High mobility group box 1 contributes to wound healing induced by inhibition of dipeptidylpeptidase 4 in cultured keratinocytes

The Role of Sirtuins in the Pathogenesis of Psoriasis

Psoriasis is the most common chronic inflammatory skin disease with a genetic basis. It is characterised by keratinocyte hyperproliferation, parakeratosis and inflammatory cell infiltration. Psoriasis negatively affects a patient's physical and emotional quality of life. Sirtuins (SIRTs; silent information regulators) are an evolutionarily conserved group of enzymes involved in the post-translational modification of proteins, including deacetylation, polyADP-ribosylation, demalonylation and lipoamidation. SIRTs are involved in a number of cellular pathways related to ageing, inflammation, oxidative stress, epigenetics, tumorigenesis, the cell cycle, DNA repair and cell proliferation, positioning them as an essential component in the pathogenesis of many diseases, including psoriasis. Activation of SIRT1 counteracts oxidative-stress-induced damage by inhibiting the mitogen-activated protein kinases (MAPK), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription 3 (STAT3) pathways and may mitigate pathological events in psoriasis. There is a significant reduction in the expression of SIRT1, SIRT2, SIRT3, SIRT4 and SIRT5 and an increase in the expression of SIRT6 and SIRT7 in psoriasis. The aim of the review is to draw the attention of physicians and scientists to the importance of SIRTs in dermatology and to provide a basis and impetus for future discussions, research and pharmacological discoveries to modulate SIRT activity. In light of the analysis of the mode of action of SIRTs in psoriasis, SIRT1-SIRT5 agonists and SIRT6 and SIRT7 inhibitors may represent new therapeutic options for the treatment of psoriasis.

Subcellular Epithelial HMGB1 Expression Is Associated with Colorectal Neoplastic Progression, Male Sex, Mismatch Repair Protein Expression, Lymph Node Positivity, and an 'Immune Cold' Phenotype Associated with Poor Survival

New treatment targets are needed for colorectal cancer (CRC). We define expression of High Mobility Group Box 1 (HMGB1) protein throughout colorectal neoplastic progression and examine the biological consequences of aberrant expression. HMGB1 is a ubiquitously expressed nuclear protein that shuttles to the cytoplasm under cellular stress. HMGB1 impacts cellular responses, acting as a cytokine when secreted. A total of 846 human tissue samples were retrieved; 6242 immunohistochemically stained sections were reviewed. Subcellular epithelial HMGB1 expression was assessed in a CRC Tissue Microarray (n = 650), normal colonic epithelium (n = 75), adenomatous polyps (n = 52), and CRC polyps (CaP, n = 69). Stromal lymphocyte phenotype was assessed in the CRC microarray and a subgroup of CaP. Normal colonic epithelium has strong nuclear and absent cytoplasmic HMGB1. With progression to CRC, there is an emergence of strong cytoplasmic HMGB1 (p < 0.001), pronounced at the leading cancer edge within CaP (p < 0.001), and reduction in nuclear HMGB1 (p < 0.001). In CRC, absent nuclear HMGB1 is associated with mismatch repair proteins (p = 0.001). Stronger cytoplasmic HMGB1 is associated with lymph node positivity (p < 0.001) and male sex (p = 0.009). Stronger nuclear (p = 0.011) and cytoplasmic (p = 0.002) HMGB1 is associated with greater CD4⁺ T-cell density, stronger nuclear HMGB1 is associated with greater FOXP3⁺ (p < 0.001) and ICOS⁺ (p = 0.018) lymphocyte density, and stronger nuclear HMGB1 is associated with reduced CD8⁺ T-cell density (p = 0.022). HMGB1 does not directly impact survival but is associated with an 'immune cold' tumour microenvironment which is associated with poor survival (p < 0.001). HMGB1 may represent a new treatment target for CRC.

