Lymphedema

Structure and function of vascular endothelial growth factor and its receptor system

Vascular endothelial growth factor and its receptor (VEGF-VEGFR) system play a critical role in the regulation of angiogenesis and lymphangiogenesis in vertebrates. Each of the VEGF has specific receptors, which it activates by binding to the extracellular domain of the receptors, and, thus, regulates the angiogenic balance in the early embryonic and adult stages. However, de-regulation of the VEGF-VEGFR implicates directly in various diseases, particularly cancer. Moreover, tumor growth needs a dedicated blood supply to provide oxygen and other essential nutrients. Tumor metastasis requires blood vessels to carry tumors to distant sites, where they can implant and begin the growth of secondary tumors. Thus, investigation of signaling systems related to the human disease, such as VEGF-VEGFR, will facilitate the development of treatments for such illnesses. [BMB Reports 2018; 51(2): 73-78].

Physiological Perspective on Therapies of Lymphatic Vessels

Significance: Growth of distinctive blood vessels of granulation tissue is a central step in the post-developmental tissue remodeling. Even though lymphangiogenesis is a part of the regeneration process, the significance of the controlled restoration of lymphatic vessels has only recently been recognized.

Recent Advances: Identification of lymphatic markers and growth factors paved the way for the exploration of the roles of lymphatic vessels in health and disease. Emerging pro-lymphangiogenic therapies use vascular endothelial growth factor (VEGF)-C to combat fluid retention disorders such as lymphedema and to enhance the local healing process.

Critical Issues: The relevance of recently identified lymphatic functions awaits verification by their association with pathologic conditions. Further, despite a century of research, the complete etiology of secondary lymphedema, a fluid retention disorder directly linked to the lymphatic function, is not understood. Finally, the specificity of pro-lymphangiogenic therapy depends on VEGF-C transfection efficiency, dose exposure, and the age of the subject, factors that are difficult to standardize in a heterogeneous human population.

Future Directions: Further research should reveal the role of lymphatic circulation in internal organs and connect its impairment with human diseases. Pro-lymphangiogenic therapies that aim at the acceleration of tissue healing should focus on the controlled administration of VEGF-C to increase their capillary specificity, whereas regeneration of collecting vessels might benefit from balanced maturation and differentiation of pre-existing lymphatics. Unique features of pre-nodal lymphatics, fault tolerance and functional hyperplasia of capillaries, may find applications outreaching traditional pro-lymphangiogenic therapies, such as immunomodulation or enhancement of subcutaneous grafting.

The pro-inflammatory cytokine TNF-α inhibits lymphatic pumping via activation of the NF-κB-iNOS signaling pathway

OBJECTIVE

Mesenteric lymphatic vessel pumping, important to propel lymph and immune cells from the intestinal interstitium to the mesenteric lymph nodes, is compromised during intestinal inflammation. The objective of this study was to test the hypothesis that the pro-inflammatory cytokine TNF-α, is a significant contributor to the inflammation-induced lymphatic contractile dysfunction, and to determine its mode of action.

METHODS

Contractile parameters were obtained from isolated rat mesenteric lymphatic vessels mounted on a pressure myograph after 24-hours incubation with or without TNF-α. Various inhibitors were administered, and quantitative real-time PCR, Western blotting, and immunofluorescence confocal imaging were applied to characterize the mechanisms involved in TNF-α actions.

RESULTS

Vessel contraction frequency was significantly decreased after TNF-α treatment and could be restored by selective inhibition of NF-кB, iNOS, guanylate cyclase, and ATP-sensitive K⁺ channels. We further demonstrated that NF-кB inhibition also suppressed the significant increase in iNOS mRNA observed in TNF-α-treated lymphatic vessels and that TNF-α treatment favored the nuclear translocation of the p65 NF-κB subunit.

CONCLUSIONS

These findings suggest that TNF-α decreases mesenteric lymphatic contractility by activating the NF-κB-iNOS signaling pathway. This mechanism could contribute to the alteration of lymphatic pumping reported in intestinal inflammation.

Clinical effectiveness of decongestive treatments on excess arm volume and patient-centered outcomes in women with early breast cancer-related arm lymphedema: a systematic review

OBJECTIVE

To identify the effect of decongestive lymphedema treatment on excess arm volume or patient-centered outcomes in women presenting within either 12 months or a mean nine months of developing arm lymphedema following breast cancer treatment.

INTRODUCTION

Lymphedema is a common consequence of breast cancer treatment requiring life-long treatment to reduce symptoms and prevent complications. Currently, evidence to inform the optimal decongestive lymphedema treatment package is lacking.

INCLUSION CRITERIA

The review included studies on women who received lymphedema treatment within either 12 months or a mean of nine months of developing unilateral breast cancer-related arm lymphedema. The intervention was any decongestive lymphedema treatment delivered with the purpose of reducing arm lymphedema, compared to another form of lymphedema treatment (whether self or practitioner-administered), placebo or no treatment. The clinical outcome was excess arm volume; patient-centered outcomes were health-related quality of life, arm heaviness, arm function, patient-perceived benefit and satisfaction with treatment. Experimental study designs were eligible, including randomized and non-randomized controlled trials, quasi-experimental, prospective and retrospective before and after studies were considered.

METHODS

A three-step search strategy was utilized to find published and unpublished studies. The search identified studies published from the inception of each database to July 6, 2016. Reference lists were scanned to identify further eligible studies. Studies were critically appraised using appropriate standardized critical appraisal instruments from the Joanna Briggs Institute. Details describing each study and treatment results regarding outcomes of interest were extracted from papers included in the review using appropriate standardized data extraction tools from the Joanna Briggs Institute. Due to heterogeneity in included studies, results for similar outcome measures were not pooled in statistical meta-analysis. A narrative and tabular format was used to synthesize results from identified and included studies.

