Microorganisms in the gut boost the immune system’s ability to fight a herpes virus that can cause fatal brain inflammation

A recent study from the Beckman Research Institute in California revealed a surprising link between gut bacteria and inflammation. The findings, which were published in the journal Nature Communications, identified an envelope molecule from Bacteroides fragilis to have anti-inflammatory properties. According to the researchers, the molecule – which they called capsular polysaccharide A (PSA) – promotes protective and anti-inflammatory responses during a viral infection. In particular, it can be used to protect the body against herpes simplex encephalitis (HSE), a severe form of brain inflammation with a 70 percent mortality rate without treatment.

“This mouse study shows that B. fragilis PSA can temper the immune system so that infection does not result in an uncontrolled, potentially fatal inflammatory response in the brain,” explained Edouard Cantin, an immunology and virology expert at Beckman and co-author of the study. “Although herpes simplex encephalitis is a rare brain inflammation disorder, the lessons we learned here might, with more research, be applicable to other viral infections such as other herpes viruses, influenza virus, West Nile virus and maybe even viral respiratory diseases — conditions where inflammation begins to jeopardize the health of your body and brain function.”

A rare infection and a gut bacterium

HSE is a rare neurological condition that affects around 2,000 people in the U.S. every year. While it is uncommon, it can progress rapidly and often has fatal results.

HSE occurs when the herpes simplex virus enters the brain. The virus has two types: HSV1 or oral herpes, and HSV2 or genital herpes. HSV1 infection is known to cause cold sores. While most cases of HSE are associated with HSV1, there have been rare cases in which HSV2 was the cause of HSE. It’s worth noting that at least 90 percent of adults become infected with HSV1 in their lifetime, but the chances of it becoming HSE are rare.

A person with HSE might start out experiencing flu-like symptoms like headache and fever for up to five days. If left untreated, these can progress to personality and behavioral changes, seizures, hallucinations, altered levels of consciousness, and ultimately death.

Aside from having a high mortality rate, HSE can also leave a survivor with lifelong complications, chief of which are epilepsy, amnesia, and cognitive impairment. As HSE affects the temporal lobe which governs memory, a common complication seen in people post-infection is memory loss or impairment.

In the present study, the team investigated the anti-inflammatory property of PSA using a murine model of HSE. One group was treated with PSA prior to being infected with HSV1, while the other group was given a placebo. To simulate what happens in a clinical setting, both groups received delayed treatment with acyclovir, an anti-viral used to treat herpes infections. The team noted that only mice pretreated with PSA survived the infection. They also observed that these mice had significantly reduced brain inflammation and altered biomarkers.

According to the researchers, their findings lend evidence to the brain health-boosting benefits of consuming certain probiotics – a subject that scientists are still exploring. (Related: The health of your gut microbiome could predict your risk of heart disease, researchers find.)

“[The] consumption of certain prebiotics, probiotics or synbiotics may enhance your body’s natural ability to suppress inflammatory diseases,” said Ramakrishna Chandran, the lead author of the study. “It seems reasonable that what you decide to eat may affect your overall health and ability to fight off disease.”

Adding more probiotics to your diet

Some people may have second thoughts about using probiotics or doubt their health benefits. However, many probiotic foods have been around for a long time.

Here are just a few examples. (h/t to Healthline.com)

• Kimchi: A staple in Korean dishes, kimchi contains lactic acid bacteria that boost digestive health. It’s also a rich source of vitamins K and B2.
• Miso: A traditional Japanese seasoning made with fermented soybeans, miso is a great source of fiber and protein. For women, consuming miso has been linked to a lower risk of stroke.
• Yogurt: The most well-known on this list, yogurt is also one of the best sources of probiotics, including lactic acid bacteria and bifidobacteria. When choosing yogurt, go for those with live cultures and no added sugars.

Digestion.news has more on the gut microbiome and its role in human health.

Sources include:

ScienceDaily.com

GulfNews.com

RareDiseases.Info.NIH.gov

Encephalitis.info

Nature.com

Healthline.com