C-reactive protein as a regulator of autoimmunity and inflammation

Plasmonic Biosensors for Health Monitoring: Inflammation Biomarker Detection

Surface plasmon resonance (SPR) and localized SPR (LSPR) biosensors have emerged as viable technologies in the clinical detection of biomarkers for a wide array of health conditions. The success of SPR biosensors lies in their ability to monitor in real-time label-free biomarkers in complex biofluids. Recent breakthroughs in nanotechnology and surface chemistry have significantly improved this feature, notably from the incorporation of advanced nanomaterials including gold nanoparticles, graphene, and carbon nanotubes providing better SPR sensor performance in terms of detection limits, stability, and specificity. Recent progress in microfluidic integration has enabled SPR biosensors to detect multiple biomarkers simultaneously in complex biological samples. Taken together, these advances are closing the gap for their use in clinical diagnostics and point-of-care (POC) applications. While broadly applicable, the latest advancements in plasmonic biosensing are overviewed using inflammation biomarkers C-reactive protein (CRP), interleukins (ILs), tumor necrosis factor-α (TNF-α), procalcitonin (PCT), ferritin, and fibrinogen for a series of conditions, including cardiovascular diseases, autoimmune disorders, infections, and sepsis, as a key example of plasmonic biosensors for clinical applications. We highlight developments in sensor design, nanomaterial integration, surface functionalization, and multiplexing and provide a look forward to clinical applications by assessing the current limitations and exploring future directions for translating SPR biosensors for diagnostics and health monitoring. By enhancement of diagnostic accuracy, reproducibility, and accessibility, particularly in POC settings, SPR biosensors have the potential to significantly contribute to personalized healthcare and bring real-time, high-precision diagnostics to the forefront of clinical practice.

The relationship between serum vitamin C levels and high-sensitivity C-reactive protein in children

The relationship between vitamin C nutritional status and inflammation has garnered increasing attention, but studies in younger populations are limited. This study aimed to investigate the association between serum vitamin C and high-sensitivity C-reactive protein (hs-CRP) levels in children and adolescents. A cross-sectional analysis was conducted using data from the National Health and Nutrition Examination Survey (NHANES). The demographic data of 1766 participants aged 6-19 years were analyzed using t-tests and chi-square tests. The relationship between serum vitamin C and hs-CRP levels was analyzed using logistic regression, trend tests, and smooth curve fitting. Subgroup analyses and interaction tests were performed to assess the stability of the relationship across different populations. Our findings indicated a negative correlation between serum vitamin C and hs-CRP levels. In the fully adjusted model, each unit increase in serum vitamin C was associated with a reduction of 0.84 mg/L in hs-CRP levels (β = -0.84, 95% confidence interval [CI]: -1.34, -0.35). The hs-CRP levels in the vitamin C saturating group were 3.04 mg/L lower than those in the deficiency group (β = -3.04, 95% CI: -4.99, -1.08). This correlation was more significant in males, individuals with a family income to poverty ratio of ≤ 1.3, and those with a body mass index of ≥ 30 kg/m2. Serum vitamin C levels were negatively correlated with hs-CRP levels in American children and adolescents aged 6-19 years. Males, individuals from low-income families, and those who are overweight derived greater benefits from higher serum vitamin C concentrations.

Severe acute urticaria is associated with elevated plasma levels of D-dimer

Evaluation of the disease severity of acute urticaria (AU) is essential for adequate treatment of patients. However, there are no reliable biomarkers for such an evaluation. In our department, we observed patients with severe AU having elevated plasma D-dimer levels. Thus, the objective of this study was to investigate the elevated D-dimer levels in patients with severe AU in more detail. One hundred and thirty-nine hospital patients diagnosed with severe AU were enrolled. Clinical laboratory data were collected from electronic medical records. One hundred and seventeen of the patients presented with elevated plasma D-dimer levels. Compared to the normal group, the elevated group had a significantly higher proportion of patients who were female, younger, febrile, and had a shorter prehospital time (P < 0.05). Univariate regression analysis showed that neutrophil percentage, C-reactive protein (CRP), and lactate dehydrogenase (LDH) levels increased as D-dimer levels increased, while prehospital time showed the opposite trend. Multiple regression analysis was used to estimate the simultaneous effects of CRP and LDH on D-dimer levels. Patients who responded to additional antibiotic treatment had higher levels of D-dimer. The group with highly elevated D-dimer levels required a higher maximum dose of daily glucocorticoids (GCs) to control the symptoms of AU. In conclusion, patients with severe AU might have elevated plasma D-dimer levels, which are positively correlated with CRP and LDH levels. Patients with severe AU with dramatically elevated D-dimer levels might need a higher dose of daily GCs and antibiotics to relieve symptoms. D-dimer may be a reasonable marker to evaluate the severity of AU and guide treatment.

The cross-sectional relationship between vitamin C and high-sensitivity C-reactive protein levels: insights from NHANES database

Background

Ascorbic acid or vitamin C has antioxidant and anti-inflammatory properties that may impact markers of inflammation like C-reactive protein (CRP). However, studies specifically on vitamin C and high-sensitivity CRP (hs-CRP) have been scarce.

Methods

We conducted a cross-sectional analysis of the National Health and Nutrition Examination Survey 2017-2018 dataset including 5,380 U.S. adults aged ≥20 years. Multiple regression models examined the relationship between plasma vitamin C and serum hs-CRP while adjusting for potential confounders. Stratified analyses and curve fitting assessed effect modification and nonlinearity.

Results

An inverse association was found between plasma vitamin C and serum hs-CRP overall (β = -0.025, 95% CI: -0.033 to -0.017, p < 0.00001) and in subgroups except for the "other Hispanic" subgroup in model II (β = -0.009, 95% CI: (-0.040, 0.023), p = 0.5885). The relationship was nonlinear, with the greatest hs-CRP reduction observed up to a plasma vitamin C level of 53.1 μmol/L.

