18β-glycyrrhetic acid inhibits immune activation triggered by HMGB1, a pro-inflammatory protein found in the tear fluid during conjunctivitis and blepharitis

Tear levels of apoptotic, matrix-degrading and antioxidant biomarkers in patients with and without keratoconus: A cross sectional study

PURPOSE

To assess the tear levels of a set of apoptotic, matrix-degrading and antioxidant biomarkers, including Metalloproteinase 9 (MMP9), High Mobility Group Box 1 (HMGB1) and Superoxide Dismutase 3-Extracellular (SOD3).

METHODS

Sandwich-ELISA commercial kits were used to test the expression of the three tear biomarkers in the lacrimal fluid of eligible participants. Linear logistic regression analysis was performed todetermine whether the set of tear biomarkers could be associated with clinically manifest keratoconus. ROC curve analysis using 10-fold cross-validation was performedto evaluate the prediction accuracy of the model.

RESULTS

Eighty-one participants aged 30-48 years old were enrolled in this study; 48 were patients with keratoconus and 33 were age-matched healthy subjects. The linear combination of the three tear biomarkers levels (AUC = 0.811; CI 95 %: 0.712-0.911) accurately indicated the existence of keratoconus; higher levels of MMP9 (Odd Ratio: 1.069; CI 95 %: 1.029-1.130) and HMGB1 (OR: 1.011; CI 95 %: 1.003-1.022) and lower levels of SOD3 (OR: 0.994; CI 95 %: 0.989-0.997) were significantly associated with a higher probability of keratoconus.

CONCLUSION

Multivariable analysis of the set of tear levels of MMP9, HMGB1 and SOD3 biomarkers confirmed a chronic state of inflammation in the ocular surface of patients with keratoconus.

In vitro validation: GLY alleviates UV-induced corneal epithelial damage through the HMGB1-TLR/MyD88-NF-κB signaling pathway

UV-induced corneal damage is a common ocular surface injury that usually leads to corneal lesions causing persistent inflammation. High mobility group box 1 (HMGB1) is identified as an inflammatory alarm in various tissue injuries. Here, this study first evaluates the repair effect of the HMGB1-selective inhibitor GLY in UV-induced corneal damage; Secondly, the inhibitory effect of GLY on UV-induced corneal damage induced inflammation and the potential therapeutic mechanism of GLY were studied. GLY effectively attenuates the expression of UV-induced inflammatory factors and HMGB1, TLR/MyD88, NF-κB signaling pathway genes at the mRNA and protein levels. In addition, RT-PCR and Western Blot experiments after knocking down HMGB1 and TLR2/9 genes showed that GLY alleviated corneal inflammation by inhibiting the HMGB1-TLR/MyD88 signaling pathway. The results of this study show that targeting HMGB1-NF-κB by GLY can alleviate the inflammatory response induced by UV induction.

Enhancing regulatory T-cell function via inhibition of high mobility group box 1 protein signaling in immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is the most common acquired autoimmune bleeding disorder. Abnormally increased levels of High Mobility Group Box 1 (HMGB1) protein associate with thrombocytopenia and therapeutic outcome in ITP. Previous studies proposed that a natural inhibitor of HMGB1, 18β-glycyrrhetinic acid (18β-GA), could be used for its anti-inflammatory and immune-modulatory effects, although its ability to correct immune balance in ITP is unclear. In this study, we showed that plasma HMGB1 correlated negatively with platelet counts in ITP patients, and confirmed that 18β-GA stimulated the production of regulatory T cells (Treg), restored the balance of CD4+ T-cell subsets and enhanced the suppressive function of Treg through blocking the effect on HMGB1 in patients with ITP. HMGB1 short hairpin RNA interference masked the effect of 18β-GA in Treg of ITP patients. Furthermore, we found that 18β-GA alleviated thrombocytopenia in mice with ITP. Briefly, anti-CD61 immune-sensitized splenocytes were transferred into severe combined immunodeficient mice to induce a murine model of severe ITP. The proportion of circulating Treg increased significantly, while the level of plasma HMGB1 and serum antiplatelet antibodies decreased significantly in ITP mice along 18β-GA treatment. In addition, 18β-GA reduced phagocytic activity of macrophages towards platelets both in ITP patients and ITP mice. These results indicate that 18β-GA has the potential to restore immune balance in ITP via inhibition of HMGB1 signaling. In short, this study reveals the role of HMGB1 in ITP, which may serve as a potential target for thrombocytopenia therapy.

