TMEM16A channels mediate Ca-activated Cl (Cl) currents in vascular smooth muscle cells (VSMCs), and their activity is influenced by cytoskeletal dynamics. The present study examined the functional role of microtubules in...TMEM16A channels mediate Ca-activated Cl (Cl) currents in vascular smooth muscle cells (VSMCs), and their activity is influenced by cytoskeletal dynamics. The present study examined the functional role of microtubules in TMEM16A regulation. Treatment with microtubule polymerization inhibitors, colchicine and nocodazole, reduced plasma membrane localization of TMEM16A protein and TMEM16A-mediated Cl currents. Similar effects were observed in TMEM16A-expressing HEK293 cells, with IC values of 3.0 μM for colchicine and 0.6 μM for nocodazole. In contrast, acute application had no significant effect. These findings indicate that microtubules are required for maintaining the expression and functional activity of TMEM16A channels in VSMCs.
BACKGROUND AND OBJECTIVE: GPR35 is involved in the pathogenesis of colitis. However, because GPR35 is expressed in colonic epithelial and inflammatory/immune cells, its precise protective mechanisms remain unclear. We in...BACKGROUND AND OBJECTIVE: GPR35 is involved in the pathogenesis of colitis. However, because GPR35 is expressed in colonic epithelial and inflammatory/immune cells, its precise protective mechanisms remain unclear. We investigated the role of GPR35 in colitis, especially its relation to epithelial barrier function and inflammatory/immune responses. METHODS: We performed GPR35 knockout (KO) in a dextran sodium sulfate (DSS)-induced murine colitis model and elucidated the role of GPR35 through various experiments, including histological analysis, intestinal permeability, immunohistochemical staining, RT-qPCR, and western blotting. RESULTS: GPR35KO mice exhibited significantly exacerbated DSS-induced colitis, accompanied by upregulation of cytokines, compared with wild-type (WT) mice. An investigation using bone marrow (BM)-chimeric mice revealed that GPR35KO, which is expressed in both hematopoietic and non-hematopoietic cells, contributed to this exacerbation. GPR35KO mice showed significantly increased intestinal permeability compared with WT mice under normal conditions. Although no differences were observed in goblet cell number or epithelial proliferation between WT and GPR35KO mice, the expression levels of intercellular junction proteins were significantly lower in the normal colons of GPR35KO mice. Lipopolysaccharide-stimulated cytokine expression was significantly enhanced in BM-derived macrophages obtained from GPR35KO mice compared with WT mice. CONCLUSIONS: GPR35 contributes to colonic protection by regulating epithelial barrier function and inflammatory/immune responses.
Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating side effect of a number of anticancer drugs, like oxaliplatin, leading to chronic sensory hypersensitivity and neuropathic pain. This study i...Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating side effect of a number of anticancer drugs, like oxaliplatin, leading to chronic sensory hypersensitivity and neuropathic pain. This study investigated the efficacy of (2R,6R)-hydroxynorketamine ((2R,6R)-HNK), a metabolite of ketamine, in a rat model of CIPN induced by oxaliplatin. Rats treated with oxaliplatin developed long-lasting mechanical and thermal hypersensitivity, as assessed by the Von Frey test and the hot plate test, respectively. A single injection of (2R,6R)-HNK (30 mg/kg, s.c.) significantly reversed both mechanical and thermal hypersensitivity for up to 24 h. Furthermore, repeated treatment with (2R,6R)-HNK (30 mg/kg/day) for 7 days produced sustained analgesia on mechanical hypersensitivity that persisted up to 14 days after treatment cessation. In comparison, repeated duloxetine (15 mg/kg/day, s.c.) showed only a short-lasting reduction of thermal hypersensitivity and no effect on mechanical hypersensitivity. Locomotor activity was not affected by (2R,6R)-HNK treatment, although duloxetine caused a transient decrease. This is the first demonstration that (2R,6R)-HNK produced analgesia in a rat model of CIPN. The persistence of analgesia with repeated treatment and sustained effects following treatment cessation suggests that (2R,6R)-HNK may represent a promising new therapeutic strategy for the rapid and sustained relief of pain associated with CIPN.
