[Lymphocyte trafficking and immunesurveillance]

Insights from DOCK2 in cell function and pathophysiology

Dedicator of cytokinesis 2 (DOCK2) can activate the downstream small G protein Rac and regulate cytoskeletal reorganization. DOCK2 is essential for critical physiological processes such as migration, activation, proliferation, and effects of immune cells, including lymphocytes, neutrophils, macrophages, and dendritic cells. For example, DOCK2 is involved in the development and activation of T and B lymphocytes by affecting synapse formation and inhibiting the development of the Th2 lineage by downregulating IL-4Rα surface expression. Not only that, DOCK2 may be a molecular target for controlling cardiac transplant rejection and Alzheimer’s disease (AD). Patients with defects in the DOCK2 gene also exhibit a variety of impaired cellular functions, such as chemotactic responses of lymphocytes and reactive oxygen species (ROS) production by neutrophils. To date, DOCK2 has been shown to be involved in the development of various diseases, including AD, pneumonia, myocarditis, colitis, tumors, etc. DOCK2 plays different roles in these diseases and the degree of inflammatory response has a different impact on the progression of disease. In this paper, we present a review of recent advances in the function of DOCK2 in various immune cells and its role in various diseases.

Toll-Like Receptor 4-Myeloid Differentiation Primary Response Gene 88 Pathway Is Involved in the Inflammatory Development of Polymyositis by Mediating Interferon-γ and Interleukin-17A in Humans and Experimental Autoimmune Myositis Mouse Model

OBJECTIVE

Toll-like receptor 4 (TLR4) is one of the key players in the development of many autoimmune diseases. To determine the possible role of TLR4 in polymyositis (PM) development, we collected muscle samples from PM patients and mice subjected to an experimental autoimmune myositis (EAM) model.

METHODS

We measured TLR4-MyD88 pathway-related factors, interferon-γ (IFN-γ), and interleukin-17A (IL-17A) in EAM mice and PM patients. Then, we observed the changes of above factors and the inflammatory development of EAM mice with TLR4 antagonist TAK-242, IFN-γ, or IL-17A antibody treatment.

RESULTS

The expression of TLR4, MyD88, and NF-κB was significantly upregulated in the muscle tissues both in 22 patients with PM and in the EAM model. As expected, increased levels of various cytokines, such as IL-1β, IL-6, IL-10, IL-12, tumor necrosis factor-α, TGF-β, IFN-γ, and IL-17A, were evident in the serum of EAM mice. Moreover, mRNA expression levels of IFN-γ and IL-17A were significantly increased in both PM patients and EAM mice. Consistently, the levels of these factors were positively correlated with the degree of muscle inflammation in EAM mice. However, when EAM mice were treated with TLR4 antagonist TAK-242, the expression of IFN-γ and IL-17A was decreased. When the cytokines were neutralized by anti-IFN-γ or anti-IL-17A antibody, the inflammatory development of EAM exacerbated or mitigated.

CONCLUSION

The present study provided the important evidence that the TLR4-MyD88 pathway may be involved in the immune mechanisms of PM by mediating IFN-γ and IL-17A.

Progress of gut associated lymphocyte homing in inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of intestinal tract, and it is classified into 2 subtypes traditionally, namely ulcerative colitis (UC) and Crohn's disease (CD). Many investigations have shown that intestinal lymphocyte homing (lymphocyte homing, LH) is closely related to IBD. This paper reviews the advances in the relationship between inflammatory bowel disease and lymphocyte homing.