Leptin and the skin: a new frontier

Measurement of the levels of leptin, BDNF associated with polymorphisms LEP G2548A, LEPR Gln223Arg and BDNF Val66Met in Thai with metabolic syndrome

BACKGROUND

Metabolic syndrome is a cluster of metabolic risk factors including dyslipidemia, impaired glucose tolerance, hypertension and central obesity. BDNF (Brain-derived neurotrophic factor) and leptin have been implied in the energy homeostasis. The purposes of this study were to examine concentrations of leptin, BDNF and biochemical parameters in metabolic-syndrome subjects and healthy controls, and also to search for associations of leptin gene (LEP) G2548A, leptin receptor gene (LEPR) Gln223Arg, and BDNF gene (BDNF) Val66Met polymorphisms with leptin levels, BDNF levels and metabolic syndrome among Thais.

METHODS

The case-controlled design was performed using 322 Thai volunteers (160 metabolic-syndrome subjects; 162 controls) during the health screening program. Metabolic syndrome was assessed by using the modified National Cholesterol Education Program, Adult Treatment Panel III criteria. The levels of leptin, BDNF, insulin, glucose and lipids were measured in samples. Genotyping of LEP G2548A, LEPR Gln223Arg and BDNF Val66Met was carried out using polymerase chain reaction-restriction fragment length polymorphism technique.

RESULTS

Serum leptin levels were significantly higher in the metabolic-syndrome group than the control group (p < 0.01), but the BDNF difference between them was not significant. Significant associations of LEPR Gln223Arg polymorphism were found with leptin and glucose levels (p < 0.05), after adjusting for potential covariates. This LEPR polymorphism in the metabolic-syndrome group was also significantly more frequent than in the control group (p < 0.05). However, other gene polymorphisms, LEP G2548A and BDNF Val66Met, showed no significant relationship with leptin levels, BDNF levels or metabolic syndrome.

CONCLUSION

These findings suggest leptin levels are linked with metabolic syndrome. LEPR Gln223Arg polymorphism impacted leptin concentrations, and this gene polymorphism may influence susceptibility to metabolic syndrome among Thais.

Associated factors and comorbidities in patients with pyoderma gangrenosum in Germany: a retrospective multicentric analysis in 259 patients

Background

Pyoderma gangrenosum (PG) is a rarely diagnosed ulcerative neutrophilic dermatosis with unknown origin that has been poorly characterized in clinical studies so far. Consequently there have been significant discussions about its associated factors and comorbidities. The aim of our multicenter study was to analyze current data from patients in dermatologic wound care centers in Germany in order to describe associated factors and comorbidities in patients with PG.

Methods

Retrospective clinical investigation of patients with PG from dermatologic wound care centers in Germany.

Results

We received data from 259 patients with PG from 20 different dermatologic wound care centers in Germany. Of these 142 (54.8%) patients were female, 117 (45.2%) were male; with an age range of 21 to 95 years, and a mean of 58 years. In our patient population we found 45.6% with anemia, 44.8% with endocrine diseases, 12.4% with internal malignancies, 9.3% with chronic inflammatory bowel diseases and 4.3% with elevated creatinine levels. Moreover 25.5% of all patients had a diabetes mellitus with some aspects of potential association with the metabolic syndrome.

Conclusions

Our study describes one of the world’s largest populations with PG. Beside the well-known association with chronic bowel diseases and neoplasms, a potentially relevant new aspect is an association with endocrine diseases, in particular the metabolic syndrome, thyroid dysfunctions and renal disorders. Our findings represent clinically relevant new aspects. This may help to describe the patients’ characteristics and help to understand the underlying pathophysiology in these often misdiagnosed patients.

Construction of a recombinant eukaryotic expression vector containing a leptin gene and its expression in HPMSCs

Leptin gene fragments were amplified from human adipose tissue using reverse transcription polymerase chain reaction technology. The leptin gene was reconstructed in pIRES2-EGFP and transfected into human placenta-derived mesenchymal stem cells (HPMSCs) using a liposome-mediated method. Leptin mRNA and protein was detected in the transfected cells using RT-PCR and Western blot analysis, and the results showed that HPMSCs transfected with pIRES2-EGFP-leptin expressed significantly more leptin mRNA and protein than HPMSCs transfected with pIRES2-EGFP. EGFP expression was observed under a fluorescence microscope, and results showed the report gene to have been successfully transferred into the target cells. The biological activity of leptin and the cell proliferation activity of HPMSCs transfected with pIRES2-EGFP-leptin was detected using an MTT assay, which showed that leptin can promote the proliferation of HPMSCs. However, leptin in HPMSCs transfected with pIRES2-EGFP-leptin showed significantly more activity than HPMSCs transfected with pIRES2-EGFP. Identification of multipotency showed that HPMSCs transfected with pIRES2-EGFP-leptin maintained their multipotency.

