[Show abstract][Hide abstract] ABSTRACT: Solid tumors are infiltrated by immune cells where macrophages and senescent T cells are highly represented. Within the tumor microenvironment, a cross-talk between the infiltrating cells may occur conditioning the characteristic of the in situ immune response. Our previous work showed that tumors induce senescence of T cells, which are powerful suppressors of lympho-proliferation. In this study, we report that Tumor-Induced Senescent (TIS)-T cells may also modulate monocyte activation. To gain insight into this interaction, CD4+ or CD8+TIS-T or control-T cells were co-incubated with autologous monocytes under inflammatory conditions. After co-culture with CD4+ or CD8+TIS-T cells, CD14+ monocytes/macrophages (Mo/Ma) exhibit a higher expression of CD16+ cells and a reduced expression of CD206. These Mo/Ma produce nitric oxide and reactive oxygen species; however, TIS-T cells do not modify phagocyte capacity of Mo/Ma. TIS-T modulated-Mo/Ma show a higher production of pro-inflammatory cytokines (TNF, IL-1β and IL-6) and angiogenic factors (MMP-9, VEGF-A and IL-8) and a lower IL-10 and IP-10 secretion than monocytes co-cultured with controls. The mediator(s) present in the supernatant of TIS-T cell/monocyte-macrophage co-cultures promote(s) tubulogenesis and tumor-cell survival. Monocyte-modulation induced by TIS-T cells requires cell-to-cell contact. Although CD4+ shows different behavior from CD8+TIS-T cells, blocking mAbs against T-cell immunoglobulin and mucin protein 3 and CD40 ligand reduce pro-inflammatory cytokines and angiogenic factors production, indicating that these molecules are involved in monocyte/macrophage modulation by TIS-T cells. Our results revealed a novel role for TIS-T cells in human monocyte/macrophage modulation, which may have deleterious consequences for tumor progression. This modulation should be considered to best tailor the immunotherapy against cancer.
Cell Death & Disease 01/2014; 5:e1507. · 6.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: B1 cells produce most natural Abs in unimmunized mice and play a key role in the response to thymus-independent Ags and microbial infection. Enlargement of B1 cell number in mice is often associated with autoimmunity. However, the factors that control peripheral B1 cell survival remain poorly characterized. Mice lacking the inhibitory receptor FcγRIIb exhibit a massive expansion in peritoneal B1 cells, implicating this receptor in B1 cell homeostasis. In this study, we show that peritoneal B1 cells express the highest levels of FcγRIIb among B cell subsets and are highly susceptible to FcγRIIb-mediated apoptosis. B1 cells upregulate FcγRIIb in response to innate signals, including CpG, and the B cell homeostatic cytokine BAFF efficiently protects activated B1 cells from FcγRIIb-mediated apoptosis via receptor downregulation. BAFF-transgenic mice manifest an expansion of peritoneal B1 cells that express lower levels of FcγRIIb and exhibit reduced susceptibility to apoptosis. Whereas both peritoneal B1 cells from wild-type and BAFF-transgenic mice immunized with CpG exhibit an increase in FcγRIIb levels, this change is blunted in BAFF-transgenic animals. Our combined results demonstrate that FcγRIIb controls peritoneal B1 cell survival and this program can be modulated by the BAFF signaling axis.
