Transitional changes in the CRP structure lead to the exposure of proinflammatory binding sites

C-reactive protein orchestrates acute allograft rejection in vascularized composite allotransplantation via subset-selective monocyte activation

INTRODUCTION

Despite recent substantial progress in vascularized composite allotransplantation (VCA), such as face transplantations, short- and long-term allograft survival is severely limited by allograft rejection. The acute-phase response, directly after allogeneic transplantation, represents an immune-inflammatory reaction to ischemia/reperfusion and acts as an early initiator of graft rejection. Acute-phase reactants mediate this immune response via crosstalk with the mononuclear phagocyte system.

OBJECTIVE

C-reactive protein (CRP), a well-known marker of inflammation, has pro-inflammatory properties and aggravates ischemia/reperfusion injury. Thus, we investigated how CRP impacts acute allograft rejection.

METHODS

Based on clinical observations in facial VCAs, we applied a complex hindlimb transplantation model in rats to investigate whether CRP directly affects transplant rejection. We further analyzed subset-specific infiltration and tissue distribution of recipient-derived monocytes in the early phase of acute rejection and assessed their differential regulation by CRP using intravital imaging.

RESULTS

We demonstrate that CRP accelerates allograft rejection and reduces allograft survival via selectively activating non-classical monocytes. The therapeutic stabilization of CRP abrogates this activating effect on monocytes, consequently attenuating acute allograft rejection. Intravital imaging of graft-infiltrating, recipient-derived monocytes during the early phase of acute rejection confirmed their differential regulation by CRP and their crucial role in driving the early stage of graft rejection.

CONCLUSION

Differential activation of recipient-derived monocytes by CRP aggravates innate immune response and accelerates clinical allograft rejection Thus, therapeutic targeting of CRP represents a novel promising strategy for preventing acute allograft rejection and potentially reducing chronic allograft rejection.

Monomeric C-reactive protein is associated with severity and prognosis of decompensated hepatitis B cirrhosis

C-reactive protein (CRP) is an acute-phase protein produced by the liver in response to infection and during chronic inflammatory disorders. Systemic inflammation is a major driver of cirrhosis progression from the compensated to the decompensated stage. Previous studies have shown that pentameric CRP (pCRP) to be a weak predictor of disease severity and prognosis in patients with decompensated hepatitis B cirrhosis, with it being only helpful for identifying patients with a higher short-term risk of death under certain conditions. Accumulating evidence indicates that pCRP dissociates to and acts primarily as the monomeric conformation (mCRP) at inflammatory loci, suggesting that mCRP may be a potentially superior disease marker with higher specificity and relevance to pathogenesis. However, it is unknown whether mCRP and anti-mCRP autoantibodies are associated with disease severity, or progression in decompensated hepatitis B cirrhosis. In this study, we evaluated the serum levels of mCRP and anti-mCRP autoantibodies in patients with decompensated cirrhosis of hepatitis B and their association with disease severity and theoretical prognosis. The results showed that patients with high mCRP and anti-mCRP autoantibody levels had more severe liver damage and that coagulation function was worse in patients with high anti-mCRP autoantibodies. Analysis of the correlation between pCRP, mCRP and anti-mCRP autoantibody levels with Model for End-Stage Liver Disease (MELD), Albumin-Bilirubin (ALBI), and Child-Turcotte-Pugh (CTP) prognostic scores showed that mCRP was the most strongly correlated with MELD score, followed by anti-mCRP autoantibodies; conversely, pCRP was not significantly correlated with prognostic score. Therefore, mCRP and anti-mCRP autoantibodies may be more advantageous clinical indicators than pCRP for evaluating the pathological state of decompensated hepatitis B cirrhosis.

Venous thromboembolism: diagnostic advances and unaddressed challenges in management

PURPOSE OF REVIEW

This review summarizes recent advances in developing targeted diagnostics for venous thromboembolism (VTE) and unaddressed knowledge gaps in patient management. Without addressing these critical data needs, the morbidity in VTE patients will persist.

RECENT FINDINGS

Recent studies investigating plasma protein profiles in VTE patients have identified key diagnostic targets to address the currently unmet need for low-cost, confirmatory, point-of-care VTE diagnostics. These studies and a growing body of evidence from animal model studies have revealed the importance of inflammatory and vascular pathology in driving VTE, which are currently unaddressed targets for VTE therapy. To enhance the translation of preclinical animal studies, clinical quantification of thrombus burden and comparative component analyses between modeled VTE and clinical VTE are necessary.

SUMMARY

Lead candidates from protein profiling of VTE patients' plasma offer a promising outlook in developing low cost, confirmatory, point-of-care testing for VTE. Additionally, addressing the critical knowledge gap of quantitatively measuring clinical thrombi will allow for an array of benefits in VTE management and informing the translatability of experimental therapeutics.

Diet-Induced Early Inflammatory Response of Visceral Adipose Tissue in Healthy Male Wistar Rats

The prolonged consumption of a high-fat diet (HFD) leads to abnormal growth of the visceral adipose tissue (VAT), increased macrophage infiltration, and altered secretion of biologically active molecules. This is considered as a precondition for the development of obesity, inflammation, and obesity-related disorders. Therefore, we studied HFD-induced changes in the tissue levels of the inflammatory markers C-reactive protein, serum amyloid-A, and interleukin-4 in healthy male Wistar rats. The animals were first divided at random into two groups subjected to either a standard or a high-fat diet. The initial effect of the diet was evaluated after fourteen weeks. In order to study the diet duration effect, the standard diet was given to twelve animals from the HFD group, while the remaining continued with the HFD for an additional four weeks. Our results showed that the HFD barely affected body mass index, conicity, relative fat mass, and Lee indices, whereas it provoked adipocyte hypertrophy and gradually increased the levels of both the pro- and anti-inflammatory markers. The switch from the high-fat to the standard diet resulted in the comparatively fast restoration of the baseline levels of the studied molecules. Although, the prolonged consumption of an HFD causes adipocyte hypertrophy in healthy male animals, the inflammatory process in VAT is well-coordinated, time-dependent, and reversible.

C-reactive protein lowers the serum level of IL-17, but not TNF-α, and decreases the incidence of collagen-induced arthritis in mice

The biosynthesis of C-reactive protein (CRP) in the liver is increased in inflammatory diseases including rheumatoid arthritis. Previously published data suggest a protective function of CRP in arthritis; however, the mechanism of action of CRP remains undefined. The aim of this study was to evaluate the effects of human CRP on the development of collagen-induced arthritis (CIA) in mice which is an animal model of autoimmune inflammatory arthritis. Two CRP species were employed: wild-type CRP which binds to aggregated IgG at acidic pH and a CRP mutant which binds to aggregated IgG at physiological pH. Ten CRP injections were given on alternate days during the development of CIA. Both wild-type and mutant CRP reduced the incidence of CIA, that is, reduced the number of mice developing CIA; however, CRP did not affect the severity of the disease in arthritic mice. The serum levels of IL-17, IL-6, TNF-α, IL-10, IL-2 and IL-1β were measured: both wild-type and mutant CRP decreased the level of IL-17 and IL-6 but not of TNF-α, IL-10, IL-2 and IL-1β. These data suggest that CRP recognizes and binds to immune complexes, although it was not clear whether CRP functioned in its native pentameric or in its structurally altered pentameric form in the CIA model. Consequently, ligand-complexed CRP, through an as-yet undefined mechanism, directly or indirectly, inhibits the production of IL-17 and eventually protects against the initiation of the development of arthritis. The data also suggest that IL-17, not TNF-α, is critical for the development of autoimmune inflammatory arthritis.