Characteristics of an autologous leukocyte and platelet-rich fibrin patch intended for the treatment of recalcitrant wounds

We have investigated the physical, biochemical, and cellular properties of an autologous leukocyte and platelet-rich fibrin patch. This was generated in an automated device from a sample of a patient's blood at the point of care. Using microscopy, cell counting, enzyme-linked immunosorbent assay, antibody arrays, and cell culture assays, we show that the patch is a three-layered membrane comprising a fibrin sheet, a layer of platelets, and a layer of leukocytes. Mean recovery of platelets from the donated blood was 98% (±95%CI 0.8%). Mean levels of platelet-derived growth factor AB, human transforming growth factor beta 1, and vascular endothelial growth factor extracted from the patch were determined as 127 ng (±95% CI 20), 92 ng (±95%CI 17), and 1.35 ng (±95%CI 0.37), respectively. We showed a continued release of PDGF-AB over several days, the rate of which was increased by the addition of chronic wound fluid. By comparison with traditional platelet-rich plasma, differences in immune components were found. The relevance of these findings was assessed by showing a mitogenic and migratory effect on cultured human dermal fibroblasts. Further, we showed that fibrocytes, a cell type important for acute wound healing, could be grown from the patch. The relevance of these findings in relation to the use of the patch for treating recalcitrant wounds is discussed.

Expression of leptin and its long-form receptor in the marginal cutaneous tissues of diabetic foot ulcers

To investigate the relationship between the expression of leptin and its long-form receptor, OB-RL, and wound healing in diabetic foot ulcers. Biopsies from 10 patients with diabetic foot ulcers (DU group), 10 with non-diabetic foot ulcers (NDU group), and 10 with normal skin (normal control, NC group) were examined. Leptin and OB-RL mRNA and protein levels were assessed using RT-PCR and immunohistochemistry analyses, respectively. The cuticle thickness was significantly greater, and the epidermal layer was significantly lesser in the DU and NDU groups. Leptin protein expression was significantly higher in the DU and NDU than NC group (P < 0.001), whereas OB-RL mRNA and protein expressions were significantly lower in the DU group and significantly higher in the NDU group (P < 0.001). Diabetic foot ulcer duration was negatively correlated with OB-RL protein expression (ρ = -0.671, P = 0.034). Decreased OB-RL may result in reduced leptin signaling in diabetic foot ulcers. Further studies are required to determine whether OB-RL levels are related to the prognosis of diabetic foot ulcers, as well as to explore the use of leptin or mimetics for promoting ulcer healing.

Green light emitting diodes accelerate wound healing: characterization of the effect and its molecular basis in vitro and in vivo

Because light-emitting diodes (LEDs) are low-coherent, quasimonochromatic, and nonthermal, they are an alternative for low level laser therapy, and have photobiostimulative effects on tissue repair. However, the molecular mechanism(s) are unclear, and potential effects of blue and/or green LEDs on wound healing are still unknown. Here, we investigated the effects of red (638 nm), blue (456 nm), and green (518 nm) LEDs on wound healing. In an in vivo study, wound sizes in the skin of ob/ob mice were significantly decreased on day 7 following exposure to green LEDs, and complete reepithelialization was accelerated by red and green LEDs compared with the control mice. To better understand the molecular mechanism(s) involved, we investigated the effects of LEDs on human fibroblasts in vitro by measuring mRNA and protein levels of cytokines secreted by fibroblasts during the process of wound healing and on the migration of HaCat keratinocytes. The results suggest that some cytokines are significantly increased by exposure to LEDs, especially leptin, IL-8, and VEGF, but only by green LEDs. The migration of HaCat keratinocytes was significantly promoted by red or green LEDs. In conclusion, we demonstrate that green LEDs promote wound healing by inducing migratory and proliferative mediators, which suggests that not only red LEDs but also green LEDs can be a new powerful therapeutic strategy for wound healing.

