Rat CRP Research Articles

Antidiabetic and hepatoprotection effect of butterfly pea flower (Clitoria ternatea L.) through antioxidant, anti-inflammatory, lower LDH, ACP, AST, and ALT on diabetes mellitus and dyslipidemia rat

This study explores the antidiabetic and hepatoprotective potential of Butterfly pea flower extract (Clitoria ternatea L.) (CTE) in diabetic and dyslipidemia rat models. Diabetes Mellitus (DM) is a chronic metabolic disorder marked by high levels of blood glucose, which can cause dyslipidemia and liver damage as a result of oxidative stress. CTE, a natural substance, is recognized for its positive attributes, such as anti-inflammatory, antioxidant, anti-diabetic, anti-dyslipidemia, antibiotic, and liver tissue protection capabilities. Dyslipidemia was induced in rats using a high-fat diet (HFD) and propylthiouracil (PTU) for 28 days. DM was induced using streptozotocin (STZ) and nicotinamide (NA). Rats were treated with varying doses of CTE for 28 days, along with glibenclamide and simvastatin. The research showed that CTE raised the levels of SOD, CAT, and liver proteins while lowering the levels of MDA, LDH, ACP, AST, ALT, IL-1β, and CRP in rats with DM and dyslipidemia. This suggests that CTE might be useful for treating DM.

Development of a New Benzofuran-Pyrazole-Pyridine-Based Molecule for the Management of Osteoarthritis.

Osteoarthritis is a substantial burden for patients with the disease. The known medications for the disease target the mitigation of the disease's symptoms. So, drug development for the management of osteoarthritis represents an important challenge in the medical field. This work is based on the development of a new benzofuran-pyrazole-pyridine-based compound 8 with potential anti-inflammatory and anti-osteoarthritis properties. Microanalytical and spectral data confirmed the chemical structure of compound 8. The biological assays indicated that compound 8 produces multifunctional activity as an anti-osteoarthritic candidate via inhibition of pro-inflammatory mediators, including RANTES, CRP, COMP, CK, and LPO in OA rats. Histopathological and pharmacokinetic studies confirmed the safety profile of the latter molecule. Accordingly, compound 8 is considered a promising anti-osteoarthritis agent and deserves deeper investigation in future trials.

The Effect of Interval Training on PTX3, VCAM-1, and CRP in Rats with Metabolic Syndrome

Background: Sedentary lifestyle and lack of exercise cause cardiovascular diseases and metabolic syndrome. Decreased movement in recent decades has caused cardiovascular diseases. Methods: In this research, 35 male Wistar rats weighing 220 ± 20 g were divided into 5 groups (seven rats in each group) by a simple random method. The first and second experimental groups were given 100 grams per liter of fructose with water for 6 weeks, and the third experimental group received this for 14 weeks. The training group performed the interval training protocol on the treadmill for eight weeks and 5 days a week. One-way analysis of variance (ANOVA) was used to compare the groups. Results: The use of the fructose diet for 6 weeks and 14 weeks caused metabolic syndrome in male Wistar rats. Induction of metabolic syndrome increased the plasma levels of PTX3, VACM-1, and CRP at the end of 6 weeks (P = 0.001, P = 0.018, and P = 0.004, respectively) and the fourteenth week (P = 0.001, P = 0.001, and P = 0.001, respectively). Eight weeks of interval training significantly reduced PTX3, VACM-1, and CRP (P = 0.034, P = 0.027 and P = 0.021, respectively). Conclusions: The fructose diet caused metabolic syndrome and a significant increase in inflammatory markers in rats, and high-intensity interval training significantly reduced inflammatory factors in them.

