Regulation of adipogenesis by lymphatic fluid stasis: part II. Expression of adipose differentiation genes

The impact of obesity on chronic oedema/lymphoedema of the leg - an international multicenter cross-sectional study (LIMPRINT)

BACKGROUND/OBJECTIVES

Obesity and chronic oedema/lymphoedema are two distinct but related conditions, rarely investigated together. The aim was to study the impact of increased weight on chronic oedema and related factors.

SUBJECTS/METHODS

A cross-sectional study, 38 centers, nine countries. Patients with clinically confirmed chronic oedema/lymphoedema of the leg were included. Weight category was estimated as: normal weight (BMI 20-30), class I-II obesity (BMI 30-40), or class III obesity (BMI > 40). Factors were tested for an association with increased weight, using a multivariable model.

RESULTS

A total of 7397 patients were included; 43% with normal weight, 36% class I-II obesity and 21% class III obesity. Increased weight was associated with more advanced stages of chronic oedema (ISL stage III; the most advanced form); affecting 14% in normal weight, 18% class I-II obesity and 39% class III obesity (p < 0.001). Ten factors were independently associated with increased weight: diabetes (OR 2.4), secondary lymphoedema (OR 2.7), cellulitis/erysipelas within 12 months (OR 1.2), bilateral lymphoedema (OR 3.6), compression therapy (OR 2.1), increased swelling duration (1-2 years OR 1.3, 2-5 years OR 2.5, 5-10 years OR 3.6, >10 years OR 3.5) decreased mobility (walking with aid OR 1.9, being chair bound OR 1.2) and age (reference<45 years; 45-64 years OR 1.5, 75-84 years OR 0.6, 85+ years OR 0.2). Increased weight was associated with a lower presentation of peripheral arterial disease (OR 0.7) and poorer chronic oedema control (OR 0.8). Patients with obesity had lower function, appearance and more severe symptoms (LYMQOL) and lower quality of life (EuroQol).

CONCLUSIONS

Obesity negatively impacts chronic oedema, leading to more advanced stages. Achieving good control of swelling with compression is more difficult in these patients. Increased awareness of chronic oedema/lymphoedema as a complication of obesity is important for early detection and for developing effective strategies to prevent and manage them.

Molecular pathophysiology of secondary lymphedema

Lymphedema occurs as a result of lymphatic vessel damage or obstruction, leading to the lymphatic fluid stasis, which triggers inflammation, tissue fibrosis, and adipose tissue deposition with adipocyte hypertrophy. The treatment of lymphedema is divided into conservative and surgical approaches. Among surgical treatments, methods like lymphaticovenular anastomosis and vascularized lymph node transfer are gaining attention as they focus on restoring lymphatic flow, constituting a physiologic treatment approach. Lymphatic endothelial cells form the structure of lymphatic vessels. These cells possess button-like junctions that facilitate the influx of fluid and leukocytes. Approximately 10% of interstitial fluid is connected to venous return through lymphatic capillaries. Damage to lymphatic vessels leads to lymphatic fluid stasis, resulting in the clinical condition of lymphedema through three mechanisms: Inflammation involving CD4+ T cells as the principal contributing factor, along with the effects of immune cells on the VEGF-C/VEGFR axis, consequently resulting in abnormal lymphangiogenesis; adipocyte hypertrophy and adipose tissue deposition regulated by the interaction of CCAAT/enhancer-binding protein α and peroxisome proliferator-activated receptor-γ; and tissue fibrosis initiated by the overactivity of Th2 cells, leading to the secretion of profibrotic cytokines such as IL-4, IL-13, and the growth factor TGF-β1. Surgical treatments aimed at reconstructing the lymphatic system help facilitate lymphatic fluid drainage, but their effectiveness in treating already damaged lymphatic vessels is limited. Therefore, reviewing the pathophysiology and molecular mechanisms of lymphedema is crucial to complement surgical treatments and explore novel therapeutic approaches.

Progression of fluid infiltration on non-contrast magnetic resonance imaging in breast cancer-related lymphedema: A comparative analysis with indocyanine green lymphography

BACKGROUND

Non-contrast magnetic resonance imaging (NMRI) has been reported as valuable for the assessment of lymphedema. However, the correlation between NMRI findings and indocyanine green lymphography (ICG-L) findings remains elusive.

METHODS

This single-center retrospective study included 26 patients diagnosed with breast cancer-related lymphedema. We examined the prevalence of fluid infiltration in eight regions of the upper extremity, the type of fluid distribution, and the dominant segment of edema on NMRI in comparison to the ICG-L stage. Statistical analysis was performed using the Cochran-Armitage trend test, Spearman's rank correlation test, and Fisher's exact test.

RESULTS

The regional fluid infiltration significantly increased with the progression of the ICG-L stage (hand, forearm, elbow, and upper arm: p = 0.003, <0.001, <0.001, and <0.001, respectively). The fluid distribution significantly advanced with the progression of the ICG-L stage as follows (rs = 0.80; p < 0.001): no edema in ICG-L stage 0, edema in either the hand or elbow in ICG-L stage I, edemas in both the elbow and hand in ICG-L stage II, three segmental edemas centered on the forearm or elbow in ICG-L stage III, and edema encompassing the entire upper limb in ICG-L stage IV-V. Additionally, the dominant segment of edema tended to shift from the hand to the elbow and further to the forearm as the ICG-L stage progressed (p < 0.001).

CONCLUSIONS

Fluid infiltration observed on NMRI exhibited distinct patterns with the progression of the ICG-L stage. We believe that anatomical information regarding fluid distribution would potentially contribute to optimizing surgical efficacy.

GLP-1 receptor agonist as an effective treatment for breast cancer-related lymphedema: a case report

Introduction

Lymphedema is a major public health issue for many women undergoing breast cancer treatment. Although weight loss has been reported to be beneficial in the treatment of lymphedema, no studies to date have examined the use of GLP-1RAs for the treatment of secondary lymphedema. This case report describes a patient who experienced significant resolution of her breast cancer-related lymphedema after initiation of a GLP-1RA for weight loss.

Main symptoms and/or important clinical findings

Nine months postoperatively the patient developed arm swelling and disability. While on adjuvant chemo and hormonal therapy, her weight increased dramatically and peaked 4 years later. Corresponding to her weight gain was significant worsening of her symptoms.

The main diagnoses therapeutic interventions and outcomes

Due to adjuvant cancer-related weight gain and inability to lose weight with diet and exercise, she was referred for evaluation and diagnosed with lymphedema. The patient started treatment with a Glucagon-like peptide 1 receptor agonist and lost 24% of her body weight over the next 13 months. The improvement in her lymphedema mirrored her weight loss. Her limb volume difference dropped from 10.3% down to 3.4% and she no longer required a compression garment. Her imaging demonstrated return of lymphatic pumping and she experienced a significant improvement in quality of life, assessed by a validated lymphedema-specific patient reported outcome (PROM). She remains on hormonal therapy, no longer needs compression and is back to regular exercise without impairment.

Conclusions

GLP-1 RAs provide a potential medical option for many patients struggling with weight gain and lymphedema. We have observed by all objective measures a significant reduction in lymphedema and the elimination of compression in the case presented as a direct result of GLP-1 RA. This may also reduce a patient's BMI to the point where they become a good candidate for lymphovenous bypass or vascularized lymph node transplant when indicated.

Liposuction for Advanced Lymphedema in a Multidisciplinary Team Setting in Australia: 5-Year Follow-Up

BACKGROUND

Liposuction for International Society of Lymphology late stage 2 or 3 limb lymphedema is an established surgical option to remove excessive adipose tissue deposition and has been performed in Australia since 2012 at the Australian Lymphoedema Education, Research, and Treatment (ALERT) Program of Macquarie University.

METHODS

Between May of 2012 and May of 2017, 72 patients with unilateral primary or secondary lymphedema of the arm or leg underwent suction-assisted lipectomy using the Brorson protocol. This prospective study presents 59 of these patients who had consented to research with a 5-year follow-up.

