Artery Tertiary Lymphoid Organs: Powerhouses of Atherosclerosis Immunity

The effect of carotid sinus neurectomy for carotid restenosis: a study protocol for a double-blinded and randomized controlled trial

BACKGROUND

Patients undergoing carotid endarterectomy (CEA) have a high restenosis rate, which increases the risk of stroke, and there is still a lack of effective treatment for restenosis. The cause of stenosis is related to local inflammatory reactions. Some basic studies have shown that the inflammatory response causing arterial stenosis is closely related to the nerve axons distributed in its outer membrane, and that removal of the nerve is effective in reducing the inflammatory response to prevent arterial stenosis. Therefore, we propose to design a randomized controlled trial to study whether disconnecting the carotid sinus nerve during a CEA operation can reduce carotid arterial restenosis.

METHOD/DESIGN

This study is a randomized, double-blind, single-center study. We will recruit 276 patients, who will be randomly divided into the experimental group and the control group. Based on the standard CEA operation, the operator will search for the carotid sinus nerve on the surface of the internal carotid artery and will entirely transect it in the experimental group. Both groups will be guided with the same postoperative treatment and will be followed up every 3 months for 3 years after the operation. The main indices observed will be the carotid restenosis rate, incidence and nature of carotid plaque, and carotid blood flow velocity. Other indices will be arrhythmia, blood pressure variability, and biomarkers of atherosclerosis, such as blood lipids, hypersensitive C-reactive protein (hs-CRP), homocysteine, and total bilirubin.

DISCUSSION

It is expected that carotid sinus nerve transection will significantly reduce the occurrence of restenosis after CEA, decrease the incidence of ischemic stroke, and realize the effective primary prevention of stroke.

TRIAL REGISTRATION

ChiCTR2300073652. Registered on July 18, 2023.

Disordered Balance of T-Cell Subsets in Arterial Tertiary Lymphoid Organs in Immunoglobulin G4-Related Vascular Disease

BACKGROUND

Arterial/aortic tertiary lymphoid organs (ATLOs), characterized by germinal centers, control local arterial immune responses. T follicular helper cells (Tfh), resident in germinal centers, regulate immunoglobulin production and germinal center development. They consist of Tfh1, Tfh2, and Tfh17 subsets. T follicular regulatory (Tfr) cells possess suppressive functions as regulatory T cells and migrate into germinal centers. Immunoglobulin G4 (IgG4)-related diseases manifest in vascular lesions as frequently formed inflammatory aneurysms (IgG4-related abdominal aortic aneurysm [IgG4-AAAs]). IgG4-AAAs contain several ATLOs.

METHODS AND RESULTS

We performed whole-slide immunohistochemical image analysis in surgical specimens of IgG4-AAAs (n=21), non-IgG4-related inflammatory AAAs (n=17), atherosclerotic AAAs (n=10), and Takayasu arteritis (n=5). IgG4-AAA was characterized by numerous, large, irregular-shaped ATLOs, and higher numbers of Tfr and Tfh2 cells than Tfh1 cells were present compared with others. The morphologic abnormalities (in number, area, and form) of ATLOs in IgG4-AAAs and the increased number of Tfr cells are closely related to the activity of IgG4-related diseases. All T-cell subsets were more enriched within ATLOs than outside ATLOs. In particular, an increase in Tfr cells in IgG4-AAAs was associated with ATLO formation. Increased Tfh17 cells were found in Takayasu arteritis, and atherosclerotic AAA and non-IgG4-related inflammatory AAAs were characterized by increased Tfh1 cells.

CONCLUSIONS

In the classification of vascular lesions, considering the imbalance in T-cell subsets, IgG4-AAA should be positioned as adventitial vasculitis with predominant Tfr and Tfh2 cells, accompanied by the abnormal appearance of ATLOs.

Cardiovascular Brain Circuits

The cardiovascular system is hardwired to the brain via multilayered afferent and efferent polysynaptic axonal connections. Two major anatomically and functionally distinct though closely interacting subcircuits within the cardiovascular system have recently been defined: The artery-brain circuit and the heart-brain circuit. However, how the nervous system impacts cardiovascular disease progression remains poorly understood. Here, we review recent findings on the anatomy, structures, and inner workings of the lesser-known artery-brain circuit and the better-established heart-brain circuit. We explore the evidence that signals from arteries or the heart form a systemic and finely tuned cardiovascular brain circuit: afferent inputs originating in the arterial tree or the heart are conveyed to distinct sensory neurons in the brain. There, primary integration centers act as hubs that receive and integrate artery-brain circuit-derived and heart-brain circuit-derived signals and process them together with axonal connections and humoral cues from distant brain regions. To conclude the cardiovascular brain circuit, integration centers transmit the constantly modified signals to efferent neurons which transfer them back to the cardiovascular system. Importantly, primary integration centers are wired to and receive information from secondary brain centers that control a wide variety of brain traits encoded in engrams including immune memory, stress-regulating hormone release, pain, reward, emotions, and even motivated types of behavior. Finally, we explore the important possibility that brain effector neurons in the cardiovascular brain circuit network connect efferent signals to other peripheral organs including the immune system, the gut, the liver, and adipose tissue. The enormous recent progress vis-à-vis the cardiovascular brain circuit allows us to propose a novel neurobiology-centered cardiovascular disease hypothesis that we term the neuroimmune cardiovascular circuit hypothesis.

Atherosclerosis and Inflammation: Insights from the Theory of General Pathological Processes

Recent advances have greatly improved our understanding of the molecular mechanisms behind atherosclerosis pathogenesis. However, there is still a need to systematize this data from a general pathology perspective, particularly with regard to atherogenesis patterns in the context of both canonical and non-classical inflammation types. In this review, we analyze various typical phenomena and outcomes of cellular pro-inflammatory stress in atherosclerosis, as well as the role of endothelial dysfunction in local and systemic manifestations of low-grade inflammation. We also present the features of immune mechanisms in the development of productive inflammation in stable and unstable plaques, along with their similarities and differences compared to canonical inflammation. There are numerous factors that act as inducers of the inflammatory process in atherosclerosis, including vascular endothelium aging, metabolic dysfunctions, autoimmune, and in some cases, infectious damage factors. Life-critical complications of atherosclerosis, such as cardiogenic shock and severe strokes, are associated with the development of acute systemic hyperinflammation. Additionally, critical atherosclerotic ischemia of the lower extremities induces paracoagulation and the development of chronic systemic inflammation. Conversely, sepsis, other critical conditions, and severe systemic chronic diseases contribute to atherogenesis. In summary, atherosclerosis can be characterized as an independent form of inflammation, sharing similarities but also having fundamental differences from low-grade inflammation and various variants of canonical inflammation (classic vasculitis).

Research progress on the active ingredients of traditional Chinese medicine in the intervention of atherosclerosis: A promising natural immunotherapeutic adjuvant

Atherosclerosis (AS) is a chronic inflammatory disease caused by disorders of lipid metabolism. Abnormal deposition of low-density lipoproteins in the arterial wall stimulates the activation of immune cells, including the adhesion and infiltration of monocytes, the proliferation and differentiation of macrophages and lymphocytes, and the activation of their functions. The complex interplay between immune cells coordinates the balance between pro- and anti-inflammation and plays a key role in the progression of AS. Therefore, targeting immune cell activity may lead to the development of more selective drugs with fewer side effects to treat AS without compromising host defense mechanisms. At present, an increasing number of studies have found that the active ingredients of traditional Chinese medicine (TCM) can regulate the function of immune cells in multiple ways to against AS, showing great potential for the treatment of AS and promising clinical applications. In this paper, we review the mechanisms of immune cell action in AS lesions and the potential targets and/or pathways for immune cell regulation by the active ingredients of TCM to promote the understanding of the immune system interactions of AS and provide a relevant basis for the use of active ingredients of TCM as natural adjuvants for AS immunotherapy.

