Stem cells might finally give us the tools to fight off the human immunodeficiency virus (HIV), the pathogen responsible for AIDS, according to a new paper. Although the findings are still quite early, and based on an animal model, the authors are confident that the findings will translate well to human biology.
Researchers at the University of California Davis report that a specialized type of stem cell -- mesenchymal stem cells (MSCs) -- can boost the body's immune response against SIV, the simian immunodeficiency virus, in primates. SIV is the equivalent of HIV but only infects non-human primates.
The discovery, they explain, makes it possible for us to establish a realistic roadmap for a multi-pronged HIV eradication strategy.
STEMing the infection
"Impaired immune functions in HIV infection and incomplete immune recovery pose obstacles for eradicating HIV," said Satya Dandekar, senior author of the paper and the chairperson of the Department of Medical Microbiology and Immunology at UC Davis. "Our objective was to develop strategies to boost immunity against the virus and empower the host immune system to eradicate the virus".
"We sought to repair, regenerate, and restore the lymphoid follicles that are damaged by the viral infection."
Lymphoid tissue in the gut is a key site for HIV replication during the early stages of an infection, the team explains, and later forms viral reservoirs that make removing the pathogen very difficult. Previous research has shown that once it gets a foothold here, HIV causes a severe decrease in immune cells in the gut's mucosal tissues (its lining) and attacks its epithelial barrier lining, causing a leaky gut.
This lymphoid tissue houses structures known as follicles, whose job is to mount long-term counterattacks against pathogens in our bodies by producing antibodies against them. This, unfortunately, means that an HIV infection impairs the same structures that are meant to defeat it.
Antiretroviral drugs are effective in suppressing HIV's ability to replicate, but they don't repair the damage the virus already caused to these follicles. So they can keep the infection suppressed, but on their own, they can't form an efficient treatment against the disease.
However, the team reports that bone marrow-derived MSCs can. They carried out their experiment using a rhesus macaque model that had impaired immunity and disrupted gut functions due to an SIV infection. These cells were able to modulate, alter, and remodel the damaged mucosal site -- in essence, they could repair the virus-caused damage.
"We are starting to recognize the great potential of these stem cells in the context of infectious diseases. We have yet to discover how these stem cells can impact chronic viral infections such as AIDS," Dandekar said.
Following the procedure, the authors saw a rapid rise in antibodies and immune T cell levels, both of which engaged with the infection.
Ideally, such approaches would be used in conjunction with current HIV treatments. They can repair our bodies' natural defenses, while antiretroviral compounds keep the infection in check. That being said, the MSCs were able to improve the hosts' response against the infection even by themselves.
The paper "Gut germinal center regeneration and enhanced antiviral immunity by mesenchymal stem/stromal cells in SIV infection" has been published in the journal JCI Insight.