•The article provides a summary on cellular receptors involved in virus immunity.•It summarizes key findings on viroporins, a novel class of viral proteins and their role in the virus life cycle and ...host cell interactions.•It presents an overview of the current understanding of inflammasomes complex activation, with special focus on NLRP3.•It discusses the correlation between viroporins and inflammasomes activation and aggravated inflammatory cytokines production.
Viroporins are virus encoded proteins that alter membrane permeability and can trigger subsequent cellular signals. Oligomerization of viroporin subunits results in formation of a hydrophilic pore which facilitates ion transport across host cell membranes. These viral channel proteins may be involved in different stages of the virus infection cycle. Inflammasomes are large multimolecular complexes best recognized for their ability to control activation of caspase-1, which in turn regulates the maturation of interleukin-1 β (IL-1β) and interleukin 18 (IL-18). IL-1β was originally identified as a pro-inflammatory cytokine able to induce both local and systemic inflammation and a febrile reaction in response to infection or injury. Excessive production of IL-1β is associated with autoimmune and inflammatory diseases. Microbial derivatives, bacterial pore-forming toxins, extracellular ATP and other pathogen-associated molecular patterns trigger activation of NLRP3 inflammasomes. Recent studies have reported that viroporin activity is capable of inducing inflammasome activity and production of IL-1β, where NLRP3 is shown to be regulated by fluxes of K+, H+ and Ca2+ in addition to reactive oxygen species, autophagy and endoplasmic reticulum stress. The aim of this review is to present an overview of the key findings on viroporin activity with special emphasis on their role in virus immunity and as possible activators of inflammasomes.
Aims: To study the interactions between Candida albicans and 12 other species of Candida and bacteria in biofilms.
Methods and Results: The number of cells within growing biofilms in a polystyrene ...tube model was measured after adding C. albicans to preformed biofilms of other micro‐organisms and vice versa. It was also measured after simultaneous biofilm formation of C. albicans and other micro‐organisms. The number of cells of C. albicans within the growing biofilms decreased significantly (P < 0·05) when the fungus was added to preformed biofilms of Candida spp. and bacteria except, with C. parapsilosis, Torulopsis glabrata and the glycocalyx producer Pseudomonas aeruginosa. When C. parapsilosis, Staphylococcus epidermidis (nonglycocalyx producer) or Serratia marcescens was added to preformed biofilms of C. albicans, the number of cells of these micro‐organisms increased in the growing biofilms.
Conclusions: Biofilms of C. albicans are capable of holding other micro‐organisms and more likely to be heterogeneous with other bacteria and fungi in the environment and on medical devices.
Significance and Impact of the Study: Recognition of the heterogeneity of biofilm‐associated organisms can influence treatment decisions, particularly in patients who do not respond to initial appropriate therapy.
Silver nanoparticles (AgNPs) have been used as potential antimicrobial agents against resistant pathogens. We investigated the possible therapeutic use of AgNPs in combination with visible blue light ...against a multidrug resistant clinical isolate of Pseudomonas aeruginosa in vitro and in vivo. The antibacterial activity of AgNPs against P. aeruginosa (1×10(5) colony forming unit/mL) was investigated at its minimal inhibitory concentration (MIC) and sub-MIC, alone and in combination with blue light at 460 nm and 250 mW for 2 hours. The effect of this combined therapy on the treated bacteria was then visualized using transmission electron microscope. The therapy was also assessed in the prevention of biofilm formation by P. aeruginosa on AgNP-impregnated gelatin biopolymer discs. Further, in vivo investigations were performed to evaluate the efficacy of the combined therapy to prevent burn-wound colonization and sepsis in mice and, finally, to treat a real infected horse with antibiotic-unresponsive chronic wound. The antimicrobial activity of AgNPs and visible blue light was significantly enhanced (P<0.001) when both agents were combined compared to each agent alone when AgNPs were tested at MIC, 1/2, or 1/4 MIC. Transmission electron microscope showed significant damage to the cells that were treated with the combined therapy compared to other cells that received either the AgNPs or blue light. In addition, the combined treatment significantly (P<0.001) inhibited biofilm formation by P. aeruginosa on gelatin discs compared to each agent individually. Finally, the combined therapy effectively treated a horse suffering from a chronic wound caused by mixed infection, where signs of improvement were observed after 1 week, and the wound completely healed after 4 weeks. To our knowledge, this combinatorial therapy has not been investigated before. It was proved efficient and promising in managing infections caused by multidrug resistant bacteria and could be used as an alternative to conventional antibiotic therapy.
