Regulation of Lymphatic Function in Obesity

Yeast hydrolysate and exercise ameliorate high-fat diet-induced obesity in C57BL/6 mice

BACKGROUND

Yeast hydrolysate (YH) has been shown to be effective in inhibiting fat accumulation. This study aimed to investigate the effects of YH and exercise on high-fat diet-induced obesity and their underlying mechanisms in C57BL/6J mice.

METHODS

In this study, 6-week-old C57BL/6 mice were divided into 7 groups; a normal group fed a normal chow diet, an HFD group (CON) fed ad libitum, an exercise group (15m/min, 30min), an HFD supplemented with low dose of YH (100 mg/kg, YHL), an HFD supplemented with high dose of YH (200 mg/kg, YHH), and a combination of exercise and YHH group. After 12 weeks of HFD and YH administration, white adipocytes and liver tissue were analyzed.

RESULTS

Both YH and exercise significantly reduced the weight of the body and adipose tissues; however, the greatest effect was observed when YH and exercise were combined. Similarly, most reduction in adipocyte size and fat formation in the liver was notable following the combination of YH and exercise. Furthermore, both YH and exercise effectively downregulated lipid synthesis genes, namely fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), and HMG-CoA reductase (HMGCR), and SREBP1 and SREBP2 proteins. YH and/or exercise also significantly increased the mRNA levels of hormone sensitive lipase (HSL) and carnitine palmitoyltransferase 1 (CPT1), both of which are related to fatty acid oxidation. In addition, pAMPKα and PPARα levels were significantly increased by YH and exercise, with the greatest increase noted following the combination of YH and exercise. Additionally, YH and exercise combined caused the most significant increase in the antioxidant response, as evidenced by nuclear factor erythroid 2-related factor 2 (Nrf2) and superoxide dismutase 1 (SOD1) upregulation at protein and mRNA levels. Their combination also exhibited strongest suppression of inflammatory responses via the downregulation of NF-κB, TNF-α, and IL-1β at protein and mRNA levels. Collectively, YH and exercise combination showed an inhibitory effect on obesity, leading to decreased lipogenesis and increased lipolysis, with favorable regulation of antioxidant and inflammatory responses.

CONCLUSION

This study suggests the potential use of a combination of physical activity and YH supplementation to control obesity and related metabolic diseases.

Insulin regulates lymphatic endothelial integrity via palmitoylation

Lipid metabolism plays a critical role in lymphatic endothelial cell (LEC) development and vessel maintenance. Altered lipid metabolism is associated with loss of lymphatic vessel integrity, which compromises organ function, protective immunity, and metabolic health. Thus, understanding how lipid metabolism affects LECs is critical for uncovering the mechanisms underlying lymphatic dysfunction. Protein palmitoylation, a lipid-based post-translational modification, has emerged as a critical regulator of protein function, stability, and interaction networks. Insulin, a master regulator of systemic lipid metabolism, also regulates protein palmitoylation. However, the role of insulin-driven palmitoylation in LEC biology remains unexplored. To examine the role of palmitoylation in LEC function, we generated the first palmitoylation proteomics profile in human LECs, validated insulin-regulated targets, and determined the role of palmitoylation in LEC barrier function. In unstimulated conditions, palmitoylation occurred primarily on proteins involved in vesicular and membrane trafficking, and in translation initiation. Insulin treatment, instead, enriched palmitoylation of proteins involved in LEC integrity, namely junctional proteins such as claudin 5, along with small GTPases and ubiquitination enzymes. We also investigated the role of the long-chain fatty acid transporter CD36, a major mediator of palmitate uptake into cells, in regulating optimal lymphatic protein palmitoylation. CD36 silencing in LECs increased by 2-fold palmitoylation of proteins involved in inflammation and immune cell activation. Overall, our findings provide novel insights into the intricate relationship between lipid modification and LEC function, suggesting that insulin and palmitoylation play a critical role in lymphatic endothelial function.

Obesity-Associated Conditions Hinder Solute Drainage Function of Engineered Human Lymphatic Vessels

Purpose

Obesity is associated with poor lymphatic solute drainage. It is unclear whether the chronic inflammation, hypoxia, and hyperlipidemia that are together associated with obesity cause impaired drainage function, and if so, whether these conditions act directly on lymphatic endothelial cells (LECs) or are indirectly mediated by the mechanical properties or cellular composition of the surrounding tissue.

Methods

We engineered blind-ended lymphatic vessels in type I collagen gels and simulated the obese microenvironment with a cocktail of tumor necrosis factor (TNF)-α, cobalt chloride (CoCl2), and oleate, which model inflammation, hypoxia, and hyperlipidemia, respectively. We compared the solute drainage rate and leakage of lymphatics that were exposed to simulated obesity or not. We performed similar assays with lymphatics in stiffened gels, in adipocyte-laden gels, or in the presence of conditioned medium (CM) from adipose cells treated with the same cocktail.

Results

Lymphatics that were exposed to simulated obesity exhibited more gaps in endothelial junctions, leaked more solute, and drained solute less quickly than control lymphatics did, regardless of matrix stiffness. CM from adipose cells that were exposed to simulated obesity did not affect lymphatics. Lymphatics in adipocyte-laden gels did not exhibit worse drainage function when exposed to simulated obesity.

Conclusions

The combination of obesity-associated inflammation, hypoxia, and hyperlipidemia impairs lymphatic solute drainage and does so by acting directly on LECs. Surprisingly, adipocytes may play a protective role in preventing obesity-associated conditions from impairing lymphatic solute drainage.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-024-00840-z.

The Effect of Autologous Dendritic Cell Immunotherapy on Kidney Function and Endothelial Dysfunction of Patients with Diabetic Kidney Disease (DKD): An Open Label Clinical Trial

This study aimed to evaluate the effects of autologous dendritic cell (DC) immunotherapy on clinical outcomes (glomerular filtration rate/GFR and urine creatinine albumin ratio/UACR) and endothelial dysfunction (ICAM, VCAM, VEGF) in patients with diabetic kidney disease (DKD). Endothelial dysfunction induced by inflammation is one of the key factors in the pathogenesis of DKD. In this one-group pretest-posttest quasi-experimental study, 69 subjects with DKD were administered a single dose of autologous DC immunotherapy ex vivo. UACR was measured at baseline and at weeks 1, 2, 3, and 4, while ICAM, VCAM, VEGF, and GFR were measured at baseline and at week 4 post-immunotherapy. The results showed a significant reduction in median UACR from 250 (IQR 71-668) mg/g at baseline to 164 (IQR 49-576) mg/g at week 4 (p < 0.05). GFR did not show any significant changes after immunotherapy. HbA1c (B = -33.270, p = 0.021) and baseline UACR (B = -0.185, p < 0.001) were identified as significant predictors of UACR change. Although there were no significant changes in ICAM, VCAM, and VEGF, subgroup analysis revealed a decrease in VCAM in macroalbuminuria patients and an increase in those with good glycemic control, suggesting differing endothelial responses. In conclusion, autologous DC immunotherapy effectively reduced UACR in DKD patients, and significant VCAM changes were found in macroalbuminuria and good glycemic control subjects. Further research is needed to understand the mechanisms behind UACR reduction and the long-term impact of this therapy.

Postoperative Morbidity and Factors Predicting the Development of Lymphoceles Following Lateral Pelvic Node Dissection for Rectal Cancer: A Cohort Study

PURPOSE

Lateral pelvic node dissection (LPLND) is indicated in the surgical management of clinically significant pelvic lymphadenopathy associated with rectal malignancies. However, procedure-related morbidity, including the incidence and predisposing factors for lymphoceles arising in this setting have not been adequately evaluated.

METHODS

This retrospective single-institution study included 183 patients with nonmetastatic, lateral node-positive rectal cancer undergoing total mesorectal excision with LPLND between June 2014 and May 2023 to determine the incidence and severity of postoperative complications using the Clavien-Dindo system, with logistic regression performed to model a relationship between lymphocele-development and potentially-predictive variables.

