Investigation of caspase-1 activity and interleukin-1β production in murine macrophage cell lines infected with Leishmania major

The non-pathogenic protozoon Leishmania tarentolae interferes with the activation of NLRP3 inflammasome in human cells: new perspectives in the control of inflammation

Background

Innate immune responses against infectious agents can act as triggers of inflammatory diseases. On the other hand, various pathogens have developed mechanisms for the evasion of the immune response, based on an inhibition of innate immunity and inflammatory responses. Inflammatory diseases could thus be controlled through the administration of pathogens or pathogen-derived molecules, capable of interfering with the mechanisms at the basis of inflammation. In this framework, the NLRP3 inflammasome is an important component in innate antimicrobial responses and a major player in the inflammatory disease. Parasites of the genus Leishmania are master manipulators of innate immune mechanisms, and different species have been shown to inhibit inflammasome formation. However, the exploitation of pathogenic Leishmania species as blockers of NLRP3-based inflammatory diseases poses safety concerns.

Methods

To circumvent safety issues associated with pathogenic parasites, we focused on Leishmania tarentolae, a species of Leishmania that is not infectious to humans. Because NLRP3 typically develops in macrophages, in response to the detection and engulfment microorganisms, we performed our experiments on a monocyte-macrophage cell line (THP-1), either wild type or knockout for ASC, a key component of NLRP3 formation, with determination of cytokines and other markers of inflammation.

Results

L. tarentolae was shown to possess the capability of dampening the formation of NLRP3 inflammasome and the consequent expression of pro-inflammatory molecules, with minor differences compared to effects of pathogenic Leishmania species.

Conclusion

The non-pathogenic L. tarentolae appears a promising pro-biotic microbe with anti-inflammatory properties or a source of immune modulating cellular fractions or molecules, capable of interfering with the formation of the NLRP3 inflammasome.

Investigation of Antiparasitic Effects of Eisenia fetida Extract (Annelida, Lumbricidae) Against Toxoplasma gondii: In Vitro Study

Background:

Toxoplasmosis which is caused by Toxoplasma gondii, is a widespread parasitic disease that affects approximately one-third of the world's population. Due to the significant side effects of anti-Toxoplasma drugs, it is necessary to acquire new drugs with low toxicity, high activity, cheaper and more effective.

Objective:

Earthworm has long been used as a therapeutic source of medicine in China and other parts of the Far East. Therefore, the purpose of the present study was to investigate of antiparasitic effects of Eisenia fetida extract against T. gondii in the Vero cell line.

Materials and Methods:

The effects of the extract on the parasite, Vero cell, and the parasitized cells were estimated by MTT assay in vitro. Apoptosis was also measured by flow cytometer in three groups of extract-treated parasites, extract-treated Vero cells, and extract-treated parasitic Vero cells, respectively.

Results:

The inhibitory effect of E. fetida extract and sulfadiazine was more than 85% and 65% on the parasite, respectively. Intracellular multiplication of the parasite in Vero cells during the 3 hours test showed a significant decrease compared to the 1 hour test (p<0.05). Flow cytometric analysis showed that with increasing concentration of E. fetida, apoptosis increased significantly (p<0.05).

Conclusion:

The results showed that E. fetida extract in vitro could have a significant antiparasitic effect against T. gondii.

Epidemiological Study of Parasitic Infections in BuMusa Island, Hormozgan

Background:

This epidemiological study aimed to investigate the prevalence of parasitic infections in BuMusa Island, Iran, in one year from 2015 to 2016.

Methods:

The current cross-sectional study was conducted in coordination with the health authorities of BuMusa on 732 intestinal samples and 1207 blood samples randomly collected from the island residents. Cutaneous lesions of 1207 people were clinically examined and those suspected of parasitic infections were enrolled. Also, 165 intestinal samples from domestic animals, 35 samples from water tanks, and 330 soil samples were taken to the laboratory to be investigated in terms of parasitic infections.

