Langerhans cells are critical in epicutaneous sensitization with protein antigen via thymic stromal lymphopoietin receptor signaling.

Background: The clarification of cutaneous dendritic cell subset and the role of thymic stromal lymphopoietin (TSLP) signaling in epicutaneous sensitization with protein antigens, as in the development of atopic dermatitis, is a crucial issue. Objectives: Because TSLP is highly expressed in the vicinity of Langerhans cells (LCs), we sought to clarify our hypothesis that LCs play an essential role in epicutaneous sensitization with protein antigens through TSLP signaling. Methods: By using Langerin-diphtheria toxin receptor knock-in mice and human Langerin-diphtheria toxin A transgenic mice, we prepared mice deficient in LCs. We also prepared mice deficient in TSLP receptors in LCs by using TSLP receptor–deficient mice with bone marrow chimeric technique. We applied these mice to an ovalbumin (OVA)-induced epicutaneous sensitization model. Results: Upon the epicutaneous application of OVA, conditional LC depletion attenuated the development of clinical manifestations as well as serum OVA-specific IgE increase, OVA-specific T-cell proliferation, and IL-4 mRNA expression in the draining lymph nodes. Consistently, even in the steady state, permanent LC depletion resulted in decreased serum IgE levels, suggesting that LCs mediate the T[H]2 local environment. In addition, mice deficient in TSLP receptors on LCs abrogated the induction of OVA-specific IgE levels upon epicutaneous OVA sensitization. Conclusion: LCs initiate epicutaneous sensitization with protein antigens and induce T[H]2-type immune responses via TSLP signaling

A single nucleotide polymorphism in 3′-untranslated region contributes to the regulation of toll-like receptor 4 translation

We have previously shown that a single nucleotide polymorphism rs11536889 in the 3′-untranslated region (UTR) of TLR4 was associated with periodontitis. In this study the effects of this single nucleotide polymorphism on Toll-like receptor (TLR) 4 expression were investigated. Monocytes from subjects with the C/C genotype expressed higher levels of TLR4 on their surfaces than those from subjects with the other genotypes. Peripheral blood mononuclear cells (PBMCs) from the C/C and G/C subjects secreted higher levels of IL-8 in response to lipopolysaccharide (LPS), a TLR4 ligand, than the cells from the G/G subjects. However, there was no significant difference in TLR4 mRNA levels in PBMCs from the subjects with each genotype. After stimulation with tripalmitoylated CSK 4 (Pam 3CSK 4), TLR4 mRNA levels increased in PBMCs from both the C/C and G/G subjects, whereas TLR4 protein levels increased in PBMCs from the C/C but not G/G subjects. Transient transfection of a series of chimeric luciferase constructs revealed that a fragment of 3′-UTR containing rs11536889 G allele, but not C allele, suppressed luciferase activity induced by LPS or IL-6. Two micro- RNAs, hsa-miR-1236 and hsa-miR-642a, were predicted to bind to rs11536889 G allele. Inhibition of these microRNAs reversed the suppressed luciferase activity. These microRNA inhibitors also up-regulated endogenous TLR4 protein on THP-1 cells (the G/G genotype) after LPS stimulation. Furthermore, mutant microRNAs that bind to the C allele inhibited the luciferase activity of the construct containing the C allele. These results indicate that genetic variation of rs11536889 contributes to translational regulation of TLR4, possibly by binding to microRNAs

Protective effect of 3-hydroxybutyrate against endoplasmic reticulum stress-associated vascular endothelial cell damage induced by low glucose exposure.

The aim of this study was to elucidate the mechanism by which severe hypoglycemia accelerates vascular complications. Furthermore, we assessed the possible protective effect of ketone bodies against the endothelial cell damage caused by glucose deficiency.Human umbilical vein endothelial cells (HUVECs) were cultured at a glucose level of either 0.56 or 5.6 mmol/L with or without 3-hydroxybutyrate (3-HB) supplementation. Cell viability was assessed with a CCK-8 assay and a lactate dehydrogenase (LDH) release assay. The activity of caspases was measured using fluorogenic substrates. The expression of genes associated with endothelial cell function and endoplasmic reticulum (ER) stress was evaluated by real-time quantitative PCR. Protein levels of ER stress-related molecules were assessed by Western blotting.Culture of HUVECs in low-glucose medium for 24 or 48 h resulted in reduction of cell viability accompanied by activation of caspase-3/7 and caspase-8. The addition of a pan caspase inhibitor attenuated the cell death. After incubation in the low-glucose medium, we found reduced mRNA and protein levels of endothelial nitric oxide synthase. ER stress responses mediated by phosphorylation of protein kinase RNA-like ER kinase (PERK) and cleavage of activating transcription factor 6 (ATF6) were augmented, but X-box binding protein 1 (Xbp1) splicing was reduced. Most of these responses to glucose deficiency were significantly attenuated by supplementation with 3-HB.These observations showed that exposure to low glucose induces ER stress, caspase activation, endothelial cell dysfunction and cell death. The beneficial effects of 3-HB shown in this study suggest that hypoketonemic severe hypoglycemia induced by insulin injections or insulin secretagogue administration may be more harmful than hyperketonemic severe hypoglycemia

