Autoreactive Antibodies Research Articles

Mapping effector genes at lupus GWAS loci using promoter Capture-C in follicular helper T cells

Systemic lupus erythematosus (SLE) is mediated by autoreactive antibodies that damage multiple tissues. Genome-wide association studies (GWAS) link >60 loci with SLE risk, but the causal variants and effector genes are largely unknown. We generated high-resolution spatial maps of SLE variant accessibility and gene connectivity in human follicular helper T cells (TFH), a cell type required for anti-nuclear antibodies characteristic of SLE. Of the ~400 potential regulatory variants identified, 90% exhibit spatial proximity to genes distant in the 1D genome sequence, including variants that loop to regulate the canonical TFH genes BCL6 and CXCR5 as confirmed by genome editing. SLE ‘variant-to-gene’ maps also implicate genes with no known role in TFH/SLE disease biology, including the kinases HIPK1 and MINK1. Targeting these kinases in TFH inhibits production of IL-21, a cytokine crucial for class-switched B cell antibodies. These studies offer mechanistic insight into the SLE-associated regulatory architecture of the human genome.

Human Fcγ-receptor IIb modulates pathogen-specific versus self-reactive antibody responses in lyme arthritis.

Pathogen-specific antibody responses need to be tightly regulated to generate protective but limit self-reactive immune responses. While loss of humoral tolerance has been associated with microbial infections, the pathways involved in balancing protective versus autoreactive antibody responses in humans are incompletely understood. Studies in classical mouse model systems have provided evidence that balancing of immune responses through inhibitory receptors is an important quality control checkpoint. Genetic differences between inbred mouse models and the outbred human population and allelic receptor variants not present in mice; however, argue for caution when directly translating these findings to the human system. By studying Borrelia burgdorferi infection in humanized mice reconstituted with human hematopoietic stem cells from donors homozygous for a functional or a non-functional FcγRIIb allele, we show that the human inhibitory FcγRIIb is a critical checkpoint balancing protective and autoreactive immune responses, linking infection with induction of autoimmunity in the human immune system.

Expanded Autoantibody Profiles for Subsetting of Native American, African American, and European American Patients With Systemic Lupus Erythematosus.

ObjectiveMany Native American (NA) patients with systemic lupus erythematosus (SLE) do not exhibit the classical SLE autoantibody profiles of European American (EA) and African American (AA) patients with SLE. The poorer SLE disease outcomes noted in NA patients highlights a need for more equitable diagnostic and prognostic tools for NA patients with SLE. The objective was to identify informative autoantibody profiles for NA, AA, and EA patients with SLE using an expanded set of autoantigens.MethodsSera from 49 NA, 49 AA, and 49 EA age‐, sex‐, and antinuclear autoantibody titer–matched patients with SLE who met the American College of Rheumatology classification criteria and 10 ethnicity‐, sex‐, and age‐matched controls were tested for autoantibody reactivity by autoantigen microarrays. Autoantibodies that were significantly elevated in patients with SLE compared with ethnicity‐specific controls were selected for hierarchical clustering. Differences in clinical criteria between patient clusters were determined by Fisher's exact test and corrected for multiple comparisons.Results NA, AA, and EA patients with SLE each had a cluster distinguished by higher levels of anti‐Ro52 and another cluster distinguished by nucleic acid–specific autoantibodies. Additional clusters were distinguished in NA patients by elevated extracellular matrix autoantibodies and were distinguished in AA patients by elevated Sm/RNP autoantibody and elevated nucleolin/histone autoantibody. Two EA patient clusters with similar nucleic acid– and Ro52‐specific autoantibodies were distinguished by either high or low histone 2A reactivity. Renal manifestations trended higher in the NA Ro52 cluster and were significantly enriched in the AA nucleolin/histone cluster. The AA nucleolin/histone cluster and EA H2A cluster had higher disease activity.ConclusionExpanded autoantibody profiles can identify informative subsets of patients with SLE.

