Antifouling and Antibacterial Polymer-Coated Surfaces Based on the Combined Effect of Zwitterions and the Natural Borneol

The development and application of natural antibacterial materials have always been the focus of biomedical research. Borneol as a natural antibacterial compound has received extensive attention. However, the hydrophobicity caused by its unique structure limits its application range to a certain extent. In this study, we combine zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) with a complex bicyclic monoterpene structure borneol compound and prepare an excellent antifouling and antibacterial surface via the Schiff-base bond. The prepared coating has excellent hydrophilicity verified by the contact angle (CA), and its polymer layer is confirmed by X-ray photoelectron spectroscopy (XPS). The zwitterion MPC and borneol moieties in the copolymer play a coordinating role, relying on super hydration and the special stereochemical structure to prevent protein adsorption and inhibit bacterial adhesion, respectively, which are demonstrated by bovine serum albumin (BSA) adsorption and antibacterial activity test. Moreover, the water-soluble borneol derivative as the antibacterial surfaces we designed here was biocompatible toward MRC-5 (lung fibroblasts), as showed by in vitro cytotoxicity assays. Such results indicate the potential application of the as-prepared hydrophilic surfaces in the biomedical materials.

MicroRNA-155-5p/EPAS1/interleukin 6 pathway participated in the protection function of sphingosylphosphorylcholine to ischemic cardiomyocytes

AIM

Previous research in our laboratory found that a biologically active sphingomyelin metabolite, sphingosylphosphorylcholine (SPC), can inhibit myocardial cell apoptosis caused by ischemia with an unknown mechanism. Here, we aimed to study the possible participation of EPAS1 in the protection process of SPC.

METHODS

The rat cardiomyocytes deprived of serum were used to mimic ischemic-caused apoptosis, then treated with or without SPC. The expression and nuclear shift of EPAS1 were detected by western blot and immunofluorescence, and its function was studied using its siRNA.

KEY FINDING

Our research shows that SPC inhibited serum starvation caused cardiomyocyte apoptosis, accompanied by the up-regulation and nucleus translocation of EPAS1. EPAS1 levels did not change when its transcript was blocked by Actinomycin D, which prompted us to search for a post-transcription mechanism for its increased expression, and finally found that miR-155-5p, regulated by STAT3, was a new post-transcription regulator to EPAS1. Further investigation found that EPAS1 participated in the protective effect of SPC is mainly achieved by activating the downstream target gene, interleukin-6 (IL-6).

SIGNIFICANCE

Our results expand our understanding of the biological functions of SPC, and bring a new pathway as a potential therapeutic target to the treatment of cardiovascular diseases caused by myocardial apoptosis.

Identification of Antifungal Bisphosphocholines from Medicinal Gentiana Species

Gentiana species including G. crassicaulis, G. macrophylla, G. dahurica, and G. straminea are used in traditional Chinese medicine as "Qinjiao" for the treatment of rheumatism, hepatitis, and pain. Four antifungal bisphosphocholines [irlbacholine (2) and three new analogues, gentianalines A-C (1, 3, and 4)] were identified from G. crassicaulis by a bioassay-guided fractionation and structure elucidation approach. Subsequent chemical analysis of 56 "Qinjiao" samples (45 from G. crassicaulis, five from G. macrophylla, three from G. dahurica, and three from G. straminea) showed that bisphosphocholines were present in all four Gentiana species, with irlbacholine as the major compound ranging from 2.0 to 6.2 mg per gram of dried material. Irlbacholine exhibited potent in vitro antifungal activity against Cryptococcus neoformans, Aspergillus fumigatus, Candida albicans, and Candida glabrata with minimum inhibitory concentration (MIC) values of 0.63, 1.25, 10.0, and 5.0 μg/mL, respectively. Identification of the bisphosphocholines, a rare class of antifungal natural products, in these medicinal plants provides scientific evidence to complement their medicinal use. The bisphosphocholines carrying a long aliphatic chain possess amphiphilic molecule-like properties with a tendency of retention in both normal and reversed-phase silica gel column chromatography and thereby may be neglected in natural products discovery. This report may stimulate interest in this class of compounds, which warrant the further study of other biological activities as well.

Impact of clinically acquired miltefosine resistance by Leishmania infantum on mouse and sand fly infection

Objectives

This study evaluated the implications of clinically acquired miltefosine resistance (MIL-R) by assessing virulence in mice and sand flies to reveal the potential of MIL-R strains to circulate.

