Lymphatic function and immune regulation in health and disease

Lymphatic complication in open venous harvesting versus endoscopic venous harvesting: a systematic review and meta-analysis

BACKGROUND

The methods for saphenous vein (SV) harvesting include bridging vein harvesting (BVH), open vein harvesting (OVH), and endoscopic vein harvesting (EVH). Lymphatic complications, such as lymphatic leak, lymphedema, lymphangitis, and lymphocele, can arise following SV-harvesting surgery. This study aims to compare the incidence of lymphatic complications in SV harvesting using the OVH surgical method versus EVH.

METHODS

We have systematically searched databases including Scopus, PubMed, and Web of Science until April 2024. Studies were considered eligible for inclusion if they performed SV harvesting and compared lymphatic complications in the EVH with OVH or BVH. Various lymphatic complications and follow-up periods were extracted. A meta-analysis was conducted comparing the relative risk (RR) of lymphatic complications in the EVH group versus the OVH group.

RESULTS

Twelve studies were included. A total of 1934 patients were involved and the majority were male. Follow-up times were from 6 days to 34 months. Results of the meta-analysis showed that the pooled lymphatic complications, lymphatic leak, and lymphedema are significantly higher in OVH versus EVH (RR = 6.78, p value < 0.01; RR = 17.33, p value < 0.01; RR = 8.88, p value < 0.01, respectively). No significant differences in lymphocele rates between the two methods (RR = 1.2, p value = 0.77). Both short-term and long-term follow-ups showed elevated lymphatic complication risks in OVH relative to EVH (RR = 4.91, p value < 0.01; RR = 30.27, p value = 0.03, respectively).

CONCLUSION

EVH is linked to reduced rates of lymphatic complications. Also, OVH had a higher risk of lymphatic complications in the short and long term compared to EVH.

Liver-draining portal lymph node responds to enteric nematode infection by generating highly parasite-specific follicular T helper and B cell responses

Introduction

While research on the gut-liver axis in non-communicable liver diseases has expanded exponentially, few studies have investigated the liver-gut relationship in the context of gastrointestinal nematode infections. This study aimed to determine whether liver-draining lymph nodes (LLNs) contribute to the immune response against a strictly enteric nematode infection.

Methods

We analyzed the cellular and functional immune responses in the portal (PLN) and celiac (CLN) liver-draining lymph nodes following infection with the small intestinal nematode Heligmosomoides (polygyrus) bakeri (H. bakeri). The composition of dendritic cells and CD4+ T cell subsets in LLNs was compared to the mesenteric lymph nodes (MLN), the primary draining site of gut infections. Additionally, we examined Th2 effector cell expansion, plasmablast generation, and B cell activation across these lymphoid sites.

Results

Both PLN and CLN exhibited increased cellularity at d14 post-infection. The immune profile in CLN closely resembled that of MLN, characterized by a robust expansion of GATA-3+ Th2 effector cells at days 6 and 14 post-infection. This was accompanied by an early plasmablast response, producing low-affinity IgG1 antibodies targeting immune-dominant excretory-secretory (ES) products. In contrast, PLN showed weaker Th2 responses and lower early plasma cell responses compared to MLN and CLN. However, PLN displayed strong follicular T helper (TFH) activity, with a B cell profile biased toward germinal center reactions. This led to high-affinity IgG1 antibodies specifically binding VAL-1 and ACE-1.

Discussion

These findings demonstrate, for the first time, that liver-draining lymph nodes actively participate in the adaptive immune response to enteric nematode infections. While MLN and CLN function synergistically in generating early Th2 effector cells and rapid extrafollicular IgG1+ plasma cell responses, PLN specializes in TFH-driven germinal center reactions and affinity maturation.

Murine gut microbiota dysbiosis via enteric infection modulates the foreign body response to a distal biomaterial implant

The gut microbiota influences systemic immunity and the function of distal tissues, including the brain, liver, skin, lung, and muscle. However, the role of the gut microbiota in the foreign body response (FBR) and fibrosis around medical implants is largely unexplored. To investigate this connection, we perturbed the homeostasis of the murine gut microbiota via enterotoxigenic Bacteroides fragilis (ETBF) infection and implanted the synthetic polymer polycaprolactone (PCL) into a distal muscle injury. ETBF infection in mice led to increased neutrophil and γδ T cell infiltration into the PCL implant site. ETBF infection alone promoted systemic inflammation and increased levels of neutrophils in the blood, spleen, and bone marrow. At the PCL implant site, we found significant changes in the transcriptome of sorted fibroblasts but did not observe gross ETBF- induced differences in the fibrosis levels after 6 weeks. These results demonstrate the ability of the gut microbiota to mediate long-distance effects such as immune and stromal responses to a distal biomaterial implant.

Significance Statement

The foreign body response to implants leads to chronic inflammation and fibrosis that can be highly variable in the general patient population. Here, we demonstrate that gut dysbiosis via enteric infection promoted systemic inflammation and increased immune cell recruitment to an anatomically distant implant site. These results implicate the gut microbiota as a potential source of variability in the clinical biomaterial response and illustrate that the local tissue environment can be influenced by host factors that modulate systemic interactions.

Sodium-Directed Crosstalk Between Immune Cells and Lymphatic Vessels

PURPOSE OF REVIEW

The role of the lymphatic system in clearing extravasated fluids, lipid transport, and immune surveillance is well established, and lymphatic vasculature can provide a vital role in facilitating crosstalk among various organ systems. Lymphatic vessels rely on intrinsic and local factors to absorb and propel lymph from the interstitium back to the systemic circulation. The biological implications of local influences on lymphatic vessels are underscored by the exquisite sensitivity of these vessels to environmental stimuli. This review is intended to highlight the role of sodium within the local environment in mediating lymphatic and immune cell interactions that contribute to changes in function and disease progression.

RECENT FINDINGS

We discuss evidence that accumulation of interstitial sodium modulates lymphatic growth, pumping dynamics, and permeability of renal lymphatics, which involves activation of sodium potassium chloride co-transporter (NKCC1) in lymphatic endothelial cells. These recent findings complement observations that sodium activates immune cells via the epithelial sodium channel (ENaC), leading to the formation and accumulation of lipid oxidation products, isolevuglandins (IsoLGs), in antigen presenting cells, which in turn promotes T cell activation and vasculopathy. In addition, we will underscore the physiologic relevance of altered interplay between immune cells and lymphatics in the sodium avid state that characterizes kidney diseases and consider how sodium accumulation in the interstitial compartment of the kidney modulates the lymphatic network and the interactions between renal lymphatics and activated immune cells. Finally, this article calls attention to persisting knowledge gaps and stresses the need for additional studies to identify salt-sensing mechanisms, including sodium-activated immune cells and lymphatic endothelial cell interactions, for targeted therapeutic interventions in the setting of renal disease.