056 Systems approach to evaluate disease factors in pemphigus

Pemphigus vulgaris (PV) pathogenesis is dependent upon HLA genetic susceptibility and multiple autoantibody (autoAb) reactivities to desmoglein (Dsg) and non-Dsg targets. The relative roles of specific disease-associated factors have yet to be determined. In this study, we integrated large scale genetic and proteomic data on (1) PV-associated HLA alleles, (2) 31 autoAb specificities detected by protein array, and (3) 4 autoAb detected by ELISA (anti-Dsg3, -Dsg1, -TPO and -Tg) in 200 PV patients and 121 healthy controls (CR).

Abstract D117: Differential reactivity and cell migration inhibitory functions of autoantibodies to Enolase 1 from African American and European American men with prostate cancer

Abstract Prostate cancer (PCa) is the second leading cause of cancer-related deaths in the U.S., with African American (AA) men showing a higher mortality than European American (EA) men. While biological determinants contributing to PCa health disparities remain to be clearly established, there is growing evidence of differences in immunobiology between AA and EA patients with PCa. We demonstrated previously, using immunoproteomic profiling of anti-tumor autoantibody responses in AA and EA patients with PCa, that the glycolytic enzyme enolase 1 (ENO1) is the target of an autoantibody response in subsets of these patients. AA patient sera showed immunoreactivity to ENO1 in a panel of PCa cell lines, as detected by immunoblotting, with lack of reactivity in docetaxel (DTX)-resistant PC3 and DU145 cells. By contrast, anti-ENO1 sera from EA patients and a monoclonal anti-ENO1 antibody (MoAB-ENO1) showed immunoreactivity across the same cell line panel, including DTX-resistant cells. We also noted differences in anti-ENO1 reactivity in ELISA and immunoblots of PCa cell lysates between AA-PCa and EA-PCa patients, suggesting a race-related generation of autoantibodies to different ENO1 variants. ENO1 is a surface protein in cancer cells with roles in plasminogen activation, cell migration, and metastasis. Thus, we explored if anti-ENO1 autoantibodies from AA and EA PCa patients exerted different anti-cancer effects against DTX-sensitive and DTX-resistant PCa cells. Using cell migration assays, we observed that anti-ENO1 sera from EA patients and MoAB-ENO1 reduced the migration of DTX-resistant PC3 and DU145 cells but not that of DTX-sensitive cells. This inhibitory effect was intrinsic to the autoantibodies since purified IgG fraction produced similar results. Further, these inhibitory effects were reversed by pre-absorption of anti-ENO1 sera and purified IgG with recombinant human ENO1. Intriguingly, anti-ENO1 sera from AA patients lacked the same inhibitory effects on the migration of DTX-resistant cells, consistent with their lack of immunoreactivity to ENO1 in these cells. In addition, we observed that MoAB-ENO1, which behaves similar to the anti-ENO1 EA sera, decreased viability without evident cell death, measured by MTT assays and imaging analysis, in both DTX-sensitive and DTX-resistant cells, with a more robust effect on the latter. Together, these results suggest that anti-ENO1 autoantibodies from EA-PCa patients may exert a protective effect by decreasing the migration and proliferation of chemoresistant PCa cells. By contrast, anti-ENO1 autoantibodies from AA PCa patients may lack these protective effects, which could contribute to increased cancer cell migration and metastasis. Further studies are needed to dissect the molecular basis for this race-related differential anti-ENO1 immunoreactivity in PCa patients, and exploit the immunotherapeutic potential of anti-ENO1 antibodies for the treatment of chemoresistant PCa. Citation Format: Carlos Diaz-Osterman, Tino Sanchez, Carlos A Casiano. Differential reactivity and cell migration inhibitory functions of autoantibodies to Enolase 1 from African American and European American men with prostate cancer [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D117.

Association Between Centromere- and Topoisomerase-specific Immune Responses and the Degree of Microangiopathy in Systemic Sclerosis.

