T cell perturbations persist for at least 6 months following hospitalization for COVID-19

Comprehensive Characterization of Innate and Adaptive Immune Profiles in the Pediatric COVID-19 Convalescent Phase

BACKGROUND

Knowledge of the effect of SARS-CoV-2 on the innate and adaptive immune responses of children is currently lacking. We investigated the immune profile of recovered pediatric patients 3 to 11 weeks after acute COVID-19.

METHODS

Children who were previously healthy or had a preexisting chronic disease and had a positive reverse transcription polymerase chain reaction/serology were enrolled (n=23). The control group was composed of 25 patients without COVID-19 paired by age, sex and baseline chronic conditions. We performed immunophenotyping, hematologic and inflammatory markers analysis, cytokines and T-cell receptor excision circle (TREC) quantifications.

RESULTS

Most COVID-19 convalescent pediatric patients (COVID-19 CPP) had chronic conditions (73.9%), as well as 80% of the controls. Five children developed multisystem inflammatory syndrome in children. COVID-19 CPP had higher lymphocyte numbers than controls due to an increase in CD4+ T cells. Naive, effector memory (EM) reexpressing CD45RA T cells and follicular CD4+ T cells, as well as TRECs and HLA-DR+ and CD38+CD4+ activated T lymphocytes, were increased in those patients. EM2 and EM3 CD4+ T cells, EM2 CD8+ T cells and memory B cells were elevated in the COVID-19 CPP group. Numbers of neutrophils, monocytes and natural killer cells were equivalent but with increased activation in the recovered patients.

CONCLUSIONS

In the short-term following infection, COVID-19-recovered patients show persistent activation profiles in phagocytes, T-cell subtypes and natural killer cells. Meanwhile, increased production of lymphocytes, TRECs and naive T cells suggests immune response recovery, even in immunosuppressed patients and children with comorbidities. The clinical implications of these findings should be further studied.

Reduced immune response to SARS-CoV-2 infection in the elderly after 6 months

Objectives

To evaluate the immune persistence and cross-immune response of elderly individuals after Omicron BA.5 infections.

Method

The neutralizing antibodies against WT, BA.5, XBB.1 and EG.5 strains were analyzed. The T/B-cell subsets' responses were tested through intracellular cytokine staining and flow cytometry.

Results

The neutralizing antibodies titers against WT and BA.5 strain, remaining high level for at least 6 months, were higher than that of both XBB.1 and EG.5 variants. The neutralizing antibodies of WT, BA.5, XBB.1, and EG.5 strains in the elderly were slightly lower than those in middle-age. The memory B cells decreased rapidly in the elderly, and Tfh, Th17 cells of the elderly continued to increase for only 3 months, while Tfh and Th17 cells increased in the middle-aged for over 6 months. For the elderly, after peptide stimulation, unswitched/switched memory B cells decreased, while double negative B cells displayed higher proliferation. The proportions of both naïve and Temra cells in CD4+ and CD8+ T cells declined, whereas those of Tcm and Tem cells elevated. In the meantime, both CD69+ and CD38+ T cells decreased, but the frequencies of PD-1+ and CTLA-4+ of CD4+ and CD8+ T cells showed an increasing trend. The proportions of PD-1+ and CTLA-4+ cells also increased in older people with long COVID symptoms at 3m post-infection.

Conclusions

Omicron BA.5 infection induced lower neutralizing antibodies against XBB.1 and EG.5 variant. The decrease of memory B cells, CD69+ and CD38+T cells, as well as the increase of PD-1+, CTLA-4+ of CD4+/CD8+T cells and double negative B cells, indicate that sustained immune responses against BA.5 infection may wane more rapidly in elderly populations.

The Impact of Vaccination Frequency on COVID-19 Public Health Outcomes: A Model-Based Analysis

Background: While the rapid deployment of SARS-CoV-2 vaccines had a significant impact on the ongoing COVID-19 pandemic, rapid viral immune evasion and waning neutralizing antibody titers have degraded vaccine efficacy. Nevertheless, vaccine manufacturers and public health authorities have a number of options at their disposal to maximize the benefits of vaccination. In particular, the effect of booster schedules on vaccine performance bears further study. Methods: To better understand the effect of booster schedules on vaccine performance, we used an agent-based modeling framework and a population pharmacokinetic model to simulate the impact of boosting frequency on the durability of vaccine protection against infection and severe acute disease. Results: Our work suggests that repeated dosing at frequent intervals (three or more times a year) may offset the degradation of vaccine efficacy, preserving the utility of vaccines in managing the ongoing pandemic. Conclusions: Given the practical significance of potential improvements in vaccine utility, clinical research to better understand the effects of repeated vaccination would be highly impactful. These findings are particularly relevant as public health authorities worldwide have reduced the frequency of boosters to once a year or less.