Platelet, Antiplatelet Therapy and Metabolic Dysfunction-Associated Steatotic Liver Disease: A Narrative Review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is not only related to traditional cardiovascular risk factors like type 2 diabetes mellitus and obesity, but it is also an independent risk factor for the development of cardiovascular disease. MASLD has been shown to be independently related to endothelial dysfunction and atherosclerosis. MASLD is characterized by a chronic proinflammatory response that, in turn, may induce a prothrombotic state. Several mechanisms such as endothelial and platelet dysfunction, changes in the coagulative factors, lower fibrinolytic activity can contribute to induce the prothrombotic state. Platelets are players and addresses of metabolic dysregulation; obesity and insulin resistance are related to platelet hyperactivation. Furthermore, platelets can exert a direct effect on liver cells, particularly through the release of mediators from granules. Growing data in literature support the use of antiplatelet agent as a treatment for MASLD. The use of antiplatelets drugs seems to exert beneficial effects on hepatocellular carcinoma prevention in patients with MASLD, since platelets contribute to fibrosis progression and cancer development. This review aims to summarize the main data on the role of platelets in the pathogenesis of MASLD and its main complications such as cardiovascular events and the development of liver fibrosis. Furthermore, we will examine the role of antiplatelet therapy not only in the prevention and treatment of cardiovascular events but also as a possible anti-fibrotic and anti-tumor agent.

C-reactive protein-complement factor H axis as a biomarker of activity in early and intermediate age-related macular degeneration

Purpose

To determine and compare the serum levels of complement Factor H (FH), monomeric C-Reactive Protein (mCRP) and pentameric C-Reactive protein (pCRP) in patients with age-related macular degeneration (AMD) and to correlate them with clinical, structural and functional parameters.

Methods

Cross-sectional observational study. One hundred thirty-nine individuals (88 patients and 51 healthy controls) from two referral centers were included and classified into three groups: early or intermediate AMD (n=33), advanced AMD (n=55), and age and sex matched healthy controls (n=51). Serum levels of FH, mCRP, and pCRP were determined and correlated with clinical and imaging parameters.

Results

Patients with intermediate AMD presented FH levels significantly lower than controls [186.5 (72.1-931.8) µg/mL vs 415.2 (106.1-1962.2) µg/mL; p=0.039] and FH levels <200 µg/mL were associated with the presence of drusen and pigmentary changes in the fundoscopy (p=0.002). While no differences were observed in pCRP and mCRP levels, and mCRP was only detected in less than 15% of the included participants, women had a significantly higher detection rate of mCRP than men (21.0% vs. 3.8%, p=0.045). In addition, the ratio mCRP/FH (log) was significantly lower in the control group compared to intermediate AMD (p=0.031). Visual acuity (p<0.001), macular volume (p<0.001), and foveal thickness (p=0.034) were significantly lower in the advanced AMD group, and choroidal thickness was significantly lower in advanced AMD compared to early/intermediate AMD (p=0.023).

Conclusion

Intermediate AMD was associated in our cohort with decreased serum FH levels together with increased serum mCRP/FH ratio. All these objective serum biomarkers may suggest an underlying systemic inflammatory process in early/intermediate AMD patients.

Reduced C-reactive protein levels after root canal treatment in clinically healthy young apical periodontitis individuals at cardiovascular risk. A prospective study

AIM

To determine the systemic inflammatory burden, including hsCRP and its monomeric forms, in patients with apical lesions of endodontic origin treated with root canal treatment (RCT).

METHODOLOGY

Prospective pre-/post-study. Apical periodontitis (AP) individuals aged 16-40 were included (N = 29). Individuals received RCT and were followed at 1 and 6 months. Fasting blood samples were obtained. Apical lesions of endodontic origin (ALEO) diameter (mm), and periapical index (PAI), were recorded. The serum concentrations of total hsCRP were determined by turbidimetry. Tumour necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, IL-1β, and soluble (s) E-selectin were assessed by Multiplex assay. Additionally, mCRP forms were determined in the serum of AP patients with a baseline moderate to high cardiovascular risk based on hsCRP stratification (hsCRP ≥1 mg/L) by immunowestern blot (n = 15). Also, CRP isoforms were explored in ALEOs from AP individuals (n = 4). Data were analysed with StataV16.

RESULTS

Periapical index and ALEO sizes were reduced at both follow-up visits after RCT (p < .05). Serum levels of TNF-α, IL-6, IL-10, IL-1β, and sE-selectin did not show significant differences. CRP was borderline reduced at 1 month (p = .04); however, in AP individuals at cardiovascular risk (hsCRP ≥ 1 mg/L), hsCRP and its monomeric isoform significantly decreased at 1 and 6 months (p < .05).

CONCLUSIONS

High-sensitivity CRP and mCRP are reduced after RCT in AP individuals at cardiovascular risk.

A One Step Strategy Based on Hollow Gold Nanoparticles to Detect C-Reactive Protein with High Sensitivity (Hs-CRP) in Serum for Monitoring Cardiovascular Disease

Purpose

Rapid detection and diagnosis of diseases facilitate timely and effective treatment of cardiovascular diseases (CVD). The establishment of a one-step rapid detection method provides a new method for the initial screening and disease risk assessment of patients with cardiovascular diseases in primary medical units.

Methods

Hollow gold nanoparticles (HGNPs) were synthesized using a cobalt template method followed by use as signal amplification probes for ultra-sensitive quantitative detection of serum C-reactive protein (CRP). To induce the localized surface plasmon resonance (LSPR) and improve protein labeling efficiency, we developed a sensitive detection mode by coating polyvinylpyrrolidone (PVP-K30) on the HGNPs, resulting in a significant improvement in detection performance.

Results

Compared to traditional colloidal GNP-based LFTA, PVP-coated HGNPs exhibit a lower visual detection limit of 1 ng/mL, which a 25-fold decrement compare to using GNPs as the antibody-labeled probe, and the detection limit could be reduced to 0.14 ng/mL under the quantitative instrument.

Conclusion

The one-step method based on HGNP immunochromatographic strips modified with PVP established in this study can be used for the detection of CRP and hs-CRP in biological samples. The performance of the immunochromatographic technique designed in this study was evaluated from the perspective of synthetic markers, and the application conditions of this strip were screened, verifying its high specificity, indicating that it has high sensitivity and strong detection limit compared to colloidal gold. The sensitivity of the hollow gold immunochromatographic test strip in this article has been increased by about 25 times, providing a new method for rapid detection of CVD in clinical diagnosis.

The Relationship between Complements and Age-Related Macular Degeneration and Its Pathogenesis

Age-related macular degeneration is a retinal disease that causes permanent loss of central vision in people over the age of 65. Its pathogenesis may be related to mitochondrial dysfunction, inflammation, apoptosis, autophagy, complement, intestinal flora, and lipid disorders. In addition, the patient's genes, age, gender, cardiovascular disease, unhealthy diet, and living habits may also be risk factors for this disease. Complement proteins are widely distributed in serum and tissue fluid. In the early 21st century, a connection was found between the complement cascade and age-related macular degeneration. However, little is known about the effect of complement factors on the pathogenesis of age-related macular degeneration. This article reviews the factors associated with age-related macular degeneration, the relationship between each factor and complement, the related functions, and variants and provides new ideas for the treatment of this disease.

Complement-pentraxins synergy: Navigating the immune battlefield and beyond

The complement is a crucial immune defense system that triggers rapid immune responses and offers efficient protection against foreign invaders and unwanted host elements, acting as a sentinel. Activation of the complement system occurs upon the recognition of pathogenic microorganisms or altered self-cells by pattern-recognition molecules (PRMs) such as C1q, collectins, ficolins, and pentraxins. Recent accumulating evidence shows that pentraxins establish a cooperative network with different classes of effector PRMs, resulting in synergistic effects in complement activation. This review describes the complex interaction of pentraxins with the complement system and the implications of this cooperative network for effective host defense during pathogen invasion.

