A chemokine expressed in lymphoid high endothelial venules promotes the adhesion and chemotaxis of naive T lymphocytes

Dendritic Cell Immune Modulation via Polyphenol Membrane Coatings

Cellular hitchhiking is an emerging strategy for the in vivo control of adoptively transferred immune cells. Hitchhiking approaches are primarily mediated by adhesion of nano and microparticles to the cell membrane, which conveys an ability to modulate transferred cells via local drug delivery. Although T cell therapies employing this strategy have progressed into the clinic, phagocytic cells including dendritic cells (DCs) are much more challenging to engineer. DC vaccines hold great potential for a spectrum of diseases, and the combination drug delivery is an attractive strategy to manipulate their function and overcome in vivo plasticity. However, DCs are not compatible with current hitchhiking approaches due to their broad phagocytic capacity. In this work, we developed and validated META (membrane engineering using tannic acid) to enable DC cellular hitchhiking for the first time. META employs the polyphenol tannic acid (TA) to facilitate supramolecular assembly of protein drug cargoes on the cell membrane, enabling the creation of cell surface-bound formulations for local drug delivery to carrier DCs. We optimized META formulations to incorporate and release protein cargoes with varying physical properties alone and in combination and to preserve DC viability and critical functions such as migration. We further show that META loaded with either a pro- or anti-inflammatory cargo can influence the carrier cell phenotype, thus demonstrating the flexibility of the approach for applications from cancer to autoimmune disease. Overall, this approach illustrates a new platform for the local control of phagocytic immune cells as a next step to advance DC therapies in the clinic.

Epstein-Barr Virus Orchestrates Spatial Reorganization and Immunomodulation within the Classic Hodgkin Lymphoma Tumor Microenvironment

Classic Hodgkin Lymphoma (cHL) is a tumor composed of rare malignant Hodgkin and Reed-Sternberg (HRS) cells nested within a T-cell rich inflammatory immune infiltrate. cHL is associated with Epstein-Barr Virus (EBV) in 25% of cases. The specific contributions of EBV to the pathogenesis of cHL remain largely unknown, in part due to technical barriers in dissecting the tumor microenvironment (TME) in high detail. Herein, we applied multiplexed ion beam imaging (MIBI) spatial pro-teomics on 6 EBV-positive and 14 EBV-negative cHL samples. We identify key TME features that distinguish between EBV-positive and EBV-negative cHL, including the relative predominance of memory CD8 T cells and increased T-cell dysfunction as a function of spatial proximity to HRS cells. Building upon a larger multi-institutional cohort of 22 EBV-positive and 24 EBV-negative cHL samples, we orthogonally validated our findings through a spatial multi-omics approach, coupling whole transcriptome capture with antibody-defined cell types for tu-mor and T-cell populations within the cHL TME. We delineate contrasting transcriptomic immunological signatures between EBV-positive and EBV-negative cases that differently impact HRS cell proliferation, tumor-immune interactions, and mecha-nisms of T-cell dysregulation and dysfunction. Our multi-modal framework enabled a comprehensive dissection of EBV-linked reorganization and immune evasion within the cHL TME, and highlighted the need to elucidate the cellular and molecular fac-tors of virus-associated tumors, with potential for targeted therapeutic strategies.

Microengineered In Vitro Assays for Screening and Sorting Manufactured Therapeutic T Cells

Adoptively transferred T cells constitute a major class of current and emergent cellular immunotherapies for the treatment of disease, including but not limited to cancer. Although key advancements in molecular recognition, genetic engineering, and manufacturing have dramatically enhanced their translational potential, therapeutic potency remains limited by poor homing and infiltration of transferred cells within target host tissues. In vitro microengineered homing assays with precise control over micromechanical and biological cues can address these shortcomings by enabling interrogation, screening, sorting, and optimization of therapeutic T cells based on their homing capacity. In this article, the working principles, application, and integration of microengineered homing assays for the mechanistic study of biophysical and biomolecular cues relevant to homing of therapeutic T cells are reviewed. The potential for these platforms to enable scalable enrichment and screening of next-generation manufactured T cell therapies for cancer is also discussed.

CCL21-Ser expression in melanoma cells recruits CCR7+ naïve T cells to tumor tissues and promotes tumor growth

CCL21-Ser, a chemokine encoded by the Ccl21a gene, is constitutively expressed in the thymic epithelial cells and stromal cells of secondary lymphoid organs. It regulates immune cell migration and survival through its receptor CCR7. Herein, using CCL21-Ser-expressing melanoma cells and the Ccl21a-deficient mice, we demonstrated the functional role of cancer cell-derived CCL21-Ser in melanoma growth in vivo. The B16-F10 tumor growth was significantly decreased in Ccl21a-deficient mice compared with that in wild-type mice, indicating that host-derived CCL21-Ser contributes to melanoma proliferation in vivo. In Ccl21a-deficient mice, tumor growth of melanoma cells expressing CCL21-Ser was significantly enhanced, suggesting that CCL21-Ser from melanoma cells promotes tumor growth in the absence of host-derived CCL21-Ser. The increase in tumor growth was associated with an increase in the CCR7+ CD62L+ T cell frequency in the tumor tissue but was inversely correlated with Treg frequency, suggesting that naïve T cells primarily promote tumor growth. Adoptive transfer experiments demonstrated that naïve T cells are preferentially recruited from the blood into tumors with melanoma cell-derived CCL21-Ser expression. These results suggest that CCL21-Ser from melanoma cells promotes the infiltration of CCR7+ naïve T cells into the tumor tissues and creates a tumor microenvironment favorable for melanoma growth.

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.

The lymphatic vasculature in lung function and respiratory disease

The lymphatic vasculature maintains tissue homeostasis via fluid drainage in the form of lymph and immune surveillance due to migration of leukocytes through the lymphatics to the draining lymph nodes. Lymphatic endothelial cells (LECs) form the lymphatic vessels and lymph node sinuses and are key players in shaping immune responses and tolerance. In the healthy lung, the vast majority of lymphatic vessels are found along the bronchovascular structures, in the interlobular septa, and in the subpleural space. Previous studies in both mice and humans have shown that the lymphatics are necessary for lung function from the neonatal period through adulthood. Furthermore, changes in the lymphatic vasculature are observed in nearly all respiratory diseases in which they have been analyzed. Recent work has pointed to a causative role for lymphatic dysfunction in the initiation and progression of lung disease, indicating that these vessels may be active players in pathologic processes in the lung. However, the mechanisms by which defects in lung lymphatic function are pathogenic are understudied, leaving many unanswered questions. A more comprehensive understanding of the mechanistic role of morphological, functional, and molecular changes in the lung lymphatic endothelium in respiratory diseases is a promising area of research that is likely to lead to novel therapeutic targets. In this review, we will discuss our current knowledge of the structure and function of the lung lymphatics and the role of these vessels in lung homeostasis and respiratory disease.

Role of chemokines in HPV-induced cancers

Human papillomaviruses (HPVs) cause cancers of the uterine cervix, oropharynx, anus, and vulvovaginal tract. Low-risk HPVs, such as HPV6 and 11, can also cause benign mucosal lesions including genital warts, and in patients with recurrent respiratory papillomatosis, lesions in the larynx, and on occasion, in the lungs. However, both high and less tumorigenic HPVs share a striking commonality in manipulating both innate and adaptive immune responses in HPV- infected keratinocytes, the natural host for HPV infection. In addition, immune/inflammatory cell infiltration into the tumor microenvironment influences cancer growth and prognosis, and this process is tightly regulated by different chemokines. Chemokines are small proteins and exert their biological effects by binding with G protein-coupled chemokine receptors (GPCRs) that are found on the surfaces of select target cells. Chemokines are not only involved in the establishment of a pro-tumorigenic microenvironment and organ-directed metastases but also involved in disease progression through enhancing tumor cell growth and proliferation. Therefore, having a solid grasp on chemokines and immune checkpoint modulators can help in the treatment of these cancers. In this review, we discuss the recent advances on the expression patterns and regulation of the main chemokines found in HPV-induced cancers, and their effects on both immune and non-immune cells in these lesions. Importantly, we also present the current knowledge of therapeutic interventions on the expression of specific chemokine and their receptors that have been shown to influence the development and progression of HPV-induced cancers.

