Highlights from the Pharmaceutical Sciences’ Departmental Research Day

The Department of Pharmaceutical Sciences at the University of Antwerp recently showcased the innovative research of its Ph.D. students during their annual departmental research day. This event highlighted a diverse array of projects, reflecting the department’s commitment to advancing scientific knowledge and improving public health. From exploring the potential of novel small molecules in targeting DPP9 to developing antimicrobial coatings for medical devices, our Ph.D. students are pushing the boundaries of Pharmaceutical Sciences.

Joni De Loose: Lighting up DPP9 Using Novel Small Molecules

Dipeptidyl peptidase 9 (DPP9) is an enzyme that plays a pivotal role in the human immune response. Deleting DPP9 in specific cells triggers a mechanism leading to cell death. As DPP9 is crucial for cell survival, it presents an intriguing potential drug target, for instance, in the battle against HIV-1. However, for an enzyme to be effectively targeted by drugs, its biological functions must be well characterized. In the Department of Pharmaceutical Sciences, we combine our knowledge and expertise to study DPP9 and contribute to unraveling its role in human cells.

We tested how novel chemical molecules that block DPP9 affect the viability of human blood cells. By isolating white blood cells from healthy volunteers, we discovered that these cells do not survive when DPP9 is inactive. We found differences in effects between blood donors, suggesting that DPP9 biology may vary among individuals. To further investigate this, we visualized DPP9 in various white blood cells, including monocytes, macrophages, and dendritic cells. We observed that DPP9 can be present in different cellular compartments, which may contribute to the variability between blood donors. In some donors, cells expressed DPP9 predominantly in the cytoplasm, whereas in others, nuclear DPP9 was observed. As very little is known about DPP9’s role in the nucleus, this work highlights the importance of illuminating DPP9’s nuclear function in future research.

In conclusion, our findings demonstrate that DPP9 is a key player in white blood cells. Using novel chemical molecules that target DPP9, we have taken a significant step towards understanding the therapeutic potential of this complex protein.

Callan Wesley: Innovative Techniques to Measure Arterial Stiffness and Ensure Drug Safety

In drug development, safety is crucial. We want to ensure that drugs do not cause harmful effects on the heart and blood vessels. One way to assess this is by measuring how stiff the arteries are, which can indicate a risk for heart problems. Traditionally, we’ve looked at metrics such as blood pressure and heart rate, but these don’t provide the whole picture. Arterial stiffness, which reflects the rigidity of the arteries, can be a more comprehensive indicator.

We have developed new methods to measure arterial stiffness both inside and outside the body. These techniques help us to understand how drugs may affect artery stiffness directly, without being influenced by other factors such as blood pressure and heart rate. This toolbox of techniques not only allows us to assess the immediate effects of drugs but also aids in studying long-term changes in blood vessel health.

We’re particularly interested in how a certain class of antibiotics, called fluoroquinolones, may affect artery stiffness. These antibiotics have been linked to serious tendon injuries, and there is concern that they may also harm blood vessels. To investigate this, we are combining data from large medical databases with experiments on animals to see if there is a connection between these antibiotics and blood vessel problems.

Milan Wouters: Battling Biofilm in Ventilator-Associated Pneumonia: Developing Antimicrobial Coatings on Endotracheal Tubing

Hospital-related infections remain a major problem worldwide, with many linked to medical equipment such as artificial heart valves, urinary catheters, or implants like hip replacements. According to previous studies, lung infections (pneumonia) are among the most common hospital-acquired infections. Notably, 96% of these hospital-acquired pneumonia episodes are associated with intubation of mechanically ventilated patients and are classified as ventilator-associated pneumonia (VAP). VAP drastically increases mortality, with Pseudomonas aeruginosa being the most common causative organism.

Given the importance of preventing VAP over treating it, we aim to develop an antimicrobial coating for intubation tubes. Using a preventive coating with common antibiotics in everyday clinical practice could lead to overexposure and drug resistance, so a novel coating with antimicrobial proteins was explored. The coated tubes were analyzed in a laboratory environment for their antimicrobial activity, and their mechanical characteristics were examined at the University of Technology in Warsaw, Poland. This initial coating, based on the commercially available protein polymyxin B, which is active against P. aeruginosa, served as a methodological example for developing protein-based coatings. The protein was attached to the tubing through two different approaches, one more successful than the other.

The first approach involves polydopamine (PDA), a biological substance known to enhance attachment to various surfaces. PDA is a commonly used coating component because it is non-toxic and easy to apply. The coating process involves attaching its precursor, dopamine, onto the plastic substrate, which for intubation tubes is typically polyvinyl chloride (PVC). The polydopamine layer is then formed under the correct acidity and oxygen levels. Subsequently, the desired protein can be linked with this layer through chemical interactions, resulting in an antibacterial coating on the surface.