RESULTS

In this cohort, mean age was 45.3 ± 12.81 years, 62.8% were male, and 27.9% had body mass index ≥ 25 kg/m2. Median tumor-distance from the verge was 3.0 (interquartile range [IQR] 1.0-5.0) cm. Following radiotherapy in 86.9%, all patients underwent surgery: 30.1% had open resection and 26.2% had bilateral LPLND. Median nodal-yield was 6 (IQR 4-8) per side. Postoperatively, 45.3% developed complications, with 18% considered clinically significant. Lymphoceles, detected in 21.3%, comprised the single-most common sequelae following LPLND, 46.2% arising within 30 days of surgery and 33.3% requiring intervention. On multivariate analyses, obesity (hazard ratio [HR] 2.496; 95% confidence interval [CI] 1.094-5.695), receipt of preoperative radiation (HR 10.026; 95% CI 1.225-82.027), open surgical approach (HR 2.779; 95% CI 1.202-6.425), and number of harvested nodes (HR 1.105; 95% CI 1.026-1.190) were significantly associated with lymphocele-development.

CONCLUSIONS

Pelvic lymphoceles and its attendant complications represent the most commonly encountered morbidity following LPLND for rectal cancer, with obesity, neoadjuvant radiotherapy, open surgery, and higher nodal-yield predisposing to their development.

Insights into diet, psychological distress, and personality traits among patients with lower-extremity lymphedema and overweight/obesity in comparison to patients with lifestyle-induced overweight/obesity and patients with normal body weight

Obesity is a leading cause of cardiovascular diseases. There are significant and mutual associations between lymphatic dysfunction and obesity. This case-control study aimed to compare nutrient intake, depressive symptoms, and Eysenck's personality traits in patients with lower extremity lymphedema and overweight/obesity (n = 34) in comparison to patients with lifestyle-induced overweight/obesity (n = 30) and patients with normal body weight (n = 30). The study groups were evaluated using the Food Frequency Questionnaire (FFQ), Beck Depression Inventory-II, and Eysenck Personality Questionnaire-Revised (EPQ-R). Surprisingly, the study groups did not differ in any item in the FFQ, including total daily energy value and total intake of macronutrients, vitamins, or minerals. The group with lymphedema and overweight/obesity had higher scores on the depression scale, and the groups with lymphedema and overweight/obesity and lifestyle-induced overweight/obesity differed from the control group in Eysenck's psychoticism score; however, in all study groups, the scores of this trait were within the normal range. In conclusion, our study suggests that when FFQ is used, the problem of under-reporting of usual dietary intake among patients with lower extremity lymphedema and overweight/obesity, and lifestyle-induced overweight/obesity should be considered.

Sentinel Lymph Node Detection Using SPECT and Gamma Probe in Low-Risk Endometrial Cancer: Efficacy and Factors Associated With Detection Failure

INTRODUCTION

This study examined factors that affected sentinel lymph node (SLN) identification of patients with endometrial cancer having a preoperative estimation of low recurrent risk.

METHODS

This study included 97 patients with endometrial cancer who attempted to identify SLN using a uterine cervical injection of technetium-99 m phytate under laparoscopic or robotic-assisted surgery at our institute. A preoperative single photon emission computed tomography (SPECT) and intraoperative gamma probe were used to detect hot nodes. Multiple clinical factors, including age, body mass index (BMI), and so on, were investigated for their association with SLN mapping failure.

RESULTS

Among 97 cases, SPECT failed to detect SLN unilaterally in 38 cases (39%) and on both sides in 9 cases (9%). Meanwhile, the gamma probe failed to detect SLN unilaterally in 23 cases (24%) and on both sides in 3 cases (3%). While only age was significantly associated with SLN detection failure using the SPECT detection system, both age and BMI were significantly associated with SLN detection failure using the gamma probe detection system. When limiting to the preoperative SLN detection failure cohort of 47 cases, there was a strong association between intraoperative SLN detection failure and BMI, but not age.

CONCLUSION

The SLN biopsy system was effectively applied to patients with endometrial cancer who underwent minimally invasive surgery (MIS). Attempts to improve SLN identification in older patients and those with obesity are warranted to obtain maximum benefits of MIS for low- or medium-risk cases.

Size Matters: Predicting Surgical Site Infection After Whole Breast Radiotherapy in the Era of Hypofractionation

Objectives: Few studies have analyzed surgical site infections associated with hypofractionated RT. The purpose of this study was to identify risk factors for surgical site infections with a particular focus on volumetric parameters that reflect the size of the volumes treated, including tumors, surgical cavities, and breasts. Methods: A total of 145 early breast cancer patients who were surgically staged 0-II undergoing hypofractionated RT on the whole breast were retrospectively reviewed. Tumor size (cm) was measured from surgical pathology. Surgical cavity volume (cc) and breast volume (cc) were calculated by segmenting each axial slice of simulation CT. The cavity-to-breast ratio (%) was calculated as surgical cavity volume/breast volume × 100. Results: The incidence of surgical site infection was 4.8% at a median of 6.3 months after the completion of RT. In univariate analysis, tumor size (OR 2.01, p = 0.025), surgical cavity volume (OR 1.03, p = 0.013), cavity-to-breast ratio (OR 1.29, p = 0.005), and BMI (OR 1.23, p = 0.014) were significantly associated with surgical site infection. In multivariate analysis, the cavity-to-breast ratio (OR 1.24, p = 0.039) remained significantly associated with surgical site infection. Conclusions: This study highlights the importance of volumetric parameters, specifically the cavity-to-breast ratio, as significant predictors of surgical site infection in a pure cohort of early breast cancer patients undergoing breast-conserving surgery and hypofractionated RT. Tailored approaches, including the use of prophylactic antibiotics, prophylactic aspiration, and close follow-up, may reduce the morbidity associated with surgical site infection and prevent the potential compromise of tumor outcomes.

A Randomized Controlled Trial on the Efficacy of 20% Human Albumin in Reducing Pleural Effusion After Cardiopulmonary Bypass

Background/Objectives: Cardiopulmonary bypass can lead to hemodilution, causing a fluid shift to the interstitial space. Albumin helps counteract the intravascular fluid movement to the extravascular space and reduces the risk of complications associated with fluid imbalance. Our main objective was to evaluate the effectiveness of albumin addition in the cardiopulmonary bypass priming solution compared to standard priming, focusing on its role in reducing pleural effusion development. Methods: This was a single-center randomized controlled trial conducted at a tertiary care hospital specializing in cardiology and cardiac surgery. It involved 70 individuals scheduled for elective open-heart surgery. All cases were randomly assigned into two groups of 35 patients. The study group replaced 100 mL of standard CPB priming solution with 100 mL of 20% human albumin. We measured serum albumin levels before and after the surgery, 6 and 12 h after, and calculated colloid oncotic pressure. Thorax CT scans were performed on the first postoperative day to measure and calculate pleural effusion volume. Results: Albumin addition to cardiopulmonary bypass priming solution led to a significant reduction in pleural effusion development after CPB. An albumin level <35 g/L after the surgery showed a significant increase in pleural effusion development, and 100 mL of 20% albumin was sufficient to maintain serum albumin levels > 35 g/L. Conclusions: Our study suggests a link between postoperative hypoalbuminemia and the early development of pleural effusion after CPB, as well as the possible benefits of adding 100 mL of 20% albumin compared to standard crystalloid CPB priming to minimize postoperative pleural effusion development.

Development and validation of a nomogram for predicting the risk of postoperative fracture blister after pilon fracture

Background

Fracture blister (FB) is one of the most common complications in pilon fractures. This study aimed to construct and validate a nomogram for predicting postoperative FB risk in patients with pilon fractures.

