Pediatric Respiratory Viral Infection.

Reflecting on this Special Issue dedicated to pediatric respiratory viruses, it is evident that the shadow cast by the global SARS-CoV-2 pandemic has profoundly impacted individuals of all ages and backgrounds, neonates and school-aged children being vulnerable cohorts resulting from the evolving immunological profiles and limited exposures to immunity-building experienced during this unprecedented era [...].

Prevalence of human respiratory pathogens and associated mucosal cytokine levels in young children and adults: a cross-sectional observational study in the Netherlands during the winter of 2012/2013.

Respiratory pathogens can cause severe disease and even death, especially in the very young and very old. Studies investigating their prevalence often focus on individuals presenting to healthcare providers with symptoms. However, the design of prevention strategies, e.g. which target groups to vaccinate, will benefit from knowledge on the prevalence of, risk factors for and host response to these pathogens in the general population. In this study, upper respiratory samples (n = 1311) were collected cross-sectionally during winter from 11- and 24-month old children, their parents, and adults ≥60 years of age that were recruited irrespective of seeking medical care. Almost all children, approximately two-thirds of parents and a quarter of older adults tested positive for at least one pathogen, often in the absence of symptoms. Viral interference was evident for the combination of rhinovirus and respiratory syncytial virus. Attending childcare facilities and having siblings associated with increased pathogen counts in children. On average, children showed increased levels of mucosal cytokines compared to parents and especially proinflammatory molecules associated with the presence of symptoms. These findings may guide further research into transmission patterns of respiratory pathogens and assist in determining the most appropriate strategies for the prediction and prevention of disease.

Effects of Obstructive Sleep Apnea on Airway Immunity and Susceptibility to Respiratory Infections.

Obstructive sleep apnea is a prevalent sleep disorder characterized by recurrent episodes of partial or complete upper airway collapse during sleep, leading to disrupted breathing patterns and intermittent hypoxia. OSA results in systemic inflammation but also directly affects the upper and lower airways leading to upregulation of inflammatory pathways and alterations of the local microbiome. These changes result in increased susceptibility to respiratory infections such as influenza, COVID-19, and bacterial pneumonia. This relationship is more complex and bidirectional in individuals with chronic lung disease such as chronic obstructive lung disease, interstitial lung disease and bronchiectasis.

Gut microbial features may influence antiviral IgG levels after vaccination against viral respiratory infectious diseases: the evidence from two-sample bidirectional mendelian randomization.

BACKGROUND: Vaccination is effective in preventing viral respiratory infectious diseases through protective antibodies and the gut microbiome has been proven to regulate human immunity. This study explores the causal correlations between gut microbial features and serum-specific antiviral immunoglobulin G (IgG) levels. METHODS: We conduct a two-sample bidirectional Mendelian randomization (MR) analysis using genome-wide association study (GWAS) summary data to explore the causal relationships between 412 gut microbial features and four antiviral IgG (for influenza A, measles, rubella, and mumps) levels. To make the results more reliable, we used four robust methods and performed comprehensive sensitivity analyses. RESULTS: The MR analyses revealed 26, 13, 20, and 18 causal associations of the gut microbial features influencing four IgG levels separately. ​Interestingly, ten microbial features, like genus Collinsella, species Bifidobacterium longum, and the biosynthesis of L-alanine have shown the capacity to regulate multiple IgG levels with consistent direction (rise or fall). The ​reverse MR analysis suggested several potential causal associations of IgG levels affecting microbial features. CONCLUSIONS: The human immune response against viral respiratory infectious diseases could be modulated by changing the abundance of gut microbes, which provided new approaches for the intervention of viral respiratory infections.

Cutting Edge: First Lung Infection Permanently Enlarges Lymph Nodes and Enhances New T Cell Responses.