Pharmacological Properties of Platycarpha glomerata Extracts-A Plant Used to Treat and Manage Elephantiasis

Platycarpha glomerata (Thunb.) Less. has recently become a plant species of interest to researchers due to its biological activities and less toxic effects. Therefore, the aim of the study is to evaluate the in vitro anticancer potential and phytochemical constituents of P. glomerata plant extracts. Phytochemical screening and FTIR were carried out using standard methods. The antioxidant activity was accessed by determining its ability to scavenge the DPPH radical and nitric oxide radical, whereas the anticancer activity against prostate (DU-145 and PC-3), human T-lymphocyte (SKU-T), gastric adenocarcinoma (AGS), and human prostatic epithelial (PNTA1) cell line was evaluated using the MTT assay. The phytochemical analysis revealed the presence of tannins, flavonoids, saponins, steroids, terpenoids, and cardiac glycosides. The FTIR spectrum for the aqueous extract displayed characteristic peaks for O-H, C=O, C=C, and =C-H stretch. The aqueous ethanol and methanol extracts showed significant dose-dependent DPPH radical scavenging capacity. The aqueous, ethanol, and methanol extracts showed minimum NO scavenging activity of 4.3%, 9.6%, and 11.7% at 2500 µg/mL. The water extract demonstrated good activity against S. aureus, E. coli, and B. pumilus with an MIC of 0.195 mg/mL. The ethanol and methanol extracts significantly reduced the percentage proliferation of DU-145, PC-3, and SKU-T cells at 100 μg/mL. These extracts demonstrated strong dose-dependent DPPH and NO scavenging and antibacterial and cell proliferation inhibition activities. The strong bioactivity of P. glomerata makes it a good candidate for the isolation and identification of active compounds for anticancer and related illnesses.

An Update on the Role of Lymphatic Function in Skin Inflammatory Disorders: A Scoping Review

The lymphatic system is essential in maintaining skin health through coordinated immunological actions. This review explores the relationship between lymphatic function and skin health, as well as the impact of lymphatic dysfunction in the development and progression of inflammatory skin disorders. A systemic search was conducted in the Web of Science, Embase, and Ovid MEDLINE databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. Included studies were peer-reviewed human or animal research published in English from 2014 to 2024, focusing on inflammatory skin disorders, including skin cancer, autoimmune skin diseases, and infectious skin diseases. A total of 1232 citations were identified, with 37 studies meeting the eligibility criteria after assessment and critical appraisal. The review's findings highlight the essential role of lymphatics in maintaining skin health, mitigating inflammatory, infectious, and skin cancer-related processes, and delaying the effects of skin aging. The mechanisms underlying lymphatic function in these processes are complex, with some aspects needing further investigation. However, the evidence indicates that a well-functioning skin lymphatic system, supported by various cytokines, aids in reducing the inflammatory state, reduces inflammation, alleviates lymphedema, and prevents lymphatic stasis, which can increase infection risk. Several studies demonstrated that restoring lymphatic function through improved neutrophil migration and cytokine responses reduces the spread of infectious diseases.

Dendritic cell activation by iron oxide nanoparticles depends on the extracellular environment

Nanoparticles can exert immune modulating effects in a host depending on composition, mode of administration, and type of disease. Although the specific mechanisms of nanoparticle-induced immune responses remain unclear, their uptake by macrophages and other phagocytic innate immune cells is considered to be a key event. Our objective here was to ascertain if nanoparticle-mediated activation of dendritic cells (DCs) occurs in vitro or in vivo when exposed to hydroxyethyl starch-coated iron oxide nanoparticles. For the present studies, our choice of nanoparticles, animal model, and experimental design is motivated by our previously published observations that systemic exposure can induce antitumor adaptive immune responses in mouse models of metastatic breast cancer. Here, we began by assessing the potential toxicity of systemic exposure to commercially available starch-coated Bionized Nanoferrite® nanoparticles (BP) by measuring body weight, complete blood count, and enzyme parameters in healthy FVB/NJ mice after repeated BP dosing. We observed no evidence of toxicity at doses up to 25 mg Fe per mouse, five-fold higher than those used in subsequent in vivo experiments. We then measured the expression of surface maturation markers (CD86, MHC II) in DCs incubated with BP in vitro. Although DCs cultured with BP revealed high levels of nanoparticle uptake, neither JAWSII dendritic cells nor bone marrow derived dendritic cells (BMDCs) showed significant changes in marker expression to indicate stimulation of maturation and effector function. To assess whether BP interactions in vivo produced different effects, we analyzed CD80, CD86, and MHC II expression of DCs recovered from the livers, spleens, bone marrows, and lymph nodes of mice injected once with BP (5 mg Fe). Interestingly, only DCs in spleens and bone marrow cells responded to BP exposure. DCs recovered from other organs showed no evidence of increased activation. These findings highlight complex interactions between living systems and nanoparticles, and their potential to mediate context-specific and selective activation of innate immune cells. Our study also emphasizes that results obtained from in vitro experiments must be interpreted with caution, as they may not faithfully represent responses in living systems.

In vivo spatiotemporal characterizing diverse body transportation of optical labeled high immunity aluminium adjuvants with photoacoustic tomography

Vaccine development requires high-resolution, in situ, and visual adjuvant technology. To address this need, this work proposed a novel adjuvant labeling that involved indocyanine green (ICG) and bovine serum albumin (BSA) with self-assembled aluminium adjuvant (Alum), which was called BSA@ICG@Alum. This compound exhibited excellent photoacoustic properties and has been confirmed its safety, biocompatibility, high antigen binding efficiency, and superior induction of immune response. Photoacoustic tomography (PAT) tracked the distribution of Alum in lymph nodes (LNs) and lymphatic vessels in real time after diverse injection modalities. The non-invasive imaging approach revealed that BSA@ICG@Alum was transported to the draining LNs 60 min after intramuscular injection and to distal LNs within 30 min after lymph node injection. In conclusion, PAT enabled real-time three-dimensional and quantitative visualization, thus offering a powerful tool for advancing vaccine design by providing critical insights into adjuvant transport and immune system activation.

Reactive Changes in Lymph Node Structure in Peritonitis and during Treatment with a New Antibiotic

The effect of a new antibiotic peptomide A-70 on changes in the mesenterial lymph nodes caused by experimental peritonitis was studied. Differences in the morphological changes in rat lymph nodes in peritonitis and against the background of antibiotic therapy were revealed. Lymph nodes responded to peritoneal inflammation by reducing the area of cortical structures and expansion of the sinus system, which indicates a decrease in drainage-detoxification and immune function and determines unfavorable outcome of peritonitis. Antibiotic therapy reduced inflammatory manifestations and toxic pressure on the lymph system and potentiated the reactive response of the mesenteric lymph nodes: the size of lymphoid nodes and the paracortical T-dependent zone increased against the background of shrinkage of the sinus system, which attested to activation of the lymphopoietic function and immune response of lymph nodes in peritonitis. The observed changes attested to favorable prognosis of peritonitis treated with antibiotic peptomide A-70.

Unveiling the Uncommon: A Rare Case of Group A Streptococcus Axillary Lymphadenitis With Ambiguous Presentation Leading to Multiple Misdiagnoses

Axillary lymphadenitis in adults presents a diagnostic challenge due to its diverse etiology and variable clinical manifestations. We present a rare case of suppurative Group A Streptococcus (GAS) axillary lymphadenitis secondary to a puncture wound, emphasizing the critical importance of differential diagnosis and immediate intervention. A 36-year-old male initially presented with left axillary pain and discomfort following a traumatic injury to the left thumb. Despite multiple healthcare encounters and misdiagnoses including viral illness and shingles, the patient's condition deteriorated, manifesting as fever, edema, and erythema in the left axilla. This case underscores the paramount significance of considering lymphadenitis in patients with axillary symptoms, particularly following trauma or skin breaches. Early recognition and appropriate management are crucial to prevent grave complications such as abscess formation, thrombophlebitis, and bacteremia. Streptococcal axillary lymphadenitis should be included at the forefront of the differential diagnosis to expedite treatment and mitigate potential life-threatening consequences associated with delayed diagnosis.