RESULTS

Seven studies reporting results for outcomes of interest were critically appraised and included in the review: five randomized controlled trials and two descriptive (uncontrolled) studies. Reported outcomes included excess arm volume (five studies), health-related quality of life (three studies), arm heaviness (one study), arm function (two studies) and patient-perceived benefit (two studies). There was some evidence that decongestive treatments were effective for women presenting within either 12 months or a mean of nine months of developing breast cancer-related arm lymphedema, but the wide range of data prevented comparison of treatment findings which limited our ability to answer the review questions.

CONCLUSIONS

Weak evidence (grade B) for the impact of decongestive lymphedema treatment on women with early lymphedema (i.e. less than 12 months duration of BCRL symptoms) did not allow any conclusions to be drawn about the most effective treatment to be offered when these women first present for treatment. Findings provided no justification to support change to current practice.Future primary research needs to focus on the most effective treatment for women when they first present with lymphedema symptoms, e.g. treatment provided within 12 months of developing symptoms. Studies should be adequately powered and recruit women exclusively with less than 12 months duration of breast cancer-related lymphedema symptoms, provide longer follow-up to monitor treatment effect over time, with comparable treatment protocols, outcome measures and reporting methods.

Methicillin-resistant Staphylococcus aureus causes sustained collecting lymphatic vessel dysfunction

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of morbidity and mortality worldwide and is a frequent cause of skin and soft tissue infections (SSTIs). Lymphedema-fluid accumulation in tissue caused by impaired lymphatic vessel function-is a strong risk factor for SSTIs. SSTIs also frequently recur in patients and sometimes lead to acquired lymphedema. However, the mechanism of how SSTIs can be both the consequence and the cause of lymphatic vessel dysfunction is not known. Intravital imaging in mice revealed an acute reduction in both lymphatic vessel contractility and lymph flow after localized MRSA infection. Moreover, chronic lymphatic impairment is observed long after MRSA is cleared and inflammation is resolved. Associated with decreased collecting lymphatic vessel function was the loss and disorganization of lymphatic muscle cells (LMCs), which are critical for lymphatic contraction. In vitro, incubation with MRSA-conditioned supernatant led to LMC death. Proteomic analysis identified several accessory gene regulator (agr)-controlled MRSA exotoxins that contribute to LMC death. Infection with agr mutant MRSA resulted in sustained lymphatic function compared to animals infected with wild-type MRSA. Our findings suggest that agr is a promising target to preserve lymphatic vessel function and promote immunity during SSTIs.

Lymphedema: Diagnostic workup and management

Lymphedema is a localized form of tissue swelling resulting from excessive retention of lymphatic fluid in the interstitial compartment. It is caused by impaired lymphatic drainage. Lymphedema is a chronic progressive disease with serious physical and psychosocial implications. It can be challenging to diagnose, especially in obese patients and in those with coexisting venous disease. We performed PubMed and Google Scholar searches of the English-language literature (1966-2017) using the terms lymphedema, lymphedema management, and lymphatic complications. Relevant publications were manually reviewed for additional resources. There are currently no standard guidelines for the diagnosis of lymphedema. There is no cure yet for lymphedema, and the objective for management is to limit disease progression and prevent complications.

Lymphedema: Pathophysiology and clinical manifestations

Lymphedema is a localized form of tissue swelling resulting from excessive retention of lymphatic fluid in the interstitial compartment and caused by impaired lymphatic drainage. Lymphedema is classified as primary or secondary. Primary lymphedema is caused by developmental lymphatic vascular anomalies. Secondary lymphedema is acquired and arises as a result of an underlying systemic disease, trauma, or surgery. We performed PubMed and Google Scholar searches of the English-language literature (1966-2017) using the terms lymphedema, cancer-related lymphedema, and lymphatic complications. Relevant publications were manually reviewed for additional resources. This progressive chronic disease has serious implications on patients' quality of life. It is often misdiagnosed because it mimics other conditions of extremity swelling. There is no definitive cure for lymphedema. However, with proper diagnosis and management, its progression and potential complications may be limited.

Lymphedema secondary to idiopathic occlusion of the subclavian and innominate veins after renal transplantation: A case report

RATIONALE

Among the causes of swelling in the extremities of renal transplantation patients, secondary lymphedema caused by complete idiopathic obstruction of large veins is rare and may be difficult to diagnose and treat.

PATIENT CONCERNS

A 64-year-old man presented with severe edema and pain that occurred suddenly in the right arm.

DIAGNOSES

The patient was diagnosed as stage-2 secondary lymphedema caused by idiopathic occlusion of the subclavian and innominate veins.

INTERVENTIONS

Lymphoscintigraphy and ascending venography of the right arm confirmed the diagnosis. Intensive complete decongestive therapy for lymphedema was performed.

OUTCOMES

Following 2 weeks of active rehabilitation, the pain level and edema status were significantly improved.

LESSONS

When idiopathic swelling of the extremities occurs in renal transplant patients, secondary lymphedema caused by venous occlusion may be the cause. When direct intervention for the venous occlusion proves to be difficult, a conservative approach may be helpful.

Mechanotransduction in Blood and Lymphatic Vascular Development and Disease

The blood and lymphatic vasculatures are hierarchical networks of vessels, which constantly transport fluids and, therefore, are exposed to a variety of mechanical forces. Considering the role of mechanotransduction is key for fully understanding how these vascular systems develop, function, and how vascular pathologies evolve. During embryonic development, for example, initiation of blood flow is essential for early vascular remodeling, and increased interstitial fluid pressure as well as initiation of lymph flow is needed for proper development and maturation of the lymphatic vasculature. In this review, we introduce specific mechanical forces that affect both the blood and lymphatic vasculatures, including longitudinal and circumferential stretch, as well as shear stress. In addition, we provide an overview of the role of mechanotransduction during atherosclerosis and secondary lymphedema, which both trigger tissue fibrosis.

