Autoimmunity to protective molecules: is it the perpetuum mobile (vicious cycle) of autoimmune rheumatic diseases?

Excitable dynamics of flares and relapses in autoimmune diseases

Many autoimmune disorders exhibit flares in which symptoms erupt and then decline, as exemplified by multiple sclerosis (MS) in its relapsing-remitting form. Existing mathematical models of autoimmune flares often assume regular oscillations, failing to capture the stochastic and non-periodic nature of flare-ups. We suggest that autoimmune flares are driven by excitable dynamics triggered by stochastic events auch as stress, infection and other factors. Our minimal model, involving autoreactive and regulatory T-cells, demonstrates this concept. Autoimmune response initiates antigen-induced expansion through positive feedback, while regulatory cells counter the autoreactive cells through negative feedback. The model explains the decrease in MS relapses during pregnancy and the subsequent surge postpartum, based on lymphocyte dynamics. Additionally, it identifies potential therapeutic targets, predicting significant reduction in relapse rate from mild adjustments of regulatory T cell activity or production. These findings indicate that excitable dynamics may underlie flare-ups across various autoimmune disorders, potentially informing treatment strategies.

New Insights on the Role of pentraxin-3 in Allergic Asthma

Pentraxins are soluble pattern recognition receptors that play a major role in regulating innate immune responses. Through their interaction with complement components, Fcγ receptors, and different microbial moieties, Pentraxins cause an amplification of the inflammatory response. Pentraxin-3 is of particular interest since it was identified as a biomarker for several immune-pathological diseases. In allergic asthma, pentraxin-3 is produced by immune and structural cells and is up-regulated by pro-asthmatic cytokines such as TNFα and IL-1β. Strikingly, some recent experimental evidence demonstrated a protective role of pentraxin-3 in chronic airway inflammatory diseases such as allergic asthma. Indeed, reduced pentraxin-3 levels have been associated with neutrophilic inflammation, Th17 immune response, insensitivity to standard therapeutics and a severe form of the disease. In this review, we will summarize the current knowledge of the role of pentraxin-3 in innate immune response and discuss the protective role of pentraxin-3 in allergic asthma.

Complement Deficiencies Result in Surrogate Pathways of Complement Activation in Novel Polygenic Lupus-like Models of Kidney Injury

Lupus nephritis (LN) is a major contributor to morbidity and mortality in lupus patients, but the mechanisms of kidney damage remain unclear. In this study, we introduce, to our knowledge, novel models of LN designed to resemble the polygenic nature of human lupus by embodying three key genetic alterations: the Sle1 interval leading to anti-chromatin autoantibodies; Mfge8-/- , leading to defective clearance of apoptotic cells; and either C1q-/- or C3-/- , leading to low complement levels. We report that proliferative glomerulonephritis arose only in the presence of all three abnormalities (i.e., in Sle1.Mfge8 -/- C1q -/- and Sle1.Mfge8 -/- C3 -/- triple-mutant [TM] strains [C1q -/-TM and C3-/- TM, respectively]), with structural kidney changes resembling those in LN patients. Unexpectedly, both TM strains had significant increases in autoantibody titers, Ag spread, and IgG deposition in the kidneys. Despite the early complement component deficiencies, we observed assembly of the pathogenic terminal complement membrane attack complex in both TM strains. In C1q-/- TM mice, colocalization of MASP-2 and C3 in both the glomeruli and tubules indicated that the lectin pathway likely contributed to complement activation and tissue injury in this strain. Interestingly, enhanced thrombin activation in C3-/- TM mice and reduction of kidney injury following attenuation of thrombin generation by argatroban in a serum-transfer nephrotoxic model identified thrombin as a surrogate pathway for complement activation in C3-deficient mice. These novel mouse models of human lupus inform the requirements for nephritis and provide targets for intervention.

Antibodies targeting circulating protective molecules in lupus nephritis: Interest as serological biomarkers

Lupus nephritis (LN) is one of the most frequent and severe manifestations of systemic lupus erythematosus (SLE), considered as the major predictor of poor prognosis. An early diagnosis of LN is a real challenge in the management of SLE and has an important implication in guiding treatments. In clinical practice, conventional parameters still lack sensitivity and specificity for detecting ongoing disease activity in lupus kidneys and early relapse of nephritis. LN is characterized by glomerular kidney injury, essentially due to deposition of immune complexes involving autoantibodies against cellular components and circulating proteins. One of the possible mechanisms of induction of autoantibodies in SLE is a defect in apoptotic cells clearance and subsequent release of intracellular autoantigens. Autoantibodies against soluble protective molecules involved in the uptake of dying cells, including complement proteins and pentraxins, have been described. In this review, we present the main autoantibodies found in LN, with a focus on the antibodies against these protective molecules. We also discuss their pathogenic role and conclude with their potential interest as serological biomarkers in LN.

