Viabilidade e segurança do transplante intratecal de células-tronco mesenquimais autólogas e alogênicas provenientes da medula óssea de cães (lupus canis familiaris)

Pós-graduação em Medicina Veterinária - FMVZ

Atuação da ocitocina no processo de diferenciação osteoblástica de ratas senis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

In vivo assessment of genotoxic, antigenotoxic and anticarcinogenic activities of Solanum lycocarpum fruits glycoalkaloidic extract

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Impairment of the hematological response and interleukin-1β production in protein-energy malnourished mice after endotoxemia with lipopolysaccharide

The objectives of this study were to determine if protein-energy malnutrition (PEM) could affect the hematologic response to lipopolysaccharide (LPS), the interleukin-1β (IL-1β) production, leukocyte migration, and blood leukocyte expression of CD11a/CD18. Two-month-old male Swiss mice were submitted to PEM (N = 30) with a low-protein diet (14 days) containing 4% protein, compared to 20% protein in the control group (N = 30). The total cellularity of blood, bone marrow, spleen, and bronchoalveolar lavage evaluated after the LPS stimulus indicated reduced number of total cells in all compartments studied and different kinetics of migration in malnourished animals. The in vitro migration assay showed reduced capacity of migration after the LPS stimulus in malnourished animals (45.7 ± 17.2 x 10(4) cells/mL) compared to control (69.6 ± 7.1 x 10(4) cells/mL, P ≤ 0.05), but there was no difference in CD11a/CD18 expression on the surface of blood leukocytes. In addition, the production of IL-1β in vivo after the LPS stimulus (180.7 pg·h-1·mL-1), and in vitro by bone marrow and spleen cells (41.6 ± 15.0 and 8.3 ± 4.0 pg/mL) was significantly lower in malnourished animals compared to control (591.1 pg·h-1·mL-1, 67.0 ± 23.0 and 17.5 ± 8.0 pg/mL, respectively, P ≤ 0.05). The reduced expression of IL-1β, together with the lower number of leukocytes in the central and peripheral compartments, different leukocyte kinetics, and reduced leukocyte migration capacity are factors that interfere with the capacity to mount an adequate immune response, being partly responsible for the immunodeficiency observed in PEM.

Impiego di cellule staminali in terapia veterinaria

Over the past few years, in veterinary medicine there has been an increased interest in understanding the biology of mesenchymal stem cells (MSCs). This interest comes from their potential clinical use especially in wound repair, tissue engineering and application in therapeutics fields, including regenerative surgery. MSCs can be isolated directly from bone marrow aspirates, adipose tissue, umbilical cord and various foetal tissues. In this study, mesenchymal stem cells were isolated from equine bone marrow, adipose tissue, cord blood, Wharton’s Jelly and, for the first time, amniotic fluid. All these cell lines underwent in vitro differentiation in chondrocytes, osteocytes and adipocytes. After molecular characterization, cells resulted positive for mesenchymal markers such as CD90, CD105, CD44 and negative for CD45, CD14, CD34 and CD73. Adipose tissue and bone marrow mesenchymal stem cells were successfully applied in the treatment of tendinitis in race horses. Furthermore, for the first time in the horse, skin wounds of septicemic foal, were treated applying amniotic stem cells. Finally, results never reported have been obtained in the present study, isolating mesenchymal stem cells from domestic cat foetal fluid and membranes. All cell lines underwent in vitro differentiation and expressed mesenchymal molecular markers.

Rolle der gemeinsamen Expression von AML1-ETO und weiteren Onkogenen für die Induktion von Leukämie

