Interleukin‑27 ameliorates allergic asthma by alleviating the lung Th2 inflammatory environment

The dichotomic role of single cytokines: Fine-tuning immune responses

Cytokines are known for their pleiotropic effects. They can be classified by their function as pro-inflammatory, such as tumor necrosis factor (TNF), interleukin (IL) 1 and IL-12, or anti-inflammatory, like IL-10, IL-35 and transforming growth factor β (TGF-β). Though this type of classification is an important simplification for the understanding of the general cytokine's role, it can be misleading. Here, we discuss recent studies that show a dichotomic role of the so-called pro and anti-inflammatory cytokines, highlighting that their function can be dependent on the microenvironment and their concentrations. Furthermore, we discuss how the back-and-forth interplay between cytokines and immunometabolism can influence the dichotomic role of inflammatory responses as an important target to complement cytokine-based therapies.

Regulatory T cells in lung disease and transplantation

Pulmonary disease can refer to the disease of the lung itself or the pulmonary manifestations of systemic diseases, which are often connected to the malfunction of the immune system. Regulatory T (Treg) cells have been shown to be important in maintaining immune homeostasis and preventing inflammatory damage, including lung diseases. Given the increasing amount of evidence linking Treg cells to various pulmonary conditions, Treg cells might serve as a therapeutic strategy for the treatment of lung diseases and potentially promote lung transplant tolerance. The most potent and well-defined Treg cells are Foxp3-expressing CD4+ Treg cells, which contribute to the prevention of autoimmune lung diseases and the promotion of lung transplant rejection. The protective mechanisms of Treg cells in lung disease and transplantation involve multiple immune suppression mechanisms. This review summarizes the development, phenotype and function of CD4+Foxp3+ Treg cells. Then, we focus on the therapeutic potential of Treg cells in preventing lung disease and limiting lung transplant rejection. Furthermore, we discussed the possibility of Treg cell utilization in clinical applications. This will provide an overview of current research advances in Treg cells and their relevant application in clinics.

CD200Fc limits dendritic cell and B-cell activation during chronic allergen exposures

Allergic asthma is a chronic inflammatory disease characterized by Th2, conventional dendritic cell, and B-cell activation. In addition to excessive inflammation, asthma pathogenesis includes dysregulation of anti-inflammatory pathways, such as the CD200/CD200R pathway. Thus, we investigated whether a CD200R agonist, CD200Fc, could disrupt the inflammatory cascade in chronic allergic asthma pathogenesis using a mice model of experimental asthma. Mice were exposed to house dust mites for 5 wk, and CD200Fc treatment was initiated after chronic inflammation was established (starting on week 4). We demonstrate that chronic house dust mite exposure altered CD200 and CD200R expression on lung immune cell populations, including upregulation of CD200 on alveolar macrophages and reduced expression of CD200 on conventional dendritic cells. CD200Fc treatment does not change bronchoalveolar cellular infiltration, but it attenuates B-cell activation and skews the circulating immunoglobulin profile toward IgG2a. This is accompanied by reduced activation of conventional dendritic cells, including lower expression of CD40, especially on conventional dendritic cell subset 2 CD200R+. Furthermore, we confirm that CD200Fc can directly modulate conventional dendritic cell activation in vitro using bone marrow-derived dendritic cells. Thus, the CD200/CD200R pathway is dysregulated during chronic asthma pathogenesis, and the CD200R agonist modulates B-cell and dendritic cell activation but, in our chronic model, is not sufficient to alter inflammation measured in bronchoalveolar lavage.