The inhibitory effect of cromolyn sodium and ketotifen on Toxoplasma gondii entrance into host cells in vitro and in vivo

Evaluating the Effect of Cinnarizine on Promastigotes and Amastigotes forms of Leishmania major

As an important global disease, cutaneous leishmaniasis is associated with complications such as secondary infections and atrophic scars. The first line treatment with antimonials is expensive and reported to have serious side effects and enhance resistance development. The main objective of this study was to evaluate the effect of Cinnarizine on standard strains of Leishmania major because of paucity of information on this subject.

METHODS

In this experimental study, four concentrations of the drug (5, 10, 15 and 20 μg/ml) were added to Leishmania major cultures at 24, 48 and 72 hours intervals. MTT assays were performed to determine parasite viability and drug toxicity. Leishmania major promastigotes were augmented to the in vitro cultured macrophages (J774 cells) and then incubated for 72 hours. Half maximal inhibitory concentration (IC50) was ascertained by counting parasites. The inhibitory effect of the drug was compared with that of Glucantime. Flow-cytometry was performed to investigate apoptosis. Each test was repeated thrice.

RESULTS

The IC50 values of Cinnarizine after 72 hours were calculated to be 34.76 μg/ml and 23.73 μg/ml for promastigotes and amastigotes, respectively. The results of MTT assays showed 48 % promastigote viability after 72 hour-exposure to Cinnarizine at 20 μg/ml concentration. Programmed cell death in promastigote- and amastigote-infected macrophages was quantified to be 13.66 % and 98.7 %, respectively. Flow- cytometry analysis indicated that Cinnarizine induced early and late apoptosis in parasites. All treatments produced results which differed significantly from control group (P<0.05).

CONCLUSION

Cinnarizine showed low toxicity with anti-leishmanial and apoptosis effects on both promastigote and intracellular amastigote forms. Therefore, we may suggest further assessment on animal models of this drug as candidates for cutaneous leishmaniasis therapy.

Identification of a novel potassium channel (GiK) as a potential drug target in Giardia lamblia: Computational descriptions of binding sites

Background

The protozoan Giardia lamblia is the causal agent of giardiasis, one of the main diarrheal infections worldwide. Drug resistance to common antigiardial agents and incidence of treatment failures have increased in recent years. Therefore, the search for new molecular targets for drugs against Giardia infection is essential. In protozoa, ionic channels have roles in their life cycle, growth, and stress response. Thus, they are promising targets for drug design. The strategy of ligand-protein docking has demonstrated a great potential in the discovery of new targets and structure-based drug design studies.

Methods

In this work, we identify and characterize a new potassium channel, GiK, in the genome of Giardia lamblia. Characterization was performed in silico. Because its crystallographic structure remains unresolved, homology modeling was used to construct the three-dimensional model for the pore domain of GiK. The docking virtual screening approach was employed to determine whether GiK is a good target for potassium channel blockers.

Results

The GiK sequence showed 24–50% identity and 50–90% positivity with 21 different types of potassium channels. The quality assessment and validation parameters indicated the reliability of the modeled structure of GiK. We identified 110 potassium channel blockers exhibiting high affinity toward GiK. A total of 39 of these drugs bind in three specific regions.

Discussion

The GiK pore signature sequence is related to the small conductance calcium-activated potassium channels (SKCa). The predicted binding of 110 potassium blockers to GiK makes this protein an attractive target for biological testing to evaluate its role in the life cycle of Giardia lamblia and potential candidate for the design of novel antigiardial drugs.

A systematic review of Toxoplasma gondii antigens to find the best vaccine candidates for immunization

