Lymphatic endothelial cells regulate B-cell homing to lymph nodes via a NIK-dependent mechanism

NIK Is a Mediator of Inflammation and Intimal Hyperplasia in Endothelial Denudation-Induced Vascular Injury

Neointimal hyperplasia is the main cause of vascular graft failure in the medium term. NFκB is a key mediator of inflammation that is activated during neointimal hyperplasia following endothelial injury. However, the molecular mechanisms involved in NFκB activation are poorly understood. NFκB may be activated through canonical (transient) and non-canonical (persistent) pathways. NFκB-inducing kinase (NIK, MAP3K14) is the upstream kinase of the non-canonical pathway. We have now explored the impact of NIK deficiency on neointimal hyperplasia following guidewire-induced endothelial cell injury and on local inflammation by comparing NIK activity-deficient alymphoplasia mice (NIKaly/aly) with control wild-type (NIK+/+) mice. Guidewire-induced endothelial cell injury caused neointimal hyperplasia and luminal stenosis and upregulated the local expression of NIK and the NFκB target chemokines monocyte chemoattractant protein-1 (MCP-1/CCL2) and chemokine ligand 5 (RANTES/CCL5). Immunohistochemistry disclosed the infiltration of the media and intima by F4/80 positive macrophages. The intima/media ratio and percentage of stenosis were milder in the NIKaly/aly than in the NIK+/+ mice. Additionally, the gene expression for MCP-1 and RANTES was lower and F4/80+ cell infiltration was milder in the NIKaly/aly than in the NIK+/+ mice. Finally, circulating MCP-1 levels were lower in the NIKaly/aly than in the NIK+/+ mice, reflecting milder systemic inflammation. In conclusion, NIK is a driver of vascular wall inflammation and stenosis following guidewire-induced endothelial cell injury. NIK targeting may be a novel therapeutic approach to limit arterial stenosis following endothelial cell injury.

The development of a human Brucella mucosal vaccine: What should be considered?

Brucellosis is a chronic infectious disease that is zoonotic in nature. Brucella can infect humans through interactions with livestock, primarily via the digestive tract, respiratory tract, and oral cavity. This bacterium has the potential to be utilized as a biological weapon and is classified as a Category B pathogen by the Centers for Disease Control and Prevention. Currently, there is no approved vaccine for humans against Brucella, highlighting an urgent need for the development of a vaccine to mitigate the risks posed by this pathogen. Brucella primarily infects its host by adhering to and penetrating mucosal surfaces. Mucosal immunity plays a vital role in preventing local infections, clearing microorganisms from mucosal surfaces, and inhibiting the spread of pathogens. As mucosal vaccine strategies continue to evolve, the development of a safe and effective mucosal vaccine against Brucella appears promising.This paper reviews the immune mechanism of mucosal vaccines, the infection mechanism of Brucella, successful Brucella mucosal vaccines in animals, and mucosal adjuvants. Additionally, it elucidates targeting and optimization strategies for mucosal vaccines to facilitate the development of human vaccines against Brucella.

ANKRD22 promotes resolution of psoriasiform skin inflammation by antagonizing NIK-mediated IL-23 production

Inflammation resolution is an essential process for preventing the development of chronic inflammatory diseases. However, the mechanisms that regulate inflammation resolution in psoriasis are not well understood. Here, we report that ANKRD22 is an endogenous negative orchestrator of psoriasiform inflammation because ANKRD22-deficient mice are more susceptible to IMQ-induced psoriasiform inflammation. Mechanistically, ANKRD22 deficiency leads to excessive activation of the TNFRII-NIK-mediated noncanonical NF-κB signaling pathway, resulting in the hyperproduction of IL-23 in DCs. This is due to ANKRD22 being a negative feedback regulator for NIK because it physically binds to and assists in the degradation of accumulated NIK. Clinically, ANKRD22 is negatively associated with IL-23A expression and psoriasis severity. Of greater significance, subcutaneous administration of an AAV carrying ANKRD22-overexpression vector effectively hastens the resolution of psoriasiform skin inflammation. Our findings suggest ANKRD22, an endogenous supervisor of NIK, is responsible for inflammation resolution in psoriasis, and may be explored in the context of psoriasis therapy.