Effect of Biotin Treatment on the improvement of Lipid Profile and Foam Cells in Dyslipidemia rats

Introduction: This study aimed to assess the effects of increasing biotin concentrations on lipid profiles, CRP, and foam cells in Wistar rats with dyslipidemia risks. Materials and Methods: Thirty male Wistar rats (weighing 150-200grams) were divided into five groups and adapted for seven days. The negative control group received standard feed, while the positive control group received a high-fat diet. The treatment groups 1, 2, and 3 received a high-fat diet and biotin at different doses: 1.232mg/kg, 68.39mg/kg, and 97.72mg/kg, respectively, for six weeks. This study employed the colorimetric enzymatic method to examine the lipid profiles, a qualitative approach to examine the CRP, and painting Oil Red O and HE on histology slides to count the foam cells. Results: The negative control group indicated normal levels of lipid profiles and foam cells. The positive control group showed increased lipid profile levels and foam cells. Meanwhile, the treatment groups receiving an increase in biotin concentration showed a decreasing pattern of the foam cells, and their lipid profile levels (total cholesterol, triglycerides, and LDL) decreased. However, the HDL did not reduce. The results of all groups' CRP were negative. The one-way ANOVA test showed significance for the levels of total cholesterol, triglycerides, and LDL. The Kruskal-Wallis test was significant for the number of foam cells (a confidence level of 95%). Conclusion: The biotin treatment significantly improves Wistar rats' lipid profiles and the number of foam cells. However, the doses did not statistically affect the levels of HDL and CRP.

Euphorbium total triterpenes improve Freund's complete adjuvant-induced arthritis through PI3K/AKT/Bax and NF-κB/NLRP3 signaling pathways.

Euphorbium is the resinous secretion of Euphorbia resinifera Berg. According to the record, Euphorbium was first used by Roman doctors to treat the emperor's joint pain. In China, it is applied in folk medicine to treat damp-cold or mucous diseases, such as arthralgia and ascites, etc. This herb is used for rheumatoid arthritis and skin tumors in the folklore of northeastern Brazil. Triterpenes are mainly characteristic constituents of Euphorbium, and possibly possess anti-rheumatoid arthritis. To explore the preventive effect of Euphorbium total triterpenes (TTE) on Freund's complete adjuvant (FCA) induced arthritis in rats and its mechanism. TTE was extracted and isolated from Euphorbium, and its components were analyzed by HPLC. The safety of TTE was evaluated by an acute toxicity test in mice. Arthritis was induced in rats by injecting 0.2mL FCA into the right hind paw toe, except for the control group, which was given the same volume of physiological saline. Tripterygium Glycosides (TG, 7.5mg/kg) and TTE (32, 64 and 128mg/kg) were administered by gavage for 30 days. Body weights, paw swelling, and arthritic scores were measured during the experiment process. After 30 days, blood and joints were harvested to determine various indicators of arthritis. The contents of euphol and euphorbol in TTE were 47.03% and 18.77% respectively, and the maximal feasible dose of TTE in mice is 12 g/kg. The experimental results showed that arthritis indicators in rats deteriorated after FCA inducement compared with the control group. After treatment with TTE, the swelling degree and histopathological change of the hind paws in rats were significantly improved as well as arthritic score; the serum TNF-α, CRP, IL-1β, IL-6, IL-18 and RF levels in rats were significantly reduced; The expression of PI3K, AKT, P-AKT, Bcl-2, NF-κB, NLRP3 and Pro-caspase-1 protein in joint tissue were down-regulated, and the expression of Bax protein was up-regulated. The results suggested that TTE possessed anti-arthritis effects, and its mechanism may be related to its anti-inflammatory and immunomodulatory properties, as well as regulation of PI3K/AKT/Bax and NF-κB/NLRP3 signaling pathway.

Evaluating the anti-arthritic potential of walnut (Juglans regia L.) in FCA induced Sprague Dawley rats.

