pCRP-mCRP Dissociation Mechanisms as Potential Targets for the Development of Small-Molecule Anti-Inflammatory Chemotherapeutics

The influences of ApoE isoforms on endothelial adherens junctions and actin cytoskeleton responding to mCRP

Apolipoprotein E4 (ApoE4) plays an important role responding to monomeric C-reactive protein (mCRP) via binding to CD31 leading to cerebrovascular damage and Alzheimer's disease (AD). Using phosphor-proteomic profiling, we found altered cytoskeleton proteins in the microvasculature of AD brains, including increased levels of hyperphosphorylated tau (pTau) and the actin-related protein, LIMA1. To address the hypothesis that cytoskeletal changes serve as early pathological signatures linked with CD31 in brain endothelia in ApoE4 carriers, ApoE4 knock-in mice intraperitoneal injected with mCRP revealed that mCRP increased the expressions of phosphorylated CD31 (pCD31) and LIMA1, and facilitate the binding of pCD31 to LIMA1. mCRP combined with recombinant APOE4 protein decreased interaction of CD31 and VE-Cadherin at adherens junctions (AJs), along with altered the expression of various actin cytoskeleton proteins, causing microvasculature damage. Notably, the APOE2 protein attenuated these changes. Overall, our study demonstrates that ApoE4 responds to mCRP to disrupt the endothelial AJs which link with the actin cytoskeleton and this pathway could play a key role in the barrier dysfunction leading to AD risk.

Brain Vascular Expression of Monomeric C-Reactive Protein Is Blocked by C10M Following Intraperitoneal Injection in an ApoE-/- Murine Model of Dyslipidemia: An Immunohistochemical Analysis

Introduction The neurovascular unit (NVU), comprising vascular and glial cells along with neurons, is vital for maintaining the blood-brain barrier (BBB) and cerebral homeostasis. Dysfunction of the NVU is implicated in key neurodegenerative disorders such as Alzheimer's disease (AD). Monomeric C-reactive protein (mCRP), the dissociated form of native, pentameric C-reactive protein (pCRP), is associated with enhanced pro-inflammatory responses in the vascular system, leading to increased permeability and potential NVU disruption. Methods This study utilized ApoE-/- mice receiving a high-fat diet which were injected intraperitoneally with either mCRP or mCRP together with a small molecule inhibitor (C10M) and investigated the deposition of mCRP and CD105 expression in the brain parenchyma and its localization within the microvasculature. Results Histological analysis revealed significant mCRP deposition in brain microvessels and neurons, indicating potential disruption of the BBB and neuronal damage. Moreover, co-administration of C10M effectively blocked mCRP accumulation in the brain parenchyma, suggesting its potential as a therapeutic agent for effectively inhibiting inflammation-associated degenerative changes. Immunohistochemical staining demonstrated co-localization of mCRP with CD105, indicating potential angiogenic activation and increased susceptibility to inflammatory insult. Discussion These findings provide evidence supporting the potential role of mCRP as a contributor to neuroinflammation in individuals with chronic systemic inflammation. Conclusion Further studies in human subjects should help validate the efficacy of C10M in preventing or halting neurodegeneration in conditions such as AD and stroke-associated dementia.

Resveratrol Activates Antioxidant Protective Mechanisms in Cellular Models of Alzheimer's Disease Inflammation

Resveratrol is a natural phenolic compound with known benefits against neurodegeneration. We analyzed in vitro the protective mechanisms of resveratrol against the proinflammatory monomeric C-reactive protein (mCRP). mCRP increases the risk of AD after stroke and we previously demonstrated that intracerebral mCRP induces AD-like dementia in mice. Here, we used BV2 microglia treated with mCRP for 24 h in the presence or absence of resveratrol. Cells and conditioned media were collected for analysis. Lipopolysaccharide (LPS) has also been implicated in AD progression and so LPS was used as a resveratrol-sensitive reference agent. mCRP at the concentration of 50 µg/mL activated the nitric oxide pathway and the NLRP3 inflammasome pathway. Furthermore, mCRP induced cyclooxygenase-2 and the release of proinflammatory cytokines. Resveratrol effectively inhibited these changes and increased the expression of the antioxidant enzyme genes Cat and Sod2. As central mechanisms of defense, resveratrol activated the hub genes Sirt1 and Nfe2l2 and inhibited the nuclear translocation of the signal transducer NF-ĸB. Proinflammatory changes induced by mCRP in primary mixed glial cultures were also protected by resveratrol. This work provides a mechanistic insight into the protective benefits of resveratrol in preventing the risk of AD induced by proinflammatory agents.

