Immuno-metabolic profile of human macrophages after Leishmania and Trypanosoma cruzi infection

Early Leishmania infectivity depends on miR-372/373/520d family-mediated reprogramming of polyamines metabolism in THP-1-derived macrophages

Leishmania amazonensis is a protozoan that primarily causes cutaneous leishmaniasis in humans. The parasite relies on the amino acid arginine to survive within macrophages and establish infection, since it is a precursor for producing polyamines. On the other hand, arginine can be metabolized via nitric oxide synthase 2 (NOS2) to produce the microbicidal molecule nitric oxide (NO), although this mechanism does not apply to human macrophages since they lack NOS2 activity. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at posttranscriptional levels. Our previous work showed that mmu-miR-294 targets Nos2 favoring Leishmania survival in murine macrophages. Here, we demonstrate that human macrophages upregulate the hsa-miR-372, hsa-miR-373, and hsa-miR-520d, which present the same seed sequence as the murine mmu-miR-294. Inhibition of the miR-372 impaired Leishmania survival in THP-1 macrophages and the effect was further enhanced with combinatorial inhibition of the miR-372/373/520d family, pointing to a cooperative mechanism. However, this reduction in survival is not caused by miRNA-targeting of NOS2, since the seed-binding motif found in mice is not conserved in the human 3'UTR. Instead, we showed the miR-372/373/520d family targeting the macrophage's main arginine transporter SLC7A2/CAT2 during infection. Arginine-related metabolism was markedly altered in response to infection and miRNA inhibition, as measured by Mass Spectrometry-based metabolomics. We found that Leishmania infection upregulates polyamines production in macrophages, as opposed to simultaneous inhibition of miR-372/373/520d, which decreased putrescine and spermine levels compared to the negative control. Overall, our study demonstrates miRNA-dependent modulation of polyamines production, establishing permissive conditions for intracellular parasite survival. Although the effector mechanisms causing host cell immunometabolic adaptations involve various parasite and host-derived signals, our findings suggest that the miR-372/373/520d family may represent a potential target for the development of new therapeutic strategies against cutaneous leishmaniasis.

Leishmania major centrin knock-out parasites reprogram tryptophan metabolism to induce a pro-inflammatory response

Leishmaniasis is a parasitic disease that is prevalent in 90 countries, and yet no licensed human vaccine exists against it. Toward control of leishmaniasis, we have developed Leishmania major centrin gene deletion mutant strains (LmCen-/-) as a live attenuated vaccine, which induces a strong IFN-γ-mediated protection to the host. However, the immune mechanisms of such protection remain to be understood. Metabolomic reprogramming of the host cells following Leishmania infection has been shown to play a critical role in pathogenicity and shaping the immune response following infection. Here, we applied untargeted mass spectrometric analysis to study the metabolic changes induced by infection with LmCen-/- and compared those with virulent L. major parasite infection to identify the immune mechanism of protection. Our data show that immunization with LmCen-/- parasites, in contrast to virulent L. major infection promotes a pro-inflammatory response by utilizing tryptophan to produce melatonin and downregulate anti-inflammatory kynurenine-AhR and FICZ-AhR signaling.

Immuno-metabolic signaling in leishmaniasis: insights gained from mathematical modeling

Motivation

Leishmaniasis is a global concern especially in underdeveloped and developing subtropical and tropical regions. The extent of infectivity in host is majorly dependent on functional polarization of macrophages. Classically activated M1 macrophage can eliminate parasite through production of iNOS and alternatively activated M2 macrophages can promote parasite growth through by providing shelter and nutrients to parasite. The biological processes involved in immune signaling and metabolism of host and parasite might be responsible for deciding fate of parasite.

Results

Using systems biology approach, we constructed two mathematical models and inter-regulatory immune-metabolic networks of M1 and M2 state, through which we identified crucial components that are associated with these phenotypes. We also demonstrated how parasite may modulate M1 phenotype for its growth and proliferation and transition to M2 state. Through our previous findings as well as from recent findings we could identify SHP-1 as a key component in regulating the immune-metabolic characterization of M2 macrophage. By targeting SHP-1 at cellular level, it might be possible to modulate immuno-metabolic mechanism and thereby control parasite survival.

