Effect Of Human C-reactive Protein Research Articles

Small Interfering-RNA to Protein Kinase C-Delta Reduces the Proinflammatory Effects of Human C-Reactive Protein in Biobreeding Diabetic Rats

Type 1 diabetes (T1DM) is a proinflammatory state characterized by increased C-reactive protein (CRP) levels. Previously we reported that human CRP accentuated macrophage activity in spontaneously diabetic biobreeding (BB) rats and also increased protein kinase C (PKC) delta. Hence we tested the effect of molecular inhibition of PKC delta on plasma and macrophage proinflammatory biomarkers using small interfering (si)RNA to PKC delta. Prior to administration of human CRP, daily for 3 days to diabetic rats, scrambled siRNA or siRNA to PKC delta was also delivered for the 3 days, and the animals were sacrificed on day 4. Peritoneal macrophages and plasma were obtained. Compared to scrambled siRNA, siRNA to PKC delta resulted in a significant decrease in biomediators of inflammation in plasma and from macrophages (IL-1, TNF-alpha, IL-6, MCP-1, KC/IL-8, and PAI -1). However, siRNA to PKC delta has no effect on superoxide release from macrophages. In conclusion, our novel data suggests that siRNA to PKC delta attenuates the proinflammatory effect of human CRP in spontaneously diabetic BB rats and could have implications with regard to attenuating inflammation and vascular complications in T1DM.

Antisense to protein kinase C-alpha and p47phox attenuates the pro-inflammatory effects of human C-reactive protein in macrophages of biobreeding diabetic rats

Type 1 diabetes mellitus (T1DM) is a pro-inflammatory state characterized by high C-reactive protein (CRP) levels. Previously, we showed that CRP accentuated a macrophage (MO) activity in spontaneously diabetic biobreeding (BB) rats and increased the MO activity of protein kinase C-alpha (PKC-α) and p47phox. In this report, we tested the effects of molecular inhibition of CRP effects on MO activity using antisense oligonucleotide (ASO) to both PKC-α and p47phox. Prior to administration of human C-reactive protein (hCRP) daily for 3 days, ASO or scrambled ASO to either PKC-α or p47phox was also delivered for 3 days and after killing on day 4, peritoneal MOs were isolated. The increase in the levels of superoxide anion, interleukin (IL)-1, monocyte chemoattractant protein-1 (MCP-1), tumour necrosis factor-alpha (TNF-α) and IL-6 release in MOs with hCRP compared to human albumin was significantly attenuated by antisense to either PKC-α and p47phox (p < 0.01 vs. scrambled ASO; n = 5 per group). Our novel data suggest that antisense to either PKC-α or p47phox attenuates the pro-inflammatory effects of human CRP on MOs in diabetic rats.

Effects of Human C-Reactive Protein on Pathogenesis of Features of the Metabolic Syndrome

Major controversy exists as to whether increased C-reactive protein (CRP) contributes to individual components of the metabolic syndrome or is just a secondary response to inflammatory disease processes. We measured blood pressure and metabolic phenotypes in spontaneously hypertensive rats (SHRs) in which we transgenically expressed human CRP in the liver under control of the apolipoprotein E promoter. In transgenic SHRs, serum levels of human CRP approximated the endogenous levels of CRP normally found in the rat. Systolic and diastolic blood pressures measured by telemetry were 10 to 15 mm Hg greater in transgenic SHRs expressing human CRP than in SHR controls (P<0.01). During oral glucose tolerance testing, transgenic SHRs exhibited hyperinsulinemia compared with controls (insulin area under the curve: 36±7 versus 8±2 nmol/L per 2 hours, respectively; P<0.05). Transgenic SHRs also exhibited resistance to insulin stimulated glycogenesis in skeletal muscle (174±18 versus 278±32 nmol of glucose per gram per 2 hours; P<0.05), hypertriglyceridemia (0.84±0.05 versus 0.64±0.03 mmol/L; P<0.05), reduced serum adiponectin (2.4±0.3 versus 4.3±0.6 mmol/L; P<0.05), and microalbuminuria (200±35 versus 26±5 mg of albumin per gram of creatinine, respectively; P<0.001). Transgenic SHRs had evidence of inflammation and oxidative tissue damage with increased serum levels of interleukin 6 (36.4±5.2 versus 18±1.7 pg/mL; P<0.005) and increased hepatic and renal thiobarbituric acid reactive substances (1.2±0.09 versus 0.8±0.07 and 1.5±0.1 versus 1.1±0.05 nmol/L per milligram of protein, respectively; P<0.01), suggesting that oxidative stress may be mediating adverse effects of increased human CRP. These findings are consistent with the hypothesis that increased CRP is more than just a marker of inflammation and can directly promote multiple features of the metabolic syndrome.

