Subcutaneous Adipose Tissue Layers Research Articles

Specific Features of Stromal Cells Isolated from the Two Layers of Subcutaneous Adipose Tissue: Roles of Their Secretion on Angiogenesis and Neurogenesis.

Human-adipose-tissue-derived mesenchymal stromal cells (AD-MSCs) are currently being tested as autologous-cell-based therapies for use in tissue healing and regeneration. Recent studies have also demonstrated that AD-MSC-derived exosomes contribute to tissue repair and peripheral nerve regeneration. Subcutaneous abdominal adipose tissue (AAT) is divided into two layers: the superficial layer (sAAT) and the deep layer (dAAT). However, it is unclear whether there are particular characteristics of each layer in terms of AD-MSC regenerative potential. Using AD-MSCs purified and characterized from three abdominoplasties, we compared their secretomes and exosome functions to identify which layer may be most suitable as a source for cell therapy. Phenotypical analysis of the AD-MSCs containing stromal vascular fraction did not reveal any difference between the two layers. The AD-MSC secretomes showed a very similar pattern of cytokine content and both layers were able to release exosomes with identical characteristics. However, compared to the secretome, the released exosomes showed better biological properties. Interestingly, dAAT exosomes appeared to be more effective on neuromodulation, whereas neither sAAT nor dAAT-derived exosomes had significant effects on endothelial function. It thus appears that AD-MSC-derived exosomes from the two abdominal adipose tissue layers possess different features for cell therapy.

Evaluating the Performance of Algorithms in Axillary Microwave Imaging towards Improved Breast Cancer Staging.

Breast cancer is the most common and the fifth deadliest cancer worldwide. In more advanced stages of cancer, cancer cells metastasize through lymphatic and blood vessels. Currently there is no satisfactory neoadjuvant (i.e., preoperative) diagnosis to assess whether cancer has spread to neighboring Axillary Lymph Nodes (ALN). This paper addresses the use of radar Microwave Imaging (MWI) to detect and determine whether ALNs have been metastasized, presenting an analysis of the performance of different artifact removal and beamformer algorithms in distinct anatomical scenarios. We assess distinct axillary region models and the effect of varying the shape of the skin, muscle and subcutaneous adipose tissue layers on single ALN detection. We also study multiple ALN detection and contrast between healthy and metastasized ALNs. We propose a new beamformer algorithm denominated Channel-Ranked Delay-Multiply-And-Sum (CR-DMAS), which allows the successful detection of ALNs in order to achieve better Signal-to-Clutter Ratio, e.g., with the muscle layer up to 3.07 dB, a Signal-to-Mean Ratio of up to 20.78 dB and a Location Error of 1.58 mm. In multiple target detection, CR-DMAS outperformed other well established beamformers used in the context of breast MWI. Overall, this work provides new insights into the performance of algorithms in axillary MWI.

Optical Spectral Approach to Breast Tissue Oxygen Saturation Analysis for Mastectomy Perioperative Control

The purpose of our research is to study the ability of the developed method of hemoglobin detection, based on the fiber-optic spectral analysis in visible region, to determine the level of blood supply to breast tissues before surgical treatment, intraoperatively and during observation of the patient in the postoperative period, when breast tissue is healing. The significant effect of subcutaneous adipose tissue on the shape of diffuse reflectance spectra due to scattering leads to a decrease in the accuracy of determining hemoglobin oxygen saturation and hemoglobin concentration from them. The variability of the subcutaneous adipose tissue layer is quite high, which also leads to a high variability of the spectra within a class of tissues that are in the same physiological state, which implies that the intraclass variability due to this factor should be assessed for a specific problem, not considering it random. For this purpose, in our work, we constructed optical phantoms simulating various thicknesses of the subcutaneous adipose tissue in order to determine the effect of its light scattering on the diffuse reflectance spectrum and to select the optimal configuration of optical fibers.

Phenotypical Conversions of Dermal Adipocytes as Pathophysiological Steps in Inflammatory Cutaneous Disorders.

