Plasma membrane damage triggered by benzalkonium chloride and cetylpyridinium chloride induces G0/G1 cell cycle arrest via Cdc6 reduction in human lung epithelial cells

Quaternary ammonium compounds, including benzalkonium chloride (BAC) and cetylpyridinium chloride (CPC), are widely used as disinfectants. Increased use of inhalable products containing BAC or CPC has raised concerns for lung toxicity. This study sought to elucidate the microstructure of plasma membrane damage caused by BAC and CPC and the subsequent mechanism by which the damage is mediated, as assessed using two human pulmonary epithelial cell lines (A549 and BEAS-2B). Scanning electron microscopic observation showed that exposure to BAC or CPC for 3 hr reduced the length and density of microvilli on the plasma membrane in A549 cells. Analysis of cell cycle distribution following plasma membrane damage revealed that BAC and CPC promote G₀/G₁ cell cycle arrest in both cell lines. The protein levels of Cdc6, an essential regulator of DNA replication during G₁/S transition, are decreased significantly and dose dependently by BAC or CPC exposure. CPC and BAC decreased the Cdc6 levels that had been increased by a PI3K agonist in A549 cells, and levels of phosphorylated AKT were reduced in response to BAC or CPC. Conversely, exposure to equivalent concentrations of pyridinium chloride (lacking a hydrocarbon tail) induce no changes. These results suggest that plasma membrane damage triggered by BAC or CPC causes Cdc6-dependent G₀/G₁ cell cycle arrest in pulmonary cells. These effects are attributable to the long alkyl chains of BAC and CPC. The reduction of Cdc6 following plasma membrane damage may be caused, at least in part, by diminished signaling via the PI3K/AKT pathway.

Early-Life Exposure to Traffic-Related Air Pollutants Induced Anxiety-like Behaviors in Rats via Neurotransmitters and Neurotrophic Factors

Recent epidemiological studies have reported significantly increasing hospital admission rates for mental disorders such as anxiety and depression, not only in adults but also in children and adolescents, indicating more research is needed for evaluation of the etiology and possible reduction and prevention of these disorders. The aim of the present study was to examine the associations between perinatal exposure to traffic-related air pollutants and anxiety-like behaviors and alterations in neurological and immunological markers in adulthood using a rat model. Sprague Dawley pregnant rats were exposed to clean air (control), diesel exhaust (DE) 101 ± 9 μg/m³ or diesel exhaust origin secondary organic aerosol (DE-SOA) 118 ± 23 μg/m³ from gestational day 14 to postnatal day 21. Anxiety-related behavioral tests including open field tests, elevated plus maze, light/dark transition tests and novelty-induced hypophagia were performed on 10-week-old rats. The hippocampal expression of neurotransmitters, neurotrophic factors, and inflammatory molecular markers was examined by real-time RT-PCR. Anxiety-like behaviors were observed in both male and female rat offspring exposed to DE or DE-SOA. Moreover, serotonin receptor (5HT1A), dopamine receptor (Drd2), brain-derived neurotrophic factor and vascular endothelial growth factor A mRNAs were significantly decreased, whereas interleukin-1β, cyclooxygenase-2, heme oxygenase-1 mRNAs and microglial activation were significantly increased in both male and female rats. These findings indicate that brain developmental period exposure to traffic-related air pollutants may induce anxiety-like behaviors via modulation of neurotransmitters, neurotrophic factors, and immunological molecular markers, triggering neuroinflammation and microglia activation in rats.

Promyelocytic leukemia nuclear body-like structures can assemble in mouse oocytes

Promyelocytic leukemia (PML) nuclear bodies (PML-NBs), a class of membrane-less cellular organelles, participate in various biological activities. PML-NBs are known as the core-shell-type nuclear body, harboring ‘client’ proteins in their core. Although multiple membrane-less organelles work in the oocyte nucleus, PML-NBs have been predicted to be absent from oocytes. Here, we show that some well-known PML clients (but not endogenous PML) co-localized with small ubiquitin-related modifier (SUMO) protein in the nucleolus and peri-centromeric heterochromatin of maturing oocytes. In oocytes devoid of PML-NBs, endogenous PML protein localized in the vicinity of chromatin. During and after meiotic resumption, PML co-localized with SUMO gathering around chromosomes. To examine the benefit of the PML-NB-free intranuclear milieu in oocytes, we deliberately assembled PML-NBs by microinjecting human PML-encoding plasmids into oocytes. Under conditions of limited SUMO availability, assembled PML-NBs tended to cluster. Upon proteotoxic stress, SUMO delocalized from peri-centromeric heterochromatin and co-localized with SC35 (a marker of nuclear speckles)-positive large compartments, which was disturbed by pre-assembled PML-NBs. These observations suggest that the PML-NB-free intranuclear environment helps reserve SUMO for emergent responses by redirecting the flux of SUMO otherwise needed to maintain PML-NB dynamics.