The second approach centers around incorporating polymyxin B into a hydrogel on top of the plastic surface. The main advantage of this approach is the controlled release of the protein from the produced hydrogel, which makes the coating active over several days or weeks. During the production process, the base layer was first activated using different chemicals to facilitate gel attachment to the surface. The gel was then formed via ultraviolet light illumination, and finally, the protein was incorporated into the gel. Various analyses were performed to confirm the coating on the tubes. High-end microscopy was used for visual validation next to the generation of 3D images that clearly show the coating. The release of polymyxin B from the gel was determined, combined with several antibacterial assays. Lastly, the coating was further mechanically analysed by looking at its roughness.

Olivier Beyens: Computational Design of Novel DPP8 and DPP9 Inhibitors Using Cosolvent Molecular Dynamics Simulations

We apply a type of computer simulation called “cosolvent molecular dynamics” to three enzymes: DPP4, DPP8, and DPP9. You can imagine an enzyme as a small factory inside our body. One of these enzymes, namely DPP9, causes a certain type of cancer cells to die when its normal operation is stopped by a molecule. Stopping the normal operation of an enzyme is called inhibition, and molecules that cause this inhibition are called inhibitors. As DPP9 inhibition causes certain cancer cells to die, designing DPP9 inhibitors is potentially interesting for developing new cancer therapies. The goal of our computer simulations is to aid in designing what these inhibitor molecules should look like.

The other two enzymes, DPP4 and DPP8, are very similar to DPP9, which is why we included them in our analyses. Furthermore, the functions of DPP8 are still being researched. Better-designed inhibitor molecules for DPP8 can help accelerate research on the biological roles of DPP8. Currently, there is a limited availability of molecules that inhibit DPP8 without also inhibiting DPP9.

How can these computer simulations help with the design of better inhibitor molecules? We start with the structure of the enzyme and place it in a virtual box. This virtual box is then filled with water molecules, ions, and small chemical fragments. Following this setup, the movement of all individual atoms is calculated. By analyzing this simulation, we can see where the small chemical fragments tend to reside within the enzyme structure, generating chemical fragment affinity maps. If we choose the small chemical fragments to represent those often used in drug molecules, these calculated fragment affinity maps can help researchers decide where to place specific chemical fragments to design potent inhibitors. We have calculated such fragment affinity maps for DPP4, DPP8, and DPP9, and we will make these freely available to other researchers to assist with their inhibitor design.

Lidia Belova: Identification of Quaternary Ammonium Compounds (QACs) and Other Environmental Contaminants in Indoor Dust Samples

Quaternary ammonium compounds (QACs) are substances commonly used in sanitizing and cleaning products and can also be found in pharmaceuticals used for wound disinfection. The COVID-19 pandemic has led to a substantial increase in the use of QACs, resulting in a higher risk of human exposure to these compounds. This exposure can lead to various toxic effects, such as hypersensitivity reactions and an increased risk of asthma. Excessive use of QACs can also contribute to the growing problem of multi-resistant bacteria. A recent study quantified 19 QACs in indoor dust samples collected in the United States, observing significant increases in QAC concentrations between samples collected before and during the COVID-19 pandemic. Ingestion of dust was identified as an important factor leading to human exposure to these compounds. However, studies on the occurrence of QACs in European dust samples are lacking.

My research focuses on developing analytical methods to identify QACs and other classes of contaminants in dust and other environmental samples. We use ion-mobility high-resolution mass spectrometry, a technique that measures the exact mass of an analyte and its mobility through a buffer gas, correlating to the analyte’s molecular shape. This allows us to simultaneously identify numerous known and novel contaminants that might be overlooked by other common analytical techniques.

We applied this methodology to identify QACs in 46 indoor dust samples collected in Flanders. In these samples, 21 known QACs were found and confirmed with corresponding reference standards. Additionally, we identified 17 novel QACs, revealing new classes of these compounds. Our method also allowed us to estimate the concentrations of both known and novel QACs. From these concentrations, we can assess human exposure to QACs based on the estimated daily dust ingestion. For none of the identified QACs did the estimated exposure indicate a potential health risk. Nevertheless, the high number of new QACs highlights the variability of these compounds in indoor dust. In the same samples, a parallel study identified several other contaminant classes, with plastic-related chemicals (phthalates) and flame retardants being the most abundant. This clearly identifies dust as a relevant source of human exposure to numerous environmental contaminants, pointing out the most relevant classes that should be further assessed in future studies.

Stef Lauwers: Do Elderly People Digest Healthy Olive-Based Products Differently?

As people live longer, caring for the elderly is becoming increasingly important. Maintaining health in old age is now a top priority. Research shows that following the Mediterranean diet, which includes foods rich in antioxidants such as polyphenols, can lower the risk of heart disease. Olive-based products, fundamental to this diet, contain polyphenols like oleuropein and hydroxytyrosol, known for their antioxidant properties.

These polyphenols are chemically modified by the bacteria in our gut. Since our gut bacteria change as we age, the way our bodies process polyphenols might differ between younger and older individuals. To study this, a lab model mimicking the human digestive system was used to test how polyphenols from olives are transformed in both healthy young and healthy elderly people. We found that both age groups broke down the polyphenols in similar ways, producing the same products.

In conclusion, even as we age, our bodies can still benefit from the health-promoting effects of polyphenols found in foods like olives.