Pathophysiology of aged lymphatic vessels

MR Imaging of Neurofluids in the Developing Brain

The different fluid compartments in the developing brain work together to facilitate the delivery of nutrients, neurotransmitters, and neuromodulators. The cerebrospinal fluid and interstitial fluid are essential for clearing macromolecules from the brain, a process that involves the recently discovered meningeal lymphatics. Disruptions in these interactions can hinder normal brain development. Additionally, alterations in systemic fluid dynamics may contribute to neurologic complications, highlighting the need for a more holistic approach to understanding and treating neurologic diseases. MR imaging techniques show potential for detecting these pathologic processes in pediatric neurologic disorders.

Protective Factors Associated with Normal Lymphatic Function After Axillary Lymph Node Dissection for Breast Cancer Treatment

BACKGROUND

Risk factors associated with developing lymphedema following axillary lymph node dissection (ALND) are well-described in the literature. However, lymphedema diagnosis criteria is arbitrary and can vary between studies. This study instead aims to identify protective factors associated with normal lymphatic function after ALND for treatment of breast cancer.

METHODS

This was a prospective study of women treated with unilateral ALND for breast cancer between 2020 and 2023. Patients with normal lymphatic function were defined as meeting all of four criteria: <10% arm volume change from baseline, <10 bioimpedance change from baseline, no compression use, and Stage 0 on ICG lymphography at one year follow-up. All other patients were classified as having abnormal lymphatic function. Univariable and multivariable logistic regression were used to examine variables possibly associated with normal lymphatic function.

RESULTS

Of 150 patients with 1-year follow-up, 39 patients (26%) had normal lymphatic function and 111 patients (74%) had abnormal lymphatic function. On multivariable analysis, immediate lymphatic reconstruction (ILR) and younger age were significantly associated with normal lymphatic function. The odds of normal lymphatic function in patients who had ILR were 2.79 times higher than that of patients who did not undergo ILR (odds ratio [OR] = 2.79, 95% confidence interval [CI] = 1.23-6.69, p = 0.017). Meanwhile, increased age was associated with decreased odds of normal lymphatic function (OR = 0.93, 95% CI = 0.89-0.97, p = 0.001).

CONCLUSIONS

Immediate lymphatic reconstruction and younger age are significantly associated with normal lymphatic function 1 year after ALND. These findings suggest that undergoing ILR may be protective against developing breast cancer-related lymphedema.

Young lung cancer patients undergoing surgery: Comparison of clinicopathological characteristics and outcomes in patients aged ≤50 years versus >50 years

Objective

We investigated clinicopathologic characteristics, overall survival (OS), and locoregional recurrence-free survival of young surgical patients with non-small cell lung cancer.

Methods

Retrospective review of an institutional database of patients aged 50 years or younger undergoing resection for non-small cell lung cancer between January 1995 and March 2022. A control group of patients older than age 50 years was selected by stratified random sampling. Relevant characteristics were compared with Wilcoxon rank sum,χ,2 and Fisher exact tests. Propensity-score weighting was used to control for confounders. OS and locoregional recurrence-free survival were analyzed with Kaplan-Meier and Cox proportional hazards regression.

Results

We identified 196 patients aged 50 years or younger and 232 patients older than age 50 years. Median age was 46 years (interquartile range, 43-49 years) in the younger group and 69 years (interquartile range, 63-74 years) in the older group. Younger patients were more often women, non-White, and with fewer comorbidities. They more often presented with symptoms, stage III or IV disease, and more often received neoadjuvant therapy. In unweighted analysis, younger patients showed superior OS (log-rank P < .0001). After propensity score weighting for procedure type, histologic type, Charlson Comorbidity Index, and smoking status, there was no significant difference in OS at 5 years between younger and older groups (70.62% vs 72.99%; weighted log-rank P = .084). Younger patients showed superior OS (weighted log-rank P = .0006) and locoregional recurrence-free survival (weighted log-rank P = .017) for clinical stage I, but not any other stage. lymphovascular invasion was an independent risk factor for worsened OS and locoregional recurrence-free survival across ages.

Conclusions

Recognizing lung cancer as a differential diagnosis for patients aged 50 years or younger is crucial because this group shows superior outcomes for stage I disease. Lymphovascular invasion is an independent prognostic risk factor across age groups.

Factors associated with bilateral sentinel lymph node mapping failure using indocyanine green in patients with apparent early-stage cervical cancer: An Italian retrospective multi-center study

OBJECTIVE

The primary aim of this study was to assess the factors associated with bilateral mapping failure in patients with apparent early-stage cervical cancer undergoing sentinel lymph node (SLN) biopsy using indocyanine green (ICG). Secondary aims were sensitivity, negative predictive value and lymph node recurrence.

METHODS

Retrospective multi-center study. Patients with cervical cancer apparent FIGO stage IA1 to IIA2, treated with primary surgery between 04/2015 and 12/2023 and undergoing SLN mapping attempt with ICG injection, were included. Appropriate statistical analysis was performed to assess study endpoints. Timeframe was divided in first period 04/2015-12/2019 and second period 01/2020-12/2023.

RESULTS

618 patients were included. Bilateral SLN mapping was achieved in 531 (85.9 %) women (36 of them, 5.8 %, underwent cervical re-injection of ICG). SLN unilateral mapping and mapping failure was observed in 71 (11.5 %) and 16 (2.6 %), respectively. The sensitivity, negative predictive value and accuracy were 85.9 %, 98.1 % and 98.3 %, respectively. False negative rate was 4/68 (5.9 %) in patients with unilateral mapping versus 6/316 (1.9 %) in those with bilateral mapping (p = 0.061). BMI>30 (p = 0.001) and pathologic tumor diameter >20 mm (p = 0.023) were the only factors independently associated with bilateral SLN mapping failure. ICG re-injection increased the rate of bilateral SLN detection from 81.3 % to 85.9 %. The rate of bilateral detection was 82.8 % versus 88.3 % in the first versus second study period, respectively (p = 0.061). 3-year DFS and OS in all patients were 89.7 % and 98.2 %, respectively. Seven patients (1.2 %) had lymph node recurrence in the group of any SLN mapping versus 1 (6.3 %) in no mapping group (p = 0.190).

CONCLUSION

High BMI and larger tumors were associated with bilateral SLN mapping failure using ICG. The ICG cervical re-injection increased the rate of bilateral mapping. No lymph node recurrence difference was found in patients undergoing SLN mapping versus patients with mapping failure.

Predictors of the diuretic response in acute decompensated heart failure patients with severe aortic stenosis: sub-analysis of the LOHAS registry

For severe aortic stenosis (AS) patients awaiting valve replacement, managing acute decompensated heart failure (ADHF) is crucial due to poor prognosis. The LOHAS registry evaluated the effect of tolvaptan in patients (mean age: 85 years) with severe AS and ADHF, demonstrating stable hemodynamics and sufficient diuresis. We investigated predictors of rapid successful decongestion. In the LOHAS study, eligible patients received tolvaptan (7.5 mg) on day 1 plus standard ADHF treatments. Patients were divided based on decongestion achievement on day 4. Of 59 enrolled, 35 (59%) achieved decongestion (decongestion group), and 24 (41%) remained congested (congestion group). Changes in body weight, renal function, and hemodynamics were comparable between groups over the first 4 days. However, the maximum inferior vena cava (IVC) diameter at admission was significantly larger in the decongestion group than the congestion group (12.6 ± 6.3 vs. 7.6 ± 4.8 mm, p = 0.007). ROC analysis revealed a cut-off of 11 mm for maximum IVC diameter to predict decongestion on day 4 (AUC: 0.73, 95% CI 0.58-0.88). In-hospital mortality was lower in the decongestion group (0% vs. 13%, p = 0.06). In conclusion, in this high-risk severe AS and ADHF population, adding tolvaptan to standard therapy may rapidly improve decompensation if patients have a sufficiently expanded IVC at admission. Maximum IVC diameter could predict successful decongestion with tolvaptan.

Unravelling sources of variability on rocuronium pharmacokinetics: Implications for prolonged recovery in older patients

AIMS

Residual neuromuscular blockade (RNB) commonly occurs when using neuromuscular blockers and increases the risk for pulmonary complications, such as airway obstruction and severe hypoxemia, in extubated patients. Rocuronium exhibits a high variability in recovery time, contributing to an increased risk for RNB. This study aimed to identify and characterize the sources of variability in rocuronium exposure and response via a population pharmacokinetic/pharmacodynamic (PK/PD) analysis and to apply the developed PK/PD model to investigate clinical implications.