Summary: PML-NB-free intranuclear environment in the oocyte helps reserve SUMO for emergent responses by redirecting the flux of SUMO otherwise needed to maintain PML-NB dynamics.

Scavenger receptor MARCO contributes to cellular internalization of exosomes by dynamin-dependent endocytosis and macropinocytosis

Macrophage receptor with collagenous structure (MARCO) is a scavenger receptor class-A protein that is expressed on the cell surface of macrophages. MARCO mediates binding and ingestion of unopsonized environmental particles, including nano-sized materials. Exosomes are cell-derived, nano-sized vesicles (40–150 nm) that can contain lipids, RNA, DNA, and various proteins. Exosomes play an essential role in cell-to-cell communication via body fluids. However, mechanisms for the recognition and internalization of exosomes by recipient cells remain poorly characterized. In this study, cellular association of serum-derived fluorescent exosomes and 20-nm fluorescent nanoparticles (positive control) was compared between MARCO-expressing (CHO-MARCO) and control (CHO-CT) CHO-K1 cells to examine whether MARCO expression by recipient cells mediates the cellular uptake of exosomes and environmental nanoparticles. Fluorescence microscopic studies and quantitative analyses revealed that the cellular associations of both exosomes and 20-nm nanoparticles were greater in CHO-MARCO cells than in CHO-CT cells. Exosomes and nanoparticles colocalized with green fluorescent protein (GFP)-MARCO in cells transfected with GFP-MARCO-encoding constructs . Furthermore, inhibitory studies showed that actin reorganization and dynamin are involved in the MARCO-mediated cellular internalization of exosomes. These results indicated that MARCO plays a role in the uptake of exosomes.

Phase I/II study of adding intraperitoneal paclitaxel in patients with pancreatic cancer and peritoneal metastasis

BACKGROUND

Intraperitoneal chemotherapy using paclitaxel is considered an experimental approach for treating peritoneal carcinomatosis. This study aimed to determine the recommended dose, and to evaluate the clinical efficacy and safety, of the combination of intravenous gemcitabine, intravenous nab-paclitaxel and intraperitoneal paclitaxel in patients with pancreatic cancer and peritoneal metastasis.

METHODS

The frequencies of dose-limiting toxicities were evaluated, and the recommended dose was determined in phase I. The primary endpoint of the phase II analysis was overall survival rate at 1 year. Secondary endpoints were antitumour effects, symptom-relieving effects, safety and overall survival.

RESULTS

The recommended doses of intravenous gemcitabine, intravenous nab-paclitaxel and intraperitoneal paclitaxel were 800, 75 and 20 mg/m² respectively. Among 46 patients enrolled in phase II, the median time to treatment failure was 6·0 (range 0-22·6) months. The response and disease control rates were 21 of 43 and 41 of 43 respectively. Ascites disappeared in 12 of 30 patients, and cytology became negative in 18 of 46. The median survival time was 14·5 months, and the 1-year overall survival rate was 61 per cent. Conversion surgery was performed in eight of 46 patients, and those who underwent resection survived significantly longer than those who were not treated surgically (median survival not reached versus 12·4 months). Grade 3-4 haematological toxicities developed in 35 of 46 patients, whereas non-haematological adverse events occurred in seven patients.

CONCLUSION

Adding intraperitoneal paclitaxel had clinical efficacy with acceptable tolerability.

Biotransformation of arsenic and toxicological implication of arsenic metabolites

Arsenic is a well-known environmental carcinogen and chronic exposure to arsenic through drinking water has been reported to cause skin, bladder and lung cancers, with arsenic metabolites being implicated in the pathogenesis. In contrast, arsenic trioxide (As₂O₃) is an effective therapeutic agent for the treatment of acute promyelocytic leukemia, in which the binding of arsenite (iAs^III) to promyelocytic leukemia (PML) protein is the proposed initial step. These findings on the two-edged sword characteristics of arsenic suggest that after entry into cells, arsenic reaches the nucleus and triggers various nuclear events. Arsenic is reduced, conjugated with glutathione, and methylated in the cytosol. These biotransformations, including the production of reactive metabolic intermediates, appear to determine the intracellular dynamics, target organs, and biological functions of arsenic.

Delayed gastric emptying after pancreatoduodenectomy: comparison between invaginated pancreatogastrostomy and pancreatojejunostomy

Background

The association between delayed gastric emptying (DGE) after pancreatoduodenectomy (PD) and pancreatic reconstruction technique remain unclear. The aim of this study is to investigate whether the occurrence of DGE differs between pancreaticojejunostomy (PJ) and pancreaticogastrostomy (PG).

