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.

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.

The Lymphatic System: A Sometimes-Forgotten Compartment in Pharmaceutical Sciences.

The uniqueness of structure and physiology of the lymphatic system make it challenging to delineate all its contributions in the maintenance of our health. However, in the past two decades, the understanding of the importance of the function of this system has evolved and more appreciation has been drawn to the distinctive role it plays in health and disease. The lymphatic system has been linked to the pathophysiology of numerous ailments including cancer, various metabolic diseases, inflammatory conditions, and infections. Moreover, it has also been revealed that lymphatic targeted formulations can enhance the delivery of drugs through the lymphatic system to the bloodstream, bypassing the hepatic first-pass metabolism if taken orally, thus increasing the bioavailability, and improving the pharmacokinetic and toxicological profiles in general. Engineering lymphotropic preparations requires the understanding of many factors, the most important one being that of the physiological environment which they will encounter. Therefore, in this review, we detail the basic structure of the lymphatic system, then highlight the therapeutic and the pharmacokinetic benefits of drug delivery into the lymphatic system. The criteria for drugs and formulations used for lymphotropic delivery are also detailed with a contemporary overview of various studies undertaken in this field.

Tularemia: A rare cause of pediatric lymph nodes adenitis.

Adenopathy in pediatrics can have many different causes: infectious, tumoral, and inflammatory. We report the case of an 8-year-old patient with a febrile popliteal ulceration associated with an inflammatory satellite inguinal lymph node adenitis. Serological tests and polymerase chain reaction analyses confirmed the diagnosis of ulceroglandular tularemia. An appropriate antimicrobial therapy led to a full recovery. This case reminds us to consider tularemia as a potential emergent disease in children presenting with subacute to chronic lymphadenopathy and thereby to choose the correct diagnostic tool and appropriate antimicrobial therapy.

The Post-Acute Phase of SARS-CoV-2 Infection in Two Macaque Species Is Associated with Signs of Ongoing Virus Replication and Pathology in Pulmonary and Extrapulmonary Tissues.

The post-acute phase of SARS-CoV-2 infection was investigated in rhesus (Macaca mulatta) and cynomolgus macaques (Macaca fascicularis). During the acute phase of infection, SARS-CoV-2 was shed via the nose and throat, and viral RNA was occasionally detected in feces. This phase coincided with a transient change in systemic immune activation. Even after the alleged resolution of the infection, computed tomography (CT) and positron emission tomography (PET)-CT revealed pulmonary lesions and activated tracheobronchial lymph nodes in all animals. Post-mortem histological examination of the lung tissue revealed mostly marginal or resolving minimal lesions that were indicative of SARS-CoV-2 infection. Evidence for SARS-CoV-2-induced histopathology was also found in extrapulmonary tissue samples, such as conjunctiva, cervical, and mesenteric lymph nodes. However, 5-6 weeks after SARS-CoV-2 exposure, upon necropsy, viral RNA was still detectable in a wide range of tissue samples in 50% of the macaques and included amongst others the heart, the respiratory tract and surrounding lymph nodes, salivary gland, and conjunctiva. Subgenomic messenger RNA was detected in the lungs and tracheobronchial lymph nodes, indicative of ongoing virus replication during the post-acute phase. These results could be relevant for understanding the long-term consequences of COVID-19 in humans.

Upregulation of VCAM-1 in lymphatic collectors supports dendritic cell entry and rapid migration to lymph nodes in inflammation.

Dendritic cell (DC) migration to draining lymph nodes (dLNs) is a slow process that is believed to begin with DCs approaching and entering into afferent lymphatic capillaries. From capillaries, DCs slowly crawl into lymphatic collectors, where lymph flow induced by collector contraction supports DC detachment and thereafter rapid, passive transport to dLNs. Performing a transcriptomics analysis of dermal endothelial cells, we found that inflammation induces the degradation of the basement membrane (BM) surrounding lymphatic collectors and preferential up-regulation of the DC trafficking molecule VCAM-1 in collectors. In crawl-in experiments performed in ear skin explants, DCs entered collectors in a CCR7- and ß1 integrin-dependent manner. In vivo, loss of ß1-integrins in DCs or of VCAM-1 in lymphatic collectors had the greatest impact on DC migration to dLNs at early time points when migration kinetics favor the accumulation of rapidly migrating collector DCs rather than slower capillary DCs. Taken together, our findings identify collector entry as a critical mechanism enabling rapid DC migration to dLNs in inflammation.

Comparison of different lymph node staging systems in patients with positive lymph nodes in oral squamous cell carcinoma.

