Now, new research by University of Alberta immunologist Shokrollah Elahi reveals a possible answer to the mystery of why infected people can’t get rid of HIV altogether.

Elahi and his team found that in HIV patients, killer T cells — a type of white blood cells responsible for identifying and destroying cells infected with viruses — have very little to none of a protein called CD73.

Because CD73 is responsible for migration and cell movement into the tissue, the lack of the protein compromises the ability of killer T cells to find and eliminate HIV-infected cells, explained Elahi.

“This mechanism explains one potential reason for why HIV stays in human tissues forever,” he said, adding that the research also shows the complexity of HIV infection.

“This provides us the opportunity to come up with potential new treatments that would help killer T cells migrate better to gain access to the infected cells in different tissues.”

After identifying the role of CD73 — a three-year project — Elahi turned his focus to understanding potential causes for the drastic reduction. He found it is partly due to the chronic inflammation that is common among people living with HIV.

“Following extensive studies, we discovered that chronic inflammation results in increased levels of a type of RNA found in cells and in blood, called microRNAs,” he explained. “These are very small types of RNA that can bind to messenger RNAs to block them from making CD73 protein. We found this was causing the CD73 gene to be suppressed.”

The team’s discovery also helps explain why people with HIV have a lower risk of developing multiple sclerosis, Elahi noted.

“Our findings suggest that reduced or eliminated CD73 can be beneficial in HIV-infected individuals to protect them against MS. Therefore, targeting CD73 could be a novel potential therapeutic marker for MS patients.”

Elahi said the next steps in his research include identifying ways the CD73 gene can be manipulated to turn on in patients living with HIV and off in those with MS.

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Materials provided by University of Alberta. Original written by Tarwinder Rai. Note: Content may be edited for style and length.

“With the help of advanced laboratory techniques, we were able to identify a panel of nanobodies that very effectively neutralized several variants of SARS-CoV-2,” says Gerald McInerney, professor at the Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, and joint senior author of both studies.

Despite the roll-out of vaccines and antivirals, the need for effective therapeutics against severe COVID-19 infection remains high. Nanobodies — which are fragments of antibodies that occur naturally in camelids and can be adapted for humans — are promising therapeutic candidates as they offer several advantages over conventional antibodies. For example, they have favourable biochemical properties and are easy to produce cost-effectively at scale.

In the now published studies, the labs of Gerald McInerney and Ben Murrell, also at MTC, identify several potent nanobodies derived from an alpaca immunised with SARS-CoV-2 antigens.

The first report in Nature Communications describes a single nanobody, Fu2 (named after the alpaca Funny), that significantly reduced the viral load of SARS-CoV-2 in cell cultures and mice. Using electron cryo-microscopy, the researchers found that Fu2 naturally binds to two separate sites on the viral spike, thus inhibiting the virus’ ability to enter the host cell. This part of the study was conducted in collaboration with Hrishikesh Das and Martin Hällberg at the Department of Cell and Molecular Biology at Karolinska Institutet.

The researchers next delved deeper into the alpaca’s nanobody repertoire by combining a range of advanced laboratory techniques and computational methods, resulting in a library of nanobodies described in detail.

The results, presented in Science Advances, revealed additional nanobodies that in cell cultures and mice effectively cross-neutralized both the founder and beta variant of SARS-CoV-2 and even neutralized the more distantly related SARS-CoV-1.

“These nanobodies represent promising therapeutic candidates against several SARS-CoV-2 variants,” says first author Leo Hanke, a postdoctoral researcher who established the nanobody technology in the McInerney group.

The researchers are currently applying the same techniques to identify which nanobodies from this set are best able to neutralize Omicron, the now dominating SARS-CoV-2 variant.

“Once established, these libraries can be expanded and mined for nanobodies that neutralize new emerging variants,” says Assistant Professor Ben Murrell, also joint senior author of both studies.

Funding was provided by David and Astrid Hagelén Foundation, the Clas Groschinskys Minnesfond and a Jonas Söderquist’s scholarship, European Union’s Horizon 2020 research and innovation program, Swedish Research Council, and Knut and Alice Wallenberg Foundation.

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Scientists working on the neuroscience of attention have recently become concerned that because both attention and eye movements, like microsaccades, involve the same groups of neurons in the brain, that microsaccades might be required for shifting attention.

“If microsaccades were driving attention, that would bring into question a lot of previous research in the field.” said Richard Krauzlis, Ph.D., chief of the NEI Section on Eye Movements and Visual Selection, and senior author of a study report on the research. “This work shows that while microsaccades and attention do share some mechanisms, covert attention is not driven by eye movements.”