Complement in removal of the dead - balancing inflammation

Recognition and removal of apoptotic and necrotic cells must be efficient and highly controlled to avoid excessive inflammation and autoimmune responses to self. The complement system, a crucial part of innate immunity, plays an important role in this process. Thus, apoptotic and necrotic cells are recognized by complement initiators such as C1q, mannose binding lectin, ficolins, and properdin. This triggers complement activation and opsonization of cells with fragments of C3b, which enhances phagocytosis and thus ensures silent removal. Importantly, the process is tightly controlled by the binding of complement inhibitors C4b-binding protein and factor H, which attenuates late steps of complement activation and inflammation. Furthermore, factor H becomes actively internalized by apoptotic cells, where it catalyzes the cleavage of intracellular C3 to C3b. The intracellularly derived C3b additionally opsonizes the cell surface further supporting safe and fast clearance and thereby aids to prevent autoimmunity. Internalized factor H also binds nucleosomes and directs monocytes into production of anti-inflammatory cytokines upon phagocytosis of such complexes. Disturbances in the complement-mediated clearance of dying cells result in persistence of autoantigens and development of autoimmune diseases like systemic lupus erythematosus, and may also be involved in development of age-related macula degeneration.

To Evaluate and Compare Periodontal Disease and Smoking as a Parallel Risk Factor for Systemic Health by Gauging the Serum C-Reactive Protein Levels

INTRODUCTION

Physiologic and metabolic changes that occur immediately after a damage or disease are known as Acute Phase Reaction (APR). Acute Phase Proteins (APP) are blood proteins secreted by hepatocytes during APR C-Reactive Protein (CRP) being the important one.

AIM

Present study was designed to estimate and compare the levels of the serum CRP in current smokers, former smokers and non-smokers, with and without periodontitis.

MATERIALS AND METHODS

An experimental study was planned on 165 subjects who were divided into four groups. Group 1- nonsmokers with periodontitis. Group 2- smokers without periodontitis. Group 3- smokers with periodontitis. Group 4- former smokers without periodontitis. Healthy controls were not included in the study as the normal range of CRP in health is already established. Periodontal examination was done and serum CRP was measured. After getting the acceptance to be a part of the study, written informed consent was taken from each participant. Data analysis was done by ANOVA and post-hoc tests.

RESULTS

Highest level of CRP was found in smokers with periodontitis followed by non-smokers with periodontitis and smokers without periodontitis. Former smokers had minimum CRP compared to the other groups (p-value=0.03).

CONCLUSION

Periodontitis alone and in combination with smoking increases the systemic inflammatory burden and associated cardiovascular risk. This fact should be communicated thoroughly to the general population, general dentist, physicians and cardiovascular specialist to enhance early screening and multidisciplinary treatment.

Anti-C1q autoantibodies are linked to autoimmune thyroid disorders in pregnant women

Anti-C1q antibodies (anti-C1q) have been implicated in the pathogenesis of autoimmune diseases, including autoimmune thyroid disorders (AITD). The aim of this study was to evaluate the association between anti-C1q and thyroid function in pregnancy-associated AITD. In 96 pregnant women screened positive for AITD (thyroid dysfunction and/or antibodies against thyroperoxidase - TPOAb), anti-C1q were measured during the 9-11th gestational week and after delivery (median 16 months after delivery), and compared to the corresponding serum levels of thyroid hormones. As controls, 80 healthy pregnant women, 72 non-pregnant AITD patients and 72 blood donors were included. In the non-pregnant AITD group, two serum samples ≥ 6 months apart were analysed. Compared to blood donors, anti-C1q levels were substantially higher in all pregnant women analysed. In pregnancy, anti-C1q levels were higher in the TPOAb-positive women than in controls (37 versus 17·5%, P < 0·0001). Anti-C1q-positive pregnant women screened positive for AITD had higher thyroid-stimulating hormone (TSH) levels than anti-C1q-negative women (2·41 versus 1·94 mU/l, P = 0·01), and TSH correlated positively with anti-C1q (r = 0·226, P = 0·045) in the TPOAb-positive women. After delivery, serum levels of anti-C1q decreased in the positively screened TPOAb-negative women (8·8 versus 5·9 U/l, P = 0·002), but not in the TPOAb-positive ones, and they no longer correlated with TSH. Anti-C1q antibody levels increase during pregnancy in general and even more in the context of AITD, where they correlate with thyroid stimulating hormone levels.

