TLR4 and hypertensive disorder: Considering the concept that inflammation is closely linked to hypertension and that the role of innate immune system, represented by TLR4 activation, in hypertension is still unclear, we hypothesized that TLR4 is up-regulated in SHR resistance arteries and its increased activation contributes to both increased vascular response to contractile stimuli and augmented blood pressure levels in SHR.