Drug Targeting to Macrophages With Solid Lipid Nanoparticles Harboring Paromomycin: an In Vitro Evaluation Against L. major and L. tropica

Nanoemulsions containing amphotericin b and paromomycin for the treatment of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a vector-borne disease characterized by skin lesions that can evolve into high-magnitude ulcerated lesions. Thus, this study aimed to develop an innovative nanoemulsion (NE) with clove oil, Poloxamer® 407, and multiple drugs, such as amphotericin B (AmB) and paromomycin (PM), for use in the topical treatment of CL.

METHODS

Droplet size, morphology, drug content, stability, in vitro release profile, in vitro cytotoxicity on RAW 264.7 macrophages, and antileishmanial activity using axenic amastigotes of Leishmania amazonensis were assessed for NEs.

RESULTS

After optimizing the formulation parameters, such as the concentration of clove oil and drugs, using an experimental design, it was possible to obtain a NE with an average droplet size of 40 nm and a polydispersion index of 0.3, and these parameters were maintained throughout the 365 days. Furthermore, the NE showed stability of AmB and PM content for 180 days under refrigeration (4 °C), presented a pH compatible with the skin, and released modified AmB and PM. NE showed the same toxicity as free AmB and higher toxicity than free PM against RAW 264.7 macrophages. The same activity as free AmB, and higher activity than free PM against amastigotes L. amazonensis.

CONCLUSION

It is possible to develop a NE for the treatment of CL; however, complementary studies regarding the antileishmanial activity of NE should be carried out.

Development of solid lipid nanoparticles-loaded drugs in parasitic diseases

Parasites cause illnesses with broad spectrum of symptoms from mild to severe, and are responsible for a significant number of outbreaks in the world. Current anti-parasitic drugs are toxic and have significant side effects. Nano-carriers are believed to obviate the limitations of conventional drugs via decreasing side effects and increasing target delivery and drug permeability with a controlled prolonged release of a drug. Solid lipid nanoparticles (SLNs) are lipid nanoparticles (LNPs), which have frequently been practiced. Suitable release rate, stability, and target delivery make SLNs a good alternative for colloidal carriers. SLNs are supposed to have great potential to deliver natural products with anti-parasitic properties. Nanoparticles have employed to improve stability and capacity loading of SLNs, during recent years. This review describes development of SLNs, the methods of preparation, characterization, and loaded drugs into SLNs in parasitic diseases. In addition, we summarize recent development in anti-parasitic SLNs-loaded drugs.

Treatment of superficial and deep partial width second degree burn's wound with allogeneic cord blood platelet gel

BACKGROUND

Burns are caused by a variety of mechanisms, including flames, hot liquids, metallurgy, chemicals, electric current, and ionizing and non-ionizing radiation. The most significant burn wound management involves complete repair and regeneration as soon as possible while minimizing infection, contraction, and scarring in the damaged tissue area. Some factors such as delivery of nutrients, growth factors, and oxygen are essential to promote and stimulate the wound healing progress in the burns area. When these factors are not provided, the burn wound undergoes a physiological crisis. The use of growth factors is a promising approach to overcoming this limitation. Umbilical cord blood platelet concentrates are a rich natural source of growth factors.

METHODS

This clinical trial used growth factors released from the lysis of umbilical cord blood platelet concentrates that have a key role in promoting re-epithelization and regeneration of damaged tissues by forming a fibrin network. This study evaluated the effectiveness of allogeneic cord blood platelet gel topical dressing in a group of patients diagnosed with superficial and deep partial thickness (second-degree) burn wounds. Clinical outcomes were compared between the intervention group and a control group of patients with superficial second-degree burn wounds who received the standard routine treatment including paraffin gauze wound dressing and silver sulfadiazine ointment.

RESULTS

The study's results showed that the increased rate of recovery and tissue granulation completely promoted to wound healing and burn wound closure, decreased the recovery time, and reduced inflammation and scars caused by burn injuries. However, the use of cord blood platelet gel topical dressing is not currently a routine treatment method in patients suffering from burn wounds. However, the study's results showed that allogenic cord blood platelet gel could be used to treat superficial and deep second-degree burns as a routine treatment. It was also shown that allogenic cord blood platelet gel topical dressing could be a candidate for autograft or after autograft skin transplantation surgery (in donor and recipient sites) instead of skin surgery in some patients.

