How Rotavirus Causes Severe Gastrointestinal Diseases

Rotavirus is a major cause of diarrhea and vomiting, especially in children, killing about 128,000 people annually. The virus causes disease by infecting the enterocytes of the small intestine, but only a small part of the susceptible cells are infected with the virus. In the mid-’90s, scientists suggested that a small portion of infected cells promote serious disease by sending signals that disrupt the normal functioning of adjacent uninfected cells. The nature of the signal remains a mystery.

In the current study published in the journal Science, A team led by researchers at Baylor College of Medicine, Rotavirus-Infected cells It releases a signaling molecule identified as adenosine diphosphate (ADP). It binds to the cell receptor P2Y1 on adjacent cells. When P2Y1 is activated by ADP, a signal called intercellular is generated. calcium Waves of these uninfected cells.Disruption of ADP binding to that receptor can reduce the severity of diarrhea in a mouse model of the disease and target P2Y1. Effective strategy Control viral diarrhea Human population..

“Previous studies using fluorescent calcium sensors and time-lapse imaging have found that cells infected with rotavirus show abnormal calcium signals and can be visualized as bright pulses of intercellular calcium waves emitted by infected cells. “I did,” said the corresponding author, Dr. Joseph Heiser, an assistant professor of virology and microbiology, and a member of the Alquec Center for Metagenomics and Microbiology Studies in Baylor. “Calcium signaling is known to be associated with various aspects of rotavirus infection, and our study revealed the dynamic nature of rotavirus-induced changes.”

In the current study, researchers conducted experiments with low-dose viruses that showed dynamic calcium signaling not only in virus-infected cells, but also in adjacent non-infected cells surrounding infected cells. I noticed that they generated pulses of the virus, which were coordinated with those of the infected cells. This observation suggested that infected cells may be causing intercellular calcium waves in uninfected cells.

Researchers observe the concept proposed in the mid-’90s, suggesting that rotavirus-infected cells signal adjacent uninfected cells to disrupt function and promote diarrhea and vomiting. Connected.

“Live fluorescence microscopy videos showing intercellular calcium wave signaling in both rotavirus-infected and non-infected cells provide an unprecedented means of investigating the properties of unspecified proposed signals. “I did,” said lead author Dr. Alexandra L. Chan. Graham, MD / Ph.D. A student of a doctoral training program with a PhD. A treatise working at Heiser Lab.

Find the signal

Chang-Graham, Hyser, and their colleagues used three different laboratory models to identify signals that trigger intercellular calcium waves in uninfected cells. They used a monkey kidney cell line commonly used to study rotavirus. They also collaborated with a culture system that reproduces many of the characteristics of human enteritis, human infections, and neonatal mouse models of rotavirus infection and diarrhea. Their study showed that suspicious triggers of calcium waves, such as prostaglandin E2 and nitric oxide, did not trigger a calcium reaction. They then tested ATP and ADP, known mediators of calcium signaling that were not previously associated with rotavirus infection. They found that rotavirus-infected cells induce intercellular calcium waves by releasing ADP that binds to the receptor P2Y1 on uninfected adjacent cells. Knocking out the P2Y1 gene, which interferes with ADP signaling, reduced intercellular calcium waves.

“Throughout the three model systems, we have consistently found evidence that rotavirus-infected cells signal uninfected cells with ADP, which contributes to the severity of the disease,” said Chang-Graham. I have. “We think it’s a paradigm shift that the actual signal, ADP, wasn’t even on radar before.”

ADP signaling is involved in the induction of severe rotavirus symptoms

Further research reveals a previously unknown role of ADP in rotavirus infection and replication, spotting ADP as an important trigger for multiple factors involved in rotavirus-induced severe diarrhea and vomiting. The light was shined. For example, researchers have found evidence that ADP signaling increases rotavirus infection, expression of the inflammatory cytokine IL1-alpha, and secretion of serotonin, a diarrhea-inducing factor. ADP signaling also increases the expression of enzymes that produce prostaglandins and nitric oxide, which can lead to the increase in these compounds observed in rotavirus infections. Preventing ADP signaling and intercellular calcium waves reduced the production of the above compounds.

“Finally, we found that inhibition of the P2Y1 receptor reduced the severity of rotavirus-induced diarrhea in a mouse model,” said Chang-Graham. “Using intercellular calcium waves, rotavirus amplifies its ability to cause disease cell It is directly infected. This is the first virus to be found to activate ADP-mediated intercellular calcium waves. This may be a strategy that other viruses also use to cause disease in the host. “

“Our findings add a new and highly powerful signaling pathway to the mechanisms that cause rotavirus diarrhea,” Heiser said. “This is exciting when it comes to treatment, as some drugs targeting P2Y1 are currently undergoing preclinical studies as anticoagulants. Such drugs have proven safe for children. If so, it may be reused for the treatment of diarrhea caused by rotavirus infection. ”