Overexpression of Human C-Reactive Protein Exacerbates Left Ventricular Remodeling in Diabetic Cardiomyopathy

C-reactive protein (CRP) is known to be a pathogenic agent in the cardiovascular system. However, the effect of CRP on heart failure has not been elucidated. The effect of human CRP on cardiac dysfunction induced by diabetes mellitus (DM) using human CRP-overexpressing transgenic mice (CRP-Tg) was examined. DM was induced in male wild-type mice (Wt/DM) and CRP-Tg (CRP/DM) by an injection of streptozotocin. Non-diabetic wild-type mice (Wt/Con) and CRP-Tg (CRP/Con) served as controls. Echocardiography and hemodynamic measurements 6 weeks after injection showed lower fractional shortening and left ventricular (LV) dP/dt max in CRP/DM compared with Wt/DM. Myocardial mRNA levels of interleukin-6, tumor necrosis factor-α, plasminogen activator inhibitor-1, angiotensin type 1 receptor, angiotensinogen, NADPH oxidase subunits (p47(phox), gp91(phox)), glutathione peroxidase-3. and connective tissue growth factor were increased in CRP/DM compared with Wt/DM. Nuclear staining of 8-hydroxydeoxyguanosine was also increased in CRP/DM compared with Wt/DM. CRP/DM was associated with increased terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling positive cells and a higher ratio of Bax/Bcl-2 proteins compared with Wt/DM. The extent of cardiac fibrosis assessed by Sirius red staining and immunohistochemical staining for collagen type 1 was significantly increased in CRP/DM compared with Wt/DM. Overexpression of human CRP exacerbates LV dysfunction and remodeling in diabetic cardiomyopathy, possibly through enhancement of the inflammation, renin-angiotensin system, and oxidative stress.

Inhibition of Experimental Autoimmune Encephalomyelitis in Human C-Reactive Protein Transgenic Mice Is FcRIIB Dependent

We showed earlier that experimental autoimmune encephalomyelitis (EAE) in human C-reactive protein (CRP) transgenic mice (CRPtg) has delayed onset and reduced severity compared to wild-type mice. Since human CRP is known to engage Fc receptors and Fc receptors are known to play a role in EAE in the mouse, we sought to determine if FcγRI, FcγRIIb, or FcγRIII was needed to manifest human CRP-mediated protection of CRPtg. We report here that in CRPtg lacking either of the two activating receptors, FcγRI and FcγRIII, the beneficial effects of human CRP are still observed. In contrast, if CRPtg lack expression of the inhibitory receptor FcγRIIB, then the beneficial effect of human CRP is abrogated. Also, subcutaneous administration of purified human CRP stalled progression of ongoing EAE in wild-type mice, but similar treatment failed to impede EAE progression in mice lacking FcγRIIB. The results reveal that a CRP → FcγRIIB axis is responsible for protection against EAE in the CRPtg model.

Effect of human C-reactive protein on cardiac function and angiotensin 2 signaling in diabetic cardiomyopathy

Effect of human C-reactive protein on cardiac function and angiotensin 2 signaling in diabetic cardiomyopathy

Inflammation and Endothelial Function: Direct Vascular Effects of Human C-Reactive Protein on Nitric Oxide Bioavailability

Inflammation and Endothelial Function: Direct Vascular Effects of Human C-Reactive Protein on Nitric Oxide Bioavailability