METHODS

A nonlinear mixed-effect model was developed for rocuronium in patients undergoing general anaesthesia, using doses of 0.3-1.2 mg/kg. Plasma concentrations and the neuromuscular block (train of four ratio) were assessed up to 6 h after dosing. The influence of age, body mass index, renal function and sex on PK and PD was explored. Simulations were performed to predict the recovery time.

RESULTS

A two-compartment model with linear elimination and an indirect sigmoid I-max model was used to describe PK and PD. The transfer rate into the periphery increases with age. The predicted recovery time was significantly longer in older subjects aged 85 years (median: 2.8 h; interquartile range [IQR]: 2.18-4.0) compared to young adults aged 25 years (median: 2.5 h; IQR: 2.0-3.1) following single bolus administrations of doses ≥ 0.7 mg/kg.

CONCLUSIONS

Our findings suggest that older patients take slightly longer to recover than younger adults due to an age-dependent increase in tissue uptake. However, a priori dose adjustments for rocuronium in older patients are not feasible, since age contribution is overshadowed by the overall variability in the recovery time.

External Validation of a 5-Factor Risk Model for Breast Cancer-Related Lymphedema

Importance

Secondary lymphedema is a common, harmful side effect of breast cancer treatment. Robust risk models that are externally validated are needed to facilitate clinical translation. A published risk model used 5 accessible clinical factors to predict the development of breast cancer-related lymphedema; this model included a patient's mammographic breast density as a novel predictive factor.

Objective

To investigate the external validity of a previously reported 5-factor model by applying it to an independent cohort of patients with breast cancer.

Design, Setting, and Participants

This prognostic study collected data on a longitudinal cohort of patients with predominantly early-stage breast cancer treated with curative intent at the Princess Margaret Cancer Centre in Toronto, Canada between February 1, 2010, and July 31, 2014, with a median (IQR) follow-up of 4.3 (2.4-7.6) years. The 5 factors (age, body mass index, breast density, nodal burden, and use of axillary lymph node dissection [ALND]) were used as input into the established regression-based model. The analysis was performed from July 2 through August 29, 2024.

Exposure

Lymphedema after breast cancer treatment.

Main Outcomes and Measures

Lymphedema-free survival (LFS) was analyzed using Kaplan-Meier analysis, and sensitivity, specificity, and accuracy performance metrics of predicting breast cancer-related lymphedema were calculated.

Results

A total of 101 female patients (median [IQR] age, 54.8 [48.8-62.3] years) were included in the analysis. These patients had localized or locoregional breast cancer treated with primary lumpectomy (90 [89%]) or mastectomy (11 [11%]); 75 (74%) had no axillary biopsy or sentinel lymph node biopsy; 26 (26%) had undergone ALND; and 38 (38%) had received chemotherapy, 101 (100%) received radiotherapy, and 64 (63%) received hormone therapy. Kaplan-Meier analysis showed a 2-year LFS of 97.5% (95% CI, 94.0%-100.0%) vs 65.0% (95% CI, 47.1%-89.7%) for the low- vs high-risk groups as defined by the 5-factor model (P < .001). The model sensitivity was 0.83 (95% CI, 0.52-0.98), specificity was 0.89 (95% CI, 0.80-0.94), and accuracy was 0.88 (95% CI, 0.80-0.94) for predicting breast cancer-related lymphedema.

Conclusions and Relevance

These findings validate the performance of a 5-factor risk model for its prediction of 2-year LFS. Future clinical translation of this model can help with identifying patients at the highest risk of breast cancer-related lymphedema to facilitate closer surveillance and/or preventive management to improve health outcomes and quality of life.

The emerging importance of lymphangiogenesis in aging and aging-associated diseases

Lymphatic aging represented by cellular and functional changes, is involved in increased geriatric disorders, but the intersection between aging and lymphatic modulation is less clear. Lymphatic vessels play an essential role in maintaining tissue fluid homeostasis, regulating immune function, and promoting macromolecular transport. Lymphangiogenesis and lymphatic remodeling following cellular senescence and organ deterioration are crosslinked with the progression of some lymphatic-associated diseases, e.g., atherosclerosis, inflammation, lymphoedema, and cancer. Age-related detrimental tissue changes may occur in lymphatic vessels with diverse etiologies, and gradually shift towards chronic low-grade inflammation, so-called inflammaging, and lead to decreased immune response. The investigation of the relationship between advanced age and organ deterioration is becoming an area of rapidly increasing significance in lymphatic biology and medicine. Here we highlight the emerging importance of lymphangiogenesis and lymphatic remodeling in the regulation of aging-related pathological processes, which will help to find new avenues for effective intervention to promote healthy aging.

Lymphatic embolization for early post-operative lymphatic leakage after radical cystectomy for bladder cancer

BACKGROUND AND OBJECTIVE

Although radical cystectomy (RC) with pelvic lymph node dissection (PLND) is the standard treatment of muscle invasive bladder cancer, it may cause lymphatic leakage. Recent studies describe lymphatic embolization (LE) as an option to manage post-operative lymphatic leakage. Hence, this study evaluated the outcome of LE in patients receiving RC and analyzed factors associated with outcomes.

METHODS

This was a retrospective analysis of patients who underwent LE after RC for bladder cancer between August 2017 and June 2023. The data was assessed for analysis at January 2024. The patients were divided into a clinical success group and a clinical failure group. Clinical failure was defined as the following: 1) those who required drainage catheter placement >7 days after LE, 2) those who needed re-intervention before catheter removal, and 3) those who experienced adverse events associated with LE. Logistic regression analysis was performed to identify the factors associated with outcomes of LE.

KEY FINDINGS AND LIMITATIONS

We analyzed 45 patients who underwent LE after RC. Twenty-eight (62.2%) patients were identified as clinically successful. Four patients required re-embolization, but none required more than two sessions of intervention. Three patients experienced lymphatic complications after LE. In multivariable analysis, maximal daily drainage volume of >1,000 mL/day (odds ratio [OR] = 4.729, 95% confidence interval [CI]: 1.018-21.974, p = 0.047) and diabetes mellitus (DM) (OR = 4.571, 95% CI: 1.128-18.510, p = 0.033) were factors associated with LE outcome.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Our results suggest LE as a potentially effective procedure for controlling post-operative lymphatic leaks after RC, with few minor side effects. Patients exceeding a daily drainage of 1,000mL/day or with a medical history of DM have a higher risk for re-intervention and clinical failure after LE.

Aging and physiological barriers: mechanisms of barrier integrity changes and implications for age-related diseases

The phenomenon of compartmentalization is one of the key traits of life. Biological membranes and histohematic barriers protect the internal environment of the cell and organism from endogenous and exogenous impacts. It is known that the integrity of these barriers decreases with age due to the loss of homeostasis, including age-related gene expression profile changes and the abnormal folding/assembly, crosslinking, and cleavage of barrier-forming macromolecules in addition to morphological changes in cells and tissues. The critical molecular and cellular mechanisms involved in physiological barrier integrity maintenance and aging-associated changes in their functioning are reviewed on different levels: molecular, organelle, cellular, tissue (histohematic, epithelial, and endothelial barriers), and organ one (skin). Biogerontology, which studies physiological barriers in the aspect of age, is still in its infancy; data are being accumulated, but there is no talk of the synthesis of complex theories yet. This paper mainly presents the mechanisms that will become targets of anti-aging therapy only in the future, possibly: pharmacological, cellular, and gene therapies, including potential geroprotectors, hormetins, senomorphic drugs, and senolytics.

Dynamics of Endothelial Cell Diversity and Plasticity in Health and Disease

Endothelial cells (ECs) are vital structural units of the cardiovascular system possessing two principal distinctive properties: heterogeneity and plasticity. Endothelial heterogeneity is defined by differences in tissue-specific endothelial phenotypes and their high predisposition to modification along the length of the vascular bed. This aspect of heterogeneity is closely associated with plasticity, the ability of ECs to adapt to environmental cues through the mobilization of genetic, molecular, and structural alterations. The specific endothelial cytoarchitectonics facilitate a quick structural cell reorganization and, furthermore, easy adaptation to the extrinsic and intrinsic environmental stimuli, known as the epigenetic landscape. ECs, as universally distributed and ubiquitous cells of the human body, play a role that extends far beyond their structural function in the cardiovascular system. They play a crucial role in terms of barrier function, cell-to-cell communication, and a myriad of physiological and pathologic processes. These include development, ontogenesis, disease initiation, and progression, as well as growth, regeneration, and repair. Despite substantial progress in the understanding of endothelial cell biology, the role of ECs in healthy conditions and pathologies remains a fascinating area of exploration. This review aims to summarize knowledge and concepts in endothelial biology. It focuses on the development and functional characteristics of endothelial cells in health and pathological conditions, with a particular emphasis on endothelial phenotypic and functional heterogeneity.