RESULTS

Of the 59 patients, 54 (92%) were women, 30 (51%) had leg lymphedema, and 29 (49%) had arm lymphedema. For patients with arm lymphedema, the median preoperative volume difference between the lymphedematous and the contralateral arm was 1061 mL, which was reduced to 79 mL 1 year after surgery and to 22 mL 5 years after surgery. For patients with leg lymphedema, the median preoperative volume difference was 3447 mL, which was reduced to 263 mL 1 year after surgery but increased to 669 mL 5 years after surgery.

CONCLUSION

Suction-assisted lipectomy is a long-term option for the management of selected patients with International Society of Lymphology late stage 2 or 3 limb lymphedema when conservative management can offer no further improvement.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

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.

Complete Reduction of Leg Lymphedema after Liposuction: A 5-Year Prospective Study in 67 Patients without Recurrence

BACKGROUND

Lymphedema leads to adipose tissue deposition that cannot be removed using conservative methods. Previous studies have shown a complete reduction in excess volume in limbs with lymphedema when treated with liposuction and controlled compression therapy (CCT). We present the long-term outcomes of all patients treated with liposuction and CCT for lower extremity lymphedema (LEL) who were followed up for 5 years.

METHODS

Sixty-seven LEL patients underwent liposuction and CCT. Thirty-six patients had primary lymphedema and 31 patients had secondary lymphedema. The outcomes included excess leg volume over a follow-up period of 5 years. Any association between patient characteristics and treatment outcomes was analyzed.

RESULTS

The preoperative excess volume prior was 3515 mL [interquartile range (IQR): 2225-5455 mL], and the volume ratio to the unaffected leg was 1.35 (IQR: 1.25-1.53). One year after treatment, the excess volume decreased by 101% (IQR: 84-116). The decrease in excess volume continued during the 5-year follow-up, and at the end of the study, the excess volume had decreased by 115% (IQR: 98-124). No major complications were noted.

CONCLUSIONS

Liposuction and CCT are safe and effective procedures for removing excess adipose tissue and normalizing the leg volume in patients with late-stage LEL. When no satisfactory results are obtained with conservative methods, such as complex decongestive therapy, and there is no or minimal pitting on limb examination, excess adipose tissue is present, and liposuction can be considered.

Lipedema: What we don't know

BACKGROUND

Lipedema is a loose connective tissue disease characterized by a disproportionate accumulation of adipose tissue in the limbs of women. Despite its incidence of 10-20%, lipedema is often underdiagnosed and misdiagnosed.

OBJECTIVES

This review aims to outline current, available evidence regarding this enigmatic syndrome and gives a synopsis of the subjects that are still unknown.

MATERIALS AND METHODS

PubMed and Embase searches were conducted to identify relevant articles on lipedema pathophysiology, clinical presentation, diagnosis, and treatment.

RESULTS

Lipedema can be considered a disease of the adipocytes or a circulatory disorder of the lymphatics. The relationship between lymphatics and adipose tissue remains controversial. The clinical distinction between lipedema, lymphedema, phlebolymphedema, and lipolymphedema can be difficult. Diagnoses often coexist, further complicating the diagnosis of lipedema, which is currently made on clinical grounds alone. The value of diagnostic imaging studies is unclear. Liposuction appears to be an effective treatment and significantly improves symptoms.

CONCLUSION

Diagnosing lipedema remains a challenge due to its heterogeneous presentation, co-existing diseases, and lack of objective diagnostic imaging. Further directions for research include the effect of excess skin resection surgery on lymphatic drainage.

Body mass index increases the risk of breast cancer-related lymphedema at 6-18 months after surgery: a retrospective study

PURPOSE

Breast cancer-related lymphedema (BCRL) is an incurable complication occurring after breast cancer treatment. The influence of obesity/overweight on the development of BCRL at different points after surgery was seldom verified. We aimed to determine the cut-off BMI/weight value associated with an increased risk of BCRL at different postoperative time in Chinese breast cancer survivors.

METHODS

Patients who underwent breast surgery plus axillary lymph node dissection (ALND) were retrospectively evaluated. Disease and treatment characteristics of participants were collected. BCRL was diagnosed by circumference measurements. Univariate and multivariable logistic regression was used to assess the relationship of lymphedema risk with BMI/weight and other disease- and treatment-related factors.

RESULTS

518 patients were included. Lymphedema occurred more frequently among breast cancer patients with preoperative BMI ≥ 25 kg/m² (37.88%) than among those with preoperative BMI < 25 kg/m²(23.32%), with significant differences at 6-12 and 12-18 months after surgery (χ² = 23.183, P = 0.000; χ² = 5.279, P = 0.022). By multivariable logistics analysis, preoperative BMI ≥ 30 kg/m² presented a significantly greater risk of lymphedema than a preoperative BMI < 25 kg/m² (OR [95% CI] = 2.928 [1.565, 5.480]). Other factors, including radiation (breast/chest wall + axilla vs. none: OR [95% CI] = 3.723[2.271-6.104]), was an independent risk factor for lymphedema.

CONCLUSIONS

Preoperative obesity was an independent risk factor for BCRL in Chinese breast cancer survivors, and a preoperative BMI ≥ 25 kg/m² indicated greater likelihood of lymphedema development within 6-18 months postoperatively.

Clinical Impact of Severe Obesity in Patients with Lymphoedema

OBJECTIVE

With the rate of obesity increasing worldwide, patients with lymphoedema with and without a concomitant diagnosis of severe obesity (SO) were compared in regard to their baseline demographics, health related characteristics, treatment plans, and patient outcomes.

METHODS

This was a retrospective observational cohort study. The IBM MarketScan database was examined (2013 - 2019) for patients with a new diagnosis of lymphoedema. Of 60 284 patients with lymphoedema identified, 6 588 had SO defined by a body mass index > 40 kg/m2. The demographics and other characteristics of SO were compared with patients with lymphoedema without SO.

RESULTS

SO and lymphoedema diagnosis increased two fold from 2013 to 2019. The lymphoedema SO+ group was younger (57.8 vs. 60.8 years, p < .001) and with a higher proportion of men (37.7% vs. 24.9%, p < .001) than the lymphoedema SO- group. More comorbidities were observed in the lymphoedema SO+ group than the lymphoedema SO- group: diabetes 46.0% vs. 24.9 % (p < .001), heart failure 18.3% vs. 7.4% (p < .001), hypertension 75.0% vs. 47.6% (p < .001), and renal disease 24.8% vs. 11.9% (p < .001). Use of diuretics in the lymphoedema SO+ group was greater: 57.6% vs. 38.0% (p < .001). Patients with lymphoedema SO+ had higher risk of cellulitis: 34.5% vs. 13.5% (p < .001). Specific lymphoedema treatment was given more often to lymphoedema SO-: 66.3% vs. 64.3% (p = .003). This was significant for manual lymphatic drainage (46.6% vs. 40.0%; p < .001) and physical therapy (55.4% vs. 51.6%; p<.001), but not for compression garments (18.2% vs. 17.7%; p = .38). However, more patients with lymphoedema SO+ received pneumatic compression device treatment: 20.9% vs. 13.7% (p < .001).

CONCLUSION

There was an increase in SO associated lymphoedema. Patients with lymphoedema SO+ have over a two and half fold increase in cellulitis incidence, with a significant increase in medical resource use and cost. Despite this, patients with lymphoedema and SO receive less specific therapy such as compression, which has proven to reduce cellulitis incidence.

Comparison of the Effectiveness of Liposuction for Lower Limb versus Upper Limb Lymphedema

OBJECTIVE

Liposuction is the most frequently performed debulking procedure in patients with lymphedema. However, it remains uncertain whether liposuction is equally effective for upper extremity lymphedema (UEL) and lower extremity lymphedema (LEL). In this study, we retrospectively compared the effectiveness of liposuction according to whether it was performed for LEL or UEL, and identified factors associated with outcomes.

MATERIALS AND METHODS

All patients had been treated at least once by lymphovenous anastomosis or vascularized lymphatic transplant before liposuction but without sufficient volume reduction. The patients were divided into an LEL group and a UEL group, and then subdivided further according to whether they completed their planned compression therapy into an LEL compliance group, an LEL non-compliance group, a UEL compliance group, and a UEL non-compliance group. The reduction rates in LEL (REL) and in UEL (REU) were compared between the groups.

