Surfactant therapy using vibrating-mesh nebulizers in adults with COVID-19-induced ARDS: A case series.

Coronavirus adult respiratory distress syndrome, characterized by decreased surfactant due to lysis of type II pneumocytes and hyaline membrane formation, contributes to severe hypoxemia. The administration of surfactant via high-flow nasal cannula (HFNC) may positively affect lung structure and function in this context. In this study, we report on five clinical cases, encompassing patients aged 40-60 years of both sexes, who tested positive for coronavirus disease 2019 via real-time polymerase chain reaction and exhibited significant pulmonary compromise with elevated inflammatory biomarkers. These patients were treated with aerosol therapy using surfactant delivered through vibrating-mesh nebulizers alongside HFNC. Of these patients, four demonstrated positive responses to the treatment, suggesting that aerosol therapy with surfactant through vibrating-mesh nebulizers could be a viable rescue therapy in adults receiving HFNC oxygen therapy for hypoxemic respiratory failure caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Unfortunately, one patient had a negative outcome and succumbed. The findings from these cases indicate that the use of aerosol therapy with vibrating-mesh nebulizers as rescue therapy might offer an alternative approach for managing adults with hypoxemic respiratory failure due to SARS-CoV-2, as evidenced by the positive outcomes in four out of the five cases presented.

The tumor microenvironment of benign and malignant salivary gland tumors.

BACKGROUND: Treatment of salivary gland tumors (SGTs) remains challenging. Little is known about the immune landscape of SGTs. We aimed to characterize the tumor microenvironment in benign and malignant SGTs. METHODS: Eleven benign and nine malignant tumors were collected from patients undergoing curative intent surgery. Specimens were analyzed using mass cytometry by time-of-flight. Immune cell populations were manually gated, and T cells were clustered using the FlowSOM algorithm. Population frequencies were compared between high-grade and low-grade malignancies, corrected for multiple hypothesis testing. RESULTS: There were trends towards increased CD4+ and CD8+ T cells among malignant tumors. High-grade malignancies exhibited trends towards higher frequencies of CD8+ PD-1+ CD39+ CD103+ exhausted T cells, CD4+ FoxP3+ TCF-1+ CD127- Tregs, and CD69+ CD25- CD4+ T cells compared to low-grade malignancies. CONCLUSION: SGTs exhibit significant immunologic diversity. High-grade malignancies tended to have greater infiltration of exhausted CD8+ T cells and Tregs, which may guide future studies for immunotherapy strategies.

A mass cytometry approach to track the evolution of T cell responses during infection and immunotherapy by paired T cell receptor repertoire and T cell differentiation state analysis.

T cell receptor (TCR) recognition followed by clonal expansion is a fundamental feature of adaptive immune responses. Here, we developed a mass cytometric (CyTOF) approach combining antibodies specific for different TCR Vα- and Vß-chains with antibodies against T cell activation and differentiation proteins to identify antigen-specific expansions of T cell subsets and assess aspects of cellular function. This strategy allowed for the identification of expansions of specific Vß and Vα chain expressing CD8+ and CD4+ T cells with varying differentiation states in response to Listeria monocytogenes, tumors, and respiratory influenza infection. Expanded Vß chain expressing T cells could be directly linked to the recognition of specific antigens from Listeria, tumor cells, or influenza. In the setting of influenza infection, we showed that the common therapeutic approaches of intramuscular vaccination or convalescent serum transfer altered the clonal diversity and differentiation state of responding T cells. Thus, we present a new method to monitor broad changes in TCR specificity paired with T cell differentiation during adaptive immune responses.

