Figure 2. In vivo and in vitro associations between endotoxin (LPS) levels and TLR4 mRNA expression in PBMCs.
(A) In samples obtained directly from HIV uninfected subjects, an inverse relationship between plasma LPS levels and TLR4 expression was apparent (R = −0.35, P = 0.053, Spearman Rank correlation). However, in HIV infected subjects no correlation or trend was seen (R = 0.029, P = 0.83). Additionally, plasma HIV RNA levels were positively associated with increased TLR4 mRNA levels (Spearman R = 0.3260, P = 0.049). (B) In a similar pattern, overnight culture with 0.1 ug/l LPS reduced TLR4 mRNA expression in PBMC of HIV uninfected (n = 70, P = 0.009), but not infected subjects (n = 21, P = 0.627). Isolated HIV ssRNA40 increased TLR4 mRNA expression in PBMC from HIV uninfected subjects (n = 70, P = 0.011), but not infected subjects (n = 21, P = 0.808). Spearman rank sum and Wilcoxon signed rank tests were used, two-tailed ns = not significant, t = trend(P<0.1),*P<0.05.