Alternative autophagy dampens UVB-induced NLRP3 inflammasome activation in human keratinocytes.

Sunlight exposure results in an inflammatory reaction of the skin commonly known as sunburn, which increases skin cancer risk. In particular, the ultraviolet B (UVB) component of sunlight induces inflammasome activation in keratinocytes to instigate the cutaneous inflammatory responses. Here, we explore the intracellular machinery that maintains skin homeostasis by suppressing UVB-induced inflammasome activation in human keratinocytes. We found that pharmacological inhibition of autophagy promoted UVB-induced NLRP3 inflammasome activation. Unexpectedly, however, gene silencing of Atg5 or Atg7, which are critical for conventional autophagy, had no effect, whereas gene silencing of Beclin1, which is essential not only for conventional autophagy but also for Atg5/Atg7-independent alternative autophagy, promoted UVB-induced inflammasome activation, indicating an involvement of alternative autophagy. We found that damaged mitochondria were highly accumulated in UVB-irradiated keratinocytes when alternative autophagy was inhibited, and they appear to be recognized by NLRP3. Overall, our findings indicate that alternative autophagy, rather than conventional autophagy, suppresses UVB-induced NLRP3 inflammasome activation through the clearance of damaged mitochondria in human keratinocytes and illustrate a previously unknown involvement of alternative autophagy in inflammation. Alternative autophagy may be a new therapeutic target for sunburn and associated cutaneous disorders.

Influence of short-term hypoxic exposure on spatial learning and memory function and brain-derived neurotrophic factor in rats-A practical implication to human's lost way.

The present study aimed to investigate the effects of a short period of normobaric hypoxic exposure on spatial learning and memory, and brain-derived neurotrophic factor (BDNF) levels in the rat hippocampus. Hypoxic conditions were set at 12.5% O2. We compared all variables between normoxic trials (Norm), after 24 h (Hypo-24 h), and after 72 h of hypoxic exposure (Hypo-72 h). Spatial learning and memory were evaluated by using a water-finding task in an open field. Time to find water drinking fountains was significantly extended in Hypo 24 h (36.2 ± 21.9 s) compared to those in Norm (17.9 ± 12.8 s; P < 0.05), whereas no statistical differences between Norm and Hypo-72 h (22.7 ± 12.3 s). Moreover, hippocampal BDNF level in Hypo-24 h was significantly lower compared to Norm (189.4 ± 28.4 vs. 224.9 ± 47.7 ng/g wet tissue, P < 0.05), whereas no statistically differences in those between Norm and Hypo-72 h (228.1 ± 39.8 ng/g wet tissue). No significant differences in the changes in corticosterone and adrenocorticotropic hormone levels were observed across the three conditions. When data from Hypo-24 h and Hypo-72 h of hypoxia were pooled, there was a marginal negative relationship between the time to find drinking fountains and BDNF (P < 0.1), and was a significant negative relationship between the locomotor activities and BDNF (P < 0.05). These results suggest that acute hypoxic exposure (24 h) may impair spatial learning and memory; however, it recovered after 72 h of hypoxic exposure. These changes in spatial learning and memory may be associated with changes in the hippocampal BDNF levels in rats.

Adverse Tracheal Intubation Events in Critically Ill Underweight and Obese Children: Retrospective Study of the National Emergency Airway for Children Registry (2013-2020).