Methods

We retrospectively collected information on 1,119 patients with lower extremity fractures in the 3rd Hospital of Hebei Medical University between January 2023 and January 2024. Patients with FBs were considered as the FB group and those without FB as the non-FB group. Variables with a significance level of P < 0.05 in the univariate analysis were included in the multivariate logistic regression analysis. The backward stepwise regression method was applied to identify independent risk factors associated with FB. The selected predictors were then entered into R software for further analysis and Nomogram construction.

Results

In our research, the rate of FB (119 of 1,119) was 10.63%. Several predictors of FB were found using univariate analysis, including body mass index (BMI) (p < 0.001), the presence of DVT (p < 0.001), closed fractures (p < 0.001), time from injury to admission (p < 0.001), smoking history (p < 0.01), not utilizing dehydrating agents (p < 0.010), fixation mode of fracture (p < 0.001), the mode of surgical suture (p < 0.001), postoperative infection (p < 0.001) and Elixhauser comorbidity index (ECI) (p < 0.01). In addition, FB group exhibited significantly higher levels of blood serum indicators, such as EOS (p = 0.029), HCT (p < 0.01), LYM (p = 0.01), MPV (p = 0.014), NEU (p < 0.01), CKMB (p < 0.01), PLT (p < 0.01), ALB (p < 0.01), ALP (p < 0.01), AST (p < 0.01), CK (p = 0.019), CREA(p < 0.01), DBIL (p < 0.01), GLU (p < 0.01), Na (p < 0.01), P (p < 0.01), TC (p = 0.024), ALT (p < 0.01), TCO2 (p < 0.01), TG (p < 0.01), TP (p < 0.01), UA (p = 0.018), UREA (p = 0.033) compared to the non-FB group. According to the stepwise logistic regression analysis, higher BMI (p = 0.011, OR 0.873, 95% CI 0.785-0.970), NEU (p = 0.036, OR 0.982, 95% CI 0.865-0.995) and CKMB (p < 0.014, OR 0.994, 95% CI 0.989-0.999) were associated with increased FB risk, while plate fixation (p = 0.017, OR 0.371, 95% CI 0.123-0.817), the mode of surgical suture (p < 0.01, OR 0.348, 95% CI 0.161-0.749), and postoperative infection (p = 0.020, OR 0.406, 95% CI 0.190-0.866) were also correlated with increased FB risk. The nomogram was established based on 6 predictors independently related to FB.

Conclusions

Our investigation has shown that BMI, NEU, CKMB, plate fixation, the mode of surgical suture, and postoperative infection are independent risk factors for FB in patients with pilon fractures. The predictors identified by the nomogram could potentially be used to assess the possibility of blister formation, which could be a sign of fascial compartmental pressure release.

Lymphatic Capillarization in Different Fiber Types of Rat Skeletal Muscles With Growth and Age

OBJECTIVE

To clarify the effect of growth and advancing age on lymphatic capillarization in rat skeletal muscles, we examined the histological and biochemical changes of lymphatic capillaries in different fiber types of skeletal muscles across juvenile, young, and middle-aged generations.

METHODS

We collected the tibialis anterior (TA), extensor digitorum longus (EDL), and soleus (SOL) muscles. Immunohistochemical staining using LYVE-1 and CD31 markers was used for lymphatic and blood capillaries, respectively. Real-time PCR was used to analyze mRNA expression of lymphangiogenic factors.

RESULTS

The density of LYVE-1-positive lymphatic capillaries in the muscles peaked during the juvenile period and subsequently decreased with increasing age. In contrast to blood capillaries, fast-twitch dominant muscles (i.e., TA and EDL) exhibited an age-related decrease in lymphatic capillaries. Similar to blood capillaries, lymphatic capillaries were abundant in SOL, a slow-twitch dominant muscle, which showed less susceptibility to age-related lymphatic decline. The mRNA expression of lymphangiogenic factors was significantly upregulated in SOL and decreased in all muscles of middle-aged rats.

CONCLUSIONS

The age-related decrease of lymphatic capillaries in fast-twitch muscles might be associated with age-related muscle atrophy.

Association of Cellulitis With Obesity: Systematic Review and Meta-Analysis

BACKGROUND

Cellulitis is a bacterial skin infection that tends to recur. Previous studies have identified several risk factors that may contribute to its pathogenesis. Obesity is an increasingly prevalent worldwide disease that has been associated with skin and soft tissue infections.

OBJECTIVE

The aim of our systematic review and meta-analysis was to investigate the association of cellulitis with obesity.

METHODS

The Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Web of Science databases were searched for the relevant studies from the inception of each respective database to March 13, 2021. Case-control, cross-sectional, or cohort studies that examined the odds or risk of increased BMI in patients with cellulitis were included. This study was carried out in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The Newcastle-Ottawa scale (NOS) was used to evaluate the risk of bias in included studies.

RESULTS

In total, 9 case-control studies were included in our quantitative meta-analysis with a total of 68,148 study participants. A significant association was found between cellulitis and obesity (pooled odds ratio [OR] 2.67, 95% CI 1.91-3.71). No significant association was observed between cellulitis and being overweight (pooled OR 1.69, 95% CI 0.99-2.88). Patients with cellulitis were also found to have 1.63-fold increased odds of being male (pooled OR 1.63, 95% CI 1.12-2.38).

CONCLUSIONS

Our findings suggest that cellulitis is significantly associated with obesity. Maintaining a healthy BMI may be indicated for patients presenting with cellulitis.

Loss of anoctamin 1 reveals a subtle role for BK channels in lymphatic muscle action potentials

Ca2+ signalling plays a crucial role in determining lymphatic muscle cell excitability and contractility through its interaction with the Ca2+-activated Cl- channel anoctamin 1 (ANO1). In contrast, the large-conductance (BK) Ca2+-activated K+ channel (KCa) and other KCa channels have prominent vasodilatory actions by hyperpolarizing vascular smooth muscle cells. Here, we assessed the expression and contribution of the KCa family to mouse and rat lymphatic collecting vessel contractile function. The BK channel was the only KCa channel consistently expressed in fluorescence-activated cell sorting-purified mouse lymphatic muscle cell lymphatic muscle cells. We used a pharmacological inhibitor of BK channels, iberiotoxin, and small-conductance Ca2+-activated K+ channels, apamin, to inhibit KCa channels acutely in ex vivo isobaric myography experiments and intracellular membrane potential recordings. In basal conditions, BK channel inhibition had little to no effect on either mouse inguinal-axillary lymphatic vessel (MIALV) or rat mesenteric lymphatic vessel contractions or action potentials (APs). We also tested BK channel inhibition under loss of ANO1 either by genetic ablation (Myh11CreERT2-Ano1 fl/fl, Ano1ismKO) or by pharmacological inhibition with Ani9. In both Ano1ismKO MIALVs and Ani9-pretreated MIALVs, inhibition of BK channels increased contraction amplitude, increased peak AP and broadened the peak of the AP spike. In rat mesenteric lymphatic vessels, BK channel inhibition also abolished the characteristic post-spike notch, which was exaggerated with ANO1 inhibition, and significantly increased the peak potential and broadened the AP spike. We conclude that BK channels are present and functional on mouse and rat lymphatic muscle cells but are otherwise masked by the dominance of ANO1. KEY POINTS: Mouse and rat lymphatic muscle cells express functional BK channels. BK channels make little contribution to either rat or mouse lymphatic collecting vessel contractile function in basal conditions across a physiological pressure range. ANO1 limits the peak membrane potential achieved in the action potential and sets a plateau potential limiting the voltage-dependent activation of BK. BK channels are activated when ANO1 is absent or blocked and slightly impair contractile strength by reducing the peak membrane potential achieved in the action potential spike and accelerating the post-spike repolarization.