Conclusion

The results showed a non-linear negative correlation between vitamin C levels and hs-CRP in adults. These results suggest vitamin C intake may reduce inflammation and cardiovascular risk, but only up to 53.1 μmol/L plasma vitamin C.

Advancements in the Management of Severe Community-Acquired Pneumonia: A Comprehensive Narrative Review

Pneumonia, classified as a lower respiratory tract illness, affects different parts of the bronchial system as well as alveoli and can present with varying severities depending on co-morbidities and causative pathogens. It can be broadly classified using the setting in which it was acquired, namely the community or hospital setting, the former being more common and spreading through person-to-person droplet transmission. Community-acquired pneumonia (CAP) is currently the fourth leading cause of death worldwide, and its high mortality makes continual insight into the management of the condition worthwhile. This review explores the literature specifically for severe CAP (sCAP) and delves into the diagnosis, various modalities of treatment, and management of the condition. This condition can be defined as pneumonia requiring mechanical ventilation in the ICU and/or presenting with sepsis and organ failure due to pneumonia. The disease process is characterized by inflammation of the lung parenchyma, initiated by a combination of pathogens and lowered local defenses. Acute diagnosis of the condition is vital in reducing negative patient outcomes, namely through clinical presentation, blood/sputum cultures, imaging modalities such as computed tomography scan, and inflammatory markers, identifying common causative pathogens such as Streptococcus pneumoniae, rhinovirus, Legionella, and viral influenza. Pathogens such as Escherichia coli should also be investigated in patients with chronic obstructive pulmonary disease. The mainstay of treating sCAP includes rapid ICU admission once a diagnosis has been confirmed, initiating sepsis protocol, and treatment with combined empiric antibiotic regimens consisting of beta-lactams and macrolides. Corticosteroid use alongside antibiotics shows promise in reducing inflammation, but its use has to be judged on a case-by-case basis. New drugs such as omadacycline, delafloxacin, and zabofloxacin have shown valid evidence for the treatment of resistant causative organisms. The main guidelines for preventing sCAP include maintaining a healthy lifestyle, and annual pneumococcal and influenza vaccines are recommended for the most vulnerable patient groups, such as those with COPD and immunosuppression.

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.

Engineering and Development of a Tissue Model for the Evaluation of Microneedle Penetration Ability, Drug Diffusion, Photothermal Activity, and Ultrasound Imaging: A Promising Surrogate to Ex Vivo and In Vivo Tissues

Driven by regulatory authorities and the ever-growing demands from industry, various artificial tissue models have been developed. Nevertheless, there is no model to date that is capable of mimicking the biomechanical properties of the skin whilst exhibiting the hydrophilicity/hydrophobicity properties of the skin layers. As a proof-of-concept study, tissue surrogates based on gel and silicone are fabricated for the evaluation of microneedle penetration, drug diffusion, photothermal activity, and ultrasound bioimaging. The silicone layer aims to imitate the stratum corneum while the gel layer aims to mimic the water-rich viable epidermis and dermis present in in vivo tissues. The diffusion of drugs across the tissue model is assessed, and the results reveal that the proposed tissue model shows similar behavior to a cancerous kidney. In place of typical in vitro aqueous solutions, this model can also be employed for evaluating the photoactivity of photothermal agents since the tissue model shows a similar heating profile to skin of mice when irradiated with near-infrared laser. In addition, the designed tissue model exhibits promising results for biomedical applications in optical coherence tomography and ultrasound imaging. Such a tissue model paves the way to reduce the use of animals testing in research whilst obviating ethical concerns.

Marburg and Ebola Virus Infections Elicit a Complex, Muted Inflammatory State in Bats

The Marburg and Ebola filoviruses cause a severe, often fatal, disease in humans and nonhuman primates but have only subclinical effects in bats, including Egyptian rousettes, which are a natural reservoir of Marburg virus. A fundamental question is why these viruses are highly pathogenic in humans but fail to cause disease in bats. To address this question, we infected one cohort of Egyptian rousette bats with Marburg virus and another cohort with Ebola virus and harvested multiple tissues for mRNA expression analysis. While virus transcripts were found primarily in the liver, principal component analysis (PCA) revealed coordinated changes across multiple tissues. Gene signatures in kidney and liver pointed at induction of vasodilation, reduction in coagulation, and changes in the regulation of iron metabolism. Signatures of immune response detected in spleen and liver indicated a robust anti-inflammatory state signified by macrophages in the M2 state and an active T cell response. The evolutionary divergence between bats and humans of many responsive genes might provide a framework for understanding the differing outcomes upon infection by filoviruses. In this study, we outline multiple interconnected pathways that respond to infection by MARV and EBOV, providing insights into the complexity of the mechanisms that enable bats to resist the disease caused by filoviral infections. The results have the potential to aid in the development of new strategies to effectively mitigate and treat the disease caused by these viruses in humans.

The importance of biological sex in cardiac cachexia

Cardiac cachexia is a catabolic muscle wasting syndrome observed in approximately 1 in 10 heart failure patients. Increased skeletal muscle atrophy leads to frailty and limits mobility which impacts quality of life, exacerbates clinical care, and is associated with higher rates of mortality. Heart failure is known to exhibit a wide range of prevalence and severity when examined across individuals of different ages and with co-morbidities related to diabetes, renal failure and pulmonary dysfunction. It is also recognized that men and women exhibit striking differences in the pathophysiology of heart failure as well as skeletal muscle homeostasis. Given that both skeletal muscle and heart failure physiology are in-part sex dependent, the diagnosis and treatment of cachexia in heart failure patients may depend on a comprehensive examination of how these organs interact. In this review we explore the potential for sex-specific differences in cardiac cachexia. We summarize advantages and disadvantages of clinical methods used to measure muscle mass and function and provide alternative measurements that should be considered in preclinical studies. Additionally, we summarize sex-dependent effects on muscle wasting in preclinical models of heart failure, disuse, and cancer. Lastly, we discuss the endocrine function of the heart and outline unanswered questions that could directly impact patient care.