Results:

The obtained results showed 26.4% and 45.5% intestinal parasitic infections in humans and animals, respectively. The most prevalent infections in humans were Blastocystis hominis (8.6%), followed by Giardia lamblia (8.2%), and Entamoeba coli (6.8%); and the least prevalent infection was Enterobius vermicularis (<0.2%). Malaria agents and Leishmania were not observed in blood samples. Investigation of animal feces showed that the highest parasitic infection was Eimeria arloingi (16.4%), while the lowest prevalence belonged to Monizia expansa (0.6%). Hymenolepis nana eggs and Cyclops were detected in one sub-source of water tanks. Rhabditis larva, a free-living nematode, was observed in a soil sample.

Conclusion:

The prevalence of parasitic infections in BuMusa Island was relatively low probably due to its hot and dry climate.

The immunopathobiology of T cells in stress condition: a review

Several factors impact the immune responses such as the chemical nature of antigens, the physiologic and metabolic condition of the responsive cells, the site of antigen recognition, and neuroendocrine and pharmacological received agents. Incompatibility of host immune responses to the entrapped antigens leads to an immune pathological manner instead of an immune protection which results in the disharmony of the immune effective factors. Besides the fact that stress is one of the most common effective factors in human life, it also contributed to the protection, suppression, and pathology of the immune system. In this review article, the direct and indirect effects of the stress on the function of T cells and the contributed mechanism of action will be discussed.

Chemiluminescent microparticle immunoassay-based detection and prevalence of Toxoplasma gondii infection in childbearing women (Iran)

Toxoplasmosis is a common zoonotic disease, which is of particular importance in women before and during pregnancy. In this study, the chemiluminescent microparticle immunoassay was used to detect Toxoplasma gondii and the seroepidemiology of Toxoplasma gondii was investigated among childbearing women in Qom, Iran. In this study, 202 blood samples were collected from childbearing women for evaluation of toxoplasmosis. Serum samples were isolated to determine anti-Toxoplasma IgM and IgG antibodies. Based on findings, the total prevalence of anti-Toxoplasma antibodies was 134 (66.3%) [95% CI 59.6-72.5]. In addition, 133 (65.8%) [95% CI 59.1-72.1], 19 (9.4%) [95% CI 6.1-14.2] and 18 (8.9%) [95% CI 5.7-13.6] samples were IgG-positive, IgM-positive and positive for both antibodies, respectively. The highest infection rate was reported over the age of 35 years, and positive lgM antibodies were detected in women below 29 years. T. gondii infection showed a significant correlation with age, pregnancy, contact with cats, exposure to soil, and consumption of raw food (P < 0.05). The serological tests revealed that nearly 33.7% [95% CI 27.5-40.4] of women at childbearing age (49.1% [95% CI 36.4-61.9] of pregnant women versus 27.9% [95% CI 21.3-35.6] of non-pregnant women) had no anti-Toxoplasma antibodies. Therefore, this population is more prone to acute infections with Toxoplasma.

Transcriptional analysis of THP-1 cells infected with Leishmania infantum indicates no activation of the inflammasome platform

Leishmaniasis is caused by intracellular parasites transmitted to vertebrates by sandfly bites. Clinical manifestations include cutaneous, mucosal or visceral involvement depending upon the host immune response and the parasite species. To assure their survival inside macrophages, these parasites developed a plethora of highly successful strategies to manipulate various immune system pathways. Considering that inflammasome activation is critical for the establishment of a protective immune response in many parasite infections, in this study we determined the transcriptome of THP-1 cells after infection with L. infantum, with a particular focus on the inflammasome components. To this end, the human cell line THP-1, previously differentiated into macrophages by PMA treatment, was infected with L. infantum promastigotes. Differentiated THP-1 cells were also stimulated with LPS to be used as a comparative parameter. The gene expression signature was determined 8 hours after by RNA-seq technique. Infected or uninfected THP-1 cells were stimulated with nigericin (NIG) to measure active caspase-1 and TNF-α, IL-6 and IL-1β levels in culture supernatants after 8, 24 and 48 hours. L. infantum triggered a gene expression pattern more similar to non-infected THP-1 cells and very distinct from LPS-stimulated cells. Some of the most up-regulated genes in L. infantum-infected cells were CDC20, CSF1, RPS6KA1, CD36, DUSP2, DUSP5, DUSP7 and TNFAIP3. Some up-regulated GO terms in infected cells included cell coagulation, regulation of MAPK cascade, response to peptide hormone stimulus, negative regulation of transcription from RNA polymerase II promoter and nerve growth factor receptor signaling pathway. Infection was not able to induce the expression of genes associated with the inflammasome signaling pathway. This finding was confirmed by the absence of caspase-1 activation and IL-1β production after 8, 24 and 48 hours of infection. Our results indicate that L. infantum was unable to activate the inflammasomes during the initial interaction with THP-1 cells.

