Neurocysticercosis, infection with larval Taenia solium, is a common, serious neuroparasitic infection. Larval degeneration results in inflammatory cell influx and granuloma formation which leads to clinical symptomatology. The role of chemokines in such cell influx is unknown. We demonstrate that monocyte stimulation by T. solium larval antigen (TsAg) results in a differential profile of CXCL8/IL-8 (146.5 ± 8.5 ng/ml after 24 h), CCL2/MCP-1 (267 ± 4 ng/ml after 48 h) and CCL3/MIP-1α (1.72 ± 0.43 ng/ml after 8 h) secretion. There was coordinate mRNA accumulation reaching maximum at 1 h for CCL3 and 2 h for CXCL8 and CCL2. TsAg induced maximal nuclear binding of p65, p50 and c-rel subunits of the transcriptional regulator NF-κB by 2 h. IκBα but not IκBβ was degraded within 10 min before resynthesis by 2 h. Pre-treatment with the broad-spectrum NF-κB inhibitor pyrrolidine dithiocarbamate caused complete abrogation of TsAg-induced CCL2 secretion (p = 0.005) and 91% reduction of CXCL8 secretion (p = 0.0003). TsAg was unable to induce CXCL8 promoter activity in Toll-like receptor (TLR)-2 or TLR-4/MD-2 transfected HeLa cells in the absence of lectins or other adaptor molecules. In summary, our data demonstrate that TsAg induces chemokine secretion via specific pathways dependent on NF-κB but not TLR-4/TLR-2, and indicate a potential mechanism whereby larval degeneration results in brain inflammation.
Bibliographical noteFunding Information:
We thank Dr. José A. Chabalgoity for critical reading and helpful comments. This work was supported by grant numbers AI-42037-01 and AI-35894 from the National Institutes of Health, USA, the ITREID training grant TW00910 and by The Wellcome Trust.
- Toll-like receptor