Pentraxins in invertebrates and vertebrates: From structure, function and evolution to clinical applications

The immune system is divided into two broad categories, consisting of innate and adaptive immunity. As recognition and effector factors of innate immunity and regulators of adaptive immune responses, lectins are considered to be important defense chemicals against microbial pathogens, cell trafficking, immune regulation, and prevention of autoimmunity. Pentraxins, important members of animal lectins, play a significant role in protecting the body from pathogen infection and regulating inflammatory reactions. They can recognize and bind to a variety of ligands, including carbohydrates, lipids, proteins, nucleic acids and their complexes, and protect the host from pathogen invasion by activating the complement cascade and Fcγ receptor pathways. Based on the primary structure of the subunit, pentraxins are divided into short and long pentraxins. The short pentraxins are comprised of C-reactive protein (CRP) and serum amyloid P (SAP), and the most important member of the long pentraxins is pentraxin 3 (PTX3). The CRP and SAP exist in both vertebrates and invertebrates, while the PTX3 may be present only in vertebrates. The major ligands and functions of CRP, SAP and PTX3 and three activation pathways involved in the complement system are summarized in this review. Their different characteristics in various animals including humans, and their evolutionary trees are analyzed. The clinical applications of CRP, SAP and PTX3 in human are reviewed. Some questions that remain to be understood are also highlighted.

Expression of Tissue Factor and Platelet/Leukocyte Markers on Extracellular Vesicles Reflect Platelet-Leukocyte Interaction in Severe COVID-19

Severe COVID-19 is frequently associated with thromboembolic complications. Increased platelet activation and platelet-leukocyte aggregate formation can amplify thrombotic responses by inducing tissue factor (TF) expression on leukocytes. Here, we characterized TF-positive extracellular vesicles (EVs) and their cellular origin in 12 patients suffering from severe COVID-19 (time course, 134 samples overall) and 25 healthy controls. EVs exposing phosphatidylserine (PS) were characterized by flow cytometry. Their cellular origin was determined by staining with anti-CD41, anti-CD45, anti-CD235a, and anti-CD105 as platelet, leukocyte, red blood cell, and endothelial markers. We further investigated the association of EVs with TF, platelet factor 4 (PF4), C-reactive protein (CRP), and high mobility group box-1 protein (HMGB-1). COVID-19 patients showed higher levels of PS-exposing EVs compared to controls. The majority of these EVs originated from platelets. A higher amount of EVs in patient samples was associated with CRP, HMGB-1, PF4, and TF as compared to EVs from healthy donors. In COVID-19 samples, 16.5% of all CD41+ EVs displayed the leukocyte marker CD45, and 55.5% of all EV aggregates (CD41+CD45+) co-expressed TF, which reflects the interaction of platelets and leukocytes in COVID-19 on an EV level.

Association of mTOR Pathway and Conformational Alterations in C-Reactive Protein in Neurodegenerative Diseases and Infections

Inflammatory biomarkers have been very useful in detecting and monitoring inflammatory processes along with providing helpful information to select appropriate therapeutic strategies. C-reactive protein (CRP) is a nonspecific, but quite useful medical acute inflammatory biomarker and is associated with persistent chronic inflammatory processes. Several studies suggest that different levels of CRP are correlated with neurological disorders such as Alzheimer's disease (AD). However, dynamics of CRP levels have also been observed in virus/bacterial-related infections leading to inflammatory responses and this triggers mTOR-mediated pathways for neurodegeneration diseases. The biophysical structural transition from CRP to monomeric CRP (mCRP) and the significance of the ratio of CRP levels on the onset of symptoms associated with inflammatory response have been discussed. In addition, mTOR inhibitors act as immunomodulators by downregulating the expression of viral infection and can be explored as a potential therapy for neurological diseases.

Atherosclerosis and Its Related Laboratory Biomarkers

Atherosclerosis constitutes a persistent inflammatory ailment, serving as the predominant underlying condition for coronary artery disease (CAD), peripheral artery disease (PAD), and cerebrovascular disease. The progressive buildup of plaques within the walls of medium- and large-caliber arteries characterizes the atherosclerotic process. This accumulation results in significant narrowing that impedes blood flow, leading to critical tissue oxygen deficiency. Spontaneous blockage of thrombotic vessels can precipitate stroke and myocardial infarction, which are complications representing the primary global causes of mortality. Present-day models for predicting cardiovascular risk incorporate conventional risk factors to gauge the likelihood of cardiovascular events over a ten-year span. In recent times, researchers have identified serum biomarkers associated with an elevated risk of atherosclerotic events. Many of these biomarkers, whether used individually or in combination, have been integrated into risk prediction models to assess whether their inclusion enhances predictive accuracy. In this review, we have conducted a comprehensive analysis of the most recently published literature concerning serum biomarkers associated with atherosclerosis. We have explored the potential utility of incorporating these markers in guiding clinical decisions.

The Potential Role of C-Reactive Protein in Metabolic-Dysfunction-Associated Fatty Liver Disease and Aging

Nonalcoholic fatty liver disease (NAFLD), recently redefined as metabolic-dysfunction-associated fatty liver disease (MASLD), is liver-metabolism-associated steatohepatitis caused by nonalcoholic factors. NAFLD/MASLD is currently the most prevalent liver disease in the world, affecting one-fourth of the global population, and its prevalence increases with age. Current treatments are limited; one important reason hindering drug development is the insufficient understanding of the onset and pathogenesis of NAFLD/MASLD. C-reactive protein (CRP), a marker of inflammation, has been linked to NAFLD and aging in recent studies. As a conserved acute-phase protein, CRP is widely characterized for its host defense functions, but the link between CRP and NAFLD/MASLD remains unclear. Herein, we discuss the currently available evidence for the involvement of CRP in MASLD to identify areas where further research is needed. We hope this review can provide new insights into the development of aging-associated NAFLD biomarkers and suggest that modulation of CRP signaling is a potential therapeutic target.

The Role of Anti-mCRP Autoantibodies in Lupus Nephritis

Background

Lupus nephritis is characterized by multiple autoantibodies production. However, there are few autoantibodies associated with disease activity and prognosis. CRP exists in at least two conformationally distinct forms: native pentameric C-reactive protein (pCRP) and modified/monomeric CRP (mCRP). Autoantibodies against mCRP are prevalent in sera of patients with lupus nephritis and are reported to be pathogenic.

Summary

The levels of serum anti-mCRP autoantibodies are associated with clinical disease activity, tubulointerstitial lesions, treatment response, and prognosis in patients with lupus nephritis. The key epitope of mCRP was amino acid 35-47. Furthermore, emerging evidence indicated that anti-mCRP autoantibodies could participate in the pathogenesis of lupus nephritis by forming in situ immune complexes or interfering with the biological functions of mCRP, such as binding to complement C1q and factor H.

Key Messages

Here, we review the recent advances in the prevalence, clinical-pathological associations, and potential pathogenesis of anti-mCRP autoantibodies in lupus nephritis, which may provide a promising novel therapeutic strategy for lupus nephritis.