Phenotypic Timeline Kinetics, Integrative Networks, and Performance of T- and B-Cell Subsets Associated with Distinct Clinical Outcome of Severe COVID-19 Patients

The present study aimed to evaluate the kinetics of the phenotypic profile and integrative networks of T/B-cells in severe COVID-19 patients, categorized according to disease outcome, during the circulation of the B.1.1.28 and B.1.1.33 SARS-CoV-2 strains in Brazil. Peripheral blood obtained at distinct time points (baseline/D0; D7; D14-28) was used for ex vivo flow cytometry immunophenotyping. The data demonstrated a decrease at D0 in the frequency of CD3+ T-cells and CD4+ T-cells and an increase in B-cells with mixed activation/exhaustion profiles. Higher changes in B-cell and CD4+ T-cells at D7 were associated with discharge/death outcomes, respectively. Regardless of the lower T/B-cell connectivity at D0, distinct profiles from D7/D14-28 revealed that, while discharge was associated with increasing connectivity for B-cells, CD4+ and CD8+ T-cells death was related to increased connectivity involving B-cells, but with lower connections mediated by CD4+ T-cells. The CD4+CD38+ and CD8+CD69+ subsets accurately classified COVID-19 vs. healthy controls throughout the kinetic analysis. Binary logistic regression identified CD4+CD107a+, CD4+T-bet+, CD8+CD69+, and CD8+T-bet+ at D0 and CD4+CD45RO+CD27+ at D7 as subsets associated with disease outcomes. Results showed that distinct phenotypic timeline kinetics and integrative networks of T/B-cells are associated with COVID-19 outcomes that may subsidize the establishment of applicable biomarkers for clinical/therapeutic monitoring.

Impact of COVID-19 Interventions on Respiratory and Intestinal Infectious Disease Notifications - Jiangsu Province, China, 2020-2023

Introduction

Many measures implemented to control the coronavirus disease 2019 (COVID-19) pandemic have reshaped the epidemic patterns of other infectious diseases. This study estimated the impact of the COVID-19 pandemic on respiratory and intestinal infectious diseases and potential changes following reopening.

Methods

The optimal intervention and counterfactual models were selected from the seasonal autoregressive integrated moving average (SARIMA), neural network autoregression (NNAR), and hybrid models based on the minimum mean absolute percentage error (MAPE) in the test set. The relative change rate between the actual notification rate and that predicted by the optimal model was calculated for the entire COVID-19 epidemic prevention period and the "reopening" period.

Results

Compared with the predicted notification rate based on the counterfactual model, the total relative change rates for the 9 infectious diseases were -44.24%, respiratory infections (-55.41%), and intestinal infections (-26.59%) during 2020-2022. Compared with the predicted notification rate based on the intervention model, the total relative change rates were +247.98%, respiratory infections (+389.59%), and intestinal infections (+50.46%) in 2023. Among them, the relative increases in influenza (+499.98%) and hand-foot-mouth disease (HFMD) (+70.97%) were significant.

Conclusions

Measures taken in Jiangsu Province in response to COVID-19 effectively constrained the spread of respiratory and intestinal infectious diseases. Influenza and HFMD rebounded significantly after the lifting of COVID-19 intervention restrictions.

Changes in the epidemiology of pediatric brain abscesses pre- and post-COVID-19 pandemic: a single-center study

BACKGROUND

An increased incidence of brain abscesses was observed post-COVID-19 pandemic. However, it remains unclear how the COVID-19 pandemic influenced the epidemiology of brain abscesses. This study aimed to investigate changes in the epidemiology of brain abscesses pre- and post-COVID-19 pandemic.

METHODS

A retrospective study of demographic, clinical, radiological, and laboratory characteristics of patients with brain abscesses in Children's Hospital of Soochow University from 2015-2023 was performed.