Dysregulation of Lymphatic Endothelial VEGFR3 Signaling in Disease

Vascular endothelial growth factor (VEGF) receptor 3 (VEGFR3), a receptor tyrosine kinase encoded by the FLT4 gene, plays a significant role in the morphogenesis and maintenance of lymphatic vessels. Under both normal and pathologic conditions, VEGF-C and VEGF-D bind VEGFR3 on the surface of lymphatic endothelial cells (LECs) and induce lymphatic proliferation, migration, and survival by activating intracellular PI3K-Akt and MAPK-ERK signaling pathways. Impaired lymphatic function and VEGFR3 signaling has been linked with a myriad of commonly encountered clinical conditions. This review provides a brief overview of intracellular VEGFR3 signaling in LECs and explores examples of dysregulated VEGFR3 signaling in various disease states, including (1) lymphedema, (2) tumor growth and metastasis, (3) obesity and metabolic syndrome, (4) organ transplant rejection, and (5) autoimmune disorders. A more complete understanding of the molecular mechanisms underlying the lymphatic pathology of each disease will allow for the development of novel strategies to treat these chronic and often debilitating illnesses.

Prevalence and risk factors of lymphatic dysfunction in cirrhosis patients with refractory ascites: An often unconsidered mechanism

BACKGROUND

The lymphatic system is crucial in maintaining the body fluid homeostasis. A dysfunctional lymphatic system may contribute to the refractoriness of ascites and edema in cirrhosis patients. Therefore, assessment of lymphatic dysfunction in cirrhosis patients with refractory ascites (RA) can be crucial as it would call for using different strategies for fluid mobilization.

AIM

To assessing the magnitude, spectrum, and clinical associations of lymphatic dysfunction in liver cirrhosis patients with RA.

METHODS

This observational study included 155 consecutive cirrhosis patients with RA. The presence of clinical signs of lymphedema, such as peau d'orange appearance and positive Stemmer sign, intestinal lymphangiectasia (IL) on duodenal biopsy seen as dilated vessels in the lamina propria with strong D2-40 immunohistochemistry, and chylous ascites were used to diagnose the overt lymphatic dysfunctions.

RESULTS

A total of 69 (44.5%) patients out of 155 had evidence of lymphatic dysfunction. Peripheral lymphedema, found in 52 (33.5%) patients, was the most common manifestation, followed by IL in 42 (27.0%) patients, and chylous ascites in 2 (1.9%) patients. Compared to patients without lymphedema, those with lymphedema had higher mean age, median model for end-stage liver disease scores, mean body mass index, mean ascitic fluid triglyceride levels, and proportion of patients with hypoproteinemia (serum total protein < 5 g/dL) and lymphocytopenia (< 15% of total leukocyte count). Patients with IL also had a higher prevalence of lymphocytopenia and hypoproteinemia (28.6% vs. 9.1%, P = 0.004). Seven (13%) patients with lymphedema had lower limb cellulitis compared to none in those without it. On multivariate regression analysis, factors independently associated with lymphatic dysfunction included obesity [odds ratio (OR): 4.2, 95% confidence intervals (95%CI): 1.1-15.2, P = 0.027], lymphocytopenia [OR: 6.2, 95%CI: 2.9-13.2, P < 0.001], and hypoproteinemia [OR: 3.7, 95%CI: 1.5-8.82, P = 0.003].

CONCLUSION

Lymphatic dysfunction is common in cirrhosis patients with RA. Significant indicators of its presence include hypoproteinemia and lymphocytopenia, which are likely due to the loss of lymphatic fluid from the circulation. Future efforts to mobilize fluid in these patients should focus on methods to improve lymphatic drainage.

Novel use and utilization of robotic Hoyer-Hook system for suspension of panniculus morbidus

Panniculus morbidus is a complication of morbid obesity characterized by massive abdominal folds that hang below the beltline. Ulceration, dermatitis, and sinus tract formation of the pannus can cause significant morbidity to the patient and impair activities of daily living. If patients fail medical management, the next step is surgical excision. Challenging aspects of the procedure include adequate suspension of the pannus, cost, and prevention of intra-abdominal injuries. We present a case of a 70-year-old female with panniculus morbidus with endometrial carcinoma. We successfully performed a panniculectomy using a novel combination of towel hooks and the Hoyer lift to suspend the abdomen. In the same anesthesia event, she underwent robotic-assisted hysterectomy. No intra-operative or post-operative complications were encountered, and the patient was satisfied with her results. In this case, we demonstrated an effective and cost-efficient approach to panniculectomy in the severely obese patient.

Junctional integrity and directional mobility of lymphatic endothelial cell monolayers are disrupted by saturated fatty acids

The lymphatic circulation regulates transfer of tissue fluid and immune cells toward the venous circulation. While obesity impairs lymphatic vessel function, the contribution of lymphatic endothelial cells (LEC) to metabolic disease phenotypes is poorly understood. LEC of lymphatic microvessels are in direct contact with the interstitial fluid, whose composition changes during the development of obesity, markedly by increases in saturated fatty acids. Palmitate, the most prevalent saturated fatty acid in lymph and blood, is detrimental to metabolism and function of diverse tissues, but its impact on LEC function is relatively unknown. Here, palmitate (but not its unsaturated counterpart palmitoleate) destabilized adherens junctions in human microvascular LEC in culture, visualized as changes in VE-cadherin, α-catenin, and β-catenin localization. Detachment of these proteins from cortical actin filaments was associated with abundant actomyosin stress fibers. The effects were Rho-associated protein kinase (ROCK)- and myosin-dependent, as inhibition with Y27632 or blebbistatin, respectively, prevented stress fiber accumulation and preserved junctions. Without functional junctions, palmitate-treated LEC failed to directionally migrate to close wounds in two dimensions and failed to form endothelial tubes in three dimensions. A reorganization of the lymphatic endothelial actin cytoskeleton may contribute to lymphatic dysfunction in obesity and could be considered as a therapeutic target.

Adipose Tissue in Lymphedema: A Central Feature of Pathology and Target for Pharmacologic Therapy

Lymphedema is a chronic condition of impaired lymphatic flow that results in limb swelling and debilitation. The pathophysiology of lymphedema is characterized by lymphatic stasis that triggers inflammation, fibrosis, and adipose tissue deposition in the extremities. Most often, this condition occurs in cancer survivors in the years after treatment with combinations of surgery, radiation, or chemotherapy, with the major risk factor being lymph node dissection. Interestingly, obesity and body mass index are independent risk factors for development of lymphedema, suggesting interactions between adipose and lymphatic tissue biology. Currently, treatment of lymphedema involves palliative approaches, including compression garments and physical therapy, and surgical approaches, including liposuction, lymphovenous bypass, and vascularized lymph node transfer. Emerging lymphedema therapies that focus on weight loss or reducing inflammation have been tested in recent clinical trials, yielding mixed results with no effect on limb volumes or changes in bioimpedance measurements. These studies highlight the need for novel therapeutic strategies that target the driving forces of lymphedema. In this light, animal models of lymphedema demonstrate a role of adipose tissue in the progression of lymphedema and suggest these processes may be targeted in the treatment of lymphedema. Herein, we review both conventional and experimental therapies for lymphedema as well as the defining characteristics of its pathophysiology. We place emphasis on the aberrant fibroadipose tissue accumulation in lymphedema and propose a new approach to experimental treatment at the level of adipocyte metabolism.

