COVID-19 News: Study Finds Critical Modifications To Key Components Of The Immune System For Up To Six Months As A Result Of SARS-CoV-2 Hospitalization!

COVID-19 News: A new study by Swedish researchers from Linköping University - Sweden and Ryhov County Hospital, Jönköping – Sweden has that SARS-CoV-2 infections especially in those that were hospitalized, caused major alterations to key components of the immune system such as the monocytes and dendritic cells for up to six months after recovery!


 
According to the study team, after more than two years the COVID-19 pandemic continues to burden healthcare systems and economies worldwide, and it is evident that the effects on the immune system can persist for months post-infection.
 
The activity of myeloid cells such as monocytes and dendritic cells (DC) is essential for correct mobilization of the innate and adaptive responses to a pathogen. Impaired levels and responses of monocytes and DC to the SARS-CoV-2 virus is likely to be a driving force behind the immune dysregulation that characterizes severe COVID-19.
 
The study team followed a cohort of COVID-19 patients hospitalized during the early waves of the pandemic for 6-7 months. The levels and phenotypes of circulating monocyte and DC subsets were assessed to determine both the early and long-term effects of the SARS-CoV-2 infection.
 
Th study team found increased monocyte levels that persisted for 6-7 months, mostly attributed to elevated levels of classical monocytes. Myeloid derived suppressor cells were also elevated over this period. While in most DC subsets recovered from an initial decrease, the study team found elevated levels of cDC2/cDC3 at the 6-7 months timepoint.
 
Detailed analysis of functional markers on monocytes and DC revealed sustained reduction in program death ligand 1 (PD-L1) expression but increased CD86 expression across almost all cell types examined.
 
It was also found that C-reactive protein (CRP) correlated positively to the levels of intermediate monocytes and negatively to the recovery of DC subsets.
 
The study team concluded that by exploring the myeloid compartments, it was found that alterations in the immune landscape remain more than 6 months after severe COVID-19, which could be indicative of ongoing healing and/or persistence of viral antigens.
 
The study findings were published in the peer reviewed journal: Frontiers in Immunology.
https://www.frontiersin.org/articles/10.3389/fimmu.2022.1082912/full
 
In our previous COVID-19 News coverages, we had also detailed studies that showed the SARS-CoV-2 affecting monocytes and dendritic cells.

https://www.thailandmedical.news/news/covid-19-news-imperial-college-london-study-shows-that-sars-cov-2-causes-monocytes-from-the-innate-immune-system-to-become-dysfunctional
 
monocytes-of-covid-19-patients">https://www.thailandmedical.news/news/international-study-finds-that-sars-cov-2-causes-epigenetic-changes-and-transcriptomic-reprogramming-in-monocytes-of-covid-19-patients
 
https://www.thailandmedical.news/news/university-of-virginia-study-finds-that-sars-cov-2-infections-triggers-reduction-in-circulating-monocytes-that-leads-to-persistent-post-covid-pulmonar
 
https://www.thailandmedical.news/news/even-mild-and-moderate-sars-cov-2-infections-causes-transcriptional-reprogramming-of-the-host-s-cd14-monocytes-resulting-in-dysfunctional-monocytes
 
https://www.thailandmedical.news/news/breaking-ongoing-u-s-study-shows-persistence-of-sars-cov-2-s1-protein-in-cd16-monocytes-in-post-acute-sequelae-of-covid-19-up-to-15-months-post-infe
 
https://www.thailandmedical.news/news/yet-another-alarming-research-finding-persistence-of-sars-cov-2-s1-protein-found-in-cd16-monocytes-of-post-covid-19-patients-up-to-15-months-after-so-
https://www.thailandmedical.news/news/harvard-led-study-confirms-that-sars-cov-2-coronavirus-infects-blood-monocytes-which-in-turn-triggers-inflammation
 
https://www.thailandmedical.news/news/breaking-covid-19-latest-sars-cov-2-induces-immunoparalysis-of-human-host,-infects-monocytes,-macrophages-and-can-cause-fibrosis-in-post-covid-19
 