Síndrome de Asia: revisión sistemática de literatura

Ha habido muchos casos de aparición de autoanticuerpos y síntomas de enfermedad después de la exposición a adyuvantes, no solo después del aumento de senos con implantes de silicona, sino también como un efecto secundario muy raro de la vacunación, como el síndrome de la guerra del Golfo o el síndrome de miofascitis macrofágica. Las enfermedades cuyos síntomas se desarrollaron después de dicha exposición adyuvante se denominan síndrome autoinmune/inflamatorio inducido por adyuvantes (ASIA). El grupo de adyuvantes incluye no solo implantes de silicona, sílice, escualeno y aluminio, sino también componentes de tinta utilizados para hacer tatuajes. Analizando los informes disponibles sobre la influencia de los adyuvantes en el desarrollo de enfermedades autoinmunes, se concluye que, además de la exposición prolongada a la silicona, también es necesaria la coexistencia de otros factores, como genéticos o ambientales. Los análisis claramente no confirman un mayor riesgo de desarrollar una enfermedad autoinmune después del aumento de senos con implantes de silicona o tatuajes, pero parece que entre estas pacientes hay un grupo que está más predestinado a desarrollar síntomas de la enfermedad. En la población general, los beneficios de la vacunación son obvios, y el riesgo de eventos adversos graves después de la inmunización es incomparablemente menor que el riesgo de desarrollar una enfermedad específica y sus complicaciones, también para pacientes con enfermedades autoinmunes diagnosticadas. Debido a la heterogeneidad de los datos en estudios previos y las dificultades para diagnosticar ASIA, parece necesario realizar más análisis de la influencia de los adyuvantes en el desarrollo de enfermedades autoinmunes y refinar los criterios de diagnóstico de ASIA, que ahora permiten un diagnóstico demasiado fácil de esta enfermedad. (provisto por Infomedic International)

There have been many cases of occurrence of autoantibodies and disease symptoms after adjuvant exposure, not only after breast augmentation with silicone implants, but also as a very rare side effect of vaccination, such as Gulf War syndrome or macrophagic myofasciitis syndrome. Diseases whose symptoms developed after such adjuvant exposure are called adjuvant-induced autoimmune/inflammatory syndrome (ASIA). The adjuvant group includes not only silicone, silica, squalene and aluminum implants, but also ink components used to make tattoos. Analyzing the available reports on the influence of adjuvants on the development of autoimmune diseases, it is concluded that, in addition to prolonged exposure to silicone, the coexistence of other factors, such as genetic or environmental, is also necessary. The analyses clearly do not confirm an increased risk of developing an autoimmune disease after breast augmentation with silicone implants or tattoos, but it seems that among these patients there is a group that is more predestined to develop symptoms of the disease. In the general population, the benefits of vaccination are obvious, and the risk of serious adverse events after immunization is incomparably lower than the risk of developing a specific disease and its complications, also for patients with diagnosed autoimmune diseases. Due to the heterogeneity of data in previous studies and the difficulties in diagnosing ASIA, further analysis of the influence of adjuvants on the development of autoimmune diseases and refinement of the diagnostic criteria for ASIA, which now allow too easy diagnosis of this disease, seems necessary. (provided by Infomedic International)

Dynamic CD8+ T cell responses to cancer immunotherapy in human regional lymph nodes are disrupted in metastatic lymph nodes.

CD8+ T cell responses are critical for anti-tumor immunity. While extensively profiled in the tumor microenvironment, recent studies in mice identified responses in lymph nodes (LNs) as essential; however, the role of LNs in human cancer patients remains unknown. We examined CD8+ T cells in human head and neck squamous cell carcinomas, regional LNs, and blood using mass cytometry, single-cell genomics, and multiplexed ion beam imaging. We identified progenitor exhausted CD8+ T cells (Tpex) that were abundant in uninvolved LN and clonally related to terminally exhausted cells in the tumor. After anti-PD-L1 immunotherapy, Tpex in uninvolved LNs reduced in frequency but localized near dendritic cells and proliferating intermediate-exhausted CD8+ T cells (Tex-int), consistent with activation and differentiation. LN responses coincided with increased circulating Tex-int. In metastatic LNs, these response hallmarks were impaired, with immunosuppressive cellular niches. Our results identify important roles for LNs in anti-tumor immune responses in humans.

