Lymphatic Channels Research Articles

Conservative management of chylous leak after open radical nephrectomy in an adult patient: a case report and literature review

BackgroundChylous ascites is rare but still a recognized complication of retroperitoneal surgeries caused mostly by inadvertent trauma to lymphatic channels. In this article, we present a case report and literature review of adult patient, with malignant tumor of upper urinary tract, who developed chylous leak after open nephrectomy.Case presentationWe present a case of chylous leak for a 67-year-old female patient, presented to urology clinic with complaining of left loin pain and gross hematuria, found to have upper urinary tract tumor, she underwent open radical nephrectomy with lymph nodes dissection, and postoperatively she had chylous leak that is treated conservatively using octreotide and spironolactone without the need for total parenteral nutrition.ConclusionConservative management should always be the first choice of management of chylous leak and chylous ascites. Careful anatomical identification and securing of the periaortic lymphatics are needed to decrease the risk of postoperative chylous leak and ascites.

Lymphangioma Circumscriptum of the Vulva- A Case Series

Vulval dermatoses pose a diagnostic and therapeutic challenge for the dermatologists. Lymphangioma Circumscriptum (LC) is a form of lymphangioma affecting the skin and subcutaneous tissues that is characterised by benign dilation of lymphatic channels. This uncommon condition is known to occur over the chest, mouth, axilla, tongue, and rarely in the vulva. In this series, authors present three cases of LC of vulva in women between the age group of 45 to 60 years with late-onset fluid-filled lesions over the vulva. The first case had history of hysterectomy prior to onset of lesions, the second case had a spontaneous onset of lesions while the third was a suspected case of pelvic tuberculosis with secondary lymphangioma.

A review on lymphoedema – causes, confusions and complications

Lymphoedema is a chronic, progressive debilitating disorder of lymphoreticular system, characterized by abnormal collection of excessive proteins, oedema, chronic inflammation and fibrosis.Primary lymphoedema, associated with underlying, but inherent malfunction of lymphatic channels, unilateral or bilateral. It can be further subdivided in to congenital lymphoedema, lymphoedema praecox and lymphoedema tarda. Depends on the age of onset or manifestation. Another genetic disorder of lymphatic dysfunction is Milroy disease. It is an autosomal dominant condition due to VEGFR3 mutation characterised by lymphatic hypoplasia. Secondary lymphoedemas are more frequent than primary to dysfunction of lymphatics. Mostly localised, follwing recurrent infections, trauma, surgery, obesity and malignancy.Inadequate drainage of lymphatics, leads to accumulation of lymph, interstitial fluid and proteins in skin and subcutaneous tissue. Elastic tissue disruption, fibroblast stimulation occurs and the resulting hypoxia causes chronic inflammation and fibrosis. Later adipocyte remodelling occurs and proinflammatory cytokines secreted.Starts as pitting non tender pedal oedema, later skin thickening and fibrosis which results in non-pitting oedema. Squared off appearance and Kaposi Stemmer sign are characteristic features. May develop lymphorrhoea and secondary infections may supervene. Chronic venous insufficiency, lipoedema, myxedema.Vicious cycle of infections and lymphedema.Lymphoscintigraphy, lymphoflouroscopy- gold standard.Depends on severity. Pneumatic compression garments, Low level light therapy (LLLT), Extracorporeal shock wave therapy (ESWT). Advanced stages may require surgical debulking, lymphatic reconstruction. But the results are mostly unsatisfactory, recurrences are inevitable. Combined multi-disciplinary approaches will be helpful and that should be continued throughout their life.

Anatomical Features of the Deep Cervical Lymphatic System and Intrajugular Lymphatic Vessels in Humans.