The effect of short-term air pollutants exposure on outpatient admission for blepharitis in Shanghai, China: a hospital-based study

Blepharitis is a very common ophthalmologic disease, and few studies have examined if air pollutants contribute to the risk of blepharitis. We investigated the presence of any potential correlation between exposure to air pollution and outpatient admission for blepharitis in Shanghai, China. Data on daily outpatient admission for blepharitis were collected from January 2017 to July 2022. Air pollution and meteorological data were acquired from the Shanghai Environmental Protection Agency. Using the distributed lag non-linear model (DLNM) we investigated the relationship between air pollutants and blepharitis. Seasonal stratified analysis was carried out. In total, 10,681 blepharitis patients were recruited. In the single-pollutant model, a 10 μg/m³ increase in particulate matter with < 2.5 μm PM_2.5 and 10 μm PM₁₀ along with sulfur dioxide (SO₂) and 100 μg/m³ increase in carbon monoxide (CO) was significantly associated with outpatient visits for blepharitis. In the multi-pollutant model, a 10 μg/m³ increase in ozone (O₃) and nitrogen dioxide (NO₂) and a 100 μg/m³ increase in carbon monoxide (CO) was significantly associated with outpatient visits for blepharitis. Moreover, there was an obvious relationship between blepharitis and PM_2.5 and O₃ in the summers and blepharitis and PM₁₀, NO₂, and SO₂ during the winters. Exposure to short-term air pollution increases the risk of blepharitis outpatient visits in Shanghai, China.

Microbial-Catalyzed Baeyer-Villiger Oxidation for 3,4-seco-Triterpenoids as Potential HMGB1 Inhibitors

Pentacyclic triterpenoids are considered to be the potential HMGB1 inhibitors, but due to the limited number of hydrogen bond donors and the number of rotatable bonds in the rigid skeletons, their further chemical biology research with this target was restricted. To improve these profiles, microbial-catalyzed Baeyer-Villiger oxidation of the primary ursane and oleanane-type triterpenoids including uvaol (1), erythrodiol (2), oleanolic acid (3), and ursolic acid (4) was performed by Streptomyces olivaceus CICC 23628. As a result, ten new and one known A-ring cleaved metabolites were obtained and the possible biogenetic pathways were also discussed based on the HPLC-MS analysis. Furthermore, the direct interactions between compounds 1d, 2b, and HMGB1 were observed by the biolayer interferometry technique. Molecular docking revealed that the newly introduced vicinal diol at C-4, C-24, and the hydroxyl group at C-21 of compound 1d are crucial for binding with HMGB1. The cellular assay showed that co-treatment of 1d could significantly block HMGB1-activated nitric oxide release with an IC₅₀ value of 9.37 μM on RAW 264.7 cells. Altogether, our research provides some insights into 3,4-seco-triterpenes as potential anti-inflammatory candidates for the discovery of novel HMGB1 inhibitors.

Impact of Low Humidity on Damage-associated Molecular Patterns at the Ocular Surface during Dry Eye Disease

SIGNIFICANCE

Dry eye is one of the leading causes for individuals to seek eye care, whereas the pathogenesis is poorly understood. One mechanism in which dry eye inflammation may ensue is by the release of damage-associated molecular patterns (DAMPs) by damaged cells to stimulate the production of cytokines and matrix metalloproteinases. Examining DAMP levels on the ocular surface during dry eye disease (DED) will increase our understanding of their potential involvement in the pathogenesis of DED.

PURPOSE

This study aimed to quantitate DAMPs, high-mobility group box 1 (HMGB1), and heat shock proteins on the ocular surface of normal and dry eye subjects and to examine the impact of low-humidity environment (LHE) on DAMPs and inflammation in dry eye subjects.