OBJECTIVES: Extremes of patient body mass index are associated with difficult intubation and increased morbidity in adults. We aimed to determine the association between being underweight or obese with adverse airway outcomes, including adverse tracheal intubation (TI)-associated events (TIAEs) and/or severe peri-intubation hypoxemia (pulse oximetry oxygen saturation < 80%) in critically ill children. DESIGN/SETTING: Retrospective cohort using the National Emergency Airway for Children registry dataset of 2013-2020. PATIENTS: Critically ill children, 0 to 17 years old, undergoing TI in PICUs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Registry data from 24,342 patients who underwent TI between 2013 and 2020 were analyzed. Patients were categorized using the Centers for Disease Control and Prevention weight-for-age chart: normal weight (5th-84th percentile) 57.1%, underweight (< 5th percentile) 27.5%, overweight (85th to < 95th percentile) 7.2%, and obese (≥ 95th percentile) 8.2%. Underweight was most common in infants (34%); obesity was most common in children older than 8 years old (15.1%). Underweight patients more often had oxygenation and ventilation failure (34.0%, 36.2%, respectively) as the indication for TI and a history of difficult airway (16.7%). Apneic oxygenation was used more often in overweight and obese patients (19.1%, 19.6%) than in underweight or normal weight patients (14.1%, 17.1%; p < 0.001). TIAEs and/or hypoxemia occurred more often in underweight (27.1%) and obese (24.3%) patients ( p < 0.001). TI in underweight children was associated with greater odds of adverse airway outcome compared with normal weight children after adjusting for potential confounders (underweight: adjusted odds ratio [aOR], 1.09; 95% CI, 1.01-1.18; p = 0.016). Both underweight and obesity were associated with hypoxemia after adjusting for covariates and site clustering (underweight: aOR, 1.11; 95% CI, 1.02-1.21; p = 0.01 and obesity: aOR, 1.22; 95% CI, 1.07-1.39; p = 0.002). CONCLUSIONS: In underweight and obese children compared with normal weight children, procedures around the timing of TI are associated with greater odds of adverse airway events.

Anesthetic Management of Inguinal Hernia Surgery Using a Second-Generation Supraglottic Airway in a Patient With Trisomy 18: A Case Report.

Children with trisomy 18 have abnormal airway anatomy, making their airway management challenging. Only a few papers have comprehensively described and discussed the use of supraglottic airway devices in patients with trisomy 18. We present a case of a 20-month-old boy with trisomy 18 who was scheduled for open repair of the right inguinal hernia. He had micrognathia, a short neck, and an atrial septal defect but was in a clinically stable condition. A supraglottic airway device was inserted under general anesthesia. The patient's respiration was maintained by pressure support ventilation with spontaneous breathing. A right ilioinguinal-iliohypogastric nerve block was performed for perioperative analgesia. The surgery ended without complications. After removing the supraglottic airway device and ensuring proper respiratory parameters, the patient was transferred to the post-anesthesia care unit. In our case, supraglottic airway devices could be effectively used as a primary airway for inguinal hernia repair. The concomitant ilioinguinal-iliohypogastric nerve block was helpful for anesthetic management with spontaneous breathing maintained using pressure support ventilation. A supraglottic airway device may be a potential alternative as a primary airway for superficial surgery in pediatric patients with trisomy 18. For pediatric patients with difficult airways, a second-generation supraglottic airway device with the insertion of a gastric tube to prevent gastric insufflation combining pressure support ventilation and positive end-expiratory pressure may be a beneficial choice for the maintenance of spontaneous breathing.

Cytotoxic CD4+ T cells eliminate senescent cells by targeting cytomegalovirus antigen.

Senescent cell accumulation has been implicated in the pathogenesis of aging-associated diseases, including cancer. The mechanism that prevents the accumulation of senescent cells in aging human organs is unclear. Here, we demonstrate that a virus-immune axis controls the senescent fibroblast accumulation in the human skin. Senescent fibroblasts increased in old skin compared with young skin. However, they did not increase with advancing age in the elderly. Increased CXCL9 and cytotoxic CD4+ T cells (CD4 CTLs) recruitment were significantly associated with reduced senescent fibroblasts in the old skin. Senescent fibroblasts expressed human leukocyte antigen class II (HLA-II) and human cytomegalovirus glycoprotein B (HCMV-gB), becoming direct CD4 CTL targets. Skin-resident CD4 CTLs eliminated HCMV-gB+ senescent fibroblasts in an HLA-II-dependent manner, and HCMV-gB activated CD4 CTLs from the human skin. Collectively, our findings demonstrate HCMV reactivation in senescent cells, which CD4 CTLs can directly eliminate through the recognition of the HCMV-gB antigen.