Pathways linking aging and atheroprotection in Mif-deficient atherosclerotic mice

Atherosclerosis is a chronic inflammatory condition of our arteries and the main underlying pathology of myocardial infarction and stroke. The pathogenesis is age-dependent, but the links between disease progression, age, and atherogenic cytokines and chemokines are incompletely understood. Here, we studied the chemokine-like inflammatory cytokine macrophage migration inhibitory factor (MIF) in atherogenic Apoe^-/- mice across different stages of aging and cholesterol-rich high-fat diet (HFD). MIF promotes atherosclerosis by mediating leukocyte recruitment, lesional inflammation, and suppressing atheroprotective B cells. However, links between MIF and advanced atherosclerosis across aging have not been systematically explored. We compared effects of global Mif-gene deficiency in 30-, 42-, and 48-week-old Apoe^-/- mice on HFD for 24, 36, or 42 weeks, respectively, and in 52-week-old mice on a 6-week HFD. Mif-deficient mice exhibited reduced atherosclerotic lesions in the 30/24- and 42/36-week-old groups, but atheroprotection, which in the applied Apoe^-/- model was limited to lesions in the brachiocephalic artery and abdominal aorta, was not detected in the 48/42- and 52/6-week-old groups. This suggested that atheroprotection afforded by global Mif-gene deletion differs across aging stages and atherogenic diet duration. To characterize this phenotype and study the underlying mechanisms, we determined immune cells in the periphery and vascular lesions, obtained a multiplex cytokine/chemokine profile, and compared the transcriptome between the age-related phenotypes. We found that Mif deficiency promotes lesional macrophage and T-cell counts in younger but not aged mice, with subgroup analysis pointing toward a role for Trem2⁺ macrophages. The transcriptomic analysis identified pronounced MIF- and aging-dependent changes in pathways predominantly related to lipid synthesis and metabolism, lipid storage, and brown fat cell differentiation, as well as immunity, and atherosclerosis-relevant enriched genes such as Plin1, Ldlr, Cpne7, or Il34, hinting toward effects on lesional lipids, foamy macrophages, and immune cells. Moreover, Mif-deficient aged mice exhibited a distinct plasma cytokine/chemokine signature consistent with the notion that mediators known to drive inflamm'aging are either not downregulated or even upregulated in Mif-deficient aged mice compared with the corresponding younger ones. Lastly, Mif deficiency favored formation of lymphocyte-rich peri-adventitial leukocyte clusters. While the causative contributions of these mechanistic pillars and their interplay will be subject to future scrutiny, our study suggests that atheroprotection due to global Mif-gene deficiency in atherogenic Apoe^-/- mice is reduced upon advanced aging and identifies previously unrecognized cellular and molecular targets that could explain this phenotype shift. These observations enhance our understanding of inflamm'aging and MIF pathways in atherosclerosis and may have implications for translational MIF-directed strategies.

The Effect of Lymphangiogenesis in Transplant Arteriosclerosis

BACKGROUND

Transplant arteriosclerosis is a major complication in long-term survivors of heart transplantation. Increased lymph flow from donor heart to host lymph nodes has been reported to play a role in transplant arteriosclerosis, but how lymphangiogenesis affects this process is unknown.

METHODS

Vascular allografts were transplanted among various combinations of mice, including wild-type, Lyve1-CreERT2;R26-tdTomato, CAG-Cre-tdTomato, severe combined immune deficiency, Ccr2KO, Foxn1KO, and lghm/lghdKO mice. Whole-mount staining and 3-dimensional reconstruction identified lymphatic vessels within the grafted arteries. Lineage tracing strategies delineated the cellular origin of lymphatic endothelial cells. Adeno-associated viral vectors and a selective inhibitor were used to regulate lymphangiogenesis.

RESULTS

Lymphangiogenesis within allograft vessels began at the anastomotic sites and extended from preexisting lymphatic vessels in the host. Tertiary lymphatic organs were identified in transplanted arteries at the anastomotic site and lymphatic vessels expressing CCL21 (chemokine [C-C motif] ligand 21) were associated with these immune structures. Fibroblasts in the vascular allografts released VEGF-C (vascular endothelial growth factor C), which stimulated lymphangiogenesis into the grafts. Inhibition of VEGF-C signaling inhibited lymphangiogenesis, neointima formation, and adventitial fibrosis of vascular allografts. These studies identified VEGF-C released from fibroblasts as a signal stimulating lymphangiogenesis extending from the host into the vascular allografts.

CONCLUSIONS

Formation of lymphatic vessels plays a key role in the immune response to vascular transplantation. The inhibition of lymphangiogenesis may be a novel approach to prevent transplant arteriosclerosis.

Tertiary lymphoid tissues: a regional hub for kidney inflammation

Tertiary lymphoid tissues (TLTs) are inducible ectopic lymphoid tissues that develop at sites of chronic inflammation in nonlymphoid organs. As with lymph nodes, TLTs initiate adaptive immune responses and coordinate local tissue immunity. Although virtually ignored for decades, TLTs have recently received a great deal of attention for their ability to influence disease severity, prognosis and response to therapy in various diseases, including cancer, autoimmune disorders and infections. TLTs are also induced in kidneys of patients with chronic kidney diseases such as immunoglobulin A nephropathy and lupus nephritis. Nevertheless, TLTs in the kidney have not been extensively investigated and their mechanism of development, functions and clinical relevance remain unknown, mainly because of the absence of adequate murine kidney TLT models and limited availability of human kidney samples containing TLTs. We recently found that aged kidneys, but not young kidneys, exhibit multiple TLTs after injury. Interestingly, although they are a minor component of TLTs, resident fibroblasts in the kidneys diversify into several distinct phenotypes that play crucial roles in TLT formation. Furthermore, the potential of TLTs as a novel kidney injury/inflammation marker as well as a novel therapeutic target for kidney diseases is also suggested. In this review article we describe the current understanding of TLTs with a focus on age-dependent TLTs in the kidney and discuss their potential as a novel therapeutic target and kidney inflammation marker.

Differential regulation of lymphatic junctional morphology and the potential effects on cardiovascular diseases

The lymphatic vasculature provides an essential route to drain fluid, macromolecules, and immune cells from the interstitium as lymph, returning it to the bloodstream where the thoracic duct meets the subclavian vein. To ensure functional lymphatic drainage, the lymphatic system contains a complex network of vessels which has differential regulation of unique cell-cell junctions. The lymphatic endothelial cells lining initial lymphatic vessels form permeable "button-like" junctions which allow substances to enter the vessel. Collecting lymphatic vessels form less permeable "zipper-like" junctions which retain lymph within the vessel and prevent leakage. Therefore, sections of the lymphatic bed are differentially permeable, regulated in part by its junctional morphology. In this review, we will discuss our current understanding of regulating lymphatic junctional morphology, highlighting how it relates to lymphatic permeability during development and disease. We will also discuss the effect of alterations in lymphatic permeability on efficient lymphatic flux in health and how it may affect cardiovascular diseases, with a focus on atherosclerosis.

Excessive Adventitial and Perivascular Vascularisation Correlates with Vascular Inflammation and Intimal Hyperplasia

Albeit multiple studies demonstrated that vasa vasorum (VV) have a crucial importance in vascular pathology, the informative markers and metrics of vascular inflammation defining the development of intimal hyperplasia (IH) have been vaguely studied. Here, we employed two rat models (balloon injury of the abdominal aorta and the same intervention optionally complemented with intravenous injections of calciprotein particles) and a clinical scenario (arterial and venous conduits for coronary artery bypass graft (CABG) surgery) to investigate the pathophysiological interconnections among VV, myeloperoxidase-positive (MPO⁺) clusters, and IH. We found that the amounts of VV and MPO⁺ clusters were strongly correlated; further, MPO⁺ clusters density was significantly associated with balloon-induced IH and increased at calciprotein particle-provoked endothelial dysfunction. Likewise, number and density of VV correlated with IH in bypass grafts for CABG surgery at the pre-intervention stage and were higher in venous conduits which more frequently suffered from IH as compared with arterial grafts. Collectively, our results underline the pathophysiological importance of excessive VV upon the vascular injury or at the exposure to cardiovascular risk factors, highlight MPO⁺ clusters as an informative marker of adventitial and perivascular inflammation, and propose another mechanistic explanation of a higher long-term patency of arterial grafts upon the CABG surgery.

