Characterization of memory T cell subsets and common γ-chain cytokines in convalescent COVID-19 individuals.

T cells are thought to be an important correlates of protection against SARS-CoV2 infection. However, the composition of T cell subsets in convalescent individuals of SARS-CoV2 infection has not been well studied. The authors determined the lymphocyte absolute counts, the frequency of memory T cell subsets, and the plasma levels of common γ-chain in 7 groups of COVID-19 individuals, based on days since RT-PCR confirmation of SARS-CoV-2 infection. The data show that both absolute counts and frequencies of lymphocytes as well as, the frequencies of CD4+ central and effector memory cells increased, and the frequencies of CD4+ naïve T cells, transitional memory, stem cell memory T cells, and regulatory cells decreased from Days 15-30 to Days 61-90 and plateaued thereafter. In addition, the frequencies of CD8+ central memory, effector, and terminal effector memory T cells increased, and the frequencies of CD8+ naïve cells, transitional memory, and stem cell memory T cells decreased from Days 15-30 to Days 61-90 and plateaued thereafter. The plasma levels of IL-2, IL-7, IL-15, and IL-21-common γc cytokines started decreasing from Days 15-30 till Days 151-180. Severe COVID-19 patients exhibit decreased levels of lymphocyte counts and frequencies, higher frequencies of naïve cells, regulatory T cells, lower frequencies of central memory, effector memory, and stem cell memory, and elevated plasma levels of IL-2, IL-7, IL-15, and IL-21. Finally, there was a significant correlation between memory T cell subsets and common γc cytokines. Thus, the study provides evidence of alterations in lymphocyte counts, memory T cell subset frequencies, and common γ-chain cytokines in convalescent COVID-19 individuals.

Robust SARS-CoV-2-specific T cell immunity is maintained at 6 months following primary infection.

The immune response to SARS-CoV-2 is critical in controlling disease, but there is concern that waning immunity may predispose to reinfection. We analyzed the magnitude and phenotype of the SARS-CoV-2-specific T cell response in 100 donors at 6 months following infection. T cell responses were present by ELISPOT and/or intracellular cytokine staining analysis in all donors and characterized by predominant CD4+ T cell responses with strong interleukin (IL)-2 cytokine expression. Median T cell responses were 50% higher in donors who had experienced a symptomatic infection, indicating that the severity of primary infection establishes a 'set point' for cellular immunity. T cell responses to spike and nucleoprotein/membrane proteins were correlated with peak antibody levels. Furthermore, higher levels of nucleoprotein-specific T cells were associated with preservation of nucleoprotein-specific antibody level although no such correlation was observed in relation to spike-specific responses. In conclusion, our data are reassuring that functional SARS-CoV-2-specific T cell responses are retained at 6 months following infection.

Early Differences in Cytokine Production by Severity of Coronavirus Disease 2019.

Most patients with coronavirus disease 2019 (COVID-19) experience asymptomatic disease or mild symptoms, but some have critical symptoms requiring intensive care. It is important to determine how patients with asymptomatic or mild COVID-19 react to severe acute respiratory syndrome coronavirus 2 infection and suppress virus spread. Innate immunity is important for evasion from the first virus attack, and it may play an important role in the pathogenesis in these patients. We measured serum cytokine levels in 95 patients with COVID-19 during the infection's acute phase and report that significantly higher interleukin 12 and 2 levels were induced in patients with asymptomatic or mild disease than in those with moderate or severe disease, indicating the key roles of these cytokines in the pathogenesis of asymptomatic or mild COVID-19.

The relationship between serum levels of interleukin-2 and IL-8 with circulating microRNA-10b in patients with COVID-19.