Humans experience frequent respiratory infections. Immunology and vaccinology studies in mice are typically performed in naive specific pathogen-free animals responding to their very first respiratory challenge. We found that the first respiratory infection induces lifelong enlargement of the lung-draining mediastinal lymph nodes (medLNs). Furthermore, infection-experienced medLNs supported better naive T cell surveillance and effector responses to new unrelated infections that exhibited more biased accumulation and memory establishment within the lung. Moreover, we observed that weight loss induced by influenza infection was substantially reduced in mice that had recovered from a previous unrelated respiratory viral challenge. These data show that the lack of infectious history and corresponding medLN hypoplasia in specific pathogen-free mice alter their immune response to lung infections. Preclinical vaccination and immunology studies should consider the previous infectious experience of the model organism.

Intranasal neomycin evokes broad-spectrum antiviral immunity in the upper respiratory tract.

Respiratory virus infections in humans cause a broad-spectrum of diseases that result in substantial morbidity and mortality annually worldwide. To reduce the global burden of respiratory viral diseases, preventative and therapeutic interventions that are accessible and effective are urgently needed, especially in countries that are disproportionately affected. Repurposing generic medicine has the potential to bring new treatments for infectious diseases to patients efficiently and equitably. In this study, we found that intranasal delivery of neomycin, a generic aminoglycoside antibiotic, induces the expression of interferon-stimulated genes (ISGs) in the nasal mucosa that is independent of the commensal microbiota. Prophylactic or therapeutic administration of neomycin provided significant protection against upper respiratory infection and lethal disease in a mouse model of COVID-19. Furthermore, neomycin treatment protected Mx1 congenic mice from upper and lower respiratory infections with a highly virulent strain of influenza A virus. In Syrian hamsters, neomycin treatment potently mitigated contact transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In healthy humans, intranasal application of neomycin-containing Neosporin ointment was well tolerated and effective at inducing ISG expression in the nose in a subset of participants. These findings suggest that neomycin has the potential to be harnessed as a host-directed antiviral strategy for the prevention and treatment of respiratory viral infections.

The role of HPV11 E7 in modulating STING-dependent interferon ß response in recurrent respiratory papillomatosis.

Recurrent respiratory papillomatosis (RRP) is a rare benign tumor caused mainly by the infection of the respiratory tract epithelial cells by the human papillomavirus (HPV) type 6/11. However, the specific mechanisms underlying the inhibition of the host's innate immune response by HPV remain unclear. For this purpose, we employed single-cell RNA sequencing to analyze the states of various immune cells in RRP samples post-HPV infection and utilized a cellular model of HPV infection to elucidate the mechanisms by which HPV evades the innate immune system in RRP. The results revealed distinct immune cell heterogeneity in RRP and demonstrated that HPV11 E7 can inhibit the phosphorylation of the stimulator of interferon genes protein, thereby circumventing the body's antiviral response. In vitro co-culture experiments demonstrated that stimulation of macrophages to produce interferon-beta induced the death of HPV-infected epithelial cells, also reducing HPV viral levels. In summary, our study preliminarily identifies the potential mechanisms by which HPV evades the host's antiviral immune response, as well as the latent antiviral functions exhibited by activated macrophages. This research serves as an initial exploration of antiviral immune evasion in RRP, laying a solid foundation for investigating immunotherapeutic approaches for the disease.IMPORTANCESurgical tumor reduction is the most common treatment for recurrent respiratory papillomatosis (RRP). One of the characteristics of RRP is its persistent recurrence, and multiple surgeries are usually required to control the symptoms. Recently, some adjuvant therapies have shown effectiveness, but none of them can completely clear human papillomavirus (HPV) infection, and thus, a localized antiviral immune response is significant for disease control; after all, HPV infection is limited to the epithelium. Inhibition of interferon-beta (IFN-ß) secretion by HPV11 E7 viral proteins in epithelial cells by affecting stimulator of interferon genes phosphorylation may account for the persistence of low-risk HPV replication in the RRP. Moreover, suppression of the IFN-I pathway in RRP cell types might provide clues regarding the hyporeactive function of local immune cells. However, activation of macrophage groups to produce IFN-ß can still destroy HPV-infected cells.

