthermore, the proliferative cells and angiogenesis of rats associated with diabetes by rhPDGF-BB-loaded nanofibrous membranes were greater than those of other groups, owing to the increased matrix metalloproteinase 9.These biodegradable rhPDGF-BB-loaded membranes were effective in treating diabetic wounds as very advanced accelerators during the initial phases of wound-healing process.

Longitudinal effects of menopausal hormone treatments on platelet characteristics and cell-derived microvesicles

Activated platelets serve as a catalyst for thrombin generation and a source of vasoactive and mitogenic factors affecting vascular remodeling. Oral menopausal hormone treatments (MHT) may carry greater thrombotic risk than transdermal products. This study compared effects of oral and transdermal MHT on platelet characteristics, platelet proteins, and platelet-derived microvesicles (MV) in recently menopausal women. Platelets and MV were prepared from blood of a subset of women (n = 117) enrolled in the Kronos Early Estrogen Prevention Study prior to and after 48 months of treatment with either oral conjugated equine estrogen (0.45 mg/day), transdermal 17β-estradiol (50 µg/day), each with intermittent progesterone (200 mg/day for 12 days a month), or placebo pills and patch. Platelet count and expression of platelet P-selectin and fibrinogen receptors were similar across groups. An aggregate measure of 4-year change in vasoactive and mitogenic factors in platelet lysate, by principle component analysis, indicated significantly lower values in both MHT groups compared to placebo. Increases in numbers of tissue factor positive and platelet-derived MV were significantly greater in the transdermal compared to placebo group. MHT was associated with significantly reduced platelet content of vasoactive and mitogenic factors representing a potential mechanism by which MHT may affect vascular remodeling. Various hormonal compositions and doses of MHT could differentially regulate nuclear transcription in bone marrow megakaryocytes and non-genomic pathways in circulating platelets thus determining numbers and characteristics of circulating MV. Thrombotic risk associated with oral MHT most likely involves liver-derived inflammatory/coagulation proteins rather than circulating platelets per se.

Diabetic foot ulcers: evaluation and management

Diabetic foot ulcers (DFUs) are a common complication of diabetes and present a significant health risk to patients, as well as impose a large economic burden. Evaluation for contributory factors that may impact general health or healing, such as hyperglycemia, peripheral artery disease, neuropathy, and nutritional status, is of the utmost importance. Management of DFUs requires involvement of a multidisciplinary team and a standardized approach to patient care. Standard therapy for DFUs includes offloading and debridement. Assessment and control of infection are critical, including determining the severity of the infection, which may drive therapeutic approaches. For recalcitrant ulcers, adjuvant therapies are used to hasten the healing process, and newer therapies are under investigation.

Angiotensin II facilitates fibrogenic effect of TGF-β1 through enhancing the down-regulation of BAMBI caused by LPS: a new pro-fibrotic mechanism of angiotensin II

Angiotensin II has progressively been considered to play an important role in the development of liver fibrosis, although the mechanism isn't fully understood. The aim of this study was to investigate a possible pro-fibrotic mechanism, by which angiotensin II would enhance the pro-fibrotic effect of transforming growth factor beta 1 (TGF-β1) through up-regulation of toll-like receptor 4 (TLR4) and enhancing down-regulation of TGF-β1 inhibitory pseudo-receptor-BAMBI caused by LPS in hepatic stellate cells (HSCs). Firstly, the synergistic effects of angiotensin II, TGF-β1 and LPS on collagen 1α production were confirmed in vitro by ELISA, in which angiotensin II, LPS and TGF-β1 were treated sequentially, and in vivo by immunofluorescence, in the experiments single or multiple intra-peritoneally implanted osmotic mini-pumps administrating angiotensin II or LPS combined with intra-peritoneal injections of TGF-β1 were used. We also found that only LPS and TGF-β1 weren't enough to induce obvious fibrogenesis without angiotensin II. Secondly, to identify the reason of why angiotensin II is so important, the minute level of TLR4 in activated HSCs - T6 and primary quiescent HSCs of rat, up-regulation of TLR4 by angiotensin II and blockage by different angiotensin II receptor type 1 (AT1) blockers in HSCs were assayed by western blotting in vitro and immunofluorescence in vivo. Finally, BAMBI expression level, which is regulated by LPS-TLR4 pathway, was detected by qRT-PCR and results showed angiotensin II enhanced the down-regulation of BAMBI mRNA caused by LPS in vitro and in vivo, and TLR4 neutralization antibody blocked this interactive effect. These data demonstrated that angiotensin II enhances LPS-TLR4 pathway signaling and further down-regulates expression of BAMBI through up-regulation of TLR4, which results in facilitation of pro-fibrotic activity of TGF-β1. Angiotensin II, LPS and TGF-β1 act synergistically during hepatic fibrogenesis, showing crosstalks between angiotensin II-AT1, LPS-TLR4 and TGF-β1-BAMBI signal pathways in rat HSCs.