Autoreactive antibody responses, including the use of several isotypes of autoantibodies, have been shown to be associated with clinical outcome in several rheumatic autoimmune diseases. The goals of this study were to evaluate whether (1) anticentromere antibody (ACA)- and antitopoisomerase antibody (ATA)-specific isotype expression, and (2) organ involvement are associated with the degree of microangiopathy in systemic sclerosis (SSc). ACA and ATA IgG, IgM, and IgA levels were measured in baseline serum samples of ACA IgG-positive (+) and ATA IgG+ patients with SSc. The degree of microangiopathy was determined based on nailfold videocapillaroscopy (NVC) images collected at the same point in time. Logistic regression analyses with autoantibodies, clinical characteristics, isotype expression, and ACA and ATA IgG, IgM, and IgA levels as independent variables, and NVC pattern as the dependent variable were performed. In 164 patients, isotype levels and degree of microangiopathy were evaluated. Logistic regression confirmed the association of the degree of microangiopathy with the presence of digital ulcers (OR 3.07, 95% CI 1.43-6.60), interstitial lung disease (OR 3.41, 95% CI 1.11-10.61), and pulmonary arterial hypertension (OR 5.58, 95% CI 2.05-17.81). ATA positivity was associated with more severe microangiopathy (OR 2.09, 95% CI 1.05-4.13). Patients who expressed solely ACA IgG showed a trend towards less severe microangiopathy compared to patients also expressing ACA IgM and/or IgA. Levels of ACA IgG and ATA IgM were found to be associated with microangiopathy severity. We observed an association between ACA and ATA responses and the degree of microangiopathy in SSc. These findings might indicate that the breadth of the autoimmune response, as reflected by autoantibody production and microvascular damage, interacts in the pathophysiology of SSc.

Identification of Novel Native Autoantigens in Rheumatoid Arthritis.

The majority of patients diagnosed with rheumatoid arthritis (RA) have developed autoantibodies against neoepitopes in proteins that have undergone post-translational modification, e.g., citrullination or carbamylation. There is growing evidence of their molecular relevance and their potential utility to improve diagnosis, patient stratification, and prognosis for precision medicine. Autoantibodies reacting to native proteins may also have a role in RA pathogenesis, however, their reactivity patterns remain much less studied. We hypothesized that a high-density protein array technology could shed light onto the normal and disease-related autoantibodies produced in healthy and RA patient subgroups. In an exploratory study, we investigated the global reactivity of autoantibodies in plasma pools from 15 anti-cyclic citrullinated peptide (CCP)-positive and 10 anti-CCP-negative RA patients and 10 healthy donors against more than 1600 native and unmodified human proteins using a high-density protein array. A total of 102 proteins recognized by IgG autoantibodies were identified, hereof 86 were recognized by antibodies from CCP-positive RA patients and 76 from anti-CCP-negative RA patients, but not by antibodies from healthy donors. Twenty-four of the identified autoantigens have previously been identified in synovial fluid. Multiple human proteins in their native conformation are recognized by autoantibodies from anti-CCP-positive as well as anti-CCP-negative RA patients.

Total and double-stranded DNA-specific immunoglobulin E in bronchoalveolar lavage fluid of children with human adenovirus pneumonia

BackgroundSome antibodies and autoreactive antibodies are associated with the severity of infectious diseases. The roles of humoral responses to lung inflammation in children with human adenovirus (HAdVs) pneumonia remain unknown. Patients and methodsA retrospective study was done to compare plasma immunoglobulin E (IgE) levels between HAdVs pneumonia patients and healthy children by searching the electronic medical record system of Guangzhou Women and Children's Medical Center. Then, a prospective study was performed for children with HAdVs pneumonia who needed flexible bronchoscopy for examination and treatment purposes during July 2017 to July 2019. We examined the IgE and autoreactive IgE levels in plasma and bronchoalveolar lavage fluid (BALF) of these children to explore their role in HAdVs pneumonia. ResultsA significantly higher level of IgE was found in plasma from children hospitalized with HAdVs pneumonia compared with that from healthy children in the same age range. Furthermore, the levels of IgE, double-stranded DNA (dsDNA), and double-stranded DNA-specific immunoglobulin E (dsDNA-IgE) in BALF were increased compared to plasma in children with HAdVs pneumonia. The levels of IgE, dsDNA, and dsDNA-IgE in BALF were significantly higher in the severe group compared to the non-severe group. The ability of IgE in BALF to recognize dsDNA was verified by the ELISPOT test. ConclusionsOur findings indicate that IgE and dsDNA-IgE in BALF may contribute to lung injury caused by HAdVs, especially in severe cases. Elevated dsDNA-IgE may serve as an indicator of severity in children with HAdVs pneumonia.

