Jorge Postigo

Exacerbation of type II collagen–induced arthritis in apolipoprotein E–deficient mice in association with the expansion of Th1 and Th17 cells

OBJECTIVE To explore the bidirectional relationship between the development of rheumatoid arthritis (RA) and atherosclerosis using bovine type II collagen (CII)-immunized B10.RIII apoE(-/-) mice, a murine model of spontaneous atherosclerosis and collagen-induced arthritis (CIA). METHODS Male B10.RIII apoE(-/-) mice and wild-type controls were immunized with 150 μg of CII emulsified in Freunds complete adjuvant (CFA). The clinical, radiologic, and histopathologic severity of CIA, the levels of circulating IgG1 and IgG2a anti-CII antibodies, the expression of proinflammatory and antiinflammatory cytokines in the joints, and the percentages of Th1, Th17, and Treg lymphocytes in the draining lymph nodes were evaluated during CIA induction. In addition, the size of atherosclerotic lesions was assessed in these mice 8 weeks after CIA induction. RESULTS B10.RIII apoE(-/-) mice that were immunized with CII and CFA developed an exacerbated CIA that was accompanied by increased joint expression of multiple proinflammatory cytokines and by the expansion in the draining lymph nodes of Th1 and Th17 cells. In contrast, the size of vascular lesions in B10.RIII apoE(-/-) mice was not affected by the development of CIA. CONCLUSION Our findings indicate that a deficiency in apolipoprotein E and/or its consequences in cholesterol metabolism act as accelerating factors in autoimmunity by promoting Th1 and Th17 inflammatory responses.

Mice deficient in CD38 develop an attenuated form of collagen type II-induced arthritis

CD38, a type II transmembrane glycoprotein expressed in many cells of the immune system, is involved in cell signaling, migration and differentiation. Studies in CD38 deficient mice (CD38 KO mice) indicate that this molecule controls inflammatory immune responses, although its involvement in these responses depends on the disease model analyzed. Here, we explored the role of CD38 in the control of autoimmune responses using chicken collagen type II (col II) immunized C57BL/6-CD38 KO mice as a model of collagen-induced arthritis (CIA). We demonstrate that CD38 KO mice develop an attenuated CIA that is accompanied by a limited joint induction of IL-1β and IL-6 expression, by the lack of induction of IFNγ expression in the joints and by a reduction in the percentages of invariant NKT (iNKT) cells in the spleen. Immunized CD38 KO mice produce high levels of circulating IgG1 and low of IgG2a anti-col II antibodies in association with reduced percentages of Th1 cells in the draining lymph nodes. Altogether, our results show that CD38 participates in the pathogenesis of CIA controlling the number of iNKT cells and promoting Th1 inflammatory responses.

Involvement of the intrinsic and extrinsic cell-death pathways in the induction of apoptosis of mature lymphocytes by the Escherichia coli heat-labile enterotoxin

Escherichia coli heat‐labile enterotoxin (LT) exhibits a broad range of immunomodulatory activities, including the induction of lymphocyte‐programmed cell death. In previous studies, we have demonstrated that in vivo LT promotes apoptosis of immature T and B cells through the stimulation of endogenous glucocorticoids. In the present study, we show that the extrinsic cell‐death pathway as well as the apoptosis‐inducing factor do not participate in the LT‐induced elimination of thymocytes. In contrast to developing lymphocytes, LT promotes the death of mature lymphocytes by both glucocorticoid‐ and Fas death receptor/Fas ligand‐dependent mechanisms. However, the dependency of these mechanisms in the LT‐induced cell‐death activity seems to be different among CD4+ and CD8+ T cells. Altogether, our study shows that the same bacterial toxin can induce apoptosis of lymphoid cells through several mechanisms depending on the status of differentiation of these cells.

p27Kip1 inhibits systemic autoimmunity through the control of Treg cell activity and differentiation