METHODS

Basal tears (10 to 20 μL) and conjunctival impression cytology samples were analyzed for HMGB1, HSP-27, HSP-60, HSP-70, and HSP-90α by ELISA or Luminex assays in normal (n = 15) and DED (n = 15) subjects. In addition, a subset of DED subjects were exposed to LHE for 2 hours. The level of DAMPs in the tear film was evaluated by ELISA or Luminex assay. Interleukin 6, interleukin 8, or metalloproteinase (MMP) 9 mRNA were quantitated by real-time polymerase chain reaction from conjunctival impression cytology samples.

RESULTS

Compared with age-matched normal subjects, HMGB1 was significantly elevated in the tear film of DED subjects (P = .03), whereas there was no significant difference in heat shock proteins. Conjunctival impression cytology samples revealed no significant difference in intracellular DAMP levels between both groups. After exposure to an LHE, there was an increase in corneal staining (P = .005), HSP-60 levels in the tear film (P = .01), and MMP-9 mRNA in the conjunctiva (P = .001).

CONCLUSIONS

Dry eye subjects had higher levels of HMGB1 in their tear film. Exposure to an LHE worsened corneal staining, increased conjunctival MMP-9 mRNA expression, and increased tear film HSP-60 levels. Larger studies are needed to understand the involvement of DAMPs in stimulating dry eye inflammation.

Glycyrrhizin micelle as a genistein nanocarrier: Synergistically promoting corneal epithelial wound healing through blockage of the HMGB1 signaling pathway in diabetic mice

The purpose of this study was to explore the feasibility of targeting the HMGB1 signaling pathway to treat diabetic keratopathy with a dipotassium glycyrrhizinate-based micelle ophthalmic solution encapsulating genistein (DG-Gen), and to evaluate whether these dipotassium glycyrrhizinate (DG) micelles could synergistically enhance the therapeutic effect of encapsulated genistein (Gen). An optimized DG-Gen ophthalmic solution was fabricated with a Gen/DG weight of ratio 1:15, and this formulation featured an encapsulation efficiency of 98.96 ± 0.82%, and an average particle size of 29.50 ± 2.05 nm. The DG-Gen ophthalmic solution was observed to have good in vivo ocular tolerance and excellent in vivo corneal permeation, and to remarkably improve in vitro antioxidant activity. Ocular topical application of the DG-Gen ophthalmic solution significantly prompted corneal re-epithelialization and nerve regeneration in diabetic mice, and this efficacy might be due to the inhibition of HMGB1 signaling through down-regulation of HMGB1 and its receptors RAGE and TLR4, as well as inflammatory factor interleukin (IL)-6 and IL-1β. In conclusion, these data showed that HMGB1 signaling is a potential regulation target for the treatment of diabetic keratopathy, and novel DG-micelle formulation encapsulating active agents such as Gen could synergistically cause blockage of HMGB1 signaling to prompt diabetic corneal and nerve wound healing.

Structure-based design of glycyrrhetinic acid derivatives as potent anti-sepsis agents targeting high-mobility group box-1

Novel Glycyrrhetinic Acid (GA) derivatives with fused heterocycles on A ring were structure-based designed and synthesized. Their potential anti-inflammatory effects were investigated by a classical LPS stimulated macrophage model. Surface plasmon resonance (SPR) was used to verify the binding of GA analogues with HMGB1. A preliminary structure-activity relationship was summarized and an analogue GA-60 with ortho-methoxybenzyl pyrozole showed stronger anti-inflammatory effect and higher affinity for HMGB1 with a K_d value of 12.5 μM. In addition, this compound exhibited excellent inhibitory functions on NO (96%), TNF-α (94%), and IL-6 (100%), by interfering with phosphorylation of p38, ERK, JNK MAPKs, as well as that of NF-κB p65 and IKKα/β. Moreover, GA-60 extended the survival of either the classic CLP-induced or LPS-induced sepsis mouse models. Molecular modeling predictions further supported these findings, clearly indicating that inhibiting HMGB1 release, using fused heterocyclic GA derivatives, is a promising strategy for treatment of sepsis.

