Ginkgetin exhibits antifibrotic effects by inducing hepatic stellate cell apoptosis via STAT1 activation.

Liver fibrosis affects approximately 800 million patients worldwide, with over 2 million deaths each year. Nevertheless, there are no approved medications for treating liver fibrosis. In this study, we investigated the impacts of ginkgetin on liver fibrosis and the underlying mechanisms. The impacts of ginkgetin on liver fibrosis were assessed in mouse models induced by thioacetamide or bile duct ligation. Experiments on human LX-2 cells and primary mouse hepatic stellate cells (HSCs) were performed to explore the underlying mechanisms, which were also validated in the mouse models. Ginkgetin significantly decreased hepatic extracellular matrix deposition and HSC activation in the fibrotic models induced by thioacetamide (TAA) and bile duct ligation (BDL). Beneficial effects also existed in inhibiting hepatic inflammation and improving liver function. In vitro experiments showed that ginkgetin markedly inhibited HSC viability and induced HSC apoptosis dose-dependently. Mechanistic studies revealed that the antifibrotic effects of ginkgetin depend on STAT1 activation, as the effects were abolished in vitro after STAT1 silencing and in vivo after inhibiting STAT1 activation by fludarabine. Moreover, we observed a meaningful cross-talk between HSCs and hepatocytes, in which IL-6, released by ginkgetin-induced apoptotic HSCs, enhanced hepatocyte proliferation by activating STAT3 signaling. Ginkgetin exhibits antifibrotic effects by inducing HSC apoptosis via STAT1 activation and enhances hepatocyte proliferation secondary to HSC apoptosis via the IL-6/STAT3 pathway.

GADD45A regulates subcutaneous fat deposition and lipid metabolism by interacting with Stat1.

BACKGROUND: Obesity, characterized by excessive white adipose tissue expansion, is associated with several metabolic complications. Identifying new adipogenesis regulators may lead to effective therapies for obesity-induced metabolic disorders. RESULTS: Here, we identified the growth arrest and DNA damage-inducible A (GADD45A), a stress-inducible histone-folding protein, as a novel regulator of subcutaneous adipose metabolism. We found that GADD45A expression was positively correlated with subcutaneous fat deposition and obesity in humans and fatty animals. In vitro, the gain or loss function of GADD45A promoted or inhibited subcutaneous adipogenic differentiation and lipid accumulation, respectively. Using a Gadd45a-/- mouse model, we showed that compared to wild-type (WT) mice, knockout (KO) mice exhibited subcutaneous fat browning and resistance to high-fat diet (HFD)-induced obesity. GADD45A deletion also upregulated the expression of mitochondria-related genes. Importantly, we further revealed that the interaction of GADD45A with Stat1 prevented phosphorylation of Stat1, resulting in the impaired expression of Lkb1, thereby regulating subcutaneous adipogenesis and lipid metabolism. CONCLUSIONS: Overall, our results reveal the critical regulatory roles of GADD45A in subcutaneous fat deposition and lipid metabolism. We demonstrate that GADD45A deficiency induces the inguinal white adipose tissue (iWAT) browning and protects mice against HFD-induced obesity. Our findings provide new potential targets for combating obesity-related metabolic diseases and improving human health.

The role of Kupffer cell activation in immune liver damage induced by trichloroethylene associated with the IFN-γ/STAT1 signaling pathway.

Trichloroethylene (TCE) is a metal detergent commonly used in industry that can enter the human body through the respiratory tract and skin, causing occupational medicamentosa-like dermatitis due to TCE (OMDT) and multiple organ damage, including liver failure. However, the pathogenesis of liver injury remains unclear. Kupffer cells (KCs) are important tissue macrophages in the body because the polarization of KCs plays a crucial role in immune-mediated liver injury. However, the mechanism of KCs polarization in TCE-induced immune liver injury has not been thoroughly elucidated. In this study, we investigated the effect of TCE-induced KCs polarization on liver function and signal transduction pathways using the TCE sensitization model developed by our group. BALB/c mouse skin was exposed to TCE for sensitization, and an increase in the expression of M1 macrophage-specific markers (CD16/CD32, iNOS), M1 macrophage-specific cytokines IL-1ß, and IFN-γ, P-JAK-1 and P-STAT1 levels were also found to be dramatically increased. When using low doses of gadolinium trichloride (GdCl3), the expression of these proteins and mRNA was significantly reduced. This phenomenon indicates that GdCl3 blocks TCE-induced polarization of KCs and suggests that the IFN-γ/STAT1 signaling pathway may be involved in the polarization process of KCs. These findings clarify the relationship between the polarization of KCs and immune liver injury and highlight the importance of further study of immune-mediated liver injury in TCE-sensitized mice.