Dipeptidyl Peptidase-4 Inhibitor-Related Bullous Pemphigoid: Clinical, Laboratory, and Histological Features, and Possible Pathogenesis

Dipeptidyl peptidase-4 inhibitor (DPP4i) is a widely used antidiabetic agent. Emerging cases of DPP4i-associated bullous pemphigoid (DBP), whose pathogenesis remains unclear, have been reported. Thus, a retrospective study was conducted from January 2016 to June 2021 to determine the clinical, laboratory, and histopathological features of DBP and idiopathic bullous pemphigoid (IBP). We set up in vitro experiments using vildagliptin-treated HaCaT keratinocytes to validate what we found by analyzing published RNA sequencing data about the genes related to the dermal-epidermal junction. We also observed IL-6 expression by HaCaT cells treated with vildagliptin. We enrolled 20 patients with DBP and 40 patients with IBP. The total Bullous Pemphigoid Disease Area Index (BPDAI) score was similar in both groups. However, the BPDAI score of erosions and blisters in DBP was significantly higher than that in IBP (24.6 vs. 16.68, p = 0.0189), and the score for urticaria and erythema was lower in DBP (12 vs. 19.05, p = 0.0183). The pathological features showed that the mean infiltrating eosinophil number per high-power field was significantly lower in DBP than in IBP (16.7 vs. 27.08, p = 0.023). The expression of LAMA3, LAMB3, LAMC2, DST, and COL17A1 decreased significantly in vildagliptin-treated human keratinocytes. On the other hand, IL-6, the hallmark cytokine of bullous pemphigoid (BP) severity, was found to be upregulated in HaCaT cells by vildagliptin. These experimental findings imply less of a requirement for eosinophil infiltration to drive the inflammatory cascades in DBP blistering. Both immunologic and non-immunologic pathways could be employed for the development of DBP. Our findings may help explain the higher incidence of non-inflammatory BP that was observed in DBP.

Microglia Contributes to BAF-312 Effects on Blood–Brain Barrier Stability

Microglia, together with astrocytes and pericytes, cooperate to ensure blood–brain barrier (BBB) stability, modulating endothelial responses to inflammatory insults. Agonists of the sphingosine 1 phosphate (S1P) receptors, such as siponimod (BAF-312), are important pharmacological tools in multiple sclerosis and other inflammatory diseases. Modulation of S1P receptors may result in a reduced inflammatory response and increased BBB stability. An in vitro BBB model was reproduced using human-derived endothelial cells, astrocytes and microglia. Co-cultures were exposed to inflammatory cytokines (TNFα, 10 UI and IFNγ, 5 UI) in the presence of BAF-312 (100 nM), and the BBB properties and microglia role were evaluated. The drug facilitated microglial migration towards endothelial/astrocyte co-cultures, involving the activity of the metalloprotease 2 (MMP2). Microglia actively cooperated with astrocytes in the maintenance of endothelial barrier stability: in the triple co-culture, selective treatment of microglial cells with BAF-312 significantly prevented cytokines’ effects on the endothelial barrier. In conclusion, BAF-312, modulating S1P receptors in microglia, may contribute to the reinforcement of the endothelial barrier at the BBB, suggesting an additional effect of the drug in the treatment of multiple sclerosis.

Cratoxylumxanthone C, a natural xanthone, inhibits lung cancer proliferation and metastasis by regulating STAT3 and FAK signal pathways

To discover phytochemicals as lead compounds for cancer treatment, cratoxylumxanthone C, a natural xanthone, was obtained from Cratoxylum cochinchinense (Lour.) Bl., for which there have been no reports on the biological effects against cancer. Our study revealed that cratoxylumxanthone C had significant anti-tumor activity by inducing apoptosis, augmenting cellular reactive oxygen species (ROS), and arresting cell circle. The mechanistic examination showed the inhibition of A549 cell proliferation and metastasis by cratoxylumxanthone C was coupled with the signal transducer and activator of transcription 3 (STAT3) and focal adhesion kinase (FAK) signaling pathways. Furthermore, the zebrafish models confirmed its significant in vivo anti-tumor activity, in which cratoxylumxanthone C inhibited tumor proliferation and metastasis and suppressed the angiogenesis. Comprehensively, these cellular and zebrafish experiments implied that cratoxylumxanthone C may have the potential to become an anti-tumor agent for lung cancer, especially non-small cell lung cancer (NSCLC).