Determinants of radiological patterns and severity in immunocompromised adults with Metapneumovirus infection.

BACKGROUND: Human Metapneumovirus (HMPV) belongs to the Pneumoviridae family and is responsible for respiratory infections. Mild infections are well-recognized in children, while its precise impact in various categories of immunocompromised adults has not been well addressed. RESEARCH QUESTION: We retrospectively studied HMPV infections in immunocompromised adults followed in two large French university medical centers. STUDY DESIGN AND METHODS: We identified immunocompromised adults with positive HMPV Polymerase Chain Reaction (PCR) for 36 months and reviewed their medical charts. For lung transplant recipients (LTR), FEV1 was collected at baseline, during and after infection. Imaging was centralized and chest involvement was categorized by dominant CT patterns. We compared severe patients (requiring oxygen or ventilation) and non hypoxemic patients. RESULTS: Seventy-two patients were included, 27 were LTR, 25 had a hematological malignancy or were hematopoietic stem cell recipients, 20 had another immunocompromised status. Twenty patients (28%) presented a hypoxemic infection, requiring hospitalization and intensive care units transfers in 50/72 (69.4%) and 9/72 (12.5%) respectively, with only one death. Hypoxemia was less pronounced in LTRs (p = 0.014). Finally, age and dyspnea remained independent factors associated with hypoxemia (p < 0.005). The most frequent radiological patterns were bronchopneumonia (34.2%) and bronchiolitis (39.5% and 64.3% in the overall population and in LTRs respectively, p = 0.045). FEV1 improved in LTRs at one month and 85% had recovered their baseline FEV1 within 6 months. INTERPRETATIONS: In immunocompromised adults, HMPV infections required frequent hospitalizations and ICU transfers, while mortality is low. In LTRs, bronchiolitis pattern was predominant with short and long-term favorable outcome.

Profiling of VEGF Receptors and Immune Checkpoints in Recurrent Respiratory Papillomatosis.

OBJECTIVES: Recurrent respiratory papillomatosis (RRP) is caused by human papilloma virus (HPV) infection of the aerodigestive tract that significantly impacts quality-of-life including the ability to communicate and breathe. Treatment was traditionally limited to serial ablative procedures in the O.R. with possible local adjuvant therapy, but new systemic therapies, such as Vascular endothelial growth factor (VEGF) inhibitors, are showing significant promise. This study aims to determine whether rationale exists for combination therapeutic approaches using VEGF inhibitors and/or immune checkpoint blockade. METHODS: Using fresh specimens from the O.R., we performed flow cytometry on papilloma, normal adjacent tissue, and blood. Papilloma and surrounding tissue were examined for expression of PD-L1, PD-L2, Galectin-9, VEGFR2, and VEGFR3. CD8+ and CD4+ T cells were assayed for expression of PD-1, TIGIT, LAG3, and TIM3. RESULTS: Our data shows that papilloma tissue exhibits significantly higher levels of PD-L1 and PD-L2 compared to adjacent tissue. Elevated levels of the VEGF receptor VEGFR3 were also observed in papilloma tissue. When examining T cells within the papilloma, elevated PD-1 and TIGIT expression was observed on CD8+ T cells, while levels of PD-1, TIGIT, and TIM3 were elevated on CD4+ T cells compared to PBMCs. Heterogenous marker expression was observed between individuals. CONCLUSIONS: Our analysis shows that RRP tissue shows elevated levels of multiple immune check point targets and VEGFR3, with varied patterns unique to each papilloma patient. Some of these immune checkpoint markers already have novel immunotherapies available or in development, providing molecular rationale to offer these systemic treatments to selected patients affected by RRP alongside VEGF inhibitors. Laryngoscope, 134:2819-2825, 2024.

