Naturally occurring auto-antibodies in homeostasis and disease

Altered Levels of Natural Autoantibodies against Heat Shock Proteins in Pregnant Women with Hashimoto's Thyroiditis

The function of natural autoantibodies (nAAbs) in maintaining immunological tolerance has been comprehensively explained; however, their function in pregnant patients dealing with autoimmune diseases has not been thoroughly investigated. As Hashimoto's thyroiditis (HT) is the predominant organ-specific autoimmune condition of women of childbearing age, this study's objective was to evaluate IgM and IgG nAAbs targeting mitochondrial citrate synthase (CS) and heat shock proteins (Hsp60 and Hsp70) in women diagnosed with HT who were pregnant (HTP). Serum samples collected from HTP and healthy pregnant (HP) women in the first and third trimesters were tested using in-house-developed enzyme-linked immunosorbent assays (ELISAs). Our findings indicate the stability of nAAbs against CS and Hsps throughout the pregnancies of both healthy women and those with HT. However, during both trimesters, HTP patients displayed elevated levels of IgM isotype nAAbs against Hsp60 and Hsp70 compared to HP women, suggesting a regulatory role of IgM nAAbs during the pregnancies of patients with HT. Nonetheless, levels of IgG isotype nAAbs against Hsps were lower solely in the third trimester among HTP patients, resulting in a higher IgM/IgG ratio, which indicates their importance in alterations of the nAAb network during pregnancy in patients with HT.

Effects of quercetin and genistein on egg quality, lipid profiles, and immunity in laying hens

BACKGROUND

After the peak laying stage, laying hens become susceptible to lipid accumulation and inflammatory reactions. The objective of this experiment was to examine the impact of quercetin and genistein on egg quality and lipid profiles in laying hens. A total of 240 Hy-Line Brown hens were randomly assigned to three dietary treatments. Each treatment had eight replicates, with ten hens in each replicate, and the hens were aged between 46 and 56 weeks. The test diets consisted of a corn-soybean meal-based basal diet, a basal diet supplemented with 300 mg kg-1 quercetin, and a basal diet supplemented with 300 mg kg-1 quercetin and 40 mg kg-1 genistein.

RESULTS

Results showed that, separately, supplemental quercetin significantly improved egg quality (eggshell strength, albumen height, and Haugh unit, P < 0.05) and reduced the deposition of abdominal fat (P < 0.05). Our findings also showed that, separately or as a combination, supplemental quercetin and genistein significantly increased eggshell thickness (P < 0.05), decreased the levels of lipids in serum (low-density lipoprotein cholesterol, total cholesterol, total triglycerides, and non-esterified fatty acids, P < 0.05) and significantly increased serum immunoglobulins A and G (P < 0.05), and promoted the expression of splenic immune-related genes (IgA and IL-4, P < 0.05).

CONCLUSION

This study confirmed that supplemental quercetin and genistein, either separately or in combination, can enhance eggshell thickness, lipid profiles, and immune function in aging hens. Moreover, both quercetin alone and quercetin + genistein exhibited similar abilities to lower lipid levels and improve immune function. © 2023 Society of Chemical Industry.

Following Natural Autoantibodies: Further Immunoserological Evidence Regarding Their Silent Plasticity and Engagement in Immune Activation

Contradictory reports are available on vaccine-associated hyperstimulation of the immune system, provoking the formation of pathological autoantibodies. Despite being interconnected within the same network, the role of the quieter, yet important non-pathological and natural autoantibodies (nAAbs) is less defined. We hypothesize that upon a prompt immunological trigger, physiological nAAbs also exhibit a moderate plasticity. We investigated their inducibility through aged and recent antigenic triggers. Anti-viral antibodies (anti-MMR n = 1739 and anti-SARS-CoV-2 IgG n = 330) and nAAbs (anti-citrate synthase IgG, IgM n = 1739) were measured by in-house and commercial ELISAs using Croatian (Osijek) anonymous samples with documented vaccination backgrounds. The results were subsequently compared for statistical evaluation. Interestingly, the IgM isotype nAAb showed a statistically significant connection with anti-MMR IgG seropositivity (p < 0.001 in all cases), while IgG isotype nAAb levels were elevated in association with anti-SARS CoV-2 specific seropositivity (p = 0.019) and in heterogeneous vaccine regimen recipients (unvaccinated controls vector/mRNA vaccines p = 0.002). Increasing evidence supports the interplay between immune activation and the dynamic expansion of nAAbs. Consequently, further questions may emerge regarding the ability of nAAbs silently shaping the effectiveness of immunization. We suggest re-evaluating the impact of nAAbs on the complex functioning of the immunological network.

A Monovalent Fab Affinity-Capture and Elution Bridging Immunoassay Overcomes Rheumatoid Factor Interference while Accurately Detecting Antidrug Antibodies

BACKGROUND

Rheumatoid factor (RF) consists of autoantibodies that bind the fragment crystallizable (Fc) region of human immunoglobulin G (IgG) and present in sera of rheumatoid arthritis (RA) patients. Immunoassays to detect antidrug antibodies (ADA) in RA patient samples may experience interference due to RF binding and crosslinking Fc regions of the capture and detection antibody reagents. To overcome this interference, a novel Fab affinity-capture and elution (ACE)-bridging immunoassay (Fab ACE-Bridge) was developed with monovalent-recombinant Fab to avoid RF interference.

METHODS

ACE and ACE-Bridge assays were developed to detect ADA against a therapeutic monoclonal antibody using samples from healthy donors, psoriasis patients, and RA patients. The performance of these assays was compared to a novel Fab ACE-Bridge assay, in which monoclonal antibody was replaced with monovalent Fab.

RESULTS

High screening signals in the ACE and ACE-Bridge assays were detected in RA patient samples but not in samples from healthy donors or psoriasis patients. The high screening signals in RA samples did not inhibit to the expected extent in the confirmatory assay, a consistent feature of false-positive screening results. Further investigation revealed RF as the interferent affecting assay performance. Modification of the ACE-Bridge assay by using monovalent Fab eliminated RF interference while allowing for sensitive and drug-tolerant detection of authentic ADA.

CONCLUSIONS

RF interfered significantly in traditional ACE and ACE-Bridge assays. Implementation of a novel monovalent Fab ACE-Bridge assay overcame RF interference. The use of monovalent Fab is recommended for immunogenicity assays when assessing ADA in RA patient samples.

Severe COVID-19 patients exhibit elevated levels of autoantibodies targeting cardiolipin and platelet glycoprotein with age: a systems biology approach

Age is a significant risk factor for the coronavirus disease 2019 (COVID-19) severity due to immunosenescence and certain age-dependent medical conditions (e.g., obesity, cardiovascular disorder, and chronic respiratory disease). However, despite the well-known influence of age on autoantibody biology in health and disease, its impact on the risk of developing severe COVID-19 remains poorly explored. Here, we performed a cross-sectional study of autoantibodies directed against 58 targets associated with autoimmune diseases in 159 individuals with different COVID-19 severity (71 mild, 61 moderate, and 27 with severe symptoms) and 73 healthy controls. We found that the natural production of autoantibodies increases with age and is exacerbated by SARS-CoV-2 infection, mostly in severe COVID-19 patients. Multiple linear regression analysis showed that severe COVID-19 patients have a significant age-associated increase of autoantibody levels against 16 targets (e.g., amyloid β peptide, β catenin, cardiolipin, claudin, enteric nerve, fibulin, insulin receptor a, and platelet glycoprotein). Principal component analysis with spectrum decomposition and hierarchical clustering analysis based on these autoantibodies indicated an age-dependent stratification of severe COVID-19 patients. Random forest analysis ranked autoantibodies targeting cardiolipin, claudin, and platelet glycoprotein as the three most crucial autoantibodies for the stratification of severe COVID-19 patients ≥50 years of age. Follow-up analysis using binomial logistic regression found that anti-cardiolipin and anti-platelet glycoprotein autoantibodies significantly increased the likelihood of developing a severe COVID-19 phenotype with aging. These findings provide key insights to explain why aging increases the chance of developing more severe COVID-19 phenotypes.