The Role of Inflammation in Lymphedema: A Narrative Review of Pathogenesis and Opportunities for Therapeutic Intervention

Lymphedema is a chronic and progressive disease of the lymphatic system characterized by inflammation, increased adipose deposition, and tissue fibrosis. Despite early hypotheses identifying lymphedema as a disease of mechanical lymphatic disruption alone, the progressive inflammatory nature underlying this condition is now well-established. In this review, we provide an overview of the various inflammatory mechanisms that characterize lymphedema development and progression. These mechanisms contribute to the acute and chronic phases of lymphedema, which manifest clinically as inflammation, fibrosis, and adiposity. Furthermore, we highlight the interplay between current therapeutic modalities and the underlying inflammatory microenvironment, as well as opportunities for future therapeutic development.

Sleep disorders and Alzheimer's disease pathophysiology: The role of the Glymphatic System. A scoping review

BACKGROUND

Alzheimer's disease (AD) is highly intertwined with sleep disturbances throughout its whole natural history. Sleep consists of a major compound of the functionality of the glymphatic system, as the synchronized slow-wave activity during NREM facilitates cerebrospinal and interstitial long-distance mixing.

OBJECTIVE

The present study undertakes a scoping review of research on the involvement of the glymphatic system in AD-related sleep disturbances.

DESIGN

we searched Medline, Embase, PsychInfo and HEAL-link databases, without limitations on date and language, along with reference lists of relevant reviews and all included studies. We included in vivo, in vitro and post-mortem studies examining glymphatic implications of sleep disturbances in human populations with AD spectrum pathology. A thematic synthesis of evidence based on the extracted content was applied and presented in a narrative way.

RESULTS

In total, 70 original research articles were included and were grouped as following: a) Protein aggregation and toxicity, after sleep deprivation, along with its effects on sleep architecture, b) Glymphatic Sequalae in SDB, yielding potential glymphatic markers c) Circadian Dysregulation, d) Possible Interventions.

CONCLUSIONS

this review sought to provide insight into the role of sleep disturbances in AD pathogenesis, in the context of the glymphatic disruption.

Microfluidic-Based Reconstitution of Functional Lymphatic Microvasculature: Elucidating the Role of Lymphatics in Health and Disease

The knowledge of the blood microvasculature and its functional role in health and disease has grown significantly attributable to decades of research and numerous advances in cell biology and tissue engineering; however, the lymphatics (the secondary vascular system) has not garnered similar attention, in part due to a lack of relevant in vitro models that mimic its pathophysiological functions. Here, a microfluidic-based approach is adopted to achieve precise control over the biological transport of growth factors and interstitial flow that drive the in vivo growth of lymphatic capillaries (lymphangiogenesis). The engineered on-chip lymphatics with in vivo-like morphology exhibit tissue-scale functionality with drainage rates of interstitial proteins and molecules comparable to in vivo standards. Computational and scaling analyses of the underlying transport phenomena elucidate the critical role of the three-dimensional geometry and lymphatic endothelium in recapitulating physiological drainage. Finally, the engineered on-chip lymphatics enabled studies of lymphatic-immune interactions that revealed inflammation-driven responses by the lymphatics to recruit immune cells via chemotactic signals similar to in vivo, pathological events. This on-chip lymphatics platform permits the interrogation of various lymphatic biological functions, as well as screening of lymphatic-based therapies such as interstitial absorption of protein therapeutics and lymphatic immunomodulation for cancer therapy.

Systems immunology spanning tumors, lymph nodes, and periphery

The immune system defines a complex network of tissues and cell types that orchestrate responses across the body in a dynamic manner. The local and systemic interactions between immune and cancer cells contribute to disease progression. Lymphocytes are activated in lymph nodes, traffic through the periphery, and impact cancer progression through their interactions with tumor cells. As a result, therapeutic response and resistance are mediated across tissues, and a comprehensive understanding of lymphocyte dynamics requires a systems-level approach. In this review, we highlight experimental and computational methods that can leverage the study of leukocyte trafficking through an immunomics lens and reveal how adaptive immunity shapes cancer.

Lymphangiogenesis after nonvascularized lymph node transplantation: Lymphangiographic findings in mice and minipigs

The establishment of new connections after NVLNT (non-vascularized lymph node transplantation) is still poorly understood. The purpose of this study was to investigate lymphatic connections after NVLNT using lymphangiography. In a mice model, 40 mice were allocated to undergo NVLNT or sham surgery. On day 21 after NVLNT, the lymphatic vessels were observed on near-infrared fluorescence imaging with indocyanine green. In a minipig model, 12 minipigs underwent NVLNT. On day 14 after NVLNT, the transplanted lymph node and donor site were checked by ultrasound, and minipigs with viable transplanted LNs were allocated to lipiodol lymphangiography or MR lymphangiography groups. Transplanted LN engraftment was examined with immunohistochemical staining. After NVLNT in mice, the signal intensities in the popliteal region at 3 minutes and 5 minutes were higher in the transplanted side than the control side (21.3 ± 8.1 vs. 11.0 ± 4.6 at 3 minutes, 26.7 ± 6.8 vs. 19.7 ± 5.9 at 5 minutes), while in the sham group, there were no significant differences between sides. In minipigs, lipiodol lymphangiography (n = 5) showed Lipiodol accumulation in transplanted LNs with innumerable newly formed lymphatic vessels and lymphovenous shunts. MR lymphangiography (n = 5) showed higher enhancement on the transplanted side compared to the control side. Histology showed successful engraftment of transplanted LNs in 16 out of 20 (80%) mice and 9 out of 12 (75%) minipigs. Omnidirectional lymphangiogenesis forming a dense lymphatic network and spontaneous formation of lymphovenous shunts were shown after NVLNT.

The lymphatic system favours survival of a unique T. brucei population

Trypanosoma brucei colonise and multiply in the blood vasculature, as well as in various organs of the host's body. Lymph nodes have been previously shown to harbour large numbers of parasites, and the lymphatic system has been proposed as a key site that allows T. brucei distribution through, and colonization of the mammalian body. However, visualization of host-pathogen interactions in the lymphatic system has never captured dynamic events with high spatial and temporal resolution throughout infection. In our work, we used a mixture of tools including intravital microscopy and ex vivo imaging to study T. brucei distribution in 20 sets of lymph nodes. We demonstrate that lymph node colonization by T. brucei is different across lymph node sets, with the most heavily colonised being the draining lymph nodes of main tissue reservoirs: the gonadal white adipose tissue and pancreas. Moreover, we show that the lymphatic vasculature is a pivotal site for parasite dispersal, and altering this colonization by blocking LYVE-1 is detrimental for parasite survival. Additionally, parasites within the lymphatic vasculature have unique morphological and behavioural characteristics, different to those found in the blood, demonstrating that across both types of vasculature, these environments are physically separated. Finally, we demonstrate that the lymph nodes and the lymphatic vasculature undergo significant alterations during T. brucei infection, resulting in oedema throughout the host's body.

