Inflammation/Coagulopathy/Immunology Responsive Index Predicts Poor COVID-19 Prognosis

Persistent CD19+ B cell lymphopenia in critically ill COVID-19 patients 50 days after symptom onset

Introduction

Long COVID (LC) poses a persistent challenge in clinical practice due to limited understanding of its etiology. LC is hypothesized to stem from aberrant immune responses in COVID-19. Vaccinations, which boost immune cells to restore function, could help ease LC symptoms.

Methods

To exclude the impact of vaccination, we examined the immune cell profiles of recovering COVID-19 patients before vaccines were available. White blood cell differentials were monitored in ninety-twohealthy unvaccinated controls. Seventy-six unvaccinated COVID-19 patients were monitored upon admission and on the 50th day post-symptom onset (DPSO50). Peripheral lymphocyte subsets were analyzed using flow cytometry.

Results

Mild cases showed no significant changes in lymphocyte counts or subsets from admission to DPSO50. By DPSO50, severe and critical cases showed almost complete recovery from lymphopenia, with critical cases having CD19+ B-cell counts approximately 45% lower than the mild group. Severe and critical cases exhibited reduced B-cell frequencies, with critical cases displaying around 48% higher natural killer (NK) cell counts. In mild cases, NK cell counts negatively correlated with B-cell counts (r=-0.528, p=0.02). Additionally, critical cases showed positive correlations between NK cell counts and CD4+ T-cell counts (r=0.83, p<0.01), and between NK cell counts and CD8+ T-cell counts (r=0.74, p<0.01). Severe cases demonstrated decreased counts of CD4+CD25+CD127lowFoxP3+ regulatory T-cells (Tregs), which positively correlated with B-cell counts (r=0.37, p<0.05).

Discussion

Our findings indicate that aberrant immune cell profiles in COVID-19 patients change dynamically during recovery, depending on disease severity. This study suggests that convalescent patients from critical COVID-19 may experience long-lasting B-cell lymphopenia.

Crosstalk between the plasminogen/plasmin system and inflammation resolution

The plasminogen/plasmin (Plg/Pla) system, best known for its classical role in thrombolysis, has been recently highlighted as a regulator of other biological processes in mammals, including key steps involved in the resolution of inflammation. Inflammation resolution is a complex process coordinated by different cellular effectors, notably leukocytes, and active mediators, and is initiated shortly after the inflammatory response begins. Once the inflammatory insult is eliminated, an effective and timely engagement of proresolution programs prevents persistent inflammation, thereby avoiding excessive tissue damage, fibrosis, and the development of autoimmunity. Interestingly, recent studies demonstrate that Plg/Pla and their receptor, plasminogen receptor KT (Plg-RKT), regulate key steps in inflammation resolution. The number of studies investigating the involvement of the Plg/Pla system in these and other aspects of inflammation, including degradation of extracellular matrices, immune cell migration, wound healing, and skeletal growth and maintenance, highlights key roles of the Plg/Pla system during physiological and pathologic conditions. Here, we discuss robust evidence in the literature for the emerging roles of the Plg/Pla system in key steps of inflammation resolution. These findings suggest that dysregulation in Plg production and its activation plays a role in the pathogenesis of inflammatory diseases. Elucidating central mechanisms underlying the role of Plg/Pla in key steps of inflammation resolution either in preclinical models of inflammation or in human inflammatory conditions, can provide a rationale for the development of new pharmacologic interventions to promote resolution of inflammation, and open new pathways for the treatment of thromboinflammatory conditions.

Prognostic models in COVID-19 infection that predict severity: a systematic review

Current evidence on COVID-19 prognostic models is inconsistent and clinical applicability remains controversial. We performed a systematic review to summarize and critically appraise the available studies that have developed, assessed and/or validated prognostic models of COVID-19 predicting health outcomes. We searched six bibliographic databases to identify published articles that investigated univariable and multivariable prognostic models predicting adverse outcomes in adult COVID-19 patients, including intensive care unit (ICU) admission, intubation, high-flow nasal therapy (HFNT), extracorporeal membrane oxygenation (ECMO) and mortality. We identified and assessed 314 eligible articles from more than 40 countries, with 152 of these studies presenting mortality, 66 progression to severe or critical illness, 35 mortality and ICU admission combined, 17 ICU admission only, while the remaining 44 studies reported prediction models for mechanical ventilation (MV) or a combination of multiple outcomes. The sample size of included studies varied from 11 to 7,704,171 participants, with a mean age ranging from 18 to 93 years. There were 353 prognostic models investigated, with area under the curve (AUC) ranging from 0.44 to 0.99. A great proportion of studies (61.5%, 193 out of 314) performed internal or external validation or replication. In 312 (99.4%) studies, prognostic models were reported to be at high risk of bias due to uncertainties and challenges surrounding methodological rigor, sampling, handling of missing data, failure to deal with overfitting and heterogeneous definitions of COVID-19 and severity outcomes. While several clinical prognostic models for COVID-19 have been described in the literature, they are limited in generalizability and/or applicability due to deficiencies in addressing fundamental statistical and methodological concerns. Future large, multi-centric and well-designed prognostic prospective studies are needed to clarify remaining uncertainties.

Establishment of the large-scale longitudinal multi-omics dataset in COVID-19 patients: data profile and biospecimen

Understanding and monitoring virus-mediated infections has gained importance since the global outbreak of the coronavirus disease 2019 (COVID-19) pandemic. Studies of high-throughput omics-based immune profiling of COVID-19 patients can help manage the current pandemic and future virus-mediated pandemics. Although COVID-19 is being studied since past 2 years, detailed mechanisms of the initial induction of dynamic immune responses or the molecular mechanisms that characterize disease progression remains unclear. This study involved comprehensively collected biospecimens and longitudinal multi-omics data of 300 COVID-19 patients and 120 healthy controls, including whole genome sequencing (WGS), single-cell RNA sequencing combined with T cell receptor (TCR) and B cell receptor (BCR) sequencing (scRNA(+scTCR/BCR)-seq), bulk BCR and TCR sequencing (bulk TCR/BCR-seq), and cytokine profiling. Clinical data were also collected from hospitalized COVID-19 patients, and HLA typing, laboratory characteristics, and COVID-19 viral genome sequencing were performed during the initial diagnosis. The entire set of biospecimens and multi-omics data generated in this project can be accessed by researchers from the National Biobank of Korea with prior approval. This distribution of largescale multi-omics data of COVID-19 patients can facilitate the understanding of biological crosstalk involved in COVID-19 infection and contribute to the development of potential methodologies for its diagnosis and treatment. [BMB Reports 2022; 55(9): 465-471].