Serum CRP biomarker detection by using carbon nanotube field-effect transistor (CNT-FET) immunosensor

C-reactive protein (CRP) is produced by the liver in response to systemic inflammation caused by bacterial infection, trauma and internal organ failures. CRP serves as a potential biomarker in the precise diagnosis of cardiovascular risk, type-2 diabetes, metabolic syndrome, hypertension and various types of cancers. The pathogenic conditions indicated above are diagnosed by an elevated CRP level in the serum. In this study, we successfully fabricated a highly sensitive and selective carbon nanotube field-effect transistor (CNT-FET) immunosensor for the detection of CRP. The CNTs were deposited on the Si/SiO2 surface, between source-drain electrodes, afterwards modified with well-known linker PBASE and then anti-CRP was immobilized. This anti-CRP functionalized CNT-FET immunosensor exhibits a wide dynamic detection range (0.01-1000 μg/mL) CRP detection, rapid response time (2-3 min) and low variation (<3 %) which can be delivered as a low-cost and rapid clinical detection technology for the early diagnosis of coronary heart disease (CHD). For the clinical applications, our sensor was tested using CRP fortified serum samples and sensing performance was validated using enzyme-linked immune-sorbent assay (ELISA). This CNT-FET immunosensor will be helpful in taking over the complex laboratory-based expensive traditional CRP diagnostic procedures practiced in the hospitals.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

Self-Propelled Proteomotors with Active Cell-Free mtDNA Clearance for Enhanced Therapy of Sepsis-Associated Acute Lung Injury

Acute lung injury (ALI) is a frequent and serious complication of sepsis with limited therapeutic options. Gaining insights into the inflammatory dysregulation that causes sepsis-associated ALI can help develop new therapeutic strategies. Herein, the crucial role of cell-free mitochondrial DNA (cf-mtDNA) in the regulation of alveolar macrophage activation during sepsis-associated ALI is identified. Most importantly, a biocompatible hybrid protein nanomotor (NM) composed of recombinant deoxyribonuclease I (DNase-I) and human serum albumin (HSA) via glutaraldehyde-mediated crosslinking is prepared to obtain an inhalable nanotherapeutic platform targeting pulmonary cf-mtDNA clearance. The synthesized DNase-I/HSA NMs are endowed with self-propulsive capability and demonstrate superior performances in stability, DNA hydrolysis, and biosafety. Pulmonary delivery of DNase-I/HSA NMs effectively eliminates cf-mtDNAs in the lungs, and also improves sepsis survival by attenuating pulmonary inflammation and lung injury. Therefore, pulmonary cf-mtDNA clearance strategy using DNase-I/HSA NMs is considered to be an attractive approach for sepsis-associated ALI.

Impact of fixed orthodontic appliances on blood count and high-sensitivity C-reactive protein levels: A prospective cohort study

INTRODUCTION

The aim was to elucidate the magnitude of alterations in systemic blood counts in healthy patients during the first 14 days after fixed orthodontic appliance placement.

METHODS

This prospective cohort study consecutively included 35 White Caucasian patients starting orthodontic treatment with fixed appliances. The mean age was 24.48 ± 6.68 years. All patients were physically and periodontally healthy. Blood samples were collected at 3 time points: (1) baseline (exactly before the placement of appliances), (2) 5 days after bonding, and (3) 14 days after baseline. Whole blood and erythrocyte sedimentation rates were analyzed in automated hematology and erythrocyte sedimentation rate analyzer. Serum high-sensitivity C-reactive protein levels were measured by the nephelometric method. Standardized sample handling and patient preparation procedures were adopted to reduce preanalytical variability.

RESULTS

A total of 105 samples were analyzed. All clinical and orthodontic procedures were performed without complications or side effects during the study period. All laboratory procedures were performed per protocol. Significantly lower white blood cell counts were detected 5 days after bracket bonding, compared with baseline (P <0.05). Hemoglobin levels were lower at 14 days than baseline (P <0.05). No other significant shifts or alteration patterns were observed over time.

CONCLUSIONS

Orthodontic fixed appliances led to a limited and transient change in white blood cell counts and hemoglobin levels during the first days after bracket placement. The fluctuation of high-sensitivity C-reactive protein levels was not significant, demonstrating a lack of association between systemic inflammation and orthodontic treatment.

Being Eaten Alive: How Energy-Deprived Cells Are Disposed of, Mediated by C-Reactive Protein-Including a Treatment Option

In medicine, C-reactive protein (CRP) has become established primarily as a biomarker, predicting patient prognosis in many indications. Recently, however, there has been mounting evidence that it causes inflammatory injury. As early as 1999, CRP was shown to induce cell death after acute myocardial infarction (AMI) in rats and this was found to be dependent on complement. The pathological effect of CRP was subsequently confirmed in further animal species such as rabbit, mouse and pig. A conceptual gap was recently closed when it was demonstrated that ischemia in AMI or ischemia/hypoxia in the severe course of COVID-19 causes a drastic lack of energy in involved cells, resulting in an apoptotic presentation because these cells cannot repair/flip-flop altered lipids. The deprivation of energy leads to extensive expression on the cell membranes of the CRP ligand lysophosphatidylcholine. Upon attachment of CRP to this ligand, the classical complement pathway is triggered leading to the swift elimination of viable cells with the appearance of an apoptotic cell by phagocytes. They are being eaten alive. This, consequently, results in substantial fibrotic remodeling within the involved tissue. Inhibiting this pathomechanism via CRP-targeting therapy has been shown to be beneficial in different indications.

C-reactive protein: a target for therapy to reduce inflammation

C-reactive protein (CRP) is well-recognized as a sensitive biomarker of inflammation. Association of elevations in plasma/serum CRP level with disease state has received considerable attention, even though CRP is not a specific indicator of a single disease state. Circulating CRP levels have been monitored with a varying degree of success to gauge disease severity or to predict disease progression and outcome. Elevations in CRP level have been implicated as a useful marker to identify patients at risk for cardiovascular disease and certain cancers, and to guide therapy in a context-dependent manner. Since even strong associations do not establish causality, the pathogenic role of CRP has often been over-interpreted. CRP functions as an important modulator of host defense against bacterial infection, tissue injury and autoimmunity. CRP exists in conformationally distinct forms, which exhibit distinct functional properties and help explaining the diverse, often contradictory effects attributed to CRP. In particular, dissociation of native pentameric CRP into its subunits, monomeric CRP, unmasks "hidden" pro-inflammatory activities in pentameric CRP. Here, we review recent advances in CRP targeting strategies, therapeutic lowering of circulating CRP level and development of CRP antagonists, and a conformation change inhibitor in particular. We will also discuss their therapeutic potential in mitigating the deleterious actions attributed to CRP under various pathologies, including cardiovascular, pulmonary and autoimmune diseases and cancer.

Challenges associated with using extracellular vesicles as biomarkers in neurodegenerative disease

INTRODUCTION

The hunt for new biomarkers - for the diagnosis of subcategories of disease, or for the monitoring of the efficacy of novel therapeutics - is an increasingly relevant challenge in the current era of precision medicine. In neurodegenerative research, the aim is to look for simple tools which can predict cognitive or motor decline early, and to determine whether these can also be used to test the efficacy of new interventions. Extracellular vesicles (EVs) are thought to play an important role in intercellular communication and have been shown to play a vital role in a number of diseases.

AREAS COVERED

The aim of this review is to examine what we know about EVs in neurodegeneration and to discuss their potential to be diagnostic and prognostic biomarkers in the future. It will cover the techniques used to isolate and study EVs and what is currently known about their presence in neurodegenerative diseases. In particular, we will discuss what is required for standardization in biomarker research, and the challenges associated with using EVs within this framework.

EXPERT OPINION

The technical challenges associated with isolating EVs consistently, combined with the complex techniques required for their efficient analysis, might preclude 'pure' EV populations from being used as effective biomarkers. Whilst biomarker discovery is important for more effective diagnosis, monitoring, prediction and prognosis in neurodegenerative disease, reproducibility and ease-of-use should be the priorities.

Fueling the flames of colon cancer – does CRP play a direct pro-inflammatory role?

Background

Systemic inflammation, diagnostically ascribed by measuring serum levels of the acute phase reactant C-reactive protein (CRP), has consistently been correlated with poor outcomes across cancer types. CRP exists in two structurally and functionally distinct isoforms, circulating pentameric CRP (pCRP) and the highly pro-inflammatory monomeric isoform (mCRP). The aim of this pilot study was to map the pattern of mCRP distribution in a previously immunologically well-defined colon cancer (CC) cohort and explore possible functional roles of mCRP within the tumor microenvironment (TME).

Methods

Formalin-fixed, paraffin-embedded (FFPE) tissue samples from 43 stage II and III CC patients, including 20 patients with serum CRP 0-1 mg/L and 23 patients with serum CRP &gt;30 mg/L were immunohistochemically (IHC) stained with a conformation-specific mCRP antibody and selected immune and stromal markers. A digital analysis algorithm was developed for evaluating mCRP distribution within the primary tumors and adjacent normal colon mucosa.