The effect of astaxanthin on inflammation in hyperosmolarity of experimental dry eye model in vitro and in vivo

Hyperosmolarity is pro-inflammatory stress to the ocular surface epithelium associated with dry eye disease (DED). Astaxanthin (AST) is a kind of carotene, which exists in seafood and plays important roles in the amelioration of inflammatory diseases like arteriosclerosis, inflammatory bowel disease, sepsis, rheumatoid arthritis, gastric inflammation, brain inflammatory diseases. The aim of this study was to characterize the protective effect and potential mechanism of AST on DED in vitro and in vivo. Mouse models and human corneal epithelial cell (HCEC) cultures were exposed to hyperosmotic saline solution (HOSS) in in vitro and in vivo experiments, respectively. Experimental subjects were first pretreated with AST, and then the effect of the compound was assessed with clinical evaluation, real-time PCR (RT-PCR), western blot and immunofluorescent staining. We further investigated the possible mechanism of AST in DED by pre-treating with phosphoinositide 3-kinase inhibitor (LY294002). The addition of AST significantly reduced the expression of High-mobility group box 1 (HMGB1), as well as significantly inhibited the increases of TNF-α, IL-1β in a dose-dependent manner, but promoted the expression of phospho-Akt (p-Akt). BALB/c mice in DE group pretreated with AST showed significantly decreased corneal fluorescein staining scores. Moreover, pretreatment with LY294002 could eliminate the effects of AST preconditioning on the decrease of HMGB1. Our study provides evidence that AST could ameliorate DED which may be related to the inhibition of HMGB1, TNF-α, IL-1β, while PI3K/Akt signaling pathway may be involved in the expression of HMGB1 and the protective effect of AST preconditioning.

Alarmin HMGB1 Plays a Detrimental Role in Hippocampal Dysfunction Caused by Hypoxia-Ischemia Insult in Neonatal Mice: Evidence from the Application of the HMGB1 Inhibitor Glycyrrhizin

Hippocampal dysfunction related to cognitive impairment and emotional disorders in young children and adolescents caused by neonatal hypoxic-ischemic brain injury (HIBI) has attracted increasing attention in recent years. Crosstalk between the nervous and immune systems organized by hypoxia-ischemia (HI) insult may contribute to hippocampal dysfunction after HIBI. Extracellular HMGB1 functions as a damage-associated molecular pattern to instigate and amplify inflammatory responses, but whether this molecule is correlated with hippocampal dysfunction after HIBI is largely unknown. Therefore, this study examined hippocampal function after HMGB1 inhibition in an experimental HIBI model to verify the hypothesis that HMGB1 is a key mediator of hippocampal neuropathology in neonatal HIBI. By administering different doses of the HMGB1-specific inhibitor glycyrrhizin (GLY), we first found that GLY reversed the HI insult-induced loss of neurons and myelin in the hippocampal region and neurobehavioral impairments, partially in a dose-dependent manner, and based on this, we determined the optimal drug concentration to be 50 mg/kg. Subsequent analysis found that this neuroprotective effect was achieved through the inhibition of HMGB1 expression and nucleocytoplasmic translocation, a reduction in the abnormal expression of proteins associated with the downstream signaling pathway of HMGB1, a decrease in the inflammatory response, the suppression of increases in microglia/astrocytes, and the inhibition of hippocampal cell apoptosis. Collectively, our discoveries contribute to the rising appreciation of the role of HMGB1 in the neuropathology of hippocampal dysfunction and related behavioral outcomes following HIBI.

Glycyrrhizin Use for Multi-Drug Resistant Pseudomonas aeruginosa: In Vitro and In Vivo Studies

Purpose

Our purpose was to test glycyrrhizin (GLY) effects and ciprofloxacin interactions on multidrug resistant (MDR) isolates of Pseudomonas aeruginosa in vitro and in vivo in a mouse model of keratitis.

Methods

A Hardy-disk tested antibiotic sensitivity of isolates MDR9 (nonocular) and B1045 (ocular). GLY MIC (both isolates) and ciprofloxacin was determined spectrophotometrically. A live/dead assay using confocal microscopy and plate count, tested GLY effects on bacterial permeabilization/viability. Proteomics profiled bacterial efflux pumps (MDR9 vs. PAO1); RT-PCR comparatively tested GLY effects on their mRNA expression levels. The activity of efflux pumps was tested using ethidium bromide (EB); and scanning electron microscopy (SEM) visualized the effects of GLY treatment of bacteria. A combination of GLY and ciprofloxacin was tested in C57BL/6 mice (begun 18 hours after infection) and disease scored, photographed and MPO and plate counts done.

