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1.  Inhibins Tune the Thymocyte Selection Process by Regulating Thymic Stromal Cell Differentiation 
Journal of Immunology Research  2015;2015:837859.
Inhibins and Activins are members of the TGF-β superfamily that regulate the differentiation of several cell types. These ligands were initially identified as hormones that regulate the hypothalamus-pituitary-gonadal axis; however, increasing evidence has demonstrated that they are key regulators in the immune system. We have previously demonstrated that Inhibins are the main Activin ligands expressed in the murine thymus and that they regulate thymocyte differentiation, promoting the DN3-DN4 transition and the selection of SP thymocytes. As Inhibins are mainly produced by thymic stromal cells, which also express Activin receptors and Smad proteins, we hypothesized that Inhibins might play a role in stromal cell differentiation and function. Here, we demonstrate that, in the absence of Inhibins, thymic conventional dendritic cells display reduced levels of MHC Class II (MHCII) and CD86. In addition, the ratio between cTECs and mTECs was affected, indicating that mTEC differentiation was favoured and cTEC diminished in the absence of Inhibins. These changes appeared to impact thymocyte selection leading to a decreased selection of CD4SP thymocytes and increased generation of natural regulatory T cells. These findings demonstrate that Inhibins tune the T cell selection process by regulating both thymocyte and stromal cell differentiation.
PMCID: PMC4418002  PMID: 25973437
2.  Jak3 Enables Chemokine-Dependent Actin Cytoskeleton Reorganization by Regulating Cofilin and Rac/Rhoa GTPases Activation 
PLoS ONE  2014;9(2):e88014.
We have previously shown that Jak3 is involved in the signaling pathways of CCR7, CCR9 and CXCR4 in murine T lymphocytes and that Jak3−/− lymphocytes display an intrinsic defect in homing to peripheral lymph nodes. However, the molecular mechanism underlying the defective migration observed in Jak3−/− lymphocytes remains elusive. Here, it is demonstrated for the first time, that Jak3 is required for the actin cytoskeleton reorganization in T lymphocytes responding to chemokines. It was found that Jak3 regulates actin polymerization by controlling cofilin inactivation in response to CCL21 and CXCL12. Interestingly, cofilin inactivation was not precluded in PTX- treated cells despite their impaired actin polymerization. Additionally, Jak3 was required for small GTPases Rac1 and RhoA activation, which are indispensable for acquisition of the migratory cell phenotype and the generation of a functional leading edge and uropod, respectively. This defect correlates with data obtained by time-lapse video-microscopy showing an incompetent uropod formation and impaired motility in Jak3-pharmacologically inhibited T lymphocytes. Our data support a new model in which Jak3 and heterotrimeric G proteins can use independent, but complementary, signaling pathways to regulate actin cytoskeleton dynamics during cell migration in response to chemokines.
PMCID: PMC3912156  PMID: 24498424
3.  Transgenic Expression of Soluble Human CD5 Enhances Experimentally-Induced Autoimmune and Anti-Tumoral Immune Responses 
PLoS ONE  2014;9(1):e84895.
CD5 is a lymphoid-specific transmembrane glycoprotein constitutively expressed on thymocytes and mature T and B1a lymphocytes. Current data support the view that CD5 is a negative regulator of antigen-specific receptor-mediated signaling in these cells, and that this would likely be achieved through interaction with CD5 ligand/s (CD5L) of still undefined nature expressed on immune or accessory cells. To determine the functional consequence of loss of CD5/CD5L interaction in vivo, a new transgenic mouse line was generated (shCD5EμTg), expressing a circulating soluble form of human CD5 (shCD5) as a decoy to impair membrane-bound CD5 function. These shCD5EμTg mice showed an enhanced response to autologous antigens, as deduced from the presentation of more severe forms of experimentally inducible autoimmune disease (collagen-induced arthritis, CIA; and experimental autoimmune encephalitis, EAE), as well as an increased anti-tumoral response in non-orthotopic cancer models (B16 melanoma). This enhancement of the immune response was in agreement with the finding of significantly reduced proportions of spleen and lymph node Treg cells (CD4+CD25+FoxP3+), and of peritoneal IL-10-producing and CD5+ B cells, as well as an increased proportion of spleen NKT cells in shCD5EμTg mice. Similar changes in lymphocyte subpopulations were observed in wild-type mice following repeated administration of exogenous recombinant shCD5 protein. These data reveal the relevant role played by CD5/CD5L interactions on the homeostasis of some functionally relevant lymphocyte subpopulations and the modulation of immune responses to autologous antigens.