Tree of life: endothelial cell in norm and disease, the good guy is a partner in crime!

Undeniably, endothelial cells (EC) contribute to the maintenance of the homeostasis of the organism through modulating cellular physiology, including signaling pathways, through the release of highly active molecules as well as the response to a myriad of extrinsic and intrinsic signaling factors. Review the data from the current literature on the EC role in norm and disease. Endothelium maintains a precise balance between the released molecules, where EC dysfunction arises when the endothelium actions shift toward vasoconstriction, the proinflammatory, prothrombic properties after the alteration of nitric oxide (NO) production and oxidative stress. The functions of the EC are regulated by the negative/positive feedback from the organism, through EC surface receptors, and the crosstalk between NO, adrenergic receptors, and oxidative stress. More than a hundred substances can interact with EC. The EC dysfunction is a hallmark in the emergence and progression of vascular-related pathologies. The paper concisely reviews recent advances in EC (patho) physiology. Grasping EC physiology is crucial to gauge their potential clinical utility and optimize the current therapies as well as to establish novel nanotherapeutic molecular targets include; endothelial receptors, cell adhesion molecules, integrins, signaling pathways, enzymes; peptidases.

Endothelial cell autophagy in the context of disease development

Endothelial cells (EC) are the anatomical boundaries between the intravascular and extravascular space. Damage to ECs is catastrophic and induces endothelial cell dysfunction. The pathogenesis is multifactorial and involves dysregulation in the signaling pathways, membrane lipids ratio disturbance, cell-cell adhesion disturbance, unfolded protein response, lysosomal and mitochondrial stress, autophagy dysregulation, and oxidative stress. Autophagy is a lysosomal-dependent turnover of intracellular components. Autophagy was recognized early in the pathogenesis of endothelial dysfunction. Autophagy is a remarkable patho (physiological) process in the cell homeostasis regulation including EC. Regulation of autophagy rate is disease-dependent and impaired with aging. Up-regulation of autophagy induces endothelial cell regeneration/differentiation and improves the function of impaired ones. The paper scrutinizes the molecular mechanisms and triggers of EC dysregulation and current perspectives for future therapeutic strategies by autophagy targeting.

Nuclear factor-kappa B and effector molecules in photoaging

Nuclear factor-kappa B (NF-κB) has important but complex functions in the photoaging of the human skin. This protein complex is activated upon UV irradiation and plays a key role in the signalling pathway of the inflammatory cascade. NF-κB induces the expression of various proinflammatory cytokines, such as tumour necrosis factor (TNF) and interleukin-1 (IL-1). These proinflammatory cytokines can in turn stimulate the activation of NF-κB, forming a vicious cycle. These processes cause chronic inflammation and contribute to skin ageing. In addition, the activation of NF-κB upregulates the expression of matrix metalloproteinases (MMPs) and leads to the degradation of structural proteins in the dermis. NF-κB disrupts the barrier function of the skin under prolonged and repeated UV stimulations in these ways. Such activity causes chronic skin damage, followed by the formation of wrinkles, dryness, roughness, laxity, and other photoaging manifestations. This study on the NF-κB signalling pathway and effector molecules provides a new perspective to understand and prevent photoaging.