Synthetic hyaluronic acid coating preserves the phenotypes of lymphatic endothelial cells

Lymphatic endothelial cells (LECs) play a critical role in the formation and maintenance of the lymphatic vasculature, which is essential for the immune system, fluid balance, and tissue repair. However, LECs are often difficult to study in vivo and in vitro models that accurately mimic their behaviors and phenotypes are limited. In particular, LECs have been shown to lose their lymphatic markers over time while being cultured in vitro, which reflect their plasticity and heterogeneity in vivo. Since LECs uniquely express lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), we hypothesized that surface coating with hyaluronic acid (HA) can preserve LEC phenotypes and functionalities. Dopamine conjugated hyaluronic acid (HA-DP) was synthesized with 42% degree of substitution to enable surface modification and conjugation onto standard tissue culture plates. Compared to fibronectin coating and tissue culture plate controls, surface coating with HA-DP was able to preserve lymphatic markers, such as prospero homeobox protein 1 (Prox1), podoplanin (PDPN), and LYVE-1 over several passages in vitro. LECs cultured on HA-DP expressed lower levels of focal adhesion kinase (FAK) and YAP/TAZ, which may be responsible for the maintenance of the lymphatic characteristics. Collectively, the HA-DP coating may provide a novel method for culturing human LECs in vitro toward more representative studies in basic lymphatic biology and lymphatic regeneration.

Assessment of factors influencing glymphatic activity and implications for clinical medicine

The glymphatic system is a highly specialized fluid transport system in the central nervous system. It enables the exchange of the intercellular fluid of the brain, regulation of the movement of this fluid, clearance of unnecessary metabolic products, and, potentially, brain immunity. In this review, based on the latest scientific reports, we present the mechanism of action and function of the glymphatic system and look at the role of factors influencing its activity. Sleep habits, eating patterns, coexisting stress or hypertension, and physical activity can significantly affect glymphatic activity. Modifying them can help to change lives for the better. In the next section of the review, we discuss the connection between the glymphatic system and neurological disorders. Its association with many disease entities suggests that it plays a major role in the physiology of the whole brain, linking many pathophysiological pathways of individual diseases.

Higher order diffusion imaging as a putative index of human sleep-related microstructural changes and glymphatic clearance

The brain has a unique macroscopic waste clearance system, termed the glymphatic system which utilises perivascular tunnels surrounded by astroglia to promote cerebrospinal-interstitial fluid exchange. Rodent studies have demonstrated a marked increase in glymphatic clearance during sleep which has been linked to a sleep-induced expansion of the extracellular space and concomitant reduction in intracellular volume. However, despite being implicated in the pathophysiology of multiple human neurodegenerative disorders, non-invasive techniques for imaging glymphatic clearance in humans are currently limited. Here we acquired multi-shell diffusion weighted MRI (dwMRI) in twenty-one healthy young participants (6 female, 22.3 ± 3.2 years) each scanned twice, once during wakefulness and once during sleep induced by a combination of one night of sleep deprivation and 10 mg of the hypnotic zolpidem 30 min before scanning. To capture hypothesised sleep-associated changes in intra/extracellular space, dwMRI were analysed using higher order diffusion modelling with the prediction that sleep-associated increases in interstitial (extracellular) fluid volume would result in a decrease in diffusion kurtosis, particularly in areas associated with slow wave generation at the onset of sleep. In line with our hypothesis, we observed a global reduction in diffusion kurtosis (t15=2.82, p = 0.006) during sleep as well as regional reductions in brain areas associated with slow wave generation during early sleep and default mode network areas that are highly metabolically active during wakefulness. Analysis with a higher-order representation of diffusion (MAP-MRI) further indicated that changes within the intra/extracellular domain rather than membrane permeability likely underpin the observed sleep-associated decrease in kurtosis. These findings identify higher-order modelling of dwMRI as a potential new non-invasive method for imaging glymphatic clearance and extend rodent findings to suggest that sleep is also associated with an increase in interstitial fluid volume in humans.

L-selectin-dependent and -independent homing of naïve lymphocytes through the lung draining lymph node support T cell response to pulmonary Mycobacterium tuberculosis infection

Recruiting large numbers of naïve lymphocytes to lymph nodes is critical for mounting an effective adaptive immune response. While most naïve lymphocytes utilize homing molecule L-selectin to enter lymph nodes, some circulating cells can traffic to the lung-draining mediastinal lymph node (mLN) through lymphatics via the intermediate organ, lung. However, whether this alternative trafficking mechanism operates in infection and contributes to T cell priming are unknown. We report that in pulmonary Mycobacterium tuberculosis-infected mice, homing of circulating lymphocytes to the mLN is significantly less efficient than to non-draining lymph node. CD62L blockade only partially reduced the homing of naïve T lymphocytes, consistent with L-selectin-independent routing of naïve lymphocytes to the site. We further demonstrated that lymphatic vessels in infected mLN expanded significantly and inhibiting lymphangiogenesis with a vascular endothelial growth factor receptor 3 kinase inhibitor reduced the recruitment of intravenously injected naïve lymphocytes to the mLN. Finally, mycobacterium-specific T cells entering via the L-selectin-independent route were readily activated in the mLN. Our study suggests that both L-selectin-dependent and -independent pathways contribute to naïve lymphocyte entry into mLN during M. tuberculosis infection and the latter pathway may represent an important mechanism for orchestrating host defence in the lungs.

Vascular regulation of disseminated tumor cells during metastatic spread

Cancer cells can travel to other organs via interconnected vascular systems to form new lesions in a process known as metastatic spread. Unfortunately, metastasis remains the leading cause of patient lethality. In recent years, it has been demonstrated that physical cues are just as important as chemical and genetic perturbations in driving changes in gene expression, cell motility, and survival. In this concise review, we focus on the physical cues that cancer cells experience as they migrate through the lymphatic and blood vascular networks. We also present an overview of steps that may facilitate organ specific metastasis.

Understanding key vectors and vector-borne diseases associated with freshwater ecosystem across Africa: Implications for public health

The emerging and re-emerging vector-borne diseases transmitted by key freshwater organisms have remained a global concern. As one of the leading biodiversity hotspots, the African ecoregion is suggested to harbour the highest number of freshwater organisms globally. Among the commonly found organisms in the African ecoregion are mosquitoes and snails, with a majority of their life cycle in freshwater, and these freshwater organisms can transmit diseases or serve as carriers of devastating diseases of public health concerns. However, synthetic studies to link the evident abundant presence and wide distribution of these vectors across the freshwater ecosystems in Africa with the increasing emerging and re-emerging vector-borne diseases in Africa are still limited. Here, we reviewed documented evidence on vector-borne diseases and their transmission pathways in Africa to reduce the knowledge gap on the factors influencing the increasing emerging and re-emerging vector-borne diseases across Africa. We found the population distributions or abundance of these freshwater organisms to be increasing, which is directly associated with the increasing emerging and re-emerging vector-borne diseases across Africa. Furthermore, we found that although the current changing environmental conditions in Africa affect the habitats of these freshwater organisms, current changing environmental conditions may not be suppressing the population distributions or abundance of these freshwater organisms. Instead, we found that these freshwater organisms are extending their geographic ranges across Africa, which may have significant public health implications in Africa. Thus, our study demonstrates the need for future studies to integrate the environmental conditions of vectors' habitats to understand if these environmental conditions directly or indirectly influence the vectorial capacities and transmission abilities of vectors of diseases. We propose that such studies will be necessary to guide policymakers in making informed policies to help control vector-borne diseases.

