Lymphocyte Subset Alteration and Monocyte CD4 Expression Reduction in Patients with Severe COVID-19

CD4 expression on monocytes correlates with recovery from multiple organ dysfunction syndrome and mortality in patients with septic shock

Background

To date, the correlation between CD4 on the monocytes (mCD4) expression and the prognosis of patients with septic shock remains unclear. The purpose of this study was to analyze the expression of mCD4 in these patients and further evaluate whether mCD4 expression correlates with either the recovery from multiple organ dysfunction syndrome (MODS) or mortality.

Methods

The study participants were recruited from a tertiary general hospital in China (Affiliated Dongyang Hospital of Wenzhou Medical University). Sepsis and septic shock were diagnosed based on the diagnostic criteria of Sepsis-3. MODS was defined as a Sequential Organ Failure Assessment score of at least two organ systems ≥2. Persistent MODS was defined as the continual meeting of the MODS criteria when re-evaluated one week after admission (day 7). A logistic regression model was used to test whether mCD4 was an independent prognostic factor for mortality in patients with septic shock. A paired sample rank sum test was used to examine the correlation between mCD4 expression and MODS recovery.

Result

The study recruited 79 patients with septic shock as the study group, 74 patients with sepsis as the disease control group, and 56 volunteers as healthy controls. In the first 24 h after admission (day 1), mCD4 expression was significantly reduced in patients with septic shock compared to healthy controls and patients with sepsis. Moreover, mCD4 expression was an independent prognostic factor for in-hospital and 28 day mortality in patients with septic shock. mCD4 expression did not show significant differences in patients with persistent MODS on day 7 compared to day 1. However, mCD4 expression was significantly higher in patients without persistent MODS on day 7 than on day 1.

Conclusion

mCD4 expression is significantly reduced in patients with septic shock, which is an independent prognostic factor for mortality and closely related to recovery from MODS.

Characterizing the Immature Immunophenotype of Sickle Cell Disease Monocytes

Sickle cell disease (SCD) is marked by episodic vaso-occlusive crisis (VOC). Recurrent VOC creates a pro-inflammatory state that induces phenotypic alterations in innate immune cells. Monocytes are of particular interest to VOC pathophysiology because they are especially malleable to inflammatory signaling. Indeed, inflammatory disease states such as chronic obstructive pulmonary disease (COPD), obesity and atherosclerosis are known to influence monocyte development and alter monocyte subpopulations. In this study, we describe SCD monocyte subsets by performing immunophenotypic flow cytometric, enzymatic, and morphologic analysis on peripheral blood. Herein, we add to the growing body of evidence suggesting aberrant monocyte populations underpin VOC pathophysiology. We found that SCD monocytes possess an immature phenotype as demonstrated by 1) decreased CD4 positivity (p < .01), 2) low α-naphthyl butyrate esterase (ANBE) expression, and 3) naïve morphologic features. We additionally found an increase in CD14+CD16-CD4- monocytes (p < .01), a subset associated with the impaired immune response of post-trauma patients. Interestingly, we also found a large proportion of CD14+CD4-HLA-DR- monocytes which, under normal circumstances, are exclusively found in neonates (p < .01). Finally, we report an increase in nonclassical monocytes (CD14dimCD16+), a subset recently shown to have a critical role in prevention and recovery from VOC.

Circulating myeloid-derived suppressor cells may be a useful biomarker in the follow-up of unvaccinated COVID-19 patients after hospitalization

SARS-CoV-2 infection is the cause of the disease named COVID-19, a major public health challenge worldwide. Differences in the severity, complications and outcomes of the COVID-19 are intriguing and, patients with similar baseline clinical conditions may have very different evolution. Myeloid-derived suppressor cells (MDSCs) have been previously found to be recruited by the SARS-CoV-2 infection and may be a marker of clinical evolution in these patients. We have studied 90 consecutive patients admitted in the hospital before the vaccination program started in the general population, to measure MDSCs and lymphocyte subpopulations at admission and one week after to assess the possible association with unfavorable outcomes (dead or Intensive Care Unit admission). We analyzed MDSCs and lymphocyte subpopulations by flow cytometry. In the 72 patients discharged from the hospital, there were significant decreases in the monocytic and total MDSC populations measured in peripheral blood after one week but, most importantly, the number of MDSCs (total and both monocytic and granulocytic subsets) were much higher in the 18 patients with unfavorable outcome. In conclusion, the number of circulating MDSCs may be a good marker of evolution in the follow-up of unvaccinated patients admitted in the hospital with the diagnosis of COVID-19.

