Decrease In Parasite Burden Research Articles

Preparation and characterization of paromomycin encapsulated in lecithin-chitosan nanoparticles for the topical treatment of cutaneous leishmaniasis

Introduction: Leishmaniasis is a disease caused by the Leishmania protozoa, with Cutaneous Leishmaniasis (CL) being the most common form of the illness. Paromomycin (PM) has recently garnered increased interest for its effectiveness against Leishmania, but it is hindered by limited efficacy, low oral bioavailability, and rapid clearance. As far as we know, there have been no studies examining the impact of nano lecithin-chitosan-containing paromomycin (Nano-PM) on CL. Therefore, the objective of the present study was to create Nano-PM and assess its effects on the promastigotes in vitro and on the lesions caused by Leishmania major in the BALB/c mice model in vivo. Methods: The loading of PM into lecithin-chitosan nanoparticles was achieved using the ionic gelation method, and the resulting nanoparticles were characterized. The IC50 values for PM, Glucantim, and Nano-PM against promastigotes were determined after 24, 48, and 72 hours of treatment. The viability of promastigotes was assessed using the MTT assay. The Nano-PM formulation was administered intramuscularly to mice for a period of 28 days, during which lesion sizes were measured weekly. Furthermore, the parasite load in the infected mice was quantified using quantitative realtime polymerase chain reaction (qPCR). Results: IC50 of Nano-PM was significantly lower than Glucantim (p < 0.0001 after24 h incubation, p = 0.013 for 48h and p < 0.0001 for 72 h) and PM (p < 0.0001 after24 h, p = 0.003 for 48h and p < 0.0001 for 72h). All concentrations of Nano-PM had the highest toxicity on promastigotes in comparison with other groups after 24, 48, and 72 h treatment. Moreover, a significant reduction in the lesion size was found in the Nano-PM group in comparison with the control group after three (p = 0.0369) and four (p = 0.0009) weeks of treatment. More importantly, Nano-PM significantly reduced the parasite load compared to the control and the lecithin-chitosan groups (p = 0.001 for both). Conclusion: Our findings showed that Nano-PM had lower toxicity (lower IC50) on promastigotes compared to Glucantim and PM. Moreover, Nano-PM treated mice showed reduced lesion size compared to the control group. Additionally, Nano-PM led to a significant decrease in parasite burden compared to the control group and the lecithin-chitosan group. Nevertheless, more complementary research is needed to approve our findings.

Biostimulated-sesame sprout extracts as potential agents against Leishmania mexicana.

Leishmania mexicana is one of the causal agents of cutaneous leishmaniasis. Current antileishmanial chemotherapeutics have demonstrated adverse side effects; thus, alternative treatments are needed. In this study, we performed in silico and in vitro analyses of the leishmanicidal potential of the most abundant phenolic compounds identified in black sesame sprouts biostimulated with Bacillus clausii. The molecular docking analysis showed strong interactions (binding free energies between -6.5 and -9.5 kcal/mol) of sesaminol 2-O-triglucoside, pinoresinol dihexoside, isoverbascoside, and apigenin with the arginase, leishmanolysin, cysteine peptidase B, and pyruvate kinase leishmanial enzymes. Furthermore, almost all phenolic compounds interacted with the active site residues of L. mexicana enzymes. In vitro, the B. clausii-biostimulated sprout phenolic extracts and apigenin inhibited the growth of promastigotes with IC50 values of 0.08 mg gallic acid equivalent/mL and 6.42 μM (0.0017 mg/mL), respectively. Additionally, in the macrophage infection model, cells treated with B. clausii-biostimulated sprout phenolic extracts and infected with L. mexicana exhibited significantly (P<0.05) reduced nitric oxide production and decreased parasite burden. Altogether, our study provides important data related to high efficacy and less toxic natural antileishmanial candidates against promastigotes of L. mexicana.