Tissue Engineering Approaches to Uncover Therapeutic Targets for Endothelial Dysfunction in Pathological Microenvironments

Endothelial cell dysfunction plays a central role in many pathologies, rendering it crucial to understand the underlying mechanism for potential therapeutics. Tissue engineering offers opportunities for in vitro studies of endothelial dysfunction in pathological mimicry environments. Here, we begin by analyzing hydrogel biomaterials as a platform for understanding the roles of the extracellular matrix and hypoxia in vascular formation. We next examine how three-dimensional bioprinting has been applied to recapitulate healthy and diseased tissue constructs in a highly controllable and patient-specific manner. Similarly, studies have utilized organs-on-a-chip technology to understand endothelial dysfunction's contribution to pathologies in tissue-specific cellular components under well-controlled physicochemical cues. Finally, we consider studies using the in vitro construction of multicellular blood vessels, termed tissue-engineered blood vessels, and the spontaneous assembly of microvascular networks in organoids to delineate pathological endothelial dysfunction.

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.

Can YouTube be used as an educational tool in lymphedema rehabilitation?

Background

Lymphedema is defined as the abnormal accumulation of interstitial fluid and fibro-adipose tissues resulting from injury, infection, or congenital abnormalities of the lymphatic system. The gold standard approach in the treatment of lymphedema is Complete Decongestive Therapy and it has many components that require practical knowledge and skills. YouTube can be a useful tool to provide these skills to healthcare professionals and patients. The aim of this study was to examine the videos about lymphedema rehabilitation on YouTube and analyze their technical features, sources, contents, educational value and reliability.

Methods

The YouTube database was searched using the “lymphedema rehabilitation”, “lymphedema treatment”, “complete decongestive therapy”, “lymphedema massage”, and “lymphedema exercises” keywords. Two reviewers (Physical medicine and rehabilitation specialist) assessed videos for educational quality using a Global Quality Scale (GQS). To evaluate the reliability the 5-point Discern scale was used.

Results

A total of 90 videos, which met the inclusion criteria were included in the analysis. The mean duration of the videos was 8.9 ± 10.5 min. The mean number of daily views was 22.7 ± 47.1 for a day. The majority of the videos were created to inform patients (57.8%).The uploaders were mostly private healthcare institutions or healthcare professionals (65.6%). Information providers were lymphedema therapists mostly (63.3%). Manual lymphatic drainage was observed to stand out as the most mentioned lymphedema rehabilitation component on YouTube. The mean of reliability and GQS scores of the videos were 2.2 ± 1.0 and 2.7 ± 1.0, respectively.

Conclusions

The biggest obstacle for YouTube to be an excellent source of information is that it hosts large volumes of uncontrolled and low-quality data. When Youtube content related to lymphedema rehabilitation was examined, it was observed that many videos were quite insufficient and incomplete even though there were useful videos. If careful controlling measures are implemented and if medical videos aim to meet reliability and GQS criteria, YouTube can become an effective and useful source of information for lymphedema rehabilitation.

Bacterial Involvement in Progression and Metastasis of Colorectal Neoplasia

While the gut microbiome is composed of numerous bacteria, specific bacteria within the gut may play a significant role in carcinogenesis, progression, and metastasis of colorectal carcinoma (CRC). Certain microbial species are known to be associated with specific cancers; however, the interrelationship between bacteria and metastasis is still enigmatic. Mounting evidence suggests that bacteria participate in cancer organotropism during solid tumor metastasis. A critical review of the literature was conducted to better characterize what is known about bacteria populating a distant site and whether a tumor depends upon the same microenvironment during or after metastasis. The processes of carcinogenesis, tumor growth and metastatic spread in the setting of bacterial infection were examined in detail. The literature was scrutinized to discover the role of the lymphatic and venous systems in tumor metastasis and how microbes affect these processes. Some bacteria have a potent ability to enhance epithelial-mesenchymal transition, a critical step in the metastatic cascade. Bacteria also can modify the microenvironment and the local immune profile at a metastatic site. Early targeted antibiotic therapy should be further investigated as a measure to prevent metastatic spread in the setting of bacterial infection.

Bilateral hyperplasia of choroid plexus with severe CSF production: a case report and review of the glymphatic system

BACKGROUND

An important feature of hydrocephalus is the alteration of the cerebral spinal fluid (CSF) homeostasis. New insights in the understanding of production, secretion, and absorption of CSF, along with the discovery of the glymphatic system (GS), can be useful for a better understanding and treatment of hydrocephalus in disorders with CSF overproduction.

CASE DESCRIPTION

A 1-year-old patient was diagnosed with communicating hydrocephalus; ventricle peritoneal shunt (VPS) is installed and ascites developed. VPS is exposed, yielding volumes of 1000-1200ml/day CSF per day. MRI is performed showing generalized choroidal plexus hyperplasia. Bilateral endoscopic coagulation of thechoroid plexus was performed in 2 stages (CPC) however the high rate of CSF production persisted, needing a bilateral plexectomy through septostomy, which finally decreased the CSF outflow.

DISCUSSION

New knowledge about the CSF physiology will help to propose better treatment depending on the cause of the hydrocephalus. The GS is becoming an additional reason to better study and develop new therapies focused of the modulation of alternative CSF reabsorption.

CONCLUSION

Despite the current knowledge about hydrocephalus, we remain without a complete understanding of the pathophysiology of this condition. GS could be more important than conventional concept of reabsorption of CSF in the arachnoid villi, therefore GS could be a new key point, which will guide future investigations.

The development and physiological and pathophysiological functions of resident macrophages and glial cells

In the past, brain function and the onset and progression of neurological diseases have been studied in a neuron-centric manner. However, in recent years the focus of many neuroscientists has shifted to other cell types that promote neurodevelopment and contribute to the functionality of neuronal networks in health and disease. Particularly microglia and astrocytes have been implicated in actively contributing to and controlling neuronal development, neuroinflammation, and neurodegeneration. Here, we summarize the development of brain-resident macrophages and astrocytes and their core functions in the developing brain. We discuss their contribution and intercellular crosstalk during tissue homeostasis and pathophysiology. We argue that in-depth knowledge of non-neuronal cells in the brain could provide novel therapeutic targets to reverse or contain neurological diseases.

Harnessing biomaterials for lymphatic system modulation

The lymphatic system plays an integral part in regulating immune cell trafficking and the transport of macromolecules. However, its influence on disease progression and drug uptake is understood less than that of the vascular system. To bridge this knowledge gap, biomaterials can be used to investigate the lymphatic system and to provide novel understanding into complex disease processes, including cancer metastasis and inflammation. Insight gained from these mechanistic studies can be further used to design innovative biomaterials to modulate the immune system, improve drug delivery, and promote tissue regeneration. This review article focuses on recent advances in (i) biomaterials used for lymphatic vessel formation, (ii) models for studying lymphatic-immune cells interactions, (iii) pharmaceuticals and their interactions with the lymphatic system, (iv) and strategies for drug delivery via the lymphatic system. Finally, several challenges regarding adopting biomaterials for immunomodulation and future perspectives are discussed. STATEMENT OF SIGNIFICANCE: The lymphatic system plays an integral part in regulating immune cell trafficking and the transport of macromolecules. However, its influence on disease progression and drug uptake is understood less than that of the vascular system. This review article focuses on recent progresses in biomaterials to investigate the lymphatic system and to provide novel understanding into complex disease states. Insight gained from these mechanistic studies can be further used to design innovative biomaterials to modulate the immune system, improve drug delivery, and promote tissue regeneration. Finally, a number of challenges in adopting biomaterials for immunomodulation and future perspectives are discussed.