A deep learning model for predicting COVID-19 ARDS in critically ill patients

Background

The coronavirus disease 2019 (COVID-19) is an acute infectious pneumonia caused by a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection previously unknown to humans. However, predictive studies of acute respiratory distress syndrome (ARDS) in patients with COVID-19 are limited. In this study, we attempted to establish predictive models to predict ARDS caused by COVID-19 via a thorough analysis of patients' clinical data and CT images.

Method

The data of included patients were retrospectively collected from the intensive care unit in our hospital from April 2022 to June 2022. The primary outcome was the development of ARDS after ICU admission. We first established two individual predictive models based on extreme gradient boosting (XGBoost) and convolutional neural network (CNN), respectively; then, an integrated model was developed by combining the two individual models. The performance of all the predictive models was evaluated using the area under receiver operating characteristic curve (AUC), confusion matrix, and calibration plot.

Results

A total of 103 critically ill COVID-19 patients were included in this research, of which 23 patients (22.3%) developed ARDS after admission; five predictive variables were selected and further used to establish the machine learning models, and the XGBoost model yielded the most accurate predictions with the highest AUC (0.94, 95% CI: 0.91-0.96). The AUC of the CT-based convolutional neural network predictive model and the integrated model was 0.96 (95% CI: 0.93-0.98) and 0.97 (95% CI: 0.95-0.99), respectively.

Conclusion

An integrated deep learning model could be used to predict COVID-19 ARDS in critically ill patients.

A burns and COVID-19 shared stress responding gene network deciphers CD1C-CD141- DCs as the key cellular components in septic prognosis

Differential body responses to various stresses, infectious or noninfectious, govern clinical outcomes ranging from asymptoma to death. However, the common molecular and cellular nature of the stress responsome across different stimuli is not described. In this study, we compared the expression behaviors between burns and COVID-19 infection by choosing the transcriptome of peripheral blood from related patients as the analytic target since the blood cells reflect the systemic landscape of immune status. To this end, we identified an immune co-stimulator (CD86)-centered network, named stress-response core (SRC), which was robustly co-expressed in burns and COVID-19. The enhancement of SRC genes (SRCs) expression indicated favorable prognosis and less severity in both conditions. An independent whole blood single-cell RNA sequencing of COVID-19 patients demonstrated that the monocyte-dendritic cell (Mono-DC) wing was the major cellular source of SRC, among which the higher expression of the SRCs in the monocyte was associated with the asymptomatic COVID-19 patients, while the quantity-restricted and function-defected CD1C-CD141-DCs were recognized as the key signature which linked to bad consequences. Specifically, the proportion of the CD1C-CD141-DCs and their SRCs expression were step-wise reduced along with worse clinic conditions while the subcluster of CD1C-CD141-DCs from the critical COVID-19 patients was characterized of IFN signaling quiescence, high mitochondrial metabolism and immune-communication inactivation. Thus, our study identified an expression-synchronized and function-focused gene network in Mono-DC population whose expression status was prognosis-related and might serve as a new target of diagnosis and therapy.

Hepatoprotective and nephroprotective effects of Sedum adenotrichum in paracetamol-induced hepatotoxicity in rabbits

Sedum adenotrichum (SA) has been traditionally used against various ailments due to the presence of several important phenolic compounds. This study provides a scientific basis for the hepatoprotective and nephroprotective potentials of Sedum adenotrichum in paracetamol-induced toxicity in rabbits. Methanolic extract of Sedum adenotrichum along with paracetamol was administered orally to rabbits alone or in combination with paracetamol for 2 weeks. Results showed that paracetamol-induced toxicity was correlated with a significant change in biochemical, hematological parameters, and loss in body weight of rabbits, and the curative effect of SA methanolic extract was found. Liver and kidney histological studies showed significant induced toxicity of paracetamol and correspondence restoration power of SA methanolic extract. The levels of reduced glutathione, radical scavenging activity, and lipid peroxidation in the liver were restored to normal by the methanolic extract of SA. This study confirmed the protective effect of SA methanolic extract against hepatotoxicity and nephrotoxicity caused by paracetamol. Biochemical analysis of the methanolic extract of SA confirmed the presence of bioactive phenolic compounds which have hepatic and nephroprotective potentials.

