The putative mechanism of lymphopenia in COVID-19 patients

Early lymphopenia as a predictor of COVID-19 outcomes: A multicenter cohort study

Introduction

Lymphopenia is recognized as a biomarker for predicting outcomes in coronavirus disease (COVID-19). However, the optimal timing for its observation remains uncertain. We investigated the association between early lymphopenia and COVID-19 prognosis, as well as the relationship between lymphocyte count trends and disease outcomes.

Methods

We analyzed data from the J-RECOVER study, a multicenter retrospective cohort study in Japan, encompassing patients with COVID-19 between January and September 2020. The patients were categorized into lymphopenia (LP) (<800 cells/μL) and non-lymphopenia (NL) (≥800 cells/μL) groups based on the lymphocyte counts between days 1 and 4 post-onset. They were further divided into "persistent," "recovered," "exacerbated," and "stable" groups based on lymphocyte counts between days 7 and 10. The primary outcome was the in-hospital mortality. The Cox proportional hazard regression was used for the analysis.

Results

Of 995 enrolled patients, 212 patients (21.3%) were classified into the LP group. LP was significantly associated with in-hospital mortality (hazard ratio [HR] 2.32, [95% CI 1.39 to 3.87], p-value 0.001). In both the LP and NL groups, lower lymphocyte counts between 7 and 10 days-categorized as the "persistent" and "exacerbated" groups-was associated with in-hospital mortality (HR 4.65, [95% CI 2.07 to 10.47], p-value <0.001, and HR 5.59, [95% CI 2.24 to 13.97], p-value <0.001, respectively).

Conclusions

Early lymphopenia is predictive of poor prognosis in patients with COVID-19. A declining lymphocyte count trend post-onset further indicates disease deterioration.

Integrated viral and immune monitoring in a prospective COVID-19 cohort from India

In this study, we report on longitudinal kinetics of cellular immune subsets following SARS-CoV-2 infection in a cohort of hospitalized individuals and evaluate the interplay of these profiles with infecting viral variants, humoral immunity including neutralizing responses, vaccination history, and clinical outcomes. A cohort of 121 SARS-CoV-2-infected individuals exhibiting varying disease states were prospectively evaluated for lymphopenic profiles, antiviral humoral responses and infecting viral variants for a period of up to 90 d spanning the period of February 2021 to January 2022 (second and third waves of infection). A total of 51 participants received at least 1 vaccine dose of indigenous vaccines (Covishield or Covaxin) prior to recruitment. When stratified in terms of mortality, B and natural killer cells, in contrast to the T cell compartment, did not recover from nadir levels in nonsurvivors who were largely unvaccinated. No discriminatory signature was identified for nonsurvivors in terms of anti-nucleocapsid or anti-S1-RBD IgG chemiluminescent immunoassay profiles including GenScript S1-RBD assays. Evaluation of sVCAM and sMAdCAM revealed opposing dynamics that correlated with disease severity and convalescence respectively. Viral variant analysis revealed Delta and Omicron variants to comprise the majority of the infections, which reflected national transmission kinetics during the period of recruitment. Our results demonstrate the importance of monitoring circulating biomarkers for convalescence as well as mortality in COVID-19 progression. Delta variants of SARS-CoV-2 clearly demonstrated increased pathogenicity and warrants sustained viral surveillance for re-emergence of these strains. Our findings with respect to vaccination advocate for continued vaccine development and administration of COVID-19 vaccines.

Advancing insights in critical COVID-19: unraveling lymphopenia through propensity score matching - Findings from the Multicenter LYMPH-COVID Study

OBJECTIVE

To elucidate the impact of lymphopenia on critical COVID-19 patient outcomes.

METHODS

We conducted a multicenter prospective cohort study across five hospitals in Portugal and Brazil from 2020 to 2021. The study included adult patients admitted to the intensive care unit with SARS-CoV-2 pneumonia. Patients were categorized into two groups based on their lymphocyte counts within 48 hours of intensive care unit admission: the Lymphopenia Group (lymphocyte serum count < 1 × 109/L) and the Nonlymphopenia Group. Multivariate logistic regression, propensity score matching, Kaplan‒Meier survival curve analysis and Cox proportional hazards regression analysis were used.

