Anti-phosphorylcholine Antibodies Research Articles

Marginal zone B cells produce 'natural' atheroprotective IgM antibodies in a T cell-dependent manner.

The adaptive immune response plays an important role in atherosclerosis. In response to a high-fat/high-cholesterol (HF/HC) diet, marginal zone B (MZB) cells activate an atheroprotective programme by regulating the differentiation and accumulation of 'poorly differentiated' T follicular helper (Tfh) cells. On the other hand, Tfh cells activate the germinal centre response, which promotes atherosclerosis through the production of class-switched high-affinity antibodies. We therefore investigated the direct role of Tfh cells and the role of IL18 in Tfh differentiation in atherosclerosis. We generated atherosclerotic mouse models with selective genetic deletion of Tfh cells, MZB cells, or IL18 signalling in Tfh cells. Surprisingly, mice lacking Tfh cells had increased atherosclerosis. Lack of Tfh not only reduced class-switched IgG antibodies against oxidation-specific epitopes (OSEs) but also reduced atheroprotective natural IgM-type anti-phosphorylcholine (PC) antibodies, despite no alteration of natural B1 cells. Moreover, the absence of Tfh cells was associated with an accumulation of MZB cells with substantially reduced ability to secrete antibodies. In the same manner, MZB cell deficiency in Ldlr-/- mice was associated with a significant decrease in atheroprotective IgM antibodies, including natural anti-PC IgM antibodies. In humans, we found a positive correlation between circulating MZB-like cells and anti-OSE IgM antibodies. Finally, we identified an important role for IL18 signalling in HF/HC diet-induced Tfh. Our findings reveal a previously unsuspected role of MZB cells in regulating atheroprotective 'natural' IgM antibody production in a Tfh-dependent manner, which could have important pathophysiological and therapeutic implications.

Higher levels of anti-phosphorylcholine autoantibodies in early rheumatoid arthritis indicate lower risk of incident cardiovascular events

BackgroundThe increased risk of cardiovascular events (CVE) in rheumatoid arthritis (RA) is not fully explained by traditional risk factors. Immuno-inflammatory mechanisms and autoantibodies could be involved in the pathogenesis of atherosclerotic disease. It has been suggested that anti-phosphorylcholine antibodies (anti-PC) of the IgM subclass may have atheroprotective effects. Here, we aimed to investigate the association between levels of IgM anti-PC antibodies with CVE in patients with early RA.MethodsThe study population was derived from the BARFOT early RA cohort, recruited in 1994–1999. The outcome of incident CVE (AMI, angina pectoris, coronary intervention, ischemic stroke, TIA) was tracked through the Swedish Hospital Discharge and the National Cause of Death Registries. Sera collected at inclusion and the 2-year visit were analyzed with ELISA to determine levels of anti-PC IgM. The Kaplan-Meier estimates and Cox proportional hazards regression models were used to compare CV outcome in the groups categorized by baseline median level of IgM anti-PC.ResultsIn all, 653 patients with early RA, 68% women, mean (SD) age 54.8 (14.7) years, DAS28 5.2 (1.3), 68% seropositive, and without prevalent CVD, were included. During the follow-up of mean 11.7 years, 141 incident CVE were recorded.Baseline IgM anti-PC above median was associated with a reduction in risk of incident CVE in patients aged below 55 years at inclusion, HR 0.360 (95% CI, 0.142–0.916); in males, HR 0.558 (0.325–0.958); in patients with BMI above 30 kg/m2, HR 0.235 (0.065–0.842); and in those who did not achieve DAS28 remission at 1 year, HR 0.592 (0.379–0.924). The pattern of associations was confirmed in the models with AUC IgM anti-PC over 2 years.ConclusionProtective effects of higher levels of innate IgM anti-PC autoantibodies on CVE were detected in younger patients with RA and those at high risk of CVE: males, presence of obesity, and non-remission at 1 year.