CONCLUSION

Allogeneic topical wound dressing provides an effective treatment that offers a faster rate of epithelialization and healing of wounds and also decreases patients' scar and inflammation level as well as the length of recovery time. This, finally, leads to better burn wound management and the improved quality of burn wound treatment.

A Systematic Review of Drug-Carrying Nanosystems Used in the Treatment of Leishmaniasis

Leishmaniasis is an infectious disease responsible for a huge rate of morbidity and mortality in humans. Chemotherapy consists of the use of pentavalent antimonial, amphotericin B, pentamidine, miltefosine, and paromomycin. However, these drugs are associated with some drawbacks such as high toxicity, administration by parenteral route, and most seriously the resistance of some strains of the parasite to them. Several strategies have been used to increase the therapeutic index and reduce the toxic effects of these drugs. Among them, the use of nanosystems that have great potential as a site-specific drug delivery system stands out. This review aims to compile results from studies that were carried out using first- and second-line antileishmanial drug-carrying nanosystems. The articles referred to here were published between 2011 and 2021. This study shows the promise of effective applicability of drug-carrying nanosystems in the field of antileishmanial therapeutics, with the perspective of providing better patient adherence to treatment, increased therapeutic efficacy, reduced toxicity of conventional drugs, as well as the potential to efficiently improve the treatment of leishmaniasis.

Antileishmanial Activities of ( Z )-2-(Nitroimidazolylmethylene)-3( 2H )-Benzofuranones: Synthesis, In Vitro Assessment, and Bioactivation by NTR 1 and 2

The antileishmanial activity of a series of ( Z )-2-(heteroarylmethylene)-3(2 H )-benzofuranone derivatives, possessing 5-nitroimidazole or 4-nitroimidazole moieties, was investigated against Leishmania major promastigotes and some analogues exhibited prominent activities. Compounds with IC 50 values lower than 20 μM were further examined against L. donovani axenic amastigotes.

Nanomedicine-based strategies to improve treatment of cutaneous leishmaniasis

Nanomedicine strategies were first adapted and successfully translated to clinical application for diseases, such as cancer and diabetes. These strategies would no doubt benefit unmet diseases needs as in the case of leishmaniasis. The latter causes skin sores in the cutaneous form and affects internal organs in the visceral form. Treatment of cutaneous leishmaniasis (CL) aims at accelerating wound healing, reducing scarring and cosmetic morbidity, preventing parasite transmission and relapse. Unfortunately, available treatments show only suboptimal effectiveness and none of them were designed specifically for this disease condition. Tissue regeneration using nano-based devices coupled with drug delivery are currently being used in clinic to address diabetic wounds. Thus, in this review, we analyse the current treatment options and attempt to critically analyse the use of nanomedicine-based strategies to address CL wounds in view of achieving scarless wound healing, targeting secondary bacterial infection and lowering drug toxicity.

Anti-Leishmanial Activity of Artemisia persica, A. spicigera, and A. fragrance against Leishmania major

Background:

Neglected tropical diseases (NTDs) like zoonotic cutaneous leishmaniasis (ZCL), is a widespread infectious disease with high mortality and morbidity. Various medications are used for treating the disease, but several side effects and drug resistance have been reported. Herbal medicines are unlimited sources for discovering new medications to treat infectious diseases. We aimed to determine the leishmanicidal activity of three species of Iranian Artemisia herbal plant extracts in in-vitro.

Methods:

In-vitro anti-leishmanial activity of ethanolic extracts on both promastigotes and amastigotes was determined by using MTT method. IC50, CC50, EC50 and SI were calculated. The study was done in 2019-2020 in Iran University of Medical Sciences, Tehran, Iran.

Results:

All of the three Artemisia species significantly reduced the number of parasite promastigotes. Among them, A. persica had the highest leishmanicidal activity against parasite promastigotes. Cytotoxicity assay elucidated that the Artemisia had no toxicity to the host cells, and killed the L. major amastigotes very efficiently. By increasing the dose of extracts, the parasite number in both phases (promastigotes and amastigotes) was reduced significantly.