RESULTS

A total of 912 patients were enrolled, with 191 (20.9%) in the Nonlymphopenia Group and 721 (79.1%) in the Lymphopenia Group. Lymphopenia patients displayed significantly elevated disease severity indices, including Sequential Organ Failure Assessment and Simplified Acute Physiology Score 3 scores, at intensive care unit admission (p = 0.001 and p < 0.001, respectively). Additionally, they presented heightened requirements for vasopressor support (p = 0.045) and prolonged intensive care unit and in-hospital stays (both p < 0.001). Multivariate logistic regression analysis after propensity score matching revealed a significant contribution of lymphopenia to mortality, with an odds ratio of 1,621 (95%CI: 1,275 - 2,048; p < 0.001). Interaction models revealed an increase of 8% in mortality for each decade of longevity in patients with concomitant lymphopenia. In the subanalysis utilizing three-group stratification, the Severe Lymphopenia Group had the highest mortality rate, not only in direct comparisons but also in Kaplan‒Meier survival analysis (log-rank test p = 0.0048).

CONCLUSION

Lymphopenia in COVID-19 patients is associated with increased disease severity and an increased risk of mortality, underscoring the need for prompt support for critically ill high-risk patients. These findings offer important insights into improving patient care strategies for COVID-19 patients.

Pulmonary Function and Survival 1 Year After Dupilumab Treatment of Acute Moderate to Severe Coronavirus Disease 2019: A Follow-up Study From a Phase 2a Trial

Background

We previously conducted a phase 2a randomized placebo-controlled trial of 40 subjects to assess the efficacy and safety of dupilumab use in people hospitalized with coronavirus disease 2019 (COVID-19) (NCT04920916). Based on our preclinical data suggesting that downstream pulmonary dysfunction with COVID-19 induced type 2 inflammation, we contacted patients from our phase 2a study at 1 year for assessment of post-COVID-19 conditions.

Methods

Subjects at 1 year after treatment underwent pulmonary function tests, high-resolution computed tomographic imaging, symptom questionnaires, neurocognitive assessments, and serum immune biomarker analysis, with subject survival also monitored. The primary outcome was the proportion of abnormal diffusion capacity for carbon monoxide (DLCO) or 6-minute walk test (6MWT) at the 1-year visit.

Results

Of those survivors who consented to 1-year visits (n = 16), subjects who had originally received dupilumab were less likely than those who received placebo to have an abnormal DLCO or 6MWT (Fisher exact P = .011; adjusted P = .058). As a secondary endpoint, we saw that 16% of subjects in the dupilumab group died by 1 year compared to 38% in the placebo group, though this was not statistically significant (log-rank P = .12). We did not find significant differences in neurocognitive testing, symptoms, or chest computed tomography between treatment groups but observed a larger reduction in eotaxin levels in those who received dupilumab.

Conclusions

In this observational study, subjects who received dupilumab during acute COVID-19 hospitalization were less likely to have a reduced DLCO or 6MWT, with a nonsignificant trend toward reduced mortality at 1 year compared to placebo.