Adipocytes from the superficial layer of subcutaneous adipose tissue undergo cyclic de- and re-differentiation, which can significantly influence the development of skin inflammation under different cutaneous conditions. This inflammation can be connected with local loading of the reticular dermis with lipids released due to de-differentiation of adipocytes during the catagen phase of the hair follicle cycle. Alternatively, the inflammation parallels a widespread release of cathelicidin, which typically takes place in the anagen phase (especially in the presence of pathogens). Additionally, trans-differentiation of dermal adipocytes into myofibroblasts, which can occur under some pathological conditions, can be responsible for the development of collateral scarring in acne. Here, we provide an overview of such cellular conversions in the skin and discuss their possible involvement in the pathophysiology of inflammatory skin conditions, such as acne and psoriasis.

Ultrasound Imaging of Abdominal Wall Endometriosis: A Pictorial Review.

Endometriosis is a debilitating disease characterized by endometrial glands and stroma outside the endometrial cavity. Abdominal wall endometriosis (AWE) indicates the presence of ectopic endometrium between the peritoneum and the skin, including subcutaneous adipose tissue and muscle layers, often following obstetric and gynecological surgical procedures. AWE is a not infrequent gynecological surgical complication, due to the increasing number of cesarean sections worldwide. In this pictorial review, we discuss the importance of medical history and physical examination, including the main ultrasound features in the diagnosis of AWE.

Using Portable Ultrasound to Monitor the Neuromuscular Reactivity to Low-Frequency Electrical Stimulation.

Neuromuscular electrical stimulation (NMES) is useful for muscle strengthening and for motor restoration of stroke patients. Using a portable ultrasound instrument, we developed an M-mode imaging protocol to visualize contractions elicited by NMES in the quadriceps muscle group. To quantify muscle activation, we performed digital image processing based on the Teager–Kaiser energy operator. The proposed method was applied for 35 voluntary patients (18 women and 17 men), of 63.8 ± 14.1 years and body mass index (BMI) 30.2 ± 6.70 kg/m2 (mean ± standard deviation). Biphasic, rectangular electric pulses of 350 µs duration were applied at two frequencies (60 Hz and 120 Hz), and ultrasound was used to assess the sensory threshold (ST) and motor threshold (MT) amplitude of the NMES signal. The MT was 23.4 ± 4.94 mA, whereas the MT to ST ratio was 2.69 ± 0.57. Linear regression analysis revealed that MT correlates poorly with body mass index (R2 = 0.004) or with the thickness of the subcutaneous adipose tissue layer that covers the treated muscle (R2 = 0.013). Our work suggests that ultrasound is suitable to visualize neuromuscular reactivity during electrotherapy. The proposed method can be used in the clinic, enabling the physiotherapist to establish personalized treatment parameters.

Anthropometrische Messungen in der NAKO Gesundheitsstudie \u2013 mehr als nur Gr\xf6\xdfe und Gewicht

ZusammenfassungÜbergewicht und Adipositas sind bedeutende Risikofaktoren für verschiedene Erkrankungen. Als Maß zu ihrer Bestimmung wurde in früheren Studien meist nur der Body-Mass-Index (BMI) verwendet. Der BMI ist allerdings ein Marker, der den Einfluss auf das Krankheitsrisiko nur unzureichend erfasst. In groß angelegten, bevölkerungsbasierten Studien besteht daher ein vordringlicher Bedarf, verbesserte Messmethoden der Körperzusammensetzung und -fettverteilung einzusetzen.Der vorliegende Beitrag stellt die in der NAKO (Nationale Kohorte) Gesundheitsstudie eingesetzten Messverfahren zur Beschreibung von Körperzusammensetzung und -fettverteilung und die ersten deskriptiven Ergebnisse vor. Diese beziehen sich auf die Daten zur Halbzeit der Basiserhebung, welche 101.817 Teilnehmende einschließt, die in 18 Studienzentren in Deutschland zwischen März 2014 und März 2017 untersucht worden sind. Die anthropometrischen Messungen umfassten Körpergewicht, Körpergröße und -umfänge, bioelektrische Impedanzanalyse (BIA), Sonographie des Abdominalfettes, 3‑D-Bodyscanner und Magnetresonanztomographie.Die Analyse des BMI zeigte, dass 46,2 % der Männer sowie 29,7 % der Frauen übergewichtig und 23,5 % der Männer und 21,2 % der Frauen adipös waren. Frauen wiesen im Mittel in fast allen Altersgruppen eine höhere Schichtdicke an subkutanem Fettgewebe auf als Männer. Die mittlere Schichtdicke des viszeralen Fettgewebes lag hingegen bei den Männern in allen Altersgruppen über den Werten der Frauen und stieg bei beiden Geschlechtern über die Altersgruppen kontinuierlich an.Die umfassenden Daten über die Körperfettverteilung und -zusammensetzung ermöglichen es zukünftig, den Einfluss von Übergewicht und Adipositas auf die Entstehung von chronischen Erkrankungen im Detail zu analysieren.