An Unusual Case of Severe Pneumonia Caused Due Candida Tropicalis With a Favorable Clinical Response to Antifungals in a Nonimmunocompromised Patient From the Community.

Severe pneumonia due to Candida tropicalis infection mainly occurs in immunosuppressed patients or those currently receiving broad-spectrum antibiotics. Herein, we report a case of severe pneumonia caused due to C tropicalis in an elderly patient. A 72-year-old man with a previous history of hypertension, ischemic stroke, and facial paralysis sequelae treated with the botulinic toxin, was admitted to the hospital for dyspnea. Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infection was negative. Computed tomography of the chest revealed bilateral consolidation with left predominance. A bronchoalveolar lavage sample was sent to molecular biology, but no microorganisms were detected using a FilmArray respiratory panel. However, mamanocandidas test for candida was 166 pg/mL (positive), and fungal structures were identified by the MALDI-TOF Biotyper mass spectrometry and attributed to C tropicalis. Antifungal therapy was started using caspofungin 75 mg as the initial dose followed by 50 mg daily. After 10 days of treatment, ventilatory weaning was achieved. By day 14, the patient was decannulated from the tracheostomy. Oral antifungal treatment with voriconazole was continued, and he was discharged from intensive care in good clinical condition. Severe pneumonia due to C tropicalis might occur in specific cases, especially in those patients with risk factors, and must thus be considered when approaching such cases.

Use of threshold PEP with an adult non-rebreather oxygen mask plus prone positioning in acute hypoxemic respiratory failure due to SARS-CoV-2 infection during the collapse of the health system in a low-income country.

During the coronavirus disease 2019 pandemic, Ecuador reported a collapse of the healthcare system, in which intensive care unit beds were lacking. Therefore, we sought to determine whether the use of threshold expiratory positive pressure with an adult non-rebreather oxygen mask plus prone positioning is useful for improving oxygenation. Twelve patients were included. Eight patients (66.7%) survived, while four patients (33.3%) died. Baseline arterial oxygen saturation (%) prior placement median (interquartile range) 85.5% (80%-89%) and arterial oxygen saturation (%) post placement of the device was median (interquartile range) (93%-96%) (P = 0.0001). Respiratory rate before placement was median (interquartile range) 38 (36-42) and post placement of the device was median (interquartile range) 24 (22-30) (P = 0.0005). The use of an adapted device might be useful for the management of acute hypoxemic respiratory failure due to severe acute respiratory syndrome coronavirus 2 pneumonia, particularly when mechanical ventilators and high-flow oxygen systems are unavailable.

The Effect of Participatory Heat Education on Agricultural Worker Knowledge.

OBJECTIVES: Farmworkers disproportionately experience preventable adverse health effects from heat exposure. We sought to evaluate the effect of participatory heat education on farmworker knowledge. METHODS: We conducted a parallel, comparison group intervention study to investigate the effectiveness of a Spanish/English participatory, culturally-tailored, heat education-based intervention on farmworker heat knowledge in the Summer 2019. We used convenience sampling to recruit adult outdoor farmworkers from Central/Eastern Washington State, USA. Crews were randomized to receive the intervention (n = 40 participants) versus not receive the intervention (n = 43 participants). We assessed changes in heat knowledge, scored on a scale from 0 to 11, between baseline, immediate post-intervention, and post-season, which was approximately three months after baseline, using the Wilcoxon signed-rank test. We compared differences in knowledge scores from baseline to post-season between groups using analysis of variance. RESULTS: Average knowledge scores improved from 4.6 (standard deviation [sd] 1.5) to 6.3 (sd 2.0) pre to post season in the intervention group (p < 0.001). There was a greater improvement in pre-post knowledge scores in the intervention (average difference 1.6, sd 2.0) versus the comparison group (average difference 0.41, sd 1.7) (p = 0.04). CONCLUSIONS: Participatory heat training was effective in improving farmworker heat knowledge over the course of a summer season. Results of this study will be used to guide heat prevention efforts for farmworkers. TRIAL REGISTRATION: ClinicalTrials.gov Registration Number: NCT04234802.

