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Loss-of-function studies have determined that Notch signaling is essential for hematopoietic and endothelial development. By deleting a single allele of the Notch1 transcriptional activation domain we generated viable, post-natal mice exhibiting hypomorphic Notch signaling. These heterozygous mice, which lack only one copy of the transcriptional activation domain, appear normal and have no endothelial or hematopoietic phenotype, apart from an inherent, cell-autonomous defect in T-cell lineage development. Following chemotherapy, these hypomorphs exhibited severe pancytopenia, weight loss and morbidity. This phenotype was confirmed in an endothelial-specific, loss-of-function Notch1 model system. Ang1, secreted by hematopoietic progenitors after damage, activated endothelial Tie2 signaling, which in turn enhanced expression of Notch ligands and potentiated Notch1 receptor activation. In our heterozygous, hypomorphic model system, the mutant protein that lacks the Notch1 transcriptional activation domain accumulated in endothelial cells and interfered with optimal activity of the wildtype Notch1 transcriptional complex. Failure of the hypomorphic mutant to efficiently drive transcription of key gene targets such as Hes1 and Myc prolonged apoptosis and limited regeneration of the bone marrow niche. Thus, basal Notch1 signaling is sufficient for niche development, but robust Notch activity is required for regeneration of the bone marrow endothelial niche and hematopoietic recovery.

Gliogenesis in the adult mouse brain Neural stem cells in the adult mouse brain can generate both neurons and glia. Exactly where each stem cell is positioned can determine what type of neurons it generates. Delgado et al. show that neural stem cells are also choosy about what sorts of glia they make and when (see the Perspective by Baldwin and Silver). Injury or selective deletion of platelet-derived growth factor receptor β (PDGFRβ) from the stem cells kicked them into overdrive and revealed their selectivity with respect to gliogenesis. An unusual type of glial progenitor cell, intraventricular oligodendrocyte progenitors, are found nestled between the cilia of ependymal cells derived from tight clusters of PDGFRβ-expressing stem cells. Science , abg8467, this issue p. 1205 ; see also abj1139, p. 1151

Arteriovenous malformations (AVMs) are high-flow lesions directly connecting arteries and veins. In the brain, AVM rupture can cause seizures, stroke, and death. Patients with AVMs exhibit reduced coverage of the vessels by pericytes, the mural cells of microvascular capillaries; however, the mechanism underlying this pericyte reduction and its association with AVM pathogenesis remains unknown. Notch signaling has been proposed to regulate critical pericyte functions. We hypothesized that Notch signaling in pericytes is crucial to maintain pericyte homeostasis and prevent AVM formation. We inhibited Notch signaling specifically in perivascular cells and analyzed the vasculature of these mice. The retinal vessels of mice with deficient perivascular Notch signaling developed severe AVMs, together with a significant reduction in pericytes and vascular smooth muscle cells (vSMC) in the arteries, while vSMCs were increased in the veins. Vascular malformations and pericyte loss were also observed in the forebrain of embryonic mice deficient for perivascular Notch signaling. Moreover, the loss of Notch signaling in pericytes downregulated Pdgfrb levels and increased pericyte apoptosis, pointing to a critical role for Notch in pericyte survival. Overall, our findings reveal a mechanism of AVM formation and highlight the Notch signaling pathway as an essential mediator in this process., Notch signaling promotes pericyte survival, and conditional loss of Notch in murine perivascular cells leads to arteriovenous malformations.