Skin Aging & Modern Edge Anti-Aging Strategies

Skin Aging & Modern Edge Anti-Aging Strategies

Skin Aging & Modern Age Anti-aging Strategies

As the most voluminous organ of the body that is exposed to the outer environment, the skin suffers from both intrinsic and extrinsic aging factors. Skin aging is characterized by features such as wrinkling, loss of elasticity, laxity, and rough-textured appearance. This aging process is accompanied with phenotypic changes in cutaneous cells as well as structural and functional changes in extracellular matrix components such as collagens and elastin. With intrinsic aging, structural changes occur in the skin as a natural consequence of the biological changes over time and produce a certain number of histological, physiological, and biochemical modifications. Intrinsic aging is determined genetically (influence of gender and ethnic group), variable in function of skin site, and also influenced by hormonal changes. Visually it is characterized by fine wrinkles. By comparison, “photoaging” is the term used to describe the changes occurring in the skin, resulting from repetitive exposure to sunlight. The histological, physiological, and biochemical changes in the different layers of the skin are much more drastic. From a mechanical point of view, human skin appears as a layered composite containing the stiff thin cover layer presented by the stratum corneum, below which are the more compliant layers of viable epidermis and dermis and further below the much more compliant adjacent layer of subcutaneous white adipose tissue.

Sex and body mass index implications on gluteofemoral subcutaneous tissue morphology visualized by ultrasonography - preliminary study.

IntroductionSince the protective value of gluteofemoral subcutaneous adipose tissue against cardiovascular risk factors has already been described in scientific reports, it is important to pay more attention to its evaluation.Aim of the studyThe purpose of this study was to evaluate sex and body mass index implications on gluteofemoral subcutaneous tissue morphology visualized by ultrasonography.Material and methodA population of 40 participants between 20–50 years of age was examined. All individuals underwent the ultrasound examination of subcutaneous adipose tissue in three locations: anterior, posterior and lateral side of a thigh in the 1/3 distal part. All examinations were collected, and the following parameters were evaluated: thickness of subcutaneous adipose tissue in general, thickness of superficial and deep subcutaneous adipose tissue.ResultsThe study revealed significant differences in the architecture of subcutaneous adipose tissue between male and female subgroups. In the group of males, a significantly thinner layer of not only subcutaneous adipose tissue in general (0.65 vs. 1.67 cm, p <0.0001), but also in its main compartments was observed. Moreover, we observed strong positive correlation between body mass index and all subcutaneous adipose tissue layers in the female subgroup. Interestingly, there was no relation between the thickness of the subcutaneous adipose tissue layers between subgroups with a decreased and normal body mass index and an increased body mass index.ConclusionsThe presented data indicates that sex is an important factor in the determination of subcutaneous adipose tissue architecture of a thigh. The ultrasound examination of this structure can be a useful prognostic tool in the assessment of cardiovascular risk.