Rheumatoid arthritis (RA) is an autoimmune progressive disease, associated with many pathophysiological consequences. Owing to the adverse effects and higher costs of pharmaceuticals, people are now looking for complementary and alternative remedies. In this milieu, the present study was designed to explore the therapeutic potential of walnuts against FCA-induced arthritis in rat models. Purposely, 50 Sprague Dawley rats were housed in a well-ventilated animal room and separated into 5 groups of 10 rats each. The rats were categorized as G0 (negative control), G1 (positive control, i.e., FCA induced untreated arthritic rats), G2 (arthritic rats treated with MTX), G3 (arthritic rats treated with walnut feed), and G4 (arthritic rats treated with walnut extract), with an efficacy trial lasting for 42 days. The physical analysis explicated that paw swelling was significantly improved by 10%-12.8% in treatment groups after the intervention when compared with positive control. Moreover, biochemical analyses revealed significantly lower levels of ESR, CRP, and RF in rats treated with walnut-based interventions when compared to positive control. ESR values were decreased by 62.4% and 69.92% in G3 and G4 , whereas CRP levels were improved by 56.20% and 77.78% in G3 and G4 when compared with G1 . Likewise, RF values decreased in G2 , G3 , and G4 by 64.71%, 55.88%, and 69.24%, respectively when compared to G1 . The histological examination demonstrated the potential role of walnut-based interventions in reducing the severity of disease by decreasing cell infiltration, bone erosion, and paw inflammation. Meanwhile, the gene expression analysis revealed that walnut-based interventions protected the paw joints from damage by downregulating the RANKL-OPG pathway. Conclusively, walnut feed and extract may serve as potent anti-arthritic interventions with no side effects. PRACTICAL APPLICATIONS: Plant-based therapeutics are effective in the prevention and management of various chronic diseases. The current research explored the anti-arthritic potential of walnuts. Walnut feed and extract effectively reduced the serum arthritic biomarkers as well as downregulated the genes involved in bone destruction. Thus, the inclusion of dietary ingredients having therapeutic potential such as walnuts may be synchronized in clinical practices to ameliorate arthritis.

Evaluating the therapeutic potential of white button mushroom (Agaricus bisporus) against DMBA-induced breast cancer in Sprague Dawley rats.

The current research work was designed to investigate the protective effects of white button mushroom (Agaricus bisporus) against 7,12-dimethylbenz[a]anthracene (DMBA)-induced breast cancer. Breast cancer was induced in rats by the administration of a single dose of 50mg/kg DMBA via gavage. The rats were divided into four groups: G1 (negative control group), G2 (positive control group), G3 (rats receiving mushroom extract), and G4 (rats administered with doxorubicin). The mushroom extract significantly (p<.001) improved the activity of antioxidant enzymes in carcinogenic rats. Moreover, the mushroom extract also prevented the increase in the concentration of tumor biomarkers that are CEA, CA 15.3, and CRP in experimental rats. Liver function enzymes were also raised in G2 and G4 compared with G3. Besides, the RBCs and Hb were also reduced significantly in G4 while in G3. The mushroom extract effectively controlled the level of RBCs and Hb. An improvement in lipid profile was also measured in mushroom extract receiving rats. Conclusively, the mushroom extract alleviated DMBA-induced breast cancer potentially via improving antioxidants, reducing lipid peroxidation, and decreasing tumor biomarkers. PRACTICAL APPLICATIONS: The present research study examined the antitumor potential of white button mushroom. The mushroom effectively prevented the increase in tumor biomarkers, reduction in antioxidant enzymes, and increase in lipid peroxidation in rats with DMBA-induced breast cancer. The mushroom can be used as a potential source to prevent breast cancer and further research can be conducted to explore its anticancer mechanisms.

1-Methyl tryptophan, an indoleamine 2,3-dioxygenase inhibitor, attenuates cardiac and hepatic dysfunction in rats with biliary cirrhosis

Kynurenine Pathway (KP) is the dominant metabolic route of tryptophan which is catalyzed by indoleamine-2,3-dioxygenase (IDO). This pathway is upregulated in liver disease where the level of KP metabolites correlates with the severity of disease. Cirrhosis is associated with cardiac dysfunction, which manifests itself during severe physiological challenges such as liver transplantation. Cardiac dysfunction in cirrhosis is linked to systemic inflammation and impaired cardiac beta-adrenergic signaling pathways. The KP pathway is involved in modulation of cardiac signaling and is upregulated by systemic inflammation. Therefore, this study aimed to evaluate the effect of IDO inhibition on development of cardiac dysfunction in an experimental model of cirrhosis. Cirrhosis was induced by bile duct ligation (BDL). Experimental groups were given either 1-methyl tryptophan (1-MT, 1, 3, 9 mg/kg), or saline. 28 days after BDL, cardiac chronotropic response to epinephrine was assessed ex vivo. HPLC was employed to measure hepatic and cardiac levels of tryptophan, kynurenine and kynurenic acid. Cirrhosis in rats was associated with impaired cardiac chronotropic responsiveness to adrenergic stimulation. 1-MT dose-dependently improved cirrhosis-induced chronotropic dysfunction as well as elevated serum levels of CRP and IL-6 in BDL rats. Hepatic and cardiac kynurenine/tryptophan ratio were elevated in cirrhotic rats and were reduced following 1-MT administration. Chronic administration of 1-MT could also reduce hepatic inflammation, fibrosis and ductular proliferation. 1-MT attenuates cardiac dysfunction in rats with biliary cirrhosis. This protective effect is not limited to the cardiac function as liver histopathologic changes were also improved following chronic 1-MT administration.