Lymph node formation and B cell homeostasis require IKK-α in distinct endothelial cell-derived compartments

Global inactivation of IκB kinase (IKK)-α results in defective lymph node (LN) formation and B cell maturation, and loss of IKK-α-dependent noncanonical NF-κB signaling in stromal organizer and hematopoietic cells is thought to underlie these distinct defects. We previously demonstrated that this pathway is also activated in vascular endothelial cells (ECs). To determine the physiologic function of EC-intrinsic IKK-α, we crossed Ikkα^F/F mice with Tie2-cre or Cdh5-cre mice to ablate IKK-α in ECs. Notably, the compound defects of global IKK-α inactivation were recapitulated in Ikkα^Tie2 and Ikkα^Cdh5 mice, as both lacked all LNs and mature follicular and marginal zone B cell numbers were markedly reduced. However, as Tie2-cre and Cdh5-cre are expressed in all ECs, including blood forming hemogenic ECs, IKK-α was also absent in hematopoietic cells (HC). To determine if loss of HC-intrinsic IKK-α affected LN development, we generated Ikkα^Vav mice lacking IKK-α in only the hematopoietic compartment. While mature B cell numbers were significantly reduced in Ikkα^Vav mice, LN formation was intact. As lymphatic vessels also arise during development from blood ECs, we generated Ikkα^Lyve1 mice lacking IKK-α in lymphatic ECs (LECs) to determine if IKK-α in lymphatic vessels impacts LN development. Strikingly, while mature B cell numbers were normal, LNs were completely absent in Ikkα^Lyve1 mice. Thus, our findings reveal that IKK-α in distinct EC-derived compartments is uniquely required to promote B cell homeostasis and LN development, and we establish that LEC-intrinsic IKK-α is absolutely essential for LN formation.

Relationship between Tertiary Lymphoid Structure and the Prognosis and Clinicopathologic Characteristics in Solid Tumors

Background: An increasing number of studies had shown that tertiary lymphoid structure (TLS) plays an important role in tumor progression. However, the prognostic role of TLS in various tumors remains controversial. This meta-analysis aims to investigate the clinicopathological and prognostic values of TLS in solid tumors. Methods: A systematic search was conducted in PubMed, EMBASE and Cochrane Library undated to November 2, 2020. Odds ratios of clinical parameters, hazard ratio (HR) of overall survival (OS), relapse-free survival (RFS), disease-free survival (DFS) and relapse rate were calculated in order to evaluate the relationship between TLS expression and clinicopathological or prognostic values in different tumors. Result: 27 eligible studies including 6647 patients with different types of tumors were analyzed. High TLS expression was associated with a longer OS (HR = 0.66, 95% CI: 0.50 - 0.86, P = 0.002) and RFS (HR = 0.61, 95% CI: 0.47 - 0.79, P = 0.0001). Moreover, high TLS levels in tumor were associated with a low risk of recurrence (HR = 0.43, 95% CI: 0.32 - 0.57, P < 0.0001). However, there was no relationship between TLS expression and DFS. Meanwhile, high TLS expression was associated with smaller tumor size (P < 0.00001) and higher tumor infiltrating lymphocytes (TILs). Furthermore, the subgroup analysis showed high TLS expression that may be associated with a lower clinical grading and N stage in breast cancer and colorectal cancer. Conclusion: High TLS expression is associated with the longer OS and RFS in solid tumors, and a lower risk of cancer relapse. Meanwhile, high TLS expression is also associated with a smaller tumor size, higher infiltration of TILs, lower clinical grading and N stage in the tumor. Therefore, high TLS expression in the tumor is a favorable prognostic biomarker for solid tumor patients.

LTβR Signaling Controls Lymphatic Migration of Immune Cells

The pleiotropic functions of lymphotoxin (LT)β receptor (LTβR) signaling are linked to the control of secondary lymphoid organ development and structural maintenance, inflammatory or autoimmune disorders, and carcinogenesis. Recently, LTβR signaling in endothelial cells has been revealed to regulate immune cell migration. Signaling through LTβR is comprised of both the canonical and non-canonical-nuclear factor κB (NF-κB) pathways, which induce chemokines, cytokines, and cell adhesion molecules. Here, we focus on the novel functions of LTβR signaling in lymphatic endothelial cells for migration of regulatory T cells (Tregs), and specific targeting of LTβR signaling for potential therapeutics in transplantation and cancer patient survival.