Lower Limb Lipedema-Superficial Lymph Flow, Skin Water Concentration, Skin and Subcutaneous Tissue Elasticity

Background: Lipedema of lower limbs is characterized by bilateral accumulations of excess adipose tissue starting from the ankle to the hips and buttocks. The studies with lymphoscintigraphy (LSC) and magnetic resonance (MR) lymphography show altered transport index and enlarged lymphatic vessels (LVs). Our studies aimed to investigate the superficial lymph flow, water accumulation, skin and subcutaneous tissue elasticity, and the possibility of using this information to diagnose lipedema. Methods and Results: Fifty patients with lipedema and 50 control subjects (women) were included. The Indocyanine Green (ICG) lymphography, LSC, skin water measurement, skin durometry, and deep tissue tonometry were done in all participants. ICG lymphography revealed: (1) Slower lymph flow in lipedema patients; after 3 minutes of feet movement in a horizontal position, the ICG-dyed lymph reached the upper calf level in 8% of lipedema patients compared with 56% in the control group (p ˂ 0.0001). (2) More than three LVs were noticed more often in lipedema patients. (3) The higher number of abnormal LV images at all limb levels and during each observation stage with a statistically significant number of foggy and dilated. (4) Statistically significant higher fluorescent intensity in all limb levels. Skin water concentration was higher in the feet in lipedema (p = 0.000189). Conclusion: Our studies have shown the differences in superficial lymph flow and water concentration between lipedema and normal limbs. Data proove the usefulness of ICG lymphography, skin water concentration and skin and subcutaneous tissue elasticity measurements in diagnosing lipedema.

Subcutaneous Adipose Tissue Edema in Lipedema Revealed by Noninvasive 3T MR Lymphangiography

BACKGROUND

Lipedema exhibits excessive lower-extremity subcutaneous adipose tissue (SAT) deposition, which is frequently misidentified as obesity until lymphedema presents. MR lymphangiography may have relevance to distinguish lipedema from obesity or lymphedema.

HYPOTHESIS

Hyperintensity profiles on 3T MR lymphangiography can identify distinct features consistent with SAT edema in participants with lipedema.

STUDY TYPE

Prospective cross-sectional study.

SUBJECTS

Participants (48 females, matched for age [mean = 44.8 years]) with lipedema (n = 14), lipedema with lymphedema (LWL, n = 12), cancer treatment-related lymphedema (lymphedema, n = 8), and controls without these conditions (n = 14).

FIELD STRENGTH/SEQUENCE

3T MR lymphangiography (nontracer 3D turbo-spin-echo).

ASSESSMENT

Review of lymphangiograms in lower extremities by three radiologists was performed independently. Spatial patterns of hyperintense signal within the SAT were scored for extravascular (focal, diffuse, or not apparent) and vascular (linear, dilated, or not apparent) image features.

STATISTICAL TESTS

Interreader reliability was computed using Fleiss Kappa. Fisher's exact test was used to evaluate the proportion of image features between study groups. Multinomial logistic regression was used to assess the relationship between image features and study groups. The odds ratio (OR) and 95% confidence interval (CI) of SAT extravascular and vascular features was reported in groups compared to lipedema. The threshold of statistical significance was P < 0.05.

RESULTS

Reliable agreement was demonstrated between three independent, blinded reviewers (P < 0.001). The frequency of SAT hyperintensities in participants with lipedema (36% focal, 36% diffuse), LWL (42% focal, 33% diffuse), lymphedema (62% focal, 38% diffuse), and controls (43% focal, 0% diffuse) was significantly distinct. Compared with lipedema, SAT hyperintensities were less frequent in controls (focal: OR = 0.63, CI = 0.11-3.41; diffuse: OR = 0.05, CI = 0.00-1.27), similar in LWL (focal: OR = 1.29, CI = 0.19-8.89; diffuse: OR = 1.05, CI = 0.15-7.61), and more frequent in lymphedema (focal: OR = 9.00, CI = 0.30-274.12; diffuse: OR = 5.73, CI = 0.18-186.84).

DATA CONCLUSION

Noninvasive MR lymphangiography identifies distinct signal patterns indicating SAT edema and lymphatic load in participants with lipedema.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 1.

Adipose endothelial cells mastering adipose tissues metabolic fate

Dynamic communication within adipose tissue depends on highly vascularized structural characteristics to maintain systemic metabolic homoeostasis. Recently, it has been noted that adipose endothelial cells (AdECs) act as essential bridges for biological information transmission between adipose-resident cells. Hence, paracrine regulators that mediate crosstalk between AdECs and adipose stromal cells were summarized. We also highlight the importance of AdECs to maintain adipocytes metabolic homoeostasis by regulating insulin sensitivity, lipid turnover and plasticity. The differential regulation of AdECs in adipose plasticity often depends on vascular density and metabolic states. Although choosing pro-angiogenic or anti-angiogenic therapies for obesity is still a matter of debate in clinical settings, the growing numbers of drugs have been confirmed to play an anti-obesity effect by affecting vascularization. Pharmacologic angiogenesis intervention has great potential as therapeutic strategies for obesity.

The origin of lumbar subcutaneous edema: two case reports

Since magnetic resonance imaging (MRI) is widely used to evaluate complaints of low back pain, there have been many reports of lumbar subcutaneous edema (LSE). However, the mechanism underlying its development is unknown. We herein report 2 cases that showed the reduction of LSE. These cases suggest details concerning the mechanism underlying the development of LSE. The first case was an obese 70-year-old woman with a history of chronic back pain due to lumbar canal stenosis. MRI revealed LSE extending from the level of the L2 vertebral body to the sacrum. However, LSE was reduced following weight loss due to a stomach ulcer. This case clearly indicated obesity as the cause of LSE. The second case was a nonobese 31-year-old woman with acute excruciating low back pain due to thoracolumbar fascia strain. LSE was observed at the level of the L3-L4 vertebral body. Two weeks later, her low back pain and LSE were reduced. This case suggests that the origin of LSE was impairment of the thoracolumbar fascia due to strain. We hypothesize that the mechanism underlying the development of LSE may be lymphatic or interstitial fluid pooling due to disturbance of the lumbar fascia.

Current Overview of Obesity-Induced Lymphedema

Significance: Obesity affects one-third of the U.S. population and lymphedema is a chronic disorder without a cure. The relationship between obesity and lymphedema has important implications for public health. Recent Advances: Extreme obesity can cause lower extremity lymphedema, termed "obesity-induced lymphedema (OIL)." OIL is a form of secondary lymphedema that may occur once an individual's body mass index (BMI) exceeds 40. The risk of lymphatic dysfunction increases with elevated BMI and is almost universal once BMI exceeds 60. Patients with OIL also may develop areas of massive localized lymphedema (MLL). Critical Issues: Individuals with OIL are in an unfavorable cycle of weight gain and lymphatic injury. As BMI increases lymphedema worsens, ambulation becomes more difficult, and BMI further rises. The fundamental treatment for OIL is weight loss. Resection of areas of MLL and lower extremity volume reduction are performed when the BMI is lowered to <40 to reduce complications and recurrence. Future Directions: The mechanisms by which obesity causes lymphedema are still being elucidated. Although lymphatic function can improve following weight loss, it is unclear whether lymphedema may be completely reversed.

Repository Describing the Anatomical, Physiological, and Biological Changes in an Obese Population to Inform Physiologically Based Pharmacokinetic Models

Background

Obesity is associated with physiological changes that can affect drug pharmacokinetics. Obese individuals are underrepresented in clinical trials, leading to a lack of evidence-based dosing recommendations for many drugs. Physiologically based pharmacokinetic (PBPK) modelling can overcome this limitation but necessitates a detailed description of the population characteristics under investigation.

Objective

The purpose of this study was to develop and verify a repository of the current anatomical, physiological, and biological data of obese individuals, including population variability, to inform a PBPK framework.

Methods

A systematic literature search was performed to collate anatomical, physiological, and biological parameters for obese individuals. Multiple regression analyses were used to derive mathematical equations describing the continuous effect of body mass index (BMI) within the range 18.5–60 kg/m² on system parameters.

Results

In total, 209 studies were included in the database. The literature reported mostly BMI-related changes in organ weight, whereas data on blood flow and biological parameters (i.e. enzyme abundance) were sparse, and hence physiologically plausible assumptions were made when needed. The developed obese population was implemented in Matlab^® and the predicted system parameters obtained from 1000 virtual individuals were in agreement with observed data from an independent validation obese population. Our analysis indicates that a threefold increase in BMI, from 20 to 60 kg/m², leads to an increase in cardiac output (50%), liver weight (100%), kidney weight (60%), both the kidney and liver absolute blood flows (50%), and in total adipose blood flow (160%).

