RESUMO
Interleukin-2 (IL-2) is a critical regulator of immune homeostasis through its non-redundant role in regulatory T (Treg) cell biology. There is major interest in therapeutic modulation of the IL-2 pathway to promote immune activation in the context of tumour immunotherapy or to enhance immune suppression in the context of transplantation, autoimmunity and inflammatory diseases. Antibody-mediated targeting of the high-affinity IL-2 receptor α chain (IL-2Rα or CD25) offers a direct mechanism to target IL-2 biology and is being actively explored in the clinic. In mouse models, the rat anti-mouse CD25 clone PC61 has been used extensively to investigate the biology of IL-2 and Treg cells; however, there has been controversy and conflicting data on the exact in vivo mechanistic function of PC61. Engineering antibodies to alter Fc/Fc receptor interactions can significantly alter their in vivo function. In this study, we re-engineered the heavy chain constant region of an anti-CD25 monoclonal antibody to generate variants with highly divergent Fc effector function. Using these anti-CD25 Fc variants in multiple mouse models, we investigated the in vivo impact of CD25 blockade versus depletion of CD25(+) Treg cells on immune homeostasis. We report that immune homeostasis can be maintained during CD25 blockade but aberrant T-cell activation prevails when CD25(+) Treg cells are actively depleted. These results clarify the impact of PC61 on Treg cell biology and reveal an important distinction between CD25 blockade and depletion of CD25(+) Treg cells. These findings should inform therapeutic manipulation of the IL-2 pathway by targeting the high-affinity IL-2R.
Assuntos
Anticorpos Monoclonais/farmacologia , Imunoglobulina G/farmacologia , Imunoterapia , Interleucina-2/metabolismo , Proteínas Recombinantes de Fusão/farmacologia , Linfócitos T Reguladores/efeitos dos fármacos , Animais , Anticorpos Monoclonais/genética , Anticorpos Antivirais/imunologia , Autoimunidade/imunologia , Fatores de Transcrição Forkhead/metabolismo , Homeostase/efeitos dos fármacos , Imunoglobulina G/genética , Terapia de Imunossupressão , Interleucina-2/imunologia , Depleção Linfocítica , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Engenharia de Proteínas , Ratos , Receptores de IgG/genética , Proteínas Recombinantes de Fusão/genética , Linfócitos T Reguladores/imunologiaRESUMO
Fumarate-containing pharmaceuticals are potent therapeutic agents that influence multiple cellular pathways. Despite proven clinical efficacy, there is a significant lack of data that directly defines the molecular mechanisms of action of related, yet distinct fumarate compounds. We systematically compared the impact of dimethyl fumarate (DMF), monomethyl fumarate (MMF) and a mixture of monoethyl fumarate salts (Ca(++), Mg(++), Zn(++); MEF) on defined cellular responses. We demonstrate that DMF inhibited NF-κB-driven cytokine production and nuclear translocation of p65 and p52 in an Nrf2-independent manner. Equivalent doses of MMF and MEF did not affect NF-κB signaling. These results highlight a key difference in the biological impact of related, yet distinct fumarate compounds.
Assuntos
Fumaratos/farmacologia , NF-kappa B/antagonistas & inibidores , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Animais , Neoplasias Ósseas/patologia , Linfoma de Burkitt/patologia , Cátions/farmacologia , Linhagem Celular Tumoral , Células Cultivadas , Citocinas/metabolismo , Fumarato de Dimetilo , Humanos , Técnicas In Vitro , Linfócitos/efeitos dos fármacos , Linfócitos/metabolismo , Maleatos/farmacologia , Camundongos , Camundongos Knockout , Estrutura Molecular , Fator 2 Relacionado a NF-E2/deficiência , Fator 2 Relacionado a NF-E2/fisiologia , Subunidade p52 de NF-kappa B/metabolismo , Proteínas de Neoplasias/antagonistas & inibidores , Osteossarcoma/patologia , Transdução de Sinais/efeitos dos fármacos , Baço/citologia , Fator de Transcrição RelA/metabolismoRESUMO
The chemokine CXCL12 and its receptor CXCR4 are expressed widely in human cancers, including ovarian cancer, in which they are associated with disease progression at the levels of tumor cell proliferation, invasion, and angiogenesis. Here, we used an immunocompetent mouse model of intraperitoneal papillary epithelial ovarian cancer to show that modulation of the CXCL12/CXCR4 axis in ovarian cancer has multimodal effects on tumor pathogenesis associated with induction of antitumor immunity. siRNA-mediated knockdown of CXCL12 in BR5-1 cells that constitutively express CXCL12 and CXCR4 reduced cell proliferation in vitro, and tumor growth in vivo. Similarly, treatment of BR5-1-derived tumors with AMD3100, a selective CXCR4 antagonist, resulted in increased tumor apoptosis and necrosis, reduction in intraperitoneal dissemination, and selective reduction of intratumoral FoxP3(+) regulatory T cells (Treg). Compared with controls, CXCR4 blockade greatly increased T-cell-mediated antitumor immune responses, conferring a significant survival advantage to AMD3100-treated mice. In addition, the selective effect of CXCR4 antagonism on intratumoral Tregs was associated with both higher CXCR4 expression and increased chemotactic responses to CXCL12, a finding that was also confirmed in a melanoma model. Together, our findings reinforce the concept of a critical role for the CXCL12/CXCR4 axis in ovarian cancer pathogenesis, and they offer a definitive preclinical validation of CXCR4 as a therapeutic target in this disease.