At present, there is not any available accepted vaccine for prevention of Toxoplasma gondii (T. gondii) in human and animals. We conducted literature search through English (Google Scholar, PubMed, Science Direct, Scopus, EBSCO, ISI Web of Science) scientific paper databases to find the best vaccine candidates against toxoplasmosis among T. gondii antigens. Articles with information on infective stage, pathogenicity, immunogenicity and characterization of antigens were selected. We considered that the ideal and significant vaccines should include different antigens and been expressed in all infective stages of the parasite with a high pathogenicity and immunogenicity. Evaluation within this systematic review indicates that MIC 3, 4, 13, ROP 2, RON 5, GRA 1, 6, 8, 14 are expressed in all three infective stages and have pathogenicity and immunogenicity. MIC 5, ROM 4, GRA 2, 4, 15, ROP 5, 16, 17, 38, RON 4, MIC 1, GRA 10, 12, 16, SAG 3 are expressed in only tachyzoites and bradyzoites stages of T. gondii with pathogenicity/immunogenicity. Some antigens appeared to be expressed in a single stage (tachyzoites) but have high pathogenicity and induce immune response. They include enolase2 (ENO2), SAG 1, SAG5D, HSP 70, ROM 1, ROM 5, AMA 1, ROP 18, RON2 and GRA 24. In conclusion, current vaccination against T. gondii infection is not satisfactory, and with the increasing number of high-risk individuals, the development of an effective and safe specific vaccine is greatly valuable for toxoplasmosis prevention. This systematic review reveals prepare candidates for immunization studies.

Ketotifen fumarate attenuates feline gingivitis related with gingival microenvironment modulation

Gingivitis is evidenced by inflammation of the free gingiva, and still reversible. If left untreated, it may then progress to periodontitis. In the present study, the therapeutical effect of ketotifen fumarate on gingivitis was explored. Domestic cats with varying degrees of gingivitis naturally were enrolled in this study. Subgroups of animals were treated twice daily for one week with or without ketotifen fumarate (5 mg/kg). Effects of ketotifen fumarate were measured on gingival index, cells accumulation, mediators release, receptor-ligand interaction, oxidative stress, MAPK and NF-κB pathways, epithelial barrier and apoptosis. Ketotifen fumarate attenuated the initiation and progression of gingivitis, inhibited the infiltrations of mast cells, B lymphocytes, T lymphocytes, macrophages, neutrophils and eosinophils as well as the release of IgE, β-hexosaminidase, tryptase, chymase, TNF-α, IL-4, and IL-13, influenced endothelial cells, fibroblasts and epithelial cells proliferation and apoptosis, and induced Th2 cells polarization, where ketotifen fumarate also might affect their interactions. Ketotifen fumarate reduced the oxidative stress, and inhibited NF-κB and p38 MAPK related with mast cells and macrophages accumulation. Ketotifen fumarate improved the aberrant expression of ZO-1 and inhibits the following apoptosis. On the other hand, these cells and mediators augmented functional attributes of them involving SCF/c-Kit, α4β7/VCAM-1 and IL-8/IL-8RB interactions, thus creating a positive feedback loop to perpetuate gingivitis, where an inflammation microenvironment was modeled. Our results showed a previously unexplored therapeutic potential of ketotifen fumarate for gingivitis and further suggest that, in addition to biofilms, targeting inflammation microenvironment could be new strategy for the treatment of gingivitis/periodontitis.

Survey on synergism effect of ketotifen in combination with pyrimethamine in treatment of acute murine toxoplasmosis

Background

Standard treatment of toxoplasmosis is accompanied by severe side effects and low tolerability; accordingly, alternative medicines are critically needed. Ketotifen (KET) as a cell membrane stabilizer could be an appropriate inhibitor of Toxoplasma gondii (T. gondii) parasite entrance into the host cells. Therefore, the focus of current study is characterization of the anti-Toxoplasma activity of KET in the acute phase of toxoplasmosis in murine model as pre-treatment and post-treatment (before and after infection with RH strain). KET was used intraperitoneally both individually (2 and 3 mg/kg/day) and in combination with pyrimethamine (PYR) (50 mg/kg/day). One week after the post infection, DNA was extracted from brain biopsies samples. Parasite load was calculated using Quantitative-PCR (Q-PCR) in a triplicate reaction for each DNA with the target for at RE (a 529 bp repeat element) gene.

Results

A significant difference between KET and control groups was observed (P < 0.001) in the pre-treatment and post-treatment groups. Both KET and the combination of KET and PYR showed a reduction in the parasite load in brain through the acute phase of the infection. 2 mg/kg/day dose of KET resulted in higher anti-Toxoplasma activity (15,698 parasites/ml) compared to 3 mg/kg/day dose of KET (72,898 parasites/ml) in brain in the pre-treatment group. In addition, KET combined with PYR significantly decreased the parasite load in the post-treatment group.

