Some surprising discoveries about the body's initial responses to HIV infection have been made by researchers at UC Davis. Studying simian immunodeficiency virus (SIV), the team found that specialized cells in the intestine called Paneth cells are early responders to viral invasion and are the source of gut inflammation by producing a cytokine called interleukin-1 beta (IL-1β).
Though aimed at the presence of virus, IL-1β causes breakdown of the gut epithelium that provides a barrier to protect the body against pathogens. Importantly, this occurs prior to the wide spread viral infection and immune cell killing. But in an interesting twist, a beneficial bacterium, Lactobacillus plantarum, helps mitigate the virus-induced inflammatory response and protects gut epithelial barrier. The study was published in the journal PLoS Pathogens.
One of the biggest obstacles to complete viral eradication and immune recovery is the stable HIV reservoir in the gut. There is very little information about the early viral invasion and the establishment of the gut reservoir.
"We want to understand what enables the virus to invade the gut, cause inflammation and kill the immune cells," said Satya Dandekar, lead author of the study and chair of the Department of Medical Microbiology and Immunology at UC Davis.
"Our study has identified Paneth cells as initial virus sensors in the gut that may induce early gut inflammation, cause tissue damage and help spread the viral infection. Our findings provide potential targets and new biomarkers for intervening or blocking early spread of viral infection," she said.
In the study, the researchers detected a very small number of SIV infected cells in the gut within initial 2.5 days of viral infection; however, the inflammatory response to the virus was playing havoc with the gut lining. IL-1β was reducing the production of tight-junction proteins, which are crucial to making the intestinal barrier impermeable to pathogens. As a result, the normally cohesive barrier was breaking down.
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"The epithelium is more than a physical barrier," said first author Lauren Hirao. "It's providing support to immune cells in their defense against viruses and bacteria."
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"Understanding the players in the immune response will be important to develop new therapies," said Hirao. "Seeing how these events play out can help us find the most opportune moments to intervene."
Source-Eurekalert