Tiffany Borbon successfully defends PhD thesis

On December 17, 2018, Tiffany Borbón successfully defended her thesis titled "A Bacterial Coinfection during Murine Cutaneous Leishmaniasis." She is pictured with her mentor Dr. Mary PhD student Tiffany Lim Borbon with Dr. Mary WilsonWilson.


Cutaneous leishmaniasis is a vector-borne ulcerating skin disease that affects over 12 million people worldwide. The causative Leishmania species parasites are transmitted by infected phlebotomine sand flies. Most Leishmania spp. infections are asymptomatic, and the factors that lead to symptomatic infection are not fully understood. When a sand fly takes a blood meal, bacteria can be inoculated into the dermis with the parasite. Staphylococcus aureus is the most common bacterium in cutaneous leishmaniasis lesions. The effects of bacterial coinfection with Leishmania on the host immune system are largely unknown. We hypothesized that local bacteria influence the formation and severity of lesions that develop at the site of Leishmania spp. infection.

Using a mouse model of cutaneous leishmaniasis, we discovered that lesions are more severe in mice receiving S. aureus simultaneously with L. major in the skin than in mice infected with either organism alone. Although L. major burden was not affected, lesion exacerbation during coinfection correlated with an early increase in S. aureus burden, more neutrophils, and greater levels of two cytokines, IL-1b and IL-17A, which promote inflammation. Importantly, most of the neutrophils recruited within the first day of coinfection were apoptotic, and efferocytosis was downregulated, which may account for transiently elevated S. aureus burdens. Neutralizing antibody experiments suggested IL-17A was partially responsible for lesion exacerbation during coinfection, whereas IL-1b is important for control of early lesion exacerbation. Our study provides new insights into the effects of bacterial coinfection on the immune response to Leishmania spp. and may contribute to novel approaches for reducing the severity of cutaneous leishmaniasis disease.


Tiffany was born and raised in Seattle, WA as the middle child of Kim-Fu and Silvia Lim. Growing up, Tiffany enjoyed playing the piano; participating in several different sports, including gymnastics and tennis; and reading fiction novels after her older brother, Chris, and little sister, Natasha, finished speeding through them. Her interest in science and medicine began early in childhood, when her parents and grandmas would often find her playing with her model skeleton, reading books about microbes and the human body, pretending to be a doctor, or playing with worms in the backyard.

After high school, Tiffany enrolled in the Academy for Young Scholars at the University of Washington (UW) to pursue a degree in Microbiology while fulfilling pre-med requirements. In preparation for medical school, Tiffany volunteered at the Seattle Children’s Hospital and joined the lab of Dr. E. Peter Greenberg as an undergraduate researcher, studying a form of bacterial cell-to-cell communication called quorum sensing. It was in Dr. Greenberg’s lab that Tiffany gained a passion for scientific research as a means of helping many people, particularly in the field of infectious diseases.

Upon graduating from UW, Tiffany worked for a year at the Tri-Service Research Facility at Fort Sam Houston, TX as part of the Science, Math, and Research for Transformation Scholarship-for-Service Program funded by the Department of Defense. There, she made many wonderful friends, learned a lot about research in a new setting, and realized that she truly wanted to become a physician scientist.

In 2012, Tiffany joined The University of Iowa Medical Scientist Training Program and enrolled in the Department of Microbiology graduate program in 2014. She has worked under the mentorship of Dr. Mary E. Wilson on understanding the impact of bacteria on the host immune response to Leishmania major in a murine model of cutaneous leishmaniasis.

Outside of the lab, Tiffany enjoys traveling and hiking with her husband, Daniel, and visiting family and friends all over the world. She also enjoys cross-stitch, playing piano at church, meeting other people’s pets, and having a good conversation over a meal or on a walk with friends and family.



Tuesday, December 18, 2018