title: Revealing parasite influence in metabolic pathways in Apicomplexa infected patients.
abstract: BACKGROUND
  As an obligate intracellular parasite, Apicomplexa interacts with the host in the special living environment, competing for energy and nutrients from the host cells by manipulating the host metabolism. Previous studies of host-parasite interaction mainly focused on using cellular and biochemical methods to investigate molecular functions in metabolic pathways of parasite infected hosts. Computational approaches taking advantage of high-throughput biological data and topology of metabolic pathways have a great potential in revealing the details and mechanism of parasites-to-host interactions. A new analytical method was designed in this work to study host-parasite interactions in human cells infected with Plasmodium falciparum and Cryptosporidium parvum.
  
  
  RESULTS
  We introduced a new method that analyzes the host metabolic pathways in divided parts: host specific subpathways and host-parasite common subpathways. Upon analysis on gene expression data from cells infected by Plasmodium falciparum or Cryptosporidium parvum, we found: (i) six host-parasite common subpathways and four host specific subpathways were significantly altered in plasmodium infected human cells; (ii) plasmodium utilized fatty acid biosynthesis and elongation, and Pantothenate and CoA biosynthesis to obtain nutrients from host environment; (iii) in Cryptosporidium parvum infected cells, most of the host-parasite common enzymes were down-regulated, whereas the host specific enzymes up-regulated; (iv) the down-regulation of common subpathways in host cells might be caused by competition for the substrates and up-regulation of host specific subpathways may be stimulated by parasite infection.
  
  
  CONCLUSIONS
  Results demonstrated a significantly coordinated expression pattern between the two groups of subpathways. The method helped expose the impact of parasite infection on host cell metabolism, which was previously concealed in the pathway enrichment analysis. Our approach revealed detailed subpathways and metabolic information are important to the symbiosis in two kinds of the apicomplex parasites, and highlighted its significance in research and understanding of parasite-host interactions.
authors.affiliation: College of life science and biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China. xutaoseu@hotmail.com
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Jie
authors.initials: J
authors.lastname: Ping
authors.forename: Yao
authors.initials: Y
authors.lastname: Yu
authors.forename: Fudong
authors.initials: F
authors.lastname: Yu
authors.forename: Yongtao
authors.initials: Y
authors.lastname: Yu
authors.forename: Pei
authors.initials: P
authors.lastname: Hao
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
mesh_terms: D000818:Animals; D002460:Cell Line; D016785:Cryptosporidium parvum / Q000502:physiology*; D015536:Down-Regulation; D015870:Gene Expression; D006790:Host-Parasite Interactions; D006801:Humans; D016778:Malaria, Falciparum / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D053858:Metabolic Networks and Pathways; D010963:Plasmodium falciparum / Q000502:physiology*; D015854:Up-Regulation