Inverse correlation between the expression of AMPK/SIRT1 and NAMPT in psoriatic skin: A pilot study

PURPOSE

Epidermal hyperplasia and the involvement of immune cells characterize the clinical picture of psoriasis. Among the several factors involved, attention has been focused on sirtuin 1 (SIRT1) - a deacetylase endowed with a variety of functions including the control of metabolic and inflammatory processes-, and on nicotinamide phosphoribosyltransferase (NAMPT), important for SIRT1 activation and involved in inflammatory events. The aim of the study was to analyze changes of SIRT1 and NAMPT expression in psoriatic skin.

PATIENTS AND METHODS

Samples from healthy controls and psoriatic patients were subjected to immunohistochemical analysis.

RESULTS

A strong downregulation of SIRT1 expression was observed in skin samples from psoriatic patients compared to healthy controls. This was accompanied by a parallel reduction of adenosine monophosphate-activated kinase (AMPK) expression and, more strikingly, by the disappearance of cells immunolabeled for its active, phosphorylated form (pAMPK). In both cases, analysis of the distribution of immunopositive cells revealed a shift towards reduced intensity of staining. In contrast, NAMPT expression was upregulated in psoriatic samples in line with its pro-inflammatory role. This was again more visible with an intensity-based distribution analysis that evidenced a shift towards more intensely immunostained cell populations.

CONCLUSIONS

The present data correlate in the same samples the expression of SIRT1, pAMPK/AMPK and NAMPT in psoriasis and open the way for novel pharmacological targets in the treatment of the disease.

Influence of Dipeptidyl Peptidase-4 (DPP4) on Mesenchymal Stem-Cell (MSC) Biology: Implications for Regenerative Medicine - Review

Dipeptidyl peptidase IV (DPP4) is a ubiquitous protease that can be found in membrane-anchored or soluble form. Incretins are one of the main DPP4 substrates. These hormones regulate glucose levels, by stimulating insulin secretion and decreasing glucagon production. Because DPP4 levels are high in diabetes, DPP4 inhibitor (DPP4i) drugs derived from gliptin are widespread used as hypoglycemic agents for its treatment. However, as DPP4 recognizes other substrates such as chemokines, growth factors and neuropeptides, pleiotropic effects have been observed in patients treated with DPP4i. Several of these substrates are part of the stem-cell niche. Thus, they may affect different physiological aspects of mesenchymal stem-cells (MSC). They include viability, differentiation, mobilization and immune response. MSC are involved in tissue homeostasis and regeneration under both physiological and pathological conditions. Therefore, such cells and their secretomes have a high clinical potential in regenerative medicine. In this context, DPP4 activity may modulate different aspects of MSC regenerative capacity. Therefore, the aim of this review is to analyze the effect of different DPP4 substrates on MSC. Likewise, how the regulation of DPP4 activity by DPP4i can be applied in regenerative medicine. That includes treatment of cardiovascular and bone pathologies, cutaneous ulcers, organ transplantation and pancreatic beta-cell regeneration, among others. Thus, DPP4i has an important clinical potential as a complement to therapeutic strategies in regenerative medicine. They involve enhancing the differentiation, immunomodulation and mobilization capacity of MSC for regenerative purposes.