Targeting C-Reactive Protein by Selective Apheresis in Humans: Pros and Cons

C-reactive protein (CRP), the prototype human acute phase protein, may be causally involved in various human diseases. As CRP has appeared much earlier in evolution than antibodies and nonetheless partly utilizes the same biological structures, it is likely that CRP has been the first antibody-like molecule in the evolution of the immune system. Like antibodies, CRP may cause autoimmune reactions in a variety of human pathologies. Consequently, therapeutic targeting of CRP may be of utmost interest in human medicine. Over the past two decades, however, pharmacological targeting of CRP has turned out to be extremely difficult. Currently, the easiest, most effective and clinically safest method to target CRP in humans may be the specific extracorporeal removal of CRP by selective apheresis. The latter has recently shown promising therapeutic effects, especially in acute myocardial infarction and COVID-19 pneumonia. This review summarizes the pros and cons of applying this novel technology to patients suffering from various diseases, with a focus on its use in cardiovascular medicine.

Soluble pattern recognition molecules: Guardians and regulators of homeostasis at airway mucosal surfaces

Maintenance of homeostasis at body barriers that are constantly challenged by microbes, toxins and potentially bioactive (macro)molecules requires complex, highly orchestrated mechanisms of protection. Recent discoveries in respiratory research have shed light on the unprecedented role of airway epithelial cells (AEC), which, besides immune cells homing to the lung, also significantly contribute to host defence by expressing membrane‐bound and soluble pattern recognition receptors (sPRR). Recent evidence suggests that distinct, evolutionary ancient, sPRR secreted by AEC might become activated by usually innocuous proteins, commonly referred to as allergens. We here provide a systematic overview on sPRR detectable in the mucus lining of AEC. Some of them become actively produced and secreted by AECs (like the pentraxins C‐reactive protein and pentraxin 3; the collectins mannose binding protein and surfactant proteins A and D; H‐ficolin; serum amyloid A; and the complement components C3 and C5). Others are elaborated by innate and adaptive immune cells such as monocytes/macrophages and T cells (like the pentraxins C‐reactive protein and pentraxin 3; L‐ficolin; serum amyloid A; and the complement components C3 and C5). Herein we discuss how sPRRs may contribute to homeostasis but sometimes also to overt disease (e.g. airway hyperreactivity and asthma) at the alveolar–air interface.

Diagnostic markers for community-acquired pneumonia

Community-acquired pneumonia (CAP) is one of the respiratory infectious diseases caused by not only bacteria, but also viruses. Antibiotic agents are needed to treat only bacterial but not viral CAP. In addition, there are some non-infectious respiratory diseases in the differential diagnosis of CAP, such as malignant diseases, interstitial lung diseases, pulmonary edema, and pulmonary hemorrhage. We usually diagnose patients having CAP by comprehensive evaluation of symptoms, vital signs, laboratory examinations, and radiographic examinations. However, symptoms and vital signs are not specific for the diagnosis of CAP; therefore, we also use inflammatory biomarkers for differentiating bacterial from viral CAP and non-infectious respiratory diseases. We have used the white blood cell count, C-reactive protein (CRP), and erythrocyte sedimentation rate as common inflammatory biomarkers, but they are not specific for bacterial infection because they could be increased by malignant diseases and collagen diseases. Recently, some inflammatory biomarkers such as procalcitonin (PCT), soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), pro-adrenomedullin (proADM), and presepsin have been developed as relatively specific biomarkers for bacterial infection. Many reports have evaluated the usefulness of PCT for diagnosing CAP. In this review, the characteristics of each biomarker are discussed based on previous studies.

The Multiple Faces of C-Reactive Protein-Physiological and Pathophysiological Implications in Cardiovascular Disease

C-reactive protein (CRP) is an intriguing protein which plays a variety of roles in either physiological or pathophysiological states. For years it has been regarded merely as a useful biomarker of infection, tissue injury and inflammation, and it was only in the early 80s that the modified isoforms (mCRP) of native CRP (nCRP) appeared. It soon became clear that the roles of native CRP should be clearly discriminated from those of the modified form and so the impacts of both isoforms were divided to a certain degree between physiological and pathophysiological states. For decades, CRP has been regarded only as a hallmark of inflammation; however, it has since been recognised as a significant predictor of future episodes of cardiovascular disease, independent of other risk factors. The existence of modified CRP isoforms and their possible relevance to various pathophysiological conditions, suggested over thirty years ago, has prompted the search for structural and functional dissimilarities between the pentameric nCRP and monomeric mCRP isoforms. New attempts to identify the possible relevance between the diversity of structures and their opposing functions have initiated a new era of research on C-reactive protein. This review discusses the biochemical aspects of CRP physiology, emphasizing the supposed relevance between the structural biology of CRP isoforms and their differentiated physiological and pathophysiological roles.