Pericytes are essential mural cells distinguished by their association with small caliber blood vessels and the presence of a basement membrane shared with endothelial cells. Pericyte interaction with the endothelium plays an important role in angiogenesis; however, very few tools are currently available that allow for the targeting of pericytes in mouse models, limiting our ability to understand their biology. We have generated a novel mouse line expressing tamoxifen-inducible Cre-recombinase under the control of the platelet-derived growth factor receptor β promoter: PDGFRβ-P2A-CreER T2 . We evaluated the expression of the PDGFRβ-P2A-CreER T2 line by crossing it with fluorescent reporter lines and analyzed reporter signal in the angiogenic retina and brain at different time points after tamoxifen administration. Reporter lines showed labeling of NG2+, desmin+, PDGFRβ+ perivascular cells in the retina and the brain, indicating successful targeting of pericytes; however, signal from reporter lines was also observed in a small subset of glial cells both in the retina and the brain. We also evaluated recombination in tumors and found efficient recombination in perivascular cells associated with tumor vasculature. As a proof of principle, we used our newly generated driver to delete Notch signaling in perivascular cells and observed a loss of smooth muscle cells in retinal arteries, consistent with previously published studies evaluating Notch3 null mice. We conclude that the PDGFRβ-P2A-CreER T2 line is a powerful new tool to target pericytes and will aid the field in gaining a deeper understanding of the role of these cells in physiological and pathological settings.

Quiescent neural stem cells (NSCs) in the adult ventricular-subventricular zone (V-SVZ) have a regional identity and undergo activation to generate neurons. The domains for gliogenesis are less explored. Here we show that Platelet-Derived Growth Factor Receptor beta (PDGFRβ) is expressed by adult V-SVZ NSCs that generate olfactory bulb interneurons and glia with slow baseline kinetics. Selective deletion of PDGFRβ in adult V-SVZ NSCs leads to their release from quiescence uncovering multiple domains in the septal wall for oligodendrocyte and astrocyte formation. Unexpectedly, we identify a novel intraventricular oligodendrocyte progenitor inside the brain ventricles. Together our findings reveal different NSC spatial domains for gliogenesis in the adult V-SVZ that are largely quiescent under homeostasis and may have key functions for brain plasticity.

Chagas disease is caused by the protozoan Trypanosoma cruzi, affecting millions of people worldwide. One of the major causes of mortality in the disease is the cardiomyopathy observed in chronic patients, despite the low number of parasites detected in cardiac tissue. Galectin-3, a carbohydrate-binding protein with affinity for β-galactoside-containing glycoconjugates, is upregulated upon infection, and it has been recently involved in the pathophysiology of heart failure.We investigated the role of galectin-3 in systemic and local responses in a murine model of T. cruzi infection, using knockout animals. Molecular mechanisms underlying galectin-3-dependent inflammatory responses were further assessed in cultured dendritic cells in vitro.Mice deficient for galectin-3 have elevated blood parasitemia levels and impaired cytokine production during infection. Remarkably, galectin-3 promotes cellular infiltration in the heart of infected mice and subsequent collagen deposition and cardiac fibrosis. Furthermore, we show that an unbalanced Toll-like receptor expression on antigen-presenting cells may be the cause of the impaired immune response observed in galectin-3-deficient mice in vivo.These results suggest that galectin-3 is strongly involved in Chagas disease, not only in the immune response against T. cruzi, but also in mediating cardiac tissue damage.

A proangiogenic role for Jagged (JAG)-dependent activation of NOTCH signaling in the endothelium has yet to be described. Using proteins that encoded different NOTCH1 EGF-like repeats, we identified unique regions of Delta-like ligand (DLL)–class and JAG-class ligand–receptor interactions, and developed NOTCH decoys that function as ligand-specific NOTCH inhibitors. N110–24 decoy blocked JAG1/JAG2–mediated NOTCH1 signaling, angiogenic sprouting in vitro, and retinal angiogenesis, demonstrating that JAG-dependent NOTCH signal activation promotes angiogenesis. In tumors, N110–24 decoy reduced angiogenic sprouting, vessel perfusion, pericyte coverage, and tumor growth. JAG–NOTCH signaling uniquely inhibited expression of antiangiogenic soluble (s) VEGFR1/sFLT1. N11–13 decoy interfered with DLL1–DLL4-mediated NOTCH1 signaling and caused endothelial hypersprouting in vitro, in retinal angiogenesis, and in tumors. Thus, blockade of JAG- or DLL-mediated NOTCH signaling inhibits angiogenesis by distinct mechanisms. JAG–NOTCH signaling positively regulates angiogenesis by suppressing sVEGFR1–sFLT1 and promoting mural–endothelial cell interactions. Blockade of JAG-class ligands represents a novel, viable therapeutic approach to block tumor angiogenesis and growth. Significance: This is the first report identifying unique regions of the NOTCH1 extracellular domain that interact with JAG-class and DLL-class ligands. Using this knowledge, we developed therapeutic agents that block JAG-dependent NOTCH signaling and demonstrate for the first time that JAG blockade inhibits experimental tumor growth by targeting tumor angiogenesis. Cancer Discov; 5(2); 182–97. ©2014 AACR. See related commentary by Briot and Iruela-Arispe, p. 112 This article is highlighted in the In This Issue feature, p. 97