Pharmacokinetics and concentration-effect relationship of adalimumab in rheumatoid arthritis

AIMS

This study aimed at describing adalimumab pharmacokinetics (PK) and the concentration-effect relationship of adalimumab using pharmacokinetic-pharmacodynamic (PK-PD) modelling in patients with rheumatoid arthritis (RA).

METHODS

Adalimumab PK and PK-PD data were obtained from a multicentric observational study. Adalimumab (40 mg) was administered subcutaneously every other week, and its pharmacokinetics was described using a one-compartment model. The relationship between adalimumab concentration and C-reactive protein (CRP) concentration was described using an indirect response model with inhibition of CRP input, whereas the relationship between adalimumab concentration and disease activity score in 28 joints (DAS28) was described using a direct inhibition model. Dose regimens that included a loading dose of adalimumab were simulated.

RESULTS

Thirty patients treated for RA were analysed. The following pharmacokinetic and PK-PD parameters were estimated (interidividual coefficient of variation): apparent volume of distribution (Vd /F) = 10.8 l (92%); apparent clearance (CL/F) = 0.32 l day(-1) (17%); first-order absorption rate (ka ) = 0.28 day(-1) ; CRP input (kin ) = 22.0 mg l(-1)  day(-1) (65%); adalimumab concentration leading to a 50% decrease in kin (C50 ) = 3.6 mg l(-1) (88%); baseline DAS28 (DAS0 ) = 5.5 mg l(-1) (11%); and adalimumab concentration leading to 50% decrease of DAS0 (IC50 ) = 11.0 mg l(-1) (71%). Simulations showed that a 160 mg loading dose should reduce the time to reach efficacy in terms of both CRP and DAS28 after the first injection.

CONCLUSIONS

This is the first study to describe adalimumab pharmacokinetics and the concentration-effect relationship in RA. A 160 mg loading dose may lead to an increased benefit from treatment in RA patients.

Inflammatory etiopathogenesis of systemic lupus erythematosus: an update

The immune system struggles every day between responding to foreign antigens and tolerating self-antigens to delicately maintain tissue homeostasis. If self-tolerance is broken, the development of autoimmunity can be the consequence, as it is in the case of the chronic inflammatory autoimmune disease systemic lupus erythematosus (SLE). SLE is considered to be a multifactorial disease comprising various processes and cell types that act abnormally and in a harmful way. Oxidative stress, infections, or, in general, tissue injury are accompanied by massive cellular demise. Several processes such as apoptosis, necrosis, or NETosis (formation of Neutrophil Extracellular Traps [NETs]) may occur alone or in combination. If clearance of dead cells is insufficient, cellular debris may accumulate and trigger inflammation and leakage of cytoplasmic and nuclear autoantigens like ribonucleoproteins, DNA, or histones. Inadequate removal of cellular remnants in the germinal centers of secondary lymphoid organs may result in the presentation of autoantigens by follicular dendritic cells to autoreactive B cells that had been generated by chance during the process of somatic hypermutation (loss of peripheral tolerance). The improper exposure of nuclear autoantigens in this delicate location is consequently prone to break self-tolerance to nuclear autoantigens. Indeed, the germline variants of autoantibodies often do not show autoreactivity. The subsequent production of autoantibodies plays a critical role in the development of the complex immunological disorder fostering SLE. Immune complexes composed of cell-derived autoantigens and autoantibodies are formed and get deposited in various tissues, such as the kidney, leading to severe organ damage. Alternatively, they may also be formed in situ by binding to planted antigens of circulating autoantibodies. Here, we review current knowledge about the etiopathogenesis of SLE including the involvement of different types of cell death, serving as the potential source of autoantigens, and impaired clearance of cell remnants, causing accumulation of cellular debris.