OBJECTIVES: The evaluation of neck lymph node metastasis is critical for predicting survival after head and neck cancer treatment. However, traditional pathological N staging does not completely correlate with survival; the total number of lymph nodes resected during surgery affects staging, and a minimal number of nodes must be resected to achieve a superior outcome. Thus, the prognostic abilities of various lymph node staging systems for oral cavity squamous cell carcinoma (OSCC)-positive lymph nodes were compared. MATERIALS AND METHODS: Data for 639 patients with OSCC-positive nodes who were treated and monitored at the Changhua Christian Hospital were retrospectively analyzed. The different N staging systems were compared to evaluate their disease-free survival (DFS) predictability. RESULTS: The areas under the receiver operating characteristic curve were as follows: 0.551 for the traditional American Joint Committee on Cancer (AJCC) N staging, 0.60 for lymph node density (LND), 0.596 for log odds of positive lymph nodes (LODDS), and 0.597 for the number of metastatic lymph nodes (nmLN). The LND, LODDS, and nmLN systems could predict DFS better than AJCC N staging. Multivariable analysis for DFS revealed that extranodal spread, level IV or V positive nodes, and tumor invasion deeper than 13 mm were independent prognostic factors in these four models. LND and LODDS predicted DFS better than pathological N staging. CONCLUSION: LND and LODDS staging predicted DFS better than AJCC N staging for OSCC-positive nodes. In the future, the prognostic ability of AJCC staging may be strengthened by LND or LODDS staging.

Patient-reported outcomes following lymph reconstructive surgery in lower limb lymphedema: A systematic review of literature.

OBJECTIVE: Lymphedema is a chronic, progressive and burdensome disease that is known to have a substantial impact on quality of life (QOL). Hence, the assessment of QOL is an important aspect of any study which seeks to evaluate outcomes after lymph reconstructive surgery. We therefore aimed to analyze currently available patient-reported outcome measurements (PROMS) for patients with lower limb lymphedema (LLL) with regard to their psychometric properties. Furthermore, we intended to evaluate the change in QOL in patient undergoing lymphovenous anastomosis (LVA) or vascularized lymph node transfer (VLNT). METHODS: A literature research of four databases on studies that included PROMS for LLL was conducted. All selected studies were assessed for validity according Consensus-based Standards for the selection of Health Measurement Instruments. Studies that used the Lymph Quality of Life Measure for Limb Lymphedema (LYMQOL) after LVA and/or VLNT were included for quantitative analysis. RESULTS: In total, 988 studies were screened, of which 30 studies were included in this review. We identified six validated PROMS to assess LLL. Of those, the LYMQOL was the most commonly used questionnaire. Based on the LYMQOL, a significant improvement of QOL in LLL was noted in all studies after reconstructive lymph surgery (LVA/VLNT) regardless of lymphedema etiology, stage, or time since diagnosis. On the basis of the Consensus-based Standards for the selection of Health Measurement Instruments criteria, the Lymphoedema Functioning, Disability and Health Questionnaire for Lower Limb Lymphoedema seems to be superior in terms of its psychometric properties. CONCLUSIONS: A significant improvement in the QOL in patients with LLL after reconstructive lymph surgery can be observed. Future studies on reconstructive lymph surgery need to include both objective and congruent volume measurements, as well as data on QOL based a well-validated PROM such as the Lymphoedema Functioning, Disability and Health Questionnaire for Lower Limb Lymphoedema.

Mediastinal Neuroendocrine Carcinoma Slowly Growing for 8 Years after Surgical Resection of Esophageal Squamous Cell Carcinoma.

A 70-year-old woman was referred to our department due to a solitary mediastinal tumor which gradually grew near the site of anastomosis for 8 years after radical surgery of esophageal squamous cell carcinoma. It was difficult to distinguish the lymph node recurrence of esophageal cancer from another tumor of unknown primary origin. Endoscopic ultrasound-guided fine-needle aspiration was performed, and the tumor was diagnosed to be neuroendocrine carcinoma. She received concurrent chemoradiotherapy with etoposide plus cisplatin. After the completion of chemoradiotherapy, the tumor disappeared. A solitary growing tumor which develops after radical resection of cancer would be better to be examined histologically in order to make an accurate diagnosis and select the most appropriate treatment.

Localized Lymph Node Light Chain Amyloidosis.