OBJECTIVE Despite the importance of Treg cells in the maintenance of immunologic tolerance, the mechanisms that control their generation and activity are unknown. Since the cell cycle inhibitor p27(Kip1) (p27) was involved in T cell anergy, we undertook this study to explore its role in both Treg cell processes. METHODS The development of type II collagen-induced arthritis (CIA) and lupus-like abnormalities was compared between transgenic mice overexpressing human Bcl-2 in T cells (BCL2-TgT mice) and nontransgenic mice that were deficient or not deficient in p27. The contribution of Treg cells to disease evolution was also explored. Finally, the in vitro activity of Treg cells and their differentiation from naive CD4+ cells was compared between these strains of mice. RESULTS BCL2-TgT mice were protected against CIA by a Treg cell-dependent mechanism. In association with this protection, the overexpression of Bcl-2 in T cells enhanced the differentiation and activity of Treg cells. Both Bcl-2 effects were independent of its antiapoptotic activity but dependent on its capacity to induce the expression of p27 that augmented the strength of transforming growth factor β (TGFβ) signaling in T cells. Accordingly, down-modulation of p27 expression in BCL2-TgT mice promoted CIA. In addition, p27 deficiency in aged C57BL/6 mice reduced the number and activity of Treg cells and induced the development of mild lupus-like abnormalities. CONCLUSION Our results point to p27 as a critical regulator of Treg cell differentiation and function through the positive modulation of TGFβ signaling strength in T cells.

Identification of multiple transferrin species in the spleen and serum from mice with collagen-induced arthritis which may reflect changes in transferrin glycosylation associated with disease activity: The role of CD38.

UNLABELLED Collagen type II-induced arthritis (CIA) is an inflammatory and autoimmune disease. Spleen protein extracts were subjected to 2D-DiGE and MS-MALDI-TOF/TOF analysis to identify protein species that differ in abundance in CD38-KO versus B6 WT mice either with arthritis or with inflammation. Using multivariate analyses, in Col-II-immunized mice, 23 distinct spleen protein species were able to discriminate between WT and CD38-KO mice. Among them, several citrullinated proteins and multiple serotransferrin (Tf) species were identified. In contrast, in CFA/IFA-treated mice, the distinct protein profile, which discriminates between CD38-KO and WT mice, was unrelated with Tf, but not with citrullination. Unexpectedly, non-immunized CD38-KO mice showed a distinct proteome profile as compared with that in non-immunized WT mice, and again multiple protein species were identified as Tf. By using a μLC-TOF-MS method to separate and detect Tf glycopeptide glycoforms, increases in fucosylation and glycan branching was observed in sera from mice CIA(+) versus non-immunized, and between WT and CD38-KO with arthritis. Data on 2-DE Tf spots indicated differences in glycosylation related with NeuGc content. Thus, Tf changed significantly in its glycosylation pattern in arthritic mice. The MS data have been deposited to the ProteomeXchange Consortium with the dataset identifiers: PXD002644, PXD002643, PXD003183, and PXD003163. SIGNIFICANCE 2-DE followed by μLC-TOF-MS could be implemented to identify Tf glycoforms linked to specific protein species, and correlate a particular Tf species to a function. To gain insight into the relationship between transferrin glycoforms and its biological function it is particularly interesting to study putative differences in the glycosylation pattern of Tf in specific tissues associated with the disease (i.e.: joints), or in specific compartments such as exosomes/microvesicles, which are highly enriched in Tf receptors.

Transgenic expression of soluble human CD5 enhances experimentally-induced autoimmune and anti-tumoral immune responses

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.

Bone Morphogenetic Protein and Activin Membrane–Bound Inhibitor, a Transforming Growth Factor β Rheostat That Controls Murine Treg Cell/Th17 Cell Differentiation and the Development of Autoimmune Arthritis by Reducing Interleukin-2 Signaling

Transforming growth factor β (TGFβ) plays a prominent role in the establishment of immunologic tolerance, and mice lacking TGFβ1 die of multiorgan inflammation early in life. TGFβ controls the differentiation of CD4+ lymphocytes into Treg cells or proinflammatory Th17 cells. Although this dual capacity is modulated by the presence of additional cytokines around the activated cells, TGFβ also dissociates Th17/Treg cell differentiation in a dose‐dependent manner by mechanisms still unknown. The purpose of this study was to explore the contribution of bone morphogenetic protein and activin membrane–bound inhibitor (BAMBI) to the modulation of TGFβ activity during the differentiation of CD4+ cells and in the control of immunologic tolerance in mice with collagen‐induced arthritis (CIA).

