Tag Archives: Antiretroviral

Microbiology

Monocytes may be a stable reservoir of HIV in patients taking antiretroviral therapy

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Reviewed by Emily Henderson, B.Sc.Mar 27 2023

To develop treatments that may one day entirely rid the body of HIV infection, scientists have long sought to identify all of the places that the virus can hide its genetic code. Now, in a study using blood samples from men and women with HIV on long-term suppressive therapy, a team led by Johns Hopkins Medicine scientists reports new evidence that one such stable reservoir of HIV genomes can be found in circulating white blood cells called monocytes.

Monocytes are short-lived circulating immune cells that are a precursor to macrophages, immune cells able to engulf and destroy viruses, bacteria and other cells foreign to the host.

In the current research, published March 27 in Nature Microbiology, the scientists found evidence that blood samples from people with HIV undergoing long term, standard antiretroviral therapy contained monocytes that harbor stable HIV DNA capable of infecting neighboring cells.

The scientists say the findings may provide a new direction for efforts to improve therapies and eventually cure HIV, which affects more than 34 million people worldwide, according to the World Health Organization. Current antiretroviral drugs can successfully suppress HIV to nearly undetectable levels, but have not resulted in total eradication of the virus.

We don’t know how critical these monocytes and macrophages are to eradication of HIV, but our results suggest we should continue research efforts to understand their role in this disease.”

Janice Clements, Ph.D., professor of molecular and comparative pathobiology, Johns Hopkins University School of Medicine

Scientists have long known that HIV stashes its genome most often in a type of immune cell called a CD4+ T-cell. These hiding places are known as reservoirs.

“To eradicate HIV, the goal is to find biomarkers for cells that harbor the HIV genome and eliminate those cells,” says Rebecca Veenhuis, Ph.D., assistant professor of molecular and comparative pathobiology at the Johns Hopkins University School of Medicine.

To further study the role of monocytes and macrophages in circulating blood as HIV reservoirs, the Johns Hopkins-led team of scientists obtained blood samples between 2018 and 2022 from 10 men with HIV, all of them taking long-term, standard antiretroviral medications.

The researchers extracted blood cells from the samples and grew the cells in the laboratory. Typically, monocytes transform very quickly -; within about three days -; into macrophages, producing monocyte-derived macrophages.

All 10 men had detectable HIV DNA in their monocytes-turned-macrophages, but at levels 10 times lower than those found in the men’s CD4+ T cells, the well-established HIV reservoir.

For the next phase of the research, to determine if HIV genomes were present in monocytes prior to macrophage differentiation, the team used an experimental assay to detect intact HIV genomes in monocytes. The assay was based on one that fellow Johns Hopkins scientist Robert Siliciano, M.D., Ph.D., developed in 2019 to detect the HIV genome in CD4+ T cells.

The scientists, including research associate Celina Abreu, Ph.D., used the assay on blood samples taken from another group of 30 people (eight men from the first group and 22 female participants) with HIV, also treated with standard antiretroviral therapy. The researchers found HIV DNA in the CD4+ T cells and in monocytes of all 30 participants.

The scientists were also able to isolate HIV produced by infected monocytes from half of the research participants. The virus extracted from these cells was able to infect CD4+ T cells.

Three of the participants had their blood examined several times over the four-year study period, and each time, the scientists found HIV DNA and infectious virus produced by their monocyte-derived macrophages. “These results suggest that monocytes may be a stable reservoir of HIV,” says Clements.

In further research, the Johns Hopkins research team plans to pinpoint the subset of monocytes found to harbor HIV DNA and the source of these infected cells.

Source:

Johns Hopkins Medicine

Journal reference:

Veenhuis, R. T., et al. (2023). Monocyte-derived macrophages contain persistent latent HIV reservoirs. Nature Microbiology. doi.org/10.1038/s41564-023-01349-3.

Microbiology

Myeloid cells can harbor HIV in people taking antiretroviral therapy

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Reviewed by Emily Henderson, B.Sc.Mar 27 2023

A subset of white blood cells, known as myeloid cells, can harbor HIV in people who have been virally suppressed for years on antiretroviral therapy, according to findings from a small study supported by the National Institutes of Health. In the study, researchers used a new quantitative method to show that HIV in specific myeloid cells—short-lived monocytes and longer-lived monocyte-derived macrophages—can be reactivated and infect new cells. The findings, published in Nature Microbiology, suggest that myeloid cells contribute to a long-lived HIV reservoir, making these cells an important but overlooked target in efforts to eradicate HIV.

