Lymphatic and Immune Cell Cross-Talk Regulates Cardiac Recovery After Experimental Myocardial Infarction

Objective: Lymphatics play an essential pathophysiological role in promoting fluid and immune cell tissue clearance. Conversely, immune cells may influence lymphatic function and remodeling. Recently, cardiac lymphangiogenesis has been proposed as a therapeutic target to prevent heart failure after myocardial infarction (MI). We investigated the effects of gene therapy to modulate cardiac lymphangiogenesis post-MI in rodents. Second, we determined the impact of cardiac-infiltrating T cells on lymphatic remodeling in the heart. Approach and Results: Comparing adenoviral versus adeno-associated viral gene delivery in mice, we found that only sustained VEGF (vascular endothelial growth factor)-C(C156S)therapy, achieved by adeno-associated viral vectors, increased cardiac lymphangiogenesis, and led to reduced cardiac inflammation and dysfunction by 3 weeks post-MI. Conversely, inhibition of VEGF-C/-D signaling, through adeno-associated viral delivery of soluble VEGFR3 (vascular endothelial growth factor receptor 3), limited infarct lymphangiogenesis. Unexpectedly, this treatment improved cardiac function post-MI in both mice and rats, linked to reduced infarct thinning due to acute suppression of T-cell infiltration. Finally, using pharmacological, genetic, and antibody-mediated prevention of cardiac T-cell recruitment in mice, we discovered that both CD4(+)and CD8(+)T cells potently suppress, in part through interferon-gamma, cardiac lymphangiogenesis post-MI. Conclusions: We show that resolution of cardiac inflammation after MI may be accelerated by therapeutic lymphangiogenesis based on adeno-associated viral gene delivery of VEGF-C-C156S. Conversely, our work uncovers a major negative role of cardiac-recruited T cells on lymphatic remodeling. Our results give new insight into the interconnection between immune cells and lymphatics in orchestration of cardiac repair after injury.Peer reviewe

Cardiac lymphatics in health and disease

The lymphatic vasculature, which accompanies the blood vasculature in most organs, is indispensable in the maintenance of tissue fluid homeostasis, immune cell trafficking, and nutritional lipid uptake and transport, as well as in reverse cholesterol transport. In this Review, we discuss the physiological role of the lymphatic system in the heart in the maintenance of cardiac health and describe alterations in lymphatic structure and function that occur in cardiovascular pathology, including atherosclerosis and myocardial infarction. We also briefly discuss the role that immune cells might have in the regulation of lymphatic growth (lymphangiogenesis) and function. Finally, we provide examples of how the cardiac lymphatics can be targeted therapeutically to restore lymphatic drainage in the heart to limit myocardial oedema and chronic inflammation.Peer reviewe

Therapeutic vascular growth in the heart

International audienceDespite tremendous efforts in preclinical research over the last decades, the clinical translation of therapeutic angiogenesis to grow stable and functional blood vessels in patients with ischemic diseases continues to prove challenging. In this mini review, we briefly present the current main approaches applied to improve pro-angiogenic therapies. Specific examples from research on therapeutic cardiac angiogenesis and arteriogenesis will be discussed, and finally some suggestions for future therapeutic developments will be presented

Does anti-VEGF bevacizumab improve survival in experimental sepsis?