Glymphatics: A Transformative Development in Medical Neuroscience Relevant to Injuries in Military Central Nervous System

INTRODUCTION

The glia-operated glymphatic system, analogous to but separate from the lymphatics in the periphery, is unique to brain and retina, where it is very closely aligned with the arteriolar system. This intimate relationship leads to a "blood vessel like" distribution pattern of glymphatic vessels in the brain. The spatial relationship of glymphatics, including their essential component aquaporin-4 with vascular pericytes of brain arterioles is critical to functionality and is termed "polarization".

MATERIALS AND METHODS

We review the available literature on the factors affecting the resting state of glymphatics under normal conditions, including the important role of sleep in supporting normal glymphatic function (including waste removal) as well as the critical role of "polarization" under normal conditions. We then examine the effects of traumatic brain injury (TBI) or seizures on the glymphatic system and its state of "polarization".

RESULTS

Injury, such as TBI, can disrupt polarization resulting in "depolarization" leading to brain edema.

CONCLUSION

Damage to the glymphatic system might explain the brain edema so often seen following TBI or other insult. Moreover, similar damage should be expected in response to seizures, which can often be associated with chemical exposures as well as with TBI. Military operations, whether night operations or continuous operations, quite often impose limitations on sleep. As glymphatic function is sleep-dependent, sleep deprivation alone could compromise glymphatic function, as well, and might in addition, explain some of the well-known performance deficits associated with sleep deprivation. Possible effects of submarine and diving operations, chemical agents (including seizures), as well as high altitude exposure and other threats should be considered. In addition to the brain, the retina is also served and protected by the glymphatic system. Accordingly, the effect of military-related risks (e.g., exposure to laser or other threats) to retinal glymphatic function should also be considered. An intact glymphatic system is absolutely essential to support normal central nervous system functionality, including cognition. This effects a broad range of military threats on brain and retinal glymphatics should be explored. Possible preventive and therapeutic measures should be proposed and evaluated, as well.

Focus on the Lymphatic Route to Optimize Drug Delivery in Cardiovascular Medicine

While oral agents have been the gold standard for cardiovascular disease therapy, the new generation of treatments is switching to other administration options that offer reduced dosing frequency and more efficacy. The lymphatic network is a unidirectional and low-pressure vascular system that is responsible for the absorption of interstitial fluids, molecules, and cells from the peripheral tissue, including the skin and the intestines. Targeting the lymphatic route for drug delivery employing traditional or new technologies and drug formulations is exponentially gaining attention in the quest to avoid the hepatic first-pass effect. The present review will give an overview of the current knowledge on the involvement of the lymphatic vessels in drug delivery in the context of cardiovascular disease.

Matrix stiffness primes lymphatic tube formation directed by vascular endothelial growth factor-C

Dysfunction of the lymphatic system is associated with a wide range of disease phenotypes. The restoration of dysfunctional lymphatic vessels has been hypothesized as an innovative method to rescue healthy phenotypes in diseased states including neurological conditions, metabolic syndromes, and cardiovascular disease. Compared to the vascular system, little is known about the molecular regulation that controls lymphatic tube morphogenesis. Using synthetic hyaluronic acid (HA) hydrogels as a chemically and mechanically tunable system to preserve lymphatic endothelial cell (LECs) phenotypes, we demonstrate that low matrix elasticity primes lymphatic cord-like structure (CLS) formation directed by a high concentration of vascular endothelial growth factor-C (VEGF-C). Decreasing the substrate stiffness results in the upregulation of key lymphatic markers, including PROX-1, lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), and VEGFR-3. Consequently, higher levels of VEGFR-3 enable stimulation of LECs with VEGF-C which is required to both activate matrix metalloproteinases (MMPs) and facilitate LEC migration. Both of these steps are critical in establishing CLS formation in vitro. With decreases in substrate elasticity, we observe increased MMP expression and increased cellular elongation, as well as formation of intracellular vacuoles, which can further merge into coalescent vacuoles. RNAi studies demonstrate that MMP-14 is required to enable CLS formation and that LECs sense matrix stiffness through YAP/TAZ mechanosensors leading to the activation of their downstream target genes. Collectively, we show that by tuning both the matrix stiffness and VEGF-C concentration, the signaling pathways of CLS formation can be regulated in a synthetic matrix, resulting in lymphatic networks which will be useful for the study of lymphatic biology and future approaches in tissue regeneration.

Fluid metabolic pathways after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating cerebrovascular disease with high mortality and morbidity. In recent years, a large number of studies have focused on the mechanism of early brain injury (EBI) and delayed cerebral ischemia (DCI), including vasospasm, neurotoxicity of hematoma and neuroinflammatory storm, after aSAH. Despite considerable efforts, no novel drugs have significantly improved the prognosis of patients in phase III clinical trials, indicating the need to further re-examine the multifactorial pathophysiological process that occurs after aSAH. The complex pathogenesis is reflected by the destruction of the dynamic balance of the energy metabolism in the nervous system after aSAH, which prevents the maintenance of normal neural function. This review focuses on the fluid metabolic pathways of the central nervous system (CNS), starting with ruptured aneurysms, and discusses the dysfunction of blood circulation, cerebrospinal fluid (CSF) circulation and the glymphatic system during disease progression. It also proposes a hypothesis on the metabolic disorder mechanism and potential therapeutic targets for aSAH patients.

Overcoming physiological barriers by nanoparticles for intravenous drug delivery to the lymph nodes

The lymph nodes are major sites of cancer metastasis and immune activity, and thus represent important clinical targets. Although not as well-studied compared to subcutaneous administration, intravenous drug delivery is advantageous for lymph node delivery as it is commonly practiced in the clinic and has the potential to deliver therapeutics systemically to all lymph nodes. However, rapid clearance by the mononuclear phagocyte system, tight junctions of the blood vascular endothelium, and the collagenous matrix of the interstitium can limit the efficiency of lymph node drug delivery, which has prompted research into the design of nanoparticle-based drug delivery systems. In this mini review, we describe the physiological and biological barriers to lymph node targeting, how they inform nanoparticle design, and discuss the future outlook of lymph node targeting.

Recent advances in combination of microneedles and nanomedicines for lymphatic targeted drug delivery

Numerous diseases have been reported to affect the lymphatic system. As such, several strategies have been developed to deliver chemotherapeutics to this specific network of tissues and associated organs. Nanotechnology has been exploited as one of the main approaches to improve the lymphatic uptake of drugs. Different nanoparticle approaches utilized for both active and passive targeting of the lymphatic system are discussed here. Specifically, due to the rich abundance of lymphatic capillaries in the dermis, particular attention is given to this route of administration, as intradermal administration could potentially result in higher lymphatic uptake compared to other routes of administration. Recently, progress in microneedle research has attracted particular attention as an alternative for the use of conventional hypodermic injections. The benefits of microneedles, when compared to intradermal injection, are subsequently highlighted. Importantly, microneedles exhibit particular benefit in relation to therapeutic targeting of the lymphatic system, especially when combined with nanoparticles, which are further discussed. However, despite the apparent benefits provided by this combination approach, further comprehensive preclinical and clinical studies are now necessary to realize the potential extent of this dual-delivery platform, further taking into consideration eventual usability and acceptability in the intended patient end-users. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Laboratory diagnosis of a new outbreak of acute African swine fever in smallholder pig farms in Jos, Nigeria

African swine fever (ASF) is a highly contagious fatal infectious disease of pigs and wild suids. The disease has a worldwide occurrence and significant impact on pig production. Two adult intensively raised large white boars from two farms in Jos with a history of sudden death were diagnosed of ASF between July and August 2019. Post‐mortem examination of carcasses grossly showed splenomegaly, haemorrhagic lymphadenitis and hepatomegaly with severe congestion. The kidneys were enlarged and had generalized petechiae and blood clot in the pelvis. The heart was moderately enlarged. Microscopic examination of the spleen and lymph nodes revealed severe lymphocytic depletion, haemorrhage and severe haemosiderosis. The liver was severely congested with focal coagulative necrosis of the hepatocytes. The kidneys were severely congested and showed renal tubular necrosis with few tubular protein casts. Tissue samples were confirmed to be positive for African swine fever virus (ASFV) by polymerase chain reaction (PCR) assay, and phylogenetic analysis revealed that the isolate belonged to genotype I.