Impact of risk factors, early rehabilitation and management of lymphedema associated with breast cancer: a retrospective study of breast Cancer survivors over 5 years

BACKGROUND

Breast cancer-related lymphedema (BCRL) is a potentially disabling and often irreversible consequence of breast cancer treatment, caused by the mechanical incompetence of the lymphatic system, resulting in reduced drainage capacity and functional overload due to an excessive volume of interstitial fluid surpassing the system's transport capacity in the arm. We wanted to determine the impact and explore the differences in independent risk factors for the occurrence of BCRL; incidence of BCRL over a five-year period at the Institute of Oncology Vojvodina in Sremska Kamenica and to answer the research question regarding the influence of the prehabilitation program on the overall incidence of BCRL during the observed five-year period.

METHODS

From 2014 to 2018, a retrospective study was conducted at the Institute of Oncology of Vojvodina in Sremska Kamenica, analyzing female patients who had undergone breast cancer surgery.

RESULTS

The study included 150 breast cancer patients who developed secondary lymphedema following surgery with the mean age of 59.2 ± 11.3 years. Fluctuations in hospitalization rates were observed over the five-year period, with the highest number of admissions in 2014 (24.0%) and a decline in 2018 (14.0%). The most common surgical procedure performed was left quadrantectomy (24.0%), followed by right quadrantectomy (20.0%) and left amputation (15.3%). The mean number of removed lymph nodes was 15.2 ± 6.1, with no statistically significant association between the number of removed lymph nodes and the manifestation of secondary lymphedema. The severity of secondary lymphedema varied based on patient age, with a higher incidence of moderate and severe lymphedema observed in patients aged 61 years and older. Patients who underwent radical surgery were more likely to experience severe lymphedema compared to those who had conservative surgery, although this difference was not statistically significant.

CONCLUSION

In our study, the type of surgery, elapsed time since surgery, and the number of removed lymph nodes were not influencing factors for the occurrence of BCRL. However, concerning its severity, a greater number of systemic therapy modalities combined with radiotherapy were associated with a more frequent occurrence of mild and moderate BCRL. Also, the severity of BCRL varied among different age groups, with a higher incidence of moderate and severe lymphedema observed in patients aged 61 years and older. Ultimately, improving the quality of life for individuals affected by secondary lymphedema remains a crucial goal in the field of oncology.

The nasal lymphatic route of CSF outflow: implications for neurodegenerative disease diagnosis and monitoring

Cerebrospinal fluid (CSF) plays a crucial role in the brain's lymphatics as it traverses the central nervous system (CNS). Its primary function is to facilitate the outward transport of waste. Among the various CSF outflow pathways, the route through the cribriform plate along the olfactory nerves stands out as the most predominant. This review describes the outflow pathway of CSF into the nasal lymphatics. Additionally, we examine existing studies to describe mutual influences observed between the brain and extracranial regions due to this outflow pathway. Notably, pathological conditions in the CNS often influence CSF outflow, leading to observable changes in extracranial regions. The established connection between the brain and the nose is significant, and our review underscores its potential relevance in monitoring CNS ailments, including neurodegenerative diseases. Considering that aging - the most significant risk factor for the onset of neurodegeneration - is also a principal factor in CSF turnover alterations, we suggest a novel approach to studying neurodegenerative diseases in therapeutic terms.

Aging of lymphoid stromal architecture impacts immune responses

The secondary lymphoid organs (SLOs) undergo structural changes with age, which correlates with diminishing immune responses against infectious disease. A growing body of research suggests that the aged tissue microenvironment can contribute to decreased immune function, independent of intrinsic changes to hematopoietic cells with age. Stromal cells impart structural integrity, facilitate fluid transport, and provide chemokine and cytokine signals that are essential for immune homeostasis. Mechanisms that drive SLO development have been described, but their roles in SLO maintenance with advanced age are unknown. Disorganization of the fibroblasts of the T cell and B cell zones may reduce the maintenance of naïve lymphocytes and delay immune activation. Reduced lymphatic transport efficiency with age can also delay the onset of the adaptive immune response. This review focuses on recent studies that describe age-associated changes to the stroma of the lymph nodes and spleen. We also review recent investigations into stromal cell biology, which include high-dimensional analysis of the stromal cell transcriptome and viscoelastic testing of lymph node mechanical properties, as they constitute an important framework for understanding aging of the lymphoid tissues.

Battle of the milky way: Lymphatic targeted drug delivery for pathogen eradication

Many viruses, bacteria, and parasites rely on the lymphatic system for survival, replication, and dissemination. While conventional anti-infectives can combat infection-causing agents in the bloodstream, they do not reach the lymphatic system to eradicate the pathogens harboured there. This can result in ineffective drug exposure and reduce treatment effectiveness. By developing effective lymphatic delivery strategies for antiviral, antibacterial, and antiparasitic drugs, their systemic pharmacokinetics may be improved, as would their ability to reach their target pathogens within the lymphatics, thereby improving clinical outcomes in a variety of acute and chronic infections with lymphatic involvement (e.g., acquired immunodeficiency syndrome, tuberculosis, and filariasis). Here, we discuss approaches to targeting anti-infective drugs to the intestinal and dermal lymphatics, aiming to eliminate pathogen reservoirs and interfere with their survival and reproduction inside the lymphatic system. These include optimized lipophilic prodrugs and drug delivery systems that promote lymphatic transport after oral and dermal drug intake. For intestinal lymphatic delivery via the chylomicron pathway, molecules should have logP values >5 and long-chain triglyceride solubilities >50 mg/g, and for dermal lymphatic delivery via interstitial lymphatic drainage, nanoparticle formulations with particle size between 10 and 100 nm are generally preferred. Insight from this review may promote new and improved therapeutic solutions for pathogen eradication and combating infective diseases, as lymphatic system involvement in pathogen dissemination and drug resistance has been neglected compared to other pathways leading to treatment failure.

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

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Risk of lymphadenopathy from SARS-CoV-2 vaccination in Korea: a self-controlled case series analysis

OBJECTIVES

To assess the risk of lymphadenopathy following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination.

METHODS

A self-controlled case series design was used to determine whether the risk of lymphadenopathy was higher in the 1-day to 42-day risk interval after coronavirus disease 2019 (COVID-19) vaccination compared to the control period. In addition, subgroup analyses were conducted according to baseline characteristics, time since vaccination, and sensitivity analyses adjusted for the length of the risk interval.

RESULTS

The risk of developing lymphadenopathy in the risk interval (1-42 days) after COVID-19 vaccination compared to the control period was significantly increased, with a relative incidence (RI) of 1.17 (95% confidence interval [CI], 1.17 to 1.18) when the first, second, and third doses were combined. The RI was greater on the day of vaccination (1.47; 95% CI, 1.44 to 1.50). In subgroup analyses by baseline characteristics, a significantly increased risk or trend toward increased risk was observed in most subgroups except for those aged 70 years and older, with a significant increase in risk in younger individuals, those with a Charlson's comorbidity index <5, and those who received mRNA vaccines (mRNA-1273>BNT162b2). Within the 1-day to 42-day post-dose risk period, the relative risk was highest during the 1-day to 7-day post-dose period (1.59; 95% CI, 1.57 to 1.60) compared to the control period, and then the risk declined. In the sensitivity analysis, we found that the longer the risk window, the smaller the RI.

CONCLUSIONS

SARS-CoV-2 vaccination is associated with a statistically significant increase in the risk of lymphadenopathy, and this risk was observed only with mRNA vaccines.