The adventitia in arterial development, remodeling, and hypertension

The adventitia receives input signals from the vessel wall, the immune system, perivascular nerves and from surrounding tissues to generate effector responses that regulate structural and mechanical properties of blood vessels. It is a complex and dynamic tissue that orchestrates multiple functions for vascular development, homeostasis, repair, and disease. The purpose of this review is to highlight recent advances in our understanding of the origins, phenotypes, and functions of adventitial and perivascular cells with particular emphasis on hypertensive vascular remodeling.

Impact of Non-Pharmacological Interventions on the Mechanisms of Atherosclerosis

Atherosclerosis remains the leading cause of mortality and morbidity worldwide characterized by the deposition of lipids and fibrous elements in the form of atheroma plaques in vascular areas which are hemodynamically overloaded. The global burden of atherosclerotic cardiovascular disease is steadily increasing and is considered the largest known non-infectious pandemic. The management of atherosclerotic cardiovascular disease is increasing the cost of health care worldwide, which is a concern for researchers and physicians and has caused them to strive to find effective long-term strategies to improve the efficiency of treatments by managing conventional risk factors. Primary prevention of atherosclerotic cardiovascular disease is the preferred method to reduce cardiovascular risk. Fasting, a Mediterranean diet, and caloric restriction can be considered useful clinical tools. The protective impact of physical exercise over the cardiovascular system has been studied in recent years with the intention of explaining the mechanisms involved; the increase in heat shock proteins, antioxidant enzymes and regulators of cardiac myocyte proliferation concentration seem to be the molecular and biochemical shifts that are involved. Developing new therapeutic strategies such as vagus nerve stimulation, either to prevent or slow the disease’s onset and progression, will surely have a profound effect on the lives of millions of people.

De-stressing plaques attenuates atherosclerosis progression

Atherogenesis is accompanied by formation of immune cell aggregates, so-called artery tertiary lymphoid organs (ATLOs), in the outermost layer of diseased arteries. In a recent study, Mohanta, Habenicht, and colleagues revealed that there are distinct interactions between ATLOs and the autonomous nervous system, which are critically implicated in atherosclerosis progression.

Single cell transcriptomics and TCR reconstruction reveal CD4 T cell response to MHC-II-restricted APOB epitope in human cardiovascular disease

Atherosclerosis is accompanied by a CD4 T cell response to apolipoprotein B (APOB). Major Histocompatibility Complex (MHC)-II tetramers can be used to isolate antigen-specific CD4 T cells by flow sorting. Here, we produce, validate and use an MHC-II tetramer, DRB1*07:01 APOB-p18, to sort APOB-p18-specific cells from peripheral blood mononuclear cell samples from 8 DRB1*07:01+ women with and without subclinical cardiovascular disease (sCVD). Single cell RNA sequencing showed that transcriptomes of tetramer+ cells were between regulatory and memory T cells in healthy women and moved closer to memory T cells in women with sCVD. TCR sequencing of tetramer+ cells showed clonal expansion and V and J segment usage similar to those found in regulatory T cells. These findings suggest that APOB-specific regulatory T cells may switch to a more memory-like phenotype in women with atherosclerosis. Mouse studies showed that such switched cells promote atherosclerosis.

Neuroimmune cardiovascular interfaces control atherosclerosis

Atherosclerotic plaques develop in the inner intimal layer of arteries and can cause heart attacks and strokes¹. As plaques lack innervation, the effects of neuronal control on atherosclerosis remain unclear. However, the immune system responds to plaques by forming leukocyte infiltrates in the outer connective tissue coat of arteries (the adventitia)^2-6. Here, because the peripheral nervous system uses the adventitia as its principal conduit to reach distant targets^7-9, we postulated that the peripheral nervous system may directly interact with diseased arteries. Unexpectedly, widespread neuroimmune cardiovascular interfaces (NICIs) arose in mouse and human atherosclerosis-diseased adventitia segments showed expanded axon networks, including growth cones at axon endings near immune cells and media smooth muscle cells. Mouse NICIs established a structural artery-brain circuit (ABC): abdominal adventitia nociceptive afferents^10-14 entered the central nervous system through spinal cord T₆-T₁₃ dorsal root ganglia and were traced to higher brain regions, including the parabrachial and central amygdala neurons; and sympathetic efferent neurons projected from medullary and hypothalamic neurons to the adventitia through spinal intermediolateral neurons and both coeliac and sympathetic chain ganglia. Moreover, ABC peripheral nervous system components were activated: splenic sympathetic and coeliac vagus nerve activities increased in parallel to disease progression, whereas coeliac ganglionectomy led to the disintegration of adventitial NICIs, reduced disease progression and enhanced plaque stability. Thus, the peripheral nervous system uses NICIs to assemble a structural ABC, and therapeutic intervention in the ABC attenuates atherosclerosis.

Tissue Clearing Approaches in Atherosclerosis

Recent advances in cardiovascular research have led to a more comprehensive understanding of molecular mechanisms of atherosclerosis. It has become apparent that the disease involves three layers of the arterial wall: the intima, the media, and a connective tissue coat termed the adventitia. It is also now appreciated that arteries are surrounded by adipose and neuronal tissues. In addition, adjacent to and within the adventitia, arteries are embedded in a loose connective tissue containing blood vessels (vasa vasora) and lymph vessels, artery-draining lymph nodes and components of the peripheral nervous system, including periarterial nerves and ganglia. During atherogenesis, each of these tissues undergoes marked structural and cellular alterations. We propose that a better understanding of these cell-cell and cell-tissue interactions may considerably advance our understanding of cardiovascular disease pathogenesis. Methods to acquire subcellular optical access to the intact tissues surrounding healthy and diseased arteries are urgently needed to achieve these aims. Tissue clearing is a landmark next-generation, three-dimensional (3D) microscopy technique that allows to image large-scale hitherto inaccessible intact deep tissue compartments. It allows for detailed reconstructions of arteries by a combination of labelling, clearing, advanced microscopies and other imaging and data-analysis tools. Here, we describe two distinct tissue clearing protocols; solvent-based modified three-dimensional imaging of solvent-cleared organs (3DISCO) clearing and another using aqueous-based 2,2'-thiodiethanol (TDE) clearing, both of which complement each other.

Combined Single-Cell RNA and Single-Cell α/β T Cell Receptor Sequencing of the Arterial Wall in Atherosclerosis

Although various pro- and anti-inflammatory T cell subsets have been observed in murine and human atherosclerosis, principal issues of T cell immunity remain unanswered: Is atherosclerosis progression critically affected by aberrant T cell responses? Are tolerance checkpoints compromised during atherosclerosis progression? Answers to these questions will determine if we are at the cusp of developing T cell-dependent therapeutic strategies. Rapid advances in single cell RNA sequencing (scRNA-seq) and single cell α/β T cell receptor (TCR) (scTCR) sequencing allows to address these issues in unprecedented ways. The majority of T cells recognize peptide antigen-MHC complexes presented by antigen-presenting cells which, in turn, trigger activation and proliferation (clonal expansion) of cognate TCR-carrying T cells. Thus, clonal expansion and their corresponding transcriptome are two similarly important sides of T cell immunity and both will-as hypothesized-affect the outcome of atherosclerosis. Here, we combined scRNA-seq and scTCR-seq in single cells. Moreover, we provide single T cell transcriptomes and TCR maps of three important tissues involved in atherosclerosis This approach is anticipated to address principal questions concerning atherosclerosis autoimmunity that are likely to pave the long sought way to T cell-dependent therapeutic approaches.

