Identification of Natural Bispecific Antibodies against Cyclic Citrullinated Peptide and Immunoglobulin G in Rheumatoid Arthritis

BACKGROUND: Previous studies indicate that natural bispecific antibodies can be readily produced in vivo when the body is simultaneously stimulated with 2 distinct antigens. Patients with rheumatoid arthritis (RA) usually exhibit persistent immune responses to various autoantigens, raising the possibility that natural bispecific antibodies against 2 distinct autoantigens might exist. METHODOLOGY/PRINCIPAL FINDINGS: We identified the presence of natural bispecific antibodies against cyclic citrullinated peptide (CCP) and immunoglobulin G (IgG) in RA patients' sera by means of a double-antigen sandwich enzyme-linked immunosorbent assay (ELISA). The spontaneous emergence of bispecific antibodies was confirmed by mixing different proportions of 1 anti-CCP-positive serum and 1 rheumatoid factor (RF)-positive serum in vitro. Among the tested samples, positive correlations were found between the presence of bispecific antibodies and both IgG4 anti-CCP antibodies and IgG4 RF (r = 0.507, p<0.001 and r = 0.249, p = 0.044, respectively), suggesting that the IgG4 subclass is associated with this phenomenon. Furthermore, bispecific antibodies were selectively generated when several anti-CCP- and RF-positive sera were mixed pairwise, indicating that factors other than the monospecific antibody titers may also contribute to the production of the natural bispecific antibodies. CONCLUSIONS/SIGNIFICANCE: We successfully identified the presence of natural bispecific antibodies. Our results suggest that these antibodies originate from anti-CCP and RF in the sera of RA patients. The natural occurrence of bispecific antibodies in human diseases may provide new insights for a better understanding of the diseases. Further investigations are needed to elucidate their precise generation mechanisms and explore their clinical significance in disease development and progression in a larger study population

DH and JH usage in murine fetal liver mirrors that of human fetal liver

In mouse and human, the regulated development of antibody repertoire diversity during ontogeny proceeds in parallel with the development of the ability to generate antibodies to an array of specific antigens. Compared to adult, the human fetal antibody repertoire limits N addition and uses specifically positioned VDJ gene segments more frequently, including V6-1 the most DH-proximal VH, DQ52, the most JH-proximal DH, and JH2, which is DH-proximal. The murine fetal antibody repertoire also limits the incorporation of N nucleotides and uses its most DH proximal VH, VH81X, more frequently. To test whether DH and JH also follow the pattern observed in human, we used the scheme of Hardy to sort B lineage cells from BALB/c fetal and neonatal liver, RT-PCR cloned and sequenced VH7183-containing VDJCμ transcripts, and then assessed VH7183-DH-JH and complementary determining region 3 of the immunoglobulin heavy chain (CDR-H3) content in comparison to the previously studied adult BALB/c mouse repertoire. Due to the deficiency in N nucleotide addition, perinatal CDR-H3s manifested a distinct pattern of amino acid usage and predicted loop structures. As in the case of adult bone marrow, we observed a focusing of CDR-H3 length and CDR-H3 loop hydrophobicity, especially in the transition from the early to late pre-B cell stage, a developmental checkpoint associated with expression of the pre-B cell receptor. However, fetal liver usage of JH-proximal DHQ52 and DH-proximal JH2 was markedly greater than that of adult bone marrow. Thus, the early pattern of DH and JH usage in mouse feta liver mirrors that of human

Increased Immune Complexes of Hypocretin Autoantibodies in Narcolepsy

International audienceBACKGROUND: Hypocretin peptides participate in the regulation of sleep-wake cycle while deficiency in hypocretin signaling and loss of hypocretin neurons are causative for narcolepsy-cataplexy. However, the mechanism responsible for alteration of the hypocretin system in narcolepsy-cataplexy and its relevance to other central hypersomnias remain unknown. Here we studied whether central hypersomnias can be associated with autoantibodies reacting with hypocretin-1 peptide present as immune complexes. METHODOLOGY: Serum levels of free and dissociated (total) autoantibodies reacting with hypocretin-1 peptide were measured by enzyme-linked immunosorbent assay and analyzed with regard to clinical parameters in 82 subjects with narcolepsy-cataplexy, narcolepsy without cataplexy or idiopathic hypersomnia and were compared to 25 healthy controls. PRINCIPAL FINDINGS: Serum levels of total but not free IgG autoantibodies against hypocretin-1 were increased in narcolepsy-cataplexy. Increased levels of complexed IgG autoantibodies against hypocretin-1 were found in all patients groups with a further increase in narcolepsy-cataplexy. Levels of total IgM hypocretin-1 autoantibodies were also elevated in all groups of patients. Increased levels of anti-idiotypic IgM autoantibodies reacting with hypocretin-1 IgG autoantibodies affinity purified from sera of subjects with narcolepsy-cataplexy were found in all three groups of patients. Disease duration correlated negatively with serum levels of hypocretin-1 IgG and IgM autoantibodies and with anti-idiotypic IgM autoantibodies. CONCLUSION: Central hypersomnias and particularly narcolepsy-cataplexy are characterized by higher serum levels of autoantibodies directed against hypocretin-1 which are present as immune complexes most likely with anti-idiotypic autoantibodies suggesting their relevance to the mechanism of sleep-wake cycle regulation