Signaling mechanisms underlying lymphatic vessel dysfunction in skin aging and possible anti-aging strategies

Aging-related skin diseases are gradually increasing due to the imbalance of cutaneous homeostasis in the aging population. Skin aging-induced inflammation promotes systemic inflammation and may lead to whole-body aging. Lymphatic vessels play an important role in maintaining fluid and homeostasis balance. In intrinsically aged skin, the number of lymphatic vessels decrease and their functions decline, which is related to the reduced adhesion junctions between lymphatic endothelial cells, particularly VE-cadherin. VEGFC/VEGFR-3 signal pathway plays an important role in remodeling and expansion of lymphatic vessels; the downregulation of this pathway contributes to the dysfunction of lymphatic vessels. Meanwhile, we proposed some additional mechanisms. Decline of the pumping activity of lymphatic vessels might be related to age-related changes in extracellular matrix, ROS increase, and eNOS/iNOS disturbances. In extrinsically aged skin, the hyperpermeability of lymphatic vessels results from a decrease in endothelial-specific tight junction molecules, upregulation of VEGF-A, and downregulation of the VEGFC/VEGFR-3 signaling pathway. Furthermore, some of the Phyto therapeutics could attenuate skin aging by modulating the lymphatic vessels. This review summarized the lymphatic vessel dysfunction in skin aging and anti-aging strategies based on lymphatic vessel modulation.

The lymphatic system: a pathway for meta-inflammation in permafrost immunity

The lymphatic system is the anatomical substratum of immunity. Lymphatics collect tissue exudates, which contain cell debris, peptides, micronutrients and pathogens, as well as immune naive and memory effector cells from the body tissues and organs into the lymph. Lined by endothelial cells cemented together by tight junctions to ensure their impermeability, lymphatics contain valves that prevent the backward flow of the lymph as it moves forward toward the right and left venous angles, the anatomical site of confluence with the venous blood. Meta-inflammation increases the permeability of lymphatics, rendering the elderly more susceptible to novel and ancient airborne viruses released by melting glaciers and permafrost. Simple public health protocols (e.g., mask-wearing, quarantine) are essential to minimize colliding epidemics/pandemics, and favor permafrost immunity.

Modified Frailty Index and Albumin-Fibrinogen Ratio Predicts Postoperative Seroma After Laparoscopic TAPP

Background

Postoperative seroma is the most common minor complication after inguinal hernia repair surgery and can have negative consequences. The objective of this study was to identify potential risk factors for postoperative seroma.

Methods

This study consecutively included 354 elderly patients with inguinal hernia who underwent laparoscopic Transabdominal preperitoneal Patch Plasty (TAPP). Seroma diagnosis was conducted by the same experienced surgeon based on the physical examinations combined with ultrasound. Risk factors for seroma were identified through univariate analysis and subsequently included in the binary multivariate logistic regression model.

Results

A total of 40 patients experienced postoperative complications of seroma, with an incidence rate of 11.3% (40/354). The binary logistic regression analysis revealed that obesity (OR: 2.98, 95% CI: 1.20-7.41, P = 0.018), disease duration ≥ 4.5 years (OR: 4.88, 95% CI: 2.14-11.18, P < 0.001), albumin-fibrinogen ratio (AFR) level < 9.25 (OR: 6.13, 95% CI: 2.00-18.76, P = 0.001), and modified frailty index (mFI) score ≥ 0.225 (OR: 6.38, 95% CI: 2.69-15.10, P < 0.001) were four independent risk factors for postoperative seroma.

Conclusion

Obesity, prolonged disease duration, decreased AFR level, and increased mFI score independently predict postoperative seroma after laparoscopic TAPP.

Intrathecal [64Cu]Cu-albumin PET reveals age-related decline of lymphatic drainage of cerebrospinal fluid

Age-related cognitive decline is associated with dysfunctional lymphatic drainage of cerebrospinal fluid (CSF) through meningeal lymphatic vessels. In this study, intrathecal [64Cu]Cu-albumin positron emission tomography (PET) was applied in mice to evaluate lymphatic drainage of CSF and its variation with age. [64Cu]Cu-albumin PET was performed at multiple time points after intrathecal injection of [64Cu]Cu-albumin at an infusion rate of 700 nl/min in adult and aged mice (15-25 months old). CSF clearance and paravertebral lymph nodes were quantified after injection and during the stationary phase. Stationary phase of the next day followed the initial perturbed state by injection of 6 ul (1/7 of total CSF volume) and CSF clearance half-time from the subarachnoid space was 93.4 ± 19.7 and 123.3 ± 15.6 min in adult and aged mice (p = 0.01), respectively. While the % injected dose of CSF space were higher, the activity of the paravertebral lymph nodes were lower in the aged mice on the next day. [64Cu]Cu-albumin PET enabled us to quantify CSF-lymphatic drainage across all levels of brain spinal cords and to visualize and quantify lymph node activity due to CSF drainage. [64Cu]Cu-albumin PET revealed the age-related decrease of the lymphatic drainage of CSF due to this decreased drainage from the subarachnoid space, especially during the stationary phase, in aged mice.

The Enigmas of Lymphatic Muscle Cells: Where Do They Come From, How Are They Maintained, and Can They Regenerate?

Lymphatic muscle cell (LMC) contractility and coverage of collecting lymphatic vessels (CLVs) are integral to effective lymphatic drainage and tissue homeostasis. In fact, defects in lymphatic contractility have been identified in various conditions, including rheumatoid arthritis, inflammatory bowel disease, and obesity. However, the fundamental role of LMCs in these pathologic processes is limited, primarily due to the difficulty in directly investigating the enigmatic nature of this poorly characterized cell type. LMCs are a unique cell type that exhibit dual tonic and phasic contractility with hybrid structural features of both vascular smooth muscle cells (VSMCs) and cardiac myocytes. While advances have been made in recent years to better understand the biochemistry and function of LMCs, central questions regarding their origins, investiture into CLVs, and homeostasis remain unanswered. To summarize these discoveries, unexplained experimental results, and critical future directions, here we provide a focused review of current knowledge and open questions related to LMC progenitor cells, recruitment, maintenance, and regeneration. We also highlight the high-priority research goal of identifying LMC-specific genes towards genetic conditional- inducible in vivo gain and loss of function studies. While our interest in LMCs has been focused on understanding lymphatic dysfunction in an arthritic flare, these concepts are integral to the broader field of lymphatic biology, and have important potential for clinical translation through targeted therapeutics to control lymphatic contractility and drainage.

Targeting Synovial Lymphatic Function as a Novel Therapeutic Intervention for Age-Related Osteoarthritis in Mice

OBJECTIVE

The synovial lymphatic system (SLS) removes catabolic factors from the joint. Vascular endothelial growth factor C (VEGF-C) and its receptor, VEGFR-3, are crucial for lymphangiogenesis. However, their involvement in age-related osteoarthritis (OA) is unknown. This study was undertaken to determine whether the SLS and the VEGF-C/VEGFR-3 pathway contribute to the development and progression of age-related OA, using a murine model of naturally occurring joint disease.

METHODS

SLS function was assessed in the knees of young (3-month-old) and aged (19-24-month-old) male and female C57BL/6J mice via a newly established in vivo IVIS-dextran imaging approach, which, in addition to histology, was used to assess the effects of VEGF-C treatment on SLS function and OA pathology in aged mice. RNA-sequencing of synovial tissue was performed to explore molecular mechanisms of the disease in the mouse knee joints.

RESULTS

Results showed that aged mice had impaired SLS function, including decreases in joint clearance (mean T1/2 of signal intensity clearance, 2.8 hours in aged mice versus 0.5 hours in young mice; P < 0.0001), synovial influx (mean ± SD 1.7 ± 0.8% in aged mice versus 4.1 ± 1.9% in young mice; P = 0.0004), and lymph node draining capacity (mean ± SD epifluorescence total radiant intensity ([photons/second]/[μW/cm2 ]) 1.4 ± 0.8 in aged mice versus 3.7 ± 1.2 in young mice; P < 0.0001). RNA-sequencing of the synovial tissue showed that Vegf-c and Vegfr3 signaling genes were decreased in the synovium of aged mice. VEGF-C treatment resulted in improvements in SLS function in aged mice, including increased percentage of signal intensity joint clearance (mean ± SD 63 ± 9% in VEGF-C-treated aged mice versus 52 ± 15% in vehicle-treated aged mice; P = 0.012), increased total articular cartilage cross-sectional area (mean ± SD 0.38 ± 0.07 mm2 in VEGF-C-treated aged mice versus 0.26 ± 0.07 mm2 in vehicle-treated aged mice; P < 0.0001), and decreased percentage of matrix metallopeptidase 13-positive staining area within total synovial area in 22-month-old VEGF-C-treated mice versus 22-month-old vehicle-treated mice (mean ± SD decrease 7 ± 2% versus 4 ± 1%; P = 0.0004).