Interactive Effects of Resistance Training and Genistein Consumption on the levels of VCAM, ICAM and CRP in Diabetic Rats with Streptozotocin

Interactive Effects of Resistance Training and Genistein Consumption on the levels of VCAM, ICAM and CRP in Diabetic Rats with Streptozotocin

Black mulberry ethanol extract attenuates atherosclerosis-related inflammatory factors and downregulates PPARγ and CD36 genes in experimental atherosclerotic rats.

Atherosclerosis (AS) is the pathological basis of various vascular diseases and currently is seriously affecting human health. Numerous studies have paid more attention to natural medicines with anti-AS properties. As a traditional Uygur folk medicine, black mulberry fruits are conventionally used in the prevention and treatment of cardiovascular diseases in southern Xinjiang of China, and their underlying mechanisms remain unknown. Our previous study revealed that the ethanol extract of black mulberry (EEBM) inhibited AS development by improving lipid metabolism abnormalities, enhancing anti-oxidative activities, and reducing atherosclerotic lesions of atherosclerotic rats. Based on this, our objective was to further investigate the effects of EEBM on the expression of AS-related inflammatory factors and the key genes PPARγ and CD36 of the ox-LDL-PPARγ-CD36 feed-forward cycle in experimental atherosclerotic rats. Black mulberry fruits were extracted with acid ethanol and chromatographed on an AB-8 macroporous resin to obtain EEBM. All experimental rats were randomly divided into five groups: normal, model, model plus simvastatin (5 mg/kg d·body weight), and model plus low-dose and high-dose EEBM groups (105 and 210 mg/kg d·body weight, respectively). Serum levels of the inflammatory factors were determined by enzyme-linked immunosorbent assay (ELISA). The mRNA and protein expression of PPARγ and CD36 in atherosclerotic rats' liver tissue and thoracic aorta were determined by Q-PCR and western blot analysis, respectively. EEBM at high dose effectively attenuated the abnormally expressed AS-related inflammatory factors of TNF-α, IL-6, MMP-9, and CRP in atherosclerotic rats by 41.5%, 66.1%, 77.5%, and 79.5%, respectively. After treatment with high dose EEBM, the elevated-expressions of PPARγ and CD36 at the mRNA and protein levels in atherosclerotic rats were found to be obviously downregulated at both levels. These results demonstrate that EEBM might lessen the AS-related inflammatory reaction, and then inhibit the formation of ox-LDL, consequently downregulating the expression of PPARγ and CD36 at the mRNA and protein levels, thus reducing macrophage-foam-cell formation and prohibiting the development of atherosclerotic plaque through the ox-LDL-PPARγ-CD36 feed-forward cycle, which can effectively prevent the occurrence and development of AS in atherosclerotic rats.

HIF1\u03b1 inhibition facilitates Leflunomide-AHR-CRP signaling to attenuate bone erosion in CRP-aberrant rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by progressive bone erosion. Leflunomide is originally developed to suppress inflammation via its metabolite A77 1726 to attenuate bone erosion. However, distinctive responsiveness to Leflunomide is observed among RA individuals. Here we show that Leflunomide exerts immunosuppression but limited efficacy in RA individuals distinguished by higher serum C-reactive protein (CRPHigher, CRPH), whereas the others with satisfactory responsiveness to Leflunomide show lower CRP (CRPLower, CRPL). CRP inhibition decreases bone erosion in arthritic rats. Besides the immunomodulation via A77 1726, Leflunomide itself induces AHR-ARNT interaction to inhibit hepatic CRP production and attenuate bone erosion in CRPL arthritic rats. Nevertheless, high CRP in CRPH rats upregulates HIF1α, which competes with AHR for ARNT association and interferes Leflunomide-AHR-CRP signaling. Hepatocyte-specific HIF1α deletion or a HIF1α inhibitor Acriflavine re-activates Leflunomide-AHR-CRP signaling to inhibit bone erosion. This study presents a precision medicine-based therapeutic strategy for RA.