Impacto del lugar de residencia en la supervivencia de los pacientes con trasplante renal. ¿Puede la telemedicina mejorar este desenlace? / How residence affects the survival of kidney transplant recipients, can it be improved by telemedicine?

Antecedente: el trasplante renal es el tratamiento de elección en la enfermedad crónica terminal. Un adecuado seguimiento en el postrasplante mejora la supervivencia del injerto y del paciente a largo plazo. Objetivo: comparar los desenlaces clínicos de la población trasplantada renal que vive en el área metropolitana de Medellín con los que residen por fuera de este lugar, con el fin de plantear un modelo de atención para el seguimiento por medio de la telemedicina. Métodos: estudio descriptivo, retrospectivo y de un único centro. Se determinó la tasa de supervivencia mediante las curvas de Kaplan-Meier. Resultados: durante el período 2005-2015 se realizaron 754 trasplantes, el 42 % vivía por fuera del área metropolitana. Al agrupar esta cohorte según el lugar de residencia, se observó que la supervivencia de los pacientes residentes en el área metropolitana a 1, 3 y 5 años fue del 96,8 %, 93,7 % y 91,8 %, respectivamente, en contraste con el 94,4 %, 90,3 % y 85,2 % de los del área rural. Esta diferencia fue estadísticamente significativa a favor de los que viven en Medellín (log-rank test p = 0,048; Hazard ratio = 1,68; IC 95 % 0,99-2,84, p = 0,052). Conclusión: la supervivencia fue inferior en los pacientes trasplantados renales que viven por fuera del área Metropolitana. Lo anterior motiva el desarrollo de un modelo de atención para estos pacientes mediado por la telemedicina para facilitar el acceso al seguimiento postrasplante.

Background: Kidney transplantation is the treatment of choice for end-stage renal disease. An adequate post-transplant follow-up improves the graft and patient's long-term survival. Objective: The aim of this study was to compare the outcomes of kidney transplant patients who live in the Medellin metropolitan area with those who live outside this area, to propose a model for follow-up care through telemedicine. Methods: Descriptive, retrospective and one-center study. Kaplan-Meier method was used to determine the survival rate. Results: Between 2005 and 2015, 742 patients were transplanted, 42% of whom lived outside the metropolitan area. The survival rates after 1, 3 and 5 years of treatment in patients in the metropolitan area of Medellín compared to those outside were 96.8%, 93.7% y 91.8% and 94.4%, 90.3% y 85.2% respectively, with statistically significant differences (Log-rank test p=0.048, Hazard ratio 1.68, IC 95% 0.99-2.84, p=0.052). Conclusion: The survival rate was lower in kidney transplant patients living outside the urban area. These findings motivate the development of a telemedicine project to facilitate the follow-up of these patients after a kidney transplantation.

Single-cell spatial proteomic imaging for human neuropathology.

Neurodegenerative disorders are characterized by phenotypic changes and hallmark proteopathies. Quantifying these in archival human brain tissues remains indispensable for validating animal models and understanding disease mechanisms. We present a framework for nanometer-scale, spatial proteomics with multiplex ion beam imaging (MIBI) for capturing neuropathological features. MIBI facilitated simultaneous, quantitative imaging of 36 proteins on archival human hippocampus from individuals spanning cognitively normal to dementia. Customized analysis strategies identified cell types and proteopathies in the hippocampus across stages of Alzheimer's disease (AD) neuropathologic change. We show microglia-pathologic tau interactions in hippocampal CA1 subfield in AD dementia. Data driven, sample independent creation of spatial proteomic regions identified persistent neurons in pathologic tau neighborhoods expressing mitochondrial protein MFN2, regardless of cognitive status, suggesting a survival advantage. Our study revealed unique insights from multiplexed imaging and data-driven approaches for neuropathologic analysis and serves broadly as a methodology for spatial proteomic analysis of archival human neuropathology. TEASER: Multiplex Ion beam Imaging enables deep spatial phenotyping of human neuropathology-associated cellular and disease features.

