Murine Dendritic Cells Transcriptional Modulation upon Paracoccidioides brasiliensis Infection

Abstract

Limited information is available regarding the modulation of genes involved in the innate host response to Paracoccidioides brasiliensis, the etiologic agent of paracoccidioidomycosis. Therefore, we sought to characterize, for the first time, the transcriptional profile of murine bone marrow-derived dendritic cells (DCs) at an early stage following their initial interaction with P. brasiliensis. DCs connect innate and adaptive immunity by recognizing invading pathogens and determining the type of effector T-cell that mediates an immune response. Gene expression profiles were analyzed using microarray and validated using real-time RT-PCR and protein secretion studies. A total of 299 genes were differentially expressed, many of which are involved in immunity, signal transduction, transcription and apoptosis. Genes encoding the cytokines IL-12 and TNF-α, along with the chemokines CCL22, CCL27 and CXCL10, were up-regulated, suggesting that P. brasiliensis induces a potent proinflammatory response in DCs. In contrast, pattern recognition receptor (PRR)-encoding genes, particularly those related to Toll-like receptors, were down-regulated or unchanged. This result prompted us to evaluate the expression profiles of dectin-1 and mannose receptor, two other important fungal PRRs that were not included in the microarray target cDNA sequences. Unlike the mannose receptor, the dectin-1 receptor gene was significantly induced, suggesting that this β-glucan receptor participates in the recognition of P. brasiliensis. We also used a receptor inhibition assay to evaluate the roles of these receptors in coordinating the expression of several immune-related genes in DCs upon fungal exposure. Altogether, our results provide an initial characterization of early host responses to P. brasiliensis and a basis for better understanding the infectious process of this important neglected pathogen.

Dendritic cell interactions withHistoplasmaandParacoccidioides

“…90,95 IL-12 produced by DCs seems to be the key cytokine that stimulates a preferential, inflammatory Th1 type immune response, which is an important defense in systemic fungal infections. 96 DCs are part of the first line of defense against P. brasiliensis infection and the migration of DCs to the lymph nodes is a key initial step toward the induction of a T cell response. 15,90 Silvana et al observed an increased expression of CCR7, CD103 and MHC II on the surface of lung DCs after infection with P. brasiliensis, which enables migration to lymph nodes where T cell activation takes place and initiates a predominant T helper response.…”

“…112 Supporting these results, Tavares et al recently utilized microarrays to determine the expression of DC genes involved in immunity and found that genes encoding cytokines IL-12 and TNF-a, along with the chemokines CCL -22, CCL -27 and CXCL -10, were up-regulated, suggesting that P. brasiliensis induces the production of cytokines and chemokines as well as other molecules that participate in the early response of DCs to this fungus. 96 …”

Caracterização das bases moleculares da resposta imune inata do hospedeiro murino à paracoccidiomicose

“…Entretanto, apesar da importância de identificação de novos alvos terapêuticos, até o presente momento somente três estudos focaram na descrição do padrão de expressão de genes relacionados ao sistema imune inato do hospedeiro quando o mesmo foi submetido à infecção ex vivo por P. brasiliensis , Oliveira et al 2010, Tavares et al 2012. Tais estudos investigaram a resposta: de células dendríticas murinas -sentinelas e principal orquestradora do sistema imune (Tavares et al 2012), de pneumócitos do tipo II humanos imortalizadas -também sentinelas e moduladoras do sistema imune (Oliveira et al 2010) e de macrófagos peritoneais murinos -sentinelas, moduladoras e células efetoras do sistema imune ) frente à infecção por P. brasiliensis, sugerindo a importância de alguns genes durante a interação dessas células hospedeiras com o fungo.…”

“…CARD9: caspase recruitment domain-containing protein 9; CCL3: CC-chemokine ligand 3; CR3: complement receptor 3; DC-SIGN: DC-specific ICAM3-grabbing non-integrin; FcRγ: Fc receptor γ-chain; GXMR: receptor(s) for the Cryptococcus capsular component glucuronoxylomannan; IDO: indoleamine 2,3-dioxygenase; IFN: interferon; IL: interleukin; IRF3: IFNregulatory factor 3; MR: mannose receptor; MYD88: myeloid differentiation primary response protein 88; NF-κB: nuclear factor-κB; SYK: spleen tyrosine kinase; TGFβ: transforming growth fator-β; TLR: Toll-like receptor; TRIF: TIR domain-containing adaptor protein inducing IFNβ (também conhecido como TICAM1); VLA5: very late antigen 5. Tavares et al (2012), com uso de "microarray", demonstraram que 299 genes foram diferencialmente expressos em DCs (Balb/c) infectadas por P. brasiliensis. Esta informação genética estava envolvida na imunidade, transdução de sinal, transcrição e apoptose.…”

“…Esta informação genética estava envolvida na imunidade, transdução de sinal, transcrição e apoptose. Dentre essas vias, os genes que codificam para citocinas IL-12 e TNF-α, juntamente com quimiocinas CCL-22, CCL-27 e CXCL-10, foram induzidos na infecção por P. brasiliensis, bem como outras moléculas que participam na resposta precoce, o que sugere uma forte resposta proinflamatória em DCs para este fungo (Tavares et al 2012). Em contraste, os genes relacionados com PRR, em particular TLRs, encontram-se reprimidos ou não modulados (Tavares et al 2012).…”