SciCombinator

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Concept: Lymph

169

The administration of interleukin 33 and deletion of IL-33 receptor, ST2 molecule, affects the induction of autoimmunity in different experimental models of human autoimmune diseases. The aim of this study was to analyze the effect of ST2 deletion on the induction of experimental autoimmune encephalomyelitis (EAE) in resistant BALB/c mice. Mice were immunized with MOG(35-55) peptide or disease was induced by passive transfer of encephalitogenic singenic cells and EAE was clinically and histologically evaluated. Expression of intracellular inflammatory cytokines, markers of activation and chemokine receptors on lymphoid tissue and CNS infiltrating mononuclear cells was analyzed by flow cytometry. We report here that deletion of ST2(-/-) molecule abrogates resistance of BALB/c mice to EAE induction based on clinical and histopathological findings. Brain and spinal cord infiltrates of ST2(-/-) mice had significantly higher number of CD4(+) T lymphocytes containing inflammatory cytokines compared to BALB/c WT mice. Adoptive transfer of ST2(-/-) primed lymphocytes induced clinical signs of the disease in ST2(-/-) as well as in WT mice. MOG(35-55) restimulated ST2(-/-) CD4(+) cells as well as ex vivo analyzed lymph node cells had higher expression of T-bet and IL-17, IFN-γ, TNF-α and GM-CSF in comparison with WT CD4(+) cells. ST2(-/-) mice had higher percentages of CD4(+) cells expressing chemokine receptors important for migration to CNS in comparison with WT CD4(+) cells. Draining lymph nodes of ST2(-/-) mice contained higher percentage of CD11c(+)CD11b(+)CD8(-) cells containing inflammatory cytokines IL-6 and IL-12 with higher expression of activation markers. Transfer of ST2(-/-) but not WT dendritic cells induced EAE in MOG(35-55) immunized WT mice. Our results indicate that ST2 deficiency attenuates inherent resistance of BALB/c mice to EAE induction by enhancing differentiation of proinflammatory antigen presenting cells and consecutive differentiation of encephalitogenic T cells in the draining lymph node rather than affecting their action in the target tissue.

Concepts: Immune system, Inflammation, Lymph node, Lymphatic system, Interleukin, Dendritic cell, Lymph, Lymph vessel

103

One of the characteristics of the central nervous system is the lack of a classical lymphatic drainage system. Although it is now accepted that the central nervous system undergoes constant immune surveillance that takes place within the meningeal compartment, the mechanisms governing the entrance and exit of immune cells from the central nervous system remain poorly understood. In searching for T-cell gateways into and out of the meninges, we discovered functional lymphatic vessels lining the dural sinuses. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes. The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system. The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction.

Concepts: Inflammation, White blood cell, Central nervous system, Brain, Lymph node, Lymphatic system, Lymph, Lymph vessel

92

Therapeutic drug monitoring (TDM) typically requires painful blood drawn from patients. We propose a painless and minimally-invasive alternative for TDM using hollow microneedles suitable to extract extremely small volumes (<1 nL) of interstitial fluid to measure drug concentrations. The inner lumen of a microneedle is functionalized to be used as a micro-reactor during sample collection to trap and bind target drug candidates during extraction, without requirements of sample transfer. An optofluidic device is integrated with this microneedle to rapidly quantify drug analytes with high sensitivity using a straightforward absorbance scheme. Vancomycin is currently detected by using volumes ranging between 50-100 μL with a limit of detection (LoD) of 1.35 μM. The proposed microneedle-optofluidic biosensor can detect vancomycin with a sample volume of 0.6 nL and a LoD of <100 nM, validating this painless point of care system with significant potential to reduce healthcare costs and patients suffering.

Concepts: Volume, Measurement, Illness, Integral, Pain, Analytical chemistry, Proposal, Lymph

48

Lymphocytes circulate through lymph nodes (LN) in search for antigen in what is believed to be a continuous process. Here, we show that lymphocyte migration through lymph nodes and lymph occurred in a non-continuous, circadian manner. Lymphocyte homing to lymph nodes peaked at night onset, with cells leaving the tissue during the day. This resulted in strong oscillations in lymphocyte cellularity in lymph nodes and efferent lymphatic fluid. Using lineage-specific genetic ablation of circadian clock function, we demonstrated this to be dependent on rhythmic expression of promigratory factors on lymphocytes. Dendritic cell numbers peaked in phase with lymphocytes, with diurnal oscillations being present in disease severity after immunization to induce experimental autoimmune encephalomyelitis (EAE). These rhythms were abolished by genetic disruption of T cell clocks, demonstrating a circadian regulation of lymphocyte migration through lymph nodes with time-of-day of immunization being critical for adaptive immune responses weeks later.

Concepts: Immune system, Lymph node, Adaptive immune system, Lymphatic system, Dendritic cell, Circadian rhythm, Lymph, Lymph vessel

40

The prevailing paradigm is that tuberculosis infection is initiated when patrolling alveolar macrophages and dendritic cells within the terminal alveolus ingest inhaled Mycobacterium tuberculosis (Mtb). However, definitive data for this model are lacking. Among the epithelial cells of the upper airway, a specialized epithelial cell known as a microfold cell (M cell) overlies various components of mucosa-associated lymphatic tissue. Here, using multiple mouse models, we show that Mtb invades via M cells to initiate infection. Intranasal Mtb infection in mice lacking M cells either genetically or by antibody depletion resulted in reduced invasion and dissemination to draining lymph nodes. M cell-depleted mice infected via aerosol also had delayed dissemination to lymph nodes and reduced mortality. Translocation of Mtb across two M cell transwell models was rapid and transcellular. Thus, M cell translocation is a vital entry mechanism that contributes to the pathogenesis of Mtb.