A 71-Year-Old Man From Ecuador With a History of Type 2 Diabetes Mellitus and Severe COVID-19 Pneumonia and Lung Cavitation Associated With Triple Infection With Trichosporon Asahii, Klebsiella Pneumoniae, and Pseudomonas Aeruginosa.

Unvaccinated patients with comorbidities that impair the immune function, such as type 2 diabetes mellitus, are more likely to develop severe COVID-19. The COVID-19-associated acute respiratory distress syndrome has raised new concerns in intensive care units globally owing to the presence of secondary fungal infections. We report the case of a 71-year-old man from Ecuador with a history of type 2 diabetes mellitus, severe COVID-19 pneumonia, and lung cavitation associated with triple infections with Trichosporon asahii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The patient with a history of high blood pressure and type 2 diabetes was admitted to our hospital from a private care center with a diagnosis of COVID-19-associated acute respiratory distress syndrome. On arrival, the patient presented with signs of hypoxemic respiratory failure. During his stay at another hospital, he had received tocilizumab and corticosteroid therapy. Therefore, intubation was performed and mechanical ventilation was initiated. The patient developed a septic shock and renal failure with a glomerular filtration rate of 27.5 mL/min/1.73 m2; therefore, two hemodiafiltration sessions were started. The bronchoalveolar lavage revealed erythematous lesions in the bronchial tree and abundant purulent secretions and erosions in the bronchial mucosa, with a cavitary lesion in the right bronchial tree. The bronchoalveolar lavage samples were used to isolate Trichosporon asahii, Klebsiella pneumoniae, and Pseudomonas aeruginosa carbapenemase class A. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) Biotyper mass spectrometry and polymerase chain reaction (PCR) molecular identification were performed. This case report suggested that patients with severe COVID-19 pneumonia, with or without comorbidities, are more susceptible to opportunistic infections.

Noninvasive Mechanical Ventilation with Average Volume-Assured Pressure Support versus BiPAP S/T in De Novo Hypoxemic Respiratory Failure.

Background: Bilevel positive airway pressure in spontaneous/time and average volume-assured pressure support (BiPAP·S/T-AVAPS) could maintain an adequate tidal volume by reducing the patient's inspiratory effort; however, this ventilatory strategy has not been compared with other ventilatory modes, especially the conventional BiPAP S/T mode, when noninvasive mechanical ventilation (NIMV) is used. The primary objective of this study was to determine the rate of success and failure of the use of BiPAP·S/T-AVAPS versus BiPAP·S/T alone in patients with mild-to-moderate "de novo" hypoxemic respiratory failure. Methods: This was a matched-cohort study. Subjects with mild-to-moderate de novo hypoxemic respiratory failure were divided into two groups according to the ventilatory strategy used. The subjects in the BiPAP·S/T group were paired with those in the BiPAP·S/T-AVAPS group. Results: A total of 58 subjects were studied. Twenty-nine subjects in the BiPAP·S/T group were paired with 29 subjects in the BiPAP·S/T-AVAPS group. Twenty patients (34.5%) presented with "failure of NIMV," while 38 (65.5%) patients did not. In addition, 13 (22.4%) patients died, while 45 (77.6%) recovered. No differences were found in the percentage of intubation (P=0.44) and mortality (P=0.1). Conclusion: The BiPAP S/T-AVAPS ventilator mode was not superior to the BiPAP·S/T mode. A high mortality rate was observed in patients with NIMV failure in both modes. This trial is registered with https://doi.org/10.1186/ISRCTN17904857.

Innate type 2 immunity controls hair follicle commensalism by Demodex mites.

