Appearance of IgG to SARS-CoV-2 in saliva effectively indicates seroconversion in mRNA vaccinated immunocompromised individuals

BackgroundImmunocompromised individuals are highly susceptible to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Whether vaccine-induced immunity in these individuals involves the oral cavity, a primary site of infection, is presently unknown. MethodsImmunocompromised individuals (n=404) and healthy controls (n=82) participated in a prospective clinical trial encompassing two doses of the mRNA BNT162b2 vaccine. Immunocompromised individuals included primary immunodeficiencies (PID) and secondary immunodeficiencies caused by human immunodeficiency virus (HIV) infection, allogeneic hematopoietic stem cell transplantation (HSCT)/chimeric antigen receptor T cell therapy (CAR-T), solid organ transplantation (SOT), and chronic lymphocytic leukemia (CLL). Saliva and serum samples were collected at four time points from the first vaccine dose until 2 weeks after second dose. SARS-CoV-2 spike specific immunoglobulin G (IgG) responses were quantified by a multiplex bead-based assay in saliva and correlated to paired serum IgG titers determined by Elecsys(R) Anti-SARS-CoV-2 S assay. ResultsIgG responses to the SARS-CoV-2 spike full-length trimeric glycoprotein (Spike-f) and S1 subunit in saliva in the HIV and HSCT/CAR-T groups were comparable to healthy controls. In contrast, PID, SOT, and CLL patients all displayed weaker responses which were mainly influenced by disease parameters or immunosuppressants. Salivary IgG levels strongly correlated with serum IgG titers on days 21 and 35 (rho=0.8079 and 0.7768, p=<0.0001). Receiver operating characteristic curve analysis for the predictive power of salivary IgG yielded AUC=0.95, PPV=90.7% for the entire cohort on D35. ConclusionsSaliva conveys humoral responses induced by BNT162b2 vaccination. The predictive power makes it highly suitable for screening low responding/vulnerable groups for revaccination. Trial RegistrationClinicalTrials.gov Identifier: NCT04780659 FundingKnut and Alice Wallenberg Foundation, Erling Perssons family foundation, Region Stockholm, Swedish Research Council, Karolinska Institutet, The Swedish Blood Cancer Foundation and the organization for PID patient group in Sweden, and Nordstjernan AB. Center for Medical Innovation (CIMED), the Swedish Medical Research Council and the Stockholm County Council (ALF). GRAPHIC ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/21264377v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1428efcorg.highwire.dtl.DTLVardef@b97e88org.highwire.dtl.DTLVardef@224661org.highwire.dtl.DTLVardef@3ab25a_HPS_FORMAT_FIGEXP M_FIG C_FIG

Safety and efficacy of the mRNA BNT162b2 vaccine against SARS-CoV-2 in five groups of immunocompromised patients and healthy controls in a prospective open-label clinical trial

BackgroundPatients with immunocompromised disorders have mainly been excluded from clinical trials of vaccination against COVID-19. Thus, the aim of this prospective clinical trial was to investigate the safety and efficacy after two doses of BNT162b2 mRNA vaccination in five selected groups of immunocompromised patients and healthy controls. Methods539 study subjects (449 patients and 90 controls) were included in the clinical trial. The patients had either primary (n=90), or secondary immunodeficiency disorders due to human immunodeficiency virus infection (n=90), allogeneic hematopoietic stem cell transplantation/chimeric antigen receptor T cell therapy (n=90), solid organ transplantation (SOT) (n=89), or chronic lymphocytic leukemia (CLL) (n=90). The primary endpoint was seroconversion rate two weeks after the second dose. The secondary endpoints were safety and documented SARS-CoV-2 infection. FindingsAdverse events were generally mild, but one case of fatal suspected unexpected serious adverse reaction occurred. 72{middle dot}2% of the immunocompromised patients seroconverted compared to 100% of the controls (p=0.004). Lowest seroconversion rates were found in the SOT (43{middle dot}4%) and CLL (63{middle dot}3%) patient groups with observed negative impact of treatment with mycophenolate mofetil and ibrutinib, respectively. InterpretationThe results showed that the mRNA BNT162b2 vaccine was safe in immunocompromised patients. The rate of seroconversion was substantially lower than in healthy controls, with a wide range of rates and antibody titres among predefined patient groups and subgroups. This clinical trial highlights the need for additional vaccine doses in certain immunocompromised patient groups and/or subgroups to improve immunity. FundingKnut and Alice Wallenberg Foundation, Nordstjernan AB, Region Stockholm, Swedish Research Council, Karolinska Institutet, and organizations for PID/CLL-patients in Sweden.