The Journal of Immunology 04/2012; 188(10):4792-800. · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Members of the IL-17 cytokine family play an important role in protection against pathogens through the induction of different effector mechanisms. We determined that IL-17A, IL-17E and IL-17F are produced during the acute phase of T. cruzi infection. Using IL-17RA knockout (KO) mice, we demonstrate that IL-17RA, the common receptor subunit for many IL-17 family members, is required for host resistance during T. cruzi infection. Furthermore, infected IL-17RA KO mice that lack of response to several IL-17 cytokines showed amplified inflammatory responses with exuberant IFN-γ and TNF production that promoted hepatic damage and mortality. Absence of IL-17RA during T. cruzi infection resulted in reduced CXCL1 and CXCL2 expression in spleen and liver and limited neutrophil recruitment. T. cruzi-stimulated neutrophils secreted IL-10 and showed an IL-10-dependent suppressive phenotype in vitro inhibiting T-cell proliferation and IFN-γ production. Specific depletion of Ly-6G+ neutrophils in vivo during T. cruzi infection raised parasitemia and serum IFN-γ concentration and resulted in increased liver pathology in WT mice and overwhelming wasting disease in IL-17RA KO mice. Adoptively transferred neutrophils were unable to migrate to tissues and to restore resistant phenotype in infected IL-17RA KO mice but migrated to spleen and liver of infected WT mice and downregulated IFN-γ production and increased survival in an IL-10 dependent manner. Our results underscore the role of IL-17RA in the modulation of IFN-γ-mediated inflammatory responses during infections and uncover a previously unrecognized regulatory mechanism that involves the IL-17RA-mediated recruitment of suppressive IL-10-producing neutrophils.
[Show abstract][Hide abstract] ABSTRACT: In this review, we discuss how protozoan parasites alter immature and mature B cell compartment. B1 and marginal zone (MZ) B cells, considered innate like B cells, are activated during protozoan parasite infections, and they generate short lived plasma cells providing a prompt antibody source. In addition, protozoan infections induce massive B cell response with polyclonal activation that leads to hypergammaglobulnemia with serum antibodies specific for the parasites and self and/or non related antigens. To protect themselves, the parasites have evolved unique ways to evade B cell immune responses inducing apoptosis of MZ and conventional mature B cells. As a consequence of the parasite induced-apoptosis, the early IgM response and an already establish humoral immunity are affected during the protozoan parasite infection. Moreover, some trypanosomatides trigger bone marrow immature B cell apoptosis, influencing the generation of new mature B cells. Simultaneously with their ability to release antibodies, B cells produce cytokines/quemokines that influence the characteristic of cellular immune response and consequently the progression of parasite infections.
Journal of Parasitology Research 01/2012; 2012:362131.
[Show abstract][Hide abstract] ABSTRACT: We have previously reported that many types of tumors can induce changes in human T cells that lead to the acquisition of suppressive function and phenotypic alterations resembling those found in senescent T cells. In the present study, we find a role for interleukin 7 (IL-7) in protecting T cells from these changes and further define involved signaling pathways.
We evaluated the ability of IL-7 treatment to prevent the gain of suppressive function and phenotypic alterations in human T cells after a short coculture with tumor cells in vitro. We then used inhibitors of components of the phosphoinositide 3-kinase (PI3K)/AKT pathway and short interfering RNA knockdown of Mcl-1 and Bim to evaluate the role of these signaling pathways in IL-7 protection.
We found that IL-7 inhibits CD27/CD28 loss and maintains proliferative capacity, IL-2 production, and reduced suppressive function. The protective ability of IL-7 depended on activation of the PI3K/AKT pathway, which inhibited activation of glycogen synthase kinase 3β, which, in turn, prevented the phosphorylation and loss of Mcl-1. We further showed a key role for Mcl-1 in that its knockdown or inhibition abrogated the effects of IL-7. In addition, knockdown of the Mcl-1 binding partner and proapoptotic protein Bim protected T cells from these dysfunctional alterations.
These observations confirm the role for Bcl-2 family members in cytokine signaling and suggest that IL-7 treatment in combination with other immunotherapies could lead to new clinical strategies to maintain normal T-cell function and reduce tumor-induced generation of dysfunctional and suppressor T cells.