Lymph Drainage from the Chylocyst-Induced Hemodilution in an In Vivo Rabbit Study

To confirm our previous study that abdominal respiration has induced hemodilution in human subjects, we performed in-vivo experiments involving anesthetized rabbits. Fifteen 6- to 7-month-old male Japanese white rabbits were used in the animal experiments. Anesthesia was maintained with 2.5%-3.0% isoflurane under N₂O + 100% O₂ inhalation. Ventilation was maintained at 40 mL/breath for 20 breaths/min. Physiological saline solution was administered at rated 18 mL/h during the experiments. First, we attempted to evaluate lymph flow through the thoracic duct using Sonazoid-based contrast-enhanced ultrasound (CEUS)-guided method and then investigated the effects of manual lymph drainage of the chylocyst on the numbers of red blood cells (RBC), hematocrit (Ht) levels, and the blood concentrations of total protein (TP) and hemoglobin (Hb). In this study, we established surgical methods for identifying the left venous angle and chylocyst using Evans blue dye in anesthetized rabbits. We also confirmed that a Sonazoid-based CEUS-guided method was the most useful technique for producing real-time images of lymph flow through the thoracic duct in anesthetized rabbits. In addition, in present experiments involving anesthetized rabbits, we confirmed that manually massaging the chylocyst produced significant hemodilution. Thus, the procedure produced significant reductions of TP, RBC, Hb, and Ht level in the rabbits.

Sphingosine 1-phosphate receptor 1 regulates the directional migration of lymphatic endothelial cells in response to fluid shear stress

The endothelial cells that line blood and lymphatic vessels undergo complex, collective migration and rearrangement processes during embryonic development, and are known to be exquisitely responsive to fluid flow. At present, the molecular mechanisms by which endothelial cells sense fluid flow remain incompletely understood. Here, we report that both the G-protein-coupled receptor sphingosine 1-phosphate receptor 1 (S1PR1) and its ligand sphingosine 1-phosphate (S1P) are required for collective upstream migration of human lymphatic microvascular endothelial cells in an in vitro setting. These findings are consistent with a model in which signalling via S1P and S1PR1 are integral components in the response of lymphatic endothelial cells to the stimulus provided by fluid flow.

The Lymphatic Vasculature: Its Role in Adipose Metabolism and Obesity

Obesity is a key risk factor for metabolic and cardiovascular diseases, and although we understand the mechanisms regulating weight and energy balance, the causes of some forms of obesity remain enigmatic. Despite the well-established connections between lymphatics and lipids, and the fact that intestinal lacteals play key roles in dietary fat absorption, the function of the lymphatic vasculature in adipose metabolism has only recently been recognized. It is well established that angiogenesis is tightly associated with the outgrowth of adipose tissue, as expanding adipose tissue requires increased nutrient supply from blood vessels. Results supporting a crosstalk between lymphatic vessels and adipose tissue, and linking lymphatic function with metabolic diseases, obesity, and adipose tissue, also started to accumulate in the last years. Here we review our current knowledge of the mechanisms by which defective lymphatics contribute to obesity and fat accumulation in mouse models, as well as our understanding of the lymphatic-adipose tissue relationship.

A vicious circle in chronic lymphoedema pathophysiology? An adipocentric view

Chronic lymphoedema is a disease caused by a congenital or acquired damage to the lymphatic system and characterized by complex chains of pathophysiologic events such as lymphatic fluid stasis, chronic inflammation, lymphatic vessels impairment, adipose tissue deposition and fibrosis. These events seem to maintain and reinforce themselves through a positive feedback loop: regardless of the initial cause of lymphatic stasis, the dysfunctional adipose tissue and its secretion products can worsen lymphatic vessels' function, aggravating lymph leakage and stagnation, which can promote further adipose tissue deposition and fibrosis, similar to what may happen in obesity. In addition to the current knowledge about the tight and ancestral interrelation between immunity system and metabolism, there is evidence for similarities between obesity-related and lymphatic damage-induced lymphoedema. Together, these observations indicate strong reciprocal relationship between lymphatics and adipose tissue and suggest a possible key role of the adipocyte in the pathophysiology of chronic lymphoedema's vicious circle.

Demonstration and Analysis of the Suction Effect for Pumping Lymph from Tissue Beds at Subatmospheric Pressure

Many tissues exhibit subatmospheric interstitial pressures under normal physiologic conditions. The mechanisms by which the lymphatic system extracts fluid from these tissues against the overall pressure gradient are unknown. We address this important physiologic issue by combining experimental measurements of contractile function and pressure generation with a previously validated mathematical model. We provide definitive evidence for the existence of 'suction pressure' in collecting lymphatic vessels, which manifests as a transient drop in pressure downstream of the inlet valve following contraction. This suction opens the inlet valve and is required for filling in the presence of low upstream pressure. Positive transmural pressure is required for this suction, providing the energy required to reopen the vessel. Alternatively, external vessel tethering can serve the same purpose when the transmural pressure is negative. Suction is transmitted upstream, allowing fluid to be drawn in through initial lymphatics. Because suction plays a major role in fluid entry to the lymphatics and is affected by interstitial pressure, our results introduce the phenomenon as another important factor to consider in the study of lymphoedema and its treatment.

Classification of Vascular Anomalies: An Update

Vascular anomalies present both a diagnostic and therapeutic challenge to physicians. Identification of these lesions is difficult due to their immense phenotypic variability, and naming conventions for vascular anomalies have historically been inconsistent. Terms such as "hemangioma" are informative when used correctly, but can cause confusion and miscommunication if applied indiscriminately to all vascular anomalies. Accuracy in classification is essential, as both disease course and therapeutic options differ greatly depending on the particular vascular anomaly present. In order for clinicians to properly diagnose and treat patients with these diseases, a unified nomenclature must be employed. This section provides an update on the current classification of vascular anomalies, with clinical descriptions of the most commonly encountered lesions, and clarifies the ambiguous nomenclature present in the existing literature.