The Process and Development Mechanism of Age-related Fibrosis in the Pancreatic Islets of Sprague-Dawley Rats: Immunohistochemical Detection of Myofibroblasts and Suppression Effect by Estrogen Treatment

The mechanism of spontaneous islet fibrosis in Sprague-Dawley rats was investigated. Using sections of the pancreas in naive males aged 26 to 102 weeks old and 26-week-old males injected with β-estradiol 3-benzoate (EB), the incidence of lesions and histological scores of fibrosis were examined in conjunction with immunohistochemistry for α-smooth muscle actin (α-SMA), platelet-derived growth factor receptor-α (PDGFRα) and estrogen receptor-α (ERα). The incidence of islet fibrosis increased in 78-week-old animals compared to the 26-week-old animals, and the incidence of atrophy in the fibrotic islet increased in animals over 52 weeks old. α-SMA and PDGFRα were positively stained mainly in fibrotic/inflammatory islets, and the histological score of α-SMA in the fibrotic islet decreased age-dependently. Notably, α-SMA and PDGFRα were co-expressed in inflammatory islets with a high score at all ages. The positive index of ERα in the EB-treated group increased when compared with that of the naive group. However, it was independent of the existence of fibrosis. In contrast, the score of α-SMA and PDGFRα decreased in the EB-treated group. In conclusion, it was clarified that a part of age-related fibrosis in islets became atrophy with age, and α-SMA-positive myofibroblasts were considered to contribute to the development of fibrosis. Strong PDGFRα stainability in fibrotic/inflammatory islets may imply that myofibroblasts were stimulated by PDGF to produce an extracellular matrix. Although estradiol has been known to suppress fibrosis/inflammation in the islet, nuclear-located ER-dependent signaling was considered not to be involved in the suppression mechanism. EB possibly affected the inhibition of the appearance of myofibroblasts.

Cytokines, platelet production and hemostasis

A number of hematopoietic growth factors and other cytokines are capable of altering platelet production and function. Enhancement of these processes may be exploited to ameliorate bleeding propensity in thrombocytopenic patients. Under certain circumstances, cytokines may have adverse effects on the hemostatic system, potentially involved in thrombogenesis and atherogenesis. Inhibition of those cytokines may prove to be a useful experimental approach to investigate their potential pathophysiologic role.

Oxidant signaling for interleukin-13 gene expression in lung smooth muscle cells

The growth of airway and vascular smooth muscle cells occurs in various lung diseases including asthma, chronic obstructive pulmonary disease, bronchopulmonary dysplasia, lymphangioleiomyomatosis, and pulmonary hypertension. Although inflammatory responses are critical in these diseases, the relationship between smooth muscle cell growth and inflammatory mediators is poorly understood. This study demonstrates that platelet-derived growth factor (PDGF) promotes the expression of interleukin-13 (IL-13) in lung smooth muscle cells through an oxidant signaling mechanism. Treatment of cultured human airway or pulmonary vascular smooth muscle cells with PDGF promotes IL-13 mRNA and protein expression. IL-13 expression is also detected in smooth muscle of airways and pulmonary vessels in allergen-stimulated mice. PDGF activates the proximal 980-bp region of the IL-13 promoter. PDGF-induced IL-13 expression is suppressed by the inhibition of reactive oxygen species signaling such as by NAD(P)H oxidase inhibition, reactive oxygen species scavenging, and metal chelation. Treatment of cells with hydrogen peroxide at as low as 1 μM also promotes IL-13 gene expression. PDGF-induced cell growth is suppressed by the neutralizing antibody against IL-13 as well as by reactive oxygen inhibitors, and recombinant IL-13 promotes the growth of airway smooth muscle cells. These results demonstrate that oxidant signaling activates IL-13 gene transcription in lung smooth muscle cells and that this signaling mechanism regulates cell growth.

Platelet gel in the treatment of severe scleroderma skin ulcers

Systemic sclerosis (SSc) is characterized by microvascular damage and fibrosis of the skin and internal organs. Non-healing skin ulcers, mainly non-venous leg ulcers, represent one of the most challenging complications. Platelet gel (PG) is a hemocomponent containing numerous growth factors, potentially useful for tissue reparation. This pilot open study aimed to evaluate the effect of PG in 12 SSc patients with skin ulcers resistant to conventional therapies from at least 6 months. PG was applied in the wound bed twice weekly for 2 weeks, then once a week for 12 weeks; in all cases, the ongoing treatments remained unchanged at the time of PG applications. Skin ulcers were evaluated at 0, 12 and 24 weeks; the patient's quality of life was also evaluated using the visual analogical scale (VAS) and the health assessment questionnaire (HAQ). During the 6-month follow-up, the skin ulcers consistently improved in 10/12 patients, with complete healing in 4. At the last evaluation, wound size reduced from 23.4 ± 14.9 SD to 2.3 ± 2.2 SD cm(2) (p < 0.0001). Patient's quality of life markedly improved: VAS decreased from 87.08 ± 13.5 to 57.9 ± 12.6; p < 0.0001 and HAQ from 0.73 ± 0.43 to 0.57 ± 0.22; p < 0.0001. PG may represent a novel therapeutic option for SSc skin ulcers refractory to conventional treatments.