Clinical Cancer Research 06/2011; 17(15):4975-86. · 7.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Acute infection with Trypanosoma cruzi, the aetiological agent of Chagas' disease, results in parasitaemia and polyclonal lymphocyte activation. It has been reported that polyclonal B-cell activation is associated with hypergammaglobulinaemia and delayed parasite-specific antibody response. In the present study we analysed the development of a B-cell response within the different microenvironments of the spleen during acute T. cruzi infection. We observed massive germinal centre (GC) and extrafollicular (EF) responses at the peak of infection. However, the EF foci were evident since day 3 post-infection (p.i.), and, early in the infection, they mainly provided IgM. The EF foci response reached its peak at 11 days p.i. and extended from the red pulp into the periarteriolar lymphatic sheath. The GCs were detected from day 8 p.i. At the peak of parasitaemia, CD138(+) B220(+) plasma cells in EF foci, red pulp and T-cell zone expressed IgM and all the IgG isotypes. Instead of the substantial B-cell response, most of the antibodies produced by splenic cells did not target the parasite, and parasite-specific IgG isotypes could be detected in sera only after 18 days p.i. We also observed that the bone marrow of infected mice presented a strong reduction in CD138(+) B220(+) cells compared with that of normal mice. Hence, in acute infection with T. cruzi, the spleen appears to be the most important lymphoid organ that lodges plasma cells and the main producer of antibodies. The development of a B-cell response during T. cruzi infection shows features that are particular to T. cruzi and other protozoan infection but different to other infections or immunization with model antigens.
[Show abstract][Hide abstract] ABSTRACT: Humoral immunity during experimental Chagas disease has been considered a double-edge sword, critical to control Trypanosoma cruzi spreading but also associated to tissue damage. Peritoneal B-1 cells have been linked to the pathogenesis of Chagas disease; however, they may also help to control the infection by providing a fast wave of antibodies. In the present work, we determined that peritoneal B-cell response to T. cruzi is characterized by a marked reduction of CD19(+) B cells due to plasma cell differentiation rather than to cell death. Both peritoneal B-2 and B-1 cells decrease after parasite infection, but with different kinetics. Thus, the reduction in B-2 cell number can be detected from day 4 postinfection while the number of B-1 cells decreases only after 15 days of infection. Differentiation of peritoneal B-1 and B-2 cells into IgM-secreting cells was triggered by parasites but not by cytokines produced by peritoneal cells. Electron microscopy studies showed that peritoneum of infected mice lodges plasma cells with typical morphology as well as atypical plasma cells named 'Mott-like cells' containing high number of cytoplasmatic Ig(+) granules. The plasma cells induced during the infection showed a phenotype that may allow their persistence in peritoneum and they may contribute to the high levels of antibodies exhibited at the chronic phase of infection. We also showed that the peritoneal B-cell response is scarcely specific for the invading pathogen and rather constitute an important source of non-parasite-specific IgM and IgG in the infected host.
International Immunology 03/2010; 22(5):399-410. · 3.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: B cells and antibodies are involved not only in controlling the spread of blood circulating Trypanosoma cruzi, but also in the autoreactive manifestations observed in Chagas disease. Acute infection results in polyclonal B cell activation associated with hypergammaglobulinemia, delayed specific humoral immunity and high levels of non-parasite specific antibodies. Since TNF superfamily B lymphocyte Stimulator (BAFF) mediates polyclonal B cell response in vitro triggered by T. cruzi antigens, and BAFF-Tg mice show similar signs to T. cruzi infected mice, we hypothesized that BAFF can mediate polyclonal B cell response in experimental Chagas disease.
BAFF is produced early and persists throughout the infection. To analyze BAFF role in experimental Chagas disease, Balb/c infected mice were injected with BR3:Fc, a soluble receptor of BAFF, to block BAFF activity. By BAFF blockade we observed that this cytokine mediates the mature B cell response and the production of non-parasite specific IgM and IgG. BAFF also influences the development of antinuclear IgG and parasite-specific IgM response, not affecting T. cruzi-specific IgG and parasitemia. Interestingly, BAFF inhibition favors the parasitism in heart.
Our results demonstrate, for the first time, an active role for BAFF in shaping the mature B cell repertoire in a parasite infection.
[Show abstract][Hide abstract] ABSTRACT: CD137 (4-1BB)-mediated costimulation plays an important role in directing the fate of Ag-stimulated T cells and NK cells, yet the role of CD137 in mediating B cell function is unknown. We found that CD137 is expressed in vitro on anti-Ig-stimulated peripheral blood B cells and in vivo on tonsillar B cells with an activated phenotype. In vitro CD137 expression is enhanced by CD40 stimulation and IFN-gamma and is inhibited by IL-4, -10, and -21. The expression of CD137 on activated human B cells is functionally relevant because engagement with its ligand at the time of activation stimulates B cell proliferation, enhances B cell survival, and induces secretion of TNF-alpha and -beta. Our study suggests that CD137 costimulation may play a role in defining the fate of Ag-stimulated human B cells.
