Shedding Light on Chagas Disease
Trypanosoma cruzi (T. cruzi) is a protozoan parasite that causes Chagas disease. T. cruzi is transmitted to humans through the feces of bloodsucking insects in endemic areas of Latin America. Chagas disease is a growing health concern in the United States and other countries with large Latin American immigrant populations. Two of the major concerns are the misdiagnosis or failure to diagnose Chagas' heart disease and the possibility of transmission of the disease through blood transfusion or organ transplantation.
The laboratory of Huan Huang, MD, studies the molecular biology of T. cruzi, the pathogenesis of Chagas disease, and genetic techniques. Their research holds promise for therapeutic drug development.
Dr. Huang and his group study the protein kinases and kinase signaling pathways in T. cruzi, identifying and characterizing components in cAMP-dependent protein kinase (PKA) and mitogen-activated protein kinase pathways in T. cruzi. They also investigate the role of infection-related damage in cardiac microvasculature and parasite-derived Thromboxane A2 in pathogenesis, and are exploring resolvins as a potential therapeutic agent for Chagas disease.
The Huang lab has advanced molecular genetics in T. cruzi by designing a modified pTREX vector that uses an N-terminal fusion of a ligand-controlled destabilization domain (ddFKBP) to a gene/protein of interest. This vector system allows rapid and reversible protein expression and efficient functional analysis of proteins in different T. cruzi life-cycle stages. These transgenic T. cruzi are being used to understand disease mechanism(s) underlying chronic T. cruzi infection. Furthermore, these transgenic T. cruzi strains induce strong protection against re-infection in mice providing a tool to understand an effective immune response for protection against T. cruzi infection.
Investigating Toxoplasmosis
Toxoplasma gondii (T. gondii), an opportunistic pathogen, infects more than 1 billion people worldwide. The majority of infected individuals live asymptomatically and host this obligate intracellular parasite in its latent encysted life cycle. However, immune-compromised individuals have high risk of developing reactivation of latent toxoplasmosis, including symptoms such as retinochoroiditis, encephalitis and pneumonitis. Although clinical drugs are available for treating toxoplasmosis, they mainly target tachyzoites, the rapidly replicating stage of the parasite. To date, no effective treatment exists for eliminating latent parasites, or bradyzoites, from the human body. To develop treatment to target and eradicate bradyoites from the host, it’s crucial to learn more about the latent-stage biology of this parasite.
One characteristic of the latent stage of T. gondii is the presence of a thick cyst wall that forms underneath the parasitophorous vacuole membrane. Currently, the function of the cyst wall and the process of how T. gondii establishes this structure remains largely unknown. Under the direction of Louis M. Weiss MD, MPH, the Parasitology Research Laboratory is investigating the T. gondii cyst wall and mechanism(s) of latency in this chronic infection. They have developed techniques to purify the cyst for proteomic analysis and are using molecular biology tools to further define the composition of this structure, the interactome of the various proteins found in this structure, and the role of these proteins in formation of the cyst wall.
Revealing the Structure of Microsporidia: emerging opportunistic pathogens
Microsporidia are intracellular pathogens transmitted by food and water that cause infection in patients with AIDS. They infect cells using a unique specialized invasion organelle, the polar tube. Infection occurs in the gastrointestinal, ocular, reproductive, respiratory, muscle, excretory and nervous systems. The approximately 200 genera and 1800 species of Microsporidia parasitize a wide range of invertebrate and vertebrate hosts, including humans. They are important parasites in HIV and other immune-compromised patients, and can also infect immune-competent humans as well as insects, fish, mammals and birds.
Using a combination of proteomic and cell biology approaches, the laboratory of Louis M. Weiss MD, MPH is investigating the function and composition of the polar tube, spore coat and polaroplast, which make up the invasion organelle of these pathogens. Despite its description as a morphologic structure over 100 years ago, the full complement and interactions of the proteins making up this structure, the mechanism of its formation during invasion, and the cell biology underlying its formation are still not understood. Dr. Weiss and his team aim to define the invasion organelle, its proteome and interactome. Their goal: to provide new insights into the polar tube’s structure, dynamics and organization and shed light on the mechanism(s) of host cell invasion by these organisms.
The morbidity and overall disease burden associated with microsporidiosis can be significant; for example, microsporidian diarrhea in the AIDS patients is associated with a significant increase in mortality.
Methionine aminopeptidase type 2 (MetAP2) is a highly validated target for treatment of microsporidiosis. Microsporidia lack MetAP1, making MetAP2 an essential enzyme for the microsporidia. Among eukaryotes this makes them highly susceptible to MetAP2 inhibitors and limits the toxicity of these compounds in their hosts. Use of fumagillin and its derivatives, which covalently bind to and inhibit MetAP2 (but not MetAP1), has confirmed that inhibition of MetAP2 is an effective in vitro and in vivo therapeutic target for many species of microsporidia. The Weiss Laboratory has cloned, expressed and determined the crystal structure of the microsporidian Encephalitozoon cuniculi MetAP2 (i.e. EcMetAP2) and has developed Saccharomyces cerevisiae dependent on Ec MetAP2 for growth. In collaboration with Dr. Bhaskar Das at Mount Sinai they are developing (using a Limited Rational Design approach) and testing new competetive inhibitors of MetAP2 with increased selectivity for microsporidia.