Availability and implementation

Mathematical modeling is implemented as a workflow and the models are deposited in BioModel database. FactoMineR is available at: https://github.com/cran/FactoMineR/tree/master.

Leishmania donovani Induces Multiple Dynamic Responses in the Metabolome Associated with Amastigote Differentiation and Maturation Inside the Human Macrophage

Leishmania donovani infection of macrophages drives profound changes in the metabolism of both the host macrophage and the parasite, which undergoes different phases of development culminating in replication and propagation. However, the dynamics of this parasite-macrophage cometabolome are poorly understood. In this study, a multiplatform metabolomics pipeline combining untargeted, high-resolution CE-TOF/MS and LC-QTOF/MS with targeted LC-QqQ/MS was followed to characterize the metabolome alterations induced in L. donovani-infected human monocyte-derived macrophages from different donors at 12, 36, and 72 h post-infection. The set of alterations known to occur during Leishmania infection of macrophages, substantially expanded in this investigation, characterized the dynamics of the glycerophospholipid, sphingolipid, purine, pentose phosphate, glycolytic, TCA, and amino acid metabolism. Our results showed that only citrulline, arginine, and glutamine exhibited constant trends across all studied infection time points, while most metabolite alterations underwent a partial recovery during amastigote maturation. We determined a major metabolite response pointing to an early induction of sphingomyelinase and phospholipase activities and correlated with amino acid depletion. These data represent a comprehensive overview of the metabolome alterations occurring during promastigote-to-amastigote differentiation and maturation of L. donovani inside macrophages that contributes to our understanding of the relationship between L. donovani pathogenesis and metabolic dysregulation.

Leishmaniasis: Immune Cells Crosstalk in Macrophage Polarization

Leishmaniasis is a complex infectious parasitic disease caused by protozoa of the genus Leishmania, belonging to a group of neglected tropical diseases. It establishes significant global health challenges, particularly in socio-economically disadvantaged regions. Macrophages, as innate immune cells, play a crucial role in initiating the inflammatory response against the pathogens responsible for this disease. Macrophage polarization, the process of differentiating macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, is essential for the immune response in leishmaniasis. The M1 phenotype is associated with resistance to Leishmania infection, while the M2 phenotype is predominant in susceptible environments. Notably, various immune cells, including T cells, play a significant role in modulating macrophage polarization by releasing cytokines that influence macrophage maturation and function. Furthermore, other immune cells can also impact macrophage polarization in a T-cell-independent manner. Therefore, this review comprehensively examines macrophage polarization's role in leishmaniasis and other immune cells' potential involvement in this intricate process.

Statins change the cytokine profile in Trypanosoma cruzi-infected U937 macrophages and murine cardiac tissue through Rho-associated kinases inhibition

Introduction

Chronic Chagasic cardiomyopathy (CCC), caused by the protozoan Trypanosoma cruzi, is the most severe manifestation of Chagas disease.CCC is characterized by cardiac inflammation and fibrosis caused by a persistent inflammatory response. Following infection, macrophages secrete inflammatory mediators such as IL-1β, IL-6, and TNF-α to control parasitemia. Although this response contains parasite infection, it causes damage to the heart tissue. Thus, the use of immunomodulators is a rational alternative to CCC. Rho-associated kinase (ROCK) 1 and 2 are RhoA-activated serine/threonine kinases that regulate the actomyosin cytoskeleton. Both ROCKs have been implicated in the polarization of macrophages towards an M1 (pro-inflammatory) phenotype. Statins are FDA-approved lipid-lowering drugs that reduce RhoA signaling by inhibiting geranylgeranyl pyrophosphate (GGPP) synthesis. This work aims to identify the effect of statins on U937 macrophage polarization and cardiac tissue inflammation and its relationship with ROCK activity during T. cruzi infection.

