Production of nitric oxide by murine macrophages induced by lipophosphoglycan of Leishmania major

TGF-β Targeted by miR-27a Modulates Anti-Parasite Responses of Immune System

Background

Immune cells and their secreted cytokines are known as the first barrier against pathogens. Leishmania major as an intracellular protozoan produces anti-inflammatory cytokines that lead to proliferation and survival of the parasite in the macrophages. miRNAs are small non-coding RNA molecules that regulate mRNAs expression. We aimed to investigate the relationship between the expression of TGF-β and a bioinformatically candidate miRNA, in leishmaniasis as a model of TGF-β overexpression.

Methods

The miRNAs that target TGF-β -3'UTR were predicted and scored by bioinformatic tools. After cloning of TGF-β-3'UTR in psi-CHECK ™- 2 vector, targeting validation was confirmed using Luciferase assay. After miRNA mimic transfection, the expression of miR-27a, TGF-β, as well as Nitric Oxide concentration was evaluated.

Results

miR-27a received the highest score for targeting TGF-β in bioinformatic predictions. Luciferase assay confirmed that miR-27a is targeting TGF-β-3'UTR, since miR-27a transfection decreased the luciferase activity. After miRNA transfection, TGF-β expression and Nitric Oxide concentration were declined in L. major infected macrophages.

Conclusion

Bioinformatic prediction, luciferase assay, and miRNA transfection results showed that miR-27a targets TGF-β. Since miRNA and cytokine-base therapies are developing in infectious diseases, finding and validating miRNAs targeting regulatory cytokines can be a novel strategy for controlling and treating leishmaniasis.

Metformin partially reverses the inhibitory effect of co-culture with ER-/PR-/HER2+ breast cancer cells on biomarkers of monocyte antitumor activity

BACKGROUND

Immune activities of monocytes (MOs) can be altered within the microenvironment of solid malignancies, including breast cancer. Metformin (1,1-dimethylbiguanide hydrochloride, MET), has been shown to decrease tumor cell proliferation, but its effects have yet to be explored with respect to MOs (monocytes) activity during their crosstalk with breast cancer cells. Here, we investigated the effects of MET on overall phenotypic functional activities, including cellular immunometabolism and protective redox signaling based-biomarkers, intracellular free calcium ions (ifCa2+), phagocytosis and co-operative cytokines (IFN-γ and IL-10) of autologous MOs before and during their interplay with primary ER-/PR-/HER2+ breast cancer cells.

METHODS

Human primary breast cancer cells were either cultured alone or co-cultured with autologous MOs before treatment with MET.

RESULTS

MET downregulated breast cancer cell proliferation and phagocytosis, while having no significant effect on the ratio of phosphorylated Akt (p-Akt) to total Akt. Additionally, we observed that, in the absence of MET treatment, the levels of lactate dehydrogenase (LDH)-based cytotoxicity, catalase, ifCa2+, IL-10 and arginase activity were significantly reduced in co-cultures compared to levels in MOs cultured alone whereas levels of inducible nitric oxide synthase (iNOS) activity were significantly increased. In contrast, MET treatment reduced the effects measured in co-culture on the levels of LDH-based cytotoxicity, arginase activity, catalase, ifCa2+, and IFN-γ. MET also induced upregulation of both iNOS and arginase in MO cells, although the increase did not reach significant difference for iNOS activity. Moreover, MET induced a robust increase of superoxide dismutase (SOD) activity in MOs, but not in MOs co-cultured with breast cancer cells. Furthermore, MET markedly upregulated the levels of IFN-γ production and downregulated those of IL-10 in isolated MOs, while inducing a slight opposing up-regulation of IL-10 production in co-cultures.

CONCLUSIONS

Our results show that the biomarkers of phenotypic functional activities of MOs are modified after co-culturing with primary human breast cancer cells. Treatment of co-cultures with MET resulted in increased release of antitumor cytokine IFN-γ and ifCa2+, and increased cell necrosis during breast cancer cells-MOs crosstalk.