Lentiviral-Mediated shRNA Silencing of PDE4D Gene Inhibits Platelet-Derived Growth Factor-Induced Proliferation and Migration of Rat Aortic Smooth Muscle Cells

Phosphodiesterase 4D (PDE4D) is a member of the large superfamily of phosphodiesterases. PDE4D polymorphisms have been found to associate with ischemic stroke. Proliferation and migration of vascular smooth muscle cells (VSMCs) play a critical role in the pathogenesis of atherosclerosis. In this study, infection of VSMCs with lentivrius particles carrying shRNA direct against PDE4D significantly inhibited platelet-derived growth factor-induced VSMC proliferation and migration, and the inhibitory effects were not associated with global intracellular cAMP level. Our results implicate that PDE4D has an important role in VSMC proliferation and migration which may explain its genetic susceptibility to ischemic stroke.

Novel use of platelet-rich plasma to augment curative diabetic foot surgery

Autologous platelet-rich plasma (PRP) may enhance wound healing through the formation of a platelet plug that provides both hemostasis and the secretion of biologically active proteins, including growth factors such as platelet-derived growth factor, transforming growth factor (TGF)-β, TGF-β2, and epidermal growth factor. The release of these growth factors into the wound may create an environment more conducive to tissue repair and could accelerate postoperative wound healing. To our knowledge, there are no reports of combining the use of PRP with curative diabetic foot surgery. This article provides a summary of the literature regarding PRP and wound healing and presents a case of a 49-year-old man with diabetes and a three-month history of a deep, nonhealing plantar hallux wound in which PRP was combined with a first metatarsophalangeal joint arthroplasty. Through the use of the PRP and bioengineered tissue to supplement curative diabetic foot surgery, the patient healed uneventfully at seven weeks.

p90 Ribosomal S6 kinase 2, a novel GPCR kinase, is required for growth factor-mediated attenuation of GPCR signaling

The 5-hydroxytryptamine 2A (5-HT(2A)) receptor is a member of the G protein-coupled receptor superfamily (GPCR) and plays a key role in transducing a variety of cellular signals elicited by serotonin (5-HT; 5-hydroxytryptamine) in both peripheral and central tissues. Recently, we discovered that the ERK/MAPK effector p90 ribosomal S6 kinase 2 (RSK2) phosphorylates the 5-HT(2A) receptor and attenuates 5-HT(2A) receptor signaling. This raised the intriguing possibility of a regulatory paradigm whereby receptor tyrosine kinases (RTKs) attenuate GPCR signaling (i.e., "inhibitory cross-talk") by activating RSK2 [Strachan et al. (2009) J. Biol. Chem. 284, 5557-5573]. We report here that activation of multiple endogenous RTKs such as the epidermal growth factor receptor (EGFR), the platelet-derived growth factor receptor (PDGFR), and ErbB4 significantly attenuates 5-HT(2A) receptor signaling in a variety of cell types including mouse embryonic fibroblasts (MEFs), mouse vascular smooth muscle cells (mVSMCs), and primary cortical neurons. Importantly, genetic deletion of RSK2 completely prevented signal attenuation, thereby suggesting that RSK2 is a critical mediator of inhibitory cross-talk between RTKs and 5-HT(2A) receptors. We also discovered that P2Y purinergic receptor signaling was similarly attenuated following EGFR activation. By directly testing multiple endogenous growth factors/RTK pathways and multiple Gq-coupled GPCRs, we have now established a cellular mechanism whereby RTK signaling cascades act via RSK2 to attenuate GPCR signaling. Given the pervasiveness of growth factor signaling, this novel regulatory mechanism has the potential to explain how 5-HT(2A) receptors are regulated in vivo, with potential implications for human diseases in which 5-HT(2A) or RTK activity is altered (e.g., neuropsychiatric and neurodevelopmental disorders).