Exacerbation of non-steroidal anti-inflammatory drug-induced enteropathy in C-C chemokine receptor type 7-deficient mice

BACKGROUND AND AIM

Non-steroidal anti-inflammatory drugs (NSAIDs) induce intestinal enteropathy and the pathophysiology is related to immune-mediated mechanisms. We aimed to investigate the role of C-C chemokine receptor type 7 (CCR7) which regulates immune cell migration in NSAID-induced enteropathy.

METHODS

Injury of the small intestine was evaluated 24 h after the subcutaneous injection of indomethacin in CCR7-deficient (Ccr7^-/- ) and wild-type (WT) mice. The cellular profile and cytokine production in intestinal cells were analyzed. Indomethacin-induced enteropathy was evaluated in mice adoptively transferred with CD103⁺ dendritic cells (DCs) from Ccr7^-/- or WT mice.

RESULTS

Indomethacin induced more severe intestinal injury in Ccr7^-/- mice than in WT mice. The major inflammatory cytokines were not increased and the proportion of regulatory T cells following indomethacin injection was not decreased in Ccr7^-/- mice compared with WT mice. The expression of interleukin (IL)-22 binding protein (IL-22BP), which inhibits IL-22 activity, was significantly higher in CD103⁺ DCs from Ccr7^-/- mice than those from WT mice. Mice adoptively transferred with CD103⁺ DCs isolated from Ccr7^-/- mice exhibited more severe intestinal injury following indomethacin injection compared with those adoptively transferred with CD103⁺ DCs of WT mice. Ccr7^-/- mice injected with indomethacin showed a significant reduction in regenerating islet-derived 1 (Reg1) mRNA expression, which is regulated by IL-22, in intestinal epithelial cells.

CONCLUSIONS

C-C chemokine receptor type 7 deficiency exacerbated NSAID-induced enteropathy in association with an altered phenotype of CD103⁺ DCs that produces IL-22BP. CCR7 contributes to protect the small intestine from NSAID-induced mucosal injury.

Role of Chemokines in the Pathogenesis of Visceral Leishmaniasis

Abstract:

Visceral leishmaniasis (VL; also known as kala-azar), caused by the protozoan parasite Leishmania donovani is characterized by the inability of the host to generate an effective immune response. The manifestations of the disease depends on involvement of various immune components such as activation of macrophages, cell mediated immunity, secretion of cytokines and chemokines, etc. Macrophages are the final host cells for Leishmania parasites to multiply, and they are the key to a controlled or aggravated response that leads to clinical symptoms. The two most common macrophage phenotypes are M1 and M2. The pro-inflammatory microenvironment (mainly by IL-1β, IL-6, IL-12, IL-23, and TNF-α cytokines) and tissue injury driven by classically activated macrophages (M1-like) and wound healing driven by alternatively activated macrophages (M2-like) in an anti-inflammatory environment (mainly by IL-10, TGF-β, chemokine ligand (CCL)1, CCL2, CCL17, CCL18, and CCL22). Moreover, on polarized Th cells, chemokine receptors are expressed differently. Typically, CXCR3 and CCR5 are preferentially expressed on polarized Th1 cells, whereas CCR3, CCR4 and CCR8 have been associated with the Th2 phenotype. Further, the ability of the host to produce a cell-mediated immune response capable of regulating and/or eliminating the parasite is critical in the fight against the disease. Here, we review the interactions between parasites and chemokines and chemokines receptors in the pathogenesis of VL.

Lymph node fibroblastic reticular cells regulate differentiation and function of CD4 T cells via CD25

Lymph node fibroblastic reticular cells (LN-FRCs) provide functional structure to LNs and play important roles in interactions between T cells and antigen-presenting cells. However, the direct impact of LN-FRCs on naive CD4+ T cell differentiation has not been explored. Here, we show that T cell zone FRCs of LNs (LN-TRCs) express CD25, the α chain of the IL-2 receptor heterotrimer. Moreover, LN-TRCs trans-present IL-2 to naive CD4+ T cells through CD25, thereby facilitating early IL-2-mediated signaling. CD25-deficient LN-TRCs exhibit attenuated STAT5 phosphorylation in naive CD4+ T cells during T cell differentiation, promoting T helper 17 (Th17) cell differentiation and Th17 response-related gene expression. In experimental autoimmune disease models, disease severity was elevated in mice lacking CD25 in LN-TRCs. Therefore, our results suggest that CD25 expression on LN-TRCs regulates CD4+ T cell differentiation by modulating early IL-2 signaling of neighboring, naive CD4+ T cells, influencing the overall properties of immune responses.

Molecular Signature of Tumor-Associated High Endothelial Venules That Can Predict Breast Cancer Survival

High endothelial venules (HEV) are specialized post-capillary venules that recruit naïve lymphocytes to lymph nodes. HEVs are essential for the development of adaptive immunity. HEVs can also develop in tumors where they are thought to be important for recruiting naïve T cells and B cells into the tumors and locally enhancing antitumor immunity by supporting the formation of tertiary lymphoid structures. Herein, we used comparative transcriptome analysis of human breast cancer to investigate genes differentially expressed between tumor-associated HEVs and the rest of the tumor vasculature. Tumor vessels highly expressing HEV-upregulated genes, such as the homeobox gene MEOX2 and the tetraspanin gene TSPAN7, were associated with extensive infiltration of T and B cells and the occurrence of tertiary lymphoid structures, which is known to predict therapeutic responses to immune-checkpoint inhibitors. Moreover, high transcript counts of these genes in clinical tumor specimens were associated with a significant survival benefit in advanced breast cancer. The molecular signature of HEVs identified herein may be useful for guiding immunotherapies and provides a new direction for investigating tumor-associated HEVs and their clinical significance. See related Spotlight by Gallimore, p. 371.

Analyzing Lymphatic Vessel Patterning in Adult Tissue

Whole-mount immunostaining allows intact tissue to be surveyed in three dimensions, avoiding the more restricted fields of view provided by visualizing thin sections. This technique is particularly useful for imaging lymphatic and blood networks by high-resolution confocal microscopy, revealing how such vessels are spatially positioned, the subcellular arrangements of individual antigens, and interactions with individual cells within the interstitium or vessel lumen. The purpose of this chapter is to provide a practical guide for obtaining images of lymphatic vessels following immunofluorescence staining, primarily in mouse skin.

Immune Responses to IAV Infection and the Roles of L-Selectin and ADAM17 in Lymphocyte Homing

Influenza A virus (IAV) infection is a global public health burden causing up to 650,000 deaths per year. Yearly vaccination programmes and anti-viral drugs currently have limited benefits; therefore, research into IAV is fundamental. Leukocyte trafficking is a crucial process which orchestrates the immune response to infection to protect the host. It involves several homing molecules and receptors on both blood vessels and leukocytes. A key mediator of this process is the transmembrane glycoprotein L-selectin, which binds to vascular addressins on blood vessel endothelial cells. L-selectin classically mediates homing of naïve and central memory lymphocytes to lymph nodes via high endothelial venules (HEVs). Recent studies have found that L-selectin is essential for homing of activated CD8⁺ T cells to influenza-infected lungs and reduction in virus load. A disintegrin and metalloproteinase 17 (ADAM17) is the primary regulator of cell surface levels of L-selectin. Understanding the mechanisms that regulate these two proteins are central to comprehending recruitment of T cells to sites of IAV infection. This review summarises the immune response to IAV infection in humans and mice and discusses the roles of L-selectin and ADAM17 in T lymphocyte homing during IAV infection.

