A synthetic delivery vector for mucosal vaccination (preprint)

The success of mRNA-based vaccines during the Covid-19 pandemic has highlighted the value of this new platform for vaccine development against infectious disease. However, the CD8+ T cell response remains modest with mRNA vaccines, and these do not induce mucosal immunity, which would be needed to prevent viral spread in the healthy population. To address this drawback, we developed a dendritic cell targeting mucosal vaccination vector, the homopentameric STxB. Here, we describe the highly efficient chemical synthesis of the protein, and its in vitro folding. This straightforward preparation led to a synthetic delivery tool whose biophysical and intracellular trafficking characteristics were largely indistinguishable from recombinant STxB. The chemical approach allowed for the generation of new variants with bioorthogonal handles. Selected variants were chemically coupled to several types of antigens derived from the mucosal viruses SARS-CoV-2 and type 16 human papillomavirus. Upon intranasal administration in mice, mucosal immunity, including resident memory CD8+ T cells and IgA antibodies was induced against these antigens. Our study thereby identifies a novel synthetic antigen delivery tool for mucosal vaccination with an unmatched potential to respond to an urgent medical need.

Omicron BA.1 breakthrough infection drives long-term remodeling of the memory B cell repertoire in vaccinated individuals. (preprint)

How infection by a viral variant showing antigenic drift impacts a preformed mature human memory B cell (MBC) repertoire remains an open question. Here, we studied the MBC response up to 6 months after Omicron BA.1 breakthrough infection in individuals previously vaccinated with three doses of mRNA vaccine. Longitudinal analysis, using single-cell multi-omics and functional analysis of monoclonal antibodies from RBD-specific MBCs, revealed that a BA.1 breakthrough infection mostly recruited pre-existing cross-reactive MBCs with limited de novo response against BA.1-restricted epitopes. Reorganization of clonal hierarchy and new rounds of germinal center reaction, however, combined to maintain diversity and induce progressive maturation of the MBC repertoire against common Hu-1 and BA.1, but not BA.5-restricted, SARS-CoV-2 Spike RBD epitopes. Such remodeling was further associated with marked improvement in overall neutralizing breadth and potency. These findings have fundamental implications for the design of future vaccination booster strategies.

Potent Human Broadly SARS-CoV-2 Neutralizing IgA and IgG Antibodies Effective Against Omicron BA.1 and BA.2 (preprint)

Memory B-cell and antibody responses to the SARS-CoV-2 spike protein contribute to long-term immune protection against severe COVID-19, which can also be prevented by antibody-based interventions. Here, wide SARS-CoV-2 immunoprofiling in COVID-19 convalescents combining serological, cellular and monoclonal antibody explorations, revealed humoral immunity coordination. Detailed characterization of a hundred SARS-CoV-2 spike memory B-cell monoclonal antibodies uncovered diversity in their repertoire and antiviral functions. The latter were influenced by the targeted spike region with strong Fc-dependent effectors to the S2 subunit and potent neutralizers to the receptor binding domain. Amongst those, Cv2.1169 and Cv2.3194 antibodies cross-neutralized SARS-CoV-2 variants of concern including Omicron BA.1 and BA.2. Cv2.1169, isolated from a mucosa-derived IgA memory B cell, demonstrated potency boost as IgA dimers and therapeutic efficacy as IgG antibodies in animal models. Structural data provided mechanistic clues to Cv2.1169 potency and breadth. Thus, potent broadly neutralizing IgA antibodies elicited in mucosal tissues can stem SARS-CoV-2 infection, and Cv2.1169 and Cv2.3194 are prime candidates for COVID-19 prevention and treatment.

Immune escape of SARS-CoV-2 Omicron variant from mRNA vaccination-elicited RBD-specific memory B cells. (preprint)

Memory B cells (MBCs) represent a second layer of immune protection against SARS-CoV-2. Whether MBCs elicited by mRNA vaccines can recognize the Omicron variant is of major concern. We used bio-layer interferometry to assess the affinity against the receptor-binding-domain (RBD) of Omicron spike of 313 naturally expressed monoclonal IgG that were previously tested for affinity and neutralization against VOC prior to Omicron. We report here that Omicron evades recognition from a larger fraction of these antibodies than any of the previous VOCs. Additionally, whereas 30% of these antibodies retained high affinity against Omicron-RBD, our analysis suggest that Omicron specifically evades antibodies displaying potent neutralizing activity against the D614G and Beta variant viruses. Further studies are warranted to understand the consequences of a lower memory B cell potency on the overall protection associated with current vaccines.