The Journal of Immunology 12/2009; 184(2):787-95. · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Senescent and suppressor T cells are reported to be increased in select patients with cancer and are poor prognostic indicators. Based on the association of these T cells and poor outcomes, we hypothesized that tumors induce senescence in T cells, which negatively effects antitumor immunity. In this report, we show that human T cells from healthy donors incubated with tumor for only 6 h at a low tumor to T-cell ratio undergo a senescence-like phenotype, characterized by the loss of CD27 and CD28 expression and telomere shortening. Tumor-induced senescence of T cells is induced by soluble factors and triggers increases in expression of senescence-associated molecules such as p53, p21, and p16. Importantly, these T cells are not only phenotypically altered, but also functionally altered as they can suppress the proliferation of responder T cells. This suppression requires cell-to-cell contact and is mediated by senescent CD4(+) and CD8(+) subpopulations, which are distinct from classically described natural T regulatory cells. Our observations support the novel concept that tumor can induce senescent T cells with suppressor function and may effect both the diagnosis and treatment of cancer.
Cancer Research 03/2008; 68(3):870-9. · 9.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polyclonal B cell activation is not a peculiar characteristic to a particular infection, as many viruses, bacteria, and parasites induce a strong polyclonal B cell response resulting in hyper-gamma-globulinemia. Here, we discuss the different roles proposed for polyclonal B cell activation, which can be crucial for early host defense against rapidly dividing microorganisms by contributing antibodies specific for a spectrum of conserved structures present in the pathogens. In addition, polyclonal B cell activation can be responsible for maintenance of memory B cell responses because of the continuous, unrestricted stimulation of memory B cells whose antibody production may be sustained in the absence of the antigens binding-specific BCR. Conversely, polyclonal activation can be triggered by microorganisms to avoid the host-specific, immune response by activating B cell clones, which produce nonmicroorganism-specific antibodies. Finally, some reports suggest a deleterious role for polyclonal activation, arguing that it could potentially turn on anti-self-responses and lead to autoimmune manifestations during chronic infections.
Journal of Leukocyte Biology 12/2007; 82(5):1027-32. · 4.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microorganisms with pathogen-associated molecular patterns (PAMP) activate B cells directly by binding to TLR and also indirectly by inducing APC to release cytokines such as BAFF that promote B cell survival. We found that murine B cells activated concomitantly with LPS (TLR-4 ligand) and BAFF are protected from spontaneous apoptosis, but are more susceptible to Fas/CD95-mediated cell death. This increased susceptibility to Fas-induced apoptosis is associated with a dramatic coordinated up-regulation of Fas/CD95 and IRF-4 expression through a mechanism mediated, at least in part, by inhibition of the MEK/ERK pathway. Up-regulation of Fas/CD95 by BAFF is restricted to B cells activated through TLR-4, but not through TLR-9, BCR or CD40. TLR ligands differ in the BAFF family receptors (R) they induce on B cells: BAFF-R is increased by the TLR4 ligand, LPS, but not by the TLR9 ligand, CpG-containing oligodeoxynucleotides, which, in contrast, strongly up-regulates transmembrane activator and CAML interactor (TACI). This suggests the up-regulation of Fas by BAFF is mediated by BAFF-R and not by TACI. Consistently, APRIL, which binds to TACI and B cell maturation antigen but not BAFF-R, did not enhance Fas expression on LPS-activated B cells. Increased susceptibility to Fas-mediated killing of B cells activated with LPS and BAFF may be a fail-safe mechanism to avoid overexpansion of nonspecific or autoreactive B cells.
