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

Host P2X7R-p38MAPK axis mediated intra-macrophage leishmanicidal activity of Spergulin-A

Current drugs are inefficient for the treatment of visceral leishmaniasis an immunosuppressive ailment caused by Leishmania donovani. Regrettably, there is no plant-origin antileishmanial drug present. P2X₇R is constitutively present on macrophage surfaces and can be a putative therapeutic target in intra-macrophage pathogens with function attributes towards inflammation, host cell apoptosis, altered redox, and phagolysosomal maturation by activating p₃₈MAPK. Here we demonstrated that the initial interaction of Spergulin-A (Sp A), a triterpenoid saponin with RAW 264.7 macrophages was mediated through P2X₇R involving the signaling cascade intermediates Ca⁺⁺, p₃₈MAPK, and NF-κβ. Phospho (P)-p38MAPK involvement is shown to have specific and firm importance in leishmanial killing with increased NF-κβp65. Phago-lysosomal maturation by Sp A also campaigns for another contribution of P2X₇R. In vivo evaluation of the anti-leishmanial activity of Sp A was monitored through expression analyses of P2X₇R, P-p38MAPK, and NF-κβp65 in murine spleen and bone-marrow macrophages and supported Sp A being a natural compound of leishmanicidal functions which acted through the P2X₇R-p38MAPK axis.

The promising therapeutic potentials of ginsenosides mediated through p38 MAPK signaling inhibition

The p38 mitogen-activated protein kinases (p38 MAPK) is a 38kD polypeptide recognized as the target for many potential anti-inflammatory agents. Accumulating evidence indicates that p38 MAPK could perform many roles in human disease pathophysiology. Therefore, great therapeutic benefits can be attained from p38 MAPK inhibitors. Ginseng is an exceptionally valued medicinal plant of the family Araliaceae (Panax genus). Recently, several studies targeted the therapeutic effects of purified individual ginsenoside, the most significant active ingredient of ginseng, and studied its particular molecular mechanism(s) of action rather than whole-plant extracts. Interestingly, several ginsenosides: ginsenosides compound K, F1, Rb1, Rb3, Rc, Rd, Re, Rf, Rg1, Rg2, Rg3, Rg5, Rh1, Rh2, Ro, notoginsenoside R1, and protopanaxadiol have shown to possess great therapeutic potentials mediated by their ability to downregulate p38 MAPK signaling in different cell lines and experimental animal models. Our review compiles the research findings of various ginsenosides as potent anti-inflammatory agents, highlighting the crucial role of p38 MAPK suppression in their pharmacological actions. In addition, in silico studies were conducted to explore the probable binding of these ginsenosides to p38 MAPK. The results obtained proposed p38 MAPK involvement in the beneficial pharmacological activities of ginsenosides in different ailments.

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p38 MAPK plays many roles in human disease pathophysiology. Therefore, great therapeutic benefits can be attained from p38 MAPK inhibitors.

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Several ginsenosides showed to possess great therapeutic potentials mediated by its ability to downregulate p38 MAPK signaling.

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in silico ​studies were conducted to explore the binding of these ginsenosides to p38 MAPK and evidenced the promising their inhibitory effect.

Gene expression patterns associated with Leishmania panamensis infection in macrophages from BALB/c and C57BL/6 mice

Leishmania parasites can trigger different host immune responses that result in varying levels of disease severity. The C57BL/6 and BALB/c mouse strains are among the host models commonly used for characterizing the immunopathogenesis of Leishmania species and the possible antileishmanial effect of novel drug candidates. C57BL/6 mice tend to be resistant to Leishmania infections, whereas BALB/c mice display a susceptible phenotype. Studying species-specific interactions between Leishmania parasites and different host systems is a key step to characterize and validate these models for in vivo studies. Here, we use RNA-Seq and differential expression analysis to characterize the transcriptomic profiles of C57BL/6 and BALB/c peritoneal-derived macrophages in response to Leishmania panamensis infection. We observed differences between BALB/c and C57BL/6 macrophages regarding pathways associated with lysosomal degradation, arginine metabolism and the regulation of cell cycle. We also observed differences in the expression of chemokine and cytokine genes associated with regulation of immune responses. In conclusion, infection with L. panamensis induced an inflammatory gene expression pattern in C57BL/6 macrophages that is more consistently associated with a classic macrophage M1 activation, whereas in BALB/c macrophages a gene expression pattern consistent with an intermediate inflammatory response was observed.

Cytokine Gene Expression Alterations in Human Macrophages Infected by Leishmania major

Objective

Leishmaniasis is caused by members of the Leishmania species and constitute a group of infective diseases that range from cutaneous lesions to lethal visceral forms. In infected persons, macrophages recognize and eliminate the parasites via phagocytosis. In order to change a hostile environment into an environment adequate for survival and reproduction, the engulfed Leishmania species needs to modulate the function of its host macrophage. The expression patterns of cytokine genes such as interleukin-12 (IL-12), tumour necrosis factor-alpha (TNF-α), IL-1, and interferon-gamma (IFNγ) represent the immune response. In this study, we employed an RNA-seq approach for human monocyte-derived macrophages infected with Leishmania major (L. major) to decipher cytokine gene expression alterations in host macrophages.