Stromal regulation of tumor-associated lymphatics

Recent advances have identified a growing array of roles played by lymphatics in the tumor microenvironment, from providing a route of metastasis to immune modulation. The tumor microenvironment represents an exceptionally complex, dynamic niche comprised of a diverse mixture of cancer cells and normal host cells termed the stroma. This review discusses our current understanding of stromal elements and how they regulate lymphatic growth and functional properties in the tumor context.

The Role of Endothelial Cells and TNF-Receptor Superfamily Members in Lymphoid Organogenesis and Function During Health and Inflammation

Lymph nodes (LNs) are crucial for the orchestration of immune responses. LN reactions depend on interactions between incoming and local immune cells, and stromal cells. To mediate these cellular interactions an organized vascular network within the LN exists. In general, the LN vasculature can be divided into two components: blood vessels, which include the specialized high endothelial venules that recruit lymphocytes from the bloodstream, and lymphatic vessels. Signaling via TNF receptor (R) superfamily (SF) members has been implicated as crucial for the development and function of LNs and the LN vasculature. In recent years the role of cell-specific signaling of TNFRSF members in different endothelial cell (EC) subsets and their roles in development and maintenance of lymphoid organs has been elucidated. Here, we discuss recent insights into EC-specific TNFRSF member signaling and highlight its importance in different EC subsets in LN organogenesis and function during health, and in lymphocyte activation and tertiary lymphoid structure formation during inflammation.

Conditional Activation of NF-κB Inducing Kinase (NIK) in the Osteolineage Enhances Both Basal and Loading-Induced Bone Formation

Studies from global loss-of-function mutants suggest that alternative NF-κB downstream of NF-κB inducing kinase (NIK) is a cell-intrinsic negative regulator of osteogenesis. However, the interpretation of the osteoblast and/or osteocyte contribution to the bone phenotype is complicated by simultaneous osteoclast defects in these models. Therefore, we turned to a transgenic mouse model to investigate the direct role of NIK in the osteolineage. Osx-Cre;NT3 animals (NT3-Cre +), which bear a constitutively active NIK allele (NT3) driven by Osx-Cre, were compared with their Cre-negative, Control (Ctrl) littermates. NT3-Cre + mice had elevated serum P1NP and CTX levels. Despite this high turnover state, µCT showed that constitutive activation of NIK resulted in a net increase in basal bone mass in both cortical and cancellous compartments. Furthermore, NT3-Cre + mice exhibited a greater anabolic response following mechanical loading compared with controls. We next performed RNA-Seq on nonloaded and loaded tibias to elucidate possible mechanisms underlying the increased bone anabolism seen in NT3-Cre + mice. Hierarchical clustering revealed two main transcriptional programs: one loading-responsive and the other NT3 transgene-driven. Gene ontology (GO) analysis indicated a distinct upregulation of receptor, kinase, and growth factor activities including Wnts, as well as a calcium-response signature in NT3-Cre + limbs. The promoters of these GO-term associated genes, including many known to be bone-anabolic, were highly enriched for multiple κB recognition elements (κB-RE) relative to the background frequency in the genome. The loading response in NT3-Cre + mice substantially overlapped (>90%) with Ctrl. Surprisingly, control animals had 10-fold more DEGs in response to loading. However, most top DEGs shared between genotypes had a high incidence of multiple κB-RE in their promoters. Therefore, both transcriptional programs (loading-responsive and NT3 transgene-driven) are modulated by NF-κB. Our studies uncover a previously unrecognized role for NF-κB in the promotion of both basal and mechanically stimulated bone formation. © 2019 American Society for Bone and Mineral Research.