International audienceIn a previous issue of Critical Care, Jeong et al. reported a beneficial effect of bevacizumab (Bev), the first humanized vascular endothelial growth factor (VEGF)-neutralizing antibody, on vascular permeabil-ity and mortality in a murine model of sepsis [1]. VEGF has been associated with mortality during sepsis [2], and the administration of its natural antagonist improved survival in experimental sepsis [3]. Jeong et al. demonstrated that Bev reduced mortality in sepsis induced either by cecal ligature puncture (CLP) or by endotoxemia. Despite promising experimental data, no other study has yet confirmed these results. A clinical study was planned to evaluate Bev administration in critically ill patients but it was withdrawn before enrolment (NCT01063010). Thus, we aimed to reassess the potential benefit of Bev during experimental sepsis. After approval by the Haute-Normandie ethics committee (number 8092), male C57Bl6 mice received intraperitoneal NaCl (control) or Bev (0.5 mg/kg) immediately before CLP (n = 15/group), performed as described previously [4]. Briefly, the cecum was ligated (75% of total length) and punctioned bilaterally with a 21G needle. Topical lidocaïne (2%) was applied and mice received a sub-cutaneous administration of the antibiotic ofloxacine (30 mg/kg), the analgesic tramadol (40 mg/kg), and NaCl (30 ml/kg). Survival was evaluated twice per day for 10 days and analyzed through a log-rank test. No significant difference in mortality was observed between the Bev and control groups (36 versus 27% at day 10, p = 0.64). To overcome any non-optimal effect linked to the route of administration, and also to better mimic clinical use, we repeated the experiments with intravenous injection of Bev before surgery (n = 8/ group). Again, we did not observe any effect on mortality compared to CLP controls (42 versus 37% at day 10, p = 0.74). Pooling the data between experiments (Bev treatment either IP or IV versus controls; n = 23/group) also did not show any statistical difference (38 versus 31%, p = 0.56; Fig. 1). Even if our experimental procedure slightly varies, notably regarding the severity of sepsis, with a larger puncture site, and the use of intravenous route in some of the mice, these results contradict those described by Jeong et al. The absence of replication of their results may be surprising, notably regarding the suspected effects of the VEGF pathways in sepsis. Although we cannot identify the origin of this contradiction, the absence of new publications on this topic, in association with our negative results, raises the question of the clinical rational of anti-VEGF treatment in septic patients

Le système lymphatique cardiaque

International audience> Le système lymphatique est un réseau vas-culaire responsable du transport des graisses intestinales. Il participe à la surveillance immune et permet le maintien de l'homéostasie tissu-laire. Malgré un grand nombre d'évidences mon-trant l'importance des vaisseaux lymphatiques dans les maladies cardiovasculaires, le rôle des vaisseaux lymphatiques cardiaques n'a été que très peu étudié. En condition physiologique, le système lymphatique cardiaque régule dynami-quement le drainage des fluides interstitiels vers les ganglions médiastinaux afin de maintenir l'homéostasie du tissu cardiaque et de prévenir la formation d'un oedème. Après un infarctus du myocarde, les vaisseaux lymphatiques du coeur ischémique perdent leur fonction et contribuent au développement d'un oedème myocardique chronique qui aggrave la fibrose et la dysfonc-tion cardiaque. La stimulation de la lymphan-giogenèse cardiaque, fondée sur la délivrance de facteurs de croissance lymphangiogéniques comme le VEGF-C, pourrait représenter une nou-velle stratégie thérapeutique pour améliorer la fonction cardiaque. Cette revue met en évidence la chronologie des principales découvertes asso-ciées au développement et à la fonction lympha-tique cardiaque. < captés par des cellules présentatrices d'antigènes (CPA) afin d'initier des réponses immunitaires spécifiques contre des particules qui pour-raient être pathogènes (Figure 1) [3]. Les capillaires lymphatiques sont présents dans la peau et dans la plupart des organes internes, à l'exception de la moelle osseuse et des tissus avasculaires comme le cartilage, la cornée et l'épiderme. Dans l'intestin, les vaisseaux lymphatiques ont été initialement nom-més « veines blanches » en raison de leur coloration blanche observée en phase postprandiale dans la région mésentérique. Ils jouent un rôle primordial dans l'absorption des lipides intestinaux ; ils sont encore appelés « lactés » ou « lactéaux », en raison de cette particularité [4]. Majoritairement présents dans les villosités de l'intestin grêle, les vaisseaux lymphatiques sont à l'origine de l'absorption des lipides alimentaires, libérés sous la forme de chylomicrons par les entéro-cytes (Figure 1). Les vaisseaux lymphatiques jouent également un rôle important dans le transport réverse du cholestérol [5, 6]. La composition protéique de la lymphe est équivalente à celle du fluide inters-titiel qui est similaire, mais généralement moins concentrée, à celle du plasma sanguin, à l'exception de la lymphe intestinale qui contient une grande quantité de lipides intestinaux [7]. Cette lymphe est une émulsion trouble et laiteuse, souvent appelée « chyle ». Le drainage lymphatique peut être considérablement modifié à la suite d'une infection, d'un traumatisme, d'une chirurgie, d'une transplantation, d'un traitement, ou d'une maladie veineuse ou congénitale [8, 9]. La lymphangiogenèse, processus dirigeant la croissance de nou-veaux vaisseaux lymphatiques, apparaît au cours du développement embryonnaire. Elle se met en place à partir de bourgeonnements du système sanguin [1]. Elle est également impliquée dans de nombreux états pathologiques (Figure 1)