Methods

Experimental infections with the MIL-R clinical Leishmania infantum isolate MHOM/FR/2005/LEM5159, having a defect in the LiROS3 subunit of the MIL-transporter, and its syngeneic experimentally reconstituted MIL-S counterpart (LEM5159^LiROS3) were performed in BALB/c mice and Lutzomyia longipalpis and Phlebotomus perniciosus sand flies. In mice, the amastigote burdens in liver and spleen were compared microscopically using Giemsa smears and by bioluminescent imaging. During the sand fly infections, the percentage of infected flies, parasite load, colonization of the stomodeal valve and metacyclogenesis were evaluated. The stability of the MIL-R phenotype after sand fly and mouse passage was determined as well.

Results

The fitness of the MIL-R strain differed between the mouse and sand fly infection model. In mice, a clear fitness loss was observed compared to the LiROS3-reconstituted susceptible strain. This defect could be rescued by episomal reconstitution with a wildtype LiROS3 copy. However, this fitness loss was not apparent in the sand fly vector, resulting in metacyclogenesis and efficient colonization of the stomodeal valve. Resistance was stable after passage in both sand fly and mouse.

Conclusion

The natural MIL-R strain is significantly hampered in its ability to multiply and cause a typical visceral infection pattern in BALB/c mice. However, this LiROS3-deficient strain efficiently produced mature infections and metacyclic promastigotes in the sand fly vector highlighting the transmission potential of this particular MIL-R clinical Leishmania strain.

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A clinical MIL-R L. infantum strain displays a loss-of-fitness in the mammalian host.

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ROS3-deficiency is compatible with efficient transmission by two sand fly species.

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Resistance is stable after mouse and sand fly passage.

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Transmission of this clinical MIL-R strain is a risk for immunocompromised patients.

Bifunctional Phosphorylcholine-Modified Adsorbent with Enhanced Selectivity and Antibacterial Property for Recovering Uranium from Seawater

The recovery of uranium from seawater is of great concern because of the growing demand for nuclear energy. Though amidoxime-functionalized adsorbents as the most promising adsorbents have been widely used for this purpose, their low selectivity and vulnerability to biofouling have limited their application in real marine environments. Herein, a new bifunctional phosphorylcholine-modified adsorbent (PVC-PC) is disclosed. The PVC-PC fiber is found to be suitable for use in the pH range of seawater and metals that commonly coexist with uranium, such as alkali and alkaline earth metals, transition metals, and lanthanide metals, have no obvious effect on its uranium adsorption capacity. PVC-PC shows better selectivity and adsorption capacity than the commonly used amidoxime-functionalized adsorbent. Furthermore, PVC-PC fiber exhibits excellent antibacterial properties which could reduce the effects of biofouling caused by marine microorganisms. Because of its good selectivity and antibacterial property, phosphorylcholine-based material shows great potential as a new generation adsorbent for uranium recovery from seawater.

Comparison of in vitro Resistance of Wild Leishmania İsolates, Which are Resistant to Pentavalent Antimonial Compounds, Against Drugs Used in the Treatment of Leishmaniasis

OBJECTIVE

Meglumine antimoniate (Glucantime^®) and Sodium stibogluconate (Pentostam^®) are used for the treatment of cutaneous leismaniasis in Turkey. There is a reported resistance to these drugs in recent years. The aim of the present study was to compare the in vitro sensitivities of resistant Leishmania isolates against Amphotericin B, Miltefosine, Meglumine Antimoniate, Paromomycin and Sodium Stibogluconate.

METHODS

Five Leishmania isolates of patients with cutaneous leishmaniasis, who showed no clinical recovery despite two consecutive meglumine antimoniate treatments, which were stored in the Parasite Bank in Manisa Celal Bayar University Medical Faculty were selected. They were genotyped with Real-Time PCR using specific primers and probes to ITS1 region. Drug resistance levels of each Leishmania isolate were analysed for Amphotericin B, Miltefosine, Meglumine Antimoniate, Paromomycin, and Sodium Stibogluconate at concentrations of 500, 250, 125, 50, 25 μg/mL with XTT method and hemocytometer.

RESULTS

It was observed that the resistant Leishmania tropica isolates showed no resistance to Amphotericin B, and were sensitive to Miltefosine, Sodium Stibogluconate, Paromomycin and Meglumin Antimonate, respectively. In addition, Leishmania tropica (MHOM/AZ/1974/SAF-K27) isolate of the control group could stay viable in none of the drug concentrations of five agents in the study.

CONCLUSION

It was determined that none of the selected resistant L. tropica isolates showed resistance to Amphotericin B and that was also shown statistically (p<0.05). The results of this study are important in guiding clinicians and researchers who conduct studies on drugs and search for new drug molecules.