Demodex mites are commensal parasites of hair follicles (HFs). Normally asymptomatic, inflammatory outgrowth of mites can accompany malnutrition, immune dysfunction, and aging, but mechanisms restricting Demodex outgrowth are not defined. Here, we show that control of mite HF colonization in mice required group 2 innate lymphoid cells (ILC2s), interleukin-13 (IL-13), and its receptor, IL-4Ra-IL-13Ra1. HF-associated ILC2s elaborated IL-13 that attenuated HFs and epithelial proliferation at anagen onset; in their absence, Demodex colonization led to increased epithelial proliferation and replacement of gene programs for repair by aberrant inflammation, leading to the loss of barrier function and HF exhaustion. Humans with rhinophymatous acne rosacea, an inflammatory condition associated with Demodex, had increased HF inflammation with decreased type 2 cytokines, consistent with the inverse relationship seen in mice. Our studies uncover a key role for skin ILC2s and IL-13, which comprise an immune checkpoint that sustains cutaneous integrity and restricts pathologic infestation by colonizing HF mites.

Mass cytometry reveals a conserved immune trajectory of recovery in hospitalized COVID-19 patients.

While studies have elucidated many pathophysiological elements of COVID-19, little is known about immunological changes during COVID-19 resolution. We analyzed immune cells and phosphorylated signaling states at single-cell resolution from longitudinal blood samples of patients hospitalized with COVID-19, pneumonia and/or sepsis, and healthy individuals by mass cytometry. COVID-19 patients showed distinct immune compositions and an early, coordinated, and elevated immune cell signaling profile associated with early hospital discharge. Intra-patient longitudinal analysis revealed changes in myeloid and T cell frequencies and a reduction in immune cell signaling across cell types that accompanied disease resolution and discharge. These changes, together with increases in regulatory T cells and reduced signaling in basophils, also accompanied recovery from respiratory failure and were associated with better outcomes at time of admission. Therefore, although patients have heterogeneous immunological baselines and highly variable disease courses, a core immunological trajectory exists that defines recovery from severe SARS-CoV-2 infection.

Quality of red tilapia viscera oil (Oreochromis sp.) as a function of extraction methods.

This study aimed to propose a simple and efficient heating-freezing method for oil recovery from red tilapia (Oreochromis sp.) viscera, suitable for industrial application and that does not affect its composition. Three methodologies for oil extraction were studied: a) direct heating (69 °C and 29 min) of samples followed by separation of the oil by decantation, b) direct heating with subsequent freezing and c) solvent extraction assisted by ultrasound. For the oil obtained by each methodology, the following factors were determined: peroxide and iodine values, oxidative stability index, yield percentages and fatty acid profile and, to evaluate the changes thereof, a thermal analysis by differential scanning calorimetry was performed. An oil extracted by centrifugation from fresh viscera was used as control. Results showed yields of 92,126%, 60,99% and 55,36% for the oil obtained by heating and freezing, heating and decanting and solvent extraction, respectively, the other evaluated parameters were similar among each other. The content of PUFA was not affected by heating when compared to the control oil, although a decrease was observed in the solvent extracted oil. This behavior was corroborated with the thermal analysis, which showed that the higher PUFA content, the lower the melting temperatures of the oils and the energy required for phase change. A principal component analysis allowed determining that while there are no differences in the abundance of fatty acids C20:1, 14:0, 18:0, 16:1 and C16:0, there are differences for fatty acids C18:1 and C18:2 depending on the method of extraction used in the oil obtention. The results of this study show that the heating-freezing extraction method is a good alternative for acquiring value-added products and facilitates their implementation in rural areas. Furthermore, allows obtaining a product with high content of polyunsaturated fatty acids (at least a third of the total content).

Successive Fermentation of Aguamiel and Molasses by Aspergillus oryzae and Saccharomyces cerevisiae to Obtain High Purity Fructooligosaccharides.

