title: Inflammation and hypertension: the interplay of interleukin-6, dietary sodium, and the renin-angiotensin system in humans.
abstract: BACKGROUND
  Prior evidence suggests a link between inflammation and hypertension. Interleukin-6 (IL-6) has been implicated in animal studies to play an important role in angiotensin II (ANGII)-mediated hypertension. The aim of this study was to examine the relationship of IL-6 and renin-angiotensin system (RAS) activity in human hypertension.
  
  
  METHODS
  Data from 385 hypertensives and 196 normotensives are included in this report. Blood pressure and laboratory evaluation were performed on liberal and low sodium diets. IL-6 response to an ANGII infusion was evaluated to assess the effect of acute RAS activation.
  
  
  RESULTS
  Hypertensives had higher baseline IL-6 and C-reactive protein (CRP) compared with normotensives on both diets. IL-6 increased in response to ANGII in hypertensives and normotensives (28% in hypertensives, 31% in normotensives, P ≤ 0.001 for change from baseline). In the setting of RAS activation by a low salt diet, multivariate regression analysis adjusted for age, body mass index (BMI), gender, race, and hypertension status demonstrated an independent positive association of plasma renin activity (PRA) with CRP (β = 0.199, P < 0.001). There was no significant difference in IL-6 or CRP levels between liberal and low sodium diets.
  
  
  CONCLUSIONS
  These findings confirm an association between hypertension and inflammation and provide human data supporting previous evidence from animal studies that IL-6 plays a role in ANGII-mediated hypertension. Notably, compared to levels on a liberal sodium diet, neither IL-6 nor CRP were higher with activation of the RAS by a low salt diet indicating that a low sodium diet is not inflammatory despite increased RAS activity.
authors.affiliation: Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's and Harvard Medical School, Boston, Massachusetts, USA. bchamarthi@partners.org
authors.forename: Bindu
authors.initials: B
authors.lastname: Chamarthi
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Williams
authors.forename: Vincent
authors.initials: V
authors.lastname: Ricchiuti
authors.forename: Nadarajah
authors.initials: N
authors.lastname: Srikumar
authors.forename: Paul N
authors.initials: PN
authors.lastname: Hopkins
authors.forename: James M
authors.initials: JM
authors.lastname: Luther
authors.forename: Xavier
authors.initials: X
authors.lastname: Jeunemaitre
authors.forename: Abraham
authors.initials: A
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000804:Angiotensin II / Q000494:pharmacology; D002097:C-Reactive Protein / Q000032:analysis; D004039:Diet, Sodium-Restricted; D005260:Female; D006801:Humans; D006973:Hypertension / Q000209:etiology*; D007249:Inflammation / Q000150:complications*; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000502:physiology*
chemical_list: D015850:Interleukin-6; D000804:Angiotensin II; D002097:C-Reactive Protein; D012083:Renin