B cells from Patients with Rheumatoid Arthritis Show Conserved CD39-Mediated Regulatory Function and increased CD39 Expression After Positive Response to Therapy.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by progressive joint destruction associated with increased pro-inflammatory mediators. In inflammatory microenvironments, exogenous ATP (eATP) is hydrolyzed to adenosine, which exerts immunosuppressive effects, by the consecutive action of the ectonucleotidases CD39 and CD73. Mature B cells constitutively express both ectonucleotidases, converting these cells to potential suppressors. Here, we assessed CD39 and CD73 expression on B cells from treated or untreated patients with RA. Neither the frequency of CD73+CD39+ and CD73-CD39+ B cell subsets nor the levels of CD73 and CD39 expression on B cells from untreated or treated RA patients showed significant changes in comparison to healthy controls (HC). CpG+IL-2-stimulated B cells from HC or untreated RA patients increased their CD39 expression, and suppressed CD4+ and CD8+ T cell proliferation and intracellular TNF-production. A CD39 inhibitor significantly restored proliferation and TNF-producing capacity in CD4+ T cells, but not in CD8+ T cells, from HC and untreated RA patients, indicating that B cells from untreated RA patients conserved CD39-mediated regulatory function. Good responder patients to therapy (R-RA) exhibited an increased CD39 but not CD73 expression on B cells after treatment, while most of the non-responder (NR) patients showed a reduction in ectoenzyme expression. The positive changes of CD39 expression on B cells exhibited a negative correlation with disease activity and rheumatoid factor levels. Our results suggest modulating the ectoenzymes/ADO pathway as a potential therapy target for improving the course of RA.

Tumor-induced senescent T cells promote the secretion of pro-inflammatory cytokines and angiogenic factors by human monocytes/macrophages through a mechanism that involves Tim-3 and CD40L.

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-1ß 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.

Trypanosoma cruzi infection beats the B-cell compartment favouring parasite establishment: can we strike first?

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.

B cells from aged mice exhibit reduced apoptosis upon B-cell antigen receptor stimulation and differential ability to up-regulate survival signals.

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.

Interleukin-4 biases differentiation of B cells from Trypanosoma cruzi-infected mice and restrains their fratricide: role of Fas ligand down-regulation and MHC class II-transactivator up-regulation.

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.