Enhanced Mycobacterial Antigen–Induced Pro-Inflammatory Cytokine Production in Lymph Node Tuberculosis

Abstract

Lymph node tuberculosis (LNTB) is characterized by the enhanced baseline and antigen-specific production of type 1/17 cytokines and reduced baseline and antigen-specific production of interleukin (IL)-1β and IL-18 at the site of infection when compared with peripheral blood. However, the cytokine profile in the lymph nodes (LNs) of Mycobacterium tuberculosis culture-positive LNTB (LNTB+) and negative LNTB (LNTB−) has not been examined. To address this, we have examined the baseline and mycobacterial antigen-stimulated cytokine levels of type 1 (interferon gamma [IFNγ], tumor necrosis factor alpha [TNFα], IL-2), type 2 (IL-4, IL-5, and IL-13), type 17 (IL-17A, IL-17F, and IL-22), pro-inflammatory (IL-1α, IL-1β, IL-18, and granulocyte macrophage colony-stimulating factor [GM-CSF]), and regulatory cytokines (IL-10, transforming growth factor beta [TGF-β]) cytokines in the LN culture supernatants of LNTB+ and LNTB− individuals. We have observed significantly enhanced baseline levels of IL-13 and IL-10 and significantly reduced baseline levels of IL-4 and GM-CSF in LNTB+ individuals compared with LNTB− individuals. By contrast, we have observed significantly enhanced levels of type 1 (IFNγ, TNFα, and IL-2), type 17 (IL-17F and IL-22), and pro-inflammatory (IL-1α and GM-CSF) cytokines and significantly reduced levels of TGFβ in response to purified protein derivative, early secreted antigen-6, and culture filtrate protein-10 antigens in LNTB+ compared with LNTB− individuals. On phorbol 12-myristate 13-acetate/ionomycin stimulation, no significant difference was observed for any of the cytokines examined. Thus, our study revealed several interesting differences in the cytokine profiles of mycobacterial antigen-stimulated LN cultures in LNTB+ and LNTB− individuals. Therefore, we suggest the presence of mycobacteria plays a significant role in driving the cytokine response at the site of infection in LNTB.

Lymph nodes—The neglected battlefield in tuberculosis

“…When stimulated with Mtb-specific antigens, CFU+ lymph nodes had higher interleukin-10 (IL-10), T helper type 1 (Th1), T helper type 17 (Th17), and granulocyte-macrophage colony-stimulating factor (GMCSF) protein levels compared to CFU-lymph nodes from TBLN patients. No difference in levels of Th2 cytokines (IL-4, IL-5, and IL-13), IL-1β, or IL-18 was observed [66]. In contrast to other studies, Rahman and colleagues [67] showed that lymph nodes from children with TBLN had lower interferon alpha (IFNα), TNF, and IL-17 expression compared to non-TB-specific reactive lymph nodes and healthy tonsil controls.…”

“…Human studies investigating the immune response in Mtb-infected lymph nodes compared biopsied cervical lymph nodes of patients with TBLN with either healthy controls, patients with only pulmonary TB, and patients with other lymph node disease (e.g., cancer, non-TB-specific reactive lymphadenitis) [64][65][66][67]. All studies obtained transcription profiles, but only one study examined protein levels.…”

Dominant expansion of CD4+, CD8+ T and NK cells expressing Th1/Tc1/Type 1 cytokines in culture-positive lymph node tuberculosis

“…We recruited lymph node TB culture-positive (hereafter LNTB+, n = 18) and lymph node TB culture-negative (hereafter LNTB-, n = 10) patients and performed the experiments. The demographics and hematological data of the study population were reported previously [8] and the same set of lymph node (LN) samples was used for this study. LNTB+ group was characterized based on the excision biopsy exhibiting positive for Mycobacterium tuberculosis (Mtb) on liquid cultures and LNTB-(culture grades 0 [no or <19 colonies]) group was characterized based on the negative results for Mtb detection in liquid cultures.…”

“…The LN cells from LNTB+ and LNTB-individuals were isolated, cultured and either unstimulated, stimulated with Mtb (PPD [Staten's Serum Institute], ESAT-6, CFP10 [BEI resources, PLOS ONE 10 μg/mL]), non-Mtb (HIV Gag PP, (AIDS Reagent Program, Division of AIDS, NIAID, NIH), 10 μg/mL) and positive control (phorbol myristate acetate/Ionomycin [P/I], (Calbiochem, San Diego, CA), 12.5 and 125 ng/mL) antigens [8,9]. Before culturing, the LNs were transported in the Roswell Park Memorial Institute (RPMI)-1640 medium (Gibco) after biopsy and washed two times in RPMI 1640 medium.…”

“…We have previously shown lymph node TB culture-positive (LNTB+) individuals are associated with elevated Mtb antigen-induced levels of type 1, type 17, pro-inflammatory cytokines and reduced TGFβ levels upon comparison with lymph node TB culture-negative (LNTB−) individuals [8]. Similarly, LNTB patients displayed significantly reduced CD4 + , CD8 + T cells and natural killer (NK) cells expressing cytotoxic markers compared to peripheral blood [9].…”