Chronic inflammation and asthma

Allergic asthma is a complex and chronic inflammatory disorder which is associated with airway hyper-responsiveness and tissue remodelling of the airway structure. Although originally thought to be a Th2-driven inflammatory response to inhaled innocuous allergen, the immune response in asthma is now considered highly heterogeneous. There are now various in vivo systems which have been designed to examine the pathways leading to the development of this chronic immune response and reflect, in part this heterogeneity. Furthermore, the emergence of endogenous immunoregulatory pathways and active pro-resolving mediators hold great potential for future therapeutic intervention. In this review, the key cellular and molecular mediators relating to chronic allergic airway disease are discussed, as well as emerging players in the regulation of chronic allergic inflammation.

Role of platelet-derived growth factor in airway remodeling in rhinosinusitis

BACKGROUND

The purpose of this study was to elucidate the role of platelet-derived growth factor (PDGF) in the pathogenesis of rhinosinusitis.

METHODS

Nasal mucosa and polyps were obtained during surgery in patients with allergic rhinitis, chronic rhinosinusitis (CRS) without asthma, and CRS with asthma. PDGF concentrations in nasal discharge were measured, and the histological distribution and expression levels of mRNA for PDGF and PDGF receptors were examined. PDGF-producing cells were determined by double-staining for PDGF and CD68 or major basic protein.

RESULTS

The concentration of PDGF was significantly higher in CRS with asthma. An immunohistochemical study showed that PDGF was localized in epithelial cells, gland cells, vascular endothelial cells, and inflammatory cells. Expression of PDGF increased in epithelial cells in all three diseases, in macrophages in CRS without asthma, and eosinophils in CRS with asthma, and PDGF receptors were detected in epithelial cells and submucosal fibroblasts. Increased expression of PDGF mRNA was found in CRS with asthma.

CONCLUSION

The results indicate that PDGF is produced by macrophages, eosinophils, and epithelial cells in rhinosinusitis and that it acts on receptors in epithelial cells and fibroblasts. PGDF may be an important cytokine in the pathogenesis of rhinosinusitis by promoting tissue fibrosis and formation of nasal polyps.

The use of platelet-rich plasma in bone reconstruction therapy

The use of platelet-rich plasma (PRP) in bone reconstruction therapy was introduced in the late 1990s. Since then, many scientists and clinicians have employed it in orthopaedic and oral surgeries. Unfortunately, studies that analyze the use of PRP are somewhat controversial as some conclude that the use of PRP may favor bone regeneration and others conclude that the use of PRP is irrelevant. By listing and analyzing the biological effect that each factor released by the activated platelets can have in bone regeneration, the present review answers the question of why PRP may be useful in bone reconstruction therapy. Subsequently, by examining the studies that have both successfully and unsuccessfully utilized PRP, it suggests how PRP might be used in order to achieve successful results in orthopaedic and dental bone reconstruction surgeries.

Current thoughts on angiogenesis

Research into the distinct phases of the process of angiogenesis has informed the development of growth factor therapy and tissue-engineered products, but more studies are needed to ensure the development of new therapeutic strategies.

bFGF rescues imatinib/STI571-induced apoptosis of sis-NIH3T3 fibroblasts

PDGF-B-transfected, sis-NIH3T3 fibroblasts serve as a model system for examining the role of PDGF signaling in tumors. We have found that imatinib/STI571, a tyrosine kinase inhibitor targeting PDGF receptors, induces apoptosis of sis-NIH3T3 fibroblasts cultured under serum free conditions, which was rescued by the addition of 10% newborn calf serum (NCS). Therefore, growth factors included in serum were tested with regard to their ability to rescue imatinib-induced apoptosis. While PDGF-AB, EGF, and IGF-I failed to protect imatinib-induced sis-NIH3T3 cell apoptosis, bFGF rescued it. The effects of bFGF were confirmed by both cell viability assays and Bax/Bcl-2 gene expression ratio. An FGF receptor inhibitor, PD166866, invalidated the protective effect of bFGF. However, combination of imatinib and PD166866 failed to induce cell death of sis-NIH3T3 cells when cultured in 10% NCS. These results indicate that synergistic administration of some types of tyrosine kinase inhibitors need to be tested under in vivo-like conditions to establish novel strategies in anti-cancer therapy.

Suppression of mesangial cell proliferation and extracellular matrix production in streptozotocin-induced diabetic rats by Sp1 decoy oligodeoxynucleotide in vitro and in vivo

