Activation of the AIM2 Receptor in Circulating Cells of Post-COVID-19 Patients With Signs of Lung Fibrosis Is Associated With the Release of IL-1α, IFN-α and TGF-ß.

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), responsible for COVID-19, has caused a global pandemic. Observational studies revealed a condition, herein called as Long-COVID syndrome (PC), that affects both moderately and severely infected patients, reducing quality-of-life. The mechanism/s underlying the onset of fibrotic-like changes in PC are still not well defined. The goal of this study was to understand the involvement of the Absent in melanoma-2 (AIM2) inflammasome in PC-associated lung fibrosis-like changes revealed by chest CT scans. Peripheral blood mononuclear cells (PBMCs) obtained from PC patients who did not develop signs of lung fibrosis were not responsive to AIM2 activation by Poly dA:dT. In sharp contrast, PBMCs from PC patients with signs of lung fibrosis were highly responsive to AIM2 activation, which induced the release of IL-1α, IFN-α and TGF-ß. The recognition of Poly dA:dT was not due to the activation of cyclic GMP-AMP (cGAMP) synthase, a stimulator of interferon response (cGAS-STING) pathways, implying a role for AIM2 in PC conditions. The release of IFN-α was caspase-1- and caspase-4-dependent when AIM2 was triggered. Instead, the release of pro-inflammatory IL-1α and pro-fibrogenic TGF-ß were inflammasome independent because the inhibition of caspase-1 and caspase-4 did not alter the levels of the two cytokines. Moreover, the responsiveness of AIM2 correlated with higher expression of the receptor in circulating CD14+ cells in PBMCs from patients with signs of lung fibrosis.

Age-related Differences in Immune Reactions to SARS-CoV-2 Spike and Nucleocapsid Antigens.

BACKGROUND/AIM: The manifestation and severity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections show a clear correlation to the age of a patient. The younger a person, the less likely the infection results in significant illness. To explore the immunological characteristics behind this phenomenon, we studied the course of SARS-CoV-2 infections in 11 households, including 8 children and 6 infants/neonates of women who got infected with SARS-CoV-2 during pregnancy. MATERIALS AND METHODS: We investigated the immune responses of peripheral blood mononuclear cells (PBMCs), umbilical cord blood mononuclear cells (UCBCs), and T cells against spike and nucleocapsid antigens of SARS-COV-2 by flow cytometry and cytokine secretion assays. RESULTS: Upon peptide stimulation, UCBC from neonates showed a strongly reduced IFN-γ production, as well as lower levels of IL-5, IL-13, and TNF-α alongside with decreased frequencies of surface CD137/PD-1 co-expressing CD4+ and CD+8 T cells compared with adult PBMCs. The PBMC response of older children instead was characterized by elevated frequencies of IFN-γ+ CD4+ T cells, but significantly lower levels of multiple cytokines (IL-5, IL-6, IL-9, IL-10, IL-17A, and TNF-α) and a marked shift of the CD4+/CD8+ T-cell ratio towards CD8+ T cells in comparison to adults. CONCLUSION: The increased severity of SARS-CoV-2 infections in adults could result from the strong cytokine production and lower potential to immunomodulate the excessive inflammation, while the limited IFN-γ production of responding T cells in infants/neonates and the additional higher frequencies of CD8+ T cells in older children may provide advantages during the course of a SARS-CoV-2 infection.

Chilblains observed during the COVID-19 pandemic cannot be distinguished from classic, cold-related chilblains

Background: Type 1 interferon (IFN-I) response induced by SARS-CoV-2 has been hypothesized to explain the association between chilblain lesions (CL) and SARS-CoV-2 infection. Objective: To explore direct cytopathogenicity of SARS-CoV-2 in CL and to focus on IFN-I expression in patients with chilblains. Materials & Methods: A monocentric cohort of 43 patients presenting with CL from April 2020 to May 2021 were included. During this period, all CL were, a priori, considered to be SARS-CoV-2-related. RT-qPCR on nasopharyngeal swabs and measurements of anti-SARS-CoV-2 antibodies were performed. Anti-SARS-CoV-2 immunostainings as well as SARS-CoV-2 RT-qPCR were performed on biopsy specimens of CL and controls. Expression of MX1 and IRF7 was analysed on patients' biopsy specimens and/or PBMC and compared with controls and/or chilblains observed before the pandemic. Serum IFN-α was also measured. Results: RT-qPCR was negative in all patients and serological tests were positive in 11 patients. Immunostaining targeting viral proteins confirmed the lack of specificity. SARS-CoV-2 RNA remained undetected in all CL specimens. MX1 immunostaining was positive in CL and in pre-pandemic chilblains compared to controls. MX1 and IRF7 expression was significantly increased in CL specimens but not in PBMC. Serum IFN-α was undetected in CL patients. Conclusion: CL observed during the pandemic do not appear to be directly related to SARS-CoV-2 infection, either based on viral cytopathogenicity or high IFN-I response induced by the virus.