Application of nanoplasmonic biosensors based on nanoarrays in biological and chemical detection

Technological innovation, cost effectiveness, and miniaturization are key factors that determine the commercial adaptability and sustainability of sensing platforms. Nanoplasmonic biosensors based on nanocup or nanohole arrays are attractive for the development of various miniaturized devices for clinical diagnostics, health management, and environmental monitoring. In this review, we discuss the latest trends in the engineering and development of nanoplasmonic sensors as biodiagnostic tools for the highly sensitive detection of chemical and biological analytes. We focused on studies that have explored flexible nanosurface plasmon resonance systems using a sample and scalable detection approach in an effort to highlight multiplexed measurements and portable point-of-care applications.

Patients with ACPA-positive and ACPA-negative rheumatoid arthritis show different serological autoantibody repertoires and autoantibody associations with disease activity

Patients with rheumatoid arthritis (RA) can test either positive or negative for circulating anti-citrullinated protein antibodies (ACPA) and are thereby categorized as ACPA-positive (ACPA+) or ACPA-negative (ACPA-), respectively. In this study, we aimed to elucidate a broader range of serological autoantibodies that could further explain immunological differences between patients with ACPA+ RA and ACPA- RA. On serum collected from adult patients with ACPA+ RA (n = 32), ACPA- RA (n = 30), and matched healthy controls (n = 30), we used a highly multiplex autoantibody profiling assay to screen for over 1600 IgG autoantibodies that target full-length, correctly folded, native human proteins. We identified differences in serum autoantibodies between patients with ACPA+ RA and ACPA- RA compared with healthy controls. Specifically, we found 22 and 19 autoantibodies with significantly higher abundances in ACPA+ RA patients and ACPA- RA patients, respectively. Among these two sets of autoantibodies, only one autoantibody (anti-GTF2A2) was common in both comparisons; this provides further evidence of immunological differences between these two RA subgroups despite sharing similar symptoms. On the other hand, we identified 30 and 25 autoantibodies with lower abundances in ACPA+ RA and ACPA- RA, respectively, of which 8 autoantibodies were common in both comparisons; we report for the first time that the depletion of certain autoantibodies may be linked to this autoimmune disease. Functional enrichment analysis of the protein antigens targeted by these autoantibodies showed an over-representation of a range of essential biological processes, including programmed cell death, metabolism, and signal transduction. Lastly, we found that autoantibodies correlate with Clinical Disease Activity Index, but associate differently depending on patients' ACPA status. In all, we present candidate autoantibody biomarker signatures associated with ACPA status and disease activity in RA, providing a promising avenue for patient stratification and diagnostics.

Autoantibodies targeting G protein-coupled receptors: An evolving history in autoimmunity. Report of the 4th international symposium

G protein-coupled receptors (GPCR) are involved in various physiological and pathophysiological processes. Functional autoantibodies targeting GPCRs have been associated with multiple disease manifestations in this context. Here we summarize and discuss the relevant findings and concepts presented in the biennial International Meeting on autoantibodies targeting GPCRs (the 4th Symposium), held in Lübeck, Germany, 15-16 September 2022. The symposium focused on the current knowledge of these autoantibodies' role in various diseases, such as cardiovascular, renal, infectious (COVID-19), and autoimmune diseases (e.g., systemic sclerosis and systemic lupus erythematosus). Beyond their association with disease phenotypes, intense research related to the mechanistic action of these autoantibodies on immune regulation and pathogenesis has been developed, underscoring the role of autoantibodies targeting GPCRs on disease outcomes and etiopathogenesis. The observation repeatedly highlighted that autoantibodies targeting GPCRs could also be present in healthy individuals, suggesting that anti-GPCR autoantibodies play a physiologic role in modeling the course of diseases. Since numerous therapies targeting GPCRs have been developed, including small molecules and monoclonal antibodies designed for treating cancer, infections, metabolic disorders, or inflammatory conditions, anti-GPCR autoantibodies themselves can serve as therapeutic targets to reduce patients' morbidity and mortality, representing a new area for the development of novel therapeutic interventions.

Cross-sectional analysis reveals autoantibody signatures associated with COVID-19 severity

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with increased levels of autoantibodies targeting immunological proteins such as cytokines and chemokines. Reports further indicate that COVID-19 patients may develop a broad spectrum of autoimmune diseases due to reasons not fully understood. Even so, the landscape of autoantibodies induced by SARS-CoV-2 infection remains uncharted territory. To gain more insight, we carried out a comprehensive assessment of autoantibodies known to be linked to diverse autoimmune diseases observed in COVID-19 patients in a cohort of 231 individuals, of which 161 were COVID-19 patients (72 with mild, 61 moderate, and 28 with severe disease) and 70 were healthy controls. Dysregulated IgG and IgA autoantibody signatures, characterized mainly by elevated concentrations, occurred predominantly in patients with moderate or severe COVID-19 infection. Autoantibody levels often accompanied anti-SARS-CoV-2 antibody concentrations while stratifying COVID-19 severity as indicated by random forest and principal component analyses. Furthermore, while young versus elderly COVID-19 patients showed only slight differences in autoantibody levels, elderly patients with severe disease presented higher IgG autoantibody concentrations than young individuals with severe COVID-19. This work maps the intersection of COVID-19 and autoimmunity by demonstrating the dysregulation of multiple autoantibodies triggered during SARS-CoV-2 infection. Thus, this cross-sectional study suggests that SARS-CoV-2 infection induces autoantibody signatures associated with COVID-19 severity and several autoantibodies that can be used as biomarkers of COVID-19 severity, indicating autoantibodies as potential therapeutical targets for these patients.

TLR7 and IgM: Dangerous Partners in Autoimmunity

The B cell antigen receptor (BCR)-repertoire is capable of recognizing a nearly unlimited number of antigens. Inevitably, the random nature of antibody gene segment rearrangement, needed in order to provide mature B cells, will generate autoreactive specificities. Once tolerance mechanisms fail to block the activation and differentiation of autoreactive B cells, harmful autoantibodies may get secreted establishing autoimmune diseases. Besides the hallmark of autoimmunity, namely IgG autoantibodies, IgM autoantibodies are also found in many autoimmune diseases. In addition to pathogenic functions of secreted IgM the IgM-BCR expressing B cell might be the initial check-point where, in conjunction with innate receptor signals, B cell mediated autoimmunity starts it fateful course. Recently, pentameric IgM autoantibodies have been shown to contribute significantly to the pathogenesis of various autoimmune diseases, such as rheumatoid arthritis (RA), autoimmune hemolytic anemia (AIHA), pemphigus or autoimmune neuropathy. Further, recent studies suggest differences in the recognition of autoantigen by IgG and IgM autoantibodies, or propose a central role of anti-ACE2-IgM autoantibodies in severe COVID-19. However, exact mechanisms still remain to be uncovered in detail. This article focuses on summarizing recent findings regarding the importance of autoreactive IgM in establishing autoimmune diseases.