OUP accepted manuscript

Organismal survival depends on a well-balanced immune system and maintenance of host–microbe mutualism. The fine-tuned relationship between the gut microbiota and host immunity is constantly challenged by opportunistic bacteria testing the integrity of gastrointestinal (GI) barrier defenses. Barrier dysfunction reduces immunological tolerance towards otherwise innocuous microbes; it is a process that may instigate chronic inflammation. Paradoxically, sustained inflammation further diminishes barrier function, enabling bacterial translocation to extra-intestinal tissues. Once translocated, these bacteria stimulate systemic inflammation, thereby compromising organ function. While genetic risk alleles associate with barrier dysfunction, environmental stressors are key triggers of GI inflammation and associated breakdown in immune tolerance towards resident gut microbes. As dietary components dictate substrate availability, they also orchestrate microbiota composition and function, including migratory and pro-inflammatory potential, thus holding the capacity to fuel both GI and extra-intestinal inflammation. Additionally, Western diet consumption may weaken barrier defenses via curbed Paneth cell function and diminished host-defense peptide secretion. This review focuses on intervenable niches of host–microbe interactions and mucosal immunity with the ambition to provide a framework of plausible strategies to improve barrier function and regain tolerance in the inflamed mucosa via nutritional intervention.

Fucoxanthin Prevents Pancreatic Tumorigenesis in C57BL/6J Mice That Received Allogenic and Orthotopic Transplants of Cancer Cells

Fucoxanthin (Fx) is a marine carotenoid with anti-inflammatory and anti-cancer properties in various animal models of carcinogenesis. However, there is currently no information on the effects of Fx in animal models of pancreatic cancer. We investigated the chemopreventive effects of Fx in C57BL/6J mice that received allogenic and orthotopic transplantations of cancer cells (KMPC44) derived from a pancreatic cancer murine model (Ptf1aCre/+; LSL-krasG12D/+). Using microarray, immunofluorescence, western blot, and siRNA analyses, alterations in cancer-related genes and protein expression were evaluated in pancreatic tumors of Fx-administered mice. Fx administration prevented the adenocarcinoma (ADC) development of pancreatic and parietal peritoneum tissues in a pancreatic cancer murine model, but not the incidence of ADC. Gene and protein expressions showed that the suppression of chemokine (C-C motif) ligand 21 (CCL21)/chemokine receptor 7 (CCR7) axis, its downstream of Rho A, B- and T-lymphocyte attenuator (BTLA), N-cadherin, αSMA, pFAK(Tyr397), and pPaxillin(Tyr31) were significantly suppressed in the pancreatic tumors of mice treated with Fx. In addition, Ccr7 knockdown significantly attenuated the growth of KMPC44 cells. These results suggest that Fx is a promising candidate for pancreatic cancer chemoprevention that mediates the suppression of the CCL21/CCR7 axis, BTLA, tumor microenvironment, epithelial mesenchymal transition, and adhesion.

Solid stress impairs lymphocyte infiltration into lymph-node metastases

Strong and durable anticancer immune responses are associated with the generation of activated cancer-specific T cells in the draining lymph nodes. However, cancer cells can colonize lymph nodes and drive tumour progression. Here, we show that lymphocytes fail to penetrate metastatic lesions in lymph nodes. In tissue from patients with breast, colon, and head and neck cancers, as well as in mice with spontaneously developing breast-cancer lymph-node metastases, we found that lymphocyte exclusion from nodal lesions is associated with the presence of solid stress caused by lesion growth, that solid stress induces reductions in the number of functional high endothelial venules in the nodes, and that relieving solid stress in the mice increased the presence of lymphocytes in lymph-node lesions by about 15-fold. Solid-stress-mediated impairment of lymphocyte infiltration into lymph-node metastases suggests a therapeutic route for overcoming T-cell exclusion during immunotherapy.

Immunotherapy in Recurrent/Metastatic Squamous Cell Carcinoma of the Head and Neck

Head and neck cancer is the 6^th most common cancer worldwide with the most common histology being squamous cell carcinoma (HNSCC). While the majority of patients present at a stage where curative intent therapy is possible, when patients recur and/or develop metastatic disease, outcomes are generally poor, especially with systemic therapy alone, and they lag behind other solid tumors. Over the last decade immunotherapy has revolutionized the field of oncology, and anti-PD-1-based therapy has changed the standard of care in recurrent/metastatic (R/M) HNSCC as well. With these gains have come new questions to continue to move the field forward. In this review, we discuss the tumor immune microenvironment and predictive biomarkers and current status and future directions for immunotherapy in recurrent/metastatic head and neck cancer.

Development of an Individualized Immune Prognostic Signature for Clear Cell Renal Cell Carcinoma through the Identification of Differential Immune Genes

Increasing evidence has shown that tumor microenvironments are an important feature in clear cell renal cell carcinoma (ccRCC) carcinogenesis and therapeutic efficacy. In this study, two subtypes of ccRCC, high- and low-immune groups, were identified based on the immune gene datasets, of which the differential immune genes were identified accordingly. Furthermore, we constructed a risk prognosis model using five immune genes, specifically, AQP9, KIAA1429, HAMP, CCL13, and CCL21. This model was highly predictive of ccRCC clinical characteristics and showed potential for use in immunotherapy. Furthermore, the five identified genes were highly correlated with the abundance of B cells, CD4 T cells, CD8 T cells, macrophages, neutrophils, and dendritic cells in the tumor microenvironments. Among them, AQP9, KIAA1429, and HAMP exhibited significant prognostic potential. These findings indicate that monitoring and operating tumor microenvironments are of great significance for ccRCC prognosis and precise immunotherapy.

Chemokine C-C motif ligand 21 synergized with programmed death-ligand 1 blockade restrains tumor growth

Programmed death‐ligand 1 (PD‐L1) blockade has revolutionized the prognosis of several cancers, but shows a weak effect on pancreatic cancer (PC) due to poor effective immune infiltration. Chemokine C‐C motif ligand 21 (CCL21), a chemokine promoting T cell immunity by recruiting and colocalizing dendritic cells (DCs) and T cells, serves as a potential antitumor agent in many cancers. However, its antitumor response and mechanism combined with PD‐L1 blockade in PC remain unclear. In our study, we found CCL21 played an important role in leukocyte chemotaxis, inflammatory response, and positive regulation of PI3K‐AKT signaling in PC using Metascape and gene set enrichment analysis. The CCL21 level was verified to be positively correlated with infiltration of CD8⁺ T cells by the CIBERSORT algorithm, but no significant difference in survival was observed in either The Cancer Genome Atlas or the International Cancer Genome Consortium cohort when stratified by CCL21 expression. Additionally, we found the growth rate of allograft tumors was reduced and T cell infiltration was increased, but tumor PD‐L1 abundance elevated simultaneously in the CCL21‐overexpressed tumors. Then, CCL21 was further verified to increase tumor PD‐L1 level through the AKT‐glycogen synthase kinase‐3β axis in human PC cells, which partly impaired the antitumor T cell immunity. Finally, the combination of CCL21 and PD‐L1 blockade showed superior synergistic tumor suppression in vitro and in vivo. Together, our findings suggested that CCL21 in combination with PD‐L1 blockade might be an efficient and promising option for the treatment of PC.

