Nitazoxanide Inhibits the Bifunctional Enzyme GlG6PD::6PGL of Giardia lamblia: Biochemical and In Silico Characterization of a New Druggable Target

Giardiasis, which is caused by Giardia lamblia infection, is a relevant cause of morbidity and mortality worldwide. Because no vaccines are currently available to treat giardiasis, chemotherapeutic drugs are the main options for controlling infection. Evidence has shown that the nitro drug nitazoxanide (NTZ) is a commonly prescribed treatment for giardiasis; however, the mechanisms underlying NTZ's antigiardial activity are not well-understood. Herein, we identified the glucose-6-phosphate::6-phosphogluconate dehydrogenase (GlG6PD::6PGL) fused enzyme as a nitazoxanide target, as NTZ behaves as a GlG6PD::6PGL catalytic inhibitor. Furthermore, fluorescence assays suggest alterations in the stability of GlG6PD::6PGL protein, whereas the results indicate a loss of catalytic activity due to conformational and folding changes. Molecular docking and dynamic simulation studies suggest a model of NTZ binding on the active site of the G6PD domain and near the structural NADP⁺ binding site. The findings of this study provide a novel mechanistic basis and strategy for the antigiardial activity of the NTZ drug.

Extracellular vesicles from Mycobacterium tuberculosis-infected neutrophils induce maturation of monocyte-derived dendritic cells and activation of antigen-specific Th1 cells

Tuberculosis remains one of the leading public health problems in the world. The mechanisms that lead to the activation of the immune response against Mycobacterium tuberculosis (Mtb) have been extensively studied, with a focus on the role of cytokines as the main signals for immune cell communication. However, less is known about the role of other signals, such as extracellular vesicles (EVs), in the communication between immune cells, particularly during the activation of the adaptive immune response. In this study, we determined that EVs released by human neutrophils infected with Mtb (EV-Mtb) contained several host proteins that are ectosome markers. In addition, we demonstrated that EV-Mtb released after only 30 min of infection carried mycobacterial antigens and pathogen-associated molecular patterns, and we identified 15 mycobacterial proteins that were consistently found in high concentrations in EV-Mtb; these proteins contain epitopes for CD4 T cell activation. We found that EV-Mtb increased the expression of the co-stimulatory molecule CD80 and of the co-inhibitory molecule PD-L1 on immature monocyte-derived dendritic cells. We also found that immature and mature dendritic cells treated with EV-Mtb were able to induce IFN-γ production by autologous Mtb antigen-specific CD4 T cells, indicating that these EVs acted as antigen carriers and transferred mycobacterial proteins to the antigen-presenting cells. Our results provide evidence that EV-Mtb participate in the activation of the adaptive immune response against Mtb.

Effect of B-NIPOx in Experimental Trypanosoma cruzi Infection in Mice

Chagas disease is caused by Trypanosoma cruzi and represents a major public health problem, which is endemic in Latin America and emerging in the rest of the world. The two drugs that are currently available for its treatment, Benznidazole and Nifurtimox, are partially effective in the chronic phase of the disease. In this study, we designed and synthesized the benzyl ester of N-isopropyl oxamic acid (B-NIPOx), which is a non-polar molecule that crosses cell membranes. B-NIPOx is cleaved inside the parasite by carboxylesterases, releasing benzyl alcohol (a molecule with antimicrobial activity), and NIPOx, which is an inhibitor of α-hydroxy acid dehydrogenase isozyme II (HADH-II), a key enzyme in T. cruzi metabolism. We evaluated B-NIPOx cytotoxicity, its toxicity in mice, and its inhibitory activity on purified HADH-II and on T. cruzi homogenates. We then evaluated the trypanocidal activity of B-NIPOx in vitro and in vivo and its effect in the intestine of T. cruzi-infected mice. We found that B-NIPOx had higher trypanocidal activity on epimastigotes and trypomastigotes than Benznidazole and Nifurtimox, that it was more effective to reduce blood parasitemia and amastigote nests in infected mice, and that, in contrast to the reference drugs, it prevented the development of Chagasic enteropathy.