Arteriovenous malformations (AVMs) are tortuous vessels characterized by arteriovenous (AV) shunts, which displace capillaries and shunt blood directly from artery to vein. Notch signaling regulates embryonic AV specification by promoting arterial, as opposed to venous, endothelial cell (EC) fate. To understand the essential role of endothelial Notch signaling in postnatal AV organization, we used inducible Cre-loxP recombination to delete Rbpj, a mediator of canonical Notch signaling, from postnatal ECs in mice. Deletion of endothelial Rbpj from birth resulted in features of AVMs by P14, including abnormal AV shunting and tortuous vessels in the brain, intestine and heart. We further analyzed brain AVMs, as they pose particular health risks. Consistent with AVM pathology, we found cerebral hemorrhage, hypoxia and necrosis, and neurological deficits. AV shunts originated from capillaries (and possibly venules), with the earliest detectable morphological abnormalities in AV connections by P8. Prior to AV shunt formation, alterations in EC gene expression were detected, including decreased Efnb2 and increased Pai1, which encodes a downstream effector of TGFβ signaling. After AV shunts had formed, whole-mount immunostaining showed decreased Efnb2 and increased Ephb4 expression within AV shunts, suggesting that ECs were reprogrammed from arterial to venous identity. Deletion of Rbpj from adult ECs led to tortuosities in gastrointestinal, uterine and skin vascular beds, but had mild effects in the brain. Our results demonstrate a temporal requirement for Rbpj in postnatal ECs to maintain proper artery, capillary and vein organization and to prevent abnormal AV shunting and AVM pathogenesis.

Liver vasculature is crucial for adequate hepatic functions. Global deletion of Notch signaling in mice results in liver vascular pathologies. However, whether Notch in endothelium is essential for hepatic vascular structure and function remains unknown. To uncover the function of endothelial Notch in the liver, we deleted Rbpj, a transcription factor mediating all canonical Notch signaling, or Notch1, specifically from the endothelium of postnatal mice. We investigated the hepatic vascular defects in these mutants. The liver was severely affected within two weeks following endothelial deletion of Rbpj from birth. Two-week old mutant mice had enlarged vessels on the liver surface, abnormal vascular architecture, and dilated sinusoids. Vascular casting and fluorosphere passage experiments indicated the presence of porto-systemic shunts. These mutant mice presented severely necrotic liver parenchyma and significantly larger hypoxic areas, likely resulting from vascular shunts. We also found elevated levels of VEGF receptor 3 together with reduced levels of ephrin-B2, suggesting a possible contribution of these factors to the generation of hepatic vascular abnormalities. Deletion of Rbpj from the adult endothelium also led to dilated sinusoids, vascular shunts, and necrosis albeit milder than that in mice with deletion from birth. Similar to deletion of Rbpj, loss of endothelial Notch1 from birth led to similar hepatic vascular malformations within two weeks. Conclusions: Endothelial Notch signaling is essential for the development and maintenance of proper hepatic vascular architecture and function. Our findings may help understand the molecular pathogenesis of hepatic vascular malformation and the safety of therapeutics inhibiting Notch. This article is protected by copyright. All rights reserved.