Leukaemia: a model metastatic disease

In contrast to solid cancers, which often require genetic modifications and complex cellular reprogramming for effective metastatic dissemination, leukaemic cells uniquely possess the innate ability for migration and invasion. Dedifferentiated, malignant leukocytes retain the benign leukocytes' capacity for cell motility and survival in the circulation, while acquiring the potential for rapid and uncontrolled cell division. For these reasons, leukaemias, although not traditionally considered as metastatic diseases, are in fact models of highly efficient metastatic spread. Accordingly, they are often aggressive and challenging diseases to treat. In this Perspective, we discuss the key molecular processes that facilitate metastasis in a variety of leukaemic subtypes, the clinical significance of leukaemic invasion into specific tissues and the current pipeline of treatments targeting leukaemia metastasis.

A humanized monoclonal antibody against the endothelial chemokine CCL21 for the diagnosis and treatment of inflammatory bowel disease

Chemokines are small proteins that promote leukocyte migration during development, infection, and inflammation. We and others isolated the unique chemokine CCL21, a potent chemo-attractant for naïve T-cells, naïve B-cells, and immature dendritic cells. CCL21 has a 37 amino acid carboxy terminal extension that is distinct from the rest of the chemokine family, which is thought to anchor it to venule endothelium where the amino terminus can interact with its cognate receptor, CCR7. We and others have reported that venule endothelium expressing CCL21 plays a crucial role in attracting naïve immune cells to sites of antigen presentation. In this study we generated a series of monoclonal antibodies to the amino terminus of CCL21 in an attempt to generate an antibody that blocked the interaction of CCL21 with its receptor CCR7. We found one humanized clone that blocked naïve T-cell migration towards CCL21, while memory effector T-cells were less affected. Using this monoclonal antibody, we also demonstrated that CCL21 is expressed in the mucosal venule endothelium of the large majority of inflammatory bowel diseases (IBD), including Crohn's disease, ulcerative colitis, and also in celiac disease. This expression correlated with active IBD in 5 of 6 cases, whereas none of 6 normal bowel biopsies had CCL21 expression. This study raises the possibility that this monoclonal antibody could be used to diagnose initial or recurrent of IBD. Significantly, this antibody could also be used for therapeutic intervention in IBD by selectively interfering with recruitment of naïve immune effector cells to sites of antigen presentation, without harming overall memory immunity.

STING Gain-of-Function Disrupts Lymph Node Organogenesis and Innate Lymphoid Cell Development in Mice

STING gain-of-function causes autoimmunity and immunodeficiency in mice and STING-associated vasculopathy with onset in infancy (SAVI) in humans. Here, we report that STING gain-of-function in mice prevents development of lymph nodes and Peyer's patches. We show that the absence of secondary lymphoid organs is associated with diminished numbers of innate lymphoid cells (ILCs), including lymphoid tissue inducer (LTi) cells. Although wild-type (WT) α4β7⁺ progenitors differentiate efficiently into LTi cells, STING gain-of-function progenitors do not. Furthermore, STING gain-of-function impairs development of all types of ILCs. Patients with STING gain-of-function mutations have fewer ILCs, although they still have lymph nodes. In mice, expression of the STING mutant in RORγT-positive lineages prevents development of lymph nodes and reduces numbers of LTi cells. RORγT lineage-specific expression of STING gain-of-function also causes lung disease. Since RORγT is expressed exclusively in LTi cells during fetal development, our findings suggest that STING gain-of-function prevents lymph node organogenesis by reducing LTi cell numbers in mice.

Landscape of Exhausted Virus-Specific CD8 T Cells in Chronic LCMV Infection

A hallmark of chronic infections is the presence of exhausted CD8 T cells, characterized by a distinct transcriptional program compared with functional effector or memory cells, co-expression of multiple inhibitory receptors, and impaired effector function, mainly driven by recurrent T cell receptor engagement. In the context of chronic lymphocytic choriomeningitis virus (LCMV) infection in mice, most studies focused on studying splenic virus-specific CD8 T cells. Here, we provide a detailed characterization of exhausted CD8 T cells isolated from six different tissues during established LCMV infection, using single-cell RNA sequencing. Our data reveal that exhausted cells are heterogeneous, adopt organ-specific transcriptomic profiles, and can be divided into five main functional subpopulations: advanced exhaustion, effector-like, intermediate, proliferating, or memory-like. Adoptive transfer experiments showed that these phenotypes are plastic, suggesting that the tissue microenvironment has a major impact in shaping the phenotype and function of virus-specific CD8 T cells during chronic infection.

High endothelial venules (HEVs) in immunity, inflammation and cancer

High endothelial venules (HEVs) are specialized blood vessels mediating lymphocyte trafficking to lymph nodes (LNs) and other secondary lymphoid organs. By supporting high levels of lymphocyte extravasation from the blood, HEVs play an essential role in lymphocyte recirculation and immune surveillance for foreign invaders (bacterial and viral infections) and alterations in the body’s own cells (neoantigens in cancer). The HEV network expands during inflammation in immune-stimulated LNs and is profoundly remodeled in metastatic and tumor-draining LNs. HEV-like blood vessels expressing high levels of the HEV-specific sulfated MECA-79 antigens are induced in non-lymphoid tissues at sites of chronic inflammation in many human inflammatory and allergic diseases, including rheumatoid arthritis, Crohn’s disease, allergic rhinitis and asthma. Such vessels are believed to contribute to the amplification and maintenance of chronic inflammation. MECA-79⁺ tumor-associated HEVs (TA-HEVs) are frequently found in human tumors in CD3⁺ T cell-rich areas or CD20⁺ B-cell rich tertiary lymphoid structures (TLSs). TA-HEVs have been proposed to play important roles in lymphocyte entry into tumors, a process essential for successful antitumor immunity and lymphocyte-mediated cancer immunotherapy with immune checkpoint inhibitors, vaccines or adoptive T cell therapy. In this review, we highlight the phenotype and function of HEVs in homeostatic, inflamed and tumor-draining lymph nodes, and those of HEV-like blood vessels in chronic inflammatory diseases. Furthermore, we discuss the role and regulation of TA-HEVs in human cancer and mouse tumor models.

CNS-Draining Meningeal Lymphatic Vasculature: Roles, Conundrums and Future Challenges

A genuine and functional lymphatic vascular system is found in the meninges that sheath the central nervous system (CNS). This unexpected (re)discovery led to a reevaluation of CNS fluid and solute drainage mechanisms, neuroimmune interactions and the involvement of meningeal lymphatics in the initiation and progression of neurological disorders. In this manuscript, we provide an overview of the development, morphology and unique functional features of meningeal lymphatics. An outline of the different factors that affect meningeal lymphatic function, such as growth factor signaling and aging, and their impact on the continuous drainage of brain-derived molecules and meningeal immune cells into the cervical lymph nodes is also provided. We also highlight the most recent discoveries about the roles of the CNS-draining lymphatic vasculature in different pathologies that have a strong neuroinflammatory component, including brain trauma, tumors, and aging-associated neurodegenerative diseases like Alzheimer’s and Parkinson’s. Lastly, we provide a critical appraisal of the conundrums, challenges and exciting questions involving the meningeal lymphatic system that ought to be investigated in years to come.