Review on the Role of Host Immune Response in Protection and Immunopathogenesis during Cutaneous Leishmaniasis Infection

Cutaneous leishmaniasis (CL) is a major public health problem worldwide and spreads to human via the bite of sand flies during blood meal. Following its inoculation, the promastigotes are immediately taken up by phagocytic cells and these leishmania-infected host cells produce proinflammatory cytokines that activate other immune cells and these infected host cells produce more cytokines and reactive nitrogen and oxygen species for efficient control of leishmania infection. Many experimental studies showed that resistance to infection with leishmania paraites is associated with the production of proinflammatory cytokines and activation of CD4⁺ Th1 response. On the other hand, vulnerability to this parasitic infection is correlated to production of T helper 2 cytokines that facilitate persistence of parasites and disease progression. In addition, some studies have also indicated that CD8⁺ T cells play a vital role in immune defense through cytokine production and their cytotoxic activity and excessive production of proinflammatory mediators promote amplified recruitment of cells. This could be correlated with excessive inflammatory reaction and ultimately resulted in tissue destruction and development of immunopathogenesis. Thus, there are contradictions regarding the role of immune responses in protection and immunopathogenesis of CL disease. Therefore, the aim of this paper was to review the role of host immune response in protection and its contribution to disease severity for CL infection. In order to obtain more meaningful data regarding the nature of immune response to leishmania, further in-depth studies focused on immune modulation should be conducted to develop better therapeutic strategies.

Future Prospects in the Treatment of Parasitic Diseases: 2-Amino-1,3,4-Thiadiazoles in Leishmaniasis

Neglected tropical diseases affect the lives of a billion people worldwide. Among them, the parasitic infections caused by protozoan parasites of the Trypanosomatidae family have a huge impact on human health. Leishmaniasis, caused by Leishmania spp., is an endemic parasitic disease in over 88 countries and is closely associated with poverty. Although significant advances have been made in the treatment of leishmaniasis over the last decade, currently available chemotherapy is far from satisfactory. The lack of an approved vaccine, effective medication and significant drug resistance worldwide had led to considerable interest in discovering new, inexpensive, efficient and safe antileishmanial agents. 1,3,4-Thiadiazole rings are found in biologically active natural products and medicinally important synthetic compounds. The thiadiazole ring exhibits several specific properties: it is a bioisostere of pyrimidine or benzene rings with prevalence in biologically active compounds; the sulfur atom increases lipophilicity and combined with the mesoionic character of thiadiazoles imparts good oral absorption and good cell permeability, resulting in good bioavailability. This review presents synthetic 2-amino-1,3,4-thiadiazole derivatives with antileishmanial activity. Many reported derivatives can be considered as lead compounds for the synthesis of future agents as an alternative to the treatment of leishmaniasis.

A new approach for development of vaccine against visceral leishmaniasis: Lipophosphoglycan and polyacrylic acid conjugates

OBJECTIVE

To determine the antileishmanial vaccine effectiveness of lipophosphoglycan (LPG) and polyacrylic acids (PAA) conjugates on in vivo mice models.

METHODS

LPG molecule was isolated and purified from large-scale Leishmania donovani parasite culture. Protection efficacies of LPG alone, in combination with Freund's adjuvant, in a physical mixture and in conjugate (consisting of various LPG concentrations) with PAA, were comparatively determined by various techniques, such as cultivation with the micro-culture method, assessment of in vitro infection rates of peritoneal macrophages, determination of parasite load in liver with Leishman-Donovan Units, and detection of cytokine responses.

RESULTS

Obtained results demonstrated that the highest vaccine-mediated immune protection was provided by LPG-PAA conjugate due to all parameters investigated. According to the Leishman-Donovan Units results, the sharpest decline in parasite load was seen with a ratio of 81.17% when 35 μg LPG containing conjugate was applied. This value was 44.93% for the control group immunized only with LPG. Moreover, decreases in parasite load were 53.37%, 55.2% and 65.8% for the groups immunized with 10 μg LPG containing LPG-PAA conjugate, a physical mixture of the LPG-PAA, and a mixture of LPG + Freund's adjuvant, respectively. Furthermore, cytokine results supported that Th1 mediated protection occurred when mice were immunized with LPG-PAA conjugate.

CONCLUSIONS

It has been demonstrated in this study that conjugate of LPG and PAA has an antileishmanial vaccine effect against visceral leishmaniasis. In this respect, the present study may lead to new vaccine approaches based on high immunogenic LPG molecule and adjuvant polymers in fighting against Leishmania infection.