Distinct serum proteome profiles associated with collagen-induced arthritis and complete Freund's adjuvant-induced inflammation in CD38-/- mice: The discriminative power of protein species or proteoforms

Collagen‐type‐II‐induced arthritis (CIA) is an autoimmune disease, which involves a complex host systemic response including inflammatory and autoimmune reactions. CIA is milder in CD38−/− than in wild‐type (WT) mice. ProteoMiner‐equalized serum samples were subjected to 2D‐DiGE and MS‐MALDI‐TOF/TOF analyses to identify proteins that changed in their relative abundances in CD38−/− versus WT mice either with arthritis (CIA+), with no arthritis (CIA−), or with inflammation (complete Freunds adjuvant (CFA)‐treated mice). Multivariate analyses revealed that a multiprotein signature (n = 28) was able to discriminate CIA+ from CIA− mice, and WT from CD38−/− mice within each condition. Likewise, a distinct multiprotein signature (n = 16) was identified which differentiated CIA+ CD38−/− mice from CIA+ WT mice, and lastly, a third multiprotein signature (n = 18) indicated that CD38−/− and WT mice could be segregated in response to CFA treatment. Further analyses showed that the discriminative power to distinguish these groups was reached at protein species level and not at the protein level. Hence, the need to identify and quantify proteins at protein species level to better correlate proteome changes with disease processes. It is crucial for plasma proteomics at the low‐abundance protein species level to apply the ProteoMiner enrichment. All MS data have been deposited in the ProteomeXchange with identifiers PXD001788, PXD001799 and PXD002071 (http://proteomecentral.proteomexchange.org/dataset/PXD001788, http://proteomecentral.proteomexchange.org/dataset/PXD001799 and http://proteomecentral.proteomexchange.org/dataset/PXD002071).

BAMBI a TGFβ rheostat that controls regulatory T/TH17 differentiation and the development of autoimmune arthritis by reducing IL‐2 signaling

Transforming growth factor β (TGFβ) plays a prominent role in the establishment of immunologic tolerance, and mice lacking TGFβ1 die of multiorgan inflammation early in life. TGFβ controls the differentiation of CD4+ lymphocytes into Treg cells or proinflammatory Th17 cells. Although this dual capacity is modulated by the presence of additional cytokines around the activated cells, TGFβ also dissociates Th17/Treg cell differentiation in a dose‐dependent manner by mechanisms still unknown. The purpose of this study was to explore the contribution of bone morphogenetic protein and activin membrane–bound inhibitor (BAMBI) to the modulation of TGFβ activity during the differentiation of CD4+ cells and in the control of immunologic tolerance in mice with collagen‐induced arthritis (CIA).

GITR contributes to the systemic adjuvanticity of the Escherichia coli heat-labile enterotoxin

The Escherichia coli heat‐labile enterotoxin (LT) possesses a powerful mucosal and systemic adjuvant effect. However, little is known about the cellular and molecular basis of the immunostimulatory activity of LT at the mucosal level, and even less information is available on the mechanisms underlying its systemic adjuvant activity. In this study, we show that distinct mechanisms are responsible for the parenteral and mucosal adjuvanticity of LT. Indeed, the systemic administration of LT upregulates the expression of glucocorticoid‐induced TNFR‐related protein (GITR), but not other activation markers, in naive T cells. Using WT and GITR‐deficient mice and LT and its enzymatically inactive mutant LTK63 as adjuvants, we show that the induction of GITR expression in T cells accounts for the systemic immunostimulatory capacity of LT, which requires an intact enzymatic activity. In contrast, the mucosal administration of LT does not induce GITR expression on Peyers patche T cells and accordingly no differences are observed in the mucosal adjuvanticity of LT between WT and GITR‐deficient mice. Altogether, our results demonstrate the distinct effect of LT after parenteral administration when compared with the mucosal delivery, and describe a new mechanism of LT adjuvanticity related to its ability to induce the expression of GITR in CD4+ T cells.