BACKGROUND: The role of cytokine storm in the immunopathogenesis of coronavirus disease 2019 (COVID-19) has been implicated. OBJECTIVE: To determine the association of microRNA (miRNA)-10b and serum levels of IL-2 and IL-8 in patients with COVID-19. METHODS: Blood samples were obtained from 33 COVID-19 patients and 29 healthy subjects. After RNA extraction and cDNA synthesis, the transcript level of miR-10b was determined by Real-time PCR. In addition, the serum levels of IL-2 and IL-8 were measured in subjects using ELISA. RESULTS: The patient group comprised of 33 patients with COVID-19 (62.4 ± 3.7 years old), 13 (39%) males and 20 (61%) females. In the control group, 29 subjects (56.6 ± 1.6 years old), 9 (31%) males and 20 (69%) females, were included. The expression of miR-10b was significantly downregulated in the peripheral blood of COVID-19 patients in comparison to the healthy controls (fold change= 0.12, P< 0.0001). The levels of IL-2 (P< 0.001) and IL-8 (P< 0.001) were significantly increased in the serum samples of COVID-19 patients compared to the healthy subjects. The expression level of miR-10b was correlated significantly with the serum levels of IL-2 and IL-8 as well as with the age of patients, ESR and CRP levels. CONCLUSIONS: miR-10b is downregulated in the COVID-19 patients and might result in increased levels of IL-2 and IL-8, hence contributing to cytokine storm.

Differences in Immune Responses between Children and Adults with COVID-19.

Over 85 590 000 individuals have been infected with severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2). Although there have been an increasing number of reports on coronavirus disease 2019 (COVID-19), it is unclear why infected children show milder symptoms than adults. A retrospective case study was performed at two designated hospitals for COVID-19. Patients (56 children and 63 adults) with confirmed SARS-CoV-2 infection and mild pneumonia were randomly enrolled in this study. The median age of the children was 7.0 years, and 51.79% of them were boys. The median age of the adults was 57 years, and 47.62% were men. The most common symptoms were fever, cough, sputum and diarrhoea. There were no significant differences in symptoms between children and adult patients. In terms of immunological indices on admission, adult patients displayed typical leukopenia and markedly higher levels of IL-2, IL-4, and IL-6 than child patients. The elevation of IL-2, IL-4 and IL-6 in adults induced more extensive lung injury. The effective and non-aggressive immune response successfully resisted SARS-CoV-2 invasion and maintained mild symptoms in child patients. The correlation of higher IL-2, IL-4, and IL-6 with the lung injury might be evidence that preventing excessive cytokine production can avoid further lung damage in these patients.

The impact of COVID-19 infection on the cytokine profile of pregnant women: A prospective case-control study.

OBJECTIVE: To compare the levels of various cytokines between pregnant women with confirmed coronavirus disease (COVID-19) infection and pregnant women without any defined risk factor. MATERIALS AND METHODS: Pregnant women with confirmed COVID-19 infection (study group)(n = 90) were prospectively compared to a gestational age-matched control group of pregnant women without any defined risk factors (n = 90). Demographic features, clinical characteristics, laboratory parameters, interferon-gamma (IFN γ), interleukin (IL-2), IL-6, IL-10, and IL-17 levels were compared between the groups. Additionally, a correlation analysis was performed in the study group for the assessment of IFN γ, IL-2, IL-6, IL-10, and IL-17 levels with disease severity and CRP levels. RESULTS: Study group had significantly higher pregnancy complication rate, erythrocyte sedimentation rate, C-reactive protein, procalcitonin, ferritin, D-dimer, lactate dehydrogenase, IFN γ, and IL-6 values (p < 0.05). On the other hand, the control group had significantly higher hemoglobin, leukocyte, platelet, lymphocyte, IL-2, IL-10, and IL-17 values (p < 0.05). Statistically significant differences were found between the groups for IFN γ, IL-2, IL-10, and IL-17 values between the trimesters (p < 0.05). Statistically significant positive correlations were found for IFN γ and IL-6 with disease severity (r = 0.41 and p < 0.001 for IFN γ and r = 0.58 and p < 0.001 for IL-6). On the other hand, a moderate negative correlation for IL-2 and a weak negative correlation for IL-10 were present (r = -0.62 and p < 0.001 for IL-2 and r = -0.19 and p = 0.01 for IL-10). A statistically significant positive moderate correlation was found between IL-6 and CRP (r = 0.40 and p < 0.001) CONCLUSION: COVID-19 infection seems to have an impact on the cytokine profile of pregnant women varying according to pregnancy trimesters and cytokine levels seem to be correlated with disease severity.

An inter-correlated cytokine network identified at the center of cytokine storm predicted COVID-19 prognosis.