Risk factors for hypertrophic surgical scar development after thyroidectomy

Postoperative neck scarring is a major concern for patients who undergo thyroid surgery; however, the treatments for hypertrophic scars are generally considered by patients to provide unsatisfactory outcomes. Therefore, risk factors should be identified and prevention of these factors is considered to be critical in management. We reviewed the medical records of 96 thyroidectomy patients who were divided into two groups based on scar type: patients with hypertrophic (n = 61) and linear flat scars (n = 35). Multivariable logistic regression model was developed to identify risk factors for developing hypertrophic scar. There was no significant difference between the two groups in terms of age, gender ratio, tumor type, and type of operation. Multivariable analysis showed that hypertrophic scar development was associated with scars located within 1 cm above the sternal notch (odds ratio [OR] = 5.94, p = 0.01), prominent sternocleidomastoid muscles (OR = 12.03, p < 0.01), and a high body mass index (OR = 1.33, p = 0.01). The area under the receiver operating characteristic curve for risk factors was 0.85. Development of hypertrophic scar after thyroidectomy was found to be associated with specific preoperative factors such as incision site near the sternal notch, prominent sternocleidomastoid muscles, and high body mass index.

Comparative analysis of paracrine factor expression in human adult mesenchymal stem cells derived from bone marrow, adipose, and dermal tissue

Human adult mesenchymal stem cells (MSCs) support the engineering of functional tissue constructs by secreting angiogenic and cytoprotective factors, which act in a paracrine fashion to influence cell survival and vascularization. MSCs have been isolated from many different tissue sources, but little is known about how paracrine factor secretion varies between different MSC populations. We evaluated paracrine factor expression patterns in MSCs isolated from adipose tissue (ASCs), bone marrow (BMSCs), and dermal tissues [dermal sheath cells (DSCs) and dermal papilla cells (DPCs)]. Specifically, mRNA expression analysis identified insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor-D (VEGF-D), and interleukin-8 (IL-8) to be expressed at higher levels in ASCs compared with other MSC populations whereas VEGF-A, angiogenin, basic fibroblast growth factor (bFGF), and nerve growth factor (NGF) were expressed at comparable levels among the MSC populations examined. Analysis of conditioned media (CM) protein confirmed the comparable level of angiogenin and VEGF-A secretion in all MSC populations and showed that DSCs and DPCs produced significantly higher concentrations of leptin. Functional assays examining in vitro angiogenic paracrine activity showed that incubation of endothelial cells in ASC(CM) resulted in increased tubulogenic efficiency compared with that observed in DPC(CM). Using neutralizing antibodies we concluded that VEGF-A and VEGF-D were 2 of the major growth factors secreted by ASCs that supported endothelial tubulogenesis. The variation in paracrine factors of different MSC populations contributes to different levels of angiogenic activity and ASCs maybe preferred over other MSC populations for augmenting therapeutic approaches dependent upon angiogenesis.

Obesity and the skin

Obesity is a serious global health problem, perhaps the biggest public health issue of our times. Excess body weight may be a factor in carcinogenesis in general, as well as contributing to the pathogenesis of metabolic, cardiovascular and musculoskeletal disorders. Obesity also has many cutaneous features, which form the basis for this review article. Many of these clinical entities are common to the majority of obese patients, e.g. striae distensae, plantar hyperkeratosis and an increased risk of skin infections. However, it may also be associated with poor wound healing, malignant melanoma and an increased risk of inflammatory dermatoses, such as psoriasis, as well as some rarer disorders. Therapeutic interventions for obesity, whether over-the-counter, prescription medicines or surgical interventions, are increasingly commonplace. All of these treatment modalities potentially have dermatological side-effects too.

Investigation of new co-factors in 49 patients with pyoderma gangrenosum

BACKGROUND

Pyoderma gangrenosum is a rare, destructive, ulcerative neutrophilic dermatosis of unknown origin that has been investigated insufficiently in clinical studies. According to current textbooks, it is often associated with chronic inflammatory bowel diseases or other autoimmune disorders.