A Dual Targeting Magnetic Nanoparticle for Human Cancer Detection

Malignant tumors are a major threat to human life and high lymphatic vessel density is often associated with metastatic tumors. With the discovery of molecules targeted at the lymphatic system such as lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1) and Podoplanin, many studies have been performed to determine the role of lymphatic endothelial cells (LECs) in tumor metastasis. However, disadvantages such as non-specificity and high cost limit their research and diagnostic applications. In this study, Fe₃O₄@KCTS, a core-shell type of magnetic nanoparticles, was prepared by activating Fe₃O₄ with carbodiimide and cross-linking it with α-ketoglutarate chitosan (KCTS). The LYVE-1 and Podoplanin antibodies were then incorporated onto the surface of these magnetic nanoparticles and as a result, dual-targeting magnetic nanoprobes were developed. The experimental tests of this study demonstrated that a dual-targeting magnetic nanoprobe with high-purity LECs from tumor tissues was successfully developed, providing a basis for clinical application of LECs in colorectal cancer treatment as well as in early clinical diagnosis using bimodal imaging.

NIK as a Druggable Mediator of Tissue Injury

NF-κB-inducing kinase (NIK, MAP3K14) is best known as the apical kinase that triggers non-canonical NF-κB activation and by its role in the immune system. Recent data indicate a role for NIK expressed by non-lymphoid cells in cancer, kidney disease, liver injury, glucose homeostasis, osteosarcopenia, vascular calcification, hematopoiesis, and endothelial function. The spectrum of NIK-associated disease now ranges from immunodeficiency (when NIK is defective) to autoimmunity, cancer, sterile inflammation, fibrosis, and metabolic disease when NIK is overactive. The development of novel small-molecule NIK inhibitors has paved the way to test NIK targeting to treat disease in vivo, and may eventually lead to NIK targeting in the clinic. In addition, NIK activators are being explored for specific conditions such as myeloid leukemia.

Comparative Transcriptomic Analysis Identifies a Range of Immunologically Related Functional Elaborations of Lymph Node Associated Lymphatic and Blood Endothelial Cells

Lymphatic and blood vessels are formed by specialized lymphatic endothelial cells (LEC) and blood endothelial cells (BEC), respectively. These endothelial populations not only form peripheral tissue vessels, but also critical supporting structures in secondary lymphoid organs, particularly the lymph node (LN). Lymph node LEC (LN-LEC) also have been shown to have important immunological functions that are not observed in LEC from tissue lymphatics. LN-LEC can maintain peripheral tolerance through direct presentation of self-antigen via MHC-I, leading to CD8 T cell deletion; and through transfer of self-antigen to dendritic cells for presentation via MHC-II, resulting in CD4 T cell anergy. LN-LEC also can capture and archive foreign antigens, transferring them to dendritic cells for maintenance of memory CD8 T cells. The molecular basis for these functional elaborations in LN-LEC remain largely unexplored, and it is also unclear whether blood endothelial cells in LN (LN-BEC) might express similar enhanced immunologic functionality. Here, we used RNA-Seq to compare the transcriptomic profiles of freshly isolated murine LEC and BEC from LN with one another and with freshly isolated LEC from the periphery (diaphragm). We show that LN-LEC, LN-BEC, and diaphragm LEC (D-LEC) are transcriptionally distinct from one another, demonstrating both lineage and tissue-specific functional specializations. Surprisingly, tissue microenvironment differences in gene expression profiles were more numerous than those determined by endothelial cell lineage specification. In this regard, both LN-localized endothelial cell populations show a variety of functional elaborations that suggest how they may function as antigen presenting cells, and also point to as yet unexplored roles in both positive and negative regulation of innate and adaptive immune responses. The present work has defined in depth gene expression differences that point to functional specializations of endothelial cell populations in different anatomical locations, but especially the LN. Beyond the analyses provided here, these data are a resource for future work to uncover mechanisms of endothelial cell functionality.