What if cell culture media do not mimic in vivo redox settings?

Convergence of plant sterols and host eukaryotic cell-derived defensive lipids at the infectious pathogen-host interface

Plant sterols (PSs) exhibit intrinsic functions such as antibacterial effects. Their effects simultaneously on both host-mediated and bacteria-mediated pathogenesis are not yet fully understood. We hypothesized that when absorptive cells, defensive cells and detoxer cells are cultured together, their convergent response to an infectious pathogen depends on the molecular mimicry between the ingested sterols and their own defensive lipids. A human triple cell co-culture model incorporating colonocytes, macrophages, and hepatocytes was established. Cocultures were stimulated with Klebsiella pneumoniae 52145 (Kp52145) in the presence of pure plant sterol (β-sitosterol, PS) for 6 h. Changes in the structural health markers of the stimulated cocultured cells and their immune response and biochemical markers of pathogenicity were determined. PS significantly inhibited the secretion of cytokines induced by Kp52145. Cell viability was higher in the Kp52145 + PS group compared to the Kp52145 alone group. PS decreased Kp52145-induced marker of pathogenicity (SOD), accompanied by reduced levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), mannose binding lectin (MBL), and pentraxin 3 (PTX3) which are the mediators and enzymes associated with the inflammatory response to an infectious-inflamed milieu. PS recovered Kp52145-decreased peroxidase (POX), catalase (CAT), complement component 3 (C3), and high-density lipoprotein cholesterol (HDL-C) values. Convergence of ingested plant sterols and host eukaryotic cell-derived defensive lipids mitigates the disruptive effects of bacterial toxic effector molecules. Structural or immunological similarities (molecular mimicry) between ingested plant sterols and host defensive lipids play an important role in modulating bacterial signalling that occurs at the pathogen-host interface and in the mitigation of infection- and inflammation-driven pathological processes.

Quantitative Factors Introduced in the Feasibility Analysis of Reactive Oxygen Species (ROS)-Sensitive Triggers

Reactive oxygen species (ROS) are critical for cellular signaling. Various pathophysiological conditions are also associated with elevated levels of ROS. Hence, ROS-sensitive triggers have been extensively used for selective payload delivery. Such applications are predicated on two key functions: (1) a sufficient magnitude of concentration difference for the interested ROS between normal tissue/cells and intended sites and (2) appropriate reaction kinetics to ensure a sufficient level of selectivity for payload release. Further, ROS refers to a group of species with varying reactivity, which should not be viewed as a uniform group. In this review, we critically analyze data on the concentrations of different ROS species under various pathophysiological conditions and examine how reaction kinetics affect the success of ROS-sensitive linker chemistry. Further, we discuss different ROS linker chemistry in the context of their applications in drug delivery and imaging. This review brings new insights into research in ROS-triggered delivery, highlights factors to consider in maximizing the chance for success and discusses pitfalls to avoid.

The motor system is exceptionally vulnerable to absence of the ubiquitously expressed superoxide dismutase-1

Superoxide dismutase-1 is a ubiquitously expressed antioxidant enzyme. Mutations in SOD1 can cause amyotrophic lateral sclerosis, probably via a toxic gain-of-function involving protein aggregation and prion-like mechanisms. Recently, homozygosity for loss-of-function mutations in SOD1 has been reported in patients presenting with infantile-onset motor neuron disease. We explored the bodily effects of superoxide dismutase-1 enzymatic deficiency in eight children homozygous for the p.C112Wfs*11 truncating mutation. In addition to physical and imaging examinations, we collected blood, urine and skin fibroblast samples. We used a comprehensive panel of clinically established analyses to assess organ function and analysed oxidative stress markers, antioxidant compounds, and the characteristics of the mutant Superoxide dismutase-1. From around 8 months of age, all patients exhibited progressive signs of both upper and lower motor neuron dysfunction, cerebellar, brain stem, and frontal lobe atrophy and elevated plasma neurofilament concentration indicating ongoing axonal damage. The disease progression seemed to slow down over the following years. The p.C112Wfs*11 gene product is unstable, rapidly degraded and no aggregates were found in fibroblast. Most laboratory tests indicated normal organ integrity and only a few modest deviations were found. The patients displayed anaemia with shortened survival of erythrocytes containing decreased levels of reduced glutathione. A variety of other antioxidants and oxidant damage markers were within normal range. In conclusion, non-neuronal organs in humans show a remarkable tolerance to absence of Superoxide dismutase-1 enzymatic activity. The study highlights the enigmatic specific vulnerability of the motor system to both gain-of-function mutations in SOD1 and loss of the enzyme as in the here depicted infantile superoxide dismutase-1 deficiency syndrome.