Synergistic action of doxorubicin and 7-Ethyl-10-hydroxycamptothecin polyphosphorylcholine polymer prodrug

There are opportunities for improvements to the efficiency and toxicity of widely used cancer chemotherapy agents such as doxorubicin (DOX·HCl) and 7-Ethyl-10-hydroxycamptothecin (SN38). We developed a safe and effective combination therapy by encapsulating DOX into micelles of a zwitterionic polymer prodrug, SN38 conjugate of poly (α-azide caprolactone-co-caprolactone)-b-poly (2-methacryloyloxyethyl phosphorylcholine [P(CL/CL-g-SN38)-b-PMPC)] which was described in our previous work. The polymer prodrug micelles displayed a higher loading capacity of DOX due to the π-π stacking effect between DOX and SN38 in comparison with the micelles self-assembled by prodrug's precursor, poly(α-azide caprolactone-co-caprolactone)-b-poly(2-methacryloyloxyethyl phosphorylcholine (P(ACL/CL)-b-PMPC). The DOX loaded prodrug micelles decelerated the release of DOX, and also prolonged its circulation. The micelles showed favorable cellular internalization by 4T1 cells. DOX loaded SN38 prodrug micelles displayed good in vitro anticancer effects owing to the synergistic action of doxorubicin and SN38 and were as effective as DOX·HCl, but with lower toxicity than DOX·HCl. Given the synergetic effects of free drug and polymer prodrug, this nanomedicine may offer a safe and effective drug delivery methodology for conventional drug formations.

APOBEC3B reporter myeloma cell lines identify DNA damage response pathways leading to APOBEC3B expression

Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) DNA cytosine deaminase 3B (A3B) is a DNA editing enzyme which induces genomic DNA mutations in multiple myeloma and in various other cancers. APOBEC family proteins are highly homologous so it is especially difficult to investigate the biology of specifically A3B in cancer cells. To easily and comprehensively investigate A3B function in myeloma cells, we used CRISPR/Cas9 to generate A3B reporter cells that contain 3×FLAG tag and IRES-EGFP sequences integrated at the end of the A3B gene. These reporter cells stably express 3xFLAG tagged A3B and the reporter EGFP and this expression is enhanced by known stimuli, such as PMA. Conversely, shRNA knockdown of A3B decreased EGFP fluorescence and 3xFLAG tagged A3B protein levels. We screened a series of anticancer treatments using these cell lines and identified that most conventional therapies, such as antimetabolites or radiation, exacerbated endogenous A3B expression, but recent molecular targeted therapeutics, including bortezomib, lenalidomide and elotuzumab, did not. Furthermore, chemical inhibition of ATM, ATR and DNA-PK suppressed EGFP expression upon treatment with antimetabolites. These results suggest that DNA damage triggers A3B expression through ATM, ATR and DNA-PK signaling.

Structure based designing of benzimidazole/benzoxazole derivatives as anti-leishmanial agents

Folates are essential biomolecules required to carry out many crucial processes in leishmania parasite. Dihydrofolate reductase-thymidylate synthase (DHFR-TS) and pteridine reductase 1 (PTR1) involved in folate biosynthesis in leishmania have been established as suitable targets for development of chemotherapy against leishmaniasis. In the present study, various computational tools such as homology modelling, pharmacophore modelling, docking, molecular dynamics and molecular mechanics have been employed to design dual DHFR-TS and PTR1 inhibitors. Two designed molecules, i.e. 2-(4-((4-nitrobenzyl)oxy)phenyl)-1H-benzo[d]imidazole and 2-(4-((2,4-dichlorobenzyl)oxy)phenyl)-1H-benzo[d]oxazolemolecules were synthesized. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was performed to evaluate in vitro activity of molecules against promastigote form of Leishmania donovani using Miltefosine as standard. 2-(4-((4-nitrobenzyl)oxy)phenyl)-1H-benzo[d]imidazole and 2-(4-((2,4-dichlorobenzyl)oxy)phenyl)-1H-benzo[d]oxazolemolecules were found to be moderately active with showed IC₅₀ = 68 ± 2.8 µM and 57 ± 4.2 µM, respectively.