Self-Tolerance of Vascular Tissues Is Broken Down by Vascular Dendritic Cells in Response to Systemic Inflammation to Initiate Regional Autoinflammation

The correlation of infections with vascular autoinflammatory diseases such as vasculitis and atherosclerosis has been long recognized, and progressive inflammation with the formation of tertiary lymphoid organs in arterial adventitia intensively studied, the immunological basis of the nondiseased vasculatures that predispose to subsequent vascular autoimmunity during inflammation, however, is not well characterized. Here, we investigated the vascular immunity in situ of steady-state C57BL/6 mice and found that healthy vascular tissues contained a comprehensive set of immune cells with relatively higher proportion of innate components than lymphoid organs. Notably, a complete set of dendritic cell (DC) subsets was observed with monocyte-derived DCs (moDCs) constituting a major proportion; this is in contrast to moDCs being considered rare in the steady state. Interestingly, these vascular DCs constitutively expressed more suppressive factors with cDC1 for PD-L1 and moDCs for IL-10; this is concordant with the inhibitive phenotype of T cells in normal vascular tissues. The immunotolerant state of the vascular tissues, however, was readily eroded by systemic inflammation, demonstrated by the upregulation of proinflammatory cytokines and enhanced antigen presentation by vascular DCs to activate both cellular and humoral immunity in situ, which ultimately led to vascular destruction. Different vascular DC subsets elicited selective effects: moDCs were potent cytokine producers and B-cell activators, whereas cDCs, particularly, cDC1, were efficient at presenting antigens to stimulate T cells. Together, we unveil regional immunological features of vascular tissues to explain their dual facets under physiological versus pathological conditions for the better understanding and treatment of cardiovascular autoinflammation.

The Role of Lymphangiogenesis in Coronary Atherosclerosis

Lymphatic circulation, a one-way channel system independent of blood circulation, collects interstitial fluid in a blind-end way. Existing widely in various organs and tissues, lymphatic vessels play important roles in maintaining tissue fluid homeostasis, regulating immune function, and promoting lipid transport. Recent studies have shown clear evidence that lymphangiogenesis has a strong mutual effect on coronary atherosclerosis (AS). In this study, we focus on this topic, especially in the aspects of relevant ligand/receptor, inflammation, and adipose metabolism. For the moment, however, the role of lymphangiogenesis and remodeling in coronary AS still remains controversial. The studies of our group and accumulating published evidence show that the pathological remodeling of lymphatic vessels in coronary AS may have a negative effect, but normal functional lymphangiogenesis is probably beneficial to the regression of coronary AS. Thus, the conclusion of this review is that lymphatic vessel function rather than its quantity determines its influence in AS, which needs more evidence to support.

Key Chemokine Pathways in Atherosclerosis and Their Therapeutic Potential

The search to improve therapies to prevent or treat cardiovascular diseases (CVDs) rages on, as CVDs remain a leading cause of death worldwide. Here, the main cause of CVDs, atherosclerosis, and its prevention, take center stage. Chemokines and their receptors have long been known to play an important role in the pathophysiological development of atherosclerosis. Their role extends from the initiation to the progression, and even the potential regression of atherosclerotic lesions. These important regulators in atherosclerosis are therefore an obvious target in the development of therapeutic strategies. A plethora of preclinical studies have assessed various possibilities for targeting chemokine signaling via various approaches, including competitive ligands and microRNAs, which have shown promising results in ameliorating atherosclerosis. Developments in the field also include detailed imaging with tracers that target specific chemokine receptors. Lastly, clinical trials revealed the potential of various therapies but still require further investigation before commencing clinical use. Although there is still a lot to be learned and investigated, it is clear that chemokines and their receptors present attractive yet extremely complex therapeutic targets. Therefore, this review will serve to provide a general overview of the connection between various chemokines and their receptors with atherosclerosis. The different developments, including mouse models and clinical trials that tackle this complex interplay will also be explored.

Macrophage ontogeny and functional diversity in cardiometabolic diseases

Macrophages are the dominant immune cell types in the adipose tissue, the liver or the aortic wall and they were originally believed to mainly derived from monocytes to fuel tissue inflammation in cardiometabolic diseases. However, over the last decade the identification of tissue resident macrophages (trMacs) from embryonic origin in these metabolic tissues has provided a breakthrough in the field forcing to better comprehend macrophage diversity during pathological states. Infiltrated monocyte-derived macrophages (moMacs), similar to trMacs, adapt to the local metabolic environment that eventually shapes their functions. In this review, we will summarize the emerging versatility of macrophages in cardiometabolic diseases with a focus in the control of adipose tissue, liver and large vessels homeostasis.

Leukocyte Trafficking via Lymphatic Vessels in Atherosclerosis

In recent years, lymphatic vessels have received increasing attention and our understanding of their development and functional roles in health and diseases has greatly improved. It has become clear that lymphatic vessels are critically involved in acute and chronic inflammation and its resolution by supporting the transport of immune cells, fluid, and macromolecules. As we will discuss in this review, the involvement of lymphatic vessels has been uncovered in atherosclerosis, a chronic inflammatory disease of medium- and large-sized arteries causing deadly cardiovascular complications worldwide. The progression of atherosclerosis is associated with morphological and functional alterations in lymphatic vessels draining the diseased artery. These defects in the lymphatic vasculature impact the inflammatory response in atherosclerosis by affecting immune cell trafficking, lymphoid neogenesis, and clearance of macromolecules in the arterial wall. Based on these new findings, we propose that targeting lymphatic function could be considered in conjunction with existing drugs as a treatment option for atherosclerosis.

Alarmin-activated B cells accelerate murine atherosclerosis after myocardial infarction via plasma cell-immunoglobulin-dependent mechanisms

AIMS

Myocardial infarction (MI) accelerates atherosclerosis and greatly increases the risk of recurrent cardiovascular events for many years, in particular, strokes and MIs. Because B cell-derived autoantibodies produced in response to MI also persist for years, we investigated the role of B cells in adaptive immune responses to MI.

METHODS AND RESULTS

We used an apolipoprotein-E-deficient (ApoE-/-) mouse model of MI-accelerated atherosclerosis to assess the importance of B cells. One week after inducing MI in atherosclerotic mice, we depleted B cells using an anti-CD20 antibody. This treatment prevented subsequent immunoglobulin G accumulation in plaques and MI-induced accelerated atherosclerosis. In gain of function experiments, we purified spleen B cells from mice 1 week after inducing MI and transferred these cells into atherosclerotic ApoE-/- mice, which greatly increased immunoglobulin G (IgG) accumulation in plaque and accelerated atherosclerosis. These B cells expressed many cytokines that promote humoural immunity and in addition, they formed germinal centres within the spleen where they differentiated into antibody-producing plasma cells. Specifically deleting Blimp-1 in B cells, the transcriptional regulator that drives their terminal differentiation into antibody-producing plasma cells prevented MI-accelerated atherosclerosis. Alarmins released from infarcted hearts were responsible for activating B cells via toll-like receptors and deleting MyD88, the canonical adaptor protein for inflammatory signalling downstream of toll-like receptors, prevented B-cell activation and MI-accelerated atherosclerosis.

CONCLUSION

Our data implicate early B-cell activation and autoantibodies as a central cause for accelerated atherosclerosis post-MI and identifies novel therapeutic strategies towards preventing recurrent cardiovascular events such as MI and stroke.

Frequency of Efficient Circulating Follicular Helper T Cells Correlates with Dyslipidemia and WBC Count in Atherosclerosis

Background

The significance of cTfh cells and their subsets in atherosclerosis is not well understood. We measured the frequency of cTfh subsets in patients with different degrees of stenosis using flow-cytometry.

Methods

Participants included high (≥50%; n = 12) and low (<50%; n = 12) stenosis groups, as well as healthy controls (n = 6).

Results

The frequency of CCR7loPD-1hiefficient-cTfh was significantly higher in patients with high stenosis compared to healthy controls (p = 0.003) and correlated with low-density lipoprotein (LDL; p = 0.043), cholesterol (p = 0.043), triglyceride (p = 0.019), neutrophil count (p = 0.032), platelet count (p = 0.024), neutrophil/lymphocyte ratio (NLR; p = 0.046), and platelet/lymphocyte ratio (PLR; p = 0.025) in high stenosis group. The frequency of CCR7hiPD-1lo quiescent-cTfh was higher in healthy controls compared to the high-stenosis group (p = 0.001) and positively correlated with high-density lipoprotein (p = 0.046). The frequency of efficient-cTfh cells was correlated with platelet count (p = 0.043), NLR (p = 0.036), and PLR (p P = 0.035) in low-stenosis group, while that of quiescent-cTfh cells was negatively correlated with LDL (p = 0.034), cholesterol (p = 0.047), platelet count (p = 0.032), and PLR (p = 0.041).