A case series describing the risk of periodontal disease in Marfan syndrome patients harboring a possible aortic aneurysm or dissection.

BACKGROUND: Marfan syndrome (MFS) is a systemic disorder of connective tissues caused by insufficient elastic fiber formation that leads to structural weakness and results in various tissue disorders, including cardiovascular and periodontal disease. Notably however, the risk of periodontal disease in MFS patients affected by an aortic aneurysm or dissection has not yet been clarified. METHODS: We investigated the periodontal condition in the following three groups: MFS patients diagnosed with an aortic aneurysm or dissection with a planned aortic surgery (MFS surgery), MFS patients who had already undergone aortic surgery (MFS post-surgery) and healthy control patients (Healthy). The periodontal condition of all of these patients was evaluated at their first visit, reassessed again at two-month after the first visit, and evaluated again at a six-month follow-up after the reassessment. RESULTS: A total of 14 participants, 3 MFS surgery patients, 4 MFS post-surgery patients and 7 healthy control volunteers were examined. Saliva examinations revealed no significant differences between any of the groups at the first visit, reassessment, or follow-up. Interestingly, the MFS surgery cases showed a higher BOP and PISA at the first visit and follow-up compared with the other groups. In contrast, the MFS surgery patients showed an improvement in their LVDd and EF values, both markers of cardiac function, at the reassessment and follow-up compared with the first visit. CONCLUSIONS: MFS associated with an aortic aneurysm or dissection leads to a higher risk of periodontal disease, indicating the need for more frequent oral hygiene maintenance in these patients. In addition, MFS patients who undergo frequent professional cleaning of their teeth show a lower onset of cardiovascular disease, suggesting that professional oral hygiene in these cases contributes to a healthier condition.

Cystine reduces mitochondrial dysfunction in C2C12 myotubes under moderate oxidative stress induced by H2O2.

Moderate oxidative stress induces temporal impairment in mitochondrial ATP production. As glutathione (GSH) content is reduced to eliminate oxidative stress by oxidation-reduction reaction, intracellular GSH content is crucial for maintaining mitochondrial function under oxidative stress. GSH precursors such as N-acetyl cysteine (NAC) and cysteine are known to suppress oxidative stress based on the supply of cysteine residues being rate-limiting for GSH synthesis. However, it remains unclear whether cystine (Cys2) can suppress mitochondrial dysfunction under oxidative stress conditions. Therefore, we examined whether Cys2 could attenuate mitochondrial dysfunction under moderate oxidative stress without scavenging reactive oxygen species (ROS) in the medium. C2C12 myotubes were incubated for 120 min in a Cys2-supplemented medium and subsequently exposed to hydrogen peroxide (H2O2). Heme oxygenase-1 (HO-1) gene expression, intracellular cysteine and GSH content, intracellular ATP level, and maximal mitochondrial respiration were assessed. Cys2 treatment significantly increased GSH content in a dose-dependent manner under oxidative stress. Cys2 treatment significantly decreased HO-1 expression induced by H2O2 exposure. In addition, maximal mitochondrial respiration rate was decreased by H2O2 exposure, but improved by Cys2 treatment. In conclusion, Cys2 treatment mitigates oxidative stress-induced mitochondrial dysfunction by maintaining GSH content under moderate oxidative stress without scavenging ROS in the medium.

Alarmin Cytokines as Central Regulators of Cutaneous Immunity.

Skin acts as the primary interface between the body and the environment. The skin immune system is composed of a complex network of immune cells and factors that provide the first line of defense against microbial pathogens and environmental insults. Alarmin cytokines mediate an intricate intercellular communication between keratinocytes and immune cells to regulate cutaneous immune responses. Proper functions of the type 2 alarmin cytokines, thymic stromal lymphopoietin (TSLP), interleukin (IL)-25, and IL-33, are paramount to the maintenance of skin homeostasis, and their dysregulation is commonly associated with allergic inflammation. In this review, we discuss recent findings on the complex regulatory network of type 2 alarmin cytokines that control skin immunity and highlight the mechanisms by which these cytokines regulate skin immune responses in host defense, chronic inflammation, and cancer.