Sepsis, a life-threatening organ dysfunction syndrome triggered by infection, is characterized by complex pathophysiology involving dysregulated inflammation, coagulation abnormalities, and mitochondrial dysfunction. Exc...Sepsis, a life-threatening organ dysfunction syndrome triggered by infection, is characterized by complex pathophysiology involving dysregulated inflammation, coagulation abnormalities, and mitochondrial dysfunction. Excessive activation of the NLRP3 inflammasome plays a pivotal role in sepsis progression. This study investigated the therapeutic effects and underlying mechanisms of protocatechuic aldehyde (PCA) in sepsis. Seventy-five potential PCA targets for sepsis were identified, with KEGG enrichment highlighting involvement in inflammatory and apoptotic pathways. PPI network analysis pinpointed TNF, IL-6, and IL-1β as key inflammatory targets. PCA dose-dependently suppressed IL-1β and TNF-α release in LPS/ATP-stimulated macrophages, reduced ASC speck formation and NLRP3-ASC interaction, and decreased mt-ROS production and TXNIP-NLRP3 co-localization. PCA also preserved mitochondrial network integrity by interacting with mitochondrial dynamics proteins DRP1 and MFN2, improving mitochondrial membrane potential and morphology. In LPS-induced septic mice, PCA significantly reduced serum IL-1β and TNF-α levels, improved survival rates, and downregulated NLRP3, pro-IL-1β, and cleaved-IL-1β expression in peritoneal macrophages. PCA alleviates inflammatory responses and organ damage in septic mice by inhibiting the mt-ROS/TXNIP/NLRP3 signaling axis and maintaining mitochondrial function, offering a promising natural therapeutic candidate for sepsis.
The development of targeted anti-epilepsy drugs is crucial, as 30 % of patients with epilepsy are resistant to current therapeutics. Transient receptor potential vanilloid 1 (TRPV1) channel antagonists have been demonstr...The development of targeted anti-epilepsy drugs is crucial, as 30 % of patients with epilepsy are resistant to current therapeutics. Transient receptor potential vanilloid 1 (TRPV1) channel antagonists have been demonstrated to suppress drug-induced epileptiform discharges (EDs) and seizures (ESs). Here, we investigated the correlation between the anti-epileptiform efficacy of AMG9810 and extracellular glutamate levels. The somatosensory cortices of male C57BL/6N mice were intracortically injected with penicillin G (PG: 200 IU, 1 μL/10 min), a seizure inducer that inhibits the GABA receptor. The mice were intracortically injected with AMG9810 (3 μM, 1 μL/10 min) either before or after PG administration. EDs, ESs, and glutamate levels were subsequently evaluated. The results of each experiment were compared between the vehicle and AMG9810-injected groups. AMG9810 injected after PG reduced glutamate levels and ED power, and there was a positive correlation between AMG9810 efficacy and these parameters. Injecting AMG9810 before PG injection decreased the increase in glutamate levels and development of EDs and ESs, with positive correlations observed among the three parameters. These findings suggest that TRPV1 antagonists suppress the development of EDs and ESs by decreasing extracellular glutamate levels, indicating that TRPV1 channels may represent a promising treatment option for epilepsy.
This study investigated whether tachykinin NK1 receptor antagonist aprepitant (APT) inhibits oxaliplatin (OXP)-induced cutaneous mast cell migration in mice. OXP-induced mast cell migration was inhibited by repeated oral...This study investigated whether tachykinin NK1 receptor antagonist aprepitant (APT) inhibits oxaliplatin (OXP)-induced cutaneous mast cell migration in mice. OXP-induced mast cell migration was inhibited by repeated oral administration of APT. OXP increased the expression of monocyte chemotactic protein-1 (MCP-1), stem cell factor (SCF), and interleukin-3 (IL-3), but not platelet-derived endothelial cell growth factor in the plantar skin. APT inhibited OXP-induced MCP-1, but not IL-3, expression. The expression of SCF tended to be inhibited by APT. These results suggest that APT attenuates OXP-induced cutaneous mast cell migration mainly by inhibiting the expression of MCP-1 and SCF.