Results

MDR9 was resistant to 6/12 and B1045 to 7/12 antibiotics (both to ciprofloxacin). MIC GLY for MDR9 was 40 mg/mL and 15 mg/mL for B1045. Ciprofloxacin MIC (32 μg/mL) was reduced 2-fold to 16 μg/mL when ciprofloxacin and GLY were combined. GLY altered bacterial membrane permeability and reduced viability. Proteomics revealed increased efflux pumps in MDR9 versus PAO1; GLY reduced their mRNA expression levels and EB suggested decreased activity. In C57BL/6 mice, treatment with GLY and ciprofloxacin versus ciprofloxacin, significantly reduced clinical scores, plate count, and MPO.

Conclusions

GLY decreases MDR by: altering bacterial parameters, including viability and efflux pump activity. In vivo, it increases the effectiveness of ciprofloxacin, reducing ocular disease, plate count, and MPO activity.

High-Mobility Group Box 1 in Dry Eye Inflammation

Purpose

To determine high-mobility group box 1 (HMGB1) expression during experimental dry eye (EDE) and dry eye-like culture conditions and elucidate its role in corneal dry eye-related inflammation.

Methods

EDE was induced in 8- to 12-week-old C57BL/6 mice. Corneal tissue sections and lysates from EDE and untreated mice were evaluated for HMGB1 expression by immunostaining and quantitative real-time PCR (qPCR). For in vitro studies, human corneal epithelial cells (HCEC) were treated with hyperosmolar media, toll-like receptor (TLR) agonists, or proinflammatory cytokines to determine HMGB1 expression. HCEC were also treated with human recombinant HMGB1 (hrHMGB1) alone or in combination with inflammatory stimuli, and TNFα, IL-6, and IL-8 expression evaluated by qPCR and ELISA. Nuclear factor-κB (NF-κB) p65 nuclear translocation was determined by immunostaining.

Results

EDE mice had higher corneal HMGB1 RNA and protein expression compared to untreated animals. In HCEC, hyperosmolar stress and TNFα treatment stimulated HMGB1 production and secretion into culture supernatants. However, in vitro stimulation with hrHMGB1 did not induce secretion of TNFα, IL-6, or IL-8 or NF-κB p65 nuclear translocation. In addition, the inflammatory response elicited by TLR agonists fibroblast-stimulating lipopeptide-1 and lipopolysaccharide was not enhanced by hrHMGB1 treatment.

Conclusions

HMGB1 expression was enhanced by dry eye conditions in vivo as well as in vitro, during hyperosmolar stress and cytokine exposure, suggesting an important role for HMGB1 in dry eye disease. However, no direct inflammatory effect was observed with HMGB1 treatment. Therefore, under these conditions, HMGB1 does not contribute directly to dry eye-induced inflammation and its function at the ocular surface needs to be explored further.

Efficacy and safety of glycyrrhizin 2.5% eye drops in the treatment of moderate dry eye disease: results from a prospective, open-label pilot study

Background

Dry eye disease (DED) is characterized by a loss of homeostasis of the tear film. It goes along with ocular symptoms, in which ocular surface inflammation and damage play etiological roles. High-mobility group box 1 protein (HMGB1) is a pro-inflammatory protein found in the tear fluid during conjunctivitis, blepharitis and DED. Glycyrrhizin binds to HMGB1, inhibiting cytokine activities, thus potentially improving DED.

Aim

To assess the efficacy and tolerance of glycyrrhizin in moderate DED.

Methods

Multicenter, open-label, prospective, nonrandomized clinical pilot study of glycyrrhizin 2.5% eye drops twice daily over 28 days in adult patients with moderate DED using standard evaluation parameters.

Results

The overall mean age of the 37 patients included was 59.6±19.0 years, 70.3% of the patients were female and 77.0% of the patients had an Oxford score of II. After 28 days, 60.8% of the patients had an Oxford score of 0 or I; a significant mean improvement in the score of 0.97±0.86 (P<0.001) from 2.20±0.44 at day 1 to 1.23±0.88 at day 28 was observed. Tear break-up time and Schirmer scores had significantly improved while the number of patient-reported symptoms had significantly decreased (all P≤0.010). A large majority of patients still had a few spots on their naso-bulbar conjunctiva (86.1%), temporal-bulbar conjunctiva (81.4%) and cornea (84.7%). The investigators considered that DED had improved in 71.6% of the patients. Patients appreciated the eye drops for their efficacy and good tolerance profile, leading to a decreased use of artificial tears. No changes in intraocular pressure and visual acuity were observed; glycyrrhizin 2.5% eye drops were safe, with only one patient reporting a moderate, transient treatment-related contact allergy leading to the withdrawal of the patient. Overall, two patients reported three adverse events, two (moderate contact allergy in both eyes) were related to the eye drops and experienced by the same patient; treatment was stopped; the third event was not treatment-related.