PMCID: PMC3893160  PMID: 24454761
4.  CD5-dependent CK2 activation pathway regulates threshold for T-cell anergy1 
CD5 activates CK2, a serine/threonine kinase that constitutively associates with the CK2-binding domain at the end of its cytoplasmic tail. To determine the physiological significance of CD5-dependent CK2 activation in T-cells we generated a knock-in mouse that expresses a CD5 protein containing a microdeletion with selective inability to interact with CK2 (CD5ΔCK2BD). The levels of CD5 on developing and mature T-cell populations from CD5ΔCK2BD mice and CD5WT mice were similar. The thymus of CD5ΔCK2BD mice contained fewer double positive (DP) thymocytes than that of both CD5WT and CD5KO mice, though the numbers of all other immature and mature T-cell populations were unaltered. CD5ΔCK2BD T-cells hypoproliferated and exhibited enhanced AICD when stimulated with anti-CD3 or cognate peptide in comparison to CD5WT T-cells. We also found that functional CD5-dependent CK2 signaling was necessary for efficient differentiation of naïve CD4+ T-cells into Th2 and Th17 cells, but not Th1 cells. We previously showed that experimental autoimmune encephalomyelitis (EAE) in CD5KO mice was less severe and delayed in onset than in CD5WT mice. Remarkably, CD5ΔCK2BD mice recapitulated both EAE severity and disease onset of CD5KO mice. Increasing the immunization dose of myelin oligodendrocyte (MOG35-55) peptide, a model that mimics high dose tolerance, led to decreased severity of EAE in CD5 WT mice but not in CD5KO or CD5ΔCK2BD mice. This property was recapitulated in in vitro re-stimulation assays. These results demonstrate that CD5-CK2 signaling sets the threshold for T-cell responsiveness and it is necessary for efficient generation of Th2 and Th17 cells.
PMCID: PMC3436980  PMID: 22904299
5.  Human CD4+ effector T lymphocytes generated upon TCR engagement with self-peptides respond defectively to IL-7 in their transition to memory cells 
Cellular and Molecular Immunology  2013;10(3):261-274.
The peripheral repertoire of CD4+ T lymphocytes contains autoreactive cells that remain tolerant through several mechanisms. However, nonspecific CD4+ T cells can be activated in physiological conditions as in the course of an ongoing immune response, and their outcome is not yet fully understood. Here, we investigate the fate of human naive CD4+ lymphocytes activated by dendritic cells (DCs) presenting endogenous self-peptides in comparison with lymphocytes involved in alloresponses. We generated memory cells (Tmem) from primary effectors activated with mature autologous DCs plus interleukin (IL)-2 (Tmauto), simulating the circumstances of an active immune response, or allogeneic DCs (Tmallo). Tmem were generated from effector cells that were rested in the absence of antigenic stimuli, with or without IL-7. Tmem were less activated than effectors (demonstrated by CD25 downregulation) particularly with IL-7, suggesting that this cytokine may favour the transition to quiescence. Tmauto and Tmallo showed an effector memory phenotype, and responded similarly to polyclonal and antigen-specific stimuli. Biochemically, IL-7-treated Tmallo were closely related to conventional memory lymphocytes based on Erk-1/2 activation, whereas Tmauto were more similar to effectors. Autologous effectors exhibited lower responses to IL-7 than allogeneic cells, which were reflected in their reduced proliferation and higher cell death. This was not related to IL-7 receptor expression but rather to signalling deficiencies, according to STAT5 activation These results suggest that ineffective responses to IL-7 could impair the transition to memory cells of naive CD4+ T lymphocytes recognizing self-peptides in the setting of strong costimulation.
PMCID: PMC4012772  PMID: 23454917
human CD4+ T cells; IL-7; memory; self-peptides
6.  Betaglycan (TβRIII) Is Expressed in the Thymus and Regulates T Cell Development by Protecting Thymocytes from Apoptosis 
PLoS ONE  2012;7(8):e44217.
TGF-β type III receptor (TβRIII) is a coreceptor for TGFβ family members required for high-affinity binding of these ligands to their receptors, potentiating their cellular functions. TGF-β [1]–[3], bone morphogenetic proteins (BMP2/4) and inhibins regulate different checkpoints during T cell differentiation. Although TβRIII is expressed on hematopoietic cells, the role of this receptor in the immune system remains elusive. Here, we provide the first evidence that TβRIII is developmentally expressed during T cell ontogeny, and plays a crucial role in thymocyte differentiation. Blocking of endogenous TβRIII in fetal thymic organ cultures led to a delay in DN-DP transition. In addition, in vitro development of TβRIII−/− thymic lobes also showed a significant reduction in absolute thymocyte numbers, which correlated with increased thymocyte apoptosis, resembling the phenotype reported in Inhibin α −/− thymic lobes. These data suggest that Inhibins and TβRIII may function as a molecular pair regulating T cell development.