Oxytocin (OXT) is a neuropeptide known for its anti-inflammatory and neuroprotective properties; however, its role in post-stroke recovery remains poorly defined. In this study, we investigated whether intranasal OXT adm...Oxytocin (OXT) is a neuropeptide known for its anti-inflammatory and neuroprotective properties; however, its role in post-stroke recovery remains poorly defined. In this study, we investigated whether intranasal OXT administration during the subacute phase of stroke improves neurological outcomes and modulates microglial responses. Male mice underwent permanent middle cerebral artery occlusion and received intranasal OXT (300 ng/g) or saline on days 3 and 5 post-stroke. Neurological function was assessed using the modified neurological severity score; infarct volume was evaluated through hematoxylin-eosin (HE) staining, and survival rates were monitored until day 7. Immunofluorescence was used to assess microglial polarization in the peri-infarct region. OXT-treated mice showed significantly greater functional improvement and higher survival rates than saline-treated controls. Infarct volume was significantly reduced, and microglial polarization was altered by OXT, with a decrease in pro-inflammatory M1-type markers and an increase in anti-inflammatory M2-type markers. These findings demonstrate that OXT promotes neurological recovery through anti-inflammatory and neuroprotective mechanisms. Given its feasibility as a non-invasive delivery method, intranasal OXT may offer a promising therapeutic approach to enhance post-stroke neurorepair.
Fracture is a common type of traumas and alternative therapies to boost bone fracture healing is necessary. The aim of this study is to elucidate the role of sulfasalazine in bone fracture healing by using MC3T3-E1 cells...Fracture is a common type of traumas and alternative therapies to boost bone fracture healing is necessary. The aim of this study is to elucidate the role of sulfasalazine in bone fracture healing by using MC3T3-E1 cells in vitro and murine femoral fracture model in vivo. Western blotting, flow cytometry, RNA sequencing, Calcein AM/PI staining, Alizarin-Red-S staining, ALP activity assay, transmission electron microscope, histological staining, immunohistochemistry, immunofluorescence and Surface plasmon resonance analysis were performed in this study. Sulfasalazine failed to elicit ferroptosis in osteoblasts within acceptable dose manner while promoted osteogenic differentiation. Furthermore, sulfasalazine was identified to inhibit inflammation by declination of inflammatory biomarkers. Besides, TNFα was verified as a potential downstream target for sulfasalazine and the adverse effect of TNFα on osteogenic differentiation could be largely salvaged by sulfasalazine due to direct binding between these two molecules. RNA-seq further implied decreased transcription of genes related to NF-κB pathway. Murine study showed sulfasalazine promotes fracture healing as evidenced by increased bone remodeling both histologically and radiologically. Overall, sulfasalazine accelerates osteogenic differentiation and promotes bone healing by direct binding to and thus inhibiting TNFα, which subsequently suppresses NF-κB signaling. Therefore, sulfasalazine shows a promising outcome for the treatment of bone fracture.
Object recognition memory encourages animals to distinguish between new and known objects, supported by neural activity in the hippocampus, prefrontal cortex, and perirhinal cortex. Theanine, a non-proteinogenic amino ac...Object recognition memory encourages animals to distinguish between new and known objects, supported by neural activity in the hippocampus, prefrontal cortex, and perirhinal cortex. Theanine, a non-proteinogenic amino acid derivative from green tea leaves, enhances object recognition memory in rats through facilitated neurogenesis. Although the cellular mechanism for the theanine-enhanced object recognition memory has been elucidated to some extent, physiological evidence still remains unclear. To tackle this issue, we chronically fed mice with theanine (or tap water) for three weeks, implanted electrodes into the hippocampus and frontal cortex, both of which are responsible for object recognition memory. We then recorded the local field potentials from the two regions during the novel object recognition task, evaluated the memory performance, and broke down the neural signals in the hippocampus and frontal cortex into delta, theta, beta, low gamma, and high gamma frequency bands. The memory performance of theanine-treated mice was higher than that of vehicle-treated mice. We also found that theta oscillations in the frontal cortex and beta and low gamma oscillations in the hippocampus in theanine-treated mice were simultaneously enhanced for familiar objects. These results shed light on the new physiological underpinnings of object recognition memory enhanced by exogenous substances.