Results

mCRP was abundantly present within tumors from patients with high serum CRP (&gt;30 mg/L) diagnostically interpreted as being systemically inflamed, whereas patients with CRP 0-1 mg/L exhibited only modest mCRP positivity (median mCRP per area 5.07‰ (95%CI:1.32-6.85) vs. 0.02‰ (95%CI:0.01-0.04), p&lt;0.001). Similarly, tissue-expressed mCRP correlated strongly with circulating pCRP (Spearman correlation 0.81, p&lt;0.001). Importantly, mCRP was detected exclusively within tumors, whereas adjacent normal colon mucosa showed no mCRP expression. Double IHC staining revealed colocalization of mCRP with endothelial cells and neutrophils. Intriguingly, some tumor cells also colocalized with mCRP, suggesting a direct interaction or mCRP expression by the tumor itself.

Conclusion

Our data show that the pro-inflammatory mCRP isoform is expressed in the TME of CC, primarily in patients with high systemic pCRP values. This strengthens the hypothesis that CRP might not only be an inflammatory marker but also an active mediator within tumors.

Venous thromboembolism in viral diseases: A comprehensive literature review

Venous thromboembolism (VTE) is known to be a common respiratory and/or cardiovascular complication in hospitalized patients with viral infections. Numerous studies have proven human immunodeficiency virus infection to be a prothrombotic condition. An elevated VTE risk has been observed in critically ill H1N1 influenza patients. VTE risk is remarkably higher in patients infected with the Hepatitis C virus in contrast to uninfected subjects. The elevation of D-dimer levels supported the association between Chikungunya and the Zika virus and the rise of clinical VTE risk. Varicella-zoster virus is a risk factor for both cellulitis and the consequent invasive bacterial disease which may take part in thrombotic initiation. Eventually, hospitalized patients infected with the coronavirus disease of 2019 (COVID-19), the cause of the ongoing worldwide pandemic, could mainly suffer from an anomalous risk of coagulation activation with enhanced venous thrombosis events and poor quality clinical course. Although the risk of VTE in nonhospitalized COVID-19 patients is not known yet, there are a large number of guidelines and studies on thromboprophylaxis administration for COVID-19 cases. This study aims to take a detailed look at the effect of viral diseases on VTE, the epidemiology of VTE in viral diseases, and the diagnosis and treatment of VTE.

Monomeric C-Reactive Protein in Atherosclerotic Cardiovascular Disease: Advances and Perspectives

This review aimed to trace the inflammatory pathway from the NLRP3 inflammasome to monomeric C-reactive protein (mCRP) in atherosclerotic cardiovascular disease. CRP is the final product of the interleukin (IL)-1β/IL-6/CRP axis. Its monomeric form can be produced at sites of local inflammation through the dissociation of pentameric CRP and, to some extent, local synthesis. mCRP has a distinct proinflammatory profile. In vitro and animal-model studies have suggested a role for mCRP in: platelet activation, adhesion, and aggregation; endothelial activation; leukocyte recruitment and polarization; foam-cell formation; and neovascularization. mCRP has been shown to deposit in atherosclerotic plaques and damaged tissues. In recent years, the first published papers have reported the development and application of mCRP assays. Principally, these studies demonstrated the feasibility of measuring mCRP levels. With recent advances in detection techniques and the introduction of first assays, mCRP-level measurement should become more accessible and widely used. To date, anti-inflammatory therapy in atherosclerosis has targeted the NLRP3 inflammasome and upstream links of the IL-1β/IL-6/CRP axis. Large clinical trials have provided sufficient evidence to support this strategy. However, few compounds target CRP. Studies on these agents are limited to animal models or small clinical trials.

Vascular injury is associated with repetitive head impacts and tau pathology in chronic traumatic encephalopathy

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease linked to repetitive head impacts (RHI) and characterized by perivascular hyperphosphorylated tau (p-tau) deposits. The role of vascular injury, blood-brain barrier leakage, and neuroinflammation in CTE pathogenesis is not well understood. We performed quantitative immunoassays for intercellular adhesion molecule 1 (ICAM1), vascular cellular adhesion molecule 1 (VCAM1), and C-reactive protein (CRP) within the postmortem dorsolateral frontal cortex of participants with and without a history of RHI and CTE (n = 156), and tested for associations with RHI, microgliosis, and tau pathology measures. Levels of vascular injury-associated markers ICAM1, VCAM1, and CRP were increased in CTE compared to RHI-exposed and -naïve controls. ICAM1 and CRP increased with RHI exposure duration (p < 0.01) and were associated with increased microglial density (p < 0.001) and tau pathology (AT8, p-tau396, p-tau202; p < 0.05). Histologically, there was significantly increased ICAM1 staining of the microvasculature, extracellular space, and astrocytes at the sulcal depths in high stage CTE compared to both low stage CTE and controls. Multifocal perivascular immunoreactivity for serum albumin was present in all RHI-exposed individuals. These findings demonstrate that vascular injury markers are associated with RHI exposure, duration, and microgliosis, are elevated in CTE, and increase with disease severity.

Usefulness of phase angle on bioelectrical impedance analysis as a surveillance tool for postoperative infection in critically ill patients

Purpose

Bioelectrical impedance analysis (BIA) has advantages of obtaining results quickly, safely, reproducibly, and non-invasively. Phase angle (PhA) is one of the parameter of BIA, its values represent the permeability or integrity of cell membrane. With the exception of C-reactive protein (CRP), few studies have estimated an association between PhA and these conventional biomarkers. Herein, we aimed to investigate the association between the PhA value and the conventional inflammatory markers in postoperative patients in intensive care unit (ICU). Also, the correlation between the change in PhA and the occurrence of infectious complication were determined.

Methods

From July 2020 to February 2022, retrospective observation study conducted in 221 patients who admitted to ICU after abdominal surgery. BIA measurements and blood sampling were routinely performed the next morning. The relationship between PhA and the inflammatory markers were assessed after adjusting for age and body mass index. Univariate and multivariate logistic regression analysis was performed to examine the predisposing factors for postoperative infections.

Results

Among 221 patients admitted to ICU after abdominal surgery, infectious complications occurred in 62 cases. CRP, procalcitonin, or presepsin levels were negatively correlated with PhA in both gender. (-0.295, -0.198 or -0.212 of partial correlation coefficients, respectively in males, and 0.313, -0.245 or -0.36 of partial correlation coefficients, respectively in females) But, white blood cell did not show significant association with PhA in both genders. For males, increased level of CRP on postoperative day 1 (POD1) was revealed as the significant predicting factor for postoperative infectious complication [odds ratio (OR): 1.184, 95% confidence interval (CI): 1.090-1.285, p < 0.001]. For females, increased Acute Physiology and Chronic Health Evaluation II score at admission (OR: 1.457, 95% CI: 1.068-1.987, p = 0.018), increased level of presepsin on (OR: 1.003, 95% CI: 1.001-1.006, p = 0.016) and decreased value of PhA on POD1 (OR: 0.980, 95% CI: 0.967-0.993, p = 0.003) were revealed as the significant predicting factors.

Conclusion

Phase angle obtained through BIA can be used as a predictor of infection as it shows a significant association with inflammatory markers. Phase angle measurements through BIA could improve patient prognosis after abdominal surgery through the careful observation of infections and early, appropriate treatment.