Hepatocyte nuclear factors as possible C-reactive protein transcriptional inducer in the liver and white adipose tissue of rats with experimental chronic renal failure

Inflammation related to chronic kidney disease (CKD) is an important clinical problem. We recently determined that hepatocyte nuclear factor 1α (HNF1α) was upregulated in the livers of chronic renal failure (CRF) rats—experimental model of CKD. Considering that the promoter region of gene encoding C-reactive protein (CRP) contains binding sites for HNF1α and that the loss-of-function mutation in the Hnfs1α leads to significant reduction in circulating CRP levels, we hypothesized that HNF1α can activate the Crp in CRF rats. Here, we found coordinated upregulation of genes encoding CRP, interleukin-6 (IL-6), HNF1α, and HNF4α in the livers and white adipose tissue (WAT) of CRF rats, as compared to the pair-fed and control animals. This was accompanied by elevated serum levels of CRP and IL-6. CRP and HNFs’ mRNA levels correlated positively with CRP and HNFs’ protein levels in the liver and WAT. Similar upregulation of the Crp, Il-6, and Hnfs in the liver and WAT and increased serum CRP and IL-6 concentrations were found in lipopolysaccharide (LPS)-induced systemic inflammation in rats. Moreover, silencing HNF1α in HepG2 cells by small interfering RNA led to decrease in CRP mRNA levels. Our results suggests that (a) HNFs act in concert with IL-6 in the upregulation of CRP production by the liver and WAT, leading to an increase in circulating CRP concentration in CRF rats and (b) CRF-related inflammation plays an important role in the upregulation of genes that encode HNFs and CRP in the liver and WAT of CRF rats.

Taraxerol, a pentacyclic triterpenoid, from Abroma augusta leaf attenuates diabetic nephropathy in type 2 diabetic rats

Persistent hyperglycaemia coupled with inflammation plays an important role in the pathogenesis of diabetic nephropathy (DN). Present study examined the therapeutic potential of taraxerol isolated from the methanol extract of Abroma augusta leaf against DN using rodent model of type 2 diabetes (T2D). T2D was experimentally induced by high fat diet and a single low-single dose of streptozotocin (35mg/kg, i.p.). Accumulation of serum creatinine, urea, and uric acid, activation of lactate dehydrogenase and creatinin kinase, and release of urinary albumin represented the glomerular damage and the progression of nephropathy in T2D rats. Taraxerol (20mg/kg, p.o.) treatment significantly reinstated the aforementioned changes in biochemical parameters near to normalcy. Molecular mechanism studies demonstrated an impaired signaling cascade, IRS1/PI3K/Akt/AMPK/GLUT4/GSK3β, of glucose metabolism in the skeletal muscle and increase in serum levels of pro-inflammatory cytokines, CRP and MCP1 in T2D rats. Activation of polyol pathway, enhanced production of AGEs, up-regulation of NF-κB/PKCs/PARP signaling, and renal fibrosis was also observed in T2D rats. Taraxerol (20mg/kg, p.o.) treatment stimulated glucose metabolism in skeletal muscle, regulated blood glycaemic status and lipid profile in the sera, reduced the secretion of pro-inflammatory cytokines, and restored the renal physiology in T2D rats. Histological assessments were also in agreement with the above findings. Molecular docking study again supported the probable interactions of taraxerol with PKCβ, PKCδ, NF-κB, PARP, PI3K, IRS, Akt and AMPK. In silico ADME study predicted the drug-likeness character of taraxerol. Results suggest a possibility of taraxerol to be a new therapeutic agent for DN in future.