A conserved protein of Babesia microti elicits partial protection against Babesia and Plasmodium infection

BackgroundThe protozoan parasite Babesia microti that causes the zoonotic disease babesiosis resides in the erythrocytes of its mammalian host during its life-cycle. No effective vaccines are currently available to prevent Babesia microti infections.MethodsWe previously identified a highly seroactive antigen, named Bm8, as a B. microti conserved erythrocyte membrane-associated antigen, by high-throughput protein chip screening. Bioinformatic and phylogenetic analysis showed that this membrane-associated protein is conserved among apicomplexan hemoprotozoa, such as members of genera Babesia, Plasmodium and Theileria. We obtained the recombinant protein Bm8 (rBm8) by prokaryotic expression and purification.ResultsImmunofluorescence assays confirmed that Bm8 and its Plasmodium homolog were principally localized in the cytoplasm of the parasite. rBm8 protein was specifically recognized by the sera of mice infected with B. microti or P. berghei. Also, mice immunized with Bm8 polypeptide had a decreased parasite burden after B. microti or P. berghei infection.ConclusionsPassive immunization with Bm8 antisera could protect mice against B. microti or P. berghei infection to a certain extent. These results lead us to hypothesize that the B. microti conserved erythrocyte membrane-associated protein Bm8 could serve as a novel broad-spectrum parasite vaccine candidate since it elicits a protective immune response against Babesiosis and Plasmodium infection.Graphical

Impact of resveratrol and zinc on biomarkers of oxidative stress induced by Trichinella spiralis infection.

Trichinellosis is a re-emerging worldwide foodborne zoonosis. Oxidative stress is one of the most common detrimental effects caused by trichinellosis. In addition, Trichinella infection poses an infinite and major challenge to the host's immune system. Resistance and side effects limit the efficiency of the existing anti-trichinella medication. Given that concern, this work aimed to investigate the anti-helminthic, antioxidant, anti-inflammatory and immunomodulatory effects of resveratrol and zinc during both phases of Trichinella spiralis infection. Sixty-four Swiss albino mice were divided into four equal groups: non-infected control, infected control, infected and treated with resveratrol, and infected and treated with zinc. Animals were sacrificed on the 7th and 35th days post-infection for intestinal and muscular phase assessments. Drug efficacy was assessed by biochemical, parasitological, histopathological, immunological, and immunohistochemical assays. Resveratrol and zinc can be promising antiparasitic, antioxidant, anti-inflammatory, and immunomodulatory agents, as evidenced by the significant decrease in parasite burden, the significant improvement of liver and kidney function parameters, the increase in total antioxidant capacity (TAC), the reduction of malondialdehyde (MDA) level, the increase in nuclear factor (erythroid-derived 2)-like-2 factor expression, and the improvement in histopathological findings. Moreover, both drugs enhanced the immune system and restored the disturbed immune balance by increasing the interleukin 12 (IL-12) level. In conclusion, resveratrol and zinc provide protection for the host against oxidative harm and the detrimental effects produced by the host's defense response during Trichinella spiralis infection, making them promising natural alternatives for the treatment of trichinellosis.

Overwhelming Intravascular Hemolysis and Acute Renal Failure in Babesiosis Requiring Erythrocytapheresis