Telmisartan for treatment of Covid-19 patients: An open multicenter randomized clinical trial.

Background: Angiotensin receptor blockers (ARBs), such as telmisartan, have been postulated to treat Covid-19-induced lung inflammation. Methods: This is a parallel-group, randomized, two-arm, open-label, adaptive, multicenter superiority trial with 1:1 allocation ratio. Participants included patients from 18 years of age hospitalized with Covid-19 with 4 or fewer days since symptom onset enrolled at a university and a community hospital in Buenos Aires, Argentina. Exclusion criteria included prior intensive care unit (ICU) admission and use of ARBs/angiotensin converting enzyme inhibitors at randomization. Control arm received standard care alone and treatment arm telmisartan 80 mg twice daily for 14 days. Primary outcomes were C-reactive protein (CRP) plasma levels at day 5 and 8 after randomization. Secondary outcomes included time to discharge within 15 days, admission to ICU and death at 15- and 30-days. NCT04355936 (Completed). Findings: A pragmatic decision to end the study before the third interim analysis was made on Oct. 30th due to sharp reduction in recruitment. A total of 162 patients were randomized. 158 patients enrolled between May 14 and October 30 2020, were included in the analysis, 80 in the standard care and 78 in the telmisartan added to standard care group. Baseline absolute CRP serum levels were 5.53 ± 6.19 mg/dL (95% CI 6.91 to 4.15, n = 80) and 9.04 ± 7.69 (95% CI 9.04 to 10.82, n = 74) in the standard care and telmisartan added to standard care groups, respectively. Day 5 control-group CRP levels were 6.06 ± 6.95 mg/dL (95% CI 7.79-4.35, n = 66) while telmisartan group were 3.83 ± 5.08 mg/dL (95% CI 5.08-2.59, n = 66, p = 0.038). Day 8 CRP levels were 6.30 ± 8.19 mg/dL (95% CI 8.79-3.81, n = 44) and 2.37 ± 3.47 mg/dL (95% CI 3.44-1.30, n = 43, p = 0.0098) in the control and telmisartan groups, respectively (all values expressed as mean ± SD). Kaplan-Meier analysis showed that telmisartan-treated patients had a lower median time-to-discharge (control=15 days; telmisartan=9 days). Death by day 30 was reduced in the telmisartan-treated group (control 22.54%, 16/71; telmisartan 4.29%, 3/70 participants; p = 0.0023). Composite ICU, mechanical ventilation or death was reduced by telmisartan treatment at days 15 and 30. No adverse events were reported. Interpretation: Our study suggests that the ARB telmisartan, a widely used antihypertensive drug, is safe and could reduce morbidity and mortality in hospitalized patients infected with SARS -CoV-2 by anti-inflammatory effects. Further studies employing telmisartan are needed for confirmation of our results and to define its true therapeutic value as a tool against Covid-19.

Memory B cells control SARS-CoV-2 variants upon mRNA vaccination of naive and COVID-19 recovered individuals. (preprint)

How a previous SARS-CoV-2 infection may amplify and model the memory B cell (MBC) response elicited by mRNA vaccines was addressed by a comparative longitudinal study of two cohorts, naive individuals and disease-recovered patients, up to 2 months after vaccination. The quality of the memory response was assessed by analysis of the VDJ repertoire, affinity and neutralization against variants of concerns (VOC), using unbiased cultures of 2452 MBCs. Upon boost, the MBC pool of recovered patients selectively expanded, further matured and harbored potent neutralizers against VOC. Maturation of the MBC response in naive individuals was much less pronounced. Nevertheless, and as opposed to their weaker neutralizing serum response, half of their RBD-specific MBCs displayed high affinity towards multiple VOC and one-third retained neutralizing potency against B.1.351. Thus, repeated vaccine challenges could reduce these differences by recall of affinity-matured MBCs and allow naive vaccinees to cope efficiently with VOC.

SARS-CoV-2 tracheitis in laryngectomized patients: a consecutive case-series study. (preprint)

Key points • SARS-CoV-2 is a possible cause of acute severe tracheitis in laryngectomees. • In our series, the clinical picture was characterized by a hemorrhagic tracheitis with a slow resolution pattern. • We observed a histological pattern of erosive inflammation of the respiratory epithelium. • Planned tracheo-bronchoscopy and tracheal toilettes are recommended to prevent critical obstruction of the airway, which can be fatal in patients with associated impairment of lung function caused by SARS-CoV-2 infection. • The present cases highlight the need for close interdisciplinary working and communication in the management of airway complications of COVID-19 infection.