Cardiac Lymphatic Vessels, Transport, and Healing of the Infarcted Heart

The lymphatic vasculature plays a key role in regulating tissue fluid homeostasis, lipid transport, and immune surveillance throughout the body. Although it has been appreciated that the heart relies on lymphatic vessels to maintain fluid balance and that such balance must be tightly maintained to allow for normal cardiac output, it has only recently come to light that the lymphatic vasculature may serve as a therapeutic target with which to promote optimal healing following myocardial ischemia and infarction. This article reviews the subject of cardiac lymphatic vessels and highlights studies that imply targeting of lymphatic vessel development or transport using vascular endothelial growth factor-C therapy may serve as a promising avenue for future clinical application in the context of ischemic injury.

RAMP1 signaling improves lymphedema and promotes lymphangiogenesis in mice

BACKGROUND

Secondary lymphedema commonly arises as a complication of cancer surgery and radiation treatment; however, the underlying mechanisms are poorly understood. Receptor activity-modifying protein 1 (RAMP1) forms a complex with calcitonin receptor-like receptor to generate the receptor for calcitonin gene-related peptide. The present study examined whether RAMP1 plays a role in increased lymphangiogenesis during secondary lymphedema.

METHODS

A model of lymphedema was generated by surgical removal of pre-existing lymphatic vessels from the subcutaneous tissue on the tails of RAMP1-deficient (RAMP1-/-) mice and their wild-type (WT) counterparts. The maximum diameter of the tail, lymphangiogenesis, and macrophage recruitment were then examined.

RESULTS

Compared with that in WT mice, lymphedema in the tails in RAMP1-/- mice was sustained, with suppressed lymphangiogenesis and reduced expression of vascular endothelial growth factor-C and vascular endothelial growth factor receptor 3 at the distal edge of the lesions. The newly formed lymphatic vessels in RAMP1-/- mice were dilated, with impaired lymphatic flow. RAMP1 was expressed by macrophages recruited into edematous tail tissues distal to the wound. The number of macrophages in RAMP1-/- mice was higher than that in WT mice. Expression of messenger RNA encoding M1 macrophage-related genes, including tumor necrosis factor-α and interleukin-1, was higher in RAMP1-/- mice than in WT mice, whereas expression of messenger RNA encoding M2 macrophage genes, including interleukin-10, was lower.

CONCLUSIONS

RAMP1 signaling improves lymphedema and accelerates lymphangiogenesis associated with reduced recruitment of pro-inflammatory macrophages.

A Galvanic Intrabody Method for Assessing Fluid Flow in Unilateral Lymphoedema

Lymphoedema is a disease associated with abnormal functioning of the lymph that leads to swelling of the body due to accumulation of tissue fluid on the affected area. Tissue fluid contains ions and electrolytes that affect electrical conductivity. The flow of tissue fluid helps to distribute vital nutrients and other important elements necessary for healthy living. When tissue fluid is stagnated, a high concentration of electrolytes accumulate on the affected area, which in turn affects an electrical signal passing through that area to be minimally attenuated in relation to a free-flowing fluid. We demonstrate that a galvanic coupled signal propagating along a lymphoedema affected limb could capture these changes by the amount of attenuation the propagating signal experiences in time. Our results show that average rate of signal attenuation on a lymphoedema affected part of the body could be as slow as 0.16 dB/min, while the rate of signal attenuation on a healthy part is as high as 1.83 dB/min. This means that fluid accumulation could slow down the exchange of body electrolytes up to twice less the rate on an unaffected contralateral part of the body. Monitoring these changes by observing the average rate of change of a galvanic coupled signal attenuation on the affected body part can be used for diagnosing early developments of oedema in the body and for evaluating recovery in response to treatment procedures.

Modified Mouse Models of Chronic Secondary Lymphedema: Tail and Hind Limb Models

BACKGROUND

Postsurgical secondary lymphedema is usually a progressive and lifelong condition lacking any curative treatment. The aim of this study was to develop new, simple surgical mouse models of chronic lymphedema, better simulating chronic nature of human postsurgical lymphedema.

METHODS

Two experimental mouse models of secondary lymphedema were created surgically without radiation by modifications of the previously described methods: the tail model and the hind limb model. Lymphedema formation was clinically assessed and quantitatively evaluated by measuring circumferences and limb volumes. Postmortem specimens were assessed histologically to examine the efficacy of the models.

RESULTS

In the tail models, although a substantial frequency of tail necrosis (30.0%) was noted and the increase in circumference was maintained for only limited times postoperatively depending on the particular tail model, the overall success rate was 65.0%. In the mouse hind limb model, the overall success rate was 88.9%, and the increased circumference and limb volume were maintained over the entire study period of 8 weeks. The overall success rate of the mouse hind limb model was significantly higher than that of the mouse tail model(s).

CONCLUSIONS

We have successfully established modified mouse tail and hind limb lymphedema models via only surgical techniques without radiation, which have characteristics of chronic secondary lymphedema. The mouse hind limb model has a higher success rate than the mouse tail model and has advantages of having the healthy contralateral hind limbs as an internal control.

High-Fat Diet in the Absence of Obesity Does Not Aggravate Surgically Induced Lymphoedema in Mice

BACKGROUND

Lymphoedema represents the cardinal manifestation of lymphatic dysfunction and is associated with expansion of the adipose tissue in the affected limb. In mice, high-fat diet (HFD)-induced obesity was associated with impaired collecting lymphatic vessel function, and adiposity aggravated surgery-induced lymphoedema in a mouse model. The aim of the current study was to investigate whether adiposity is necessary to impair lymphatic function or whether increased lipid exposure alone might be sufficient in a surgical lymphoedema model.

METHODS

To investigate the role of increased lipid exposure in lymphoedema development we used a well-established mouse tail lymphoedema model. Female mice were subjected to a short-term (6 weeks) HFD, without development of obesity, before surgical induction of lymphedema. Lymphoedema was followed over a period of 6 weeks measuring oedema, evaluating tissue histology and lymphatic vascular function.

RESULTS

HFD increased baseline angiogenesis and average lymphatic vessel size in comparison to the chow control group. Upon induction of lymphedema, HFD-treated mice did not exhibit aggravated oedema and no morphological differences were observed in the blood and lymphatic vasculature. Importantly, the levels of fibro-adipose tissue deposition were comparable between the 2 groups and lymphatic vessel function was not impaired as a result of the HFD. Although the net immune cell infiltration was comparable, the HFD group displayed an increased infiltration of macrophages, which exhibited an M2 polarization phenotype.