A pH-responsive T1-T2 dual-modal MRI contrast agent for cancer imaging

Magnetic resonance imaging (MRI) is a non-invasive imaging technology to diagnose health conditions, showing the weakness of low sensitivity. Herein, we synthesize a contrast agent, SPIO@SiO₂@MnO₂, which shows decreased T₁ and T₂ contrast intensity in normal physiological conditions. In the acid environment of tumor or inflamed tissue, the manganese dioxide (MnO₂) layer decomposes into magnetically active Mn²⁺ (T₁-weighted), and the T₁ and T₂ signals are sequentially recovered. In addition, both constrast quenching-activation degrees of T₁ and T₂ images can be accurately regulated by the silicon dioxide (SiO₂) intermediate layer between superparamagnetic iron oxide (SPIO) and MnO₂. Through the "dual-contrast enhanced subtraction" imaging processing technique, the contrast sensitivity of this MRI contrast agent is enhanced to a 12.3-time difference between diseased and normal tissue. Consequently, SPIO@SiO₂@MnO₂ is successfully applied to trace the tiny liver metastases of approximately 0.5 mm and monitor tissue inflammation.

A novel phosphocholine-mimetic inhibits a pro-inflammatory conformational change in C-reactive protein

C-reactive protein (CRP) is an early-stage acute phase protein and highly upregulated in response to inflammatory reactions. We recently identified a novel mechanism that leads to a conformational change from the native, functionally relatively inert, pentameric CRP (pCRP) structure to a pentameric CRP intermediate (pCRP*) and ultimately to the monomeric CRP (mCRP) form, both exhibiting highly pro-inflammatory effects. This transition in the inflammatory profile of CRP is mediated by binding of pCRP to activated/damaged cell membranes via exposed phosphocholine lipid head groups. We designed a tool compound as a low molecular weight CRP inhibitor using the structure of phosphocholine as a template. X-ray crystallography revealed specific binding to the phosphocholine binding pockets of pCRP. We provide in vitro and in vivo proof-of-concept data demonstrating that the low molecular weight tool compound inhibits CRP-driven exacerbation of local inflammatory responses, while potentially preserving pathogen-defense functions of CRP. The inhibition of the conformational change generating pro-inflammatory CRP isoforms via phosphocholine-mimicking compounds represents a promising, potentially broadly applicable anti-inflammatory therapy.

Role of Biomarkers in Periprosthetic Joint Infections

Periprosthetic joint infection (PJI) is one of the most serious complications after joint arthroplasty. The incidence rate of PJI after total joint replacement is 1-3%. Although there are different guidelines and diagnostic criteria used to diagnose PJI, diagnosing PJI is a highly difficult process for orthopedists. The current Musculoskeletal Infection Society (MSIS) criteria are widely used for the diagnosis of PJI. These criteria include results from blood/synovial fluid tests, physical examination, and histological and microbiological analyses of intra-operative samples. However, there is currently no blood or synovial test that can definitively diagnose PJI. To make a more effective diagnosis of PJI, a large number of studies have explored and continue to investigate biomarkers. This review aims to provide general information about serum and synovial markers used for the diagnosis of PJI that may be used to create a database to guide researchers in new studies.

Structurally Altered, Not Wild-Type, Pentameric C-Reactive Protein Inhibits Formation of Amyloid-β Fibrils

The structure of wild-type pentameric C-reactive protein (CRP) is stabilized by two calcium ions that are required for the binding of CRP to its ligand phosphocholine. CRP in its structurally altered pentameric conformations also binds to proteins that are denatured and aggregated by immobilization on microtiter plates; however, the identity of the ligand on immobilized proteins remains unknown. We tested the hypotheses that immobilization of proteins generated an amyloid-like structure and that amyloid-like structure was the ligand for structurally altered pentameric CRP. We found that the Abs to amyloid-β peptide 1-42 (Aβ) reacted with immobilized proteins, indicating that some immobilized proteins express an Aβ epitope. Accordingly, four different CRP mutants capable of binding to immobilized proteins were constructed, and their binding to fluid-phase Aβ was determined. All CRP mutants bound to fluid-phase Aβ, suggesting that Aβ is a ligand for structurally altered pentameric CRP. In addition, the interaction between CRP mutants and Aβ prevented the formation of Aβ fibrils. The growth of Aβ fibrils was also halted when CRP mutants were added to growing fibrils. Biochemical analyses of CRP mutants revealed altered topology of the Ca2+-binding site, suggesting a role of this region of CRP in binding to Aβ. Combined with previous reports that structurally altered pentameric CRP is generated in vivo, we conclude that CRP is a dual pattern recognition molecule and an antiamyloidogenic protein. These findings have implications for Alzheimer's and other neurodegenerative diseases caused by amyloidosis and for the diseases caused by the deposition of otherwise fluid-phase proteins.

C-reactive protein, immunothrombosis and venous thromboembolism

C-reactive protein (CRP) is a member of the highly conserved pentraxin superfamily of proteins and is often used in clinical practice as a marker of infection and inflammation. There is now increasing evidence that CRP is not only a marker of inflammation, but also that destabilized isoforms of CRP possess pro-inflammatory and pro-thrombotic properties. CRP circulates as a functionally inert pentameric form (pCRP), which relaxes its conformation to pCRP* after binding to phosphocholine-enriched membranes and then dissociates to monomeric CRP (mCRP). with the latter two being destabilized isoforms possessing highly pro-inflammatory features. pCRP* and mCRP have significant biological effects in regulating many of the aspects central to pathogenesis of atherothrombosis and venous thromboembolism (VTE), by directly activating platelets and triggering the classical complement pathway. Importantly, it is now well appreciated that VTE is a consequence of thromboinflammation. Accordingly, acute VTE is known to be associated with classical inflammatory responses and elevations of CRP, and indeed VTE risk is elevated in conditions associated with inflammation, such as inflammatory bowel disease, COVID-19 and sepsis. Although the clinical data regarding the utility of CRP as a biomarker in predicting VTE remains modest, and in some cases conflicting, the clinical utility of CRP appears to be improved in subsets of the population such as in predicting VTE recurrence, in cancer-associated thrombosis and in those with COVID-19. Therefore, given the known biological function of CRP in amplifying inflammation and tissue damage, this raises the prospect that CRP may play a role in promoting VTE formation in the context of concurrent inflammation. However, further investigation is required to unravel whether CRP plays a direct role in the pathogenesis of VTE, the utility of which will be in developing novel prophylactic or therapeutic strategies to target thromboinflammation.

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.

Regulation of Conformational Changes in C-reactive Protein Alters its Bioactivity

The acute phase C-reactive protein (CRP) is mainly synthesized and secreted by the liver in a cytokine-mediated response to infection or inflammation and circulates as a pentamer (pCRP) in plasma. Recent studies indicate that CRP is not only a marker but is directly involved in inflammation. CRP has a vital role in host defense and inflammation, metabolic function and scavenging through its ability for calcium depended binding to exogenous and endogenous molecules having phosphocholine followed by activation of the classical complement pathway. Accumulating evidence indicates that pCRP dissociates into monomeric CRP (mCRP) and most proinflammatory actions of CRP are only expressed following dissociation of its native pentameric assembly into mCRP. The dissociation of CRP into mCRP altogether promotes the ligand-binding capability. mCRP emerges to be the main conformation of CRP that participates in the regulation of local inflammation, however, little is identified concerning what triggers the significantly enhanced actions of mCRP and their binding to diverse ligands. The separation of mCRP from pCRP may be a direct relationship between CRP and inflammation. Here we review the current literature on CRP dissociation and its interaction with different ligands. The possibility to avoid the generation of the proinflammatory potential of mCRP has driven therapeutic approaches by targeting the dissociation mechanism of pCRP or inhibition of mCRP itself during inflammation.

