Pretreatment of macrophages with the combination of IFN-gamma and IL-12 induces resistance to Leishmania major at the early phase of infection

Progress of ursolic acid on the regulation of macrophage: summary and prospect

Ursolic acid (UA), a prevalent pentacyclic triterpenoid found in numerous fruits and herbs, has garnered significant attention for its vital role in anti-inflammatory processes and immune regulation. The study of immune cells has consistently been a focal point, particularly regarding macrophages, which play crucial roles in antigen presentation, immunomodulation, the inflammatory response, and pathogen phagocytosis. This paper reveals the underlying regulatory effects of UA on the function of macrophages and the specific therapeutic effects of UA on a variety of diseases. Owing to the superior effect of UA on macrophages, different types of macrophages in different tissues have been described. Through the multifaceted regulation of macrophage function, UA may provide new ideas for the development of novel anti-inflammatory and immunomodulatory drugs. However, to facilitate its translation into actual medical means, the specific mechanism of UA in macrophages and its clinical application still need to be further studied.

Artemisinin: An Anti-Leishmania Drug that Targets the Leishmania Parasite and Activates Apoptosis of Infected Cells

Leishmaniasis is a relevant disease worldwide due to its presence in many countries and an estimated prevalence of 10 million people. The causative agent of this disease is the obligate intracellular parasite Leishmania which can infect different cell types. Part of its success depends on its ability to evade host defense mechanisms such as apoptosis. Apoptosis is a finely programmed process of cell death in which cells silently dismantle and actively participate in several processes such as immune response, differentiation, and cell growth. Leishmania has the ability to delay its initiation to persist in the cell. It has been well documented that different Leishmania species target different pathways that lead to apoptosis of cells such as macrophages, neutrophils, and dendritic cells. In many cases, the observed anti-apoptotic effect has been associated with a significant reduction in caspase-3 activity. Leishmania has also been shown to target several pathways involved in apoptosis such as MAPK, PI3K/Akt, and the antiapoptotic protein Bcl-xL. Understanding the strategies used by Leishmania to subvert the defense mechanisms of host cells, particularly apoptosis, is very relevant for the development of therapies and vaccines. In recent years, the drug artemisinin has been shown to be effective against several parasitic diseases. Its role against Leishmania may be promising. In this review, we provide important aspects of the disease, the strategies used by the parasite to suppress apoptosis, and the role of artemisinin in Leishmania infection.

Cytokines and Signaling Networks Regulating Disease Outcomes in Leishmaniasis

Cytokines play crucial roles in commencing and coordinating the organized recruitment and activation of immune cells during infection. These molecular regulators play an important part in deciding the fate of disease outcomes in leishmaniasis, a parasitic disease of tropical and subtropical countries. T helper 1 (Th1) cell-mediated inflammatory cytokines usually play a host-protective role, while T helper 2 (Th2) cell activation produces an anti-inflammatory milieu necessary for parasite survival. It is noteworthy that in such a multifaceted disease, the role played by any particular cytokine cannot be generalized as either beneficial or detrimental. For example, a "host-favorable" cytokine in one form of the disease has been found to be "pathogen friendly" in another form of leishmaniasis. On the other hand, the complex signaling network regulating the production of cytokines is further complicated by the nature of the host as well as the presence of other cytokines in the milieu. The present review focuses on the differential roles played by cytokines and the intricate signaling network responsible for the regulation of such cytokines during infection by different species of Leishmania. While many more studies are required in the future to better understand the role of these molecules in both animal models and patient samples, current studies indicate that these molecules are potential candidates to be targeted for therapy against this deadly disease.