SARS-CoV-2 Immunization Orchestrates the Amplification of IFNγ-Producing T Cell and NK Cell Persistence.

A successful vaccination would represent the most efficient means to control the pandemic of Coronavirus Disease-19 (COVID-19) that led to millions of deaths worldwide. Novel mRNA-based vaccines confer protective immunity against SARS-CoV-2, but whether immunity is immediately effective and how long it will remain in recipients are uncertain. We sought to assess the effectiveness of a two-dose regimen since the boosts are often delayed concerning the recommended intervals. Methods: A longitudinal cohort of healthcare workers (HCW, N = 46; 30.4% men; 69.6% women; mean age 36.05 ± 2.2 years) with no SARS-CoV-2 infection as documented by negative polymerase chain reaction was immunophenotyped in PBMC once a week for 4 weeks from the prime immunization (Pfizer mRNA BNT162b2) and had received 2 doses, to study the kinetic response. Results: We identified three risk groups to develop SARS-CoV-2 infection IgG+-based (late responders, R-; early responders, R+; pauci responders, PR). In all receipts, amplification of B cells and NK cells, including IL4-producing B cells and IL4-producing CD8+ T cells, is early stimulated by the vaccine. After the boost, we observed a growing increase of NK cells but a resistance of T cells, IFNγ-producing CD4+T cells, and IFNγ-producing NK cells. Also, hematologic parameters decline until the boost. The positive association of IFNγ-producing NK with IFNγ-producing CD4+T cells by the multiple mixed-effect model, adjusted for confounders (p = 0.036) as well as the correlation matrix (r = 0.6, p < 0.01), suggests a relationship between these two subsets of lymphocytes. Conclusions: These findings introduce several concerns about policy delay in vaccination: based on immunological protection, B cells and the persistent increase of NK cells during 2 doses of the mRNA-based vaccine could provide further immune protection against the virus, while CD8+ T cells increased slightly only in the R+ and PR groups.

Porcine Epidemic Diarrhea Virus Infection Disrupts the Nasal Endothelial Barrier To Favor Viral Dissemination.

Crossing the endothelium from the entry site and spreading in the bloodstream are crucial but obscure steps in the pathogenesis of many emerging viruses. Previous studies confirmed that porcine epidemic diarrhea virus (PEDV) caused intestinal infection by intranasal inoculation. However, the role of the nasal endothelial barrier in PEDV translocation remains unclear. Here, we demonstrated that PEDV infection causes nasal endothelial dysfunction to favor viral dissemination. Intranasal inoculation with PEDV compromised the integrity of endothelial cells (ECs) in nasal microvessels. The matrix metalloproteinase 7 (MMP-7) released from the PEDV-infected nasal epithelial cells (NECs) contributed to the destruction of endothelial integrity by degrading the tight junctions, rather than direct PEDV infection. Moreover, the proinflammatory cytokines released from PEDV-infected NECs activated ECs to upregulate ICAM-1 expression, which favored peripheral blood mononuclear cells (PBMCs) migration. PEDV could further exploit migrated cells to favor viral dissemination. Together, our results reveal the mechanism by which PEDV manipulates the endothelial dysfunction to favor viral dissemination and provide novel insights into how coronavirus interacts with the endothelium. IMPORTANCE The endothelial barrier is the last but vital defense against systemic viral transmission. Porcine epidemic diarrhea virus (PEDV) can cause severe atrophic enteritis and acute viremia. However, the mechanisms by which the virus crosses the endothelial barrier and causes viremia are poorly understood. In this study, we revealed the mechanisms of endothelial dysfunction in PEDV infection. The viral infection activates NECs and causes the upregulation of MMP-7 and proinflammatory cytokines. Using NECs, ECs, and PBMCs as in vitro models, we determined that the released MMP-7 contributed to the destruction of endothelial barrier, and the released proinflammatory cytokines activated ECs to facilitate PBMCs migration. Moreover, the virus further exploited the migrated cells to promote viral dissemination. Thus, our results provide new insights into the mechanisms underlying endothelial dysfunction induced by coronavirus infection.