The Influence of a Conjugated Pneumococcal Vaccination on Plasma Antibody Levels against Oxidized Low-Density Lipoprotein in Metabolic Disease Patients: A Single-Arm Pilot Clinical Trial.

As a mediator between lipid metabolism dysfunction, oxidative stress and inflammation, oxidized low-density lipoprotein (oxLDL) is a promising therapeutical target in a wide range of metabolic diseases. In mice, pneumococcal immunization increases anti-phosphorylcholine and oxLDL antibody levels, and reduces atherosclerosis, non-alcoholic steatohepatitis and Niemann–Pick disease burden. These findings suggest that pneumococcal vaccination may be a useful preventive and therapeutical strategy in metabolic disease patients. In this pilot clinical trial, our aim was to determine whether the administration of a pneumococcal vaccine increases anti-phosphorylcholine and anti-oxLDL antibody levels in metabolic disease patients. The following patients were enrolled: four patients with familial partial lipodystrophy (all women, mean age 32 years old); three familial hypercholesterolemia patients (one girl, two boys; mean age 13 years); and two Niemann–Pick type B (NP-B) patients (two men, mean age 37.5 years old). Participants received one active dose of a 13-valent conjugated pneumococcal vaccine (Prevenar 13) and were followed-up for four weeks. Four weeks after Prevenar 13 vaccination, no differences were observed in patients’ levels of anti-oxLDL IgM or IgG antibodies. In addition, we observed a reduction in anti-phosphorylcholine (anti-PC) IgM antibody levels, whereas no differences were observed in anti-PC IgG antibody titers. These findings indicate that Prevenar 13 vaccination does not induce an immune response against oxLDL in patients with metabolic diseases. Therefore, Prevenar 13 is not suited to target the metabolic disruptor and pro-inflammatory mediator oxLDL in patients.

Zwitterionic Phosphodiester-Substituted Neoglycoconjugates as Ligands for Antibodies and Acute Phase Proteins.

Zwitterionic modifications of glycans, such as phosphorylcholine and phosphoethanolamine, are known from a range of prokaryotic and eukaryotic species and are recognized by mammalian antibodies and pentraxins; however, defined saccharide ligands modified with these zwitterionic moieties for high-throughput studies are lacking. In this study, we prepared and tested example mono- and disaccharides 6-substituted with either phosphorylcholine or phosphoethanolamine as bovine serum albumin neoglycoconjugates or printed in a microarray format for subsequent assessment of their binding to lectins, pentraxins, and antibodies. C-Reactive protein and anti-phosphorylcholine antibodies bound specifically to ligands with phosphorylcholine, but recognition by concanavalin A was abolished or decreased as compared with that to the corresponding nonzwitterionic compounds. Furthermore, in array format, the phosphorylcholine-modified ligands were recognized by IgG and IgM in sera of either non-infected or nematode-infected dogs and pigs. Thereby, these new compounds are defined ligands which allow the assessment of glycan-bound phosphorylcholine as a target of both the innate and adaptive immune systems in mammals.

IgM anti-phosphorylcholine antibodies associate with senescent and IL-17+ T cells in SLE patients with a pro-inflammatory lipid profile.