Background: Studies in rodents have re-kindled interest in the study of lymphatics in the central nervous system. Animal studies have demonstrated that there is a connection between the subarachnoid space and deep cervical lymph nodes (DCLNs) through dural lymphatic vessels located in the skull base and the parasagittal area. Objective: To describe the connection of the DCLNs and lymphatic tributaries with the intracranial space through the jugular foramen, and to address the anatomical features and variations of the DCLNs and associated lymphatic channels in the neck. Methods: Twelve formalin-fixed human head and neck specimens were studied. Samples from the dura of the wall of the jugular foramen were obtained from two fresh human cadavers during rapid autopsy. The samples were immunostained with podoplanin and CD45 to highlight lymphatic channels and immune cells, respectively. Results: The mean number of nodes for DCLNs was 6.91 ± 0.58 on both sides. The mean node length was 10.1 ± 5.13 mm, the mean width was 7.03 ± 1.9 mm, and the mean thickness was 4 ± 1.04 mm. Immunohistochemical staining from rapid autopsy samples demonstrated that lymphatic vessels pass from the intracranial compartment into the neck through the meninges at the jugular foramen, through tributaries that can be called intrajugular lymphatic vessels. Conclusions: The anatomical features of the DCLNs and their connections with intracranial lymphatic structures through the jugular foramen represent an important possible route for the spread of cancers to and from the central nervous system; therefore, it is essential to have an in-depth understanding of the anatomy of these lymphatic structures and their variations.

SWELLING OF THE SUBCUTANEOUS INTERSTITIUM UNDER THE INFLUENCE OF ISONIAZID AND DIFFERENT PH LEVELS

The article deals with the issues of interstitial conductivity for isoniazid and saline solution with different pH levels. Experimental studies were conducted to substantiate and explain the mechanisms of effectiveness of indirect endolymphatic drug administration. At the present stage, lymphotropic administration of anti-tuberculosis drugs occupies a worthy place in the complex therapy of patients with pulmonary and extrapulmonary tuberculosis. Lymphotropic therapy is an etio-pathogenetic method of treating patients and consists of regional subcutaneous injections of medicinal solutions with the use of lymphotropy factors, among which it is important to create an active functioning of the interstitial zones of lymphotropic administration, which determines the flow of drugs into the lymphatic channel. The influence of acidification and alkalinization of the medium on the hydrophilicity of the interstitium of the subcutaneous tissue of the parasternal zone, armpit, and interdigital spaces was studied. As incubation solutions, saline solution with pH 6.9, pH 7.4, pH 6.0 and 10% isoniazid solution (10%H) were used. It was found that the interstitial subcutaneous tissue of the lymphotropic injection zones is characterized by different intensity of swelling, which is probably due to the morphological features of the fiber, different content of loose connective and adipose tissues in it. The swelling coefficient is regulated by the pH level of incubation solutions and the chemical structure of the administered lymphotropically medicinal substance. Features of interaction between interstitial lymphotropic points and the drug should be taken into account when prescribing indirect endolymphatic therapy schemes. It is likely that the pH of the administered solutions must be maintained at the level of the physiological norm (7.4). Isoniazid in the lymphotropic points creates a depot that is more pronounced in the parasternal region.

Prophylactic central neck dissection has no advantage in patients with metastatic papillary thyroid cancer to the lateral neck.

Papillary thyroid cancer (PTC) usually metastasizes via lymphatic channels in a sequential fashion, first to the central compartment, followed by the lateral neck. PTC patients diagnosed with lateral neck disease (N1b) without proof for central involvement traditionally undergo prophylactic central neck dissection (pCND). However, substantial evidence on outcomes to support this approach is lacking. We conducted a dual center retrospective study to compare the rate of central neck recurrence between N1b PTC patients undergoing pCND and those spared pCND. All patients diagnosed with N1b PTC who underwent total thyroidectomy and lateral neck dissections with or without pCND between January 1998 and December 2015 were included in this study. The rates of central neck recurrences were compared between the groups. The 111 patients who met the inclusion criteria were 44 females (39.6%) and 67 males (60.4%), with a mean age of 50.2 ± 17.7 years, and a mean follow-up of 10.2 ± 5.3 years. Sixty patients (54.1%) underwent a pCND and 51 patients (45.9%) did not (non-pCND). During follow-up, 18 patients (16.2%) had level VI recurrences, 13 in the pCND group and 5 in the non-pCND group. Cox-regression models with propensity scoring did not reveal any inclination or an advantage for performing pCND. The present study demonstrated no advantage in performing pCND to prevent central neck recurrence among PTC patients with lateral neck involvement only. These findings question the need for pCND in patients without clinical evidence of central neck disease.

The value of virtual bronchoscopic navigation and radial endobronchial ultrasound-guided transbronchial lung cryobiopsies for pulmonary lymphangitic carcinomatosis.