Methods

PMA-induced, wild-type, GFP-, CA-ROCK1- and CA-ROCK2-expressing U937 macrophages were incubated with atorvastatin, or the inhibitors Y-27632, JSH-23, TAK-242, or C3 exoenzyme incubated with or without T. cruzi trypomastigotes for 30 min to evaluate the activity of ROCK and the M1 and M2 cytokine expression and secretion profiling. Also, ROCK activity was determined in T. cruzi-infected, BALB/c mice hearts.

Results

In this study, we demonstrate for the first time in macrophages that incubation with T. cruzi leads to ROCK activation via the TLR4 pathway, which triggers NF-κB activation. Inhibition of ROCKs by Y-27632 prevents NF-κB activation and the expression and secretion of M1 markers, as does treatment with atorvastatin. Furthermore, we show that the effect of atorvastatin on the NF-kB pathway and cytokine secretion is mediated by ROCK. Finally, statin treatment decreased ROCK activation and expression, and the pro-inflammatory cytokine production, promoting anti-inflammatory cytokine expression in chronic chagasic mice hearts.

Conclusion

These results suggest that the statin modulation of the inflammatory response due to ROCK inhibition is a potential pharmacological strategy to prevent cardiac inflammation in CCC.

Macrophage Mitochondrial Biogenesis and Metabolic Reprogramming Induced by Leishmania donovani Require Lipophosphoglycan and Type I Interferon Signaling

Pathogen-specific rewiring of host cell metabolism creates the metabolically adapted microenvironment required for pathogen replication. Here, we investigated the mechanisms governing the modulation of macrophage mitochondrial properties by the vacuolar pathogen Leishmania. We report that induction of oxidative phosphorylation and mitochondrial biogenesis by Leishmania donovani requires the virulence glycolipid lipophosphoglycan, which stimulates the expression of key transcriptional regulators and structural genes associated with the electron transport chain. Leishmania-induced mitochondriogenesis also requires a lipophosphoglycan-independent pathway involving type I interferon (IFN) receptor signaling. The observation that pharmacological induction of mitochondrial biogenesis enables an avirulent lipophosphoglycan-defective L. donovani mutant to survive in macrophages supports the notion that mitochondrial biogenesis contributes to the creation of a metabolically adapted environment propitious to the colonization of host cells by the parasite. This study provides novel insight into the complex mechanism by which Leishmania metacyclic promastigotes alter host cell mitochondrial biogenesis and metabolism during the colonization process. IMPORTANCE To colonize host phagocytes, Leishmania metacyclic promastigotes subvert host defense mechanisms and create a specialized intracellular niche adapted to their replication. This is accomplished through the action of virulence factors, including the surface coat glycoconjugate lipophosphoglycan. In addition, Leishmania induces proliferation of host cell mitochondria as well as metabolic reprogramming of macrophages. These metabolic alterations are crucial to the colonization process of macrophages, as they may provide metabolites required for parasite growth. In this study, we describe a new key role for lipophosphoglycan in the stimulation of oxidative phosphorylation and mitochondrial biogenesis. We also demonstrate that host cell pattern recognition receptors Toll-like receptor 4 (TLR4) and endosomal TLRs mediate these Leishmania-induced alterations of host cell mitochondrial biology, which also require type I IFN signaling. These findings provide new insight into how Leishmania creates a metabolically adapted environment favorable to their replication.

Echinococcus multilocularis protoscoleces enhance glycolysis to promote M2 Macrophages through PI3K/Akt/mTOR Signaling Pathway

Alveolar Echinococcosis (AE) is a zoonotic parasitic disease caused by Echinococcus multilocularis, but its pathogenesis remains unclear. The primary objective of this study is to explore whether Echinococcus multilocularis protoscoleces (PSCs) regulate macrophage polarization and glucose metabolism by PI3K/Akt/mTOR signaling pathway. We found that large numbers of CD68⁺ macrophages gathered in close liver issue from the lesion in AE patients. PSCs preferentially differentiated into M2 macrophages and the expressions of HK1, PFKL, PKM2, PI3K, Akt, p-Akt, mTOR and p-mTOR increased. The above results show that Echinococcus multilocularis protoscoleces enhance glycolysis to promote M2 macrophages through PI3K/Akt/mTOR signaling pathway.