The Influence of Goat Milk and Soybean Milk Kefir On IL-6 and Crp Levels in Diabetic Rats

Abstract Background and Aims: Hyperglycemia increases inflammation in type 2 diabetes mellitus (T2DM). Goat and soybean milks have been known to reduce inflammation. The aim of this study is to evaluate the effect of goat milk and soybean milk kefir on IL-6 and CRP levels in diabetic rats. Materials and Method: A total of 25 male Wistar rats were divided into the following groups: 1) normal rats; 2) diabetic rats; 3) diabetic rats with intake of goat milk kefir; 4) diabetic rats with intake of soybean milk kefir; and 5) diabetic rats with combination of both types of kefir. Before kefir administration for 4 weeks, plasma glucose was measured. After treatment, plasma glucose, CRP and IL-6 levels were assessed. Results: There was a significant decline of plasma glucose in diabetic rats with goat milk kefir (p=0.021), and in diabetic rats with the combination of both goat milk and soybean milk kefir (p&lt;0.001). After treatment, CRP level in diabetic rats was significantly higher when compared with those that had goat milk kefir (p=0.043). All of diabetic rats with kefir had IL-6 values significantly lower than diabetic rats without it (p=0.021). Conclusion: Both goat milk and soybean milk kefir can reduce IL-6 level, but only goat milk kefir can reduce CRP in diabetic rats.

Hypoglycemic effect of polysaccharides with different molecular weight of Pseudostellaria heterophylla

sBackgroundThe aims of this study were to evaluate the antidiabetic activity and to detect molecular size of Pseudostellaria heterophylla polysaccharide (PHP). Pseudostellaria heterophylla is a medicine extensively used in traditional Chinese medicine formulas to treat diabetes and its complications.MethodsMolecular weight of PHP was determined by gel permeation chromatography combined with phenol-sulphuric acid method and the monosaccharides composition was determined by HPLC with a precolumn derivatization. Four polysaccharides with different molecular weight were compared for hypoglycemic active on two animal models both high does alloxan induced type1 diabetic mellitus (T1DM) and high-fat/lower does streptozotocin induced type2 diabetic mellitus (T2DM). Blood sugar, glucose tolerance, and insulin tolerance were detected. Rat serum IL-1β, IL-2, IL-10, Leptin, TNF-α, Acrp30 and CRP were also analyzed by sandwich-ELISA approaches to preliminary probe the hypoglycemic mechanism of PHP.ResultsThe hypoglycemic effects related to molecular size of polysaccharide were more effective against T2DM than T1DM. PHP comprise four monosaccharides of galacturonic acid, glucose, galactose and arabinos. T2DM rats daily receiving oral dose of polysaccharide(100 ~ 400 mg/kg) with 50 ~ 210 kDa molecular weight (PF40) could not only significantly lower blood sugar but also reduce total triglyceride level in serum. PF40 improves in insulin tolerance inhibited the expression of some biomarkers including inflammatory cytokine TNF-α and elevated anti-inflammatory cytokine IL-10, regulated adiponectin Acrp30 and leptin.ConclusionsPF40 prevent the cascade of inflammatory events in the treatment of T2DM to block overweight progresses to obesity.

EVALUATION OF THE EFFICIENCY AND SAFETY OF ADENO-ASSOCIATED VIRUS SEROTYPE 9 MEDIATED SERCA2A GENE TRANSFECTION TO MYOCARDIUM BY THREE CARDIAC GENE DELIVERY METHODS IN RATS

ObjectivesTo assess the efficiency and safety of adeno-associated virus serotype 9 (AAV9) mediated sarcoplasmic reticulum Ca2+ATPase 2a (SERCA2a) gene transfection to myocardium in normal SD rats by three cardiac gene...

Plasma turnover of 3,4-didehydroretinol (vitamin A2) increases in vitamin A-deficient rats fed low versus high dietary fat

Relationships between increased adiposity and fat-soluble vitamin storage and metabolism are poorly understood. To examine these associations, 6% or 21% dietary fat was fed to rats for 11 weeks and tissue vitamin A storage determined. Two levels of supplemental vitamin A were administered. At the end of the tenth week, 3,4-didehydroretinol (DR) was administered orally, and its kinetics were followed for 1 week in serum and tissues. Model-based compartmental analysis was applied to these data. Kidney total retinol (R) concentrations were elevated in rats fed 6% compared with 21% dietary fat (n = 24/group). The fractional transfer coefficient (FTC) describing the movement of tracer from plasma to extravascular stores was two times higher in the 6% compared with the 21% fat group. Consistent with the elevated renal R in 6% fat fed rats, there was a 2-fold increase in the FTC representing tracer distribution from plasma to kidney in the 6% compared with 21% fat group. Taken together with a fat main effect on renal vitamin A, our data support the evidence that faster turnover of kidney R may help set the mechanism governing vitamin A tissue distribution during deficiency. Rats fed 21% versus 6% dietary fat conserved hepatic R more efficiently.