Monomeric form of C-reactive protein in the assessment of the residual inflammatory cardiovascular risk in patients with subclinical carotid atherosclerosis

Aim      To study the relationship between monomeric C-reactive protein (mCRP) and the progression of asymptomatic carotid atherosclerosis in patients with a moderate risk for cardiovascular diseases (CVD) as assessed with the SCORE model.Material and methods  The study included 80 men and women aged 53.1±5.8 years assigned to the category of a moderate risk for CVDs by the SCORE model with a low-density lipoprotein cholesterol (LDL-C) level of 2.7-4.8 mmol/l and asymptomatic, hemodynamically insignificant (&lt;50% luminal narrowing) carotid atherosclerosis according to ultrasonic data. All patients were prescribed atorvastatin to achieve a LDL-C level &lt;2.6 mmol/l. After 7 years of follow-up, ultrasonic examination of carotid arteries was performed, and concentrations of high-sensitivity C-reactive protein (hsCRP) and mCRP were measured.Results A concentration of LDL-C &lt;2.6 mmol/l was achieved in all patients. The progression of atherosclerosis as determined by an increased number of atherosclerotic plaques (ASPs), was observed in 45 (56 %) patients. At 7 months of follow-up, concentrations of cCRP were higher in the group of patients with progressive carotid atherosclerosis, while the levels of hsCRP did not differ between the groups. Increased mCRP concentrations were associated with changes in variables of the "atherosclerotic load", including the number of ASPs, total ASP height, and the intima-media thickness (IMT). In patients with a median mCRP concentration of 5.2 [3.3; 7.1] µg/l and more, the increases in mean ACP number and total ASP height were considerably higher than in patients with mCRP concentrations lower than the median (3.9 and 2.7 times, respectively), whereas the odds ratio for the progression of asymptomatic carotid atherosclerosis was 5.5 (95 % confidence interval, CI: 2.1-14.6; p=0.001). ROC analysis showed that the concentration of hsCRP had no predictive value for prognosis of asymptomatic carotid atherosclerosis (p=0.16), while the area under the ROC curve (AUC) for mCRP was 0.75±0.056 (95 % CI: 0.64-0.86; p=0.001).Conclusion      According to the results of 7-year follow-up, the plasma concentration of mCRP was significantly higher in patients with an increased number of ASPs than in patients without this increase. An increased level of mCRP may indicate a higher inflammatory risk of CVD.

The monomeric C-reactive protein level is associated with the increase in carotid plaque number in patients with subclinical carotid atherosclerosis

The high-sensitivity C-reactive protein (hsCRP) assay measures the level of the pentameric form of CRP in blood. Currently, there are no available assays measuring the level of the monomeric form of CRP (mCRP), produced at sites of local inflammation. We developed an assay measuring the mCRP level in blood plasma with functional beads for flow cytometry. The assay was used to measure the mCRP level in 80 middle-aged individuals with initially moderate cardiovascular SCORE risk. By the time of the mCRP measurement, the patients have been followed up for subclinical carotid atherosclerosis progression for 7 years. Ultrasound markers of subclinical atherosclerosis, which included plaque number (PN) and total plaque height (PH), were measured at baseline and at the 7th-year follow-up survey. Inflammatory biomarkers, including mCRP, hsCRP, inteleukin-6 (IL-6) and von Willebrand factor (VWF) level, were measured at the 7th-year follow-up survey. The median level of mCRP was 5.2 (3.3; 7.1) μg/L, hsCRP 1.05 (0.7; 2.1) mg/L, IL-6 0.0 (0.0; 2.8) pg/mL, VWF 106 (77; 151) IU/dL. In the patients with the mCRP level below median vs. the patients with the median mCRP level or higher, change from baseline in PN was 0.0 (0.0; 1.0) vs. 1.0 (1.0; 2.0) and PH 0.22 (−0.24; 1.91) mm vs. 1.97 (1.14; 3.14) mm, respectively (p < 0.05). The adjusted odds ratio for the formation of new carotid atherosclerotic plaques was 4.7 (95% CI 1.7; 13.2) for the patients with the median mCRP level or higher. The higher mCRP level is associated with the more pronounced increase in PN and PH in patients with normal level of traditional inflammatory biomarkers and initially moderate cardiovascular SCORE risk.

The Cholesterol-Binding Sequence in Monomeric C-Reactive Protein Binds to the SARS-CoV-2 Spike Receptor-Binding Domain and Blocks Interaction With Angiotensin-Converting Enzyme 2

The receptor-binding domain (RBD) of the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to the human angiotensin-converting enzyme 2 (ACE2) receptor, which is a prerequisite for the virus to enter the cell. C-reactive protein (CRP) is an important marker of inflammation and is a putative soluble pattern recognition receptor. Clinical elevation of CRP levels in patients with COVID-19 is one of the characteristics of the disease; however, whether CRP is involved in COVID-19 pathogenesis is unknown. Here, we report that monomeric CRP (mCRP) can bind to the SARS-CoV-2 spike RBD and competitively inhibit its binding to ACE2. Furthermore, truncated mutant peptide competition assays and surface plasmon resonance binding experiments showed that the cholesterol-binding sequence (CBS, amino acids 35-47) in mCRP was critical for mediating the binding of mCRP to spike RBD. In a cell model of spike RBD and ACE2 interaction, the CBS motif effectively reduced the binding of spike RBD to ACE2 overexpressed on the cell surface. Thus, this study highlights the pattern recognition function of mCRP in innate immunity and provides a preliminary theoretical basis for the development of the CBS motif in mCRP into a functional peptide with both diagnostic significance and potential therapeutic capabilities.

Transitional changes in the structure of C-reactive protein create highly pro-inflammatory molecules: Therapeutic implications for cardiovascular diseases

C-reactive protein (CRP) is the prototypic acute-phase reactant that has long been recognized almost exclusively as a marker of inflammation and predictor of cardiovascular risk. However, accumulating evidence indicates that CRP is also a direct pathogenic pro-inflammatory mediator in atherosclerosis and cardiovascular diseases. The 'CRP system' consists of at least two protein conformations with distinct pathophysiological functions. The binding of the native, pentameric CRP (pCRP) to activated cell membranes leads to a conformational change resulting in two highly pro-inflammatory isoforms, pCRP* and monomeric CRP (mCRP). The deposition of these pro-inflammatory isoforms has been shown to aggravate the localized tissue injury in a broad range of pathological conditions including atherosclerosis and thrombosis, myocardial infarction, and stroke. Here, we review recent findings on how these structural changes contribute to the inflammatory response and discuss the transitional changes in the structure of CRP as a novel therapeutic target in cardiovascular diseases and overshooting inflammation.

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 apheresis in acute myocardial infarction and COVID-19]

C‑reactive protein (CRP) is the best-known acute phase protein. In humans, inflammation and infection are usually accompanied by an increase in CRP levels in the blood, which is why CRP is an important biomarker in daily clinical routine. CRP can mediate the initiation of phagocytosis by labeling damaged cells. This labeling leads to activation of the classical complement pathway (up to C4) and ends in the elimination of pathogens or reversibly damaged or dead cells. This seems to make sense in case of an external wound of the body. However, in the case of "internal wounds" (e.g., myocardial infarction, stroke), CRP induces tissue damage to potentially regenerable tissue by cell labeling, which has corresponding deleterious effects on cardiac and brain tissue or function. The described labeling of ischemic but potentially regenerable cells by CRP apparently also occurs in coronavirus disease 2019 (COVID-19). Parts of the lung become ischemic due to intra-alveolar edema and hemorrhage, and this is accompanied by a dramatic increase in CRP. Use of selective immunoadsorption of CRP from blood plasma ("CRP apheresis") to rapidly and efficiently lower the fulminant CRP load in the body fills this pharmacotherapeutic gap. With CRP apheresis, it is possible for the first time to remove this pathological molecule quickly and efficiently in clinical practice.

