Abstract
Anti-dsDNA antibodies are a hallmark of systemic lupus erythematosus and are highly associated with its exacerbation. Cumulative evidence has suggested that somatic hypermutation contributes ...to the high-affinity reactivity of anti-dsDNA antibodies. Our previous study demonstrated that these antibodies are generated from germline precursors with low-affinity ssDNA reactivity through affinity maturation and clonal expansion in patients with acute lupus. This raised the question of whether such precursors could be subjected to immune tolerance. To address this, we generated a site-directed knock-in (KI) mouse line, G9gl, which carries germline-reverted sequences of the VH–DH–JH and Vκ–Jκ regions of patient-derived, high-affinity anti-dsDNA antibodies. G9gl heterozygous mice had a reduced number of peripheral B cells, only 27% of which expressed G9gl B-cell receptor (BCR). The remaining B cells harbored non-KI allele-derived immunoglobulin heavy (IgH) chains or fusion products of upstream mouse VH and the KI gene, suggesting that receptor editing through VH replacement occurred in a large proportion of B cells in the KI mice. G9gl BCR-expressing B cells responded to ssDNA but not dsDNA, and exhibited several anergic phenotypes, including reduced surface BCR and shortened life span. Furthermore, G9gl B cells were excluded from germinal centers (GCs) induced by several conditions. In particular, following immunization with methylated bovine serum albumin-conjugated bacterial DNA, G9gl B cells occurred at a high frequency in memory B cells but not GC B cells or plasmablasts. Collectively, multiple tolerance checkpoints prevented low-affinity precursors of pathogenic anti-dsDNA B cells from undergoing clonal expansion and affinity maturation in GCs.
Regulation of anti-dsDNA antibodies in SLE
Graphical Abstract
Chronic rhinosinusitis with nasal polyposis (CRSwNP) is characterized by eosinophilic inflammation and polyposis at the nose and paranasal sinus and a high concentration of IgE in nasal polyps (NPs). ...The causative antigen and pathogenesis of CRSwNP remain unknown.
We aimed to identify reactive allergens of IgE antibodies produced locally in NPs of patients with CRSwNP. We also attempted to unravel the differentiation pathway of IgE-producing B cells in NPs.
IgE reactivity of patients with CRSwNP was investigated by characterizing single cell–derived mAbs. T-cell response against identified allergens was investigated in vitro. NP-infiltrating lymphocytes were characterized by using flow cytometry. Immunoglobulins expressed in NPs were analyzed by using high-throughput DNA sequencing for immunoglobulin.
About 20% of isolated IgE antibodies derived from NP-residing plasmablasts specifically recognized surface determinants of nasal bacteria, such as Staphylococcus aureus, Streptococcus pyogenes, and Haemophilus influenzae. A TH2 response against S pyogenes was observed in patients with CRSwNP. Flow cytometric analysis revealed sizable germinal center B–like cell and plasmablast subsets expressing IgE on the cell surface in NPs. High-throughput DNA sequencing immunoglobulin analysis highlighted the clonal connectivity of IgE with IgG and IgA1. The Iε-Cα1 circle transcript was detected in NPs.
In patients with CRSwNP, nasal bacteria–reactive B cells differentiate into IgE-producing B cells through IgG/IgA1-IgE class switching, suggesting that allergic conversion of the mucosal response against nasal bacteria underlies disease pathogenesis.
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The evolutional process of disease-associated autoantibodies in systemic lupus erythematosus (SLE) remains to be established. Here we show intraclonal diversification and affinity maturation of ...anti-nuclear antibody (ANA)-producing B cells in SLE. We identified a panel of monoclonal ANAs recognizing nuclear antigens, such as double-stranded DNA (dsDNA) and ribonucleoproteins (RNPs) from acute SLE subjects. These ANAs had relatively few, but nonetheless critical mutations. High-throughput immunoglobulin sequencing of blood lymphocytes disclosed the existence of sizable ANA lineages shearing critical mutations intraclonally. We further focused on anti-DNA antibodies, which are capable to bind to both single-stranded (ss) and dsDNA at high affinity. Crystal structure and biochemical analysis confirmed a direct role of the mutations in the acquisition of DNA reactivity and also revealed that these anti-DNA antibodies recognized an unpaired region within DNA duplex. Our study unveils the unique properties of high-affinity anti-DNA antibodies that are generated through antigen-driven affinity maturation in acute phase of SLE.
Streptococcus agalactiae serotype distribution and its antibiotic susceptibility affect disease prevention strategies, but the serotype distribution varies among patient groups. The objectives of ...this study were to establish the group B Streptococcus (GBS) serotype distribution in patients from Egypt and to assess antibiotic sensitivity of invasive GBS isolates. A total of 490 patients participated in this multicenter study; 160 had urinary tract infection, 115 complained of diabetic foot ulcers, 125 men had genital tract infections, and 30 women females had genital tract infections. Others had bronchopneumonia, otitis media, synovitis, or meningitis. Serotyping of the isolated GBS was performed at the CDC in the United States. Antibiotic sensitivity patterns were determined using the disk diffusion method. In men, the most common serotypes were II, III, and V, whereas types Ia, II, III, and V were isolated from women. Macrolides (erythromycin) resistance occurred in 4.1% of the isolates; 10.2% were resistant to both clindamycin and inducible resistance of macrolides, lincomycin, and streptogramin; 17.3% were resistant to quinolones; and 95.9% were resistant to tetracyclines. GBS primarily infected the urinary tract, skin, soft tissue, and genital tract in both genders. Isolates were sensitive to beta-lactam drugs, vancomycin, and linezolid; 14.0% were resistant to macrolides with or without clindamycin. Only 6.0% of the strains were sensitive to tetracyclines. Although GBS causes invasive infections in Egyptian adults, it rarely causes neonatal meningitis or sepsis. Future studies should determine whether GBS isolates are transmitted sexually, by performing a follow-up study of the partner of the infected patient.
Introduction
Covid‐19 is linked with the development of cardio‐metabolic disorders, including dyslipidemia, dysregulation of high‐density lipoprotein (HDL), and low‐density lipoprotein (LDL). ...Furthermore, SARS‐Co‐2 infection is associated with noteworthy changes in lipid profile, which is suggested as a possible biomarker to support the diagnosis and management of Covid‐19.
Methods
This paper adopts the literature review method to obtain information about how Covid‐19 affects high‐risk group patients and may cause severe and critical effects due to the development of acute lung injury and acute respiratory distress syndrome. A narrative and comprehensive review is presented.
Results
Reducing HDL in Covid‐19 is connected to the disease severity and poor clinical outcomes, suggesting that high HDL serum levels could benefit Covid‐19. SARS‐CoV‐2 binds HDL, and this complex is attached to the co‐localized receptors, facilitating viral entry. Therefore, SARS‐CoV‐2 infection may induce the development of dysfunctional HDL through different mechanisms, including induction of inflammatory and oxidative stress with activation of inflammatory signaling pathways. In turn, the induction of dysfunctional HDL induces the activation of inflammatory signaling pathways and oxidative stress, increasing Covid‐19 severity.
Conclusions
Covid‐19 is linked with the development of cardio‐metabolic disorders, including dyslipidemia in general and dysregulation of high‐density lipoprotein and low‐density lipoprotein. Therefore, the present study aimed to overview the causal relationship between dysfunctional high‐density lipoprotein and Covid‐19.
While Covid‐19 is linked with the development of cardio‐metabolic disorders, including dyslipidemia and dysregulation of high‐density lipoprotein and low‐density lipoprotein, this study aimed to overview the causal relationship between dysfunctional high‐density lipoprotein and Covid‐19.
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