Peripheral Blood Genes Crosstalk between COVID-19 and Sepsis

Severe coronavirus disease 2019 (COVID-19) has led to a rapid increase in death rates all over the world. Sepsis is a life-threatening disease associated with a dysregulated host immune response. It has been shown that COVID-19 shares many similarities with sepsis in many aspects. However, the molecular mechanisms underlying sepsis and COVID-19 are not well understood. The aim of this study was to identify common transcriptional signatures, regulators, and pathways between COVID-19 and sepsis, which may provide a new direction for the treatment of COVID-19 and sepsis. First, COVID-19 blood gene expression profile (GSE179850) data and sepsis blood expression profile (GSE134347) data were obtained from GEO. Then, we intersected the differentially expressed genes (DEG) from these two datasets to obtain common DEGs. Finally, the common DEGs were used for functional enrichment analysis, transcription factor and miRNA prediction, pathway analysis, and candidate drug analysis. A total of 307 common DEGs were identified between the sepsis and COVID-19 datasets. Protein-protein interactions (PPIs) were constructed using the STRING database. Subsequently, hub genes were identified based on PPI networks. In addition, we performed GO functional analysis and KEGG pathway analysis of common DEGs, and found a common association between sepsis and COVID-19. Finally, we identified transcription factor-gene interaction, DEGs-miRNA co-regulatory networks, and protein-drug interaction, respectively. Through ROC analysis, we identified 10 central hub genes as potential biomarkers. In this study, we identified SARS-CoV-2 infection as a high risk factor for sepsis. Our study may provide a potential therapeutic direction for the treatment of COVID-19 patients suffering from sepsis.

The Association of Low CD4 Expression on Monocytes and Low CD8+ T-Cell Count at Hospital Admission Predicts the Need for Mechanical Ventilation in Patients With COVID-19 Pneumonia: A Prospective Monocentric Cohort Study

To identify COVID-19-associated immunophenotyping patterns at hospital admission and to determine if some patterns could predict the need for mechanical ventilation (MV).

DESIGN

Prospective observational monocentric cohort study.

SETTING

A university-affiliated hospital in Marseille, France.

PATIENTS

Thirty patients presenting with laboratory-confirmed COVID-19 pneumonia were enrolled within the first 48 hours of hospital admission and compared with 18 healthy controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Whole-blood leukocytes were immunophenotyped with a rapid and simplified one-step flow cytometry method. Thirty-eight immune and five laboratory parameters were compared first between COVID-19 patients and controls and then between the COVID-19 patients who received or not MV during their stays. The variables that significantly discriminated MV from non-MV patients in univariate analysis were entered into a multiple stepwise logistic regression analysis. The COVID-19 patients were predominantly male (87%), aged 61 years (50-71 yr), and 93% received early corticosteroid therapy. Sixteen patients (53%) were managed with noninvasive respiratory support, and 14 (47%) required MV. Compared with controls, COVID-19 patients were characterized by an immune signature featuring: 1) decreased HLA-DR expression on monocytes; 2) reduced basophils, eosinophils, T-cells, NK cells, and nonclassical monocyte count; and 3) up regulation of CD169 on monocytes, CD64 on neutrophils, the adhesion/migration markers (CD62L and CD11b), and the checkpoint inhibitor CD274 on myeloid cells. Among the COVID-19 patients, those who received MV had lower level of CD4 and HLA-DR on monocytes, lower CD8+ T-cell count, and higher lactate dehydrogenase at hospital admission. In multivariate analysis, only CD4 on monocytes (p = 0.032) and CD8+ T-cell count (p = 0.026) were associated with MV requirement. The model combining these two variables provided an area under curve of 0.97 (95% CI, 0.83-0.99).

