How spectral flow cytometry is advancing understanding of the gut immune system’s role in IBS

Dr. Hind Hussein, postdoctoral researcher, is part of the Intestinal Neuroimmune Interactions lab of KU Leuven that is investigating how the intestinal nervous and immune systems interact, and how a disruption in this interaction may lead to irritable bowel syndrome (IBS).

The burden of irritable bowel syndrome

IBS is a chronic and painful condition that can severely affect a person’s quality of life, especially as there are currently no effective treatments. TARGID, the Translational Research Center in Gastrointestinal Disorders of KU Leuven, Belgium, aims to provide insights into the physiological and pathophysiological mechanisms underlying gastrointestinal disorders. The lab of Intestinal Neuroimmune Interactions, led by Prof. Guy Boeckxstaens, investigates IBS and strive to shed light on this condition, paving the way for the discovery of novel therapeutic targets and advancements in treatments.

IBS is estimated to affect between 2 and 15% of the global population, most commonly young women. It is characterized by symptoms including abdominal pain, bloating, diarrhea, constipation, and flatulence. These symptoms can come and go, with flare-ups often triggered by stress, or eating certain types of food. For many people, IBS is a lifelong condition, and the discomfort can have a significant negative impact on everyday life.

The human gut is lined with millions of nerve cells that make up the enteric nervous system (ENS) which modulates digestion and enables communication with the brain. IBS patients are believed to have overly sensitive pain-sensing nerves in the gut. When individuals with IBS consume food, the expansion of their gastrointestinal tract causes the activation of pain-sensing nerves, which leads to pain in addition to other IBS symptoms highlighted above. Additionally, because the ENS is linked to the brain, IBS is also closely associated with psychological conditions – such as anxiety and depression – as it is believed to disrupt the crosstalk between the central nervous system (CNS) and the ENS.

“Confusingly for scientists, and unlike other intestinal disorders like Crohn’s disease or colitis, intestines of IBS patients appear to be healthy, and the underlying causes of the condition are still not fully understood,” Hussein explains. “As a result, there are currently no effective treatments targeting pain in IBS, which means that many people are unfortunately left suffering and have to manage their symptoms through lifestyle strategies such as altered diets.”

“However, even though IBS patients’ intestines appear fine, my team recently discovered that their intestinal immune system is disrupted, which we believe could cause the condition to develop,” continues Hussein. “This was a huge breakthrough for IBS research and I am now pursuing this discovery to better understand what exactly goes wrong with the intestinal immune system of IBS patients, when it occurs, and why it happens. Most importantly, our ultimate goal is to identify if there is any way we can treat IBS, and particularly abdominal pain, by restoring the intestinal immune system.”

Hear how Dr. Hind Hussein is working to elucidate intestinal neuro-immune interactions with spectral flow cytometry >>

The importance of spectral flow cytometry in IBS research

Hussein and her team use flow cytometry to characterize and quantify immune cells in the gastrointestinal tract and investigate the intricate interactions between the nervous and immune systems in people with IBS. This technique involves tagging markers with fluorochromes which emit light at specific wavelengths when excited, creating a spectrum of emission.

With conventional flow cytometry, the emitted light is analyzed in chunks by detectors in the flow cytometer, providing information about the types of cells present in a sample and their properties. However, conventional flow cytometry is limited because the entire spectrum of emission cannot be analyzed at once. This means multiple sample panels must be developed which is especially difficult when examining the gut, as tissue samples are limited.

The use of more advanced flow cytometry technology, such as spectral flow cytometers, can help overcome these challenges and provide more comprehensive cell analysis. These instruments enable scientists to analyze the entire spectrum and facilitate the simultaneous examination of multiple markers, minimizing the number of samples needed.

Dr. Hussein uses the ID7000™ Spectral Cell Analyzer by Sony Biotechnology, which has allowed her and her team to make significant progress with their research whilst considerably reducing the effort, time, and resources required for each experiment when compared to conventional flow cytometry.

“This technique is life-changing for me and has been particularly helpful for studying innate cells, such as macrophages, as the ID7000 flow cytometer has the capability to unmix the autofluorescence of these cells – I thought macrophages would be my archnemesis, but thanks to this technology, I am now even growing to like them!”

The evolution of spectral flow cytometry

Spectral flow cytometry is still a relatively new technology that has recently started gaining momentum in research fields such as drug development and disease research. “It is fascinating to have witnessed the evolution of flow cytometry during my seven years of research on the gut,” shares Hussein. “During my studies, I worked with instruments that only allowed a maximum of 8 colors, progressing to 21 colors towards the end of my Ph.D.”.

Hussein highlights how this marked a substantial shift in how researchers approached scientific investigations, requiring the design of more efficient panels and combinations of markers. “When I first moved to TARGID, they used 21-color conventional flow cytometers but soon introduced the ID700 spectral flow cytometer with over 44 colors, which has completely transformed our research,” states Hussein.

While there may be a slight shift in mindset when transitioning from conventional to spectral flow cytometry, the underlying principles remain the same. Hussein believes embracing spectral flow cytometry is undoubtedly the way forward, providing a more informative and advanced approach. “New technologies are currently focused on coupling the advantages of spectral flow cytometry and microscopy, which would allow us to not only pick up the signal that is emitted but also the location of the signal at the cell level,” explains Hussein. “I am excited to see how new technologies will shape my research and what spectral flow cytometry will uncover in other research fields as it becomes more popular,” concludes Hussein. “I highly recommend other researchers transition to using Sony’s ID700 spectral flow cytometer as it offers numerous advantages over conventional flow cytometry. Most importantly, it provides more clear, accurate, and comprehensive data, which reduces the chances of misinterpreted or unreliable results that can halt research progress. There is no compelling reason to cling to conventional flow cytometry when the benefits of spectral flow cytometry are evident.”