Novel Roles of Osteopontin and CXC Chemokine Ligand 7 in the Defense against Mycobacterial Infection

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced human monocyte-derived macrophage (GM-Mphage) or macrophage CSF (M-CSF)-induced human monocyte-derived Mphage (M-Mphage) are distinct in terms of the resistance to Mycobacterium tuberculosis (M. tuberculosis). To elucidate the role of molecules involved in the functional differences between these Mphages, we investigated the gene expression profiles using microarray. After culture of CD14+ monocytes with CSFs, Mphages were cultured with or without BCG (GM-Mf-BCG and M-Mf-BCG). The gene expression profiles from these cells were compared. Chemokines highly expressed in M-Mphages were selected and evaluated for antimycobacterial activity and superoxide production. FN1 and FCGR2B were the most up-regulated genes in GM-Mphage and M-Mphage, respectively. After the stimulation with BCG, 3 chemokine genes (Osteopontin (SPP1), CXC chemokine ligand 7 (CXCL7), and CC chemokine ligand 11 (CCL11)) were highly expressed in M-Mphage-BCG when compared to those in GM-Mf-BCG. A significantly increased resistance to M. tuberculosis H37Ra was observed after the stimulation of GM-Mphage with SPP1 or CXCL7. Superoxide production levels of SPP1- or CXCL7-stimulated GM-Mphages were higher than those of GM-Mphages without stimulation. These results indicate that both SPP1 and CXCL7 might have a role in the resistance against mycobacteria, at least in part, through augmenting reactive oxygen intermediates production in Mphages. Fluorescence signals for approximately 30,000 spots in slides were detected by fluorescent image analyzer FLA-8000 (Fuji film, Tokyo, Japan) for Cy3 and Cy5, separately. Hybridization intensities were processed using Arrayvision software ver. 6.0 (Imaging Research, Ontario, Canada). Signal and background intensities were determined by the median pixel values. Local background values were determined as the average of four background spots around each gene spot. All spots in the image (for both Cy3 and Cy5 signals) were evaluated for a possibility of dusts, to lower the probability of false data in all experiments. GeneSpring ver. 6.2. (Silicon genetics, Redwood city, CA) was used for data analysis. According to the GeneSpring instruction, normalization of the data was done using "Lowess method" [20]. Spots with dust, or with signal value of which the Cy5 or Cy3 channels were less than three times of background, were excluded.