CONCLUSIONS

The association of low CD4 on monocytes and low CD8+ T-cell count at hospital admission was highly predictive of the need for MV in hospitalized patients with COVID-19 pneumonia.

Validation of the T-Lymphocyte Subset Index (TLSI) as a Score to Predict Mortality in Unvaccinated Hospitalized COVID-19 Patients

Lymphopenia has been consistently reported as associated with severe coronavirus disease 2019 (COVID-19). Several studies have described a profound decline in all T-cell subtypes in hospitalized patients with severe and critical COVID-19. The aim of this study was to assess the role of T-lymphocyte subset absolute counts measured at ward admission in predicting 30-day mortality in COVID-19 hospitalized patients, validating a new prognostic score, the T-Lymphocyte Subset Index (TLSI, range 0−2), based on the number of T-cell subset (CD4+ and CD8+) absolute counts that are below prespecified cutoffs. These cutoff values derive from a previously published work of our research group at Policlinico Tor Vergata, Rome, Italy: CD3+CD4+ < 369 cells/μL, CD3+CD8+ < 194 cells/μL. In the present single-center retrospective study, T-cell subsets were assessed on admission to the infectious diseases ward. Statistical analysis was performed using JASP (Version 0.16.2. JASP Team, 2022, Amsterdam, The Netherlands) and Prism8 (version 8.2.1. GraphPad Software, San Diego, CA, USA). Clinical and laboratory parameters of 296 adult patients hospitalized because of COVID-19 were analyzed. The overall mortality rate was 22.3% (66/296). Survivors (S) had a statistically significant lower TLSI score compared to non-survivors (NS) (p < 0.001). Patients with increasing TLSI scores had proportionally higher rates of 30-day mortality (p < 0.0001). In the multivariable logistic analysis, the TLSI was an independent predictor of in-hospital 30-day mortality (OR: 1.893, p = 0.003). Survival analysis showed that patients with a TLSI > 0 had an increased risk of death compared to patients with a TLSI = 0 (hazard ratio: 2.83, p < 0.0001). The TLSI was confirmed as an early and independent predictor of COVID-19 in-hospital 30-day mortality.

Diagnostic Value of Natural Killer Cells, CD56+ CD16+ Natural Killer Cells, NLRP3, and Lactate Dehydrogenase in Severe/Critical COVID-19: A Prospective Longitudinal Study According to the Severe/Critical COVID-19 Definitions

Innate immunity, as the first line of defense of our immune system, plays a crucial role in defending against SARS-CoV-2 infection and also its immunopathogenesis. We aim to investigate the immune status of natural killer (NK) cells, natural killer T (NKT) cells, and NLRP3 gene expression in COVID-19 patient blood samples. The immunophenotype of NK cell subsets and NKT cells was detected by flow cytometry and the expression of NLRP3 gene assessed by reverse transcriptase real-time polymerase chain reaction in 44 COVID-19 patients and 20 healthy individuals. The percentage of most of NK cell subpopulation and NKT cells was significantly decreased in COVID-19 patients. The percentage of CD56dim CD16- NK cell subsets, and NLRP3 gene expression increased. The percentage of total NK cells, CD56+ CD16+ NK cells, and NLRP3 gene expression had acceptable sensitivity and specificity for assisting diagnosis of severe/critical COVID-19. O₂ saturation% and lactate dehydrogenase levels showed valuable diagnostic value to identify critical cases. The declined NK and NKT cells in COVID-19 patients and enhanced NLRP3 gene expression were associated with disease severity. Total NK cells, CD56+ CD16+ NK cells, and NLRP3 gene expression might be used as meaningful indicators for assisting diagnosis of severe/critical COVID-19.