RESULTS

A total of 34 patients were admitted to the hospital during the study. The post-COVID-19 cohort had an average of 5.5 cases/year, which is a 129.2% increase compared to the pre-COVID-19 cohort's average of 2.4 cases/year. Additionally, the rates of fever upon admission (86.36% vs 50%, p = 0.04) and experiencing high-grade fever within 6 weeks before admission (40.91% vs 8.33%, p = 0.044) were significantly increased. A potential rise in the rate of intensive care unit admission was observed (36.36% vs 8.33%, p = 0.113). The average value of globulin in the post-COVID cohort was significantly higher compared to the pre-COVID cohort (31.60 ± 5.97 vs 25.50 ± 5.08, p = 0.009). Streptococcal infections were the predominant cause of brain abscesses in both cohorts (40% vs 43.75%, p = 0.57).

CONCLUSIONS

There was a significant increase in the number of brain abscess patients after the COVID-19 pandemic. This underscores the importance of children receiving the streptococcal vaccine.

Peripheral Blood Mononuclear Cells and Serum Cytokines in Patients with Lupus Nephritis after COVID-19

Systemic lupus erythematosus (SLE) patients have an increased risk of infections and infection-related mortality. Therefore, during the global SARS-CoV-2 pandemic, SLE patients were particularly vulnerable to SARS-CoV-2 infections. Also, compared to other patients, SLE patients seem to develop more severe manifestations of coronavirus disease 2019 (COVID-19), with higher rates of hospitalization, invasive ventilation requirements, or death. This study evaluated the immune parameters after SARS-CoV-2 infection in SLE patients. We analyzed subpopulations of peripheral blood cells collected from patients with renal manifestation of SLE (lupus nephritis, LN). LN patients were divided into two subgroups: those unexposed to SARS-CoV-2 (LN CoV-2(-)) and those who had confirmed COVID-19 (LN-CoV-2(+)) six months earlier. We analyzed basic subpopulations of T cells, B cells, monocytes, dendritic cells (DCs), and serum cytokines using flow cytometry. All collected data were compared to a healthy control group without SARS-CoV-2 infection in medical history. LN patients were characterized by a decreased percentage of helper T (Th) cells and an increased percentage of cytotoxic T (Tc) cells regardless of SARS-CoV-2 infection. LN CoV-2(+) patients had a higher percentage of regulatory T cells (Tregs) and plasmablasts (PBs) and a lower percentage of non-switched memory (NSM) B cells compared to LN CoV-2(-) patients or healthy controls (HC CoV-2(-)). LN patients had a higher percentage of total monocytes compared with HC CoV-2(-). LN CoV-2(+) patients had a higher percentage of classical and intermediate monocytes than LN CoV-2(-) patients and HC CoV-2(-). LN CoV-2(+) patients had higher serum IL-6 levels than HC CoV-2(-), while LN CoV-2(-) patients had higher levels of serum IL-10. LN patients are characterized by disturbances in the blood's basic immunological parameters. However, SARS-CoV-2 infection influences B-cell and monocyte compartments.

CD74 is a functional MIF receptor on activated CD4+ T cells

Next to its classical role in MHC II-mediated antigen presentation, CD74 was identified as a high-affinity receptor for macrophage migration inhibitory factor (MIF), a pleiotropic cytokine and major determinant of various acute and chronic inflammatory conditions, cardiovascular diseases and cancer. Recent evidence suggests that CD74 is expressed in T cells, but the functional relevance of this observation is poorly understood. Here, we characterized the regulation of CD74 expression and that of the MIF chemokine receptors during activation of human CD4+ T cells and studied links to MIF-induced T-cell migration, function, and COVID-19 disease stage. MIF receptor profiling of resting primary human CD4+ T cells via flow cytometry revealed high surface expression of CXCR4, while CD74, CXCR2 and ACKR3/CXCR7 were not measurably expressed. However, CD4+ T cells constitutively expressed CD74 intracellularly, which upon T-cell activation was significantly upregulated, post-translationally modified by chondroitin sulfate and could be detected on the cell surface, as determined by flow cytometry, Western blot, immunohistochemistry, and re-analysis of available RNA-sequencing and proteomic data sets. Applying 3D-matrix-based live cell-imaging and receptor pathway-specific inhibitors, we determined a causal involvement of CD74 and CXCR4 in MIF-induced CD4+ T-cell migration. Mechanistically, proximity ligation assay visualized CD74/CXCR4 heterocomplexes on activated CD4+ T cells, which were significantly diminished after MIF treatment, pointing towards a MIF-mediated internalization process. Lastly, in a cohort of 30 COVID-19 patients, CD74 surface expression was found to be significantly upregulated on CD4+ and CD8+ T cells in patients with severe compared to patients with only mild disease course. Together, our study characterizes the MIF receptor network in the course of T-cell activation and reveals CD74 as a novel functional MIF receptor and MHC II-independent activation marker of primary human CD4+ T cells.

