The IL-31/TRPV1 pathway mediates allergic asthma exacerbated by DINP dermal exposure in OVA-sensitized Balb/c mice

BACKGROUND

The potential role of dermal exposure diisononyl phthalate (DINP) as an adjuvant in allergic inflammation and asthma has been suggested. However, the current findings do not provide enough evidence to support this claim.

OBJECTIVES

The purpose of this investigation was to examine the impact and mechanisms of allergic asthma exacerbation through the dermal exposure to DINP.

METHODS

The study was undertaken using OVA-sensitized mice. Lung histopathology and airway hyperreactivity (AHR) were assessed. Expression levels of immunoglobulins (t-IgE, OVA-IgE and OVA-IgG1), cytokines (IL-31, IL-4, IL-5, IL-6, IL-13 and INF-γ), and TRPV1 were measured. To investigate the mechanism by which allergic asthma worsens due to dermal exposure to DINP, the blockade analysis using the IL-31 antagonist SB-431542 and the TRPV1 antagonist capsazepine (CZP) were performed.

RESULTS

The findings of the study revealed that the simultaneous exposure to DINP and OVA resulted in an increase in inspiratory resistance (Ri) and expiratory resistance (Re), a decrease in the minimum value of lung dynamic compliance (Cldyn), and worsened airway remodeling. Additionally, it was found that this exposure led to an increase in the levels of IL-31 and TRPV1, which are biomarkers of Th2 cytokines (IL-4, IL-5, IL-6, and IL-13), as well as immunoglobulins (Total IgE, OVA-lgE, and OVA-IgG1), while decreasing the biomarker of Th1 cytokines (IFN-γ). However, these impairments showed improvement after the administration of SB-431542 or CZP.

CONCLUSION

The findings of this research indicate that the IL-31/TRPV1 pathway plays a moderating function in OVA-induced allergic asthma worsened by dermal exposure to DINP.

Di-(2-ethylhexyl) phthalate aggravates fine particulate matter-induced asthma in weanling mice due to T follicular helper cell-dependent response

Environmental pollutants fine particulate matter and di-(2-ethylhexyl) phthalate (DEHP) are believed to be the risk factors for childhood asthma. Allergic asthma is basically an immediate hypersensitivity mediated by IgE, the product of humoral immune response. T follicular helper cells (Tfh) have been newly identified as the crucial T helper cells for supporting B cells to produce immunoglobulins in humoral immunity. Tfh cells are therefore potentially to serve as the diagnostic marker and therapeutic target of immune diseases. In this study, we examined the joint effects of fine particulate matter and DEHP on the initiation and progression of asthma and explored the fundamental role of Tfh cells during the process. Weanling C57BL/6 mice (both sexes) were concurrently exposed to DEHP (intragastric administration at 300 μg/kg) and fine atmospheric particulate matter (mean particle diameter < 4 µm, PM4) (oropharyngeal instillation at 2 mg/kg) once every three days for 30 days (10 times). We found that DEHP displayed adjuvant effects to potentiate PM4 allergen-induced expansion of Tfh and plasma cells, production of serum IgE and IgG1, and occurrence of airway hyper-responsiveness and inflammation. Then PM4 and DEHP co-exposure was performed to Cd4 knock-out mice reconstituted with normal wild-type adoptive Tfh cells or non-Tfh cells. The results of immune adoptive transfusion indicated that the joint immunotoxic effects of PM4 and DEHP were dependent on Tfh cells. We further proved that DEHP could adjuvantly boost PM4-induced expression of BCL-6 and c-MAF and secretion of IL-13 and IL-4 in Tfh cells. In conclusion, these data suggest that DEHP metabolites act in an adjuvant-like manner to aggravate PM4 allergen-induced asthma based on anaphylactic IgE response, resulting from excessive IL-13 and IL-4 synthesized by abnormally differentiated Tfh cells.

[Effects of glycyrrhizin on airway mucus hypersecretion induced by interleukin-13 in rats]

OBJECTIVE

To explore the effects of glycyrrhizin on airway mucus hypersecretion induced by interleukin-13 (IL-13) in rats.

METHODS

A total of 50 SD rats were divided randomly into 5 groups with a random digit table: control group, IL-13 group, and different dosage (25, 50, 75 mg/kg) glycyrrhizin groups. The integral of expression intensity in positive cells of airway epithelium under mucus histochemical stain was calculated with modality-quantitative method. HBE-16 cells were divided into 6 groups: negative control (physiological saline), IL-13 control (10 µg/L IL-13+physiological saline), different concentration glycyrrhizin interference (10 µg/L IL-13+25, 50 and 75 µmol/L glycyrrhizin, respectively) and positive control (10 µg/L IL-13+25 µmol/L zopolrestat). The expression of mucin (MUC) 5AC mRNA, MUC5AC protein, aldose reductase (AR) activity and reactive oxygen species (ROS) content were detected by reverse transcription-polymerase chain reaction (RT-PCR), Western blot, fluorometric method and fluorescence intensity with General Oxidative Stress Indicator (CM-H2DFDA) catheter respectively.