CONCLUSIONS

These results indicate that increased adiposity rather than dietary influences determines predisposition to or severity of lymphedema.

Therapeutic effects of hyaluronidase on acquired lymphedema using a newly developed mouse limb model

Acquired lymphedema is one of the most dreaded side effects of cancer treatment, such as surgical treatment or irradiation. However, due to the lack of appropriate animal models, there is no effective therapeutic method to cure acquired lymphedema. To develop a reproducible acquired lymphedema animal model, we devised a mouse hind limb model by removing a superficial inguinal lymph node, a popliteal lymph node, a deep inguinal lymph node, and the femoral lymphatic vessel. We measured the volume of lymphedematous leg and observed the change in level of hyaluronic acid (HA) and lymphangiogenic factors after injecting hyaluronidase. Our model showed the distinguishable swelling and the reliable symptoms compared to previously reported models. In the lymphedematous regions of our model, we confirmed that HA, a major component of extracellular matrix, accumulated to higher levels than in a normal mouse. This lymphedema volume was rapidly reduced by treating hyaluronidase. Following hyaluronidase injection, the lymphedematous region of our model resembled a normal hind limb. Our findings indicated that hyaluronidase promoted lymphangiogenesis on the lymphedematous limb. Based on hyaluronidase treatment in the lymphedematous region, this could potentially be a new therapeutic approach for acquired lymphedema mediated through the modification of the size of HA fragments. Impact statement In this manuscript, the essence of the work described in this manuscript involves the development of (1) a mouse limb model showing acquired lymphedema and (2) a potent therapeutic treatment using hyaluronidase to remedy acquired lymphedema in our model. In order to develop a reproducible acquired lymphedema animal model that reflects the most common symptoms experienced by lymphedema patients, we devised a mouse hind limb model by removing lymph nodes and lymphatics. Our model showed the distinguishable swelling and the reliable symptoms compared to previously reported models. In the lymphedematous regions of our model, we confirmed that hyaluronic acid (HA) accumulated to higher levels than in a normal mouse. This lymphedema volume was rapidly reduced by treating the lymphedematous leg with hyaluronidase, which also degraded high molecular weight HA to low molecular weight HA. Immunohistochemical analysis, quantitative real-time PCR analysis and lymphangioscintigraphy showed that hyaluronidase enhanced lymphangiogenesis in the lymphedematous limb.

Primary Upper Limb Lymphedema: Case Report of a Rare Pathology

INTRODUCTION

Lymphedema is characterized by a defect in the lymphatic system that causes limb swelling. Impaired uptake and transport of lymphatic fluid through lymphatic vessels causes accumulation of protein-rich fluid in the interstitial spaces, which leads to swelling of the limb. Primary lymphedema often presents at birth. The rare cases that arise after age 35 years are described as lymphedema tarda. The great majority of patients with lymphedema have swelling of the lower limbs-upper limb lymphedema is a rare disorder.

CASE PRESENTATION

An 84-year-old woman presented with a 3-year history of unilateral swelling of the right upper limb. There were no constitutional symptoms and no evidence of lymphadenopathy or systemic disease. Blood tests, carcinoembryonic antigen test, computed tomography scans, and venous Doppler ultrasound were all normal. The diagnosis was primary upper limb lymphedema.

DISCUSSION

The swelling that occurs in upper limb lymphedema is permanent and usually extends to the hand. About one-third of patients with this condition also present with lower limb lymphedema. Thorough investigations are warranted in cases of unilateral upper limb lymphedema to rule out occult malignancy and systemic disease.

Satisfaction with a therapeutic sleeve for arm lymphedema secondary to breast cancer treatment: Controlled crossover trial

Highlights

Secondary lymphedema is a late iatrogenic side effect of breast cancer treatment.Despite multimodal decongestive therapy in their daily life breast cancer survivors with lymphedema have few alternatives but to use a compressive sleeve.Concerned with the well-known low compliance to the daily use of traditional sleeves, we conducted a comparative study to evaluate the subjective assessment of an innovative class 1 compression sleeve.We concluded that the PRADEX^® sleeve, not being worse in its compressive efficacy, is much better with regard to patient comfort.

Abstract

Secondary arm lymphedema is a feared late iatrogenic side effect of breast cancer survivors with a negative impact on patient's self-image and quality of life. Its reported incidence is extremely variable, from 6% to 80%, as well as the effectiveness of the multimodal decongestive lymphedema therapy.In their daily life breast cancer survivors with lymphedema have few alternatives but to use a compressive sleeve. Concerned with the well-known low compliance to the daily use of traditional sleeves, we conducted a comparative study in a subgroup of our patients with lymphedema secondary to breast cancer treatment for the subjective assessment of PRADEX^®, an innovative class 1 compression sleeve. Secondarily, we aimed to assess the non-inferiority of PRADEX^® regarding subjective and objective measures of the severity of lymphedema.We studied 46 women with grade 1 secondary arm lymphedema, who used their usual sleeve and PRADEX^® daily for 2 weeks each, in a crossover design.The new therapeutic sleeve was classified as having a better design and a better usability and comfort (more comfortable, thinner, fresher, softer, more flexible, comfortable, resistant to dirt and easier to dress and to wear). Women's subjective opinion about the severity of lymphedema favored their usual sleeve in detriment of PRADEX^®, but this subjective feeling was contradicted by objective measurements of different perimeters of the arm at the beginning and at the end of the study.We concluded that the PRADEX^® sleeve, not being worse in its compressive therapeutic efficacy, is much better with regard to patient comfort.

Circumferential suction-assisted lipectomy in the treatment of primary and secondary end-stage lymphoedema of the leg

Background

The treatment of end-stage lymphoedema of the leg is challenging, especially when conservative treatment fails and there is a large volume difference between the affected and unaffected legs. Circumferential suction-assisted lipectomy (CSAL) has been described as a treatment option for end-stage lymphoedema of the leg. Here, the long-term results of CSAL in end-stage primary and secondary lymphoedema of the leg were analysed.