Introduction: Gliomas are highly infiltrative tumors rendering complete resection impossible. As such, prognosis remains dismal. Recent studies have identified both proneural and mesenchymal cell populations. Crucially, recurring gliomas bear a mesenchymal phenotype. Understanding mechanisms driving mesenchymal transformation is important in developing tailored, more efficient therapeutic approaches. Methods: Using targeted biopsies from a mouse glioma model and human glioma databases, we applied bioinformatics and identified Notch as an additional master regulator (MR) protein driving mesenchymal transformation. To better understand the role of Notch, we overexpressed active forms of Notch1 (N1IC) or Notch3 (N3IC) in primary cells, orthotopic xenotransplants, and transgenic mouse models. We performed mouse survival studies and examined Notch-induced phenotypic alterations in tumor cells and the microenvironment using molecular and immunohistochemical approaches. Finally, we performed high-throughput drug and radiation screening studies to assess responses to treatment. Results: In silico analyses on RNAseq of biopsies from spatially distinct tumor regions in a mouse glioma model identified Notch as a highly active pathway in the cores of tumors undergoing mesenchymal transformation. Importantly, MR analysis of TCGA samples and single cell transcriptomic data identified the Notch pathway as a driver of proneural to mesenchymal transformation. Immunophenotyping and RNAseq profiling of human GBMs identified Notch receptors on tumor cells and Notch ligands on astrocytes and microglia suggesting potential microenvironment-mediated plasticity since Notch proteins are not frequently mutated in GBM. Overexpression of N1IC or N3IC in proneural cells induced mesenchymal transformation with slow proliferation and a highly invasive phenotype. Orthotransplantation of N3IC-expressing cells in mice led to slower growing tumors, perivascular invasion, increased recruitment of reactive phagocytes and slightly prolonged survival. A novel transgenic mouse model in which N1IC was overexpressed also led to prolonged survival compared to a control population. Importantly, high-throughput screening studies showed that N1IC and N3IC rendered tumor cells significantly more resistant to standard and targeted therapies, including irradiation and etoposide. Conclusions: Our study identifies Notch signaling as an important, likely microenvironment-driven pathway driving proneural to mesenchymal transformation in glioma. While Notch was shown to slow tumor growth and prolong survival, cells were more invasive and less sensitive to treatment. These findings suggest that Notch plays a role in the mesenchymal transformation and therapeutic resistance seen in post-treatment recurrence. Targeting Notch may therefore be important in improving therapeutic responses against glioma. Citation Format: Matei A. Banu, Athanassios Dovas, Henar Cuervo, Brianna Pereira, Aayushi Mahajan, Hongxu Ding, Mukesh Bansal, Sergey Pampou, Charles Karan, Andrea Califano, Peter A. Sims, Jan Kitajewski, Jeffrey N. Bruce, Peter Canoll. Notch is a master regulator of mesenchymal transformation and therapeutic resistance in glioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5103.

In Chagas disease, which is caused by Trypanosoma cruzi, macrophages and cardiomyocytes are the main targets of infection. Classical activation of macrophages during infection is protective, whereas alternative activation of macrophages is involved in the survival of host cells and parasites. We studied the expression of inducible nitric oxide synthase (iNOS) and arginase as markers of classical and alternative activation, respectively, in heart tissue during in vivo infection of BALB/c and C57BL/6 mice. We found that expression of arginase I and II, as well as that of ornithine decarboxylase, was much higher in BALB/c mice than in C57BL/6 mice and that it was associated with the parasite burden in heart tissue. iNOS and arginase II were expressed by cardiomyocytes. Interestingly, heart-infiltrated CD68 + macrophages were the major cell type expressing arginase I. T helper (Th) 1 and Th2 cytokines were expressed in heart tissue in both infected mouse strains; however, at the peak of parasite infection, the balance between Th1 and Th2 predominantly favored Th1 in C57BL/6 mice and Th2 in BALB/c mice. The results of the present study suggest that Th2 cytokines induce arginase expression, which may influence host and parasite cell survival but which might also down-regulate the counterproductive effects triggered by iNOS in the heart during infection.