Conclusion

High percentages of cTfh and efficient-cTfh cells in patients with advanced atherosclerosis and their correlation with dyslipidemia and white blood cell counts suggest an ongoing cTfh subset deviation, towards efficient phenotype in the milieu of inflammation and altered lipid profile. Efficient cTfh cells have an effector phenotype and could in turn contribute to atherosclerosis progression.

Partial recovery of senescence in circulating follicular helper T cells after Dasatinib treatment

Cellular senescence is an irreversible arrest of cell proliferation triggered by different stimuli, including DNA damage, telomere shortening and oncogenic stress. Senescent cells, by releasing the senescence-associated-secretory-phenotype (SASP), contribute to various diseases pathogenesis. Human atherosclerotic plaque contains cells with multiple markers of senescence that associate with disease severity. We characterized the frequency of senescent cTfh cells and genes expressions before and after treatment with Dasatinib in patients with different degrees of stenosis. Twelve high (≥50%), and twelve low (<50%) stenosis patients and six healthy controls were enrolled. The percentage of senescent CD3⁺CD4⁺CXCR5⁺CD153⁺CD57⁺ cells was significantly decreased in Dasatinib treated cells from individuals with low and high stenosis (P = 0.0007 and P = 0.0002, respectively). However, the frequency of total lymphocytes, CD3⁺ and CD4⁺ T cells were not significantly different between the groups before and after treatment. The expression levels of P53 (P = 0.0003 and P = 0.0001), P16 (P = 0.0005 and P = 0.0002), p21 (P = 0.0002 and P < 0.0001), SENEX (P = 0.0005 and P < 0.0001) and BCL-2 (P = 0.0005 and P = 0.0002) were decreased in PBMCs of low and high stenosis groups after treatment with Dasatinib, respectively. The percentage of senescent cTfh cells positively correlated with cholesterol (P = 0.034; r = 0.671), C-reactive protein (CRP) (P = 0.029; r = 0.707), Erythrocyte sedimentation rate (ESR) levels (P = 0.030; r = 0.598) and neutrophil counts (P = 0.021; r = 0.799) in patients with high stenosis. The decreased frequency of senescent cTfh cells and the expression levels of senescence genes after Dasatinib treatment in patients with atherosclerosis suggest a role for Dasatinib in partial clearance or rejuvenation of senescent cTfh cells, which may decrease inflammatory mediators and attenuate disease progression.

Vasculature-Associated Lymphoid Tissue: A Unique Tertiary Lymphoid Tissue Correlates With Renal Lesions in Lupus Nephritis Mouse Model

Lupus nephritis (LN) is a common complication in young patients and the most predominant cause of glomerulonephritis. Infiltrating immune cells and presence of immunocomplexes in the kidney are hallmarks of LN, which is closely associated with renal lesions (RLs). However, their regulatory mechanism in the kidney remains unclear, which is valuable for prevention of RL development. Here, we show the development of vasculature-associated lymphoid tissue (VALT) in LN, which is related to renal inflammatory cytokines, indicating that VALT is a unique tertiary lymphoid tissue. Transcriptomic analysis revealed different chemokines and costimulatory molecules for VALT induction and organization. Vascular and perivascular structures showed lymphoid tissue organization through lymphorganogenic chemokine production. Transcriptional profile and intracellular interaction also demonstrated antigen presentation, lymphocyte activity, clonal expansion, follicular, and germinal center activity in VALT. Importantly, VALT size was correlated with infiltrating immune cells in kidney and RLs, indicating its direct correlation with the development of RLs. In addition, dexamethasone administration reduced VALT size. Therefore, inhibition of VALT formation would be a novel therapeutic strategy against LN.

The XVth Banff Conference on Allograft Pathology the Banff Workshop Heart Report: Improving the diagnostic yield from endomyocardial biopsies and Quilty effect revisited

The XVth Banff Conference on Allograft Pathology meeting was held on September 23-27, 2019, in Pittsburgh, Pennsylvania, USA. During this meeting, two main topics in cardiac transplant pathology were addressed: (a) Improvement of endomyocardial biopsy (EMB) accuracy for the diagnosis of rejection and other significant injury patterns, and (b) the orphaned lesion known as Quilty effect or nodular endocardial infiltrates. Molecular technologies have evolved in recent years, deciphering pathophysiology of cardiac rejection. Diagnostically, it is time to integrate the histopathology of EMBs and molecular data. The goal is to incorporate molecular pathology, performed on the same paraffin block as a companion test for histopathology, to yield more accurate and objective EMB interpretation. Application of digital image analysis from hematoxylin and eosin (H&E) stain to multiplex labeling is another means of extracting additional information from EMBs. New concepts have emerged exploring the multifaceted significance of myocardial injury, minimal rejection patterns supported by molecular profiles, and lesions of arteriolitis/vasculitis in the setting of T cell-mediated rejection (TCMR) and antibody-mediated rejection (AMR). The orphaned lesion known as Quilty effect or nodular endocardial infiltrates. A state-of-the-art session with historical aspects and current dilemmas was reviewed, and possible pathogenesis proposed, based on advances in immunology to explain conflicting data. The Quilty effect will be the subject of a multicenter project to explore whether it functions as a tertiary lymphoid organ.

T Cells in Autoimmunity-Associated Cardiovascular Diseases

T cells are indisputably critical mediators of atherosclerotic cardiovascular disease (CVD), where they secrete pro-inflammatory cytokines that promote vascular pathology. Equally well-established is the fact that autoimmune diseases, which are mediated by autoreactive T cells, substantially increase the risk of developing CVD. Indeed, as immunomodulatory treatments have become more effective at treating end-organ pathology, CVD has become a leading cause of death in patients with autoimmune diseases. Despite this, investigators have only recently begun to probe the mechanisms by which autoreactive T cells promote CVD in the context of autoimmune diseases. T cells are best-studied in the pathogenesis of systemic vasculitides, where they react to self-antigen in the vessel wall. However, newer studies indicate that T cells also contribute to the increased CVD risk associated with lupus and rheumatoid arthritis. Given the central role of T-cell-derived cytokines in the pathogenesis of psoriasis, the role of these factors in psoriatic CVD is also under investigation. In the future, T cells are likely to represent major targets for the prevention and treatment of CVD in patients with autoimmune diseases.

Phylogenic Determinants of Cardiovascular Frailty, Focus on Hemodynamics and Arterial Smooth Muscle Cells

The evolution of the circulatory system from invertebrates to mammals has involved the passage from an open system to a closed in-parallel system via a closed in-series system, accompanying the increasing complexity and efficiency of life’s biological functions. The archaic heart enables pulsatile motion waves of hemolymph in invertebrates, and the in-series circulation in fish occurs with only an endothelium, whereas mural smooth muscle cells appear later. The present review focuses on evolution of the circulatory system. In particular, we address how and why this evolution took place from a closed, flowing, longitudinal conductance at low pressure to a flowing, highly pressurized and bifurcating arterial compartment. However, although arterial pressure was the latest acquired hemodynamic variable, the general teleonomy of the evolution of species is the differentiation of individual organ function, supported by specific fueling allowing and favoring partial metabolic autonomy. This was achieved via the establishment of an active contractile tone in resistance arteries, which permitted the regulation of blood supply to specific organ activities via its localized function-dependent inhibition (active vasodilation). The global resistance to viscous blood flow is the peripheral increase in frictional forces caused by the tonic change in arterial and arteriolar radius, which backscatter as systemic arterial blood pressure. Consequently, the arterial pressure gradient from circulating blood to the adventitial interstitium generates the unidirectional outward radial advective conductance of plasma solutes across the wall of conductance arteries. This hemodynamic evolution was accompanied by important changes in arterial wall structure, supported by smooth muscle cell functional plasticity, including contractility, matrix synthesis and proliferation, endocytosis and phagocytosis, etc. These adaptive phenotypic shifts are due to epigenetic regulation, mainly related to mechanotransduction. These paradigms actively participate in cardio-arterial pathologies such as atheroma, valve disease, heart failure, aneurysms, hypertension, and physiological aging.