Identification of lymphocyte subgroups with flow cytometry in COVID-19 patients

Objective: We aimed to determine lymphocyte subgroups and activation status of flow cytometry in COVID-19 patients and examine their relationship with disease stage and length of hospital stay. Material and Method: Forty patients were analyzed in this study and compared with the age and sex-matched 40 healthy controls. COVID-19 patients have split as early and advanced-stage diseases. Flow cytometry assay was performed to determine the counts of lymphocyte subsets and activation status. Total lymphocyte count was calculated and CD45 (cluster of differentiation), CD3, CD4, CD8, CD19, CD27, CD38, CD56, CD57, and IgD were studied on lymphocyte gate. T helper / T cytotoxic rates and length of hospital stay were recorded. Results: The patients' CD3(+)CD4(+) ( T helper) count and CD27 expression on T cells counts were significantly lower, and CD57 expression on CD3(+)CD8(+) T cytotoxic cells were significantly higher (p

Immune Cells Profiles In The Peripheral Blood Of Patients With Moderate To Severe COVID-19 And Healthy Subjects With and Without Vaccination With The Pfizer-BioNTech mRNA Vaccine

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus disease 2019 (COVID-19), has caused a global crisis. Patients with COVID-19 present with a range of clinical manifestations, from no symptoms to severe illness. However, little is known about the profiles of immune cells required to protect against SARS-CoV-2. This study was performed to determine the immune cells profiles in the peripheral blood of COVID-19 patients with moderate to severe disease (n=52), and compare the findings with those from healthy subjects vaccinated with Pfizer BioNTech mRNA vaccine (VS) (n=62), and non-vaccinated healthy subjects (HS) (n=30) from Kuwait. Absolute counts and percentages of total lymphocytes and lymphocyte subsets (CD3+ T cells, CD4+ T cells, CD8+ T cells, CD19+ B cells, and CD16+CD56+ NK cells) in the peripheral blood of the three groups were analyzed using flow cytometry. The results showed that the absolute counts of total lymphocytes, CD3+, CD4+, and CD8+ T cells, CD19+ B cells, and CD56+ NK cells, were significantly lower in COVID-19 patients than normal healthy controls and vaccinated subjects. The percentages of CD3+ and CD4+ T lymphocytes were also significantly lower in the COVID-19 patients. However, the percentage of CD16+CD56+ NK cells was significantly higher in the peripheral blood of COVID-19 patients, compared to the HS and VS groups with no detectable differences in the percentages of CD8+ T cells and CD19+ B cells between the three groups. Analysis of the monocyte subsets has showed a significantly higher percentage of CD14+HLA-DR+ monocytes in COVID-19 patients compared to HS whereas the inflammatory CD14+CD16+ HLA-DR+ monocytes, and the non-classical CD16+HLA-DR+ monocytes showed significantly lower frequency in the blood of the patients than that of HS. These findings demonstrate perturbations of both innate and adaptive immune cell subsets that reflect dysregulated host responses in COVID-19 patients with moderate to severe disease.

Nitrogen dioxide pollution increases vulnerability to COVID-19 through altered immune function

Previous ecological studies suggest the existence of possible interplays between the exposure to air pollutants and SARS-CoV-2 infection. Confirmations at individual level, however, are lacking. To explore the relationships between previous exposure to particulate matter < 10 μm (PM₁₀) and nitrogen dioxide (NO₂), the clinical outcome following hospital admittance, and lymphocyte subsets in COVID-19 patients with pneumonia. In 147 geocoded patients, we assessed the individual exposure to PM₁₀ and NO₂ in the 2 weeks before hospital admittance. We divided subjects according to the clinical outcome (i.e., discharge at home vs in-hospital death), and explored the lymphocyte-related immune function as an index possibly affecting individual vulnerability to the infection. As compared with discharged subjects, patients who underwent in-hospital death presented neutrophilia, lymphopenia, lower number of T CD45, CD3, CD4, CD16/56 + CD3 + , and B CD19 + cells, and higher previous exposure to NO₂, but not PM₁₀. Age and previous NO₂ exposure were independent predictors for mortality. NO₂ concentrations were also negatively related with the number of CD45, CD3, and CD4 cells. Previous NO₂ exposure is a co-factor independently affecting the mortality risk in infected individuals, through negative immune effects. Lymphopenia and altered lymphocyte subsets might precede viral infection due to nonmodifiable (i.e., age) and external (i.e., air pollution) factors. Thus, decreasing the burden of air pollutants should be a valuable primary prevention measure to reduce individual susceptibility to SARS-CoV-2 infection and mortality.