The prognosis of systemic amyloid light chain (AL) amyloidosis is generally poor, hence requiring chemotherapy or hematopoietic stem cell transplantation, while the prognosis of localized AL amyloidosis without an abnormal monoclonal immunoglobulin light chain is good. Localized AL amyloidosis has been previously reported to be observed in pulmonary, urinary tract, gastrointestinal, oropharyngeal, and laryngeal sites. However, only a few cases of localized lymph node AL amyloidosis have so far been reported. We herein present a case of localized lymph node AL amyloidosis that could possibly be misdiagnosed as systematic AL amyloidosis.

Survival impacts of different nodal characteristics and T-classification in N3 nasopharyngeal carcinoma patients.

OBJECTIVES: We investigated the survival impacts of various nodal characteristics and T-classification on nasopharyngeal carcinoma (NPC) patients with the 8th AJCC/UICC staging criteria N3. MATERIALS AND METHODS: Pretreatment MRIs from 110 staged N3 NPC patients were reviewed. There were 23 T1, 25 T2, 32 T3, and 30 T4, respectively. All except one patient belonged to WHO type II pathology. All patients received curative radiotherapy 68.0-76.8 Gy plus different chemotherapy, including induction, concurrent, adjuvant or any combination. Various endpoints, including OS (overall survival), DFS (disease-free survival), LRFFS (locoregional failure-free survival), DMFFS (distant metastasis failure-free survival) were compared between different nodal characteristics and T-classification. RESULTS: There were no statistically significant differences in all analyzed survival curves between various nodal characteristics, including unilateral N3 vs. bilateral N3, "large" nodes (>6 cm) alone vs. "low" nodes (below the caudal border of cricoid cartilage) alone vs. combined "large" and "low" nodes, risk score 1 vs. 2 vs. 3 vs. 4 (by counting the sum of "large" and "low" nodes in the same case), and radiologic extra-nodal extension. Patients with T4, compared with those of T1-3 have worse OS (5-year rates, 42.2% vs. 82.8%, P < 0.0001), DFS (5-year rates, 43.9% vs. 68.9%, P = 0.0037), LRFFS (5-year rates, 69.3% vs. 82.7%, P = 0.0432), and DMFFS (5-year rates, 57.2% vs. 77.7%, P = 0.0163). CONCLUSIONS: Our results support merging previous N3a and N3b as a N3 category in the 8th edition new staging system. Patients with T4N3 diseases have extremely poor outcome and deserve to strengthen the treatment intensity in future trials.

Prognostic value of log odds of positive lymph nodes in patients with resectable oral squamous cell carcinoma.

OBJECTIVES: Log odds of positive lymph nodes (LODDS) was reported to be significantly associated with prognosis in several malignant tumors. However, few are the studies on the correlation between LODDS and overall survival (OS) in patients with oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: A retrospective study including 233 patients with OSCC during 2009 to 2013 was conducted. We probed the correlation between clinicopathological factor, LODDS, lymph node ratio (LNR), pN and OS. The potential prognostic factor and the independent factor were calculated using univariate analysis and multivariate analysis respectively. The goodness of fit and the discriminability was analyzed with Somer's D value, Nagelkerke R2 index, and Akaike information criterion (AIC). Kaplan-Meier survival curve of OS was contrasted by log-rank test in LODDS, LNR and pN, respectively. RESULTS: According to the X-tile, the cut-off values are -1.491 and -0.763 for LODDS, 0.024 and 0.133 for LNR. LODDS, LNR and pN were significantly correlated with OS by univariate analysis (P < 0.001). Multivariate analysis demonstrated LODDS, LNR and pN as an independent prognostic factors for OS (P < 0.01). Compared with pN and LNR models, LODDS showed the strongest predictive power. LODDS was superior to LNR and pN in predicting outcomes in patients with no positive lymph nodes and inadequate neck dissection. CONCLUSION: LODDS would be incorporated into future N classification, which may be conducive to discern the prognosis of OSCC and make a decision of adjuvant therapy in clinical practice.

Meningeal lymphatics clear erythrocytes that arise from subarachnoid hemorrhage.

Extravasated erythrocytes in cerebrospinal fluid (CSF) critically contribute to the pathogenesis of subarachnoid hemorrhage (SAH). Meningeal lymphatics have been reported to drain macromolecules and immune cells from CSF into cervical lymph nodes (CLNs). However, whether meningeal lymphatics are involved in clearing extravasated erythrocytes in CSF after SAH remains unclear. Here we show that a markedly higher number of erythrocytes are accumulated in the lymphatics of CLNs and meningeal lymphatics after SAH. When the meningeal lymphatics are depleted in a mouse model of SAH, the degree of erythrocyte aggregation in CLNs is significantly lower, while the associated neuroinflammation and the neurologic deficits are dramatically exacerbated. In addition, during SAH lymph flow is increased but without significant lymphangiogenesis and lymphangiectasia. Taken together, this work demonstrates that the meningeal lymphatics drain extravasated erythrocytes from CSF into CLNs after SAH, while suggesting that modulating this draining may offer therapeutic approaches to alleviate SAH severity.