Chagas disease, caused by Trypanosoma cruzi, affects several million people in Central and South America. About 30% of chronic patients develop cardiomyopathy probably caused by parasite persistence and/or autoimmunity. While several cross-reactive antibodies generated during mammal T. cruzi infection have been described, very few cross-reactive T cells have been identified. We performed adoptive transfer experiments of T cells isolated from chronically infected mice. The results showed the generation of cardiac pathology in the absence of parasites. We also transferred cross-reactive SAPA-specific T cells and observed unspecific alterations in heart repolarization, cardiac inflammatory infiltration, and tissue damage.

Several questions about the role of the oxygen sensor prolyl-hydroxylase 2 (PHD2) in cancer have not been addressed. First, the role of PHD2 in metastasis has not been studied in a spontaneous tumor model. Here, we show that global PHD2 haplodeficiency reduced metastasis without affecting tumor growth. Second, it is unknown whether PHD2 regulates cancer by affecting cancer-associated fibroblasts (CAFs). We show that PHD2 haplodeficiency reduced metastasis via two mechanisms: (1) by decreasing CAF activation, matrix production, and contraction by CAFs, an effect that surprisingly relied on PHD2 deletion in cancer cells, but not in CAFs; and (2) by improving tumor vessel normalization. Third, the effect of concomitant PHD2 inhibition in malignant and stromal cells (mimicking PHD2 inhibitor treatment) is unknown. We show that global PHD2 haplodeficiency, induced not only before but also after tumor onset, impaired metastasis. These findings warrant investigation of PHD2's therapeutic potential. publisher: Elsevier articletitle: The Cancer Cell Oxygen Sensor PHD2 Promotes Metastasis via Activation of Cancer-Associated Fibroblasts journaltitle: Cell Reports articlelink: http://dx.doi.org/10.1016/j.celrep.2015.07.010 content_type: article copyright: Copyright © 2015 The Authors. Published by Elsevier Inc. ispartof: Cell Reports vol:12 issue:6 pages:992-1005 ispartof: location:United States status: published

Inflammation plays an important role in the pathophysiology of Chagas disease, caused by Trypanosoma cruzi. Prostanoids are regulators of homeostasis and inflammation and are produced mainly by myeloid cells, being cyclooxygenases, COX-1 and COX-2, the key enzymes in their biosynthesis from arachidonic acid (AA). Here, we have investigated the expression of enzymes involved in AA metabolism during T. cruzi infection. Our results show an increase in the expression of several of these enzymes in acute T. cruzi infected heart. Interestingly, COX-2 was expressed by CD68+ myeloid heart-infiltrating cells. In addition, infiltrating myeloid CD11b+Ly6G- cells purified from infected heart tissue express COX-2 and produce prostaglandin E2 (PGE2) ex vivo. T. cruzi infections in COX-2 or PGE2- dependent prostaglandin receptor EP-2 deficient mice indicate that both, COX-2 and EP-2 signaling contribute significantly to the heart leukocyte infiltration and to the release of chemokines and inflammatory cytokines in the heart of T. cruzi infected mice. In conclusion, COX-2 plays a detrimental role in acute Chagas disease myocarditis and points to COX-2 as a potential target for immune intervention., This work was supported by (NG) grants from “Fondo de Investigaciones Sanitarias” (PS09/00538 and PI12/00289); “Universidad Autónoma de Madrid” and “Comunidad de Madrid” (CC08-UAM/SAL-4440/08); by (MF) grants from “Ministerio de Ciencia e Innovación” (SAF2010-17833); “Red de Investigación de Centros de Enfermedades Tropicales” (RICET RD12/0018/0004); European Union (HEALTH-FE-2008-22303, ChagasEpiNet); AECID Cooperation with Argentine (A/025417/09 and A/031735/10), Comunidad de Madrid (S-2010/BMD- 2332) and “Fundación Ramón Areces”. NAG was recipient of a ISCIII Ph.D. fellowship financed by the Spanish “Ministerio de Sanidad”. CCM and HC were recipients of contracts from SAF2010-17833 and PI060388, respectively.