The role of alveolar type II cells in swine leptospirosis

Abstract: This study aimed to investigate a possible relationship between alveolar type II cells and the inflammatory response to infection with Leptospira spp., and thus comprise a further element that can be involved in the pathogenesis of lung injury in naturally infected pigs. The study group consisted of 73 adult pigs that were extensively reared and slaughtered in Teresina, Piauí state, and Timon, Maranhão state, Brazil. The diagnosis of leptospirosis was made using the microscopic agglutination test (MAT) aided by immunohistochemistry and polymerase chain reaction. The MAT registered the occurrence of anti-Leptospira antibodies in 10.96% (8/73) of the pigs. Immunohistochemistry allowed for the visualization of the Leptospira spp. antigen in the lungs of 87.67% (64/73) of the pigs. There was hyperplasia of bronchus-associated lymphoid tissue and circulatory changes, such as congestion of alveolar septa, parenchymal hemorrhage and edema within the alveoli. Lung inflammation was more intense (p = 0.0312) in infected animals, which also showed increased thickening of the alveolar septa (p = 0.0006). Evaluation of alveolar type II (ATII) cells using an anti-TTF-1 (Thyroid Transcription Factor-1) antibody showed that there were more immunostained cells in the non-infected pigs (53.8%) than in the infected animals (46.2%) and that there was an inverse correlation between TTF-1 positive cells and the inflammatory infiltrate. There was no amplification of Leptospira DNA in the lung samples, but leptospiral DNA amplification was observed in the kidneys. The results of this study showed that a relationship exists between a decrease in alveolar type II cells and a leptospire infection. Thus, this work points to the importance of studying the ATII cells as a potential marker of the level of lung innate immune response during leptospirosis in pigs

Self-assembled nanogel made of mannan : synthesis and characterization

Amphiphilic mannan (mannan-C16) was synthesized by the Michael addition of hydrophobic 1-hexadecanethiol (C16) to hydroxyethyl methacrylated mannan (mannan-HEMA). Mannan-C16 formed nanosized aggregates in water by selfassembly via the hydrophobic interaction among C16molecules as confirmed by hydrogen nuclearmagnetic resonance (1H NMR), fluorescence spectroscopy, cryo-field emission scanning electron microscopy (cryo-FESEM), and dynamic light scattering (DLS). The mannan-C16 critical aggregation concentration (cac), calculated by fluorescence spectroscopy with Nile red and pyrene, ranged between 0.04 and 0.02mg/mL depending on the polymer degree of substitution ofC16 relative to methacrylated groups. Cryo-FESEM micrographs revealed that mannan-C16 formed irregular spherical macromolecular micelles, in this work designated as nanogels, with diameters ranging between 100 and 500 nm. The influence of the polymer degree of substitution, DSHEMA andDSC16, on the nanogel size and zeta potential was studied byDLS at different pH values and ionic strength and as a function of mannan-C16 and urea concentrations. Under all tested conditions, the nanogel was negatively charged with a zeta potential close to zero. Mannan-C16 with higher DSHEMA and DSC16 values formed larger nanogels andwere also less stable over a 6month storage period and at concentrations close to the cac.When exposed to solutions of different pH and aggressive conditions of ionic strength and urea concentration, the size of mannan-C16 varied to some extent but was always in the nanoscale range.International Iberian Nanotechnology Laboratory (INL)Fundação para a Ciência e a Tecnologia (FCT

Serum tumor markers in pediatric osteosarcoma: a summary review

Osteosarcoma is the most common primary high-grade bone tumor in both adolescents and children. Early tumor detection is key to ensuring effective treatment. Serum marker discovery and validation for pediatric osteosarcoma has accelerated in recent years, coincident with an evolving understanding of molecules and their complex interactions, and the compelling need for improved pediatric osteosarcoma outcome measures in clinical trials. This review gives a short overview of serological markers for pediatric osteosarcoma, and highlights advances in pediatric osteosarcoma-related marker research within the past year. Studies in the past year involving serum markers in patients with pediatric osteosarcoma can be assigned to one of four categories, i.e., new approaches and new markers, exploratory studies in specialized disease subsets, large cross-sectional validation studies, and longitudinal studies, with and without an intervention

Disposable sensors in diagnostics, food and environmental monitoring

Disposable sensors are low‐cost and easy‐to‐use sensing devices intended for short‐term or rapid single‐point measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resource‐limited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemo‐ and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of low‐cost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities

Clinical Use and Therapeutic Potential of IVIG/SCIG, Plasma-Derived IgA or IgM, and Other Alternative Immunoglobulin Preparations

Intravenous and subcutaneous immunoglobulin preparations, consisting of IgG class antibodies, are increasingly used to treat a broad range of pathological conditions, including humoral immune deficiencies, as well as acute and chronic inflammatory or autoimmune disorders. A plethora of Fab- or Fc-mediated immune regulatory mechanisms has been described that might act separately or in concert, depending on pathogenesis or stage of clinical condition. Attempts have been undertaken to improve the efficacy of polyclonal IgG preparations, including the identification of relevant subfractions, mild chemical modification of molecules, or modification of carbohydrate side chains. Furthermore, plasma-derived IgA or IgM preparations may exhibit characteristics that might be exploited therapeutically. The need for improved treatment strategies without increase in plasma demand is a goal and might be achieved by more optimal use of plasma-derived proteins, including the IgA and the IgM fractions. This article provides an overview on the current knowledge and future strategies to improve the efficacy of regular IgG preparations and discusses the potential of human plasma-derived IgA, IgM, and preparations composed of mixtures of IgG, IgA, and IgM