Diagnosis of invasive respiratory mycoses in the immunocompromised host.

PURPOSE OF REVIEW: The burden of invasive fungal infection is increasing worldwide, largely due to a growing population at-risk. Most serious human fungal pathogens enter the host via the respiratory tract. Early identification and treatment of invasive fungal respiratory infections (IFRIs) in the immunocompromised host saves lives. However, their accurate diagnosis is a difficult challenge for clinicians and mortality remains high. RECENT FINDINGS: This article reviews IFRIs, focussing on host susceptibility factors, clinical presentation, and mycological diagnosis. Several new diagnostic tools are coming of age including molecular diagnostics and point-of-care antigen tests. As diagnosis of IFRI relies heavily on invasive procedures like bronchoalveolar lavage and lung biopsy, several novel noninvasive diagnostic techniques are in development, such as metagenomics, 'volatilomics' and advanced imaging technologies. SUMMARY: Where IFRI cannot be proven, clinicians must employ a 'weights-of-evidence' approach to evaluate host factors, clinical and mycological data. Implementation studies are needed to understand how new diagnostic tools can be best applied within clinical pathways. Differentiating invasive infection from colonization and identifying antifungal resistance remain key challenges. As our diagnostic arsenal expands, centralized clinical mycology laboratories and efforts to ensure access to new diagnostics in low-resource settings will become increasingly important.

Efficacy and Safety of an Ad26.RSV.preF-RSV preF Protein Vaccine in Older Adults.

BACKGROUND: Respiratory syncytial virus (RSV) can cause serious lower respiratory tract disease in older adults, but no licensed RSV vaccine currently exists. An adenovirus serotype 26 RSV vector encoding a prefusion F (preF) protein (Ad26.RSV.preF) in combination with RSV preF protein was previously shown to elicit humoral and cellular immunogenicity. METHODS: We conducted a randomized, double-blind, placebo-controlled, phase 2b, proof-of-concept trial to evaluate the efficacy, immunogenicity, and safety of an Ad26.RSV.preF-RSV preF protein vaccine. Adults who were 65 years of age or older were randomly assigned in a 1:1 ratio to receive vaccine or placebo. The primary end point was the first occurrence of RSV-mediated lower respiratory tract disease that met one of three case definitions: three or more symptoms of lower respiratory tract infection (definition 1), two or more symptoms of lower respiratory tract infection (definition 2), and either two or more symptoms of lower respiratory tract infection or one or more symptoms of lower respiratory tract infection plus at least one systemic symptom (definition 3). RESULTS: Overall, 5782 participants were enrolled and received an injection. RSV-mediated lower respiratory tract disease meeting case definitions 1, 2, and 3 occurred in 6, 10, and 13 vaccine recipients and in 30, 40, and 43 placebo recipients, respectively. Vaccine efficacy was 80.0% (94.2% confidence interval [CI], 52.2 to 92.9), 75.0% (94.2% CI, 50.1 to 88.5), and 69.8% (94.2% CI, 43.7 to 84.7) for case definitions 1, 2, and 3, respectively. After vaccination, RSV A2 neutralizing antibody titers increased by a factor of 12.1 from baseline to day 15, a finding consistent with other immunogenicity measures. Percentages of participants with solicited local and systemic adverse events were higher in the vaccine group than in the placebo group (local, 37.9% vs. 8.4%; systemic, 41.4% vs. 16.4%); most adverse events were mild to moderate in severity. The frequency of serious adverse events was similar in the vaccine group and the placebo group (4.6% and 4.7%, respectively). CONCLUSIONS: In adults 65 years of age or older, Ad26.RSV.preF-RSV preF protein vaccine was immunogenic and prevented RSV-mediated lower respiratory tract disease. (Funded by Janssen Vaccines and Prevention; CYPRESS ClinicalTrials.gov number, NCT03982199.).