The hyper-inflammatory response is thought to be a major cause of acute respiratory distress syndrome (ARDS) in patients with COVID-19. Although multiple cytokines are reportedly associated with disease severity, the key mediators of SARS-CoV-2 induced cytokine storm and their predictive values have not been fully elucidated. The present study analyzed maximal and early (within 10 days after disease onset) concentrations of 12-plex cytokines in plasma. We found consistently elevated plasma levels of IL-6, IL-8 and IL-5 in patients who were deceased compared with those who had mild/moderate or severe disease. The early plasma concentrations of IFN-a and IL-2 positively correlated with the length of the disease course. Moreover, correlation network analysis showed that IL-6, IL-8, and IL-5 located at the center of an inter-correlated cytokine network. These findings suggested that IL-8, IL-6, IL-5 might play central roles in cytokine storms associated with COVID-19 and that the early detection of multiple plasma cytokines might help to predict the prognosis of this disease.

Absent immune response to SARS-CoV-2 in a 3-month recurrence of coronavirus disease 2019 (COVID-19) case.

BACKGROUND: The viral persistence in patients with Coronavirus Disease 2019 (COVID-19) remains to be investigated. METHODS: We investigated the viral loads, therapies, clinical features, and immune responses in a 70-year patient tested positive for SARS-CoV-2 for 3 months. FINDINGS: The patient exhibited the highest prevalence of abnormal indices of clinical features and immune responses at the first admission, including fever (38.3 â„ƒ), decreased lymphocytes (0.83 × 109/L) and serum potassium (3.1 mmol/L), as well as elevated serum creatinine (115 µmol/L), urea (8.6 mmol/L), and C-reactive protein (80 mg/L). By contrast, at the second and the third admission, these indices were all normal. Through three admissions, IL-2 increased from 0.14 pg/mL, 0.69 pg/mL, to 0.91 pg/mL, while IL-6 decreased from 11.78 pg/mL, 1.52 pg/mL, to 0.69 pg/mL, so did IL-10 from 5.13 pg/mL, 1.85 pg/mL, to 1.75 pg/mL. The steady declining trend was also found in TNF-α (1.49, 1.15, and 0.85 pg/mL) and IFN-γ (0.64, 0.42, and 0.27 pg/mL). The threshold cycle values of RT-PCR were 26.1, 30.5, and 23.5 for ORFlab gene, and 26.2, 30.6, and 22.7 for N gene, showing the patient had higher viral loads at the first and the third admission than during the middle term of the disease. The patient also showed substantially improved acute exudative lesions on the chest CT scanning images. CONCLUSIONS: The patient displayed declining immune responses in spite of the viral shedding for 3 months. We inferred the declining immune responses might result from the segregation of the virus from the immune system.

The inhibition of IL-2/IL-2R gives rise to CD8+ T cell and lymphocyte decrease through JAK1-STAT5 in critical patients with COVID-19 pneumonia.

Although most patients with COVID-19 pneumonia have a good prognosis, some patients develop to severe or critical illness, and the mortality of critical cases is up to 61.5%. However, specific molecular information about immune response in critical patients with COVID-19 is poorly understood. A total of 54 patients were enrolled and divided into three groups, among which 34 were common, 14 were severe, and 6 were critical. The constitution of peripheral blood mononuclear cells (PBMC) in patients was analyzed by CyTOF. The profile of cytokines was examined in plasma of patients using luminex. The IL-2 signaling pathway was investigated in the PBMC of patients by qRT-PCR. The count and percentage of lymphocytes were significantly decreased in critical patients compared to common and severe patients with COVID-19 pneumonia. The count of T cells, B cells, and NK cells was remarkably decreased in critical patients compared to normal controls. The percentage of CD8+ T cells was significantly lower in critical patients than that in common and severe patients with COVID-19 pneumonia. The expression of IL-2R, JAK1, and STAT5 decreased in PBMC of common, severe, and critical patients, but IL-2 level was elevated in severe patients and decreased in critical patients with COVID-19 pneumonia. The decrease of CD8+ T cells in critical patients with COVID-19 pneumonia may be related to the IL-2 signaling pathway. The inhibition of IL-2/IL-2R gives rise to CD8+ T cell and lymphocyte decrease through JAK1-STAT5 in critical patients with COVID-19 pneumonia.