Our findings challenge the prevailing narrative that monocytes are too short-lived to be important in cure efforts. Yes, the cells are short-lived, but our follow-up data show that HIV can persist in monocytes over several years in people who are virally suppressed. The fact that we can detect HIV in these cells over such a long period suggests something is keeping the myeloid reservoir going.”

Rebecca Veenhuis, Ph.D., study author, assistant professor of molecular and comparative pathobiology and of neurology at Johns Hopkins University School of Medicine, Baltimore

The study, led by Veenhuis and colleagues at Johns Hopkins University School of Medicine, was supported by the National Institute of Mental Health, the National Institute of Allergy and Infectious Diseases, and the National Institute on Drug Abuse, all part of NIH.

Antiretroviral medications are effective in treating HIV because they prevent the virus from infecting new cells and multiplying. However, HIV may still exist in cells that are in a resting, or latent, state, creating an HIV reservoir. CD4 T cells, a type of white blood cell, are the most well-studied HIV reservoir. Identifying HIV reservoirs is critical to cure efforts, as latent HIV can be reactivated if people stop taking antiretroviral medications.

Monocytes are immune cells that circulate in the blood for about 3 days before traveling to tissue in various parts of the body, including the brain, where they can mature into macrophages. To date, it has not been clear whether latent HIV in these cells can become active again and infect other cells.

“What’s really important in the long run is understanding how monocytes contribute to the tissue macrophage reservoir,” explained Janice Clements, Ph.D., senior author on the study and professor of molecular and comparative pathobiology at Johns Hopkins University School of Medicine. “If monocytes can carry virus to the brain, or lung, or another part of the body and infect resident macrophages that are self-renewing and live almost indefinitely, that’s a real problem.”  

In the study, Veenhuis, Clements, and colleagues first measured HIV DNA in myeloid cells in a sample of 30 participants with HIV, all of whom were virally suppressed and had been on antiretroviral therapy for at least 5 years. They found detectable levels of HIV genetic material in monocytes and macrophages, though the levels were much lower than those observed in CD4 T cells. In some participants, the HIV genetic material found in monocytes was intact, which suggests it may be capable of infecting other cells if reactivated.

They then used the new quantitative method they developed to directly measure viral spread from HIV found in myeloid cells. The researchers isolated monocytes from blood samples taken from 10 participants and nurtured the monocytes in cultures that contained antiretroviral drugs, to replicate the participants’ baseline physical state. After the monocytes differentiated into macrophages, the researchers introduced an immune activating agent and then added fresh white bloods cells to allow for the virus to spread to new cells.

The researchers collected samples from the cell cultures several times over the next 12 days. They included checkpoints throughout the process to ensure that infected CD4 T cells did not interfere with their measurements.

The results showed that cultures from five of the 10 participants had detectable HIV genetic material in monocyte-derived macrophages that could be reactivated to infect other cells and produce more virus. The participants who had these reactivatable reservoirs of HIV in monocyte-derived macrophages had higher overall levels of HIV DNA material.  

Follow-up data from three participants showed that this reservoir can be long-lived, harboring latent HIV for months to several years. These reservoirs were stable and could be reactivated over time, indicating that monocyte-derived macrophages could contribute to viral rebound if antiretroviral treatment is disrupted.

The researchers note that this study is small and larger studies with more diverse participant pools will be essential to accurately estimate the proportion of people who have latent HIV in myeloid cells. Investigating the mechanisms that replenish the monocyte reservoir over time is a critical next step in this research.

“These findings underscore the importance of broadening the scope of HIV cure efforts,” said Joshua A. Gordon, M.D., Ph.D., director of the National Institute of Mental Health. “Shifting away from a sole focus on CD4 T cells to thinking about CD 4 T cells and myeloid cells together, in context, will propel the field toward more promising strategies for eradicating HIV.”

