We study host-pathogen interactions. Specifically, we are interested in how the infection of pathogens including viruses and bacteria triggers or inhibits the host innate immune signaling pathways, and how this affects the development of infectious diseases.

Invading viruses and bacteria usually contain pathogen-specific molecules that can be recognized by host receptors named pattern recognition receptors (PRRs). This will activate a series of signaling cascade and eventually lead to activation of cytokines (including type I interferons, IL-1β, IL-1α and many others) and chemokines. In some pathways this also results in proinflammatory cell death.

These innate immune responses are critical for the host organisms to clear the invading microbes. And this is why many pathogens have evolved different strategies to counter the innate immune signaling pathways. On the other hand, proinflammatory responses can lead to pathogenesis in many infectious diseases, such as cytokine release syndrome in viral infections and septic shock in bacterial infections. Without proper treatment, this can lead to multiple organ failure and even death in patients.

Sometimes the innate immune and inflammation signaling can be activated even in the absence of infections, which is a strong contributor to a number of human health problems including autoimmune diseases, cancers and neurodegenerations.

We’re particularly interested in inflammasomes, which are multi-protein complexes responsible for the induction of proinflammatory cytokines and inflammatory cell death. The NLRP3 inflammasome pathway is unique in innate immune signaling because it can be triggered by a plethora of diverse signals from both pathogens and environmental danger. Our recent work has uncovered the unexpected role of trans-Golgi network dispersion in NLRP3 inflammasome activation, and we are currently studying how pathogens including viruses and bacteria are able to remodel this host subcellular organelle, and how it affects both host defense and pathogenesis in infectious diseases.

Another major direction of our lab is to study the functions of organelle remodeling in viral and bacterial pathogenesis. Our recent work discovered a novel type of membrane structures assembled during SARS-CoV-2 infection, which we named the 3a dense bodies (3DBs): 

• 3DBs have unusual electron-dense and dynamic inner structures.

3DBs in overexpression system:

3DBs in infected cells:

• The ability of ORF3a to form 3DBs is conserved in bat coronaviruses, yet lost during the evolution to SARS-CoV.

• 3DB formation is controlled by 7 key residues. Mutating these residues specifically disrupts the ability of ORF3a to form 3DBs in recombinant SARS-CoV-2 (rSARS-CoV-2).

• 3DBs recruit the structural proteins S and M and significantly enhanced the viral infectivity.

 

Our lab utilizes diverse and complementary approaches to study these problems, including biochemical assays, high-resolution fluorescence imaging with our in-house confocal microscope, CRISPR knockout/rescue technology and mouse models. Part of our lab is stationed at the Howard Taylor Ricketts Laboratory, a BSL3 level facility belonging to the University of Chicago, where we study SARS-CoV-2 pathogenesis using cell and mouse infection models.