Pro-inflammatory monocytes are increased in Duchenne muscular dystrophy and suppressed with omega-3 fatty acids: A double-blind, randomized, placebo-controlled pilot study

BACKGROUND

Omega-3 long chain polyunsaturated fatty acids (LCPUFA) reduce circulating cytokines produced by monocytes. Nevertheless, whether the omega-3 LCPUFA regulate the monocytes and their cytokines in Duchenne muscular dystrophy (DMD) is unknown. The aim of this study was to evaluate whether circulating pro-inflammatory monocytes are increased and whether omega-3 LCPUFA selectively suppress these monocytes and their cytokines in patients with DMD.

METHODS

This was a double-blind, randomized, placebo-controlled pilot study carried out in patients with DMD supplemented with omega-3 LCPUFA (n = 6) or sunflower oils (placebo, n = 6) for 6 months. Monocytes and their cytokines were measured at baseline and after 1, 2, 3, and 6 months of supplementation.

RESULTS

The anti-inflammatory monocytes (median, [95% CI]) are increased at month 3 (-0.46 [-13.5-9.5] vs. 8.4 [5.5-12.5], p = 0.05) in the omega-3 LCPUFA group compared with the placebo group. The pro-inflammatory monocytes (-5.7 [-63.8-114.1] vs. -51.9 [-91.2 to -25.4], p = 0.026 and -16.4 [-50.8-50.6] vs. -57.9 [-86.9 to -18.5], p = 0.045 at months 3 and 6, respectively) and their cytokine interleukin 6 (-11.9 [-93.5-148.9] vs. -64.7 [-77.8 to -42.6], p = 0.019 at month 6) decreased in the omega-3 LCPUFA group compared with the placebo group. Pro-inflammatory monocytes decreased and anti-inflammatory monocytes were augmented (p < 0.05) during the 6 months of supplementation with omega-3 LCPUFA.

CONCLUSIONS

This pilot study suggests that supplementation with omega-3 LCPUFA could have a selective reductive effect on pro-inflammatory monocytes and their cytokines in patients with DMD. These findings also support the performance of studies in a significant population to explore the role of omega-3 LCPUFA on monocyte populations and their cytokines in patients with DMD. This research was registered at clinicaltrials.gov (NCT018264229).

Validation and Selection of New Reference Genes for RT-qPCR Analysis in Pediatric Glioma of Different Grades

Gliomas are heterogeneous, solid, and intracranial tumors that originate from glial cells. Malignant cells from the tumor undergo metabolic alterations to obtain the energy required for proliferation and the invasion of the cerebral parenchyma. The alterations in the expression of the genes related to the metabolic pathways can be detected in biopsies of gliomas of different CNS WHO grades. In this study, we evaluated the expression of 16 candidate reference genes in the HMC3 microglia cell line. Then, statistical algorithms such as BestKeeper, the comparative ΔC_T method, geNorm, NormFinder, and RefFinder were applied to obtain the genes most suitable to be considered as references for measuring the levels of expression in glioma samples. The results show that PKM and TPI1 are two novel genes suitable for genic expression studies on gliomas. Finally, we analyzed the expression of genes involved in metabolic pathways in clinical samples of brain gliomas of different CNS WHO grades. RT-qPCR analysis showed that in CNS WHO grade 3 and 4 gliomas, the expression levels of HK1, PFKM, GAPDH, G6PD, PGD1, IDH1, FASN, ACACA, and ELOVL2 were higher than those of CNS WHO grade 1 and 2 glioma biopsies. Hence, our results suggest that reference genes from metabolic pathways have different expression profiles depending on the stratification of gliomas and constitute a potential model for studying the development of this type of tumor and the search for molecular targets to treat gliomas.