Influenza A virus causes maternal and fetal pathology via innate and adaptive vascular inflammation in mice

Influenza infection during pregnancy is associated with increased maternal and perinatal complications. Here, we show that, during pregnancy, influenza infection leads to viral dissemination into the aorta, resulting in a peripheral “vascular storm” characterized by enhanced inflammatory mediators; the influx of Ly6C monocytes, neutrophils, and T cells; and impaired vascular function. The ensuing vascular storm induced hypoxia in the placenta and fetal brain and caused an increase in circulating cell free fetal DNA and soluble Flt1 release. We demonstrate that vascular dysfunction occurs in response to viral infection during pregnancy, which may explain the high rates of morbidity and mortality in pregnant dams, as well as the downstream perinatal complications associated with influenza infection.

Influenza A virus (IAV) infection during pregnancy causes severe maternal and perinatal complications, despite a lack of vertical transmission of IAV across the placenta. Here, we demonstrate a significant alteration in the maternal vascular landscape that underpins the maternal and downstream fetal pathology to IAV infection in mice. In IAV infection of nonpregnant mice, the local lung inflammatory response was contained to the lungs and was self-resolving, whereas in pregnant mice, virus dissemination to major maternal blood vessels, including the aorta, resulted in a peripheral "vascular storm," with elevated proinflammatory and antiviral mediators and the influx of Ly6C^low and Ly6C^high monocytes, plus neutrophils and T cells. This vascular storm was associated with elevated levels of the adhesion molecules ICAM and VCAM and the pattern-recognition receptors TLR7 and TLR9 in the vascular wall, resulting in profound vascular dysfunction. The sequalae of this IAV-driven vascular storm included placental growth retardation and intrauterine growth restriction, evidence of placental and fetal brain hypoxia, and increased circulating cell free fetal DNA and soluble Flt1. In contrast, IAV infection in nonpregnant mice caused no obvious alterations in endothelial function or vascular inflammation. Therefore, IAV infection during pregnancy drives a significant systemic vascular alteration in pregnant dams, which likely suppresses critical blood flow to the placenta and fetus. This study in mice provides a fundamental mechanistic insight and a paradigm into how an immune response to a respiratory virus, such as IAV, is likely to specifically drive maternal and fetal pathologies during pregnancy.

Dendritic Cells and T Cells, Partners in Atherogenesis and the Translating Road Ahead

Atherosclerosis is a chronic process associated with arterial inflammation, the accumulation of lipids, plaque formation in vessel walls, and thrombosis with late mortal complications such as myocardial infarction and ischemic stroke. Immune and inflammatory responses have significant effects on every phase of atherosclerosis. Increasing evidence has shown that both innate and adaptive “arms” of the immune system play important roles in regulating the progression of atherosclerosis. Accumulating evidence suggests that a unique type of innate immune cell, termed dendritic cells (DCs), play an important role as central instigators, whereas adaptive immune cells, called T lymphocytes, are crucial as active executors of the DC immunity in atherogenesis. These two important immune cell types work in pairs to establish pro-atherogenic or atheroprotective immune responses in vascular tissues. Therefore, understanding the role of DCs and T cells in atherosclerosis is extremely important. Here, in this review, we will present a complete overview, based on existing knowledge of these two cell types in the atherosclerotic microenvironment, and discuss some of the novel means of targeting DCs and T cells as therapeutic tactics for the treatment of atherosclerosis.

Adventitial matrix metalloproteinase production and distribution of immunoglobulin G4-related abdominal aortic aneurysms

Objective

IgG4-related diseases are systemic inflammatory fibrous lesions characterized by elevated serum IgG4 and infiltration of IgG4-positive plasmacytes. They can manifest in vascular lesions as frequently formed aneurysms with prominent thickening of the adventitia (IgG4-related abdominal aortic aneurysm; IgG4-AAA). Matrix metalloproteinases (MMPs) degrade the extracellular matrix, mainly in the tunica media, resulting in destruction of aortic structures to cause enlargement of the aneurysm. However, the expression of adventitial MMPs in IgG4-AAAs is poorly understood.

Methods

MMPs and MMPs-presenting cells in the adventitia of IgG4-AAAs (n = 19) of human surgical specimens were evaluated by immunohistochemistry and dual messenger RNA in situ hybridization. The results were compared with those from control groups of non-IgG4-related inflammatory AAA (n = 18), atherosclerotic AAA (aAAA; n = 11), and autopsy cases (n = 11). Preoperative serum MMPs levels of these groups were compared with the histologic data.

Results

Expression of MMP-9, MMP-2, and MMP-14 at the protein and messenger RNA levels in the adventitia was significantly higher in IgG4-AAAs than in controls. Other MMPs were scarce. The total number of MMP-9-positive cells was positively correlated with the diameter of the aneurysm (R = 0.461; P = .031), the adventitial thickness (R = 0.688; P < .001), and the number of IgG4-positive cells (R = 0.764; P < .001). Within lymphoid follicles, MMP-9-presenting cells were predominantly detected in large follicular dendritic cells, followed by histiocytes, fibroblasts, and plasmacytic dendritic cells. Outside lymphoid follicles, fibroblasts, and histiocytes mainly expressed MMP-9, and tissue dendritic cells also produced MMP-9. The levels of MMP-9 derived from follicular dendritic cells and histiocytes and plasmacytic dendritic cells outside lymphoid follicles were significantly higher in IgG4-AAA group than in other groups. Expression of adventitial MMP-2 and MMP-14 by histiocytes and fibroblasts was predominantly detected outside lymphoid follicles. Serum MMP-9 levels were significantly higher in IgG4-AAAs (835 ng/mL) than in controls, and correlated with serum IgG4 levels and the total numbers of adventitial MMP-9-positive cells, whereas serum MMP-2 levels did not differ among the three aneurysmal groups.

Conclusions

MMP-9 production in adventitial immune cells concerning lymphoid follicles was characteristic of IgG4-AAAs and might work in its activity with aneurysmal dilatation and adventitial thickening. Expressions of adventitial MMP-2 and MMP-14 were detected in histiocytes and fibroblasts outside lymphoid follicles, and were less concerned with the activity of IgG4-AAAs.

This retrospective multicenter study analyzed adventitial matrix metalloproteinases (MMPs) production in 19 patients with IgG4-related abdominal aortic aneurysms (AAAs) and 40 control cases. Adventitial MMP-9 production by various kinds of immune cells was increased in patients with IgG4-related AAAs and concerned with IgG4-AAA activity to cause aneurysmal progression and adventitial fibrosis, compared with aAAA. Serum MMP-9 levels reflected histologic MMP-9. Adventitial MMP-2 and MMP-14 were less concerned with IgG4-AAA activity. Thus, for IgG4-AAA patients, monitoring serum MMP-9 level might be the exacerbating factors related to adverse events during the treatment course.

Ectopic Lymphoid Organs and Immune-Mediated Diseases: Molecular Basis for Pharmacological Approaches

Chronic inflammation is the result a persistent increase in the expression of several proinflammatory pathways with impaired inflammatory resolution. Ectopic lymphoid organs (ELOs), untypical lymphoid annexes, emerge during chronic inflammation and contribute to the physiopathology of chronic inflammatory disorders. This review discusses the pathophysiological role of ELOs in the progression of immune-mediated inflammatory diseases (IMIDs), including multiple sclerosis (MS), rheumatoid arthritis (RA), inflammatory bowel disease (IBD), atherosclerosis, and Sjögren syndrome (SSj). The molecular pathways underlying the emergence of ELOs are of interest for the development of novel pharmacological approaches for the management of chronic inflammatory diseases.