Fructooligosaccharides (FOS) are usually synthesized with pure enzymes using highly concentrated sucrose solutions. In this work, low-cost aguamiel and molasses were explored as sucrose alternatives to produce FOS, via whole-cell fermentation, with an Aspergillus oryzae DIA-MF strain. FOS production process was optimized through a central composite experimental design, with two independent variables: initial sucrose concentration in a medium composed of aguamiel and molasses (AgMe), and inoculum concentration. The optimized process-165 g/L initial sucrose in AgMe (adjusted with concentrated molasses) and 1 × 107 spores/mL inoculum concentration-resulted in an FOS production of 119 ± 12 g/L and a yield of 0.64 ± 0.05 g FOS/g GFi. Among the FOSs produced were kestose, nystose, 1-fructofuranosyl-nystose, and potentially a novel trisaccharide produced by this strain. To reduce the content of mono- and disaccharides in the mixture, run a successive fermentation was run with two Saccharomyces cerevisiae strains. Fermentations run with S. cerevisiae S227 improved FOS purity in the mixture from 39 ± 3% to 61.0 ± 0.6% (w/w) after 16 h of fermentation. This study showed that agro-industrial wastes such as molasses with aguamiel are excellent alternatives as substrate sources for the production of prebiotic FOS, resulting in a lower-cost process.

Influence of Self-MHC Class I Recognition on the Dynamics of NK Cell Responses to Cytomegalovirus Infection.

Although interactions between inhibitory Ly49 receptors and their self-MHC class I ligands in C57BL/6 mice are known to limit NK cell proliferation during mouse CMV (MCMV) infection, we created a 36-marker mass cytometry (CyTOF) panel to investigate how these inhibitory receptors impact the NK cell response to MCMV in other phenotypically measurable ways. More than two thirds of licensed NK cells (i.e., those expressing Ly49C, Ly49I, or both) in uninfected mice had already differentiated into NK cells with phenotypes indicative of Ag encounter (KLRG1+Ly6C-) or memory-like status (KLRG1+Ly6C+). These pre-existing KLRG1+Ly6C+ NK cells resembled known Ag-specific memory NK cell populations in being less responsive to IL-18 and IFN-α stimulation in vitro and by selecting for NK cell clones with elevated expression of a Ly49 receptor. During MCMV infection, the significant differences between licensed and unlicensed (Ly49C-Ly49I-) NK cells disappeared within both CMV-specific (Ly49H+) and nonspecific (Ly49H-) responses. This lack of heterogeneity carried into the memory phase, with only a difference in CD16 expression manifesting between licensed and unlicensed MCMV-specific memory NK cell populations. Our results suggest that restricting proliferation is the predominant effect licensing has on the NK cell population during MCMV infection, but the inhibitory Ly49-MHC interactions that take place ahead of infection contribute to their limited expansion by shrinking the pool of licensed NK cells capable of robustly responding to new challenges.

A conserved immune trajectory of recovery in hospitalized COVID-19 patients.

Many studies have provided insights into the immune response to COVID-19; however, little is known about the immunological changes and immune signaling occurring during COVID-19 resolution. Individual heterogeneity and variable disease resolution timelines obscure unifying immune characteristics. Here, we collected and profiled >200 longitudinal peripheral blood samples from patients hospitalized with COVID-19, with other respiratory infections, and healthy individuals, using mass cytometry to measure immune cells and signaling states at single cell resolution. COVID-19 patients showed a unique immune composition and an early, coordinated and elevated immune cell signaling profile, which correlated with early hospital discharge. Intra-patient time course analysis tied to clinically relevant events of recovery revealed a conserved set of immunological processes that accompany, and are unique to, disease resolution and discharge. This immunological process, together with additional changes in CD4 regulatory T cells and basophils, accompanies recovery from respiratory failure and is associated with better clinical outcomes at the time of admission. Our work elucidates the biological timeline of immune recovery from COVID-19 and provides insights into the fundamental processes of COVID-19 resolution in hospitalized patients.