Monomeric C-reactive protein: A novel biomarker predicting neurodegenerative disease and vascular dysfunction

Circulating C-reactive protein (pCRP) concentrations rise dramatically during both acute (e.g., following stroke) or chronic infection and disease (e.g., autoimmune conditions such as lupus), providing complement fixation through C1q protein binding. It is now known, that on exposure to the membranes of activated immune cells (and microvesicles and platelets), or damaged/dysfunctional tissue, it undergoes lysophosphocholine (LPC)-phospholipase-C-dependent dissociation to the monomeric form (mCRP), concomitantly becoming biologically active. We review histological, immunohistochemical, and morphological/topological studies of post-mortem brain tissue from individuals with neuroinflammatory disease, showing that mCRP becomes stably distributed within the parenchyma, and resident in the arterial intima and lumen, being "released" from damaged, hemorrhagic vessels into the extracellular matrix. The possible de novo synthesis via neurons, endothelial cells, and glia is also considered. In vitro, in vivo, and human tissue co-localization analyses have linked mCRP to neurovascular dysfunction, vascular activation resulting in increased permeability, and leakage, compromise of blood brain barrier function, buildup of toxic proteins including tau and beta amyloid (Aβ), association with and capacity to "manufacture" Aβ-mCRP-hybrid plaques, and, greater susceptibility to neurodegeneration and dementia. Recently, several studies linked chronic CRP/mCRP systemic expression in autoimmune disease with increased risk of dementia and the mechanisms through which this occurs are investigated here. The neurovascular unit mediates correct intramural periarterial drainage, evidence is provided here that suggests a critical impact of mCRP on neurovascular elements that could suggest its participation in the earliest stages of dysfunction and conclude that further investigation is warranted. We discuss future therapeutic options aimed at inhibiting the pCRP-LPC mediated dissociation associated with brain pathology, for example, compound 1,6-bis-PC, injected intravenously, prevented mCRP deposition and associated damage, after temporary left anterior descending artery ligation and myocardial infarction in a rat model.

Peripheral apolipoprotein E proteins and their binding to LRP1 antagonize Alzheimer's disease pathogenesis in the brain during peripheral chronic inflammation

C-reactive protein (CRP) impacts apolipoprotein E4 (ApoE4) allele to increase Alzheimer's disease (AD) risk. However, it is unclear how the ApoE protein and its binding to LRP1 are involved. We found that ApoE2 carriers had the highest but ApoE4 carriers had the lowest concentrations of blood ApoE in both humans and mice; blood ApoE concentration was negatively associated with AD risk. Elevation of peripheral monomeric CRP (mCRP) reduced the expression of ApoE in ApoE2 mice, while it decreased ApoE-LRP1 binding in the brains of ApoE4 mice that was characterized by Proximity Ligation Assay. Both serum ApoE and brain ApoE-LRP1 binding were positively associated with the expression of pericytes that disappeared after mCRP treatment, and negatively associated with brain tauopathy and neuroinflammation in the presence of mCRP. In ApoE-/- mice, mCRP reduced the brain expression levels of synaptophysin and PSD95 and the positive relationship between ApoE-LRP1 binding and synaptophysin or PSD95 expression disappeared. Our study suggests that blood ApoE protects against AD pathogenesis by binding to LRP1 during peripheral chronic inflammation.

Association of C-reactive protein and complement factor H gene polymorphisms with risk of lupus nephritis in Chinese population

BACKGROUND

Complement overactivation is a major driver of lupus nephritis (LN). Impaired interactions of C-reactive protein (CRP) with complement factor H (CFH) have been shown as a pathogenic mechanism that contributes to the overactivation of complement in LN. However, genetic variations of neither CRP nor CFH show consistent influences on the risk of LN.

AIM

To examine whether genetic variations of CRP and CFH in combination can improve the risk stratification in Chinese population.

METHODS

We genotyped six CRP single nucleotide polymorphisms (SNPs) (rs1205, rs3093062, rs2794521, rs1800947, rs3093077, and rs1130864) and three CFH SNPs (rs482934, rs1061170, and rs1061147) in 270 LN patients and 303 healthy subjects.

RESULTS

No linkage was found among CRP and CFH SNPs, indicating lack of genetic interactions between the two genes. Moreover, CRP and CFH SNPs, neither individually nor in combination, are associated with the risk or clinical manifestations of LN. Given the unambiguous pathogenic roles of the two genes.

CONCLUSION

These findings suggest that the biological effects of most genetic variations of CRP and CFH on their expressions or activities are not sufficient to influence the disease course of LN.

Photonic sensor to detect rapid changes in CRP levels

One of the most important biomarkers used to determine inflammation is C-reactive protein (CRP). Its level, when it is within the range that does not define inflammation, informs about the risk of cardiovascular events. If the norm is exceeded and inflammation is detected in the body, CRP level can increase 1000 times within a few hours. The type of infection can also be determined based on the level of elevated CRP. All this makes CRP a very important element of diagnostics. A sensor based on low coherence interference is presented. Preliminary studies have shown that its sensitivity is 5.65 μg/L and the measurement time is short, <10 min. The entire system is built of commercially available components, which allow production cost minimalization. In addition, the user-friendly operation allows it to be operated by unqualified people. Due to these features, our solution is a promising alternative to commercially used enzyme-linked immunosorbent assay, which needs trained personnel to perform time-consuming measurement procedures.