Transcription factor Sp-1 is an important fibrogenic factor that is involved in the pathogenesis of diabetic nephropathy. In this study, we examined the effect of Sp1 decoy oligodeoxynucleotides (ODNs) on the extracellular matrix (ECM) gene expression in cultured rat mesangial cells (RMC) and streptozotocin (STZ)-induced diabetic rats. The ring-type Sp1 decoy ODNs significantly decreased ECM mRNA expression and Sp1 binding to the promoter region of these PDGF-induced genes in RMC. In addition, the decoy ODNs was introduced into the left renal artery of diabetic rat using the hemagglutinating virus of Japan (HVJ)-liposome mediated gene transfer method and effectively delivered to the kidney. On 14 days after ring-type Sp1 decoy ODNs injection, type IV collagen, fibronectin mRNA, and protein expression were markedly decreased, and the rate of urinary creatinine excretion was reduced in the ring-type Sp1 decoy ODNs-treated diabetic rats. These results indicated that the ring-type Sp1 decoy ODNs would be superior to P-Sp1 ODNs. Also, the R-Sp1 decoy ODN when introduced in vivo, effectively reduced ECM production during the progression of nephropathy. Therefore, ring-type Sp1 decoy is a promising tool for developing new therapeutic applications for progressive diabetic nephropathy.

Retinoic acid fails to reverse oligohydramnios-induced pulmonary hypoplasia in fetal rats

All-trans retinoic acid (ATRA) stimulates platelet-derived growth factor (PDGF)-A expression and enhances alveolarization in rat lungs. On d 16 of gestation, pregnant Sprague-Dawley rats were randomly assigned to either a retinoic acid group (intragastric ATRA at 10 mg/kg body weight) or a vehicle group. We punctured each amniotic sac, and fetuses in the opposite uterine horn served as controls. On d 21 of gestation, the fetuses were delivered by cesarean section. Rats subjected to oligohydramnios exhibited significantly lower lung weights and lung/body weight ratios, and ATRA had no effects on the body or lung weights of oligohydramnios-exposed rats. Lung PDGF-A and -B mRNA expression was significantly lower in oligohydramnios-exposed rats compared with control littermates of maternal vehicle-treated dams. Maternal retinoic acid treatment significantly increased PDGF-A and -B mRNA expression in control and oligohydramnios-exposed rats compared with all rats and oligohydramnios-exposed rats of maternal vehicle-treated dams, respectively. Rats exposed to oligohydramnios exhibited a significantly lower generation of alveolar saccules than did control rats in the maternal retinoic acid- and vehicle-treated groups. In this model, maternal retinoic acid treatment showed no positive effects on oligohydramnios-induced pulmonary hypoplasia in the pseudoglandular stage.

TGF-beta 1 and fibroblast growth factors selectively up-regulate tissue-specific fetal genes in cardiac muscle cells

TGF-beta 1, like basic and acidic fibroblast growth factor (FGF), inhibits differentiated gene expression in skeletal myoblasts. It potentiates FGF-beta 1 down-regulated expression of the alpha-myosin heavy chain gene and the sarcoplasmic reticulum calcium ATPase gene, yet up-regulated expression of the genes for beta-myosin heavy chain, atrial natriuretic factor, and both skeletal and smooth muscle alpha-actin-four transcripts associated with the embryonic heart. TGF-beta 1 did not affect cardiac alpha-actin gene expression. These responses resemble the generalized 'fetal' phenotype seen during hypertrophy triggered by a haemodynamic load. Chick skeletal and cardiac alpha-actin promoter-driven reported genes were transfected into neonatal rat cardiac myocytes. TGF-beta 1 stimulated skeletal alpha-actin transcription, but not transcription from the cardiac alpha-actin promoter. Basic FGF produced the same results as TGF-beta 1, but acidic FGF suppressed expression of both alpha-actin genes; these results were true for purified and recombinant FGFs. Modulation of alpha-actin transcription by growth factors corresponded accurately to control of the endogenous genes. Three positive cis-acting elements were critical for skeletal alpha-actin transcription in cardiac, as well as skeletal, myocytes, particularly the downstream CCAAT box-associated repeat. Thus, TGF-beta 1 and FGFs selectively induce an ensemble of 'fetal' genes and differentially regulate alpha-actin transcription in cardiac muscle cells.

Growth factors in the treatment of diabetic foot ulcers: new technologies, any promises?

Foot ulcers remain a common problem, leading to increased morbidity in patients with diabetes. Despite the progress that has been achieved in revascularization techniques as well as in off-loading to relieve high-pressure areas, diabetic foot wounds remain a clinical challenge. Growth factors are a major technological advance that promised to change the face of wound healing. The most important of growth factors are recombinant human platelet-derived growth factor-BB and granulocyte colony-stimulating factor. The former has been approved by the FDA for the treatment of neuropathic ulcers when there is adequate blood supply. The latter is less demonstrably useful. Advances include methods of delivering growth factors.

Oligohydramnios decreases platelet-derived growth factor expression in fetal rat lungs

OBJECTIVE

To evaluate the effects of experimental oligohydramnios on lung growth, expression of platelet-derived growth factor (PDGF) and its receptors, and lung morphology in fetal rats.

