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- Title
An Integrated In Vitro Imaging Platform for Characterizing Filarial Parasite Behavior within a Multicellular Microenvironment.
- Authors
Kassis, Timothy; Skelton, Henry M.; Lu, Iris M.; Moorhead, Andrew R.; Dixon, J. Brandon
- Abstract
Lymphatic Filariasis, a Neglected Tropical Disease, is caused by thread-like parasitic worms, including B. malayi, which migrate to the human lymphatic system following transmission. The parasites reside in collecting lymphatic vessels and lymph nodes for years, often resulting in lymphedema, elephantiasis or hydrocele. The mechanisms driving worm migration and retention within the lymphatics are currently unknown. We have developed an integrated in vitro imaging platform capable of quantifying B. malayi migration and behavior in a multicellular microenvironment relevant to the initial site of worm injection by incorporating the worm in a Polydimethylsiloxane (PDMS) microchannel in the presence of human dermal lymphatic endothelial cells (LECs) and human dermal fibroblasts (HDFs). The platform utilizes a motorized controllable microscope with CO2 and temperature regulation to allow for worm tracking experiments with high resolution over large length and time scales. Using post-acquisition algorithms, we quantified four parameters: 1) speed, 2) thrashing intensity, 3) percentage of time spent in a given cell region and 4) persistence ratio. We demonstrated the utility of our system by quantifying these parameters for L3 B. malayi in the presence of LECs and HDFs. Speed and thrashing increased in the presence of both cell types and were altered within minutes upon exposure to the anthelmintic drug, tetramisole. The worms displayed no targeted migration towards either cell type for the time course of this study (3 hours). When cells were not present in the chamber, worm thrashing correlated directly with worm speed. However, this correlation was lost in the presence of cells. The described platform provides the ability to further study B. malayi migration and behavior. Author Summary: Lymphatic Filariasis is the largest world-wide source of secondary lymphedema and is caused by parasitic nematodes that migrate to and dwell in the lymphatic system. The World Health Organization estimates that over 120 million people in 73 countries are currently infected, and a further 1.4 billion live in infection-prone areas. Infection is initiated when a mosquito deposits infective larvae on the skin of the human host. The larvae then penetrate the skin at the site of the bite and migrate to afferent lymphatic vessels feeding into lymph nodes, where they mature into adult worms. While a large portion of infected individuals remain asymptomatic, many individuals show signs of potent immune responses that result in diseases such as lymphedema, elephantiasis and hydrocele. Through mass drug administration it is possible to kill the microfilariae stage of the parasite, which is the infective form for the mosquito intermediate host. There are currently no proven treatments for the adult worm, thus making it difficult to treat the estimated 120 million people already infected. Understanding how and why these parasites migrate to and reside in the lymphatic system will further aid researchers in designing treatment strategies that interrupt this mechanism. Here we describe an in vitro platform that allows researchers to quantify the migration behavior and the effects of drugs while maintaining the worm in the presence of cells typical of the host infection site.
- Subjects
WORLD Health Organization; NEGLECTED diseases; LYMPHATICS; TEMPERATURE control; HELMINTHS; ANTHELMINTICS; TREMATODA
- Publication
PLoS Neglected Tropical Diseases, 2014, Vol 8, Issue 11, p1
- ISSN
1935-2727
- Publication type
Article
- DOI
10.1371/journal.pntd.0003305