Methods

A total of 83 patients who underwent subtotal stomach-preserving pancreatoduodenectomy was retrospectively analyzed, and the factors associated with clinically relevant DGE were explored. These patients were divided into a PG group and a PJ group according to the pancreatic reconstruction. DGE occurrence and its association with intra-abdominal complications was compared between the two types of pancreatic reconstruction.

Results

The overall incidence of DGE was 27.7%. Intra-abdominal complications including pancreatic fistula were strongly associated with DGE. As to the pancreatic reconstruction, DGE developed more frequently in the PG than in the PJ. In addition, DGE with intra-abdominal complications tended to be more frequent in PG, despite the fact that intra-abdominal complications occurred at a similar frequency in both groups.

Conclusions

Intra-abdominal complications were strongly associated with DGE. As to the pancreatic reconstruction, DGE developed more frequently in the PG than in the PJ. We speculate that intra-abdominal complications affected patients with PG more and resulted in frequent occurrence of DGE.

Relevance of autophagy markers to cytotoxicity of zinc compounds in macrophages

Autophagy molecules such as microtubule-associated protein light chain 3 (LC3) and p62/SQSTM1 have been used as biomarkers of protective or conversely adverse effects of exposure to toxicants. In the present study we show changes in LC3-II (a lipidated form of LC3-I) and p62 levels in response to zinc compounds and some other toxicants in J774.1 murine macrophages. The cytotoxicity of either ZnO or ZnSO₄ largely depended on the concentration of FBS or albumin in the culture medium. Accordingly, these authophagy markers were more remarkably increased when the cells were exposed to ZnO or ZnSO₄ in the absence of FBS. We next addressed lysosomal function impairment and changes in LC3-II and p62 levels following exposure to TiO₂, ZnO, and ZnSO₄. Lysosomal pH was quickly decreased by autolysosome inhibitors such as bafilomycin A1 and chloroquine, while TiO₂, ZnO and ZnSO₄ did not decrease lysosomal pH. However, the amounts of LC3-II and p62 and the LC3-II/LC3-I ratio were increased either by the lysosomal inhibitors and the Zn compounds. LC3-II and p62 levels were increased after exposure to arsenite and lipopolysaccharide (LPS). The p62 and phospho-p62 levels were also increased by either ZnSO₄ and bafilomycin A1 in HEK293 cells stably expressing RFP-LC3. The current observations suggest that LC3-II and p62 levels were increased as consequences of early effects of toxicants without changing lysosomal pH.

Safety and efficacy of PD-1/PD-L1 blockade in patients with preexisting antinuclear antibodies

PURPOSE

Immune checkpoint inhibitors (ICIs) show promising clinical activity in advanced cancers. However, the safety and efficacy of PD-1/PD-L1 blockade in patients with preexisting antinuclear antibodies (ANA) are unclear.

METHODS

191 patients treated with nivolumab, pembrolizumab, atezolizumab, or durvalumab for unresectable advanced cancers between September 2014 and December 2018 were identified retrospectively. Patients were divided into positive (ANA titers ≥ 1:160) and negative ANA groups (ANA titers < 1:160). Development of immune-related adverse events (irAEs), the overall response rate (ORR), and disease control rate (DCR) were monitored.

RESULTS

Positive ANA titers were seen in 9 out of 191 patients. Four patients in the positive ANA group and 69 patients in the negative group developed irAEs of any grade without a significant difference between the groups. The development of endocrine, pulmonary, and cutaneous irAEs was not significant, whereas positive ANA was significantly higher in patients who developed colitis (2/9) than in patients who did not (3/182, P = 0.0002). DCR in the positive and negative ANA group was 37.5% and 67.5%, respectively, and was not statistically significant, but had better efficacy in patients without ANA (P = 0.08). ANA-related autoimmune diseases such as SLE, Sjögren's syndrome, MCTD, scleroderma, dermatomyositis, and polymyositis was not induced in either group. However, one patient with preexisting dermatomyositis had a flare up after initiation of atezolizumab.

CONCLUSION

Further studies to identify predictive factors for the development of irAEs are required to provide relevant patient care and maximize the therapeutic benefits of ICIs.