Lymph node harvesting in gastric cancer: the crucial role of t stage.

PURPOSE: Nodal status represents probably the most important determinant of gastric cancer prognosis. The purpose of the present study was to assess the impact of the primary tumor's T stage on lymph node harvesting after D1 resections for gastric cancer. METHODS: Between January 2000 and January 2012, the medical files of patients who presented to our department with the diagnosis of gastric cancer and were submitted to a gastric resection with curative intent were retrospectively reviewed. A total of 134 gastric cancer patients (mean age 67.36±9.64 - 35 females and 99 males) were submitted to a gastrectomy in our department (total or subtotal) with curative intent. The distribution of the tumors within the stomach was as follows: upper third - 37 patients, middle third - 49 patients and lower third - 46 patients. RESULTS: Lymph node retrieval was superior in advanced T stage patients (T3,T4a/T4b) compared to their low T stage (T1a/T1b,T2) counterparts (p=0.0008). Similar findings were encountered when the comparison was reduced to the subtotal gastrectomy subgroup (p=0.0047). However, although there was a distinct trend, statistical significance was not reached for the patient group submitted to total gastrectomy (p=0.1088). CONCLUSION: The results of the present study seem to add another value i.e. tumor's T stage in the equation of lymph node retrieval in gastric cancer resection specimens. Lymph node retrieval in gastric cancer patients appeared to be dependent to the primary tumors T stage in the given patient sample.

Higher immune response induced by vaccination in Houhai acupoint relates to the lymphatic drainage of the injection site.

Houhai acupoint (HA) is a site for acupuncture stimulation, located in the fossa between the anus and tail base in animals. To evaluate HA as a potential immunization site, the immune responses were compared when HA and the conventional site nape were vaccinated in rats. The results showed that injection of a porcine epidemic diarrhea virus (PEDV) vaccine in HA induced significantly higher IgG, IgG1, IgG2, splenocyte proliferation and mRNA expression of IL-2, IL-4 and IFN-γ than in the nape. To search for the underlying mechanisms, the draining lymph nodes for HA and the nape were investigated. When rats were injected in HA with Indian ink, 11 lymph nodes including caudal mesenteric lymph node and bilateral gluteal lymph nodes, posterior inguinal lymph nodes, lumbar lymph nodes, internal iliac lymph nodes and popliteal lymph nodes were visibly stained with the ink and injection of a model antigen ovalbumin (OVA) in HA resulted in detection of OVA by western blotting while in the same lymph nodes only a pair of lymph nodes (central brachial lymph nodes) were observed when Indian ink or OVA was injected in the nape. IL-2 mRNA expression was detected in all the lymph nodes when PEDV vaccine was injected. Therefore, the enhanced immune response elicited by vaccination in HA may be attributed to more lymphocytes activated.

Application of computed tomography, positron emission tomography-computed tomography, magnetic resonance imaging, endobronchial ultrasound, and mediastinoscopy in the diagnosis of mediastinal lymph node staging of non-small-cell lung cancer: A protocol for a systematic review.

BACKGROUND: Ruling out distant metastases, non-small cell lung cancer (NSCLC)treatment depends on the results of mediastinal node staging (N staging). Several diagnostic methods play central roles in mediastinal N staging. This study is intended to evaluate the existing diagnostic methods and report quality, and to search for the best method for staging mediastinal lymph nodes. METHODS: We searched PubMed, Embase, and the Cochrane Library to identify relevant studies, including randomized controlled trials and retrospective studies. These studies report the application of computed tomography, positron emission tomography-computed tomography, magnetic resonance imaging, endobronchial ultrasound, and mediastinoscopy in the diagnosis of mediastinal lymph node staging of NSCLC. The quality of the literature was assessed using the Quality Assessment of Diagnostic Accuracy Study 2. The true positive, false positive, true negative, and false negative of each study was extracted. The corresponding sensitivity, specificity, and other indicators were calculated and the Summary Receiver Operating curve was established. Then, head-to-head and indirect comparison meta-analyses will be conducted. RESULTS: The results of this study will be published in a peer-reviewed journal. CONCLUSION: This study will provide basis for mediastinal lymph node staging of non-small cell lung cancer. PROSPERO REGISTRATION NUMBER: CRD42019145667.

