SARS-CoV-2 infection induces cross-reactive autoantibodies against angiotensin II

Patients infected with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV- 2) can experience life-threatening respiratory distress, blood pressure dysregulation and thrombosis. This is thought to be associated with an impaired activity of angiotensin- converting enzyme-2 (ACE-2), which is the main entry receptor of SARS-CoV-2 and which also tightly regulates blood pressure by converting the vasoconstrictive peptide angiotensin II (AngII) to a vasopressor peptide. Here, we show that a significant proportion of hospitalized COVID-19 patients developed autoantibodies against AngII, whose presence correlates with lower blood oxygenation, blood pressure dysregulation, and overall higher disease severity. Anti-AngII antibodies can develop upon specific immune reaction to the SARS-CoV-2 proteins Spike or RBD, to which they can cross- bind, suggesting some epitope mimicry between AngII and Spike/RBD. These results provide important insights on how an immune reaction against SARS-CoV-2 can impair blood pressure regulation.

Design and Synthesis of HCV-E2 Glycoprotein Epitope Mimics in Molecular Construction of Potential Synthetic Vaccines

Hepatitis C virus remains a global threat, despite the availability of highly effective direct-acting antiviral (DAA) drugs. With thousands of new infections annually, the need for a prophylactic vaccine is evident. However, traditional vaccine design has been unable to provide effective vaccines so far. Therefore, alternative strategies need to be investigated. In this work, a chemistry-based approach is explored towards fully synthetic peptide-based vaccines using epitope mimicry, by focusing on highly effective and conserved amino acid sequences in HCV, which, upon antibody binding, inhibit its bio-activity. Continuous and discontinuous epitope mimics were both chemically synthesized based on the HCV-E2 glycoprotein while using designed fully synthetic cyclic peptides. These cyclic epitope mimics were assembled on an orthogonally protected scaffold. The scaffolded epitope mimics have been assessed in immunization experiments to investigate the elicitation of anti-HCV-E2 glycoprotein antibodies. The neutralizing potential of the elicited antibodies was investigated, representing a first step in employing chemically synthesized epitope mimics as a novel strategy towards vaccine design.

Antibody mediated epitope mimicry in the pathogenesis of Zika virus related disease

The association of Guillain-Barré syndrome with Zika virus infection raises suspicion of autoimmunity in the pathogenesis of Zika associated disease. Using computational analysis to identify predicted B and T cell epitopes, we assessed whether antibodies elicited by B cell epitopes in Zika virus may also target B cell epitopes in the human proteome. We detected amino acid motifs predicted to be B cell epitopes in Zika virus proteins which are also present in human proteins, including pro-neuropeptide Y (proNPY), NAV2 and other proteins with interacting neurophysiologic function. We examine the predicted MHC binding of peptides likely to provide T cell help to the potential mimic epitopes. Some potential mimic epitopes in Zika virus envelope have apparently strong T cell help, likely facilitating immunoglobulin class switch. We also identify epitope mimic commonalities with dengue serotypes 1 and 3. We hypothesize that antibodies to Zika virus epitopes may contribute to the pathogenesis of Zika-associated Guillain-Barré syndrome, microcephaly, and ocular lesions, and may be a driver of autoimmunity. The risk associated with responses to potential epitope mimics must be addressed in the development of vaccines and therapeutics for Zika virus infections.

In Vivo Efficacy of Peptide-Derived B Cell Receptor (BCR) Targeted Therapy In a Disseminated Burkitt′s Lymphoma Xenograft Modell

Abstract 3924 Targeted therapies in terms of monoclonal antibodies have become standard in the treatment of various lymphomas. Albeit being more specific than conventional therapy, the used antibodies target surface receptors both present on polyclonal and monoclonal hematopoietic cells. Due to its specificity for the malignant B-cell clone the B-cell receptor (BCR) is an ideal therapeutic target in lymphoma therapy. Moreover, using peptides has several advantages over whole antibodies: reduced immunogenicity, better epitope mimicry and tissue penetration, easier synthesis and more favourable pharmacokinetics (no uptake into the reticulo-endothelial system). Peptides mimicking the epitope recognized by lymphoma BCRs have therefore been praised as promising therapeutic tools for years (Lam, West J Med., 1993) but a proof-of-concept has only been published recently in mice bearing subcutaneous A20 lymphoma (Palmieri et al., Blood, 2010). In the current study, we have established a human cell line-derived disseminated Burkitt′s lymphoma model (SUP-B8) in NOD/SCID mice by intravenous injection. Our active principle was the tetramerized BCR binding peptide YSFEDLYRRGGK-biotin (termed T-peptide, Renschler et al., PNAS, 1994) which was applied intravenously on day (d) 12, 14, 16 and 19 after injection of the tumor cells, respectively. The therapeutic efficacy was evaluated in comparison to several control groups (tetramerized control peptide (termed C-peptide, RDYSYERLFGGK-biotin), vehicle (0.8% ACN in water, 200μl/d) and untreated animals). Tumor cell engraftment was monitored via daily surveillance of disease symptoms, FACS (anti-human lambda, CD19, anti-murine CD45) and fluorescence-based in vivo imaging system (FI, Kodak FX, Alexa750 labeled anti-human CD45) on days 12 and 21. SUP-B8 engrafted predominantly in the bone marrow (BM, take rate = 100%) and marrow infiltration increased in untreated mice between start and end of therapy from 1 ± 0.4% (d 12) to 39.8 ± 9.4% (d 21). Other sites of engraftment were subcutis (38%) and spleen (8%). The examined compounds were well tolerated in tumor-bearing mice, no acute toxicity could be observed and maximal body weight loss was below 15%. Treatment of xenograft mice with the tetramerized BCR-binding peptide significantly reduced bone marrow infiltration compared to controls (T-peptide 8.1 ± 4.6%, C-peptide: 32.8 ± 8%, p=0.037, vehicle: 30.5 ± 7.9%, p=0.029). Considering the short half-life of uncoupled peptides and the injection schedule every second day, this is a remarkable reduction. For further optimization of this promising therapeutic approach we plan to couple peptides to effector molecules via acid labile linkers; this is based on the evidence that confocal imaging of Burkitt lymphoma cell lines showed the processing of specific BCR binding peptides in acidic organelles of the cell. In summary, we conclude that BCR targeted peptide-based therapy is a feasible method with remarkable therapeutic results in vivo and future studies will focus on coupling specific peptides to appropriate effector molecules or combinational therapeutic approaches using conventional chemotherapeutics. Disclosures: No relevant conflicts of interest to declare.