CONCLUSION

SLS function is reduced in the knee joints of aged mice due to decreased VEGF-C/VEGFR-3 signaling. VEGF-C treatment attenuates OA joint damage and improves synovial lymphatic drainage in aged mice. The SLS and VEGF-C/VEGFR-3 signaling represent novel physiopathologic mechanisms that could potentially be used as therapeutic targets for age-related OA.

Immediate lymphatic reconstruction for the prevention of breast cancer-related lymphedema: an experience highlighting the importance of lymphatic anatomy

Immediate lymphatic reconstruction (ILR) has become increasingly utilized for the prevention of breast cancer-related lymphedema (BCRL). A growing body of evidence has demonstrated the long-term efficacy of ILR in reducing the rate of BCRL. While certain risk factors for BCRL are well-recognized, such as axillary lymph node dissection, regional lymph node radiation, and elevated body mass index, other potential risk factors such as age and taxane-based chemotherapeutics remain under discussion. Our experience with ILR has highlighted an additional potential risk factor for BCRL. Lymphatic anatomy, specifically compensatory lymphatic channels that bypass the axilla, may play a largely underrecognized role in determining which patients will develop BCRL after ILR. Foundational anatomic knowledge has primarily been based on cadaveric studies that predate the twentieth century. Modern approaches to lymphatic anatomical mapping using indocyanine green lymphography have helped to elucidate baseline lymphatic anatomy and compensatory channels, and certain variations within these channels may act as anatomic risk factors. Therefore, the purpose of this review was to highlight ways in which variations in lymphatic anatomy can inform the application and improve the accessibility of this procedure. As ILR continues to advance and evolve, anatomical mapping of the lymphatic system is valuable to both the patient and lymphatic microsurgeon and is a critical area of future study.

Assessment of Meningeal Lymphatics in the Parasagittal Dural Space: A Prospective Feasibility Study Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging

OBJECTIVE

Meningeal lymphatic vessels are predominantly located in the parasagittal dural space (PSD); these vessels drain interstitial fluids out of the brain and contribute to the glymphatic system. We aimed to investigate the ability of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in assessing the dynamic changes in the meningeal lymphatic vessels in PSD.

MATERIALS AND METHODS

Eighteen participants (26-71 years; male:female, 10:8), without neurological or psychiatric diseases, were prospectively enrolled and underwent DCE-MRI. Three regions of interests (ROIs) were placed on the PSD, superior sagittal sinus (SSS), and cortical vein. Early and delayed enhancement patterns and six kinetic curve-derived parameters were obtained and compared between the three ROIs. Moreover, the participants were grouped into the young (< 65 years; n = 9) or older (≥ 65 years; n = 9) groups. Enhancement patterns and kinetic curve-derived parameters in the PSD were compared between the two groups.

RESULTS

The PSD showed different enhancement patterns than the SSS and cortical veins (P < 0.001 and P < 0.001, respectively) in the early and delayed phases. The PSD showed slow early enhancement and a delayed wash-out pattern. The six kinetic curve-derived parameters of PSD was significantly different than that of the SSS and cortical vein. The PSD wash-out rate of older participants was significantly lower (median, 0.09; interquartile range [IQR], 0.01-0.15) than that of younger participants (median, 0.32; IQR, 0.07-0.45) (P = 0.040).

CONCLUSION

This study shows that the dynamic changes of meningeal lymphatic vessels in PSD can be assessed with DCE-MRI, and the results are different from those of the venous structures. Our finding that delayed wash-out was more pronounced in the PSD of older participants suggests that aging may disturb the meningeal lymphatic drainage.

Risk factors for the development of severe breast cancer-related lymphedema: a retrospective cohort study

BACKGROUND

Severe lymphedema presents a challenge in terms of treatment due to the significant formation of scar tissue that accompanies it. The aim of this study was to identify intraoperative and preoperative risk factors of severe lymphedema and to develop a nomogram for estimating the risk of severe lymphedema within 3 years of surgery.

METHOD

Data was collected from a retrospective cohort of 326 patients with BCRL at the Zhejiang Cancer Hospital from November 2015 to November 2018. Univariate and multivariate logistic regression analysis was conducted to identify predictive indicators of severe lymphedema. A nomogram was developed to further improve the clinical applicability.

RESULTS

In the retrospective cohort, the ratio of severe/non-severe lymphedema within 3 years of surgery was 1:3. Independent risk factors for severe lymphedema were determined to be age, positive lymph nodes, interpectoral (Rotter's) lymph nodes (IPNs) dissection, and educational level. IPNs dissection was found to contribute greatly to the development of severe lymphedema with a higher odds ratio (7.76; 95% CI: 3.87-15.54) than other risk factors. A nomogram was developed by integrating age, positive lymph nodes, IPNs dissection, and educational level, which yielded a C-index of 0.810 and 0.681 in the training and validation cohort, respectively. This suggested a moderate performance of the nomogram in predicting the risk of severe lymphedema within 3 years of surgery. The cut-off values of the low-, medium- and high-risk probabilities were 0.0876 and 0.3498, and the severe lymphedema exhibited a significantly higher risk probability as compared with the non-severe lymphedema.

CONCLUSION

This study identified the risk factors of severe lymphedema and highlighted the substantial contribution of IPNs dissection to the severity of lymphedema.

Human collecting lymphatic glycocalyx identification by electron microscopy and immunohistochemistry

Blood flow is translated into biochemical inflammatory or anti-inflammatory signals based onshear stress type, by means of sensitive endothelial receptors. Recognition of the phenomenon is of paramount importance for enhanced insights into the pathophysiological processes of vascular remodeling. The endothelial glycocalyx is a pericellular matrix, identified in both arteries and veins, acting collectively as a sensor responsive to blood flow changes. Venous and lymphatic physiology is interconnected; however, to our knowledge, a lymphatic glycocalyx structure has never been identified in humans. The objective of this investigation is to identify glycocalyx structures from ex vivo lymphatic human samples. Lower limb vein and lymphatic vessels were harvested. The samples were analyzed by transmission electron microscopy. The specimens were also examined by immunohistochemistry. Transmission electron microscopy identified a glycocalyx structure in human venous and lymphatic samples. Immunohistochemistry for podoplanin, glypican-1, mucin-2, agrin and brevican characterized lymphatic and venous glycocalyx-like structures. To our knowledge, the present work reports the first identification of a glycocalyx-like structure in human lymphatic tissue. The vasculoprotective action of the glycocalyx could become an investigational target in the lymphatic system as well, with clinical implications for the many patients affected by lymphatic disorders.

Blood Markers of Biological Age Evaluates Clinic Complex Medical Spa Programs

BACKGROUND

Kivach Clinic has developed a special medical spa program to prevent aging-related conditions in metabolic, cardio-vascular, and neurological states. Spa programs modify diet, physical activity, and lymphatic drainage, as it deteriorates with aging. We investigated its influence on the blood markers of biological age of patients during their stay to objectify the potential of spa treatment for influencing the risk of age-related events.

METHODS

The artificial deep learning model Aging.ai 3.0 was based on blood parameters. The change in the biological age of 43 patients was assessed after their 14-day spa treatment at Kivach Clinic.

RESULTS

Biological age decreased in 29 patients (median decrease: 8 years, mean: 8.83 years), increased in 10 patients (median increase: 3 years, mean: 5.33 years) and remained unchanged in 4 patients. Overall mean values for the entire patient group were as follows: median value was -3 years, and mean was -4.79 ± 1.2 years (p-value = 0.00025, t-test).

CONCLUSIONS

The capability of specially selected medical spa treatment to reduce human biological age (assessed by Aging.AI 3.0) has been established.

Cellular Senescence as a Brake or Accelerator for Oncogenic Transformation and Role in Lymphatic Metastasis

Cellular senescence-the irreversible cell cycle arrest driven by a variety of mechanisms and, more specifically, the senescence-associated secretory phenotype (SASP)-is an important area of research in the context of different age-related diseases, such as cardiovascular disease and cancer. SASP factors play both beneficial and detrimental roles in age-related disease progression depending on the source of the SASPs, the target cells, and the microenvironment. The impact of senescence and the SASP on different cell types, the immune system, and the vascular system has been widely discussed. However, the impact of replicative or stress-induced senescence on lymphatic biology and pathological lymphangiogenesis remains underexplored. The lymphatic system plays a crucial role in the maintenance of body fluid homeostasis and immune surveillance. The perturbation of lymphatic function can hamper normal physiological function. Natural aging or stress-induced premature aging influences the lymphatic vessel structure and function, which significantly affect the role of lymphatics in tumor dissemination and metastasis. In this review, we focus on the role of senescence on lymphatic pathobiology, its impact on cancer, and potential therapeutic interventions to manipulate the aged or senescent lymphatic system for disease management.