PMCID: PMC3430661  PMID: 22952931
7.  The immunomodulatory properties of the CD5 lymphocyte receptor in health and disease 
Current opinion in immunology  2011;23(3):310-318.
CD5 is a scavenger-like receptor expressed in association with the antigen-specific receptors on T and B-1a lymphocytes. Recent studies reveal a broader biology for CD5 that includes its role as regulator of cell death and as a receptor for pathogen associated molecular patterns, in addition to its previously described function as an inhibitory receptor. These findings shed new light into the mechanistic role of CD5 in leukemias and effector cells to exogenous (infectious) or endogenous (autoimmune, tumoral) antigens. The newly identified properties make this receptor a potential candidate to be targeted for therapeutic intervention as well as immune modulation. This review describes the current knowledge on the function of CD5 as an immunomodulatory receptor both in health and disease.
PMCID: PMC3109098  PMID: 21482089
8.  High glucose concentrations induce TNF-α production through the down-regulation of CD33 in primary human monocytes 
BMC Immunology  2012;13:19.
CD33 is a membrane receptor containing a lectin domain and a cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM) that is able to inhibit cytokine production. CD33 is expressed by monocytes, and reduced expression of CD33 correlates with augmented production of inflammatory cytokines, such as IL-1β, TNF-α, and IL-8. However, the role of CD33 in the inflammation associated with hyperglycemia and diabetes is unknown. Therefore, we studied CD33 expression and inflammatory cytokine secretion in freshly isolated monocytes from patients with type 2 diabetes. To evaluate the effects of hyperglycemia, monocytes from healthy donors were cultured with different glucose concentrations (15-50 mmol/l D-glucose), and CD33 expression and inflammatory cytokine production were assessed. The expression of suppressor of cytokine signaling protein-3 (SOCS-3) and the generation of reactive oxygen species (ROS) were also evaluated to address the cellular mechanisms involved in the down-regulation of CD33.
CD33 expression was significantly decreased in monocytes from patients with type 2 diabetes, and higher levels of TNF-α, IL-8 and IL-12p70 were detected in the plasma of patients compared to healthy donors. Under high glucose conditions, CD33 protein and mRNA expression was significantly decreased, whereas spontaneous TNF-α secretion and SOCS-3 mRNA expression were increased in monocytes from healthy donors. Furthermore, the down-regulation of CD33 and increase in TNF-α production were prevented when monocytes were treated with the antioxidant α-tocopherol and cultured under high glucose conditions.
Our results suggest that hyperglycemia down-regulates CD33 expression and triggers the spontaneous secretion of TNF-α by peripheral monocytes. This phenomenon involves the generation of ROS and the up-regulation of SOCS-3. These observations support the importance of blood glucose control for maintaining innate immune function and suggest the participation of CD33 in the inflammatory profile associated with type 2 diabetes.
PMCID: PMC3353220  PMID: 22500980
Antioxidant; Cytokines; Monocytes; ROS; Siaglec-3; Type 2 diabetes
9.  122 Role of the CC− Chemokine Receptor CCR9 in the Regulation of Inflammatory Process During Allergic Airway Inflammation 
The World Allergy Organization Journal  2012;5(Suppl 2):S57-S58.
Airway eosinophilia and Th2 lymphocytes-recruitment to the lung are one of the main pathological features of asthma. It is clear now that the axis chemokine/chemokine receptors have a role in controlling leukocyte recruitment and development of the inflammatory process observed in asthma. Although it has been reported that CCR9 receptor is expressed in asthmatic patients, it is not known whether CCR9 may have a regulatory role of the development of this disease. Our aim was to analyze the expression of CCR9 in a murine model of allergic airway inflammation (WT) and compared to CCR9 deficient (KO) mice.
Four groups of 6 to 8 weeks female CCR9-deficient mice were sensitized by intraperitoneal injections of 10 micrograms of ovalbumin (OVA) in alum (ALOH3) diluted in PBS, on days 1 and 8 of the established sensitization protocol. Aerosolised OVA was administered (1% in PBS) on days 15, 20 and 34. 24 hours after last OVA exposure, mice were sacrificed and bronchoalveolar lavage (BAL) fluid and cells were obtained. Total and differential cell numbers were obtained and characterized cell subpopulations by FACS analysis. Cytokine/chemokine levels were quantified by ELISA and qRT-PCR respectively.