Genetic ancestry effects on the response to viral infection are pervasive but cell type specific.

Humans differ in their susceptibility to infectious disease, partly owing to variation in the immune response after infection. We used single-cell RNA sequencing to quantify variation in the response to influenza infection in peripheral blood mononuclear cells from European- and African-ancestry males. Genetic ancestry effects are common but highly cell type specific. Higher levels of European ancestry are associated with increased type I interferon pathway activity in early infection, which predicts reduced viral titers at later time points. Substantial population-associated variation is explained by cis-expression quantitative trait loci that are differentiated by genetic ancestry. Furthermore, genetic ancestry­associated genes are enriched among genes correlated with COVID-19 disease severity, suggesting that the early immune response contributes to ancestry-associated differences for multiple viral infection outcomes.

Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques.

The speed of development, versatility and efficacy of mRNA-based vaccines have been amply demonstrated in the case of SARS-CoV-2. DNA vaccines represent an important alternative since they induce both humoral and cellular immune responses in animal models and in human trials. We tested the immunogenicity and protective efficacy of DNA-based vaccine regimens expressing different prefusion-stabilized Wuhan-Hu-1 SARS-CoV-2 Spike antigens upon intramuscular injection followed by electroporation in rhesus macaques. Different Spike DNA vaccine regimens induced antibodies that potently neutralized SARS-CoV-2 in vitro and elicited robust T cell responses. The antibodies recognized and potently neutralized a panel of different Spike variants including Alpha, Delta, Epsilon, Eta and A.23.1, but to a lesser extent Beta and Gamma. The DNA-only vaccine regimens were compared to a regimen that included co-immunization of Spike DNA and protein in the same anatomical site, the latter of which showed significant higher antibody responses. All vaccine regimens led to control of SARS-CoV-2 intranasal/intratracheal challenge and absence of virus dissemination to the lower respiratory tract. Vaccine-induced binding and neutralizing antibody titers and antibody-dependent cellular phagocytosis inversely correlated with transient virus levels in the nasal mucosa. Importantly, the Spike DNA+Protein co-immunization regimen induced the highest binding and neutralizing antibodies and showed the strongest control against SARS-CoV-2 challenge in rhesus macaques.

Cell specific peripheral immune responses predict survival in critical COVID-19 patients.

SARS-CoV-2 triggers a complex systemic immune response in circulating blood mononuclear cells. The relationship between immune cell activation of the peripheral compartment and survival in critical COVID-19 remains to be established. Here we use single-cell RNA sequencing and Cellular Indexing of Transcriptomes and Epitomes by sequence mapping to elucidate cell type specific transcriptional signatures that associate with and predict survival in critical COVID-19. Patients who survive infection display activation of antibody processing, early activation response, and cell cycle regulation pathways most prominent within B-, T-, and NK-cell subsets. We further leverage cell specific differential gene expression and machine learning to predict mortality using single cell transcriptomes. We identify interferon signaling and antigen presentation pathways within cDC2 cells, CD14 monocytes, and CD16 monocytes as predictors of mortality with 90% accuracy. Finally, we validate our findings in an independent transcriptomics dataset and provide a framework to elucidate mechanisms that promote survival in critically ill COVID-19 patients. Identifying prognostic indicators among critical COVID-19 patients holds tremendous value in risk stratification and clinical management.