Age as a risk factor for breast cancer-related lymphedema: a systematic review

PURPOSE

Breast cancer-related lymphedema (BCRL) has been widely reported in the medical literature. Various patient characteristics, including age, have been investigated as possible risk factors for this disease entity, but the existence and direction of the cause-and-effect relationship are still unclear. In this review, we aimed to evaluate the effect of age on development of BRCL.

METHODS

PubMed, Scopus, and Ovid MEDLINE were searched for relevant articles, which were found to be published between 1974 and 2020.

RESULTS

Twenty-six studies involving 19,396 patients were selected. The average age of patients was 54.9. 26 studies were included in the final analysis, and 13 articles reported no association between age and BCRL development.

CONCLUSIONS

Though studies presented different findings, the majority did not identify age as a risk factor for development of lymphedema. However, the level of evidence of individual studies was low. In this article, we call attention to the need for uniform design of lymphedema studies and diagnosis.

IMPLICATIONS FOR CANCER SURVIVORS

All patients should be informed and screened regularly for lymphedema during and after the treatment independent of their age.

Burden of lymphedema in long-term breast cancer survivors by race and age

BACKGROUND

Risk assessment for breast cancer-related lymphedema has emphasized upper-limb symptoms and treatment-related risk factors. This article examined breast cancer-related lymphedema after surgery, overall and in association with broader demographic and clinical features.

METHODS

The Carolina Breast Cancer Study phase 3 followed participants for breast cancer-related lymphedema from baseline (on average, 5 months after breast cancer diagnosis) to 7 years after diagnosis. Among 2645 participants, 552 self-reported lymphedema cases were identified. Time-to-lymphedema curves and inverse probability weighted conditional Cox proportional hazards model were used to evaluate whether demographics and clinical features were associated with breast cancer-related lymphedema.

RESULTS

Point prevalence of breast cancer-related lymphedema was 6.8% at baseline, and 19.9% and 23.8% at 2 and 7 years after diagnosis, respectively. Most cases had lymphedema in the arm (88%-93%), whereas 14% to 27% presented in the trunk and/or breast. Beginning approximately 10 months after diagnosis, younger Black women had the highest risk of breast cancer-related lymphedema and older non-Black women had the lowest risk. Positive lymph node status, larger tumor size (>5 cm), and estrogen receptor-negative breast cancer, as well as established risk factors such as higher body mass index, removal of more than five lymph nodes, mastectomy, chemotherapy, and radiation therapy, were significantly associated with increased hazard (1.5- to 3.5-fold) of lymphedema.

CONCLUSIONS

Findings highlight that hazard of breast cancer-related lymphedema differs by demographic characteristics and clinical features. These factors could be used to identify those at greatest need of lymphedema prevention and early intervention.

LAY SUMMARY

In this study, the aim was to investigate breast cancer-related lymphedema (BCRL) burden. This study found that risk of BCRL differs by race, age, and other characteristics.

Ocular Lymphatic and Glymphatic Systems: Implications for Retinal Health and Disease

Clearance of ocular fluid and metabolic waste is a critical function of the eye in health and disease. The eye has distinct fluid outflow pathways in both the anterior and posterior segments. Although the anterior outflow pathway is well characterized, little is known about posterior outflow routes. Recent studies suggest that lymphatic and glymphatic systems play an important role in the clearance of fluid and waste products from the posterior segment of the eye. The lymphatic system is a vascular network that runs parallel to the blood circulatory system. It plays an essential role in maintenance of fluid homeostasis and immune surveillance in the body. Recent studies have reported lymphatics in the cornea (under pathological conditions), ciliary body, choroid, and optic nerve meninges. The evidence of lymphatics in optic nerve meninges is, however, limited. An alternative lymphatic system termed the glymphatic system was recently discovered in the rodent eye and brain. This system is a glial cell-based perivascular network responsible for the clearance of interstitial fluid and metabolic waste. In this review, we will discuss our current knowledge of ocular lymphatic and glymphatic systems and their role in retinal degenerative diseases.

Lymphaticovenous Anastomosis for Treating Secondary Lower Limb Lymphedema in Older Patients-A Retrospective Cohort Study

Despite an increased incidence of secondary lower limb lymphedema (LLL) and severity of comorbidities with age, the impact of age on the effectiveness of lymphaticovenous anastomosis (LVA) in the older patients remains unclear. Methods: This retrospective cohort study enrolled older patients (age > 65 years) with secondary unilateral LLL. All patients underwent supermicrosurgical LVA. Demographic data and intraoperative findings including lymphatic vessel (LV) diameter, LV functionality (indocyanine green-enhanced and Flow positivity), and lymphosclerosis classification were recorded. Magnetic resonance volumetry was used for measuring preoperative and postoperative volume changes at 6 months and one year after LVA as primary and secondary endpoints. Results: Thirty-two patients (29 females/3 males) with a median age of 71.0 years [range, 68.0 to 76.3] were enrolled. The median duration of lymphedema was 6.4 [1.0 to 11.7] years. The median LV diameter was 0.7 [0.5 to 0.8] mm. The percentage of ICG-enhanced and Flow-positive LVs were 89.5% and 85.8%, respectively. The total percentage of suitable LVs (s0 and s1) for LVA based on lymphosclerosis classification was 75.9%. There were significant six-month and one-year post-LVA percentage volume reductions compared to pre-LVA volume (both p < 0.001). A significant reduction in cellulitis incidence was also noted after LVA (p < 0.001). No surgical or postoperative complications were found. Conclusion: Relief of secondary LLL was achievable through LVA in older patients who still possessed favorable LV characteristics, including larger LV diameters as well as a high proportion of functional LVs with a low grade of lymphosclerosis.

Structural and Functional Changes in Aged Skin Lymphatic Vessels

Lymphatic structure and function play a critical role in fluid transport, antigen delivery, and immune homeostasis. A dysfunctional lymphatic system is associated with chronic low-grade inflammation of peripheral tissues, poor immune responses, and recurrent infections, which are also hallmarks of aging pathology. Previous studies have shown that aging impairs lymphatic structure and function in a variety of organ systems, including the intestines and central nervous system. However, previous studies are mostly limited to qualitative analysis of lymphatic structural changes and quantification of intestinal collecting vessel contractile function. It is not clear whether decreased lymphatic function contributes to pathological conditions related to aging, nor how it affects the skin immune microenvironment. Further, the effects of aging on skin initial and collecting lymphatic vessels, dendritic cell (DC) migration, cutaneous lymphatic pumping, and VEGFR-3 signaling in lymphatic endothelial cells (LECs) have not been quantitatively analyzed. Here, using fluorescent immunohistochemistry and flow cytometry, we confirm that aging decreases skin initial and collecting lymphatic vessel density. Indocyanine green (ICG) lymphangiography and DC migration assays confirm that aging decreases both fluid pumping and cell migration via lymphatic vessels. At the cellular level, aging causes decreased VEGFR-3 signaling, leading to increased LEC apoptosis and senescence. Finally, we determined that aging causes decreased lymphatic production of chemokines and alters LEC expression of junctional and adhesion molecules. This in turn leads to increased peri-lymphatic inflammation and nitrosative stress that might contribute to aging pathology in a feed-forward manner. Taken together, our study, in addition to quantitatively corroborating previous findings, suggests diverse mechanisms that contribute to lymphatic dysfunction in aging that in turn exacerbate the pathology of aging in a feed-forward manner.

Single-cell transcriptomics of popliteal lymphatic vessels and peripheral veins reveals altered lymphatic muscle and immune cell populations in the TNF-Tg arthritis model

Background

Lymphatic dysfunction exists in tumor necrosis factor transgenic (TNF-Tg) mice and rheumatoid arthritis (RA) patients. While joint-draining TNF-Tg popliteal lymphatic vessels (PLVs) have deficits in contractility during end-stage arthritis, the nature of lymphatic muscle cells (LMCs) and their TNF-altered transcriptome remain unknown. Thus, we performed single-cell RNA-sequencing (scRNAseq) on TNF-Tg LMCs in PLVs efferent to inflamed joints versus wild-type (WT) controls.