Bioinspired Surface Functionalization of Titanium Alloy for Enhanced Lubrication and Bacterial Resistance

In clinics it is extremely important for implanted devices to achieve the property of enhanced lubrication and bacterial resistance; however, such a strategy has rarely been reported in previous literature. In the present study, a surface functionalization method, motivated by articular cartilage-inspired superlubrication and mussel-inspired adhesion, was proposed to modify titanium alloy (Ti6Al4V) using the copolymer (DMA-MPC) synthesized via free radical copolymerization. The copolymer-coated Ti6Al4V (Ti6Al4V@DMA-MPC) was evaluated by X-ray photoelectron spectroscopy, water contact angle, and Raman spectra to confirm that the DMA-MPC copolymer was successfully coated onto the Ti6Al4V substrate. In addition, the tribological test, with the polystyrene microsphere and Ti6Al4V or Ti6Al4V@DMA-MPC as the tribopair, indicated that the friction coefficient was greatly reduced for Ti6Al4V@DMA-MPC. Furthermore, the bacterial resistance test showed that bacterial attachment was significantly inhibited for Ti6Al4V@DMA-MPC for the three types of bacteria tested. The enhanced lubrication and bacterial resistance of Ti6Al4V@DMA-MPC was due to the tenacious hydration shell formed surrounding the zwitterionic charges in the phosphorylcholine group of the DMA-MPC copolymer. In summary, a bioinspired surface functionalization strategy is developed in this study, which can act as a universal and promising method to achieve enhanced lubrication and bacterial resistance for biomedical implants.

Zwitterionic PMCP-Modified Polycaprolactone Surface for Tissue Engineering: Antifouling, Cell Adhesion Promotion, and Osteogenic Differentiation Properties

Biodegradable polycaprolactone (PCL) has been widely applied as a scaffold material in tissue engineering. However, the PCL surface is hydrophobic and adsorbs nonspecific proteins. Some traditional antifouling modifications using hydrophilic moieties have been successful but inhibit cell adhesion, which is not ideal for tissue engineering. The PCL surface is modified with bioinspired zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] (PMCP) via surface-initiated atom transfer radical polymerization to improve cell adhesion through the unique interaction between choline phosphate (CP, on PMCP) and phosphate choline (PC, on cell membranes). The hydrophilicity of the PCL surface is significantly enhanced after surface modification. The PCL-PMCP surface reduces nonspecific protein adsorption (e.g., up to 91.7% for bovine serum albumin) due to the zwitterionic property of PMCP. The adhesion and proliferation of bone marrow mesenchymal stem cells on the modified surface is remarkably improved, and osteogenic differentiation signs are detected, even without adding any osteogenesis-inducing supplements. Moreover, the PCL-PMCP films are more stable at the early stage of degradation. Therefore, the PMCP-functionalized PCL surface promotes cell adhesion and osteogenic differentiation, with an antifouling background, and exhibits great potential in tissue engineering.

Tailoring Biomimetic Phosphorylcholine-Containing Block Copolymers as Membrane-Targeting Cellular Rescue Agents

Some synthetic polymers can block cell death when applied following an injury that would otherwise kill the cell. This cellular rescue occurs through interactions of the polymers with cell membranes. However, general principles for designing synthetic polymers to ensure strong, but nondisruptive, cell membrane targeting are not fully elucidated. Here, we tailored biomimetic phosphorylcholine-containing block copolymers to interact with cell membranes and determined their efficacy in blocking neuronal death following oxygen-glucose deprivation. By adjusting the hydrophilicity and membrane affinity of poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC)-based triblock copolymers, the surface active regime in which the copolymers function effectively as membrane-targeting cellular rescue agents was determined. We identified nonintrusive interactions between the polymer and the cell membrane that alter the collective dynamics of the membrane by inducing rigidification without disrupting lipid packing or membrane thickness. In general, our results open new avenues for biological applications of polyMPC-based polymers and provide an approach to designing membrane-targeting agents to block cell death after injury.

Inhibitors of AKT kinase increase LDL receptor mRNA expression by two different mechanisms

Protein kinase B (AKT) is a serine/threonine kinase that functions as an important downstream effector of phosphoinositide 3-kinase. We have recently shown that MK-2206 and triciribine, two highly selective AKT inhibitors increase the level of low density lipoprotein receptor (LDLR) mRNA which leads to increased amount of cell-surface LDLRs. However, whereas MK-2206 induces transcription of the LDLR gene, triciribine stabilizes LDLR mRNA, raising the possibility that the two inhibitors may actually affect other kinases than AKT. In this study, we aimed to ascertain the role of AKT in regulation of LDLR mRNA expression by examining the effect of five additional AKT inhibitors on LDLR mRNA levels. Here we show that in cultured HepG2 cells, AKT inhibitors ARQ-092, AKT inhibitor VIII, perifosine, AT7867 and CCT128930 increase LDLR mRNA levels by inducing the activity of LDLR promoter. CCT128930 also increased the stability of LDLR mRNA. To study the role of AKT isoforms on LDLR mRNA levels, we examined the effect of siRNA-mediated knockdown of AKT1 or AKT2 on LDLR promoter activity and LDLR mRNA stability. Whereas knockdown of either AKT1 or AKT2 led to upregulation of LDLR promoter activity, only knockdown of AKT2 had a stabilizing effect on LDLR mRNA. Taken together, these results provide strong evidence for involvement of AKT in regulation of LDLR mRNA expression, and point towards the AKT isoform specificity for upregulation of LDLR mRNA expression.