Communication Pattern Changes Along With Declined IGF1 of Immune Cells in COVID-19 Patients During Disease Progression.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes the coronavirus disease 2019 (COVID-19) pandemic, represents a global crisis. Most patients developed mild/moderate symptoms, and the status of immune system varied in acute and regulatory stages. The crosstalk between immune cells and the dynamic changes of immune cell contact is rarely described. Here, we analyzed the features of immune response of paired peripheral blood mononuclear cell (PBMC) samples from the same patients during acute and regulatory stages. Consistent with previous reports, both myeloid and T cells turned less inflammatory and less activated at recovery phase. Additionally, the communication patterns of myeloid-T cell and T-B cell are obviously changed. The crosstalk analysis reveals that typical inflammatory cytokines and several chemokines are tightly correlated with the recovery of COVID-19. Intriguingly, the signal transduction of metabolic factor insulin-like growth factor 1 (IGF1) is altered at recovery phase. Furthermore, we confirmed that the serum levels of IGF1 and several inflammatory cytokines are apparently dampened after the negative conversion of SARS-CoV-2 RNA. Thus, these results reveal several potential detection and therapeutic targets that might be used for COVID-19 recovery.

Off-the-Shelf Partial HLA Matching SARS-CoV-2 Antigen Specific T Cell Therapy: A New Possibility for COVID-19 Treatment.

BACKGROUND: Immunological characteristics of COVID-19 show pathological hyperinflammation associated with lymphopenia and dysfunctional T cell responses. These features provide a rationale for restoring functional T cell immunity in COVID-19 patients by adoptive transfer of SARS-CoV-2 specific T cells. METHODS: To generate SARS-CoV-2 specific T cells, we isolated peripheral blood mononuclear cells from 7 COVID-19 recovered and 13 unexposed donors. Consequently, we stimulated cells with SARS-CoV-2 peptide mixtures covering spike, membrane and nucleocapsid proteins. Then, we culture expanded cells with IL-2 for 21 days. We assessed immunophenotypes, cytokine profiles, antigen specificity of the final cell products. RESULTS: Our results show that SARS-CoV-2 specific T cells could be expanded in both COVID-19 recovered and unexposed groups. Immunophenotypes were similar in both groups showing CD4+ T cell dominance, but CD8+ and CD3+CD56+ T cells were also present. Antigen specificity was determined by ELISPOT, intracellular cytokine assay, and cytotoxicity assays. One out of 14 individuals who were previously unexposed to SARS-CoV-2 failed to show antigen specificity. Moreover, ex-vivo expanded SARS-CoV-2 specific T cells mainly consisted of central and effector memory subsets with reduced alloreactivity against HLA-unmatched cells suggesting the possibility for the development of third-party partial HLA-matching products. DISCUSSION: In conclusion, our findings show that SARS-CoV-2 specific T cell can be readily expanded from both COVID-19 and unexposed individuals and can therefore be manufactured as a biopharmaceutical product to treat severe COVID-19 patients. ONE SENTENCE SUMMARY: Ex-vivo expanded SARS-CoV-2 antigen specific T cells developed as third-party partial HLA-matching products may be a promising approach for treating severe COVID-19 patients that do not respond to previous treatment options.

Cellular and humoral functional responses after BNT162b2 mRNA vaccination differ longitudinally between naive and subjects recovered from COVID-19.

We have analyzed BNT162b2 vaccine-induced immune responses in naive subjects and individuals recovered from coronavirus disease 2019 (COVID-19), both soon after (14 days) and later after (almost 8 months) vaccination. Plasma spike (S)-specific immunoglobulins peak after one vaccine shot in individuals recovered from COVID-19, while a second dose is needed in naive subjects, although the latter group shows reduced levels all along the analyzed period. Despite how the neutralization capacity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mirrors this behavior early after vaccination, both groups show comparable neutralizing antibodies and S-specific B cell levels late post-vaccination. When studying cellular responses, naive individuals exhibit higher SARS-CoV-2-specific cytokine production, CD4+ T cell activation, and proliferation than do individuals recovered from COVID-19, with patent inverse correlations between humoral and cellular variables early post-vaccination. However, almost 8 months post-vaccination, SARS-CoV-2-specific responses are comparable between both groups. Our data indicate that a previous history of COVID-19 differentially determines the functional T and B cell-mediated responses to BNT162b2 vaccination over time.

Time-Resolved Gene Expression Analysis Monitors the Regulation of Inflammatory Mediators and Attenuation of Adaptive Immune Response by Vitamin D.