Babesia is an obligate intra-erythrocytic parasite transmitted by a tick called Ixodes scapularis . They invade erythrocytes and can present in various hematologic manifestations that can range from mild anemia to severe pancytopenia, splenic rupture, disseminated intravascular coagulation(DIC) or even hemophagocytic lymphohistocytosis1. They are typically self limiting in immunocompetent hosts, however management in splenectomized patients is complex and requires multidisciplinary care. We present the case of a 60 year old homeless male with a history of splenectomy secondary to a motor vehicle accident 6 years ago who presented to us with severe sepsis. On arrival his systolic blood pressure was in low 90s, tachycardic, tachypneic and saturating 93% on room air. Initial labs were significant for hyponatremia (125), hyperkalemia (5.6), acute renal failure (creatinine 2.18, baseline 0.8-1 and GFR 32, baseline 96-98), hyperuricemia(12.5), hyperphosphatemia(5) with congruent hypocalcemia(7.3).On blood counts hemoglobin(hb) was noted at 9.2 with baseline of 15 with appropriate reticulocytosis, leukocytosis(17.4) with monocytosis(26, normal is less than 11). Other labs include lactate dehydrogenase(LDH) which was elevated five times the normal limit(852) and serum haptoglobin was less than 8 (normal:11-44). He was appropriately fluid resuscitated and started on vancomycin and cefepime by emergency department. Overnight, a critical lab result was received, peripheral smear(pic 1) was showing intraerythrocytic parasites. By next morning, hematology confirmed the presence of Maltese cross on peripheral smear and parasite burden was determined at 20%. We subsequently transitioned the patient to atovaquone 750mg twice daily and IV azithromycin 500 mg daily. Doxycycline 100mg BID was later added by Infectious diseases(ID)to the regimen to empirically cover Lyme disease as both babesia and borrelia share the same tick vector. By day 2 of hospitalization patient was producing less than 0.5ml/kg/hour of urine output with decrease in GFR to 16 and concomitant rise in creatinine to 3.86, hb dropped to 7.8 with with notable rise in LDH(1080). Hematology opined for an urgent exchange transfusion specifically erythrocytapheresis and IR was consulted for a peripherally inserted central catheter insertion for the same. Post exchange transfusion, patient was noted to have improving kidney functions with decrease in parasite burden on serial peripheral smears. His hb remained stable around 10 and GFR improved to 63, at which point he was deemed stable for discharge. ID stepped down therapy to oral azithromycin 500mg daily and atovaquone 750 mg BID and doxycycline for total duration of two weeks at discharge. The indications of exchange transfusion in severe babesiosis are not well established. Erythrocytapheresis is typically considered in patients with severe hemolysis (hb less than 10), parasitemia greater than 10% or organ failure. However we did not find any prospective randomized studies to support this approach. The data to support erythrocytapheresis versus whole blood or plasma exchange is limited at best in immunocompetent patients2,3,4,5 .Though it should be noted that a prompt reduction in parasitemia markedly improves mortality in immunocompromised patient such as ours especially when used adjunctively to antimicrobial therapy 6.

Oceanimonas sp. BPMS22-derived protein protease inhibitor induces anti-leishmanial immune responses through macrophage M2 to M1 repolarization

The present study aimed to validate the potential of a novel serine protein protease inhibitor (PPI), purified from marine Oceanimonas sp. BPMS22, induced M2 to M1 repolarization of the macrophages to treat visceral leishmaniasis (VL). Peptide mass fingerprint of the purified trypsin digested PPI peptide was obtained using matrix-assisted laser desorption ionization-time of flight combined with tandem mass spectrometry (MALDI-TOF MS/MS) and the sequence was used to construct a 3D protein model by homology modelling. The IC50 of PPI were 25.28 ± 1.675 μg/mL and 0.415 ± 0.015 μg/mL against promastigotes and intracellular amastigotes, respectively, indicating the host-directed therapy using PPI. The PPI enhanced the effector molecule i.e., nitric oxide (NO), and dampened the arginase activity in a dose-dependent manner. In vitro studies revealed that the BPMS22-derived PPI significantly (p < 0.05) decreased the mRNA expressions of M2 markers (FIZZ-1, YM-1, CD206, Arg-1) and increased the mRNA expressions of M1 markers (iNOS, IL-1β, IL-12) in rIL-4 + rIL-10 induced M2 macrophages. Interestingly, the BPMS22-derived PPI also significantly (p < 0.05) decreased the FIZZ-1, YM-1, CD206, and Arg-1; significantly (p < 0.05) increased iNOS, IL-12, and IFN-γ mRNA expression in L. donovani -infected murine macrophages, alongside the decreased parasite load in it. Hence, PPI has the potential to repolarize the cytokines (rIL-4 + rIL-10) pre-stimulated and L. donovani-infected M2 macrophages to M1 phenotype in vitro. A decrease in parasite burden after treatment with PPI indicated the acceleration of the parasite killing by enhancing the macrophage effector functions. Further, in vivo PPI treatment reduced hepatic and splenic Leishman donovan units (LDU) up to 93.34 % and 87.63 %, respectively. This was followed by a surge in pro-inflammatory cytokines and dampening anti-inflammatory cytokines (p < 0.01), which exhibited anti-VL immunity. These observations might open new perspectives on PPI in macrophage repolarization to treat VL.