Anesthetic management of a patient with Freeman-Sheldon syndrome undergoing oral surgery: A case report.

In the anesthetic management in this case was how to manage the patient without causing respiratory depression and respiratory muscle fatigue.

Cystine reduces tight junction permeability and intestinal inflammation induced by oxidative stress in Caco-2 cells.

Intestinal oxidative stress produces pro-inflammatory cytokines, which increase tight junction (TJ) permeability, leading to intestinal and systemic inflammation. Cystine (Cys2) is a substrate of glutathione (GSH) and inhibits inflammation, however, it is unclear whether Cys2 locally improves intestinal barrier dysfunction. Thus, we investigated the local effects of Cys2 on oxidative stress-induced TJ permeability and intestinal inflammatory responses. Caco-2 cells were cultured in a Cys2-supplemented medium for 24 h and then treated with H2O2 for 2 h. We assessed TJ permeability by measuring transepithelial electrical resistance and the paracellular flux of fluorescein isothiocyanate-dextran 4 kDa. We measured the concentration of Cys2 and GSH after Cys2 pretreatment. The mRNA expression of pro-inflammatory cytokines was assessed. In addition, the levels of TJ proteins were assessed by measuring the expression of TJ proteins in the whole cells and the ratio of TJ proteins in the detergent-insoluble fractions to soluble fractions (IS/S ratio). Cys2 treatment reduced H2O2-induced TJ permeability. Cys2 did not change the expression of TJ proteins in the whole cells, however, suppressed the IS/S ratio of claudin-4. Intercellular levels of Cys2 and GSH significantly increased in cells treated with Cys2. Cys2 treatment suppressed the mRNA expression of pro-inflammatory cytokines, and the mRNA levels were significantly correlated with TJ permeability. In conclusion, Cys2 treatment locally reduced oxidative stress-induced intestinal barrier dysfunction possively due to the mitigation of claudin-4 dislocalization. Furthermore, the effect of Cys2 on the improvement of intestinal barrier function is related to the local suppression of oxidative stress-induced pro-inflammatory responses.

Scientific justifications for the political decision-making on environmental remediation carried out after the Fukushima nuclear accident.

The Japanese government decided to implement environmental remediation after the Fukushima Daiichi Nuclear Power Plant (termed "1F" in Japan) accident on 11th March 2011. As the initial additional annual dose target was set to be 1 mSv or less as a long-term goal, we examined the decision-making process undertaken by the then leaders, particularly the Minister of the Ministry of the Environment (MOE) who was responsible for the final decision. We found that technically based assessment of dose targets, health effects and risk-based approaches justified by scientific experts were not communicated to the then Minister and officials of the MOE before the remediation strategy was decided. We defined how such a decision was made based on leadership theories such as the Role Theory and the Cognitive Resources Theory. Academic leaders could have examined the Windscale accident (UK, 1957), which could be considered as the closest analogue (at least in terms of radionuclide releases) to the 1F accident. Environmental remediation could have been planned and implemented more effectively whilst still maintaining the highest possible safety standards and balancing the environmental and economic burden. Appropriate scientific input should have been provided by academic leaders to political and administrative leaders and such scientific justification should have been disclosed to the general public (especially the residents of Fukushima Prefecture) so that the general public could have developed greater trust in their leaders and have more readily accepted the decisions made.

An experimental intraradicular biofilm model in the pig for evaluating irrigation techniques.