https://www.thailandmedical.news/news/activation-of-type-1-dendritic-cells-cd11c-cd141-clec9a-and-exhausted-natural-killer-cells-are-key-drivers-of-post-covid-multisystem-inflammatory-synd
 
https://www.thailandmedical.news/news/study-shows-sars-cov-2-reduces-the-numbers-and-functional-competence-of-dendritic-cells-in-circulation-and-affect-responses-to-secondary-infections
 
https://www.thailandmedical.news/news/covid-19-immunology-netherlands-study-finds-that-sars-cov-2-infection-activates-dendritic-cells-via-cytosolic-receptors-rather-than-extracellular-tlrs
 
https://www.thailandmedical.news/news/covid-19-immunology:-sars-cov-2-modulates-dendritic-cell-maturation-and-suppresses-the-signaling-cascade-necessary-for-t-cell-activation
 
The Swedish study findings show that the more severe the COVID-19 infection, the slower the recovery of immune cells, such as the dendritic cells, which are necessary for the activation of the immune system.
 
Even after six months of recovery from severe COVID-19, a negative impact on several types of immune cells can still be seen.
 
Senior Author, Dr Marie Larsson, Professor of Virology at the Department of Biomedical and Clinical Sciences at Linköping University told Thailand Medical News,  "The key finding in our study is that many cell types are activated six months after the onset of the illness. This is similar to what happens to the immune cells in settings such as cancer and HIV, when there is a chronic infection in the body, and ongoing immune activation. The activation that we see could mean that the immune cells might not be optimally activated when encountering a new infection, and that they may contribute to silencing an immune response instead of enhancing it.”
 
The human immune system has two parts: the innate immune system and the adaptive immune system. The reaction of the innate system is quick but unspecific. The adaptive, specific, immune system is activated later, when there is an infection, and learns to attack viruses and bacteria that the body has encountered. The specific immune system also functions as a memory, so that the infection can be beaten much quicker the next time we encounter the same pathogen.
 
The study team took a closer look at the innate immune system, which is necessary for the body to organize any specific immune defense at all. The first time the body encounters a new virus, such as SARS-CoV-2 at the outset of the pandemic, the immune system must detect it. A group of cells called dendritic cells are necessary for this to happen. These then activate T cells, which can kill cells infected with SARS-CoV-2, and which in their turn activate B cells, which can produce antibodies that neutralize the virus. The dendritic cells are therefore a critical link between the innate and the adaptive immune systems. In an earlier study of the same patient group, the research group found negative effects on T cells.
 
The study team examined blood samples from 21 COVID-19 patients admitted to Vrinnevi Hospital in Norrköping, and from a control group consisting of 16 healthy individuals. Blood samples were taken on four different occasions, the first being when the patients were admitted and the last six to eight months later. Using spectral flow cytometry, the researchers identified different types of immune cells and their likely function.
 
Dr Larsson added, "Dendritic cell levels were extremely low at the beginning of the infection. Although they later recovered, it seems like their function has not been completely restored. The dendritic cells are more activated than they should be, and we think that this has a negative effect on the immune system.”
 
The study team also found a connection between disease severity and impact on the dendritic cells.
 
It was found that the higher the level of C-reactive protein, CRP, which increases rapidly during inflammatory processes in the body, the slower the dendritic cells recovered.
 
There are past studies that indicate that CRP may reduce the body's ability to form new dendritic cells, which could explain the slow recovery.
 
Dr Larsson said, "The conclusion we draw from this is that antiviral drugs should be administered at the earliest possible stage of the infection, to reduce the inflammation, so as to prevent the SARS-CoV-2 virus from running wild and causing a high CRP level.”
 
The study team also examined another important type of cell, monocytes, most often found in the tissue. When detecting something foreign and potentially dangerous, these cells emit signals attracting other immune cells, which sets off an inflammatory process.
 
Interestingly, it was discovered that, after six months, the distribution of various types of monocytes among the patients still differs from that among the healthy control group.
 
The study believes that the change in monocytes reflects that the body, mainly the lungs, is still healing from severe infection.
 
This can also help explain some of the symptoms seen in certain Long COVID patients.
 
For the latest COVID-19 News, keep on logging to Thailand Medical News.