RESUMO
Angiotensin II (Ang II) and its receptor AT1 (AT1R), an important effector axis of renin-angiotensin system (RAS), have been demonstrated to regulate T-cell responses. However, these studies characterized Ang II and AT1R effects using pharmacological tools, which do not target only Ang II/AT1R axis. The specific role of AT1R expressed by antigen-specific CD8+ T cells is unknown. Then we immunized transgenic mice expressing a T-cell receptor specific for SIINFEKL epitope (OT-I mice) with sporozoites of the rodent malaria parasite Plasmodium berghei expressing the cytotoxic epitope SIINFEKL. Early priming events after immunization were not affected but the expansion and contraction of AT1R-deficient (AT1R-/-) OT-I cells was decreased. Moreover, they seemed more activated, express higher levels of CTLA-4, PD-1, LAG-3, and have decreased functional capacity during the effector phase. Memory AT1R-/- OT-I cells exhibited higher IL-7Rα expression, activation, and exhaustion phenotypes but less cytotoxic capacity. Importantly, AT1R-/- OT-I cells show better control of blood parasitemia burden and ameliorate mice survival during lethal disease induced by blood-stage malaria. Our study reveals that AT1R in antigen-specific CD8+ T cells regulates expansion, differentiation, and function during effector and memory phases of the response against Plasmodium, which could apply to different infectious agents.
Assuntos
Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Receptor Tipo 1 de Angiotensina/imunologia , Animais , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular , Citotoxicidade Imunológica , Imunização , Epitopos Imunodominantes/genética , Memória Imunológica , Ativação Linfocitária , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Ovalbumina/imunologia , Fragmentos de Peptídeos/imunologia , Plasmodium berghei/imunologia , Plasmodium berghei/patogenicidade , Receptor Tipo 1 de Angiotensina/deficiência , Receptor Tipo 1 de Angiotensina/genética , Esporozoítos/imunologia , Esporozoítos/patogenicidadeRESUMO
Dendritic cells (DC) are highly specialized antigen-presenting cells with a unique ability to activate resting T lymphocytes and initiate primary immune responses. Angiotensin II (AII) is involved in key events of the inflammatory response. Because our previous work implicated an effect of AII on differentiation and function of murine and human DC, we investigated the impact of AII type 1 receptor (AT(1)) deficiency on the phenotypical and functional properties of mouse DC in vitro and in vivo. Bone marrow (BM) cells isolated from mice lacking AII subtype 1a receptor (AT(1a)), AII subtype 1b receptor (AT(1b)), or both receptor isoforms and control littermates [wild type (WT)] were cultured for 7 days in the presence of recombinant mouse granulocyte/macrophage colony-stimulating factor to generate myeloid DC in vitro. Generation of CD11c(+) cells was less efficient in both AT(1a)- and AT(1b)-deficient BM cells than in WT BM cell cultures. Moreover, DC generated from AT(1)-deficient progenitors showed lower levels of expression of major histocompatibility complex II (MHC-II) and CD11c (p < 0.01) and a marked reduction in their allostimulatory activity (p < 0.01 or 0.001). Although AT(1)-deficient DC released comparable levels of interleukin (IL)-10 and IL-12p70 to WT DC, they produced significantly lower levels of tumor necrosis factor alpha (TNF-alpha) (p < 0.05). Remarkably, CD11c(+) cells isolated from the spleen of AT(1) knockout mice challenged with lipopolysaccharide in vivo up-regulated MHC-II, CD40, and CD80 as did WT, but released significantly lower levels of TNF-alpha (p < 0.01). These data provide clear evidence that AT(1) controls differentiation and functionality of DC and thus may have a crucial impact on inflammatory processes where local angiotensinergic systems are known to be activated.
Assuntos
Células Dendríticas/fisiologia , Receptor Tipo 1 de Angiotensina/genética , Animais , Western Blotting , Antígeno CD11c/metabolismo , Separação Celular , Citocinas/metabolismo , Células Dendríticas/ultraestrutura , Endocitose , Citometria de Fluxo , Genes MHC da Classe II/genética , Genótipo , Lipopolissacarídeos/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor Tipo 1 de Angiotensina/deficiência , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Baço/citologia , Linfócitos T/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacosRESUMO
Experiments were performed to study the physiological regulation of angiotensin (Ang) AT1b receptors using Ang AT1a knockout mice (AT1aKO). Ang AT1b mRNA was analyzed in forebrain, hypothalamus, and brainstem using in situ hybridization (ISH) under baseline and water-restricted conditions. Plasma was analyzed for osmolality, vasopressin, and corticosterone. Dehydration (24 h) increased osmolality and corticosterone and decreased body weight with no difference between groups. Plasma vasopressin was not different between the groups and was not stimulated by dehydration. Under water ad libitum conditions, there were no differences in AT1b mRNA expression in medial periventricular, anterior third ventricle (AV3V), and subfornical organ (SFO) between controls and AT1aKO. In contrast, there was higher expression in the dorsal motor nucleus of the vagus (DMV) of AT1aKO vs. Controls (0.6 +/- 0.1 vs. 0.9 +/- 0.1 microCi/g, Control vs. AT1aKO in water ad libitum group). Dehydration increased AT1b expression in SFO in AT1aKO, but not in controls (0.6 +/- 0.07 vs. 0.9 +/- 0.06 microCi/g; water ad libitum vs. dehydrated). Emulsion autoradiography documents the detailed pattern of AT1b expression in brainstem of controls and AT1aKO. There was labeling in DMV, locus coeruleus, inferior olive, lateral reticular nucleus, and caudalis spinal trigemius. In conclusion, deletion of AT1a receptors produces a compensatory increase in AT1b receptor mRNA expression in brainstem, but not in hypothalamus or rostral forebrain. In addition, AT1aKO mice showed an enhanced response to dehydration in terms of AT1b mRNA expression in SFO.