Comparative Analysis of Lymphocyte Populations in Post-COVID-19 Condition and COVID-19 Convalescent Individuals

Reduced lymphocyte counts in peripheral blood are one of the most common observations in acute phases of viral infections. Although many studies have already examined the impact of immune (dys)regulation during SARS-CoV-2 infection, there are still uncertainties about the long-term consequences for lymphocyte homeostasis. Furthermore, as persistent cellular aberrations have been described following other viral infections, patients with "Post-COVID-19 Condition" (PCC) may present similarly. In order to investigate cellular changes in the adaptive immune system, we performed a retrospective analysis of flow cytometric data from lymphocyte subpopulations in 106 patients with confirmed SARS-CoV-2 infection who received medical care at our institution. The patients were divided into three groups according to the follow-up date; laboratory analyses of COVID-19 patients were compared with 28 unexposed healthy controls. Regarding B lymphocyte subsets, levels of IgA + CD27+, IgG + CD27+, IgM + CD27- and switched B cells were significantly reduced at the last follow-up compared to unexposed healthy controls (UHC). Of the 106 COVID-19 patients, 56 were clinically classified as featuring PCC. Significant differences between PCC and COVID-19 convalescents compared to UHC were observed in T helper cells and class-switched B cells. However, we did not detect specific or long-lasting immune cellular changes in PCC compared to the non-post-COVID-19 condition.

Differential peripheral memory T cell subsets sensitively indicate the severity of nonalcoholic fatty liver disease

AIM

Differential patterns of peripheral memory T cell subsets in nonalcoholic fatty liver disease (NAFLD) were assessed using flow cytometry (FCM) to elucidate their association with NAFLD severity and provide a new noninvasive method to sensitively detect the disease severity in addition to existing biomarkers.

METHODS

We assessed the differential frequencies of peripheral memory T cell subsets in 103 patients with NAFLD according to the degree of liver fibrosis (FIB) using FCM analysis. We focused on the following populations: CCR7+ CD45RA+ naïve T, CCR7+ CD45RA- central memory T cells (TCM), CCR7- CD45RA- effector memory T, and CCR7- CD45RA+ terminally differentiated effector memory T (TEMRA) cells in CD4+ and CD8+ T, Th1, Th2, and Th17 cells, respectively. To evaluate the pathological progression of the disease, these frequencies were also examined according to the degree of the NAFLD activity score (NAS).

RESULTS

Several significant correlations were observed between laboratory parameters and peripheral memory T lymphocyte frequencies according to the degree of liver FIB and NAS in NAFLD. In univariate and multivariate analyses, the frequency of CD8+ TEMRA cells predicted severe FIB, and the predictive power was validated in an independent cohort. Furthermore, the frequencies of several memory T cell subsets sensitively indicated the pathological progression of NAFLD (Th17 TCM: steatosis, CD4+ TCM: lobular inflammation, and CD8+ TEMRA and effector memory T cells: hepatocellular ballooning).

CONCLUSIONS

Our results suggest that the analysis of peripheral memory T lymphocyte frequencies can noninvasively predict severe FIB and sensitively indicate the pathological progression of NAFLD.

T-cell responses in COVID-19 survivors 6-8 months after infection: A longitudinal cohort study in Pune

BACKGROUND

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immune response is crucial for disease management, although diminishing immunity raises the possibility of reinfection.

METHODS

We examined the immunological response to SARS-CoV-2 in a cohort of convalescent COVID-19 patients in matched samples collected at 1 and 6-8 months after infection. The peripheral blood mononuclear cells were isolated from enrolled study participants and flow cytometry analysis was done to assess the lymphocyte subsets of naive, effector, central memory, and effector memory CD4+ or CD8+ T cells in COVID-19 patients at 1 and 6-8 months after infection. Immunophenotypic characterization of immune cell subsets was performed on individuals who were followed longitudinally for 1 month (n = 44) and 6-8 months (n = 25) after recovery from COVID infection.

