Nisin inducible production of listeriolysin O in Lactococcus lactis NZ9000

<p>Abstract</p> <p>Background</p> <p><it>Listeria monocytogenes </it>is a well-characterized food-borne pathogen that infects pregnant women and immunocompromised individuals. Listeriolysin O (LLO) is the major virulence factor of the pathogen and is often used as a diagnostic marker for detection of <it>L. monocytogenes</it>. In addition, LLO represents a potent antigen driving T cell-mediated immunity during infection. In the present work, <it>Lactococcus lactis </it>NZ9000 was used as an expression host to hyper-produce LLO under inducible conditions using the NICE (NIsin Controlled Expression) system. We created a modified pNZ8048 vector encoding a six-His-tagged LLO downstream of the strong inducible PnisA promoter.</p> <p>Results</p> <p>The constructed vector (pNZPnisA:CYTO-LLO) was expressed in <it>L. lactis </it>NZ9000 and was best induced at mid-log phase with 0.2% v/v nisin for 4 h statically at 30°C. Purification of the His-tagged LLO was accomplished by Ni-NTA affinity chromatography and functionality was confirmed through haemolytic assays. Total LLO yield (measured as total protein content) was 4.43–5.9 mg per litre culture and the haemolytic activity was still detectable after 8 months of storage at 4°C.</p> <p>Conclusion</p> <p>The LLO production method described in this work provides an approach to efficient LLO production in the Gram-positive <it>Lactococcus </it>bacterium to yield a significant source of the protein for research and diagnostic applications. Expression of LLO in <it>L. lactis </it>has a number of benefits over <it>E. coli </it>which may facilitate both <it>in vivo </it>and <it>in vitro </it>applications of this system.</p

Targeted DPPC/DMPG surface-modified voriconazole lipid nanoparticles control invasive pulmonary aspergillosis in immunocompromised population: in-vitro and in-vivo assessment

Invasive pulmonary aspergillosis (IPA) is the most devastating Aspergillus-related lung disease. Voriconazole (VRZ) is the first-line treatment against IPA. Despite availability in oral and parenteral dosage forms, risks of systemic toxicity dictate alternative pulmonary administration. Inspired by natural lung surfactants, dipalmitoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DPPC/DMPG) surface-modified lipid nanoparticles (LNPs) were scrutinized for pulmonary administration. DPPC/DMPG-VRZ-LNPs prepared using ultrasonication/thin film hydration were investigated for colloidal properties over 3-month shelf storage. They were stable with a slight change in entrapment efficiency. They provided a sustained VRZ release over 24 h, with a rapid initial release. In vitro aerosolization indicated higher percentages of VRZ deposited on stages corresponding to secondary bronchi and alveolar ducts. Moreover, intrapulmonary administration maintained high lung VRZ concentration (27 ± 1.14 µg/g) after 6 h. A preclinical study using a cyclophosphamide-induced neutropenic rat model demonstrated a 3-fold reduction in BALF-Galactomannan down to 0.515 ± 0.22 µg/L confirming DPPC/DMPG-VRZ-LNPs potential in hyphal growth inhibition. Histopathological examination of infected/nontreated lung sections exhibited dense fungal load inside alveoli and blood vessels indicating massive tissue and angio-invasiveness. Nevertheless, DPPC/DMPG-VRZ-LNPs-treated animals displayed minimal hyphae with no signs of invasiveness. The developed bioinspired nanoparticles serve as prospective bioactive nanocarrier candidates for pulmonary administration of VRZ in the management of IPA

Enhanced transdermal permeability of Terbinafine through novel nanoemulgel formulation; Development, in vitro and in vivo characterization