Autoantibodies as predictors for survival and immune-related adverse events in checkpoint inhibition therapy of metastasized melanoma.

10011 Background: Increasing evidence suggests that the B cell response in cancer patients is an important component of anti-tumour immunity. Autoantibodies targeting tumour and self-antigens may serve as biomarkers of anti-tumour and auto-immunity. As they can be measured in patient' sera, they have great potential as clinical routine biomarkers. The objective of this study was to explore if autoantibodies are associated with survival and immune related adverse events (irAE) in patients with metastatic melanoma under checkpoint inhitibor (CPI) therapy. Methods: Pre-treatment serum samples from 333 metastatic melanoma patients receiving CPI therapy at 5 European centers were retrospectively used to identify autoantibody signatures for survival and irAE. We designed a cancer immunotherapy antigen array comprising 832 autoimmune and tumour antigens as well as immune and cancer pathway proteins. Statistical tests were separately performed for patients treated with anti-CTLA4 (alone or in combination) and with anti-PD1 antibody monotherapy. Cox-regression analysis and univariate statistical tests were applied for biomarker discovery. Progression free and overall survival was measured from treatment initiation to tumor progression or death date. irAE were recorded including onset date and grade (CTC-AE). Results: For each therapy group we identified a set of autoantibody reactivities in untreated melanoma patients that were associated with the development of irAEs and/or survival. The identified autoantibodies target a diverse set of antigens comprising neoantigens (p53), cancer testis antigens (MAGEB4), paraneoplastic antigens (gephyrin), autoantigens (ribosomal proteins, Nor-90) and FGFR1. Autoantigens that correlated with irAE and survival were e.g. anti-MAGEB4 and anti-FGFR1. Elevated anti-MAGEB4 pre-treatment levels were associated with longer overall survival (p = 0.002, HR = 0.77) and the development of irAEs (p = 0.002, HR = 1.27) in ipilimumab +/- nivolumab treated patients. Higher pre-treatment anti-FGFR1 antibodies were associated with shorter survival (p = 0.008, HR = 1.27) and a lower a lower frequency of irAEs (p = 0.04, HR = 0.69) in these patients. Conclusions: We identified autoantibody targets suggesting a diverse B cell response to antigens expressed in tumours and those associated with autoimmunity. Depending on the specific antigen, the immune response towards those antigens may be associated with anti-tumour or pro-tumour responses.

Production of Autoreactive Heavy Chain-Only Antibodies in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is characterized by the overproduction of high-affinity autoreactive antibodies. Here, we show that more than 65.8% of 222 recombinant antibodies derived from 8 SLE patients can be secreted as heavy chain-only antibodies (HCAbs) when expressed in HEK-293T cells. The secretion of HCAbs follows the conventional endoplasmic reticulum-Golgi apparatus pathway, despite triggering a weaker unfolded protein response (UPR). Many of the purified SLE HCAbs remain autoreactive and have an even higher affinity for dsDNA, Sm, nucleosome, and cardiolipin than HCAbs from healthy individuals. Extended analyses of the CDR3 region and the heavy chain variable (VH) region of HCAb F3 show that the VH region is responsible for IgH secretion, while the CDR3 region determines its reactivity. Such a high frequency of HCAb secretion cannot fully concur with our current understanding of antibody assembly and secretion. The presence of a large proportion of autoreactive HCAbs in SLE reveals a novel mechanism for the generation of autoreactive antibodies in lupus.

Immune-mediated axonal dysfunction in seropositive and seronegative primary Sjögren's syndrome.