RESULTS

In total, 28 patients with unilateral lymphedema were enrolled (LEL compliance group, n = 12; LEL non-compliance group, n = 6; UEL compliance group, n = 10; UEL non-compliance group, n = 0). The non-compliance rate was significantly higher in the LEL group than in the UEL group (p = 0.04). REU was significantly higher than REL (100.1 ± 37.3% vs. 59.3 ± 49.4%; p = 0.03); however, there was no significant difference between REL in the LEL compliance group (86 ± 31%) and REU in the UEL group (101 ± 37%) (p = 0.32).

CONCLUSION

Liposuction seems to be more effective in UEL than in LEL, probably because the compression therapy required for management after liposuction is easier to implement for UEL. The lower pressure and smaller coverage area required for postoperative management after liposuction in the upper limb may explain why liposuction is more effective in UEL than in LEL.

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.

The Vicious Circle of Stasis, Inflammation, and Fibrosis in Lymphedema

SUMMARY

Lymphedema is a progressive disease of the lymphatic system arising from impaired lymphatic drainage, accumulation of interstitial fluid, and fibroadipose deposition. Secondary lymphedema resulting from cancer treatment is the most common form of the disease in developed countries, affecting 15% to 40% of patients with breast cancer after lymph node dissection. Despite recent advances in microsurgery, outcomes remain variable and, in some cases, inadequate. Thus, development of novel treatment strategies is an important goal. Research over the past decade suggests that lymphatic injury initiates a chronic inflammatory response that regulates the pathophysiology of lymphedema. T-cell inflammation plays a key role in this response. In this review, the authors highlight the cellular and molecular mechanisms of lymphedema and discuss promising preclinical therapies.

Gluteal lymphoedema associated with lower extremity lymphoedema: A preliminary study with indocyanine green lymphography and magnetic resonance imaging

INTRODUCTION

Indocyanine green (ICG) lymphography studies have identified that one in three to five patients with cancer-related lower extremity lymphoedema (LEL) demonstrated dermal backflow extending to the gluteal region. This study aimed to further characterize gluteal lymphoedema using contemporaneous magnetic resonance imaging (MRI).

PATIENTS AND METHODS

Twenty-eight patients with unilateral advanced LEL who underwent both ICG lymphography and MRI prior to any surgical procedure were included in this study. The patients were divided into two groups with/without gluteal lymphoedema by the presence of dermal backflow on ICG lymphography. MRI was used to evaluate tissue changes.

RESULTS

Ten patients demonstrated gluteal lymphoedema on ICG lymphography and had a higher incidence of skin hypertrophy in the gluteal region. However, no difference in excess leg volume was found between the two groups. A trend of increasing gluteal subcutaneous tissue in the affected side was identified in patients with gluteal lymphoedema with a median increase of 20% compared with an 11% increase in the non-gluteal lymphoedema group. The excess gluteal subcutaneous tissue was positively correlated to ipsilateral excess leg volume.

CONCLUSION

The gluteal lymphoedema group on ICG lymphography had skin thickening in the gluteal region and was likely identified in the secondary cancer-related group. Surgical and conservative management options for gluteal lymphoedema need to be considered in advanced LEL.

Role of Subcutaneous Adipose Tissues in the Pathophysiology of Secondary Lymphedema

Background: Secondary lymphedema (LE) occurs due to the disruption of lymphatic circulation. Lymphatic fluid accumulation in subcutaneous tissues induces adipocyte proliferation. Obesity is an important risk factor for the occurrence and deterioration of LE. Although the relationship between LE and subcutaneous adipose tissue increase has been reported clinically, their pathophysiological relationship remains unknown. Thus, we aimed to verify whether subcutaneous adipose tissue increase is involved in the pathophysiology of secondary LE. Methods and Results: The hindlimb model of secondary LE was created using male Sprague-Dawley rats (control and LE groups; n = 5 each). Skin samples were obtained on postoperative day 168. Histological examination and quantitative real-time polymerase chain reaction analysis of inflammatory adipokines, tumor necrosis factor-alpha (Tnf-α), C-C chemokine ligand 2 (Ccl2), and interleukin-6 (Il-6) were performed. Limb volume and subcutaneous adipose tissues significantly increased in the LE group compared with those in the control. Macrophages aggregated in the augmented adipose tissues, around the adipocytes, and formed crown-like structures (CLSs). The number of CLSs significantly increased in the LE group. These macrophages expressed transforming growth factor-beta 1 (TGF-β1). Inflammatory adipokine secretion was not observed. Although Il-6 expression increased in the LE group, IL-6 was expressed in subcutaneous myofibroblasts but not in subcutaneous adipocytes. Conclusion: As TGF-β1 derived from subcutaneous myofibroblasts is involved in skin fibrosis during LE, TGF-β1 derived from adipose tissues may also play a similar role. Drug treatment for subcutaneous adipose tissue reduction may improve the skin condition in secondary LE and may be a new therapeutic strategy.

Is Lymphedema a Systemic Disease? A Paired Molecular and Histological Analysis of the Affected and Unaffected Tissue in Lymphedema Patients

Secondary lymphedema is a chronic, debilitating disease and one of the most common side effects of oncologic surgery, substantially decreasing quality of life. Despite the progress conducted in lymphedema research, the underlying pathomechanisms remain elusive. Lymphedema is considered to be a disease affecting an isolated extremity, yet imaging studies suggest systemic changes of the lymphatic system in the affected patients. To evaluate potential systemic manifestations in lymphedema, we collected matched fat and skin tissue from the edematous and non-edematous side of the same 10 lymphedema patients as well as anatomically matched probes from control patients to evaluate whether known lymphedema manifestations are present systemically and in comparison to health controls. The lymphedematous tissue displayed various known hallmarks of lymphedema compared to the healthy controls, such as increased epidermis thickness, collagen deposition in the periadipocyte space and the distinct infiltration of CD4+ cells. Furthermore, morphological changes in the lymphatic vasculature between the affected and unaffected limb in the same lymphedema patient were visible. Surprisingly, an increased collagen deposition as well as CD4 expression were also detectable in the non-lymphedematous tissue of lymphedema patients, suggesting that lymphedema may trigger systemic changes beyond the affected extremity.

Acquired lymphedema: Molecular contributors and future directions for developing intervention strategies

Lymphedema is a debilitating chronic disease that mostly develops as an adverse reaction to cancer treatment modalities such as chemotherapy, surgery, and radiotherapy. Lymphedema also appears to be a deteriorating consequence of roundworm infections, as best represented by filariasis. According to its origin, lymphedema is classified as primary lymphedema and acquired lymphedema. The latter is an acquired condition that, hitherto, received a considerably low attention owing to the less number of fatal cases been reported. Notably, despite the low mortality rate in lymphedema, it has been widely reported to reduce the disease-free survival and thus the quality of life of affected patients. Hence, in this review, we focused on acquired lymphedema and orchestration of molecular interplays associated with either stimulation or inhibition of lymphedema development that were, in vast majority, clearly depicted in animal models with their specific and distinct technical approaches. We also discussed some recent progress made in phytochemical-based anti-lymphedema intervention strategies and the specific mechanisms underlying their anti-lymphedema properties. This review is crucial to understand not only the comprehensive aspects of the disease but also the future directions of the intervention strategies that can address the quality of life of affected patients rather than alleviating apparent symptoms only.

Recurrent Cellulitis: Who is at Risk and How Effective is Antibiotic Prophylaxis?

Recurrent cellulitis following successful treatment is common and prevention should be a major component in the management of cellulitis. Conditions that increase the risk of recurrence include chronic edema, venous disease, dermatomycosis and obesity. These risk factors should be actively managed as further episodes of cellulitis increases the risk of recurrence. The role of non-antibiotic measures is important and should be first-line in prevention. Antibiotic prophylaxis is effective, but its role is limited to non-purulent cellulitis where risk factors are appropriately managed.

Enhancing lymphangiogenesis and lymphatic drainage to vascularized lymph nodes with nanofibrillar collagen scaffolds

BACKGROUND

This study investigated the effect of nanofibrillar collagen scaffold (BioBridge) implantation from the affected limb to the unaffected contralateral femoral vein or lymph node in a rat model.