Measurement of mean subcutaneous fat thickness: eight standardised ultrasound sites compared to 216 randomly selected sites

Ultrasound (US) provides the most accurate technique for thickness measurements of subcutaneous adipose tissue (SAT) layers. This US method was recently standardised using eight sites to capture SAT patterning and allows distinguishing between fat and embedded fibrous structures. These eight sites chosen for fat patterning studies do not represent the mean SAT thickness measured all over the body that is necessary for determining subcutaneous fat mass. This was obtained by SAT measurements at 216 sites distributed randomly all over the body. Ten participants with BMI below 28.5kgm−2 and SAT means (from eight sites) ranging from 3 mm to 10 mm were selected. The means from eight sites overestimated the means obtained from 216 sites (i.e. 2160 US measurements in the ten participants); the calibration factor of 0.65 corrects this; standard deviation (SD) was 0.05, i.e. 8%. The SD of the calibration factor transforms linearly when estimating the error range of the whole body’s SAT volume (body surface area times the calibrated mean SAT thickness). The SAT masses ranged from 3.2 to 12.4 kg in this group. The standard deviations resulting from solely the calibration factor uncertainty were ±0.3 and ±1.0 kg, respectively. For these examples, the SAT percentages were 4.9(±0.4)% and 13.3(±1.0)%.

40. Elastography: A novel evaluation of abdominal subcutaneous fat in pregnancy

Introduction Chronic inflammation leads to adipose tissue (AT) fibrosis through excessive accumulation of extracellular matrix proteins. An increasing degree of fibrosis in AT is associated with increasing body mass index (BMI) and insulin resistance. Anecdotally AT has been observed to vary with ease of ultrasound penetration on medical examinations. Ultrasound strain elastography (SE) is a useful tool in assessing fibrosis in liver disease but has not previously been used to assess AT fibrosis. This study assesses the variance in density of the two anatomical layers of subcutaneous AT, superficial subcutaneous adipose tissue (SSAT) and deep subcutaneous adipose tissue (DSAT) in pregnancy using SE. Method Women (n = 210) recruited in early pregnancy. Density of SSAT and DSAT were assessed using SE at five-time points throughout pregnancy and post-partum. Semi-quantitative density measures were achieved using two methods, strain values (SV) of the two layers calculated by the ultrasound machine and ImageJ software to calculate the percentage colour pixels in the elastography image these were correlated with the SSAT/DSAT thickness and BMI. Results Adipose tissue demonstrated a difference in density with the SSAT layer being denser than DSAT. Correlation of tissue density measures with BMI was poor. There was slight change of AT density during pregnancy with a tendency towards harder SSAT and softer DSAT in the third trimester. Post-partum SSAT became softer associated with an increase in SSAT thickness. Conclusion Elastography demonstrated density differences in adipose tissue. SE is a new method of assessing the AT demonstrating density differences in adipose tissue. Information on AT density in future work may determine AT fibrosis and be valuable for metabolic disease risk.

A novel evaluation of density differences in subcutaneous abdominal adipose tissue layers in pregnancy using elastography.

Chronic inflammation leads to adipose tissue (AT) fibrosis through excessive accumulation of extracellular matrix proteins. An increasing degree of fibrosis in AT is associated with increasing body mass index (BMI) and insulin resistance. Anecdotally AT has been observed to vary with ease of ultrasound penetration on medical examinations. Ultrasound strain elastography (SE) is a useful tool in assessing fibrosis in liver disease but has not previously been used to assess AT fibrosis. This study assesses the variance in density of the two anatomical layers of subcutaneous AT, superficial subcutaneous adipose tissue (SSAT) and deep subcutaneous adipose tissue (DSAT) in pregnancy using SE. Women (n = 210) recruited in early pregnancy. Density of SSAT and DSAT were assessed using SE at five-time points throughout pregnancy and post-partum. Semi-quantitative density measures were achieved using two methods, strain values (SV) of the two layers and ImageJ software to calculate the percentage colour pixels in the elastography image and correlated with the SSAT/DSAT thickness and BMI. Adipose tissue demonstrated a difference in density with the SSAT layer being denser than DSAT. Correlation of tissue density measures with BMI was poor. There was slight change of AT density during pregnancy with a tendency towards harder SSAT and softer DSAT in the third trimester. Post-partum SSAT became softer associated with an increase in SSAT thickness. Elastography demonstrated density differences in adipose tissue. SE is a new method of assessing the AT demonstrating density differences in adipose tissue. Information on AT density may determine AT fibrosis and be valuable for metabolic disease risk.