Akute Leukämien treten in allen Altersstufen auf. Akute lymphatische Leukämie (ALL) ist die häufigste Leukämie bei Kindern, während akute myeloischen Leukämien (AML) mit verschiedenen Untergruppen etwa 80% aller akuten Leukämien bei Erwachsenen ausmachen. Die Translokation t(8;21) resultiert in der Entstehung des Fusionsgens AML1-ETO und zählt zu den häufigen Translokationen bei der AML. Dabei fusioniert die DNA-bindende Domäne des AML1 mit dem fast kompletten ETO-Protein. AML1-ETO wirkt als dominanter Repressor der AML1-vermittelten transkriptionellen Regula-tion wichtiger hämatopoetischer Zielgene. Klinische Daten legen nahe, dass trotz der klarer Assoziation zwischen AML und der t(8;21) Translokation bei AML Patienten zusätzliche genetische Veränderungen – so genannte ‚second hits‘ – notwendig sind, um eine Leukämie effizient zu induzieren. Klinisch relevanten Komplimentationsonkogene sind unter anderen die aktivierte Rezeptortyrosinkinase FLT3, JAK2, NRAS, KRAS, c- KIT.rnZiel der vorliegenden Arbeit war es, ein Mausmodell zu etablieren, welches humane akute myeloische Leukämie rekapituliert und bei dem die Expression der entsprechen-den Onkogene reguliert werden kann. Als erstes wurde untersucht, ob eine gemeinsame Expression von AML1-ETO mit kRASG12D zur Induktion von Leukämie führen kann. Hierfür wurden Tiere generiert die gemeinsam AML1-ETO und kRASG12D unter der regulatorischen Sequenz des Tetrazyklin-Operators exprimierten. Der große Vorteil dieser Technologie ist die regulierbare Reversibilität der Genexpression. Um die Ex-pression der Zielgene auf blutbildende Zellen zu beschränken, wurden Knochenmark-chimären hergestellt. Im Beobachtungszeitraum von 12 Monaten führte die Expression von AML1-ETO und AML1-ETO/kRASG12D nicht zur Induktion einer akuten Leukä-mie. Die normale hämatopoetische Entwicklung war jedoch in diesen Tieren gestört. Der beobachtete Phänotyp entsprach einem myelodysplastischen Syndrome (MDS).rnIm zweiten Ansatz, wurden Tiere generiert die gemeinsam AML1-ETO und FLT3-ITD exprimierten. Hierfür wurden hämatopoetische Stammzellen aus ROSA26-iM2/tetO-AML1-ETO isoliert und mit Hilfe des retroviralen Vektors mit FLT3-ITD transduziert. In diesem Modell war es möglich, in kurzer Zeit eine akute Leukämie mit zu induzieren. Einige wenige Tiere hatten zum Zeitpunkt des Todes Anzeichen einer biphänotypischen Leukämie mit lymphatischen und myeloischen Blastenpopulationen. In drei Tieren in-duzierte die alleinige Expression von FLT3-ITD eine Leukämie. Alle Leukämien wurden durch FACS, Zytologie und Histopathologie bestätigt. Knochenmark- bzw. Milzzellen aus den erkrankten Tieren waren in der Lage nach Transfer in sekundäre Rezipienten eine Leukämie auszulösen. Somit besaßen sie ein uneingeschränktes Selbsterneue-rungspotential.rnEin erster Versuch, in dem AML1-ETO Expression in leukämischen Zellen abgeschaltet und FLT3-ITD mit Tyrosinkinase-Inhibitor inhibiert wurde, zeigte keine wesentliche Veränderung in der Leukämieprogression.rnDieses Leukämiemodell erlaubt die Rolle der beteiligten Onkogene während verschie-dener Stadien der Leukämie zu erforschen und damit möglicherweise neue Ansätze für Therapiestrategien zu entwickeln.

Tumor necrosis factor-alpha: alternative role as an inhibitor of osteoclast formation in vitro