Wasteosomes (corpora amylacea) of human brain can be phagocytosed and digested by macrophages

Background

Corpora amylacea of human brain, recently renamed as wasteosomes, are granular structures that appear during aging and also accumulate in specific areas of the brain in neurodegenerative conditions. Acting as waste containers, wasteosomes are formed by polyglucosan aggregates that entrap and isolate toxic and waste substances of different origins. They are expelled from the brain to the cerebrospinal fluid (CSF), and can be phagocytosed by macrophages. In the present study, we analyze the phagocytosis of wasteosomes and the mechanisms involved in this process. Accordingly, we purified wasteosomes from post-mortem extracted human CSF and incubated them with THP-1 macrophages. Immunofluorescence staining and time-lapse recording techniques were performed to evaluate the phagocytosis. We also immunostained human hippocampal sections to study possible interactions between wasteosomes and macrophages at central nervous system interfaces.

Results

We observed that the wasteosomes obtained from post-mortem extracted CSF are opsonized by MBL and the C3b complement protein. Moreover, we observed that CD206 and CD35 receptors may be involved in the phagocytosis of these wasteosomes by THP-1 macrophages. Once phagocytosed, wasteosomes become degraded and some of the resulting fractions can be exposed on the surface of macrophages and interchanged between different macrophages. However, brain tissue studies show that, in physiological conditions, CD206 but not CD35 receptors may be involved in the phagocytosis of wasteosomes.

Conclusions

The present study indicates that macrophages have the machinery required to process and degrade wasteosomes, and that macrophages can interact in different ways with wasteosomes. In physiological conditions, the main mechanism involve CD206 receptors and M2 macrophages, which trigger the phagocytosis of wasteosomes without inducing inflammatory responses, thus avoiding tissue damage. However, altered wasteosomes like those obtained from post-mortem extracted CSF, which may exhibit waste elements, become opsonized by MBL and C3b, and so CD35 receptors constitute another possible mechanism of phagocytosis, leading in this case to inflammatory responses.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00915-2.

Rheumatoid factor IgM autoantibodies control IgG homeostasis

Rheumatoid arthritis is an autoimmune disease characterized by joint inflammation due to autoantibodies targeting multiple self-proteins. Most patients with poor prognosis show elevated titers of IgM antibodies specifically binding to IgG. Such autoreactive antibodies are referred to as rheumatoid factor (RF). However, their biological function and contribution to disease progression remains elusive. We have recently shown that autoreactive antibodies are present in healthy individuals and play an important role in regulating physiological processes. This regulatory mechanism is determined by the class and affinity of the autoreactive antibody, as low-affinity autoreactive IgM neutralizes the recognized autoantigen while high-affinity IgM protects its autoantigen from degradation. Here, we show that RFs possessing a high affinity and mono-specificity to IgG have a stabilizing effect on IgG, whereas low-affinity polyreactive RFs neutralize IgG in vivo. These results suggest that autoreactive IgM antibodies recognizing IgG play a crucial role in regulating IgG homeostasis and that a disbalance between IgM-mediated IgG degradation and stabilization might affect the onset and progression of autoimmune diseases. Consequently, restoring this balance using low-affinity anti-IgG IgM might be a promising therapeutic approach for autoimmune diseases involving autoreactive IgG.

Antibody Diversity in Cancer: Translational Implications and Beyond

Patients with cancer tend to develop antibodies to autologous proteins. This phenomenon has been observed across multiple cancer types, including bladder, lung, colon, prostate, and melanoma. These antibodies potentially arise due to induced inflammation or an increase in self-antigens. Studies focusing on antibody diversity are particularly attractive for their diagnostic value considering antibodies are present at an early diseased stage, serum samples are relatively easy to obtain, and the prevalence of antibodies is high even when the target antigen is minimally expressed. Conversely, the surveillance of serum proteins in cancer patients is relatively challenging because they often show variability in expression and are less abundant. Moreover, an antibody’s presence is also useful as it suggests the relative immunogenicity of a given antigen. For these reasons, profiling antibodies’ responses is actively considered to detect the spread of antigens following immunotherapy. The current review focuses on expanding the knowledge of antibodies and their diversity, and the impact of antibody diversity on cancer regression and progression.

Impact of Enrichment and Repeated Mixing on Resilience in Pigs

Resilience, the capacity of animals to be minimally affected by a disturbance or to rapidly bounce back to the state before the challenge, may be improved by enrichment, but negatively impacted by a high allostatic load from stressful management procedures in pigs. We investigated the combined effects of diverging environmental conditions from weaning and repeated mixing to create high allostatic load on resilience of pigs. Pigs were either exposed to barren housing conditions (B) from weaning onwards or provided with sawdust, extra toys, regular access to a “play arena” and daily positive human contact (E). Half of the pigs were exposed to repeated mixing (RM) and the other half to one mixing only at weaning (minimal mixing, MM). To assess their resilience, the response to and recovery from a lipopolysaccharide (LPS) sickness challenge and a Frustration challenge were studied. In addition, potential long-term resilience indicators, i.e. natural antibodies, hair cortisol and growth were measured. Some indications of more favorable responses to the challenges in E pigs were found, such as lower serum reactive oxygen metabolite (dROM) concentrations and a smaller area under the curve of dROM after LPS injection. In the Frustration challenge, E pigs showed less standing alert, escape behaviors and other negative behaviors, a tendency for a smaller area under the curve of salivary cortisol and a lower plasma cortisol level at 1 h after the challenge. Aggression did not decrease over mixings in RM pigs and was higher in B pigs than in E pigs. Repeated mixing did not seem to reduce resilience. Contrary to expectations, RM pigs showed a higher relative growth than MM pigs during the experiment, especially in the week of the challenges. Barren RM pigs showed a lower plasma cortisol concentration than barren MM pigs after the LPS challenge, which may suggest that those RM pigs responded less detrimentally than MM pigs. Enriched RM pigs showed a higher level of IgM antibodies binding keyhole limpet hemocyanin (KLH) than enriched MM and barren RM pigs, and RM pigs showed a sharper decline in IgG antibodies binding Bovine Serum Albumin (PC-BSA) over time than MM pigs. Hair cortisol concentrations were not affected by enrichment or mixing. To conclude, enrichment did not enhance the speed of recovery from challenges in pigs, although there were indications of reduced stress. Repeated as opposed to single mixing did not seem to aggravate the negative effects of barren housing on resilience and for some parameters even seemed to reduce the negative effects of barren housing.

Adaptive tolerance: Protection through self-recognition

The random nature of immunoglobulin gene segment rearrangement inevitably leads to the generation of self-reactive B cells. Avoidance of destructive autoimmune reactions is necessary in order to maintain physiological homeostasis. However, current central and peripheral tolerance concepts fail to explain the massive number of autoantibody-borne autoimmune diseases. Moreover, recent studies have shown that in physiological mouse models autoreactive B cells were neither clonally deleted nor kept in an anergic state, but were instead able to mount autoantibody responses. We propose that activation of autoreactive B cells is induced by polyvalent autoantigen complexes that can occur under physiological conditions. Repeated encounter of autoantigen complexes leads to the production of affinity-matured autoreactive IgM that protects its respective self-targets from degradation. We refer to this novel mechanism as adaptive tolerance. This article discusses the discovery of adaptive tolerance and the unexpected role of high affinity IgM autoantibodies.