Methods

This was a descriptive study of patients treated with CSAL for unilateral chronic irreversible lymphoedema of the leg. Compression therapy was resumed after surgery. Leg volumes were measured before surgery, and at 1, 6, 12 and 24 months after the procedure.

Results

A total of 47 patients with primary lymphoedema had a median preoperative volume difference between affected and unaffected legs of 3686 (i.q.r. 2851–5121) ml. Two years after surgery, this volume difference was reduced to 761 ml, a 79 per cent reduction. In the 41 patients treated for secondary lymphoedema, the median preoperative volume difference was 3320 (i.q.r. 2533–4783) ml, decreasing after 2 years to −38 ml (101 per cent reduction). The preoperative volume difference and the sex of the patient significantly influenced the final outcome after 2 years. The outcome was not related to BMI or other patient characteristics.

Conclusion

CSAL is an effective method for treating both primary and secondary lymphoedema of the leg.

Diphtheria toxin-mediated ablation of lymphatic endothelial cells results in progressive lymphedema

Development of novel treatments for lymphedema has been limited by the fact that the pathophysiology of this disease is poorly understood. It remains unknown, for example, why limb swelling resulting from surgical injury resolves initially, but recurs in some cases months or years later. Finding answers for these basic questions has been hampered by the lack of adequate animal models. In the current study, we used Cre-lox mice that expressed the human diphtheria toxin receptor (DTR) driven by a lymphatic-specific promoter in order to noninvasively ablate the lymphatic system of the hind limb. Animals treated in this manner developed lymphedema that was indistinguishable from clinical lymphedema temporally, radiographically, and histologically. Using this model and clinical biopsy specimens, we show that the initial resolution of edema after injury is dependent on the formation of collateral capillary lymphatics and that this process is regulated by M2-polarized macrophages. In addition, we show that despite these initial improvements in lymphatic function, persistent accumulation of CD4⁺ cells inhibits lymphangiogenesis and promotes sclerosis of collecting lymphatics, resulting in late onset of edema and fibrosis. Our findings therefore provide strong evidence that inflammatory changes after lymphatic injury play a key role in the pathophysiology of lymphedema.

"The Monkey on Your Shoulder": A Qualitative Study of Lymphoedema Patients' Attitudes to and Experiences of Acupuncture and Moxibustion

Background. Lymphoedema, a distressing consequence of cancer treatment, has significant negative impact on health-related quality of life. Multidisciplinary approaches are needed to improve physical and psychosocial wellbeing. Acupuncture and moxibustion (acu/moxa), two modalities of traditional East Asian medicine, may contribute to improved outcomes for cancer survivors with lymphoedema. Aim. To explore how patients with lymphoedema secondary to cancer treatment perceive and experience acu/moxa treatment. Design and Setting. A qualitative focus group study, nested in a 3-step mixed methods observational study, was carried out in a cancer drop-in and information centre in north-west London. Methods. Six focus groups and one telephone interview were conducted with 23 survivors of breast or head and neck cancer, who had completed up to 13 acu/moxa treatments. Scripts were transcribed, coded, and analysed to identify salient and overarching themes. Results. Participants described feeling disempowered by cancer treatment and subsequent diagnosis of lymphoedema. Acu/moxa was valued for its whole-person approach and for time spent with a practitioner who cared, listened, and responded. Participants reported changes in physical and psychosocial health, including increased energy levels and reduced pain and discomfort, and feelings of empowerment, personal control, and acceptance. Many were motivated to improve self-care. Conclusion. Many participants who received acu/moxa treatment reported improved wellbeing and a more proactive attitude towards self-care.

Deep vein thrombosis (DVT) in advanced cancer patients with lower extremity edema referred for assessment

Lower extremity edema is a common complication in advanced cancer patients, and deep vein thrombosis (DVT) is one among many causes. Clinical signs and symptoms are known to be unreliable, and radiographic investigations are often required in diagnosing DVT. A retrospective chart review was conducted on 46 advanced cancer patients with lower extremity edema. Researchers analyzed 52 venous duplex scans to determine the radiographic incidence of DVT, the reliability of other clinical signs and symptoms in diagnosing DVT, apart from leg edema, and to assess other potential causes of lower extremity edema and their correlation to DVT. Twenty-three (44 percent) of 52 scans were positive for DVT. The most common presentation of edema in the patients with positive scans was bilateral asymmetric edema (11/23, 48 percent). There was limited documentation of other clinical signs and symptoms suggesting DVT. Other variables such as serum albumin (p = 0.46) and creatinine (p = 0.11) were not statistically different in patients who had positive and negative scans. Of other potential causes of lower extremity edema, such as previous surgery, radiotherapy, tumor, or lymph node compression, a number of patients had a coexisting DVT with bilateral asymmetric edema as the most common presentation. The results of this study suggest that advanced cancer patients with bilateral asymmetric lower extremity edema of potentially multifactorial origin have a high incidence of DVT.

Manual Lymphatic Drainage Therapy

Health care providers are constantly confronted with the challenge of providing quality health care while at the same time containing escalating costs. Incorporating complementary therapies into standard health care practices can assist in escalating the healing process, enhancing general wellness, focusing on prevention, and promoting a better quality of life. This article discusses manual lymphatic drainage therapy and identifies the value of as well the indications for the therapy. A brief overview of the lymphatic system is included.

A Review of Engineering Approaches for Lymphedema Detection

Edema is a condition characterized by excessive swelling of a tissue due to an abnormal accumulation of interstitial fluid in the subcutaneous tissue. More specifically, disruption of the lymphatic system causes what is known as lymphedema. This condition is commonly seen in breast cancer survivors postradiotherapy treatment, chemotherapy, and surgeries; this population has shown high risk of developing lymphedema in the limbs. Throughout the years, several techniques have been developed and implemented for the detection and measurement of lymphedema, including techniques to measure the diseased limb volume, electrical techniques to measure the water content in tissues, and optical techniques to measure either tissue absorbance or limb volume. However, there is still no method that allows for continuous monitoring of the disease and provides a better understanding of its progression. This study describes the different approaches that have been used and that could be used for lymphedema measurement.