Hepatitis C is one of the most widespread infectious diseases worldwide and hepatitis C virus (HCV)-induced chronic inflammation is highly associated with progredient liver damage. It was shown that ...HCV infection increases levels of pro-inflammatory cytokines via activation of NOD-like receptor (NLRP3) inflammasomes, yet the underlying mechanism is still under question. We propose modulation of intracellular pH by p7, a 63 residue ion channel produced by the hepatitis C virus as a possible pathomechanism for hepatitis C-associated inflammation. Recombinant constructs corresponding to HCV genotypes 1–4 were expressed in HEK 293 and RAW 264.7 cells and changes of intracellular pH were monitored using pH-sensitive fluorescent probes as well as production of inflammatory cytokines. Presence of p7 induced general loss of vesicular acidity as well as producing a significant increase in the levels of interleukin-1β (IL-1β). Effects showed a genotype-dependent pattern of IL-1β production, in agreement with the pH-response profile of p7 channels corresponding to hepatitis C genotypes. Lowering the pH of the extracellular medium increased activity of p7 channels as well as production of IL-1β for genotypes 1, 3, and 4, but less for genotype 2. Our data are in agreement with the hypothesis that p7 activity can trigger intracellular signaling cascades that are involved in HCV-associated cytopathy.
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•p7 channels corresponding to genoptypes 1–4 were tested using patch-clamp methods.•Intracellular pH was monitored using pH-sensitive fluorescent dyes.•P7 is an intracellular proton-gated H+-channel.•P7 activity induced production of interleukin IL-1beta in liver macrophages.•Shunting of intracellular pH may trigger inflammatory responses in hepatitis C.
(1) Background: Hyaluronic acid (HA) is a polyanionic mucopolysaccharide extensively used in biomedical and cosmetic industries due to its unique rheological properties. Recombinant HA production ...using other microbial platforms has received increasing interest to avoid potential toxin contamination associated with its production by streptococcal fermentation. In this study, the Gram-negative strains Escherichia coli (pLysY/Iq), E. coli Rosetta2, E. coli Rosetta (DE3) pLysS, E. coli Rosetta2 (DE3), E. coli Rosetta gammiB(DE3)pLysS, and the Gram-positive Bacillus megaterium (MS941) were investigated as new platforms for the heterologous production of HA. (2) Results: The HA biosynthesis gene hasA, cloned from Streptococcus equi subsp. zoopedemicus, was ligated into plasmid pMM1522 (MoBiTec), resulting in pMM1522 hasA, which was introduced into E. coli Rosetta-2(DE3) and B. megaterium (MS941). The initial HA titer by the two hosts in the LB medium was 5 mg/L and 50 mg/L, respectively. Streptococcal hasABC and hasABCDE genes were ligated into plasmid pPT7 (MoBiTec) and different E. coli host strains were then transformed with the resulting plasmids pPT7hasABC and pPT7hasABCDE. For E. coli Rosetta-gamiB(DE3)pLysS transformed with pPT7hasABC, HA production was 500 ± 11.4 mg/L in terrific broth (TB) medium. Productivity was slightly higher (585 ± 2.9 mg/L) when the same host was transformed with pPT7 carrying the entire HA operon. We also transformed B. megaterium (MS941) protoplasts carrying T7-RNAP with pPT7hasABC and pPT7hasABCDE. In comparison, the former plasmid resulted in HA titers of 2116.7 ± 44 and 1988.3 ± 19.6 mg/L in LB media supplemented with 5% sucrose and A5 medium + MOPSO, respectively; the latter plasmid boosted the titer final concentration further to reach 2476.7 ± 14.5 mg/L and 2350 ± 28.8 mg/L in the two media, respectively. The molecular mass of representative HA samples ranged from 105 − 106 Daltons (Da), and the polydispersity index (PDI) was <2. Fourier transform infrared spectroscopy (FTIR) spectra of the HA product were identical to those obtained for commercially available standard polymers. Finally, scanning electron microscopic examination revealed the presence of extensive HA capsules in E. coli Rosetta-gamiB(DE3)pLysS, while no HA capsules were produced by B. megaterium. (3) Conclusions: Our results suggested that Gram-positive bacteria are probably superior host strains for recombinant HA production over their Gram-negative counters. The titers and the molecular weight (MW) of HA produced by B. megaterium were significantly higher than those obtained by different E. coli host strains used in this study.