PATIENTS AND METHODS

We retrospectively analyzed data from 49 patients with pyoderma gangrenosum.

RESULTS

Our results showed that although only 6.1 % of patients had chronic inflammatory bowel disease, 22.4 % patients had a malignancy, 18.4 % had chronic renal insufficiency, and 42.8 % had anemia. A potentially relevant aspect that has received little attention is an association with endocrine diseases in 38.8 % of patients. 28.6 % of patients had diabetes. Given that 32.6 % of patients were obese, a potential association with metabolic syndrome may be considered as a possible new risk factor for pyoderma gangrenosum.

CONCLUSIONS

The clinical data from the present study are insufficient for drawing any firm conclusions. We did, however, observe an association between pyoderma gangrenosum and certain as yet unreported co-factors, in particular metabolic syndrome. This should be considered in further studies.

Microdialysis documents changes in the micromilieu of psoriatic plaques under continuous systemic therapy

Microdialysis is a novel technique suitable to analyse soluble mediators in the skin compartment. We applied this methodical approach to monitor changes in the micromilieu of psoriatic plaques under therapy. Tissue fluid was collected from lesional and non-lesional skin of three patients with severe plaque-type psoriasis prior to as well as after 12 weeks of continuous oral therapy with fumaric acid esters. Concentrations of a spectrum of cytokines and adipokines were measured using a commercial fluorescent bead immunoassay. The procedure was well tolerated even without local anaesthesia. Prior to initiation of therapy, we found elevated levels for IL-2, IL-6, IL-18, IL-23, and resistin in lesional versus non-lesional skin, whereas adiponectin levels were higher in non-lesional skin. All patients showed significant clinical improvement under treatment, paralleled by reduced concentrations of IL-6, IL-18, IL-23, and resistin, but not IL-2 and adiponectin in lesional skin. Thus, we were able to demonstrate through microdialysis a shift in the micromilieu of psoriatic plaques, characterized by reduced levels of pro-inflammatory mediators in three patients under effective systemic anti-inflammatory therapy with fumaric acid esters. Our observations need to be confirmed by larger studies. This approach is limited by practical aspects as it is very time-consuming, but suitable to directly explore pathomechanisms causing the psoriatic phenotype in general and insulin resistance in the skin compartment in particular.

Adipokines and psoriasis

Adipose tissue is an active endocrine organ contributing to the regulation of multiple metabolic pathways via self-produced bioactive products called adipokines. These adipokines are key players in the pathogenesis of metabolic syndrome and cardiovascular diseases. Co-occurrence of obesity and psoriasis could lead to interactions of both diseases in which adipokines, at least in part, are involved and may contribute to associated comorbidities of psoriasis. Until today numerous adipokines have been identified of which the most important ones are discussed in the following within the context of obesity, chronic inflammation and their possible role in the pathogenesis of psoriasis. Adipokines could serve as a missing link in the causal relationship between psoriasis and comorbidities and may provide a biomarker for disease severity, risk of comorbidities and treatment success.

Association between the leptin gene 2548G/A polymorphism, the plasma leptin and the metabolic syndrome with psoriasis

BACKGROUND

Psoriasis is a disorder with genetic and immunologic background. Leptin can regulate the T-helper response.

OBJECTIVE

Our primary goal is to study the functional polymorphism (G-2548A) of the leptin (LEP) gene in the genetic predisposition of psoriasis, and our secondary goal is to examine factors affecting plasma leptin levels in psoriasis and to compare patients with and without metabolic syndrome (MS).

METHODS

The study involved 94 patients with psoriasis and 100 healthy controls. Analysis of G-2548A polymorphism of the LEP gene was made by the PCR and restriction fragment length polymorphism technique. The relationship between LEP gene polymorphism and the clinical features of the patients was analysed. Plasma leptin levels and proportions of comorbidities in patients vs controls were compared.

RESULTS

In controls, the GA, AA and GG frequencies were 50%, 30% and 20%, respectively, while in patients, the distribution of genotypes was 42.5%, 20.2% and 38.3%, respectively, with significant difference (P = 0.014) between patients and controls. In patients with MS, the GG, GA and AA frequencies were 61.5%, 23.1% and 15.4%, respectively, while in patients without MS, the distribution of genotypes was 29.4%, 50% and 20.6%, respectively, with significant difference (P = 0.014) between both groups. Plasma leptin showed a significant higher levels in the patients versus the controls (P < 0.001), and among the different LEP genotypes (P < 0.001) in the patients' group.

