Role of Ciliary Neurotrophic Factor in Angiotensin II-Induced Hypertension.

BACKGROUND

Ciliary neurotrophic factor (CNTF), mainly known for its neuroprotective properties, belongs to the IL-6 (interleukin-6) cytokine family. In contrast to IL-6, the effects of CNTF on the vasculature have not been explored. Here, we examined the role of CNTF in AngII (angiotensin II)-induced hypertension.

METHODS

Hypertension was chronically induced with AngII (1000 ng/kg per minute, osmotic mini-pumps, 14 days) in CNTF-knockout and wild-type mice (with or without nephrectomy and 1% NaCl drinking water). Blood pressure was measured by tail-cuff and radiotelemetry. Effects of CNTF on vascular function and the JAK2/STAT3 pathway were measured in vivo, in the isolated perfused kidney, and in mouse and human vascular smooth muscle cells.

RESULTS

At baseline, systolic blood pressure was similar between both groups. During AngII infusion, blood pressure increase was significantly attenuated and hypertensive heart and kidney damage was significantly attenuated in CNTF-knockout compared with wild-type mice. Accordingly, renal pressor response to AngII but not KCl or phenylephrine was significantly decreased in CNTF-knockout compared with wild-type mice. Acute CNTF (5 µmol/L) administration nearly restored the AngII-dependent renal pressor response. Chronic CNTF treatment in CNTF-knockout mice increased blood pressure response to AngII to levels observed in wild-type mice. CNTF augments AngII-induced activation of the JAK2/STAT3 pathway in vitro in vascular smooth muscle cells. The significance of this interaction was shown, as the increase in renal pressor response by CNTF was abolished by JAK2/STAT3 inhibitors.

CONCLUSIONS

Our results demonstrate a major impact of CNTF on blood pressure regulation by modulating AngII-induced pressor response via a JAK2/STAT3-dependent mechanism and indicate that CNTF is an important regulatory cytokine in hypertension.