METHODS

Hind limb lymphedema in Lewis rats was created with lymphadenectomy and inguinal circumcision without radiation. The volumetric difference (greater than 5%) using computed tomography and indocyanine green fluorescence evaluated the progress of lymphedema at 4 weeks. The lymphedema rats have separated into Group I: Controls; Group II: implanted BioBridge to the contralateral femoral vein; and Group III: implanted BioBridge to the contralateral inguinal lymph node.

RESULTS

A total of 14 of 30 (46.7%) rats developed hind limb lymphedema with a mean volume difference of 5.83 ± 0.99% and showed diffuse dermal backflow at 4 weeks postlymphadenectomy. Four weeks postimplantation of BioBridge, the mean volumetric difference was 5.62 ± 2.11%, 4.97 ± 0.59%, and -2.47 ± 2.37% in Group I, II, and III, respectively (p < 0.05). The dermal backflow on the affected limb increased in Groups I and II but decreased in Group III.

CONCLUSIONS

Implantation of BioBridge from the affected limb to the contralateral inguinal lymph node significantly reduced the hind limb lymphedema at 4 weeks.

Updates on Excisional Procedures for Lymphedema

Significance: Excisional procedures for lymphedema have been used for over a century, and many surgeons have abandoned the old techniques as improvements in nonsurgical management and microsurgery have limited their clinical utility. Nonetheless, excisional procedures remain relevant as an important tool in the comprehensive surgical management of lymphedema. Recent Advances: Modifications to the Charles procedure and other direct excisional procedures have improved the complication profile and patient outcomes. Moreover, the use of liposuction techniques for minimally invasive tissue excision has expanded the scope of excisional surgery to benefit patients with less severe lymphedema. Recent operations combining excisional and physiologic procedures may prove to have superior results to stand-alone procedures. Critical Issues: No standard protocol exists for the comprehensive surgical management of lymphedema. Proper patient selection for any procedure requires robust outpatient assessment, cooperation with physiotherapy treatment teams, careful patient stratification, and a clear understanding of the procedure's goal. Future Directions: Larger, prospective trials will be needed to elucidate the ideal timing and combinations of techniques to optimize outcomes for patients with late-stage lymphedema.

Use of Dual-Energy X-Ray Absorptiometry to Assess Soft Tissue Composition in Breast Cancer Survivors With and Without Lymphedema

Background: In patients with lymphedema (LE), in addition to hand dominance, between-group comparisons of interlimb soft tissue differences need to account for differences in whole-body adiposity, measured directly by dual energy X-ray absorptiometry (DXA) or indirectly by body mass index. No study has evaluated the effects of hand dominance and whole-body adiposity on limb composition in patients with LE. This study's purpose was to compare soft tissue composition of affected and unaffected limbs of women with breast cancer, who did and did not have LE, controlling for dominance and percent body fat. Methods and Results: Whole-body DXA scans were acquired and included measures of percent body fat, upper limb total mass, upper limb fat mass, and upper limb fat-free mass. Participants were classified into one of three groups: women without LE; women with only subjective LE; and women with objective signs of LE at the time of assessment. Differences among the LE groups were evaluated using analysis of variance (ANOVA) and Chi-square analyses. Analysis of covariance (ANCOVA) was used to control for percent body fat and for the affected limb dominance. Compared to women without LE, women with objective signs of LE have greater total limb mass, fat mass, and fat-free mass in their affected limbs, independent of affected side dominance and percent body fat. In addition, the interlimb differences in total mass, fat mass, and fat-free mass were greater for the women with objective signs of LE, compared to the other two groups. Conclusions: DXA is useful in identifying soft tissue changes in patients with LE. Given that limb circumferences measure only changes in limb volume and that bioimpedance provides estimates of extracellular fluid, DXA has the advantage of being able to estimate the volumes of specific tissues in the limb.

Current Advancements in Animal Models of Postsurgical Lymphedema: A Systematic Review

Significance: Secondary lymphedema is a debilitating disease caused by lymphatic dysfunction characterized by chronic swelling, dysregulated inflammation, disfigurement, and compromised wound healing. Since there is no effective cure, animal model systems that support basic science research into the mechanisms of secondary lymphedema are critical to advancing the field. Recent Advances: Over the last decade, lymphatic research has led to the improvement of existing animal lymphedema models and the establishment of new models. Although an ideal model does not exist, it is important to consider the strengths and limitations of currently available options. In a systematic review adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we present recent developments in the field of animal lymphedema models and provide a concise comparison of ease, cost, reliability, and clinical translatability. Critical Issues: The incidence of secondary lymphedema is increasing, and there is no gold standard of treatment or cure for secondary lymphedema. Future Directions: As we iterate and create animal models that more closely characterize human lymphedema, we can achieve a deeper understanding of the pathophysiology and potentially develop effective therapeutics for patients.

Current Understanding of Pathological Mechanisms of Lymphedema

Significance: Lymphedema is a common disease that affects hundreds of millions of people worldwide with significant financial and social burdens. Despite increasing prevalence and associated morbidities, the mainstay treatment of lymphedema is largely palliative without an effective cure due to incomplete understanding of the disease. Recent Advances: Recent studies have described key histological and pathological processes that contribute to the progression of lymphedema, including lymphatic stasis, inflammation, adipose tissue deposition, and fibrosis. This review aims to highlight cellular and molecular mechanisms involved in each of these pathological processes. Critical Issues: Despite recent advances in the understanding of the pathophysiology of lymphedema, cellular and molecular mechanisms underlying the disease remains elusive due to its complex nature. Future Directions: Additional research is needed to gain a better insight into the cellular and molecular mechanisms underlying the pathophysiology of lymphedema, which will guide the development of therapeutic strategies that target specific pathology of the disease.

Single-cell RNA sequencing of subcutaneous adipose tissues identifies therapeutic targets for cancer-associated lymphedema

Cancer-associated lymphedema frequently occurs following lymph node resection for cancer treatment. However, we still lack effective targeted medical therapies for the treatment or prevention of this complication. An in-depth elucidation of the cellular alterations in subcutaneous adipose tissues of lymphedema is essential for medical development. We performed single-cell RNA sequencing of 70,209 cells of the stromal vascular fraction of adipose tissues from lymphedema patients and healthy donors. Four subpopulations of adipose-derived stromal cells (ASCs) were identified. Among them, the PRG4⁺/CLEC3B⁺ ASC subpopulation c3 was significantly expanded in lymphedema and related to adipose tissue fibrosis. Knockdown of CLEC3B in vitro could significantly attenuate the fibrogenesis of ASCs from patients. Adipose tissues of lymphedema displayed a striking depletion of LYVE⁺ anti-inflammatory macrophages and exhibited a pro-inflammatory microenvironment. Pharmacological blockage of Trem1, an immune receptor predominantly expressed by the pro-inflammatory macrophages, using murine LR12, a dodecapeptide, could significantly alleviate lymphedema in a mouse tail model. Cell–cell communication analysis uncovered a perivascular ligand-receptor interaction module among ASCs, macrophages, and vascular endothelial cells. We provided a comprehensive analysis of the lineage–specific changes in the adipose tissues from lymphedema patients at a single-cell resolution. CLEC3B was found to be a potential target for alleviating adipose tissue fibrosis. Pharmacological blockage of TREM1 using LR12 could serve as a promising medical therapy for treating lymphedema.

Liposuction and Controlled Compression Therapy Reduce the Erysipelas Incidence in Primary and Secondary Lymphedema

BACKGROUND

Skin infections are a recurring problem for people with lymphedema, and lymphedema has been proven to be the single most important risk factor for developing erysipelas in the leg. This study aimed to determine whether liposuction for late-stage lymphedema reduces the rate of erysipelas in lower extremity lymphedema.

METHODS

One-hundred twenty-four patients with a median age of 49 years who had liposuction and controlled compression therapy for lower extremity lymphedema were included. Excess volumes were calculated before and after surgery. Median preoperative and postoperative patient years at risk were 11 and 5 years, respectively.