The toxicological analysis of secondary organic aerosol in human lung epithelial cells and macrophages

Secondary organic aerosol (SOA) is a component of airborne particulate matter in urban areas. However, their toxicities remain incompletely understood. In this study, we investigated the oxidative and inflammatory potency of SOA derived from three different volatile organic compounds (α-pinene, m-xylene, and trimethylbenzene) using human bronchial epithelial cells (BEAS-2B) and macrophages (U937). In BEAS-2B cells, all types of SOA extracts increased the expression of the heme oxygenase 1 (HMOX1) and interleukin-8 (IL8) genes, a typical marker for oxidative stress and inflammatory responses, respectively. Among the three types of SOA, m-xylene-derived SOA showed the strongest induction of the HMOX1 and IL8 genes, and transcriptional activity via the antioxidant response element (ARE). A causal candidate for SOA induction of oxidative stress is 2,6-dimethyl-1,4-benzoquinone (DMBQ) because only this quinone compound increased the transcriptional activity via ARE among components tested in this study. Similar to the case of BEAS-2B cells, SOA extracts increased the expression of HMOX1 and IL8 genes in U937 cells, mainly through oxidative stress, but these responses in U937 cells were prolonged when compared with BEAS-2B cells. Together, these results show that SOA affects lung epithelial cells and macrophages mainly through oxidative stress and inflammation, suggesting their contribution to the development of respiratory diseases.

Effects of pharmacological lesion of the nucleus retroambiguus region on the pharyngeal phase of swallowing

Pharyngeal swallowing is controlled by synaptic interactions within a swallowing central pattern generator (sw-CPG) that is composed of a dorsal and a ventral swallowing group (VSG). Here, we used electrical stimulation (10 s) of the superior laryngeal nerve (SLN; 20 Hz; pulse width: 100 μs) to explore the role of the VSG in an arterially-perfused brainstem preparation of rats. To investigate the effects of pharmacological lesion (local microinjection of an GABA(A)-R agonist) of the nucleus retroambiguus (NRA), a designated component of the VSG, we recorded phrenic (PNA) and vagal nerve (VNA) activities. Control SLN stimulation with stepwise increasing stimulus intensities (from 20 μA to 160 μA) elicited robust suppression of PNA and evoked sequential swallowing activity in the VNA. Lesioning of the NRA had no effect on the pattern of pharyngeal swallowing, but significantly increased the sensory gating of SLN inputs. We conclude that the NRA is not part of the VSG, but appears to have important roles for the central gating of swallowing.

Characterization and influence of hydroxyapatite nanopowders on living cells

Nanomaterials, such as hydroxyapatite nanoparticles show a great promise for medical applications due to their unique properties at the nanoscale. However, there are concerns about the safety of using these materials in biological environments. Despite a great number of published studies of nanoobjects and their aggregates or agglomerates, the impact of their physicochemical properties (such as particle size, surface area, purity, details of structure and degree of agglomeration) on living cells is not yet fully understood. Significant differences in these properties, resulting from different manufacturing methods, are yet another problem to be taken into consideration. The aim of this work was to investigate the correlation between the properties of nanoscale hydroxyapatite from different synthesis methods and biological activity represented by the viability of four cell lines: A549, CHO, BEAS-2B and J774.1 to assess the influence of the nanoparticles on immune, reproductive and respiratory systems.

Randomized clinical trial of adjuvant gemcitabine chemotherapy versus observation in resected bile duct cancer

BACKGROUND

Although some retrospective studies have suggested the value of adjuvant therapy, no recommended standard exists in bile duct cancer. The aim of this study was to test the hypothesis that adjuvant gemcitabine chemotherapy would improve survival probability in resected bile duct cancer.

METHODS

This was a randomized phase III trial. Patients with resected bile duct cancer were assigned randomly to gemcitabine and observation groups, which were balanced with respect to lymph node status, residual tumour status and tumour location. Gemcitabine was given intravenously at a dose of 1000 mg/m² , administered on days 1, 8 and 15 every 4 weeks for six cycles. The primary endpoint was overall survival, and secondary endpoints were relapse-free survival, subgroup analysis and toxicity.

RESULTS

Some 225 patients were included (117 gemcitabine, 108 observation). Baseline characteristics were well balanced between the gemcitabine and observation groups. There were no significant differences in overall survival (median 62·3 versus 63·8 months respectively; hazard ratio 1·01, 95 per cent c.i. 0·70 to 1·45; P = 0·964) and relapse-free survival (median 36·0 versus 39·9 months; hazard ratio 0·93, 0·66 to 1·32; P = 0·693). There were no survival differences between the two groups in subsets stratified by lymph node status and margin status. Although haematological toxicity occurred frequently in the gemcitabine group, most toxicities were transient, and grade 3/4 non-haematological toxicity was rare.

CONCLUSION

The survival probability in patients with resected bile duct cancer was not significantly different between the gemcitabine adjuvant chemotherapy group and the observation group. Registration number: UMIN 000000820 (http://www.umin.ac.jp/).