TNFalpha is known to stimulate the development and activity of osteoclasts and of bone resorption. The cytokine was found to mediate bone loss in conjunction with inflammatory diseases such as rheumatoid arthritis or chronic aseptic inflammation induced by wear particles from implants and was suggested to be a prerequisite for the loss of bone mass under estrogen deficiency. In the present study, the regulation of osteoclastogenesis by TNFalpha was investigated in co-cultures of osteoblasts and bone marrow or spleen cells and in cultures of bone marrow and spleen cells grown with CSF-1 and RANKL. Low concentrations of TNFalpha (1 ng/ml) caused a >90% decrease in the number of osteoclasts in co-cultures, but did not affect the development of osteoclasts from bone marrow cells. In cultures with p55TNFR(-/-) osteoblasts and wt BMC, the inhibitory effect was abrogated and TNFalpha induced an increase in the number of osteoclasts in a dose-dependent manner. Osteoblasts were found to release the inhibitory factor(s) into the culture supernatant after simultaneous treatment with 1,25(OH)(2)D(3) and TNFalpha, this activity, but not its release, being resistant to treatment with anti-TNFalpha antibodies. Dexamethasone blocked the secretion of the TNFalpha-dependent inhibitor by osteoblasts, while stimulating the development of osteoclasts. The data suggest that the effects of TNFalpha on the differentiation of osteoclast lineage cells and on bone metabolism may be more complex than hitherto assumed and that these effects may play a role in vivo during therapies for inflammatory diseases.

Mutations in the cofilin partner Aip1/Wdr1 cause autoinflammatory disease and macrothrombocytopenia.

A pivotal mediator of actin dynamics is the protein cofilin, which promotes filament severing and depolymerization, facilitating the breakdown of existing filaments, and the enhancement of filament growth from newly created barbed ends. It does so in concert with actin interacting protein 1 (Aip1), which serves to accelerate cofilin's activity. While progress has been made in understanding its biochemical functions, the physiologic processes the cofilin/Aip1 complex regulates, particularly in higher organisms, are yet to be determined. We have generated an allelic series for WD40 repeat protein 1 (Wdr1), the mammalian homolog of Aip1, and report that reductions in Wdr1 function produce a dramatic phenotype gradient. While severe loss of function at the Wdr1 locus causes embryonic lethality, macrothrombocytopenia and autoinflammatory disease develop in mice carrying hypomorphic alleles. Macrothrombocytopenia is the result of megakaryocyte maturation defects, which lead to a failure of normal platelet shedding. Autoinflammatory disease, which is bone marrow-derived yet nonlymphoid in origin, is characterized by a massive infiltration of neutrophils into inflammatory lesions. Cytoskeletal responses are impaired in Wdr1 mutant neutrophils. These studies establish an essential requirement for Wdr1 in megakaryocytes and neutrophils, indicating that cofilin-mediated actin dynamics are critically important to the development and function of both cell types.

Sheep macrophages express at least two distinct receptors for IgG which have similar affinity for homologous IgG1 and IgG2.

Ovine bone marrow-derived macrophages (BMM) may express several IgG receptor (Fc gamma receptor; FcR) subsets. To study this, model particles (opsonized erythrocytes; EA), which are selectively handled by certain FcR subsets of human macrophages were used in cross-inhibition studies and found to react in a similar manner with FcR subsets of sheep macrophages. In experiments with monoclonal antibodies against subsets of human FcR, human erythrocytes (E) treated with human anti-D-IgG (anti-D-EAhu) and sheep E treated with bovine IgG1 (Bo1-EAs) were handled selectively by human macrophage FcRI and FcRII, respectively. Rabbit-IgG-coated sheep E (Rb-EAs) were recognized by FcRI, FcRII and possibly also by FcRIII of human macrophages. Anti-D-EAhu, Bo1-EAs and Rb-EAs were also ingested by sheep BMM. Competitive inhibition tests, using various homologous and heterologous IgG isotypes as fluid phase inhibitors and the particles used as FcR-specific tools in man (anti-D-EAhu and Bo1-EAs), revealed a heterogeneity of FcR also in sheep BMM. Thus, ingestion of anti-D-EAhu by ovine BMM was inhibited by low concentrations of competitor IgG from rabbit or man in the fluid phase, but not at all by bovine IgG1, whereas ingestion of Bo1-EAs was inhibited by bovine IgG1. This suggested that anti-D-EAhu were recognized by a FcR subset distinct from that recognizing bovine-IgG1. It was concluded that sheep BMM express functional analogs of human macrophage FcRI and FcRII and that Bo1-EAs and anti-D-EAhu are handled by distinct subsets of BMM FcR. All EAhu tested (EAhu treated with anti-D, sheep IgG1 or sheep IgG2) were ingested to a lower degree than EAs. This inefficient phagocytosis could be enhanced by treatment of EAhu with antiglobulin from the rabbit, suggesting that it is caused by a low degree of activity of opsonizing antibodies rather than special properties of the erythrocytes themselves. Several lines of evidence suggested that both FcR subsets of ovine BMM recognize both ovine IgG1 and IgG2. In contrast, bovine IgG1 reacts with one FcR subset and bovine IgG2 interacts inefficiently with all FcR of ovine BMM.