Krauzlis’ previous research has shown that covert attention causes a modulation of certain neuronal signals in an evolutionarily ancient area of the brain called the superior colliculus, which is involved in the detection of events. When attention is being paid to a particular area — for example, the right-hand side of one’s peripheral vision — signals in the superior colliculus relating to events that occur in that area will receive an extra boost, while signals relating to events occurring somewhere else, like on the left-hand side, will be depressed.

When something shows up in our peripheral vision, we quickly shift our eyes — make a large saccade toward the event to take a better look. This movement brings the event into our high-resolution central vision. These eye movements are accompanied by a general decrease in visual signals, as the brain ignores the quickly shifting visual information received by the eye. In laboratory studies of covert attention, primates or people are directed to avoid those types of large saccades, keeping the attended event in the peripheral vision. However, involuntary microsaccades, which are accompanied by similar decreases in visual signals, often occur anyway.

In this study, led by first author Gongchen Yu, Ph.D., the researchers asked whether attention-based signal changes in the superior colliculus are driven by microsaccades, or if the two processes can be separated.

The researchers trained monkeys to hold their eyes straight ahead, while attending to their peripheral vision. The researchers would cue either the left or right side by flashing a ring on the “cued” side. After the cue, the monkeys would release a joystick if they detected a color change on the cued side, while ignoring any color changes on the uncued side. The researchers could measure changes in neuronal activity on both sides of the superior colliculus, detecting a boost to the cued side, and lower signals on the uncued side.

At the same time, the researchers used high-resolution eye-tracking cameras to measure microsaccades during the trials. Sometimes, there would be no microsaccades. In other trials, the monkeys would make a microsaccade toward the cued side, or away from the cued side. By lining up the signals based on the time any microsaccade began, the researchers found that the neuronal signals for attention in the superior colliculus were present before the microsaccade, and then would re-establish after the microsaccade.

In essence, although the eye movement would also trigger changes to neuronal signals in the superior colliculus, attention-related signals occurred independently of the eye movement signals.

“While the neuronal circuits activated by these two systems do overlap, the link between microsaccades and attention is not a causal one,” Krauzlis said.

“The majority of vision neuroscientists have been using this type of experimental system to study visual attention for decades. It’s a big relief to reconfirm that microsaccades are not the driver of the neuronal changes seen with visual attention,” said Yu. “This result means we don’t need to reevaluate decades of work!”

This study was funded by the NEI Intramural Program.

“Based on this idea, we proposed a concept that this will be a pH-responsive material. If we change the pH value, we can control the molecular diffusion,” said Dr. Qingsheng Wang, associate professor in the Artie McFerrin Department of Chemical Engineering and holder of the George Armistead ’23 Faculty Fellowship at Texas A&M.

The team’s research was published in the American Chemical Society’s journal, ACS Applied Materials & Interfaces.

Emulsion is a mixture of two or more incompatible and unmixable liquids, much like oil and water, that can be stabilized by the interference of solid particles. These solid particles tightly assemble at the fluid-fluid interface, like swim lanes in a lap pool, to prevent coalescence. This process is known as Pickering emulsion.

The success of this system is ultimately made possible by the use of graphene quantum dots (GQDs) containing zwitterionic properties. Using several sheets of GQDs stacked together, the research team is able to not only stabilize emulsion, but also control the molecular diffusion on the interface by adjusting its pH values, much like flipping a light switch. These sheets together measure less than 5 nanometers in thickness. To put this into perspective, the average human hair is anywhere from 80,000 to 100,000 nanometers wide.

The functionalized GQDs are composed of nanocarbon materials containing zwitterionic structure, which is formed from nanoparticles that contain an equal amount of both positive and negative charges while still remaining electronically neutral. After the nanoparticles are added to the interface, they separate the two fluids by making one side hydrophobic and the other side hydrophilic.

This electronic makeup also makes it possible to control the overall pH of the interface. By adjusting the pH values, these GQDs can be finely tuned to both block and unblock an oil-water interface. Changing the nanoplatelets on the interface to the same charge means that they will be disassembled, thus creating a more stable emulsion system.

“This is going to help us design a good system in high-performance fire suppression. In addition, because we can control the release, this could be promising for drug delivery and enhanced oil recovery,” Wang said. “Usually, this is very difficult to do. And sometimes, if we can control the release, but the system itself is not stable, it may only be possible to do one or two cycles of this before the system collapses.”

The research team consists of chemical engineering doctoral student Rong Ma and former chemical engineering doctoral students Dr. Minxiang Zeng, now a research scientist at the University of Notre Dame, and Dr. Dali Huang, now a process engineer at Formosa Plastics Corporation.

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Materials provided by Texas A&M University. Original written by Alleynah Veatch Cofas. Note: Content may be edited for style and length.

