Nikhil Prasad Fact checked by:Thailand Medical News Team Oct 24, 2024 1 day, 15 hours, 23 minutes ago
Medical News: A new study has revealed important insights into how infants respond to COVID-19, highlighting key differences from adults. The research, led by experts from several prestigious institutions, explored the immune responses of infants with varying severity of COVID-19, ranging from mild to severe cases. American researchers from St. Jude Children’s Research Hospital, Nationwide Children's Hospital, and The Jackson Laboratory took part in this groundbreaking investigation.
Infant Immune Responses to COVID-19 Show Key Differences from Adults
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In this
Medical News report, we will delve into the unique aspects of this study and explain how infants' immune responses differ from those seen in adults with COVID-19.
The Study
The researchers focused on infants under one year of age who were hospitalized due to COVID-19, including infants with mild, moderate, and severe cases. Using advanced single-cell RNA sequencing technology, they examined immune cells from the blood samples of 26 infants with COVID-19 and compared them with 14 healthy infant controls. The findings revealed substantial alterations in immune cell compositions and gene activity, particularly in infants with severe cases of COVID-19.
Key Findings
The study found significant differences in the immune responses of infants compared to adults. Infants with severe COVID-19 exhibited a marked increase in immune cell activity, including higher levels of interferon-stimulated genes (ISGs) across various immune cells such as monocytes, T cells, and B cells. These ISGs play a vital role in the body’s defense against viruses, particularly by helping the immune system recognize and eliminate the virus.
Researchers also noted that, unlike in adults, where ISG responses are sometimes delayed or diminished in severe cases, infants showed a robust and early ISG response even in the most severe cases of COVID-19. This strong ISG activation was observed across several immune cell types, including monocytes (a type of white blood cell), T cells (which help coordinate the immune response), and B cells (responsible for antibody production).
One surprising finding was that the immune response in infants was not limited to a specific type of cell. Rather, it affected many different types of immune cells simultaneously. This widespread immune activation in infants contrasts with the more compartmentalized immune response seen in adults.
Monocyte and T Cell Responses
A key part of the study focused on CD14+ monocytes, which are a type of immune cell that typically responds to infection by producing inflammation. In infants with severe COVID-19, these monocytes displayed a unique pattern of gene activity, expressing both inflammatory and interferon-stimulated genes at high levels. This dual gene expression suggests that these cells play a critical role in driving both inflammation and antiviral responses in infants.
In addition, the study revealed that infants with moderate and severe COVID-19 had highe
r levels of ISG-expressing CD4+ and CD8+ T cells. These T cells help coordinate the immune response, and their increased activity in infants may contribute to the heightened immune responses observed in this age group.
Differences Between Infants and Adults
The study compared the immune responses of infants with COVID-19 to previously published data on adults with the virus. One of the most striking differences was the broader expression of ISGs in infants' immune cells compared to adults. While adults with severe COVID-19 often experience a failure to properly activate these ISGs, infants consistently showed a strong ISG response across various immune cells, suggesting that their immune systems are more primed to combat the virus.
Furthermore, the researchers found that infants did not exhibit the same depletion of CD16+ monocytes that is typically seen in adults with severe COVID-19. Instead, infants maintained normal levels of these immune cells, which also showed high levels of ISG activity.
Cytokine Levels
Cytokines, which are signaling proteins that regulate immune responses, were also measured in the infants' blood. The study found increased levels of inflammatory cytokines, particularly in infants with severe COVID-19. These elevated cytokine levels were similar to those observed in adults with severe COVID-19 and are associated with the development of inflammation and tissue damage.
Conclusions
The study highlights several key differences between the immune responses of infants and adults to COVID-19. Infants, even those with severe disease, mount a robust antiviral immune response characterized by widespread activation of ISGs across multiple immune cell types. This response contrasts with the delayed or impaired ISG activation often observed in adults with severe COVID-19.
Additionally, infants did not show the same immune cell depletions that are commonly seen in adults, suggesting that their immune systems may be better equipped to handle the virus in some respects.
Despite these strong immune responses, some infants still develop severe disease, which may be related to other factors such as underlying health conditions or differences in how their immune systems regulate inflammation. The findings underscore the need for further research into how COVID-19 affects infants and children and how their immune systems can be better supported during infection.
The study findings were published on a preprint server and are currently being peer reviewed.
https://www.researchsquare.com/article/rs-5176621/v1
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