Identification and In Silico Characterization of Novel Helicobacter pylori Glucose-6-Phosphate Dehydrogenase Inhibitors

Helicobacter pylori (H. pylori) is a pathogen that can remain in the stomach of an infected person for their entire life. As a result, this leads to the development of severe gastric diseases such as gastric cancer. In addition, current therapies have several problems including antibiotics resistance. Therefore, new practical options to eliminate this bacterium, and its induced affections, are required to avoid morbidity and mortality worldwide. One strategy in the search for new drugs is to detect compounds that inhibit a limiting step in a central metabolic pathway of the pathogen of interest. In this work, we tested 55 compounds to gain insights into their possible use as new inhibitory drugs of H. pylori glucose-6-phosphate dehydrogenase (HpG6PD) activity. The compounds YGC-1; MGD-1, MGD-2; TDA-1; and JMM-3 with their respective scaffold 1,3-thiazolidine-2,4-dione; 1H-benzimidazole; 1,3-benzoxazole, morpholine, and biphenylcarbonitrile showed the best inhibitory activity (IC₅₀ = 310, 465, 340, 204 and 304 μM, respectively). We then modeled the HpG6PD protein by homology modeling to conduct an in silico study of the chemical compounds and discovers its possible interactions with the HpG6PD enzyme. We found that compounds can be internalized at the NADP⁺ catalytic binding site. Hence, they probably exert a competitive inhibitory effect with NADP⁺ and a non-competitive or uncompetitive effect with G6P, that of the compounds binding far from the enzyme’s active site. Based on these findings, the tested compounds inhibiting HpG6PD represent promising novel drug candidates against H. pylori.

Interleukin 4 deficiency limits the development of a lupus-like disease in mice triggered by phospholipids in a non-bilayer arrangement

Non-bilayer phospholipids arrangements (NPAs) are transient molecular associations different from lipid bilayers. When they become stable, they can trigger a disease in mice resembling human lupus, which is mainly characterized by the production of anti-NPA IgG antibodies. NPAs are stabilized on liposomes or cell bilayers by the drugs procainamide or chlorpromazine, which produce drug-induced lupus in humans. Here, we evaluated the participation of the T_H 2 response, through its hallmark cytokine IL-4, on the development of the lupus-like disease in mice. Wild-type or IL-4 knockout BALB/c mice received liposomes bearing drug-induced NPAs, the drugs alone, or an anti-NPA monoclonal antibody (H308) to induce the lupus-like disease (the last two procedures stabilize NPAs on mice cells). IL-4 KO mice showed minor disease manifestations, compared to wild-type mice, with decreased production of anti-NPA IgG antibodies, no anti-cardiolipin, anti-histones and anticoagulant antibodies, and no kidney or skin lesions. In these mice, H308 was the only inducer of anti-NPA IgG antibodies. These findings indicate that IL-4 has a central role in the development of the murine lupus-like disease induced by NPA stabilization.

Lupresan, a new drug that prevents or reverts the formation of nonbilayer phospholipid arrangements that trigger a murine lupus resembling human lupus

Non-bilayer phospholipid arrangements (NPA) are lipid associations different from the bilayer, formed by the interactions of conic anionic lipids and divalent cations that produce an inverted micelle which is inserted between the lipid layers, so the polar heads of the outer lipids spread and expose new antigens. Since these structures are transient, they are not immunogenic, but if they are stabilized by drugs, such as chlorpromazine, they become immunogenic and induce anti-NPA antibodies that trigger a lupus-like disease in mice. Chloroquine is a drug used for the treatment of lupus; chloroquine has a quinoline ring and two positive charges that interact with conic anionic lipids and prevent or revert the formation of NPA. However, the polyamine spermidine is more effective, since it has three positive charges and interacts with more lipids, but polyamines cannot be used as drugs, because they are highly toxic. Here we report the design and synthesis of Lupresan, an analogous of chloroquine with its quinoline ring but with three positive charges. Lupresan is more effective in preventing or reverting the formation of NPA than chloroquine or spermidine, and as a consequence, it decreased auto-antibody titers and healed the malar rash in mice with lupus to a greater extent than chloroquine. A drug as Lupresan could be used for the treatment of human lupus.