Conclusion:

These results indicated satisfactory anti-leishmanial activity of Artemisia extracts against ZCL in-vitro. Accordingly, Artemisia ethanolic extracts might be considered as a strong, effective and safe herbal compound for clearing the L. major with less toxicity to the host macrophages cells. Hence, it may be recognized as an excellent herbal therapy for treating the ZCL.

Nanotechnology-aided diagnosis, treatment and prevention of leishmaniasis

Leishmaniasis is a prevalent parasitic infection belonging to neglected tropical diseases. It is caused by Leishmania protozoan parasites transmitted by sandflies and it is responsible for increased morbidity/mortality especially in low- and middle-income countries. The lack of cheap, portable, easy to use diagnostic tools exhibiting high efficiency and specificity impede the early diagnosis of the disease. Furthermore, the typical anti-leishmanial agents are cytotoxic, characterized by low patient compliance and require long-term regimen and usually hospitalization. In addition, due to the intracellular nature of the disease, the existing treatments exhibit low bioavailability resulting in low therapeutic efficacy. The above, combined with the common development of resistance against the anti-leishmanial agents, denote the urgent need for novel therapeutic strategies. Furthermore, the lack of effective prophylactic vaccines hinders the control of the disease. The development of nanoparticle-based biosensors and nanocarrier-aided treatment and vaccination strategies could advance the diagnosis, therapy and prevention of leishmaniasis. The present review intends to highlight the various nanotechnology-based approaches pursued until now to improve the detection of Leishmania species in biological samples, decrease the side effects and increase the efficacy of anti-leishmanial drugs, and induce enhanced immune responses, specifically focusing on the outcome of their preclinical and clinical evaluation.

Solid lipid nanoparticles as a novel formulation approach for tanespimycin (17-AAG) against leishmania infections: Preparation, characterization and macrophage uptake

17-N-allylamino-17-demethoxygeldanamycin (17-AAG, tanespimycin) is an inhibitor of heat shock protein 90 (Hsp90), which has been studied in the treatment of cancer such as leukemia or solid tumors. Alternatively, 17-AAG may represent a promising therapeutic agent against leishmaniasis. However, the delivery of 17-AAG is difficult due to its poor aqueous solubility. For exploring the therapeutic value of 17-AAG, we developed solid lipid nanoparticles (SLN) by double emulsion method. SLN exhibited ~100 nm, PDI < 0.2 and zeta potential ~20 mV. In addition, SLN were morphologically spherical with negligible aggregation. The entrapment efficiency of 17-AAG into the lipid matrix reached at nearly 80%. In a separate set of experiments, fluorescent SLN (FITC-labeled) showed a remarkable macrophage uptake, peaking within 2 h of incubation by confocal microscopy. Regarding the drug internalization as critical step for elimination of intracellular Leishmania, this finding demonstrates an important feature of the developed SLN. Collectively, these data indicate the feasibility of developing SLN as potential delivery systems for 17-AAG in leishmaniasis chemotherapy.

Modified solid lipid nanoparticles encapsulated with Amphotericin B and Paromomycin: an effective oral combination against experimental murine visceral leishmaniasis

The development of an effective oral therapeutics is an immediate need for the control and elimination of visceral leishmaniasis (VL). We exemplify the preparation and optimization of 2-hydroxypropyl-β-cyclodextrin (HPCD) modified solid lipid nanoparticles (SLNs) based oral combinational cargo system of Amphotericin B (AmB) and Paromomycin (PM) against murine VL. The emulsion solvent evaporation method was employed to prepare HPCD modified dual drug-loaded solid lipid nanoparticles (m-DDSLNs). The optimized formulations have a mean particle size of 141 ± 3.2 nm, a polydispersity index of 0.248 ± 0.11 and entrapment efficiency for AmB and PM was found to be 96% and 90% respectively. The morphology of m-DDSLNs was confirmed by scanning electron microscopy and transmission electron microscopy. The developed formulations revealed a sustained drug release profile upto 57% (AmB) and 21.5% (PM) within 72 h and were stable at both 4 °C and 25 °C during short term stability studies performed for 2 months. Confocal laser scanning microscopy confirmed complete cellular internalization of SLNs within 24 h of incubation. In vitro cytotoxicity study against J774A.1 macrophage cells confirmed the safety and biocompatibility of the developed formulations. Further, m-DDSLNs did not induce any hepatic/renal toxicities in Swiss albino mice. The in vitro simulated study was performed to check the stability in simulated gastric fluids and simulated intestinal fluids and the release was found almost negligible. The in vitro anti-leishmanial activity of m-DDSLNs (1 µg/ml) has shown a maximum percentage of inhibition (96.22%) on intra-cellular amastigote growth of L. donovani. m-DDSLNs (20 mg/kg × 5 days, p.o.) has significantly (P < 0.01) reduced the liver parasite burden as compared to miltefosine (3 mg/kg × 5 days, p.o.) in L. donovani-infected BALB/c mice. This work suggests that the superiority of as-prepared m-DDSLNs as a promising approach towards the oral delivery of anti-leishmanial drugs.

