Endogenous hydrogen sulfide and ERK1/2-STAT3 signaling pathway may participate in the association between homocysteine and hypertension

Background: Homocysteine (Hcy) is a risk factor for hypertension, although the mechanisms are poorly understood.

Methods: We first explored the relationship between Hcy levels and blood pressure (BP) by analyzing the clinical data of primary hypertensive patients admitted to our hospital. Secondly, we explored a rat model to study the effect of Hcy on blood pressure and the role of H₂S. An hyperhomocysteinemia (HHcy) rat model was induced to explore the effect of Hcy on blood pressure and the possible mechanism. We carried out tissue histology, extraction and examination of RNA and protein. Finally, we conducted cell experiments to determine a likely mechanism through renin-angiotensin-aldosterone system (RAAS) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway.

Results: In primary hypertensive inpatients with HHcy, blood pressure was significantly higher as compared with inpatient counterparts lacking HHcy. In the rat model, blood pressure of the Wistar rats was significantly increased with increases in serum Hcy levels and decreased after folate treatment. Angiotensin converting enzyme 1 (ACE1) expression in the Wistar Hcy group was enhanced comparing to controls, but was decreased in the Wistar folate group. Angiotensin II receptor type 1 (AGTR1) levels in the kidney tissue increased in the Wistar folate group. Both serum H₂S and kidney cystathionine γ-lyase decreased with elevated levels of serum Hcy. In vitro, increased concentrations and treatment times for Hcy were associated with increased expression of collagen type 1 and AGTR1. This dose and time dependent response was also observed for p-STAT3 and p-ERK1/2 expression.

Conclusion: Endogenous H₂S might mediate the process of altered blood pressure in response to changes in serum Hcy levels, in a process that is partly dependent on activated RAAS and ERK1/2-STAT3 signaling pathway.