RESULTS

With a total of 1680 preoperative person years at risk and 335 bouts of erysipelas experienced in 64 patients, the preoperative incidence rate was 0.20 bouts per person per year, and the period prevalence was 52%. Postoperatively, the patients were followed over a total of 763 person years at risk, and 28 patients experienced a total of 53 bouts of erysipelas, resulting in a postoperative incidence rate of 0.07 bouts per person per year, and a period prevalence of 23%. This represents a 65% decrease in the erysipelas incidence rate (P < 0.001). The preoperative median excess volume of 3158 ml was reduced with a median of 100% (P < 0.0001).

CONCLUSIONS

Liposuction and controlled compression therapy significantly reduce the risk for erysipelas in lower extremity lymphedema and completely reduces the excess volume. This finding is similar to our previous research including patients with upper extremity lymphedema.

Home-Based Intermittent Pneumatic Compression Therapy: The Impact in Chronic Leg Lymphedema in Patients Treated for Gynecologic Cancer

We conducted a prospective study of cancer patients to investigate the efficacy, quality of life, satisfaction, and safety of a home-based intermittent pneumatic compression (IPC) device during the maintenance phase of lower extremity lymphedema. This device has a unique mode designed to mimic the manual lymphatic drainage (MLD) technique and thereby gently facilitate lymphatic draining of proximal extremities. Thirty patients with stage 3 chronic secondary unilateral leg lymphedema in the maintenance phase underwent IPC and conventional compression therapy for 4 weeks at home. The participants were guided to use 1 h course (30 min of MLD-mimicking mode and 30 min of conventional mode) of IPC device twice a day for 4 weeks. We assessed the patients’ limb-volume measurement, quality of life (QOL), and satisfaction four times. There were no significant time-dependent interactions in the inter-limb volume difference ratio (Vratio). In a subgroup analysis, participants who used the home-based IPC device and maintained their routine self-maintenance program of short-stretch bandages (group B, n = 21) showed a more significant decline in Vratio than those who did not maintained their routine care (group A, n = 9). All scores of QOL decreased significantly after the intervention without subgroup difference. All participants were satisfied with the 4-week intervention. This study demonstrated that a home-based IPC device with an MLD-mimicking program is a useful option for maintaining the volume of limbs and improving the QOL of patients with stage 3 chronic leg lymphedema during the maintenance phase.

Computed Tomography-Based Quantitative Analysis of Fibrotic Changes in Skin and Subcutaneous Tissue in Lower Extremity Lymphedema Following Gynecologic Cancer Surgery

Background: Lymphedema produces protein-rich fluids that aggravate inflammation in the skin and subcutaneous tissue. Inflammation then induces fibroadipose tissue deposition and fibrosis. However, few methods have been developed to evaluate the severity of fibrosis. Therefore, we aimed to evaluate the subcutaneous fibrotic changes in lower extremity lymphedema following gynecologic cancer surgery using an image analysis tool, the FIJI software. Methods and Results: Seventy-four patients with lymphedema following gynecologic surgery were enrolled in this study. We quantitatively analyzed the cross-sectional area (CSA) of soft tissue compartments, including subcutaneous tissue with the skin, muscle volume, fibrotic changes in subcutaneous tissue, and the perimeter of skin boundaries. The limb circumference and the CSA of the subcutaneous tissue and skin on the affected side were significantly larger than those on the unaffected side. Fibrotic changes showed the same trend. However, muscle volume patterns were different from those of the other compartments. Some patients showed lower muscle volume on the unaffected side than on the affected side. Circumference and cellulitis significantly affected the extent of fibrotic changes in the skin and subcutaneous tissues. Age and duration of lymphedema did not affect fibrosis. Conclusion: Fibrosis of subcutaneous regions with the skin can be quantitatively calculated using an image analysis tool in lower extremity lymphedema following gynecologic cancer surgery. Edema and cellulitis increase fibrotic changes in the subcutaneous tissue with the skin.

Crosstalk Between Adipose and Lymphatics in Health and Disease

Adipose tissue, once thought to be an inert receptacle for energy storage, is now recognized as a complex tissue with multiple resident cell populations that actively collaborate in response to diverse local and systemic metabolic, thermal, and inflammatory signals. A key participant in adipose tissue homeostasis that has only recently captured broad scientific attention is the lymphatic vasculature. The lymphatic system's role in lipid trafficking and mediating inflammation makes it a natural partner in regulating adipose tissue, and evidence supporting a bidirectional relationship between lymphatics and adipose tissue has accumulated in recent years. Obesity is now understood to impair lymphatic function, whereas altered lymphatic function results in aberrant adipose tissue deposition, though the molecular mechanisms governing these phenomena have yet to be fully elucidated. We will review our current understanding of the relationship between adipose tissue and the lymphatic system here, focusing on known mechanisms of lymphatic-adipose crosstalk.

Effect of Postoperative Compression Therapy on the Success of Liposuction in Patients with Advanced Lower Limb Lymphedema

Objective: There is limited information on postoperative care after liposuction for lymphedema limb. The aim of this retrospective study was to identify the threshold compression pressure and other factors that lead liposuction for lower limb lymphedema to success. Materials and Methods: Patients were divided according to whether they underwent compression therapy with both stockings and bandaging (SB group), stockings alone (S group), or bandaging alone (B group) for 6 months after liposuction. The postoperative compression pressure and rate of improvement were compared according to the postoperative compression method. We also investigated whether it was possible to decrease the compression pressure after 6 months. Liposuction was considered successful if improvement rate was >15. Results: Mean compression pressure was significantly lower in the S group than in the SB group or B group. The liposuction success rate was significantly higher in the SB group than in the B group or S group. There was not a significant difference between the values at 6 months after liposuction and at 6 months after a decrease in compression pressure in the successful group. Conclusion: Our results suggest that stable high-pressure postoperative compression therapy is key to the success of liposuction for lower limb lymphedema and is best achieved by using both stockings and bandages. The postoperative compression pressure required for liposuction to be successful was >40 mmHg on the lower leg and >20 mmHg on the thigh. These pressures could be decreased after 6 months.

Crosstalk Between microRNAs and the Pathological Features of Secondary Lymphedema

Secondary lymphedema is characterized by lymphatic fluid retention and subsequent tissue swelling in one or both limbs that can lead to decreased quality of life. It often arises after loss, obstruction, or blockage of lymphatic vessels due to multifactorial modalities, such as lymphatic insults after surgery, immune system dysfunction, deposition of fat that compresses the lymphatic capillaries, fibrosis, and inflammation. Although secondary lymphedema is often associated with breast cancer, the condition can occur in patients with any type of cancer that requires lymphadenectomy such as gynecological, genitourinary, or head and neck cancers. MicroRNAs demonstrate pivotal roles in regulating gene expression in biological processes such as lymphangiogenesis, angiogenesis, modulation of the immune system, and oxidative stress. MicroRNA profiling has led to the discovery of the molecular mechanisms involved in the pathophysiology of auto-immune, inflammation-related, and metabolic diseases. Although the role of microRNAs in regulating secondary lymphedema is yet to be elucidated, the crosstalk between microRNAs and molecular factors involved in the pathological features of lymphedema, such as skin fibrosis, inflammation, immune dysregulation, and aberrant lipid metabolism have been demonstrated in several studies. MicroRNAs have the potential to serve as biomarkers for diseases and elucidation of their roles in lymphedema can provide a better understanding or new insights of the mechanisms underlying this debilitating condition.

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.