Longitudinal characterization of humoral and cellular immunity in hospitalized COVID-19 patients reveal immune persistence up to 9 months after infection

BackgroundInsights into early, specific humoral and cellular responses to infection with SARS-CoV-2, as well as the persistence and magnitude of resulting immune memory is important amidst the ongoing pandemic. The combination of humoral and cellular immunity will most likely contribute to protection from reinfection or severe disease. MethodsHere, we conducted a longitudinal study on hospitalized moderate and severe COVID-19 patients from the acute phase of disease into convalescence at five- and nine-months post symptom onset. Utilizing flow cytometry, serological assays as well as B cell and T cell FluoroSpot assays, we assessed the magnitude and specificity of humoral and cellular immune memory during and after human SARS-CoV-2 infection. FindingsDuring acute COVID-19, we observed an increase in germinal center activity, a substantial expansion of antibodysecreting cells, and the generation of SARS-CoV-2-neutralizing antibodies. Despite gradually decreasing antibody levels, we show persistent, neutralizing antibody titers as well as robust specific memory B cell responses and polyfunctional T cell responses at five- and nine-months after symptom onset in both moderate and severe COVID-19 patients. Long-term SARS-CoV-2 specific responses were marked by preferential targeting of spike over nucleocapsid protein. ConclusionsOur findings describe the initiation and, importantly, persistence of cellular and humoral SARS-CoV-2 specific immunological memory in hospitalized COVID-19 patients long after recovery, likely contributing towards protection against reinfection.

Distinct lung-homing receptor expression and activation profiles on NK cell and T cell subsets in COVID-19 and influenza

Respiratory viral infections with SARS-CoV-2 or influenza viruses commonly induce a strong infiltration of immune cells into the lung, with potential detrimental effects on the integrity of the lung tissue. Despite comprising the largest fractions of circulating lymphocytes in the lung, little is known about how blood natural killer (NK) cells and T cell subsets are equipped for lung-homing in COVID-19 and influenza. Using 28-colour flow cytometry and re-analysis of published RNA-seq datasets, we provide a detailed comparative analysis of NK cells and T cells in peripheral blood from moderately sick COVID-19 and influenza patients, focusing on the expression of chemokine receptors known to be involved in leukocyte recruitment to the lung. The results reveal a predominant role for CXCR3, CXCR6, and CCR5 in COVID-19 and influenza patients, mirrored by scRNA-seq signatures in peripheral blood and bronchoalveolar lavage from publicly available datasets. NK cells and T cells expressing lung-homing receptors displayed stronger phenotypic signs of activation as compared to cells lacking lung-homing receptors, and activation was overall stronger in influenza as compared to COVID-19. Together, our results indicate migration of functionally competent CXCR3+, CXCR6+, and/or CCR5+ NK cells and T cells to the lungs in moderate COVID-19 and influenza patients, identifying potential common targets for future therapeutic interventions in respiratory viral infections. Author summaryThe composition of in particular CXCR3+ and/or CXCR6+ NK cells and T cells is altered in peripheral blood upon infection with SARS-CoV-2 or influenza virus in patients with moderate disease. Lung-homing receptor-expression is biased towards phenotypically activated NK cells and T cells, suggesting a functional role for these cells co-expressing in particular CXCR3 and/or CXCR6 upon homing towards the lung.

High-dimensional profiling reveals phenotypic heterogeneity and disease-specific alterations of granulocytes in COVID-19