Aging-associated latent herpes viral infection in normal Japanese individuals and patients with Werner syndrome

A series of our "inflammageing" study examining serum samples from a maximum of 217 healthy Japanese individuals aged between 1 and 100 years and mutation-proven 40 patients with Werner syndrome (WS) indicated normal aging-associated elevations of highly sensitive CRP (hsCRP) and matrix metalloproteinase-9 (MMP-9). To further study the contribution of environmental factors such as persistent herpes viral infection to inflammageing, IgG antibodies against varicella/zoster virus (VZV) and cytomegalovirus (CMV) were examined in the same serum samples as has been done for hsCRP and MMP-9 analyses. The mean levels of serum IgG viral antibodies were comparable between normal (mean ± SE: 31.0 ± 4.3 unit) and WS (38.6 ± 7.6) for CMV, and between normal (42.0 ± 12.2) and WS (29.8 ± 3.8) for VZV, respectively. Significant associations of aging with IgG anti-CMV antibody were in normal aging (p = 0.023) and WS (p = 0.037), but not with IgG VZV in both conditions. Aging-associated change of IgG anti-CMV antibody titer in WS increased significantly (1.32 times higher) compared with normal aging (p = 0.037). IgG anti-CMV level was significantly elevated in the male gender than female in both conditions (p = 0.006). Elevated hsCRP level was significantly associated with IgG anti-CMV (p = 0.016) and IgG anti-VZV (p = 0.008) antibodies in normal aging, but not in WS. Serum MMP-9 was significantly associated with IgG anti-CMV level (p = 0.0002) in normal aging, but not in WS. Persistent herpes viral infection may constitute a part of "inflammageing" in normal aging and WS.

Acute-phase response and its biomarkers in acute and chronic urticaria

Introduction

Since urticaria is a persisting inflammatory disease it is important to establish the prognostic factors for the duration and severity of the disease.

Aim

To evaluate serum concentrations of selected acute-phase proteins (APP) in patients with various forms of urticaria as compared to healthy volunteers and also to analyze these concentrations in different types of urticaria. Additionally, to evaluate the correlation between serum levels of selected APP and disease activity.

Material and methods

Serum concentrations of C-reactive protein (CRP), α₁-acid glycoprotein (AGP), α₁-antichymotrypsin (ACT), α₁-antitrypsin (AT), ceruloplasmin (Cp), transferrin (Tf), α₂-macroglobulin (α₂M) and haptoglobin (Hp) were measured. Quantitative measurement was conducted using the rocket immunoelectrophoresis. Disease activity was assessed with the use of total symptom score.

Results

Analysis of serum APP concentrations revealed statistically higher serum concentrations of CRP, AGP and ACT in the entire group of patients with urticaria in comparison with the control group. In the entire group of patients with urticaria, CRP, AGP, ACT, Cp and Hp correlated positively with disease activity, intensity of pruritus and the number and size of urticarial wheals. Statistically lower serum concentrations of CRP, ACT, Cp and Hp were detected in the group of patients with acute urticaria (AU) and angioedema together, compared to the patients suffering from AU only.

Conclusions

Patients with symptoms of various forms of urticaria present a distinct profile of serum APP concentrations. A significant correlation observed between CRP, AGP, ACT, Cp, Hp and clinical activity score points to the potential role of APP as markers of the urticarial activity.

Effect of serum inflammatory markers on the prognosis of adult and pediatric patients with Guillain-Barré syndrome

OBJECTIVE

The aim of this study was to evaluate blood neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), C-reactive protein (CRP), and albumin levels for their prognostic value in adult Guillain-Barré syndrome (GBS-A) and pediatric Guillain-Barré syndrome (GBS-P) patients.

PATIENTS AND METHODS

We retrospectively analyzed the medical records of 68 Guillain-Barré syndrome (GBS) patients (36 adults, 32 children) who were treated as inpatients at Harran University Faculty of Medicine, Neurology and Pediatric Neurology Departments. The pretreatment NLR, PLR, CRP, and albumin levels and Hughes scores at hospital admission, discharge, and third-month control were documented.

RESULTS

In GBS-A patients, the mean CRP and NLR levels at admission/discharge and third-month control were significantly higher, and the mean albumin level was significantly lower in the Hughes disability scale (HDS)≥3 group. In GBS-P group, the mean NLR level at third month was significantly higher in the HDS≥3 group. GBS-A patients had higher mean NLR, PLR, and CRP levels and lower mean albumin values than GBS-P patients. Both GBS-A and GBS-P patients had higher mean NLR, PLR, and CRP levels and lower mean albumin values than healthy controls. Only the albumin level of the GBS-A group was found to be a significant predictor of prognosis at discharge from hospital.

CONCLUSION

NLR, CRP, and albumin levels in the GBS-A group and NLR levels in the GBS-P group may be helpful in predicting the prognosis of the disease. The albumin level of GBS-A patients is an independent risk factor for prognosis at discharge from hospital.

Inflammageing assessed by MMP9 in normal Japanese individuals and the patients with Werner syndrome

Age-associated minor inflammation: inflammageing may explain human ageing mechanism(s). Our previous study reported a significant increase in the serum level of highly sensitive C-reactive protein (hsCRP) with normal ageing and the patients with Werner syndrome (WS). To further study the minor inflammatory condition associated with ageing, another possible ageing biomarker: matrix metalloproteinase-9 (MMP9) was examined in the sera from 217 normal Japanese individuals aged between 1 and 100 years and 41 mutation-proven Japanese WS aged between 32 and 70 years. MMP9 was assayed by ELISA. The serum level of MMP9 was elevated significantly (p < 0.001) with normal ageing from both sexes as hsCRP. In contrast to normal ageing, the serum MMP9 level in WS decreased significantly with calendar age (p < 0.05). The MMP9 level (ng/mL) in WS (147.2 ± 28.5) was not significantly different in comparison with those from age-matched normal adult population aged between 25 and 70 years (109.1 ± 9.4), nor normal elderly population aged between 71 and 100 years (179.9 ± 16.1). Although both normal ageing and WS were associated with minor inflammation, the inflammatory parameters such as serum MMP9 and hsCRP changed differently between normal ageing and WS. The WS-specific chronic inflammation including skin ulcer and diabetes mellitus may contribute the different behavior of both ageing biomarkers from normal ageing.