RESULTS

We observed that CD4 +T cells in hospitalized SARS-CoV-2 patients tended to decrease, whereas CD8+ T cells steadily recovered after 1 month, while there was a sustained increase in the population of effector T cells and effector memory T cells. Furthermore, COVID-19 patients showed persistently low B cells and a small increase in the NK cell population.

CONCLUSION

Our findings show that T cell responses were maintained at 6-8 months after infection. This opens new pathways for further research into the long-term effects in COVID-19 immunopathogenesis.

SARS-CoV-2 Infection and Postacute Risk of Non-Coronavirus Disease 2019 Infectious Disease Hospitalizations: A Nationwide Cohort Study of Danish Adults Aged ≥50 Years

BACKGROUND

Reports suggest that the potential long-lasting health consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may involve persistent dysregulation of some immune populations, but the potential clinical implications are unknown. We investigated the associated risk of hospitalization due to non-coronavirus disease 2019 (COVID-19) infectious diseases following the postacute phase of SARS-CoV-2 infection.

METHODS

By cross-linking data from the comprehensive Danish test and surveillance system for COVID-19 together with nationwide healthcare and demographic registers, we established a study cohort of 2 430 694 individuals aged ≥50 years, from 1 January 2021 to 10 December 2022, with no evidence of SARS-CoV-2 infection prior to study entry. Using Poisson regression, we compared the outcome rates of non-COVID-19 infectious disease hospitalizations following the acute phase of (a first) SARS-CoV-2 infection (defined as ≥29 days since the day of infection) in recovered individuals with rates among SARS-CoV-2-uninfected individuals.

RESULTS

Among 2 430 694 included individuals (mean age, 66.8 [standard deviation, 11.3] years), 930 071 acquired SARS-CoV-2 infection during follow-up totaling 4 519 913 person-years. The postacute phase of SARS-CoV-2 infection was associated with an incidence rate ratio (IRR) of 0.90 (95% confidence interval [CI]: .88-.92) for any infectious disease hospitalization. Findings (IRR [95% CI]) were similar for upper respiratory tract (1.08 [.97-1.20]), lower respiratory tract (0.90 [.87-.93]), influenza (1.04 [.94-1.15]), gastrointestinal (1.28 [.78-2.09]), skin (0.98 [.93-1.03]), urinary tract (1.01 [.96-1.08]), certain invasive bacterial (0.96 [.91-1.01]), and other (0.96 [.92-1.00]) infectious disease hospitalizations and in subgroups.

CONCLUSIONS

Our study does not support an increased susceptibility to non-COVID-19 infectious disease hospitalization following SARS-CoV-2 infection.

Measurement of IFN-γ and IL-2 for the assessment of the cellular immunity against SARS-CoV-2

The study of specific T-cell responses against SARS-CoV-2 is important for understanding long-term immunity and infection management. The aim of this study was to assess the dual IFN-γ and IL-2 detection, using a SARS-CoV-2 specific fluorescence ELISPOT, in patients undergoing acute disease, during convalescence, and after vaccination. We also evaluated humoral response and compared with T-cells with the aim of correlating both types of responses, and increase the number of specific response detection. Blood samples were drawn from acute COVID-19 patients and convalescent individuals classified according to disease severity; and from unvaccinated and vaccinated uninfected individuals. IgGs against Spike and nucleocapsid, IgMs against nucleocapsid, and neutralizing antibodies were also analyzed. Our results show that IFN-γ in combination with IL-2 increases response detection in acute and convalescent individuals (p = 0.023). In addition, IFN-γ detection can be a useful biomarker for monitoring severe acute patients, as our results indicate that those individuals with a poor outcome have lower levels of this cytokine. In some cases, the lack of cellular immunity is compensated by antibodies, confirming the role of both types of immune responses in infection, and confirming that their dual detection can increase the number of specific response detections. In summary, IFN-γ/IL-2 dual detection is promising for characterizing and assessing the immunization status, and helping in the patient management.