From corpora amylacea to wasteosomes: History and perspectives

Corpora amylacea (CA) have been described in several human organs and have been associated with ageing and several pathological conditions. Although they were first discovered two centuries ago, their function and significance have not yet been identified. Here, we provide a chronological summary of the findings on CA in various organs and identify their similarities. After collecting and integrating these findings, we propose to consider CA as waste containers created by specific cells, which sequester waste products and foreign products, and assemble them within a glycan structure. The containers are then secreted into the external medium or interstitial spaces, in this latter case subsequently being phagocytosed by macrophages. This proposal explains, among others, why CA are so varied in content, why only some of them contain fibrillary amyloid proteins, why all of them contain glycan structures, why some of them contain neo-epitopes and are phagocytosed, and why they can be intracellular or extracellular structures. Lastly, in order to avoid the ambiguity of the term amyloid (which can indicate starch-like structures but also insoluble fibrillary proteins), we propose renaming CA as "wasteosomes", emphasising the waste products they entrap rather than their misleading amyloid properties.

Cross-reactive, natural IgG recognizing L. major promote parasite internalization by dendritic cells and promote protective immunity

In cutaneous leishmaniasis, infection of dendritic cells (DC) is essential for generation of T cell-dependent protective immunity. DC acquires Leishmania major through Fc receptor (FcR)-mediated uptake of complexes comprising antibodies bound to parasites. We now assessed the development of the initial B cell and DC response to the parasite itself and if natural IgG play a role. L. major parasites display large numbers of phospholipids on their surface. Parasites were opsonized with normal mouse serum (NMS), or serum containing anti-phospholipid IgG (PL). We found that L. major bound to PL which significantly enhanced parasite phagocytosis by DC as compared to NMS. Similar results were obtained with cross-reactive human PL antibodies using myeloid primary human DC. In addition, mice infected with PL-opsonized parasites showed significantly improved disease outcome compared to mice infected with NMS-opsonized parasites. Finally, IgMi mice, which produce membrane-bound IgM only and no secreted antibodies, displayed increased susceptibility to infection as compared to wild types. Interestingly, once NMS was administered to IgMi mice, their phenotype was normalized to that of wild types. Upon incubation with IgG-opsonized parasite (IgG derived from infected mice or using PL antibodies), also the IgMi mice were able to show superior immunity. Our findings suggest that "natural" cross-reactive antibodies (e.g., anti-PL Ab) in NMS bind to pathogens to facilitate phagocytosis, which leads to induction of protective immunity via preferential DC infection. Prior L. major-specific B cell-priming does not seem to be absolutely required to facilitate clearance of this important human pathogen in vivo. KEY MESSAGES: We found that anti-phospholipid (anti-PL) antibodies enhance phagocytosis of L. major by DCs. We also found that normal mouse sera have natural antibodies that can imitate PL specific antibodies. Using different genetically modified mice, we found that these antibodies can be IgG, not only IgM.

Tisagenlecleucel Immunogenicity in Relapsed/Refractory Acute Lymphoblastic Leukemia and Diffuse Large B-Cell Lymphoma

Pre- and posttreatment anti-mCAR19 antibodies did not alter tisagenlecleucel cellular kinetics, efficacy, or safety in r/r B-ALL or r/r DLBCL.

T-cell responses to mCAR19 peptides did not influence patient outcomes or cellular expansion in r/r B-ALL or r/r DLBCL.

Tisagenlecleucel is indicated for pediatric and young adult patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL) and adult patients with r/r diffuse large B-cell lymphoma (DLBCL). The tisagenlecleucel chimeric antigen receptor (CAR) contains a murine single-chain variable fragment domain; we examined the effects of humoral and cellular immune responses to tisagenlecleucel on clinical outcomes using 2 validated assays. Data were pooled from the ELIANA (registered at www.clinicaltrials.gov as #NCT02435849) and ENSIGN (#NCT02228096) trials in r/r B-ALL (N = 143) and the JULIET trial (#NCT02445248) in r/r DLBCL (N = 115). Humoral responses were determined by flow cytometric measurement of anti-murine CAR19 (mCAR19) antibodies in serum. Cellular responses were determined using T-cell production of interferon-γ in response to 2 different pools of mCAR19 peptides. Pretreatment anti-mCAR19 antibodies were detected in 81% of patients with r/r B-ALL and 94% of patients with r/r DLBCL. Posttreatment anti-mCAR19 antibodies were higher than patient-specific baseline in 42% of r/r B-ALL and 9% of r/r DLBCL patients. Pretreatment and posttreatment anti-mCAR19 antibodies did not affect tisagenlecleucel cellular kinetics, including maximum concentration and persistence (r² < 0.05), clinical response (day-28 response, duration of response, and event-free survival), and safety. T-cell responses were consistent over time, with net responses <1% at baseline and posttreatment time points in a majority of patients and no effect on transgene expansion or persistence or outcomes. Presence of baseline and/or posttreatment anti-mCAR19 antibodies or T-cell responses did not alter the activity of tisagenlecleucel in patients with r/r B-ALL or r/r DLBCL.

Corpora Amylacea in the Human Brain Exhibit Neoepitopes of a Carbohydrate Nature

Corpora amylacea (CA) in the human brain are polyglucosan bodies that accumulate residual substances originated from aging and both neurodegenerative and infectious processes. These structures, which act as waste containers, are released from the brain to the cerebrospinal fluid, reach the cervical lymph nodes via the meningeal lymphatic system and may be phagocytosed by macrophages. Recent studies indicate that CA present certain neoepitopes (NEs) that can be recognized by natural antibodies of the IgM class, and although evidence of different kinds suggests that these NEs may be formed by carbohydrate structures, their precise nature is unknown. Here, we adapted standard techniques to examine this question. We observed that the preadsorption of IgMs with specific carbohydrates has inhibitory effects on the interaction between IgMs and CA, and found that the digestion of CA proteins had no effect on this interaction. These findings point to the carbohydrate nature of the NEs located in CA. Moreover, the present study indicates that, in vitro, the binding between certain natural IgMs and certain epitopes may be disrupted by certain monosaccharides. We wonder, therefore, whether these inhibitions may also occur in vivo. Further studies should now be carried out to assess the possible in vivo effect of glycemia on the reactivity of natural IgMs and, by extension, on natural immunity.

Autoimmune Disorders of the Nervous System: Pathophysiology, Clinical Features, and Therapy

Remarkable discoveries over the last two decades have elucidated the autoimmune basis of several, previously poorly understood, neurological disorders. Autoimmune disorders of the nervous system may affect any part of the nervous system, including the brain and spinal cord (central nervous system, CNS) and also the peripheral nerves, neuromuscular junction and skeletal muscle (peripheral nervous system, PNS). This comprehensive overview of this rapidly evolving field presents the factors which may trigger breakdown of self-tolerance and development of autoimmune disease in some individuals. Then the pathophysiological basis and clinical features of autoimmune diseases of the nervous system are outlined, with an emphasis on the features which are important to recognize for accurate clinical diagnosis. Finally the latest therapies for autoimmune CNS and PNS disorders and their mechanisms of action and the most promising research avenues for targeted immunotherapy are discussed.