Prior antihistamine agent successfully impaired cutaneous adverse reactions to COVID‐19 vaccine

Abstract The coronavirus disease 2019 (COVID‐19) vaccine is positively changing the health crises of this pandemic and is currently essential to overcome the COVID‐19 pandemic. The vaccine shows high efficacy against the infection and impairs the severity of symptoms. However, this vaccination is associated with concerns, such as vaccine‐associated adverse reactions, which are currently highlighted issues for clinicians. We experienced two cases of mild cutaneous adverse reaction following COVID‐19 vaccine administration, which was successfully controlled by prior administration of the antihistamine agent fexofenadine 3 days before COVID‐19 vaccination for 7 days

Scavenging of reactive oxygen species by astaxanthin inhibits epithelial–mesenchymal transition in high glucose-stimulated mesothelial cells

<div><p>Background</p><p>High glucose concentrations influence the functional and structural development of the peritoneal membrane. We previously reported that the oral administration of astaxanthin (AST) suppressed peritoneal fibrosis (PF) as well as inhibited oxidative stress, inflammation, and epithelial–mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) in a chlorhexidine-induced PF rat model. This suggests that oxidative stress induction of EMT is a key event during peritoneal damage. The present study evaluated the therapeutic effect of AST in suppressing EMT, in response to glucose-induced oxidative stress.</p><p>Methods</p><p>Temperature-sensitive mesothelial cells (TSMCs) were cultured in the presence or absence of AST and then treated with 140 mM glucose for 3 or 12 hours. Expression levels of TNF-α, TGF-β, and VEGF were determined at the mRNA and protein levels, and nuclear factor kappa B (NF-κB) activity was evaluated. We measured NO₂⁻/NO₃⁻ concentrations in cellular supernatants and determined 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in mitochondrial and nuclear DNA. The expressions of E-cadherin and alpha-smooth muscle actin (α-SMA) were evaluated by double immunofluorescence and protein levels.</p><p>Results</p><p>High glucose concentrations induced overproduction of reactive oxidative species (ROS), increasing 8-OHdG mitochondrial DNA and cytokine levels. The NF-κB pathway was activated in response to high glucose concentrations, whereas <i>de novo</i> α-SMA expression was observed with decreased E-cadherin expression. AST treatment attenuated ROS production, inflammatory cytokine production, NF-κB activation, and EMT.</p><p>Conclusion</p><p>The findings of the present study indicate that AST may have an anti-EMT effect due to anti-oxidative and anti-inflammatory activities by scavenging glucose-induced ROS from mitochondria in PMCs. AST may be an efficacious treatment for PF.</p></div

Effect of high glucose stimulation, AST, and AA to TSMCs as for ROS.

<p>(A) NO₂⁻/NO₃⁻ concentration in medium supernatant of each group. (B) Intracellular ROS levels of each group. (C) 8-OHdG ratio in mitochondrial DNA of each group. (D) 8-OHdG ratio in nuclear DNA of each group. AST concentration: 5 μM, AA concentration: 100 μM. NS: no significant change. *: p < 0.05. **: p < 0.01. ***: p < 0.0005. ****: p < 0.0001. Error bars represent SD. (E) ROS fluorescence of each group (1) C3h group, (2) C12h group, (3) AST3h group, (4) AST12h group, (5) AA3h group, (6) AA12h group, (7) G3h group, (8) G12h group, (9) AST-G3h group, (10) AST-G12h group, (11) AA-G3h group, and (12) AA-G12h group. Fluorescence solution was 2′, 7′-dichlorodihydrofluorescin diacetate (DCFH-DA).</p