Skin aging as a mechanical phenomenon: The main weak links.

From a mechanical point of view, human skin appears as a layered composite containing the stiff thin cover layer presented by the stratum corneum, below which are the more compliant layers of viable epidermis and dermis and further below the much more compliant adjacent layer of subcutaneous white adipose tissue (sWAT). Upon exposure to a strain, such a multi-layer system demonstrates structural instabilities in its stiffer layers, which in its simplest form is the wrinkling. These instabilities appear hierarchically when the mechanical strain in the skin exceeds some critical values. Their appearance is mainly dependent on the mismatch in mechanical properties between adjacent skin layers or between the skin and sWAT, on the adhesive strength and thickness ratios between the layers, on their bending and tensile stiffness as well as on the value of the stress existing in single layers. Gradual reduction of elastic fibers in aging significantly reduces the skin’s ability to bend, prompting an up to 4-fold reduction of its stability against wrinkling, thereby explaining the role of these fibers in skin aging. While chronological and extrinsic aging differently modify these parameters, they lead to the same end result, reducing the critical strain required for the onset of instabilities. Comparing of mechanical properties of the skin presented as a bi-, tri- or tetra-layer structure demonstrates the particular importance of the papillary dermis in skin aging and provides the arguments to consider the undulations on the dermal-epidermal and dermal-sWAT interfaces as the result of mechanical bifurcation, leading to structural instabilities inside of the skin. According to this model, anti-aging strategies should focus not as much on the reinforcement of the dermis, but rather aim to treat the elastic mismatch between different adjacent layers in the skin and sWAT as well as the adhesion between these layers.

The origin and purpose of layers of subcutaneous adipose tissue in pigs and man.

Adipose tissue exists in many locations or depots that differ from one another based on numerous and various characteristics. The unique "layered" anatomical feature of subcutaneous adipose tissue (SAT) in man and the pig is reviewed and discussed. The origin of fetal pig adipose tissue subcutaneous layers is reviewed before the onset of adipogenesis and after the overt adipogenesis. Furthermore, the distinguishing characteristics of developing outer SAT layer (OSQ) and middle SAT layer (MSQ) in pigs are reviewed. These characteristics include adipocyte hypertrophy, metabolism and genetic regulation. The MSQ layer is the major layer in the pig and expands to the greatest degree in obesity and growth. Abdominal SAT in man is composed of deep SAT (dSAT) and superficial SAT (sSAT) layers. Clearly, dSAT expands disproportionally more than sSAT with increasing obesity in Caucasian males which precipitates a number of human pathologies associated with increased adiposity. We reviewed the considerable evidence that demonstrates the distinction between sSAT and dSAT which includes higher levels of saturated fatty acids (FAs) and greater levels of lipolysis in dSAT. Furthermore, dSAT expresses more metabolic and inflammatory genes. Studies comparing visceral adipose tissue (VAT) and dSAT indicate that both depots are implicated in insulin resistance (IR) and other human pathologies. Epigenetic studies of MSQ and dSAT have begun to indicate a role for DNA methylation in gene regulation of these depots. Further studies of dSAT and MSQ are warranted as they are clearly a major manifestation of obesity.