Helicobacter pylori Inhibits Dendritic Cell Maturation via Interleukin-10-Mediated Activation of the Signal Transducer and Activator of Transcription 3 Pathway.

Helicobacter pylori infects the human gastric mucosa causing a chronic infection that is the primary risk factor for gastric cancer development. Recent studies demonstrate that H. pylori promotes tolerogenic dendritic cell (DC) development indicating that this bacterium evades the host immune response. However, the signaling pathways involved in modulating DC activation during infection remain unclear. Here, we report that H. pylori infection activated the signal transducer and activator of transcription 3 (STAT3) pathway in murine bone marrow-derived DCs (BMDCs) and splenic DCs isolated ex vivo. Isogenic cagA-, cagE-, vacA- and urease-mutants exhibited levels of phosphoSTAT3 that were comparable to in the wild-type (WT) parent strain. H. pylori-infected BMDCs produced increased immunosuppressive IL-10, which activated STAT3 in an autocrine/paracrine fashion. Neutralization of IL-10 prevented H. pylori-mediated STAT3 activation in both BMDCs and splenic DCs. In addition, anti-IL-10 treatment of infected H. pylori-BMDCs was associated with increased CD86 and MHC II expression and enhanced proinflammatory IL-1β cytokine secretion. Finally, increased CD86 and MHC II expression was detected in H. pylori-infected STAT3 knockout DCs when compared to WT controls. Together, these results demonstrate that H. pylori infection induces IL-10 secretion in DCs, which activates STAT3, thereby modulating DC maturation and reducing IL-1β secretion. These findings identify a host molecular mechanism by which H. pylori can manipulate the innate immune response to potentially favor chronic infection and promote carcinogenesis. © 2014 S. Karger AG, Basel.

Size-dependent accumulation of particles in lysosomes modulates dendritic cell function through impaired antigen degradation.

INTRODUCTION Nanosized particles may enable therapeutic modulation of immune responses by targeting dendritic cell (DC) networks in accessible organs such as the lung. To date, however, the effects of nanoparticles on DC function and downstream immune responses remain poorly understood. METHODS Bone marrow-derived DCs (BMDCs) were exposed in vitro to 20 or 1,000 nm polystyrene (PS) particles. Particle uptake kinetics, cell surface marker expression, soluble protein antigen uptake and degradation, as well as in vitro CD4(+) T-cell proliferation and cytokine production were analyzed by flow cytometry. In addition, co-localization of particles within the lysosomal compartment, lysosomal permeability, and endoplasmic reticulum stress were analyzed. RESULTS The frequency of PS particle-positive CD11c(+)/CD11b(+) BMDCs reached an early plateau after 20 minutes and was significantly higher for 20 nm than for 1,000 nm PS particles at all time-points analyzed. PS particles did not alter cell viability or modify expression of the surface markers CD11b, CD11c, MHC class II, CD40, and CD86. Although particle exposure did not modulate antigen uptake, 20 nm PS particles decreased the capacity of BMDCs to degrade soluble antigen, without affecting their ability to induce antigen-specific CD4(+) T-cell proliferation. Co-localization studies between PS particles and lysosomes using laser scanning confocal microscopy detected a significantly higher frequency of co-localized 20 nm particles as compared with their 1,000 nm counterparts. Neither size of PS particle caused lysosomal leakage, expression of endoplasmic reticulum stress gene markers, or changes in cytokines profiles. CONCLUSION These data indicate that although supposedly inert PS nanoparticles did not induce DC activation or alteration in CD4(+) T-cell stimulating capacity, 20 nm (but not 1,000 nm) PS particles may reduce antigen degradation through interference in the lysosomal compartment. These findings emphasize the importance of performing in-depth analysis of DC function when developing novel approaches for immune modulation with nanoparticles.

