Differential Roles of Toll-like Receptor (TLR) 2 and 4 between PPD- and 38-kDa-induced Proinflammatory Cytokine Productions in Human Monocytes

In this study, we investigated the role of toll-like receptor (TLR) and mitogen-activated protein kinase (MAPK) pathways involved in the tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 expression after stimulation with purified protein derivatives (PPD) or native 38-kDa protein antigen (Ag) of Mycobacterium tuberculosis H37Rv in human primary monocytes. Both PPD and 38-kDa Ag significantly induced TNF-alpha and IL-6 in human primary monocytes. MAPK [extracellular signal-regulated kinase (ERK) 1/2 and p38] are rapidly phosphorylated in human monocytes stimulated with the PPD or 38-kDa Ag. Both p38 and ERK 1/2 activation are essential for PPD- or 38-kDa-induced TNF-alpha and IL-6 production. The inhibition of TLR2 and TLR4 by specific antibodies significantly abrogated the 38-kDa-induced secretion of TNF-alpha and IL-6, whereas blockade of TLR2, but not TLR4, was responsible for the PPD-induced TNF-alpha and IL-6 production in human monocytes. Collectively, these data suggest that the PPD and 38-kDa Ag differentially interact with TLR2 and TLR4, which in turn mediate an essential role for the early inflammatory immune responses during human tuberculosis.

CD40-CD40 Ligand Interactions in the Production of IL-12 and IFN-gamma by Tuberculous Pleural Mononuclear Cells

BACKGROUND: Our previous study showed that purified protein derivative (PPD)- stimulated pleural mononuclear cells (PMC) from tuberculous pleurisy (Tbp) produced significantly more IFN-gamma (10- to 70-fold) after in vitro PPD stimulation than freshly isolated pleural cells from malignant pleurisy. The present study was designed to determine whether blocking the CD40-CD40 ligand (CD40L) interaction decreases IFN-gamma production by altering IL-12 levels. METHODS: IL-12 and IFN-gamma production after neutralizing anti-CD40L antibody treatment was compared to the efficacy of anti-CD80, anti-CD86, and a combination of anti-CD80 and CD86 (CD80+86) monoclonal antibodies (mAb). These activities were measured by enzyme-linked immunosorbent assays (ELISAs) and reverse transcription-polymerase chain reaction (RT-PCR), after in vitro stimulation with PPD antigen (Ag). RESULTS: Neutralization of CD80, CD86 and CD80+86 did not decrease IFN-gamma and IL-12 production in Tbp-PMC, whereas neutralization of CD40L significantly depressed IL-12 p40 and IFN-gamma. In addition, neutralization of CD40L completely inhibited IL-12 p40 and IFN-gamma mRNA expression. CONCLUSION: The CD40-CD40L interaction might play a major role in IL-12 and IFN-gamma production in Tbp-PMC, thus contributing to protective immunity in human tuberculosis.

CD40-CD40 Ligand Interactions in the Production of IL-12 and IFN-gamma by Tuberculous Pleural Mononuclear Cells

BACKGROUND: Our previous study showed that purified protein derivative (PPD)- stimulated pleural mononuclear cells (PMC) from tuberculous pleurisy (Tbp) produced significantly more IFN-gamma (10- to 70-fold) after in vitro PPD stimulation than freshly isolated pleural cells from malignant pleurisy. The present study was designed to determine whether blocking the CD40-CD40 ligand (CD40L) interaction decreases IFN-gamma production by altering IL-12 levels. METHODS: IL-12 and IFN-gamma production after neutralizing anti-CD40L antibody treatment was compared to the efficacy of anti-CD80, anti-CD86, and a combination of anti-CD80 and CD86 (CD80+86) monoclonal antibodies (mAb). These activities were measured by enzyme-linked immunosorbent assays (ELISAs) and reverse transcription-polymerase chain reaction (RT-PCR), after in vitro stimulation with PPD antigen (Ag). RESULTS: Neutralization of CD80, CD86 and CD80+86 did not decrease IFN-gamma and IL-12 production in Tbp-PMC, whereas neutralization of CD40L significantly depressed IL-12 p40 and IFN-gamma. In addition, neutralization of CD40L completely inhibited IL-12 p40 and IFN-gamma mRNA expression. CONCLUSION: The CD40-CD40L interaction might play a major role in IL-12 and IFN-gamma production in Tbp-PMC, thus contributing to protective immunity in human tuberculosis.