BACKGROUND: We established an in vivo intraradicular biofilm model of apical periodontitis in pigs in which we compared the efficacy of different irrigant activation techniques for biofilm removal. METHODS: Twenty roots from the deciduous mandibular second premolar of 5 male pigs were used. After pulpectomy, canals were left open for 2 weeks and then sealed for 4 weeks to enable the development of an intracanal biofilm. The intraradicular biofilms was evaluated using SEM and bacterial 16S rRNA gene-sequencing. To investigate the efficacy of biofilm removal, root canal irrigations were performed using conventional needle, passive ultrasonic, subsonic, or laser-activated irrigation. Real-time PCR was conducted to quantitate the remaining biofilm components. Statistical analysis was performed using ANOVA followed by a Tukey kramer post-hoc test with α = 0.05. RESULTS: The pulp exposure model was effective in inducing apical periodontitis and SEM analysis revealed a multi-layer biofilm formation inside the root canal. 16S rRNA sequence analysis identified Firmicutes, Bacteroidetes, and Fusobacteria as the predominant bacterial phyla components, which is similar to the microbiome profile seen in humans. None of the tested irrigation techniques completely eradicated the biofilm components from the root canal, but the subsonic and laser-activated irrigation methods produced the lowest bacterial counts (p < 0.05). CONCLUSIONS: An experimental intraradicular biofilm model has been successfully established in pigs. Within the limitations of the study, subsonic or laser-activated irrigation demonstrated the best biofilm removal results in the pig system.

Effect of Carbohydrate-Electrolyte Solution Including Bicarbonate Ion Ad Libitum Ingestion on Urine Bicarbonate Retention during Mountain Trekking: A Randomized, Controlled Pilot Study.

We investigated whether bicarbonate ion (HCO3-) in a carbohydrate-electrolyte solution (CE+HCO3) ingested during climbing to 3000 m on Mount Fuji could increase urine HCO3- retention. This study was a randomized, controlled pilot study. Sixteen healthy lowlander adults were divided into two groups (six males and two females for each): a tap water (TW) group (0 kcal with no energy) and a CE+HCO3 group. The allocation to TW or CE+HCO3 was double blind. The CE solution contains 10 kcal energy, including Na+ (115 mg), K+ (78 mg), HCO3- (51 mg) per 100 mL. After collecting baseline urine and measuring body weight, participants started climbing while energy expenditure (EE) and heart rate (HR) were recorded every min with a portable calorimeter. After reaching a hut at approximately 3000 m, we collected urine and measured body weight again. The HCO3- balance during climbing, measured by subtracting the amount of urine excreted from the amount of fluid ingested, was -0.37 ± 0.77 mmol in the CE+HCO3, which was significantly higher than in the TW (-2.23 ± 0.96 mmol, p < 0.001). These results indicate that CE containing HCO3- supplementation may increase the bicarbonate buffering system during mountain trekking up to ~3000 m, suggesting a useful solution, at least, in the population of the present study on Mount Fuji.

Inhibition of the CXCL9-CXCR3 axis suppresses the progression of experimental apical periodontitis by blocking macrophage migration and activation.

Apical periodontitis (AP) is an acute or chronic inflammatory disease caused by complex interactions between infected root canal and host immune system. It results in the induction of inflammatory mediators such as chemokines and cytokines leading to periapical tissue destruction. To understand the molecular pathogenesis of AP, we have investigated inflammatory-related genes that regulate AP development. We found here that macrophage-derived CXCL9, which acts through CXCR3, is recruited by progressed AP. The inhibition of CXCL9 by a CXCR3 antagonist reduced the lesion size in a mouse AP model with decreasing IL-1ß, IL-6 and TNFα expression. The treatment of peritoneal macrophages with CXCL9 and LPS induced the transmigration and upregulation of osteoclastogenic cytokines such as IL-1ß, IL-6 and matrix metalloprotease 2, a marker of activated macrophages. This suggests that the CXCL9-CXCR3 axis plays a crucial role in the development of AP, mediated by the migration and activation of macrophages for periapical tissue destruction. Our data thus show that CXCL9 regulates the functions of macrophages which contribute to AP pathogenesis, and that blocking CXCL9 suppresses AP progression. Knowledge of the principal factors involved in the progression of AP, and the identification of related inflammatory markers, may help to establish new therapeutic strategies.