Source:

National Institutes of Health

Journal reference:

Veenhuis, R. T., et al. (2023). Monocyte-derived macrophages contain persistent latent HIV reservoirs. Nature Microbiology. doi.org/10.1038/s41564-023-01349-3.

Microbiology

Duke receives federal funding for HIV vaccine research

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Reviewed by Emily Henderson, B.Sc.Oct 11 2022

The Duke Human Vaccine Institute (DHVI) and the Department of Surgery at Duke University School of Medicine received a grant from the National Institute of Allergy and Infectious Diseases for HIV vaccine research that could total $25.9 million with full funding over five years.

The funding supports a multi-institutional effort called The Consortium for Innovative HIV/AIDS Vaccine and Cure Research that is built around two areas of scientific focus: identification of the components and the mechanisms of protection of preventive vaccines; and the use of the newly identified preventive vaccines along with other immune therapies in advancing potential treatments and/or cures.

The grant’s principal investigators are Guido Ferrari, M.D., a professor in the Department of Surgery and research professor in the Department of Genetics and Microbiology, and Wilton Williams, Ph.D., an associate professor in the departments of Surgery and Medicine, and assistant professor in the Department of Immunology at Duke University School of Medicine.

The researchers will lead work that builds upon ongoing HIV vaccine development research at DHVI and expands investigations of vaccine strategies, including innovative mRNA approaches that induce protective immune responses in non-human primate models.

This grant is synergistic with everything going on at Duke, notably the Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery (CHAVI-ID) initiative to design an HIV vaccine. We are excited about the wonderful science that will be done in the context of this grant. It expands the capacity at Duke, UNC and others who are collaborating on this effort to move forward with both vaccines and potential cures.”

Barton Haynes, Director of the DHVI

Combining vaccine approaches with cure efforts is designed to stimulate innovative collaborations toward both. Studies in nonhuman primates will investigate how effective HIV/AIDS vaccines protect from initial infection and systemic infection.

Vaccines and other immune interventions will also be used as cure strategies with the goal of eliminating all the infection in the cells. While advances have been made in boosting cellular and antibody immunity, it remains unclear whether the boosted immune response can prevent reinfection after antiretroviral treatments are stopped. With the newly funded grant, the researchers hope to answer that and other questions.

“This grant enables us to do something current vaccine research is not funded to do – explore vaccines with a mission to cure,” Williams said. “Right now, it’s either prevention or cure, and we want to achieve a combination of those things.”

Ferrari said vaccine research has advanced far enough that researchers can now begin applying potential components of vaccines, as well as new technologies such as mRNA vaccine design, to explore ways of eradicating the HIV from infected cells.

“The beauty of mRNA is its ability to be adapted quickly and we can produce it in a timely manner to address new variants, which is important for HIV,” Ferrari said. “We will now focus on how we can capitalize on the current science to eradicate infection.”

“The science underpinning this program has broad applicability, spanning from the immediate goals of eliminating HIV disease, to a more generalizable harnessing of the immune system to prevent emerging infectious diseases, control cancer, and accelerate our understanding of autoimmunity and transplant biology,” said Allan D. Kirk, M.D., Ph.D., chair of the Department of Surgery.

“Our department sees the promise of basic investments like these for transformational approaches to care that do not traditionally fall within a surgical department,” Kirk said. “Drs. Williams and Ferrari are vital members of our translational science community.”

In addition to Williams and Ferrari, collaborators at Duke are Priyamvada Acharya, Mihai Azoitei, Derek Cain, Thomas Denny, Robert J. Edwards, Barton Haynes, David Montefiori, Justin Pollara, Keith Reeves, Wes Rountree, Kevin Saunders, Shaunna Shen, Rachel Spreng, Georgia Tomaras, Kevin Wiehe, Kelly Cuttle and Cynthia Nagle.

Study partners include Katharine Barr, Michael Betts, Beatrice Hahn, George Shaw, Drew Weissman at the University of Pennsylvania; Richard Dunham and David Margolis at the University of North Carolina at Chapel Hill; Sampa Santra at Harvard University; Andrew McMichael, Persephone Borrow and Geraldine Gillespie at Oxford University; Bette Korber and Kshitij Wagh at Los Alamos National Laboratory; and Mark Lewis at BIOQUAL.

Source:

Duke University School of Medicine