Progenitor Cell Mobilizing Treatments Prevent Experimental Transplant Arteriosclerosis

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Heart Rate Reduction Induced by the If Current Inhibitor Ivabradine Improves Diastolic Function and Attenuates Cardiac Tissue Hypoxia

International audienceAims: Enhanced heart rate (HR) is a compensatory mechanism in chronic heart failure (CHF), preserving cardiac output, but at the cost of increased left ventricular (LV) oxygen consumption and impaired diastolic function. The HR reduction (HRR) induced by the If current inhibitor ivabradine prevents LV systolic dysfunction in CHF, but whether HRR improves LV diastolic function is unknown. Methods: LV diastolic function and remodeling were assessed in rats with CHF after coronary ligation after long-term (90 days, starting 7 days after ligation) and delayed short-term (4 days, starting 93 days after ligation) ivabradine treatment (10 mg$kg −1$d −1). Results: Long-and short-term HRR reduced LV end-diastolic pressure, LV relaxation, and LV end-diastolic pressure-volume relation. Simultaneously, LV hypoxia-inducible factor-1a expression was reduced. Long-term and, to a more marked extent, short-term HRR increased endothelial cell proliferation, associated after long-term HRR with the prevention of CHF-related LV capillary rarefaction. Long-term and, to a lesser extent, short-term HRR increased endothe-lial nitric oxide synthase expression, associated after long-term HRR with improved nitric oxide-dependent coronary vasodilatation. Conclusions: Long-term HRR induced by ivabradine improves diastolic LV function probably involving attenuated hypoxia, reduced remodeling, and/or preserved nitric oxide bioavailability, resulting from processes triggered early after HRR initiation: angiogenesis and/or preservation of endothelial nitric oxide synthase expression

Role of M2-like macrophage recruitment during angiogenic growth factor therapy

International audienceTherapeutic angiogenesis has yet to fulfill its promise for the clinical treatment of ischemic diseases. Given the impact of macrophages during pathophysiological angiogenesis, we asked whether macrophages may similarly modulate vascular responses to targeted angiogenic therapies. Mouse matrigel plug assay and rat myocardial infarction (MI) model were used to assess angiogenic therapy with either VEGF-A or FGF-2 with HGF (F+H) delivered locally via albumin-alginate microcapsules. The infiltration of classical M1-type and alternative M2-like macrophages was assessed. Clodronate was used to prevent macrophage recruitment, and the VEGFR2 blocking antibody, DC101, to prevent VEGF-A signaling. At 3 weeks after matrigel implantation, the combination therapy (F+H) led to increased total, and specifically M2-like, macrophage infiltration versus control and VEGF-A plugs, correlating with the angiogenic response. In contrast, VEGF-A preferential recruited M1-type macrophages. In agreement with a direct role of M2-like macrophages in F+H-induced vessel growth, clodronate radically decreased angiogenesis. Further, DC101 reduced F+H-induced angiogenesis, without altering macrophage infiltration, revealing macrophage-derived VEGF-A as a crucial determinant of tissue responsiveness. Similarly, increased cardiac M2-like macrophage infiltration was found following F+H therapy post-MI, with strong correlation between macrophage levels and angiogenic and arteriogenic responses. In conclusion, M2-like macrophages play a decisive role, linked to VEGF-A production, in regulation of tissue responsiveness to angiogenic therapies including the combination of F+H. Our data suggest that future attempts at therapeutic revascularization in ischemic patients might benefit from coupling targeted growth factor delivery with either direct or indirect approaches to recruit pro-angiogenic macrophages in order to maximize therapeutic angiogenic/arteriogenic responses