ObjectiveThe present study investigates the peripheral neuropathy in Primary Sjögren's syndrome (pSS) using the nerve excitability test to further elucidate how peripheral nerves are affected by the autoantibodies.MethodsEach patient received clinical evaluation, examination for anti‐SSA/Ro and anti‐SSB/La antibodies titer, paired motor and sensory nerve excitability test, thermal quantitative sensory test (QST), and nerve conduction study (NCS).ResultsA total of 40 pSS patients wasenrolled. Motor axonal study of the pSS with positive anti‐SSA/Ro or anti‐SSB/La antibodies (n = 28) was found to have increased stimulus for 50% compound muscle action potential (CMAP) (P < 0.05), increased rheobase (P < 0.01), increased minimum I/V slope (P < 0.01) and hyperpolarizing I/V slope (P < 0.05), increased relative refractory period (RRP, P < 0.001), decreased accommodation of threshold electrotonus toward depolarizing current (P < 0.05), and increased accommodation toward hyperpolarizing current (P < 0.05). Seronegative pSS (n = 10) showed much less prominent motor axonal changes, showing only increased minimum I/V slope (P < 0.05). Sensory axonal study in seropositive pSS patients is found to have increased stimulus for 50% sensory nerve action potential (SNAP) (P < 0.01), decreased latency (P < 0.01), increased RRP (P < 0.01), and increased subexcitability (P < 0.05). Seronegative pSS patients have shown no significant sensory axonal changes. Thermal QST showed more prominent abnormalities in seronegative pSS compared to seropositive pSS.InterpretationAnti‐SSA/Ro and anti‐SSB/La autoantibodies might cause dysfunction in nodal and internodal region of the axon and small nerve fibers; meanwhile, autoreactive antibodies in seronegative pSS mainly affect small nerve fibers. Thus, the underlying pathophysiology for the two types of pSS is different.

Immune tolerance limits effective immunity to epitopes targeted by universal influenza vaccines

Abstract A universal influenza vaccine could save millions of lives in the event of a deadly pandemic. It is not clear why antibodies specific for conserved regions of influenza viruses are so rare. One possibility is that these antibodies have a higher potential to cross-react to self-proteins, and therefore B cells that generate these antibodies are deleted through tolerance mechanisms. Therefore, we examined whether cross-reactive influenza antibodies had a higher potential to be autoreactive than antibodies specific for one subtype of influenza. We previously demonstrated that H3N2-vaccinated mice treated with a low dose of rapamycin had more cross-reactive influenza antibodies and were better protected against subsequent lethal infections of multiple subtypes. Thus, we utilized rapamycin to increase the frequency of influenza cross-reactive antibodies, and tested whether these antibodies were more reactive to self-proteins than strain-specific antibodies. We found that mice with increased levels of cross-reactive influenza antibodies also had more IgM antibodies specific for self-antigens. Importantly, the increase in autoreactive IgM antibodies correlated with increased susceptibility to disease in mouse models of multiple sclerosis, lupus, and Guillian-Barre Syndrome. Together, our results suggest that influenza cross-reactive antibodies have the potential to be autoreactive. These data have important implications for developing universal influenza vaccines designed to generate durable influenza cross-reactive antibodies.

Advances in the role of helper T cells in autoimmune diseases.

Autoimmune diseases are primary immune diseases in which autoreactive antibodies or sensitized lymphocytes destroy and damage tissue and cellular components, resulting in tissue damage and organ dysfunction. Helper T cells may be involved in the pathogenesis of autoimmune diseases under certain conditions. This review summarizes recent research on the role of helper T cells in autoimmune diseases from two aspects, helper T cell-mediated production of autoantibodies by B cells and helper T cell-induced activation of abnormal lymphocytes, and provides ideas for the treatment of autoimmune diseases. The abnormal expression of helper T cells promotes the differentiation of B cells that produce autoantibodies, which leads to the development of different diseases. Among them, abnormal expression of Th2 cells and T follicular helper cells is more likely to cause antibody-mediated autoimmune diseases. In addition, abnormal activation of helper T cells also mediates autoimmune diseases through the production of abnormal cytokines and chemokines. Helper T cells play an essential role in the pathogenesis of autoimmune diseases, and a full understanding of their role in autoimmune diseases is helpful for providing ideas for the treatment of autoimmune diseases.

Metabolic Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Not Due to Anti-mitochondrial Antibodies.

