RESUMO
Mast cells (MC) play a central role in the early containment of bacterial infections, such as that caused by Listeria monocytogenes (L.m). The mechanisms of MC activation induced by L.m infection are well known, so it is possible to evaluate whether they are susceptible to targeting and modulation by different drugs. Recent evidence indicates that valproic acid (VPA) inhibits the immune response which favors L.m pathogenesis in vivo. Herein, we examined the immunomodulatory effect of VPA on L.m-mediated MC activation. To this end, bone marrow-derived mast cells (BMMC) were pre-incubated with VPA and then stimulated with L.m. We found that VPA reduced MC degranulation and cytokine release induced by L.m. MC activation during L.m infection relies on Toll-Like Receptor 2 (TLR2) engagement, however VPA treatment did not affect MC TLR2 cell surface expression. Moreover, VPA was able to decrease MC activation by the classic TLR2 ligands, peptidoglycan and lipopeptide Pam3CSK4. VPA also reduced cytokine production in response to Listeriolysin O (LLO), which activates MC by a TLR2-independent mechanism. In addition, VPA decreased the activation of critical events on MC signaling cascades, such as the increase on intracellular Ca2+ and phosphorylation of p38, ERK1/2 and -p65 subunit of NF-κB. Altogether, our data demonstrate that VPA affects key cell signaling events that regulate MC activation following L.m infection. These results indicate that VPA can modulate the functional activity of different immune cells that participate in the control of L.m infection.
Assuntos
Listeria monocytogenes , Listeriose , Citocinas/metabolismo , Humanos , Lipopeptídeos/metabolismo , Listeriose/tratamento farmacológico , Listeriose/metabolismo , Mastócitos/metabolismo , NF-kappa B/metabolismo , Peptidoglicano/metabolismo , Receptor 2 Toll-Like/metabolismo , Ácido Valproico/metabolismo , Ácido Valproico/farmacologiaRESUMO
Valproic acid (VPA) is a drug commonly used for epileptic seizure control. Recently, it has been shown that VPA alters the activation of several immune cells, including Natural Killer (NK) cells, which play an important role in the containment of viruses and intracellular bacteria. Although VPA can increase susceptibility to extracellular pathogens, it is unknown whether the suppressor effect of VPA could affect the course of intracellular bacterial infection. This study aimed to evaluate the role of VPA during Listeria monocytogenes (L.m) infection, and whether NK cell activation was affected. We found that VPA significantly augmented mortality in L.m infected mice. This effect was associated with increased bacterial load in the spleen, liver, and blood. Concurrently, decreased levels of IFN-γ in serum and lower splenic indexes were observed. Moreover, in vitro analysis showed that VPA treatment decreased the frequency of IFN-γ-producing NK cells within L.m infected splenocytes. Similarly, VPA inhibited the production of IFN-γ by NK cells stimulated with IL-12 and IL-18, which is a crucial system for early IFN-γ production in listeriosis. Finally, VPA decreased the phosphorylation of STAT4, p65, and p38, without affecting the expression of IL-12 and IL-18 receptors. Altogether, our results indicate that VPA increases the susceptibility to Listeria monocytogenes infection and suggest that NK cell is one of the main targets of VPA, but further work is needed to ascertain this effect.
Assuntos
Interferon gama/metabolismo , Células Matadoras Naturais/imunologia , Listeria monocytogenes/fisiologia , Listeriose/imunologia , Ácido Valproico/metabolismo , Animais , Células Cultivadas , Modelos Animais de Doenças , Suscetibilidade a Doenças , Feminino , Humanos , Imunomodulação , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos BALB C , Fator de Transcrição STAT4/metabolismo , Transdução de Sinais , Ácido Valproico/imunologiaRESUMO
Mast cell activation through the high-affinity IgE receptor (FcεRI) plays a central role in allergic reactions. FcεRI-mediated activation triggers multiple signaling pathways leading to degranulation and synthesis of different inflammatory mediators. IgE-mediated mast cell activation can be modulated by different molecules, including several drugs. Herein, we investigated the immunomodulatory activity of the histone deacetylase inhibitor valproic acid (VPA) on IgE-mediated mast cell activation. To this end, bone marrow-derived mast cells (BMMC) were sensitized with IgE and treated with VPA followed by FcεRI cross-linking. The results indicated that VPA reduced mast cell IgE-dependent degranulation and cytokine release. VPA also induced a significant reduction in the cell surface expression of FcεRI and CD117, but not other mast cell surface molecules. Interestingly, VPA treatment inhibited the phosphorylation of PLCγ2, a key signaling molecule involved in IgE-mediated degranulation and cytokine secretion. However, VPA did not affect the phosphorylation of other key components of the FcεRI signaling pathway, such as Syk, Akt, ERK1/2, or p38. Altogether, our data demonstrate that VPA affects PLCγ2 phosphorylation, which in turn decreases IgE-mediated mast cell activation. These results suggest that VPA might be a key modulator of allergic reactions and might be a promising therapeutic candidate.
Assuntos
Inibidores de Histona Desacetilases/farmacologia , Imunoglobulina E/imunologia , Mastócitos/efeitos dos fármacos , Fosfolipase C gama/antagonistas & inibidores , Receptores de IgE/efeitos dos fármacos , Ácido Valproico/farmacologia , Animais , Degranulação Celular/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Interleucina-13/metabolismo , Interleucina-6/metabolismo , Mastócitos/citologia , Camundongos , Fosfolipase C gama/fisiologia , Receptores de IgE/biossíntese , Receptores de IgE/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Los receptores para la porción Fc de las inmunoglobulinas G (Fc gamma R) forman parte de la superfamilia de las inmunoglobulinas que se expresan en diferentes tipos celulares y que por su peso molecula, afinidad y especificidad por ligandos, se clasifican en tres grupos (Fc gamma RI, Fc gamma RII y Fc gamma RIII). Además, ciertos polimorfismos genéticos son responsables de la expresión de isoformas que aumentan la heterogeneidad de cada grupo. Los Fc gamma R son tema de intensidad investigación: se conoce la organización de sus genes, propiedades bioquímicas y estructurales. Por otro lado, se sabe que funcionalmente lo Fc gamma R juegan un papel importante en la regulación de la respuesta biológicas generadas durante episodios inflamatorios (infección, por ejemplo), ya que actúan como conectores entre las respuestas inmune celular y humoral. En este artículo presentamos ejemplos donde destaca la participación de los Fc gamma R en funciones de regulación de la respuesta inmune, así como los mecanismos intracelulares que se activan cuando los Fc gamma R son entrecruzados por complejos antígeno-antícuerpo. También recibimos el efecto de citocinas y factores de crecimiento en la regulación de la expresión de los Fc gamma R, remarcando la importancia del posible empleo de éstos en situaciones clínicas en donde las alteraciones de sus niveless de expresión se asocian con ciertos padecimientos y enfermedades. Finalmente, se analiza la participación de los Fc gamma R como vía de entrada para agentes infecciosos tales como el VIH