Comparison of immune cells from germinal centers specific to protein or lipid antigens

Anti-lipid IgG antibodies can participate in the physiopathology of some autoimmune diseases. In our research group, we developed a mouse model of Lupus by the administration of liposomes bearing non-bilayer phospholipid arrangements NPA induced by some drugs like chloropromazine CPZ. The mice of this model produce anti-NPA IgG antibodies; these antibodies are mainly formed via germinal center GC. However, the cells that participate in a GC reaction against lipidic antigens are unknown; therefore, we study these cells in the mouse model of Lupus induced by NPA and compared them with a GC reaction against ovalbumin OVA, because the cells that participate in a GC reaction against protein antigens are well known. We studied germinal center B cells, plasma cells, dendritic cells, follicular dendritic cells FDC, T follicular helper cells TFH, T follicular regulatory cells TFR and macrophages from the groups administered with OVA or NPA and compared them with mice without administration. Then we extracted the spleen and the mesenteric lymph nodes and perform flow cytometry and H&E staining at days 5, 10, 15 and 30 postadministration. Histologically, germinal centers were found in both groups at day 5. The mice administered with NPA, present an increase of germinal center B cells 15 days post-administration and a bigger size of the secondary lymphoid organs, the mice administrated with OVA present an increase of these cells and bigger lymph organs at day 10. The higher percentage of plasma cells was found 30 days after the administration of OVA; while dendritic cells and TFH cells presented similar percentages in both groups at all times. For both antigens, the FDC increase at day 5 and 15, the macrophages from day 10 to 15 and the TFR cells increase at day 15.

Molecular selection and initial characterization of a new inducer and a new destabilizer of non-bilayer phospholipid arrangements

The mouse model of a lupus-like disease developed by our research group is unique, because it’s obtained by the stabilization of lipidic structures called non-bilayer phospholipid arrangements (NPAs), which induce the production of anti-NPA antibodies that trigger the disease in mice, which are in turn detected in patients with systemic lupus erythematosus. NPAs are produced when a lipid bilayer composed of conic and cylindric phospholipids, is modified by certain drugs (procainamide, chlorpromazine) or the manganese cation. Usually, drugs/substances are chosen to be tested as NPA inducers when they are known to trigger a lupus-like disease in humans. However, here we selected a group of molecules only by their structural similarity with the known inducers and the known destabilizer (chloroquine) and experimentally tested their effect on the formation or destabilization of NPAs in liposomes by flow cytometry. Firstly, we identified promethazine and procaine, similar to chlorpromazine and chloroquine, respectively. Promethazine acted as an inducer, with a broader range of concentrations of action in comparison with chlorpromazine, but it was more sensitive to the destabilizer. Procaine was found to be a weaker destabilizer than chloroquine, as it has an effect only at higher concentrations. This strategy showed that molecular characteristics could also be good predictors of their action on lipid bilayers and NPAs formation.

Analysis of immune cells from mice with Chagas disease treated with NPOx-B

Chagas disease is a parasitic disease caused by Trypanosoma cruzi it is endemic in Latin America, where is a major health problem since it affects 8–10 million people, causes 50,000 deaths per year and about 25% of the population is at risk of acquiring the disease. It remains practically incurable, mainly because of the limited interest in developing new drugs and because the drugs available for its treatment, Benznidazole (Bz) and Nifurtimox (Nx) are inefficient to cure patients. The acute phase of the disease appears shortly after infection, the chronic phase appears after a silent asymptomatic period that may last several years. During the chronic phase, the heart, esophagus, colon and PNS are irreversibly affected, patients usually die from heart failure. The chronic phase may be established by the evasion of the immune response by the parasite, secondly because Bz and Nx generate free radicals that can affect the cells of the immune system (CIS) which could favour the chronic phase. In our research group, we design and synthesized the benzyl ester of Npropyl oxamic (NPOxB) that is an effective inhibitor of the alpha-hydroxy acid dehydrogenase II enzyme, which is a specific enzyme in the glycolytic pathway of the parasite. In this work we treated with NPOxB or Bz infected mice with NINOA or INC5 strains, we evaluate the parasitaemia, the macrophages, B, T, plasma and dendritic cells. The NPOx-B decreased more the parasitaemia of both T. cruzi strains than the Bz. The mice infected and treated with Bz showed a decrease in B, T and plasma cells compared to the infected mice treated with NPOxB. So NPOxB is more effective in decrease the parasitaemia and lacks the toxicity of Bz, it doesn’t affect in CIS, the cure of the disease can be achieved more efficiently.