Effects of early nutrition and sanitary conditions on antibody levels in early and later life of broiler chickens

Immune maturation of broiler chickens may be affected by management, such as early life feeding strategy (early versus delayed nutrition) or by low or high sanitary conditions (LSC versus HSC). We compared systemic maternal (MAb), natural (NAb), natural auto- (NAAb), and antigen specific antibody (SpAb) levels (IgM, IgY) between broilers (n = 48 per treatment) that received early (EN) or delayed nutrition for 72 h (DN) housed in either low (LSC) or high sanitary conditions (HSC) between 7 and 35 d of age. We found minimal interactions between feeding strategy and sanitary conditions. At 7 d of age, broilers receiving EN compared with DN, had elevated levels of IgM binding keyhole limpet hemocyanin (KLH), phosphoryl-conjugated ovalbumin (PC-OVA), and muramyl dipeptide (MDP), whereas effects of feeding strategy diminished at later ages. In LSC compared with HSC broilers, levels of NAb agglutinating RRBC and sheep red blood cells (SRBC) were already elevated from 14 d of age onwards. At 33 d of age, antibody levels (NAb, NAAb, anti-LPS, anti-MDP) were all elevated in LSC, compared with HSC broilers, for both IgM and IgY, but not IgM against KLH. Western blotting revealed different binding patterns of NAAb against chicken liver homogenate, which may indicate that the NAAb repertoire is affected by antigenic pressure. Our data suggest that antibody levels are affected for an important part by environmental conditions (feeding strategy and sanitary conditions), but minimally by their interaction. However, it remains to be further studied whether the enhanced levels of antibodies as initiated by EN and LSC contribute to enhanced resistance to infectious diseases.

Effect of red seaweed sulfated galactans on initial steps of complement activation in vitro

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Red algal galactans can participate in cell surface biology involving complement system.

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Polysaccharides inhibit C3 binding to LPS with direct dependence on degree of sulfation.

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Degree of sulfation mattered in carrageenans capacity to reduce C4 binding to mannan.

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C4 binding to antibodies was activated in the presence of carrageenans.

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No relevant structural characteristics were observed in ameliorating C5 cleavage by plasmin.

The research described here presents data on the effect of galactans of red algae, carrageenans (λ/μ/ν-, κ-, κ/β-, and ι/κ-types), and agar on complement system activation in normal human serum. The experiments were based on well surfaces coated with triggering agents for binding initiating complement components —C3 and C4. The sulfated galactans inhibited C3 binding to lipopolysaccharide with direct dependence on the sulfation degree of polysaccharides. Sulfation degree was also important in carrageenans’ capacity to reduce C4 binding to mannan. However, C4 binding to antibodies was considerably activated by carrageenans, especially with 3,6-anhydrogalactose. The gelling carrageenans were able to block antigen binding centers of total serum IgM and with more intensity than non-gelling. No structural characteristics mattered in ameliorating C5 cleavage by plasmin in extrinsic protease complement activation, but λ/μ/ν- and κ/β-carrageenans almost completely inhibited C5 cleavage. Thus, galactans participated in cell surface biology by imitating surface glycans in inhibition of C3 binding and mannose binding lectin, but as to the tthe heclassical pathway these substances stimulated complement, probably due to their structure based on carrabiose.

Current Understanding of Natural Antibodies and Exploring the Possibilities of Modulation Using Veterinary Models. A Review

Natural antibodies (NAb) are defined as germline encoded immunoglobulins found in individuals without (known) prior antigenic experience. NAb bind exogenous (e.g., bacterial) and self-components and have been found in every vertebrate species tested. NAb likely act as a first-line immune defense against infections. A large part of NAb, so called natural autoantibodies (NAAb) bind to and clear (self) neo-epitopes, apoptotic, and necrotic cells. Such self-binding antibodies cannot, however, be considered as pathogenic autoantibodies in the classical sense. IgM and IgG NAb and NAAb and their implications in health and disease are relatively well-described in humans and mice. NAb are present in veterinary (and wildlife) species, but their relation with diseases and disorders in veterinary species are much less known. Also, there is little known of IgA NAb. IgA is the most abundant immunoglobulin with essential pro-inflammatory and homeostatic properties urging for more research on the importance of IgA NAb. Since NAb in humans were indicated to fulfill important functions in health and disease, their role in health of veterinary species should be investigated more often. Furthermore, it is unknown whether levels of NAb-isotypes and/or idiotypes can and should be modulated. Veterinary species as models of choice fill in a niche between mice and (non-human) primates, and the study of NAb in veterinary species may provide valuable new insights that will likely improve health management. Below, examples of the involvement of NAb in several diseases in mostly humans are shown. Possibilities of intravenous immunoglobulin administration, targeted immunotherapy, immunization, diet, and genetic modulation are discussed, all of which could be well-studied using animal models. Arguments are given why veterinary immunology should obtain inspiration from human studies and why human immunology would benefit from veterinary models. Within the One Health concept, findings from veterinary (and wildlife) studies can be related to human studies and vice versa so that both fields will mutually benefit. This will lead to a better understanding of NAb: their origin, activation mechanisms, and their implications in health and disease, and will lead to novel health management strategies for both human and veterinary species.

Harnessing the Therapeutic Potential of 'Rogue' Antibodies

Therapeutic antibodies have revolutionized modern medicine. At present, antibodies are successfully used for treatment of diverse human diseases, ranging from cancer to viral infections. All clinically approved antibodies rely on highly specific recognition of their target antigen. Antigen-binding promiscuity, binding to autoantigens, and propensity for self-binding (homophilic interaction) are highly undesirable characteristics of antibody drug candidates. Nevertheless, the immune system of all healthy individuals constantly produces and uses large quantities of antibodies that can be classified as inappropriate for development as drugs. Here, I provide arguments that antibodies with 'aberrant' properties have therapeutic potential. They could be useful in certain complex pathological conditions, thus enriching our armamentarium for treatment of human diseases.

Early-life microbiota transplantation affects behavioural responses, serotonin and immune characteristics in chicken lines divergently selected on feather pecking

Gut microbiota influences host behaviour and physiology, such as anxiety, stress, serotonergic and immune systems. These behavioural and physiological characteristics are related to feather pecking (FP), a damaging behaviour in chickens that reduces animal welfare and productivity. Moreover, high FP (HFP) and low FP (LFP) lines differed in microbiota composition. However, it is unknown whether microbiota can influence the development of FP. For the first time, we identified the effects of microbiota transplantation on FP, and behavioural and physiological characteristics related to FP. HFP and LFP chicks received sterile saline (control), HFP or LFP microbiota transplantation during the first two weeks post-hatch. Microbiota transplantation influenced behavioural responses of the HFP line during treatment and of the LFP line after treatment. In both lines, homologous microbiota transplantation (i.e., receiving microbiota from their line) resulted in more active behavioural responses. Furthermore, microbiota transplantation influenced immune characteristics (natural antibodies) in both lines and peripheral serotonin in the LFP line. However, limited effects on microbiota composition, stress response (corticosterone) and FP were noted. Thus, early-life microbiota transplantation had immediate and long-term effects on behavioural responses and long-term effects on immune characteristics and peripheral serotonin; however, the effects were dependent on host genotype. Since early-life microbiota transplantation influenced behavioural and physiological characteristics that are related to FP, it could thus influence the development of FP later in life.