Visceral leishmaniasis, caused by Leishmania infantum, is a disease that affects millions of people worldwide. The entry of microorganisms into the host is commonly associated with activation of a multiprotein platform called inflammasome whose assembly culminates in caspase-1 activation and IL-1β production. ILβ activates other cells and effector mechanisms leading to clearance of pathogens. However, the involvement of inflammasomes in the human infection with L. infantum is poorly known. To investigate the parasite-host interaction is fundamental to understand the immunopathogenesis of visceral leishmaniasis and to allow the development of new therapeutic strategies. In this study, we used RNA-seq, a tool that allowed to investigate the global gene expression of THP-1 cells, which is a macrophage-like human cell line, infected with L. infantum. By using computational analysis, this approach allowed us to evaluate the expression of genes that compose the inflammasomes pathway and other gene networks and signaling pathways triggered after infection. This analysis indicated that, unlike species causing cutaneous leishmaniasis, L. infantum did not induce the expression of genes of inflammasome pathways, nor caspase-1 activation or IL-1β production, possibly reflecting a parasite strategy to manipulate immune system and therefore, to allow its survival inside the cells.

Leishmania Lipophosphoglycan Triggers Caspase-11 and the Non-canonical Activation of the NLRP3 Inflammasome

Activation of the NLRP3 inflammasome by Leishmania parasites is critical for the outcome of leishmaniasis, a disease that affects millions of people worldwide. We investigate the mechanisms involved in NLRP3 activation and demonstrate that caspase-11 (CASP11) is activated in response to infection by Leishmania species and triggers the non-canonical activation of NLRP3. This process accounts for host resistance to infection in macrophages and in vivo. We identify the parasite membrane glycoconjugate lipophosphoglycan (LPG) as the molecule involved in CASP11 activation. Cytosolic delivery of LPG in macrophages triggers CASP11 activation, and infections performed with Lpg1-/- parasites reduce CASP11/NLRP3 activation. Unlike bacterial LPS, purified LPG does not activate mouse CASP11 (or human Casp4) in vitro, suggesting the participation of additional molecules for LPG-mediated CASP11 activation. Our data identify a parasite molecule involved in CASP11 activation, thereby establishing the mechanisms underlying inflammasome activation in response to Leishmania species.

Engineering and introduction of de novo disulphide bridges in organophosphorus hydrolase enzyme for thermostability improvement

The organophosphorus hydrolase (OPH) has been used to degrade organophosphorus chemicals, as one of the most frequently used decontamination methods. Under chemical and thermal denaturing conditions, the enzyme has been shown to unfold. To utilize this enzyme in various applications, the thermal stability is of importance. The engineering of de novo disulphide bridges has been explored as a means to increase the thermal stability of enzymes in the rational method of protein engineering. In this study, Disulphide by Design software, homology modelling and molecular dynamics simulations were used to select appropriate amino acid pairs for the introduction of disulphide bridge to improve protein thermostability. The thermostability of the wild-type and three selected mutant enzymes were evaluated by half-life, delta G inactivation (ΔGi) and structural studies (fluorescence and far-UV CD analysis). Data analysis showed that half-life of A204C/T234C and T128C/E153C mutants were increased up to 4 and 24 min, respectively; however, for the G74C/A78C mutant, the half-life was decreased up to 9 min. For the T128C/E124C mutant, both thermal stability and Catalytic efficiency (kcat) were also increased. The half-life and ΔGi results were correlated to the obtained information from structural studies by circular dichroism (CD) spectrometry and extrinsic fluorescence experiments; as rigidity increased in A204C/T2234C and T128C/E153C mutants, half-life and ΔGi also increased. For G74C/A78C mutant, these parameters decreased due to its higher flexibility. The results were submitted a strong evidence for the possibility to improve the thermostability of OPH enzyme by introducing a disulphide bridge after bioinformatics design, even though this design would not be always successful.