Distinct Mitochondria-Mediated T-Cell Apoptosis Responses in Children and Adults With Coronavirus Disease 2019.

BACKGROUND: Lymphopenia is a key feature for adult patients with coronavirus disease 2019 (COVID-19), although it is rarely observed in children. The underlying mechanism remains unclear. METHODS: Immunohistochemical and flow cytometric analyses were used to compare the apoptotic rate of T cells from COVID-19 adults and children and apoptotic responses of adult and child T cells to COVID-19 pooled plasma. Biological properties of caspases and reactive oxygen species were assessed in T cells treated by COVID-19 pooled plasma. RESULTS: Mitochondria apoptosis of peripheral T cells were identified in COVID-19 adult patient samples but not in the children. Furthermore, increased tumor necrosis factor-α and interleukin-6 in COVID-19 plasma induced mitochondria apoptosis and caused deoxyribonucleic acid damage by elevating reactive oxygen species levels of the adult T cells. However, the child T cells showed tolerance to mitochondrial apoptosis due to mitochondria autophagy. Activation of autophagy could decrease apoptotic sensitivity of the adult T cells to plasma from COVID-19 patients. CONCLUSIONS: Our results indicated that the mitochondrial apoptosis pathway was activated in T cells of COVID-19 adult patients specifically, which may shed light on the pathophysiological difference between adults and children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 ).

Association of Early Inflammation with Age and Asymptomatic Disease in COVID-19.

BACKGROUND: Disease severity in COVID-19 ranges from asymptomatic infection to severe disease and death, especially in older subjects. The risk for severe infection and death has been reported to be 2X in those between 30 and 40 years, 3X in those between 40 and 50 years, and 4X in those between 50 and 65 years, compared to the reference group of 18-29 years. OBJECTIVE: To investigate the early changes in host immune responses that are altered with age and the difference in the early host inflammatory response that dictates a symptomatic versus asymptomatic course of COVID-19. PATIENTS AND METHODS: COVID-19 subjects were identified by screening at the airport upon arrival from a foreign destination to China. Patients were either asymptomatic or had a mild disease when the first oro-pharyngeal (OP) swab samples were collected. Patients were quarantined and blood and throat swabs were collected during the course of the disease, allowing identification of the earliest host response to COVID-19. These patients were followed until their OP sample turned COVID-19 negative. RESULTS: Data were obtained from 126 PCR-confirmed COVID-19 patients. The blood samples were obtained within 48 days of qPCR confirmation of viral infection. Older subjects (>30 years) had significantly elevated levels of anti-inflammatory cytokine IL-10, a significant decrease in the percentage of CD8+ T cells, and expansion in NKT cell fraction. This was associated with significantly elevated viral load and a delayed humoral response in older subjects. Compared to symptomatic subjects, asymptomatic patients had an early increase in pro-inflammatory cytokine IL-2, while a decrease in both T regulatory cells and anti-inflammatory cytokine IL-10. Further, asymptomatic disease was associated with early humoral response and faster viral clearance. CONCLUSION: Early inflammatory response potentially plays a critical role for host-defense in COVID-19. The impaired early inflammatory response was associated with older age while a robust early inflammation was associated with asymptomatic disease.

[Prevention and control of SARS-CoV-2 infection in clinical laboratories: implementation of contingency plan and postpandemic response strategies].

The outbreak of COVID-19 has currently been under control in China, but now the disease has rapidly evolved into a global pandemic. We formulated a prevention and control plan for clinical laboratories responsible for detection of the novel coronavirus infection. We analyzed the implementation of this plan and the problems arising from its clinical practice. We found that the layout of most clinical laboratories (including gene amplification laboratories for clinical samples) was inadequate in response to a major outbreak and did not meet the requirements for biosafety protection and etiology and serology testing; and laboratory staff showed insufficiencies in their awareness regarding biosafety protection; the functions and status of the laboratory in the fever clinic need to be enhanced to increase its detection capacity; the high density of military personnel, the low level of automation of clinical laboratory equipment, and the lack of biosafety cabinets and personal protective equipment all limit the performance of diverse military operations and major overseas missions. In view of these problems, we propose the following strategies and recommendations: the clinical laboratory needs to standardize the design and staff management according to the standards of P2 laboratory; the detection capacity and staffing of fever clinic laboratory in hospitals need to be strengthened, and a separate clinical gene amplification laboratory can be optimal; for those clinical gene amplification laboratories that fail to meet these standards, reconstruction and upgrade should be made according to the requirements of biosafety protection; for the clinical laboratory in the military medical system, in addition to enforcement of biological safety protection of the staff, sufficient supply of medical materials and biological safety equipment should be ensured and biological safety cabinets should be routinely equipped if possible.

[Application of laboratory diagnostic technologies for SARS-CoV-2: current progress and prospect].

Since the outbreak of COVID-19 pandemic, the detection capability has been improving and the detection techniques have been evolving with innovations. qRT- PCR and mNGS, which represent the current mainstay diagnostic technologies, play key roles in disease diagnosis and monitoring of virus variation. The detection technologies based on serum and plasma IgM and IgG antibodies are important for auxiliary diagnosis. RT-LAMP is highly specific for a diagnostic purpose. Digital PCR could quantitatively detect nucleic acid and SHERLOCK has a higher sensitivity. These techniques all have great potential for future development and application for pathogen detection. In this review the authors summarize the basic rationales, technical characteristics and the current application of the SARS-CoV-2 detection techniques.