Restricted Recruitment of NK Cells with Impaired Function Is Caused by HPV-Driven Immunosuppressive Microenvironment of Papillomas in Aggressive Juvenile-Onset Recurrent Respiratory Papillomatosis Patients.

Laryngopharynx epithelium neoplasia induced by HPV6/11 infection in juvenile-onset recurrent respiratory papillomatosis (JO-RRP) causes a great health issue characteristic of frequent relapse and aggressive disease progression. Local cell-mediated immunity shaped by the recruitment and activation of cytotoxic effector cells is critical for viral clearance. In this study, we found that NK cells in the papillomas of aggressive JO-RRP patients, in contrast to massive infiltrated T cells, were scarce in number and impaired in activation and cytotoxicity as they were in peripheral blood. Data from cell infiltration analysis indicated that the migration of NK cell to papilloma was restricted in aggressive JO-RRP patients. Further study showed that the skewed chemokine expression in the papillomas and elevated ICAM-1 expression in hyperplastic epithelia cells favored the T cell but not NK cell recruitment in aggressive JO-RRP patients. In parallel to the increased CD3+ T cells, we observed a dramatical increase in Tregs and Treg-promoting cytokines such as IL-4, IL-10 and TGFß in papillomas of aggressive JO-RRP patients. Our study suggested that likely initialized by the intrinsic change in neoplastic epithelial cells with persistent HPV infection, the aggressive papillomas built an entry barrier for NK cell infiltration and formed an immunosuppressive clump to fend off the immune attack from intra-papillomas NK cells. IMPORTANCE Frequent relapse and aggressive disease progression of juvenile-onset recurrent respiratory papillomatosis (JO-RRP) pose a great challenge to the complete remission of HPV 6/11 related laryngeal neoplasia. Local immune responses in papillomas are more relevant to the disease control considering the locale infected restriction of HPV virus in epitheliums. In our study, the restricted NK cell number and reduced expression of activating NKp30 receptor suggested one possible mechanism underlying impaired NK cell defense ability in aggressive JO-RRP papillomas. Meanwhile, the negative impact of HPV persistent infection on NK cell number and function represented yet another example of a chronic pathogen subverting NK cell behavior, affirming a potentially important role for NK cells in viral containment. Further, the skewed chemokine/cytokine expression in the papillomas and the elevated adhesion molecules expression in hyperplastic epithelia cells provided important clues for understanding blocked infiltration and antiviral dysfunction of NK cells in papilloma.

Immune determinants of chronic sequelae after respiratory viral infection.

The acute effects of various respiratory viral infections have been well studied, with extensive characterization of the clinical presentation as well as viral pathogenesis and host responses. However, over the course of the recent COVID-19 pandemic, the incidence and prevalence of chronic sequelae after acute viral infections have become increasingly appreciated as a serious health concern. Post-acute sequelae of COVID-19, alternatively described as "long COVID-19," are characterized by symptoms that persist for longer than 28 days after recovery from acute illness. Although there exists substantial heterogeneity in the nature of the observed sequelae, this phenomenon has also been observed in the context of other respiratory viral infections including influenza virus, respiratory syncytial virus, rhinovirus, severe acute respiratory syndrome coronavirus, and Middle Eastern respiratory syndrome coronavirus. In this Review, we discuss the various sequelae observed following important human respiratory viral pathogens and our current understanding of the immunological mechanisms underlying the failure of restoration of homeostasis in the lung.

Assessment of a cellular host response test to risk-stratify suspected COVID-19 patients in the Emergency Department setting.