The aim was to evaluate whether T cell subsets and the lipid profile could be linked to the cardioprotective effect of IgM anti-phosphorylcholine (PC) antibodies in SLE. Anti-PC antibodies were quantified by ELISA in 197 patients and 99 controls and analysed in relationship to clinical features, treatments and serum lipids. Carotid atheromatosis was evaluated by ultrasonography; Th1, Th17, Treg and CD4+CD28null cells by flow cytometry; and cytokine serum levels by immunoassays, in a subgroup of 120 SLE patients and 33 controls. IgM anti-PC serum levels were reduced in SLE patients compared with controls (P < 0.001) and were associated with age (β= -0.252; P = 0.002), high-density lipoprotein (HDL; β = 0.271; P = 0.001), low-density lipoprotein (LDL; β= -0.192; P = 0.017) and glucocorticoid treatment (β= -0.201; P = 0.012), whereas the IgG-to-IgM anti-PC ratio was increased (P = 0.007) and associated with age (β = 0.194; P = 0.028) and SLEDAI (β = 0.250; P = 0.005). Also, patients with clinical or subclinical cardiovascular disease exhibited reduced IgM anti-PC levels compared with their cardiovascular disease-free counterparts, regardless of glucocorticoid usage (P = 0.001). CD4+CD28null and Th17 cells were increased in SLE patients compared with controls (P < 0.01) and correlated inversely with IgM anti-PC levels. These associations were observed in patients displaying high triglyceride or low HDL levels, even after adjusting for clinical parameters and treatments (CD4+CD28null: β = -0.455, P = 0.001; Th17: β= -0.280, P = 0.035), but not in those with a normal lipid profile. High triglyceride and low HDL profiles were related to low IgM anti-PC and Treg levels, respectively, whereas both lipid profiles were associated with inflammatory markers and cytokines. The present study provides evidence for an association of IgM anti-PC antibodies with pro-atherogenic T cell subsets in SLE, with a high triglyceride/low HDL lipid profile playing a facilitating major role.

Vaccination with Prevenar® boosts the production of anti-phosphorylcholine antibodies and protects APOE knockout mice from atherosclerosis

Aim: Phosphorylcholine (PC) is an oxidation-specific epitope present on oxidized LDL and apoptotic cells, as well as the capsular polysaccharide of Streptococcus pneumoniae. PC is bound by naturally occurring IgM antibodies and low levels of anti-PC IgM are a risk factor for atherosclerosis. Active immunization of atherosclerosis-prone mice with oxidized LDL, S. pneumoniae or PC conjugated to keyhole lympet hemocyanin (PC-KLH) induces high titers of anti-PC Abs and protects from atherosclerosis. However, it is unknown if existing vaccine preparations can be exploited as preventive vaccine in atherosclerosis.

FcμR in human B cell subsets in primary selective IgM deficiency, and regulation of FcμR and production of natural IgM antibodies by IGIV

IgMFcR (FcμR) are expressed on B cell and B cell subsets. Mice deficient in secreted IgM and FcμR share properties of impaired specific antibody response and autoimmunity with patient with selective IgM deficiency (SIGMD). Intravenous immunoglobulin (IGIV) regulates immune response, including modulation of IgGFc receptors. However, there are no data on the expression of FcμR in patients with SIGMD, and the effects of IGIV on FcμR. In this study, we investigated FcμR expression in naïve marginal zone (MZ), IgM memory, and class-switched memory B cells in patients with selective IgM deficiency and healthy controls. Furthermore, we examined the direct effect of IGIV on FcμR expression and on the upregulation of FcμR by TLR2 agonist (Pam3). Finally, we examined the effect of IVIG on spontaneously produced IgM and natural IgM anti-phosphorylcholine (PC) antibodies by B cells and B1 cells. FcμR expression is significantly decreased in MZ B cells in patients with SIGMD as compared to control. IGIV, at immunomodulatory concentrations, inhibited FcμR upregulation by Pam3 in MZ B cells, and IgM-depleted IGIV inhibited spontaneous secretion of natural IgM anti-PC antibodies and not total IgM by B1 cells. These data suggest that decreased FcμR expression on MZ B cells may play a role in the pathogenesis of SIGMD, and an inhibition of TLR-2-induced upregulation of FcμR by IGIV may be one of the mechanisms of its anti-inflammatory action. IGIV-induced inhibition of natural IgM antibodies may be one of the mechanisms of IGIV-induced immunoregulation.

Embryonic stem cell-derived B-1 cells engraft in immunodeficient mice, recapitulating YS B lymphopoiesis.

