HIV can hide in the brain, waiting to infect other organs later

BEIJING, June 29 (Xinhua) — A new study of mouse and human body tissue has found that HIV can seek refuge in the brain when receiving antiretroviral treatment, waiting for treatment to stop before re-infecting other organs in the body, according tomedia reports. If left untreated, HIV (the HIV virus that causes AIDS) destroys the immune system, leaving the body with no recourse in the face of deadly diseases.

HIV can hide in the brain, waiting to infect other organs later

The combination of multiple drugs can significantly reduce the level of the virus in the body, so that it is too low to detect, the symptoms of the disease will mostly disappear, and the treatment of the person is no longer contagious to others. But cocktail therapy drugs must be taken daily, and once stopped, the virus could return from “sanctuary” hidden around the body.

The new study, published June 11 in the journal Public Library of Science: Pathogens, suggests that one of the safest places for HIV is astrocytes in the brain. The study notes that these cells make up about 60 percent of all cells in the human brain. The study authors estimate that about 1% to 3% of astrocytes in the brains of HIV-infected people may be lurking in THE virus.

“As a hideout for the virus, even at 1%, it’s a pretty high percentage. Lena Al-Harthi, a professor and director of the Department of Microbial Pathogens and Immunology at Rush University Medical Center in Chicago, said, “If you want to find a cure for HIV infection, you can’t ignore the role of the brain as a virus ‘hiding place’. “

Alhadi and colleagues came to their conclusions using a model of HIV in a mouse injected with human cells, as well as autopsy results on the human brain. While both experiments have helped researchers better understand the role of astrocytes in HIV infection, one expert said more needs to be done to determine how the virus has captured “bases” in the human body.

“Animals are not humans, but animal models can tell us a lot. “Dr. N. Nadlov, professor of immunology at Weill Cornell Medical School, said: “It’s a good idea to do this. Lishomwa Ndhlovu noted that he was not involved in the study. If astrocytes can be used as a hideout for HIV viruses in the human body, and viruses can leave the brain and infect other organs as shown in mouse models, “we will try to kill the virus in these ‘shelters’ before we can successfully cure HIV infection.” “

Quietly in the air

Astro-shaped glial cells, such as stars, contain many types and play a key role in the central nervous system. These cells can deliver nutrients to neurons and stimulate or reduce the inflammatory response in the brain. Astrogliosis cells are also responsible for shaping and maintaining the connectivity structure of the central nervous system, as well as strengthening the blood-brain barrier (a layer of tissue that separates circulating blood from brain cells).

Scientists know that HIV can penetrate the brain, with some infected people developing symptoms of dementia and other cognitive impairments.

“The role of astrocytes in HIV infection has been controversial. Alhadi pointed out. Previous studies have shown that astrocytes can be infected with HIV, but most studies use viruses in petri dishes that may not accurately replicate the process of infection in animal live animals. Several studies have used “traditional” methods, such as proteins or genetic material that label viruses with fluorescent substances, but may not be sensitive enough to low levels of HIV in astrocytes. None of these studies show edified whether, once infected, astrocytes can be released in some way and infect edited in organs other than the brain.

To address this critical issue, Alhadi and her team developed two new mouse models.

First, the researchers put astrocytes from embryonic brain cells into a petri dish, infected with HIV, and then injected the infected cells into the brains of laboratory mice, a group of newborn mice and a group of adult mice. It was found that in both groups of mice, the virus-infected astrocytes were transmitted to CD4 cells. CD4 cells are a class of immune cells responsible for coordinating the body’s immune response and are one of the main targets of HIV.

After contracting the virus from astrocytes, CD4 cells leave the brain and enter other tissues. In other words, when “the brain is already infected with HIV, the virus can leave the brain and re-infect peripheral organs.” “

The authors note that the spleen and lymph nodes are particularly susceptible to infection during this process. If it can block the transfer of CD4 cells, or can cut off the virus transmission chain.

To ensure that the virus can infect astrocytes on its own without any human assistance, the researchers also conducted another experiment, injecting healthy human astrocytes into mice and then infecting them with HIV. In this case, some human astrocytes are still infected with the virus and release the virus to other parts of the body. It’s worth noting that even if the mice received cocktail therapy, the virus could escape from the brain, except that it had “lower levels” compared to untreated mice. If treatment is stopped, the virus that escapes from the brain can cause a full-blown infection.

For further confirmation, the authors also analyzed the donated brains of four HIV-infected people. All four received effective cocktail therapy before their lives. (The study does not specify the cause of death for each donor, but notes that at the time of their death, the viral water in the body was effectively inhibited by cocktail therapy on average.) The team found that a small number of stargliating cells had genetic material in the nucleus of the HIV virus, indicating that those cells had been infected.

Healing

Many of the problems associated with astrocytes and HIV remain unresolved. As Alhadi points out, some types of astrocytes can hide HIV, while others can’t. In addition, although mouse experiments have shown that HIV can leave the brain, autopsy analysis of human donors does not confirm that this can also occur in humans.

“Animal models don’t work perfectly,” says Alhadi, so there may be differences in the way viruses are infected in animals and humans.

As Nadlov points out, in the natural process of HIV infection, each time the virus replicates, genetic variation accumulates, and the genetic material needed for infection may be lost in the process. To fully understand the role of astrocytes in HIV infection, researchers also need to understand how high levels of the virus in these cells can actually cause infection.

Alhadi and his team have begun to address this problem by analyzing the brain tissue of infected people and fragments of HIV genetic material found therein, but further research is needed to confirm that the virus found in it can infect cells and transfer to other organs in the body. In addition, Nadlov said, scientists also need to understand the exact path of HIV leaving the brain and infecting other organs. This information is crucial in developing brain-specific therapies and successfully curing HIV infections.