Cadmium exposure induces necroptosis of porcine spleen via ROS-mediated activation of STAT1/RIPK3 signaling pathway.

Cadmium (Cd), a heavy metal, is used in a wide range of applications, such as plastics, electroplating process, electronics, and so forth. Due to its bioaccumulation ability, Cd can contaminate soil, water, air and food. To determine the effect of Cd exposure on the necroptosis in pig spleen and its mechanistic investigation, we constructed a model in pigs by feeding them food containing 20 mg/kg Cd. In this study, we analyzed the effects of Cd exposure on pig spleen through HE staining, Quantitative real-time PCR (qRT-PCR), Western blot (WB), and principal component analysis (PCA). Results show that Cd exposure can destroy the structure and function of pig spleen, which is closely related to necroptosis. Further results show that Cd exposure can induce necroptosis through ROS-mediated activation of Signal transducer and activator of transcription 1/Receptor-Interacting Serine/Threonine-Protein Kinase 3 (STAT1/RIPK3) signaling pathway in pig spleen. Additionally, Cd exposure also can affect the stability of mitochondrial-associated endoplasmic reticulum membrane (MAMs) structure, which also contributes to the process of necroptosis. Our study provides insights into the physiological toxicity caused by Cd exposure.

Ultrasound reduces inflammation by modulating M1/M2 polarization of microglia through STAT1/STAT6/PPARγ signaling pathways.

INTRODUCTION: Activated microglia can be polarized to the pro-inflammatory M1 phenotype and the anti-inflammatory M2 phenotype. Low-intensity pulsed ultrasound (LIPUS) can attenuate pro-inflammatory responses in activated microglia. OBJECTIVE: This study aimed to investigate the effects of LIPUS on M1/M2 polarization of microglial cells and the regulatory mechanisms associated with signaling pathways. METHODS: BV-2 microglial cells were stimulated by lipopolysaccharide (LPS) to an M1 phenotype or by interleukin-4 (IL-4) to an M2 phenotype. Some microglial cells were exposed to LIPUS, while others were not. M1/M2 marker mRNA and protein expression were measured using real-time polymerase chain reaction and western blot, respectively. Immunofluorescence staining was performed to determine inducible nitric oxide synthase (iNOS)-/arginase-1 (Arg-1)- and CD68-/CD206-positive cells. RESULTS: LIPUS treatment significantly attenuated LPS-induced increases in inflammatory markers (iNOS, tumor necrosis factor-α, interleukin-1ß, and interleukin-6) as well as the expression of cell surface markers (CD86 and CD68) of M1-polarized microglia. In contrast, LIPUS treatment significantly enhanced the expression of M2-related markers (Arg-1, IL-10, and Ym1) and membrane protein (CD206). LIPUS treatment prevented M1 polarization of microglia and enhanced or sustained M2 polarization by regulating M1/M2 polarization through the signal transducer and activator of transcription 1/STAT6/peroxisome proliferator-activated receptor gamma pathways. CONCLUSIONS: Our findings suggest that LIPUS inhibits microglial polarization and switches microglia from the M1 to the M2 phenotype.

MALAT1 knockdown alleviates the pyroptosis of microglias in diabetic cerebral ischemia via regulating STAT1 mediated NLRP3 transcription.