BackgroundPulmonary lymphangitic carcinomatosis (PLC) is characterized by malignant infiltration into lung lymphatic channels from a primary site and is often observed in advanced malignant tumors. This study aimed to evaluate the diagnostic yield of transbronchial lung cryobiopsy in PLC guided by radial endobronchial ultrasound and virtual bronchoscopic navigation (VBN).MethodsThis prospective study enrolled 40 patients with clinical and radiologic features indicating PLC. The radial endobronchial ultrasound probe was initially advanced to the region of interest of the desired lobe near the pleura with guidance by VBN. Transbronchial lung biopsy and transbronchial lung cryobiopsy were both performed in the same ROI of all patients with the obtained samples being sent to the pathology laboratory for diagnostic analysis. Procedural complications were recorded.ResultsThe average number of transbronchial lung biopsy and transbronchial lung cryobiopsy specimens were 4 (3 to 6) and 2 (1 to 3), respectively (t=10.43, P<0.01), with the corresponding mean diameters per biopsy being 3.7 and 8.7 mm (t=12.37, P<0.01). The diagnostic yields of transbronchial lung biopsy and transbronchial lung cryobiopsy were 70% (28/40) and 92.5% (37/40), respectively. The final positive predictive values of transbronchial lung cryobiopsy and transbronchial lung biopsy for PLC were 94.4% (34/36) and 77.8% (28/36), respectively (χ2=23.94, P<0.01). Further, 52.2% (12/23) and 81.5% (22/27) of the patients in the transbronchial lung biopsy and transbronchial lung cryobiopsy groups, respectively, were diagnosed with non-small lung cancer after further molecular analysis (χ2=19.56, P<0.01). Only 2 (5%) cases presented postoperative pneumothorax. Moreover, 0 (0%), 3 (7.5%), and 17 (42.5%) patients presented severe, moderate, and mild bleeding, respectively. There were no other adverse events or deaths.ConclusionsTransbronchial lung cryobiopsy with the guidance of radial endobronchial ultrasound and VBN without fluoroscopy has a good diagnostic yield for PLC; moreover, it allows one to obtain adequate and intact tissue samples for further molecular analysis.

Imaging of fetal lymphangiectasias: prenatal and postnatal imaging findings.

Lymphangiectasias are lymphatic malformations characterized by the abnormal dilation and morphology of the lymphatic channels. The classification and treatment of these disorders can be challenging given the limited amount of literature available in children. Various imaging modalities are used to confirm suspected diagnosis, plan the most appropriate treatment, and estimate a prognosis. Prenatal evaluation is performed using both prenatal US imaging and fetal MRI. These modalities are paramount for appropriate parental counseling and planning of perinatal care. During the neonatal period, chest US imaging is a useful modality to evaluate pulmonary lymphangiectasia because other modalities such as conventional radiography and CT display nonspecific findings. Finally, the recent breakthroughs in lymphatic imaging with MRI have allowed us to better classify lymphatic disorders. Dynamic contrast-enhanced lymphangiography, conventional lymphangiography and percutaneous lymphatic procedures offer static and dynamic evaluation of the central conducting lymphatics in children, with excellent spatial resolution and the possibility to provide treatment. The purpose of this review is to discuss the normal and abnormal development of the fetal lymphatic system and how to best depict it by imaging during the prenatal and postnatal life.

Morphogenesis lymph node of domestic pig

The visceral and somatic lymph nodes of a pig of domestic 1-120 day old were examined. Found that the lymph nodes have a common connective tissue capsule and different levels of fusion of individual subunits. In the center of each subunit, the capsule forms invaginations of the capsular trabecula, dividing the parenchyma of each structural unit into «Ʊ»-shaped structures, fused with lateral and lower parts. The number and degree of fusion of subunits is different and depends on the age of the animals and the location of the lymph node. The greatest degree of fusion of individual units of the lymph node was found in the superficial cervical and axillary I ribs. In the mandibular, superficial parotid and superficial inguinal lymph nodes, the segments are clearly contoured already in newborn piglets. Segments are predominantly bean-spherical in shape with a wide base. The fusion of the segments occurs in their central part, and on the surface the gates of the subunits are clearly contoured in the form of numerous depressions. In the visceral lymph nodes, the portal and splenic lymph nodes have the smallest segmentation, and the gastric, tracheobronchial, and iliocolic lymph nodes are the largest. The number of segments varies from two in newborn piglets to five in 120-day-old pigs. The variability of the morphometric parameters of the lymph nodes of a domestic pig is due to a different number of afferent lymphatic vessels, and, accordingly, to different scales of the lymphatic basins. Thus, the lymph nodes of the domestic pig are complexes of subunits fused to varying degrees. Somatic lymph nodes are highly segmented. The degree of consolidation of subunits in the visceral lymph nodes is less pronounced. Linear measurements of organs vary depending on the age of the animals, gradually increasing up to 120 days with a tendency for these indicators to prevail in the somatic lymph nodes. Key words: domestic pig, lymph node, subunit, topography, morphometry