Preparation and Characterization of Nanostructured Lipid Carriers for Improved Topical Drug Delivery: Evaluation in Cutaneous Leishmaniasis and Vaginal Candidiasis Animal Models

The present study aimed to develop, characterize and evaluate the amphotericin B-loaded nanostructured lipid carriers (AmB-NLCs) for topical treatment of cutaneous leishmaniasis (CL) and vulvovaginal candidiasis (VVC). AmB-NLCs were characterized for particle size, zeta potential, encapsulation efficiency and surface morphology. Prepared NLCs were also characterized for in vitro drug release, ex vivo skin permeation and deposition before evaluating their in vitro and in vivo efficacy. Cytotoxicity of NLCs was assessed on MRC-5 cells, whereas skin irritation potential was evaluated in vivo using rats. Significant accumulation of drug in to the skin supported the topical application potential of drug-loaded NLCs. Encapsulation of AmB in NLCs resulted in enhanced in vitro potency against promastigotes and intracellular amastigotes of L. major JISH 118 (IC50 ± SEM = 0.02 ± 0.1 μM for both) compared with free drug (IC50 ± SEM = 0.15 ± 0.2 & 0.14 ± 0.0, respectively). Similar improved potency of AmB-NLCs was also observed for other Leishmania and fungal strains compared with drug solution. Topical application of AmB-NLCs on L. major-infected BALB/c mice caused a significant reduction in parasite burden per mg of lesion (65 × 108 ± 13) compared with the control group (> 167.8 × 108 ± 11). Topical AmB-NLCs gel demonstrated superior efficacy in the vaginal C. albicans rat model for VVC as compared with plain AmB gel. Moreover, results of in vitro cytotoxicity assay and in vivo skin irritation test confirmed AmB-NLCs to be non-toxic and safe for topical use. In conclusion, NLCs may have promising potential as carrier for topical treatment of various conditions of skin and mucosa.

Nanoparticles for antiparasitic drug delivery

As an emerging novel drug carrier, nanoparticles provide a promising way for effective treatment of parasitic diseases by overcoming the shortcomings of low bioavailability, poor cellular permeability, nonspecific distribution and rapid elimination of antiparasitic drugs from the body. In recent years, some kinds of ideal nanocarriers have been developed for antiparasitic drug delivery. In this review, the progress of the enhanced antiparasitic effects of different nanoparticles payload and their influencing factors were firstly summarized. Secondly, the transport and disposition process in the body were reviewed. Finally, the challenges and prospects of nanoparticles for antiparasitic drug delivery were proposed. This review will help scholars to understand the development trend of nanoparticles in the treatment of parasitic diseases and explore strategies in the development of more efficient nanocarriers to overcome the difficulty in the treatment of parasite infections in the future.

Antileishmanial effect of rapamycin as an alternative approach to control Leishmania tropica infection

Cutaneous leishmaniosis (CL) is a parasitic disease in animals and human with no satisfactory treatments and vaccination. Rapamycin is a potent inhibitor of mammalian target of rapamycin (mTOR) with various applications. Here, the effect of rapamycin alone or in combination with two other drugs, namely amphotericin B (AmB) and glucantime, was investigated against Leishmania tropica infection. In vitro viability and electron microscopy evaluation of the parasites showed detrimental changes in their appearance and viability. Treatment with clinically relevant dose of rapamycin (10.2 μg/dose) is able to control the parasite load in BALB/c mice infected with L. tropica. Furthermore, the cytokine profiles showed significant polarization towards Th1 immune response. Surprisingly, combination therapy with either AmB or glucantime was not efficient. Rapamycin is showed an effective alternative therapy against leishmaniosis caused by L. tropica.

