The Knight Lab has historically been a B cell laboratory focused on how the B cell arm of the immune system contributes to health and disease. More recently, we have expanded our interests to include host-microbe interactions, specifically as it relates to the mechanism by which molecules from probiotic bacteria induce anti-inflammatory reactions and protect from disease. We are also developing a mucosal vaccine to protect from intestinal disease caused by Clostridium difficile infection, and investigating monocyte regulation of infant immune responses.

B lymphocyte development

Exposure of individuals to foreign antigens, such as those associated with bacteria and viruses, results in production of thousands of different antibody molecules. My laboratory is interested in how organisms develop such a large and diverse array of antibodies during development of B lymphocytes in the bone marrow and how intestinal microbiota contribute to this process in gut-associated lymphoid tissues. B cells develop from stem cells in the bone marrow, and we find that with age, the generation of B cells arrests, and almost no new B cells develop. Our studies are focused on determining the mechanism by which B lymphopoiesis arrests. We hypothesize that the arrest is due to an increase in the number of adipocytes which secrete inhibitory molecules. We have found molecules from adipocytes that inhibit B lymphopoiesis in vitro, and our goal is to identify and characterize these molecules and determine the mechanism by which they inhibit B lymphopoiesis. For this project, we use bone marrow cells and adipocytes from humans, rabbits, and mice and study them using tissue culture techniques, flow cytometry, protein and lipid biochemistry, and RT-PCR.

Host-microbe interactions- the use of probiotic bacteria to prevent disease

We identified a commensal bacteria that can protect the host from disease caused by pathogenic organisms, specifically Citrobacter rodentium, a bacterium that causes a disease in mice similar to Traveler’s Diarrhea caused by enteropathogen Escherichia coli in humans. We found that a single oral dose of spores from the common bacterial species, Bacillus subtilis can protect mice from intestinal disease caused by C. rodentium. B. subtilis induces a protective anti-inflammatory host response and our goal is to determine the mechanism by which B. subtilis protects from disease caused by C. rodentium. We have identified and purified the bacterial molecule from B. subtilis that provides protection in vivo, and we are searching to identify the cells and molecular pathway by which this anti-inflammatory molecule functions. This bacterial molecule also prevents the development of food allergy in mice, and we are investigating the mechanism by which this occurs. For our investigations, we use normal and gene-specific knock-out mice in combination with cell culture techniques, flow cytometry, ELISA, western blots, and immunochemical methods. Mucosal vaccine for Clostridium difficile The major hospital-acquired infection in the U.S. is caused by the enteric pathogen Clostridium difficile which leads to untold misery from colitis. We are using pseudoviruses as a platform for a protective mucosal vaccine to prevent disease caused by C. difficile. For this investigation, we use recombinant DNA techniques, cell culture techniques, ELISA, and immunochemical methods.

Monocyte regulation of infant immune responses

Working with Dr. Makio Iwashima, we are searching for a means of enhancing immune responses of infants, making them less vulnerable to infectious agents. We are examining a subset of immunosuppressive monocytes to determine if these are responsible for a low level of immunity in infants and we are searching for a means to attenuate this immunosuppression.

 Knight Lab 2015