CRP or not CRP? That Is the Question

C-reactive protein (CRP) and cardiovascular disease is a very hot topic at present. Excitement and interest have spilled over dramatically from the scientific literature into the media and popular press leading to much speculative comment. However, rigorously controlled and reproducible studies are now laying the basis for a more realistic consensus. The article in this issue of Arteriosclerosis, Thrombosis, and Vascular Biology from Carmen van den Berg’s laboratory makes a notable contribution to this process. 1 See page 1225 Shortly after its discovery in 1929 as “the acute phase protein,” increased production of CRP was recognized as a characteristic feature of the response to acute myocardial infarction, and until the 1960’s detection of CRP was widely used for routine monitoring of acute rheumatic fever. In 1961 Irving Kushner, in one of the first applications of the then new technique of immunofluorescence, demonstrated the deposition of rabbit CRP in experimental myocardial infarction lesions. The association between CRP and cardiovascular disease thus has a very long history. In 1979 Kushner reported the kinetics of the acute phase CRP response to human acute myocardial infarction, and soon afterward we first investigated critically the behavior of CRP in clinical coronary artery disease and myocardial infarction.2 We observed that persistently elevated circulating CRP concentrations after an infarct were associated with a poor prognosis, although at that time we were focusing mainly on CRP as a sensitive nonspecific marker of all the various complications of coronary occlusion and their treatment. The current phase of interest in CRP and cardiovascular disease started in the early 1990’s with observations of increased CRP concentrations in some patients with “active coronary syndromes” and some individuals with acute myocardial infarction tested very soon after onset of pain, before the acute phase response to infarction could have started. These findings were consistent with the growing recognition at that time of the importance of inflammation in atherogenesis and the inflammatory nature of unstable atherosclerotic lesions. At the same time the large European prospective study (ECAT) of coagulation factors as possible prognostic markers in outpatients with stable and unstable angina unexpectedly revealed that the baseline value of CRP, which had only been included as a control for the acute phase behavior of some clotting proteins, significantly predicted future coronary events.3 The assay used was insufficiently sensitive to detect CRP in many of the samples in the ECAT study, and we therefore developed the first automated high-sensitivity method to re-assay their 3000 samples. Separately we also used this method to study, in collaboration with the Maseri group, carefully characterized patients with severe unstable angina who had not yet experienced any myocardial necrosis. We selected a cut point of 3 mg/L as the upper limit of normal, based on our original 1981 study of 468 healthy volunteer blood donors in whom this was the 90th centile of the CRP distribution. 4 In both the ECAT and the unstable angina studies, increased baseline CRP values were associated with significantly increased risk of future coronary events. 5,6 Subsequently several groups showed independently that baseline CRP measurements are associated with future coronary events in general populations, without known preexisting coronary artery disease. 7–10 In 2000 we reported with Danesh and colleagues the results from the British Regional Heart Study comprising 506 coronary events, 2 as many as in any other such study up to that time, together with a meta-analysis of all previous studies.11 This showed that the relative risk of having a coronary event among individuals with a baseline CRP value in the upper compared with the lower tertile of the CRP distribution was 2.0. In 2004 the Reykjavik Study, comprising 2459 coronary events, showed this relative risk to be 1.45 (95% CI, 1.25 to 168), and meta-analysis of all previously published general populations studies, comprising 7068 patients with coronary events, gave a similar result. 12 The results from this now quite rigorously

Effect of Human C-Reactive Protein on Chemokine and Chemotactic Factor-Induced Neutrophil Chemotaxis and Signaling

C-reactive protein (CRP) is a unique serum pentraxin and the prototype acute phase reactant. CRP is a ligand for specific receptors on phagocytic leukocytes, and mediates activation reactions of monocytes/macrophages, but inhibits the respiratory burst of neutrophils (PMN). Since CRP selectively accumulates at inflammatory sites in which IL-8 is also produced, we tested the effects of CRP on the responsiveness of PMN to IL-8 and the bacterial chemotactic peptide, FMLP-phenylalanine (FMLPP). Purified human CRP inhibited the chemotactic response of PMN to IL-8 and FMLPP. A mouse IgM mAb that was generated against the leukocyte CRP receptor (CRP-R) also inhibited the chemotactic response. Incubation of purified CRP with activated PMN generated CRP-derived peptides that also inhibited chemotaxis. A synthetic CRP peptide (residues 27-38) that binds to the CRP-R had weak chemotactic activity, whereas two other CRP synthetic peptides (residues 174-185 and 191-205) inhibited chemotaxis of PMNs to both IL-8 and FMLPP. CRP did not alter receptor-specific binding of IL-8, but exerted its effect at the level of signaling. CRP augmented both IL-8- and FMLPP-induced mitogen-activated protein kinase (extracellular signal-regulated kinase-2) activity. CRP at acute phase levels increased both agonist-induced and noninduced phosphatidylinositol-3 kinase activity. The results suggest a role for CRP as a regulator of leukocyte infiltration at inflammatory sites.