Terbinafine Hcl (TB) is a poorly water soluble antifungal drug. Topical nanoemulsion based gel containing TB was prepared with a view to improve its solubility and antifungal activity. In preparation of the nanoemulsion (NE), excipients were selected based on the solubility study. Peceol was optimized as the oil phase. Tween 80 and propanol were optimized as the surfactant and co-solvent respectively, and were mixed (Smix) in different weight ratios (1:1, 1:2, 1:3, 1:4, 4:1, 3:1 and 2:1, respectively). Pseudoternary phase diagrams were developed and Pecol and Smix were mixed in different weight ratios ranging from 1:9 to 9:1. Based on the NE region of each diagram, the formulae were selected. The formulated nanoemulsions were characterized and evaluated for in vitro drug release and thermodynamic stability. The optimum nanoemulsion formulae containing 10 or 15% w/w oil, 45% w/w Smix (1:2/1:3) and 45-40% w/w aqueous phase) were incorporated into Carbopol 940 gel bases forming three different TB nanoemulsion based emulgel formulae (F1-F3) which were examined for ex vivo drug permeation and in vivo antifungal activity compared to the marketed product; Lamisil® emulgel. The results showed that TB skin permeation from all the prepared nanoemulsion based gel formulae was significantly (p < 0.05) improved in relation to the commercial emulgel. F3 exhibited a superior in vivo antifungal activity over the marketed emulgel for the treatment of Candida infection. Keywords: Terbinafine nanoemulsion, Pseudoternary phase diagrams, Permeation stud

Iron Acquisition Proteins of <i>Pseudomonas aeruginosa</i> as Potential Vaccine Targets: In Silico Analysis and In Vivo Evaluation of Protective Efficacy of the Hemophore HasAp

Background: Pseudomonas aeruginosa (PA) is a Gram-negative pathogen responsible for fatal nosocomial infections worldwide. Iron is essential for Gram-negative bacteria to establish an infection. Therefore, iron acquisition proteins (IAPs) of bacteria are attractive vaccine targets. Methodology: A “Reverse Vaccinology” approach was employed in the current study. Expression levels of 37 IAPs in various types of PA infections were analyzed in seven previously published studies. The IAP vaccine candidate was selected based on multiple criteria, including a high level of expression, high antigenicity, solubility, and conservation among PA strains, utilizing suitable bioinformatics analysis tools. The selected IAP candidate was recombinantly expressed in Escherichia coli and purified using metal affinity chromatography. It was further evaluated in vivo for protection efficacy. The novel immune adjuvant, naloxone (NAL), was used. Results and discussion: HasAp antigen met all the in silico selection criteria, being highly antigenic, soluble, and conserved. In addition, it was the most highly expressed IAP in terms of average fold change compared to control. Although HasAp did excel in the in silico evaluation, subcutaneous immunization with recombinant HasAp alone or recombinant HasAp plus NAL (HasAP-NAL) did not provide the expected protection compared to controls. Immunized mice showed a low IgG2a/IgG1 ratio, indicating a T-helper type 2 (Th2)-oriented immune response that is suboptimal for protection against PA infections. Surprisingly, the bacterial count in livers of both NAL- and HasAp-NAL-immunized mice was significantly lower than the count in the HasAp and saline groups. The same trend was observed in kidneys and lungs obtained from these groups, although the difference was not significant. Such protection could be attributed to the enhancement of innate immunity by NAL. Conclusions: We provided a detailed in silico analysis of IAPs of PA followed by in vivo evaluation of the best IAP, HasAp. Despite the promising in silico results, HasAp did not provide the anticipated vaccine efficacy. HasAp should be further evaluated as a vaccine candidate through varying the immunization regimens, models of infection, and immunoadjuvants. Combination with other IAPs might also improve vaccination efficacy. We also shed light on several highly expressed promising IAPs whose efficacy as vaccine candidates is worthy of further investigation

Bacterial Ghosts of <i>Pseudomonas aeruginosa</i> as a Promising Candidate Vaccine and Its Application in Diabetic Rats