Increased Kappa/Lambda Hybrid Antibody in Serum Is a Novel Biomarker Related to Disease Activity and Inflammation in Rheumatoid Arthritis

The κ/λ hybrid antibodies in normal human serum were reported recently, but their clinical relevance has not yet been explored. Rheumatoid arthritis (RA) is one of the major joint diseases, and the early diagnosis and treatment of RA remain a challenge. Here, we developed a double-sandwich enzyme-linked immunosorbent assay system to quantify relative serum κ/λ hybrid antibody levels in RA patients, osteoarthritis (OA) patients, and healthy controls (HC) in order to assess their potential use as a serological biomarker of early disease and clinical activity and to preliminarily investigate their immunomodulatory roles in RA. Surprisingly, we found that κ/λ hybrid antibody was markedly increased in both early and established RA. Serum κ/λ hybrid antibody levels were significantly correlated with clinical indexes and inflammatory markers in RA. Further analysis showed a positive correlation between κ/λ hybrid antibody levels and the 28-joint disease activity score (DAS28). In conclusion, serum κ/λ hybrid antibodies in RA were identified for the first time. High levels of κ/λ hybrid antibody may be a useful tool in distinguishing early RA from OA and HC. We suggest κ/λ hybrid antibody as a marker for disease activity. The increased κ/λ hybrid antibodies were associated with inflammatory conditions in RA.

Monomeric C-reactive protein inhibits renal cell-directed complement activation mediated by properdin

Previous studies have shown that complement activation on renal tubular cells is involved in the induction of interstitial fibrosis and cellular injury. Evidence suggests that the tubular cell damage is initiated by the alternative pathway (AP) of complement with properdin having an instrumental role. Properdin is a positive regulator of the AP, which can bind necrotic cells as well as viable proximal tubular epithelial cells (PTECs), inducing complement activation. Various studies have indicated that in the circulation there is an unidentified inhibitor of properdin. We investigated the ability of C-reactive protein (CRP), both in its monomeric (mCRP) and pentameric (pCRP) form, to inhibit AP activation and injury in vitro on renal tubular cells by fluorescent microscopy, ELISA, and flow cytometry. We demonstrated that preincubation of properdin with normal human serum inhibits properdin binding to viable PTECs. We identified mCRP as a factor able to bind to properdin in solution, thereby inhibiting its binding to PTECs. In contrast, pCRP exhibited no such binding and inhibitory effect. Furthermore, mCRP was able to inhibit properdin-directed C3 and C5b-9 deposition on viable PTECs. The inhibitory ability of mCRP was not unique for viable cells but also demonstrated for binding to necrotic Jurkat cells, a target for properdin binding and complement activation. In summary, mCRP is an inhibitor of properdin in both binding to necrotic cells and viable renal cells, regulating complement activation on the cell surface. We propose that mCRP limits amplification of tissue injury by controlling properdin-directed complement activation by damaged tissue and cells.

Multiplex cytokine analysis of Werner syndrome

We reported a minor inflammation-driven ageing (inflammageing) assessed by highly sensitive CRP (hsCRP) in normal individuals and patients with Werner syndrome (WS), followed by an ageing associated Th2-biased cytokine change in normal ageing in the previous papers. To further study the association of hsCRP and 26 cytokines/chemokines in 35 WS patients, a multiple cytokine array system was used in the same serum samples as were examined for hsCRP. The serum levels of Th2 cytokines (IL-4, IL-6, IL-10, and GM-CSF), Th1 products (IL-2, TNFα, IL-12, and IFNγ) and monocyte/macrophage products (MCP-1, basic FGF and G-CSF) in WS were significantly elevated compared with normal ageing. Elevated hsCRP level in WS was significantly correlated with IL-6, IL-12 and VEGF levels, if age and sex were taken into account. A pro-inflammatory cytokine/chemokine circuit-stimulated immunological shift to Th2 in WS was similar to normal ageing. These cytokine/chemokine changes may induce a systemic chronic inflammation monitored by hsCRP, though these immunological changes in WS were more complicated than normal ageing, possibly due to the WS-specific chronic inflammation such as skin ulcer, diabetes mellitus and central obesity with visceral fat deposition. Further study may warrant the pathophysiology of Th2 shift and Th2-biased inflammageing in normal ageing and WS.

Elevated Membrane and Soluble CD64: A Novel Marker Reflecting Altered FcγR Function and Disease in Early Rheumatoid Arthritis That Can Be Regulated by Anti-Rheumatic Treatment

OBJECTIVES

Fc receptors (FcR) interacting with immune complexes (ICs) is a central event in the immune pathogenesis of rheumatoid arthritis (RA). Here we asked if a specific FcR is linked to RA pathogenesis and if FcR activities relate to disease and treatment outcome in early RA.

MATERIAL AND METHODS

Twenty autoantibody-positive RA patients and 33 HC were included. The patients were evaluated before and after treatment with methotrexate and prednisolone. At follow-up, the EULAR response criteria were applied to determine the individual treatment outcomes. Serum immunoglobulin levels were measured and the expression of FcR for IgG (FcγR) and IgA (FcαR) on peripheral blood monocytes were determined by flow cytometry. The monocytic FcγR function was evaluated by human IgG1 and IgG3 IC-binding and TNFα stimulated release. Plasma levels of soluble FcRs (sFcRs) were determined with ELISA.

RESULTS

The IgG1 and IgG3 levels were elevated in the RA sera. The RA monocytes expressed more CD64 and cell surface-bound IgG than HC monocytes, and showed an impaired FcγR function as reflected by changes in IC-binding and decreased IC-stimulated TNFα secretion. These findings correlated significantly with different disease activity markers. Furthermore, sFcRs were elevated in the patient plasma, and sCD64 was specific for RA (compared with a reference group of patients with active psoriatic arthritis). Following treatment, immunoglobulins and sFcR levels were reduced, whereas membrane CD64 was only decreased in patients with good response to treatment.