Paromomycin-loaded mannosylated chitosan nanoparticles: Synthesis, characterization and targeted drug delivery against leishmaniasis

Cutaneous leishmaniasis is the most common form of leishmaniasis caused by different species of Leishmania parasites. The emergence of resistance, toxicity, long term treatment, high cost of the current drugs, and intracellular nature of the parasite are the major difficulties for the treatment of leishmaniasis. Although the therapeutic effect of paromomycin (PM) on leishmaniasisLeishmania parasite). PM-loaded into mannosylated CS (MCS) nanoparticles using dextran (PM-MCS-dex-NPs) was prepared by ionic gelation and then characterized. The particle size and Zeta potential of PM-MCS-dex-NPs were obtained as 246 nm and + 31 mV, respectively. Mannosylation of CS was qualitatively evaluated by Fourier-transform infrared spectroscopy and quantitatively measured by CHNO elemental analysis; also, a mannosylation level of 17% (w) was attained. Encapsulation efficiency (EE), drug release profile, and THP-1 cell uptake potential were determined. A value of 83.5% for EE and a higher release rate in acidic media were achieved. THP-1 cell uptake level of PM-MCS-dex-NPs after 6 h was ˜2.8 and ˜3.9 times of non-mannosylated CS nanoparticles (PM-CS-dexIn vitroGlucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 1846 ± 158, 1234 ± 93, 784 ± 52 and 2714 ± 126 μg mL^-1Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 105.0 ± 14.0, 169.5 ± 9.8, 65.8 ± 7.3 and 17.8 ± 1.0 μg mL^-1Glucantim, PM-CS-dex-NPs and PM-MCS-dexGlucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs at a typical concentration of 20 μg mL^-1 were 71.78, 69.94, 83.14 and 33.41%, respectively. While the effect of PM-CS-dex-NPs was more salient on amastigotes, PM-MCS-dex-NPs effectively affected both stages of the parasite, especially the amastigote one. This indicated that the mannosylated formulation acts as a targeted delivery system. The findings of this study revealed that this novel targeted formulation represented a strong anti-leishmanial activity.

Paromomycin-loaded mannosylated chitosan nanoparticles: Synthesis, characterization and targeted drug delivery against leishmaniasis

Cutaneous leishmaniasis is the most common form of leishmaniasis caused by different species of Leishmania parasites. The emergence of resistance, toxicity, long term treatment, high cost of the current drugs, and intracellular nature of the parasite are the major difficulties for the treatment of leishmaniasis. Although the therapeutic effect of paromomycin (PM) on leishmaniasis has been investigated in different studies, it has a low oral absorption and short half-life, leading to a decreased drug efficacy. Therefore, new and targeted carriers with no such problems are needed. In the present study, PM was loaded into chitosan (CS) nanoparticles accompanied by targeting to macrophages (as the host of Leishmania parasite). PM-loaded into mannosylated CS (MCS) nanoparticles using dextran (PM-MCS-dex-NPs) was prepared by ionic gelation and then characterized. The particle size and zeta potential of PM-MCS-dex-NPs were obtained as 246 nm and +31 mV, respectively. Mannosylation of CS was qualitatively evaluated by Fourier-transform infrared spectroscopy and quantitatively measured by CHNO elemental analysis; also, a mannosylation level of 17% (w) was attained. Encapsulation efficiency (EE), drug release profile, and THP-1 cell uptake potential were determined. A value of 83.5% for EE and a higher release rate in acidic media were achieved. THP-1 cell uptake level of PM-MCS-dex-NPs after 6 h was ˜2.8 and ˜3.9 times of non-mannosylated CS nanoparticles (PM-CS-dex-NPs) and PM aqueous solution, respectively. In vitro cell cytotoxicity and promastigote and amastigote viabilities were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Half-maximal inhibitory concentration values toward the THP-1 cells for PM aqueous solution, Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 1846 ± 158, 1234 ± 93, 784 ± 52 and 2714 ± 126 μg mL^-1, respectively. Half-maximal inhibitory concentration values toward the promastigotes for PM aqueous solution, Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs after 48 h were obtained as 105.0 ± 14.0, 169.5 ± 9.8, 65.8 ± 7.3 and 17.8 ± 1.0 μg mL^-1, respectively. Selectivity (therapeutic) indices for PM aqueous solution, Glucantim, PM-CS-dex-NPs and PM-MCS-dex-NPs after 48 h were obtained as 24.6, 17.5, 3.7 and 214, respectively. The parasite burden in THP-1 cells after 48 h treatment with PM aqueous solution, Glucantim, PM-CS-dex-NPs, and PM-MCS-dex-NPs at a typical concentration of 20 μg mL^-1 were 71.78, 69.94, 83.14 and 33.41%, respectively. While the effect of PM-CS-dex-NPs was more salient on amastigotes, PM-MCS-dex-NPs effectively affected both stages of the parasite, especially the amastigote one. This indicated that the mannosylated formulation acts as a targeted delivery system. The findings of this study revealed that this novel targeted formulation represented a strong anti-leishmanial activity.