Relevance of lipoproteins, membranes, and extracellular vesicles in understanding C-reactive protein biochemical structure and biological activities

Early purification protocols for C-reactive protein (CRP) often involved co-isolation of lipoproteins, primarily very low-density lipoproteins (VLDLs). The interaction with lipid particles was initially attributed to CRP’s calcium-dependent binding affinity for its primary ligand—phosphocholine—the predominant hydrophilic head group expressed on phospholipids of most lipoprotein particles. Later, CRP was shown to additionally express binding affinity for apolipoprotein B (apo B), a predominant apolipoprotein of both VLDL and LDL particles. Apo B interaction with CRP was shown to be mediated by a cationic peptide sequence in apo B. Optimal apo B binding required CRP to be surface immobilized or aggregated, treatments now known to structurally change CRP from its serum soluble pentamer isoform (i.e., pCRP) into its poorly soluble, modified, monomeric isoform (i.e., mCRP). Other cationic ligands have been described for CRP which affect complement activation, histone bioactivities, and interactions with membranes. mCRP, but not pCRP, binds cholesterol and activates signaling pathways that activate pro-inflammatory bioactivities long associated with CRP as a biomarker. Hence, a key step to express CRP’s biofunctions is its conversion into its mCRP isoform. Conversion occurs when (1) pCRP binds to a membrane surface expressed ligand (often phosphocholine); (2) biochemical forces associated with binding cause relaxation/partial dissociation of secondary and tertiary structures into a swollen membrane bound intermediate (described as mCRP_m or pCRP*); (3) further structural relaxation which leads to total, irreversible dissociation of the pentamer into mCRP and expression of a cholesterol/multi-ligand binding sequence that extends into the subunit core; (4) reduction of the CRP subunit intrachain disulfide bond which enhances CRP’s binding accessibility for various ligands and activates acute phase proinflammatory responses. Taken together, the biofunctions of CRP involve both lipid and protein interactions and a conformational rearrangement of higher order structure that affects its role as a mediator of inflammatory responses.

Monomeric C-reactive protein induces the cellular pathology of Alzheimer's disease

Introduction

Human study shows that elevated C-reactive protein (CRP) in blood impacts apolipoprotein E (APOE) ε4, but not APOE ε3 or APOE ε2, genotype to increase the risk of Alzheimer's disease (AD). However, whether CRP is directly involved in cellular AD pathogenesis and in which type of neuronal cells of APOE ε4 carriers are unknown.

Methods

We aimed to use different primary neuronal cells and investigate if CRP induces cellular AD pathology depending on APOE genotypes. Here the different primary neuronal cells from the different APOE genotype knock-in mice cortex were isolated and used.

Results

Monomeric CRP (mCRP) increased amyloid beta production and, in parallel, induced tau phosphorylation in addition to their related proteins in the primary neurons in a pattern of APOE ε4 > APOE ε3 > APOE ε2 in a dose- and time-dependent manner. Consistently, mCRP induced the staining of other neurodegenerative biomarkers, including Fluoro-Jade B stain (FjB), TUNEL and Cleaved Caspase-3, in primary neurons in a similar pattern of APOE ε4 > APOE ε3 > APOE ε2. In contrast, pentameric CRP (pCRP) had a tendency to induce cellular AD pathology but did not reach statistical significance. On the other hand, it is intriguing that regardless of APOE genotype, mCRP did not influence the expressions of Iba-1 and CD68 in primary microglia or the expression of glial fibrillary acidic protein in primary astrocytes, and additionally mCRP did not affect the secretions of interleukin (IL)-1α, IL-1β, and tumor necrosis factor α from these cells.

Discussion

This is the first report to demonstrate that mCRP directly induces cellular AD pathogenesis in neurons in an APOE genotype-dependent pattern, suggesting that mCRP plays a role as a mediator involved in the APOE ε4-related pathway for AD during chronic inflammation.