Adipocytes are larger in lymphedematous extremities than in controls

Lymphedema is caused by dysfunctional lymph vessels or as a complication of cancer treatment leading to edema and adipose tissue deposition. One hypothesis is that adipocyte hypertrophy contributes to the volume increase in lymphedema. The aim of the study was to compare adipocyte size in arm and leg lymphedema and controls. The adipocyte size difference was also compared between the arms and legs. Furthermore, any link between adipocyte size difference and gender, lymphedema onset, duration, previous radio- and chemotherapy was studied, as well as any relationship to total excess volume increase in the extremities, body mass index (BMI) and body weight. Adipose tissue biopsies from the lymphedematous and non-affected extremities were taken from 47 patients. The adipocytes sizes were measured using an Olympus PROVIS microscope, Olympus DP50 camera (Olympus, Tokyo, Japan) and ImageJ program (NIH, Bethesda, MD). Additional information was obtained from the Lymphedema Center database. The data were assembled in Excel and statistics was calculated in SPSS^® Statistics 23 (IBM^®, Armonk, NY). The adipocyte size (mean ± SEM) in the lymphedematous extremities was significantly larger, 8880 ± 291 μm², compared to the adipocyte size in the non-affected extremities, where it was 7143 ± 280 μm², i.e. 24% larger (p < .001). The adipocyte size increase was larger in arm than in leg lymphedema. No correlation was found between adipocyte size and gender or onset. However, a negative correlation was found between adipocyte size difference and duration. No correlation was found between adipocyte size and previous chemo- or radiotherapy. There was a positive correlation between adipocyte size and BMI. Hypertrophy of adipocytes was seen in the lymphedematous extremities versus control and contributes to the excess volume.

Foxo1 deletion promotes the growth of new lymphatic valves

Patients with congenital lymphedema suffer from tissue swelling in part due to mutations in genes regulating lymphatic valve development. Lymphatic valve leaflets grow and are maintained throughout life in response to oscillatory shear stress (OSS), which regulates gene transcription in lymphatic endothelial cells (LECs). Here, we identified the first transcription factor, Foxo1, that repressed lymphatic valve formation by inhibiting the expression of valve-forming genes. We showed that both embryonic and postnatal ablation of Foxo1 in LECs induced additional valve formation in postnatal and adult mice in multiple tissues. Our quantitative analyses revealed that after deletion, the total number of valves in the mesentery was significantly (P < 0.01) increased in the Foxo1LEC-KO mice compared with Foxo1fl/fl controls. In addition, our quantitative real-time PCR (RT-PCR) data from cultured LECs showed that many valve-forming genes were significantly (P < 0.01) upregulated upon knockdown of FOXO1. To confirm our findings in vivo, rescue experiments showed that Foxc2+/- mice, a model of lymphedema-distichiasis, had 50% fewer lymphatic valves and that the remaining valves exhibited backleak. Both valve number and function were completely restored to control levels upon Foxo1 deletion. These findings established FOXO1 as a clinically relevant target to stimulate de novo lymphatic valve formation and rescue defective valves in congenital lymphedema.

Advances in Lymphedema

Lymphedema is a common, complex, and inexplicably underappreciated human disease. Despite a history of relative neglect by health care providers and by governmental health care agencies, the last decade has seen an explosive growth of insights into, and approaches to, the problem of human lymphedema. The current review highlights the significant advances that have occurred in the investigative and clinical approaches to lymphedema, particularly over the last decade. This review summarizes the progress that has been attained in the realms of genetics, lymphatic imaging, and lymphatic surgery. Newer molecular insights are explored, along with their relationship to future molecular therapeutics. Growing insights into the relationships among lymphedema, obesity, and other comorbidities are important to consider in current and future responses to patients with lymphedema.

Lymphedema alters lipolytic, lipogenic, immune and angiogenic properties of adipose tissue: a hypothesis-generating study in breast cancer survivors

Later stages of secondary lymphedema are associated with the massive deposition of adipose tissue (AT). The factors driving lymphedema-associated AT (LAT) expansion in humans remain rather elusive. We hypothesized that LAT expansion could be based on alterations of metabolic, adipogenic, immune and/or angiogenic qualities of AT. AT samples were acquired from upper limbs of 11 women with unilateral breast cancer-related lymphedema and 11 healthy women without lymphedema. Additional control group of 11 female breast cancer survivors without lymphedema was used to assess systemic effects of lymphedema. AT was analysed for adipocyte size, lipolysis, angiogenesis, secretion of cytokines, immune and stem cell content and mRNA gene expression. Further, adipose precursors were isolated and tested for their proliferative and adipogenic capacity. The effect of undrained LAT- derived fluid on adipogenesis was also examined. Lymphedema did not have apparent systemic effect on metabolism and cytokine levels, but it was linked with higher lymphocyte numbers and altered levels of several miRNAs in blood. LAT showed higher basal lipolysis, (lymph)angiogenic capacity and secretion of inflammatory cytokines when compared to healthy AT. LAT contained more activated CD4+ T lymphocytes than healthy AT. mRNA levels of (lymph)angiogenic markers were deregulated in LAT and correlated with markers of lipolysis. In vitro, adipose cells derived from LAT did not differ in their proliferative, adipogenic, lipogenic and lipolytic potential from cells derived from healthy AT. Nevertheless, exposition of preadipocytes to LAT-derived fluid improved their adipogenic conversion when compared with the effect of serum. This study presents results of first complex analysis of LAT from upper limb of breast cancer survivors. Identified LAT alterations indicate a possible link between (lymph)angiogenesis and lipolysis. In addition, our in vitro results imply that AT expansion in lymphedema could be driven partially by exposition of adipose precursors to undrained LAT-derived fluid.

Liposuction of Breast Cancer-Related Arm Lymphedema Reduces Fat and Muscle Hypertrophy

Background: Adipose tissue deposition is a known consequence of lymphedema. A previous study showed that the affected arm in patients with nonpitting breast cancer-related lymphedema (BCRL) had a mean excess volume of 73% fat and 47% muscle. This condition impairs combined physiotherapy as well as more advanced microsurgical methods. Liposuction is, therefore, a way of improving the effects of treatment. This study aims to evaluate the tissue changes in lymphedematous arms after liposuction and controlled compression therapy (CCT) in patients with nonpitting BCRL.

Methods and Results: Eighteen women with an age of 61 years and a duration of arm lymphedema (BCRL) of 9 years were treated with liposuction and CCT. Tissue composition of fat, lean (muscle), and bone mineral was analyzed through dual energy X-ray absorptiometry (DXA) before, and at 3 and 12 months after surgery. Excess volumes were also measured with plethysmography. The median DXA preoperative excess volume was 1425 mL (704 mL fat volume, 651 mL lean volume). The DXA excess volume at 3 months after surgery was 193 mL (−196 mL fat volume, 362 mL lean volume). At 12 months after surgery, the median excess DXA volume was 2 mL (−269 mL fat volume, 338 mL lean volume). From before surgery to 3 months after surgery, the median DXA excess volume reduced by 85% (p < 0.001) (fat volume reduction 128% (p < 0.001), lean volume reduction 37% (p = 0.016)). From before surgery to 12 months after surgery, it reduced by 100% (p < 0.001) (fat volume reduction 139% [p < 0.001], lean volume reduction 54% [p = 0.0013]).

Conclusions: Liposuction and CCT effectively remove the excess fat in patients with nonpitting BCRL, and a total reduction of excess arm volume is achievable. A postoperative decrease in excess muscle volume is also seen, probably due to the reduced weight of the arm postoperatively.

Effects of physical therapy on hyaluronan clearance and volume regulating hormones in lower limb lymphedema patients: A pilot study

Lymphedema is manifested as a chronic swelling arising due to stasis in the lymphatic flow. No cure is currently available. A non-invasive treatment is a 3 week complete decongestive therapy (CDT), including manual lymphatic drainage and compression bandaging to control swelling. As CDT leads to mobilization of several liters of fluid, effects of CDT on hyaluronan clearance (maker for lymphatic outflow), volume regulating hormones, total plasma protein as well as plasma density, osmolality and selected electrolytes were investigated. In this pilot study, we assessed hyaluronan and volume regulating hormone responses from plasma samples of nine patients (three males, six females, aged 55 ± 13 years) with lower limb lymphedema stage II-III, before - and after - CDT. A paired non-parametric test (Wilcoxon) was used to assess hormonal and plasma volume changes. Correlation was tested using Spearman's correlation. The main findings of this novel study are that lymphedema patients lost volume and weight after therapy. Hyaluronic acid did not significantly change pre- compared to post-CDT. Aldosterone increased significantly after therapy, while plasma renin activity increased, but not significantly. Plasma total protein, density, osmolality and sodium and chloride did not show differences after CDT. To our knowledge, no study has previously investigated the effects of CDT on volume regulating hormones or electrolytes. To identify the time-course of volume regulating hormones and lymphatic flow changes induced by CDT, future studies should assess these parameters serially over 3 weeks of therapy.

