RESUMO
Naive T cells are known to express the modest level of TLR4 while it is known to go down during TCR activation. However, information towards the requirement of TLR4 signaling during TCR or mitogenic activation of naive wild-type T cells remains scanty. Here we have investigated the endogenous functional expression of TLR4 in naive mice T cells during TCR and mitogenic stimulation in presence of VIPER peptide (VP), an established inhibitor of TLR4 signaling. As expected we found that TLR4 expression goes down during TCR and mitogenic activation. Interestingly, we observed that VP treatment restores TLR4 expression on those activated T cells. Moreover, VP was found to regulate such activation of naive T cell as evident by reduction of CD25, CD69 expression, effector cytokines (IL-2, IFN-γ, TNF) production, T cell proliferation and down-regulation of T cell activation-dependent Fas (CD95), FasL (CD95L) expression. Together, our current observation highlights a possible requirement of TLR4 responses in T cells, which might have possible implication towards the pathogenic acute phase activation of naive T cells.
Assuntos
Proliferação de Células/genética , Linfócitos T/efeitos dos fármacos , Receptor 4 Toll-Like/genética , Proteínas Virais/farmacologia , Animais , Antígenos CD/genética , Antígenos de Diferenciação de Linfócitos T/genética , Proliferação de Células/efeitos dos fármacos , Citocinas/efeitos dos fármacos , Citocinas/genética , Proteína Ligante Fas/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Subunidade alfa de Receptor de Interleucina-2/genética , Lectinas Tipo C/genética , Camundongos , Transdução de Sinais/efeitos dos fármacos , Linfócitos T/metabolismo , Receptor 4 Toll-Like/antagonistas & inibidores , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/efeitos dos fármacos , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/genética , Proteínas Virais/químicaRESUMO
The importance of Ca(2+) signalling and temperature in the context of T cell activation is well known. However, the molecular identities of key players involved in such critical regulations are still unknown. In this work we explored the endogenous expression of transient receptor potential vanilloid (TRPV) channels, a group of thermosensitive and non-selective cation channels, in T cells. Using flow cytometry and confocal microscopy, we demonstrate that members belonging to the TRPV subfamily are expressed endogenously in the human T cell line Jurkat, in primary human T cells and in primary murine splenic T cells. We also demonstrate that TRPV1- and TRPV4-specific agonists, namely resiniferatoxin and 4α-phorbol-12,13-didecanoate, can cause Ca(2+) influx in T cells. Moreover, our results show that expression of these channels can be upregulated in T cells during concanavalin A-driven mitogenic and anti-CD3/CD28 stimulated TCR activation of T cells. By specific blocking of TRPV1 and TRPV4 channels, we found that these TRPV inhibitors may regulate mitogenic and T cell receptor mediated T cell activation and effector cytokine(s) production by suppressing tumour necrosis factor, interleukin-2 and interferon-γ release. These results may have broad implications in the context of cell-mediated immunity, especially T cell responses and their regulations, neuro-immune interactions and molecular understanding of channelopathies.