In-depth immune profiling reveals advanced B- and T-cell differentiation to be associated with Th1-driven immune dysregulation in common variable immunodeficiency

Common variable immunodeficiency (CVID) is an inborn error of immunity characterized by low levels of antibodies. In addition to infections, many patients also suffer from T-helper 1-driven immune dysregulation, which is associated with increased mortality. The aim of this study was to perform in-depth characterization of the T and the B cell compartments in a well-defined cohort of patients affected by CVID and correlate the findings to the level of clinical immune dysregulation. We used mass cytometry, targeted proteomics, flow cytometry and functional assays to delineate the immunological phenotype of 15 CVID-affected patients with different levels of immune dysregulation. Unbiased clustering of T cell mass cytometry data correlated with CVID-related immune dysregulation and plasma protein profiles. Expanded CXCR3+ T-bet-expressing B cells correlated with effector memory CD4+ T cell clusters, and increased plasma levels of CXCR3-ligands. Our findings indicate an interplay between B cells and T cells in CVID-related immune dysregulation and provide a better understanding of the underlying pathological mechanisms.

Single-cell RNA-Seq reveals intracellular microbial diversity within immune cells during SARS-CoV-2 infection and recovery

Intracellular microorganisms, like viruses, bacteria, and fungi, pose challenges in detection due to their non-culturable forms. Transcriptomic analysis at cellular level enables exploration of distributions and the impact of these microorganisms on host cells, a domain that remains underexplored because of methodological limitations. Single-cell technology shows promise in addressing this by capturing polyadenine-tailed transcripts, because recent studies confirmed polyadenylation in microbial transcriptomes. We utilized single-cell RNA-seq from PBMCs to probe intracellular microbes in healthy, SARS-CoV-2-positive, and recovered individuals. Among 76 bacterial species detected, 16 showed significant abundance differences. Buchnera aphidicola, Streptomyces clavuligerus, and Ehrlichia canis emerged significantly in memory-B, Naïve-T, and Treg cells. Staphylococcus aureus, Mycoplasma mycoides, Leptospira interrogans, and others displayed elevated levels in SARS-CoV-2-positive patients, suggesting possible disease association. This highlights the strength of single-cell technology in revealing potential microorganism's cell-specific functions. Further research is essential for functional understanding of their cell-specific abundance across physiological states.

Immunological profiling in long COVID: overall low grade inflammation and T-lymphocyte senescence and increased monocyte activation correlating with increasing fatigue severity

Background

Many patients with SARS-CoV-2 infection develop long COVID with fatigue as one of the most disabling symptoms. We performed clinical and immune profiling of fatigued and non-fatigued long COVID patients and age- and sex-matched healthy controls (HCs).

Methods

Long COVID symptoms were assessed using patient-reported outcome measures, including the fatigue assessment scale (FAS, scores ≥22 denote fatigue), and followed up to one year after hospital discharge. We assessed inflammation-related genes in circulating monocytes, serum levels of inflammation-regulating cytokines, and leukocyte and lymphocyte subsets, including major monocyte subsets and senescent T-lymphocytes, at 3-6 months post-discharge.

Results

We included 37 fatigued and 36 non-fatigued long COVID patients and 42 HCs. Fatigued long COVID patients represented a more severe clinical profile than non-fatigued patients, with many concurrent symptoms (median 9 [IQR 5.0-10.0] vs 3 [1.0-5.0] symptoms, p<0.001), and signs of cognitive failure (41%) and depression (>24%). Immune abnormalities that were found in the entire group of long COVID patients were low grade inflammation (increased inflammatory gene expression in monocytes, increased serum pro-inflammatory cytokines) and signs of T-lymphocyte senescence (increased exhausted CD8+ TEMRA-lymphocytes). Immune profiles did not significantly differ between fatigued and non-fatigued long COVID groups. However, the severity of fatigue (total FAS score) significantly correlated with increases of intermediate and non-classical monocytes, upregulated gene levels of CCL2, CCL7, and SERPINB2 in monocytes, increases in serum Galectin-9, and higher CD8+ T-lymphocyte counts.

Conclusion

Long COVID with fatigue is associated with many concurrent and persistent symptoms lasting up to one year after hospitalization. Increased fatigue severity associated with stronger signs of monocyte activation in long COVID patients and potentially point in the direction of monocyte-endothelial interaction. These abnormalities were present against a background of immune abnormalities common to the entire group of long COVID patients.

