IL-4Rα signalling in B cells and T cells play differential roles in acute and chronic atopic dermatitis.

Atopic dermatitis (AD) is a common pruritic inflammatory skin disease with complex environmental and genetic predisposing factors. Primary skin barrier dysfunction and aberrant T helper 2 (TH2) responses to common allergens, together with increased serum IgE antibodies, characterise the disease. B and T cells are essential in the disease manifestation, however, the exact mechanism of how these cells is involved is unclear. Targeting interleukin 4 receptor alpha (IL-4Rα), an IL-4/IL-13 signalling axis, with dupilumab shows efficacy in AD. We investigated the importance of IL-4Rα signalling specifically on B and T cells during acute and chronic models of AD. We used House dust mite (HDM) and Ovalbumin (OVA) in chronic models and a low-calcemic analog of vitamin D (MC903) for acute models of AD. We used mb1creIL-4Rα-/lox, iLCKcreIL-4Rα-/lox, LCKcreIL-4Rα-/lox, CD4creIL-4Rα-/lox, Foxp3creIL-4Rα-/lox and IL-4Rα-/lox littermate controls. IL-4Rα-responsive B cells were essential in serum IgE levels, but not in epidermal thickening in both chronic and acute models. IL-4Rα-responsive T cells were essential in epidermal thickening in the pan-T cell, but not CD4 or CD8 T cells suggesting the importance of γδT cells during acute AD. Our results suggest that IL-4Rα responsiveness on innate T cells regulates acute atopic dermatitis, while on B cells it regulates IgE.

Deletion of IL-4Rα signaling on B cells limits hyperresponsiveness depending on antigen load.

BACKGROUND: B cells play an important role in allergies through secretion of IgE. IL-4 receptor α (IL-4Rα) is key in allergic asthma and regulates type 2 cytokine production, IgE secretion, and airway hyperresponsiveness. IL-4 activation of B cells is essential for class switching and contributes to the induction of B effector 2 (Be2) cells. The role of Be2 cells and signaling via IL-4Rα in B cells is not clearly defined. OBJECTIVE: We sought to find out whether IL-4Rα-responsive B cells or Be2 function was essential in experimental allergic asthma. METHODS: Mice lacking IL-4Rα on B cells (mb1creIL-4Rα-/lox) or littermate controls (IL-4Rα-/lox) and mice lacking IL-4 or IL-4/IL-13 on B cells were sensitized and challenged with high-dose house dust mite (>10 µg) or with low-dose house dust mite (<3 µg). We also adoptively transferred naive IL-4Rα-/lox or IL-4Rα-/- B cells into µMT-/- mice a day before sensitization or a day before challenge. We analyzed lung inflammation, cellular infiltrate, and airway hyperresponsiveness. RESULTS: We found that IL-4Rα signaling on B cells was important for optimal TH2 allergic immune responses mainly when the load of antigen is limited. IL-4Rα signaling on B cells was essential for germinal centers and in the effector phase of allergic responses. Be2 cells were essential in airway hyperresponsiveness, but not in other parameters. CONCLUSIONS: IL-4Rα signaling on B cells is deleterious in allergic asthma because it is required for optimal TH2 responses, Be2 function, germinal center formation, and T follicular helper cells, especially when the load of the antigen is limiting.

Therapeutic and prophylactic deletion of IL-4Ra-signaling ameliorates established ovalbumin induced allergic asthma.

BACKGROUND: Allergic asthma is a chronic inflammatory airway disease driven predominantly by a TH 2 immune response to environmental allergens. IL-4Rα-signaling is essential for driving TH 2-type immunity to allergens. Anti-TH 2 therapies have the potential to effectively reduce airway obstruction and inflammation in allergic asthma. OBJECTIVE: We investigated potential therapeutic effects of selective inhibition of this pathway in mice with established allergic airway disease. We further investigated whether IL-4Rα disruption in systemically sensitized mice can prevent the onset of the disease. METHODS: We used RosacreERT2 IL-4Rα-/lox mice, a tamoxifen (TAM)-inducible IL-4Rα knockdown model to investigate the role of IL-4/IL-13 signaling prior to the onset of the disease and during the effector phase in the ovalbumin-induced allergic airway disease. RESULTS: Inducible deletion of IL-4Rα demonstrated therapeutic effects, on established allergic airway disease, and prevented the development of ovalbumin-induced airway hyperreactivity, eosinophilia, and goblet cell metaplasia in allergen-sensitized mice. Interestingly, IL-4Rα knockdown after allergic sensitization did not induce TH 17, a neutrophilic inflammatory response as observed in global IL-4Rα-deficient mice after intranasal allergen challenge. CONCLUSION: Abrogation of IL-4Rα signaling after allergic sensitization would have significant therapeutic benefit for TH 2-type allergic asthma.

Short stimulation of electro-responsive PAA/fibrin hydrogel induces collagen production.

Acrylic acid/fibrin hydrogel can mechanically stimulate cells when an external electrical field is applied, enabling them to migrate and align throughout the depth of the gel. The ability of electro-responsive polyacrylic acid (PAA)/fibrin hydrogel to promote collagen production and remodeling has been investigated by three-dimensional (3D) culturing and conditioning of smooth muscle cells (SMCs). SMCs-seeded hydrogels were subjected to an alternating electrical field (0.06 V/mm) for 2 h for one, two, or three times per week during 4 weeks of culturing. Fluorescent images of collagen structure and accumulation, assessed by CNA-35 probe, showed increased collagen content (>100-fold at 1× stimulation/week) in the center of the hydrogels after 4 weeks of culture. The increase in collagen production correlated with increasing extracellular matrix gene expression and resulted in significantly improved mechanical properties of the stimulated hydrogels. Matrix metalloproteinase (MMP)-2 activity was also significantly enhanced by stimulation, which probably has a role in the reorganization of the collagen. Short stimulation (2 h) induced a favorable response in the cells and enhanced tissue formation and integrity of the scaffold by inducing collagen production. The presented set up could be used for conditioning and improving the functionality of current tissue-engineered vascular grafts.