Reductive Stress Selectively Disrupts Collagen Homeostasis and Modifies Growth Factor-independent Signaling Through the MAPK/Akt Pathway in Human Dermal Fibroblasts

Redox stress is a well-known contributor to aging and diseases in skin. Reductants such as dithiothreitol (DTT) can trigger a stress response by disrupting disulfide bonds. However, the quantitative response of the cellular proteome to reductants has not been explored, particularly in cells such as fibroblasts that produce extracellular matrix proteins. Here, we have used a robust, unbiased, label-free SWATH-MS proteomic approach to quantitate the response of skin fibroblast cells to DTT in the presence or absence of the growth factor PDGF. Of the 4487 proteins identified, only 42 proteins showed a statistically significant change of 2-fold or more with reductive stress. Our proteomics data show that reductive stress results in the loss of a small subset of reductant-sensitive proteins (including the collagens COL1A1/2 and COL3A1, and the myopathy-associated collagens COL6A1/2/3), and the down-regulation of targets downstream of the MAPK pathway. We show that a reducing environment alters signaling through the PDGF-associated MAPK/Akt pathways, inducing chronic dephosphorylation of ERK1/2 at Thr202/Tyr204 and phosphorylation of Akt at Ser473 in a growth factor-independent manner. Our data highlights collagens as sentinel molecules for redox stress downstream of MAPK/Akt, and identifies intervention points to modulate the redox environment to target skin diseases and conditions associated with erroneous matrix deposition.

A potential acetyltransferase involved in Leishmania major metacaspase-dependent cell death

BACKGROUND

Currently, there is no satisfactory treatment for leishmaniases, owing to the cost, mode of administration, side effects and to the increasing emergence of drug resistance. As a consequence, the proteins involved in Leishmania apoptosis seem a target of choice for the development of new therapeutic tools against these neglected tropical diseases. Indeed, Leishmania cell death, while phenotypically similar to mammalian apoptosis, is very peculiar, involving no homologue of the key mammalian apoptotic proteins such as caspases and death receptors. Furthermore, very few proteins involved in Leishmania apoptosis have been identified.

RESULTS

We identified a protein involved in Leishmania apoptosis from a library of genes overexpressed during Leishmania differentiation during which autophagy occurs. Indeed, the gene was overexpressed when L. major cell death was induced by curcumin or miltefosine. Furthermore, its overexpression increased L. major curcumin- and miltefosine-induced apoptosis. This gene, named LmjF.22.0600, whose expression is dependent on the expression of the metacaspase, another apoptotic protein, encodes a putative acetyltransferase.

CONCLUSIONS

This new protein, identified as being involved in Leishmania apoptosis, will contribute to a better understanding of Leishmania death, which is needed owing to the absence of a satisfactory treatment against leishmaniases. It will also allow a better understanding of the original apoptotic pathways of eukaryotes in general, while evidence of the existence of such pathways is accumulating.

A novel UCHL3 inhibitor, perifosine, enhances PARP inhibitor cytotoxicity through inhibition of homologous recombination-mediated DNA double strand break repair

Triple-negative breast cancer (TNBC) treatment remains a great challenge for clinical practice and novel therapeutic strategies are urgently needed. UCHL3 is a deubiquitinase that is overexpressed in TNBC and correlates with poor prognosis. UCHL3 deubiquitinates RAD51 thereby promoting the recruitment of RAD51 to DNA damage sites and augmenting DNA repair. Therefore, UCHL3 overexpression can render cancer cells resistant to DNA damage inducing chemo and radiotherapy, and targeting UCHL3 can sensitize TNBC to radiation and chemotherapy. However, small molecule inhibitors of UCHL3 are yet to be identified. Here we report that perifosine, a previously reported Akt inhibitor, can inhibit UCHL3 in vitro and in vivo. We found low dose (50 nM) perifosine inhibited UCHL3 deubiquitination activity without affecting Akt activity. Furthermore, perifosine enhanced Olaparib-induced growth inhibition in TNBC cells. Mechanistically, perifosine induced RAD51 ubiquitination and blocked the RAD51-BRCA2 interaction, which in turn decreased ionizing radiation-induced foci (IRIF) of Rad51 and, thereby, homologous recombination (HR)-mediated DNA double strand break repair. In addition, combination of perifosine and Olaparib showed synergistic antitumor activity in vivo in TNBC xenograft model. Thus, our present study provides a novel therapeutic approach to optimize PARP inhibitor treatment efficiency.