Highlights

Pentameric C-reactive protein (pCRP) can be dissociated irreversibly to form free subunits or monomeric CRP (mCRP) during and after the acute phase.mCRP increased amyloid beta production in the primary neurons in a pattern of apolipoprotein E (APOE) ε4 > APOE ε3 > APOE ε2 in a dose-dependent manner.mCRP induced the expression of phosphorylated tau in the primary neurons in a pattern of APOE ε4 > APOE ε3 > APOE ε2 in a dose- and time-dependent manner.mCRP plays an important mediator role in the APOE ε4-related pathway of Alzheimer's disease risk.

mCRP as a Biomarker of Adult-Onset Still’s Disease: Quantification of mCRP by ELISA

Background

C-reactive protein (CRP) is a dynamic protein that undergoes conformational changes between circulating native pentameric CRP (pCRP), pentameric symmetrical forms (pCRP*) and monomeric (or modified) CRP (mCRP) forms. mCRP exhibits strong pro-inflammatory activity and activates platelets, leukocytes, and endothelial cells. Abundant deposition of mCRP in inflamed tissues plays a role in several disease conditions, such as ischemia/reperfusion injury, Alzheimer’s disease, and cardiovascular disease. Although pCRP is typically quantified rather than mCRP for clinical purposes, mCRP may be a more appropriate disease marker of inflammatory diseases. Therefore, simple methods for quantifying mCRP are needed.

Methods

We developed a specific enzyme-linked immunosorbent assay (ELISA) to measure plasma levels of mCRP. Plasma mCRP concentration was measured in patients with adult-onset Still’s disease (AOSD) (n=20), polymyalgia rheumatica (PMR) (n=20), rheumatoid arthritis (RA) (n=30), infection (n=50), and in control subjects (n=30) using the developed ELISA.

Results

We demonstrated that mCRP is elevated in some inflammatory autoimmune diseases, particularly AOSD. The mCRP concentration was also significantly higher among AOSD patients than RA, PMR patients and controls (477 ng/ml, 77 ng/ml, 186 ng/ml, and 1.2 ng/ml, respectively). Also, the mCRP (×1,000)/pCRP ratio was significantly higher among AOSD patients than RA, PMR, and infection patients (3.5, 0.6, 1,6, and 2.0, respectively).

Conclusion

The plasma mCRP levels are elevated in some autoimmune diseases, particularly AOSD. The plasma mCRP levels may therefore be a potentially useful biomarker for AOSD.

CRP Serum Levels Are Associated with High Cardiometabolic Risk and Clinical Disease Activity in Systemic Lupus Erythematosus Patients

Systemic lupus erythematosus (SLE) patients have a higher frequency of cardiovascular risk factors such as high C-reactive protein (CRP) levels than the general population. CRP is considered a cardiovascular disease marker that could be related to SLE clinical disease activity. This study aimed to assess the association between CRP with cardiometabolic risk and clinical disease activity in SLE patients. A comparative cross-sectional study was conducted in 176 female SLE patients and 175 control subjects (CS) with median ages of 38 and 33 years, respectively; SLE patients were classified by the 1997 SLE-ACR criteria, and the clinical disease activity by the Mexican-SLEDAI (Mex-SLEDAI). CRP and lipid profile (triglycerides, cholesterol, HDL-C, and LDL-C) were quantified by turbidimetry and colorimetric-enzymatic assays, respectively. SLE patients had higher CRP levels than CS (SLE: 5 mg/L vs. CS = 1.1 mg/L; p < 0.001). In SLE patients, CRP levels ≥ 3 mg/L were associated with a higher risk of cardiometabolic risk status assessed by LAP index (OR = 3.01; IC: 1.04−8.7; p = 0.04), triglycerides/HDL-C index (OR = 5.2; IC: 2.1−12.8; p < 0.001), Kannel index (OR = 3.1; IC: 1.1−8.1; p = 0.03), Castelli index (OR = 6.6; IC: 2.5−17.8; p < 0.001), and high clinical disease activity (OR = 2.5: IC: 1.03−6.2; p = 0.04; and β coefficient = 5.8; IC: 2.5−9.4; R2 = 0.15; p = 0.001). In conclusion, high CRP levels were associated with high cardiometabolic risk and clinical disease activity in SLE patients.

Monomeric C-Reactive Protein: Current Perspectives for Utilization and Inclusion as a Prognostic Indicator and Therapeutic Target

Monomeric C-reactive protein (mCRP), once thought to be a figment of the imagination and whose biological activity was ascribed to its sodium azide preservative, has now pronounced itself as a critical molecule playing a direct role in mediating many of the acute and chronic aberrant pathological responses to inflammation. In this focused mini review, we describe the currently attributed pathobiological interactions of mCRP in disease, where its tissue and cellular distribution and deposition have recently been clearly characterized and linked to inflammation and other pathway-associated progression of neurological and cardiovascular complications and deleterious outcomes. and focus upon current opinions as to the diagnostic and prognostic potential of mCRP-plasma circulating protein and define the possible future therapeutics including ongoing research attempting to block CRP dissociation with small molecule inhibitors or prevention of cell surface binding directly using antibodies or modified orphan drug targeting directed towards CRP, inhibiting its cellular interactions and signaling activation. There is no doubt that understanding the full influence of the biological power of mCRP in disease development and outcome will be considered a critical parameter in future stratified treatment.