Pentameric C-reactive protein is a better prognostic biomarker and remains elevated for longer than monomeric CRP in hospitalized patients with COVID-19

The differing roles of the pentameric (p) and monomeric (m) C-reactive protein (CRP) isoforms in viral diseases are not fully understood, which was apparent during the COVID-19 pandemic regarding the clinical course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Herein, we investigated the predictive value of the pCRP and mCRP isoforms for COVID-19 severity in hospitalized patients and evaluated how the levels of the protein isoforms changed over time during and after acute illness. This study utilized samples from a well-characterized cohort of Swedish patients with SARS-CoV-2 infection, the majority of whom had known risk factors for severe COVID-19 and required hospitalization. The levels of pCRP were significantly raised in patients with severe COVID-19 and in contrast to mCRP the levels were significantly associated with disease severity. Additionally, the pCRP levels remained elevated for at least six weeks post inclusion, which was longer compared to the two weeks for mCRP. Our data indicates a low level of inflammation lasting for at least six weeks following COVID-19, which might indicate that the disease has an adverse effect on the immune system even after the viral infection is resolved. It is also clear that the current standard method of testing pCRP levels upon hospitalization is a useful marker for predicting disease severity and mCRP testing would not add any clinical relevance for patients with COVID-19.

[S1 guidelines for the management of postviral conditions using the example of post-COVID-19]

These S1 guidelines are an updated and expanded version of the S1 guidelines on long COVID differential diagnostic and management strategies. They summarize the state of knowledge on postviral conditions like long/post COVID at the time of writing. Due to the dynamic nature of knowledge development, they are intended to be "living guidelines". The focus is on practical applicability at the level of primary care, which is understood to be the appropriate place for initial access and for primary care and treatment. The guidelines provide recommendations on the course of treatment, differential diagnostics of the most common symptoms that can result from infections like with SARS-CoV-2, treatment options, patient management and care, reintegration and rehabilitation. The guidelines have been developed through an interdisciplinary and interprofessional process and provide recommendations on interfaces and possibilities for collaboration.

COVID-19 after rituximab therapy in cSLE patients

Childhood-onset systemic lupus erythematosus (cSLE) is an autoimmune disease associated with significant morbidity and mortality. Rituximab is a B-cell depleting therapy utilized in the treatment of SLE. In adults, rituximab has been associated with increased risk of adverse outcomes in patients who develop coronavirus disease 2019 (COVID-19). We aimed to assess the impact of prior rituximab treatment on clinical outcomes from Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection in children with SLE. To describe the impact of rituximab on outcomes from SARS-CoV-2 infection, we conducted a retrospective study of pediatric SLE patients in our center diagnosed with COVID-19 who had previously received rituximab between February 2019 and October 2022. Patients' clinical characteristics, disease activity, and outcomes were assessed. Of the eight subjects assessed, five required hospitalizations for COVID-19, four required ICU admission, and two were seen in the emergency department for their symptoms. One patient ultimately expired from her illness. The median time between rituximab administration and COVID-19 diagnosis was 3 months. We assessed the clinical outcomes, including the need of ICU admission and fatal outcome, of COVID-19 in our cSLE patient population after rituximab administration. Approximately 60% of our patients required hospitalization for their illness, and seven out of eight patients required healthcare utilization to include hospitalization and/or emergency department visits.

Alterations in the CD56- and CD56+ T Cell Subsets during COVID-19

The effectiveness of the antiviral immune response largely depends on the activation of cytotoxic T cells. The heterogeneous group of functionally active T cells expressing the CD56 molecule (NKT-like cells), that combines the properties of T lymphocytes and NK cells, is poorly studied in COVID-19. This work aimed to analyze the activation and differentiation of both circulating NKT-like cells and CD56- T cells during COVID-19 among intensive care unit (ICU) patients, moderate severity (MS) patients, and convalescents. A decreased proportion of CD56+ T cells was found in ICU patients with fatal outcome. Severe COVID-19 was accompanied by a decrease in the proportion of CD8+ T cells, mainly due to the CD56- cell death, and a redistribution of the NKT-like cell subset composition with a predominance of more differentiated cytotoxic CD8+ T cells. The differentiation process was accompanied by an increase in the proportions of KIR2DL2/3+ and NKp30+ cells in the CD56+ T cell subset of COVID-19 patients and convalescents. Decreased percentages of NKG2D+ and NKG2A+ cells and increased PD-1 and HLA-DR expression levels were found in both CD56- and CD56+ T cells, and can be considered as indicators of COVID-19 progression. In the CD56- T cell fraction, increased CD16 levels were observed in MS patients and in ICU patients with lethal outcome, suggesting a negative role for CD56-CD16+ T cells in COVID-19. Overall, our findings suggest an antiviral role of CD56+ T cells in COVID-19.