OBJECTIVE: Assess the IntelliSep Index (ISI) for risk stratification of patients presenting to the Emergency Department (ED) with respiratory symptoms suspected of COVID-19 during the pandemic. METHODS: An observational single-center study of prospective cohort of patients presenting to the ED during the early COVID-19 pandemic with respiratory symptoms and a CBC drawn within 4.5 hours of initial vital signs. A sample of this blood was aliquoted for performance of the ISI, and patients were followed for clinical outcomes. The study required no patient-centered activity beyond standard of care and treating clinicians were unaware of study enrollment and ISI test results. MAIN FINDINGS: 282 patients were included. The ISI ranges 0.1 to 10.0, with three interpretation bands indicating risk of adverse outcome: low (green), 0.1-4.9; intermediate (yellow), 5.0-6.2; and high (red), 6.3-10.0. Of 193 (68.4%) tested for SARS-CoV-2, 96 (49.7%) were positive. The ISI resulted in 182 (64.5%) green, 54 (18.1%) yellow, and 46 (15.6%) red band patients. Green band patients had a 1.1% (n = 2) 3-day mortality, while yellow and red band had 3.7% (n = 2, p > .05) and 10.9% (n = 5, p < .05) 3-day mortalities, respectively. Fewer green band patients required admission (96 [52.7%]) vs yellow (44 [81.5%]) and red (43 [93.5%]). Green band patients had more hospital free days (median 23 (Q1-Q3 20-25) than yellow (median 22 [Q1-Q3 0-23], p < 0.05) and red (median 21 [Q1-Q3 0-24], p < 0.01). SOFA increased with interpretation band: green (2, [Q1-Q3 0-4]) vs yellow (4, [Q1-Q3 2-5], p < 0.001) and red (5, [Q1-Q3 3-6]) p < 0.001). CONCLUSIONS: The ISI rapidly risk-stratifies patients presenting to the ED during the early COVID-19 pandemic with signs or suspicion of respiratory infection.

Differential Effects of Toll-Like Receptor Signaling on the Activation of Immune Responses in the Upper Respiratory Tract.

Vaccination through the upper respiratory tract (URT) is highly effective for the prevention of respiratory infectious diseases. Toll-like receptor (TLR)-based adjuvants are immunostimulatory and considered potential adjuvant candidates. However, the patterns of immune response to different TLRs at the URT have not been revealed. In this study, SPF mice were preexposed to TLR agonists intranasally to simulate the status of humans. Inflammatory response to TLR agonists and TLR signal-mediated adaptive immune responses were analyzed. The results revealed that similar to human tonsils, inflammatory response to stimulation with TLR4 or TLR2 agonist was attenuated in agonist-exposed mice but not in mice without this exposure. In contrast, TLR9 or TLR3 agonist preexposure did not affect the inflammatory response to restimulation by matching agonists. For the adaptive immune response, after agonist preexposure the antibody response to antigens adjuvanted with TLR4 or TLR2 agonist was substantially restricted, whereas, both antibody and T cell responses to antigens adjuvanted with TLR9 or TLR3 agonist were activated as robustly as in mice without agonist exposure. Moreover, we demonstrate that the mechanisms underlying the differential activation of TLRs are regulated at the level of TLR expression in innate and adaptive immune cells. These results indicate that TLRs on the cell surface (TLR4 and 2) and in the endolysosomal compartments (TLR9 and 3) display distinct immune response patterns. The findings provide important information for the use of TLR agonists as mucosal adjuvants and enhance our understanding of immune responses to bacterial and viral infections in the respiratory mucosa. IMPORTANCE Agonists of TLRs are potential adjuvant candidates for mucosal vaccination. We demonstrated that the TLR-mediated inflammatory and antibody responses in the URT of SPF mice exposed to extracellular TLR agonists were substantially restricted. In contrast, inflammatory and adaptive immune responses, including B and T cell activation, were not desensitized in mice exposed to intracellular TLR agonists. The distinct responsive patterns of extra and intracellular TLRs regulated at TLR expression in immune cells. The results indicated that TLRs differentially impact the innate and adaptive immune response in the URT, which contributes to the selection of TLR-based mucosal adjuvants and helps understand the difference between the immune response in bacterial and viral infections.