The role of Dipeptidyl Peptidase-4 in cutaneous disease

Dipeptidyl peptidase-4 (DPP4) is a multifunctional, transmembrane glycoprotein present on the cell surface of various tissues. It is present in multiple molecular forms including cell surface and soluble. The role of DPP4 and its inhibition in cutaneous dermatoses have been a recent point of investigation. DPP4 exerts a notable influence on T-cell biology, the induction of skin-specific lymphocytes, and the homeostasis between regulatory and effector T cells. Moreover, DPP4 interacts with a broad range of molecules, including adenosine deaminase, caveolin-1, CXCR4 receptor, M6P/insulin-like growth factor II-receptor and fibroblast activation protein-α, triggering downstream effects that modulate the immune response, cell adhesion and chemokine activity. DPP4 expression on melanocytes, keratinocytes and fibroblasts further alters cell function and, thus, has crucial implications in cutaneous pathology. As a result, DPP4 plays a significant role in bullous pemphigoid, T helper type 1-like reactions, cutaneous lymphoma, melanoma, wound healing and fibrotic disorders. This review illustrates the multifactorial role of DPP4 expression, regulation, and inhibition in cutaneous diseases.

Advanced Glycation End Products and Receptor (RAGE) Promote Wound Healing of Human Corneal Epithelial Cells

Purpose

We used a human corneal epithelial cell (HCE) line to determine the involvement of the advanced glycation end products (AGEs) / receptor for AGEs (RAGE) couple in corneal epithelium wound healing.

Methods

After wounding, HCE cells were exposed to two major RAGE ligands (HMGB1 and AGEs), and wound healing was evaluated using the in vitro scratch assay. Following wound healing, the HCE cells were used to study the influence of the RAGE ligands on HCE proliferation, invasion, and migration. Activation of the nuclear factor (NF)-κB signaling pathway by the AGEs/RAGE couple was tested using a luciferase reporter assay. Functional transcriptional regulation by this pathway was confirmed by quantification of expression of the connexin 43 target gene. For each experiment, specific RAGE involvement was confirmed by small interfering RNA treatments.

Results

AGEs treatment at a dose of 100 µg/mL significantly improved the wound healing process in a RAGE-dependent manner by promoting cell migration, whereas HMGB1 had no effect. No significant influence of the AGEs/RAGE couple was observed on cell proliferation and invasion. However, this treatment induced an early activation of the NF-κB pathway and positively regulated the expression of the target gene, connexin 43, at both the mRNA and protein levels.

Conclusions

Our results demonstrate that the RAGE pathway is activated by AGEs treatment and is involved in the promotion of corneal epithelial wound healing. This positive action is observed only during the early stages of wound healing, as illustrated by the quick activation of the NF-κB pathway and induction of connexin 43 expression.

The Treatment of Impaired Wound Healing in Diabetes: Looking among Old Drugs

Chronic wounds often occur in patients with diabetes mellitus due to the impairment of wound healing. This has negative consequences for both the patient and the medical system and considering the growing prevalence of diabetes, it will be a significant medical, social, and economic burden in the near future. Hence, the need for therapeutic alternatives to the current available treatments that, although various, do not guarantee a rapid and definite reparative process, appears necessary. We here analyzed current treatments for wound healing, but mainly focused the attention on few classes of drugs that are already in the market with different indications, but that have shown in preclinical and few clinical trials the potentiality to be used in the treatment of impaired wound healing. In particular, repurposing of the antiglycemic agents dipeptidylpeptidase 4 (DPP4) inhibitors and metformin, but also, statins and phenyotin have been analyzed. All show encouraging results in the treatment of chronic wounds, but additional, well designed studies are needed to allow these drugs access to the clinics in the therapy of impaired wound healing.