Conclusions

Our results indicated that KET has both prophylactic and therapeutic effects on acute phases of the disease.

A Systematic Review of In vitro and In vivo Activities of Anti-Toxoplasma Drugs and Compounds (2006-2016)

The currently available anti-Toxoplasma agents have serious limitations. This systematic review was performed to evaluate drugs and new compounds used for the treatment of toxoplasmosis. Data was systematically collected from published papers on the efficacy of drugs/compounds used against Toxoplasma gondii (T. gondii) globally during 2006-2016. The searched databases were PubMed, Google Scholar, Science Direct, ISI Web of Science, EBSCO, and Scopus. One hundred and eighteen papers were eligible for inclusion in this systematic review, which were both in vitro and in vivo studies. Within this review, 80 clinically available drugs and a large number of new compounds with more than 39 mechanisms of action were evaluated. Interestingly, many of the drugs/compounds evaluated against T. gondii act on the apicoplast. Therefore, the apicoplast represents as a potential drug target for new chemotherapy. Based on the current findings, 49 drugs/compounds demonstrated in vitro half-maximal inhibitory concentration (IC50) values of below 1 μM, but most of them were not evaluated further for in vivo effectiveness. However, the derivatives of the ciprofloxacin, endochin-like quinolones and 1-[4-(4-nitrophenoxy) phenyl] propane-1-one (NPPP) were significantly active against T. gondii tachyzoites both in vitro and in vivo. Thus, these compounds are promising candidates for future studies. Also, compound 32 (T. gondii calcium-dependent protein kinase 1 inhibitor), endochin-like quinolones, miltefosine, rolipram abolish, and guanabenz can be repurposed into an effective anti-parasitic with a unique ability to reduce brain tissue cysts (88.7, 88, 78, 74, and 69%, respectively). Additionally, no promising drugs are available for congenital toxoplasmosis. In conclusion, as current chemotherapy against toxoplasmosis is still not satisfactory, development of well-tolerated and safe specific immunoprophylaxis in relaxing the need of dependence on chemotherapeutics is a highly valuable goal for global disease control. However, with the increasing number of high-risk individuals, and absence of a proper vaccine, continued efforts are necessary for the development of novel treatment options against T. gondii. Some of the novel compounds reviewed here may represent good starting points for the discovery of effective new drugs. In further, bioinformatic and in silico studies are needed in order to identify new potential toxoplasmicidal drugs.

Evaluation of Propranolol Effect on Experimental Acute and Chronic Toxoplasmosis Using Quantitative PCR

Current therapies against toxoplasmosis are limited, and drugs have significant side effects and low efficacies. We evaluated the potential anti-Toxoplasma activity of propranolol at a dose of 2 or 3 mg/kg of body weight/day in vivo in the acute and chronic phases. Propranolol as a cell membrane-stabilizing agent is a suitable drug for inhibiting the entrance of Toxoplasma gondii tachyzoites into cells. The acute-phase assay was performed using propranolol, pyrimethamine, and propranolol plus pyrimethamine before (pretreatment) and after (posttreatment) intraperitoneal challenge with 1 × 10³ tachyzoites of the virulent T. gondii strain RH in BALB/c mice. Also, in the chronic phase, treatment was performed 12 h before intraperitoneal challenge with 1 × 10⁶ tachyzoites of the virulent strain RH of T. gondii in rats. One week (in the acute phase) and 2 months (in the chronic phase) after postinfection, tissues were isolated and DNA was extracted. Subsequently, parasite load was calculated using quantitative PCR (qPCR). In the acute phase, in both groups, significant anti-Toxoplasma activity was observed using propranolol (P < 0.001). Propranolol in the pretreatment group showed higher anti-Toxoplasma activity than propranolol in posttreatment in brain tissues, displaying therapeutic efficiency on toxoplasmosis. Also, propranolol combined with pyrimethamine reduced the parasite load as well as significantly increased survival of mice in the pretreatment group. In the chronic phase, anti-Toxoplasma activity and decreased parasite load in tissues were observed with propranolol. In conclusion, the presented results demonstrate that propranolol, as an orally available drug, is effective at low doses against acute and latent murine toxoplasmosis, and the efficiency of the drug is increased when it is used in combination therapy with pyrimethamine.