Depressed CCL5 Expression in Human Pulmonary Tuberculosis

CCL5/regulated on activation, normal T expressed and secreted production (RANTES) is a principal CC chemokine, and can activate macrophages and Th1 lymphocytes, however, little is known about the CCL5 profiles associated with active tuberculosis (TB). In this study, we investigated the production of CCL5 by the peripheral blood mononuclear cells (PBMCs) of patients with active pulmonary TB after stimulation with Triton X-100 soluble proteins (TSP) or the 30-kDa antigen. The profiles of cytokines/chemokines [CXCL8/interleukin (IL)-8, IL-12 p40, and interferon (IFN)-gamma] were also examined by PBMCs from TB patients, and compared with those obtained from healthy tuberculin reactors (HTR). Concordant with earlier studies, IFN-gamma production was significantly depressed in the PBMCs from TB patients compared with those from HTR. In addition, the CCL5, but not CXCL8, levels in the PBMCs from TB patients were significantly depressed after stimulation for 18 hr compared to those in the PBMCs from HTRs. The CCL5 release was not significantly correlated with the release of IFN-gamma in the cells from TB patients and HTRs. Further, inhibitor studies show that the 30-kDa- or TSP-induced CCL5 mRNA expression is sensitive to inhibitors of mitogen-activated protein kinase kinase (MEK) 1/2 and Janus kinase (JAK) 2, but not p38, pathway activation, suggesting a MEK1/2- or JAK2-based mechanism is responsible for modulating of the CCL5 expression in human PBMCs. Collectively, these data suggest that TB patients show depressed production of CCL5 secretion, which can be modulated by MEK- and JAK2-based transcriptional regulatory mechanisms, in response to the mycobacterial antigens.

Elevated Levels of Interferon-inducible Protein-10 (IP)-10/CXCL10, but not of Interferon-gamma, in Patients with Pulmonary Tuberculosis

Mycobacterial strains are potent inducers of cytokines/chemokines by mononuclear phagocytes, which constitute an important cellular component of the first line of defense in the innate immune system. Interferon (IFN)-gamma-inducible protein (IP-10 or CXCL10) is a potent chemoattractant; however, little is known about the IP-10 profiles attributable to the Th1 regulation associated with active tuberculosis (TB). In this study, we investigated the production of IP-10, interleukin (IL)-12 p40, and IFN-gamma by the peripheral blood mononuclear cells (PBMCs) of patients with active pulmonary TB in response to in vitro stimulation with Triton X-100 soluble proteins (TSPs) or the 30-kDa antigen. The TSP antigens used in the present study were isolated and purified from Mycobacterium tuberculosis H37Rv (virulent strain), M. tuberculosis H37Ra (avirulent strain), and Mycobacterium bovis BCG. The results were compared with those obtained for healthy tuberculin reactors (HTRs). Concordant with earlier studies, IFN-gamma production was significantly depressed in the PBMCs from TB patients compared with those in the HTR group. However, the IP-10 levels in the PBMCs from TB patients were significantly elevated 18 h after stimulation compared to those in the PBMCs from HTRs. IP-10 release was correlated in a significant manner with the release of IFN-gamma in the HTRs, but this was not the case for the TB patients. Collectively, these data suggest that TB patients show altered regulation of Th1-driving cytokine and chemokine production in response to a variety of mycobacterial antigens.