METHODS

On day 16 of gestation, we anesthetized timed pregnant Sprague-Dawley dams and punctured uterine wall and fetal membranes of each uterine sac which resulted in oligohydramnios. The fetuses in the opposite uterine horn served as controls. On days 19 and 21 of gestation, the fetuses were delivered by cesarean section and weighed, and the lungs were dissected free and weighed.

RESULTS

Rats exposed to oligohydramnios exhibited significantly lower lung/body weight ratios on days 19 and 21 of gestation and significantly lower radial saccular counts on day 21 of gestation than did the control rats. Lung PDGF-A and PDGF-B gene and protein expression and elastin level were significantly decreased in rats exposed to oligohydramnios on days 19 and 21 of gestation. The PDGF receptor alpha and beta gene expression levels were significantly decreased in rats exposed to oligohydramnios on day 19 of gestation.

CONCLUSION

A decreased PDGF expression may be important in the pathogenesis of oligohydramnios-induced pulmonary hypoplasia and suggests that supplementation may provide useful therapeutic strategies.

Influence of autologous platelet concentrate on healing in intra-bony defects following guided tissue regeneration therapy: a randomized prospective clinical split-mouth study

OBJECTIVES

To investigate the influence of autologous platelet concentrate (APC) on early wound healing and regeneration outcomes following guided tissue regeneration (GTR) therapy.

MATERIAL AND METHODS

In 25 patients, two contralateral deep intra-bony defects were treated with beta-TCP and a bioresorbable GTR membrane. They were randomly assigned to test and control procedure. In test defects, APC was additionally applied. After 3, 6, and 12 months, healing results were assessed by clinical parameters and quantitative digital subtraction radiography.

RESULTS

Post-operative membrane exposures occurred in 48% of the test sites and 80% of the control sites. Both groups revealed a significant clinical attachment level (CAL) gain of 5 mm after 12 months. Eighty-eight per cent of test and control sites showed a CAL gain of > or =4 mm. No clinical parameter revealed significant differences between test and control sites. A significant bone density gain was found in both groups after 3, 6, and 12 months. Only after 6 months, the bone density gain was significantly greater in the test defects.

CONCLUSION

Within the limits of this study, autologous platelet concentrate did not seem to have a noticeable influence on the clinical and most of the radiographic outcomes following GTR. However, APC might reduce the occurrence of post-operative membrane exposures and accelerate bone density gain.

Overexpression of redox-active protein thioredoxin-1 prevents development of chronic pancreatitis in mice

Chronic pancreatitis (CP) is considered to result from repetitive pancreatic injury, and sustained production of various proinflammatory cytokines and chemokines are closely involved in its pathogenesis. Monocyte chemoattractant protein 1 (MCP-1), a member of the CC chemokine family, is believed to contribute to the progression of CP through monocyte/macrophage recruitment. This study aimed to clarify the protective role of thioredoxin-1 (TRX-1), a redox-regulating protein with antioxidative activity, in MCP-1 production and pancreatic fibrosis using a CP model in transgenic mice overexpressing TRX-1 (TRX-1-TG mice) and wildtype C57BL/6 mice. Experimental CP was induced by repeated administration of cerulein and lipopolysaccharide for 6 weeks. In TRX-1-TG mice, pancreatic atrophy was ameliorated, and histologically detectable inflammatory cell infiltration, glandular atrophy, and pseudotubular complex formation were suppressed. Overexpression of TRX-1 also attenuated pancreatic fibrosis and suppressed the activation of pancreatic stellate cells. Serum levels of MCP-1 and pancreatic expression of transforming growth factor-beta, platelet-derived growth factor, and MCP-1 were reduced in TRX-1-TG mice compared with levels in wild-type mice. Overexpression of TRX-1 also reduced H(2)O(2)-induced MCP-1 production in isolated pancreatic acinar cells. These results indicate that TRX-1 can potentially attenuate pancreatic fibrosis via the suppression of oxidative stress and MCP-1-mediated chronic inflammation.

Clinical evaluation of recombinant human platelet-derived growth factor for the treatment of lower extremity ulcers

BACKGROUND

Diabetic foot ulcer is a major health care problem that leads to amputation.

METHODS

Patients with full-thickness diabetic neurotrophic foot ulcers present for longer than 8 weeks without healing were entered into one of five randomized, prospective, blinded clinical trials comparing treatment with platelet-derived growth factor (PDGF) or placebo gel for up to 20 weeks. The purpose of these trials was to assess the safety and efficacy of PDGF used with good wound care. Each patient had an adequate arterial blood supply, was free of infection, was off-loaded, and was extensively débrided. The ulcers had been present for at least 8 weeks.