CONCLUSIONS

Early RA patients display increased membrane and soluble CD64 and an impaired FcγR function correlating with joint disease activity. Beneficial responses of anti-rheumatic treatment in patients reduce CD64. These data suggest sCD64 as an important objective biomarker in RA.

Crystal structures for short-chain pentraxin from zebrafish demonstrate a cyclic trimer with new recognition and effector faces

Short-chain pentraxins (PTXs), including CRP and SAP, are innate pattern recognition receptors that play vital roles in the recognition and elimination of various pathogenic bacteria by triggering the classical complement pathway through C1q. Similar to antibodies, pentraxins can also activate opsonisation and phagocytosis by interacting with Fc receptors (FcRs). Various structural studies on human PTXs have been performed, but there are no reports about the crystal structure of bony fish pentraxins. Here, the crystal structures of zebrafish PTX (Dare-PTX-Ca and Dare-PTX) are presented. Both Dare-PTX-Ca and Dare-PTX are cyclic trimers, which are new forms of crystallised pentraxins. The structures reveal that the ligand-binding pocket (LBP) in the recognition face of Dare-PTX is deep and narrow. Homology modelling shows that LBPs from different Dare-PTX loci differ in shape, reflecting their specific recognition abilities. Furthermore, in comparison with the structure of hCPR, a new C1q binding mode was identified in Dare-PTX. In addition, the FcR-binding sites of hSAP are partially conserved in Dare-PTX. These results will shed light on the understanding of a primitive PTX in bony fish, which evolved approximately 450 million years ago.

A new type of natural bispecific antibody with potential protective effect in Hashimoto thyroiditis

CONTEXT

As a new antibody concept, natural bispecific antibodies (nBsAbs) have been detected in long-term passive immunization and some diseases, but their potential immunomodulatory role remains unclear. Hashimoto thyroiditis (HT) appears to fulfill the condition for nBsAb production but has not yet been characterized.

OBJECTIVE

The objective of the study was to identify a new nBsAb against thyroid peroxidase (TPO) and thyroglobulin (Tg) in HT patients and to preliminarily explore its immunomodulatory role.

DESIGN, SETTING, AND PATIENTS

Serum samples were obtained from 136 HT patients, 92 diseased controls, and 99 healthy controls for anti-TPO/Tg nBsAb detection. The relationship between anti-TPO/Tg nBsAb and other clinical parameters was also analyzed.

MAIN OUTCOME MEASURES

The anti-TPO/Tg nBsAb was detected using a double-antigen sandwich ELISA. Higher nBsAb levels were found to be associated with decreased inflammation in HT patients.

RESULTS

The prevalence of anti-TPO/Tg nBsAb in HT was 44.9% (61 of 136), significantly higher than that of diseased controls (2.2%, 2 of 92) (P < .0001) and healthy controls (0%, 0 of 99) (P < .0001). HT patients who were nBsAb positive were prone to have significantly lower levels of serum C-reactive protein and TNF-α compared with the nBsAb-negative individuals (P < .05). The serum amyloid A and interferon-γ levels also showed a similar trend in the two groups. The IgG subclass of anti-TPO/Tg nBsAb was IgG4. Further analysis showed a negative correlation between anti-TPO/Tg nBsAb and serum total IgG4 (r = -0.697, P = .025) in IgG4 thyroiditis patients.

CONCLUSIONS

A new type of nBsAb against TPO and Tg in HT patients is identified. Our data also indicate a protective effect of anti-TPO/Tg nBsAb in the pathogenesis of HT and extend prior knowledge about nBsAb in diseases.

Aging-associated inflammation in healthy Japanese individuals and patients with Werner syndrome

Minor inflammation-driven aging (inflammaging) has been proposed to explain human aging mechanism. To study the inflammatory condition associated with normal human aging, highly sensitive CRP (hsCRP) was examined in the sera collected from 217 healthy Japanese individuals aged between 1 and 100years and 41 mutation-proven Japanese Werner syndrome (WS) patients. The serum hsCRP was assayed by ELISA. The serum hsCRP level increased significantly (p<0.001) with normal aging from both sexes. The serum hsCRP was significantly elevated in WS (mean±SE: 11.0±1.6μg/ml) compared with age-matched normal population (1.3±0.3μg/ml, p<0.001) and normal elderly population ages between 71 and 100years (4.2±0.7μg/ml, p<0.001). Both normal aging and WS were associated with minor inflammation that can be evaluated by serum hsCRP. WS may be a good candidate to study inflammaging.

Innate immunity and rheumatoid arthritis

Innate immunity, with macrophages playing a central role, is critically important in the pathogenesis of RA. Although environmental insults such as smoking have been implicated in the initiation of rheumatoid arthritis (RA) in patients who express the shared epitope, the understanding of the role of innate immunity in the pathogenesis of this disease is also expanding. As the understanding continues to expand, enticing targets for new therapeutic interventions continue to be identified. This article focuses on cells of myelomonocytic origin, their receptors, and factors that interact with them.

Use of highly sensitive C-reactive protein for followup of Wegener's granulomatosis

OBJECTIVE

Since Wegener's granulomatosis (WG) represents a relapsing disease, efforts have been made to reliably predict relapses using blood tests. Followup measures such as conventionally determined C-reactive protein (CRP), antineutrophil cytoplasmic antibody (C-ANCA) titer, and proteinase-3 (PR3) ELISA are applied. We evaluated whether during remission elevated highly sensitive CRP (hsCRP) precedes relapse as a marker of subclinical inflammation and thus might improve clinical assessment.

