The skin is the outermost layer of any animals' body, including humans, that protects them against the external environment and provides the sensation of touch. Epithelial cells on the skin can recognize nucleic acid that is formed during virus replication that subsequently induces a potent inflammatory response.
This is the result of how epithelial cells protect the skin from viruses, as shown by researchers from LMU's immunologist Veit Hornung. It is an important defense mechanism for the integrity and survival of organisms.
These proteins are known as inflammasome sensors that form inflammasome complexes once activated that triggers inflammatory responses that may lead to the infected cell's death.
The researchers found that these proteins in epithelial cells bind together to the specific structure formed when the RNA of viruses replicates, underlining the importance of the skin cells as a barrier against pathogens, Phys.org reported.
Epithelial Cells vs Viruses
The researchers identified the NLRP1 protein as an inflammasome sensor, but they are uncertain how it functions as a direct sensor for alien molecules, Hornung said.
NLRP1 is commonly found in keratinocytes, cells in humans, which forms the outer layer of the skin to serve as a physical barrier protecting it from bacteria and viruses.
The researchers were able to identify how these cells react to viruses that are dissimilar with their mode of replication, called the Semilki Forest Virus (SFV), which strongly activated the NLRP1.
The study lead author Stefan Bauernfried said that "other cells are known to have barrier functions, such as cells of the bronchial epithelia, also responded to this virus by activating NLRP1, so this seems to be a general phenomenon."
The SFV was first identified in Uganda which proved to be useful in virology studies. The virus is commonly found in rodents, but can also be transmitted to humans through mosquito bites. SFV consists of single-strand RNA, and yielding a double-strand RNA occurs not side the cell which makes it perfect to activate the NLRP1 which binds perfectly to the double-stranded RNA.
Bauernfried explains that they were able to demonstrate that the NLRP1 successfully binds and is activated by the double-stranded RNA of the virus. causing inflammatory reactions as a response to the virus.
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Key Factor in Recognizing Infections
The study concluded that epithelial cells, like those on the skin, serves as a barrier against viruses and pathogens and that NLRLP1 plays a significant role in it.
Particularly speaking, the inflammasome sensor is critical in detecting viruses that could cause harm to the host. Still, the role of NLRP1 on the detection of pathogenic viruses is unclear.
Hornung explains that it is possible that well-adapted viruses could have acquired the ability to inhibit response mechanisms. But they noted that it is another topic to explore for their next research.
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