Dr. Shai Bell studies the mechanisms that allow humans to live in healthy relationships with the trillions of bacteria, viruses, and fungi (collectively called the "microbiome") that inhabit the gut, and how disruption of these relationships leads to the development of inflammatory bowel diseases such as Crohn's disease and colitis.

The gut is a complex ecosystem composed of trillions of bacteria, viruses, fungi, and protozoa. This system is collectively called the "microbiome." In a normal state, humans provide microbes with shelter (the gut) and a source of energy (food), while the microbiome contributes to humans by breaking down food and "training" the human immune system. Recently, it has been discovered that the microbiome plays an important role in a variety of health aspects such as obesity, diabetes, autoimmune diseases, and more. Humans keep this bacterial population at a healthy distance from themselves by creating a "militarized" zone consisting of thick mucus and proteins. Antibiotics, which together coat the intestinal tissue like a minefield for bacteria. When this barrier is breached by the infiltration of bacteria, chronic inflammation of the intestine, such as Crohn's disease, may develop, which causes great suffering and deterioration of the patient's general health. Tens of millions of people worldwide suffer from Crohn's disease, and there has been an alarming increase in the number of patients in Israel in recent years. Despite the prevalence of the disease, the causes of its development are unknown, as are effective methods of treating it. Dr. Shai Bell's laboratory is studying how the body maintains the "militarized" area despite attempts by bacteria to penetrate, why this area may be breached, and why during Crohn's disease this area does not regenerate and inflammation occurs. The laboratory uses innovative tools such as genetically modified mice, modern microscopy, and RNA sequencing, to unravel why inflammatory bowel diseases develop and how they can be treated.