Virus host interactions in clinical samples

Division Of Basic Sciences - Nci

Investigators

Linked publications & trials

Abstract

In collaboration with Drs. Yarchoan, Ramaswami, Lurain, and Krug in HAMB, we have been investigating human and viral gene expression patterns in normal tissue, in Kaposi sarcoma (KS), and other KSHV-infected pathological tissues. Little is known about cellular and viral RNA transcripts in KS lesions and how these factors are influenced by prior therapy, concurrent KSHV-associated diseases, or the tissue location of KS lesions. We sought to understand how human gene expression and viral transcripts are altered in KS as compared to normal tissue using matched patient samples. In this study of participants with well-annotated clinical characteristics, we also investigated both skin and GI KS to determine differences in the viral and host transcripts between these lesions. In our study, we analyzed samples from 19 participants, including both cutaneous and gastrointestinal (GI) Kaposi's sarcoma (KS) samples. The majority of these individuals were coinfected with HIV, and some presented other conditions such as KICS, MCD, and PEL. Upon analysis, we found that GI KS samples had a higher viral load (VL) for KSHV than the skin KS samples, and similarly, HIV VL was also higher in individuals with GI KS. The CD4+ T cell counts were however, comparable in both types of KS samples. In investigating gene expression patterns, we discovered significant differences in differentially expressed genes (DEGs) between the two types of KS lesions. We identified 370 DEGs unique to skin KS, 58 DEGs unique to GI KS, and 26 common to both compared to their normal tissues. Notably, we found enrichment in IL-6 signaling, HIFalpha signaling, and the granulocyte adhesion and diapedesis pathway in both locations of KS. The B cell receptor signaling pathway, however, was only enriched in the skin KS samples. There were also some genes that showed distinct patterns in GI and skin KS, such as IL1A, which was upregulated in GI KS but repressed in skin KS. When we investigated genes associated with inflammatory response and cytokine dysregulation, we found differences based on KS location. For instance, IL6 and IL10 RNA levels were increased in skin KS, but not significantly altered in GI KS. Furthermore, VEGF receptors, critical in angiogenesis, were upregulated in skin KS, while the receptor VEGFR3 was increased in both skin and GI KS. We also observed a wide range of expression changes in IFN-gamma, which is known to combat KSHV infection. When exploring Kaposi's sarcoma-associated herpesvirus (KSHV) gene expression in both GI and skin KS lesions, we found heterogeneity in KSHV expression patterns. Three distinct patterns were observed across multiple lesions. ORF75 was significantly present in 91% of all KS lesions, an intriguing finding given that it's typically only expressed in lytically-infected cells. There were also unexpected trends in KSHV gene expression that warrant further investigation. Lastly, we decided to further explore the expression of STC1 and FLT4, both upregulated in GI and skin lesions. By using the lymphatic endothelial cells (LECs) model, we confirmed an increase in STC1 and FLT4 expression with KSHV infection or reactivation. We used small interfering RNAs (siRNAs) to investigate the impact of STC1 and FLT4 expression on viral infection and angiogenesis. Suppressing STC1 led to decreased viral gene expression and virion production. Additionally, targeting STC1 or FLT4 decreased the number of angiogenesis markers in a cell culture assay, suggesting that increased expression of these genes may contribute to enhanced angiogenesis within KS lesions. Overall, our study revealed significant differences in gene expression in skin and GI KS lesions, providing valuable insights into the pathogenesis of Kaposi Sarcoma. The differential gene expression in these lesions may help guide future research and treatment approaches. Further investigations into the roles of STC1 and FLT4 in KSHV infection and angiogenesis are warranted, which could lead to novel therapeutic strategies.