Conclusion

In this pilot study, glycyrrhizin 2.5% eye drops were well tolerated and provide a good clinical benefit to patients with moderate DED after 28 days of continued daily use.

Increased Lacrimal Fluid Level of HMGB1 in Vernal Keratoconjunctivitis

Purpose: The aim of the present prospective study was to evaluate the lacrimal fluid concentration of HMGB1 in young patients affected by Vernal Keratoconjunctivitis (VKC) compared to a control group of healthy subjects of same age. Methods: Tear fluids was collected in a group of VKC patients and compared to a control group of healthy subjects. HMGB1 concentration was measured using the HMGB1 ELISA II test both in VCK and control subjects. Results: The mean concentration of HMGB1 in tear fluids of 45 VKC patients was 0,977 ± 0,72 ng/ml whereas in the control group was 0,24 ± 0,25 ng/ml and the difference was statistically significant (p = 0,000106) Conclusion: The concentration of HMGB1 in VCK patients was found to be significantly increased, suggesting a possible role of this protein in the inflammatory mechanism of VKC.

Characterization of Three Ocular Clinical Isolates of P. aeruginosa: Viability, Biofilm Formation, Adherence, Infectivity, and Effects of Glycyrrhizin

We selectively characterized three isolates from Pseudomonas aeruginosa keratitis patients and how glycyrrhizin (GLY) affected them. Type III toxins were determined using polymerase chain reaction (PCR). Minimum Inhibitory Concentration (MIC) of GLY and assays for its effects on: time kill, bacterial permeability, and biofilm/adhesion were done. In vivo, C57BL/6 (B6) mice were treated topically with GLY after G81007 infection. Clinical score, photography with a slit lamp and RT-PCR were used to assess treatment effects. Isolates expressed exoS and exoT, but not exoU. MIC for all isolates was 40 mg/mL GLY and bacteriostatic effects were seen for G81007 after treatment using time kill assays. From viability testing, GLY treatment significantly increased the number of permeabilized bacteria (live/dead assay). Isolates 070490 and G81007 formed more biofilms compared with R59733 and PAO1 (control). GLY-treated bacteria had diminished biofilm compared with controls for all isolates. GLY reduced adherence of the G81007 isolate to cultured cells and affected specific biofilm associated systems tested by reverse transcription PCR (RT-PCR). In vivo, after G81007 infection, GLY treatment reduced clinical score and messenger RNA (mRNA) expression of IL-1β, TNF-α, CXCL2 and HMGB1. This study provides evidence that GLY is bacteriostatic for G81007. It also affects biofilm production, adherence to cultured cells, and an improved keratitis outcome.

Cytokine expression and barrier disruption in human corneal epithelial cells induced by alarmin released from necrotic cells

PURPOSE

Dying cells release endogenous molecules known as alarmins that signal danger to surrounding tissue. We investigated the effects of necrotic cell-derived alarmins on cytokine expression and barrier function in human corneal epithelial cells.

METHODS

The release of interleukin (IL)-6 and IL-8 from immortalized human corneal epithelial (HCE) cells in culture was measured with enzyme-linked immunosorbent assays. The abundance of IL-6 and 8 mRNAs was quantitated by reverse transcription and real-time polymerase chain reaction analysis. Barrier function of HCE cells was evaluated by measurement of transepithelial electrical resistance (TER). The subcellular localization of the p65 subunit of the transcription factor NF-κB was determined by immunofluorescence analysis, and phosphorylation of the endogenous NF-κB inhibitor IκBα was examined by immunoblot analysis.