Immunotherapeutic effects of Glycyrrhiza glabra and Glycyrrhizic Acid on Leishmania major-infection BALB/C mice

Treatment of cutaneous leishmaniasis (CL) is a public health problem in endemic areas. The objective of the current study was to investigate the immunotherapeutic activities of the hydroalcoholic extract of Glycyrrhiza glabra (HEG) and glycyrrhizic acid (GA) in the treatment of Leishmania major (L. major)-infected BALB/c mice. In this study, the effect of HEG and GA was checked in vitro on growth of L. major promastigote and amastigote using MTT assay and microscopic counting, respectively. For in vivo experiment, the lesion induced by L. major on BALB/c mice were treated intraperitoneally with HEG, GA, meglumine antimoniate or phosphate buffer saline (negative control) for one month. Then, the lesion development and the parasite burden of the lymph node was assessed, the cytokine response (IFN-γ and IL-4) to Leishmania antigens was evaluated using ELISA method. The results showed that HEG and GA significantly inhibited the growth of L. major promastigotes and amastigotes, the lesion development, parasite burden in the lymph nodes, level of IFN-γ and the ratio of IFN-γ/IL-4 in HEG, GA and meglumine antimoniate-treated mice were significantly higher compared with the negative control group, there was no difference between the HEG, GA and meglumine antimoniate group. It is concluded that hydroalcoholic extract of G. glabra and glycyrrhizic acid showed therapeutic and immunomodulatory effects on L. major-infected BALB/c mice.

Treatment with triterpenic fraction purified from Baccharis uncinella leaves inhibits Leishmania (Leishmania) amazonensis spreading and improves Th1 immune response in infected mice

The current medications used to treat leishmaniasis have many side effects for patients; in addition, some cases of the disease are refractory to treatment. Therefore, the search for new leishmanicidal compounds is indispensable. Recently, it was demonstrated that oleanolic- and ursolic-containing fraction from Baccharis uncinella leaves eliminated the promastigote and amastigote forms of Leishmania (Leishmania) amazonensis and L. (Viannia) braziliensis without causing toxic effects for J774 macrophages. Thus, the aim of the present work was to characterize the therapeutic effect of the triterpenic fraction in L. (L.) amazonensis-infected BALB/c mice. Oleanolic- and ursolic acid-containing fraction was extracted from B. uncinella leaves using organic solvents and chromatographic procedures. L. (L.) amazonensis-infected BALB/c mice were treated intraperitoneally with triterpenic fraction during five consecutive days with 1.0 and 5.0 mg/kg of triterpenic fraction, or with 10.0 mg/kg of amphotericin B drug. Groups of mice treated with the triterpenic fraction, presented with decreased lesion size and low parasitism of the skin-both of which were associated with high amounts of interleukin-12 and interferon gamma. The curative effect of this fraction was similar to amphotericin B-treated mice; however, the final dose, required to eliminate amastigotes, was lesser than amphotericin B. Moreover, triterpenic fraction did not cause microscopic alterations in liver, spleen, heart, lung, and kidney of experimental groups. This work suggests that this fraction possesses compounds that are characterized by leishmanicidal and immunomodulatory activities. From this perspective, the triterpenic fraction can be explored as a new therapeutic agent for use against American Tegumentar Leishmaniasis.

Old World cutaneous leishmaniasis: diagnosis and treatment

Cutaneous leishmaniasis is a major world health problem. Diagnosis is suspected on evocative clinical presentation in patients living in or coming from endemic areas. Several methods have been used. The smear is a simple investigation used in endemic regions. The culture enables to identify the specimen. PCR has a high sensitivity. Montenegro's reaction is used in the epidemiological study. Pentavalent antimony derivatives remain the mainstay of systemic treatment. Their efficiency is well established. Their toxicity should be researched. Other treatments can be utilized, such as miltefosine. Local therapy is used in uncomplicated lesions. Injections of the pentavalent antimony derivate, cryotherapy and paromomycin ointmentsis are important options and should be used more frequently in Old World leishmaniasis.