Restoration of calcium-induced differentiation potential and tight junction formation in HaCaT keratinocytes by functional attenuation of overexpressed high mobility group box-1 protein

HaCaT cells have been widely used as undifferentiated epidermal keratinocytes, since these non-tumorigenic cells can be readily maintained in conventional medium and partly retain epidermal differentiation potential upon stimulation with high concentration of calcium. In contrast to primary epidermal keratinocytes, however, these cells never form tight junction (TJ), a specific structure in highly differentiated keratinocytes, solely by the differentiation stimulation. Here, we show that HaCaT cells secrete a considerable amount of high mobility group box-1 protein (HMGB1), one of major inflammatory mediator, which appeared to be responsible, at least in part, for such aberrant differentiation response. So far, inhibition of c-Jun N-terminal kinase (JNK) in high calcium medium has been supposed to be the only way to induce TJ formations in HaCaT cells; however, SP600125, a potent inhibitor of JNK showed cytostatic effects and clearly attenuated epidermal differentiation and stratification. In contrast, dipotassium glycyrrhizate (GK2), a soluble analogue of HMGB1-blocker Glycyrrhizin, down-regulated interferon-β, a typical inflammatory cytokine induced by secreted HMGB1, and accelerated differentiation responses to the calcium treatment in these cells. In addition, GK2-treatmenrt resulted in the formation of double cell layers in cultured HaCaT cells, where the stratified upper cells transiently accumulated TJ proteins at the cell-cell contact sites. These results highlight the importance of attenuation of secreted HMGB1-signals in cultured HaCaT cells for studies of functional keratinocytes.

The Ambiguous Role of Microglia in Aβ Toxicity: Chances for Therapeutic Intervention

Amyloid-β (Aβ) has long been shown to be critical in Alzheimer's disease pathophysiology. Microglia contributes to the earliest responses to Aβ buildup, by direct interaction through multiple receptors. Microglial cells operate Aβ clearance and trigger inflammatory/regenerative processes that take place in the long years of silent disease progression that precede symptomatic appearance. But in time and with aging, the fine balance between pro- and anti-inflammatory activity of microglia deranges, negatively impacting its Aβ-clearing ability. Furthermore, in recent years, microglial activation has proven to be much more complex than the mere dichotomic pro/antiinflammatory polarization previously accepted. Microglia can display a wide spectrum of phenotypes, which can even be mixed. On these bases, it is evident that while pharmacological intervention aiding microglia to prolong its ability to cope with Aβ buildup could be extremely relevant, its feasibility is hampered by such high complexity, which still needs to be completely understood.

Increased risk of bullous pemphigoid in dipeptidyl peptidase 4 inhibitors: A nationwide, population-based, cohort study in Taiwan

Recent studies revealed the risk of bullous pemphigoid (BP) in patients with diabetes mellitus (DM) taking dipeptidyl peptidase 4 (DPP-4) inhibitors. To clarify the relationship between taking DPP-4 inhibitors and the risk of BP among patients with DM, we conducted a cohort study by using the National Health Insurance Research Database of Taiwan from 1 January 2009 to 31 December 2015. We identified 6340 patients with DM taking DPP-4 inhibitors and 25 360 DM patients who had not taken DPP-4 inhibitors during the 7-year follow-up period. Compared with the non-DPP-4 inhibitor group, patients taking DDP-4 inhibitors had a higher risk of BP (adjusted hazard ratio [aHR], 2.382; 95% confidence interval (CI), 1.163-4.883; P = 0.017]. Among the DPP-4 inhibitors available in Taiwan, vildagliptin showed the highest risk of BP (aHR, 2.849; 95% CI, 1.893-4.215; P < 0.001), followed by saxagliptin (aHR, 2.657; 95% CI, 1.770-3.934; P < 0.001). Subgroup analysis revealed that the higher risk of BP was observed in patients older than 65 years (aHR, 2.403; 95% CI, 1.590-3.627; P < 0.001). This study revealed that treatment with DPP-4 inhibitors, especially vildagliptin, was significantly associated with an increased risk of BP among DM patients.

Incretin-based therapy for diabetic ulcers: from bench to bedside

INTRODUCTION

Diabetic foot ulcers are a serious complication of diabetes and are associated with pain, disability, and poor quality of life. Incretin-based therapy is available for type-2 diabetes. Aside from glucose control, such treatment can impart numerous beneficial effects.

