Mycobacterium bovis Bacillus Calmette-Guérin (BCG) INDUCES CCL5 SECRETION VIA THE TOLL-LIKE RECEPTOR 2-NF-kappaB AND -JNK SIGNALING PATHWAYS

Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, IPN, Carpio y Plan de Ayala, México, D.F. 11340 México

^* To whom correspondence should be addressed. Email: pmendezs{at}bios.encb.ipn.mx.

	Abstract

In response to Mycobacterium bovis bacillus Calmette-Guérin (BCG), CC-chemokines are secreted from host cells to attract components of the innate and adaptive immune systems to the site of infection. Toll-like receptor 2 (TLR2) has been shown to recognize M.bovis BCG and to initiate signaling pathways that result in enhanced secretion of CC-chemokines. Despite the essential requirement of TLR2 in M.bovis BCG infection, the mechanisms by which it induces CC-chemokines secretion are not well defined. In this study, we report that stimulation with M.bovis BCG of HEK293 cells expressing human TLR2 resulted in increased CCL2 and CCL5 secretion as determined by ELISA. M.bovis BCG infection resulted in the activation of c-Jun N-terminal kinase (JNK), and the inhibition of JNK activity had significant effect on M.bovis BCG-dependent CCL5 secretion in TLR2-expressing cells, whereas inhibition of JNK had no effect on M.bovis BCG-dependent CCL2 secretion from infected HEK293 cells expressing human TLR2. The M.bovis BCG-induced CCL5 release was attenuated by sulfasalazine (a well-described inhibitor of NF-kB activity), BAY 11-7082 (an IkB phosphorylation inhibitor), and ALLN (a well-described inhibitor of NF-kB activation which prevents degradation of IkB and eventually results in a lack of translocated NF-kB in the nucleus). In addition, stimulation of TLR2 cells with M.bovis BCG resulted in translocation of NF-kB subunits from the cytoplasmic to the nuclear fraction, and stimulation of cells with M.bovis BCG activated IkB kinase (IKK). These findings indicate that M.bovis BCG induces CCL5 production through mechanisms that include a TLR2-dependent component that requires JNK and NF-kB activity.