Smoking of combustible cigarettes is a risk factor for cardiovascular disease. Heated tobacco products (HTPs) have recently increased in use due to their perceived lower toxicity compared with combustible cigarettes, yet...Smoking of combustible cigarettes is a risk factor for cardiovascular disease. Heated tobacco products (HTPs) have recently increased in use due to their perceived lower toxicity compared with combustible cigarettes, yet their direct effects on cardiomyocytes remain unclear. In the present study, we compared the effects of nicotine- and tar-free cigarette smoke extracts (CSE) from two HTPs ('HTP-1' and 'HTP-2') and a combustible reference cigarette (RF) on cultured neonatal rat ventricular myocyte. All CSEs reduced cell viability and the spontaneous beating rate, with toxicity ranked as RF > HTP-2 > HTP-1. HTP-2 and RF also induced intracellular Ca-overload, contractile dysfunction, and mitochondrial reactive oxygen species production, whereas HTP-1 did not. Mitochondrial respiration and ATP production were suppressed by all CSEs, while glycolysis was upregulated only by HTP-2 and RF, indicating different metabolic alterations. Acrolein, a shared toxicant in all products, also reduced cell viability, suggesting its involvement in CSE-induced cardiotoxicity. In summary, we revealed that HTPs, like combustible cigarettes, exhibit direct cardiomyocyte toxicity, but the underlying mechanisms appear to differ between different cigarette products with regard to abnormal Ca regulation and metabolic inhibition. These findings raise concern regarding the cardiac safety of HTPs.
Diabetic nephropathy (DN) is a leading cause of chronic kidney disease (CKD), affecting nearly one-third of CKD patients. As CKD advances, it may progress to end-stage renal disease, necessitating dialysis or transplanta...Diabetic nephropathy (DN) is a leading cause of chronic kidney disease (CKD), affecting nearly one-third of CKD patients. As CKD advances, it may progress to end-stage renal disease, necessitating dialysis or transplantation. Hyperglycemia-driven metabolic and hemodynamic disturbances contribute to oxidative stress, inflammation, and fibrosis. Since current treatments remain insufficient, novel therapeutic strategies are urgently needed to halt DN progression. Stachybotrys microspora triprenyl phenols (SMTPs), the focus of our research, exhibit anti-inflammatory properties and have shown therapeutic potential in various disease models. We aimed to evaluate the efficacy of SMTP-27 in a DN mouse model. DN was induced by removing the right kidney of db/db mice. The efficacy of SMTP-27 was determined by evaluating the renal function using urine and serum samples and morphological assessment of the kidney tissues. For deciphering the mechanism of action of SMTP-27, markers associated with inflammatory signaling pathways in the kidney were detected. SMTP-27 (0.03, 0.3, 3, 30 mg/kg) dose-dependently improved the renal function. In addition, it improved the mesangial matrix overproduction, podocyte injury, and renal tubule injury and exhibited anti-inflammatory activity in the kidneys of mice with DN. These results indicate the potential of SMTP-27 as a novel therapeutic strategy for DN.