CONCLUSION

LEP G-2548A polymorphism could be a predictor for higher plasma leptin and increased risk of psoriasis and could be used as a marker for psoriasis-related comorbidity risk.

Adipocyte-brain: crosstalk

The initial discovery of leptin, an appetite-suppressing hormone originating from fat tissue, substantially supported the idea that fat-borne factors act on the brain to regulate food intake and energy expenditure. Since then, a growing number of cytokines have been found to be released from adipose tissue, thus acting in an endocrine manner. These adipocytokines include not only, e.g., adiponectin, apelin, resistin, and visfatin, but also inflammatory cytokines and steroid hormones such as estrogens and glucocorticoids. They are secreted from their adipose depots and differ in terms of release stimuli, downstream signaling, and their action on the brain. Clearly, adipocytokines play a prominent role in the central control of body weight, and the deregulation of this circuit may lead to the development of obesity and related disorders. In this chapter, we will focus on crosstalk mechanisms and the deregulation of adipocytokines at the expression level and/or sites of central action that eventually will lead to the development and perpetuation of obesity and diabetes.

Cutaneous wound healing of chronically stressed mice is improved through catecholamines blockade

Stress impairs cutaneous wound healing; however, it is unclear how beta-adrenoceptors participates in alterations induced by stress on skin wound repair. Therefore, the aim of this study was to investigate the effects of propranolol, a non-selective beta-blocker, administration on cutaneous wound healing of chronically stressed mice. Male mice were spun at 115 rpm for 15 min every hour from three days before wounding until euthanasia. Control animals were not submitted to stress. Stressed and control animals were treated with propranolol dissolved in water; controls received only water. Propranolol administration began one day before wounding and was continued daily until euthanasia. A full-thickness excisional lesion was performed. Seven and fourteen days later, animals were killed, and lesions were formalin-fixed and paraffin-embedded. Sections were stained with hematoxylin-eosin and immunostained against F4/80 to quantify macrophages, alpha-smooth muscle actin to quantify the myofibroblast density and proliferating cell nuclear antigen to quantify the cell proliferation. Furthermore, matrix metalloproteinases (MMP)-2 and MMP-9 activity, nitrite and hydroxyproline levels and tumor necrosis factor-alpha (TNF-alpha) expression were measured in wound. Stress and control + propranolol groups presented a delay in wound contraction, re-epithelialization, F4/80-positive macrophages, neutrophils and mast cells infiltration, cellular proliferation, angiogenesis, myofibroblastic differentiation, MMP-2 and MMP-9 activation and TNF-alpha expression, whereas an increase in the nitrite levels. Stress + propranolol group presented results similar to control group. In conclusion, stress impairs cutaneous wound healing in mice through beta1- adrenoceptors and beta2-adrenoceptors activation.

Neuroprotection by radical avoidance: search for suitable agents

Neurodegeneration is frequently associated with damage by free radicals. However, increases in reactive oxygen and nitrogen species, which may ultimately lead to neuronal cell death, do not necessarily reflect its primary cause, but can be a consequence of otherwise induced cellular dysfunction. Detrimental processes which promote free radical formation are initiated, e.g., by disturbances in calcium homeostasis, mitochondrial malfunction, and an age-related decline in the circadian oscillator system. Free radicals generated at high rates under pathophysiological conditions are insufficiently detoxified by scavengers. Interventions at the primary causes of dysfunction, which avoid secondary rises in radical formation, may be more efficient. The aim of such approaches should be to prevent calcium overload, to reduce mitochondrial electron dissipation, to support electron transport capacity, and to avoid circadian perturbations. L-theanine and several amphiphilic nitrones are capable of counteracting excitotoxicity and/or mitochondrial radical formation. Resveratrol seems to promote mitochondrial biogenesis. Mitochondrial effects of leptin include attenuation of electron leakage. Melatonin combines all the requirements mentioned, additionally regulates anti- and pro-oxidant enzymes and is, with few exceptions, very well tolerated. In this review, the perspectives, problems and limits of drugs are compared which may be suitable for reducing the formation of free radicals.