Tonsils are major sites of persistence of SARS-CoV-2 in children

In the present study, we show that SARS-CoV-2 can infect palatine tonsils, adenoids, and secretions in children without symptoms of COVID-19, with no history of recent upper airway infection. We studied 48 children undergoing tonsillectomy due to snoring/OSA or recurrent tonsillitis between October 2020 and September 2021. Nasal cytobrushes, nasal washes, and tonsillar tissue fragments obtained at surgery were tested by RT-qPCR, immunohistochemistry (IHC), flow cytometry, and neutralization assay. We detected the presence of SARS-CoV-2 in at least one specimen tested in 27% of patients. IHC revealed the presence of the viral nucleoprotein in epithelial surface and in lymphoid cells in both extrafollicular and follicular regions, in adenoids and palatine tonsils. Also, IHC for the SARS-CoV-2 non-structural protein NSP-16 indicated the presence of viral replication in 53.8% of the SARS-CoV-2-infected tissues. Flow cytometry showed that CD20+ B lymphocytes were the most infected phenotypes, followed by CD4+ lymphocytes and CD123 dendritic cells, CD8+ T lymphocytes, and CD14+ macrophages. Additionally, IF indicated that infected tonsillar tissues had increased expression of ACE2 and TMPRSS2. NGS sequencing demonstrated the presence of different SARS-CoV-2 variants in tonsils from different tissues. SARS-CoV-2 antigen detection was not restricted to tonsils but was also detected in nasal cells from the olfactory region. Palatine tonsils and adenoids are sites of prolonged RNA presence by SARS-CoV-2 in children, even without COVID-19 symptoms. IMPORTANCE This study shows that SRS-CoV-2 of different lineages can infect tonsils and adenoids in one quarter of children undergoing tonsillectomy. These findings bring advancement to the area of SARS-CoV-2 pathogenesis, by showing that tonsils may be sites of prolonged infection, even without evidence of recent COVID-19 symptoms. SARS-CoV-2 infection of B and T lymphocytes, macrophages, and dendritic cells may interfere with the mounting of immune responses in these secondary lymphoid organs. Moreover, the shedding of SARS-CoV-2 RNA in respiratory secretions from silently infected children raises concern about possible diagnostic confusion in the presence of symptoms of acute respiratory infections caused by other etiologies.

Transcriptomic and proteomic assessment of tocilizumab response in a randomized controlled trial of patients hospitalized with COVID-19

High interleukin (IL)-6 levels are associated with greater COVID-19 severity. IL-6 receptor blockade by tocilizumab (anti-IL6R; Actemra) is used globally for the treatment of severe COVID-19, yet a molecular understanding of the therapeutic benefit remains unclear. We characterized the immune profile and identified cellular and molecular pathways modified by tocilizumab in peripheral blood samples from patients enrolled in the COVACTA study, a phase 3, randomized, double-blind, placebo-controlled trial of the efficacy and safety of tocilizumab in hospitalized patients with severe COVID-19. We identified markers of inflammation, lymphopenia, myeloid dysregulation, and organ injury that predict disease severity and clinical outcomes. Proteomic analysis confirmed a pharmacodynamic effect for tocilizumab and identified novel pharmacodynamic biomarkers. Transcriptomic analysis revealed that tocilizumab treatment leads to faster resolution of lymphopenia and myeloid dysregulation associated with severe COVID-19, indicating greater anti-inflammatory activity relative to placebo and potentially leading to faster recovery in patients hospitalized with COVID-19.

Pulmonary function and survival one year after dupilumab treatment of acute moderate to severe COVID-19: A follow up study from a Phase IIa trial

Background

We previously conducted a Phase IIa randomized placebo-controlled trial of 40 subjects to assess the efficacy and safety of dupilumab use in those hospitalized with COVID-19 (NCT04920916). Based on our pre-clinical data suggesting downstream pulmonary dysfunction with COVID-19 induced type 2 inflammation, we contacted patients from our Phase IIa study at 1 year for assessment of Post Covid-19 Conditions (PCC).

Methods

Subjects at 1 year after treatment underwent pulmonary function testing (PFTs), high resolution computed tomography (HRCT) imaging, symptom questionnaires, neurocognitive assessments, and serum immune biomarker analysis, with subject survival also monitored. The primary outcome was the proportion of abnormal PFTs, defined as an abnormal diffusion capacity for carbon monoxide (DLCO) or 6-minute walk testing (6MWT) at the 1-year visit.

Results

Sixteen of the 29 one-year survivors consented to the follow up visit. We found that subjects who had originally received dupilumab were less likely to have abnormal PFTs compared to those who received placebo (Fisher's exact p=0.011, adjusted p=0.058). We additionally found that 3 out of 19 subjects (16%) in the dupilumab group died by 1 year compared to 8 out of 21 subjects (38%) in the placebo group (log rank p=0.12). We did not find significant differences in neurocognitive testing, symptoms or CT chest imaging between treatment groups but observed evidence of reduced type 2 inflammation in those who received dupilumab.

Conclusions

We observed evidence of reduced long-term morbidity and mortality from COVID-19 with dupilumab treatment during acute hospitalization when added to standard of care regimens.