G-CSF-Induced Suppressor IL-10+ Neutrophils Promote Regulatory T Cells That Inhibit Graft-Versus-Host Disease in a Long-Lasting and Specific Way.

Acute graft-versus-host disease (aGVHD) is the main complication of allogeneic hematopoietic stem cell transplantation, and many efforts have been made to overcome this important limitation. We showed previously that G-CSF treatment generates low-density splenic granulocytes that inhibit experimental aGVHD. In this article, we show that aGVHD protection relies on incoming IL-10+ neutrophils from G-CSF-treated donor spleen (G-Neutrophils). These G-Neutrophils have high phagocytic capacity, high peroxide production, low myeloperoxidase activity, and low cytoplasmic granule content, which accounts for their low density. Furthermore, they have low expression of MHC class II, costimulatory molecules, and low arginase1 expression. Also, they have low IFN-γ, IL-17F, IL-2, and IL-12 levels, with increased IL-10 production and NO synthase 2 expression. These features are in accordance with the modulatory capacity of G-Neutrophils on regulatory T cell (Treg) generation. In vivo, CD25+ Treg depletion shortly after transplantation with splenic cells from G-CSF-treated donors blocks suppression of aGVHD, suggesting Treg involvement in the protection induced by the G-Neutrophils. The immunocompetence and specificity of the semiallogeneic T cells, long-term after the bone marrow transplant using G-Neutrophils, were confirmed by third-party skin graft rejection; importantly, a graft-versus-leukemia assay showed that T cell activity was maintained, and all of the leukemic cells were eliminated. We conclude that G-CSF treatment generates a population of activated and suppressive G-Neutrophils that reduces aGVHD in an IL-10- and Treg-dependent manner, while maintaining immunocompetence and the graft versus leukemia effect.

T cells induce pre-metastatic osteolytic disease and help bone metastases establishment in a mouse model of metastatic breast cancer.

Bone metastases, present in 70% of patients with metastatic breast cancer, lead to skeletal disease, fractures and intense pain, which are all believed to be mediated by tumor cells. Engraftment of tumor cells is supposed to be preceded by changes in the target tissue to create a permissive microenvironment, the pre-metastatic niche, for the establishment of the metastatic foci. In bone metastatic niche, metastatic cells stimulate bone consumption resulting in the release of growth factors that feed the tumor, establishing a vicious cycle between the bone remodeling system and the tumor itself. Yet, how the pre-metastatic niches arise in the bone tissue remains unclear. Here we show that tumor-specific T cells induce osteolytic bone disease before bone colonization. T cells pro-metastatic activity correlate with a pro-osteoclastogenic cytokine profile, including RANKL, a master regulator of osteoclastogenesis. In vivo inhibition of RANKL from tumor-specific T cells completely blocks bone loss and metastasis. Our results unveil an unexpected role for RANKL-derived from T cells in setting the pre-metastatic niche and promoting tumor spread. We believe this information can bring new possibilities for the development of prognostic and therapeutic tools based on modulation of T cell activity for prevention and treatment of bone metastasis.

Efeito protetor da terapia combinada de indução de tolerância oral e tratamento probiótico do doador na Doença Enxerto contra Hospedeiro aguda / [ Protective effect of combined oral tolerance induction therapy and probiotic donor treatment in acute Graft versus Host Disease]

A maior limitação do transplante de células-tronco hematopoiético alogeneico (TCTHa) é a doença enxerto contra hospedeiro (DECH), uma resposta mediada por células T, que está intimamente associada ao efeito benéfico enxerto contra leucemia (ECL). As terapias utilizadas no tratamento da DECH são comumente baseadas na administração de imunossupressores não-específicos, resultando e inúmeras complicações clínicas e inibição do efeito ECL nos pacientes transplantados. Neste trabalho propomos uma abordagem alternativa baseada na indução de tolerância oral com proteínas do receptor em doadores de um transplante semialogeneico, associado à ingestão da bactéria probiótica Lactococcus lactis, utilizada aqui como um adjuvante da tolerância (terapia combinada). O tratamento dos doadores com a terapia combinada previamente ao transplante protegeu os receptores das manifestações clínicas e patológicas da doença, resultando em 100% de sobrevida e ainda foi capaz de manter o efeito enxerto contra leucemia. A proteção é específica, duradoura e dependente da atividade de células B IL-10 suficientes, as quais são capazes de induzir células Treg no receptor. Esses dados sugerem que a terapia combinada representa uma estratégia promissora na prevenção da DECH, mas com a preservação da ECL, abrindo novas possibilidades para o tratamento de pacientes humanos que serão submetidos ao TCTHa. (AU)

The major limitation of allogeneic hematopoietic stem cell transplantation (aHSCT) is graftversus-host disease (GVHD), a T cell-mediated response that is closely related to the benefic graft versus leukemia reaction (GVLr). Therapy for GVHD is commonly based on nonspecific immunosupression of the transplant recipient, resulting in several clinical complications and inhibition of GVLr. Here we propose an alternative approach based on induction of oral tolerance to the recipient antigens in a semiallogenic transplant donors, associated with intake of probiotic Lactococcus lactis as tolerogenic adjuvant (combined therapy). We show that treatment of donor mice with combined therapy before the transplant protects the recipients from clinical and pathological manifestations of disease, resulting in 100% survival rates and maintenance of GVLr. The protection is specific, long lasting and dependent on donor B IL-10 sufficient cells activity, which induces regulatory T cells in the host. These data suggest that combined therapy is a promising strategy for prevention of GVHD with preservation of GVL, opening new possibilities to treat human patients subjected to allogeneic aHSCT. (AU)

Pathogenic effector T cell enrichment overcomes regulatory T cell control and generates autoimmune gastritis.

Regulatory T cells (Treg) deficiency leads to a severe, systemic, and lethal disease, as showed in immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome patients, and scurfy mouse. Postneonatal thymectomy autoimmune gastritis has also been attributed to the absence of Tregs. In this case however, disease is mild, organ-specific, and, more important, it is not an obligatory outcome. We addressed this paradox comparing T cell compartments in gastritis-susceptible and resistant animals. We found that neonatal thymectomy-induced gastritis is not caused by the absence of Tregs. Instead of this, it is the presence of gastritogenic T cell clones that determines susceptibility to disease. The expansion of such clones under lymphopenic conditions results in a reduced Treg:effector T cell ratio that is not enough to control gastritis development. Finally, the presence of gastritogenic clones is determined by the amount of gastric Ag expressed in the neonatal thymus, emphasizing the importance of effector repertoire variability, present even in genetically identical subjects, to organ-specific autoimmune disease susceptibility.