RESUMO
Serum IgG, which is mainly generated from IgG-secreting plasma cells in the bone marrow (BM), protects our body against various pathogens. We show here that the protein SiiE of Salmonella is both required and sufficient to prevent an efficient humoral immune memory against the pathogen by selectively reducing the number of IgG-secreting plasma cells in the BM. Attenuated SiiE-deficient Salmonella induces high and lasting titers of specific and protective Salmonella-specific IgG and qualifies as an efficient vaccine against Salmonella A SiiE-derived peptide with homology to laminin ß1 is sufficient to ablate IgG-secreting plasma cells from the BM, identifying laminin ß1 as a component of niches for IgG-secreting plasma cells in the BM, and furthermore, qualifies it as a unique therapeutic option to selectively ablate IgG-secreting plasma cells in autoimmune diseases and multiple myeloma.
Assuntos
Células da Medula Óssea/imunologia , Imunidade Humoral , Imunoglobulina G/imunologia , Memória Imunológica , Plasmócitos/imunologia , Salmonella/imunologia , Animais , Células da Medula Óssea/citologia , Imunoglobulina G/genética , Laminina/genética , Laminina/imunologia , Camundongos , Camundongos Knockout , Plasmócitos/citologia , Salmonella/genéticaRESUMO
Hypoxia driven angiogenesis is a prominent feature of tissue regeneration, inflammation and tumor growth and is regulated by hypoxia-inducible factor (HIF)-1 and -2. The distinct functions of HIFs in the hypoxia-induced angiogenesis and metabolic switch of endothelial cells are still unknown and therefore aim of this study. We investigated the role of HIF-1 and -2 in the adaptation of immortalized human microvascular endothelial cells (HMEC-1) to hypoxic conditions (1% O2) in terms of angiogenesis, cytokine secretion, gene expression and ATP/ADP-ratio using shRNA-mediated reduction of the oxygen sensitive α-subunits of either HIF-1 or HIF-2 or the combination of both. Reduction of HIF-1α diminished cellular energy, hypoxia-induced glycolytic gene expression, and angiogenesis not altering pro-angiogenic factors. Reduction of HIF-2α diminished hypoxia-induced pro-angiogenic factors, enhanced anti-angiogenic factors and attenuated angiogenesis not altering glycolytic gene expression. Reduction of both HIFs reduced cell survival, gene expression of glycolytic enzymes and pro-angiogenic factors as compared to the corresponding control. Finally, we identified the macrophage migration inhibitory factor (MIF) to be redundantly regulated by HIF-1 and HIF-2 and to be essential in the process of hypoxia-driven angiogenesis. Our results demonstrate a major impact of HIF-1 and HIF-2 on hypoxia-induced angiogenesis indicating distinct but also overlapping functions of HIF-1 and HIF-2. These findings open new possibilities for therapeutic approaches by specifically targeting the HIF-1 and HIF-2 or their target MIF.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Células Endoteliais/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Oxirredutases Intramoleculares/metabolismo , Fatores Inibidores da Migração de Macrófagos/metabolismo , Microvasos/metabolismo , Neovascularização Fisiológica , Adaptação Fisiológica , Antígenos de Diferenciação de Linfócitos B/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Hipóxia Celular , Linhagem Celular , Microambiente Celular , Regulação Enzimológica da Expressão Gênica , Glicólise , Antígenos de Histocompatibilidade Classe II/metabolismo , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Oxirredutases Intramoleculares/genética , Fatores Inibidores da Migração de Macrófagos/genética , Microvasos/citologia , Neovascularização Fisiológica/genética , Transdução de SinaisRESUMO
Mobilizable genomic islands (MGIs) are small genomic islands that are mobilizable by SXT/R391 integrating conjugative elements (ICEs) due to similar origins of transfer. Their site-specific integration and excision are catalyzed by the integrase that they encode, but their conjugative transfer entirely depends upon the conjugative machinery of SXT/R391 ICEs. In this study, we report the mechanisms that control the excision and integration processes of MGIs. We found that while the MGI-encoded integrase Int(MGI) is sufficient to promote MGI integration, efficient excision from the host chromosome requires the combined action of Int(MGI) and of a novel recombination directionality factor, RdfM. We determined that the genes encoding these proteins are activated by SetCD, the main transcriptional activators of SXT/R391 ICEs. Although they share the same regulators, we found that unlike rdfM, int(MGI) has a basal level of expression in the absence of SetCD. These findings explain how an MGI can integrate into the chromosome of a new host in the absence of a coresident ICE and shed new light on the cross talk that can occur between mobilizable and mobilizing elements that mobilize them, helping us to understand part of the rules that dictate horizontal transfer mechanisms.
Assuntos
Ilhas Genômicas , Bactérias Gram-Negativas/genética , Sequências Repetitivas Dispersas , Recombinases/biossíntese , Recombinação Genética , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Dados de Sequência Molecular , Alinhamento de SequênciaRESUMO
CD4 T cell memory is fundamental for long-lasting immunity and effective secondary responses following infection or vaccination. We have previously found that memory CD4 T cells specific for systemic antigens preferentially reside in the bone marrow (BM) and arise from splenic CD49b+T-bet+ CD4 T cells. However, how BM-homing memory precursors are generated during an immune reaction is unknown. We show here that BM memory precursors are generated via augmented rates of cell division throughout a primary immune response. Treatment with the cytostatic drug cyclophosphamide or blockade of the CD28/B7 co-stimulatory pathway at the beginning of the contraction phase abrogates the generation of BM memory precursors. We determine that, following a critical number of cell divisions, memory precursors downregulate CCR7 and upregulate IL-2Rß, indicating that loss of CCR7 and gain of IL-2 signal are required for the migration of memory precursors toward the BM.
Assuntos
Medula Óssea/imunologia , Linfócitos T CD4-Positivos/imunologia , Divisão Celular/imunologia , Movimento Celular/imunologia , Memória Imunológica , Animais , Antígenos CD28/genética , Antígenos CD28/imunologia , Linfócitos T CD4-Positivos/citologia , Divisão Celular/genética , Integrina alfa2/genética , Integrina alfa2/imunologia , Interleucina-2/genética , Interleucina-2/imunologia , Subunidade beta de Receptor de Interleucina-2/genética , Subunidade beta de Receptor de Interleucina-2/imunologia , Camundongos , Camundongos Knockout , Receptores CCR7/genética , Receptores CCR7/imunologia , Proteínas com Domínio T/genética , Proteínas com Domínio T/imunologiaRESUMO
During an immune reaction, some antigen-experienced CD4 T cells relocate from secondary lymphoid organs (SLOs) to the bone marrow (BM) in a CD49b-dependent manner and reside and rest there as professional memory CD4 T cells. However, it remains unclear how the precursors of BM memory CD4 T cells are generated in the SLOs. While several studies have so far shown that B cell depletion reduces the persistence of memory CD4 T cells in the spleen, we here show that B cell depletion enhances the establishment of memory CD4 T cells in the BM and that B cell transfer conversely suppresses it. Interestingly, the number of antigen-experienced CD4 T cells in the BM synchronizes the number of CD49b(+)T-bet(+) antigen-experienced CD4 T cells in the spleen. CD49b(+)T-bet(+) antigen-experienced CD4 T cells preferentially localize in the red pulp area of the spleen and the BM in a T-bet-independent manner. We suggest that B cells negatively control the generation of CD49b(+)T-bet(+) precursors of resting memory CD4 T cells in the spleen and may play a role in bifurcation of activated effector and resting memory CD4 T cell lineages.