Early-life viral infections are associated with disadvantageous immune and microbiota profiles and recurrent respiratory infections.

The respiratory tract is populated by a specialized microbial ecosystem, which is seeded during and directly following birth. Perturbed development of the respiratory microbial community in early-life has been associated with higher susceptibility to respiratory tract infections (RTIs). Given a consistent gap in time between first signs of aberrant microbial maturation and the observation of the first RTIs, we hypothesized that early-life host-microbe cross-talk plays a role in this process. We therefore investigated viral presence, gene expression profiles and nasopharyngeal microbiota from birth until 12 months of age in 114 healthy infants. We show that the strongest dynamics in gene expression profiles occurred within the first days of life, mostly involving Toll-like receptor (TLR) and inflammasome signalling. These gene expression dynamics coincided with rapid microbial niche differentiation. Early asymptomatic viral infection co-occurred with stronger interferon activity, which was related to specific microbiota dynamics following, including early enrichment of Moraxella and Haemophilus spp. These microbial trajectories were in turn related to a higher number of subsequent (viral) RTIs over the first year of life. Using a multi-omic approach, we found evidence for species-specific host-microbe interactions related to consecutive susceptibility to RTIs. Although further work will be needed to confirm causality of our findings, together these data indicate that early-life viral encounters could impact subsequent host-microbe cross-talk, which is linked to later-life infections.

Integrated analysis of circulating immune cellular and soluble mediators reveals specific COVID19 signatures at hospital admission with utility for prediction of clinical outcomes.

Coronavirus disease 2019 (COVID19), caused by SARS-CoV-2, is a complex disease, with a variety of clinical manifestations ranging from asymptomatic infection or mild cold-like symptoms to more severe cases requiring hospitalization and critical care. The most severe presentations seem to be related with a delayed, deregulated immune response leading to exacerbated inflammation and organ damage with close similarities to sepsis. Methods: In order to improve the understanding on the relation between host immune response and disease course, we have studied the differences in the cellular (monocytes, CD8+ T and NK cells) and soluble (cytokines, chemokines and immunoregulatory ligands) immune response in blood between Healthy Donors (HD), COVID19 and a group of patients with non-COVID19 respiratory tract infections (NON-COV-RTI). In addition, the immune response profile has been analyzed in COVID19 patients according to disease severity. Results: In comparison to HDs and patients with NON-COV-RTI, COVID19 patients show a heterogeneous immune response with the presence of both activated and exhausted CD8+ T and NK cells characterised by the expression of the immune checkpoint LAG3 and the presence of the adaptive NK cell subset. An increased frequency of adaptive NK cells and a reduction of NK cells expressing the activating receptors NKp30 and NKp46 correlated with disease severity. Although both activated and exhausted NK cells expressing LAG3 were increased in moderate/severe cases, unsupervised cell clustering analyses revealed a more complex scenario with single NK cells expressing more than one immune checkpoint (PD1, TIM3 and/or LAG3). A general increased level of inflammatory cytokines and chemokines was found in COVID19 patients, some of which like IL18, IL1RA, IL36B and IL31, IL2, IFNα and TNFα, CXCL10, CCL2 and CCL8 were able to differentiate between COVID19 and NON-COV-RTI and correlated with bad prognosis (IL2, TNFα, IL1RA, CCL2, CXCL10 and CXCL9). Notably, we found that soluble NKG2D ligands from the MIC and ULBPs families were increased in COVID19 compared to NON-COV-RTI and correlated with disease severity. Conclusions: Our results provide a detailed comprehensive analysis of the presence of activated and exhausted CD8+T, NK and monocyte cell subsets as well as extracellular inflammatory factors beyond cytokines/chemokines, specifically associated to COVID19. Importantly, multivariate analysis including clinical, demographical and immunological experimental variables have allowed us to reveal specific immune signatures to i) differentiate COVID19 from other infections and ii) predict disease severity and the risk of death.