Concepts: Immune system, Gene, Lymph node, Epithelium, Tuberculosis, Lymphatic system, Skin, Lymph

28

OBJECTIVE: Endometrial cancer patients may benefit from systemic adjuvant chemotherapy, alone or in combination with targeted therapies. Prognostic and predictive markers are needed, however, to identify patients amenable for these therapies. METHODS: Primary endometrial tumors were genotyped for >100 hot spot mutations in genes potentially acting as prognostic or predictive markers. Mutations were correlated with tumor characteristics in a discovery cohort, replicated in independent cohorts and finally, confirmed in the overall population (n=1,063). RESULTS: PIK3CA, PTEN and KRAS mutations were most frequently detected, respectively in 172 (16.2%), 164 (15.4%) and 161 (15.1%) tumors. Binary logistic regression revealed that PIK3CA mutations were more common in high-grade tumors (OR=2.03; P=0.001 for grade 2 and OR=1.89; P=0.012 for grade 3 compared to grade 1), whereas a positive TP53 status correlated with type II tumors (OR=11.92; P<0.001) and PTEN mutations with type I tumors (OR=19.58; P=0.003). Conversely, FBXW7 mutations correlated with positive lymph nodes (OR=3.38; P=0.045). When assessing the effects of individual hot spot mutations, the H1047R mutation in PIK3CA correlated with high tumor grade and reduced relapse-free survival (HR=2.18; P=0.028). CONCLUSIONS: Mutations in PIK3CA, TP53, PTEN and FBXW7 correlate with high tumor grade, endometrial cancer type and lymph node status, whereas PIK3CA H1047R mutations serve as prognostic markers for relapse-free survival in endometrial cancer patients.

Concepts: Regression analysis, Cancer, Mutation, Oncology, Lymph node, Endometrial cancer, Lymph, Second grade

28

This study examines the relationship between the number of lymph nodes removed during modified radical neck dissection and the incidence of disease recurrence.

Concepts: Epidemiology, Cancer, Senescence, Lymph node, Lymph, Neck dissection

28

Simultaneous multiple free flaps have become a useful option in head and neck reconstructions. We performed a 10-year retrospective study between 2001 and 2010. There were 58 men and 1 woman. The overall mortality rate was 51.7%. The longest surviving patient is 9 years and 4 months, whereas the shortest surviving patient was 72 days. The mean survival period was 47.1 (6.8) months. Age (P = 0.755) and tumor size (P = 0.115) did not play a major role, but surgical margin, lymph node, and tumor recurrence were significant in patient survival with a P value of 0.026, 0.01, and 0.026, respectively. If wide excision with a margin that can be free of tumor can be performed, lymph nodes are not involved, and this is a primary tumor, then time and effort should be spent in a successful simultaneous multiple free flap reconstruction.

Concepts: Cancer, Patient, Lymph node, Lymph, Free flap

28

This study investigates the fluid flow through tissues where lymphatic drainage occurs. Lymphatic drainage requires the use of two valve systems, primary and secondary. Primary valves are located in the initial lymphatics. Overlapping endothelial cells around the circumferential lining of lymphatic capillaries are presumed to act as a unidirectional valve system. Secondary valves are located in the lumen of the collecting lymphatics and act as another unidirectional valve system; these are well studied in contrast to primary valves. We propose a model for the drainage of fluid by the lymphatic system that includes the primary valve system. The analysis in this work incorporates the mechanics of the primary lymphatic valves as well as the fluid flow through the interstitium and that through the walls of the blood capillaries. The model predicts a piecewise linear relation between the drainage flux and the pressure difference between the blood and lymphatic capillaries. The model describes a permeable membrane around a blood capillary, an elastic primary lymphatic valve and the interstitium lying between the two.

Concepts: Inflammation, Blood vessel, Capillary, Lymphatic system, Interstitial fluid, Endothelium, Cardiovascular system, Lymph

27

Cerebrospinal fluid (CSF) has been commonly accepted to drain through arachnoid projections from the subarachnoid space to the dural venous sinuses. However, a lymphatic component to CSF outflow has long been known. Here, we utilize lymphatic-reporter mice and high-resolution stereomicroscopy to characterize the anatomical routes and dynamics of outflow of CSF. After infusion into a lateral ventricle, tracers spread into the paravascular spaces of the pia mater and cortex of the brain. Tracers also rapidly reach lymph nodes using perineural routes through foramina in the skull. Using noninvasive imaging techniques that can quantify the transport of tracers to the blood and lymph nodes, we find that lymphatic vessels are the major outflow pathway for both large and small molecular tracers in mice. A significant decline in CSF lymphatic outflow is found in aged compared to young mice, suggesting that the lymphatic system may represent a target for age-associated neurological conditions.

Concepts: Spinal cord, Brain, Cerebrospinal fluid, Lymph, Meninges, Ventricular system, Arachnoid mater, Pia mater