Lymphatic Capillaries in Aging

The lymphatic system is responsible for fluid drainage from almost every organ in the body. It sustains tissue homeostasis and is also a central part of the immune system. With the discovery of cell-specific markers and transgenic mouse models, it has become possible to gain some insight into the developmental and functional roles of lymphatic endothelial cells (LECs). Only recently, a more direct regulatory role has been assigned to LECs in their functions in immunity responses and chronic diseases. Here, we discuss the changes occurring in aged lymphatic system and the role of lymphatic capillaries in some age-related diseases and experimental animal models.

Opportunities for an atherosclerosis vaccine: From mice to humans

Atherosclerosis, the major underlying cause of cardiovascular diseases (CVD), is the number one killer globally. The disease pathogenesis involves a complex interplay between metabolic and immune components. Although lipid-lowering drugs such as statins curb the risks associated with CVD, significant residual inflammatory risk remains. Substantial evidence from experimental models and clinical studies has established the role of inflammation and immune effector mechanisms in the pathogenesis of atherosclerosis. Several stages of the disease are affected by host-mediated antigen-specific adaptive immune responses that play either protective or proatherogenic roles. Therefore, strategies to boost an anti-atherogenic humoral and T regulatory cell response are emerging as preventative or therapeutic strategies to lowering inflammatory residual risks. Vaccination holds promise as an efficient, durable and relatively inexpensive approach to induce protective adaptive immunity in atherosclerotic patients. In this review, we discuss the status and opportunities for a human atherosclerosis vaccine. We describe (1) some of the immunomodulatory therapeutic interventions tested in atherosclerosis (2) the immune targets identified in pre-clinical and clinical investigations (3) immunization strategies evaluated in animal models (4) past and ongoing clinical trials to examine the safety and efficacy of human atherosclerosis vaccines and (5) strategies to improve and optimize vaccination in humans (antigen selection, formulation, dose and delivery).

Low frequency of IL-10+ B cells in patients with atherosclerosis is related with inflammatory condition

Background and aims

B cells involvement in animal models of atherosclerosis has been unequivocally established. However, the role of these cells in patients with atherosclerosis is almost unknown. Besides the production of antibodies, B cells can also exhibit regulatory functions mainly through IL-10. Here, we characterized human B cell subsets, their production of IL-10 in patients with atherosclerosis and their potential association with inflammation.

Methods

Patients with confirmed atherosclerotic events and controls with low cardiovascular risk were included. B cells subsets were determined in mononuclear cells (PBMC) using flow cytometry. PBMC were cultured ex vivo (5 h) and in vitro (48 h) to determine IL-10⁺ B cells and in some cases TNF-α⁺ and IFN-γ⁺ CD4⁺ T cells. The inflammatory state of the participants was determined through high sensitivity C reactive protein levels.

Results

Increase in percentage and number of plasmablasts was observed in patients with atherosclerosis compared with controls. A decreased frequency of IL-10⁺ B cells was observed in patients, both in ex vivo and in vitro cultures. This decrease was detected in transitional, memory, and plasmablast subsets. Interestingly, the reduction of IL-10⁺ B cells negatively and significantly correlated with the inflammatory condition of the studied subjects and associated with an increased frequency of TNF-α⁺ and IFN-γ⁺ CD4⁺ T cells. The blockade of IL-10R did not show further effect in T cells activation.

Conclusions

There is an association between the inflammatory state and a reduction of IL-10⁺ B cells that could contribute to the development of atherosclerosis.

HDL and Reverse Cholesterol Transport

Cardiovascular disease, with atherosclerosis as the major underlying factor, remains the leading cause of death worldwide. It is well established that cholesterol ester-enriched foam cells are the hallmark of atherosclerotic plaques. Multiple lines of evidence support that enhancing foam cell cholesterol efflux by HDL (high-density lipoprotein) particles, the first step of reverse cholesterol transport (RCT), is a promising antiatherogenic strategy. Yet, excitement towards the therapeutic potential of manipulating RCT for the treatment of cardiovascular disease has faded because of the lack of the association between cardiovascular disease risk and what was typically measured in intervention trials, namely HDL cholesterol, which has an inconsistent relationship to HDL function and RCT. In this review, we will summarize some of the potential reasons for this inconsistency, update the mechanisms of RCT, and highlight conditions in which impaired HDL function or RCT contributes to vascular disease. On balance, the evidence still argues for further research to better understand how HDL functionality contributes to RCT to develop prevention and treatment strategies to reduce the risk of cardiovascular disease.

Basics of Inducible Lymphoid Organs

Tertiary lymphoid organs (TLOs), also known as inducible lymphoid organs, tertiary lymphoid structures, tertiary lymphoid tissues, or ectopic lymphoid organs are accumulations of cells in chronic inflammation that have been observed in most tissues in autoimmunity, infection, and cancer in mouse and man. They share many properties with secondary lymphoid organs (SLOs), particularly lymph nodes, with regard to cellular composition, function, and regulation. TLOs include T and B cells, dendritic cells, follicular dendritic cells, and many other stromal cells, and high endothelial venules (HEVs) and lymphatic vessels. They serve as sites of antigen presentation and tolerance induction; they are harmful in autoimmunity and can be both harmful and beneficial in cancer. SLO induction in ontogeny is mediated by interactions of several cell types, including CD4+ CD3- lymphoid tissue inducer (LTi) RORγt+ cells that express LTαβ and interact with mesenchymal lymphoid tissue organizer (LTo) FAP+ cells in the presence of lymphatic and blood vessels. A variety of inducer cells initiate TLOs, including bona fide LTi cells, T cells, B cells, and NK cells. The mesenchymal organizer cells are less well characterized but can include FAP+ cells. Current challenges include identification of methods to inhibit TLOs in autoimmunity without affecting SLOs, and enhancement of TLOs for defense against tumors.

Recent Developments in Vascular Adventitial Pathobiology: The Dynamic Adventitia as a Complex Regulator of Vascular Disease

The adventitia, the outer layer of the blood vessel wall, may be the most complex layer of the wall and may be the master regulator of wall physiology and pathobiology. This review proposes a major shift in thinking to apply a functional lens to the adventitia rather than only a structural lens. Human and experimental in vivo and in vitro studies show that the adventitia is a dynamic microenvironment in which adventitial and perivascular adipose tissue cells initiate and regulate important vascular functions in disease, especially intimal hyperplasia and atherosclerosis. Although well away from the blood-wall interface, where much pathology has been identified, the adventitia has a profound influence on the population of intimal and medial endothelial, macrophage, and smooth muscle cell function. Vascular injury and dysfunction of the perivascular adipose tissue promote expansion of the vasa vasorum, activation of fibroblasts, and differentiation of myofibroblasts. This regulates further biologic processes, including fibroblast and myofibroblast migration and proliferation, inflammation, immunity, stem cell activation and regulation, extracellular matrix remodeling, and angiogenesis. A debate exists as to whether the adventitia initiates disease or is just an important participant. We describe a mechanistic model of adventitial function that brings together current knowledge and guides the design of future investigations to test specific hypotheses on adventitial pathobiology.

2019 Russell Ross Memorial Lecture in Vascular Biology: B Lymphocyte-Mediated Protective Immunity in Atherosclerosis

Atherosclerosis-the major underlying pathology of cardiovascular disease-is characterized by accumulation and subsequent oxidative modification of lipoproteins within the artery wall, leading to inflammatory cell infiltration and lesion formation that can over time result in arterial stenosis, ischemia, and downstream adverse events. The contribution of innate and adaptive immunity to atherosclerosis development is well established, and B cells have emerged as important modulators of both pro- and anti-inflammatory effects in atherosclerosis. Murine B cells can broadly be divided into 2 subsets: (1) B-2 cells, which are bone marrow derived and include conventional follicular and marginal zone B cells, and (2) B-1 cells, which are largely fetal liver derived and persist in adults through self-renewal. B-cell subsets are developmentally, functionally, and phenotypically distinct with unique subset-specific contributions to atherosclerosis development. Mechanisms whereby B cells regulate vascular inflammation and atherosclerosis will be discussed with a particular emphasis on B-1 cells. B-1 cells have a protective role in atherosclerosis that is mediated in large part by IgM antibody production. Accumulating evidence over the last several years has pointed to a previously underappreciated heterogeneity in B-1 cell populations, which may have important implications for understanding atherosclerosis development and potential targeted therapeutic approaches. This heterogeneity within atheroprotective innate B-cell subsets will be highlighted.

