Mutations in human DOCK8 cause a combined immunodeficiency syndrome characterized by allergic diseases such as asthma and food allergy. However, the underlying mechanism is unclear. Regulatory B (Breg) cells that produce IL-10 exert potent immunosuppressive functions in patients with allergic and autoimmune disorders. DOCK8-deficient B cells show diminished responses to TLR9 signaling, suggesting a possible defect in IL-10-producing Breg cells in those with DOCK8 deficiency, which may contribute to allergies. Here, we isolated peripheral blood mononuclear cells from DOCK8-deficient patients and generated a Dock8 KO mouse model to study the effect of DOCK8 deficiency on Breg cells. DOCK8-deficient patients and Dock8 KO mice harbored quantitative and qualitative defects in IL-10-producing Breg cells; these defects were caused by abnormal Dock8(-/-) CD4(+) T cells. We found that recombinant murine (rm)IL-21 restored the function of Bregs both in vitro and in Dock8 KO mice, leading to reduced inflammatory cell infiltration of the lungs in a murine asthma model. Overall, the results provide new insight into the potential design of Breg-based or IL-21-based therapeutic strategies for allergic diseases, including asthma associated with DOCK8 deficiency.

Objective To compare the different methods of administration of diacetyl (DA)-established bronchiolitis obliterans (BO)murine model so as to establish a simple,easy-to-operate and stable BO murine model. Methods SPF grade C57BL/6 male mice (6 to 8 weeks)were randomly divided into four groups with 10 mice in each group:oropharyngeal aspiration group (OPR),intratracheal instillation group (ITI),and control groups (OPR-CON and ITI-CON).OPR group was treated with DA (400 mg/kg,327 mg/kg)by oropharyngeal aspiration;ITI group received DA (400 mg/kg,327 mg/mL)through intratracheal instillation;OPR-CON group and ITI-CON group were treated with sterilized distilled water instead of DA,while the other experimental conditions were the same as those in OPR and ITI groups.The mice were kept in SPF-class animal center for 7 d to collect specimens. Collected bronchoalveolar lavage fluid (BALF)and the left lung were examined pathologically.Results Male C57 BL/6 mice were treated with a single dose of DA (400 mg/kg,327 mg/kg)by OPR or ITI,which could establish BO model.The successful model was evaluated by pulmonary function,BALF counts and pathological examination. Airway hyperresponsiveness occurred with the two-method resulted BO.And two methods of instilling DA resulted in airway injury,lumen occlusion,infiltration of inflammatory cells in the airway and around the vessels.The mortality rate of mice was up to 60% and the success of model construction was only 20% in BO model by oropharyngeal aspiration of DA,while that in ITI group mortality was only 30%,the success of model construction was up to 60%.There was no death in control groups.Conclusion BO murine model could be successfully established by OPR or ITI of DA (400 mg/kg,327 mg/mL).However,the BO model was established well by ITI of DA with lower mortality rate.Therefore,ITI of DA-established BO murine model is recommended for use.

Patients with DOCK8 deficiency are at increased susceptibility to develop allergic diseases such as food allergy and asthma. Here, we aimed to analyze the pathogenesis of asthma in DOCK8-deficient patients. In our mouse model, DOCK8-knockout (KO) mice sensitized with low-dose OVA were challenged with 1.5% OVA to induce allergic asthma. As compared to that in WT mice, remarkable airway hyperresponsiveness was observed in KO mice. Increased inflammatory cells and eosinophils infiltrated in airway lumen in KO mice especially around bronchi. KO mice showed higher levels of serum IgE and OVA-specific IgE and significantly elevated IgE-producing B cells in blood and in spleen. Surprisingly, nasal administration with rmIL-21 significantly reduced the airway hyperresponsiveness, inflammatory infiltration, as well as the serum IgE and IgE-producing B cells. DOCK8-knockout mice are susceptible to low-dose OVA induced allergic airway inflammation and airway hyperresponsiveness. Supplementary nasal administration of rmIL-21 alleviates allergic asthma in this mouse model.