European Journal of Immunology 05/2007; 37(4):990-1000. · 4.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The whole life of a B-cell from a stem cell to a mature plasma cell is governed, among other factors, by cytokines and growth factors in their microenvironment. Remarkable progress in the understanding of the mechanisms of cytokines action on the B-cell compartment was achieved by analysis of gene-targeted mice. The generation of mice deficient for individual cytokines or their receptors has shed light on the in vivo function of cytokines in B-cell responses. This review focuses on the role of cytokines in the development, maturation and differentiation of different B-cell subsets into antibody-secreting cells or memory B-cells.
[Show abstract][Hide abstract] ABSTRACT: Trypanosoma cruzi, the causative agent of Chagas' disease, may sabotage humoral response by affecting B cells at the different stages of its development. The present review highlights the contributions of our laboratory in understanding how T. cruzi hinders B-cell generation and B-cell expansion limiting host defence and favouring its chronic establishment. We discuss how homoeostatic mechanisms can be triggered to control exacerbated B-cell proliferation that favour T. cruzi infection by eliminating parasite-specific B cells. Specific targeting of evasion mechanisms displayed in T. cruzi infection, as in vivo Fas/FasL blockade or Gal-3 expression inhibition, allowed us to modulate B-cell responses enhancing the anti-parasite humoral immune response. A comprehensive understanding of the biology of the B cell in health and disease is strictly required to devise immunointervention strategies aimed at enhancing protective immune responses during infections.
Scandinavian Journal of Immunology 01/2007; 66(2-3):137-42. · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Microbial-induced polyclonal activation of B cells is a common event in several forms of infections, and is believed to play a crucial role both for enhancing the production of specific antibodies and for maintenance of B cell memory. Therefore, a major challenge in biomedical research is the identification of pathogen-derived products capable of rapidly mounting B cell expansion and differentiation. Here we report that glutamate dehydrogenase (GDH) stimulates polyclonal proliferation and differentiation of naive B cells. This stimulation was found to be T cell independent, but to absolutely require CD11b(+) cells. Moreover, we demonstrate that stimulation of CD11b(+) cells by GDH leads to the production of IL-6, IL-10 and B cell-activating factor (BAFF), all of which combine to powerfully induce B cell expansion. Importantly, IL-6 and IL-10 further drive B cell terminal differentiation into plasma cells by up-regulating critical transcription factors and immunoglobulin secretion. Our data provide the first evidence that a protozoan antigen can induce BAFF production by accessory cells, which in concert with other cytokines trigger polyclonal B cell activation.
European Journal of Immunology 07/2006; 36(6):1474-85. · 4.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During ageing, autoimmune disorders and the higher susceptibility to infectious have been associated with alterations in the humoral immune response. We report that splenic B lymphocytes from aged mice exhibit lower level of apoptosis induced by B-cell antigen receptor (BCR) ligation in vitro. Respect to B cells from young mice the anti-mu stimulated aged B cells show similar Bcl-2 and Bcl-xL expression but differential kinetic of A1 degradation and a higher level of cFLIP and FAIM. Even though B cells from aged mice show minor Fas expression they exhibit the same susceptibility to anti-Fas induced apoptosis. Aged B cells also present upon BCR stimulation, a higher proliferative response and similar level of activation markers expression than B cells from young mice. These data agree with the observation that aged mice exhibit an increment of T2 and mature B cell subset which rapidly enters cell cycle upon BCR engagement. The diminished apoptosis after activation in aged mice could compromise homeostatic mechanism allowing the persistence of self and non-self antigen specific B cells.
[Show abstract][Hide abstract] ABSTRACT: The ability of a microorganism to elicit or evade B cell responses represents a determinant factor for the final outcome of an infection. Although pathogens may subvert humoral responses at different stages of B cell development, most studies addressing the impact of an infection on the B cell compartment have focused on mature B cells within peripheral lymphoid organs. Herein, we report that a protozoan infection, i.e. a Trypanosoma cruzi infection, induces a marked loss of immature B cells in the BM, which also compromises recently emigrated B cells in the periphery. The depletion of BM immature B cells is associated with an increased rate of apoptosis mediated by a parasite-indirect mechanism in a Fas/FasL-independent fashion. Finally, we demonstrated that myeloid cells play an important role in B cell depletion, since CD11b(+) BM cells from infected mice secrete a product of the cyclooxygenase pathway that eliminates immature B cells. These results highlight a previously unrecognized maneuver used by a protozoan parasite to disable B cell generation, limiting host defense and favoring its chronic establishment.