Development of a murine model resembling human lupus in mice parasitized with Trichinella spiralis

Deregulation of Th1 and Th17 immune responses is fundamental in the development of autoimmune diseases, like Systemic Lupus Erythematosus that is a chronic inflammatory autoimmune disease characterized by the production of autoantibodies that cause inflammation and damage to different organs. New therapeutic approaches for autoimmune diseases have been based on the fact that nematodes such as Trichinella spiralis decrease the inflammatory response by inducing the production of anti-inflammatory cytokines, which are potent modulators of T cell function. Recent studies have shown that the proteins secreted by T. spiralis, or the infection itself, induce a polarized Th2/Treg response and the production of regulatory cytokines, which are associated with the amelioration of autoimmune diseases such as colitis, respiratory tract inflammation, type 1 diabetes and experimental autoimmune encephalomyelitis. In this work, mice were infected and, after the life cycle was completed, a procedure to develop lupus was performed. The level of autoantibodies and antibodies anti-Trichinella were detected as well as the levels of Th1 and Th2 cytokines. Here, we show the relevance of studying the immune response in a murine model resembling the human lupus in the presence of T. spiralis muscular larvae, because it provides new information on the immunoregulation of lupus and reveals the effect on its progression.

Extracellular Vesicles Released from Mycobacterium tuberculosis-Infected Neutrophils Promote Macrophage Autophagy and Decrease Intracellular Mycobacterial Survival

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (Mtb). In the lungs, macrophages and neutrophils are the first immune cells that have contact with the infecting mycobacteria. Neutrophils are phagocytic cells that kill microorganisms through several mechanisms, which include the lytic enzymes and antimicrobial peptides that are found in their lysosomes, and the production of reactive oxygen species. Neutrophils also release extracellular vesicles (EVs) (100-1,000 nm in diameter) to the extracellular milieu; these EVs consist of a lipid bilayer surrounding a hydrophilic core and participate in intercellular communication. We previously demonstrated that human neutrophils infected in vitro with Mtb H37Rv release EVs (EV-TB), but the effect of these EVs on other cells relevant for the control of Mtb infection, such as macrophages, has not been completely analyzed. In this study, we characterized the EVs produced by non-stimulated human neutrophils (EV-NS), and the EVs produced by neutrophils stimulated with an activator (PMA), a peptide derived from bacterial proteins (fMLF) or Mtb, and observed that the four EVs differed in their size. Ligands for toll-like receptor (TLR) 2/6 were detected in EV-TB, and these EVs favored a modest increase in the expression of the co-stimulatory molecules CD80, a higher expression of CD86, and the production of higher amounts of TNF-α and IL-6, and of lower amounts of TGF-β, in autologous human macrophages, compared with the other EVs. EV-TB reduced the amount of intracellular Mtb in macrophages, and increased superoxide anion production in these cells. TLR2/6 ligation and superoxide anion production are known inducers of autophagy; accordingly, we found that EV-TB induced higher expression of the autophagy-related marker LC3-II in macrophages, and the co-localization of LC3-II with Mtb inside infected macrophages. The intracellular mycobacterial load increased when autophagy was inhibited with wortmannin in these cells. In conclusion, our results demonstrate that neutrophils produce different EVs in response to diverse activators, and that EV-TB activate macrophages and promote the clearance of intracellular Mtb through early superoxide anion production and autophagy induction, which is a novel role for neutrophil-derived EVs in the immune response to Mtb.