Scavenging of soluble and immobilized CCL21 by ACKR4 regulates peripheral dendritic cell emigration

Leukocyte homing driven by the chemokine CCL21 is pivotal for adaptive immunity because it controls dendritic cell (DC) and T cell migration through CCR7. ACKR4 scavenges CCL21 and has been shown to play an essential role in DC trafficking at the steady state and during immune responses to tumors and cutaneous inflammation. However, the mechanism by which ACKR4 regulates peripheral DC migration is unknown, and the extent to which it regulates CCL21 in steady-state skin and lymph nodes (LNs) is contested. Specifically, our previous findings that CCL21 levels are increased in LNs of ACKR4-deficient mice [I. Comerford et al., Blood 116, 4130-4140 (2010)] were refuted [M. H. Ulvmar et al., Nat. Immunol. 15, 623-630 (2014)], and no differences in CCL21 levels in steady-state skin of ACKR4-deficient mice were reported despite compromised CCR7-dependent DC egress in these animals [S. A. Bryce et al., J. Immunol. 196, 3341-3353 (2016)]. Here, we resolve these issues and reveal that two forms of CCL21, full-length immobilized and cleaved soluble CCL21, exist in steady-state barrier tissues, and both are regulated by ACKR4. Without ACKR4, extracellular CCL21 gradients in barrier sites are saturated and nonfunctional, DCs cannot home directly to lymphatic vessels, and excess soluble CCL21 from peripheral tissues pollutes downstream LNs. The results identify the mechanism by which ACKR4 controls DC migration in barrier tissues and reveal a complex mode of CCL21 regulation in vivo, which enhances understanding of functional chemokine gradient formation.

In Sickness and in Health: The Immunological Roles of the Lymphatic System

The lymphatic system plays crucial roles in immunity far beyond those of simply providing conduits for leukocytes and antigens in lymph fluid. Endothelial cells within this vasculature are distinct and highly specialized to perform roles based upon their location. Afferent lymphatic capillaries have unique intercellular junctions for efficient uptake of fluid and macromolecules, while expressing chemotactic and adhesion molecules that permit selective trafficking of specific immune cell subsets. Moreover, in response to events within peripheral tissue such as inflammation or infection, soluble factors from lymphatic endothelial cells exert “remote control” to modulate leukocyte migration across high endothelial venules from the blood to lymph nodes draining the tissue. These immune hubs are highly organized and perfectly arrayed to survey antigens from peripheral tissue while optimizing encounters between antigen-presenting cells and cognate lymphocytes. Furthermore, subsets of lymphatic endothelial cells exhibit differences in gene expression relating to specific functions and locality within the lymph node, facilitating both innate and acquired immune responses through antigen presentation, lymph node remodeling and regulation of leukocyte entry and exit. This review details the immune cell subsets in afferent and efferent lymph, and explores the mechanisms by which endothelial cells of the lymphatic system regulate such trafficking, for immune surveillance and tolerance during steady-state conditions, and in response to infection, acute and chronic inflammation, and subsequent resolution.

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.

The BCMA-Targeted Fourth-Generation CAR-T Cells Secreting IL-7 and CCL19 for Therapy of Refractory/Recurrent Multiple Myeloma

Chimeric antigen receptor (CAR) technology has revolutionized cancer treatment, particularly in malignant hematological tumors. Currently, the BCMA-targeted second-generation CAR-T cells have showed impressive efficacy in the treatment of refractory/relapsed multiple myeloma (R/R MM), but up to 50% relapse remains to be addressed urgently. Here we constructed the BCMA-targeted fourth-generation CAR-T cells expressing IL-7 and CCL19 (i.e., BCMA-7 × 19 CAR-T cells), and demonstrated that BCMA-7 × 19 CAR-T cells exhibited superior expansion, differentiation, migration and cytotoxicity. Furthermore, we have been carrying out the first-in-human clinical trial for therapy of R/R MM by use of BCMA-7 × 19 CAR-T cells (ClinicalTrials.gov Identifier: NCT03778346), which preliminarily showed promising safety and efficacy in first two enrolled patients. The two patients achieved a CR and VGPR with Grade 1 cytokine release syndrome only 1 month after one dose of CAR-T cell infusion, and the responses lasted more than 12-month. Taken together, BCMA-7 × 19 CAR-T cells were safe and effective against refractory/relapsed multiple myeloma and thus warranted further clinical study.

Inflammatory Chemokines in Atherosclerosis

Atherosclerosis is a long-term, chronic inflammatory disease of the vessel wall leading to the formation of occlusive or rupture-prone lesions in large arteries. Complications of atherosclerosis can become severe and lead to cardiovascular diseases (CVD) with lethal consequences. During the last three decades, chemokines and their receptors earned great attention in the research of atherosclerosis as they play a key role in development and progression of atherosclerotic lesions. They orchestrate activation, recruitment, and infiltration of immune cells and subsequent phenotypic changes, e.g., increased uptake of oxidized low-density lipoprotein (oxLDL) by macrophages, promoting the development of foam cells, a key feature developing plaques. In addition, chemokines and their receptors maintain homing of adaptive immune cells but also drive pro-atherosclerotic leukocyte responses. Recently, specific targeting, e.g., by applying cell specific knock out models have shed new light on their functions in chronic vascular inflammation. This article reviews recent findings on the role of immunomodulatory chemokines in the development of atherosclerosis and their potential for targeting.

The Involvement of Innate and Adaptive Immunity in the Initiation and Perpetuation of Sjögren's Syndrome

Sjogren’s syndrome (SS) is a chronic autoimmune disease characterized by the infiltration of exocrine glands including salivary and lachrymal glands responsible for the classical dry eyes and mouth symptoms (sicca syndrome). The spectrum of disease manifestations stretches beyond the classical sicca syndrome with systemic manifestations including arthritis, interstitial lung involvement, and neurological involvement. The pathophysiology underlying SS is not well deciphered, but several converging lines of evidence have supported the conjuncture of different factors interplaying together to foster the initiation and perpetuation of the disease. The innate and adaptive immune system play a cardinal role in this process. In this review, we discuss the inherent parts played by both the innate and adaptive immune system in the pathogenesis of SS.

What Is on the Horizon for Novel Immunotherapies in Lung Cancer?

Programmed death (ligand) 1 checkpoint inhibitors have become standard treatment in patients with non-small cell lung cancer. Recently, combinations of nivolumab and ipilimumab have entered the clinic based on regulatory approval. Oftentimes, these checkpoint inhibitors are given in conjunction with chemotherapy. Through increased understanding of checkpoint evasion by cancer cells, many promising studies using combination therapies have continued to develop that aim to attack cancer cells by eliciting immunogenic responses through different modalities. Novel approaches include (1) using vaccines to trigger immune response, (2) combining multiple checkpoint inhibitors, (3) targeting inflammatory responses, (4) utilizing multitargeted tyrosine kinase inhibitors, (5) employing agonists of T-cell stimulators, and (6) applying specific biomarker antagonists to treat lung cancer patients. Herein, we discuss several studies that aim to answer what lies ahead in lung cancer treatment.

Induction of High Endothelial Venule-like Vessels in Oral and Cutaneous Lichen Planus: A Comparative Study

Lichen planus (LP) is a chronic inflammatory mucocutaneous disease involving the oral mucosa and skin. Both oral LP (OLP) and cutaneous LP (CLP) are histopathologically characterized by dense subepithelial lymphocyte infiltrates; however, the mechanisms underlying lymphocyte recruitment to sites of LP lesions are not fully understood. Here, we assessed the induction of peripheral lymph node addressin (PNAd)-expressing high endothelial venule (HEV)-like vessels in 19 OLP and 17 CLP cases. To do so, we performed immunohistochemical staining for PNAd and CD34, followed by quantitative analysis. We also conducted triple immunohistochemistry for PNAd and either CD3 and CD20 or CD4 and CD8 to identify the lymphocyte subset preferentially recruited via HEV-like vessels. PNAd-expressing HEV-like vessels were induced in and around lymphocyte aggregates in all cases of OLP and in 10 of 17 CLP cases, and these vessels were more frequently observed in OLP relative to CLP. Although the number of T-cells attached per HEV-like vessel exceeded the number of B-cells in both OLP and CLP, the number of CD4⁺ T-cells attached was greater than the number of CD8⁺ T-cells only in OLP. These findings combined suggest that PNAd-expressing HEV-like vessels play a more important role in the pathogenesis of OLP compared with CLP.