Combined stimuli of cold, hypoxia, and dehydration status on body temperature in rats: a pilot study with practical implications for humans.

OBJECTIVE: As human thermoregulatory responses to maintain core body temperature (Tcore) under multiple stressors such as cold, hypoxia, and dehydration (e.g., exposure to high-altitude) are varied, the combined effects of cold, hypoxia, and dehydration status on Tcore in rats were investigated. The following environmental conditions were constructed: (1) thermoneutral (24 °C) or cold (10 °C), (2) normoxia (21% O2) or hypoxia (12% O2), and (3) euhydration or dehydration (48 h water deprivation), resulted in eight environmental conditions [2 ambient temperatures (Ta) × 2 oxygen levels × 2 hydration statuses)]. Each condition lasted for 24 h. RESULTS: Normoxic conditions irrespective of hypoxia or dehydration did not strongly decrease the area under the curve (AUC) in Tcore during the 24 period, whereas, hypoxic conditions caused greater decreases in the AUC in Tcore, which was accentuated with cold and dehydration (Ta × O2 × hydration, P = 0.040 by three-way ANOVA). In contrast, multiple stressors (Ta × O2 × hydration or Ta × O2 or O2 × hydration or Ta × hydration) did not affect locomotor activity counts (all P > 0.05), but a significant simple main effect for O2 and Ta was observed (P < 0.001). Heat loss index was not affected by all environmental conditions (all P > 0.05). In conclusion, decreases in Tcore were most affected by multiple environmental stressors such as cold, hypoxia, and dehydration.

Performance of rice straw as mono- and co-feedstock of Ulva spp. for thalassic biogas production.

The seasonal availability of Ulva spp. (U) poses a problem for the continuous operation of thalassic (TH) biogas digesters. Hence, rice straw (RS) was tested as an alternative substrate because of its abundance in Asian countries. The anaerobic monodigestion (AMD) of RS was performed under freshwater (FW) and TH conditions to investigate the TH biogas production performance using terrestrial biomass. Biological hydrolysis (BH-P) and 3% NaOH (NaOH-P) pretreatments were employed to minimize the limitation of biomass hydrolysis in the methane fermentation process. The BH-P [FW = 62.2 ± 30.9 mLCH4 g-1VS (volatile solids); TH = 75.8 ± 5.7 mLCH4 g-1VS] of RS led to higher actual methane yield (AMY) than NaOH-P (FW = 15.8 ± 22.8 mLCH4 g-1VS; TH = 21.4 ± 4.2 mLCH4 g-1VS) under both conditions (P = 0.008), while AMY of FW BH-P was comparable (P = 0.182) to TH BH-P. Thus, TH and BH-P was applied to the anaerobic co-digestion (ACD) of U and RS of varying mixture ratios. All ACD set-ups resulted in higher AMY (25U:75RS = 107.6 ± 7.9 mLCH4 g-1VS, 50U:50RS = 130.3 ± 10.3 mLCH4 g-1VS, 75U:25RS = 121.7 ± 2.7 mLCH4 g-1VS) compared with 100% RS (75.8 ± 5.7 mLCH4 g-1VS) or 100% U (94.8 ± 6.8 mLCH4 g-1VS) alone. While the AMY of 50U:50RS was comparable to 75U:25RS (P = 0.181), it is significantly higher (P = 0.003) than its estimated methane yield (EMY; 85.3 mLCH4 g-1VS), suggesting a synergistic effect on ACD of U and RS under 50:50 ratio. The results show that RS can be used as an alternative mono-feedstock for TH biogas production, and a high AMY can be obtained when RS is used as co-feedstock with U.

Cadmium induces iron deficiency anemia through the suppression of iron transport in the duodenum.