METHODS

We investigated 227 sera of 57 patients with WG: 74 sera collected from patients in remission who subsequently relapsed (before relapse), 30 sera collected during relapse, and 123 sera from patients in remission without relapse. We also distinguished between major and minor relapse. hsCRP, conventionally determined CRP (CRP), C-ANCA, PR3-ELISA, and erythrocyte sedimentation rate (ESR) were measured using commercial kits, and levels were correlated to clinical status.

RESULTS

Only hsCRP and ANCA titer, but not CRP levels, were higher in sera from patients who subsequently relapsed versus those who did not, indicating patients at risk. Levels of hsCRP, CRP, and ESR were higher in sera collected during relapse than in the sera before relapse. hsCRP, conventional CRP, and ESR were also higher in samples collected during major relapse than before major relapse. Looking at the levels just before relapse compared to previous levels during remission, none of these measures rose directly before the clinical manifestation of the relapse.

CONCLUSION

Our study provides evidence for an additional value of hsCRP in the clinical assessment of patients with WG.

Biomarkers: a definite plus in pneumonia

During the past few years, biomarkers have emerged as an indispensible tool in the diagnosis of pneumonia. To find an ideal diagnostic biomarker for pneumonia is not an easy task. Not only should it allow an early diagnosis of the condition, but it should also allow differential diagnosis from other noninfectious conditions. Ongoing research is being done in this field so as to put an array of biomarkers at the disposal of doctors to improve the diagnosis of pneumonia when patients present to them with cough or nonspecific symptoms which could easily be misinterpreted as symptoms of other conditions. Procalcitonin and soluble triggering receptor expressed on myeloid cells-1 have emerged as reliable diagnostic markers in pneumonia, and are better when compared to other markers, namely, C-reactive protein, leukocyte count, and proinflammatory cytokines. Many other biomarkers are being studied for their probable use in diagnosing pneumonia but have yet to prove their benefit.

The pattern recognition receptor PTX3 is recruited at the synapse between dying and dendritic cells, and edits the cross-presentation of self, viral, and tumor antigens

Pentraxins are soluble pattern recognition receptors with a dual role: protection against extracellular microbes and autoimmunity. The mechanisms by which they accomplish these tasks are not yet fully understood. Here we show that the prototypic long pentraxin PTX3 is specifically recruited at both sides of the phagocytic synapse between dendritic cells (DCs) and dying cells and remains stably bound to the apoptotic membranes (estimated half-time > 36 hours). Apoptotic cells per se influence the production of PTX3 by maturing DCs. When both microbial stimuli and dying cells are present, PTX3 behaves as a flexible adaptor of DC function, regulating the maturation program and the secretion of soluble factors. Moreover a key event associated with autoimmunity (ie, the cross-presentation of epitopes expressed by apoptotic cells to T cells) abates in the presence of PTX3, as evaluated using self, viral, and tumor-associated model antigens (vinculin, NS3, and MelanA/MART1). In contrast, PTX3 did not influence the presentation of exogenous soluble antigens, an event required for immunity against extracellular pathogens. These data suggest that PTX3 acts as a third-party agent between microbial stimuli and dying cells, contributing to limit tissue damage under inflammatory conditions and the activation of autoreactive T cells.

Increased C-reactive protein in ACE-inhibitor-induced angioedema

AIMS

This study was designed to identify new factors which may contribute to angiotensin-converting-enzyme-inhibitor (ACEI)-induced angioedema.

METHODS

In a retrospective cohort study we examined 25 patients who used an ACEI and presented at our emergency room with acute angioedema as well as 18 patients with unknown cause of angioedema and a total of 21 patients on ACEI-therapy without previous angioedema. We measured markers of inflammation such as acute-phase proteins (C-reactive protein, fibrinogen), leukocyte count and body temperature.

RESULTS

The mean interval between initiation of ACEI treatment and first manifestation of angioedema was 35.8 +/- 5.3 months. During symptomatic angioedema, mean plasma levels of C-reactive protein and fibrinogen were significantly increased by 7.3-fold and 1.5-fold, respectively, while leukocyte count and body temperature were normal. These changes disappeared after successful treatment of angioedema and were not found in patients with angioedema of unknown cause and those receiving ACEI without having experienced angioedema.

CONCLUSION

Our findings demonstrate for the first time that ACEI-induced angioedema is associated with strongly increased plasma levels of CRP. We suggest that CRP is involved in the pathophysiology of ACEI-induced angioedema.

Autoantibodies and self-reported health complaints in relatives of systemic lupus erythematosus patients: a community based approach

First-degree relatives (FDRs) and spouses to a population-derived cohort of lupus patients were investigated for the occurrence of selected autoantibodies and self-reported health complaints. A healthy reference population was included. The lupus population consisted of 103 index cases. A total of 275/375 available relatives accepted to enter the study. Two hundred and twenty-six/315 (72%) were FDRs and 49/60 (82%) were spouses. Serum was analysed for ANA using indirect immunofluorescence on Hep-2 cells at the following dilutions: 1:40, 1:80 and 1:160 and in addition sera were tested for anti-dsDNA, IgM RF, ACA (IgM, IgG), anti-beta2GPI (IgM, IgG) and antibodies to prothrombin. ANA positivity occurred more frequently in FDRs compared with spouses and controls at serum dilution 1:160 (10 versus 0% and 2.5%, respectively, P = 0.04 and P < 0.01), 1:80 (24 versus 4% and 5%, respectively, P = 0.003 and P < 0.001) and 1:40 (31 versus 10% and 10%, respectively, P = 0.006 and P < 0.0001). ANA positivity in FDRs occurred randomly, irrespective of family relationship. Fifty-three/184 versus 2/32 FDRs to patients with definite SLE (D-SLE) and incomplete SLE (I-SLE), respectively, tested ANA positive at 1:80 (P < 0.05). FDRs with ANA titer at 80 were affiliated to lupus probands with high SLICC scores (P < 0.05). Self-reported health complaints, cardiovascular/thromboembolic events in particular, were more frequent among FDRs than in spouses. The population-based approach adopted in the present study supports previous clinic-based evidence of an increased propensity for autoantibody occurrence in relatives to SLE patients. In FDRs, present ANA positivity was associated with increased prevalence of health complaints and ANA positivity in FDRs was related to the criterial burden and cumulated damage in corresponding lupus probands. The low ANA frequency among spouses of SLE patients argues against a significant autoantibody triggering effect of shared environment in adult life.