Regulatory role of Transcription factor-EB (TFEB) in parasite control through alteration of antigen presentation in visceral leishmaniasis

Leishmania donovani, an obligate intracellular parasite, the causative agent of visceral leishmaniasis is known to subvert the host immune system for its own survival. Although the precise mechanism is still unknown, emerging evidences indicate that L. donovani efficiently suppress MHC I mediated antigen presentation, rendering inadequate CD8+T cell activation and weakening host defense against parasite. The role of transcription factor EB (TFEB) was recognized in modulating antigen presentation besides its role in lysosomal biogenesis and function. Here, we investigated the regulatory role of TFEB in the modulation of presentation of Leishmania antigen in host tissue. Our results showed an increased expression of TFEB after Leishmania infection both in vitro and in vivo and there was a decrease in the expression of Th-1 cytokine IFNγ along with MHC class I and CD8+T cells indicating attenuation of cell mediated immunity and possibly MHC I restricted antigen presentation. Silencing of TFEB resulted in increased expression of IFNγ and MHC I along with increased CD8+T cells population without any significant change in CD4+T cell number. We also observed a decreased parasite burden in TFEB silenced condition which indicates enhanced parasite clearance by alteration of immunological response possibly through induction of presentation of Leishmania antigen through MHC I. The present study explains the role of TFEB silencing in parasite clearance through regulating the antigen presentation of Leishmania antigen thereby promises to formulate a potential therapeutic strategy against visceral leishmaniasis.

Translationally Controlled Tumor Protein-Mediated Stabilization of Host Antiapoptotic Protein MCL-1 Is Critical for Establishment of Infection by Intramacrophage Parasite Leishmania donovani.

In the early phase of infection, the intramacrophage pathogen Leishmania donovani protects its niche with the help of the antiapoptotic protein myeloid cell leukemia-1 (MCL-1). Whether Leishmania could exploit MCL-1, an extremely labile protein, at the late phase is still unclear. A steady translational level of MCL-1 observed up to 48 h postinfection and increased caspase-3 activity in MCL-1-silenced infected macrophages documented its importance in the late hours of infection. The transcript level of MCL-1 showed a sharp decline at 6 h postinfection, and persistent MCL-1 expression in cyclohexamide-treated cells negates the possibility of de novo protein synthesis, thereby suggesting infection-induced stability. Increased ubiquitination, a prerequisite for proteasomal degradation of MCL-1, was also found to be absent in the late hours of infection. Lack of interaction with its specific E3 ubiquitin ligase MULE (MCL-1 ubiquitin ligase E3) and specific deubiquitinase USP9X prompted us to search for blockade of the ubiquitin-binding site in MCL-1. To this end, TCTP (translationally controlled tumor protein), a well-known binding partner of MCL-1 and antiapoptotic regulator, was found to be strongly associated with MCL-1 during infection. Phosphorylation of TCTP, a requirement for MCL-1 binding, was also increased in infected macrophages. Knockdown of TCTP decreased MCL-1 expression and short hairpin RNA-mediated silencing of TCTP in an infected mouse model of visceral leishmaniasis showed decreased parasite burden and induction of liver cell apoptosis. Collectively, our investigation revealed a key mechanism of how L. donovani exploits TCTP to establish infection within the host.

Biofunctionalized Chrysin-conjugated gold nanoparticles neutralize Leishmania parasites with high efficacy.

Current treatments for leishmaniasis involve various drugs, including miltefosine and amphotericin B, which are associated with several side effects and high costs. Long-term use of these drugs may lead to the development of resistance, thereby reducing their efficiency. Chrysin (CHY) is a well-known, non-toxic flavonoid with antioxidant, antiviral, anti-inflammatory, anti-cancer, hepatoprotective, and neuroprotective properties. Recently we have shown that CHY targets the MAP kinase 3 enzyme of Leishmania and neutralizes the parasite rapidly. However, CHY is associated with low bioavailability, poor absorption, and rapid excretion issues, limiting its usage. In this study, we developed and tested a novel CHY-gold nanoformulation with improved efficacy against the parasites. The reducing power of CHY was utilized to reduce and conjugate with gold nanoparticles. Gold nanoparticles, which are already known for their anti-leishmanial properties, along with conjugated CHY, exhibited a decreased parasite burden in mammalian macrophages. Our findings showed that this biofunctionalized nanoformulation could be used as a potential therapeutic tool against leishmaniasis.