Incomplete clearance of apoptotic cells in systemic lupus erythematosus: pathogenic role and potential biomarker

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with repeated inflammation against multiple organs. Although its pathophysiology is not yet unveiled, uncleared apoptotic cells and their accumulation in tissue contribute to the autoimmune disturbance in SLE. Apoptosis is a programmed cell death process, which maintains tissue homeostasis and inhibits the development of any further immune response against apoptotic remnants. Earlier studies revealed that various 'eat-me' signals on apoptotic cells, bridging molecules and their receptors on phagocytes play a role in such a complicated process. Tyro3-Axl-Mer receptors, their bridging molecules, milk fat globulin epidermal growth factor-8, T-cell immunoglobulin mucin domain protein family, scavenger receptors, C1q, and pentraxins were found to be abnormal in SLE. In this review, apoptosis and clearance of its remnants are summarized, and the molecules involved in the incomplete clearance of apoptotic cells in SLE are discussed.

C-Reactive Protein (CRP) and its Association with Periodontal Disease: A Brief Review

Periodontal disease is a chronic infection of the gums characterised by a loss of attachment between the tooth and bone, and bone loss. C-reactive protein (CRP) elevation is a part of the acute phase response to acute and chronic inflammation. Many epidemiological studies have shown that serum CRP levels were elevated in patients with chronic periodontitis. CRP levels increase to hundreds of μg/ml within hours following infection. It out-performs erythrocyte sedimentation rate (ESR) in terms of responsiveness and specificity for inflammation. While CRP elevation is suggestive of inflammation or infection in the appropriate clinical context, it can also occur with obesity and renal dysfunction. Conversely, a lack of CRP elevation in inflammation may be seen with hepatic failure, as well as during flares of conditions such as systemic lupus erythematosus.

Plasma soluble urokinase plasminogen activator receptor (suPAR) levels in systemic lupus erythematosus

OBJECTIVE

Soluble urokinase plasminogen activator receptor (suPAR) is a biomarker of systemic inflammation. We aimed to characterize plasma suPAR levels in SLE patients.

METHODS

We measured plasma suPAR, C reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in 89 SLE patients and 29 healthy controls.

RESULTS

suPAR and ESR values were higher in SLE than in controls, while CRP levels were comparable. ROC analysis of suPAR levels indicated a cut-off value of 5.70 ng/mL to distinguish patients with high disease activity (SLEDAI >8).

CONCLUSION

suPAR might be an objective marker for identifying SLE patients with active disease.

Biochemical analysis of the epitope specificities of anti-C1q autoantibodies accompanying human lupus nephritis reveals them as a dynamic population in the course of the disease

We analyzed the epitope specificities of the polyclonal anti-C1q antibodies, present in human LN sera, searching to deduce the structural characteristics of C1q associated with its transition to an autoantigen. We screened 78 serum samples from LN patients distributed in three clinical groups - non-active, moderately active and severely active. We found three classes of C1q autoepitopes: (a) neo-epitopes, exposed upon immobilization due to conformational changes; (b) epitopes formed by sequences that are brought together by the conformation of the whole molecule; (c) cryptic epitopes that become exposed only after fragmentation of C1q. The latter suggest that the immunogen involved in the initiation of anti-C1q autoantibodies might be an extrinsic molecule that shares some degree of structural similarity to C1q. None of the tested epitope specificities was associated with active LN. We found a prevalence of anti-gC1q antibodies among the non-active LN patients suggesting that they might be the fraction of the polyclonal anti-C1q, preceding the initiation of autoimmunity to C1q, or alternatively, preceding LN flare.

Long pentraxin 3 (PTX3) in the light of its structure, mechanism of action and clinical implications

Pentraxins are a group of evolutionarily conserved ancient proteins. Depending on their structure, pentraxins are divided into short and long pentraxin families. Pentraxin 3 (PTX3) is the prototype of the long pentraxin group. PTX3 synthesis is stimulated by a variety of molecules involved in the inflammatory process. The inflammatory mediator is typically produced at inflammatory sites; however, it can also be released at the sites remote from the original inflammatory insult. Although mainly expressed by vascular endothelium and smooth muscle cells, PTX3 is also synthesized by myeloid dendritic cells, mononuclear macrophages/phagocytes, vascular endothelial and smooth muscle cells, fibroblasts, adipocytes, cumulus oophorus cells mesangial cells, synovial cells and chondrocytes. PTX3 binds to several ligands including complement component C1q, factor H, ficolin-1 (M-ficolin), mannose-binding lectin, fibroblast growth factor 2, P-selectin, matrix protein TSG6 and Klebsiella pneumoniae; it is also known to play a role in humoral innate immunity as well as in degenerated and apoptotic cells clearance. PTX3 acts as a modulator of inflammatory processes, modifies angiogenesis and atherosclerotic lesion development, and participates in extracellular matrix formation. Due to the fact of PTX3 being primarily produced and released by vascular wall cells, it might be used as a sensitive and independent inflammatory marker.