The vertical wind tunnel at Johannes Gutenberg University Mainz (JGU), which is the only one of its kind in the world, is providing essential information in this connection through new experiments that are being conducted using artificial hailstones made by a 3D printer. “One thing we have learned so far is that it is the form of hailstones that determines their velocity prior to impact,” explained Dr. Miklós Szakáll of the Institute of Atmospheric Physics (IPA) at JGU. Szakáll’s team has been able to demonstrate that lobed hailstones develop less kinetic energy and thus less destructive potential than hail with a smooth surface.

Hail and graupel, which is the term used to describe precipitated small, soft ice pellets, are formed when water droplets freeze within storm clouds. This freezing process is promoted by turbulences and complex physical processes in these clouds that can extend to very high altitudes. These ice particles melt if they pass through warmer air layers on the way down. The result is large, cold raindrops and these are often the culprits behind extreme rainfall precipitation. Assuming that the ice particles do not have time to melt completely before reaching the ground, they arrive in the form of hail or graupel.

Experiments with natural and artificial hailstones

The conditions in the interior of clouds determine the characteristic form, size, and mass of these frozen droplets. “In our experiments with natural hailstones, we have seen that they melt to form raindrops that can be several millimeters in diameter. Large hailstones can also burst during the melting process, forming numerous small water droplets,” Szakáll added. From the recorded measurements, his team was able to extrapolate parameters that they could use as the main elements for the numerical simulation of clouds and precipitation in computer models.

The research team in Mainz produced hailstones and graupel particles from frozen water in the lab. Employing realistic temperature and humidity conditions, the researchers looked closely at how these fell or melted in the vertical wind tunnel. In addition, they used a 3D printer to create artificial hail and graupel pellets modeled on their natural counterparts — even the material density corresponded with that of ice. They used these to measure the free fall properties of the descending objects, factors that are particularly relevant to the microphysical processes in extreme precipitation events.

The hail and graupel pellets were suspended freely in an artificially produced vertical air stream in the six-meter-high wind tunnel. Their behavior was recorded using high speed and infrared cameras and a specially developed holographic imaging system.

“If we apply the insights into microphysical aspects of precipitation we have obtained through these experiments to models used for the analysis of storm clouds, we can better anticipate what they will do,” explained Professor Stephan Borrmann of the IPA and Director at the Max Planck Institute for Chemistry. “This becomes particularly significant in view of the probable increase in extreme weather events, such as drought and torrential rainfall, that will occur even in our part of the world due to climate change,” emphasized Borrmann.

The experiments in Mainz were undertaken under the aegis of the HydroCOMET project sponsored by the German Research Foundation (DFG). The results have been published in five peer-reviewed journals and as a book contribution.

The experts reviewing the HydroCOMET findings provided very positive assessments of the lab experiments performed in Mainz and the associated publications. They particularly stressed the important role played by the available infrastructure, i.e., the vertical wind tunnel.

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Human pluripotent stem cells (PSCs) are a useful tool for researchers investigating how cells specialise to make every tissue of our body. They come in two different states, primed and naïve. Both types of PSC can self-renew and differentiate into new cell types but they have distinct functions and molecular characteristics.

Group leader Peter Rugg-Gunn explained the importance of these cells: “Human PSCs in the naïve state replicate the key molecular and cellular characteristics of cells in a pre-implantation stage embryo. Importantly, when naïve PSCs are encouraged to self-organise in particular conditions, they form structures that resemble an early blastocyst stage of development. By growing these cells in the lab, we can learn about the key events that happen during human development, and they have potential uses in personalised medicine. But we need to create high-quality, stable stem cell populations to be able to conduct our experiments.”

Pluripotent stem cells are formed either from embryos or using Nobel Prize-winning methods to remove cell identity from specialised cells. The majority of reprogramming experiments generate primed PSCs, which are more developmentally advanced than naïve PSCs. Naïve PSCs can be collected directly from human pre-implantation embryos, or more commonly researchers expose primed PSCs to conditions that induces them to become naïve PSCs. Existing methods for reprogramming were inefficient and slow, preventing researchers’ from quickly producing the numbers of high-quality stem cells they needed.

Adam Bendall, PhD student and a lead researcher on the study, said: “Very little was known about what genetic and epigenetic factors are required for naïve cell reprogramming, and this knowledge gap limited the design of reprogramming conditions.”

The low efficiency of naïve reprogramming suggests the presence of barriers that limit cells in reaching the naïve state. Adam and his colleagues honed in on these barriers by performing a large-scale genetic screen to identify genes that hinder and help reprogramming. They were able to identify a large number of genes that have a crucial role in naïve PSC programming that had not been previously linked to the process.

The team focused on one epigenetic complex in particular, the PRC1.3 complex, that regulates gene expression without altering the underlying DNA sequence, and which they found to be essential for the formation of naïve PSCs. Without this complex, the cells undergoing reprogramming become a completely different type of cell rather than naïve PSCs. This suggests that the activity of PRC1.3 could encourage more cells to reprogram properly, in effect lowering the barrier.

