Deciphering genetic regulation of CD14 by SP1 through characterization of peripheral blood mononuclear transcriptome of P. faiciparum and P. vivax infected malaria patients

BACKGROUND: Plasmodium falciparum and Plasmodium vivax are two major parasites responsible for malaria which remains a threat to almost 50% of world's population despite decade-long eradication program. One possible reason behind this conundrum is that the bases of clinical variability in malaria caused by either species are complex and poorly understood. METHODS: Whole-genome transcriptome was analyzed to identify the active and predominant pathways in the PBMC of P. falciparum and P. vivax infected malaria patients. Deregulated genes were identified and annotated using R Bioconductor and DAVID/KEGG respectively. Genetic and functional regulation of CD14, a prioritized candidate, were established by quantitative RT-PCR, genotyping using RFLP and resequencing, mapping of transcription factor binding using CONSITE and TFBIND, dual luciferase assay, western blot analysis, RNAi- mediated gene knockdown and chromatin-immunoprecipation. FINDINGS: The study highlighted that deregulation of host immune and inflammatory genes particularly CD14 as a key event in P. falciparum malaria. An abundance of allele-C of rs5744454, located in CD14 promoter, in severe malaria motivated us to establish an allele-specific regulation of CD14 by SP1. An enhancement of SP1 and CD14 expression was observed in artemisinin treated human monocyte cell line. INTERPRETATION: Our data not only reinstates that CD14 of TLR pathway plays a predominant role in P. falciparum malaria, it establishes a functional basis for genetic association of rs5744454 with P. falciparum severe malaria by demonstrating a cis-regulatory role of this promoter polymorphism. Moreover, the study points towards a novel pharmacogenetic aspect of artemisinin-based anti-malarial therapy. FUND: DST-SERB, Govt. of India, SR/SO/HS-0056/2013.