Targeting essential Eimeria ninakohlyakimovae sporozoite ligands for caprine host endothelial cell invasion with a phage display peptide library

Matrine disturbs the eimeria necatrix-induced loop of tuft cell-intestinal stem cell-goblet cell by inactivating IL-13/JAK2/STAT3 signaling

As sensors in the gut, tuft cells integrate a complex array of luminal signals to regulate the differentiation fate of intestinal stem cells (ISCs), which trigger a loop of tuft cell-ISC-goblet cell after parasitic infection. As a plant-derived alkaloid, Matrine plays a prominent role for standardizing ISC functions in Eimeria necatrix (EN)-exposed chicks. In this study, we investigated the modulation effects of Matrine on the specific intestinal epithelial cell loop in EN-exposed chicks in vivo and intestinal organoids (IOs) ex vivo. The results showed that EN infection resulted in swelling and hemorrhage of the jejunum, accompanied by the increase in levels of sIgA and inflammatory cytokines (IL-6, IL-1β, and TNF-α). And these inflammatory symptoms were effectively relieved by Matrine intervention. Concurrently, Matrine resisted the EN-induced increase in tuft cell numbers and levels of crucial pro-inflammatory factors (IL-25 and IL-13), while also reversing the differentiation of secretory cell progenitors into goblet cells. Importantly, Matrine impeded the upregulation of the inflammatory signaling pathway JAK2/STAT3 in EN-infected chicks and IOs. Conversely, exogenous supplementation of IL-13 or activation of STAT3 via Colivelin eliminated the standardization of the tuft cell-ISC-goblet cell loop by Matrine. Overall, our findings suggested that Matrine intercepted the tuft cell-ISC-goblet cell loop by reinstating IL-13/JAK2/STAT3 signaling after EN infection.

Unbiased phage display screening identifies hidden malaria vaccine targets

Malaria is among the deadliest infectious diseases. Over 200 million annual clinical malaria cases are reported and more than half a million people, mostly children, die every year. The most advanced RTS,S/AS01 vaccine based on the P. falciparum circumsporozoite protein (CSP), targets sporozoite liver infection but achieved modest efficacy. To reduce malaria death, novel malaria vaccine development is a high priority. Most malaria vaccine candidates target three infection steps: sporozoite liver infection, merozoite red blood cell (RBC) infection, and mosquito midgut infection. However, only few malaria vaccine candidates target specific parasite-host cell interactions. Our group has implemented the phage peptide-display approach to discover new parasite ligands and host cell receptors. Here we summarize our findings and discuss their potential for the development of novel vaccines.

Computational and Experimental Approaches to Predict Host-Parasite Protein-Protein Interactions

In host-parasite systems, protein-protein interactions are key to allow the pathogen to enter the host and persist within the host. The study of host-parasite molecular communication improves the understanding the mechanisms of infection, evasion of the host immune system and tropism across different tissues. Current trends in parasitology focus on unraveling host-parasite protein-protein interactions to aid the development of new strategies to combat pathogenic parasites with better treatments and prevention mechanisms. Due to the complexity of capturing experimentally these interactions, computational approaches integrating data from different sources (mainly "omics" data) become key to complement or support experimental approaches. Here, we focus on the application of experimental and computational methods in the prediction of host-parasite interactions and highlight the potential of each of these methods in specific contexts.

Molecular analyses on Neospora caninum-triggered NETosis in the caprine system

Neospora caninum is an obligate intracellular protozoan parasite causing serious reproductive disorders in large and small ruminants worldwide. Polymorphonuclear neutrophils (PMN) react against multiple invading pathogens through different mechanisms including the release of neutrophil extracellular traps (NETs). Here, in vitro interactions of caprine PMN and N. caninum tachyzoites were studied. Scanning electron microscopic- and immunofluorescence-analyses demonstrated that caprine PMN undergo NETosis upon contact with tachyzoites of N. caninum, extruding filaments that entrap parasites. Detailed co-localization studies of N. caninum tachyzoite-induced NETs revealed the presence of PMN-derived DNA being decorated with histones (H1, H2A/H2B, H3,H4) and neutrophil elastase (NE) corroborating the molecular characteristics of classical mammalian NETs. As a new result for parasite-induced NETosis, we identified pentraxin and cathepsin B in N. caninum-triggered NETs. Nonetheless, functional inhibition assays revealed that during caprine NET formation triggered by N. caninum different molecular signaling pathways are induced, when compared to other apicomplexan parasites or host species. As such, N. caninum-induced NETosis appears to be influenced by MPO but independent of NADPH oxidase, SOCE, ERK1/2 and p38 MAPK activities. Furthermore, the inhibition of PMN autophagy via blockage of the PI3K-mediated signaling pathway failed to influence tachyzoite-induced NETosis. Since N. caninum-tachyzoites induced caprine NETosis, this effector mechanism should be considered as an early host immune response during acute caprine neosporosis.