The primary focus of my laboratory at Vanderbilt is inflammation, a biological response that links innate and adaptive immunity to blood kinins and coagulation networks.
Inflammation comes from the Latin word "Inflammatio" which means to set on fire. It is ironic that this protective response to remove harmful stimuli from the body in order to initiate healing is also the main mechanism of diseases caused by microbial, autoimmune, metabolic, and physical factors. In fact, approximately 80% of all major human diseases, including heart attacks, strokes, sepsis, and early cancer, are mediated by inflammation.
Proinflammatory cues are sensed by pattern recognition receptors such as Toll-like Receptors (TLRs) that are mainstays of innate immunity. These receptors generate signals that are transduced to the nucleus by an intricate network of intracellular adaptors. We study two families of these adaptors as potential targets for anti-inflammatory therapy to prevent reprogramming of the genome toward proinflammatory phenotype.
The first family of innate immunity adaptors of intense interest is MyD88 (myeloid differentiation 88) protein and its four relatives, including MAL, TRIF and SARM. We study them by identifying their cross-talk with TLRs and with each other. For example, we identified the RDR motif in Box 2 of MyD88 TIR domain as the interactive site with some members of TLR superfamily. This site is mutated in inborn errors of innate immunity characterized by pyogenic infections. We also unraveled a new function for another adaptor SARM.
The second family of adaptors of longstanding interest to us is the so-called nuclear import machinery, known as importins or karyopherins. We provided initial evidence that by targeting them with cell-penetrating peptides, which displace nuclear import cargo from its binding pocket on importin alpha 1, we prevent nuclear delivery of proinflammatory transcription factors such as NFkappa B, AP-1, NFAT, and STAT-1. Hence, proinflammatory reprogramming of the genome is prevented in multiple cells that stop producing inflammatory, procoagulant, proapoptotic, and autoimmune mediators. We accomplished this outcome by developing an innovative platform for intracellular delivery of peptides and proteins that bypass endosomal pathway with its degradative potential. We have proven the utility of nuclear import inhibitors as cell-penetrating peptides in preclinical models of septic/toxic shock and in acute lung inflammation caused by bacterial lipopolysaccharide and superantigen as well as in chronic autoimmune diabetes model that mimics Type 1 diabetes. We extended these long-term treatment studies to a relevant model of atherosclerosis induced by Western diet in LDL receptor-negative mice. Cumulatively, these basic and translational studies provided a firm basis for the nuclear paradigm of inflammation.
Finally, we continue our groundbreaking studies of intracellular protein therapy as a facile alternative of gene therapy. We have proven the utility of intracellular protein therapy by bioengineering and delivering physiologic suppressor of cytokine signaling 3 (SOCS3) to prevent or treat acute liver inflammation and apoptosis induced by microbial agents in preclinical models. We extended the anti-inflammatory action of cell-penetrating SOCS3 by engineering its long-acting form to persist 41 times longer than endogenous SOCS3. This increased stability, coupled with the capacity for rapid intracellular delivery renders the CP- SOCS3 mutant an attractive candidate for intracellular protein therapy to suppress acute and chronic inflammation induced by a variety of proinflammatory agonists in multiple organ systems.