Anti-Lipid IgG Antibodies Are Produced via Germinal Centers in a Murine Model Resembling Human Lupus

Anti-lipid IgG antibodies are produced in some mycobacterial infections and in certain autoimmune diseases [such as anti-phospholipid syndrome, systemic lupus erythematosus (SLE)]. However, few studies have addressed the B cell responses underlying the production of these immunoglobulins. Anti-lipid IgG antibodies are consistently found in a murine model resembling human lupus induced by chlorpromazine-stabilized non-bilayer phospholipid arrangements (NPA). NPA are transitory lipid associations found in the membranes of most cells; when NPA are stabilized they can become immunogenic and induce specific IgG antibodies, which appear to be involved in the development of the mouse model of lupus. Of note, anti-NPA antibodies are also detected in patients with SLE and leprosy. We used this model of lupus to investigate in vivo the cellular mechanisms that lead to the production of anti-lipid, class-switched IgG antibodies. In this murine lupus model, we found plasma cells (Gr1⁻, CD19⁻, CD138⁺) producing NPA-specific IgGs in the draining lymph nodes, the spleen, and the bone marrow. We also found a significant number of germinal center B cells (IgD⁻, CD19⁺, PNA⁺) specific for NPA in the draining lymph nodes and the spleen, and we identified in situ the presence of NPA in these germinal centers. By contrast, very few NPA-specific, extrafollicular reaction B cells (B220⁺, Blimp1⁺) were found. Moreover, when assessing the anti-NPA IgG antibodies produced during the experimental protocol, we found that the affinity of these antibodies progressively increased over time. Altogether, our data indicate that, in this murine model resembling human lupus, B cells produce anti-NPA IgG antibodies mainly via germinal centers.

Participation of plasmacytoid dendritic cells and NKT cells in the mouse model of lupus induced by non-bilayer phospholipid arrangements

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease where animal models are used to study its pathogenesis. We have developed a mouse model of an autoimmune disease that resembles human lupus by the injection of liposomes bearing non-bilayer phospholipid arrangements (NPA). We detected the presence of IgG antibodies against NPA in the serum of mice with lupus and patients with SLE. In this work, we determined by citofluorometry the presence of plasmacytoid dendritic cells (pDC) the main producer of type I interferons, and of NKT cells in the secondary lymphoid organs of mice 30 and 60 days after the injection of liposomes with or without NPA induced with 8 mM promazine. In both groups of mice injected with liposomes bearing NPA a significant increase of pDC cells (5-fold) was found which correlates with the high concentration of type I interferon previously detected in this mouse model of lupus and in patients with SLE. A significant increase of NKT (3-fold) was detected at 30 days, specifically in the NKT subpopulation CD4+ that is known to cooperate with B cells in response of lipid antigens; this increase suggests its probable involvement in adaptive immune responses, which lead to the production of anti-NPA IgG antibodies. The increase of pDC and NKT cells found by cytometry in secondary lymphoid organs in this work, suggests their involvement in the formation of anti-NPA IgG antibodies and the development of the disease resembling human lupus.

Detection of anti-non bilayer phospholipids arragements antibodies and genotyping in patients with systemic lupus erythematosus and secondary antiphospholipid syndrome

Phospholipids are the main structural constituents of all cell membranes, their form the smooth bilayer matrix that delimited cells in which membrane proteins are located. However, some anionic phospholipids can lead to the formation of nonbilayer phospholipid arrangements (NPA) within the bilayer. NPA are transient but when they are stabilized by the drugs chlorpromazine, procainamide or hydralazine, which produced lupus-like disease in humans, they induce a disease resembling human lupus in mice. Mice present IgM and IgG antibodies against NPA which appear 4 weeks before that autoantibodies against cardiolipin, histones, nuclear and lupus anticoagulant antibodies. Mice also present histopathological abnormalities in the skin and kidneys similar to those observed in systemic lupus erythematosus (SLE). We proposed that the recognition of NPA by anti-NPA antibodies and after by the classical complement pathway causes cell lysis exposing intracellular antigens with the consequent formation of autoantibodies. Antibodies against NPA have been described in patients with SLE, lepromatous leprosy and hypertensive disorders of pregnancy. The present investigation is a clinical study not randomized, prospective, in Mexican mestizos patients of any sex and age, with SLE or with secondary antiphospholipid syndrome in which we found that the elevated levels of anti-NPA antibodies could trigger autoimmunity in these diseases and we determined that high titers lead to increased activity and correlate with the expression of HLA-DR, HLA-DQ, HLA-A, HLA-B, IL-10 (-1082G/A, -819C/T, -592C/A) and PTPN22 (+1858C/T) alleles. All clinic assays were approved by the Committee of Bioethics of our Institutions.