C-reactive protein as a potential biomarker in psychiatric practice: Are we there yet?

OBJECTIVES

Serum or plasma levels of C-reactive protein (CRP) and high-sensitivity CRP (hsCRP) are widely used clinical markers of inflammation in other branches of medicine, whereas its clinical use in psychiatry has been limited to research studies. We aimed to assess the possibility of using CRP/hsCRP in psychiatric practice. This is a review and evaluation of various lines of evidence supporting the concept of CRP as a biomarker for psychiatric disorders in certain conditions.

METHODS

We searched the literature for studies which assessed CRP/hsCRP levels in various psychiatric disorders.

RESULTS

The accumulating evidence from large studies and meta-analyses allows us to understand the role of CRP in major psychiatric disorders and increase our understanding of specific symptoms and subtypes of disorders. CRP may be considered a 'psychiatric biomarker' which can alert clinicians about neuroinflammation, adverse effects of medications, cardiometabolic status, co-morbidities, and may also predict clinical outcomes and guide optimal treatment.selection.

CONCLUSION

Although the underlying pathophysiological role of CRP and hsCRP is still elusive and the association between CRP and psychiatric disorders is inconsistent, CRP holds promise to become a psychiatric biomarker.

Monomeric C-reactive protein via endothelial CD31 for neurovascular inflammation in an ApoE genotype-dependent pattern: A risk factor for Alzheimer's disease?

In chronic peripheral inflammation, endothelia in brain capillary beds could play a role for the apolipoprotein E4 (ApoE4)‐mediated risk for Alzheimer's disease (AD) risk. Using human brain tissues, here we demonstrate that the interactions of endothelial CD31 with monomeric C‐reactive protein (mCRP) versus ApoE were linked with shortened neurovasculature for AD pathology and cognition. Using ApoE knock‐in mice, we discovered that intraperitoneal injection of mCRP, via binding to CD31 on endothelial surface and increased CD31 phosphorylation (pCD31), leading to cerebrovascular damage and the extravasation of T lymphocytes into the ApoE4 brain. While mCRP was bound to endothelial CD31 in a dose‐ and time‐dependent manner, knockdown of CD31 significantly decreased mCRP binding and altered the expressions of vascular‐inflammatory factors including vWF, NF‐κB and p‐eNOS. RNAseq revealed endothelial pathways related to oxidative phosphorylation and AD pathogenesis were enhanced, but endothelial pathways involving in epigenetics and vasculogenesis were inhibited in ApoE4. This is the first report providing some evidence on the ApoE4‐mCRP‐CD31 pathway for the cross talk between peripheral inflammation and cerebrovasculature leading to AD risk.

Anti-Monomeric C-Reactive Protein Antibody Ameliorates Arthritis and Nephritis in Mice

Conformation-specific Ags are ideal targets for mAb-based immunotherapy. Here, we demonstrate that the monomeric form of C-reactive protein (mCRP) is a specific therapeutic target for arthritis and nephritis in a murine model. Screening of >1800 anti-mCRP mAb clones identified 3C as a clone recognizing the monomeric, but not polymeric, form of CRP. The anti-mCRP mAb suppressed leukocyte infiltration in thioglycollate-induced peritonitis, attenuated rheumatoid arthritis symptoms in collagen Ab-induced arthritis model mice, and attenuated lupus nephritis symptoms in MRL/Mp-lpr/lpr lupus-prone model mice. These data suggest that the anti-mCRP mAb 3C has therapeutic potential against rheumatoid arthritis and lupus nephritis.

Impact of C-Reactive Protein on Cognition and Alzheimer Disease Biomarkers in Homozygous APOE ɛ4 Carriers

BACKGROUND AND OBJECTIVES

Previous research has shown that elevated blood C-reactive protein (CRP) is associated with increased Alzheimer disease (AD) risk only in APOE ε4 allele carriers; the objective of this study was to examine the interactive effects of plasma CRP and APOE genotype on cognition and AD biomarkers.

METHODS

Data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) study were analyzed, including APOE genotype; plasma CRP concentrations; diagnostic status (i.e., mild cognitive impairment and dementia due to AD); Mini-Mental State Examination (MMSE) and Clinical Dementia Rating Dementia Staging Instrument scores; CSF concentrations of β-amyloid peptide (Aβ42), total tau (t-Tau) and phosphorylated tau (p-Tau); and amyloid (AV45) PET imaging. Multivariable regression analyses tested the associations between plasma CRP and APOE on cognitive and biomarker outcomes.