Methods

Single-cell suspensions of PLVs were sorted for smooth muscle cells (SMCs), which was validated by Cspg4-Cre;tdTomato reporter gene expression. Single-cell RNA-seq was performed on a 10x Genomics platform and analyzed using the Seurat R package. Uniform Manifold Approximation and Projections (UMAPs) and Ingenuity Pathway Analysis software were used to assess cell clusters and functional genomics in WT vs. TNF-Tg populations.

Results

Fluorescent imaging of Cspg4-Cre;tdTomato vessels demonstrated dim PLVs and strong reporter gene expression in the adjacent superficial saphenous vein, which was corroborated by flow cytometry of LMCs and vascular smooth muscle cells (VSMCs) from these vessels. Due to their unique morphology, these populations could also be readily detected by scatter analysis of cells from non-fluorescent mice. Bioinformatics analysis of flow sorted WT and TNF-Tg cells identified 20 unique cell clusters that together were 22.4% LMCs, 15.0% VSMCs, and 62.6% non-muscle cells of 8879 total cells. LMCs and M2-macrophages were decreased, while inflammatory monocytes were increased in TNF-Tg lower limb vasculature. SMC populations were defined by Cald1, Tpm1, and Pdgfrb expression and were enriched in myofibroblast-like gene expression. TNF-Tg LMCs exhibited enhanced functional genomics associated with cell death, phagocyte recruitment, and joint inflammation. Among the most prominent TNF-induced genes in SMCs were Mmp3, Cxcl12, and Ccl19, and the most downregulated genes were Zbtb16, Galnt15, and Apod.

Conclusions

Single-cell RNA-seq can be used to investigate functional genomics of lower limb vasculature in mice. Our findings confirm the inflammatory transcriptome of TNF-Tg vessels and altered gene expression in SMC populations. This study further supports a potential role of mesenchymal stromal cells in inflammatory-erosive arthritis pathogenesis, and warrants future studies to define the effects of this TNF-altered transcriptome on PLV function and joint homeostasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02730-z.

The failure of a sentinel node biopsy due to an absence of nodal uptake of nuclear isotope in consecutive melanomas in a single patient – a physiological aberration

Nodal metastasis is an independent prognostic factor in patients with melanoma. Sentinel lymph node biopsy (SNB) is a recommended component of the management of patients with AJCC stage T1b or above. The dermal scar is injected with a Technetium-99 m (^99MTc) Nanocolloid, a radiotracer that drains into sentinel nodes to be identified on a preoperative SPECT/CT scan. Intraoperatively the sentinel nodes are located using a gamma probe and patent blue dye. A 79-year-old male was referred to the Plastics Outpatient Department for management of a biopsy proven pT4b melanoma on the right flank and a suspicious lesion on the right shoulder. He was scheduled for a SNB and wide local excision of the flank melanoma and excisional biopsy of the shoulder lesion. He received injections of ^99MTc Nanocolloid around the flank biopsy scar, however, preoperative, and intraoperative attempts to locate a node using radiological and surgical techniques were unsuccessful. The biopsy of the shoulder lesion sent for histopathology revealed a pT1b melanoma. A subsequent second SNB on the shoulder melanoma was unsuccessful, as ^99MTc Nanocolloid failed to drain into a sentinel node for a second time. The drainage function of lymphatic vessels declines with age however the complete failure of nodal uptake is exceptionally rare. Novel radiotracers such as ^99MTc Tilmanocept have shown superior lymph node tracking in recent tracers.

Angiotensin II Induces Cardiac Edema and Hypertrophic Remodeling through Lymphatic-Dependent Mechanisms

Cardiac lymphatic vessel growth (lymphangiogenesis) and integrity play an essential role in maintaining tissue fluid balance. Inhibition of lymphatic lymphangiogenesis is involved in cardiac edema and cardiac remodeling after ischemic injury or pressure overload. However, whether lymphatic vessel integrity is disrupted during angiotensin II- (Ang II-) induced cardiac remodeling remains to be investigated. In this study, cardiac remodeling models were established by Ang II (1000 ng/kg/min) in VEGFR-3 knockdown (Lyve-1Cre VEGFR-3f/−) and wild-type (VEGFR-3f/f) littermates. Our results indicated that Ang II infusion not only induced cardiac lymphangiogenesis and upregulation of VEGF-C and VEGFR-3 expression in the time-dependent manner but also enhanced proteasome activity, MKP5 and VE-cadherin degradation, p38 MAPK activation, and lymphatic vessel hyperpermeability. Moreover, VEGFR-3 knockdown significantly inhibited cardiac lymphangiogenesis in mice, resulting in exacerbation of tissue edema, hypertrophy, fibrosis superoxide production, inflammation, and heart failure (HF). Conversely, administration of epoxomicin (a selective proteasome inhibitor) markedly mitigated Ang II-induced cardiac edema, remodeling, and dysfunction; upregulated MKP5 and VE-cadherin expression; inactivated p38 MAPK; and reduced lymphatic vessel hyperpermeability in WT mice, indicating that inhibition of proteasome activity is required to maintain lymphatic endothelial cell (LEC) integrity. Our results show that both cardiac lymphangiogenesis and lymphatic barrier hyperpermeability are implicated in Ang II-induced adaptive hypertrophic remodeling and dysfunction. Proteasome-mediated hyperpermeability of LEC junctions plays a predominant role in the development of cardiac remodeling. Selective stimulation of lymphangiogenesis or inhibition of proteasome activity may be a potential therapeutic option for treating hypertension-induced cardiac remodeling.

Adipose tissue microenvironments during aging: Effects on stimulated lipolysis

Adipose tissue is a critical organ for nutrient sensing, energy storage and maintaining metabolic health. The failure of adipose tissue homeostasis leads to metabolic disease that is seen during obesity or aging. Local metabolic processes are coordinated by interacting microenvironments that make up the complexity and heterogeneity of the adipose tissue. Catecholamine-induced lipolysis, a critical pathway in adipocytes that drives the release of stored triglyceride as free fatty acid after stimulation, is impaired during aging. The impairment of this pathway is associated with a failure to maintain a healthy body weight, core body-temperature during cold stress or mount an immune response. Along with impairments in aged adipocytes, aging is associated with an accumulation of inflammation, immune cell activation, and increased dysfunction in the nervous and lymphatic systems within the adipose tissue. Together these microenvironments support the initiation of stimulated lipolysis and the transport of free fatty acid under conditions of metabolic homeostasis. However, during aging, the defects in these cellular systems result in a reduction in ability to stimulate lipolysis. This review will focus on how the immune, nervous and lymphatic systems interact during tissue homeostasis, review areas that are impaired with aging and discuss areas of research that are currently unclear.

Non-invasive MR imaging of human brain lymphatic networks with connections to cervical lymph nodes

Meningeal lymphatic vessels have been described in animal studies, but limited comparable data is available in human studies. Here we show dural lymphatic structures along the dural venous sinuses in dorsal regions and along cranial nerves in the ventral regions in the human brain. 3D T2-Fluid Attenuated Inversion Recovery magnetic resonance imaging relies on internal signals of protein rich lymphatic fluid rather than contrast media and is used in the present study to visualize the major human dural lymphatic structures. Moreover we detect direct connections between lymphatic fluid channels along the cranial nerves and vascular structures and the cervical lymph nodes. We also identify age-related cervical lymph node atrophy and thickening of lymphatics channels in both dorsal and ventral regions, findings which reflect the reduced lymphatic output of the aged brain.

Coagulation in Lymphatic System

The lymphatic system maintains homeostasis of the internal environment between the cells in tissues and the blood circulation. The coagulation state of lymph is determined by conditions of coagulation factors and lymphatic vessels. Internal obliteration, external compression or abnormally increased lymphatic pressure may predispose to localized lymphatic coagulation. In physiological conditions, an imbalance of antithrombin and thrombokinase reduces lymphatic thrombosis. However, the release of factor X by lymphatic endothelium injury may trigger coagulation casacade, causing blockage of lymphatic vessels and lymphedema. Heterogeneity of lymphatic vessels in various tissues may lead to distinct levels and patterns of coagulation in specific lymphatic vessels. The quantitative and qualitative measurement of clotting characteristic reveals longer time for clotting to occur in the lymph than in the blood. Cancer, infections, amyloidosis and lymph node dissection may trigger thrombosis in the lymphatic vessels. In contrast to venous or arterial thrombosis, lymphatic thrombosis has rarely been reported, and its actual prevalence is likely underestimated. In this review, we summarize the mechanisms of coagulation in lymphatic system, and discuss the lymphatic thrombosis-related diseases.