RESULTS

In vivo, the integral of expression intensity in positive stain cells of airway epithelium were 0.12 ± 0.03, 0.87 ± 0.13, 0.56 ± 0.08, 0.46 ± 0.06 and 0.35 ± 0.04 respectively while the integral of different dosage glycyrrhizin groups was significantly lower than that of IL-13 group (all P < 0.05) with dose depentency and the IL-13 group was stronger than control group (P < 0.05). In vitro, the index of AR activity and ROS at 48 h of HBE16 cells in every group were 0.156 ± 0.021, 0.692 ± 0.039, 0.436 ± 0.019, 0.323 ± 0.042 and 0.290 ± 0.027; 5.127 ± 0.033, 24.257 ± 3.263, 11.966 ± 0.283, 8.892 ± 0.521 and 6.426 ± 0.173 respectively. The indices of IL-13 control group were higher than those of negative control group (P < 0.05) while those of different concentration glycyrrhizin interference groups were lower than those of IL-13 control group (all P < 0.05). The expressions of MUC5AC mRNA and protein of HBE16 cells in every group were 0.82 ± 0.05, 3.22 ± 0.12, 2.57 ± 0.34, 2.09 ± 0.54 and 1.58 ± 0.22; 0.18 ± 0.04, 0.65 ± 0.15, 0.48 ± 0.11, 0.33 ± 0.19 and 0.26 ± 0.06 respectively. The indices of IL-13 control group were higher than those of negative control group (P < 0.05) and those of different concentration glycyrrhizin interference groups were lower than those of IL-13 control group (P < 0.05).

CONCLUSION

Glycyrrhizin may inhibit the expression of MUC5AC mRNA and MUC5AC protein induced by IL-13 and control the hypersecretion of airway mucus.

Convection-enhanced delivery of interleukin-13 receptor-directed cytotoxin for malignant glioma therapy

The treatment of patients with malignant brain tumors, in particular glioblastoma multiforme (GBM) is very challenging because of their diffuse infiltrative nature and the cytological heterogeneity. The median survival of patients with newly diagnosed GBM is only 12-15 months, and only 8-12% of them survive for two years. Novel approaches for brain tumor therapy are needed. Recently, targeted therapies have emerged as promising modality for cancer targeting. We have discovered that high affinity plasma membrane receptor for interleukin-13 (IL-13), an immune regulatory cytokine, is over-expressed in 60-80% of malignant brain tumors. To target these IL-13R, we generated a chimeric fusion protein, composed of human IL-13 and mutated Pseudomonas exotoxin (PE), termed IL-13 cytotoxin (IL13-PE), and tested its cytotoxicity to IL-13R-expressing GBM cells. IL-13 cytotoxin was highly potent and selective in killing IL-13R-expressing GBM cells. In contrast, normal cells including brain, immune, and endothelial cells were generally not affected by this cytotoxin due to no or low expression of IL-13R. In vivo pre-clinical studies for safety and toxicity were also performed in mice, rats, and monkeys, and IL-13 cytotoxin was found to be well tolerated by both systemic and intracerebral administrations. IL-13 cytotoxin was found to mediate remarkable efficacy in animal models of human brain tumors. Encouraged by these pre-clinical studies, four Phase 1/2 clinical trials in adult patients with recurrent malignant glioma have been completed. These clinical trials involved convection-enhanced delivery (CED) of IL-13 cytotoxin either intratumoral or intraparenchymal after resection of tumor. CED is a novel loco-regional drug delivery method for intracranial tumors that relies on a continuous pressure gradient to distribute drug into interstitial space. This route of IL-13 cytotoxin administration appears to be very well tolerated and have a good risk-benefit profile. Most recently, a randomized controlled Phase 3 clinical trial (PRECISE) with intraparenchymal IL-13 cytotoxin administration was completed and subjects are being monitored for safety and survival.

Technology evaluation: cintredekin besudotox, NeoPharm/Nippon

NeoPharm Inc, under license from the National Institutes of Health and the FDA, and in collaboration with the Japanese licensee Nippon Kayaku Co Ltd, is developing cintredekin besudotox, a chimeric human IL-13 conjugated to a genetically engineered Pseudomonas exotoxin molecule, as a potential antitumor agent. This agent is currently undergoing phase III clinical trials.

Long-term exacerbation by interleukin 13 of IgE-mediated eosinophilia in rats

Recent work shows that at least two cycles of antigen challenge applied in a 7-day interval are required to yield tissue eosinophil accumulation in IgE-passively sensitized rats. Since interleukin (IL)-13 is widely regarded as a key mediator in eosinophilic responses associated with mast cells and IgE, we investigated whether this cytokine could replace the first cycle of sensitization and challenge in its proeosinophilic role. We found that IL-13 (25 and 50 ng/cavity) injected into the rat pleural space led to eotaxin generation and a dose-dependent accumulation of eosinophils following IgE-passive sensitization and challenge 7 days later. IL-13 failed to cause eosinophil chemotaxis in vitro but induced eosinophil accumulation into the pleural cavity of naïve rats, which peaked 1 day and faded 72 h post-challenge. No changes were found 1 week after intrapleural injection of IL-13, except an approximately 40-50% increase in the number of adhered and non-adhered pleural mast cells. As recovered from the pleural effluent 1 week after IL-13, mast cells expressed the same amount of IgE bound on their surface as compared to controls. However, they generated 3-fold more LTC(4) following IgE-sensitization and challenge in vitro, keeping intact the amount of histamine released. Finally, pretreatment with zileuton (50 microg/cavity) 1 h before allergen challenge prevented eosinophil accumulation in those animals injected with IL-13 1 week before. In conclusion, our findings show that IL-13 causes a long-term exacerbation of the IgE-mediated eosinophilic response in a mechanism associated with heightened cysteinyl-leukotriene (cys-LT) production by resident mast cells.