Reactive oxygen species and nitric oxide in cutaneous leishmaniasis

Cutaneous leishmaniasis affects millions of people around the world. Several species of Leishmania infect mouse strains, and murine models closely reproduce the cutaneous lesions caused by the parasite in humans. Mouse models have enabled studies on the pathogenesis and effector mechanisms of host resistance to infection. Here, we review the role of nitric oxide (NO), reactive oxygen species (ROS), and peroxynitrite (ONOO⁻) in the control of parasites by macrophages, which are both the host cells and the effector cells. We also discuss the role of neutrophil-derived oxygen and nitrogen reactive species during infection with Leishmania. We emphasize the role of these cells in the outcome of leishmaniasis early after infection, before the adaptive T_h-cell immune response.

Inhibition of Murine Systemic Leishmaniasis by Acetyl Salicylic Acid via Nitric Oxide Immunomodulation

BACKGROUND

The purpose of this study was to evaluate antileishmanial effects of ASA via NO pathway in Leishmania major infected Balb/c mice. Moreover, toxicity and pathological consequences of ASA administration were investigated.

METHODS

Balb/c mice were infected with L. major and ASA was inoculated orally after lesion appearance for its ability to modulate NO and to modify Leishmania infection in host, in order to evaluate the effects of NO production on size and lesion macroscopy, delay of lesion formation and proliferation of amastigotes inside macrophages. Liver, spleen, and lymph nodes were also studied as target organs to detect amastigotes. In addition, plasma was investigated for NO induction using Griess microassay.

RESULTS

ASA increased NO production in plasma of both naïve and Leishmania test groups at the ultimate of the experimental period. A decline was observed in proliferation of amastigotes inside macrophages of test group when compared with control one. ASA reduced lesion size, inhibited Leishmania visceralisation in spleen, lymph node, and decreased hepato/splenomegaly in ASA treated animals.

CONCLUSIONS

Some antileishmanial effects of ASA by NO-modulation were indicated during systemic leishmaniasis in mice. Despite slight effects on lesion size, ASA decreased parasite visceralization in target organs and declined their proliferation inside macrophages. Therefore, ASA may be indicated to inhibit systemic leishmaniasis via NO pathway in mice model.

Antileishmanial activity of 1,3,4-thiadiazolium-2-aminide in mice infected with Leishmania amazonensis

The efficacy of two mesoionic derivatives (MI-H-H and MI-4-OCH(3)) was evaluated in CBA/J mice infected with Leishmania amazonensis. Treatment with these compounds demonstrated that the MI-4-OCH(3) derivative and the reference drug meglumine antimoniate (Glucantime) presented significant activity relative to an untreated control. No apparent hepatic or renal toxicity due to these mesoionic compounds was found.

Pharmacological evaluation of anti-leishmanial activity by in vivo nitric oxide modulation in Balb/c mice infected with Leishmania major MRHO/IR/75/ER: An Iranian strain of cutaneous leishmaniasis

Cutaneous leishmaniasis with a variation in its clinical signs is still one of the health problems in the world, region and Iran. Immune responses against leishmania consist of cytokines, immune cells and mediators. Macrophages participate actively in the inflammatory response by releasing chemokines and mediators including nitric oxide (NO) and reactive oxygen and nitrogen intermediates. This study investigates whether NO had anti-leishmanial effects and/or mediated pathology in mice infected with Leishmania major MRHO/IR/75/ER (IR/75). NO inducer lipopolysaccharide (LPS) and NO donor S-nitrosoglutathione (SNOG) were used for their ability to increase RNI and to modify leishmania infection in susceptible Balb/c mice, in order to evaluate the effects of NO production on size and lesion macroscopy, delay of lesion formation and proliferation of amastigotes inside macrophages. Liver, spleen and lymph nodes were also studied as target organs to detect amastigotes. In addition to plasma, liver and spleen suspensions were investigated for NO induction by using Griess microassay. Statistical analysis of data revealed an association between increases in NO level with the pathology of disease in Balb/c mice infected with L. major IR/75. The survival of leishmania parasite inside the macrophages and its proliferation was affected by LPS and SNOG-treatments. An inconsistent relationship was evident between the NO modulation and pathological changes in treated Balb/c mice infected with L. major IR/75.