Modulation of Macrophage Immunometabolism: A New Approach to Fight Infections

Macrophages are essential innate immune cells that contribute to host defense during infection. An important feature of macrophages is their ability to respond to extracellular cues and to adopt different phenotypes and functions in response to these stimuli. The evidence accumulated in the last decade has highlighted the crucial role of metabolic reprogramming during macrophage activation in infectious context. Thus, understanding and manipulation of macrophage immunometabolism during infection could be of interest to develop therapeutic strategies. In this review, we focus on 5 major metabolic pathways including glycolysis, pentose phosphate pathway, fatty acid oxidation and synthesis, tricarboxylic acid cycle and amino acid metabolism and discuss how they sustain and regulate macrophage immune function in response to parasitic, bacterial and viral infections as well as trained immunity. At the end, we assess whether some drugs including those used in clinic and in development can target macrophage immunometabolism for potential therapy during infection with an emphasis on SARS-CoV2 infection.

Glyceraldehyde-3-phosphate dehydrogenase present in extracellular vesicles from Leishmania major suppresses host TNF-alpha expression

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) fulfills various physiological roles that are unrelated to its glycolytic function. However, to date, the nonglycolytic function of GAPDH in trypanosomal parasites is absent from the literature. Exosomes secreted from Leishmania, like entire parasites, were found to have a significant impact on macrophage cell signaling and function, indicating cross talk with the host immune system. In this study, we demonstrate that the Leishmania GAPDH (LmGAPDH) protein is highly enriched within the extracellular vesicles (EVs) secreted during infection. To understand the function of LmGAPDH in EVs, we generated control, overexpressed, half-knockout (HKO), and complement cell lines. HKO cells displayed lower virulence compared with control cells when macrophages and BALB/c mice were infected with them, implying a crucial role for LmGAPDH in Leishmania infection and disease progression. Furthermore, upon infection of macrophages with HKO mutant Leishmania and its EVs, despite no differences in TNFA mRNA expression, there was a considerable increase in TNF-α protein expression compared with control, overexpressed, and complement parasites as determined by ELISA, RT-PCR, and immunoblot data. In vitro protein translation studies suggest that LmGAPDH-mediated TNF-α suppression occurs in a concentration-dependent manner. Moreover, mRNA binding assays also verified that LmGAPDH binds to the AU-rich 3′-UTR region of TNFA mRNA, limiting its production. Together, these findings confirmed that the LmGAPDH contained in EVs inhibits TNF-α expression in macrophages during infection via posttranscriptional repression.

Pyruvate Dehydrogenase Kinase Inhibitor Dichloroacetate Improves Host Control of Salmonella enterica Serovar Typhimurium Infection in Human Macrophages

Global increases in the prevalence of antimicrobial resistance highlight the urgent need for novel strategies to combat infectious diseases. Recent studies suggest that host metabolic pathways play a key role in host control of intracellular bacterial pathogens. In this study we explored the potential of targeting host metabolic pathways for innovative host-directed therapy (HDT) against intracellular bacterial infections. Through gene expression profiling in human macrophages, pyruvate metabolism was identified as potential key pathway involved in Salmonella enterica serovar Typhimurium (Stm) infections. Next, the effect of targeting pyruvate dehydrogenase kinases (PDKs) - which are regulators of the metabolic checkpoint pyruvate dehydrogenase complex (PDC) - on macrophage function and bacterial control was studied. Chemical inhibition of PDKs by dichloroacetate (DCA) induced PDC activation and was accompanied with metabolic rewiring in classically activated macrophages (M1) but not in alternatively activated macrophages (M2), suggesting cell-type specific effects of dichloroacetate on host metabolism. Furthermore, DCA treatment had minor impact on cytokine and chemokine secretion on top of infection, but induced significant ROS production by M1 and M2. DCA markedly and rapidly reduced intracellular survival of Stm, but interestingly not Mycobacterium tuberculosis, in human macrophages in a host-directed manner. In conclusion, DCA represents a promising novel HDT compound targeting pyruvate metabolism for the treatment of Stm infections.

