Tuesday

C-Reactive Protein Inhibits Insulin Activation of Endothelial Nitric Oxide Synthase via the Immunoreceptor Tyrosine-Based Inhibition Motif of FcRIIB a

Keiji Tanigaki, Chieko Mineo, Ivan S. Yuhanna, Ken L. Chambliss, Michael J. Quon, Ezio Bonvini, Philip W. Shaul

Insulin promotes the cardiovascular protective functions of the endothelium including NO production by endothelial NO synthase (eNOS), which it stimulates via Akt kinase which phosphorylates eNOS Ser1179. C-reactive protein (CRP) is an acute-phase reactant that is positively correlated with cardiovascular disease risk in patients with type 2 diabetes.

We previously showed that CRP inhibits eNOS activation by insulin by blunting Ser1179 phosphorylation. We now elucidate the underlying molecular mechanisms. We first show in mice that CRP inhibits insulin-induced eNOS phosphorylation, indicating that these processes are operative in vivo. In endothelial cells we find that CRP attenuates insulin-induced Akt phosphorylation, and CRP antagonism of eNOS is negated by expression of constitutively active Akt; the inhibitory effect of CRP on Akt is also observed in vivo.

A requirement for the IgG receptor FcRIIB was demonstrated in vitro using blocking antibody, and reconstitution experiments with wild-type and mutant FcRIIB in NIH3T3IR cells revealed that these processes require the ITIM (immunoreceptor tyrosine-based inhibition motif) of the receptor. Furthermore, we find that endothelium express SHIP-1 (Src homology 2 domain–containing inositol 5'-phosphatase 1), that CRP induces SHIP-1 stimulatory phosphorylation in endothelium in culture and in vivo, and that SHIP-1 knockdown by small interfering RNA prevents CRP antagonism of insulin-induced eNOS activation.

Thus, CRP inhibits eNOS stimulation by insulin via FcRIIB and its ITIM, SHIP-1 activation, and resulting blunted activation of Akt. These findings provide mechanistic linkage among CRP, impaired insulin signaling in endothelium, and greater cardiovascular disease risk in type 2 diabetes.

C-reactive protein elicits white blood cell activation in humans.

C-Reactive Protein Study:
OBJECTIVE: Consistent epidemiologic evidence suggests that acute infections increase the risk for acute cardiovascular events. We tested in humans whether activation of peripheral leukocytes in reaction to the administration of recombinant human C-reactive protein (rhCRP) may provide a mechanism for infectious diseases to promote atherosclerotic disease.

METHODS AND RESULTS: By using quantitative real-time polymerase chain reaction analysis, whole-blood expression profiles were analyzed for 95 inflammatory markers before and after infusion of 1.25 mg/kg rhCRP in 5 male volunteers. Relevant transcript levels were measured at baseline and 4 and 8 hours after rhCRP-infusion. CRP caused significant up-regulation of matrix metalloproteinase (MMP)-9, monocyte chemoattractant protein (MCP)-1, plasminogen activator urokinase, macrophage inflammatory protein 1 alpha, and nuclear factor of kappa B inhibitor mRNAs in peripheral leukocytes. mRNA up-regulation of MMP-9 and MCP-1 was 17- and 11-fold, respectively. The corresponding increase in plasma protein levels of MMP-9 (78+/-32 ng/mL to 109+/-41 ng/mL; P=.014) and MCP-1 (312+/-92 pg/mL to 2590+/-898 pg/mL; P=.007) closely mirrored mRNA findings. Also, in whole-blood culture stimulation assays, CRP induced proinflammatory changes. Notably, heat inactivation abolished the capacity of CRP to evoke these proinflammatory changes, excluding a role for contaminants within the purified CRP preparation.

CONCLUSION: CRP elicits activation of peripheral leukocytes with ensuing secretion of plaque-destabilizing mediators. These findings are consistent with the hypothesis that infectious diseases trigger manifestations of atherosclerosis, in which CRP elevation might contribute to the onset of cardiovascular events.

Bisoendial RJ, Birjmohun RS, Akdim F, van 't Veer C, Spek CA, Hartman D, de Groot ER, Bankaitis-Davis DM, Kastelein JJ, Stroes ES.
Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands

Thursday

Are there Bi-directional Associations between Depressive Symptoms and C-Reactive Protein in Mid-life Women?

OBJECTIVE: To test whether depressive symptoms are related to subsequent C-reactive protein (CRP) levels and/or whether CRP levels are related to subsequent depressive symptoms in mid-life women. METHODS: Women enrolled in the Study of Women's Health Across the Nation (SWAN) were followed for seven years and had measures of CES-Depression scores and CRP seven times during the follow-up period. Women were pre- or early peri-menopausal at study entry and were of Caucasian, African American, Hispanic, Japanese, or Chinese race/ethnicity. Analyses were restricted to initially healthy women.

RESULTS: Longitudinal mixed linear regression models adjusting for age, race, site, time between exams, and outcome variable at year X showed that higher CES-D scores predicted higher subsequent CRP levels and vice versa over a 7-year period. Full multivariate models adjusting for body mass index, physical activity, medications, health conditions, and other covariates showed that higher CRP levels at year X predicted higher CES-D scores at year X+1, p = 0.03. Higher depressive symptoms predicted higher subsequent CRP levels at marginally significant levels, p=0.10.