Metabolic profiling studies have recently indicated dysfunctional mitochondria in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). This includes an impaired function of pyruvate dehydrogenase complex (PDC), possibly driven by serum factor(s), which leads to inadequate adenosine triphosphate generation and excessive lactate accumulation. A reminiscent energy blockade is likely to occur in primary biliary cholangitis (PBC), caused by anti-PDC autoantibodies, as recently proposed. PBC is associated with fatigue and post-exertional malaise, also signifying ME/CFS. We herein have investigated whether ME/CFS patients have autoreactive antibodies that could interfere with mitochondrial function. We found that only 1 of 161 examined ME/CFS patients was positive for anti-PDC, while all PBC patients (15/15) presented significant IgM, IgG, and IgA anti-PDC reactivity, as previously shown. None of fibromyalgia patients (0/14), multiple sclerosis patients (0/29), and healthy blood donors (0/44) controls showed reactivities. Anti-mitochondrial autoantibodies (inner and outer membrane) were negative in ME/CFS cohort. Anti-cardiolipin antibody levels in patients did not differ significantly from healthy blood donors. In conclusion, the impaired mitochondrial/metabolic dysfunction, observed in ME/CFS, cannot be explained by presence of circulating autoantibodies against the tested mitochondrial epitopes.

Autoantibodies against the prion protein in individuals with PRNP mutations

To determine whether naturally occurring autoantibodies against the prion protein are present in individuals with genetic prion disease mutations and controls, and if so, whether they are protective against prion disease. In this case-control study, we collected 124 blood samples from individuals with a variety of pathogenic PRNP mutations and 78 control individuals with a positive family history of genetic prion disease but lacking disease-associated PRNP mutations. Antibody reactivity was measured using an indirect ELISA for the detection of human immunoglobulin G1-4 antibodies against wild-type human prion protein. Multivariate linear regression models were constructed to analyze differences in autoantibody reactivity between (1) PRNP mutation carriers vs controls and (2) asymptomatic vs symptomatic PRNP mutation carriers. Robustness of results was examined in matched cohorts. We found that antibody reactivity was present in a subset of both PRNP mutation carriers and controls. Autoantibody levels were not influenced by PRNP mutation status or clinical manifestation of prion disease. Post hoc analyses showed anti-PrPC autoantibody titers to be independent of personal history of autoimmune disease and other immunologic disorders, as well as PRNP codon 129 polymorphism. Pathogenic PRNP variants do not notably stimulate antibody-mediated anti-PrPC immunity. Anti-PrPC immunoglobulin G autoantibodies are not associated with the onset of prion disease. The presence of anti-PrPC autoantibodies in the general population without any disease-specific association suggests that relatively high titers of naturally occurring antibodies are well-tolerated. NCT02837705.

Pregnancy with Myasthenia Gravis

ABSTRACTMyasthenia Gravis (MG) is a serious autoimmune disease, but now can be treated. Symptoms include weakness and fatigue in voluntary muscles caused by an autoantibody reaction to nicotinic acetylcholine receptor (AChR) at the post synapse of the neuromuscular junction. Pregnancy can affect autoimmune diseases so that pregnancy can aggravate MG disease. On the other hand it is also reported that pregnancy does not affect and can even improve MG disease. In this article, We report a 27-year-old woman who was diagnosed with myasthenia gravis that having a pregnancy. Initially she had no problems with pregnancy. Patients underwent pregnancy by taking the drug Mestinon four times daily and roborant. But entering the 33rd-34th week, the examination results showed that the pregnancy experienced oligohydramnios and Intrauterine Growth Retardation (IUGR), it was probably caused by malnutrition. Then we decided to end the patient's pregnancy with a Caesarean section. The operation went well, born to a baby boy / 2450grams / Apgar Score 5-7. Observation for one week the mother's condition continued to improve. Diplopia and weaknesses also improve. Likewise the baby showed a healthy condition. The patient was discharged while still taking MG drugs that had been previously consumed. This case report showed that pregnancy worsened MG disease, but MG did not affect pregnancy.Keywords : Pregnancy, Myasthenia Gravis

Self-Antigens Displayed on Liposomal Nanoparticles above a Threshold of Epitope Density Elicit Class-Switched Autoreactive Antibodies Independent of T Cell Help.