Materials and Methods

In this descriptive study, human monocytes were isolated by magnetic activated cell sorting (MACS) and cultured in the presence of monocyte colony stimulating factor (M-CSF) to obtain the macrophages. Monocyte-derived macrophages were then co-cultured with metacyclic promastigotes of L. major for 4 hours. RNA isolation was performed using TRIzol reagent. RNA sequencing was performed using the Illumina sequencing platforms. Gene expression analysis was performed using a Bioconductor DESeq2 package.

Results

Our data revealed significant changes in immune response gene expressions in macrophages infected with L. major, with an up-regulation of cytokines and mostly down-regulation of their receptors.

Conclusion

The obtained data could shed more light on the biology of L. major and how the host cell responds to leishmaniasis.

Intracellular anti-leishmanial effect of Spergulin-A, a triterpenoid saponin of Glinus oppositifolius

Background

Many of present chemotherapeutics are inadequate and also resistant against visceral leishmaniasis (VL), an immunosuppressive ailment caused by Leishmania donovani. Despite the interest in plant-based drug development, no antileishmanial drugs from plant source are currently available. Glinus oppositifolius had been reported in favor of being immune modulators along with other traditional uses. Novel anti-VL therapies can rely on host immune-modulation with associated leishmanicidal action.

Objective

Discovery of novel plant-based antileishmanial compound from G. oppositifolius having permissible side effects.

Methods

With this rationale, an n-BuOH fraction of the methanolic extract of the plant and obtained triterpenoid saponin Spergulin-A were evaluated against acellular and intracellular L. donovani. Immunostimulatory activity of them was confirmed by elevated TNF-α and extracellular NO production from treated MФs and was found nontoxic to the host cells. Identification and structure confirmation for isolated Spergulin-A was performed by ESI-MS,¹³C, and ¹H NMR.

Results

Spergulin-A was found ineffective against the acellular forms while, against the intracellular parasites at 30 μg/mL, the reduction was 92.6% after 72 hrs. Spergulin-A enhanced ROS and nitric oxide (NO) release and changes in Gp91-phox, i-NOS, and pro and anti-inflammatory cytokines elaborated its intracellular anti-leishmanial activity.

Conclusion

The results supported that G. oppositifolius and Spergulin-A can potentiate new lead molecules for the development of alternative drugs against VL.

Functional aspects, phenotypic heterogeneity, and tissue immune response of macrophages in infectious diseases

Macrophages are a functionally heterogeneous group of cells with specialized functions depending not only on their subgroup but also on the function of the organ or tissue in which the cells are located. The concept of macrophage phenotypic heterogeneity has been investigated since the 1980s, and more recent studies have identified a diverse spectrum of phenotypic subpopulations. Several types of macrophages play a central role in the response to infectious agents and, along with other components of the immune system, determine the clinical outcome of major infectious diseases. Here, we review the functions of various macrophage phenotypic subpopulations, the concept of macrophage polarization, and the influence of these cells on the evolution of infections. In addition, we emphasize their role in the immune response in vivo and in situ, as well as the molecular effectors and signaling mechanisms used by these cells. Furthermore, we highlight the mechanisms of immune evasion triggered by infectious agents to counter the actions of macrophages and their consequences. Our aim here is to provide an overview of the role of macrophages in the pathogenesis of critical transmissible diseases and discuss how elucidation of this relationship could enhance our understanding of the host-pathogen association in organ-specific immune responses.

Biochemical analysis of leishmanial and human GDP-Mannose Pyrophosphorylases and selection of inhibitors as new leads

Leishmaniases are an ensemble of diseases caused by the protozoan parasite of the genus Leishmania. Current antileishmanial treatments are limited and present main issues of toxicity and drug resistance emergence. Therefore, the generation of new inhibitors specifically directed against a leishmanial target is an attractive strategy to expand the chemotherapeutic arsenal. GDP-Mannose Pyrophosphorylase (GDP-MP) is a prominent therapeutic target involved in host-parasite recognition which has been described to be essential for parasite survival. In this work, we produced and purified GDP-MPs from L. mexicana (LmGDP-MP), L. donovani (LdGDP-MP), and human (hGDP-MP), and compared their enzymatic properties. From a rationale design of 100 potential inhibitors, four compounds were identified having a promising and specific inhibitory effect on parasite GDP-MP and antileishmanial activities, one of them exhibits a competitive inhibition on LdGDP-MP and belongs to the 2-substituted quinoline series.