Functional complement C1q abnormality leads to impaired immune complexes and apoptotic cell clearance

C1q plays a key role in apoptotic cell and immune complex removal. Its absence contributes to the loss of tolerance toward self structures and development of autoimmunity. C1q deficiencies are extremely rare and are associated with complete lack of C1q or with secretion of surrogate C1q fragments. To our knowledge, we report the first case of a functional C1q abnormality, associated with the presence of a normal C1q molecule. Homozygous GlyB63Ser mutation was found in a patient suffering from lupus with neurologic manifestations and multiple infections. The GlyB63Ser C1q bound to Igs, pentraxins, LPSs, and apoptotic cells, similarly to C1q from healthy donors. However, the interaction of C1r(2)C1s(2) and C1 complex formation was abolished, preventing further complement activation and opsonization by C3. The mutation is located between LysB(61) and LysB(65) of C1q, suggested to form the C1r binding site. Our data infer that the binding of C1q to apoptotic cells in humans is insufficient to assure self-tolerance. The opsonization capacity of C4 and C3 fragments has to be intact to fight infections and to prevent autoimmunity.

New insight into the autoimmunogenicity of the complement protein C1q

C1q along with its physiological role in maintenance of homeostasis and normal function of the immune system is involved in pathological conditions associated with repetitive generation of anti-C1q autoantibodies. The time and events that cause their first appearance are still unknown. We addressed this issue by analyzing the immunogenicity of C1q in two target groups-one of non-diseased humans and the other of lupus nephritis (LN) patients whose autoimmune disorder is associated with high titers of anti-C1q autoantibodies. The non-diseased humans were represented by pregnant women because the sex hormones are thought to be involved in triggering autoimmune pathologies by their ability to tip the balance of female adaptive immune response to production of antibodies. We screened, using ELISA, 31 sera from healthy pregnant women for the presence of IgM and IgG classes of autoantibodies, recognizing epitopes within the native C1q molecule, its collagen-like region (CLR) and globular head fragment (gC1q). The latter was represented by recombinant analogs of the three globular fragments of A, B and C chains, comprising C1q-ghA, ghB and ghC. We did not find IgM antibodies for all test-antigens which suggest that the natural IgM antibodies are not involved in triggering autoimmunity to C1q. Still more, we did not detect anti-CLR antibodies which have been proved pathogenic in already manifested LN. We completed the analysis with comparative epitope mapping of gC1q and we found similar immunogenic behavior in both target groups-ghA and ghC contained the immunodominant epitopes. This implies that the initial immune response to C1q might occur when the molecule has interacted with its ligands via ghB as part of gC1q. The presence of anti-gC1q in both healthy and diseased humans also implies that these antibodies, unlike anti-CLR, may have a contribution to an onset of autoimmunity.

Protective molecules and their cognate antibodies: new players in autoimmunity

Impairment of the clearance of apoptotic material seems to contribute to autoantigen exposure, which can initiate or maintain an autoimmune response in predisposed individuals. Complement component C1q, Creactive protein (CRP), serum amyloid P (SAP), mannose-binding lectin (MBL), apolipoprotein A-1 (Apo A-1) and long pentraxin 3 (PTX3) are molecules involved in the removal of apoptotic bodies and pathogens, and in other antiinflammatory pathways. For this reason they have been called "protective" molecules. C1q has a key role in the activation of the complement cascade and acts as a bridging molecule between apoptotic bodies and macrophages favouring phagocytosis. In addition to other functions, CRP, SAP and MBL bind to the surface of numerous pathogens as well as cellular debris and activate the complement cascade, thus stimulating their clearance by immune cells. The role of PTX3 is more controversial. In fact, PTX also promotes the clearance of microorganisms, but the activation of the complement cascade through C1q and removal of apoptotic material can be either stimulated or inhibited by this molecule. Antibodies against protective molecules have been recently reported in systemic lupus erythematosus and other autoimmune rheumatic diseases. Some of them seem to be pathogenetic and others protective. Thus, protective molecules and their cognate antibodies may constitute a regulatory network involved in autoimmunity. Dysregulation of this system might contribute to the development of autoimmune diseases in predisposed individuals.