Aging-Related Cellular, Structural and Functional Changes in the Lymph Nodes: A Significant Component of Immunosenescence? An Overview

Aging affects all tissues and organs. Aging of the immune system results in the severe disruption of its functions, leading to an increased susceptibility to infections, an increase in autoimmune disorders and cancer incidence, and a decreased response to vaccines. Lymph nodes are precisely organized structures of the peripheral lymphoid organs and are the key sites coordinating innate and long-term adaptive immune responses to external antigens and vaccines. They are also involved in immune tolerance. The aging of lymph nodes results in decreased cell transport to and within the nodes, a disturbance in the structure and organization of nodal zones, incorrect location of individual immune cell types and impaired intercellular interactions, as well as changes in the production of adequate amounts of chemokines and cytokines necessary for immune cell proliferation, survival and function, impaired naïve T- and B-cell homeostasis, and a diminished long-term humoral response. Understanding the causes of these stromal and lymphoid microenvironment changes in the lymph nodes that cause the aging-related dysfunction of the immune system can help to improve long-term immune responses and the effectiveness of vaccines in the elderly.

Molecular Mechanisms of Neuroimmune Crosstalk in the Pathogenesis of Stroke

Stroke disrupts the homeostatic balance within the brain and is associated with a significant accumulation of necrotic cellular debris, fluid, and peripheral immune cells in the central nervous system (CNS). Additionally, cells, antigens, and other factors exit the brain into the periphery via damaged blood–brain barrier cells, glymphatic transport mechanisms, and lymphatic vessels, which dramatically influence the systemic immune response and lead to complex neuroimmune communication. As a result, the immunological response after stroke is a highly dynamic event that involves communication between multiple organ systems and cell types, with significant consequences on not only the initial stroke tissue injury but long-term recovery in the CNS. In this review, we discuss the complex immunological and physiological interactions that occur after stroke with a focus on how the peripheral immune system and CNS communicate to regulate post-stroke brain homeostasis. First, we discuss the post-stroke immune cascade across different contexts as well as homeostatic regulation within the brain. Then, we focus on the lymphatic vessels surrounding the brain and their ability to coordinate both immune response and fluid homeostasis within the brain after stroke. Finally, we discuss how therapeutic manipulation of peripheral systems may provide new mechanisms to treat stroke injury.

Correlation of older age with severity of lymphedema in breast cancer survivors: A systematic review

BACKGROUND

Breast cancer is the most frequent cause of secondary lymphedema. Besides being progressive and chronic, lymphedema is usually hard to treat. That is why the clinicians are more focused on the prevention of its development and progression.

OBJECTIVE

The aim of this study is to evaluate the possible relationship between the age of patients and the severity of breast cancer-related lymphedema (BCRL).

METHODS

PubMed, Scopus, and Ovid MEDLINE databases were searched for articles, which described the relationship between aging and BCRL development. Two authors searched for and selected articles independently.

RESULTS

Out of 562 studies selected, 8 studies met the inclusion criteria. However, 2 papers had the same study population, so only 7 were included in the final analysis. The total number of patients in those 7 studies was 3,904. Five out of 7 studies included in our review depicted the association of more severe forms of BCRL with older age.

CONCLUSION

The final analysis showed that aging is related to the severity of BCRL. However, due to heterogeneity in study outcome reporting, the cause and effect relationship could not be determined.

Lymphatic Senescence: Current Updates and Perspectives

Simple Summary

The lymphatic system is involved in tissue homeostasis, immune processes as well as transport of lipids, proteins and pathogens. Aging affects all physiological systems. However, it is not well studied how aging affects the lymphatic vasculature. Therefore, this review aims at investigating how senescence could lead to changes in the structure and function of the lymphatic vessels. We report that lymphatic senescence is associated with alterations in lymphatic muscles and nerve fibers, lymphatic endothelial cells membrane dysfunction, as well as changes in lymphatic pump, acute inflammation responses and immune function.

Abstract

Lymphatic flow is necessary for maintenance of vital physiological functions in humans and animals. To carry out optimal lymphatic flow, adequate contractile activity of the lymphatic collectors is necessary. Like in all body systems, aging has also an effect on the lymphatic system. However, limited knowledge is available on how aging directly affects the lymphatic system anatomy, physiology and function. We investigated how senescence leads to alterations in morphology and function of the lymphatic vessels. We used the strategy of a review to summarize the scientific literature of studies that have been published in the area of lymphatic senescence. Searches were carried out on PubMed and Web of Science using predefined search queries. We obtained an initial set of 1060 publications. They were filtered to 114 publications based on strict inclusion and exclusion criteria. Finally, the most appropriate 57 studies that specifically addressed lymphatic senescence have been selected for the preparation of this review. Analysis of the literature showed that lymphatic senescence is associated with alterations in lymphatic muscles and nerve fibers, lymphatic glycocalyx function of lymphatic endothelial cells, effects of chronic ultraviolet light exposure and oxidative stress as well as changes in lymphatic pump, acute inflammation responses and immune function. The current review underscores the relevance of the understudied area of lymphatic senescence. Continued research on the impact of aging on the structure and function of the lymphatic vasculature is needed to provide further insights to develop innovative clinical diagnostic—and treatment—modalities as well as to reduce the morbidity associated with diseases related to the lymphatic system.

Sentinel lymph node detection in endometrial cancer with indocyanine green: laparoscopic versus robotic approach

BACKGROUND

The aims of the present study were to assess bilateral sentinel lymph node (SLN) mapping with laparoscopic versus robotic approach, to assess variables affecting bilateral detection rates and to assess survival difference in patients with no/unilateral, compared to bilateral SLN detection.

METHODS

This is a retrospective, single-centre, observational cohort study, including patients with endometrial cancer FIGO stage IA-IVB, treated with minimally invasive primary surgery and undergoing indocyanine green (ICG) injection to detect SLN, between January 2015 and December 2019.

RESULTS

Of the 549 included patients, 286 (52.1%) and 263 (47.9%) underwent the laparoscopic and robotic approach respectively. 387 (70.5%) patients had bilateral SLN mapping, 102 (18.6%) and 60 (10.9%) had unilateral and no mapping, respectively. Patients who underwent the robotic approach were older (median 61 versus 64 years, p=0.046) and had a higher BMI (median 26.0 versus 34.8 kg/m2, p<0.001). No difference in any SLN mapping or in SLN bilateral detection was evident between the laparoscopic or robotic approach (p=0.892 and p=0.507 respectively). Patients with bilateral SLN detection in the entire cohort were younger (p<0.001) and had a better 3-year disease-free survival (DFS) compared to patients with no/unilateral SLN mapping (77.0% versus 66.3%, respectively, p=0.036). No 3-year overall survival (OS) difference was reported (p=0.491).

CONCLUSION

SLN mapping and bilateral SLN detection with ICG in endometrial cancer was not different in the laparoscopic and robotic approach, even though patients undergoing the robotic approach were older and more obese. Bilateral SLN detection was associated with improved 3-year DFS, but not with 3-year OS, compared to no and unilateral SLN detection.

Vascular dysfunction as a potential culprit of sarcopenia

Aging-related changes to biological structures such as cardiovascular and musculoskeletal systems contribute to the development of comorbid conditions including cardiovascular disease and frailty, and ultimately lead to premature death. Although, frail older adults often demonstrate both cardiovascular and musculoskeletal comorbidities, the etiology of sarcopenia, and especially the contribution of cardiovascular aging is unclear. Aging-related vascular calcification is prevalent in older adults and is a known risk factor for cardiovascular disease and death. The effect vascular calcification has on function during aging is not well understood. Emerging findings suggest vascular calcification can impact skeletal muscle perfusion, negatively affecting nutrient and oxygen delivery to skeletal muscle, ultimately accelerating muscle loss and functional decline. The present review summarizes existing evidence on the biological mechanisms linking vascular calcification with sarcopenia during aging.

Lymphatic Capillaries in Aging

The lymphatic system is responsible for fluid drainage from almost every organ in the body. It sustains tissue homeostasis and is also a central part of the immune system. With the discovery of cell-specific markers and transgenic mouse models, it has become possible to gain some insight into the developmental and functional roles of lymphatic endothelial cells (LECs). Only recently, a more direct regulatory role has been assigned to LECs in their functions in immunity responses and chronic diseases. Here, we discuss the changes occurring in aged lymphatic system and the role of lymphatic capillaries in some age-related diseases and experimental animal models.