Measuring the Dielectric Properties of Human Skin in Order to Understand How Tumor Treating Fields Distribute Within the Body

Tumor Treating Fields (TTFields) are low intensity alternating electric fields in the 100-500 KHz frequency range that are known to have an anti-mitotic effect on cancerous cells, and are for the treatment of Glioblastoma Multiforme (GBM). Clinical trials testing the feasibility, safety and/or efficacy of TTFields therapy for various thoracic and abdominal tumors are currently underway. TTFields therapy is delivered to the patient through two pairs of transducer arrays placed on the patient's skin. The transducer arrays are made of ceramic disks with a high dielectric constant, which adhere to the body through a thin conductive medical gel. Computational studies performed by our group have shown that field intensity within the body is highly dependent on the conductivity values assigned to skin and sub-cutaneous adipose tissue (SAT). This leads to the conclusion that an accurate understanding about how TTFields distribute within the body, requires determining the dielectric properties of the skin and SAT with a high degree of accuracy. To accurately determine the properties of the skin and SAT, we measured impedance of skin folds around the waists of human volunteers in the frequency range of 100 kHz -1 MHz. The impedance measurements were performed using electrodes made of the same ceramic disks and medical gels present in the transducer arrays used to deliver TTFields to the patients. The measurements were performed by placing the electrodes on both sides of a skin fold, at 5-6 different locations around the waist of each volunteer. The thickness of the fold at each location was measured, and the impedance was plotted against the thickness of the folds. Analysis of these plots showed that in the 0.1-1 MHz frequency range, the dielectric properties of the skin can be described using a three-layer model that includes epidermis, dermis and a layer of SAT. The epidermis is modelled as a thin dielectric layer, that acts as a capacitor, which is attached in series to the dermis and SAT layers which act as resistors in series. Our analysis showed that the relative permittivity of the epidermis was 448-1190 (851 @200KHz) and the conductivities at 200 kHz of the dermis and SAT were 0.19-0.24 S/m and 0.34-0.37 S/m respectively. When assigning these conductivity values to the skin and SAT of realistic computational phantoms, and simulating application of TTFields to the torso, the total resistance measured in the model was about 30 Ohm, which is in good agreement with the total resistance measured in pancreatic cancer patients treated with TTFields. The results of this study provide new information on the dielectric properties of skin and SAT in the frequency range relevant to TTFields simulations. These measurements will lead to a better understanding of how TTFields interact with the human body.

Adolescent Obesity and Insulin Resistance: Roles of Ectopic Fat Accumulation and Adipose Inflammation

As a consequence of the global rise in the prevalence of adolescent obesity, an unprecedented phenomenon of type 2 diabetes has emerged in pediatrics. At the heart of the development of type 2 diabetes lies a key metabolic derangement: insulin resistance (IR). Despite the widespread occurrence of IR affecting an unmeasurable number of youths worldwide, its pathogenesis remains elusive. IR in obese youth is a complex phenomenon that defies explanation by a single pathway. In this review we first describe recent data on the prevalence, severity, and racial/ethnic differences in pediatric obesity. We follow by elucidating the initiating events associated with the onset of IR, and describe a distinct "endophenotype" in obese adolescents characterized by a thin superficial layer of abdominal subcutaneous adipose tissue, increased visceral adipose tissue, marked IR, dyslipidemia, and fatty liver. Further, we provide evidence for the cellular and molecular mechanisms associated with this peculiar endophenotype and its relations to IR in the obese adolescent.

The Effect of VASER Abdominal Liposuction on Metabolic Profile in Overweight Males

The aim of the current study was to examine the liposuction-induced metabolic changes with regard to release of major adipokines and insulin sensitivity in overweight male patients. Seventeen overweight male patients aged 37.15 ± 9.60 years (6 with diabetes type 2, 11 without comorbidities) and 10 age-matched healthy lean controls were enrolled in the study. Using Vibration Amplification of Sound Energy at Resonance System, ultrasound assisted liposuction was applied onto the deep layers of abdominal subcutaneous adipose tissue. The mean volume supranatant fat was 2208 ± 562 ml. To eliminate the confounding effects of postsurgical inflammation and to evaluate delayed metabolic effects, fasting blood was collected on the day of liposuction, within 1 to 2 months and more than 6 months after surgery. Serum leptin, soluble receptor for leptin, adiponectin, insulin, and glucose concentrations were tested and insulin sensitivity was calculated using updated model Homeostasis Model Assessment 2. Both treatment groups (diabetic and nondiabetic patients) experienced similar postsurgical weight reduction with concomitant lowering of body mass index value at 1 to 2 months follow-up, which was sustained after 6 months from surgery. Improvement in insulin sensitivity at 1 to 2 months follow-up was observed (p = .017 and p = .002, for diabetics and nondiabetics, respectively) and this change persisted over the next 4 months. At the same time, no significant changes in adipokines and soluble leptin receptor were found. These data demonstrate that in terms of metabolic consequences, Vibration Amplification of Sound Energy at Resonance abdominal liposuction might have beneficial effects in overweight diabetic and nondiabetic males by improving their insulin sensitivity.