Abstract It has been reported that B cells are produced from embryonic stem cells (ESCs) when co-cultured with OP9 stromal cells. However, these ESC-derived B cells have not been well characterized; it is unknown whether they belong to the B-1 or B-2 lineage and whether they are transplantable into immunodeficient mice. We previously reported that the first wave of B lymphopoiesis occurs in the extra-embryonic yolk sac (YS) at the time prior to hematopoietic stem cell (HSC) emergence and these cells belong to the B-1 cell lineage. YS-derived B progenitor cells display a AA4.1+CD19+B220dim B-1 specific progenitor phenotype, are transplantable into immunodeficient mice, and secrete natural antibodies; all key features of B-1 cells. Since differentiation of ESC into blood cells recapitulates YS hematopoiesis, we hypothesized that B progenitor cells produced from mouse ESCs in vitro belong to the B-1 cell lineage. We co-cultured ESCs with OP9 stromal cells and generated Flk1+ cells. Isolated Flk1+ cells were replated onto OP9 stromal cells, and after 9–12 days of co-culture, AA4.1+CD19+B220+ cells were detected. We transplanted these cells into sublethally irradiated immunodeficient neonates. Donor-derived B-1 cells were detected in the recipient peritoneal cavity up to 6 months after transplantation. Furthermore, ESC-derived B-1 cells produced anti-phosphorylcholine antibodies detected by Elispot assay, showing the ability of these innate B-1 cells to produce natural antibodies. Thus, we have demonstrated that ESC-derived B cells engraft in vivo as functional B -1 cells secreting natural antibodies. These B cell developmental processes recapitulate B lymphopoiesis in the YS and might be utilized for innate immune cell therapy in the future.

Aryl hydrocarbon receptor modulates the development and activity of innate-like B cells (HEM1P.226)

Abstract The Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that recognizes polyaromatic hydrocarbons. While the contributions of AhR ligands to the differentiation and functions of Th17/Treg cells are relatively well understood, little is known about AhR in B cells. Microarray and quantitative PCR analysis of B cell subsets revealed that B1 and marginal zone (MZ) B cells expressed higher levels of AhR compared to follicular (FO) B cells. We found ~ two-fold more B1 B cells, but fewer MZ B cells in AhR-/- mice compared to AhR+/+ mice. Following immunization with Streptococcus pneumonia, AhR-/- mice had significantly higher titers of anti-phosphorylcholine IgM antibodies. In contrast, after immunization with a model T cell-dependent antigen, Trinitrophenyl Keyhole Limpet Hemocyanin (TNP-KLH), AhR-/- mice had anti-TNP titers that were comparable to those in AhR+/+ mice. Further, we found significantly fewer B cells in C57BL/6 mice raised on AhR ligand free diet, and an increase in titers of IgM and IgG3 in mice following a switch to an AhR ligand free diet when compared to littermates raised and maintained on conventional diet. Taken together, these findings suggests that AhR plays a role in the development of B1 and MZ B cells and regulates T cell-independent but not T cell-dependent humoral response. Further studies using mice with a B cell specific deletion of AhR are underway to elucidate the mechanism by which AhR ligands influence humoral immunity.

IL-25 inhibits atherosclerosis development in apolipoprotein E deficient mice.

ObjectiveIL-25 has been implicated in the initiation of type 2 immunity and in the protection against autoimmune inflammatory diseases. Recent studies have identified the novel innate lymphoid type 2 cells (ILC2s) as an IL-25 target cell population. The purpose of this study was to evaluate if IL-25 has any influence on atherosclerosis development in mice.Methods and ResultsAdministration of 1 μg IL-25 per day for one week to atherosclerosis-prone apolipoprotein (apo)E deficient mice, had limited effect on the frequency of T cell populations, but resulted in a large expansion of ILC2s in the spleen. The expansion was accompanied by increased levels of anti-phosphorylcholine (PC) natural IgM antibodies in plasma and elevated levels of IL-5 in plasma and spleen. Transfer of ILC2s to apoE deficient mice elevated the natural antibody-producing B1a cell population in the spleen. Treatment of apoE/Rag-1 deficient mice with IL-25 was also associated with extensive expansion of splenic ILC2s and increased plasma IL-5, suggesting ILC2s to be the source of IL-5. Administration of IL-25 in IL-5 deficient mice resulted in an expanded ILC2 population, but did not stimulate generation of anti-PC IgM, indicating that IL-5 is not required for ILC2 expansion but for the downstream production of natural antibodies. Additionally, administration of 1 μg IL-25 per day for 4 weeks in apoE deficient mice reduced atherosclerosis in the aorta both during initiation and progression of the disease.ConclusionsThe present findings demonstrate that IL-25 has a protective role in atherosclerosis mediated by innate responses, including ILC2 expansion, increased IL-5 secretion, B1a expansion and natural anti-PC IgM generation, rather than adaptive Th2 responses.