Genetic Determinants of the Effects of Training on Muscle and Adipose Tissue Homeostasis in Obesity Associated with Lymphedema

It is widely accepted that metabolic changes associated with training are influenced by a person's genetic background. In this review, we explore the polymorphisms underlying interindividual variability in response to training of weight loss and muscle mass increase in obese individuals, with or without lymphedema, and in normal-weight subjects. We searched PubMed for articles in English published up to May 2019 using the following keywords: (((physical training[Title/Abstract] OR sport activity[Title/Abstract]) AND predisposition[Title/Abstract]) AND polymorphism [Title/Abstract]). We identified 38 single-nucleotide polymorphisms that may modulate the genetic adaptive response to training. The identification of genetic marker(s) that improve the beneficial effects of training may in perspective make it possible to assess training programs, which in combination with dietary intervention can optimize body weight reduction in obese subjects, with or without lymphedema. This is particularly important for patients with lymphedema because obesity can worsen the clinical status, and therefore, a personalized approach that could reduce obesity would be fundamental in the clinical management of lymphedema.

Inflammation Precedes Fat Deposition in an Experimental Model of Lymphedema

Background: Chronic lymphedema is a common complication of lymphatic obstruction, particularly after cancer treatment, characterized by an increased volume of the affected extremity, partly caused by the accumulation of excessive adipose tissue. The relationship between lymph vessels' obstruction and fat deposit is, however, poorly understood. Objective: Our central hypothesis was that the inflammatory process caused by lymph stasis precedes the adipocyte differentiation and fat deposition. Methods and Results: We used a modified mouse tail model to produce secondary lymphedema. Animals were treated with dexamethasone, or the procedure was performed in nitric oxide synthase 2 (NOS2)-deficient mice to evaluate the role of inflammation in lymphedema formation. Adipose tissue (Lipin) and inflammatory markers (IL-6, MCP-1, and F4-80) were analyzed in histological samples and by quantitative polymerase chain reaction. We observed an increased deposition of fat into the affected area that starts 3 weeks after lymph vessel ligation; it further increased after 6 weeks. Genes involved in the inflammatory process were upregulated before adipocyte maturation. Treatment with dexamethasone or the use of inducible nitric oxide synthase knockout mice blocked the inflammatory reaction and inhibited the accumulation of fat distal to the lymphatic obstruction. Conclusion: In the modified mouse tail lymphedema, inflammation precedes adipogenesis. Our data suggest that MCP-1 and nitric oxide may be potential targets for lymphedema management.

Body Mass Index and Lymphedema Morbidity: Comparison of Obese versus Normal-Weight Patients

BACKGROUND

Obesity is a risk factor for the development of secondary lymphedema after axillary lymphadenectomy and radiation therapy. The purpose of this study was to determine whether obesity influences the morbidity of lymphedema in patients who have the condition.

METHODS

Two cohorts of patients were compared: group 1, normal weight (body mass index ≤25 kg/m); and group 2, obese (body mass index ≥30 kg/m). Inclusion criteria were patients aged 21 years or older with lymphedema confirmed by lymphoscintigraphy. Covariates included age, sex, lymphedema type (primary or secondary), location, comorbidities, lymph node dissection, radiation therapy, lymphoscintigram result, and disease duration. Outcome variables were infection, hospitalization, and degree of limb overgrowth. The cohorts were compared using the Mann-Whitney U test, Fisher's exact test, and multivariable logistic regression.

RESULTS

Sixty-seven patients were included: group 1, n = 33; and group 2, n = 34. Disease duration did not differ between groups (p = 0.72). Group 2 was more likely to have an infection (59 percent), hospitalization (47 percent), and moderate or severe overgrowth (79 percent), compared to group 1 (18, 6, and 40 percent, respectively; p < 0.001). Multivariable logistic regression showed that obesity was an independent risk factor for infection (OR, 7.9; 95 percent CI, 2.5 to 26.3; p < 0.001), hospitalization (OR, 30.0; 95 percent CI, 3.6 to 150.8; p < 0.001), and moderate to severe limb overgrowth (OR, 6.7; 95 percent CI, 2.1 to 23.0; p = 0.003).

CONCLUSIONS

Obesity negatively affects patients with established lymphedema. Obese individuals are more likely to have infections, hospitalizations, and larger extremities compared to subjects with a normal body mass index. Patients with lymphedema should be counseled about the negative effects of obesity on their condition.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Potential role of transforming growth factor-beta 1/Smad signaling in secondary lymphedema after cancer surgery

Secondary lymphedema often develops after cancer surgery, and over 250 million patients suffer from this complication. A major symptom of secondary lymphedema is swelling with fibrosis, which lowers the patient's quality of life, even if cancer does not recur. Nonetheless, the pathophysiology of secondary lymphedema remains unclear, with therapeutic approaches limited to physical or surgical therapy. There is no effective pharmacological therapy for secondary lymphedema. Notably, the lack of animal models that accurately mimic human secondary lymphedema has hindered pathophysiological investigations of the disease. Here, we developed a novel rat hindlimb model of secondary lymphedema and showed that our rat model mimics human secondary lymphedema from early to late stages in terms of cell proliferation, lymphatic fluid accumulation, and skin fibrosis. Using our animal model, we investigated the disease progression and found that transforming growth factor‐beta 1 (TGFB1) was produced by macrophages in the acute phase and by fibroblasts in the chronic phase of the disease. TGFB1 promoted the transition of fibroblasts into myofibroblasts and accelerated collagen synthesis, resulting in fibrosis, which further indicates that myofibroblasts and TGFB1/Smad signaling play key roles in fibrotic diseases. Furthermore, the presence of myofibroblasts in skin samples from lymphedema patients after cancer surgery emphasizes the role of these cells in promoting fibrosis. Suppression of myofibroblast‐dependent TGFB1 production may therefore represent an effective pharmacological treatment for inhibiting skin fibrosis in human secondary lymphedema after cancer surgery.

Regulation of Lymphatic Function in Obesity

The lymphatic system has many functions, including macromolecules transport, fat absorption, regulation and modulation of adaptive immune responses, clearance of inflammatory cytokines, and cholesterol metabolism. Thus, it is evident that lymphatic function can play a key role in the regulation of a wide array of biologic phenomenon, and that physiologic changes that alter lymphatic function may have profound pathologic effects. Recent studies have shown that obesity can markedly impair lymphatic function. Obesity-induced pathologic changes in the lymphatic system result, at least in part, from the accumulation of inflammatory cells around lymphatic vessel leading to impaired lymphatic collecting vessel pumping capacity, leaky initial and collecting lymphatics, alterations in lymphatic endothelial cell (LEC) gene expression, and degradation of junctional proteins. These changes are important since impaired lymphatic function in obesity may contribute to the pathology of obesity in other organ systems in a feed-forward manner by increasing low-grade tissue inflammation and the accumulation of inflammatory cytokines. More importantly, recent studies have suggested that interventions that inhibit inflammatory responses, either pharmacologically or by lifestyle modifications such as aerobic exercise and weight loss, improve lymphatic function and metabolic parameters in obese mice. The purpose of this review is to summarize the pathologic effects of obesity on the lymphatic system, the cellular mechanisms that regulate these responses, the effects of impaired lymphatic function on metabolic syndrome in obesity, and the interventions that may improve lymphatic function in obesity.

Histopathologic Features of Lymphedema: A Molecular Review

An estimated 5 million people in the United States are affected by secondary lymphedema, with most cases attributed to malignancies or malignancy-related treatments. The pathogenesis of secondary lymphedema has historically been attributed to lymphatic injury or dysfunction; however, recent studies illustrate the complexity of lymphedema as a disease process in which many of its clinical features such as inflammation, fibrosis, adipogenesis, and recurrent infections contribute to on-going lymphatic dysfunction in a vicious cycle. Investigations into the molecular underpinning of these features further our understanding of the pathophysiology of this disease and suggests new therapeutics.