Trypanosoma cruzi, the causative agent of Chagas' disease, induces multiple responses in the heart, a critical organ of infection and pathology in the host. Among diverse factors, eicosanoids and the vasoactive peptide endothelin-1 (ET-1) have been implicated in the pathogenesis of chronic chagasic cardiomyopathy. In the present study, we found that T. cruzi infection in mice induces myocardial gene expression of cyclooxygenase-2 (Cox2) and thromboxane synthase (Tbxas1) as well as endothelin-1 (Edn1) and atrial natriuretic peptide (Nppa). T. cruzi infection and ET-1 cooperatively activated the Ca2+/calcineurin (Cn)/nuclear factor of activated T cells (NFAT) signaling pathway in atrial myocytes, leading to COX-2 protein expression and increased eicosanoid (prostaglandins E2 and F2α, thromboxane A2) release. Moreover, T. cruzi infection of ET-1-stimulated cardiomyocytes resulted in significantly enhanced production of atrial natriuretic peptide (ANP), a prognostic marker for impairment in cardiac function of chagasic patients. Our findings support an important role for the Ca2+/Cn/NFAT cascade in T. cruzi-mediated myocardial production of inflammatory mediators and may help define novel therapeutic targets. © 2013 Corral et al., Ministerio de Ciencia y Tecnología, Spain (SAF2007-61716; SAF2005-02220); Red Temática de Investigación en Enfermedades Cardiovasculares (RECAVA RD06/0014/1013); Red de Investigación de Centros de Enfermedades Tropicales (RICET RD06/0021/0016); European Union (HEALTH-FE-2008-22303, ChagasEpiNet); Universidad Autónoma de Madrid and Comunidad de Madrid (CC08-UAM/SAL-4440/08); Fundación Ramón Areces and Agencia Española de Cooperación Internacional para el Desarrollo (AECID, A/9418/07 and A/017500/08 to M.F. and R.S.C.); and Fondo de Investigaciones Sanitarias (PS09/00538 to N.G.). R.S.C. is a Member of Research Career from Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina

Chagas myocarditis, which is caused by infection with the intracellular parasite Trypanosoma cruzi, remains the major infectious heart disease worldwide. Innate recognition through toll-like receptors (TLRs) on immune cells has not only been revealed to be critical for defense against T. cruzi but has also been involved in triggering the pathology. Subsequent studies revealed that this parasite activates nucleotide-binding oligomerization domain- (NOD-)like receptors and several particular transcription factors in TLR-independent manner. In addition to professional immune cells, T. cruzi infects and resides in different parenchyma cells. The innate receptors in nonimmune target tissues could also have an impact on host response. Thus, the outcome of the myocarditis or the inflamed liver relies on an intricate network of inflammatory mediators and signals given by immune and nonimmune cells. In this paper, we discuss the evidence of innate immunity to the parasite developed by the host, with emphasis on the crosstalk between immune and nonimmune cell responses, Agencia Nacional de Promoción Científica y Tecnológica (ANPCYT-Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-Argentina); Secretaría de Ciencia y Tecnología(SECYT-UNC); and Agencia Española de Cooperación; Internacional para el Desarrollo (AECID)