RESULTS

A necrotic cell supernatant prepared from HCE cells induced the up-regulation of IL-6 and 8 expression at both mRNA and protein levels as well as reduced TER in intact HCE cells. Among alarmins tested, only IL-1α (not IL-33 or HMGB1) mimicked these effects of the necrotic cell supernatant. Furthermore, IL-1 receptor antagonist (IL-1RA) and neutralizing antibodies to IL-1α (but not those to IL-1β) each attenuated the effects of the necrotic cell supernatant. Exposure of HCE cells to the necrotic cell supernatant also induced the phosphorylation and degradation of IκBα as well as translocation of the p65 subunit of NF-κB to the nucleus.

CONCLUSION

IL-1α released from necrotic corneal epithelial cells may trigger inflammatory responses at the ocular surface, including cytokine production and barrier disruption.

Glycyrrhizin Reduces HMGB1 and Bacterial Load in Pseudomonas aeruginosa Keratitis

Purpose

High mobility group box 1 (HMGB1) contributes to poor disease outcome in Pseudomonas aeruginosa keratitis. This study tests the prophylactic effect of treatment with HMGB1 inhibitors, glycyrrhizin (GLY) and its derivative, carbenoxolone (CBX), for Pseudomonas keratitis.

Methods

We treated C57BL/6 (B6) mice subconjunctivally with GLY or CBX, infected with a noncytotoxic clinical isolate (KEI 1025) or a cytotoxic strain (ATCC 19660) of P. aeruginosa, and injected intraperitoneally with either agent. Clinical score, photography with a slit lamp, real-time RT-PCR, ELISA, myeloperoxidase (MPO) assay, bacterial plate count, histopathology, and absorbance assays were used to assess treatment efficacy and bacteriostatic activity.

Results

After KEI 1025 infection, GLY treatment reduced HMGB1 (mRNA and protein levels) and improved disease outcome with significant reduction in mRNA levels of IL-1β, TLR4, CXCL2, and IL-12; protein expression (IL-1β, CXCL2); neutrophil infiltrate; and bacterial load. Treatment with GLY enhanced antimicrobial proteins, including CRAMP and mBD2, but not mBD3. Glycyrrhizin also reduced clinical scores and improved disease outcome in corneas infected with strain 19660. However, neither HMGB1 mRNA or protein levels were reduced, but rather, CXCL2 expression (mRNA and protein), neutrophil infiltrate, and bacterial load were reduced statistically. Treatment with GLY initiated 6 hours after infection reduced plate count; GLY also was bacteriostatic for KEI 1025 and ATCC 19660.

Conclusions

Glycyrrhizin reduces HMGB1 and is protective against P. aeruginosa-induced keratitis with a clinical isolate that is noncytotoxic. It was similar, but less effective when used after infection with a cytotoxic strain, which did not reduce HMGB1.

Increase in the Level of Proinflammatory Cytokine HMGB1 in Nasal Fluids of Patients With Rhinitis and its Sequestration by Glycyrrhizin Induces Eosinophil Cell Death

OBJECTIVES

The nuclear protein high mobility group protein box 1 (HMGB1) is a proinflammatory mediator that belongs to the alarmin family of proinflammatory mediators, and it has recently emerged as a key player in different acute and chronic immune disorders. Several lines of evidence demonstrate that HMGB1 is actively released extracellularly from immune cells or passively released from necrotic cells. Because of the ability of HMGB1 to sustain chronic inflammation, we investigated whether the protein is present in nasal fluids of patients with different forms of rhinitis.

METHODS

HMGB1 levels were evaluated in nasal fluids of healthy subjects or rhinitis patients who were treated or not treated with different treatments.

RESULTS

We report that the level of HMGB1 was significantly increased in nasal fluids of patients with allergic rhinitis, patients with NARES (nonallergic rhinitis with eosinophiliac syndrome), as well as patients with polyps. We also found that a formulation containing the HMGB1-binding compound glycyrrhizin (GLT) reduced the HMGB1 content in nasal fluids of rhinitis patients to an extent similar to that with nasal budesonide treatment. We also found that among the cultured human leukocyte populations, eosinophils released higher amounts of HMGB1. Based on the ability of HMGB1 to sustain eosinophil survival and the ability of GLT to inactivate HMGB1, we report that GLT selectively killed cultured eosinophils and had no effect on neutrophils, macrophages, and lymphocytes.