AREAS COVERED

This review summarizes the preclinical and clinical evidence supporting incretin-based treatment approaches for diabetic ulcers.

EXPERT OPINION

Incretin-based therapy may have a role in the treatment of diabetic foot ulcers; the benefits of such treatment arise from attenuation of inflammatory response, improvement of keratinocyte migration, induction of angiogenesis, and the enhancement of tissue remodeling. Large-scale clinical trials are required to determine the advantages of GLP-1 receptor agonists and DPP4 inhibitors. Future research on the topical application of incretin-based therapy is necessary. Such therapeutic approaches may provide new hope in improving the treatment of impaired diabetic foot ulcers.

Quantitative Top-Down Mass Spectrometry Identifies Proteoforms Differentially Released during Mechanical Stimulation of Mouse Skin

Mechanotransduction refers to the processes whereby mechanical stimuli are converted into electrochemical signals that allow for the sensation of our surrounding environment through touch. Despite its fundamental role in our daily lives, the molecular and cellular mechanisms of mechanotransduction are not yet well-defined. Previous data suggest that keratinocytes may release factors that activate or modulate cutaneous sensory neuron terminals, including small molecules, lipids, peptides, proteins, and oligosaccharides. This study presents a first step toward identifying soluble mediators of keratinocyte-sensory neuron communication by evaluating the potential for top-down mass spectrometry to identify proteoforms released during 1 min of mechanical stimulation of mouse skin from naı̈ve animals. Overall, this study identified 47 proteoforms in the secretome of mouse hind paw skin, of which 14 were differentially released during mechanical stimulation, and includes proteins with known and previously unknown relevance to mechanotransduction. Finally, this study outlines a bioinformatic workflow that merges output from two complementary analysis platforms for top-down data and demonstrates the utility of this workflow for integrating quantitative and qualitative data.

Alerting the body to tissue injury: The role of alarmins and DAMPs in cutaneous wound healing

Purpose of review

Tissue injury stimulates an inflammatory response that is mediated in part by alarmins. Alarmins are a group of endogenous molecules that trigger inflammation in response to damage. This class of molecules is becoming increasingly recognized for their ability to influence wound healing. This article will provide an overview of alarmins and outline the latest findings on these mediators in cutaneous wound healing.

Recent findings

In addition to stimulating inflammatory cells, recent evidence suggests that alarmins can act on other cells in the skin to affect wound closure and the extent of scar tissue production. This review will focus on HMGB-1 and IL-33, two alarmins that have received recent attention in the wound healing field.

Summary

Because a properly regulated inflammatory response is critical for optimal healing, further research must be done to fully understand the role of alarmins in the wound repair process.

VEGF stimulated the angiogenesis by promoting the mitochondrial functions

The vascular endothelial growth factor (VEGF) signaling pathway involved in angiogenesis which plays a pivotal role in normal development and also represents a major therapeutic target for tumors and intraocular neovascular disorders. The aims of the present study were to evaluate the effects of VEGF on endothelial cells and clarify the mechanism. Here, we showed that VEGF significantly stimulated the proliferation, migration and cell cycle of endothelial cells, and it also induced tube formation in vitro significantly. What's more, the mitochondrial functions were enhanced in response to VEGF, including mitochondrial oxidative respiration and intracellular ATP levels. The reactive oxygen species (ROS) production decreased, while the enzymes of ROS defence system, including catalase and glutathione peroxidase (GPX1), whose expression both increased in the VEGF stimulation. VEGF activated mammalian target of rapamycinm (mTOR) signaling pathway to promote the function of mitochondria. Rapamycin, the inhibitor of mTOR pathway could inhibit the proliferation and cell cycle induced by VEGF. In summary, our study identified that VEGF promoted the angiogenesis and provided evidence for mitochondria as new therapeutic target of VEGF signaling in the angiogenic vascular disorders.