Conclusion

The developed repository provides an updated description of a population with a BMI from 18.5 to 60 kg/m² using continuous physiological changes and their variability for each system parameter. It is a tool that can be implemented in PBPK models to simulate drug pharmacokinetics in obese individuals.

Lymphedema and Obesity

Lymphedema results from inadequate lymphatic function. Extreme obesity can cause lower extremity lymphedema, termed "obesity-induced lymphedema (OIL)." OIL is a form of secondary lymphedema that may occur once an individual's body mass index (BMI) exceeds 40. The risk of lymphatic dysfunction increases with elevated BMI and is almost universal once BMI exceeds 60. Obesity has a negative impact on lymphatic density in subcutaneous tissue, lymphatic endothelial cell proliferation, lymphatic leakiness, collecting-vessel pumping capacity, and clearance of macromolecules. Lymphatic fluid unable to be taken up by lymphatic vessels results in increased subcutaneous adipose deposition, fibrosis, and worsening obesity. Individuals with OIL are in an unfavorable cycle of weight gain and lymphatic injury. The fundamental treatment for OIL is weight loss.

Quality of Life Predictors in Patients With Melanoma: A Machine Learning Approach

Health related quality of life (HRQoL) is an important recognized health outcome for cancer treatments, but also disease course with slower recovery and increased morbidity. These issues are of implication in melanoma, which maintains a risk of disease progression for many years after diagnosis. This study aimed to explore and weigh factors in the perception of the quality of life and possible relationships with demographic–clinical characteristics in people with melanoma via a machine learning approach. In this observational study, patients with melanoma, without metastatic disease, were recruited from January 2020 to December 2021 with a follow-up of at least one year. Demographic variables and clinics were collected, and the 12-Item Short-Form Health Survey (SF-12) was adopted as the physical and mental aspects of the Health-Related Quality of Life (HRQoL) measure. All the variables were processed in a random forest model to weigh at each node of each tree of this machine learning regression model, their actual weight in SF-12 score. We included 203 melanoma patients, mean aged 59.25 ± 15.1 years: 56 (27%) affecting the upper limbs and 147 (73%) affecting the trunk. The model of 142 patients with no missing value, generating 92 trees (MSE = 0.45, R2 of 0.78), reported that the lesion site was the most influencing variable on HRQoL based on the decrease in Gini impurity in variable weighing at each node intersection in forest generation. In this scenario, we built two distinct models for lesion sites and demonstrated that the variable that most influenced the quality of life in upper limb melanoma was lymphedema, while BMI was in the trunk. Given these results, random forest regressions could play a crucial role in the clinical and rehabilitation approach. The machine-learning model for detecting the HRQoL predictor in melanoma patients indicates that the experienced lymphedema and BMI may influence the HRQoL perception. This study suggests that the prevention and treatment of lymphedema and bodyweight reduction might improve the quality of life in melanoma.

Lymphatic Collecting Vessel: New Perspectives on Mechanisms of Contractile Regulation and Potential Lymphatic Contractile Pathways to Target in Obesity and Metabolic Diseases

Obesity and metabolic syndrome pose a significant risk for developing cardiovascular disease and remain a critical healthcare challenge. Given the lymphatic system's role as a nexus for lipid absorption, immune cell trafficking, interstitial fluid and macromolecule homeostasis maintenance, the impact of obesity and metabolic disease on lymphatic function is a burgeoning field in lymphatic research. Work over the past decade has progressed from the association of an obese phenotype with Prox1 haploinsufficiency and the identification of obesity as a risk factor for lymphedema to consistent findings of lymphatic collecting vessel dysfunction across multiple metabolic disease models and organisms and characterization of obesity-induced lymphedema in the morbidly obese. Critically, recent findings have suggested that restoration of lymphatic function can also ameliorate obesity and insulin resistance, positing lymphatic targeted therapies as relevant pharmacological interventions. There remain, however, significant gaps in our understanding of lymphatic collecting vessel function, particularly the mechanisms that regulate the spontaneous contractile activity required for active lymph propulsion and lymph return in humans. In this article, we will review the current findings on lymphatic architecture and collecting vessel function, including recent advances in the ionic basis of lymphatic muscle contractile activity. We will then discuss lymphatic dysfunction observed with metabolic disruption and potential pathways to target with pharmacological approaches to improve lymphatic collecting vessel function.

Lymphatic Valve Dysfunction in Western Diet-Fed Mice: New Insights Into Obesity-Induced Lymphedema

A two-way connection between obesity and lymphatic dysfunction has now been established. Clinical studies have demonstrated that obesity significantly increases the risk for developing secondary lymphedema. Using animal-models, obesity and metabolic syndrome have been linked to different aspects of lymphatic structural abnormalities and lymphatic dysfunction, including impaired contractility, impaired flow-mediated responses, impaired fluid transport, as well as increased permeability, and abnormal dendritic cell migration among others. Dysfunction of lymphatic valves is a main form of lymphatic dysfunction, known to result in severe edematous phenotypes; however, the extent of lymphatic valve deficiency in secondary lymphedema, including obesity-induced lymphedema, remains unknown. Therefore, the aims of the present study were 1) to determine whether western diet-induced obesity results in lymphatic valve dysfunction, and 2) to determine whether lymphatic valve dysfunction in western diet-induced obesity results from the diet itself, or as a consequence of the metabolic alterations induced by the diet. First, we quantitatively assessed and compared valve function in isolated popliteal and mesenteric collecting lymphatic vessels from control and western diet-induced obese C57BL/6J (WT) mice. Feeding a western diet for 14 weeks induced obesity and elevated plasma glucose and cholesterol levels when compared to controls. The function of lymphatic valves in popliteal lymphatics was not affected by diet-induced obesity; however, significant back-leak of pressure was observed in mesenteric lymphatic valves. Dysfunctional, leaky valves from obese animals also required significantly higher adverse pressure to trigger valve closure. Importantly, when subjected to treatment with a western diet, globally deficient PAI-1 mice were significantly protected against metabolic dysfunction and displayed fully functional, competent mesenteric lymphatic valves. In conclusion, our findings show for the first time that, in association with the metabolic alterations induced by the western diet, lymphatic valve dysfunction can be a critical component of obesity-induced lymphedema.

Lymphatic Collecting Vessels in Health and Disease: A Review of Histopathological Modifications in Lymphedema

Secondary lymphedema of the extremities affects millions of people in the world as a common side effect of oncological treatments with heavy impact on every day life of patients and on the health care system. One of the surgical techniques for lymphedema treatment is the creation of a local connection between lymphatic vessels and veins, facilitating drainage of lymphatic fluid into the circulatory system. Successful results, however, rely on using a functional vessel for the anastomosis, and vessel function, in turn, depends on its structure. The structure of lymphatic collecting vessels changes with the progression of lymphedema. They appear initially dilated by excess interstitial fluid entered at capillary level. The number of lymphatic smooth muscle cells in their media then increases in the attempt to overcome the impaired drainage. When lymphatic muscle cells hyperplasia occurs at the expenses of the lumen, vessel patency decreases hampering lymph flow. Finally, collagen fiber accumulation leads to complete occlusion of the lumen rendering the vessel unfit to conduct lymph. Different types of vessels may coexist in the same patient but usually the distal part of the limb contains less affected vessels that are more likely to perform efficient lymphatic–venular anastomosis. Here we review the structure of the lymphatic collecting vessels in health and in lymphedema, focusing on the histopathological changes of the lymphatic vessel wall based on the observations on segments of the vessels used for lymphatic–venular anastomoses.