Immune-metabolic interactions between Leishmania and macrophage host

Manipulation of host metabolic fluxes by Leishmania represents a strategy to circumvent host immune response leading to long-term parasite survival and playing an important role in the pathology of infection. Specific Leishmania-dependent metabolic alterations in infected macrophages have been associated with resistance or susceptibility to infection. Thus, deciphering the multilevel interactions between metabolism and function on innate immune cells during infection offers considerable therapeutic or prophylactic promise. In this review, we provide an overview of recent literature highlighting Leishmania-macrophage interactions and discuss the potential of metabolic targeted therapies to shift the balance of dysfunctional, damaging, or non-productive responses to protective immune reactivity patterns towards pathogen elimination.

Dynamicity in Host Metabolic Adaptation Is Influenced by the Synergistic Effect of Eugenol Oleate and Amphotericin B During Leishmania donovani Infection In Vitro

Immune metabolic adaptation in macrophages by intracellular parasites is recognized to play a crucial role during Leishmania infection. However, there is little accessible information about changes in a metabolic switch in L. donovani infected macrophages. In previous studies, we have reported on the anti-leishmanial synergic effect of eugenol oleate with amphotericin B. In the present study, we demonstrated that glycolytic enzymes were highly expressed in infected macrophages during combinatorial treatment of eugenol oleate (2.5 µM) and amphotericin B (0.3125 µM). Additionally, we found that the biphasic role in arachidonic acid metabolite, PGE2, and LTB4, is released during this treatment. In vitro data showed that COX-2 mediated PGE2 synthesis increased significantly (p<0.01) in infected macrophages. Not only was the level of prostaglandin synthesis decreased 4.38 fold in infected macrophages after treatment with eugenol oleate with amphotericin B. The mRNA expression of PTGES, MPGES, and PTGER4 were also moderately expressed in infected macrophages, and found to be decreased in combinatorial treatment. In addition, NOS2 expression was activated by the phosphorylation of p38MAPK when combination-treated macrophages were promoted to kill intracellular parasites. The findings of the present study indicate that the synergism between eugenol oleate and amphotericin B could play an important role in immune metabolism adaptation with a concomitant increase in host immune response against the intracellular pathogen, L. donovani.

Dysregulation of Glycerophosphocholines in the Cutaneous Lesion Caused by Leishmania major in Experimental Murine Models

Cutaneous leishmaniasis (CL) is the most common disease form caused by a Leishmania parasite infection and considered a neglected tropical disease (NTD), affecting 700,000 to 1.2 million new cases per year in the world. Leishmania major is one of several different species of the Leishmania genus that can cause CL. Current CL treatments are limited by adverse effects and rising resistance. Studying disease metabolism at the site of infection can provide knowledge of new targets for host-targeted drug development. In this study, tissue samples were collected from mice infected in the ear or footpad with L. major and analyzed by untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS). Significant differences in overall metabolite profiles were noted in the ear at the site of the lesion. Interestingly, lesion-adjacent, macroscopically healthy sites also showed alterations in specific metabolites, including selected glycerophosphocholines (PCs). Host-derived PCs in the lower m/z range (m/z 200-799) showed an increase with infection in the ear at the lesion site, while those in the higher m/z range (m/z 800-899) were decreased with infection at the lesion site. Overall, our results expanded our understanding of the mechanisms of CL pathogenesis through host metabolism and may lead to new curative measures against infection with Leishmania.