Lower Extremity Lymphatic Function in Nonambulatory Patients with Neuromuscular Disease.

Background: Lymphedema results from inadequate lymphatic function causing swelling in subcutaneous tissues. Lymph is transported proximally through valved lymphatic channels and muscle contraction. The purpose of this study was to determine lymphatic function in nonambulatory patients with lower extremity neuromuscular disease. Methods and Results: Our Lymphedema Program database of 700 patients was reviewed for nonambulatory patients with lower extremity neuromuscular disease. Patient age, gender, disease, body mass index (BMI), and lymphoscintigram result were recorded. Eight patients were included in the study: myelomeningocele (n = 6), spinal muscle atrophy type 2 (n = 1), Charcot Marie Tooth (n = 1). Patient ages were between 15 and 36 years; five were female. BMI range for patients without swelling or a normal lymphoscintigram (n = 4) was 22-27. Four subjects with lymphatic dysfunction by lymphoscintigram all were obese (BMI 36-74; p = 0.03). Conclusions: Nonambulatory patients with lower extremity neuromuscular dysfunction and swelling can exhibit normal lymphatic function. Obesity is associated with abnormal lymphoscintigram result and lymphedema in this patient population. Individuals should be advised to maintain a normal BMI.

Percutaneous afferent lymphatic vessel sclerotherapy for postoperative lymphatic leakage after previous ineffective therapeutic transpedal lymphangiography

BackgroundTo demonstrate the efficacy of percutaneous computed tomography (CT)-guided afferent lymphatic vessel sclerotherapy (ALVS) in the treatment of postoperative lymphatic leakage (LL) after ineffective therapeutic transpedal lymphangiography (TL).MethodsA retrospective review in this institute involving 201 patients was conducted from May 2011 to September 2018. Patients diagnosed with postoperative LL undergoing ineffective therapeutical TL before the performance of percutaneous CT-guided ALVS were involved. Technical success and clinical success of TL and ALVS were established. The technical success and efficacy of ALVS in the treatment of postoperative LL after ineffective therapeutic TL were assessed. The clinical success rate of ALVS is also assessed, and the complications are reviewed.ResultsIn total, nine patients were involved including three patients (33.3%) presented with chylothorax, three patients (33.3%) presented with inguinal lymphatic fistula/lymphocele, and three patients (33.3%) presented with lymphatic fistula in the thigh; 27 ± 18 days (mean ± standard deviation) after surgery, therapeutic TL was successfully performed and showed definite afferent lymphatic vessel and leakage site in all the patients. Due to clinical failure after TLs, the following ALVS was performed with a mean interval of 12 ± 8 days after TL. The technical success rate was 9/9 (100.0%, 95% confidence interval [CI] 63.1–100.0%). An average of 2.7 ± 1.3 mL 95% ethanol as sclerosant agent was injected during the procedure. The clinical success was observed in 8 of the 9 patients (88.9%, 95% CI 51.8–99.7%) with a time between ALVS and the LL cure of 8 ± 6 days. No complications were reported.ConclusionsOur results showed the role of percutaneous CT-guided ALVS as a safe, feasible, and effective salvage treatment for postoperative LL after ineffective TL.

Lymph Node Subcapsular Sinus Microenvironment-On-A-ChipModeling Shear Flow Relevant to Lymphatic Metastasis and Immune Cell Homing.