Transfer of natural auto-antibodies via egg yolk in chickens divergently selected for natural antibodies binding keyhole limpet hemocyanin

Barcodes of natural auto-antibody (NAAb) profiles based on staining intensity of isotypes binding numbers of self-(tissue) antigen fragments were suggested as parameters for immune diversity, and related to genetic background and health status in man, rodents and poultry. Here, hens, eggs and hatchlings from chicken lines divergently selected and bred for high (H line) or low (L line) total natural antibodies (NAb) levels in plasma binding keyhole limpet hemocyanin (KLH) at 16 weeks of age were tested for their NAAb repertoire binding chicken liver homogenate (CLH) fragments using quantitative Western immunoblotting. The aims of this study were 1. to detect line differences between the H and L line adult hens, eggs and hatchlings for the IgM and IgG isotypes binding CLH fragments, 2. study the presence of NAAb of both isotypes in yolk and albumen, as well as in hatchlings to detect a maternal NAAb transfer route via the egg to the hatchling, and 3. study whether new self-antigen binding isotypes and idiotypes are present in the hatchling. NAAb binding CLH fragments were found in plasma of adult hens (both IgM and IgG), in yolk (IgG only), and hatchlings (mostly IgG, but low levels of IgM). Auto-profiles of IgM showed homogeneity, while IgG profiles were heterogenic between individual hens and individual hatchlings. Significant higher levels as indicated by staining intensity and number of stained CLH fragments were found in plasma of hens genetically selected for high levels of NAb binding KLH. Lines could be clustered based on their auto-profiles indicating that profiles of self-binding IgM and IgG antibodies are genetically based. Visual comparison, clustering and correlation of hens and their hatchlings showed similarities for the IgG, but not the IgM isotype, indicating maternal transfer of IgG NAAb via the yolk. The IgM profile in the hatchlings on the other hand might represent neonatal self-binding antibody formation. As a consequence, hatchlings initially depend for self-binding antibodies on maternal IgG provision during early life.

Effects of IVIg treatment on autoantibody testing in neurological patients: marked reduction in sensitivity but reliable specificity

BACKGROUND

Therapy of autoimmune diseases of the central and peripheral nervous system with intravenous IgG immunoglobulin (IVIg) is well established. Since IVIg is produced from pooled human plasma, autoantibodies can be found in IVIg products and, accordingly, in patient sera after transfusion. The de novo evidence or disappearance of anti-neural autoantibodies after IVIg treatment has so far not been systematically examined.

METHODS

We screened 50 neurological patients before and after IVIg treatment for classical onconeural and the most common neurological surface autoantibodies as well as for ganglioside autoantibodies and 23 different antinuclear autoantibodies using immunoblot or cell-based indirect immunofluorescence assays. Furthermore, we screened 31 neurological patients with previously known seropositivity for disappearance of the corresponding antibody after treatment.

RESULTS

After IVIg treatment, 90% of all sera were de novo positive for antinuclear antibodies, especially for Ro-52. In contrast, 94% of all sera did not show any de novo-positive anti-neural antibodies. In the remaining three cases, titers were very low. Importantly, 12.9% of all tested sera of patients with known antibody positivity turned false negative after IVIg treatment and titers were falsely low in 37% of the remaining sera.

CONCLUSIONS

Here, we present for the first time results of a broad screening for clinically relevant autoantibodies before and after IVIg treatment in neurological patients. We identified a high specificity but reduced sensitivity for anti-neural antibody testing after IVIg transfusion. In contrast, antinuclear antibody testing is not reliable after IVIg treatment. These results are of high practical importance for diagnostic of neuroimmunological diseases.

Autoantibodies as Diagnostic Markers and Mediator of Joint Inflammation in Arthritis

Rheumatoid arthritis is a systemic, polygenic, and multifactorial syndrome characterized by erosive polyarthritis, damage to joint architecture, and presence of autoantibodies against several self-structures in the serum and synovial fluid. These autoantibodies (anticitrullinated protein/peptide antibodies (ACPAs), rheumatoid factors (RF), anticollagen type II antibodies, antiglucose-6 phosphate isomerase antibodies, anticarbamylated protein antibodies, and antiacetylated protein antibodies) have different characteristics, diagnostic/prognostic value, and pathological significance in RA patients. Some of these antibodies are present in the patients' serum several years before the onset of clinical disease. Various genetic and environmental factors are associated with autoantibody production against different autoantigenic targets. Both the activating and inhibitory FcγRs and the activation of different complement cascades contribute to the downstream effector functions in the antibody-mediated disease pathology. Interplay between several molecules (cytokines, chemokines, proteases, and inflammatory mediators) culminates in causing damage to the articular cartilage and bones. In addition, autoantibodies are proven to be useful disease markers for RA, and different diagnostic tools are being developed for early diagnosis of the clinical disease. Recently, a direct link was proposed between the presence of autoantibodies and bone erosion as well as in the induction of pain. In this review, the diagnostic value of autoantibodies, their synthesis and function as a mediator of joint inflammation, and the significance of IgG-Fc glycosylation are discussed.

Chicken lines divergently selected on feather pecking differ in immune characteristics

It is crucial to identify whether relations between immune characteristics and damaging behaviors in production animals exist, as these behaviors reduce animal welfare and productivity. Feather pecking (FP) is a damaging behavior in chickens, which involves hens pecking and pulling at feathers of conspecifics. To further identify relationships between the immune system and FP we characterized high FP (HFP) and low FP (LFP) selection lines with regard to nitric oxide (NO) production by monocytes, specific antibody (SpAb) titers, natural (auto)antibody (N(A)Ab) titers and immune cell subsets. NO production by monocytes was measured as indicator for innate pro-inflammatory immune functioning, SpAb titers were measured as part of the adaptive immune system and N(A)Ab titers were measured as they play an essential role in both innate and adaptive immunity. Immune cell subsets were measured to identify whether differences in immune characteristics were reflected by differences in the relative abundance of immune cell subsets. Divergent selection on FP affected NO production by monocytes, SpAb and N(A)Ab titers, but did not affect immune cell subsets. The HFP line showed higher NO production by monocytes and higher IgG N(A)Ab titers compared to the LFP line. Furthermore the HFP line tended to have lower IgM NAAb titers, but higher IgM and IgG SpAb titers compared to the LFP line. Thus, divergent selection on FP affects the innate and adaptive immune system, where the HFP line seems to have a more responsive immune system compared to the LFP line. Although causation cannot be established in the present study, it is clear that relationships between the immune system and FP exist. Therefore, it is important to take these relationships into account when selecting on behavioral or immunological traits.

Novel Molecular Leads for the Prevention of Damage and the Promotion of Repair in Neuroimmunological Disease

Neuroinflammation is a prominent pathological feature of all neuroimmunological diseases, including, but not limited to, multiple sclerosis (MS), myasthenia gravis, neuromyelitis optica, and Guillain–Barré syndrome. All currently-approved therapies for the treatment of these diseases focus on controlling or modulating the immune (innate and adaptive) responses to limit demyelination and neuronal damage. The primary purpose of this review is to detail the pre-clinical data and proposed mechanism of action of novel drugs currently in clinical trial, with a focus on novel compounds that promote repair and regeneration in the central nervous system (CNS). As the most recent advances have been made in the field of MS research, this review will focus primarily on this disease and its animal models. However, these compounds are likely to be effective for a range of indications with a neuroinflammatory component. Traditionally, MS was thought to proceed through two distinct phases. The first, predominantly inflammatory stage, is characterized by acute episodes of clinical relapse, followed by periods of partial or total recovery with an apparent absence of overall disease progression. In the vast majority of patients, this relapsing-remitting disease subsequently progresses into a second more chronic, neurodegenerative phase, which is characterized by oligodendrocyte damage and axonal destruction leading to brain atrophy and an accumulation of disability. Recent work has shown that rather than occurring independently, both the inflammatory and degenerative phases may run concurrently. This, combined with evidence that early therapeutic intervention slows accumulation of disability and delays progression, highlights the need for novel therapeutic approaches that promote repair and regeneration early in the disease trajectory. Such compounds may be used as monotherapies or in conjunction with classical anti-inflammatory therapies. This review will highlight novel therapies currently in clinical trial, and likely to appear in clinical practice in the near future, focusing on compounds that target the immune system and/or enhance endogenous repair mechanisms in the CNS.