Ras Pathways on Prox1 and Lymphangiogenesis: Insights for Therapeutics

Over the past couple of decades, lymphatics research has accelerated and gained a much-needed recognition in pathophysiology. As the lymphatic system plays heavy roles in interstitial fluid drainage, immune surveillance and lipid absorption, the ablation or excessive growth of this vasculature could be associated with many complications, from lymphedema to metastasis. Despite their growing importance in cancer, few anti-lymphangiogenic therapies exist today, as they have yet to pass phase 3 clinical trials and acquire FDA approval. As such, many studies are being done to better define the signaling pathways that govern lymphangiogenesis, in hopes of developing new therapeutic approaches to inhibit or stimulate this process. This review will cover our current understanding of the Ras signaling pathways and their interactions with Prox1, the master transcriptional switch involved in specifying lymphatic endothelial cell fate and lymphangiogenesis, in hopes of providing insights to lymphangiogenesis-based therapies.

Astrocytes, HIV and the Glymphatic System: A Disease of Disrupted Waste Management?

The discovery of the glial-lymphatic or glymphatic fluid clearance pathway in the rodent brain led researchers to search for a parallel system in humans and to question the implications of this pathway in neurodegenerative diseases. Magnetic resonance imaging studies revealed that several features of the glymphatic system may be present in humans. In both rodents and humans, this pathway promotes the exchange of interstitial fluid (ISF) and cerebrospinal fluid (CSF) through the arterial perivascular spaces into the brain parenchyma. This process is facilitated in part by aquaporin-4 (AQP4) water channels located primarily on astrocytic end feet that abut cerebral endothelial cells of the blood brain barrier. Decreased expression or mislocalization of AQP4 from astrocytic end feet results in decreased interstitial flow, thereby, promoting accumulation of extracellular waste products like hyperphosphorylated Tau (pTau). Accumulation of pTau is a neuropathological hallmark in Alzheimer's disease (AD) and is accompanied by mislocalization of APQ4 from astrocyte end feet to the cell body. HIV infection shares many neuropathological characteristics with AD. Similar to AD, HIV infection of the CNS contributes to abnormal aging with altered AQP4 localization, accumulation of pTau and chronic neuroinflammation. Up to 30% of people with HIV (PWH) suffer from HIV-associated neurocognitive disorders (HAND), and changes in AQP4 may be clinically important as a contributor to cognitive disturbances. In this review, we provide an overview and discussion of the potential contributions of NeuroHIV to glymphatic system functions by focusing on astrocytes and AQP4. Although HAND encompasses a wide range of neurocognitive impairments and levels of neuroinflammation vary among and within PWH, the potential contribution of disruption in AQP4 may be clinically important in some cases. In this review we discuss implications for possible AQP4 disruption on NeuroHIV disease trajectory and how HIV may influence AQP4 function.

3D Immunocompetent Organ-on-a-Chip Models

In recent years, engineering of various human tissues in microphysiologically relevant platforms, known as organs-on-chips (OOCs), has been explored to establish in vitro tissue models that recapitulate the microenvironments found in native organs and tissues. However, most of these models have overlooked the important roles of immune cells in maintaining tissue homeostasis under physiological conditions and in modulating the tissue microenvironments during pathophysiology. Significantly, gradual progress is being made in the development of more sophisticated microphysiologically relevant human-based OOC models that allow the studies of the key biophysiological aspects of specific tissues or organs, interactions between cells (parenchymal, vascular, and immune cells) and their extracellular matrix molecules, effects of native tissue architectures (geometry, dynamic flow or mechanical forces) on tissue functions, as well as unravelling the mechanism underlying tissue-specific diseases and drug testing. In this Progress Report, we discuss the different components of the immune system, as well as immune OOC platforms and immunocompetent OOC approaches that have simulated one or more components of the immune system. We also outline the challenges to recreate a fully functional tissue system in vitro with a focus on the incorporation of the immune system.

Prolonging the Half-Life of Histone Deacetylase Inhibitor Belinostat via 50 nm Scale Liposomal Subcutaneous Delivery System for Peripheral T-Cell Lymphoma

Simple Summary

Belinostat is the novel histone deacetylase inhibitors (HDACis) for treatment for peripheral T-cell lymphoma (PTCL). However, the half-life of belinostat is only 1.1 h. The aim of the study was to improve the half-life and it’s in vivo circulation behavior by using liposome encapsulation technology. The 50 nm scale liposomes were prepared, which showed the sustained release behavior, decrease the burst effect and improving the drug’s toxicity and had similar power for HuT-78 cells. Moreover, we proposed that phospholipid types are crucial factors for size forming and in vivo circulation behavior. We found that DOPC phospholipid material increased the half-life of belinostat, decreased clearance and presented a higher area under curve exposure. Due to the lymphatic delivery complexation, the localized at the lymphatic organs study is necessary to evaluate in the near future.

Abstract

Lymph node metastasis is an aggressive condition characterized by poor treatment outcomes and low overall survival. Belinostat is a novel histone deacetylase (HDAC) inhibitor approved by the Food and Drug Administration (FDA) for the treatment of relapsed peripheral T-cell lymphoma (PTCL). However, the major problem is that belinostat has a short half-life of 1.1 h. In this study, we successfully prepared 50 nm liposomal colloids, which showed a controlled release pattern and excellent pharmacokinetics. The results showed that the particle size of liposomes consisting of dioleoylphosphatidylcholine (DOPC) was larger than that of those consisting of dioleoylglycerophosphoserine (DOPS). In terms of release kinetics of belinostat, the free drug was rapidly released and showed lower area under curve (AUC) exposure for in vivo pharmacokinetics. When liposomal formulations were employed, the release pattern was fitted with Hixson–Crowell models and showed sustained release of belinostat. Moreover, HuT-78 cells were able to take up all the liposomes in a concentration-dependent manner. The safety assessment confirmed hemocompatibility, and the platelet count was increased. Furthermore, the liposomes consisting of DOPC or DOPS had different behavior patterns, and their delivery to lymphatic regions should be thoroughly investigated in the future.