Increased Expression of Tim-3 Is Associated With Depletion of NKT Cells In SARS-CoV-2 Infection

In the ongoing coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), natural killer T (NKT) cells act as primary initiators of immune responses. However, a decrease of circulating NKT cells has been observed in COVID-19 different stages, of which the underlying mechanism remains to be elucidated. Here, by performing single-cell RNA sequencing analysis in three large cohorts of COVID-19 patients, we found that increased expression of Tim-3 promotes depletion of NKT cells during the progression stage of COVID-19, which is associated with disease severity and outcome of patients with COVID-19. Tim-3+ NKT cells also expressed high levels of CD147 and CD26, which are potential SARS-CoV-2 spike binding receptors. In the study, Tim-3+ NKT cells showed high enrichment of apoptosis, higher expression levels of mitochondrial genes and caspase genes, with a larger pseudo time value. In addition, Tim-3+ NKT cells in COVID-19 presented a stronger capacity to secrete IFN-γ, IL-4 and IL-10 compared with healthy individuals, they also demonstrated high expression of co-inhibitory receptors such as PD-1, CTLA-4, and LAG-3. Moreover, we found that IL-12 secreted by dendritic cells (DCs) was positively correlated with up-regulated expression of Tim-3 in NKT cells in COVID-19 patients. Overall, this study describes a novel mechanism by which up-regulated Tim-3 expression induced the depletion and dysfunction of NKT cells in COVID-19 patients. These findings not only have possible implications for the prediction of severity and prognosis in COVID-19 but also provide a link between NKT cells and future new therapeutic strategies in SARS-CoV-2 infection.

Pathological effects of SARS-CoV-2 on hematological and immunological cells: Alterations in count, morphology, and function

The novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19 outbreak, spread rapidly and infected more than 140 million people with more than three million victims worldwide. The SARS-CoV-2 causes destructive changes in the immunological and hematological system of the host. These alterations appear to play a critical role in disease pathology and the emerging of clinical manifestations. In this review, we aimed to discuss the effect of COVID-19 on the count, function and morphology of immune and blood cells and the role of these changes in the pathophysiology of the disease. Knowledge of these changes may help with better management and treatment of COVID-19 patients.

Reduced Monocyte Subsets, Their HLA-DR Expressions, and Relations to Acute Phase Reactants in Severe COVID-19 Cases

Monocytes are one of the principal immune defense cells that encounter infectious agents. However, an essential role of monocytes has been shown in the spread of viruses throughout the human body. Considering this dilemma, this study aimed to evaluate monocyte subsets and Human Leukocyte Antigen-DR isotype (HLA-DR) expressions in clinical coronavirus disease 2019 (COVID-19) cases. This prospective, multicenter, case-control study was conducted with COVID-19 patients and healthy controls. The patient group was divided into two subgroups according to disease severity (severe and non-severe). Three monocyte subsets (classical, CL; intermediate, INT; non-classical, NC) were analyzed with flow cytometry upon the patients' hospital admission. A total of 42 patients with COVID-19 and 30 controls participated in this study. The patients' conditions were either severe (n = 23) or non-severe (n = 19). All patients' monocyte and HLA-DR expressions were decreased compared with the controls (p < 0.05). Per disease severity, all monocyte subsets were not significant with disease severity; however, the HLA-DR expressions of CL monocytes (p = 0.002) and INT monocytes (p = 0.025) were more decreased in the severe patient group. In patients with various clinical features, NC monocytes were more affected. Based on these results, NC monocytes were more decreased in acute COVID-19 cases, though related various clinics decreased all monocyte subsets in these patients. Decreased monocyte HLA expressions may be a sign of immune suppression in severe patients, even when the percentage of monocyte levels has not decreased yet.