Trypanocidal effect of the benzyl ester of N-propyl oxamate: a bi-potential prodrug for the treatment of experimental Chagas disease

BACKGROUND

Chagas disease, which is caused by Trypanosoma cruzi, is a major health problem in Latin America, and there are currently no drugs for the effective treatment of this disease. The energy metabolism of T. cruzi is an attractive target for drug design, and we previously reported that inhibitors of α-hydroxy acid dehydrogenase (HADH)-isozyme II exhibit trypanocidal activity. N-Propyl oxamate (NPOx) is an inhibitor of HADH-isozyme II, and its non-polar ethyl ester (Et-NPOx) is cytotoxic to T. cruzi. A new derivative of NPOx has been developed in this study with higher trypanocidal activity, which could be used for the treatment of Chagas disease.

METHODS

The benzyl ester of NPOx (B-NPOx) was synthesized and its activity evaluated towards epimastigotes and bloodstream trypomastigotes (in vitro), as well as mice infected with T. cruzi (in vivo). The activity of B-NPOx was also compared with those of Et-NPOx, benznidazole (Bz) and nifurtimox (Nx). NINOA, Miguz, Compostela, Nayarit and INC-5 T. cruzi strains were used in this study.

RESULTS

Polar NPOx did not penetrate the parasites and exhibited no trypanocidal activity. In contrast, the hydrophobic ester B-NPOx exhibited trypanocidal activity in vitro and in vivo. B-NPOx exhibited higher trypanocidal activity than Et-NPOx, Bz and Nx towards all five of the T. cruzi strains. The increased activity of B-NPOx was attributed to its hydrolysis inside the parasites to give NPOx and benzyl alcohol, which is an antimicrobial compound with trypanocidal effects. B-NPOx was also effective against two strains of T. cruzi that are resistant to Bz and Nx.

CONCLUSION

B-NPOx exhibited higher in vitro (2- to 14.8-fold) and in vivo (2.2- to 4.5-fold) trypanocidal activity towards T. cruzi than Et-NPOx. B-NPOx also exhibited higher in vitro (2- to 24-fold) and in vivo (1.9- to 15-fold) trypanocidal activity than Bz and Nx. B-NPOx is more lipophilic than Et-NPOx, allowing for better penetration into T. cruzi parasites, where the enzymatic cleavage of B-NPOx would give NPOx and benzyl alcohol, which are potent trypanocidal agents. Taken together with its low toxicity, these results suggest that B-NPOx could be used as a potent prodrug for the treatment of Chagas disease.

Hypocholesterolemic and choleretic effects of three dimethoxycinnamic acids in relation to 2,4,5-trimethoxycinnamic acid in rats fed with a high-cholesterol/cholate diet

BACKGROUND

2,4,5-Trimethoxycinnamic acid (2,4,5-TMC) is the major and non-toxic metabolite of α-asarone, which retains hypocholesterolemic and choleretic activities. We compared the activities of 2,4,5-TMC with those of 2,4-dimethoxycinnamic acid (2,4-DMC), 3,4-DMC and 3,5-DMC, to understand the role of the methoxyls on carbons 2, 4 and 5 on the pharmacologic properties of these compounds.

METHODS

The methoxycinnamic acids were administered to high-cholesterol/cholate-fed rats. We measured bile flow, and quantified bile acids, phospholipids and cholesterol in bile, and cholesterol and cholesterol-lipoproteins in serum. The inhibition of HMG-CoA reductase by the methoxycinnamic acids was evaluated in vitro.