Pentraxins, anti-pentraxin antibodies, and atherosclerosis

Atherosclerosis is a disease of the vascular wall, which predominantly affects large and medium-sized arteries. It represents a leading cause of morbidity and mortality in the Western world. In the last few decades, it has been clearly shown that immune system plays a relevant role in atherogenesis. The effectors of both innate and adaptive immunity, including immune cells, cell or soluble receptors, cytokines, chemokines, complement components or coagulation systems, and autoantibodies are able to modulate atherosclerosis. Among proteins belonging to innate immunity, the highly conserved pentraxin family, which encompass C-reactive protein (CRP), serum amyloid P (SAP), and the long pentraxin 3 (PTX3) seems to be directly involved in the induction and progression of atherosclerosis. By immunohistochemical staining, pentraxins were found within the atherosclerotic plaques where they could play a key role interacting with atherogenic-modified lipoproteins, favoring the formation of foam cells, and exerting a proinflammatory action. Pentraxin serum levels have been shown to be associated with clinical and subclinical atherosclerosis in general population. Antibodies against pentraxins have been demonstrated in patients with autoimmune diseases, but their role in atherogenesis is still controversial.

Serum amyloid A and C-reactive protein concentrations are differently associated with markers of autoimmunity in patients with primary Sjögren's syndrome

OBJECTIVE

Primary Sjögren's syndrome (pSS) is an autoimmune disease in which the concentration of the acute-phase protein serum C-reactive protein (CRP) is low. We investigated whether levels of another acute-phase protein, serum amyloid A (SAA), are increased in patients with pSS and whether the immunological markers in patients with pSS are associated with variation in SAA levels.

METHODS

Serum SAA concentrations were measured by ELISA in 74 patients with pSS and in 56 control subjects with sicca symptoms.

RESULTS

Median SAA levels did not differ significantly between patients with pSS and subjects with sicca symptoms. In patients with pSS SAA concentrations correlated significantly with age, leukocyte count, CRP, interleukin 6, and C4. Unlike CRP, there was a significant inverse correlation between SAA and serum IgG levels and anti-SSA antibody titers, as well as a trend towards an inverse correlation between SAA and antinuclear antibody and rheumatoid factor titers.

CONCLUSION

Our data imply that high SAA production could constitute a protective element in pSS: high SAA levels inhibit in particular various signs of B cell hyperreactivity, i.e., IgG and autoantibody production.

Increased Serum Pentraxin 3 in Patients with Systemic Sclerosis

Objective.

To determine serum concentrations of pentraxin 3 (PTX3) and its clinical associations in patients with systemic sclerosis (SSc).

Methods.

Serum PTX3 levels from 45 patients with diffuse cutaneous SSc (dSSc), 46 with limited cutaneous SSc (lSSc), and 20 healthy controls were examined by ELISA. PTX3 expression in the sclerotic skin from SSc patients was evaluated immunohistochemically. Normal and SSc fibroblasts were cultured and PTX3 levels in the culture medium were also examined by ELISA.

Results.

Serum PTX3 levels were elevated in patients with SSc relative to controls. PTX3 levels in dSSc patients were significantly higher than in controls and lSSc patients. PTX3 expression in the sclerotic skin from SSc patients was more intense relative to normal skin. Elevation of serum PTX3 levels was associated with more frequent presence of pulmonary fibrosis, cardiac disease, and pitting scar/ulcer and increased serum immunoglobulin levels and erythrocyte sedimentation rates. PTX3 levels correlated positively with modified Rodnan total skin thickness score, and negatively with percentage vital capacity and percentage DLCO in patients with SSc. PTX3 levels also correlated positively with serum levels of 8-isoprostane, a marker of oxidative stress, and hyaluronan, recently identified as an endogenous ligand for Toll-like receptors. PTX3 production from cultured SSc fibroblasts was increased by stimulation with hyaluronan.

Conclusion

These results suggest that elevated serum PTX3 levels are associated with the disease severity of SSc.

Plasma Pentraxin3 is a novel marker for nonalcoholic steatohepatitis (NASH)

Background

The changes in the liver in nonalcoholic fatty liver disease (NAFLD) range over a wide spectrum, extending from steatosis to steatohepatitis (NASH). However it has remained difficult to differentiate between NASH and non-progressive NAFLD on the basis of the clinical findings alone.

Aims

In this study we investigated the clinical usefulness of plasma Pentraxin3 (PTX3) levels to predict NASH. Plasma PTX3 was measured in 70 patients with histologically verified NAFLD (28 with non-NASH and 42 with NASH) and 10 healthy control subjects.