Prominent Lymphatic Vessel Hyperplasia with Progressive Dysfunction and Distinct Immune Cell Infiltration in Lymphedema

Lymphedema is a common complication that occurs after breast cancer treatment in up to 30% of the patients undergoing surgical lymph node excision. It is associated with tissue swelling, fibrosis, increased risk of infection, and impaired wound healing. Despite the pronounced clinical manifestations of the disease, little is known about the morphological and functional characteristics of the lymphatic vasculature during the course of lymphedema progression. We used an experimental murine tail lymphedema model where sustained fluid stasis was generated on disruption of lymphatic flow, resulting in chronic edema formation with fibrosis and adipose tissue deposition. Morphological analysis of the lymphatic vessels revealed a dramatic expansion during the course of the disease, with active proliferation of lymphatic endothelial cells at the early stages of lymphedema. The lymphatic capillaries exhibited progressively impaired tracer filling and retrograde flow near the surgery site, whereas the collecting lymphatic vessels showed a gradually decreasing contraction amplitude with unchanged contraction frequency, leading to lymphatic contraction arrest at the later stages of the disease. Lymphedema onset was associated with pronounced infiltration by immune cells, predominantly Ly6G(+) and CD4(+) cells, which have been linked to impaired lymphatic vessel function.

Restoration of lymphatic function rescues obesity in Prox1-haploinsufficient mice

Prox1 heterozygous mice have a defective lymphatic vasculature and develop late-onset obesity. Chyle abnormally leaks from those vessels, accumulates in the surrounding tissues, and causes an increase in adipose tissue. We characterized the lymphatics of Prox1^+/- mice to determine whether the extent of obesity correlated with the severity of lymphatic defects. The lymphatic vasculature in Prox1^+/- mice exhibited reduced tracer clearance from the ear skin, dysfunctional perfusion of the lower legs, and reduced tracer uptake into the deep lymphatic collectors during mechanostimulation prior to the onset of obesity. Ear lymphatic vessels and leg collectors in Prox1^+/- mice were disorganized and irregular, further confirming that defective lymphatic vessels are associated with obesity in Prox1^+/- mice. We now provide conclusive in vivo evidence that demonstrates that leaky lymphatics mediate obesity in Prox1^+/- mice, as restoration of lymphatic vasculature function was sufficient to rescue the obesity features in Prox1^+/- mice. Finally, depth-lipomic profiling of lymph contents showed that free fatty acids induce adipogenesis in vitro.

Sotos syndrome: An unusual presentation with intrauterine growth restriction, generalized lymphedema, and intention tremor

Sotos syndrome is a childhood overgrowth syndrome characterized clinically by a distinctive facial gestalt, advanced bone age, childhood overgrowth, and non-progressive developmental delay; and genetically by haploinsufficiency of the Nuclear receptor binding SET Domain 1 (NSD1) gene. Generalized lymphedema has not previously been associated with Sotos syndrome. Generalized lymphedema has been associated with mutations in several genes including FLT4. This gene is involved in the regulation of VEGFR3, a key governor of lymphatic-endothelial cell development and function. We report on a 28-year-old Caucasian female with a de novo NSD1 intragenic mutation, c.5841_5848dup: p.Leu1950Serfs*22, who presented with characteristic clinical features of Sotos syndrome. Unusually this case includes atypical features of intrauterine growth retardation and post-pubertal onset of primary lymphedema. To our knowledge, no link between Sotos syndrome and generalized lymphedema has previously been described in the literature. We propose a mechanism by which disruptions in NSD1 gene may lead to generalized lymphedema. Aberrations of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK)-signaling pathway has been identified in both Sotos syndrome and lymphedema. This finding extends the known phenotype of Sotos syndrome through the inclusion of lymphedema. This case also indicates that presence of low birth weight does not exclude the possibility of Sotos syndrome.

Excess Lymphangiogenesis Cooperatively Induced by Macrophages and CD4(+) T Cells Drives the Pathogenesis of Lymphedema

Lymphedema is a debilitating progressive condition that severely restricts quality of life and is frequently observed after cancer surgery. The mechanism underlying lymphedema development remains poorly understood, and no effective pharmacological means to prevent or alleviate the ailment is currently available. Using a mouse model of lymphedema, we show here that excessive generation of immature lymphatic vessels is essential for initial edema development and that this early process is also important for later development of lymphedema pathology. We found that CD4(+) T cells interact with macrophages to promote lymphangiogenesis, and that both lymphangiogenesis and edema were greatly reduced in macrophage-depleted mice, lymphocyte-deficient Rag2(?/?) mice or CD4(+) T-cell-deficient mice. Mechanistically, T helper type 1 and T helper type 17 cells activate lesional macrophages to produce vascular endothelial growth factor-C, which promotes lymphangiogenesis, and inhibition of this mechanism suppressed not only early lymphangiogenesis, but also later development of lymphedema. Finally, we show that atorvastatin suppresses excessive lymphangiogenesis and lymphedema by inhibiting T helper type 1 and T helper type 17 cell activation. These results demonstrate that the interaction between CD4(+) T cells and macrophages is a potential therapeutic target for prevention of lymphedema after surgery.