Intrathecal Treatment with the Anti-Phosphorylcholine Monoclonal Antibody TEPC-15 Decreases Neuronal Damage in Experimental Pneumococcal Meningitis

Background: Neuronal injury in pneumococcal meningitis is a consequence of microglial activation and direct toxicity by bacterial products and systemic inflammation. Methods: The treatment effect of the TEPC-15 antibody recognizing teichoic and lipoteichoic acids was investigated in murine microglial cells and in a rabbit model of pneumococcal meningitis. Results: In vitro, the TEPC-15 antibody recognizing teichoic and lipoteichoic acids increased Streptococcus pneumoniae phagocytosis by murine microglial cells. In rabbit ceftriaxone-treated S. pneumoniae meningitis, intracisternal TEPC-15 reduced the density of apoptotic neurons in the hippocampal dentate gyrus (116 ± 70 vs. 221 ± 132/mm²; p = 0.03). Cerebrospinal fluid inflammatory parameters (protein, lactate, leukocytes, prostaglandins) were not reduced in TEPC-15-treated rabbits. Conclusion: Intracisternal treatment with the TEPC-15 antibody reduced neuronal damage probably by promoting rapid phagocytosis of bacterial products.

Carotid Atherosclerosis, Disease Measures, Oxidized Low-density Lipoproteins, and Atheroprotective Natural Antibodies for Cardiovascular Disease in Early Rheumatoid Arthritis — An Inception Cohort Study

Although an enhanced risk of cardiovascular disease (CVD) in persons with rheumatoid arthritis (RA) is well established, the mechanisms behind it remain unclear. We studied whether carotid atherosclerosis, RA disease measures, or potential cardiovascular biomarkers influenced the incidence of CVD in an RA inception cohort. RA disease measures and CVD biomarkers were assessed at 0, 3, 12, 24, and 60 months after disease onset, and carotid ultrasonography after 5 years. The study outcome was incident CVD events - acute myocardial infarction, angina pectoris, congestive heart failure, or ischemic cerebrovascular event. Survival analysis and Cox and longitudinal regressions were used for statistical analyses. A total of 105 patients, without CVD events prior to RA onset, experienced 17 CVD events, an incidence rate of 1.35 events per 100 person-years (95% CI 0.71-2.0). The rate of CVD events did not differ with regard to measures of carotid intima-media thickness, but it was higher for patients with bilateral carotid plaques than for those without (p = 0.012). Improvement in Disease Activity Score for 28 joints, visual analog scale for pain, and Stanford Health Assessment Questionnaire score over the first year, as well as usage of methotrexate (MTX), was associated, independent of age, with reduction of risk of CVD event [hazard ratios 0.68 (95% CI 0.5-0.97), 0.97 (95% CI 0.95-0.99), 0.35 (95% CI 0.15-0.82), and 0.34 (95% CI 0.12-0.91), respectively]. In longitudinal analyses, increasing oxidized low-density lipoprotein (oxLDL) and probability for low antiphosphorylcholine antibodies (anti-PC) were observed in those who experienced a subsequent CVD event. Bilateral carotid plaques were associated with poor CVD-free survival. Early reductions of inflammation, pain, and disability as well as MTX usage were associated with better CVD outcome. Elevated oxLDL and low IgM anti-PC levels may link chronic inflammation in RA to enhanced risk of CVD events.