Area under Immunosurveillance: Dedicated Roles of Memory CD8 T-Cell Subsets

Immunological memory, defined as the ability to respond in an enhanced manner upon secondary encounter with the same pathogen, can provide substantial protection against infectious disease. The improved protection is mediated in part by different populations of memory CD8 T cells that are retained after primary infection. Memory cells persist in the absence of pathogen-derived antigens and enable secondary CD8 T-cell responses with accelerated kinetics and of larger magnitude after reencounter with the same pathogen. At least three subsets of memory T cells have been defined that are referred to as central memory CD8 T cells (Tcm), effector memory CD8 T cells (Tem), and tissue-resident memory CD8 T cells (Trm). Tcm and Tem are circulating memory T cells that mediate bodywide immune surveillance in search of invading pathogens. In contrast, Trm permanently reside in peripheral barrier tissues, where they form a stationary defensive line of sentinels that alert the immune system upon pathogen reencounter. The characterization of these different subsets has been instrumental in our understanding of the strategies that memory T cells employ to counter invading pathogens. It is clear that memory T cells not only have a numerical advantage over naive T cells resulting in improved protection in secondary responses, but also acquire distinct sets of competencies that assist in pathogen clearance. Nevertheless, inherent challenges are associated with the allocation of memory T cells to a limited number of subsets. The classification of memory T cells into Tcm, Tem, and Trm may not take into account the full extent of the heterogeneity that is observed in the memory population. Therefore, in this review, we will revisit the current classification of memory subsets, elaborate on functional and migratory properties attributed to Tcm, Tem, and Trm, and discuss how potential heterogeneity within these populations arises and persists.

Densities of decidual high endothelial venules correlate with T-cell influx in healthy pregnancies and idiopathic recurrent pregnancy losses

STUDY QUESTION

Do high endothelial venules (HEVs) appear in the uterus of healthy and pathological pregnancies?

SUMMARY ANSWER

Our study reveals that HEVs are present in the non-pregnant endometrium and decidua parietalis (decP) but decline upon placentation in decidua basalis (decB) and are less abundant in decidual tissues from idiopathic, recurrent pregnancy losses (RPLs).

WHAT IS KNOWN ALREADY

RPL is associated with a compromised decidual vascular phenotype.

STUDY DESIGN, SIZE, DURATION

Endometrial (n = 29) and first trimester decidual (n = 86, 6-12th week of gestation) tissue samples obtained from endometrial biopsies or elective pregnancy terminations were used to determine the number of HEVs and T cells. In addition, quantification of HEVs and immune cells was performed in a cohort of decidual tissues from RPL (n = 25).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Position and frequency of HEVs were determined in non-pregnant endometrial as well as decidual tissue sections using immunofluorescence (IF) staining with antibodies against E-selectin, intercellular adhesion molecule, von Willebrand factor, ephrin receptor B4, CD34 and a carbohydrate epitope specific to HEVs (MECA-79). Immune cell distribution and characterization was determined by antibodies recognizing CD45 and CD3 by IF staining- and flow cytometry-based analyses. Antibodies against c-c motif chemokine ligand 21 (CCL21) and lymphotoxin-beta were used in IF staining and Western blot analyses of decidual tissues.

MAIN RESULTS AND THE ROLE OF CHANCE

Functional HEVs are found in high numbers in the secretory endometrium and decP but decline in numbers upon placentation in decB (P ≤ 0.001). Decidua parietalis tissues contain higher levels of the HEV-maintaining factor lymphotoxin beta and decP-associated HEVs also express CCL21 (P ≤ 0.05), a potent T-cell chemoattractant. Moreover, there is a positive correlation between the numbers of decidual HEVs and the abundance of CD3+ cells in decidual tissue sections (P ≤ 0.001). In-depth analysis of a RPL tissue collection revealed a decreased decB (P ≤ 0.01) and decP (P ≤ 0.01) HEV density as well as reduced numbers of T cells in decB (P ≤ 0.05) and decP (P ≤ .001) sections when compared with age-matched healthy control samples. Using receiver-operating characteristics analyses, we found significant predictive values for the ratios of CD3/CD45 (P < 0.001) and HEVs/total vessels (P < 0.001) for the occurrence of RPL.

LIMITATIONS, REASONS FOR CAUTION

Analyses were performed in first trimester decidual tissues from elective terminations of pregnancy or non-pregnant endometrium samples from patients diagnosed with non-endometrial pathologies including cervical polyps, ovarian cysts and myomas. First trimester decidual tissues may include pregnancies which potentially would have developed placental disorders later in gestation. In addition, our cohort of non-pregnant endometrium may not reflect the endometrial vascular phenotype of healthy women. Finally, determination of immune cell distributions in the patient cohorts studied may be influenced by the different modes of tissue derivation. Pregnancy terminations were performed by surgical aspiration, endometrial tissues were obtained by biopsies and RPL tissues were collected after spontaneous loss of pregnancy.

WIDER IMPLICATIONS OF THE FINDINGS

In this study, we propose an inherent mechanism by which the endometrium and in particular the decidua control T-cell recruitment. By demonstrating reduced HEV densities and numbers of T cells in decB and decP tissues of RPL samples we further support previous findings reporting an altered vascular phenotype in early pregnancy loss. Altogether, the findings provide important information to further decipher the etiologies of unexplained RPL.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Austrian Science Fund (P31470 B30 to M.K.) and by the Austrian National Bank (17613ONB to J.P.). There are no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

CC Chemokines in a Tumor: A Review of Pro-Cancer and Anti-Cancer Properties of Receptors CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 Ligands

CC chemokines (or β-chemokines) are 28 chemotactic cytokines with an N-terminal CC domain that play an important role in immune system cells, such as CD4⁺ and CD8⁺ lymphocytes, dendritic cells, eosinophils, macrophages, monocytes, and NK cells, as well in neoplasia. In this review, we discuss human CC motif chemokine ligands: CCL1, CCL3, CCL4, CCL5, CCL18, CCL19, CCL20, CCL21, CCL25, CCL27, and CCL28 (CC motif chemokine receptor CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 ligands). We present their functioning in human physiology and in neoplasia, including their role in the proliferation, apoptosis resistance, drug resistance, migration, and invasion of cancer cells. We discuss the significance of chemokine receptors in organ-specific metastasis, as well as the influence of each chemokine on the recruitment of various cells to the tumor niche, such as cancer-associated fibroblasts (CAF), Kupffer cells, myeloid-derived suppressor cells (MDSC), osteoclasts, tumor-associated macrophages (TAM), tumor-infiltrating lymphocytes (TIL), and regulatory T cells (T_reg). Finally, we show how the effect of the chemokines on vascular endothelial cells and lymphatic endothelial cells leads to angiogenesis and lymphangiogenesis.

Why do intestinal epithelial cells express MHC class II?