Enhancing Immune Responses to a DNA Vaccine Encoding Toxoplasma gondii GRA7 Using Calcium Phosphate Nanoparticles as an Adjuvant.

Toxoplasma gondii infects almost all warm-blooded animals, including humans. DNA vaccines are an effective strategy against T. gondii infection, but these vaccines have often been poorly immunogenic due to the poor distribution of plasmids or degradation by lysosomes. It is necessary to evaluate the antigen delivery system for optimal vaccination strategy. Nanoparticles (NPs) have been shown to modulate and enhance the cellular humoral immune response. Here, we studied the immunological properties of calcium phosphate nanoparticles (CaPNs) as nanoadjuvants to enhance the protective effect of T. gondii dense granule protein (GRA7). BALB/c mice were injected three times and then challenged with T. gondii RH strain tachyzoites. Mice vaccinated with GRA7-pEGFP-C2+nano-adjuvant (CaPNs) showed a strong cellular immune response, as monitored by elevated levels of anti-T. gondii-specific immunoglobulin G (IgG), a higher IgG2a-to-IgG1 ratio, elevated interleukin (IL)-12 and interferon (IFN)-γ production, and low IL-4 levels. We found that a significantly higher level of splenocyte proliferation was induced by GRA7-pEGFP-C2+nano-adjuvant (CaPNs) immunization, and a significantly prolonged survival time and decreased parasite burden were observed in vaccine-immunized mice. These data indicated that CaPN-based immunization with T. gondii GRA7 is a promising approach to improve vaccination.

Decreased parasite burden and altered host response in children with sickle cell anemia and severe anemia with malaria

AbstractPlasmodium falciparum malaria causes morbidity and mortality in African children with sickle cell anemia (SCA), but comparisons of host responses to P falciparum between children with SCA (homozygous sickle cell disease/hemoglobin SS [HbSS]) and normal hemoglobin genotype/hemoglobin AA (HbAA) are limited. We assessed parasite biomass and plasma markers of inflammation and endothelial activation in children with HbAA (n = 208) or HbSS (n = 22) who presented with severe anemia and P falciparum parasitemia to Mulago Hospital in Kampala, Uganda. Genotyping was performed at study completion. No child had known SCA at enrollment. Children with HbSS did not differ from children with HbAA in peripheral parasite density, but had significantly lower sequestered parasite biomass. Children with HbSS had greater leukocytosis but significantly lower concentrations of several plasma inflammatory cytokines, including tumor necrosis factor α (TNF-α). In contrast, children with HbSS had threefold greater concentrations of angiopoietin-2 (Angpt-2), a marker of endothelial dysregulation associated with mortality in severe malaria. Lower TNF-α concentrations were associated with increased risk of postdischarge mortality or readmission, whereas higher Angpt-2 concentrations were associated with increased risk of recurrent clinical malaria. Children with SCA have decreased parasite sequestration and inflammation but increased endothelial dysregulation during severe anemia with P falciparum parasitemia, which may ameliorate acute infectious complications but predispose to harmful long-term sequelae.

Bird-feeder cleaning lowers disease severity in rural but not urban birds

Animals inhabiting urban areas often experience elevated disease threats, putatively due to factors such as increased population density and horizontal transmission or decreased immunity (e.g. due to nutrition, pollution, stress). However, for animals that take advantage of human food subsidies, like feeder-visiting birds, an additional mechanism may include exposure to contaminated feeders as fomites. There are some published associations between bird feeder presence/density and avian disease, but to date no experimental study has tested the hypothesis that feeder contamination can directly impact disease status of visiting birds, especially in relation to the population of origin (i.e. urban v. rural, where feeder use/densities naturally vary dramatically). Here we used a field, feeder-cleaning experimental design to show that rural, but not urban, house finches (Haemorhous mexicanus) showed increased infection from a common coccidian endoparasite (Isospora spp.) when feeders were left uncleaned and that daily cleaning (with diluted bleach solution) over a 5-week period successfully decreased parasite burden. Moreover, this pattern in rural finches was true for males but not females. These experimental results reveal habitat- and sex-specific harmful effects of bird feeder use (i.e. when uncleaned in rural areas). Our study is the first to directly indicate to humans who maintain feeders for granivorous birds that routine cleaning can be critical for ensuring the health and viability of visiting avian species.