CONCLUSIONS: Higher CRP levels led to higher subsequent depressive symptoms, albeit the effect was small. The study demonstrates the importance of considering bi-directional relationships for depression and other psychosocial factors and risk for heart disease.

Matthews KA, Schott LL, Bromberger JT, Cyranowski JM, Everson-Rose SA, Sowers M.
University of Pittsburgh, 3811 O'Hara Street, Pittsburgh, PA 15213

Wednesday

C-Reactive Protein: Fitness level and body composition are associated with inflammation in non-obese children

Childhood obesity and poor fitness are associated with insulin resistance (IR), risk for coronary heart disease (CHD), and type 2 diabetes mellitus. Elevated markers of inflammation (e.g., C-reactive protein [CRP]) are independent predictors of CHD. Whether higher percent body fat and poor fitness in non-obese children are associated with evidence of inflammation and IR is unclear.

We evaluated 75 children with non-obese body mass index (BMI) for age (<95th percentile), ages 11-14 years for fasting insulin, glucose, adiponectin, CRP, body composition, and maximum oxygen-consumption (VO2max). CRP correlated positively with body composition (BMI z-score, p = 0.00062; percent body fat, p = 0.00007; and total body fat in grams, p = 0.00006) and negatively with VO2max, p = 0.036. Using multivariate analysis, VO2max and percent body fat were both independent predictors of CRP. Fasting insulin and insulin resistance as assessed by QUICKI did not correlate with CRP, fitness, or fatness in these non-obese children.

Adiponectin showed no significant correlations, and gender did not influence correlation analyses. We conclude that in non-obese children, low fitness and higher body fat are both associated with inflammation (i.e., higher levels of CRP). This observation strengthens the importance of promoting both fitness and healthy body composition in all children.

Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI 54650, USA.

Tuesday

C-Reactive Protein Is a Determinant of First-Ever Stroke: Prospective Nested Case-Referent Study

Background and Purpose: C-reactive protein ,(CRP) is a determinant of stroke, but there are no prospective studies on CRP and first ischemic stroke divided into etiologic subtypes. Our primary aim was to study C-reactive protein as a determinant of ischemic stroke, classified according to Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria, and intracerebral hemorrhage (ICH) in a prospective study. A secondary aim was to study the relationship between the 1444C>T polymorphism, plasma levels of C-reactive protein and stroke. Methods: The study was a prospective population-based case-referent study nested within the Northern Sweden Cohorts. We defined 308 cases of ischemic stroke and 61 ICH. Two controls for each case were defined from the same cohort. Results: The OR for the highest (>3 mg/l) versus lowest group (<1 mg/l) of CRP was 2.58 (95% CI 1.74-3.84) for ischemic stroke and 1.63 (95% CI 0.67-3.93) for ICH. In a multivariate model including traditional risk factors, CRP remained associated with ischemic stroke (OR 2.06; 95% CI 1.29-3.29). Small-vessel disease was associated with C-reactive protein CRP in the multivariate model (OR 3.88; 95% CI 1.10-13.7). The C-reactive protein 1444 (CC/CT vs. TT) polymorphism was associated with plasma levels of C-reactive protein but neither with ischemic stroke nor with ICH. Conclusions: This prospective population-based study shows that CRP is significantly associated with the risk of having a first ischemic stroke, especially for small-vessel disease. No significant associations were found between the CRP 1444C>T polymorphism and any stroke subtype.

Jonas Sven Olof Andersson
Department of Medicine and Geriatrics
SkellefteƄ County Hospital
SE-931 86 SkellefteƄ (Sweden

Friday

Evaluation Of C-Reactive Protein

An evaluation of the association between C-reactive protein , the change in C-reactive protein over one year, and all-cause mortality in chronic immune-mediated inflammatory disease managed in UK general practice.

Objectives. To evaluate the association between systemic inflammation , as measured by (CRP), , and all-cause mortality. To also evaluate the association between change in CRP status (sub-acute, 10 mg/l and acute >10 mg/l) and all-cause mortality.

Methods. A cohort of patients was selected from The Health Improvement Network (THIN) data set of anonymized patient-level data from UK general practice. Patients were selected if they had a diagnosis of RA, psoriasis, AS or PsA. Survival was evaluated using " Cox proportional hazards regression models (CPHMs).

Results. A total of 11 362 cases had at least one CRP measurement. Analysis grouped by each additional unit increase in log-CRP (range 1–6) across the observed range was associated with a 21% increase in the hazard ratio (HR) of death, after controlling for cardiovascular risk factors (P < 0.001). This observation was consistent in separate analysis of cases with either RA or psoriasis. Repeated CRP observations around 1 yr apart were recorded in 2802 subjects. After controlling for confounding factors, in cases whose CRP changed from sub-acute (10 mg/l) to acute (>10 mg/l), the HR for death increased 2-fold (P < 0.001) relative to cases whose CRP remained sub-acute. In comparison, among those subjects whose CRP was reduced from acute to sub-acute, the HR was virtually identical to those who stayed sub-acute (P = 0.571).

Conclusions. C-reactive protein ( level predicted all-cause mortality after standardization for traditional risk factors, as did change in CRP status from sub-acute to acute observed over 1 yr.


KEY WORDS: C-reactive protein, Systemic inflammation, Survival, Rheumatoid arthritis, Psoriasis, Ankylosing spondylitis, Psoriatic arthritis

Rheumatology 2009 48(1):78-82; doi:10.1093/rheumatology/ken415