Anti-Interleukin-10 unleashes transcriptional response to leishmanial antigen in whole blood of visceral leishmaniasis patients

Visceral leishmaniasis (VL; Leishmania donovani) cases produce interferon- (IFN) and tumour necrosis factor (TNF) in response to soluble leishmanial antigen (SLA) in whole blood assays. These pro-inflammatory cytokines are crucial for activation of macrophages to kill L. donovani parasites. Detailed immunological studies comparing active with cured patients suggest that a balance exists between the pro-inflammatory cytokines TNF and IFN, and anti-inflammatory interleukin-10 (IL10). Our interest was to obtain a global understanding of the response to SLA in whole blood from active VL cases, and to determine what effect neutralising anti-IL10 would have on this response. Transcriptional profiles following SLA stimulation of whole blood from VL patients showed very few differentially expressed genes (DEGs), the majority belonging to a single network with TNF at the hub. In contrast, when anti-IL10 was added with SLA, hundreds of DEGs were observed, 65% belonging to a single network with TNF, IFNG, NFKBIA, IL6 and IL1B as hub genes in concert with a remarkable chemokine/cytokine storm. Our data demonstrate the singular impact of IL10 as a potent immune modulator in VL. Whole blood from active cases (pre-treatment; day 0) was stimulated with SLA with/without isotype control antibody or anti-IL10. Whole blood collected at day 30 post-treatment was unstimulated or stimulated with SLA alone. Samples from different experimental groups were distributed evenly across 4 Illumina HT12v4 expression beadchips.