Distribution kinetics of targeted cytotoxin in glioma by bolus or convection-enhanced delivery in a murine model

OBJECT

Interleukin-13 receptor (IL-13R)-targeted cytotoxin (IL-13-PE38) displays a potent antitumor activity against a variety of human tumors including glioblastoma multiforme (GBM) and, thus, this agent is being tested in the clinical trial for the treatment of recurrent GBM. In this study, the authors determined the safety and distribution kinetics of IL-13 cytotoxin when infused intracranially by a bolus injection and by convection-enhanced delivery (CED) in an athymic nude mouse model of GBM.

METHODS

For the safety studies, athymic nude mice were given intracranial infusions of IL-13 cytotoxin into normal parenchyma by either a bolus injection or a 7-day-long CED. Toxicity was assessed by performing a histological examination of the mouse brains. For the drug distribution studies, nude mice with intracranially implanted U251 GBM tumors were given an intratumor bolus or a CED infusion of IL-13 cytotoxin. Brain tumor samples obtained between 0.25 and 72 hours after the infusion were assessed for drug distribution kinetics by performing immunohistochemical and Western blot analyses. Based on the histological changes in the tumor and brain, the maximum tolerated dose of intracranial IL-13 cytotoxin infusion in nude mice was determined to be 4 microg when delivered by a bolus injection and 10 microg when CED was used. Drug distribution reached the maximum level 1 hour after the bolus injection and the volume of distribution was determined to be 19.3 +/- 5.8 mm3. Interleukin-13 cytotoxin was barely detectable 6 hours after the injection. Interestingly, when delivered by bolus injections IL-13 cytotoxin exhibited superior distribution in larger rather than smaller tumors. Convection-enhanced delivery was superior for drug distribution in the U251 tumors because when CED was used the drug remained in the tumors 6 hours after the infusion.

CONCLUSIONS

These studies provide confirmation of a previous hypothesis that CED of IL-13 cytotoxin is superior to bolus injections not only for the safety of the normal brain but also for maintaining drug levels for a prolonged period in infused brain tumors. These findings are highly relevant and important for the optimal clinical development of IL-13 cytotoxin or any other targeted antitumor agent for GBM therapy, in which multiple routes of delivery of an agent are being contemplated.

Interstitial infusion of IL13-PE38QQR in the rat brain stem

Interstitial infusion of IL13-PE38QQR, a tumor specific, chimeric cytotoxin, into the rat brain stem was performed in an effort to assess safety. Six rats underwent stereotaxic cannula placement into the pontine segment of the brain stem followed by a 24-h infusion of IL13-PE38QQR (volume of infusion (Vi) 200 microl) at a concentration of 10 microg/ml. The animals were assessed neurologically and then sacrificed either immediately or after 2 weeks. All animals tolerated the infusions without exhibiting any neurological changes. Postmortem examination of the brains revealed no significant histological changes beyond the site of the cannula tract. These findings indicate that supratherapeutic concentrations of IL13-PE38QQR administered by interstitial infusion into the rat brain stem is well tolerated and may serve as a potential therapeutic strategy for children with diffuse pontine gliomas.

IL-13 receptor-targeted cytotoxin cancer therapy leads to complete eradication of tumors with the aid of phagocytic cells in nude mice model of human cancer

Tumor-directed therapeutic approaches require unique or overexpressed specific Ag or receptor as a target to achieve selective tumor killing. However, heterogeneous expression of these targets on tumor cells limits the efficacy of this form of therapy. In this study, we forced abundant expression of IL-13Ralpha2 chain by plasmid-mediated gene transfer in head and neck, as well as prostate tumors to provide a potential target. This was followed by successfully treating xenograft tumor-bearing nude mice with IL-13R-directed cytotoxin (IL13-PE38QQR). Although we did not observe an indirect cytotoxic bystander effect conveyed to nontransduced tumor cells in vitro, our approach in vivo led to a complete regression of established tumors transfected with IL-13Ralpha2 chain in most animals. We found that the tumor eradication was achieved in part by infiltration of macrophages and NK cells, assessed by immunohistochemistry. Moreover, head and neck tumors xenografted in macrophage-depleted nude mice were less sensitive to the antitumor effect of IL-13 cytotoxin. Because we did not observe vector-related toxicity in any vital organs, our novel combination strategy of gene transfer of IL-13Ralpha2 chain and receptor-directed cytotoxin therapy may be a useful approach for the treatment of localized cancer.