Universal expression and dual function of the atypical chemokine receptor D6 on innate-like B cells in mice

AbstractMouse innate-like B cells are a heterogeneous collection of multifunctional cells that control infection, play housekeeping roles, contribute to adaptive immunity, and suppress inflammation. We show that, among leukocytes, chemokine internalization by the D6 receptor is a unique and universal feature of all known innate-like B-cell populations and, to our knowledge, the most effective unifying marker of these cells. Moreover, we identify novel D6active B1-cell subsets, including those we term B1d, which lack CD5 and CD11b but exhibit typical B1-cell properties, including spontaneous ex vivo production of IgM, IL-10, and anti-phosphorylcholine antibody. The unprecedented opportunity to examine D6 on primary cells has allowed us to clarify its ligand specificity and show that, consistent with a scavenging role, D6 internalizes chemokines but cannot induce Ca2+ fluxes or chemotaxis. Unexpectedly, however, D6 can also suppress the function of CXCR5, a critical chemokine receptor in innate-like B-cell biology. This is associated with a reduction in B1 cells and circulating class-switched anti-phosphorylcholine antibody in D6-deficient mice. Therefore, in the present study, we identify a unifying marker of innate-like B cells, describe novel B1-cell subsets, reveal a dual role for D6, and provide the first evidence of defects in resting D6-deficient mice.

Patients with polycystic ovary syndrome have lower levels of IgM anti-phosphorylcholine antibodies than healthy women

Introduction. IgM antibodies against phosphorylcholine (IgM anti-PC) are natural autoantibodies, possibly exerting one of the atheroprotective functions of the immune system. Increased levels of these antibodies reduce the development of atherosclerosis in mice, and low levels of IgM anti-PC have been associated with increased risk for cardiovascular disease (CVD). This study compared levels of IgM anti-PC in women with polycystic ovary syndrome (PCOS, n = 111) and healthy controls (n = 79).Method. Levels of IgM anti-PC were measured with ELISA.Results. The median level of IgM anti-PC in patients with PCOS was not significantly different compared to control subjects. However, the proportion of patients with PCOS with low levels of IgM anti-PC, defined as number of individuals below the median level, was significantly higher than among healthy controls, p < 0.05. Patients with PCOS in the oldest age quintile had significantly lower level of IgM anti-PC than control subjects of similar age (p < 0.05) and younger women with PCOS (p < 0.01).Conclusion. Our results indicate that women with PCOS more frequently display below-median levels of IgM anti-PC than controls and older women with PCOS have lower median anti-PC levels. Further studies of how this finding translates into actual CVD risk in women with PCOS are needed.

Antitreponemal Antibodies Leading to Autoantibody Production and Protection from Atherosclerosis in Kitavans from Papua New Guinea

The objective of our study was to determine the prevalence of anti-infectious agent antibodies and autoantibodies in a unique non-Westernized population from Kitava, Papua New Guinea (PNG), compared to Western populations. We matched 120 serum samples from Kitavans with 437 samples from four healthy control groups. Sera were tested for the presence of anti-infectious agent antibodies (treponema, toxoplsmosis, Epstein-Barr virus, cytomegalovirus, rubella) and autoantiobodies [anti-double-stranded (ds)DNA, anti-chromatin, anti-ribonucleoprotein (RNP), anti-SSB, anti-SSA, anti-Scl-70, anti-Smith, anti-centromer, anti-SmRNP, anti-Jo-1, and anti-ribosomal-P] using the Bio-Rad BioPlex 2200. Antitreponemal antibodies were detected in 87% of PNG sera versus 0-6% of controls (P < 0.0001). Anti-dsDNA antibodies were detected in 31% of PNG samples, which was significantly higher than in three of the control groups (<10%). The outstanding high rate of antitreponemal antibodies detected in Kitavans possibly represents prior yaws disease. A low prevalence of cardiovascular disease was previously documented in Kitavans and has been attributed, in addition to their diet, to the high prevalence of natural cardioprotective autoantibodies (the IgM-antiphosphorylcholine antibodies) in this population. Treponemal infection has been shown to induce the appearance of antiphosphorylcholine antibodies. These protective autoantibodies may cross-react with the pathogenic anti-dsDNA antibodies. Thus, it is suggested that infection with treponema is associated with the presence of protective as well as pathogenic autoantibodies.

