Mycobacterial antigen-induced pro-inflammatory cytokines upregulated in DM-LTB cases
To investigate the effect of latent MTB infection on host immunity, we compared the levels of proinflammatory cytokines in the supernatants from purified protein derivative (PPD)- stimulated healthy and diabetic individuals with and without LTBi. Specifically, IFNγ, IL-6, IL-2, IL-12, TNF-α, GM-CSF, IL-1β and IL-18 levels were measured in supernatants of PPD-stimulated PBMCs in EC, LTBi, DM and DM-LTB groups.
PPD-stimulated IL-6 (p=0.011), IL-2 (p=0.0131), TNF-α (p=0.027) and GM-CSF (p=0.0075) levels were found to be significantly different between the study groups, Table 2. These cytokines were found to be raised in DM-LTB study subjects as compared with EC and/or LTBi and DM groups. IL-6 levels were significantly raised in DM-LTBi as compared with EC (p=0.0015) and LTB (p=0.0142). DM-LTBi cases had raised IL-2 levels as compared with EC (p۔0.0015), LTBi (p=0.0187) and DM (p=0.0388) cases. TNF-α levels were raised in DM-LTBi as compared with EC (p=0.0098), LTBi (p=0.0141) and DM (p=0.0118) cases. In DM-LTBi cases, GM-CSF levels were significantly raised as compared with EC (p=0.0014), LTBi (p=0.0394). GM-CSF levels were also raised in TB as compared with EC (p=0.0075) and LTBi (p=0.038). IL-1β levels were significantly raised in DM-LTB as compared with EC (p=0.0020). IL-18 levels were increased in DM-LTB as compared with EC (p=0.0090).
We observed that levels of IFN-γ showed an increased trend in DM-LTB as compared with EC, DM and LTB groups however, these were not significantly different.