Innovative Solutions for the Control of Leishmaniases: Nanoscale Drug Delivery Systems

Background:

Leishmania are sandfly-transmitted protozoan parasites that harbour within the macrophages of a mammalian host and cause leishmaniasis, a serious zoonotic disease that threatens the lives of millions worldwide. Its numerous forms (cutaneous, mucocutaneous, and visceral) are currently treated with a sparse arsenal of drugs, specifically antimonials, amphotericin B, miltefosine, and paromomycin, for which drug resistance and clinical failure are rampant. Medicine is presently trending towards nanotechnology to aid in the successful delivery of drugs. Vehicles such as lipid-based nanocarriers, polymer-based nanoparticles, and metal ions and oxides have been previously demonstrated to improve bioavailability of drugs and decrease toxicity for the patient. These cutting-edge solutions can be combined with existing active molecules, as well as novel drugs or plant extracts with promising antileishmanial activity.

Conclusion:

This review explores the current evidence for the treatment of leishmaniases using nanoscale drug delivery systems (specifically lipid-, polymer- and metal-based systems) and encourages further development of the aforementioned nanotechnologies for treatment of Leishmania.

Improved antibacterial function of Rifampicin-loaded solid lipid nanoparticles on Brucella abortus

The objective of this study was to assess the antibacterial activity of Rifampicin-loaded solid lipid nanoparticles on Brucella abortus 544. Rifampicin-loaded solid lipid nanoparticles were prepared by a modified microemulsion/sonication method and characterized. The results showed the average size about 319.7 nm, PI about 0.20 and zeta potential about 18.4 mv, encapsulation efficacy and drug-loading were equal to 95.78 and 34.2%, respectively, with a spherical shape. Drug release lasted for 5 days. The antibacterial activity was statistically significant with p < .05 in bacterial and cell culture media compared to free Rifampicin. It can be concluded that solid lipid nanoparticles can be considered as a promising delivery system for improving the antibacterial activity of Rifampicin against Brucella abortus.

Leishmania tropica: What we know from its experimental models

Leishmania tropica causes different forms of leishmaniasis in many parts of the world. Animal models can help to clarify the issues of pathology and immune response in L. tropica infections and can be applied to the control, prevention and treatment of the disease. The aim of this article is to summarize published data related to experimental models of this parasite, presenting an overview of the subject. We also present in brief the epidemiology, transmission and human manifestation of L. tropica infection. Mice, rats and hamsters have been used for experimental models of L. tropica infection. Main findings of the published studies show that: (1) Hamsters are the best animal model for L. tropica infection, with the drawback of being outbred hence not suitable for many studies. (2) L. tropica infection causes a non-ulcerative and chronic pathology as cutaneous form in mice and usually visceral form in hamsters. (3) L. tropica infection in mice results in a weaker immune response in comparison to Leishmania major. (4) While the Th1 responses are evoked against L. tropica, Th2 responses do not explain the outcomes of this infection, and IL-10 and TGF-β are two main suppressive cytokines. (5) The host genotype affects the immune response and disease outcome of L. tropica infection and the dose, strain, routes of inoculation, and sex of the host are among the factors affecting disease outcome of this species.

