Andrea Henriques-Pons

INCREASED SUSCEPTIBILITY OF FAS LIGAND-DEFICIENT GLD MICE TO TRYPANOSOMA CRUZI INFECTION DUE TO A TH2-BIASED HOST IMMUNE RESPONSE

Infection of BALB / c mice with Trypanosoma cruzi resulted in up‐regulated expression of Fas and Fas ligand (FasL) mRNA by splenic CD4+ T cells, activation‐induced CD4+ T cell death (AICD), and in Fas  :  FasL‐mediated cytotoxicity. When CD4+ T cells from infected mice were co‐cultured with T. cruzi‐infected macrophages, onset of AICD exacerbated parasite replication. CD4+ T cells from T. cruzi‐infected FasL‐deficient BALB gld / gld mice had no detectable AICD in vitro and their activation with anti‐TCR did not exacerbate T. cruzi replication in macrophages. However, infection of BALB gld / gld mice with T. cruzi resulted in higher and more prolonged parasitemia, compared to wild‐type mice. Secretion of Th2 cytokines IL‐10 and IL‐4 by CD4+ T cells from infected gld mice was markedly increased, compared to controls. In addition, in vivo injection of anti‐IL‐4 mAb, but not of an isotype control mAb, reduced parasitemia in both gld and wild‐type mice. These results indicate that, besides controlling CD4+ T cell AICD and parasite replication in vitro, an intact Fas  :  FasL pathway also controls the host cytokine response to T. cruzi infection in vivo, being required to prevent an exacerbated Th2‐type immune response to the parasite.

Nonimmune mechanisms of muscle damage in myositis: role of the endoplasmic reticulum stress response and autophagy in the disease pathogenesis.

Purpose of reviewRecent literature in inflammatory myopathies suggests that both immune (cell-mediated and humoral) and nonimmune [endoplasmic reticulum (ER) stress and autophagy] mechanisms play a role in muscle fiber damage and dysfunction. This review describes these findings and discusses their relevance to disease pathogenesis and therapy. Recent findingsRecent studies highlight the role of ER stress response, especially the roles of hexose-6-phosphate dehydrogenase and ER-anchored RING finger E3 ligase in the activation of unfolded protein response and the formation of vacuoles and inclusions in myopathies. Several studies investigated the link between inflammation and the β-amyloid-associated muscle fiber degeneration and loss of muscle function. Likewise, the roles of ER stress and autophagy in skeletal muscle damage have been explored in multiple muscle diseases. SummaryCurrent data indicate that the ER stress, nuclear factor-κB pathway and autophagy are active in the skeletal muscle of myositis patients, and the proinflammatory nuclear factor-κB pathway connects the immune and nonimmune pathways of muscle damage. The relative contributions of each of these pathways to muscle fiber damage are currently unclear. Therefore, further defining the role of these pathways in disease pathogenesis should help to design effective therapeutic agents for these diseases.

Role of toll-like receptors in the pathogenesis of dystrophin-deficient skeletal and heart muscle

Although the cause of Duchenne muscular dystrophy (DMD) is known, the specific factors that initiate and perpetuate disease progression are not well understood. We hypothesized that leaky dystrophin-deficient skeletal muscle releases endogenous danger signals (TLR ligands), which bind to Toll-like receptors (TLRs) on muscle and immune cells and activate downstream processes that facilitate degeneration and regeneration in dystrophic skeletal muscle. Here, we demonstrate that dystrophin-deficient mouse muscle cells show increased expression of several cell-surface and endosomal TLRs. In vitro screening identified ssRNA as a relevant endogenous TLR7 ligand. TLR7 activation led to myd88-dependent production of pro-inflammatory cytokines in dystrophin-deficient muscle cells, and cause significant degeneration/regeneration in vivo in mdx mouse muscle. Also, knockout of the central TLR adaptor protein, myd88 in mdx mice significantly improved skeletal and cardiac muscle function. Likewise, proof-of-concept experiments showed that treating young mdx mice with a TLR7/9 antagonist significantly reduced skeletal muscle inflammation and increased muscle force, suggesting that blocking this pathway may have therapeutic potential for DMD.

Brazilian Green Propolis: Effects In Vitro and In Vivo on Trypanosoma cruzi

The composition of a Brazilian green propolis ethanolic extract (Et-Bra) and its effect on Trypanosoma cruzi trypomastigotes and other pathogenic microorganisms have already been reported. Here, we further investigated Et-Bra targets in T. cruzi and its effect on experimental infection of mice. The IC50/4 days for inhibition of amastigote proliferation was 8.5 ± 1.8 μg mL−1, with no damage to the host cells. In epimastigotes Et-Bra induced alterations in reservosomes, Golgi complex and mitochondrion. These effects were confirmed by flow cytometry analysis. In trypomastigotes, Et-Bra led to the loss of plasma membrane integrity. The in vitro studies indicate that Et-Bra interferes in the functionality of the plasma membrane in trypomastigotes and of reservosomes and mitochondrion in epimastigotes. Acutely infected mice were treated orally with Et-Bra and the parasitemia, mortality and GPT, GOT, CK and urea levels were monitored. The extract (25–300 mg kg−1 body weight/day for 10 days) reduced the parasitemia, although not at significant levels; increased the survival of the animals and did not induce any hepatic, muscular lesion or renal toxicity. Since Et-Bra was not toxic to the animals, it could be assayed in combination with other drugs. Et-Bra could be a potential metacyclogenesis blocker, considering its effect on reservosomes, which are an important energy source during parasite differentiation.