Novel immunomodulatory function of 1,3,4-thiadiazole derivatives with leishmanicidal activity

OBJECTIVES

Previously, some nitroheteroaryl-1,3,4-thiadiazole derivatives were identified to have potent activity against Leishmania sp. The present aim was to complete the in vitro analysis, thereby investigating the in vivo efficiency of the analogues 15a, 21a and 21b against infected BALB/c mice.

METHODS

Following parasite inoculation and intraperitoneal drug administration (5 and 20 mg/kg/day) for 5 days, the course and size of cutaneous lesions, histopathology of the liver, parasite loads in the spleen through limiting dilution assay as well as spleen cell activation assays through cytokine secretion profiles were studied in BALB/c mice, over a period of 23 and 30 days post-drug injections.

RESULTS

The analogues significantly decreased lesion size and progression of infection in the liver and spleen, and were associated with granuloma formation, which correlates with disease regression in the liver of murine hosts. Moreover, the analogues had immunomodulatory effects, stimulating interferon-γ expression and suppressing interleukin-10 and interleukin-5 production, favouring type-1 immune responses and resolution of the parasitic infection.

CONCLUSIONS

Our results highlight marked differences between the responses of key anatomical organs to the thiadiazole derivatives in comparison with the current antileishmanial drug, meglumine antimoniate. The in vivo observations provide further evidence on the efficiency of the compounds for Leishmania treatment. The immunomodulatory function plays an essential role in enhancing cell-mediated immunity for complete clearance of the pathogen.

Leishmania (Viannia) shawi purified antigens confer protection against murine cutaneous leishmaniasis

OBJECTIVE

Leishmania (Viannia) shawi was characterized only recently, and few studies concerning the immunogenic and protective properties of its antigens have been performed. The present study aimed to evaluate the protective potential of the five antigenic fractions isolated from L. (V.) shawi promastigotes in experimental cutaneous leishmaniasis.

MATERIALS AND METHODS

Soluble antigen from L. (V.) shawi promastigotes was submitted to reverse phase HPLC to purify F1, F2, F3, F4 and F5 antigens. BALB/c mice were immunized once a week for two consecutive weeks by subcutaneous routes in the rump, using 25 μg protein. After 1 week, groups were challenged in the footpad with L. (V.) shawi promastigotes. After 8 weeks, those same mice were sacrificed and parasite burden as well as the cellular and humoral immune responses were evaluated.

RESULTS

F1 and F5-immunized mice restrained lesion progression and parasite load in the skin. However, only the F1 group was able to control the parasitism in lymph nodes, which was associated with low IL-4 and high IFN-γ production; IgG2a isotype was increased in this group. Immunizations with F2, F3 and F4 antigens did not protect mice.

CONCLUSION

The capability of antigens to restrain IL-4 levels and increase IFN-γ was associated with protection, such as in immunization using F1 antigen.

Exacerbation of Leishmania (Viannia) shawi infection in BALB/c mice after immunization with soluble antigen from amastigote forms

The present study aimed to evaluate the effects of immunization with soluble amastigote (AmaAg) and promastigote (ProAg) antigens from Leishmania (Viannia) shawi on the course of infection in BALB/c mice. After immunization with AmaAg, the challenged group showed greater lesion size and parasite load in the skin and lymph nodes, associated with diminished interleukin (IL)-2, IL-4, IL-10, interferon (IFN)-γ and nitrate levels in the supernatant of lymph node cell cultures, together with increases in transforming growth factor (TGF)-β concentrations and humoral immune response. In contrast, immunization with ProAg led to smaller lesion size with reduced numbers of viable parasites in the skin. Protection was associated with increases in IL-12, IFN-γ, TGF-β and nitrates and decreases in IL-4 and IL-10 levels. Concerning humoral immune response, a significant reduction in anti-leishmania immunoglobulin G was verified in the ProAg-challenged group. Analysis of these results suggests that AmaAg induced a suppressive cellular immune response in mice, favouring the spread of infection, whereas ProAg induced partial protection associated with increased cellular immune response.