SummaryA lymph node sinus-on-a-chip adhesion microfluidic platform that recapitulates the hydrodynamic microenvironment of the lymph node subcapsular sinus was engineered. This device was used to interrogate the effects of lymph node remodeling on cellular adhesion in fluid flow relevant to lymphatic metastasis. Wall shear stress levels analytically estimated and modeled after quiescent and diseased/inflamed lymph nodes were experimentally recapitulated using a flow-based microfluidic perfusion system to assess the effects of physiological flow fields on human metastatic cancer cell adhesion. Results suggest that both altered fluid flow profiles and presentation of adhesive ligands, which are predicted to manifest within the lymph node subcapsular sinus as a result of inflammation-induced remodeling, and the presence of lymph-borne monocytic cells may synergistically contribute to the dynamic extent of cell adhesion in flow relevant to lymph node invasion by cancer and monocytic immune cells during lymphatic metastasis.

Inferior epigastric artery lymph nodes: A pathway for systemic dissemination from peritoneal carcinomatosis?

We report, for the first time in the literature, a metastatic lymphatic pathway along the inferior epigastric vessels, through the inferior epigastric lymph nodes (IELNs), in patients with peritoneal carcinomatosis (PC). Interestingly, these lymph nodes (LNs) in the anterior retroperitoneum were not detectable on preoperative imaging. They may, however, represent a pertinent systemic dissemination pathway for PC. In patients undergoing indocyanine green-fluorescence imaging during cytoreductive surgery for PC, an incidental finding of a hyperfluorescent LN, harboring metastatic tumorous cells, around the inferior epigastric artery was made. In three out of fivepatients with clear fluorescent hotspot, the harvested LNwas harboring metastatic cancerous cells. None of these nodes, whether negative or positive, was visible on any preoperative imaging modalities. A protocol to sample, in a systematic manner, the IELN in patients with PC, is currently being devised at our institution. These lymphatic nodes basin and channels might reveal to be a potential passage from peritoneal metastasis to the extraperitoneal lymphatic compartment, representing an independent pathway for cancerous cell dissemination. This will bring us to further investigate the prevalence and the prognostic significance of these LNs.

Noninvasive Characterization of Human Glymphatics and Meningeal Lymphatics in an in vivo Model of Blood–Brain Barrier Leakage

To evaluate human glymphatics and meningeal lymphatics noninvasively. This prospective study implemented 3-dimensional (3D) isotropic contrast-enhanced T2 fluid-attenuated inversion recovery (CE-T2-FLAIR) imaging with a 3T magnetic resonance machine to study cerebral glymphatics and meningeal lymphatics in patients with reversible cerebral vasoconstriction syndrome (RCVS) with (n = 92) or without (n = 90) blood-brain barrier (BBB) disruption and a diseased control group with cluster headache (n = 35). The contrast agent gadobutrol (0.2mmol/kg [0.2ml/kg]) was administered intravenously in all study subjects. In total, 217 patients (182 RCVS, 35 cluster headache) were analyzed and separated into 2 groups based on the presence or absence of visible gadolinium (Gd) leakage. Para-arterial tracer enrichment was clearly depicted in those with overt BBB disruption, while paravenous and parasinus meningeal contrast enrichment was evident in both groups. Paravenous and parasinus contrast enrichment remained in RCVS patients in the remission stage and in cluster headache patients, suggesting that these meningeal lymphatic channels were universal anatomical structures rather than being phase- or condition-specific. Additionally, we demonstrated nodular leptomeningeal enhancement in 32.3% of participants, which might represent potential lymphatic reservoirs. Four selected RCVS patients who received consecutive contrasted 3D isotropic FLAIR imaging after gadobutrol administration showed that the Gd persisted for at least 54 minutes and was completely cleared within 18 hours. This large-scale in vivo study successfully demonstrated the putative human para-arterial glymphatic transports and meningeal lymphatics by clear depiction of para-arterial, parasinus, and paravenous meningeal contrast enrichment using high-resolution 3D isotropic CE-T2-FLAIR imaging noninvasively; this technique may serve as a basis for further studies to delineate clinical relevance of glymphatic clearance. ANN NEUROL 2021;89:111-124.