BACKGROUND: Dysregulated long non-coding RNAs participate in the development of diabetic cerebral ischemia. This study aimed to investigate the underlying mechanism of lncRNA MALAT1 in diabetic cerebral ischemia. METHOD: Middle cerebral artery occlusion (MCAO) was performed to establish diabetic cerebral I/R in vivo. TTC and neurological deficits assessment were performed to assess cerebral ischemic injury. LDH was conducted to detect cytotoxicity. RT-qPCR and western blotting assays were applied to determine mRNA and protein expression. Flow cytometry was performed to detect the pyroptosis of BV2 cells. Immunofluorescence and FISH were conducted for subcellular localization of MALAT1 and STAT1. ELISA was performed to determine cytokine release. Dual luciferase reporter, RIP, and ChIP assays were used to validate the interaction between STAT1 and MALAT1/NLRP3. Diabetes aggravated cerebral injury in vivo and in vitro. Diabetic cerebral ischemia induced inflammatory response and inflammation-induced cell pyroptosis. RESULT: MALAT1 was overexpressed in diabetic cerebral ischemia models in vivo and in vitro. However, knockdown of MALAT1 suppressed inflammatory response and the pyroptosis of BV2 cells. Moreover, MALAT1 interacted with STAT1 to transcriptionally activate NLRP3. Knockdown of STAT1 significantly reversed the effects of MALAT1. Furthermore, STAT1 promotes the MALAT1 transcription. MALAT1 interacts with STAT1 to promote the pyroptosis of microglias induced by diabetic cerebral ischemia through activating NLRP3 transcription. CONCLUSION: Thus, knockdown of MALAT1 may be a potential promising therapy target for diabetic cerebral ischemia.

Unique aspects of IFN-γ/STAT1 signaling in neurons.

The IFN-γ/STAT1 immune signaling pathway impacts many homeostatic and pathological aspects of neurons, beyond its canonical role in controlling intracellular pathogens. Well known for its potent pro-inflammatory and anti-viral functions in the periphery, the IFN-γ/STAT1 pathway is rapidly activated then deactivated to prevent excessive inflammation; however, neurons utilize unique IFN-γ/STAT1 activation patterns, which may contribute to the non-canonical neuron-specific downstream effects. Though it is now well-established that the immune system interacts and supports the CNS in health and disease, many aspects regarding IFN-γ production in the CNS and how neurons respond to IFN-γ are unclear. Additionally, it is not well understood how the diversity of the IFN-γ/STAT1 pathway is regulated in neurons to control homeostatic functions, support immune surveillance, and prevent pathologies. In this review, we discuss the neuron-specific mechanisms and kinetics of IFN-γ/STAT1 activation, the potential sources and entry sites of IFN-γ in the CNS, and the diverse set of homeostatic and pathological effects IFN-γ/STAT1 signaling in neurons has on CNS health and disease. We will also highlight the different contexts and conditions under which IFN-γ-induced STAT1 activation has been studied in neurons, and how various factors might contribute to the vast array of downstream effects observed.

Neuroprotective effects of 18ß-glycyrrhetinic acid against bisphenol A-induced neurotoxicity in rats: involvement of neuronal apoptosis, endoplasmic reticulum stress and JAK1/STAT1 signaling pathway.

The exposure to bisphenol A (BPA) is inevitable owing to its common use in the production of polycarbonate plastics. Studies to reduce side effects are gaining importance since BPA causes severe toxicities in important tissues such as testes, lungs, brain, liver and kidney. The current study was planned to study ameliorative effect of 18ß-glycyrrhetinic acid (18ß-GA) on BPA induced neurotoxicity. Fourty Wistar albino rats were divided into five equal groups as follows: I-Control group, II-18ß-GA group (100 mg/kg), III- BPA group (250 mg/kg), IV-250 mg/kg BPA + 50 mg/kg 18ß-GA group, V-250 mg/kg BPA + 100 mg/kg 18ß-GA group. BPA intoxication was associated with increased MDA level while reduced GSH concentration, activities of glutathione peroxidase, superoxide dismutase, and catalase. BPA supplementation caused apoptosis in the brain by up-regulating caspase-3 and Bax levels and down-regulating Bcl-2. BPA also caused endoplasmic reticulum (ER) stress by increasing mRNA transcript levels of PERK, IRE1, ATF-6 and GRP78. Additionally, it was observed that BPA administration activated JAK1/STAT1 signaling pathway and levels of TNF-α, NF-κB, p38 MAPK and JNK in the brain. However, co-treatment with 18ß-GA at a dose of 50 and 100 mg/kg considerably ameliorated oxidative stress, inflammation, apoptosis, ER stress and JAK1/STAT1 signaling pathway in brain tissue. Overall, the data of this study indicate that brain damage associated with BPA toxicity could be ameliorated by 18ß-GA administration.