Tryp-ing Up Metabolism: Role of Metabolic Adaptations in Kinetoplastid Disease Pathogenesis

Today, more than a billion people-one-sixth of the world's population-are suffering from neglected tropical diseases. Human African trypanosomiasis, Chagas disease, and leishmaniasis are neglected tropical diseases caused by protozoan parasites belonging to the genera Trypanosoma and Leishmania About half a million people living in tropical and subtropical regions of the world are at risk of contracting one of these three infections. Kinetoplastids have complex life cycles with different morphologies and unique physiological requirements at each life cycle stage. This review covers the latest findings on metabolic pathways impacting disease pathogenesis of kinetoplastids within the mammalian host. Nutrient availability is a key factor shaping in vivo parasite metabolism; thus, kinetoplastids display significant metabolic flexibility. Proteomic and transcriptomic profiles show that intracellular trypanosomatids are able to switch to an energy-efficient metabolism within the mammalian host system. Host metabolic changes can also favor parasite persistence, and contribute to symptom development, in a location-specific fashion. Ultimately, targeted and untargeted metabolomics studies have been a valuable approach to elucidate the specific biochemical pathways affected by infection within the host, leading to translational drug development and diagnostic insights.

The antioxidant response favors Leishmania parasites survival, limits inflammation and reprograms the host cell metabolism

The oxidative burst generated by the host immune system can restrict intracellular parasite entry and growth. While this burst leads to the induction of antioxidative enzymes, the molecular mechanisms and the consequences of this counter-response on the life of intracellular human parasites are largely unknown. The transcription factor NF-E2-related factor (NRF2) could be a key mediator of antioxidant signaling during infection due to the entry of parasites. Here, we showed that NRF2 was strongly upregulated in infection with the human Leishmania protozoan parasites, its activation was dependent on a NADPH oxidase 2 (NOX2) and SRC family of protein tyrosine kinases (SFKs) signaling pathway and it reprogrammed host cell metabolism. In inflammatory leishmaniasis caused by a viral endosymbiont inducing TNF-α in chronic leishmaniasis, NRF2 activation promoted parasite persistence but limited TNF-α production and tissue destruction. These data provided evidence of the dual role of NRF2 in protecting both the invading pathogen from reactive oxygen species and the host from an excess of the TNF-α destructive pro-inflammatory cytokine.

Cytokines and metabolic regulation: A framework of bidirectional influences affecting Leishmania infection

Leishmania, a protozoan parasite inflicting the complex of diseases called Leishmaniases, resides and replicates as amastigotes within mammalian macrophages. As macrophages are metabolically highly active and can generate free radicals that can destroy this parasite, Leishmania also devise strategies to modulate the host cell metabolism. However, the metabolic changes can also be influenced by the anti-leishmanial immune response mediated by cytokines. This bidirectional, dynamic and complex metabolic coupling established between Leishmania and its host is the result of a long co-evolutionary process. Due to the continuous alterations imposed by the host microenvironment, such metabolic coupling continues to be dynamically regulated. The constant pursuit and competition for nutrients in the host-Leishmania duet alter the host metabolic pathways with major consequences for its nutritional reserves, eventually affecting the phenotype and functionality of the host cell. Altered phenotype and functions of macrophages are particularly relevant to immune cells, as perturbed metabolic fluxes can crucially affect the activation, differentiation, and functions of host immune cells. All these changes can deterministically direct the outcome of an infection. Cytokines and metabolic fluxes can bidirectionally influence each other through molecular sensors and regulators to dictate the final infection outcome. Our studies along with those from others have now identified the metabolic nodes that can be targeted for therapy.

Of Drugs and Trypanosomatids: New Tools and Knowledge to Reduce Bottlenecks in Drug Discovery

Leishmaniasis (Leishmania species), sleeping sickness (Trypanosoma brucei), and Chagas disease (Trypanosoma cruzi) are devastating and globally spread diseases caused by trypanosomatid parasites. At present, drugs for treating trypanosomatid diseases are far from ideal due to host toxicity, elevated cost, limited access, and increasing rates of drug resistance. Technological advances in parasitology, chemistry, and genomics have unlocked new possibilities for novel drug concepts and compound screening technologies that were previously inaccessible. In this perspective, we discuss current models used in drug-discovery cascades targeting trypanosomatids (from in vitro to in vivo approaches), their use and limitations in a biological context, as well as different examples of recently discovered lead compounds.