RESULTS

The four methoxycinnamic acids decreased serum cholesterol, without affecting the concentration of HDL-cholesterol. 2,4,5-TMC produced the highest decrease in LDL-cholesterol, 73.5%, which exceeds the range of statins (20-40%), and produced the highest inhibition of the activity of HMG-CoA reductase. 3,4-DMC produced the highest increase in bile flow, bile acids and phospholipids concentrations, and reduction in bile cholesterol, which led to a decrease in the biliary cholesterol saturation index.

CONCLUSIONS

2,4,5-TMC (which has three methoxyls) had the highest hypocholesterolemic activity, while 3,4-DMC, which lacks the methoxyl in carbon 2 but conserves the two other methoxyls in an adjacent position, had the highest choleretic activity and a probable cholelitholytic activity. In methoxycinnamic acids with two methoxyls in non-adjacent positions (2,4-DMC and 3,5-DMC), the hypocholesterolemic and choleretic activities were not as evident. 2,4,5-TMC and 3,4-DMC, which did not cause liver damage during the treatment period, should be further explored as a hypocholesterolemic and choleretic compounds in humans.

Molecular organization of the non-bilayer phospholipid arrangements that induce an autoimmune disease resembling human lupus in mice

Non-bilayer phospholipid arrangements are three-dimensional structures that can form when anionic phospholipids with an intermediate form of the tubular hexagonal phase II (H(II)), such as phosphatidic acid, phosphatidylserine or cardiolipin, are present in a bilayer of lipids. The drugs chlorpromazine and procainamide, which trigger a lupus-like disease in humans, can induce the formation of non-bilayer phospholipid arrangements, and we have previously shown that liposomes with non-bilayer arrangements induced by these drugs cause an autoimmune disease resembling human lupus in mice. Here we show that liposomes with non-bilayer phospholipid arrangements induced by Mn²⁺ cause a similar disease in mice. We extensively characterize the physical properties and immunological reactivity of liposomes made of the zwitterionic lipid phosphatidylcholine and a H(II)-preferring lipid, in the absence or presence of Mn²⁺, chlorpromazine or procainamide. We use an hapten inhibition assay to define the epitope recognized by sera of mice with the disease, and by a monoclonal antibody that binds specifically to non-bilayer phospholipid arrangements, and we report that phosphorylcholine and glycerolphosphorylcholine, which form part of the polar region of phosphatidylcholine, are the only haptens that block the binding of the tested antibodies to non-bilayer arrangements. We propose a model in which the negatively charged H(II)-preferring lipids form an inverted micelle by electrostatic interactions with the positive charge of Mn²⁺, chlorpromazine or procainamide; the inverted micelle is inserted into the bilayer of phosphatidylcholine, whose polar regions are exposed and become targets for antibody production. This model may be relevant in the pathogenesis of human lupus.

Chlorpromazine, procainamide and hydralazine produced a murine autoimmune disease resembling human lupus (48.31)

Chlorpromazine, procainamide and hydralazine have indeed been implicated in producing a human lupus-like disorder. These drugs induce the formation of a phospholipid arrangement different to the lipid bilayer called non-bilayer phospholipid arrangement (NPA). Since these drugs form NPA in liposomes and cultured cells, it is possible that these drugs can stabilize NPA structures in cell membranes producing an abnormal NPA exposure, perhaps facilitating the subsequent production of specific antibodies. To evaluate this potential role of NPA inductors, the drugs alone or drug-induced NPA were administered to BALB/c mice. We observed that 30-45% of mice treated with NPA inductors and 55-60% treated with drug-induced NPA, produced anti-NPA antibodies. These antibodies appeared 4 weeks prior to anti-cardiolipin, anticoagulant, anti-histone and anti-nuclear antibodies. Mice presented some areas of the face with alopecia, the histopathology of these areas showed similar changes to those found in human lupus skin lesions. Dense inflammatory infiltrate in dermis with deposition of immune complexes in dermal-epidermal junction and also along the basement membrane of glomerular capillaries were observed. This model of lupus might contribute to a better understanding of the immunological basis of human lupus and probably toward the development of better human therapeutic strategies.