European Journal of Immunology 07/2005; 35(6):1849-58. · 4.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The role of transcription factors in B cell survival and differentiation has been delineated during the last years. However, little is known about the intermediate signals and the intracellular pathways that control these events. In this study, we provide evidence both in vitro and in vivo, showing that galectin-3 (Gal-3), a beta-galactoside-binding protein, is a critical mediator of B cell differentiation and survival. Although Gal-3 is not expressed in resting B cells from normal mice, its expression is markedly induced after activation with stimuli such as IL-4 and CD40 cross-linking. These signals promote survival and block the final differentiation of these cells, thus allowing the rising of a memory B cell phenotype. In addition, Gal-3 is expressed in B cells from Trypanosoma cruzi-infected mice, which received signals for activation and differentiation in vivo. By using an antisense strategy, we determined that Gal-3 is a critical signal mediating the effects of IL-4 on B cell fate. Blockade of intracellular Gal-3 in vitro abrogated IL-4-induced survival of activated B cells, favoring the differentiation toward a plasma cell pathway. Moreover, B cells with restrained endogenous Gal-3 expression failed to down-regulate the Blimp-1 transcription factor after IL-4 stimulation. Finally, inhibition of Gal-3 in vivo skewed the balance toward plasma cell differentiation, which resulted in increased Ig production and parasite clearance during T. cruzi infection. Thus, the present study provides evidence of a novel role for Gal-3 as an intracellular mediator of B cell survival and a checkpoint in IL-4-induced B cell commitment toward a memory phenotype.
The Journal of Immunology 02/2004; 172(1):493-502. · 5.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It has been proposed that pregnancy-specific factors could be responsible for shift the balance of cytokine profiles during maternal immune response from Th1-type reactivity into a "less-damaging" Th2-type reactivity. In the present work, we investigated the in vivo function of human pregnancy-specific glycoprotein (PSG)1a, the major variant of PSG polypeptides released into the circulation during pregnancy, on the modulation of the innate and adaptive immune response. For this, BALB/c mice were injected with a vaccinia virus-based vector harboring the human PSG1a cDNA (Vac-PSG1a) 4 days before immunization with ovalbumin (OVA) in complete Freund's adjuvant, and the early specific T cell response against OVA was evaluated 8 days post-immunization. We also studied the activation status of spleen and peritoneal monocytes/macrophages (Mo) populations from Vac-PSG1a-treated mice, and explored whether PSG1a-targeted Mo could affect the Th-type commitment by investigating their impact on the differentiation of naive T cells. Our data show that the treatment with Vac-PSG1a is able to induce a state of alternative activation on Mo. Furthermore, the generation of the immune response in the context of these alternatively activated antigen-presenting cells may shift T cell differentiation to Th2-type immunity which is more compatible with a successful pregnancy.
European Journal of Immunology 12/2003; 33(11):3007-16. · 4.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present work, we demonstrate that interleukin (IL)-4 is able to rescue B cells from Trypanosoma cruzi-infected mice, counteracting the strong apoptotic signals that these cells received in vivo. We have observed that IL-4 restrains the apoptosis of immunoglobulin (Ig)M(+) and IgG(+) B cells from infected and normal mice without inducing them to proliferate. In addition, IL-4 does not modify the quantity or quality of the antibodies secreted by B cells from infected mice, as it blocks their terminal differentiation to plasma cells and favors memory pathway. It is interesting that the protective effect of IL-4 over B cells from infected mice is mediated, at least partly, by the down-regulation of Fas ligand (FasL) expression, which leads to interference in the apoptosis executed by these B cells through the Fas/FasL death pathway. Accordingly, a marked up-regulation of the "FasL gene repressor" class II transactivator was observed, suggesting that this would be one mechanism underlying the IL-4-mediated FasL down-regulation.
Journal of Leukocyte Biology 02/2003; 73(1):127-36. · 4.57 Impact Factor