Integrating Biological Advances Into the Clinical Management of Breast Cancer Related Lymphedema

Breast cancer-related lymphedema (BCRL) occurs in a significant number of breast cancer survivors as a consequence of the axillary lymphatics' impairment after therapy (mainly axillary surgery and irradiation). Despite the recent achievements in the clinical management of these patients, BCRL is often diagnosed at its occurrence. In most cases, it remains a progressive and irreversible condition, with dramatic consequences in terms of quality of life and on sanitary costs. There are still no validated pre-surgical strategies to identify individuals that harbor an increased risk of BCRL. However, clinical, therapeutic, and tumor-specific traits are recurrent in these patients. Over the past few years, many studies have unraveled the complexity of the molecular and transcriptional events leading to the lymphatic system ontogenesis. Additionally, molecular insights are coming from the study of the germline alterations involved at variable levels in BCRL models. Regrettably, there is a substantial lack of predictive biomarkers for BCRL, given that our knowledge of its molecular milieu remains extremely puzzled. The purposes of this review were (i) to outline the biology underpinning the ontogenesis of the lymphatic system; (ii) to assess the current state of knowledge of the molecular alterations that can be involved in BCRL pathogenesis and progression; (iii) to discuss the present and short-term future perspectives in biomarker-based patients' risk stratification; and (iv) to provide practical information that can be employed to improve the quality of life of these patients.

Transcriptome analysis and functional identification of adipose-derived mesenchymal stem cells in secondary lymphedema

Background

Secondary lymphedema is a common condition that affects patients with malignant tumors. Conservative treatments fail to provide lasting relief because they do not address the underlying pathological accumulation of excessive fat. Our aim is to clarify the molecular mechanisms of abnormal adipogenic differentiation in lymphedema adipose tissue.

Methods

We compared the proliferation and adipogenesis potential of adipose-derived mesenchymal stem cells (ASCs) from the lymphedema adipose tissue from liposuction specimens of 10 patients with extremity lymphedema with that of ASCs from adipose tissue from the normal upper abdomen of the same patients. Transcriptome analysis were performed to identify the differences between the two kinds of ASCs. Cyclin-dependent kinase 1 (CDK1) inhibitors were used to treat the abnormal ASCs in lymphedema adipose tissue.

Results

Our results demonstrate that significant functional and transcriptomic differences exist between the two kinds of ASCs. Up-regulated genes were mainly involved in cell proliferation and division while down-regulated genes were mainly associated with immune responses and inflammatory as well as osteogenic and myogenic differentiation. Furthermore, we find that the excessive proliferation and adipogenesis of ASCs from lymphedema adipose tissue returned to the normal phenotype by CDK1 inhibitors. ASCs from lymphedema adipose tissues have higher immunosuppressive effect and the cytokines related to immunosuppressive was significantly up-regulated.

Conclusions

In conclusion, lymphedema-associated ASCs had more rapid proliferation and a higher adipogenic differentiation capacity. CDK1 may be a key driver of proliferation and adipogenic differentiation in these cells, which might expound the accumulation of adipose tissue extensively observed in secondary lymphedema. ASCs from lymphedema adipose tissues showed immunomodulation dysfunction and immunomodulation may play an important role in the pathogenesis of lymphedema.

The Unresolved Pathophysiology of Lymphedema

Lymphedema is the clinical manifestation of impaired lymphatic transport. It remains an under-recognized and under-documented clinical condition that still lacks a cure. Despite the substantial advances in the understanding of lymphatic vessel biology and function in the past two decades, there are still unsolved questions regarding the pathophysiology of lymphedema, especially in humans. As a consequence of impaired lymphatic drainage, proteins and lipids accumulate in the interstitial space, causing the regional tissue to undergo extensive and progressive architectural changes, including adipose tissue deposition and fibrosis. These changes are also associated with inflammation. However, the temporal sequence of these events, the relationship between these events, and their interplay during the progression are not clearly understood. Here, we review our current knowledge on the pathophysiology of lymphedema derived from human and animal studies. We also discuss the possible cellular and molecular mechanisms involved in adipose tissue and collagen accumulation during lymphedema. We suggest that more studies should be dedicated to enhancing our understanding of the human pathophysiology of lymphedema to pave the way for new diagnostic and therapeutic avenues for this condition.

Lymphedema Signs, Symptoms, and Diagnosis in Women Who Are in Minority and Low-Income Groups and Have Survived Breast Cancer

BACKGROUND

Breast cancer-related lymphedema (BCRL) is a well-known side effect of cancer and its treatment with wide-ranging prevalence estimates.

OBJECTIVE

This study describes associations between breast cancer-related lymphedema (BCRL) signs, symptoms, and diagnosis for women who were African American, white, or had a low income and survived breast cancer.

DESIGN

This is a cross-sectional, observational study that used a computer-assisted telephone interview.

METHODS

Women who had survived breast cancer were queried on the presence of 5 lymphedema signs and symptoms (edema in the breast, axilla, arm, and/or hand; tissue fibrosis; pitting; hemosiderin staining; heaviness) and whether they had a diagnosis of BCRL. Relationships between signs/symptoms and diagnosis for each group were evaluated with kappa and chi-square statistics.

RESULTS

The study sample included 528 women who had survived breast cancer (266 white and 262 African American), with 514 reporting complete data on household income; 45% of the latter reported an annual household income of ≤$20,000. Women who were African American or had a low income were nearly twice as likely as women who were white to have any of 8 signs/symptoms of BCRL. Regardless of race and income, >50% of women with all BCRL signs and symptoms reported that they were not diagnosed with BCRL.

LIMITATIONS

The main limitations of our study are the lack of medical chart data and longitudinal design.

CONCLUSIONS

Women who were African American or had a low income and had survived breast cancer had a greater burden of BCRL signs and symptoms than women who were white. The lack of a strong association between BCRL signs, symptoms, and diagnosis suggests that BCRL may be underdiagnosed. These findings suggest that more rigorous screening and detection of BCRL-especially for women who are African American or have a low income-may be warranted. Cancer rehabilitation programs may be able to fill this gap.

Quality of Life Improvements in Patients with Lymphedema After Surgical or Nonsurgical Interventions with 1-Year Follow-Up

Background: Lymphedema may impact patients' health-related quality of life (HRQoL). The purpose of this study was to evaluate HRQoL after two different treatments to the 12-month follow-up point. Methods and Results: Study participants were patients with moderate lymphedema in the upper or lower limb who attended a Swedish rehabilitation program (RP) undergoing conservative treatment, or those with severe, chronic lymphedema dominated by excess adipose tissue, who underwent liposuction (LS) combined with controlled compression therapy (CCT) in Australia, Scotland, or Sweden. The patients completed the Lymphedema Quality of Life Inventory (LyQLI) before intervention and after 1, 3, 6, and 12 months. Mean values and standard deviations were calculated for total limb volume and excess limb volume. Mean values were also calculated for the three LyQLI domains (physical, psychosocial, and practical). To detect and analyze differences in LyQLI responses in the three domains, the Wilcoxon signed rank test was performed. In the RP, 18 eligible patients completed the LyQLI. The results show improvements in HRQoL in physical (p = 0.003) and psychosocial domains (p = 0.002) at 1 month after the RP, with results remaining steady for 12 months for the physical domain (p = 0.024). Fifty-seven eligible LS patients completed the LyQLI. The results show improvements in HRQoL in all three domains (p < 0.001), with results remaining steady up to the 12-month follow-up (p < 0.001). The total volume in affected limb and the excess volume decreased significantly in both patient groups 1 month after intervention (p < 0.001). Conclusions: Treatment with a conservative RP in moderate lymphedema or with LS combined with CCT in severe lymphedema improves HRQoL.

Lymphatic vessels in human adipose tissue

Despite being considered present in most vascularised tissues, lymphatic vessels have not been properly shown in human adipose tissue (AT). Our goal in this study is to investigate an unanswered question in AT biology, regarding lymphatic network presence in tissue parenchyma. Using human subcutaneous (S-) and visceral (V-) AT samples with whole mount staining for lymphatic specific markers and three-dimensional imaging, we showed lymphatic capillaries and larger lymphatic vessels in the human VAT. Conversely, in the human SAT, microcirculatory lymphatic vascular structures were rarely detected and no initial lymphatics were found.