Results

The plasma PTX3 level was significantly higher in the NASH cases than in the non-NASH cases (p = 0.0021) and control subjects (p = 0.045). And the plasma PTX3 level was significantly higher in the stages 3–4 NAFLD cases than in the stages 0–2 NAFLD cases (p < 0.0001). The PTX3 values were closely correlated with the stages of liver fibrosis (p < 0.0001, Kruskal-Wallis test). To detect NASH compared with non-NASH, the area under the curve for plasma PTX3 were 0.755, and to detect stages 3–4 NAFLD compared with stages 0–2 NAFLD, the area under the curve for plasma PTX3 were 0.850.

Conclusion

This is the first study to demonstrate consistent and profound elevation of plasma PTX3 levels in NASH in comparison with non-NASH. The results suggest that plasma PTX3 levels may not only be laboratory values that differentiate NASH from non-NASH, but marker of the severity of hepatic fibrosis in NASH.

The long pentraxin 3 and its role in autoimmunity

OBJECTIVES

To review the physiological and physiopathological roles of pentraxin 3 (PTX3), focusing on autoimmunity and vascular pathology.

METHODS

A systematic literature review using the keywords "pentraxin 3," "innate immunity," "apoptosis," "autoimmunity," and "endothelial dysfunction" from 1990 to 2007 was performed. All relevant articles and pertinent secondary references in English were reviewed.

RESULTS

PTX3 has a large number of multiple functions in different contexts. PTX3 plays an important role in innate immunity, inflammation, vascular integrity, fertility, pregnancy, and also in the central nervous system. In innate immunity, its normal function is to increase the immune response to selected pathogens while also exerting control over potential autoimmune reactions. It maintains a tightly homeostatic equilibrium in the local immune microenvironment by avoiding an exaggerated immune response and controlling peripheral tolerance to self-antigens. In contrast, in some autoimmune diseases, PTX3 appears to be involved in the development of autoimmune phenomena. A possible explanation for these apparent paradoxical functions may be related to the highly polymorphic PTX3 gene.

CONCLUSION

PTX3 is physiologically a protective molecule. However, in several autoimmune diseases PTX3 appears to facilitate the development of autoimmunity. The PTX3 gene could influence the development of autoimmune reactions and vascular involvement in human pathology.

Altered systemic serologic parameters in patients with silicone mammary implants

BACKGROUND

The most common local complication in patients with silicone mammary implants (SMIs) is excessive peri-SMI connective tissue capsule formation and its subsequent contracture. However, considerable controversy remains as to whether these implants also cause systemic side effects. The present study was undertaken to identify possible alterations of serological markers in SMI patients that may herald systemic side effects.

METHODS

We investigated several systemic serological parameters in 143 individuals, 93 of whom had received SMIs and 50 were controls. The patients were grouped according to the severity of capsular contracture (Baker scores I-IV) and the duration of SMI implants (less than 1 year, between 1 and 5 years, more than 5 years). We also included control groups (female blood donors, nurses with possible professional silicone exposure). Patients with breast cancer and subsequent SMI-reconstruction were excluded from the study since they are generally considered immunocompromised. The following parameters were determined: anti-neutrophil cytoplasmatic autoantibodies (cANCA), anti-nuclear autoantibodies (ANA), anti-cardiolipin antibodies (CL-Ab), rheumatoid factor (RF), complement components (C3, C4), circulating immune complexes (CIC), procollagen III (a marker of active fibrosis), anti-polymer antibodies (APA) and soluble intercellular adhesion molecule-1 (sICAM-1).

RESULTS

The following parameters were increased in the sera of SMI patients: CIC, procollagen III, APA, sICAM-1.

CONCLUSIONS

We found a set of parameters in serum that correlate with fibrosis development and the duration of the implants in otherwise healthy SMI carriers. Future studies will clarify whether these serological abnormalities will be useful in predicting clinical disease, and also further assess the sensitivity and specificity of these parameters. Our present recommendation as a result of this study is that SMI patients with persistent abnormal serological parameters should be monitored closely by a clinical team that includes rheumatologists.