The secretome of the filarial parasite, Brugia malayi: Proteomic profile of adult excretory–secretory products

The secretome of a parasite in its definitive host can be considered to be its genome in trans, to the extent that secreted products encoded by the parasite fulfill their function in the host milieu. The ‘extended phenotype’ of the filarial parasite, Brugia malayi, is of particular interest because of the evidence that infection results in potent down-modulation of the host immune response. We collected B. malayi ‘excretory–secretory’ (BES) proteins from adult parasites and using a combination of shotgun LC–MS/MS and 2D gel electrophoresis, identified 80 B. malayi and two host proteins in BES, of which 31 (38%) were detectable in whole worm extract (BmA). Products which were enriched in BES relative to BmA included phosphatidylethanolamine-binding protein (PEB), leucyl aminopeptidase (LAP, homologue of ES-62 from the related filaria Acanthocheilonema viteae), N-acetylglucosaminyltransferase (GlcNAcT) and galectin-1, in addition to the previously described major surface glycoprotein, glutathione peroxidase (gp29, GPX-1) and the cytokine homologue macrophage migration inhibitory factor (MIF-1). One of the most abundant released proteins was triose phosphate isomerase (TPI), yet many other glycolytic enzymes (such as aldolase and GAPDH) were found only in the somatic extract. Among the more prominent novel products identified in BES were a set of 11 small transthyretin-like proteins, and three glutamine-rich-repeat mucin-like proteins. Notably, no evidence was found of any secreted protein corresponding to the genome of the Wolbachia endosymbiont present in B. malayi. Western blotting with anti-phosphorylcholine (PC) monoclonal antibody identified that GlcNAcT, and not the ES-62 homologue, is the major PC-bearing protein in BES, while probing with human filariasis sera showed preferential reactivity to galectin-1 and to processed forms of myotactin. Overall, this analysis demonstrates selective release of a suite of newly identified proteins not previously suspected to be involved at the host–parasite interface, and provides important new perspectives on the biology of the filarial parasite.

Cross-reactivity of anti-phosphorylcholine antibodies to neuromuscular blockers in a murine model of immunization

Hypersensitivity reactions to curare-like neuromuscular blocking agents (NMBA) used in anesthesiology are more frequent in females and often occur at the first exposure to these drugs. To evaluate the antibody response to a hapten sharing the same allergenic epitope with NMBA in a murine model of immunization with Nitrophenylphosphorylcholine (NPPC) coupled with Keyhole Limpet Hemocyanin (KLH). BALB/c mice from both sexes were intraperitoneally immunized with NPPC–KLH with alum and boosted twice, on 7 and 14 days. The antibodies were tested for specificity to PC and for cross-reactivity to the haptens, NPPC and PC, as well as to the NMBAs. Mice immunized with NPPC–KLH produced anti-PC antibodies mainly of IgM, IgG1 and IgG3 isotypes, at similar levels in both sexes. Different affinities for the haptens were detectable between isotypes, with anti-PC IgG3 antibody reactivity mostly related to the choline portion of the NPPC hapten. When comparing among sexes, females developed greater IgG2 affinity to the hapten than males. Cross-reactivity to NMBAs was predominant among the anti-PC IgG3 antibodies, mainly in females achieving 75% of inhibition with 16 mM of suxamethonium, while other isotypes achieved up to 30% and was absent for IgE. The investigation of antibody isotypes regarding sensitization to choline-derived structures could contribute to understanding the differential ability of females to produce antibodies that are cross-reactive with NMBAs.