Novel Systemic Inflammation Markers to Predict COVID-19 Prognosis

Coronavirus disease 2019 (COVID-19) has resulted in a global pandemic, challenging both the medical and scientific community for the development of novel vaccines and a greater understanding of the effects of the SARS-CoV-2 virus. COVID-19 has been associated with a pronounced and out-of-control inflammatory response. Studies have sought to understand the effects of inflammatory response markers to prognosticate the disease. Herein, we aimed to review the evidence of 11 groups of systemic inflammatory markers for risk-stratifying patients and prognosticating outcomes related to COVID-19. Numerous studies have demonstrated the effectiveness of neutrophil to lymphocyte ratio (NLR) in prognosticating patient outcomes, including but not limited to severe disease, hospitalization, intensive care unit (ICU) admission, intubation, and death. A few markers outperformed NLR in predicting outcomes, including 1) systemic immune-inflammation index (SII), 2) prognostic nutritional index (PNI), 3) C-reactive protein (CRP) to albumin ratio (CAR) and high-sensitivity CAR (hsCAR), and 4) CRP to prealbumin ratio (CPAR) and high-sensitivity CPAR (hsCPAR). However, there are a limited number of studies comparing NLR with these markers, and such conclusions require larger validation studies. Overall, the evidence suggests that most of the studied markers are able to predict COVID-19 prognosis, however NLR seems to be the most robust marker.

Myeloid cells in COVID-19 microenvironment

Varying differentiation of myeloid cells is common in tumors, inflammation, autoimmune diseases, and metabolic diseases. The release of cytokines from myeloid cells is an important driving factor that leads to severe COVID-19 cases and subsequent death. This review briefly summarizes the results of single-cell sequencing of peripheral blood, lung tissue, and cerebrospinal fluid of COVID-19 patients and describes the differentiation trajectory of myeloid cells in patients. Moreover, we describe the function and mechanism of abnormal differentiation of myeloid cells to promote disease progression. Targeting myeloid cell-derived cytokines or checkpoints is essential in developing a combined therapeutic strategy for patients with severe COVID-19.

Clinical Trials of COVID-19 Therapies Should Account for Diabetes and Hyperglycemia

Complications of Coronavirus Disease 2019 (COVID-19) occur with increased frequency in people admitted to the hospital with diabetes or hyperglycemia. The increased risk for COVID-19 infections in the presence of these metabolic conditions is in part due to overlapping pathophysiologic features of COVID-19, diabetes, and glucose control. Various antiviral treatments are being tested in COVID-19 patients. We believe that in these trials, it will be useful to evaluate treatment effect differences in patients stratified according to whether they have diabetes or hyperglycemia. In this way, it will be possible to better facilitate development of antiviral treatments that are most specifically beneficial for the large subset of COVID-19 patients who have diabetes or hyperglycemia.

Transcriptional Changes in CD16+ Monocytes May Contribute to the Pathogenesis of COVID-19

The COVID-19 pandemic has caused more than three million deaths globally. The severity of the disease is characterized, in part, by a dysregulated immune response. CD16+ monocytes are innate immune cells involved in inflammatory responses to viral infections, and tissue repair, among other functions. We characterized the transcriptional changes in CD16+ monocytes from PBMC of people with COVID-19, and from healthy individuals using publicly available single cell RNA sequencing data. CD16+ monocytes from people with COVID-19 compared to those from healthy individuals expressed transcriptional changes indicative of increased cell activation, and induction of a migratory phenotype. We also analyzed COVID-19 cases based on severity of the disease and found that mild cases were characterized by upregulation of interferon response and MHC class II related genes, whereas the severe cases had dysregulated expression of mitochondrial and antigen presentation genes, and upregulated inflammatory, cell movement, and apoptotic gene signatures. These results suggest that CD16+ monocytes in people with COVID-19 contribute to a dysregulated host response characterized by decreased antigen presentation, and an elevated inflammatory response with increased monocytic infiltration into tissues. Our results show that there are transcriptomic changes in CD16+ monocytes that may impact the functions of these cells, contributing to the pathogenesis and severity of COVID-19.

