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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., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2023. Published by Elsevier B.V.)

This study examines the effect of monoclonal antibody to very late activation antigen-4 (VLA-4) on IL5-induced airway hyperresponsiveness in vivo and eosinophil accumulation into guinea pig airways. IL5 has been shown to be important in the development of airway hyperresponsiveness and eosinophil accumulation in the guinea pig. Eosinophils, unlike neutrophils, express VLA-4 which mediates the adhesion to vascular cell adhesion molecule-1 on endothelial cells. Thus VLA-4 seems to be an important adhesion molecule in the infiltration of eosinophils from the vasculature into the airway tissue. In addition, it has been shown that IL5 activates VLA-4 on eosinophils to facilitate their adhesion. In the present study, IL5 (1 microg, twice on one day) or vehicle were administered intranasally. Monoclonal antibody (mAb) to VLA-4 (HP1/2) or the isotype-matched control mAb (1E6) were injected 1 hour before each IL5 or vehicle treatment at a dose of 2.5 mg/kg body weight. The next day in vivo bronchial reactivity, eosinophil number in bronchoalveolar lavage (BAL) fluid, and eosinophil peroxidase (EPO) activity in cell-free BAL fluid were determined. IL5 induces an increase in bronchial reactivity to histamine, which is associated with an accumulation of eosinophils into BAL fluid (control: 12 (5 to 42) x 10(5) cells and IL5: 69 (11 to 99) x 10(5) cells, p < 0.05) and an increase of 35% +/- 14% in EPO activity in cell-free BAL fluid. Intravenous administration of anti-VLA-4 mAb, but not of the control antibody, completely inhibits the bronchial hyperresponsiveness as well as the airway eosinophilia found after intraairway application of IL5. HP1/2 also suppresses the IL5-induced increase in EPO activity in cell-free BAL fluid. In conclusion, for the development of IL5-induced airway hyperresponsiveness in the guinea pig, the VLA-4-dependent infiltration and activation of eosinophils in the bronchial tissue seems to be essential.

The potency of dexamethasone has been determined as an inhibitor of intratracheally administered platelet activating factor- (PAF), or interleukin (IL)-5-induced eosinophilia, and of lipopolysaccharide-(LPS), tumour necrosis factor alpha-(TNF alpha) or cytokine-induced neutrophil chemoattractant- (CINC) induced neutrophilia in guinea-pig lungs. Dexamethasone was a potent inhibitor of PAF- induced eosinophil accumulation, but higher doses of dexamethasone were required to inhibit IL-5-induced eosinophilia. LPS-induced neutrophilia was less sensitive to the inhibitory effects of dexamethasone, than PAF-induced eosinophilia. Both LPS- and TNF alpha-induced neutrophilia were inhibited by the same doses of dexamethasone. In contrast, higher doses of dexamethasone were required to inhibit CINC-induced neutrophilia. Since data in the literature show that PAF-induced eosinophilia in guinea-pig lungs is dependent on the generation of IL-5, it is concluded that inhibition of this response, by dexamethasone, is due to inhibition of release of IL-5. Similarly, although data in the literature show that LPS-induced neutrophilia is dependent on the generation of TNF alpha, it is concluded that inhibition of this response, by glucocorticoids, is due to an action on an event which occurs after the release of TNF alpha, possibly through inhibition of chemokine release.

The effects of NZ-107 on some airway inflammation models and the generation of superoxide anion (O2-) were studied in guinea-pigs. Airway inflammation was caused by intra-tracheal injection of murine recombinant interleukin-5 (mrIL-5, 15 micrograms/animal), inhalation of platelet-activating factor (PAF, 0.003%) and intra-tracheal injection of leukotriene B4 (LTB4, 10 micrograms/animal). NZ-107 (4-bromo-5-(3-ethoxy-4-methoxybenzylamino)-3(2H)-pyridazinone) at a dose of 50 mg kg-1, intraperitoneally reduced mrIL-5- and PAF-induced eosinophilia. This compound at a dose of 25 and 50 mg kg-1 also suppressed LTB4-induced eosinophilia and neutrophilia in bronchoalveolar lavage fluid (BALF). On the other hand, prednisolone at a dose of 20 mg kg-1, i.p., prevented the increased number of macrophages, eosinophils and neutrophils induced by mrIL-5, the increased number of eosinophils induced by PAF and the increased number of eosinophils and neutrophils induced by LTB4 in BALF. Furthermore, both drugs reduced mrIL-5- or PAF-induced increase in the number of airway epithelial cells in BALF. The generation of O2- was measured by the method of cytochrome C reduction. NZ-107 (10-100 micrograms mL-1) attenuated PAF- and FMLP-induced O2- production from macrophages and reduced PAF-induced O2- generation by eosinophils but had no effect on that from neutrophils. These results indicate that NZ-107 prevents the increased number of pulmonary eosinophils and airway epithelial cells and the activation of macrophages and eosinophils, suggesting that NZ-107 may be useful as a remedy for airway inflammatory diseases such as bronchial asthma.