Biofilm formation inside inserted medical devices leads to their failure and acts as a source of refractory infections. The ultraviolet C (UVC) light is a potential therapy that can be used against ...the biofilm of bacterial pathogens.
We evaluated the efficacy of sublethal dose of UVC light with anti-staphylococcal antibiotics against biofilms made from 30 isolates of methicillin-susceptible Staphylococcus aureus and methicillin-resistant S. aureus and S. epidermidis on vascular catheters.
A novel biofilm device was used to assess the combined approach. The biofilms on the catheters were irradiated with the UVC light at 254 nm and irradiance of 6.4 mW followed by treatment with vancomycin or quinupristin/dalfopristin at twice their minimum bactericidal concentrations or with linezolid at 64 µg/mL for 24 hours. The catheters were cut into segments and sonicated, and the number of the sessile cells was determined colorimetrically using XTT viable cells assay. The effect of UVC radiation followed by treatment with an antistaphylococcal antibiotic on the viability of the bacteria in the biofilm was visualized using LIVE/DEAD BacLight bacterial viability stain and confocal laser scanning microscopy.
Exposure of the bacterial biofilms to the UVC light or each of the antibiotics alone was ineffective in killing the bacteria. Treatment of the biofilms with the antibiotics following their exposure to UVC light significantly (P<0.001) reduced the number of viable cells within the biofilms but did not completely eradicate them.
To our knowledge, this combinatorial approach has not been investigated before. The combined approach can be used as a therapeutic modality for managing biofilm-associated infections by preventing the establishment of biofilms and/or disrupting the formed biofilms on the inserted medical devices with the goal of increasing their usefulness and preventing infectious complications. Further investigations are needed to assess the effectiveness of the combined approach in the clinical settings.
•Assessment of some clayey materials suitability in the production of ceramic membranes for electrochemical applications.•The valorization of shalky algae (Natural waste) as porosity agents in the ...manufacturing of membrane filters resulting in an ecofriendly and low-cost product (circular economy).•Study of the dielectric properties together with filtration performances of the manufactured membranes.
Novel ceramic membrane filters were manufactured from kaolino-illitic clays and calcareous algae (up to 20 wt.%) as porogenic agent. The produced membranes were investigated using X-ray diffraction, thermogravimetric analysis, scanning electron microscope, impedance spectroscopy, and Fourier-transform infrared spectroscopy. All of the filtration suitability, electrical properties, and dielectric behavior were assessed and interrelated to the microstructure. It was found that the original clay minerals were involved in the mineralization development while the inclusion of large pores (8–12 μm) was observed at high magnification alongside porosity increase (up to 70%) due to the addition of the bio-based pore-former. Both electric and dielectric measurements revealed that the sintering process was governed by the densification phenomenon and was accompanied with lower activation energy. The order of magnitude of the values taken by electrical impedance was close to average Mega-Ohms suggesting the suitability of the produced ceramic membranes as an electrical insulator for typical electrochemical devices. The tests of filtration have shown that the ceramic membranes produced operate normally in the microfiltration range for a period of 50 min without clogging and at pressures up to 0.12 bar. Conclusively, the developed ceramic membranes could be considered for applications in industrial wastewater treatment and electrochemical media.
In addition to this, a perspective has been proposed on the improvement paths or designs for ceramic membrane filters with good performance in wastewater treatment present in some electrochemical environments as well as methods to cope with the challenges regarding the performance of such materials.
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