Multiple aspects of lymphatic dysfunction in an ApoE -/- mouse model of hypercholesterolemia

Introduction: Rodent models of cardiovascular disease have uncovered various types of lymphatic vessel dysfunction that occur in association with atherosclerosis, type II diabetes and obesity. Previously, we presented in vivo evidence for impaired lymphatic drainage in apolipoprotein E null (ApoE ^-/- ) mice fed a high fat diet (HFD). Whether this impairment relates to the dysfunction of collecting lymphatics remains an open question. The ApoE ^-/- mouse is a well-established model of cardiovascular disease, in which a diet rich in fat and cholesterol on an ApoE deficient background accelerates the development of hypercholesteremia, atherosclerotic plaques and inflammation of the skin and other tissues. Here, we investigated various aspects of lymphatic function using ex vivo tests of collecting lymphatic vessels from ApoE ^+/+ or ApoE ^-/- mice fed a HFD. Methods: Popliteal collectors were excised from either strain and studied under defined conditions in which we could quantify changes in lymphatic contractile strength, lymph pump output, secondary valve function, and collecting vessel permeability. Results: Our results show that all these aspects of lymphatic vessel function are altered in deleterious ways in this model of hypercholesterolemia. Discussion: These findings extend previous in vivo observations suggesting significant dysfunction of lymphatic endothelial cells and smooth muscle cells from collecting vessels in association with a HFD on an ApoE-deficient background. An implication of our study is that collecting vessel dysfunction in this context may negatively impact the removal of cholesterol by the lymphatic system from the skin and the arterial wall and thereby exacerbate the progression and/or severity of atherosclerosis and associated inflammation.

Elevated magnetic resonance imaging measures of adipose tissue deposition in women with breast cancer treatment-related lymphedema

PURPOSE

Breast cancer treatment-related lymphedema (BCRL) is a common co-morbidity of breast cancer therapies, yet factors that contribute to BCRL progression remain incompletely characterized. We investigated whether magnetic resonance imaging (MRI) measures of subcutaneous adipose tissue were uniquely elevated in women with BCRL.

METHODS

MRI at 3.0 T of upper extremity and torso anatomy, fat and muscle tissue composition, and T₂ relaxometry were applied in left and right axillae of healthy control (n = 24) and symptomatic BCRL (n = 22) participants to test the primary hypothesis that fat-to-muscle volume fraction is elevated in symptomatic BCRL relative to healthy participants, and the secondary hypothesis that fat-to-muscle volume fraction is correlated with MR relaxometry of affected tissues and BCRL stage (significance criterion: two-sided p < 0.05).

RESULTS

Fat-to-muscle volume fraction in healthy participants was symmetric in the right and left sides (p = 0.51); in BCRL participants matched for age, sex, and BMI, fat-to-muscle volume fraction was elevated on the affected side (fraction = 0.732 ± 0.184) versus right and left side in controls (fraction = 0.545 ± 0.221, p < 0.001). Fat-to-muscle volume fraction directly correlated with muscle T₂ (p = 0.046) and increased with increasing level of BCRL stage (p = 0.041).

CONCLUSION

Adiposity quantified by MRI is elevated in the affected upper extremity of women with BCRL and may provide a surrogate marker of condition onset or severity.

CLINICAL TRIAL

NCT02611557.

Adipose Tissue and Biological Factors. Possible Link between Lymphatic System Dysfunction and Obesity

The World Health Organization (WHO) has recognised obesity as one of the top ten threats to human health. Obesity is not only a state of abnormally increased adipose tissue in the body, but also of an increased release of biologically active metabolites. Moreover, obesity predisposes the development of metabolic syndrome and increases the incidence of type 2 diabetes (T2DM), increases the risk of developing insulin resistance, atherosclerosis, ischemic heart disease, polycystic ovary syndrome, hypertension and cancer. The lymphatic system is a one-directional network of thin-walled capillaries and larger vessels covered by a continuous layer of endothelial cells that provides a unidirectional conduit to return filtered arterial and tissue metabolites towards the venous circulation. Recent studies have shown that obesity can markedly impair lymphatic function. Conversely, dysfunction in the lymphatic system may also be involved in the pathogenesis of obesity. This review highlights the important findings regarding obesity related to lymphatic system dysfunction, including clinical implications and experimental studies. Moreover, we present the role of biological factors in the pathophysiology of the lymphatic system and we propose the possibility of a therapy supporting the function of the lymphatic system in the course of obesity.

The Impact of High-Fat Diet and Restrictive Feeding on Natural Killer Cells in Obese-Resistant BALB/c Mice

Background: The association of obesity and an increased risk for severe infections and various cancer types is well-described. Natural killer (NK) cells are circulating lymphoid cells and promoters of the immune response toward viruses and malignant cells. As demonstrated in previous studies the phenotype and functionality of NK cells is impaired in obesity. So far, the majority of animal studies were exclusively performed using ad libitum feeding regimes and it remained unclear whether NK cell alterations are mediated by obesity-associated immunological changes or by direct effects of the dietary composition. Therefore, the aim of the present study was to characterize NK cells in the peripheral blood of obese-resistant BALB/c mice supplied a normal-fat diet (NFD) or high-fat diet (HFD), ad libitum or in a restrictive manner. Methods: Twenty-eight BALB/c-mice were fed a NFD or HFD either ad libitum or in a restrictive feeding regime with 90% of the mean daily diet supply of the corresponding ad libitum group (each group n = 7). Blood and visceral adipose tissue were collected for flow cytometric analysis, analysis of plasma cytokine concentrations by multiplex immunoassay and real-time RT-PCR analyses. For statistical analyses two-way ANOVA with the factors "feeding regime" and "diet" was performed followed by a post-hoc Tukey's multiple comparison test and to compare means of the four mouse groups. Results: Ad libitum-feeding of a HFD in BALB/c mice has no influence on body weight gain, visceral fat mass, plasma cytokine concentrations, immune cell populations as well as the number, frequency and phenotype of NK cells. In contrast, restrictive feeding of a HFD compared to NFD led to significantly higher body weights, visceral fat mass and plasma interferon-γ concentrations which was associated with changes in the frequencies of granulocytes and NK cell subsets as well as in the surface expression of NK cell maturation markers. Conclusion: Results demonstrate for the first time that HFD-induced alterations in NK cells are consequences of the obese associated immunological profile rather than a direct effect of the dietary composition. These data can help to clarify the increased risk for cancer and severe infections in obesity.

Biology of Lymphedema

Simple Summary

Lymphedema is a chronic, debilitating disease of the lymphatic vasculature. Although several reviews focus on the anatomy and physiology of the lymphatic system, this review provides an overview of the lymphatic vasculature and, moreover, of lymphatic system dysfunction and lymphedema. Further, we aim at advancing the knowledge in the area of lymphatic system function and how dysfunction of the lymphatic system—as seen in lymphedema—affects physiological systems, such as the cardiovascular system, and how those might be modulated by lymphedema therapy.

Abstract

This narrative review portrays the lymphatic system, a poorly understood but important physiological system. While several reviews have been published that are related to the biology of the lymphatic system and lymphedema, the physiological alternations, which arise due to disturbances of this system, and during lymphedema therapy, are poorly understood and, consequently, not widely reported. We present an inclusive collection of evidence from the scientific literature reflecting important developments in lymphedema research over the last few decades. This review aims at advancing the knowledge on the area of lymphatic system function as well as how system dysfunction, as seen in lymphedema, affects physiological systems and how lymphedema therapy modulates these mechanisms. We propose that future studies should aim at investigating, in-detail, aspects that are related to fluid regulation, hemodynamic responses, and endothelial and/or vascular changes due to lymphedema and lymphedema therapy.

Outcomes of Vascularized Lymph Node Transplantation for Treatment of Lymphedema

BACKGROUND

A growing body of evidence supports the efficacy of surgical treatments for lymphedema. This study reports the outcomes of vascularized lymph node transplantation (VLNT) for the treatment of patients with lymphedema compared with maximal conservative treatment alone.

STUDY DESIGN

Consecutive patients undergoing VLNT to treat primary and secondary lymphedema affecting the upper or lower extremities were included. All patients were optimized preoperatively with conservative therapy. Demographic and treatment information was collected, and outcomes data were electronically captured prospectively; descriptive statistics were performed.