Atheroprotective natural anti-phosphorylcholine antibodies of IgM subclass are decreased in Swedish controls as compared to non-westernized individuals from New Guinea

ObjectiveTo determine the importance of IgM antibodies against phosphorylcholine (aPC), a novel protective factor for cardiovascular disease (CVD), in a population with a non-western life style as compared with a Swedish control group.Methods and resultsRisk factors for cardiovascular disease were determined in a group of 108 individuals aged 40–86 years from New Guinea and 108 age-and sex-matched individuals from a population based study in Sweden. Antibodies were tested by ELISA. aPC IgM levels were significantly higher among New Guineans than among Swedish controls (p < 0.0001). This difference remained significant among both men and women when controlled for LDL and blood pressure which were lower and smoking which was more prevalent in New Guineans as compared to Swedish controls (p < 0.0001). aPC IgM was significantly and negatively associated with age and systolic blood pressure among Swedish controls and with waist circumference among New Guineans. aPC IgM levels were significantly higher among women than men in both groups. The proportion of the saturated fatty acid (FA) myristic acid in serum cholesterol esters was negatively but polyunsaturated eicosapentaenoic acid and also lipoprotein (a) were positively associated with aPC IgM levels.ConclusionIgM-antibodies against PC, which have atheroprotective properties, are higher in a population from Kitava, New Guinea with a traditional lifestyle, than in Swedish Controls, and higher among women than men in both populations tested. Such antibodies could contribute to the low incidence of cardiovascular disease reported from Kitava and could also provide an explanation as to why women have a later onset of CVD than men.

The autoreactivity of anti-phosphorylcholine antibodies for atherosclerosis-associated neo-antigens and apoptotic cells.

Abs specific for phosphorylcholine (PC) are known to contribute to the immune defense against a variety of microbial infections. To assess for other types of binding interactions, we performed surveys of anti-PC Abs of diverse biologic origins and structural diversity and demonstrated a common autoreactivity for oxidatively modified low density lipoprotein and other oxidation-specific structures containing PC-Ags. We also found that cells undergoing apoptosis sequentially express a range of oxidation-specific neo-self PC determinants. Whereas natural Abs to PC recognized cells at early stages of apoptosis, by contrast, an IgG anti-PC Ab, representative of a T cell-dependent response, recognized PC determinants primarily associated with late stages of apoptosis. Cumulatively, these results demonstrate a fundamental paradigm in which Abs from both the innate and the T cell-dependent tiers of the B cell compartment recognize a minimal molecular motif arrayed both on microbes and as neo-self Ags linked to atherosclerosis and autoimmune disease.

Atherosclerosis, Autoimmunity, and Systemic Lupus Erythematosus

Atherosclerosis can be considered a chronic inflammatory condition of the vessel wall. Fatty streaks, the earliest morphological lesions of atherosclerosis, are caused by lipids (primarily of cholesteryl esters) accumulated within the macrophages (foam cells) and smooth muscle cells in the intimal layer. These lesions progress into atherosclerotic plaques containing extracellular matrix components, smooth muscle cells, macrophages, connective tissues, lymphocytes, and a fibrous cap over a pool of extracellular lipid. The primary pathogenic event in atherosclerosis is not clear. The “response to injury hypothesis” postulates that long-term endothelial cell injury, from a variety of mechanisms, alters endothelial permeability and induces leukocyte and platelet adhesion.1 The release of mitogenic factors from platelets and leukocytes was proposed to induce the migration and proliferation of smooth muscle cells from the media. The “lipid hypothesis” proposes that the retention and oxidation of LDL in the subendothelium play a central role in the atherosclerotic process.2,3 The uptake of oxidatively modified LDL by the macrophage via the scavenger receptor induces foam cell formation, but unmodified native LDL has no effect. Products of LDL oxidation, such as oxidized cholesterol, phospholipids, and isoprostanes have been detected in atherosclerotic plaques.4 Oxidized LDL has a number of pro-atherogenic effects, such as being chemotactic to monocytes and T cells, promoting inflammatory gene expression in vascular cells, and inducing the expression of the macrophage scavenger receptor. …