Chimeric lymphocytes destroyed HIV
GM lymphocytes defeated HIV in cell culture and spleen of mice
Ekaterina Kharybina, N+1
An American group of researchers has shown the effectiveness of using multi-specific duoCAR-T lymphocytes against HIV. The obtained GM lymphocytes destroyed cells infected with different strains of HIV-1 in culture and in the spleen of mice. Some variants of CAR-T were themselves resistant to virus penetration. The results are published in Science Translational Medicine (Anthony-Gonda et al., Multispecific anti-HIV duoCAR-T cells display broad in vitro antiviral activity and potential in vivo elimination of HIV-infected cells in a humanized mouse model).
Genetic modification of T cells is one of the methods of immunotherapy for blood cancer. The Chimeric antigen receptor (CAR) gene is injected into the patient's T cells. Such chimeras consist of a variable antibody region recognizing a specific antigen and an intracellular domain activating the T cell (CAR-T). CAR-T lymphocytes recognize the antigen on the surface of the target cell, activate and destroy it.
Despite the breakthrough in oncology, attempts to treat HIV with CAR-T cells have not been successful. The HIV-1 envelope contains complexes of gp120 and gp41 glycoproteins, which bind to the receptors of the patient's immune cells, so that viruses penetrate inside. After that, the virus envelope proteins remain on the cell membrane. HIV is a retrovirus, so its enzyme – reverse transcriptase – transcribes the RNA of the virus into DNA, which is then embedded in the host genome. Reverse transcriptase is often wrong, so the virus proteins change, which is one of the main problems of HIV therapy.
Two years ago, it was shown that a hybrid protein with m36.4 and mD1.22 domains binding to gp120 sites stops HIV-1 infection. This effect was enhanced by the addition of protein C46 (an analogue of T20, or enfuvirtide, an antiretroviral drug), which interacts with gp41 and prevents the fusion of the virus envelope with the cell membrane.
Based on these data, an American group of researchers led by Boro Dropulić developed several variants of CAR-T cells whose receptors carried m36.4, mD1.22 and C46, and tested their effectiveness against HIV-1 in vitro and in vivo. Thus, monoCAR-T and duoCAR-T cells carrying one and two receptors, respectively, were obtained. Depending on the presence of m36.4, mD1.22 and C46 domains, they were mono-, di- and trispecific.
First, the researchers confirmed the ability of the obtained CAR-T cells to bind the gp120/gp41 complex in solution. After that, the scientists tested the ability of different CAR-T cells to inhibit infection in HEK 293T cell culture and assessed the degree of their activation. CAR-T lymphocytes fought infection well, and duoCAR-T was more effective than monoCAR-T.
For further experiments, the authors of the article introduced 11 different HIV-1 strains into the culture of human peripheral blood mononuclear cells (MCPC, PBMC). It turned out that CAR-T cells effectively destroyed MCPCS infected with antibody-resistant HIV-1 strains. It was also shown that in the presence of the m36.4 domain, CAR-T lymphocytes themselves are not susceptible to HIV-1 penetration.
To test the technique in vivo, scientists used immunodeficient NSG mice, which were injected into the spleen with a mixture of human MCPC infected with HIV-1 and duoCAR-T cells. A week later, viral DNA was practically absent in the spleen of mice: duoCAR-T destroyed infected cells. In such mice, infection inhibition was also shown for a month. The advantage of CAR-T cells in comparison with therapeutic antibodies, therefore, was the long-term control of HIV infection.
According to the authors of the article, such therapy can destroy latent HIV-infected cells that are not always computable by existing methods. The advantages of multi-specific duoCAR-T should also contribute to the early start of clinical trials.
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