Intestinal epithelial cells (IECs) constitute the border between the vast antigen load present in the intestinal lumen and the mucosal immune compartment. Their ability to express antigen processing and presentation machinery evokes the question whether IECs function as non-conventional antigen-presenting cells. Major histocompatibility complex (MHC) class II expression by non-haematopoietic cells, such as IECs, is tightly regulated by the class II transactivator (CIITA) and is classically induced by IFN-γ. As MHC class II expression by IECs is upregulated under inflammatory conditions, it has been proposed to activate effector CD4+ T (Teff) cells. However, other studies have reported contradictory results and instead suggested a suppressive role of antigen presentation by IECs, through regulatory T (Treg)-cell activation. Recent studies investigating the role of MHC class II + exosomes released by IECs also reported conflicting findings of either immune enhancing or immunosuppressive activities. Moreover, in addition to modulating inflammatory responses, recent findings suggest that MHC class II expression by intestinal stem cells may elicit crosstalk that promotes epithelial renewal. A more complete understanding of the different consequences of IEC MHC class II antigen presentation will guide future efforts to modulate this pathway to selectively invoke protective immunity while maintaining tolerance to beneficial antigens.

Coexpression of IL7 and CCL21 Increases Efficacy of CAR-T Cells in Solid Tumors without Requiring Preconditioned Lymphodepletion

PURPOSE

T-cell recruitment, survival, and proliferation are the important limitations to chimeric antigen receptor (CAR) T cells therapy in the treatment of solid tumors. In this study, we engineered CAR-T cells to coexpress cytokines IL7 and CCL21 (7 × 21 CAR-T), a cytokine combination in order to improve proliferation and chemotaxis of CAR-T cells.

EXPERIMENTAL DESIGN

CLDN18.2-specific second-generation CAR-T cells coexpressing cytokines were prepared using retroviral vector transduction. The proliferation and migration of genetically engineered CAR-T cells were evaluated in vitro. The antitumor activities of genetically engineered CAR-T cells were evaluated against multiple solid tumors in C57BL/6 mice in vivo.

RESULTS

In vitro, the proliferation and chemotaxis of 7 × 21 CAR-T cells are significantly improved when compared with those of the conventional CAR-T cells. In vivo, 7 × 21 CAR-T cells revealed superior therapeutic effects to either conventional CAR-T cells or 7 × 19 CAR-T cells which coexpress IL7 and CCL19 as previously reported in three different solid tumors without cyclophosphamide precondition. Interestingly, 7 × 21 CAR-T cells could also suppress the tumor growth with heterogeneous antigen expression and even induce tumor complete remission. Mechanistically, IL7 and CCL21 significantly improved survival and infiltration of CAR-T cells and dendritic cells in tumor. In addition, CCL21 also inhibited the tumor angiogenesis as proved by IHC.

CONCLUSIONS

Coexpression of IL7 and CCL21 could boost CAR-T cells' antitumor activity, and 7 × 21 CAR-T cells may be served as a promising therapy strategy for solid tumors.

Hypoxia Alters the Expression of CC Chemokines and CC Chemokine Receptors in a Tumor-A Literature Review

Hypoxia, i.e., oxygen deficiency condition, is one of the most important factors promoting the growth of tumors. Since its effect on the chemokine system is crucial in understanding the changes in the recruitment of cells to a tumor niche, in this review we have gathered all the available data about the impact of hypoxia on β chemokines. In the introduction, we present the chronic (continuous, non-interrupted) and cycling (intermittent, transient) hypoxia together with the mechanisms of activation of hypoxia inducible factors (HIF-1 and HIF-2) and NF-κB. Then we describe the effect of hypoxia on the expression of chemokines with the CC motif: CCL1, CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL13, CCL15, CCL16, CCL17, CCL18, CCL19, CCL20, CCL21, CCL22, CCL24, CCL25, CCL26, CCL27, CCL28 together with CC chemokine receptors: CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10. To better understand the effect of hypoxia on neoplastic processes and changes in the expression of the described proteins, we summarize the available data in a table which shows the effect of individual chemokines on angiogenesis, lymphangiogenesis, and recruitment of eosinophils, myeloid-derived suppressor cells (MDSC), regulatory T cells (T_reg), and tumor-associated macrophages (TAM) to a tumor niche.

Nanoformulation of CCL21 greatly increases its effectiveness as an immunotherapy for neuroblastoma

Neuroblastoma is the most commonly diagnosed extracranial solid tumor in children. The patients with aggressive metastatic disease or refractory/relapsed neuroblastoma currently face a dismally low chance of survival. Thus, there is a great need for more effective therapies for this illness. In previous studies, we, as well as others, showed that the immune cell chemoattractant C-C motif chemokine ligand 21 (CCL21) is effective as an intratumoral therapy able to slow the growth of cancers. In this current study, we developed and tested an injectable, slow-release, uniform, and optimally loaded alginate nanoformulation of CCL21 as a means to provide prolonged intratumoral treatment. The alginate-nanoformulated CCL21, when injected intratumorally into mice bearing neuroblastoma lesions, significantly prolonged survival and decreased the tumor growth rate compared to CCL21 alone, empty nanoparticles, or buffer. Notably, we also observed complete tumor clearance and subsequent full protection against tumor rechallenge in 33% of nanoformulated CCL21-treated mice. Greater intratumoral presence of nanoformulated CCL21, compared to free CCL21, at days 1 and 2 after treatment ended was confirmed through fluorescent labeling and tracking. Nanoformulated CCL21-treated tumors exhibited a general pattern of prolonged increases in anti-tumor cytokines and relatively lower levels of pro-tumor cytokines in comparison to tumors treated with CCL21 alone or buffer only. Thus, this novel nanoformulation of CCL21 is an effective treatment for neuroblastoma, and may have potential for the delivery of CCL21 to other types of solid tumors in the future and as a slow-release delivery modality for other immunotherapies.

Periarteriolar stroma cells guide T cells from the red to the white pulp in the spleen

While both the spleen and lymph nodes are called secondary lymphoid tissues, how lymphocytes enter these tissues are quite different from each other. This is because the architecture of the two types of organs and the mode of lymphocyte migration into these organs are quite distinct. In the spleen, T cells are passively released in the blood flow from the arterioles in the red pulp and marginal zone area. In contrast, T cells in the blood are actively captured on high endothelial venules in lymph nodes by the coordinated actions of CCR7 and several adhesion molecules. A recent finding indicates that T cells, released in the red pulp and marginal zone areas, actively find their way to the white zone by utilizing the migration track created by periarteriolar stromal cells. This finding adds one more piece to our understanding of lymphocyte migration for effective adaptive immune responses in the spleen.

Myeloid Cell-Intrinsic IRF5 Promotes T Cell Responses through Multiple Distinct Checkpoints In Vivo, and IRF5 Immune-Mediated Disease Risk Variants Modulate These Myeloid Cell Functions

Common IRF5 genetic risk variants associated with multiple immune-mediated diseases are a major determinant of interindividual variability in pattern-recognition receptor (PRR)-induced cytokines in myeloid cells. However, how myeloid cell-intrinsic IRF5 regulates the multiple distinct checkpoints mediating T cell outcomes in vivo and IRF5-dependent mechanisms contributing to these distinct checkpoints are not well defined. Using an in vivo Ag-specific adoptive T cell transfer approach into Irf5^-/- mice, we found that T cell-extrinsic IRF5 regulated T cell outcomes at multiple critical checkpoints, including chemokine-mediated T cell trafficking into lymph nodes and PDK1-dependent soluble Ag uptake, costimulatory molecule upregulation, and secretion of Th1 (IL-12)- and Th17 (IL-23, IL-1β, and IL-6)-conditioning cytokines by myeloid cells, which then cross-regulated Th2 and regulatory T cells. IRF5 was required for PRR-induced MAPK and NF-κB activation, which, in turn, regulated these key outcomes in myeloid cells. Importantly, mice with IRF5 deleted from myeloid cells demonstrated T cell outcomes similar to those observed in Irf5^-/- mice. Complementation of IL-12 and IL-23 was able to restore T cell differentiation both in vitro and in vivo in the context of myeloid cell-deficient IRF5. Finally, human monocyte-derived dendritic cells from IRF5 disease-associated genetic risk carriers leading to increased IRF5 expression demonstrated increased Ag uptake and increased PRR-induced costimulatory molecule expression and chemokine and cytokine secretion compared with monocyte-derived dendritic cells from low-expressing IRF5 genetic variant carriers. These data establish that myeloid cell-intrinsic IRF5 regulates multiple distinct checkpoints in T cell activation and differentiation and that these are modulated by IRF5 disease risk variants.