Antibody Levels to Plasmodium falciparum Erythrocyte Membrane Protein 1-DBLγ11 and DBLδ-1 Predict Reduction in Parasite Density.

ABSTRACTPlasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a variant surface antigen family expressed on infected red blood cells that plays a role in immune evasion and mediates adhesion to vascular endothelium. PfEMP1s are potential targets of protective antibodies as suggested by previous seroepidemiology studies. Here, we used previously reported proteomic analyses of PfEMP1s of clinical parasite isolates collected from Malian children to identify targets of immunity. We designed a peptide library representing 11 PfEMP1 domains commonly identified on clinical isolates by membrane proteomics and then examined peptide-specific antibody responses in Malian children. The number of previous malaria infections was associated with development of PfEMP1 antibodies to peptides from domains CIDRα1.4, DBLγ11, DBLβ3, and DBLδ1. A zero-inflated negative binomial model with random effects (ZINBRE) was used to identify peptide reactivities that were associated with malaria risk. This peptide selection and serosurvey strategy revealed that high antibody levels to peptides from DBLγ11 and DBLδ1 domains correlated with decreased parasite burden in future infections, supporting the notion that specific PfEMP1 domains play a role in protective immunity.IMPORTANCE Plasmodium infection causes devastating disease and high mortality in young children. Immunity develops progressively as children acquire protection against severe disease, although reinfections and recrudescences still occur throughout life in areas of endemicity, partly due to parasite immunoevasion via switching of variant proteins such as Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) expressed on the infected erythrocyte surface. Understanding the mechanisms behind antibody protection can advance development of new therapeutic interventions that address this challenge. PfEMP1 domain-specific antibodies have been linked to reduction in severe malaria; however, the large diversity of PfEMP1 domains in circulating parasites has not been fully investigated. We designed representative peptides based on B cell epitopes of PfEMP1 domains identified in membranes of clinical parasite isolates and surveyed peptide-specific antibody responses among young Malian children in a longitudinal birth cohort. We examined previous infections and age as factors contributing to antibody acquisition and identified antibody specificities that predict malaria risk.

Toxoplasma gondii Proteasome Subunit Alpha Type 1 with Chitosan: A Promising Alternative to Traditional Adjuvant.

As an important zoonotic protozoan, Toxoplasma gondii (T. gondii) has spread around the world, leading to infections in one-third of the population. There is still no effective vaccine or medicine against T. gondii, and recombinant antigens entrapped within nanospheres have benefits over traditional vaccines. In the present study, we first expressed and purified T. gondii proteasome subunit alpha type 1 (TgPSA1), then encapsulated the recombinant TgPSA1 (rTgPSA1) in chitosan nanospheres (CS nanospheres, rTgPSA1/CS nanospheres) and incomplete Freund’s adjuvant (IFA, rTgPSA1/IFA emulsion). Antigens entrapped in CS nanospheres reached an encapsulation efficiency of 67.39%, and rTgPSA1/CS nanospheres showed a more stable release profile compared to rTgPSA1/IFA emulsion in vitro. In vivo, Th1-biased cellular and humoral immune responses were induced in mice and chickens immunized with rTgPSA1/CS nanospheres and rTgPSA1/IFA emulsion, accompanied by promoted production of antibodies, IFN-γ, IL-4, and IL-17, and modulated production of IL-10. Immunization with rTgPSA1/CS nanospheres and rTgPSA1/IFA emulsion conferred significant protection, with prolonged survival time in mice and significantly decreased parasite burden in chickens. Furthermore, our results also indicate that rTgPSA1/CS nanospheres could be used as a substitute for rTgPSA1/IFA emulsion, with the optimal administration route being intramuscular in mass vaccination. Collectively, the results of this study indicate that rTgPSA1/CS nanospheres represent a promising vaccine to protect animals against acute toxoplasmosis.