Reversal of ongoing proteinuria in autoimmune mice by treatment with C-reactive protein

OBJECTIVE

To examine the ability of injection of C-reactive protein (CRP) to treat systemic lupus erythematosus (SLE) in the (NZB x NZW)F(1) (NZB/NZW) mouse and to use a nephrotoxic nephritis (NTN) model to further examine the mechanism of this activity.

METHODS

NZB/NZW mice were given a single injection of 200 mug of CRP prior to disease onset or after the onset of high-grade proteinuria. Mice were monitored weekly for proteinuria and monthly for anti-double-stranded DNA (anti-dsDNA) antibodies. NTN was induced by immunization with rabbit IgG followed by rabbit anti-mouse glomerular basement membrane. Proteinuria was measured daily, and renal pathology was scored. CRP was injected at the time of disease induction or 9 days later.

RESULTS

Treatment of NZB/NZW mice with CRP prior to disease onset delayed the onset of high-grade proteinuria by 16 weeks (P < 0.0001) and prolonged survival by 13 weeks (P < 0.002). CRP treatment of NZB/NZW mice during acute disease rapidly decreased proteinuria, and the treated mice remained aproteinuric for at least 10 weeks. Control and CRP-treated mice developed similar levels of anti-dsDNA. In C57BL/6 mice, injection of CRP either before or after induction of NTN suppressed proteinuria and glomerular pathology. CRP was completely ineffective in treating NTN in interleukin-10 (IL-10)-deficient mice.

CONCLUSION

CRP injection suppresses inflammation in the kidney in SLE and NTN. The requirement for IL-10 in this protection suggests that CRP must rapidly initiate an IL-10-dependent antiinflammatory process. These findings suggest that a major function of CRP during the acute-phase response is to limit tissue damage and modulate acute inflammation.

Prevention and reversal of nephritis in MRL/lpr mice with a single injection of C-reactive protein

OBJECTIVE

C-reactive protein (CRP) is an acute-phase serum protein with binding reactivity to nuclear autoantigens and immunomodulatory function. The MRL/lpr mouse is an important model of human systemic lupus erythematosus (SLE). These mice develop high-titer anti-DNA antibodies and immune complex-mediated nephritis and exhibit progressive lymphadenopathy. The mortality rate among these mice is 50% by age 18-20 weeks; the most frequent cause of death is glomerulonephritis. The present study was undertaken to determine whether treatment of mice with CRP would affect the course of lupus nephritis.

METHODS

MRL/lpr mice were treated with a single 200-mug injection of CRP at either age 6 weeks (before disease onset) or age 13 or 15 weeks (when proteinuria had reached high levels). Proteinuria was measured weekly, and levels of anti-double-stranded DNA autoantibodies and blood urea nitrogen were determined monthly. Glomerular immune complex deposition and renal pathology were assessed in mice ages 15 weeks and 17 weeks.

RESULTS

Early CRP treatment markedly delayed the onset of proteinuria and lymphadenopathy, increased survival, and reduced levels of autoantibodies to DNA. Treatment of mice with active disease reversed proteinuria and prolonged survival. Renal disease was decreased in CRP-treated mice, with a marked suppression of glomerular pathology, tubular degeneration, and interstitial inflammation, which correlated with the decrease in proteinuria and azotemia.

CONCLUSION

These findings demonstrate that systemic suppression of autoimmunity is initiated by a single injection of CRP. Long-term maintenance of CRP-mediated protection was reversed by injection of an anti-CD25 monoclonal antibody but not by macrophage depletion, suggesting that disease suppression is maintained by CD25-bearing T cells.

Serum levels of autoantibodies against monomeric C-reactive protein are correlated with disease activity in systemic lupus erythematosus

This study was performed to investigate the relation between IgG autoantibodies against human C-reactive protein (anti-CRP) and disease activity measures in serial serum samples from 10 patients with systemic lupus erythematosus (SLE), of whom four had active kidney involvement during the study period. The presence of anti-CRP was analysed by enzyme-linked immunosorbent assay. The cut-off for positive anti-CRP test was set at the 95th centile of 100 healthy blood donor sera. Specificity of the anti-CRP antibody binding was evaluated by preincubating patient sera with either native or monomeric CRP. Disease activity was determined by the SLE disease activity index (SLEDAI), serum levels of CRP, anti-DNA antibodies, complement components and blood cell counts. Of 50 serum samples, 20 (40%) contained antibodies reactive with monomeric CRP, and 7 of 10 patients were positive on at least one occasion during the study. All patients with active lupus nephritis were positive for anti-CRP at flare. Frequent correlations between anti-CRP levels and disease activity measures were observed in anti-CRP-positive individuals. Accumulated anti-CRP data from all patients were positively correlated with SLEDAI scores and anti-DNA antibody levels, whereas significant inverse relationships were noted for complement factors C1q, C3 and C4, and for lymphocyte counts. This study confirms the high prevalence of anti-CRP autoantibodies in SLE and that the antibody levels are correlated with clinical and laboratory disease activity measures. This indicates that anti-CRP antibodies might have biological functions of pathogenetic interest in SLE. Further prospective clinical studies and experimental studies on effects mediated by anti-CRP antibodies are warranted.