Seven COVID-19 Patients Treated with C-Reactive Protein (CRP) Apheresis

Background: The fulminant course of COVID-19, triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), presents with a high mortality rate and still lacks a causative treatment. C-reactive protein (CRP) has been shown to increase dramatically during the disease progression and correlates with deleterious outcomes. Selective CRP apheresis can reduce circulating CRP levels fast and effective. Methods: Seven hospitalized patients with documented severe COVID-19 progression, elevated CRP plasma levels (>100 mg/L) and signs of respiratory failure were treated with CRP apheresis. Two to twelve CRP apheresis sessions were performed generally in 24 h time intervals and depending on CRP plasma levels. Results: All patients had comorbidities. CRP apheresis reduced CRP plasma levels by up to 84% within a few hours, without exhibiting side effects in any patient. Despite signs of severe lung infiltration in all patients, only one patient died. The other patients showed improvements within the chest X-ray after CRP apheresis and were able to recover regardless of intubation and/or ECMO (4 patients). All remaining six patients were discharged from the hospital in good clinical condition. Conclusions: This case series presents a mortality rate of only 14%, which is dramatically lower than expected from the presented CRP levels as well as comorbidities and ventilation requirements. Our clinical observations regarding the here presented seven patients support the hypothesis that CRP is a candidate to be therapeutically targeted in the early stage of severe COVID-19.

Secretory quality control constrains functional selection-associated protein structure innovation

Biophysical models suggest a dominant role of structural over functional constraints in shaping protein evolution. Selection on structural constraints is linked closely to expression levels of proteins, which together with structure-associated activities determine in vivo functions of proteins. Here we show that despite the up to two orders of magnitude differences in levels of C-reactive protein (CRP) in distinct species, the in vivo functions of CRP are paradoxically conserved. Such a pronounced level-function mismatch cannot be explained by activities associated with the conserved native structure, but is coupled to hidden activities associated with the unfolded, activated conformation. This is not the result of selection on structural constraints like foldability and stability, but is achieved by folding determinants-mediated functional selection that keeps a confined carrier structure to pass the stringent eukaryotic quality control on secretion. Further analysis suggests a folding threshold model which may partly explain the mismatch between the vast sequence space and the limited structure space of proteins.

The mismatch in the conserved structure but different expression levels of C-reactive protein (CRP) in distinct species is reconciled by functional selection on hidden activities of unfolded CRPs.

Extracellular Vesicles Linking Inflammation, Cancer and Thrombotic Risks

Extracellular vesicles (EVs) being defined as lipid-bilayer encircled particles are released by almost all known mammalian cell types and represent a heterogenous set of cell fragments that are found in the blood circulation and all other known body fluids. The current nomenclature distinguishes mainly three forms: microvesicles, which are formed by budding from the plasma membrane; exosomes, which are released, when endosomes with intraluminal vesicles fuse with the plasma membrane; and apoptotic bodies representing fragments of apoptotic cells. Their importance for a great variety of biological processes became increasingly evident in the last decade when it was discovered that they contribute to intercellular communication by transferring nucleotides and proteins to recipient cells. In this review, we delineate several aspects of their isolation, purification, and analysis; and discuss some pitfalls that have to be considered therein. Further on, we describe various cellular sources of EVs and explain with different examples, how they link cancer and inflammatory conditions with thrombotic processes. In particular, we elaborate on the roles of EVs in cancer-associated thrombosis and COVID-19, representing two important paradigms, where local pathological processes have systemic effects in the whole organism at least in part via EVs. Finally, we also discuss possible developments of the field in the future and how EVs might be used as biomarkers for diagnosis, and as vehicles for therapeutics.

Exosomes for Regulation of Immune Responses and Immunotherapy

Exosomes are membrane-enveloped nanosized (30–150 nm) extracellular vesicles of endosomal origin produced by almost all cell types and encompass a multitude of functioning biomolecules. Exosomes have been considered crucial players of cell-to-cell communication in physiological and pathological conditions. Accumulating evidence suggests that exosomes can modulate the immune system by delivering a plethora of signals that can either stimulate or suppress immune responses, which have potential applications as immunotherapies for cancer and autoimmune diseases. Here, we discuss the current knowledge about the active biomolecular components of exosomes that contribute to exosomal function in modulating different immune cells and also how these immune cell-derived exosomes play critical roles in immune responses. We further discuss the translational potential of engineered exosomes as immunotherapeutic agents with their advantages over conventional nanocarriers for drug delivery and ongoing clinical trials.

Single-Molecule Identification of the Conformations of Human C-Reactive Protein and Its Aptamer Complex with Solid-State Nanopores

Human C-reactive protein (CRP) is an established inflammatory biomarker and was proved to be potentially relevant to disease pathology and cancer progression. A large body of methodologies have been reported for CRP analysis, including electrochemical/optical biosensors, aptamer, or antibody-based detection. Although the detection limit is rather low until pg/uL, most of which are time-consuming and relatively expensive, and few of them provided CRP single-molecule information. This work demonstrated the nanopore-based approach for the characterization of CRP conformation under versatile conditions. With an optimized pore of 14 nm in diameter, we achieved the detection limit as low as 0.3 ng/μL, voltage polarity significantly influences the electro-osmotic force and CRP translocation behavior, and the pentameric conformation of CRP may dissociate into pro-inflammatory CRP isoforms and monomeric CRP at bias potential above 300 mV. CRP tends to translocate through nanopores faster along with the increase in pH values, due to more surface charge on both CRP and pore inner wall and stronger electro-osmotic force. The CRP could specifically bind with its aptamer of different concentrations to form complexes, and the complexes exhibited distinguishable nanopore translocation behavior compared with CRP alone. The variation of the molar ratio of aptamer significantly influences the orientation of CRP translocation. The plasma test under physiological conditions displayed the ability of the nanopore system on the CRP identification with a concentration of 3 ng/μL.

Cryo-Electron Microscopy and Biochemical Analysis Offer Insights Into the Effects of Acidic pH, Such as Occur During Acidosis, on the Complement Binding Properties of C-Reactive Protein

The pentraxin family of proteins includes C-reactive protein (CRP), a canonical marker for the acute phase inflammatory response. As compared to normal physiological conditions in human serum, under conditions associated with damage and inflammation, such as acidosis and the oxidative burst, CRP exhibits modulated biochemical properties that may have a structural basis. Here, we explore how pH and ligand binding affect the structure and biochemical properties of CRP. Cryo-electron microscopy was used to solve structures of CRP at pH 7.5 or pH 5 and in the presence or absence of the ligand phosphocholine (PCh), which yielded 7 new high-resolution structures of CRP, including pentameric and decameric complexes. Structures previously derived from crystallography were imperfect pentagons, as shown by the variable angles between each subunit, whereas pentameric CRP derived from cryoEM was found to have C5 symmetry, with subunits forming a regular pentagon with equal angles. This discrepancy indicates flexibility at the interfaces of monomers that may relate to activation of the complement system by the C1 complex. CRP also appears to readily decamerise in solution into dimers of pentamers, which obscures the postulated binding sites for C1. Subtle structural rearrangements were observed between the conditions tested, including a putative change in histidine protonation that may prime the disulphide bridges for reduction and enhanced ability to activate the immune system. Enzyme-linked immunosorbent assays showed that CRP had markedly increased association to the C1 complex and immunoglobulins under conditions associated with acidosis, whilst a reduction in the Ca²⁺ concentration lowered this pH-sensitivity for C1q, but not immunoglobulins, suggesting different modes of binding. These data suggest a model whereby a change in the ionic nature of CRP and immunological proteins can make it more adhesive to potential ligands without large structural rearrangements.

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.

Neuroinflammatory Modulation of Extracellular Vesicle Biogenesis and Cargo Loading

Increasing evidence suggests neuroinflammation is a highly coordinated response involving multiple cell types and utilising several different forms of cellular communication. In addition to the well documented cytokine and chemokine messengers, extracellular vesicles (EVs) have emerged as key regulators of the inflammatory response. EVs act as vectors of intercellular communication, capable of travelling between different cells and tissues to deliver selectively packaged protein, miRNA, and lipids from the parent cell. During neuroinflammation, EVs transmit specific inflammatory mediators, particularly from microglia, to promote inflammatory resolution. This mini-review will highlight the novel neuroinflammatory mechanisms contributing to the biogenesis and selective packaging of EVs.