IL-33 promotes innate lymphoid cell-dependent IFN-γ production required for innate immunity to Toxoplasma gondii.

IL-33 is an alarmin required for resistance to the parasite Toxoplasma gondii, but its role in innate resistance to this organism is unclear. Infection with T. gondii promotes increased stromal cell expression of IL-33, and levels of parasite replication correlate with release of IL-33 in affected tissues. In response to infection, a subset of innate lymphoid cells (ILC) emerges composed of IL-33R+ NK cells and ILC1s. In Rag1-/-mice, where NK cells and ILC1 production of IFN-γ mediate innate resistance to T. gondii, the loss of the IL-33R resulted in reduced ILC responses and increased parasite replication. Furthermore, administration of IL-33 to Rag1-/- mice resulted in a marked decrease in parasite burden, increased production of IFN-γ, and the recruitment and expansion of inflammatory monocytes associated with parasite control. These protective effects of exogenous IL-33 were dependent on endogenous IL-12p40 and the ability of IL-33 to enhance ILC production of IFN-γ. These results highlight that IL-33 synergizes with IL-12 to promote ILC-mediated resistance to T. gondii.

Liposomal amphotericin B is more effective in polymorphic lesions of post kala-azar dermal leishmaniasis.

Post kala-azar dermal leishmaniasis (PKDL) is thought to be the reservoir of infection for visceral leishmaniasis in South Asia. The development of strategies for the diagnosis and treatment of PKDL are important for the implementation of the visceral leishmaniasis elimination program. Liposomal amphotericin B (L-AMB) has been an overwhelming success in the treatment of visceral leishmaniasis. However, the empirical three-week regimen of L-AMB proposed for PKDL was shown to be inadequate, especially in the macular variant. This study aimed to delineate response of the different variants of PKDL to L-AMB. Skin biopsies were collected from PKDL cases at disease presentation and upon completion of treatment with L-AMB. Parasite DNA was detected by Internal Transcribed Spacer-1 PCR (ITS-1 PCR) and quantified by amplification of parasite kDNA. CD68 + macrophages were estimated in tissue sections by immunohistochemistry. Treatment with L-AMB decreased the parasite load by 97% in polymorphic cases but only by 45% in macular cases. The median parasite load (89965 vs 5445 parasites/μg of genomic DNA) as well as infiltration by CD68+ cells before treatment was much greater in the polymorphic cases. Although monitoring of the parasite load for 12 months post-treatment would have been ideal, this was not possible owing to logistical issues as well as the invasive nature of biopsy collection procedure. A dramatic decrease in the parasite burden was noted in patients with polymorphic lesions. Although patients with macular disease also had a decrease in parasite burden, this was not as marked as in the polymorphic cases. There was also a significantly greater infiltration of CD68 + macrophages in polymorphic PKDL before therapy.

The potential therapeutic effect of adipose-derived mesenchymal stem cells in the treatment of cutaneous leishmaniasis caused by L. major in BALB/c mice

Leishmaniasis is one of the most neglected tropical infectious diseases in the world. The emergence of drug resistance and toxicity and the high cost of the available drugs with a lack of new anti-leishmanial drugs highlight the need to search for newer therapies with anti-leishmanial activities. Due to the mesenchymal stem cell (MSC) immunomodulatory capacity, they have been applied in a wide variety of disorders. In this study, the potential effects of adipose-derived MSC (AD-MSCs) therapy and its combination with glucantime were evaluated in a murine model of cutaneous leishmaniasis induced by L. major. The results showed that AD-MSCs improved wound healing and decreased parasite burden. The real-time PCR results obtained from mice treated with AD-MSCs showed that IL-12 and TNF-α genes were upregulated. IL-10, arginase, and FOXP3 genes were downregulated whereas no differences in expression of the IL-4 gene were found. Overall, it seems that AD-MSCs therapy enhances Th1 immune response in L. major infected BALB/c mice. Unexpectedly, our results showed that the association of glucantime to AD-MSCs treatments did not lead to an increment in the anti-leishmanial activity.