Epitope density has a profound impact on B cell responses to particulate Ags, the molecular mechanisms of which remain to be explored. To dissect the role of epitope density in this process, we have synthesized a series of liposomal particles, similar to the size of viruses, that display a model self-antigen peptide at defined surface densities. Immunization of C57BL/6J mice using these particles elicited both IgM and class-switched IgG1, IgG2b, and IgG3 autoreactive Abs that depended on the epitope density. In C57BL/6 gene knockout mice lacking either functional TCRs or MHC class II molecules on B cells, the liposomal particles also elicited IgM, IgG1, IgG2b, and IgG3 responses that were comparable in magnitudes to wild-type mice, suggesting that this B cell response was independent of cognate T cell help. Notably, the titer of the IgG in wild-type animals could be increased by more than 200-fold upon replacement of liposomes with bacteriophage Qβ virus-like particles that displayed the same self-antigen peptide at comparable epitope densities. This enhancement was lost almost completely in gene knockout mice lacking either TCRs or MHC class II molecules on B cells. In conclusion, epitope density above a threshold on particulate Ags can serve as a stand-alone signal to trigger secretion of autoreactive and class-switched IgG in vivo in the absence of cognate T cell help or any adjuvants. The extraordinary immunogenicity of Qβ viral-like particles relies, in large part, on their ability to effectively recruit T cell help after B cell activation.

Age-Related Changes in B Cells Relevant to Vaccine Responses.

Older people have reduced immune responses to infection and vaccination. B cell activation is key for the efficacy of the vaccine response, but there are several age-related changes in B cells which may contribute to the loss of vaccine efficacy. Different subpopulations of B cells have different functions and phenotypes. These populations can change as we age; older people have been shown to have fewer "IgM memory" cells, regulatory B cells and plasma cells and more IgD-CD27- "double-negative" and "age-related B cells." While the overall quantity of antibody in the blood does not change, the quality of the B cell response changes; producing less specific antibodies upon challenge and more autoreactive antibodies. This could be due to changes in selection pressures, as has been demonstrated by repertoire sequencing of different subsets of B cells at different ages. Other changes in antibody repertoire are seen, including greater levels of IgG2 in older people and altered IgG1 IGHV gene usage. Since B cells rely on their environment for efficient responses, some of these changes may be due to age-related changes in accessory cells/signals. Other changes appear to be intrinsic to older/aged B cells themselves, such as their tendency to produce greater levels of inflammatory cytokines.

Serological comparison of systemic lupus erythematosus with neuropsychiatric lupus using synthetic nucleic acid antigens

Neuropsychiatric systemic lupus erythematosus is an autoimmune disorder characterized by an irregular exchange between the central nervous system and the immune system, leading to the outbreak of neurological conditions with possible disabling effects. Although neuropsychiatric systemic lupus erythematosus is the most common expression of lupus condition, it is still poorly understood. In this study, we focus on the development of an advantageous method based on the application of synthetic nucleic acids and protein-based antigen arrays in order to characterize autoreactive antibodies in neuropsychiatric systemic lupus erythematosus. We confirmed the benefits of using synthetic oligonucleotides such as assay reproducibility, elevated affinity and specificity to autoreactive antibodies. We also demonstrated presence of autoantibodies towards three particular synthetic double stranded antigens and verify similarity of antinuclear antibody patterns in ordinary lupus and neuropsychiatric systemic lupus erythematosus.

Activated PI3Kδ breaches multiple B cell tolerance checkpoints and causes autoantibody production.

Antibody-mediated autoimmune diseases are a major health burden. However, our understanding of how self-reactive B cells escape self-tolerance checkpoints to secrete pathogenic autoantibodies remains incomplete. Here, we demonstrate that patients with monogenic immune dysregulation caused by gain-of-function mutations in PIK3CD, encoding the p110δ catalytic subunit of phosphoinositide 3-kinase (PI3K), have highly penetrant secretion of autoreactive IgM antibodies. In mice with the corresponding heterozygous Pik3cd activating mutation, self-reactive B cells exhibit a cell-autonomous subversion of their response to self-antigen: instead of becoming tolerized and repressed from secreting autoantibody, Pik3cd gain-of-function B cells are activated by self-antigen to form plasmablasts that secrete high titers of germline-encoded IgM autoantibody and hypermutating germinal center B cells. However, within the germinal center, peripheral tolerance was still enforced, and there was selection against B cells with high affinity for self-antigen. These data show that the strength of PI3K signaling is a key regulator of pregerminal center B cell self-tolerance and thus represents a druggable pathway to treat antibody-mediated autoimmunity.