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, affects several million people in Latin America. Myocarditis, observed in the acute and chronic phases of the disease, is characterized by a mononuclear cell inflammatory infiltrate. We previously identified a myeloid cell population in the inflammatory heart infiltrate of infected mice that expressed arginase I. In this study, we purified CD11b(+) myeloid cells from the heart and analyzed their phenotype and function. Those CD11b(+) cells were ∼70% Ly6G(-)Ly6C(+) and 25% Ly6G(+)Ly6C(+). Moreover, purified CD11b(+)Ly6G(-) cells, but not Ly6G(+) cells, showed a predominant monocytic phenotype, expressed arginase I and inducible NO synthase, and suppressed anti-CD3/anti-CD28 Ab-induced T cell proliferation in vitro by an NO-dependent mechanism, activity that best defines myeloid-derived suppressor cells (MDSCs). Contrarily, CD11b(+)Ly6G(+) cells, but not CD11b(+)Ly6G(-) cells, expressed S100A8 and S100A9, proteins known to promote recruitment and differentiation of MDSCs. Together, our results suggest that inducible NO synthase/arginase I-expressing CD11b(+)Ly6G(-) myeloid cells in the hearts of T. cruzi-infected mice are MDSCs. Finally, we found plasma l-arginine depletion in the acute phase of infection that was coincident in time with the appearance of MDSCs, suggesting that in vivo arginase I could be contributing to l-arginine depletion and systemic immunosuppression. Notably, l-arginine supplementation decreased heart tissue parasite load, suggesting that sustained arginase expression through the acute infection is detrimental for the host. This is, to our knowledge, the first time that MDSCs have been found in the heart in the context of myocarditis and also in infection by T. cruzi., This work was supported by Ministerio de Ciencia y Tecnología (SAF2007-61716 and SAF2005-02220); Fondo de Investigaciones Sanitarias (PS09/00538); Red Tematica de Investigación en Enfermedades Cardiovasculares (RECAVA RD06/0014/1013); Red de Investigación de Centros de Enfermedades Tropicales (RICET RD06/0021/0016); European Union (HEALTH-FE-2008-22303, ChagasEpiNet); Universidad Autónoma de Madrid and Comunidad de Madrid (CC08-UAM/SAL-4440/08); Agencia Española de Cooperación Internacional para el Desarrollo cooperation with Argentina (A/025417/09); and Fundación Ramón Areces. H.C. and N.A.G. were financed by Fondo de Investigaciones Sanitarias, Instituto de salud Carlos III contracts. S.C. was a holder of a Formación de personal investigador fellowship. A.B. was funded by the Interuniversity Attraction Pole Program of the Belgian government.

SummaryOur findings that PlGF is a cancer target and anti-PlGF is useful for anticancer treatment have been challenged by Bais et al. Here we take advantage of carcinogen-induced and transgenic tumor models as well as ocular neovascularization to report further evidence in support of our original findings of PlGF as a promising target for anticancer therapies. We present evidence for the efficacy of additional anti-PlGF antibodies and their ability to phenocopy genetic deficiency or silencing of PlGF in cancer and ocular disease but also show that not all anti-PlGF antibodies are effective. We also provide additional evidence for the specificity of our anti-PlGF antibody and experiments to suggest that anti-PlGF treatment will not be effective for all tumors and why. Further, we show that PlGF blockage inhibits vessel abnormalization rather than density in certain tumors while enhancing VEGF-targeted inhibition in ocular disease. Our findings warrant further testing of anti-PlGF therapies.

Chagas’ disease, caused by Trypanosoma cruzi, has been considered a paradigm of infection-induced autoimmune disease. Thus, the scarcity of parasites in the chronic phase of the disease contrasts with the severe cardiac pathology observed in approximately 30% of chronic patients and suggested a role for autoimmunity as the origin of the pathology. Antigen-specific and antigen-non-specific mechanisms have been described by which T. cruzi infection might activate T and B cells, leading to autoimmunity. Among the first mechanisms, molecular mimicry has been claimed as the most important mechanism leading to autoimmunity and pathology in the chronic phase of this disease. In this regard, various T. cruzi antigens, such as B13, cruzipain and Cha, cross-react with host antigens at the B or T cell level and their role in pathogenesis has been widely studied. Immunization with those antigens and/or passive transfer of autoreactive T lymphocytes in mice lead to clinical disturbances similar to those found in Chagas’ disease patients. On the other hand, the parasite is becoming increasingly detected in chronically infected hosts and may also be the cause of pathology either directly or through parasite-specific mediated inflammatory responses. Thus, the issue of autoimmunity versus parasite persistence as the cause of Chagas’ disease pathology is hotly debated among many researchers in the field. We critically review here the evidence in favor of and against autoimmunity through molecular mimicry as responsible for Chagas’ disease pathology from clinical, pathological and immunological perspectives.