Rheumatic fever: from innate to acquired immune response

Rheumatic fever (RF) is triggered by S. pyogenes and affects 3-4% of untreated susceptible children. The immune response against streptococcal antigens can lead cross-recognition of heart tissue proteins resulting in rheumatic heart disease (RHD). HLA class II alleles have been associated with the development of RF/RHD. Tumor necrosis factor (TNF)-alpha is also located in the same chromosomal region of HLA genes and has been investigated in RHD patients from Mexico, Turkey, and Brazil. Associations with the TNFA-308 allele were found and probably are related to the development of valvular lesions. A deficient mannose-binding lectin (MBL) allele was found in Brazilian patients. MBL is a protein important for the first line of host defense against the bacteria. The association with diverse genes probably indicates a role of certain molecules in both the innate and adaptive immune response. Antigen-presenting cells bearing the HLA-DR7 molecule from RHD patients preferentially recognized a heart-tissue protein cross-reactive M5 (81-96) peptide. The same peptide was also recognized by heart tissue T cell clones. Cardiac myosin peptides were recognized by high numbers of intralesional T cell clones. The cytokine pattern of infiltrating mononuclear cells in both myocardium and valvular tissue showed a predominance of proinflammatory cytokines (TNF-alpha and IFN-gamma) and scarce production of regulatory cytokines, such as IL-4, in the valve tissue. IL-10, a predominant regulatory cytokine, was also secreted by large numbers of cells in both valve and myocardium tissue. Data here indicate the complexity of immune reactions leading to autoimmune lesions in RF/RHD.

Autoantibodies against Protective Molecules C1q, C-Reactive Protein, Serum Amyloid P, Mannose-Binding Lectin, and Apolipoprotein A1: Prevalence in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of several autoantibodies. Among the multiple factors involved in SLE development, apoptotic defects and impaired clearance of cellular debris have gained considerable interest, as they contribute to autoantigen overload. Several molecules of the innate immunity, also participate in the removal of damaged and apoptotic cells. Among them are C1q, C-reactive protein (CRP), serum amyloid P protein (SAP), mannose-binding lectin (MBL), and apolipoprotein A1 (APO A1). To evaluate the prevalence of autoantibodies against CRP, SAP, MBL, APO A1, and C1q among SLE patients, and their relationship with disease activity, a total of 150 SLE patients were screened for the presence of elevated antibody titers against C1q, CRP, SAP, MBL, and APO A1, utilizing the enzyme-linked immunosorbent assay (ELISA) method. Disease activity was assessed using the ECLAM or SLEDAI scores. The study population comprised two groups of patients: 100 patients with quiescent disease (median ECLAM score 2) comprised the first group, and 50 patients with active disease (median SLEDAI score 16) comprised group 2. Elevated titers of anti-CRP antibodies were significantly elevated only in group 1 (10% versus 4% of controls). Antibodies against SAP were evaluated only among patients in group 1, and were found at a significant high prevalence (20%). Elevated titers of anti-MBL antibodies were significantly elevated only in group 1 (15% versus 3.6%); and antibodies directed against APO A1 were significantly elevated in 21% of group 1, and 50% of group 2 patients. Elevated titers of anti-C1q were evaluated only in group 2, and were found at a significant prevalence of 66%. Significant correlation with disease activity was found only for anti-APO A1 antibodies, and only in group 1. Several patients harbored more than one of the autoantibodies tested. In patients with SLE, autoantibodies directed against protective molecules, that is, acute-phase proteins involved in the disposal of cellular and nuclear debris, can be detected. These autoantibodies may play a pathogenic role in the development or perpetuation of autoimmunity in SLE.

Pathogenic implications for autoantibodies against C-reactive protein and other acute phase proteins

Systemic lupus erythematosus (SLE) is a systemic rheumatic disease characterized clinically by multiorgan involvement and serologically by the occurrence of antinuclear antibodies. SLE patients may present with multiple autoantibodies to cytoplasmic and cell surface antigens as well as to circulating plasma proteins. Another feature of SLE is that serum levels of C-reactive protein (CRP) often remain low despite high disease activity and despite high levels of other acute phase proteins and interleukin-6, i.e. the main CRP inducing cytokine. Apart from its important role as a laboratory marker of inflammation, CRP attracts increasing interest due to its many intriguing biological functions, one of which is a role as an opsonin contributing to the elimination of apoptotic cell debris, e.g. nucleosomes, thereby preventing immunization against autoantigens. Recently, autoantibodies against CRP and other acute phase proteins have been reported in certain rheumatic conditions, including SLE. Although the presence of anti-CRP autoantibodies does not explain the failed CRP response in SLE, antibodies directed against acute phase proteins have several implications of pathogenetic interest. This paper thus highlights the biological and clinical aspects of native and monomeric CRP and anti-CRP, as well as autoantibodies against mannose-binding lectin, serum amyloid A and serum amyloid P component.