Discovering the Cell: An Educational Game about Cell and Molecular Biology.

The role of games within education becomes clearer as students become more active and are able to take decisions, solve problems and react to the results of those decisions. The educational board game Discovering the Cell (Célula Adentro), is based on problem-solving learning. This investigative game attempts to stimulate reasoning and interactivity in the classroom as it challenges students to collect, discuss and interpret clues in order to decipher a scientific question (Case). Here, we describe the conception, development and evaluation of Discovering the Cell. The game was tested with students from public and private high schools in Rio de Janeiro, Brazil. A questionnaire-based analysis demonstrated how students had adopted this strategy. The majority, from both public and private schools, were able to solve a Case, as well as apply the learned content when answering a related question. Taken together, our results indicate the suitability of the game as an alternative strategy to help teach complex cell and molecular biology themes to secondary-level students.

CCL25 induces α₄β₇ integrin-dependent migration of IL-17⁺ γδ T lymphocytes during an allergic reaction.

Herein, we provide evidence that during allergic inflammation, CCL25 induces the selec‐tive migration of IL‐17+ γδ T cells mediated by α4β7 integrin. Intrapleural injection of CCL25 into ovalbumin (OVA)‐immunized C57BL/6 mice triggered the accumulation of γδ T lymphocytes expressing CCR9 (CCL25 receptor) and α4β7 integrin in the pleura, but failed to attract αβ T lymphocytes. CCL25 attracted CCR6+ γδ T cells producing IL‐17 (but not IFN‐γ or IL‐4). OVA challenge triggered increased production of CCL25 followed by the accumulation of CCR9+, α4β7+, and CCR6+/IL‐17+ γδ T cells into the pleural cavities of OVA‐immunized mice, which was inhibited by the in vivo neutralization of CCL25. The in vivo blockade of α4β7 integrin also inhibited the migration of IL‐17+ γδ T lymphocytes (but not of αβ T lymphocytes) into mouse pleura after OVA challenge, suggesting that the CCL25/α4β7 integrin pathway is selective for γδ T cells. In addition, α4β7 integrin blockade impaired the in vitro transmigration of γδ T cells across endothelium (which expresses α4β7 ligands VCAM‐1 and MadCAM‐1), which was induced by CCL25 and by cell‐free pleural washes recovered from OVA‐challenged mice. Our results reveal that during an allergic reaction, CCL25 drives IL‐17+ γδ T‐cell mobilization to inflamed tissue via α4β7 integrin and modulates IL‐17 levels.

Mast cell function and death in Trypanosoma cruzi infection

Although the roles of mast cells (MCs) are essential in many inflammatory and fibrotic diseases, their role in Trypanosoma cruzi-induced cardiomyopathy is unexplored. In this study, we treated infected CBA mice with cromolyn, an MC stabilizer, and observed much greater parasitemia and interferon-γ levels, higher mortality, myocarditis, and cardiac damage. Although these data show that MCs are important in controlling acute infection, we observed MC apoptosis in the cardiac tissue and peritoneal cavity of untreated mice. In the heart, pericardial mucosal MC die, perhaps because of reduced amounts of local stem cell factor. Using RT-PCR in purified cardiac MCs, we observed that infection induced transcription of P2X(7) receptor and Fas, two molecules reportedly involved in cell death and inflammatory regulation. In gld/gld mice (FasL(-/-)), apoptosis of cardiac, but not peritoneal, MCs was decreased. Conversely, infection of P2X(7)(-/-) mice led to reduced peritoneal, but not cardiac, MC death. These data illustrate the immunomodulatory role played by MCs in T. cruzi infection and the complexity of molecular interactions that control inflammatory pathways in different tissues and compartments.

P2X7 modulatory web in Trypanosoma cruzi infection

P2X7 is a member of the purinergic receptors family, with extracellular adenosine triphosphate (ATP) as the main agonist, promoting cations influx and membrane permeabilization that can lead to cell death. We previously proposed that extracellular ATP is involved in thymus atrophy induced by Trypanosoma cruzi infection through the induction of CD4+/CD8+ double-positive cell death and that P2X7 could be involved in this process. To further elucidate this possibility raised by in vitro assays, in this study, we used

Absence of Fas-L aggravates renal injury in acute Trypanosoma cruzi infection

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