The effect of human C-reactive protein on the cell-attachment activity of fibronectin and laminin

We have previously reported that purified human C-reactive protein (CRP) specifically binds to the cell-binding region of plasma fibronectin (Fn) in a Ca 2+-dependent reaction that is saturable at a molar ratio of CRP/Fn of approximately 9. In this study, the binding of CRP to Fn was found to interfere with the cell-attachment promoting activity of Fn. The inhibition of cell attachment was dependent on the concentration of the CRP and involved the phosphorylcholine (PC) binding site of CRP since inhibition was prevented by allowing the CRP to react with either PC (or closely related monophosphate compounds) or a mAb specific for the PC-binding site of CRP. Binding of CRP to laminin was also Ca 2+-dependent; however, this binding did not alter the cell-attachment promoting activity of laminin. CRP by itself does not mediate cell attachment. Since CRP is selectively deposited at sites of tissue damage along with plasma Fn and has the ability to bind to Fn and alter its cell-binding activity, CRP may modulate early events in tissue repair.

Effect of C-reactive protein on peritoneal macrophages. I. Human C-reactive protein inhibits migration of guinea pig peritoneal macrophages.

The effect of human C-reactive protein (CRP) isolated and purified from pooled patients' sera on macrophage function, especially on macrophage migration, was studied. Peritoneal exudate cells (PEC) from guinea pigs were used for macrophage migration inhibition (MMI) test of capillary method. Migration of either PEC or adherent purified macrophages exposed to CRP were inhibited dose-dependently. These findings indicate that CRP inhibits macrophage migration directly, not via activation of lymphocytes contained in PEC. As control, we examined the effect of normal human serum, anti C-polysaccharide antibodies isolated from patients' sera, and free endotoxin at the dose contaminated in CRP preparation on macrophage migration and found that none of them were effective. The effect of CRP on MMI of sensitized PEC exposed to antigen was also studied. Large amounts of CRP inhibited MMI induced by antigen, indicating the possibility that CRP may act on macrophages competitively with migration inhibitory factor (MIF) and may modulate MMI. CRP possesses MIF-like activity and may play a functional role at the site of tissue injury by causing the accumulation of macrophages.

Effect of C-reactive protein on peritoneal macrophages. II. Human C-reactive protein activates peritoneal macrophages of guinea pigs to release superoxide anion in vitro.

The effect of human C-reactive protein (CRP) on macrophage function was studied in an assay of superoxide anion (O2-) production. Peritoneal exudate macrophages (PEM) of guinea pigs exposed in vitro to various doses of CRP for 72 hr resulted in the development of O2- production dose-dependently, measured by increases in superoxide dismutase-inhibitable nitro blue tetrazolium reduction. The O2--producing activity of PEM cultured without CRP, used as a control, decreased markedly in proportion to incubation time. The O2- production by PEM exposed to CRP for 18 hr when control PEM were still high in O2- production, was decreased by larger doses of CRP, while PEM cultured without CRP for 72 hr, when O2- production by control PEM was very low, followed by incubation with CRP for another 18 hr, produced O2- CRP-dose-dependently as in the case of that observed after 72-hr incubation with CRP. These results indicate that CRP is capable of activating macrophages and acts on macrophage function as a modulator. CRP possesses migration inhibitory factor (MIF)-like activity (as reported in the preceding paper) and also macrophage-activating factor (MAF)-like activity, indicating that CRP may play a functional role at the site of inflammation and tissue damage by accumulating and activating macrophages.

The Effects of Human C-reactive Protein on the Antibody Response to Pneumococcal C-polysaccharide

The Effects of Human C-reactive Protein on the Antibody Response to Pneumococcal C-polysaccharide

Inhibitory effect of human C-reactive protein (CRP) on the antibody response in mice to pneumococcal C-polysaccharide

Inhibitory effect of human C-reactive protein (CRP) on the antibody response in mice to pneumococcal C-polysaccharide

Effect of C-reactive protein on normal human leukocytes.

Conclusions and summaryOn the basis of studies using the slide cell technic to determine the effect of human C-reactive protein on normal human leukocytes, the following conclusions are indicated. 1. Purified human C-reactive protein in final concentrations higher than 0.005 mg/cc destroys normal human leukocytes. 2. Purified human C-reactive protein in lower concentrations stimulates the migration of normal human leukocytes. 3. C carbohydrate, sodium citrate, and normal human serum protein do not stimulate normal human leukocytes in the concentrations employed in this study. 4. The acute phase human sera tested caused increased migration of normal human leukocytes by virtue of their content of C-reactive protein. 5. Human serum diminishes at least in part in the toxic effect of the C-reactive protein on normal human leukocytes.