Infections with Pseudomonas aeruginosa (PA) pose a major clinical threat worldwide especially to immunocompromised patients. As a novel vaccine network for many kinds of bacteria, bacterial ghosts (BGs) have recently been introduced. In the present research, using Sponge-Like Reduced Protocol, P. aeruginosa ghosts (PAGs) were prepared to maintain surface antigens and immunogenicity. This is the first study, to our knowledge, on the production of chemically induced well-structured bacterial ghosts for PA using concentrations of different chemicals. The research was carried out using diabetic rats who were orally immunized at two-week intervals with three doses of PAGs. Rats were subsequently challenged either by the oral route or by the model of ulcer infection with PA. In challenged rats, in addition to other immunological parameters, organ bioburden and wound healing were determined, respectively. Examination of the scanning and transmission electron microscope (EM) proved that PAGs with a proper three-dimensional structure were obtained. In contrast to control groups, oral PAGs promoted the generation of agglutinating antibodies, the development of IFN-γ, and the increase in phagocytic activity in vaccinated groups. Antibodies of the elicited PAGs were reactive to PA proteins and lipopolysaccharides. The defense against the PA challenge was observed in PAGs-immunized diabetic rats. The resulting PAGs in orally vaccinated diabetic rats were able to evoke unique humoral and cell-mediated immune responses and to defend them from the threat of skin wound infection. These results have positive implications for future studies on the PA vaccine

Vancomycin-functionalized Eudragit-based nanofibers: Tunable drug release and wound healing efficacy

There is an unmet demand for local vancomycin (VAN) delivery scaffolds with site retention and tunable release properties for cutaneous and surgical wounds. Nanofibers as drug delivery/cell regeneration promoting scaffolds offer great promise in this respect. High loading of the polar VAN into polymeric structures with tunable release properties can be achieved by simultaneous chemical bonding and polymer blending. Electrospinnable vancomycin-functionalized Eudragit E100 with a relatively high drug content and antibacterial activity (E-VAN) was investigated for the development of antimicrobial nanofibers with modifiable hydrophilicity, degradability, mechanical and release properties by blending with selected Eudragit polymers. A platform of fast dissolving nanofibers of value in immediate release applications and nanofibers with a wide spectrum of biphasic release profiles with either fast or sustained drug release at low, high and physiological pH for at least 7 days was generated. A selected nanofiber formulation with a relatively small size, adequate hydrophilicity, structural stability, and biphasic release profile at pH 7.4 showed high antibacterial activity against Staphylococcus aureus and healing efficacy of Staphylococcus aureus-inoculated full thickness excision wounds in a rat model. The E-VAN-based Eudragit nanofibers developed offer potential as versatile antimicrobial delivery/cell regeneration scaffolds for local applications under diverse pH conditions

Combining hydrophilic chemotherapy and hydrophobic phytotherapy via tumor-targeted albumin–QDs nano-hybrids: covalent coupling and phospholipid complexation approaches

Abstract Background The rationale of this study is to combine the merits of both albumin nanoparticles and quantum dots (QDs) in improved drug tumor accumulation and strong fluorescence imaging capability into one carrier. However, premature drug release from protein nanoparticles and high toxicity of QDs due to heavy metal leakage are among challenging hurdles. Following this platform, we developed cancer nano-theranostics by coupling biocompatible albumin backbone to CdTe QDs and mannose moieties to enhance tumor targeting and reduce QDs toxicity. The chemotherapeutic water soluble drug pemetrexed (PMT) was conjugated via tumor-cleavable bond to the albumin backbone for tumor site-specific release. In combination, the herbal hydrophobic drug resveratrol (RSV) was preformulated as phospholipid complex which enabled its physical encapsulation into albumin nanoparticles. Results Albumin–QDs theranostics showed enhanced cytotoxicity and internalization into breast cancer cells that could be traced by virtue of their high fluorescence quantum yield and excellent imaging capacity. In vivo, the nanocarriers demonstrated superior anti-tumor effects including reduced tumor volume, increased apoptosis, and inhibited angiogenesis in addition to non-immunogenic response. Moreover, in vivo bioimaging test demonstrated excellent tumor-specific accumulation of targeted nanocarriers via QDs-mediated fluorescence. Conclusion Mannose-grafted strategy and QD-fluorescence capability were beneficial to deliver albumin nanocarriers to tumor tissues and then to release the anticancer drugs for killing cancer cells as well as enabling tumor imaging facility. Overall, we believe albumin–QDs nanoplatform could be a potential nano-theranostic for bioimaging and targeted breast cancer therapy