Chronic Inflammation: A Common Promoter in Tertiary Lymphoid Organ Neogenesis

Tertiary lymphoid organs (TLOs) frequently develop locally in adults in response to non-resolving inflammation. Chronic inflammation leads to the differentiation of stromal fibroblast cells toward lymphoid tissue organizer-like cells, which interact with lymphotoxin α1β2+ immune cells. The interaction initiates lymphoid neogenesis by recruiting immune cells to the site of inflammation and ultimately leads to the formation of TLOs. Mature TLOs harbor a segregated T-cell zone, B-cell follicles with an activated germinal center, follicular dendritic cells, and high endothelial venules, which architecturally resemble those in secondary lymphoid organs. Since CXCL13 and LTα₁β₂ play key roles in TLO neogenesis, they might constitute potential biomarkers of TLO activity. The well-developed TLOs actively regulate local immune responses and influence disease progression, and they are thereby regarded as the powerhouses of local immunity. In this review, we recapitulated the determinants for TLOs development, with great emphasis on the fundamental role of chronic inflammation and tissue-resident stromal cells for TLO neogenesis, hence offering guidance for therapeutic interventions in TLO-associated diseases.

Cytokines in heart failure

The natural history of heart failure (HF) is not linear, because changes in the heart structure and function start long before the disease becomes clinically evident. Many different cytokines originating from intracardiac tissues (cardiomyocytes, cardiac endothelial cells, cardiac fibroblasts, and cardiac infiltrated immune cells) or extracardiac tissues (adipose tissue, gut, and lymphoid organs) have been identified in HF. Because the levels of circulating cytokines correlate with the development and severity of HF, these mediators may have both pathophysiological importance, through their ability to modulate inflammation, myocyte stress/stretch, myocyte injury and apoptosis, fibroblast activation and extracellular matrix remodeling, and utility as clinical predictive biomarkers. A greater understanding of the mechanisms mediated by the multifaceted network of cytokines, leading to distinct HF phenotypes (HF with reduced or preserved ejection fraction), is urgently needed for the development of new treatment strategies. In this chapter, all these issues were thoroughly discussed, pointing on the practical considerations concerning the clinical use of the cytokines as prognostic biomarkers and potential therapeutic targets in HF.

Adipose Tissue: A Tertiary Lymphoid Organ: Does It Change with Age?

In this manuscript, we summarize published results showing that obesity and aging are inflammatory conditions associated with serious health problems, increased risk for disease and death. We show that fat mass increases with age and represents a major contributor to insulin resistance and the metabolic syndrome. We summarize the effects of age on the adipose tissue (AT), related to the abundance, distribution, cellular composition, endocrine signaling and function of the tissue. The AT is an immunological tissue, with several hallmarks of innate and adaptive immune responses. We show that in both mice and humans, the AT is heavily infiltrated by immune cells that have receptors for pro-inflammatory cytokines and chemokines secreted by the adipocytes and also by the immune cells that have infiltrated the AT. We also show that the AT provides an environment for the secretion of IgG antibodies with anti-self (autoimmune) reactivity. As we have previously shown, this is due to the release of self antigens following cell death due to hypoxia, as well as to the expression of activation-induced cytidine deaminase, the enzyme of class switch recombination, and the transcription factor T-bet by the resident B cells, which also express the membrane marker CD11c, both involved in the production of autoimmune IgG antibodies. We show data in support of the AT as a tertiary lymphoid organ (TLO), showing the examples of TLOs that develop within the AT, such as fat-associated lymphoid clusters and milky spots, as well as artery TLOs that develop in the adventitia areas of the aorta.

Vascular Smooth Muscle Cells Contribute to Atherosclerosis Immunity

Vascular smooth muscle cells (VSMCs) constitute the major cells in the media layer of arteries, and are critical to maintain the integrity of the arterial wall. They participate in arterial wall remodeling, and play important roles in atherosclerosis throughout all stages of the disease. Studies demonstrate that VSMCs can adopt numerous phenotypes depending on inputs from endothelial cells (ECs) of the intima, resident cells of the adventitia, circulating immune cells, hormones, and plasma lipoproteins. This plasticity allows them to perform multiple tasks in physiology and disease. In this minireview, we focus on a previously underappreciated activity of VSMCs, i.e., their impact on atherosclerosis immunity via formation of artery tertiary lymphoid organs (ATLOs).

Immunity in cancer and atherosclerosis

Cancer and cardiovascular diseases have been classified as non-communicable diseases for decades. Both diseases have characteristics of immune reactions, which are principally identical, but differing in important aspects. The aim of this communication is to highlight new approaches to immune processes involved in both types of diseases.

A Novel Triple-Cell Two-Dimensional Model to Study Immune-Vascular Interplay in Atherosclerosis

Atherosclerosis is a complex inflammatory pathology underpinning cardiovascular diseases (CVD), which are the leading cause of death worldwide. The interplay between vascular stromal cells and immune cells is fundamental to the progression and outcome of atherosclerotic disease, however, the majority of in vitro studies do not consider the implications of these interactions and predominantly use mono-culture approaches. Here we present a simple and robust methodology involving the co-culture of vascular endothelial (ECs) and smooth muscle cells (SMCs) alongside an inflammatory compartment, in our study containing THP-1 macrophages, for studying these complex interactions. Using this approach, we demonstrate that the interaction between vascular stromal and immune cells produces unique cellular phenotypes and soluble mediator profiles not observed in double-cell 2D cultures. Our results highlight the importance of cellular communication and support the growing idea that in vitro research must evolve from mono-culture systems to provide data more representative of the multi-cellular environment found in vivo. The methodology presented, in comparison with established approaches, has the advantage of being technically simple whilst enabling the isolation of pure populations of ECs, SMCs and immune cells directly from the co-culture without cell sorting. The approach described within would be applicable to those studying mechanisms of vascular inflammation, particularly in relation to understanding the impact cellular interaction has on the cumulative immune-vascular response to atherogenic or inflammatory stimuli.

Identification of key genes and pathways contributing to artery tertiary lymphoid organ development in advanced mouse atherosclerosis

Atherosclerosis is a leading cause of mortality worldwide. Artery tertiary lymphoid organ (ATLO) neogenesis is affected by abdominal aorta atherosclerosis, which may lead to an immune response. The present study obtained microarray data to investigate the gene expression differences underlying the potential pathogenesis of atherosclerosis and to elucidate the mechanisms underlying ATLO development. Microarray studies of the aorta, plaques, adventitia, blood, spleen, renal lymph nodes and ATLO were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified in aorta clusters and ATLO clusters. Kyoto Encyclopedia of Genes and Genomes enrichment and Gene Ontology (GO) analyses were conducted to predict the biological functions of DEGs. The results demonstrated that interleukin 7 receptor (Il7r), C‑X‑C motif chemokine ligand (Cxcl)16, Cxcl13, Cxcl12, C‑C motif chemokine receptor 2, C‑C motif chemokine ligand (Ccl)8, Ccl5 and Ccl12 may function through pathways associated with 'cytokine‑cytokine receptor interaction' and 'chemokine signaling pathway' in ATLO. Gene expression alterations were validated by reverse transcription‑quantitative polymerase chain reaction. Il7r appeared to be the central gene involved in these events, and chemokines and/or chemokine receptors were visualized by GO enrichment. A protein‑protein interaction network was constructed, which suggested that Il7r had a core function in all clusters. Taken together, the results indicated that Il7r upregulation may serve an important role in ATLO development via 'cytokine‑cytokine receptor interaction' and 'chemokine signaling pathway'. This may provide novel perspectives for understanding ATLO development and the regulation of the immune response in atherosclerosis.