RESULTS

Among 566 ADNI participants, 274 (48.4%) had no, 222 (39.2%) had 1, and 70 (12.4%) had 2 APOE ε4 alleles. Among only participants who had 2 APOE ε4 alleles, elevated CRP was associated with lower MMSE score at baseline (β [95% confidence interval] -0.52 [-1.01, -0.12]) and 12-month follow-up (β -1.09 [-1.88, -0.17]) after adjustment for sex, age, and education. The interaction of 2 APOE ε4 alleles and elevated plasma CRP was associated with increased CSF levels of t-Tau (β = 11.21, SE 3.37, p < 0.001) and p-Tau (β = +2.74, SE 1.14, p < 0.01). Among those who had no APOE ε4 alleles, elevated CRP was associated with decreased CSF t-Tau and p-Tau. These effects were stronger at the 12-month follow-up.

DISCUSSION

CRP released during peripheral inflammation could be a mediator in APOE ε4-related AD neurodegeneration and serve as a drug target for AD.

Recognized and Potentially New Biomarkers-Their Role in Diagnosis and Prognosis of Cardiovascular Disease

Atherosclerosis and its consequences are the leading cause of mortality in the world. For this reason, we have reviewed atherosclerosis biomarkers and selected the most promising ones for review. We focused mainly on biomarkers related to inflammation and oxidative stress, such as the highly sensitive C-reactive protein (hs-CRP), interleukin 6 (IL-6), and lipoprotein-associated phospholipase A2 (Lp-PLA2). The microRNA (miRNA) and the usefulness of the bone mineralization, glucose, and lipid metabolism marker osteocalcin (OC) were also reviewed. The last biomarker we considered was angiogenin (ANG). Our review shows that due to the multifactorial nature of atherosclerosis, no single marker is known so far, the determination of which would unambiguously assess the severity of atherosclerosis and help without any doubt in the prognosis of cardiovascular risk.

Monomeric C-Reactive Protein - A Feature of Inflammatory Disease Associated With Cardiovascular Pathophysiological Complications?

Monomeric C-reactive protein (mCRP), the dissociated form of native C-reactive protein, is a critical molecule that causes and perpetuates inflammation in serious diseases. It has 'adhesive'-like properties causing aggregation of blood cells and platelets, and can stick permanently within arterial tissue where it can contribute to further complications including thrombosis, linking it potentially to atherosclerosis and subsequent acute coronary events. In this mini review, we discuss briefly the implications and the potential value of measuring and manipulating it for clinical diagnostics and therapeutic purposes.

Revisiting the clinical usefulness of C-reactive protein in the set of cancer cachexia

Cancer cachexia is a highly complex multifactorial disorder that is often misdiagnosed, leading to suboptimal health outcomes. Indeed, cachexia is a concern in cancer, typifying lower response to treatment and risk of death. Thus, efforts have been made to better understand the molecular basis of this syndrome, envisioning to improve its diagnosis and management.

C-reactive protein (CRP) has been reported to be consistently increased in the circulation of patients with body wasting associated to chronic diseases. However, the role of CRP in the pathogenesis of cachexia remains elusive. Several hypotheses have been advanced but most of experimental findings support an indirect effect on the activation of muscle proteolysis, mostly through its interplay with pro-inflammatory cytokines. Herein, we overview the contribution of CRP to body wasting and its putative biomarker value for the diagnosis and follow-up of the therapeutic management of cachexia.

The plasma level of mCRP is linked to cardiovascular disease in antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND

C-reactive protein (CRP) has two natural isomers: C-reactive protein pentamer (pCRP) and C-reactive protein monomer (mCRP). The levels of CRP are significantly elevated in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). mCRP not only activates the endothelial cells, platelets, leukocytes, and complements, but also has a proinflammatory structural subtype that can localize and deposit in inflammatory tissues. Thus, it regulates a variety of clinical diseases, such as ischemia/reperfusion (I/R) injury, Alzheimer's disease, age-related macular degeneration, and cardiovascular disease. We hypothesized that plasma mCRP levels are related to cardiovascular disease in AAV.

METHODS

In this cross-sectional study, 37 patients with AAV were assessed. Brain natriuretic peptide (BNP) and mCRP in plasma were assessed by enzyme-linked immunosorbent assay (ELISA). The acute ST-segment elevation myocardial infarction (STEMI) was diagnosed by coronary angiography, and the Gensini score calculated. Echocardiography evaluated the ejection fraction (EF%), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and left ventricular mass index (LVMI). Estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine, age, and gender.

RESULTS

The plasma level of mCRP in AAV was significantly higher than that in healthy volunteers (P < 0.001). Then, mCRP and CRP levels were compared with and without STEMI complications in AAV. The plasma level of mCRP was higher, but that of CRP was lower in STEMI. The plasma level of mCRP was correlated with Birmingham vasculitis activity score (BVAS), eGFR, BNP, EF%, LVEDV, LVESV, LVMI, and STEMI complications' Gensini score in AAV; however, CRP did not correlate with BNP, EF%, LVEDV, LVESV, LVMI, and Gensini score.