Impact of heat stress on prolactin-mediated ovarian JAK-STAT signaling in postpubertal gilts.

Heat stress (HS) compromises almost every aspect of animal agriculture including reproduction. In pigs, this infecundity is referred to as seasonal infertility (SI), a phenotype including ovarian dysfunction. In multiple species, HS-induced hyperprolactinemia has been described; hence, our study objectives were to characterize and compare HS effects on circulating prolactin (PRL) and ovarian Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling during the follicular (FOL) or luteal (LUT) phases of the estrous cycle in postpubertal gilts. Gilts were estrus synchronized using altrenogest and environmental treatments began immediately after altrenogest withdrawal. For the FOL study: postpubertal gilts were allocated to constant thermoneutral (TN; n = 6; 20 ± 1.2 °C) or cyclical HS (n = 6; 25 to 32 ± 1.2 °C) conditions for 5 d. In the LUT study: postpubertal gilts were assigned to either TN (n = 7; 20 ± 2.6 °C) or cyclical HS (n = 7; 32 to 35 ± 2.6 °C) conditions from 2 to 12 days postestrus (dpe). Blood was collected by jugular venipuncture for PRL quantification on day 5 in the FOL and on day 0 and day 12 in the LUT gilts. Ovaries and corpora lutea (CL) were obtained from euthanized FOL and LUT gilts on day 5 and day 12, respectively. Western blotting was performed to quantify prolactin receptor (PRLR) and JAK/STAT pathway protein abundance. In the FOL phase, no difference (P = 0.20) in circulating PRL between thermal groups was observed. There was no effect (P ≥ 0.34) of HS on PRLR, signal transducer and activator of transcription 3 (STAT3), signal transducer and activator of transcription 5α (STAT5α), and phosphorylated signal transducer and activator of transcription α/ß tyrosine 694/699 (pSTAT5α/ßTyr694/699) abundance and Janus kinase 2 (JAK2), phosphorylated janus kinase 2 tyrosine 1007/1008 (pJAK2Tyr1007/1008), STAT1, phosphorylated signal transducer and activator of transcription 1 tyrosine 701 (pSTAT1Tyr701), phosphorylated signal transducer and activator of transcription 1 serine 727 (pSTAT1Ser727), and phosphorylated signal transducer and activator of transcription 3 tyrosine 705 (pSTAT3Tyr705) were undetectable in FOL gilt ovaries. Ovarian pSTAT5α/ßTyr694/699 abundance tended to moderately increase (4%; P = 0.07) in FOL gilts by HS. In the LUT phase, circulating PRL increased progressively from 2 to 12 dpe, but no thermal treatment-induced difference (P = 0.37) was noted. There was no effect (P ≥ 0.16) of HS on CL abundance of PRLR, pJAK2Tyr1007/1008, JAK2, STAT1, pSTAT1Tyr701, pSTAT1Ser727, pSTAT3Tyr705, STAT5α, or pSTAT5α/ßTyr694/699. In LUT phase, CL STAT3 abundance was increased (11%; P < 0.03) by HS. There was no impact of HS (P ≥ 0.76) on levels of pJAK2Tyr1007/1008 and pSTAT5α/ßTyr694/699 in LUT gilts; however, the CL pSTAT3Tyr705:STAT3 ratio tended to be decreased (P = 0.10) due to HS. These results indicate an HS-induced estrous cycle-stage-dependent effect on the ovarian JAK/STAT pathway, establishing a potential role for this signaling pathway as a potential contributor to SI.

Heat stress (HS) negatively affects reproduction in pigs, though the precise mechanisms are not understood. This study determined if HS impacts the JAK-STAT signaling pathway in the ovary during two stages of the estrous cycle: follicular and luteal. While circulating prolactin hormone level was unchanged, there were changes to some aspects of ovarian JAK-STAT signaling that could be involved in infertility induced in pigs during HS.

Topical Administration of 0.3% Tofacitinib Suppresses M1 Macrophage Polarization and Allograft Corneal Rejection by Blocking STAT1 Activation in the Rat Cornea.