Morphogenesis of limph nodes in Muscovy ducks during early posnatal onthogenesis

The dynamics of mass and linear parameters of lymph nodes of ducks is a direct reflection of structural and functional transformations of their lymphatic parenchyma. The peculiarities of quantitative dynamics of tissue components of peripheral lymphatic organs at early stages of postnatal ontogenesis are to a great extent determined by advanced growth rates of their absolute mass against the background of sharp increase of their antigenic stimulation intensity. Parenchyma of lymph nodes of newborn ducklings is characterized by relatively low degree of differentiation and is represented by diffuse lymphatic tissue with no pronounced signs of its division into separate functional zones. Internally, the lymphatic channel is represented by only two lymphatic sinuses - the central one, which is located in the central part of the organ and occupies a large relative area and a discrete edge sinus, which borders on the node capsule and has a much smaller relative area and, accordingly, is located at its periphery. The organ parenchyma is a diffuse cluster of stromal and lymphatic cells in the enlarged lymphatic vessel between the central (inner) and edge (outer) lymphatic sinuses, without signs of its division into cortical and brain matter. Among the lymphatic tissue of the lymph node, reticular stroma cells and the population of small lymphocytes have the largest relative amount.

Ovarian Cystic Lymphangioma: A Rare Case Report with Review of Literature

Lymphangiomas of the ovary are unusual benign tumours characterised by proliferation of lymphatic channels, composed of cystic spaces lined by a single layer of endothelial cells. We present a case of 61-year-old woman who presented with complaints of pain abdomen. Investigations revealed a large left ovarian multiseptate multiloculated cystic mass extending to pelvis, abdominal cavity and infraumbilical region likely neoplastic. Total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed suspecting malignancy. Histopathological examination revealed an ovarian lymphangioma.

Lymph Liquid Biopsy for Detection of Cancer Stem Cells.

Collection of a blood sample defined by the term "blood liquid biopsy" is commonly used to detect diagnostic, prognostic, and therapeutic decision-making markers of metastatic tumors including circulating tumor cells (CTCs). Many tumors also release CTCs and other markers into lymph fluid, but the utility of lymphatic markers largely remains unexplored. Here, we introduce lymph liquid biopsy through collection of peripheral (afferent) and central (thoracic duct [TD]) lymph samples and demonstrates its feasibility for detection of stem-like CTCs potentially responsible for metastasis development and tumor relapse. Stemness of lymphatic CTCs (L-CTCs) was determined by spheroid-forming assay in vitro. Simultaneously, we tested blood CTCs by conventional blood liquid biopsy, and monitored the primary tumor size, early metastasis in a sentinel lymph node (SLN) and distant metastasis in lungs. Using a mouse model at early melanoma stage with no distant metastasis, we identified stem-like L-CTCs in lymph samples from afferent lymphatic vessels. Since these vessels transport cells from the primary tumor to SLN, our finding emphasizes the significance of the lymphatic pathway in development of SLN metastasis. Surprisingly, in pre-metastatic disease, stem-like L-CTCs were detected in lymph samples from the TD, which directly empties lymph into blood circulation. This suggests a new contribution of the lymphatic system to initiation of distant metastasis. Integration of lymph and blood liquid biopsies demonstrated that all mice with early melanoma had stem-like CTCs in at least one of three samples (afferent lymph, TD lymph, and blood). At the stage of distant metastasis, spheroid-forming L-CTCs were detected in TD lymph, but not in afferent lymph. Altogether, our results demonstrated that lymph liquid biopsy and testing L-CTCs holds promise for diagnosis and prognosis of early metastasis. © 2020 International Society for Advancement of Cytometry.

Extracellular bacterial lymphatic metastasis drives Streptococcus pyogenes systemic infection

Unassisted metastasis through the lymphatic system is a mechanism of dissemination thus far ascribed only to cancer cells. Here, we report that Streptococcus pyogenes also hijack lymphatic vessels to escape a local infection site, transiting through sequential lymph nodes and efferent lymphatic vessels to enter the bloodstream. Contrasting with previously reported mechanisms of intracellular pathogen carriage by phagocytes, we show S. pyogenes remain extracellular during transit, first in afferent and then efferent lymphatics that carry the bacteria through successive draining lymph nodes. We identify streptococcal virulence mechanisms important for bacterial lymphatic dissemination and show that metastatic streptococci within infected lymph nodes resist and subvert clearance by phagocytes, enabling replication that can seed intense bloodstream infection. The findings establish the lymphatic system as both a survival niche and conduit to the bloodstream for S. pyogenes, explaining the phenomenon of occult bacteraemia. This work provides new perspectives in streptococcal pathogenesis with implications for immunity.