The Roles of CCR7 for the Homing of Memory CD8+ T Cells into Their Survival Niches

Memory CD8+ T cells in the immune system are responsible for the removal of external Ags for a long period of time to protect against re-infection. Naïve to memory CD8+ T cell differentiation and memory CD8+ T cell maintenance require many different factors including local environmental factors. Thus, it has been suggested that the migration of memory CD8+ T cells into specific microenvironments alters their longevity and functions. In this review, we have summarized the subsets of memory CD8+ T cells based on their migratory capacities and described the niche hypothesis for their survival. In addition, the basic roles of CCR7 in conjunction with the migration of memory CD8+ T cells and recent understandings of their survival niches have been introduced. Finally, the applications of altering CCR7 signaling have been discussed.

Lymphatic Programing and Specialization in Hybrid Vessels

Building on a large body of existing blood vascular research, advances in lymphatic research have helped kindle broader investigations into vascular diversity and endothelial plasticity. While the endothelium of blood and lymphatic vessels can be distinguished by a variety of molecular markers, the endothelia of uniquely diverse vascular beds can possess distinctly heterogeneous or hybrid expression patterns. These expression patterns can then provide further insight on the development of these vessels and how they perform their specialized function. In this review we examine five highly specialized hybrid vessel beds that adopt partial lymphatic programing for their specialized vascular functions: the high endothelial venules of secondary lymphoid organs, the liver sinusoid, the Schlemm’s canal of the eye, the renal ascending vasa recta, and the remodeled placental spiral artery. We summarize the morphology and endothelial expression pattern of these vessels, compare them to each other, and interrogate their specialized functions within the broader blood and lymphatic vascular systems.

The new biology of PTCL-NOS and AITL: current status and future clinical impact

Peripheral T-cell lymphomas (PTCL) comprise a heterogeneous group of aggressive lymphoproliferative disorders almost all of which are associated with poor clinical outcomes. Angioimmunoblastic T-cell lymphoma (AITL) and some peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) have similarities to normal CD4⁺ T-cell subsets in their gene expression profiles. A cell of origin model is, therefore, emerging and is likely to be refined in the future. Follicular helper (Tfh) T cells are now established as the cell of origin of AITL and about 20% of PTCL-NOS. Sequencing studies have identified recurrent genetic alterations in epigenetic modifiers, T-cell receptor signalling pathway intermediates or RHOA, most commonly a specific mutation leading to RHOA G17V. While PTCL-NOS remains a diagnosis of exclusion, advances in genomics have identified subgroups expressing transcription factors TBX 21 (Th1-like origin) and GATA3 (Th2-like origin). These findings suggest new biomarkers and new therapeutic avenues including the hypomethylating agent azacytidine, or inhibitors of proximal T-cell receptor (TCR) signalling and potentially certain monoclonal antibodies. The advances over the past few years, therefore, prompt stratified medicine approaches to test biologically based treatments and determine the clinical utility of the new disease classifications.

Mechanisms of Tumor-Lymphatic Interactions in Invasive Breast and Prostate Carcinoma

During the last few years, diverse studies have shown that tumors can actively interact with the lymphatic system and promote metastases development. In order to examine the molecular mechanisms involved in this interaction, we co-cultured tumor and lymphatic endothelial cells (LEC) and subsequently analyzed the molecular alterations of LECs. Therefore, LECs were co-cultivated with either a highly or weakly metastatic breast cancer cell line using contact (mixture) and non-contact (transwell) co-cultures. mRNA profiles from LECs were subsequently analyzed for genes specifically induced by highly metastatic tumor cells (“metastatic specific”). Among the up-regulated “metastatic specific” genes, we found candidates involved in cell cycle, cell adhesion and motility (BST2, E-selectin, and HMMR), cytokines (CCL7, CXCL6, CXCL1, and CSF2) and factors of the complement system (C1R, C3, and CFB). Among the down-regulated genes, we detected the hyaluronan receptor STAB2, angiogenic factor apelin receptor (APLNR), and the glycosylation enzyme MAN1A1. In an additional prostate cancer co-culture model, we could confirm a “metastatic specific” upregulation of E-selectin and CCL7 in LECs after interaction with the prostate cancer cell lines LNCAP (highly metastatic) and DU145 (weakly metastatic). These data allowed us to identify a set of genes regulated in LECs during in vitro communication with cancer cells, which might subsequently facilitate lymphatic metastasis.

CCL21 Programs Immune Activity in Tumor Microenvironment

CCL21 promotes immune activity in the tumor microenvironment (TME) by colocalizing dendritic cells (DC) and T cells programing ectopic lymph node architectural structures that correlate with cancer prognosis. Innovative strategies to deliver CCL21 in cancer patients will reactivate the downregulated immune activity in the TME. Immune escape mechanisms are upregulated in the TME that promote tumor immune evasion. CCL21 combined with inhibition of dominant pathways of immune evasion will aid in the development of effective immunotherapy for cancer.

The Role of Nanovaccine in Cross-Presentation of Antigen-Presenting Cells for the Activation of CD8+ T Cell Responses

Explosive growth in nanotechnology has merged with vaccine development in the battle against diseases caused by bacterial or viral infections and malignant tumors. Due to physicochemical characteristics including size, viscosity, density and electrostatic properties, nanomaterials have been applied to various vaccination strategies. Nanovaccines, as they are called, have been the subject of many studies, including review papers from a material science point of view, although a mode of action based on a biological and immunological understanding has yet to emerge. In this review, we discuss nanovaccines in terms of CD8+ T cell responses, which are essential for antiviral and anticancer therapies. We focus mainly on the role and mechanism, with particular attention to the functional aspects, of nanovaccines in inducing cross-presentation, an unconventional type of antigen-presentation that activates CD8+ T cells upon administration of exogenous antigens, in dendritic cells followed by activation of antigen-specific CD8+ T cell responses. Two major intracellular mechanisms that nanovaccines harness for cross-presentation are described; one is endosomal swelling and rupture, and the other is membrane fusion. Both processes eventually allow exogenous vaccine antigens to be exported from phagosomes to the cytosol followed by loading on major histocompatibility complex class I, triggering clonal expansion of CD8+ T cells. Advancement of nanotechnology with an enhanced understanding of how nanovaccines work will contribute to the design of more effective and safer nanovaccines.

Mechanisms of Antiphospholipid Syndrome Induction: Role of NKT Cells

The review discusses the mechanisms of participation of natural killer T cells (NKT cells) in the induction of antiphospholipid antibodies (APA) that play a major pathogenetic role in the formation of antiphospholipid syndrome (APS), summarizes the data on APS pathogenesis, and presents modern concepts on the antibody formation involving follicular helper type II NK cells.

The Biophysics of Lymphatic Transport: Engineering Tools and Immunological Consequences

Lymphatic vessels mediate fluid flows that affect antigen distribution and delivery, lymph node stromal remodeling, and cell-cell interactions, to thus regulate immune activation. Here we review the functional role of lymphatic transport and lymph node biomechanics in immunity. We present experimental tools that enable quantitative analysis of lymphatic transport and lymph node dynamics in vitro and in vivo. Finally, we discuss the current understanding for how changes in lymphatic transport and lymph node biomechanics contribute to pathogenesis of conditions including cancer, aging, neurodegeneration, and infection.