RESULTS

There were 134 patients included that had achieved maximal reductions by conservative therapy preoperatively. This series included jejunal mesenteric (n = 25), groin (n = 43), lateral thoracic (n = 31), omental or right gastroepiploic (n = 21), and submental (n = 14) VLN flaps. At 24 months postoperatively, there were significant reductions in limb volume change (mean [SD] 45.7% [8.7%]; p = 0.002) LDex score (mean [SD] 59.8% [8.7%]; p < 0.001), Lymphedema Life Impact Scale score (mean [SD] 61.6% [5.9]; p < 0.001), and cellulitis episodes (97.9%; p < 0.001). At 3 and 6 months postoperatively, limb volume change was significantly greater for the upper than the lower extremity, otherwise outcomes were similar. There were no flap losses and overall outcomes were similar between the different VLN flap types.

CONCLUSIONS

Treatment of lymphedema using VLNT resulted in progressive, significant reductions in limb volume, bioimpedance spectroscopy measurements of extracellular fluid, and episodes of cellulitis, with improved patient-reported outcomes and limb function measures compared with maximal conservative therapy alone. The complication rate was low and there were no significant outcomes differences between the VLNT types.

Lymphstase und Fettgewebshypertrophie – Pathophysiologische Zusammenhänge und therapeutische Optionen

Angeborene oder erworbene, iatrogene, traumatische oder postinfektiöse Störungen des Lymphabflusses führen aufgrund der Lymphstase im Laufe der Zeit zu Gewebeveränderungen wie Fibrosierung und vermehrter lokaler Fettgewebebildung. Häufig kommt es hierdurch zu einer extremen Volumenzunahme der betroffenen Extremität, die nicht durch das Lymphödem allein, sondern vor allem durch die massive Fettgewebshypertrophie bedingt ist. Lymphgefäße und Lymphknoten sind immer in Fettgewebe eingebettet. Dieses perilymphatische Fettgewebe ist essenziell für die lymphatische wie auch immunologische Funktion des Lymphsystems, da das Lymphsystem Fettsäuren als primäre Energiequelle nützt. Kommt es nach Lymphadenektomie und/oder Unterbrechung von Lymphgefäßen zur Lymphstase in der betroffenen Extremität, signalisiert diese einen gesteigerten Energiebedarf für die notwendige Immunantwort und die chronische Inflammation verursacht eine Überstimulation der Fettgewebsproliferation, um ausreichend Energie zur Verfügung stellen zu können. In der Folge kommt es zu weiteren pathophysiologischen Veränderungen, die die Drainagefunktion und damit die Lymphstase weiter verschlechtern. Es hat sich ein Circulus vitiosus aus Lymphstase, Fettgewebsproliferation und Fibrosierung entwickelt.

Da die komplexe Entstauungstherapie diesen Zustand allein nicht wesentlich verbessern kann, kommen therapeutisch zusätzliche gewebereduzierende operative Verfahren, in erster Linie die Liposuktion, ggf. in Kombination mit mikrochirurgischen Operationstechniken, zum Einsatz.

Medicine and Phlebolymphology: Time to Change?

Biomedical science is undergoing a reappraisal of its scientific advancement process and of the related healthcare management. Progress in medicine should combine improvements of knowledge, efficacy, and safety of diagnostic/therapeutic procedures, with adequate cost-effectiveness profiles. This narrative review is aimed at assessing in medicine, more specifically in phlebology and lymphology: (a) scientific literature possible biases, (b) the level of evidence, comprehensiveness, and cost-effectiveness of the main therapeutic options, and (c) the possible contribution of integrative and translational medicine. Current medical research may have cognitive biases, or industry-tied influences, which impacts clinical practice. Some reductionism, with an increasing use of drugs and technology, often neglecting the understanding and care of the root causative pathways of the diseases, is affecting biomedical science as well. Aging brings a relevant burden of chronic degenerative diseases and disabilities, with relevant socio-economic repercussions; thus, a major attention to cost-effectiveness and appropriateness of healthcare is warranted. In this scenario, costly and innovative but relatively validated therapies may tend to be adopted in venous and lymphatic diseases, such as varicose veins, leg venous ulcer, post-thrombotic syndrome, pelvic congestion syndrome, and lymphedema. Conversely, a more comprehensive approach to the basic pathophysiology of chronic venous and lymphatic insufficiency and the inclusion of pharmacoeconomics analyses would benefit overall patients' management. Erroneous lifestyle and nutrition, together with chronic stress-induced syndromes, significantly influence chronic degenerative phlebo-lymphatic diseases. The main active epigenetic socio-biologic factors are obesity, dysfunctions of musculo-respiratory-vascular pumps, pro-inflammatory nutrition, hyperactivation of stress axis, and sedentarism. An overall critical view of the scientific evidence and innovations in phebolymphology could be of help to improve efficacy, safety, and sustainability of current practice. Translational and integrative medicine may contribute to a patient-centered approach. Conversely, reductionism, eminence/reimbursement-based decisional processes, patients' lack of education, industry-influenced science, and physician's improvable awareness, may compromise efficacy, safety, appropriateness, and cost-effectiveness of future diagnostic and therapeutic patterns of phlebology and lymphology.

Lymphatic Transport Efficiency Determines Metastatic Potential of Cutaneous Melanoma

Background

In staging patients with clinical stage I-II melanoma, the sentinel lymph node (SLN) is the most important prognostic indicator; however, the false negative rate of SLN biopsy (SLNB) is 15%.

Methods

Nine patients with clinical Stage I-II melanoma underwent SLNB with repeated intraoperative radiotracer measurements to determine lymphatic transport efficiency (LTE), which was correlated with clinicopathologic data.

Results

LTE demonstrated the potential to predict SLN status. LTE in patients with occult nodal metastasis is 40 times faster than those with negative SLNBs. There was no confounding of LTE by clinicopathologic factors.

Significance:

LTE may be a novel biomarker for metastasis, with transformative potential for personalized precision diagnostics of early-stage disease and improved patient survival.

Implications of cellular metabolism for immune cell migration

Cell migration is an essential, energetically demanding process in immunity. Immune cells navigate the body via chemokines and other immune mediators, which are altered under inflammatory conditions of injury or infection. Several factors determine the migratory abilities of different types of immune cells in diverse contexts, including the precise co-ordination of cytoskeletal remodelling, the expression of specific chemokine receptors and integrins, and environmental conditions. In this review, we present an overview of recent advances in our understanding of the relationship of each of these factors with cellular metabolism, with a focus on the spatial organization of glycolysis and mitochondria, reciprocal regulation of chemokine receptors and the influence of environmental changes.

Iron Metabolism in Obesity and Metabolic Syndrome

Obesity is an excessive adipose tissue accumulation that may have detrimental effects on health. Particularly, childhood obesity has become one of the main public health problems in the 21st century, since its prevalence has widely increased in recent years. Childhood obesity is intimately related to the development of several comorbidities such as nonalcoholic fatty liver disease, dyslipidemia, type 2 diabetes mellitus, non-congenital cardiovascular disease, chronic inflammation and anemia, among others. Within this tangled interplay between these comorbidities and associated pathological conditions, obesity has been closely linked to important perturbations in iron metabolism. Iron is the second most abundant metal on Earth, but its bioavailability is hampered by its ability to form highly insoluble oxides, with iron deficiency being the most common nutritional disorder. Although every living organism requires iron, it may also cause toxic oxygen damage by generating oxygen free radicals through the Fenton reaction. Thus, iron homeostasis and metabolism must be tightly regulated in humans at every level (i.e., absorption, storage, transport, recycling). Dysregulation of any step involved in iron metabolism may lead to iron deficiencies and, eventually, to the anemic state related to obesity. In this review article, we summarize the existent evidence on the role of the most recently described components of iron metabolism and their alterations in obesity.