The effect of cell isolation methods on the human transcriptome profiling and microbial transcripts of peripheral blood

The expression of human and microbial genes serves as biomarkers for disease and health. Blood RNA is an important biological resource for precision medicine and translational medicine. However, few studies have assessed the human transcriptome profiles and microbial communities composition and diversity of peripheral blood from different cell isolation methods, which could affect the reproducibility of researches. We collected peripheral blood from three healthy donors and processed it immediately. We used RNA sequencing to investigate the effect of three leukocyte isolation methods including buffy coat (BC) extraction, red blood cell (RBC) lysis and peripheral blood mononuclear cell (PBMC) isolation with the comparison with whole blood (WB), through analyzing the sensitivity of gene detection, the whole transcriptome profiling and microbial composition and diversity. Our data showed that BC extraction with high globin mRNA mapping rate had similar transcriptome profiles with WB, while RBC lysis and PBMC isolation depleted RBCs effectively. With the efficient depletion of RBC and distinct compositions of leukocyte subsets, RNA-seq of RBC lysis and PBMC isolation uniquely detected genes from specific cell types, like granulocytes and NK cells. In addition, we observed that the microbial composition and diversity were more affected by individuals than isolation methods. Our results showed that blood cell isolations could largely influence the sensitivity of detection of human genes and transcriptome profile.

Assessment of Galectin-1, Galectin-3, and PGE2 Levels in Patients with COVID-19

It is important to determine the inflammatory biomarkers in the severity of Coronavirus Disease 2019 (COVID-19) with the emergence of the pandemic. Galectins and prostaglandins play important roles in the regulation of immune and inflammatory responses. Therefore, this study aimed to investigate Galectin-1 (Gal-1), Galectin-3 (Gal-3), and prostaglandin E2 (PGE2) levels in patients with COVID-19. Gal-1, Gal-3, and PGE2 serum concentrations were measured using enzyme-linked immunosorbent analysis (ELISA) on 84 COVID-19 patients (severe=29 and nonsevere=55) and 56 healthy controls. In this study, the increased levels of Gal-1 (median, 9.86, 6.35, 3.67 ng/ml), Gal-3 (median, 415.31, 326.33, 243.13 pg/ml)and PGE2 (median, 193.17, 192.58, 124.62 pg/ml) levels were found in patients with COVID-19 than healthy controls (p<0.001 for all). In the severe group, Gal-3 levels were higher while there were no differences in Gal-1 and PGE2 levels (p=0.011, p=0.263, p=0.921, respectively). There was a positive correlation between serum Gal-1 and Gal-3 levels (ρ=0.871, p<0.001). Gal-3, C-reactive protein, lymphocyte count, and age were found as independent predictors of the disease severity (p=0.002, p=0.001, p=0.007, and p=0.003, respectively). With the emergence of effective drug needs in the COVID-19 pandemic, differentiation of severe disease is important. Gal-3 could be a potential prognostic biomarker of COVID-19.

Endothelium Infection and Dysregulation by SARS-CoV-2: Evidence and Caveats in COVID-19

The ongoing pandemic of coronavirus disease 2019 (COVID-19) caused by the acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) poses a persistent threat to global public health. Although primarily a respiratory illness, extrapulmonary manifestations of COVID-19 include gastrointestinal, cardiovascular, renal and neurological diseases. Recent studies suggest that dysfunction of the endothelium during COVID-19 may exacerbate these deleterious events by inciting inflammatory and microvascular thrombotic processes. Although controversial, there is evidence that SARS-CoV-2 may infect endothelial cells by binding to the angiotensin-converting enzyme 2 (ACE2) cellular receptor using the viral Spike protein. In this review, we explore current insights into the relationship between SARS-CoV-2 infection, endothelial dysfunction due to ACE2 downregulation, and deleterious pulmonary and extra-pulmonary immunothrombotic complications in severe COVID-19. We also discuss preclinical and clinical development of therapeutic agents targeting SARS-CoV-2-mediated endothelial dysfunction. Finally, we present evidence of SARS-CoV-2 replication in primary human lung and cardiac microvascular endothelial cells. Accordingly, in striving to understand the parameters that lead to severe disease in COVID-19 patients, it is important to consider how direct infection of endothelial cells by SARS-CoV-2 may contribute to this process.