Dipeptidyl Peptidase-4, Wound Healing, Scarring, and Fibrosis

Scarring and fibrosis are an enormous public health concern, resulting in excessive morbidity and mortality in addition to countless lost health care dollars. Recent advances in cell and developmental biology promise a better understanding of scarring and fibrosis and may translate to new clinical therapies.

Involvement of DPP IV/CD26 in cutaneous wound healing process in mice

Dipeptidyl peptidase IV (DPP IV/CD26) is a widely distributed multifunctional protein that plays a significant role in different physiological as well as pathological processes having a broad spectrum of bioactive substrates and immunomodulative properties. It has potential influence on different processes crucial for wound healing, including cell adhesion, migration, apoptosis, and extracellular matrix degradation. However, despite its known enzymatic and immunomodulative functions, limited data characterize the role of DPP IV/CD26 in cutaneous wound healing mechanisms. The aim of this study was to investigate the process of wound healing in conditions of CD26 deficiency in order to obtain better insights on the role of DPP IV/CD26 in cutaneous regeneration. Experimental wounds were made on the dorsal part of CD26 deficient (CD26^-/- ) and wild-type mice (C57BL/6). The process of cutaneous wound healing was monitored on defined time schedule postwounding by macroscopic, microscopic, and biochemical analyses. Obtained results revealed a better rate of wound closure, revascularization and cell proliferation in CD26^-/- mice, with enhanced local expression of hypoxia-inducible factor 1α and vascular endothelial growth factor. CD26 deficiency induced prompt macrophage recruitment at the site of skin damage but did not influence mobilization of T-cells in comparison with wild-type mice. CD26^-/- mice have significantly higher values of IP-10 in serum and control skins compared with wild-type mice but values in wounds did not differ significantly on days 2, 4, and 7 of wound healing. DPP IV/CD26 activity was found to be decreased 4 days postwounding in serum and 2, 4, and 7 days postwounding in wounds of wild-type animals compared with control skins. These findings contribute to better understanding of wound healing mechanisms and could give a support in finding new therapeutic approaches for wound healing and tissue regeneration.

Proinflammatory effect of high-mobility group protein B1 on keratinocytes: an autocrine mechanism underlying psoriasis development

Psoriasis is an autoimmune skin disease, in which keratinocytes play a crucial pathogenic role. High-mobility group protein B1 (HMGB1) is an inflammatory factor that can be released from keratinocyte nuclei in psoriatic lesions. We aimed to investigate the proinflammatory effect of HMGB1 on keratinocytes and the contribution of HMGB1 to psoriasis development. Normal human keratinocytes were treated with recombinant human HMGB1, and the production of inflammatory factors and the intermediary signalling pathways were examined. Furthermore, the imiquimod-induced psoriasis-like mouse model was used to investigate the role of HMGB1 in psoriasis development in vivo. A total of 11 inflammatory factors were shown to be upregulated by HMGB1 in keratinocytes, among which interleukin (IL)-18 showed the greatest change. We then found that activation of the nuclear factor-κB signalling pathway and inflammasomes accounted for HMGB1-induced IL-18 expression and secretion. Moreover, HMGB1 and downstream IL-18 contributed to the development of psoriasiform dermatitis in the imiquimod-treated mice. In addition, T-helper 17 immune response in the psoriasis-like mouse model could be inhibited by both HMGB1 and IL-18 blockade. Our findings indicate that HMGB1 secreted from keratinocytes can facilitate the production and secretion of inflammatory factors such as IL-18 in keratinocytes in an autocrine way, thus promoting the development of psoriasis. Blocking the proinflammatory function of the HMGB1-IL-18 axis may be useful for psoriasis treatment in the future. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Diurnal Variation of the Peripheral Cholinergic Antiinflammatory Function in Mice

AIMS

Cholinergic antiinflammatory (CAI) pathway functions importantly in inflammation via α7 nicotinic acetylcholine receptors (α7nAChR). The present work tested circadian rhythm in peripheral CAI activity and validities of CAI activity and glucocorticoids in chronotherapy for lipopolysaccharide (LPS)-induced shock.