High incidence of anti-cytokine autoantibodies in dogs with immune diseases suggests important immuno-regulatory functions

Autoantibodies against cytokines have been associated with immunodeficiency, susceptibility to infectious diseases, autoimmunity and inflammation in humans, but have not yet been investigated in the Veterinary field so far. The aim of the current study was to determine the presence of anti-cytokine autoantibodies in canines suffering from various conditions including recurrent infections, autoimmune diseases and cancer in comparison to healthy controls. This is the first report of the presence of autoantibodies against cytokines in dogs. A total of 101 serum samples (51 patients and 50 clinically healthy dogs) from the state of Mexico and surroundings were analysed using a multiplex bead-based flow cytometry assay. Results show significant levels of various anti-cytokine autoantibodies in diseased dogs but not in healthy controls. In addition we show distinct associations of various disease types to the specificity of anti-cytokine autoantibodies and to response complexities. Apart from the direct functional/causal implication of anti-cytokine auto-antibodies on disease processes, this findings point to the possibility to use anti-cytokine response patterns as diagnostic tools.

Maternal Transfer of Natural (Auto-) Antibodies in Chickens

The presence and relative levels (titers) of IgM and IgG natural antibodies (NAb) binding keyhole limpet hemocyanin (KLH), and natural (auto-) antibodies (N(A)Ab) binding salmon double-stranded DNA (dsDNA), (oxidated-) phosphatidyl (phosphoryl) choline-conjugated bovine serum albumin (PC-BSA), PC-conjugated ovalbumin (PC-OVA), and OVA, respectively, were studied in adult hen plasma, egg yolk, egg albumen, plasma of their hatchlings, and in 8-day-old chick plasma. Birds and eggs were from 2 lines divergently selected for high or low NAb levels binding KLH. This study aimed to determine 1) correlated phenotypic responses of selection for NAb to KLH, 2) transfer of maternal NAb and N(A)Ab via egg compartments, 3) levels of likely maternal NAb and N(A)Ab in hatchlings and 8-day-old chicks, and 4) whether a composite trait: IgM anti-PC-BSA/IgG anti-dsDNA ratio in the compartments could be used as a parameter for health or immune status. NAb and N(A)Ab to all tested antigens were found in adult hens, but low or no levels were found for IgM in yolk and IgG in albumen. Depending on the antigen, NAb and N(A)Ab were found in hatchlings and day 8 birds. Divergent selection and breeding based on NAb binding KLH affected antibody titers of almost all antigens in almost all compartments, in a similar way. Maternal transfer of NAb and N(A)Ab from the adult hen to offspring was via specific routes for specific antigens and isotypes, especially for IgG as suggested by cluster analyses and significant correlations. There was little indication of production of new NAb and N(A)Ab to the studied antigens in either the egg compartments or the hatchlings. A composite trait of IgM PC-BSA/IgG dsDNA ratio was as yet not indicative for immune status, as no significant differences were found between the lines for all compartments. In conclusion, hens provide neonatal chickens with natural (self-) binding IgG antibodies that have been proposed to perform homeostatic functions during the period in which neonates do not produce these antibodies themselves.

Investigation of pre-existing reactivity to biotherapeutics can uncover potential immunogenic epitopes and predict immunogenicity risk

Despite recent advances in the development of tools to predict immunogenicity risk of biotherapeutic molecules, the ability of a protein to elicit the formation of anti-drug antibodies (ADA) remains one of the most common causes for termination of clinical development programs. In this study, we use ADA assays to detect and measure pre-existing reactivity or the ability of a molecule to produce an ADA-like response in serum from treatment-naïve, healthy donors. We report herein that the magnitude of pre-existing reactivity evaluated pre-clinically and expressed as the 90th percentile of Tier 2 inhibition correlates with the subsequent rate of ADA emergence in the clinic. Furthermore, a multi-domain biotherapeutic (IgG-scFv bispecific antibody) showed the highest pre-existing reactivity and incidence of treatment-emergent ADA (TE-ADA) (57% and 93%, respectively). Using the components of the multidomain molecule in the Tier 2 step of the ADA assay, we were able to identify the scFv as the target of the serum pre-existing reactivity. Most importantly, the domain specificity of pre-existing ADA was the same as that of the TE-ADA from patients treated with the molecule. Based on these data, we propose the evaluation of the magnitude and of the domain specificity of pre-existing reactivity as a powerful tool to understand the immunogenic potential of novel biotherapeutics.

Immune Dysfunction and Albumin-Related Immunity in Liver Cirrhosis

Liver cirrhosis yearly causes 1.2 million deaths worldwide, ranking as the 10th leading cause of death in the most developed countries. High susceptibility to infections along with a significant risk for infection-related mortality justifies the description of liver cirrhosis as the world's most common immunodeficiency syndrome. Liver cirrhosis is an end-stage organic disease hallmarked by a multifaceted immune dysfunction due to deterioration of antimicrobial recognition and elimination mechanisms in macrophages along with an impaired antigen presentation ability in circulating monocytes. Bacterial translocation supports—and is supported by—uncontrolled activation of immune cell responses and/or loss of toll-like receptor (TLR) tolerance, which can turn exaggerated inflammatory responses to systemic inflammation. Lipopolysaccharide (LPS) or endotoxin boosts systemic inflammatory activity through activation of TLR-2- and TLR-4-dependent pathways and facilitate a massive production of cytokines. This, in turn, results into elevated secretion of reactive oxygen species (ROS), which further enhances intestinal hyperpermeability and thus sustains a vicious circle of events widely known as “leaky gut.” Albumin can be of particular benefit in cirrhotic patients with spontaneous bacterial peritonitis and/or hepatorenal syndrome type of acute kidney injury (HRS-AKI) due to anti-inflammatory and antioxidative stress as well as volume-expanding properties and endothelial-stabilizing attributes. However, presence of autoantibodies against albumin in patients with liver cirrhosis has been described. Although previous research suggested that these antibodies should be regarded as naturally occurring antibodies (NOA), the origin of the antialbumin immune response is obscure. High occurrence of NAO/albumin complexes in patients with liver disease might reflect a limited clearance capacity due to bypassing portal circulation. Moreover, high burden of oxidized albumin is associated with less favorable outcome in patients with liver cirrhosis. To date, there is no data available as to whether oxidized forms of albumin result in neoepitopes recognized by the immune system. Nevertheless, it is reasonable to hypothesize that these alterations may have the potential to induce antialbumin immune responses and thus favor systemic inflammation.