Despite being the most common adult heart valve disease in developed countries, no medicinal treatment exists for calcific aortic valve stenosis (CAS). We previously demonstrated that tumor necrosis factor (TNF)-α promot...Despite being the most common adult heart valve disease in developed countries, no medicinal treatment exists for calcific aortic valve stenosis (CAS). We previously demonstrated that tumor necrosis factor (TNF)-α promotes aortic valve calcification (AVC) via the bone morphogenic protein (BMP) 2-alkaline phosphatase (ALP) pathway. In the present study, we aimed to investigate the effects of Kampo, a traditional Japanese herbal medicine, on TNF-α-induced AVC involving CAS progression. We confirmed that Oren-gedoku-to (OGT, 10-100 μg/mL) strongly and dose-relatedly inhibited HAVIC calcification induced by TNF-α (30 ng/mL). OGT significantly inhibited TNF-α-induced BMP2 expression, p65 NF-κB phosphorylation, and ALP activation in HAVICs. Notably, two crude drugs from OGT [Coptis rhizome (CR), and Phellodendron bark (PB)] exhibited inhibitory effects akin to those of OGT. Berberine, mainly contained in CR and PB, also inhibited TNF-α induced HAVIC calcification, BMP2 expression, and p65 NF-κB phosphorylation. Further, OGT significantly prevented accelerated AVC in spontaneously hypertensive rats in vivo. Our results suggest that OGT and its component, berberine, can effectively prevent AVC acceleration both in vitro and in vivo.
Inwardly rectifying potassium 4.1 (Kir4.1) channels are predominantly expressed in astrocytes and considered to be involved in the pathogenesis of brain diseases, including depression and epilepsy. In the present study,...Inwardly rectifying potassium 4.1 (Kir4.1) channels are predominantly expressed in astrocytes and considered to be involved in the pathogenesis of brain diseases, including depression and epilepsy. In the present study, we evaluated the effects of Kir4.1 channel inhibitors, VU0134992 and quinacrine, on lipopolysaccharide (LPS)-induced cognitive impairment to clarify the role of Kir4.1 channels in controlling cognitive functions. Male BALB/c mice were treated with LPS, with or without Kir4.1 channel inhibitors, for 7 days. Animals were then subjected to novel object recognition (NOR) and rota-rod tests. Immunohistochemical analyses of glia fibrillary acid protein (GFAP) and neuronal nuclei (NeuN) were also performed. Treatment of LPS clearly showed cognitive impairment in the NOR test, which accompanied elevated GFAP- and reduced NeuN-immunoreactivity in hippocampal CA1 and CA3 regions. VU0134992 and quinacrine significantly ameliorated LPS-induced cognitive impairment without affecting rota-rod performance. In addition, both Kir4.1 channel inhibitors suppressed LPS-induced astrocyte activation and attenuated neuronal damage in CA1 and CA3 regions. Furthermore, combined treatments of ANA-12, a TrkB receptor antagonist, with VU0134992 suppressed the ameliorative effects of VU0134992 on cognitive impairment and hippocampal neuronal damage. These results suggest that blockade of astrocytic Kir4.1 channels ameliorates neuroinflammatory cognitive impairment via BDNF/TrkB signaling pathway.
Acute kidney injury is associated with not only high morbidity in the acute phase but also the development of chronic kidney disease (CKD). Recently, we found that suppression of secreted protein acidic and rich in cyste...Acute kidney injury is associated with not only high morbidity in the acute phase but also the development of chronic kidney disease (CKD). Recently, we found that suppression of secreted protein acidic and rich in cysteine (SPARC) exhibits renoprotective effects in acute ischemia/reperfusion (I/R) injury. The present study investigated the hypothesis that temporal suppression of SPARC in the early stages of I/R-injury might lead to the prevention of renal injury in the chronic phase. The left renal pedicle of male BALB/c mice was occluded for 45 min after right uninephrectomy and subsequently reperfused for 28 days. Small interfering RNA (siRNA) targeting SPARC was injected intravenously 1 day before and 3 days after I/R. Histological assessment revealed that SPARC knockdown by siRNA attenuated tubular injury, tubulointerstitial fibrosis, and the overexpression of 4-hydroxynonenal, a marker of lipid peroxidation. I/R-induced overexpression of a major source of superoxide NADPH oxidase, tumor necrosis factor-α, and matrix metalloproteinase-9 was suppressed by siRNA targeting SPARC. Treatment with siRNA targeting SPARC reduced the expression of a disintegrin and metalloproteinase with thrombospondin type 1 motif (ADAMTS1), which colocalizes with SPARC. In conclusion, SPARC might be a potential therapeutic target for preventing CKD development following acute I/R injury.