Adaptation of liver stiffness measurement depth in bariatric surgery candidates with suspected nonalcoholic fatty liver disease.

A thick layer of subcutaneous adipose tissue may lead to an overestimation of liver stiffness by transient elastography. The aim of this study was to assess whether liver stiffness measurement (LSM) was overestimated using an XL probe in patients with severe obesity and, if so, to reprocess the data to the adapted depth to obtain the appropriate LSM (LSMa). A total of 152 obese patients prospectively underwent bariatric surgery and needle liver biopsy. Liver stiffness was measured by transient elastography 15 days before. To determine whether the LSM was overestimated, an expert operator retrospectively determined whether the skin-to-capsula distance was greater than 35 mm by analyzing the hyperechogenicity of ultrasound signals and the measured slope between 35 and 75 mm. In the case of an overestimation, a deeper measurement depth was selected to calculate the LSMa. There was an overestimation of the LSM obtained between 35 and 75 mm in 76 patients (50%). Among these patients, the LSMa was obtained between 40 and 75 mm in 49 patients and between 45 and 80 mm in 27 patients. Only the percentage of steatosis was independently and positively correlated with LSM overestimation. The areas under receiver operating characteristic of LSMa was 0.82±0.04 for predicting fibrosis stage F3. The Obuchowski measure was 0.85±0.02. The LSM was overestimated in severely obese patients obtained between 35 and 75 mm using an XL probe in 76 patients (50%), but LSM can be performed correctly in these patients after adapting the measurement depth to deeper beneath the patients' skin.

Macrophage Migration Inhibitory Factor in Acute Adipose Tissue Inflammation.

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine and has been implicated in inflammatory diseases. However, little is known about the regulation of MIF in adipose tissue and its impact on wound healing. The aim of this study was to investigate MIF expression in inflamed adipose and determine its role in inflammatory cell recruitment and wound healing. Adipose tissue was harvested from subcutaneous adipose tissue layers of 24 healthy subjects and from adipose tissue adjacent to acutely inflamed wounds of 21 patients undergoing wound debridement. MIF protein and mRNA expression were measured by ELISA and RT-PCR. Cell-specific MIF expression was visualized by immunohistochemistry. The functional role of MIF in cell recruitment was investigated by a chemotaxis assay and by flow cytometry of labeled macrophages that were injected into Mif –/–and wildtype mice. Wound healing was evaluated by an in vitro scratch assay on human fibroblast monolayers. MIF protein levels of native adipose tissue and supernatants from acutely inflamed wounds were significantly elevated when compared to healthy controls. MIF mRNA expression was increased in acutely inflamed adipose tissue indicating the activation of MIF gene transcription in response to adipose tissue inflammation. MIF is expressed in mature adipocytes and in infiltrated macrophages. Peripheral blood mononuclear cell migration was significantly increased towards supernatants derived from inflamed adipose tissue. This effect was partially abrogated by MIF-neutralizing antibodies. Moreover, when compared to wildtype mice, Mif –/–mice showed reduced infiltration of labeled macrophages into LPS-stimulated epididymal fat pads in vivo. Finally, MIF antibodies partially neutralized the detrimental effect of MIF on fibroblast wound healing. Our results indicate that increased MIF expression and rapid activation of the MIF gene in fat tissue adjacent to acute wound healing disorders may play a role in cell recruitment to the site of inflammation and wound healing.