Purpose: M1 macrophages can promote corneal allograft rejection (CGR). Inhibiting M1 macrophage polarization by the JAK/STAT1 pathway may be a new strategy to prevent CGR. Tofacitinib, a potent pan-JAK inhibitor, can inhibit JAK/STAT activation. Here, we investigated the inhibitory effects of tofacitinib on M1 macrophage polarization and its therapeutic effect on rat CGR. Methods: Corneal allograft transplantation was performed and administrated with 0.3% tofacitinib in rats. The corneal allografts were assessed clinically. The corneas were detected for M1 macrophages, lymphatic vessels, and inflammatory cytokine expression using immunohistochemistry and real-time polymerase chain reaction (PCR). Dendritic cells (DCs) in ipsilateral cervical lymph nodes were detected by flow cytometry. The effect and mechanism of tofacitinib on macrophages were explored by real-time PCR, enzyme-linked immunoassay, and western blot analysis in vitro. Results: The results showed that topical administration of 0.3% tofacitinib significantly prolonged corneal graft survival. Tofacitinib-treated corneal allografts displayed a proportionate decrease in M1 macrophages and reduced lymphatic vessel density with fewer DCs in rat ipsilateral cervical lymph nodes. Tofacitinib reduced the mRNA expression of inflammatory cytokines, including iNOS, MCP-1, TNF-α, IL-6, IL-1ß, and VEGF-C, and inhibited STAT1 activation in rat corneal grafts. In addition, tofacitinib suppressed M1 macrophage polarization via STAT1 activation after IFN-γ and lipopolysaccharide stimulation in vitro. Conclusions: Tofacitinib could suppress M1 macrophage polarization and subsequently delay CGR by inhibiting STAT1 activation. The data indicate that tofacitinib is an effective drug for CGR. Translational Relevance: This study provided evidence that topical administration of 0.3% tofacitinib may be a novel clinical strategy to prevent CGR.

Effects of Thymosin ß4 on Myocardial Apoptosis in Burned Rats.

The aim of this study was to investigate the effects of thymosin ß4 on myocardial apoptosis following burns. Fifty healthy Sprague Dawley (SD) rats were randomly divided into the normal control group, resuscitation group the low-dose Tß4 (thymosin ß4) group (2g), the medium-dose Tß4 group (6g), and the high-dose Tß4 group (18g). The rats were immersed in 95°C hot water for 18 seconds, and then the model of 30% body surface area (TBSA) III° scald was established. The resuscated rats were injected with lactate Ringer's solution for antishock rehydration, while the Tß4 treatment group was injected with lactate Ringer's solution for antishock rehydration, and the animals were sacrificed 6 h after scald. The degree of histopathological damage was observed by HE (hematoxylin and eosin) staining. Western blot was used to detect STAT1 and STAT3 protein expression levels. Real-time PCR was used to detect mRNA expressions of STAT1 and STAT3. The results showed that the apoptosis rate of the resuscitation group was significantly higher than that of the control group (P < 0.01). Compared with the resuscitation group, the apoptosis rate of thymosin ß4 in the treatment group was significantly reduced (P < 0.01). Compared with the normal control group, the expression of STAT1 protein was increased and the expression of STAT3 protein was decreased in model group rats after ischemia and reperfusion. Compared with the model group, the expression of STAT1 protein decreased and the expression of STAT3 protein increased after ischemia-reperfusion in the thymosin ß4 treatment group. Thymosin ß4 may protect the myocardium by downregulating STAT1 and upregulating STAT3 expression and inhibiting myocardial apoptosis induced by ischemia and reperfusion after severe scald injury.

Anti-TIM1 suppresses airway inflammation and hyperresponsiveness via the STAT6 /STAT1 pathways in mice with allergic asthma.