RESULTS

A total of 922 patients were entered into the study. Analysis of ulcers with a baseline area of less than 10 cm (95 percent of patients) showed that patients treated with PDGF at 100 mug/g had a significant increase in complete healing compared with patients given placebo (50 percent versus 36 percent, p < 0.007). PDGF also decreased the time to complete healing by 30 percent (14 weeks versus 20 weeks, p = 0.01). Adverse events were similar in both treatment groups, as were recurrent ulcer rates.

CONCLUSION

PDGF applied once daily was effective in healing chronic diabetic neurotrophic foot ulcers when used in conjunction with good wound care.

Advances in the management of leg ulcers--the potential role of growth factors

Venous ulcers are a major health problem because of the increased costs of the treatment and the refractory nature of the ulcers. The treatment cost is estimated to be around 1 billion dollars per year in the United States (US), and the average cost for one patient over a lifetime exceeds dollars 400,000. There has been an increasing trend in the use of growth factors in their management. Genetic engineering has revolutionised the research of wound healing, as the majority of recombinant growth factors are now available for in vitro and in vivo studies. Online searches of Medline, Pub Medical and Embase were carried out using the terms venous ulcers, leg ulcers, growth factors and growth hormone. The literature regarding the potential role of growth factors in the management of leg ulcers is reviewed. The important clinical studies are critically analysed with a view to appreciate the emerging therapies and the further research possibilities in the management of venous leg ulcers. Clinical results with the use of growth factors in non-healing wounds are encouraging. However, small sample sizes and inconsistent end points in different clinical studies have been the main hurdle in reaching a definite conclusion. Further research is needed to provide the definite evidence. Future developments may include different delivery methods for the growth factors, use of different combinations of growth factors administered simultaneously or, sequentially, bioengineered skin grafts and chemical induction of angiogenesis with the use of gene transfer techniques.

Signal transduction mechanisms of K+-Cl- cotransport regulation and relationship to disease

The K+-Cl- cotransport (COT) regulatory pathways recently uncovered in our laboratory and their implication in disease state are reviewed. Three mechanisms of K+-Cl- COT regulation can be identified in vascular cells: (1) the Li+-sensitive pathway, (2) the platelet-derived growth factor (PDGF)-sensitive pathway and (3) the nitric oxide (NO)-dependent pathway. Ion fluxes, Western blotting, semi-quantitative RT-PCR, immunofluorescence and confocal microscopy were used. Li+, used in the treatment of manic depression, stimulates volume-sensitive K+-Cl- COT of low K+ sheep red blood cells at cellular concentrations <1 mM and inhibits at >3 mM, causes cell swelling, and appears to regulate K+-Cl- COT through a protein kinase C-dependent pathway. PDGF, a potent serum mitogen for vascular smooth muscle cells (VSMCs), regulates membrane transport and is involved in atherosclerosis. PDGF stimulates VSM K+-Cl- COT in a time- and concentration-dependent manner, both acutely and chronically, through the PDGF receptor. The acute effect occurs at the post-translational level whereas the chronic effect may involve regulation through gene expression. Regulation by PDGF involves the signalling molecules phosphoinositides 3-kinase and protein phosphatase-1. Finally, the NO/cGMP/protein kinase G pathway, involved in vasodilation and hence cardiovascular disease, regulates K+-Cl- COT in VSMCs at the mRNA expression and transport levels. A complex and diverse array of mechanisms and effectors regulate K+-Cl- COT and thus cell volume homeostasis, setting the stage for abnormalities at the genetic and/or regulatory level thus effecting or being affected by various pathological conditions.

The plateled-derived growth factor level (PDGF) in Hodgkin's disease and non-Hodgkin's lymphoma and its relationship disease activation

The research reported in this paper was designed to study the role of plateled-derived growth factor (PDGF) in Hodgkin's disease (HD) and non-Hodgkin's lymphomas (NHL). The PDGF levels in 9 patients with HD and 12 NHL and in a control group consisting of 20 people, was measured by ELISA method. The PDGF values in the disease group of 19 patients were raised. The values of PDGF in the control group were 28.977+/-9 pg/ml, but were measured at 147.083+/-54 pg/ml in HD group and 131.487+/-56 pg/ml in NHL group (p < 0.01). The observation of a 5-fold increase in PDGF values in the disease group when compared to the control group suggests that PDGF could itself be considered as a possible factor in the pathogenesis of HD and NHL. In order to support this, there is a need to design additional studies monitoring PDGF in larger number of patients at various stages of the disease.

Activation of JAK-STAT pathway is required for platelet-derived growth factor-induced proliferation of pancreatic stellate cells

AIM: To clarify the role of Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway in platelet-derived growth factor (PDGF) induced proliferation in activated pancreatic stellate cells (PSCs).

METHODS: PSCs were isolated from rat pancreas tissue, and used in their culture-activated, myofibroblast-like phenotype. STAT-specific binding activity was assessed by electrophoretic mobility shift assay. Activation of Src, JAK2, STAT1, STAT3, and ERK was determined by Western blotting using anti-phosphospecific antibodies. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2’-deoxyuridine.