Lactucin is a natural sesquiterpene lactone isolated from Cichorium glandulosum Boiss. et Huet (CG) has unique biological and pharmaceutical properties. This study was designed to investigate the mechanisms by which Lact...Lactucin is a natural sesquiterpene lactone isolated from Cichorium glandulosum Boiss. et Huet (CG) has unique biological and pharmaceutical properties. This study was designed to investigate the mechanisms by which Lactucin inhibits lipid accumulation in free fatty acid (FFA)-treated HepG2 cells. We demonstrated that Lactucin exerts a protective effect against hepatic steatosis in vitro. In FFA-induced HepG2 cells, Lactucin effectively ameliorated lipid accumulation, oxidative stress, and mitochondrial dysfunction. Mechanistically, we showed that activation of AMP-activated protein kinase (AMPK) and hormone-sensitive lipase (HSL) by Lactucin promoted lipolysis and further enhanced fatty acid β-oxidation (FAβO) by increasing the activity of FAβO-related enzymes, thereby contributing to the reduction of lipid accumulation. Moreover, Lactucin activated autophagy and modulated the AMPK/mammalian target of rapamycin (mTOR) signaling pathway. Notably, we found that Lactucin-induced autophagy played a significant role in decreasing lipid droplet accumulation, suggesting it may be a key underlying mechanism. These findings, for the first time, provide new insights into the pharmaceutical mechanism of Lactucin in protecting against nonalcoholic fatty liver disease (NAFLD).
BACKGROUND: Neuroinflammation contributes to cognitive deficits in status epilepticus (SE). The lncRNA Mir155hg has been identified as a key regulator of inflammation, but its role in SE remains unclear. METHODS: Mir155h...BACKGROUND: Neuroinflammation contributes to cognitive deficits in status epilepticus (SE). The lncRNA Mir155hg has been identified as a key regulator of inflammation, but its role in SE remains unclear. METHODS: Mir155hg was knocked down using the adeno-associated virus (AAV) in the rat models of SE. Cognitive function and neuronal damage were assessed using Morris Water Maze and Nissl staining. Inflammatory cytokines (TNF-α, IL-1β) and NF-κB pathway activity were measured by Western blot. Mechanistic insights into Mir155hg-mediated NF-κB regulation were investigated via dual-luciferase assays and co-immunoprecipitation analysis. RESULTS: Our findings demonstrated that elevated level of Mir155hg was positively correlated with upregulation of TNF-α and IL-1β both in vivo and in vitro. Knockdown of Mir155hg reduced hippocampal inflammation and NF-κB activation. Mechanistically, Mir155hg acted as a competing endogenous RNA to sequester miR-155, thereby suppressing the expression of Socs1, an E3 ligase targeting NF-κB p65 for degradation. Co-immunoprecipitation analysis confirmed the interaction between NF-κB p65 and Socs1. CONCLUSIONS: Mir155hg exacerbates SE-related neuroinflammation via the miR-155/Socs1/NF-κB axis. Targeting this pathway may mitigate SE-induced neuronal injury and cognitive deficits.