Maturation and persistence of the anti-SARS-CoV-2 memory B cell response. (preprint)

Memory B cells play a fundamental role in host defenses against viruses, but to date, their role have been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 Spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory B cells, including preexisting cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and largely contributed to the late remarkably stable memory B-cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6 months after SARS-CoV-2 infection and may provide long-term protection.

Telmisartan for treatment of Covid-19 patients: an open randomized clinical trial. Preliminary report. (preprint)

Background. Covid-19, the disease caused by SARS-CoV-2, is associated with significant respiratory-related morbidity and mortality. Angiotensin receptor blockers (ARBs) have been postulated as tentative pharmacological agents to treat Covid-19-induced lung inflammation. Trial design. This trial is a parallel group, randomized, two arm, open label, multicenter superiority trial with 1:1 allocation ratio. Methods. Participants included patients who were 18 years of age or older and who had been hospitalized with confirmed Covid-19 with 4 or fewer days since symptom onset. Exclusion criteria included intensive care unit admission prior to randomization and use of angiotensin receptor blocker or angiotensin converting enzyme inhibitors at admission. Participants in the treatment arm received telmisartan 80 mg bid during 14 days plus standard care. Participants in the control arm received standard care alone. Primary outcome was to achieve significant reductions in plasma levels of C-reactive protein in telmisartan treated Covid-19 patients at day 5 and 8 after randomization. Key secondary outcomes included time to discharge evaluated at 15 days after randomization and admission to ICU and death at 15- and 30-days post randomization. We present here a preliminary report. Results. A total of 78 patients were included in the interim analysis, 40 in the telmisartan and 38 in the control groups. CRP levels at day 5 in the control group were 51.1 +/- 44.8 mg/L (mean +/- SD; n=28) and in the telmisartan group were 24.2 +/- 31.4 mg/L (mean +/- SD; n=32, p<0.05). At day 8, CRP levels were 41.6 +/- 47.6 mg/L (mean +/- SD; n=16) and 9.0 +/- 10.0 mg/L (mean +/- SD; n=13, p < 0.05) in the control and telmisartan groups, respectively. Also, analysis of time to discharge by Kaplan-Meier method showed that telmisartan treated patients had statistically significant lower time to discharge (median time to discharge control group=15 days; telmisartan group=9 days). No differences were observed for ICU admission or death. No significant adverse events related to telmisartan were reported. Conclusions. In the present preliminary report, despite the small number of patients studied, ARB telmisartan, a well-known inexpensive safe antihypertensive drug, administered in high doses, demonstrates anti-inflammatory effects and improved morbidity in hospitalized patients infected with SARS -CoV-2, providing support for its use in this serious pandemia (NCT04355936).

HIGH VERSUS STANDARD DOSES OF CORTICOSTEROIDS IN COVID-19 PATIENTS WITH AN ACUTE RESPIRATORY DISTRESS SYNDROME: a controlled observational comparative study. (preprint)

INTRODUCTION: Despite the increasing evidence of the benefit of corticosteroids for the treatment of moderate-severe Coronavirus disease 2019 (COVID-19) patients, no data are available about the potential role of high doses of steroids for these patients. METHODS: All consecutive confirmed COVID-19 patients admitted to a single center were selected, including those treated with steroids and an acute respiratory distress syndrome (ARDS). Patients were allocated to the high doses (HD, 250mg/day or more of methylprednisolone) of corticosteroids or the standard doses (SD, 1.5mg/kg/day or more of methylprednisolone) at discretion of treating physician. The primary endpoint was the mortality between both cohorts and secondary endpoints were the risk of need for mechanical ventilation (MV) or death and the risk of developing a severe ARDS. RESULTS: 573 patients were included: 428 (74.7%) men, with a median (IQR) age of 64 (54-73) years. In HD cohort, a worse baseline respiratory situation was observed and male sex, older age and comorbidities were significantly more common. After adjusting by baseline characteristics, HD were associated with a higher mortality than SD (adjusted-OR 2.46, 95% CI 1.58-3.83, p<0.001) and with an increased risk of needing MV or death (adjusted-OR 2.50, p=0.001). Conversely, the risk of developing a severe ARDS was similar between groups. Interaction analysis showed that HD increased mortality exclusively in elderly patients. CONCLUSION: Our real-world experience advises against exceeding 1-1.5mg/kg/day of corticosteroids for severe COVID-19 with an ARDS, especially in older subjects. This reinforces the rationale of modulating rather than suppressing immune responses in these patients.