PhD Candidate: Mary Wilson
Abstract
Leishmaniasis is a group of diseases caused by the parasitic protozoa belonging to the genus, Leishmania. Visceral leishmaniasis (VL) is the severest of the syndromes, causing the majority of fatalities due to leishmaniasis. The disease is usually vector-borne, caused by a bite from a female phlebotomine sand fly. Consequently, the disease is prevalent in endemic regions in which infected sand flies have contact with humans. The regions of the world where symptomatic visceral leishmaniasis occurs most commonly include Brazil, adjoining regions of India/Bangladesh/Nepal, and countries in eastern Africa. A majority of cases are asymptomatic, leading us to question what host factors predispose to developing symptomatic VL. Our collaborators in Varanasi, India purified CD4+ T-cells and CD14+ phagocyic cells from peripheral blood or bone marrow of twelve patients with VL, prior to treatment. In parallel, blood and bone marrow CD4+ or CD14+ cells were collected from twelve subjects from the same region of India who underwent diagnostic bone marrow aspirates for other purposes. Final diagnoses of control subjects were not available until the data processing step. These ultimately showed control subjects had a variety of disorders including two with chronic myelocytic leukemia and one with acute myeloma. RNA was extracted and underwent paired end sequencing. The reads from CD14+ cells were aligned to the human genome assembly GRCh38 using HISAT2. Resultant BAM files were annotated to chromosomal coordinates with featureCounts and further analyzed with DESeq2. Data analyses were compared between subjects with VL and controls using hierarchical clustering and heatmaps, and principal components analyses. The results revealed two outlier subjects, and potential mild clustering between subjects with VL and controls with malignancy. An alternate approach employed RankProd, which uses an algorithm based on rank order rather than absolute counts. Transcriptome unmapped are also aligned with microbial genomes to show the metagenomes associated with symptomatic VL. The outcomes of these approaches highlighted inflammatory genes that were up- rather than down-regulated in blood monocytes of subjects with VL. During VL there may be an immune suppressive effect on CD4+ helper T-cells, but a pro-inflammatory effect on CD14+ phagocytic cells.
Advisor: Andrew Kitchen (IGPI | Anthropology)