Rat C-reactive protein activates the autologous complement system.

Activation of complement is a biological function of human C-reactive protein (hCRP), whereas rat CRP (rCRP) has been claimed to be unable to activate complement. As important biological functions of proteins are probably conserved among species, we re-evaluated, using various ligands, the capability of rCRP to activate complement. The activation of complement by hCRP and rCRP was investigated in solid- and fluid-phase systems. In the solid-phase system, purified CRP was fixed to enzyme-linked immunosorbent assay (ELISA) plates and incubated with human or rat recalcified plasma. Dose-dependent binding of human and rat C3 and C4 was observed to human and rat CRP, respectively. In the fluid-phase system, recalcified rat plasma, which contains about 500 mg/l of CRP, or human plasma supplemented with hCRP, were incubated with lyso-phosphatidylcholine. A dose-dependent activation of complement was observed upon incubation with this ligand, as reflected by the generation of activated C4 as well as of CRP-complement complexes. This activation was, in both cases, inhibited by preincubation of plasma with p-aminophosphorylcholine, a specific inhibitor of the interaction of CRP with its ligands, or by chelation of calcium ions. We conclude that rat CRP, similarly to human CRP, can activate autologous complement. These results support the notion that opsonization of ligands with complement is an important biological function of CRP.

Identification of rat alpha1 macroglobulin as an inhibitor of rat Galbeta1-4GlcNAc alpha2-6 sialyltransferase.

Rat serum was found to contain an inhibitor of pure alpha2-6 sialyltransferase (EC 2.4.99.1). The inhibitor was a high Mr protein isolated by molecular filtration on Sephadex G100, followed by anion exchange chromatography on Sephadex DEAE A25, then separation on Sepharose CL 4B, and finally by isoelectric focusing. Electrophoretic separation and subsequent N-terminal sequence analysis of the active inhibitor preparation showed the presence of two protein components, identified as rat C-reactive protein, and rat alpha1 macroglobulin. Pure rat CRP did not inhibit alpha2-6 sialyltransferase. Treatment of the inhibitor preparations with monospecific antibodies against rat alpha1 macroglobulin blocked inhibitory activity in a dose-dependent manner. The results present strong evidence that alpha1 macroglobulin is capable of acting as an inhibitor of alpha2-6 sialyltransferase. No inhibition of galactosyltransferase (EC 2.4.1.38) could be detected, indicating that the interaction with alpha1 macroglobulin may have specificity among the glycosyltransferases. The entrapment of alpha2-6 sialyltransferase by alpha1 macroglobulin presented here occurs in vitro and will require further in vivo investigations to determine the precise physiological significance. Independent of the physiologic significance is the finding that this interaction occurs in vitro, which, pending elucidation of the precise mechanism and specificity, may provide a new tool for investigations into the functional significance of sialylation, and potentially for use or design of new inhibitors of therapeutic value in physiologic conditions involving altered levels of sialylation.

A Novel Phosphatidylcholine Hydrolyzing Action of C-Reactive Protein

We have observed a novel time and dose dependent stimulatory effect of CRP on the hydrolysis of dipalmitoyl phosphatidylcholine (DPPC) into phosphorylcholine (P-choline) and diacylglycerol (DAG). This effect was shared by rat, rabbit, human and asialo-rat CRP but not by other serum proteins, i.e., albumin, ovalbumin and α1- acid glycoprotein. DPPC was also hydrolysed by normal rat serum (contains CRP) but not when serum was depleted of CRP. There is a requirement of Ca2+ for this unsuspected effect which was observed over a wide range of pH and the effect was markedly increased in temperatures up to 48 °C. The hydrolysis of DPPC showed a 3-fold decrease in Km when the assays included rat CRP. Massive increase of CRP in response to inflammation and its involvement in host defense reactions have been well documented. Significance of the present study rests on the possibility that the mechanism of action of CRP in cellular metabolism might be related to the production of DAG and P-choline known to have roles respectively in signal transduction and growth factor stimulated DNA synthesis.