CD8 T cell ignorance or tolerance to islet antigens depends on antigen dose

There are two major mechanisms reported to prevent the autoreactivity of islet-specific CD8+ T cells: ignorance and tolerance. When ignorance is operative, naïve autoreactive CD8+ T cells ignore islet antigens and recirculate without causing damage, unless activated by an external stimulus. In the case of tolerance, CD8+ T cells are deleted. Which factor(s) contributes to each particular outcome was previously unknown. Here, we demonstrate that the concentration of self antigen determines which mechanism operates. When ovalbumin (OVA) was expressed at a relatively low concentration in the pancreatic islets of transgenic mice, there was no detectable cross-presentation, and the CD8+ T cell compartment remained ignorant of OVA. In mice expressing higher doses of OVA, cross-presentation was detectable and led to peripheral deletion of OVA-specific CD8+ T cells. When cross-presentation was prevented by reconstituting the bone marrow compartment with cells incapable of presenting OVA, deletional tolerance was converted to ignorance. Thus, the immune system uses two strategies to avoid CD8+ T cell-mediated autoimmunity: for high dose antigens, it deletes autoreactive T cells, whereas for lower dose antigens, it relies on ignorance.

Two highly homologous ribonuclease genes expressed in mouse eosinophils identify a larger subgroup of the mammalian ribonuclease superfamily.

Two putative ribonucleases have been isolated from the secondary granules of mouse eosinophils. Degenerate oligonucleotide primers inferred from peptide sequence data were used in reverse transcriptase-PCR reactions of bone marrow-derived cDNA. The resulting PCR product was used to screen a C57BL/6J bone marrow cDNA library, and comparisons of representative clones showed that these genes and encoded proteins are highly homologous (96% identity at the nucleotide level; 92/94% identical/similar at the amino acid level). The mouse proteins are only weakly homologous (approximately 50% amino acid identity) with the human eosinophil-associated ribonucleases (i.e., eosinophil-derived neurotoxin and eosinophil cationic protein) and show no sequence bias toward either human protein. Phylogenetic analyses established that the human and mouse loci shared an ancestral gene, but that independent duplication events have occurred since the divergence of primates and rodents. The duplication event generating the mouse genes was estimated to have occurred < 5 x 10(6) years ago (versus 30 to 40 x 10(6) years ago in primates). The identification of independent duplication events in two extant mammalian orders suggests a selective advantage to having multiple eosinophil granule ribonucleases. Southern blot analyses in the mouse demonstrated the existence of three additional highly homologous genes (i.e., five genes total) as well as several more divergent family members. The potential significance of this observation is the implication of a larger gene subfamily in primates (i.e., humans).

Human cytomegalovirus latent gene expression in granulocyte-macrophage progenitors in culture and in seropositive individuals.

Following infection with cytomegalovirus, human granulocyte-macrophage progenitors carry the viral genome but fail to support productive replication. Viral transcripts arise from a region encompassing the major regulatory gene locus; however, their structure differs significantly from productive phase transcripts. One class, sense transcripts, is encoded in the same direction as productive phase transcripts but uses two novel start sites in the ie1/ie2 promoter/enhancer region. These transcripts have the potential to encode a novel 94 aa protein. The other class, antisense transcript, is unspliced and complimentary to ie1 exons 2-4, and has the potential to encode novel 154 and 152 aa proteins. Consistent with a role in latency, these transcripts are present in bone marrow aspirates from naturally infected, healthy seropositive donors but are not present in seronegative controls. Sense latent transcripts are present in a majority of seropositive individuals. Consistent with the expression of latent transcripts, antibody to the 94 aa and 152 aa proteins is detectable in the serum of seropositive individuals. Thus, latent infection by cytomegalovirus is accompanied by the presence of latency-associated transcripts and expression of immunogenic proteins. Overall, these results suggest that bone marrow-derived myeloid progenitors are an important natural site of viral latency.

Fatores de risco para a progressão da gamapatia monoclonal de significado indeterminado para mieloma múltiplo

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014