Characterization of ion release from a novel biomaterial, Molybdenum-47.5Rhenium, in physiologic environments

BACKGROUND CONTEXT

Metals from spinal implants are released into surrounding tissues by various mechanisms. Metal ion release has been associated with clinical implant failure, osteolysis, and remote site accumulation with adverse events. Significant corrosion and associated metal ion release has been described with currently used spinal implant alloys. A novel metal alloy, Molybdenum-47.5Rhenium alloy (MoRe®), was approved for use in medical implants in 2019 by the FDA.

PURPOSE

To evaluate the metal ion release profile of MoRe alloy after immersion in both a stable physiologic, as well as in an inflammatory environment.

STUDY DESIGN

In vitro study.

METHODS

The ion release profile of the MoRe alloy was comprehensively evaluated in-vitro after prolonged immersion in physiologic and inflammatory environments. Ion concentration analyses were then conducted using inductively coupled plasma-mass spectrometry (ICP-MS) methods. Comparative testing of titanium (Ti-6Al-4V) and cobalt chromium (Co-28Cr-6Mo) was also performed.

RESULTS

Under baseline physiologic conditions, the MoRe alloy demonstrates very low molybdenum and rhenium ion release rates throughout the 30-day test period. During the first time interval (day 0-1), low levels of molybdenum and rhenium ions are detected (<0.3 μg/cm² day) followed by a rapid reduction in the ion release rates to <0.05 μg/cm² day during the second time interval (days 1-3) followed by a further reduction to very low steady-state rates <0.01 μg/cm² day during the third time interval (days 3-7), which were maintained through 30 days. In the inflammatory condition (H₂O₂ solution), there was a transient increase in the release of molybdenum and rhenium ions, followed by a return to baseline ion release rates (days 2-4), with a further reduction to low steady-state rates of ∼0.01 μg/cm² day (days 4-8). The measured molybdenum and rhenium ion release rates in both steady state (<0.01 μg/cm² day), and inflammatory environments (0.01 μg/cm² day) were far below the established FDA-permitted daily exposure (PDE) of 1,900 μg/cm² day for molybdenum and 4,400 μg/cm² day for rhenium. In contrast, titanium and cobalt chromium approached or exceeded their established PDE values in an inflammatory environment.

CONCLUSIONS

The novel biomaterial MoRe demonstrated a lower metal ion release profile in both a physiologic and inflammatory environment and was well below the established PDE.  Comparative testing of the cobalt-chromium and titanium alloys found higher levels of ion release in the inflammatory environment that exceeded the PDE for cobalt and vanadium.

Probing Subcellular Iron Availability with Genetically Encoded Nitric Oxide Biosensors

Cellular iron supply is required for various biochemical processes. Measuring bioavailable iron in cells aids in obtaining a better understanding of its biochemical activities but is technically challenging. Existing techniques have several constraints that make precise localization difficult, and the lack of a functional readout makes it unclear whether the tested labile iron is available for metalloproteins. Here, we use geNOps; a ferrous iron-dependent genetically encoded fluorescent nitric oxide (NO) biosensor, to measure available iron in cellular locales. We exploited the nitrosylation-dependent fluorescence quenching of geNOps as a direct readout for cellular iron absorption, distribution, and availability. Our findings show that, in addition to ferrous iron salts, the complex of iron (III) with N,N'-bis (2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) can activate the iron (II)-dependent NO probe within intact cells. Cell treatment for only 20 min with iron sucrose was also sufficient to activate the biosensor in the cytosol and mitochondria significantly; however, ferric carboxymaltose failed to functionalize the probe, even after 2 h of cell treatment. Our findings show that the geNOps approach detects available iron (II) in cultured cells and can be applied to assay functional iron (II) at the (sub)cellular level.

The effects of violet and blue light irradiation on ESKAPE pathogens and human cells in presence of cell culture media

Bacteria belonging to the group of ESKAPE pathogens are responsible for the majority of nosocomial infections. Due to the increase of antibiotic resistance, alternative treatment strategies are of high clinical relevance. In this context visible light as disinfection technique represents an interesting option as microbial pathogens can be inactivated without adjuvants. However cytotoxic effects of visible light on host cells have also been reported. We compared the cytotoxicity of violet and blue light irradiation on monocytic THP-1 and alveolar epithelium A549 cells with the inactivation effect on ESKAPE pathogens. THP-1 cells displayed a higher susceptibility to irradiation than A549 cells with first cytotoxic effects occurring at 300 J cm⁻² (405 nm) and 400 J cm⁻² (450 nm) in comparison to 300 J cm⁻² and 1000 J cm⁻², respectively. We could define conditions in which a significant reduction of colony forming units for all ESKAPE pathogens, except Enterococcus faecium, was achieved at 405 nm while avoiding cytotoxicity. Irradiation at 450 nm demonstrated a more variable effect which was species and medium dependent. In summary a significant reduction of viable bacteria could be achieved at subtoxic irradiation doses, supporting a potential use of visible light as an antimicrobial agent in clinical settings.