Cadmium (Cd) is an environmental contaminant that triggers toxic effects in various tissues such as the kidney, liver, and lung. Cd can also cause abnormal iron metabolism, leading to anemia. Iron homeostasis is regulated by intestinal absorption. However, whether Cd affects the iron absorption pathway is unclear. We aimed to elucidate the relationship between the intestinal iron transporter system and Cd-induced iron deficiency anemia. C57BL/6J female and male mice, 129/Sv female mice, and DBA/2 female mice were given a single oral dose of CdCl2 by gavage. After 3 or 24 h, Cd decreased serum iron concentrations and inhibited the expression of iron transport-related genes in the duodenum. In particular, Cd decreased the levels of divalent metal transporter 1 and ferroportin 1 in the duodenum. In addition, human colon carcinoma Caco-2 cells were treated with CdCl2. After 72 h, Cd decreased the expression of iron transport-related factors in Caco-2 cells with a pattern similar to that seen in the murine duodenum. These findings suggest that Cd inhibits iron absorption through direct suppression of iron transport in duodenal enterocytes and contributes to abnormal iron metabolism.

Correction to: Genotoxicity assessment of titanium dioxide nanoparticle accumulation of 90 days in the liver of gpt delta transgenic mice.

[This corrects the article DOI: 10.1186/s41021-020-0146-3.].

Genotoxicity assessment of titanium dioxide nanoparticle accumulation of 90 days in the liver of gpt delta transgenic mice.

BACKGOUND: A variety of in vivo and in vitro studies to assess the genotoxicity of titanium dioxide nanoparticles (TiO2 NPs) have been reported, but the results are inconsistent. Recently, we reported that TiO2 NPs exhibit no genotoxic effects in the liver and erythrocytes during a relatively brief period following intravenous injection into mice. However, there is no information about long-term genotoxicity due to TiO2 NP accumulation in tissues. In this study, we investigated the long-term mutagenic effects of TiO2 NPs and the localization of residual TiO2 NPs in mouse liver after multiple intravenous injections. RESULTS: Male gpt delta C57BL/6 J mice were administered with various doses of TiO2 NPs weekly for 4 consecutive weeks. The long-term mutagenic effects on the liver were analyzed using gpt and Spi- mutation assays 90 days after the final injection. We also quantified the amount of titanium in the liver using inductively coupled plasma mass spectrometry and observed the localization of TiO2 NPs in the liver using transmission electron microscopy. Although TiO2 NPs were found in the liver cells, the gpt and Spi- mutation frequencies in the liver were not significantly increased by the TiO2 NP administration. CONCLUSIONS: These results clearly show that TiO2 NPs have no mutagenic effects on the liver, even though the particles remain in the liver long-term.

Reduction in Human Epidermal Langerhans Cells with Age Is Associated with Decline in CXCL14-Mediated Recruitment of CD14+ Monocytes.

The skin provides the first line of physical and immunological defense against environmental insults. However, the age-related changes in the immune function of human skin are unclear. Here, we investigated the age-related changes in epidermal Langerhans cells (LCs), which play a sentinel role in the initiation of the immune responses in the skin. We found a significant reduction in the number of epidermal LCs in sun-protected skin with age. Among the possible explanations for this reduction, the number of CD14+ CD207+ CCR6+ dermal-resident monocytes that can differentiate into epidermal LCs was markedly reduced with age (P = 0.0057). Among the chemokines that can recruit these cells into the skin, the expression of CXCL14 was significantly down-regulated in epidermal keratinocytes with age. In addition, we discovered that young skin recruited a significantly higher number of monocytic THP-1 cells compared with old skin ex vivo. This recruitment was blocked by CXCL14 neutralizing antibody and conversely promoted by CXCL14 treatment. Collectively, our findings indicate that decreased CXCL14-mediated recruitment of CD14+ monocytes in human skin results in the reduction of epidermal LCs with age, and CXCL14 may provide a therapeutic target for the prevention of age-related reduction in LCs.