CONCLUSION

Collectively, these data underscore the role of HMGB1 in rhinitis pathogenesis and the therapeutic potential of GLT formulations in treatment of chronic inflammatory disorders of the nasal mucosa.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Allergic Rhinitis in Children: A Randomized Clinical Trial Targeted at Symptoms

Allergic rhinitis (AR) underlies many symptoms and complications which severely affect children's quality of life. This two-arm study aimed at evaluate the efficacy and safety of the medical device Narivent(®) versus topical corticosteroids in the symptomatic management of allergic rhinitis in paediatric patients. A randomized study was conducted. Forty subjects with a diagnosis of allergic rhinitis were randomized to receive one puff of Narivent(®) into each nostril twice daily for 30 days (n = 20) or to receive one puff of topical intranasal corticosteroid into each nostril twice daily for 30 days (n = 20). In both treatment arms, severity of major symptoms related to AR, including nasal congestion, rhinorrhoea, sneezing and nasal itching, was assessed subjectively on a 0-100 mm visual analogue scale. Nasal congestion, rhinorrhoea and sneezing improved significantly after 30 days of treatment with Narivent(®). Similarly, in topical steroids group severity of all subjective symptoms decreased significantly. Narivent(®) appears to be efficacious in treating nasal congestion and other major symptoms in children with AR over a 30-day period, showing comparable results to intranasal corticosteroids therapy but with a better safety profile.

Assessment of the tolerability profile of an ophthalmic solution of 5% glycyrrhizin and copolymer PEG/PPG on healthy volunteers and evaluation of its efficacy in the treatment of moderate to severe blepharitis

Purpose

To evaluate the tolerability on healthy volunteers and the efficacy on subjects affected by chronic moderate/severe blepharitis of a 5% glycyrrhizin and copolymer poly(ethylene glycol)/poly(propylene glycol)(PEG/PPG) ophthalmic solution.

Methods

The study was a randomized, controlled, open label, intra-patient monocentric study. It consisted of two different phases, the assessment of tolerability phase on 20 healthy volunteers, and the evaluation of the efficacy on 21 subjects affected by chronic moderate/severe blepharitis; the treatment period was 2 weeks, followed by 1-week of follow-up. In the efficacy phase, in both eyes, eyelid hygiene was also performed. At day 0, 3, 7, 14, and 21 a complete ophthalmological examination was performed. In the tolerability phase, signs of clinical toxicity were recorded and subject-reported symptoms were collected using a questionnaire. In the efficacy phase, global signs and symptoms of blepharitis scores were collected using standardized photographic scales and questionnaire. The statistical analysis was performed using the Wilcoxon signed-rank test.

Results

No ocular signs of drug toxicity were reported. During the treatment period for tolerability phase, there were statistically significant higher scores of tearing and ocular discomfort in the tolerability study group versus the tolerability control group. In the efficacy phase, differences between global scores of the two groups were statistically significant at day 0 (score of the efficacy study group was higher than the efficacy control group; P = 0.005) and at day 21 (score of the efficacy study group was lower than the efficacy control group (P ≤ 0.001).The difference of global scores at day 3, 7, 14, and 21 versus day 0 was statistically significant in both groups. No serious adverse events occurred.

Conclusion

The 5% glycyrrhizin ophthalmic solution was well tolerated in healthy volunteers and in patients with chronic moderate/severe blepharitis, and in association with eyelid hygiene showed good clinical anti-inflammatory activity that lasted after instillation suspension.

HMGB1: A Promising Therapeutic Target for Prostate Cancer

High mobility group box 1 (HMGB1) was originally discovered as a chromatin-binding protein several decades ago. It is now increasingly evident that HMGB1 plays a major role in several disease conditions such as atherosclerosis, diabetes, arthritis, sepsis, and cancer. It is intriguing how deregulation of HMGB1 can result in a myriad of disease conditions. Interestingly, HMGB1 is involved in cell proliferation, angiogenesis, and metastasis during cancer progression. Furthermore, HMGB1 has been demonstrated to exert intracellular and extracellular functions, activating key oncogenic signaling pathways. This paper focuses on the role of HMGB1 in prostate cancer development and highlights the potential of HMGB1 to serve as a key target for prostate cancer treatment.