[Analysis of lymphatic drainage pathways using infrared fluorescence in patients with lung cancer]. / Izuchenie putei regionarnogo limfoottoka pri rake legkogo s pomoshch'iu infrakrasnoi fluorestsentsii.

OBJECTIVE: To develop a method for analysis of lymphatic drainage pathways from the lobe of the lung affected by non-small cell lung cancer (NSCLC) using infrared fluorescence. MATERIAL AND METHODS: A study enrolled patients with NSCLC who underwent anatomic resection of the lung with systematic lymph node dissection and preliminary intraoperative peritumoral injection of indocyanine green conjugate with human albumin. Registration of fluorescence in regional lymph nodes (LN) was carried out immediately after excision of specimen using the FLUM-808 instrumental system. RESULTS: Infrared fluorescence was observed in 117 hilar and mediastinal lymph nodes from 43 patients (2.7 nodes per a patient). Comparison of localization of fluorescent LN with localization of tumor in various lobes established significant variability of lymphatic drainage pathways. CONCLUSION: The developed method of infrared fluorescent evaluation of lymphatic drainage in patients with NSCLC confirms the necessity of systematic lymph node dissection for adequate staging.

Ischemia and reperfusion injury in superficial inferior epigastric artery-based vascularized lymph node flaps.

Vascularized lymph node transfer (VLNT) is a promising treatment modality for lymphedema; however, how lymphatic tissue responds to ischemia has not been well defined. This study investigates the cellular changes that occur in lymph nodes in response to ischemia and reperfusion. Lymph node containing superficial epigastric artery-based groin flaps were isolated in Prox-1 EGFP rats which permits real time identification of lymphatic tissue by green fluorescence during flap dissection. Flaps were subjected to ischemia for either 1, 2, 4, or 8 hours, by temporarily occluding the vascular pedicle. Flaps were harvested after 0 hours, 24 hours, or 5 days of reperfusion. Using EGFP signal guidance, lymph nodes were isolated from the flaps and tissue morphology, cell apoptosis, and inflammatory cytokines were quantified and analyzed via histology, immunostaining, and rtPCR. There was a significant increase in collagen deposition and tissue fibrosis in lymph nodes after 4 and 8 hours of ischemia compared to 1 and 2 hours, as assessed by picrosirius red staining. Cell apoptosis significantly increased after 4 hours of ischemia in all harvest times. In tissue subject to 4 hours of ischemia, longer reperfusion periods were associated with increased rates of CD3+ and CD45+ cell apoptosis. rtPCR analysis demonstrated significantly increased expression of CXCL1/GRO-α with 2 hours of ischemia and increased PECAM-1 and TNF-α expression with 1 hour of ischemia. Significant cell death and changes in tissue morphology do not occur until after 4 hours of ischemia; however, analysis of inflammatory biomarkers suggests that ischemia reperfusion injury can occur with as little as 2 hours of ischemia.

Vasomotor influences on glymphatic-lymphatic coupling and solute trafficking in the central nervous system.

Despite the recent description of meningeal lymphatic vessels draining solutes from the brain interstitium and cerebrospinal fluid (CSF), the physiological factors governing cranial lymphatic efflux remain largely unexplored. In agreement with recent findings, cervical lymphatic drainage of 70 kD and 2000 kD fluorescent tracers injected into the adult mouse cortex was significantly impaired in the anesthetized compared to waking animals (tracer distribution across 2.1 ± 4.5% and 23.7 ± 15.8% of deep cervical lymph nodes, respectively); however, free-breathing anesthetized mice were markedly hypercapnic and acidemic (paCO2 = 64 ± 8 mmHg; pH = 7.22 ± 0.05). Mechanical ventilation normalized arterial blood gases in anesthetized animals, and rescued lymphatic efflux of interstitial solutes in anesthetized mice. Experimental hypercapnia blocked cervical lymphatic efflux of intraparenchymal tracers. When tracers were injected into the subarachnoid CSF compartment, glymphatic influx into brain tissue was virtually abolished by hypercapnia, while lymphatic drainage was not appreciably altered. These findings demonstrate that cervical lymphatic drainage of interstitial solutes is, in part, regulated by upstream changes in glymphatic CSF-interstitial fluid exchange. Further, they suggest that maintaining physiological blood gas values in studies of glymphatic exchange and meningeal lymphatic drainage may be critical to defining the physiological regulation of these processes.