Habash M, Almansour ZH, Al-Akeel RK
… +11 more, Ismail MB, Althumairy D, Zahra HA, Abd-Elhamid TH, Ghogar OM, Ali MM, Abd El-Aziz MK, Sharab EI, Khader HF, Mahmoud AR, Ali FEM
Obstructive nephropathy is a chronic condition that causes progressive kidney damage due to inflammation, oxidative stress, necroptosis, and fibrosis. The present study aimed to evaluate the potential chemopreventive eff...Obstructive nephropathy is a chronic condition that causes progressive kidney damage due to inflammation, oxidative stress, necroptosis, and fibrosis. The present study aimed to evaluate the potential chemopreventive effect of infliximab (TNF-α inhibitor) or umbelliferone (UMB, a natural antioxidant) individually and together to treat unilateral ureter ligation (UUL)-induced interstitial renal fibrosis in rats. The therapeutic effects were assessed through renal function biomarkers, histopathology, fibrosis, inflammation, oxidative stress, and necroptosis. UUL-induced renal injury led to increased serum biomarkers (urea, creatinine, uric acid), inflammation markers (TNF-α, NF-κB, IKK), oxidative stress (elevated NADPH oxidase and MDA, reduced Nrf2/HO-1, GSH, SOD), and necroptosis (upregulated RIPK1/RIPK3/p-RIPK3/MLKL/caspase-8), with substantial collagen deposition and fibrosis. Treatment with infliximab and UMB showed preventive effects by suppressing TNF-α signaling, reducing oxidative stress, and boosting antioxidant defense. Combined therapy provided superior results by downregulating TNF-α/RIPK/Caspase-8 pathways, enhancing Nrf2/HO-1 activity, reducing fibrosis, and restoring renal structure and function. Computational docking confirmed the ability of UMB to interact with TNF-α and RIPK3/MLKL binding sites. In conclusion, the combination of infliximab and UMB offers a promising multi-targeted approach to treat obstructive nephropathy and related chronic kidney diseases and highlights its potential to modulate key pathways involved in kidney fibrosis.
Filaggrin (FLG) is one of the major components expressed in terminally differentiated keratinocytes and critical for skin barrier functions. It is known that reduced FLG expression causes skin barrier dysfunctions and re...Filaggrin (FLG) is one of the major components expressed in terminally differentiated keratinocytes and critical for skin barrier functions. It is known that reduced FLG expression causes skin barrier dysfunctions and results in atopic dermatitis (AD). Restoring FLG expression therefore may serve as an effective therapeutic strategy against AD. Using normal human epidermal keratinocyte (NHEK), we identified a phenylalanine amide derivative, termed Compound 8.1, that promotes expression of FLG and other skin barrier-related genes in NHEKs. Gene expression profiling by microarray suggested that Compound 8.1 promotes FLG expression through activation of the aryl hydrocarbon receptor (AHR). Interestingly, compared to a typical AHR activator, FICZ (6-Formylindolo[3,2-b]carbazole), Compound 8.1 preferentially upregulated the expression of genes related to keratinocyte differentiation and skin barrier function in an AHR-dependent manner, but induced a conventional AHR target gene involved in cellular toxicity, CYP1A1, to a significantly lesser extent. Structure-activity relationship analysis further demonstrates that the structural modification of Compound 8.1 could dissociate induction of skin barrier-related gene expression from CYP1A1-dependent metabolism of xenobiotics in AHR actions. Together, our results suggest that Compound 8.1 serves as a prototype compound for developing novel AHR-activating drugs to treat skin barrier dysfunctions without toxicity.
The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway is a major cellular defense mechanism against oxidative stress through the induction of antioxidant proteins. Chemical ind...The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway is a major cellular defense mechanism against oxidative stress through the induction of antioxidant proteins. Chemical inducers of Nrf2 often exhibit anti-inflammatory properties. TPNA10168, originally identified as an Nrf2-ARE activator, has previously been shown to attenuate interferon-γ-induced inflammatory responses in BV-2 microglial cells in an Nrf2-independent manner. However, its anti-inflammatory effects on primary microglia remain unclear. In this study, TPNA10168 significantly suppressed the lipopolysaccharide (LPS)-induced expression of inflammatory genes, including tumor necrosis factor-α, interleukin (IL)-1β, and IL-6, in primary microglia. The anti-inflammatory effects of TPNA10168 persisted even after Nrf2 knockdown. Mechanistic analysis revealed that TPNA10168 inhibited LPS-induced phosphorylation of extracellular signal-regulated kinase, p38 mitogen-activated protein kinase, and nuclear factor-κB (NF-κB) p65 without affecting NF-κB nuclear translocation. These findings indicate that TPNA10168 attenuates microglial activation by inhibiting proinflammatory signaling pathways, in part through Nrf2-independent pathways, and is a promising compound for modulating neuroinflammation.