Morphological hallmarks facilitating distinction of omental milky spots and lymph nodes: an exploratory study on their discriminative capacity.

Omental milky spots (OMSs) are the primary lymphoid structures of the greater omentum. However, the presence of lymph nodes (LNs) has occasionally been mentioned as well. Understanding which lymphoid structures are present is of significance, especially in gastric tumor metastasis; tumor deposits in omental LNs suggest local lymphatic spread, whereas tumor deposits in OMSs suggest peritoneal spread and hence extensive disease. Since LNs and OMSs share morphological characteristics and OMSs might be wrongly identified as LNs, reliable hallmarks facilitating easy discrimination are needed. A series of microscopic morphological hallmarks unique to LNs were selected as potential candidates and were assessed for their discriminative capacity: 1) capsule, 2) trabeculae, 3) subcapsular sinus, 4) afferent lymphatic vessels, 5) distinct B- and T cell regions, and 6) a layered organization with, from the outside in a capsule, cortex, paracortex, and medulla. These hallmarks were visualized by multiple staining techniques. Hallmarks 1, 2 5 and 6 were shown to be the most efficient as these were consistent and discriminative. They were best visualized by Picrosirius red, smooth muscle actin and a B-cell / T-cell double staining. The presence of a capsule, trabeculae, distinct B- and T-cell regions and a layered organization represent consistent and reliable morphological features which allow to easily distinguish LNs from OMSs, especially when applied in combination.

Regulation of lymphatic function and injury by nitrosative stress in obese mice

ObjectiveObesity results in lymphatic dysfunction, but the cellular mechanisms that mediate this effect remain largely unknown. Previous studies in obese mice have shown that inducible nitric oxide synthase-expressing (iNOS+) inflammatory cells accumulate around lymphatic vessels. In the current study, we therefore tested the hypothesis that increased expression of iNOS results in nitrosative stress and injury to the lymphatic endothelial cells (LECs). In addition, we tested the hypothesis that lymphatic injury, independent of obesity, can modulate glucose and lipid metabolism. MethodsWe compared the metabolic changes and lymphatic function of wild-type and iNOS knockout mice fed a normal chow or high-fat diet for 16 weeks. To corroborate our in vivo findings, we analyzed the effects of reactive nitrogen species on isolated LECs. Finally, using a genetically engineered mouse model that allows partial ablation of the lymphatic system, we studied the effects of acute lymphatic injury on glucose and lipid metabolism in lean mice. ResultsThe mesenteric lymphatic vessels of obese wild-type animals were dilated, leaky, and surrounded by iNOS+ inflammatory cells with resulting increased accumulation of reactive nitrogen species when compared with lean wild-type or obese iNOS knockout animals. These changes in obese wild-type mice were associated with systemic glucose and lipid abnormalities, as well as decreased mesenteric LEC expression of lymphatic-specific genes, including vascular endothelial growth factor receptor 3 (VEGFR-3) and antioxidant genes as compared with lean wild-type or obese iNOS knockout animals. In vitro experiments demonstrated that isolated LECs were more sensitive to reactive nitrogen species than blood endothelial cells, and that this sensitivity was ameliorated by antioxidant therapies. Finally, using mice in which the lymphatics were specifically ablated using diphtheria toxin, we found that the interaction between metabolic abnormalities caused by obesity and lymphatic dysfunction is bidirectional. Targeted partial ablation of mesenteric lymphatic channels of lean mice resulted in increased accumulation of iNOS+ inflammatory cells and increased reactive nitrogen species. Lymphatic ablation also caused marked abnormalities in insulin sensitivity, serum glucose and insulin concentrations, expression of insulin-sensitive genes, lipid metabolism, and significantly increased systemic and mesenteric white adipose tissue (M-WAT) inflammatory responses. ConclusionsOur studies suggest that increased iNOS production in obese animals plays a key role in regulating lymphatic injury by increasing nitrosative stress. In addition, our studies suggest that obesity-induced lymphatic injury may amplify metabolic abnormalities by increasing systemic and local inflammatory responses and regulating insulin sensitivity. These findings suggest that manipulation of the lymphatic system may represent a novel means of treating metabolic abnormalities associated with obesity.