CONCLUSIONS

The plasma level of mCRP was related to cardiovascular diseases in AAV patients.

effects of azide-containing human CRP isoforms and oxLDL on U937-derived macrophage production of atherosclerosis-related cytokines

Atherosclerosis is an inflammatory chronic disease of the arterial wall. Monomeric (m) and pentameric (p) C-reactive protein (CRP) and oxidized low density lipoproteins (oxLDL) seem to affect the pattern of cytokine production by macrophages, thus playing an important role in atherogenesis. Azide, the commercial preservative of CRP, may influence its action in vitro. The present study aimed to determine the effects of both isoforms of azide-containing CRP (mCRP and pCRP) with and without oxLDL on cytokine production by U937-derived macrophages. U937 monocytes were cultured and differentiated into macrophages and treated with mCRP, pCRP, oxLDL and azide individually and in combination. ELISA were performed to measure the levels of interferon-γ (IFN-γ), interleukin (IL)-4, IL-6, IL-10 and tumor necrosis factor (TNF)-α in culture supernatants collected from U937-derived macrophages following their respective treatments. Most single and combined treatments, especially in triple combination, were able to downregulate the levels of IFN-γ and IL-6 compared with control untreated cells, whilst the combination of mCRP and pCRP increased IL-4 levels. Regarding IL-10, except for an increase induced by mCRP, no significant effect was caused by any treatment compared with the control. On the other hand, the levels of TNF-α were not significantly affected by any treatment except for a decreasing trend that was observed with mCRP/oxLDL treatment compared with control. By contrast, double azide caused a significant decrease in the levels of IFN-γ and IL-6. The results of the present study indicated that mCRP, pCRP, oxLD and possibly azide, individually or in different combinations, had the tendency to upregulate the expression of IL-4 and to downregulate that of the pro-atherogenic cytokines, IFN-γ and IL-6, suggesting that the intima microenvironment serves a crucial role in atherogenesis.

Selective Apheresis of C-Reactive Protein for Treatment of Indications with Elevated CRP Concentrations

Almost every kind of inflammation in the human body is accompanied by rising C-reactive protein (CRP) concentrations. This can include bacterial and viral infection, chronic inflammation and so-called sterile inflammation triggered by (internal) acute tissue injury. CRP is part of the ancient humoral immune response and secreted into the circulation by the liver upon respective stimuli. Its main immunological functions are the opsonization of biological particles (bacteria and dead or dying cells) for their clearance by macrophages and the activation of the classical complement pathway. This not only helps to eliminate pathogens and dead cells, which is very useful in any case, but unfortunately also to remove only slightly damaged or inactive human cells that may potentially regenerate with more CRP-free time. CRP action severely aggravates the extent of tissue damage during the acute phase response after an acute injury and therefore negatively affects clinical outcome. CRP is therefore a promising therapeutic target to rescue energy-deprived tissue either caused by ischemic injury (e.g., myocardial infarction and stroke) or by an overcompensating immune reaction occurring in acute inflammation (e.g., pancreatitis) or systemic inflammatory response syndrome (SIRS; e.g., after transplantation or surgery). Selective CRP apheresis can remove circulating CRP safely and efficiently. We explain the pathophysiological reasoning behind therapeutic CRP apheresis and summarize the broad span of indications in which its application could be beneficial with a focus on ischemic stroke as well as the results of this therapeutic approach after myocardial infarction.

How C-Reactive Protein Structural Isoforms With Distinctive Bioactivities Affect Disease Progression

C-reactive protein (CRP) is a widely known, hepatically synthesized protein whose blood levels change rapidly and pronouncedly in response to any tissue damaging event associated with an inflammatory response. The synthesis and secretion of CRP is stimulated by interleukin-6, an early pleiotropic cytokine released by macrophages, endothelial, and other cells that are activated when localized normal tissue structures are compromised by trauma or disease. Serum CRP levels can change rapidly and robustly from 10-100-fold within 6–72 h of any tissue damaging event. Elevated blood levels correlate with the onset and extent of both activated inflammation and the acute phase biochemical response to the tissue insult. Because its functional bioactivity as the prototypic acute phase reactant has eluded clear definition for decades, diagnosticians of various conditions and diseases use CRP blood levels as a simple index for ongoing inflammation. In many pathologies, which involves many different tissues, stages of disease, treatments, and responses to treatments, its interpretive diagnostic value requires a deeper understanding of the localized tissue processes and events that contribute signals which regulate protective or pathological host defense bioactivities. This report presents concepts that describe how local tissue activation events can lead to a non-proteolytic, conformational rearrangement of CRP into a unique isoform with distinctive solubility, antigenicity, binding reactivities and bioactivities from that protein widely known and measured in serum. By describing factors that control the expression, tissue localization, half-life and pro-inflammatory amplification activity of this CRP isoform, a unifying explanation for the diagnostic significance of CRP measurement in disease is advanced.