Stress response, peripheral serotonin and natural antibodies in feather pecking genotypes and phenotypes and their relation with coping style

Feather pecking (FP), a serious welfare and economic issue in the egg production industry, has been related to coping style. Proactive and reactive coping styles differ in, among others, the stress response, serotonergic activity and immune activity. Yet, it is unknown whether genetic lines divergently selected on FP (i.e. FP genotypes) or individuals differing in FP (i.e. FP phenotypes) can be categorized into coping styles. Therefore, we determined peripheral serotonin (5-HT) levels, natural antibody (NAb) titers, behavioral and corticosterone (CORT) responses to manual restraint (MR) in FP genotypes (high FP (HFP), low FP (LFP) and unselected control (CON) line) and FP phenotypes (feather pecker, feather pecker-victim, victim and neutral). We further examined the consistency of and relationships between behavioral and physiological measures. FP genotypes differed in behavioral responses to MR, 5-HT levels and NAb titers, but not in CORT levels after MR. HFP birds had less active responses at adolescent age, but more active responses at adult age compared to LFP and CON birds. The CON line had higher 5-HT levels at adolescent age, while the HFP line had lower 5-HT levels than the other lines at adult age. Overall, the HFP line had lower IgM NAb titers, while the LFP line had lower IgG NAb titers compared to the other lines. FP phenotypes differed in behavioral responses to MR and 5-HT levels, but not in CORT levels after MR or NAb titers. Within the HFP line, feather peckers tended to have less active responses compared to neutrals at adolescent age, while victims had more active responses compared to the other phenotypes at adult age. Feather peckers had higher 5-HT levels than neutrals at adult age. Behavioral and CORT responses to MR were not consistent over time, suggesting that responses to MR might not reflect coping style in this study. Furthermore, proactive behavioral responses were correlated with reactive physiological measures and vice versa. Thus, it was not possible to categorize FP genotypes or FP phenotypes into specific coping styles.

Anti-phosphorylcholine IgM, an Anti-inflammatory Mediator, Predicts Peripheral Vein Graft Failure: A Prospective Observational Study

OBJECTIVES

One third of infrainguinal vein bypasses may fail within the first 1.5 years. Pro- and anti-inflammatory mechanisms are thought to be involved in these graft stenoses and occlusions. In previous studies, low levels of anti-phosphorylcholine IgM (anti-PC IgM, an innate anti-inflammatory IgM) have been associated with increased cardiovascular events. In this study, the peri-operative dynamics of anti-PC IgM levels were established during leg bypass surgery, and associations assessed between anti-PC IgM levels and primary graft patency.

DESIGN AND METHODS

This was a prospective, observational cohort study of infrainguinal autogenous vein bypass for peripheral arterial occlusive disease involving four university affiliated hospitals. Plasma cytokine and anti-PC IgM levels were measured pre- and post-operatively. The outcome of interest was loss of primary graft patency because of occlusion or intervention for graft stenosis.

RESULTS

One hundred and forty-two consecutive patients were enrolled: mean age 66 (46-91); 91% white race and male; 72.5% critical limb ischaemia (Fontaine III or IV). Median pre-operative anti-PC IgM levels were 49 units/mL (IQR 32.3-107.7, mean 89.8 + 101 sd). During follow up of an average of 1.8 years (1 month-7.4 years), 50 (35.2%) grafts lost primary patency. Pre-operative levels of interleukin 6 or C-reactive protein did not predict graft failure. Patients with pre-operative anti-PC IgM values in the lowest quartile had a twofold increased risk of graft failure (multivariable Cox proportional hazard, p = .03, HR 2.11, 95% CI 1.09-4.07), even after accounting for the other significant factors of conduit diameter, distal anastomosis, smoking, and the severity of leg ischaemia.

CONCLUSIONS

Low levels of anti-PC IgM are associated with vein bypass graft failure. This biological mediator may be a useful marker to identify patients at higher risk, and offers the potential for novel, directed therapies for vascular inflammation and its consequences.

Changes in concentrations of tau-reactive antibodies are dependent on sex in Alzheimer's disease patients

The presence of pre-existing natural antibodies against Alzheimer's disease (AD) pathological proteins might interfere with immune responses to therapeutic vaccination with these proteins. We aimed to compare levels of antibodies in CSF and serum: We observed higher reactivity of natural tau-reactive antibodies towards phosphorylated bovine tau protein than to human recombinant (non-phosphorylated) tau protein. Males with MCI-AD had higher amounts of these antibodies than corresponding controls. Concentrations of antibodies were lower in females with the MCI-AD than in control females. These findings may have implications for tau vaccination trials.

Linking autoimmunity to the origin of the adaptive immune system

In jawed vertebrates, the adaptive immune system (AIS) cooperates with the innate immune system (IIS) to protect hosts from infections. Although targeting non-self-components, the AIS also generates self-reactive antibodies which, when inadequately counter-selected, can give rise to autoimmune diseases (ADs). ADs are on the rise in western countries. Why haven’t ADs been eliminated during the evolution of a ∼500 million-year old system? And why have they become more frequent in recent decades? Self-recognition is an attribute of the phylogenetically more ancient IIS and empirical data compellingly show that some self-reactive antibodies, which are classifiable as elements of the IIS rather then the AIS, may protect from (rather than cause) ADs. Here, we propose that the IIS’s self-recognition system originally fathered the AIS and, as a consequence of this relationship, its activity is dampened in hygienic environments. Rather than a mere breakdown or failure of the mechanisms of self-tolerance, ADs might thus arise from architectural constraints.

Serum titers of autoantibodies against α-synuclein and tau in child- and adulthood

Autoreactive antibodies against the proteins alpha-synuclein (α-syn) and tau are detectable in body fluids of both healthy and diseased elderly people. However, nothing is known about their presence or titers in children. To close this gap and to characterize their temporary expression levels, we used ELISA techniques to investigate the serum titers of α-syn and tau reactive autoantibodies in 37 and 32 adults and 37 and 31 children, respectively. Most serum samples from the children exhibited both antibody types and interestingly, the levels were similar to those observed in the adult serum samples. Furthermore, sex-specific analysis revealed significantly increased α-syn reactive autoantibody titers in female children. The presence of α-syn and tau reactive autoantibodies in early childhood indicates that both immunoglobulins belong to the pool of naturally occurring autoantibodies (nAbs), as their antigen-independent synthesis from birth is a crucial characteristic. Due to their general participation in the maintenance of the physiological homeostasis, we hypothesize that both investigated nAbs are involved in the metabolic regulation of their specific antigen. Therefore, they may be a part of a mechanism that already exists in the innate immunological repertoire to provide protection from pathologies caused by dysregulated α-syn and tau metabolisms.

Effect of enriched housing on levels of natural (auto-)antibodies in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae

Housing of pigs in barren, stimulus-poor housing conditions may influence their immune status, including antibody responses to (auto-)antigens, and thus affect immune protection, which will influence the onset and outcome of infection. In the present study, we investigated the effects of environmental enrichment versus barren housing on the level of natural (auto-)antibodies (NA(A)b) and their isotypes (IgM and IgG) binding keyhole limpet hemocyanin (KLH), myelin basic protein (MBP), and phosphorycholine conjugated to bovine serum albumin (PC-BSA) in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae). Pigs (n = 56) were housed in either barren or enriched pens from birth to 54 days of age. They were infected with PRRSV on 44 days of age, and with A. pleuropneumoniae 8 days later. Blood samples were taken on 7 different sampling days. Housing significantly affected the overall serum levels of NA(A)b binding KLH, MBP and PC-BSA, and before infection barren housed pigs had significantly higher levels of NA(A)b than enriched housed pigs, except for KLH-IgM and PC-BSA-IgG. Infection only affected the IgM, but not the IgG isotype. Moreover, changes in MBP-IgM and PC-BSA-IgM following infection were different for enriched and barren housed pigs. These results suggest that the effect of infection on NA(A)b is influenced by housing conditions and that NA(A)b, especially IgM may be affected by infection.