Gut Microbiota Composition Modulates the Magnitude and Quality of Germinal Centers during Plasmodium Infections

SUMMARYGut microbiota composition is associated with human and rodent Plasmodium infections, yet the mechanism by which gut microbiota affects the severity of malaria remains unknown. Humoral immunity is critical in mediating the clearance of Plasmodium blood stage infections, prompting the hypothesis that mice with gut microbiota-dependent decreases in parasite burden exhibit better germinal center (GC) responses. In support of this hypothesis, mice with a low parasite burden exhibit increases in GC B cell numbers and parasite-specific antibody titers, as well as better maintenance of GC structures and a more targeted, qualitatively different antibody response. This enhanced humoral immunity affects memory, as mice with a low parasite burden exhibit robust protection against challenge with a heterologous, lethal Plasmodium species. These results demonstrate that gut microbiota composition influences the biology of spleen GCs as well as the titer and repertoire of parasite-specific antibodies, identifying potential approaches to develop optimal treatments for malaria.

Increased host ATP efflux and its conversion to extracellular adenosine is crucial for establishing Leishmania infection.

Intracellular survival of Leishmania donovani demands rapid production of host ATP for its sustenance. However, a gradual decrease in intracellular ATP in spite of increased glycolysis suggests ATP efflux during infection. Accordingly, upon infection, we show here that ATP is exported and the major exporter was pannexin-1, leading to raised extracellular ATP levels. Extracellular ATP shows a gradual decrease after the initial increase, and analysis of cell surface ATP-degrading enzymes revealed induction of the ectonucleotidases CD39 and CD73. Ectonucleotidase-mediated ATP degradation leads to increased extracellular adenosine (eADO), and inhibition of CD39 and CD73 in infected cells decreased adenosine concentration and parasite survival, documenting the importance of adenosine in infection. Inhibiting adenosine uptake by cells did not affect parasite survival, suggesting that eADO exerts its effect through receptor-mediated signalling. We also show that Leishmania induces the expression of adenosine receptors A2AR and A2BR, both of which are important for anti-inflammatory responses. Treating infected BALB/c mice with CD39 and CD73 inhibitors resulted in decreased parasite burden and increased host-favourable cytokine production. Collectively, these observations indicate that infection-induced ATP is exported, and after conversion into adenosine, propagates infection via receptor-mediated signalling.

Permethrin Cream for the Treatment of Demodex Blepharitis.

To evaluate the safety and efficacy of permethrin 5% cream for the treatment of Demodex blepharitis. Patients with confirmed Demodex blepharitis were prospectively recruited and treated with permethrin 5% cream for 6 months. Blepharitis symptoms, ocular examination findings, ocular surface disease index, and ex vivo eyelash Demodex counts were regularly assessed. Twenty-three patients were recruited, of which 2 were lost to follow up and 21 entered the analysis. Mean patient age was 57.2 ± 16.8 years (range: 24-82 years), and 13 (62%) were women. Mean Demodex counts improved after treatment from 1.36 ± 1.233 to 0.48 ± 0.6 parasites per eyelash (P = 0.03), and the overall blepharitis symptoms score improved from 42.9 ± 22 to 32.7 ± 21 (P = 0.01). Improvement in disease symptoms (scored on a scale between 0 and 4) was noted including feeling of dry eye (2.85 ± 1.3-1.85 ± 1.7, P = 0.006), discharge (1.86 ± 1.7-1.00 ± 1.1, P = 0.040), and dandruff-like debris (1.69 ± 1.7-0.9 ± 1.6, P = 0.033), as well as clinical findings including a decrease in scaling (on a scale of 1-5; 1.43 ± 0.9-0.86 ± 0.7, P = 0.006) and corneal staining with fluorescein (on a scale of 1-4; 1.29 ± 0.4-1.05 ± 0.2, P = 0.040). No change in the ocular surface disease index score was noted (37.5 ± 24.1-41.63 ± 42.5, P = 0.913), and no adverse events were reported. Treatment of Demodex blepharitis with permethrin 5% cream resulted in a decrease in parasite burden and improvement in blepharitis signs and symptoms, with no reported adverse events. Permethrin might be a safe and effective alternative for the treatment of blepharitis associated with Demodex infection.