Activation of Phosphatidylinositol 3-Kinase/Akt and Impairment of Nuclear Factor-κB:Molecular Mechanisms Behind the Arrested Maturation/Activation State of Leishmania infantum-Infected Dendritic Cells

• Type: Article in International Scientific Journal
• Date: 2010

Authors

Bruno Miguel Neves (Author) Other; Ricardo Silvestre (Author) Other; Mariana Resende (Author) Other; Ali Ouaissi (Author) Other; Joana Cunha (Author) Other; Joana Tavares (Author) Other; Ineês Loureiro (Author) Other; Nuno Santarém (Author) Other; Ana Marta Silva (Author) Other; Maria Celeste Lopes (Author) Other; Maria Teresa Cruz (Author) Other; Anabela Cordeiro da Silva (Author) FFUP

Journal

Title: The American Journal of Pathology

Vol. 177 No. 6

Pages: 2898-2911

ISSN: 0002-9440

Publisher: AMER SOC INVESTIGATIVE PATHOLOGY, INC

Indexing

Scopus

Pubmed / Medline

Scientific classification

FOS: Medical and Health sciences > Health sciences

CORDIS: Physical sciences > Chemistry > Biochemistry

Other information

Resumo (PT): Understanding the complex interactions between Leishmania and dendritic cells (DCs) is central to the modulation of the outcome of this infection, given that an effective immune response against Leishmania is dependent on the successful activation and maturation of DCs. We report here that Leishmania infantum promastigotes successfully infect mouse bone marrow-derived DCs without triggering maturation, as shown by a failure in the up-regulation of CD40 and CD86 expression, and that parasites strongly counteract the lipopolysaccharide-triggered maturation of DCs. A small increase in interleukin (IL)-12 and IL-10 transcription and secretion and a decrease in IL-6 were observed in infected cells. This arrested DC maturation state is actively promoted by parasites because heat-killed or fixed parasites increased cytokine and costimulatory molecule expression. At a molecular level, L. infantum rapidly induced activation of phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase 1/2, whereas no effect was observed in the c-Jun N-terminal kinase and p38 mitogen-activated protein kinase proinflammatory pathways. Moreover, parasites actively promoted cleavage of the nuclear factor-κB p65RelA subunit, causing its impairment. The blockade of phosphatidylinositol 3-kinase/Akt by either treatment of bone marrow-derived DCs with wortmannin or transfection with an Akt dominant-negative mutant resulted in a strong decrease in infection rates, revealing for the first time a crucial role of this pathway on Leishmania engulfment by DCs. Overall, our data indicate that activation of Akt and impairment of nuclear factor-κB are responsible for immunogenicity subversion of L. infantum-infected DCs. <br> <br> <a target="_blank" href="http://www.journals.elsevierhealth.com/periodicals/ajpa/article/S0002-9440(10)62917-3/abstract">Texto integral</a>

Abstract (EN): Understanding the complex interactions between Leishmania and dendritic cells (DCs) is central to the modulation of the outcome of this infection, given that an effective immune response against Leishmania is dependent on the successful activation and maturation of DCs. We report here that Leishmania infantum promastigotes successfully infect mouse bone marrow-derived DCs without triggering maturation, as shown by a failure in the up-regulation of CD40 and CD86 expression, and that parasites strongly counteract the lipopolysaccharide-triggered maturation of DCs. A small increase in interleukin (IL)-12 and IL-10 transcription and secretion and a decrease in IL-6 were observed in infected cells. This arrested DC maturation state is actively promoted by parasites because heat-killed or fixed parasites increased cytokine and costimulatory molecule expression. At a molecular level, L. infantum rapidly induced activation of phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase 1/2, whereas no effect was observed in the c-Jun N-terminal kinase and p38 mitogen-activated protein kinase proinflammatory pathways. Moreover, parasites actively promoted cleavage of the nuclear factor-κB p65RelA subunit, causing its impairment. The blockade of phosphatidylinositol 3-kinase/Akt by either treatment of bone marrow-derived DCs with wortmannin or transfection with an Akt dominant-negative mutant resulted in a strong decrease in infection rates, revealing for the first time a crucial role of this pathway on Leishmania engulfment by DCs. Overall, our data indicate that activation of Akt and impairment of nuclear factor-κB are responsible for immunogenicity subversion of L. infantum-infected DCs. <br> <br> <a target="_blank" href="http://www.journals.elsevierhealth.com/periodicals/ajpa/article/S0002-9440(10)62917-3/abstract"> um Full text</a>

Language: English

Type (Professor's evaluation): Scientific