Total cell numbers in BAL were no significantly different between WT and KO mice. Interestingly, reduction in the numbers of eosinophils was observed in CCR9 KO mice compared to WT mice. Histological analysis of lung tissue demonstrated a reduction in the granulocytic population (eosinophils) in CCR9 KO mice. Analysis of cell subpopulations by FACS demonstrated that CD4+ lymphocytes were significantly reduced but CD8+ and CD19+ lymphocytes numbers were not different between WT and CCR9-deficient mice. A population of CCR9+ Gr1+ was altered in KO mice and it correlated with cytological analysis. Furthermore, histological analysis demonstrated alteration in mucus production in allergic airway in CCR9 deficient mice, accompanied with a no-significant reduction of OVA-specific anti-IgE antibodies in serum at the time of analysis.
Altogether, these results suggest that CCR9 may be involved in recruitment of granulocytic cell subpopulation into the allergic airways and have an impact in the regulation of the chronic inflammatory process.
PMCID: PMC3513118
10.  Activins and Inhibins: novel regulators of thymocyte development 
Activins and inhibins are members of the transforming growth factor β superfamily that act on different cell types and regulate a broad range of cellular processes including proliferation, differentiation, and apoptosis. Here, we provide the first evidence that activins and inhibins regulate specific checkpoints during thymocyte development. We demonstrate that both activin A and inhibin A promote the DN3-DN4 transition in vitro, although they differentially control the transition to the DP stage. Whereas activin A induces the accumulation of a CD8+CD24hiTCRβlo intermediate subpopulation, inhibin A promotes the differentiation of DN4 to DP. In addition, both activin A and inhibin A appear to promote CD8+SP differentiation Moreover, Inhibin α null mice have delayed in vitro T cell development, showing both a decrease in the DN-DP transition and reduced thymocyte numbers, further supporting a role for inhibins in the control of developmental signals taking place during T cell differentiation in vivo.
PMCID: PMC2693414  PMID: 19338778
Thymocytes; Cell Differentiation; Activins; Inhibins; Knockout Mice
11.  A New MAP Kinase Protein Involved in Estradiol-Stimulated Reproduction of the Helminth Parasite Taenia crassiceps 
MAP kinases (MAPK) are involved in the regulation of cellular processes such as reproduction and growth. In parasites, the role of MAPK has been scarcely studied. Here, we describe the participation of an ERK-like protein in estrogen-dependent reproduction of the helminth parasite Taenia crassiceps. Our results show that 17β-estradiol induces a concentration-dependent increase in the bud number of in vitro cultured cysticerci. If parasites are also incubated in presence of an ERK-inhibitor, the stimulatory effect of estrogen is blocked. The expression of ERK-like mRNA and its corresponding protein was detected in the parasite. The ERK-like protein was over-expressed by all treatments. Nevertheless, a strong induction of phosphorylation of this protein was observed only in response to 17β-estradiol. Cross-contamination by host cells was discarded by flow cytometry analysis. Parasite cells expressing the ERK-like protein were exclusively located at the subtegument tissue by confocal microscopy. Finally, the ERK-like protein was separated by bidimensional electrophoresis and then sequenced, showing the conserved TEY activation motif, typical of all known ERK 1/2 proteins. Our results show that an ERK-like protein is involved in the molecular signalling during the interaction between the host and T. crassiceps, and may be considered as target for anti-helminth drugs design.
PMCID: PMC2817376  PMID: 20145710
12.  Jak3 Is Involved in Dendritic Cell Maturation and CCR7-Dependent Migration 
PLoS ONE  2009;4(9):e7066.
CCR7-mediated signalling is important for dendritic cell maturation and homing to the lymph nodes. We have previously demonstrated that Jak3 participates in the signalling pathway of CCR7 in T lymphocytes.
Methodology and Principal Findings
Here, we used Jak3−/− mice to analyze the role of Jak3 in CCR7-mediated dendritic cells migration and function. First, we found no differences in the generation of DCs from Jak3−/− bone marrow progenitors, when compared to wild type cells. However, phenotypic analysis of the bone marrow derived DCs obtained from Jak3−/− mice showed reduced expression of co-stimulatory molecules compared to wild type (Jak3+/+). In addition, when we analyzed the migration of Jak3−/− and Jak3+/+ mature DCs in response to CCL19 and CCL21 chemokines, we found that the absence of Jak3 results in impaired chemotactic responses both in vitro and in vivo. Moreover, lymphocyte proliferation and contact hypersensitivity experiments showed that DC-mediated T lymphocyte activation is reduced in the absence of Jak3.
Altogether, our data provide strong evidence that Jak3 is important for DC maturation, migration and function, through a CCR7-mediated signalling pathway.
PMCID: PMC2738966  PMID: 19759904

Results 1-12 (12)