Engineering the niche for hair regeneration - A critical review

Recent progress in hair follicle regeneration and alopecia treatment necessitates revisiting the concepts and approaches. In this sense, there is a need for shedding light on the clinical and surgical therapies benefitting from nanobiomedicine. From this perspective, this review attempts to recognize requirements upon which new hair therapies are grounded; to underline shortcomings and opportunities associated with recent advanced strategies for hair regeneration; and most critically to look over hair regeneration from nanomaterials and pluripotent stem cell standpoint. It is noteworthy that nanotechnology is able to illuminate a novel path for reprogramming cells and controlled differentiation to achieve the desired performance. Undoubtedly, this strategy needs further advancement and a lot of critical questions have yet to be answered. Herein, we introduce the salient features, the hurdles that must be overcome, the hopes, and practical constraints to engineer stem cell niches for hair follicle regeneration.

Therapeutic control of leishmaniasis by inhibitors of the mammalian target of rapamycin

Leishmaniasis is a serious global health problem affecting many people worldwide. While patients with leishmaniasis can be treated with several agents, drug toxicicty and the emergence of resistant strains render available treatments ineffective in the long run. Inhibitors of the mammalian target of rapamycin (mTOR) have been demonstrated to exert anti-pathogen properties. In this study, we tested the therapeutic efficacy of several mTOR inhibitors in controlling infection with Leishmania major. Rapamycin, GSK-2126458 and KU-0063794 were administered to BALB/c mice, which had received an intrafootpad injection of the parasite. Footpad swelling and parasite burden were assessed, and cytokine production by mouse splenocytes and phenotypic changes in draining lymph node cells were evaluated. Treatment with a clinically relevant dose of rapamycin or with GSK-2126458, but not with KU-0063794, dramatically lowered both the footpad swelling and the parasite load in the draining lymph node. Importantly, the employed dose of rapamycin did not kill the promastigotes in vitro as judged by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays and electron microscopy. Moreover, the IL-4 production capacity of splenocytes harvested from infected mice that were treated with rapamycin was significantly reduced. Consequently, the IFN-γ:IL-4 production ratio was elevated, suggesting a T helper-type 1 (Th1)-skewed cytokine profile. Finally, the expression level of CD69, an early activation marker, on splenic and lymph node CD4+ and CD8+ T cells was enhanced in rapamycin-treated mice. Taken together, our findings suggest that select mTOR inhibitors may be used in therapeutic settings for the management of leishmaniasis. We propose that the beneficial effects of such inhibitors stem from their immunomodulatory properties. Therefore, the adjuvanticity of mTOR inhibitors may also be considered in vaccination strategies against Leishmania species.

Arginase activity in pathogenic and non-pathogenic species of Leishmania parasites

Proliferation of Leishmania (L.) parasites depends on polyamine availability, which can be generated by the L-arginine catabolism and the enzymatic activity of arginase (ARG) of the parasites and of the mammalian hosts. In the present study, we characterized and compared the arginase (arg) genes from pathogenic L. major and L. tropica and from non-pathogenic L. tarentolae. We quantified the level of the ARG activity in promastigotes and macrophages infected with pathogenic L. major and L. tropica and non-pathogenic L. tarentolae amastigotes. The ARG's amino acid sequences of the pathogenic and non-pathogenic Leishmania demonstrated virtually 98.6% and 88% identities with the reference L. major Friedlin ARG. Higher ARG activity was observed in all pathogenic promastigotes as compared to non-pathogenic L. tarentolae. In vitro infection of human macrophage cell line (THP1) with pathogenic and non-pathogenic Leishmania spp. resulted in increased ARG activities in the infected macrophages. The ARG activities present in vivo were assessed in susceptible BALB/c and resistant C57BL/6 mice infected with L. major, L. tropica and L. tarentolae. We demonstrated that during the development of the infection, ARG is induced in both strains of mice infected with pathogenic Leishmania. However, in L. major infected BALB/c mice, the induction of ARG and parasite load increased simultaneously according to the time course of infection, whereas in C57BL/6 mice, the enzyme is upregulated solely during the period of footpad swelling. In L. tropica infected mice, the footpads' swellings were slow to develop and demonstrated minimal cutaneous pathology and ARG activity. In contrast, ARG activity was undetectable in mice inoculated with the non-pathogenic L. tarentolae. Our data suggest that infection by Leishmania parasites can increase ARG activity of the host and provides essential polyamines for parasite salvage and its replication. Moreover, the ARG of Leishmania is vital for parasite proliferation and required for infection in mice. ARG activity can be used as one of the main marker of the disease severity.