(De)glutamylation and cell death in Leishmania parasites

Trypanosomatids are flagellated protozoan parasites that are very unusual in terms of cytoskeleton organization but also in terms of cell death. Most of the Trypanosomatid cytoskeleton consists of microtubules, forming different substructures including a subpellicular corset. Oddly, the actin network appears structurally and functionally different from other eukaryotic actins. And Trypanosomatids have an apoptotic phenotype under cell death conditions, but the pathways involved are devoid of key mammal proteins such as caspases or death receptors, and the triggers involved in apoptotic induction remain unknown. In this article, we have studied the role of the post-translational modifications, deglutamylation and polyglutamylation, in Leishmania. We have shown that Leishmania apoptosis was linked to polyglutamylation and hypothesized that the cell survival process autophagy was linked to deglutamylation. A balance seems to be established between polyglutamylation and deglutamylation, with imbalance inducing microtubule or other protein modifications characterizing either cell death if polyglutamylation was prioritized, or the cell survival process of autophagy if deglutamylation was prioritized. This emphasizes the role of post-translational modifications in cell biology, inducing cell death or cell survival of infectious agents.

Leishmania are unique unicellular organisms in terms of cytoskeleton organization and mechanisms of cell death. For example, the major cytoskeletal components of these parasites are microtubules, which form a subpellicular corset. In terms of cell death, an apoptotic phenotype has been characterized in Leishmania but the pathways remain unknown, being devoid of key mammal cell death proteins. In a previous article, we demonstrated that the cytoskeleton of this parasite is extensively glutamylated but, paradoxically, overexpression or inhibition of polyglutamylase expression have limited visible cellular consequences. In this manuscript, we have highlighted the link between polyglutamylation and Leishmania cell death, suggesting the importance of the polyglutamylation/deglutamylation balance in this parasite. Further, we have identified, for the first time in Leishmania, deglutamylases, among which one that, in an original manner, deglutamylates glutamates at branching points but also long glutamate side chains. This work emphasizes the role of post-translational modifications as essential regulators of protein function, not only of mammal cells such as neurons or ciliated/flagellated cells, but also of infectious agents. This work suggests an important and discernible “live or die”—“cell death or autophagy” balance pathway and the conceptual mechanism that is involved in cellular decision making.

Helminth-Related Tuftsin-Phosphorylcholine Compound and its Interplay with Autoimmune Diseases

The hygiene theory represents one of the environmental facets that modulate the risk for developing autoimmune diseases. There is a reverse correlation between the presence of helminthes and flares of autoimmune diseases, which explains the rise in incidence of certain autoimmune diseases in developed countries. The protective properties of certain helminthes are attributed to their secretory compounds which immunomodulate the host immune network in order to survive. Thus, the helminthes use an array of mechanisms. One of the major mechanisms enabling manipulation of the host-helminth interaction is by targeting the pattern recognition receptors (PRRs)-dependent and -independent mechanisms, which include toll-like receptors, C-type lectin receptors, and the inflammasome. The current review provides a glimpse of numerous helminth secreted products which have a role in the immunomodulation of the host immune network, focusing on bifunctional tuftsin-phosphorylcholine (TPC). TPC is a natural compound based on phosphorylcholine of helminth origin that was used in the past to cover stents and tuftsin, a self-peptide derived from the spleen. TPC was proven to be efficient in three murine experimental models (lupus, colitis, and arthritis) and ex vivo in giant cell arteritis.

A chronic bioluminescent model of experimental visceral leishmaniasis for accelerating drug discovery

Background

Visceral leishmaniasis is a neglected parasitic disease with no vaccine available and its pharmacological treatment is reduced to a limited number of unsafe drugs. The scarce readiness of new antileishmanial drugs is even more alarming when relapses appear or the occurrence of hard-to-treat resistant strains is detected. In addition, there is a gap between the initial and late stages of drug development, which greatly delays the selection of leads for subsequent studies.