Effect of VEGFC on lymph flow and inflammation-induced alveolar bone loss

The lymphatic system plays a crucial role in the maintenance of tissue fluid homeostasis and the immunological response to inflammation. The effects of lymphatic drainage dysfunction on periodontitis have not been well studied. Here we show that lymphatic vessel endothelial receptor 1 (LYVE1)+ /podoplanin (PDPN)+ lymphatic vessels (LVs) are increased in the periodontal tissues, with accumulation close to the alveolar bone surface, in two murine periodontitis models: rheumatoid arthritis (RA)-associated periodontitis and ligature-induced periodontitis. Further, PDPN+ /alpha-smooth muscle actin (αSMA)- lymphatic capillaries are increased, whereas PDPN+ /αSMA+ collecting LVs are decreased significantly in the inflamed periodontal tissues. Both mouse models of periodontitis have delayed lymph flow in periodontal tissues, increased TRAP-positive osteoclasts, and significant alveolar bone loss. Importantly, the local administration of adeno-associated virus for vascular endothelial growth factor C, the major growth factor that promotes lymphangiogenesis, increases the area and number of PDPN+ /αSMA+ collecting LVs, promotes local lymphatic drainage, and reduces alveolar bone loss in both models of periodontitis. Lastly, LYVE1+ /αSMA- lymphatic capillaries are increased, whereas LYVE1+ /αSMA+ collecting LVs are decreased significantly in gingival tissues of patients with chronic periodontitis compared with those of clinically healthy controls. Thus, our findings reveal an important role of local lymphatic drainage in periodontal inflammation-mediated alveolar bone loss. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Microenvironment-Dependent Gradient of CTL Exhaustion in the AE17sOVA Murine Mesothelioma Tumor Model

The immune system, and in particular, cytotoxic CD8⁺ T cells (CTLs), plays a vital part in the prevention and elimination of tumors. In many patients, however, CTL-mediated tumor killing ultimately fails in the clearance of cancer cells resulting in disease progression, in large part due to the progression of effector CTL into exhausted CTL. While there have been major breakthroughs in the development of CTL-mediated “reinvigoration”-driven immunotherapies such as checkpoint blockade therapy, there remains a need to better understand the drivers behind the development of T cell exhaustion. Our study highlights the unique differences in T cell exhaustion development in tumor-specific CTL which arises over time in a mouse model of mesothelioma. Importantly, we also show that peripheral tumor-specific T cells have a unique expression profile compared to exhausted tumor-infiltrating CTL at a late-stage of tumor progression in mice. Together, these data suggest that greater emphasis should be placed on understanding contributions of individual microenvironments in the development of T cell exhaustion.

Activation of the VEGFC/VEGFR3 Pathway Induces Tumor Immune Escape in Colorectal Cancer

Colorectal cancer is a major cause of cancer-related death in Western countries and is associated with increased numbers of lymphatic vessels (LV) and tumor-associated macrophages (TAM). The VEGFC/VEGFR3 pathway is regarded as the principal inducer of lymphangiogenesis and it contributes to metastases; however, no data are available regarding its role during primary colorectal cancer development. We found that both VEGFC and VEGFR3 were upregulated in human nonmetastatic colorectal cancer, with VEGFR3 expressed on both LVs and TAMs. With the use of three different preclinical models of colorectal cancer, we also discovered that the VEGFC/VEGFR3 axis can shape both lymphatic endothelial cells and TAMs to synergistically inhibit antitumor immunity and promote primary colorectal cancer growth. Therefore, VEGFR3-directed therapy could be envisioned for the treatment of nonmetastatic colorectal cancer. SIGNIFICANCE: The prolymphangiogenic factor VEGFC is abundant in colorectal cancer and activates VEGFR3 present on cancer-associated macrophages and lymphatic vessels; activation of VEGFR3 signaling fosters cancer immune escape, resulting in enhanced tumor growth.

Call for a Multidisciplinary Effort to Map the Lymphatic System with Advanced Medical Imaging Techniques: A Review of the Literature and Suggestions for Future Anatomical Research

This review intends to rekindle efforts to map the lymphatic system by using a more modern approach, based on medical imaging. The structure, function, and pathologies associated with the lymphatic system are first discussed to highlight the need for more accurately mapping the lymphatic system. Next, the need for an interdisciplinary approach, with a central role for the anatomist, to come up with better maps of the lymphatic system is emphasized. The current approaches on lymphatic system research involving medical imaging will be discussed and suggestions will be made for an all-encompassing effort to thoroughly map the entire lymphatic system. A first-hand account of our integration as anatomists in the radiotherapy department is given as an example of interdisciplinary collaboration. From this account, it will become clear that the interdisciplinary collaboration of anatomists in the clinical disciplines involved in lymphatic system research/treatment still holds great promise in terms of improving clinical regimens that are currently being employed. As such, we hope that our fellow anatomists will join us in an interdisciplinary effort to map the lymphatic system, because this could, in a relatively short timeframe, provide improved treatment options for patients with cancer or lymphatic pathologies all over the world. Anat Rec, 302:1681-1695, 2019. © 2019 American Association for Anatomy.

Application of microscale culture technologies for studying lymphatic vessel biology

Immense progress in microscale engineering technologies has significantly expanded the capabilities of in vitro cell culture systems for reconstituting physiological microenvironments that are mediated by biomolecular gradients, fluid transport, and mechanical forces. Here, we examine the innovative approaches based on microfabricated vessels for studying lymphatic biology. To help understand the necessary design requirements for microfluidic models, we first summarize lymphatic vessel structure and function. Next, we provide an overview of the molecular and biomechanical mediators of lymphatic vessel function. Then we discuss the past achievements and new opportunities for microfluidic culture models to a broad range of applications pertaining to lymphatic vessel physiology. We emphasize the unique attributes of microfluidic systems that enable the recapitulation of multiple physicochemical cues in vitro for studying lymphatic pathophysiology. Current challenges and future outlooks of microscale technology for studying lymphatics are also discussed. Collectively, we make the assertion that further progress in the development of microscale models will continue to enrich our mechanistic understanding of lymphatic biology and physiology to help realize the promise of the lymphatic vasculature as a therapeutic target for a broad spectrum of diseases.

Extracellular RNA Profile in Mesenteric Lymph from Exemplar Rat Models of Acute and Critical Illness

Background: Mesenteric lymph (ML) has been implicated in the development of multiple organ dysfunction syndrome in critical illness. Extracellular RNAs play a role in cell-to-cell communication during physiological and disease processes but they are rarely studied in ML. We aimed at examining the RNA profiles of peripheral plasma, ML, and ML's extracellular vesicle (ML-EV) and triglyceride-rich lipoprotein (ML-TRL) fractions, obtained from rodent models of critical illness. Methods and Results: We collected ML for 5 hours from rodent models of critical illness [Acute Pancreatitis, Cecal Ligation and Incision (CLI), Gut Ischemia-Reperfusion (IR)] and matching Sham control rats. ML-EV and ML-TRL fractions were also isolated. RNA sequencing was performed on the RNA extracted from ML, ML-EV, ML-TRL, and plasma by using the Ion Torrent Personal Genome Machine platform. RNA sequences were searched using the Basic Local Alignment Search Tool against rat genome and RefSeq, microRNA (miRNA), genomic tRNA, functional RNA, and Genbank nucleotide databases, and the read counts were analyzed. Each sample type had a distinct RNA profile. ML contained more RNA per volume and a larger proportion of tRNA fragments than plasma. ML-EVs were enriched with miRNA, whereas ML-TRLs contained low absolute amounts of RNA. The RNA size profiles for CLI and Gut IR were different from Sham. ML carried intestinal RNAs and in a CLI model it was significantly enriched with bacterial RNA sequences. Conclusions: We found the distinct but diverse RNA profiles of ML and its compartments, and their different profiles in critical illness. Intestinal-derived small RNAs in ML may have a direct role in critical illness and utility as potential biomarkers.