Peripheral blood mononuclear cells (PBMCs) belong to the innate and adaptive immune system and are highly sensitive and responsive to changes in their systemic environment. In this study, we focused on the time course of transcriptional changes in freshly isolated human PBMCs 4, 8, 24 and 48 h after onset of stimulation with the active vitamin D metabolite 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). Taking all four time points together, 662 target genes were identified and segregated either by time of differential gene expression into 179 primary and 483 secondary targets or by driver of expression change into 293 direct and 369 indirect targets. The latter classification revealed that more than 50% of target genes were primarily driven by the cells' response to ex vivo exposure than by the nuclear hormone and largely explained its down-regulatory effect. Functional analysis indicated vitamin D's role in the suppression of the inflammatory and adaptive immune response by down-regulating ten major histocompatibility complex class II genes, five alarmins of the S100 calcium binding protein A family and by affecting six chemokines of the C-X-C motif ligand family. Taken together, studying time-resolved responses allows to better contextualize the effects of vitamin D on the immune system.

In Acute Dengue Infection, High TIM-3 Expression May Contribute to the Impairment of IFNγ Production by Circulating Vδ2 T Cells.

γδ T cells are innate cells able to quickly eliminate pathogens or infected/tumoral cells by their antiviral and adjuvancy activities. The role of γδ T cells during Dengue Viral Infection (DENV) infection is not fully elucidated. Nevertheless, human primary γδ T cells have been shown to kill in vitro DENV-infected cells, thus highlighting their possible antiviral function. The aim of this work was to characterize the phenotype and function of Vδ2 T cells in DENV patients. Fifteen DENV patients were enrolled for this study and peripheral blood mononuclear cells (PBMC) were used to analyze Vδ2-T-cell frequency, differentiation profile, activation/exhaustion status, and functionality by multiparametric flow cytometry. Our data demonstrated that DENV infection was able to significantly reduce Vδ2-T-cell frequency and to increase their activation (CD38 and HLA-DR) and exhaustion markers (PD-1 and TIM-3). Furthermore, Vδ2 T cells showed a reduced capability to produce IFN-γ after phosphoantigenic stimulation that can be associated to TIM-3 expression. Several studies are needed to depict the possible clinical impact of γδ-T-cell impairment on disease severity and to define the antiviral and immunoregulatory activities of γδ T cells in the first phases of infection.

HLA-A∗02:01 restricted T cell receptors against the highly conserved SARS-CoV-2 polymerase cross-react with human coronaviruses.

Cross-reactivity and direct killing of target cells remain underexplored for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-specific CD8+ T cells. Isolation of T cell receptors (TCRs) and overexpression in allogeneic cells allows for extensive T cell reactivity profiling. We identify SARS-CoV-2 RNA-dependent RNA polymerase (RdRp/NSP12) as highly conserved, likely due to its critical role in the virus life cycle. We perform single-cell TCRαß sequencing in human leukocyte antigen (HLA)-A∗02:01-restricted, RdRp-specific T cells from SARS-CoV-2-unexposed individuals. Human T cells expressing these TCRαß constructs kill target cell lines engineered to express full-length RdRp. Three TCR constructs recognize homologous epitopes from common cold coronaviruses, indicating CD8+ T cells can recognize evolutionarily diverse coronaviruses. Analysis of individual TCR clones may help define vaccine epitopes that can induce long-term immunity against SARS-CoV-2 and other coronaviruses.

Recruitment of highly cytotoxic CD8+ T cell receptors in mild SARS-CoV-2 infection.

T cell immunity is crucial for control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and has been studied widely on a quantitative level. However, the quality of responses, in particular of CD8+ T cells, has only been investigated marginally so far. Here, we isolate T cell receptor (TCR) repertoires specific for immunodominant SARS-CoV-2 epitopes restricted to common human Leukocyte antigen (HLA) class I molecules in convalescent individuals. SARS-CoV-2-specific CD8+ T cells are detected up to 12 months after infection. TCR repertoires are diverse, with heterogeneous functional avidity and cytotoxicity toward virus-infected cells, as demonstrated for TCR-engineered T cells. High TCR functionality correlates with gene signatures that, remarkably, could be retrieved for each epitope:HLA combination analyzed. Overall, our data demonstrate that polyclonal and highly functional CD8+ TCRs-classic features of protective immunity-are recruited upon mild SARS-CoV-2 infection, providing tools to assess the quality of and potentially restore functional CD8+ T cell immunity.

Sex differences in innate anti-viral immune responses to respiratory viruses and in their clinical outcomes in a birth cohort study.

