Attenuated Leishmania induce pro-inflammatory mediators and influence leishmanicidal activity by p38 MAPK dependent phagosome maturation in Leishmania donovani co-infected macrophages

Promastigote form of Leishmania, an intracellular pathogen, delays phagosome maturation and resides inside macrophages. But till date limited study has been done to manipulate the phagosomal machinery of macrophages to restrict Leishmania growth. Attenuated Leishmania strain exposed RAW 264.7 cells showed a respiratory burst and enhanced production of pro-inflammatory mediators. The augmentation of pro-inflammatory activity is mostly attributed to p38 MAPK and p44/42 MAPK. In our study, these activated macrophages are found to induce phagosome maturation when infected with pathogenic Leishmania donovani. Increased co-localization of carboxyfluorescein succinimidyl ester labeled pathogenic L. donovani with Lysosome was found. Moreover, increased co-localization was observed between pathogenic L. donovani and late phagosomal markers viz. Rab7, Lysosomal Associated Membrane Protein 1, Cathepsin D, Rab9, and V-ATPase which indicate phagosome maturation. It was also observed that inhibition of V-type ATPase caused significant hindrance in attenuated Leishmania induced phagosome maturation. Finally, it was confirmed that p38 MAPK is the key player in acidification and maturation of phagosome in attenuated Leishmania strain preexposed macrophages. To our knowledge, this study for the first time reported an approach to induce phagosome maturation in L. donovani infected macrophages which could potentiate short-term prophylactic response in futur

Macrophage as the Game Changer of the (Future) Therapeutic Paradigm

Macrophages, the executioner of phagosome maturation, are central to coordinate and cooperate as the bridge between innate and acquired immunity. Mice primed with attenuated Leishmania promastigote showed host defense, such as total protection against LPS-induced endotoxic shock and, diarrhoeagenic E. coli lethal infection. Cell-based empirical preparations and isolated lipids, sphingolipids and lipoproteins were made out of the promastigotes. Host macrophage-mediated enhancement of microbicidal actions, non-specific and specific host immunity boosting and mitigation of antomicrobial resistance by the empirical preparations and, the cancer cell apoptosis, resolution of sepsis, combating autoimmune disease by isolated chemical constituents were evident, respectively. Macrophage phagosome maturation is the key factor of all these changes and indeed the attenuated Leishmania promastigote was found as an efficient agent for such maturation. To assess clinical impact of the studies, the therapeutic aspects of isolated total promastigote lipid were investigated on the synovial fluid mononuclear cells of RA (rheumatoid arthritis) patient as a case study including an animal model of the disease in parallel. The use of the attenuated Leishmania promastigote to produce human therapeutic vaccines that served Indian people for decades (1954–2005) by a nearly unknown Kolkata (India) based firm (IBL) was rediscovered recently

Leishmania mexicana induced perturbations of macrophage metabolism

The interaction between the Leishmania parasite and the macrophage is a bidirectional one of which the outcome of is important for determining if disease progresses or regresses. The parasite is able to modulate the host cell at epigenetic, transcript and metabolic levels. In the context of the latter, immune metabolism is a rapidly growing area of research, and its importance in the context of normal immune function and pathology is increasingly being recognised. In this thesis a robust, untargeted metabolomics protocol has been developed in order to profile a classical in vitro model of immune metabolism, the inflammatory M1 macrophage. While previous studies use single or multiple M1 stimuli without dissecting their importance, a combinatorial approach is used here to dissect the contribution and interaction of two key M1 stimuli, interferon γ (IFNγ) and LPS. An obvious stimulus-specific response is obvious in our data. We next used this untargeted metabolomics protocol in parallel with RNAseq to examine the cost of hosting a parasite to the macrophages metabolic and transcriptional profile. By using a heat-killed control it was possible to differentiate between general immune responses and response specific to the live parasite. Additionally, a FACS protocol coupled to untargeted metabolomics was used in order to focus on the infected cell. Furthermore, the inclusion of the above mentioned M1 control revealed that either live or heat-killed Leishmania failed to elicit as strong a response. Finally, stable isotope labelled metabolomics was used to validate key findings. In summary, our untargeted metabolomics protocol has revealed immune- metabolic perturbations that are induced by IFNγ and LPS or their interaction. This information should be considered if targeting these pathways in a therapeutic context. Furthermore, by using an integrated metabolic- transcriptomics profiling approach, perturbations in glycerol-phospholipid metabolism, central carbon metabolism and arginine metabolism were found. Using stable isotope labelled metabolomics (U13C-Arginine) the current study has given unprecedented insight into how the parasite utilises this crucial amino acid, as well as confirm novel pathways