The intersection of obesity and (long) COVID-19: Hypoxia, thrombotic inflammation, and vascular endothelial injury

The role of hypoxia, vascular endothelial injury, and thrombotic inflammation in worsening COVID-19 symptoms has been generally recognized. Damaged vascular endothelium plays a crucial role in forming in situ thrombosis, pulmonary dysfunction, and hypoxemia. Thrombotic inflammation can further aggravate local vascular endothelial injury and affect ventilation and blood flow ratio. According to the results of many studies, obesity is an independent risk factor for a variety of severe respiratory diseases and contributes to high mechanical ventilation rate, high mortality, and slow recovery in COVID-19 patients. This review will explore the mechanisms by which obesity may aggravate the acute phase of COVID-19 and delay long COVID recovery by affecting hypoxia, vascular endothelial injury, and thrombotic inflammation. A systematic search of PubMed database was conducted for papers published since January 2020, using the medical subject headings of "COVID-19" and "long COVID" combined with the following keywords: "obesity," "thrombosis," "endothelial injury," "inflammation," "hypoxia," "treatment," and "anticoagulation." In patients with obesity, the accumulation of central fat restricts the expansion of alveoli, exacerbating the pulmonary dysfunction caused by SARS-CoV-2 invasion, inflammatory damage, and lung edema. Abnormal fat secretion and immune impairment further aggravate the original tissue damage and inflammation diffusion. Obesity weakens baseline vascular endothelium function leading to an early injury and pre-thrombotic state after infection. Enhanced procoagulant activity and microthrombi promote early obstruction of the vascular. Obesity also prolongs the duration of symptoms and increases the risk of sequelae after hospital discharge. Persistent viral presence, long-term inflammation, microclots, and hypoxia may contribute to the development of persistent symptoms, suggesting that patients with obesity are uniquely susceptible to long COVID. Early interventions, including supplemental oxygen, comprehensive antithrombotic therapy, and anti-inflammatory drugs, show effectiveness in many studies in the prevention of serious hypoxia, thromboembolic events, and systemic inflammation, and are therefore recommended to reduce intensive care unit admission, mortality, and sequelae.

Major alterations to monocyte and dendritic cell subsets lasting more than 6 months after hospitalization for COVID-19

Introduction

After more than two years the Coronavirus disease-19 (COVID-19) pandemic continues to burden healthcare systems and economies worldwide, and it is evident that the effects on the immune system can persist for months post-infection. The activity of myeloid cells such as monocytes and dendritic cells (DC) is essential for correct mobilization of the innate and adaptive responses to a pathogen. Impaired levels and responses of monocytes and DC to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is likely to be a driving force behind the immune dysregulation that characterizes severe COVID-19.

Methods

Here, we followed a cohort of COVID-19 patients hospitalized during the early waves of the pandemic for 6-7 months. The levels and phenotypes of circulating monocyte and DC subsets were assessed to determine both the early and long-term effects of the SARS-CoV-2 infection.

Results

We found increased monocyte levels that persisted for 6-7 months, mostly attributed to elevated levels of classical monocytes. Myeloid derived suppressor cells were also elevated over this period. While most DC subsets recovered from an initial decrease, we found elevated levels of cDC2/cDC3 at the 6-7 month timepoint. Analysis of functional markers on monocytes and DC revealed sustained reduction in program death ligand 1 (PD-L1) expression but increased CD86 expression across almost all cell types examined. Finally, C-reactive protein (CRP) correlated positively to the levels of intermediate monocytes and negatively to the recovery of DC subsets.

Conclusion

By exploring the myeloid compartments, we show here that alterations in the immune landscape remain more than 6 months after severe COVID-19, which could be indicative of ongoing healing and/or persistence of viral antigens.