Role of the high-affinity reductive iron acquisition pathway of Candida albicans in prostaglandin E2 production, virulence, and interaction with Pseudomonas aeruginosa

Components of the iron reductive pathway of Candida albicans have been implicated in the production of prostaglandin E2 (PGE2) and virulence. However, it is unknown whether other components of this pathway influence PGE2. We investigated the role of the iron reductive pathway of C. albicans in biofilm formation, PGE2 production, and virulence in Caenorhabditis elegans. Additionally, as the co-occurrence of C. albicans and Pseudomonas aeruginosa in host tissues is frequent and involves competition for host-associated iron, we examined the effects of this interaction. Deletion of multicopper oxidase gene, FET99, and iron permease genes, FTH1 and FTH2, affected biofilm metabolic activity, and for the FTH2 mutant, also biofilm morphology. Deletion of CCC1 (vacuolar iron transporter) and CCC2 (P-type ATPase copper importer) also influenced biofilm morphology. For PGE2 production, deletion of FET99, FTH1, FTH2, CCC1, and CCC2 caused a significant reduction by monomicrobial biofilms, while FTH2deletion caused the highest reduction in polymicrobial biofilms. URA3 positive mutants of FET99 and FTH2 demonstrated attenuated virulence in C. elegans, potentially due to the inability of mutants to form hyphae in vivo. Deductively, the role of the iron reductive pathway in PGE2 synthesis is indirect, possibly due to their role in iron homeostasis.

LAY SUMMARY

Iron uptake is vital for disease-causing microbes like Candida albicans. Using strains deficient in some iron-uptake genes, we show that iron-uptake genes, especially FET99 and FTH2, play a role in biofilm formation, prostaglandin production, and virulence in the nematode infection model.

Ficus carica leaves extract inhibited pancreatic β-cell apoptosis by inhibiting AMPK/JNK/caspase-3 signaling pathway and antioxidation

The aim of this study was to explore the inhibitory effects of Ficus carica leaves (FCL) extract on AMPK/JNK/caspase3 signaling pathway and antioxidation in pancreatic β-cells. H&E staining, insulin immunohistochemistry, and TUNEL methods were used to investigate the effects of FCL on pancreatic histopathology in type 1 diabetic mice. The expression levels of caspase-3, AMPK, and JNK protein in the pancreatic tissue and MIN6 cells [induced by palmitic acid (PA) and hydrogen peroxide] were determined. Flow cytometry was used to detect the effects of FCL on apoptosis and ROS production of MIN6 cells. FCL (2 g/kg, continuous gavage for 6 weeks) significantly improved the pancreatic tissue injury in type 1 diabetic mice and reduced the expression levels of apoptosis-related proteins such as FasL, caspase8, Bax/Bcl-2, Cyt-C, caspase-3, p-AMPK, and p-JNK. FCL inhibited cell apoptosis induced by PA and the protein expression levels of caspase-3, p-AMPK, and p-JNK. The AMPK agonist AICAR could reverse the protective effects of FCL on MIN6 cells. The AMPK inhibitor compound C had a similar effect on MIN6 cells as that of FCL. FCL could inhibit cell apoptosis induced by hydrogen peroxide and reduced the production of ROS. In conclusion, FCL could inhibit pancreatic β-cell apoptosis by inhibiting the AMPK/JNK/caspase-3 signaling pathway and by antioxidation properties.

Hispolon suppresses migration and invasion of human nasopharyngeal carcinoma cells by inhibiting the urokinase-plasminogen activator through modulation of the Akt signaling pathway

Hispolon has been reported to possess antioxidant, antiinflammatory, and antitumor activities. However, the effect of hispolon on the metastasis of nasopharyngeal carcinoma (NPC) remains unclear. In this study, we investigated how the antimetastatic activity and relevant signaling pathways of hispolon affected three NPC cell lines. The results revealed that hispolon significantly reduced the migration and invasion of three NPC cells in a dose-dependent manner from 0 to 50 µM. Hispolon also significantly inhibited the activity and expression of urokinase-plasminogen activator (uPA) as well as the phosphorylation of Akt. Moreover, blocking the Akt pathway also enhanced the antimetastatic ability of hispolon in the NPC cells. In conclusion, hispolon inhibited uPA expression and NPC cell metastasis by downregulating Akt signal pathways; therefore, hispolon exerts beneficial effects in chemoprevention. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 645-655, 2017.