Methodology/Principal findings

In order to address these issues, we have generated a red-shifted luminescent Leishmania infantum strain that enables long-term monitoring of parasite burden in individual animals with an in vivo limit of detection of 10⁶ intracellular amastigotes 48 h postinfection. For this purpose, we have injected intravenously different infective doses (10⁴—5x10⁸) of metacyclic parasites in susceptible mouse models and the disease was monitored from initial times to 21 weeks postinfection. The emission of light from the target organs demonstrated the sequential parasite colonization of liver, spleen and bone marrow. When miltefosine was used as proof-of-concept, spleen weight parasite burden and bioluminescence values decreased significantly.

Conclusions

In vivo bioimaging using a red-shifted modified Leishmania infantum strain allows the appraisal of acute and chronic stage of infection, being a powerful tool for accelerating drug development against visceral leishmaniasis during both stages and helping to bridge the gap between early discovery process and subsequent drug development.

Visceral leishmaniasis is a neglected disease that poses a significant threat to impoverished human populations of low-income countries. Due to the unavailability of vaccines, pharmacological treatment is the only approach to control the disease that otherwise can be lethal. To date, drug management in endemic regions is based on combinations of a handful of mostly unsafe drugs, where the emergence of resistant strains is an additional problem. To accelerate the discovery of new drug entities, several gaps from the early discovery of a compound to its public use, should be filled. One of these gaps is the need of a rapid go/no-go testing system for compounds based on robust preclinical models. Here, we propose a new long-term model of murine visceral leishmaniasis using in vivo bioluminescent imaging. For this purpose, a red-shifted bioluminescent Leishmania infantum strain was engineered. This strain has allowed the appraisal of the disease in individual animals and the monitoring of parasite colonization in liver, spleen and bone marrow. As proof of concept of this platform, mice were infected with the transgenic L. infantum strain treated with a standard schedule of miltefosine, the only oral drug available against Leishmania parasites. Bioluminescence and parasite load in the target organs were compared showing a good correlation. Our findings provide a robust and reproducible tool for drug discovery in a chronic model of murine visceral leishmaniasis.

Cell-Membrane-Inspired Silicone Interfaces that Mitigate Proinflammatory Macrophage Activation and Bacterial Adhesion

Biofouling on silicone implants causes serious complications such as fibrotic encapsulation, bacterial infection, and implant failure. Here we report the development of antifouling, antibacterial silicones through covalent grafting with a cell-membrane-inspired zwitterionic gel layer composed of 2-methacryolyl phosphorylcholine (MPC). To investigate how substrate properties influence cell adhesion, we cultured human-blood-derived macrophages and Escherichia coli on poly(dimethylsiloxane) (PDMS) and MPC gel surfaces with a range of 0.5-50 kPa in stiffness. Cells attach to glass, tissue culture polystyrene, and PDMS surfaces, but they fail to form stable adhesions on MPC gel surfaces due to their superhydrophilicity and resistance to biofouling. Cytokine secretion assays confirm that MPC gels have a much lower potential to trigger proinflammatory macrophage activation than PDMS. Finally, modification of the PDMS surface with a long-term stable hydrogel layer was achieved by the surface-initiated atom-transfer radical polymerization (SI-ATRP) of MPC and confirmed by the decrease in contact angle from 110 to 20° and the >70% decrease in the attachment of macrophages and bacteria. This study provides new insights into the design of antifouling and antibacterial interfaces to improve the long-term biocompatibility of medical implants.

Efficacy of Apigenin and Miltefosine Combination Therapy against Experimental Cutaneous Leishmaniasis

Leishmaniasis is a neglected tropical disease caused by several different species of Leishmania. Treatment of leishmaniasis involves a limited drug arsenal that is associated with severe side effects, high costs, and drug resistance. Therefore, combination therapy has emerged as a strategy to improve leishmaniasis treatment. Here, we report the interaction of miltefosine and apigenin in vitro and in vivo. Combination therapy using low doses of these two drugs results in good clinical and parasitological responses.

Selective laser melted titanium alloys for hip implant applications: Surface modification with new method of polymer grafting

A significant number of hip replacements (HR) fail permanently despite the success of the medical procedure, due to wear and progressive loss of osseointegration of implants. An ideal model should consist of materials with a high resistance to wear and with good biocompatibility. This study aims to develop a new method of grafting the surface of selective laser melted (SLM) titanium alloy (Ti-6Al-4V) with poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), to improve the surface properties and biocompatibility of the implant. PMPC was grafted onto the SLM fabricated Ti-6Al-4V, applying the following three techniques; ultraviolet (UV) irradiation, thermal heating both under normal atmosphere and UV irradiation under N₂ gas atmosphere. Scanning electron microscopy (SEM), 3D optical profiler, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) were used to characterise the grafted surface. Results demonstrated that a continuous PMPC layer on the Ti-6Al-4V surface was achieved using the UV irradiation under N₂ gas atmosphere technique, due to the elimination of oxygen from the system. As indicated in the results, one of the advantages of this technique is the presence of phosphorylcholine, mostly on the surface, which reveals the existence of a strong chemical bond between the grafted layer (PMPC) and substrate (Ti-6Al-4V). The nano-scratch test revealed that the PMPC grafted surface improves the mechanical strength of the surface and thus, protects the underlying implant substrate from scratching under high loads.