METHODS

Vesicular acetylcholine transporter (VAChT) expressed in liver and kidney was examined every 3 h in C57BL/6 mice. Proinflammatory cytokines in serum and survival time in shock were monitored after LPS injection every 3 h. Mifepristone, antagonist of glucocorticoid receptors, and methyllycaconitine (MLA), antagonist of α7nAChR, were administrated before LPS to block antiinflammatory function of endogenous glucocorticoids and acetylcholine.

RESULTS

Both levels of tumor necrosis factor α, interleukin 1β, and interleukin 6 and mortality exhibited diurnal variations with prominent peaks when LPS was given at 15:00, and the minimum mortality occurred at 00:00. Expression of VAChT increased during resting period. MLA increased serum proinflammatory cytokines slightly, but not affected survival rate. Both differences in cytokines and in survival times between LPS injection at 15:00 and 00:00 were eliminated by mifepristone, but not by MLA.

CONCLUSION

Peripheral CAI pathway exerts more powerful antiinflammatory effect during resting period. Glucocorticoids appear to be efficient in chronotherapy for septic shock.

Sodium Sulfide, a Hydrogen Sulfide-Releasing Molecule, Attenuates Acute Cerebral Ischemia in Rats

AIMS

Acute cerebral ischemia may lead to ischemic stroke, which is a major cause of death and disability worldwide. Hydrogen sulfide (H2 S) functions importantly in mammalian systems. The present work was designed to study the effect of sodium sulfide, a donor of H2 S, on acute cerebral ischemia.

METHODS

Acute cerebral focal ischemia was produced by middle cerebral artery occlusion (MCAO) in Sprague-Dawley (SD) rats. Bilateral vertebral arteries and common carotid arteries were blocked to establish cerebral global ischemia in SD rats. Acute cerebral anoxia was produced by hypobaric anoxia in C57BL/6 mice and hypoxic anoxia in SD rats. Nimodipine and aspirin were set as positive control separately.

RESULTS

Infarct size after MCAO was decreased by sodium sulfide. Sodium sulfide improved cerebral energy metabolism after cerebral global ischemia and prolonged survival time of animals with acute cerebral anoxia. In addition, increased cerebral blood flow and decreased cerebrovascular resistance, blood viscosity, and thrombogenesis were observed in animals treated with sodium sulfide. In cultured neurons, sodium sulfide increased cell viability and decreased cell apoptosis induced by oxygen-glucose deprivation.

CONCLUSION

Sodium sulfide, a H2 S donor, presents protective effect on acute cerebral ischemia, and might be a promising therapeutic drug.

MiR-153 regulates metastases of gastric cancer through Snail

MicroRNAs (miRNAs) play critical roles in tumorigenesis and cancer metastases of gastric carcinoma (GC). Recently, miR-153 was reported as a tumor suppressor miRNA silenced in GC, whereas the underlying mechanisms are much lacking. Here, we reported that miR-153 levels were significantly decreased and Snail levels were significantly increased in GC specimens, compared to paired adjacent non-tumor gastric tissue. Moreover, the levels of miR-153 and Snail were inversely correlated. Bioinformatics analyses and luciferase reporter assay showed that miR-153 targeted the 3'-untranslated region (3'-UTR) of Snail messenger RNA (mRNA) to inhibit its translation. Overexpression of miR-153 inhibited Snail-mediated cell invasiveness, while depletion of miR-153 increased Snail-mediated cell invasiveness in both Transwell cell migration assay and scratch wound healing assay. Thus, our data suggest that miR-153 suppression in GC promotes Snail-mediated cancer metastases. Re-establishment of miR-153 levels in GC may suppress cancer invasion.