RESULTS: PDGF-BB induced STAT-specific binding activity, and activation of Src, JAK2, STAT1, STAT3, and ERK. Ethanol and acetaldehyde at clinically relevant concentrations decreased basal activation of JAK2 and STAT3. PDGF-induced activation of STAT1 and STAT3 was inhibited by a Src inhibitor PP1 and a JAK2 inhibitor AG490, whereas PDGF-induced activation of ERK was inhibited by PP1, and not by AG490. PDGF-induced proliferation was inhibited by PP1 and AG490 as well as by STAT3 antisense oligonucleotide.

CONCLUSION: PDGF-BB activated JAK2-STAT pathway via Src-dependent mechanism. Activation of JAK2-STAT3 pathway, in addition to ERK, may play a role in PDGF-induced proliferation of PSCs.

Green tea polyphenol epigallocatechin-3-gallate blocks PDGF-induced proliferation and migration of rat pancreatic stellate cells

AIM: To clarify the effects of epigallocatechin-3-gallate (EGCG) on the platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of pancreatic stellate cells (PSCs).

METHODS: PSCs were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2’-deoxyuridine. Cell migration was assessed using modified Boyden chambers. Cyclin D1, p21^Waf1, and p27^Kip1 expression and phosphorylation of PDGF β-receptor, extracellular signal-regulated kinase, and Akt were examined by Western blotting. Activation of phospha-tidylinositol 3-kinase was examined by kinase assay using phosphatidylinositol as a substrate. Cell cycle was assessed by flow cytometry after staining with propidium iodide.

RESULTS: EGCG at non-cytotoxic concentrations inhibited PDGF-induced proliferation and migration. This effect was associated with the inhibition of cell cycle progression beyond the G₁ phase, decreased cyclin D1 and increased p27^Kip1 expression. EGCG inhibited tyrosine phosphorylation of PDGF β-receptor and downstream activation of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase/Akt pathways.

CONCLUSION: EGCG inhibited PDGF-BB-induced proliferation and migration of PSCs through the inhibition of PDGF-mediated signaling pathways.

Effect of human platelet supernatant on proliferation and matrix synthesis of human articular chondrocytes in monolayer and three-dimensional alginate cultures

Articular cartilage is rich in collagen type II fibres and proteoglycans and is characterized by low cell density. Chondrocytes have specific nutritional requirements and therefore cannot be expanded in vitro without the risk of generating fibroblastoid cells expressing type I collagen. Therefore, various growth conditions were tested for cartilage tissue engineering. Human platelets are a rich source of many growth factors including transforming growth factor-beta and platelet-derived growth factor. To investigate the effect of human platelet supernatant (hPS) on chondrocyte proliferation and differentiation, human articular biopsies obtained from three healthy donors. Chondrocytes were isolated and expanded separately in monolayer cultures and seeded in alginate beads in the presence and absence of hPS of 1% or 10% v/v concentration. Transcript levels of genes encoding chondrogenic factors were determined by quantitative reverse transcriptase-polymerase chain reaction. The deposition of types I and II collagen as well as proteoglycan was detected by indirect immunocytochemistry. Addition of hPS activated chondrocyte proliferation in monolayer cultures but induced a dedifferentiation of chondrocytes towards a fibroblast-like phenotype. The expression levels of mRNAs encoding type II collagen, aggrecan and bone morphogenetic protein-2 were reduced in all samples tested. Seeding chondrocytes in alginate beads in the presence of hPS generated a cell population capable of type II collagen expression, even though hPS induced considerable type I collagen expression as well. Differences (1% vs. 10% group, 1% vs. control, 10% vs. control) in the quantitative gene expression of types I and II collagen or of aggrecan were statistically significant (p<0.001). We conclude that addition of hPS may accelerate chondrocyte expansion but can lead to their dedifferentiation.

Agents in development for the treatment of diabetic nephropathy

Diabetic nephropathy is a leading cause of end-stage renal disease, and accounts for significant morbidity and mortality in patients with diabetes. Diabetic nephropathy seems to occur as a result of an interaction between metabolic and haemodynamic factors, which activate common pathways that lead to renal damage. In the past, the treatment of diabetic nephropathy has focused on the control of hyperglycaemia. Newer targets, some of which are linked to glucose-dependent pathways, appear to be a major focus of new treatments directed against the development and progression of renal damage as a result of diabetes. It is anticipated that additional therapeutic approaches that inhibit both metabolic and haemodynamic pathways will include strategies that target growth factors, cytokines and intracellular second messengers. Such an approach is expected to lead to improved therapies for the treatment of diabetic nephropathy.