After identifying factors that promote reprogramming, the researchers also looked at factors that impede reprogramming, exemplified in their study by an epigenetic protein called HDAC2. Dr Amanda Collier, first author on the paper, explained: “Excitingly, when we inhibited one of these factors using selective chemicals, then naïve PSC reprogramming occurred more efficiently and rapidly. We’re able to look at it from both sides; we can remove the barriers and introduce the factors that push cells towards state change.”

Not only does this research improve scientists’ ability to produce human naïve PSCs, it provides details on the molecular events that occur during the cell state transition itself, some of which are conserved in developmental regulation in human embryos.

The Rugg-Gunn lab are putting together the pieces of a bigger puzzle — the best understanding of the formation and control of naïve stem cells. Their previous research has identified molecular factors that help to maintain cells in a naïve stage. Group leader, Peter Rugg-Gunn said: “By building up our tools for manipulating pluripotent stem cells, we can spend more time asking important questions about the pre-implantation embryo. In the longer term, further improvements in working with naïve PSCs might open up the possibility for using these cells in personalised disease models or cell therapies, although this will require more research on how to differentiate naïve PSCs into specialised cell types.”

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Materials provided by Babraham Institute. Note: Content may be edited for style and length.

Anyone who enjoys reading thrillers knows: Before thieves break into a mansion, they like to toss a juicy chop over the fence, in which they have hidden a few sleeping pills. When the watchdogs get down to their second dinner, they succumb to deep slumber shortly thereafter. The jewels of the lady of the house change hands much more unperturbed after that.

Tumor cells often proceed in a very similar way: They cast out sleeping pills that paralyze the immune system. More specifically, they surround themselves with a cloud of adenosine, an important endogenous messenger. In this way, they disable the body’s own “killer cells,” which would otherwise cause the cancer cells to die.

This is because the adenosine molecules bind to tiny antennae on the surface of the immune cells, the A2A receptors (the abbreviation stands for “type 2A adenosine receptors”). This knocks out the defensive troops, so to speak. Researchers around the globe are therefore looking for molecules that can block the A2A receptor and prevent the paralyzing effect of adenosine.

Bombardment with X-rays

“Our study should make this search a lot easier,” explains Prof. Dr. Christa Müller of the Pharmaceutical Institute of the University of Bonn. “We have added novel variants of a known inhibitor, a substance called preladenant, to the A2A receptor. Then we created crystals from the receptor-inhibitor complexes — it’s the first time in the world that this has been achieved with preladenant-like substances.”

Crystallization made it possible to elucidate the structure of the complex. “To do this, we bombard the compound with X-rays,” explains Tobias Claff, who performed the main part of the experiments. “The crystal diffracts the rays. The way it does this then allows us to deduce the spatial structure of the complex — right down to the arrangement of individual atoms and their interactions.”

In this way, the researchers were able to show to which points of the A2A receptor preladenant binds. With this knowledge, it is now possible to specifically modify the inhibitor to give it better properties. In addition to having the strongest possible effect, drugs should for example not be broken down too quickly. They also need to be able to reach the place where they are supposed to do their work — in this case, the brain. “Our study will make it much easier to optimize the substance,” Claff says with optimism.

A2A belongs to a group of receptors that regulate key functions in the body. They span the membrane of cells. The part of them that sits on the outside of the membrane serves as a sensor, receiving molecular signals like an antenna. When it does, it triggers specific reactions with its part that protrudes into the cell. This then activates certain genes, for example.

Dye bound to the inhibitory molecule

“These receptors are immensely important because of their central position,” says Christa Müller, who is also a member of the Transdisciplinary Research Areas (TRA) “Building Blocks of Matter” and “Life and Health.” “Many of them, however, are unfortunately relatively unstable. This is unfavorable for X-ray structural analyses — crystallization takes days, sometimes even weeks.” The researchers therefore specifically modified the A2A receptor at a single point, making it considerably more stable.

Additionally, they succeeded in attaching a dye to the preladenant with a kind of molecular string. “This allows us to control where in the tissue preladenant attaches to the A2A receptor,” Müller says. At the same time, the length and flexibility of the nanostring ensures that the inhibitor is not obstructed from binding to the receptor.

Both advances could also serve as models for work with other receptors that belong to the same group. “The methods we have developed in Bonn in recent years will allow us to elucidate the structure of such and other cell membrane proteins in the future,” the pharmacist is convinced. “There aren’t many research facilities that can do this kind of structural analysis of extremely complex molecules.”

Participating institutions and funding:

In addition to the University of Bonn, the Centre for Structural Systems Biology (CSSB) and Forschungszentrum Jülich were involved. The study was funded by the German Research Foundation and the Federal Ministry of Education and Research.