The mechanisms explaining excess morbidity and mortality in respiratory infections among males are poorly understood. Innate immune responses are critical in protection against respiratory virus infections. We hypothesised that innate immune responses to respiratory viruses may be deficient in males. We stimulated peripheral blood mononuclear cells from 345 participants at age 16 years in a population-based birth cohort with three live respiratory viruses (rhinoviruses A16 and A1, and respiratory syncytial virus) and two viral mimics (R848 and CpG-A, to mimic responses to SARS-CoV-2) and investigated sex differences in interferon (IFN) responses. IFN-α responses to all viruses and stimuli were 1.34-2.06-fold lower in males than females (P = 0.018 - < 0.001). IFN-ß, IFN-γ and IFN-induced chemokines were also deficient in males across all stimuli/viruses. Healthcare records revealed 12.1% of males and 6.6% of females were hospitalized with respiratory infections in infancy (P = 0.017). In conclusion, impaired innate anti-viral immunity in males likely results in high male morbidity and mortality from respiratory virus infections.

Analysis of the humoral and cellular immune response after a full course of BNT162b2 anti-SARS-CoV-2 vaccine in cancer patients treated with PD-1/PD-L1 inhibitors with or without chemotherapy: an update after 6 months of follow-up.

BACKGROUND: The durability of immunogenicity of SARS-CoV-2 vaccination in cancer patients remains to be elucidated. We prospectively evaluated the immunogenicity of the vaccine in triggering both the humoral and the cell-mediated immune response in cancer patients treated with anti-programmed cell death protein 1/programmed death-ligand 1 with or without chemotherapy 6 months after BNT162b2 vaccine. PATIENTS AND METHODS: In the previous study, 88 patients were enrolled, whereas the analyses below refer to the 60 patients still on immunotherapy at the time of the follow-up. According to previous SARS-CoV-2 exposure, patients were classified as SARS-CoV-2-naive (without previous SARS-CoV-2 exposure) and SARS-CoV-2-experienced (with previous SARS-CoV-2 infection). Neutralizing antibody (NT Ab) titer against the B.1.1 strain and total anti-spike immunoglobulin G concentration were quantified in serum samples. The enzyme-linked immunosorbent spot assay was used for quantification of anti-spike interferon-γ (IFN-γ)-producing cells/106 peripheral blood mononuclear cells. Fifty patients (83.0%) were on immunotherapy alone, whereas 10 patients (7%) were on chemo-immunotherapy. We analyzed separately patients on immunotherapy and patients on chemo-immunotherapy. RESULTS: The median T-cell response at 6 months was significantly lower than that measured at 3 weeks after vaccination [50 interquartile range (IQR) 20-118.8 versus 175 IQR 67.5-371.3 IFN-γ-producing cells/106 peripheral blood mononuclear cells; P < 0.0001]. The median reduction of immunoglobulin G concentration was 88% in SARS-CoV-2-naive subjects and 2.1% in SARS-CoV-2-experienced subjects. SARS-CoV-2 NT Ab titer was maintained in SARS-CoV-2-experienced subjects, whereas a significant decrease was observed in SARS-CoV-2-naive subjects (from median 1 : 160, IQR 1 : 40-1 : 640 to median 1 : 20, IQR 1 : 10-1 : 40; P < 0.0001). A weak correlation was observed between SARS-CoV-2 NT Ab titer and spike-specific IFN-γ-producing cells at both 6 months and 3 weeks after vaccination (r = 0.467; P = 0.0002 and r = 0.428; P = 0.0006, respectively). CONCLUSIONS: Our work highlights a reduction in the immune response in cancer patients, particularly in SARS-CoV-2-naive subjects. Our data support administering a third dose of COVID-19 vaccine to cancer patients treated with programmed cell death protein 1/programmed death-ligand 1 inhibitors.