T cell immunoglobulin and mucin domain-1 (TIM-1) is a transmembrane glycoprotein and has been reported as an molecular mechanism of allergic diseases. This study aimed to explore the effects of anti-TIM-1 monoclonal antibodies (anti-TIM1) on the development of allergic asthma. Female C57BL/6 mice were induced and challenged with ovalbumin (OVA) and received subsequent intranasal administration of anti-TIM1. The airway resistance of all mice was evaluated using a Buxco PFT system. Flow cytometry was used to detect the expression of TIM-1 in peripheral blood mononuclear cells. The level of cytokine production in the bronchial alveolar lavage fluid and serum was determined using ELISA. Mucous cells were observed using Alcian blue and periodic acid-Schiff staining. In addition, B-cell lymphoma gene 2(BCL2), T-box transcription factor (T-bet), GATA binding protein-3(GATA3), signal transducer and activator of transcription (STAT) 1, STAT6 were analyzed by western blot analysis. Their corresponding mRNA expression levels were determined by quantitative PCR. The mRNA expression level of Mucin 5AC in the lung tissues was also detected using quantitative RT-PCR. The results showed that the intranasal administration of anti-TIM1 ameliorated airway inflammation and hyperresponsiveness in an acute model of asthma. Following administration of anti-TIM1, both the mRNA and protein levels of T-bet were upregulated, while those of BCL2 and GATA3 were downregulated. Moreover, the phosphorylation levels of STAT1 and STAT6 were increased. Taken together, these findings demonstrated that intranasal administration of anti-TIM1 ameliorated allergic lung inflammation and remodeling in mouse models of asthma by repairing both the STAT1 and STAT6 pathways.

The Effects of Mannuronic Acid on IL-1ß, IL-17A, STAT1, and STAT3 Gene Expressions and TLR2 and TLR4 Molecules in Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic neurologic disease defined by inflammation and demyelination of the central nervous system that comes with variable degrees of axonal and neuronal damage. The efficacy of ß-D-mannuronic acid (M2000) as a novel drug with immunosuppressive properties (patented: PCT/EP2017/067920), has been shown in an experimental model of MS. In this study, the effects of M2000 on interleukin (IL)-1ß, IL-17A, signal transducer and activator of transcription (STAT) 1, and STAT3 gene expressions and Toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) molecules in patients with secondary progressive MS were evaluated. In this study, 14 patients with secondary progressive MS and 14 healthy subjects (as control group) were entered from the phase 2 clinical trial (Clinical Trial identifier, IRCT2016111313739N6). The gene expressions of IL-1ß, IL-17A, STAT1, and STAT3 were assessed at the baseline and then measured after 6 months of therapy with M2000 by using the quantitative real-time polymerase chain reaction method. Moreover, the expressions of TLR2 and TLR4 molecules on peripheral blood mononuclear cells were evaluated by the flow cytometry method. The gene expressions of IL-17A, STAT1, and STAT3 in patients with MS decreased after 6 months of therapy with M2000 comparing before treatment. Also, the gene expression of IL-1ß decreased numerically after 6 months. Furthermore, the expressions of TLR2 and TLR4 on PBMCs of the patients declined when compared to baseline. The results of this investigation revealed that M2000 could downregulate IL-17, STAT1, and STAT3 genes in patients with secondary progressive MS and also reduce the expressions of TLR2 and TLR4 on PBMCs. Moreover, M2000 declined numerically IL-ß gene expression.

Coniferyl aldehyde alleviates LPS-induced WI-38 cell apoptosis and inflammation injury via JAK2-STAT1 pathway in acute pneumonia.

Pneumonia is a kind of inflammatory disease characterized by pathogen infection of lower respiratory track. Lipopolysaccharide (LPS) is the main bioactive component of Gram-negative bacteria responsible for inflammatory response. Recently, coniferyl aldehyde (CA) has been reported to play a crucial role because of its anti-inflammatory activity. However, the effect and mechanisms of CA in ameliorating symptoms of acute pneumonia remain unknown. Evaluating and identifying the value and exploring the mechanisms of CA on LPS-mediated WI-38 apoptosis and inflammation were the aims of this study. Here, CCK-8 cell viability assay was applied on WI-38 after treatment with or without LPS at different doses of CA to verify that CA can increase LPS-induced cell viability. Then, quantitative polymerase chain reaction (qPCR) and enzyme-linked-immunosorbent serologic assays (ELISA) suggested that LPS treatment dramatically decreased the expression level of IL-10 (anti-inflammatory factor) while strikingly increasing the expression levels of IL-1ß, IL-6, and TNF-α (tumor necrosis factor-α; proinflammatory factor) whereas CA treatment attenuates LPS-induced inflammation of WI-38. Further, flow cytometry and Western blot assay verified that LPS treatment dramatically promoted apoptosis of WI-38 cells, while administration of CA notably inhibited apoptosis of WI-38 cells. Moreover, the Western blot assay hinted that CA could inactivate LPS-induced JAK2-STAT1 signaling pathway. These findings indicated that CA could alleviate LPS-mediated WI-38 apoptosis and inflammation injury through JAK2-STAT1 pathway in acute pneumonia.