Since the outset of the COVID-19 pandemic, increasing evidence suggests that the innate immune responses play an important role in the disease development. A dysregulated inflammatory state has been proposed as key driver of clinical complications in COVID-19, with a potential detrimental role of granulocytes. However, a comprehensive phenotypic description of circulating granulocytes in SARS-CoV-2-infected patients is lacking. In this study, we used high-dimensional flow cytometry for granulocyte immunophenotyping in peripheral blood collected from COVID-19 patients during acute and convalescent phases. Severe COVID-19 was associated with increased levels of both mature and immature neutrophils, and decreased counts of eosinophils and basophils. Distinct immunotypes were evident in COVID-19 patients, with altered expression of several receptors involved in activation, adhesion and migration of granulocytes (e.g. CD62L, CD11a/b, CD69, CD63, CXCR4). Paired sampling revealed recovery and phenotypic restoration of the granulocytic signature in the convalescent phase. The identified granulocyte immunotypes correlated with distinct sets of soluble inflammatory markers supporting pathophysiologic relevance. Furthermore, clinical features, including multi-organ dysfunction and respiratory function, could be predicted using combined laboratory measurements and immunophenotyping. This study provides a comprehensive granulocyte characterization in COVID-19 and reveals specific immunotypes with potential predictive value for key clinical features associated with COVID-19. SignificanceAccumulating evidence shows that granulocytes are key modulators of the immune response to SARS-CoV-2 infection and their dysregulation could significantly impact COVID-19 severity and patient recovery after virus clearance. In the present study, we identify selected immune traits in neutrophil, eosinophil and basophil subsets associated to severity of COVID-19 and to peripheral protein profiles. Moreover, computational modeling indicates that the combined use of phenotypic data and laboratory measurements can effectively predict key clinical outcomes in COVID-19 patients. Finally, patient-matched longitudinal analysis shows phenotypic normalization of granulocyte subsets 4 months after hospitalization. Overall, in this work we extend the current understanding of the distinct contribution of granulocyte subsets to COVID-19 pathogenesis.

MAIT cell activation and dynamics associated with COVID-19 disease severity and outcome

Severe COVID-19 is characterized by excessive inflammation of the lower airways. The balance of protective versus pathological immune responses in COVID-19 is incompletely understood. Mucosa-associated invariant T (MAIT) cells are antimicrobial T cells that recognize bacterial metabolites, and can also function as innate-like sensors and mediators of antiviral responses. Here, we investigated the MAIT cell compartment in COVID-19 patients with moderate and severe disease, as well as in convalescence. We show profound and preferential decline in MAIT cells in circulation of patients with active disease paired with strong activation, as well as significant MAIT cell enrichment and pro-inflammatory IL-17A bias in the airways. Unsupervised analysis identified MAIT cell CD69high and CXCR3low immunotypes associated with poor clinical outcome. MAIT cell levels normalized in the convalescent phase, consistent with dynamic recruitment to the tissues and subsequent release with disease resolution. These findings indicate that MAIT cells are engaged in the immune response against SARS-CoV-2 and suggest their involvement in COVID-19 immunopathogenesis. One sentence summaryMAIT cells are strongly activated by SARS-CoV-2 infection in a manner associated with disease severity and outcome, they decline in blood, are enriched in the airways as a prominent IL-17A expressing subset, and dynamically recover in circulation during convalescence.

Natural killer cell activation related to clinical outcome of COVID-19

Understanding innate immune responses in COVID-19 is important for deciphering mechanisms of host responses and interpreting disease pathogenesis. Natural killer (NK) cells are innate effector lymphocytes that respond to acute viral infections, but might also contribute to immune pathology. Here, using 28-color flow cytometry, we describe a state of strong NK cell activation across distinct subsets in peripheral blood of COVID-19 patients, a pattern mirrored in scRNA-seq signatures of lung NK cells. Unsupervised high-dimensional analysis identified distinct immunophenotypes that were linked to disease severity. Hallmarks of these immunophenotypes were high expression of perforin, NKG2C, and Ksp37, reflecting a high presence of adaptive NK cell expansions in circulation of patients with severe disease. Finally, arming of CD56bright NK cells was observed in course of COVID-19 disease states, driven by a defined protein-protein interaction network of inflammatory soluble factors. This provides a detailed map of the NK cell activation-landscape in COVID-19 disease.

Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19

ABSTRACTSARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. We systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in a large cohort of unexposed individuals as well as exposed family members and individuals with acute or convalescent COVID-19. Acute phase SARS-CoV-2-specific T cells displayed a highly activated cytotoxic phenotype that correlated with various clinical markers of disease severity, whereas convalescent phase SARS-CoV-2-specific T cells were polyfunctional and displayed a stem-like memory phenotype. Importantly, SARS-CoV-2-specific T cells were detectable in antibody-seronegative family members and individuals with a history of asymptomatic or mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits robust memory T cell responses akin to those observed in the context of successful vaccines, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19 also in seronegative individuals.Competing Interest StatementThe authors have declared no competing interest.View Full Text