Abstract

The upregulated kinin B₁ receptors exert a pivotal role in modulating inflammatory processes. In isolated human umbilical veins (HUVs), kinin B₁ receptor is upregulated as a function of in vitro incubation time and proinflammatory stimuli. The aim of this study was to evaluate, using functional and biochemical methods, the involvement of extracellular signal-regulated kinase 5 (ERK5), p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase 1/2 (ERK1/2) on the kinin B₁ receptor upregulation process in HUV. Real-time polymerase chain reaction analysis revealed for the first time that kinin B₁ receptor mRNA expression closely parallels the functional sensitization to kinin B₁ receptor selective agonist des-Arg¹⁰-kallidin (DAKD) in HUV. Moreover, the selective inhibition of ERK5, p38 MAPK, and JNK, but not ERK1/2, produced a dose-dependent rightward shift of the concentration-response curves to DAKD after 5-hour incubation and a reduction in kinin B₁ receptor mRNA expression. Biochemical analyses showed that ERK5, p38 MAPK, and JNK phosphorylation is maximal during the first 2 hours postisolation, followed by a significant reduction in the last 3 hours. None of the treatments modified the responses to serotonin, an unrelated agonist, suggesting a specific effect on kinin B₁ receptor upregulation. The present work provides for the first time pharmacologic evidence indicating that ERK5 plays a significant role on kinin B₁ receptor upregulation. Furthermore, we confirm the relevance of p38 MAPK and JNK as well as the lack of effect of ERK1/2 in this process. This study may contribute to a better understanding of MAPK involvement in inflammatory and immunologic diseases.