E’ stato pubblicato oggi sulla prestigiosa rivista scientifica Nature Medicine un importante lavoro di Mirko Paiardini (e altri) sul ruolo di farmaci biologici nel trattamento delle infezioni da HIV-1.
Mirko Paiardini, attualmente alla Emory University (USA) oltre ad essersi laureato a Urbino e avervi svolto il dottorato di ricerca, è anche attualmente visiting professor alla Carlo Bo. Nel paper sono inclusi anche Barbara Cervasi (altra biologa laureata in Urbino) e Luca Micci (un altro laureato in biotecnologie) oltre al professor Guido Silvestri, nato a Senigallia e anch’egli docente alla Emory, che nel novembre scorso ha inaugurato il 514° anno accademico di Uniurb ed è promotore assieme a Roberto Burioni del “Patto trasversale per la scienza”
I dettagli della rilevante scoperta vengono descritti nel seguente comunicato originale della
Emory University:
IMMUNOTHERAPY COMBO ACHIEVES RESERVOIR SHRINKAGE IN HIV MODEL
Stimulating immune cells with two cancer immunotherapies together can shrink the size of the viral “reservoir” in SIV
(simian immunodeficiency virus)-infected nonhuman primates treated with antiviral drugs, Emory University researchers
and their colleagues have concluded. The reservoir includes immune cells that harbor virus despite potent antiviral drug
treatment.
The findings, reported in Nature Medicine, have important implications for the quest to cure HIV because reservoir
shrinkage has not been achieved consistently before. However, the combination treatment does not prevent or delay viral
rebound once antiviral drugs are stopped. Finding an HIV cure is of critical importance as, although antiretroviral therapy
can reduce the amount of circulating virus to undetectable levels, problematic issues remain, such as social stigma in
addition to the long-term toxicity and cost of antiretroviral drugs.
“It’s a glass-half-full situation,” says senior author Mirko Paiardini, PhD. “We concluded that even a very effective
combination of antibodies that led to immune checkpoint blockade, which prevents termination of immune responses, is
unlikely to achieve viral remission as a standalone treatment during antiretroviral therapy.”
He adds the approach may have greater potential if combined with other immune-stimulating agents. Or it could be
deployed at a different point — when the immune system is engaged in fighting the virus, creating a target-rich
environment. Other HIV/AIDS researchers have started to test those tactics, he says.
Paiardini is an associate professor of pathology and laboratory medicine at Emory University School of Medicine and a
researcher at Yerkes National Primate Research Center. The study performed in nonhuman primates, considered the best
animal model for HIV studies, was carried out in collaboration with first author Justin Harper, who is Paiardini’s lab
manager at Emory; co-authors Shari Gordon and David Favre at the University of North Carolina at Chapel Hill and
GlaxoSmithKline; Katharine Bar at the University of Pennsylvania; and Jake Estes at Oregon Health & Science
University.
Although antiviral drugs are available that can suppress HIV to the point of being undetectable in blood, the virus
embeds itself in the DNA of immune cells, frustrating efforts to root it out. Only two individuals have ever achieved
what their doctors consider a durable cure, and they went through a bone-marrow transplant for leukemia or lymphoma —
not widely applicable.
Paiardini and his colleagues reasoned chronic viral infection and cancer produce similar states of “exhaustion”: immune
cells (T cells) that could fight virus or cancer are present, but unable to respond. In long-term HIV or SIV infection, T
cells harboring the virus display molecules on the cell surface that make them targets for checkpoint inhibitors, cancer
immunotherapy drugs that are designed to counteract the exhausted state. In the context of HIV infection, these types of
drugs have been tested to a limited extent in people living with HIV who were being treated for cancer.
In the Nature Medicine paper, the researchers used antibodies to block the surface molecules CTLA-4 and PD-1. In
monkeys that received both CTLA-4- and PD-1-blocking agents, researchers observed a stronger activation of T cells,
compared to only PD-1 blockade. DNA sequencing of viruses in the blood revealed a broader range of viruses were
reactivated with the combination, compared to single checkpoint inhibitors.
“We observed that combining CTLA-4- and PD-1 blockade was effective in reactivating the virus from latency and
making it visible to the immune system,” Paiardini says.
In previous studies, limited shrinkage of the viral reservoir has been seen only inconsistently with single checkpoint
inhibitors or other immune-stimulating agents. Only combination-treated animals showed a consistently measurable and
significant reduction in the size of the viral reservoir. The researchers measured this with “DNAscope,” an imaging
technique to visualize infected cells within tissues. Additionally, researchers quantified the frequency of CD4 cells, the
main reservoir of HIV and SIV, harboring intact viral DNA capable of replicating.
Despite this effect, once antiviral drugs were stopped, the virus still came back to the same level in combination-treated
animals.
“We believe this is due to having much less viral antigens around after long-term antiretroviral therapy, compared with
the situation in cancer,” says Harper. “This makes it much more difficult for the immune system to recognize and kill
those cells.”
A note of caution: the equivalent combination of CTLA-4 and PD-1 blockade in humans has been tested in the context of
cancer treatment. While the two drug types can be more effective together, patients sometimes experience adverse side
effects: severe inflammation, kidney damage, or liver damage.
In the Nature Medicine paper, the combination-treated animals did not experience comparable adverse events, the
researchers reported. Further investigation is necessary to determine whether the combination of checkpoint inhibitors
exhibits an acceptable toxicity profile in people living with HIV without cancer.
Paiardini credits the Yerkes National Primate Research Center Animal Resources team for its dedicated care of the
animals involved in the study. HIV studies are complex and long-term, so animal care is the backbone of being able to
conduct such research focused on improving human health.
Emory’s Center for AIDS Research (P30AI050409), the Consortium for Innovative AIDS Research in Nonhuman
Primates (UM1AI124436), the National Institute of Allergy and Infectious Diseases (R01AI116379, R21/R33AI116171 –
– $XXX (or wherever it is appropriate to put the funding amount), the Collaboratory of AIDS Researchers for Eradication
(UM1AI126619), GlaxoSmithKline, Qura Therapeutics, the NIH director’s Office of Research Infrastructure Programs
(P51OD011132, P51OD011092), and the National Cancer Institute (HHSN261200800001E) supported this research. The
funding amount provided is for the complete NIH grant, which is covering multiple research projects and extends beyond
the research reported in this study.
Related Posts
No Comment