Effects of dynamic shear and transmural pressure on wall shear stress sensitivity in collecting lymphatic vessels

Given the known mechanosensitivity of the lymphatic vasculature, we sought to investigate the effects of dynamic wall shear stress (WSS) on collecting lymphatic vessels while controlling for transmural pressure. Using a previously developed ex vivo lymphatic perfusion system (ELPS) capable of independently controlling both transaxial pressure gradient and average transmural pressure on an isolated lymphatic vessel, we imposed a multitude of flow conditions on rat thoracic ducts, while controlling for transmural pressure and measuring diameter changes. By gradually increasing the imposed flow through a vessel, we determined the WSS at which the vessel first shows sign of contraction inhibition, defining this point as the shear stress sensitivity of the vessel. The shear stress threshold that triggered a contractile response was significantly greater at a transmural pressure of 5 cmH2O (0.97 dyne/cm(2)) than at 3 cmH2O (0.64 dyne/cm(2)). While contraction frequency was reduced when a steady WSS was applied, this inhibition was reversed when the applied WSS oscillated, even though the mean wall shear stresses between the conditions were not significantly different. When the applied oscillatory WSS was large enough, flow itself synchronized the lymphatic contractions to the exact frequency of the applied waveform. Both transmural pressure and the rate of change of WSS have significant impacts on the contractile response of lymphatic vessels to flow. Specifically, time-varying shear stress can alter the inhibition of phasic contraction frequency and even coordinate contractions, providing evidence that dynamic shear could play an important role in the contractile function of collecting lymphatic vessels.

Lymphatic mapping and lymphedema surgery in the breast cancer patient

Upper limb lymphedema can be an unfortunate sequela following the oncologic treatment of breast cancer. The surgical treatment of lymphedema has had a recent renewed clinical interest paralleling innovative descriptions of surgical techniques and imaging modalities. In addition, an improved understanding of the physiology and pathophysiology of lymphedema has allowed improved translation to the clinical condition. Various surgical options exist to decrease the symptom-burden of upper limb lymphedema, including vascularized lymph node (VLN) transfer, lymphovenous bypass (LVB), liposuction, lymphatic grafting, and excisional procedures. Modern imaging techniques help to improve the consistency and accuracy of these surgical treatment options. A multi-modal treatment plan utilizing non-operative and surgical therapies has the potential to improve various factors related to overall patient quality of life. This review details all of the current operative treatment strategies and modern imaging modalities used in the treatment of lymphedema.

Laser CO2 treatment for vulvar lymphedema secondary to gynecological cancer therapy: A report of two cases and review of the literature

Vulvar lymphedema is an uncommon and disabling side-effect of pelvic lymphadenectomy and pelvic radiotherapeutic treatment for invasive genital cancer. Lymphorrhea, a complication of lymphedema, may be extremely distressing for patients due to the requirement to wear sanitary towels and as the pain and loss of elasticity of the vulvar skin and mucosa can cause discomfort during coitus. Surgical treatments of lymphorrhea and vulvar lymphedema secondary to gynecological cancer treatments remain controversial and are not currently considered to be the standard therapy. The present study reports two cases of vulvar lymphedema complicated by vulvar lymphorrhea in females who had undergone treatment for cervical and endometrial cancer, respectively; a review of the literature is also included. In the two present cases, vulvar lymphedemas were refractory to standard treatments, including decongestive therapy, manual lymph drainage, elastic bandaging, low-stretch bandaging, exercises and skin care. Laser CO₂ excision and vaporization of the whole skin and mucosal tissue of the vulva was successfully performed to treat the lymphorrhea and improve quality of life. Thus, the present two cases indicated that laser CO₂ surgery may present an additional therapy for the treatment of genital lymphedema that is refractory to other treatments.

Incidence and time path of lymphedema in sentinel node negative breast cancer patients: a systematic review

OBJECTIVE

To systematically assess the incidence/prevalence and time path of lymphedema in patients with sentinel node-negative breast cancer.

DATA SOURCES

A systematic literature search up to November 2013 was performed using 4 different electronic databases: PubMed, Embase, Cochrane Clinical Trials, and Web of Science.

STUDY SELECTION

Inclusion criteria were as follows: (1) research studies that included breast cancer patients who were surgically treated using the sentinel lymph node biopsy (SLNB) technique; (2) sentinel node-negative patients; (3) studies that investigated lymphedema as a primary or secondary outcome; (4) data extraction for the incidence or time path of lymphedema was possible; and (5) publication date starting from January 1, 2001. Exclusion criteria were as follows: (1) reviews or case studies; (2) patients who had an SLNB followed by an axillary lymph node dissection (ALND); (3) results of ALND patients and SLNB patients not described separately; and (4) studies not written in English.

DATA EXTRACTION

After scoring the methodological quality of the selected studies, the crude data concerning the incidence of lymphedema were extracted. Data concerning the time points and the incidence of lymphedema were also extracted.

DATA SYNTHESIS

Twenty-eight articles were included, representing 9588 SLNB-negative patients. The overall incidence of lymphedema in patients with sentinel node-negative breast cancer ranged from 0% to 63.4%. The studies that have assessed lymphedema at predefined time points, instead of a mean follow-up time, demonstrated an incidence range at ≤3, 6, 12, 18, or >18 months postsurgery of 3.2% to 5%, 2% to 10%, 3% to 63.4%, 6.6% to 7%, and 6.9% to 8.2%, respectively.

CONCLUSIONS

In SLNB patients, lymphedema is still a problem, mostly occurring 6 to 12 months after surgery. Because of different assessments and criteria, there is a wide range in incidence. Clear definitions of lymphedema are absolutely necessary to tailor therapy.

Emerging trends in the pathophysiology of lymphatic contractile function

Lymphatic contractile dysfunction is central to a number of pathologies that affect millions of people worldwide. Due to its critical role in the process of inflammation, a dysfunctional lymphatic system also compromises the immune response, further exacerbating a number of inflammation related diseases. Despite the critical physiological functions accomplished by the transport of lymph, a complete understanding of the contractile machinery of the lymphatic system lags far behind that of the blood vasculature. However, there has been a surge of recent research focusing on different mechanisms that underlie both physiological and pathophysiological aspects of lymphatic contractile function. This review summarizes those emerging paradigms that shed some novel insights into the contractile physiology of the lymphatics in normal as well as different disease states. In addition, this review emphasizes the recent progress made in our understanding of various contractile parameters and regulatory elements that contribute to the normal functioning of the lymphatics.