However, it is worth mentioning that in human plasma, LPS concentration ranges from undetectable levels up to 0.2 ng/mL (50–53), even in patients with systemic endotoxemia (50), but with LPS at this range, we were not able to observe increased inflammatory cytokine release or enhanced TLR4 protein expression in HT-29 cells. Here, TLR4 is linked to serum lipopolysaccharide activity.