Combined C-Reactive Protein and Novel Inflammatory Parameters as a Predictor in Cancer-What Can We Learn from the Hematological Experience?

The acute phase reaction is a systemic response to acute or chronic inflammation. The serum level of C-reactive protein (CRP) is the only acute phase biomarker widely used in routine clinical practice, including its uses for prognostics and therapy monitoring in cancer patients. Although Interleukin 6 (IL6) is a main trigger of the acute phase reactions, a series of acute phase reactants can contribute (e.g., other members in IL6 family or IL1 subfamily, and tumor necrosis factor α). However, the experience from patients receiving intensive chemotherapy for hematological malignancies has shown that, besides CRP, other biomarkers (e.g., cytokines, soluble cytokine receptors, soluble adhesion molecules) also have altered systemic levels as a part of the acute phase reaction in these immunocompromised patients. Furthermore, CRP and white blood cell counts can serve as a dual prognostic predictor in solid tumors and hematological malignancies. Recent studies also suggest that biomarker profiles as well as alternative inflammatory mediators should be further developed to optimize the predictive utility in cancer patients. Finally, the experience from allogeneic stem cell transplantation suggests that selected acute phase reactants together with specific markers of organ damages are useful for predicting or diagnosing graft versus host disease. Acute phase proteins may also be useful to identify patients (at risk of) developing severe immune-mediated toxicity after anticancer immunotherapy. To conclude, future studies of acute phase predictors in human malignancies should not only investigate the conventional inflammatory mediators (e.g., CRP, white blood cell counts) but also combinations of novel inflammatory parameters with specific markers of organ damages.

Functionality of C-Reactive Protein for Atheroprotection

C-reactive protein (CRP) is a pentameric molecule made up of identical monomers. CRP can be seen in three different forms: native pentameric CRP (native CRP), non-native pentameric CRP (non-native CRP), and monomeric CRP (mCRP). Both native and non-native CRP execute ligand-recognition functions for host defense. The fate of any pentameric CRP after binding to a ligand is dissociation into ligand-bound mCRP. If ligand-bound mCRP is proinflammatory, like free mCRP has been shown to be in vitro, then mCRP along with the bound ligand must be cleared from the site of inflammation. Once pentameric CRP is bound to atherogenic low-density lipoprotein (LDL), it reduces both formation of foam cells and proinflammatory effects of atherogenic LDL. A CRP mutant, that is non-native CRP, which readily binds to atherogenic LDL, has been found to be atheroprotective in a murine model of atherosclerosis. Thus, unlike statins, a drug that can lower only cholesterol levels but not CRP levels should be developed. Since non-native CRP has been shown to bind to all kinds of malformed proteins in general, it is possible that non-native CRP would be protective against all inflammatory states in which host proteins become pathogenic. If it is proven through experimentation employing transgenic mice that non-native CRP is beneficial for the host, then using a small-molecule compound to target CRP with the goal of changing the conformation of endogenous native CRP would be preferred over using recombinant non-native CRP as a biologic to treat diseases caused by pathogenic proteins such as oxidized LDL.

Regulation of C-reactive protein conformation in inflammation

C-reactive protein (CRP) is a non-specific diagnostic marker of inflammation and an evolutionarily conserved protein with roles in innate immune signaling. Natural CRP is composed of five identical globular subunits that form a pentamer, but the role of pentameric CRP (pCRP) during inflammatory pathogenesis remains controversial. Emerging evidence suggests that pCRP can be dissociated into monomeric CRP (mCRP) that has major roles in host defenses and inflammation. Here, we discuss our current knowledge of the dissociation mechanisms of pCRP and summarize the stepwise conformational transition model to mCRP to elucidate how CRP dissociation contributes to proinflammatory activity. These discussions will evoke new understanding of this ancient protein.

Hydroxycholesterol binds and enhances the anti-viral activities of zebrafish monomeric c-reactive protein isoforms

C-reactive proteins (CRPs) are among the faster acute-phase inflammation-responses proteins encoded by one gene (hcrp) in humans and seven genes (crp1-7) in zebrafish (Danio rerio) with importance in bacterial and viral infections. In this study, we described novel preferential bindings of 25-hydroxycholesterol (25HOCh) to CRP1-7 compared with other lipids and explored the antiviral effects of both 25HOCh and CRP1-7 against spring viremia carp virus (SVCV) infection in zebrafish. Both in silico and in vitro results confirmed the antiviral effect of 25HOCh and CRP1-7 interactions, thereby showing that the crosstalk between them differed among the zebrafish isoforms. The presence of oxidized cholesterols in human atherosclerotic plaques amplifies the importance that similar interactions may occur for vascular and/or neurodegenerative diseases during viral infections. In this context, the zebrafish model offers a genetic tool to further investigate these interactions.