Sex-Related Differences in Innate and Adaptive Immune Responses to SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) exhibits a sex bias with males showing signs of more severe disease and hospitalizations compared with females. The mechanisms are not clear but differential immune responses, particularly the initial innate immune response, between sexes may be playing a role. The early innate immune responses to SARS-CoV-2 have not been studied because of the gap in timing between the patient becoming infected, showing symptoms, and getting the treatment. The primary objective of the present study was to compare the response of dendritic cells (DCs) and monocytes from males and females to SARS-CoV-2, 24 h after infection. To investigate this, peripheral blood mononuclear cells (PBMCs) from healthy young individuals were stimulated in vitro with the virus. Our results indicate that PBMCs from females upregulated the expression of HLA-DR and CD86 on pDCs and mDCs after stimulation with the virus, while the activation of these cells was not significant in males. Monocytes from females also displayed increased activation than males. In addition, females secreted significantly higher levels of IFN-α and IL-29 compared with males at 24 h. However, the situation was reversed at 1 week post stimulation and males displayed high levels of IFN-α production compared with females. Further investigations revealed that the secretion of CXCL-10, a chemokine associated with lung complications, was higher in males than females at 24 h. The PBMCs from females also displayed increased induction of CTLs. Altogether, our results suggest that decreased activation of pDCs, mDCs, and monocytes and the delayed and prolonged IFN-α secretion along with increased CXCL-10 secretion may be responsible for the increased morbidity and mortality of males to COVID-19.

Distinct immune signatures discriminate between asymptomatic and presymptomatic SARS-CoV-2pos subjects.

Increasing numbers of SARS-CoV-2-positive (SARS-CoV-2pos) subjects are detected at silent SARS-CoV-2 infection stage (SSIS). Yet, SSIS represents a poorly examined time-window wherein unknown immunity patterns may contribute to the fate determination towards persistently asymptomatic or overt disease. Here, we retrieved blood samples from 19 asymptomatic and 12 presymptomatic SARS-CoV-2pos subjects, 47 age/gender-matched patients with mild or moderate COVID-19 and 27 normal subjects, and interrogated them with combined assays of 44-plex CyTOF, RNA-seq and Olink. Notably, both asymptomatic and presymptomatic subjects exhibited numerous readily detectable immunological alterations, while certain parameters including more severely decreased frequencies of CD107alow classical monocytes, intermediate monocytes, non-classical monocytes and CD62Lhi CD8+ Tnaïve cells, reduced plasma STC1 level but an increased frequency of CD4+ NKT cells combined to distinguish the latter. Intercorrelation analyses revealed a particular presymptomatic immunotype mainly manifesting as monocytic overactivation and differentiation blockage, a likely lymphocyte exhaustion and immunosuppression, yielding mechanistic insights into SSIS fate determination, which could potentially improve SARS-CoV-2 management.

Multi-omic approach identifies a transcriptional network coupling innate immune response to proliferation in the blood of COVID-19 cancer patients.

Clinical outcomes of COVID-19 patients are worsened by the presence of co-morbidities, especially cancer leading to elevated mortality rates. SARS-CoV-2 infection is known to alter immune system homeostasis. Whether cancer patients developing COVID-19 present alterations of immune functions which might contribute to worse outcomes have so far been poorly investigated. We conducted a multi-omic analysis of immunological parameters in peripheral blood mononuclear cells (PBMCs) of COVID-19 patients with and without cancer. Healthy donors and SARS-CoV-2-negative cancer patients were also included as controls. At the infection peak, cytokine multiplex analysis of blood samples, cytometry by time of flight (CyTOF) cell population analyses, and Nanostring gene expression using Pancancer array on PBMCs were performed. We found that eight pro-inflammatory factors (IL-6, IL-8, IL-13, IL-1ra, MIP-1a, IP-10) out of 27 analyzed serum cytokines were modulated in COVID-19 patients irrespective of cancer status. Diverse subpopulations of T lymphocytes such as CD8+T, CD4+T central memory, Mucosal-associated invariant T (MAIT), natural killer (NK), and γδ T cells were reduced, while B plasmablasts were expanded in COVID-19 cancer patients. Our findings illustrate a repertoire of aberrant alterations of gene expression in circulating immune cells of COVID-19 cancer patients. A 19-gene expression signature of PBMCs is able to discriminate COVID-19 patients with and without solid cancers. Gene set enrichment analysis highlights an increased gene expression linked to Interferon α, γ, α/ß response and signaling which paired with aberrant cell cycle regulation in cancer patients. Ten out of the 19 genes, validated in a real-world consecutive cohort, were specific of COVID-19 cancer patients independently from different cancer types and stages of the diseases, and useful to stratify patients in a COVID-19 disease severity-manner. We also unveil a transcriptional network involving gene regulators of both inflammation response and proliferation in PBMCs of COVID-19 cancer patients.