Circulating Interferon-Gamma Levels Are Associated with Low Body Weight in Newly Diagnosed Kenyan Non-Substance Using Tuberculosis Individuals

Abstract

Although interferon-gamma, interleukin-10, and adiponectin are key immunopathogenesis mediators of tuberculosis, their association with clinical manifestations of early stage disease is inconclusive. We determined interferon-gamma, interleukin-10, and adiponectin levels in clinically and phenotypically well-characterised non-substance using new pulmonary tuberculosis patients (n = 13) and controls (n = 14) from Kenya. Interferon-gamma levels (P < 0.0001) and interferon-gamma to interleukin-10 (P < 0.001) and interferon-gamma to adiponectin (P = 0.027) ratios were elevated in tuberculosis cases. Correlation analyses in tuberculosis cases showed associations of interferon-gamma levels with body weight (ρ = -0.849; P < 0.0001), body mass index (ρ = 0.664; P = 0.013), hip girth (ρ = -0.579; P = 0.038), and plateletcrit (ρ = 0.605; P = 0.028); interferon-gamma to interleukin-10 ratio with diastolic pressure (ρ = -0.729; P = 0.005); and interferon-gamma to adiponectin ratio with body weight (ρ = -0.560; P = 0.047), body mass index (ρ = -0.604; P = 0.029), and plateletcrit (ρ = 0.793; P = 0.001). Taken together, our results suggest mild-inflammation in early stage infection characterised by upregulation of circulating interferon-gamma production in newly infected TB patients.

Figure 1

Circulating cytokine levels in new tuberculosis (TB) cases (n = 13) and controls (n = 14). (a) Circulating interferon-gamma (IFN-γ) levels in TB cases and controls. (b) Circulating interleukin-10 (IL-10) levels in TB cases and controls. (c) Circulating adiponectin (Acrp30) levels in TB cases and controls. Data are presented as box plots, where the box represents the interquartile range, the line through the box represents the median, whiskers indicate the 10th and 90th percentiles, and the closed circles represent outliers. Statistical comparisons were performed using the Mann-Whitney U test. IFN-γ levels (pg/mL) were elevated in TB cases compared to controls (P < 0.0001). IL-10 (pg/mL; P = 0.125) and adiponectin (ng/mL; P = 0.544) levels were similar between the TB cases and controls.

Figure 2

Circulating cytokine ratios in new tuberculosis (TB) cases (n = 13) and controls (n = 14). (a) Circulating interferon-gamma (IFN-γ) to interleukin-10 (IL-10) ratio in TB cases and controls. (b) Circulating IFN-γ to adiponectin (Acrp30) ratio in new TB cases and controls. (c) Circulating IL-10 to adiponectin (Acrp30) ratio in new TB cases and controls. Data are presented as box plots, where the box represents the interquartile range, the line through the box represents the median, whiskers indicate the 10th and 90th percentiles, and the closed circles represent outliers. Statistical comparisons were performed using the Mann-Whitney U test. IFN-γ to IL-10 ratios were higher in the TB cases relative to controls (P < 0.001). IFN-γ to adiponectin ratios were also increased in TB cases relative to controls (P = 0.027). IL-10 to adiponectin ratios were similar in TB cases relative to controls (P = 0.423).