Effects of water-aging for 6 months on the durability of a novel antimicrobial and protein-repellent dental bonding agent

Biofilms at the tooth-restoration bonded interface can produce acids and cause recurrent caries. Recurrent caries is a primary reason for restoration failures. The objectives of this study were to synthesize a novel bioactive dental bonding agent containing dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) to inhibit biofilm formation at the tooth-restoration margin and to investigate the effects of water-aging for 6 months on the dentin bond strength and protein-repellent and antibacterial durability. A protein-repellent agent (MPC) and antibacterial agent (DMAHDM) were added to a Scotchbond multi-purpose (SBMP) primer and adhesive. Specimens were stored in water at 37 °C for 1, 30, 90, or 180 days (d). At the end of each time period, the dentin bond strength and protein-repellent and antibacterial properties were evaluated. Protein attachment onto resin specimens was measured by the micro-bicinchoninic acid approach. A dental plaque microcosm biofilm model was used to test the biofilm response. The SBMP + MPC + DMAHDM group showed no decline in dentin bond strength after water-aging for 6 months, which was significantly higher than that of the control (P < 0.05). The SBMP + MPC + DMAHDM group had protein adhesion that was only 1/20 of that of the SBMP control (P < 0.05). Incorporation of MPC and DMAHDM into SBMP provided a synergistic effect on biofilm reduction. The antibacterial effect and resistance to protein adsorption exhibited no decrease from 1 to 180 d (P > 0.1). In conclusion, a bonding agent with MPC and DMAHDM achieved a durable dentin bond strength and long-term resistance to proteins and oral bacteria. The novel dental bonding agent is promising for applications in preventive and restorative dentistry to reduce biofilm formation at the tooth-restoration margin.

Complex Interplay between Sphingolipid and Sterol Metabolism Revealed by Perturbations to the Leishmania Metabolome Caused by Miltefosine

With the World Health Organization reporting over 30,000 deaths and 200,000 to 400,000 new cases annually, visceral leishmaniasis is a serious disease affecting some of the world's poorest people. As drug resistance continues to rise, there is a huge unmet need to improve treatment. Miltefosine remains one of the main treatments for leishmaniasis, yet its mode of action (MoA) is still unknown. Understanding the MoA of this drug and parasite response to treatment could help pave the way for new and more successful treatments for leishmaniasis. A novel method has been devised to study the metabolome and lipidome of Leishmania donovani axenic amastigotes treated with miltefosine. Miltefosine caused a dramatic decrease in many membrane phospholipids (PLs), in addition to amino acid pools, while sphingolipids (SLs) and sterols increased. Leishmania major promastigotes devoid of SL biosynthesis through loss of the serine palmitoyl transferase gene (ΔLCB2) were 3-fold less sensitive to miltefosine than wild-type (WT) parasites. Changes in the metabolome and lipidome of miltefosine-treated L. major mirrored those of L. donovani A lack of SLs in the ΔLCB2 mutant was matched by substantial alterations in sterol content. Together, these data indicate that SLs and ergosterol are important for miltefosine sensitivity and, perhaps, MoA.

Chemotherapeutics of visceral leishmaniasis: present and future developments

Treatment of Visceral Leishmaniasis (VL), a neglected tropical disease, is very challenging with few treatment options. Long duration of treatment and drug toxicity further limit the target of achieving VL elimination. Chemotherapy remains the treatment of choice. Single dose of liposomal amphotericin B (LAmB) and multidrug therapy (LAmB + miltefosine, LAmB + paromomycin (PM), or miltefosine + PM) are recommended treatment regimen for treatment of VL in Indian sub-continent. Combination therapy of pentavalent antimonials (Sbv) and PM in East Africa and LAmB in the Mediterranean region/South America remains the treatment of choice. Various drugs having anti-leishmania properties are in preclinical phase and need further development. An effective treatment and secondary prophylaxis of HIV-VL co-infection should be developed to decrease treatment failure and drug resistance.