Janus kinase inhibitors for atopic dermatitis: a promising treatment modality.

Atopic dermatitis (AD) is chronic, pruritic, inflammatory skin disease that affects a significant portion of the population in industrialized nations. For nonresponders to conventional therapies, AD can significantly reduce sleep quality and quality of life. AD pathogenesis is multifactorial and involves multiple immune pathways, with recent evidence of T helper (Th)2, Th17 and Th22 axis attenuation in various AD endotypes and racial subtypes. Inhibition of the conserved Janus kinase (JAK) signalling pathway represents a promising therapeutic avenue to reduce the activation of multiple proinflammatory mediators involved in AD pathogenesis. JAK inhibitors exist in both oral and topical forms with variable specificity for the receptor tyrosine kinases JAK1, JAK2, JAK3 and tyrosine kinase 2. Oral formulations include abrocitinib, upadacitinib, baricitinib and gusacitinib, and are most appropriate for patients with moderate to severe AD. Emerging topical formulation in development include ruxolitinib and deglocitinib, which may be used in patients with localized AD and also adjunctively with systemic therapy in patients with more severe disease. With observed rapidity in itch relief and accompanying dramatic reduction in inflammatory lesion count, JAK inhibitors represent a promising new treatment to revolutionize the management of AD.

Statins downregulate K6a promoter activity: a possible therapeutic avenue for pachyonychia congenita.

Pachyonychia congenita (PC) is a keratinizing disorder predominantly caused by mutations in keratin 6a (K6a) (∼50% of cases) or K6b, K16, or K17. One means of treating PC is identification of small-molecule inhibitors of PC-related keratins. Here, we cloned the human K6a promoter, and using a cell-based reporter gene assay, a chemical library was screened for K6a inhibitors. One compound, compactin, the precursor of all cholesterol-lowering statins, was of particular interest. We found that, surprisingly, simvastatin and other statins inhibit K6a promoter activity and K6a protein expression. Further investigation showed that this effect works through cholesterol/mevalonate pathway inhibition rather than an off-target effect. Inhibition of both basal and IFN-γ-inducible K6a expression by statins was demonstrated. Both these K6a inhibitory effects were found to be mediated by Stat1 transcription factor, but only the IFN-γ-inducible promoter activity was controlled via the Stat/JAK pathway. The repressive effect of statins was found to be mediated by the isoprenoid pathway downstream of mevalonate (the intermediate following 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase) but upstream of cholesterol, specifically the geranylgeranylation pathway. These data set the scene for further unraveling signaling pathways that control the K6a promoter, as well as facilitating clinical trials for statins in PC patients.

Activation of signal transducer and activator of transcription factor 1 by interleukins-13 and -4 in cultured human bronchial smooth muscle cells.

The family of signal transducer and activator of transcription (STAT) factors play a critical role in the signaling of many cytokines. In addition to the involvement of STAT6 in allergic bronchial asthma, both STAT1 and STAT3 have also been implicated. However, there is little information whether or not the T helper 2 cytokines, which cause several key features of allergic asthma, really induce the activation of STAT1 and/or STAT3 in bronchial smooth muscle (BSM) cells. In the present study, the effects of interleukin-13 (IL-13) and IL-4 on activation of these STAT molecules were examined in cultured human bronchial smooth muscle cells (hBSMCs). After a starvation period, the hBSMCs were treated with 100 ng/ml of IL-13 or IL-4. Total protein samples were prepared at intervals of 1, 3, 6, 12 and 24 hours after the cytokine treatment, and Western blot analyses for total and tyrosine-phosphorylated STATs molecules were conducted. As a result, ut was found that both IL-13 and IL-4 caused a significant increase in the levels of phosphorylated STAT1. Examination of the time-course revealed a peak of STAT1 phosphorylation at 1 hr after cytokine application. In contrast, neither IL-13 nor IL-4 induced phosphorylation of STAT3. Neither of these cytokines changed the protein expression of the STATs themselves. These findings suggest that STAT1, but not STAT3, might also be one of the crucial signal transducers in the development of BSM hyper-responsiveness, which is one of the causes of AHR in asthmatics.